Bump version numbers for beta release.

Backport: Enable LAN plugin when providing a wifi access point

See merge request akwizgran/briar!755

bramble-android/build.gradle

@@ -12,8 +12,8 @@ android {
 	defaultConfig {
 		minSdkVersion 14
 		targetSdkVersion 26
-		versionCode 1612
-		versionName "0.16.12"
+		versionCode 1620
+		versionName "0.16.20"
 		consumerProguardFiles 'proguard-rules.txt'
 	}
 
@@ -54,16 +54,16 @@ dependencyVerification {
 }
 
 ext.torBinaryDir = 'src/main/res/raw'
-ext.torVersion = '0.2.9.12'
-ext.geoipVersion = '2017-09-06'
+ext.torVersion = '0.2.9.14'
+ext.geoipVersion = '2017-11-06'
 ext.torDownloadUrl = 'https://briarproject.org/build/'
 
 def torBinaries = [
-		"tor_arm"    : '8ed0b347ffed1d6a4d2fd14495118eb92be83e9cc06e057e15220dc288b31688',
-		"tor_arm_pie": '64403262511c29f462ca5e7c7621bfc3c944898364d1d5ad35a016bb8a034283',
-		"tor_x86"    : '61e014607a2079bcf1646289c67bff6372b1aded6e1d8d83d7791efda9a4d5ab',
-		"tor_x86_pie": '18fbc98356697dd0895836ab46d5c9877d1c539193464f7db1e82a65adaaf288',
-		"geoip"      : 'fe49d3adb86d3c512373101422a017dbb86c85a570524663f09dd8ce143a24f3'
+		"tor_arm"    : '1710ea6c47b7f4c1a88bdf4858c7893837635db10e8866854eed8d61629f50e8',
+		"tor_arm_pie": '974e6949507db8fa2ea45231817c2c3677ed4ccf5488a2252317d744b0be1917',
+		"tor_x86"    : '3a5e45b3f051fcda9353b098b7086e762ffe7ba9242f7d7c8bf6523faaa8b1e9',
+		"tor_x86_pie": 'd1d96d8ce1a4b68accf04850185780d10cd5563d3552f7e1f040f8ca32cb4e51',
+		"geoip"      : '8239b98374493529a29096e45fc5877d4d6fdad0146ad8380b291f90d61484ea'
 ]
 
 def downloadBinary(name) {

bramble-android/src/main/java/org/briarproject/bramble/plugin/AndroidPluginModule.java

@@ -13,7 +13,8 @@ import org.briarproject.bramble.api.plugin.simplex.SimplexPluginFactory;
 import org.briarproject.bramble.api.reporting.DevReporter;
 import org.briarproject.bramble.api.system.AndroidExecutor;
 import org.briarproject.bramble.api.system.LocationUtils;
-import org.briarproject.bramble.plugin.droidtooth.DroidtoothPluginFactory;
+import org.briarproject.bramble.api.system.Scheduler;
+import org.briarproject.bramble.plugin.bluetooth.AndroidBluetoothPluginFactory;
 import org.briarproject.bramble.plugin.tcp.AndroidLanTcpPluginFactory;
 import org.briarproject.bramble.plugin.tor.TorPluginFactory;
 
@@ -22,6 +23,7 @@ import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.concurrent.Executor;
+import java.util.concurrent.ScheduledExecutorService;
 
 import javax.net.SocketFactory;
 
@@ -33,18 +35,20 @@ public class AndroidPluginModule {
 
 	@Provides
 	PluginConfig providePluginConfig(@IoExecutor Executor ioExecutor,
+			@Scheduler ScheduledExecutorService scheduler,
 			AndroidExecutor androidExecutor, SecureRandom random,
 			SocketFactory torSocketFactory, BackoffFactory backoffFactory,
 			Application app, LocationUtils locationUtils, DevReporter reporter,
 			EventBus eventBus) {
 		Context appContext = app.getApplicationContext();
-		DuplexPluginFactory bluetooth = new DroidtoothPluginFactory(ioExecutor,
-				androidExecutor, appContext, random, eventBus, backoffFactory);
-		DuplexPluginFactory tor = new TorPluginFactory(ioExecutor, appContext,
-				locationUtils, reporter, eventBus, torSocketFactory,
-				backoffFactory);
+		DuplexPluginFactory bluetooth =
+				new AndroidBluetoothPluginFactory(ioExecutor, androidExecutor,
+						appContext, random, eventBus, backoffFactory);
+		DuplexPluginFactory tor = new TorPluginFactory(ioExecutor, scheduler,
+				appContext, locationUtils, reporter, eventBus,
+				torSocketFactory, backoffFactory);
 		DuplexPluginFactory lan = new AndroidLanTcpPluginFactory(ioExecutor,
-				backoffFactory, appContext);
+				scheduler, backoffFactory, appContext);
 		Collection<DuplexPluginFactory> duplex =
 				Arrays.asList(bluetooth, tor, lan);
 		@NotNullByDefault

bramble-android/src/main/java/org/briarproject/bramble/plugin/bluetooth/AndroidBluetoothPlugin.java

@@ -0,0 +1,206 @@
+package org.briarproject.bramble.plugin.bluetooth;
+
+import android.bluetooth.BluetoothAdapter;
+import android.bluetooth.BluetoothDevice;
+import android.bluetooth.BluetoothServerSocket;
+import android.bluetooth.BluetoothSocket;
+import android.content.BroadcastReceiver;
+import android.content.Context;
+import android.content.Intent;
+import android.content.IntentFilter;
+
+import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
+import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
+import org.briarproject.bramble.api.plugin.Backoff;
+import org.briarproject.bramble.api.plugin.PluginException;
+import org.briarproject.bramble.api.plugin.duplex.DuplexPluginCallback;
+import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
+import org.briarproject.bramble.api.system.AndroidExecutor;
+import org.briarproject.bramble.util.AndroidUtils;
+
+import java.io.Closeable;
+import java.io.IOException;
+import java.security.SecureRandom;
+import java.util.UUID;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.Executor;
+import java.util.logging.Logger;
+
+import javax.annotation.Nullable;
+
+import static android.bluetooth.BluetoothAdapter.ACTION_SCAN_MODE_CHANGED;
+import static android.bluetooth.BluetoothAdapter.ACTION_STATE_CHANGED;
+import static android.bluetooth.BluetoothAdapter.EXTRA_SCAN_MODE;
+import static android.bluetooth.BluetoothAdapter.EXTRA_STATE;
+import static android.bluetooth.BluetoothAdapter.SCAN_MODE_CONNECTABLE;
+import static android.bluetooth.BluetoothAdapter.SCAN_MODE_CONNECTABLE_DISCOVERABLE;
+import static android.bluetooth.BluetoothAdapter.SCAN_MODE_NONE;
+import static android.bluetooth.BluetoothAdapter.STATE_OFF;
+import static android.bluetooth.BluetoothAdapter.STATE_ON;
+import static java.util.logging.Level.WARNING;
+
+@MethodsNotNullByDefault
+@ParametersNotNullByDefault
+class AndroidBluetoothPlugin extends BluetoothPlugin<BluetoothServerSocket> {
+
+	private static final Logger LOG =
+			Logger.getLogger(AndroidBluetoothPlugin.class.getName());
+
+	private final AndroidExecutor androidExecutor;
+	private final Context appContext;
+
+	private volatile boolean wasEnabledByUs = false;
+	private volatile BluetoothStateReceiver receiver = null;
+
+	// Non-null if the plugin started successfully
+	private volatile BluetoothAdapter adapter = null;
+
+	AndroidBluetoothPlugin(Executor ioExecutor, AndroidExecutor androidExecutor,
+			Context appContext, SecureRandom secureRandom, Backoff backoff,
+			DuplexPluginCallback callback, int maxLatency) {
+		super(ioExecutor, secureRandom, backoff, callback, maxLatency);
+		this.androidExecutor = androidExecutor;
+		this.appContext = appContext;
+	}
+
+	@Override
+	public void start() throws PluginException {
+		super.start();
+		// Listen for changes to the Bluetooth state
+		IntentFilter filter = new IntentFilter();
+		filter.addAction(ACTION_STATE_CHANGED);
+		filter.addAction(ACTION_SCAN_MODE_CHANGED);
+		receiver = new BluetoothStateReceiver();
+		appContext.registerReceiver(receiver, filter);
+	}
+
+	@Override
+	public void stop() {
+		super.stop();
+		if (receiver != null) appContext.unregisterReceiver(receiver);
+	}
+
+	@Override
+	void initialiseAdapter() throws IOException {
+		// BluetoothAdapter.getDefaultAdapter() must be called on a thread
+		// with a message queue, so submit it to the AndroidExecutor
+		try {
+			adapter = androidExecutor.runOnBackgroundThread(
+					BluetoothAdapter::getDefaultAdapter).get();
+		} catch (InterruptedException | ExecutionException e) {
+			throw new IOException(e);
+		}
+		if (adapter == null)
+			throw new IOException("Bluetooth is not supported");
+	}
+
+	@Override
+	boolean isAdapterEnabled() {
+		return adapter != null && adapter.isEnabled();
+	}
+
+	@Override
+	void enableAdapter() {
+		if (adapter != null && !adapter.isEnabled()) {
+			if (adapter.enable()) {
+				LOG.info("Enabling Bluetooth");
+				wasEnabledByUs = true;
+			} else {
+				LOG.info("Could not enable Bluetooth");
+			}
+		}
+	}
+
+	@Override
+	void disableAdapterIfEnabledByUs() {
+		if (isAdapterEnabled() && wasEnabledByUs) {
+			if (adapter.disable()) LOG.info("Disabling Bluetooth");
+			else LOG.info("Could not disable Bluetooth");
+			wasEnabledByUs = false;
+		}
+	}
+
+	@Override
+	void setEnabledByUs() {
+		wasEnabledByUs = true;
+	}
+
+	@Override
+	@Nullable
+	String getBluetoothAddress() {
+		String address = AndroidUtils.getBluetoothAddress(appContext, adapter);
+		return address.isEmpty() ? null : address;
+	}
+
+	@Override
+	BluetoothServerSocket openServerSocket(String uuid) throws IOException {
+		return adapter.listenUsingInsecureRfcommWithServiceRecord(
+				"RFCOMM", UUID.fromString(uuid));
+	}
+
+	@Override
+	void tryToClose(@Nullable BluetoothServerSocket ss) {
+		try {
+			if (ss != null) ss.close();
+		} catch (IOException e) {
+			if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
+		}
+	}
+
+	@Override
+	DuplexTransportConnection acceptConnection(BluetoothServerSocket ss)
+			throws IOException {
+		return wrapSocket(ss.accept());
+	}
+
+	private DuplexTransportConnection wrapSocket(BluetoothSocket s) {
+		return new AndroidBluetoothTransportConnection(this, s);
+	}
+
+	@Override
+	boolean isValidAddress(String address) {
+		return BluetoothAdapter.checkBluetoothAddress(address);
+	}
+
+	@Override
+	DuplexTransportConnection connectTo(String address, String uuid)
+			throws IOException {
+		BluetoothDevice d = adapter.getRemoteDevice(address);
+		UUID u = UUID.fromString(uuid);
+		BluetoothSocket s = null;
+		try {
+			s = d.createInsecureRfcommSocketToServiceRecord(u);
+			s.connect();
+			return wrapSocket(s);
+		} catch (IOException e) {
+			tryToClose(s);
+			throw e;
+		}
+	}
+
+	private void tryToClose(@Nullable Closeable c) {
+		try {
+			if (c != null) c.close();
+		} catch (IOException e) {
+			if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
+		}
+	}
+
+	private class BluetoothStateReceiver extends BroadcastReceiver {
+
+		@Override
+		public void onReceive(Context ctx, Intent intent) {
+			int state = intent.getIntExtra(EXTRA_STATE, 0);
+			if (state == STATE_ON) onAdapterEnabled();
+			else if (state == STATE_OFF) onAdapterDisabled();
+			int scanMode = intent.getIntExtra(EXTRA_SCAN_MODE, 0);
+			if (scanMode == SCAN_MODE_NONE) {
+				LOG.info("Scan mode: None");
+			} else if (scanMode == SCAN_MODE_CONNECTABLE) {
+				LOG.info("Scan mode: Connectable");
+			} else if (scanMode == SCAN_MODE_CONNECTABLE_DISCOVERABLE) {
+				LOG.info("Scan mode: Discoverable");
+			}
+		}
+	}
+}

bramble-android/src/main/java/org/briarproject/bramble/plugin/bluetooth/AndroidBluetoothPluginFactory.java

@@ -1,4 +1,4 @@
-package org.briarproject.bramble.plugin.droidtooth;
+package org.briarproject.bramble.plugin.bluetooth;
 
 import android.content.Context;
 
@@ -21,7 +21,7 @@ import static org.briarproject.bramble.api.plugin.BluetoothConstants.ID;
 
 @Immutable
 @NotNullByDefault
-public class DroidtoothPluginFactory implements DuplexPluginFactory {
+public class AndroidBluetoothPluginFactory implements DuplexPluginFactory {
 
 	private static final int MAX_LATENCY = 30 * 1000; // 30 seconds
 	private static final int MIN_POLLING_INTERVAL = 60 * 1000; // 1 minute
@@ -35,7 +35,7 @@ public class DroidtoothPluginFactory implements DuplexPluginFactory {
 	private final EventBus eventBus;
 	private final BackoffFactory backoffFactory;
 
-	public DroidtoothPluginFactory(Executor ioExecutor,
+	public AndroidBluetoothPluginFactory(Executor ioExecutor,
 			AndroidExecutor androidExecutor, Context appContext,
 			SecureRandom secureRandom, EventBus eventBus,
 			BackoffFactory backoffFactory) {
@@ -61,7 +61,7 @@ public class DroidtoothPluginFactory implements DuplexPluginFactory {
 	public DuplexPlugin createPlugin(DuplexPluginCallback callback) {
 		Backoff backoff = backoffFactory.createBackoff(MIN_POLLING_INTERVAL,
 				MAX_POLLING_INTERVAL, BACKOFF_BASE);
-		DroidtoothPlugin plugin = new DroidtoothPlugin(ioExecutor,
+		AndroidBluetoothPlugin plugin = new AndroidBluetoothPlugin(ioExecutor,
 				androidExecutor, appContext, secureRandom, backoff, callback,
 				MAX_LATENCY);
 		eventBus.addListener(plugin);

bramble-android/src/main/java/org/briarproject/bramble/plugin/bluetooth/AndroidBluetoothTransportConnection.java

@@ -1,4 +1,4 @@
-package org.briarproject.bramble.plugin.droidtooth;
+package org.briarproject.bramble.plugin.bluetooth;
 
 import android.bluetooth.BluetoothSocket;
 
@@ -11,11 +11,12 @@ import java.io.InputStream;
 import java.io.OutputStream;
 
 @NotNullByDefault
-class DroidtoothTransportConnection extends AbstractDuplexTransportConnection {
+class AndroidBluetoothTransportConnection
+		extends AbstractDuplexTransportConnection {
 
 	private final BluetoothSocket socket;
 
-	DroidtoothTransportConnection(Plugin plugin, BluetoothSocket socket) {
+	AndroidBluetoothTransportConnection(Plugin plugin, BluetoothSocket socket) {
 		super(plugin);
 		this.socket = socket;
 	}

bramble-android/src/main/java/org/briarproject/bramble/plugin/droidtooth/DroidtoothPlugin.java

@@ -1,490 +0,0 @@
-package org.briarproject.bramble.plugin.droidtooth;
-
-import android.bluetooth.BluetoothAdapter;
-import android.bluetooth.BluetoothDevice;
-import android.bluetooth.BluetoothServerSocket;
-import android.bluetooth.BluetoothSocket;
-import android.content.BroadcastReceiver;
-import android.content.Context;
-import android.content.Intent;
-import android.content.IntentFilter;
-
-import org.briarproject.bramble.api.FormatException;
-import org.briarproject.bramble.api.contact.ContactId;
-import org.briarproject.bramble.api.data.BdfList;
-import org.briarproject.bramble.api.event.Event;
-import org.briarproject.bramble.api.event.EventListener;
-import org.briarproject.bramble.api.keyagreement.KeyAgreementConnection;
-import org.briarproject.bramble.api.keyagreement.KeyAgreementListener;
-import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
-import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
-import org.briarproject.bramble.api.plugin.Backoff;
-import org.briarproject.bramble.api.plugin.PluginException;
-import org.briarproject.bramble.api.plugin.TransportId;
-import org.briarproject.bramble.api.plugin.duplex.DuplexPlugin;
-import org.briarproject.bramble.api.plugin.duplex.DuplexPluginCallback;
-import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
-import org.briarproject.bramble.api.plugin.event.DisableBluetoothEvent;
-import org.briarproject.bramble.api.plugin.event.EnableBluetoothEvent;
-import org.briarproject.bramble.api.properties.TransportProperties;
-import org.briarproject.bramble.api.system.AndroidExecutor;
-import org.briarproject.bramble.util.AndroidUtils;
-import org.briarproject.bramble.util.StringUtils;
-
-import java.io.Closeable;
-import java.io.IOException;
-import java.security.SecureRandom;
-import java.util.Collection;
-import java.util.Map;
-import java.util.Map.Entry;
-import java.util.UUID;
-import java.util.concurrent.Callable;
-import java.util.concurrent.ExecutionException;
-import java.util.concurrent.Executor;
-import java.util.concurrent.atomic.AtomicBoolean;
-import java.util.logging.Logger;
-
-import javax.annotation.Nullable;
-
-import static android.bluetooth.BluetoothAdapter.ACTION_SCAN_MODE_CHANGED;
-import static android.bluetooth.BluetoothAdapter.ACTION_STATE_CHANGED;
-import static android.bluetooth.BluetoothAdapter.EXTRA_SCAN_MODE;
-import static android.bluetooth.BluetoothAdapter.EXTRA_STATE;
-import static android.bluetooth.BluetoothAdapter.SCAN_MODE_CONNECTABLE;
-import static android.bluetooth.BluetoothAdapter.SCAN_MODE_CONNECTABLE_DISCOVERABLE;
-import static android.bluetooth.BluetoothAdapter.SCAN_MODE_NONE;
-import static android.bluetooth.BluetoothAdapter.STATE_OFF;
-import static android.bluetooth.BluetoothAdapter.STATE_ON;
-import static java.util.logging.Level.INFO;
-import static java.util.logging.Level.WARNING;
-import static org.briarproject.bramble.api.keyagreement.KeyAgreementConstants.TRANSPORT_ID_BLUETOOTH;
-import static org.briarproject.bramble.api.plugin.BluetoothConstants.ID;
-import static org.briarproject.bramble.api.plugin.BluetoothConstants.PREF_BT_ENABLE;
-import static org.briarproject.bramble.api.plugin.BluetoothConstants.PROP_ADDRESS;
-import static org.briarproject.bramble.api.plugin.BluetoothConstants.PROP_UUID;
-import static org.briarproject.bramble.api.plugin.BluetoothConstants.UUID_BYTES;
-import static org.briarproject.bramble.util.PrivacyUtils.scrubMacAddress;
-
-@MethodsNotNullByDefault
-@ParametersNotNullByDefault
-class DroidtoothPlugin implements DuplexPlugin, EventListener {
-
-	private static final Logger LOG =
-			Logger.getLogger(DroidtoothPlugin.class.getName());
-
-	private final Executor ioExecutor;
-	private final AndroidExecutor androidExecutor;
-	private final Context appContext;
-	private final SecureRandom secureRandom;
-	private final Backoff backoff;
-	private final DuplexPluginCallback callback;
-	private final int maxLatency;
-	private final AtomicBoolean used = new AtomicBoolean(false);
-
-	private volatile boolean running = false;
-	private volatile boolean wasEnabledByUs = false;
-	private volatile BluetoothStateReceiver receiver = null;
-	private volatile BluetoothServerSocket socket = null;
-
-	// Non-null if the plugin started successfully
-	private volatile BluetoothAdapter adapter = null;
-
-	DroidtoothPlugin(Executor ioExecutor, AndroidExecutor androidExecutor,
-			Context appContext, SecureRandom secureRandom, Backoff backoff,
-			DuplexPluginCallback callback, int maxLatency) {
-		this.ioExecutor = ioExecutor;
-		this.androidExecutor = androidExecutor;
-		this.appContext = appContext;
-		this.secureRandom = secureRandom;
-		this.backoff = backoff;
-		this.callback = callback;
-		this.maxLatency = maxLatency;
-	}
-
-	@Override
-	public TransportId getId() {
-		return ID;
-	}
-
-	@Override
-	public int getMaxLatency() {
-		return maxLatency;
-	}
-
-	@Override
-	public int getMaxIdleTime() {
-		// Bluetooth detects dead connections so we don't need keepalives
-		return Integer.MAX_VALUE;
-	}
-
-	@Override
-	public void start() throws PluginException {
-		if (used.getAndSet(true)) throw new IllegalStateException();
-		// BluetoothAdapter.getDefaultAdapter() must be called on a thread
-		// with a message queue, so submit it to the AndroidExecutor
-		try {
-			adapter = androidExecutor.runOnBackgroundThread(
-					BluetoothAdapter::getDefaultAdapter).get();
-		} catch (InterruptedException e) {
-			Thread.currentThread().interrupt();
-			LOG.warning("Interrupted while getting BluetoothAdapter");
-			throw new PluginException(e);
-		} catch (ExecutionException e) {
-			throw new PluginException(e);
-		}
-		if (adapter == null) {
-			LOG.info("Bluetooth is not supported");
-			throw new PluginException();
-		}
-		running = true;
-		// Listen for changes to the Bluetooth state
-		IntentFilter filter = new IntentFilter();
-		filter.addAction(ACTION_STATE_CHANGED);
-		filter.addAction(ACTION_SCAN_MODE_CHANGED);
-		receiver = new BluetoothStateReceiver();
-		appContext.registerReceiver(receiver, filter);
-		// If Bluetooth is enabled, bind a socket
-		if (adapter.isEnabled()) {
-			bind();
-		} else {
-			// Enable Bluetooth if settings allow
-			if (callback.getSettings().getBoolean(PREF_BT_ENABLE, false)) {
-				enableAdapter();
-			} else {
-				LOG.info("Not enabling Bluetooth");
-			}
-		}
-	}
-
-	private void bind() {
-		ioExecutor.execute(() -> {
-			if (!isRunning()) return;
-			String address = AndroidUtils.getBluetoothAddress(appContext,
-					adapter);
-			if (LOG.isLoggable(INFO))
-				LOG.info("Local address " + scrubMacAddress(address));
-			if (!StringUtils.isNullOrEmpty(address)) {
-				// Advertise the Bluetooth address to contacts
-				TransportProperties p = new TransportProperties();
-				p.put(PROP_ADDRESS, address);
-				callback.mergeLocalProperties(p);
-			}
-			// Bind a server socket to accept connections from contacts
-			BluetoothServerSocket ss;
-			try {
-				ss = adapter.listenUsingInsecureRfcommWithServiceRecord(
-						"RFCOMM", getUuid());
-			} catch (IOException e) {
-				if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
-				return;
-			}
-			if (!isRunning()) {
-				tryToClose(ss);
-				return;
-			}
-			LOG.info("Socket bound");
-			socket = ss;
-			backoff.reset();
-			callback.transportEnabled();
-			acceptContactConnections();
-		});
-	}
-
-	private UUID getUuid() {
-		String uuid = callback.getLocalProperties().get(PROP_UUID);
-		if (uuid == null) {
-			byte[] random = new byte[UUID_BYTES];
-			secureRandom.nextBytes(random);
-			uuid = UUID.nameUUIDFromBytes(random).toString();
-			TransportProperties p = new TransportProperties();
-			p.put(PROP_UUID, uuid);
-			callback.mergeLocalProperties(p);
-		}
-		return UUID.fromString(uuid);
-	}
-
-	private void tryToClose(@Nullable BluetoothServerSocket ss) {
-		try {
-			if (ss != null) ss.close();
-		} catch (IOException e) {
-			if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
-		} finally {
-			callback.transportDisabled();
-		}
-	}
-
-	private void acceptContactConnections() {
-		while (isRunning()) {
-			BluetoothSocket s;
-			try {
-				s = socket.accept();
-			} catch (IOException e) {
-				// This is expected when the socket is closed
-				if (LOG.isLoggable(INFO)) LOG.info(e.toString());
-				return;
-			}
-			if (LOG.isLoggable(INFO)) {
-				String address = s.getRemoteDevice().getAddress();
-				LOG.info("Connection from " + scrubMacAddress(address));
-			}
-			backoff.reset();
-			callback.incomingConnectionCreated(wrapSocket(s));
-		}
-	}
-
-	private DuplexTransportConnection wrapSocket(BluetoothSocket s) {
-		return new DroidtoothTransportConnection(this, s);
-	}
-
-	private void enableAdapter() {
-		if (adapter != null && !adapter.isEnabled()) {
-			if (adapter.enable()) {
-				LOG.info("Enabling Bluetooth");
-				wasEnabledByUs = true;
-			} else {
-				LOG.info("Could not enable Bluetooth");
-			}
-		}
-	}
-
-	@Override
-	public void stop() {
-		running = false;
-		if (receiver != null) appContext.unregisterReceiver(receiver);
-		tryToClose(socket);
-		disableAdapter();
-	}
-
-	private void disableAdapter() {
-		if (adapter != null && adapter.isEnabled() && wasEnabledByUs) {
-			if (adapter.disable()) LOG.info("Disabling Bluetooth");
-			else LOG.info("Could not disable Bluetooth");
-		}
-	}
-
-	@Override
-	public boolean isRunning() {
-		return running && adapter != null && adapter.isEnabled();
-	}
-
-	@Override
-	public boolean shouldPoll() {
-		return true;
-	}
-
-	@Override
-	public int getPollingInterval() {
-		return backoff.getPollingInterval();
-	}
-
-	@Override
-	public void poll(Collection<ContactId> connected) {
-		if (!isRunning()) return;
-		backoff.increment();
-		// Try to connect to known devices in parallel
-		Map<ContactId, TransportProperties> remote =
-				callback.getRemoteProperties();
-		for (Entry<ContactId, TransportProperties> e : remote.entrySet()) {
-			ContactId c = e.getKey();
-			if (connected.contains(c)) continue;
-			String address = e.getValue().get(PROP_ADDRESS);
-			if (StringUtils.isNullOrEmpty(address)) continue;
-			String uuid = e.getValue().get(PROP_UUID);
-			if (StringUtils.isNullOrEmpty(uuid)) continue;
-			ioExecutor.execute(() -> {
-				if (!running) return;
-				BluetoothSocket s = connect(address, uuid);
-				if (s != null) {
-					backoff.reset();
-					callback.outgoingConnectionCreated(c, wrapSocket(s));
-				}
-			});
-		}
-	}
-
-	@Nullable
-	private BluetoothSocket connect(String address, String uuid) {
-		// Validate the address
-		if (!BluetoothAdapter.checkBluetoothAddress(address)) {
-			if (LOG.isLoggable(WARNING))
-				// not scrubbing here to be able to figure out the problem
-				LOG.warning("Invalid address " + address);
-			return null;
-		}
-		// Validate the UUID
-		UUID u;
-		try {
-			u = UUID.fromString(uuid);
-		} catch (IllegalArgumentException e) {
-			if (LOG.isLoggable(WARNING)) LOG.warning("Invalid UUID " + uuid);
-			return null;
-		}
-		// Try to connect
-		BluetoothDevice d = adapter.getRemoteDevice(address);
-		BluetoothSocket s = null;
-		try {
-			s = d.createInsecureRfcommSocketToServiceRecord(u);
-			if (LOG.isLoggable(INFO))
-				LOG.info("Connecting to " + scrubMacAddress(address));
-			s.connect();
-			if (LOG.isLoggable(INFO))
-				LOG.info("Connected to " + scrubMacAddress(address));
-			return s;
-		} catch (IOException e) {
-			if (LOG.isLoggable(INFO)) {
-				LOG.info("Failed to connect to " + scrubMacAddress(address)
-						+ ": " + e);
-			}
-			tryToClose(s);
-			return null;
-		}
-	}
-
-	private void tryToClose(@Nullable Closeable c) {
-		try {
-			if (c != null) c.close();
-		} catch (IOException e) {
-			if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
-		}
-	}
-
-	@Override
-	public DuplexTransportConnection createConnection(ContactId c) {
-		if (!isRunning()) return null;
-		TransportProperties p = callback.getRemoteProperties(c);
-		String address = p.get(PROP_ADDRESS);
-		if (StringUtils.isNullOrEmpty(address)) return null;
-		String uuid = p.get(PROP_UUID);
-		if (StringUtils.isNullOrEmpty(uuid)) return null;
-		BluetoothSocket s = connect(address, uuid);
-		if (s == null) return null;
-		return new DroidtoothTransportConnection(this, s);
-	}
-
-	@Override
-	public boolean supportsKeyAgreement() {
-		return true;
-	}
-
-	@Override
-	public KeyAgreementListener createKeyAgreementListener(byte[] commitment) {
-		if (!isRunning()) return null;
-		// There's no point listening if we can't discover our own address
-		String address = AndroidUtils.getBluetoothAddress(appContext, adapter);
-		if (address.isEmpty()) return null;
-		// No truncation necessary because COMMIT_LENGTH = 16
-		UUID uuid = UUID.nameUUIDFromBytes(commitment);
-		if (LOG.isLoggable(INFO)) LOG.info("Key agreement UUID " + uuid);
-		// Bind a server socket for receiving key agreement connections
-		BluetoothServerSocket ss;
-		try {
-			ss = adapter.listenUsingInsecureRfcommWithServiceRecord(
-					"RFCOMM", uuid);
-		} catch (IOException e) {
-			if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
-			return null;
-		}
-		BdfList descriptor = new BdfList();
-		descriptor.add(TRANSPORT_ID_BLUETOOTH);
-		descriptor.add(StringUtils.macToBytes(address));
-		return new BluetoothKeyAgreementListener(descriptor, ss);
-	}
-
-	@Override
-	public DuplexTransportConnection createKeyAgreementConnection(
-			byte[] commitment, BdfList descriptor, long timeout) {
-		if (!isRunning()) return null;
-		String address;
-		try {
-			address = parseAddress(descriptor);
-		} catch (FormatException e) {
-			LOG.info("Invalid address in key agreement descriptor");
-			return null;
-		}
-		// No truncation necessary because COMMIT_LENGTH = 16
-		UUID uuid = UUID.nameUUIDFromBytes(commitment);
-		if (LOG.isLoggable(INFO))
-			LOG.info("Connecting to key agreement UUID " + uuid);
-		BluetoothSocket s = connect(address, uuid.toString());
-		if (s == null) return null;
-		return new DroidtoothTransportConnection(this, s);
-	}
-
-	private String parseAddress(BdfList descriptor) throws FormatException {
-		byte[] mac = descriptor.getRaw(1);
-		if (mac.length != 6) throw new FormatException();
-		return StringUtils.macToString(mac);
-	}
-
-	@Override
-	public void eventOccurred(Event e) {
-		if (e instanceof EnableBluetoothEvent) {
-			enableAdapterAsync();
-		} else if (e instanceof DisableBluetoothEvent) {
-			disableAdapterAsync();
-		}
-	}
-
-	private void enableAdapterAsync() {
-		ioExecutor.execute(this::enableAdapter);
-	}
-
-	private void disableAdapterAsync() {
-		ioExecutor.execute(this::disableAdapter);
-	}
-
-	private class BluetoothStateReceiver extends BroadcastReceiver {
-
-		@Override
-		public void onReceive(Context ctx, Intent intent) {
-			int state = intent.getIntExtra(EXTRA_STATE, 0);
-			if (state == STATE_ON) {
-				LOG.info("Bluetooth enabled");
-				bind();
-			} else if (state == STATE_OFF) {
-				LOG.info("Bluetooth disabled");
-				tryToClose(socket);
-			}
-			int scanMode = intent.getIntExtra(EXTRA_SCAN_MODE, 0);
-			if (scanMode == SCAN_MODE_NONE) {
-				LOG.info("Scan mode: None");
-			} else if (scanMode == SCAN_MODE_CONNECTABLE) {
-				LOG.info("Scan mode: Connectable");
-			} else if (scanMode == SCAN_MODE_CONNECTABLE_DISCOVERABLE) {
-				LOG.info("Scan mode: Discoverable");
-			}
-		}
-	}
-
-	private class BluetoothKeyAgreementListener extends KeyAgreementListener {
-
-		private final BluetoothServerSocket ss;
-
-		private BluetoothKeyAgreementListener(BdfList descriptor,
-				BluetoothServerSocket ss) {
-			super(descriptor);
-			this.ss = ss;
-		}
-
-		@Override
-		public Callable<KeyAgreementConnection> listen() {
-			return () -> {
-				BluetoothSocket s = ss.accept();
-				if (LOG.isLoggable(INFO))
-					LOG.info(ID.getString() + ": Incoming connection");
-				return new KeyAgreementConnection(
-						new DroidtoothTransportConnection(
-								DroidtoothPlugin.this, s), ID);
-			};
-		}
-
-		@Override
-		public void close() {
-			try {
-				ss.close();
-			} catch (IOException e) {
-				if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
-			}
-		}
-	}
-}

bramble-android/src/main/java/org/briarproject/bramble/plugin/tcp/AndroidLanTcpPlugin.java

@@ -5,37 +5,84 @@ import android.content.Context;
 import android.content.Intent;
 import android.content.IntentFilter;
 import android.net.ConnectivityManager;
+import android.net.Network;
 import android.net.NetworkInfo;
+import android.net.wifi.WifiInfo;
+import android.net.wifi.WifiManager;
 
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.Backoff;
 import org.briarproject.bramble.api.plugin.duplex.DuplexPluginCallback;
 
+import java.io.IOException;
+import java.net.InetAddress;
+import java.net.Socket;
+import java.net.UnknownHostException;
+import java.util.Collection;
 import java.util.concurrent.Executor;
+import java.util.concurrent.ScheduledExecutorService;
 import java.util.logging.Logger;
 
 import javax.annotation.Nullable;
+import javax.net.SocketFactory;
 
 import static android.content.Context.CONNECTIVITY_SERVICE;
+import static android.content.Context.WIFI_SERVICE;
 import static android.net.ConnectivityManager.CONNECTIVITY_ACTION;
 import static android.net.ConnectivityManager.TYPE_WIFI;
+import static android.net.wifi.WifiManager.EXTRA_WIFI_STATE;
+import static android.os.Build.VERSION.SDK_INT;
+import static java.util.Collections.emptyList;
+import static java.util.Collections.singletonList;
+import static java.util.concurrent.TimeUnit.SECONDS;
 
 @NotNullByDefault
 class AndroidLanTcpPlugin extends LanTcpPlugin {
 
+	// See android.net.wifi.WifiManager
+	private static final String WIFI_AP_STATE_CHANGED_ACTION =
+			"android.net.wifi.WIFI_AP_STATE_CHANGED";
+	private static final int WIFI_AP_STATE_ENABLED = 13;
+
+	private static final byte[] WIFI_AP_ADDRESS_BYTES =
+			{(byte) 192, (byte) 168, 43, 1};
+	private static final InetAddress WIFI_AP_ADDRESS;
+
 	private static final Logger LOG =
 			Logger.getLogger(AndroidLanTcpPlugin.class.getName());
 
+	static {
+		try {
+			WIFI_AP_ADDRESS = InetAddress.getByAddress(WIFI_AP_ADDRESS_BYTES);
+		} catch (UnknownHostException e) {
+			// Should only be thrown if the address has an illegal length
+			throw new AssertionError(e);
+		}
+	}
+
+	private final ScheduledExecutorService scheduler;
 	private final Context appContext;
+	private final ConnectivityManager connectivityManager;
+	@Nullable
+	private final WifiManager wifiManager;
 
 	@Nullable
 	private volatile BroadcastReceiver networkStateReceiver = null;
+	private volatile SocketFactory socketFactory;
 
-	AndroidLanTcpPlugin(Executor ioExecutor, Backoff backoff,
-			Context appContext, DuplexPluginCallback callback, int maxLatency,
-			int maxIdleTime) {
+	AndroidLanTcpPlugin(Executor ioExecutor, ScheduledExecutorService scheduler,
+			Backoff backoff, Context appContext, DuplexPluginCallback callback,
+			int maxLatency, int maxIdleTime) {
 		super(ioExecutor, backoff, callback, maxLatency, maxIdleTime);
+		this.scheduler = scheduler;
 		this.appContext = appContext;
+		ConnectivityManager connectivityManager = (ConnectivityManager)
+				appContext.getSystemService(CONNECTIVITY_SERVICE);
+		if (connectivityManager == null) throw new AssertionError();
+		this.connectivityManager = connectivityManager;
+		wifiManager = (WifiManager) appContext.getApplicationContext()
+				.getSystemService(WIFI_SERVICE);
+		socketFactory = SocketFactory.getDefault();
 	}
 
 	@Override
@@ -44,7 +91,9 @@ class AndroidLanTcpPlugin extends LanTcpPlugin {
 		running = true;
 		// Register to receive network status events
 		networkStateReceiver = new NetworkStateReceiver();
-		IntentFilter filter = new IntentFilter(CONNECTIVITY_ACTION);
+		IntentFilter filter = new IntentFilter();
+		filter.addAction(CONNECTIVITY_ACTION);
+		filter.addAction(WIFI_AP_STATE_CHANGED_ACTION);
 		appContext.registerReceiver(networkStateReceiver, filter);
 	}
 
@@ -56,21 +105,92 @@ class AndroidLanTcpPlugin extends LanTcpPlugin {
 		tryToClose(socket);
 	}
 
+	@Override
+	protected Socket createSocket() throws IOException {
+		return socketFactory.createSocket();
+	}
+
+	@Override
+	protected Collection<InetAddress> getLocalIpAddresses() {
+		// If the device doesn't have wifi, don't open any sockets
+		if (wifiManager == null) return emptyList();
+		// If we're connected to a wifi network, use that network
+		WifiInfo info = wifiManager.getConnectionInfo();
+		if (info != null && info.getIpAddress() != 0)
+			return singletonList(intToInetAddress(info.getIpAddress()));
+		// If we're running an access point, return its address
+		if (super.getLocalIpAddresses().contains(WIFI_AP_ADDRESS))
+				return singletonList(WIFI_AP_ADDRESS);
+		// No suitable addresses
+		return emptyList();
+	}
+
+	private InetAddress intToInetAddress(int ip) {
+		byte[] ipBytes = new byte[4];
+		ipBytes[0] = (byte) (ip & 0xFF);
+		ipBytes[1] = (byte) ((ip >> 8) & 0xFF);
+		ipBytes[2] = (byte) ((ip >> 16) & 0xFF);
+		ipBytes[3] = (byte) ((ip >> 24) & 0xFF);
+		try {
+			return InetAddress.getByAddress(ipBytes);
+		} catch (UnknownHostException e) {
+			// Should only be thrown if address has illegal length
+			throw new AssertionError(e);
+		}
+	}
+
+	// On API 21 and later, a socket that is not created with the wifi
+	// network's socket factory may try to connect via another network
+	private SocketFactory getSocketFactory() {
+		if (SDK_INT < 21) return SocketFactory.getDefault();
+		for (Network net : connectivityManager.getAllNetworks()) {
+			NetworkInfo info = connectivityManager.getNetworkInfo(net);
+			if (info != null && info.getType() == TYPE_WIFI)
+				return net.getSocketFactory();
+		}
+		LOG.warning("Could not find suitable socket factory");
+		return SocketFactory.getDefault();
+	}
+
 	private class NetworkStateReceiver extends BroadcastReceiver {
 
 		@Override
 		public void onReceive(Context ctx, Intent i) {
 			if (!running) return;
-			Object o = ctx.getSystemService(CONNECTIVITY_SERVICE);
-			ConnectivityManager cm = (ConnectivityManager) o;
-			NetworkInfo net = cm.getActiveNetworkInfo();
-			if (net != null && net.getType() == TYPE_WIFI && net.isConnected()) {
-				LOG.info("Connected to Wi-Fi");
-				if (socket == null || socket.isClosed()) bind();
+			if (isApEnabledEvent(i)) {
+				// The state change may be broadcast before the AP address is
+				// visible, so delay handling the event
+				scheduler.schedule(this::handleConnectivityChange, 1, SECONDS);
 			} else {
-				LOG.info("Not connected to Wi-Fi");
-				tryToClose(socket);
+				handleConnectivityChange();
 			}
 		}
+
+		private void handleConnectivityChange() {
+			if (!running) return;
+			Collection<InetAddress> addrs = getLocalIpAddresses();
+			if (addrs.contains(WIFI_AP_ADDRESS)) {
+				LOG.info("Providing wifi hotspot");
+				// There's no corresponding Network object and thus no way
+				// to get a suitable socket factory, so we won't be able to
+				// make outgoing connections on API 21+ if another network
+				// has internet access
+				socketFactory = SocketFactory.getDefault();
+				if (socket == null || socket.isClosed()) bind();
+			} else if (addrs.isEmpty()) {
+				LOG.info("Not connected to wifi");
+				socketFactory = SocketFactory.getDefault();
+				tryToClose(socket);
+			} else {
+				LOG.info("Connected to wifi");
+				socketFactory = getSocketFactory();
+				if (socket == null || socket.isClosed()) bind();
+			}
+		}
+
+		private boolean isApEnabledEvent(Intent i) {
+			return WIFI_AP_STATE_CHANGED_ACTION.equals(i.getAction()) &&
+					i.getIntExtra(EXTRA_WIFI_STATE, 0) == WIFI_AP_STATE_ENABLED;
+		}
 	}
 }

bramble-android/src/main/java/org/briarproject/bramble/plugin/tcp/AndroidLanTcpPluginFactory.java

@@ -11,6 +11,7 @@ import org.briarproject.bramble.api.plugin.duplex.DuplexPluginCallback;
 import org.briarproject.bramble.api.plugin.duplex.DuplexPluginFactory;
 
 import java.util.concurrent.Executor;
+import java.util.concurrent.ScheduledExecutorService;
 
 import javax.annotation.concurrent.Immutable;
 
@@ -27,12 +28,15 @@ public class AndroidLanTcpPluginFactory implements DuplexPluginFactory {
 	private static final double BACKOFF_BASE = 1.2;
 
 	private final Executor ioExecutor;
+	private final ScheduledExecutorService scheduler;
 	private final BackoffFactory backoffFactory;
 	private final Context appContext;
 
 	public AndroidLanTcpPluginFactory(Executor ioExecutor,
-			BackoffFactory backoffFactory, Context appContext) {
+			ScheduledExecutorService scheduler, BackoffFactory backoffFactory,
+			Context appContext) {
 		this.ioExecutor = ioExecutor;
+		this.scheduler = scheduler;
 		this.backoffFactory = backoffFactory;
 		this.appContext = appContext;
 	}
@@ -51,7 +55,7 @@ public class AndroidLanTcpPluginFactory implements DuplexPluginFactory {
 	public DuplexPlugin createPlugin(DuplexPluginCallback callback) {
 		Backoff backoff = backoffFactory.createBackoff(MIN_POLLING_INTERVAL,
 				MAX_POLLING_INTERVAL, BACKOFF_BASE);
-		return new AndroidLanTcpPlugin(ioExecutor, backoff, appContext,
-				callback, MAX_LATENCY, MAX_IDLE_TIME);
+		return new AndroidLanTcpPlugin(ioExecutor, scheduler, backoff,
+				appContext, callback, MAX_LATENCY, MAX_IDLE_TIME);
 	}
 }

bramble-android/src/main/java/org/briarproject/bramble/plugin/tor/TorPlugin.java

@@ -16,6 +16,7 @@ import android.os.PowerManager;
 import net.freehaven.tor.control.EventHandler;
 import net.freehaven.tor.control.TorControlConnection;
 
+import org.briarproject.bramble.PoliteExecutor;
 import org.briarproject.bramble.api.contact.ContactId;
 import org.briarproject.bramble.api.data.BdfList;
 import org.briarproject.bramble.api.event.Event;
@@ -59,7 +60,10 @@ import java.util.Map.Entry;
 import java.util.Scanner;
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.Executor;
+import java.util.concurrent.Future;
+import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.concurrent.atomic.AtomicReference;
 import java.util.logging.Logger;
 import java.util.regex.Pattern;
 import java.util.zip.ZipInputStream;
@@ -70,10 +74,15 @@ import javax.net.SocketFactory;
 import static android.content.Context.CONNECTIVITY_SERVICE;
 import static android.content.Context.MODE_PRIVATE;
 import static android.content.Context.POWER_SERVICE;
+import static android.content.Intent.ACTION_SCREEN_OFF;
+import static android.content.Intent.ACTION_SCREEN_ON;
 import static android.net.ConnectivityManager.CONNECTIVITY_ACTION;
 import static android.net.ConnectivityManager.TYPE_WIFI;
+import static android.os.Build.VERSION.SDK_INT;
+import static android.os.PowerManager.ACTION_DEVICE_IDLE_MODE_CHANGED;
 import static android.os.PowerManager.PARTIAL_WAKE_LOCK;
 import static java.util.concurrent.TimeUnit.MILLISECONDS;
+import static java.util.concurrent.TimeUnit.MINUTES;
 import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
 import static net.freehaven.tor.control.TorControlCommands.HS_ADDRESS;
@@ -101,7 +110,8 @@ class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 	private static final Logger LOG =
 			Logger.getLogger(TorPlugin.class.getName());
 
-	private final Executor ioExecutor;
+	private final Executor ioExecutor, connectionStatusExecutor;
+	private final ScheduledExecutorService scheduler;
 	private final Context appContext;
 	private final LocationUtils locationUtils;
 	private final DevReporter reporter;
@@ -114,6 +124,8 @@ class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 	private final File torDirectory, torFile, geoIpFile, configFile;
 	private final File doneFile, cookieFile;
 	private final PowerManager.WakeLock wakeLock;
+	private final AtomicReference<Future<?>> connectivityCheck =
+			new AtomicReference<>();
 	private final AtomicBoolean used = new AtomicBoolean(false);
 
 	private volatile boolean running = false;
@@ -122,12 +134,13 @@ class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 	private volatile TorControlConnection controlConnection = null;
 	private volatile BroadcastReceiver networkStateReceiver = null;
 
-	TorPlugin(Executor ioExecutor, Context appContext,
-			LocationUtils locationUtils, DevReporter reporter,
-			SocketFactory torSocketFactory, Backoff backoff,
-			DuplexPluginCallback callback, String architecture, int maxLatency,
-			int maxIdleTime) {
+	TorPlugin(Executor ioExecutor, ScheduledExecutorService scheduler,
+			Context appContext, LocationUtils locationUtils,
+			DevReporter reporter, SocketFactory torSocketFactory,
+			Backoff backoff, DuplexPluginCallback callback,
+			String architecture, int maxLatency, int maxIdleTime) {
 		this.ioExecutor = ioExecutor;
+		this.scheduler = scheduler;
 		this.appContext = appContext;
 		this.locationUtils = locationUtils;
 		this.reporter = reporter;
@@ -152,6 +165,9 @@ class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 		// This tag will prevent Huawei's powermanager from killing us.
 		wakeLock = pm.newWakeLock(PARTIAL_WAKE_LOCK, "LocationManagerService");
 		wakeLock.setReferenceCounted(false);
+		// Don't execute more than one connection status check at a time
+		connectionStatusExecutor = new PoliteExecutor("TorPlugin",
+				ioExecutor, 1);
 	}
 
 	@Override
@@ -204,11 +220,11 @@ class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 		if (LOG.isLoggable(INFO)) {
 			Scanner stdout = new Scanner(torProcess.getInputStream());
 			Scanner stderr = new Scanner(torProcess.getErrorStream());
-			while (stdout.hasNextLine() || stderr.hasNextLine()){
-				if(stdout.hasNextLine()) {
+			while (stdout.hasNextLine() || stderr.hasNextLine()) {
+				if (stdout.hasNextLine()) {
 					LOG.info(stdout.nextLine());
 				}
-				if(stderr.hasNextLine()){
+				if (stderr.hasNextLine()) {
 					LOG.info(stderr.nextLine());
 				}
 			}
@@ -257,7 +273,11 @@ class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 		}
 		// Register to receive network status events
 		networkStateReceiver = new NetworkStateReceiver();
-		IntentFilter filter = new IntentFilter(CONNECTIVITY_ACTION);
+		IntentFilter filter = new IntentFilter();
+		filter.addAction(CONNECTIVITY_ACTION);
+		filter.addAction(ACTION_SCREEN_ON);
+		filter.addAction(ACTION_SCREEN_OFF);
+		if (SDK_INT >= 23) filter.addAction(ACTION_DEVICE_IDLE_MODE_CHANGED);
 		appContext.registerReceiver(networkStateReceiver, filter);
 		// Bind a server socket to receive incoming hidden service connections
 		bind();
@@ -594,7 +614,7 @@ class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 
 	@Override
 	public DuplexTransportConnection createKeyAgreementConnection(
-			byte[] commitment, BdfList descriptor, long timeout) {
+			byte[] commitment, BdfList descriptor) {
 		throw new UnsupportedOperationException();
 	}
 
@@ -618,6 +638,8 @@ class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 	@Override
 	public void orConnStatus(String status, String orName) {
 		if (LOG.isLoggable(INFO)) LOG.info("OR connection " + status);
+		if (status.equals("CLOSED") || status.equals("FAILED"))
+			updateConnectionStatus(); // Check whether we've lost connectivity
 	}
 
 	@Override
@@ -657,7 +679,7 @@ class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 		}
 
 		@Override
-		public void onEvent(int event, String path) {
+		public void onEvent(int event, @Nullable String path) {
 			stopWatching();
 			latch.countDown();
 		}
@@ -675,9 +697,8 @@ class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 	}
 
 	private void updateConnectionStatus() {
-		ioExecutor.execute(() -> {
+		connectionStatusExecutor.execute(() -> {
 			if (!running) return;
-
 			Object o = appContext.getSystemService(CONNECTIVITY_SERVICE);
 			ConnectivityManager cm = (ConnectivityManager) o;
 			NetworkInfo net = cm.getActiveNetworkInfo();
@@ -716,14 +737,25 @@ class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 		});
 	}
 
+	private void scheduleConnectionStatusUpdate() {
+		Future<?> newConnectivityCheck =
+				scheduler.schedule(this::updateConnectionStatus, 1, MINUTES);
+		Future<?> oldConnectivityCheck =
+				connectivityCheck.getAndSet(newConnectivityCheck);
+		if (oldConnectivityCheck != null) oldConnectivityCheck.cancel(false);
+	}
+
 	private class NetworkStateReceiver extends BroadcastReceiver {
 
 		@Override
 		public void onReceive(Context ctx, Intent i) {
 			if (!running) return;
-			if (CONNECTIVITY_ACTION.equals(i.getAction())) {
-				LOG.info("Detected connectivity change");
-				updateConnectionStatus();
+			String action = i.getAction();
+			if (LOG.isLoggable(INFO)) LOG.info("Received broadcast " + action);
+			updateConnectionStatus();
+			if (ACTION_SCREEN_ON.equals(action)
+					|| ACTION_SCREEN_OFF.equals(action)) {
+				scheduleConnectionStatusUpdate();
 			}
 		}
 	}

bramble-android/src/main/java/org/briarproject/bramble/plugin/tor/TorPluginFactory.java

@@ -17,6 +17,7 @@ import org.briarproject.bramble.api.system.LocationUtils;
 import org.briarproject.bramble.util.AndroidUtils;
 
 import java.util.concurrent.Executor;
+import java.util.concurrent.ScheduledExecutorService;
 import java.util.logging.Logger;
 
 import javax.annotation.concurrent.Immutable;
@@ -36,6 +37,7 @@ public class TorPluginFactory implements DuplexPluginFactory {
 	private static final double BACKOFF_BASE = 1.2;
 
 	private final Executor ioExecutor;
+	private final ScheduledExecutorService scheduler;
 	private final Context appContext;
 	private final LocationUtils locationUtils;
 	private final DevReporter reporter;
@@ -43,11 +45,13 @@ public class TorPluginFactory implements DuplexPluginFactory {
 	private final SocketFactory torSocketFactory;
 	private final BackoffFactory backoffFactory;
 
-	public TorPluginFactory(Executor ioExecutor, Context appContext,
+	public TorPluginFactory(Executor ioExecutor,
+			ScheduledExecutorService scheduler, Context appContext,
 			LocationUtils locationUtils, DevReporter reporter,
 			EventBus eventBus, SocketFactory torSocketFactory,
 			BackoffFactory backoffFactory) {
 		this.ioExecutor = ioExecutor;
+		this.scheduler = scheduler;
 		this.appContext = appContext;
 		this.locationUtils = locationUtils;
 		this.reporter = reporter;
@@ -89,9 +93,9 @@ public class TorPluginFactory implements DuplexPluginFactory {
 
 		Backoff backoff = backoffFactory.createBackoff(MIN_POLLING_INTERVAL,
 				MAX_POLLING_INTERVAL, BACKOFF_BASE);
-		TorPlugin plugin = new TorPlugin(ioExecutor, appContext, locationUtils,
-				reporter, torSocketFactory, backoff, callback, architecture,
-				MAX_LATENCY, MAX_IDLE_TIME);
+		TorPlugin plugin = new TorPlugin(ioExecutor, scheduler, appContext,
+				locationUtils, reporter, torSocketFactory, backoff, callback,
+				architecture, MAX_LATENCY, MAX_IDLE_TIME);
 		eventBus.addListener(plugin);
 		return plugin;
 	}

bramble-api/src/main/java/org/briarproject/bramble/api/db/DataTooNewException.java

@@ -0,0 +1,7 @@
+package org.briarproject.bramble.api.db;
+
+/**
+ * Thrown when the database uses a newer schema than the current code.
+ */
+public class DataTooNewException extends DbException {
+}

bramble-api/src/main/java/org/briarproject/bramble/api/db/DataTooOldException.java

@@ -0,0 +1,8 @@
+package org.briarproject.bramble.api.db;
+
+/**
+ * Thrown when the database uses an older schema than the current code and
+ * cannot be migrated.
+ */
+public class DataTooOldException extends DbException {
+}

bramble-api/src/main/java/org/briarproject/bramble/api/db/DatabaseComponent.java

@@ -37,8 +37,13 @@ public interface DatabaseComponent {
 
 	/**
 	 * Opens the database and returns true if the database already existed.
+	 *
+	 * @throws DataTooNewException if the data uses a newer schema than the
+	 * current code
+	 * @throws DataTooOldException if the data uses an older schema than the
+	 * current code and cannot be migrated
 	 */
-	boolean open() throws DbException;
+	boolean open(@Nullable MigrationListener listener) throws DbException;
 
 	/**
 	 * Waits for any open transactions to finish and closes the database.
@@ -254,31 +259,30 @@ public interface DatabaseComponent {
 	Collection<LocalAuthor> getLocalAuthors(Transaction txn) throws DbException;
 
 	/**
-	 * Returns the IDs of any messages that need to be validated by the given
-	 * client.
+	 * Returns the IDs of any messages that need to be validated.
 	 * <p/>
 	 * Read-only.
 	 */
-	Collection<MessageId> getMessagesToValidate(Transaction txn, ClientId c)
+	Collection<MessageId> getMessagesToValidate(Transaction txn)
 			throws DbException;
 
 	/**
-	 * Returns the IDs of any messages that are valid but pending delivery due
-	 * to dependencies on other messages for the given client.
+	 * Returns the IDs of any messages that are pending delivery due to
+	 * dependencies on other messages.
 	 * <p/>
 	 * Read-only.
 	 */
-	Collection<MessageId> getPendingMessages(Transaction txn, ClientId c)
+	Collection<MessageId> getPendingMessages(Transaction txn)
 			throws DbException;
 
 	/**
-	 * Returns the IDs of any messages from the given client
-	 * that have a shared dependent, but are still not shared themselves.
+	 * Returns the IDs of any messages that have shared dependents but have
+	 * not yet been shared themselves.
 	 * <p/>
 	 * Read-only.
 	 */
-	Collection<MessageId> getMessagesToShare(Transaction txn,
-			ClientId c) throws DbException;
+	Collection<MessageId> getMessagesToShare(Transaction txn)
+			throws DbException;
 
 	/**
 	 * Returns the message with the given ID, in serialised form, or null if
@@ -373,6 +377,16 @@ public interface DatabaseComponent {
 	MessageStatus getMessageStatus(Transaction txn, ContactId c, MessageId m)
 			throws DbException;
 
+	/*
+	 * Returns the next time (in milliseconds since the Unix epoch) when a
+	 * message is due to be sent to the given contact. The returned value may
+	 * be zero if a message is due to be sent immediately, or Long.MAX_VALUE if
+	 * no messages are scheduled to be sent.
+	 * <p/>
+	 * Read-only.
+	 */
+	long getNextSendTime(Transaction txn, ContactId c) throws DbException;
+
 	/**
 	 * Returns all settings in the given namespace.
 	 * <p/>

bramble-api/src/main/java/org/briarproject/bramble/api/db/MigrationListener.java

@@ -0,0 +1,11 @@
+package org.briarproject.bramble.api.db;
+
+public interface MigrationListener {
+
+	/**
+	 * This is called when a migration is started while opening the database.
+	 * It will be called once for each migration being applied.
+	 */
+	void onMigrationRun();
+
+}

bramble-api/src/main/java/org/briarproject/bramble/api/keyagreement/KeyAgreementListener.java

@@ -2,7 +2,7 @@ package org.briarproject.bramble.api.keyagreement;
 
 import org.briarproject.bramble.api.data.BdfList;
 
-import java.util.concurrent.Callable;
+import java.io.IOException;
 
 /**
  * An class for managing a particular key agreement listener.
@@ -24,11 +24,11 @@ public abstract class KeyAgreementListener {
 	}
 
 	/**
-	 * Starts listening for incoming connections, and returns a Callable that
-	 * will return a KeyAgreementConnection when an incoming connection is
-	 * received.
+	 * Blocks until an incoming connection is received and returns it.
+	 *
+	 * @throws IOException if an error occurs or {@link #close()} is called.
 	 */
-	public abstract Callable<KeyAgreementConnection> listen();
+	public abstract KeyAgreementConnection accept() throws IOException;
 
 	/**
 	 * Closes the underlying server socket.

bramble-api/src/main/java/org/briarproject/bramble/api/lifecycle/LifecycleManager.java

@@ -21,7 +21,25 @@ public interface LifecycleManager {
 	 * The result of calling {@link #startServices(String)}.
 	 */
 	enum StartResult {
-		ALREADY_RUNNING, DB_ERROR, SERVICE_ERROR, SUCCESS
+		ALREADY_RUNNING,
+		DB_ERROR,
+		DATA_TOO_OLD_ERROR,
+		DATA_TOO_NEW_ERROR,
+		SERVICE_ERROR,
+		SUCCESS
+	}
+
+	/**
+	 * The state the lifecycle can be in.
+	 * Returned by {@link #getLifecycleState()}
+	 */
+	enum LifecycleState {
+
+		STARTING, MIGRATING_DATABASE, STARTING_SERVICES, RUNNING, STOPPING;
+
+		public boolean isAfter(LifecycleState state) {
+			return ordinal() > state.ordinal();
+		}
 	}
 
 	/**
@@ -71,4 +89,10 @@ public interface LifecycleManager {
 	 * the {@link DatabaseComponent} to be closed before returning.
 	 */
 	void waitForShutdown() throws InterruptedException;
+
+	/**
+	 * Returns the current state of the lifecycle.
+	 */
+	LifecycleState getLifecycleState();
+
 }

bramble-api/src/main/java/org/briarproject/bramble/api/lifecycle/event/LifecycleEvent.java

@@ -0,0 +1,20 @@
+package org.briarproject.bramble.api.lifecycle.event;
+
+import org.briarproject.bramble.api.event.Event;
+import org.briarproject.bramble.api.lifecycle.LifecycleManager.LifecycleState;
+
+/**
+ * An event that is broadcast when the app enters a new lifecycle state.
+ */
+public class LifecycleEvent extends Event {
+
+	private final LifecycleState state;
+
+	public LifecycleEvent(LifecycleState state) {
+		this.state = state;
+	}
+
+	public LifecycleState getLifecycleState() {
+		return state;
+	}
+}

bramble-api/src/main/java/org/briarproject/bramble/api/lifecycle/event/ShutdownEvent.java

@@ -1,9 +0,0 @@
-package org.briarproject.bramble.api.lifecycle.event;
-
-import org.briarproject.bramble.api.event.Event;
-
-/**
- * An event that is broadcast when the app is shutting down.
- */
-public class ShutdownEvent extends Event {
-}

bramble-api/src/main/java/org/briarproject/bramble/api/plugin/duplex/DuplexPlugin.java

@@ -36,9 +36,9 @@ public interface DuplexPlugin extends Plugin {
 
 	/**
 	 * Attempts to connect to the remote peer specified in the given descriptor.
-	 * Returns null if no connection can be established within the given time.
+	 * Returns null if no connection can be established.
 	 */
 	@Nullable
 	DuplexTransportConnection createKeyAgreementConnection(
-			byte[] remoteCommitment, BdfList descriptor, long timeout);
+			byte[] remoteCommitment, BdfList descriptor);
 }

bramble-api/src/main/java/org/briarproject/bramble/api/plugin/event/BluetoothEnabledEvent.java

@@ -0,0 +1,15 @@
+package org.briarproject.bramble.api.plugin.event;
+
+import org.briarproject.bramble.api.event.Event;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import javax.annotation.concurrent.Immutable;
+
+/**
+ * An event that informs the Bluetooth plugin that we have enabled the
+ * Bluetooth adapter.
+ */
+@Immutable
+@NotNullByDefault
+public class BluetoothEnabledEvent extends Event {
+}

bramble-api/src/main/java/org/briarproject/bramble/api/plugin/event/EnableBluetoothEvent.java

@@ -6,7 +6,7 @@ import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import javax.annotation.concurrent.Immutable;
 
 /**
- * An event asks the Bluetooth plugin to enable the Bluetooth adapter.
+ * An event that asks the Bluetooth plugin to enable the Bluetooth adapter.
  */
 @Immutable
 @NotNullByDefault

bramble-api/src/main/java/org/briarproject/bramble/util/StringUtils.java

@@ -126,6 +126,10 @@ public class StringUtils {
 		return toUtf8(s).length > maxLength;
 	}
 
+	public static boolean isValidMac(String mac) {
+		return MAC.matcher(mac).matches();
+	}
+
 	public static byte[] macToBytes(String mac) {
 		if (!MAC.matcher(mac).matches()) throw new IllegalArgumentException();
 		return fromHexString(mac.replaceAll(":", ""));

bramble-api/src/test/java/org/briarproject/bramble/test/TestUtils.java

@@ -2,12 +2,27 @@ package org.briarproject.bramble.test;
 
 import org.briarproject.bramble.api.UniqueId;
 import org.briarproject.bramble.api.crypto.SecretKey;
+import org.briarproject.bramble.api.identity.Author;
+import org.briarproject.bramble.api.identity.AuthorId;
+import org.briarproject.bramble.api.identity.LocalAuthor;
+import org.briarproject.bramble.api.sync.ClientId;
+import org.briarproject.bramble.api.sync.Group;
+import org.briarproject.bramble.api.sync.GroupId;
+import org.briarproject.bramble.api.sync.Message;
+import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.bramble.util.IoUtils;
 
 import java.io.File;
 import java.util.Random;
 import java.util.concurrent.atomic.AtomicInteger;
 
+import static org.briarproject.bramble.api.identity.AuthorConstants.MAX_AUTHOR_NAME_LENGTH;
+import static org.briarproject.bramble.api.identity.AuthorConstants.MAX_PUBLIC_KEY_LENGTH;
+import static org.briarproject.bramble.api.sync.SyncConstants.MAX_GROUP_DESCRIPTOR_LENGTH;
+import static org.briarproject.bramble.api.sync.SyncConstants.MAX_MESSAGE_BODY_LENGTH;
+import static org.briarproject.bramble.api.sync.SyncConstants.MESSAGE_HEADER_LENGTH;
+import static org.briarproject.bramble.util.StringUtils.getRandomString;
+
 public class TestUtils {
 
 	private static final AtomicInteger nextTestDir =
@@ -38,4 +53,50 @@ public class TestUtils {
 		return new SecretKey(getRandomBytes(SecretKey.LENGTH));
 	}
 
+	public static LocalAuthor getLocalAuthor() {
+		return getLocalAuthor(1 + random.nextInt(MAX_AUTHOR_NAME_LENGTH));
+	}
+
+	public static LocalAuthor getLocalAuthor(int nameLength) {
+		AuthorId id = new AuthorId(getRandomId());
+		String name = getRandomString(nameLength);
+		byte[] publicKey = getRandomBytes(MAX_PUBLIC_KEY_LENGTH);
+		byte[] privateKey = getRandomBytes(MAX_PUBLIC_KEY_LENGTH);
+		long created = System.currentTimeMillis();
+		return new LocalAuthor(id, name, publicKey, privateKey, created);
+	}
+
+	public static Author getAuthor() {
+		return getAuthor(1 + random.nextInt(MAX_AUTHOR_NAME_LENGTH));
+	}
+
+	public static Author getAuthor(int nameLength) {
+		AuthorId id = new AuthorId(getRandomId());
+		String name = getRandomString(nameLength);
+		byte[] publicKey = getRandomBytes(MAX_PUBLIC_KEY_LENGTH);
+		return new Author(id, name, publicKey);
+	}
+
+	public static Group getGroup(ClientId clientId) {
+		int descriptorLength = 1 + random.nextInt(MAX_GROUP_DESCRIPTOR_LENGTH);
+		return getGroup(clientId, descriptorLength);
+	}
+
+	public static Group getGroup(ClientId clientId, int descriptorLength) {
+		GroupId groupId = new GroupId(getRandomId());
+		byte[] descriptor = getRandomBytes(descriptorLength);
+		return new Group(groupId, clientId, descriptor);
+	}
+
+	public static Message getMessage(GroupId groupId) {
+		int bodyLength = 1 + random.nextInt(MAX_MESSAGE_BODY_LENGTH);
+		return getMessage(groupId, MESSAGE_HEADER_LENGTH + bodyLength);
+	}
+
+	public static Message getMessage(GroupId groupId, int rawLength) {
+		MessageId id = new MessageId(getRandomId());
+		byte[] raw = getRandomBytes(rawLength);
+		long timestamp = System.currentTimeMillis();
+		return new Message(id, groupId, timestamp, raw);
+	}
 }

bramble-core/src/main/java/org/briarproject/bramble/db/Database.java

@@ -2,8 +2,11 @@ package org.briarproject.bramble.db;
 
 import org.briarproject.bramble.api.contact.Contact;
 import org.briarproject.bramble.api.contact.ContactId;
+import org.briarproject.bramble.api.db.DataTooNewException;
+import org.briarproject.bramble.api.db.DataTooOldException;
 import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.db.Metadata;
+import org.briarproject.bramble.api.db.MigrationListener;
 import org.briarproject.bramble.api.identity.Author;
 import org.briarproject.bramble.api.identity.AuthorId;
 import org.briarproject.bramble.api.identity.LocalAuthor;
@@ -37,8 +40,13 @@ interface Database<T> {
 
 	/**
 	 * Opens the database and returns true if the database already existed.
+	 *
+	 * @throws DataTooNewException if the data uses a newer schema than the
+	 * current code
+	 * @throws DataTooOldException if the data uses an older schema than the
+	 * current code and cannot be migrated
 	 */
-	boolean open() throws DbException;
+	boolean open(@Nullable MigrationListener listener) throws DbException;
 
 	/**
 	 * Prevents new transactions from starting, waits for all current
@@ -89,9 +97,12 @@ interface Database<T> {
 
 	/**
 	 * Stores a message.
+	 *
+	 * @param sender the contact from whom the message was received, or null
+	 * if the message was created locally.
 	 */
-	void addMessage(T txn, Message m, State state, boolean shared)
-			throws DbException;
+	void addMessage(T txn, Message m, State state, boolean shared,
+			@Nullable ContactId sender) throws DbException;
 
 	/**
 	 * Adds a dependency between two messages in the given group.
@@ -104,16 +115,6 @@ interface Database<T> {
 	 */
 	void addOfferedMessage(T txn, ContactId c, MessageId m) throws DbException;
 
-	/**
-	 * Initialises the status of the given message with respect to the given
-	 * contact.
-	 *
-	 * @param ack whether the message needs to be acknowledged.
-	 * @param seen whether the contact has seen the message.
-	 */
-	void addStatus(T txn, ContactId c, MessageId m, boolean ack, boolean seen)
-			throws DbException;
-
 	/**
 	 * Stores a transport.
 	 */
@@ -272,7 +273,7 @@ interface Database<T> {
 	 * <p/>
 	 * Read-only.
 	 */
-	Collection<ContactId> getGroupVisibility(T txn, GroupId g)
+	Map<ContactId, Boolean> getGroupVisibility(T txn, GroupId g)
 			throws DbException;
 
 	/**
@@ -423,31 +424,37 @@ interface Database<T> {
 			throws DbException;
 
 	/**
-	 * Returns the IDs of any messages that need to be validated by the given
-	 * client.
+	 * Returns the IDs of any messages that need to be validated.
 	 * <p/>
 	 * Read-only.
 	 */
-	Collection<MessageId> getMessagesToValidate(T txn, ClientId c)
-			throws DbException;
+	Collection<MessageId> getMessagesToValidate(T txn) throws DbException;
 
 	/**
-	 * Returns the IDs of any messages that are still pending due to
-	 * dependencies to other messages for the given client.
+	 * Returns the IDs of any messages that are pending delivery due to
+	 * dependencies on other messages.
 	 * <p/>
 	 * Read-only.
 	 */
-	Collection<MessageId> getPendingMessages(T txn, ClientId c)
-			throws DbException;
+	Collection<MessageId> getPendingMessages(T txn) throws DbException;
 
 	/**
-	 * Returns the IDs of any messages from the given client
-	 * that have a shared dependent, but are still not shared themselves.
+	 * Returns the IDs of any messages that have a shared dependent but have
+	 * not yet been shared themselves.
 	 * <p/>
 	 * Read-only.
 	 */
-	Collection<MessageId> getMessagesToShare(T txn, ClientId c)
-			throws DbException;
+	Collection<MessageId> getMessagesToShare(T txn) throws DbException;
+
+	/**
+	 * Returns the next time (in milliseconds since the Unix epoch) when a
+	 * message is due to be sent to the given contact. The returned value may
+	 * be zero if a message is due to be sent immediately, or Long.MAX_VALUE
+	 * if no messages are scheduled to be sent.
+	 * <p/>
+	 * Read-only.
+	 */
+	long getNextSendTime(T txn, ContactId c) throws DbException;
 
 	/**
 	 * Returns the message with the given ID, in serialised form, or null if
@@ -566,13 +573,6 @@ interface Database<T> {
 	 */
 	void removeMessage(T txn, MessageId m) throws DbException;
 
-	/**
-	 * Removes an offered message that was offered by the given contact, or
-	 * returns false if there is no such message.
-	 */
-	boolean removeOfferedMessage(T txn, ContactId c, MessageId m)
-			throws DbException;
-
 	/**
 	 * Removes the given offered messages that were offered by the given
 	 * contact.
@@ -580,12 +580,6 @@ interface Database<T> {
 	void removeOfferedMessages(T txn, ContactId c,
 			Collection<MessageId> requested) throws DbException;
 
-	/**
-	 * Removes the status of the given message with respect to the given
-	 * contact.
-	 */
-	void removeStatus(T txn, ContactId c, MessageId m) throws DbException;
-
 	/**
 	 * Removes a transport (and all associated state) from the database.
 	 */

bramble-core/src/main/java/org/briarproject/bramble/db/DatabaseComponentImpl.java

@@ -10,6 +10,7 @@ import org.briarproject.bramble.api.db.ContactExistsException;
 import org.briarproject.bramble.api.db.DatabaseComponent;
 import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.db.Metadata;
+import org.briarproject.bramble.api.db.MigrationListener;
 import org.briarproject.bramble.api.db.NoSuchContactException;
 import org.briarproject.bramble.api.db.NoSuchGroupException;
 import org.briarproject.bramble.api.db.NoSuchLocalAuthorException;
@@ -90,8 +91,6 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 	private final ReentrantReadWriteLock lock =
 			new ReentrantReadWriteLock(true);
 
-	private volatile int shutdownHandle = -1;
-
 	@Inject
 	DatabaseComponentImpl(Database<T> db, Class<T> txnClass, EventBus eventBus,
 			ShutdownManager shutdown) {
@@ -102,23 +101,22 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 	}
 
 	@Override
-	public boolean open() throws DbException {
-		Runnable shutdownHook = () -> {
+	public boolean open(@Nullable MigrationListener listener)
+			throws DbException {
+		boolean reopened = db.open(listener);
+		shutdown.addShutdownHook(() -> {
 			try {
 				close();
 			} catch (DbException e) {
 				if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
 			}
-		};
-		boolean reopened = db.open();
-		shutdownHandle = shutdown.addShutdownHook(shutdownHook);
+		});
 		return reopened;
 	}
 
 	@Override
 	public void close() throws DbException {
 		if (closed.getAndSet(true)) return;
-		shutdown.removeShutdownHook(shutdownHandle);
 		db.close();
 	}
 
@@ -217,7 +215,7 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 		if (!db.containsGroup(txn, m.getGroupId()))
 			throw new NoSuchGroupException();
 		if (!db.containsMessage(txn, m.getId())) {
-			addMessage(txn, m, DELIVERED, shared, null);
+			db.addMessage(txn, m, DELIVERED, shared, null);
 			transaction.attach(new MessageAddedEvent(m, null));
 			transaction.attach(new MessageStateChangedEvent(m.getId(), true,
 					DELIVERED));
@@ -226,16 +224,6 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 		db.mergeMessageMetadata(txn, m.getId(), meta);
 	}
 
-	private void addMessage(T txn, Message m, State state, boolean shared,
-			@Nullable ContactId sender) throws DbException {
-		db.addMessage(txn, m, state, shared);
-		for (ContactId c : db.getGroupVisibility(txn, m.getGroupId())) {
-			boolean offered = db.removeOfferedMessage(txn, c, m.getId());
-			boolean seen = offered || (sender != null && c.equals(sender));
-			db.addStatus(txn, c, m.getId(), seen, seen);
-		}
-	}
-
 	@Override
 	public void addTransport(Transaction transaction, TransportId t,
 			int maxLatency) throws DbException {
@@ -467,24 +455,24 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 	}
 
 	@Override
-	public Collection<MessageId> getMessagesToValidate(Transaction transaction,
-			ClientId c) throws DbException {
+	public Collection<MessageId> getMessagesToValidate(Transaction transaction)
+			throws DbException {
 		T txn = unbox(transaction);
-		return db.getMessagesToValidate(txn, c);
+		return db.getMessagesToValidate(txn);
 	}
 
 	@Override
-	public Collection<MessageId> getPendingMessages(Transaction transaction,
-			ClientId c) throws DbException {
+	public Collection<MessageId> getPendingMessages(Transaction transaction)
+			throws DbException {
 		T txn = unbox(transaction);
-		return db.getPendingMessages(txn, c);
+		return db.getPendingMessages(txn);
 	}
 
 	@Override
-	public Collection<MessageId> getMessagesToShare(
-			Transaction transaction, ClientId c) throws DbException {
+	public Collection<MessageId> getMessagesToShare(Transaction transaction)
+			throws DbException {
 		T txn = unbox(transaction);
-		return db.getMessagesToShare(txn, c);
+		return db.getMessagesToShare(txn);
 	}
 
 	@Nullable
@@ -583,6 +571,13 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 		return db.getMessageDependents(txn, m);
 	}
 
+	@Override
+	public long getNextSendTime(Transaction transaction, ContactId c)
+			throws DbException {
+		T txn = unbox(transaction);
+		return db.getNextSendTime(txn, c);
+	}
+
 	@Override
 	public Settings getSettings(Transaction transaction, String namespace)
 			throws DbException {
@@ -677,7 +672,7 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 				db.raiseSeenFlag(txn, c, m.getId());
 				db.raiseAckFlag(txn, c, m.getId());
 			} else {
-				addMessage(txn, m, UNKNOWN, false, c);
+				db.addMessage(txn, m, UNKNOWN, false, c);
 				transaction.attach(new MessageAddedEvent(m, c));
 			}
 			transaction.attach(new MessageToAckEvent(c));
@@ -745,7 +740,8 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 		GroupId id = g.getId();
 		if (!db.containsGroup(txn, id))
 			throw new NoSuchGroupException();
-		Collection<ContactId> affected = db.getGroupVisibility(txn, id);
+		Collection<ContactId> affected =
+				db.getGroupVisibility(txn, id).keySet();
 		db.removeGroup(txn, id);
 		transaction.attach(new GroupRemovedEvent(g));
 		transaction.attach(new GroupVisibilityUpdatedEvent(affected));
@@ -815,19 +811,9 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 			throw new NoSuchGroupException();
 		Visibility old = db.getGroupVisibility(txn, c, g);
 		if (old == v) return;
-		if (old == INVISIBLE) {
-			db.addGroupVisibility(txn, c, g, v == SHARED);
-			for (MessageId m : db.getMessageIds(txn, g)) {
-				boolean seen = db.removeOfferedMessage(txn, c, m);
-				db.addStatus(txn, c, m, seen, seen);
-			}
-		} else if (v == INVISIBLE) {
-			db.removeGroupVisibility(txn, c, g);
-			for (MessageId m : db.getMessageIds(txn, g))
-				db.removeStatus(txn, c, m);
-		} else {
-			db.setGroupVisibility(txn, c, g, v == SHARED);
-		}
+		if (old == INVISIBLE) db.addGroupVisibility(txn, c, g, v == SHARED);
+		else if (v == INVISIBLE) db.removeGroupVisibility(txn, c, g);
+		else db.setGroupVisibility(txn, c, g, v == SHARED);
 		List<ContactId> affected = Collections.singletonList(c);
 		transaction.attach(new GroupVisibilityUpdatedEvent(affected));
 	}

bramble-core/src/main/java/org/briarproject/bramble/db/DatabaseConstants.java

@@ -23,10 +23,4 @@ interface DatabaseConstants {
 	 */
 	String SCHEMA_VERSION_KEY = "schemaVersion";
 
-	/**
-	 * The {@link Settings} key under which the minimum supported database
-	 * schema version is stored.
-	 */
-	String MIN_SCHEMA_VERSION_KEY = "minSchemaVersion";
-
 }

bramble-core/src/main/java/org/briarproject/bramble/db/H2Database.java

@@ -3,6 +3,7 @@ package org.briarproject.bramble.db;
 import org.briarproject.bramble.api.crypto.SecretKey;
 import org.briarproject.bramble.api.db.DatabaseConfig;
 import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.db.MigrationListener;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.system.Clock;
 import org.briarproject.bramble.util.StringUtils;
@@ -13,6 +14,7 @@ import java.sql.DriverManager;
 import java.sql.SQLException;
 import java.util.Properties;
 
+import javax.annotation.Nullable;
 import javax.inject.Inject;
 
 /**
@@ -40,10 +42,11 @@ class H2Database extends JdbcDatabase {
 	}
 
 	@Override
-	public boolean open() throws DbException {
+	public boolean open(@Nullable MigrationListener listener)
+			throws DbException {
 		boolean reopen = config.databaseExists();
 		if (!reopen) config.getDatabaseDirectory().mkdirs();
-		super.open("org.h2.Driver", reopen);
+		super.open("org.h2.Driver", reopen, listener);
 		return reopen;
 	}
 

bramble-core/src/main/java/org/briarproject/bramble/db/JdbcDatabase.java

@@ -3,9 +3,12 @@ package org.briarproject.bramble.db;
 import org.briarproject.bramble.api.contact.Contact;
 import org.briarproject.bramble.api.contact.ContactId;
 import org.briarproject.bramble.api.crypto.SecretKey;
+import org.briarproject.bramble.api.db.DataTooNewException;
+import org.briarproject.bramble.api.db.DataTooOldException;
 import org.briarproject.bramble.api.db.DbClosedException;
 import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.db.Metadata;
+import org.briarproject.bramble.api.db.MigrationListener;
 import org.briarproject.bramble.api.identity.Author;
 import org.briarproject.bramble.api.identity.AuthorId;
 import org.briarproject.bramble.api.identity.LocalAuthor;
@@ -31,6 +34,7 @@ import java.sql.ResultSet;
 import java.sql.SQLException;
 import java.sql.Statement;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.HashMap;
@@ -47,6 +51,7 @@ import java.util.logging.Logger;
 
 import javax.annotation.Nullable;
 
+import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
 import static org.briarproject.bramble.api.db.Metadata.REMOVE;
 import static org.briarproject.bramble.api.sync.Group.Visibility.INVISIBLE;
@@ -57,7 +62,6 @@ import static org.briarproject.bramble.api.sync.ValidationManager.State.INVALID;
 import static org.briarproject.bramble.api.sync.ValidationManager.State.PENDING;
 import static org.briarproject.bramble.api.sync.ValidationManager.State.UNKNOWN;
 import static org.briarproject.bramble.db.DatabaseConstants.DB_SETTINGS_NAMESPACE;
-import static org.briarproject.bramble.db.DatabaseConstants.MIN_SCHEMA_VERSION_KEY;
 import static org.briarproject.bramble.db.DatabaseConstants.SCHEMA_VERSION_KEY;
 import static org.briarproject.bramble.db.ExponentialBackoff.calculateExpiry;
 
@@ -68,8 +72,8 @@ import static org.briarproject.bramble.db.ExponentialBackoff.calculateExpiry;
 @NotNullByDefault
 abstract class JdbcDatabase implements Database<Connection> {
 
-	private static final int SCHEMA_VERSION = 30;
-	private static final int MIN_SCHEMA_VERSION = 30;
+	// Package access for testing
+	static final int CODE_SCHEMA_VERSION = 32;
 
 	private static final String CREATE_SETTINGS =
 			"CREATE TABLE settings"
@@ -148,11 +152,16 @@ abstract class JdbcDatabase implements Database<Connection> {
 	private static final String CREATE_MESSAGE_METADATA =
 			"CREATE TABLE messageMetadata"
 					+ " (messageId HASH NOT NULL,"
+					+ " groupId HASH NOT NULL," // Denormalised
+					+ " state INT NOT NULL," // Denormalised
 					+ " key VARCHAR NOT NULL,"
 					+ " value BINARY NOT NULL,"
 					+ " PRIMARY KEY (messageId, key),"
 					+ " FOREIGN KEY (messageId)"
 					+ " REFERENCES messages (messageId)"
+					+ " ON DELETE CASCADE,"
+					+ " FOREIGN KEY (groupId)"
+					+ " REFERENCES groups (groupId)"
 					+ " ON DELETE CASCADE)";
 
 	private static final String CREATE_MESSAGE_DEPENDENCIES =
@@ -180,6 +189,13 @@ abstract class JdbcDatabase implements Database<Connection> {
 			"CREATE TABLE statuses"
 					+ " (messageId HASH NOT NULL,"
 					+ " contactId INT NOT NULL,"
+					+ " groupId HASH NOT NULL," // Denormalised
+					+ " timestamp BIGINT NOT NULL," // Denormalised
+					+ " length INT NOT NULL," // Denormalised
+					+ " state INT NOT NULL," // Denormalised
+					+ " groupShared BOOLEAN NOT NULL," // Denormalised
+					+ " messageShared BOOLEAN NOT NULL," // Denormalised
+					+ " deleted BOOLEAN NOT NULL," // Denormalised
 					+ " ack BOOLEAN NOT NULL,"
 					+ " seen BOOLEAN NOT NULL,"
 					+ " requested BOOLEAN NOT NULL,"
@@ -191,6 +207,9 @@ abstract class JdbcDatabase implements Database<Connection> {
 					+ " ON DELETE CASCADE,"
 					+ " FOREIGN KEY (contactId)"
 					+ " REFERENCES contacts (contactId)"
+					+ " ON DELETE CASCADE,"
+					+ " FOREIGN KEY (groupId)"
+					+ " REFERENCES groups (groupId)"
 					+ " ON DELETE CASCADE)";
 
 	private static final String CREATE_TRANSPORTS =
@@ -236,25 +255,21 @@ abstract class JdbcDatabase implements Database<Connection> {
 			"CREATE INDEX IF NOT EXISTS contactsByAuthorId"
 					+ " ON contacts (authorId)";
 
-	private static final String INDEX_MESSAGES_BY_GROUP_ID =
-			"CREATE INDEX IF NOT EXISTS messagesByGroupId"
-					+ " ON messages (groupId)";
-
-	private static final String INDEX_OFFERS_BY_CONTACT_ID =
-			"CREATE INDEX IF NOT EXISTS offersByContactId"
-					+ " ON offers (contactId)";
-
 	private static final String INDEX_GROUPS_BY_CLIENT_ID =
 			"CREATE INDEX IF NOT EXISTS groupsByClientId"
 					+ " ON groups (clientId)";
 
-	private static final String INDEX_MESSAGE_METADATA_BY_MESSAGE_ID =
-			"CREATE INDEX IF NOT EXISTS messageMetadataByMessageId"
-					+ " ON messageMetadata (messageId)";
+	private static final String INDEX_MESSAGE_METADATA_BY_GROUP_ID_STATE =
+			"CREATE INDEX IF NOT EXISTS messageMetadataByGroupIdState"
+					+ " ON messageMetadata (groupId, state)";
 
-	private static final String INDEX_GROUP_METADATA_BY_GROUP_ID =
-			"CREATE INDEX IF NOT EXISTS groupMetadataByGroupId"
-					+ " ON groupMetadata (groupId)";
+	private static final String INDEX_STATUSES_BY_CONTACT_ID_GROUP_ID =
+			"CREATE INDEX IF NOT EXISTS statusesByContactIdGroupId"
+					+ " ON statuses (contactId, groupId)";
+
+	private static final String INDEX_STATUSES_BY_CONTACT_ID_TIMESTAMP =
+			"CREATE INDEX IF NOT EXISTS statusesByContactIdTimestamp"
+					+ " ON statuses (contactId, timestamp)";
 
 	private static final Logger LOG =
 			Logger.getLogger(JdbcDatabase.class.getName());
@@ -284,7 +299,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 		this.clock = clock;
 	}
 
-	protected void open(String driverClass, boolean reopen) throws DbException {
+	protected void open(String driverClass, boolean reopen,
+			@Nullable MigrationListener listener) throws DbException {
 		// Load the JDBC driver
 		try {
 			Class.forName(driverClass);
@@ -295,10 +311,10 @@ abstract class JdbcDatabase implements Database<Connection> {
 		Connection txn = startTransaction();
 		try {
 			if (reopen) {
-				if (!checkSchemaVersion(txn)) throw new DbException();
+				checkSchemaVersion(txn, listener);
 			} else {
 				createTables(txn);
-				storeSchemaVersion(txn);
+				storeSchemaVersion(txn, CODE_SCHEMA_VERSION);
 			}
 			createIndexes(txn);
 			commitTransaction(txn);
@@ -308,19 +324,51 @@ abstract class JdbcDatabase implements Database<Connection> {
 		}
 	}
 
-	private boolean checkSchemaVersion(Connection txn) throws DbException {
+	/**
+	 * Compares the schema version stored in the database with the schema
+	 * version used by the current code and applies any suitable migrations to
+	 * the data if necessary.
+	 *
+	 * @throws DataTooNewException if the data uses a newer schema than the
+	 * current code
+	 * @throws DataTooOldException if the data uses an older schema than the
+	 * current code and cannot be migrated
+	 */
+	private void checkSchemaVersion(Connection txn,
+			@Nullable MigrationListener listener) throws DbException {
 		Settings s = getSettings(txn, DB_SETTINGS_NAMESPACE);
-		int schemaVersion = s.getInt(SCHEMA_VERSION_KEY, -1);
-		if (schemaVersion == SCHEMA_VERSION) return true;
-		if (schemaVersion < MIN_SCHEMA_VERSION) return false;
-		int minSchemaVersion = s.getInt(MIN_SCHEMA_VERSION_KEY, -1);
-		return SCHEMA_VERSION >= minSchemaVersion;
+		int dataSchemaVersion = s.getInt(SCHEMA_VERSION_KEY, -1);
+		if (dataSchemaVersion == -1) throw new DbException();
+		if (dataSchemaVersion == CODE_SCHEMA_VERSION) return;
+		if (CODE_SCHEMA_VERSION < dataSchemaVersion)
+			throw new DataTooNewException();
+		// Apply any suitable migrations in order
+		for (Migration<Connection> m : getMigrations()) {
+			int start = m.getStartVersion(), end = m.getEndVersion();
+			if (start == dataSchemaVersion) {
+				if (LOG.isLoggable(INFO))
+					LOG.info("Migrating from schema " + start + " to " + end);
+				if (listener != null) listener.onMigrationRun();
+				// Apply the migration
+				m.migrate(txn);
+				// Store the new schema version
+				storeSchemaVersion(txn, end);
+				dataSchemaVersion = end;
+			}
+		}
+		if (dataSchemaVersion != CODE_SCHEMA_VERSION)
+			throw new DataTooOldException();
 	}
 
-	private void storeSchemaVersion(Connection txn) throws DbException {
+	// Package access for testing
+	List<Migration<Connection>> getMigrations() {
+		return Arrays.asList(new Migration30_31(), new Migration31_32());
+	}
+
+	private void storeSchemaVersion(Connection txn, int version)
+			throws DbException {
 		Settings s = new Settings();
-		s.putInt(SCHEMA_VERSION_KEY, SCHEMA_VERSION);
-		s.putInt(MIN_SCHEMA_VERSION_KEY, MIN_SCHEMA_VERSION);
+		s.putInt(SCHEMA_VERSION_KEY, version);
 		mergeSettings(txn, s, DB_SETTINGS_NAMESPACE);
 	}
 
@@ -370,11 +418,10 @@ abstract class JdbcDatabase implements Database<Connection> {
 		try {
 			s = txn.createStatement();
 			s.executeUpdate(INDEX_CONTACTS_BY_AUTHOR_ID);
-			s.executeUpdate(INDEX_MESSAGES_BY_GROUP_ID);
-			s.executeUpdate(INDEX_OFFERS_BY_CONTACT_ID);
 			s.executeUpdate(INDEX_GROUPS_BY_CLIENT_ID);
-			s.executeUpdate(INDEX_MESSAGE_METADATA_BY_MESSAGE_ID);
-			s.executeUpdate(INDEX_GROUP_METADATA_BY_GROUP_ID);
+			s.executeUpdate(INDEX_MESSAGE_METADATA_BY_GROUP_ID_STATE);
+			s.executeUpdate(INDEX_STATUSES_BY_CONTACT_ID_GROUP_ID);
+			s.executeUpdate(INDEX_STATUSES_BY_CONTACT_ID_TIMESTAMP);
 			s.close();
 		} catch (SQLException e) {
 			tryToClose(s);
@@ -500,7 +547,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 		try {
 			// Create a contact row
 			String sql = "INSERT INTO contacts"
-					+ " (authorId, name, publicKey, localAuthorId, verified, active)"
+					+ " (authorId, name, publicKey, localAuthorId,"
+					+ " verified, active)"
 					+ " VALUES (?, ?, ?, ?, ?, ?)";
 			ps = txn.prepareStatement(sql);
 			ps.setBytes(1, remote.getId().getBytes());
@@ -551,7 +599,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 
 	@Override
 	public void addGroupVisibility(Connection txn, ContactId c, GroupId g,
-			boolean shared) throws DbException {
+			boolean groupShared) throws DbException {
 		PreparedStatement ps = null;
 		try {
 			String sql = "INSERT INTO groupVisibilities"
@@ -560,16 +608,50 @@ abstract class JdbcDatabase implements Database<Connection> {
 			ps = txn.prepareStatement(sql);
 			ps.setInt(1, c.getInt());
 			ps.setBytes(2, g.getBytes());
-			ps.setBoolean(3, shared);
+			ps.setBoolean(3, groupShared);
 			int affected = ps.executeUpdate();
 			if (affected != 1) throw new DbStateException();
 			ps.close();
+			// Create a status row for each message in the group
+			addStatus(txn, c, g, groupShared);
 		} catch (SQLException e) {
 			tryToClose(ps);
 			throw new DbException(e);
 		}
 	}
 
+	private void addStatus(Connection txn, ContactId c, GroupId g,
+			boolean groupShared) throws DbException {
+		PreparedStatement ps = null;
+		ResultSet rs = null;
+		try {
+			String sql = "SELECT messageId, timestamp, state, shared,"
+					+ " length, raw IS NULL"
+					+ " FROM messages"
+					+ " WHERE groupId = ?";
+			ps = txn.prepareStatement(sql);
+			ps.setBytes(1, g.getBytes());
+			rs = ps.executeQuery();
+			while (rs.next()) {
+				MessageId id = new MessageId(rs.getBytes(1));
+				long timestamp = rs.getLong(2);
+				State state = State.fromValue(rs.getInt(3));
+				boolean messageShared = rs.getBoolean(4);
+				int length = rs.getInt(5);
+				boolean deleted = rs.getBoolean(6);
+				boolean seen = removeOfferedMessage(txn, c, id);
+				addStatus(txn, id, c, g, timestamp, length, state, groupShared,
+						messageShared, deleted, seen);
+			}
+			rs.close();
+			ps.close();
+		} catch (SQLException e) {
+			tryToClose(rs);
+			tryToClose(ps);
+			throw new DbException(e);
+		}
+	}
+
 	@Override
 	public void addLocalAuthor(Connection txn, LocalAuthor a)
 			throws DbException {
@@ -595,7 +677,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 
 	@Override
 	public void addMessage(Connection txn, Message m, State state,
-			boolean shared) throws DbException {
+			boolean messageShared, @Nullable ContactId sender)
+			throws DbException {
 		PreparedStatement ps = null;
 		try {
 			String sql = "INSERT INTO messages (messageId, groupId, timestamp,"
@@ -606,13 +689,24 @@ abstract class JdbcDatabase implements Database<Connection> {
 			ps.setBytes(2, m.getGroupId().getBytes());
 			ps.setLong(3, m.getTimestamp());
 			ps.setInt(4, state.getValue());
-			ps.setBoolean(5, shared);
+			ps.setBoolean(5, messageShared);
 			byte[] raw = m.getRaw();
 			ps.setInt(6, raw.length);
 			ps.setBytes(7, raw);
 			int affected = ps.executeUpdate();
 			if (affected != 1) throw new DbStateException();
 			ps.close();
+			// Create a status row for each contact that can see the group
+			Map<ContactId, Boolean> visibility =
+					getGroupVisibility(txn, m.getGroupId());
+			for (Entry<ContactId, Boolean> e : visibility.entrySet()) {
+				ContactId c = e.getKey();
+				boolean offered = removeOfferedMessage(txn, c, m.getId());
+				boolean seen = offered || (sender != null && c.equals(sender));
+				addStatus(txn, m.getId(), c, m.getGroupId(), m.getTimestamp(),
+						m.getLength(), state, e.getValue(), messageShared,
+						false, seen);
+			}
 		} catch (SQLException e) {
 			tryToClose(ps);
 			throw new DbException(e);
@@ -650,19 +744,28 @@ abstract class JdbcDatabase implements Database<Connection> {
 		}
 	}
 
-	@Override
-	public void addStatus(Connection txn, ContactId c, MessageId m, boolean ack,
-			boolean seen) throws DbException {
+	private void addStatus(Connection txn, MessageId m, ContactId c, GroupId g,
+			long timestamp, int length, State state, boolean groupShared,
+			boolean messageShared, boolean deleted, boolean seen)
+			throws DbException {
 		PreparedStatement ps = null;
 		try {
-			String sql = "INSERT INTO statuses (messageId, contactId, ack,"
-					+ " seen, requested, expiry, txCount)"
-					+ " VALUES (?, ?, ?, ?, FALSE, 0, 0)";
+			String sql = "INSERT INTO statuses (messageId, contactId, groupId,"
+					+ " timestamp, length, state, groupShared, messageShared,"
+					+ " deleted, ack, seen, requested, expiry, txCount)"
+					+ " VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, FALSE, 0, 0)";
 			ps = txn.prepareStatement(sql);
 			ps.setBytes(1, m.getBytes());
 			ps.setInt(2, c.getInt());
-			ps.setBoolean(3, ack);
-			ps.setBoolean(4, seen);
+			ps.setBytes(3, g.getBytes());
+			ps.setLong(4, timestamp);
+			ps.setInt(5, length);
+			ps.setInt(6, state.getValue());
+			ps.setBoolean(7, groupShared);
+			ps.setBoolean(8, messageShared);
+			ps.setBoolean(9, deleted);
+			ps.setBoolean(10, seen);
+			ps.setBoolean(11, seen);
 			int affected = ps.executeUpdate();
 			if (affected != 1) throw new DbStateException();
 			ps.close();
@@ -914,12 +1017,9 @@ abstract class JdbcDatabase implements Database<Connection> {
 		PreparedStatement ps = null;
 		ResultSet rs = null;
 		try {
-			String sql = "SELECT NULL FROM messages AS m"
-					+ " JOIN groupVisibilities AS gv"
-					+ " ON m.groupId = gv.groupId"
-					+ " WHERE messageId = ?"
-					+ " AND contactId = ?"
-					+ " AND m.shared = TRUE";
+			String sql = "SELECT NULL FROM statuses"
+					+ " WHERE messageId = ? AND contactId = ?"
+					+ " AND messageShared = TRUE";
 			ps = txn.prepareStatement(sql);
 			ps.setBytes(1, m.getBytes());
 			ps.setInt(2, c.getInt());
@@ -971,6 +1071,13 @@ abstract class JdbcDatabase implements Database<Connection> {
 			if (affected < 0) throw new DbStateException();
 			if (affected > 1) throw new DbStateException();
 			ps.close();
+			// Update denormalised column in statuses
+			sql = "UPDATE statuses SET deleted = TRUE WHERE messageId = ?";
+			ps = txn.prepareStatement(sql);
+			ps.setBytes(1, m.getBytes());
+			affected = ps.executeUpdate();
+			if (affected < 0) throw new DbStateException();
+			ps.close();
 		} catch (SQLException e) {
 			tryToClose(ps);
 			throw new DbException(e);
@@ -1193,18 +1300,19 @@ abstract class JdbcDatabase implements Database<Connection> {
 	}
 
 	@Override
-	public Collection<ContactId> getGroupVisibility(Connection txn, GroupId g)
+	public Map<ContactId, Boolean> getGroupVisibility(Connection txn, GroupId g)
 			throws DbException {
 		PreparedStatement ps = null;
 		ResultSet rs = null;
 		try {
-			String sql = "SELECT contactId FROM groupVisibilities"
+			String sql = "SELECT contactId, shared FROM groupVisibilities"
 					+ " WHERE groupId = ?";
 			ps = txn.prepareStatement(sql);
 			ps.setBytes(1, g.getBytes());
 			rs = ps.executeQuery();
-			List<ContactId> visible = new ArrayList<>();
-			while (rs.next()) visible.add(new ContactId(rs.getInt(1)));
+			Map<ContactId, Boolean> visible = new HashMap<>();
+			while (rs.next())
+				visible.put(new ContactId(rs.getInt(1)), rs.getBoolean(2));
 			rs.close();
 			ps.close();
 			return visible;
@@ -1330,16 +1438,13 @@ abstract class JdbcDatabase implements Database<Connection> {
 		try {
 			// Retrieve the message IDs for each query term and intersect
 			Set<MessageId> intersection = null;
-			String sql = "SELECT m.messageId"
-					+ " FROM messages AS m"
-					+ " JOIN messageMetadata AS md"
-					+ " ON m.messageId = md.messageId"
-					+ " WHERE state = ? AND groupId = ?"
+			String sql = "SELECT messageId FROM messageMetadata"
+					+ " WHERE groupId = ? AND state = ?"
 					+ " AND key = ? AND value = ?";
 			for (Entry<String, byte[]> e : query.entrySet()) {
 				ps = txn.prepareStatement(sql);
-				ps.setInt(1, DELIVERED.getValue());
-				ps.setBytes(2, g.getBytes());
+				ps.setBytes(1, g.getBytes());
+				ps.setInt(2, DELIVERED.getValue());
 				ps.setString(3, e.getKey());
 				ps.setBytes(4, e.getValue());
 				rs = ps.executeQuery();
@@ -1367,25 +1472,20 @@ abstract class JdbcDatabase implements Database<Connection> {
 		PreparedStatement ps = null;
 		ResultSet rs = null;
 		try {
-			String sql = "SELECT m.messageId, key, value"
-					+ " FROM messages AS m"
-					+ " JOIN messageMetadata AS md"
-					+ " ON m.messageId = md.messageId"
-					+ " WHERE state = ? AND groupId = ?"
-					+ " ORDER BY m.messageId";
+			String sql = "SELECT messageId, key, value"
+					+ " FROM messageMetadata"
+					+ " WHERE groupId = ? AND state = ?";
 			ps = txn.prepareStatement(sql);
-			ps.setInt(1, DELIVERED.getValue());
-			ps.setBytes(2, g.getBytes());
+			ps.setBytes(1, g.getBytes());
+			ps.setInt(2, DELIVERED.getValue());
 			rs = ps.executeQuery();
 			Map<MessageId, Metadata> all = new HashMap<>();
-			Metadata metadata = null;
-			MessageId lastMessageId = null;
 			while (rs.next()) {
 				MessageId messageId = new MessageId(rs.getBytes(1));
-				if (lastMessageId == null || !messageId.equals(lastMessageId)) {
+				Metadata metadata = all.get(messageId);
+				if (metadata == null) {
 					metadata = new Metadata();
 					all.put(messageId, metadata);
-					lastMessageId = messageId;
 				}
 				metadata.put(rs.getString(2), rs.getBytes(3));
 			}
@@ -1440,10 +1540,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 		PreparedStatement ps = null;
 		ResultSet rs = null;
 		try {
-			String sql = "SELECT key, value FROM messageMetadata AS md"
-					+ " JOIN messages AS m"
-					+ " ON m.messageId = md.messageId"
-					+ " WHERE m.state = ? AND md.messageId = ?";
+			String sql = "SELECT key, value FROM messageMetadata"
+					+ " WHERE state = ? AND messageId = ?";
 			ps = txn.prepareStatement(sql);
 			ps.setInt(1, DELIVERED.getValue());
 			ps.setBytes(2, m.getBytes());
@@ -1466,11 +1564,9 @@ abstract class JdbcDatabase implements Database<Connection> {
 		PreparedStatement ps = null;
 		ResultSet rs = null;
 		try {
-			String sql = "SELECT key, value FROM messageMetadata AS md"
-					+ " JOIN messages AS m"
-					+ " ON m.messageId = md.messageId"
-					+ " WHERE (m.state = ? OR m.state = ?)"
-					+ " AND md.messageId = ?";
+			String sql = "SELECT key, value FROM messageMetadata"
+					+ " WHERE (state = ? OR state = ?)"
+					+ " AND messageId = ?";
 			ps = txn.prepareStatement(sql);
 			ps.setInt(1, DELIVERED.getValue());
 			ps.setInt(2, PENDING.getValue());
@@ -1494,12 +1590,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 		PreparedStatement ps = null;
 		ResultSet rs = null;
 		try {
-			String sql = "SELECT m.messageId, txCount > 0, seen"
-					+ " FROM messages AS m"
-					+ " JOIN statuses AS s"
-					+ " ON m.messageId = s.messageId"
-					+ " WHERE groupId = ?"
-					+ " AND contactId = ?";
+			String sql = "SELECT messageId, txCount > 0, seen FROM statuses"
+					+ " WHERE groupId = ? AND contactId = ?";
 			ps = txn.prepareStatement(sql);
 			ps.setBytes(1, g.getBytes());
 			ps.setInt(2, c.getInt());
@@ -1522,15 +1614,13 @@ abstract class JdbcDatabase implements Database<Connection> {
 	}
 
 	@Override
-	public MessageStatus getMessageStatus(Connection txn,
-			ContactId c, MessageId m) throws DbException {
+	public MessageStatus getMessageStatus(Connection txn, ContactId c,
+			MessageId m) throws DbException {
 		PreparedStatement ps = null;
 		ResultSet rs = null;
 		try {
-			String sql = "SELECT txCount > 0, seen"
-					+ " FROM statuses"
-					+ " WHERE messageId = ?"
-					+ " AND contactId = ?";
+			String sql = "SELECT txCount > 0, seen FROM statuses"
+					+ " WHERE messageId = ? AND contactId = ?";
 			ps = txn.prepareStatement(sql);
 			ps.setBytes(1, m.getBytes());
 			ps.setInt(2, c.getInt());
@@ -1672,14 +1762,10 @@ abstract class JdbcDatabase implements Database<Connection> {
 		PreparedStatement ps = null;
 		ResultSet rs = null;
 		try {
-			String sql = "SELECT m.messageId FROM messages AS m"
-					+ " JOIN groupVisibilities AS gv"
-					+ " ON m.groupId = gv.groupId"
-					+ " JOIN statuses AS s"
-					+ " ON m.messageId = s.messageId"
-					+ " AND gv.contactId = s.contactId"
-					+ " WHERE gv.contactId = ? AND gv.shared = TRUE"
-					+ " AND state = ? AND m.shared = TRUE AND raw IS NOT NULL"
+			String sql = "SELECT messageId FROM statuses"
+					+ " WHERE contactId = ? AND state = ?"
+					+ " AND groupShared = TRUE AND messageShared = TRUE"
+					+ " AND deleted = FALSE"
 					+ " AND seen = FALSE AND requested = FALSE"
 					+ " AND expiry < ?"
 					+ " ORDER BY timestamp LIMIT ?";
@@ -1733,14 +1819,10 @@ abstract class JdbcDatabase implements Database<Connection> {
 		PreparedStatement ps = null;
 		ResultSet rs = null;
 		try {
-			String sql = "SELECT length, m.messageId FROM messages AS m"
-					+ " JOIN groupVisibilities AS gv"
-					+ " ON m.groupId = gv.groupId"
-					+ " JOIN statuses AS s"
-					+ " ON m.messageId = s.messageId"
-					+ " AND gv.contactId = s.contactId"
-					+ " WHERE gv.contactId = ? AND gv.shared = TRUE"
-					+ " AND state = ? AND m.shared = TRUE AND raw IS NOT NULL"
+			String sql = "SELECT length, messageId FROM statuses"
+					+ " WHERE contactId = ? AND state = ?"
+					+ " AND groupShared = TRUE AND messageShared = TRUE"
+					+ " AND deleted = FALSE"
 					+ " AND seen = FALSE"
 					+ " AND expiry < ?"
 					+ " ORDER BY timestamp";
@@ -1768,28 +1850,26 @@ abstract class JdbcDatabase implements Database<Connection> {
 	}
 
 	@Override
-	public Collection<MessageId> getMessagesToValidate(Connection txn,
-			ClientId c) throws DbException {
-		return getMessagesInState(txn, c, UNKNOWN);
+	public Collection<MessageId> getMessagesToValidate(Connection txn)
+			throws DbException {
+		return getMessagesInState(txn, UNKNOWN);
 	}
 
 	@Override
-	public Collection<MessageId> getPendingMessages(Connection txn,
-			ClientId c) throws DbException {
-		return getMessagesInState(txn, c, PENDING);
+	public Collection<MessageId> getPendingMessages(Connection txn)
+			throws DbException {
+		return getMessagesInState(txn, PENDING);
 	}
 
-	private Collection<MessageId> getMessagesInState(Connection txn, ClientId c,
+	private Collection<MessageId> getMessagesInState(Connection txn,
 			State state) throws DbException {
 		PreparedStatement ps = null;
 		ResultSet rs = null;
 		try {
-			String sql = "SELECT messageId FROM messages AS m"
-					+ " JOIN groups AS g ON m.groupId = g.groupId"
-					+ " WHERE state = ? AND clientId = ? AND raw IS NOT NULL";
+			String sql = "SELECT messageId FROM messages"
+					+ " WHERE state = ? AND raw IS NOT NULL";
 			ps = txn.prepareStatement(sql);
 			ps.setInt(1, state.getValue());
-			ps.setString(2, c.getString());
 			rs = ps.executeQuery();
 			List<MessageId> ids = new ArrayList<>();
 			while (rs.next()) ids.add(new MessageId(rs.getBytes(1)));
@@ -1804,8 +1884,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 	}
 
 	@Override
-	public Collection<MessageId> getMessagesToShare(
-			Connection txn, ClientId c) throws DbException {
+	public Collection<MessageId> getMessagesToShare(Connection txn)
+			throws DbException {
 		PreparedStatement ps = null;
 		ResultSet rs = null;
 		try {
@@ -1814,12 +1894,10 @@ abstract class JdbcDatabase implements Database<Connection> {
 					+ " ON m.messageId = d.dependencyId"
 					+ " JOIN messages AS m1"
 					+ " ON d.messageId = m1.messageId"
-					+ " JOIN groups AS g"
-					+ " ON m.groupId = g.groupId"
-					+ " WHERE m.shared = FALSE AND m1.shared = TRUE"
-					+ " AND g.clientId = ?";
+					+ " WHERE m.state = ?"
+					+ " AND m.shared = FALSE AND m1.shared = TRUE";
 			ps = txn.prepareStatement(sql);
-			ps.setString(1, c.getString());
+			ps.setInt(1, DELIVERED.getValue());
 			rs = ps.executeQuery();
 			List<MessageId> ids = new ArrayList<>();
 			while (rs.next()) ids.add(new MessageId(rs.getBytes(1)));
@@ -1833,6 +1911,36 @@ abstract class JdbcDatabase implements Database<Connection> {
 		}
 	}
 
+	@Override
+	public long getNextSendTime(Connection txn, ContactId c)
+			throws DbException {
+		PreparedStatement ps = null;
+		ResultSet rs = null;
+		try {
+			String sql = "SELECT expiry FROM statuses"
+					+ " WHERE contactId = ? AND state = ?"
+					+ " AND groupShared = TRUE AND messageShared = TRUE"
+					+ " AND deleted = FALSE AND seen = FALSE"
+					+ " ORDER BY expiry LIMIT 1";
+			ps = txn.prepareStatement(sql);
+			ps.setInt(1, c.getInt());
+			ps.setInt(2, DELIVERED.getValue());
+			rs = ps.executeQuery();
+			long nextSendTime = Long.MAX_VALUE;
+			if (rs.next()) {
+				nextSendTime = rs.getLong(1);
+				if (rs.next()) throw new AssertionError();
+			}
+			rs.close();
+			ps.close();
+			return nextSendTime;
+		} catch (SQLException e) {
+			tryToClose(rs);
+			tryToClose(ps);
+			throw new DbException(e);
+		}
+	}
+
 	@Override
 	@Nullable
 	public byte[] getRawMessage(Connection txn, MessageId m)
@@ -1864,14 +1972,10 @@ abstract class JdbcDatabase implements Database<Connection> {
 		PreparedStatement ps = null;
 		ResultSet rs = null;
 		try {
-			String sql = "SELECT length, m.messageId FROM messages AS m"
-					+ " JOIN groupVisibilities AS gv"
-					+ " ON m.groupId = gv.groupId"
-					+ " JOIN statuses AS s"
-					+ " ON m.messageId = s.messageId"
-					+ " AND gv.contactId = s.contactId"
-					+ " WHERE gv.contactId = ? AND gv.shared = TRUE"
-					+ " AND state = ? AND m.shared = TRUE AND raw IS NOT NULL"
+			String sql = "SELECT length, messageId FROM statuses"
+					+ " WHERE contactId = ? AND state = ?"
+					+ " AND groupShared = TRUE AND messageShared = TRUE"
+					+ " AND deleted = FALSE"
 					+ " AND seen = FALSE AND requested = TRUE"
 					+ " AND expiry < ?"
 					+ " ORDER BY timestamp";
@@ -2044,7 +2148,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 			int[] batchAffected = ps.executeBatch();
 			if (batchAffected.length != requested.size())
 				throw new DbStateException();
-			for (int rows: batchAffected) {
+			for (int rows : batchAffected) {
 				if (rows < 0) throw new DbStateException();
 				if (rows > 1) throw new DbStateException();
 			}
@@ -2058,25 +2162,92 @@ abstract class JdbcDatabase implements Database<Connection> {
 	@Override
 	public void mergeGroupMetadata(Connection txn, GroupId g, Metadata meta)
 			throws DbException {
-		mergeMetadata(txn, g.getBytes(), meta, "groupMetadata", "groupId");
+		PreparedStatement ps = null;
+		try {
+			Map<String, byte[]> added = removeOrUpdateMetadata(txn,
+					g.getBytes(), meta, "groupMetadata", "groupId");
+			if (added.isEmpty()) return;
+			// Insert any keys that don't already exist
+			String sql = "INSERT INTO groupMetadata (groupId, key, value)"
+					+ " VALUES (?, ?, ?)";
+			ps = txn.prepareStatement(sql);
+			ps.setBytes(1, g.getBytes());
+			for (Entry<String, byte[]> e : added.entrySet()) {
+				ps.setString(2, e.getKey());
+				ps.setBytes(3, e.getValue());
+				ps.addBatch();
+			}
+			int[] batchAffected = ps.executeBatch();
+			if (batchAffected.length != added.size())
+				throw new DbStateException();
+			for (int rows : batchAffected)
+				if (rows != 1) throw new DbStateException();
+			ps.close();
+		} catch (SQLException e) {
+			tryToClose(ps);
+			throw new DbException(e);
+		}
 	}
 
 	@Override
-	public void mergeMessageMetadata(Connection txn, MessageId m, Metadata meta)
-			throws DbException {
-		mergeMetadata(txn, m.getBytes(), meta, "messageMetadata", "messageId");
+	public void mergeMessageMetadata(Connection txn, MessageId m,
+			Metadata meta) throws DbException {
+		PreparedStatement ps = null;
+		ResultSet rs = null;
+		try {
+			Map<String, byte[]> added = removeOrUpdateMetadata(txn,
+					m.getBytes(), meta, "messageMetadata", "messageId");
+			if (added.isEmpty()) return;
+			// Get the group ID and message state for the denormalised columns
+			String sql = "SELECT groupId, state FROM messages"
+					+ " WHERE messageId = ?";
+			ps = txn.prepareStatement(sql);
+			ps.setBytes(1, m.getBytes());
+			rs = ps.executeQuery();
+			if (!rs.next()) throw new DbStateException();
+			GroupId g = new GroupId(rs.getBytes(1));
+			State state = State.fromValue(rs.getInt(2));
+			rs.close();
+			ps.close();
+			// Insert any keys that don't already exist
+			sql = "INSERT INTO messageMetadata"
+					+ " (messageId, groupId, state, key, value)"
+					+ " VALUES (?, ?, ?, ?, ?)";
+			ps = txn.prepareStatement(sql);
+			ps.setBytes(1, m.getBytes());
+			ps.setBytes(2, g.getBytes());
+			ps.setInt(3, state.getValue());
+			for (Entry<String, byte[]> e : added.entrySet()) {
+				ps.setString(4, e.getKey());
+				ps.setBytes(5, e.getValue());
+				ps.addBatch();
+			}
+			int[] batchAffected = ps.executeBatch();
+			if (batchAffected.length != added.size())
+				throw new DbStateException();
+			for (int rows : batchAffected)
+				if (rows != 1) throw new DbStateException();
+			ps.close();
+		} catch (SQLException e) {
+			tryToClose(rs);
+			tryToClose(ps);
+			throw new DbException(e);
+		}
 	}
 
-	private void mergeMetadata(Connection txn, byte[] id, Metadata meta,
-			String tableName, String columnName) throws DbException {
+	// Removes or updates any existing entries, returns any entries that
+	// need to be added
+	private Map<String, byte[]> removeOrUpdateMetadata(Connection txn,
+			byte[] id, Metadata meta, String tableName, String columnName)
+			throws DbException {
 		PreparedStatement ps = null;
 		try {
 			// Determine which keys are being removed
 			List<String> removed = new ArrayList<>();
-			Map<String, byte[]> retained = new HashMap<>();
+			Map<String, byte[]> notRemoved = new HashMap<>();
 			for (Entry<String, byte[]> e : meta.entrySet()) {
 				if (e.getValue() == REMOVE) removed.add(e.getKey());
-				else retained.put(e.getKey(), e.getValue());
+				else notRemoved.put(e.getKey(), e.getValue());
 			}
 			// Delete any keys that are being removed
 			if (!removed.isEmpty()) {
@@ -2097,45 +2268,33 @@ abstract class JdbcDatabase implements Database<Connection> {
 				}
 				ps.close();
 			}
-			if (retained.isEmpty()) return;
+			if (notRemoved.isEmpty()) return Collections.emptyMap();
 			// Update any keys that already exist
 			String sql = "UPDATE " + tableName + " SET value = ?"
 					+ " WHERE " + columnName + " = ? AND key = ?";
 			ps = txn.prepareStatement(sql);
 			ps.setBytes(2, id);
-			for (Entry<String, byte[]> e : retained.entrySet()) {
+			for (Entry<String, byte[]> e : notRemoved.entrySet()) {
 				ps.setBytes(1, e.getValue());
 				ps.setString(3, e.getKey());
 				ps.addBatch();
 			}
 			int[] batchAffected = ps.executeBatch();
-			if (batchAffected.length != retained.size())
+			if (batchAffected.length != notRemoved.size())
 				throw new DbStateException();
 			for (int rows : batchAffected) {
 				if (rows < 0) throw new DbStateException();
 				if (rows > 1) throw new DbStateException();
 			}
-			// Insert any keys that don't already exist
-			sql = "INSERT INTO " + tableName
-					+ " (" + columnName + ", key, value)"
-					+ " VALUES (?, ?, ?)";
-			ps = txn.prepareStatement(sql);
-			ps.setBytes(1, id);
-			int updateIndex = 0, inserted = 0;
-			for (Entry<String, byte[]> e : retained.entrySet()) {
-				if (batchAffected[updateIndex] == 0) {
-					ps.setString(2, e.getKey());
-					ps.setBytes(3, e.getValue());
-					ps.addBatch();
-					inserted++;
-				}
-				updateIndex++;
-			}
-			batchAffected = ps.executeBatch();
-			if (batchAffected.length != inserted) throw new DbStateException();
-			for (int rows : batchAffected)
-				if (rows != 1) throw new DbStateException();
 			ps.close();
+			// Are there any keys that don't already exist?
+			Map<String, byte[]> added = new HashMap<>();
+			int updateIndex = 0;
+			for (Entry<String, byte[]> e : notRemoved.entrySet()) {
+				if (batchAffected[updateIndex++] == 0)
+					added.put(e.getKey(), e.getValue());
+			}
+			return added;
 		} catch (SQLException e) {
 			tryToClose(ps);
 			throw new DbException(e);
@@ -2292,6 +2451,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 			int affected = ps.executeUpdate();
 			if (affected != 1) throw new DbStateException();
 			ps.close();
+			// Remove status rows for the messages in the group
+			for (MessageId m : getMessageIds(txn, g)) removeStatus(txn, c, m);
 		} catch (SQLException e) {
 			tryToClose(ps);
 			throw new DbException(e);
@@ -2331,8 +2492,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 		}
 	}
 
-	@Override
-	public boolean removeOfferedMessage(Connection txn, ContactId c,
+	private boolean removeOfferedMessage(Connection txn, ContactId c,
 			MessageId m) throws DbException {
 		PreparedStatement ps = null;
 		try {
@@ -2376,16 +2536,15 @@ abstract class JdbcDatabase implements Database<Connection> {
 		}
 	}
 
-	@Override
-	public void removeStatus(Connection txn, ContactId c, MessageId m)
+	private void removeStatus(Connection txn, ContactId c, MessageId m)
 			throws DbException {
 		PreparedStatement ps = null;
 		try {
 			String sql = "DELETE FROM statuses"
-					+ " WHERE contactId = ? AND messageId = ?";
+					+ " WHERE messageId = ? AND contactId = ?";
 			ps = txn.prepareStatement(sql);
-			ps.setInt(1, c.getInt());
-			ps.setBytes(2, m.getBytes());
+			ps.setBytes(1, m.getBytes());
+			ps.setInt(2, c.getInt());
 			int affected = ps.executeUpdate();
 			if (affected != 1) throw new DbStateException();
 			ps.close();
@@ -2481,6 +2640,16 @@ abstract class JdbcDatabase implements Database<Connection> {
 			int affected = ps.executeUpdate();
 			if (affected < 0 || affected > 1) throw new DbStateException();
 			ps.close();
+			// Update denormalised column in statuses
+			sql = "UPDATE statuses SET groupShared = ?"
+					+ " WHERE contactId = ? AND groupId = ?";
+			ps = txn.prepareStatement(sql);
+			ps.setBoolean(1, shared);
+			ps.setInt(2, c.getInt());
+			ps.setBytes(3, g.getBytes());
+			affected = ps.executeUpdate();
+			if (affected < 0) throw new DbStateException();
+			ps.close();
 		} catch (SQLException e) {
 			tryToClose(ps);
 			throw new DbException(e);
@@ -2488,7 +2657,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 	}
 
 	@Override
-	public void setMessageShared(Connection txn, MessageId m) throws DbException {
+	public void setMessageShared(Connection txn, MessageId m)
+			throws DbException {
 		PreparedStatement ps = null;
 		try {
 			String sql = "UPDATE messages SET shared = TRUE"
@@ -2498,6 +2668,14 @@ abstract class JdbcDatabase implements Database<Connection> {
 			int affected = ps.executeUpdate();
 			if (affected < 0 || affected > 1) throw new DbStateException();
 			ps.close();
+			// Update denormalised column in statuses
+			sql = "UPDATE statuses SET messageShared = TRUE"
+					+ " WHERE messageId = ?";
+			ps = txn.prepareStatement(sql);
+			ps.setBytes(1, m.getBytes());
+			affected = ps.executeUpdate();
+			if (affected < 0) throw new DbStateException();
+			ps.close();
 		} catch (SQLException e) {
 			tryToClose(ps);
 			throw new DbException(e);
@@ -2516,6 +2694,22 @@ abstract class JdbcDatabase implements Database<Connection> {
 			int affected = ps.executeUpdate();
 			if (affected < 0 || affected > 1) throw new DbStateException();
 			ps.close();
+			// Update denormalised column in messageMetadata
+			sql = "UPDATE messageMetadata SET state = ? WHERE messageId = ?";
+			ps = txn.prepareStatement(sql);
+			ps.setInt(1, state.getValue());
+			ps.setBytes(2, m.getBytes());
+			affected = ps.executeUpdate();
+			if (affected < 0) throw new DbStateException();
+			ps.close();
+			// Update denormalised column in statuses
+			sql = "UPDATE statuses SET state = ? WHERE messageId = ?";
+			ps = txn.prepareStatement(sql);
+			ps.setInt(1, state.getValue());
+			ps.setBytes(2, m.getBytes());
+			affected = ps.executeUpdate();
+			if (affected < 0) throw new DbStateException();
+			ps.close();
 		} catch (SQLException e) {
 			tryToClose(ps);
 			throw new DbException(e);

bramble-core/src/main/java/org/briarproject/bramble/db/Migration.java

@@ -0,0 +1,18 @@
+package org.briarproject.bramble.db;
+
+import org.briarproject.bramble.api.db.DbException;
+
+interface Migration<T> {
+
+	/**
+	 * Returns the schema version from which this migration starts.
+	 */
+	int getStartVersion();
+
+	/**
+	 * Returns the schema version at which this migration ends.
+	 */
+	int getEndVersion();
+
+	void migrate(T txn) throws DbException;
+}

bramble-core/src/main/java/org/briarproject/bramble/db/Migration30_31.java

@@ -0,0 +1,75 @@
+package org.briarproject.bramble.db;
+
+import org.briarproject.bramble.api.db.DbException;
+
+import java.sql.Connection;
+import java.sql.SQLException;
+import java.sql.Statement;
+import java.util.logging.Logger;
+
+import javax.annotation.Nullable;
+
+import static java.util.logging.Level.WARNING;
+
+class Migration30_31 implements Migration<Connection> {
+
+	private static final Logger LOG =
+			Logger.getLogger(Migration30_31.class.getName());
+
+	@Override
+	public int getStartVersion() {
+		return 30;
+	}
+
+	@Override
+	public int getEndVersion() {
+		return 31;
+	}
+
+	@Override
+	public void migrate(Connection txn) throws DbException {
+		Statement s = null;
+		try {
+			s = txn.createStatement();
+			// Add groupId column
+			s.execute("ALTER TABLE messageMetadata"
+					+ " ADD COLUMN groupId BINARY(32) AFTER messageId");
+			// Populate groupId column
+			s.execute("UPDATE messageMetadata AS mm SET groupId ="
+					+ " (SELECT groupId FROM messages AS m"
+					+ " WHERE mm.messageId = m.messageId)");
+			// Add not null constraint now column has been populated
+			s.execute("ALTER TABLE messageMetadata"
+					+ " ALTER COLUMN groupId"
+					+ " SET NOT NULL");
+			// Add foreign key constraint
+			s.execute("ALTER TABLE messageMetadata"
+					+ " ADD CONSTRAINT groupIdForeignKey"
+					+ " FOREIGN KEY (groupId)"
+					+ " REFERENCES groups (groupId)"
+					+ " ON DELETE CASCADE");
+			// Add state column
+			s.execute("ALTER TABLE messageMetadata"
+					+ " ADD COLUMN state INT AFTER groupId");
+			// Populate state column
+			s.execute("UPDATE messageMetadata AS mm SET state ="
+					+ " (SELECT state FROM messages AS m"
+					+ " WHERE mm.messageId = m.messageId)");
+			// Add not null constraint now column has been populated
+			s.execute("ALTER TABLE messageMetadata"
+					+ " ALTER COLUMN state"
+					+ " SET NOT NULL");
+		} catch (SQLException e) {
+			tryToClose(s);
+			throw new DbException(e);
+		}
+	}
+
+	private void tryToClose(@Nullable Statement s) {
+		try {
+			if (s != null) s.close();
+		} catch (SQLException e) {
+			if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
+		}
+	}
+}

bramble-core/src/main/java/org/briarproject/bramble/db/Migration31_32.java

@@ -0,0 +1,84 @@
+package org.briarproject.bramble.db;
+
+import org.briarproject.bramble.api.db.DbException;
+
+import java.sql.Connection;
+import java.sql.SQLException;
+import java.sql.Statement;
+import java.util.logging.Logger;
+
+import javax.annotation.Nullable;
+
+import static java.util.logging.Level.WARNING;
+
+class Migration31_32 implements Migration<Connection> {
+
+	private static final Logger LOG =
+			Logger.getLogger(Migration31_32.class.getName());
+
+	@Override
+	public int getStartVersion() {
+		return 31;
+	}
+
+	@Override
+	public int getEndVersion() {
+		return 32;
+	}
+
+	@Override
+	public void migrate(Connection txn) throws DbException {
+		Statement s = null;
+		try {
+			s = txn.createStatement();
+			// Add denormalised columns
+			s.execute("ALTER TABLE statuses ADD COLUMN"
+					+ " (groupId BINARY(32),"
+					+ " timestamp BIGINT,"
+					+ " length INT,"
+					+ " state INT,"
+					+ " groupShared BOOLEAN,"
+					+ " messageShared BOOLEAN,"
+					+ " deleted BOOLEAN)");
+			// Populate columns from messages table
+			s.execute("UPDATE statuses AS s SET (groupId, timestamp, length,"
+					+ " state, messageShared, deleted) ="
+					+ " (SELECT groupId, timestamp, length, state, shared,"
+					+ " raw IS NULL FROM messages AS m"
+					+ " WHERE s.messageId = m.messageId)");
+			// Populate column from groupVisibilities table
+			s.execute("UPDATE statuses AS s SET groupShared ="
+					+ " (SELECT shared FROM groupVisibilities AS gv"
+					+ " WHERE s.contactId = gv.contactId"
+					+ " AND s.groupId = gv.groupId)");
+			// Add not null constraints now columns have been populated
+			s.execute("ALTER TABLE statuses ALTER COLUMN groupId SET NOT NULL");
+			s.execute("ALTER TABLE statuses ALTER COLUMN timestamp"
+					+ " SET NOT NULL");
+			s.execute("ALTER TABLE statuses ALTER COLUMN length SET NOT NULL");
+			s.execute("ALTER TABLE statuses ALTER COLUMN state SET NOT NULL");
+			s.execute("ALTER TABLE statuses ALTER COLUMN groupShared"
+					+ " SET NOT NULL");
+			s.execute("ALTER TABLE statuses ALTER COLUMN messageShared"
+					+ " SET NOT NULL");
+			s.execute("ALTER TABLE statuses ALTER COLUMN deleted SET NOT NULL");
+			// Add foreign key constraint
+			s.execute("ALTER TABLE statuses"
+					+ " ADD CONSTRAINT statusesForeignKeyGroupId"
+					+ " FOREIGN KEY (groupId)"
+					+ " REFERENCES groups (groupId)"
+					+ " ON DELETE CASCADE");
+		} catch (SQLException e) {
+			tryToClose(s);
+			throw new DbException(e);
+		}
+	}
+
+	private void tryToClose(@Nullable Statement s) {
+		try {
+			if (s != null) s.close();
+		} catch (SQLException e) {
+			if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
+		}
+	}
+}

bramble-core/src/main/java/org/briarproject/bramble/keyagreement/ConnectionChooser.java

@@ -0,0 +1,36 @@
+package org.briarproject.bramble.keyagreement;
+
+import org.briarproject.bramble.api.keyagreement.KeyAgreementConnection;
+
+import java.util.concurrent.Callable;
+
+import javax.annotation.Nullable;
+
+interface ConnectionChooser {
+
+	/**
+	 * Submits a connection task to the chooser.
+	 */
+	void submit(Callable<KeyAgreementConnection> task);
+
+	/**
+	 * Returns a connection returned by any of the tasks submitted to the
+	 * chooser, waiting up to the given amount of time for a connection if
+	 * necessary. Returns null if the time elapses without a connection
+	 * becoming available.
+	 *
+	 * @param timeout the timeout in milliseconds
+	 * @throws InterruptedException if the thread is interrupted while waiting
+	 * for a connection to become available
+	 */
+	@Nullable
+	KeyAgreementConnection poll(long timeout) throws InterruptedException;
+
+	/**
+	 * Stops the chooser. Any connections already returned to the chooser are
+	 * closed unless they have been removed from the chooser by calling
+	 * {@link #poll(long)}. Any connections subsequently returned to the
+	 * chooser will also be closed.
+	 */
+	void stop();
+}

bramble-core/src/main/java/org/briarproject/bramble/keyagreement/ConnectionChooserImpl.java

@@ -0,0 +1,112 @@
+package org.briarproject.bramble.keyagreement;
+
+import org.briarproject.bramble.api.keyagreement.KeyAgreementConnection;
+import org.briarproject.bramble.api.lifecycle.IoExecutor;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
+import org.briarproject.bramble.api.system.Clock;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Queue;
+import java.util.concurrent.Callable;
+import java.util.concurrent.Executor;
+import java.util.logging.Logger;
+
+import javax.annotation.Nullable;
+import javax.annotation.concurrent.ThreadSafe;
+import javax.inject.Inject;
+
+import static java.util.logging.Level.INFO;
+
+@NotNullByDefault
+@ThreadSafe
+class ConnectionChooserImpl implements ConnectionChooser {
+
+	private static final Logger LOG =
+			Logger.getLogger(ConnectionChooserImpl.class.getName());
+
+	private final Clock clock;
+	private final Executor ioExecutor;
+	private final Object lock = new Object();
+
+	// The following are locking: lock
+	private boolean stopped = false;
+	private final Queue<KeyAgreementConnection> results = new LinkedList<>();
+
+	@Inject
+	ConnectionChooserImpl(Clock clock, @IoExecutor Executor ioExecutor) {
+		this.clock = clock;
+		this.ioExecutor = ioExecutor;
+	}
+
+	@Override
+	public void submit(Callable<KeyAgreementConnection> task) {
+		ioExecutor.execute(() -> {
+			try {
+				KeyAgreementConnection c = task.call();
+				if (c != null) addResult(c);
+			} catch (Exception e) {
+				if (LOG.isLoggable(INFO)) LOG.info(e.toString());
+			}
+		});
+	}
+
+	@Nullable
+	@Override
+	public KeyAgreementConnection poll(long timeout)
+			throws InterruptedException {
+		long now = clock.currentTimeMillis();
+		long end = now + timeout;
+		synchronized (lock) {
+			while (!stopped && results.isEmpty() && now < end) {
+				lock.wait(end - now);
+				now = clock.currentTimeMillis();
+			}
+			return results.poll();
+		}
+	}
+
+	@Override
+	public void stop() {
+		List<KeyAgreementConnection> unused;
+		synchronized (lock) {
+			unused = new ArrayList<>(results);
+			results.clear();
+			stopped = true;
+			lock.notifyAll();
+		}
+		if (LOG.isLoggable(INFO))
+			LOG.info("Closing " + unused.size() + " unused connections");
+		for (KeyAgreementConnection c : unused) tryToClose(c.getConnection());
+	}
+
+	private void addResult(KeyAgreementConnection c) {
+		if (LOG.isLoggable(INFO))
+			LOG.info("Got connection for " + c.getTransportId());
+		boolean close = false;
+		synchronized (lock) {
+			if (stopped) {
+				close = true;
+			} else {
+				results.add(c);
+				lock.notifyAll();
+			}
+		}
+		if (close) {
+			LOG.info("Already stopped");
+			tryToClose(c.getConnection());
+		}
+	}
+
+	private void tryToClose(DuplexTransportConnection conn) {
+		try {
+			conn.getReader().dispose(false, true);
+			conn.getWriter().dispose(false);
+		} catch (IOException e) {
+			if (LOG.isLoggable(INFO)) LOG.info(e.toString());
+		}
+	}
+}

bramble-core/src/main/java/org/briarproject/bramble/keyagreement/KeyAgreementConnector.java

@@ -13,23 +13,19 @@ import org.briarproject.bramble.api.plugin.PluginManager;
 import org.briarproject.bramble.api.plugin.TransportId;
 import org.briarproject.bramble.api.plugin.duplex.DuplexPlugin;
 import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
-import org.briarproject.bramble.api.system.Clock;
 
 import java.io.IOException;
 import java.io.InputStream;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.concurrent.Callable;
-import java.util.concurrent.CompletionService;
-import java.util.concurrent.ExecutionException;
-import java.util.concurrent.Executor;
-import java.util.concurrent.ExecutorCompletionService;
-import java.util.concurrent.Future;
+import java.util.concurrent.CopyOnWriteArrayList;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.logging.Logger;
 
 import javax.annotation.Nullable;
 
-import static java.util.concurrent.TimeUnit.MILLISECONDS;
 import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
 import static org.briarproject.bramble.api.keyagreement.KeyAgreementConstants.CONNECTION_TIMEOUT;
@@ -45,29 +41,27 @@ class KeyAgreementConnector {
 			Logger.getLogger(KeyAgreementConnector.class.getName());
 
 	private final Callbacks callbacks;
-	private final Clock clock;
 	private final CryptoComponent crypto;
 	private final PluginManager pluginManager;
-	private final CompletionService<KeyAgreementConnection> connect;
+	private final ConnectionChooser connectionChooser;
 
-	private final List<KeyAgreementListener> listeners = new ArrayList<>();
-	private final List<Future<KeyAgreementConnection>> pending =
-			new ArrayList<>();
+	private final List<KeyAgreementListener> listeners =
+			new CopyOnWriteArrayList<>();
+	private final CountDownLatch aliceLatch = new CountDownLatch(1);
+	private final AtomicBoolean waitingSent = new AtomicBoolean(false);
 
-	private volatile boolean connecting = false;
-	private volatile boolean alice = false;
+	private volatile boolean alice = false, stopped = false;
 
-	KeyAgreementConnector(Callbacks callbacks, Clock clock,
+	KeyAgreementConnector(Callbacks callbacks,
 			CryptoComponent crypto, PluginManager pluginManager,
-			Executor ioExecutor) {
+			ConnectionChooser connectionChooser) {
 		this.callbacks = callbacks;
-		this.clock = clock;
 		this.crypto = crypto;
 		this.pluginManager = pluginManager;
-		connect = new ExecutorCompletionService<>(ioExecutor);
+		this.connectionChooser = connectionChooser;
 	}
 
-	public Payload listen(KeyPair localKeyPair) {
+	Payload listen(KeyPair localKeyPair) {
 		LOG.info("Starting BQP listeners");
 		// Derive commitment
 		byte[] commitment = crypto.deriveKeyCommitment(
@@ -80,8 +74,9 @@ class KeyAgreementConnector {
 			if (l != null) {
 				TransportId id = plugin.getId();
 				descriptors.add(new TransportDescriptor(id, l.getDescriptor()));
-				pending.add(connect.submit(new ReadableTask(l.listen())));
+				if (LOG.isLoggable(INFO)) LOG.info("Listening via " + id);
 				listeners.add(l);
+				connectionChooser.submit(new ReadableTask(l::accept));
 			}
 		}
 		return new Payload(commitment, descriptors);
@@ -89,125 +84,92 @@ class KeyAgreementConnector {
 
 	void stopListening() {
 		LOG.info("Stopping BQP listeners");
-		for (KeyAgreementListener l : listeners) {
-			l.close();
-		}
-		listeners.clear();
+		stopped = true;
+		aliceLatch.countDown();
+		for (KeyAgreementListener l : listeners) l.close();
+		connectionChooser.stop();
 	}
 
 	@Nullable
-	public KeyAgreementTransport connect(Payload remotePayload,
-			boolean alice) {
-		// Let the listeners know if we are Alice
-		this.connecting = true;
+	public KeyAgreementTransport connect(Payload remotePayload, boolean alice) {
+		// Let the ReadableTasks know if we are Alice
 		this.alice = alice;
-		long end = clock.currentTimeMillis() + CONNECTION_TIMEOUT;
+		aliceLatch.countDown();
 
 		// Start connecting over supported transports
-		LOG.info("Starting outgoing BQP connections");
+		if (LOG.isLoggable(INFO)) {
+			LOG.info("Starting outgoing BQP connections as "
+					+ (alice ? "Alice" : "Bob"));
+		}
 		for (TransportDescriptor d : remotePayload.getTransportDescriptors()) {
 			Plugin p = pluginManager.getPlugin(d.getId());
 			if (p instanceof DuplexPlugin) {
+				if (LOG.isLoggable(INFO))
+					LOG.info("Connecting via " + d.getId());
 				DuplexPlugin plugin = (DuplexPlugin) p;
-				pending.add(connect.submit(new ReadableTask(
-						new ConnectorTask(plugin, remotePayload.getCommitment(),
-								d.getDescriptor(), end))));
+				byte[] commitment = remotePayload.getCommitment();
+				BdfList descriptor = d.getDescriptor();
+				connectionChooser.submit(new ReadableTask(
+						new ConnectorTask(plugin, commitment, descriptor)));
 			}
 		}
 
 		// Get chosen connection
-		KeyAgreementConnection chosen = null;
 		try {
-			long now = clock.currentTimeMillis();
-			Future<KeyAgreementConnection> f =
-					connect.poll(end - now, MILLISECONDS);
-			if (f == null)
-				return null; // No task completed within the timeout.
-			chosen = f.get();
+			KeyAgreementConnection chosen =
+					connectionChooser.poll(CONNECTION_TIMEOUT);
+			if (chosen == null) return null;
 			return new KeyAgreementTransport(chosen);
 		} catch (InterruptedException e) {
 			LOG.info("Interrupted while waiting for connection");
 			Thread.currentThread().interrupt();
 			return null;
-		} catch (ExecutionException | IOException e) {
+		} catch (IOException e) {
 			if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
 			return null;
 		} finally {
 			stopListening();
-			// Close all other connections
-			closePending(chosen);
 		}
 	}
 
-	private void closePending(@Nullable KeyAgreementConnection chosen) {
-		for (Future<KeyAgreementConnection> f : pending) {
-			try {
-				if (f.cancel(true)) {
-					LOG.info("Cancelled task");
-				} else if (!f.isCancelled()) {
-					KeyAgreementConnection c = f.get();
-					if (c != null && c != chosen)
-						tryToClose(c.getConnection(), false);
-				}
-			} catch (InterruptedException e) {
-				LOG.info("Interrupted while closing sockets");
-				Thread.currentThread().interrupt();
-				return;
-			} catch (ExecutionException e) {
-				if (LOG.isLoggable(INFO)) LOG.info(e.toString());
-			}
-		}
-	}
-
-	private void tryToClose(DuplexTransportConnection conn, boolean exception) {
-		try {
-			if (LOG.isLoggable(INFO))
-				LOG.info("Closing connection, exception: " + exception);
-			conn.getReader().dispose(exception, true);
-			conn.getWriter().dispose(exception);
-		} catch (IOException e) {
-			if (LOG.isLoggable(INFO)) LOG.info(e.toString());
-		}
+	private void waitingForAlice() {
+		if (!waitingSent.getAndSet(true)) callbacks.connectionWaiting();
 	}
 
 	private class ConnectorTask implements Callable<KeyAgreementConnection> {
 
 		private final byte[] commitment;
 		private final BdfList descriptor;
-		private final long end;
 		private final DuplexPlugin plugin;
 
 		private ConnectorTask(DuplexPlugin plugin, byte[] commitment,
-				BdfList descriptor, long end) {
+				BdfList descriptor) {
 			this.plugin = plugin;
 			this.commitment = commitment;
 			this.descriptor = descriptor;
-			this.end = end;
 		}
 
+		@Nullable
 		@Override
 		public KeyAgreementConnection call() throws Exception {
-			// Repeat attempts until we connect, get interrupted, or time out
-			while (true) {
-				long now = clock.currentTimeMillis();
-				if (now > end) throw new IOException();
+			// Repeat attempts until we connect, get stopped, or get interrupted
+			while (!stopped) {
 				DuplexTransportConnection conn =
 						plugin.createKeyAgreementConnection(commitment,
-								descriptor, end - now);
+								descriptor);
 				if (conn != null) {
 					if (LOG.isLoggable(INFO))
-						LOG.info(plugin.getId().getString() +
-								": Outgoing connection");
+						LOG.info(plugin.getId() + ": Outgoing connection");
 					return new KeyAgreementConnection(conn, plugin.getId());
 				}
 				// Wait 2s before retry (to circumvent transient failures)
 				Thread.sleep(2000);
 			}
+			return null;
 		}
 	}
 
-	private class ReadableTask
-			implements Callable<KeyAgreementConnection> {
+	private class ReadableTask implements Callable<KeyAgreementConnection> {
 
 		private final Callable<KeyAgreementConnection> connectionTask;
 
@@ -215,24 +177,23 @@ class KeyAgreementConnector {
 			this.connectionTask = connectionTask;
 		}
 
+		@Nullable
 		@Override
 		public KeyAgreementConnection call() throws Exception {
 			KeyAgreementConnection c = connectionTask.call();
+			if (c == null) return null;
+			aliceLatch.await();
+			if (alice || stopped) return c;
+			// Bob waits here for Alice to scan his QR code, determine her
+			// role, and send her key
 			InputStream in = c.getConnection().getReader().getInputStream();
-			boolean waitingSent = false;
-			while (!alice && in.available() == 0) {
-				if (!waitingSent && connecting && !alice) {
-					// Bob waits here until Alice obtains his payload.
-					callbacks.connectionWaiting();
-					waitingSent = true;
-				}
-				if (LOG.isLoggable(INFO)) {
-					LOG.info(c.getTransportId().getString() +
-							": Waiting for connection");
-				}
-				Thread.sleep(1000);
+			while (!stopped && in.available() == 0) {
+				if (LOG.isLoggable(INFO))
+					LOG.info(c.getTransportId() + ": Waiting for data");
+				waitingForAlice();
+				Thread.sleep(500);
 			}
-			if (!alice && LOG.isLoggable(INFO))
+			if (!stopped && LOG.isLoggable(INFO))
 				LOG.info(c.getTransportId().getString() + ": Data available");
 			return c;
 		}

bramble-core/src/main/java/org/briarproject/bramble/keyagreement/KeyAgreementModule.java

@@ -1,19 +1,10 @@
 package org.briarproject.bramble.keyagreement;
 
-import org.briarproject.bramble.api.crypto.CryptoComponent;
 import org.briarproject.bramble.api.data.BdfReaderFactory;
 import org.briarproject.bramble.api.data.BdfWriterFactory;
-import org.briarproject.bramble.api.event.EventBus;
 import org.briarproject.bramble.api.keyagreement.KeyAgreementTaskFactory;
 import org.briarproject.bramble.api.keyagreement.PayloadEncoder;
 import org.briarproject.bramble.api.keyagreement.PayloadParser;
-import org.briarproject.bramble.api.lifecycle.IoExecutor;
-import org.briarproject.bramble.api.plugin.PluginManager;
-import org.briarproject.bramble.api.system.Clock;
-
-import java.util.concurrent.Executor;
-
-import javax.inject.Singleton;
 
 import dagger.Module;
 import dagger.Provides;
@@ -22,13 +13,9 @@ import dagger.Provides;
 public class KeyAgreementModule {
 
 	@Provides
-	@Singleton
-	KeyAgreementTaskFactory provideKeyAgreementTaskFactory(Clock clock,
-			CryptoComponent crypto, EventBus eventBus,
-			@IoExecutor Executor ioExecutor, PayloadEncoder payloadEncoder,
-			PluginManager pluginManager) {
-		return new KeyAgreementTaskFactoryImpl(clock, crypto, eventBus,
-				ioExecutor, payloadEncoder, pluginManager);
+	KeyAgreementTaskFactory provideKeyAgreementTaskFactory(
+			KeyAgreementTaskFactoryImpl keyAgreementTaskFactory) {
+		return keyAgreementTaskFactory;
 	}
 
 	@Provides
@@ -40,4 +27,10 @@ public class KeyAgreementModule {
 	PayloadParser providePayloadParser(BdfReaderFactory bdfReaderFactory) {
 		return new PayloadParserImpl(bdfReaderFactory);
 	}
+
+	@Provides
+	ConnectionChooser provideConnectionChooser(
+			ConnectionChooserImpl connectionChooser) {
+		return connectionChooser;
+	}
 }

bramble-core/src/main/java/org/briarproject/bramble/keyagreement/KeyAgreementProtocol.java

@@ -89,7 +89,8 @@ class KeyAgreementProtocol {
 			byte[] theirPublicKey;
 			if (alice) {
 				sendKey();
-				// Alice waits here until Bob obtains her payload.
+				// Alice waits here for Bob to scan her QR code, determine his
+				// role, receive her key and respond with his key
 				callbacks.connectionWaiting();
 				theirPublicKey = receiveKey();
 			} else {

bramble-core/src/main/java/org/briarproject/bramble/keyagreement/KeyAgreementTaskFactoryImpl.java

@@ -5,42 +5,37 @@ import org.briarproject.bramble.api.event.EventBus;
 import org.briarproject.bramble.api.keyagreement.KeyAgreementTask;
 import org.briarproject.bramble.api.keyagreement.KeyAgreementTaskFactory;
 import org.briarproject.bramble.api.keyagreement.PayloadEncoder;
-import org.briarproject.bramble.api.lifecycle.IoExecutor;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.PluginManager;
-import org.briarproject.bramble.api.system.Clock;
-
-import java.util.concurrent.Executor;
 
 import javax.annotation.concurrent.Immutable;
 import javax.inject.Inject;
+import javax.inject.Provider;
 
 @Immutable
 @NotNullByDefault
 class KeyAgreementTaskFactoryImpl implements KeyAgreementTaskFactory {
 
-	private final Clock clock;
 	private final CryptoComponent crypto;
 	private final EventBus eventBus;
-	private final Executor ioExecutor;
 	private final PayloadEncoder payloadEncoder;
 	private final PluginManager pluginManager;
+	private final Provider<ConnectionChooser> connectionChooserProvider;
 
 	@Inject
-	KeyAgreementTaskFactoryImpl(Clock clock, CryptoComponent crypto,
-			EventBus eventBus, @IoExecutor Executor ioExecutor,
-			PayloadEncoder payloadEncoder, PluginManager pluginManager) {
-		this.clock = clock;
+	KeyAgreementTaskFactoryImpl(CryptoComponent crypto, EventBus eventBus,
+			PayloadEncoder payloadEncoder, PluginManager pluginManager,
+			Provider<ConnectionChooser> connectionChooserProvider) {
 		this.crypto = crypto;
 		this.eventBus = eventBus;
-		this.ioExecutor = ioExecutor;
 		this.payloadEncoder = payloadEncoder;
 		this.pluginManager = pluginManager;
+		this.connectionChooserProvider = connectionChooserProvider;
 	}
 
 	@Override
 	public KeyAgreementTask createTask() {
-		return new KeyAgreementTaskImpl(clock, crypto, eventBus, payloadEncoder,
-				pluginManager, ioExecutor);
+		return new KeyAgreementTaskImpl(crypto, eventBus, payloadEncoder,
+				pluginManager, connectionChooserProvider.get());
 	}
 }

bramble-core/src/main/java/org/briarproject/bramble/keyagreement/KeyAgreementTaskImpl.java

@@ -17,19 +17,16 @@ import org.briarproject.bramble.api.keyagreement.event.KeyAgreementWaitingEvent;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.bramble.api.plugin.PluginManager;
-import org.briarproject.bramble.api.system.Clock;
 
 import java.io.IOException;
-import java.util.concurrent.Executor;
 import java.util.logging.Logger;
 
 import static java.util.logging.Level.WARNING;
 
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
-class KeyAgreementTaskImpl extends Thread implements
-		KeyAgreementTask, KeyAgreementConnector.Callbacks,
-		KeyAgreementProtocol.Callbacks {
+class KeyAgreementTaskImpl extends Thread implements KeyAgreementTask,
+		KeyAgreementProtocol.Callbacks, KeyAgreementConnector.Callbacks {
 
 	private static final Logger LOG =
 			Logger.getLogger(KeyAgreementTaskImpl.class.getName());
@@ -43,15 +40,15 @@ class KeyAgreementTaskImpl extends Thread implements
 	private Payload localPayload;
 	private Payload remotePayload;
 
-	KeyAgreementTaskImpl(Clock clock, CryptoComponent crypto,
-			EventBus eventBus, PayloadEncoder payloadEncoder,
-			PluginManager pluginManager, Executor ioExecutor) {
+	KeyAgreementTaskImpl(CryptoComponent crypto, EventBus eventBus,
+			PayloadEncoder payloadEncoder, PluginManager pluginManager,
+			ConnectionChooser connectionChooser) {
 		this.crypto = crypto;
 		this.eventBus = eventBus;
 		this.payloadEncoder = payloadEncoder;
 		localKeyPair = crypto.generateAgreementKeyPair();
-		connector = new KeyAgreementConnector(this, clock, crypto,
-				pluginManager, ioExecutor);
+		connector = new KeyAgreementConnector(this, crypto, pluginManager,
+				connectionChooser);
 	}
 
 	@Override
@@ -65,10 +62,8 @@ class KeyAgreementTaskImpl extends Thread implements
 	@Override
 	public synchronized void stopListening() {
 		if (localPayload != null) {
-			if (remotePayload == null)
-				connector.stopListening();
-			else
-				interrupt();
+			if (remotePayload == null) connector.stopListening();
+			else interrupt();
 		}
 	}
 

bramble-core/src/main/java/org/briarproject/bramble/lifecycle/LifecycleManagerImpl.java

@@ -2,8 +2,11 @@ package org.briarproject.bramble.lifecycle;
 
 import org.briarproject.bramble.api.crypto.CryptoComponent;
 import org.briarproject.bramble.api.crypto.KeyPair;
+import org.briarproject.bramble.api.db.DataTooNewException;
+import org.briarproject.bramble.api.db.DataTooOldException;
 import org.briarproject.bramble.api.db.DatabaseComponent;
 import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.db.MigrationListener;
 import org.briarproject.bramble.api.db.Transaction;
 import org.briarproject.bramble.api.event.EventBus;
 import org.briarproject.bramble.api.identity.AuthorFactory;
@@ -12,7 +15,7 @@ import org.briarproject.bramble.api.identity.LocalAuthor;
 import org.briarproject.bramble.api.lifecycle.LifecycleManager;
 import org.briarproject.bramble.api.lifecycle.Service;
 import org.briarproject.bramble.api.lifecycle.ServiceException;
-import org.briarproject.bramble.api.lifecycle.event.ShutdownEvent;
+import org.briarproject.bramble.api.lifecycle.event.LifecycleEvent;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.sync.Client;
 
@@ -29,14 +32,21 @@ import javax.inject.Inject;
 
 import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
+import static org.briarproject.bramble.api.lifecycle.LifecycleManager.LifecycleState.MIGRATING_DATABASE;
+import static org.briarproject.bramble.api.lifecycle.LifecycleManager.LifecycleState.RUNNING;
+import static org.briarproject.bramble.api.lifecycle.LifecycleManager.LifecycleState.STARTING;
+import static org.briarproject.bramble.api.lifecycle.LifecycleManager.LifecycleState.STARTING_SERVICES;
+import static org.briarproject.bramble.api.lifecycle.LifecycleManager.LifecycleState.STOPPING;
 import static org.briarproject.bramble.api.lifecycle.LifecycleManager.StartResult.ALREADY_RUNNING;
+import static org.briarproject.bramble.api.lifecycle.LifecycleManager.StartResult.DATA_TOO_NEW_ERROR;
+import static org.briarproject.bramble.api.lifecycle.LifecycleManager.StartResult.DATA_TOO_OLD_ERROR;
 import static org.briarproject.bramble.api.lifecycle.LifecycleManager.StartResult.DB_ERROR;
 import static org.briarproject.bramble.api.lifecycle.LifecycleManager.StartResult.SERVICE_ERROR;
 import static org.briarproject.bramble.api.lifecycle.LifecycleManager.StartResult.SUCCESS;
 
 @ThreadSafe
 @NotNullByDefault
-class LifecycleManagerImpl implements LifecycleManager {
+class LifecycleManagerImpl implements LifecycleManager, MigrationListener {
 
 	private static final Logger LOG =
 			Logger.getLogger(LifecycleManagerImpl.class.getName());
@@ -54,6 +64,8 @@ class LifecycleManagerImpl implements LifecycleManager {
 	private final CountDownLatch startupLatch = new CountDownLatch(1);
 	private final CountDownLatch shutdownLatch = new CountDownLatch(1);
 
+	private volatile LifecycleState state = STARTING;
+
 	@Inject
 	LifecycleManagerImpl(DatabaseComponent db, EventBus eventBus,
 			CryptoComponent crypto, AuthorFactory authorFactory,
@@ -119,7 +131,7 @@ class LifecycleManagerImpl implements LifecycleManager {
 			LOG.info("Starting services");
 			long start = System.currentTimeMillis();
 
-			boolean reopened = db.open();
+			boolean reopened = db.open(this);
 			long duration = System.currentTimeMillis() - start;
 			if (LOG.isLoggable(INFO)) {
 				if (reopened)
@@ -131,7 +143,10 @@ class LifecycleManagerImpl implements LifecycleManager {
 				registerLocalAuthor(createLocalAuthor(nickname));
 			}
 
+			state = STARTING_SERVICES;
 			dbLatch.countDown();
+			eventBus.broadcast(new LifecycleEvent(STARTING_SERVICES));
+
 			Transaction txn = db.startTransaction(false);
 			try {
 				for (Client c : clients) {
@@ -157,8 +172,17 @@ class LifecycleManagerImpl implements LifecycleManager {
 							+ " took " + duration + " ms");
 				}
 			}
+
+			state = RUNNING;
 			startupLatch.countDown();
+			eventBus.broadcast(new LifecycleEvent(RUNNING));
 			return SUCCESS;
+		} catch (DataTooOldException e) {
+			if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
+			return DATA_TOO_OLD_ERROR;
+		} catch (DataTooNewException e) {
+			if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
+			return DATA_TOO_NEW_ERROR;
 		} catch (DbException e) {
 			if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
 			return DB_ERROR;
@@ -170,6 +194,12 @@ class LifecycleManagerImpl implements LifecycleManager {
 		}
 	}
 
+	@Override
+	public void onMigrationRun() {
+		state = MIGRATING_DATABASE;
+		eventBus.broadcast(new LifecycleEvent(MIGRATING_DATABASE));
+	}
+
 	@Override
 	public void stopServices() {
 		try {
@@ -180,7 +210,8 @@ class LifecycleManagerImpl implements LifecycleManager {
 		}
 		try {
 			LOG.info("Stopping services");
-			eventBus.broadcast(new ShutdownEvent());
+			state = STOPPING;
+			eventBus.broadcast(new LifecycleEvent(STOPPING));
 			for (Service s : services) {
 				long start = System.currentTimeMillis();
 				s.stopService();
@@ -225,4 +256,8 @@ class LifecycleManagerImpl implements LifecycleManager {
 		shutdownLatch.await();
 	}
 
+	@Override
+	public LifecycleState getLifecycleState() {
+		return state;
+	}
 }

bramble-core/src/main/java/org/briarproject/bramble/plugin/Poller.java

@@ -16,6 +16,7 @@ import org.briarproject.bramble.api.plugin.duplex.DuplexPlugin;
 import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
 import org.briarproject.bramble.api.plugin.event.ConnectionClosedEvent;
 import org.briarproject.bramble.api.plugin.event.ConnectionOpenedEvent;
+import org.briarproject.bramble.api.plugin.event.TransportDisabledEvent;
 import org.briarproject.bramble.api.plugin.event.TransportEnabledEvent;
 import org.briarproject.bramble.api.plugin.simplex.SimplexPlugin;
 import org.briarproject.bramble.api.system.Clock;
@@ -25,6 +26,7 @@ import java.security.SecureRandom;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.concurrent.Executor;
+import java.util.concurrent.Future;
 import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.locks.Lock;
 import java.util.concurrent.locks.ReentrantLock;
@@ -50,7 +52,7 @@ class Poller implements EventListener {
 	private final SecureRandom random;
 	private final Clock clock;
 	private final Lock lock;
-	private final Map<TransportId, PollTask> tasks; // Locking: lock
+	private final Map<TransportId, ScheduledPollTask> tasks; // Locking: lock
 
 	@Inject
 	Poller(@IoExecutor Executor ioExecutor,
@@ -93,6 +95,10 @@ class Poller implements EventListener {
 			TransportEnabledEvent t = (TransportEnabledEvent) e;
 			// Poll the newly enabled transport
 			pollNow(t.getTransportId());
+		} else if (e instanceof TransportDisabledEvent) {
+			TransportDisabledEvent t = (TransportDisabledEvent) e;
+			// Cancel polling for the disabled transport
+			cancel(t.getTransportId());
 		}
 	}
 
@@ -151,18 +157,31 @@ class Poller implements EventListener {
 		TransportId t = p.getId();
 		lock.lock();
 		try {
-			PollTask scheduled = tasks.get(t);
-			if (scheduled == null || due < scheduled.due) {
+			ScheduledPollTask scheduled = tasks.get(t);
+			if (scheduled == null || due < scheduled.task.due) {
+				// If a later task exists, cancel it. If it's already started
+				// it will abort safely when it finds it's been replaced
+				if (scheduled != null) scheduled.future.cancel(false);
 				PollTask task = new PollTask(p, due, randomiseNext);
-				tasks.put(t, task);
-				scheduler.schedule(
+				Future future = scheduler.schedule(
 						() -> ioExecutor.execute(task), delay, MILLISECONDS);
+				tasks.put(t, new ScheduledPollTask(task, future));
 			}
 		} finally {
 			lock.unlock();
 		}
 	}
 
+	private void cancel(TransportId t) {
+		lock.lock();
+		try {
+			ScheduledPollTask scheduled = tasks.remove(t);
+			if (scheduled != null) scheduled.future.cancel(false);
+		} finally {
+			lock.unlock();
+		}
+	}
+
 	@IoExecutor
 	private void poll(Plugin p) {
 		TransportId t = p.getId();
@@ -170,6 +189,17 @@ class Poller implements EventListener {
 		p.poll(connectionRegistry.getConnectedContacts(t));
 	}
 
+	private class ScheduledPollTask {
+
+		private final PollTask task;
+		private final Future future;
+
+		private ScheduledPollTask(PollTask task, Future future) {
+			this.task = task;
+			this.future = future;
+		}
+	}
+
 	private class PollTask implements Runnable {
 
 		private final Plugin plugin;
@@ -188,7 +218,9 @@ class Poller implements EventListener {
 			lock.lock();
 			try {
 				TransportId t = plugin.getId();
-				if (tasks.get(t) != this) return; // Replaced by another task
+				ScheduledPollTask scheduled = tasks.get(t);
+				if (scheduled != null && scheduled.task != this)
+					return; // Replaced by another task
 				tasks.remove(t);
 			} finally {
 				lock.unlock();

bramble-core/src/main/java/org/briarproject/bramble/plugin/bluetooth/BluetoothPlugin.java

@@ -3,6 +3,8 @@ package org.briarproject.bramble.plugin.bluetooth;
 import org.briarproject.bramble.api.FormatException;
 import org.briarproject.bramble.api.contact.ContactId;
 import org.briarproject.bramble.api.data.BdfList;
+import org.briarproject.bramble.api.event.Event;
+import org.briarproject.bramble.api.event.EventListener;
 import org.briarproject.bramble.api.keyagreement.KeyAgreementConnection;
 import org.briarproject.bramble.api.keyagreement.KeyAgreementListener;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
@@ -13,8 +15,11 @@ import org.briarproject.bramble.api.plugin.TransportId;
 import org.briarproject.bramble.api.plugin.duplex.DuplexPlugin;
 import org.briarproject.bramble.api.plugin.duplex.DuplexPluginCallback;
 import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
+import org.briarproject.bramble.api.plugin.event.BluetoothEnabledEvent;
+import org.briarproject.bramble.api.plugin.event.DisableBluetoothEvent;
+import org.briarproject.bramble.api.plugin.event.EnableBluetoothEvent;
 import org.briarproject.bramble.api.properties.TransportProperties;
-import org.briarproject.bramble.util.OsUtils;
+import org.briarproject.bramble.api.settings.event.SettingsUpdatedEvent;
 import org.briarproject.bramble.util.StringUtils;
 
 import java.io.IOException;
@@ -23,30 +28,25 @@ import java.util.Collection;
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.UUID;
-import java.util.concurrent.Callable;
 import java.util.concurrent.Executor;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.logging.Logger;
 
 import javax.annotation.Nullable;
-import javax.bluetooth.BluetoothStateException;
-import javax.bluetooth.LocalDevice;
-import javax.microedition.io.Connector;
-import javax.microedition.io.StreamConnection;
-import javax.microedition.io.StreamConnectionNotifier;
 
 import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
-import static javax.bluetooth.DiscoveryAgent.GIAC;
 import static org.briarproject.bramble.api.keyagreement.KeyAgreementConstants.TRANSPORT_ID_BLUETOOTH;
 import static org.briarproject.bramble.api.plugin.BluetoothConstants.ID;
+import static org.briarproject.bramble.api.plugin.BluetoothConstants.PREF_BT_ENABLE;
 import static org.briarproject.bramble.api.plugin.BluetoothConstants.PROP_ADDRESS;
 import static org.briarproject.bramble.api.plugin.BluetoothConstants.PROP_UUID;
 import static org.briarproject.bramble.api.plugin.BluetoothConstants.UUID_BYTES;
+import static org.briarproject.bramble.util.PrivacyUtils.scrubMacAddress;
 
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
-class BluetoothPlugin implements DuplexPlugin {
+abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 
 	private static final Logger LOG =
 			Logger.getLogger(BluetoothPlugin.class.getName());
@@ -58,9 +58,38 @@ class BluetoothPlugin implements DuplexPlugin {
 	private final int maxLatency;
 	private final AtomicBoolean used = new AtomicBoolean(false);
 
-	private volatile boolean running = false;
-	private volatile StreamConnectionNotifier socket = null;
-	private volatile LocalDevice localDevice = null;
+	private volatile boolean running = false, contactConnections = false;
+	private volatile String contactConnectionsUuid = null;
+	private volatile SS socket = null;
+
+	abstract void initialiseAdapter() throws IOException;
+
+	abstract boolean isAdapterEnabled();
+
+	abstract void enableAdapter();
+
+	abstract void disableAdapterIfEnabledByUs();
+
+	abstract void setEnabledByUs();
+
+	/**
+	 * Returns the local Bluetooth address, or null if no valid address can
+	 * be found.
+	 */
+	@Nullable
+	abstract String getBluetoothAddress();
+
+	abstract SS openServerSocket(String uuid) throws IOException;
+
+	abstract void tryToClose(@Nullable SS ss);
+
+	abstract DuplexTransportConnection acceptConnection(SS ss)
+			throws IOException;
+
+	abstract boolean isValidAddress(String address);
+
+	abstract DuplexTransportConnection connectTo(String address, String uuid)
+			throws IOException;
 
 	BluetoothPlugin(Executor ioExecutor, SecureRandom secureRandom,
 			Backoff backoff, DuplexPluginCallback callback, int maxLatency) {
@@ -71,6 +100,19 @@ class BluetoothPlugin implements DuplexPlugin {
 		this.maxLatency = maxLatency;
 	}
 
+	void onAdapterEnabled() {
+		LOG.info("Bluetooth enabled");
+		// We may not have been able to get the local address before
+		ioExecutor.execute(this::updateProperties);
+		if (shouldAllowContactConnections()) bind();
+	}
+
+	void onAdapterDisabled() {
+		LOG.info("Bluetooth disabled");
+		tryToClose(socket);
+		callback.transportDisabled();
+	}
+
 	@Override
 	public TransportId getId() {
 		return ID;
@@ -90,107 +132,103 @@ class BluetoothPlugin implements DuplexPlugin {
 	@Override
 	public void start() throws PluginException {
 		if (used.getAndSet(true)) throw new IllegalStateException();
-		// Initialise the Bluetooth stack
 		try {
-			localDevice = LocalDevice.getLocalDevice();
-		} catch (UnsatisfiedLinkError e) {
-			// On Linux the user may need to install libbluetooth-dev
-			if (OsUtils.isLinux())
-				callback.showMessage("BLUETOOTH_INSTALL_LIBS");
-			throw new PluginException(e);
-		} catch (BluetoothStateException e) {
+			initialiseAdapter();
+		} catch (IOException e) {
 			throw new PluginException(e);
 		}
-		if (LOG.isLoggable(INFO))
-			LOG.info("Local address " + localDevice.getBluetoothAddress());
+		updateProperties();
 		running = true;
-		bind();
+		loadSettings();
+		if (shouldAllowContactConnections()) {
+			if (isAdapterEnabled()) bind();
+			else enableAdapter();
+		}
+	}
+
+	private void loadSettings() {
+		contactConnections =
+				callback.getSettings().getBoolean(PREF_BT_ENABLE, false);
+	}
+
+	private boolean shouldAllowContactConnections() {
+		return contactConnections;
 	}
 
 	private void bind() {
 		ioExecutor.execute(() -> {
-			if (!running) return;
-			// Advertise the Bluetooth address to contacts
-			TransportProperties p = new TransportProperties();
-			p.put(PROP_ADDRESS, localDevice.getBluetoothAddress());
-			callback.mergeLocalProperties(p);
+			if (!isRunning() || !shouldAllowContactConnections()) return;
 			// Bind a server socket to accept connections from contacts
-			String url = makeUrl("localhost", getUuid());
-			StreamConnectionNotifier ss;
+			SS ss;
 			try {
-				ss = (StreamConnectionNotifier) Connector.open(url);
+				ss = openServerSocket(contactConnectionsUuid);
 			} catch (IOException e) {
-				if (LOG.isLoggable(WARNING))
-					LOG.log(WARNING, e.toString(), e);
+				if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
 				return;
 			}
-			if (!running) {
+			if (!isRunning() || !shouldAllowContactConnections()) {
 				tryToClose(ss);
 				return;
 			}
 			socket = ss;
 			backoff.reset();
 			callback.transportEnabled();
-			acceptContactConnections(ss);
+			acceptContactConnections();
 		});
 	}
 
-	private String makeUrl(String address, String uuid) {
-		return "btspp://" + address + ":" + uuid + ";name=RFCOMM";
-	}
-
-	private String getUuid() {
-		String uuid = callback.getLocalProperties().get(PROP_UUID);
+	private void updateProperties() {
+		TransportProperties p = callback.getLocalProperties();
+		String address = p.get(PROP_ADDRESS);
+		String uuid = p.get(PROP_UUID);
+		boolean changed = false;
+		if (address == null) {
+			address = getBluetoothAddress();
+			if (LOG.isLoggable(INFO))
+				LOG.info("Local address " + scrubMacAddress(address));
+			if (!StringUtils.isNullOrEmpty(address)) {
+				p.put(PROP_ADDRESS, address);
+				changed = true;
+			}
+		}
 		if (uuid == null) {
 			byte[] random = new byte[UUID_BYTES];
 			secureRandom.nextBytes(random);
 			uuid = UUID.nameUUIDFromBytes(random).toString();
-			TransportProperties p = new TransportProperties();
 			p.put(PROP_UUID, uuid);
-			callback.mergeLocalProperties(p);
+			changed = true;
 		}
-		return uuid;
+		contactConnectionsUuid = uuid;
+		if (changed) callback.mergeLocalProperties(p);
 	}
 
-	private void tryToClose(@Nullable StreamConnectionNotifier ss) {
-		try {
-			if (ss != null) ss.close();
-		} catch (IOException e) {
-			if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
-		} finally {
-			callback.transportDisabled();
-		}
-	}
-
-	private void acceptContactConnections(StreamConnectionNotifier ss) {
+	private void acceptContactConnections() {
 		while (true) {
-			StreamConnection s;
+			DuplexTransportConnection conn;
 			try {
-				s = ss.acceptAndOpen();
+				conn = acceptConnection(socket);
 			} catch (IOException e) {
 				// This is expected when the socket is closed
 				if (LOG.isLoggable(INFO)) LOG.info(e.toString());
 				return;
 			}
 			backoff.reset();
-			callback.incomingConnectionCreated(wrapSocket(s));
+			callback.incomingConnectionCreated(conn);
 			if (!running) return;
 		}
 	}
 
-	private DuplexTransportConnection wrapSocket(StreamConnection s) {
-		return new BluetoothTransportConnection(this, s);
-	}
-
 	@Override
 	public void stop() {
 		running = false;
 		tryToClose(socket);
+		callback.transportDisabled();
+		disableAdapterIfEnabledByUs();
 	}
 
 	@Override
 	public boolean isRunning() {
-		return running;
+		return running && isAdapterEnabled();
 	}
 
 	@Override
@@ -205,7 +243,7 @@ class BluetoothPlugin implements DuplexPlugin {
 
 	@Override
 	public void poll(Collection<ContactId> connected) {
-		if (!running) return;
+		if (!isRunning() || !shouldAllowContactConnections()) return;
 		backoff.increment();
 		// Try to connect to known devices in parallel
 		Map<ContactId, TransportProperties> remote =
@@ -218,41 +256,56 @@ class BluetoothPlugin implements DuplexPlugin {
 			String uuid = e.getValue().get(PROP_UUID);
 			if (StringUtils.isNullOrEmpty(uuid)) continue;
 			ioExecutor.execute(() -> {
-				if (!running) return;
-				StreamConnection s = connect(makeUrl(address, uuid));
-				if (s != null) {
+				if (!isRunning() || !shouldAllowContactConnections()) return;
+				DuplexTransportConnection conn = connect(address, uuid);
+				if (conn != null) {
 					backoff.reset();
-					callback.outgoingConnectionCreated(c, wrapSocket(s));
+					callback.outgoingConnectionCreated(c, conn);
 				}
 			});
 		}
 	}
 
 	@Nullable
-	private StreamConnection connect(String url) {
-		if (LOG.isLoggable(INFO)) LOG.info("Connecting to " + url);
+	private DuplexTransportConnection connect(String address, String uuid) {
+		// Validate the address
+		if (!isValidAddress(address)) {
+			if (LOG.isLoggable(WARNING))
+				// Not scrubbing here to be able to figure out the problem
+				LOG.warning("Invalid address " + address);
+			return null;
+		}
+		// Validate the UUID
 		try {
-			StreamConnection s = (StreamConnection) Connector.open(url);
-			if (LOG.isLoggable(INFO)) LOG.info("Connected to " + url);
-			return s;
+			//noinspection ResultOfMethodCallIgnored
+			UUID.fromString(uuid);
+		} catch (IllegalArgumentException e) {
+			if (LOG.isLoggable(WARNING)) LOG.warning("Invalid UUID " + uuid);
+			return null;
+		}
+		if (LOG.isLoggable(INFO))
+			LOG.info("Connecting to " + scrubMacAddress(address));
+		try {
+			DuplexTransportConnection conn = connectTo(address, uuid);
+			if (LOG.isLoggable(INFO))
+				LOG.info("Connected to " + scrubMacAddress(address));
+			return conn;
 		} catch (IOException e) {
-			if (LOG.isLoggable(INFO)) LOG.info("Could not connect to " + url);
+			if (LOG.isLoggable(INFO))
+				LOG.info("Could not connect to " + scrubMacAddress(address));
 			return null;
 		}
 	}
 
 	@Override
 	public DuplexTransportConnection createConnection(ContactId c) {
-		if (!running) return null;
+		if (!isRunning() || !shouldAllowContactConnections()) return null;
 		TransportProperties p = callback.getRemoteProperties(c);
 		String address = p.get(PROP_ADDRESS);
 		if (StringUtils.isNullOrEmpty(address)) return null;
 		String uuid = p.get(PROP_UUID);
 		if (StringUtils.isNullOrEmpty(uuid)) return null;
-		String url = makeUrl(address, uuid);
-		StreamConnection s = connect(url);
-		if (s == null) return null;
-		return new BluetoothTransportConnection(this, s);
+		return connect(address, uuid);
 	}
 
 	@Override
@@ -262,35 +315,34 @@ class BluetoothPlugin implements DuplexPlugin {
 
 	@Override
 	public KeyAgreementListener createKeyAgreementListener(byte[] commitment) {
-		if (!running) return null;
+		if (!isRunning()) return null;
+		// There's no point listening if we can't discover our own address
+		String address = getBluetoothAddress();
+		if (address == null) return null;
 		// No truncation necessary because COMMIT_LENGTH = 16
 		String uuid = UUID.nameUUIDFromBytes(commitment).toString();
 		if (LOG.isLoggable(INFO)) LOG.info("Key agreement UUID " + uuid);
-		String url = makeUrl("localhost", uuid);
-		// Make the device discoverable if possible
-		makeDeviceDiscoverable();
-		// Bind a server socket for receiving key agreementconnections
-		StreamConnectionNotifier ss;
+		// Bind a server socket for receiving key agreement connections
+		SS ss;
 		try {
-			ss = (StreamConnectionNotifier) Connector.open(url);
+			ss = openServerSocket(uuid);
 		} catch (IOException e) {
 			if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
 			return null;
 		}
-		if (!running) {
+		if (!isRunning()) {
 			tryToClose(ss);
 			return null;
 		}
 		BdfList descriptor = new BdfList();
 		descriptor.add(TRANSPORT_ID_BLUETOOTH);
-		String address = localDevice.getBluetoothAddress();
 		descriptor.add(StringUtils.macToBytes(address));
 		return new BluetoothKeyAgreementListener(descriptor, ss);
 	}
 
 	@Override
 	public DuplexTransportConnection createKeyAgreementConnection(
-			byte[] commitment, BdfList descriptor, long timeout) {
+			byte[] commitment, BdfList descriptor) {
 		if (!isRunning()) return null;
 		String address;
 		try {
@@ -303,10 +355,7 @@ class BluetoothPlugin implements DuplexPlugin {
 		String uuid = UUID.nameUUIDFromBytes(commitment).toString();
 		if (LOG.isLoggable(INFO))
 			LOG.info("Connecting to key agreement UUID " + uuid);
-		String url = makeUrl(address, uuid);
-		StreamConnection s = connect(url);
-		if (s == null) return null;
-		return new BluetoothTransportConnection(this, s);
+		return connect(address, uuid);
 	}
 
 	private String parseAddress(BdfList descriptor) throws FormatException {
@@ -315,44 +364,56 @@ class BluetoothPlugin implements DuplexPlugin {
 		return StringUtils.macToString(mac);
 	}
 
-	private void makeDeviceDiscoverable() {
-		// Try to make the device discoverable (requires root on Linux)
-		try {
-			localDevice.setDiscoverable(GIAC);
-		} catch (BluetoothStateException e) {
-			if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
+	@Override
+	public void eventOccurred(Event e) {
+		if (e instanceof EnableBluetoothEvent) {
+			ioExecutor.execute(this::enableAdapter);
+		} else if (e instanceof DisableBluetoothEvent) {
+			ioExecutor.execute(this::disableAdapterIfEnabledByUs);
+		} else if (e instanceof BluetoothEnabledEvent) {
+			setEnabledByUs();
+		} else if (e instanceof SettingsUpdatedEvent) {
+			SettingsUpdatedEvent s = (SettingsUpdatedEvent) e;
+			if (s.getNamespace().equals(ID.getString()))
+				ioExecutor.execute(this::onSettingsUpdated);
+		}
+	}
+
+	private void onSettingsUpdated() {
+		boolean wasAllowed = shouldAllowContactConnections();
+		loadSettings();
+		boolean isAllowed = shouldAllowContactConnections();
+		if (wasAllowed && !isAllowed) {
+			LOG.info("Contact connections disabled");
+			tryToClose(socket);
+			callback.transportDisabled();
+			disableAdapterIfEnabledByUs();
+		} else if (!wasAllowed && isAllowed) {
+			LOG.info("Contact connections enabled");
+			if (isAdapterEnabled()) bind();
+			else enableAdapter();
 		}
 	}
 
 	private class BluetoothKeyAgreementListener extends KeyAgreementListener {
 
-		private final StreamConnectionNotifier ss;
+		private final SS ss;
 
-		private BluetoothKeyAgreementListener(BdfList descriptor,
-				StreamConnectionNotifier ss) {
+		private BluetoothKeyAgreementListener(BdfList descriptor, SS ss) {
 			super(descriptor);
 			this.ss = ss;
 		}
 
 		@Override
-		public Callable<KeyAgreementConnection> listen() {
-			return () -> {
-				StreamConnection s = ss.acceptAndOpen();
-				if (LOG.isLoggable(INFO))
-					LOG.info(ID.getString() + ": Incoming connection");
-				return new KeyAgreementConnection(
-						new BluetoothTransportConnection(
-								BluetoothPlugin.this, s), ID);
-			};
+		public KeyAgreementConnection accept() throws IOException {
+			DuplexTransportConnection conn = acceptConnection(ss);
+			if (LOG.isLoggable(INFO)) LOG.info(ID + ": Incoming connection");
+			return new KeyAgreementConnection(conn, ID);
 		}
 
 		@Override
 		public void close() {
-			try {
-				ss.close();
-			} catch (IOException e) {
-				if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
-			}
+			tryToClose(ss);
 		}
 	}
 }

bramble-core/src/main/java/org/briarproject/bramble/plugin/tcp/LanTcpPlugin.java

@@ -23,9 +23,8 @@ import java.net.SocketAddress;
 import java.net.UnknownHostException;
 import java.util.ArrayList;
 import java.util.Collections;
-import java.util.LinkedList;
+import java.util.Comparator;
 import java.util.List;
-import java.util.concurrent.Callable;
 import java.util.concurrent.Executor;
 import java.util.logging.Logger;
 
@@ -44,6 +43,9 @@ class LanTcpPlugin extends TcpPlugin {
 	private static final Logger LOG =
 			Logger.getLogger(LanTcpPlugin.class.getName());
 
+	private static final LanAddressComparator ADDRESS_COMPARATOR =
+			new LanAddressComparator();
+
 	private static final int MAX_ADDRESSES = 4;
 	private static final String SEPARATOR = ",";
 
@@ -63,19 +65,18 @@ class LanTcpPlugin extends TcpPlugin {
 		TransportProperties p = callback.getLocalProperties();
 		String oldIpPorts = p.get(PROP_IP_PORTS);
 		List<InetSocketAddress> olds = parseSocketAddresses(oldIpPorts);
-		List<InetSocketAddress> locals = new LinkedList<>();
+		List<InetSocketAddress> locals = new ArrayList<>();
 		for (InetAddress local : getLocalIpAddresses()) {
 			if (isAcceptableAddress(local)) {
 				// If this is the old address, try to use the same port
 				for (InetSocketAddress old : olds) {
-					if (old.getAddress().equals(local)) {
-						int port = old.getPort();
-						locals.add(0, new InetSocketAddress(local, port));
-					}
+					if (old.getAddress().equals(local))
+						locals.add(new InetSocketAddress(local, old.getPort()));
 				}
 				locals.add(new InetSocketAddress(local, 0));
 			}
 		}
+		Collections.sort(locals, ADDRESS_COMPARATOR);
 		return locals;
 	}
 
@@ -153,17 +154,39 @@ class LanTcpPlugin extends TcpPlugin {
 	// Package access for testing
 	boolean addressesAreOnSameLan(byte[] localIp, byte[] remoteIp) {
 		// 10.0.0.0/8
-		if (localIp[0] == 10) return remoteIp[0] == 10;
+		if (isPrefix10(localIp)) return isPrefix10(remoteIp);
 		// 172.16.0.0/12
-		if (localIp[0] == (byte) 172 && (localIp[1] & 0xF0) == 16)
-			return remoteIp[0] == (byte) 172 && (remoteIp[1] & 0xF0) == 16;
+		if (isPrefix172(localIp)) return isPrefix172(remoteIp);
 		// 192.168.0.0/16
-		if (localIp[0] == (byte) 192 && localIp[1] == (byte) 168)
-			return remoteIp[0] == (byte) 192 && remoteIp[1] == (byte) 168;
+		if (isPrefix192(localIp)) return isPrefix192(remoteIp);
 		// Unrecognised prefix - may be compatible
 		return true;
 	}
 
+	private static boolean isPrefix10(byte[] ipv4) {
+		return ipv4[0] == 10;
+	}
+
+	private static boolean isPrefix172(byte[] ipv4) {
+		return ipv4[0] == (byte) 172 && (ipv4[1] & 0xF0) == 16;
+	}
+
+	private static boolean isPrefix192(byte[] ipv4) {
+		return ipv4[0] == (byte) 192 && ipv4[1] == (byte) 168;
+	}
+
+	// Returns the prefix length for an RFC 1918 address, or 0 for any other
+	// address
+	private static int getRfc1918PrefixLength(InetAddress addr) {
+		if (!(addr instanceof Inet4Address)) return 0;
+		if (!addr.isSiteLocalAddress()) return 0;
+		byte[] ipv4 = addr.getAddress();
+		if (isPrefix10(ipv4)) return 8;
+		if (isPrefix172(ipv4)) return 12;
+		if (isPrefix192(ipv4)) return 16;
+		return 0;
+	}
+
 	@Override
 	public boolean supportsKeyAgreement() {
 		return true;
@@ -200,7 +223,7 @@ class LanTcpPlugin extends TcpPlugin {
 
 	@Override
 	public DuplexTransportConnection createKeyAgreementConnection(
-			byte[] commitment, BdfList descriptor, long timeout) {
+			byte[] commitment, BdfList descriptor) {
 		if (!isRunning()) return null;
 		InetSocketAddress remote;
 		try {
@@ -218,10 +241,11 @@ class LanTcpPlugin extends TcpPlugin {
 			}
 			return null;
 		}
-		Socket s = new Socket();
 		try {
 			if (LOG.isLoggable(INFO))
 				LOG.info("Connecting to " + scrubSocketAddress(remote));
+			Socket s = createSocket();
+			s.bind(new InetSocketAddress(socket.getInetAddress(), 0));
 			s.connect(remote);
 			s.setSoTimeout(socketTimeout);
 			if (LOG.isLoggable(INFO))
@@ -259,14 +283,11 @@ class LanTcpPlugin extends TcpPlugin {
 		}
 
 		@Override
-		public Callable<KeyAgreementConnection> listen() {
-			return () -> {
-				Socket s = ss.accept();
-				if (LOG.isLoggable(INFO))
-					LOG.info(ID.getString() + ": Incoming connection");
-				return new KeyAgreementConnection(
-						new TcpTransportConnection(LanTcpPlugin.this, s), ID);
-			};
+		public KeyAgreementConnection accept() throws IOException {
+			Socket s = ss.accept();
+			if (LOG.isLoggable(INFO)) LOG.info(ID + ": Incoming connection");
+			return new KeyAgreementConnection(new TcpTransportConnection(
+					LanTcpPlugin.this, s), ID);
 		}
 
 		@Override
@@ -278,4 +299,19 @@ class LanTcpPlugin extends TcpPlugin {
 			}
 		}
 	}
+
+	static class LanAddressComparator implements Comparator<InetSocketAddress> {
+
+		@Override
+		public int compare(InetSocketAddress a, InetSocketAddress b) {
+			// Prefer addresses with non-zero ports
+			int aPort = a.getPort(), bPort = b.getPort();
+			if (aPort > 0 && bPort == 0) return -1;
+			if (aPort == 0 && bPort > 0) return 1;
+			// Prefer addresses with longer RFC 1918 prefixes
+			int aPrefix = getRfc1918PrefixLength(a.getAddress());
+			int bPrefix = getRfc1918PrefixLength(b.getAddress());
+			return bPrefix - aPrefix;
+		}
+	}
 }

bramble-core/src/main/java/org/briarproject/bramble/plugin/tcp/TcpPlugin.java

@@ -1,5 +1,6 @@
 package org.briarproject.bramble.plugin.tcp;
 
+import org.briarproject.bramble.PoliteExecutor;
 import org.briarproject.bramble.api.contact.ContactId;
 import org.briarproject.bramble.api.data.BdfList;
 import org.briarproject.bramble.api.keyagreement.KeyAgreementListener;
@@ -47,7 +48,7 @@ abstract class TcpPlugin implements DuplexPlugin {
 	private static final Logger LOG =
 			Logger.getLogger(TcpPlugin.class.getName());
 
-	protected final Executor ioExecutor;
+	protected final Executor ioExecutor, bindExecutor;
 	protected final Backoff backoff;
 	protected final DuplexPluginCallback callback;
 	protected final int maxLatency, maxIdleTime, socketTimeout;
@@ -90,6 +91,8 @@ abstract class TcpPlugin implements DuplexPlugin {
 		if (maxIdleTime > Integer.MAX_VALUE / 2)
 			socketTimeout = Integer.MAX_VALUE;
 		else socketTimeout = maxIdleTime * 2;
+		// Don't execute more than one bind operation at a time
+		bindExecutor = new PoliteExecutor("TcpPlugin", ioExecutor, 1);
 	}
 
 	@Override
@@ -110,8 +113,9 @@ abstract class TcpPlugin implements DuplexPlugin {
 	}
 
 	protected void bind() {
-		ioExecutor.execute(() -> {
+		bindExecutor.execute(() -> {
 			if (!running) return;
+			if (socket != null && !socket.isClosed()) return;
 			ServerSocket ss = null;
 			for (InetSocketAddress addr : getLocalSocketAddresses()) {
 				try {
@@ -243,10 +247,11 @@ abstract class TcpPlugin implements DuplexPlugin {
 				}
 				continue;
 			}
-			Socket s = new Socket();
 			try {
 				if (LOG.isLoggable(INFO))
 					LOG.info("Connecting to " + scrubSocketAddress(remote));
+				Socket s = createSocket();
+				s.bind(new InetSocketAddress(socket.getInetAddress(), 0));
 				s.connect(remote);
 				s.setSoTimeout(socketTimeout);
 				if (LOG.isLoggable(INFO))
@@ -261,6 +266,10 @@ abstract class TcpPlugin implements DuplexPlugin {
 		return null;
 	}
 
+	protected Socket createSocket() throws IOException {
+		return new Socket();
+	}
+
 	@Nullable
 	InetSocketAddress parseSocketAddress(String ipPort) {
 		if (StringUtils.isNullOrEmpty(ipPort)) return null;
@@ -297,7 +306,7 @@ abstract class TcpPlugin implements DuplexPlugin {
 
 	@Override
 	public DuplexTransportConnection createKeyAgreementConnection(
-			byte[] commitment, BdfList descriptor, long timeout) {
+			byte[] commitment, BdfList descriptor) {
 		throw new UnsupportedOperationException();
 	}
 

bramble-core/src/main/java/org/briarproject/bramble/properties/TransportPropertyManagerImpl.java

@@ -63,6 +63,7 @@ class TransportPropertyManagerImpl implements TransportPropertyManager,
 
 	@Override
 	public void createLocalState(Transaction txn) throws DbException {
+		if (db.containsGroup(txn, localGroup.getId())) return;
 		db.addGroup(txn, localGroup);
 		// Ensure we've set things up for any pre-existing contacts
 		for (Contact c : db.getContacts(txn)) addingContact(txn, c);

bramble-core/src/main/java/org/briarproject/bramble/sync/DuplexOutgoingSession.java

@@ -10,7 +10,7 @@ import org.briarproject.bramble.api.event.Event;
 import org.briarproject.bramble.api.event.EventBus;
 import org.briarproject.bramble.api.event.EventListener;
 import org.briarproject.bramble.api.lifecycle.IoExecutor;
-import org.briarproject.bramble.api.lifecycle.event.ShutdownEvent;
+import org.briarproject.bramble.api.lifecycle.event.LifecycleEvent;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.sync.Ack;
 import org.briarproject.bramble.api.sync.Offer;
@@ -29,6 +29,8 @@ import java.util.Collection;
 import java.util.concurrent.BlockingQueue;
 import java.util.concurrent.Executor;
 import java.util.concurrent.LinkedBlockingQueue;
+import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.concurrent.atomic.AtomicLong;
 import java.util.logging.Logger;
 
 import javax.annotation.concurrent.ThreadSafe;
@@ -36,6 +38,7 @@ import javax.annotation.concurrent.ThreadSafe;
 import static java.util.concurrent.TimeUnit.MILLISECONDS;
 import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
+import static org.briarproject.bramble.api.lifecycle.LifecycleManager.LifecycleState.STOPPING;
 import static org.briarproject.bramble.api.sync.SyncConstants.MAX_MESSAGE_IDS;
 import static org.briarproject.bramble.api.sync.SyncConstants.MAX_RECORD_PAYLOAD_LENGTH;
 
@@ -49,12 +52,14 @@ import static org.briarproject.bramble.api.sync.SyncConstants.MAX_RECORD_PAYLOAD
 @NotNullByDefault
 class DuplexOutgoingSession implements SyncSession, EventListener {
 
-	// Check for retransmittable records once every 60 seconds
-	private static final int RETX_QUERY_INTERVAL = 60 * 1000;
 	private static final Logger LOG =
 			Logger.getLogger(DuplexOutgoingSession.class.getName());
 
-	private static final ThrowingRunnable<IOException> CLOSE = () -> {};
+	private static final ThrowingRunnable<IOException> CLOSE = () -> {
+	};
+	private static final ThrowingRunnable<IOException>
+			NEXT_SEND_TIME_DECREASED = () -> {
+	};
 
 	private final DatabaseComponent db;
 	private final Executor dbExecutor;
@@ -65,6 +70,13 @@ class DuplexOutgoingSession implements SyncSession, EventListener {
 	private final RecordWriter recordWriter;
 	private final BlockingQueue<ThrowingRunnable<IOException>> writerTasks;
 
+	private final AtomicBoolean generateAckQueued = new AtomicBoolean(false);
+	private final AtomicBoolean generateBatchQueued = new AtomicBoolean(false);
+	private final AtomicBoolean generateOfferQueued = new AtomicBoolean(false);
+	private final AtomicBoolean generateRequestQueued =
+			new AtomicBoolean(false);
+	private final AtomicLong nextSendTime = new AtomicLong(Long.MAX_VALUE);
+
 	private volatile boolean interrupted = false;
 
 	DuplexOutgoingSession(DatabaseComponent db, Executor dbExecutor,
@@ -87,21 +99,21 @@ class DuplexOutgoingSession implements SyncSession, EventListener {
 		eventBus.addListener(this);
 		try {
 			// Start a query for each type of record
-			dbExecutor.execute(new GenerateAck());
-			dbExecutor.execute(new GenerateBatch());
-			dbExecutor.execute(new GenerateOffer());
-			dbExecutor.execute(new GenerateRequest());
+			generateAck();
+			generateBatch();
+			generateOffer();
+			generateRequest();
 			long now = clock.currentTimeMillis();
 			long nextKeepalive = now + maxIdleTime;
-			long nextRetxQuery = now + RETX_QUERY_INTERVAL;
 			boolean dataToFlush = true;
 			// Write records until interrupted
 			try {
 				while (!interrupted) {
 					// Work out how long we should wait for a record
 					now = clock.currentTimeMillis();
-					long wait = Math.min(nextKeepalive, nextRetxQuery) - now;
-					if (wait < 0) wait = 0;
+					long keepaliveWait = Math.max(0, nextKeepalive - now);
+					long sendWait = Math.max(0, nextSendTime.get() - now);
+					long wait = Math.min(keepaliveWait, sendWait);
 					// Flush any unflushed data if we're going to wait
 					if (wait > 0 && dataToFlush && writerTasks.isEmpty()) {
 						recordWriter.flush();
@@ -113,20 +125,25 @@ class DuplexOutgoingSession implements SyncSession, EventListener {
 							MILLISECONDS);
 					if (task == null) {
 						now = clock.currentTimeMillis();
-						if (now >= nextRetxQuery) {
-							// Check for retransmittable records
-							dbExecutor.execute(new GenerateBatch());
-							dbExecutor.execute(new GenerateOffer());
-							nextRetxQuery = now + RETX_QUERY_INTERVAL;
+						if (now >= nextSendTime.get()) {
+							// Check for retransmittable messages
+							LOG.info("Checking for retransmittable messages");
+							setNextSendTime(Long.MAX_VALUE);
+							generateBatch();
+							generateOffer();
 						}
 						if (now >= nextKeepalive) {
 							// Flush the stream to keep it alive
+							LOG.info("Sending keepalive");
 							recordWriter.flush();
 							dataToFlush = false;
 							nextKeepalive = now + maxIdleTime;
 						}
 					} else if (task == CLOSE) {
+						LOG.info("Closed");
 						break;
+					} else if (task == NEXT_SEND_TIME_DECREASED) {
+						LOG.info("Next send time decreased");
 					} else {
 						task.run();
 						dataToFlush = true;
@@ -142,6 +159,31 @@ class DuplexOutgoingSession implements SyncSession, EventListener {
 		}
 	}
 
+	private void generateAck() {
+		if (generateAckQueued.compareAndSet(false, true))
+			dbExecutor.execute(new GenerateAck());
+	}
+
+	private void generateBatch() {
+		if (generateBatchQueued.compareAndSet(false, true))
+			dbExecutor.execute(new GenerateBatch());
+	}
+
+	private void generateOffer() {
+		if (generateOfferQueued.compareAndSet(false, true))
+			dbExecutor.execute(new GenerateOffer());
+	}
+
+	private void generateRequest() {
+		if (generateRequestQueued.compareAndSet(false, true))
+			dbExecutor.execute(new GenerateRequest());
+	}
+
+	private void setNextSendTime(long time) {
+		long old = nextSendTime.getAndSet(time);
+		if (time < old) writerTasks.add(NEXT_SEND_TIME_DECREASED);
+	}
+
 	@Override
 	public void interrupt() {
 		interrupted = true;
@@ -154,22 +196,23 @@ class DuplexOutgoingSession implements SyncSession, EventListener {
 			ContactRemovedEvent c = (ContactRemovedEvent) e;
 			if (c.getContactId().equals(contactId)) interrupt();
 		} else if (e instanceof MessageSharedEvent) {
-			dbExecutor.execute(new GenerateOffer());
+			generateOffer();
 		} else if (e instanceof GroupVisibilityUpdatedEvent) {
 			GroupVisibilityUpdatedEvent g = (GroupVisibilityUpdatedEvent) e;
 			if (g.getAffectedContacts().contains(contactId))
-				dbExecutor.execute(new GenerateOffer());
+				generateOffer();
 		} else if (e instanceof MessageRequestedEvent) {
 			if (((MessageRequestedEvent) e).getContactId().equals(contactId))
-				dbExecutor.execute(new GenerateBatch());
+				generateBatch();
 		} else if (e instanceof MessageToAckEvent) {
 			if (((MessageToAckEvent) e).getContactId().equals(contactId))
-				dbExecutor.execute(new GenerateAck());
+				generateAck();
 		} else if (e instanceof MessageToRequestEvent) {
 			if (((MessageToRequestEvent) e).getContactId().equals(contactId))
-				dbExecutor.execute(new GenerateRequest());
-		} else if (e instanceof ShutdownEvent) {
-			interrupt();
+				generateRequest();
+		} else if (e instanceof LifecycleEvent) {
+			LifecycleEvent l = (LifecycleEvent) e;
+			if (l.getLifecycleState() == STOPPING) interrupt();
 		}
 	}
 
@@ -179,6 +222,7 @@ class DuplexOutgoingSession implements SyncSession, EventListener {
 		@Override
 		public void run() {
 			if (interrupted) return;
+			if (!generateAckQueued.getAndSet(false)) throw new AssertionError();
 			try {
 				Ack a;
 				Transaction txn = db.startTransaction(false);
@@ -212,7 +256,7 @@ class DuplexOutgoingSession implements SyncSession, EventListener {
 			if (interrupted) return;
 			recordWriter.writeAck(ack);
 			LOG.info("Sent ack");
-			dbExecutor.execute(new GenerateAck());
+			generateAck();
 		}
 	}
 
@@ -222,12 +266,15 @@ class DuplexOutgoingSession implements SyncSession, EventListener {
 		@Override
 		public void run() {
 			if (interrupted) return;
+			if (!generateBatchQueued.getAndSet(false))
+				throw new AssertionError();
 			try {
 				Collection<byte[]> b;
 				Transaction txn = db.startTransaction(false);
 				try {
 					b = db.generateRequestedBatch(txn, contactId,
 							MAX_RECORD_PAYLOAD_LENGTH, maxLatency);
+					setNextSendTime(db.getNextSendTime(txn, contactId));
 					db.commitTransaction(txn);
 				} finally {
 					db.endTransaction(txn);
@@ -256,7 +303,7 @@ class DuplexOutgoingSession implements SyncSession, EventListener {
 			if (interrupted) return;
 			for (byte[] raw : batch) recordWriter.writeMessage(raw);
 			LOG.info("Sent batch");
-			dbExecutor.execute(new GenerateBatch());
+			generateBatch();
 		}
 	}
 
@@ -266,12 +313,15 @@ class DuplexOutgoingSession implements SyncSession, EventListener {
 		@Override
 		public void run() {
 			if (interrupted) return;
+			if (!generateOfferQueued.getAndSet(false))
+				throw new AssertionError();
 			try {
 				Offer o;
 				Transaction txn = db.startTransaction(false);
 				try {
 					o = db.generateOffer(txn, contactId, MAX_MESSAGE_IDS,
 							maxLatency);
+					setNextSendTime(db.getNextSendTime(txn, contactId));
 					db.commitTransaction(txn);
 				} finally {
 					db.endTransaction(txn);
@@ -300,7 +350,7 @@ class DuplexOutgoingSession implements SyncSession, EventListener {
 			if (interrupted) return;
 			recordWriter.writeOffer(offer);
 			LOG.info("Sent offer");
-			dbExecutor.execute(new GenerateOffer());
+			generateOffer();
 		}
 	}
 
@@ -310,6 +360,8 @@ class DuplexOutgoingSession implements SyncSession, EventListener {
 		@Override
 		public void run() {
 			if (interrupted) return;
+			if (!generateRequestQueued.getAndSet(false))
+				throw new AssertionError();
 			try {
 				Request r;
 				Transaction txn = db.startTransaction(false);
@@ -343,7 +395,7 @@ class DuplexOutgoingSession implements SyncSession, EventListener {
 			if (interrupted) return;
 			recordWriter.writeRequest(request);
 			LOG.info("Sent request");
-			dbExecutor.execute(new GenerateRequest());
+			generateRequest();
 		}
 	}
 }

bramble-core/src/main/java/org/briarproject/bramble/sync/IncomingSession.java

@@ -11,7 +11,7 @@ import org.briarproject.bramble.api.event.Event;
 import org.briarproject.bramble.api.event.EventBus;
 import org.briarproject.bramble.api.event.EventListener;
 import org.briarproject.bramble.api.lifecycle.IoExecutor;
-import org.briarproject.bramble.api.lifecycle.event.ShutdownEvent;
+import org.briarproject.bramble.api.lifecycle.event.LifecycleEvent;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.sync.Ack;
 import org.briarproject.bramble.api.sync.Message;
@@ -27,6 +27,7 @@ import java.util.logging.Logger;
 import javax.annotation.concurrent.ThreadSafe;
 
 import static java.util.logging.Level.WARNING;
+import static org.briarproject.bramble.api.lifecycle.LifecycleManager.LifecycleState.STOPPING;
 
 /**
  * An incoming {@link SyncSession}.
@@ -96,8 +97,9 @@ class IncomingSession implements SyncSession, EventListener {
 		if (e instanceof ContactRemovedEvent) {
 			ContactRemovedEvent c = (ContactRemovedEvent) e;
 			if (c.getContactId().equals(contactId)) interrupt();
-		} else if (e instanceof ShutdownEvent) {
-			interrupt();
+		} else if (e instanceof LifecycleEvent) {
+			LifecycleEvent l = (LifecycleEvent) e;
+			if (l.getLifecycleState() == STOPPING) interrupt();
 		}
 	}
 

bramble-core/src/main/java/org/briarproject/bramble/sync/SimplexOutgoingSession.java

@@ -10,7 +10,7 @@ import org.briarproject.bramble.api.event.Event;
 import org.briarproject.bramble.api.event.EventBus;
 import org.briarproject.bramble.api.event.EventListener;
 import org.briarproject.bramble.api.lifecycle.IoExecutor;
-import org.briarproject.bramble.api.lifecycle.event.ShutdownEvent;
+import org.briarproject.bramble.api.lifecycle.event.LifecycleEvent;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.sync.Ack;
 import org.briarproject.bramble.api.sync.RecordWriter;
@@ -28,6 +28,7 @@ import javax.annotation.concurrent.ThreadSafe;
 
 import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
+import static org.briarproject.bramble.api.lifecycle.LifecycleManager.LifecycleState.STOPPING;
 import static org.briarproject.bramble.api.sync.SyncConstants.MAX_MESSAGE_IDS;
 import static org.briarproject.bramble.api.sync.SyncConstants.MAX_RECORD_PAYLOAD_LENGTH;
 
@@ -109,8 +110,9 @@ class SimplexOutgoingSession implements SyncSession, EventListener {
 		if (e instanceof ContactRemovedEvent) {
 			ContactRemovedEvent c = (ContactRemovedEvent) e;
 			if (c.getContactId().equals(contactId)) interrupt();
-		} else if (e instanceof ShutdownEvent) {
-			interrupt();
+		} else if (e instanceof LifecycleEvent) {
+			LifecycleEvent l = (LifecycleEvent) e;
+			if (l.getLifecycleState() == STOPPING) interrupt();
 		}
 	}
 

bramble-core/src/main/java/org/briarproject/bramble/sync/ValidationManagerImpl.java

@@ -71,11 +71,9 @@ class ValidationManagerImpl implements ValidationManager, Service,
 	@Override
 	public void startService() {
 		if (used.getAndSet(true)) throw new IllegalStateException();
-		for (ClientId c : validators.keySet()) {
-			validateOutstandingMessagesAsync(c);
-			deliverOutstandingMessagesAsync(c);
-			shareOutstandingMessagesAsync(c);
-		}
+		validateOutstandingMessagesAsync();
+		deliverOutstandingMessagesAsync();
+		shareOutstandingMessagesAsync();
 	}
 
 	@Override
@@ -93,17 +91,17 @@ class ValidationManagerImpl implements ValidationManager, Service,
 		hooks.put(c, hook);
 	}
 
-	private void validateOutstandingMessagesAsync(ClientId c) {
-		dbExecutor.execute(() -> validateOutstandingMessages(c));
+	private void validateOutstandingMessagesAsync() {
+		dbExecutor.execute(this::validateOutstandingMessages);
 	}
 
 	@DatabaseExecutor
-	private void validateOutstandingMessages(ClientId c) {
+	private void validateOutstandingMessages() {
 		try {
 			Queue<MessageId> unvalidated = new LinkedList<>();
 			Transaction txn = db.startTransaction(true);
 			try {
-				unvalidated.addAll(db.getMessagesToValidate(txn, c));
+				unvalidated.addAll(db.getMessagesToValidate(txn));
 				db.commitTransaction(txn);
 			} finally {
 				db.endTransaction(txn);
@@ -148,17 +146,17 @@ class ValidationManagerImpl implements ValidationManager, Service,
 		}
 	}
 
-	private void deliverOutstandingMessagesAsync(ClientId c) {
-		dbExecutor.execute(() -> deliverOutstandingMessages(c));
+	private void deliverOutstandingMessagesAsync() {
+		dbExecutor.execute(this::deliverOutstandingMessages);
 	}
 
 	@DatabaseExecutor
-	private void deliverOutstandingMessages(ClientId c) {
+	private void deliverOutstandingMessages() {
 		try {
 			Queue<MessageId> pending = new LinkedList<>();
 			Transaction txn = db.startTransaction(true);
 			try {
-				pending.addAll(db.getPendingMessages(txn, c));
+				pending.addAll(db.getPendingMessages(txn));
 				db.commitTransaction(txn);
 			} finally {
 				db.endTransaction(txn);
@@ -353,17 +351,17 @@ class ValidationManagerImpl implements ValidationManager, Service,
 		return pending;
 	}
 
-	private void shareOutstandingMessagesAsync(ClientId c) {
-		dbExecutor.execute(() -> shareOutstandingMessages(c));
+	private void shareOutstandingMessagesAsync() {
+		dbExecutor.execute(this::shareOutstandingMessages);
 	}
 
 	@DatabaseExecutor
-	private void shareOutstandingMessages(ClientId c) {
+	private void shareOutstandingMessages() {
 		try {
 			Queue<MessageId> toShare = new LinkedList<>();
 			Transaction txn = db.startTransaction(true);
 			try {
-				toShare.addAll(db.getMessagesToShare(txn, c));
+				toShare.addAll(db.getMessagesToShare(txn));
 				db.commitTransaction(txn);
 			} finally {
 				db.endTransaction(txn);

bramble-core/src/main/java/org/briarproject/bramble/system/SystemModule.java

@@ -4,8 +4,9 @@ import org.briarproject.bramble.api.lifecycle.LifecycleManager;
 import org.briarproject.bramble.api.system.Clock;
 import org.briarproject.bramble.api.system.Scheduler;
 
-import java.util.concurrent.Executors;
+import java.util.concurrent.RejectedExecutionHandler;
 import java.util.concurrent.ScheduledExecutorService;
+import java.util.concurrent.ScheduledThreadPoolExecutor;
 
 import javax.inject.Inject;
 import javax.inject.Singleton;
@@ -25,7 +26,10 @@ public class SystemModule {
 	private final ScheduledExecutorService scheduler;
 
 	public SystemModule() {
-		scheduler = Executors.newSingleThreadScheduledExecutor();
+		// Discard tasks that are submitted during shutdown
+		RejectedExecutionHandler policy =
+				new ScheduledThreadPoolExecutor.DiscardPolicy();
+		scheduler = new ScheduledThreadPoolExecutor(1, policy);
 	}
 
 	@Provides

bramble-core/src/test/java/org/briarproject/bramble/db/DatabaseComponentImplTest.java

@@ -47,19 +47,22 @@ import org.briarproject.bramble.api.sync.event.MessagesSentEvent;
 import org.briarproject.bramble.api.transport.IncomingKeys;
 import org.briarproject.bramble.api.transport.OutgoingKeys;
 import org.briarproject.bramble.api.transport.TransportKeys;
-import org.briarproject.bramble.test.BrambleTestCase;
+import org.briarproject.bramble.test.BrambleMockTestCase;
+import org.briarproject.bramble.test.CaptureArgumentAction;
 import org.briarproject.bramble.test.TestUtils;
 import org.briarproject.bramble.util.StringUtils;
 import org.jmock.Expectations;
-import org.jmock.Mockery;
 import org.junit.Test;
 
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
-import java.util.Collections;
 import java.util.Map;
+import java.util.concurrent.atomic.AtomicReference;
 
+import static java.util.Collections.emptyMap;
+import static java.util.Collections.singletonList;
+import static java.util.Collections.singletonMap;
 import static org.briarproject.bramble.api.identity.AuthorConstants.MAX_PUBLIC_KEY_LENGTH;
 import static org.briarproject.bramble.api.sync.Group.Visibility.INVISIBLE;
 import static org.briarproject.bramble.api.sync.Group.Visibility.SHARED;
@@ -74,7 +77,13 @@ import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.fail;
 
-public class DatabaseComponentImplTest extends BrambleTestCase {
+public class DatabaseComponentImplTest extends BrambleMockTestCase {
+
+	@SuppressWarnings("unchecked")
+	private final Database<Object> database = context.mock(Database.class);
+	private final ShutdownManager shutdown =
+			context.mock(ShutdownManager.class);
+	private final EventBus eventBus = context.mock(EventBus.class);
 
 	private final Object txn = new Object();
 	private final ClientId clientId;
@@ -125,16 +134,11 @@ public class DatabaseComponentImplTest extends BrambleTestCase {
 	}
 
 	@Test
-	@SuppressWarnings("unchecked")
 	public void testSimpleCalls() throws Exception {
 		int shutdownHandle = 12345;
-		Mockery context = new Mockery();
-		Database<Object> database = context.mock(Database.class);
-		ShutdownManager shutdown = context.mock(ShutdownManager.class);
-		EventBus eventBus = context.mock(EventBus.class);
 		context.checking(new Expectations() {{
 			// open()
-			oneOf(database).open();
+			oneOf(database).open(null);
 			will(returnValue(false));
 			oneOf(shutdown).addShutdownHook(with(any(Runnable.class)));
 			will(returnValue(shutdownHandle));
@@ -160,7 +164,7 @@ public class DatabaseComponentImplTest extends BrambleTestCase {
 					ContactStatusChangedEvent.class)));
 			// getContacts()
 			oneOf(database).getContacts(txn);
-			will(returnValue(Collections.singletonList(contact)));
+			will(returnValue(singletonList(contact)));
 			// addGroup()
 			oneOf(database).containsGroup(txn, groupId);
 			will(returnValue(false));
@@ -171,12 +175,12 @@ public class DatabaseComponentImplTest extends BrambleTestCase {
 			will(returnValue(true));
 			// getGroups()
 			oneOf(database).getGroups(txn, clientId);
-			will(returnValue(Collections.singletonList(group)));
+			will(returnValue(singletonList(group)));
 			// removeGroup()
 			oneOf(database).containsGroup(txn, groupId);
 			will(returnValue(true));
 			oneOf(database).getGroupVisibility(txn, groupId);
-			will(returnValue(Collections.emptyList()));
+			will(returnValue(emptyMap()));
 			oneOf(database).removeGroup(txn, groupId);
 			oneOf(eventBus).broadcast(with(any(GroupRemovedEvent.class)));
 			oneOf(eventBus).broadcast(with(any(
@@ -194,24 +198,23 @@ public class DatabaseComponentImplTest extends BrambleTestCase {
 			// endTransaction()
 			oneOf(database).commitTransaction(txn);
 			// close()
-			oneOf(shutdown).removeShutdownHook(shutdownHandle);
 			oneOf(database).close();
 		}});
 		DatabaseComponent db = createDatabaseComponent(database, eventBus,
 				shutdown);
 
-		assertFalse(db.open());
+		assertFalse(db.open(null));
 		Transaction transaction = db.startTransaction(false);
 		try {
 			db.addLocalAuthor(transaction, localAuthor);
 			assertEquals(contactId,
 					db.addContact(transaction, author, localAuthorId, true,
 							true));
-			assertEquals(Collections.singletonList(contact),
+			assertEquals(singletonList(contact),
 					db.getContacts(transaction));
 			db.addGroup(transaction, group); // First time - listeners called
 			db.addGroup(transaction, group); // Second time - not called
-			assertEquals(Collections.singletonList(group),
+			assertEquals(singletonList(group),
 					db.getGroups(transaction, clientId));
 			db.removeGroup(transaction, group);
 			db.removeContact(transaction, contactId);
@@ -221,18 +224,11 @@ public class DatabaseComponentImplTest extends BrambleTestCase {
 			db.endTransaction(transaction);
 		}
 		db.close();
-
-		context.assertIsSatisfied();
 	}
 
 	@Test
 	public void testLocalMessagesAreNotStoredUnlessGroupExists()
 			throws Exception {
-		Mockery context = new Mockery();
-		@SuppressWarnings("unchecked")
-		Database<Object> database = context.mock(Database.class);
-		ShutdownManager shutdown = context.mock(ShutdownManager.class);
-		EventBus eventBus = context.mock(EventBus.class);
 		context.checking(new Expectations() {{
 			oneOf(database).startTransaction();
 			will(returnValue(txn));
@@ -252,17 +248,10 @@ public class DatabaseComponentImplTest extends BrambleTestCase {
 		} finally {
 			db.endTransaction(transaction);
 		}
-
-		context.assertIsSatisfied();
 	}
 
 	@Test
 	public void testAddLocalMessage() throws Exception {
-		Mockery context = new Mockery();
-		@SuppressWarnings("unchecked")
-		Database<Object> database = context.mock(Database.class);
-		ShutdownManager shutdown = context.mock(ShutdownManager.class);
-		EventBus eventBus = context.mock(EventBus.class);
 		context.checking(new Expectations() {{
 			oneOf(database).startTransaction();
 			will(returnValue(txn));
@@ -270,13 +259,8 @@ public class DatabaseComponentImplTest extends BrambleTestCase {
 			will(returnValue(true));
 			oneOf(database).containsMessage(txn, messageId);
 			will(returnValue(false));
-			oneOf(database).addMessage(txn, message, DELIVERED, true);
+			oneOf(database).addMessage(txn, message, DELIVERED, true, null);
 			oneOf(database).mergeMessageMetadata(txn, messageId, metadata);
-			oneOf(database).getGroupVisibility(txn, groupId);
-			will(returnValue(Collections.singletonList(contactId)));
-			oneOf(database).removeOfferedMessage(txn, contactId, messageId);
-			will(returnValue(false));
-			oneOf(database).addStatus(txn, contactId, messageId, false, false);
 			oneOf(database).commitTransaction(txn);
 			// The message was added, so the listeners should be called
 			oneOf(eventBus).broadcast(with(any(MessageAddedEvent.class)));
@@ -294,18 +278,11 @@ public class DatabaseComponentImplTest extends BrambleTestCase {
 		} finally {
 			db.endTransaction(transaction);
 		}
-
-		context.assertIsSatisfied();
 	}
 
 	@Test
 	public void testVariousMethodsThrowExceptionIfContactIsMissing()
 			throws Exception {
-		Mockery context = new Mockery();
-		@SuppressWarnings("unchecked")
-		Database<Object> database = context.mock(Database.class);
-		ShutdownManager shutdown = context.mock(ShutdownManager.class);
-		EventBus eventBus = context.mock(EventBus.class);
 		context.checking(new Expectations() {{
 			// Check whether the contact is in the DB (which it's not)
 			exactly(18).of(database).startTransaction();
@@ -419,7 +396,7 @@ public class DatabaseComponentImplTest extends BrambleTestCase {
 
 		transaction = db.startTransaction(false);
 		try {
-			Ack a = new Ack(Collections.singletonList(messageId));
+			Ack a = new Ack(singletonList(messageId));
 			db.receiveAck(transaction, contactId, a);
 			fail();
 		} catch (NoSuchContactException expected) {
@@ -440,7 +417,7 @@ public class DatabaseComponentImplTest extends BrambleTestCase {
 
 		transaction = db.startTransaction(false);
 		try {
-			Offer o = new Offer(Collections.singletonList(messageId));
+			Offer o = new Offer(singletonList(messageId));
 			db.receiveOffer(transaction, contactId, o);
 			fail();
 		} catch (NoSuchContactException expected) {
@@ -451,7 +428,7 @@ public class DatabaseComponentImplTest extends BrambleTestCase {
 
 		transaction = db.startTransaction(false);
 		try {
-			Request r = new Request(Collections.singletonList(messageId));
+			Request r = new Request(singletonList(messageId));
 			db.receiveRequest(transaction, contactId, r);
 			fail();
 		} catch (NoSuchContactException expected) {
@@ -500,18 +477,11 @@ public class DatabaseComponentImplTest extends BrambleTestCase {
 		} finally {
 			db.endTransaction(transaction);
 		}
-
-		context.assertIsSatisfied();
 	}
 
 	@Test
 	public void testVariousMethodsThrowExceptionIfLocalAuthorIsMissing()
 			throws Exception {
-		Mockery context = new Mockery();
-		@SuppressWarnings("unchecked")
-		Database<Object> database = context.mock(Database.class);
-		ShutdownManager shutdown = context.mock(ShutdownManager.class);
-		EventBus eventBus = context.mock(EventBus.class);
 		context.checking(new Expectations() {{
 			// Check whether the pseudonym is in the DB (which it's not)
 			exactly(3).of(database).startTransaction();
@@ -552,18 +522,11 @@ public class DatabaseComponentImplTest extends BrambleTestCase {
 		} finally {
 			db.endTransaction(transaction);
 		}
-
-		context.assertIsSatisfied();
 	}
 
 	@Test
 	public void testVariousMethodsThrowExceptionIfGroupIsMissing()
 			throws Exception {
-		Mockery context = new Mockery();
-		@SuppressWarnings("unchecked")
-		Database<Object> database = context.mock(Database.class);
-		ShutdownManager shutdown = context.mock(ShutdownManager.class);
-		EventBus eventBus = context.mock(EventBus.class);
 		context.checking(new Expectations() {{
 			// Check whether the group is in the DB (which it's not)
 			exactly(8).of(database).startTransaction();
@@ -657,18 +620,11 @@ public class DatabaseComponentImplTest extends BrambleTestCase {
 		} finally {
 			db.endTransaction(transaction);
 		}
-
-		context.assertIsSatisfied();
 	}
 
 	@Test
 	public void testVariousMethodsThrowExceptionIfMessageIsMissing()
 			throws Exception {
-		Mockery context = new Mockery();
-		@SuppressWarnings("unchecked")
-		Database<Object> database = context.mock(Database.class);
-		ShutdownManager shutdown = context.mock(ShutdownManager.class);
-		EventBus eventBus = context.mock(EventBus.class);
 		context.checking(new Expectations() {{
 			// Check whether the message is in the DB (which it's not)
 			exactly(11).of(database).startTransaction();
@@ -792,18 +748,11 @@ public class DatabaseComponentImplTest extends BrambleTestCase {
 		} finally {
 			db.endTransaction(transaction);
 		}
-
-		context.assertIsSatisfied();
 	}
 
 	@Test
 	public void testVariousMethodsThrowExceptionIfTransportIsMissing()
 			throws Exception {
-		Mockery context = new Mockery();
-		@SuppressWarnings("unchecked")
-		Database<Object> database = context.mock(Database.class);
-		ShutdownManager shutdown = context.mock(ShutdownManager.class);
-		EventBus eventBus = context.mock(EventBus.class);
 		context.checking(new Expectations() {{
 			// startTransaction()
 			oneOf(database).startTransaction();
@@ -890,19 +839,12 @@ public class DatabaseComponentImplTest extends BrambleTestCase {
 		} finally {
 			db.endTransaction(transaction);
 		}
-
-		context.assertIsSatisfied();
 	}
 
 	@Test
 	public void testGenerateAck() throws Exception {
 		Collection<MessageId> messagesToAck = Arrays.asList(messageId,
 				messageId1);
-		Mockery context = new Mockery();
-		@SuppressWarnings("unchecked")
-		Database<Object> database = context.mock(Database.class);
-		ShutdownManager shutdown = context.mock(ShutdownManager.class);
-		EventBus eventBus = context.mock(EventBus.class);
 		context.checking(new Expectations() {{
 			oneOf(database).startTransaction();
 			will(returnValue(txn));
@@ -925,8 +867,6 @@ public class DatabaseComponentImplTest extends BrambleTestCase {
 		} finally {
 			db.endTransaction(transaction);
 		}
-
-		context.assertIsSatisfied();
 	}
 
 	@Test
@@ -934,11 +874,6 @@ public class DatabaseComponentImplTest extends BrambleTestCase {
 		byte[] raw1 = new byte[size];
 		Collection<MessageId> ids = Arrays.asList(messageId, messageId1);
 		Collection<byte[]> messages = Arrays.asList(raw, raw1);
-		Mockery context = new Mockery();
-		@SuppressWarnings("unchecked")
-		Database<Object> database = context.mock(Database.class);
-		ShutdownManager shutdown = context.mock(ShutdownManager.class);
-		EventBus eventBus = context.mock(EventBus.class);
 		context.checking(new Expectations() {{
 			oneOf(database).startTransaction();
 			will(returnValue(txn));
@@ -969,19 +904,12 @@ public class DatabaseComponentImplTest extends BrambleTestCase {
 		} finally {
 			db.endTransaction(transaction);
 		}
-
-		context.assertIsSatisfied();
 	}
 
 	@Test
 	public void testGenerateOffer() throws Exception {
 		MessageId messageId1 = new MessageId(TestUtils.getRandomId());
 		Collection<MessageId> ids = Arrays.asList(messageId, messageId1);
-		Mockery context = new Mockery();
-		@SuppressWarnings("unchecked")
-		Database<Object> database = context.mock(Database.class);
-		ShutdownManager shutdown = context.mock(ShutdownManager.class);
-		EventBus eventBus = context.mock(EventBus.class);
 		context.checking(new Expectations() {{
 			oneOf(database).startTransaction();
 			will(returnValue(txn));
@@ -1007,19 +935,12 @@ public class DatabaseComponentImplTest extends BrambleTestCase {
 		} finally {
 			db.endTransaction(transaction);
 		}
-
-		context.assertIsSatisfied();
 	}
 
 	@Test
 	public void testGenerateRequest() throws Exception {
 		MessageId messageId1 = new MessageId(TestUtils.getRandomId());
 		Collection<MessageId> ids = Arrays.asList(messageId, messageId1);
-		Mockery context = new Mockery();
-		@SuppressWarnings("unchecked")
-		Database<Object> database = context.mock(Database.class);
-		ShutdownManager shutdown = context.mock(ShutdownManager.class);
-		EventBus eventBus = context.mock(EventBus.class);
 		context.checking(new Expectations() {{
 			oneOf(database).startTransaction();
 			will(returnValue(txn));
@@ -1042,8 +963,6 @@ public class DatabaseComponentImplTest extends BrambleTestCase {
 		} finally {
 			db.endTransaction(transaction);
 		}
-
-		context.assertIsSatisfied();
 	}
 
 	@Test
@@ -1051,11 +970,6 @@ public class DatabaseComponentImplTest extends BrambleTestCase {
 		byte[] raw1 = new byte[size];
 		Collection<MessageId> ids = Arrays.asList(messageId, messageId1);
 		Collection<byte[]> messages = Arrays.asList(raw, raw1);
-		Mockery context = new Mockery();
-		@SuppressWarnings("unchecked")
-		Database<Object> database = context.mock(Database.class);
-		ShutdownManager shutdown = context.mock(ShutdownManager.class);
-		EventBus eventBus = context.mock(EventBus.class);
 		context.checking(new Expectations() {{
 			oneOf(database).startTransaction();
 			will(returnValue(txn));
@@ -1087,17 +1001,10 @@ public class DatabaseComponentImplTest extends BrambleTestCase {
 		} finally {
 			db.endTransaction(transaction);
 		}
-
-		context.assertIsSatisfied();
 	}
 
 	@Test
 	public void testReceiveAck() throws Exception {
-		Mockery context = new Mockery();
-		@SuppressWarnings("unchecked")
-		Database<Object> database = context.mock(Database.class);
-		ShutdownManager shutdown = context.mock(ShutdownManager.class);
-		EventBus eventBus = context.mock(EventBus.class);
 		context.checking(new Expectations() {{
 			oneOf(database).startTransaction();
 			will(returnValue(txn));
@@ -1114,23 +1021,16 @@ public class DatabaseComponentImplTest extends BrambleTestCase {
 
 		Transaction transaction = db.startTransaction(false);
 		try {
-			Ack a = new Ack(Collections.singletonList(messageId));
+			Ack a = new Ack(singletonList(messageId));
 			db.receiveAck(transaction, contactId, a);
 			db.commitTransaction(transaction);
 		} finally {
 			db.endTransaction(transaction);
 		}
-
-		context.assertIsSatisfied();
 	}
 
 	@Test
 	public void testReceiveMessage() throws Exception {
-		Mockery context = new Mockery();
-		@SuppressWarnings("unchecked")
-		Database<Object> database = context.mock(Database.class);
-		ShutdownManager shutdown = context.mock(ShutdownManager.class);
-		EventBus eventBus = context.mock(EventBus.class);
 		context.checking(new Expectations() {{
 			oneOf(database).startTransaction();
 			will(returnValue(txn));
@@ -1141,12 +1041,7 @@ public class DatabaseComponentImplTest extends BrambleTestCase {
 			will(returnValue(VISIBLE));
 			oneOf(database).containsMessage(txn, messageId);
 			will(returnValue(false));
-			oneOf(database).addMessage(txn, message, UNKNOWN, false);
-			oneOf(database).getGroupVisibility(txn, groupId);
-			will(returnValue(Collections.singletonList(contactId)));
-			oneOf(database).removeOfferedMessage(txn, contactId, messageId);
-			will(returnValue(false));
-			oneOf(database).addStatus(txn, contactId, messageId, true, true);
+			oneOf(database).addMessage(txn, message, UNKNOWN, false, contactId);
 			// Second time
 			oneOf(database).containsContact(txn, contactId);
 			will(returnValue(true));
@@ -1175,17 +1070,10 @@ public class DatabaseComponentImplTest extends BrambleTestCase {
 		} finally {
 			db.endTransaction(transaction);
 		}
-
-		context.assertIsSatisfied();
 	}
 
 	@Test
 	public void testReceiveDuplicateMessage() throws Exception {
-		Mockery context = new Mockery();
-		@SuppressWarnings("unchecked")
-		Database<Object> database = context.mock(Database.class);
-		ShutdownManager shutdown = context.mock(ShutdownManager.class);
-		EventBus eventBus = context.mock(EventBus.class);
 		context.checking(new Expectations() {{
 			oneOf(database).startTransaction();
 			will(returnValue(txn));
@@ -1212,17 +1100,10 @@ public class DatabaseComponentImplTest extends BrambleTestCase {
 		} finally {
 			db.endTransaction(transaction);
 		}
-
-		context.assertIsSatisfied();
 	}
 
 	@Test
 	public void testReceiveMessageWithoutVisibleGroup() throws Exception {
-		Mockery context = new Mockery();
-		@SuppressWarnings("unchecked")
-		Database<Object> database = context.mock(Database.class);
-		ShutdownManager shutdown = context.mock(ShutdownManager.class);
-		EventBus eventBus = context.mock(EventBus.class);
 		context.checking(new Expectations() {{
 			oneOf(database).startTransaction();
 			will(returnValue(txn));
@@ -1242,8 +1123,6 @@ public class DatabaseComponentImplTest extends BrambleTestCase {
 		} finally {
 			db.endTransaction(transaction);
 		}
-
-		context.assertIsSatisfied();
 	}
 
 	@Test
@@ -1251,11 +1130,6 @@ public class DatabaseComponentImplTest extends BrambleTestCase {
 		MessageId messageId1 = new MessageId(TestUtils.getRandomId());
 		MessageId messageId2 = new MessageId(TestUtils.getRandomId());
 		MessageId messageId3 = new MessageId(TestUtils.getRandomId());
-		Mockery context = new Mockery();
-		@SuppressWarnings("unchecked")
-		Database<Object> database = context.mock(Database.class);
-		ShutdownManager shutdown = context.mock(ShutdownManager.class);
-		EventBus eventBus = context.mock(EventBus.class);
 		context.checking(new Expectations() {{
 			oneOf(database).startTransaction();
 			will(returnValue(txn));
@@ -1296,17 +1170,10 @@ public class DatabaseComponentImplTest extends BrambleTestCase {
 		} finally {
 			db.endTransaction(transaction);
 		}
-
-		context.assertIsSatisfied();
 	}
 
 	@Test
 	public void testReceiveRequest() throws Exception {
-		Mockery context = new Mockery();
-		@SuppressWarnings("unchecked")
-		Database<Object> database = context.mock(Database.class);
-		ShutdownManager shutdown = context.mock(ShutdownManager.class);
-		EventBus eventBus = context.mock(EventBus.class);
 		context.checking(new Expectations() {{
 			oneOf(database).startTransaction();
 			will(returnValue(txn));
@@ -1324,23 +1191,20 @@ public class DatabaseComponentImplTest extends BrambleTestCase {
 
 		Transaction transaction = db.startTransaction(false);
 		try {
-			Request r = new Request(Collections.singletonList(messageId));
+			Request r = new Request(singletonList(messageId));
 			db.receiveRequest(transaction, contactId, r);
 			db.commitTransaction(transaction);
 		} finally {
 			db.endTransaction(transaction);
 		}
-
-		context.assertIsSatisfied();
 	}
 
 	@Test
-	public void testChangingVisibilityCallsListeners() throws Exception {
-		Mockery context = new Mockery();
-		@SuppressWarnings("unchecked")
-		Database<Object> database = context.mock(Database.class);
-		ShutdownManager shutdown = context.mock(ShutdownManager.class);
-		EventBus eventBus = context.mock(EventBus.class);
+	public void testChangingVisibilityFromInvisibleToVisibleCallsListeners()
+			throws Exception {
+		AtomicReference<GroupVisibilityUpdatedEvent> event =
+				new AtomicReference<>();
+
 		context.checking(new Expectations() {{
 			oneOf(database).startTransaction();
 			will(returnValue(txn));
@@ -1349,16 +1213,13 @@ public class DatabaseComponentImplTest extends BrambleTestCase {
 			oneOf(database).containsGroup(txn, groupId);
 			will(returnValue(true));
 			oneOf(database).getGroupVisibility(txn, contactId, groupId);
-			will(returnValue(INVISIBLE)); // Not yet visible
+			will(returnValue(INVISIBLE));
 			oneOf(database).addGroupVisibility(txn, contactId, groupId, false);
-			oneOf(database).getMessageIds(txn, groupId);
-			will(returnValue(Collections.singletonList(messageId)));
-			oneOf(database).removeOfferedMessage(txn, contactId, messageId);
-			will(returnValue(false));
-			oneOf(database).addStatus(txn, contactId, messageId, false, false);
 			oneOf(database).commitTransaction(txn);
 			oneOf(eventBus).broadcast(with(any(
 					GroupVisibilityUpdatedEvent.class)));
+			will(new CaptureArgumentAction<>(event,
+					GroupVisibilityUpdatedEvent.class, 0));
 		}});
 		DatabaseComponent db = createDatabaseComponent(database, eventBus,
 				shutdown);
@@ -1371,17 +1232,52 @@ public class DatabaseComponentImplTest extends BrambleTestCase {
 			db.endTransaction(transaction);
 		}
 
-		context.assertIsSatisfied();
+		GroupVisibilityUpdatedEvent e = event.get();
+		assertNotNull(e);
+		assertEquals(singletonList(contactId), e.getAffectedContacts());
+	}
+
+	@Test
+	public void testChangingVisibilityFromVisibleToInvisibleCallsListeners()
+			throws Exception {
+		AtomicReference<GroupVisibilityUpdatedEvent> event =
+				new AtomicReference<>();
+
+		context.checking(new Expectations() {{
+			oneOf(database).startTransaction();
+			will(returnValue(txn));
+			oneOf(database).containsContact(txn, contactId);
+			will(returnValue(true));
+			oneOf(database).containsGroup(txn, groupId);
+			will(returnValue(true));
+			oneOf(database).getGroupVisibility(txn, contactId, groupId);
+			will(returnValue(VISIBLE));
+			oneOf(database).removeGroupVisibility(txn, contactId, groupId);
+			oneOf(database).commitTransaction(txn);
+			oneOf(eventBus).broadcast(with(any(
+					GroupVisibilityUpdatedEvent.class)));
+			will(new CaptureArgumentAction<>(event,
+					GroupVisibilityUpdatedEvent.class, 0));
+		}});
+		DatabaseComponent db = createDatabaseComponent(database, eventBus,
+				shutdown);
+
+		Transaction transaction = db.startTransaction(false);
+		try {
+			db.setGroupVisibility(transaction, contactId, groupId, INVISIBLE);
+			db.commitTransaction(transaction);
+		} finally {
+			db.endTransaction(transaction);
+		}
+
+		GroupVisibilityUpdatedEvent e = event.get();
+		assertNotNull(e);
+		assertEquals(singletonList(contactId), e.getAffectedContacts());
 	}
 
 	@Test
 	public void testNotChangingVisibilityDoesNotCallListeners()
 			throws Exception {
-		Mockery context = new Mockery();
-		@SuppressWarnings("unchecked")
-		Database<Object> database = context.mock(Database.class);
-		ShutdownManager shutdown = context.mock(ShutdownManager.class);
-		EventBus eventBus = context.mock(EventBus.class);
 		context.checking(new Expectations() {{
 			oneOf(database).startTransaction();
 			will(returnValue(txn));
@@ -1403,20 +1299,13 @@ public class DatabaseComponentImplTest extends BrambleTestCase {
 		} finally {
 			db.endTransaction(transaction);
 		}
-
-		context.assertIsSatisfied();
 	}
 
 	@Test
 	public void testTransportKeys() throws Exception {
 		TransportKeys transportKeys = createTransportKeys();
-		Map<ContactId, TransportKeys> keys = Collections.singletonMap(
-				contactId, transportKeys);
-		Mockery context = new Mockery();
-		@SuppressWarnings("unchecked")
-		Database<Object> database = context.mock(Database.class);
-		ShutdownManager shutdown = context.mock(ShutdownManager.class);
-		EventBus eventBus = context.mock(EventBus.class);
+		Map<ContactId, TransportKeys> keys =
+				singletonMap(contactId, transportKeys);
 		context.checking(new Expectations() {{
 			// startTransaction()
 			oneOf(database).startTransaction();
@@ -1446,8 +1335,6 @@ public class DatabaseComponentImplTest extends BrambleTestCase {
 		} finally {
 			db.endTransaction(transaction);
 		}
-
-		context.assertIsSatisfied();
 	}
 
 	private TransportKeys createTransportKeys() {
@@ -1480,11 +1367,6 @@ public class DatabaseComponentImplTest extends BrambleTestCase {
 		Settings merged = new Settings();
 		merged.put("foo", "bar");
 		merged.put("baz", "qux");
-		Mockery context = new Mockery();
-		@SuppressWarnings("unchecked")
-		Database<Object> database = context.mock(Database.class);
-		ShutdownManager shutdown = context.mock(ShutdownManager.class);
-		EventBus eventBus = context.mock(EventBus.class);
 		context.checking(new Expectations() {{
 			// startTransaction()
 			oneOf(database).startTransaction();
@@ -1514,8 +1396,6 @@ public class DatabaseComponentImplTest extends BrambleTestCase {
 		} finally {
 			db.endTransaction(transaction);
 		}
-
-		context.assertIsSatisfied();
 	}
 
 	@Test(expected = IllegalStateException.class)
@@ -1545,12 +1425,6 @@ public class DatabaseComponentImplTest extends BrambleTestCase {
 	private void testCannotStartTransactionDuringTransaction(
 			boolean firstTxnReadOnly, boolean secondTxnReadOnly)
 			throws Exception {
-		Mockery context = new Mockery();
-		@SuppressWarnings("unchecked")
-		Database<Object> database = context.mock(Database.class);
-		ShutdownManager shutdown = context.mock(ShutdownManager.class);
-		EventBus eventBus = context.mock(EventBus.class);
-
 		context.checking(new Expectations() {{
 			oneOf(database).startTransaction();
 			will(returnValue(txn));
@@ -1560,22 +1434,12 @@ public class DatabaseComponentImplTest extends BrambleTestCase {
 				shutdown);
 
 		assertNotNull(db.startTransaction(firstTxnReadOnly));
-		try {
-			db.startTransaction(secondTxnReadOnly);
-			fail();
-		} finally {
-			context.assertIsSatisfied();
-		}
+		db.startTransaction(secondTxnReadOnly);
+		fail();
 	}
 
 	@Test
 	public void testCannotAddLocalIdentityAsContact() throws Exception {
-		Mockery context = new Mockery();
-		@SuppressWarnings("unchecked")
-		Database<Object> database = context.mock(Database.class);
-		ShutdownManager shutdown = context.mock(ShutdownManager.class);
-		EventBus eventBus = context.mock(EventBus.class);
-
 		context.checking(new Expectations() {{
 			oneOf(database).startTransaction();
 			will(returnValue(txn));
@@ -1599,18 +1463,10 @@ public class DatabaseComponentImplTest extends BrambleTestCase {
 		} finally {
 			db.endTransaction(transaction);
 		}
-
-		context.assertIsSatisfied();
 	}
 
 	@Test
 	public void testCannotAddDuplicateContact() throws Exception {
-		Mockery context = new Mockery();
-		@SuppressWarnings("unchecked")
-		Database<Object> database = context.mock(Database.class);
-		ShutdownManager shutdown = context.mock(ShutdownManager.class);
-		EventBus eventBus = context.mock(EventBus.class);
-
 		context.checking(new Expectations() {{
 			oneOf(database).startTransaction();
 			will(returnValue(txn));
@@ -1636,22 +1492,16 @@ public class DatabaseComponentImplTest extends BrambleTestCase {
 		} finally {
 			db.endTransaction(transaction);
 		}
-
-		context.assertIsSatisfied();
 	}
 
 	@Test
 	@SuppressWarnings("unchecked")
 	public void testMessageDependencies() throws Exception {
 		int shutdownHandle = 12345;
-		Mockery context = new Mockery();
-		Database<Object> database = context.mock(Database.class);
-		ShutdownManager shutdown = context.mock(ShutdownManager.class);
-		EventBus eventBus = context.mock(EventBus.class);
 		MessageId messageId2 = new MessageId(TestUtils.getRandomId());
 		context.checking(new Expectations() {{
 			// open()
-			oneOf(database).open();
+			oneOf(database).open(null);
 			will(returnValue(false));
 			oneOf(shutdown).addShutdownHook(with(any(Runnable.class)));
 			will(returnValue(shutdownHandle));
@@ -1663,13 +1513,8 @@ public class DatabaseComponentImplTest extends BrambleTestCase {
 			will(returnValue(true));
 			oneOf(database).containsMessage(txn, messageId);
 			will(returnValue(false));
-			oneOf(database).addMessage(txn, message, DELIVERED, true);
-			oneOf(database).getGroupVisibility(txn, groupId);
-			will(returnValue(Collections.singletonList(contactId)));
+			oneOf(database).addMessage(txn, message, DELIVERED, true, null);
 			oneOf(database).mergeMessageMetadata(txn, messageId, metadata);
-			oneOf(database).removeOfferedMessage(txn, contactId, messageId);
-			will(returnValue(false));
-			oneOf(database).addStatus(txn, contactId, messageId, false, false);
 			// addMessageDependencies()
 			oneOf(database).containsMessage(txn, messageId);
 			will(returnValue(true));
@@ -1693,13 +1538,12 @@ public class DatabaseComponentImplTest extends BrambleTestCase {
 			// endTransaction()
 			oneOf(database).commitTransaction(txn);
 			// close()
-			oneOf(shutdown).removeShutdownHook(shutdownHandle);
 			oneOf(database).close();
 		}});
 		DatabaseComponent db = createDatabaseComponent(database, eventBus,
 				shutdown);
 
-		assertFalse(db.open());
+		assertFalse(db.open(null));
 		Transaction transaction = db.startTransaction(false);
 		try {
 			db.addLocalMessage(transaction, message, metadata, true);
@@ -1714,7 +1558,5 @@ public class DatabaseComponentImplTest extends BrambleTestCase {
 			db.endTransaction(transaction);
 		}
 		db.close();
-
-		context.assertIsSatisfied();
 	}
 }

bramble-core/src/test/java/org/briarproject/bramble/db/DatabaseMigrationTest.java

@@ -0,0 +1,233 @@
+package org.briarproject.bramble.db;
+
+import org.briarproject.bramble.api.db.DataTooNewException;
+import org.briarproject.bramble.api.db.DataTooOldException;
+import org.briarproject.bramble.api.db.DatabaseConfig;
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.settings.Settings;
+import org.briarproject.bramble.api.system.Clock;
+import org.briarproject.bramble.system.SystemClock;
+import org.briarproject.bramble.test.BrambleMockTestCase;
+import org.briarproject.bramble.test.TestDatabaseConfig;
+import org.briarproject.bramble.test.TestUtils;
+import org.jmock.Expectations;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+
+import java.io.File;
+import java.sql.Connection;
+import java.util.List;
+
+import static java.util.Arrays.asList;
+import static java.util.Collections.emptyList;
+import static java.util.Collections.singletonList;
+import static org.briarproject.bramble.db.DatabaseConstants.DB_SETTINGS_NAMESPACE;
+import static org.briarproject.bramble.db.DatabaseConstants.SCHEMA_VERSION_KEY;
+import static org.briarproject.bramble.db.JdbcDatabase.CODE_SCHEMA_VERSION;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+@NotNullByDefault
+public abstract class DatabaseMigrationTest extends BrambleMockTestCase {
+
+	private final File testDir = TestUtils.getTestDirectory();
+	@SuppressWarnings("unchecked")
+	private final Migration<Connection> migration =
+			context.mock(Migration.class, "migration");
+	@SuppressWarnings("unchecked")
+	private final Migration<Connection> migration1 =
+			context.mock(Migration.class, "migration1");
+
+	protected final DatabaseConfig config =
+			new TestDatabaseConfig(testDir, 1024 * 1024);
+	protected final Clock clock = new SystemClock();
+
+	abstract Database<Connection> createDatabase(
+			List<Migration<Connection>> migrations) throws Exception;
+
+	@Before
+	public void setUp() {
+		assertTrue(testDir.mkdirs());
+	}
+
+	@After
+	public void tearDown() {
+		TestUtils.deleteTestDirectory(testDir);
+	}
+
+	@Test
+	public void testDoesNotRunMigrationsWhenCreatingDatabase()
+			throws Exception {
+		Database<Connection> db = createDatabase(singletonList(migration));
+		assertFalse(db.open(null));
+		assertEquals(CODE_SCHEMA_VERSION, getDataSchemaVersion(db));
+		db.close();
+	}
+
+	@Test(expected = DbException.class)
+	public void testThrowsExceptionIfDataSchemaVersionIsMissing()
+			throws Exception {
+		// Open the DB for the first time
+		Database<Connection> db = createDatabase(asList(migration, migration1));
+		assertFalse(db.open(null));
+		assertEquals(CODE_SCHEMA_VERSION, getDataSchemaVersion(db));
+		// Override the data schema version
+		setDataSchemaVersion(db, -1);
+		db.close();
+		// Reopen the DB - an exception should be thrown
+		db = createDatabase(asList(migration, migration1));
+		db.open(null);
+	}
+
+	@Test
+	public void testDoesNotRunMigrationsIfSchemaVersionsMatch()
+			throws Exception {
+		// Open the DB for the first time
+		Database<Connection> db = createDatabase(asList(migration, migration1));
+		assertFalse(db.open(null));
+		assertEquals(CODE_SCHEMA_VERSION, getDataSchemaVersion(db));
+		db.close();
+		// Reopen the DB - migrations should not be run
+		db = createDatabase(asList(migration, migration1));
+		assertTrue(db.open(null));
+		assertEquals(CODE_SCHEMA_VERSION, getDataSchemaVersion(db));
+		db.close();
+	}
+
+	@Test(expected = DataTooNewException.class)
+	public void testThrowsExceptionIfDataIsNewerThanCode() throws Exception {
+		// Open the DB for the first time
+		Database<Connection> db = createDatabase(asList(migration, migration1));
+		assertFalse(db.open(null));
+		assertEquals(CODE_SCHEMA_VERSION, getDataSchemaVersion(db));
+		// Override the data schema version
+		setDataSchemaVersion(db, CODE_SCHEMA_VERSION + 1);
+		db.close();
+		// Reopen the DB - an exception should be thrown
+		db = createDatabase(asList(migration, migration1));
+		db.open(null);
+	}
+
+	@Test(expected = DataTooOldException.class)
+	public void testThrowsExceptionIfCodeIsNewerThanDataAndNoMigrations()
+			throws Exception {
+		// Open the DB for the first time
+		Database<Connection> db = createDatabase(emptyList());
+		assertFalse(db.open(null));
+		assertEquals(CODE_SCHEMA_VERSION, getDataSchemaVersion(db));
+		setDataSchemaVersion(db, CODE_SCHEMA_VERSION - 1);
+		db.close();
+		// Reopen the DB - an exception should be thrown
+		db = createDatabase(emptyList());
+		db.open(null);
+	}
+
+	@Test(expected = DataTooOldException.class)
+	public void testThrowsExceptionIfCodeIsNewerThanDataAndNoSuitableMigration()
+			throws Exception {
+		context.checking(new Expectations() {{
+			oneOf(migration).getStartVersion();
+			will(returnValue(CODE_SCHEMA_VERSION - 2));
+			oneOf(migration).getEndVersion();
+			will(returnValue(CODE_SCHEMA_VERSION - 1));
+			oneOf(migration1).getStartVersion();
+			will(returnValue(CODE_SCHEMA_VERSION - 1));
+			oneOf(migration1).getEndVersion();
+			will(returnValue(CODE_SCHEMA_VERSION));
+		}});
+
+		// Open the DB for the first time
+		Database<Connection> db = createDatabase(asList(migration, migration1));
+		assertFalse(db.open(null));
+		assertEquals(CODE_SCHEMA_VERSION, getDataSchemaVersion(db));
+		// Override the data schema version
+		setDataSchemaVersion(db, CODE_SCHEMA_VERSION - 3);
+		db.close();
+		// Reopen the DB - an exception should be thrown
+		db = createDatabase(asList(migration, migration1));
+		db.open(null);
+	}
+
+	@Test
+	public void testRunsMigrationIfCodeIsNewerThanDataAndSuitableMigration()
+			throws Exception {
+		context.checking(new Expectations() {{
+			// First migration should be run, increasing schema version by 2
+			oneOf(migration).getStartVersion();
+			will(returnValue(CODE_SCHEMA_VERSION - 2));
+			oneOf(migration).getEndVersion();
+			will(returnValue(CODE_SCHEMA_VERSION));
+			oneOf(migration).migrate(with(any(Connection.class)));
+			// Second migration is not suitable and should be skipped
+			oneOf(migration1).getStartVersion();
+			will(returnValue(CODE_SCHEMA_VERSION - 1));
+			oneOf(migration1).getEndVersion();
+			will(returnValue(CODE_SCHEMA_VERSION));
+		}});
+
+		// Open the DB for the first time
+		Database<Connection> db = createDatabase(asList(migration, migration1));
+		assertFalse(db.open(null));
+		assertEquals(CODE_SCHEMA_VERSION, getDataSchemaVersion(db));
+		// Override the data schema version
+		setDataSchemaVersion(db, CODE_SCHEMA_VERSION - 2);
+		db.close();
+		// Reopen the DB - the first migration should be run
+		db = createDatabase(asList(migration, migration1));
+		assertTrue(db.open(null));
+		assertEquals(CODE_SCHEMA_VERSION, getDataSchemaVersion(db));
+		db.close();
+	}
+
+	@Test
+	public void testRunsMigrationsIfCodeIsNewerThanDataAndSuitableMigrations()
+			throws Exception {
+		context.checking(new Expectations() {{
+			// First migration should be run, incrementing schema version
+			oneOf(migration).getStartVersion();
+			will(returnValue(CODE_SCHEMA_VERSION - 2));
+			oneOf(migration).getEndVersion();
+			will(returnValue(CODE_SCHEMA_VERSION - 1));
+			oneOf(migration).migrate(with(any(Connection.class)));
+			// Second migration should be run, incrementing schema version again
+			oneOf(migration1).getStartVersion();
+			will(returnValue(CODE_SCHEMA_VERSION - 1));
+			oneOf(migration1).getEndVersion();
+			will(returnValue(CODE_SCHEMA_VERSION));
+			oneOf(migration1).migrate(with(any(Connection.class)));
+		}});
+
+		// Open the DB for the first time
+		Database<Connection> db = createDatabase(asList(migration, migration1));
+		assertFalse(db.open(null));
+		assertEquals(CODE_SCHEMA_VERSION, getDataSchemaVersion(db));
+		// Override the data schema version
+		setDataSchemaVersion(db, CODE_SCHEMA_VERSION - 2);
+		db.close();
+		// Reopen the DB - both migrations should be run
+		db = createDatabase(asList(migration, migration1));
+		assertTrue(db.open(null));
+		assertEquals(CODE_SCHEMA_VERSION, getDataSchemaVersion(db));
+		db.close();
+	}
+
+	private int getDataSchemaVersion(Database<Connection> db)
+			throws Exception {
+		Connection txn = db.startTransaction();
+		Settings s = db.getSettings(txn, DB_SETTINGS_NAMESPACE);
+		db.commitTransaction(txn);
+		return s.getInt(SCHEMA_VERSION_KEY, -1);
+	}
+
+	private void setDataSchemaVersion(Database<Connection> db, int version)
+			throws Exception {
+		Settings s = new Settings();
+		s.putInt(SCHEMA_VERSION_KEY, version);
+		Connection txn = db.startTransaction();
+		db.mergeSettings(txn, s, DB_SETTINGS_NAMESPACE);
+		db.commitTransaction(txn);
+	}
+}

bramble-core/src/test/java/org/briarproject/bramble/db/H2DatabaseTest.java

@@ -6,7 +6,6 @@ import org.briarproject.bramble.api.crypto.SecretKey;
 import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.db.Metadata;
 import org.briarproject.bramble.api.identity.Author;
-import org.briarproject.bramble.api.identity.AuthorId;
 import org.briarproject.bramble.api.identity.LocalAuthor;
 import org.briarproject.bramble.api.plugin.TransportId;
 import org.briarproject.bramble.api.settings.Settings;
@@ -17,6 +16,7 @@ import org.briarproject.bramble.api.sync.Message;
 import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.bramble.api.sync.MessageStatus;
 import org.briarproject.bramble.api.sync.ValidationManager.State;
+import org.briarproject.bramble.api.system.Clock;
 import org.briarproject.bramble.api.transport.IncomingKeys;
 import org.briarproject.bramble.api.transport.OutgoingKeys;
 import org.briarproject.bramble.api.transport.TransportKeys;
@@ -24,7 +24,6 @@ import org.briarproject.bramble.system.SystemClock;
 import org.briarproject.bramble.test.BrambleTestCase;
 import org.briarproject.bramble.test.TestDatabaseConfig;
 import org.briarproject.bramble.test.TestUtils;
-import org.briarproject.bramble.util.StringUtils;
 import org.junit.After;
 import org.junit.Before;
 import org.junit.Test;
@@ -44,7 +43,6 @@ import java.util.concurrent.atomic.AtomicBoolean;
 
 import static java.util.concurrent.TimeUnit.SECONDS;
 import static org.briarproject.bramble.api.db.Metadata.REMOVE;
-import static org.briarproject.bramble.api.identity.AuthorConstants.MAX_PUBLIC_KEY_LENGTH;
 import static org.briarproject.bramble.api.sync.Group.Visibility.INVISIBLE;
 import static org.briarproject.bramble.api.sync.Group.Visibility.SHARED;
 import static org.briarproject.bramble.api.sync.Group.Visibility.VISIBLE;
@@ -54,6 +52,12 @@ import static org.briarproject.bramble.api.sync.ValidationManager.State.DELIVERE
 import static org.briarproject.bramble.api.sync.ValidationManager.State.INVALID;
 import static org.briarproject.bramble.api.sync.ValidationManager.State.PENDING;
 import static org.briarproject.bramble.api.sync.ValidationManager.State.UNKNOWN;
+import static org.briarproject.bramble.test.TestUtils.getAuthor;
+import static org.briarproject.bramble.test.TestUtils.getLocalAuthor;
+import static org.briarproject.bramble.test.TestUtils.getRandomBytes;
+import static org.briarproject.bramble.test.TestUtils.getRandomId;
+import static org.briarproject.bramble.test.TestUtils.getSecretKey;
+import static org.briarproject.bramble.util.StringUtils.getRandomString;
 import static org.junit.Assert.assertArrayEquals;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
@@ -73,7 +77,6 @@ public class H2DatabaseTest extends BrambleTestCase {
 	private final ClientId clientId;
 	private final Group group;
 	private final Author author;
-	private final AuthorId localAuthorId;
 	private final LocalAuthor localAuthor;
 	private final MessageId messageId;
 	private final long timestamp;
@@ -84,19 +87,16 @@ public class H2DatabaseTest extends BrambleTestCase {
 	private final ContactId contactId;
 
 	public H2DatabaseTest() throws Exception {
-		groupId = new GroupId(TestUtils.getRandomId());
-		clientId = new ClientId(StringUtils.getRandomString(5));
+		groupId = new GroupId(getRandomId());
+		clientId = new ClientId(getRandomString(123));
 		byte[] descriptor = new byte[MAX_GROUP_DESCRIPTOR_LENGTH];
 		group = new Group(groupId, clientId, descriptor);
-		AuthorId authorId = new AuthorId(TestUtils.getRandomId());
-		author = new Author(authorId, "Alice", new byte[MAX_PUBLIC_KEY_LENGTH]);
-		localAuthorId = new AuthorId(TestUtils.getRandomId());
+		author = getAuthor();
+		localAuthor = getLocalAuthor();
+		messageId = new MessageId(getRandomId());
 		timestamp = System.currentTimeMillis();
-		localAuthor = new LocalAuthor(localAuthorId, "Bob",
-				new byte[MAX_PUBLIC_KEY_LENGTH], new byte[123], timestamp);
-		messageId = new MessageId(TestUtils.getRandomId());
 		size = 1234;
-		raw = TestUtils.getRandomBytes(size);
+		raw = getRandomBytes(size);
 		message = new Message(messageId, groupId, timestamp, raw);
 		transportId = new TransportId("id");
 		contactId = new ContactId(1);
@@ -114,14 +114,14 @@ public class H2DatabaseTest extends BrambleTestCase {
 		Connection txn = db.startTransaction();
 		assertFalse(db.containsContact(txn, contactId));
 		db.addLocalAuthor(txn, localAuthor);
-		assertEquals(contactId, db.addContact(txn, author, localAuthorId,
+		assertEquals(contactId, db.addContact(txn, author, localAuthor.getId(),
 				true, true));
 		assertTrue(db.containsContact(txn, contactId));
 		assertFalse(db.containsGroup(txn, groupId));
 		db.addGroup(txn, group);
 		assertTrue(db.containsGroup(txn, groupId));
 		assertFalse(db.containsMessage(txn, messageId));
-		db.addMessage(txn, message, DELIVERED, true);
+		db.addMessage(txn, message, DELIVERED, true, null);
 		assertTrue(db.containsMessage(txn, messageId));
 		db.commitTransaction(txn);
 		db.close();
@@ -159,7 +159,7 @@ public class H2DatabaseTest extends BrambleTestCase {
 
 		// Add a group and a message
 		db.addGroup(txn, group);
-		db.addMessage(txn, message, DELIVERED, true);
+		db.addMessage(txn, message, DELIVERED, true, null);
 
 		// Removing the group should remove the message
 		assertTrue(db.containsMessage(txn, messageId));
@@ -177,22 +177,15 @@ public class H2DatabaseTest extends BrambleTestCase {
 
 		// Add a contact, a shared group and a shared message
 		db.addLocalAuthor(txn, localAuthor);
-		assertEquals(contactId, db.addContact(txn, author, localAuthorId,
+		assertEquals(contactId, db.addContact(txn, author, localAuthor.getId(),
 				true, true));
 		db.addGroup(txn, group);
 		db.addGroupVisibility(txn, contactId, groupId, true);
-		db.addMessage(txn, message, DELIVERED, true);
+		db.addMessage(txn, message, DELIVERED, true, null);
 
-		// The message has no status yet, so it should not be sendable
-		Collection<MessageId> ids = db.getMessagesToSend(txn, contactId,
-				ONE_MEGABYTE);
-		assertTrue(ids.isEmpty());
-		ids = db.getMessagesToOffer(txn, contactId, 100);
-		assertTrue(ids.isEmpty());
-
-		// Adding a status with seen = false should make the message sendable
-		db.addStatus(txn, contactId, messageId, false, false);
-		ids = db.getMessagesToSend(txn, contactId, ONE_MEGABYTE);
+		// The contact has not seen the message, so it should be sendable
+		Collection<MessageId> ids =
+				db.getMessagesToSend(txn, contactId, ONE_MEGABYTE);
 		assertEquals(Collections.singletonList(messageId), ids);
 		ids = db.getMessagesToOffer(txn, contactId, 100);
 		assertEquals(Collections.singletonList(messageId), ids);
@@ -215,12 +208,11 @@ public class H2DatabaseTest extends BrambleTestCase {
 
 		// Add a contact, a shared group and a shared but unvalidated message
 		db.addLocalAuthor(txn, localAuthor);
-		assertEquals(contactId, db.addContact(txn, author, localAuthorId,
+		assertEquals(contactId, db.addContact(txn, author, localAuthor.getId(),
 				true, true));
 		db.addGroup(txn, group);
 		db.addGroupVisibility(txn, contactId, groupId, true);
-		db.addMessage(txn, message, UNKNOWN, true);
-		db.addStatus(txn, contactId, messageId, false, false);
+		db.addMessage(txn, message, UNKNOWN, true, null);
 
 		// The message has not been validated, so it should not be sendable
 		Collection<MessageId> ids = db.getMessagesToSend(txn, contactId,
@@ -261,11 +253,10 @@ public class H2DatabaseTest extends BrambleTestCase {
 
 		// Add a contact, an invisible group and a shared message
 		db.addLocalAuthor(txn, localAuthor);
-		assertEquals(contactId, db.addContact(txn, author, localAuthorId,
+		assertEquals(contactId, db.addContact(txn, author, localAuthor.getId(),
 				true, true));
 		db.addGroup(txn, group);
-		db.addMessage(txn, message, DELIVERED, true);
-		db.addStatus(txn, contactId, messageId, false, false);
+		db.addMessage(txn, message, DELIVERED, true, null);
 
 		// The group is invisible, so the message should not be sendable
 		Collection<MessageId> ids = db.getMessagesToSend(txn, contactId,
@@ -313,12 +304,11 @@ public class H2DatabaseTest extends BrambleTestCase {
 
 		// Add a contact, a shared group and an unshared message
 		db.addLocalAuthor(txn, localAuthor);
-		assertEquals(contactId, db.addContact(txn, author, localAuthorId,
+		assertEquals(contactId, db.addContact(txn, author, localAuthor.getId(),
 				true, true));
 		db.addGroup(txn, group);
 		db.addGroupVisibility(txn, contactId, groupId, true);
-		db.addMessage(txn, message, DELIVERED, false);
-		db.addStatus(txn, contactId, messageId, false, false);
+		db.addMessage(txn, message, DELIVERED, false, null);
 
 		// The message is not shared, so it should not be sendable
 		Collection<MessageId> ids = db.getMessagesToSend(txn, contactId,
@@ -345,12 +335,11 @@ public class H2DatabaseTest extends BrambleTestCase {
 
 		// Add a contact, a shared group and a shared message
 		db.addLocalAuthor(txn, localAuthor);
-		assertEquals(contactId, db.addContact(txn, author, localAuthorId,
+		assertEquals(contactId, db.addContact(txn, author, localAuthor.getId(),
 				true, true));
 		db.addGroup(txn, group);
 		db.addGroupVisibility(txn, contactId, groupId, true);
-		db.addMessage(txn, message, DELIVERED, true);
-		db.addStatus(txn, contactId, messageId, false, false);
+		db.addMessage(txn, message, DELIVERED, true, null);
 
 		// The message is sendable, but too large to send
 		Collection<MessageId> ids = db.getMessagesToSend(txn, contactId,
@@ -372,20 +361,16 @@ public class H2DatabaseTest extends BrambleTestCase {
 
 		// Add a contact and a visible group
 		db.addLocalAuthor(txn, localAuthor);
-		assertEquals(contactId, db.addContact(txn, author, localAuthorId,
+		assertEquals(contactId, db.addContact(txn, author, localAuthor.getId(),
 				true, true));
 		db.addGroup(txn, group);
 		db.addGroupVisibility(txn, contactId, groupId, false);
 
 		// Add some messages to ack
-		MessageId messageId1 = new MessageId(TestUtils.getRandomId());
+		MessageId messageId1 = new MessageId(getRandomId());
 		Message message1 = new Message(messageId1, groupId, timestamp, raw);
-		db.addMessage(txn, message, DELIVERED, true);
-		db.addStatus(txn, contactId, messageId, false, true);
-		db.raiseAckFlag(txn, contactId, messageId);
-		db.addMessage(txn, message1, DELIVERED, true);
-		db.addStatus(txn, contactId, messageId1, false, true);
-		db.raiseAckFlag(txn, contactId, messageId1);
+		db.addMessage(txn, message, DELIVERED, true, contactId);
+		db.addMessage(txn, message1, DELIVERED, true, contactId);
 
 		// Both message IDs should be returned
 		Collection<MessageId> ids = db.getMessagesToAck(txn, contactId, 1234);
@@ -398,6 +383,14 @@ public class H2DatabaseTest extends BrambleTestCase {
 		assertEquals(Collections.emptyList(), db.getMessagesToAck(txn,
 				contactId, 1234));
 
+		// Raise the ack flag again
+		db.raiseAckFlag(txn, contactId, messageId);
+		db.raiseAckFlag(txn, contactId, messageId1);
+
+		// Both message IDs should be returned
+		ids = db.getMessagesToAck(txn, contactId, 1234);
+		assertEquals(Arrays.asList(messageId, messageId1), ids);
+
 		db.commitTransaction(txn);
 		db.close();
 	}
@@ -409,12 +402,11 @@ public class H2DatabaseTest extends BrambleTestCase {
 
 		// Add a contact, a shared group and a shared message
 		db.addLocalAuthor(txn, localAuthor);
-		assertEquals(contactId, db.addContact(txn, author, localAuthorId,
+		assertEquals(contactId, db.addContact(txn, author, localAuthor.getId(),
 				true, true));
 		db.addGroup(txn, group);
 		db.addGroupVisibility(txn, contactId, groupId, true);
-		db.addMessage(txn, message, DELIVERED, true);
-		db.addStatus(txn, contactId, messageId, false, false);
+		db.addMessage(txn, message, DELIVERED, true, null);
 
 		// Retrieve the message from the database and mark it as sent
 		Collection<MessageId> ids = db.getMessagesToSend(txn, contactId,
@@ -455,7 +447,7 @@ public class H2DatabaseTest extends BrambleTestCase {
 		// Storing a message should reduce the free space
 		Connection txn = db.startTransaction();
 		db.addGroup(txn, group);
-		db.addMessage(txn, message, DELIVERED, true);
+		db.addMessage(txn, message, DELIVERED, true, null);
 		db.commitTransaction(txn);
 		assertTrue(db.getFreeSpace() < free);
 
@@ -567,7 +559,7 @@ public class H2DatabaseTest extends BrambleTestCase {
 
 		// Add a contact and a shared group
 		db.addLocalAuthor(txn, localAuthor);
-		assertEquals(contactId, db.addContact(txn, author, localAuthorId,
+		assertEquals(contactId, db.addContact(txn, author, localAuthor.getId(),
 				true, true));
 		db.addGroup(txn, group);
 		db.addGroupVisibility(txn, contactId, groupId, true);
@@ -587,7 +579,7 @@ public class H2DatabaseTest extends BrambleTestCase {
 
 		// Add a contact
 		db.addLocalAuthor(txn, localAuthor);
-		assertEquals(contactId, db.addContact(txn, author, localAuthorId,
+		assertEquals(contactId, db.addContact(txn, author, localAuthor.getId(),
 				true, true));
 
 		// The group is not in the database
@@ -603,15 +595,14 @@ public class H2DatabaseTest extends BrambleTestCase {
 		Database<Connection> db = open(false);
 		Connection txn = db.startTransaction();
 
-		// Add a contact, a group and a message
+		// Add a contact, an invisible group and a message
 		db.addLocalAuthor(txn, localAuthor);
-		assertEquals(contactId, db.addContact(txn, author, localAuthorId,
+		assertEquals(contactId, db.addContact(txn, author, localAuthor.getId(),
 				true, true));
 		db.addGroup(txn, group);
-		db.addMessage(txn, message, DELIVERED, true);
-		db.addStatus(txn, contactId, messageId, false, false);
+		db.addMessage(txn, message, DELIVERED, true, null);
 
-		// The group is not visible
+		// The group is not visible so the message should not be visible
 		assertFalse(db.containsVisibleMessage(txn, contactId, messageId));
 
 		db.commitTransaction(txn);
@@ -625,37 +616,37 @@ public class H2DatabaseTest extends BrambleTestCase {
 
 		// Add a contact and a group
 		db.addLocalAuthor(txn, localAuthor);
-		assertEquals(contactId, db.addContact(txn, author, localAuthorId,
+		assertEquals(contactId, db.addContact(txn, author, localAuthor.getId(),
 				true, true));
 		db.addGroup(txn, group);
 
 		// The group should not be visible to the contact
 		assertEquals(INVISIBLE, db.getGroupVisibility(txn, contactId, groupId));
-		assertEquals(Collections.emptyList(),
+		assertEquals(Collections.emptyMap(),
 				db.getGroupVisibility(txn, groupId));
 
 		// Make the group visible to the contact
 		db.addGroupVisibility(txn, contactId, groupId, false);
 		assertEquals(VISIBLE, db.getGroupVisibility(txn, contactId, groupId));
-		assertEquals(Collections.singletonList(contactId),
+		assertEquals(Collections.singletonMap(contactId, false),
 				db.getGroupVisibility(txn, groupId));
 
 		// Share the group with the contact
 		db.setGroupVisibility(txn, contactId, groupId, true);
 		assertEquals(SHARED, db.getGroupVisibility(txn, contactId, groupId));
-		assertEquals(Collections.singletonList(contactId),
+		assertEquals(Collections.singletonMap(contactId, true),
 				db.getGroupVisibility(txn, groupId));
 
 		// Unshare the group with the contact
 		db.setGroupVisibility(txn, contactId, groupId, false);
 		assertEquals(VISIBLE, db.getGroupVisibility(txn, contactId, groupId));
-		assertEquals(Collections.singletonList(contactId),
+		assertEquals(Collections.singletonMap(contactId, false),
 				db.getGroupVisibility(txn, groupId));
 
 		// Make the group invisible again
 		db.removeGroupVisibility(txn, contactId, groupId);
 		assertEquals(INVISIBLE, db.getGroupVisibility(txn, contactId, groupId));
-		assertEquals(Collections.emptyList(),
+		assertEquals(Collections.emptyMap(),
 				db.getGroupVisibility(txn, groupId));
 
 		db.commitTransaction(txn);
@@ -675,7 +666,7 @@ public class H2DatabaseTest extends BrambleTestCase {
 
 		// Add the contact, the transport and the transport keys
 		db.addLocalAuthor(txn, localAuthor);
-		assertEquals(contactId, db.addContact(txn, author, localAuthorId,
+		assertEquals(contactId, db.addContact(txn, author, localAuthor.getId(),
 				true, true));
 		db.addTransport(txn, transportId, 123);
 		db.addTransportKeys(txn, contactId, keys);
@@ -737,7 +728,7 @@ public class H2DatabaseTest extends BrambleTestCase {
 
 		// Add the contact, transport and transport keys
 		db.addLocalAuthor(txn, localAuthor);
-		assertEquals(contactId, db.addContact(txn, author, localAuthorId,
+		assertEquals(contactId, db.addContact(txn, author, localAuthor.getId(),
 				true, true));
 		db.addTransport(txn, transportId, 123);
 		db.updateTransportKeys(txn, Collections.singletonMap(contactId, keys));
@@ -773,7 +764,7 @@ public class H2DatabaseTest extends BrambleTestCase {
 
 		// Add the contact, transport and transport keys
 		db.addLocalAuthor(txn, localAuthor);
-		assertEquals(contactId, db.addContact(txn, author, localAuthorId,
+		assertEquals(contactId, db.addContact(txn, author, localAuthor.getId(),
 				true, true));
 		db.addTransport(txn, transportId, 123);
 		db.updateTransportKeys(txn, Collections.singletonMap(contactId, keys));
@@ -808,7 +799,7 @@ public class H2DatabaseTest extends BrambleTestCase {
 		db.addLocalAuthor(txn, localAuthor);
 
 		// Add a contact associated with the local author
-		assertEquals(contactId, db.addContact(txn, author, localAuthorId,
+		assertEquals(contactId, db.addContact(txn, author, localAuthor.getId(),
 				true, true));
 
 		// Ensure contact is returned from database by Author ID
@@ -833,18 +824,19 @@ public class H2DatabaseTest extends BrambleTestCase {
 
 		// Add a local author - no contacts should be associated
 		db.addLocalAuthor(txn, localAuthor);
-		Collection<ContactId> contacts = db.getContacts(txn, localAuthorId);
+		Collection<ContactId> contacts =
+				db.getContacts(txn, localAuthor.getId());
 		assertEquals(Collections.emptyList(), contacts);
 
 		// Add a contact associated with the local author
-		assertEquals(contactId, db.addContact(txn, author, localAuthorId,
+		assertEquals(contactId, db.addContact(txn, author, localAuthor.getId(),
 				true, true));
-		contacts = db.getContacts(txn, localAuthorId);
+		contacts = db.getContacts(txn, localAuthor.getId());
 		assertEquals(Collections.singletonList(contactId), contacts);
 
 		// Remove the local author - the contact should be removed
-		db.removeLocalAuthor(txn, localAuthorId);
-		contacts = db.getContacts(txn, localAuthorId);
+		db.removeLocalAuthor(txn, localAuthor.getId());
+		contacts = db.getContacts(txn, localAuthor.getId());
 		assertEquals(Collections.emptyList(), contacts);
 		assertFalse(db.containsContact(txn, contactId));
 
@@ -859,14 +851,14 @@ public class H2DatabaseTest extends BrambleTestCase {
 
 		// Add a contact - initially there should be no offered messages
 		db.addLocalAuthor(txn, localAuthor);
-		assertEquals(contactId, db.addContact(txn, author, localAuthorId,
+		assertEquals(contactId, db.addContact(txn, author, localAuthor.getId(),
 				true, true));
 		assertEquals(0, db.countOfferedMessages(txn, contactId));
 
 		// Add some offered messages and count them
 		List<MessageId> ids = new ArrayList<>();
 		for (int i = 0; i < 10; i++) {
-			MessageId m = new MessageId(TestUtils.getRandomId());
+			MessageId m = new MessageId(getRandomId());
 			db.addOfferedMessage(txn, contactId, m);
 			ids.add(m);
 		}
@@ -875,8 +867,7 @@ public class H2DatabaseTest extends BrambleTestCase {
 		// Remove some of the offered messages and count again
 		List<MessageId> half = ids.subList(0, 5);
 		db.removeOfferedMessages(txn, contactId, half);
-		assertTrue(db.removeOfferedMessage(txn, contactId, ids.get(5)));
-		assertEquals(4, db.countOfferedMessages(txn, contactId));
+		assertEquals(5, db.countOfferedMessages(txn, contactId));
 
 		db.commitTransaction(txn);
 		db.close();
@@ -927,7 +918,7 @@ public class H2DatabaseTest extends BrambleTestCase {
 
 		// Add a group and a message
 		db.addGroup(txn, group);
-		db.addMessage(txn, message, DELIVERED, true);
+		db.addMessage(txn, message, DELIVERED, true, null);
 
 		// Attach some metadata to the message
 		Metadata metadata = new Metadata();
@@ -998,7 +989,7 @@ public class H2DatabaseTest extends BrambleTestCase {
 
 		// Add a group and a message
 		db.addGroup(txn, group);
-		db.addMessage(txn, message, DELIVERED, true);
+		db.addMessage(txn, message, DELIVERED, true, null);
 
 		// Attach some metadata to the message
 		Metadata metadata = new Metadata();
@@ -1051,7 +1042,7 @@ public class H2DatabaseTest extends BrambleTestCase {
 
 	@Test
 	public void testMetadataQueries() throws Exception {
-		MessageId messageId1 = new MessageId(TestUtils.getRandomId());
+		MessageId messageId1 = new MessageId(getRandomId());
 		Message message1 = new Message(messageId1, groupId, timestamp, raw);
 
 		Database<Connection> db = open(false);
@@ -1059,8 +1050,8 @@ public class H2DatabaseTest extends BrambleTestCase {
 
 		// Add a group and two messages
 		db.addGroup(txn, group);
-		db.addMessage(txn, message, DELIVERED, true);
-		db.addMessage(txn, message1, DELIVERED, true);
+		db.addMessage(txn, message, DELIVERED, true, null);
+		db.addMessage(txn, message1, DELIVERED, true, null);
 
 		// Attach some metadata to the messages
 		Metadata metadata = new Metadata();
@@ -1155,7 +1146,7 @@ public class H2DatabaseTest extends BrambleTestCase {
 
 	@Test
 	public void testMetadataQueriesOnlyForDeliveredMessages() throws Exception {
-		MessageId messageId1 = new MessageId(TestUtils.getRandomId());
+		MessageId messageId1 = new MessageId(getRandomId());
 		Message message1 = new Message(messageId1, groupId, timestamp, raw);
 
 		Database<Connection> db = open(false);
@@ -1163,8 +1154,8 @@ public class H2DatabaseTest extends BrambleTestCase {
 
 		// Add a group and two messages
 		db.addGroup(txn, group);
-		db.addMessage(txn, message, DELIVERED, true);
-		db.addMessage(txn, message1, DELIVERED, true);
+		db.addMessage(txn, message, DELIVERED, true, null);
+		db.addMessage(txn, message1, DELIVERED, true, null);
 
 		// Attach some metadata to the messages
 		Metadata metadata = new Metadata();
@@ -1226,10 +1217,10 @@ public class H2DatabaseTest extends BrambleTestCase {
 
 	@Test
 	public void testMessageDependencies() throws Exception {
-		MessageId messageId1 = new MessageId(TestUtils.getRandomId());
-		MessageId messageId2 = new MessageId(TestUtils.getRandomId());
-		MessageId messageId3 = new MessageId(TestUtils.getRandomId());
-		MessageId messageId4 = new MessageId(TestUtils.getRandomId());
+		MessageId messageId1 = new MessageId(getRandomId());
+		MessageId messageId2 = new MessageId(getRandomId());
+		MessageId messageId3 = new MessageId(getRandomId());
+		MessageId messageId4 = new MessageId(getRandomId());
 		Message message1 = new Message(messageId1, groupId, timestamp, raw);
 		Message message2 = new Message(messageId2, groupId, timestamp, raw);
 
@@ -1238,9 +1229,9 @@ public class H2DatabaseTest extends BrambleTestCase {
 
 		// Add a group and some messages
 		db.addGroup(txn, group);
-		db.addMessage(txn, message, PENDING, true);
-		db.addMessage(txn, message1, DELIVERED, true);
-		db.addMessage(txn, message2, INVALID, true);
+		db.addMessage(txn, message, PENDING, true, contactId);
+		db.addMessage(txn, message1, DELIVERED, true, contactId);
+		db.addMessage(txn, message2, INVALID, true, contactId);
 
 		// Add dependencies
 		db.addMessageDependency(txn, groupId, messageId, messageId1);
@@ -1307,26 +1298,26 @@ public class H2DatabaseTest extends BrambleTestCase {
 
 		// Add a group and a message
 		db.addGroup(txn, group);
-		db.addMessage(txn, message, PENDING, true);
+		db.addMessage(txn, message, PENDING, true, contactId);
 
 		// Add a second group
-		GroupId groupId1 = new GroupId(TestUtils.getRandomId());
+		GroupId groupId1 = new GroupId(getRandomId());
 		Group group1 = new Group(groupId1, clientId,
-				TestUtils.getRandomBytes(MAX_GROUP_DESCRIPTOR_LENGTH));
+				getRandomBytes(MAX_GROUP_DESCRIPTOR_LENGTH));
 		db.addGroup(txn, group1);
 
 		// Add a message to the second group
-		MessageId messageId1 = new MessageId(TestUtils.getRandomId());
+		MessageId messageId1 = new MessageId(getRandomId());
 		Message message1 = new Message(messageId1, groupId1, timestamp, raw);
-		db.addMessage(txn, message1, DELIVERED, true);
+		db.addMessage(txn, message1, DELIVERED, true, contactId);
 
 		// Create an ID for a missing message
-		MessageId messageId2 = new MessageId(TestUtils.getRandomId());
+		MessageId messageId2 = new MessageId(getRandomId());
 
 		// Add another message to the first group
-		MessageId messageId3 = new MessageId(TestUtils.getRandomId());
+		MessageId messageId3 = new MessageId(getRandomId());
 		Message message3 = new Message(messageId3, groupId, timestamp, raw);
-		db.addMessage(txn, message3, DELIVERED, true);
+		db.addMessage(txn, message3, DELIVERED, true, contactId);
 
 		// Add dependencies between the messages
 		db.addMessageDependency(txn, groupId, messageId, messageId1);
@@ -1359,10 +1350,10 @@ public class H2DatabaseTest extends BrambleTestCase {
 
 	@Test
 	public void testGetPendingMessagesForDelivery() throws Exception {
-		MessageId mId1 = new MessageId(TestUtils.getRandomId());
-		MessageId mId2 = new MessageId(TestUtils.getRandomId());
-		MessageId mId3 = new MessageId(TestUtils.getRandomId());
-		MessageId mId4 = new MessageId(TestUtils.getRandomId());
+		MessageId mId1 = new MessageId(getRandomId());
+		MessageId mId2 = new MessageId(getRandomId());
+		MessageId mId3 = new MessageId(getRandomId());
+		MessageId mId4 = new MessageId(getRandomId());
 		Message m1 = new Message(mId1, groupId, timestamp, raw);
 		Message m2 = new Message(mId2, groupId, timestamp, raw);
 		Message m3 = new Message(mId3, groupId, timestamp, raw);
@@ -1373,20 +1364,20 @@ public class H2DatabaseTest extends BrambleTestCase {
 
 		// Add a group and some messages with different states
 		db.addGroup(txn, group);
-		db.addMessage(txn, m1, UNKNOWN, true);
-		db.addMessage(txn, m2, INVALID, true);
-		db.addMessage(txn, m3, PENDING, true);
-		db.addMessage(txn, m4, DELIVERED, true);
+		db.addMessage(txn, m1, UNKNOWN, true, contactId);
+		db.addMessage(txn, m2, INVALID, true, contactId);
+		db.addMessage(txn, m3, PENDING, true, contactId);
+		db.addMessage(txn, m4, DELIVERED, true, contactId);
 
 		Collection<MessageId> result;
 
 		// Retrieve messages to be validated
-		result = db.getMessagesToValidate(txn, clientId);
+		result = db.getMessagesToValidate(txn);
 		assertEquals(1, result.size());
 		assertTrue(result.contains(mId1));
 
 		// Retrieve pending messages
-		result = db.getPendingMessages(txn, clientId);
+		result = db.getPendingMessages(txn);
 		assertEquals(1, result.size());
 		assertTrue(result.contains(mId3));
 
@@ -1396,10 +1387,10 @@ public class H2DatabaseTest extends BrambleTestCase {
 
 	@Test
 	public void testGetMessagesToShare() throws Exception {
-		MessageId mId1 = new MessageId(TestUtils.getRandomId());
-		MessageId mId2 = new MessageId(TestUtils.getRandomId());
-		MessageId mId3 = new MessageId(TestUtils.getRandomId());
-		MessageId mId4 = new MessageId(TestUtils.getRandomId());
+		MessageId mId1 = new MessageId(getRandomId());
+		MessageId mId2 = new MessageId(getRandomId());
+		MessageId mId3 = new MessageId(getRandomId());
+		MessageId mId4 = new MessageId(getRandomId());
 		Message m1 = new Message(mId1, groupId, timestamp, raw);
 		Message m2 = new Message(mId2, groupId, timestamp, raw);
 		Message m3 = new Message(mId3, groupId, timestamp, raw);
@@ -1410,10 +1401,10 @@ public class H2DatabaseTest extends BrambleTestCase {
 
 		// Add a group and some messages
 		db.addGroup(txn, group);
-		db.addMessage(txn, m1, DELIVERED, true);
-		db.addMessage(txn, m2, DELIVERED, false);
-		db.addMessage(txn, m3, DELIVERED, false);
-		db.addMessage(txn, m4, DELIVERED, true);
+		db.addMessage(txn, m1, DELIVERED, true, contactId);
+		db.addMessage(txn, m2, DELIVERED, false, contactId);
+		db.addMessage(txn, m3, DELIVERED, false, contactId);
+		db.addMessage(txn, m4, DELIVERED, true, contactId);
 
 		// Introduce dependencies between the messages
 		db.addMessageDependency(txn, groupId, mId1, mId2);
@@ -1421,8 +1412,7 @@ public class H2DatabaseTest extends BrambleTestCase {
 		db.addMessageDependency(txn, groupId, mId4, mId3);
 
 		// Retrieve messages to be shared
-		Collection<MessageId> result =
-				db.getMessagesToShare(txn, clientId);
+		Collection<MessageId> result = db.getMessagesToShare(txn);
 		assertEquals(2, result.size());
 		assertTrue(result.contains(mId2));
 		assertTrue(result.contains(mId3));
@@ -1438,12 +1428,11 @@ public class H2DatabaseTest extends BrambleTestCase {
 
 		// Add a contact, a shared group and a shared message
 		db.addLocalAuthor(txn, localAuthor);
-		assertEquals(contactId, db.addContact(txn, author, localAuthorId,
+		assertEquals(contactId, db.addContact(txn, author, localAuthor.getId(),
 				true, true));
 		db.addGroup(txn, group);
 		db.addGroupVisibility(txn, contactId, groupId, true);
-		db.addMessage(txn, message, DELIVERED, true);
-		db.addStatus(txn, contactId, messageId, false, false);
+		db.addMessage(txn, message, DELIVERED, true, null);
 
 		// The message should not be sent or seen
 		MessageStatus status = db.getMessageStatus(txn, contactId, messageId);
@@ -1507,9 +1496,7 @@ public class H2DatabaseTest extends BrambleTestCase {
 	@Test
 	public void testDifferentLocalAuthorsCanHaveTheSameContact()
 			throws Exception {
-		AuthorId localAuthorId1 = new AuthorId(TestUtils.getRandomId());
-		LocalAuthor localAuthor1 = new LocalAuthor(localAuthorId1, "Carol",
-				new byte[MAX_PUBLIC_KEY_LENGTH], new byte[123], timestamp);
+		LocalAuthor localAuthor1 = getLocalAuthor();
 
 		Database<Connection> db = open(false);
 		Connection txn = db.startTransaction();
@@ -1520,15 +1507,15 @@ public class H2DatabaseTest extends BrambleTestCase {
 
 		// Add the same contact for each local author
 		ContactId contactId =
-				db.addContact(txn, author, localAuthorId, true, true);
+				db.addContact(txn, author, localAuthor.getId(), true, true);
 		ContactId contactId1 =
-				db.addContact(txn, author, localAuthorId1, true, true);
+				db.addContact(txn, author, localAuthor1.getId(), true, true);
 
 		// The contacts should be distinct
 		assertNotEquals(contactId, contactId1);
 		assertEquals(2, db.getContacts(txn).size());
-		assertEquals(1, db.getContacts(txn, localAuthorId).size());
-		assertEquals(1, db.getContacts(txn, localAuthorId1).size());
+		assertEquals(1, db.getContacts(txn, localAuthor.getId()).size());
+		assertEquals(1, db.getContacts(txn, localAuthor1.getId()).size());
 
 		db.commitTransaction(txn);
 		db.close();
@@ -1541,12 +1528,11 @@ public class H2DatabaseTest extends BrambleTestCase {
 
 		// Add a contact, a shared group and a shared message
 		db.addLocalAuthor(txn, localAuthor);
-		assertEquals(contactId, db.addContact(txn, author, localAuthorId,
+		assertEquals(contactId, db.addContact(txn, author, localAuthor.getId(),
 				true, true));
 		db.addGroup(txn, group);
 		db.addGroupVisibility(txn, contactId, groupId, true);
-		db.addMessage(txn, message, DELIVERED, true);
-		db.addStatus(txn, contactId, messageId, false, false);
+		db.addMessage(txn, message, DELIVERED, true, null);
 
 		// The message should be visible to the contact
 		assertTrue(db.containsVisibleMessage(txn, contactId, messageId));
@@ -1587,7 +1573,7 @@ public class H2DatabaseTest extends BrambleTestCase {
 
 		// Add a contact
 		db.addLocalAuthor(txn, localAuthor);
-		assertEquals(contactId, db.addContact(txn, author, localAuthorId,
+		assertEquals(contactId, db.addContact(txn, author, localAuthor.getId(),
 				true, true));
 
 		// The contact should be active
@@ -1620,7 +1606,7 @@ public class H2DatabaseTest extends BrambleTestCase {
 
 		// Add a group and a message
 		db.addGroup(txn, group);
-		db.addMessage(txn, message, UNKNOWN, false);
+		db.addMessage(txn, message, UNKNOWN, false, contactId);
 
 		// Walk the message through the validation and delivery states
 		assertEquals(UNKNOWN, db.getMessageState(txn, messageId));
@@ -1635,6 +1621,56 @@ public class H2DatabaseTest extends BrambleTestCase {
 		db.close();
 	}
 
+	@Test
+	public void testGetNextSendTime() throws Exception {
+		long now = System.currentTimeMillis();
+		Database<Connection> db = open(false, new StoppedClock(now));
+		Connection txn = db.startTransaction();
+
+		// Add a contact, a group and a message
+		db.addLocalAuthor(txn, localAuthor);
+		assertEquals(contactId, db.addContact(txn, author, localAuthor.getId(),
+				true, true));
+		db.addGroup(txn, group);
+		db.addMessage(txn, message, UNKNOWN, false, null);
+
+		// There should be no messages to send
+		assertEquals(Long.MAX_VALUE, db.getNextSendTime(txn, contactId));
+
+		// Share the group with the contact - still no messages to send
+		db.addGroupVisibility(txn, contactId, groupId, true);
+		assertEquals(Long.MAX_VALUE, db.getNextSendTime(txn, contactId));
+
+		// Set the message's state to DELIVERED - still no messages to send
+		db.setMessageState(txn, messageId, DELIVERED);
+		assertEquals(Long.MAX_VALUE, db.getNextSendTime(txn, contactId));
+
+		// Share the message - now it should be sendable immediately
+		db.setMessageShared(txn, messageId);
+		assertEquals(0, db.getNextSendTime(txn, contactId));
+
+		// Mark the message as requested - it should still be sendable
+		db.raiseRequestedFlag(txn, contactId, messageId);
+		assertEquals(0, db.getNextSendTime(txn, contactId));
+
+		// Update the message's expiry time as though we sent it - now the
+		// message should be sendable after one round-trip
+		db.updateExpiryTime(txn, contactId, messageId, 1000);
+		assertEquals(now + 2000, db.getNextSendTime(txn, contactId));
+
+		// Update the message's expiry time again - now it should be sendable
+		// after two round-trips
+		db.updateExpiryTime(txn, contactId, messageId, 1000);
+		assertEquals(now + 4000, db.getNextSendTime(txn, contactId));
+
+		// Delete the message - there should be no messages to send
+		db.deleteMessage(txn, messageId);
+		assertEquals(Long.MAX_VALUE, db.getNextSendTime(txn, contactId));
+
+		db.commitTransaction(txn);
+		db.close();
+	}
+
 	@Test
 	public void testExceptionHandling() throws Exception {
 		Database<Connection> db = open(false);
@@ -1652,28 +1688,33 @@ public class H2DatabaseTest extends BrambleTestCase {
 	}
 
 	private Database<Connection> open(boolean resume) throws Exception {
+		return open(resume, new SystemClock());
+	}
+
+	private Database<Connection> open(boolean resume, Clock clock)
+			throws Exception {
 		Database<Connection> db = new H2Database(new TestDatabaseConfig(testDir,
-				MAX_SIZE), new SystemClock());
+				MAX_SIZE), clock);
 		if (!resume) TestUtils.deleteTestDirectory(testDir);
-		db.open();
+		db.open(null);
 		return db;
 	}
 
 	private TransportKeys createTransportKeys() {
-		SecretKey inPrevTagKey = TestUtils.getSecretKey();
-		SecretKey inPrevHeaderKey = TestUtils.getSecretKey();
+		SecretKey inPrevTagKey = getSecretKey();
+		SecretKey inPrevHeaderKey = getSecretKey();
 		IncomingKeys inPrev = new IncomingKeys(inPrevTagKey, inPrevHeaderKey,
 				1, 123, new byte[4]);
-		SecretKey inCurrTagKey = TestUtils.getSecretKey();
-		SecretKey inCurrHeaderKey = TestUtils.getSecretKey();
+		SecretKey inCurrTagKey = getSecretKey();
+		SecretKey inCurrHeaderKey = getSecretKey();
 		IncomingKeys inCurr = new IncomingKeys(inCurrTagKey, inCurrHeaderKey,
 				2, 234, new byte[4]);
-		SecretKey inNextTagKey = TestUtils.getSecretKey();
-		SecretKey inNextHeaderKey = TestUtils.getSecretKey();
+		SecretKey inNextTagKey = getSecretKey();
+		SecretKey inNextHeaderKey = getSecretKey();
 		IncomingKeys inNext = new IncomingKeys(inNextTagKey, inNextHeaderKey,
 				3, 345, new byte[4]);
-		SecretKey outCurrTagKey = TestUtils.getSecretKey();
-		SecretKey outCurrHeaderKey = TestUtils.getSecretKey();
+		SecretKey outCurrTagKey = getSecretKey();
+		SecretKey outCurrHeaderKey = getSecretKey();
 		OutgoingKeys outCurr = new OutgoingKeys(outCurrTagKey, outCurrHeaderKey,
 				2, 456);
 		return new TransportKeys(transportId, inPrev, inCurr, inNext, outCurr);
@@ -1683,4 +1724,23 @@ public class H2DatabaseTest extends BrambleTestCase {
 	public void tearDown() {
 		TestUtils.deleteTestDirectory(testDir);
 	}
+
+	private static class StoppedClock implements Clock {
+
+		private final long time;
+
+		private StoppedClock(long time) {
+			this.time = time;
+		}
+
+		@Override
+		public long currentTimeMillis() {
+			return time;
+		}
+
+		@Override
+		public void sleep(long milliseconds) throws InterruptedException {
+			Thread.sleep(milliseconds);
+		}
+	}
 }

bramble-core/src/test/java/org/briarproject/bramble/db/H2MigrationTest.java

@@ -0,0 +1,21 @@
+package org.briarproject.bramble.db;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import java.sql.Connection;
+import java.util.List;
+
+@NotNullByDefault
+public class H2MigrationTest extends DatabaseMigrationTest {
+
+	@Override
+	Database<Connection> createDatabase(List<Migration<Connection>> migrations)
+			throws Exception {
+		return new H2Database(config, clock) {
+			@Override
+			List<Migration<Connection>> getMigrations() {
+				return migrations;
+			}
+		};
+	}
+}

bramble-core/src/test/java/org/briarproject/bramble/db/Migration30_31Test.java

@@ -0,0 +1,281 @@
+package org.briarproject.bramble.db;
+
+import org.briarproject.bramble.api.db.Metadata;
+import org.briarproject.bramble.api.sync.GroupId;
+import org.briarproject.bramble.api.sync.Message;
+import org.briarproject.bramble.api.sync.MessageId;
+import org.briarproject.bramble.api.sync.ValidationManager.State;
+import org.briarproject.bramble.test.BrambleTestCase;
+import org.briarproject.bramble.test.TestUtils;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+
+import java.io.File;
+import java.sql.Connection;
+import java.sql.DriverManager;
+import java.sql.PreparedStatement;
+import java.sql.ResultSet;
+import java.sql.SQLException;
+import java.sql.Statement;
+import java.util.Map.Entry;
+
+import static junit.framework.TestCase.assertNotNull;
+import static junit.framework.TestCase.assertTrue;
+import static org.briarproject.bramble.api.sync.ValidationManager.State.DELIVERED;
+import static org.briarproject.bramble.api.sync.ValidationManager.State.UNKNOWN;
+import static org.briarproject.bramble.test.TestUtils.getMessage;
+import static org.briarproject.bramble.test.TestUtils.getRandomBytes;
+import static org.briarproject.bramble.test.TestUtils.getRandomId;
+import static org.briarproject.bramble.util.StringUtils.getRandomString;
+import static org.junit.Assert.assertArrayEquals;
+import static org.junit.Assert.assertEquals;
+
+public class Migration30_31Test extends BrambleTestCase {
+
+	private static final String CREATE_GROUPS_STUB =
+			"CREATE TABLE groups"
+					+ " (groupId BINARY(32) NOT NULL,"
+					+ " PRIMARY KEY (groupId))";
+
+	private static final String CREATE_MESSAGES =
+			"CREATE TABLE messages"
+					+ " (messageId BINARY(32) NOT NULL,"
+					+ " groupId BINARY(32) NOT NULL,"
+					+ " timestamp BIGINT NOT NULL,"
+					+ " state INT NOT NULL,"
+					+ " shared BOOLEAN NOT NULL,"
+					+ " length INT NOT NULL,"
+					+ " raw BLOB," // Null if message has been deleted
+					+ " PRIMARY KEY (messageId),"
+					+ " FOREIGN KEY (groupId)"
+					+ " REFERENCES groups (groupId)"
+					+ " ON DELETE CASCADE)";
+
+	private static final String CREATE_MESSAGE_METADATA_30 =
+			"CREATE TABLE messageMetadata"
+					+ " (messageId BINARY(32) NOT NULL,"
+					+ " key VARCHAR NOT NULL,"
+					+ " value BINARY NOT NULL,"
+					+ " PRIMARY KEY (messageId, key),"
+					+ " FOREIGN KEY (messageId)"
+					+ " REFERENCES messages (messageId)"
+					+ " ON DELETE CASCADE)";
+
+	private final File testDir = TestUtils.getTestDirectory();
+	private final File db = new File(testDir, "db");
+	private final String url = "jdbc:h2:" + db.getAbsolutePath();
+	private final GroupId groupId = new GroupId(getRandomId());
+	private final GroupId groupId1 = new GroupId(getRandomId());
+	private final Message message = getMessage(groupId);
+	private final Message message1 = getMessage(groupId1);
+	private final Metadata meta = new Metadata(), meta1 = new Metadata();
+
+	private Connection connection = null;
+
+	public Migration30_31Test() {
+		for (int i = 0; i < 10; i++) {
+			meta.put(getRandomString(123 + i), getRandomBytes(123 + i));
+			meta1.put(getRandomString(123 + i), getRandomBytes(123 + i));
+		}
+	}
+
+	@Before
+	public void setUp() throws Exception {
+		assertTrue(testDir.mkdirs());
+		Class.forName("org.h2.Driver");
+		connection = DriverManager.getConnection(url);
+	}
+
+	@After
+	public void tearDown() throws Exception {
+		if (connection != null) connection.close();
+		TestUtils.deleteTestDirectory(testDir);
+	}
+
+	@Test
+	public void testMigration() throws Exception {
+		try {
+			Statement s = connection.createStatement();
+			s.execute(CREATE_GROUPS_STUB);
+			s.execute(CREATE_MESSAGES);
+			s.execute(CREATE_MESSAGE_METADATA_30);
+			s.close();
+
+			addGroup(groupId);
+			addMessage(message, DELIVERED, true);
+			addMessageMetadata30(message, meta);
+			assertMetadataEquals(meta, getMessageMetadata(message.getId()));
+
+			addGroup(groupId1);
+			addMessage(message1, UNKNOWN, false);
+			addMessageMetadata30(message1, meta1);
+			assertMetadataEquals(meta1, getMessageMetadata(message1.getId()));
+
+			new Migration30_31().migrate(connection);
+
+			assertMetadataEquals(meta, getMessageMetadata(message.getId()));
+			for (String key : meta.keySet()) {
+				GroupId g = getMessageMetadataGroupId31(message.getId(), key);
+				assertEquals(groupId, g);
+				State state = getMessageMetadataState31(message.getId(), key);
+				assertEquals(DELIVERED, state);
+			}
+
+			assertMetadataEquals(meta1, getMessageMetadata(message1.getId()));
+			for (String key : meta1.keySet()) {
+				GroupId g = getMessageMetadataGroupId31(message1.getId(), key);
+				assertEquals(groupId1, g);
+				State state = getMessageMetadataState31(message1.getId(), key);
+				assertEquals(UNKNOWN, state);
+			}
+		} catch (SQLException e) {
+			connection.close();
+			throw e;
+		}
+	}
+
+	private void addGroup(GroupId g) throws SQLException {
+		PreparedStatement ps = null;
+		try {
+			String sql = "INSERT INTO groups (groupId) VALUES (?)";
+			ps = connection.prepareStatement(sql);
+			ps.setBytes(1, g.getBytes());
+			int affected = ps.executeUpdate();
+			if (affected != 1) throw new DbStateException();
+			ps.close();
+		} catch (SQLException e) {
+			if (ps != null) ps.close();
+			throw e;
+		}
+	}
+
+	private void addMessage(Message m, State state, boolean shared)
+			throws SQLException {
+		PreparedStatement ps = null;
+		try {
+			String sql = "INSERT INTO messages (messageId, groupId, timestamp,"
+					+ " state, shared, length, raw)"
+					+ " VALUES (?, ?, ?, ?, ?, ?, ?)";
+			ps = connection.prepareStatement(sql);
+			ps.setBytes(1, m.getId().getBytes());
+			ps.setBytes(2, m.getGroupId().getBytes());
+			ps.setLong(3, m.getTimestamp());
+			ps.setInt(4, state.getValue());
+			ps.setBoolean(5, shared);
+			byte[] raw = m.getRaw();
+			ps.setInt(6, raw.length);
+			ps.setBytes(7, raw);
+			int affected = ps.executeUpdate();
+			if (affected != 1) throw new DbStateException();
+			ps.close();
+		} catch (SQLException e) {
+			if (ps != null) ps.close();
+			throw e;
+		}
+	}
+
+	private void addMessageMetadata30(Message m, Metadata meta)
+			throws SQLException {
+		PreparedStatement ps = null;
+		try {
+			String sql = "INSERT INTO messageMetadata"
+					+ " (messageId, key, value)"
+					+ " VALUES (?, ?, ?)";
+			ps = connection.prepareStatement(sql);
+			ps.setBytes(1, m.getId().getBytes());
+			for (Entry<String, byte[]> e : meta.entrySet()) {
+				ps.setString(2, e.getKey());
+				ps.setBytes(3, e.getValue());
+				ps.addBatch();
+			}
+			int[] batchAffected = ps.executeBatch();
+			if (batchAffected.length != meta.size())
+				throw new DbStateException();
+			for (int rows : batchAffected)
+				if (rows != 1) throw new DbStateException();
+			ps.close();
+		} catch (SQLException e) {
+			if (ps != null) ps.close();
+			throw e;
+		}
+	}
+
+	private Metadata getMessageMetadata(MessageId m) throws SQLException {
+		PreparedStatement ps = null;
+		ResultSet rs = null;
+		try {
+			String sql = "SELECT key, value FROM messageMetadata"
+					+ " WHERE messageId = ?";
+			ps = connection.prepareStatement(sql);
+			ps.setBytes(1, m.getBytes());
+			rs = ps.executeQuery();
+			Metadata meta = new Metadata();
+			while (rs.next()) meta.put(rs.getString(1), rs.getBytes(2));
+			rs.close();
+			ps.close();
+			return meta;
+		} catch (SQLException e) {
+			if (rs != null) rs.close();
+			if (ps != null) ps.close();
+			throw e;
+		}
+	}
+
+	private GroupId getMessageMetadataGroupId31(MessageId m, String key)
+		throws SQLException {
+		PreparedStatement ps = null;
+		ResultSet rs = null;
+		try {
+			String sql = "SELECT groupId FROM messageMetadata"
+					+ " WHERE messageId = ? AND key = ?";
+			ps = connection.prepareStatement(sql);
+			ps.setBytes(1, m.getBytes());
+			ps.setString(2, key);
+			rs = ps.executeQuery();
+			if (!rs.next()) throw new DbStateException();
+			GroupId g = new GroupId(rs.getBytes(1));
+			if (rs.next()) throw new DbStateException();
+			rs.close();
+			ps.close();
+			return g;
+		} catch (SQLException e) {
+			if (rs != null) rs.close();
+			if (ps != null) ps.close();
+			throw e;
+		}
+	}
+
+	private State getMessageMetadataState31(MessageId m, String key)
+		throws SQLException {
+		PreparedStatement ps = null;
+		ResultSet rs = null;
+		try {
+			String sql = "SELECT state FROM messageMetadata"
+					+ " WHERE messageId = ? AND key = ?";
+			ps = connection.prepareStatement(sql);
+			ps.setBytes(1, m.getBytes());
+			ps.setString(2, key);
+			rs = ps.executeQuery();
+			if (!rs.next()) throw new DbStateException();
+			State state = State.fromValue(rs.getInt(1));
+			if (rs.next()) throw new DbStateException();
+			rs.close();
+			ps.close();
+			return state;
+		} catch (SQLException e) {
+			if (rs != null) rs.close();
+			if (ps != null) ps.close();
+			throw e;
+		}
+	}
+
+	private void assertMetadataEquals(Metadata expected, Metadata actual) {
+		assertEquals(expected.size(), actual.size());
+		for (Entry<String, byte[]> e : expected.entrySet()) {
+			byte[] value = actual.get(e.getKey());
+			assertNotNull(value);
+			assertArrayEquals(e.getValue(), value);
+		}
+	}
+}

bramble-core/src/test/java/org/briarproject/bramble/db/Migration31_32Test.java

@@ -0,0 +1,369 @@
+package org.briarproject.bramble.db;
+
+import org.briarproject.bramble.api.contact.ContactId;
+import org.briarproject.bramble.api.sync.GroupId;
+import org.briarproject.bramble.api.sync.Message;
+import org.briarproject.bramble.api.sync.MessageId;
+import org.briarproject.bramble.api.sync.ValidationManager.State;
+import org.briarproject.bramble.test.BrambleTestCase;
+import org.briarproject.bramble.test.TestUtils;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+
+import java.io.File;
+import java.sql.Connection;
+import java.sql.DriverManager;
+import java.sql.PreparedStatement;
+import java.sql.ResultSet;
+import java.sql.SQLException;
+import java.sql.Statement;
+
+import static java.sql.Types.BINARY;
+import static junit.framework.Assert.assertFalse;
+import static junit.framework.TestCase.assertTrue;
+import static org.briarproject.bramble.api.sync.ValidationManager.State.DELIVERED;
+import static org.briarproject.bramble.api.sync.ValidationManager.State.UNKNOWN;
+import static org.briarproject.bramble.test.TestUtils.getMessage;
+import static org.briarproject.bramble.test.TestUtils.getRandomId;
+import static org.junit.Assert.assertEquals;
+
+public class Migration31_32Test extends BrambleTestCase {
+
+	private static final String CREATE_GROUPS_STUB =
+			"CREATE TABLE groups"
+					+ " (groupId BINARY(32) NOT NULL,"
+					+ " PRIMARY KEY (groupId))";
+
+	private static final String CREATE_CONTACTS_STUB =
+			"CREATE TABLE contacts"
+					+ " (contactId INT NOT NULL,"
+					+ " PRIMARY KEY (contactId))";
+
+	private static final String CREATE_GROUP_VISIBILITIES_STUB =
+			"CREATE TABLE groupVisibilities"
+					+ " (contactId INT NOT NULL,"
+					+ " groupId BINARY(32) NOT NULL,"
+					+ " shared BOOLEAN NOT NULL,"
+					+ " PRIMARY KEY (contactId, groupId))";
+
+	private static final String CREATE_MESSAGES =
+			"CREATE TABLE messages"
+					+ " (messageId BINARY(32) NOT NULL,"
+					+ " groupId BINARY(32) NOT NULL,"
+					+ " timestamp BIGINT NOT NULL,"
+					+ " state INT NOT NULL,"
+					+ " shared BOOLEAN NOT NULL,"
+					+ " length INT NOT NULL,"
+					+ " raw BLOB," // Null if message has been deleted
+					+ " PRIMARY KEY (messageId),"
+					+ " FOREIGN KEY (groupId)"
+					+ " REFERENCES groups (groupId)"
+					+ " ON DELETE CASCADE)";
+
+	private static final String CREATE_STATUSES_31 =
+			"CREATE TABLE statuses"
+					+ " (messageId BINARY(32) NOT NULL,"
+					+ " contactId INT NOT NULL,"
+					+ " ack BOOLEAN NOT NULL,"
+					+ " seen BOOLEAN NOT NULL,"
+					+ " requested BOOLEAN NOT NULL,"
+					+ " expiry BIGINT NOT NULL,"
+					+ " txCount INT NOT NULL,"
+					+ " PRIMARY KEY (messageId, contactId),"
+					+ " FOREIGN KEY (messageId)"
+					+ " REFERENCES messages (messageId)"
+					+ " ON DELETE CASCADE,"
+					+ " FOREIGN KEY (contactId)"
+					+ " REFERENCES contacts (contactId)"
+					+ " ON DELETE CASCADE)";
+
+	private final File testDir = TestUtils.getTestDirectory();
+	private final File db = new File(testDir, "db");
+	private final String url = "jdbc:h2:" + db.getAbsolutePath();
+	private final GroupId groupId = new GroupId(getRandomId());
+	private final GroupId groupId1 = new GroupId(getRandomId());
+	private final ContactId contactId = new ContactId(123);
+	private final ContactId contactId1 = new ContactId(234);
+	private final Message message = getMessage(groupId);
+	private final Message message1 = getMessage(groupId1);
+	private final Message message2 = getMessage(groupId1);
+
+	private Connection connection = null;
+
+	@Before
+	public void setUp() throws Exception {
+		assertTrue(testDir.mkdirs());
+		Class.forName("org.h2.Driver");
+		connection = DriverManager.getConnection(url);
+	}
+
+	@After
+	public void tearDown() throws Exception {
+		if (connection != null) connection.close();
+		TestUtils.deleteTestDirectory(testDir);
+	}
+
+	@Test
+	public void testMigration() throws Exception {
+		try {
+			Statement s = connection.createStatement();
+			s.execute(CREATE_GROUPS_STUB);
+			s.execute(CREATE_CONTACTS_STUB);
+			s.execute(CREATE_GROUP_VISIBILITIES_STUB);
+			s.execute(CREATE_MESSAGES);
+			s.execute(CREATE_STATUSES_31);
+			s.close();
+
+			addGroup(groupId);
+			addMessage(message, DELIVERED, true, false);
+
+			addGroup(groupId1);
+			addMessage(message1, UNKNOWN, false, false);
+			addMessage(message2, DELIVERED, true, true);
+
+			addContact(contactId);
+
+			addGroupVisibility(contactId, groupId, true);
+			addStatus31(message.getId(), contactId);
+
+			addGroupVisibility(contactId, groupId1, false);
+			addStatus31(message1.getId(), contactId);
+			addStatus31(message2.getId(), contactId);
+
+			addContact(contactId1);
+
+			addGroupVisibility(contactId1, groupId1, true);
+			addStatus31(message1.getId(), contactId1);
+			addStatus31(message2.getId(), contactId1);
+
+			new Migration31_32().migrate(connection);
+
+			assertTrue(containsStatus(message.getId(), contactId));
+			Status32 status = getStatus32(message.getId(), contactId);
+			assertEquals(groupId, status.groupId);
+			assertEquals(message.getTimestamp(), status.timestamp);
+			assertEquals(message.getLength(), status.length);
+			assertEquals(DELIVERED, status.state);
+			assertTrue(status.groupShared);
+			assertTrue(status.messageShared);
+			assertFalse(status.deleted);
+
+			assertTrue(containsStatus(message1.getId(), contactId));
+			status = getStatus32(message1.getId(), contactId);
+			assertEquals(groupId1, status.groupId);
+			assertEquals(message1.getTimestamp(), status.timestamp);
+			assertEquals(message1.getLength(), status.length);
+			assertEquals(UNKNOWN, status.state);
+			assertFalse(status.groupShared);
+			assertFalse(status.messageShared);
+			assertFalse(status.deleted);
+
+			assertTrue(containsStatus(message2.getId(), contactId));
+			status = getStatus32(message2.getId(), contactId);
+			assertEquals(groupId1, status.groupId);
+			assertEquals(message2.getTimestamp(), status.timestamp);
+			assertEquals(message2.getLength(), status.length);
+			assertEquals(DELIVERED, status.state);
+			assertFalse(status.groupShared);
+			assertTrue(status.messageShared);
+			assertTrue(status.deleted);
+
+			assertFalse(containsStatus(message.getId(), contactId1));
+
+			assertTrue(containsStatus(message1.getId(), contactId1));
+			status = getStatus32(message1.getId(), contactId1);
+			assertEquals(groupId1, status.groupId);
+			assertEquals(message1.getTimestamp(), status.timestamp);
+			assertEquals(message1.getLength(), status.length);
+			assertEquals(UNKNOWN, status.state);
+			assertTrue(status.groupShared);
+			assertFalse(status.messageShared);
+			assertFalse(status.deleted);
+
+			assertTrue(containsStatus(message2.getId(), contactId1));
+			status = getStatus32(message2.getId(), contactId1);
+			assertEquals(groupId1, status.groupId);
+			assertEquals(message2.getTimestamp(), status.timestamp);
+			assertEquals(message2.getLength(), status.length);
+			assertEquals(DELIVERED, status.state);
+			assertTrue(status.groupShared);
+			assertTrue(status.messageShared);
+			assertTrue(status.deleted);
+		} catch (SQLException e) {
+			connection.close();
+			throw e;
+		}
+	}
+
+	private void addGroup(GroupId g) throws SQLException {
+		PreparedStatement ps = null;
+		try {
+			String sql = "INSERT INTO groups (groupId) VALUES (?)";
+			ps = connection.prepareStatement(sql);
+			ps.setBytes(1, g.getBytes());
+			int affected = ps.executeUpdate();
+			if (affected != 1) throw new DbStateException();
+			ps.close();
+		} catch (SQLException e) {
+			if (ps != null) ps.close();
+			throw e;
+		}
+	}
+
+	private void addContact(ContactId c) throws SQLException {
+		PreparedStatement ps = null;
+		try {
+			String sql = "INSERT INTO contacts (contactId) VALUES (?)";
+			ps = connection.prepareStatement(sql);
+			ps.setInt(1, c.getInt());
+			int affected = ps.executeUpdate();
+			if (affected != 1) throw new DbStateException();
+			ps.close();
+		} catch (SQLException e) {
+			if (ps != null) ps.close();
+			throw e;
+		}
+	}
+
+	private void addGroupVisibility(ContactId c, GroupId g, boolean shared)
+			throws SQLException {
+		PreparedStatement ps = null;
+		try {
+			String sql = "INSERT INTO groupVisibilities"
+					+ " (contactId, groupId, shared) VALUES (?, ?, ?)";
+			ps = connection.prepareStatement(sql);
+			ps.setInt(1, c.getInt());
+			ps.setBytes(2, g.getBytes());
+			ps.setBoolean(3, shared);
+			int affected = ps.executeUpdate();
+			if (affected != 1) throw new DbStateException();
+			ps.close();
+		} catch (SQLException e) {
+			if (ps != null) ps.close();
+			throw e;
+		}
+	}
+
+	private void addMessage(Message m, State state, boolean shared,
+			boolean deleted) throws SQLException {
+		PreparedStatement ps = null;
+		try {
+			String sql = "INSERT INTO messages (messageId, groupId, timestamp,"
+					+ " state, shared, length, raw)"
+					+ " VALUES (?, ?, ?, ?, ?, ?, ?)";
+			ps = connection.prepareStatement(sql);
+			ps.setBytes(1, m.getId().getBytes());
+			ps.setBytes(2, m.getGroupId().getBytes());
+			ps.setLong(3, m.getTimestamp());
+			ps.setInt(4, state.getValue());
+			ps.setBoolean(5, shared);
+			byte[] raw = m.getRaw();
+			ps.setInt(6, raw.length);
+			if (deleted) ps.setNull(7, BINARY);
+			else ps.setBytes(7, raw);
+			int affected = ps.executeUpdate();
+			if (affected != 1) throw new DbStateException();
+			ps.close();
+		} catch (SQLException e) {
+			if (ps != null) ps.close();
+			throw e;
+		}
+	}
+
+	private void addStatus31(MessageId m, ContactId c) throws SQLException {
+		PreparedStatement ps = null;
+		try {
+			String sql = "INSERT INTO statuses (messageId, contactId, ack,"
+					+ " seen, requested, expiry, txCount)"
+					+ " VALUES (?, ?, FALSE, FALSE, FALSE, 0, 0)";
+			ps = connection.prepareStatement(sql);
+			ps.setBytes(1, m.getBytes());
+			ps.setInt(2, c.getInt());
+			int affected = ps.executeUpdate();
+			if (affected != 1) throw new DbStateException();
+			ps.close();
+		} catch (SQLException e) {
+			if (ps != null) ps.close();
+			throw e;
+		}
+	}
+
+	private boolean containsStatus(MessageId m, ContactId c)
+			throws SQLException {
+		PreparedStatement ps = null;
+		ResultSet rs = null;
+		try {
+			String sql = "SELECT COUNT (*) FROM statuses"
+					+ " WHERE messageId = ? AND contactId = ?";
+			ps = connection.prepareStatement(sql);
+			ps.setBytes(1, m.getBytes());
+			ps.setInt(2, c.getInt());
+			rs = ps.executeQuery();
+			if (!rs.next()) throw new DbStateException();
+			int count = rs.getInt(1);
+			if (count < 0 || count > 1) throw new DbStateException();
+			if (rs.next()) throw new DbStateException();
+			rs.close();
+			ps.close();
+			return count > 0;
+		} catch (SQLException e) {
+			if (rs != null) rs.close();
+			if (ps != null) ps.close();
+			throw e;
+		}
+	}
+
+	private Status32 getStatus32(MessageId m, ContactId c) throws SQLException {
+		PreparedStatement ps = null;
+		ResultSet rs = null;
+		try {
+			String sql = "SELECT groupId, timestamp, length, state,"
+					+ " groupShared, messageShared, deleted"
+					+ " FROM statuses"
+					+ " WHERE messageId = ? AND contactId = ?";
+			ps = connection.prepareStatement(sql);
+			ps.setBytes(1, m.getBytes());
+			ps.setInt(2, c.getInt());
+			rs = ps.executeQuery();
+			if (!rs.next()) throw new DbStateException();
+			GroupId groupId = new GroupId(rs.getBytes(1));
+			long timestamp = rs.getLong(2);
+			int length = rs.getInt(3);
+			State state = State.fromValue(rs.getInt(4));
+			boolean groupShared = rs.getBoolean(5);
+			boolean messageShared = rs.getBoolean(6);
+			boolean deleted = rs.getBoolean(7);
+			if (rs.next()) throw new DbStateException();
+			rs.close();
+			ps.close();
+			return new Status32(groupId, timestamp, length, state,
+					groupShared, messageShared, deleted);
+		} catch (SQLException e) {
+			if (rs != null) rs.close();
+			if (ps != null) ps.close();
+			throw e;
+		}
+	}
+
+	private static class Status32 {
+
+		private final GroupId groupId;
+		private final long timestamp;
+		private final int length;
+		private final State state;
+		private final boolean groupShared, messageShared, deleted;
+
+		private Status32(GroupId groupId, long timestamp, int length,
+				State state, boolean groupShared, boolean messageShared,
+				boolean deleted) {
+			this.groupId = groupId;
+			this.timestamp = timestamp;
+			this.length = length;
+			this.state = state;
+			this.groupShared = groupShared;
+			this.messageShared = messageShared;
+			this.deleted = deleted;
+		}
+	}
+}

bramble-core/src/test/java/org/briarproject/bramble/plugin/PollerTest.java

@@ -12,14 +12,14 @@ import org.briarproject.bramble.api.plugin.duplex.DuplexPlugin;
 import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
 import org.briarproject.bramble.api.plugin.event.ConnectionClosedEvent;
 import org.briarproject.bramble.api.plugin.event.ConnectionOpenedEvent;
+import org.briarproject.bramble.api.plugin.event.TransportDisabledEvent;
 import org.briarproject.bramble.api.plugin.event.TransportEnabledEvent;
 import org.briarproject.bramble.api.plugin.simplex.SimplexPlugin;
 import org.briarproject.bramble.api.system.Clock;
-import org.briarproject.bramble.test.BrambleTestCase;
+import org.briarproject.bramble.test.BrambleMockTestCase;
 import org.briarproject.bramble.test.ImmediateExecutor;
 import org.briarproject.bramble.test.RunAction;
 import org.jmock.Expectations;
-import org.jmock.Mockery;
 import org.jmock.lib.legacy.ClassImposteriser;
 import org.junit.Test;
 
@@ -29,30 +29,37 @@ import java.util.Collections;
 import java.util.List;
 import java.util.concurrent.Executor;
 import java.util.concurrent.ScheduledExecutorService;
+import java.util.concurrent.ScheduledFuture;
 
 import static java.util.concurrent.TimeUnit.MILLISECONDS;
 
-public class PollerTest extends BrambleTestCase {
+public class PollerTest extends BrambleMockTestCase {
 
+	private final ScheduledExecutorService scheduler =
+			context.mock(ScheduledExecutorService.class);
+	private final ConnectionManager connectionManager =
+			context.mock(ConnectionManager.class);
+	private final ConnectionRegistry connectionRegistry =
+			context.mock(ConnectionRegistry.class);
+	private final PluginManager pluginManager =
+			context.mock(PluginManager.class);
+	private final Clock clock = context.mock(Clock.class);
+	private final ScheduledFuture future = context.mock(ScheduledFuture.class);
+	private final SecureRandom random;
+
+	private final Executor ioExecutor = new ImmediateExecutor();
+	private final TransportId transportId = new TransportId("id");
 	private final ContactId contactId = new ContactId(234);
 	private final int pollingInterval = 60 * 1000;
 	private final long now = System.currentTimeMillis();
 
+	public PollerTest() {
+		context.setImposteriser(ClassImposteriser.INSTANCE);
+		random = context.mock(SecureRandom.class);
+	}
+
 	@Test
 	public void testConnectOnContactStatusChanged() throws Exception {
-		Mockery context = new Mockery();
-		context.setImposteriser(ClassImposteriser.INSTANCE);
-		Executor ioExecutor = new ImmediateExecutor();
-		ScheduledExecutorService scheduler =
-				context.mock(ScheduledExecutorService.class);
-		ConnectionManager connectionManager =
-				context.mock(ConnectionManager.class);
-		ConnectionRegistry connectionRegistry =
-				context.mock(ConnectionRegistry.class);
-		PluginManager pluginManager = context.mock(PluginManager.class);
-		SecureRandom random = context.mock(SecureRandom.class);
-		Clock clock = context.mock(Clock.class);
-
 		// Two simplex plugins: one supports polling, the other doesn't
 		SimplexPlugin simplexPlugin = context.mock(SimplexPlugin.class);
 		SimplexPlugin simplexPlugin1 =
@@ -120,28 +127,12 @@ public class PollerTest extends BrambleTestCase {
 				connectionRegistry, pluginManager, random, clock);
 
 		p.eventOccurred(new ContactStatusChangedEvent(contactId, true));
-
-		context.assertIsSatisfied();
 	}
 
 	@Test
 	public void testRescheduleAndReconnectOnConnectionClosed()
 			throws Exception {
-		Mockery context = new Mockery();
-		context.setImposteriser(ClassImposteriser.INSTANCE);
-		Executor ioExecutor = new ImmediateExecutor();
-		ScheduledExecutorService scheduler =
-				context.mock(ScheduledExecutorService.class);
-		ConnectionManager connectionManager =
-				context.mock(ConnectionManager.class);
-		ConnectionRegistry connectionRegistry =
-				context.mock(ConnectionRegistry.class);
-		PluginManager pluginManager = context.mock(PluginManager.class);
-		SecureRandom random = context.mock(SecureRandom.class);
-		Clock clock = context.mock(Clock.class);
-
 		DuplexPlugin plugin = context.mock(DuplexPlugin.class);
-		TransportId transportId = new TransportId("id");
 		DuplexTransportConnection duplexConnection =
 				context.mock(DuplexTransportConnection.class);
 
@@ -168,6 +159,7 @@ public class PollerTest extends BrambleTestCase {
 			will(returnValue(now));
 			oneOf(scheduler).schedule(with(any(Runnable.class)),
 					with((long) pollingInterval), with(MILLISECONDS));
+			will(returnValue(future));
 			// connectToContact()
 			// Check whether the contact is already connected
 			oneOf(connectionRegistry).isConnected(contactId, transportId);
@@ -185,28 +177,12 @@ public class PollerTest extends BrambleTestCase {
 
 		p.eventOccurred(new ConnectionClosedEvent(contactId, transportId,
 				false));
-
-		context.assertIsSatisfied();
 	}
 
 
 	@Test
 	public void testRescheduleOnConnectionOpened() throws Exception {
-		Mockery context = new Mockery();
-		context.setImposteriser(ClassImposteriser.INSTANCE);
-		Executor ioExecutor = new ImmediateExecutor();
-		ScheduledExecutorService scheduler =
-				context.mock(ScheduledExecutorService.class);
-		ConnectionManager connectionManager =
-				context.mock(ConnectionManager.class);
-		ConnectionRegistry connectionRegistry =
-				context.mock(ConnectionRegistry.class);
-		PluginManager pluginManager = context.mock(PluginManager.class);
-		SecureRandom random = context.mock(SecureRandom.class);
-		Clock clock = context.mock(Clock.class);
-
-		DuplexPlugin plugin = context.mock(DuplexPlugin.class);
-		TransportId transportId = new TransportId("id");
+		Plugin plugin = context.mock(Plugin.class);
 
 		context.checking(new Expectations() {{
 			allowing(plugin).getId();
@@ -224,6 +200,7 @@ public class PollerTest extends BrambleTestCase {
 			will(returnValue(now));
 			oneOf(scheduler).schedule(with(any(Runnable.class)),
 					with((long) pollingInterval), with(MILLISECONDS));
+			will(returnValue(future));
 		}});
 
 		Poller p = new Poller(ioExecutor, scheduler, connectionManager,
@@ -231,27 +208,11 @@ public class PollerTest extends BrambleTestCase {
 
 		p.eventOccurred(new ConnectionOpenedEvent(contactId, transportId,
 				false));
-
-		context.assertIsSatisfied();
 	}
 
 	@Test
 	public void testRescheduleDoesNotReplaceEarlierTask() throws Exception {
-		Mockery context = new Mockery();
-		context.setImposteriser(ClassImposteriser.INSTANCE);
-		Executor ioExecutor = new ImmediateExecutor();
-		ScheduledExecutorService scheduler =
-				context.mock(ScheduledExecutorService.class);
-		ConnectionManager connectionManager =
-				context.mock(ConnectionManager.class);
-		ConnectionRegistry connectionRegistry =
-				context.mock(ConnectionRegistry.class);
-		PluginManager pluginManager = context.mock(PluginManager.class);
-		SecureRandom random = context.mock(SecureRandom.class);
-		Clock clock = context.mock(Clock.class);
-
-		DuplexPlugin plugin = context.mock(DuplexPlugin.class);
-		TransportId transportId = new TransportId("id");
+		Plugin plugin = context.mock(Plugin.class);
 
 		context.checking(new Expectations() {{
 			allowing(plugin).getId();
@@ -270,6 +231,7 @@ public class PollerTest extends BrambleTestCase {
 			will(returnValue(now));
 			oneOf(scheduler).schedule(with(any(Runnable.class)),
 					with((long) pollingInterval), with(MILLISECONDS));
+			will(returnValue(future));
 			// Second event
 			// Get the plugin
 			oneOf(pluginManager).getPlugin(transportId);
@@ -291,27 +253,59 @@ public class PollerTest extends BrambleTestCase {
 				false));
 		p.eventOccurred(new ConnectionOpenedEvent(contactId, transportId,
 				false));
-
-		context.assertIsSatisfied();
 	}
 
 	@Test
-	public void testPollOnTransportEnabled() throws Exception {
-		Mockery context = new Mockery();
-		context.setImposteriser(ClassImposteriser.INSTANCE);
-		Executor ioExecutor = new ImmediateExecutor();
-		ScheduledExecutorService scheduler =
-				context.mock(ScheduledExecutorService.class);
-		ConnectionManager connectionManager =
-				context.mock(ConnectionManager.class);
-		ConnectionRegistry connectionRegistry =
-				context.mock(ConnectionRegistry.class);
-		PluginManager pluginManager = context.mock(PluginManager.class);
-		SecureRandom random = context.mock(SecureRandom.class);
-		Clock clock = context.mock(Clock.class);
-
+	public void testRescheduleReplacesLaterTask() throws Exception {
+		Plugin plugin = context.mock(Plugin.class);
+
+		context.checking(new Expectations() {{
+			allowing(plugin).getId();
+			will(returnValue(transportId));
+			// First event
+			// Get the plugin
+			oneOf(pluginManager).getPlugin(transportId);
+			will(returnValue(plugin));
+			// The plugin supports polling
+			oneOf(plugin).shouldPoll();
+			will(returnValue(true));
+			// Schedule the next poll
+			oneOf(plugin).getPollingInterval();
+			will(returnValue(pollingInterval));
+			oneOf(clock).currentTimeMillis();
+			will(returnValue(now));
+			oneOf(scheduler).schedule(with(any(Runnable.class)),
+					with((long) pollingInterval), with(MILLISECONDS));
+			will(returnValue(future));
+			// Second event
+			// Get the plugin
+			oneOf(pluginManager).getPlugin(transportId);
+			will(returnValue(plugin));
+			// The plugin supports polling
+			oneOf(plugin).shouldPoll();
+			will(returnValue(true));
+			// Replace the previously scheduled task, due later
+			oneOf(plugin).getPollingInterval();
+			will(returnValue(pollingInterval - 2));
+			oneOf(clock).currentTimeMillis();
+			will(returnValue(now + 1));
+			oneOf(future).cancel(false);
+			oneOf(scheduler).schedule(with(any(Runnable.class)),
+					with((long) pollingInterval - 2), with(MILLISECONDS));
+		}});
+
+		Poller p = new Poller(ioExecutor, scheduler, connectionManager,
+				connectionRegistry, pluginManager, random, clock);
+
+		p.eventOccurred(new ConnectionOpenedEvent(contactId, transportId,
+				false));
+		p.eventOccurred(new ConnectionOpenedEvent(contactId, transportId,
+				false));
+	}
+
+	@Test
+	public void testPollsOnTransportEnabled() throws Exception {
 		Plugin plugin = context.mock(Plugin.class);
-		TransportId transportId = new TransportId("id");
 		List<ContactId> connected = Collections.singletonList(contactId);
 
 		context.checking(new Expectations() {{
@@ -328,6 +322,7 @@ public class PollerTest extends BrambleTestCase {
 			will(returnValue(now));
 			oneOf(scheduler).schedule(with(any(Runnable.class)), with(0L),
 					with(MILLISECONDS));
+			will(returnValue(future));
 			will(new RunAction());
 			// Running the polling task schedules the next polling task
 			oneOf(plugin).getPollingInterval();
@@ -338,6 +333,7 @@ public class PollerTest extends BrambleTestCase {
 			will(returnValue(now));
 			oneOf(scheduler).schedule(with(any(Runnable.class)),
 					with((long) (pollingInterval * 0.5)), with(MILLISECONDS));
+			will(returnValue(future));
 			// Poll the plugin
 			oneOf(connectionRegistry).getConnectedContacts(transportId);
 			will(returnValue(connected));
@@ -348,7 +344,36 @@ public class PollerTest extends BrambleTestCase {
 				connectionRegistry, pluginManager, random, clock);
 
 		p.eventOccurred(new TransportEnabledEvent(transportId));
+	}
 
-		context.assertIsSatisfied();
+	@Test
+	public void testCancelsPollingOnTransportDisabled() throws Exception {
+		Plugin plugin = context.mock(Plugin.class);
+		List<ContactId> connected = Collections.singletonList(contactId);
+
+		context.checking(new Expectations() {{
+			allowing(plugin).getId();
+			will(returnValue(transportId));
+			// Get the plugin
+			oneOf(pluginManager).getPlugin(transportId);
+			will(returnValue(plugin));
+			// The plugin supports polling
+			oneOf(plugin).shouldPoll();
+			will(returnValue(true));
+			// Schedule a polling task immediately
+			oneOf(clock).currentTimeMillis();
+			will(returnValue(now));
+			oneOf(scheduler).schedule(with(any(Runnable.class)), with(0L),
+					with(MILLISECONDS));
+			will(returnValue(future));
+			// The plugin is disabled before the task runs - cancel the task
+			oneOf(future).cancel(false);
+		}});
+
+		Poller p = new Poller(ioExecutor, scheduler, connectionManager,
+				connectionRegistry, pluginManager, random, clock);
+
+		p.eventOccurred(new TransportEnabledEvent(transportId));
+		p.eventOccurred(new TransportDisabledEvent(transportId));
 	}
 }

bramble-core/src/test/java/org/briarproject/bramble/plugin/tcp/LanTcpPluginTest.java

@@ -2,7 +2,6 @@ package org.briarproject.bramble.plugin.tcp;
 
 import org.briarproject.bramble.api.contact.ContactId;
 import org.briarproject.bramble.api.data.BdfList;
-import org.briarproject.bramble.api.keyagreement.KeyAgreementConnection;
 import org.briarproject.bramble.api.keyagreement.KeyAgreementListener;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.Backoff;
@@ -11,6 +10,7 @@ import org.briarproject.bramble.api.plugin.duplex.DuplexPluginCallback;
 import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
 import org.briarproject.bramble.api.properties.TransportProperties;
 import org.briarproject.bramble.api.settings.Settings;
+import org.briarproject.bramble.plugin.tcp.LanTcpPlugin.LanAddressComparator;
 import org.briarproject.bramble.test.BrambleTestCase;
 import org.junit.Test;
 
@@ -22,13 +22,12 @@ import java.net.NetworkInterface;
 import java.net.ServerSocket;
 import java.net.Socket;
 import java.util.Collections;
+import java.util.Comparator;
 import java.util.Hashtable;
 import java.util.Map;
-import java.util.concurrent.Callable;
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.Executor;
 import java.util.concurrent.Executors;
-import java.util.concurrent.FutureTask;
 import java.util.concurrent.atomic.AtomicBoolean;
 
 import static java.util.concurrent.TimeUnit.SECONDS;
@@ -56,6 +55,9 @@ public class LanTcpPluginTest extends BrambleTestCase {
 		// Local and remote in 192.168.0.0/16 should return true
 		assertTrue(plugin.addressesAreOnSameLan(makeAddress(192, 168, 0, 0),
 				makeAddress(192, 168, 255, 255)));
+		// Local and remote in 169.254.0.0/16 (link-local) should return true
+		assertTrue(plugin.addressesAreOnSameLan(makeAddress(169, 254, 0, 0),
+				makeAddress(169, 254, 255, 255)));
 		// Local and remote in different recognised prefixes should return false
 		assertFalse(plugin.addressesAreOnSameLan(makeAddress(10, 0, 0, 0),
 				makeAddress(172, 31, 255, 255)));
@@ -193,9 +195,16 @@ public class LanTcpPluginTest extends BrambleTestCase {
 		KeyAgreementListener kal =
 				plugin.createKeyAgreementListener(new byte[COMMIT_LENGTH]);
 		assertNotNull(kal);
-		Callable<KeyAgreementConnection> c = kal.listen();
-		FutureTask<KeyAgreementConnection> f = new FutureTask<>(c);
-		new Thread(f).start();
+		CountDownLatch latch = new CountDownLatch(1);
+		AtomicBoolean error = new AtomicBoolean(false);
+		new Thread(() -> {
+			try {
+				kal.accept();
+				latch.countDown();
+			} catch (IOException e) {
+				error.set(true);
+			}
+		}).start();
 		// The plugin should have bound a socket and stored the port number
 		BdfList descriptor = kal.getDescriptor();
 		assertEquals(3, descriptor.size());
@@ -211,10 +220,12 @@ public class LanTcpPluginTest extends BrambleTestCase {
 		InetSocketAddress socketAddr = new InetSocketAddress(addr, port);
 		Socket s = new Socket();
 		s.connect(socketAddr, 100);
-		assertNotNull(f.get(5, SECONDS));
+		// Check that the connection was accepted
+		assertTrue(latch.await(5, SECONDS));
+		assertFalse(error.get());
+		// Clean up
 		s.close();
 		kal.close();
-		// Stop the plugin
 		plugin.stop();
 	}
 
@@ -263,7 +274,7 @@ public class LanTcpPluginTest extends BrambleTestCase {
 		descriptor.add(local.getPort());
 		// Connect to the port
 		DuplexTransportConnection d = plugin.createKeyAgreementConnection(
-				new byte[COMMIT_LENGTH], descriptor, 5000);
+				new byte[COMMIT_LENGTH], descriptor);
 		assertNotNull(d);
 		// Check that the connection was accepted
 		assertTrue(latch.await(5, SECONDS));
@@ -275,6 +286,57 @@ public class LanTcpPluginTest extends BrambleTestCase {
 		plugin.stop();
 	}
 
+	@Test
+	public void testComparatorPrefersNonZeroPorts() throws Exception {
+		Comparator<InetSocketAddress> comparator = new LanAddressComparator();
+		InetSocketAddress nonZero = new InetSocketAddress("1.2.3.4", 1234);
+		InetSocketAddress zero = new InetSocketAddress("1.2.3.4", 0);
+
+		assertEquals(0, comparator.compare(nonZero, nonZero));
+		assertTrue(comparator.compare(nonZero, zero) < 0);
+
+		assertTrue(comparator.compare(zero, nonZero) > 0);
+		assertEquals(0, comparator.compare(zero, zero));
+	}
+
+	@Test
+	public void testComparatorPrefersLongerPrefixes() throws Exception {
+		Comparator<InetSocketAddress> comparator = new LanAddressComparator();
+		InetSocketAddress prefix192 = new InetSocketAddress("192.168.0.1", 0);
+		InetSocketAddress prefix172 = new InetSocketAddress("172.16.0.1", 0);
+		InetSocketAddress prefix10 = new InetSocketAddress("10.0.0.1", 0);
+
+		assertEquals(0, comparator.compare(prefix192, prefix192));
+		assertTrue(comparator.compare(prefix192, prefix172) < 0);
+		assertTrue(comparator.compare(prefix192, prefix10) < 0);
+
+		assertTrue(comparator.compare(prefix172, prefix192) > 0);
+		assertEquals(0, comparator.compare(prefix172, prefix172));
+		assertTrue(comparator.compare(prefix172, prefix10) < 0);
+
+		assertTrue(comparator.compare(prefix10, prefix192) > 0);
+		assertTrue(comparator.compare(prefix10, prefix172) > 0);
+		assertEquals(0, comparator.compare(prefix10, prefix10));
+	}
+
+	@Test
+	public void testComparatorPrefersSiteLocalToLinkLocal() throws Exception {
+		Comparator<InetSocketAddress> comparator = new LanAddressComparator();
+		InetSocketAddress prefix192 = new InetSocketAddress("192.168.0.1", 0);
+		InetSocketAddress prefix172 = new InetSocketAddress("172.16.0.1", 0);
+		InetSocketAddress prefix10 = new InetSocketAddress("10.0.0.1", 0);
+		InetSocketAddress linkLocal = new InetSocketAddress("169.254.0.1", 0);
+
+		assertTrue(comparator.compare(prefix192, linkLocal) < 0);
+		assertTrue(comparator.compare(prefix172, linkLocal) < 0);
+		assertTrue(comparator.compare(prefix10, linkLocal) < 0);
+
+		assertTrue(comparator.compare(linkLocal, prefix192) > 0);
+		assertTrue(comparator.compare(linkLocal, prefix172) > 0);
+		assertTrue(comparator.compare(linkLocal, prefix10) > 0);
+		assertEquals(0, comparator.compare(linkLocal, linkLocal));
+	}
+
 	private boolean systemHasLocalIpv4Address() throws Exception {
 		for (NetworkInterface i : Collections.list(
 				NetworkInterface.getNetworkInterfaces())) {

bramble-core/src/test/java/org/briarproject/bramble/properties/TransportPropertyManagerImplTest.java

@@ -94,6 +94,8 @@ public class TransportPropertyManagerImplTest extends BrambleMockTestCase {
 		Group contactGroup1 = getGroup(), contactGroup2 = getGroup();
 
 		context.checking(new Expectations() {{
+			oneOf(db).containsGroup(txn, localGroup.getId());
+			will(returnValue(false));
 			oneOf(db).addGroup(txn, localGroup);
 			oneOf(db).getContacts(txn);
 			will(returnValue(contacts));
@@ -123,7 +125,21 @@ public class TransportPropertyManagerImplTest extends BrambleMockTestCase {
 	}
 
 	@Test
-	public void testCreatesGroupWhenAddingContact() throws Exception {
+	public void testDoesNotCreateGroupsAtStartupIfAlreadyCreated()
+			throws Exception {
+		Transaction txn = new Transaction(null, false);
+
+		context.checking(new Expectations() {{
+			oneOf(db).containsGroup(txn, localGroup.getId());
+			will(returnValue(true));
+		}});
+
+		TransportPropertyManagerImpl t = createInstance();
+		t.createLocalState(txn);
+	}
+
+	@Test
+	public void testCreatesContactGroupWhenAddingContact() throws Exception {
 		Transaction txn = new Transaction(null, false);
 		Contact contact = getContact(true);
 		Group contactGroup = getGroup();

bramble-core/src/test/java/org/briarproject/bramble/sync/ValidationManagerImplTest.java

@@ -100,21 +100,21 @@ public class ValidationManagerImplTest extends BrambleMockTestCase {
 			// validateOutstandingMessages()
 			oneOf(db).startTransaction(true);
 			will(returnValue(txn));
-			oneOf(db).getMessagesToValidate(txn, clientId);
+			oneOf(db).getMessagesToValidate(txn);
 			will(returnValue(Collections.emptyList()));
 			oneOf(db).commitTransaction(txn);
 			oneOf(db).endTransaction(txn);
 			// deliverOutstandingMessages()
 			oneOf(db).startTransaction(true);
 			will(returnValue(txn1));
-			oneOf(db).getPendingMessages(txn1, clientId);
+			oneOf(db).getPendingMessages(txn1);
 			will(returnValue(Collections.emptyList()));
 			oneOf(db).commitTransaction(txn1);
 			oneOf(db).endTransaction(txn1);
 			// shareOutstandingMessages()
 			oneOf(db).startTransaction(true);
 			will(returnValue(txn2));
-			oneOf(db).getMessagesToShare(txn2, clientId);
+			oneOf(db).getMessagesToShare(txn2);
 			will(returnValue(Collections.emptyList()));
 			oneOf(db).commitTransaction(txn2);
 			oneOf(db).endTransaction(txn2);
@@ -138,7 +138,7 @@ public class ValidationManagerImplTest extends BrambleMockTestCase {
 			// Get messages to validate
 			oneOf(db).startTransaction(true);
 			will(returnValue(txn));
-			oneOf(db).getMessagesToValidate(txn, clientId);
+			oneOf(db).getMessagesToValidate(txn);
 			will(returnValue(Arrays.asList(messageId, messageId1)));
 			oneOf(db).commitTransaction(txn);
 			oneOf(db).endTransaction(txn);
@@ -199,14 +199,14 @@ public class ValidationManagerImplTest extends BrambleMockTestCase {
 			// Get pending messages to deliver
 			oneOf(db).startTransaction(true);
 			will(returnValue(txn5));
-			oneOf(db).getPendingMessages(txn5, clientId);
+			oneOf(db).getPendingMessages(txn5);
 			will(returnValue(Collections.emptyList()));
 			oneOf(db).commitTransaction(txn5);
 			oneOf(db).endTransaction(txn5);
 			// Get messages to share
 			oneOf(db).startTransaction(true);
 			will(returnValue(txn6));
-			oneOf(db).getMessagesToShare(txn6, clientId);
+			oneOf(db).getMessagesToShare(txn6);
 			will(returnValue(Collections.emptyList()));
 			oneOf(db).commitTransaction(txn6);
 			oneOf(db).endTransaction(txn6);
@@ -227,14 +227,14 @@ public class ValidationManagerImplTest extends BrambleMockTestCase {
 			// Get messages to validate
 			oneOf(db).startTransaction(true);
 			will(returnValue(txn));
-			oneOf(db).getMessagesToValidate(txn, clientId);
+			oneOf(db).getMessagesToValidate(txn);
 			will(returnValue(Collections.emptyList()));
 			oneOf(db).commitTransaction(txn);
 			oneOf(db).endTransaction(txn);
 			// Get pending messages to deliver
 			oneOf(db).startTransaction(true);
 			will(returnValue(txn1));
-			oneOf(db).getPendingMessages(txn1, clientId);
+			oneOf(db).getPendingMessages(txn1);
 			will(returnValue(Collections.singletonList(messageId)));
 			oneOf(db).commitTransaction(txn1);
 			oneOf(db).endTransaction(txn1);
@@ -292,7 +292,7 @@ public class ValidationManagerImplTest extends BrambleMockTestCase {
 			// Get messages to share
 			oneOf(db).startTransaction(true);
 			will(returnValue(txn4));
-			oneOf(db).getMessagesToShare(txn4, clientId);
+			oneOf(db).getMessagesToShare(txn4);
 			will(returnValue(Collections.emptyList()));
 			oneOf(db).commitTransaction(txn4);
 			oneOf(db).endTransaction(txn4);
@@ -313,14 +313,14 @@ public class ValidationManagerImplTest extends BrambleMockTestCase {
 			// No messages to validate
 			oneOf(db).startTransaction(true);
 			will(returnValue(txn));
-			oneOf(db).getMessagesToValidate(txn, clientId);
+			oneOf(db).getMessagesToValidate(txn);
 			will(returnValue(Collections.emptyList()));
 			oneOf(db).commitTransaction(txn);
 			oneOf(db).endTransaction(txn);
 			// No pending messages to deliver
 			oneOf(db).startTransaction(true);
 			will(returnValue(txn1));
-			oneOf(db).getPendingMessages(txn1, clientId);
+			oneOf(db).getPendingMessages(txn1);
 			will(returnValue(Collections.emptyList()));
 			oneOf(db).commitTransaction(txn1);
 			oneOf(db).endTransaction(txn1);
@@ -328,7 +328,7 @@ public class ValidationManagerImplTest extends BrambleMockTestCase {
 			// Get messages to share
 			oneOf(db).startTransaction(true);
 			will(returnValue(txn2));
-			oneOf(db).getMessagesToShare(txn2, clientId);
+			oneOf(db).getMessagesToShare(txn2);
 			will(returnValue(Collections.singletonList(messageId)));
 			oneOf(db).commitTransaction(txn2);
 			oneOf(db).endTransaction(txn2);
@@ -416,7 +416,7 @@ public class ValidationManagerImplTest extends BrambleMockTestCase {
 			// Get messages to validate
 			oneOf(db).startTransaction(true);
 			will(returnValue(txn));
-			oneOf(db).getMessagesToValidate(txn, clientId);
+			oneOf(db).getMessagesToValidate(txn);
 			will(returnValue(Arrays.asList(messageId, messageId1)));
 			oneOf(db).commitTransaction(txn);
 			oneOf(db).endTransaction(txn);
@@ -457,14 +457,14 @@ public class ValidationManagerImplTest extends BrambleMockTestCase {
 			// Get pending messages to deliver
 			oneOf(db).startTransaction(true);
 			will(returnValue(txn4));
-			oneOf(db).getPendingMessages(txn4, clientId);
+			oneOf(db).getPendingMessages(txn4);
 			will(returnValue(Collections.emptyList()));
 			oneOf(db).commitTransaction(txn4);
 			oneOf(db).endTransaction(txn4);
 			// Get messages to share
 			oneOf(db).startTransaction(true);
 			will(returnValue(txn5));
-			oneOf(db).getMessagesToShare(txn5, clientId);
+			oneOf(db).getMessagesToShare(txn5);
 			will(returnValue(Collections.emptyList()));
 			oneOf(db).commitTransaction(txn5);
 			oneOf(db).endTransaction(txn5);
@@ -487,7 +487,7 @@ public class ValidationManagerImplTest extends BrambleMockTestCase {
 			// Get messages to validate
 			oneOf(db).startTransaction(true);
 			will(returnValue(txn));
-			oneOf(db).getMessagesToValidate(txn, clientId);
+			oneOf(db).getMessagesToValidate(txn);
 			will(returnValue(Arrays.asList(messageId, messageId1)));
 			oneOf(db).commitTransaction(txn);
 			oneOf(db).endTransaction(txn);
@@ -533,14 +533,14 @@ public class ValidationManagerImplTest extends BrambleMockTestCase {
 			// Get pending messages to deliver
 			oneOf(db).startTransaction(true);
 			will(returnValue(txn4));
-			oneOf(db).getPendingMessages(txn4, clientId);
+			oneOf(db).getPendingMessages(txn4);
 			will(returnValue(Collections.emptyList()));
 			oneOf(db).commitTransaction(txn4);
 			oneOf(db).endTransaction(txn4);
 			// Get messages to share
 			oneOf(db).startTransaction(true);
 			will(returnValue(txn5));
-			oneOf(db).getMessagesToShare(txn5, clientId);
+			oneOf(db).getMessagesToShare(txn5);
 			will(returnValue(Collections.emptyList()));
 			oneOf(db).commitTransaction(txn5);
 			oneOf(db).endTransaction(txn5);

bramble-core/src/test/java/org/briarproject/bramble/test/TestLifecycleModule.java

@@ -17,6 +17,8 @@ import javax.inject.Singleton;
 import dagger.Module;
 import dagger.Provides;
 
+import static org.briarproject.bramble.api.lifecycle.LifecycleManager.LifecycleState.RUNNING;
+
 @Module
 public class TestLifecycleModule {
 
@@ -57,6 +59,11 @@ public class TestLifecycleModule {
 			@Override
 			public void waitForShutdown() throws InterruptedException {
 			}
+
+			@Override
+			public LifecycleState getLifecycleState() {
+				return RUNNING;
+			}
 		};
 		return lifecycleManager;
 	}

bramble-j2se/src/main/java/org/briarproject/bramble/plugin/DesktopPluginModule.java

@@ -1,5 +1,6 @@
 package org.briarproject.bramble.plugin;
 
+import org.briarproject.bramble.api.event.EventBus;
 import org.briarproject.bramble.api.lifecycle.IoExecutor;
 import org.briarproject.bramble.api.lifecycle.ShutdownManager;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
@@ -8,7 +9,7 @@ import org.briarproject.bramble.api.plugin.PluginConfig;
 import org.briarproject.bramble.api.plugin.duplex.DuplexPluginFactory;
 import org.briarproject.bramble.api.plugin.simplex.SimplexPluginFactory;
 import org.briarproject.bramble.api.reliability.ReliabilityLayerFactory;
-import org.briarproject.bramble.plugin.bluetooth.BluetoothPluginFactory;
+import org.briarproject.bramble.plugin.bluetooth.JavaBluetoothPluginFactory;
 import org.briarproject.bramble.plugin.file.RemovableDrivePluginFactory;
 import org.briarproject.bramble.plugin.modem.ModemPluginFactory;
 import org.briarproject.bramble.plugin.tcp.LanTcpPluginFactory;
@@ -30,9 +31,10 @@ public class DesktopPluginModule extends PluginModule {
 	PluginConfig getPluginConfig(@IoExecutor Executor ioExecutor,
 			SecureRandom random, BackoffFactory backoffFactory,
 			ReliabilityLayerFactory reliabilityFactory,
-			ShutdownManager shutdownManager) {
-		DuplexPluginFactory bluetooth = new BluetoothPluginFactory(ioExecutor,
-				random, backoffFactory);
+			ShutdownManager shutdownManager, EventBus eventBus) {
+		DuplexPluginFactory bluetooth =
+				new JavaBluetoothPluginFactory(ioExecutor, random, eventBus,
+						backoffFactory);
 		DuplexPluginFactory modem = new ModemPluginFactory(ioExecutor,
 				reliabilityFactory);
 		DuplexPluginFactory lan = new LanTcpPluginFactory(ioExecutor,

bramble-j2se/src/main/java/org/briarproject/bramble/plugin/bluetooth/JavaBluetoothPlugin.java

@@ -0,0 +1,115 @@
+package org.briarproject.bramble.plugin.bluetooth;
+
+import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
+import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
+import org.briarproject.bramble.api.plugin.Backoff;
+import org.briarproject.bramble.api.plugin.duplex.DuplexPluginCallback;
+import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
+
+import java.io.IOException;
+import java.security.SecureRandom;
+import java.util.concurrent.Executor;
+import java.util.logging.Logger;
+
+import javax.annotation.Nullable;
+import javax.bluetooth.BluetoothStateException;
+import javax.bluetooth.LocalDevice;
+import javax.microedition.io.Connector;
+import javax.microedition.io.StreamConnection;
+import javax.microedition.io.StreamConnectionNotifier;
+
+import static java.util.logging.Level.WARNING;
+import static org.briarproject.bramble.util.StringUtils.isValidMac;
+
+@MethodsNotNullByDefault
+@ParametersNotNullByDefault
+class JavaBluetoothPlugin extends BluetoothPlugin<StreamConnectionNotifier> {
+
+	private static final Logger LOG =
+			Logger.getLogger(JavaBluetoothPlugin.class.getName());
+
+	// Non-null if the plugin started successfully
+	private volatile LocalDevice localDevice = null;
+
+	JavaBluetoothPlugin(Executor ioExecutor, SecureRandom secureRandom,
+			Backoff backoff, DuplexPluginCallback callback, int maxLatency) {
+		super(ioExecutor, secureRandom, backoff, callback, maxLatency);
+	}
+
+	@Override
+	void initialiseAdapter() throws IOException {
+		try {
+			localDevice = LocalDevice.getLocalDevice();
+		} catch (UnsatisfiedLinkError | BluetoothStateException e) {
+			throw new IOException(e);
+		}
+	}
+
+	@Override
+	boolean isAdapterEnabled() {
+		return localDevice != null && LocalDevice.isPowerOn();
+	}
+
+	@Override
+	void enableAdapter() {
+		// Nothing we can do on this platform
+		LOG.info("Could not enable Bluetooth");
+	}
+
+	@Override
+	void disableAdapterIfEnabledByUs() {
+		// We didn't enable it so we don't need to disable it
+	}
+
+	@Override
+	void setEnabledByUs() {
+		// Irrelevant on this platform
+	}
+
+	@Nullable
+	@Override
+	String getBluetoothAddress() {
+		return localDevice.getBluetoothAddress();
+	}
+
+	@Override
+	StreamConnectionNotifier openServerSocket(String uuid) throws IOException {
+		String url = makeUrl("localhost", uuid);
+		return (StreamConnectionNotifier) Connector.open(url);
+	}
+
+	@Override
+	void tryToClose(@Nullable StreamConnectionNotifier ss) {
+		try {
+			if (ss != null) ss.close();
+		} catch (IOException e) {
+			if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
+		}
+	}
+
+	@Override
+	DuplexTransportConnection acceptConnection(StreamConnectionNotifier ss)
+			throws IOException {
+		return wrapSocket(ss.acceptAndOpen());
+	}
+
+	@Override
+	boolean isValidAddress(String address) {
+		return isValidMac(address);
+	}
+
+	@Override
+	DuplexTransportConnection connectTo(String address, String uuid)
+			throws IOException {
+		String url = makeUrl(address, uuid);
+		return wrapSocket((StreamConnection) Connector.open(url));
+	}
+
+	private String makeUrl(String address, String uuid) {
+		return "btspp://" + address + ":" + uuid + ";name=RFCOMM";
+	}
+
+	private DuplexTransportConnection wrapSocket(StreamConnection s) {
+		return new JavaBluetoothTransportConnection(this, s);
+	}
+}

bramble-j2se/src/main/java/org/briarproject/bramble/plugin/bluetooth/JavaBluetoothPluginFactory.java

@@ -1,5 +1,6 @@
 package org.briarproject.bramble.plugin.bluetooth;
 
+import org.briarproject.bramble.api.event.EventBus;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.Backoff;
 import org.briarproject.bramble.api.plugin.BackoffFactory;
@@ -17,7 +18,7 @@ import static org.briarproject.bramble.api.plugin.BluetoothConstants.ID;
 
 @Immutable
 @NotNullByDefault
-public class BluetoothPluginFactory implements DuplexPluginFactory {
+public class JavaBluetoothPluginFactory implements DuplexPluginFactory {
 
 	private static final int MAX_LATENCY = 30 * 1000; // 30 seconds
 	private static final int MIN_POLLING_INTERVAL = 60 * 1000; // 1 minute
@@ -27,12 +28,15 @@ public class BluetoothPluginFactory implements DuplexPluginFactory {
 	private final Executor ioExecutor;
 	private final SecureRandom secureRandom;
 	private final BackoffFactory backoffFactory;
+	private final EventBus eventBus;
 
-	public BluetoothPluginFactory(Executor ioExecutor,
-			SecureRandom secureRandom, BackoffFactory backoffFactory) {
+	public JavaBluetoothPluginFactory(Executor ioExecutor,
+			SecureRandom secureRandom, EventBus eventBus,
+			BackoffFactory backoffFactory) {
 		this.ioExecutor = ioExecutor;
 		this.secureRandom = secureRandom;
 		this.backoffFactory = backoffFactory;
+		this.eventBus = eventBus;
 	}
 
 	@Override
@@ -49,7 +53,9 @@ public class BluetoothPluginFactory implements DuplexPluginFactory {
 	public DuplexPlugin createPlugin(DuplexPluginCallback callback) {
 		Backoff backoff = backoffFactory.createBackoff(MIN_POLLING_INTERVAL,
 				MAX_POLLING_INTERVAL, BACKOFF_BASE);
-		return new BluetoothPlugin(ioExecutor, secureRandom, backoff, callback,
-				MAX_LATENCY);
+		JavaBluetoothPlugin plugin = new JavaBluetoothPlugin(ioExecutor,
+				secureRandom, backoff, callback, MAX_LATENCY);
+		eventBus.addListener(plugin);
+		return plugin;
 	}
 }

bramble-j2se/src/main/java/org/briarproject/bramble/plugin/bluetooth/JavaBluetoothTransportConnection.java

@@ -11,11 +11,12 @@ import java.io.OutputStream;
 import javax.microedition.io.StreamConnection;
 
 @NotNullByDefault
-class BluetoothTransportConnection extends AbstractDuplexTransportConnection {
+class JavaBluetoothTransportConnection
+		extends AbstractDuplexTransportConnection {
 
 	private final StreamConnection stream;
 
-	BluetoothTransportConnection(Plugin plugin, StreamConnection stream) {
+	JavaBluetoothTransportConnection(Plugin plugin, StreamConnection stream) {
 		super(plugin);
 		this.stream = stream;
 	}

bramble-j2se/src/main/java/org/briarproject/bramble/plugin/modem/ModemPlugin.java

@@ -177,7 +177,7 @@ class ModemPlugin implements DuplexPlugin, Modem.Callback {
 
 	@Override
 	public DuplexTransportConnection createKeyAgreementConnection(
-			byte[] commitment, BdfList descriptor, long timeout) {
+			byte[] commitment, BdfList descriptor) {
 		throw new UnsupportedOperationException();
 	}
 

briar-android/.tx/config

@@ -1,6 +1,6 @@
 [main]
 host = https://www.transifex.com
-lang_map = pt_BR: pt-rBR, fr_FR: fr, nb_NO: nb, zh-Hans: zh-rCN
+lang_map = pt_BR: pt-rBR, nb_NO: nb, zh-Hans: zh-rCN
 
 [briar.stringsxml-5]
 file_filter = src/main/res/values-<lang>/strings.xml

briar-android/build.gradle

@@ -1,6 +1,10 @@
 apply plugin: 'com.android.application'
 apply plugin: 'witness'
 
+configurations.all {
+	resolutionStrategy.preferProjectModules()
+}
+
 dependencies {
 	implementation project(path: ':briar-core', configuration: 'default')
 	implementation project(path: ':bramble-core', configuration: 'default')
@@ -20,7 +24,7 @@ dependencies {
 	}
 	implementation "com.android.support:cardview-v7:$supportVersion"
 	implementation "com.android.support:support-annotations:$supportVersion"
-	implementation 'com.android.support.constraint:constraint-layout:1.0.2'
+	implementation 'com.android.support.constraint:constraint-layout:1.1.0-beta3'
 
 	implementation('ch.acra:acra:4.8.5') {
 		exclude module: 'support-v4'
@@ -61,8 +65,8 @@ dependencyVerification {
 			'ch.acra:acra:4.8.5:acra-4.8.5.aar:afd5b28934d5166b55f261c85685ad59e8a4ebe9ca1960906afaa8c76d8dc9eb',
 			'classworlds:classworlds:1.1-alpha-2:classworlds-1.1-alpha-2.jar:2bf4e59f3acd106fea6145a9a88fe8956509f8b9c0fdd11eb96fee757269e3f3',
 			'com.almworks.sqlite4java:sqlite4java:0.282:sqlite4java-0.282.jar:9e1d8dd83ca6003f841e3af878ce2dc7c22497493a7bb6d1b62ec1b0d0a83c05',
-			'com.android.support.constraint:constraint-layout-solver:1.0.2:constraint-layout-solver-1.0.2.jar:8c62525a9bc5cff5633a96cb9b32fffeccaf41b8841aa87fc22607070dea9b8d',
-			'com.android.support.constraint:constraint-layout:1.0.2:constraint-layout-1.0.2.aar:b0c688cc2b7172608f8153a689d746da40f71e52d7e2fe2bfd9df2f92db77085',
+			'com.android.support.constraint:constraint-layout-solver:1.1.0-beta3:constraint-layout-solver-1.1.0-beta3.jar:c9084108415046c423983bdff8cf04c8e9a5bed41b8d5329f3764c08312ee3dd',
+			'com.android.support.constraint:constraint-layout:1.1.0-beta3:constraint-layout-1.1.0-beta3.aar:1754a6bd135feae485aa2ebf9e170f0f3d3282b392f8aa3067d0ed668839db79',
 			'com.android.support:animated-vector-drawable:27.0.1:animated-vector-drawable-27.0.1.aar:365050110411c86c7eec86101b49ab53557ffe6667f60b19055f1d35c38a577b',
 			'com.android.support:appcompat-v7:27.0.1:appcompat-v7-27.0.1.aar:1402c29a49db30346c21a7d40634461765b3ab826f5dd95bc4dcc76787b21851',
 			'com.android.support:cardview-v7:27.0.1:cardview-v7-27.0.1.aar:43fccd44086c51eaa9d78be2fcf0dfea1556c8876a6fd325ea8d24e860054202',
@@ -169,7 +173,7 @@ def getGitHash = { ->
 	def stdout = new ByteArrayOutputStream()
 	try {
 		exec {
-			commandLine 'git', 'rev-parse', '--short', 'HEAD'
+			commandLine 'git', 'rev-parse', '--short=7', 'HEAD'
 			standardOutput = stdout
 		}
 		return stdout.toString().trim()
@@ -185,8 +189,8 @@ android {
 	defaultConfig {
 		minSdkVersion 14
 		targetSdkVersion 26
-		versionCode 1612
-		versionName "0.16.12"
+		versionCode 1620
+		versionName "0.16.20"
 		applicationId "org.briarproject.briar.beta"
 		resValue "string", "app_package", "org.briarproject.briar.beta"
 		resValue "string", "app_name", "Briar Beta"
@@ -197,7 +201,7 @@ android {
 		debug {
 			applicationIdSuffix ".debug"
 			resValue "string", "app_package", "org.briarproject.briar.beta.debug"
-			resValue "string", "app_name", "Briar Debug"
+			resValue "string", "app_name", "Briar Beta Debug"
 			shrinkResources false
 			minifyEnabled true
 			proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.txt'

briar-android/src/main/AndroidManifest.xml

@@ -77,6 +77,11 @@
 			</intent-filter>
 		</activity>
 
+		<activity
+			android:name=".android.login.OpenDatabaseActivity"
+			android:label="@string/app_name"
+			android:launchMode="singleTop"/>
+
 		<activity
 			android:name="org.briarproject.briar.android.navdrawer.NavDrawerActivity"
 			android:theme="@style/BriarTheme.NoActionBar"
@@ -369,7 +374,12 @@
 		</activity>
 
 		<activity
-			android:name="org.briarproject.briar.android.panic.ExitActivity"
+			android:name="org.briarproject.briar.android.logout.ExitActivity"
+			android:theme="@android:style/Theme.NoDisplay">
+		</activity>
+
+		<activity
+			android:name=".android.logout.HideUiActivity"
 			android:theme="@android:style/Theme.NoDisplay">
 		</activity>
 

briar-android/src/main/java/org/briarproject/briar/android/AndroidComponent.java

@@ -1,5 +1,7 @@
 package org.briarproject.briar.android;
 
+import android.content.SharedPreferences;
+
 import org.briarproject.bramble.BrambleAndroidModule;
 import org.briarproject.bramble.BrambleCoreEagerSingletons;
 import org.briarproject.bramble.BrambleCoreModule;
@@ -89,6 +91,8 @@ public interface AndroidComponent
 
 	AndroidNotificationManager androidNotificationManager();
 
+	SharedPreferences sharedPreferences();
+
 	ScreenFilterMonitor screenFilterMonitor();
 
 	ConnectionRegistry connectionRegistry();

briar-android/src/main/java/org/briarproject/briar/android/AndroidNotificationManagerImpl.java

@@ -1,13 +1,17 @@
 package org.briarproject.briar.android;
 
+import android.annotation.TargetApi;
 import android.app.Application;
+import android.app.NotificationChannel;
 import android.app.NotificationManager;
 import android.app.PendingIntent;
 import android.content.Context;
 import android.content.Intent;
 import android.net.Uri;
+import android.support.annotation.StringRes;
 import android.support.annotation.UiThread;
 import android.support.v4.app.TaskStackBuilder;
+import android.support.v4.content.ContextCompat;
 
 import org.briarproject.bramble.api.contact.ContactId;
 import org.briarproject.bramble.api.db.DatabaseExecutor;
@@ -44,6 +48,7 @@ import org.briarproject.briar.api.sharing.event.InvitationResponseReceivedEvent;
 
 import java.util.HashMap;
 import java.util.Map;
+import java.util.concurrent.Callable;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.Executor;
 import java.util.concurrent.Future;
@@ -57,8 +62,11 @@ import javax.inject.Inject;
 import static android.app.Notification.DEFAULT_LIGHTS;
 import static android.app.Notification.DEFAULT_SOUND;
 import static android.app.Notification.DEFAULT_VIBRATE;
+import static android.app.Notification.VISIBILITY_SECRET;
+import static android.app.NotificationManager.IMPORTANCE_DEFAULT;
 import static android.content.Context.NOTIFICATION_SERVICE;
 import static android.content.Intent.FLAG_ACTIVITY_CLEAR_TOP;
+import static android.os.Build.VERSION.SDK_INT;
 import static android.support.v4.app.NotificationCompat.CATEGORY_MESSAGE;
 import static android.support.v4.app.NotificationCompat.CATEGORY_SOCIAL;
 import static java.util.logging.Level.WARNING;
@@ -91,8 +99,9 @@ class AndroidNotificationManagerImpl implements AndroidNotificationManager,
 	private final Executor dbExecutor;
 	private final SettingsManager settingsManager;
 	private final AndroidExecutor androidExecutor;
-	private final Context appContext;
 	private final Clock clock;
+	private final Context appContext;
+	private final NotificationManager notificationManager;
 	private final AtomicBoolean used = new AtomicBoolean(false);
 
 	// The following must only be accessed on the main UI thread
@@ -121,6 +130,8 @@ class AndroidNotificationManagerImpl implements AndroidNotificationManager,
 		this.androidExecutor = androidExecutor;
 		this.clock = clock;
 		appContext = app.getApplicationContext();
+		notificationManager = (NotificationManager)
+				appContext.getSystemService(NOTIFICATION_SERVICE);
 	}
 
 	@Override
@@ -132,6 +143,39 @@ class AndroidNotificationManagerImpl implements AndroidNotificationManager,
 		} catch (DbException e) {
 			throw new ServiceException(e);
 		}
+		if (SDK_INT >= 26) {
+			// Create notification channels
+			Callable<Void> task = () -> {
+				createNotificationChannel(CONTACT_CHANNEL_ID,
+						R.string.contact_list_button);
+				createNotificationChannel(GROUP_CHANNEL_ID,
+						R.string.groups_button);
+				createNotificationChannel(FORUM_CHANNEL_ID,
+						R.string.forums_button);
+				createNotificationChannel(BLOG_CHANNEL_ID,
+						R.string.blogs_button);
+				return null;
+			};
+			try {
+				androidExecutor.runOnUiThread(task).get();
+			} catch (InterruptedException | ExecutionException e) {
+				throw new ServiceException(e);
+			}
+		}
+	}
+
+	@TargetApi(26)
+	private void createNotificationChannel(String channelId,
+			@StringRes int name) {
+		NotificationChannel nc =
+				new NotificationChannel(channelId, appContext.getString(name),
+						IMPORTANCE_DEFAULT);
+		nc.setLockscreenVisibility(VISIBILITY_SECRET);
+		nc.enableVibration(true);
+		nc.enableLights(true);
+		nc.setLightColor(
+				ContextCompat.getColor(appContext, R.color.briar_green_light));
+		notificationManager.createNotificationChannel(nc);
 	}
 
 	@Override
@@ -156,44 +200,34 @@ class AndroidNotificationManagerImpl implements AndroidNotificationManager,
 	private void clearContactNotification() {
 		contactCounts.clear();
 		contactTotal = 0;
-		Object o = appContext.getSystemService(NOTIFICATION_SERVICE);
-		NotificationManager nm = (NotificationManager) o;
-		nm.cancel(PRIVATE_MESSAGE_NOTIFICATION_ID);
+		notificationManager.cancel(PRIVATE_MESSAGE_NOTIFICATION_ID);
 	}
 
 	@UiThread
 	private void clearGroupMessageNotification() {
 		groupCounts.clear();
 		groupTotal = 0;
-		Object o = appContext.getSystemService(NOTIFICATION_SERVICE);
-		NotificationManager nm = (NotificationManager) o;
-		nm.cancel(GROUP_MESSAGE_NOTIFICATION_ID);
+		notificationManager.cancel(GROUP_MESSAGE_NOTIFICATION_ID);
 	}
 
 	@UiThread
 	private void clearForumPostNotification() {
 		forumCounts.clear();
 		forumTotal = 0;
-		Object o = appContext.getSystemService(NOTIFICATION_SERVICE);
-		NotificationManager nm = (NotificationManager) o;
-		nm.cancel(FORUM_POST_NOTIFICATION_ID);
+		notificationManager.cancel(FORUM_POST_NOTIFICATION_ID);
 	}
 
 	@UiThread
 	private void clearBlogPostNotification() {
 		blogCounts.clear();
 		blogTotal = 0;
-		Object o = appContext.getSystemService(NOTIFICATION_SERVICE);
-		NotificationManager nm = (NotificationManager) o;
-		nm.cancel(BLOG_POST_NOTIFICATION_ID);
+		notificationManager.cancel(BLOG_POST_NOTIFICATION_ID);
 	}
 
 	@UiThread
 	private void clearIntroductionSuccessNotification() {
 		introductionTotal = 0;
-		Object o = appContext.getSystemService(NOTIFICATION_SERVICE);
-		NotificationManager nm = (NotificationManager) o;
-		nm.cancel(INTRODUCTION_SUCCESS_NOTIFICATION_ID);
+		notificationManager.cancel(INTRODUCTION_SUCCESS_NOTIFICATION_ID);
 	}
 
 	@Override
@@ -269,8 +303,8 @@ class AndroidNotificationManagerImpl implements AndroidNotificationManager,
 		if (contactTotal == 0) {
 			clearContactNotification();
 		} else if (settings.getBoolean(PREF_NOTIFY_PRIVATE, true)) {
-			BriarNotificationBuilder b =
-					new BriarNotificationBuilder(appContext);
+			BriarNotificationBuilder b = new BriarNotificationBuilder(
+					appContext, CONTACT_CHANNEL_ID);
 			b.setSmallIcon(R.drawable.notification_private_message);
 			b.setColorRes(R.color.briar_primary);
 			b.setContentTitle(appContext.getText(R.string.app_name));
@@ -305,9 +339,8 @@ class AndroidNotificationManagerImpl implements AndroidNotificationManager,
 				t.addNextIntent(i);
 				b.setContentIntent(t.getPendingIntent(nextRequestId++, 0));
 			}
-			Object o = appContext.getSystemService(NOTIFICATION_SERVICE);
-			NotificationManager nm = (NotificationManager) o;
-			nm.notify(PRIVATE_MESSAGE_NOTIFICATION_ID, b.build());
+			notificationManager.notify(PRIVATE_MESSAGE_NOTIFICATION_ID,
+					b.build());
 		}
 	}
 
@@ -378,7 +411,7 @@ class AndroidNotificationManagerImpl implements AndroidNotificationManager,
 			clearGroupMessageNotification();
 		} else if (settings.getBoolean(PREF_NOTIFY_GROUP, true)) {
 			BriarNotificationBuilder b =
-					new BriarNotificationBuilder(appContext);
+					new BriarNotificationBuilder(appContext, GROUP_CHANNEL_ID);
 			b.setSmallIcon(R.drawable.notification_private_group);
 			b.setColorRes(R.color.briar_primary);
 			b.setContentTitle(appContext.getText(R.string.app_name));
@@ -414,9 +447,8 @@ class AndroidNotificationManagerImpl implements AndroidNotificationManager,
 				t.addNextIntent(i);
 				b.setContentIntent(t.getPendingIntent(nextRequestId++, 0));
 			}
-			Object o = appContext.getSystemService(NOTIFICATION_SERVICE);
-			NotificationManager nm = (NotificationManager) o;
-			nm.notify(GROUP_MESSAGE_NOTIFICATION_ID, b.build());
+			notificationManager.notify(GROUP_MESSAGE_NOTIFICATION_ID,
+					b.build());
 		}
 	}
 
@@ -455,7 +487,7 @@ class AndroidNotificationManagerImpl implements AndroidNotificationManager,
 			clearForumPostNotification();
 		} else if (settings.getBoolean(PREF_NOTIFY_FORUM, true)) {
 			BriarNotificationBuilder b =
-					new BriarNotificationBuilder(appContext);
+					new BriarNotificationBuilder(appContext, FORUM_CHANNEL_ID);
 			b.setSmallIcon(R.drawable.notification_forum);
 			b.setColorRes(R.color.briar_primary);
 			b.setContentTitle(appContext.getText(R.string.app_name));
@@ -491,9 +523,7 @@ class AndroidNotificationManagerImpl implements AndroidNotificationManager,
 				t.addNextIntent(i);
 				b.setContentIntent(t.getPendingIntent(nextRequestId++, 0));
 			}
-			Object o = appContext.getSystemService(NOTIFICATION_SERVICE);
-			NotificationManager nm = (NotificationManager) o;
-			nm.notify(FORUM_POST_NOTIFICATION_ID, b.build());
+			notificationManager.notify(FORUM_POST_NOTIFICATION_ID, b.build());
 		}
 	}
 
@@ -532,7 +562,7 @@ class AndroidNotificationManagerImpl implements AndroidNotificationManager,
 			clearBlogPostNotification();
 		} else if (settings.getBoolean(PREF_NOTIFY_BLOG, true)) {
 			BriarNotificationBuilder b =
-					new BriarNotificationBuilder(appContext);
+					new BriarNotificationBuilder(appContext, BLOG_CHANNEL_ID);
 			b.setSmallIcon(R.drawable.notification_blog);
 			b.setColorRes(R.color.briar_primary);
 			b.setContentTitle(appContext.getText(R.string.app_name));
@@ -555,9 +585,7 @@ class AndroidNotificationManagerImpl implements AndroidNotificationManager,
 			t.addNextIntent(i);
 			b.setContentIntent(t.getPendingIntent(nextRequestId++, 0));
 
-			Object o = appContext.getSystemService(NOTIFICATION_SERVICE);
-			NotificationManager nm = (NotificationManager) o;
-			nm.notify(BLOG_POST_NOTIFICATION_ID, b.build());
+			notificationManager.notify(BLOG_POST_NOTIFICATION_ID, b.build());
 		}
 	}
 
@@ -577,7 +605,8 @@ class AndroidNotificationManagerImpl implements AndroidNotificationManager,
 
 	@UiThread
 	private void updateIntroductionNotification() {
-		BriarNotificationBuilder b = new BriarNotificationBuilder(appContext);
+		BriarNotificationBuilder b =
+				new BriarNotificationBuilder(appContext, CONTACT_CHANNEL_ID);
 		b.setSmallIcon(R.drawable.notification_introduction);
 		b.setColorRes(R.color.briar_primary);
 		b.setContentTitle(appContext.getText(R.string.app_name));
@@ -599,9 +628,8 @@ class AndroidNotificationManagerImpl implements AndroidNotificationManager,
 		t.addNextIntent(i);
 		b.setContentIntent(t.getPendingIntent(nextRequestId++, 0));
 
-		Object o = appContext.getSystemService(NOTIFICATION_SERVICE);
-		NotificationManager nm = (NotificationManager) o;
-		nm.notify(INTRODUCTION_SUCCESS_NOTIFICATION_ID, b.build());
+		notificationManager.notify(INTRODUCTION_SUCCESS_NOTIFICATION_ID,
+				b.build());
 	}
 
 	@Override

briar-android/src/main/java/org/briarproject/briar/android/AppModule.java

@@ -1,6 +1,7 @@
 package org.briarproject.briar.android;
 
 import android.app.Application;
+import android.content.SharedPreferences;
 
 import org.briarproject.bramble.api.crypto.CryptoComponent;
 import org.briarproject.bramble.api.crypto.PublicKey;
@@ -93,6 +94,7 @@ public class AppModule {
 
 			@Override
 			public boolean databaseExists() {
+				// FIXME should not run on UiThread #620
 				if (!dir.isDirectory()) return false;
 				File[] files = dir.listFiles();
 				return files != null && files.length > 0;
@@ -157,6 +159,11 @@ public class AppModule {
 		return devConfig;
 	}
 
+	@Provides
+	SharedPreferences provideSharedPreferences(Application app) {
+		return app.getSharedPreferences("db", MODE_PRIVATE);
+	}
+
 	@Provides
 	@Singleton
 	ReferenceManager provideReferenceManager() {
@@ -174,8 +181,11 @@ public class AppModule {
 	}
 
 	@Provides
+	@Singleton
 	ScreenFilterMonitor provideScreenFilterMonitor(
+			LifecycleManager lifecycleManager,
 			ScreenFilterMonitorImpl screenFilterMonitor) {
+		lifecycleManager.registerService(screenFilterMonitor);
 		return screenFilterMonitor;
 	}
 

briar-android/src/main/java/org/briarproject/briar/android/BriarApplication.java

@@ -6,8 +6,8 @@ package org.briarproject.briar.android;
  */
 public interface BriarApplication {
 
-	// This build expires on 31 December 2017
-	long EXPIRY_DATE = 1514761200 * 1000L;
+	// This build expires on 30 April 2018
+	long EXPIRY_DATE = 1525046400 * 1000L;
 
 	AndroidComponent getApplicationComponent();
 

briar-android/src/main/java/org/briarproject/briar/android/BriarService.java

@@ -1,13 +1,16 @@
 package org.briarproject.briar.android;
 
+import android.app.NotificationChannel;
 import android.app.NotificationManager;
 import android.app.PendingIntent;
 import android.app.Service;
+import android.content.BroadcastReceiver;
 import android.content.ComponentName;
+import android.content.Context;
 import android.content.Intent;
+import android.content.IntentFilter;
 import android.content.ServiceConnection;
 import android.os.Binder;
-import android.os.Build;
 import android.os.IBinder;
 import android.support.v4.app.NotificationCompat;
 import android.support.v4.content.ContextCompat;
@@ -17,17 +20,27 @@ import org.briarproject.bramble.api.lifecycle.LifecycleManager;
 import org.briarproject.bramble.api.lifecycle.LifecycleManager.StartResult;
 import org.briarproject.bramble.api.system.AndroidExecutor;
 import org.briarproject.briar.R;
+import org.briarproject.briar.android.logout.HideUiActivity;
 import org.briarproject.briar.android.navdrawer.NavDrawerActivity;
+import org.briarproject.briar.android.splash.SplashScreenActivity;
 
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.logging.Logger;
 
+import javax.annotation.Nullable;
 import javax.inject.Inject;
 
+import static android.app.NotificationManager.IMPORTANCE_DEFAULT;
+import static android.app.NotificationManager.IMPORTANCE_NONE;
 import static android.app.PendingIntent.FLAG_UPDATE_CURRENT;
+import static android.content.Intent.ACTION_SHUTDOWN;
+import static android.content.Intent.FLAG_ACTIVITY_CLEAR_TASK;
 import static android.content.Intent.FLAG_ACTIVITY_CLEAR_TOP;
+import static android.content.Intent.FLAG_ACTIVITY_EXCLUDE_FROM_RECENTS;
 import static android.content.Intent.FLAG_ACTIVITY_NEW_TASK;
+import static android.content.Intent.FLAG_ACTIVITY_NO_ANIMATION;
+import static android.os.Build.VERSION.SDK_INT;
 import static android.support.v4.app.NotificationCompat.CATEGORY_SERVICE;
 import static android.support.v4.app.NotificationCompat.PRIORITY_MIN;
 import static android.support.v4.app.NotificationCompat.VISIBILITY_SECRET;
@@ -37,15 +50,30 @@ import static org.briarproject.bramble.api.lifecycle.LifecycleManager.StartResul
 
 public class BriarService extends Service {
 
+	public static String EXTRA_START_RESULT =
+			"org.briarproject.briar.START_RESULT";
+	public static String EXTRA_NOTIFICATION_ID =
+			"org.briarproject.briar.FAILURE_NOTIFICATION_ID";
+	public static String EXTRA_STARTUP_FAILED =
+			"org.briarproject.briar.STARTUP_FAILED";
+
 	private static final int ONGOING_NOTIFICATION_ID = 1;
 	private static final int FAILURE_NOTIFICATION_ID = 2;
 
+	// Channels are sorted by channel ID in the Settings app, so use IDs
+	// that will sort below the main channels such as contacts
+	private static final String ONGOING_CHANNEL_ID = "zForegroundService";
+	private static final String FAILURE_CHANNEL_ID = "zStartupFailure";
+
 	private static final Logger LOG =
 			Logger.getLogger(BriarService.class.getName());
 
 	private final AtomicBoolean created = new AtomicBoolean(false);
 	private final Binder binder = new BriarBinder();
 
+	@Nullable
+	private BroadcastReceiver receiver = null;
+
 	@Inject
 	protected DatabaseConfig databaseConfig;
 	// Fields that are accessed from background threads must be volatile
@@ -73,8 +101,27 @@ public class BriarService extends Service {
 			stopSelf();
 			return;
 		}
+
+		// Create notification channels
+		if (SDK_INT >= 26) {
+			NotificationManager nm = (NotificationManager)
+					getSystemService(NOTIFICATION_SERVICE);
+			NotificationChannel ongoingChannel = new NotificationChannel(
+					ONGOING_CHANNEL_ID,
+					getString(R.string.ongoing_notification_title),
+					IMPORTANCE_NONE);
+			ongoingChannel.setLockscreenVisibility(VISIBILITY_SECRET);
+			nm.createNotificationChannel(ongoingChannel);
+			NotificationChannel failureChannel = new NotificationChannel(
+					FAILURE_CHANNEL_ID,
+					getString(R.string.startup_failed_notification_title),
+					IMPORTANCE_DEFAULT);
+			failureChannel.setLockscreenVisibility(VISIBILITY_SECRET);
+			nm.createNotificationChannel(failureChannel);
+		}
 		// Show an ongoing notification that the service is running
-		NotificationCompat.Builder b = new NotificationCompat.Builder(this);
+		NotificationCompat.Builder b =
+				new NotificationCompat.Builder(this, ONGOING_CHANNEL_ID);
 		b.setSmallIcon(R.drawable.notification_ongoing);
 		b.setColor(ContextCompat.getColor(this, R.color.briar_primary));
 		b.setContentTitle(getText(R.string.ongoing_notification_title));
@@ -84,7 +131,7 @@ public class BriarService extends Service {
 		Intent i = new Intent(this, NavDrawerActivity.class);
 		i.setFlags(FLAG_ACTIVITY_NEW_TASK | FLAG_ACTIVITY_CLEAR_TOP);
 		b.setContentIntent(PendingIntent.getActivity(this, 0, i, 0));
-		if (Build.VERSION.SDK_INT >= 21) {
+		if (SDK_INT >= 21) {
 			b.setCategory(CATEGORY_SERVICE);
 			b.setVisibility(VISIBILITY_SECRET);
 		}
@@ -109,12 +156,25 @@ public class BriarService extends Service {
 				}
 			}
 		}.start();
+		// Register for device shutdown broadcasts
+		receiver = new BroadcastReceiver() {
+			@Override
+			public void onReceive(Context context, Intent intent) {
+				LOG.info("Device is shutting down");
+				shutdownFromBackground();
+			}
+		};
+		IntentFilter filter = new IntentFilter();
+		filter.addAction(ACTION_SHUTDOWN);
+		filter.addAction("android.intent.action.QUICKBOOT_POWEROFF");
+		filter.addAction("com.htc.intent.action.QUICKBOOT_POWEROFF");
+		registerReceiver(receiver, filter);
 	}
 
 	private void showStartupFailureNotification(StartResult result) {
 		androidExecutor.runOnUiThread(() -> {
-			NotificationCompat.Builder b =
-					new NotificationCompat.Builder(BriarService.this);
+			NotificationCompat.Builder b = new NotificationCompat.Builder(
+					BriarService.this, FAILURE_CHANNEL_ID);
 			b.setSmallIcon(android.R.drawable.stat_notify_error);
 			b.setContentTitle(getText(
 					R.string.startup_failed_notification_title));
@@ -123,9 +183,8 @@ public class BriarService extends Service {
 			Intent i = new Intent(BriarService.this,
 					StartupFailureActivity.class);
 			i.setFlags(FLAG_ACTIVITY_NEW_TASK);
-			i.putExtra("briar.START_RESULT", result);
-			i.putExtra("briar.FAILURE_NOTIFICATION_ID",
-					FAILURE_NOTIFICATION_ID);
+			i.putExtra(EXTRA_START_RESULT, result);
+			i.putExtra(EXTRA_NOTIFICATION_ID, FAILURE_NOTIFICATION_ID);
 			b.setContentIntent(PendingIntent.getActivity(BriarService.this,
 					0, i, FLAG_UPDATE_CURRENT));
 			Object o = getSystemService(NOTIFICATION_SERVICE);
@@ -134,7 +193,7 @@ public class BriarService extends Service {
 			// Bring the dashboard to the front to clear the back stack
 			i = new Intent(BriarService.this, NavDrawerActivity.class);
 			i.setFlags(FLAG_ACTIVITY_NEW_TASK | FLAG_ACTIVITY_CLEAR_TOP);
-			i.putExtra("briar.STARTUP_FAILED", true);
+			i.putExtra(EXTRA_STARTUP_FAILED, true);
 			startActivity(i);
 		});
 	}
@@ -154,6 +213,7 @@ public class BriarService extends Service {
 		super.onDestroy();
 		LOG.info("Destroyed");
 		stopForeground(true);
+		if (receiver != null) unregisterReceiver(receiver);
 		// Stop the services in a background thread
 		new Thread() {
 			@Override
@@ -167,7 +227,48 @@ public class BriarService extends Service {
 	public void onLowMemory() {
 		super.onLowMemory();
 		LOG.warning("Memory is low");
-		// FIXME: Work out what to do about it
+		shutdownFromBackground();
+		showLowMemoryShutdownNotification();
+	}
+
+	private void shutdownFromBackground() {
+		// Stop the service
+		stopSelf();
+		// Hide the UI
+		Intent i = new Intent(this, HideUiActivity.class);
+		i.addFlags(FLAG_ACTIVITY_NEW_TASK
+				| FLAG_ACTIVITY_EXCLUDE_FROM_RECENTS
+				| FLAG_ACTIVITY_NO_ANIMATION
+				| FLAG_ACTIVITY_CLEAR_TASK);
+		startActivity(i);
+		// Wait for shutdown to complete, then exit
+		new Thread(() -> {
+			try {
+				if (started) lifecycleManager.waitForShutdown();
+			} catch (InterruptedException e) {
+				LOG.info("Interrupted while waiting for shutdown");
+			}
+			LOG.info("Exiting");
+			System.exit(0);
+		}).start();
+	}
+
+	private void showLowMemoryShutdownNotification() {
+		androidExecutor.runOnUiThread(() -> {
+			NotificationCompat.Builder b = new NotificationCompat.Builder(
+					BriarService.this, FAILURE_CHANNEL_ID);
+			b.setSmallIcon(android.R.drawable.stat_notify_error);
+			b.setContentTitle(getText(
+					R.string.low_memory_shutdown_notification_title));
+			b.setContentText(getText(
+					R.string.low_memory_shutdown_notification_text));
+			Intent i = new Intent(this, SplashScreenActivity.class);
+			b.setContentIntent(PendingIntent.getActivity(this, 0, i, 0));
+			b.setAutoCancel(true);
+			Object o = getSystemService(NOTIFICATION_SERVICE);
+			NotificationManager nm = (NotificationManager) o;
+			nm.notify(FAILURE_NOTIFICATION_ID, b.build());
+		});
 	}
 
 	/**

briar-android/src/main/java/org/briarproject/briar/android/ScreenFilterMonitorImpl.java

@@ -1,13 +1,22 @@
 package org.briarproject.briar.android;
 
+import android.annotation.SuppressLint;
 import android.app.Application;
+import android.content.BroadcastReceiver;
+import android.content.Context;
+import android.content.Intent;
+import android.content.IntentFilter;
+import android.content.SharedPreferences;
 import android.content.pm.PackageInfo;
 import android.content.pm.PackageManager;
 import android.content.pm.PackageManager.NameNotFoundException;
 import android.content.pm.Signature;
 import android.support.annotation.UiThread;
 
+import org.briarproject.bramble.api.lifecycle.Service;
+import org.briarproject.bramble.api.lifecycle.ServiceException;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.system.AndroidExecutor;
 import org.briarproject.bramble.util.StringUtils;
 import org.briarproject.briar.api.android.ScreenFilterMonitor;
 
@@ -16,23 +25,33 @@ import java.io.InputStream;
 import java.security.cert.CertificateException;
 import java.security.cert.CertificateFactory;
 import java.security.cert.X509Certificate;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashSet;
 import java.util.List;
 import java.util.Set;
-import java.util.TreeSet;
+import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.logging.Logger;
 
 import javax.annotation.Nullable;
 import javax.inject.Inject;
 
 import static android.Manifest.permission.SYSTEM_ALERT_WINDOW;
+import static android.content.Intent.ACTION_PACKAGE_ADDED;
+import static android.content.Intent.ACTION_PACKAGE_CHANGED;
+import static android.content.Intent.ACTION_PACKAGE_REMOVED;
+import static android.content.Intent.ACTION_PACKAGE_REPLACED;
 import static android.content.pm.ApplicationInfo.FLAG_SYSTEM;
 import static android.content.pm.ApplicationInfo.FLAG_UPDATED_SYSTEM_APP;
+import static android.content.pm.PackageInfo.REQUESTED_PERMISSION_GRANTED;
 import static android.content.pm.PackageManager.GET_PERMISSIONS;
 import static android.content.pm.PackageManager.GET_SIGNATURES;
+import static android.os.Build.VERSION.SDK_INT;
 import static java.util.logging.Level.WARNING;
 
 @NotNullByDefault
-class ScreenFilterMonitorImpl implements ScreenFilterMonitor {
+class ScreenFilterMonitorImpl implements ScreenFilterMonitor, Service {
 
 	private static final Logger LOG =
 			Logger.getLogger(ScreenFilterMonitorImpl.class.getName());
@@ -56,54 +75,93 @@ class ScreenFilterMonitorImpl implements ScreenFilterMonitor {
 					"82BA35E003C1B4B10DD244A8EE24FFFD333872AB5221985EDAB0FC0D" +
 					"0B145B6AA192858E79020103";
 
+	private static final String PREF_KEY_ALLOWED = "allowedOverlayApps";
+
 	private final PackageManager pm;
+	private final Application app;
+	private final AndroidExecutor androidExecutor;
+	private final SharedPreferences prefs;
+	private final AtomicBoolean used = new AtomicBoolean(false);
+
+	// UiThread
+	@Nullable
+	private BroadcastReceiver receiver = null;
+
+	// UiThread
+	@Nullable
+	private Collection<AppDetails> cachedApps = null;
 
 	@Inject
-	ScreenFilterMonitorImpl(Application app) {
+	ScreenFilterMonitorImpl(Application app, AndroidExecutor androidExecutor,
+			SharedPreferences prefs) {
 		pm = app.getPackageManager();
+		this.app = app;
+		this.androidExecutor = androidExecutor;
+		this.prefs = prefs;
 	}
 
 	@Override
 	@UiThread
-	public Set<String> getApps() {
-		Set<String> screenFilterApps = new TreeSet<>();
+	public Collection<AppDetails> getApps() {
+		if (cachedApps != null) return cachedApps;
+		Set<String> allowed = prefs.getStringSet(PREF_KEY_ALLOWED,
+				Collections.emptySet());
+		List<AppDetails> apps = new ArrayList<>();
 		List<PackageInfo> packageInfos =
 				pm.getInstalledPackages(GET_PERMISSIONS);
 		for (PackageInfo packageInfo : packageInfos) {
-			if (isOverlayApp(packageInfo)) {
-				String name = pkgToString(packageInfo);
-				if (name != null) {
-					screenFilterApps.add(name);
-				}
+			if (!allowed.contains(packageInfo.packageName)
+					&& isOverlayApp(packageInfo)) {
+				String name = getAppName(packageInfo);
+				apps.add(new AppDetails(name, packageInfo.packageName));
 			}
 		}
-		return screenFilterApps;
+		Collections.sort(apps, (a, b) -> a.name.compareTo(b.name));
+		apps = Collections.unmodifiableList(apps);
+		cachedApps = apps;
+		return apps;
 	}
 
-	// Fetches the application name for a given package.
-	@Nullable
-	private String pkgToString(PackageInfo pkgInfo) {
+	@Override
+	@UiThread
+	public void allowApps(Collection<String> packageNames) {
+		cachedApps = null;
+		Set<String> allowed = prefs.getStringSet(PREF_KEY_ALLOWED,
+				Collections.emptySet());
+		Set<String> merged = new HashSet<>(allowed);
+		merged.addAll(packageNames);
+		prefs.edit().putStringSet(PREF_KEY_ALLOWED, merged).apply();
+	}
+
+	// Returns the application name for a given package, or the package name
+	// if no application name is available
+	private String getAppName(PackageInfo pkgInfo) {
 		CharSequence seq = pm.getApplicationLabel(pkgInfo.applicationInfo);
-		if (seq != null) {
-			return seq.toString();
-		}
-		return null;
+		return seq == null ? pkgInfo.packageName : seq.toString();
 	}
 
 	// Checks if an installed package is a user app using the permission.
 	private boolean isOverlayApp(PackageInfo packageInfo) {
 		int mask = FLAG_SYSTEM | FLAG_UPDATED_SYSTEM_APP;
 		// Ignore system apps
-		if ((packageInfo.applicationInfo.flags & mask) != 0) {
-			return false;
-		}
+		if ((packageInfo.applicationInfo.flags & mask) != 0) return false;
 		// Ignore Play Services, it's effectively a system app
-		if (isPlayServices(packageInfo.packageName)) {
-			return false;
-		}
+		if (isPlayServices(packageInfo.packageName)) return false;
 		// Get permissions
 		String[] requestedPermissions = packageInfo.requestedPermissions;
-		if (requestedPermissions != null) {
+		if (requestedPermissions == null) return false;
+		if (SDK_INT >= 16 && SDK_INT < 23) {
+			// Check whether the permission has been requested and granted
+			int[] flags = packageInfo.requestedPermissionsFlags;
+			for (int i = 0; i < requestedPermissions.length; i++) {
+				if (requestedPermissions[i].equals(SYSTEM_ALERT_WINDOW)) {
+					// 'flags' may be null on Robolectric
+					return flags == null ||
+							(flags[i] & REQUESTED_PERMISSION_GRANTED) != 0;
+				}
+			}
+		} else {
+			// Check whether the permission has been requested
 			for (String requestedPermission : requestedPermissions) {
 				if (requestedPermission.equals(SYSTEM_ALERT_WINDOW)) {
 					return true;
@@ -113,6 +171,7 @@ class ScreenFilterMonitorImpl implements ScreenFilterMonitor {
 		return false;
 	}
 
+	@SuppressLint("PackageManagerGetSignatures")
 	private boolean isPlayServices(String pkg) {
 		if (!PLAY_SERVICES_PACKAGE.equals(pkg)) return false;
 		try {
@@ -135,4 +194,36 @@ class ScreenFilterMonitorImpl implements ScreenFilterMonitor {
 			return false;
 		}
 	}
+
+	@Override
+	public void startService() throws ServiceException {
+		if (used.getAndSet(true)) throw new IllegalStateException();
+		androidExecutor.runOnUiThread(() -> {
+			IntentFilter filter = new IntentFilter();
+			filter.addAction(ACTION_PACKAGE_ADDED);
+			filter.addAction(ACTION_PACKAGE_CHANGED);
+			filter.addAction(ACTION_PACKAGE_REMOVED);
+			filter.addAction(ACTION_PACKAGE_REPLACED);
+			filter.addDataScheme("package");
+			receiver = new PackageBroadcastReceiver();
+			app.registerReceiver(receiver, filter);
+			cachedApps = null;
+		});
+	}
+
+	@Override
+	public void stopService() throws ServiceException {
+		androidExecutor.runOnUiThread(() -> {
+			if (receiver != null) app.unregisterReceiver(receiver);
+		});
+	}
+
+	private class PackageBroadcastReceiver extends BroadcastReceiver {
+
+		@Override
+		@UiThread
+		public void onReceive(Context context, Intent intent) {
+			cachedApps = null;
+		}
+	}
 }

briar-android/src/main/java/org/briarproject/briar/android/StartupFailureActivity.java

@@ -3,32 +3,37 @@ package org.briarproject.briar.android;
 import android.app.NotificationManager;
 import android.content.Intent;
 import android.os.Bundle;
-import android.widget.TextView;
 
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.activity.ActivityComponent;
 import org.briarproject.briar.android.activity.BaseActivity;
+import org.briarproject.briar.android.fragment.BaseFragment.BaseFragmentListener;
+import org.briarproject.briar.android.fragment.ErrorFragment;
 
 import static org.briarproject.bramble.api.lifecycle.LifecycleManager.StartResult;
+import static org.briarproject.briar.android.BriarService.EXTRA_NOTIFICATION_ID;
+import static org.briarproject.briar.android.BriarService.EXTRA_START_RESULT;
 
-public class StartupFailureActivity extends BaseActivity {
+public class StartupFailureActivity extends BaseActivity implements
+		BaseFragmentListener {
 
 	@Override
 	public void onCreate(Bundle state) {
 		super.onCreate(state);
 
-		setContentView(R.layout.activity_startup_failure);
+		setContentView(R.layout.activity_fragment_container);
 		handleIntent(getIntent());
 	}
 
 	@Override
 	public void injectActivity(ActivityComponent component) {
-
+		component.inject(this);
 	}
 
 	private void handleIntent(Intent i) {
-		StartResult result = (StartResult) i.getSerializableExtra("briar.START_RESULT");
-		int notificationId = i.getIntExtra("briar.FAILURE_NOTIFICATION_ID", -1);
+		StartResult result =
+				(StartResult) i.getSerializableExtra(EXTRA_START_RESULT);
+		int notificationId = i.getIntExtra(EXTRA_NOTIFICATION_ID, -1);
 
 		// cancel notification
 		if (notificationId > -1) {
@@ -38,12 +43,31 @@ public class StartupFailureActivity extends BaseActivity {
 		}
 
 		// show proper error message
-		TextView view = findViewById(R.id.errorView);
-		if (result.equals(StartResult.DB_ERROR)) {
-			view.setText(getText(R.string.startup_failed_db_error));
-		} else if (result.equals(StartResult.SERVICE_ERROR)) {
-			view.setText(getText(R.string.startup_failed_service_error));
+		String errorMsg;
+		switch (result) {
+			case DATA_TOO_OLD_ERROR:
+				errorMsg = getString(R.string.startup_failed_db_error);
+				break;
+			case DATA_TOO_NEW_ERROR:
+				errorMsg =
+						getString(R.string.startup_failed_data_too_new_error);
+				break;
+			case DB_ERROR:
+				errorMsg =
+						getString(R.string.startup_failed_data_too_old_error);
+				break;
+			case SERVICE_ERROR:
+				errorMsg = getString(R.string.startup_failed_service_error);
+				break;
+			default:
+				throw new IllegalArgumentException();
 		}
+		showInitialFragment(ErrorFragment.newInstance(errorMsg));
+	}
+
+	@Override
+	public void runOnDbThread(Runnable runnable) {
+		throw new AssertionError("Deprecated and should not be used");
 	}
 
 }

briar-android/src/main/java/org/briarproject/briar/android/activity/ActivityComponent.java

@@ -3,6 +3,7 @@ package org.briarproject.briar.android.activity;
 import android.app.Activity;
 
 import org.briarproject.briar.android.AndroidComponent;
+import org.briarproject.briar.android.StartupFailureActivity;
 import org.briarproject.briar.android.blog.BlogActivity;
 import org.briarproject.briar.android.blog.BlogFragment;
 import org.briarproject.briar.android.blog.BlogModule;
@@ -21,6 +22,7 @@ import org.briarproject.briar.android.forum.CreateForumActivity;
 import org.briarproject.briar.android.forum.ForumActivity;
 import org.briarproject.briar.android.forum.ForumListFragment;
 import org.briarproject.briar.android.forum.ForumModule;
+import org.briarproject.briar.android.fragment.ScreenFilterDialogFragment;
 import org.briarproject.briar.android.introduction.ContactChooserFragment;
 import org.briarproject.briar.android.introduction.IntroductionActivity;
 import org.briarproject.briar.android.introduction.IntroductionMessageFragment;
@@ -30,6 +32,7 @@ import org.briarproject.briar.android.keyagreement.ShowQrCodeFragment;
 import org.briarproject.briar.android.login.AuthorNameFragment;
 import org.briarproject.briar.android.login.ChangePasswordActivity;
 import org.briarproject.briar.android.login.DozeFragment;
+import org.briarproject.briar.android.login.OpenDatabaseActivity;
 import org.briarproject.briar.android.login.PasswordActivity;
 import org.briarproject.briar.android.login.PasswordFragment;
 import org.briarproject.briar.android.login.SetupActivity;
@@ -86,6 +89,8 @@ public interface ActivityComponent {
 
 	void inject(SetupActivity activity);
 
+	void inject(OpenDatabaseActivity activity);
+
 	void inject(NavDrawerActivity activity);
 
 	void inject(PasswordActivity activity);
@@ -150,9 +155,13 @@ public interface ActivityComponent {
 
 	void inject(RssFeedManageActivity activity);
 
+	void inject(StartupFailureActivity activity);
+
 	// Fragments
 	void inject(AuthorNameFragment fragment);
+
 	void inject(PasswordFragment fragment);
+
 	void inject(DozeFragment fragment);
 
 	void inject(ContactListFragment fragment);
@@ -189,4 +198,5 @@ public interface ActivityComponent {
 
 	void inject(SettingsFragment fragment);
 
+	void inject(ScreenFilterDialogFragment fragment);
 }

briar-android/src/main/java/org/briarproject/briar/android/activity/ActivityModule.java

@@ -1,7 +1,6 @@
 package org.briarproject.briar.android.activity;
 
 import android.app.Activity;
-import android.content.SharedPreferences;
 
 import org.briarproject.briar.android.controller.BriarController;
 import org.briarproject.briar.android.controller.BriarControllerImpl;
@@ -19,7 +18,6 @@ import org.briarproject.briar.android.navdrawer.NavDrawerControllerImpl;
 import dagger.Module;
 import dagger.Provides;
 
-import static android.content.Context.MODE_PRIVATE;
 import static org.briarproject.briar.android.BriarService.BriarServiceConnection;
 
 @Module
@@ -57,12 +55,6 @@ public class ActivityModule {
 		return configController;
 	}
 
-	@ActivityScope
-	@Provides
-	SharedPreferences provideSharedPreferences(Activity activity) {
-		return activity.getSharedPreferences("db", MODE_PRIVATE);
-	}
-
 	@ActivityScope
 	@Provides
 	PasswordController providePasswordController(

briar-android/src/main/java/org/briarproject/briar/android/activity/BaseActivity.java

@@ -4,6 +4,8 @@ import android.os.Bundle;
 import android.os.IBinder;
 import android.support.annotation.LayoutRes;
 import android.support.annotation.UiThread;
+import android.support.v4.app.Fragment;
+import android.support.v4.app.FragmentManager;
 import android.support.v7.app.AppCompatActivity;
 import android.support.v7.widget.Toolbar;
 import android.view.View;
@@ -20,13 +22,15 @@ import org.briarproject.briar.android.controller.ActivityLifecycleController;
 import org.briarproject.briar.android.forum.ForumModule;
 import org.briarproject.briar.android.fragment.BaseFragment;
 import org.briarproject.briar.android.fragment.ScreenFilterDialogFragment;
+import org.briarproject.briar.android.util.UiUtils;
 import org.briarproject.briar.android.widget.TapSafeFrameLayout;
 import org.briarproject.briar.android.widget.TapSafeFrameLayout.OnTapFilteredListener;
 import org.briarproject.briar.api.android.ScreenFilterMonitor;
+import org.briarproject.briar.api.android.ScreenFilterMonitor.AppDetails;
 
 import java.util.ArrayList;
+import java.util.Collection;
 import java.util.List;
-import java.util.Set;
 
 import javax.annotation.Nullable;
 import javax.inject.Inject;
@@ -47,7 +51,10 @@ public abstract class BaseActivity extends AppCompatActivity
 	private final List<ActivityLifecycleController> lifecycleControllers =
 			new ArrayList<>();
 	private boolean destroyed = false;
-	private ScreenFilterDialogFragment dialogFrag;
+
+	@Nullable
+	private Toolbar toolbar = null;
+	private boolean searchedForToolbar = false;
 
 	public abstract void injectActivity(ActivityComponent component);
 
@@ -56,8 +63,8 @@ public abstract class BaseActivity extends AppCompatActivity
 	}
 
 	@Override
-	public void onCreate(@Nullable Bundle savedInstanceState) {
-		super.onCreate(savedInstanceState);
+	public void onCreate(@Nullable Bundle state) {
+		super.onCreate(state);
 
 		if (PREVENT_SCREENSHOTS) getWindow().addFlags(FLAG_SECURE);
 
@@ -96,6 +103,16 @@ public abstract class BaseActivity extends AppCompatActivity
 		for (ActivityLifecycleController alc : lifecycleControllers) {
 			alc.onActivityStart();
 		}
+		protectToolbar();
+		ScreenFilterDialogFragment f = findDialogFragment();
+		if (f != null) f.setDismissListener(this::protectToolbar);
+	}
+
+	@Nullable
+	private ScreenFilterDialogFragment findDialogFragment() {
+		Fragment f = getSupportFragmentManager().findFragmentByTag(
+				ScreenFilterDialogFragment.TAG);
+		return (ScreenFilterDialogFragment) f;
 	}
 
 	@Override
@@ -106,15 +123,6 @@ public abstract class BaseActivity extends AppCompatActivity
 		}
 	}
 
-	@Override
-	protected void onPause() {
-		super.onPause();
-		if (dialogFrag != null) {
-			dialogFrag.dismiss();
-			dialogFrag = null;
-		}
-	}
-
 	protected void showInitialFragment(BaseFragment f) {
 		getSupportFragmentManager().beginTransaction()
 				.replace(R.id.fragmentContainer, f, f.getUniqueTag())
@@ -131,14 +139,27 @@ public abstract class BaseActivity extends AppCompatActivity
 				.commit();
 	}
 
-	private void showScreenFilterWarning() {
-		if (dialogFrag != null && dialogFrag.isVisible()) return;
-		Set<String> apps = screenFilterMonitor.getApps();
-		if (apps.isEmpty()) return;
-		dialogFrag =
-				ScreenFilterDialogFragment.newInstance(new ArrayList<>(apps));
-		dialogFrag.setCancelable(false);
-		dialogFrag.show(getSupportFragmentManager(), dialogFrag.getTag());
+	private boolean showScreenFilterWarning() {
+		// If the dialog is already visible, filter the tap
+		ScreenFilterDialogFragment f = findDialogFragment();
+		if (f != null && f.isVisible()) return false;
+		Collection<AppDetails> apps = screenFilterMonitor.getApps();
+		// If all overlay apps have been allowed, allow the tap
+		if (apps.isEmpty()) return true;
+		// Show dialog unless onSaveInstanceState() has been called, see #1112
+		FragmentManager fm = getSupportFragmentManager();
+		if (!fm.isStateSaved()) {
+			// Create dialog
+			f = ScreenFilterDialogFragment.newInstance(apps);
+			// When dialog is dismissed, update protection of toolbar
+			f.setDismissListener(this::protectToolbar);
+			// Hide soft keyboard when (re)showing dialog
+			View focus = getCurrentFocus();
+			if (focus != null) hideSoftKeyboard(focus);
+			f.show(fm, ScreenFilterDialogFragment.TAG);
+		}
+		// Filter the tap
+		return false;
 	}
 
 	@Override
@@ -192,15 +213,25 @@ public abstract class BaseActivity extends AppCompatActivity
 	 * is outside the wrapper.
 	 */
 	private void protectToolbar() {
-		View decorView = getWindow().getDecorView();
-		if (decorView instanceof ViewGroup) {
-			Toolbar toolbar = findToolbar((ViewGroup) decorView);
-			if (toolbar != null) toolbar.setFilterTouchesWhenObscured(true);
+		findToolbar();
+		if (toolbar != null) {
+			boolean filter = !screenFilterMonitor.getApps().isEmpty();
+			UiUtils.setFilterTouchesWhenObscured(toolbar, filter);
 		}
 	}
 
+	private void findToolbar() {
+		if (searchedForToolbar) return;
+		View decorView = getWindow().getDecorView();
+		if (decorView instanceof ViewGroup)
+			toolbar = findToolbar((ViewGroup) decorView);
+		searchedForToolbar = true;
+	}
+
 	@Nullable
 	private Toolbar findToolbar(ViewGroup vg) {
+		// Views inside tap-safe layouts are already protected
+		if (vg instanceof TapSafeFrameLayout) return null;
 		for (int i = 0, len = vg.getChildCount(); i < len; i++) {
 			View child = vg.getChildAt(i);
 			if (child instanceof Toolbar) return (Toolbar) child;
@@ -220,23 +251,20 @@ public abstract class BaseActivity extends AppCompatActivity
 	@Override
 	public void setContentView(View v) {
 		super.setContentView(makeTapSafeWrapper(v));
-		protectToolbar();
 	}
 
 	@Override
 	public void setContentView(View v, LayoutParams layoutParams) {
 		super.setContentView(makeTapSafeWrapper(v), layoutParams);
-		protectToolbar();
 	}
 
 	@Override
 	public void addContentView(View v, LayoutParams layoutParams) {
 		super.addContentView(makeTapSafeWrapper(v), layoutParams);
-		protectToolbar();
 	}
 
 	@Override
-	public void onTapFiltered() {
-		showScreenFilterWarning();
+	public boolean shouldAllowTap() {
+		return showScreenFilterWarning();
 	}
 }

briar-android/src/main/java/org/briarproject/briar/android/activity/BriarActivity.java

@@ -16,7 +16,7 @@ import org.briarproject.briar.android.controller.BriarController;
 import org.briarproject.briar.android.controller.DbController;
 import org.briarproject.briar.android.controller.handler.UiResultHandler;
 import org.briarproject.briar.android.login.PasswordActivity;
-import org.briarproject.briar.android.panic.ExitActivity;
+import org.briarproject.briar.android.logout.ExitActivity;
 
 import java.util.logging.Logger;
 
@@ -31,11 +31,11 @@ import static android.os.Build.VERSION.SDK_INT;
 import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_DOZE_WHITELISTING;
 import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_PASSWORD;
 import static org.briarproject.briar.android.util.UiUtils.getDozeWhitelistingIntent;
+import static org.briarproject.briar.android.util.UiUtils.isSamsung7;
 
 @SuppressLint("Registered")
 public abstract class BriarActivity extends BaseActivity {
 
-	public static final String KEY_STARTUP_FAILED = "briar.STARTUP_FAILED";
 	public static final String GROUP_ID = "briar.GROUP_ID";
 	public static final String GROUP_NAME = "briar.GROUP_NAME";
 
@@ -79,6 +79,10 @@ public abstract class BriarActivity extends BaseActivity {
 
 	public void setSceneTransitionAnimation() {
 		if (SDK_INT < 21) return;
+		// workaround for #1007
+		if (isSamsung7()) {
+			return;
+		}
 		Transition slide = new Slide(Gravity.RIGHT);
 		slide.excludeTarget(android.R.id.statusBarBackground, true);
 		slide.excludeTarget(android.R.id.navigationBarBackground, true);
@@ -126,8 +130,8 @@ public abstract class BriarActivity extends BaseActivity {
 		b.setNegativeButton(R.string.cancel,
 				(dialog, which) -> dialog.dismiss());
 		b.setOnDismissListener(dialog -> {
-			CheckBox checkBox = (CheckBox) ((AlertDialog) dialog)
-					.findViewById(R.id.checkbox);
+			CheckBox checkBox =
+					((AlertDialog) dialog).findViewById(R.id.checkbox);
 			if (checkBox.isChecked())
 				briarController.doNotAskAgainForDozeWhiteListing();
 		});

briar-android/src/main/java/org/briarproject/briar/android/activity/RequestCodes.java

@@ -11,5 +11,6 @@ public interface RequestCodes {
 	int REQUEST_RINGTONE = 7;
 	int REQUEST_PERMISSION_CAMERA = 8;
 	int REQUEST_DOZE_WHITELISTING = 9;
+	int REQUEST_ENABLE_BLUETOOTH = 10;
 
 }

briar-android/src/main/java/org/briarproject/briar/android/blog/BasePostFragment.java

@@ -73,7 +73,7 @@ abstract class BasePostFragment extends BaseFragment {
 				i.setFlags(FLAG_ACTIVITY_CLEAR_TOP);
 				getContext().startActivity(i);
 			}
-		});
+		}, getFragmentManager());
 		return view;
 	}
 

briar-android/src/main/java/org/briarproject/briar/android/blog/BlogFragment.java

@@ -91,7 +91,8 @@ public class BlogFragment extends BaseFragment
 
 		View v = inflater.inflate(R.layout.fragment_blog, container, false);
 
-		adapter = new BlogPostAdapter(getActivity(), this);
+		adapter =
+				new BlogPostAdapter(getActivity(), this, getFragmentManager());
 		list = v.findViewById(R.id.postList);
 		list.setLayoutManager(new LinearLayoutManager(getActivity()));
 		list.setAdapter(adapter);

briar-android/src/main/java/org/briarproject/briar/android/blog/BlogPostAdapter.java

@@ -1,21 +1,30 @@
 package org.briarproject.briar.android.blog;
 
 import android.content.Context;
+import android.support.annotation.Nullable;
+import android.support.v4.app.FragmentManager;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
 
+import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
+import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.util.BriarAdapter;
 
-class BlogPostAdapter
-		extends BriarAdapter<BlogPostItem, BlogPostViewHolder> {
+@MethodsNotNullByDefault
+@ParametersNotNullByDefault
+class BlogPostAdapter extends BriarAdapter<BlogPostItem, BlogPostViewHolder> {
 
 	private final OnBlogPostClickListener listener;
+	@Nullable
+	private final FragmentManager fragmentManager;
 
-	BlogPostAdapter(Context ctx, OnBlogPostClickListener listener) {
+	BlogPostAdapter(Context ctx, OnBlogPostClickListener listener,
+			@Nullable FragmentManager fragmentManager) {
 		super(ctx, BlogPostItem.class);
 		this.listener = listener;
+		this.fragmentManager = fragmentManager;
 	}
 
 	@Override
@@ -23,8 +32,7 @@ class BlogPostAdapter
 			int viewType) {
 		View v = LayoutInflater.from(ctx).inflate(
 				R.layout.list_item_blog_post, parent, false);
-		BlogPostViewHolder ui = new BlogPostViewHolder(v, false, listener);
-		return ui;
+		return new BlogPostViewHolder(v, false, listener, fragmentManager);
 	}
 
 	@Override

briar-android/src/main/java/org/briarproject/briar/android/blog/BlogPostViewHolder.java

@@ -8,6 +8,7 @@ import android.support.annotation.NonNull;
 import android.support.annotation.UiThread;
 import android.support.v4.app.ActivityCompat;
 import android.support.v4.app.ActivityOptionsCompat;
+import android.support.v4.app.FragmentManager;
 import android.support.v4.view.ViewCompat;
 import android.support.v7.widget.RecyclerView;
 import android.text.Spanned;
@@ -34,6 +35,7 @@ import static org.briarproject.briar.android.blog.BasePostFragment.POST_ID;
 import static org.briarproject.briar.android.util.UiUtils.TEASER_LENGTH;
 import static org.briarproject.briar.android.util.UiUtils.getSpanned;
 import static org.briarproject.briar.android.util.UiUtils.getTeaser;
+import static org.briarproject.briar.android.util.UiUtils.isSamsung7;
 import static org.briarproject.briar.android.util.UiUtils.makeLinksClickable;
 import static org.briarproject.briar.api.blog.MessageType.POST;
 
@@ -51,12 +53,16 @@ class BlogPostViewHolder extends RecyclerView.ViewHolder {
 
 	@NonNull
 	private final OnBlogPostClickListener listener;
+	@Nullable
+	private final FragmentManager fragmentManager;
 
 	BlogPostViewHolder(View v, boolean fullText,
-			@NonNull OnBlogPostClickListener listener) {
+			@NonNull OnBlogPostClickListener listener,
+			@Nullable FragmentManager fragmentManager) {
 		super(v);
 		this.fullText = fullText;
 		this.listener = listener;
+		this.fragmentManager = fragmentManager;
 
 		ctx = v.getContext();
 		layout = v.findViewById(R.id.postLayout);
@@ -116,7 +122,7 @@ class BlogPostViewHolder extends RecyclerView.ViewHolder {
 		if (fullText) {
 			body.setText(bodyText);
 			body.setTextIsSelectable(true);
-			makeLinksClickable(body);
+			makeLinksClickable(body, fragmentManager);
 		} else {
 			body.setTextIsSelectable(false);
 			if (bodyText.length() > TEASER_LENGTH)
@@ -130,7 +136,7 @@ class BlogPostViewHolder extends RecyclerView.ViewHolder {
 			i.putExtra(GROUP_ID, item.getGroupId().getBytes());
 			i.putExtra(POST_ID, item.getId().getBytes());
 
-			if (Build.VERSION.SDK_INT >= 23) {
+			if (Build.VERSION.SDK_INT >= 23 && !isSamsung7()) {
 				ActivityOptionsCompat options =
 						makeSceneTransitionAnimation((Activity) ctx, layout,
 								getTransitionName(item.getId()));
@@ -138,6 +144,7 @@ class BlogPostViewHolder extends RecyclerView.ViewHolder {
 						options.toBundle());
 			} else {
 				// work-around for android bug #224270
+				// work-around for Samsung Android 7 bug #1007
 				ctx.startActivity(i);
 			}
 		});

briar-android/src/main/java/org/briarproject/briar/android/blog/FeedFragment.java

@@ -74,7 +74,8 @@ public class FeedFragment extends BaseFragment implements
 
 		View v = inflater.inflate(R.layout.fragment_blog, container, false);
 
-		adapter = new BlogPostAdapter(getActivity(), this);
+		adapter =
+				new BlogPostAdapter(getActivity(), this, getFragmentManager());
 
 		layoutManager = new LinearLayoutManager(getActivity());
 		list = v.findViewById(R.id.postList);

briar-android/src/main/java/org/briarproject/briar/android/blog/ReblogFragment.java

@@ -146,7 +146,7 @@ public class ReblogFragment extends BaseFragment implements TextInputListener {
 		ui.input.setVisibility(VISIBLE);
 	}
 
-	private static class ViewHolder {
+	private class ViewHolder {
 
 		private final ScrollView scrollView;
 		private final ProgressBar progressBar;
@@ -167,7 +167,7 @@ public class ReblogFragment extends BaseFragment implements TextInputListener {
 						public void onAuthorClick(BlogPostItem post) {
 							// probably don't want to allow author clicks here
 						}
-					});
+					}, getFragmentManager());
 			input = v.findViewById(R.id.inputText);
 		}
 	}

briar-android/src/main/java/org/briarproject/briar/android/controller/ConfigController.java

@@ -17,4 +17,7 @@ public interface ConfigController {
 	void deleteAccount(Context ctx);
 
 	boolean accountExists();
+
+	boolean accountSignedIn();
+
 }

briar-android/src/main/java/org/briarproject/briar/android/controller/ConfigControllerImpl.java

@@ -52,4 +52,10 @@ public class ConfigControllerImpl implements ConfigController {
 		String hex = getEncryptedDatabaseKey();
 		return hex != null && databaseConfig.databaseExists();
 	}
+
+	@Override
+	public boolean accountSignedIn() {
+		return databaseConfig.getEncryptionKey() != null;
+	}
+
 }

briar-android/src/main/java/org/briarproject/briar/android/forum/ForumListAdapter.java

@@ -52,19 +52,15 @@ class ForumListAdapter
 		// Post Count
 		int postCount = item.getPostCount();
 		if (postCount > 0) {
-			ui.avatar.setProblem(false);
 			ui.postCount.setText(ctx.getResources()
 					.getQuantityString(R.plurals.posts, postCount,
 							postCount));
 			ui.postCount.setTextColor(
-					ContextCompat
-							.getColor(ctx, R.color.briar_text_secondary));
+					ContextCompat.getColor(ctx, R.color.briar_text_secondary));
 		} else {
-			ui.avatar.setProblem(true);
 			ui.postCount.setText(ctx.getString(R.string.no_posts));
 			ui.postCount.setTextColor(
-					ContextCompat
-							.getColor(ctx, R.color.briar_text_tertiary));
+					ContextCompat.getColor(ctx, R.color.briar_text_tertiary));
 		}
 
 		// Date

briar-android/src/main/java/org/briarproject/briar/android/fragment/ErrorFragment.java

@@ -0,0 +1,65 @@
+package org.briarproject.briar.android.fragment;
+
+import android.os.Bundle;
+import android.support.annotation.Nullable;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+import android.widget.TextView;
+
+import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
+import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
+import org.briarproject.briar.R;
+import org.briarproject.briar.android.activity.ActivityComponent;
+
+
+@MethodsNotNullByDefault
+@ParametersNotNullByDefault
+public class ErrorFragment extends BaseFragment {
+
+	private static final String TAG = ErrorFragment.class.getSimpleName();
+
+	private static final String ERROR_MSG = "errorMessage";
+
+	public static ErrorFragment newInstance(String message) {
+		ErrorFragment f = new ErrorFragment();
+		Bundle args = new Bundle();
+		args.putString(ERROR_MSG, message);
+		f.setArguments(args);
+		return f;
+	}
+
+	private String errorMessage;
+
+	@Override
+	public String getUniqueTag() {
+		return TAG;
+	}
+
+	@Override
+	public void onCreate(@Nullable Bundle savedInstanceState) {
+		super.onCreate(savedInstanceState);
+
+		Bundle args = getArguments();
+		if (args == null) throw new AssertionError();
+		errorMessage = args.getString(ERROR_MSG);
+	}
+
+	@Nullable
+	@Override
+	public View onCreateView(LayoutInflater inflater,
+			@Nullable ViewGroup container,
+			@Nullable Bundle savedInstanceState) {
+		View v = inflater
+				.inflate(R.layout.fragment_error, container, false);
+		TextView msg = v.findViewById(R.id.errorMessage);
+		msg.setText(errorMessage);
+		return v;
+	}
+
+	@Override
+	public void injectFragment(ActivityComponent component) {
+		// not necessary
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/fragment/ScreenFilterDialogFragment.java

@@ -1,40 +1,106 @@
 package org.briarproject.briar.android.fragment;
 
+import android.annotation.SuppressLint;
+import android.app.Activity;
 import android.app.Dialog;
+import android.content.DialogInterface;
 import android.os.Bundle;
 import android.support.v4.app.DialogFragment;
 import android.support.v7.app.AlertDialog;
 import android.text.TextUtils;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.widget.CheckBox;
+import android.widget.TextView;
 
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
+import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.briar.R;
+import org.briarproject.briar.android.activity.BaseActivity;
+import org.briarproject.briar.api.android.ScreenFilterMonitor;
+import org.briarproject.briar.api.android.ScreenFilterMonitor.AppDetails;
 
 import java.util.ArrayList;
+import java.util.Collection;
 
 import javax.annotation.Nullable;
+import javax.inject.Inject;
 
-@NotNullByDefault
+@MethodsNotNullByDefault
+@ParametersNotNullByDefault
 public class ScreenFilterDialogFragment extends DialogFragment {
 
+	public static final String TAG = ScreenFilterDialogFragment.class.getName();
+
+	@Inject
+	ScreenFilterMonitor screenFilterMonitor;
+
+	DismissListener dismissListener = null;
+
 	public static ScreenFilterDialogFragment newInstance(
-			ArrayList<String> apps) {
+			Collection<AppDetails> apps) {
 		ScreenFilterDialogFragment frag = new ScreenFilterDialogFragment();
 		Bundle args = new Bundle();
-		args.putStringArrayList("apps", apps);
+		ArrayList<String> appNames = new ArrayList<>();
+		for (AppDetails a : apps) appNames.add(a.name);
+		args.putStringArrayList("appNames", appNames);
+		ArrayList<String> packageNames = new ArrayList<>();
+		for (AppDetails a : apps) packageNames.add(a.packageName);
+		args.putStringArrayList("packageNames", packageNames);
 		frag.setArguments(args);
 		return frag;
 	}
 
+	public void setDismissListener(DismissListener dismissListener) {
+		this.dismissListener = dismissListener;
+	}
+
+	@Override
+	public void onActivityCreated(@Nullable Bundle savedInstanceState) {
+		super.onActivityCreated(savedInstanceState);
+		Activity activity = getActivity();
+		if (activity == null) throw new IllegalStateException();
+		((BaseActivity) activity).getActivityComponent().inject(this);
+	}
+
 	@Override
 	public Dialog onCreateDialog(@Nullable Bundle savedInstanceState) {
-		AlertDialog.Builder builder = new AlertDialog.Builder(getActivity(),
+		Activity activity = getActivity();
+		if (activity == null) throw new IllegalStateException();
+		AlertDialog.Builder builder = new AlertDialog.Builder(activity,
 				R.style.BriarDialogThemeNoFilter);
 		builder.setTitle(R.string.screen_filter_title);
-		ArrayList<String> apps = getArguments().getStringArrayList("apps");
-		builder.setMessage(getString(R.string.screen_filter_body,
-				TextUtils.join("\n", apps)));
-		builder.setNeutralButton(R.string.continue_button,
-				(dialog, which) -> dialog.dismiss());
+		Bundle args = getArguments();
+		if (args == null) throw new IllegalStateException();
+		ArrayList<String> appNames = args.getStringArrayList("appNames");
+		ArrayList<String> packageNames =
+				args.getStringArrayList("packageNames");
+		if (appNames == null || packageNames == null)
+			throw new IllegalStateException();
+		LayoutInflater inflater = activity.getLayoutInflater();
+		// See https://stackoverflow.com/a/24720976/6314875
+		@SuppressLint("InflateParams")
+		View dialogView = inflater.inflate(R.layout.dialog_screen_filter, null);
+		builder.setView(dialogView);
+		TextView message = dialogView.findViewById(R.id.screen_filter_message);
+		message.setText(getString(R.string.screen_filter_body,
+				TextUtils.join("\n", appNames)));
+		CheckBox allow = dialogView.findViewById(R.id.screen_filter_checkbox);
+		builder.setNeutralButton(R.string.continue_button, (dialog, which) -> {
+			if (allow.isChecked()) screenFilterMonitor.allowApps(packageNames);
+			dialog.dismiss();
+		});
+		builder.setCancelable(false);
 		return builder.create();
 	}
+
+	@Override
+	public void onDismiss(DialogInterface dialog) {
+		super.onDismiss(dialog);
+		if (dismissListener != null) dismissListener.onDialogDismissed();
+	}
+
+	public interface DismissListener {
+		void onDialogDismissed();
+	}
 }

briar-android/src/main/java/org/briarproject/briar/android/keyagreement/CameraView.java

@@ -6,13 +6,13 @@ import android.hardware.Camera.AutoFocusCallback;
 import android.hardware.Camera.CameraInfo;
 import android.hardware.Camera.Parameters;
 import android.hardware.Camera.Size;
-import android.os.Build;
 import android.support.annotation.Nullable;
 import android.support.annotation.UiThread;
 import android.util.AttributeSet;
 import android.view.Surface;
 import android.view.SurfaceHolder;
 import android.view.SurfaceView;
+import android.view.View;
 
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
@@ -21,6 +21,7 @@ import java.io.IOException;
 import java.util.List;
 import java.util.logging.Logger;
 
+import static android.hardware.Camera.CameraInfo.CAMERA_FACING_BACK;
 import static android.hardware.Camera.CameraInfo.CAMERA_FACING_FRONT;
 import static android.hardware.Camera.Parameters.FLASH_MODE_OFF;
 import static android.hardware.Camera.Parameters.FOCUS_MODE_AUTO;
@@ -31,6 +32,7 @@ import static android.hardware.Camera.Parameters.FOCUS_MODE_FIXED;
 import static android.hardware.Camera.Parameters.FOCUS_MODE_MACRO;
 import static android.hardware.Camera.Parameters.SCENE_MODE_AUTO;
 import static android.hardware.Camera.Parameters.SCENE_MODE_BARCODE;
+import static android.os.Build.VERSION.SDK_INT;
 import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
 
@@ -38,18 +40,27 @@ import static java.util.logging.Level.WARNING;
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
 public class CameraView extends SurfaceView implements SurfaceHolder.Callback,
-		AutoFocusCallback {
+		AutoFocusCallback, View.OnClickListener {
+
+	// Heuristic for the ideal preview size - small previews don't have enough
+	// detail, large previews are slow to decode
+	private static final int IDEAL_PIXELS = 500 * 1000;
 
 	private static final int AUTO_FOCUS_RETRY_DELAY = 5000; // Milliseconds
+
 	private static final Logger LOG =
 			Logger.getLogger(CameraView.class.getName());
 
+	private final Runnable autoFocusRetry = this::retryAutoFocus;
+
 	@Nullable
 	private Camera camera = null;
+	private int cameraIndex = 0;
 	private PreviewConsumer previewConsumer = null;
 	private Surface surface = null;
 	private int displayOrientation = 0, surfaceWidth = 0, surfaceHeight = 0;
-	private boolean previewStarted = false, autoFocus = false;
+	private boolean previewStarted = false;
+	private boolean autoFocusSupported = false, autoFocusRunning = false;
 
 	public CameraView(Context context) {
 		super(context);
@@ -74,6 +85,7 @@ public class CameraView extends SurfaceView implements SurfaceHolder.Callback,
 		super.onAttachedToWindow();
 		setKeepScreenOn(true);
 		getHolder().addCallback(this);
+		setOnClickListener(this);
 	}
 
 	@Override
@@ -84,15 +96,32 @@ public class CameraView extends SurfaceView implements SurfaceHolder.Callback,
 	}
 
 	@UiThread
-	public void start() throws CameraException {
+	public void start(int rotationDegrees) throws CameraException {
 		LOG.info("Opening camera");
 		try {
-			camera = Camera.open();
+			int cameras = Camera.getNumberOfCameras();
+			if (cameras == 0) throw new CameraException("No camera");
+			// Try to find a back-facing camera
+			for (int i = 0; i < cameras; i++) {
+				CameraInfo info = new CameraInfo();
+				Camera.getCameraInfo(i, info);
+				if (info.facing == CAMERA_FACING_BACK) {
+					LOG.info("Using back-facing camera");
+					camera = Camera.open(i);
+					cameraIndex = i;
+					break;
+				}
+			}
+			// If we can't find a back-facing camera, use a front-facing one
+			if (camera == null) {
+				LOG.info("Using front-facing camera");
+				camera = Camera.open(0);
+				cameraIndex = 0;
+			}
 		} catch (RuntimeException e) {
 			throw new CameraException(e);
 		}
-		if (camera == null) throw new CameraException("No back-facing camera");
-		setDisplayOrientation(0);
+		setDisplayOrientation(rotationDegrees);
 		// Use barcode scene mode if it's available
 		Parameters params = camera.getParameters();
 		params = setSceneMode(camera, params);
@@ -157,36 +186,54 @@ public class CameraView extends SurfaceView implements SurfaceHolder.Callback,
 	@UiThread
 	private void startConsumer() throws CameraException {
 		if (camera == null) throw new CameraException("Camera is null");
-		if (autoFocus) {
+		startAutoFocus();
+		previewConsumer.start(camera, cameraIndex);
+	}
+
+	@UiThread
+	private void startAutoFocus() throws CameraException {
+		if (camera != null && autoFocusSupported && !autoFocusRunning) {
 			try {
+				removeCallbacks(autoFocusRetry);
 				camera.autoFocus(this);
+				autoFocusRunning = true;
 			} catch (RuntimeException e) {
 				throw new CameraException(e);
 			}
 		}
-		previewConsumer.start(camera);
 	}
 
 	@UiThread
 	private void stopConsumer() throws CameraException {
 		if (camera == null) throw new CameraException("Camera is null");
-		if (autoFocus) {
-			try {
-				camera.cancelAutoFocus();
-			} catch (RuntimeException e) {
-				throw new CameraException(e);
-			}
-		}
+		cancelAutoFocus();
 		previewConsumer.stop();
 	}
 
+	@UiThread
+	private void cancelAutoFocus() throws CameraException {
+		if (camera != null && autoFocusSupported && autoFocusRunning) {
+			try {
+				removeCallbacks(autoFocusRetry);
+				camera.cancelAutoFocus();
+				autoFocusRunning = false;
+			} catch (RuntimeException e) {
+				throw new CameraException(e);
+			}
+		}
+	}
+
+	/**
+	 * See {@link Camera#setDisplayOrientation(int)}.
+	 */
 	@UiThread
 	private void setDisplayOrientation(int rotationDegrees)
 			throws CameraException {
+		if (camera == null) throw new CameraException("Camera is null");
 		int orientation;
 		CameraInfo info = new CameraInfo();
 		try {
-			Camera.getCameraInfo(0, info);
+			Camera.getCameraInfo(cameraIndex, info);
 		} catch (RuntimeException e) {
 			throw new CameraException(e);
 		}
@@ -196,9 +243,11 @@ public class CameraView extends SurfaceView implements SurfaceHolder.Callback,
 		} else {
 			orientation = (info.orientation - rotationDegrees + 360) % 360;
 		}
-		if (LOG.isLoggable(INFO))
-			LOG.info("Display orientation " + orientation + " degrees");
-		if (camera == null) throw new CameraException("Camera is null");
+		if (LOG.isLoggable(INFO)) {
+			LOG.info("Screen rotation " + rotationDegrees
+					+ " degrees, camera orientation " + orientation
+					+ " degrees");
+		}
 		try {
 			camera.setDisplayOrientation(orientation);
 		} catch (RuntimeException e) {
@@ -266,8 +315,7 @@ public class CameraView extends SurfaceView implements SurfaceHolder.Callback,
 
 	@UiThread
 	private void setVideoStabilisation(Parameters params) {
-		if (Build.VERSION.SDK_INT >= 15 &&
-				params.isVideoStabilizationSupported()) {
+		if (SDK_INT >= 15 && params.isVideoStabilizationSupported()) {
 			params.setVideoStabilization(true);
 		}
 	}
@@ -294,6 +342,8 @@ public class CameraView extends SurfaceView implements SurfaceHolder.Callback,
 	@UiThread
 	private void setPreviewSize(Parameters params) {
 		if (surfaceWidth == 0 || surfaceHeight == 0) return;
+		// Choose a preview size that's close to the aspect ratio of the
+		// surface and close to the ideal size for decoding
 		float idealRatio = (float) surfaceWidth / surfaceHeight;
 		boolean rotatePreview = displayOrientation % 180 == 90;
 		List<Size> sizes = params.getSupportedPreviewSizes();
@@ -304,11 +354,12 @@ public class CameraView extends SurfaceView implements SurfaceHolder.Callback,
 			int height = rotatePreview ? size.width : size.height;
 			float ratio = (float) width / height;
 			float stretch = Math.max(ratio / idealRatio, idealRatio / ratio);
-			int pixels = width * height;
-			float score = pixels / stretch;
+			float pixels = width * height;
+			float zoom = Math.max(pixels / IDEAL_PIXELS, IDEAL_PIXELS / pixels);
+			float score = 1 / (stretch * zoom);
 			if (LOG.isLoggable(INFO)) {
 				LOG.info("Size " + size.width + "x" + size.height
-						+ ", stretch " + stretch + ", pixels " + pixels
+						+ ", stretch " + stretch + ", zoom " + zoom
 						+ ", score " + score);
 			}
 			if (bestSize == null || score > bestScore) {
@@ -325,7 +376,7 @@ public class CameraView extends SurfaceView implements SurfaceHolder.Callback,
 
 	@UiThread
 	private void enableAutoFocus(String focusMode) {
-		autoFocus = FOCUS_MODE_AUTO.equals(focusMode) ||
+		autoFocusSupported = FOCUS_MODE_AUTO.equals(focusMode) ||
 				FOCUS_MODE_MACRO.equals(focusMode);
 	}
 
@@ -339,7 +390,7 @@ public class CameraView extends SurfaceView implements SurfaceHolder.Callback,
 			} catch (RuntimeException e) {
 				throw new CameraException(e);
 			}
-			if (Build.VERSION.SDK_INT >= 15) {
+			if (SDK_INT >= 15) {
 				LOG.info("Video stabilisation enabled: "
 						+ params.getVideoStabilization());
 			}
@@ -370,8 +421,7 @@ public class CameraView extends SurfaceView implements SurfaceHolder.Callback,
 			surface.release();
 		}
 		surface = holder.getSurface();
-		// Start the preview when the camera and the surface are both ready
-		if (camera != null && !previewStarted) startPreview(holder);
+		// We'll start the preview when surfaceChanged() is called
 	}
 
 	@Override
@@ -397,7 +447,7 @@ public class CameraView extends SurfaceView implements SurfaceHolder.Callback,
 		surfaceWidth = w;
 		surfaceHeight = h;
 		if (camera == null) return; // We are stopped
-		stopPreview();
+		if (previewStarted) stopPreview();
 		try {
 			Parameters params = camera.getParameters();
 			setPreviewSize(params);
@@ -427,16 +477,23 @@ public class CameraView extends SurfaceView implements SurfaceHolder.Callback,
 
 	@Override
 	public void onAutoFocus(boolean success, Camera camera) {
-		LOG.info("Auto focus succeeded: " + success);
-		postDelayed(this::retryAutoFocus, AUTO_FOCUS_RETRY_DELAY);
+		if (LOG.isLoggable(INFO))
+			LOG.info("Auto focus succeeded: " + success);
+		autoFocusRunning = false;
+		postDelayed(autoFocusRetry, AUTO_FOCUS_RETRY_DELAY);
 	}
 
 	@UiThread
 	private void retryAutoFocus() {
 		try {
-			if (camera != null) camera.autoFocus(this);
-		} catch (RuntimeException e) {
-			LOG.log(WARNING, "Error retrying auto focus", e);
+			startAutoFocus();
+		} catch (CameraException e) {
+			LOG.log(WARNING, e.toString(), e);
 		}
 	}
+
+	@Override
+	public void onClick(View v) {
+		retryAutoFocus();
+	}
 }

briar-android/src/main/java/org/briarproject/briar/android/keyagreement/KeyAgreementActivity.java

@@ -1,9 +1,15 @@
 package org.briarproject.briar.android.keyagreement;
 
+import android.bluetooth.BluetoothAdapter;
+import android.content.BroadcastReceiver;
+import android.content.Context;
 import android.content.DialogInterface.OnClickListener;
+import android.content.Intent;
+import android.content.IntentFilter;
 import android.os.Bundle;
 import android.support.annotation.UiThread;
 import android.support.v4.app.ActivityCompat;
+import android.support.v4.app.FragmentManager;
 import android.support.v4.content.ContextCompat;
 import android.support.v7.app.AlertDialog.Builder;
 import android.support.v7.widget.Toolbar;
@@ -23,6 +29,7 @@ import org.briarproject.bramble.api.keyagreement.KeyAgreementResult;
 import org.briarproject.bramble.api.keyagreement.event.KeyAgreementFinishedEvent;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
+import org.briarproject.bramble.api.plugin.event.BluetoothEnabledEvent;
 import org.briarproject.briar.R;
 import org.briarproject.briar.R.string;
 import org.briarproject.briar.R.style;
@@ -39,9 +46,15 @@ import javax.annotation.Nullable;
 import javax.inject.Inject;
 
 import static android.Manifest.permission.CAMERA;
+import static android.bluetooth.BluetoothAdapter.ACTION_REQUEST_ENABLE;
+import static android.bluetooth.BluetoothAdapter.ACTION_STATE_CHANGED;
+import static android.bluetooth.BluetoothAdapter.EXTRA_STATE;
+import static android.bluetooth.BluetoothAdapter.STATE_ON;
 import static android.content.pm.PackageManager.PERMISSION_GRANTED;
+import static android.os.Build.VERSION.SDK_INT;
 import static android.widget.Toast.LENGTH_LONG;
 import static java.util.logging.Level.WARNING;
+import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_ENABLE_BLUETOOTH;
 import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_PERMISSION_CAMERA;
 
 @MethodsNotNullByDefault
@@ -50,6 +63,10 @@ public class KeyAgreementActivity extends BriarActivity implements
 		BaseFragmentListener, IntroScreenSeenListener, EventListener,
 		ContactExchangeListener {
 
+	private enum BluetoothState {
+		UNKNOWN, NO_ADAPTER, WAITING, REFUSED, ENABLED
+	}
+
 	private static final Logger LOG =
 			Logger.getLogger(KeyAgreementActivity.class.getName());
 
@@ -62,7 +79,10 @@ public class KeyAgreementActivity extends BriarActivity implements
 	@Inject
 	volatile IdentityManager identityManager;
 
+	private boolean isResumed = false, enableWasRequested = false;
 	private boolean continueClicked, gotCameraPermission;
+	private BluetoothState bluetoothState = BluetoothState.UNKNOWN;
+	private BroadcastReceiver bluetoothReceiver = null;
 
 	@Override
 	public void injectActivity(ActivityComponent component) {
@@ -84,6 +104,15 @@ public class KeyAgreementActivity extends BriarActivity implements
 		if (state == null) {
 			showInitialFragment(IntroFragment.newInstance());
 		}
+		IntentFilter filter = new IntentFilter(ACTION_STATE_CHANGED);
+		bluetoothReceiver = new BluetoothStateReceiver();
+		registerReceiver(bluetoothReceiver, filter);
+	}
+
+	@Override
+	public void onDestroy() {
+		super.onDestroy();
+		if (bluetoothReceiver != null) unregisterReceiver(bluetoothReceiver);
 	}
 
 	@Override
@@ -112,29 +141,80 @@ public class KeyAgreementActivity extends BriarActivity implements
 	@Override
 	protected void onPostResume() {
 		super.onPostResume();
+		isResumed = true;
 		// Workaround for
 		// https://code.google.com/p/android/issues/detail?id=190966
-		if (continueClicked && gotCameraPermission) {
-			showQrCodeFragment();
-		}
+		if (canShowQrCodeFragment()) showQrCodeFragment();
+	}
+
+	boolean canShowQrCodeFragment() {
+		return isResumed && continueClicked
+				&& (SDK_INT < 23 || gotCameraPermission)
+				&& bluetoothState != BluetoothState.UNKNOWN
+				&& bluetoothState != BluetoothState.WAITING;
+	}
+
+	@Override
+	protected void onPause() {
+		super.onPause();
+		isResumed = false;
 	}
 
 	@Override
 	public void showNextScreen() {
-		// FIXME #824
-		// showNextFragment(ShowQrCodeFragment.newInstance());
 		continueClicked = true;
 		if (checkPermissions()) {
-			showQrCodeFragment();
+			if (shouldRequestEnableBluetooth()) requestEnableBluetooth();
+			else if (canShowQrCodeFragment()) showQrCodeFragment();
 		}
 	}
 
+	private boolean shouldRequestEnableBluetooth() {
+		return bluetoothState == BluetoothState.UNKNOWN
+				|| bluetoothState == BluetoothState.REFUSED;
+	}
+
+	private void requestEnableBluetooth() {
+		BluetoothAdapter bt = BluetoothAdapter.getDefaultAdapter();
+		if (bt == null) {
+			setBluetoothState(BluetoothState.NO_ADAPTER);
+		} else if (bt.isEnabled()) {
+			setBluetoothState(BluetoothState.ENABLED);
+		} else {
+			enableWasRequested = true;
+			setBluetoothState(BluetoothState.WAITING);
+			Intent i = new Intent(ACTION_REQUEST_ENABLE);
+			startActivityForResult(i, REQUEST_ENABLE_BLUETOOTH);
+		}
+	}
+
+	private void setBluetoothState(BluetoothState bluetoothState) {
+		LOG.info("Setting Bluetooth state to " + bluetoothState);
+		this.bluetoothState = bluetoothState;
+		if (enableWasRequested && bluetoothState == BluetoothState.ENABLED) {
+			eventBus.broadcast(new BluetoothEnabledEvent());
+			enableWasRequested = false;
+		}
+		if (canShowQrCodeFragment()) showQrCodeFragment();
+	}
+
+	@Override
+	public void onActivityResult(int request, int result, Intent data) {
+		// If the request was granted we'll catch the state change event
+		if (request == REQUEST_ENABLE_BLUETOOTH && result == RESULT_CANCELED)
+			setBluetoothState(BluetoothState.REFUSED);
+	}
+
 	private void showQrCodeFragment() {
-		BaseFragment f = ShowQrCodeFragment.newInstance();
-		getSupportFragmentManager().beginTransaction()
-				.replace(R.id.fragmentContainer, f, f.getUniqueTag())
-				.addToBackStack(f.getUniqueTag())
-				.commit();
+		// FIXME #824
+		FragmentManager fm = getSupportFragmentManager();
+		if (fm.findFragmentByTag(ShowQrCodeFragment.TAG) == null) {
+			BaseFragment f = ShowQrCodeFragment.newInstance();
+			fm.beginTransaction()
+					.replace(R.id.fragmentContainer, f, f.getUniqueTag())
+					.addToBackStack(f.getUniqueTag())
+					.commit();
+		}
 	}
 
 	private boolean checkPermissions() {
@@ -154,8 +234,10 @@ public class KeyAgreementActivity extends BriarActivity implements
 			} else {
 				requestPermission();
 			}
+			gotCameraPermission = false;
 			return false;
 		} else {
+			gotCameraPermission = true;
 			return true;
 		}
 	}
@@ -174,6 +256,7 @@ public class KeyAgreementActivity extends BriarActivity implements
 			if (grantResults.length > 0 &&
 					grantResults[0] == PERMISSION_GRANTED) {
 				gotCameraPermission = true;
+				showNextScreen();
 			} else {
 				if (!ActivityCompat.shouldShowRequestPermissionRationale(this,
 						CAMERA)) {
@@ -258,4 +341,14 @@ public class KeyAgreementActivity extends BriarActivity implements
 			finish();
 		});
 	}
+
+	private class BluetoothStateReceiver extends BroadcastReceiver {
+
+		@Override
+		public void onReceive(Context context, Intent intent) {
+			int state = intent.getIntExtra(EXTRA_STATE, 0);
+			if (state == STATE_ON) setBluetoothState(BluetoothState.ENABLED);
+			else setBluetoothState(BluetoothState.UNKNOWN);
+		}
+	}
 }

briar-android/src/main/java/org/briarproject/briar/android/keyagreement/PreviewConsumer.java

@@ -10,7 +10,7 @@ import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 interface PreviewConsumer {
 
 	@UiThread
-	void start(Camera camera);
+	void start(Camera camera, int cameraIndex);
 
 	@UiThread
 	void stop();

briar-android/src/main/java/org/briarproject/briar/android/keyagreement/QrCodeDecoder.java

@@ -1,6 +1,7 @@
 package org.briarproject.briar.android.keyagreement;
 
 import android.hardware.Camera;
+import android.hardware.Camera.CameraInfo;
 import android.hardware.Camera.PreviewCallback;
 import android.hardware.Camera.Size;
 import android.os.AsyncTask;
@@ -36,20 +37,23 @@ class QrCodeDecoder implements PreviewConsumer, PreviewCallback {
 	private final ResultCallback callback;
 
 	private Camera camera = null;
+	private int cameraIndex = 0;
 
 	QrCodeDecoder(ResultCallback callback) {
 		this.callback = callback;
 	}
 
 	@Override
-	public void start(Camera camera) {
+	public void start(Camera camera, int cameraIndex) {
 		this.camera = camera;
+		this.cameraIndex = cameraIndex;
 		askForPreviewFrame();
 	}
 
 	@Override
 	public void stop() {
 		camera = null;
+		cameraIndex = 0;
 	}
 
 	@UiThread
@@ -63,43 +67,54 @@ class QrCodeDecoder implements PreviewConsumer, PreviewCallback {
 		if (camera == this.camera) {
 			try {
 				Size size = camera.getParameters().getPreviewSize();
-				new DecoderTask(data, size.width, size.height).execute();
+				// The preview should be in NV21 format: width * height bytes of
+				// Y followed by width * height / 2 bytes of interleaved U and V
+				if (data.length == size.width * size.height * 3 / 2) {
+					CameraInfo info = new CameraInfo();
+					Camera.getCameraInfo(cameraIndex, info);
+					new DecoderTask(data, size.width, size.height,
+							info.orientation).execute();
+				} else {
+					// Camera parameters have changed - ask for a new preview
+					LOG.info("Preview size does not match camera parameters");
+					askForPreviewFrame();
+				}
 			} catch (RuntimeException e) {
 				LOG.log(WARNING, "Error getting camera parameters.", e);
 			}
+		} else {
+			LOG.info("Camera has changed, ignoring preview frame");
 		}
 	}
 
 	private class DecoderTask extends AsyncTask<Void, Void, Void> {
 
 		private final byte[] data;
-		private final int width, height;
+		private final int width, height, orientation;
 
-		private DecoderTask(byte[] data, int width, int height) {
+		private DecoderTask(byte[] data, int width, int height,
+				int orientation) {
 			this.data = data;
 			this.width = width;
 			this.height = height;
+			this.orientation = orientation;
 		}
 
 		@Override
 		protected Void doInBackground(Void... params) {
-			long now = System.currentTimeMillis();
-			LuminanceSource src = new PlanarYUVLuminanceSource(data, width,
-					height, 0, 0, width, height, false);
-			BinaryBitmap bitmap = new BinaryBitmap(new HybridBinarizer(src));
-			Result result = null;
+			BinaryBitmap bitmap = binarize(data, width, height, orientation);
+			Result result;
 			try {
 				result = reader.decode(bitmap);
 			} catch (ReaderException e) {
-				return null; // No barcode found
+				// No barcode found
+				return null;
 			} catch (RuntimeException e) {
-				return null; // Preview data did not match width and height
+				LOG.warning("Invalid preview frame");
+				return null;
 			} finally {
 				reader.reset();
 			}
-			long duration = System.currentTimeMillis() - now;
-			if (LOG.isLoggable(INFO))
-				LOG.info("Decoding barcode took " + duration + " ms");
 			callback.handleResult(result);
 			return null;
 		}
@@ -110,6 +125,19 @@ class QrCodeDecoder implements PreviewConsumer, PreviewCallback {
 		}
 	}
 
+	private static BinaryBitmap binarize(byte[] data, int width, int height,
+			int orientation) {
+		// Crop to a square at the top (portrait) or left (landscape) of the
+		// screen - this will be faster to decode and should include
+		// everything visible in the viewfinder
+		int crop = Math.min(width, height);
+		int left = orientation >= 180 ? width - crop : 0;
+		int top = orientation >= 180 ? height - crop : 0;
+		LuminanceSource src = new PlanarYUVLuminanceSource(data, width,
+				height, left, top, crop, crop, false);
+		return new BinaryBitmap(new HybridBinarizer(src));
+	}
+
 	@NotNullByDefault
 	interface ResultCallback {
 

briar-android/src/main/java/org/briarproject/briar/android/keyagreement/QrCodeUtils.java

@@ -32,21 +32,24 @@ class QrCodeUtils {
 			// Generate QR code
 			BitMatrix encoded = new QRCodeWriter().encode(input, QR_CODE,
 					smallestDimen, smallestDimen);
-			// Convert QR code to Bitmap
-			int width = encoded.getWidth();
-			int height = encoded.getHeight();
-			int[] pixels = new int[width * height];
-			for (int x = 0; x < width; x++) {
-				for (int y = 0; y < height; y++) {
-					pixels[y * width + x] = encoded.get(x, y) ? BLACK : WHITE;
-				}
-			}
-			Bitmap qr = Bitmap.createBitmap(width, height, ARGB_8888);
-			qr.setPixels(pixels, 0, width, 0, 0, width, height);
-			return qr;
+			return renderQrCode(encoded);
 		} catch (WriterException e) {
 			if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
 			return null;
 		}
 	}
+
+	private static Bitmap renderQrCode(BitMatrix matrix) {
+		int width = matrix.getWidth();
+		int height = matrix.getHeight();
+		int[] pixels = new int[width * height];
+		for (int x = 0; x < width; x++) {
+			for (int y = 0; y < height; y++) {
+				pixels[y * width + x] = matrix.get(x, y) ? BLACK : WHITE;
+			}
+		}
+		Bitmap qr = Bitmap.createBitmap(width, height, ARGB_8888);
+		qr.setPixels(pixels, 0, width, 0, 0, width, height);
+		return qr;
+	}
 }

briar-android/src/main/java/org/briarproject/briar/android/keyagreement/ShowQrCodeFragment.java

@@ -1,21 +1,22 @@
 package org.briarproject.briar.android.keyagreement;
 
-import android.bluetooth.BluetoothAdapter;
-import android.content.BroadcastReceiver;
 import android.content.Context;
-import android.content.Intent;
-import android.content.IntentFilter;
 import android.graphics.Bitmap;
+import android.hardware.Camera;
 import android.os.AsyncTask;
 import android.os.Bundle;
 import android.support.annotation.UiThread;
 import android.util.Base64;
 import android.util.DisplayMetrics;
+import android.view.Display;
 import android.view.LayoutInflater;
+import android.view.Surface;
 import android.view.View;
 import android.view.ViewGroup;
 import android.view.animation.AlphaAnimation;
 import android.widget.ImageView;
+import android.widget.LinearLayout;
+import android.widget.LinearLayout.LayoutParams;
 import android.widget.TextView;
 import android.widget.Toast;
 
@@ -37,7 +38,6 @@ import org.briarproject.bramble.api.keyagreement.event.KeyAgreementWaitingEvent;
 import org.briarproject.bramble.api.lifecycle.IoExecutor;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
-import org.briarproject.bramble.api.plugin.event.EnableBluetoothEvent;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.activity.ActivityComponent;
 import org.briarproject.briar.android.fragment.BaseEventFragment;
@@ -49,12 +49,11 @@ import java.util.logging.Logger;
 import javax.annotation.Nullable;
 import javax.inject.Inject;
 
-import static android.bluetooth.BluetoothAdapter.ACTION_STATE_CHANGED;
-import static android.bluetooth.BluetoothAdapter.EXTRA_STATE;
-import static android.bluetooth.BluetoothAdapter.STATE_ON;
 import static android.content.pm.ActivityInfo.SCREEN_ORIENTATION_NOSENSOR;
 import static android.view.View.INVISIBLE;
 import static android.view.View.VISIBLE;
+import static android.view.ViewGroup.LayoutParams.MATCH_PARENT;
+import static android.widget.LinearLayout.HORIZONTAL;
 import static android.widget.Toast.LENGTH_LONG;
 import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
@@ -64,7 +63,8 @@ import static java.util.logging.Level.WARNING;
 public class ShowQrCodeFragment extends BaseEventFragment
 		implements QrCodeDecoder.ResultCallback {
 
-	private static final String TAG = ShowQrCodeFragment.class.getName();
+	static final String TAG = ShowQrCodeFragment.class.getName();
+
 	private static final Logger LOG = Logger.getLogger(TAG);
 
 	@Inject
@@ -85,9 +85,9 @@ public class ShowQrCodeFragment extends BaseEventFragment
 	private ImageView qrCode;
 	private TextView mainProgressTitle;
 	private ViewGroup mainProgressContainer;
+	private boolean fullscreen = false;
 
-	private BluetoothStateReceiver receiver;
-	private boolean gotRemotePayload, waitingForBluetooth;
+	private boolean gotRemotePayload;
 	private volatile boolean gotLocalPayload;
 	private KeyAgreementTask task;
 
@@ -130,6 +130,34 @@ public class ShowQrCodeFragment extends BaseEventFragment
 		qrCode = view.findViewById(R.id.qr_code);
 		mainProgressTitle = view.findViewById(R.id.title_progress_bar);
 		mainProgressContainer = view.findViewById(R.id.container_progress);
+		ImageView fullscreenButton = view.findViewById(R.id.fullscreen_button);
+		fullscreenButton.setOnClickListener(v -> {
+			View qrCodeContainer = view.findViewById(R.id.qr_code_container);
+			LinearLayout cameraOverlay = view.findViewById(R.id.camera_overlay);
+			LayoutParams statusParams, qrCodeParams;
+			if (fullscreen) {
+				// Shrink the QR code container to fill half its parent
+				if (cameraOverlay.getOrientation() == HORIZONTAL) {
+					statusParams = new LayoutParams(0, MATCH_PARENT, 1f);
+					qrCodeParams = new LayoutParams(0, MATCH_PARENT, 1f);
+				} else {
+					statusParams = new LayoutParams(MATCH_PARENT, 0, 1f);
+					qrCodeParams = new LayoutParams(MATCH_PARENT, 0, 1f);
+				}
+				fullscreenButton.setImageResource(
+						R.drawable.ic_fullscreen_black_48dp);
+			} else {
+				// Grow the QR code container to fill its parent
+				statusParams = new LayoutParams(0, 0, 0f);
+				qrCodeParams = new LayoutParams(MATCH_PARENT, MATCH_PARENT, 1f);
+				fullscreenButton.setImageResource(
+						R.drawable.ic_fullscreen_exit_black_48dp);
+			}
+			statusView.setLayoutParams(statusParams);
+			qrCodeContainer.setLayoutParams(qrCodeParams);
+			cameraOverlay.invalidate();
+			fullscreen = !fullscreen;
+		});
 	}
 
 	@Override
@@ -144,23 +172,29 @@ public class ShowQrCodeFragment extends BaseEventFragment
 	public void onStart() {
 		super.onStart();
 		try {
-			cameraView.start();
+			cameraView.start(getScreenRotationDegrees());
 		} catch (CameraException e) {
 			logCameraExceptionAndFinish(e);
 		}
-		// Listen for changes to the Bluetooth state
-		IntentFilter filter = new IntentFilter();
-		filter.addAction(ACTION_STATE_CHANGED);
-		receiver = new BluetoothStateReceiver();
-		getActivity().registerReceiver(receiver, filter);
+		startListening();
+	}
 
-		// Enable BT adapter if it is not already on.
-		BluetoothAdapter adapter = BluetoothAdapter.getDefaultAdapter();
-		if (adapter != null && !adapter.isEnabled()) {
-			waitingForBluetooth = true;
-			eventBus.broadcast(new EnableBluetoothEvent());
-		} else {
-			startListening();
+	/**
+	 * See {@link Camera#setDisplayOrientation(int)}.
+	 */
+	private int getScreenRotationDegrees() {
+		Display d = getActivity().getWindowManager().getDefaultDisplay();
+		switch (d.getRotation()) {
+			case Surface.ROTATION_0:
+				return 0;
+			case Surface.ROTATION_90:
+				return 90;
+			case Surface.ROTATION_180:
+				return 180;
+			case Surface.ROTATION_270:
+				return 270;
+			default:
+				throw new AssertionError();
 		}
 	}
 
@@ -168,7 +202,6 @@ public class ShowQrCodeFragment extends BaseEventFragment
 	public void onStop() {
 		super.onStop();
 		stopListening();
-		if (receiver != null) getActivity().unregisterReceiver(receiver);
 		try {
 			cameraView.stop();
 		} catch (CameraException e) {
@@ -205,6 +238,15 @@ public class ShowQrCodeFragment extends BaseEventFragment
 
 	@UiThread
 	private void reset() {
+		// If we've stopped the camera view, restart it
+		if (gotRemotePayload) {
+			try {
+				cameraView.start(getScreenRotationDegrees());
+			} catch (CameraException e) {
+				logCameraExceptionAndFinish(e);
+				return;
+			}
+		}
 		statusView.setVisibility(INVISIBLE);
 		cameraView.setVisibility(VISIBLE);
 		gotRemotePayload = false;
@@ -219,12 +261,17 @@ public class ShowQrCodeFragment extends BaseEventFragment
 			if (LOG.isLoggable(INFO))
 				LOG.info("Remote payload is " + encoded.length + " bytes");
 			Payload remotePayload = payloadParser.parse(encoded);
+			gotRemotePayload = true;
+			cameraView.stop();
 			cameraView.setVisibility(INVISIBLE);
 			statusView.setVisibility(VISIBLE);
 			status.setText(R.string.connecting_to_device);
 			task.connectAndRunProtocol(remotePayload);
+		} catch (CameraException e) {
+			logCameraExceptionAndFinish(e);
 		} catch (IOException | IllegalArgumentException e) {
-			// TODO show failure
+			if (LOG.isLoggable(WARNING)) LOG.log(WARNING, "QR Code Invalid", e);
+			reset();
 			Toast.makeText(getActivity(), R.string.qr_code_invalid,
 					LENGTH_LONG).show();
 		}
@@ -262,6 +309,7 @@ public class ShowQrCodeFragment extends BaseEventFragment
 		new AsyncTask<Void, Void, Bitmap>() {
 
 			@Override
+			@Nullable
 			protected Bitmap doInBackground(Void... params) {
 				byte[] encoded = payloadEncoder.encode(payload);
 				if (LOG.isLoggable(INFO))
@@ -326,13 +374,8 @@ public class ShowQrCodeFragment extends BaseEventFragment
 		runOnUiThreadUnlessDestroyed(() -> {
 			LOG.info("Got result from decoder");
 			// Ignore results until the KeyAgreementTask is ready
-			if (!gotLocalPayload) {
-				return;
-			}
-			if (!gotRemotePayload) {
-				gotRemotePayload = true;
-				qrCodeScanned(result.getText());
-			}
+			if (!gotLocalPayload) return;
+			if (!gotRemotePayload) qrCodeScanned(result.getText());
 		});
 	}
 
@@ -340,16 +383,4 @@ public class ShowQrCodeFragment extends BaseEventFragment
 	protected void finish() {
 		getActivity().getSupportFragmentManager().popBackStack();
 	}
-
-	private class BluetoothStateReceiver extends BroadcastReceiver {
-		@UiThread
-		@Override
-		public void onReceive(Context ctx, Intent intent) {
-			int state = intent.getIntExtra(EXTRA_STATE, 0);
-			if (state == STATE_ON && waitingForBluetooth) {
-				waitingForBluetooth = false;
-				startListening();
-			}
-		}
-	}
 }

briar-android/src/main/java/org/briarproject/briar/android/login/ChangePasswordActivity.java

@@ -17,7 +17,7 @@ import android.widget.Toast;
 
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.activity.ActivityComponent;
-import org.briarproject.briar.android.activity.BaseActivity;
+import org.briarproject.briar.android.activity.BriarActivity;
 import org.briarproject.briar.android.controller.handler.UiResultHandler;
 import org.briarproject.briar.android.util.UiUtils;
 
@@ -27,7 +27,7 @@ import static android.view.View.INVISIBLE;
 import static android.view.View.VISIBLE;
 import static org.briarproject.bramble.api.crypto.PasswordStrengthEstimator.QUITE_WEAK;
 
-public class ChangePasswordActivity extends BaseActivity
+public class ChangePasswordActivity extends BriarActivity
 		implements OnClickListener, OnEditorActionListener {
 
 	@Inject

briar-android/src/main/java/org/briarproject/briar/android/login/DozeFragment.java

@@ -1,17 +1,19 @@
 package org.briarproject.briar.android.login;
 
 import android.annotation.SuppressLint;
-import android.annotation.TargetApi;
 import android.content.Intent;
 import android.os.Bundle;
+import android.support.annotation.Nullable;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
 import android.widget.Button;
 import android.widget.ProgressBar;
 
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.activity.ActivityComponent;
+import org.briarproject.briar.android.login.PowerView.OnCheckedChangedListener;
 import org.briarproject.briar.android.util.UiUtils;
 
 import static android.view.View.INVISIBLE;
@@ -19,12 +21,15 @@ import static android.view.View.VISIBLE;
 import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_DOZE_WHITELISTING;
 import static org.briarproject.briar.android.util.UiUtils.showOnboardingDialog;
 
-@TargetApi(23)
-public class DozeFragment extends SetupFragment {
+@NotNullByDefault
+public class DozeFragment extends SetupFragment
+		implements OnCheckedChangedListener {
 
 	private final static String TAG = DozeFragment.class.getName();
 
-	private Button dozeButton;
+	private DozeView dozeView;
+	private HuaweiView huaweiView;
+	private Button next;
 	private ProgressBar progressBar;
 	private boolean secondAttempt = false;
 
@@ -33,15 +38,22 @@ public class DozeFragment extends SetupFragment {
 	}
 
 	@Override
-	public View onCreateView(LayoutInflater inflater, ViewGroup container,
-			Bundle savedInstanceState) {
+	public View onCreateView(LayoutInflater inflater,
+			@Nullable ViewGroup container,
+			@Nullable Bundle savedInstanceState) {
 		getActivity().setTitle(getString(R.string.setup_doze_title));
+		setHasOptionsMenu(false);
 		View v = inflater.inflate(R.layout.fragment_setup_doze, container,
 						false);
-		dozeButton = v.findViewById(R.id.dozeButton);
+		dozeView = v.findViewById(R.id.dozeView);
+		dozeView.setOnCheckedChangedListener(this);
+		huaweiView = v.findViewById(R.id.huaweiView);
+		huaweiView.setOnCheckedChangedListener(this);
+		next = v.findViewById(R.id.next);
 		progressBar = v.findViewById(R.id.progress);
 
-		dozeButton.setOnClickListener(view -> askForDozeWhitelisting());
+		dozeView.setOnButtonClickListener(this::askForDozeWhitelisting);
+		next.setOnClickListener(this);
 
 		return v;
 	}
@@ -65,25 +77,34 @@ public class DozeFragment extends SetupFragment {
 	public void onActivityResult(int request, int result, Intent data) {
 		super.onActivityResult(request, result, data);
 		if (request == REQUEST_DOZE_WHITELISTING) {
-			if (!setupController.needsDozeWhitelisting() || secondAttempt) {
-				dozeButton.setEnabled(false);
-				onClick(dozeButton);
-			} else {
+			if (!dozeView.needsToBeShown() || secondAttempt) {
+				dozeView.setChecked(true);
+			} else if (getContext() != null) {
 				secondAttempt = true;
 				showOnboardingDialog(getContext(), getHelpText());
 			}
 		}
 	}
 
+	@Override
+	public void onCheckedChanged() {
+		if (dozeView.isChecked() && huaweiView.isChecked()) {
+			next.setEnabled(true);
+		} else {
+			next.setEnabled(false);
+		}
+	}
+
 	@SuppressLint("BatteryLife")
 	private void askForDozeWhitelisting() {
+		if (getContext() == null) return;
 		Intent i = UiUtils.getDozeWhitelistingIntent(getContext());
 		startActivityForResult(i, REQUEST_DOZE_WHITELISTING);
 	}
 
 	@Override
 	public void onClick(View view) {
-		dozeButton.setVisibility(INVISIBLE);
+		next.setVisibility(INVISIBLE);
 		progressBar.setVisibility(VISIBLE);
 		setupController.createAccount();
 	}

briar-android/src/main/java/org/briarproject/briar/android/login/DozeView.java

@@ -0,0 +1,60 @@
+package org.briarproject.briar.android.login;
+
+
+import android.content.Context;
+import android.support.annotation.Nullable;
+import android.support.annotation.UiThread;
+import android.util.AttributeSet;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.briar.R;
+
+import static org.briarproject.briar.android.util.UiUtils.needsDozeWhitelisting;
+
+@UiThread
+@NotNullByDefault
+class DozeView extends PowerView {
+
+	@Nullable
+	private Runnable onButtonClickListener;
+
+	public DozeView(Context context) {
+		this(context, null);
+	}
+
+	public DozeView(Context context, @Nullable AttributeSet attrs) {
+		this(context, attrs, 0);
+	}
+
+	public DozeView(Context context, @Nullable AttributeSet attrs,
+			int defStyleAttr) {
+		super(context, attrs, defStyleAttr);
+		setText(R.string.setup_doze_intro);
+		setButtonText(R.string.setup_doze_button);
+	}
+
+	@Override
+	public boolean needsToBeShown() {
+		return needsToBeShown(getContext());
+	}
+
+	public static boolean needsToBeShown(Context context) {
+		return needsDozeWhitelisting(context);
+	}
+
+	@Override
+	protected int getHelpText() {
+		return R.string.setup_doze_explanation;
+	}
+
+	@Override
+	protected void onButtonClick() {
+		if (onButtonClickListener == null) throw new IllegalStateException();
+		onButtonClickListener.run();
+	}
+
+	public void setOnButtonClickListener(Runnable runnable) {
+		onButtonClickListener = runnable;
+	}
+
+}