Don't treat an incoming connection as an attempt to raise the limit.

Detect and close dead Bluetooth connections

See merge request briar/briar!1246

bramble-android/build.gradle

@@ -38,7 +38,7 @@ configurations {
 
 dependencies {
 	implementation project(path: ':bramble-core', configuration: 'default')
-	tor 'org.briarproject:tor-android:0.3.5.9@zip'
+	tor 'org.briarproject:tor-android:0.3.5.10@zip'
 	tor 'org.briarproject:obfs4proxy-android:0.0.11-2@zip'
 
 	annotationProcessor 'com.google.dagger:dagger-compiler:2.24'

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

@@ -8,34 +8,24 @@ import android.content.BroadcastReceiver;
 import android.content.Context;
 import android.content.Intent;
 import android.content.IntentFilter;
-import android.os.ParcelUuid;
-import android.os.Parcelable;
 
-import org.briarproject.bramble.api.Pair;
+import org.briarproject.bramble.api.io.TimeoutMonitor;
 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.DiscoveryHandler;
 import org.briarproject.bramble.api.plugin.PluginCallback;
 import org.briarproject.bramble.api.plugin.PluginException;
 import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
-import org.briarproject.bramble.api.properties.TransportProperties;
 import org.briarproject.bramble.api.system.AndroidExecutor;
 import org.briarproject.bramble.api.system.Clock;
 import org.briarproject.bramble.util.AndroidUtils;
 import org.briarproject.bramble.util.IoUtils;
 
 import java.io.IOException;
-import java.lang.reflect.InvocationTargetException;
-import java.lang.reflect.Method;
-import java.nio.ByteBuffer;
 import java.security.SecureRandom;
 import java.util.ArrayList;
-import java.util.HashMap;
+import java.util.Collection;
 import java.util.List;
-import java.util.Map;
-import java.util.Set;
-import java.util.TreeSet;
 import java.util.UUID;
 import java.util.concurrent.BlockingQueue;
 import java.util.concurrent.ExecutionException;
@@ -57,25 +47,15 @@ import static android.bluetooth.BluetoothAdapter.SCAN_MODE_NONE;
 import static android.bluetooth.BluetoothAdapter.STATE_OFF;
 import static android.bluetooth.BluetoothAdapter.STATE_ON;
 import static android.bluetooth.BluetoothDevice.ACTION_FOUND;
-import static android.bluetooth.BluetoothDevice.ACTION_UUID;
 import static android.bluetooth.BluetoothDevice.DEVICE_TYPE_LE;
 import static android.bluetooth.BluetoothDevice.EXTRA_DEVICE;
-import static android.bluetooth.BluetoothDevice.EXTRA_UUID;
 import static android.os.Build.VERSION.SDK_INT;
-import static java.nio.ByteOrder.LITTLE_ENDIAN;
-import static java.util.Arrays.asList;
-import static java.util.Collections.emptyList;
 import static java.util.Collections.shuffle;
 import static java.util.concurrent.TimeUnit.MILLISECONDS;
 import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
 import static java.util.logging.Logger.getLogger;
-import static org.briarproject.bramble.api.nullsafety.NullSafety.requireNonNull;
-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.util.LogUtils.logException;
 import static org.briarproject.bramble.util.PrivacyUtils.scrubMacAddress;
-import static org.briarproject.bramble.util.StringUtils.isNullOrEmpty;
 
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
@@ -84,9 +64,7 @@ class AndroidBluetoothPlugin extends BluetoothPlugin<BluetoothServerSocket> {
 	private static final Logger LOG =
 			getLogger(AndroidBluetoothPlugin.class.getName());
 
-	private static final int MIN_DEVICE_DISCOVERY_MS = 2_000;
+	private static final int MAX_DISCOVERY_MS = 10_000;
-	private static final int MAX_DEVICE_DISCOVERY_MS = 30_000;
-	private static final int MAX_SERVICE_DISCOVERY_MS = 15_000;
 
 	private final AndroidExecutor androidExecutor;
 	private final Context appContext;
@@ -99,11 +77,12 @@ class AndroidBluetoothPlugin extends BluetoothPlugin<BluetoothServerSocket> {
 	private volatile BluetoothAdapter adapter = null;
 
 	AndroidBluetoothPlugin(BluetoothConnectionLimiter connectionLimiter,
-			Executor ioExecutor, AndroidExecutor androidExecutor,
+			TimeoutMonitor timeoutMonitor, Executor ioExecutor,
-			Context appContext, SecureRandom secureRandom, Clock clock,
+			SecureRandom secureRandom, AndroidExecutor androidExecutor,
-			Backoff backoff, PluginCallback callback, int maxLatency) {
+			Context appContext, Clock clock, Backoff backoff,
-		super(connectionLimiter, ioExecutor, secureRandom, backoff, callback,
+			PluginCallback callback, int maxLatency, int maxIdleTime) {
-				maxLatency);
+		super(connectionLimiter, timeoutMonitor, ioExecutor, secureRandom,
+				backoff, callback, maxLatency, maxIdleTime);
 		this.androidExecutor = androidExecutor;
 		this.appContext = appContext;
 		this.clock = clock;
@@ -160,42 +139,17 @@ class AndroidBluetoothPlugin extends BluetoothPlugin<BluetoothServerSocket> {
 	@Override
 	void disableAdapterIfEnabledByUs() {
 		if (isAdapterEnabled() && wasEnabledByUs) {
-			cancelDiscoverability();
 			if (adapter.disable()) LOG.info("Disabling Bluetooth");
 			else LOG.info("Could not disable Bluetooth");
 			wasEnabledByUs = false;
 		}
 	}
 
-	private void cancelDiscoverability() {
-		if (adapter.getScanMode() == SCAN_MODE_CONNECTABLE_DISCOVERABLE) {
-			try {
-				Method setDiscoverableTimeout = BluetoothAdapter.class
-						.getDeclaredMethod("setDiscoverableTimeout", int.class);
-				setDiscoverableTimeout.setAccessible(true);
-				setDiscoverableTimeout.invoke(adapter, 1);
-				LOG.info("Cancelled discoverability");
-			} catch (NoSuchMethodException e) {
-				logException(LOG, WARNING, e);
-			} catch (IllegalAccessException e) {
-				logException(LOG, WARNING, e);
-			} catch (InvocationTargetException e) {
-				logException(LOG, WARNING, e);
-			}
-		}
-	}
-
 	@Override
 	void setEnabledByUs() {
 		wasEnabledByUs = true;
 	}
 
-	@Override
-	void onAdapterDisabled() {
-		super.onAdapterDisabled();
-		wasEnabledByUs = false;
-	}
-
 	@Override
 	@Nullable
 	String getBluetoothAddress() {
@@ -220,9 +174,10 @@ class AndroidBluetoothPlugin extends BluetoothPlugin<BluetoothServerSocket> {
 		return wrapSocket(ss.accept());
 	}
 
-	private DuplexTransportConnection wrapSocket(BluetoothSocket s) {
+	private DuplexTransportConnection wrapSocket(BluetoothSocket s)
-		return new AndroidBluetoothTransportConnection(this,
+			throws IOException {
-				connectionLimiter, s);
+		return new AndroidBluetoothTransportConnection(this, connectionLimiter,
+				timeoutMonitor, s);
 	}
 
 	@Override
@@ -250,8 +205,7 @@ class AndroidBluetoothPlugin extends BluetoothPlugin<BluetoothServerSocket> {
 	@Nullable
 	DuplexTransportConnection discoverAndConnect(String uuid) {
 		if (adapter == null) return null;
-		for (BluetoothDevice d : discoverDevices()) {
+		for (String address : discoverDevices()) {
-			String address = d.getAddress();
 			try {
 				if (LOG.isLoggable(INFO))
 					LOG.info("Connecting to " + scrubMacAddress(address));
@@ -267,184 +221,10 @@ class AndroidBluetoothPlugin extends BluetoothPlugin<BluetoothServerSocket> {
 		return null;
 	}
 
-	@Override
+	private Collection<String> discoverDevices() {
-	public boolean supportsDiscovery() {
+		List<String> addresses = new ArrayList<>();
-		return true;
-	}
-
-	@Override
-	public void discoverPeers(
-			List<Pair<TransportProperties, DiscoveryHandler>> properties) {
-		// Discover all nearby devices
-		List<BluetoothDevice> devices = discoverDevices();
-		if (devices.isEmpty()) {
-			LOG.info("No devices discovered");
-			return;
-		}
-
-		List<Pair<TransportProperties, DiscoveryHandler>> discovered =
-				new ArrayList<>();
-		Map<String, Pair<TransportProperties, DiscoveryHandler>> byUuid =
-				new HashMap<>();
-		Map<String, Pair<TransportProperties, DiscoveryHandler>> byAddress =
-				new HashMap<>();
-		for (Pair<TransportProperties, DiscoveryHandler> pair : properties) {
-			TransportProperties p = pair.getFirst();
-			String uuid = p.get(PROP_UUID);
-			if (!isNullOrEmpty(uuid)) {
-				byUuid.put(uuid, pair);
-				String address = p.get(PROP_ADDRESS);
-				if (!isNullOrEmpty(address)) byAddress.put(address, pair);
-			}
-		}
-
-		List<BluetoothDevice> unknown = new ArrayList<>(devices);
-		for (BluetoothDevice d : devices) {
-			Pair<TransportProperties, DiscoveryHandler> pair =
-					byAddress.remove(d.getAddress());
-			if (pair == null) {
-				// Try cached UUIDs
-				for (String uuid : getUuids(d)) {
-					pair = byUuid.remove(uuid);
-					if (pair != null) {
-						if (LOG.isLoggable(INFO)) {
-							LOG.info("Matched "
-									+ scrubMacAddress(d.getAddress())
-									+ " by cached UUID");
-						}
-						TransportProperties p =
-								new TransportProperties(pair.getFirst());
-						p.put(PROP_ADDRESS, d.getAddress());
-						discovered.add(new Pair<>(p, pair.getSecond()));
-						unknown.remove(d);
-						break;
-					}
-				}
-			} else {
-				if (LOG.isLoggable(INFO)) {
-					LOG.info("Matched " + scrubMacAddress(d.getAddress())
-							+ " by address");
-				}
-				discovered.add(pair);
-				unknown.remove(d);
-			}
-		}
-		if (unknown.isEmpty()) {
-			LOG.info("All discovered devices are known, not fetching UUIDs");
-			return;
-		}
-		// Fetch up-to-date UUIDs
-		if (LOG.isLoggable(INFO))
-			LOG.info("Fetching UUIDs for " + unknown.size() + " devices");
 		BlockingQueue<Intent> intents = new LinkedBlockingQueue<>();
-		QueueingReceiver receiver = new QueueingReceiver(intents);
+		DiscoveryReceiver receiver = new DiscoveryReceiver(intents);
-		IntentFilter filter = new IntentFilter();
-		filter.addAction(ACTION_UUID);
-		appContext.registerReceiver(receiver, filter);
-		try {
-			List<BluetoothDevice> pending = new ArrayList<>();
-			for (BluetoothDevice d : unknown) {
-				if (d.fetchUuidsWithSdp()) {
-					if (LOG.isLoggable(INFO)) {
-						LOG.info("Fetching UUIDs for "
-								+ scrubMacAddress(d.getAddress()));
-					}
-					pending.add(d);
-				} else {
-					if (LOG.isLoggable(INFO)) {
-						LOG.info("Failed to fetch UUIDs for "
-								+ scrubMacAddress(d.getAddress()));
-					}
-				}
-			}
-			long now = clock.currentTimeMillis();
-			long end = now + MAX_SERVICE_DISCOVERY_MS;
-			while (now < end && !pending.isEmpty()) {
-				Intent i = intents.poll(end - now, MILLISECONDS);
-				if (i == null) break;
-				BluetoothDevice d = requireNonNull(
-						i.getParcelableExtra(EXTRA_DEVICE));
-				if (LOG.isLoggable(INFO)) {
-					LOG.info("Fetched UUIDs for "
-							+ scrubMacAddress(d.getAddress()));
-				}
-				Set<String> uuids = getUuids(d);
-				Parcelable[] extra = i.getParcelableArrayExtra(EXTRA_UUID);
-				if (extra != null) {
-					for (Parcelable p : extra) {
-						uuids.addAll(getUuidStrings((ParcelUuid) p));
-					}
-				}
-				for (String uuid : uuids) {
-					Pair<TransportProperties, DiscoveryHandler> pair =
-							byUuid.remove(uuid);
-					if (pair != null) {
-						if (LOG.isLoggable(INFO)) {
-							LOG.info("Matched "
-									+ scrubMacAddress(d.getAddress())
-									+ " by fetched UUID");
-						}
-						TransportProperties p =
-								new TransportProperties(pair.getFirst());
-						p.put(PROP_ADDRESS, d.getAddress());
-						discovered.add(new Pair<>(p, pair.getSecond()));
-						break;
-					}
-				}
-				pending.remove(d);
-				now = clock.currentTimeMillis();
-			}
-			if (LOG.isLoggable(INFO)) {
-				if (pending.isEmpty()) {
-					LOG.info("Finished fetching UUIDs");
-				} else {
-					LOG.info("Failed to fetch UUIDs for " + pending.size()
-							+ " devices");
-				}
-			}
-		} catch (InterruptedException e) {
-			LOG.info("Interrupted while fetching UUIDs");
-			Thread.currentThread().interrupt();
-		} finally {
-			appContext.unregisterReceiver(receiver);
-		}
-
-		if (LOG.isLoggable(INFO)) {
-			LOG.info("Discovered " + discovered.size() + " contacts");
-		}
-		for (Pair<TransportProperties, DiscoveryHandler> pair : discovered) {
-			pair.getSecond().handleDevice(pair.getFirst());
-		}
-	}
-
-	private Set<String> getUuids(BluetoothDevice d) {
-		Set<String> strings = new TreeSet<>();
-		ParcelUuid[] uuids = d.getUuids();
-		if (uuids == null) return strings;
-		for (ParcelUuid u : uuids) strings.addAll(getUuidStrings(u));
-		return strings;
-	}
-
-	// Workaround for https://code.google.com/p/android/issues/detail?id=197341
-	private List<String> getUuidStrings(ParcelUuid u) {
-		UUID forwards = u.getUuid();
-		ByteBuffer buf = ByteBuffer.allocate(16);
-		buf.putLong(forwards.getLeastSignificantBits());
-		buf.putLong(forwards.getMostSignificantBits());
-		buf.rewind();
-		buf.order(LITTLE_ENDIAN);
-		UUID backwards = new UUID(buf.getLong(), buf.getLong());
-		return asList(forwards.toString(), backwards.toString());
-	}
-
-	private List<BluetoothDevice> discoverDevices() {
-		if (adapter.isDiscovering()) {
-			LOG.info("Already discovering");
-			return emptyList();
-		}
-		List<BluetoothDevice> devices = new ArrayList<>();
-		BlockingQueue<Intent> intents = new LinkedBlockingQueue<>();
-		QueueingReceiver receiver = new QueueingReceiver(intents);
 		IntentFilter filter = new IntentFilter();
 		filter.addAction(ACTION_DISCOVERY_STARTED);
 		filter.addAction(ACTION_DISCOVERY_FINISHED);
@@ -452,9 +232,8 @@ class AndroidBluetoothPlugin extends BluetoothPlugin<BluetoothServerSocket> {
 		appContext.registerReceiver(receiver, filter);
 		try {
 			if (adapter.startDiscovery()) {
-				long start = clock.currentTimeMillis();
+				long now = clock.currentTimeMillis();
-				long end = start + MAX_DEVICE_DISCOVERY_MS;
+				long end = now + MAX_DISCOVERY_MS;
-				long now = start;
 				while (now < end) {
 					Intent i = intents.poll(end - now, MILLISECONDS);
 					if (i == null) break;
@@ -463,26 +242,17 @@ class AndroidBluetoothPlugin extends BluetoothPlugin<BluetoothServerSocket> {
 						LOG.info("Discovery started");
 					} else if (ACTION_DISCOVERY_FINISHED.equals(action)) {
 						LOG.info("Discovery finished");
-						now = clock.currentTimeMillis();
+						break;
-						if (now - start < MIN_DEVICE_DISCOVERY_MS) {
-							LOG.info("Discovery finished quickly, retrying");
-							if (!adapter.startDiscovery()) {
-								LOG.info("Could not restart discovery");
-								break;
-							}
-						} else {
-							break;
-						}
 					} else if (ACTION_FOUND.equals(action)) {
-						BluetoothDevice d = requireNonNull(
+						BluetoothDevice d = i.getParcelableExtra(EXTRA_DEVICE);
-								i.getParcelableExtra(EXTRA_DEVICE));
 						// Ignore Bluetooth LE devices
 						if (SDK_INT < 18 || d.getType() != DEVICE_TYPE_LE) {
-							if (LOG.isLoggable(INFO)) {
+							String address = d.getAddress();
-								LOG.info("Discovered "
+							if (LOG.isLoggable(INFO))
-										+ scrubMacAddress(d.getAddress()));
+								LOG.info("Discovered " +
-							}
+										scrubMacAddress(address));
-							if (!devices.contains(d)) devices.add(d);
+							if (!addresses.contains(address))
+								addresses.add(address);
 						}
 					}
 					now = clock.currentTimeMillis();
@@ -498,9 +268,9 @@ class AndroidBluetoothPlugin extends BluetoothPlugin<BluetoothServerSocket> {
 			adapter.cancelDiscovery();
 			appContext.unregisterReceiver(receiver);
 		}
-		// Shuffle the devices so we don't always try the same one first
+		// Shuffle the addresses so we don't always try the same one first
-		shuffle(devices);
+		shuffle(addresses);
-		return devices;
+		return addresses;
 	}
 
 	private class BluetoothStateReceiver extends BroadcastReceiver {
@@ -521,11 +291,11 @@ class AndroidBluetoothPlugin extends BluetoothPlugin<BluetoothServerSocket> {
 		}
 	}
 
-	private static class QueueingReceiver extends BroadcastReceiver {
+	private static class DiscoveryReceiver extends BroadcastReceiver {
 
 		private final BlockingQueue<Intent> intents;
 
-		private QueueingReceiver(BlockingQueue<Intent> intents) {
+		private DiscoveryReceiver(BlockingQueue<Intent> intents) {
 			this.intents = intents;
 		}
 

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

@@ -3,6 +3,7 @@ package org.briarproject.bramble.plugin.bluetooth;
 import android.content.Context;
 
 import org.briarproject.bramble.api.event.EventBus;
+import org.briarproject.bramble.api.io.TimeoutMonitor;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.Backoff;
 import org.briarproject.bramble.api.plugin.BackoffFactory;
@@ -25,6 +26,7 @@ import static org.briarproject.bramble.api.plugin.BluetoothConstants.ID;
 public class AndroidBluetoothPluginFactory implements DuplexPluginFactory {
 
 	private static final int MAX_LATENCY = 30 * 1000; // 30 seconds
+	private static final int MAX_IDLE_TIME = 30 * 1000; // 30 seconds
 	private static final int MIN_POLLING_INTERVAL = 60 * 1000; // 1 minute
 	private static final int MAX_POLLING_INTERVAL = 10 * 60 * 1000; // 10 mins
 	private static final double BACKOFF_BASE = 1.2;
@@ -35,18 +37,20 @@ public class AndroidBluetoothPluginFactory implements DuplexPluginFactory {
 	private final SecureRandom secureRandom;
 	private final EventBus eventBus;
 	private final Clock clock;
+	private final TimeoutMonitor timeoutMonitor;
 	private final BackoffFactory backoffFactory;
 
 	public AndroidBluetoothPluginFactory(Executor ioExecutor,
 			AndroidExecutor androidExecutor, Context appContext,
 			SecureRandom secureRandom, EventBus eventBus, Clock clock,
-			BackoffFactory backoffFactory) {
+			TimeoutMonitor timeoutMonitor, BackoffFactory backoffFactory) {
 		this.ioExecutor = ioExecutor;
 		this.androidExecutor = androidExecutor;
 		this.appContext = appContext;
 		this.secureRandom = secureRandom;
 		this.eventBus = eventBus;
 		this.clock = clock;
+		this.timeoutMonitor = timeoutMonitor;
 		this.backoffFactory = backoffFactory;
 	}
 
@@ -63,12 +67,13 @@ public class AndroidBluetoothPluginFactory implements DuplexPluginFactory {
 	@Override
 	public DuplexPlugin createPlugin(PluginCallback callback) {
 		BluetoothConnectionLimiter connectionLimiter =
-				new BluetoothConnectionLimiterImpl();
+				new BluetoothConnectionLimiterImpl(eventBus, clock);
 		Backoff backoff = backoffFactory.createBackoff(MIN_POLLING_INTERVAL,
 				MAX_POLLING_INTERVAL, BACKOFF_BASE);
 		AndroidBluetoothPlugin plugin = new AndroidBluetoothPlugin(
-				connectionLimiter, ioExecutor, androidExecutor, appContext,
+				connectionLimiter, timeoutMonitor, ioExecutor, secureRandom,
-				secureRandom, clock, backoff, callback, MAX_LATENCY);
+				androidExecutor, appContext, clock, backoff,
+				callback, MAX_LATENCY, MAX_IDLE_TIME);
 		eventBus.addListener(plugin);
 		return plugin;
 	}

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

@@ -2,6 +2,7 @@ package org.briarproject.bramble.plugin.bluetooth;
 
 import android.bluetooth.BluetoothSocket;
 
+import org.briarproject.bramble.api.io.TimeoutMonitor;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.Plugin;
 import org.briarproject.bramble.api.plugin.duplex.AbstractDuplexTransportConnection;
@@ -10,24 +11,33 @@ import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
 
+import static org.briarproject.bramble.api.plugin.BluetoothConstants.PROP_ADDRESS;
+import static org.briarproject.bramble.util.AndroidUtils.isValidBluetoothAddress;
+
 @NotNullByDefault
 class AndroidBluetoothTransportConnection
 		extends AbstractDuplexTransportConnection {
 
-	private final BluetoothConnectionLimiter connectionManager;
+	private final BluetoothConnectionLimiter connectionLimiter;
 	private final BluetoothSocket socket;
+	private final InputStream in;
 
 	AndroidBluetoothTransportConnection(Plugin plugin,
-			BluetoothConnectionLimiter connectionManager,
+			BluetoothConnectionLimiter connectionLimiter,
-			BluetoothSocket socket) {
+			TimeoutMonitor timeoutMonitor, BluetoothSocket socket)
+			throws IOException {
 		super(plugin);
-		this.connectionManager = connectionManager;
+		this.connectionLimiter = connectionLimiter;
 		this.socket = socket;
+		in = timeoutMonitor.createTimeoutInputStream(
+				socket.getInputStream(), plugin.getMaxIdleTime() * 2);
+		String address = socket.getRemoteDevice().getAddress();
+		if (isValidBluetoothAddress(address)) remote.put(PROP_ADDRESS, address);
 	}
 
 	@Override
-	protected InputStream getInputStream() throws IOException {
+	protected InputStream getInputStream() {
-		return socket.getInputStream();
+		return in;
 	}
 
 	@Override
@@ -40,7 +50,7 @@ class AndroidBluetoothTransportConnection
 		try {
 			socket.close();
 		} finally {
-			connectionManager.connectionClosed(this);
+			connectionLimiter.connectionClosed(this, exception);
 		}
 	}
 }

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

@@ -9,11 +9,11 @@ import android.net.wifi.WifiManager;
 
 import org.briarproject.bramble.PoliteExecutor;
 import org.briarproject.bramble.api.event.Event;
+import org.briarproject.bramble.api.event.EventListener;
 import org.briarproject.bramble.api.network.event.NetworkStatusEvent;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.Backoff;
 import org.briarproject.bramble.api.plugin.PluginCallback;
-import org.briarproject.bramble.api.settings.Settings;
 
 import java.io.IOException;
 import java.net.InetAddress;
@@ -32,14 +32,10 @@ import static android.net.ConnectivityManager.TYPE_WIFI;
 import static android.os.Build.VERSION.SDK_INT;
 import static java.util.Collections.emptyList;
 import static java.util.Collections.singletonList;
-import static java.util.logging.Level.WARNING;
 import static java.util.logging.Logger.getLogger;
-import static org.briarproject.bramble.api.plugin.Plugin.State.ACTIVE;
-import static org.briarproject.bramble.api.plugin.Plugin.State.INACTIVE;
-import static org.briarproject.bramble.util.IoUtils.tryToClose;
 
 @NotNullByDefault
-class AndroidLanTcpPlugin extends LanTcpPlugin {
+class AndroidLanTcpPlugin extends LanTcpPlugin implements EventListener {
 
 	private static final Logger LOG =
 			getLogger(AndroidLanTcpPlugin.class.getName());
@@ -72,11 +68,16 @@ class AndroidLanTcpPlugin extends LanTcpPlugin {
 	public void start() {
 		if (used.getAndSet(true)) throw new IllegalStateException();
 		initialisePortProperty();
-		Settings settings = callback.getSettings();
+		running = true;
-		state.setStarted(settings.getBoolean(PREF_PLUGIN_ENABLE, false));
 		updateConnectionStatus();
 	}
 
+	@Override
+	public void stop() {
+		running = false;
+		tryToClose(socket);
+	}
+
 	@Override
 	protected Socket createSocket() throws IOException {
 		return socketFactory.createSocket();
@@ -129,15 +130,13 @@ class AndroidLanTcpPlugin extends LanTcpPlugin {
 
 	@Override
 	public void eventOccurred(Event e) {
-		super.eventOccurred(e);
 		if (e instanceof NetworkStatusEvent) updateConnectionStatus();
 	}
 
 	private void updateConnectionStatus() {
 		connectionStatusExecutor.execute(() -> {
-			State s = getState();
+			if (!running) return;
-			if (s != ACTIVE && s != INACTIVE) return;
+			List<InetAddress> addrs = getUsableLocalInetAddresses();
-			List<InetAddress> addrs = getLocalInetAddresses();
 			if (addrs.contains(WIFI_AP_ADDRESS)
 					|| addrs.contains(WIFI_DIRECT_AP_ADDRESS)) {
 				LOG.info("Providing wifi hotspot");
@@ -146,21 +145,15 @@ class AndroidLanTcpPlugin extends LanTcpPlugin {
 				// make outgoing connections on API 21+ if another network
 				// has internet access
 				socketFactory = SocketFactory.getDefault();
-				if (s == INACTIVE) bind();
+				if (socket == null || socket.isClosed()) bind();
 			} else if (addrs.isEmpty()) {
 				LOG.info("Not connected to wifi");
 				socketFactory = SocketFactory.getDefault();
-				// Server socket may not have been closed automatically when
+				tryToClose(socket);
-				// interface was taken down. Socket will be cleared and state
-				// updated in acceptContactConnections()
-				if (s == ACTIVE) {
-					LOG.info("Closing server socket");
-					tryToClose(state.getServerSocket(), LOG, WARNING);
-				}
 			} else {
 				LOG.info("Connected to wifi");
 				socketFactory = getSocketFactory();
-				if (s == INACTIVE) bind();
+				if (socket == null || socket.isClosed()) bind();
 			}
 		});
 	}

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

@@ -74,6 +74,7 @@ class AndroidTorPlugin extends TorPlugin {
 
 	@Override
 	protected void enableNetwork(boolean enable) throws IOException {
+		if (!running) return;
 		if (enable) wakeLock.acquire();
 		super.enableNetwork(enable);
 		if (!enable) wakeLock.release();

bramble-android/src/main/java/org/briarproject/bramble/system/AndroidLocationUtils.java

@@ -61,12 +61,12 @@ class AndroidLocationUtils implements LocationUtils {
 	private String getCountryFromPhoneNetwork() {
 		Object o = appContext.getSystemService(TELEPHONY_SERVICE);
 		TelephonyManager tm = (TelephonyManager) o;
-		return tm == null ? "" : tm.getNetworkCountryIso();
+		return tm.getNetworkCountryIso();
 	}
 
 	private String getCountryFromSimCard() {
 		Object o = appContext.getSystemService(TELEPHONY_SERVICE);
 		TelephonyManager tm = (TelephonyManager) o;
-		return tm == null ? "" : tm.getSimCountryIso();
+		return tm.getSimCountryIso();
 	}
 }

bramble-android/src/main/java/org/briarproject/bramble/util/AndroidUtils.java

@@ -71,7 +71,7 @@ public class AndroidUtils {
 		return new Pair<>("", "");
 	}
 
-	private static boolean isValidBluetoothAddress(@Nullable String address) {
+	public static boolean isValidBluetoothAddress(@Nullable String address) {
 		return !StringUtils.isNullOrEmpty(address)
 				&& BluetoothAdapter.checkBluetoothAddress(address)
 				&& !address.equals(FAKE_BLUETOOTH_ADDRESS);

bramble-android/witness.gradle

@@ -70,7 +70,7 @@ dependencyVerification {
         'org.bouncycastle:bcpkix-jdk15on:1.56:bcpkix-jdk15on-1.56.jar:7043dee4e9e7175e93e0b36f45b1ec1ecb893c5f755667e8b916eb8dd201c6ca',
         'org.bouncycastle:bcprov-jdk15on:1.56:bcprov-jdk15on-1.56.jar:963e1ee14f808ffb99897d848ddcdb28fa91ddda867eb18d303e82728f878349',
         'org.briarproject:obfs4proxy-android:0.0.11-2:obfs4proxy-android-0.0.11-2.zip:57e55cbe87aa2aac210fdbb6cd8cdeafe15f825406a08ebf77a8b787aa2c6a8a',
-        'org.briarproject:tor-android:0.3.5.9:tor-android-0.3.5.9.zip:853b0440feccd6904bd03e6b2de53a62ebcde1d58068beeadc447a7dff950bc8',
+        'org.briarproject:tor-android:0.3.5.10:tor-android-0.3.5.10.zip:edd83bf557fcff2105eaa0bdb3f607a6852ebe7360920929ae3039dd5f4774c5',
         'org.checkerframework:checker-compat-qual:2.5.3:checker-compat-qual-2.5.3.jar:d76b9afea61c7c082908023f0cbc1427fab9abd2df915c8b8a3e7a509bccbc6d',
         'org.checkerframework:checker-qual:2.5.2:checker-qual-2.5.2.jar:64b02691c8b9d4e7700f8ee2e742dce7ea2c6e81e662b7522c9ee3bf568c040a',
         'org.codehaus.groovy:groovy-all:2.4.15:groovy-all-2.4.15.jar:51d6c4e71782e85674239189499854359d380fb75e1a703756e3aaa5b98a5af0',

bramble-api/src/main/java/org/briarproject/bramble/api/account/AccountManager.java

@@ -1,5 +1,6 @@
 package org.briarproject.bramble.api.account;
 
+import org.briarproject.bramble.api.crypto.DecryptionException;
 import org.briarproject.bramble.api.crypto.SecretKey;
 import org.briarproject.bramble.api.identity.IdentityManager;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
@@ -13,7 +14,8 @@ public interface AccountManager {
 	 * Returns true if the manager has the database key. This will be false
 	 * before {@link #createAccount(String, String)} or {@link #signIn(String)}
 	 * has been called, and true after {@link #createAccount(String, String)}
-	 * or {@link #signIn(String)} has returned true, until the process exits.
+	 * or {@link #signIn(String)} has returned true, until
+	 * {@link #deleteAccount()} is called or the process exits.
 	 */
 	boolean hasDatabaseKey();
 
@@ -22,25 +24,22 @@ public interface AccountManager {
 	 * before {@link #createAccount(String, String)} or {@link #signIn(String)}
 	 * has been called, and non-null after
 	 * {@link #createAccount(String, String)} or {@link #signIn(String)} has
-	 * returned true, until the process exits.
+	 * returned true, until {@link #deleteAccount()} is called or the process
+	 * exits.
 	 */
 	@Nullable
 	SecretKey getDatabaseKey();
 
 	/**
-	 * Returns true if the encrypted database key can be loaded from disk, and
+	 * Returns true if the encrypted database key can be loaded from disk.
-	 * the database directory exists and is a directory.
 	 */
 	boolean accountExists();
 
 	/**
 	 * Creates an identity with the given name and registers it with the
 	 * {@link IdentityManager}. Creates a database key, encrypts it with the
-	 * given password and stores it on disk.
+	 * given password and stores it on disk. {@link #accountExists()} will
-	 * <p/>
+	 * return true after this method returns true.
-	 * This method does not create the database directory, so
-	 * {@link #accountExists()} will continue to return false until the
-	 * database directory is created.
 	 */
 	boolean createAccount(String name, String password);
 
@@ -54,17 +53,19 @@ public interface AccountManager {
 	 * Loads the encrypted database key from disk and decrypts it with the
 	 * given password.
 	 *
-	 * @return true if the database key was successfully loaded and decrypted.
+	 * @throws DecryptionException If the database key could not be loaded and
+	 * decrypted.
 	 */
-	boolean signIn(String password);
+	void signIn(String password) throws DecryptionException;
 
 	/**
 	 * Loads the encrypted database key from disk, decrypts it with the old
 	 * password, encrypts it with the new password, and stores it on disk,
 	 * replacing the old key.
 	 *
-	 * @return true if the database key was successfully loaded, re-encrypted
+	 * @throws DecryptionException If the database key could not be loaded and
-	 * and stored.
+	 * decrypted.
 	 */
-	boolean changePassword(String oldPassword, String newPassword);
+	void changePassword(String oldPassword, String newPassword)
+			throws DecryptionException;
 }

bramble-api/src/main/java/org/briarproject/bramble/api/crypto/CryptoComponent.java

@@ -142,16 +142,17 @@ public interface CryptoComponent {
 	/**
 	 * Decrypts and authenticates the given ciphertext that has been read from
 	 * storage. The encryption and authentication keys are derived from the
-	 * given password. Returns null if the ciphertext cannot be decrypted and
+	 * given password.
-	 * authenticated (for example, if the password is wrong).
 	 *
 	 * @param keyStrengthener Used to strengthen the password-based key. If
 	 * null, or if strengthening was not used when encrypting the ciphertext,
 	 * the password-based key will not be strengthened
+	 * @throws DecryptionException If the ciphertext cannot be decrypted and
+	 * authenticated (for example, if the password is wrong).
 	 */
-	@Nullable
 	byte[] decryptWithPassword(byte[] ciphertext, String password,
-			@Nullable KeyStrengthener keyStrengthener);
+			@Nullable KeyStrengthener keyStrengthener)
+			throws DecryptionException;
 
 	/**
 	 * Returns true if the given ciphertext was encrypted using a strengthened

bramble-api/src/main/java/org/briarproject/bramble/api/crypto/DecryptionException.java

@@ -0,0 +1,17 @@
+package org.briarproject.bramble.api.crypto;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+@NotNullByDefault
+public class DecryptionException extends Exception {
+
+	private final DecryptionResult result;
+
+	public DecryptionException(DecryptionResult result) {
+		this.result = result;
+	}
+
+	public DecryptionResult getDecryptionResult() {
+		return result;
+	}
+}

bramble-api/src/main/java/org/briarproject/bramble/api/crypto/DecryptionResult.java

@@ -0,0 +1,29 @@
+package org.briarproject.bramble.api.crypto;
+
+/**
+ * The result of a password-based decryption operation.
+ */
+public enum DecryptionResult {
+
+	/**
+	 * Decryption succeeded.
+	 */
+	SUCCESS,
+
+	/**
+	 * Decryption failed because the format of the ciphertext was invalid.
+	 */
+	INVALID_CIPHERTEXT,
+
+	/**
+	 * Decryption failed because the {@link KeyStrengthener} used for
+	 * encryption was not available for decryption.
+	 */
+	KEY_STRENGTHENER_ERROR,
+
+	/**
+	 * Decryption failed because the password used for decryption did not match
+	 * the password used for encryption.
+	 */
+	INVALID_PASSWORD
+}

bramble-api/src/main/java/org/briarproject/bramble/api/event/EventBus.java

@@ -18,8 +18,6 @@ public interface EventBus {
 	/**
 	 * Asynchronously notifies all listeners of an event. Listeners are
 	 * notified on the {@link EventExecutor}.
-	 * <p>
-	 * This method can safely be called while holding a lock.
 	 */
 	void broadcast(Event e);
 }

bramble-api/src/main/java/org/briarproject/bramble/api/io/TimeoutMonitor.java

@@ -0,0 +1,15 @@
+package org.briarproject.bramble.api.io;
+
+import java.io.InputStream;
+
+public interface TimeoutMonitor {
+
+	/**
+	 * Returns an {@link InputStream} that wraps the given stream and allows
+	 * read timeouts to be detected.
+	 *
+	 * @param timeoutMs The read timeout in milliseconds. Timeouts will be
+	 * detected eventually but are not guaranteed to be detected immediately.
+	 */
+	InputStream createTimeoutInputStream(InputStream in, long timeoutMs);
+}

bramble-api/src/main/java/org/briarproject/bramble/api/plugin/BluetoothConstants.java

@@ -8,4 +8,6 @@ public interface BluetoothConstants {
 
 	String PROP_ADDRESS = "address";
 	String PROP_UUID = "uuid";
+
+	String PREF_BT_ENABLE = "enable";
 }

bramble-api/src/main/java/org/briarproject/bramble/api/plugin/DiscoveryHandler.java

@@ -1,18 +0,0 @@
-package org.briarproject.bramble.api.plugin;
-
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.properties.TransportProperties;
-
-/**
- * An interface for handling peers discovered by transport plugins.
- */
-@NotNullByDefault
-public interface DiscoveryHandler {
-
-	/**
-	 * Handles a peer discovered by a transport plugin.
-	 *
-	 * @param p A set of properties describing the discovered peer.
-	 */
-	void handleDevice(TransportProperties p);
-}

bramble-api/src/main/java/org/briarproject/bramble/api/plugin/Plugin.java

@@ -3,55 +3,12 @@ package org.briarproject.bramble.api.plugin;
 import org.briarproject.bramble.api.Pair;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.properties.TransportProperties;
-import org.briarproject.bramble.api.settings.SettingsManager;
 
-import java.util.List;
+import java.util.Collection;
 
 @NotNullByDefault
 public interface Plugin {
 
-	enum State {
-
-		/**
-		 * The plugin has not finished starting or has been stopped.
-		 */
-		STARTING_STOPPING,
-
-		/**
-		 * The plugin is disabled by settings. Use {@link #getReasonsDisabled()}
-		 * to find out which settings are responsible.
-		 */
-		DISABLED,
-
-		/**
-		 * The plugin is being enabled and can't yet make or receive
-		 * connections.
-		 */
-		ENABLING,
-
-		/**
-		 * The plugin is enabled and can make or receive connections.
-		 */
-		ACTIVE,
-
-		/**
-		 * The plugin is enabled but can't make or receive connections
-		 */
-		INACTIVE
-	}
-
-	/**
-	 * The string for the boolean preference
-	 * to use with the {@link SettingsManager} to enable or disable the plugin.
-	 */
-	String PREF_PLUGIN_ENABLE = "enable";
-
-	/**
-	 * Reason flag returned by {@link #getReasonsDisabled()} to indicate that
-	 * the plugin has been disabled by the user.
-	 */
-	int REASON_USER = 1;
-
 	/**
 	 * Returns the plugin's transport identifier.
 	 */
@@ -78,18 +35,9 @@ public interface Plugin {
 	void stop() throws PluginException;
 
 	/**
-	 * Returns the current state of the plugin.
+	 * Returns true if the plugin is running.
 	 */
-	State getState();
+	boolean isRunning();
-
-	/**
-	 * Returns a set of flags indicating why the plugin is
-	 * {@link State#DISABLED disabled}, or 0 if the plugin is not disabled.
-	 * <p>
-	 * The flags used are plugin-specific, except the generic flag
-	 * {@link #REASON_USER}, which may be used by any plugin.
-	 */
-	int getReasonsDisabled();
 
 	/**
 	 * Returns true if the plugin should be polled periodically to attempt to
@@ -106,5 +54,6 @@ public interface Plugin {
 	 * Attempts to create connections using the given transport properties,
 	 * passing any created connections to the corresponding handlers.
 	 */
-	void poll(List<Pair<TransportProperties, ConnectionHandler>> properties);
+	void poll(Collection<Pair<TransportProperties, ConnectionHandler>>
+			properties);
 }

bramble-api/src/main/java/org/briarproject/bramble/api/plugin/PluginCallback.java

@@ -1,10 +1,6 @@
 package org.briarproject.bramble.api.plugin;
 
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.plugin.Plugin.State;
-import org.briarproject.bramble.api.plugin.event.TransportActiveEvent;
-import org.briarproject.bramble.api.plugin.event.TransportInactiveEvent;
-import org.briarproject.bramble.api.plugin.event.TransportStateEvent;
 import org.briarproject.bramble.api.properties.TransportProperties;
 import org.briarproject.bramble.api.settings.Settings;
 
@@ -36,17 +32,12 @@ public interface PluginCallback extends ConnectionHandler {
 	void mergeLocalProperties(TransportProperties p);
 
 	/**
-	 * Informs the callback of the plugin's current state.
+	 * Signals that the transport is enabled.
-	 * <p>
-	 * If the current state is different from the previous state, the callback
-	 * will broadcast a {@link TransportStateEvent}. If the current state is
-	 * {@link State#ACTIVE} and the previous state was not
-	 * {@link State#ACTIVE}, the callback will broadcast a
-	 * {@link TransportActiveEvent}. If the current state is not
-	 * {@link State#ACTIVE} and the previous state was {@link State#ACTIVE},
-	 * the callback will broadcast a {@link TransportInactiveEvent}.
-	 * <p>
-	 * This method can safely be called while holding a lock.
 	 */
-	void pluginStateChanged(State state);
+	void transportEnabled();
+
+	/**
+	 * Signals that the transport is disabled.
+	 */
+	void transportDisabled();
 }

bramble-api/src/main/java/org/briarproject/bramble/api/plugin/PluginManager.java

@@ -41,17 +41,4 @@ public interface PluginManager {
 	 * Returns any duplex plugins that support rendezvous.
 	 */
 	Collection<DuplexPlugin> getRendezvousPlugins();
-
-	/**
-	 * Enables or disables the plugin
-	 * identified by the given {@link TransportId}.
-	 * <p>
-	 * Note that this applies the change asynchronously
-	 * and there are no order guarantees.
-	 * <p>
-	 * If no plugin with the given {@link TransportId} is registered,
-	 * this is a no-op.
-	 */
-	void setPluginEnabled(TransportId t, boolean enabled);
-
 }

bramble-api/src/main/java/org/briarproject/bramble/api/plugin/TorConstants.java

@@ -21,21 +21,6 @@ public interface TorConstants {
 	int PREF_TOR_NETWORK_AUTOMATIC = 0;
 	int PREF_TOR_NETWORK_WITHOUT_BRIDGES = 1;
 	int PREF_TOR_NETWORK_WITH_BRIDGES = 2;
-	// TODO: Remove when settings migration code is removed
 	int PREF_TOR_NETWORK_NEVER = 3;
 
-	/**
-	 * Reason flag returned by {@link Plugin#getReasonsDisabled()}.
-	 */
-	int REASON_BATTERY = 2;
-
-	/**
-	 * Reason flag returned by {@link Plugin#getReasonsDisabled()}.
-	 */
-	int REASON_MOBILE_DATA = 4;
-
-	/**
-	 * Reason flag returned by {@link Plugin#getReasonsDisabled()}.
-	 */
-	int REASON_COUNTRY_BLOCKED = 8;
 }

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

@@ -4,6 +4,7 @@ import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.Plugin;
 import org.briarproject.bramble.api.plugin.TransportConnectionReader;
 import org.briarproject.bramble.api.plugin.TransportConnectionWriter;
+import org.briarproject.bramble.api.properties.TransportProperties;
 
 import java.io.IOException;
 import java.io.InputStream;
@@ -14,6 +15,8 @@ import java.util.concurrent.atomic.AtomicBoolean;
 public abstract class AbstractDuplexTransportConnection
 		implements DuplexTransportConnection {
 
+	protected final TransportProperties remote = new TransportProperties();
+
 	private final Plugin plugin;
 	private final Reader reader;
 	private final Writer writer;
@@ -44,6 +47,11 @@ public abstract class AbstractDuplexTransportConnection
 		return writer;
 	}
 
+	@Override
+	public TransportProperties getRemoteProperties() {
+		return remote;
+	}
+
 	private class Reader implements TransportConnectionReader {
 
 		@Override

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

@@ -1,18 +1,14 @@
 package org.briarproject.bramble.api.plugin.duplex;
 
-import org.briarproject.bramble.api.Pair;
 import org.briarproject.bramble.api.data.BdfList;
 import org.briarproject.bramble.api.keyagreement.KeyAgreementListener;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.ConnectionHandler;
-import org.briarproject.bramble.api.plugin.DiscoveryHandler;
 import org.briarproject.bramble.api.plugin.Plugin;
 import org.briarproject.bramble.api.properties.TransportProperties;
 import org.briarproject.bramble.api.rendezvous.KeyMaterialSource;
 import org.briarproject.bramble.api.rendezvous.RendezvousEndpoint;
 
-import java.util.List;
-
 import javax.annotation.Nullable;
 
 /**
@@ -62,16 +58,4 @@ public interface DuplexPlugin extends Plugin {
 	@Nullable
 	RendezvousEndpoint createRendezvousEndpoint(KeyMaterialSource k,
 			boolean alice, ConnectionHandler incoming);
-
-	/**
-	 * Returns true if the plugin supports peer discovery.
-	 */
-	boolean supportsDiscovery();
-
-	/**
-	 * Attempts to discover peers using the given transport properties, passing
-	 * any discovered peers to the corresponding handlers.
-	 */
-	void discoverPeers(List<Pair<TransportProperties, DiscoveryHandler>>
-			properties);
 }

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

@@ -3,6 +3,7 @@ package org.briarproject.bramble.api.plugin.duplex;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.TransportConnectionReader;
 import org.briarproject.bramble.api.plugin.TransportConnectionWriter;
+import org.briarproject.bramble.api.properties.TransportProperties;
 
 /**
  * An interface for reading and writing data over a duplex transport. The
@@ -23,4 +24,10 @@ public interface DuplexTransportConnection {
 	 * for writing to the connection.
 	 */
 	TransportConnectionWriter getWriter();
+
+	/**
+	 * Returns a possibly empty set of {@link TransportProperties} describing
+	 * the remote peer.
+	 */
+	TransportProperties getRemoteProperties();
 }

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

@@ -2,22 +2,20 @@ package org.briarproject.bramble.api.plugin.event;
 
 import org.briarproject.bramble.api.event.Event;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.plugin.Plugin.State;
 import org.briarproject.bramble.api.plugin.TransportId;
 
 import javax.annotation.concurrent.Immutable;
 
 /**
- * An event that is broadcast when a plugin enters the {@link State#ACTIVE}
+ * An event that is broadcast when a transport is disabled.
- * state.
  */
 @Immutable
 @NotNullByDefault
-public class TransportActiveEvent extends Event {
+public class TransportDisabledEvent extends Event {
 
 	private final TransportId transportId;
 
-	public TransportActiveEvent(TransportId transportId) {
+	public TransportDisabledEvent(TransportId transportId) {
 		this.transportId = transportId;
 	}
 

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

@@ -2,22 +2,20 @@ package org.briarproject.bramble.api.plugin.event;
 
 import org.briarproject.bramble.api.event.Event;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.plugin.Plugin.State;
 import org.briarproject.bramble.api.plugin.TransportId;
 
 import javax.annotation.concurrent.Immutable;
 
 /**
- * An event that is broadcast when a plugin leaves the {@link State#ACTIVE}
+ * An event that is broadcast when a transport is enabled.
- * state.
  */
 @Immutable
 @NotNullByDefault
-public class TransportInactiveEvent extends Event {
+public class TransportEnabledEvent extends Event {
 
 	private final TransportId transportId;
 
-	public TransportInactiveEvent(TransportId transportId) {
+	public TransportEnabledEvent(TransportId transportId) {
 		this.transportId = transportId;
 	}
 

bramble-api/src/main/java/org/briarproject/bramble/api/properties/TransportPropertyConstants.java

@@ -11,4 +11,28 @@ public interface TransportPropertyConstants {
 	 * The maximum length of a property's key or value in UTF-8 bytes.
 	 */
 	int MAX_PROPERTY_LENGTH = 100;
+
+	/**
+	 * Message metadata key for the transport ID of a local or remote update,
+	 * as a BDF string.
+	 */
+	String MSG_KEY_TRANSPORT_ID = "transportId";
+
+	/**
+	 * Message metadata key for the version number of a local or remote update,
+	 * as a BDF long.
+	 */
+	String MSG_KEY_VERSION = "version";
+
+	/**
+	 * Message metadata key for whether an update is local or remote, as a BDF
+	 * boolean.
+	 */
+	String MSG_KEY_LOCAL = "local";
+
+	/**
+	 * Group metadata key for any discovered transport properties of the
+	 * contact, as a BDF dictionary.
+	 */
+	String GROUP_KEY_DISCOVERED = "discovered";
 }

bramble-api/src/main/java/org/briarproject/bramble/api/properties/TransportPropertyManager.java

@@ -34,6 +34,14 @@ public interface TransportPropertyManager {
 	void addRemoteProperties(Transaction txn, ContactId c,
 			Map<TransportId, TransportProperties> props) throws DbException;
 
+	/**
+	 * Stores the given properties discovered from an incoming transport
+	 * connection. They will be overridden by any properties received while
+	 * adding the contact or synced from the contact.
+	 */
+	void addRemotePropertiesFromConnection(ContactId c, TransportId t,
+			TransportProperties props) throws DbException;
+
 	/**
 	 * Returns the local transport properties for all transports.
 	 */

bramble-api/src/main/java/org/briarproject/bramble/api/sync/SyncSessionFactory.java

@@ -2,6 +2,7 @@ package org.briarproject.bramble.api.sync;
 
 import org.briarproject.bramble.api.contact.ContactId;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.plugin.TransportId;
 import org.briarproject.bramble.api.transport.StreamWriter;
 
 import java.io.InputStream;
@@ -11,9 +12,9 @@ public interface SyncSessionFactory {
 
 	SyncSession createIncomingSession(ContactId c, InputStream in);
 
-	SyncSession createSimplexOutgoingSession(ContactId c, int maxLatency,
+	SyncSession createSimplexOutgoingSession(ContactId c, TransportId t,
-			StreamWriter streamWriter);
+			int maxLatency, StreamWriter streamWriter);
 
-	SyncSession createDuplexOutgoingSession(ContactId c, int maxLatency,
+	SyncSession createDuplexOutgoingSession(ContactId c, TransportId t,
-			int maxIdleTime, StreamWriter streamWriter);
+			int maxLatency, int maxIdleTime, StreamWriter streamWriter);
 }

bramble-api/src/main/java/org/briarproject/bramble/api/sync/event/CloseSyncConnectionsEvent.java

@@ -1,32 +1,26 @@
-package org.briarproject.bramble.api.plugin.event;
+package org.briarproject.bramble.api.sync.event;
 
 import org.briarproject.bramble.api.event.Event;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.plugin.Plugin.State;
 import org.briarproject.bramble.api.plugin.TransportId;
 
 import javax.annotation.concurrent.Immutable;
 
 /**
- * An event that is broadcast when the {@link State state} of a plugin changes.
+ * An event that is broadcast when all sync connections using a given
+ * transport should be closed.
  */
 @Immutable
 @NotNullByDefault
-public class TransportStateEvent extends Event {
+public class CloseSyncConnectionsEvent extends Event {
 
 	private final TransportId transportId;
-	private final State state;
 
-	public TransportStateEvent(TransportId transportId, State state) {
+	public CloseSyncConnectionsEvent(TransportId transportId) {
 		this.transportId = transportId;
-		this.state = state;
 	}
 
 	public TransportId getTransportId() {
 		return transportId;
 	}
-
-	public State getState() {
-		return state;
-	}
 }

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

@@ -117,4 +117,10 @@ public class IoUtils {
 			throw new IOException(e);
 		}
 	}
+
+	public static boolean isNonEmptyDirectory(File f) {
+		if (!f.isDirectory()) return false;
+		File[] children = f.listFiles();
+		return children != null && children.length > 0;
+	}
 }

bramble-core/src/main/java/org/briarproject/bramble/BrambleCoreModule.java

@@ -9,6 +9,7 @@ import org.briarproject.bramble.db.DatabaseExecutorModule;
 import org.briarproject.bramble.db.DatabaseModule;
 import org.briarproject.bramble.event.EventModule;
 import org.briarproject.bramble.identity.IdentityModule;
+import org.briarproject.bramble.io.IoModule;
 import org.briarproject.bramble.keyagreement.KeyAgreementModule;
 import org.briarproject.bramble.lifecycle.LifecycleModule;
 import org.briarproject.bramble.plugin.PluginModule;
@@ -35,6 +36,7 @@ import dagger.Module;
 		DatabaseExecutorModule.class,
 		EventModule.class,
 		IdentityModule.class,
+		IoModule.class,
 		KeyAgreementModule.class,
 		LifecycleModule.class,
 		PluginModule.class,

bramble-core/src/main/java/org/briarproject/bramble/account/AccountManagerImpl.java

@@ -2,6 +2,7 @@ package org.briarproject.bramble.account;
 
 import org.briarproject.bramble.api.account.AccountManager;
 import org.briarproject.bramble.api.crypto.CryptoComponent;
+import org.briarproject.bramble.api.crypto.DecryptionException;
 import org.briarproject.bramble.api.crypto.KeyStrengthener;
 import org.briarproject.bramble.api.crypto.SecretKey;
 import org.briarproject.bramble.api.db.DatabaseConfig;
@@ -17,6 +18,7 @@ import java.io.FileInputStream;
 import java.io.FileOutputStream;
 import java.io.IOException;
 import java.io.InputStreamReader;
+import java.nio.charset.Charset;
 import java.util.logging.Logger;
 
 import javax.annotation.Nullable;
@@ -24,6 +26,7 @@ import javax.annotation.concurrent.GuardedBy;
 import javax.inject.Inject;
 
 import static java.util.logging.Level.WARNING;
+import static org.briarproject.bramble.api.crypto.DecryptionResult.INVALID_CIPHERTEXT;
 import static org.briarproject.bramble.util.LogUtils.logException;
 import static org.briarproject.bramble.util.StringUtils.fromHexString;
 import static org.briarproject.bramble.util.StringUtils.toHexString;
@@ -95,7 +98,7 @@ class AccountManagerImpl implements AccountManager {
 		}
 		try {
 			BufferedReader reader = new BufferedReader(new InputStreamReader(
-					new FileInputStream(f), "UTF-8"));
+					new FileInputStream(f), Charset.forName("UTF-8")));
 			String key = reader.readLine();
 			reader.close();
 			return key;
@@ -147,7 +150,7 @@ class AccountManagerImpl implements AccountManager {
 	@GuardedBy("stateChangeLock")
 	private void writeDbKeyToFile(String key, File f) throws IOException {
 		FileOutputStream out = new FileOutputStream(f);
-		out.write(key.getBytes("UTF-8"));
+		out.write(key.getBytes(Charset.forName("UTF-8")));
 		out.flush();
 		out.close();
 	}
@@ -155,8 +158,7 @@ class AccountManagerImpl implements AccountManager {
 	@Override
 	public boolean accountExists() {
 		synchronized (stateChangeLock) {
-			return loadEncryptedDatabaseKey() != null
+			return loadEncryptedDatabaseKey() != null;
-					&& databaseConfig.getDatabaseDirectory().isDirectory();
 		}
 	}
 
@@ -193,31 +195,24 @@ class AccountManagerImpl implements AccountManager {
 	}
 
 	@Override
-	public boolean signIn(String password) {
+	public void signIn(String password) throws DecryptionException {
 		synchronized (stateChangeLock) {
-			SecretKey key = loadAndDecryptDatabaseKey(password);
+			databaseKey = loadAndDecryptDatabaseKey(password);
-			if (key == null) return false;
-			databaseKey = key;
-			return true;
 		}
 	}
 
 	@GuardedBy("stateChangeLock")
-	@Nullable
+	private SecretKey loadAndDecryptDatabaseKey(String password)
-	private SecretKey loadAndDecryptDatabaseKey(String password) {
+			throws DecryptionException {
 		String hex = loadEncryptedDatabaseKey();
 		if (hex == null) {
 			LOG.warning("Failed to load encrypted database key");
-			return null;
+			throw new DecryptionException(INVALID_CIPHERTEXT);
 		}
 		byte[] ciphertext = fromHexString(hex);
 		KeyStrengthener keyStrengthener = databaseConfig.getKeyStrengthener();
 		byte[] plaintext = crypto.decryptWithPassword(ciphertext, password,
 				keyStrengthener);
-		if (plaintext == null) {
-			LOG.info("Failed to decrypt database key");
-			return null;
-		}
 		SecretKey key = new SecretKey(plaintext);
 		// If the DB key was encrypted with a weak key and a key strengthener
 		// is now available, re-encrypt the DB key with a strengthened key
@@ -230,10 +225,11 @@ class AccountManagerImpl implements AccountManager {
 	}
 
 	@Override
-	public boolean changePassword(String oldPassword, String newPassword) {
+	public void changePassword(String oldPassword, String newPassword)
+			throws DecryptionException {
 		synchronized (stateChangeLock) {
 			SecretKey key = loadAndDecryptDatabaseKey(oldPassword);
-			return key != null && encryptAndStoreDatabaseKey(key, newPassword);
+			encryptAndStoreDatabaseKey(key, newPassword);
 		}
 	}
 }

bramble-core/src/main/java/org/briarproject/bramble/crypto/CryptoComponentImpl.java

@@ -7,6 +7,7 @@ import net.i2p.crypto.eddsa.KeyPairGenerator;
 import org.briarproject.bramble.api.crypto.AgreementPrivateKey;
 import org.briarproject.bramble.api.crypto.AgreementPublicKey;
 import org.briarproject.bramble.api.crypto.CryptoComponent;
+import org.briarproject.bramble.api.crypto.DecryptionException;
 import org.briarproject.bramble.api.crypto.KeyPair;
 import org.briarproject.bramble.api.crypto.KeyParser;
 import org.briarproject.bramble.api.crypto.KeyStrengthener;
@@ -39,6 +40,9 @@ import static java.lang.System.arraycopy;
 import static java.util.logging.Level.INFO;
 import static org.briarproject.bramble.api.crypto.CryptoConstants.KEY_TYPE_AGREEMENT;
 import static org.briarproject.bramble.api.crypto.CryptoConstants.KEY_TYPE_SIGNATURE;
+import static org.briarproject.bramble.api.crypto.DecryptionResult.INVALID_CIPHERTEXT;
+import static org.briarproject.bramble.api.crypto.DecryptionResult.INVALID_PASSWORD;
+import static org.briarproject.bramble.api.crypto.DecryptionResult.KEY_STRENGTHENER_ERROR;
 import static org.briarproject.bramble.util.ByteUtils.INT_32_BYTES;
 import static org.briarproject.bramble.util.LogUtils.logDuration;
 import static org.briarproject.bramble.util.LogUtils.now;
@@ -359,16 +363,17 @@ class CryptoComponentImpl implements CryptoComponent {
 	}
 
 	@Override
-	@Nullable
 	public byte[] decryptWithPassword(byte[] input, String password,
-			@Nullable KeyStrengthener keyStrengthener) {
+			@Nullable KeyStrengthener keyStrengthener)
+			throws DecryptionException {
 		AuthenticatedCipher cipher = new XSalsa20Poly1305AuthenticatedCipher();
 		int macBytes = cipher.getMacBytes();
 		// The input contains the format version, salt, cost parameter, IV,
 		// ciphertext and MAC
 		if (input.length < 1 + PBKDF_SALT_BYTES + INT_32_BYTES
-				+ STORAGE_IV_BYTES + macBytes)
+				+ STORAGE_IV_BYTES + macBytes) {
-			return null; // Invalid input
+			throw new DecryptionException(INVALID_CIPHERTEXT);
+		}
 		int inputOff = 0;
 		// Format version
 		byte formatVersion = input[inputOff];
@@ -376,7 +381,7 @@ class CryptoComponentImpl implements CryptoComponent {
 		// Check whether we support this format version
 		if (formatVersion != PBKDF_FORMAT_SCRYPT &&
 				formatVersion != PBKDF_FORMAT_SCRYPT_STRENGTHENED) {
-			return null;
+			throw new DecryptionException(INVALID_CIPHERTEXT);
 		}
 		// Salt
 		byte[] salt = new byte[PBKDF_SALT_BYTES];
@@ -385,8 +390,9 @@ class CryptoComponentImpl implements CryptoComponent {
 		// Cost parameter
 		long cost = ByteUtils.readUint32(input, inputOff);
 		inputOff += INT_32_BYTES;
-		if (cost < 2 || cost > Integer.MAX_VALUE)
+		if (cost < 2 || cost > Integer.MAX_VALUE) {
-			return null; // Invalid cost parameter
+			throw new DecryptionException(INVALID_CIPHERTEXT);
+		}
 		// IV
 		byte[] iv = new byte[STORAGE_IV_BYTES];
 		arraycopy(input, inputOff, iv, 0, iv.length);
@@ -394,8 +400,10 @@ class CryptoComponentImpl implements CryptoComponent {
 		// Derive the decryption key from the password
 		SecretKey key = passwordBasedKdf.deriveKey(password, salt, (int) cost);
 		if (formatVersion == PBKDF_FORMAT_SCRYPT_STRENGTHENED) {
-			if (keyStrengthener == null || !keyStrengthener.isInitialised())
+			if (keyStrengthener == null || !keyStrengthener.isInitialised()) {
-				return null; // Can't derive the same strengthened key
+				// Can't derive the same strengthened key
+				throw new DecryptionException(KEY_STRENGTHENER_ERROR);
+			}
 			key = keyStrengthener.strengthenKey(key);
 		}
 		// Initialise the cipher
@@ -411,7 +419,7 @@ class CryptoComponentImpl implements CryptoComponent {
 			cipher.process(input, inputOff, inputLen, output, 0);
 			return output;
 		} catch (GeneralSecurityException e) {
-			return null; // Invalid ciphertext
+			throw new DecryptionException(INVALID_PASSWORD);
 		}
 	}
 

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

@@ -25,6 +25,7 @@ import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
 import static java.util.logging.Logger.getLogger;
 import static org.briarproject.bramble.db.JdbcUtils.tryToClose;
+import static org.briarproject.bramble.util.IoUtils.isNonEmptyDirectory;
 import static org.briarproject.bramble.util.LogUtils.logFileOrDir;
 
 /**
@@ -69,8 +70,9 @@ class H2Database extends JdbcDatabase {
 			LOG.info("Contents of account directory before opening DB:");
 			logFileOrDir(LOG, INFO, dir.getParentFile());
 		}
-		boolean reopen = !dir.mkdirs();
+		boolean reopen = isNonEmptyDirectory(dir);
 		if (LOG.isLoggable(INFO)) LOG.info("Reopening DB: " + reopen);
+		if (!reopen && dir.mkdirs()) LOG.info("Created database directory");
 		super.open("org.h2.Driver", reopen, key, listener);
 		if (LOG.isLoggable(INFO)) {
 			LOG.info("Contents of account directory after opening DB:");

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

@@ -20,9 +20,11 @@ import java.util.logging.Logger;
 import javax.annotation.Nullable;
 import javax.inject.Inject;
 
+import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
 import static java.util.logging.Logger.getLogger;
 import static org.briarproject.bramble.db.JdbcUtils.tryToClose;
+import static org.briarproject.bramble.util.IoUtils.isNonEmptyDirectory;
 
 /**
  * Contains all the HSQLDB-specific code for the database.
@@ -64,7 +66,10 @@ class HyperSqlDatabase extends JdbcDatabase {
 	public boolean open(SecretKey key, @Nullable MigrationListener listener)
 			throws DbException {
 		this.key = key;
-		boolean reopen = !config.getDatabaseDirectory().mkdirs();
+		File dir = config.getDatabaseDirectory();
+		boolean reopen = isNonEmptyDirectory(dir);
+		if (LOG.isLoggable(INFO)) LOG.info("Reopening DB: " + reopen);
+		if (!reopen && dir.mkdirs()) LOG.info("Created database directory");
 		super.open("org.hsqldb.jdbc.JDBCDriver", reopen, key, listener);
 		return reopen;
 	}

bramble-core/src/main/java/org/briarproject/bramble/io/IoModule.java

@@ -0,0 +1,18 @@
+package org.briarproject.bramble.io;
+
+import org.briarproject.bramble.api.io.TimeoutMonitor;
+
+import javax.inject.Singleton;
+
+import dagger.Module;
+import dagger.Provides;
+
+@Module
+public class IoModule {
+
+	@Provides
+	@Singleton
+	TimeoutMonitor provideTimeoutMonitor(TimeoutMonitorImpl timeoutMonitor) {
+		return timeoutMonitor;
+	}
+}

bramble-core/src/main/java/org/briarproject/bramble/io/TimeoutInputStream.java

@@ -0,0 +1,104 @@
+package org.briarproject.bramble.io;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.system.Clock;
+
+import java.io.IOException;
+import java.io.InputStream;
+
+import javax.annotation.concurrent.GuardedBy;
+
+@NotNullByDefault
+class TimeoutInputStream extends InputStream {
+
+	private final Clock clock;
+	private final InputStream in;
+	private final long timeoutMs;
+	private final CloseListener listener;
+	private final Object lock = new Object();
+	@GuardedBy("lock")
+	private long readStartedMs = -1;
+
+	TimeoutInputStream(Clock clock, InputStream in, long timeoutMs,
+			CloseListener listener) {
+		this.clock = clock;
+		this.in = in;
+		this.timeoutMs = timeoutMs;
+		this.listener = listener;
+	}
+
+	@Override
+	public int read() throws IOException {
+		synchronized (lock) {
+			readStartedMs = clock.currentTimeMillis();
+		}
+		int input = in.read();
+		synchronized (lock) {
+			readStartedMs = -1;
+		}
+		return input;
+	}
+
+	@Override
+	public int read(byte[] b) throws IOException {
+		return read(b, 0, b.length);
+	}
+
+	@Override
+	public int read(byte[] b, int off, int len) throws IOException {
+		synchronized (lock) {
+			readStartedMs = clock.currentTimeMillis();
+		}
+		int read = in.read(b, off, len);
+		synchronized (lock) {
+			readStartedMs = -1;
+		}
+		return read;
+	}
+
+	@Override
+	public void close() throws IOException {
+		try {
+			in.close();
+		} finally {
+			listener.onClose(this);
+		}
+	}
+
+	@Override
+	public int available() throws IOException {
+		return in.available();
+	}
+
+	@Override
+	public void mark(int readlimit) {
+		in.mark(readlimit);
+	}
+
+	@Override
+	public boolean markSupported() {
+		return in.markSupported();
+	}
+
+	@Override
+	public void reset() throws IOException {
+		in.reset();
+	}
+
+	@Override
+	public long skip(long n) throws IOException {
+		return in.skip(n);
+	}
+
+	boolean hasTimedOut() {
+		synchronized (lock) {
+			return readStartedMs != -1 &&
+					clock.currentTimeMillis() - readStartedMs > timeoutMs;
+		}
+	}
+
+	interface CloseListener {
+
+		void onClose(TimeoutInputStream closed);
+	}
+}

bramble-core/src/main/java/org/briarproject/bramble/io/TimeoutMonitorImpl.java

@@ -0,0 +1,96 @@
+package org.briarproject.bramble.io;
+
+import org.briarproject.bramble.api.io.TimeoutMonitor;
+import org.briarproject.bramble.api.lifecycle.IoExecutor;
+import org.briarproject.bramble.api.system.Clock;
+import org.briarproject.bramble.api.system.Scheduler;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.Executor;
+import java.util.concurrent.Future;
+import java.util.concurrent.ScheduledExecutorService;
+import java.util.logging.Logger;
+
+import javax.annotation.concurrent.GuardedBy;
+import javax.inject.Inject;
+
+import static java.util.concurrent.TimeUnit.MILLISECONDS;
+import static java.util.concurrent.TimeUnit.SECONDS;
+import static java.util.logging.Level.INFO;
+import static java.util.logging.Logger.getLogger;
+import static org.briarproject.bramble.util.LogUtils.logException;
+
+class TimeoutMonitorImpl implements TimeoutMonitor {
+
+	private static final Logger LOG =
+			getLogger(TimeoutMonitorImpl.class.getName());
+
+	private static final long CHECK_INTERVAL_MS = SECONDS.toMillis(10);
+
+	private final ScheduledExecutorService scheduler;
+	private final Executor ioExecutor;
+	private final Clock clock;
+	private final Object lock = new Object();
+	@GuardedBy("lock")
+	private final List<TimeoutInputStream> streams = new ArrayList<>();
+
+	@GuardedBy("lock")
+	private Future<?> task = null;
+
+	@Inject
+	TimeoutMonitorImpl(@Scheduler ScheduledExecutorService scheduler,
+			@IoExecutor Executor ioExecutor, Clock clock) {
+		this.scheduler = scheduler;
+		this.ioExecutor = ioExecutor;
+		this.clock = clock;
+	}
+
+	@Override
+	public InputStream createTimeoutInputStream(InputStream in,
+			long timeoutMs) {
+		TimeoutInputStream stream = new TimeoutInputStream(clock, in,
+				timeoutMs, this::removeStream);
+		synchronized (lock) {
+			if (streams.isEmpty()) {
+				task = scheduler.scheduleWithFixedDelay(this::checkTimeouts,
+						CHECK_INTERVAL_MS, CHECK_INTERVAL_MS, MILLISECONDS);
+			}
+			streams.add(stream);
+		}
+		return stream;
+	}
+
+	private void removeStream(TimeoutInputStream stream) {
+		Future<?> toCancel = null;
+		synchronized (lock) {
+			if (streams.remove(stream) && streams.isEmpty()) {
+				toCancel = task;
+				task = null;
+			}
+		}
+		if (toCancel != null) toCancel.cancel(false);
+	}
+
+	@Scheduler
+	private void checkTimeouts() {
+		ioExecutor.execute(() -> {
+			List<TimeoutInputStream> snapshot;
+			synchronized (lock) {
+				snapshot = new ArrayList<>(streams);
+			}
+			for (TimeoutInputStream stream : snapshot) {
+				if (stream.hasTimedOut()) {
+					LOG.info("Input stream has timed out");
+					try {
+						stream.close();
+					} catch (IOException e) {
+						logException(LOG, INFO, e);
+					}
+				}
+			}
+		});
+	}
+}

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

@@ -15,6 +15,8 @@ import org.briarproject.bramble.api.plugin.TransportConnectionReader;
 import org.briarproject.bramble.api.plugin.TransportConnectionWriter;
 import org.briarproject.bramble.api.plugin.TransportId;
 import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
+import org.briarproject.bramble.api.properties.TransportProperties;
+import org.briarproject.bramble.api.properties.TransportPropertyManager;
 import org.briarproject.bramble.api.sync.SyncSession;
 import org.briarproject.bramble.api.sync.SyncSessionFactory;
 import org.briarproject.bramble.api.transport.KeyManager;
@@ -52,6 +54,7 @@ class ConnectionManagerImpl implements ConnectionManager {
 	private final HandshakeManager handshakeManager;
 	private final ContactExchangeManager contactExchangeManager;
 	private final ConnectionRegistry connectionRegistry;
+	private final TransportPropertyManager transportPropertyManager;
 
 	@Inject
 	ConnectionManagerImpl(@IoExecutor Executor ioExecutor,
@@ -60,7 +63,8 @@ class ConnectionManagerImpl implements ConnectionManager {
 			SyncSessionFactory syncSessionFactory,
 			HandshakeManager handshakeManager,
 			ContactExchangeManager contactExchangeManager,
-			ConnectionRegistry connectionRegistry) {
+			ConnectionRegistry connectionRegistry,
+			TransportPropertyManager transportPropertyManager) {
 		this.ioExecutor = ioExecutor;
 		this.keyManager = keyManager;
 		this.streamReaderFactory = streamReaderFactory;
@@ -69,6 +73,7 @@ class ConnectionManagerImpl implements ConnectionManager {
 		this.handshakeManager = handshakeManager;
 		this.contactExchangeManager = contactExchangeManager;
 		this.connectionRegistry = connectionRegistry;
+		this.transportPropertyManager = transportPropertyManager;
 	}
 
 	@Override
@@ -125,8 +130,8 @@ class ConnectionManagerImpl implements ConnectionManager {
 			TransportConnectionWriter w) throws IOException {
 		StreamWriter streamWriter = streamWriterFactory.createStreamWriter(
 				w.getOutputStream(), ctx);
-		ContactId c = requireNonNull(ctx.getContactId());
+		return syncSessionFactory.createSimplexOutgoingSession(
-		return syncSessionFactory.createSimplexOutgoingSession(c,
+				requireNonNull(ctx.getContactId()), ctx.getTransportId(),
 				w.getMaxLatency(), streamWriter);
 	}
 
@@ -134,8 +139,8 @@ class ConnectionManagerImpl implements ConnectionManager {
 			TransportConnectionWriter w) throws IOException {
 		StreamWriter streamWriter = streamWriterFactory.createStreamWriter(
 				w.getOutputStream(), ctx);
-		ContactId c = requireNonNull(ctx.getContactId());
+		return syncSessionFactory.createDuplexOutgoingSession(
-		return syncSessionFactory.createDuplexOutgoingSession(c,
+				requireNonNull(ctx.getContactId()), ctx.getTransportId(),
 				w.getMaxLatency(), w.getMaxIdleTime(), streamWriter);
 	}
 
@@ -269,6 +274,7 @@ class ConnectionManagerImpl implements ConnectionManager {
 		private final TransportId transportId;
 		private final TransportConnectionReader reader;
 		private final TransportConnectionWriter writer;
+		private final TransportProperties remote;
 
 		@Nullable
 		private volatile SyncSession outgoingSession = null;
@@ -278,6 +284,7 @@ class ConnectionManagerImpl implements ConnectionManager {
 			this.transportId = transportId;
 			reader = connection.getReader();
 			writer = connection.getWriter();
+			remote = connection.getRemoteProperties();
 		}
 
 		@Override
@@ -313,13 +320,16 @@ class ConnectionManagerImpl implements ConnectionManager {
 			// Start the outgoing session on another thread
 			ioExecutor.execute(() -> runOutgoingSession(contactId));
 			try {
+				// Store any transport properties discovered from the connection
+				transportPropertyManager.addRemotePropertiesFromConnection(
+						contactId, transportId, remote);
 				// Create and run the incoming session
 				createIncomingSession(ctx, reader).run();
 				reader.dispose(false, true);
 				// Interrupt the outgoing session so it finishes cleanly
 				SyncSession out = outgoingSession;
 				if (out != null) out.interrupt();
-			} catch (IOException e) {
+			} catch (DbException | IOException e) {
 				logException(LOG, WARNING, e);
 				onReadError(true);
 			} finally {
@@ -375,6 +385,7 @@ class ConnectionManagerImpl implements ConnectionManager {
 		private final TransportId transportId;
 		private final TransportConnectionReader reader;
 		private final TransportConnectionWriter writer;
+		private final TransportProperties remote;
 
 		@Nullable
 		private volatile SyncSession outgoingSession = null;
@@ -385,6 +396,7 @@ class ConnectionManagerImpl implements ConnectionManager {
 			this.transportId = transportId;
 			reader = connection.getReader();
 			writer = connection.getWriter();
+			remote = connection.getRemoteProperties();
 		}
 
 		@Override
@@ -461,13 +473,16 @@ class ConnectionManagerImpl implements ConnectionManager {
 			connectionRegistry.registerConnection(contactId, transportId,
 					false);
 			try {
+				// Store any transport properties discovered from the connection
+				transportPropertyManager.addRemotePropertiesFromConnection(
+						contactId, transportId, remote);
 				// Create and run the incoming session
 				createIncomingSession(ctx, reader).run();
 				reader.dispose(false, true);
 				// Interrupt the outgoing session so it finishes cleanly
 				SyncSession out = outgoingSession;
 				if (out != null) out.interrupt();
-			} catch (IOException e) {
+			} catch (DbException | IOException e) {
 				logException(LOG, WARNING, e);
 				onReadError();
 			} finally {

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

@@ -8,7 +8,6 @@ import org.briarproject.bramble.api.lifecycle.ServiceException;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.ConnectionManager;
 import org.briarproject.bramble.api.plugin.Plugin;
-import org.briarproject.bramble.api.plugin.Plugin.State;
 import org.briarproject.bramble.api.plugin.PluginCallback;
 import org.briarproject.bramble.api.plugin.PluginConfig;
 import org.briarproject.bramble.api.plugin.PluginException;
@@ -19,9 +18,8 @@ import org.briarproject.bramble.api.plugin.TransportId;
 import org.briarproject.bramble.api.plugin.duplex.DuplexPlugin;
 import org.briarproject.bramble.api.plugin.duplex.DuplexPluginFactory;
 import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
-import org.briarproject.bramble.api.plugin.event.TransportActiveEvent;
+import org.briarproject.bramble.api.plugin.event.TransportDisabledEvent;
-import org.briarproject.bramble.api.plugin.event.TransportInactiveEvent;
+import org.briarproject.bramble.api.plugin.event.TransportEnabledEvent;
-import org.briarproject.bramble.api.plugin.event.TransportStateEvent;
 import org.briarproject.bramble.api.plugin.simplex.SimplexPlugin;
 import org.briarproject.bramble.api.plugin.simplex.SimplexPluginFactory;
 import org.briarproject.bramble.api.properties.TransportProperties;
@@ -38,7 +36,6 @@ import java.util.concurrent.CopyOnWriteArrayList;
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.Executor;
 import java.util.concurrent.atomic.AtomicBoolean;
-import java.util.concurrent.atomic.AtomicReference;
 import java.util.logging.Logger;
 
 import javax.annotation.concurrent.ThreadSafe;
@@ -48,9 +45,6 @@ import static java.util.logging.Level.FINE;
 import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
 import static java.util.logging.Logger.getLogger;
-import static org.briarproject.bramble.api.plugin.Plugin.PREF_PLUGIN_ENABLE;
-import static org.briarproject.bramble.api.plugin.Plugin.State.ACTIVE;
-import static org.briarproject.bramble.api.plugin.Plugin.State.STARTING_STOPPING;
 import static org.briarproject.bramble.util.LogUtils.logDuration;
 import static org.briarproject.bramble.util.LogUtils.logException;
 import static org.briarproject.bramble.util.LogUtils.now;
@@ -183,26 +177,6 @@ class PluginManagerImpl implements PluginManager, Service {
 		return supported;
 	}
 
-	@Override
-	public void setPluginEnabled(TransportId t, boolean enabled) {
-		Plugin plugin = plugins.get(t);
-		if (plugin == null) return;
-
-		Settings s = new Settings();
-		s.putBoolean(PREF_PLUGIN_ENABLE, enabled);
-		ioExecutor.execute(() -> mergeSettings(s, t.getString()));
-	}
-
-	private void mergeSettings(Settings s, String namespace) {
-		try {
-			long start = now();
-			settingsManager.mergeSettings(s, namespace);
-			logDuration(LOG, "Merging settings", start);
-		} catch (DbException e) {
-			logException(LOG, WARNING, e);
-		}
-	}
-
 	private class PluginStarter implements Runnable {
 
 		private final Plugin plugin;
@@ -276,8 +250,7 @@ class PluginManagerImpl implements PluginManager, Service {
 	private class Callback implements PluginCallback {
 
 		private final TransportId id;
-		private final AtomicReference<State> state =
+		private final AtomicBoolean enabled = new AtomicBoolean(false);
-				new AtomicReference<>(STARTING_STOPPING);
 
 		private Callback(TransportId id) {
 			this.id = id;
@@ -305,7 +278,11 @@ class PluginManagerImpl implements PluginManager, Service {
 
 		@Override
 		public void mergeSettings(Settings s) {
-			PluginManagerImpl.this.mergeSettings(s, id.getString());
+			try {
+				settingsManager.mergeSettings(s, id.getString());
+			} catch (DbException e) {
+				logException(LOG, WARNING, e);
+			}
 		}
 
 		@Override
@@ -318,20 +295,15 @@ class PluginManagerImpl implements PluginManager, Service {
 		}
 
 		@Override
-		public void pluginStateChanged(State newState) {
+		public void transportEnabled() {
-			State oldState = state.getAndSet(newState);
+			if (!enabled.getAndSet(true))
-			if (newState != oldState) {
+				eventBus.broadcast(new TransportEnabledEvent(id));
-				if (LOG.isLoggable(INFO)) {
+		}
-					LOG.info(id + " changed from state " + oldState
+
-							+ " to " + newState);
+		@Override
-				}
+		public void transportDisabled() {
-				eventBus.broadcast(new TransportStateEvent(id, newState));
+			if (enabled.getAndSet(false))
-				if (newState == ACTIVE) {
+				eventBus.broadcast(new TransportDisabledEvent(id));
-					eventBus.broadcast(new TransportActiveEvent(id));
-				} else if (oldState == ACTIVE) {
-					eventBus.broadcast(new TransportInactiveEvent(id));
-				}
-			}
 		}
 
 		@Override

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

@@ -11,7 +11,6 @@ import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.ConnectionHandler;
 import org.briarproject.bramble.api.plugin.ConnectionManager;
 import org.briarproject.bramble.api.plugin.ConnectionRegistry;
-import org.briarproject.bramble.api.plugin.DiscoveryHandler;
 import org.briarproject.bramble.api.plugin.Plugin;
 import org.briarproject.bramble.api.plugin.PluginManager;
 import org.briarproject.bramble.api.plugin.TransportConnectionReader;
@@ -21,8 +20,8 @@ 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.TransportActiveEvent;
+import org.briarproject.bramble.api.plugin.event.TransportDisabledEvent;
-import org.briarproject.bramble.api.plugin.event.TransportInactiveEvent;
+import org.briarproject.bramble.api.plugin.event.TransportEnabledEvent;
 import org.briarproject.bramble.api.plugin.simplex.SimplexPlugin;
 import org.briarproject.bramble.api.properties.TransportProperties;
 import org.briarproject.bramble.api.properties.TransportPropertyManager;
@@ -33,7 +32,6 @@ import java.security.SecureRandom;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.HashMap;
-import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.concurrent.Executor;
@@ -108,13 +106,13 @@ class PollerImpl implements Poller, EventListener {
 			ConnectionOpenedEvent c = (ConnectionOpenedEvent) e;
 			// Reschedule polling, the polling interval may have decreased
 			reschedule(c.getTransportId());
-		} else if (e instanceof TransportActiveEvent) {
+		} else if (e instanceof TransportEnabledEvent) {
-			TransportActiveEvent t = (TransportActiveEvent) e;
+			TransportEnabledEvent t = (TransportEnabledEvent) e;
-			// Poll the newly activated transport
+			// Poll the newly enabled transport
 			pollNow(t.getTransportId());
-		} else if (e instanceof TransportInactiveEvent) {
+		} else if (e instanceof TransportDisabledEvent) {
-			TransportInactiveEvent t = (TransportInactiveEvent) e;
+			TransportDisabledEvent t = (TransportDisabledEvent) e;
-			// Cancel polling for the deactivated transport
+			// Cancel polling for the disabled transport
 			cancel(t.getTransportId());
 		}
 	}
@@ -212,20 +210,18 @@ class PollerImpl implements Poller, EventListener {
 	@IoExecutor
 	private void poll(Plugin p) {
 		TransportId t = p.getId();
-		if (LOG.isLoggable(INFO)) LOG.info("Polling " + t);
+		if (LOG.isLoggable(INFO)) LOG.info("Polling plugin " + t);
 		try {
 			Map<ContactId, TransportProperties> remote =
 					transportPropertyManager.getRemoteProperties(t);
 			Collection<ContactId> connected =
 					connectionRegistry.getConnectedContacts(t);
-			List<Pair<TransportProperties, ConnectionHandler>> properties =
+			Collection<Pair<TransportProperties, ConnectionHandler>>
-					new ArrayList<>();
+					properties = new ArrayList<>();
 			for (Entry<ContactId, TransportProperties> e : remote.entrySet()) {
 				ContactId c = e.getKey();
-				if (!connected.contains(c)) {
+				if (!connected.contains(c))
-					ConnHandler handler = new ConnHandler(c, t);
+					properties.add(new Pair<>(e.getValue(), new Handler(c, t)));
-					properties.add(new Pair<>(e.getValue(), handler));
-				}
 			}
 			if (!properties.isEmpty()) p.poll(properties);
 		} catch (DbException e) {
@@ -233,30 +229,6 @@ class PollerImpl implements Poller, EventListener {
 		}
 	}
 
-	@IoExecutor
-	private void discover(DuplexPlugin p) {
-		TransportId t = p.getId();
-		if (LOG.isLoggable(INFO)) LOG.info("Discovering peers for " + t);
-		try {
-			Map<ContactId, TransportProperties> remote =
-					transportPropertyManager.getRemoteProperties(t);
-			Collection<ContactId> connected =
-					connectionRegistry.getConnectedContacts(t);
-			List<Pair<TransportProperties, DiscoveryHandler>> properties =
-					new ArrayList<>();
-			for (Entry<ContactId, TransportProperties> e : remote.entrySet()) {
-				ContactId c = e.getKey();
-				if (!connected.contains(c)) {
-					DiscoHandler handler = new DiscoHandler(c, p);
-					properties.add(new Pair<>(e.getValue(), handler));
-				}
-			}
-			if (!properties.isEmpty()) p.discoverPeers(properties);
-		} catch (DbException e) {
-			logException(LOG, WARNING, e);
-		}
-	}
-
 	private class ScheduledPollTask {
 
 		private final PollTask task;
@@ -296,23 +268,16 @@ class PollerImpl implements Poller, EventListener {
 			int delay = plugin.getPollingInterval();
 			if (randomiseNext) delay = (int) (delay * random.nextDouble());
 			schedule(plugin, delay, false);
-			// FIXME: Revert
+			poll(plugin);
-			if (plugin instanceof DuplexPlugin) {
-				DuplexPlugin d = (DuplexPlugin) plugin;
-				if (d.supportsDiscovery()) discover(d);
-				else poll(d);
-			} else {
-				poll(plugin);
-			}
 		}
 	}
 
-	private class ConnHandler implements ConnectionHandler {
+	private class Handler implements ConnectionHandler {
 
 		private final ContactId contactId;
 		private final TransportId transportId;
 
-		private ConnHandler(ContactId contactId, TransportId transportId) {
+		private Handler(ContactId contactId, TransportId transportId) {
 			this.contactId = contactId;
 			this.transportId = transportId;
 		}
@@ -335,27 +300,4 @@ class PollerImpl implements Poller, EventListener {
 					transportId, w);
 		}
 	}
-
-	private class DiscoHandler implements DiscoveryHandler {
-
-		private final ContactId contactId;
-		private final DuplexPlugin plugin;
-
-		private DiscoHandler(ContactId contactId, DuplexPlugin plugin) {
-			this.contactId = contactId;
-			this.plugin = plugin;
-		}
-
-		@Override
-		public void handleDevice(TransportProperties p) {
-			LOG.info("Discovered contact via " + plugin.getId());
-			ioExecutor.execute(() -> {
-				DuplexTransportConnection c = plugin.createConnection(p);
-				if (c != null) {
-					connectionManager.manageOutgoingConnection(contactId,
-							plugin.getId(), c);
-				}
-			});
-		}
-	}
 }

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

@@ -3,9 +3,30 @@ package org.briarproject.bramble.plugin.bluetooth;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
 
+import static java.util.concurrent.TimeUnit.DAYS;
+import static java.util.concurrent.TimeUnit.MINUTES;
+import static java.util.concurrent.TimeUnit.SECONDS;
+
 @NotNullByDefault
 interface BluetoothConnectionLimiter {
 
+	/**
+	 * How long a connection must remain open before it's considered stable.
+	 */
+	long STABILITY_PERIOD_MS = SECONDS.toMillis(90);
+
+	/**
+	 * The minimum interval between attempts to raise the connection limit.
+	 * This is longer than {@link #STABILITY_PERIOD_MS} so we don't start
+	 * another attempt before knowing the outcome of the last one.
+	 */
+	long MIN_ATTEMPT_INTERVAL_MS = MINUTES.toMillis(2);
+
+	/**
+	 * The maximum interval between attempts to raise the connection limit.
+	 */
+	long MAX_ATTEMPT_INTERVAL_MS = DAYS.toMillis(2);
+
 	/**
 	 * Informs the limiter that key agreement has started.
 	 */
@@ -23,12 +44,12 @@ interface BluetoothConnectionLimiter {
 	boolean canOpenContactConnection();
 
 	/**
-	 * Informs the limiter that a contact connection has been opened. The
+	 * Informs the limiter that a contact connection has been opened.
-	 * limiter may close the new connection if key agreement is in progress.
 	 * <p/>
-	 * Returns false if the limiter has closed the new connection.
+	 * Returns true if the connection is allowed.
 	 */
-	boolean contactConnectionOpened(DuplexTransportConnection conn);
+	boolean contactConnectionOpened(DuplexTransportConnection conn,
+			boolean incoming);
 
 	/**
 	 * Informs the limiter that a key agreement connection has been opened.
@@ -37,11 +58,13 @@ interface BluetoothConnectionLimiter {
 
 	/**
 	 * Informs the limiter that the given connection has been closed.
+	 *
+	 * @param exception True if the connection was closed due to an exception.
 	 */
-	void connectionClosed(DuplexTransportConnection conn);
+	void connectionClosed(DuplexTransportConnection conn, boolean exception);
 
 	/**
-	 * Informs the limiter that all connections have been closed.
+	 * Informs the limiter that the Bluetooth adapter has been disabled.
 	 */
-	void allConnectionsClosed();
+	void bluetoothDisabled();
 }

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

@@ -1,46 +1,59 @@
 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.duplex.DuplexTransportConnection;
+import org.briarproject.bramble.api.sync.event.CloseSyncConnectionsEvent;
+import org.briarproject.bramble.api.system.Clock;
 
-import java.io.IOException;
+import java.util.Iterator;
-import java.util.ArrayList;
 import java.util.LinkedList;
 import java.util.List;
 import java.util.logging.Logger;
 
+import javax.annotation.concurrent.GuardedBy;
 import javax.annotation.concurrent.ThreadSafe;
+import javax.inject.Inject;
 
+import static java.lang.Math.min;
 import static java.util.logging.Level.INFO;
-import static java.util.logging.Level.WARNING;
+import static java.util.logging.Logger.getLogger;
-import static org.briarproject.bramble.util.LogUtils.logException;
+import static org.briarproject.bramble.api.plugin.BluetoothConstants.ID;
 
 @NotNullByDefault
 @ThreadSafe
 class BluetoothConnectionLimiterImpl implements BluetoothConnectionLimiter {
 
 	private static final Logger LOG =
-			Logger.getLogger(BluetoothConnectionLimiterImpl.class.getName());
+			getLogger(BluetoothConnectionLimiterImpl.class.getName());
+
+	private final EventBus eventBus;
+	private final Clock clock;
 
 	private final Object lock = new Object();
-	// The following are locking: lock
+	@GuardedBy("lock")
-	private final LinkedList<DuplexTransportConnection> connections =
+	private final List<ConnectionRecord> connections = new LinkedList<>();
-			new LinkedList<>();
+	@GuardedBy("lock")
 	private boolean keyAgreementInProgress = false;
+	@GuardedBy("lock")
+	private int connectionLimit = 1;
+	@GuardedBy("lock")
+	private long timeOfLastAttempt = 0,
+			attemptInterval = MIN_ATTEMPT_INTERVAL_MS;
+
+	@Inject
+	BluetoothConnectionLimiterImpl(EventBus eventBus, Clock clock) {
+		this.eventBus = eventBus;
+		this.clock = clock;
+	}
 
 	@Override
 	public void keyAgreementStarted() {
-		List<DuplexTransportConnection> close;
 		synchronized (lock) {
 			keyAgreementInProgress = true;
-			close = new ArrayList<>(connections);
-			connections.clear();
 		}
-		if (LOG.isLoggable(INFO)) {
+		LOG.info("Key agreement started");
-			LOG.info("Key agreement started, closing " + close.size() +
+		eventBus.broadcast(new CloseSyncConnectionsEvent(ID));
-					" connections");
-		}
-		for (DuplexTransportConnection conn : close) tryToClose(conn);
 	}
 
 	@Override
@@ -55,62 +68,128 @@ class BluetoothConnectionLimiterImpl implements BluetoothConnectionLimiter {
 	public boolean canOpenContactConnection() {
 		synchronized (lock) {
 			if (keyAgreementInProgress) {
-				LOG.info("Can't open contact connection during key agreement");
+				LOG.info("Refusing contact connection during key agreement");
 				return false;
 			} else {
-				LOG.info("Can open contact connection");
+				long now = clock.currentTimeMillis();
-				return true;
+				return isContactConnectionAllowedByLimit(now);
 			}
 		}
 	}
 
 	@Override
-	public boolean contactConnectionOpened(DuplexTransportConnection conn) {
+	public boolean contactConnectionOpened(DuplexTransportConnection conn,
-		boolean accept = true;
+			boolean incoming) {
 		synchronized (lock) {
 			if (keyAgreementInProgress) {
 				LOG.info("Refusing contact connection during key agreement");
-				accept = false;
+				return false;
 			} else {
-				LOG.info("Accepting contact connection");
+				long now = clock.currentTimeMillis();
-				connections.add(conn);
+				if (incoming || isContactConnectionAllowedByLimit(now)) {
+					connections.add(new ConnectionRecord(conn, now));
+					if (!incoming && connections.size() > connectionLimit) {
+						LOG.info("Attempting to raise connection limit");
+						timeOfLastAttempt = now;
+					}
+					return true;
+				} else {
+					return false;
+				}
 			}
 		}
-		if (!accept) tryToClose(conn);
-		return accept;
 	}
 
 	@Override
 	public void keyAgreementConnectionOpened(DuplexTransportConnection conn) {
 		synchronized (lock) {
 			LOG.info("Accepting key agreement connection");
-			connections.add(conn);
+			connections.add(
-		}
+					new ConnectionRecord(conn, clock.currentTimeMillis()));
-	}
-
-	private void tryToClose(DuplexTransportConnection conn) {
-		try {
-			conn.getWriter().dispose(false);
-			conn.getReader().dispose(false, false);
-		} catch (IOException e) {
-			logException(LOG, WARNING, e);
 		}
 	}
 
 	@Override
-	public void connectionClosed(DuplexTransportConnection conn) {
+	public void connectionClosed(DuplexTransportConnection conn,
+			boolean exception) {
 		synchronized (lock) {
-			connections.remove(conn);
+			Iterator<ConnectionRecord> it = connections.iterator();
+			while (it.hasNext()) {
+				if (it.next().connection == conn) {
+					long now = clock.currentTimeMillis();
+					if (exception) connectionFailed(now);
+					else considerRaisingConnectionLimit(now);
+					it.remove();
+					break;
+				}
+			}
 			if (LOG.isLoggable(INFO))
 				LOG.info("Connection closed, " + connections.size() + " open");
 		}
 	}
 
 	@Override
-	public void allConnectionsClosed() {
+	public void bluetoothDisabled() {
 		synchronized (lock) {
+			LOG.info("Bluetooth disabled");
+			considerRaisingConnectionLimit(clock.currentTimeMillis());
 			connections.clear();
-			LOG.info("All connections closed");
+		}
+	}
+
+	@GuardedBy("lock")
+	private boolean isContactConnectionAllowedByLimit(long now) {
+		considerRaisingConnectionLimit(now);
+		if (connections.size() > connectionLimit) {
+			LOG.info("Refusing contact connection, above limit");
+			return false;
+		} else if (connections.size() < connectionLimit) {
+			LOG.info("Allowing contact connection, below limit");
+			return true;
+		} else if (now - timeOfLastAttempt >= attemptInterval) {
+			LOG.info("Allowing contact connection, at limit");
+			return true;
+		} else {
+			LOG.info("Refusing contact connection, at limit");
+			return false;
+		}
+	}
+
+	@GuardedBy("lock")
+	private void considerRaisingConnectionLimit(long now) {
+		int stable = 0;
+		for (ConnectionRecord rec : connections) {
+			if (now - rec.timeOpened >= STABILITY_PERIOD_MS) stable++;
+		}
+		if (stable > connectionLimit) {
+			LOG.info("Raising connection limit");
+			connectionLimit = stable;
+			attemptInterval = MIN_ATTEMPT_INTERVAL_MS;
+		}
+		if (LOG.isLoggable(INFO)) {
+			LOG.info(stable + " connections are stable, limit is "
+					+ connectionLimit);
+		}
+	}
+
+	@GuardedBy("lock")
+	private void connectionFailed(long now) {
+		if (connections.size() > connectionLimit &&
+				now - timeOfLastAttempt < STABILITY_PERIOD_MS) {
+			LOG.info("Connection failed above limit, increasing interval");
+			attemptInterval = min(attemptInterval * 2, MAX_ATTEMPT_INTERVAL_MS);
+		}
+	}
+
+	private static final class ConnectionRecord {
+
+		private final DuplexTransportConnection connection;
+		private final long timeOpened;
+
+		private ConnectionRecord(DuplexTransportConnection connection,
+				long timeOpened) {
+			this.connection = connection;
+			this.timeOpened = timeOpened;
 		}
 	}
 }

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

@@ -5,17 +5,15 @@ import org.briarproject.bramble.api.Pair;
 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.io.TimeoutMonitor;
 import org.briarproject.bramble.api.keyagreement.KeyAgreementConnection;
 import org.briarproject.bramble.api.keyagreement.KeyAgreementListener;
 import org.briarproject.bramble.api.keyagreement.event.KeyAgreementListeningEvent;
 import org.briarproject.bramble.api.keyagreement.event.KeyAgreementStoppedListeningEvent;
-import org.briarproject.bramble.api.lifecycle.IoExecutor;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.bramble.api.plugin.Backoff;
 import org.briarproject.bramble.api.plugin.ConnectionHandler;
-import org.briarproject.bramble.api.plugin.DiscoveryHandler;
 import org.briarproject.bramble.api.plugin.PluginCallback;
 import org.briarproject.bramble.api.plugin.PluginException;
 import org.briarproject.bramble.api.plugin.TransportId;
@@ -32,28 +30,23 @@ import org.briarproject.bramble.api.settings.event.SettingsUpdatedEvent;
 
 import java.io.IOException;
 import java.security.SecureRandom;
-import java.util.List;
+import java.util.Collection;
 import java.util.UUID;
 import java.util.concurrent.Executor;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.logging.Logger;
 
 import javax.annotation.Nullable;
-import javax.annotation.concurrent.GuardedBy;
-import javax.annotation.concurrent.ThreadSafe;
 
 import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
 import static java.util.logging.Logger.getLogger;
 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.api.plugin.Plugin.State.ACTIVE;
-import static org.briarproject.bramble.api.plugin.Plugin.State.DISABLED;
-import static org.briarproject.bramble.api.plugin.Plugin.State.INACTIVE;
-import static org.briarproject.bramble.api.plugin.Plugin.State.STARTING_STOPPING;
 import static org.briarproject.bramble.util.LogUtils.logException;
 import static org.briarproject.bramble.util.PrivacyUtils.scrubMacAddress;
 import static org.briarproject.bramble.util.StringUtils.isNullOrEmpty;
@@ -68,17 +61,18 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 			getLogger(BluetoothPlugin.class.getName());
 
 	final BluetoothConnectionLimiter connectionLimiter;
+	final TimeoutMonitor timeoutMonitor;
 
 	private final Executor ioExecutor;
 	private final SecureRandom secureRandom;
 	private final Backoff backoff;
 	private final PluginCallback callback;
-	private final int maxLatency;
+	private final int maxLatency, maxIdleTime;
 	private final AtomicBoolean used = new AtomicBoolean(false);
 
-	protected final PluginState state = new PluginState();
+	private volatile boolean running = false, contactConnections = false;
-
 	private volatile String contactConnectionsUuid = null;
+	private volatile SS socket = null;
 
 	abstract void initialiseAdapter() throws IOException;
 
@@ -113,32 +107,31 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 	abstract DuplexTransportConnection discoverAndConnect(String uuid);
 
 	BluetoothPlugin(BluetoothConnectionLimiter connectionLimiter,
-			Executor ioExecutor, SecureRandom secureRandom,
+			TimeoutMonitor timeoutMonitor, Executor ioExecutor,
-			Backoff backoff, PluginCallback callback, int maxLatency) {
+			SecureRandom secureRandom, Backoff backoff,
+			PluginCallback callback, int maxLatency, int maxIdleTime) {
 		this.connectionLimiter = connectionLimiter;
+		this.timeoutMonitor = timeoutMonitor;
 		this.ioExecutor = ioExecutor;
 		this.secureRandom = secureRandom;
 		this.backoff = backoff;
 		this.callback = callback;
 		this.maxLatency = maxLatency;
+		this.maxIdleTime = maxIdleTime;
 	}
 
 	void onAdapterEnabled() {
 		LOG.info("Bluetooth enabled");
 		// We may not have been able to get the local address before
 		ioExecutor.execute(this::updateProperties);
-		if (getState() == INACTIVE) bind();
+		if (shouldAllowContactConnections()) bind();
 	}
 
 	void onAdapterDisabled() {
 		LOG.info("Bluetooth disabled");
-		connectionLimiter.allConnectionsClosed();
+		tryToClose(socket);
-		// The server socket may not have been closed automatically
+		connectionLimiter.bluetoothDisabled();
-		SS ss = state.clearServerSocket();
+		callback.transportDisabled();
-		if (ss != null) {
-			LOG.info("Closing server socket");
-			tryToClose(ss);
-		}
 	}
 
 	@Override
@@ -153,31 +146,37 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 
 	@Override
 	public int getMaxIdleTime() {
-		// Bluetooth detects dead connections so we don't need keepalives
+		return maxIdleTime;
-		return Integer.MAX_VALUE;
 	}
 
 	@Override
 	public void start() throws PluginException {
 		if (used.getAndSet(true)) throw new IllegalStateException();
-		Settings settings = callback.getSettings();
-		boolean enabledByUser = settings.getBoolean(PREF_PLUGIN_ENABLE, false);
-		state.setStarted(enabledByUser);
 		try {
 			initialiseAdapter();
 		} catch (IOException e) {
 			throw new PluginException(e);
 		}
 		updateProperties();
-		if (enabledByUser) {
+		running = true;
+		loadSettings(callback.getSettings());
+		if (shouldAllowContactConnections()) {
 			if (isAdapterEnabled()) bind();
 			else enableAdapter();
 		}
 	}
 
+	private void loadSettings(Settings settings) {
+		contactConnections = settings.getBoolean(PREF_BT_ENABLE, false);
+	}
+
+	private boolean shouldAllowContactConnections() {
+		return contactConnections;
+	}
+
 	private void bind() {
 		ioExecutor.execute(() -> {
-			if (getState() != INACTIVE) return;
+			if (!isRunning() || !shouldAllowContactConnections()) return;
 			// Bind a server socket to accept connections from contacts
 			SS ss;
 			try {
@@ -186,13 +185,14 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 				logException(LOG, WARNING, e);
 				return;
 			}
-			if (!state.setServerSocket(ss)) {
+			if (!isRunning() || !shouldAllowContactConnections()) {
-				LOG.info("Closing redundant server socket");
 				tryToClose(ss);
 				return;
 			}
+			socket = ss;
 			backoff.reset();
-			acceptContactConnections(ss);
+			callback.transportEnabled();
+			acceptContactConnections();
 		});
 	}
 
@@ -221,39 +221,47 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 		if (changed) callback.mergeLocalProperties(p);
 	}
 
-	private void acceptContactConnections(SS ss) {
+	private void acceptContactConnections() {
 		while (true) {
 			DuplexTransportConnection conn;
 			try {
-				conn = acceptConnection(ss);
+				conn = acceptConnection(socket);
 			} catch (IOException e) {
-				// This is expected when the server socket is closed
+				// This is expected when the socket is closed
-				LOG.info("Server socket closed");
+				if (LOG.isLoggable(INFO)) LOG.info(e.toString());
-				state.clearServerSocket();
 				return;
 			}
 			LOG.info("Connection received");
-			backoff.reset();
+			if (connectionLimiter.contactConnectionOpened(conn, true)) {
-			if (connectionLimiter.contactConnectionOpened(conn))
+				backoff.reset();
 				callback.handleConnection(conn);
+			} else {
+				tryToClose(conn);
+			}
+			if (!running) return;
+		}
+	}
+
+	private void tryToClose(DuplexTransportConnection conn) {
+		try {
+			conn.getWriter().dispose(false);
+			conn.getReader().dispose(false, false);
+		} catch (IOException e) {
+			logException(LOG, WARNING, e);
 		}
 	}
 
 	@Override
 	public void stop() {
-		SS ss = state.setStopped();
+		running = false;
-		tryToClose(ss);
+		tryToClose(socket);
+		callback.transportDisabled();
 		disableAdapterIfEnabledByUs();
 	}
 
 	@Override
-	public State getState() {
+	public boolean isRunning() {
-		return state.getState();
+		return running && isAdapterEnabled();
-	}
-
-	@Override
-	public int getReasonsDisabled() {
-		return state.getReasonsDisabled();
 	}
 
 	@Override
@@ -267,9 +275,9 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 	}
 
 	@Override
-	public void poll(
+	public void poll(Collection<Pair<TransportProperties, ConnectionHandler>>
-			List<Pair<TransportProperties, ConnectionHandler>> properties) {
+			properties) {
-		if (getState() != ACTIVE) return;
+		if (!isRunning() || !shouldAllowContactConnections()) return;
 		backoff.increment();
 		for (Pair<TransportProperties, ConnectionHandler> p : properties) {
 			connect(p.getFirst(), p.getSecond());
@@ -282,13 +290,10 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 		String uuid = p.get(PROP_UUID);
 		if (isNullOrEmpty(uuid)) return;
 		ioExecutor.execute(() -> {
-			if (getState() != ACTIVE) return;
-			if (!connectionLimiter.canOpenContactConnection()) return;
 			DuplexTransportConnection d = createConnection(p);
 			if (d != null) {
 				backoff.reset();
-				if (connectionLimiter.contactConnectionOpened(d))
+				h.handleConnection(d);
-					h.handleConnection(d);
 			}
 		});
 	}
@@ -326,7 +331,7 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 
 	@Override
 	public DuplexTransportConnection createConnection(TransportProperties p) {
-		if (getState() != ACTIVE) return null;
+		if (!isRunning() || !shouldAllowContactConnections()) return null;
 		if (!connectionLimiter.canOpenContactConnection()) return null;
 		String address = p.get(PROP_ADDRESS);
 		if (isNullOrEmpty(address)) return null;
@@ -334,8 +339,12 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 		if (isNullOrEmpty(uuid)) return null;
 		DuplexTransportConnection conn = connect(address, uuid);
 		if (conn == null) return null;
-		// TODO: Why don't we reset the backoff here?
+		if (connectionLimiter.contactConnectionOpened(conn, false)) {
-		return connectionLimiter.contactConnectionOpened(conn) ? conn : null;
+			return conn;
+		} else {
+			tryToClose(conn);
+			return null;
+		}
 	}
 
 	@Override
@@ -345,7 +354,7 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 
 	@Override
 	public KeyAgreementListener createKeyAgreementListener(byte[] commitment) {
-		if (getState() != ACTIVE) return null;
+		if (!isRunning()) 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);
@@ -357,7 +366,7 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 			logException(LOG, WARNING, e);
 			return null;
 		}
-		if (getState() != ACTIVE) {
+		if (!isRunning()) {
 			tryToClose(ss);
 			return null;
 		}
@@ -371,7 +380,7 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 	@Override
 	public DuplexTransportConnection createKeyAgreementConnection(
 			byte[] commitment, BdfList descriptor) {
-		if (getState() != ACTIVE) return null;
+		if (!isRunning()) return null;
 		// No truncation necessary because COMMIT_LENGTH = 16
 		String uuid = UUID.nameUUIDFromBytes(commitment).toString();
 		DuplexTransportConnection conn;
@@ -412,17 +421,6 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 		throw new UnsupportedOperationException();
 	}
 
-	@Override
-	public boolean supportsDiscovery() {
-		return false;
-	}
-
-	@Override
-	public void discoverPeers(
-			List<Pair<TransportProperties, DiscoveryHandler>> properties) {
-		throw new UnsupportedOperationException();
-	}
-
 	@Override
 	public void eventOccurred(Event e) {
 		if (e instanceof EnableBluetoothEvent) {
@@ -442,17 +440,17 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 		}
 	}
 
-	@IoExecutor
 	private void onSettingsUpdated(Settings settings) {
-		boolean enabledByUser = settings.getBoolean(PREF_PLUGIN_ENABLE, false);
+		boolean wasAllowed = shouldAllowContactConnections();
-		SS ss = state.setEnabledByUser(enabledByUser);
+		loadSettings(settings);
-		State s = getState();
+		boolean isAllowed = shouldAllowContactConnections();
-		if (ss != null) {
+		if (wasAllowed && !isAllowed) {
-			LOG.info("Disabled by user, closing server socket");
+			LOG.info("Contact connections disabled");
-			tryToClose(ss);
+			tryToClose(socket);
+			callback.transportDisabled();
 			disableAdapterIfEnabledByUs();
-		} else if (s == INACTIVE) {
+		} else if (!wasAllowed && isAllowed) {
-			LOG.info("Enabled by user, opening server socket");
+			LOG.info("Contact connections enabled");
 			if (isAdapterEnabled()) bind();
 			else enableAdapter();
 		}
@@ -480,70 +478,4 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 			tryToClose(ss);
 		}
 	}
-
-	@ThreadSafe
-	@NotNullByDefault
-	protected class PluginState {
-
-		@GuardedBy("this")
-		private boolean started = false,
-				stopped = false,
-				enabledByUser = false;
-
-		@GuardedBy("this")
-		@Nullable
-		private SS serverSocket = null;
-
-		synchronized void setStarted(boolean enabledByUser) {
-			started = true;
-			this.enabledByUser = enabledByUser;
-			callback.pluginStateChanged(getState());
-		}
-
-		@Nullable
-		synchronized SS setStopped() {
-			stopped = true;
-			SS ss = serverSocket;
-			serverSocket = null;
-			callback.pluginStateChanged(getState());
-			return ss;
-		}
-
-		@Nullable
-		synchronized SS setEnabledByUser(boolean enabledByUser) {
-			this.enabledByUser = enabledByUser;
-			SS ss = null;
-			if (!enabledByUser) {
-				ss = serverSocket;
-				serverSocket = null;
-			}
-			callback.pluginStateChanged(getState());
-			return ss;
-		}
-
-		synchronized boolean setServerSocket(SS ss) {
-			if (stopped || serverSocket != null) return false;
-			serverSocket = ss;
-			callback.pluginStateChanged(getState());
-			return true;
-		}
-
-		@Nullable
-		synchronized SS clearServerSocket() {
-			SS ss = serverSocket;
-			serverSocket = null;
-			callback.pluginStateChanged(getState());
-			return ss;
-		}
-
-		synchronized State getState() {
-			if (!started || stopped) return STARTING_STOPPING;
-			if (!enabledByUser) return DISABLED;
-			return serverSocket == null ? INACTIVE : ACTIVE;
-		}
-
-		synchronized int getReasonsDisabled() {
-			return getState() == DISABLED ? REASON_USER : 0;
-		}
-	}
 }

bramble-core/src/main/java/org/briarproject/bramble/plugin/file/FilePlugin.java

@@ -16,7 +16,6 @@ import java.util.logging.Logger;
 import static java.util.logging.Level.WARNING;
 import static java.util.logging.Logger.getLogger;
 import static org.briarproject.bramble.api.plugin.FileConstants.PROP_PATH;
-import static org.briarproject.bramble.api.plugin.Plugin.State.ACTIVE;
 import static org.briarproject.bramble.util.LogUtils.logException;
 import static org.briarproject.bramble.util.StringUtils.isNullOrEmpty;
 
@@ -46,7 +45,7 @@ abstract class FilePlugin implements SimplexPlugin {
 
 	@Override
 	public TransportConnectionReader createReader(TransportProperties p) {
-		if (getState() != ACTIVE) return null;
+		if (!isRunning()) return null;
 		String path = p.get(PROP_PATH);
 		if (isNullOrEmpty(path)) return null;
 		try {
@@ -61,7 +60,7 @@ abstract class FilePlugin implements SimplexPlugin {
 
 	@Override
 	public TransportConnectionWriter createWriter(TransportProperties p) {
-		if (getState() != ACTIVE) return null;
+		if (!isRunning()) return null;
 		String path = p.get(PROP_PATH);
 		if (isNullOrEmpty(path)) return null;
 		try {

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

@@ -11,6 +11,7 @@ import org.briarproject.bramble.api.plugin.TransportId;
 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.util.IoUtils;
 
 import java.io.IOException;
 import java.net.Inet4Address;
@@ -40,7 +41,6 @@ import static org.briarproject.bramble.api.plugin.LanTcpConstants.PREF_LAN_IP_PO
 import static org.briarproject.bramble.api.plugin.LanTcpConstants.PROP_IP_PORTS;
 import static org.briarproject.bramble.api.plugin.LanTcpConstants.PROP_PORT;
 import static org.briarproject.bramble.util.ByteUtils.MAX_16_BIT_UNSIGNED;
-import static org.briarproject.bramble.util.IoUtils.tryToClose;
 import static org.briarproject.bramble.util.PrivacyUtils.scrubSocketAddress;
 import static org.briarproject.bramble.util.StringUtils.isNullOrEmpty;
 import static org.briarproject.bramble.util.StringUtils.join;
@@ -91,8 +91,7 @@ class LanTcpPlugin extends TcpPlugin {
 	public void start() {
 		if (used.getAndSet(true)) throw new IllegalStateException();
 		initialisePortProperty();
-		Settings settings = callback.getSettings();
+		running = true;
-		state.setStarted(settings.getBoolean(PREF_PLUGIN_ENABLE, false));
 		bind();
 	}
 
@@ -272,10 +271,10 @@ class LanTcpPlugin extends TcpPlugin {
 			} catch (IOException e) {
 				if (LOG.isLoggable(INFO))
 					LOG.info("Failed to bind " + scrubSocketAddress(addr));
-				tryToClose(ss, LOG, WARNING);
+				tryToClose(ss);
 			}
 		}
-		if (ss == null) {
+		if (ss == null || !ss.isBound()) {
 			LOG.info("Could not bind server socket for key agreement");
 			return null;
 		}
@@ -291,8 +290,8 @@ class LanTcpPlugin extends TcpPlugin {
 	@Override
 	public DuplexTransportConnection createKeyAgreementConnection(
 			byte[] commitment, BdfList descriptor) {
-		ServerSocket ss = state.getServerSocket();
+		if (!isRunning()) return null;
-		if (ss == null) return null;
+		ServerSocket ss = socket;
 		InterfaceAddress local = getLocalInterfaceAddress(ss.getInetAddress());
 		if (local == null) {
 			LOG.warning("No interface for key agreement server socket");
@@ -364,7 +363,7 @@ class LanTcpPlugin extends TcpPlugin {
 
 		@Override
 		public void close() {
-			tryToClose(ss, LOG, WARNING);
+			IoUtils.tryToClose(ss, LOG, WARNING);
 		}
 	}
 }

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

@@ -1,6 +1,5 @@
 package org.briarproject.bramble.plugin.tcp;
 
-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;
@@ -27,13 +26,11 @@ public class LanTcpPluginFactory implements DuplexPluginFactory {
 	private static final double BACKOFF_BASE = 1.2;
 
 	private final Executor ioExecutor;
-	private final EventBus eventBus;
 	private final BackoffFactory backoffFactory;
 
-	public LanTcpPluginFactory(Executor ioExecutor, EventBus eventBus,
+	public LanTcpPluginFactory(Executor ioExecutor,
 			BackoffFactory backoffFactory) {
 		this.ioExecutor = ioExecutor;
-		this.eventBus = eventBus;
 		this.backoffFactory = backoffFactory;
 	}
 
@@ -51,9 +48,7 @@ public class LanTcpPluginFactory implements DuplexPluginFactory {
 	public DuplexPlugin createPlugin(PluginCallback callback) {
 		Backoff backoff = backoffFactory.createBackoff(MIN_POLLING_INTERVAL,
 				MAX_POLLING_INTERVAL, BACKOFF_BASE);
-		LanTcpPlugin plugin =  new LanTcpPlugin(ioExecutor, backoff, callback, MAX_LATENCY,
+		return new LanTcpPlugin(ioExecutor, backoff, callback, MAX_LATENCY,
 				MAX_IDLE_TIME, CONNECTION_TIMEOUT);
-		eventBus.addListener(plugin);
-		return plugin;
 	}
 }

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

@@ -2,23 +2,19 @@ package org.briarproject.bramble.plugin.tcp;
 
 import org.briarproject.bramble.PoliteExecutor;
 import org.briarproject.bramble.api.Pair;
-import org.briarproject.bramble.api.event.Event;
+import org.briarproject.bramble.api.data.BdfList;
-import org.briarproject.bramble.api.event.EventListener;
+import org.briarproject.bramble.api.keyagreement.KeyAgreementListener;
-import org.briarproject.bramble.api.lifecycle.IoExecutor;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.bramble.api.plugin.Backoff;
 import org.briarproject.bramble.api.plugin.ConnectionHandler;
-import org.briarproject.bramble.api.plugin.DiscoveryHandler;
 import org.briarproject.bramble.api.plugin.PluginCallback;
 import org.briarproject.bramble.api.plugin.duplex.DuplexPlugin;
 import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
 import org.briarproject.bramble.api.properties.TransportProperties;
 import org.briarproject.bramble.api.rendezvous.KeyMaterialSource;
 import org.briarproject.bramble.api.rendezvous.RendezvousEndpoint;
-import org.briarproject.bramble.api.settings.Settings;
+import org.briarproject.bramble.util.IoUtils;
-import org.briarproject.bramble.api.settings.event.SettingsUpdatedEvent;
 
 import java.io.IOException;
 import java.net.InetAddress;
@@ -39,26 +35,19 @@ import java.util.logging.Logger;
 import java.util.regex.Pattern;
 
 import javax.annotation.Nullable;
-import javax.annotation.concurrent.GuardedBy;
-import javax.annotation.concurrent.ThreadSafe;
 
 import static java.util.Collections.emptyList;
 import static java.util.Collections.list;
 import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
 import static java.util.logging.Logger.getLogger;
-import static org.briarproject.bramble.api.plugin.Plugin.State.ACTIVE;
-import static org.briarproject.bramble.api.plugin.Plugin.State.DISABLED;
-import static org.briarproject.bramble.api.plugin.Plugin.State.INACTIVE;
-import static org.briarproject.bramble.api.plugin.Plugin.State.STARTING_STOPPING;
-import static org.briarproject.bramble.util.IoUtils.tryToClose;
 import static org.briarproject.bramble.util.LogUtils.logException;
 import static org.briarproject.bramble.util.PrivacyUtils.scrubSocketAddress;
 import static org.briarproject.bramble.util.StringUtils.isNullOrEmpty;
 
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
-abstract class TcpPlugin implements DuplexPlugin, EventListener {
+abstract class TcpPlugin implements DuplexPlugin {
 
 	private static final Logger LOG = getLogger(TcpPlugin.class.getName());
 
@@ -71,7 +60,9 @@ abstract class TcpPlugin implements DuplexPlugin, EventListener {
 	protected final int maxLatency, maxIdleTime;
 	protected final int connectionTimeout, socketTimeout;
 	protected final AtomicBoolean used = new AtomicBoolean(false);
-	protected final PluginState state = new PluginState();
+
+	protected volatile boolean running = false;
+	protected volatile ServerSocket socket = null;
 
 	/**
 	 * Returns zero or more socket addresses on which the plugin should listen,
@@ -127,14 +118,14 @@ abstract class TcpPlugin implements DuplexPlugin, EventListener {
 	@Override
 	public void start() {
 		if (used.getAndSet(true)) throw new IllegalStateException();
-		Settings settings = callback.getSettings();
+		running = true;
-		state.setStarted(settings.getBoolean(PREF_PLUGIN_ENABLE, false));
 		bind();
 	}
 
 	protected void bind() {
 		bindExecutor.execute(() -> {
-			if (getState() != INACTIVE) return;
+			if (!running) return;
+			if (socket != null && !socket.isClosed()) return;
 			ServerSocket ss = null;
 			for (InetSocketAddress addr : getLocalSocketAddresses()) {
 				try {
@@ -144,28 +135,34 @@ abstract class TcpPlugin implements DuplexPlugin, EventListener {
 				} catch (IOException e) {
 					if (LOG.isLoggable(INFO))
 						LOG.info("Failed to bind " + scrubSocketAddress(addr));
-					tryToClose(ss, LOG, WARNING);
+					tryToClose(ss);
 				}
 			}
-			if (ss == null) {
+			if (ss == null || !ss.isBound()) {
 				LOG.info("Could not bind server socket");
 				return;
 			}
-			if (!state.setServerSocket(ss)) {
+			if (!running) {
-				LOG.info("Closing redundant server socket");
+				tryToClose(ss);
-				tryToClose(ss, LOG, WARNING);
 				return;
 			}
+			socket = ss;
 			backoff.reset();
 			InetSocketAddress local =
 					(InetSocketAddress) ss.getLocalSocketAddress();
 			setLocalSocketAddress(local);
 			if (LOG.isLoggable(INFO))
 				LOG.info("Listening on " + scrubSocketAddress(local));
-			acceptContactConnections(ss);
+			callback.transportEnabled();
+			acceptContactConnections();
 		});
 	}
 
+	protected void tryToClose(@Nullable ServerSocket ss) {
+		IoUtils.tryToClose(ss, LOG, WARNING);
+		callback.transportDisabled();
+	}
+
 	String getIpPortString(InetSocketAddress a) {
 		String addr = a.getAddress().getHostAddress();
 		int percent = addr.indexOf('%');
@@ -173,16 +170,15 @@ abstract class TcpPlugin implements DuplexPlugin, EventListener {
 		return addr + ":" + a.getPort();
 	}
 
-	private void acceptContactConnections(ServerSocket ss) {
+	private void acceptContactConnections() {
-		while (true) {
+		while (isRunning()) {
 			Socket s;
 			try {
-				s = ss.accept();
+				s = socket.accept();
 				s.setSoTimeout(socketTimeout);
 			} catch (IOException e) {
-				// This is expected when the server socket is closed
+				// This is expected when the socket is closed
-				LOG.info("Server socket closed");
+				if (LOG.isLoggable(INFO)) LOG.info(e.toString());
-				state.clearServerSocket(ss);
 				return;
 			}
 			if (LOG.isLoggable(INFO))
@@ -195,18 +191,13 @@ abstract class TcpPlugin implements DuplexPlugin, EventListener {
 
 	@Override
 	public void stop() {
-		ServerSocket ss = state.setStopped();
+		running = false;
-		tryToClose(ss, LOG, WARNING);
+		tryToClose(socket);
 	}
 
 	@Override
-	public State getState() {
+	public boolean isRunning() {
-		return state.getState();
+		return running && socket != null && !socket.isClosed();
-	}
-
-	@Override
-	public int getReasonsDisabled() {
-		return state.getReasonsDisabled();
 	}
 
 	@Override
@@ -220,9 +211,9 @@ abstract class TcpPlugin implements DuplexPlugin, EventListener {
 	}
 
 	@Override
-	public void poll(
+	public void poll(Collection<Pair<TransportProperties, ConnectionHandler>>
-			List<Pair<TransportProperties, ConnectionHandler>> properties) {
+			properties) {
-		if (getState() != ACTIVE) return;
+		if (!isRunning()) return;
 		backoff.increment();
 		for (Pair<TransportProperties, ConnectionHandler> p : properties) {
 			connect(p.getFirst(), p.getSecond());
@@ -241,8 +232,8 @@ abstract class TcpPlugin implements DuplexPlugin, EventListener {
 
 	@Override
 	public DuplexTransportConnection createConnection(TransportProperties p) {
-		ServerSocket ss = state.getServerSocket();
+		if (!isRunning()) return null;
-		if (ss == null) return null;
+		ServerSocket ss = socket;
 		InterfaceAddress local = getLocalInterfaceAddress(ss.getInetAddress());
 		if (local == null) {
 			LOG.warning("No interface for server socket");
@@ -322,6 +313,22 @@ abstract class TcpPlugin implements DuplexPlugin, EventListener {
 		}
 	}
 
+	@Override
+	public boolean supportsKeyAgreement() {
+		return false;
+	}
+
+	@Override
+	public KeyAgreementListener createKeyAgreementListener(byte[] commitment) {
+		throw new UnsupportedOperationException();
+	}
+
+	@Override
+	public DuplexTransportConnection createKeyAgreementConnection(
+			byte[] commitment, BdfList descriptor) {
+		throw new UnsupportedOperationException();
+	}
+
 	@Override
 	public boolean supportsRendezvous() {
 		return false;
@@ -333,17 +340,6 @@ abstract class TcpPlugin implements DuplexPlugin, EventListener {
 		throw new UnsupportedOperationException();
 	}
 
-	@Override
-	public boolean supportsDiscovery() {
-		return false;
-	}
-
-	@Override
-	public void discoverPeers(
-			List<Pair<TransportProperties, DiscoveryHandler>> properties) {
-		throw new UnsupportedOperationException();
-	}
-
 	List<InterfaceAddress> getLocalInterfaceAddresses() {
 		List<InterfaceAddress> addrs = new ArrayList<>();
 		for (NetworkInterface iface : getNetworkInterfaces()) {
@@ -370,93 +366,4 @@ abstract class TcpPlugin implements DuplexPlugin, EventListener {
 			return emptyList();
 		}
 	}
-
-	@Override
-	public void eventOccurred(Event e) {
-		if (e instanceof SettingsUpdatedEvent) {
-			SettingsUpdatedEvent s = (SettingsUpdatedEvent) e;
-			if (s.getNamespace().equals(getId().getString()))
-				ioExecutor.execute(() -> onSettingsUpdated(s.getSettings()));
-		}
-	}
-
-	@IoExecutor
-	private void onSettingsUpdated(Settings settings) {
-		boolean enabledByUser = settings.getBoolean(PREF_PLUGIN_ENABLE, false);
-		ServerSocket ss = state.setEnabledByUser(enabledByUser);
-		State s = getState();
-		if (ss != null) {
-			LOG.info("Disabled by user, closing server socket");
-			tryToClose(ss, LOG, WARNING);
-		} else if (s == INACTIVE) {
-			LOG.info("Enabled by user, opening server socket");
-			bind();
-		}
-	}
-
-	@ThreadSafe
-	@NotNullByDefault
-	protected class PluginState {
-
-		@GuardedBy("this")
-		private boolean started = false, stopped = false, enabledByUser = false;
-
-		@GuardedBy("this")
-		@Nullable
-		private ServerSocket serverSocket = null;
-
-		synchronized void setStarted(boolean enabledByUser) {
-			started = true;
-			this.enabledByUser = enabledByUser;
-			callback.pluginStateChanged(getState());
-		}
-
-		@Nullable
-		synchronized ServerSocket setStopped() {
-			stopped = true;
-			ServerSocket ss = serverSocket;
-			serverSocket = null;
-			callback.pluginStateChanged(getState());
-			return ss;
-		}
-
-		@Nullable
-		synchronized ServerSocket setEnabledByUser(boolean enabledByUser) {
-			this.enabledByUser = enabledByUser;
-			ServerSocket ss = null;
-			if (!enabledByUser) {
-				ss = serverSocket;
-				serverSocket = null;
-			}
-			callback.pluginStateChanged(getState());
-			return ss;
-		}
-
-		@Nullable
-		synchronized ServerSocket getServerSocket() {
-			return serverSocket;
-		}
-
-		synchronized boolean setServerSocket(ServerSocket ss) {
-			if (stopped || serverSocket != null) return false;
-			serverSocket = ss;
-			callback.pluginStateChanged(getState());
-			return true;
-		}
-
-		synchronized void clearServerSocket(ServerSocket ss) {
-			if (serverSocket == ss) serverSocket = null;
-			callback.pluginStateChanged(getState());
-		}
-
-		synchronized State getState() {
-			if (!started || stopped) return STARTING_STOPPING;
-			if (!enabledByUser) return DISABLED;
-			return serverSocket == null ? INACTIVE : ACTIVE;
-		}
-
-		synchronized int getReasonsDisabled() {
-			return getState() == DISABLED ? REASON_USER : 0;
-		}
-	}
 }

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

@@ -1,13 +1,10 @@
 package org.briarproject.bramble.plugin.tcp;
 
-import org.briarproject.bramble.api.data.BdfList;
-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.PluginCallback;
 import org.briarproject.bramble.api.plugin.TransportId;
-import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
 import org.briarproject.bramble.api.properties.TransportProperties;
 
 import java.net.Inet4Address;
@@ -45,22 +42,6 @@ class WanTcpPlugin extends TcpPlugin {
 		return ID;
 	}
 
-	@Override
-	public boolean supportsKeyAgreement() {
-		return false;
-	}
-
-	@Override
-	public KeyAgreementListener createKeyAgreementListener(byte[] commitment) {
-		throw new UnsupportedOperationException();
-	}
-
-	@Override
-	public DuplexTransportConnection createKeyAgreementConnection(
-			byte[] commitment, BdfList descriptor) {
-		throw new UnsupportedOperationException();
-	}
-
 	@Override
 	protected List<InetSocketAddress> getLocalSocketAddresses() {
 		// Use the same address and port as last time if available

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

@@ -1,6 +1,5 @@
 package org.briarproject.bramble.plugin.tcp;
 
-import org.briarproject.bramble.api.event.EventBus;
 import org.briarproject.bramble.api.lifecycle.ShutdownManager;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.Backoff;
@@ -28,14 +27,12 @@ public class WanTcpPluginFactory implements DuplexPluginFactory {
 	private static final double BACKOFF_BASE = 1.2;
 
 	private final Executor ioExecutor;
-	private final EventBus eventBus;
 	private final BackoffFactory backoffFactory;
 	private final ShutdownManager shutdownManager;
 
-	public WanTcpPluginFactory(Executor ioExecutor, EventBus eventBus,
+	public WanTcpPluginFactory(Executor ioExecutor,
 			BackoffFactory backoffFactory, ShutdownManager shutdownManager) {
 		this.ioExecutor = ioExecutor;
-		this.eventBus = eventBus;
 		this.backoffFactory = backoffFactory;
 		this.shutdownManager = shutdownManager;
 	}
@@ -54,10 +51,8 @@ public class WanTcpPluginFactory implements DuplexPluginFactory {
 	public DuplexPlugin createPlugin(PluginCallback callback) {
 		Backoff backoff = backoffFactory.createBackoff(MIN_POLLING_INTERVAL,
 				MAX_POLLING_INTERVAL, BACKOFF_BASE);
-		WanTcpPlugin plugin = new WanTcpPlugin(ioExecutor, backoff,
+		return new WanTcpPlugin(ioExecutor, backoff,
 				new PortMapperImpl(shutdownManager), callback, MAX_LATENCY,
 				MAX_IDLE_TIME, CONNECTION_TIMEOUT);
-		eventBus.addListener(plugin);
-		return plugin;
 	}
 }

bramble-core/src/main/java/org/briarproject/bramble/plugin/tor/CircumventionProvider.java

@@ -17,7 +17,7 @@ public interface CircumventionProvider {
 	String[] BLOCKED = {"CN", "IR", "EG", "BY", "TR", "SY", "VE"};
 
 	/**
-	 * Countries where obfs4 or meek bridge connections are likely to work.
+	 * Countries where obfs4 bridge connection are likely to work.
 	 * Should be a subset of {@link #BLOCKED}.
 	 */
 	String[] BRIDGES = { "CN", "IR", "EG", "BY", "TR", "SY", "VE" };

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

@@ -15,11 +15,9 @@ import org.briarproject.bramble.api.network.NetworkManager;
 import org.briarproject.bramble.api.network.NetworkStatus;
 import org.briarproject.bramble.api.network.event.NetworkStatusEvent;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.bramble.api.plugin.Backoff;
 import org.briarproject.bramble.api.plugin.ConnectionHandler;
-import org.briarproject.bramble.api.plugin.DiscoveryHandler;
 import org.briarproject.bramble.api.plugin.PluginCallback;
 import org.briarproject.bramble.api.plugin.PluginException;
 import org.briarproject.bramble.api.plugin.TorConstants;
@@ -56,9 +54,6 @@ import java.util.logging.Logger;
 import java.util.regex.Pattern;
 import java.util.zip.ZipInputStream;
 
-import javax.annotation.Nullable;
-import javax.annotation.concurrent.GuardedBy;
-import javax.annotation.concurrent.ThreadSafe;
 import javax.net.SocketFactory;
 
 import static java.util.Arrays.asList;
@@ -70,11 +65,6 @@ import static java.util.logging.Logger.getLogger;
 import static net.freehaven.tor.control.TorControlCommands.HS_ADDRESS;
 import static net.freehaven.tor.control.TorControlCommands.HS_PRIVKEY;
 import static org.briarproject.bramble.api.nullsafety.NullSafety.requireNonNull;
-import static org.briarproject.bramble.api.plugin.Plugin.State.ACTIVE;
-import static org.briarproject.bramble.api.plugin.Plugin.State.DISABLED;
-import static org.briarproject.bramble.api.plugin.Plugin.State.ENABLING;
-import static org.briarproject.bramble.api.plugin.Plugin.State.INACTIVE;
-import static org.briarproject.bramble.api.plugin.Plugin.State.STARTING_STOPPING;
 import static org.briarproject.bramble.api.plugin.TorConstants.CONTROL_PORT;
 import static org.briarproject.bramble.api.plugin.TorConstants.ID;
 import static org.briarproject.bramble.api.plugin.TorConstants.PREF_TOR_MOBILE;
@@ -86,9 +76,6 @@ import static org.briarproject.bramble.api.plugin.TorConstants.PREF_TOR_ONLY_WHE
 import static org.briarproject.bramble.api.plugin.TorConstants.PREF_TOR_PORT;
 import static org.briarproject.bramble.api.plugin.TorConstants.PROP_ONION_V2;
 import static org.briarproject.bramble.api.plugin.TorConstants.PROP_ONION_V3;
-import static org.briarproject.bramble.api.plugin.TorConstants.REASON_BATTERY;
-import static org.briarproject.bramble.api.plugin.TorConstants.REASON_COUNTRY_BLOCKED;
-import static org.briarproject.bramble.api.plugin.TorConstants.REASON_MOBILE_DATA;
 import static org.briarproject.bramble.plugin.tor.TorRendezvousCrypto.SEED_BYTES;
 import static org.briarproject.bramble.util.IoUtils.copyAndClose;
 import static org.briarproject.bramble.util.IoUtils.tryToClose;
@@ -126,14 +113,16 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 	private final int maxLatency, maxIdleTime, socketTimeout;
 	private final File torDirectory, torFile, geoIpFile, obfs4File, configFile;
 	private final File doneFile, cookieFile;
+	private final ConnectionStatus connectionStatus;
 	private final AtomicBoolean used = new AtomicBoolean(false);
 
-	protected final PluginState state = new PluginState();
+	private volatile ServerSocket socket = null;
-
 	private volatile Socket controlSocket = null;
 	private volatile TorControlConnection controlConnection = null;
 	private volatile Settings settings = null;
 
+	protected volatile boolean running = false;
+
 	protected abstract int getProcessId();
 
 	protected abstract long getLastUpdateTime();
@@ -170,6 +159,7 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 		configFile = new File(torDirectory, "torrc");
 		doneFile = new File(torDirectory, "done");
 		cookieFile = new File(torDirectory, ".tor/control_auth_cookie");
+		connectionStatus = new ConnectionStatus();
 		// Don't execute more than one connection status check at a time
 		connectionStatusExecutor =
 				new PoliteExecutor("TorPlugin", ioExecutor, 1);
@@ -200,7 +190,7 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 			}
 		}
 		// Load the settings
-		settings = migrateSettings(callback.getSettings());
+		settings = callback.getSettings();
 		// Install or update the assets if necessary
 		if (!assetsAreUpToDate()) installAssets();
 		if (cookieFile.exists() && !cookieFile.delete())
@@ -268,6 +258,7 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 			// Tell Tor to exit when the control connection is closed
 			controlConnection.takeOwnership();
 			controlConnection.resetConf(singletonList(OWNER));
+			running = true;
 			// Register to receive events from the Tor process
 			controlConnection.setEventHandler(this);
 			controlConnection.setEvents(asList(EVENTS));
@@ -275,12 +266,11 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 			String phase = controlConnection.getInfo("status/bootstrap-phase");
 			if (phase != null && phase.contains("PROGRESS=100")) {
 				LOG.info("Tor has already bootstrapped");
-				state.setBootstrapped();
+				connectionStatus.setBootstrapped();
 			}
 		} catch (IOException e) {
 			throw new PluginException(e);
 		}
-		state.setStarted();
 		// Check whether we're online
 		updateConnectionStatus(networkManager.getNetworkStatus(),
 				batteryManager.isCharging());
@@ -288,18 +278,6 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 		bind();
 	}
 
-	// TODO: Remove after a reasonable migration period (added 2020-01-16)
-	private Settings migrateSettings(Settings settings) {
-		int network = settings.getInt(PREF_TOR_NETWORK,
-				PREF_TOR_NETWORK_AUTOMATIC);
-		if (network == PREF_TOR_NETWORK_NEVER) {
-			settings.putInt(PREF_TOR_NETWORK, PREF_TOR_NETWORK_AUTOMATIC);
-			settings.putBoolean(PREF_PLUGIN_ENABLE, false);
-			callback.mergeSettings(settings);
-		}
-		return settings;
-	}
-
 	private boolean assetsAreUpToDate() {
 		return doneFile.lastModified() > getLastUpdateTime();
 	}
@@ -415,11 +393,11 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 				tryToClose(ss, LOG, WARNING);
 				return;
 			}
-			if (!state.setServerSocket(ss)) {
+			if (!running) {
-				LOG.info("Closing redundant server socket");
 				tryToClose(ss, LOG, WARNING);
 				return;
 			}
+			socket = ss;
 			// Store the port number
 			String localPort = String.valueOf(ss.getLocalPort());
 			Settings s = new Settings();
@@ -434,7 +412,7 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 	}
 
 	private void publishHiddenService(String port) {
-		if (!state.isTorRunning()) return;
+		if (!running) return;
 		LOG.info("Creating hidden service");
 		String privKey = settings.get(HS_PRIVKEY);
 		Map<Integer, String> portLines = singletonMap(80, "127.0.0.1:" + port);
@@ -472,15 +450,14 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 	}
 
 	private void acceptContactConnections(ServerSocket ss) {
-		while (true) {
+		while (running) {
 			Socket s;
 			try {
 				s = ss.accept();
 				s.setSoTimeout(socketTimeout);
 			} catch (IOException e) {
-				// This is expected when the server socket is closed
+				// This is expected when the socket is closed
-				LOG.info("Server socket closed");
+				if (LOG.isLoggable(INFO)) LOG.info(e.toString());
-				state.clearServerSocket(ss);
 				return;
 			}
 			LOG.info("Connection received");
@@ -490,8 +467,10 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 	}
 
 	protected void enableNetwork(boolean enable) throws IOException {
-		state.enableNetwork(enable);
+		if (!running) return;
+		connectionStatus.enableNetwork(enable);
 		controlConnection.setConf("DisableNetwork", enable ? "0" : "1");
+		if (!enable) callback.transportDisabled();
 	}
 
 	private void enableBridges(boolean enable, boolean needsMeek)
@@ -515,8 +494,9 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 
 	@Override
 	public void stop() {
-		ServerSocket ss = state.setStopped();
+		running = false;
-		tryToClose(ss, LOG, WARNING);
+		tryToClose(socket, LOG, WARNING);
+		callback.transportDisabled();
 		if (controlSocket != null && controlConnection != null) {
 			try {
 				LOG.info("Stopping Tor");
@@ -530,13 +510,8 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 	}
 
 	@Override
-	public State getState() {
+	public boolean isRunning() {
-		return state.getState();
+		return running && connectionStatus.isConnected();
-	}
-
-	@Override
-	public int getReasonsDisabled() {
-		return state.getReasonsDisabled();
 	}
 
 	@Override
@@ -550,9 +525,9 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 	}
 
 	@Override
-	public void poll(
+	public void poll(Collection<Pair<TransportProperties, ConnectionHandler>>
-			List<Pair<TransportProperties, ConnectionHandler>> properties) {
+			properties) {
-		if (getState() != ACTIVE) return;
+		if (!isRunning()) return;
 		backoff.increment();
 		for (Pair<TransportProperties, ConnectionHandler> p : properties) {
 			connect(p.getFirst(), p.getSecond());
@@ -571,7 +546,7 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 
 	@Override
 	public DuplexTransportConnection createConnection(TransportProperties p) {
-		if (getState() != ACTIVE) return null;
+		if (!isRunning()) return null;
 		String bestOnion = null;
 		String onion2 = p.get(PROP_ONION_V2);
 		String onion3 = p.get(PROP_ONION_V3);
@@ -659,8 +634,8 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 								new TorTransportConnection(this, s));
 					}
 				} catch (IOException e) {
-					// This is expected when the server socket is closed
+					// This is expected when the socket is closed
-					LOG.info("Rendezvous server socket closed");
+					if (LOG.isLoggable(INFO)) LOG.info(e.toString());
 				}
 			});
 			Map<Integer, String> portLines =
@@ -685,23 +660,13 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 		}
 	}
 
-	@Override
-	public boolean supportsDiscovery() {
-		return false;
-	}
-
-	@Override
-	public void discoverPeers(
-			List<Pair<TransportProperties, DiscoveryHandler>> properties) {
-		throw new UnsupportedOperationException();
-	}
-
 	@Override
 	public void circuitStatus(String status, String id, String path) {
 		if (status.equals("BUILT") &&
-				state.getAndSetCircuitBuilt()) {
+				connectionStatus.getAndSetCircuitBuilt()) {
 			LOG.info("First circuit built");
 			backoff.reset();
+			if (isRunning()) callback.transportEnabled();
 		}
 	}
 
@@ -732,8 +697,9 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 	public void message(String severity, String msg) {
 		if (LOG.isLoggable(INFO)) LOG.info(severity + " " + msg);
 		if (severity.equals("NOTICE") && msg.startsWith("Bootstrapped 100%")) {
-			state.setBootstrapped();
+			connectionStatus.setBootstrapped();
 			backoff.reset();
+			if (isRunning()) callback.transportEnabled();
 		}
 	}
 
@@ -770,7 +736,7 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 	private void disableNetwork() {
 		connectionStatusExecutor.execute(() -> {
 			try {
-				if (state.isTorRunning()) enableNetwork(false);
+				enableNetwork(false);
 			} catch (IOException ex) {
 				logException(LOG, WARNING, ex);
 			}
@@ -780,14 +746,12 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 	private void updateConnectionStatus(NetworkStatus status,
 			boolean charging) {
 		connectionStatusExecutor.execute(() -> {
-			if (!state.isTorRunning()) return;
+			if (!running) return;
 			boolean online = status.isConnected();
 			boolean wifi = status.isWifi();
 			String country = locationUtils.getCurrentCountry();
 			boolean blocked =
 					circumventionProvider.isTorProbablyBlocked(country);
-			boolean enabledByUser =
-					settings.getBoolean(PREF_PLUGIN_ENABLE, true);
 			int network = settings.getInt(PREF_TOR_NETWORK,
 					PREF_TOR_NETWORK_AUTOMATIC);
 			boolean useMobile = settings.getBoolean(PREF_TOR_MOBILE, true);
@@ -798,70 +762,47 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 
 			if (LOG.isLoggable(INFO)) {
 				LOG.info("Online: " + online + ", wifi: " + wifi);
-				if (country.isEmpty()) LOG.info("Country code unknown");
+				if ("".equals(country)) LOG.info("Country code unknown");
 				else LOG.info("Country code: " + country);
 				LOG.info("Charging: " + charging);
 			}
 
-			int reasonsDisabled = 0;
-			boolean enableNetwork = false, enableBridges = false;
-			boolean useMeek = false, enableConnectionPadding = false;
-
-			if (!online) {
-				LOG.info("Disabling network, device is offline");
-			} else {
-				if (!enabledByUser) {
-					LOG.info("User has disabled Tor");
-					reasonsDisabled |= REASON_USER;
-				}
-				if (!charging && onlyWhenCharging) {
-					LOG.info("Configured not to use battery");
-					reasonsDisabled |= REASON_BATTERY;
-				}
-				if (!useMobile && !wifi) {
-					LOG.info("Configured not to use mobile data");
-					reasonsDisabled |= REASON_MOBILE_DATA;
-				}
-				if (automatic && blocked && !bridgesWork) {
-					LOG.info("Country is blocked");
-					reasonsDisabled |= REASON_COUNTRY_BLOCKED;
-				}
-
-				if (reasonsDisabled != 0) {
-					LOG.info("Disabling network due to settings");
-				} else {
-					LOG.info("Enabling network");
-					enableNetwork = true;
-					if (network == PREF_TOR_NETWORK_WITH_BRIDGES ||
-							(automatic && bridgesWork)) {
-						if (circumventionProvider.needsMeek(country)) {
-							LOG.info("Using meek bridges");
-							enableBridges = true;
-							useMeek = true;
-						} else {
-							LOG.info("Using obfs4 bridges");
-							enableBridges = true;
-						}
-					} else {
-						LOG.info("Not using bridges");
-					}
-					if (wifi && charging) {
-						LOG.info("Enabling connection padding");
-						enableConnectionPadding = true;
-					} else {
-						LOG.info("Disabling connection padding");
-					}
-				}
-			}
-
-			state.setReasonsDisabled(reasonsDisabled);
-
 			try {
-				if (enableNetwork) {
+				if (!online) {
-					enableBridges(enableBridges, useMeek);
+					LOG.info("Disabling network, device is offline");
-					enableConnectionPadding(enableConnectionPadding);
+					enableNetwork(false);
+				} else if (!charging && onlyWhenCharging) {
+					LOG.info("Disabling network, device is on battery");
+					enableNetwork(false);
+				} else if (network == PREF_TOR_NETWORK_NEVER ||
+						(!useMobile && !wifi)) {
+					LOG.info("Disabling network, device is using mobile data");
+					enableNetwork(false);
+				} else if (automatic && blocked && !bridgesWork) {
+					LOG.info("Disabling network, country is blocked");
+					enableNetwork(false);
+				} else if (network == PREF_TOR_NETWORK_WITH_BRIDGES ||
+						(automatic && bridgesWork)) {
+					if (circumventionProvider.needsMeek(country)) {
+						LOG.info("Enabling network, using meek bridges");
+						enableBridges(true, true);
+					} else {
+						LOG.info("Enabling network, using obfs4 bridges");
+						enableBridges(true, false);
+					}
+					enableNetwork(true);
+				} else {
+					LOG.info("Enabling network, not using bridges");
+					enableBridges(false, false);
+					enableNetwork(true);
+				}
+				if (online && wifi && charging) {
+					LOG.info("Enabling connection padding");
+					enableConnectionPadding(true);
+				} else {
+					LOG.info("Disabling connection padding");
+					enableConnectionPadding(false);
 				}
-				enableNetwork(enableNetwork);
 			} catch (IOException e) {
 				logException(LOG, WARNING, e);
 			}
@@ -869,96 +810,33 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 	}
 
 	private void enableConnectionPadding(boolean enable) throws IOException {
+		if (!running) return;
 		controlConnection.setConf("ConnectionPadding", enable ? "1" : "0");
 	}
 
-	@ThreadSafe
+	private static class ConnectionStatus {
-	@NotNullByDefault
-	protected class PluginState {
 
-		@GuardedBy("this")
+		// All of the following are locking: this
-		private boolean started = false,
+		private boolean networkEnabled = false;
-				stopped = false,
+		private boolean bootstrapped = false, circuitBuilt = false;
-				networkInitialised = false,
-				networkEnabled = false,
-				bootstrapped = false,
-				circuitBuilt = false,
-				settingsChecked = false;
 
-		@GuardedBy("this")
+		private synchronized void setBootstrapped() {
-		private int reasonsDisabled = 0;
-
-		@GuardedBy("this")
-		@Nullable
-		private ServerSocket serverSocket = null;
-
-		synchronized void setStarted() {
-			started = true;
-			callback.pluginStateChanged(getState());
-		}
-
-		synchronized boolean isTorRunning() {
-			return started && !stopped;
-		}
-
-		@Nullable
-		synchronized ServerSocket setStopped() {
-			stopped = true;
-			ServerSocket ss = serverSocket;
-			serverSocket = null;
-			callback.pluginStateChanged(getState());
-			return ss;
-		}
-
-		synchronized void setBootstrapped() {
 			bootstrapped = true;
-			callback.pluginStateChanged(getState());
 		}
 
-		synchronized boolean getAndSetCircuitBuilt() {
+		private synchronized boolean getAndSetCircuitBuilt() {
 			boolean firstCircuit = !circuitBuilt;
 			circuitBuilt = true;
-			callback.pluginStateChanged(getState());
 			return firstCircuit;
 		}
 
-		synchronized void enableNetwork(boolean enable) {
+		private synchronized void enableNetwork(boolean enable) {
-			networkInitialised = true;
 			networkEnabled = enable;
 			if (!enable) circuitBuilt = false;
-			callback.pluginStateChanged(getState());
 		}
 
-		synchronized void setReasonsDisabled(int reasonsDisabled) {
+		private synchronized boolean isConnected() {
-			settingsChecked = true;
+			return networkEnabled && bootstrapped && circuitBuilt;
-			this.reasonsDisabled = reasonsDisabled;
-			callback.pluginStateChanged(getState());
-		}
-
-		// Doesn't affect getState()
-		synchronized boolean setServerSocket(ServerSocket ss) {
-			if (stopped || serverSocket != null) return false;
-			serverSocket = ss;
-			return true;
-		}
-
-		// Doesn't affect getState()
-		synchronized void clearServerSocket(ServerSocket ss) {
-			if (serverSocket == ss) serverSocket = null;
-		}
-
-		synchronized State getState() {
-			if (!started || stopped || !settingsChecked) {
-				return STARTING_STOPPING;
-			}
-			if (reasonsDisabled != 0) return DISABLED;
-			if (!networkInitialised) return ENABLING;
-			if (!networkEnabled) return INACTIVE;
-			return bootstrapped && circuitBuilt ? ACTIVE : ENABLING;
-		}
-
-		synchronized int getReasonsDisabled() {
-			return getState() == DISABLED ? reasonsDisabled : 0;
 		}
 	}
 }

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

@@ -37,6 +37,11 @@ import javax.annotation.Nullable;
 import javax.annotation.concurrent.Immutable;
 import javax.inject.Inject;
 
+import static org.briarproject.bramble.api.properties.TransportPropertyConstants.GROUP_KEY_DISCOVERED;
+import static org.briarproject.bramble.api.properties.TransportPropertyConstants.MSG_KEY_LOCAL;
+import static org.briarproject.bramble.api.properties.TransportPropertyConstants.MSG_KEY_TRANSPORT_ID;
+import static org.briarproject.bramble.api.properties.TransportPropertyConstants.MSG_KEY_VERSION;
+
 @Immutable
 @NotNullByDefault
 class TransportPropertyManagerImpl implements TransportPropertyManager,
@@ -111,10 +116,10 @@ class TransportPropertyManagerImpl implements TransportPropertyManager,
 		try {
 			// Find the latest update for this transport, if any
 			BdfDictionary d = metadataParser.parse(meta);
-			TransportId t = new TransportId(d.getString("transportId"));
+			TransportId t = new TransportId(d.getString(MSG_KEY_TRANSPORT_ID));
 			LatestUpdate latest = findLatest(txn, m.getGroupId(), t, false);
 			if (latest != null) {
-				if (d.getLong("version") > latest.version) {
+				if (d.getLong(MSG_KEY_VERSION) > latest.version) {
 					// This update is newer - delete the previous update
 					db.deleteMessage(txn, latest.messageId);
 					db.deleteMessageMetadata(txn, latest.messageId);
@@ -140,6 +145,27 @@ class TransportPropertyManagerImpl implements TransportPropertyManager,
 		}
 	}
 
+	@Override
+	public void addRemotePropertiesFromConnection(ContactId c, TransportId t,
+			TransportProperties props) throws DbException {
+		if (props.isEmpty()) return;
+		try {
+			db.transaction(false, txn -> {
+				Group g = getContactGroup(db.getContact(txn, c));
+				BdfDictionary meta = clientHelper.getGroupMetadataAsDictionary(
+						txn, g.getId());
+				BdfDictionary discovered =
+						meta.getOptionalDictionary(GROUP_KEY_DISCOVERED);
+				if (discovered == null) discovered = new BdfDictionary();
+				discovered.putAll(props);
+				meta.put(GROUP_KEY_DISCOVERED, discovered);
+				clientHelper.mergeGroupMetadata(txn, g.getId(), meta);
+			});
+		} catch (FormatException e) {
+			throw new DbException(e);
+		}
+	}
+
 	@Override
 	public Map<TransportId, TransportProperties> getLocalProperties()
 			throws DbException {
@@ -203,12 +229,26 @@ class TransportPropertyManagerImpl implements TransportPropertyManager,
 		Group g = getContactGroup(c);
 		try {
 			// Find the latest remote update
+			TransportProperties remote;
 			LatestUpdate latest = findLatest(txn, g.getId(), t, false);
-			if (latest == null) return new TransportProperties();
+			if (latest == null) {
-			// Retrieve and parse the latest remote properties
+				remote = new TransportProperties();
-			BdfList message =
+			} else {
-					clientHelper.getMessageAsList(txn, latest.messageId);
+				// Retrieve and parse the latest remote properties
-			return parseProperties(message);
+				BdfList message =
+						clientHelper.getMessageAsList(txn, latest.messageId);
+				remote = parseProperties(message);
+			}
+			// Merge in any discovered properties
+			BdfDictionary meta =
+					clientHelper.getGroupMetadataAsDictionary(txn, g.getId());
+			BdfDictionary d = meta.getOptionalDictionary(GROUP_KEY_DISCOVERED);
+			if (d == null) return remote;
+			TransportProperties merged =
+					clientHelper.parseAndValidateTransportProperties(d);
+			// Received properties override discovered properties
+			merged.putAll(remote);
+			return merged;
 		} catch (FormatException e) {
 			throw new DbException(e);
 		}
@@ -281,9 +321,9 @@ class TransportPropertyManagerImpl implements TransportPropertyManager,
 			long now = clock.currentTimeMillis();
 			Message m = clientHelper.createMessage(g, now, body);
 			BdfDictionary meta = new BdfDictionary();
-			meta.put("transportId", t.getString());
+			meta.put(MSG_KEY_TRANSPORT_ID, t.getString());
-			meta.put("version", version);
+			meta.put(MSG_KEY_VERSION, version);
-			meta.put("local", local);
+			meta.put(MSG_KEY_LOCAL, local);
 			clientHelper.addLocalMessage(txn, m, meta, shared, false);
 		} catch (FormatException e) {
 			throw new RuntimeException(e);
@@ -302,8 +342,9 @@ class TransportPropertyManagerImpl implements TransportPropertyManager,
 				.getMessageMetadataAsDictionary(txn, localGroup.getId());
 		for (Entry<MessageId, BdfDictionary> e : metadata.entrySet()) {
 			BdfDictionary meta = e.getValue();
-			TransportId t = new TransportId(meta.getString("transportId"));
+			TransportId t =
-			long version = meta.getLong("version");
+					new TransportId(meta.getString(MSG_KEY_TRANSPORT_ID));
+			long version = meta.getLong(MSG_KEY_VERSION);
 			latestUpdates.put(t, new LatestUpdate(e.getKey(), version));
 		}
 		return latestUpdates;
@@ -316,9 +357,10 @@ class TransportPropertyManagerImpl implements TransportPropertyManager,
 				clientHelper.getMessageMetadataAsDictionary(txn, g);
 		for (Entry<MessageId, BdfDictionary> e : metadata.entrySet()) {
 			BdfDictionary meta = e.getValue();
-			if (meta.getString("transportId").equals(t.getString())
+			if (meta.getString(MSG_KEY_TRANSPORT_ID).equals(t.getString())
-					&& meta.getBoolean("local") == local) {
+					&& meta.getBoolean(MSG_KEY_LOCAL) == local) {
-				return new LatestUpdate(e.getKey(), meta.getLong("version"));
+				return new LatestUpdate(e.getKey(),
+						meta.getLong(MSG_KEY_VERSION));
 			}
 		}
 		return null;

bramble-core/src/main/java/org/briarproject/bramble/rendezvous/RendezvousPollerImpl.java

@@ -31,8 +31,8 @@ import org.briarproject.bramble.api.plugin.TransportConnectionWriter;
 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.plugin.event.TransportActiveEvent;
+import org.briarproject.bramble.api.plugin.event.TransportDisabledEvent;
-import org.briarproject.bramble.api.plugin.event.TransportInactiveEvent;
+import org.briarproject.bramble.api.plugin.event.TransportEnabledEvent;
 import org.briarproject.bramble.api.properties.TransportProperties;
 import org.briarproject.bramble.api.rendezvous.KeyMaterialSource;
 import org.briarproject.bramble.api.rendezvous.RendezvousEndpoint;
@@ -269,11 +269,11 @@ class RendezvousPollerImpl implements RendezvousPoller, Service, EventListener {
 		} else if (e instanceof PendingContactRemovedEvent) {
 			PendingContactRemovedEvent p = (PendingContactRemovedEvent) e;
 			removePendingContactAsync(p.getId());
-		} else if (e instanceof TransportActiveEvent) {
+		} else if (e instanceof TransportEnabledEvent) {
-			TransportActiveEvent t = (TransportActiveEvent) e;
+			TransportEnabledEvent t = (TransportEnabledEvent) e;
 			addTransportAsync(t.getTransportId());
-		} else if (e instanceof TransportInactiveEvent) {
+		} else if (e instanceof TransportDisabledEvent) {
-			TransportInactiveEvent t = (TransportInactiveEvent) e;
+			TransportDisabledEvent t = (TransportDisabledEvent) e;
 			removeTransportAsync(t.getTransportId());
 		} else if (e instanceof RendezvousConnectionOpenedEvent) {
 			RendezvousConnectionOpenedEvent r =

bramble-core/src/main/java/org/briarproject/bramble/reporting/DevReporterImpl.java

@@ -6,7 +6,7 @@ import org.briarproject.bramble.api.event.EventListener;
 import org.briarproject.bramble.api.lifecycle.IoExecutor;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.TorConstants;
-import org.briarproject.bramble.api.plugin.event.TransportActiveEvent;
+import org.briarproject.bramble.api.plugin.event.TransportEnabledEvent;
 import org.briarproject.bramble.api.reporting.DevConfig;
 import org.briarproject.bramble.api.reporting.DevReporter;
 import org.briarproject.bramble.util.IoUtils;
@@ -92,8 +92,8 @@ class DevReporterImpl implements DevReporter, EventListener {
 
 	@Override
 	public void eventOccurred(Event e) {
-		if (e instanceof TransportActiveEvent) {
+		if (e instanceof TransportEnabledEvent) {
-			TransportActiveEvent t = (TransportActiveEvent) e;
+			TransportEnabledEvent t = (TransportEnabledEvent) e;
 			if (t.getTransportId().equals(TorConstants.ID))
 				ioExecutor.execute(this::sendReports);
 		}

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

@@ -11,6 +11,7 @@ import org.briarproject.bramble.api.event.EventListener;
 import org.briarproject.bramble.api.lifecycle.IoExecutor;
 import org.briarproject.bramble.api.lifecycle.event.LifecycleEvent;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.plugin.TransportId;
 import org.briarproject.bramble.api.sync.Ack;
 import org.briarproject.bramble.api.sync.Message;
 import org.briarproject.bramble.api.sync.Offer;
@@ -18,6 +19,7 @@ import org.briarproject.bramble.api.sync.Request;
 import org.briarproject.bramble.api.sync.SyncRecordWriter;
 import org.briarproject.bramble.api.sync.SyncSession;
 import org.briarproject.bramble.api.sync.Versions;
+import org.briarproject.bramble.api.sync.event.CloseSyncConnectionsEvent;
 import org.briarproject.bramble.api.sync.event.GroupVisibilityUpdatedEvent;
 import org.briarproject.bramble.api.sync.event.MessageRequestedEvent;
 import org.briarproject.bramble.api.sync.event.MessageSharedEvent;
@@ -71,6 +73,7 @@ class DuplexOutgoingSession implements SyncSession, EventListener {
 	private final EventBus eventBus;
 	private final Clock clock;
 	private final ContactId contactId;
+	private final TransportId transportId;
 	private final int maxLatency, maxIdleTime;
 	private final StreamWriter streamWriter;
 	private final SyncRecordWriter recordWriter;
@@ -86,14 +89,15 @@ class DuplexOutgoingSession implements SyncSession, EventListener {
 	private volatile boolean interrupted = false;
 
 	DuplexOutgoingSession(DatabaseComponent db, Executor dbExecutor,
-			EventBus eventBus, Clock clock, ContactId contactId, int maxLatency,
+			EventBus eventBus, Clock clock, ContactId contactId,
-			int maxIdleTime, StreamWriter streamWriter,
+			TransportId transportId, int maxLatency, int maxIdleTime,
-			SyncRecordWriter recordWriter) {
+			StreamWriter streamWriter, SyncRecordWriter recordWriter) {
 		this.db = db;
 		this.dbExecutor = dbExecutor;
 		this.eventBus = eventBus;
 		this.clock = clock;
 		this.contactId = contactId;
+		this.transportId = transportId;
 		this.maxLatency = maxLatency;
 		this.maxIdleTime = maxIdleTime;
 		this.streamWriter = streamWriter;
@@ -223,6 +227,9 @@ class DuplexOutgoingSession implements SyncSession, EventListener {
 		} else if (e instanceof LifecycleEvent) {
 			LifecycleEvent l = (LifecycleEvent) e;
 			if (l.getLifecycleState() == STOPPING) interrupt();
+		} else if (e instanceof CloseSyncConnectionsEvent) {
+			CloseSyncConnectionsEvent c = (CloseSyncConnectionsEvent) e;
+			if (c.getTransportId().equals(transportId)) interrupt();
 		}
 	}
 

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

@@ -11,11 +11,13 @@ import org.briarproject.bramble.api.event.EventListener;
 import org.briarproject.bramble.api.lifecycle.IoExecutor;
 import org.briarproject.bramble.api.lifecycle.event.LifecycleEvent;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.plugin.TransportId;
 import org.briarproject.bramble.api.sync.Ack;
 import org.briarproject.bramble.api.sync.Message;
 import org.briarproject.bramble.api.sync.SyncRecordWriter;
 import org.briarproject.bramble.api.sync.SyncSession;
 import org.briarproject.bramble.api.sync.Versions;
+import org.briarproject.bramble.api.sync.event.CloseSyncConnectionsEvent;
 import org.briarproject.bramble.api.transport.StreamWriter;
 
 import java.io.IOException;
@@ -56,6 +58,7 @@ class SimplexOutgoingSession implements SyncSession, EventListener {
 	private final Executor dbExecutor;
 	private final EventBus eventBus;
 	private final ContactId contactId;
+	private final TransportId transportId;
 	private final int maxLatency;
 	private final StreamWriter streamWriter;
 	private final SyncRecordWriter recordWriter;
@@ -65,12 +68,14 @@ class SimplexOutgoingSession implements SyncSession, EventListener {
 	private volatile boolean interrupted = false;
 
 	SimplexOutgoingSession(DatabaseComponent db, Executor dbExecutor,
-			EventBus eventBus, ContactId contactId, int maxLatency,
+			EventBus eventBus, ContactId contactId, TransportId transportId,
-			StreamWriter streamWriter, SyncRecordWriter recordWriter) {
+			int maxLatency, StreamWriter streamWriter,
+			SyncRecordWriter recordWriter) {
 		this.db = db;
 		this.dbExecutor = dbExecutor;
 		this.eventBus = eventBus;
 		this.contactId = contactId;
+		this.transportId = transportId;
 		this.maxLatency = maxLatency;
 		this.streamWriter = streamWriter;
 		this.recordWriter = recordWriter;
@@ -123,6 +128,9 @@ class SimplexOutgoingSession implements SyncSession, EventListener {
 		} else if (e instanceof LifecycleEvent) {
 			LifecycleEvent l = (LifecycleEvent) e;
 			if (l.getLifecycleState() == STOPPING) interrupt();
+		} else if (e instanceof CloseSyncConnectionsEvent) {
+			CloseSyncConnectionsEvent c = (CloseSyncConnectionsEvent) e;
+			if (c.getTransportId().equals(transportId)) interrupt();
 		}
 	}
 

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

@@ -5,6 +5,7 @@ import org.briarproject.bramble.api.db.DatabaseComponent;
 import org.briarproject.bramble.api.db.DatabaseExecutor;
 import org.briarproject.bramble.api.event.EventBus;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.plugin.TransportId;
 import org.briarproject.bramble.api.sync.SyncRecordReader;
 import org.briarproject.bramble.api.sync.SyncRecordReaderFactory;
 import org.briarproject.bramble.api.sync.SyncRecordWriter;
@@ -53,22 +54,23 @@ class SyncSessionFactoryImpl implements SyncSessionFactory {
 	}
 
 	@Override
-	public SyncSession createSimplexOutgoingSession(ContactId c,
+	public SyncSession createSimplexOutgoingSession(ContactId c, TransportId t,
 			int maxLatency, StreamWriter streamWriter) {
 		OutputStream out = streamWriter.getOutputStream();
 		SyncRecordWriter recordWriter =
 				recordWriterFactory.createRecordWriter(out);
-		return new SimplexOutgoingSession(db, dbExecutor, eventBus, c,
+		return new SimplexOutgoingSession(db, dbExecutor, eventBus, c, t,
 				maxLatency, streamWriter, recordWriter);
 	}
 
 	@Override
-	public SyncSession createDuplexOutgoingSession(ContactId c, int maxLatency,
+	public SyncSession createDuplexOutgoingSession(ContactId c,
-			int maxIdleTime, StreamWriter streamWriter) {
+			TransportId t, int maxLatency, int maxIdleTime,
+			StreamWriter streamWriter) {
 		OutputStream out = streamWriter.getOutputStream();
 		SyncRecordWriter recordWriter =
 				recordWriterFactory.createRecordWriter(out);
-		return new DuplexOutgoingSession(db, dbExecutor, eventBus, clock, c,
+		return new DuplexOutgoingSession(db, dbExecutor, eventBus, clock, c, t,
 				maxLatency, maxIdleTime, streamWriter, recordWriter);
 	}
 }

bramble-core/src/test/java/org/briarproject/bramble/account/AccountManagerImplTest.java

@@ -1,6 +1,7 @@
 package org.briarproject.bramble.account;
 
 import org.briarproject.bramble.api.crypto.CryptoComponent;
+import org.briarproject.bramble.api.crypto.DecryptionException;
 import org.briarproject.bramble.api.crypto.KeyStrengthener;
 import org.briarproject.bramble.api.crypto.SecretKey;
 import org.briarproject.bramble.api.db.DatabaseConfig;
@@ -19,12 +20,15 @@ import java.io.FileInputStream;
 import java.io.FileOutputStream;
 import java.io.IOException;
 import java.io.InputStreamReader;
+import java.nio.charset.Charset;
 
 import javax.annotation.Nullable;
 
 import static junit.framework.Assert.assertFalse;
 import static junit.framework.Assert.assertNull;
 import static junit.framework.Assert.assertTrue;
+import static org.briarproject.bramble.api.crypto.DecryptionResult.INVALID_CIPHERTEXT;
+import static org.briarproject.bramble.api.crypto.DecryptionResult.INVALID_PASSWORD;
 import static org.briarproject.bramble.test.TestUtils.deleteTestDirectory;
 import static org.briarproject.bramble.test.TestUtils.getIdentity;
 import static org.briarproject.bramble.test.TestUtils.getRandomBytes;
@@ -35,6 +39,7 @@ import static org.briarproject.bramble.util.StringUtils.toHexString;
 import static org.junit.Assert.assertArrayEquals;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.fail;
 
 public class AccountManagerImplTest extends BrambleMockTestCase {
 
@@ -83,8 +88,13 @@ public class AccountManagerImplTest extends BrambleMockTestCase {
 	}
 
 	@Test
-	public void testSignInReturnsFalseIfDbKeyCannotBeLoaded() {
+	public void testSignInThrowsExceptionIfDbKeyCannotBeLoaded() {
-		assertFalse(accountManager.signIn(password));
+		try {
+			accountManager.signIn(password);
+			fail();
+		} catch (DecryptionException expected) {
+			assertEquals(INVALID_CIPHERTEXT, expected.getDecryptionResult());
+		}
 		assertFalse(accountManager.hasDatabaseKey());
 
 		assertFalse(keyFile.exists());
@@ -92,11 +102,11 @@ public class AccountManagerImplTest extends BrambleMockTestCase {
 	}
 
 	@Test
-	public void testSignInReturnsFalseIfPasswordIsWrong() throws Exception {
+	public void testSignInThrowsExceptionIfPasswordIsWrong() throws Exception {
 		context.checking(new Expectations() {{
 			oneOf(crypto).decryptWithPassword(encryptedKey, password,
 					keyStrengthener);
-			will(returnValue(null));
+			will(throwException(new DecryptionException(INVALID_PASSWORD)));
 		}});
 
 		storeDatabaseKey(keyFile, encryptedKeyHex);
@@ -105,7 +115,12 @@ public class AccountManagerImplTest extends BrambleMockTestCase {
 		assertEquals(encryptedKeyHex, loadDatabaseKey(keyFile));
 		assertEquals(encryptedKeyHex, loadDatabaseKey(keyBackupFile));
 
-		assertFalse(accountManager.signIn(password));
+		try {
+			accountManager.signIn(password);
+			fail();
+		} catch (DecryptionException expected) {
+			assertEquals(INVALID_PASSWORD, expected.getDecryptionResult());
+		}
 		assertFalse(accountManager.hasDatabaseKey());
 
 		assertEquals(encryptedKeyHex, loadDatabaseKey(keyFile));
@@ -128,7 +143,7 @@ public class AccountManagerImplTest extends BrambleMockTestCase {
 		assertEquals(encryptedKeyHex, loadDatabaseKey(keyFile));
 		assertEquals(encryptedKeyHex, loadDatabaseKey(keyBackupFile));
 
-		assertTrue(accountManager.signIn(password));
+		accountManager.signIn(password);
 		assertTrue(accountManager.hasDatabaseKey());
 		SecretKey decrypted = accountManager.getDatabaseKey();
 		assertNotNull(decrypted);
@@ -157,7 +172,7 @@ public class AccountManagerImplTest extends BrambleMockTestCase {
 		assertEquals(encryptedKeyHex, loadDatabaseKey(keyFile));
 		assertEquals(encryptedKeyHex, loadDatabaseKey(keyBackupFile));
 
-		assertTrue(accountManager.signIn(password));
+		accountManager.signIn(password);
 		assertTrue(accountManager.hasDatabaseKey());
 		SecretKey decrypted = accountManager.getDatabaseKey();
 		assertNotNull(decrypted);
@@ -239,55 +254,6 @@ public class AccountManagerImplTest extends BrambleMockTestCase {
 		assertFalse(keyBackupFile.exists());
 	}
 
-	@Test
-	public void testAccountExistsReturnsFalseIfDbDirectoryDoesNotExist()
-			throws Exception {
-		storeDatabaseKey(keyFile, encryptedKeyHex);
-		storeDatabaseKey(keyBackupFile, encryptedKeyHex);
-
-		assertFalse(dbDir.exists());
-
-		assertFalse(accountManager.accountExists());
-
-		assertEquals(encryptedKeyHex, loadDatabaseKey(keyFile));
-		assertEquals(encryptedKeyHex, loadDatabaseKey(keyBackupFile));
-		assertFalse(dbDir.exists());
-	}
-
-	@Test
-	public void testAccountExistsReturnsFalseIfDbDirectoryIsNotDirectory()
-			throws Exception {
-		storeDatabaseKey(keyFile, encryptedKeyHex);
-		storeDatabaseKey(keyBackupFile, encryptedKeyHex);
-
-		assertTrue(dbDir.createNewFile());
-		assertFalse(dbDir.isDirectory());
-
-		assertFalse(accountManager.accountExists());
-
-		assertEquals(encryptedKeyHex, loadDatabaseKey(keyFile));
-		assertEquals(encryptedKeyHex, loadDatabaseKey(keyBackupFile));
-		assertTrue(dbDir.exists());
-		assertFalse(dbDir.isDirectory());
-	}
-
-	@Test
-	public void testAccountExistsReturnsTrueIfDbDirectoryIsDirectory()
-			throws Exception {
-		storeDatabaseKey(keyFile, encryptedKeyHex);
-		storeDatabaseKey(keyBackupFile, encryptedKeyHex);
-
-		assertTrue(dbDir.mkdirs());
-		assertTrue(dbDir.isDirectory());
-
-		assertTrue(accountManager.accountExists());
-
-		assertEquals(encryptedKeyHex, loadDatabaseKey(keyFile));
-		assertEquals(encryptedKeyHex, loadDatabaseKey(keyBackupFile));
-		assertTrue(dbDir.exists());
-		assertTrue(dbDir.isDirectory());
-	}
-
 	@Test
 	public void testCreateAccountStoresDbKey() throws Exception {
 		context.checking(new Expectations() {{
@@ -315,26 +281,36 @@ public class AccountManagerImplTest extends BrambleMockTestCase {
 	}
 
 	@Test
-	public void testChangePasswordReturnsFalseIfDbKeyCannotBeLoaded() {
+	public void testChangePasswordThrowsExceptionIfDbKeyCannotBeLoaded() {
-		assertFalse(accountManager.changePassword(password, newPassword));
+		try {
+			accountManager.changePassword(password, newPassword);
+			fail();
+		} catch (DecryptionException expected) {
+			assertEquals(INVALID_CIPHERTEXT, expected.getDecryptionResult());
+		}
 
 		assertFalse(keyFile.exists());
 		assertFalse(keyBackupFile.exists());
 	}
 
 	@Test
-	public void testChangePasswordReturnsFalseIfPasswordIsWrong()
+	public void testChangePasswordThrowsExceptionIfPasswordIsWrong()
 			throws Exception {
 		context.checking(new Expectations() {{
 			oneOf(crypto).decryptWithPassword(encryptedKey, password,
 					keyStrengthener);
-			will(returnValue(null));
+			will(throwException(new DecryptionException(INVALID_PASSWORD)));
 		}});
 
 		storeDatabaseKey(keyFile, encryptedKeyHex);
 		storeDatabaseKey(keyBackupFile, encryptedKeyHex);
 
-		assertFalse(accountManager.changePassword(password, newPassword));
+		try {
+			accountManager.changePassword(password, newPassword);
+			fail();
+		} catch (DecryptionException expected) {
+			assertEquals(INVALID_PASSWORD, expected.getDecryptionResult());
+		}
 
 		assertEquals(encryptedKeyHex, loadDatabaseKey(keyFile));
 		assertEquals(encryptedKeyHex, loadDatabaseKey(keyBackupFile));
@@ -357,7 +333,7 @@ public class AccountManagerImplTest extends BrambleMockTestCase {
 		storeDatabaseKey(keyFile, encryptedKeyHex);
 		storeDatabaseKey(keyBackupFile, encryptedKeyHex);
 
-		assertTrue(accountManager.changePassword(password, newPassword));
+		accountManager.changePassword(password, newPassword);
 
 		assertEquals(newEncryptedKeyHex, loadDatabaseKey(keyFile));
 		assertEquals(newEncryptedKeyHex, loadDatabaseKey(keyBackupFile));
@@ -366,7 +342,7 @@ public class AccountManagerImplTest extends BrambleMockTestCase {
 	private void storeDatabaseKey(File f, String hex) throws IOException {
 		f.getParentFile().mkdirs();
 		FileOutputStream out = new FileOutputStream(f);
-		out.write(hex.getBytes("UTF-8"));
+		out.write(hex.getBytes(Charset.forName("UTF-8")));
 		out.flush();
 		out.close();
 	}
@@ -374,7 +350,7 @@ public class AccountManagerImplTest extends BrambleMockTestCase {
 	@Nullable
 	private String loadDatabaseKey(File f) throws IOException {
 		BufferedReader reader = new BufferedReader(new InputStreamReader(
-				new FileInputStream(f), "UTF-8"));
+				new FileInputStream(f), Charset.forName("UTF-8")));
 		String hex = reader.readLine();
 		reader.close();
 		return hex;

bramble-core/src/test/java/org/briarproject/bramble/crypto/PasswordBasedEncryptionTest.java

@@ -1,25 +1,35 @@
 package org.briarproject.bramble.crypto;
 
+import org.briarproject.bramble.api.crypto.DecryptionException;
+import org.briarproject.bramble.api.crypto.KeyStrengthener;
+import org.briarproject.bramble.api.crypto.SecretKey;
 import org.briarproject.bramble.system.SystemClock;
-import org.briarproject.bramble.test.BrambleTestCase;
+import org.briarproject.bramble.test.BrambleMockTestCase;
 import org.briarproject.bramble.test.TestSecureRandomProvider;
-import org.briarproject.bramble.test.TestUtils;
+import org.jmock.Expectations;
 import org.junit.Test;
 
-import java.util.Random;
+import static org.briarproject.bramble.api.crypto.DecryptionResult.INVALID_CIPHERTEXT;
-
+import static org.briarproject.bramble.api.crypto.DecryptionResult.INVALID_PASSWORD;
+import static org.briarproject.bramble.api.crypto.DecryptionResult.KEY_STRENGTHENER_ERROR;
+import static org.briarproject.bramble.test.TestUtils.getRandomBytes;
+import static org.briarproject.bramble.test.TestUtils.getSecretKey;
 import static org.junit.Assert.assertArrayEquals;
-import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.fail;
 
-public class PasswordBasedEncryptionTest extends BrambleTestCase {
+public class PasswordBasedEncryptionTest extends BrambleMockTestCase {
+
+	private final KeyStrengthener keyStrengthener =
+			context.mock(KeyStrengthener.class);
 
 	private final CryptoComponentImpl crypto =
 			new CryptoComponentImpl(new TestSecureRandomProvider(),
 					new ScryptKdf(new SystemClock()));
 
 	@Test
-	public void testEncryptionAndDecryption() {
+	public void testEncryptionAndDecryption() throws Exception {
-		byte[] input = TestUtils.getRandomBytes(1234);
+		byte[] input = getRandomBytes(1234);
 		String password = "password";
 		byte[] ciphertext = crypto.encryptWithPassword(input, password, null);
 		byte[] output = crypto.decryptWithPassword(ciphertext, password, null);
@@ -27,14 +37,80 @@ public class PasswordBasedEncryptionTest extends BrambleTestCase {
 	}
 
 	@Test
-	public void testInvalidCiphertextReturnsNull() {
+	public void testInvalidFormatVersionThrowsException() {
-		byte[] input = TestUtils.getRandomBytes(1234);
+		byte[] input = getRandomBytes(1234);
 		String password = "password";
 		byte[] ciphertext = crypto.encryptWithPassword(input, password, null);
-		// Modify the ciphertext
+
-		int position = new Random().nextInt(ciphertext.length);
+		// Modify the format version
-		ciphertext[position] = (byte) (ciphertext[position] ^ 0xFF);
+		ciphertext[0] ^= (byte) 0xFF;
-		byte[] output = crypto.decryptWithPassword(ciphertext, password, null);
+		try {
-		assertNull(output);
+			crypto.decryptWithPassword(ciphertext, password, null);
+			fail();
+		} catch (DecryptionException expected) {
+			assertEquals(INVALID_CIPHERTEXT, expected.getDecryptionResult());
+		}
+	}
+
+	@Test
+	public void testInvalidPasswordThrowsException() {
+		byte[] input = getRandomBytes(1234);
+		byte[] ciphertext = crypto.encryptWithPassword(input, "password", null);
+
+		// Try to decrypt with the wrong password
+		try {
+			crypto.decryptWithPassword(ciphertext, "wrong", null);
+			fail();
+		} catch (DecryptionException expected) {
+			assertEquals(INVALID_PASSWORD, expected.getDecryptionResult());
+		}
+	}
+
+	@Test
+	public void testMissingKeyStrengthenerThrowsException() {
+		SecretKey strengthened = getSecretKey();
+		context.checking(new Expectations() {{
+			oneOf(keyStrengthener).strengthenKey(with(any(SecretKey.class)));
+			will(returnValue(strengthened));
+		}});
+
+		// Use the key strengthener during encryption
+		byte[] input = getRandomBytes(1234);
+		String password = "password";
+		byte[] ciphertext =
+				crypto.encryptWithPassword(input, password, keyStrengthener);
+
+		// The key strengthener is missing during decryption
+		try {
+			crypto.decryptWithPassword(ciphertext, password, null);
+			fail();
+		} catch (DecryptionException expected) {
+			assertEquals(KEY_STRENGTHENER_ERROR, expected.getDecryptionResult());
+		}
+	}
+
+	@Test
+	public void testKeyStrengthenerFailureThrowsException() {
+		SecretKey strengthened = getSecretKey();
+		context.checking(new Expectations() {{
+			oneOf(keyStrengthener).strengthenKey(with(any(SecretKey.class)));
+			will(returnValue(strengthened));
+			oneOf(keyStrengthener).isInitialised();
+			will(returnValue(false));
+		}});
+
+		// Use the key strengthener during encryption
+		byte[] input = getRandomBytes(1234);
+		String password = "password";
+		byte[] ciphertext =
+				crypto.encryptWithPassword(input, password, keyStrengthener);
+
+		// The key strengthener fails during decryption
+		try {
+			crypto.decryptWithPassword(ciphertext, password, keyStrengthener);
+			fail();
+		} catch (DecryptionException expected) {
+			assertEquals(KEY_STRENGTHENER_ERROR, expected.getDecryptionResult());
+		}
 	}
 }

bramble-core/src/test/java/org/briarproject/bramble/io/TimeoutInputStreamTest.java

@@ -0,0 +1,143 @@
+package org.briarproject.bramble.io;
+
+import org.briarproject.bramble.test.BrambleTestCase;
+import org.briarproject.bramble.test.SettableClock;
+import org.junit.Before;
+import org.junit.Test;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.concurrent.atomic.AtomicLong;
+
+import static java.util.concurrent.TimeUnit.MINUTES;
+import static java.util.concurrent.TimeUnit.SECONDS;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
+
+public class TimeoutInputStreamTest extends BrambleTestCase {
+
+	private static final long TIMEOUT_MS = MINUTES.toMillis(1);
+
+	private final long now = System.currentTimeMillis();
+
+	private AtomicLong time;
+	private UnresponsiveInputStream in;
+	private AtomicBoolean listenerCalled;
+	private TimeoutInputStream stream;
+	private CountDownLatch readReturned;
+
+	@Before
+	public void setUp() {
+		time = new AtomicLong(now);
+		in = new UnresponsiveInputStream();
+		listenerCalled = new AtomicBoolean(false);
+		stream = new TimeoutInputStream(new SettableClock(time), in,
+				TIMEOUT_MS, stream -> listenerCalled.set(true));
+		readReturned = new CountDownLatch(1);
+	}
+
+	@Test
+	public void testTimeoutIsReportedIfReadDoesNotReturn() throws Exception {
+		startReading();
+		try {
+			// The stream should not report a timeout
+			assertFalse(stream.hasTimedOut());
+
+			// Time passes
+			time.set(now + TIMEOUT_MS);
+
+			// The stream still shouldn't report a timeout
+			assertFalse(stream.hasTimedOut());
+
+			// Time passes
+			time.set(now + TIMEOUT_MS + 1);
+
+			// The stream should report a timeout
+			assertTrue(stream.hasTimedOut());
+
+			// The listener should not have been called yet
+			assertFalse(listenerCalled.get());
+
+			// Close the stream
+			stream.close();
+
+			// The listener should have been called
+			assertTrue(listenerCalled.get());
+		} finally {
+			// Allow the read to return
+			in.readFinished.countDown();
+		}
+	}
+
+	@Test
+	public void testTimeoutIsNotReportedIfReadReturns() throws Exception {
+		startReading();
+		try {
+			// The stream should not report a timeout
+			assertFalse(stream.hasTimedOut());
+
+			// Time passes
+			time.set(now + TIMEOUT_MS);
+
+			// The stream still shouldn't report a timeout
+			assertFalse(stream.hasTimedOut());
+
+			// Allow the read to finish and wait for it to return
+			in.readFinished.countDown();
+			readReturned.await(10, SECONDS);
+
+			// Time passes
+			time.set(now + TIMEOUT_MS + 1);
+
+			// The stream should not report a timeout as the read has returned
+			assertFalse(stream.hasTimedOut());
+
+			// The listener should not have been called yet
+			assertFalse(listenerCalled.get());
+
+			// Close the stream
+			stream.close();
+
+			// The listener should have been called
+			assertTrue(listenerCalled.get());
+		} finally {
+			// Allow the read to return in case an assertion was thrown
+			in.readFinished.countDown();
+		}
+	}
+
+	private void startReading() throws Exception {
+		// Start a background thread to read from the unresponsive stream
+		new Thread(() -> {
+			try {
+				assertEquals(123, stream.read());
+				readReturned.countDown();
+			} catch (IOException e) {
+				fail();
+			}
+		}).start();
+		// Wait for the background thread to start reading
+		assertTrue(in.readStarted.await(10, SECONDS));
+	}
+
+	private class UnresponsiveInputStream extends InputStream {
+
+		private final CountDownLatch readStarted = new CountDownLatch(1);
+		private final CountDownLatch readFinished = new CountDownLatch(1);
+
+		@Override
+		public int read() throws IOException {
+			readStarted.countDown();
+			try {
+				readFinished.await();
+				return 123;
+			} catch (InterruptedException e) {
+				throw new IOException(e);
+			}
+		}
+	}
+}

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

@@ -13,8 +13,8 @@ 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.TransportActiveEvent;
+import org.briarproject.bramble.api.plugin.event.TransportDisabledEvent;
-import org.briarproject.bramble.api.plugin.event.TransportInactiveEvent;
+import org.briarproject.bramble.api.plugin.event.TransportEnabledEvent;
 import org.briarproject.bramble.api.plugin.simplex.SimplexPlugin;
 import org.briarproject.bramble.api.properties.TransportProperties;
 import org.briarproject.bramble.api.properties.TransportPropertyManager;
@@ -38,7 +38,7 @@ import static java.util.Collections.emptyList;
 import static java.util.Collections.singletonList;
 import static java.util.Collections.singletonMap;
 import static java.util.concurrent.TimeUnit.MILLISECONDS;
-import static org.briarproject.bramble.test.ListMatcher.listOf;
+import static org.briarproject.bramble.test.CollectionMatcher.collectionOf;
 import static org.briarproject.bramble.test.PairMatcher.pairOf;
 import static org.briarproject.bramble.test.TestUtils.getContactId;
 import static org.briarproject.bramble.test.TestUtils.getTransportId;
@@ -322,7 +322,7 @@ public class PollerImplTest extends BrambleMockTestCase {
 	}
 
 	@Test
-	public void testPollsOnTransportActivated() throws Exception {
+	public void testPollsOnTransportEnabled() throws Exception {
 		DuplexPlugin plugin = context.mock(DuplexPlugin.class);
 
 		context.checking(new Expectations() {{
@@ -351,20 +351,17 @@ public class PollerImplTest extends BrambleMockTestCase {
 			oneOf(scheduler).schedule(with(any(Runnable.class)),
 					with((long) (pollingInterval * 0.5)), with(MILLISECONDS));
 			will(returnValue(future));
-			// FIXME: Revert
-			oneOf(plugin).supportsDiscovery();
-			will(returnValue(false));
 			// Get the transport properties and connected contacts
 			oneOf(transportPropertyManager).getRemoteProperties(transportId);
 			will(returnValue(singletonMap(contactId, properties)));
 			oneOf(connectionRegistry).getConnectedContacts(transportId);
 			will(returnValue(emptyList()));
 			// Poll the plugin
-			oneOf(plugin).poll(with(listOf(pairOf(
+			oneOf(plugin).poll(with(collectionOf(
-					equal(properties), any(ConnectionHandler.class)))));
+					pairOf(equal(properties), any(ConnectionHandler.class)))));
 		}});
 
-		poller.eventOccurred(new TransportActiveEvent(transportId));
+		poller.eventOccurred(new TransportEnabledEvent(transportId));
 	}
 
 	@Test
@@ -397,9 +394,6 @@ public class PollerImplTest extends BrambleMockTestCase {
 			oneOf(scheduler).schedule(with(any(Runnable.class)),
 					with((long) (pollingInterval * 0.5)), with(MILLISECONDS));
 			will(returnValue(future));
-			// FIXME: Revert
-			oneOf(plugin).supportsDiscovery();
-			will(returnValue(false));
 			// Get the transport properties and connected contacts
 			oneOf(transportPropertyManager).getRemoteProperties(transportId);
 			will(returnValue(singletonMap(contactId, properties)));
@@ -408,11 +402,11 @@ public class PollerImplTest extends BrambleMockTestCase {
 			// All contacts are connected, so don't poll the plugin
 		}});
 
-		poller.eventOccurred(new TransportActiveEvent(transportId));
+		poller.eventOccurred(new TransportEnabledEvent(transportId));
 	}
 
 	@Test
-	public void testCancelsPollingOnTransportDeactivated() {
+	public void testCancelsPollingOnTransportDisabled() {
 		Plugin plugin = context.mock(Plugin.class);
 
 		context.checking(new Expectations() {{
@@ -430,11 +424,11 @@ public class PollerImplTest extends BrambleMockTestCase {
 			oneOf(scheduler).schedule(with(any(Runnable.class)), with(0L),
 					with(MILLISECONDS));
 			will(returnValue(future));
-			// The plugin is deactivated before the task runs - cancel the task
+			// The plugin is disabled before the task runs - cancel the task
 			oneOf(future).cancel(false);
 		}});
 
-		poller.eventOccurred(new TransportActiveEvent(transportId));
+		poller.eventOccurred(new TransportEnabledEvent(transportId));
-		poller.eventOccurred(new TransportInactiveEvent(transportId));
+		poller.eventOccurred(new TransportDisabledEvent(transportId));
 	}
 }

bramble-core/src/test/java/org/briarproject/bramble/plugin/bluetooth/BluetoothConnectionLimiterImplTest.java

@@ -0,0 +1,182 @@
+package org.briarproject.bramble.plugin.bluetooth;
+
+import org.briarproject.bramble.api.event.EventBus;
+import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
+import org.briarproject.bramble.api.sync.event.CloseSyncConnectionsEvent;
+import org.briarproject.bramble.api.system.Clock;
+import org.briarproject.bramble.test.BrambleMockTestCase;
+import org.briarproject.bramble.test.SettableClock;
+import org.jmock.Expectations;
+import org.junit.Before;
+import org.junit.Test;
+
+import java.util.concurrent.atomic.AtomicLong;
+
+import static org.briarproject.bramble.plugin.bluetooth.BluetoothConnectionLimiter.MIN_ATTEMPT_INTERVAL_MS;
+import static org.briarproject.bramble.plugin.bluetooth.BluetoothConnectionLimiter.STABILITY_PERIOD_MS;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+public class BluetoothConnectionLimiterImplTest extends BrambleMockTestCase {
+
+	private final EventBus eventBus = context.mock(EventBus.class);
+
+	private final DuplexTransportConnection conn1 =
+			context.mock(DuplexTransportConnection.class, "conn1");
+	private final DuplexTransportConnection conn2 =
+			context.mock(DuplexTransportConnection.class, "conn2");
+	private final DuplexTransportConnection conn3 =
+			context.mock(DuplexTransportConnection.class, "conn3");
+
+	private final long now = System.currentTimeMillis();
+
+	private AtomicLong time;
+	private BluetoothConnectionLimiter limiter;
+
+	@Before
+	public void setUp() {
+		time = new AtomicLong(now);
+		Clock clock = new SettableClock(time);
+		limiter = new BluetoothConnectionLimiterImpl(eventBus, clock);
+	}
+
+	@Test
+	public void testLimiterDoesNotAllowContactConnectionsDuringKeyAgreement() {
+		assertTrue(limiter.canOpenContactConnection());
+
+		expectCloseSyncConnectionsEvent();
+		limiter.keyAgreementStarted();
+
+		assertFalse(limiter.canOpenContactConnection());
+
+		limiter.keyAgreementEnded();
+
+		assertTrue(limiter.canOpenContactConnection());
+	}
+
+	@Test
+	public void testLimiterAllowsAttemptToRaiseLimitAtStartup() {
+		// First outgoing connection is allowed - we're below the limit of 1
+		assertTrue(limiter.canOpenContactConnection());
+		assertTrue(limiter.contactConnectionOpened(conn1, false));
+
+		// Second outgoing connection is allowed - it's time to try raising
+		// the limit to 2
+		assertTrue(limiter.canOpenContactConnection());
+		assertTrue(limiter.contactConnectionOpened(conn2, false));
+
+		// Third outgoing connection is not allowed - we're above the limit of 1
+		assertFalse(limiter.canOpenContactConnection());
+	}
+
+	@Test
+	public void testLimiterAllowsThirdConnectionAfterFirstTwoAreClosed() {
+		// First outgoing connection is allowed - we're below the limit of 1
+		assertTrue(limiter.canOpenContactConnection());
+		assertTrue(limiter.contactConnectionOpened(conn1, false));
+
+		// Second outgoing connection is allowed - it's time to try raising
+		// the limit to 2
+		assertTrue(limiter.canOpenContactConnection());
+		assertTrue(limiter.contactConnectionOpened(conn2, false));
+
+		// Third outgoing connection is not allowed - we're above the limit of 1
+		assertFalse(limiter.canOpenContactConnection());
+
+		// Close the first connection
+		limiter.connectionClosed(conn1, false);
+
+		// Third outgoing connection is not allowed - we're at the limit of 1
+		assertFalse(limiter.canOpenContactConnection());
+
+		// Close the second connection
+		limiter.connectionClosed(conn2, false);
+
+		// Third outgoing connection is allowed - we're below the limit of 1
+		assertTrue(limiter.canOpenContactConnection());
+		assertTrue(limiter.contactConnectionOpened(conn3, false));
+	}
+
+	@Test
+	public void testLimiterRaisesLimitWhenConnectionsAreStable() {
+		// First outgoing connection is allowed - we're below the limit of 1
+		assertTrue(limiter.canOpenContactConnection());
+		assertTrue(limiter.contactConnectionOpened(conn1, false));
+
+		// Second outgoing connection is allowed - it's time to try raising
+		// the limit to 2
+		assertTrue(limiter.canOpenContactConnection());
+		assertTrue(limiter.contactConnectionOpened(conn2, false));
+
+		// Third outgoing connection is not allowed - we're above the limit of 1
+		assertFalse(limiter.canOpenContactConnection());
+
+		// Time passes
+		time.set(now + STABILITY_PERIOD_MS);
+
+		// Third outgoing connection is still not allowed - first two are now
+		// stable so limit is raised to 2, but we're already at the new limit
+		assertFalse(limiter.canOpenContactConnection());
+
+		// Time passes
+		time.set(now + MIN_ATTEMPT_INTERVAL_MS);
+
+		// Third outgoing connection is allowed - it's time to try raising
+		// the limit to 3
+		assertTrue(limiter.canOpenContactConnection());
+		assertTrue(limiter.contactConnectionOpened(conn3, false));
+
+		// Fourth outgoing connection is not allowed - we're above the limit
+		// of 2
+		assertFalse(limiter.canOpenContactConnection());
+	}
+
+	@Test
+	public void testLimiterIncreasesIntervalWhenConnectionFailsAboveLimit() {
+		// First outgoing connection is allowed - we're below the limit of 1
+		assertTrue(limiter.canOpenContactConnection());
+		assertTrue(limiter.contactConnectionOpened(conn1, false));
+
+		// Time passes
+		time.set(now + 1);
+
+		// Second outgoing connection is allowed - it's time to try raising
+		// the limit to 2
+		assertTrue(limiter.canOpenContactConnection());
+		assertTrue(limiter.contactConnectionOpened(conn2, false));
+
+		// Time passes - the first connection is stable, the second isn't
+		time.set(now + STABILITY_PERIOD_MS);
+
+		// First connection fails. The second connection isn't stable yet, so
+		// the limiter considers this a failed attempt and doubles the interval
+		// between attempts
+		limiter.connectionClosed(conn1, true);
+
+		// Third outgoing connection is not allowed - we're still at the limit
+		// of 1
+		assertFalse(limiter.canOpenContactConnection());
+
+		// Time passes - nearly time for the second attempt
+		time.set(now + MIN_ATTEMPT_INTERVAL_MS * 2);
+
+		// Third outgoing connection is not allowed - we're still at the limit
+		// of 1
+		assertFalse(limiter.canOpenContactConnection());
+
+		// Time passes - now it's time for the second attempt
+		time.set(now + 1 + MIN_ATTEMPT_INTERVAL_MS * 2);
+
+		// Third outgoing connection is allowed - it's time to try raising the
+		// limit to 2 again
+		assertTrue(limiter.canOpenContactConnection());
+		assertTrue(limiter.contactConnectionOpened(conn3, false));
+	}
+
+	private void expectCloseSyncConnectionsEvent() {
+		context.checking(new Expectations() {{
+			oneOf(eventBus).broadcast(with(any(
+					CloseSyncConnectionsEvent.class)));
+		}});
+	}
+}

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

@@ -4,7 +4,6 @@ import org.briarproject.bramble.api.data.BdfList;
 import org.briarproject.bramble.api.keyagreement.KeyAgreementListener;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.Backoff;
-import org.briarproject.bramble.api.plugin.Plugin.State;
 import org.briarproject.bramble.api.plugin.PluginCallback;
 import org.briarproject.bramble.api.plugin.TransportConnectionReader;
 import org.briarproject.bramble.api.plugin.TransportConnectionWriter;
@@ -32,7 +31,6 @@ import static java.util.concurrent.Executors.newCachedThreadPool;
 import static java.util.concurrent.TimeUnit.SECONDS;
 import static org.briarproject.bramble.api.keyagreement.KeyAgreementConstants.COMMIT_LENGTH;
 import static org.briarproject.bramble.api.keyagreement.KeyAgreementConstants.TRANSPORT_ID_LAN;
-import static org.briarproject.bramble.api.plugin.Plugin.PREF_PLUGIN_ENABLE;
 import static org.briarproject.bramble.plugin.tcp.LanTcpPlugin.areAddressesInSameNetwork;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
@@ -304,15 +302,10 @@ public class LanTcpPluginTest extends BrambleTestCase {
 		private final CountDownLatch propertiesLatch = new CountDownLatch(2);
 		private final CountDownLatch connectionsLatch = new CountDownLatch(1);
 		private final TransportProperties local = new TransportProperties();
-		private final Settings settings = new Settings();
-
-		private Callback() {
-			settings.putBoolean(PREF_PLUGIN_ENABLE, true);
-		}
 
 		@Override
 		public Settings getSettings() {
-			return settings;
+			return new Settings();
 		}
 
 		@Override
@@ -331,7 +324,11 @@ public class LanTcpPluginTest extends BrambleTestCase {
 		}
 
 		@Override
-		public void pluginStateChanged(State newState) {
+		public void transportEnabled() {
+		}
+
+		@Override
+		public void transportDisabled() {
 		}
 
 		@Override

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

@@ -24,14 +24,18 @@ import org.briarproject.bramble.test.DbExpectations;
 import org.jmock.Expectations;
 import org.junit.Test;
 
-import java.util.Collections;
 import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
 
 import static java.util.Arrays.asList;
+import static java.util.Collections.emptyMap;
 import static java.util.Collections.singletonList;
 import static java.util.Collections.singletonMap;
+import static org.briarproject.bramble.api.properties.TransportPropertyConstants.GROUP_KEY_DISCOVERED;
+import static org.briarproject.bramble.api.properties.TransportPropertyConstants.MSG_KEY_LOCAL;
+import static org.briarproject.bramble.api.properties.TransportPropertyConstants.MSG_KEY_TRANSPORT_ID;
+import static org.briarproject.bramble.api.properties.TransportPropertyConstants.MSG_KEY_VERSION;
 import static org.briarproject.bramble.api.properties.TransportPropertyManager.CLIENT_ID;
 import static org.briarproject.bramble.api.properties.TransportPropertyManager.MAJOR_VERSION;
 import static org.briarproject.bramble.api.sync.Group.Visibility.SHARED;
@@ -186,25 +190,25 @@ public class TransportPropertyManagerImplTest extends BrambleMockTestCase {
 		Message message = getMessage(contactGroupId);
 		Metadata meta = new Metadata();
 		BdfDictionary metaDictionary = BdfDictionary.of(
-				new BdfEntry("transportId", "foo"),
+				new BdfEntry(MSG_KEY_TRANSPORT_ID, "foo"),
-				new BdfEntry("version", 2),
+				new BdfEntry(MSG_KEY_VERSION, 2),
-				new BdfEntry("local", false)
+				new BdfEntry(MSG_KEY_LOCAL, false)
 		);
 		Map<MessageId, BdfDictionary> messageMetadata =
 				new LinkedHashMap<>();
 		// A remote update for another transport should be ignored
 		MessageId barUpdateId = new MessageId(getRandomId());
 		messageMetadata.put(barUpdateId, BdfDictionary.of(
-				new BdfEntry("transportId", "bar"),
+				new BdfEntry(MSG_KEY_TRANSPORT_ID, "bar"),
-				new BdfEntry("version", 1),
+				new BdfEntry(MSG_KEY_VERSION, 1),
-				new BdfEntry("local", false)
+				new BdfEntry(MSG_KEY_LOCAL, false)
 		));
 		// A local update for the same transport should be ignored
 		MessageId localUpdateId = new MessageId(getRandomId());
 		messageMetadata.put(localUpdateId, BdfDictionary.of(
-				new BdfEntry("transportId", "foo"),
+				new BdfEntry(MSG_KEY_TRANSPORT_ID, "foo"),
-				new BdfEntry("version", 1),
+				new BdfEntry(MSG_KEY_VERSION, 1),
-				new BdfEntry("local", true)
+				new BdfEntry(MSG_KEY_LOCAL, true)
 		));
 
 		context.checking(new Expectations() {{
@@ -228,18 +232,18 @@ public class TransportPropertyManagerImplTest extends BrambleMockTestCase {
 		Metadata meta = new Metadata();
 		// Version 4 is being delivered
 		BdfDictionary metaDictionary = BdfDictionary.of(
-				new BdfEntry("transportId", "foo"),
+				new BdfEntry(MSG_KEY_TRANSPORT_ID, "foo"),
-				new BdfEntry("version", 4),
+				new BdfEntry(MSG_KEY_VERSION, 4),
-				new BdfEntry("local", false)
+				new BdfEntry(MSG_KEY_LOCAL, false)
 		);
 		Map<MessageId, BdfDictionary> messageMetadata =
 				new LinkedHashMap<>();
 		// An older remote update for the same transport should be deleted
 		MessageId fooVersion3 = new MessageId(getRandomId());
 		messageMetadata.put(fooVersion3, BdfDictionary.of(
-				new BdfEntry("transportId", "foo"),
+				new BdfEntry(MSG_KEY_TRANSPORT_ID, "foo"),
-				new BdfEntry("version", 3),
+				new BdfEntry(MSG_KEY_VERSION, 3),
-				new BdfEntry("local", false)
+				new BdfEntry(MSG_KEY_LOCAL, false)
 		));
 
 		context.checking(new Expectations() {{
@@ -265,18 +269,18 @@ public class TransportPropertyManagerImplTest extends BrambleMockTestCase {
 		Metadata meta = new Metadata();
 		// Version 3 is being delivered
 		BdfDictionary metaDictionary = BdfDictionary.of(
-				new BdfEntry("transportId", "foo"),
+				new BdfEntry(MSG_KEY_TRANSPORT_ID, "foo"),
-				new BdfEntry("version", 3),
+				new BdfEntry(MSG_KEY_VERSION, 3),
-				new BdfEntry("local", false)
+				new BdfEntry(MSG_KEY_LOCAL, false)
 		);
 		Map<MessageId, BdfDictionary> messageMetadata =
 				new LinkedHashMap<>();
 		// A newer remote update for the same transport should not be deleted
 		MessageId fooVersion4 = new MessageId(getRandomId());
 		messageMetadata.put(fooVersion4, BdfDictionary.of(
-				new BdfEntry("transportId", "foo"),
+				new BdfEntry(MSG_KEY_TRANSPORT_ID, "foo"),
-				new BdfEntry("version", 4),
+				new BdfEntry(MSG_KEY_VERSION, 4),
-				new BdfEntry("local", false)
+				new BdfEntry(MSG_KEY_LOCAL, false)
 		));
 
 		context.checking(new Expectations() {{
@@ -342,9 +346,9 @@ public class TransportPropertyManagerImplTest extends BrambleMockTestCase {
 		// A local update for another transport should be ignored
 		MessageId barUpdateId = new MessageId(getRandomId());
 		messageMetadata.put(barUpdateId, BdfDictionary.of(
-				new BdfEntry("transportId", "bar"),
+				new BdfEntry(MSG_KEY_TRANSPORT_ID, "bar"),
-				new BdfEntry("version", 1),
+				new BdfEntry(MSG_KEY_VERSION, 1),
-				new BdfEntry("local", true)
+				new BdfEntry(MSG_KEY_LOCAL, true)
 		));
 
 		context.checking(new DbExpectations() {{
@@ -366,16 +370,16 @@ public class TransportPropertyManagerImplTest extends BrambleMockTestCase {
 		// A local update for another transport should be ignored
 		MessageId barUpdateId = new MessageId(getRandomId());
 		messageMetadata.put(barUpdateId, BdfDictionary.of(
-				new BdfEntry("transportId", "bar"),
+				new BdfEntry(MSG_KEY_TRANSPORT_ID, "bar"),
-				new BdfEntry("version", 1),
+				new BdfEntry(MSG_KEY_VERSION, 1),
-				new BdfEntry("local", true)
+				new BdfEntry(MSG_KEY_LOCAL, true)
 		));
 		// A local update for the right transport should be returned
 		MessageId fooUpdateId = new MessageId(getRandomId());
 		messageMetadata.put(fooUpdateId, BdfDictionary.of(
-				new BdfEntry("transportId", "foo"),
+				new BdfEntry(MSG_KEY_TRANSPORT_ID, "foo"),
-				new BdfEntry("version", 1),
+				new BdfEntry(MSG_KEY_VERSION, 1),
-				new BdfEntry("local", true)
+				new BdfEntry(MSG_KEY_LOCAL, true)
 		));
 		BdfList fooUpdate = BdfList.of("foo", 1, fooPropertiesDict);
 
@@ -405,28 +409,28 @@ public class TransportPropertyManagerImplTest extends BrambleMockTestCase {
 		List<Contact> contacts = asList(contact1, contact2);
 		Group contactGroup1 = getGroup(CLIENT_ID, MAJOR_VERSION);
 		Group contactGroup2 = getGroup(CLIENT_ID, MAJOR_VERSION);
-		Map<MessageId, BdfDictionary> messageMetadata2 =
+		Map<MessageId, BdfDictionary> messageMetadata =
 				new LinkedHashMap<>();
 		// A remote update for another transport should be ignored
 		MessageId barUpdateId = new MessageId(getRandomId());
-		messageMetadata2.put(barUpdateId, BdfDictionary.of(
+		messageMetadata.put(barUpdateId, BdfDictionary.of(
-				new BdfEntry("transportId", "bar"),
+				new BdfEntry(MSG_KEY_TRANSPORT_ID, "bar"),
-				new BdfEntry("version", 1),
+				new BdfEntry(MSG_KEY_VERSION, 1),
-				new BdfEntry("local", false)
+				new BdfEntry(MSG_KEY_LOCAL, false)
 		));
 		// A local update for the right transport should be ignored
 		MessageId localUpdateId = new MessageId(getRandomId());
-		messageMetadata2.put(localUpdateId, BdfDictionary.of(
+		messageMetadata.put(localUpdateId, BdfDictionary.of(
-				new BdfEntry("transportId", "foo"),
+				new BdfEntry(MSG_KEY_TRANSPORT_ID, "foo"),
-				new BdfEntry("version", 1),
+				new BdfEntry(MSG_KEY_VERSION, 1),
-				new BdfEntry("local", true)
+				new BdfEntry(MSG_KEY_LOCAL, true)
 		));
 		// A remote update for the right transport should be returned
 		MessageId fooUpdateId = new MessageId(getRandomId());
-		messageMetadata2.put(fooUpdateId, BdfDictionary.of(
+		messageMetadata.put(fooUpdateId, BdfDictionary.of(
-				new BdfEntry("transportId", "foo"),
+				new BdfEntry(MSG_KEY_TRANSPORT_ID, "foo"),
-				new BdfEntry("version", 1),
+				new BdfEntry(MSG_KEY_VERSION, 1),
-				new BdfEntry("local", false)
+				new BdfEntry(MSG_KEY_LOCAL, false)
 		));
 		BdfList fooUpdate = BdfList.of("foo", 1, fooPropertiesDict);
 
@@ -440,19 +444,25 @@ public class TransportPropertyManagerImplTest extends BrambleMockTestCase {
 			will(returnValue(contactGroup1));
 			oneOf(clientHelper).getMessageMetadataAsDictionary(txn,
 					contactGroup1.getId());
-			will(returnValue(Collections.emptyMap()));
+			will(returnValue(emptyMap()));
+			oneOf(clientHelper).getGroupMetadataAsDictionary(txn,
+					contactGroup1.getId());
+			will(returnValue(new BdfDictionary()));
 			// Second contact: returns an update
 			oneOf(contactGroupFactory).createContactGroup(CLIENT_ID,
 					MAJOR_VERSION, contact2);
 			will(returnValue(contactGroup2));
 			oneOf(clientHelper).getMessageMetadataAsDictionary(txn,
 					contactGroup2.getId());
-			will(returnValue(messageMetadata2));
+			will(returnValue(messageMetadata));
 			oneOf(clientHelper).getMessageAsList(txn, fooUpdateId);
 			will(returnValue(fooUpdate));
 			oneOf(clientHelper).parseAndValidateTransportProperties(
 					fooPropertiesDict);
 			will(returnValue(fooProperties));
+			oneOf(clientHelper).getGroupMetadataAsDictionary(txn,
+					contactGroup2.getId());
+			will(returnValue(new BdfDictionary()));
 		}});
 
 		TransportPropertyManagerImpl t = createInstance();
@@ -463,6 +473,62 @@ public class TransportPropertyManagerImplTest extends BrambleMockTestCase {
 		assertEquals(fooProperties, properties.get(contact2.getId()));
 	}
 
+	@Test
+	public void testReceivePropertiesOverrideDiscoveredProperties()
+			throws Exception {
+		Transaction txn = new Transaction(null, true);
+		Contact contact = getContact();
+		List<Contact> contacts = singletonList(contact);
+		Group contactGroup = getGroup(CLIENT_ID, MAJOR_VERSION);
+		MessageId updateId = new MessageId(getRandomId());
+		Map<MessageId, BdfDictionary> messageMetadata = singletonMap(updateId,
+				BdfDictionary.of(
+						new BdfEntry(MSG_KEY_TRANSPORT_ID, "foo"),
+						new BdfEntry(MSG_KEY_VERSION, 1),
+						new BdfEntry(MSG_KEY_LOCAL, false)
+				));
+		BdfList update = BdfList.of("foo", 1, fooPropertiesDict);
+		TransportProperties discovered = new TransportProperties();
+		discovered.put("fooKey1", "overridden");
+		discovered.put("fooKey3", "fooValue3");
+		BdfDictionary discoveredDict = new BdfDictionary(discovered);
+		BdfDictionary groupMeta = BdfDictionary.of(
+				new BdfEntry(GROUP_KEY_DISCOVERED, discoveredDict)
+		);
+		TransportProperties merged = new TransportProperties();
+		merged.putAll(fooProperties);
+		merged.put("fooKey3", "fooValue3");
+
+		context.checking(new DbExpectations() {{
+			oneOf(db).transactionWithResult(with(true), withDbCallable(txn));
+			oneOf(db).getContacts(txn);
+			will(returnValue(contacts));
+			// One update
+			oneOf(contactGroupFactory).createContactGroup(CLIENT_ID,
+					MAJOR_VERSION, contact);
+			will(returnValue(contactGroup));
+			oneOf(clientHelper).getMessageMetadataAsDictionary(txn,
+					contactGroup.getId());
+			will(returnValue(messageMetadata));
+			oneOf(clientHelper).getMessageAsList(txn, updateId);
+			will(returnValue(update));
+			oneOf(clientHelper).parseAndValidateTransportProperties(
+					fooPropertiesDict);
+			will(returnValue(fooProperties));
+			oneOf(clientHelper).getGroupMetadataAsDictionary(txn,
+					contactGroup.getId());
+			will(returnValue(groupMeta));
+			oneOf(clientHelper).parseAndValidateTransportProperties(
+					discoveredDict);
+			will(returnValue(discovered));
+		}});
+
+		TransportPropertyManagerImpl t = createInstance();
+		Map<ContactId, TransportProperties> properties =
+				t.getRemoteProperties(new TransportId("foo"));
+		assertEquals(merged, properties.get(contact.getId()));
+	}
+
 	@Test
 	public void testMergingUnchangedPropertiesDoesNotCreateUpdate()
 			throws Exception {
@@ -470,9 +536,9 @@ public class TransportPropertyManagerImplTest extends BrambleMockTestCase {
 		MessageId updateId = new MessageId(getRandomId());
 		Map<MessageId, BdfDictionary> messageMetadata = singletonMap(updateId,
 				BdfDictionary.of(
-						new BdfEntry("transportId", "foo"),
+						new BdfEntry(MSG_KEY_TRANSPORT_ID, "foo"),
-						new BdfEntry("version", 1),
+						new BdfEntry(MSG_KEY_VERSION, 1),
-						new BdfEntry("local", true)
+						new BdfEntry(MSG_KEY_LOCAL, true)
 				));
 		BdfList update = BdfList.of("foo", 1, fooPropertiesDict);
 
@@ -505,7 +571,7 @@ public class TransportPropertyManagerImplTest extends BrambleMockTestCase {
 			// There are no existing properties to merge with
 			oneOf(clientHelper).getMessageMetadataAsDictionary(txn,
 					localGroup.getId());
-			will(returnValue(Collections.emptyMap()));
+			will(returnValue(emptyMap()));
 			// Store the new properties in the local group, version 1
 			expectStoreMessage(txn, localGroup.getId(), "foo",
 					fooPropertiesDict, 1, true, false);
@@ -517,7 +583,7 @@ public class TransportPropertyManagerImplTest extends BrambleMockTestCase {
 			will(returnValue(contactGroup));
 			oneOf(clientHelper).getMessageMetadataAsDictionary(txn,
 					contactGroup.getId());
-			will(returnValue(Collections.emptyMap()));
+			will(returnValue(emptyMap()));
 			expectStoreMessage(txn, contactGroup.getId(), "foo",
 					fooPropertiesDict, 1, true, true);
 		}});
@@ -532,9 +598,9 @@ public class TransportPropertyManagerImplTest extends BrambleMockTestCase {
 		Contact contact = getContact();
 		Group contactGroup = getGroup(CLIENT_ID, MAJOR_VERSION);
 		BdfDictionary oldMetadata = BdfDictionary.of(
-				new BdfEntry("transportId", "foo"),
+				new BdfEntry(MSG_KEY_TRANSPORT_ID, "foo"),
-				new BdfEntry("version", 1),
+				new BdfEntry(MSG_KEY_VERSION, 1),
-				new BdfEntry("local", true)
+				new BdfEntry(MSG_KEY_LOCAL, true)
 		);
 		MessageId localGroupUpdateId = new MessageId(getRandomId());
 		Map<MessageId, BdfDictionary> localGroupMessageMetadata =
@@ -589,14 +655,14 @@ public class TransportPropertyManagerImplTest extends BrambleMockTestCase {
 		// The latest update for transport "foo" should be returned
 		MessageId fooVersion999 = new MessageId(getRandomId());
 		messageMetadata.put(fooVersion999, BdfDictionary.of(
-				new BdfEntry("transportId", "foo"),
+				new BdfEntry(MSG_KEY_TRANSPORT_ID, "foo"),
-				new BdfEntry("version", 999)
+				new BdfEntry(MSG_KEY_VERSION, 999)
 		));
 		// The latest update for transport "bar" should be returned
 		MessageId barVersion3 = new MessageId(getRandomId());
 		messageMetadata.put(barVersion3, BdfDictionary.of(
-				new BdfEntry("transportId", "bar"),
+				new BdfEntry(MSG_KEY_TRANSPORT_ID, "bar"),
-				new BdfEntry("version", 3)
+				new BdfEntry(MSG_KEY_VERSION, 3)
 		));
 		BdfList fooUpdate = BdfList.of("foo", 999, fooPropertiesDict);
 		BdfList barUpdate = BdfList.of("bar", 3, barPropertiesDict);
@@ -627,9 +693,9 @@ public class TransportPropertyManagerImplTest extends BrambleMockTestCase {
 		Message message = getMessage(g);
 		long timestamp = message.getTimestamp();
 		BdfDictionary meta = BdfDictionary.of(
-				new BdfEntry("transportId", transportId),
+				new BdfEntry(MSG_KEY_TRANSPORT_ID, transportId),
-				new BdfEntry("version", version),
+				new BdfEntry(MSG_KEY_VERSION, version),
-				new BdfEntry("local", local)
+				new BdfEntry(MSG_KEY_LOCAL, local)
 		);
 
 		context.checking(new Expectations() {{

bramble-core/src/test/java/org/briarproject/bramble/rendezvous/RendezvousPollerImplTest.java

@@ -17,8 +17,8 @@ import org.briarproject.bramble.api.plugin.ConnectionManager;
 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.event.TransportActiveEvent;
+import org.briarproject.bramble.api.plugin.event.TransportDisabledEvent;
-import org.briarproject.bramble.api.plugin.event.TransportInactiveEvent;
+import org.briarproject.bramble.api.plugin.event.TransportEnabledEvent;
 import org.briarproject.bramble.api.properties.TransportProperties;
 import org.briarproject.bramble.api.rendezvous.KeyMaterialSource;
 import org.briarproject.bramble.api.rendezvous.RendezvousEndpoint;
@@ -49,7 +49,7 @@ import static org.briarproject.bramble.api.contact.PendingContactState.OFFLINE;
 import static org.briarproject.bramble.api.contact.PendingContactState.WAITING_FOR_CONNECTION;
 import static org.briarproject.bramble.rendezvous.RendezvousConstants.POLLING_INTERVAL_MS;
 import static org.briarproject.bramble.rendezvous.RendezvousConstants.RENDEZVOUS_TIMEOUT_MS;
-import static org.briarproject.bramble.test.ListMatcher.listOf;
+import static org.briarproject.bramble.test.CollectionMatcher.collectionOf;
 import static org.briarproject.bramble.test.PairMatcher.pairOf;
 import static org.briarproject.bramble.test.TestUtils.getAgreementPrivateKey;
 import static org.briarproject.bramble.test.TestUtils.getAgreementPublicKey;
@@ -178,10 +178,10 @@ public class RendezvousPollerImplTest extends BrambleMockTestCase {
 		rendezvousPoller.startService();
 		context.assertIsSatisfied();
 
-		// Activate the transport - no endpoints should be created yet
+		// Enable the transport - no endpoints should be created yet
 		expectGetPlugin();
 
-		rendezvousPoller.eventOccurred(new TransportActiveEvent(transportId));
+		rendezvousPoller.eventOccurred(new TransportEnabledEvent(transportId));
 		context.assertIsSatisfied();
 
 		// Add the pending contact - endpoint should be created and polled
@@ -196,7 +196,7 @@ public class RendezvousPollerImplTest extends BrambleMockTestCase {
 			oneOf(clock).currentTimeMillis();
 			will(returnValue(beforeExpiry));
 			oneOf(eventBus).broadcast(with(any(RendezvousPollEvent.class)));
-			oneOf(plugin).poll(with(listOf(pairOf(
+			oneOf(plugin).poll(with(collectionOf(pairOf(
 					equal(transportProperties),
 					any(ConnectionHandler.class)))));
 		}});
@@ -212,8 +212,8 @@ public class RendezvousPollerImplTest extends BrambleMockTestCase {
 				new PendingContactRemovedEvent(pendingContact.getId()));
 		context.assertIsSatisfied();
 
-		// Deactivate the transport - endpoint is already closed
+		// Disable the transport - endpoint is already closed
-		rendezvousPoller.eventOccurred(new TransportInactiveEvent(transportId));
+		rendezvousPoller.eventOccurred(new TransportDisabledEvent(transportId));
 	}
 
 	@Test
@@ -230,10 +230,10 @@ public class RendezvousPollerImplTest extends BrambleMockTestCase {
 		rendezvousPoller.startService();
 		context.assertIsSatisfied();
 
-		// Activate the transport - no endpoints should be created yet
+		// Enable the transport - no endpoints should be created yet
 		expectGetPlugin();
 
-		rendezvousPoller.eventOccurred(new TransportActiveEvent(transportId));
+		rendezvousPoller.eventOccurred(new TransportEnabledEvent(transportId));
 		context.assertIsSatisfied();
 
 		// Add the pending contact - endpoint should be created and polled
@@ -248,7 +248,7 @@ public class RendezvousPollerImplTest extends BrambleMockTestCase {
 			oneOf(clock).currentTimeMillis();
 			will(returnValue(beforeExpiry));
 			oneOf(eventBus).broadcast(with(any(RendezvousPollEvent.class)));
-			oneOf(plugin).poll(with(listOf(pairOf(
+			oneOf(plugin).poll(with(collectionOf(pairOf(
 					equal(transportProperties),
 					any(ConnectionHandler.class)))));
 		}});
@@ -269,12 +269,12 @@ public class RendezvousPollerImplTest extends BrambleMockTestCase {
 				new PendingContactRemovedEvent(pendingContact.getId()));
 		context.assertIsSatisfied();
 
-		// Deactivate the transport - endpoint is already closed
+		// Disable the transport - endpoint is already closed
-		rendezvousPoller.eventOccurred(new TransportInactiveEvent(transportId));
+		rendezvousPoller.eventOccurred(new TransportDisabledEvent(transportId));
 	}
 
 	@Test
-	public void testCreatesAndClosesEndpointsWhenTransportIsActivatedAndDeactivated()
+	public void testCreatesAndClosesEndpointsWhenTransportIsEnabledAndDisabled()
 			throws Exception {
 		long beforeExpiry = pendingContact.getTimestamp();
 
@@ -292,19 +292,19 @@ public class RendezvousPollerImplTest extends BrambleMockTestCase {
 				new PendingContactAddedEvent(pendingContact));
 		context.assertIsSatisfied();
 
-		// Activate the transport - endpoint should be created
+		// Enable the transport - endpoint should be created
 		expectGetPlugin();
 		expectCreateEndpoint();
 		expectStateChangedEvent(WAITING_FOR_CONNECTION);
 
-		rendezvousPoller.eventOccurred(new TransportActiveEvent(transportId));
+		rendezvousPoller.eventOccurred(new TransportEnabledEvent(transportId));
 		context.assertIsSatisfied();
 
-		// Deactivate the transport - endpoint should be closed
+		// Disable the transport - endpoint should be closed
 		expectCloseEndpoint();
 		expectStateChangedEvent(OFFLINE);
 
-		rendezvousPoller.eventOccurred(new TransportInactiveEvent(transportId));
+		rendezvousPoller.eventOccurred(new TransportDisabledEvent(transportId));
 		context.assertIsSatisfied();
 
 		// Remove the pending contact - endpoint is already closed

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

@@ -4,6 +4,7 @@ import org.briarproject.bramble.api.contact.ContactId;
 import org.briarproject.bramble.api.db.DatabaseComponent;
 import org.briarproject.bramble.api.db.Transaction;
 import org.briarproject.bramble.api.event.EventBus;
+import org.briarproject.bramble.api.plugin.TransportId;
 import org.briarproject.bramble.api.sync.Ack;
 import org.briarproject.bramble.api.sync.GroupId;
 import org.briarproject.bramble.api.sync.Message;
@@ -23,6 +24,7 @@ import static org.briarproject.bramble.api.sync.SyncConstants.MAX_MESSAGE_IDS;
 import static org.briarproject.bramble.test.TestUtils.getContactId;
 import static org.briarproject.bramble.test.TestUtils.getMessage;
 import static org.briarproject.bramble.test.TestUtils.getRandomId;
+import static org.briarproject.bramble.test.TestUtils.getTransportId;
 
 public class SimplexOutgoingSessionTest extends BrambleMockTestCase {
 
@@ -36,14 +38,15 @@ public class SimplexOutgoingSessionTest extends BrambleMockTestCase {
 
 	private final Executor dbExecutor = new ImmediateExecutor();
 	private final ContactId contactId = getContactId();
+	private final TransportId transportId = getTransportId();
 	private final Message message = getMessage(new GroupId(getRandomId()));
 	private final MessageId messageId = message.getId();
 
 	@Test
 	public void testNothingToSend() throws Exception {
 		SimplexOutgoingSession session = new SimplexOutgoingSession(db,
-				dbExecutor, eventBus, contactId, MAX_LATENCY, streamWriter,
+				dbExecutor, eventBus, contactId, transportId, MAX_LATENCY,
-				recordWriter);
+				streamWriter, recordWriter);
 		Transaction noAckTxn = new Transaction(null, false);
 		Transaction noMsgTxn = new Transaction(null, false);
 
@@ -76,8 +79,8 @@ public class SimplexOutgoingSessionTest extends BrambleMockTestCase {
 	public void testSomethingToSend() throws Exception {
 		Ack ack = new Ack(singletonList(messageId));
 		SimplexOutgoingSession session = new SimplexOutgoingSession(db,
-				dbExecutor, eventBus, contactId, MAX_LATENCY, streamWriter,
+				dbExecutor, eventBus, contactId, transportId, MAX_LATENCY,
-				recordWriter);
+				streamWriter, recordWriter);
 		Transaction ackTxn = new Transaction(null, false);
 		Transaction noAckTxn = new Transaction(null, false);
 		Transaction msgTxn = new Transaction(null, false);

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

@@ -5,24 +5,24 @@ import org.hamcrest.BaseMatcher;
 import org.hamcrest.Description;
 import org.hamcrest.Matcher;
 
-import java.util.List;
+import java.util.Collection;
 
 import javax.annotation.Nullable;
 
 @NotNullByDefault
-public class ListMatcher<T> extends BaseMatcher<List<T>> {
+public class CollectionMatcher<T> extends BaseMatcher<Collection<T>> {
 
 	private final Matcher<T> elementMatcher;
 
-	public ListMatcher(Matcher<T> elementMatcher) {
+	public CollectionMatcher(Matcher<T> elementMatcher) {
 		this.elementMatcher = elementMatcher;
 	}
 
 	@Override
 	public boolean matches(@Nullable Object item) {
-		if (!(item instanceof List)) return false;
+		if (!(item instanceof Collection)) return false;
-		List list = (List) item;
+		Collection collection = (Collection) item;
-		for (Object element : list) {
+		for (Object element : collection) {
 			if (!elementMatcher.matches(element)) return false;
 		}
 		return true;
@@ -33,7 +33,7 @@ public class ListMatcher<T> extends BaseMatcher<List<T>> {
 		description.appendText("matches a collection");
 	}
 
-	public static <T> ListMatcher<T> listOf(Matcher<T> t) {
+	public static <T> CollectionMatcher<T> collectionOf(Matcher<T> t) {
-		return new ListMatcher<>(t);
+		return new CollectionMatcher<>(t);
 	}
 }

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

@@ -4,6 +4,7 @@ import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.TransportConnectionReader;
 import org.briarproject.bramble.api.plugin.TransportConnectionWriter;
 import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
+import org.briarproject.bramble.api.properties.TransportProperties;
 
 import java.io.IOException;
 import java.io.InputStream;
@@ -37,6 +38,11 @@ public class TestDuplexTransportConnection
 		return writer;
 	}
 
+	@Override
+	public TransportProperties getRemoteProperties() {
+		return new TransportProperties();
+	}
+
 	/**
 	 * Creates and returns a pair of TestDuplexTransportConnections that are
 	 * connected to each other.

bramble-java/build.gradle

@@ -16,7 +16,7 @@ dependencies {
 	implementation fileTree(dir: 'libs', include: '*.jar')
 	implementation 'net.java.dev.jna:jna:4.5.2'
 	implementation 'net.java.dev.jna:jna-platform:4.5.2'
-	tor 'org.briarproject:tor:0.3.5.9@zip'
+	tor 'org.briarproject:tor:0.3.5.10@zip'
 	tor 'org.briarproject:obfs4proxy:0.0.7@zip'
 
 	annotationProcessor 'com.google.dagger:dagger-compiler:2.24'

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

@@ -1,6 +1,7 @@
 package org.briarproject.bramble.plugin;
 
 import org.briarproject.bramble.api.event.EventBus;
+import org.briarproject.bramble.api.io.TimeoutMonitor;
 import org.briarproject.bramble.api.lifecycle.IoExecutor;
 import org.briarproject.bramble.api.lifecycle.ShutdownManager;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
@@ -9,6 +10,7 @@ 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.api.system.Clock;
 import org.briarproject.bramble.plugin.bluetooth.JavaBluetoothPluginFactory;
 import org.briarproject.bramble.plugin.modem.ModemPluginFactory;
 import org.briarproject.bramble.plugin.tcp.LanTcpPluginFactory;
@@ -31,15 +33,16 @@ public class DesktopPluginModule extends PluginModule {
 	PluginConfig getPluginConfig(@IoExecutor Executor ioExecutor,
 			SecureRandom random, BackoffFactory backoffFactory,
 			ReliabilityLayerFactory reliabilityFactory,
-			ShutdownManager shutdownManager, EventBus eventBus) {
+			ShutdownManager shutdownManager, EventBus eventBus, Clock clock,
-		DuplexPluginFactory bluetooth =
+			TimeoutMonitor timeoutMonitor) {
-				new JavaBluetoothPluginFactory(ioExecutor, random, eventBus,
+		DuplexPluginFactory bluetooth = new JavaBluetoothPluginFactory(
-						backoffFactory);
+				ioExecutor, random, eventBus, clock, timeoutMonitor,
+				backoffFactory);
 		DuplexPluginFactory modem = new ModemPluginFactory(ioExecutor,
 				reliabilityFactory);
-		DuplexPluginFactory lan = new LanTcpPluginFactory(ioExecutor, eventBus,
+		DuplexPluginFactory lan = new LanTcpPluginFactory(ioExecutor,
 				backoffFactory);
-		DuplexPluginFactory wan = new WanTcpPluginFactory(ioExecutor, eventBus,
+		DuplexPluginFactory wan = new WanTcpPluginFactory(ioExecutor,
 				backoffFactory, shutdownManager);
 		Collection<DuplexPluginFactory> duplex =
 				asList(bluetooth, modem, lan, wan);

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

@@ -1,5 +1,6 @@
 package org.briarproject.bramble.plugin.bluetooth;
 
+import org.briarproject.bramble.api.io.TimeoutMonitor;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.bramble.api.plugin.Backoff;
@@ -34,10 +35,11 @@ class JavaBluetoothPlugin extends BluetoothPlugin<StreamConnectionNotifier> {
 	private volatile LocalDevice localDevice = null;
 
 	JavaBluetoothPlugin(BluetoothConnectionLimiter connectionManager,
-			Executor ioExecutor, SecureRandom secureRandom,
+			TimeoutMonitor timeoutMonitor, Executor ioExecutor,
-			Backoff backoff, PluginCallback callback, int maxLatency) {
+			SecureRandom secureRandom, Backoff backoff,
-		super(connectionManager, ioExecutor, secureRandom, backoff, callback,
+			PluginCallback callback, int maxLatency, int maxIdleTime) {
-				maxLatency);
+		super(connectionManager, timeoutMonitor, ioExecutor, secureRandom,
+				backoff, callback, maxLatency, maxIdleTime);
 	}
 
 	@Override
@@ -119,7 +121,9 @@ class JavaBluetoothPlugin extends BluetoothPlugin<StreamConnectionNotifier> {
 		return "btspp://" + address + ":" + uuid + ";name=RFCOMM";
 	}
 
-	private DuplexTransportConnection wrapSocket(StreamConnection s) {
+	private DuplexTransportConnection wrapSocket(StreamConnection s)
-		return new JavaBluetoothTransportConnection(this, connectionLimiter, s);
+			throws IOException {
+		return new JavaBluetoothTransportConnection(this, connectionLimiter,
+				timeoutMonitor, s);
 	}
 }

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

@@ -1,6 +1,7 @@
 package org.briarproject.bramble.plugin.bluetooth;
 
 import org.briarproject.bramble.api.event.EventBus;
+import org.briarproject.bramble.api.io.TimeoutMonitor;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.Backoff;
 import org.briarproject.bramble.api.plugin.BackoffFactory;
@@ -8,6 +9,7 @@ import org.briarproject.bramble.api.plugin.PluginCallback;
 import org.briarproject.bramble.api.plugin.TransportId;
 import org.briarproject.bramble.api.plugin.duplex.DuplexPlugin;
 import org.briarproject.bramble.api.plugin.duplex.DuplexPluginFactory;
+import org.briarproject.bramble.api.system.Clock;
 
 import java.security.SecureRandom;
 import java.util.concurrent.Executor;
@@ -21,22 +23,27 @@ import static org.briarproject.bramble.api.plugin.BluetoothConstants.ID;
 public class JavaBluetoothPluginFactory implements DuplexPluginFactory {
 
 	private static final int MAX_LATENCY = 30 * 1000; // 30 seconds
+	private static final int MAX_IDLE_TIME = 30 * 1000; // 30 seconds
 	private static final int MIN_POLLING_INTERVAL = 60 * 1000; // 1 minute
 	private static final int MAX_POLLING_INTERVAL = 10 * 60 * 1000; // 10 mins
 	private static final double BACKOFF_BASE = 1.2;
 
 	private final Executor ioExecutor;
 	private final SecureRandom secureRandom;
-	private final BackoffFactory backoffFactory;
 	private final EventBus eventBus;
+	private final Clock clock;
+	private final TimeoutMonitor timeoutMonitor;
+	private final BackoffFactory backoffFactory;
 
 	public JavaBluetoothPluginFactory(Executor ioExecutor,
-			SecureRandom secureRandom, EventBus eventBus,
+			SecureRandom secureRandom, EventBus eventBus, Clock clock,
-			BackoffFactory backoffFactory) {
+			TimeoutMonitor timeoutMonitor, BackoffFactory backoffFactory) {
 		this.ioExecutor = ioExecutor;
 		this.secureRandom = secureRandom;
-		this.backoffFactory = backoffFactory;
 		this.eventBus = eventBus;
+		this.clock = clock;
+		this.timeoutMonitor = timeoutMonitor;
+		this.backoffFactory = backoffFactory;
 	}
 
 	@Override
@@ -52,11 +59,12 @@ public class JavaBluetoothPluginFactory implements DuplexPluginFactory {
 	@Override
 	public DuplexPlugin createPlugin(PluginCallback callback) {
 		BluetoothConnectionLimiter connectionLimiter =
-				new BluetoothConnectionLimiterImpl();
+				new BluetoothConnectionLimiterImpl(eventBus, clock);
 		Backoff backoff = backoffFactory.createBackoff(MIN_POLLING_INTERVAL,
 				MAX_POLLING_INTERVAL, BACKOFF_BASE);
 		JavaBluetoothPlugin plugin = new JavaBluetoothPlugin(connectionLimiter,
-				ioExecutor, secureRandom, backoff, callback, MAX_LATENCY);
+				timeoutMonitor, ioExecutor, secureRandom, backoff, callback,
+				MAX_LATENCY, MAX_IDLE_TIME);
 		eventBus.addListener(plugin);
 		return plugin;
 	}

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

@@ -1,5 +1,6 @@
 package org.briarproject.bramble.plugin.bluetooth;
 
+import org.briarproject.bramble.api.io.TimeoutMonitor;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.Plugin;
 import org.briarproject.bramble.api.plugin.duplex.AbstractDuplexTransportConnection;
@@ -14,20 +15,24 @@ import javax.microedition.io.StreamConnection;
 class JavaBluetoothTransportConnection
 		extends AbstractDuplexTransportConnection {
 
-	private final BluetoothConnectionLimiter connectionManager;
+	private final BluetoothConnectionLimiter connectionLimiter;
 	private final StreamConnection stream;
+	private final InputStream in;
 
 	JavaBluetoothTransportConnection(Plugin plugin,
-			BluetoothConnectionLimiter connectionManager,
+			BluetoothConnectionLimiter connectionLimiter,
-			StreamConnection stream) {
+			TimeoutMonitor timeoutMonitor,
+			StreamConnection stream) throws IOException {
 		super(plugin);
+		this.connectionLimiter = connectionLimiter;
 		this.stream = stream;
-		this.connectionManager = connectionManager;
+		in = timeoutMonitor.createTimeoutInputStream(
+				stream.openInputStream(), plugin.getMaxIdleTime() * 2);
 	}
 
 	@Override
-	protected InputStream getInputStream() throws IOException {
+	protected InputStream getInputStream() {
-		return stream.openInputStream();
+		return in;
 	}
 
 	@Override
@@ -40,7 +45,7 @@ class JavaBluetoothTransportConnection
 		try {
 			stream.close();
 		} finally {
-			connectionManager.connectionClosed(this);
+			connectionLimiter.connectionClosed(this, exception);
 		}
 	}
 }

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

@@ -4,10 +4,8 @@ import org.briarproject.bramble.api.Pair;
 import org.briarproject.bramble.api.data.BdfList;
 import org.briarproject.bramble.api.keyagreement.KeyAgreementListener;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.bramble.api.plugin.ConnectionHandler;
-import org.briarproject.bramble.api.plugin.DiscoveryHandler;
 import org.briarproject.bramble.api.plugin.PluginCallback;
 import org.briarproject.bramble.api.plugin.PluginException;
 import org.briarproject.bramble.api.plugin.TransportId;
@@ -21,20 +19,13 @@ import org.briarproject.bramble.api.rendezvous.RendezvousEndpoint;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
-import java.util.List;
+import java.util.Collection;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.logging.Logger;
 
-import javax.annotation.concurrent.GuardedBy;
-import javax.annotation.concurrent.ThreadSafe;
-
 import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
 import static java.util.logging.Logger.getLogger;
-import static org.briarproject.bramble.api.plugin.Plugin.State.ACTIVE;
-import static org.briarproject.bramble.api.plugin.Plugin.State.ENABLING;
-import static org.briarproject.bramble.api.plugin.Plugin.State.INACTIVE;
-import static org.briarproject.bramble.api.plugin.Plugin.State.STARTING_STOPPING;
 import static org.briarproject.bramble.util.LogUtils.logException;
 import static org.briarproject.bramble.util.StringUtils.isNullOrEmpty;
 
@@ -53,8 +44,8 @@ class ModemPlugin implements DuplexPlugin, Modem.Callback {
 	private final PluginCallback callback;
 	private final int maxLatency;
 	private final AtomicBoolean used = new AtomicBoolean(false);
-	private final PluginState state = new PluginState();
 
+	private volatile boolean running = false;
 	private volatile Modem modem = null;
 
 	ModemPlugin(ModemFactory modemFactory, SerialPortList serialPortList,
@@ -84,7 +75,6 @@ class ModemPlugin implements DuplexPlugin, Modem.Callback {
 	@Override
 	public void start() throws PluginException {
 		if (used.getAndSet(true)) throw new IllegalStateException();
-		state.setStarted();
 		for (String portName : serialPortList.getPortNames()) {
 			if (LOG.isLoggable(INFO))
 				LOG.info("Trying to initialise modem on " + portName);
@@ -93,20 +83,18 @@ class ModemPlugin implements DuplexPlugin, Modem.Callback {
 				if (!modem.start()) continue;
 				if (LOG.isLoggable(INFO))
 					LOG.info("Initialised modem on " + portName);
-				state.setInitialised();
+				running = true;
 				return;
 			} catch (IOException e) {
 				logException(LOG, WARNING, e);
 			}
 		}
-		LOG.warning("Failed to initialised modem");
-		state.setFailed();
 		throw new PluginException();
 	}
 
 	@Override
 	public void stop() {
-		state.setStopped();
+		running = false;
 		if (modem != null) {
 			try {
 				modem.stop();
@@ -117,13 +105,8 @@ class ModemPlugin implements DuplexPlugin, Modem.Callback {
 	}
 
 	@Override
-	public State getState() {
+	public boolean isRunning() {
-		return state.getState();
+		return running;
-	}
-
-	@Override
-	public int getReasonsDisabled() {
-		return 0;
 	}
 
 	@Override
@@ -137,13 +120,13 @@ class ModemPlugin implements DuplexPlugin, Modem.Callback {
 	}
 
 	@Override
-	public void poll(
+	public void poll(Collection<Pair<TransportProperties, ConnectionHandler>>
-			List<Pair<TransportProperties, ConnectionHandler>> properties) {
+			properties) {
 		throw new UnsupportedOperationException();
 	}
 
-	private void resetModem() {
+	private boolean resetModem() {
-		if (getState() != ACTIVE) return;
+		if (!running) return false;
 		for (String portName : serialPortList.getPortNames()) {
 			if (LOG.isLoggable(INFO))
 				LOG.info("Trying to initialise modem on " + portName);
@@ -152,18 +135,18 @@ class ModemPlugin implements DuplexPlugin, Modem.Callback {
 				if (!modem.start()) continue;
 				if (LOG.isLoggable(INFO))
 					LOG.info("Initialised modem on " + portName);
-				return;
+				return true;
 			} catch (IOException e) {
 				logException(LOG, WARNING, e);
 			}
 		}
-		LOG.warning("Failed to initialise modem");
+		running = false;
-		state.setFailed();
+		return false;
 	}
 
 	@Override
 	public DuplexTransportConnection createConnection(TransportProperties p) {
-		if (getState() != ACTIVE) return null;
+		if (!running) return null;
 		// Get the ISO 3166 code for the caller's country
 		String fromIso = callback.getLocalProperties().get("iso3166");
 		if (isNullOrEmpty(fromIso)) return null;
@@ -214,17 +197,6 @@ class ModemPlugin implements DuplexPlugin, Modem.Callback {
 		throw new UnsupportedOperationException();
 	}
 
-	@Override
-	public boolean supportsDiscovery() {
-		return false;
-	}
-
-	@Override
-	public void discoverPeers(
-			List<Pair<TransportProperties, DiscoveryHandler>> properties) {
-		throw new UnsupportedOperationException();
-	}
-
 	@Override
 	public void incomingCallConnected() {
 		LOG.info("Incoming call connected");
@@ -260,41 +232,4 @@ class ModemPlugin implements DuplexPlugin, Modem.Callback {
 			if (exception) resetModem();
 		}
 	}
-
-	@ThreadSafe
-	@NotNullByDefault
-	private class PluginState {
-
-		@GuardedBy("this")
-		private boolean started = false,
-				stopped = false,
-				initialised = false,
-				failed = false;
-
-		private synchronized void setStarted() {
-			started = true;
-			callback.pluginStateChanged(getState());
-		}
-
-		private synchronized void setStopped() {
-			stopped = true;
-			callback.pluginStateChanged(getState());
-		}
-
-		private synchronized void setInitialised() {
-			initialised = true;
-			callback.pluginStateChanged(getState());
-		}
-
-		private synchronized void setFailed() {
-			failed = true;
-			callback.pluginStateChanged(getState());
-		}
-
-		private State getState() {
-			if (!started || stopped) return STARTING_STOPPING;
-			if (failed) return INACTIVE;
-			return initialised ? ACTIVE : ENABLING;
-		}
-	}
 }

bramble-java/src/test/java/org/briarproject/bramble/plugin/modem/ModemPluginTest.java

@@ -9,8 +9,6 @@ import org.junit.Test;
 
 import java.io.IOException;
 
-import static org.briarproject.bramble.api.plugin.Plugin.State.ACTIVE;
-import static org.briarproject.bramble.api.plugin.Plugin.State.ENABLING;
 import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertNull;
 
@@ -35,7 +33,6 @@ public class ModemPluginTest extends BrambleMockTestCase {
 	@Test
 	public void testModemCreation() throws Exception {
 		context.checking(new Expectations() {{
-			oneOf(callback).pluginStateChanged(ENABLING);
 			oneOf(serialPortList).getPortNames();
 			will(returnValue(new String[] {"foo", "bar", "baz"}));
 			// First call to createModem() returns false
@@ -53,7 +50,6 @@ public class ModemPluginTest extends BrambleMockTestCase {
 			will(returnValue(modem));
 			oneOf(modem).start();
 			will(returnValue(true));
-			oneOf(callback).pluginStateChanged(ACTIVE);
 		}});
 
 		plugin.start();
@@ -69,14 +65,12 @@ public class ModemPluginTest extends BrambleMockTestCase {
 
 		context.checking(new Expectations() {{
 			// start()
-			oneOf(callback).pluginStateChanged(ENABLING);
 			oneOf(serialPortList).getPortNames();
 			will(returnValue(new String[] {"foo"}));
 			oneOf(modemFactory).createModem(plugin, "foo");
 			will(returnValue(modem));
 			oneOf(modem).start();
 			will(returnValue(true));
-			oneOf(callback).pluginStateChanged(ACTIVE);
 			// createConnection()
 			oneOf(callback).getLocalProperties();
 			will(returnValue(local));
@@ -99,14 +93,12 @@ public class ModemPluginTest extends BrambleMockTestCase {
 
 		context.checking(new Expectations() {{
 			// start()
-			oneOf(callback).pluginStateChanged(ENABLING);
 			oneOf(serialPortList).getPortNames();
 			will(returnValue(new String[] {"foo"}));
 			oneOf(modemFactory).createModem(plugin, "foo");
 			will(returnValue(modem));
 			oneOf(modem).start();
 			will(returnValue(true));
-			oneOf(callback).pluginStateChanged(ACTIVE);
 			// createConnection()
 			oneOf(callback).getLocalProperties();
 			will(returnValue(local));
@@ -129,14 +121,12 @@ public class ModemPluginTest extends BrambleMockTestCase {
 
 		context.checking(new Expectations() {{
 			// start()
-			oneOf(callback).pluginStateChanged(ENABLING);
 			oneOf(serialPortList).getPortNames();
 			will(returnValue(new String[] {"foo"}));
 			oneOf(modemFactory).createModem(plugin, "foo");
 			will(returnValue(modem));
 			oneOf(modem).start();
 			will(returnValue(true));
-			oneOf(callback).pluginStateChanged(ACTIVE);
 			// createConnection()
 			oneOf(callback).getLocalProperties();
 			will(returnValue(local));

bramble-java/src/test/java/org/briarproject/bramble/plugin/tor/BridgeTest.java

@@ -32,7 +32,6 @@ import javax.net.SocketFactory;
 import static java.util.Collections.singletonList;
 import static java.util.concurrent.TimeUnit.SECONDS;
 import static java.util.logging.Logger.getLogger;
-import static org.briarproject.bramble.api.plugin.Plugin.State.ACTIVE;
 import static org.briarproject.bramble.test.TestUtils.deleteTestDirectory;
 import static org.briarproject.bramble.test.TestUtils.getTestDirectory;
 import static org.briarproject.bramble.test.TestUtils.isOptionalTestEnabled;
@@ -142,10 +141,10 @@ public class BridgeTest extends BrambleTestCase {
 			plugin.start();
 			long start = clock.currentTimeMillis();
 			while (clock.currentTimeMillis() - start < TIMEOUT) {
-				if (plugin.getState() == ACTIVE) return;
+				if (plugin.isRunning()) return;
 				clock.sleep(500);
 			}
-			if (plugin.getState() != ACTIVE) {
+			if (!plugin.isRunning()) {
 				fail("Could not connect to Tor within timeout.");
 			}
 		} finally {

bramble-java/src/test/java/org/briarproject/bramble/plugin/tor/TestPluginCallback.java

@@ -1,7 +1,6 @@
 package org.briarproject.bramble.plugin.tor;
 
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.plugin.Plugin.State;
 import org.briarproject.bramble.api.plugin.PluginCallback;
 import org.briarproject.bramble.api.plugin.TransportConnectionReader;
 import org.briarproject.bramble.api.plugin.TransportConnectionWriter;
@@ -31,7 +30,11 @@ public class TestPluginCallback implements PluginCallback {
 	}
 
 	@Override
-	public void pluginStateChanged(State state) {
+	public void transportEnabled() {
+	}
+
+	@Override
+	public void transportDisabled() {
 	}
 
 	@Override

bramble-java/witness.gradle

@@ -24,7 +24,7 @@ dependencyVerification {
         'org.apache.ant:ant:1.9.4:ant-1.9.4.jar:649ae0730251de07b8913f49286d46bba7b92d47c5f332610aa426c4f02161d8',
         'org.beanshell:bsh:1.3.0:bsh-1.3.0.jar:9b04edc75d19db54f1b4e8b5355e9364384c6cf71eb0a1b9724c159d779879f8',
         'org.briarproject:obfs4proxy:0.0.7:obfs4proxy-0.0.7.zip:5b2f693262ce43a7e130f7cc7d5d1617925330640a2eb6d71085e95df8ee0642',
-        'org.briarproject:tor:0.3.5.9:tor-0.3.5.9.zip:6c3994b129db019cc23caaf50d6b4383903c40d05fbc47fc94211170a3e5d38c',
+        'org.briarproject:tor:0.3.5.10:tor-0.3.5.10.zip:7b387d3523ae8af289c23be59dc4c64ec5d3721385d7825a09705095e3318d5c',
         'org.checkerframework:checker-compat-qual:2.5.3:checker-compat-qual-2.5.3.jar:d76b9afea61c7c082908023f0cbc1427fab9abd2df915c8b8a3e7a509bccbc6d',
         'org.checkerframework:checker-qual:2.5.2:checker-qual-2.5.2.jar:64b02691c8b9d4e7700f8ee2e742dce7ea2c6e81e662b7522c9ee3bf568c040a',
         'org.codehaus.mojo:animal-sniffer-annotations:1.17:animal-sniffer-annotations-1.17.jar:92654f493ecfec52082e76354f0ebf87648dc3d5cec2e3c3cdb947c016747a53',

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

@@ -28,7 +28,9 @@ import static android.security.keystore.KeyProperties.PURPOSE_SIGN;
 import static java.util.Arrays.asList;
 import static java.util.Collections.singletonList;
 import static java.util.logging.Level.INFO;
+import static java.util.logging.Level.WARNING;
 import static java.util.logging.Logger.getLogger;
+import static org.briarproject.bramble.util.LogUtils.logException;
 
 @RequiresApi(23)
 @NotNullByDefault
@@ -79,7 +81,10 @@ class AndroidKeyStrengthener implements KeyStrengthener {
 				return true;
 			}
 			return false;
-		} catch (GeneralSecurityException | IOException e) {
+		} catch (GeneralSecurityException e) {
+			logException(LOG, WARNING, e);
+			return false;
+		} catch (IOException e) {
 			throw new RuntimeException(e);
 		}
 	}

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

@@ -14,6 +14,7 @@ import org.briarproject.bramble.api.crypto.KeyStrengthener;
 import org.briarproject.bramble.api.crypto.PublicKey;
 import org.briarproject.bramble.api.db.DatabaseConfig;
 import org.briarproject.bramble.api.event.EventBus;
+import org.briarproject.bramble.api.io.TimeoutMonitor;
 import org.briarproject.bramble.api.lifecycle.IoExecutor;
 import org.briarproject.bramble.api.lifecycle.LifecycleManager;
 import org.briarproject.bramble.api.network.NetworkManager;
@@ -36,7 +37,7 @@ import org.briarproject.bramble.util.AndroidUtils;
 import org.briarproject.bramble.util.StringUtils;
 import org.briarproject.briar.android.account.LockManagerImpl;
 import org.briarproject.briar.android.keyagreement.ContactExchangeModule;
-import org.briarproject.briar.android.navdrawer.NavDrawerModule;
+import org.briarproject.briar.android.login.LoginModule;
 import org.briarproject.briar.android.viewmodel.ViewModelModule;
 import org.briarproject.briar.api.android.AndroidNotificationManager;
 import org.briarproject.briar.api.android.DozeWatchdog;
@@ -66,8 +67,8 @@ import static org.briarproject.bramble.api.reporting.ReportingConstants.DEV_PUBL
 import static org.briarproject.briar.android.TestingConstants.IS_DEBUG_BUILD;
 
 @Module(includes = {
-		NavDrawerModule.class,
 		ContactExchangeModule.class,
+		LoginModule.class,
 		ViewModelModule.class
 })
 public class AppModule {
@@ -122,11 +123,12 @@ public class AppModule {
 			LocationUtils locationUtils, EventBus eventBus,
 			ResourceProvider resourceProvider,
 			CircumventionProvider circumventionProvider,
-			BatteryManager batteryManager, Clock clock) {
+			BatteryManager batteryManager, Clock clock,
+			TimeoutMonitor timeoutMonitor) {
 		Context appContext = app.getApplicationContext();
-		DuplexPluginFactory bluetooth =
+		DuplexPluginFactory bluetooth = new AndroidBluetoothPluginFactory(
-				new AndroidBluetoothPluginFactory(ioExecutor, androidExecutor,
+				ioExecutor, androidExecutor, appContext, random, eventBus,
-						appContext, random, eventBus, clock, backoffFactory);
+				clock, timeoutMonitor, backoffFactory);
 		DuplexPluginFactory tor = new AndroidTorPluginFactory(ioExecutor,
 				scheduler, appContext, networkManager, locationUtils, eventBus,
 				torSocketFactory, backoffFactory, resourceProvider,

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

@@ -8,8 +8,8 @@ import org.briarproject.briar.android.controller.BriarController;
 import org.briarproject.briar.android.controller.BriarControllerImpl;
 import org.briarproject.briar.android.controller.DbController;
 import org.briarproject.briar.android.controller.DbControllerImpl;
-import org.briarproject.briar.android.login.ChangePasswordController;
+import org.briarproject.briar.android.navdrawer.NavDrawerController;
-import org.briarproject.briar.android.login.ChangePasswordControllerImpl;
+import org.briarproject.briar.android.navdrawer.NavDrawerControllerImpl;
 
 import dagger.Module;
 import dagger.Provides;
@@ -44,13 +44,6 @@ public class ActivityModule {
 		return setupController;
 	}
 
-	@ActivityScope
-	@Provides
-	ChangePasswordController providePasswordController(
-			ChangePasswordControllerImpl passwordController) {
-		return passwordController;
-	}
-
 	@ActivityScope
 	@Provides
 	protected BriarController provideBriarController(
@@ -65,10 +58,17 @@ public class ActivityModule {
 		return dbController;
 	}
 
+	@ActivityScope
+	@Provides
+	NavDrawerController provideNavDrawerController(
+			NavDrawerControllerImpl navDrawerController) {
+		activity.addLifecycleController(navDrawerController);
+		return navDrawerController;
+	}
+
 	@ActivityScope
 	@Provides
 	BriarServiceConnection provideBriarServiceConnection() {
 		return new BriarServiceConnection();
 	}
-
 }

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

@@ -92,6 +92,9 @@ public abstract class BaseActivity extends AppCompatActivity
 				.build();
 		injectActivity(activityComponent);
 		super.onCreate(state);
+		if (LOG.isLoggable(INFO)) {
+			LOG.info("Creating " + getClass().getSimpleName());
+		}
 
 		// WARNING: When removing this or making it possible to turn it off,
 		//          we need a solution for the app lock feature.
@@ -127,8 +130,9 @@ public abstract class BaseActivity extends AppCompatActivity
 	@Override
 	protected void onStart() {
 		super.onStart();
-		if (LOG.isLoggable(INFO))
+		if (LOG.isLoggable(INFO)) {
-			LOG.info("Starting " + this.getClass().getSimpleName());
+			LOG.info("Starting " + getClass().getSimpleName());
+		}
 		for (ActivityLifecycleController alc : lifecycleControllers) {
 			alc.onActivityStart();
 		}
@@ -144,11 +148,28 @@ public abstract class BaseActivity extends AppCompatActivity
 		return (ScreenFilterDialogFragment) f;
 	}
 
+	@Override
+	protected void onResume() {
+		super.onResume();
+		if (LOG.isLoggable(INFO)) {
+			LOG.info("Resuming " + getClass().getSimpleName());
+		}
+	}
+
+	@Override
+	protected void onPause() {
+		super.onPause();
+		if (LOG.isLoggable(INFO)) {
+			LOG.info("Pausing " + getClass().getSimpleName());
+		}
+	}
+
 	@Override
 	protected void onStop() {
 		super.onStop();
-		if (LOG.isLoggable(INFO))
+		if (LOG.isLoggable(INFO)) {
-			LOG.info("Stopping " + this.getClass().getSimpleName());
+			LOG.info("Stopping " + getClass().getSimpleName());
+		}
 		for (ActivityLifecycleController alc : lifecycleControllers) {
 			alc.onActivityStop();
 		}
@@ -203,6 +224,9 @@ public abstract class BaseActivity extends AppCompatActivity
 	@Override
 	protected void onDestroy() {
 		super.onDestroy();
+		if (LOG.isLoggable(INFO)) {
+			LOG.info("Destroying " + getClass().getSimpleName());
+		}
 		destroyed = true;
 		for (ActivityLifecycleController alc : lifecycleControllers) {
 			alc.onActivityDestroy();

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

@@ -95,12 +95,14 @@ public abstract class BriarActivity extends BaseActivity {
 			// Also check that the activity isn't finishing already.
 			// This is possible if we finished in onActivityResult().
 			// Launching another StartupActivity would cause a loop.
+			LOG.info("Not signed in, launching StartupActivity");
 			Intent i = new Intent(this, StartupActivity.class);
 			startActivityForResult(i, REQUEST_PASSWORD);
 		} else if (lockManager.isLocked() && !isFinishing()) {
 			// Also check that the activity isn't finishing already.
 			// This is possible if we finished in onActivityResult().
 			// Launching another UnlockActivity would cause a loop.
+			LOG.info("Locked, launching UnlockActivity");
 			Intent i = new Intent(this, UnlockActivity.class);
 			startActivityForResult(i, REQUEST_UNLOCK);
 		} else if (SDK_INT >= 23) {

briar-android/src/main/java/org/briarproject/briar/android/contact/add/remote/NicknameFragment.java

@@ -3,6 +3,7 @@ package org.briarproject.briar.android.contact.add.remote;
 import android.content.Context;
 import android.content.DialogInterface.OnClickListener;
 import android.content.Intent;
+import android.graphics.drawable.Drawable;
 import android.os.Bundle;
 import android.text.Editable;
 import android.view.LayoutInflater;
@@ -37,10 +38,12 @@ import androidx.lifecycle.ViewModelProviders;
 import static android.view.View.INVISIBLE;
 import static android.view.View.VISIBLE;
 import static android.widget.Toast.LENGTH_LONG;
+import static androidx.core.content.ContextCompat.getColor;
+import static androidx.core.content.ContextCompat.getDrawable;
+import static androidx.core.graphics.drawable.DrawableCompat.setTint;
 import static java.util.Objects.requireNonNull;
 import static org.briarproject.bramble.api.identity.AuthorConstants.MAX_AUTHOR_NAME_LENGTH;
 import static org.briarproject.bramble.util.StringUtils.utf8IsTooLong;
-import static org.briarproject.briar.android.util.UiUtils.getDialogIcon;
 
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
@@ -196,7 +199,9 @@ public class NicknameFragment extends BaseFragment {
 	private void showWarningDialog(String name1, String name2) {
 		Context ctx = requireContext();
 		Builder b = new Builder(ctx, R.style.BriarDialogTheme);
-		b.setIcon(getDialogIcon(ctx, R.drawable.alerts_and_states_error));
+		Drawable icon = getDrawable(ctx, R.drawable.alerts_and_states_error);
+		setTint(requireNonNull(icon), getColor(ctx, R.color.color_primary));
+		b.setIcon(icon);
 		b.setTitle(getString(R.string.duplicate_link_dialog_title));
 		b.setMessage(
 				getString(R.string.duplicate_link_dialog_text_3, name1, name2));

briar-android/src/main/java/org/briarproject/briar/android/conversation/ImageActivity.java

@@ -2,6 +2,7 @@ package org.briarproject.briar.android.conversation;
 
 import android.content.DialogInterface.OnClickListener;
 import android.content.Intent;
+import android.graphics.drawable.Drawable;
 import android.os.Bundle;
 import android.transition.Fade;
 import android.transition.Transition;
@@ -34,6 +35,8 @@ import androidx.annotation.Nullable;
 import androidx.annotation.RequiresApi;
 import androidx.appcompat.app.AlertDialog.Builder;
 import androidx.appcompat.widget.Toolbar;
+import androidx.core.content.ContextCompat;
+import androidx.core.graphics.drawable.DrawableCompat;
 import androidx.fragment.app.Fragment;
 import androidx.fragment.app.FragmentManager;
 import androidx.fragment.app.FragmentStatePagerAdapter;
@@ -56,7 +59,6 @@ import static com.google.android.material.snackbar.Snackbar.LENGTH_LONG;
 import static java.util.Objects.requireNonNull;
 import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_SAVE_ATTACHMENT;
 import static org.briarproject.briar.android.util.UiUtils.formatDateAbsolute;
-import static org.briarproject.briar.android.util.UiUtils.getDialogIcon;
 
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
@@ -276,7 +278,10 @@ public class ImageActivity extends BriarActivity
 		Builder builder = new Builder(this, R.style.BriarDialogTheme);
 		builder.setTitle(getString(R.string.dialog_title_save_image));
 		builder.setMessage(getString(R.string.dialog_message_save_image));
-		builder.setIcon(getDialogIcon(this, R.drawable.ic_security));
+		Drawable icon = ContextCompat.getDrawable(this, R.drawable.ic_security);
+		DrawableCompat.setTint(requireNonNull(icon),
+				ContextCompat.getColor(this, R.color.color_primary));
+		builder.setIcon(icon);
 		builder.setPositiveButton(R.string.save_image, okListener);
 		builder.setNegativeButton(R.string.cancel, null);
 		builder.show();

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

@@ -9,7 +9,6 @@ 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;
-import org.briarproject.briar.android.fragment.BaseFragment;
 
 import javax.annotation.Nullable;
 import javax.inject.Inject;
@@ -80,13 +79,13 @@ public class ContactExchangeActivity extends KeyAgreementActivity {
 
 	@UiThread
 	private void contactExchangeFailed() {
-		showErrorFragment();
+		showErrorFragment(R.string.connection_error_explanation);
 	}
 
 	@UiThread
 	@Override
 	public void keyAgreementFailed() {
-		showErrorFragment();
+		showErrorFragment(R.string.connection_error_explanation);
 	}
 
 	@UiThread
@@ -104,7 +103,7 @@ public class ContactExchangeActivity extends KeyAgreementActivity {
 	@UiThread
 	@Override
 	public void keyAgreementAborted(boolean remoteAborted) {
-		showErrorFragment();
+		showErrorFragment(R.string.connection_error_explanation);
 	}
 
 	@UiThread
@@ -113,10 +112,4 @@ public class ContactExchangeActivity extends KeyAgreementActivity {
 		startContactExchange(result);
 		return getString(R.string.exchanging_contact_details);
 	}
-
-	protected void showErrorFragment() {
-		String errorMsg = getString(R.string.connection_error_explanation);
-		BaseFragment f = ContactExchangeErrorFragment.newInstance(errorMsg);
-		showNextFragment(f);
-	}
 }

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

@@ -8,18 +8,10 @@ import android.content.IntentFilter;
 import android.os.Bundle;
 import android.view.MenuItem;
 
-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.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
-import org.briarproject.bramble.api.plugin.BluetoothConstants;
-import org.briarproject.bramble.api.plugin.LanTcpConstants;
-import org.briarproject.bramble.api.plugin.Plugin;
-import org.briarproject.bramble.api.plugin.Plugin.State;
-import org.briarproject.bramble.api.plugin.PluginManager;
 import org.briarproject.bramble.api.plugin.event.BluetoothEnabledEvent;
-import org.briarproject.bramble.api.plugin.event.TransportStateEvent;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.activity.ActivityComponent;
 import org.briarproject.briar.android.activity.BriarActivity;
@@ -45,15 +37,13 @@ import static android.Manifest.permission.ACCESS_COARSE_LOCATION;
 import static android.Manifest.permission.CAMERA;
 import static android.bluetooth.BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE;
 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.STATE_ON;
 import static android.content.pm.PackageManager.PERMISSION_GRANTED;
-import static java.util.logging.Level.INFO;
-import static java.util.logging.Logger.getLogger;
-import static org.briarproject.bramble.api.nullsafety.NullSafety.requireNonNull;
-import static org.briarproject.bramble.api.plugin.Plugin.State.ACTIVE;
-import static org.briarproject.bramble.api.plugin.Plugin.State.DISABLED;
-import static org.briarproject.bramble.api.plugin.Plugin.State.INACTIVE;
-import static org.briarproject.bramble.api.plugin.Plugin.State.STARTING_STOPPING;
 import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_BLUETOOTH_DISCOVERABLE;
 import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_PERMISSION_CAMERA_LOCATION;
 
@@ -61,33 +51,10 @@ import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_PERMI
 @ParametersNotNullByDefault
 public abstract class KeyAgreementActivity extends BriarActivity implements
 		BaseFragmentListener, IntroScreenSeenListener,
-		KeyAgreementEventListener, EventListener {
+		KeyAgreementEventListener {
 
-	private enum BluetoothDecision {
+	private enum BluetoothState {
-		/**
+		UNKNOWN, NO_ADAPTER, WAITING, REFUSED, ENABLED, DISCOVERABLE
-		 * We haven't asked the user about Bluetooth discoverability.
-		 */
-		UNKNOWN,
-
-		/**
-		 * The device doesn't have a Bluetooth adapter.
-		 */
-		NO_ADAPTER,
-
-		/**
-		 * We're waiting for the user to accept or refuse discoverability.
-		 */
-		WAITING,
-
-		/**
-		 * The user has accepted discoverability.
-		 */
-		ACCEPTED,
-
-		/**
-		 * The user has refused discoverability.
-		 */
-		REFUSED
 	}
 
 	private enum Permission {
@@ -95,14 +62,11 @@ public abstract class KeyAgreementActivity extends BriarActivity implements
 	}
 
 	private static final Logger LOG =
-			getLogger(KeyAgreementActivity.class.getName());
+			Logger.getLogger(KeyAgreementActivity.class.getName());
 
 	@Inject
 	EventBus eventBus;
 
-	@Inject
-	PluginManager pluginManager;
-
 	/**
 	 * Set to true in onPostResume() and false in onPause(). This prevents the
 	 * QR code fragment from being shown if onRequestPermissionsResult() is
@@ -110,36 +74,21 @@ public abstract class KeyAgreementActivity extends BriarActivity implements
 	 * https://issuetracker.google.com/issues/37067655.
 	 */
 	private boolean isResumed = false;
-
 	/**
 	 * Set to true when the continue button is clicked, and false when the QR
 	 * code fragment is shown. This prevents the QR code fragment from being
 	 * shown automatically before the continue button has been clicked.
 	 */
 	private boolean continueClicked = false;
-
 	/**
 	 * Records whether the Bluetooth adapter was already enabled before we
 	 * asked for Bluetooth discoverability, so we know whether to broadcast a
 	 * {@link BluetoothEnabledEvent}.
 	 */
 	private boolean wasAdapterEnabled = false;
-
-	/**
-	 * Records whether we've enabled the wifi plugin so we don't enable it more
-	 * than once.
-	 */
-	private boolean hasEnabledWifi = false;
-
-	/**
-	 * Records whether we've enabled the Bluetooth plugin so we don't enable it
-	 * more than once.
-	 */
-	private boolean hasEnabledBluetooth = false;
-
 	private Permission cameraPermission = Permission.UNKNOWN;
 	private Permission locationPermission = Permission.UNKNOWN;
-	private BluetoothDecision bluetoothDecision = BluetoothDecision.UNKNOWN;
+	private BluetoothState bluetoothState = BluetoothState.UNKNOWN;
 	private BroadcastReceiver bluetoothReceiver = null;
 
 	@Override
@@ -147,17 +96,20 @@ public abstract class KeyAgreementActivity extends BriarActivity implements
 		component.inject(this);
 	}
 
+	@SuppressWarnings("ConstantConditions")
 	@Override
 	public void onCreate(@Nullable Bundle state) {
 		super.onCreate(state);
 		setContentView(R.layout.activity_fragment_container_toolbar);
 		Toolbar toolbar = findViewById(R.id.toolbar);
 		setSupportActionBar(toolbar);
-		requireNonNull(getSupportActionBar()).setDisplayHomeAsUpEnabled(true);
+		getSupportActionBar().setDisplayHomeAsUpEnabled(true);
 		if (state == null) {
 			showInitialFragment(IntroFragment.newInstance());
 		}
-		IntentFilter filter = new IntentFilter(ACTION_SCAN_MODE_CHANGED);
+		IntentFilter filter = new IntentFilter();
+		filter.addAction(ACTION_STATE_CHANGED);
+		filter.addAction(ACTION_SCAN_MODE_CHANGED);
 		bluetoothReceiver = new BluetoothStateReceiver();
 		registerReceiver(bluetoothReceiver, filter);
 	}
@@ -170,17 +122,18 @@ public abstract class KeyAgreementActivity extends BriarActivity implements
 
 	@Override
 	public boolean onOptionsItemSelected(MenuItem item) {
-		if (item.getItemId() == android.R.id.home) {
+		switch (item.getItemId()) {
-			onBackPressed();
+			case android.R.id.home:
-			return true;
+				onBackPressed();
+				return true;
+			default:
+				return super.onOptionsItemSelected(item);
 		}
-		return super.onOptionsItemSelected(item);
 	}
 
 	@Override
 	public void onStart() {
 		super.onStart();
-		eventBus.addListener(this);
 		// Permissions may have been granted manually while we were stopped
 		cameraPermission = Permission.UNKNOWN;
 		locationPermission = Permission.UNKNOWN;
@@ -197,22 +150,11 @@ public abstract class KeyAgreementActivity extends BriarActivity implements
 
 	private void showQrCodeFragmentIfAllowed() {
 		if (isResumed && continueClicked && areEssentialPermissionsGranted()) {
-			if (isWifiReady() && isBluetoothReady()) {
+			if (bluetoothState == BluetoothState.UNKNOWN ||
-				LOG.info("Wifi and Bluetooth are ready");
+					bluetoothState == BluetoothState.ENABLED) {
+				requestBluetoothDiscoverable();
+			} else if (bluetoothState != BluetoothState.WAITING) {
 				showQrCodeFragment();
-			} else {
-				if (shouldEnableWifi()) {
-					LOG.info("Enabling wifi plugin");
-					hasEnabledWifi = true;
-					pluginManager.setPluginEnabled(LanTcpConstants.ID, true);
-				}
-				if (bluetoothDecision == BluetoothDecision.UNKNOWN) {
-					requestBluetoothDiscoverable();
-				} else if (shouldEnableBluetooth()) {
-					LOG.info("Enabling Bluetooth plugin");
-					hasEnabledBluetooth = true;
-					pluginManager.setPluginEnabled(BluetoothConstants.ID, true);
-				}
 			}
 		}
 	}
@@ -225,108 +167,57 @@ public abstract class KeyAgreementActivity extends BriarActivity implements
 						locationPermission == Permission.PERMANENTLY_DENIED);
 	}
 
-	private boolean isWifiReady() {
-		Plugin p = pluginManager.getPlugin(LanTcpConstants.ID);
-		if (p == null) return true; // Continue without wifi
-		State state = p.getState();
-		// Wait for plugin to become enabled
-		return state == ACTIVE || state == INACTIVE;
-	}
-
-	private boolean isBluetoothReady() {
-		if (bluetoothDecision == BluetoothDecision.UNKNOWN ||
-				bluetoothDecision == BluetoothDecision.WAITING) {
-			// Wait for decision
-			return false;
-		}
-		if (bluetoothDecision == BluetoothDecision.NO_ADAPTER
-				|| bluetoothDecision == BluetoothDecision.REFUSED) {
-			// Continue without Bluetooth
-			return true;
-		}
-		BluetoothAdapter bt = BluetoothAdapter.getDefaultAdapter();
-		if (bt == null) return true; // Continue without Bluetooth
-		if (bt.getScanMode() != SCAN_MODE_CONNECTABLE_DISCOVERABLE) {
-			// Wait for adapter to become discoverable
-			return false;
-		}
-		Plugin p = pluginManager.getPlugin(BluetoothConstants.ID);
-		if (p == null) return true; // Continue without Bluetooth
-		// Wait for plugin to become active
-		return p.getState() == ACTIVE;
-	}
-
-	private boolean shouldEnableWifi() {
-		if (hasEnabledWifi) return false;
-		Plugin p = pluginManager.getPlugin(LanTcpConstants.ID);
-		if (p == null) return false;
-		State state = p.getState();
-		return state == STARTING_STOPPING || state == DISABLED;
-	}
-
-	private void requestBluetoothDiscoverable() {
-		BluetoothAdapter bt = BluetoothAdapter.getDefaultAdapter();
-		if (bt == null) {
-			bluetoothDecision = BluetoothDecision.NO_ADAPTER;
-			showQrCodeFragmentIfAllowed();
-		} else {
-			Intent i = new Intent(ACTION_REQUEST_DISCOVERABLE);
-			if (i.resolveActivity(getPackageManager()) != null) {
-				LOG.info("Asking for Bluetooth discoverability");
-				bluetoothDecision = BluetoothDecision.WAITING;
-				wasAdapterEnabled = bt.isEnabled();
-				startActivityForResult(i, REQUEST_BLUETOOTH_DISCOVERABLE);
-			} else {
-				bluetoothDecision = BluetoothDecision.NO_ADAPTER;
-				showQrCodeFragmentIfAllowed();
-			}
-		}
-	}
-
-	private boolean shouldEnableBluetooth() {
-		if (bluetoothDecision != BluetoothDecision.ACCEPTED) return false;
-		if (hasEnabledBluetooth) return false;
-		Plugin p = pluginManager.getPlugin(BluetoothConstants.ID);
-		if (p == null) return false;
-		State state = p.getState();
-		return state == STARTING_STOPPING || state == DISABLED;
-	}
-
 	@Override
 	protected void onPause() {
 		super.onPause();
 		isResumed = false;
 	}
 
-	@Override
-	protected void onStop() {
-		super.onStop();
-		eventBus.removeListener(this);
-	}
-
 	@Override
 	public void showNextScreen() {
 		continueClicked = true;
 		if (checkPermissions()) showQrCodeFragmentIfAllowed();
 	}
 
+	private void requestBluetoothDiscoverable() {
+		BluetoothAdapter bt = BluetoothAdapter.getDefaultAdapter();
+		if (bt == null) {
+			setBluetoothState(BluetoothState.NO_ADAPTER);
+		} else {
+			Intent i = new Intent(ACTION_REQUEST_DISCOVERABLE);
+			if (i.resolveActivity(getPackageManager()) != null) {
+				setBluetoothState(BluetoothState.WAITING);
+				wasAdapterEnabled = bt.isEnabled();
+				startActivityForResult(i, REQUEST_BLUETOOTH_DISCOVERABLE);
+			} else {
+				setBluetoothState(BluetoothState.NO_ADAPTER);
+			}
+		}
+	}
+
+	private void setBluetoothState(BluetoothState bluetoothState) {
+		LOG.info("Setting Bluetooth state to " + bluetoothState);
+		this.bluetoothState = bluetoothState;
+		if (!wasAdapterEnabled && bluetoothState == BluetoothState.ENABLED) {
+			eventBus.broadcast(new BluetoothEnabledEvent());
+			wasAdapterEnabled = true;
+		}
+		showQrCodeFragmentIfAllowed();
+	}
+
 	@Override
-	public void onActivityResult(int request, int result,
+	public void onActivityResult(int request, int result, Intent data) {
-			@Nullable Intent data) {
 		if (request == REQUEST_BLUETOOTH_DISCOVERABLE) {
 			if (result == RESULT_CANCELED) {
-				LOG.info("Bluetooth discoverability was refused");
+				setBluetoothState(BluetoothState.REFUSED);
-				bluetoothDecision = BluetoothDecision.REFUSED;
 			} else {
-				LOG.info("Bluetooth discoverability was accepted");
+				// If Bluetooth is already discoverable, show the QR code -
-				bluetoothDecision = BluetoothDecision.ACCEPTED;
+				// otherwise wait for the state or scan mode to change
-				if (!wasAdapterEnabled) {
+				BluetoothAdapter bt = BluetoothAdapter.getDefaultAdapter();
-					LOG.info("Bluetooth adapter was enabled by us");
+				if (bt == null) throw new AssertionError();
-					eventBus.broadcast(new BluetoothEnabledEvent());
+				if (bt.getScanMode() == SCAN_MODE_CONNECTABLE_DISCOVERABLE)
-					wasAdapterEnabled = true;
+					setBluetoothState(BluetoothState.DISCOVERABLE);
-				}
 			}
-			showQrCodeFragmentIfAllowed();
 		} else super.onActivityResult(request, result, data);
 	}
 
@@ -336,12 +227,7 @@ public abstract class KeyAgreementActivity extends BriarActivity implements
 		continueClicked = false;
 		// If we return to the intro fragment, ask for Bluetooth
 		// discoverability again before showing the QR code fragment
-		bluetoothDecision = BluetoothDecision.UNKNOWN;
+		bluetoothState = BluetoothState.UNKNOWN;
-		// If we return to the intro fragment, we may need to enable wifi and
-		// Bluetooth again
-		hasEnabledWifi = false;
-		hasEnabledBluetooth = false;
-
 		// FIXME #824
 		FragmentManager fm = getSupportFragmentManager();
 		if (fm.findFragmentByTag(KeyAgreementFragment.TAG) == null) {
@@ -353,6 +239,12 @@ public abstract class KeyAgreementActivity extends BriarActivity implements
 		}
 	}
 
+	protected void showErrorFragment(@StringRes int errorResId) {
+		String errorMsg = getString(errorResId);
+		BaseFragment f = ContactExchangeErrorFragment.newInstance(errorMsg);
+		showNextFragment(f);
+	}
+
 	private boolean checkPermissions() {
 		if (areEssentialPermissionsGranted()) return true;
 		// If the camera permission has been permanently denied, ask the
@@ -443,30 +335,24 @@ public abstract class KeyAgreementActivity extends BriarActivity implements
 				permission);
 	}
 
-	@Override
-	public void eventOccurred(Event e) {
-		if (e instanceof TransportStateEvent) {
-			TransportStateEvent t = (TransportStateEvent) e;
-			if (t.getTransportId().equals(BluetoothConstants.ID)) {
-				if (LOG.isLoggable(INFO)) {
-					LOG.info("Bluetooth state changed to " + t.getState());
-				}
-				showQrCodeFragmentIfAllowed();
-			} else if (t.getTransportId().equals(LanTcpConstants.ID)) {
-				if (LOG.isLoggable(INFO)) {
-					LOG.info("Wifi state changed to " + t.getState());
-				}
-				showQrCodeFragmentIfAllowed();
-			}
-		}
-	}
-
 	private class BluetoothStateReceiver extends BroadcastReceiver {
 
 		@Override
 		public void onReceive(Context context, Intent intent) {
-			LOG.info("Bluetooth scan mode changed");
+			String action = intent.getAction();
-			showQrCodeFragmentIfAllowed();
+			if (ACTION_STATE_CHANGED.equals(action)) {
+				int state = intent.getIntExtra(EXTRA_STATE, 0);
+				if (state == STATE_ON)
+					setBluetoothState(BluetoothState.ENABLED);
+				else setBluetoothState(BluetoothState.UNKNOWN);
+			} else if (ACTION_SCAN_MODE_CHANGED.equals(action)) {
+				int scanMode = intent.getIntExtra(EXTRA_SCAN_MODE, 0);
+				if (scanMode == SCAN_MODE_CONNECTABLE_DISCOVERABLE)
+					setBluetoothState(BluetoothState.DISCOVERABLE);
+				else if (scanMode == SCAN_MODE_CONNECTABLE)
+					setBluetoothState(BluetoothState.ENABLED);
+				else setBluetoothState(BluetoothState.UNKNOWN);
+			}
 		}
 	}
 }

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

@@ -15,27 +15,33 @@ import android.widget.Toast;
 
 import com.google.android.material.textfield.TextInputLayout;
 
+import org.briarproject.bramble.api.crypto.DecryptionResult;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.activity.ActivityComponent;
 import org.briarproject.briar.android.activity.BriarActivity;
-import org.briarproject.briar.android.controller.handler.UiResultHandler;
-import org.briarproject.briar.android.util.UiUtils;
 
 import javax.inject.Inject;
 
-import androidx.annotation.NonNull;
+import androidx.annotation.VisibleForTesting;
+import androidx.lifecycle.ViewModelProvider;
+import androidx.lifecycle.ViewModelProviders;
 
 import static android.view.View.INVISIBLE;
 import static android.view.View.VISIBLE;
+import static android.widget.Toast.LENGTH_LONG;
+import static org.briarproject.bramble.api.crypto.DecryptionResult.KEY_STRENGTHENER_ERROR;
+import static org.briarproject.bramble.api.crypto.DecryptionResult.SUCCESS;
 import static org.briarproject.bramble.api.crypto.PasswordStrengthEstimator.QUITE_WEAK;
+import static org.briarproject.briar.android.login.LoginUtils.createKeyStrengthenerErrorDialog;
 import static org.briarproject.briar.android.util.UiUtils.hideSoftKeyboard;
+import static org.briarproject.briar.android.util.UiUtils.setError;
 import static org.briarproject.briar.android.util.UiUtils.showSoftKeyboard;
 
 public class ChangePasswordActivity extends BriarActivity
 		implements OnClickListener, OnEditorActionListener {
 
 	@Inject
-	protected ChangePasswordController passwordController;
+	ViewModelProvider.Factory viewModelFactory;
 
 	private TextInputLayout currentPasswordEntryWrapper;
 	private TextInputLayout newPasswordEntryWrapper;
@@ -47,11 +53,17 @@ public class ChangePasswordActivity extends BriarActivity
 	private Button changePasswordButton;
 	private ProgressBar progress;
 
+	@VisibleForTesting
+	ChangePasswordViewModel viewModel;
+
 	@Override
 	public void onCreate(Bundle state) {
 		super.onCreate(state);
 		setContentView(R.layout.activity_change_password);
 
+		viewModel = ViewModelProviders.of(this, viewModelFactory)
+				.get(ChangePasswordViewModel.class);
+
 		currentPasswordEntryWrapper =
 				findViewById(R.id.current_password_entry_wrapper);
 		newPasswordEntryWrapper = findViewById(R.id.new_password_entry_wrapper);
@@ -102,13 +114,12 @@ public class ChangePasswordActivity extends BriarActivity
 		String firstPassword = newPassword.getText().toString();
 		String secondPassword = newPasswordConfirmation.getText().toString();
 		boolean passwordsMatch = firstPassword.equals(secondPassword);
-		float strength =
+		float strength = viewModel.estimatePasswordStrength(firstPassword);
-				passwordController.estimatePasswordStrength(firstPassword);
 		strengthMeter.setStrength(strength);
-		UiUtils.setError(newPasswordEntryWrapper,
+		setError(newPasswordEntryWrapper,
 				getString(R.string.password_too_weak),
 				firstPassword.length() > 0 && strength < QUITE_WEAK);
-		UiUtils.setError(newPasswordConfirmationWrapper,
+		setError(newPasswordConfirmationWrapper,
 				getString(R.string.passwords_do_not_match),
 				secondPassword.length() > 0 && !passwordsMatch);
 		changePasswordButton.setEnabled(
@@ -127,32 +138,34 @@ public class ChangePasswordActivity extends BriarActivity
 		// Replace the button with a progress bar
 		changePasswordButton.setVisibility(INVISIBLE);
 		progress.setVisibility(VISIBLE);
-		passwordController.changePassword(currentPassword.getText().toString(),
+
-				newPassword.getText().toString(),
+		String curPwd = currentPassword.getText().toString();
-				new UiResultHandler<Boolean>(this) {
+		String newPwd = newPassword.getText().toString();
-					@Override
+		viewModel.changePassword(curPwd, newPwd).observeEvent(this, result -> {
-					public void onResultUi(@NonNull Boolean result) {
+					if (result == SUCCESS) {
-						if (result) {
+						Toast.makeText(ChangePasswordActivity.this,
-							Toast.makeText(ChangePasswordActivity.this,
+								R.string.password_changed,
-									R.string.password_changed,
+								LENGTH_LONG).show();
-									Toast.LENGTH_LONG).show();
+						setResult(RESULT_OK);
-							setResult(RESULT_OK);
+						supportFinishAfterTransition();
-							supportFinishAfterTransition();
+					} else {
-						} else {
+						tryAgain(result);
-							tryAgain();
-						}
 					}
-				});
+				}
+		);
 	}
 
-	private void tryAgain() {
+	private void tryAgain(DecryptionResult result) {
-		UiUtils.setError(currentPasswordEntryWrapper,
-				getString(R.string.try_again), true);
 		changePasswordButton.setVisibility(VISIBLE);
 		progress.setVisibility(INVISIBLE);
-		currentPassword.setText("");
+		if (result == KEY_STRENGTHENER_ERROR) {
-
+			createKeyStrengthenerErrorDialog(this).show();
-		// show the keyboard again
+		} else {
-		showSoftKeyboard(currentPassword);
+			setError(currentPasswordEntryWrapper,
+					getString(R.string.try_again), true);
+			currentPassword.setText("");
+			// show the keyboard again
+			showSoftKeyboard(currentPassword);
+		}
 	}
 }

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

@@ -1,43 +0,0 @@
-package org.briarproject.briar.android.login;
-
-import org.briarproject.bramble.api.account.AccountManager;
-import org.briarproject.bramble.api.crypto.PasswordStrengthEstimator;
-import org.briarproject.bramble.api.lifecycle.IoExecutor;
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.briar.android.controller.handler.ResultHandler;
-
-import java.util.concurrent.Executor;
-
-import javax.inject.Inject;
-
-@NotNullByDefault
-public class ChangePasswordControllerImpl implements ChangePasswordController {
-
-	protected final AccountManager accountManager;
-	protected final Executor ioExecutor;
-	private final PasswordStrengthEstimator strengthEstimator;
-
-	@Inject
-	ChangePasswordControllerImpl(AccountManager accountManager,
-			@IoExecutor Executor ioExecutor,
-			PasswordStrengthEstimator strengthEstimator) {
-		this.accountManager = accountManager;
-		this.ioExecutor = ioExecutor;
-		this.strengthEstimator = strengthEstimator;
-	}
-
-	@Override
-	public float estimatePasswordStrength(String password) {
-		return strengthEstimator.estimateStrength(password);
-	}
-
-	@Override
-	public void changePassword(String oldPassword, String newPassword,
-			ResultHandler<Boolean> resultHandler) {
-		ioExecutor.execute(() -> {
-			boolean changed =
-					accountManager.changePassword(oldPassword, newPassword);
-			resultHandler.onResult(changed);
-		});
-	}
-}

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

@@ -0,0 +1,53 @@
+package org.briarproject.briar.android.login;
+
+import org.briarproject.bramble.api.account.AccountManager;
+import org.briarproject.bramble.api.crypto.DecryptionException;
+import org.briarproject.bramble.api.crypto.DecryptionResult;
+import org.briarproject.bramble.api.crypto.PasswordStrengthEstimator;
+import org.briarproject.bramble.api.lifecycle.IoExecutor;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.briar.android.viewmodel.LiveEvent;
+import org.briarproject.briar.android.viewmodel.MutableLiveEvent;
+
+import java.util.concurrent.Executor;
+
+import javax.inject.Inject;
+
+import androidx.lifecycle.ViewModel;
+
+import static org.briarproject.bramble.api.crypto.DecryptionResult.SUCCESS;
+
+@NotNullByDefault
+public class ChangePasswordViewModel extends ViewModel {
+
+	private final AccountManager accountManager;
+	private final Executor ioExecutor;
+	private final PasswordStrengthEstimator strengthEstimator;
+
+	@Inject
+	ChangePasswordViewModel(AccountManager accountManager,
+			@IoExecutor Executor ioExecutor,
+			PasswordStrengthEstimator strengthEstimator) {
+		this.accountManager = accountManager;
+		this.ioExecutor = ioExecutor;
+		this.strengthEstimator = strengthEstimator;
+	}
+
+	float estimatePasswordStrength(String password) {
+		return strengthEstimator.estimateStrength(password);
+	}
+
+	LiveEvent<DecryptionResult> changePassword(String oldPassword,
+			String newPassword) {
+		MutableLiveEvent<DecryptionResult> result = new MutableLiveEvent<>();
+		ioExecutor.execute(() -> {
+			try {
+				accountManager.changePassword(oldPassword, newPassword);
+				result.postEvent(SUCCESS);
+			} catch (DecryptionException e) {
+				result.postEvent(e.getDecryptionResult());
+			}
+		});
+		return result;
+	}
+}

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

@@ -0,0 +1,23 @@
+package org.briarproject.briar.android.login;
+
+import org.briarproject.briar.android.viewmodel.ViewModelKey;
+
+import androidx.lifecycle.ViewModel;
+import dagger.Binds;
+import dagger.Module;
+import dagger.multibindings.IntoMap;
+
+@Module
+public abstract class LoginModule {
+
+	@Binds
+	@IntoMap
+	@ViewModelKey(StartupViewModel.class)
+	abstract ViewModel bindStartupViewModel(StartupViewModel viewModel);
+
+	@Binds
+	@IntoMap
+	@ViewModelKey(ChangePasswordViewModel.class)
+	abstract ViewModel bindChangePasswordViewModel(
+			ChangePasswordViewModel viewModel);
+}

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

@@ -0,0 +1,30 @@
+package org.briarproject.briar.android.login;
+
+import android.content.Context;
+import android.graphics.drawable.Drawable;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.briar.R;
+
+import androidx.appcompat.app.AlertDialog;
+
+import static androidx.core.content.ContextCompat.getColor;
+import static androidx.core.content.ContextCompat.getDrawable;
+import static androidx.core.graphics.drawable.DrawableCompat.setTint;
+import static java.util.Objects.requireNonNull;
+
+@NotNullByDefault
+class LoginUtils {
+
+	static AlertDialog createKeyStrengthenerErrorDialog(Context ctx) {
+		AlertDialog.Builder builder =
+				new AlertDialog.Builder(ctx, R.style.BriarDialogTheme);
+		Drawable icon = getDrawable(ctx, R.drawable.alerts_and_states_error);
+		setTint(requireNonNull(icon), getColor(ctx, R.color.color_primary));
+		builder.setIcon(icon);
+		builder.setTitle(R.string.dialog_title_cannot_check_password);
+		builder.setMessage(R.string.dialog_message_cannot_check_password);
+		builder.setPositiveButton(R.string.ok, null);
+		return builder.create();
+	}
+}

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

@@ -12,6 +12,7 @@ import android.widget.ProgressBar;
 import com.google.android.material.textfield.TextInputEditText;
 import com.google.android.material.textfield.TextInputLayout;
 
+import org.briarproject.bramble.api.crypto.DecryptionResult;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.briar.R;
@@ -28,6 +29,9 @@ import androidx.lifecycle.ViewModelProviders;
 import static android.view.View.INVISIBLE;
 import static android.view.View.VISIBLE;
 import static android.view.inputmethod.EditorInfo.IME_ACTION_DONE;
+import static org.briarproject.bramble.api.crypto.DecryptionResult.KEY_STRENGTHENER_ERROR;
+import static org.briarproject.bramble.api.crypto.DecryptionResult.SUCCESS;
+import static org.briarproject.briar.android.login.LoginUtils.createKeyStrengthenerErrorDialog;
 import static org.briarproject.briar.android.util.UiUtils.enterPressed;
 import static org.briarproject.briar.android.util.UiUtils.hideSoftKeyboard;
 import static org.briarproject.briar.android.util.UiUtils.setError;
@@ -58,12 +62,13 @@ public class PasswordFragment extends BaseFragment implements TextWatcher {
 			@Nullable ViewGroup container,
 			@Nullable Bundle savedInstanceState) {
 		View v = inflater.inflate(R.layout.fragment_password, container,
-						false);
+				false);
 
 		viewModel = ViewModelProviders.of(requireActivity(), viewModelFactory)
 				.get(StartupViewModel.class);
-		viewModel.getPasswordValidated().observeEvent(this, valid -> {
+
-			if (!valid) onPasswordInvalid();
+		viewModel.getPasswordValidated().observeEvent(this, result -> {
+			if (result != SUCCESS) onPasswordInvalid(result);
 		});
 
 		signInButton = v.findViewById(R.id.btn_sign_in);
@@ -107,18 +112,20 @@ public class PasswordFragment extends BaseFragment implements TextWatcher {
 		viewModel.validatePassword(password.getText().toString());
 	}
 
-	private void onPasswordInvalid() {
+	private void onPasswordInvalid(DecryptionResult result) {
-		setError(input, getString(R.string.try_again), true);
 		signInButton.setVisibility(VISIBLE);
 		progress.setVisibility(INVISIBLE);
-		password.setText(null);
+		if (result == KEY_STRENGTHENER_ERROR) {
-
+			createKeyStrengthenerErrorDialog(requireContext()).show();
-		// show the keyboard again
+		} else {
-		showSoftKeyboard(password);
+			setError(input, getString(R.string.try_again), true);
+			password.setText(null);
+			// show the keyboard again
+			showSoftKeyboard(password);
+		}
 	}
 
-	public void onForgottenPasswordClick() {
+	private void onForgottenPasswordClick() {
-		// TODO Encapsulate the dialog in a re-usable fragment
 		AlertDialog.Builder builder = new AlertDialog.Builder(requireContext(),
 				R.style.BriarDialogTheme);
 		builder.setTitle(R.string.dialog_title_lost_password);

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

@@ -3,6 +3,8 @@ package org.briarproject.briar.android.login;
 import android.app.Application;
 
 import org.briarproject.bramble.api.account.AccountManager;
+import org.briarproject.bramble.api.crypto.DecryptionException;
+import org.briarproject.bramble.api.crypto.DecryptionResult;
 import org.briarproject.bramble.api.event.Event;
 import org.briarproject.bramble.api.event.EventBus;
 import org.briarproject.bramble.api.event.EventListener;
@@ -24,6 +26,7 @@ import androidx.lifecycle.AndroidViewModel;
 import androidx.lifecycle.LiveData;
 import androidx.lifecycle.MutableLiveData;
 
+import static org.briarproject.bramble.api.crypto.DecryptionResult.SUCCESS;
 import static org.briarproject.bramble.api.lifecycle.LifecycleManager.LifecycleState.COMPACTING_DATABASE;
 import static org.briarproject.bramble.api.lifecycle.LifecycleManager.LifecycleState.MIGRATING_DATABASE;
 import static org.briarproject.bramble.api.lifecycle.LifecycleManager.LifecycleState.STARTING_SERVICES;
@@ -46,7 +49,7 @@ public class StartupViewModel extends AndroidViewModel
 	@IoExecutor
 	private final Executor ioExecutor;
 
-	private final MutableLiveEvent<Boolean> passwordValidated =
+	private final MutableLiveEvent<DecryptionResult> passwordValidated =
 			new MutableLiveEvent<>();
 	private final MutableLiveEvent<Boolean> accountDeleted =
 			new MutableLiveEvent<>();
@@ -105,13 +108,17 @@ public class StartupViewModel extends AndroidViewModel
 
 	void validatePassword(String password) {
 		ioExecutor.execute(() -> {
-			boolean signedIn = accountManager.signIn(password);
+			try {
-			passwordValidated.postEvent(signedIn);
+				accountManager.signIn(password);
-			if (signedIn) state.postValue(SIGNED_IN);
+				passwordValidated.postEvent(SUCCESS);
+				state.postValue(SIGNED_IN);
+			} catch (DecryptionException e) {
+				passwordValidated.postEvent(e.getDecryptionResult());
+			}
 		});
 	}
 
-	LiveEvent<Boolean> getPasswordValidated() {
+	LiveEvent<DecryptionResult> getPasswordValidated() {
 		return passwordValidated;
 	}
 

briar-android/src/main/java/org/briarproject/briar/android/navdrawer/NavDrawerActivity.java

@@ -1,12 +1,16 @@
 package org.briarproject.briar.android.navdrawer;
 
+import android.annotation.SuppressLint;
 import android.content.Intent;
 import android.content.res.Configuration;
 import android.net.Uri;
 import android.os.Bundle;
+import android.view.LayoutInflater;
 import android.view.MenuItem;
 import android.view.View;
 import android.view.ViewGroup;
+import android.widget.BaseAdapter;
+import android.widget.GridView;
 import android.widget.ImageView;
 import android.widget.TextView;
 
@@ -17,11 +21,16 @@ import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.lifecycle.LifecycleManager;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
+import org.briarproject.bramble.api.plugin.BluetoothConstants;
+import org.briarproject.bramble.api.plugin.LanTcpConstants;
+import org.briarproject.bramble.api.plugin.TorConstants;
+import org.briarproject.bramble.api.plugin.TransportId;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.activity.ActivityComponent;
 import org.briarproject.briar.android.activity.BriarActivity;
 import org.briarproject.briar.android.blog.FeedFragment;
 import org.briarproject.briar.android.contact.ContactListFragment;
+import org.briarproject.briar.android.controller.handler.UiResultHandler;
 import org.briarproject.briar.android.forum.ForumListFragment;
 import org.briarproject.briar.android.fragment.BaseFragment;
 import org.briarproject.briar.android.fragment.BaseFragment.BaseFragmentListener;
@@ -29,21 +38,23 @@ import org.briarproject.briar.android.logout.SignOutFragment;
 import org.briarproject.briar.android.privategroup.list.GroupListFragment;
 import org.briarproject.briar.android.settings.SettingsActivity;
 
+import java.util.ArrayList;
+import java.util.List;
 import java.util.logging.Logger;
 
 import javax.inject.Inject;
 
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
+import androidx.annotation.UiThread;
 import androidx.appcompat.app.ActionBar;
 import androidx.appcompat.app.ActionBarDrawerToggle;
 import androidx.appcompat.widget.Toolbar;
 import androidx.core.app.ActivityCompat;
+import androidx.core.content.ContextCompat;
 import androidx.drawerlayout.widget.DrawerLayout;
 import androidx.fragment.app.FragmentManager;
 import androidx.fragment.app.FragmentTransaction;
-import androidx.lifecycle.ViewModelProvider;
-import androidx.lifecycle.ViewModelProviders;
 
 import static android.view.View.GONE;
 import static android.view.View.VISIBLE;
@@ -61,7 +72,8 @@ import static org.briarproject.briar.android.util.UiUtils.getDaysUntilExpiry;
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
 public class NavDrawerActivity extends BriarActivity implements
-		BaseFragmentListener, OnNavigationItemSelectedListener {
+		BaseFragmentListener, TransportStateListener,
+		OnNavigationItemSelectedListener {
 
 	private static final Logger LOG =
 			getLogger(NavDrawerActivity.class.getName());
@@ -79,18 +91,19 @@ public class NavDrawerActivity extends BriarActivity implements
 	public static Uri SIGN_OUT_URI =
 			Uri.parse("briar-content://org.briarproject.briar/sign-out");
 
-	private NavDrawerViewModel viewModel;
 	private ActionBarDrawerToggle drawerToggle;
 
 	@Inject
-	ViewModelProvider.Factory viewModelFactory;
+	NavDrawerController controller;
-
 	@Inject
 	LifecycleManager lifecycleManager;
 
 	private DrawerLayout drawerLayout;
 	private NavigationView navigation;
 
+	private List<Transport> transports;
+	private BaseAdapter transportsAdapter;
+
 	@Override
 	public void injectActivity(ActivityComponent component) {
 		component.inject(this);
@@ -102,20 +115,10 @@ public class NavDrawerActivity extends BriarActivity implements
 		exitIfStartupFailed(getIntent());
 		setContentView(R.layout.activity_nav_drawer);
 
-		viewModel = ViewModelProviders.of(this, viewModelFactory)
-				.get(NavDrawerViewModel.class);
-
-		viewModel.showExpiryWarning().observe(this, this::showExpiryWarning);
-		viewModel.shouldAskForDozeWhitelisting().observe(this, ask -> {
-			if (ask) showDozeDialog(getString(R.string.setup_doze_intro));
-		});
-
-		View drawerScrollView = findViewById(R.id.drawerScrollView);
-		new PluginViewController(drawerScrollView, this, viewModel);
-
 		Toolbar toolbar = findViewById(R.id.toolbar);
 		drawerLayout = findViewById(R.id.drawer_layout);
 		navigation = findViewById(R.id.navigation);
+		GridView transportsView = findViewById(R.id.transportsView);
 
 		setSupportActionBar(toolbar);
 		ActionBar actionBar = requireNonNull(getSupportActionBar());
@@ -128,6 +131,9 @@ public class NavDrawerActivity extends BriarActivity implements
 		drawerLayout.addDrawerListener(drawerToggle);
 		navigation.setNavigationItemSelectedListener(this);
 
+		initializeTransports(getLayoutInflater());
+		transportsView.setAdapter(transportsAdapter);
+
 		lockManager.isLockable().observe(this, this::setLockVisible);
 
 		if (lifecycleManager.getLifecycleState().isAfter(RUNNING)) {
@@ -143,10 +149,17 @@ public class NavDrawerActivity extends BriarActivity implements
 	}
 
 	@Override
+	@SuppressLint("NewApi")
 	public void onStart() {
 		super.onStart();
+		updateTransports();
 		lockManager.checkIfLockable();
-		viewModel.checkExpiryWarning();
+		controller.showExpiryWarning(new UiResultHandler<Boolean>(this) {
+			@Override
+			public void onResultUi(Boolean expiry) {
+				if (expiry) showExpiryWarning();
+			}
+		});
 	}
 
 	@Override
@@ -154,7 +167,16 @@ public class NavDrawerActivity extends BriarActivity implements
 			@Nullable Intent data) {
 		super.onActivityResult(request, result, data);
 		if (request == REQUEST_PASSWORD && result == RESULT_OK) {
-			viewModel.checkDozeWhitelisting();
+			controller.shouldAskForDozeWhitelisting(this,
+					new UiResultHandler<Boolean>(this) {
+						@Override
+						public void onResultUi(Boolean ask) {
+							if (ask) {
+								showDozeDialog(
+										getString(R.string.setup_doze_intro));
+							}
+						}
+					});
 		}
 	}
 
@@ -324,30 +346,134 @@ public class NavDrawerActivity extends BriarActivity implements
 		if (item != null) item.setVisible(visible);
 	}
 
-	private void showExpiryWarning(boolean show) {
+	private void showExpiryWarning() {
 		int daysUntilExpiry = getDaysUntilExpiry();
-		if (daysUntilExpiry < 0) {
+		if (daysUntilExpiry < 0) signOut();
-			signOut();
-			return;
-		}
 
+		// show expiry warning text
 		ViewGroup expiryWarning = findViewById(R.id.expiryWarning);
-		if (show) {
+		TextView expiryWarningText =
-			// show expiry warning text
+				expiryWarning.findViewById(R.id.expiryWarningText);
-			TextView expiryWarningText =
+		// make close button functional
-					expiryWarning.findViewById(R.id.expiryWarningText);
+		ImageView expiryWarningClose =
-			String text = getResources().getQuantityString(
+				expiryWarning.findViewById(R.id.expiryWarningClose);
-					R.plurals.expiry_warning, daysUntilExpiry, daysUntilExpiry);
+
-			expiryWarningText.setText(text);
+		expiryWarningText.setText(getResources()
-			// make close button functional
+				.getQuantityString(R.plurals.expiry_warning,
-			ImageView expiryWarningClose =
+						daysUntilExpiry, daysUntilExpiry));
-					expiryWarning.findViewById(R.id.expiryWarningClose);
+
-			expiryWarningClose.setOnClickListener(v ->
+		expiryWarningClose.setOnClickListener(v -> {
-					viewModel.expiryWarningDismissed()
+			controller.expiryWarningDismissed();
-			);
-			expiryWarning.setVisibility(VISIBLE);
-		} else {
 			expiryWarning.setVisibility(GONE);
+		});
+
+		expiryWarning.setVisibility(VISIBLE);
+	}
+
+	private void initializeTransports(LayoutInflater inflater) {
+		transports = new ArrayList<>(3);
+
+		Transport tor = new Transport();
+		tor.id = TorConstants.ID;
+		tor.enabled = controller.isTransportRunning(tor.id);
+		tor.iconId = R.drawable.transport_tor;
+		tor.textId = R.string.transport_tor;
+		transports.add(tor);
+
+		Transport bt = new Transport();
+		bt.id = BluetoothConstants.ID;
+		bt.enabled = controller.isTransportRunning(bt.id);
+		bt.iconId = R.drawable.transport_bt;
+		bt.textId = R.string.transport_bt;
+		transports.add(bt);
+
+		Transport lan = new Transport();
+		lan.id = LanTcpConstants.ID;
+		lan.enabled = controller.isTransportRunning(lan.id);
+		lan.iconId = R.drawable.transport_lan;
+		lan.textId = R.string.transport_lan;
+		transports.add(lan);
+
+		transportsAdapter = new BaseAdapter() {
+			@Override
+			public int getCount() {
+				return transports.size();
+			}
+
+			@Override
+			public Transport getItem(int position) {
+				return transports.get(position);
+			}
+
+			@Override
+			public long getItemId(int position) {
+				return 0;
+			}
+
+			@Override
+			public View getView(int position, View convertView,
+					ViewGroup parent) {
+				View view;
+				if (convertView != null) {
+					view = convertView;
+				} else {
+					view = inflater.inflate(R.layout.list_item_transport,
+							parent, false);
+				}
+
+				Transport t = getItem(position);
+				int c;
+				if (t.enabled) {
+					c = ContextCompat.getColor(NavDrawerActivity.this,
+							R.color.briar_green_light);
+				} else {
+					c = ContextCompat.getColor(NavDrawerActivity.this,
+							android.R.color.tertiary_text_light);
+				}
+
+				ImageView icon = view.findViewById(R.id.imageView);
+				icon.setImageDrawable(ContextCompat
+						.getDrawable(NavDrawerActivity.this, t.iconId));
+				icon.setColorFilter(c);
+
+				TextView text = view.findViewById(R.id.textView);
+				text.setText(getString(t.textId));
+
+				return view;
+			}
+		};
+	}
+
+	@UiThread
+	private void setTransport(TransportId id, boolean enabled) {
+		if (transports == null || transportsAdapter == null) return;
+		for (Transport t : transports) {
+			if (t.id.equals(id)) {
+				t.enabled = enabled;
+				transportsAdapter.notifyDataSetChanged();
+				break;
+			}
 		}
 	}
+
+	private void updateTransports() {
+		if (transports == null || transportsAdapter == null) return;
+		for (Transport t : transports) {
+			t.enabled = controller.isTransportRunning(t.id);
+		}
+		transportsAdapter.notifyDataSetChanged();
+	}
+
+	@Override
+	public void stateUpdate(TransportId id, boolean enabled) {
+		setTransport(id, enabled);
+	}
+
+	private static class Transport {
+
+		private TransportId id;
+		private boolean enabled;
+		private int iconId;
+		private int textId;
+	}
 }

briar-android/src/main/java/org/briarproject/briar/android/navdrawer/NavDrawerController.java

@@ -0,0 +1,22 @@
+package org.briarproject.briar.android.navdrawer;
+
+import android.content.Context;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.plugin.TransportId;
+import org.briarproject.briar.android.controller.ActivityLifecycleController;
+import org.briarproject.briar.android.controller.handler.ResultHandler;
+
+@NotNullByDefault
+public interface NavDrawerController extends ActivityLifecycleController {
+
+	boolean isTransportRunning(TransportId transportId);
+
+	void showExpiryWarning(ResultHandler<Boolean> handler);
+
+	void expiryWarningDismissed();
+
+	void shouldAskForDozeWhitelisting(Context ctx,
+			ResultHandler<Boolean> handler);
+
+}

briar-android/src/main/java/org/briarproject/briar/android/navdrawer/NavDrawerControllerImpl.java

@@ -0,0 +1,182 @@
+package org.briarproject.briar.android.navdrawer;
+
+import android.app.Activity;
+import android.content.Context;
+
+import org.briarproject.bramble.api.db.DatabaseExecutor;
+import org.briarproject.bramble.api.db.DbException;
+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.LifecycleManager;
+import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
+import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
+import org.briarproject.bramble.api.plugin.Plugin;
+import org.briarproject.bramble.api.plugin.PluginManager;
+import org.briarproject.bramble.api.plugin.TransportId;
+import org.briarproject.bramble.api.plugin.event.TransportDisabledEvent;
+import org.briarproject.bramble.api.plugin.event.TransportEnabledEvent;
+import org.briarproject.bramble.api.settings.Settings;
+import org.briarproject.bramble.api.settings.SettingsManager;
+import org.briarproject.briar.android.controller.DbControllerImpl;
+import org.briarproject.briar.android.controller.handler.ResultHandler;
+
+import java.util.concurrent.Executor;
+import java.util.logging.Logger;
+
+import javax.inject.Inject;
+
+import static java.util.concurrent.TimeUnit.DAYS;
+import static java.util.logging.Level.INFO;
+import static java.util.logging.Level.WARNING;
+import static java.util.logging.Logger.getLogger;
+import static org.briarproject.bramble.util.LogUtils.logException;
+import static org.briarproject.briar.android.TestingConstants.EXPIRY_DATE;
+import static org.briarproject.briar.android.TestingConstants.IS_DEBUG_BUILD;
+import static org.briarproject.briar.android.controller.BriarControllerImpl.DOZE_ASK_AGAIN;
+import static org.briarproject.briar.android.settings.SettingsFragment.SETTINGS_NAMESPACE;
+import static org.briarproject.briar.android.util.UiUtils.needsDozeWhitelisting;
+
+@MethodsNotNullByDefault
+@ParametersNotNullByDefault
+public class NavDrawerControllerImpl extends DbControllerImpl
+		implements NavDrawerController, EventListener {
+
+	private static final Logger LOG =
+			getLogger(NavDrawerControllerImpl.class.getName());
+
+	private static final String EXPIRY_DATE_WARNING = "expiryDateWarning";
+
+	private final PluginManager pluginManager;
+	private final SettingsManager settingsManager;
+	private final EventBus eventBus;
+
+	// UI thread
+	private TransportStateListener listener;
+
+	@Inject
+	NavDrawerControllerImpl(@DatabaseExecutor Executor dbExecutor,
+			LifecycleManager lifecycleManager, PluginManager pluginManager,
+			SettingsManager settingsManager, EventBus eventBus) {
+		super(dbExecutor, lifecycleManager);
+		this.pluginManager = pluginManager;
+		this.settingsManager = settingsManager;
+		this.eventBus = eventBus;
+	}
+
+	@Override
+	public void onActivityCreate(Activity activity) {
+		listener = (TransportStateListener) activity;
+	}
+
+	@Override
+	public void onActivityStart() {
+		eventBus.addListener(this);
+	}
+
+	@Override
+	public void onActivityStop() {
+		eventBus.removeListener(this);
+	}
+
+	@Override
+	public void onActivityDestroy() {
+	}
+
+	@Override
+	public void eventOccurred(Event e) {
+		if (e instanceof TransportEnabledEvent) {
+			TransportId id = ((TransportEnabledEvent) e).getTransportId();
+			if (LOG.isLoggable(INFO)) {
+				LOG.info("TransportEnabledEvent: " + id.getString());
+			}
+			listener.stateUpdate(id, true);
+		} else if (e instanceof TransportDisabledEvent) {
+			TransportId id = ((TransportDisabledEvent) e).getTransportId();
+			if (LOG.isLoggable(INFO)) {
+				LOG.info("TransportDisabledEvent: " + id.getString());
+			}
+			listener.stateUpdate(id, false);
+		}
+	}
+
+	@Override
+	public void showExpiryWarning(ResultHandler<Boolean> handler) {
+		if (!IS_DEBUG_BUILD) {
+			handler.onResult(false);
+			return;
+		}
+		runOnDbThread(() -> {
+			try {
+				Settings settings =
+						settingsManager.getSettings(SETTINGS_NAMESPACE);
+				int warningInt = settings.getInt(EXPIRY_DATE_WARNING, 0);
+
+				if (warningInt == 0) {
+					// we have not warned before
+					handler.onResult(true);
+				} else {
+					long warningLong = warningInt * 1000L;
+					long now = System.currentTimeMillis();
+					long daysSinceLastWarning =
+							(now - warningLong) / DAYS.toMillis(1);
+					long daysBeforeExpiry =
+							(EXPIRY_DATE - now) / DAYS.toMillis(1);
+
+					if (daysSinceLastWarning >= 30) {
+						handler.onResult(true);
+					} else if (daysBeforeExpiry <= 3 &&
+							daysSinceLastWarning > 0) {
+						handler.onResult(true);
+					} else {
+						handler.onResult(false);
+					}
+				}
+			} catch (DbException e) {
+				logException(LOG, WARNING, e);
+			}
+		});
+	}
+
+	@Override
+	public void expiryWarningDismissed() {
+		runOnDbThread(() -> {
+			try {
+				Settings settings = new Settings();
+				int date = (int) (System.currentTimeMillis() / 1000L);
+				settings.putInt(EXPIRY_DATE_WARNING, date);
+				settingsManager.mergeSettings(settings, SETTINGS_NAMESPACE);
+			} catch (DbException e) {
+				logException(LOG, WARNING, e);
+			}
+		});
+	}
+
+	@Override
+	public void shouldAskForDozeWhitelisting(Context ctx,
+			ResultHandler<Boolean> handler) {
+		// check this first, to hit the DbThread only when really necessary
+		if (!needsDozeWhitelisting(ctx)) {
+			handler.onResult(false);
+			return;
+		}
+		runOnDbThread(() -> {
+			try {
+				Settings settings =
+						settingsManager.getSettings(SETTINGS_NAMESPACE);
+				boolean ask = settings.getBoolean(DOZE_ASK_AGAIN, true);
+				handler.onResult(ask);
+			} catch (DbException e) {
+				logException(LOG, WARNING, e);
+				handler.onResult(true);
+			}
+		});
+	}
+
+	@Override
+	public boolean isTransportRunning(TransportId transportId) {
+		Plugin plugin = pluginManager.getPlugin(transportId);
+		return plugin != null && plugin.isRunning();
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/navdrawer/NavDrawerModule.java

@@ -1,19 +0,0 @@
-package org.briarproject.briar.android.navdrawer;
-
-import org.briarproject.briar.android.viewmodel.ViewModelKey;
-
-import androidx.lifecycle.ViewModel;
-import dagger.Binds;
-import dagger.Module;
-import dagger.multibindings.IntoMap;
-
-@Module
-public abstract class NavDrawerModule {
-
-	@Binds
-	@IntoMap
-	@ViewModelKey(NavDrawerViewModel.class)
-	abstract ViewModel bindNavDrawerViewModel(
-			NavDrawerViewModel navDrawerViewModel);
-
-}