DO NOT MERGE: Add hacky poller method for testing discovery.

Discovery finishes quickly on some devices if called at the wrong time.

bramble-android/build.gradle

@@ -11,8 +11,8 @@ android {
 	defaultConfig {
 		minSdkVersion 16
 		targetSdkVersion 28
-		versionCode 10205
-		versionName "1.2.5"
+		versionCode 10207
+		versionName "1.2.7"
 		consumerProguardFiles 'proguard-rules.txt'
 
 		testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"

bramble-android/src/main/java/org/briarproject/bramble/account/AndroidAccountManager.java

@@ -12,6 +12,7 @@ import org.briarproject.bramble.api.identity.IdentityManager;
 
 import java.io.File;
 import java.util.HashSet;
+import java.util.List;
 import java.util.Set;
 import java.util.logging.Logger;
 
@@ -20,6 +21,7 @@ import javax.annotation.concurrent.GuardedBy;
 import javax.inject.Inject;
 
 import static android.os.Build.VERSION.SDK_INT;
+import static java.util.Arrays.asList;
 import static java.util.logging.Level.INFO;
 import static org.briarproject.bramble.util.IoUtils.deleteFileOrDir;
 import static org.briarproject.bramble.util.LogUtils.logFileOrDir;
@@ -30,6 +32,12 @@ class AndroidAccountManager extends AccountManagerImpl
 	private static final Logger LOG =
 			Logger.getLogger(AndroidAccountManager.class.getName());
 
+	/**
+	 * Directories that shouldn't be deleted when deleting the user's account.
+	 */
+	private static final List<String> PROTECTED_DIR_NAMES =
+			asList("cache", "code_cache", "lib", "shared_prefs");
+
 	protected final Context appContext;
 	private final SharedPreferences prefs;
 
@@ -81,7 +89,7 @@ class AndroidAccountManager extends AccountManagerImpl
 			if (!prefs.edit().clear().commit())
 				LOG.warning("Could not clear shared preferences");
 		}
-		// Delete files, except lib and shared_prefs directories
+		// Delete files, except protected directories
 		Set<File> files = new HashSet<>();
 		File dataDir = getDataDir();
 		@Nullable
@@ -90,14 +98,12 @@ class AndroidAccountManager extends AccountManagerImpl
 			LOG.warning("Could not list files in app data dir");
 		} else {
 			for (File file : fileArray) {
-				String name = file.getName();
-				if (!name.equals("lib") && !name.equals("shared_prefs")) {
+				if (!PROTECTED_DIR_NAMES.contains(file.getName())) {
 					files.add(file);
 				}
 			}
 		}
 		files.add(appContext.getFilesDir());
-		files.add(appContext.getCacheDir());
 		addIfNotNull(files, appContext.getExternalCacheDir());
 		if (SDK_INT >= 19) {
 			for (File file : appContext.getExternalCacheDirs()) {
@@ -109,12 +115,16 @@ class AndroidAccountManager extends AccountManagerImpl
 				addIfNotNull(files, file);
 			}
 		}
+		// Clear the cache directory but don't delete it
+		File cacheDir = appContext.getCacheDir();
+		File[] children = cacheDir.listFiles();
+		if (children != null) files.addAll(asList(children));
 		for (File file : files) {
+			if (LOG.isLoggable(INFO)) {
+				LOG.info("Deleting " + file.getAbsolutePath());
+			}
 			deleteFileOrDir(file);
 		}
-		// Recreate the cache dir as some OpenGL drivers expect it to exist
-		if (!new File(dataDir, "cache").mkdirs())
-			LOG.warning("Could not recreate cache dir");
 	}
 
 	private File getDataDir() {

bramble-android/src/main/java/org/briarproject/bramble/network/AndroidNetworkManager.java

@@ -32,6 +32,7 @@ import static android.content.Intent.ACTION_SCREEN_OFF;
 import static android.content.Intent.ACTION_SCREEN_ON;
 import static android.net.ConnectivityManager.CONNECTIVITY_ACTION;
 import static android.net.ConnectivityManager.TYPE_WIFI;
+import static android.net.wifi.p2p.WifiP2pManager.WIFI_P2P_THIS_DEVICE_CHANGED_ACTION;
 import static android.os.Build.VERSION.SDK_INT;
 import static android.os.PowerManager.ACTION_DEVICE_IDLE_MODE_CHANGED;
 import static java.util.concurrent.TimeUnit.MINUTES;
@@ -76,9 +77,9 @@ class AndroidNetworkManager implements NetworkManager, Service {
 		filter.addAction(ACTION_SCREEN_ON);
 		filter.addAction(ACTION_SCREEN_OFF);
 		filter.addAction(WIFI_AP_STATE_CHANGED_ACTION);
+		filter.addAction(WIFI_P2P_THIS_DEVICE_CHANGED_ACTION);
 		if (SDK_INT >= 23) filter.addAction(ACTION_DEVICE_IDLE_MODE_CHANGED);
 		appContext.registerReceiver(networkStateReceiver, filter);
-
 	}
 
 	@Override
@@ -136,7 +137,8 @@ class AndroidNetworkManager implements NetworkManager, Service {
 		}
 
 		private boolean isApEvent(@Nullable String action) {
-			return WIFI_AP_STATE_CHANGED_ACTION.equals(action);
+			return WIFI_AP_STATE_CHANGED_ACTION.equals(action) ||
+					WIFI_P2P_THIS_DEVICE_CHANGED_ACTION.equals(action);
 		}
 	}
 }

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

@@ -8,24 +8,34 @@ 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.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.Collection;
-import java.util.Collections;
+import java.util.HashMap;
 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;
@@ -47,12 +57,25 @@ 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
@@ -61,7 +84,9 @@ class AndroidBluetoothPlugin extends BluetoothPlugin<BluetoothServerSocket> {
 	private static final Logger LOG =
 			getLogger(AndroidBluetoothPlugin.class.getName());
 
-	private static final int MAX_DISCOVERY_MS = 10_000;
+	private static final int MIN_DEVICE_DISCOVERY_MS = 2_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;
@@ -135,17 +160,42 @@ 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() {
@@ -200,7 +250,8 @@ class AndroidBluetoothPlugin extends BluetoothPlugin<BluetoothServerSocket> {
 	@Nullable
 	DuplexTransportConnection discoverAndConnect(String uuid) {
 		if (adapter == null) return null;
-		for (String address : discoverDevices()) {
+		for (BluetoothDevice d : discoverDevices()) {
+			String address = d.getAddress();
 			try {
 				if (LOG.isLoggable(INFO))
 					LOG.info("Connecting to " + scrubMacAddress(address));
@@ -216,10 +267,184 @@ class AndroidBluetoothPlugin extends BluetoothPlugin<BluetoothServerSocket> {
 		return null;
 	}
 
-	private Collection<String> discoverDevices() {
-		List<String> addresses = new ArrayList<>();
+	@Override
+	public boolean supportsDiscovery() {
+		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<>();
-		DiscoveryReceiver receiver = new DiscoveryReceiver(intents);
+		QueueingReceiver receiver = new QueueingReceiver(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);
@@ -227,8 +452,9 @@ class AndroidBluetoothPlugin extends BluetoothPlugin<BluetoothServerSocket> {
 		appContext.registerReceiver(receiver, filter);
 		try {
 			if (adapter.startDiscovery()) {
-				long now = clock.currentTimeMillis();
-				long end = now + MAX_DISCOVERY_MS;
+				long start = clock.currentTimeMillis();
+				long end = start + MAX_DEVICE_DISCOVERY_MS;
+				long now = start;
 				while (now < end) {
 					Intent i = intents.poll(end - now, MILLISECONDS);
 					if (i == null) break;
@@ -237,14 +463,27 @@ class AndroidBluetoothPlugin extends BluetoothPlugin<BluetoothServerSocket> {
 						LOG.info("Discovery started");
 					} else if (ACTION_DISCOVERY_FINISHED.equals(action)) {
 						LOG.info("Discovery finished");
-						break;
+						now = clock.currentTimeMillis();
+						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 = i.getParcelableExtra(EXTRA_DEVICE);
-						String address = d.getAddress();
-						if (LOG.isLoggable(INFO))
-							LOG.info("Discovered " + scrubMacAddress(address));
-						if (!addresses.contains(address))
-							addresses.add(address);
+						BluetoothDevice d = requireNonNull(
+								i.getParcelableExtra(EXTRA_DEVICE));
+						// Ignore Bluetooth LE devices
+						if (SDK_INT < 18 || d.getType() != DEVICE_TYPE_LE) {
+							if (LOG.isLoggable(INFO)) {
+								LOG.info("Discovered "
+										+ scrubMacAddress(d.getAddress()));
+							}
+							if (!devices.contains(d)) devices.add(d);
+						}
 					}
 					now = clock.currentTimeMillis();
 				}
@@ -259,9 +498,9 @@ class AndroidBluetoothPlugin extends BluetoothPlugin<BluetoothServerSocket> {
 			adapter.cancelDiscovery();
 			appContext.unregisterReceiver(receiver);
 		}
-		// Shuffle the addresses so we don't always try the same one first
-		Collections.shuffle(addresses);
-		return addresses;
+		// Shuffle the devices so we don't always try the same one first
+		shuffle(devices);
+		return devices;
 	}
 
 	private class BluetoothStateReceiver extends BroadcastReceiver {
@@ -282,11 +521,11 @@ class AndroidBluetoothPlugin extends BluetoothPlugin<BluetoothServerSocket> {
 		}
 	}
 
-	private static class DiscoveryReceiver extends BroadcastReceiver {
+	private static class QueueingReceiver extends BroadcastReceiver {
 
 		private final BlockingQueue<Intent> intents;
 
-		private DiscoveryReceiver(BlockingQueue<Intent> intents) {
+		private QueueingReceiver(BlockingQueue<Intent> intents) {
 			this.intents = intents;
 		}
 

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

@@ -9,17 +9,17 @@ 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;
 import java.net.Socket;
 import java.net.UnknownHostException;
-import java.util.Collection;
+import java.util.List;
 import java.util.concurrent.Executor;
 import java.util.logging.Logger;
 
@@ -32,27 +32,18 @@ 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 implements EventListener {
+class AndroidLanTcpPlugin extends LanTcpPlugin {
 
 	private static final Logger LOG =
 			getLogger(AndroidLanTcpPlugin.class.getName());
 
-	private static final byte[] WIFI_AP_ADDRESS_BYTES =
-			{(byte) 192, (byte) 168, 43, 1};
-	private static final InetAddress WIFI_AP_ADDRESS;
-
-	static {
-		try {
-			WIFI_AP_ADDRESS = InetAddress.getByAddress(WIFI_AP_ADDRESS_BYTES);
-		} catch (UnknownHostException e) {
-			// Should only be thrown if the address has an illegal length
-			throw new AssertionError(e);
-		}
-	}
-
 	private final Executor connectionStatusExecutor;
 	private final ConnectivityManager connectivityManager;
 	@Nullable
@@ -62,8 +53,9 @@ class AndroidLanTcpPlugin extends LanTcpPlugin implements EventListener {
 
 	AndroidLanTcpPlugin(Executor ioExecutor, Context appContext,
 			Backoff backoff, PluginCallback callback, int maxLatency,
-			int maxIdleTime) {
-		super(ioExecutor, backoff, callback, maxLatency, maxIdleTime);
+			int maxIdleTime, int connectionTimeout) {
+		super(ioExecutor, backoff, callback, maxLatency, maxIdleTime,
+				connectionTimeout);
 		// Don't execute more than one connection status check at a time
 		connectionStatusExecutor =
 				new PoliteExecutor("AndroidLanTcpPlugin", ioExecutor, 1);
@@ -79,32 +71,31 @@ class AndroidLanTcpPlugin extends LanTcpPlugin implements EventListener {
 	@Override
 	public void start() {
 		if (used.getAndSet(true)) throw new IllegalStateException();
-		running = true;
+		initialisePortProperty();
+		Settings settings = callback.getSettings();
+		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();
 	}
 
 	@Override
-	protected Collection<InetAddress> getLocalIpAddresses() {
+	protected List<InetAddress> getUsableLocalInetAddresses() {
 		// If the device doesn't have wifi, don't open any sockets
 		if (wifiManager == null) return emptyList();
-		// If we're connected to a wifi network, use that network
+		// If we're connected to a wifi network, return its address
 		WifiInfo info = wifiManager.getConnectionInfo();
-		if (info != null && info.getIpAddress() != 0)
+		if (info != null && info.getIpAddress() != 0) {
 			return singletonList(intToInetAddress(info.getIpAddress()));
+		}
 		// If we're running an access point, return its address
-		if (super.getLocalIpAddresses().contains(WIFI_AP_ADDRESS))
-			return singletonList(WIFI_AP_ADDRESS);
+		for (InetAddress addr : getLocalInetAddresses()) {
+			if (addr.equals(WIFI_AP_ADDRESS)) return singletonList(addr);
+			if (addr.equals(WIFI_DIRECT_AP_ADDRESS)) return singletonList(addr);
+		}
 		// No suitable addresses
 		return emptyList();
 	}
@@ -138,29 +129,38 @@ class AndroidLanTcpPlugin extends LanTcpPlugin implements EventListener {
 
 	@Override
 	public void eventOccurred(Event e) {
+		super.eventOccurred(e);
 		if (e instanceof NetworkStatusEvent) updateConnectionStatus();
 	}
 
 	private void updateConnectionStatus() {
 		connectionStatusExecutor.execute(() -> {
-			if (!running) return;
-			Collection<InetAddress> addrs = getLocalIpAddresses();
-			if (addrs.contains(WIFI_AP_ADDRESS)) {
+			State s = getState();
+			if (s != ACTIVE && s != INACTIVE) return;
+			List<InetAddress> addrs = getLocalInetAddresses();
+			if (addrs.contains(WIFI_AP_ADDRESS)
+					|| addrs.contains(WIFI_DIRECT_AP_ADDRESS)) {
 				LOG.info("Providing wifi hotspot");
 				// There's no corresponding Network object and thus no way
 				// to get a suitable socket factory, so we won't be able to
 				// make outgoing connections on API 21+ if another network
 				// has internet access
 				socketFactory = SocketFactory.getDefault();
-				if (socket == null || socket.isClosed()) bind();
+				if (s == INACTIVE) bind();
 			} else if (addrs.isEmpty()) {
 				LOG.info("Not connected to wifi");
 				socketFactory = SocketFactory.getDefault();
-				tryToClose(socket);
+				// Server socket may not have been closed automatically when
+				// 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 (socket == null || socket.isClosed()) bind();
+				if (s == INACTIVE) bind();
 			}
 		});
 	}

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

@@ -21,10 +21,11 @@ import static org.briarproject.bramble.api.plugin.LanTcpConstants.ID;
 @NotNullByDefault
 public class AndroidLanTcpPluginFactory 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 int MAX_LATENCY = 30_000; // 30 seconds
+	private static final int MAX_IDLE_TIME = 30_000; // 30 seconds
+	private static final int CONNECTION_TIMEOUT = 3_000; // 3 seconds
+	private static final int MIN_POLLING_INTERVAL = 60_000; // 1 minute
+	private static final int MAX_POLLING_INTERVAL = 600_000; // 10 mins
 	private static final double BACKOFF_BASE = 1.2;
 
 	private final Executor ioExecutor;
@@ -55,7 +56,8 @@ public class AndroidLanTcpPluginFactory implements DuplexPluginFactory {
 		Backoff backoff = backoffFactory.createBackoff(MIN_POLLING_INTERVAL,
 				MAX_POLLING_INTERVAL, BACKOFF_BASE);
 		AndroidLanTcpPlugin plugin = new AndroidLanTcpPlugin(ioExecutor,
-				appContext, backoff, callback, MAX_LATENCY, MAX_IDLE_TIME);
+				appContext, backoff, callback, MAX_LATENCY, MAX_IDLE_TIME,
+				CONNECTION_TIMEOUT);
 		eventBus.addListener(plugin);
 		return plugin;
 	}

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

@@ -74,7 +74,6 @@ 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.getNetworkCountryIso();
+		return tm == null ? "" : tm.getNetworkCountryIso();
 	}
 
 	private String getCountryFromSimCard() {
 		Object o = appContext.getSystemService(TELEPHONY_SERVICE);
 		TelephonyManager tm = (TelephonyManager) o;
-		return tm.getSimCountryIso();
+		return tm == null ? "" : tm.getSimCountryIso();
 	}
 }

bramble-android/src/test/java/org/briarproject/bramble/account/AndroidAccountManagerTest.java

@@ -72,7 +72,9 @@ public class AndroidAccountManagerTest extends BrambleMockTestCase {
 	@Test
 	public void testDeleteAccountClearsSharedPrefsAndDeletesFiles()
 			throws Exception {
-		// Directories 'lib' and 'shared_prefs' should be spared
+		// Directories 'code_cache', 'lib' and 'shared_prefs' should be spared
+		File codeCacheDir = new File(testDir, "code_cache");
+		File codeCacheFile = new File(codeCacheDir, "file");
 		File libDir = new File(testDir, "lib");
 		File libFile = new File(libDir, "file");
 		File sharedPrefsDir = new File(testDir, "shared_prefs");
@@ -111,6 +113,8 @@ public class AndroidAccountManagerTest extends BrambleMockTestCase {
 
 		assertTrue(dbDir.mkdirs());
 		assertTrue(keyDir.mkdirs());
+		assertTrue(codeCacheDir.mkdirs());
+		assertTrue(codeCacheFile.createNewFile());
 		assertTrue(libDir.mkdirs());
 		assertTrue(libFile.createNewFile());
 		assertTrue(sharedPrefsDir.mkdirs());
@@ -126,6 +130,8 @@ public class AndroidAccountManagerTest extends BrambleMockTestCase {
 
 		assertFalse(dbDir.exists());
 		assertFalse(keyDir.exists());
+		assertTrue(codeCacheDir.exists());
+		assertTrue(codeCacheFile.exists());
 		assertTrue(libDir.exists());
 		assertTrue(libFile.exists());
 		assertTrue(sharedPrefsDir.exists());

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

@@ -18,6 +18,8 @@ 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/plugin/BluetoothConstants.java

@@ -8,6 +8,4 @@ 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

@@ -0,0 +1,18 @@
+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/LanTcpConstants.java

@@ -4,10 +4,10 @@ public interface LanTcpConstants {
 
 	TransportId ID = new TransportId("org.briarproject.bramble.lan");
 
-	// a transport property (shared with contacts)
+	// Transport properties (shared with contacts)
 	String PROP_IP_PORTS = "ipPorts";
+	String PROP_PORT = "port";
 
-	// a local setting
+	// A local setting
 	String PREF_LAN_IP_PORTS = "ipPorts";
-
 }

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

@@ -3,12 +3,55 @@ 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.Collection;
+import java.util.List;
 
 @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.
 	 */
@@ -35,9 +78,18 @@ public interface Plugin {
 	void stop() throws PluginException;
 
 	/**
-	 * Returns true if the plugin is running.
+	 * Returns the current state of the plugin.
 	 */
-	boolean isRunning();
+	State getState();
+
+	/**
+	 * 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
@@ -54,6 +106,5 @@ public interface Plugin {
 	 * Attempts to create connections using the given transport properties,
 	 * passing any created connections to the corresponding handlers.
 	 */
-	void poll(Collection<Pair<TransportProperties, ConnectionHandler>>
-			properties);
+	void poll(List<Pair<TransportProperties, ConnectionHandler>> properties);
 }

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

@@ -1,6 +1,10 @@
 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;
 
@@ -32,12 +36,17 @@ public interface PluginCallback extends ConnectionHandler {
 	void mergeLocalProperties(TransportProperties p);
 
 	/**
-	 * Signals that the transport is enabled.
+	 * Informs the callback of the plugin's current state.
+	 * <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 transportEnabled();
-
-	/**
-	 * Signals that the transport is disabled.
-	 */
-	void transportDisabled();
+	void pluginStateChanged(State state);
 }

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

@@ -41,4 +41,17 @@ 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

@@ -21,6 +21,21 @@ 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/DuplexPlugin.java

@@ -1,14 +1,18 @@
 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;
 
 /**
@@ -58,4 +62,16 @@ 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/event/TransportActiveEvent.java

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

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

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

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

@@ -0,0 +1,32 @@
+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 the {@link State state} of a plugin changes.
+ */
+@Immutable
+@NotNullByDefault
+public class TransportStateEvent extends Event {
+
+	private final TransportId transportId;
+	private final State state;
+
+	public TransportStateEvent(TransportId transportId, State state) {
+		this.transportId = transportId;
+		this.state = state;
+	}
+
+	public TransportId getTransportId() {
+		return transportId;
+	}
+
+	public State getState() {
+		return state;
+	}
+}

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

@@ -8,6 +8,7 @@ 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;
@@ -18,8 +19,9 @@ 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.TransportDisabledEvent;
-import org.briarproject.bramble.api.plugin.event.TransportEnabledEvent;
+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.plugin.simplex.SimplexPlugin;
 import org.briarproject.bramble.api.plugin.simplex.SimplexPluginFactory;
 import org.briarproject.bramble.api.properties.TransportProperties;
@@ -36,6 +38,7 @@ 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;
@@ -45,6 +48,9 @@ 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;
@@ -177,6 +183,26 @@ 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;
@@ -250,7 +276,8 @@ class PluginManagerImpl implements PluginManager, Service {
 	private class Callback implements PluginCallback {
 
 		private final TransportId id;
-		private final AtomicBoolean enabled = new AtomicBoolean(false);
+		private final AtomicReference<State> state =
+				new AtomicReference<>(STARTING_STOPPING);
 
 		private Callback(TransportId id) {
 			this.id = id;
@@ -278,11 +305,7 @@ class PluginManagerImpl implements PluginManager, Service {
 
 		@Override
 		public void mergeSettings(Settings s) {
-			try {
-				settingsManager.mergeSettings(s, id.getString());
-			} catch (DbException e) {
-				logException(LOG, WARNING, e);
-			}
+			PluginManagerImpl.this.mergeSettings(s, id.getString());
 		}
 
 		@Override
@@ -295,15 +318,20 @@ class PluginManagerImpl implements PluginManager, Service {
 		}
 
 		@Override
-		public void transportEnabled() {
-			if (!enabled.getAndSet(true))
-				eventBus.broadcast(new TransportEnabledEvent(id));
-		}
-
-		@Override
-		public void transportDisabled() {
-			if (enabled.getAndSet(false))
-				eventBus.broadcast(new TransportDisabledEvent(id));
+		public void pluginStateChanged(State newState) {
+			State oldState = state.getAndSet(newState);
+			if (newState != oldState) {
+				if (LOG.isLoggable(INFO)) {
+					LOG.info(id + " changed from state " + oldState
+							+ " to " + newState);
+				}
+				eventBus.broadcast(new TransportStateEvent(id, newState));
+				if (newState == ACTIVE) {
+					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

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

@@ -9,10 +9,13 @@ 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;
@@ -29,23 +32,28 @@ import org.briarproject.bramble.api.settings.event.SettingsUpdatedEvent;
 
 import java.io.IOException;
 import java.security.SecureRandom;
-import java.util.Collection;
+import java.util.List;
 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;
@@ -68,9 +76,9 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 	private final int maxLatency;
 	private final AtomicBoolean used = new AtomicBoolean(false);
 
-	private volatile boolean running = false, contactConnections = false;
+	protected final PluginState state = new PluginState();
+
 	private volatile String contactConnectionsUuid = null;
-	private volatile SS socket = null;
 
 	abstract void initialiseAdapter() throws IOException;
 
@@ -119,14 +127,18 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 		LOG.info("Bluetooth enabled");
 		// We may not have been able to get the local address before
 		ioExecutor.execute(this::updateProperties);
-		if (shouldAllowContactConnections()) bind();
+		if (getState() == INACTIVE) bind();
 	}
 
 	void onAdapterDisabled() {
 		LOG.info("Bluetooth disabled");
-		tryToClose(socket);
 		connectionLimiter.allConnectionsClosed();
-		callback.transportDisabled();
+		// The server socket may not have been closed automatically
+		SS ss = state.clearServerSocket();
+		if (ss != null) {
+			LOG.info("Closing server socket");
+			tryToClose(ss);
+		}
 	}
 
 	@Override
@@ -148,31 +160,24 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 	@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();
-		running = true;
-		loadSettings(callback.getSettings());
-		if (shouldAllowContactConnections()) {
+		if (enabledByUser) {
 			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 (!isRunning() || !shouldAllowContactConnections()) return;
+			if (getState() != INACTIVE) return;
 			// Bind a server socket to accept connections from contacts
 			SS ss;
 			try {
@@ -181,14 +186,13 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 				logException(LOG, WARNING, e);
 				return;
 			}
-			if (!isRunning() || !shouldAllowContactConnections()) {
+			if (!state.setServerSocket(ss)) {
+				LOG.info("Closing redundant server socket");
 				tryToClose(ss);
 				return;
 			}
-			socket = ss;
 			backoff.reset();
-			callback.transportEnabled();
-			acceptContactConnections();
+			acceptContactConnections(ss);
 		});
 	}
 
@@ -217,34 +221,39 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 		if (changed) callback.mergeLocalProperties(p);
 	}
 
-	private void acceptContactConnections() {
+	private void acceptContactConnections(SS ss) {
 		while (true) {
 			DuplexTransportConnection conn;
 			try {
-				conn = acceptConnection(socket);
+				conn = acceptConnection(ss);
 			} catch (IOException e) {
-				// This is expected when the socket is closed
-				if (LOG.isLoggable(INFO)) LOG.info(e.toString());
+				// This is expected when the server socket is closed
+				LOG.info("Server socket closed");
+				state.clearServerSocket();
 				return;
 			}
+			LOG.info("Connection received");
 			backoff.reset();
 			if (connectionLimiter.contactConnectionOpened(conn))
 				callback.handleConnection(conn);
-			if (!running) return;
 		}
 	}
 
 	@Override
 	public void stop() {
-		running = false;
-		tryToClose(socket);
-		callback.transportDisabled();
+		SS ss = state.setStopped();
+		tryToClose(ss);
 		disableAdapterIfEnabledByUs();
 	}
 
 	@Override
-	public boolean isRunning() {
-		return running && isAdapterEnabled();
+	public State getState() {
+		return state.getState();
+	}
+
+	@Override
+	public int getReasonsDisabled() {
+		return state.getReasonsDisabled();
 	}
 
 	@Override
@@ -258,9 +267,9 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 	}
 
 	@Override
-	public void poll(Collection<Pair<TransportProperties, ConnectionHandler>>
-			properties) {
-		if (!isRunning() || !shouldAllowContactConnections()) return;
+	public void poll(
+			List<Pair<TransportProperties, ConnectionHandler>> properties) {
+		if (getState() != ACTIVE) return;
 		backoff.increment();
 		for (Pair<TransportProperties, ConnectionHandler> p : properties) {
 			connect(p.getFirst(), p.getSecond());
@@ -273,7 +282,7 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 		String uuid = p.get(PROP_UUID);
 		if (isNullOrEmpty(uuid)) return;
 		ioExecutor.execute(() -> {
-			if (!isRunning() || !shouldAllowContactConnections()) return;
+			if (getState() != ACTIVE) return;
 			if (!connectionLimiter.canOpenContactConnection()) return;
 			DuplexTransportConnection d = createConnection(p);
 			if (d != null) {
@@ -317,7 +326,7 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 
 	@Override
 	public DuplexTransportConnection createConnection(TransportProperties p) {
-		if (!isRunning() || !shouldAllowContactConnections()) return null;
+		if (getState() != ACTIVE) return null;
 		if (!connectionLimiter.canOpenContactConnection()) return null;
 		String address = p.get(PROP_ADDRESS);
 		if (isNullOrEmpty(address)) return null;
@@ -336,7 +345,7 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 
 	@Override
 	public KeyAgreementListener createKeyAgreementListener(byte[] commitment) {
-		if (!isRunning()) return null;
+		if (getState() != ACTIVE) 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);
@@ -348,7 +357,7 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 			logException(LOG, WARNING, e);
 			return null;
 		}
-		if (!isRunning()) {
+		if (getState() != ACTIVE) {
 			tryToClose(ss);
 			return null;
 		}
@@ -362,7 +371,7 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 	@Override
 	public DuplexTransportConnection createKeyAgreementConnection(
 			byte[] commitment, BdfList descriptor) {
-		if (!isRunning()) return null;
+		if (getState() != ACTIVE) return null;
 		// No truncation necessary because COMMIT_LENGTH = 16
 		String uuid = UUID.nameUUIDFromBytes(commitment).toString();
 		DuplexTransportConnection conn;
@@ -403,6 +412,17 @@ 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) {
@@ -422,17 +442,17 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 		}
 	}
 
+	@IoExecutor
 	private void onSettingsUpdated(Settings settings) {
-		boolean wasAllowed = shouldAllowContactConnections();
-		loadSettings(settings);
-		boolean isAllowed = shouldAllowContactConnections();
-		if (wasAllowed && !isAllowed) {
-			LOG.info("Contact connections disabled");
-			tryToClose(socket);
-			callback.transportDisabled();
+		boolean enabledByUser = settings.getBoolean(PREF_PLUGIN_ENABLE, false);
+		SS ss = state.setEnabledByUser(enabledByUser);
+		State s = getState();
+		if (ss != null) {
+			LOG.info("Disabled by user, closing server socket");
+			tryToClose(ss);
 			disableAdapterIfEnabledByUs();
-		} else if (!wasAllowed && isAllowed) {
-			LOG.info("Contact connections enabled");
+		} else if (s == INACTIVE) {
+			LOG.info("Enabled by user, opening server socket");
 			if (isAdapterEnabled()) bind();
 			else enableAdapter();
 		}
@@ -460,4 +480,70 @@ 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

@@ -16,6 +16,7 @@ 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;
 
@@ -45,7 +46,7 @@ abstract class FilePlugin implements SimplexPlugin {
 
 	@Override
 	public TransportConnectionReader createReader(TransportProperties p) {
-		if (!isRunning()) return null;
+		if (getState() != ACTIVE) return null;
 		String path = p.get(PROP_PATH);
 		if (isNullOrEmpty(path)) return null;
 		try {
@@ -60,7 +61,7 @@ abstract class FilePlugin implements SimplexPlugin {
 
 	@Override
 	public TransportConnectionWriter createWriter(TransportProperties p) {
-		if (!isRunning()) return null;
+		if (getState() != ACTIVE) 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

@@ -11,24 +11,25 @@ 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;
 import java.net.InetAddress;
 import java.net.InetSocketAddress;
+import java.net.InterfaceAddress;
 import java.net.ServerSocket;
 import java.net.Socket;
-import java.net.SocketAddress;
 import java.net.UnknownHostException;
 import java.util.ArrayList;
-import java.util.Comparator;
 import java.util.List;
+import java.util.Random;
 import java.util.concurrent.Executor;
 import java.util.logging.Logger;
 
+import javax.annotation.Nullable;
+
+import static java.lang.Integer.parseInt;
 import static java.util.Collections.addAll;
-import static java.util.Collections.emptyList;
 import static java.util.Collections.sort;
 import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
@@ -37,7 +38,9 @@ import static org.briarproject.bramble.api.keyagreement.KeyAgreementConstants.TR
 import static org.briarproject.bramble.api.plugin.LanTcpConstants.ID;
 import static org.briarproject.bramble.api.plugin.LanTcpConstants.PREF_LAN_IP_PORTS;
 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;
@@ -47,15 +50,36 @@ class LanTcpPlugin extends TcpPlugin {
 
 	private static final Logger LOG = getLogger(LanTcpPlugin.class.getName());
 
-	private static final LanAddressComparator ADDRESS_COMPARATOR =
-			new LanAddressComparator();
-
 	private static final int MAX_ADDRESSES = 4;
 	private static final String SEPARATOR = ",";
 
+	/**
+	 * The IP address of an Android device providing a wifi access point.
+	 */
+	protected static final InetAddress WIFI_AP_ADDRESS;
+
+	/**
+	 * The IP address of an Android device providing a wifi direct
+	 * legacy mode access point.
+	 */
+	protected static final InetAddress WIFI_DIRECT_AP_ADDRESS;
+
+	static {
+		try {
+			WIFI_AP_ADDRESS = InetAddress.getByAddress(
+					new byte[] {(byte) 192, (byte) 168, 43, 1});
+			WIFI_DIRECT_AP_ADDRESS = InetAddress.getByAddress(
+					new byte[] {(byte) 192, (byte) 168, 49, 1});
+		} catch (UnknownHostException e) {
+			// Should only be thrown if the address has an illegal length
+			throw new AssertionError(e);
+		}
+	}
+
 	LanTcpPlugin(Executor ioExecutor, Backoff backoff, PluginCallback callback,
-			int maxLatency, int maxIdleTime) {
-		super(ioExecutor, backoff, callback, maxLatency, maxIdleTime);
+			int maxLatency, int maxIdleTime, int connectionTimeout) {
+		super(ioExecutor, backoff, callback, maxLatency, maxIdleTime,
+				connectionTimeout);
 	}
 
 	@Override
@@ -64,37 +88,82 @@ class LanTcpPlugin extends TcpPlugin {
 	}
 
 	@Override
-	protected List<InetSocketAddress> getLocalSocketAddresses() {
-		// Use the same address and port as last time if available
+	public void start() {
+		if (used.getAndSet(true)) throw new IllegalStateException();
+		initialisePortProperty();
+		Settings settings = callback.getSettings();
+		state.setStarted(settings.getBoolean(PREF_PLUGIN_ENABLE, false));
+		bind();
+	}
+
+	protected void initialisePortProperty() {
 		TransportProperties p = callback.getLocalProperties();
+		if (isNullOrEmpty(p.get(PROP_PORT))) {
+			int port = new Random().nextInt(32768) + 32768;
+			p.put(PROP_PORT, String.valueOf(port));
+			callback.mergeLocalProperties(p);
+		}
+	}
+
+	@Override
+	protected List<InetSocketAddress> getLocalSocketAddresses() {
+		TransportProperties p = callback.getLocalProperties();
+		int preferredPort = parsePortProperty(p.get(PROP_PORT));
 		String oldIpPorts = p.get(PROP_IP_PORTS);
 		List<InetSocketAddress> olds = parseSocketAddresses(oldIpPorts);
+
 		List<InetSocketAddress> locals = new ArrayList<>();
-		for (InetAddress local : getLocalIpAddresses()) {
-			if (isAcceptableAddress(local)) {
-				// If this is the old address, try to use the same port
-				for (InetSocketAddress old : olds) {
-					if (old.getAddress().equals(local))
-						locals.add(new InetSocketAddress(local, old.getPort()));
+		List<InetSocketAddress> fallbacks = new ArrayList<>();
+		for (InetAddress local : getUsableLocalInetAddresses()) {
+			// If we've used this address before, try to use the same port
+			int port = preferredPort;
+			for (InetSocketAddress old : olds) {
+				if (old.getAddress().equals(local)) {
+					port = old.getPort();
+					break;
 				}
-				locals.add(new InetSocketAddress(local, 0));
 			}
+			locals.add(new InetSocketAddress(local, port));
+			// Fall back to any available port
+			fallbacks.add(new InetSocketAddress(local, 0));
 		}
-		sort(locals, ADDRESS_COMPARATOR);
+		locals.addAll(fallbacks);
 		return locals;
 	}
 
+	private int parsePortProperty(@Nullable String portProperty) {
+		if (isNullOrEmpty(portProperty)) return 0;
+		try {
+			return parseInt(portProperty);
+		} catch (NumberFormatException e) {
+			return 0;
+		}
+	}
+
 	private List<InetSocketAddress> parseSocketAddresses(String ipPorts) {
-		if (isNullOrEmpty(ipPorts)) return emptyList();
-		String[] split = ipPorts.split(SEPARATOR);
 		List<InetSocketAddress> addresses = new ArrayList<>();
-		for (String ipPort : split) {
+		if (isNullOrEmpty(ipPorts)) return addresses;
+		for (String ipPort : ipPorts.split(SEPARATOR)) {
 			InetSocketAddress a = parseSocketAddress(ipPort);
 			if (a != null) addresses.add(a);
 		}
 		return addresses;
 	}
 
+	protected List<InetAddress> getUsableLocalInetAddresses() {
+		List<InterfaceAddress> ifAddrs =
+				new ArrayList<>(getLocalInterfaceAddresses());
+		// Prefer longer network prefixes
+		sort(ifAddrs, (a, b) ->
+				b.getNetworkPrefixLength() - a.getNetworkPrefixLength());
+		List<InetAddress> addrs = new ArrayList<>();
+		for (InterfaceAddress ifAddr : ifAddrs) {
+			InetAddress addr = ifAddr.getAddress();
+			if (isAcceptableAddress(addr)) addrs.add(addr);
+		}
+		return addrs;
+	}
+
 	@Override
 	protected void setLocalSocketAddress(InetSocketAddress a) {
 		String ipPort = getIpPortString(a);
@@ -132,7 +201,20 @@ class LanTcpPlugin extends TcpPlugin {
 	@Override
 	protected List<InetSocketAddress> getRemoteSocketAddresses(
 			TransportProperties p) {
-		return parseSocketAddresses(p.get(PROP_IP_PORTS));
+		String ipPorts = p.get(PROP_IP_PORTS);
+		List<InetSocketAddress> remotes = parseSocketAddresses(ipPorts);
+		int port = parsePortProperty(p.get(PROP_PORT));
+		// If the contact has a preferred port, we can guess their IP:port when
+		// they're providing a wifi access point
+		if (port != 0) {
+			InetSocketAddress wifiAp =
+					new InetSocketAddress(WIFI_AP_ADDRESS, port);
+			if (!remotes.contains(wifiAp)) remotes.add(wifiAp);
+			InetSocketAddress wifiDirectAp =
+					new InetSocketAddress(WIFI_DIRECT_AP_ADDRESS, port);
+			if (!remotes.contains(wifiDirectAp)) remotes.add(wifiDirectAp);
+		}
+		return remotes;
 	}
 
 	private boolean isAcceptableAddress(InetAddress a) {
@@ -145,52 +227,33 @@ class LanTcpPlugin extends TcpPlugin {
 	}
 
 	@Override
-	protected boolean isConnectable(InetSocketAddress remote) {
+	protected boolean isConnectable(InterfaceAddress local,
+			InetSocketAddress remote) {
 		if (remote.getPort() == 0) return false;
 		if (!isAcceptableAddress(remote.getAddress())) return false;
 		// Try to determine whether the address is on the same LAN as us
-		if (socket == null) return false;
-		byte[] localIp = socket.getInetAddress().getAddress();
+		byte[] localIp = local.getAddress().getAddress();
 		byte[] remoteIp = remote.getAddress().getAddress();
-		return addressesAreOnSameLan(localIp, remoteIp);
+		int prefixLength = local.getNetworkPrefixLength();
+		return areAddressesInSameNetwork(localIp, remoteIp, prefixLength);
 	}
 
 	// Package access for testing
-	boolean addressesAreOnSameLan(byte[] localIp, byte[] remoteIp) {
-		// 10.0.0.0/8
-		if (isPrefix10(localIp)) return isPrefix10(remoteIp);
-		// 172.16.0.0/12
-		if (isPrefix172(localIp)) return isPrefix172(remoteIp);
-		// 192.168.0.0/16
-		if (isPrefix192(localIp)) return isPrefix192(remoteIp);
-		// Unrecognised prefix - may be compatible
+	static boolean areAddressesInSameNetwork(byte[] localIp, byte[] remoteIp,
+			int prefixLength) {
+		if (localIp.length != remoteIp.length) return false;
+		// Compare the first prefixLength bits of the addresses
+		for (int i = 0; i < prefixLength; i++) {
+			int byteIndex = i >> 3;
+			int bitIndex = i & 7; // 0 to 7
+			int mask = 128 >> bitIndex; // Select the bit at bitIndex
+			if ((localIp[byteIndex] & mask) != (remoteIp[byteIndex] & mask)) {
+				return false; // Addresses differ at bit i
+			}
+		}
 		return true;
 	}
 
-	private static boolean isPrefix10(byte[] ipv4) {
-		return ipv4[0] == 10;
-	}
-
-	private static boolean isPrefix172(byte[] ipv4) {
-		return ipv4[0] == (byte) 172 && (ipv4[1] & 0xF0) == 16;
-	}
-
-	private static boolean isPrefix192(byte[] ipv4) {
-		return ipv4[0] == (byte) 192 && ipv4[1] == (byte) 168;
-	}
-
-	// Returns the prefix length for an RFC 1918 address, or 0 for any other
-	// address
-	private static int getRfc1918PrefixLength(InetAddress addr) {
-		if (!(addr instanceof Inet4Address)) return 0;
-		if (!addr.isSiteLocalAddress()) return 0;
-		byte[] ipv4 = addr.getAddress();
-		if (isPrefix10(ipv4)) return 8;
-		if (isPrefix172(ipv4)) return 12;
-		if (isPrefix192(ipv4)) return 16;
-		return 0;
-	}
-
 	@Override
 	public boolean supportsKeyAgreement() {
 		return true;
@@ -209,10 +272,10 @@ class LanTcpPlugin extends TcpPlugin {
 			} catch (IOException e) {
 				if (LOG.isLoggable(INFO))
 					LOG.info("Failed to bind " + scrubSocketAddress(addr));
-				tryToClose(ss);
+				tryToClose(ss, LOG, WARNING);
 			}
 		}
-		if (ss == null || !ss.isBound()) {
+		if (ss == null) {
 			LOG.info("Could not bind server socket for key agreement");
 			return null;
 		}
@@ -228,7 +291,13 @@ class LanTcpPlugin extends TcpPlugin {
 	@Override
 	public DuplexTransportConnection createKeyAgreementConnection(
 			byte[] commitment, BdfList descriptor) {
-		if (!isRunning()) return null;
+		ServerSocket ss = state.getServerSocket();
+		if (ss == null) return null;
+		InterfaceAddress local = getLocalInterfaceAddress(ss.getInetAddress());
+		if (local == null) {
+			LOG.warning("No interface for key agreement server socket");
+			return null;
+		}
 		InetSocketAddress remote;
 		try {
 			remote = parseSocketAddress(descriptor);
@@ -236,12 +305,11 @@ class LanTcpPlugin extends TcpPlugin {
 			LOG.info("Invalid IP/port in key agreement descriptor");
 			return null;
 		}
-		if (!isConnectable(remote)) {
+		if (!isConnectable(local, remote)) {
 			if (LOG.isLoggable(INFO)) {
-				SocketAddress local = socket.getLocalSocketAddress();
 				LOG.info(scrubSocketAddress(remote) +
 						" is not connectable from " +
-						scrubSocketAddress(local));
+						scrubSocketAddress(ss.getLocalSocketAddress()));
 			}
 			return null;
 		}
@@ -249,8 +317,8 @@ class LanTcpPlugin extends TcpPlugin {
 			if (LOG.isLoggable(INFO))
 				LOG.info("Connecting to " + scrubSocketAddress(remote));
 			Socket s = createSocket();
-			s.bind(new InetSocketAddress(socket.getInetAddress(), 0));
-			s.connect(remote);
+			s.bind(new InetSocketAddress(ss.getInetAddress(), 0));
+			s.connect(remote, connectionTimeout);
 			s.setSoTimeout(socketTimeout);
 			if (LOG.isLoggable(INFO))
 				LOG.info("Connected to " + scrubSocketAddress(remote));
@@ -296,22 +364,7 @@ class LanTcpPlugin extends TcpPlugin {
 
 		@Override
 		public void close() {
-			IoUtils.tryToClose(ss, LOG, WARNING);
-		}
-	}
-
-	static class LanAddressComparator implements Comparator<InetSocketAddress> {
-
-		@Override
-		public int compare(InetSocketAddress a, InetSocketAddress b) {
-			// Prefer addresses with non-zero ports
-			int aPort = a.getPort(), bPort = b.getPort();
-			if (aPort > 0 && bPort == 0) return -1;
-			if (aPort == 0 && bPort > 0) return 1;
-			// Prefer addresses with longer RFC 1918 prefixes
-			int aPrefix = getRfc1918PrefixLength(a.getAddress());
-			int bPrefix = getRfc1918PrefixLength(b.getAddress());
-			return bPrefix - aPrefix;
+			tryToClose(ss, LOG, WARNING);
 		}
 	}
 }

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

@@ -1,5 +1,6 @@
 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;
@@ -18,18 +19,21 @@ import static org.briarproject.bramble.api.plugin.LanTcpConstants.ID;
 @NotNullByDefault
 public class LanTcpPluginFactory 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 int MAX_LATENCY = 30_000; // 30 seconds
+	private static final int MAX_IDLE_TIME = 30_000; // 30 seconds
+	private static final int CONNECTION_TIMEOUT = 3_000; // 3 seconds
+	private static final int MIN_POLLING_INTERVAL = 60_000; // 1 minute
+	private static final int MAX_POLLING_INTERVAL = 600_000; // 10 mins
 	private static final double BACKOFF_BASE = 1.2;
 
 	private final Executor ioExecutor;
+	private final EventBus eventBus;
 	private final BackoffFactory backoffFactory;
 
-	public LanTcpPluginFactory(Executor ioExecutor,
+	public LanTcpPluginFactory(Executor ioExecutor, EventBus eventBus,
 			BackoffFactory backoffFactory) {
 		this.ioExecutor = ioExecutor;
+		this.eventBus = eventBus;
 		this.backoffFactory = backoffFactory;
 	}
 
@@ -47,7 +51,9 @@ public class LanTcpPluginFactory implements DuplexPluginFactory {
 	public DuplexPlugin createPlugin(PluginCallback callback) {
 		Backoff backoff = backoffFactory.createBackoff(MIN_POLLING_INTERVAL,
 				MAX_POLLING_INTERVAL, BACKOFF_BASE);
-		return new LanTcpPlugin(ioExecutor, backoff, callback, MAX_LATENCY,
-				MAX_IDLE_TIME);
+		LanTcpPlugin plugin =  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

@@ -2,27 +2,31 @@ package org.briarproject.bramble.plugin.tcp;
 
 import org.briarproject.bramble.PoliteExecutor;
 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.event.Event;
+import org.briarproject.bramble.api.event.EventListener;
+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.util.IoUtils;
+import org.briarproject.bramble.api.settings.Settings;
+import org.briarproject.bramble.api.settings.event.SettingsUpdatedEvent;
 
 import java.io.IOException;
 import java.net.InetAddress;
 import java.net.InetSocketAddress;
+import java.net.InterfaceAddress;
 import java.net.NetworkInterface;
 import java.net.ServerSocket;
 import java.net.Socket;
-import java.net.SocketAddress;
 import java.net.SocketException;
 import java.net.UnknownHostException;
 import java.util.ArrayList;
@@ -35,20 +39,26 @@ 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.net.NetworkInterface.getNetworkInterfaces;
 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 {
+abstract class TcpPlugin implements DuplexPlugin, EventListener {
 
 	private static final Logger LOG = getLogger(TcpPlugin.class.getName());
 
@@ -58,11 +68,10 @@ abstract class TcpPlugin implements DuplexPlugin {
 	protected final Executor ioExecutor, bindExecutor;
 	protected final Backoff backoff;
 	protected final PluginCallback callback;
-	protected final int maxLatency, maxIdleTime, socketTimeout;
+	protected final int maxLatency, maxIdleTime;
+	protected final int connectionTimeout, socketTimeout;
 	protected final AtomicBoolean used = new AtomicBoolean(false);
-
-	protected volatile boolean running = false;
-	protected volatile ServerSocket socket = null;
+	protected final PluginState state = new PluginState();
 
 	/**
 	 * Returns zero or more socket addresses on which the plugin should listen,
@@ -86,15 +95,18 @@ abstract class TcpPlugin implements DuplexPlugin {
 	/**
 	 * Returns true if connections to the given address can be attempted.
 	 */
-	protected abstract boolean isConnectable(InetSocketAddress remote);
+	@SuppressWarnings("BooleanMethodIsAlwaysInverted")
+	protected abstract boolean isConnectable(InterfaceAddress local,
+			InetSocketAddress remote);
 
 	TcpPlugin(Executor ioExecutor, Backoff backoff, PluginCallback callback,
-			int maxLatency, int maxIdleTime) {
+			int maxLatency, int maxIdleTime, int connectionTimeout) {
 		this.ioExecutor = ioExecutor;
 		this.backoff = backoff;
 		this.callback = callback;
 		this.maxLatency = maxLatency;
 		this.maxIdleTime = maxIdleTime;
+		this.connectionTimeout = connectionTimeout;
 		if (maxIdleTime > Integer.MAX_VALUE / 2)
 			socketTimeout = Integer.MAX_VALUE;
 		else socketTimeout = maxIdleTime * 2;
@@ -115,14 +127,14 @@ abstract class TcpPlugin implements DuplexPlugin {
 	@Override
 	public void start() {
 		if (used.getAndSet(true)) throw new IllegalStateException();
-		running = true;
+		Settings settings = callback.getSettings();
+		state.setStarted(settings.getBoolean(PREF_PLUGIN_ENABLE, false));
 		bind();
 	}
 
 	protected void bind() {
 		bindExecutor.execute(() -> {
-			if (!running) return;
-			if (socket != null && !socket.isClosed()) return;
+			if (getState() != INACTIVE) return;
 			ServerSocket ss = null;
 			for (InetSocketAddress addr : getLocalSocketAddresses()) {
 				try {
@@ -132,34 +144,28 @@ abstract class TcpPlugin implements DuplexPlugin {
 				} catch (IOException e) {
 					if (LOG.isLoggable(INFO))
 						LOG.info("Failed to bind " + scrubSocketAddress(addr));
-					tryToClose(ss);
+					tryToClose(ss, LOG, WARNING);
 				}
 			}
-			if (ss == null || !ss.isBound()) {
+			if (ss == null) {
 				LOG.info("Could not bind server socket");
 				return;
 			}
-			if (!running) {
-				tryToClose(ss);
+			if (!state.setServerSocket(ss)) {
+				LOG.info("Closing redundant server socket");
+				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));
-			callback.transportEnabled();
-			acceptContactConnections();
+			acceptContactConnections(ss);
 		});
 	}
 
-	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('%');
@@ -167,15 +173,16 @@ abstract class TcpPlugin implements DuplexPlugin {
 		return addr + ":" + a.getPort();
 	}
 
-	private void acceptContactConnections() {
-		while (isRunning()) {
+	private void acceptContactConnections(ServerSocket ss) {
+		while (true) {
 			Socket s;
 			try {
-				s = socket.accept();
+				s = ss.accept();
 				s.setSoTimeout(socketTimeout);
 			} catch (IOException e) {
-				// This is expected when the socket is closed
-				if (LOG.isLoggable(INFO)) LOG.info(e.toString());
+				// This is expected when the server socket is closed
+				LOG.info("Server socket closed");
+				state.clearServerSocket(ss);
 				return;
 			}
 			if (LOG.isLoggable(INFO))
@@ -188,13 +195,18 @@ abstract class TcpPlugin implements DuplexPlugin {
 
 	@Override
 	public void stop() {
-		running = false;
-		tryToClose(socket);
+		ServerSocket ss = state.setStopped();
+		tryToClose(ss, LOG, WARNING);
 	}
 
 	@Override
-	public boolean isRunning() {
-		return running && socket != null && !socket.isClosed();
+	public State getState() {
+		return state.getState();
+	}
+
+	@Override
+	public int getReasonsDisabled() {
+		return state.getReasonsDisabled();
 	}
 
 	@Override
@@ -208,9 +220,9 @@ abstract class TcpPlugin implements DuplexPlugin {
 	}
 
 	@Override
-	public void poll(Collection<Pair<TransportProperties, ConnectionHandler>>
-			properties) {
-		if (!isRunning()) return;
+	public void poll(
+			List<Pair<TransportProperties, ConnectionHandler>> properties) {
+		if (getState() != ACTIVE) return;
 		backoff.increment();
 		for (Pair<TransportProperties, ConnectionHandler> p : properties) {
 			connect(p.getFirst(), p.getSecond());
@@ -229,14 +241,24 @@ abstract class TcpPlugin implements DuplexPlugin {
 
 	@Override
 	public DuplexTransportConnection createConnection(TransportProperties p) {
-		if (!isRunning()) return null;
+		ServerSocket ss = state.getServerSocket();
+		if (ss == null) return null;
+		InterfaceAddress local = getLocalInterfaceAddress(ss.getInetAddress());
+		if (local == null) {
+			LOG.warning("No interface for server socket");
+			return null;
+		}
 		for (InetSocketAddress remote : getRemoteSocketAddresses(p)) {
-			if (!isConnectable(remote)) {
+			// Don't try to connect to our own address
+			if (!canConnectToOwnAddress() &&
+					remote.getAddress().equals(ss.getInetAddress())) {
+				continue;
+			}
+			if (!isConnectable(local, remote)) {
 				if (LOG.isLoggable(INFO)) {
-					SocketAddress local = socket.getLocalSocketAddress();
 					LOG.info(scrubSocketAddress(remote) +
 							" is not connectable from " +
-							scrubSocketAddress(local));
+							scrubSocketAddress(ss.getLocalSocketAddress()));
 				}
 				continue;
 			}
@@ -244,8 +266,8 @@ abstract class TcpPlugin implements DuplexPlugin {
 				if (LOG.isLoggable(INFO))
 					LOG.info("Connecting to " + scrubSocketAddress(remote));
 				Socket s = createSocket();
-				s.bind(new InetSocketAddress(socket.getInetAddress(), 0));
-				s.connect(remote);
+				s.bind(new InetSocketAddress(ss.getInetAddress(), 0));
+				s.connect(remote, connectionTimeout);
 				s.setSoTimeout(socketTimeout);
 				if (LOG.isLoggable(INFO))
 					LOG.info("Connected to " + scrubSocketAddress(remote));
@@ -259,6 +281,19 @@ abstract class TcpPlugin implements DuplexPlugin {
 		return null;
 	}
 
+	@Nullable
+	InterfaceAddress getLocalInterfaceAddress(InetAddress a) {
+		for (InterfaceAddress ifAddr : getLocalInterfaceAddresses()) {
+			if (ifAddr.getAddress().equals(a)) return ifAddr;
+		}
+		return null;
+	}
+
+	// Override for testing
+	protected boolean canConnectToOwnAddress() {
+		return false;
+	}
+
 	protected Socket createSocket() throws IOException {
 		return new Socket();
 	}
@@ -287,22 +322,6 @@ abstract class TcpPlugin implements DuplexPlugin {
 		}
 	}
 
-	@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;
@@ -314,17 +333,130 @@ abstract class TcpPlugin implements DuplexPlugin {
 		throw new UnsupportedOperationException();
 	}
 
-	Collection<InetAddress> getLocalIpAddresses() {
+	@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()) {
+			addrs.addAll(iface.getInterfaceAddresses());
+		}
+		return addrs;
+	}
+
+	List<InetAddress> getLocalInetAddresses() {
+		List<InetAddress> addrs = new ArrayList<>();
+		for (NetworkInterface iface : getNetworkInterfaces()) {
+			addrs.addAll(list(iface.getInetAddresses()));
+		}
+		return addrs;
+	}
+
+	private List<NetworkInterface> getNetworkInterfaces() {
 		try {
-			Enumeration<NetworkInterface> ifaces = getNetworkInterfaces();
-			if (ifaces == null) return emptyList();
-			List<InetAddress> addrs = new ArrayList<>();
-			for (NetworkInterface iface : list(ifaces))
-				addrs.addAll(list(iface.getInetAddresses()));
-			return addrs;
+			Enumeration<NetworkInterface> ifaces =
+					NetworkInterface.getNetworkInterfaces();
+			return ifaces == null ? emptyList() : list(ifaces);
 		} catch (SocketException e) {
 			logException(LOG, WARNING, e);
 			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

@@ -1,15 +1,19 @@
 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;
 import java.net.InetAddress;
 import java.net.InetSocketAddress;
+import java.net.InterfaceAddress;
 import java.util.LinkedList;
 import java.util.List;
 import java.util.concurrent.Executor;
@@ -29,8 +33,10 @@ class WanTcpPlugin extends TcpPlugin {
 	private volatile MappingResult mappingResult;
 
 	WanTcpPlugin(Executor ioExecutor, Backoff backoff, PortMapper portMapper,
-			PluginCallback callback, int maxLatency, int maxIdleTime) {
-		super(ioExecutor, backoff, callback, maxLatency, maxIdleTime);
+			PluginCallback callback, int maxLatency, int maxIdleTime,
+			int connectionTimeout) {
+		super(ioExecutor, backoff, callback, maxLatency, maxIdleTime,
+				connectionTimeout);
 		this.portMapper = portMapper;
 	}
 
@@ -39,13 +45,29 @@ 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
 		TransportProperties p = callback.getLocalProperties();
 		InetSocketAddress old = parseSocketAddress(p.get(PROP_IP_PORT));
 		List<InetSocketAddress> addrs = new LinkedList<>();
-		for (InetAddress a : getLocalIpAddresses()) {
+		for (InetAddress a : getLocalInetAddresses()) {
 			if (isAcceptableAddress(a)) {
 				// If this is the old address, try to use the same port
 				if (old != null && old.getAddress().equals(a))
@@ -86,7 +108,8 @@ class WanTcpPlugin extends TcpPlugin {
 	}
 
 	@Override
-	protected boolean isConnectable(InetSocketAddress remote) {
+	protected boolean isConnectable(InterfaceAddress local,
+			InetSocketAddress remote) {
 		if (remote.getPort() == 0) return false;
 		return isAcceptableAddress(remote.getAddress());
 	}

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

@@ -1,5 +1,6 @@
 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;
@@ -19,19 +20,22 @@ import static org.briarproject.bramble.api.plugin.WanTcpConstants.ID;
 @NotNullByDefault
 public class WanTcpPluginFactory 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 int MAX_LATENCY = 30_000; // 30 seconds
+	private static final int MAX_IDLE_TIME = 30_000; // 30 seconds
+	private static final int CONNECTION_TIMEOUT = 30_000; // 30 seconds
+	private static final int MIN_POLLING_INTERVAL = 60_000; // 1 minute
+	private static final int MAX_POLLING_INTERVAL = 600_000; // 10 mins
 	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,
+	public WanTcpPluginFactory(Executor ioExecutor, EventBus eventBus,
 			BackoffFactory backoffFactory, ShutdownManager shutdownManager) {
 		this.ioExecutor = ioExecutor;
+		this.eventBus = eventBus;
 		this.backoffFactory = backoffFactory;
 		this.shutdownManager = shutdownManager;
 	}
@@ -50,8 +54,10 @@ public class WanTcpPluginFactory implements DuplexPluginFactory {
 	public DuplexPlugin createPlugin(PluginCallback callback) {
 		Backoff backoff = backoffFactory.createBackoff(MIN_POLLING_INTERVAL,
 				MAX_POLLING_INTERVAL, BACKOFF_BASE);
-		return new WanTcpPlugin(ioExecutor, backoff,
+		WanTcpPlugin plugin = new WanTcpPlugin(ioExecutor, backoff,
 				new PortMapperImpl(shutdownManager), callback, MAX_LATENCY,
-				MAX_IDLE_TIME);
+				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 bridge connection are likely to work.
+	 * Countries where obfs4 or meek bridge connections 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

@@ -15,9 +15,11 @@ 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;
@@ -54,6 +56,9 @@ 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;
@@ -65,6 +70,11 @@ 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;
@@ -76,6 +86,9 @@ 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;
@@ -113,16 +126,14 @@ 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);
 
-	private volatile ServerSocket socket = null;
+	protected final PluginState state = new PluginState();
+
 	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();
@@ -159,7 +170,6 @@ 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);
@@ -190,7 +200,7 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 			}
 		}
 		// Load the settings
-		settings = callback.getSettings();
+		settings = migrateSettings(callback.getSettings());
 		// Install or update the assets if necessary
 		if (!assetsAreUpToDate()) installAssets();
 		if (cookieFile.exists() && !cookieFile.delete())
@@ -258,7 +268,6 @@ 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));
@@ -266,11 +275,12 @@ 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");
-				connectionStatus.setBootstrapped();
+				state.setBootstrapped();
 			}
 		} catch (IOException e) {
 			throw new PluginException(e);
 		}
+		state.setStarted();
 		// Check whether we're online
 		updateConnectionStatus(networkManager.getNetworkStatus(),
 				batteryManager.isCharging());
@@ -278,6 +288,18 @@ 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();
 	}
@@ -393,11 +415,11 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 				tryToClose(ss, LOG, WARNING);
 				return;
 			}
-			if (!running) {
+			if (!state.setServerSocket(ss)) {
+				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();
@@ -412,7 +434,7 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 	}
 
 	private void publishHiddenService(String port) {
-		if (!running) return;
+		if (!state.isTorRunning()) return;
 		LOG.info("Creating hidden service");
 		String privKey = settings.get(HS_PRIVKEY);
 		Map<Integer, String> portLines = singletonMap(80, "127.0.0.1:" + port);
@@ -450,14 +472,15 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 	}
 
 	private void acceptContactConnections(ServerSocket ss) {
-		while (running) {
+		while (true) {
 			Socket s;
 			try {
 				s = ss.accept();
 				s.setSoTimeout(socketTimeout);
 			} catch (IOException e) {
-				// This is expected when the socket is closed
-				if (LOG.isLoggable(INFO)) LOG.info(e.toString());
+				// This is expected when the server socket is closed
+				LOG.info("Server socket closed");
+				state.clearServerSocket(ss);
 				return;
 			}
 			LOG.info("Connection received");
@@ -467,10 +490,8 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 	}
 
 	protected void enableNetwork(boolean enable) throws IOException {
-		if (!running) return;
-		connectionStatus.enableNetwork(enable);
+		state.enableNetwork(enable);
 		controlConnection.setConf("DisableNetwork", enable ? "0" : "1");
-		if (!enable) callback.transportDisabled();
 	}
 
 	private void enableBridges(boolean enable, boolean needsMeek)
@@ -494,9 +515,8 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 
 	@Override
 	public void stop() {
-		running = false;
-		tryToClose(socket, LOG, WARNING);
-		callback.transportDisabled();
+		ServerSocket ss = state.setStopped();
+		tryToClose(ss, LOG, WARNING);
 		if (controlSocket != null && controlConnection != null) {
 			try {
 				LOG.info("Stopping Tor");
@@ -510,8 +530,13 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 	}
 
 	@Override
-	public boolean isRunning() {
-		return running && connectionStatus.isConnected();
+	public State getState() {
+		return state.getState();
+	}
+
+	@Override
+	public int getReasonsDisabled() {
+		return state.getReasonsDisabled();
 	}
 
 	@Override
@@ -525,9 +550,9 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 	}
 
 	@Override
-	public void poll(Collection<Pair<TransportProperties, ConnectionHandler>>
-			properties) {
-		if (!isRunning()) return;
+	public void poll(
+			List<Pair<TransportProperties, ConnectionHandler>> properties) {
+		if (getState() != ACTIVE) return;
 		backoff.increment();
 		for (Pair<TransportProperties, ConnectionHandler> p : properties) {
 			connect(p.getFirst(), p.getSecond());
@@ -546,7 +571,7 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 
 	@Override
 	public DuplexTransportConnection createConnection(TransportProperties p) {
-		if (!isRunning()) return null;
+		if (getState() != ACTIVE) return null;
 		String bestOnion = null;
 		String onion2 = p.get(PROP_ONION_V2);
 		String onion3 = p.get(PROP_ONION_V3);
@@ -634,8 +659,8 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 								new TorTransportConnection(this, s));
 					}
 				} catch (IOException e) {
-					// This is expected when the socket is closed
-					if (LOG.isLoggable(INFO)) LOG.info(e.toString());
+					// This is expected when the server socket is closed
+					LOG.info("Rendezvous server socket closed");
 				}
 			});
 			Map<Integer, String> portLines =
@@ -660,13 +685,23 @@ 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") &&
-				connectionStatus.getAndSetCircuitBuilt()) {
+				state.getAndSetCircuitBuilt()) {
 			LOG.info("First circuit built");
 			backoff.reset();
-			if (isRunning()) callback.transportEnabled();
 		}
 	}
 
@@ -697,9 +732,8 @@ 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%")) {
-			connectionStatus.setBootstrapped();
+			state.setBootstrapped();
 			backoff.reset();
-			if (isRunning()) callback.transportEnabled();
 		}
 	}
 
@@ -736,7 +770,7 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 	private void disableNetwork() {
 		connectionStatusExecutor.execute(() -> {
 			try {
-				enableNetwork(false);
+				if (state.isTorRunning()) enableNetwork(false);
 			} catch (IOException ex) {
 				logException(LOG, WARNING, ex);
 			}
@@ -746,12 +780,14 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 	private void updateConnectionStatus(NetworkStatus status,
 			boolean charging) {
 		connectionStatusExecutor.execute(() -> {
-			if (!running) return;
+			if (!state.isTorRunning()) 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);
@@ -762,47 +798,70 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 
 			if (LOG.isLoggable(INFO)) {
 				LOG.info("Online: " + online + ", wifi: " + wifi);
-				if ("".equals(country)) LOG.info("Country code unknown");
+				if (country.isEmpty()) LOG.info("Country code unknown");
 				else LOG.info("Country code: " + country);
 				LOG.info("Charging: " + charging);
 			}
 
-			try {
-				if (!online) {
-					LOG.info("Disabling network, device is offline");
-					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);
+			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("Enabling network, using obfs4 bridges");
-						enableBridges(true, false);
+						LOG.info("Not using bridges");
+					}
+					if (wifi && charging) {
+						LOG.info("Enabling connection padding");
+						enableConnectionPadding = true;
+					} else {
+						LOG.info("Disabling connection padding");
 					}
-					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);
+			}
+
+			state.setReasonsDisabled(reasonsDisabled);
+
+			try {
+				if (enableNetwork) {
+					enableBridges(enableBridges, useMeek);
+					enableConnectionPadding(enableConnectionPadding);
 				}
+				enableNetwork(enableNetwork);
 			} catch (IOException e) {
 				logException(LOG, WARNING, e);
 			}
@@ -810,33 +869,96 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 	}
 
 	private void enableConnectionPadding(boolean enable) throws IOException {
-		if (!running) return;
 		controlConnection.setConf("ConnectionPadding", enable ? "1" : "0");
 	}
 
-	private static class ConnectionStatus {
+	@ThreadSafe
+	@NotNullByDefault
+	protected class PluginState {
 
-		// All of the following are locking: this
-		private boolean networkEnabled = false;
-		private boolean bootstrapped = false, circuitBuilt = false;
+		@GuardedBy("this")
+		private boolean started = false,
+				stopped = false,
+				networkInitialised = false,
+				networkEnabled = false,
+				bootstrapped = false,
+				circuitBuilt = false,
+				settingsChecked = false;
 
-		private synchronized void setBootstrapped() {
-			bootstrapped = true;
+		@GuardedBy("this")
+		private int reasonsDisabled = 0;
+
+		@GuardedBy("this")
+		@Nullable
+		private ServerSocket serverSocket = null;
+
+		synchronized void setStarted() {
+			started = true;
+			callback.pluginStateChanged(getState());
 		}
 
-		private synchronized boolean getAndSetCircuitBuilt() {
+		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() {
 			boolean firstCircuit = !circuitBuilt;
 			circuitBuilt = true;
+			callback.pluginStateChanged(getState());
 			return firstCircuit;
 		}
 
-		private synchronized void enableNetwork(boolean enable) {
+		synchronized void enableNetwork(boolean enable) {
+			networkInitialised = true;
 			networkEnabled = enable;
 			if (!enable) circuitBuilt = false;
+			callback.pluginStateChanged(getState());
 		}
 
-		private synchronized boolean isConnected() {
-			return networkEnabled && bootstrapped && circuitBuilt;
+		synchronized void setReasonsDisabled(int reasonsDisabled) {
+			settingsChecked = true;
+			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/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.TransportDisabledEvent;
-import org.briarproject.bramble.api.plugin.event.TransportEnabledEvent;
+import org.briarproject.bramble.api.plugin.event.TransportActiveEvent;
+import org.briarproject.bramble.api.plugin.event.TransportInactiveEvent;
 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 TransportEnabledEvent) {
-			TransportEnabledEvent t = (TransportEnabledEvent) e;
+		} else if (e instanceof TransportActiveEvent) {
+			TransportActiveEvent t = (TransportActiveEvent) e;
 			addTransportAsync(t.getTransportId());
-		} else if (e instanceof TransportDisabledEvent) {
-			TransportDisabledEvent t = (TransportDisabledEvent) e;
+		} else if (e instanceof TransportInactiveEvent) {
+			TransportInactiveEvent t = (TransportInactiveEvent) 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.TransportEnabledEvent;
+import org.briarproject.bramble.api.plugin.event.TransportActiveEvent;
 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 TransportEnabledEvent) {
-			TransportEnabledEvent t = (TransportEnabledEvent) e;
+		if (e instanceof TransportActiveEvent) {
+			TransportActiveEvent t = (TransportActiveEvent) e;
 			if (t.getTransportId().equals(TorConstants.ID))
 				ioExecutor.execute(this::sendReports);
 		}

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.TransportDisabledEvent;
-import org.briarproject.bramble.api.plugin.event.TransportEnabledEvent;
+import org.briarproject.bramble.api.plugin.event.TransportActiveEvent;
+import org.briarproject.bramble.api.plugin.event.TransportInactiveEvent;
 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.CollectionMatcher.collectionOf;
+import static org.briarproject.bramble.test.ListMatcher.listOf;
 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 testPollsOnTransportEnabled() throws Exception {
+	public void testPollsOnTransportActivated() throws Exception {
 		DuplexPlugin plugin = context.mock(DuplexPlugin.class);
 
 		context.checking(new Expectations() {{
@@ -351,17 +351,20 @@ 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(collectionOf(
-					pairOf(equal(properties), any(ConnectionHandler.class)))));
+			oneOf(plugin).poll(with(listOf(pairOf(
+					equal(properties), any(ConnectionHandler.class)))));
 		}});
 
-		poller.eventOccurred(new TransportEnabledEvent(transportId));
+		poller.eventOccurred(new TransportActiveEvent(transportId));
 	}
 
 	@Test
@@ -394,6 +397,9 @@ 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)));
@@ -402,11 +408,11 @@ public class PollerImplTest extends BrambleMockTestCase {
 			// All contacts are connected, so don't poll the plugin
 		}});
 
-		poller.eventOccurred(new TransportEnabledEvent(transportId));
+		poller.eventOccurred(new TransportActiveEvent(transportId));
 	}
 
 	@Test
-	public void testCancelsPollingOnTransportDisabled() {
+	public void testCancelsPollingOnTransportDeactivated() {
 		Plugin plugin = context.mock(Plugin.class);
 
 		context.checking(new Expectations() {{
@@ -424,11 +430,11 @@ public class PollerImplTest extends BrambleMockTestCase {
 			oneOf(scheduler).schedule(with(any(Runnable.class)), with(0L),
 					with(MILLISECONDS));
 			will(returnValue(future));
-			// The plugin is disabled before the task runs - cancel the task
+			// The plugin is deactivated before the task runs - cancel the task
 			oneOf(future).cancel(false);
 		}});
 
-		poller.eventOccurred(new TransportEnabledEvent(transportId));
-		poller.eventOccurred(new TransportDisabledEvent(transportId));
+		poller.eventOccurred(new TransportActiveEvent(transportId));
+		poller.eventOccurred(new TransportInactiveEvent(transportId));
 	}
 }

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

@@ -4,15 +4,15 @@ 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;
-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.settings.Settings;
-import org.briarproject.bramble.plugin.tcp.LanTcpPlugin.LanAddressComparator;
 import org.briarproject.bramble.test.BrambleTestCase;
+import org.junit.Before;
 import org.junit.Test;
 
 import java.io.IOException;
@@ -22,7 +22,6 @@ import java.net.InetSocketAddress;
 import java.net.NetworkInterface;
 import java.net.ServerSocket;
 import java.net.Socket;
-import java.util.Comparator;
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.atomic.AtomicBoolean;
@@ -33,56 +32,90 @@ 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;
 import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertTrue;
+import static org.junit.Assume.assumeTrue;
 
 public class LanTcpPluginTest extends BrambleTestCase {
 
 	private final Backoff backoff = new TestBackoff();
 	private final ExecutorService ioExecutor = newCachedThreadPool();
 
+	private Callback callback = null;
+	private LanTcpPlugin plugin = null;
+
+	@Before
+	public void setUp() {
+		callback = new Callback();
+		plugin = new LanTcpPlugin(ioExecutor, backoff, callback, 0, 0, 1000) {
+			@Override
+			protected boolean canConnectToOwnAddress() {
+				return true;
+			}
+		};
+	}
+
 	@Test
-	public void testAddressesAreOnSameLan() {
-		Callback callback = new Callback();
-		LanTcpPlugin plugin = new LanTcpPlugin(ioExecutor, backoff, callback,
-				0, 0);
-		// Local and remote in 10.0.0.0/8 should return true
-		assertTrue(plugin.addressesAreOnSameLan(makeAddress(10, 0, 0, 0),
-				makeAddress(10, 255, 255, 255)));
-		// Local and remote in 172.16.0.0/12 should return true
-		assertTrue(plugin.addressesAreOnSameLan(makeAddress(172, 16, 0, 0),
-				makeAddress(172, 31, 255, 255)));
-		// Local and remote in 192.168.0.0/16 should return true
-		assertTrue(plugin.addressesAreOnSameLan(makeAddress(192, 168, 0, 0),
-				makeAddress(192, 168, 255, 255)));
-		// Local and remote in 169.254.0.0/16 (link-local) should return true
-		assertTrue(plugin.addressesAreOnSameLan(makeAddress(169, 254, 0, 0),
-				makeAddress(169, 254, 255, 255)));
-		// Local and remote in different recognised prefixes should return false
-		assertFalse(plugin.addressesAreOnSameLan(makeAddress(10, 0, 0, 0),
-				makeAddress(172, 31, 255, 255)));
-		assertFalse(plugin.addressesAreOnSameLan(makeAddress(10, 0, 0, 0),
-				makeAddress(192, 168, 255, 255)));
-		assertFalse(plugin.addressesAreOnSameLan(makeAddress(172, 16, 0, 0),
-				makeAddress(10, 255, 255, 255)));
-		assertFalse(plugin.addressesAreOnSameLan(makeAddress(172, 16, 0, 0),
-				makeAddress(192, 168, 255, 255)));
-		assertFalse(plugin.addressesAreOnSameLan(makeAddress(192, 168, 0, 0),
-				makeAddress(10, 255, 255, 255)));
-		assertFalse(plugin.addressesAreOnSameLan(makeAddress(192, 168, 0, 0),
-				makeAddress(172, 31, 255, 255)));
-		// Remote prefix unrecognised should return false
-		assertFalse(plugin.addressesAreOnSameLan(makeAddress(10, 0, 0, 0),
-				makeAddress(1, 2, 3, 4)));
-		assertFalse(plugin.addressesAreOnSameLan(makeAddress(172, 16, 0, 0),
-				makeAddress(1, 2, 3, 4)));
-		assertFalse(plugin.addressesAreOnSameLan(makeAddress(192, 168, 0, 0),
-				makeAddress(1, 2, 3, 4)));
-		// Both prefixes unrecognised should return true (could be link-local)
-		assertTrue(plugin.addressesAreOnSameLan(makeAddress(1, 2, 3, 4),
-				makeAddress(5, 6, 7, 8)));
+	public void testAreAddressesInSameNetwork() {
+		// Local and remote in 10.0.0.0/8
+		assertTrue(areAddressesInSameNetwork(makeAddress(10, 0, 0, 0),
+				makeAddress(10, 255, 255, 255), 8));
+		assertFalse(areAddressesInSameNetwork(makeAddress(10, 0, 0, 0),
+				makeAddress(10, 255, 255, 255), 9));
+
+		// Local and remote in 172.16.0.0/12
+		assertTrue(areAddressesInSameNetwork(makeAddress(172, 16, 0, 0),
+				makeAddress(172, 31, 255, 255), 12));
+		assertFalse(areAddressesInSameNetwork(makeAddress(172, 16, 0, 0),
+				makeAddress(172, 31, 255, 255), 13));
+
+		// Local and remote in 192.168.0.0/16
+		assertTrue(areAddressesInSameNetwork(makeAddress(192, 168, 0, 0),
+				makeAddress(192, 168, 255, 255), 16));
+		assertFalse(areAddressesInSameNetwork(makeAddress(192, 168, 0, 0),
+				makeAddress(192, 168, 255, 255), 17));
+
+		// Local and remote in 169.254.0.0/16
+		assertTrue(areAddressesInSameNetwork(makeAddress(169, 254, 0, 0),
+				makeAddress(169, 254, 255, 255), 16));
+		assertFalse(areAddressesInSameNetwork(makeAddress(169, 254, 0, 0),
+				makeAddress(169, 254, 255, 255), 17));
+
+		// Local in 10.0.0.0/8, remote in a different network
+		assertFalse(areAddressesInSameNetwork(makeAddress(10, 0, 0, 0),
+				makeAddress(172, 31, 255, 255), 8));
+		assertFalse(areAddressesInSameNetwork(makeAddress(10, 0, 0, 0),
+				makeAddress(192, 168, 255, 255), 8));
+		assertFalse(areAddressesInSameNetwork(makeAddress(10, 0, 0, 0),
+				makeAddress(169, 254, 255, 255), 8));
+
+		// Local in 172.16.0.0/12, remote in a different network
+		assertFalse(areAddressesInSameNetwork(makeAddress(172, 16, 0, 0),
+				makeAddress(10, 255, 255, 255), 12));
+		assertFalse(areAddressesInSameNetwork(makeAddress(172, 16, 0, 0),
+				makeAddress(192, 168, 255, 255), 12));
+		assertFalse(areAddressesInSameNetwork(makeAddress(172, 16, 0, 0),
+				makeAddress(169, 254, 255, 255), 12));
+
+		// Local in 192.168.0.0/16, remote in a different network
+		assertFalse(areAddressesInSameNetwork(makeAddress(192, 168, 0, 0),
+				makeAddress(10, 255, 255, 255), 16));
+		assertFalse(areAddressesInSameNetwork(makeAddress(192, 168, 0, 0),
+				makeAddress(172, 31, 255, 255), 16));
+		assertFalse(areAddressesInSameNetwork(makeAddress(192, 168, 0, 0),
+				makeAddress(169, 254, 255, 255), 16));
+
+		// Local in 169.254.0.0/16, remote in a different network
+		assertFalse(areAddressesInSameNetwork(makeAddress(169, 254, 0, 0),
+				makeAddress(10, 255, 255, 255), 16));
+		assertFalse(areAddressesInSameNetwork(makeAddress(169, 254, 0, 0),
+				makeAddress(172, 31, 255, 255), 16));
+		assertFalse(areAddressesInSameNetwork(makeAddress(169, 254, 0, 0),
+				makeAddress(192, 168, 255, 255), 16));
 	}
 
 	private byte[] makeAddress(int... parts) {
@@ -93,13 +126,7 @@ public class LanTcpPluginTest extends BrambleTestCase {
 
 	@Test
 	public void testIncomingConnection() throws Exception {
-		if (!systemHasLocalIpv4Address()) {
-			System.err.println("WARNING: Skipping test, no local IPv4 address");
-			return;
-		}
-		Callback callback = new Callback();
-		DuplexPlugin plugin = new LanTcpPlugin(ioExecutor, backoff, callback,
-				0, 0);
+		assumeTrue(systemHasLocalIpv4Address());
 		plugin.start();
 		// The plugin should have bound a socket and stored the port number
 		assertTrue(callback.propertiesLatch.await(5, SECONDS));
@@ -128,13 +155,7 @@ public class LanTcpPluginTest extends BrambleTestCase {
 
 	@Test
 	public void testOutgoingConnection() throws Exception {
-		if (!systemHasLocalIpv4Address()) {
-			System.err.println("WARNING: Skipping test, no local IPv4 address");
-			return;
-		}
-		Callback callback = new Callback();
-		DuplexPlugin plugin = new LanTcpPlugin(ioExecutor, backoff, callback,
-				0, 0);
+		assumeTrue(systemHasLocalIpv4Address());
 		plugin.start();
 		// The plugin should have bound a socket and stored the port number
 		assertTrue(callback.propertiesLatch.await(5, SECONDS));
@@ -177,13 +198,7 @@ public class LanTcpPluginTest extends BrambleTestCase {
 
 	@Test
 	public void testIncomingKeyAgreementConnection() throws Exception {
-		if (!systemHasLocalIpv4Address()) {
-			System.err.println("WARNING: Skipping test, no local IPv4 address");
-			return;
-		}
-		Callback callback = new Callback();
-		DuplexPlugin plugin = new LanTcpPlugin(ioExecutor, backoff, callback,
-				0, 0);
+		assumeTrue(systemHasLocalIpv4Address());
 		plugin.start();
 		assertTrue(callback.propertiesLatch.await(5, SECONDS));
 		KeyAgreementListener kal =
@@ -225,13 +240,7 @@ public class LanTcpPluginTest extends BrambleTestCase {
 
 	@Test
 	public void testOutgoingKeyAgreementConnection() throws Exception {
-		if (!systemHasLocalIpv4Address()) {
-			System.err.println("WARNING: Skipping test, no local IPv4 address");
-			return;
-		}
-		Callback callback = new Callback();
-		DuplexPlugin plugin = new LanTcpPlugin(ioExecutor, backoff, callback,
-				0, 0);
+		assumeTrue(systemHasLocalIpv4Address());
 		plugin.start();
 		// The plugin should have bound a socket and stored the port number
 		assertTrue(callback.propertiesLatch.await(5, SECONDS));
@@ -276,62 +285,12 @@ public class LanTcpPluginTest extends BrambleTestCase {
 		plugin.stop();
 	}
 
-	@Test
-	public void testComparatorPrefersNonZeroPorts() {
-		Comparator<InetSocketAddress> comparator = new LanAddressComparator();
-		InetSocketAddress nonZero = new InetSocketAddress("1.2.3.4", 1234);
-		InetSocketAddress zero = new InetSocketAddress("1.2.3.4", 0);
-
-		assertEquals(0, comparator.compare(nonZero, nonZero));
-		assertTrue(comparator.compare(nonZero, zero) < 0);
-
-		assertTrue(comparator.compare(zero, nonZero) > 0);
-		assertEquals(0, comparator.compare(zero, zero));
-	}
-
-	@Test
-	public void testComparatorPrefersLongerPrefixes() {
-		Comparator<InetSocketAddress> comparator = new LanAddressComparator();
-		InetSocketAddress prefix192 = new InetSocketAddress("192.168.0.1", 0);
-		InetSocketAddress prefix172 = new InetSocketAddress("172.16.0.1", 0);
-		InetSocketAddress prefix10 = new InetSocketAddress("10.0.0.1", 0);
-
-		assertEquals(0, comparator.compare(prefix192, prefix192));
-		assertTrue(comparator.compare(prefix192, prefix172) < 0);
-		assertTrue(comparator.compare(prefix192, prefix10) < 0);
-
-		assertTrue(comparator.compare(prefix172, prefix192) > 0);
-		assertEquals(0, comparator.compare(prefix172, prefix172));
-		assertTrue(comparator.compare(prefix172, prefix10) < 0);
-
-		assertTrue(comparator.compare(prefix10, prefix192) > 0);
-		assertTrue(comparator.compare(prefix10, prefix172) > 0);
-		assertEquals(0, comparator.compare(prefix10, prefix10));
-	}
-
-	@Test
-	public void testComparatorPrefersSiteLocalToLinkLocal() {
-		Comparator<InetSocketAddress> comparator = new LanAddressComparator();
-		InetSocketAddress prefix192 = new InetSocketAddress("192.168.0.1", 0);
-		InetSocketAddress prefix172 = new InetSocketAddress("172.16.0.1", 0);
-		InetSocketAddress prefix10 = new InetSocketAddress("10.0.0.1", 0);
-		InetSocketAddress linkLocal = new InetSocketAddress("169.254.0.1", 0);
-
-		assertTrue(comparator.compare(prefix192, linkLocal) < 0);
-		assertTrue(comparator.compare(prefix172, linkLocal) < 0);
-		assertTrue(comparator.compare(prefix10, linkLocal) < 0);
-
-		assertTrue(comparator.compare(linkLocal, prefix192) > 0);
-		assertTrue(comparator.compare(linkLocal, prefix172) > 0);
-		assertTrue(comparator.compare(linkLocal, prefix10) > 0);
-		assertEquals(0, comparator.compare(linkLocal, linkLocal));
-	}
-
 	private boolean systemHasLocalIpv4Address() throws Exception {
 		for (NetworkInterface i : list(getNetworkInterfaces())) {
 			for (InetAddress a : list(i.getInetAddresses())) {
-				if (a instanceof Inet4Address)
+				if (a instanceof Inet4Address) {
 					return a.isLinkLocalAddress() || a.isSiteLocalAddress();
+				}
 			}
 		}
 		return false;
@@ -340,13 +299,20 @@ public class LanTcpPluginTest extends BrambleTestCase {
 	@NotNullByDefault
 	private static class Callback implements PluginCallback {
 
-		private final CountDownLatch propertiesLatch = new CountDownLatch(1);
+		// Properties will be stored twice: the preferred port at startup,
+		// and the IP:port when the server socket is bound
+		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 new Settings();
+			return settings;
 		}
 
 		@Override
@@ -365,11 +331,7 @@ public class LanTcpPluginTest extends BrambleTestCase {
 		}
 
 		@Override
-		public void transportEnabled() {
-		}
-
-		@Override
-		public void transportDisabled() {
+		public void pluginStateChanged(State newState) {
 		}
 
 		@Override

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.TransportDisabledEvent;
-import org.briarproject.bramble.api.plugin.event.TransportEnabledEvent;
+import org.briarproject.bramble.api.plugin.event.TransportActiveEvent;
+import org.briarproject.bramble.api.plugin.event.TransportInactiveEvent;
 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.CollectionMatcher.collectionOf;
+import static org.briarproject.bramble.test.ListMatcher.listOf;
 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();
 
-		// Enable the transport - no endpoints should be created yet
+		// Activate the transport - no endpoints should be created yet
 		expectGetPlugin();
 
-		rendezvousPoller.eventOccurred(new TransportEnabledEvent(transportId));
+		rendezvousPoller.eventOccurred(new TransportActiveEvent(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(collectionOf(pairOf(
+			oneOf(plugin).poll(with(listOf(pairOf(
 					equal(transportProperties),
 					any(ConnectionHandler.class)))));
 		}});
@@ -212,8 +212,8 @@ public class RendezvousPollerImplTest extends BrambleMockTestCase {
 				new PendingContactRemovedEvent(pendingContact.getId()));
 		context.assertIsSatisfied();
 
-		// Disable the transport - endpoint is already closed
-		rendezvousPoller.eventOccurred(new TransportDisabledEvent(transportId));
+		// Deactivate the transport - endpoint is already closed
+		rendezvousPoller.eventOccurred(new TransportInactiveEvent(transportId));
 	}
 
 	@Test
@@ -230,10 +230,10 @@ public class RendezvousPollerImplTest extends BrambleMockTestCase {
 		rendezvousPoller.startService();
 		context.assertIsSatisfied();
 
-		// Enable the transport - no endpoints should be created yet
+		// Activate the transport - no endpoints should be created yet
 		expectGetPlugin();
 
-		rendezvousPoller.eventOccurred(new TransportEnabledEvent(transportId));
+		rendezvousPoller.eventOccurred(new TransportActiveEvent(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(collectionOf(pairOf(
+			oneOf(plugin).poll(with(listOf(pairOf(
 					equal(transportProperties),
 					any(ConnectionHandler.class)))));
 		}});
@@ -269,12 +269,12 @@ public class RendezvousPollerImplTest extends BrambleMockTestCase {
 				new PendingContactRemovedEvent(pendingContact.getId()));
 		context.assertIsSatisfied();
 
-		// Disable the transport - endpoint is already closed
-		rendezvousPoller.eventOccurred(new TransportDisabledEvent(transportId));
+		// Deactivate the transport - endpoint is already closed
+		rendezvousPoller.eventOccurred(new TransportInactiveEvent(transportId));
 	}
 
 	@Test
-	public void testCreatesAndClosesEndpointsWhenTransportIsEnabledAndDisabled()
+	public void testCreatesAndClosesEndpointsWhenTransportIsActivatedAndDeactivated()
 			throws Exception {
 		long beforeExpiry = pendingContact.getTimestamp();
 
@@ -292,19 +292,19 @@ public class RendezvousPollerImplTest extends BrambleMockTestCase {
 				new PendingContactAddedEvent(pendingContact));
 		context.assertIsSatisfied();
 
-		// Enable the transport - endpoint should be created
+		// Activate the transport - endpoint should be created
 		expectGetPlugin();
 		expectCreateEndpoint();
 		expectStateChangedEvent(WAITING_FOR_CONNECTION);
 
-		rendezvousPoller.eventOccurred(new TransportEnabledEvent(transportId));
+		rendezvousPoller.eventOccurred(new TransportActiveEvent(transportId));
 		context.assertIsSatisfied();
 
-		// Disable the transport - endpoint should be closed
+		// Deactivate the transport - endpoint should be closed
 		expectCloseEndpoint();
 		expectStateChangedEvent(OFFLINE);
 
-		rendezvousPoller.eventOccurred(new TransportDisabledEvent(transportId));
+		rendezvousPoller.eventOccurred(new TransportInactiveEvent(transportId));
 		context.assertIsSatisfied();
 
 		// Remove the pending contact - endpoint is already closed

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

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

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

@@ -37,9 +37,9 @@ public class DesktopPluginModule extends PluginModule {
 						backoffFactory);
 		DuplexPluginFactory modem = new ModemPluginFactory(ioExecutor,
 				reliabilityFactory);
-		DuplexPluginFactory lan = new LanTcpPluginFactory(ioExecutor,
+		DuplexPluginFactory lan = new LanTcpPluginFactory(ioExecutor, eventBus,
 				backoffFactory);
-		DuplexPluginFactory wan = new WanTcpPluginFactory(ioExecutor,
+		DuplexPluginFactory wan = new WanTcpPluginFactory(ioExecutor, eventBus,
 				backoffFactory, shutdownManager);
 		Collection<DuplexPluginFactory> duplex =
 				asList(bluetooth, modem, lan, wan);

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

@@ -4,8 +4,10 @@ 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;
@@ -19,13 +21,20 @@ import org.briarproject.bramble.api.rendezvous.RendezvousEndpoint;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
-import java.util.Collection;
+import java.util.List;
 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;
 
@@ -44,8 +53,8 @@ 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,
@@ -75,6 +84,7 @@ 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);
@@ -83,18 +93,20 @@ class ModemPlugin implements DuplexPlugin, Modem.Callback {
 				if (!modem.start()) continue;
 				if (LOG.isLoggable(INFO))
 					LOG.info("Initialised modem on " + portName);
-				running = true;
+				state.setInitialised();
 				return;
 			} catch (IOException e) {
 				logException(LOG, WARNING, e);
 			}
 		}
+		LOG.warning("Failed to initialised modem");
+		state.setFailed();
 		throw new PluginException();
 	}
 
 	@Override
 	public void stop() {
-		running = false;
+		state.setStopped();
 		if (modem != null) {
 			try {
 				modem.stop();
@@ -105,8 +117,13 @@ class ModemPlugin implements DuplexPlugin, Modem.Callback {
 	}
 
 	@Override
-	public boolean isRunning() {
-		return running;
+	public State getState() {
+		return state.getState();
+	}
+
+	@Override
+	public int getReasonsDisabled() {
+		return 0;
 	}
 
 	@Override
@@ -120,13 +137,13 @@ class ModemPlugin implements DuplexPlugin, Modem.Callback {
 	}
 
 	@Override
-	public void poll(Collection<Pair<TransportProperties, ConnectionHandler>>
-			properties) {
+	public void poll(
+			List<Pair<TransportProperties, ConnectionHandler>> properties) {
 		throw new UnsupportedOperationException();
 	}
 
-	private boolean resetModem() {
-		if (!running) return false;
+	private void resetModem() {
+		if (getState() != ACTIVE) return;
 		for (String portName : serialPortList.getPortNames()) {
 			if (LOG.isLoggable(INFO))
 				LOG.info("Trying to initialise modem on " + portName);
@@ -135,18 +152,18 @@ class ModemPlugin implements DuplexPlugin, Modem.Callback {
 				if (!modem.start()) continue;
 				if (LOG.isLoggable(INFO))
 					LOG.info("Initialised modem on " + portName);
-				return true;
+				return;
 			} catch (IOException e) {
 				logException(LOG, WARNING, e);
 			}
 		}
-		running = false;
-		return false;
+		LOG.warning("Failed to initialise modem");
+		state.setFailed();
 	}
 
 	@Override
 	public DuplexTransportConnection createConnection(TransportProperties p) {
-		if (!running) return null;
+		if (getState() != ACTIVE) return null;
 		// Get the ISO 3166 code for the caller's country
 		String fromIso = callback.getLocalProperties().get("iso3166");
 		if (isNullOrEmpty(fromIso)) return null;
@@ -197,6 +214,17 @@ 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");
@@ -232,4 +260,41 @@ 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

@@ -9,6 +9,8 @@ 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;
 
@@ -33,6 +35,7 @@ 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
@@ -50,6 +53,7 @@ public class ModemPluginTest extends BrambleMockTestCase {
 			will(returnValue(modem));
 			oneOf(modem).start();
 			will(returnValue(true));
+			oneOf(callback).pluginStateChanged(ACTIVE);
 		}});
 
 		plugin.start();
@@ -65,12 +69,14 @@ 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));
@@ -93,12 +99,14 @@ 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));
@@ -121,12 +129,14 @@ 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

@@ -32,6 +32,7 @@ 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;
@@ -141,10 +142,10 @@ public class BridgeTest extends BrambleTestCase {
 			plugin.start();
 			long start = clock.currentTimeMillis();
 			while (clock.currentTimeMillis() - start < TIMEOUT) {
-				if (plugin.isRunning()) return;
+				if (plugin.getState() == ACTIVE) return;
 				clock.sleep(500);
 			}
-			if (!plugin.isRunning()) {
+			if (plugin.getState() != ACTIVE) {
 				fail("Could not connect to Tor within timeout.");
 			}
 		} finally {

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

@@ -1,6 +1,7 @@
 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;
@@ -30,11 +31,7 @@ public class TestPluginCallback implements PluginCallback {
 	}
 
 	@Override
-	public void transportEnabled() {
-	}
-
-	@Override
-	public void transportDisabled() {
+	public void pluginStateChanged(State state) {
 	}
 
 	@Override

briar-android/build.gradle

@@ -22,8 +22,8 @@ android {
 	defaultConfig {
 		minSdkVersion 16
 		targetSdkVersion 28
-		versionCode 10205
-		versionName "1.2.5"
+		versionCode 10207
+		versionName "1.2.7"
 		applicationId "org.briarproject.briar.android"
 		buildConfigField "String", "GitHash",
 				"\"${getStdout(['git', 'rev-parse', '--short=7', 'HEAD'], 'No commit hash')}\""
@@ -98,7 +98,7 @@ dependencies {
 	implementation 'androidx.lifecycle:lifecycle-extensions:2.1.0'
 	implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
 	implementation 'com.google.android.material:material:1.1.0-beta01'
-	implementation 'androidx.recyclerview:recyclerview-selection:1.0.0'
+	implementation 'androidx.recyclerview:recyclerview-selection:1.1.0-rc01'
 
 	implementation 'ch.acra:acra:4.11'
 	implementation 'info.guardianproject.panic:panic:1.0'

briar-android/src/androidTestOfficial/java/org/briarproject/briar/android/attachment/AttachmentRetrieverIntegrationTest.java

@@ -13,9 +13,8 @@ import java.util.Random;
 import androidx.test.ext.junit.runners.AndroidJUnit4;
 
 import static androidx.test.InstrumentationRegistry.getContext;
-import static org.briarproject.briar.android.attachment.AttachmentItem.State.AVAILABLE;
-import static org.briarproject.briar.android.attachment.AttachmentItem.State.ERROR;
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
 
 @RunWith(AndroidJUnit4.class)
@@ -28,7 +27,7 @@ public class AttachmentRetrieverIntegrationTest {
 
 	private final ImageHelper imageHelper = new ImageHelperImpl();
 	private final AttachmentRetriever retriever =
-			new AttachmentRetrieverImpl(null, null, dimensions, imageHelper,
+			new AttachmentRetrieverImpl(null, dimensions, imageHelper,
 					new ImageSizeCalculator(imageHelper));
 
 	@Test
@@ -36,7 +35,7 @@ public class AttachmentRetrieverIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/jpeg");
 		InputStream is = getAssetInputStream("kitten_small.jpg");
 		Attachment a = new Attachment(h, is);
-		AttachmentItem item = retriever.createAttachmentItem(a, true);
+		AttachmentItem item = retriever.getAttachmentItem(a, true);
 		assertEquals(msgId, item.getMessageId());
 		assertEquals(160, item.getWidth());
 		assertEquals(240, item.getHeight());
@@ -44,7 +43,7 @@ public class AttachmentRetrieverIntegrationTest {
 		assertEquals(240, item.getThumbnailHeight());
 		assertEquals("image/jpeg", item.getMimeType());
 		assertJpgOrJpeg(item.getExtension());
-		assertEquals(AVAILABLE, item.getState());
+		assertFalse(item.hasError());
 	}
 
 	@Test
@@ -52,7 +51,7 @@ public class AttachmentRetrieverIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/jpeg");
 		InputStream is = getAssetInputStream("kitten_original.jpg");
 		Attachment a = new Attachment(h, is);
-		AttachmentItem item = retriever.createAttachmentItem(a, true);
+		AttachmentItem item = retriever.getAttachmentItem(a, true);
 		assertEquals(msgId, item.getMessageId());
 		assertEquals(1728, item.getWidth());
 		assertEquals(2592, item.getHeight());
@@ -60,7 +59,7 @@ public class AttachmentRetrieverIntegrationTest {
 		assertEquals(dimensions.maxHeight, item.getThumbnailHeight());
 		assertEquals("image/jpeg", item.getMimeType());
 		assertJpgOrJpeg(item.getExtension());
-		assertEquals(AVAILABLE, item.getState());
+		assertFalse(item.hasError());
 	}
 
 	@Test
@@ -68,7 +67,7 @@ public class AttachmentRetrieverIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/png");
 		InputStream is = getAssetInputStream("kitten.png");
 		Attachment a = new Attachment(h, is);
-		AttachmentItem item = retriever.createAttachmentItem(a, true);
+		AttachmentItem item = retriever.getAttachmentItem(a, true);
 		assertEquals(msgId, item.getMessageId());
 		assertEquals(737, item.getWidth());
 		assertEquals(510, item.getHeight());
@@ -76,7 +75,7 @@ public class AttachmentRetrieverIntegrationTest {
 		assertEquals(138, item.getThumbnailHeight());
 		assertEquals("image/png", item.getMimeType());
 		assertEquals("png", item.getExtension());
-		assertEquals(AVAILABLE, item.getState());
+		assertFalse(item.hasError());
 	}
 
 	@Test
@@ -84,14 +83,14 @@ public class AttachmentRetrieverIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/gif");
 		InputStream is = getAssetInputStream("uber.gif");
 		Attachment a = new Attachment(h, is);
-		AttachmentItem item = retriever.createAttachmentItem(a, true);
+		AttachmentItem item = retriever.getAttachmentItem(a, true);
 		assertEquals(1, item.getWidth());
 		assertEquals(1, item.getHeight());
 		assertEquals(dimensions.minHeight, item.getThumbnailWidth());
 		assertEquals(dimensions.minHeight, item.getThumbnailHeight());
 		assertEquals("image/gif", item.getMimeType());
 		assertEquals("gif", item.getExtension());
-		assertEquals(AVAILABLE, item.getState());
+		assertFalse(item.hasError());
 	}
 
 	@Test
@@ -99,14 +98,14 @@ public class AttachmentRetrieverIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/jpeg");
 		InputStream is = getAssetInputStream("lottapixel.jpg");
 		Attachment a = new Attachment(h, is);
-		AttachmentItem item = retriever.createAttachmentItem(a, true);
+		AttachmentItem item = retriever.getAttachmentItem(a, true);
 		assertEquals(64250, item.getWidth());
 		assertEquals(64250, item.getHeight());
 		assertEquals(dimensions.maxWidth, item.getThumbnailWidth());
 		assertEquals(dimensions.maxWidth, item.getThumbnailHeight());
 		assertEquals("image/jpeg", item.getMimeType());
 		assertJpgOrJpeg(item.getExtension());
-		assertEquals(AVAILABLE, item.getState());
+		assertFalse(item.hasError());
 	}
 
 	@Test
@@ -114,14 +113,14 @@ public class AttachmentRetrieverIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/png");
 		InputStream is = getAssetInputStream("image_io_crash.png");
 		Attachment a = new Attachment(h, is);
-		AttachmentItem item = retriever.createAttachmentItem(a, true);
+		AttachmentItem item = retriever.getAttachmentItem(a, true);
 		assertEquals(1184, item.getWidth());
 		assertEquals(448, item.getHeight());
 		assertEquals(dimensions.maxWidth, item.getThumbnailWidth());
 		assertEquals(dimensions.minHeight, item.getThumbnailHeight());
 		assertEquals("image/png", item.getMimeType());
 		assertEquals("png", item.getExtension());
-		assertEquals(AVAILABLE, item.getState());
+		assertFalse(item.hasError());
 	}
 
 	@Test
@@ -129,14 +128,14 @@ public class AttachmentRetrieverIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/gif");
 		InputStream is = getAssetInputStream("gimp_crash.gif");
 		Attachment a = new Attachment(h, is);
-		AttachmentItem item = retriever.createAttachmentItem(a, true);
+		AttachmentItem item = retriever.getAttachmentItem(a, true);
 		assertEquals(1, item.getWidth());
 		assertEquals(1, item.getHeight());
 		assertEquals(dimensions.minHeight, item.getThumbnailWidth());
 		assertEquals(dimensions.minHeight, item.getThumbnailHeight());
 		assertEquals("image/gif", item.getMimeType());
 		assertEquals("gif", item.getExtension());
-		assertEquals(AVAILABLE, item.getState());
+		assertFalse(item.hasError());
 	}
 
 	@Test
@@ -144,14 +143,14 @@ public class AttachmentRetrieverIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/gif");
 		InputStream is = getAssetInputStream("opti_png_afl.gif");
 		Attachment a = new Attachment(h, is);
-		AttachmentItem item = retriever.createAttachmentItem(a, true);
+		AttachmentItem item = retriever.getAttachmentItem(a, true);
 		assertEquals(32, item.getWidth());
 		assertEquals(32, item.getHeight());
 		assertEquals(dimensions.minHeight, item.getThumbnailWidth());
 		assertEquals(dimensions.minHeight, item.getThumbnailHeight());
 		assertEquals("image/gif", item.getMimeType());
 		assertEquals("gif", item.getExtension());
-		assertEquals(AVAILABLE, item.getState());
+		assertFalse(item.hasError());
 	}
 
 	@Test
@@ -159,8 +158,8 @@ public class AttachmentRetrieverIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/jpeg");
 		InputStream is = getAssetInputStream("libraw_error.jpg");
 		Attachment a = new Attachment(h, is);
-		AttachmentItem item = retriever.createAttachmentItem(a, true);
-		assertEquals(ERROR, item.getState());
+		AttachmentItem item = retriever.getAttachmentItem(a, true);
+		assertTrue(item.hasError());
 	}
 
 	@Test
@@ -168,14 +167,14 @@ public class AttachmentRetrieverIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/gif");
 		InputStream is = getAssetInputStream("animated.gif");
 		Attachment a = new Attachment(h, is);
-		AttachmentItem item = retriever.createAttachmentItem(a, true);
+		AttachmentItem item = retriever.getAttachmentItem(a, true);
 		assertEquals(65535, item.getWidth());
 		assertEquals(65535, item.getHeight());
 		assertEquals(dimensions.maxWidth, item.getThumbnailWidth());
 		assertEquals(dimensions.maxWidth, item.getThumbnailHeight());
 		assertEquals("image/gif", item.getMimeType());
 		assertEquals("gif", item.getExtension());
-		assertEquals(AVAILABLE, item.getState());
+		assertFalse(item.hasError());
 	}
 
 	@Test
@@ -183,14 +182,14 @@ public class AttachmentRetrieverIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/gif");
 		InputStream is = getAssetInputStream("animated2.gif");
 		Attachment a = new Attachment(h, is);
-		AttachmentItem item = retriever.createAttachmentItem(a, true);
+		AttachmentItem item = retriever.getAttachmentItem(a, true);
 		assertEquals(10000, item.getWidth());
 		assertEquals(10000, item.getHeight());
 		assertEquals(dimensions.maxWidth, item.getThumbnailWidth());
 		assertEquals(dimensions.maxWidth, item.getThumbnailHeight());
 		assertEquals("image/gif", item.getMimeType());
 		assertEquals("gif", item.getExtension());
-		assertEquals(AVAILABLE, item.getState());
+		assertFalse(item.hasError());
 	}
 
 	@Test
@@ -198,14 +197,14 @@ public class AttachmentRetrieverIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/gif");
 		InputStream is = getAssetInputStream("error_large.gif");
 		Attachment a = new Attachment(h, is);
-		AttachmentItem item = retriever.createAttachmentItem(a, true);
+		AttachmentItem item = retriever.getAttachmentItem(a, true);
 		assertEquals(16384, item.getWidth());
 		assertEquals(16384, item.getHeight());
 		assertEquals(dimensions.maxWidth, item.getThumbnailWidth());
 		assertEquals(dimensions.maxWidth, item.getThumbnailHeight());
 		assertEquals("image/gif", item.getMimeType());
 		assertEquals("gif", item.getExtension());
-		assertEquals(AVAILABLE, item.getState());
+		assertFalse(item.hasError());
 	}
 
 	@Test
@@ -213,14 +212,14 @@ public class AttachmentRetrieverIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/jpeg");
 		InputStream is = getAssetInputStream("error_high.jpg");
 		Attachment a = new Attachment(h, is);
-		AttachmentItem item = retriever.createAttachmentItem(a, true);
+		AttachmentItem item = retriever.getAttachmentItem(a, true);
 		assertEquals(1, item.getWidth());
 		assertEquals(10000, item.getHeight());
 		assertEquals(dimensions.minWidth, item.getThumbnailWidth());
 		assertEquals(dimensions.maxHeight, item.getThumbnailHeight());
 		assertEquals("image/jpeg", item.getMimeType());
 		assertJpgOrJpeg(item.getExtension());
-		assertEquals(AVAILABLE, item.getState());
+		assertFalse(item.hasError());
 	}
 
 	@Test
@@ -228,14 +227,14 @@ public class AttachmentRetrieverIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/jpeg");
 		InputStream is = getAssetInputStream("error_wide.jpg");
 		Attachment a = new Attachment(h, is);
-		AttachmentItem item = retriever.createAttachmentItem(a, true);
+		AttachmentItem item = retriever.getAttachmentItem(a, true);
 		assertEquals(1920, item.getWidth());
 		assertEquals(1, item.getHeight());
 		assertEquals(dimensions.maxWidth, item.getThumbnailWidth());
 		assertEquals(dimensions.minHeight, item.getThumbnailHeight());
 		assertEquals("image/jpeg", item.getMimeType());
 		assertJpgOrJpeg(item.getExtension());
-		assertEquals(AVAILABLE, item.getState());
+		assertFalse(item.hasError());
 	}
 
 	private InputStream getAssetInputStream(String name) throws Exception {

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

@@ -36,6 +36,7 @@ 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.viewmodel.ViewModelModule;
 import org.briarproject.briar.api.android.AndroidNotificationManager;
 import org.briarproject.briar.api.android.DozeWatchdog;
@@ -64,7 +65,11 @@ import static org.briarproject.bramble.api.reporting.ReportingConstants.DEV_ONIO
 import static org.briarproject.bramble.api.reporting.ReportingConstants.DEV_PUBLIC_KEY_HEX;
 import static org.briarproject.briar.android.TestingConstants.IS_DEBUG_BUILD;
 
-@Module(includes = {ContactExchangeModule.class, ViewModelModule.class})
+@Module(includes = {
+		NavDrawerModule.class,
+		ContactExchangeModule.class,
+		ViewModelModule.class
+})
 public class AppModule {
 
 	static class EagerSingletons {

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

@@ -10,8 +10,6 @@ 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.login.ChangePasswordControllerImpl;
-import org.briarproject.briar.android.navdrawer.NavDrawerController;
-import org.briarproject.briar.android.navdrawer.NavDrawerControllerImpl;
 
 import dagger.Module;
 import dagger.Provides;
@@ -67,14 +65,6 @@ public class ActivityModule {
 		return dbController;
 	}
 
-	@ActivityScope
-	@Provides
-	NavDrawerController provideNavDrawerController(
-			NavDrawerControllerImpl navDrawerController) {
-		activity.addLifecycleController(navDrawerController);
-		return navDrawerController;
-	}
-
 	@ActivityScope
 	@Provides
 	BriarServiceConnection provideBriarServiceConnection() {

briar-android/src/main/java/org/briarproject/briar/android/attachment/AttachmentCreatorImpl.java

@@ -34,7 +34,6 @@ import androidx.lifecycle.MutableLiveData;
 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.attachment.AttachmentItem.State.ERROR;
 import static org.briarproject.briar.android.util.UiUtils.observeForeverOnce;
 import static org.briarproject.briar.api.messaging.MessagingConstants.MAX_IMAGE_SIZE;
 
@@ -110,8 +109,8 @@ class AttachmentCreatorImpl implements AttachmentCreator {
 		// get and cache AttachmentItem for ImagePreview
 		try {
 			Attachment a = retriever.getMessageAttachment(h);
-			AttachmentItem item = retriever.createAttachmentItem(a, needsSize);
-			if (item.getState() == ERROR) throw new IOException();
+			AttachmentItem item = retriever.getAttachmentItem(a, needsSize);
+			if (item.hasError()) throw new IOException();
 			AttachmentItemResult itemResult =
 					new AttachmentItemResult(uri, item);
 			itemResults.add(itemResult);
@@ -168,6 +167,13 @@ class AttachmentCreatorImpl implements AttachmentCreator {
 	@Override
 	@UiThread
 	public void onAttachmentsSent(MessageId id) {
+		List<AttachmentItem> items = new ArrayList<>(itemResults.size());
+		for (AttachmentItemResult itemResult : itemResults) {
+			// check if we are trying to send attachment items with errors
+			if (itemResult.getItem() == null) throw new IllegalStateException();
+			items.add(itemResult.getItem());
+		}
+		retriever.cachePut(id, items);
 		resetState();
 	}
 

briar-android/src/main/java/org/briarproject/briar/android/attachment/AttachmentItem.java

@@ -7,33 +7,24 @@ import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.briar.api.messaging.AttachmentHeader;
 
+import java.util.concurrent.atomic.AtomicLong;
+
 import javax.annotation.concurrent.Immutable;
 
 import androidx.annotation.Nullable;
 
-import static java.lang.System.arraycopy;
 import static java.util.Objects.requireNonNull;
-import static org.briarproject.bramble.util.StringUtils.toHexString;
-import static org.briarproject.briar.android.attachment.AttachmentItem.State.LOADING;
-import static org.briarproject.briar.android.attachment.AttachmentItem.State.MISSING;
 
 @Immutable
 @NotNullByDefault
 public class AttachmentItem implements Parcelable {
 
-	public enum State {
-		LOADING, MISSING, AVAILABLE, ERROR;
-
-		public boolean isFinal() {
-			return this == AVAILABLE || this == ERROR;
-		}
-	}
-
 	private final AttachmentHeader header;
 	private final int width, height;
 	private final String extension;
 	private final int thumbnailWidth, thumbnailHeight;
-	private final State state;
+	private final boolean hasError;
+	private final long instanceId;
 
 	public static final Creator<AttachmentItem> CREATOR =
 			new Creator<AttachmentItem>() {
@@ -48,33 +39,19 @@ public class AttachmentItem implements Parcelable {
 				}
 			};
 
+	private static final AtomicLong NEXT_INSTANCE_ID = new AtomicLong(0);
+
 	AttachmentItem(AttachmentHeader header, int width, int height,
 			String extension, int thumbnailWidth, int thumbnailHeight,
-			State state) {
+			boolean hasError) {
 		this.header = header;
 		this.width = width;
 		this.height = height;
 		this.extension = extension;
 		this.thumbnailWidth = thumbnailWidth;
 		this.thumbnailHeight = thumbnailHeight;
-		this.state = state;
-	}
-
-	/**
-	 * Use only for {@link State MISSING} or {@link State LOADING} items.
-	 */
-	AttachmentItem(AttachmentHeader header, int width, int height,
-			State state) {
-		this(header, width, height, "", width, height, state);
-		if (state != MISSING && state != LOADING)
-			throw new IllegalArgumentException();
-	}
-
-	/**
-	 * Use when the item does not need a size.
-	 */
-	AttachmentItem(AttachmentHeader header, String extension, State state) {
-		this(header, 0, 0, extension, 0, 0, state);
+		this.hasError = hasError;
+		instanceId = NEXT_INSTANCE_ID.getAndIncrement();
 	}
 
 	protected AttachmentItem(Parcel in) {
@@ -87,7 +64,8 @@ public class AttachmentItem implements Parcelable {
 		extension = requireNonNull(in.readString());
 		thumbnailWidth = in.readInt();
 		thumbnailHeight = in.readInt();
-		state = State.valueOf(requireNonNull(in.readString()));
+		hasError = in.readByte() != 0;
+		instanceId = in.readLong();
 		header = new AttachmentHeader(messageId, mimeType);
 	}
 
@@ -123,20 +101,12 @@ public class AttachmentItem implements Parcelable {
 		return thumbnailHeight;
 	}
 
-	public State getState() {
-		return state;
+	public boolean hasError() {
+		return hasError;
 	}
 
-	public String getTransitionName(MessageId conversationItemId) {
-		int len = MessageId.LENGTH;
-		byte[] instanceId = new byte[len * 2];
-		arraycopy(header.getMessageId().getBytes(), 0, instanceId, 0, len);
-		arraycopy(conversationItemId.getBytes(), 0, instanceId, len, len);
-		return toHexString(instanceId);
-	}
-
-	boolean hasSize() {
-		return width != 0 && height != 0;
+	public String getTransitionName() {
+		return String.valueOf(instanceId);
 	}
 
 	@Override
@@ -153,15 +123,14 @@ public class AttachmentItem implements Parcelable {
 		dest.writeString(extension);
 		dest.writeInt(thumbnailWidth);
 		dest.writeInt(thumbnailHeight);
-		dest.writeString(state.name());
+		dest.writeByte((byte) (hasError ? 1 : 0));
+		dest.writeLong(instanceId);
 	}
 
 	@Override
 	public boolean equals(@Nullable Object o) {
 		return o instanceof AttachmentItem &&
-				header.getMessageId().equals(
-						((AttachmentItem) o).header.getMessageId()
-				);
+				instanceId == ((AttachmentItem) o).instanceId;
 	}
 
 }

briar-android/src/main/java/org/briarproject/briar/android/attachment/AttachmentRetriever.java

@@ -1,56 +1,29 @@
 package org.briarproject.briar.android.attachment;
 
-import org.briarproject.bramble.api.db.DatabaseExecutor;
 import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.briar.api.messaging.Attachment;
 import org.briarproject.briar.api.messaging.AttachmentHeader;
-import org.briarproject.briar.api.messaging.PrivateMessageHeader;
-import org.briarproject.briar.api.messaging.event.AttachmentReceivedEvent;
 
 import java.io.InputStream;
 import java.util.List;
 
-import androidx.lifecycle.LiveData;
-
+import androidx.annotation.Nullable;
 
 @NotNullByDefault
 public interface AttachmentRetriever {
 
-	@DatabaseExecutor
+	void cachePut(MessageId messageId, List<AttachmentItem> attachments);
+
+	@Nullable
+	List<AttachmentItem> cacheGet(MessageId messageId);
+
 	Attachment getMessageAttachment(AttachmentHeader h) throws DbException;
 
-	/**
-	 * Returns a list of observable {@link LiveData}
-	 * that get updated as the state of their {@link AttachmentItem}s changes.
-	 */
-	List<LiveData<AttachmentItem>> getAttachmentItems(
-			PrivateMessageHeader messageHeader);
-
-	/**
-	 * Retrieves item size and adds the item to the cache, if available.
-	 * <p>
-	 * Use this to eagerly load the attachment size before it gets displayed.
-	 * This is needed for messages containing a single attachment.
-	 * Messages with more than one attachment use a standard size.
-	 */
-	@DatabaseExecutor
-	void cacheAttachmentItemWithSize(MessageId conversationMessageId,
-			AttachmentHeader h) throws DbException;
-
 	/**
 	 * Creates an {@link AttachmentItem} from the {@link Attachment}'s
 	 * {@link InputStream} which will be closed when this method returns.
 	 */
-	AttachmentItem createAttachmentItem(Attachment a, boolean needsSize);
-
-	/**
-	 * Loads an {@link AttachmentItem}
-	 * that arrived via an {@link AttachmentReceivedEvent}
-	 * and notifies the associated {@link LiveData}.
-	 */
-	@DatabaseExecutor
-	void loadAttachmentItem(MessageId attachmentId);
-
+	AttachmentItem getAttachmentItem(Attachment a, boolean needsSize);
 }

briar-android/src/main/java/org/briarproject/briar/android/attachment/AttachmentRetrieverImpl.java

@@ -1,39 +1,25 @@
 package org.briarproject.briar.android.attachment;
 
-import org.briarproject.bramble.api.db.DatabaseExecutor;
 import org.briarproject.bramble.api.db.DbException;
-import org.briarproject.bramble.api.db.NoSuchMessageException;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.sync.MessageId;
-import org.briarproject.briar.android.attachment.AttachmentItem.State;
 import org.briarproject.briar.api.messaging.Attachment;
 import org.briarproject.briar.api.messaging.AttachmentHeader;
 import org.briarproject.briar.api.messaging.MessagingManager;
-import org.briarproject.briar.api.messaging.PrivateMessageHeader;
 
 import java.io.BufferedInputStream;
 import java.io.InputStream;
-import java.util.ArrayList;
 import java.util.List;
 import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
-import java.util.concurrent.Executor;
 import java.util.logging.Logger;
 
 import javax.inject.Inject;
 
-import androidx.lifecycle.LiveData;
-import androidx.lifecycle.MutableLiveData;
+import androidx.annotation.Nullable;
 
-import static java.util.Objects.requireNonNull;
 import static java.util.logging.Level.WARNING;
 import static java.util.logging.Logger.getLogger;
-import static org.briarproject.bramble.util.IoUtils.tryToClose;
-import static org.briarproject.bramble.util.LogUtils.logException;
-import static org.briarproject.briar.android.attachment.AttachmentItem.State.AVAILABLE;
-import static org.briarproject.briar.android.attachment.AttachmentItem.State.ERROR;
-import static org.briarproject.briar.android.attachment.AttachmentItem.State.LOADING;
-import static org.briarproject.briar.android.attachment.AttachmentItem.State.MISSING;
 
 @NotNullByDefault
 class AttachmentRetrieverImpl implements AttachmentRetriever {
@@ -41,8 +27,6 @@ class AttachmentRetrieverImpl implements AttachmentRetriever {
 	private static final Logger LOG =
 			getLogger(AttachmentRetrieverImpl.class.getName());
 
-	@DatabaseExecutor
-	private final Executor dbExecutor;
 	private final MessagingManager messagingManager;
 	private final ImageHelper imageHelper;
 	private final ImageSizeCalculator imageSizeCalculator;
@@ -50,17 +34,13 @@ class AttachmentRetrieverImpl implements AttachmentRetriever {
 	private final int minWidth, maxWidth;
 	private final int minHeight, maxHeight;
 
-	private final Map<MessageId, MutableLiveData<AttachmentItem>>
-			itemsWithSize = new ConcurrentHashMap<>();
-	private final Map<MessageId, MutableLiveData<AttachmentItem>>
-			itemsWithoutSize = new ConcurrentHashMap<>();
+	private final Map<MessageId, List<AttachmentItem>> attachmentCache =
+			new ConcurrentHashMap<>();
 
 	@Inject
-	AttachmentRetrieverImpl(@DatabaseExecutor Executor dbExecutor,
-			MessagingManager messagingManager,
+	AttachmentRetrieverImpl(MessagingManager messagingManager,
 			AttachmentDimensions dimensions, ImageHelper imageHelper,
 			ImageSizeCalculator imageSizeCalculator) {
-		this.dbExecutor = dbExecutor;
 		this.messagingManager = messagingManager;
 		this.imageHelper = imageHelper;
 		this.imageSizeCalculator = imageSizeCalculator;
@@ -72,130 +52,40 @@ class AttachmentRetrieverImpl implements AttachmentRetriever {
 	}
 
 	@Override
-	@DatabaseExecutor
+	public void cachePut(MessageId messageId,
+			List<AttachmentItem> attachments) {
+		attachmentCache.put(messageId, attachments);
+	}
+
+	@Override
+	@Nullable
+	public List<AttachmentItem> cacheGet(MessageId messageId) {
+		return attachmentCache.get(messageId);
+	}
+
+	@Override
 	public Attachment getMessageAttachment(AttachmentHeader h)
 			throws DbException {
 		return messagingManager.getAttachment(h);
 	}
 
 	@Override
-	public List<LiveData<AttachmentItem>> getAttachmentItems(
-			PrivateMessageHeader messageHeader) {
-		List<AttachmentHeader> headers = messageHeader.getAttachmentHeaders();
-		List<LiveData<AttachmentItem>> items = new ArrayList<>(headers.size());
-		boolean needsSize = headers.size() == 1;
-		for (AttachmentHeader h : headers) {
-			// try cache for existing item live data
-			MutableLiveData<AttachmentItem> liveData;
-			if (needsSize) liveData = itemsWithSize.get(h.getMessageId());
-			else {
-				// try items with size first, as they work as well
-				liveData = itemsWithSize.get(h.getMessageId());
-				if (liveData == null)
-					liveData = itemsWithoutSize.get(h.getMessageId());
-			}
-
-			// create new live data with LOADING item if cache miss
-			if (liveData == null) {
-				AttachmentItem item = new AttachmentItem(h,
-						defaultSize, defaultSize, LOADING);
-				final MutableLiveData<AttachmentItem> finalLiveData =
-						new MutableLiveData<>(item);
-				// kick-off loading of attachment, will post to live data
-				dbExecutor.execute(
-						() -> loadAttachmentItem(h, needsSize, finalLiveData));
-				// add new LiveData to cache
-				liveData = finalLiveData;
-				if (needsSize) itemsWithSize.put(h.getMessageId(), liveData);
-				else itemsWithoutSize.put(h.getMessageId(), liveData);
-			}
-			items.add(liveData);
-		}
-		return items;
-	}
-
-	@Override
-	@DatabaseExecutor
-	public void cacheAttachmentItemWithSize(MessageId conversationMessageId,
-			AttachmentHeader h) throws DbException {
-		try {
-			Attachment a = messagingManager.getAttachment(h);
-			AttachmentItem item = createAttachmentItem(a, true);
-			MutableLiveData<AttachmentItem> liveData =
-					new MutableLiveData<>(item);
-			itemsWithSize.put(h.getMessageId(), liveData);
-		} catch (NoSuchMessageException e) {
-			LOG.info("Attachment not received yet");
-		}
-	}
-
-	@Override
-	@DatabaseExecutor
-	public void loadAttachmentItem(MessageId attachmentId) {
-		// try to find LiveData for attachment in both caches
-		MutableLiveData<AttachmentItem> liveData;
-		boolean needsSize = true;
-		liveData = itemsWithSize.get(attachmentId);
-		if (liveData == null) {
-			needsSize = false;
-			liveData = itemsWithoutSize.get(attachmentId);
-		}
-
-		// If no LiveData for the attachment exists,
-		// its message did not yet arrive and we can ignore it for now.
-		if (liveData == null) return;
-
-		// actually load the attachment item
-		AttachmentHeader h = requireNonNull(liveData.getValue()).getHeader();
-		loadAttachmentItem(h, needsSize, liveData);
-	}
-
-	/**
-	 * Loads an {@link AttachmentItem} from the database
-	 * and notifies the given {@link LiveData}.
-	 */
-	@DatabaseExecutor
-	private void loadAttachmentItem(AttachmentHeader h, boolean needsSize,
-			MutableLiveData<AttachmentItem> liveData) {
-		Attachment a;
-		AttachmentItem item;
-		try {
-			a = messagingManager.getAttachment(h);
-			item = createAttachmentItem(a, needsSize);
-		} catch (NoSuchMessageException e) {
-			LOG.info("Attachment not received yet");
-			item = new AttachmentItem(h, defaultSize, defaultSize, MISSING);
-		} catch (DbException e) {
-			logException(LOG, WARNING, e);
-			item = new AttachmentItem(h, "", ERROR);
-		}
-		liveData.postValue(item);
-	}
-
-	@Override
-	public AttachmentItem createAttachmentItem(Attachment a,
-			boolean needsSize) {
-		AttachmentItem item;
+	public AttachmentItem getAttachmentItem(Attachment a, boolean needsSize) {
 		AttachmentHeader h = a.getHeader();
-		if (needsSize) {
-			InputStream is = new BufferedInputStream(a.getStream());
-			Size size = imageSizeCalculator.getSize(is, h.getContentType());
-			tryToClose(is, LOG, WARNING);
-			item = createAttachmentItem(h, size);
-		} else {
+		if (!needsSize) {
 			String extension =
 					imageHelper.getExtensionFromMimeType(h.getContentType());
-			State state = AVAILABLE;
+			boolean hasError = false;
 			if (extension == null) {
 				extension = "";
-				state = ERROR;
+				hasError = true;
 			}
-			item = new AttachmentItem(h, extension, state);
+			return new AttachmentItem(h, 0, 0, extension, 0, 0, hasError);
 		}
-		return item;
-	}
 
-	private AttachmentItem createAttachmentItem(AttachmentHeader h, Size size) {
+		InputStream is = new BufferedInputStream(a.getStream());
+		Size size = imageSizeCalculator.getSize(is, h.getContentType());
+
 		// calculate thumbnail size
 		Size thumbnailSize = new Size(defaultSize, defaultSize, size.mimeType);
 		if (!size.error) {
@@ -214,9 +104,8 @@ class AttachmentRetrieverImpl implements AttachmentRetriever {
 			hasError = true;
 		}
 		if (extension == null) extension = "";
-		State state = hasError ? ERROR : AVAILABLE;
-		return new AttachmentItem(h, size.width, size.height,
-				extension, thumbnailSize.width, thumbnailSize.height, state);
+		return new AttachmentItem(h, size.width, size.height, extension,
+				thumbnailSize.width, thumbnailSize.height, hasError);
 	}
 
 	private Size getThumbnailSize(int width, int height, String mimeType) {

briar-android/src/main/java/org/briarproject/briar/android/attachment/UnavailableItem.java

@@ -1,36 +0,0 @@
-package org.briarproject.briar.android.attachment;
-
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.sync.MessageId;
-import org.briarproject.briar.api.messaging.AttachmentHeader;
-
-import javax.annotation.concurrent.Immutable;
-
-@Immutable
-@NotNullByDefault
-class UnavailableItem {
-
-	private final MessageId conversationMessageId;
-	private final AttachmentHeader header;
-	private final boolean needsSize;
-
-	UnavailableItem(MessageId conversationMessageId,
-			AttachmentHeader header, boolean needsSize) {
-		this.conversationMessageId = conversationMessageId;
-		this.header = header;
-		this.needsSize = needsSize;
-	}
-
-	MessageId getConversationMessageId() {
-		return conversationMessageId;
-	}
-
-	AttachmentHeader getHeader() {
-		return header;
-	}
-
-	boolean needsSize() {
-		return needsSize;
-	}
-
-}

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

@@ -9,7 +9,6 @@ import org.briarproject.briar.android.controller.handler.ResultExceptionHandler;
 
 import java.util.Collection;
 
-import androidx.annotation.Nullable;
 import androidx.annotation.UiThread;
 
 @NotNullByDefault
@@ -18,7 +17,10 @@ public interface BlogController extends BaseController {
 	void setGroupId(GroupId g);
 
 	@UiThread
-	void setBlogSharingListener(@Nullable BlogSharingListener listener);
+	void setBlogSharingListener(BlogSharingListener listener);
+
+	@UiThread
+	void unsetBlogSharingListener(BlogSharingListener listener);
 
 	void loadBlogPosts(
 			ResultExceptionHandler<Collection<BlogPostItem>, DbException> handler);

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

@@ -96,10 +96,15 @@ class BlogControllerImpl extends BaseControllerImpl
 	}
 
 	@Override
-	public void setBlogSharingListener(@Nullable BlogSharingListener listener) {
+	public void setBlogSharingListener(BlogSharingListener listener) {
 		this.listener = listener;
 	}
 
+	@Override
+	public void unsetBlogSharingListener(BlogSharingListener listener) {
+		if (this.listener == listener) this.listener = null;
+	}
+
 	@Override
 	public void eventOccurred(Event e) {
 		if (groupId == null || listener == null)

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

@@ -141,7 +141,8 @@ public class BlogFragment extends BaseFragment
 	@Override
 	public void onDestroy() {
 		super.onDestroy();
-		blogController.setBlogSharingListener(null);
+		blogController.unsetBlogSharingListener(this);
+		sharingController.unsetSharingListener(this);
 	}
 
 	@Override

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

@@ -7,7 +7,6 @@ import org.briarproject.briar.api.blog.Blog;
 
 import java.util.Collection;
 
-import androidx.annotation.Nullable;
 import androidx.annotation.UiThread;
 
 @NotNullByDefault
@@ -19,7 +18,10 @@ public interface FeedController extends BaseController {
 	void loadPersonalBlog(ResultExceptionHandler<Blog, DbException> handler);
 
 	@UiThread
-	void setFeedListener(@Nullable FeedListener listener);
+	void setFeedListener(FeedListener listener);
+
+	@UiThread
+	void unsetFeedListener(FeedListener listener);
 
 	@NotNullByDefault
 	interface FeedListener extends BlogListener {

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

@@ -69,10 +69,15 @@ class FeedControllerImpl extends BaseControllerImpl implements FeedController {
 	}
 
 	@Override
-	public void setFeedListener(@Nullable FeedListener listener) {
+	public void setFeedListener(FeedListener listener) {
 		this.listener = listener;
 	}
 
+	@Override
+	public void unsetFeedListener(FeedListener listener) {
+		if (this.listener == listener) this.listener = null;
+	}
+
 	@Override
 	public void eventOccurred(Event e) {
 		if (listener == null) throw new IllegalStateException();

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

@@ -134,7 +134,7 @@ public class FeedFragment extends BaseFragment implements
 	@Override
 	public void onDestroy() {
 		super.onDestroy();
-		feedController.setFeedListener(null);
+		feedController.unsetFeedListener(this);
 	}
 
 	@Override

briar-android/src/main/java/org/briarproject/briar/android/contact/ContactListFragment.java

@@ -61,7 +61,7 @@ import io.github.kobakei.materialfabspeeddial.FabSpeedDial.OnMenuItemClickListen
 import static android.os.Build.VERSION.SDK_INT;
 import static androidx.core.app.ActivityOptionsCompat.makeSceneTransitionAnimation;
 import static androidx.core.view.ViewCompat.getTransitionName;
-import static com.google.android.material.snackbar.Snackbar.LENGTH_INDEFINITE;
+import static com.google.android.material.snackbar.BaseTransientBottomBar.LENGTH_INDEFINITE;
 import static java.util.Objects.requireNonNull;
 import static java.util.logging.Level.WARNING;
 import static org.briarproject.bramble.util.LogUtils.logDuration;
@@ -87,7 +87,12 @@ public class ContactListFragment extends BaseFragment implements EventListener,
 
 	private ContactListAdapter adapter;
 	private BriarRecyclerView list;
-	private Snackbar snackbar;
+	/**
+	 * The Snackbar is non-null when shown and null otherwise.
+	 * Use {@link #showSnackBar()} and {@link #dismissSnackBar()} to interact.
+	 */
+	@Nullable
+	private Snackbar snackbar = null;
 
 	// Fields that are accessed from background threads must be volatile
 	@Inject
@@ -163,13 +168,6 @@ public class ContactListFragment extends BaseFragment implements EventListener,
 		list.setEmptyText(getString(R.string.no_contacts));
 		list.setEmptyAction(getString(R.string.no_contacts_action));
 
-		snackbar = new BriarSnackbarBuilder()
-				.setAction(R.string.show, v ->
-						startActivity(new Intent(getContext(),
-								PendingContactListActivity.class)))
-				.make(contentView, R.string.pending_contact_requests_snackbar,
-						LENGTH_INDEFINITE);
-
 		return contentView;
 	}
 
@@ -203,9 +201,9 @@ public class ContactListFragment extends BaseFragment implements EventListener,
 		listener.runOnDbThread(() -> {
 			try {
 				if (contactManager.getPendingContacts().isEmpty()) {
-					runOnUiThreadUnlessDestroyed(() -> snackbar.dismiss());
+					runOnUiThreadUnlessDestroyed(this::dismissSnackBar);
 				} else {
-					runOnUiThreadUnlessDestroyed(() -> snackbar.show());
+					runOnUiThreadUnlessDestroyed(this::showSnackBar);
 				}
 			} catch (DbException e) {
 				logException(LOG, WARNING, e);
@@ -220,6 +218,7 @@ public class ContactListFragment extends BaseFragment implements EventListener,
 		adapter.clear();
 		list.showProgressBar();
 		list.stopPeriodicUpdate();
+		dismissSnackBar();
 	}
 
 	private void loadContacts() {
@@ -315,4 +314,27 @@ public class ContactListFragment extends BaseFragment implements EventListener,
 		}
 	}
 
+	@UiThread
+	private void showSnackBar() {
+		if (snackbar != null) return;
+		View v = requireNonNull(getView());
+		int stringRes = R.string.pending_contact_requests_snackbar;
+		snackbar = new BriarSnackbarBuilder()
+				.setAction(R.string.show, view -> showPendingContactList())
+				.make(v, stringRes, LENGTH_INDEFINITE);
+		snackbar.show();
+	}
+
+	@UiThread
+	private void dismissSnackBar() {
+		if (snackbar == null) return;
+		snackbar.dismiss();
+		snackbar = null;
+	}
+
+	private void showPendingContactList() {
+		Intent i = new Intent(getContext(), PendingContactListActivity.class);
+		startActivity(i);
+	}
+
 }

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

@@ -3,7 +3,6 @@ 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;
@@ -38,12 +37,10 @@ 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
@@ -199,9 +196,7 @@ public class NicknameFragment extends BaseFragment {
 	private void showWarningDialog(String name1, String name2) {
 		Context ctx = requireContext();
 		Builder b = new Builder(ctx, R.style.BriarDialogTheme);
-		Drawable icon = getDrawable(ctx, R.drawable.alerts_and_states_error);
-		setTint(requireNonNull(icon), getColor(ctx, R.color.color_primary));
-		b.setIcon(icon);
+		b.setIcon(getDialogIcon(ctx, R.drawable.alerts_and_states_error));
 		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/contact/add/remote/PendingContactListViewModel.java

@@ -92,7 +92,7 @@ public class PendingContactListViewModel extends AndroidViewModel
 				Collection<Pair<PendingContact, PendingContactState>> pairs =
 						contactManager.getPendingContacts();
 				List<PendingContactItem> items = new ArrayList<>(pairs.size());
-				boolean online = items.isEmpty();
+				boolean online = pairs.isEmpty();
 				for (Pair<PendingContact, PendingContactState> pair : pairs) {
 					PendingContact p = pair.getFirst();
 					PendingContactState state = pair.getSecond();

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

@@ -54,8 +54,6 @@ class PendingContactViewHolder extends ViewHolder {
 				status.setText(R.string.waiting_for_contact_to_come_online);
 				break;
 			case OFFLINE:
-				color = ContextCompat
-						.getColor(status.getContext(), R.color.briar_yellow);
 				status.setText("");
 				break;
 			case CONNECTING:

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

@@ -16,6 +16,12 @@ public interface SharingController {
 	@UiThread
 	void setSharingListener(SharingListener listener);
 
+	/**
+	 * Unsets the listener.
+	 */
+	@UiThread
+	void unsetSharingListener(SharingListener listener);
+
 	/**
 	 * Call this when your lifecycle starts,
 	 * so the listener will be called when information changes.

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

@@ -43,6 +43,11 @@ public class SharingControllerImpl implements SharingController, EventListener {
 		this.listener = listener;
 	}
 
+	@Override
+	public void unsetSharingListener(SharingListener listener) {
+		if (this.listener == listener) this.listener = null;
+	}
+
 	@Override
 	public void onStart() {
 		eventBus.addListener(this);

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

@@ -27,6 +27,7 @@ import org.briarproject.bramble.api.contact.event.ContactRemovedEvent;
 import org.briarproject.bramble.api.db.DatabaseExecutor;
 import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.db.NoSuchContactException;
+import org.briarproject.bramble.api.db.NoSuchMessageException;
 import org.briarproject.bramble.api.event.Event;
 import org.briarproject.bramble.api.event.EventBus;
 import org.briarproject.bramble.api.event.EventListener;
@@ -64,13 +65,13 @@ import org.briarproject.briar.api.client.ProtocolStateException;
 import org.briarproject.briar.api.client.SessionId;
 import org.briarproject.briar.api.conversation.ConversationManager;
 import org.briarproject.briar.api.conversation.ConversationMessageHeader;
-import org.briarproject.briar.api.conversation.ConversationMessageVisitor;
 import org.briarproject.briar.api.conversation.ConversationRequest;
 import org.briarproject.briar.api.conversation.ConversationResponse;
 import org.briarproject.briar.api.conversation.DeletionResult;
 import org.briarproject.briar.api.conversation.event.ConversationMessageReceivedEvent;
 import org.briarproject.briar.api.forum.ForumSharingManager;
 import org.briarproject.briar.api.introduction.IntroductionManager;
+import org.briarproject.briar.api.messaging.Attachment;
 import org.briarproject.briar.api.messaging.AttachmentHeader;
 import org.briarproject.briar.api.messaging.MessagingManager;
 import org.briarproject.briar.api.messaging.PrivateMessageHeader;
@@ -96,7 +97,6 @@ import androidx.appcompat.widget.Toolbar;
 import androidx.core.app.ActivityCompat;
 import androidx.core.app.ActivityOptionsCompat;
 import androidx.core.content.ContextCompat;
-import androidx.lifecycle.LiveData;
 import androidx.lifecycle.Observer;
 import androidx.lifecycle.ViewModelProvider;
 import androidx.lifecycle.ViewModelProviders;
@@ -118,6 +118,8 @@ import static androidx.core.app.ActivityOptionsCompat.makeSceneTransitionAnimati
 import static androidx.core.view.ViewCompat.setTransitionName;
 import static androidx.lifecycle.Lifecycle.State.STARTED;
 import static androidx.recyclerview.widget.SortedList.INVALID_POSITION;
+import static java.util.Collections.emptyList;
+import static java.util.Collections.singletonList;
 import static java.util.Collections.sort;
 import static java.util.Objects.requireNonNull;
 import static java.util.logging.Level.INFO;
@@ -134,7 +136,6 @@ import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_INTRO
 import static org.briarproject.briar.android.conversation.ImageActivity.ATTACHMENTS;
 import static org.briarproject.briar.android.conversation.ImageActivity.ATTACHMENT_POSITION;
 import static org.briarproject.briar.android.conversation.ImageActivity.DATE;
-import static org.briarproject.briar.android.conversation.ImageActivity.ITEM_ID;
 import static org.briarproject.briar.android.conversation.ImageActivity.NAME;
 import static org.briarproject.briar.android.util.UiUtils.getAvatarTransitionName;
 import static org.briarproject.briar.android.util.UiUtils.getBulbTransitionName;
@@ -184,6 +185,8 @@ public class ConversationActivity extends BriarActivity
 	volatile GroupInvitationManager groupInvitationManager;
 
 	private final Map<MessageId, String> textCache = new ConcurrentHashMap<>();
+	private final Map<MessageId, PrivateMessageHeader> missingAttachments =
+			new ConcurrentHashMap<>();
 	private final Observer<String> contactNameObserver = name -> {
 		requireNonNull(name);
 		loadMessages();
@@ -261,7 +264,6 @@ public class ConversationActivity extends BriarActivity
 		adapter = new ConversationAdapter(this, this);
 		list = findViewById(R.id.conversationView);
 		layoutManager = new LinearLayoutManager(this);
-		layoutManager.setStackFromEnd(true);
 		list.setLayoutManager(layoutManager);
 		list.setAdapter(adapter);
 		list.setEmptyText(getString(R.string.no_private_messages));
@@ -538,7 +540,6 @@ public class ConversationActivity extends BriarActivity
 		});
 	}
 
-	@DatabaseExecutor
 	private void eagerlyLoadMessageSize(PrivateMessageHeader h) {
 		try {
 			MessageId id = h.getId();
@@ -555,11 +556,21 @@ public class ConversationActivity extends BriarActivity
 			// images we use a grid so the size is fixed
 			List<AttachmentHeader> headers = h.getAttachmentHeaders();
 			if (headers.size() == 1) {
-				LOG.info("Eagerly loading image size for latest message");
-				AttachmentHeader header = headers.get(0);
-				// get the item to retrieve its size
-				attachmentRetriever
-						.cacheAttachmentItemWithSize(h.getId(), header);
+				List<AttachmentItem> items = attachmentRetriever.cacheGet(id);
+				if (items == null) {
+					LOG.info("Eagerly loading image size for latest message");
+					AttachmentHeader header = headers.get(0);
+					try {
+						Attachment a = attachmentRetriever
+								.getMessageAttachment(header);
+						AttachmentItem item =
+								attachmentRetriever.getAttachmentItem(a, true);
+						attachmentRetriever.cachePut(id, singletonList(item));
+					} catch (NoSuchMessageException e) {
+						LOG.info("Attachment not received yet");
+						missingAttachments.put(header.getMessageId(), h);
+					}
+				}
 			}
 		} catch (DbException e) {
 			logException(LOG, WARNING, e);
@@ -640,12 +651,44 @@ public class ConversationActivity extends BriarActivity
 				&& adapter.isScrolledToBottom(layoutManager);
 	}
 
-	private void updateMessageAttachment(MessageId m, AttachmentItem item) {
+	private void loadMessageAttachments(PrivateMessageHeader h) {
+		// TODO: Use placeholders for missing/invalid attachments
+		runOnDbThread(() -> {
+			try {
+				// TODO move getting the items off to IoExecutor, if size == 1
+				List<AttachmentHeader> headers = h.getAttachmentHeaders();
+				boolean needsSize = headers.size() == 1;
+				List<AttachmentItem> items = new ArrayList<>(headers.size());
+				for (AttachmentHeader header : headers) {
+					try {
+						Attachment a = attachmentRetriever
+								.getMessageAttachment(header);
+						AttachmentItem item = attachmentRetriever
+								.getAttachmentItem(a, needsSize);
+						items.add(item);
+					} catch (NoSuchMessageException e) {
+						LOG.info("Attachment not received yet");
+						missingAttachments.put(header.getMessageId(), h);
+						return;
+					}
+				}
+				// Don't cache items unless all are present and valid
+				attachmentRetriever.cachePut(h.getId(), items);
+				displayMessageAttachments(h.getId(), items);
+			} catch (DbException e) {
+				logException(LOG, WARNING, e);
+			}
+		});
+	}
+
+	private void displayMessageAttachments(MessageId m,
+			List<AttachmentItem> items) {
 		runOnUiThreadUnlessDestroyed(() -> {
 			Pair<Integer, ConversationMessageItem> pair =
 					adapter.getMessageItem(m);
-			if (pair != null && pair.getSecond().updateAttachments(item)) {
+			if (pair != null) {
 				boolean scroll = shouldScrollWhenUpdatingMessage();
+				pair.getSecond().setAttachments(items);
 				adapter.notifyItemChanged(pair.getFirst());
 				if (scroll) scrollToBottom();
 			}
@@ -722,8 +765,11 @@ public class ConversationActivity extends BriarActivity
 
 	@UiThread
 	private void onAttachmentReceived(MessageId attachmentId) {
-		runOnDbThread(
-				() -> attachmentRetriever.loadAttachmentItem(attachmentId));
+		PrivateMessageHeader h = missingAttachments.remove(attachmentId);
+		if (h != null) {
+			LOG.info("Missing attachment received");
+			loadMessageAttachments(h);
+		}
 	}
 
 	@UiThread
@@ -734,7 +780,7 @@ public class ConversationActivity extends BriarActivity
 			observeOnce(viewModel.getContactDisplayName(), this,
 					name -> addConversationItem(h.accept(visitor)));
 		} else {
-			// visitor also loads message text and attachments (if existing)
+			// visitor also loads message text (if existing)
 			addConversationItem(h.accept(visitor));
 		}
 	}
@@ -1061,9 +1107,8 @@ public class ConversationActivity extends BriarActivity
 		i.putExtra(ATTACHMENT_POSITION, attachments.indexOf(item));
 		i.putExtra(NAME, name);
 		i.putExtra(DATE, messageItem.getTime());
-		i.putExtra(ITEM_ID, messageItem.getId().getBytes());
 		// restoring list position should not trigger android bug #224270
-		String transitionName = item.getTransitionName(messageItem.getId());
+		String transitionName = item.getTransitionName();
 		ActivityOptionsCompat options =
 				makeSceneTransitionAnimation(this, view, transitionName);
 		ActivityCompat.startActivity(this, i, options.toBundle());
@@ -1102,37 +1147,15 @@ public class ConversationActivity extends BriarActivity
 		return text;
 	}
 
-	/**
-	 * Called by {@link PrivateMessageHeader#accept(ConversationMessageVisitor)}
-	 */
 	@Override
 	public List<AttachmentItem> getAttachmentItems(PrivateMessageHeader h) {
-		List<LiveData<AttachmentItem>> liveDataList =
-				attachmentRetriever.getAttachmentItems(h);
-		List<AttachmentItem> items = new ArrayList<>(liveDataList.size());
-		for (LiveData<AttachmentItem> liveData : liveDataList) {
-			liveData.observe(this, new AttachmentObserver(h.getId(), liveData));
-			items.add(requireNonNull(liveData.getValue()));
-		}
-		return items;
-	}
-
-	private class AttachmentObserver implements Observer<AttachmentItem> {
-		private final MessageId conversationMessageId;
-		private final LiveData<AttachmentItem> liveData;
-
-		private AttachmentObserver(MessageId conversationMessageId,
-				LiveData<AttachmentItem> liveData) {
-			this.conversationMessageId = conversationMessageId;
-			this.liveData = liveData;
-		}
-
-		@Override
-		public void onChanged(AttachmentItem attachmentItem) {
-			updateMessageAttachment(conversationMessageId, attachmentItem);
-			if (attachmentItem.getState().isFinal())
-				liveData.removeObserver(this);
+		List<AttachmentItem> attachments =
+				attachmentRetriever.cacheGet(h.getId());
+		if (attachments == null) {
+			loadMessageAttachments(h);
+			return emptyList();
 		}
+		return attachments;
 	}
 
 }

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

@@ -9,13 +9,12 @@ import java.util.List;
 import javax.annotation.concurrent.NotThreadSafe;
 
 import androidx.annotation.LayoutRes;
-import androidx.annotation.UiThread;
 
 @NotThreadSafe
 @NotNullByDefault
 class ConversationMessageItem extends ConversationItem {
 
-	private final List<AttachmentItem> attachments;
+	private List<AttachmentItem> attachments;
 
 	ConversationMessageItem(@LayoutRes int layoutRes, PrivateMessageHeader h,
 			List<AttachmentItem> attachments) {
@@ -27,14 +26,8 @@ class ConversationMessageItem extends ConversationItem {
 		return attachments;
 	}
 
-	@UiThread
-	boolean updateAttachments(AttachmentItem item) {
-		int pos = attachments.indexOf(item);
-		if (pos != -1 && attachments.get(pos).getState() != item.getState()) {
-			attachments.set(pos, item);
-			return true;
-		}
-		return false;
+	void setAttachments(List<AttachmentItem> attachments) {
+		this.attachments = attachments;
 	}
 
 }

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

@@ -2,7 +2,6 @@ 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;
@@ -17,7 +16,6 @@ import com.google.android.material.appbar.AppBarLayout;
 
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
-import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.activity.ActivityComponent;
 import org.briarproject.briar.android.activity.BriarActivity;
@@ -36,8 +34,6 @@ 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;
@@ -60,6 +56,7 @@ 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
@@ -70,7 +67,6 @@ public class ImageActivity extends BriarActivity
 	final static String ATTACHMENT_POSITION = "position";
 	final static String NAME = "name";
 	final static String DATE = "date";
-	final static String ITEM_ID = "itemId";
 
 	@RequiresApi(api = 16)
 	private final static int UI_FLAGS_DEFAULT =
@@ -84,7 +80,6 @@ public class ImageActivity extends BriarActivity
 	private AppBarLayout appBarLayout;
 	private ViewPager viewPager;
 	private List<AttachmentItem> attachments;
-	private MessageId conversationMessageId;
 
 	@Override
 	public void injectActivity(ActivityComponent component) {
@@ -139,7 +134,6 @@ public class ImageActivity extends BriarActivity
 		String date = formatDateAbsolute(this, time);
 		contactName.setText(name);
 		dateView.setText(date);
-		conversationMessageId = new MessageId(i.getByteArrayExtra(ITEM_ID));
 
 		// Set up image ViewPager
 		viewPager = findViewById(R.id.viewPager);
@@ -282,10 +276,7 @@ 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));
-		Drawable icon = ContextCompat.getDrawable(this, R.drawable.ic_security);
-		DrawableCompat.setTint(requireNonNull(icon),
-				ContextCompat.getColor(this, R.color.color_primary));
-		builder.setIcon(icon);
+		builder.setIcon(getDialogIcon(this, R.drawable.ic_security));
 		builder.setPositiveButton(R.string.save_image, okListener);
 		builder.setNegativeButton(R.string.cancel, null);
 		builder.show();
@@ -329,8 +320,8 @@ public class ImageActivity extends BriarActivity
 
 		@Override
 		public Fragment getItem(int position) {
-			Fragment f = ImageFragment.newInstance(
-					attachments.get(position), conversationMessageId, isFirst);
+			Fragment f = ImageFragment
+					.newInstance(attachments.get(position), isFirst);
 			isFirst = false;
 			return f;
 		}

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

@@ -49,8 +49,7 @@ class ImageAdapter extends Adapter<ImageViewHolder> {
 	public ImageViewHolder onCreateViewHolder(ViewGroup viewGroup, int type) {
 		View v = LayoutInflater.from(viewGroup.getContext()).inflate(
 				R.layout.list_item_image, viewGroup, false);
-		requireNonNull(conversationItem);
-		return new ImageViewHolder(v, imageSize, conversationItem.getId());
+		return new ImageViewHolder(v, imageSize);
 	}
 
 	@Override
@@ -59,7 +58,7 @@ class ImageAdapter extends Adapter<ImageViewHolder> {
 		// get item
 		requireNonNull(conversationItem);
 		AttachmentItem item = items.get(position);
-		// set onClick listener, if not missing or error
+		// set onClick listener
 		imageViewHolder.itemView.setOnClickListener(v ->
 				listener.onAttachmentClicked(v, conversationItem, item)
 		);

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

@@ -15,7 +15,6 @@ import com.bumptech.glide.request.target.Target;
 import com.github.chrisbanes.photoview.PhotoView;
 
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
-import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.activity.BaseActivity;
 import org.briarproject.briar.android.attachment.AttachmentItem;
@@ -24,7 +23,6 @@ import org.briarproject.briar.android.conversation.glide.GlideApp;
 import javax.annotation.ParametersAreNonnullByDefault;
 import javax.inject.Inject;
 
-import androidx.annotation.DrawableRes;
 import androidx.annotation.Nullable;
 import androidx.fragment.app.Fragment;
 import androidx.lifecycle.ViewModelProvider;
@@ -34,36 +32,27 @@ import static android.os.Build.VERSION.SDK_INT;
 import static android.widget.ImageView.ScaleType.FIT_START;
 import static com.bumptech.glide.load.engine.DiskCacheStrategy.NONE;
 import static org.briarproject.bramble.api.nullsafety.NullSafety.requireNonNull;
-import static org.briarproject.briar.android.attachment.AttachmentItem.State.AVAILABLE;
-import static org.briarproject.briar.android.attachment.AttachmentItem.State.ERROR;
 import static org.briarproject.briar.android.conversation.ImageActivity.ATTACHMENT_POSITION;
-import static org.briarproject.briar.android.conversation.ImageActivity.ITEM_ID;
 
 @MethodsNotNullByDefault
 @ParametersAreNonnullByDefault
-public class ImageFragment extends Fragment
-		implements RequestListener<Drawable> {
+public class ImageFragment extends Fragment {
 
 	private final static String IS_FIRST = "isFirst";
-	@DrawableRes
-	private static final int ERROR_RES = R.drawable.ic_image_broken;
 
 	@Inject
 	ViewModelProvider.Factory viewModelFactory;
 
 	private AttachmentItem attachment;
 	private boolean isFirst;
-	private MessageId conversationItemId;
 	private ImageViewModel viewModel;
 	private PhotoView photoView;
 
-	static ImageFragment newInstance(AttachmentItem a,
-			MessageId conversationMessageId, boolean isFirst) {
+	static ImageFragment newInstance(AttachmentItem a, boolean isFirst) {
 		ImageFragment f = new ImageFragment();
 		Bundle args = new Bundle();
 		args.putParcelable(ATTACHMENT_POSITION, a);
 		args.putBoolean(IS_FIRST, isFirst);
-		args.putByteArray(ITEM_ID, conversationMessageId.getBytes());
 		f.setArguments(args);
 		return f;
 	}
@@ -81,8 +70,6 @@ public class ImageFragment extends Fragment
 		Bundle args = requireNonNull(getArguments());
 		attachment = requireNonNull(args.getParcelable(ATTACHMENT_POSITION));
 		isFirst = args.getBoolean(IS_FIRST);
-		conversationItemId =
-				new MessageId(requireNonNull(args.getByteArray(ITEM_ID)));
 	}
 
 	@Nullable
@@ -95,72 +82,55 @@ public class ImageFragment extends Fragment
 
 		viewModel = ViewModelProviders.of(requireNonNull(getActivity()),
 				viewModelFactory).get(ImageViewModel.class);
-		viewModel.getOnAttachmentLoaded()
-				.observeEvent(this, this::onAttachmentLoaded);
 
 		photoView = v.findViewById(R.id.photoView);
 		photoView.setScaleLevels(1, 2, 4);
 		photoView.setOnClickListener(view -> viewModel.clickImage());
 
-		if (attachment.getState() == AVAILABLE) {
-			loadImage();
-			// postponed transition will be started when Image was loaded
-		} else if (attachment.getState() == ERROR) {
-			photoView.setImageResource(ERROR_RES);
-			startPostponedTransition();
-		} else {
-			photoView.setImageResource(R.drawable.ic_image_missing);
-			startPostponedTransition();
-		}
+		// Request Listener
+		RequestListener<Drawable> listener = new RequestListener<Drawable>() {
+
+			@Override
+			public boolean onLoadFailed(@Nullable GlideException e,
+					Object model, Target<Drawable> target,
+					boolean isFirstResource) {
+				if (getActivity() != null && isFirst)
+					getActivity().supportStartPostponedEnterTransition();
+				return false;
+			}
+
+			@Override
+			public boolean onResourceReady(Drawable resource, Object model,
+					Target<Drawable> target, DataSource dataSource,
+					boolean isFirstResource) {
+				if (SDK_INT >= 21 && !(resource instanceof Animatable)) {
+					// set transition name only when not animatable,
+					// because the animation won't start otherwise
+					photoView.setTransitionName(
+							attachment.getTransitionName());
+				}
+				// Move image to the top if overlapping toolbar
+				if (viewModel.isOverlappingToolbar(photoView, resource)) {
+					photoView.setScaleType(FIT_START);
+				}
+				if (getActivity() != null && isFirst) {
+					getActivity().supportStartPostponedEnterTransition();
+				}
+				return false;
+			}
+		};
+
+		// Load Image
+		GlideApp.with(this)
+				.load(attachment)
+				// TODO allow if size < maxTextureSize ?
+//				.override(SIZE_ORIGINAL)
+				.diskCacheStrategy(NONE)
+				.error(R.drawable.ic_image_broken)
+				.addListener(listener)
+				.into(photoView);
 
 		return v;
 	}
 
-	private void loadImage() {
-		GlideApp.with(this)
-				.load(attachment)
-				// TODO allow if size < maxTextureSize ?
-//					.override(SIZE_ORIGINAL)
-				.diskCacheStrategy(NONE)
-				.error(ERROR_RES)
-				.addListener(this)
-				.into(photoView);
-	}
-
-	private void onAttachmentLoaded(MessageId messageId) {
-		if (attachment.getMessageId().equals(messageId)) loadImage();
-	}
-
-	@Override
-	public boolean onLoadFailed(@Nullable GlideException e,
-			Object model, Target<Drawable> target,
-			boolean isFirstResource) {
-		startPostponedTransition();
-		return false;
-	}
-
-	@Override
-	public boolean onResourceReady(Drawable resource, Object model,
-			Target<Drawable> target, DataSource dataSource,
-			boolean isFirstResource) {
-		if (SDK_INT >= 21 && !(resource instanceof Animatable)) {
-			// set transition name only when not animatable,
-			// because the animation won't start otherwise
-			photoView.setTransitionName(
-					attachment.getTransitionName(conversationItemId));
-		}
-		// Move image to the top if overlapping toolbar
-		if (viewModel.isOverlappingToolbar(photoView, resource)) {
-			photoView.setScaleType(FIT_START);
-		}
-		startPostponedTransition();
-		return false;
-	}
-
-	private void startPostponedTransition() {
-		if (getActivity() != null && isFirst) {
-			getActivity().supportStartPostponedEnterTransition();
-		}
-	}
-
 }

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

@@ -7,7 +7,6 @@ import android.widget.ImageView;
 import com.bumptech.glide.load.Transformation;
 
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.attachment.AttachmentItem;
 import org.briarproject.briar.android.conversation.glide.BriarImageTransformation;
@@ -19,12 +18,8 @@ import androidx.recyclerview.widget.RecyclerView.ViewHolder;
 import androidx.recyclerview.widget.StaggeredGridLayoutManager.LayoutParams;
 
 import static android.os.Build.VERSION.SDK_INT;
-import static android.widget.ImageView.ScaleType.CENTER_CROP;
-import static android.widget.ImageView.ScaleType.FIT_CENTER;
 import static com.bumptech.glide.load.engine.DiskCacheStrategy.NONE;
 import static com.bumptech.glide.load.resource.drawable.DrawableTransitionOptions.withCrossFade;
-import static org.briarproject.briar.android.attachment.AttachmentItem.State.AVAILABLE;
-import static org.briarproject.briar.android.attachment.AttachmentItem.State.ERROR;
 
 @NotNullByDefault
 class ImageViewHolder extends ViewHolder {
@@ -34,33 +29,25 @@ class ImageViewHolder extends ViewHolder {
 
 	protected final ImageView imageView;
 	private final int imageSize;
-	private final MessageId conversationItemId;
 
-	ImageViewHolder(View v, int imageSize, MessageId conversationItemId) {
+	ImageViewHolder(View v, int imageSize) {
 		super(v);
 		imageView = v.findViewById(R.id.imageView);
 		this.imageSize = imageSize;
-		this.conversationItemId = conversationItemId;
 	}
 
 	void bind(AttachmentItem attachment, Radii r, boolean single,
 			boolean needsStretch) {
-		setImageViewDimensions(attachment, single, needsStretch);
-		if (attachment.getState() != AVAILABLE) {
-			GlideApp.with(imageView).clear(imageView);
-			if (attachment.getState() == ERROR) {
-				imageView.setImageResource(ERROR_RES);
-			} else {
-				imageView.setImageResource(R.drawable.ic_image_missing);
-			}
-			imageView.setScaleType(FIT_CENTER);
+		if (attachment.hasError()) {
+			GlideApp.with(imageView)
+					.clear(imageView);
+			imageView.setImageResource(ERROR_RES);
 		} else {
+			setImageViewDimensions(attachment, single, needsStretch);
 			loadImage(attachment, r);
-			imageView.setScaleType(CENTER_CROP);
-		}
-		if (SDK_INT >= 21) {
-			imageView.setTransitionName(
-					attachment.getTransitionName(conversationItemId));
+			if (SDK_INT >= 21) {
+				imageView.setTransitionName(attachment.getTransitionName());
+			}
 		}
 	}
 

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

@@ -7,18 +7,13 @@ import android.view.View;
 
 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.IoExecutor;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.briar.android.attachment.AttachmentItem;
 import org.briarproject.briar.android.viewmodel.LiveEvent;
 import org.briarproject.briar.android.viewmodel.MutableLiveEvent;
 import org.briarproject.briar.api.messaging.Attachment;
 import org.briarproject.briar.api.messaging.MessagingManager;
-import org.briarproject.briar.api.messaging.event.AttachmentReceivedEvent;
 
 import java.io.File;
 import java.io.FileOutputStream;
@@ -46,19 +41,16 @@ import static org.briarproject.bramble.util.IoUtils.copyAndClose;
 import static org.briarproject.bramble.util.LogUtils.logException;
 
 @NotNullByDefault
-public class ImageViewModel extends AndroidViewModel implements EventListener {
+public class ImageViewModel extends AndroidViewModel {
 
 	private static Logger LOG = getLogger(ImageViewModel.class.getName());
 
 	private final MessagingManager messagingManager;
-	private final EventBus eventBus;
 	@DatabaseExecutor
 	private final Executor dbExecutor;
 	@IoExecutor
 	private final Executor ioExecutor;
 
-	private final MutableLiveEvent<MessageId> attachmentLoaded =
-			new MutableLiveEvent<>();
 	/**
 	 * true means there was an error saving the image, false if image was saved.
 	 */
@@ -70,34 +62,13 @@ public class ImageViewModel extends AndroidViewModel implements EventListener {
 
 	@Inject
 	ImageViewModel(Application application,
-			MessagingManager messagingManager, EventBus eventBus,
+			MessagingManager messagingManager,
 			@DatabaseExecutor Executor dbExecutor,
 			@IoExecutor Executor ioExecutor) {
 		super(application);
 		this.messagingManager = messagingManager;
-		this.eventBus = eventBus;
 		this.dbExecutor = dbExecutor;
 		this.ioExecutor = ioExecutor;
-
-		eventBus.addListener(this);
-	}
-
-	@Override
-	protected void onCleared() {
-		super.onCleared();
-		eventBus.removeListener(this);
-	}
-
-	@Override
-	public void eventOccurred(Event e) {
-		if (e instanceof AttachmentReceivedEvent) {
-			attachmentLoaded
-					.postEvent(((AttachmentReceivedEvent) e).getMessageId());
-		}
-	}
-
-	LiveEvent<MessageId> getOnAttachmentLoaded() {
-		return attachmentLoaded;
 	}
 
 	void clickImage() {

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

@@ -9,6 +9,7 @@ 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;
@@ -79,13 +80,13 @@ public class ContactExchangeActivity extends KeyAgreementActivity {
 
 	@UiThread
 	private void contactExchangeFailed() {
-		showErrorFragment(R.string.connection_error_explanation);
+		showErrorFragment();
 	}
 
 	@UiThread
 	@Override
 	public void keyAgreementFailed() {
-		showErrorFragment(R.string.connection_error_explanation);
+		showErrorFragment();
 	}
 
 	@UiThread
@@ -103,7 +104,7 @@ public class ContactExchangeActivity extends KeyAgreementActivity {
 	@UiThread
 	@Override
 	public void keyAgreementAborted(boolean remoteAborted) {
-		showErrorFragment(R.string.connection_error_explanation);
+		showErrorFragment();
 	}
 
 	@UiThread
@@ -112,4 +113,10 @@ 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

@@ -8,10 +8,18 @@ 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;
@@ -37,13 +45,15 @@ 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;
 
@@ -51,10 +61,33 @@ import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_PERMI
 @ParametersNotNullByDefault
 public abstract class KeyAgreementActivity extends BriarActivity implements
 		BaseFragmentListener, IntroScreenSeenListener,
-		KeyAgreementEventListener {
+		KeyAgreementEventListener, EventListener {
 
-	private enum BluetoothState {
-		UNKNOWN, NO_ADAPTER, WAITING, REFUSED, ENABLED, DISCOVERABLE
+	private enum BluetoothDecision {
+		/**
+		 * 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 {
@@ -62,11 +95,14 @@ public abstract class KeyAgreementActivity extends BriarActivity implements
 	}
 
 	private static final Logger LOG =
-			Logger.getLogger(KeyAgreementActivity.class.getName());
+			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
@@ -74,21 +110,36 @@ 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 BluetoothState bluetoothState = BluetoothState.UNKNOWN;
+	private BluetoothDecision bluetoothDecision = BluetoothDecision.UNKNOWN;
 	private BroadcastReceiver bluetoothReceiver = null;
 
 	@Override
@@ -96,20 +147,17 @@ 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);
-		getSupportActionBar().setDisplayHomeAsUpEnabled(true);
+		requireNonNull(getSupportActionBar()).setDisplayHomeAsUpEnabled(true);
 		if (state == null) {
 			showInitialFragment(IntroFragment.newInstance());
 		}
-		IntentFilter filter = new IntentFilter();
-		filter.addAction(ACTION_STATE_CHANGED);
-		filter.addAction(ACTION_SCAN_MODE_CHANGED);
+		IntentFilter filter = new IntentFilter(ACTION_SCAN_MODE_CHANGED);
 		bluetoothReceiver = new BluetoothStateReceiver();
 		registerReceiver(bluetoothReceiver, filter);
 	}
@@ -122,18 +170,17 @@ public abstract class KeyAgreementActivity extends BriarActivity implements
 
 	@Override
 	public boolean onOptionsItemSelected(MenuItem item) {
-		switch (item.getItemId()) {
-			case android.R.id.home:
-				onBackPressed();
-				return true;
-			default:
-				return super.onOptionsItemSelected(item);
+		if (item.getItemId() == android.R.id.home) {
+			onBackPressed();
+			return true;
 		}
+		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;
@@ -150,11 +197,22 @@ public abstract class KeyAgreementActivity extends BriarActivity implements
 
 	private void showQrCodeFragmentIfAllowed() {
 		if (isResumed && continueClicked && areEssentialPermissionsGranted()) {
-			if (bluetoothState == BluetoothState.UNKNOWN ||
-					bluetoothState == BluetoothState.ENABLED) {
-				requestBluetoothDiscoverable();
-			} else if (bluetoothState != BluetoothState.WAITING) {
+			if (isWifiReady() && isBluetoothReady()) {
+				LOG.info("Wifi and Bluetooth are ready");
 				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);
+				}
 			}
 		}
 	}
@@ -167,57 +225,108 @@ 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, Intent data) {
+	public void onActivityResult(int request, int result,
+			@Nullable Intent data) {
 		if (request == REQUEST_BLUETOOTH_DISCOVERABLE) {
 			if (result == RESULT_CANCELED) {
-				setBluetoothState(BluetoothState.REFUSED);
+				LOG.info("Bluetooth discoverability was refused");
+				bluetoothDecision = BluetoothDecision.REFUSED;
 			} else {
-				// If Bluetooth is already discoverable, show the QR code -
-				// otherwise wait for the state or scan mode to change
-				BluetoothAdapter bt = BluetoothAdapter.getDefaultAdapter();
-				if (bt == null) throw new AssertionError();
-				if (bt.getScanMode() == SCAN_MODE_CONNECTABLE_DISCOVERABLE)
-					setBluetoothState(BluetoothState.DISCOVERABLE);
+				LOG.info("Bluetooth discoverability was accepted");
+				bluetoothDecision = BluetoothDecision.ACCEPTED;
+				if (!wasAdapterEnabled) {
+					LOG.info("Bluetooth adapter was enabled by us");
+					eventBus.broadcast(new BluetoothEnabledEvent());
+					wasAdapterEnabled = true;
+				}
 			}
+			showQrCodeFragmentIfAllowed();
 		} else super.onActivityResult(request, result, data);
 	}
 
@@ -227,7 +336,12 @@ 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
-		bluetoothState = BluetoothState.UNKNOWN;
+		bluetoothDecision = BluetoothDecision.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) {
@@ -239,12 +353,6 @@ 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
@@ -335,24 +443,30 @@ 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) {
-			String action = intent.getAction();
-			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);
-			}
+			LOG.info("Bluetooth scan mode changed");
+			showQrCodeFragmentIfAllowed();
 		}
 	}
 }

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

@@ -1,16 +1,12 @@
 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;
 
@@ -21,16 +17,11 @@ 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;
@@ -38,23 +29,21 @@ 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;
@@ -72,8 +61,7 @@ import static org.briarproject.briar.android.util.UiUtils.getDaysUntilExpiry;
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
 public class NavDrawerActivity extends BriarActivity implements
-		BaseFragmentListener, TransportStateListener,
-		OnNavigationItemSelectedListener {
+		BaseFragmentListener, OnNavigationItemSelectedListener {
 
 	private static final Logger LOG =
 			getLogger(NavDrawerActivity.class.getName());
@@ -91,19 +79,18 @@ 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
-	NavDrawerController controller;
+	ViewModelProvider.Factory viewModelFactory;
+
 	@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);
@@ -115,10 +102,20 @@ 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());
@@ -131,9 +128,6 @@ 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)) {
@@ -149,17 +143,10 @@ public class NavDrawerActivity extends BriarActivity implements
 	}
 
 	@Override
-	@SuppressLint("NewApi")
 	public void onStart() {
 		super.onStart();
-		updateTransports();
 		lockManager.checkIfLockable();
-		controller.showExpiryWarning(new UiResultHandler<Boolean>(this) {
-			@Override
-			public void onResultUi(Boolean expiry) {
-				if (expiry) showExpiryWarning();
-			}
-		});
+		viewModel.checkExpiryWarning();
 	}
 
 	@Override
@@ -167,16 +154,7 @@ public class NavDrawerActivity extends BriarActivity implements
 			@Nullable Intent data) {
 		super.onActivityResult(request, result, data);
 		if (request == REQUEST_PASSWORD && result == RESULT_OK) {
-			controller.shouldAskForDozeWhitelisting(this,
-					new UiResultHandler<Boolean>(this) {
-						@Override
-						public void onResultUi(Boolean ask) {
-							if (ask) {
-								showDozeDialog(
-										getString(R.string.setup_doze_intro));
-							}
-						}
-					});
+			viewModel.checkDozeWhitelisting();
 		}
 	}
 
@@ -346,134 +324,30 @@ public class NavDrawerActivity extends BriarActivity implements
 		if (item != null) item.setVisible(visible);
 	}
 
-	private void showExpiryWarning() {
+	private void showExpiryWarning(boolean show) {
 		int daysUntilExpiry = getDaysUntilExpiry();
-		if (daysUntilExpiry < 0) signOut();
+		if (daysUntilExpiry < 0) {
+			signOut();
+			return;
+		}
 
-		// show expiry warning text
 		ViewGroup expiryWarning = findViewById(R.id.expiryWarning);
-		TextView expiryWarningText =
-				expiryWarning.findViewById(R.id.expiryWarningText);
-		// make close button functional
-		ImageView expiryWarningClose =
-				expiryWarning.findViewById(R.id.expiryWarningClose);
-
-		expiryWarningText.setText(getResources()
-				.getQuantityString(R.plurals.expiry_warning,
-						daysUntilExpiry, daysUntilExpiry));
-
-		expiryWarningClose.setOnClickListener(v -> {
-			controller.expiryWarningDismissed();
+		if (show) {
+			// show expiry warning text
+			TextView expiryWarningText =
+					expiryWarning.findViewById(R.id.expiryWarningText);
+			String text = getResources().getQuantityString(
+					R.plurals.expiry_warning, daysUntilExpiry, daysUntilExpiry);
+			expiryWarningText.setText(text);
+			// make close button functional
+			ImageView expiryWarningClose =
+					expiryWarning.findViewById(R.id.expiryWarningClose);
+			expiryWarningClose.setOnClickListener(v ->
+					viewModel.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

@@ -1,22 +0,0 @@
-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

@@ -1,182 +0,0 @@
-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

@@ -0,0 +1,19 @@
+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);
+
+}

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

@@ -0,0 +1,255 @@
+package org.briarproject.briar.android.navdrawer;
+
+import android.app.Application;
+
+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.nullsafety.NotNullByDefault;
+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.TorConstants;
+import org.briarproject.bramble.api.plugin.TransportId;
+import org.briarproject.bramble.api.plugin.event.TransportStateEvent;
+import org.briarproject.bramble.api.settings.Settings;
+import org.briarproject.bramble.api.settings.SettingsManager;
+import org.briarproject.bramble.api.system.LocationUtils;
+
+import java.util.concurrent.Executor;
+import java.util.logging.Logger;
+
+import javax.inject.Inject;
+
+import androidx.annotation.Nullable;
+import androidx.annotation.UiThread;
+import androidx.lifecycle.AndroidViewModel;
+import androidx.lifecycle.LiveData;
+import androidx.lifecycle.MutableLiveData;
+
+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.api.plugin.Plugin.PREF_PLUGIN_ENABLE;
+import static org.briarproject.bramble.api.plugin.Plugin.State.STARTING_STOPPING;
+import static org.briarproject.bramble.api.plugin.TorConstants.PREF_TOR_MOBILE;
+import static org.briarproject.bramble.api.plugin.TorConstants.PREF_TOR_NETWORK;
+import static org.briarproject.bramble.api.plugin.TorConstants.PREF_TOR_NETWORK_WITH_BRIDGES;
+import static org.briarproject.bramble.api.plugin.TorConstants.PREF_TOR_ONLY_WHEN_CHARGING;
+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.getCountryDisplayName;
+import static org.briarproject.briar.android.util.UiUtils.needsDozeWhitelisting;
+
+@NotNullByDefault
+public class NavDrawerViewModel extends AndroidViewModel
+		implements EventListener {
+
+	private static final Logger LOG =
+			getLogger(NavDrawerViewModel.class.getName());
+
+	private static final String EXPIRY_DATE_WARNING = "expiryDateWarning";
+	static final TransportId[] TRANSPORT_IDS =
+			{TorConstants.ID, LanTcpConstants.ID, BluetoothConstants.ID};
+
+	@DatabaseExecutor
+	private final Executor dbExecutor;
+	private final SettingsManager settingsManager;
+	private final PluginManager pluginManager;
+	private final LocationUtils locationUtils;
+	private final EventBus eventBus;
+
+	private final MutableLiveData<Boolean> showExpiryWarning =
+			new MutableLiveData<>();
+	private final MutableLiveData<Boolean> shouldAskForDozeWhitelisting =
+			new MutableLiveData<>();
+
+	private final MutableLiveData<Plugin.State> torPluginState =
+			new MutableLiveData<>();
+	private final MutableLiveData<Plugin.State> wifiPluginState =
+			new MutableLiveData<>();
+	private final MutableLiveData<Plugin.State> btPluginState =
+			new MutableLiveData<>();
+
+	@Inject
+	NavDrawerViewModel(Application app, @DatabaseExecutor Executor dbExecutor,
+			SettingsManager settingsManager, PluginManager pluginManager,
+			LocationUtils locationUtils, EventBus eventBus) {
+		super(app);
+		this.dbExecutor = dbExecutor;
+		this.settingsManager = settingsManager;
+		this.pluginManager = pluginManager;
+		this.locationUtils = locationUtils;
+		this.eventBus = eventBus;
+		eventBus.addListener(this);
+		updatePluginStates();
+	}
+
+	@Override
+	protected void onCleared() {
+		eventBus.removeListener(this);
+	}
+
+	@Override
+	public void eventOccurred(Event e) {
+		if (e instanceof TransportStateEvent) {
+			TransportStateEvent t = (TransportStateEvent) e;
+			TransportId id = t.getTransportId();
+			State state = t.getState();
+			if (LOG.isLoggable(INFO)) {
+				LOG.info("TransportStateEvent: " + id + " is " + state);
+			}
+			MutableLiveData<Plugin.State> liveData = getPluginLiveData(id);
+			if (liveData != null) liveData.postValue(state);
+		}
+	}
+
+	LiveData<Boolean> showExpiryWarning() {
+		return showExpiryWarning;
+	}
+
+	@UiThread
+	void checkExpiryWarning() {
+		if (!IS_DEBUG_BUILD) {
+			showExpiryWarning.setValue(false);
+			return;
+		}
+		dbExecutor.execute(() -> {
+			try {
+				Settings settings =
+						settingsManager.getSettings(SETTINGS_NAMESPACE);
+				int warningInt = settings.getInt(EXPIRY_DATE_WARNING, 0);
+
+				if (warningInt == 0) {
+					// we have not warned before
+					showExpiryWarning.postValue(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) {
+						showExpiryWarning.postValue(true);
+					} else if (daysBeforeExpiry <= 3 &&
+							daysSinceLastWarning > 0) {
+						showExpiryWarning.postValue(true);
+					} else {
+						showExpiryWarning.postValue(false);
+					}
+				}
+			} catch (DbException e) {
+				logException(LOG, WARNING, e);
+			}
+		});
+	}
+
+	@UiThread
+	void expiryWarningDismissed() {
+		showExpiryWarning.setValue(false);
+		dbExecutor.execute(() -> {
+			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);
+			}
+		});
+	}
+
+	LiveData<Boolean> shouldAskForDozeWhitelisting() {
+		return shouldAskForDozeWhitelisting;
+	}
+
+	@UiThread
+	void checkDozeWhitelisting() {
+		// check this first, to hit the DbThread only when really necessary
+		if (!needsDozeWhitelisting(getApplication())) {
+			shouldAskForDozeWhitelisting.setValue(false);
+			return;
+		}
+		dbExecutor.execute(() -> {
+			try {
+				Settings settings =
+						settingsManager.getSettings(SETTINGS_NAMESPACE);
+				boolean ask = settings.getBoolean(DOZE_ASK_AGAIN, true);
+				shouldAskForDozeWhitelisting.postValue(ask);
+			} catch (DbException e) {
+				logException(LOG, WARNING, e);
+				shouldAskForDozeWhitelisting.postValue(true);
+			}
+		});
+	}
+
+	private void updatePluginStates() {
+		for (TransportId t : TRANSPORT_IDS) {
+			MutableLiveData<Plugin.State> liveData = getPluginLiveData(t);
+			if (liveData == null) throw new AssertionError();
+			liveData.setValue(getTransportState(t));
+		}
+	}
+
+	private State getTransportState(TransportId id) {
+		Plugin plugin = pluginManager.getPlugin(id);
+		return plugin == null ? STARTING_STOPPING : plugin.getState();
+	}
+
+	@Nullable
+	private MutableLiveData<State> getPluginLiveData(TransportId t) {
+		if (t.equals(TorConstants.ID)) {
+			return torPluginState;
+		} else if (t.equals(LanTcpConstants.ID)) {
+			return wifiPluginState;
+		} else if (t.equals(BluetoothConstants.ID)) {
+			return btPluginState;
+		} else {
+			return null;
+		}
+	}
+
+	LiveData<State> getPluginState(TransportId t) {
+		LiveData<Plugin.State> liveData = getPluginLiveData(t);
+		if (liveData == null) throw new AssertionError();
+		return liveData;
+	}
+
+	int getReasonsDisabled(TransportId id) {
+		Plugin plugin = pluginManager.getPlugin(id);
+		return plugin == null ? 0 : plugin.getReasonsDisabled();
+	}
+
+	void setPluginEnabled(TransportId t, boolean enabled) {
+		pluginManager.setPluginEnabled(t, enabled);
+	}
+
+	void setTorEnabled(boolean battery, boolean mobileData, boolean location) {
+		Settings s = new Settings();
+		s.putBoolean(PREF_PLUGIN_ENABLE, true);
+		if (battery) s.putBoolean(PREF_TOR_ONLY_WHEN_CHARGING, false);
+		if (mobileData) s.putBoolean(PREF_TOR_MOBILE, true);
+		if (location) s.putInt(PREF_TOR_NETWORK, PREF_TOR_NETWORK_WITH_BRIDGES);
+		dbExecutor.execute(() -> {
+			try {
+				settingsManager.mergeSettings(s, TorConstants.ID.getString());
+			} catch (DbException e) {
+				logException(LOG, WARNING, e);
+			}
+		});
+	}
+
+	String getCurrentCountryName() {
+		return getCountryDisplayName(locationUtils.getCurrentCountry());
+	}
+}

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

@@ -0,0 +1,213 @@
+package org.briarproject.briar.android.navdrawer;
+
+import android.content.Intent;
+import android.content.pm.PackageManager;
+import android.view.View;
+import android.widget.ImageView;
+import android.widget.ScrollView;
+
+import org.briarproject.bramble.api.plugin.BluetoothConstants;
+import org.briarproject.bramble.api.plugin.LanTcpConstants;
+import org.briarproject.bramble.api.plugin.Plugin.State;
+import org.briarproject.bramble.api.plugin.TorConstants;
+import org.briarproject.bramble.api.plugin.TransportId;
+import org.briarproject.briar.R;
+
+import androidx.appcompat.app.AlertDialog;
+import androidx.appcompat.app.AppCompatActivity;
+import androidx.appcompat.widget.AppCompatImageButton;
+import androidx.appcompat.widget.SwitchCompat;
+import androidx.constraintlayout.widget.ConstraintLayout;
+import androidx.constraintlayout.widget.ConstraintSet;
+import androidx.core.app.ActivityCompat;
+
+import static android.bluetooth.BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE;
+import static android.bluetooth.BluetoothAdapter.EXTRA_DISCOVERABLE_DURATION;
+import static android.os.Build.VERSION.SDK_INT;
+import static android.transition.TransitionManager.beginDelayedTransition;
+import static android.view.View.FOCUS_DOWN;
+import static androidx.core.content.ContextCompat.getColor;
+import static org.briarproject.bramble.api.plugin.Plugin.REASON_USER;
+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.STARTING_STOPPING;
+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.briar.android.navdrawer.NavDrawerViewModel.TRANSPORT_IDS;
+import static org.briarproject.briar.android.util.UiUtils.getDialogIcon;
+
+class PluginViewController {
+
+	private final AppCompatActivity activity;
+	private final NavDrawerViewModel viewModel;
+	private final ConstraintLayout drawerContent;
+	private final ConstraintSet collapsedConstraints, expandedConstraints;
+	private final AppCompatImageButton chevronView;
+	private final ImageView torIcon, wifiIcon, btIcon;
+	private final SwitchCompat torSwitch, wifiSwitch, btSwitch;
+
+	private boolean expanded = false;
+
+	PluginViewController(View v, AppCompatActivity activity,
+			NavDrawerViewModel viewModel) {
+		this.activity = activity;
+		this.viewModel = viewModel;
+		drawerContent = v.findViewById(R.id.drawerContent);
+
+		collapsedConstraints = new ConstraintSet();
+		collapsedConstraints.clone(v.getContext(),
+				R.layout.navigation_menu_collapsed);
+
+		expandedConstraints = new ConstraintSet();
+		expandedConstraints.clone(v.getContext(),
+				R.layout.navigation_menu_expanded);
+
+		// Scroll the drawer to the bottom when the view is expanded/collapsed
+		ScrollView scrollView = v.findViewById(R.id.drawerScrollView);
+		drawerContent.addOnLayoutChangeListener((view, left, top, right,
+				bottom, oldLeft, oldTop, oldRight, oldBottom) ->
+				scrollView.fullScroll(FOCUS_DOWN));
+
+		// Clicking the chevron expands or collapses the view
+		chevronView = v.findViewById(R.id.chevronView);
+		chevronView.setOnClickListener(view -> expandOrCollapseView());
+
+		// The whole view is clickable when collapsed
+		v.findViewById(R.id.connectionsBackground).setOnClickListener(view ->
+				expandOrCollapseView());
+
+		torIcon = v.findViewById(R.id.torIcon);
+		wifiIcon = v.findViewById(R.id.wifiIcon);
+		btIcon = v.findViewById(R.id.btIcon);
+
+		torSwitch = v.findViewById(R.id.torSwitch);
+		wifiSwitch = v.findViewById(R.id.wifiSwitch);
+		btSwitch = v.findViewById(R.id.btSwitch);
+
+		for (TransportId t : TRANSPORT_IDS) {
+			// a OnCheckedChangeListener would get triggered on programmatic updates
+			SwitchCompat switchCompat = getSwitch(t);
+			switchCompat.setOnClickListener(buttonView -> {
+				if (switchCompat.isChecked()) tryToEnablePlugin(t);
+				else viewModel.setPluginEnabled(t, false);
+				// Revert the switch to its previous state until the plugin
+				// changes its state
+				switchCompat.toggle();
+			});
+			viewModel.getPluginState(t).observe(activity, state ->
+					stateUpdate(t, state));
+		}
+	}
+
+	private void expandOrCollapseView() {
+		if (SDK_INT >= 19) beginDelayedTransition(drawerContent);
+		if (expanded) {
+			collapsedConstraints.applyTo(drawerContent);
+			chevronView.setImageResource(R.drawable.chevron_up_white);
+		} else {
+			expandedConstraints.applyTo(drawerContent);
+			chevronView.setImageResource(R.drawable.chevron_down_white);
+		}
+		expanded = !expanded;
+	}
+
+	private void tryToEnablePlugin(TransportId id) {
+		if (id.equals(TorConstants.ID)) {
+			int reasons = viewModel.getReasonsDisabled(id);
+			if (reasons == 0 || reasons == REASON_USER) {
+				viewModel.setPluginEnabled(id, true);
+			} else {
+				showTorSettingsDialog(reasons);
+			}
+		} else if (id.equals(BluetoothConstants.ID)) {
+			Intent i = new Intent(ACTION_REQUEST_DISCOVERABLE);
+			i.putExtra(EXTRA_DISCOVERABLE_DURATION, 0);
+			PackageManager pm = activity.getPackageManager();
+			if (i.resolveActivity(pm) != null) {
+				ActivityCompat.startActivity(activity, i, null);
+			}
+			viewModel.setPluginEnabled(id, true);
+		} else {
+			viewModel.setPluginEnabled(id, true);
+		}
+	}
+
+	private void stateUpdate(TransportId id, State state) {
+		updateIcon(getIcon(id), state);
+		updateSwitch(getSwitch(id), state);
+	}
+
+	private SwitchCompat getSwitch(TransportId id) {
+		if (id == TorConstants.ID) return torSwitch;
+		if (id == BluetoothConstants.ID) return btSwitch;
+		if (id == LanTcpConstants.ID) return wifiSwitch;
+		throw new AssertionError();
+	}
+
+	private void updateSwitch(SwitchCompat switchCompat, State state) {
+		boolean checked = state != STARTING_STOPPING && state != DISABLED;
+		switchCompat.setChecked(checked);
+		switchCompat.setEnabled(state != STARTING_STOPPING);
+	}
+
+	private ImageView getIcon(TransportId id) {
+		if (id == TorConstants.ID) return torIcon;
+		if (id == BluetoothConstants.ID) return btIcon;
+		if (id == LanTcpConstants.ID) return wifiIcon;
+		throw new AssertionError();
+	}
+
+	private void updateIcon(ImageView icon, State state) {
+		int colorRes;
+		if (state == ACTIVE) {
+			colorRes = R.color.briar_green_light;
+		} else if (state == ENABLING) {
+			colorRes = R.color.briar_yellow;
+		} else {
+			colorRes = android.R.color.tertiary_text_light;
+		}
+		int color = getColor(icon.getContext(), colorRes);
+		icon.setColorFilter(color);
+	}
+
+	private void showTorSettingsDialog(int reasonsDisabled) {
+		boolean battery = (reasonsDisabled & REASON_BATTERY) != 0;
+		boolean mobileData = (reasonsDisabled & REASON_MOBILE_DATA) != 0;
+		boolean location = (reasonsDisabled & REASON_COUNTRY_BLOCKED) != 0;
+
+		StringBuilder s = new StringBuilder();
+		if (location) {
+			s.append("\t\u2022 ");
+			s.append(activity.getString(R.string.tor_override_network_setting,
+					viewModel.getCurrentCountryName()));
+			s.append('\n');
+		}
+		if (mobileData) {
+			s.append("\t\u2022 ");
+			s.append(activity.getString(
+					R.string.tor_override_mobile_data_setting));
+			s.append('\n');
+		}
+		if (battery) {
+			s.append("\t\u2022 ");
+			s.append(activity.getString(R.string.tor_only_when_charging_title));
+			s.append('\n');
+		}
+		String message = activity.getString(
+				R.string.tor_override_settings_body, s.toString());
+
+		AlertDialog.Builder b =
+				new AlertDialog.Builder(activity, R.style.BriarDialogTheme);
+		b.setTitle(R.string.tor_override_settings_title);
+		b.setIcon(getDialogIcon(activity, R.drawable.ic_settings_black_24dp));
+		b.setMessage(message);
+		b.setPositiveButton(R.string.tor_override_settings_confirm,
+				(dialog, which) ->
+						viewModel.setTorEnabled(battery, mobileData, location));
+		b.setNegativeButton(R.string.cancel, (dialog, which) ->
+				dialog.dismiss());
+		b.show();
+	}
+}

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

@@ -1,11 +0,0 @@
-package org.briarproject.briar.android.navdrawer;
-
-import org.briarproject.bramble.api.plugin.TransportId;
-
-import androidx.annotation.UiThread;
-
-interface TransportStateListener {
-
-	@UiThread
-	void stateUpdate(TransportId id, boolean enabled);
-}

briar-android/src/main/java/org/briarproject/briar/android/privategroup/list/GroupListController.java

@@ -10,8 +10,6 @@ import org.briarproject.briar.api.privategroup.GroupMessageHeader;
 
 import java.util.Collection;
 
-import javax.annotation.Nullable;
-
 import androidx.annotation.UiThread;
 
 @NotNullByDefault
@@ -21,7 +19,10 @@ interface GroupListController extends DbController {
 	 * The listener must be set right after the controller was injected
 	 */
 	@UiThread
-	void setGroupListListener(@Nullable GroupListListener listener);
+	void setGroupListListener(GroupListListener listener);
+
+	@UiThread
+	void unsetGroupListListener(GroupListListener listener);
 
 	@UiThread
 	void onStart();

briar-android/src/main/java/org/briarproject/briar/android/privategroup/list/GroupListControllerImpl.java

@@ -80,10 +80,15 @@ class GroupListControllerImpl extends DbControllerImpl
 	}
 
 	@Override
-	public void setGroupListListener(@Nullable GroupListListener listener) {
+	public void setGroupListListener(GroupListListener listener) {
 		this.listener = listener;
 	}
 
+	@Override
+	public void unsetGroupListListener(GroupListListener listener) {
+		if (this.listener == listener) this.listener = null;
+	}
+
 	@Override
 	@CallSuper
 	public void onStart() {

briar-android/src/main/java/org/briarproject/briar/android/privategroup/list/GroupListFragment.java

@@ -112,7 +112,7 @@ public class GroupListFragment extends BaseFragment implements
 	@Override
 	public void onDestroy() {
 		super.onDestroy();
-		controller.setGroupListListener(null);
+		controller.unsetGroupListListener(this);
 	}
 
 	@Override

briar-android/src/main/java/org/briarproject/briar/android/settings/SettingsFragment.java

@@ -20,7 +20,6 @@ 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.TorConstants;
 import org.briarproject.bramble.api.settings.Settings;
 import org.briarproject.bramble.api.settings.SettingsManager;
@@ -41,6 +40,7 @@ import java.util.logging.Logger;
 
 import javax.inject.Inject;
 
+import androidx.annotation.Nullable;
 import androidx.annotation.StringRes;
 import androidx.core.content.ContextCompat;
 import androidx.core.text.TextUtilsCompat;
@@ -72,10 +72,11 @@ import static android.widget.Toast.LENGTH_SHORT;
 import static androidx.core.view.ViewCompat.LAYOUT_DIRECTION_LTR;
 import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
-import static org.briarproject.bramble.api.plugin.BluetoothConstants.PREF_BT_ENABLE;
+import static org.briarproject.bramble.api.plugin.Plugin.PREF_PLUGIN_ENABLE;
 import static org.briarproject.bramble.api.plugin.TorConstants.PREF_TOR_MOBILE;
 import static org.briarproject.bramble.api.plugin.TorConstants.PREF_TOR_NETWORK;
 import static org.briarproject.bramble.api.plugin.TorConstants.PREF_TOR_NETWORK_AUTOMATIC;
+import static org.briarproject.bramble.api.plugin.TorConstants.PREF_TOR_NETWORK_NEVER;
 import static org.briarproject.bramble.api.plugin.TorConstants.PREF_TOR_ONLY_WHEN_CHARGING;
 import static org.briarproject.bramble.util.LogUtils.logDuration;
 import static org.briarproject.bramble.util.LogUtils.logException;
@@ -84,6 +85,7 @@ import static org.briarproject.briar.android.BriarApplication.ENTRY_ACTIVITY;
 import static org.briarproject.briar.android.TestingConstants.IS_DEBUG_BUILD;
 import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_RINGTONE;
 import static org.briarproject.briar.android.navdrawer.NavDrawerActivity.SIGN_OUT_URI;
+import static org.briarproject.briar.android.util.UiUtils.getCountryDisplayName;
 import static org.briarproject.briar.android.util.UiUtils.hasScreenLock;
 import static org.briarproject.briar.android.util.UiUtils.triggerFeedback;
 import static org.briarproject.briar.api.android.AndroidNotificationManager.BLOG_CHANNEL_ID;
@@ -105,16 +107,16 @@ public class SettingsFragment extends PreferenceFragmentCompat
 		implements EventListener, OnPreferenceChangeListener {
 
 	public static final String SETTINGS_NAMESPACE = "android-ui";
-	public static final String BT_NAMESPACE = BluetoothConstants.ID.getString();
-	public static final String TOR_NAMESPACE = TorConstants.ID.getString();
 	public static final String LANGUAGE = "pref_key_language";
 	public static final String PREF_SCREEN_LOCK = "pref_key_lock";
 	public static final String PREF_SCREEN_LOCK_TIMEOUT =
 			"pref_key_lock_timeout";
 	public static final String NOTIFY_SIGN_IN = "pref_key_notify_sign_in";
-	public static final String TOR_NETWORK = "pref_key_tor_network";
-	public static final String TOR_MOBILE = "pref_key_tor_mobile_data";
-	public static final String TOR_ONLY_WHEN_CHARGING =
+
+	private static final String TOR_NAMESPACE = TorConstants.ID.getString();
+	private static final String TOR_NETWORK = "pref_key_tor_network";
+	private static final String TOR_MOBILE = "pref_key_tor_mobile_data";
+	private static final String TOR_ONLY_WHEN_CHARGING =
 			"pref_key_tor_only_when_charging";
 
 	private static final Logger LOG =
@@ -122,7 +124,6 @@ public class SettingsFragment extends PreferenceFragmentCompat
 
 	private SettingsActivity listener;
 	private ListPreference language;
-	private ListPreference enableBluetooth;
 	private ListPreference torNetwork;
 	private SwitchPreference torMobile;
 	private SwitchPreference torOnlyWhenCharging;
@@ -137,7 +138,7 @@ public class SettingsFragment extends PreferenceFragmentCompat
 	private Preference notifySound;
 
 	// Fields that are accessed from background threads must be volatile
-	private volatile Settings settings, btSettings, torSettings;
+	private volatile Settings settings, torSettings;
 	private volatile boolean settingsLoaded = false;
 
 	@Inject
@@ -163,28 +164,20 @@ public class SettingsFragment extends PreferenceFragmentCompat
 	public void onCreatePreferences(Bundle bundle, String s) {
 		addPreferencesFromResource(R.xml.settings);
 
-		language = (ListPreference) findPreference(LANGUAGE);
+		language = findPreference(LANGUAGE);
 		setLanguageEntries();
-		ListPreference theme =
-				(ListPreference) findPreference("pref_key_theme");
-		enableBluetooth = (ListPreference) findPreference("pref_key_bluetooth");
-		torNetwork = (ListPreference) findPreference(TOR_NETWORK);
-		torMobile = (SwitchPreference) findPreference(TOR_MOBILE);
-		torOnlyWhenCharging =
-				(SwitchPreference) findPreference(TOR_ONLY_WHEN_CHARGING);
-		screenLock = (SwitchPreference) findPreference(PREF_SCREEN_LOCK);
-		screenLockTimeout =
-				(ListPreference) findPreference(PREF_SCREEN_LOCK_TIMEOUT);
-		notifyPrivateMessages = (SwitchPreference) findPreference(
-				"pref_key_notify_private_messages");
-		notifyGroupMessages = (SwitchPreference) findPreference(
-				"pref_key_notify_group_messages");
-		notifyForumPosts = (SwitchPreference) findPreference(
-				"pref_key_notify_forum_posts");
-		notifyBlogPosts = (SwitchPreference) findPreference(
-				"pref_key_notify_blog_posts");
-		notifyVibration = (SwitchPreference) findPreference(
-				"pref_key_notify_vibration");
+		ListPreference theme = findPreference("pref_key_theme");
+		torNetwork = findPreference(TOR_NETWORK);
+		torMobile = findPreference(TOR_MOBILE);
+		torOnlyWhenCharging = findPreference(TOR_ONLY_WHEN_CHARGING);
+		screenLock = findPreference(PREF_SCREEN_LOCK);
+		screenLockTimeout = findPreference(PREF_SCREEN_LOCK_TIMEOUT);
+		notifyPrivateMessages =
+				findPreference("pref_key_notify_private_messages");
+		notifyGroupMessages = findPreference("pref_key_notify_group_messages");
+		notifyForumPosts = findPreference("pref_key_notify_forum_posts");
+		notifyBlogPosts = findPreference("pref_key_notify_blog_posts");
+		notifyVibration = findPreference("pref_key_notify_vibration");
 		notifySound = findPreference("pref_key_notify_sound");
 
 		language.setOnPreferenceChangeListener(this);
@@ -194,8 +187,7 @@ public class SettingsFragment extends PreferenceFragmentCompat
 				UiUtils.setTheme(getActivity(), (String) newValue);
 				// bring up parent activity, so it can change its theme as well
 				// upstream bug: https://issuetracker.google.com/issues/38352704
-				Intent intent =
-						new Intent(getActivity(), ENTRY_ACTIVITY);
+				Intent intent = new Intent(getActivity(), ENTRY_ACTIVITY);
 				intent.setFlags(
 						FLAG_ACTIVITY_CLEAR_TASK | FLAG_ACTIVITY_NEW_TASK);
 				startActivity(intent);
@@ -206,7 +198,6 @@ public class SettingsFragment extends PreferenceFragmentCompat
 			}
 			return true;
 		});
-		enableBluetooth.setOnPreferenceChangeListener(this);
 		torNetwork.setOnPreferenceChangeListener(this);
 		torMobile.setOnPreferenceChangeListener(this);
 		torOnlyWhenCharging.setOnPreferenceChangeListener(this);
@@ -249,8 +240,9 @@ public class SettingsFragment extends PreferenceFragmentCompat
 	}
 
 	@Override
-	public View onCreateView(LayoutInflater inflater, ViewGroup container,
-			Bundle savedInstanceState) {
+	public View onCreateView(LayoutInflater inflater,
+			@Nullable ViewGroup container,
+			@Nullable Bundle savedInstanceState) {
 		View view = super.onCreateView(inflater, container, savedInstanceState);
 		ColorDrawable divider = new ColorDrawable(
 				ContextCompat.getColor(requireContext(), R.color.divider));
@@ -325,17 +317,13 @@ public class SettingsFragment extends PreferenceFragmentCompat
 
 		// Look up country name in the user's chosen language if available
 		String country = locationUtils.getCurrentCountry();
-		String countryName = country;
-		for (Locale locale : Locale.getAvailableLocales()) {
-			if (locale.getCountry().equalsIgnoreCase(country)) {
-				countryName = locale.getDisplayCountry();
-				break;
-			}
-		}
+		String countryName = getCountryDisplayName(country);
+
 		boolean blocked =
 				circumventionProvider.isTorProbablyBlocked(country);
 		boolean useBridges = circumventionProvider.doBridgesWork(country);
-		String setting = getString(R.string.tor_network_setting_without_bridges);
+		String setting =
+				getString(R.string.tor_network_setting_without_bridges);
 		if (blocked && useBridges) {
 			setting = getString(R.string.tor_network_setting_with_bridges);
 		} else if (blocked) {
@@ -351,8 +339,8 @@ public class SettingsFragment extends PreferenceFragmentCompat
 			try {
 				long start = now();
 				settings = settingsManager.getSettings(SETTINGS_NAMESPACE);
-				btSettings = settingsManager.getSettings(BT_NAMESPACE);
-				torSettings = settingsManager.getSettings(TOR_NAMESPACE);
+				torSettings = migrateTorSettings(
+						settingsManager.getSettings(TOR_NAMESPACE));
 				settingsLoaded = true;
 				logDuration(LOG, "Loading settings", start);
 				displaySettings();
@@ -362,15 +350,24 @@ public class SettingsFragment extends PreferenceFragmentCompat
 		});
 	}
 
+	// TODO: Remove after a reasonable migration period (added 2020-01-29)
+	private Settings migrateTorSettings(Settings s) {
+		int network = s.getInt(PREF_TOR_NETWORK, PREF_TOR_NETWORK_AUTOMATIC);
+		if (network == PREF_TOR_NETWORK_NEVER) {
+			s.putInt(PREF_TOR_NETWORK, PREF_TOR_NETWORK_AUTOMATIC);
+			s.putBoolean(PREF_PLUGIN_ENABLE, false);
+			// We don't need to save the migrated settings - the Tor plugin is
+			// responsible for that. This code just handles the case where the
+			// settings are loaded before the plugin migrates them.
+		}
+		return s;
+	}
+
 	private void displaySettings() {
 		listener.runOnUiThreadUnlessDestroyed(() -> {
 			// due to events, we might try to display before a load completed
 			if (!settingsLoaded) return;
 
-			boolean btEnabledSetting =
-					btSettings.getBoolean(PREF_BT_ENABLE, false);
-			enableBluetooth.setValue(Boolean.toString(btEnabledSetting));
-
 			int torNetworkSetting = torSettings.getInt(PREF_TOR_NETWORK,
 					PREF_TOR_NETWORK_AUTOMATIC);
 			torNetwork.setValue(Integer.toString(torNetworkSetting));
@@ -442,7 +439,6 @@ public class SettingsFragment extends PreferenceFragmentCompat
 		// preferences partly needed here, because they have their own logic
 		// - pref_key_lock (screenLock -> displayScreenLockSetting())
 		// - pref_key_lock_timeout (screenLockTimeout)
-		enableBluetooth.setEnabled(enabled);
 		torNetwork.setEnabled(enabled);
 		torMobile.setEnabled(enabled);
 		torOnlyWhenCharging.setEnabled(enabled);
@@ -544,9 +540,6 @@ public class SettingsFragment extends PreferenceFragmentCompat
 			if (!language.getValue().equals(newValue))
 				languageChanged((String) newValue);
 			return false;
-		} else if (preference == enableBluetooth) {
-			boolean btSetting = Boolean.valueOf((String) newValue);
-			storeBluetoothSettings(btSetting);
 		} else if (preference == torNetwork) {
 			int torNetworkSetting = Integer.valueOf((String) newValue);
 			storeTorNetworkSetting(torNetworkSetting);
@@ -628,12 +621,6 @@ public class SettingsFragment extends PreferenceFragmentCompat
 		mergeSettings(s, TOR_NAMESPACE);
 	}
 
-	private void storeBluetoothSettings(boolean btSetting) {
-		Settings s = new Settings();
-		s.putBoolean(PREF_BT_ENABLE, btSetting);
-		mergeSettings(s, BT_NAMESPACE);
-	}
-
 	private void storeSettings(Settings s) {
 		mergeSettings(s, SETTINGS_NAMESPACE);
 	}
@@ -692,13 +679,9 @@ public class SettingsFragment extends PreferenceFragmentCompat
 				LOG.info("Settings updated");
 				settings = s.getSettings();
 				displaySettings();
-			} else if (namespace.equals(BT_NAMESPACE)) {
-				LOG.info("Bluetooth settings updated");
-				btSettings = s.getSettings();
-				displaySettings();
 			} else if (namespace.equals(TOR_NAMESPACE)) {
 				LOG.info("Tor settings updated");
-				torSettings = s.getSettings();
+				torSettings = migrateTorSettings(s.getSettings());
 				displaySettings();
 			}
 		}

briar-android/src/main/java/org/briarproject/briar/android/util/UiUtils.java

@@ -6,6 +6,7 @@ import android.app.KeyguardManager;
 import android.content.Context;
 import android.content.DialogInterface.OnClickListener;
 import android.content.Intent;
+import android.graphics.drawable.Drawable;
 import android.net.Uri;
 import android.os.PowerManager;
 import android.text.Html;
@@ -38,9 +39,12 @@ import org.briarproject.briar.R;
 import org.briarproject.briar.android.view.ArticleMovementMethod;
 import org.briarproject.briar.android.widget.LinkDialogFragment;
 
+import java.util.Locale;
+
 import androidx.annotation.AttrRes;
 import androidx.annotation.ColorInt;
 import androidx.annotation.ColorRes;
+import androidx.annotation.DrawableRes;
 import androidx.annotation.Nullable;
 import androidx.annotation.RequiresApi;
 import androidx.annotation.UiThread;
@@ -79,7 +83,10 @@ import static androidx.appcompat.app.AppCompatDelegate.MODE_NIGHT_FOLLOW_SYSTEM;
 import static androidx.appcompat.app.AppCompatDelegate.MODE_NIGHT_NO;
 import static androidx.appcompat.app.AppCompatDelegate.MODE_NIGHT_YES;
 import static androidx.appcompat.app.AppCompatDelegate.setDefaultNightMode;
+import static androidx.core.content.ContextCompat.getColor;
+import static androidx.core.content.ContextCompat.getDrawable;
 import static androidx.core.content.ContextCompat.getSystemService;
+import static androidx.core.graphics.drawable.DrawableCompat.setTint;
 import static androidx.core.view.ViewCompat.LAYOUT_DIRECTION_RTL;
 import static java.util.Objects.requireNonNull;
 import static java.util.concurrent.TimeUnit.DAYS;
@@ -381,7 +388,7 @@ public class UiUtils {
 	/**
 	 * Same as {@link #observeOnce(LiveData, LifecycleOwner, Observer)},
 	 * but without a {@link LifecycleOwner}.
-	 *
+	 * <p>
 	 * Warning: Do NOT call from objects that have a lifecycle.
 	 */
 	@UiThread
@@ -402,4 +409,19 @@ public class UiUtils {
 				LAYOUT_DIRECTION_RTL;
 	}
 
+	public static String getCountryDisplayName(String isoCode) {
+		for (Locale locale : Locale.getAvailableLocales()) {
+			if (locale.getCountry().equalsIgnoreCase(isoCode)) {
+				return locale.getDisplayCountry();
+			}
+		}
+		// Name is unknown
+		return isoCode;
+	}
+
+	public static Drawable getDialogIcon(Context ctx, @DrawableRes int resId) {
+		Drawable icon = getDrawable(ctx, resId);
+		setTint(requireNonNull(icon), getColor(ctx, R.color.color_primary));
+		return icon;
+	}
 }

briar-android/src/main/java/org/briarproject/briar/android/widget/LinkDialogFragment.java

@@ -1,6 +1,7 @@
 package org.briarproject.briar.android.widget;
 
 
+import android.content.Context;
 import android.content.Intent;
 import android.content.pm.PackageManager;
 import android.net.Uri;
@@ -10,6 +11,7 @@ import android.view.View;
 import android.view.ViewGroup;
 import android.widget.Button;
 import android.widget.TextView;
+import android.widget.Toast;
 
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
@@ -22,6 +24,7 @@ import androidx.fragment.app.DialogFragment;
 
 import static android.content.Intent.ACTION_VIEW;
 import static android.content.pm.PackageManager.MATCH_DEFAULT_ONLY;
+import static android.widget.Toast.LENGTH_SHORT;
 import static java.util.Objects.requireNonNull;
 
 @MethodsNotNullByDefault
@@ -64,18 +67,23 @@ public class LinkDialogFragment extends DialogFragment {
 		urlView.setText(url);
 
 		// prepare normal intent or intent chooser
+		Context ctx = requireContext();
 		Intent i = new Intent(ACTION_VIEW, Uri.parse(url));
-		PackageManager packageManager =
-				requireNonNull(getContext()).getPackageManager();
-		List activities = packageManager.queryIntentActivities(i,
-				MATCH_DEFAULT_ONLY);
+		PackageManager packageManager = ctx.getPackageManager();
+		List activities =
+				packageManager.queryIntentActivities(i, MATCH_DEFAULT_ONLY);
 		boolean choice = activities.size() > 1;
 		Intent intent = choice ? Intent.createChooser(i,
 				getString(R.string.link_warning_open_link)) : i;
 
 		Button openButton = v.findViewById(R.id.openButton);
 		openButton.setOnClickListener(v1 -> {
-			startActivity(intent);
+			if (intent.resolveActivity(packageManager) != null) {
+				startActivity(intent);
+			} else {
+				Toast.makeText(ctx, R.string.error_start_activity, LENGTH_SHORT)
+						.show();
+			}
 			getDialog().dismiss();
 		});
 

briar-android/src/main/res/drawable/ic_baseline_drag_handle.xml

@@ -0,0 +1,12 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="24dp"
+    android:height="24dp"
+    android:viewportWidth="24"
+    android:viewportHeight="24">
+  <group>
+    <path
+        android:fillColor="#000000"
+        android:pathData="M20,9H4v2h16V9zM4,15h16v-2H4v2z" />
+  </group>
+</vector>
+

briar-android/src/main/res/drawable/ic_image_broken.xml

@@ -1,6 +1,6 @@
 <vector xmlns:android="http://schemas.android.com/apk/res/android"
-        android:width="115dp"
-        android:height="115dp"
+        android:width="200dp"
+        android:height="200dp"
         android:viewportHeight="24.0"
         android:viewportWidth="24.0">
 	<path

briar-android/src/main/res/drawable/ic_image_missing.xml

@@ -1,10 +0,0 @@
-<vector
-	xmlns:android="http://schemas.android.com/apk/res/android"
-	android:width="115dp"
-	android:height="115dp"
-	android:viewportHeight="24.0"
-	android:viewportWidth="24.0">
-	<path
-		android:fillColor="#808080"
-		android:pathData="M21,19V5c0,-1.1 -0.9,-2 -2,-2H5c-1.1,0 -2,0.9 -2,2v14c0,1.1 0.9,2 2,2h14c1.1,0 2,-0.9 2,-2zM8.5,13.5l2.5,3.01L14.5,12l4.5,6H5l3.5,-4.5z"/>
-</vector>

briar-android/src/main/res/layout/navigation_menu.xml

@@ -1,59 +1,12 @@
 <?xml version="1.0" encoding="utf-8"?>
 <ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
-	xmlns:app="http://schemas.android.com/apk/res-auto"
-	xmlns:tools="http://schemas.android.com/tools"
+	android:id="@+id/drawerScrollView"
 	android:layout_width="wrap_content"
 	android:layout_height="match_parent"
 	android:background="@color/window_background"
 	android:fillViewport="true"
 	android:orientation="vertical">
 
-	<androidx.constraintlayout.widget.ConstraintLayout
-		android:layout_width="wrap_content"
-		android:layout_height="wrap_content">
+	<include layout="@layout/navigation_menu_collapsed" />
 
-		<com.google.android.material.navigation.NavigationView
-			android:id="@+id/navigation"
-			android:layout_width="wrap_content"
-			android:layout_height="wrap_content"
-			android:background="@color/window_background"
-			app:elevation="0dp"
-			app:headerLayout="@layout/navigation_header"
-			app:itemBackground="@drawable/navigation_item_background"
-			app:itemIconTint="?attr/colorControlNormal"
-			app:itemTextColor="?android:textColorPrimary"
-			app:layout_constraintStart_toStartOf="parent"
-			app:layout_constraintTop_toTopOf="parent"
-			app:menu="@menu/navigation_drawer" />
-
-		<View
-			android:id="@+id/divider1"
-			style="@style/Divider.Horizontal"
-			android:layout_width="0dp"
-			app:layout_constraintEnd_toEndOf="@+id/navigation"
-			app:layout_constraintStart_toStartOf="parent"
-			app:layout_constraintTop_toBottomOf="@+id/navigation" />
-
-		<View
-			android:id="@+id/spacer"
-			android:layout_width="0dp"
-			android:layout_height="0dp"
-			app:layout_constraintBottom_toTopOf="@+id/transports"
-			app:layout_constraintStart_toStartOf="parent"
-			app:layout_constraintTop_toBottomOf="@+id/divider1"
-			app:layout_constraintVertical_weight="1" />
-
-		<include
-			android:id="@+id/transports"
-			layout="@layout/transports_list"
-			android:layout_width="0dp"
-			android:layout_height="wrap_content"
-			app:layout_constraintBottom_toBottomOf="parent"
-			app:layout_constraintEnd_toEndOf="@+id/navigation"
-			app:layout_constraintStart_toStartOf="parent"
-			app:layout_constraintTop_toBottomOf="@+id/spacer"
-			tools:layout_height="75dp" />
-
-	</androidx.constraintlayout.widget.ConstraintLayout>
-
-</ScrollView>
+</ScrollView>

briar-android/src/main/res/layout/navigation_menu_collapsed.xml

@@ -0,0 +1,165 @@
+<?xml version="1.0" encoding="utf-8"?>
+<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+	xmlns:app="http://schemas.android.com/apk/res-auto"
+	xmlns:tools="http://schemas.android.com/tools"
+	android:id="@+id/drawerContent"
+	android:layout_width="wrap_content"
+	android:layout_height="wrap_content"
+	android:background="@color/window_background">
+
+	<com.google.android.material.navigation.NavigationView
+		android:id="@+id/navigation"
+		android:layout_width="wrap_content"
+		android:layout_height="wrap_content"
+		android:background="@color/window_background"
+		app:elevation="0dp"
+		app:headerLayout="@layout/navigation_header"
+		app:itemBackground="@drawable/navigation_item_background"
+		app:itemIconTint="?attr/colorControlNormal"
+		app:itemTextColor="?android:textColorPrimary"
+		app:layout_constraintStart_toStartOf="parent"
+		app:layout_constraintTop_toTopOf="parent"
+		app:layout_constraintVertical_bias="0.0"
+		app:menu="@menu/navigation_drawer" />
+
+	<androidx.appcompat.widget.AppCompatImageButton
+		android:id="@+id/chevronView"
+		android:layout_width="0dp"
+		android:layout_height="24dp"
+		android:layout_marginBottom="8dp"
+		android:background="@color/divider"
+		android:foreground="?attr/selectableItemBackground"
+		android:src="@drawable/chevron_up_white"
+		app:layout_constraintBottom_toTopOf="@+id/connectionsLabel"
+		app:layout_constraintEnd_toEndOf="parent"
+		app:layout_constraintStart_toStartOf="parent"
+		app:layout_constraintTop_toBottomOf="@+id/navigation"
+		app:layout_constraintVertical_bias="1.0"
+		app:layout_constraintVertical_chainStyle="packed"
+		app:tint="?attr/colorControlNormal"
+		tools:ignore="ContentDescription,UnusedAttribute" />
+
+	<View
+		android:id="@+id/connectionsBackground"
+		android:layout_width="0dp"
+		android:layout_height="0dp"
+		app:layout_constraintBottom_toBottomOf="parent"
+		app:layout_constraintEnd_toEndOf="parent"
+		app:layout_constraintStart_toStartOf="parent"
+		app:layout_constraintTop_toBottomOf="@+id/chevronView" />
+
+	<TextView
+		android:id="@+id/connectionsLabel"
+		android:layout_width="wrap_content"
+		android:layout_height="wrap_content"
+		android:layout_marginStart="16dp"
+		android:layout_marginLeft="16dp"
+		android:layout_marginTop="8dp"
+		android:layout_marginBottom="16dp"
+		android:text="@string/transport_connection"
+		android:textSize="12sp"
+		android:visibility="visible"
+		app:layout_constraintBottom_toBottomOf="parent"
+		app:layout_constraintEnd_toStartOf="@+id/torIcon"
+		app:layout_constraintHorizontal_bias="0.0"
+		app:layout_constraintStart_toStartOf="parent"
+		app:layout_constraintTop_toBottomOf="@+id/chevronView" />
+
+	<!-- Hidden -->
+	<View
+		android:id="@+id/longRangeBackground"
+		android:layout_width="0dp"
+		android:layout_height="0dp"
+		android:background="@color/item_background_highlight"
+		android:visibility="gone"
+		tools:ignore="MissingConstraints" />
+
+	<!-- Hidden -->
+	<TextView
+		android:id="@+id/longRangeLabel"
+		android:layout_width="0dp"
+		android:layout_height="0dp"
+		android:text="@string/transport_internet"
+		android:textSize="12sp"
+		android:visibility="gone"
+		tools:ignore="MissingConstraints" />
+
+	<ImageView
+		android:id="@+id/torIcon"
+		android:layout_width="wrap_content"
+		android:layout_height="wrap_content"
+		android:layout_marginEnd="16dp"
+		android:layout_marginRight="16dp"
+		android:src="@drawable/transport_tor"
+		app:layout_constraintBottom_toBottomOf="parent"
+		app:layout_constraintEnd_toStartOf="@+id/wifiIcon"
+		app:layout_constraintTop_toBottomOf="@+id/chevronView"
+		tools:ignore="ContentDescription"
+		tools:tint="@color/briar_green" />
+
+	<!-- Hidden -->
+	<androidx.appcompat.widget.SwitchCompat
+		android:id="@+id/torSwitch"
+		android:layout_width="0dp"
+		android:layout_height="0dp"
+		android:text="@string/transport_tor"
+		android:visibility="gone"
+		tools:ignore="MissingConstraints" />
+
+	<!-- Hidden -->
+	<TextView
+		android:id="@+id/nearbyLabel"
+		android:layout_width="0dp"
+		android:layout_height="0dp"
+		android:text="@string/transport_nearby"
+		android:textSize="12sp"
+		android:visibility="gone"
+		tools:ignore="MissingConstraints" />
+
+	<ImageView
+		android:id="@+id/wifiIcon"
+		android:layout_width="wrap_content"
+		android:layout_height="wrap_content"
+		android:layout_marginEnd="16dp"
+		android:layout_marginRight="16dp"
+		android:src="@drawable/transport_lan"
+		app:layout_constraintBottom_toBottomOf="parent"
+		app:layout_constraintEnd_toStartOf="@+id/btIcon"
+		app:layout_constraintTop_toBottomOf="@+id/chevronView"
+		tools:checked="true"
+		tools:ignore="ContentDescription"
+		tools:tint="@color/briar_green" />
+
+	<!-- Hidden -->
+	<androidx.appcompat.widget.SwitchCompat
+		android:id="@+id/wifiSwitch"
+		android:layout_width="0dp"
+		android:layout_height="0dp"
+		android:text="@string/transport_lan"
+		android:visibility="gone"
+		tools:ignore="MissingConstraints" />
+
+	<ImageView
+		android:id="@+id/btIcon"
+		android:layout_width="wrap_content"
+		android:layout_height="wrap_content"
+		android:layout_marginEnd="16dp"
+		android:layout_marginRight="16dp"
+		android:src="@drawable/transport_bt"
+		app:layout_constraintBottom_toBottomOf="parent"
+		app:layout_constraintEnd_toEndOf="parent"
+		app:layout_constraintTop_toBottomOf="@+id/chevronView"
+		tools:checked="true"
+		tools:ignore="ContentDescription"
+		tools:tint="@color/briar_green" />
+
+	<!-- Hidden -->
+	<androidx.appcompat.widget.SwitchCompat
+		android:id="@+id/btSwitch"
+		android:layout_width="0dp"
+		android:layout_height="0dp"
+		android:text="@string/transport_bt"
+		android:visibility="gone"
+		tools:ignore="MissingConstraints" />
+
+</androidx.constraintlayout.widget.ConstraintLayout>

briar-android/src/main/res/layout/navigation_menu_expanded.xml

@@ -0,0 +1,183 @@
+<?xml version="1.0" encoding="utf-8"?>
+<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+	xmlns:app="http://schemas.android.com/apk/res-auto"
+	xmlns:tools="http://schemas.android.com/tools"
+	android:id="@+id/drawerContent"
+	android:layout_width="wrap_content"
+	android:layout_height="wrap_content"
+	android:background="@color/window_background">
+
+	<com.google.android.material.navigation.NavigationView
+		android:id="@+id/navigation"
+		android:layout_width="wrap_content"
+		android:layout_height="wrap_content"
+		android:background="@color/window_background"
+		app:elevation="0dp"
+		app:headerLayout="@layout/navigation_header"
+		app:itemBackground="@drawable/navigation_item_background"
+		app:itemIconTint="?attr/colorControlNormal"
+		app:itemTextColor="?android:textColorPrimary"
+		app:layout_constraintStart_toStartOf="parent"
+		app:layout_constraintTop_toTopOf="parent"
+		app:layout_constraintVertical_bias="0.0"
+		app:menu="@menu/navigation_drawer" />
+
+	<androidx.appcompat.widget.AppCompatImageButton
+		android:id="@+id/chevronView"
+		android:layout_width="0dp"
+		android:layout_height="24dp"
+		android:layout_marginBottom="8dp"
+		android:background="@color/divider"
+		android:foreground="?attr/selectableItemBackground"
+		android:src="@drawable/chevron_down_white"
+		app:layout_constraintBottom_toTopOf="@+id/longRangeLabel"
+		app:layout_constraintEnd_toEndOf="parent"
+		app:layout_constraintStart_toStartOf="parent"
+		app:layout_constraintTop_toBottomOf="@+id/navigation"
+		app:layout_constraintVertical_bias="1.0"
+		app:layout_constraintVertical_chainStyle="packed"
+		app:tint="?attr/colorControlNormal"
+		tools:ignore="ContentDescription,UnusedAttribute" />
+
+	<!-- Hidden -->
+	<View
+		android:id="@+id/connectionsBackground"
+		android:layout_width="0dp"
+		android:layout_height="0dp"
+		android:visibility="gone"
+		tools:ignore="MissingConstraints" />
+
+	<!-- Hidden -->
+	<TextView
+		android:id="@+id/connectionsLabel"
+		android:layout_width="0dp"
+		android:layout_height="0dp"
+		android:text="@string/transport_connection"
+		android:textSize="12sp"
+		android:visibility="gone"
+		tools:ignore="MissingConstraints" />
+
+	<View
+		android:id="@+id/longRangeBackground"
+		android:layout_width="0dp"
+		android:layout_height="0dp"
+		android:layout_marginBottom="8dp"
+		android:background="@color/item_background_highlight"
+		app:layout_constraintBottom_toTopOf="@+id/nearbyLabel"
+		app:layout_constraintEnd_toEndOf="parent"
+		app:layout_constraintStart_toStartOf="parent"
+		app:layout_constraintTop_toBottomOf="@+id/chevronView" />
+
+	<TextView
+		android:id="@+id/longRangeLabel"
+		android:layout_width="wrap_content"
+		android:layout_height="wrap_content"
+		android:layout_marginBottom="8dp"
+		android:text="@string/transport_internet"
+		android:textSize="12sp"
+		app:layout_constraintBottom_toTopOf="@+id/torSwitch"
+		app:layout_constraintStart_toStartOf="@+id/torIcon"
+		app:layout_constraintTop_toBottomOf="@+id/chevronView" />
+
+	<ImageView
+		android:id="@+id/torIcon"
+		android:layout_width="wrap_content"
+		android:layout_height="wrap_content"
+		android:layout_marginStart="16dp"
+		android:layout_marginLeft="16dp"
+		android:src="@drawable/transport_tor"
+		app:layout_constraintBottom_toBottomOf="@+id/torSwitch"
+		app:layout_constraintStart_toStartOf="parent"
+		app:layout_constraintTop_toTopOf="@+id/torSwitch"
+		tools:ignore="ContentDescription"
+		tools:tint="@color/briar_green" />
+
+	<androidx.appcompat.widget.SwitchCompat
+		android:id="@+id/torSwitch"
+		android:layout_width="0dp"
+		android:layout_height="wrap_content"
+		android:layout_marginStart="16dp"
+		android:layout_marginLeft="16dp"
+		android:layout_marginEnd="16dp"
+		android:layout_marginRight="16dp"
+		android:layout_marginBottom="16dp"
+		android:text="@string/transport_tor"
+		app:layout_constraintBottom_toTopOf="@+id/nearbyLabel"
+		app:layout_constraintEnd_toEndOf="parent"
+		app:layout_constraintStart_toEndOf="@+id/torIcon"
+		app:layout_constraintTop_toBottomOf="@+id/longRangeLabel"
+		tools:checked="true" />
+
+	<TextView
+		android:id="@+id/nearbyLabel"
+		android:layout_width="wrap_content"
+		android:layout_height="wrap_content"
+		android:layout_marginBottom="8dp"
+		android:gravity="center_vertical"
+		android:text="@string/transport_nearby"
+		android:textSize="12sp"
+		app:layout_constraintBottom_toTopOf="@+id/wifiSwitch"
+		app:layout_constraintStart_toStartOf="@+id/torIcon"
+		app:layout_constraintTop_toBottomOf="@+id/torSwitch" />
+
+	<ImageView
+		android:id="@+id/wifiIcon"
+		android:layout_width="wrap_content"
+		android:layout_height="wrap_content"
+		android:layout_marginStart="16dp"
+		android:layout_marginLeft="16dp"
+		android:src="@drawable/transport_lan"
+		app:layout_constraintBottom_toBottomOf="@+id/wifiSwitch"
+		app:layout_constraintStart_toStartOf="parent"
+		app:layout_constraintTop_toTopOf="@+id/wifiSwitch"
+		tools:checked="true"
+		tools:ignore="ContentDescription"
+		tools:tint="@color/briar_green" />
+
+	<androidx.appcompat.widget.SwitchCompat
+		android:id="@+id/wifiSwitch"
+		android:layout_width="0dp"
+		android:layout_height="wrap_content"
+		android:layout_marginStart="16dp"
+		android:layout_marginLeft="16dp"
+		android:layout_marginEnd="16dp"
+		android:layout_marginRight="16dp"
+		android:layout_marginBottom="8dp"
+		android:text="@string/transport_lan"
+		app:layout_constraintBottom_toTopOf="@+id/btSwitch"
+		app:layout_constraintEnd_toEndOf="parent"
+		app:layout_constraintStart_toEndOf="@+id/wifiIcon"
+		app:layout_constraintTop_toBottomOf="@+id/nearbyLabel"
+		tools:checked="true" />
+
+	<ImageView
+		android:id="@+id/btIcon"
+		android:layout_width="wrap_content"
+		android:layout_height="wrap_content"
+		android:layout_marginStart="16dp"
+		android:layout_marginLeft="16dp"
+		android:src="@drawable/transport_bt"
+		app:layout_constraintBottom_toBottomOf="@+id/btSwitch"
+		app:layout_constraintStart_toStartOf="parent"
+		app:layout_constraintTop_toTopOf="@+id/btSwitch"
+		tools:checked="true"
+		tools:ignore="ContentDescription"
+		tools:tint="@color/briar_green" />
+
+	<androidx.appcompat.widget.SwitchCompat
+		android:id="@+id/btSwitch"
+		android:layout_width="0dp"
+		android:layout_height="wrap_content"
+		android:layout_marginStart="16dp"
+		android:layout_marginLeft="16dp"
+		android:layout_marginEnd="16dp"
+		android:layout_marginRight="16dp"
+		android:layout_marginBottom="8dp"
+		android:text="@string/transport_bt"
+		app:layout_constraintBottom_toBottomOf="parent"
+		app:layout_constraintEnd_toEndOf="parent"
+		app:layout_constraintStart_toEndOf="@+id/btIcon"
+		app:layout_constraintTop_toBottomOf="@+id/wifiSwitch"
+		tools:checked="true" />
+
+</androidx.constraintlayout.widget.ConstraintLayout>

briar-android/src/main/res/layout/transports_list.xml

@@ -1,19 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
-	xmlns:tools="http://schemas.android.com/tools"
-	android:layout_width="match_parent"
-	android:layout_height="wrap_content"
-	android:orientation="vertical"
-	tools:showIn="@layout/navigation_menu">
-
-	<View style="@style/Divider.Horizontal" />
-
-	<GridView
-		android:id="@+id/transportsView"
-		android:layout_width="match_parent"
-		android:layout_height="wrap_content"
-		android:listSelector="@android:color/transparent"
-		android:numColumns="3"
-		tools:listitem="@layout/list_item_transport" />
-
-</LinearLayout>

briar-android/src/main/res/menu/navigation_drawer.xml

@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
-<menu
-	xmlns:android="http://schemas.android.com/apk/res/android">
+<menu xmlns:android="http://schemas.android.com/apk/res/android"
+	xmlns:tools="http://schemas.android.com/tools">
 
 	<group android:checkableBehavior="single">
 		<item
@@ -30,7 +30,8 @@
 			android:id="@+id/nav_btn_lock"
 			android:icon="@drawable/startup_lock"
 			android:title="@string/lock_button"
-			android:visible="false"/>
+			android:visible="false"
+			tools:visible="false" />
 		<item
 			android:id="@+id/nav_btn_signout"
 			android:icon="@drawable/ic_signout"

briar-android/src/main/res/values-de/strings.xml

@@ -1,5 +1,5 @@
 <?xml version='1.0' encoding='UTF-8'?>
-<resources>
+<resources xmlns:tools="http://schemas.android.com/tools">
   <!--Setup-->
   <string name="setup_title">Willkommen bei Briar</string>
   <string name="setup_name_explanation">Dein Benutzername wird neben deinem geposteten Inhalt angezeigt. Du kannst diesen nicht mehr ändern, nachdem du dein Konto erstellt hast.</string>

briar-android/src/main/res/values-es/strings.xml

@@ -125,9 +125,16 @@
   <string name="set_contact_alias_hint">Nombre del contacto</string>
   <string name="set_alias_button">Cambiar</string>
   <string name="delete_all_messages">Eliminar todos los mensajes</string>
-  <string name="dialog_title_delete_all_messages">Confirmar la eliminación del mensaje</string>
+  <string name="dialog_title_delete_all_messages">Confirmar eliminación de mensajes</string>
   <string name="dialog_message_delete_all_messages">¿Estás seguro de que deseas eliminar todos los mensajes?</string>
   <string name="dialog_title_not_all_messages_deleted">No se pudieron eliminar todos los mensajes.</string>
+  <string name="dialog_message_not_deleted_ongoing_both">Los mensajes relacionados con presentaciones o invitaciones en curso no se pueden eliminar hasta que finalicen.</string>
+  <string name="dialog_message_not_deleted_ongoing_introductions">Los mensajes relacionados con presentaciones o invitaciones en curso no se pueden eliminar hasta que finalicen.</string>
+  <string name="dialog_message_not_deleted_ongoing_invitations">Los mensajes relacionados a invitaciones en curso no pueden ser borrados hasta su conclusión.</string>
+  <string name="dialog_message_not_deleted_partly_downloaded">Los mensajes parcialmente descargados no se pueden eliminar hasta que haya finalizado la descarga.</string>
+  <string name="dialog_message_not_deleted_not_all_selected_both">Para borrar una invitación o presentación, debes seleccionar la petición y la respuesta.</string>
+  <string name="dialog_message_not_deleted_not_all_selected_introductions">Para eliminar una introducción, debe seleccionar la solicitud y la respuesta.</string>
+  <string name="dialog_message_not_deleted_not_all_selected_invitations">Para eliminar una invitación, debe seleccionar la solicitud y la respuesta.</string>
   <string name="delete_contact">Eliminar contacto</string>
   <string name="dialog_title_delete_contact">Confirmar eliminación de contacto</string>
   <string name="dialog_message_delete_contact">¿Seguro que quieres eliminar este contacto y todos los mensajes intercambiados entre vosotros?</string>

briar-android/src/main/res/values-he/strings.xml

@@ -1,5 +1,5 @@
 <?xml version='1.0' encoding='UTF-8'?>
-<resources>
+<resources xmlns:tools="http://schemas.android.com/tools">
   <!--Setup-->
   <string name="setup_title">ברוך הבא אל Briar</string>
   <string name="setup_name_explanation">כינויך יוראה ליד תוכן כלשהו שתכתוב. אינך יכול לשנות אותו לאחר יצירת חשבונך.</string>

briar-android/src/main/res/values-is/strings.xml

@@ -128,6 +128,13 @@
   <string name="dialog_title_delete_all_messages">Staðfesta eyðingu skilaboða</string>
   <string name="dialog_message_delete_all_messages">Ertu viss um að þú viljir eyða öllum skilaboðum?</string>
   <string name="dialog_title_not_all_messages_deleted">Gat ekki eytt öllum skilaboðum</string>
+  <string name="dialog_message_not_deleted_ongoing_both">Skilaboð sem tengjast fyrirliggjandi kynningum fyrirliggjandi boðum og kynningum er ekki hægt að eyða fyrr en viðkomandi ferli er lokið.</string>
+  <string name="dialog_message_not_deleted_ongoing_introductions">Skilaboð sem tengjast fyrirliggjandi kynningum fyrirliggjandi kynningum er ekki hægt að eyða fyrr en viðkomandi ferli er lokið.</string>
+  <string name="dialog_message_not_deleted_ongoing_invitations">Skilaboð sem tengjast fyrirliggjandi kynningum fyrirliggjandi boðum er ekki hægt að eyða fyrr en viðkomandi ferli er lokið.</string>
+  <string name="dialog_message_not_deleted_partly_downloaded">Skilaboðum sem sótt hafa verið að hluta er ekki hægt að eyða fyrr en niðurhali þeirra er lokið.</string>
+  <string name="dialog_message_not_deleted_not_all_selected_both">Til að eyða boði eða kynningu, þarftu að velja beiðnina og svarið.</string>
+  <string name="dialog_message_not_deleted_not_all_selected_introductions">Til að eyða kynningu, þarftu að velja beiðnina og svarið.</string>
+  <string name="dialog_message_not_deleted_not_all_selected_invitations">Til að eyða boði, þarftu að velja beiðnina og svarið.</string>
   <string name="delete_contact">Eyða tengilið</string>
   <string name="dialog_title_delete_contact">Staðfesta eyðingu tengiliðar</string>
   <string name="dialog_message_delete_contact">Ertu viss að þú viljir fjarlægja þennan tengilið ásamt öllum þeim skilaboðum sem ykkur hafa farið á milli?</string>

briar-android/src/main/res/values-lt/strings.xml

@@ -1,5 +1,5 @@
 <?xml version='1.0' encoding='UTF-8'?>
-<resources>
+<resources xmlns:tools="http://schemas.android.com/tools">
   <!--Setup-->
   <string name="setup_title">Sveiki atvykę į Briar</string>
   <string name="setup_name_explanation">Jūsų slapyvardis bus rodomas šalia bet kokio jūsų skelbiamo turinio. Sukūrę paskyrą, slapyvardžio pakeisti nebegalėsite.</string>

briar-android/src/main/res/values-nl/strings.xml

@@ -128,6 +128,13 @@
   <string name="dialog_title_delete_all_messages">Bevestig verwijderen berichten</string>
   <string name="dialog_message_delete_all_messages">Weet je zeker dat je alle berichten wil verwijderen?</string>
   <string name="dialog_title_not_all_messages_deleted">Kon niet alle berichten verwijderen</string>
+  <string name="dialog_message_not_deleted_ongoing_both">Berichten gerelateerd aan uitgaande uitnodigingen of introducties kunnen niet worden verwijderd totdat ze zijn afgerond.</string>
+  <string name="dialog_message_not_deleted_ongoing_introductions">Berichten gerelateerd aan uitgaande introducties kunnen niet worden verwijderd totdat ze zijn afgerond.</string>
+  <string name="dialog_message_not_deleted_ongoing_invitations">Berichten gerelateerd aan uitgaande uitnodigingen kunnen niet worden verwijderd totdat ze zijn afgerond.</string>
+  <string name="dialog_message_not_deleted_partly_downloaded">Gedeeltelijk gedownloade berichten kunnen niet worden verwijderd totdat ze volledig zijn gedownload.</string>
+  <string name="dialog_message_not_deleted_not_all_selected_both">Om een uitnodiging of introductie te verwijderen met je het verzoek en het antwoord selecteren.</string>
+  <string name="dialog_message_not_deleted_not_all_selected_introductions">Om een introductie te verwijderen met je het verzoek en het antwoord selecteren.</string>
+  <string name="dialog_message_not_deleted_not_all_selected_invitations">Om een uitnodiging te verwijderen met je het verzoek en het antwoord selecteren.</string>
   <string name="delete_contact">Verwijder bericht</string>
   <string name="dialog_title_delete_contact">Bevestig verwijderen contact</string>
   <string name="dialog_message_delete_contact">Weet je zeker dat je dit contact en alle berichten die met dit contact zijn uitgewisseld wil verwijderen?</string>