Refactor key agreement connection choosing.

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

@@ -21,6 +21,8 @@ import org.briarproject.bramble.util.AndroidUtils;
 import java.io.Closeable;
 import java.io.IOException;
 import java.security.SecureRandom;
+import java.util.ArrayList;
+import java.util.List;
 import java.util.UUID;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.Executor;
@@ -37,7 +39,16 @@ import static android.bluetooth.BluetoothAdapter.SCAN_MODE_CONNECTABLE_DISCOVERA
 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_BOND_STATE_CHANGED;
+import static android.bluetooth.BluetoothDevice.BOND_BONDED;
+import static android.bluetooth.BluetoothDevice.BOND_BONDING;
+import static android.bluetooth.BluetoothDevice.BOND_NONE;
+import static android.bluetooth.BluetoothDevice.EXTRA_BOND_STATE;
+import static android.bluetooth.BluetoothDevice.EXTRA_DEVICE;
+import static android.bluetooth.BluetoothDevice.EXTRA_PREVIOUS_BOND_STATE;
+import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
+import static org.briarproject.bramble.util.PrivacyUtils.scrubMacAddress;
 
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
@@ -55,10 +66,12 @@ class AndroidBluetoothPlugin extends BluetoothPlugin<BluetoothServerSocket> {
 	// Non-null if the plugin started successfully
 	private volatile BluetoothAdapter adapter = null;
 
-	AndroidBluetoothPlugin(Executor ioExecutor, AndroidExecutor androidExecutor,
+	AndroidBluetoothPlugin(BluetoothConnectionManager connectionManager,
+			Executor ioExecutor, AndroidExecutor androidExecutor,
 			Context appContext, SecureRandom secureRandom, Backoff backoff,
 			DuplexPluginCallback callback, int maxLatency) {
-		super(ioExecutor, secureRandom, backoff, callback, maxLatency);
+		super(connectionManager, ioExecutor, secureRandom, backoff, callback,
+				maxLatency);
 		this.androidExecutor = androidExecutor;
 		this.appContext = appContext;
 	}
@@ -70,6 +83,7 @@ class AndroidBluetoothPlugin extends BluetoothPlugin<BluetoothServerSocket> {
 		IntentFilter filter = new IntentFilter();
 		filter.addAction(ACTION_STATE_CHANGED);
 		filter.addAction(ACTION_SCAN_MODE_CHANGED);
+		filter.addAction(ACTION_BOND_STATE_CHANGED);
 		receiver = new BluetoothStateReceiver();
 		appContext.registerReceiver(receiver, filter);
 	}
@@ -154,7 +168,8 @@ class AndroidBluetoothPlugin extends BluetoothPlugin<BluetoothServerSocket> {
 	}
 
 	private DuplexTransportConnection wrapSocket(BluetoothSocket s) {
-		return new AndroidBluetoothTransportConnection(this, s);
+		return new AndroidBluetoothTransportConnection(this,
+				connectionManager, s);
 	}
 
 	@Override
@@ -165,6 +180,17 @@ class AndroidBluetoothPlugin extends BluetoothPlugin<BluetoothServerSocket> {
 	@Override
 	DuplexTransportConnection connectTo(String address, String uuid)
 			throws IOException {
+		if (LOG.isLoggable(INFO)) {
+			boolean found = false;
+			List<String> addresses = new ArrayList<>();
+			for (BluetoothDevice d : adapter.getBondedDevices()) {
+				addresses.add(scrubMacAddress(d.getAddress()));
+				if (d.getAddress().equals(address)) found = true;
+			}
+			LOG.info("Bonded devices: " + addresses);
+			if (found) LOG.info("Connecting to bonded device");
+			else LOG.info("Connecting to unbonded device");
+		}
 		BluetoothDevice d = adapter.getRemoteDevice(address);
 		UUID u = UUID.fromString(uuid);
 		BluetoothSocket s = null;
@@ -190,16 +216,42 @@ class AndroidBluetoothPlugin extends BluetoothPlugin<BluetoothServerSocket> {
 
 		@Override
 		public void onReceive(Context ctx, Intent intent) {
-			int state = intent.getIntExtra(EXTRA_STATE, 0);
-			if (state == STATE_ON) onAdapterEnabled();
-			else if (state == STATE_OFF) onAdapterDisabled();
-			int scanMode = intent.getIntExtra(EXTRA_SCAN_MODE, 0);
-			if (scanMode == SCAN_MODE_NONE) {
-				LOG.info("Scan mode: None");
-			} else if (scanMode == SCAN_MODE_CONNECTABLE) {
-				LOG.info("Scan mode: Connectable");
-			} else if (scanMode == SCAN_MODE_CONNECTABLE_DISCOVERABLE) {
-				LOG.info("Scan mode: Discoverable");
+			String action = intent.getAction();
+			if (ACTION_STATE_CHANGED.equals(action)) {
+				int state = intent.getIntExtra(EXTRA_STATE, 0);
+				if (state == STATE_ON) onAdapterEnabled();
+				else if (state == STATE_OFF) onAdapterDisabled();
+			} else if (ACTION_SCAN_MODE_CHANGED.equals(action)) {
+				int scanMode = intent.getIntExtra(EXTRA_SCAN_MODE, 0);
+				if (scanMode == SCAN_MODE_NONE) {
+					LOG.info("Scan mode: None");
+				} else if (scanMode == SCAN_MODE_CONNECTABLE) {
+					LOG.info("Scan mode: Connectable");
+				} else if (scanMode == SCAN_MODE_CONNECTABLE_DISCOVERABLE) {
+					LOG.info("Scan mode: Discoverable");
+				}
+			} else if (ACTION_BOND_STATE_CHANGED.equals(action)) {
+				BluetoothDevice d = intent.getParcelableExtra(EXTRA_DEVICE);
+				if (LOG.isLoggable(INFO)) {
+					LOG.info("Bond state changed for "
+							+ scrubMacAddress(d.getAddress()));
+				}
+				int oldState = intent.getIntExtra(EXTRA_PREVIOUS_BOND_STATE, 0);
+				if (oldState == BOND_NONE) {
+					LOG.info("Old state: none");
+				} else if (oldState == BOND_BONDING) {
+					LOG.info("Old state: bonding");
+				} else if (oldState == BOND_BONDED) {
+					LOG.info("Old state: bonded");
+				}
+				int state = intent.getIntExtra(EXTRA_BOND_STATE, 0);
+				if (state == BOND_NONE) {
+					LOG.info("New state: none");
+				} else if (state == BOND_BONDING) {
+					LOG.info("New state: bonding");
+				} else if (state == BOND_BONDED) {
+					LOG.info("New state: bonded");
+				}
 			}
 		}
 	}

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

@@ -59,11 +59,13 @@ public class AndroidBluetoothPluginFactory implements DuplexPluginFactory {
 
 	@Override
 	public DuplexPlugin createPlugin(DuplexPluginCallback callback) {
+		BluetoothConnectionManager connectionManager =
+				new BluetoothConnectionManagerImpl();
 		Backoff backoff = backoffFactory.createBackoff(MIN_POLLING_INTERVAL,
 				MAX_POLLING_INTERVAL, BACKOFF_BASE);
-		AndroidBluetoothPlugin plugin = new AndroidBluetoothPlugin(ioExecutor,
-				androidExecutor, appContext, secureRandom, backoff, callback,
-				MAX_LATENCY);
+		AndroidBluetoothPlugin plugin = new AndroidBluetoothPlugin(
+				connectionManager, ioExecutor, androidExecutor, appContext,
+				secureRandom, backoff, callback, MAX_LATENCY);
 		eventBus.addListener(plugin);
 		return plugin;
 	}

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

@@ -14,10 +14,14 @@ import java.io.OutputStream;
 class AndroidBluetoothTransportConnection
 		extends AbstractDuplexTransportConnection {
 
+	private final BluetoothConnectionManager connectionManager;
 	private final BluetoothSocket socket;
 
-	AndroidBluetoothTransportConnection(Plugin plugin, BluetoothSocket socket) {
+	AndroidBluetoothTransportConnection(Plugin plugin,
+			BluetoothConnectionManager connectionManager,
+			BluetoothSocket socket) {
 		super(plugin);
+		this.connectionManager = connectionManager;
 		this.socket = socket;
 	}
 
@@ -33,6 +37,10 @@ class AndroidBluetoothTransportConnection
 
 	@Override
 	protected void closeConnection(boolean exception) throws IOException {
-		socket.close();
+		try {
+			socket.close();
+		} finally {
+			connectionManager.connectionClosed(this);
+		}
 	}
 }

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

@@ -614,7 +614,7 @@ class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 
 	@Override
 	public DuplexTransportConnection createKeyAgreementConnection(
-			byte[] commitment, BdfList descriptor, long timeout) {
+			byte[] commitment, BdfList descriptor) {
 		throw new UnsupportedOperationException();
 	}
 

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

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

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

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

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

@@ -0,0 +1,39 @@
+package org.briarproject.bramble.keyagreement;
+
+import org.briarproject.bramble.api.keyagreement.KeyAgreementConnection;
+
+import javax.annotation.Nullable;
+
+interface ConnectionChooser {
+
+	/**
+	 * Adds a connection to the set of connections that may be chosen. If
+	 * {@link #stop()} has already been called, the connection will be closed
+	 * immediately.
+	 */
+	void addConnection(KeyAgreementConnection c);
+
+	/**
+	 * Chooses one of the connections passed to
+	 * {@link #addConnection(KeyAgreementConnection)} and returns it,
+	 * waiting up to the given amount of time for a suitable connection to
+	 * become available. Returns null if the time elapses without a suitable
+	 * connection becoming available.
+	 *
+	 * @param alice true if the local party is Alice
+	 * @param timeout the timeout in milliseconds
+	 * @throws InterruptedException if the thread is interrupted while waiting
+	 * for a suitable connection to become available
+	 */
+	@Nullable
+	KeyAgreementConnection chooseConnection(boolean alice, long timeout)
+			throws InterruptedException;
+
+	/**
+	 * Stops the chooser from accepting new connections. Closes any connections
+	 * already passed to {@link #addConnection(KeyAgreementConnection)}
+	 * and not chosen. Any connections subsequently passed to
+	 * {@link #addConnection(KeyAgreementConnection)} will be closed.
+	 */
+	void stop();
+}

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

@@ -0,0 +1,153 @@
+package org.briarproject.bramble.keyagreement;
+
+import org.briarproject.bramble.api.event.EventBus;
+import org.briarproject.bramble.api.keyagreement.KeyAgreementConnection;
+import org.briarproject.bramble.api.keyagreement.event.KeyAgreementWaitingEvent;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
+import org.briarproject.bramble.api.system.Clock;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Iterator;
+import java.util.List;
+import java.util.logging.Logger;
+
+import javax.annotation.Nullable;
+import javax.annotation.concurrent.ThreadSafe;
+import javax.inject.Inject;
+
+import static java.util.logging.Level.INFO;
+import static java.util.logging.Level.WARNING;
+
+@NotNullByDefault
+@ThreadSafe
+class ConnectionChooserImpl implements ConnectionChooser {
+
+	private static final Logger LOG =
+			Logger.getLogger(ConnectionChooserImpl.class.getName());
+
+	private final EventBus eventBus;
+	private final Clock clock;
+	private final Object lock = new Object();
+	private final List<KeyAgreementConnection> connections =
+			new ArrayList<>(); // Locking: lock
+	private boolean stopped = false; // Locking: lock
+
+	@Inject
+	ConnectionChooserImpl(EventBus eventBus, Clock clock) {
+		this.eventBus = eventBus;
+		this.clock = clock;
+	}
+
+	@Override
+	public void addConnection(KeyAgreementConnection conn) {
+		boolean close = false;
+		synchronized (lock) {
+			if (stopped) {
+				// Already stopped, close the connection
+				close = true;
+			} else {
+				connections.add(conn);
+				lock.notifyAll();
+			}
+		}
+		if (close) tryToClose(conn.getConnection());
+	}
+
+	@Nullable
+	@Override
+	public KeyAgreementConnection chooseConnection(boolean alice, long timeout)
+			throws InterruptedException {
+		if (alice) return chooseConnectionAlice(timeout);
+		else return chooseConnectionBob(timeout);
+	}
+
+	@Nullable
+	private KeyAgreementConnection chooseConnectionAlice(long timeout)
+			throws InterruptedException {
+		LOG.info("Choosing connection for Alice");
+		long now = clock.currentTimeMillis();
+		long end = now + timeout;
+		KeyAgreementConnection chosen;
+		synchronized (lock) {
+			// Wait until we're stopped, a connection is added, or we time out
+			while (!stopped && connections.isEmpty() && now < end) {
+				lock.wait(end - now);
+				now = clock.currentTimeMillis();
+			}
+			if (connections.isEmpty()) {
+				LOG.info("No suitable connection for Alice");
+				return null;
+			}
+			// Choose the first connection
+			chosen = connections.remove(0);
+		}
+		if (LOG.isLoggable(INFO))
+			LOG.info("Choosing " + chosen.getTransportId());
+		return chosen;
+	}
+
+	@Nullable
+	private KeyAgreementConnection chooseConnectionBob(long timeout)
+			throws InterruptedException {
+		LOG.info("Choosing connection for Bob");
+		// Bob waits here for Alice to scan his QR code, determine her role,
+		// choose a connection and send her key
+		eventBus.broadcast(new KeyAgreementWaitingEvent());
+		long now = clock.currentTimeMillis();
+		long end = now + timeout;
+		synchronized (lock) {
+			while (!stopped && now < end) {
+				// Check whether any connection has data available
+				Iterator<KeyAgreementConnection> it = connections.iterator();
+				while (it.hasNext()) {
+					KeyAgreementConnection c = it.next();
+					try {
+						int available = c.getConnection().getReader()
+								.getInputStream().available();
+						if (available > 0) {
+							if (LOG.isLoggable(INFO))
+								LOG.info("Choosing " + c.getTransportId());
+							it.remove();
+							return c;
+						}
+					} catch (IOException e) {
+						if (LOG.isLoggable(WARNING))
+							LOG.log(WARNING, e.toString(), e);
+						tryToClose(c.getConnection());
+						it.remove();
+					}
+				}
+				// Wait for 1 second before checking again
+				lock.wait(Math.min(1000, end - now));
+				now = clock.currentTimeMillis();
+			}
+		}
+		LOG.info("No suitable connection for Bob");
+		return null;
+	}
+
+	@Override
+	public void stop() {
+		List<KeyAgreementConnection> unused;
+		synchronized (lock) {
+			stopped = true;
+			unused = new ArrayList<>(connections);
+			connections.clear();
+			lock.notifyAll();
+		}
+		if (LOG.isLoggable(INFO))
+			LOG.info("Closing " + unused.size() + " unused connections");
+		for (KeyAgreementConnection c : unused) tryToClose(c.getConnection());
+	}
+
+	private void tryToClose(DuplexTransportConnection conn) {
+		try {
+			conn.getReader().dispose(false, true);
+			conn.getWriter().dispose(false);
+		} catch (IOException e) {
+			if (LOG.isLoggable(INFO)) LOG.info(e.toString());
+		}
+	}
+}

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

@@ -7,6 +7,7 @@ import org.briarproject.bramble.api.keyagreement.KeyAgreementConnection;
 import org.briarproject.bramble.api.keyagreement.KeyAgreementListener;
 import org.briarproject.bramble.api.keyagreement.Payload;
 import org.briarproject.bramble.api.keyagreement.TransportDescriptor;
+import org.briarproject.bramble.api.lifecycle.IoExecutor;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.Plugin;
 import org.briarproject.bramble.api.plugin.PluginManager;
@@ -16,20 +17,14 @@ import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
 import org.briarproject.bramble.api.system.Clock;
 
 import java.io.IOException;
-import java.io.InputStream;
 import java.util.ArrayList;
 import java.util.List;
-import java.util.concurrent.Callable;
-import java.util.concurrent.CompletionService;
-import java.util.concurrent.ExecutionException;
+import java.util.concurrent.CopyOnWriteArrayList;
 import java.util.concurrent.Executor;
-import java.util.concurrent.ExecutorCompletionService;
-import java.util.concurrent.Future;
 import java.util.logging.Logger;
 
 import javax.annotation.Nullable;
 
-import static java.util.concurrent.TimeUnit.MILLISECONDS;
 import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
 import static org.briarproject.bramble.api.keyagreement.KeyAgreementConstants.CONNECTION_TIMEOUT;
@@ -37,37 +32,31 @@ import static org.briarproject.bramble.api.keyagreement.KeyAgreementConstants.CO
 @NotNullByDefault
 class KeyAgreementConnector {
 
-	interface Callbacks {
-		void connectionWaiting();
-	}
-
 	private static final Logger LOG =
 			Logger.getLogger(KeyAgreementConnector.class.getName());
 
-	private final Callbacks callbacks;
 	private final Clock clock;
 	private final KeyAgreementCrypto keyAgreementCrypto;
 	private final PluginManager pluginManager;
-	private final CompletionService<KeyAgreementConnection> connect;
+	private final Executor ioExecutor;
+	private final ConnectionChooser connectionChooser;
 
-	private final List<KeyAgreementListener> listeners = new ArrayList<>();
-	private final List<Future<KeyAgreementConnection>> pending =
-			new ArrayList<>();
+	private final List<KeyAgreementListener> listeners =
+			new CopyOnWriteArrayList<>();
 
-	private volatile boolean connecting = false;
-	private volatile boolean alice = false;
+	private volatile boolean stopped = false;
 
-	KeyAgreementConnector(Callbacks callbacks, Clock clock,
-			KeyAgreementCrypto keyAgreementCrypto, PluginManager pluginManager,
-			Executor ioExecutor) {
-		this.callbacks = callbacks;
+	KeyAgreementConnector(Clock clock, KeyAgreementCrypto keyAgreementCrypto,
+			PluginManager pluginManager, Executor ioExecutor,
+			ConnectionChooser connectionChooser) {
 		this.clock = clock;
 		this.keyAgreementCrypto = keyAgreementCrypto;
 		this.pluginManager = pluginManager;
-		connect = new ExecutorCompletionService<>(ioExecutor);
+		this.ioExecutor = ioExecutor;
+		this.connectionChooser = connectionChooser;
 	}
 
-	public Payload listen(KeyPair localKeyPair) {
+	Payload listen(KeyPair localKeyPair) {
 		LOG.info("Starting BQP listeners");
 		// Derive commitment
 		byte[] commitment = keyAgreementCrypto.deriveKeyCommitment(
@@ -80,8 +69,16 @@ class KeyAgreementConnector {
 			if (l != null) {
 				TransportId id = plugin.getId();
 				descriptors.add(new TransportDescriptor(id, l.getDescriptor()));
-				pending.add(connect.submit(new ReadableTask(l.listen())));
+				if (LOG.isLoggable(INFO)) LOG.info("Listening via " + id);
 				listeners.add(l);
+				ioExecutor.execute(() -> {
+					try {
+						connectionChooser.addConnection(l.accept());
+					} catch (IOException e) {
+						if (LOG.isLoggable(WARNING))
+							LOG.log(WARNING, e.toString(), e);
+					}
+				});
 			}
 		}
 		return new Payload(commitment, descriptors);
@@ -89,152 +86,71 @@ class KeyAgreementConnector {
 
 	void stopListening() {
 		LOG.info("Stopping BQP listeners");
-		for (KeyAgreementListener l : listeners) {
-			l.close();
-		}
+		stopped = true;
+		for (KeyAgreementListener l : listeners) l.close();
 		listeners.clear();
+		connectionChooser.stop();
 	}
 
 	@Nullable
-	public KeyAgreementTransport connect(Payload remotePayload,
-			boolean alice) {
-		// Let the listeners know if we are Alice
-		this.connecting = true;
-		this.alice = alice;
-		long end = clock.currentTimeMillis() + CONNECTION_TIMEOUT;
-
+	public KeyAgreementTransport connect(Payload remotePayload, boolean alice) {
 		// Start connecting over supported transports
-		LOG.info("Starting outgoing BQP connections");
+		if (LOG.isLoggable(INFO)) {
+			LOG.info("Starting outgoing BQP connections as "
+					+ (alice ? "Alice" : "Bob"));
+		}
 		for (TransportDescriptor d : remotePayload.getTransportDescriptors()) {
 			Plugin p = pluginManager.getPlugin(d.getId());
 			if (p instanceof DuplexPlugin) {
+				if (LOG.isLoggable(INFO))
+					LOG.info("Connecting via " + d.getId());
 				DuplexPlugin plugin = (DuplexPlugin) p;
-				pending.add(connect.submit(new ReadableTask(
-						new ConnectorTask(plugin, remotePayload.getCommitment(),
-								d.getDescriptor(), end))));
+				byte[] commitment = remotePayload.getCommitment();
+				BdfList descriptor = d.getDescriptor();
+				ioExecutor.execute(() -> {
+					try {
+						KeyAgreementConnection c =
+								connect(plugin, commitment, descriptor);
+						if (c != null) connectionChooser.addConnection(c);
+					} catch (InterruptedException e) {
+						LOG.info("Interrupted while waiting to connect");
+					}
+				});
 			}
 		}
 
 		// Get chosen connection
-		KeyAgreementConnection chosen = null;
 		try {
-			long now = clock.currentTimeMillis();
-			Future<KeyAgreementConnection> f =
-					connect.poll(end - now, MILLISECONDS);
-			if (f == null)
-				return null; // No task completed within the timeout.
-			chosen = f.get();
+			KeyAgreementConnection chosen = connectionChooser.chooseConnection(
+					alice, CONNECTION_TIMEOUT);
+			if (chosen == null) return null; // No suitable connection
 			return new KeyAgreementTransport(chosen);
 		} catch (InterruptedException e) {
 			LOG.info("Interrupted while waiting for connection");
 			Thread.currentThread().interrupt();
 			return null;
-		} catch (ExecutionException | IOException e) {
+		} catch (IOException e) {
 			if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
 			return null;
 		} finally {
 			stopListening();
-			// Close all other connections
-			closePending(chosen);
 		}
 	}
 
-	private void closePending(@Nullable KeyAgreementConnection chosen) {
-		for (Future<KeyAgreementConnection> f : pending) {
-			try {
-				if (f.cancel(true)) {
-					LOG.info("Cancelled task");
-				} else if (!f.isCancelled()) {
-					KeyAgreementConnection c = f.get();
-					if (c != null && c != chosen)
-						tryToClose(c.getConnection(), false);
-				}
-			} catch (InterruptedException e) {
-				LOG.info("Interrupted while closing sockets");
-				Thread.currentThread().interrupt();
-				return;
-			} catch (ExecutionException e) {
-				if (LOG.isLoggable(INFO)) LOG.info(e.toString());
-			}
-		}
-	}
-
-	private void tryToClose(DuplexTransportConnection conn, boolean exception) {
-		try {
-			if (LOG.isLoggable(INFO))
-				LOG.info("Closing connection, exception: " + exception);
-			conn.getReader().dispose(exception, true);
-			conn.getWriter().dispose(exception);
-		} catch (IOException e) {
-			if (LOG.isLoggable(INFO)) LOG.info(e.toString());
-		}
-	}
-
-	private class ConnectorTask implements Callable<KeyAgreementConnection> {
-
-		private final byte[] commitment;
-		private final BdfList descriptor;
-		private final long end;
-		private final DuplexPlugin plugin;
-
-		private ConnectorTask(DuplexPlugin plugin, byte[] commitment,
-				BdfList descriptor, long end) {
-			this.plugin = plugin;
-			this.commitment = commitment;
-			this.descriptor = descriptor;
-			this.end = end;
-		}
-
-		@Override
-		public KeyAgreementConnection call() throws Exception {
-			// Repeat attempts until we connect, get interrupted, or time out
-			while (true) {
-				long now = clock.currentTimeMillis();
-				if (now > end) throw new IOException();
-				DuplexTransportConnection conn =
-						plugin.createKeyAgreementConnection(commitment,
-								descriptor, end - now);
-				if (conn != null) {
-					if (LOG.isLoggable(INFO))
-						LOG.info(plugin.getId().getString() +
-								": Outgoing connection");
-					return new KeyAgreementConnection(conn, plugin.getId());
-				}
-				// Wait 2s before retry (to circumvent transient failures)
-				Thread.sleep(2000);
-			}
-		}
-	}
-
-	private class ReadableTask
-			implements Callable<KeyAgreementConnection> {
-
-		private final Callable<KeyAgreementConnection> connectionTask;
-
-		private ReadableTask(Callable<KeyAgreementConnection> connectionTask) {
-			this.connectionTask = connectionTask;
-		}
-
-		@Override
-		public KeyAgreementConnection call() throws Exception {
-			KeyAgreementConnection c = connectionTask.call();
-			InputStream in = c.getConnection().getReader().getInputStream();
-			boolean waitingSent = false;
-			while (!alice && in.available() == 0) {
-				if (!waitingSent && connecting && !alice) {
-					// Bob waits here until Alice obtains his payload.
-					callbacks.connectionWaiting();
-					waitingSent = true;
-				}
-				if (LOG.isLoggable(INFO)) {
-					LOG.info(c.getTransportId().getString() +
-							": Waiting for connection");
-				}
-				Thread.sleep(1000);
-			}
-			if (!alice && LOG.isLoggable(INFO))
-				LOG.info(c.getTransportId().getString() + ": Data available");
-			return c;
+	@Nullable
+	@IoExecutor
+	private KeyAgreementConnection connect(DuplexPlugin plugin,
+			byte[] commitment, BdfList descriptor) throws InterruptedException {
+		// Repeat attempts until we time out, get stopped, or get interrupted
+		long end = clock.currentTimeMillis() + CONNECTION_TIMEOUT;
+		while (!stopped && clock.currentTimeMillis() < end) {
+			DuplexTransportConnection conn =
+					plugin.createKeyAgreementConnection(commitment, descriptor);
+			if (conn != null)
+				return new KeyAgreementConnection(conn, plugin.getId());
+			// Wait 2s before retry (to circumvent transient failures)
+			Thread.sleep(2000);
 		}
+		return null;
 	}
 }

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

@@ -27,4 +27,10 @@ public class KeyAgreementModule {
 	PayloadParser providePayloadParser(BdfReaderFactory bdfReaderFactory) {
 		return new PayloadParserImpl(bdfReaderFactory);
 	}
+
+	@Provides
+	ConnectionChooser provideConnectionChooser(
+			ConnectionChooserImpl connectionChooser) {
+		return connectionChooser;
+	}
 }

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

@@ -99,7 +99,8 @@ class KeyAgreementProtocol {
 			PublicKey theirPublicKey;
 			if (alice) {
 				sendKey();
-				// Alice waits here until Bob obtains her payload.
+				// Alice waits here for Bob to scan her QR code, determine his
+				// role, receive her key and respond with his key
 				callbacks.connectionWaiting();
 				theirPublicKey = receiveKey();
 			} else {

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

@@ -32,8 +32,7 @@ import static java.util.logging.Level.WARNING;
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
 class KeyAgreementTaskImpl extends Thread implements
-		KeyAgreementTask, KeyAgreementConnector.Callbacks,
-		KeyAgreementProtocol.Callbacks {
+		KeyAgreementTask, KeyAgreementProtocol.Callbacks {
 
 	private static final Logger LOG =
 			Logger.getLogger(KeyAgreementTaskImpl.class.getName());
@@ -52,14 +51,15 @@ class KeyAgreementTaskImpl extends Thread implements
 	KeyAgreementTaskImpl(Clock clock, CryptoComponent crypto,
 			KeyAgreementCrypto keyAgreementCrypto, EventBus eventBus,
 			PayloadEncoder payloadEncoder, PluginManager pluginManager,
-			@IoExecutor Executor ioExecutor) {
+			@IoExecutor Executor ioExecutor,
+			ConnectionChooser connectionChooser) {
 		this.crypto = crypto;
 		this.keyAgreementCrypto = keyAgreementCrypto;
 		this.eventBus = eventBus;
 		this.payloadEncoder = payloadEncoder;
 		localKeyPair = crypto.generateAgreementKeyPair();
-		connector = new KeyAgreementConnector(this, clock, keyAgreementCrypto,
-				pluginManager, ioExecutor);
+		connector = new KeyAgreementConnector(clock, keyAgreementCrypto,
+				pluginManager, ioExecutor, connectionChooser);
 	}
 
 	@Override
@@ -73,10 +73,8 @@ class KeyAgreementTaskImpl extends Thread implements
 	@Override
 	public synchronized void stopListening() {
 		if (localPayload != null) {
-			if (remotePayload == null)
-				connector.stopListening();
-			else
-				interrupt();
+			if (remotePayload == null) connector.stopListening();
+			else interrupt();
 		}
 	}
 

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

@@ -247,12 +247,12 @@ class ConnectionManagerImpl implements ConnectionManager {
 				ctx = keyManager.getStreamContext(transportId, tag);
 			} catch (IOException | DbException e) {
 				if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
-				disposeReader(true, false);
+				dispose(true, false);
 				return;
 			}
 			if (ctx == null) {
 				LOG.info("Unrecognised tag");
-				disposeReader(false, false);
+				dispose(false, false);
 				return;
 			}
 			contactId = ctx.getContactId();
@@ -263,10 +263,10 @@ class ConnectionManagerImpl implements ConnectionManager {
 				// Create and run the incoming session
 				incomingSession = createIncomingSession(ctx, reader);
 				incomingSession.run();
-				disposeReader(false, true);
+				dispose(false, true);
 			} catch (IOException e) {
 				if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
-				disposeReader(true, true);
+				dispose(true, true);
 			} finally {
 				connectionRegistry.unregisterConnection(contactId, transportId,
 						true);
@@ -280,39 +280,28 @@ class ConnectionManagerImpl implements ConnectionManager {
 				ctx = keyManager.getStreamContext(contactId, transportId);
 			} catch (DbException e) {
 				if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
-				disposeWriter(true);
+				dispose(true, true);
 				return;
 			}
 			if (ctx == null) {
 				LOG.warning("Could not allocate stream context");
-				disposeWriter(true);
+				dispose(true, true);
 				return;
 			}
 			try {
 				// Create and run the outgoing session
 				outgoingSession = createDuplexOutgoingSession(ctx, writer);
 				outgoingSession.run();
-				disposeWriter(false);
+				dispose(false, true);
 			} catch (IOException e) {
 				if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
-				disposeWriter(true);
+				dispose(true, true);
 			}
 		}
 
-		private void disposeReader(boolean exception, boolean recognised) {
-			if (exception && outgoingSession != null)
-				outgoingSession.interrupt();
+		private void dispose(boolean exception, boolean recognised) {
 			try {
 				reader.dispose(exception, recognised);
-			} catch (IOException e) {
-				if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
-			}
-		}
-
-		private void disposeWriter(boolean exception) {
-			if (exception && incomingSession != null)
-				incomingSession.interrupt();
-			try {
 				writer.dispose(exception);
 			} catch (IOException e) {
 				if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
@@ -346,12 +335,12 @@ class ConnectionManagerImpl implements ConnectionManager {
 				ctx = keyManager.getStreamContext(contactId, transportId);
 			} catch (DbException e) {
 				if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
-				disposeWriter(true);
+				dispose(true);
 				return;
 			}
 			if (ctx == null) {
 				LOG.warning("Could not allocate stream context");
-				disposeWriter(true);
+				dispose(true);
 				return;
 			}
 			// Start the incoming session on another thread
@@ -360,10 +349,10 @@ class ConnectionManagerImpl implements ConnectionManager {
 				// Create and run the outgoing session
 				outgoingSession = createDuplexOutgoingSession(ctx, writer);
 				outgoingSession.run();
-				disposeWriter(false);
+				dispose(false);
 			} catch (IOException e) {
 				if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
-				disposeWriter(true);
+				dispose(true);
 			}
 		}
 
@@ -375,19 +364,19 @@ class ConnectionManagerImpl implements ConnectionManager {
 				ctx = keyManager.getStreamContext(transportId, tag);
 			} catch (IOException | DbException e) {
 				if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
-				disposeReader(true, false);
+				dispose(true);
 				return;
 			}
 			// Unrecognised tags are suspicious in this case
 			if (ctx == null) {
 				LOG.warning("Unrecognised tag for returning stream");
-				disposeReader(true, false);
+				dispose(true);
 				return;
 			}
 			// Check that the stream comes from the expected contact
 			if (!ctx.getContactId().equals(contactId)) {
 				LOG.warning("Wrong contact ID for returning stream");
-				disposeReader(true, true);
+				dispose(true);
 				return;
 			}
 			connectionRegistry.registerConnection(contactId, transportId,
@@ -396,30 +385,20 @@ class ConnectionManagerImpl implements ConnectionManager {
 				// Create and run the incoming session
 				incomingSession = createIncomingSession(ctx, reader);
 				incomingSession.run();
-				disposeReader(false, true);
+				dispose(false);
 			} catch (IOException e) {
 				if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
-				disposeReader(true, true);
+				dispose(true);
 			} finally {
 				connectionRegistry.unregisterConnection(contactId, transportId,
 						false);
 			}
 		}
 
-		private void disposeReader(boolean exception, boolean recognised) {
-			if (exception && outgoingSession != null)
-				outgoingSession.interrupt();
-			try {
-				reader.dispose(exception, recognised);
-			} catch (IOException e) {
-				if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
-			}
-		}
-
-		private void disposeWriter(boolean exception) {
-			if (exception && incomingSession != null)
-				incomingSession.interrupt();
+		private void dispose(boolean exception) {
 			try {
+				// 'Recognised' is always true because we opened the connection
+				reader.dispose(exception, true);
 				writer.dispose(exception);
 			} catch (IOException e) {
 				if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);

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

@@ -0,0 +1,36 @@
+package org.briarproject.bramble.plugin.bluetooth;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
+
+@NotNullByDefault
+interface BluetoothConnectionManager {
+
+	/**
+	 * Returns true if a contact connection can be opened without exceeding
+	 * the connection limit. This method does not need to be called for key
+	 * exchange connections.
+	 */
+	boolean canOpenConnection();
+
+	/**
+	 * Passes a newly opened connection to the manager. The manager may close
+	 * the new connection or another connection to stay within the connection
+	 * limit.
+	 * <p/>
+	 * Returns false if the manager has closed the new connection (this will
+	 * never be the case for key exchange connections).
+	 */
+	boolean connectionOpened(DuplexTransportConnection conn,
+			boolean isForKeyExchange);
+
+	/**
+	 * Informs the manager that the given connection has been closed.
+	 */
+	void connectionClosed(DuplexTransportConnection conn);
+
+	/**
+	 * Informs the manager that all connections have been closed.
+	 */
+	void allConnectionsClosed();
+}

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

@@ -0,0 +1,88 @@
+package org.briarproject.bramble.plugin.bluetooth;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
+
+import java.io.IOException;
+import java.util.LinkedList;
+import java.util.logging.Logger;
+
+import javax.annotation.concurrent.ThreadSafe;
+
+import static java.util.logging.Level.INFO;
+
+@NotNullByDefault
+@ThreadSafe
+class BluetoothConnectionManagerImpl implements BluetoothConnectionManager {
+
+	private static final int MAX_OPEN_CONNECTIONS = 5;
+
+	private static final Logger LOG =
+			Logger.getLogger(BluetoothConnectionManagerImpl.class.getName());
+
+	private final Object lock = new Object();
+	private final LinkedList<DuplexTransportConnection> connections =
+			new LinkedList<>(); // Locking: lock
+
+	@Override
+	public boolean canOpenConnection() {
+		synchronized (lock) {
+			int open = connections.size();
+			if (LOG.isLoggable(INFO)) LOG.info(open + " open connections");
+			return open < MAX_OPEN_CONNECTIONS;
+		}
+	}
+
+	@Override
+	public boolean connectionOpened(DuplexTransportConnection conn,
+			boolean isForKeyExchange) {
+		DuplexTransportConnection close = null;
+		synchronized (lock) {
+			int open = connections.size();
+			boolean accept = isForKeyExchange || open < MAX_OPEN_CONNECTIONS;
+			if (accept) {
+				if (LOG.isLoggable(INFO))
+					LOG.info("Accepting connection, " + (open + 1) + " open");
+				connections.add(conn);
+				if (open == MAX_OPEN_CONNECTIONS) {
+					LOG.info("Closing old connection to stay within limit");
+					close = connections.poll();
+				}
+			} else {
+				if (LOG.isLoggable(INFO))
+					LOG.info("Refusing connection, " + open + " open");
+				close = conn;
+			}
+		}
+		if (close != null) tryToClose(close);
+		return close != conn;
+	}
+
+	private void tryToClose(DuplexTransportConnection conn) {
+		try {
+			conn.getReader().dispose(false, true);
+			conn.getWriter().dispose(false);
+		} catch (IOException e) {
+			if (LOG.isLoggable(INFO)) LOG.log(INFO, e.toString(), e);
+		}
+	}
+
+	@Override
+	public void connectionClosed(DuplexTransportConnection conn) {
+		synchronized (lock) {
+			connections.remove(conn);
+			if (LOG.isLoggable(INFO)) {
+				int open = connections.size();
+				LOG.info("Connection closed, " + open + " open");
+			}
+		}
+	}
+
+	@Override
+	public void allConnectionsClosed() {
+		synchronized (lock) {
+			connections.clear();
+			LOG.info("All connections closed");
+		}
+	}
+}

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

@@ -28,7 +28,6 @@ import java.util.Collection;
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.UUID;
-import java.util.concurrent.Callable;
 import java.util.concurrent.Executor;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.logging.Logger;
@@ -52,6 +51,8 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 	private static final Logger LOG =
 			Logger.getLogger(BluetoothPlugin.class.getName());
 
+	protected final BluetoothConnectionManager connectionManager;
+
 	private final Executor ioExecutor;
 	private final SecureRandom secureRandom;
 	private final Backoff backoff;
@@ -92,8 +93,10 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 	abstract DuplexTransportConnection connectTo(String address, String uuid)
 			throws IOException;
 
-	BluetoothPlugin(Executor ioExecutor, SecureRandom secureRandom,
+	BluetoothPlugin(BluetoothConnectionManager connectionManager,
+			Executor ioExecutor, SecureRandom secureRandom,
 			Backoff backoff, DuplexPluginCallback callback, int maxLatency) {
+		this.connectionManager = connectionManager;
 		this.ioExecutor = ioExecutor;
 		this.secureRandom = secureRandom;
 		this.backoff = backoff;
@@ -111,6 +114,7 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 	void onAdapterDisabled() {
 		LOG.info("Bluetooth disabled");
 		tryToClose(socket);
+		connectionManager.allConnectionsClosed();
 		callback.transportDisabled();
 	}
 
@@ -214,7 +218,8 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 				return;
 			}
 			backoff.reset();
-			callback.incomingConnectionCreated(conn);
+			if (connectionManager.connectionOpened(conn, false))
+				callback.incomingConnectionCreated(conn);
 			if (!running) return;
 		}
 	}
@@ -258,10 +263,15 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 			if (StringUtils.isNullOrEmpty(uuid)) continue;
 			ioExecutor.execute(() -> {
 				if (!isRunning() || !shouldAllowContactConnections()) return;
+				if (!connectionManager.canOpenConnection()) {
+					LOG.info("Not connecting, too many open connections");
+					return;
+				}
 				DuplexTransportConnection conn = connect(address, uuid);
 				if (conn != null) {
 					backoff.reset();
-					callback.outgoingConnectionCreated(c, conn);
+					if (connectionManager.connectionOpened(conn, false))
+						callback.outgoingConnectionCreated(c, conn);
 				}
 			});
 		}
@@ -301,12 +311,19 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 	@Override
 	public DuplexTransportConnection createConnection(ContactId c) {
 		if (!isRunning() || !shouldAllowContactConnections()) return null;
+		if (!connectionManager.canOpenConnection()) {
+			LOG.info("Not connecting, too many open connections");
+			return null;
+		}
 		TransportProperties p = callback.getRemoteProperties(c);
 		String address = p.get(PROP_ADDRESS);
 		if (StringUtils.isNullOrEmpty(address)) return null;
 		String uuid = p.get(PROP_UUID);
 		if (StringUtils.isNullOrEmpty(uuid)) return null;
-		return connect(address, uuid);
+		DuplexTransportConnection conn = connect(address, uuid);
+		if (conn == null) return null;
+		// TODO: Why don't we reset the backoff here?
+		return connectionManager.connectionOpened(conn, false) ? conn : null;
 	}
 
 	@Override
@@ -343,7 +360,7 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 
 	@Override
 	public DuplexTransportConnection createKeyAgreementConnection(
-			byte[] commitment, BdfList descriptor, long timeout) {
+			byte[] commitment, BdfList descriptor) {
 		if (!isRunning()) return null;
 		String address;
 		try {
@@ -356,7 +373,10 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 		String uuid = UUID.nameUUIDFromBytes(commitment).toString();
 		if (LOG.isLoggable(INFO))
 			LOG.info("Connecting to key agreement UUID " + uuid);
-		return connect(address, uuid);
+		DuplexTransportConnection conn = connect(address, uuid);
+		// The connection limit doesn't apply to key agreement
+		if (conn != null) connectionManager.connectionOpened(conn, true);
+		return conn;
 	}
 
 	private String parseAddress(BdfList descriptor) throws FormatException {
@@ -406,13 +426,12 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 		}
 
 		@Override
-		public Callable<KeyAgreementConnection> listen() {
-			return () -> {
-				DuplexTransportConnection conn = acceptConnection(ss);
-				if (LOG.isLoggable(INFO))
-					LOG.info(ID.getString() + ": Incoming connection");
-				return new KeyAgreementConnection(conn, ID);
-			};
+		public KeyAgreementConnection accept() throws IOException {
+			DuplexTransportConnection conn = acceptConnection(ss);
+			if (LOG.isLoggable(INFO)) LOG.info(ID + ": Incoming connection");
+			// The connection limit doesn't apply to key agreement
+			connectionManager.connectionOpened(conn, true);
+			return new KeyAgreementConnection(conn, ID);
 		}
 
 		@Override

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

@@ -25,7 +25,6 @@ import java.util.ArrayList;
 import java.util.Collections;
 import java.util.Comparator;
 import java.util.List;
-import java.util.concurrent.Callable;
 import java.util.concurrent.Executor;
 import java.util.logging.Logger;
 
@@ -224,7 +223,7 @@ class LanTcpPlugin extends TcpPlugin {
 
 	@Override
 	public DuplexTransportConnection createKeyAgreementConnection(
-			byte[] commitment, BdfList descriptor, long timeout) {
+			byte[] commitment, BdfList descriptor) {
 		if (!isRunning()) return null;
 		InetSocketAddress remote;
 		try {
@@ -283,14 +282,11 @@ class LanTcpPlugin extends TcpPlugin {
 		}
 
 		@Override
-		public Callable<KeyAgreementConnection> listen() {
-			return () -> {
-				Socket s = ss.accept();
-				if (LOG.isLoggable(INFO))
-					LOG.info(ID.getString() + ": Incoming connection");
-				return new KeyAgreementConnection(
-						new TcpTransportConnection(LanTcpPlugin.this, s), ID);
-			};
+		public KeyAgreementConnection accept() throws IOException {
+			Socket s = ss.accept();
+			if (LOG.isLoggable(INFO)) LOG.info(ID + ": Incoming connection");
+			return new KeyAgreementConnection(new TcpTransportConnection(
+					LanTcpPlugin.this, s), ID);
 		}
 
 		@Override

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

@@ -297,7 +297,7 @@ abstract class TcpPlugin implements DuplexPlugin {
 
 	@Override
 	public DuplexTransportConnection createKeyAgreementConnection(
-			byte[] commitment, BdfList descriptor, long timeout) {
+			byte[] commitment, BdfList descriptor) {
 		throw new UnsupportedOperationException();
 	}
 

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

@@ -2,7 +2,6 @@ package org.briarproject.bramble.plugin.tcp;
 
 import org.briarproject.bramble.api.contact.ContactId;
 import org.briarproject.bramble.api.data.BdfList;
-import org.briarproject.bramble.api.keyagreement.KeyAgreementConnection;
 import org.briarproject.bramble.api.keyagreement.KeyAgreementListener;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.Backoff;
@@ -26,11 +25,9 @@ import java.util.Collections;
 import java.util.Comparator;
 import java.util.Hashtable;
 import java.util.Map;
-import java.util.concurrent.Callable;
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.Executor;
 import java.util.concurrent.Executors;
-import java.util.concurrent.FutureTask;
 import java.util.concurrent.atomic.AtomicBoolean;
 
 import static java.util.concurrent.TimeUnit.SECONDS;
@@ -195,9 +192,16 @@ public class LanTcpPluginTest extends BrambleTestCase {
 		KeyAgreementListener kal =
 				plugin.createKeyAgreementListener(new byte[COMMIT_LENGTH]);
 		assertNotNull(kal);
-		Callable<KeyAgreementConnection> c = kal.listen();
-		FutureTask<KeyAgreementConnection> f = new FutureTask<>(c);
-		new Thread(f).start();
+		CountDownLatch latch = new CountDownLatch(1);
+		AtomicBoolean error = new AtomicBoolean(false);
+		new Thread(() -> {
+			try {
+				kal.accept();
+				latch.countDown();
+			} catch (IOException e) {
+				error.set(true);
+			}
+		}).start();
 		// The plugin should have bound a socket and stored the port number
 		BdfList descriptor = kal.getDescriptor();
 		assertEquals(3, descriptor.size());
@@ -213,10 +217,12 @@ public class LanTcpPluginTest extends BrambleTestCase {
 		InetSocketAddress socketAddr = new InetSocketAddress(addr, port);
 		Socket s = new Socket();
 		s.connect(socketAddr, 100);
-		assertNotNull(f.get(5, SECONDS));
+		// Check that the connection was accepted
+		assertTrue(latch.await(5, SECONDS));
+		assertFalse(error.get());
+		// Clean up
 		s.close();
 		kal.close();
-		// Stop the plugin
 		plugin.stop();
 	}
 
@@ -262,7 +268,7 @@ public class LanTcpPluginTest extends BrambleTestCase {
 		descriptor.add(local.getPort());
 		// Connect to the port
 		DuplexTransportConnection d = plugin.createKeyAgreementConnection(
-				new byte[COMMIT_LENGTH], descriptor, 5000);
+				new byte[COMMIT_LENGTH], descriptor);
 		assertNotNull(d);
 		// Check that the connection was accepted
 		assertTrue(latch.await(5, SECONDS));

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

@@ -31,9 +31,11 @@ class JavaBluetoothPlugin extends BluetoothPlugin<StreamConnectionNotifier> {
 	// Non-null if the plugin started successfully
 	private volatile LocalDevice localDevice = null;
 
-	JavaBluetoothPlugin(Executor ioExecutor, SecureRandom secureRandom,
+	JavaBluetoothPlugin(BluetoothConnectionManager connectionManager,
+			Executor ioExecutor, SecureRandom secureRandom,
 			Backoff backoff, DuplexPluginCallback callback, int maxLatency) {
-		super(ioExecutor, secureRandom, backoff, callback, maxLatency);
+		super(connectionManager, ioExecutor, secureRandom, backoff, callback,
+				maxLatency);
 	}
 
 	@Override
@@ -110,6 +112,6 @@ class JavaBluetoothPlugin extends BluetoothPlugin<StreamConnectionNotifier> {
 	}
 
 	private DuplexTransportConnection wrapSocket(StreamConnection s) {
-		return new JavaBluetoothTransportConnection(this, s);
+		return new JavaBluetoothTransportConnection(this, connectionManager, s);
 	}
 }

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

@@ -51,10 +51,12 @@ public class JavaBluetoothPluginFactory implements DuplexPluginFactory {
 
 	@Override
 	public DuplexPlugin createPlugin(DuplexPluginCallback callback) {
+		BluetoothConnectionManager connectionManager =
+				new BluetoothConnectionManagerImpl();
 		Backoff backoff = backoffFactory.createBackoff(MIN_POLLING_INTERVAL,
 				MAX_POLLING_INTERVAL, BACKOFF_BASE);
-		JavaBluetoothPlugin plugin = new JavaBluetoothPlugin(ioExecutor,
-				secureRandom, backoff, callback, MAX_LATENCY);
+		JavaBluetoothPlugin plugin = new JavaBluetoothPlugin(connectionManager,
+				ioExecutor, secureRandom, backoff, callback, MAX_LATENCY);
 		eventBus.addListener(plugin);
 		return plugin;
 	}

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

@@ -14,11 +14,15 @@ import javax.microedition.io.StreamConnection;
 class JavaBluetoothTransportConnection
 		extends AbstractDuplexTransportConnection {
 
+	private final BluetoothConnectionManager connectionManager;
 	private final StreamConnection stream;
 
-	JavaBluetoothTransportConnection(Plugin plugin, StreamConnection stream) {
+	JavaBluetoothTransportConnection(Plugin plugin,
+			BluetoothConnectionManager connectionManager,
+			StreamConnection stream) {
 		super(plugin);
 		this.stream = stream;
+		this.connectionManager = connectionManager;
 	}
 
 	@Override
@@ -33,6 +37,10 @@ class JavaBluetoothTransportConnection
 
 	@Override
 	protected void closeConnection(boolean exception) throws IOException {
-		stream.close();
+		try {
+			stream.close();
+		} finally {
+			connectionManager.connectionClosed(this);
+		}
 	}
 }

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

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