Added a connection registry to avoid creating redundant connections.

components/net/sf/briar/plugins/PluginManagerImpl.java

@@ -51,8 +51,8 @@ class PluginManagerImpl implements PluginManager {
 		"net.sf.briar.plugins.socket.SimpleSocketPluginFactory"
 	};
 
-	private final DatabaseComponent db;
 	private final Executor pluginExecutor;
+	private final DatabaseComponent db;
 	private final Poller poller;
 	private final ConnectionDispatcher dispatcher;
 	private final UiCallback uiCallback;
@@ -60,11 +60,11 @@ class PluginManagerImpl implements PluginManager {
 	private final List<StreamPlugin> streamPlugins; // Locking: this
 
 	@Inject
-	PluginManagerImpl(DatabaseComponent db,
-			@PluginExecutor Executor pluginExecutor, Poller poller,
+	PluginManagerImpl(@PluginExecutor Executor pluginExecutor,
+			DatabaseComponent db, Poller poller,
 			ConnectionDispatcher dispatcher, UiCallback uiCallback) {
-		this.db = db;
 		this.pluginExecutor = pluginExecutor;
+		this.db = db;
 		this.poller = poller;
 		this.dispatcher = dispatcher;
 		this.uiCallback = uiCallback;
@@ -295,7 +295,7 @@ class PluginManagerImpl implements PluginManager {
 
 		public void writerCreated(ContactId c, BatchTransportWriter w) {
 			assert index != null;
-			dispatcher.dispatchWriter(c, index, w);
+			dispatcher.dispatchWriter(c, id, index, w);
 		}
 	}
 
@@ -310,7 +310,7 @@ class PluginManagerImpl implements PluginManager {
 		public void outgoingConnectionCreated(ContactId c,
 				StreamTransportConnection s) {
 			assert index != null;
-			dispatcher.dispatchOutgoingConnection(c, index, s);
+			dispatcher.dispatchOutgoingConnection(c, id, index, s);
 		}
 	}
 }

components/net/sf/briar/plugins/PollerImpl.java

@@ -6,14 +6,25 @@ import java.util.TreeSet;
 import java.util.logging.Level;
 import java.util.logging.Logger;
 
+import net.sf.briar.api.ContactId;
 import net.sf.briar.api.plugins.Plugin;
+import net.sf.briar.api.transport.ConnectionRegistry;
+
+import com.google.inject.Inject;
 
 class PollerImpl implements Poller, Runnable {
 
 	private static final Logger LOG =
 		Logger.getLogger(PollerImpl.class.getName());
 
-	private final SortedSet<PollTime> pollTimes = new TreeSet<PollTime>();
+	private final ConnectionRegistry connRegistry;
+	private final SortedSet<PollTime> pollTimes;
+
+	@Inject
+	PollerImpl(ConnectionRegistry connRegistry) {
+		this.connRegistry = connRegistry;
+		pollTimes = new TreeSet<PollTime>();
+	}
 
 	public synchronized void startPolling(Collection<Plugin> plugins) {
 		for(Plugin plugin : plugins) schedule(plugin);
@@ -41,8 +52,10 @@ class PollerImpl implements Poller, Runnable {
 				long now = System.currentTimeMillis();
 				if(now <= p.time) {
 					pollTimes.remove(p);
+					Collection<ContactId> connected =
+						connRegistry.getConnectedContacts(p.plugin.getId());
 					try {
-						p.plugin.poll();
+						p.plugin.poll(connected);
 					} catch(RuntimeException e) {
 						if(LOG.isLoggable(Level.WARNING))
 							LOG.warning("Plugin " + p.plugin.getId() + " " + e);

components/net/sf/briar/plugins/bluetooth/BluetoothPlugin.java

@@ -1,6 +1,7 @@
 package net.sf.briar.plugins.bluetooth;
 
 import java.io.IOException;
+import java.util.Collection;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.Map;
@@ -178,18 +179,18 @@ class BluetoothPlugin implements StreamPlugin {
 		return pollingInterval;
 	}
 
-	public void poll() {
+	public void poll(final Collection<ContactId> connected) {
 		synchronized(this) {
 			if(!running) return;
 		}
 		pluginExecutor.execute(new Runnable() {
 			public void run() {
-				connectAndCallBack();
+				connectAndCallBack(connected);
 			}
 		});
 	}
 
-	private void connectAndCallBack() {
+	private void connectAndCallBack(Collection<ContactId> connected) {
 		synchronized(this) {
 			if(!running) return;
 		}
@@ -198,6 +199,8 @@ class BluetoothPlugin implements StreamPlugin {
 		Map<ContactId, String> discovered = discoverContactUrls(remote);
 		for(Entry<ContactId, String> e : discovered.entrySet()) {
 			ContactId c = e.getKey();
+			// Don't create redundant connections
+			if(connected.contains(c)) continue;
 			String url = e.getValue();
 			StreamTransportConnection s = connect(c, url);
 			if(s != null) callback.outgoingConnectionCreated(c, s);

components/net/sf/briar/plugins/file/RemovableDrivePlugin.java

@@ -10,6 +10,7 @@ import java.util.concurrent.Executor;
 import java.util.logging.Level;
 import java.util.logging.Logger;
 
+import net.sf.briar.api.ContactId;
 import net.sf.briar.api.plugins.BatchPluginCallback;
 import net.sf.briar.api.plugins.PluginExecutor;
 import net.sf.briar.api.protocol.TransportId;
@@ -59,7 +60,7 @@ implements RemovableDriveMonitor.Callback {
 		throw new UnsupportedOperationException();
 	}
 
-	public void poll() {
+	public void poll(Collection<ContactId> connected) {
 		throw new UnsupportedOperationException();
 	}
 

components/net/sf/briar/plugins/socket/SimpleSocketPlugin.java

@@ -31,26 +31,15 @@ class SimpleSocketPlugin extends SocketPlugin {
 	private static final Logger LOG =
 		Logger.getLogger(SimpleSocketPlugin.class.getName());
 
-	private final long pollingInterval;
-
 	SimpleSocketPlugin(@PluginExecutor Executor pluginExecutor,
 			StreamPluginCallback callback, long pollingInterval) {
-		super(pluginExecutor, callback);
-		this.pollingInterval = pollingInterval;
+		super(pluginExecutor, callback, pollingInterval);
 	}
 
 	public TransportId getId() {
 		return id;
 	}
 
-	public boolean shouldPoll() {
-		return true;
-	}
-
-	public long getPollingInterval() {
-		return pollingInterval;
-	}
-
 	@Override
 	protected Socket createClientSocket() throws IOException {
 		assert running;

components/net/sf/briar/plugins/socket/SocketPlugin.java

@@ -4,6 +4,7 @@ import java.io.IOException;
 import java.net.ServerSocket;
 import java.net.Socket;
 import java.net.SocketAddress;
+import java.util.Collection;
 import java.util.Map;
 import java.util.concurrent.Executor;
 import java.util.logging.Level;
@@ -24,6 +25,8 @@ abstract class SocketPlugin implements StreamPlugin {
 	protected final Executor pluginExecutor;
 	protected final StreamPluginCallback callback;
 
+	private final long pollingInterval;
+
 	protected boolean running = false; // Locking: this
 	protected ServerSocket socket = null; // Locking: this
 
@@ -35,9 +38,10 @@ abstract class SocketPlugin implements StreamPlugin {
 	protected abstract SocketAddress getRemoteSocketAddress(ContactId c);
 
 	protected SocketPlugin(@PluginExecutor Executor pluginExecutor,
-			StreamPluginCallback callback) {
+			StreamPluginCallback callback, long pollingInterval) {
 		this.pluginExecutor = pluginExecutor;
 		this.callback = callback;
+		this.pollingInterval = pollingInterval;
 	}
 
 	public void start() throws IOException {
@@ -115,13 +119,22 @@ abstract class SocketPlugin implements StreamPlugin {
 		}
 	}
 
-	public void poll() {
+	public boolean shouldPoll() {
+		return true;
+	}
+
+	public long getPollingInterval() {
+		return pollingInterval;
+	}
+
+	public void poll(Collection<ContactId> connected) {
 		synchronized(this) {
 			if(!running) return;
 		}
 		Map<ContactId, TransportProperties> remote =
 			callback.getRemoteProperties();
 		for(final ContactId c : remote.keySet()) {
+			if(connected.contains(c)) continue;
 			pluginExecutor.execute(new Runnable() {
 				public void run() {
 					connectAndCallBack(c);

components/net/sf/briar/protocol/batch/BatchConnectionFactoryImpl.java

@@ -7,6 +7,7 @@ import net.sf.briar.api.db.DatabaseComponent;
 import net.sf.briar.api.db.DatabaseExecutor;
 import net.sf.briar.api.protocol.ProtocolReaderFactory;
 import net.sf.briar.api.protocol.ProtocolWriterFactory;
+import net.sf.briar.api.protocol.TransportId;
 import net.sf.briar.api.protocol.TransportIndex;
 import net.sf.briar.api.protocol.VerificationExecutor;
 import net.sf.briar.api.protocol.batch.BatchConnectionFactory;
@@ -14,6 +15,7 @@ import net.sf.briar.api.transport.BatchTransportReader;
 import net.sf.briar.api.transport.BatchTransportWriter;
 import net.sf.briar.api.transport.ConnectionContext;
 import net.sf.briar.api.transport.ConnectionReaderFactory;
+import net.sf.briar.api.transport.ConnectionRegistry;
 import net.sf.briar.api.transport.ConnectionWriterFactory;
 
 import com.google.inject.Inject;
@@ -22,6 +24,7 @@ class BatchConnectionFactoryImpl implements BatchConnectionFactory {
 
 	private final Executor dbExecutor, verificationExecutor;
 	private final DatabaseComponent db;
+	private final ConnectionRegistry connRegistry;
 	private final ConnectionReaderFactory connReaderFactory;
 	private final ConnectionWriterFactory connWriterFactory;
 	private final ProtocolReaderFactory protoReaderFactory;
@@ -30,24 +33,26 @@ class BatchConnectionFactoryImpl implements BatchConnectionFactory {
 	@Inject
 	BatchConnectionFactoryImpl(@DatabaseExecutor Executor dbExecutor,
 			@VerificationExecutor Executor verificationExecutor,
-			DatabaseComponent db, ConnectionReaderFactory connReaderFactory,
+			DatabaseComponent db, ConnectionRegistry connRegistry,
+			ConnectionReaderFactory connReaderFactory,
 			ConnectionWriterFactory connWriterFactory,
 			ProtocolReaderFactory protoReaderFactory,
 			ProtocolWriterFactory protoWriterFactory) {
 		this.dbExecutor = dbExecutor;
 		this.verificationExecutor = verificationExecutor;
 		this.db = db;
+		this.connRegistry = connRegistry;
 		this.connReaderFactory = connReaderFactory;
 		this.connWriterFactory = connWriterFactory;
 		this.protoReaderFactory = protoReaderFactory;
 		this.protoWriterFactory = protoWriterFactory;
 	}
 
-	public void createIncomingConnection(ConnectionContext ctx,
+	public void createIncomingConnection(ConnectionContext ctx, TransportId t,
 			BatchTransportReader r, byte[] tag) {
 		final IncomingBatchConnection conn = new IncomingBatchConnection(
-				dbExecutor, verificationExecutor, db, connReaderFactory,
-				protoReaderFactory, ctx, r, tag);
+				dbExecutor, verificationExecutor, db, connRegistry,
+				connReaderFactory, protoReaderFactory, ctx, t, r, tag);
 		Runnable read = new Runnable() {
 			public void run() {
 				conn.read();
@@ -56,10 +61,11 @@ class BatchConnectionFactoryImpl implements BatchConnectionFactory {
 		new Thread(read).start();
 	}
 
-	public void createOutgoingConnection(ContactId c, TransportIndex i,
-			BatchTransportWriter w) {
+	public void createOutgoingConnection(ContactId c, TransportId t,
+			TransportIndex i, BatchTransportWriter w) {
 		final OutgoingBatchConnection conn = new OutgoingBatchConnection(db,
-				connWriterFactory, protoWriterFactory, c, i, w);
+				connRegistry, connWriterFactory, protoWriterFactory,
+				c, t, i, w);
 		Runnable write = new Runnable() {
 			public void run() {
 				conn.write();

components/net/sf/briar/protocol/batch/IncomingBatchConnection.java

@@ -17,6 +17,7 @@ import net.sf.briar.api.protocol.Batch;
 import net.sf.briar.api.protocol.ProtocolReader;
 import net.sf.briar.api.protocol.ProtocolReaderFactory;
 import net.sf.briar.api.protocol.SubscriptionUpdate;
+import net.sf.briar.api.protocol.TransportId;
 import net.sf.briar.api.protocol.TransportUpdate;
 import net.sf.briar.api.protocol.UnverifiedBatch;
 import net.sf.briar.api.protocol.VerificationExecutor;
@@ -24,6 +25,7 @@ import net.sf.briar.api.transport.BatchTransportReader;
 import net.sf.briar.api.transport.ConnectionContext;
 import net.sf.briar.api.transport.ConnectionReader;
 import net.sf.briar.api.transport.ConnectionReaderFactory;
+import net.sf.briar.api.transport.ConnectionRegistry;
 
 class IncomingBatchConnection {
 
@@ -31,31 +33,38 @@ class IncomingBatchConnection {
 		Logger.getLogger(IncomingBatchConnection.class.getName());
 
 	private final Executor dbExecutor, verificationExecutor;
-	private final ConnectionReaderFactory connFactory;
 	private final DatabaseComponent db;
+	private final ConnectionRegistry connRegistry;
+	private final ConnectionReaderFactory connFactory;
 	private final ProtocolReaderFactory protoFactory;
 	private final ConnectionContext ctx;
+	private final TransportId transportId;
 	private final BatchTransportReader transport;
 	private final byte[] tag;
 	private final ContactId contactId;
 
 	IncomingBatchConnection(@DatabaseExecutor Executor dbExecutor,
 			@VerificationExecutor Executor verificationExecutor,
-			DatabaseComponent db, ConnectionReaderFactory connFactory,
+			DatabaseComponent db, ConnectionRegistry connRegistry,
+			ConnectionReaderFactory connFactory,
 			ProtocolReaderFactory protoFactory, ConnectionContext ctx,
-			BatchTransportReader transport, byte[] tag) {
+			TransportId transportId, BatchTransportReader transport,
+			byte[] tag) {
 		this.dbExecutor = dbExecutor;
 		this.verificationExecutor = verificationExecutor;
-		this.connFactory = connFactory;
 		this.db = db;
+		this.connRegistry = connRegistry;
+		this.connFactory = connFactory;
 		this.protoFactory = protoFactory;
 		this.ctx = ctx;
+		this.transportId = transportId;
 		this.transport = transport;
 		this.tag = tag;
 		contactId = ctx.getContactId();
 	}
 
 	void read() {
+		connRegistry.registerConnection(contactId, transportId);
 		try {
 			ConnectionReader conn = connFactory.createConnectionReader(
 					transport.getInputStream(), ctx.getSecret(), tag);
@@ -83,6 +92,8 @@ class IncomingBatchConnection {
 		} catch(IOException e) {
 			if(LOG.isLoggable(Level.WARNING)) LOG.warning(e.toString());
 			transport.dispose(true, true);
+		} finally {
+			connRegistry.unregisterConnection(contactId, transportId);
 		}
 	}
 

components/net/sf/briar/protocol/batch/OutgoingBatchConnection.java

@@ -16,10 +16,12 @@ import net.sf.briar.api.protocol.ProtocolWriter;
 import net.sf.briar.api.protocol.ProtocolWriterFactory;
 import net.sf.briar.api.protocol.RawBatch;
 import net.sf.briar.api.protocol.SubscriptionUpdate;
+import net.sf.briar.api.protocol.TransportId;
 import net.sf.briar.api.protocol.TransportIndex;
 import net.sf.briar.api.protocol.TransportUpdate;
 import net.sf.briar.api.transport.BatchTransportWriter;
 import net.sf.briar.api.transport.ConnectionContext;
+import net.sf.briar.api.transport.ConnectionRegistry;
 import net.sf.briar.api.transport.ConnectionWriter;
 import net.sf.briar.api.transport.ConnectionWriterFactory;
 
@@ -29,25 +31,32 @@ class OutgoingBatchConnection {
 		Logger.getLogger(OutgoingBatchConnection.class.getName());
 
 	private final DatabaseComponent db;
+	private final ConnectionRegistry connRegistry;
 	private final ConnectionWriterFactory connFactory;
 	private final ProtocolWriterFactory protoFactory;
 	private final ContactId contactId;
+	private final TransportId transportId;
 	private final TransportIndex transportIndex;
 	private final BatchTransportWriter transport;
 
 	OutgoingBatchConnection(DatabaseComponent db,
+			ConnectionRegistry connRegistry,
 			ConnectionWriterFactory connFactory,
 			ProtocolWriterFactory protoFactory, ContactId contactId,
-			TransportIndex transportIndex, BatchTransportWriter transport) {
+			TransportId transportId, TransportIndex transportIndex,
+			BatchTransportWriter transport) {
 		this.db = db;
+		this.connRegistry = connRegistry;
 		this.connFactory = connFactory;
 		this.protoFactory = protoFactory;
 		this.contactId = contactId;
+		this.transportId = transportId;
 		this.transportIndex = transportIndex;
 		this.transport = transport;
 	}
 
 	void write() {
+		connRegistry.registerConnection(contactId, transportId);
 		try {
 			ConnectionContext ctx = db.getConnectionContext(contactId,
 					transportIndex);
@@ -97,6 +106,8 @@ class OutgoingBatchConnection {
 		} catch(IOException e) {
 			if(LOG.isLoggable(Level.WARNING)) LOG.warning(e.toString());
 			transport.dispose(true);
+		} finally {
+			connRegistry.unregisterConnection(contactId, transportId);
 		}
 	}
 }

components/net/sf/briar/protocol/stream/IncomingStreamConnection.java

@@ -7,10 +7,12 @@ import net.sf.briar.api.db.DatabaseComponent;
 import net.sf.briar.api.db.DatabaseExecutor;
 import net.sf.briar.api.protocol.ProtocolReaderFactory;
 import net.sf.briar.api.protocol.ProtocolWriterFactory;
+import net.sf.briar.api.protocol.TransportId;
 import net.sf.briar.api.protocol.VerificationExecutor;
 import net.sf.briar.api.transport.ConnectionContext;
 import net.sf.briar.api.transport.ConnectionReader;
 import net.sf.briar.api.transport.ConnectionReaderFactory;
+import net.sf.briar.api.transport.ConnectionRegistry;
 import net.sf.briar.api.transport.ConnectionWriter;
 import net.sf.briar.api.transport.ConnectionWriterFactory;
 import net.sf.briar.api.transport.StreamTransportConnection;
@@ -22,15 +24,16 @@ class IncomingStreamConnection extends StreamConnection {
 
 	IncomingStreamConnection(@DatabaseExecutor Executor dbExecutor,
 			@VerificationExecutor Executor verificationExecutor,
-			DatabaseComponent db, ConnectionReaderFactory connReaderFactory,
+			DatabaseComponent db, ConnectionRegistry connRegistry,
+			ConnectionReaderFactory connReaderFactory,
 			ConnectionWriterFactory connWriterFactory,
 			ProtocolReaderFactory protoReaderFactory,
 			ProtocolWriterFactory protoWriterFactory,
-			ConnectionContext ctx, StreamTransportConnection transport,
-			byte[] tag) {
-		super(dbExecutor, verificationExecutor, db, connReaderFactory,
-				connWriterFactory, protoReaderFactory, protoWriterFactory,
-				ctx.getContactId(), transport);
+			ConnectionContext ctx, TransportId transportId,
+			StreamTransportConnection transport, byte[] tag) {
+		super(dbExecutor, verificationExecutor, db, connRegistry,
+				connReaderFactory, connWriterFactory, protoReaderFactory,
+				protoWriterFactory, ctx.getContactId(), transportId, transport);
 		this.ctx = ctx;
 		this.tag = tag;
 	}

components/net/sf/briar/protocol/stream/OutgoingStreamConnection.java

@@ -9,11 +9,13 @@ import net.sf.briar.api.db.DatabaseExecutor;
 import net.sf.briar.api.db.DbException;
 import net.sf.briar.api.protocol.ProtocolReaderFactory;
 import net.sf.briar.api.protocol.ProtocolWriterFactory;
+import net.sf.briar.api.protocol.TransportId;
 import net.sf.briar.api.protocol.TransportIndex;
 import net.sf.briar.api.protocol.VerificationExecutor;
 import net.sf.briar.api.transport.ConnectionContext;
 import net.sf.briar.api.transport.ConnectionReader;
 import net.sf.briar.api.transport.ConnectionReaderFactory;
+import net.sf.briar.api.transport.ConnectionRegistry;
 import net.sf.briar.api.transport.ConnectionWriter;
 import net.sf.briar.api.transport.ConnectionWriterFactory;
 import net.sf.briar.api.transport.StreamTransportConnection;
@@ -26,15 +28,16 @@ class OutgoingStreamConnection extends StreamConnection {
 
 	OutgoingStreamConnection(@DatabaseExecutor Executor dbExecutor,
 			@VerificationExecutor Executor verificationExecutor,
-			DatabaseComponent db, ConnectionReaderFactory connReaderFactory,
+			DatabaseComponent db, ConnectionRegistry connRegistry,
+			ConnectionReaderFactory connReaderFactory,
 			ConnectionWriterFactory connWriterFactory,
 			ProtocolReaderFactory protoReaderFactory,
 			ProtocolWriterFactory protoWriterFactory, ContactId contactId,
-			TransportIndex transportIndex,
+			TransportId transportId, TransportIndex transportIndex,
 			StreamTransportConnection transport) {
-		super(dbExecutor, verificationExecutor, db, connReaderFactory,
-				connWriterFactory, protoReaderFactory, protoWriterFactory,
-				contactId, transport);
+		super(dbExecutor, verificationExecutor, db, connRegistry,
+				connReaderFactory, connWriterFactory, protoReaderFactory,
+				protoWriterFactory, contactId, transportId, transport);
 		this.transportIndex = transportIndex;
 	}
 

components/net/sf/briar/protocol/stream/StreamConnection.java

@@ -40,11 +40,13 @@ import net.sf.briar.api.protocol.ProtocolWriterFactory;
 import net.sf.briar.api.protocol.RawBatch;
 import net.sf.briar.api.protocol.Request;
 import net.sf.briar.api.protocol.SubscriptionUpdate;
+import net.sf.briar.api.protocol.TransportId;
 import net.sf.briar.api.protocol.TransportUpdate;
 import net.sf.briar.api.protocol.UnverifiedBatch;
 import net.sf.briar.api.protocol.VerificationExecutor;
 import net.sf.briar.api.transport.ConnectionReader;
 import net.sf.briar.api.transport.ConnectionReaderFactory;
+import net.sf.briar.api.transport.ConnectionRegistry;
 import net.sf.briar.api.transport.ConnectionWriter;
 import net.sf.briar.api.transport.ConnectionWriterFactory;
 import net.sf.briar.api.transport.StreamTransportConnection;
@@ -59,11 +61,13 @@ abstract class StreamConnection implements DatabaseListener {
 	};
 
 	protected final DatabaseComponent db;
+	protected final ConnectionRegistry connRegistry;
 	protected final ConnectionReaderFactory connReaderFactory;
 	protected final ConnectionWriterFactory connWriterFactory;
 	protected final ProtocolReaderFactory protoReaderFactory;
 	protected final ProtocolWriterFactory protoWriterFactory;
 	protected final ContactId contactId;
+	protected final TransportId transportId;
 	protected final StreamTransportConnection transport;
 
 	private final Executor dbExecutor, verificationExecutor;
@@ -76,19 +80,22 @@ abstract class StreamConnection implements DatabaseListener {
 
 	StreamConnection(@DatabaseExecutor Executor dbExecutor,
 			@VerificationExecutor Executor verificationExecutor,
-			DatabaseComponent db, ConnectionReaderFactory connReaderFactory,
+			DatabaseComponent db, ConnectionRegistry connRegistry,
+			ConnectionReaderFactory connReaderFactory,
 			ConnectionWriterFactory connWriterFactory,
 			ProtocolReaderFactory protoReaderFactory,
 			ProtocolWriterFactory protoWriterFactory, ContactId contactId,
-			StreamTransportConnection transport) {
+			TransportId transportId, StreamTransportConnection transport) {
 		this.dbExecutor = dbExecutor;
 		this.verificationExecutor = verificationExecutor;
 		this.db = db;
+		this.connRegistry = connRegistry;
 		this.connReaderFactory = connReaderFactory;
 		this.connWriterFactory = connWriterFactory;
 		this.protoReaderFactory = protoReaderFactory;
 		this.protoWriterFactory = protoWriterFactory;
 		this.contactId = contactId;
+		this.transportId = transportId;
 		this.transport = transport;
 		canSendOffer = new AtomicBoolean(false);
 		disposed = new AtomicBoolean(false);
@@ -188,8 +195,9 @@ abstract class StreamConnection implements DatabaseListener {
 	}
 
 	void write() {
+		connRegistry.registerConnection(contactId, transportId);
+		db.addListener(this);
 		try {
-			db.addListener(this);
 			OutputStream out = createConnectionWriter().getOutputStream();
 			writer = protoWriterFactory.createProtocolWriter(out,
 					transport.shouldFlush());
@@ -217,6 +225,7 @@ abstract class StreamConnection implements DatabaseListener {
 			if(LOG.isLoggable(Level.WARNING)) LOG.warning(e.toString());
 			if(!disposed.getAndSet(true)) transport.dispose(true, true);
 		} finally {
+			connRegistry.unregisterConnection(contactId, transportId);
 			db.removeListener(this);
 		}
 	}

components/net/sf/briar/protocol/stream/StreamConnectionFactoryImpl.java

@@ -7,11 +7,13 @@ import net.sf.briar.api.db.DatabaseComponent;
 import net.sf.briar.api.db.DatabaseExecutor;
 import net.sf.briar.api.protocol.ProtocolReaderFactory;
 import net.sf.briar.api.protocol.ProtocolWriterFactory;
+import net.sf.briar.api.protocol.TransportId;
 import net.sf.briar.api.protocol.TransportIndex;
 import net.sf.briar.api.protocol.VerificationExecutor;
 import net.sf.briar.api.protocol.stream.StreamConnectionFactory;
 import net.sf.briar.api.transport.ConnectionContext;
 import net.sf.briar.api.transport.ConnectionReaderFactory;
+import net.sf.briar.api.transport.ConnectionRegistry;
 import net.sf.briar.api.transport.ConnectionWriterFactory;
 import net.sf.briar.api.transport.StreamTransportConnection;
 
@@ -21,6 +23,7 @@ class StreamConnectionFactoryImpl implements StreamConnectionFactory {
 
 	private final Executor dbExecutor, verificationExecutor;
 	private final DatabaseComponent db;
+	private final ConnectionRegistry connRegistry;
 	private final ConnectionReaderFactory connReaderFactory;
 	private final ConnectionWriterFactory connWriterFactory;
 	private final ProtocolReaderFactory protoReaderFactory;
@@ -29,24 +32,27 @@ class StreamConnectionFactoryImpl implements StreamConnectionFactory {
 	@Inject
 	StreamConnectionFactoryImpl(@DatabaseExecutor Executor dbExecutor,
 			@VerificationExecutor Executor verificationExecutor,
-			DatabaseComponent db, ConnectionReaderFactory connReaderFactory,
+			DatabaseComponent db, ConnectionRegistry connRegistry,
+			ConnectionReaderFactory connReaderFactory,
 			ConnectionWriterFactory connWriterFactory,
 			ProtocolReaderFactory protoReaderFactory,
 			ProtocolWriterFactory protoWriterFactory) {
 		this.dbExecutor = dbExecutor;
 		this.verificationExecutor = verificationExecutor;
 		this.db = db;
+		this.connRegistry = connRegistry;
 		this.connReaderFactory = connReaderFactory;
 		this.connWriterFactory = connWriterFactory;
 		this.protoReaderFactory = protoReaderFactory;
 		this.protoWriterFactory = protoWriterFactory;
 	}
 
-	public void createIncomingConnection(ConnectionContext ctx,
+	public void createIncomingConnection(ConnectionContext ctx, TransportId t,
 			StreamTransportConnection s, byte[] tag) {
 		final StreamConnection conn = new IncomingStreamConnection(dbExecutor,
-				verificationExecutor, db, connReaderFactory, connWriterFactory,
-				protoReaderFactory, protoWriterFactory, ctx, s, tag);
+				verificationExecutor, db, connRegistry, connReaderFactory,
+				connWriterFactory, protoReaderFactory, protoWriterFactory,
+				ctx, t, s, tag);
 		Runnable write = new Runnable() {
 			public void run() {
 				conn.write();
@@ -61,11 +67,12 @@ class StreamConnectionFactoryImpl implements StreamConnectionFactory {
 		new Thread(read).start();
 	}
 
-	public void createOutgoingConnection(ContactId c, TransportIndex i,
-			StreamTransportConnection s) {
+	public void createOutgoingConnection(ContactId c, TransportId t,
+			TransportIndex i, StreamTransportConnection s) {
 		final StreamConnection conn = new OutgoingStreamConnection(dbExecutor,
-				verificationExecutor, db, connReaderFactory, connWriterFactory,
-				protoReaderFactory, protoWriterFactory, c, i, s);
+				verificationExecutor, db, connRegistry, connReaderFactory,
+				connWriterFactory, protoReaderFactory, protoWriterFactory,
+				c, t, i, s);
 		Runnable write = new Runnable() {
 			public void run() {
 				conn.write();

components/net/sf/briar/transport/ConnectionDispatcherImpl.java

@@ -49,9 +49,9 @@ class ConnectionDispatcherImpl implements ConnectionDispatcher {
 		executor.execute(new DispatchBatchConnection(t, r));
 	}
 
-	public void dispatchWriter(ContactId c, TransportIndex i,
+	public void dispatchWriter(ContactId c, TransportId t, TransportIndex i,
 			BatchTransportWriter w) {
-		batchConnFactory.createOutgoingConnection(c, i, w);
+		batchConnFactory.createOutgoingConnection(c, t, i, w);
 	}
 
 	public void dispatchIncomingConnection(TransportId t,
@@ -59,9 +59,9 @@ class ConnectionDispatcherImpl implements ConnectionDispatcher {
 		executor.execute(new DispatchStreamConnection(t, s));
 	}
 
-	public void dispatchOutgoingConnection(ContactId c, TransportIndex i,
-			StreamTransportConnection s) {
-		streamConnFactory.createOutgoingConnection(c, i, s);
+	public void dispatchOutgoingConnection(ContactId c, TransportId t,
+			TransportIndex i, StreamTransportConnection s) {
+		streamConnFactory.createOutgoingConnection(c, t, i, s);
 	}
 
 	private byte[] readTag(InputStream in) throws IOException {
@@ -92,8 +92,8 @@ class ConnectionDispatcherImpl implements ConnectionDispatcher {
 				ConnectionContext ctx = recogniser.acceptConnection(transportId,
 						tag);
 				if(ctx == null) transport.dispose(false, false);
-				else batchConnFactory.createIncomingConnection(ctx, transport,
-						tag);
+				else batchConnFactory.createIncomingConnection(ctx, transportId,
+						transport, tag);
 			} catch(DbException e) {
 				if(LOG.isLoggable(Level.WARNING)) LOG.warning(e.toString());
 				transport.dispose(true, false);
@@ -121,8 +121,8 @@ class ConnectionDispatcherImpl implements ConnectionDispatcher {
 				ConnectionContext ctx = recogniser.acceptConnection(transportId,
 						tag);
 				if(ctx == null) transport.dispose(false, false);
-				else streamConnFactory.createIncomingConnection(ctx, transport,
-						tag);
+				else streamConnFactory.createIncomingConnection(ctx,
+						transportId, transport, tag);
 			} catch(DbException e) {
 				if(LOG.isLoggable(Level.WARNING)) LOG.warning(e.toString());
 				transport.dispose(true, false);

components/net/sf/briar/transport/ConnectionRegistryImpl.java

@@ -0,0 +1,53 @@
+package net.sf.briar.transport;
+
+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 net.sf.briar.api.ContactId;
+import net.sf.briar.api.protocol.TransportId;
+import net.sf.briar.api.transport.ConnectionRegistry;
+
+public class ConnectionRegistryImpl implements ConnectionRegistry {
+
+	// Locking: this
+	private final Map<TransportId, Map<ContactId, Integer>> connections;
+
+	ConnectionRegistryImpl() {
+		connections = new HashMap<TransportId, Map<ContactId, Integer>>();
+	}
+
+	public synchronized void registerConnection(ContactId c, TransportId t) {
+		Map<ContactId, Integer> m = connections.get(t);
+		if(m == null) {
+			m = new HashMap<ContactId, Integer>();
+			connections.put(t, m);
+		}
+		Integer count = m.get(c);
+		if(count == null) m.put(c, 1);
+		else m.put(c, count + 1);
+	}
+
+	public synchronized void unregisterConnection(ContactId c, TransportId t) {
+		Map<ContactId, Integer> m = connections.get(t);
+		if(m == null) throw new IllegalArgumentException();
+		Integer count = m.remove(c);
+		if(count == null) throw new IllegalArgumentException();
+		if(count == 1) {
+			if(m.isEmpty()) connections.remove(t);
+		} else {
+			m.put(c, count - 1);
+		}
+	}
+
+	public synchronized Collection<ContactId> getConnectedContacts(
+			TransportId t) {
+		Map<ContactId, Integer> m = connections.get(t);
+		if(m == null) return Collections.emptyList();
+		List<ContactId> keys = new ArrayList<ContactId>(m.keySet());
+		return Collections.unmodifiableList(keys);
+	}
+}

components/net/sf/briar/transport/TransportModule.java

@@ -8,6 +8,7 @@ import net.sf.briar.api.transport.ConnectionDispatcher;
 import net.sf.briar.api.transport.ConnectionReaderFactory;
 import net.sf.briar.api.transport.ConnectionRecogniser;
 import net.sf.briar.api.transport.ConnectionRecogniserExecutor;
+import net.sf.briar.api.transport.ConnectionRegistry;
 import net.sf.briar.api.transport.ConnectionWindowFactory;
 import net.sf.briar.api.transport.ConnectionWriterFactory;
 
@@ -23,6 +24,7 @@ public class TransportModule extends AbstractModule {
 		bind(ConnectionReaderFactory.class).to(
 				ConnectionReaderFactoryImpl.class);
 		bind(ConnectionRecogniser.class).to(ConnectionRecogniserImpl.class);
+		bind(ConnectionRegistry.class).toInstance(new ConnectionRegistryImpl());
 		bind(ConnectionWindowFactory.class).to(
 				ConnectionWindowFactoryImpl.class);
 		bind(ConnectionWriterFactory.class).to(