Update test class.

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

@@ -24,6 +24,7 @@ import java.util.concurrent.Executor;
 import javax.annotation.concurrent.Immutable;
 import javax.inject.Inject;
 
+import static android.os.Build.BRAND;
 import static org.briarproject.bramble.api.plugin.BluetoothConstants.ID;
 
 @Immutable
@@ -81,8 +82,12 @@ public class AndroidBluetoothPluginFactory implements DuplexPluginFactory {
 
 	@Override
 	public DuplexPlugin createPlugin(PluginCallback callback) {
+		// On Motorola devices, don't try to open multiple connections - the
+		// Bluetooth stack can't handle it
+		// TODO: Narrow this down to specific models/versions if possible
+		boolean singleConnection = "motorola".equalsIgnoreCase(BRAND);
 		BluetoothConnectionLimiter connectionLimiter =
-				new BluetoothConnectionLimiterImpl(eventBus);
+				new BluetoothConnectionLimiterImpl(eventBus, singleConnection);
 		BluetoothConnectionFactory<BluetoothSocket> connectionFactory =
 				new AndroidBluetoothConnectionFactory(connectionLimiter,
 						wakeLockManager, timeoutMonitor);

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

@@ -22,6 +22,8 @@ public abstract class AbstractDuplexTransportConnection
 	private final Writer writer;
 	private final AtomicBoolean halfClosed, closed;
 
+	private volatile boolean markedForClose = false;
+
 	protected AbstractDuplexTransportConnection(Plugin plugin) {
 		this.plugin = plugin;
 		reader = new Reader();
@@ -52,6 +54,16 @@ public abstract class AbstractDuplexTransportConnection
 		return remote;
 	}
 
+	@Override
+	public boolean isMarkedForClose() {
+		return markedForClose;
+	}
+
+	@Override
+	public void markForClose() {
+		markedForClose = true;
+	}
+
 	private class Reader implements TransportConnectionReader {
 
 		@Override

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

@@ -1,6 +1,7 @@
 package org.briarproject.bramble.api.plugin.duplex;
 
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.plugin.ConnectionHandler;
 import org.briarproject.bramble.api.plugin.TransportConnectionReader;
 import org.briarproject.bramble.api.plugin.TransportConnectionWriter;
 import org.briarproject.bramble.api.properties.TransportProperties;
@@ -30,4 +31,17 @@ public interface DuplexTransportConnection {
 	 * the remote peer.
 	 */
 	TransportProperties getRemoteProperties();
+
+	/**
+	 * Returns true if the connection should be closed immediately without
+	 * sending anything.
+	 */
+	boolean isMarkedForClose();
+
+	/**
+	 * Call this method before the connection is passed to its
+	 * {@link ConnectionHandler} if the connection should be closed immediately
+	 * without sending anything.
+	 */
+	void markForClose();
 }

bramble-core/src/main/java/org/briarproject/bramble/connection/DuplexSyncConnection.java

@@ -33,6 +33,7 @@ abstract class DuplexSyncConnection extends SyncConnection
 
 	final Executor ioExecutor;
 	final TransportId transportId;
+	final DuplexTransportConnection connection;
 	final TransportConnectionReader reader;
 	final TransportConnectionWriter writer;
 	final TransportProperties remote;
@@ -80,6 +81,7 @@ abstract class DuplexSyncConnection extends SyncConnection
 				transportPropertyManager);
 		this.ioExecutor = ioExecutor;
 		this.transportId = transportId;
+		this.connection = connection;
 		reader = connection.getReader();
 		writer = connection.getWriter();
 		remote = connection.getRemoteProperties();
@@ -96,6 +98,13 @@ abstract class DuplexSyncConnection extends SyncConnection
 		disposeOnError(writer);
 	}
 
+	void closeOutgoingStream(StreamContext ctx, TransportConnectionWriter w)
+			throws IOException {
+		StreamWriter streamWriter = streamWriterFactory.createStreamWriter(
+				w.getOutputStream(), ctx);
+		streamWriter.sendEndOfStream();
+	}
+
 	SyncSession createDuplexOutgoingSession(StreamContext ctx,
 			TransportConnectionWriter w, @Nullable Priority priority)
 			throws IOException {

bramble-core/src/main/java/org/briarproject/bramble/connection/IncomingDuplexSyncConnection.java

@@ -93,10 +93,16 @@ class IncomingDuplexSyncConnection extends DuplexSyncConnection
 			return;
 		}
 		try {
-			// Create and run the outgoing session
-			SyncSession out = createDuplexOutgoingSession(ctx, writer, null);
-			setOutgoingSession(out);
-			out.run();
+			if (connection.isMarkedForClose()) {
+				// Close the outgoing stream without sending anything
+				closeOutgoingStream(ctx, writer);
+			} else {
+				// Create and run the outgoing session
+				SyncSession out =
+						createDuplexOutgoingSession(ctx, writer, null);
+				setOutgoingSession(out);
+				out.run();
+			}
 			writer.dispose(false);
 		} catch (IOException e) {
 			logException(LOG, WARNING, e);

bramble-core/src/main/java/org/briarproject/bramble/connection/OutgoingDuplexSyncConnection.java

@@ -65,11 +65,16 @@ class OutgoingDuplexSyncConnection extends DuplexSyncConnection
 		Priority priority = generatePriority();
 		ioExecutor.execute(() -> runIncomingSession(priority));
 		try {
-			// Create and run the outgoing session
-			SyncSession out =
-					createDuplexOutgoingSession(ctx, writer, priority);
-			setOutgoingSession(out);
-			out.run();
+			if (connection.isMarkedForClose()) {
+				// Close the outgoing stream without sending anything
+				closeOutgoingStream(ctx, writer);
+			} else {
+				// Create and run the outgoing session
+				SyncSession out =
+						createDuplexOutgoingSession(ctx, writer, priority);
+				setOutgoingSession(out);
+				out.run();
+			}
 			writer.dispose(false);
 		} catch (IOException e) {
 			logException(LOG, WARNING, e);

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

@@ -23,7 +23,9 @@ interface BluetoothConnectionLimiter {
 	boolean canOpenContactConnection();
 
 	/**
-	 * Informs the limiter that the given connection has been opened.
+	 * Informs the limiter that the given connection has been opened. If the
+	 * connection is above the limit it will be
+	 * {@link DuplexTransportConnection#markForClose() marked for close}.
 	 */
 	void connectionOpened(DuplexTransportConnection conn);
 

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

@@ -24,6 +24,7 @@ class BluetoothConnectionLimiterImpl implements BluetoothConnectionLimiter {
 			getLogger(BluetoothConnectionLimiterImpl.class.getName());
 
 	private final EventBus eventBus;
+	private final boolean singleConnection;
 
 	private final Object lock = new Object();
 	@GuardedBy("lock")
@@ -32,8 +33,10 @@ class BluetoothConnectionLimiterImpl implements BluetoothConnectionLimiter {
 	@GuardedBy("lock")
 	private boolean keyAgreementInProgress = false;
 
-	BluetoothConnectionLimiterImpl(EventBus eventBus) {
+	BluetoothConnectionLimiterImpl(EventBus eventBus,
+			boolean singleConnection) {
 		this.eventBus = eventBus;
+		this.singleConnection = singleConnection;
 	}
 
 	@Override
@@ -59,6 +62,9 @@ class BluetoothConnectionLimiterImpl implements BluetoothConnectionLimiter {
 			if (keyAgreementInProgress) {
 				LOG.info("Can't open contact connection during key agreement");
 				return false;
+			} else if (singleConnection && !connections.isEmpty()) {
+				LOG.info("Can't open contact connection due to limit");
+				return false;
 			} else {
 				LOG.info("Can open contact connection");
 				return true;
@@ -68,12 +74,18 @@ class BluetoothConnectionLimiterImpl implements BluetoothConnectionLimiter {
 
 	@Override
 	public void connectionOpened(DuplexTransportConnection conn) {
+		boolean shouldClose = false;
 		synchronized (lock) {
 			connections.add(conn);
 			if (LOG.isLoggable(INFO)) {
 				LOG.info("Connection opened, " + connections.size() + " open");
 			}
+			if (singleConnection && connections.size() > 1) {
+				LOG.info("Marking connection for close");
+				shouldClose = true;
+			}
 		}
+		if (shouldClose) conn.markForClose();
 	}
 
 	@Override

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

@@ -43,6 +43,15 @@ public class TestDuplexTransportConnection
 		return new TransportProperties();
 	}
 
+	@Override
+	public boolean isMarkedForClose() {
+		return false;
+	}
+
+	@Override
+	public void markForClose() {
+	}
+
 	/**
 	 * Creates and returns a pair of TestDuplexTransportConnections that are
 	 * connected to each other.

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

@@ -65,7 +65,7 @@ public class JavaBluetoothPluginFactory implements DuplexPluginFactory {
 	@Override
 	public DuplexPlugin createPlugin(PluginCallback callback) {
 		BluetoothConnectionLimiter connectionLimiter =
-				new BluetoothConnectionLimiterImpl(eventBus);
+				new BluetoothConnectionLimiterImpl(eventBus, false);
 		BluetoothConnectionFactory<StreamConnection> connectionFactory =
 				new JavaBluetoothConnectionFactory(connectionLimiter,
 						timeoutMonitor);