Poll for connections in series, with a delay between attempts.

The delay reduces interference between Bluetooth and wifi.

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

@@ -9,6 +9,7 @@ import android.content.Context;
 import android.content.Intent;
 import android.content.IntentFilter;
 
+import org.briarproject.bramble.api.io.TimeoutMonitor;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.bramble.api.plugin.Backoff;
@@ -30,6 +31,7 @@ import java.util.concurrent.BlockingQueue;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.Executor;
 import java.util.concurrent.LinkedBlockingQueue;
+import java.util.concurrent.ScheduledExecutorService;
 import java.util.logging.Logger;
 
 import javax.annotation.Nullable;
@@ -76,11 +78,13 @@ class AndroidBluetoothPlugin extends BluetoothPlugin<BluetoothServerSocket> {
 	private volatile BluetoothAdapter adapter = null;
 
 	AndroidBluetoothPlugin(BluetoothConnectionLimiter connectionLimiter,
-			Executor ioExecutor, AndroidExecutor androidExecutor,
-			Context appContext, SecureRandom secureRandom, Clock clock,
-			Backoff backoff, PluginCallback callback, int maxLatency) {
-		super(connectionLimiter, ioExecutor, secureRandom, backoff, callback,
-				maxLatency);
+			TimeoutMonitor timeoutMonitor, Executor ioExecutor,
+			ScheduledExecutorService scheduler, SecureRandom secureRandom,
+			AndroidExecutor androidExecutor, Context appContext, Clock clock,
+			Backoff backoff, PluginCallback callback, int maxLatency,
+			int maxIdleTime) {
+		super(connectionLimiter, timeoutMonitor, ioExecutor, scheduler,
+				secureRandom, backoff, callback, maxLatency, maxIdleTime);
 		this.androidExecutor = androidExecutor;
 		this.appContext = appContext;
 		this.clock = clock;
@@ -172,9 +176,10 @@ class AndroidBluetoothPlugin extends BluetoothPlugin<BluetoothServerSocket> {
 		return wrapSocket(ss.accept());
 	}
 
-	private DuplexTransportConnection wrapSocket(BluetoothSocket s) {
-		return new AndroidBluetoothTransportConnection(this,
-				connectionLimiter, s);
+	private DuplexTransportConnection wrapSocket(BluetoothSocket s)
+			throws IOException {
+		return new AndroidBluetoothTransportConnection(this, connectionLimiter,
+				timeoutMonitor, s);
 	}
 
 	@Override

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

@@ -3,6 +3,7 @@ package org.briarproject.bramble.plugin.bluetooth;
 import android.content.Context;
 
 import org.briarproject.bramble.api.event.EventBus;
+import org.briarproject.bramble.api.io.TimeoutMonitor;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.Backoff;
 import org.briarproject.bramble.api.plugin.BackoffFactory;
@@ -15,6 +16,7 @@ import org.briarproject.bramble.api.system.Clock;
 
 import java.security.SecureRandom;
 import java.util.concurrent.Executor;
+import java.util.concurrent.ScheduledExecutorService;
 
 import javax.annotation.concurrent.Immutable;
 
@@ -25,28 +27,34 @@ import static org.briarproject.bramble.api.plugin.BluetoothConstants.ID;
 public class AndroidBluetoothPluginFactory implements DuplexPluginFactory {
 
 	private static final int MAX_LATENCY = 30 * 1000; // 30 seconds
+	private static final int MAX_IDLE_TIME = 30 * 1000; // 30 seconds
 	private static final int MIN_POLLING_INTERVAL = 60 * 1000; // 1 minute
 	private static final int MAX_POLLING_INTERVAL = 10 * 60 * 1000; // 10 mins
 	private static final double BACKOFF_BASE = 1.2;
 
 	private final Executor ioExecutor;
+	private final ScheduledExecutorService scheduler;
 	private final AndroidExecutor androidExecutor;
 	private final Context appContext;
 	private final SecureRandom secureRandom;
 	private final EventBus eventBus;
 	private final Clock clock;
+	private final TimeoutMonitor timeoutMonitor;
 	private final BackoffFactory backoffFactory;
 
 	public AndroidBluetoothPluginFactory(Executor ioExecutor,
-			AndroidExecutor androidExecutor, Context appContext,
-			SecureRandom secureRandom, EventBus eventBus, Clock clock,
+			ScheduledExecutorService scheduler, AndroidExecutor androidExecutor,
+			Context appContext, SecureRandom secureRandom, EventBus eventBus,
+			Clock clock, TimeoutMonitor timeoutMonitor,
 			BackoffFactory backoffFactory) {
 		this.ioExecutor = ioExecutor;
+		this.scheduler = scheduler;
 		this.androidExecutor = androidExecutor;
 		this.appContext = appContext;
 		this.secureRandom = secureRandom;
 		this.eventBus = eventBus;
 		this.clock = clock;
+		this.timeoutMonitor = timeoutMonitor;
 		this.backoffFactory = backoffFactory;
 	}
 
@@ -67,8 +75,9 @@ public class AndroidBluetoothPluginFactory implements DuplexPluginFactory {
 		Backoff backoff = backoffFactory.createBackoff(MIN_POLLING_INTERVAL,
 				MAX_POLLING_INTERVAL, BACKOFF_BASE);
 		AndroidBluetoothPlugin plugin = new AndroidBluetoothPlugin(
-				connectionLimiter, ioExecutor, androidExecutor, appContext,
-				secureRandom, clock, backoff, callback, MAX_LATENCY);
+				connectionLimiter, timeoutMonitor, ioExecutor, scheduler,
+				secureRandom, androidExecutor, appContext, clock, backoff,
+				callback, MAX_LATENCY, MAX_IDLE_TIME);
 		eventBus.addListener(plugin);
 		return plugin;
 	}

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

@@ -2,6 +2,7 @@ package org.briarproject.bramble.plugin.bluetooth;
 
 import android.bluetooth.BluetoothSocket;
 
+import org.briarproject.bramble.api.io.TimeoutMonitor;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.Plugin;
 import org.briarproject.bramble.api.plugin.duplex.AbstractDuplexTransportConnection;
@@ -17,22 +18,26 @@ import static org.briarproject.bramble.util.AndroidUtils.isValidBluetoothAddress
 class AndroidBluetoothTransportConnection
 		extends AbstractDuplexTransportConnection {
 
-	private final BluetoothConnectionLimiter connectionManager;
+	private final BluetoothConnectionLimiter connectionLimiter;
 	private final BluetoothSocket socket;
+	private final InputStream in;
 
 	AndroidBluetoothTransportConnection(Plugin plugin,
-			BluetoothConnectionLimiter connectionManager,
-			BluetoothSocket socket) {
+			BluetoothConnectionLimiter connectionLimiter,
+			TimeoutMonitor timeoutMonitor, BluetoothSocket socket)
+			throws IOException {
 		super(plugin);
-		this.connectionManager = connectionManager;
+		this.connectionLimiter = connectionLimiter;
 		this.socket = socket;
+		in = timeoutMonitor.createTimeoutInputStream(
+				socket.getInputStream(), plugin.getMaxIdleTime() * 2);
 		String address = socket.getRemoteDevice().getAddress();
 		if (isValidBluetoothAddress(address)) remote.put(PROP_ADDRESS, address);
 	}
 
 	@Override
-	protected InputStream getInputStream() throws IOException {
-		return socket.getInputStream();
+	protected InputStream getInputStream() {
+		return in;
 	}
 
 	@Override
@@ -45,7 +50,7 @@ class AndroidBluetoothTransportConnection
 		try {
 			socket.close();
 		} finally {
-			connectionManager.connectionClosed(this);
+			connectionLimiter.connectionClosed(this);
 		}
 	}
 }

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

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

bramble-api/src/main/java/org/briarproject/bramble/api/system/Clock.java

@@ -11,6 +11,11 @@ public interface Clock {
 	 */
 	long currentTimeMillis();
 
+	/**
+	 * @see System#nanoTime()
+	 */
+	long nanoTime();
+
 	/**
 	 * @see Thread#sleep(long)
 	 */

bramble-api/src/test/java/org/briarproject/bramble/test/ArrayClock.java

@@ -16,6 +16,11 @@ public class ArrayClock implements Clock {
 		return times[index++];
 	}
 
+	@Override
+	public long nanoTime() {
+		return times[index++] * 1_000_000;
+	}
+
 	@Override
 	public void sleep(long milliseconds) throws InterruptedException {
 		Thread.sleep(milliseconds);

bramble-api/src/test/java/org/briarproject/bramble/test/SettableClock.java

@@ -17,6 +17,11 @@ public class SettableClock implements Clock {
 		return time.get();
 	}
 
+	@Override
+	public long nanoTime() {
+		return time.get() * 1_000_000;
+	}
+
 	@Override
 	public void sleep(long milliseconds) throws InterruptedException {
 		Thread.sleep(milliseconds);

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

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

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

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

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

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

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

@@ -0,0 +1,96 @@
+package org.briarproject.bramble.io;
+
+import org.briarproject.bramble.api.io.TimeoutMonitor;
+import org.briarproject.bramble.api.lifecycle.IoExecutor;
+import org.briarproject.bramble.api.system.Clock;
+import org.briarproject.bramble.api.system.Scheduler;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.Executor;
+import java.util.concurrent.Future;
+import java.util.concurrent.ScheduledExecutorService;
+import java.util.logging.Logger;
+
+import javax.annotation.concurrent.GuardedBy;
+import javax.inject.Inject;
+
+import static java.util.concurrent.TimeUnit.MILLISECONDS;
+import static java.util.concurrent.TimeUnit.SECONDS;
+import static java.util.logging.Level.INFO;
+import static java.util.logging.Logger.getLogger;
+import static org.briarproject.bramble.util.LogUtils.logException;
+
+class TimeoutMonitorImpl implements TimeoutMonitor {
+
+	private static final Logger LOG =
+			getLogger(TimeoutMonitorImpl.class.getName());
+
+	private static final long CHECK_INTERVAL_MS = SECONDS.toMillis(10);
+
+	private final ScheduledExecutorService scheduler;
+	private final Executor ioExecutor;
+	private final Clock clock;
+	private final Object lock = new Object();
+	@GuardedBy("lock")
+	private final List<TimeoutInputStream> streams = new ArrayList<>();
+
+	@GuardedBy("lock")
+	private Future<?> task = null;
+
+	@Inject
+	TimeoutMonitorImpl(@Scheduler ScheduledExecutorService scheduler,
+			@IoExecutor Executor ioExecutor, Clock clock) {
+		this.scheduler = scheduler;
+		this.ioExecutor = ioExecutor;
+		this.clock = clock;
+	}
+
+	@Override
+	public InputStream createTimeoutInputStream(InputStream in,
+			long timeoutMs) {
+		TimeoutInputStream stream = new TimeoutInputStream(clock, in,
+				timeoutMs * 1_000_000, this::removeStream);
+		synchronized (lock) {
+			if (streams.isEmpty()) {
+				task = scheduler.scheduleWithFixedDelay(this::checkTimeouts,
+						CHECK_INTERVAL_MS, CHECK_INTERVAL_MS, MILLISECONDS);
+			}
+			streams.add(stream);
+		}
+		return stream;
+	}
+
+	private void removeStream(TimeoutInputStream stream) {
+		Future<?> toCancel = null;
+		synchronized (lock) {
+			if (streams.remove(stream) && streams.isEmpty()) {
+				toCancel = task;
+				task = null;
+			}
+		}
+		if (toCancel != null) toCancel.cancel(false);
+	}
+
+	@Scheduler
+	private void checkTimeouts() {
+		ioExecutor.execute(() -> {
+			List<TimeoutInputStream> snapshot;
+			synchronized (lock) {
+				snapshot = new ArrayList<>(streams);
+			}
+			for (TimeoutInputStream stream : snapshot) {
+				if (stream.hasTimedOut()) {
+					LOG.info("Input stream has timed out");
+					try {
+						stream.close();
+					} catch (IOException e) {
+						logException(LOG, INFO, e);
+					}
+				}
+			}
+		});
+	}
+}

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

@@ -5,6 +5,7 @@ import org.briarproject.bramble.api.Pair;
 import org.briarproject.bramble.api.data.BdfList;
 import org.briarproject.bramble.api.event.Event;
 import org.briarproject.bramble.api.event.EventListener;
+import org.briarproject.bramble.api.io.TimeoutMonitor;
 import org.briarproject.bramble.api.keyagreement.KeyAgreementConnection;
 import org.briarproject.bramble.api.keyagreement.KeyAgreementListener;
 import org.briarproject.bramble.api.keyagreement.event.KeyAgreementListeningEvent;
@@ -30,13 +31,17 @@ import org.briarproject.bramble.api.settings.event.SettingsUpdatedEvent;
 import java.io.IOException;
 import java.security.SecureRandom;
 import java.util.Collection;
+import java.util.LinkedList;
 import java.util.UUID;
 import java.util.concurrent.Executor;
+import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.logging.Logger;
 
 import javax.annotation.Nullable;
 
+import static java.util.concurrent.TimeUnit.MILLISECONDS;
+import static java.util.concurrent.TimeUnit.SECONDS;
 import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
 import static java.util.logging.Logger.getLogger;
@@ -59,13 +64,22 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 	private static final Logger LOG =
 			getLogger(BluetoothPlugin.class.getName());
 
+	/**
+	 * The delay between connection attempts when polling. This reduces
+	 * interference between Bluetooth and wifi.
+	 */
+	private static final long CONNECTION_ATTEMPT_INTERVAL_MS =
+			SECONDS.toMillis(5);
+
 	final BluetoothConnectionLimiter connectionLimiter;
+	final TimeoutMonitor timeoutMonitor;
 
 	private final Executor ioExecutor;
+	private final ScheduledExecutorService scheduler;
 	private final SecureRandom secureRandom;
 	private final Backoff backoff;
 	private final PluginCallback callback;
-	private final int maxLatency;
+	private final int maxLatency, maxIdleTime;
 	private final AtomicBoolean used = new AtomicBoolean(false);
 
 	private volatile boolean running = false, contactConnections = false;
@@ -105,14 +119,19 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 	abstract DuplexTransportConnection discoverAndConnect(String uuid);
 
 	BluetoothPlugin(BluetoothConnectionLimiter connectionLimiter,
-			Executor ioExecutor, SecureRandom secureRandom,
-			Backoff backoff, PluginCallback callback, int maxLatency) {
+			TimeoutMonitor timeoutMonitor, Executor ioExecutor,
+			ScheduledExecutorService scheduler, SecureRandom secureRandom,
+			Backoff backoff, PluginCallback callback, int maxLatency,
+			int maxIdleTime) {
 		this.connectionLimiter = connectionLimiter;
+		this.timeoutMonitor = timeoutMonitor;
 		this.ioExecutor = ioExecutor;
+		this.scheduler = scheduler;
 		this.secureRandom = secureRandom;
 		this.backoff = backoff;
 		this.callback = callback;
 		this.maxLatency = maxLatency;
+		this.maxIdleTime = maxIdleTime;
 	}
 
 	void onAdapterEnabled() {
@@ -141,8 +160,7 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 
 	@Override
 	public int getMaxIdleTime() {
-		// Bluetooth detects dead connections so we don't need keepalives
-		return Integer.MAX_VALUE;
+		return maxIdleTime;
 	}
 
 	@Override
@@ -264,21 +282,31 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 			properties) {
 		if (!isRunning() || !shouldAllowContactConnections()) return;
 		backoff.increment();
-		for (Pair<TransportProperties, ConnectionHandler> p : properties) {
-			connect(p.getFirst(), p.getSecond());
+		LinkedList<Pair<TransportProperties, ConnectionHandler>> connectable =
+				new LinkedList<>();
+		for (Pair<TransportProperties, ConnectionHandler> pair : properties) {
+			TransportProperties p = pair.getFirst();
+			if (isNullOrEmpty(p.get(PROP_ADDRESS))) continue;
+			if (isNullOrEmpty(p.get(PROP_UUID))) continue;
+			connectable.add(pair);
 		}
+		if (!connectable.isEmpty()) poll(connectable);
 	}
 
-	private void connect(TransportProperties p, ConnectionHandler h) {
-		String address = p.get(PROP_ADDRESS);
-		if (isNullOrEmpty(address)) return;
-		String uuid = p.get(PROP_UUID);
-		if (isNullOrEmpty(uuid)) return;
+	private void poll(LinkedList<Pair<TransportProperties, ConnectionHandler>>
+			connectable) {
 		ioExecutor.execute(() -> {
-			DuplexTransportConnection d = createConnection(p);
+			if (!isRunning() || !shouldAllowContactConnections()) return;
+			Pair<TransportProperties, ConnectionHandler> pair =
+					connectable.removeFirst();
+			DuplexTransportConnection d = createConnection(pair.getFirst());
 			if (d != null) {
 				backoff.reset();
-				h.handleConnection(d);
+				pair.getSecond().handleConnection(d);
+			}
+			if (!connectable.isEmpty()) {
+				scheduler.schedule(() -> poll(connectable),
+						CONNECTION_ATTEMPT_INTERVAL_MS, MILLISECONDS);
 			}
 		});
 	}

bramble-core/src/main/java/org/briarproject/bramble/system/SystemClock.java

@@ -12,6 +12,11 @@ public class SystemClock implements Clock {
 		return System.currentTimeMillis();
 	}
 
+	@Override
+	public long nanoTime() {
+		return System.nanoTime();
+	}
+
 	@Override
 	public void sleep(long milliseconds) throws InterruptedException {
 		Thread.sleep(milliseconds);

bramble-core/src/test/java/org/briarproject/bramble/db/JdbcDatabaseTest.java

@@ -2420,6 +2420,11 @@ public abstract class JdbcDatabaseTest extends BrambleTestCase {
 			return time;
 		}
 
+		@Override
+		public long nanoTime() {
+			return time * 1_000_000;
+		}
+
 		@Override
 		public void sleep(long milliseconds) throws InterruptedException {
 			Thread.sleep(milliseconds);

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

@@ -0,0 +1,143 @@
+package org.briarproject.bramble.io;
+
+import org.briarproject.bramble.test.BrambleTestCase;
+import org.briarproject.bramble.test.SettableClock;
+import org.junit.Before;
+import org.junit.Test;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.concurrent.atomic.AtomicLong;
+
+import static java.util.concurrent.TimeUnit.MINUTES;
+import static java.util.concurrent.TimeUnit.SECONDS;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
+
+public class TimeoutInputStreamTest extends BrambleTestCase {
+
+	private static final long TIMEOUT_MS = MINUTES.toMillis(1);
+
+	private final long now = System.currentTimeMillis();
+
+	private AtomicLong time;
+	private UnresponsiveInputStream in;
+	private AtomicBoolean listenerCalled;
+	private TimeoutInputStream stream;
+	private CountDownLatch readReturned;
+
+	@Before
+	public void setUp() {
+		time = new AtomicLong(now);
+		in = new UnresponsiveInputStream();
+		listenerCalled = new AtomicBoolean(false);
+		stream = new TimeoutInputStream(new SettableClock(time), in,
+				TIMEOUT_MS * 1_000_000, stream -> listenerCalled.set(true));
+		readReturned = new CountDownLatch(1);
+	}
+
+	@Test
+	public void testTimeoutIsReportedIfReadDoesNotReturn() throws Exception {
+		startReading();
+		try {
+			// The stream should not report a timeout
+			assertFalse(stream.hasTimedOut());
+
+			// Time passes
+			time.set(now + TIMEOUT_MS);
+
+			// The stream still shouldn't report a timeout
+			assertFalse(stream.hasTimedOut());
+
+			// Time passes
+			time.set(now + TIMEOUT_MS + 1);
+
+			// The stream should report a timeout
+			assertTrue(stream.hasTimedOut());
+
+			// The listener should not have been called yet
+			assertFalse(listenerCalled.get());
+
+			// Close the stream
+			stream.close();
+
+			// The listener should have been called
+			assertTrue(listenerCalled.get());
+		} finally {
+			// Allow the read to return
+			in.readFinished.countDown();
+		}
+	}
+
+	@Test
+	public void testTimeoutIsNotReportedIfReadReturns() throws Exception {
+		startReading();
+		try {
+			// The stream should not report a timeout
+			assertFalse(stream.hasTimedOut());
+
+			// Time passes
+			time.set(now + TIMEOUT_MS);
+
+			// The stream still shouldn't report a timeout
+			assertFalse(stream.hasTimedOut());
+
+			// Allow the read to finish and wait for it to return
+			in.readFinished.countDown();
+			readReturned.await(10, SECONDS);
+
+			// Time passes
+			time.set(now + TIMEOUT_MS + 1);
+
+			// The stream should not report a timeout as the read has returned
+			assertFalse(stream.hasTimedOut());
+
+			// The listener should not have been called yet
+			assertFalse(listenerCalled.get());
+
+			// Close the stream
+			stream.close();
+
+			// The listener should have been called
+			assertTrue(listenerCalled.get());
+		} finally {
+			// Allow the read to return in case an assertion was thrown
+			in.readFinished.countDown();
+		}
+	}
+
+	private void startReading() throws Exception {
+		// Start a background thread to read from the unresponsive stream
+		new Thread(() -> {
+			try {
+				assertEquals(123, stream.read());
+				readReturned.countDown();
+			} catch (IOException e) {
+				fail();
+			}
+		}).start();
+		// Wait for the background thread to start reading
+		assertTrue(in.readStarted.await(10, SECONDS));
+	}
+
+	private class UnresponsiveInputStream extends InputStream {
+
+		private final CountDownLatch readStarted = new CountDownLatch(1);
+		private final CountDownLatch readFinished = new CountDownLatch(1);
+
+		@Override
+		public int read() throws IOException {
+			readStarted.countDown();
+			try {
+				readFinished.await();
+				return 123;
+			} catch (InterruptedException e) {
+				throw new IOException(e);
+			}
+		}
+	}
+}

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

@@ -1,6 +1,7 @@
 package org.briarproject.bramble.plugin;
 
 import org.briarproject.bramble.api.event.EventBus;
+import org.briarproject.bramble.api.io.TimeoutMonitor;
 import org.briarproject.bramble.api.lifecycle.IoExecutor;
 import org.briarproject.bramble.api.lifecycle.ShutdownManager;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
@@ -9,6 +10,7 @@ import org.briarproject.bramble.api.plugin.PluginConfig;
 import org.briarproject.bramble.api.plugin.duplex.DuplexPluginFactory;
 import org.briarproject.bramble.api.plugin.simplex.SimplexPluginFactory;
 import org.briarproject.bramble.api.reliability.ReliabilityLayerFactory;
+import org.briarproject.bramble.api.system.Scheduler;
 import org.briarproject.bramble.plugin.bluetooth.JavaBluetoothPluginFactory;
 import org.briarproject.bramble.plugin.modem.ModemPluginFactory;
 import org.briarproject.bramble.plugin.tcp.LanTcpPluginFactory;
@@ -17,6 +19,7 @@ import org.briarproject.bramble.plugin.tcp.WanTcpPluginFactory;
 import java.security.SecureRandom;
 import java.util.Collection;
 import java.util.concurrent.Executor;
+import java.util.concurrent.ScheduledExecutorService;
 
 import dagger.Module;
 import dagger.Provides;
@@ -29,12 +32,14 @@ public class DesktopPluginModule extends PluginModule {
 
 	@Provides
 	PluginConfig getPluginConfig(@IoExecutor Executor ioExecutor,
+			@Scheduler ScheduledExecutorService scheduler,
 			SecureRandom random, BackoffFactory backoffFactory,
 			ReliabilityLayerFactory reliabilityFactory,
-			ShutdownManager shutdownManager, EventBus eventBus) {
-		DuplexPluginFactory bluetooth =
-				new JavaBluetoothPluginFactory(ioExecutor, random, eventBus,
-						backoffFactory);
+			ShutdownManager shutdownManager, EventBus eventBus,
+			TimeoutMonitor timeoutMonitor) {
+		DuplexPluginFactory bluetooth = new JavaBluetoothPluginFactory(
+				ioExecutor, scheduler, random, eventBus, timeoutMonitor,
+				backoffFactory);
 		DuplexPluginFactory modem = new ModemPluginFactory(ioExecutor,
 				reliabilityFactory);
 		DuplexPluginFactory lan = new LanTcpPluginFactory(ioExecutor,

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

@@ -1,5 +1,6 @@
 package org.briarproject.bramble.plugin.bluetooth;
 
+import org.briarproject.bramble.api.io.TimeoutMonitor;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.bramble.api.plugin.Backoff;
@@ -9,6 +10,7 @@ import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
 import java.io.IOException;
 import java.security.SecureRandom;
 import java.util.concurrent.Executor;
+import java.util.concurrent.ScheduledExecutorService;
 import java.util.logging.Logger;
 
 import javax.annotation.Nullable;
@@ -34,10 +36,12 @@ class JavaBluetoothPlugin extends BluetoothPlugin<StreamConnectionNotifier> {
 	private volatile LocalDevice localDevice = null;
 
 	JavaBluetoothPlugin(BluetoothConnectionLimiter connectionManager,
-			Executor ioExecutor, SecureRandom secureRandom,
-			Backoff backoff, PluginCallback callback, int maxLatency) {
-		super(connectionManager, ioExecutor, secureRandom, backoff, callback,
-				maxLatency);
+			TimeoutMonitor timeoutMonitor, Executor ioExecutor,
+			ScheduledExecutorService scheduler, SecureRandom secureRandom,
+			Backoff backoff, PluginCallback callback, int maxLatency,
+			int maxIdleTime) {
+		super(connectionManager, timeoutMonitor, ioExecutor, scheduler,
+				secureRandom, backoff, callback, maxLatency, maxIdleTime);
 	}
 
 	@Override
@@ -119,7 +123,9 @@ class JavaBluetoothPlugin extends BluetoothPlugin<StreamConnectionNotifier> {
 		return "btspp://" + address + ":" + uuid + ";name=RFCOMM";
 	}
 
-	private DuplexTransportConnection wrapSocket(StreamConnection s) {
-		return new JavaBluetoothTransportConnection(this, connectionLimiter, s);
+	private DuplexTransportConnection wrapSocket(StreamConnection s)
+			throws IOException {
+		return new JavaBluetoothTransportConnection(this, connectionLimiter,
+				timeoutMonitor, s);
 	}
 }

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

@@ -1,6 +1,7 @@
 package org.briarproject.bramble.plugin.bluetooth;
 
 import org.briarproject.bramble.api.event.EventBus;
+import org.briarproject.bramble.api.io.TimeoutMonitor;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.Backoff;
 import org.briarproject.bramble.api.plugin.BackoffFactory;
@@ -11,6 +12,7 @@ import org.briarproject.bramble.api.plugin.duplex.DuplexPluginFactory;
 
 import java.security.SecureRandom;
 import java.util.concurrent.Executor;
+import java.util.concurrent.ScheduledExecutorService;
 
 import javax.annotation.concurrent.Immutable;
 
@@ -21,22 +23,28 @@ import static org.briarproject.bramble.api.plugin.BluetoothConstants.ID;
 public class JavaBluetoothPluginFactory implements DuplexPluginFactory {
 
 	private static final int MAX_LATENCY = 30 * 1000; // 30 seconds
+	private static final int MAX_IDLE_TIME = 30 * 1000; // 30 seconds
 	private static final int MIN_POLLING_INTERVAL = 60 * 1000; // 1 minute
 	private static final int MAX_POLLING_INTERVAL = 10 * 60 * 1000; // 10 mins
 	private static final double BACKOFF_BASE = 1.2;
 
 	private final Executor ioExecutor;
+	private final ScheduledExecutorService scheduler;
 	private final SecureRandom secureRandom;
-	private final BackoffFactory backoffFactory;
 	private final EventBus eventBus;
+	private final TimeoutMonitor timeoutMonitor;
+	private final BackoffFactory backoffFactory;
 
 	public JavaBluetoothPluginFactory(Executor ioExecutor,
-			SecureRandom secureRandom, EventBus eventBus,
+			ScheduledExecutorService scheduler, SecureRandom secureRandom,
+			EventBus eventBus, TimeoutMonitor timeoutMonitor,
 			BackoffFactory backoffFactory) {
 		this.ioExecutor = ioExecutor;
+		this.scheduler = scheduler;
 		this.secureRandom = secureRandom;
-		this.backoffFactory = backoffFactory;
 		this.eventBus = eventBus;
+		this.timeoutMonitor = timeoutMonitor;
+		this.backoffFactory = backoffFactory;
 	}
 
 	@Override
@@ -56,7 +64,8 @@ public class JavaBluetoothPluginFactory implements DuplexPluginFactory {
 		Backoff backoff = backoffFactory.createBackoff(MIN_POLLING_INTERVAL,
 				MAX_POLLING_INTERVAL, BACKOFF_BASE);
 		JavaBluetoothPlugin plugin = new JavaBluetoothPlugin(connectionLimiter,
-				ioExecutor, secureRandom, backoff, callback, MAX_LATENCY);
+				timeoutMonitor, ioExecutor, scheduler, secureRandom, backoff,
+				callback, MAX_LATENCY, MAX_IDLE_TIME);
 		eventBus.addListener(plugin);
 		return plugin;
 	}

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

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

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

@@ -14,6 +14,7 @@ import org.briarproject.bramble.api.crypto.KeyStrengthener;
 import org.briarproject.bramble.api.crypto.PublicKey;
 import org.briarproject.bramble.api.db.DatabaseConfig;
 import org.briarproject.bramble.api.event.EventBus;
+import org.briarproject.bramble.api.io.TimeoutMonitor;
 import org.briarproject.bramble.api.lifecycle.IoExecutor;
 import org.briarproject.bramble.api.lifecycle.LifecycleManager;
 import org.briarproject.bramble.api.network.NetworkManager;
@@ -122,11 +123,12 @@ public class AppModule {
 			LocationUtils locationUtils, EventBus eventBus,
 			ResourceProvider resourceProvider,
 			CircumventionProvider circumventionProvider,
-			BatteryManager batteryManager, Clock clock) {
+			BatteryManager batteryManager, Clock clock,
+			TimeoutMonitor timeoutMonitor) {
 		Context appContext = app.getApplicationContext();
-		DuplexPluginFactory bluetooth =
-				new AndroidBluetoothPluginFactory(ioExecutor, androidExecutor,
-						appContext, random, eventBus, clock, backoffFactory);
+		DuplexPluginFactory bluetooth = new AndroidBluetoothPluginFactory(
+				ioExecutor, scheduler, androidExecutor, appContext, random,
+				eventBus, clock, timeoutMonitor, backoffFactory);
 		DuplexPluginFactory tor = new AndroidTorPluginFactory(ioExecutor,
 				scheduler, appContext, networkManager, locationUtils, eventBus,
 				torSocketFactory, backoffFactory, resourceProvider,