Updated java.library.path.

bramble-android/src/main/java/org/briarproject/bramble/BrambleAndroidModule.java

@@ -0,0 +1,13 @@
+package org.briarproject.bramble;
+
+import org.briarproject.bramble.plugin.AndroidPluginModule;
+import org.briarproject.bramble.system.AndroidSystemModule;
+
+import dagger.Module;
+
+@Module(includes = {
+		AndroidPluginModule.class,
+		AndroidSystemModule.class
+})
+public class BrambleAndroidModule {
+}

bramble-android/src/main/java/org/briarproject/bramble/api/system/AndroidExecutor.java

@@ -0,0 +1,33 @@
+package org.briarproject.bramble.api.system;
+
+import java.util.concurrent.Callable;
+import java.util.concurrent.Future;
+
+/**
+ * Enables background threads to make Android API calls that must be made from
+ * a thread with a message queue.
+ */
+public interface AndroidExecutor {
+
+	/**
+	 * Runs the given task on a background thread with a message queue and
+	 * returns a Future for getting the result.
+	 */
+	<V> Future<V> runOnBackgroundThread(Callable<V> c);
+
+	/**
+	 * Runs the given task on a background thread with a message queue.
+	 */
+	void runOnBackgroundThread(Runnable r);
+
+	/**
+	 * Runs the given task on the main UI thread and returns a Future for
+	 * getting the result.
+	 */
+	<V> Future<V> runOnUiThread(Callable<V> c);
+
+	/**
+	 * Runs the given task on the main UI thread.
+	 */
+	void runOnUiThread(Runnable r);
+}

bramble-android/src/main/java/org/briarproject/bramble/plugin/AndroidPluginModule.java

@@ -0,0 +1,65 @@
+package org.briarproject.bramble.plugin;
+
+import android.app.Application;
+import android.content.Context;
+
+import org.briarproject.bramble.api.event.EventBus;
+import org.briarproject.bramble.api.lifecycle.IoExecutor;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.plugin.BackoffFactory;
+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.reporting.DevReporter;
+import org.briarproject.bramble.api.system.AndroidExecutor;
+import org.briarproject.bramble.api.system.LocationUtils;
+import org.briarproject.bramble.plugin.droidtooth.DroidtoothPluginFactory;
+import org.briarproject.bramble.plugin.tcp.AndroidLanTcpPluginFactory;
+import org.briarproject.bramble.plugin.tor.TorPluginFactory;
+
+import java.security.SecureRandom;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.concurrent.Executor;
+
+import javax.net.SocketFactory;
+
+import dagger.Module;
+import dagger.Provides;
+
+@Module
+public class AndroidPluginModule {
+
+	@Provides
+	PluginConfig providePluginConfig(@IoExecutor Executor ioExecutor,
+			AndroidExecutor androidExecutor, SecureRandom random,
+			SocketFactory torSocketFactory, BackoffFactory backoffFactory,
+			Application app, LocationUtils locationUtils, DevReporter reporter,
+			EventBus eventBus) {
+		Context appContext = app.getApplicationContext();
+		DuplexPluginFactory bluetooth = new DroidtoothPluginFactory(ioExecutor,
+				androidExecutor, appContext, random, backoffFactory);
+		DuplexPluginFactory tor = new TorPluginFactory(ioExecutor, appContext,
+				locationUtils, reporter, eventBus, torSocketFactory,
+				backoffFactory);
+		DuplexPluginFactory lan = new AndroidLanTcpPluginFactory(ioExecutor,
+				backoffFactory, appContext);
+		final Collection<DuplexPluginFactory> duplex =
+				Arrays.asList(bluetooth, tor, lan);
+		@NotNullByDefault
+		PluginConfig pluginConfig = new PluginConfig() {
+
+			@Override
+			public Collection<DuplexPluginFactory> getDuplexFactories() {
+				return duplex;
+			}
+
+			@Override
+			public Collection<SimplexPluginFactory> getSimplexFactories() {
+				return Collections.emptyList();
+			}
+		};
+		return pluginConfig;
+	}
+}

bramble-android/src/main/java/org/briarproject/bramble/plugin/droidtooth/DroidtoothPlugin.java

@@ -0,0 +1,677 @@
+package org.briarproject.bramble.plugin.droidtooth;
+
+import android.bluetooth.BluetoothAdapter;
+import android.bluetooth.BluetoothDevice;
+import android.bluetooth.BluetoothServerSocket;
+import android.bluetooth.BluetoothSocket;
+import android.content.BroadcastReceiver;
+import android.content.Context;
+import android.content.Intent;
+import android.content.IntentFilter;
+
+import org.briarproject.bramble.api.FormatException;
+import org.briarproject.bramble.api.contact.ContactId;
+import org.briarproject.bramble.api.crypto.PseudoRandom;
+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.MethodsNotNullByDefault;
+import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
+import org.briarproject.bramble.api.plugin.Backoff;
+import org.briarproject.bramble.api.plugin.TransportId;
+import org.briarproject.bramble.api.plugin.duplex.DuplexPlugin;
+import org.briarproject.bramble.api.plugin.duplex.DuplexPluginCallback;
+import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
+import org.briarproject.bramble.api.properties.TransportProperties;
+import org.briarproject.bramble.api.system.AndroidExecutor;
+import org.briarproject.bramble.util.AndroidUtils;
+import org.briarproject.bramble.util.StringUtils;
+
+import java.io.Closeable;
+import java.io.IOException;
+import java.io.InputStream;
+import java.security.SecureRandom;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.List;
+import java.util.Map;
+import java.util.Map.Entry;
+import java.util.UUID;
+import java.util.concurrent.Callable;
+import java.util.concurrent.CompletionService;
+import java.util.concurrent.CopyOnWriteArrayList;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.Executor;
+import java.util.concurrent.ExecutorCompletionService;
+import java.util.concurrent.Future;
+import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.logging.Logger;
+
+import javax.annotation.Nullable;
+
+import static android.bluetooth.BluetoothAdapter.ACTION_SCAN_MODE_CHANGED;
+import static android.bluetooth.BluetoothAdapter.ACTION_STATE_CHANGED;
+import static android.bluetooth.BluetoothAdapter.EXTRA_SCAN_MODE;
+import static android.bluetooth.BluetoothAdapter.EXTRA_STATE;
+import static android.bluetooth.BluetoothAdapter.SCAN_MODE_CONNECTABLE;
+import static android.bluetooth.BluetoothAdapter.SCAN_MODE_CONNECTABLE_DISCOVERABLE;
+import static android.bluetooth.BluetoothAdapter.SCAN_MODE_NONE;
+import static android.bluetooth.BluetoothAdapter.STATE_OFF;
+import static android.bluetooth.BluetoothAdapter.STATE_ON;
+import static android.bluetooth.BluetoothDevice.EXTRA_DEVICE;
+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.TRANSPORT_ID_BLUETOOTH;
+import static org.briarproject.bramble.api.plugin.BluetoothConstants.ID;
+import static org.briarproject.bramble.api.plugin.BluetoothConstants.PROP_ADDRESS;
+import static org.briarproject.bramble.api.plugin.BluetoothConstants.PROP_UUID;
+import static org.briarproject.bramble.api.plugin.BluetoothConstants.UUID_BYTES;
+import static org.briarproject.bramble.util.PrivacyUtils.scrubMacAddress;
+
+@MethodsNotNullByDefault
+@ParametersNotNullByDefault
+class DroidtoothPlugin implements DuplexPlugin {
+
+	private static final Logger LOG =
+			Logger.getLogger(DroidtoothPlugin.class.getName());
+	private static final String FOUND =
+			"android.bluetooth.device.action.FOUND";
+	private static final String DISCOVERY_FINISHED =
+			"android.bluetooth.adapter.action.DISCOVERY_FINISHED";
+
+	private final Executor ioExecutor;
+	private final AndroidExecutor androidExecutor;
+	private final Context appContext;
+	private final SecureRandom secureRandom;
+	private final Backoff backoff;
+	private final DuplexPluginCallback callback;
+	private final int maxLatency;
+	private final AtomicBoolean used = new AtomicBoolean(false);
+
+	private volatile boolean running = false;
+	private volatile boolean wasEnabledByUs = false;
+	private volatile BluetoothStateReceiver receiver = null;
+	private volatile BluetoothServerSocket socket = null;
+
+	// Non-null if the plugin started successfully
+	private volatile BluetoothAdapter adapter = null;
+
+	DroidtoothPlugin(Executor ioExecutor, AndroidExecutor androidExecutor,
+			Context appContext, SecureRandom secureRandom, Backoff backoff,
+			DuplexPluginCallback callback, int maxLatency) {
+		this.ioExecutor = ioExecutor;
+		this.androidExecutor = androidExecutor;
+		this.appContext = appContext;
+		this.secureRandom = secureRandom;
+		this.backoff = backoff;
+		this.callback = callback;
+		this.maxLatency = maxLatency;
+	}
+
+	@Override
+	public TransportId getId() {
+		return ID;
+	}
+
+	@Override
+	public int getMaxLatency() {
+		return maxLatency;
+	}
+
+	@Override
+	public int getMaxIdleTime() {
+		// Bluetooth detects dead connections so we don't need keepalives
+		return Integer.MAX_VALUE;
+	}
+
+	@Override
+	public boolean start() throws IOException {
+		if (used.getAndSet(true)) throw new IllegalStateException();
+		// BluetoothAdapter.getDefaultAdapter() must be called on a thread
+		// with a message queue, so submit it to the AndroidExecutor
+		try {
+			adapter = androidExecutor.runOnBackgroundThread(
+					new Callable<BluetoothAdapter>() {
+						@Override
+						public BluetoothAdapter call() throws Exception {
+							return BluetoothAdapter.getDefaultAdapter();
+						}
+					}).get();
+		} catch (InterruptedException e) {
+			Thread.currentThread().interrupt();
+			throw new IOException("Interrupted while getting BluetoothAdapter");
+		} catch (ExecutionException e) {
+			throw new IOException(e);
+		}
+		if (adapter == null) {
+			LOG.info("Bluetooth is not supported");
+			return false;
+		}
+		running = true;
+		// Listen for changes to the Bluetooth state
+		IntentFilter filter = new IntentFilter();
+		filter.addAction(ACTION_STATE_CHANGED);
+		filter.addAction(ACTION_SCAN_MODE_CHANGED);
+		receiver = new BluetoothStateReceiver();
+		appContext.registerReceiver(receiver, filter);
+		// If Bluetooth is enabled, bind a socket
+		if (adapter.isEnabled()) {
+			bind();
+		} else {
+			// Enable Bluetooth if settings allow
+			if (callback.getSettings().getBoolean("enable", false)) {
+				wasEnabledByUs = true;
+				if (adapter.enable()) LOG.info("Enabling Bluetooth");
+				else LOG.info("Could not enable Bluetooth");
+			} else {
+				LOG.info("Not enabling Bluetooth");
+			}
+		}
+		return true;
+	}
+
+	private void bind() {
+		ioExecutor.execute(new Runnable() {
+			@Override
+			public void run() {
+				if (!isRunning()) return;
+				String address = AndroidUtils.getBluetoothAddress(appContext,
+						adapter);
+				if (LOG.isLoggable(INFO))
+					LOG.info("Local address " + scrubMacAddress(address));
+				if (!StringUtils.isNullOrEmpty(address)) {
+					// Advertise the Bluetooth address to contacts
+					TransportProperties p = new TransportProperties();
+					p.put(PROP_ADDRESS, address);
+					callback.mergeLocalProperties(p);
+				}
+				// Bind a server socket to accept connections from contacts
+				BluetoothServerSocket ss;
+				try {
+					ss = adapter.listenUsingInsecureRfcommWithServiceRecord(
+							"RFCOMM", getUuid());
+				} catch (IOException e) {
+					if (LOG.isLoggable(WARNING))
+						LOG.log(WARNING, e.toString(), e);
+					return;
+				}
+				if (!isRunning()) {
+					tryToClose(ss);
+					return;
+				}
+				LOG.info("Socket bound");
+				socket = ss;
+				backoff.reset();
+				callback.transportEnabled();
+				acceptContactConnections();
+			}
+		});
+	}
+
+	private UUID getUuid() {
+		String uuid = callback.getLocalProperties().get(PROP_UUID);
+		if (uuid == null) {
+			byte[] random = new byte[UUID_BYTES];
+			secureRandom.nextBytes(random);
+			uuid = UUID.nameUUIDFromBytes(random).toString();
+			TransportProperties p = new TransportProperties();
+			p.put(PROP_UUID, uuid);
+			callback.mergeLocalProperties(p);
+		}
+		return UUID.fromString(uuid);
+	}
+
+	private void tryToClose(@Nullable BluetoothServerSocket ss) {
+		try {
+			if (ss != null) ss.close();
+		} catch (IOException e) {
+			if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
+		} finally {
+			callback.transportDisabled();
+		}
+	}
+
+	private void acceptContactConnections() {
+		while (isRunning()) {
+			BluetoothSocket s;
+			try {
+				s = socket.accept();
+			} catch (IOException e) {
+				// This is expected when the socket is closed
+				if (LOG.isLoggable(INFO)) LOG.info(e.toString());
+				return;
+			}
+			if (LOG.isLoggable(INFO)) {
+				String address = s.getRemoteDevice().getAddress();
+				LOG.info("Connection from " + scrubMacAddress(address));
+			}
+			backoff.reset();
+			callback.incomingConnectionCreated(wrapSocket(s));
+		}
+	}
+
+	private DuplexTransportConnection wrapSocket(BluetoothSocket s) {
+		return new DroidtoothTransportConnection(this, s);
+	}
+
+	@Override
+	public void stop() {
+		running = false;
+		if (receiver != null) appContext.unregisterReceiver(receiver);
+		tryToClose(socket);
+		// Disable Bluetooth if we enabled it and it's still enabled
+		if (wasEnabledByUs && adapter.isEnabled()) {
+			if (adapter.disable()) LOG.info("Disabling Bluetooth");
+			else LOG.info("Could not disable Bluetooth");
+		}
+	}
+
+	@Override
+	public boolean isRunning() {
+		return running && adapter != null && adapter.isEnabled();
+	}
+
+	@Override
+	public boolean shouldPoll() {
+		return true;
+	}
+
+	@Override
+	public int getPollingInterval() {
+		return backoff.getPollingInterval();
+	}
+
+	@Override
+	public void poll(Collection<ContactId> connected) {
+		if (!isRunning()) return;
+		backoff.increment();
+		// Try to connect to known devices in parallel
+		Map<ContactId, TransportProperties> remote =
+				callback.getRemoteProperties();
+		for (Entry<ContactId, TransportProperties> e : remote.entrySet()) {
+			final ContactId c = e.getKey();
+			if (connected.contains(c)) continue;
+			final String address = e.getValue().get(PROP_ADDRESS);
+			if (StringUtils.isNullOrEmpty(address)) continue;
+			final String uuid = e.getValue().get(PROP_UUID);
+			if (StringUtils.isNullOrEmpty(uuid)) continue;
+			ioExecutor.execute(new Runnable() {
+				@Override
+				public void run() {
+					if (!running) return;
+					BluetoothSocket s = connect(address, uuid);
+					if (s != null) {
+						backoff.reset();
+						callback.outgoingConnectionCreated(c, wrapSocket(s));
+					}
+				}
+			});
+		}
+	}
+
+	@Nullable
+	private BluetoothSocket connect(String address, String uuid) {
+		// Validate the address
+		if (!BluetoothAdapter.checkBluetoothAddress(address)) {
+			if (LOG.isLoggable(WARNING))
+				// not scrubbing here to be able to figure out the problem
+				LOG.warning("Invalid address " + address);
+			return null;
+		}
+		// Validate the UUID
+		UUID u;
+		try {
+			u = UUID.fromString(uuid);
+		} catch (IllegalArgumentException e) {
+			if (LOG.isLoggable(WARNING)) LOG.warning("Invalid UUID " + uuid);
+			return null;
+		}
+		// Try to connect
+		BluetoothDevice d = adapter.getRemoteDevice(address);
+		BluetoothSocket s = null;
+		try {
+			s = d.createInsecureRfcommSocketToServiceRecord(u);
+			if (LOG.isLoggable(INFO))
+				LOG.info("Connecting to " + scrubMacAddress(address));
+			s.connect();
+			if (LOG.isLoggable(INFO))
+				LOG.info("Connected to " + scrubMacAddress(address));
+			return s;
+		} catch (IOException e) {
+			if (LOG.isLoggable(INFO))
+				LOG.info("Failed to connect to " + scrubMacAddress(address));
+			tryToClose(s);
+			return null;
+		}
+	}
+
+	private void tryToClose(@Nullable Closeable c) {
+		try {
+			if (c != null) c.close();
+		} catch (IOException e) {
+			if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
+		}
+	}
+
+	@Override
+	public DuplexTransportConnection createConnection(ContactId c) {
+		if (!isRunning()) return null;
+		TransportProperties p = callback.getRemoteProperties().get(c);
+		if (p == null) return null;
+		String address = p.get(PROP_ADDRESS);
+		if (StringUtils.isNullOrEmpty(address)) return null;
+		String uuid = p.get(PROP_UUID);
+		if (StringUtils.isNullOrEmpty(uuid)) return null;
+		BluetoothSocket s = connect(address, uuid);
+		if (s == null) return null;
+		return new DroidtoothTransportConnection(this, s);
+	}
+
+	@Override
+	public boolean supportsInvitations() {
+		return true;
+	}
+
+	@Override
+	public DuplexTransportConnection createInvitationConnection(PseudoRandom r,
+			long timeout, boolean alice) {
+		if (!isRunning()) return null;
+		// Use the invitation codes to generate the UUID
+		byte[] b = r.nextBytes(UUID_BYTES);
+		UUID uuid = UUID.nameUUIDFromBytes(b);
+		if (LOG.isLoggable(INFO)) LOG.info("Invitation UUID " + uuid);
+		// Bind a server socket for receiving invitation connections
+		BluetoothServerSocket ss;
+		try {
+			ss = adapter.listenUsingInsecureRfcommWithServiceRecord(
+					"RFCOMM", uuid);
+		} catch (IOException e) {
+			if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
+			return null;
+		}
+		// Create the background tasks
+		CompletionService<BluetoothSocket> complete =
+				new ExecutorCompletionService<>(ioExecutor);
+		List<Future<BluetoothSocket>> futures = new ArrayList<>();
+		if (alice) {
+			// Return the first connected socket
+			futures.add(complete.submit(new ListeningTask(ss)));
+			futures.add(complete.submit(new DiscoveryTask(uuid.toString())));
+		} else {
+			// Return the first socket with readable data
+			futures.add(complete.submit(new ReadableTask(
+					new ListeningTask(ss))));
+			futures.add(complete.submit(new ReadableTask(
+					new DiscoveryTask(uuid.toString()))));
+		}
+		BluetoothSocket chosen = null;
+		try {
+			Future<BluetoothSocket> f = complete.poll(timeout, MILLISECONDS);
+			if (f == null) return null; // No task completed within the timeout
+			chosen = f.get();
+			return new DroidtoothTransportConnection(this, chosen);
+		} catch (InterruptedException e) {
+			LOG.info("Interrupted while exchanging invitations");
+			Thread.currentThread().interrupt();
+			return null;
+		} catch (ExecutionException e) {
+			if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
+			return null;
+		} finally {
+			// Closing the socket will terminate the listener task
+			tryToClose(ss);
+			closeSockets(futures, chosen);
+		}
+	}
+
+	private void closeSockets(final List<Future<BluetoothSocket>> futures,
+			@Nullable final BluetoothSocket chosen) {
+		ioExecutor.execute(new Runnable() {
+			@Override
+			public void run() {
+				for (Future<BluetoothSocket> f : futures) {
+					try {
+						if (f.cancel(true)) {
+							LOG.info("Cancelled task");
+						} else {
+							BluetoothSocket s = f.get();
+							if (s != null && s != chosen) {
+								LOG.info("Closing unwanted socket");
+								s.close();
+							}
+						}
+					} catch (InterruptedException e) {
+						LOG.info("Interrupted while closing sockets");
+						return;
+					} catch (ExecutionException | IOException e) {
+						if (LOG.isLoggable(INFO)) LOG.info(e.toString());
+					}
+				}
+			}
+		});
+	}
+
+	@Override
+	public boolean supportsKeyAgreement() {
+		return true;
+	}
+
+	@Override
+	public KeyAgreementListener createKeyAgreementListener(byte[] commitment) {
+		if (!isRunning()) return null;
+		// There's no point listening if we can't discover our own address
+		String address = AndroidUtils.getBluetoothAddress(appContext, adapter);
+		if (address.isEmpty()) return null;
+		// No truncation necessary because COMMIT_LENGTH = 16
+		UUID uuid = UUID.nameUUIDFromBytes(commitment);
+		if (LOG.isLoggable(INFO)) LOG.info("Key agreement UUID " + uuid);
+		// Bind a server socket for receiving invitation connections
+		BluetoothServerSocket ss;
+		try {
+			ss = adapter.listenUsingInsecureRfcommWithServiceRecord(
+					"RFCOMM", uuid);
+		} catch (IOException e) {
+			if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
+			return null;
+		}
+		BdfList descriptor = new BdfList();
+		descriptor.add(TRANSPORT_ID_BLUETOOTH);
+		descriptor.add(StringUtils.macToBytes(address));
+		return new BluetoothKeyAgreementListener(descriptor, ss);
+	}
+
+	@Override
+	public DuplexTransportConnection createKeyAgreementConnection(
+			byte[] commitment, BdfList descriptor, long timeout) {
+		if (!isRunning()) return null;
+		String address;
+		try {
+			address = parseAddress(descriptor);
+		} catch (FormatException e) {
+			LOG.info("Invalid address in key agreement descriptor");
+			return null;
+		}
+		// No truncation necessary because COMMIT_LENGTH = 16
+		UUID uuid = UUID.nameUUIDFromBytes(commitment);
+		if (LOG.isLoggable(INFO))
+			LOG.info("Connecting to key agreement UUID " + uuid);
+		BluetoothSocket s = connect(address, uuid.toString());
+		if (s == null) return null;
+		return new DroidtoothTransportConnection(this, s);
+	}
+
+	private String parseAddress(BdfList descriptor) throws FormatException {
+		byte[] mac = descriptor.getRaw(1);
+		if (mac.length != 6) throw new FormatException();
+		return StringUtils.macToString(mac);
+	}
+
+	private class BluetoothStateReceiver extends BroadcastReceiver {
+
+		@Override
+		public void onReceive(Context ctx, Intent intent) {
+			int state = intent.getIntExtra(EXTRA_STATE, 0);
+			if (state == STATE_ON) {
+				LOG.info("Bluetooth enabled");
+				bind();
+			} else if (state == STATE_OFF) {
+				LOG.info("Bluetooth disabled");
+				tryToClose(socket);
+			}
+			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");
+			}
+		}
+	}
+
+	private class DiscoveryTask implements Callable<BluetoothSocket> {
+
+		private final String uuid;
+
+		private DiscoveryTask(String uuid) {
+			this.uuid = uuid;
+		}
+
+		@Override
+		public BluetoothSocket call() throws Exception {
+			// Repeat discovery until we connect or get interrupted
+			while (true) {
+				// Discover nearby devices
+				LOG.info("Discovering nearby devices");
+				List<String> addresses = discoverDevices();
+				if (addresses.isEmpty()) {
+					LOG.info("No devices discovered");
+					continue;
+				}
+				// Connect to any device with the right UUID
+				for (String address : addresses) {
+					BluetoothSocket s = connect(address, uuid);
+					if (s != null) {
+						LOG.info("Outgoing connection");
+						return s;
+					}
+				}
+			}
+		}
+
+		private List<String> discoverDevices() throws InterruptedException {
+			IntentFilter filter = new IntentFilter();
+			filter.addAction(FOUND);
+			filter.addAction(DISCOVERY_FINISHED);
+			DiscoveryReceiver disco = new DiscoveryReceiver();
+			appContext.registerReceiver(disco, filter);
+			LOG.info("Starting discovery");
+			adapter.startDiscovery();
+			return disco.waitForAddresses();
+		}
+	}
+
+	private static class DiscoveryReceiver extends BroadcastReceiver {
+
+		private final CountDownLatch finished = new CountDownLatch(1);
+		private final List<String> addresses = new CopyOnWriteArrayList<>();
+
+		@Override
+		public void onReceive(Context ctx, Intent intent) {
+			String action = intent.getAction();
+			if (action.equals(DISCOVERY_FINISHED)) {
+				LOG.info("Discovery finished");
+				ctx.unregisterReceiver(this);
+				finished.countDown();
+			} else if (action.equals(FOUND)) {
+				BluetoothDevice d = intent.getParcelableExtra(EXTRA_DEVICE);
+				if (LOG.isLoggable(INFO))
+					LOG.info("Discovered device: " +
+							scrubMacAddress(d.getAddress()));
+				addresses.add(d.getAddress());
+			}
+		}
+
+		private List<String> waitForAddresses() throws InterruptedException {
+			finished.await();
+			List<String> shuffled = new ArrayList<>(addresses);
+			Collections.shuffle(shuffled);
+			return shuffled;
+		}
+	}
+
+	private static class ListeningTask implements Callable<BluetoothSocket> {
+
+		private final BluetoothServerSocket serverSocket;
+
+		private ListeningTask(BluetoothServerSocket serverSocket) {
+			this.serverSocket = serverSocket;
+		}
+
+		@Override
+		public BluetoothSocket call() throws IOException {
+			BluetoothSocket s = serverSocket.accept();
+			LOG.info("Incoming connection");
+			return s;
+		}
+	}
+
+	private static class ReadableTask implements Callable<BluetoothSocket> {
+
+		private final Callable<BluetoothSocket> connectionTask;
+
+		private ReadableTask(Callable<BluetoothSocket> connectionTask) {
+			this.connectionTask = connectionTask;
+		}
+
+		@Override
+		public BluetoothSocket call() throws Exception {
+			BluetoothSocket s = connectionTask.call();
+			InputStream in = s.getInputStream();
+			while (in.available() == 0) {
+				LOG.info("Waiting for data");
+				Thread.sleep(1000);
+			}
+			LOG.info("Data available");
+			return s;
+		}
+	}
+
+	private class BluetoothKeyAgreementListener extends KeyAgreementListener {
+
+		private final BluetoothServerSocket ss;
+
+		private BluetoothKeyAgreementListener(BdfList descriptor,
+				BluetoothServerSocket ss) {
+			super(descriptor);
+			this.ss = ss;
+		}
+
+		@Override
+		public Callable<KeyAgreementConnection> listen() {
+			return new Callable<KeyAgreementConnection>() {
+				@Override
+				public KeyAgreementConnection call() throws IOException {
+					BluetoothSocket s = ss.accept();
+					if (LOG.isLoggable(INFO))
+						LOG.info(ID.getString() + ": Incoming connection");
+					return new KeyAgreementConnection(
+							new DroidtoothTransportConnection(
+									DroidtoothPlugin.this, s), ID);
+				}
+			};
+		}
+
+		@Override
+		public void close() {
+			try {
+				ss.close();
+			} catch (IOException e) {
+				if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
+			}
+		}
+	}
+}

bramble-android/src/main/java/org/briarproject/bramble/plugin/droidtooth/DroidtoothPluginFactory.java

@@ -0,0 +1,63 @@
+package org.briarproject.bramble.plugin.droidtooth;
+
+import android.content.Context;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.plugin.Backoff;
+import org.briarproject.bramble.api.plugin.BackoffFactory;
+import org.briarproject.bramble.api.plugin.TransportId;
+import org.briarproject.bramble.api.plugin.duplex.DuplexPlugin;
+import org.briarproject.bramble.api.plugin.duplex.DuplexPluginCallback;
+import org.briarproject.bramble.api.plugin.duplex.DuplexPluginFactory;
+import org.briarproject.bramble.api.system.AndroidExecutor;
+
+import java.security.SecureRandom;
+import java.util.concurrent.Executor;
+
+import javax.annotation.concurrent.Immutable;
+
+import static org.briarproject.bramble.api.plugin.BluetoothConstants.ID;
+
+@Immutable
+@NotNullByDefault
+public class DroidtoothPluginFactory implements DuplexPluginFactory {
+
+	private static final int MAX_LATENCY = 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 AndroidExecutor androidExecutor;
+	private final Context appContext;
+	private final SecureRandom secureRandom;
+	private final BackoffFactory backoffFactory;
+
+	public DroidtoothPluginFactory(Executor ioExecutor,
+			AndroidExecutor androidExecutor, Context appContext,
+			SecureRandom secureRandom, BackoffFactory backoffFactory) {
+		this.ioExecutor = ioExecutor;
+		this.androidExecutor = androidExecutor;
+		this.appContext = appContext;
+		this.secureRandom = secureRandom;
+		this.backoffFactory = backoffFactory;
+	}
+
+	@Override
+	public TransportId getId() {
+		return ID;
+	}
+
+	@Override
+	public int getMaxLatency() {
+		return MAX_LATENCY;
+	}
+
+	@Override
+	public DuplexPlugin createPlugin(DuplexPluginCallback callback) {
+		Backoff backoff = backoffFactory.createBackoff(MIN_POLLING_INTERVAL,
+				MAX_POLLING_INTERVAL, BACKOFF_BASE);
+		return new DroidtoothPlugin(ioExecutor, androidExecutor, appContext,
+				secureRandom, backoff, callback, MAX_LATENCY);
+	}
+}

bramble-android/src/main/java/org/briarproject/bramble/plugin/droidtooth/DroidtoothTransportConnection.java

@@ -0,0 +1,37 @@
+package org.briarproject.bramble.plugin.droidtooth;
+
+import android.bluetooth.BluetoothSocket;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.plugin.Plugin;
+import org.briarproject.bramble.api.plugin.duplex.AbstractDuplexTransportConnection;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+
+@NotNullByDefault
+class DroidtoothTransportConnection extends AbstractDuplexTransportConnection {
+
+	private final BluetoothSocket socket;
+
+	DroidtoothTransportConnection(Plugin plugin, BluetoothSocket socket) {
+		super(plugin);
+		this.socket = socket;
+	}
+
+	@Override
+	protected InputStream getInputStream() throws IOException {
+		return socket.getInputStream();
+	}
+
+	@Override
+	protected OutputStream getOutputStream() throws IOException {
+		return socket.getOutputStream();
+	}
+
+	@Override
+	protected void closeConnection(boolean exception) throws IOException {
+		socket.close();
+	}
+}

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

@@ -0,0 +1,77 @@
+package org.briarproject.bramble.plugin.tcp;
+
+import android.content.BroadcastReceiver;
+import android.content.Context;
+import android.content.Intent;
+import android.content.IntentFilter;
+import android.net.ConnectivityManager;
+import android.net.NetworkInfo;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.plugin.Backoff;
+import org.briarproject.bramble.api.plugin.duplex.DuplexPluginCallback;
+
+import java.util.concurrent.Executor;
+import java.util.logging.Logger;
+
+import javax.annotation.Nullable;
+
+import static android.content.Context.CONNECTIVITY_SERVICE;
+import static android.net.ConnectivityManager.CONNECTIVITY_ACTION;
+import static android.net.ConnectivityManager.TYPE_WIFI;
+
+@NotNullByDefault
+class AndroidLanTcpPlugin extends LanTcpPlugin {
+
+	private static final Logger LOG =
+			Logger.getLogger(AndroidLanTcpPlugin.class.getName());
+
+	private final Context appContext;
+
+	@Nullable
+	private volatile BroadcastReceiver networkStateReceiver = null;
+
+	AndroidLanTcpPlugin(Executor ioExecutor, Backoff backoff,
+			Context appContext, DuplexPluginCallback callback, int maxLatency,
+			int maxIdleTime) {
+		super(ioExecutor, backoff, callback, maxLatency, maxIdleTime);
+		this.appContext = appContext;
+	}
+
+	@Override
+	public boolean start() {
+		if (used.getAndSet(true)) throw new IllegalStateException();
+		running = true;
+		// Register to receive network status events
+		networkStateReceiver = new NetworkStateReceiver();
+		IntentFilter filter = new IntentFilter(CONNECTIVITY_ACTION);
+		appContext.registerReceiver(networkStateReceiver, filter);
+		return true;
+	}
+
+	@Override
+	public void stop() {
+		running = false;
+		if (networkStateReceiver != null)
+			appContext.unregisterReceiver(networkStateReceiver);
+		tryToClose(socket);
+	}
+
+	private class NetworkStateReceiver extends BroadcastReceiver {
+
+		@Override
+		public void onReceive(Context ctx, Intent i) {
+			if (!running) return;
+			Object o = ctx.getSystemService(CONNECTIVITY_SERVICE);
+			ConnectivityManager cm = (ConnectivityManager) o;
+			NetworkInfo net = cm.getActiveNetworkInfo();
+			if (net != null && net.getType() == TYPE_WIFI && net.isConnected()) {
+				LOG.info("Connected to Wi-Fi");
+				if (socket == null || socket.isClosed()) bind();
+			} else {
+				LOG.info("Not connected to Wi-Fi");
+				tryToClose(socket);
+			}
+		}
+	}
+}

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

@@ -0,0 +1,57 @@
+package org.briarproject.bramble.plugin.tcp;
+
+import android.content.Context;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.plugin.Backoff;
+import org.briarproject.bramble.api.plugin.BackoffFactory;
+import org.briarproject.bramble.api.plugin.TransportId;
+import org.briarproject.bramble.api.plugin.duplex.DuplexPlugin;
+import org.briarproject.bramble.api.plugin.duplex.DuplexPluginCallback;
+import org.briarproject.bramble.api.plugin.duplex.DuplexPluginFactory;
+
+import java.util.concurrent.Executor;
+
+import javax.annotation.concurrent.Immutable;
+
+import static org.briarproject.bramble.api.plugin.LanTcpConstants.ID;
+
+@Immutable
+@NotNullByDefault
+public class AndroidLanTcpPluginFactory implements DuplexPluginFactory {
+
+	private static final int MAX_LATENCY = 30 * 1000; // 30 seconds
+	private static final int MAX_IDLE_TIME = 30 * 1000; // 30 seconds
+	private static final int MIN_POLLING_INTERVAL = 60 * 1000; // 1 minute
+	private static final int MAX_POLLING_INTERVAL = 10 * 60 * 1000; // 10 mins
+	private static final double BACKOFF_BASE = 1.2;
+
+	private final Executor ioExecutor;
+	private final BackoffFactory backoffFactory;
+	private final Context appContext;
+
+	public AndroidLanTcpPluginFactory(Executor ioExecutor,
+			BackoffFactory backoffFactory, Context appContext) {
+		this.ioExecutor = ioExecutor;
+		this.backoffFactory = backoffFactory;
+		this.appContext = appContext;
+	}
+
+	@Override
+	public TransportId getId() {
+		return ID;
+	}
+
+	@Override
+	public int getMaxLatency() {
+		return MAX_LATENCY;
+	}
+
+	@Override
+	public DuplexPlugin createPlugin(DuplexPluginCallback callback) {
+		Backoff backoff = backoffFactory.createBackoff(MIN_POLLING_INTERVAL,
+				MAX_POLLING_INTERVAL, BACKOFF_BASE);
+		return new AndroidLanTcpPlugin(ioExecutor, backoff, appContext,
+				callback, MAX_LATENCY, MAX_IDLE_TIME);
+	}
+}

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

@@ -0,0 +1,18 @@
+package org.briarproject.bramble.plugin.tor;
+
+import java.util.Arrays;
+import java.util.HashSet;
+import java.util.Set;
+
+class TorNetworkMetadata {
+
+	// See https://en.wikipedia.org/wiki/ISO_3166-1_alpha-2
+	// and https://trac.torproject.org/projects/tor/wiki/doc/OONI/censorshipwiki
+	// TODO: get a more complete list
+	private static final Set<String> BLOCKED_IN_COUNTRIES =
+			new HashSet<>(Arrays.asList("CN", "IR", "SY", "ZZ"));
+
+	static boolean isTorProbablyBlocked(String countryCode) {
+		return BLOCKED_IN_COUNTRIES.contains(countryCode);
+	}
+}

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

@@ -0,0 +1,750 @@
+package org.briarproject.bramble.plugin.tor;
+
+import android.content.BroadcastReceiver;
+import android.content.Context;
+import android.content.Intent;
+import android.content.IntentFilter;
+import android.content.pm.PackageInfo;
+import android.content.pm.PackageManager;
+import android.content.pm.PackageManager.NameNotFoundException;
+import android.content.res.Resources;
+import android.net.ConnectivityManager;
+import android.net.NetworkInfo;
+import android.os.FileObserver;
+import android.os.PowerManager;
+
+import net.freehaven.tor.control.EventHandler;
+import net.freehaven.tor.control.TorControlConnection;
+
+import org.briarproject.bramble.api.contact.ContactId;
+import org.briarproject.bramble.api.crypto.PseudoRandom;
+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.keyagreement.KeyAgreementListener;
+import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
+import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
+import org.briarproject.bramble.api.plugin.Backoff;
+import org.briarproject.bramble.api.plugin.TorConstants;
+import org.briarproject.bramble.api.plugin.TransportId;
+import org.briarproject.bramble.api.plugin.duplex.DuplexPlugin;
+import org.briarproject.bramble.api.plugin.duplex.DuplexPluginCallback;
+import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
+import org.briarproject.bramble.api.properties.TransportProperties;
+import org.briarproject.bramble.api.reporting.DevReporter;
+import org.briarproject.bramble.api.settings.Settings;
+import org.briarproject.bramble.api.settings.event.SettingsUpdatedEvent;
+import org.briarproject.bramble.api.system.LocationUtils;
+import org.briarproject.bramble.util.AndroidUtils;
+import org.briarproject.bramble.util.IoUtils;
+import org.briarproject.bramble.util.StringUtils;
+
+import java.io.Closeable;
+import java.io.EOFException;
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.net.InetSocketAddress;
+import java.net.ServerSocket;
+import java.net.Socket;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.List;
+import java.util.Map;
+import java.util.Scanner;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.Executor;
+import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.logging.Logger;
+import java.util.regex.Pattern;
+import java.util.zip.ZipInputStream;
+
+import javax.annotation.Nullable;
+import javax.net.SocketFactory;
+
+import static android.content.Context.CONNECTIVITY_SERVICE;
+import static android.content.Context.MODE_PRIVATE;
+import static android.content.Context.POWER_SERVICE;
+import static android.net.ConnectivityManager.CONNECTIVITY_ACTION;
+import static android.net.ConnectivityManager.TYPE_WIFI;
+import static android.os.PowerManager.PARTIAL_WAKE_LOCK;
+import static java.util.concurrent.TimeUnit.MILLISECONDS;
+import static java.util.logging.Level.INFO;
+import static java.util.logging.Level.WARNING;
+import static net.freehaven.tor.control.TorControlCommands.HS_ADDRESS;
+import static net.freehaven.tor.control.TorControlCommands.HS_PRIVKEY;
+import static org.briarproject.bramble.api.plugin.TorConstants.CONTROL_PORT;
+import static org.briarproject.bramble.util.PrivacyUtils.scrubOnion;
+
+@MethodsNotNullByDefault
+@ParametersNotNullByDefault
+class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
+
+	private static final String PROP_ONION = "onion";
+	private static final String[] EVENTS = {
+			"CIRC", "ORCONN", "HS_DESC", "NOTICE", "WARN", "ERR"
+	};
+	private static final String OWNER = "__OwningControllerProcess";
+	private static final int COOKIE_TIMEOUT = 3000; // Milliseconds
+	private static final Pattern ONION = Pattern.compile("[a-z2-7]{16}");
+	private static final Logger LOG =
+			Logger.getLogger(TorPlugin.class.getName());
+
+	private final Executor ioExecutor;
+	private final Context appContext;
+	private final LocationUtils locationUtils;
+	private final DevReporter reporter;
+	private final SocketFactory torSocketFactory;
+	private final Backoff backoff;
+	private final DuplexPluginCallback callback;
+	private final String architecture;
+	private final int maxLatency, maxIdleTime, socketTimeout;
+	private final ConnectionStatus connectionStatus;
+	private final File torDirectory, torFile, geoIpFile, configFile;
+	private final File doneFile, cookieFile;
+	private final PowerManager.WakeLock wakeLock;
+	private final AtomicBoolean used = new AtomicBoolean(false);
+
+	private volatile boolean running = false;
+	private volatile ServerSocket socket = null;
+	private volatile Socket controlSocket = null;
+	private volatile TorControlConnection controlConnection = null;
+	private volatile BroadcastReceiver networkStateReceiver = null;
+
+	TorPlugin(Executor ioExecutor, Context appContext,
+			LocationUtils locationUtils, DevReporter reporter,
+			SocketFactory torSocketFactory, Backoff backoff,
+			DuplexPluginCallback callback, String architecture, int maxLatency,
+			int maxIdleTime) {
+		this.ioExecutor = ioExecutor;
+		this.appContext = appContext;
+		this.locationUtils = locationUtils;
+		this.reporter = reporter;
+		this.torSocketFactory = torSocketFactory;
+		this.backoff = backoff;
+		this.callback = callback;
+		this.architecture = architecture;
+		this.maxLatency = maxLatency;
+		this.maxIdleTime = maxIdleTime;
+		if (maxIdleTime > Integer.MAX_VALUE / 2)
+			socketTimeout = Integer.MAX_VALUE;
+		else socketTimeout = maxIdleTime * 2;
+		connectionStatus = new ConnectionStatus();
+		torDirectory = appContext.getDir("tor", MODE_PRIVATE);
+		torFile = new File(torDirectory, "tor");
+		geoIpFile = new File(torDirectory, "geoip");
+		configFile = new File(torDirectory, "torrc");
+		doneFile = new File(torDirectory, "done");
+		cookieFile = new File(torDirectory, ".tor/control_auth_cookie");
+		Object o = appContext.getSystemService(POWER_SERVICE);
+		PowerManager pm = (PowerManager) o;
+		wakeLock = pm.newWakeLock(PARTIAL_WAKE_LOCK, "TorPlugin");
+		wakeLock.setReferenceCounted(false);
+	}
+
+	@Override
+	public TransportId getId() {
+		return TorConstants.ID;
+	}
+
+	@Override
+	public int getMaxLatency() {
+		return maxLatency;
+	}
+
+	@Override
+	public int getMaxIdleTime() {
+		return maxIdleTime;
+	}
+
+	@Override
+	public boolean start() throws IOException {
+		if (used.getAndSet(true)) throw new IllegalStateException();
+		// Install or update the assets if necessary
+		if (!assetsAreUpToDate()) installAssets();
+		LOG.info("Starting Tor");
+		// Watch for the auth cookie file being updated
+		cookieFile.getParentFile().mkdirs();
+		cookieFile.createNewFile();
+		CountDownLatch latch = new CountDownLatch(1);
+		FileObserver obs = new WriteObserver(cookieFile, latch);
+		obs.startWatching();
+		// Start a new Tor process
+		String torPath = torFile.getAbsolutePath();
+		String configPath = configFile.getAbsolutePath();
+		String pid = String.valueOf(android.os.Process.myPid());
+		String[] cmd = {torPath, "-f", configPath, OWNER, pid};
+		String[] env = {"HOME=" + torDirectory.getAbsolutePath()};
+		Process torProcess;
+		try {
+			torProcess = Runtime.getRuntime().exec(cmd, env, torDirectory);
+		} catch (SecurityException e) {
+			throw new IOException(e);
+		}
+		// Log the process's standard output until it detaches
+		if (LOG.isLoggable(INFO)) {
+			Scanner stdout = new Scanner(torProcess.getInputStream());
+			while (stdout.hasNextLine()) LOG.info(stdout.nextLine());
+			stdout.close();
+		}
+		try {
+			// Wait for the process to detach or exit
+			int exit = torProcess.waitFor();
+			if (exit != 0) {
+				if (LOG.isLoggable(WARNING))
+					LOG.warning("Tor exited with value " + exit);
+				return false;
+			}
+			// Wait for the auth cookie file to be created/updated
+			if (!latch.await(COOKIE_TIMEOUT, MILLISECONDS)) {
+				LOG.warning("Auth cookie not created");
+				if (LOG.isLoggable(INFO)) listFiles(torDirectory);
+				return false;
+			}
+		} catch (InterruptedException e) {
+			LOG.warning("Interrupted while starting Tor");
+			Thread.currentThread().interrupt();
+			return false;
+		}
+		// Open a control connection and authenticate using the cookie file
+		controlSocket = new Socket("127.0.0.1", CONTROL_PORT);
+		controlConnection = new TorControlConnection(controlSocket);
+		controlConnection.authenticate(read(cookieFile));
+		// Tell Tor to exit when the control connection is closed
+		controlConnection.takeOwnership();
+		controlConnection.resetConf(Collections.singletonList(OWNER));
+		running = true;
+		// Register to receive events from the Tor process
+		controlConnection.setEventHandler(this);
+		controlConnection.setEvents(Arrays.asList(EVENTS));
+		// Check whether Tor has already bootstrapped
+		String phase = controlConnection.getInfo("status/bootstrap-phase");
+		if (phase != null && phase.contains("PROGRESS=100")) {
+			LOG.info("Tor has already bootstrapped");
+			connectionStatus.setBootstrapped();
+		}
+		// Register to receive network status events
+		networkStateReceiver = new NetworkStateReceiver();
+		IntentFilter filter = new IntentFilter(CONNECTIVITY_ACTION);
+		appContext.registerReceiver(networkStateReceiver, filter);
+		// Bind a server socket to receive incoming hidden service connections
+		bind();
+		return true;
+	}
+
+	private boolean assetsAreUpToDate() {
+		try {
+			PackageManager pm = appContext.getPackageManager();
+			PackageInfo pi = pm.getPackageInfo(appContext.getPackageName(), 0);
+			return doneFile.lastModified() > pi.lastUpdateTime;
+		} catch (NameNotFoundException e) {
+			throw new RuntimeException(e);
+		}
+	}
+
+	private void installAssets() throws IOException {
+		InputStream in = null;
+		OutputStream out = null;
+		try {
+			doneFile.delete();
+			// Unzip the Tor binary to the filesystem
+			in = getTorInputStream();
+			out = new FileOutputStream(torFile);
+			IoUtils.copyAndClose(in, out);
+			// Make the Tor binary executable
+			if (!torFile.setExecutable(true, true)) throw new IOException();
+			// Unzip the GeoIP database to the filesystem
+			in = getGeoIpInputStream();
+			out = new FileOutputStream(geoIpFile);
+			IoUtils.copyAndClose(in, out);
+			// Copy the config file to the filesystem
+			in = getConfigInputStream();
+			out = new FileOutputStream(configFile);
+			IoUtils.copyAndClose(in, out);
+			doneFile.createNewFile();
+		} catch (IOException e) {
+			tryToClose(in);
+			tryToClose(out);
+			throw e;
+		}
+	}
+
+	private InputStream getTorInputStream() throws IOException {
+		if (LOG.isLoggable(INFO))
+			LOG.info("Installing Tor binary for " + architecture);
+		int resId = getResourceId("tor_" + architecture);
+		InputStream in = appContext.getResources().openRawResource(resId);
+		ZipInputStream zin = new ZipInputStream(in);
+		if (zin.getNextEntry() == null) throw new IOException();
+		return zin;
+	}
+
+	private InputStream getGeoIpInputStream() throws IOException {
+		int resId = getResourceId("geoip");
+		InputStream in = appContext.getResources().openRawResource(resId);
+		ZipInputStream zin = new ZipInputStream(in);
+		if (zin.getNextEntry() == null) throw new IOException();
+		return zin;
+	}
+
+	private InputStream getConfigInputStream() throws IOException {
+		int resId = getResourceId("torrc");
+		return appContext.getResources().openRawResource(resId);
+	}
+
+	private int getResourceId(String filename) {
+		Resources res = appContext.getResources();
+		return res.getIdentifier(filename, "raw", appContext.getPackageName());
+	}
+
+	private void tryToClose(@Nullable Closeable c) {
+		try {
+			if (c != null) c.close();
+		} catch (IOException e) {
+			if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
+		}
+	}
+
+	private void tryToClose(@Nullable Socket s) {
+		try {
+			if (s != null) s.close();
+		} catch (IOException e) {
+			if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
+		}
+	}
+
+	private void listFiles(File f) {
+		if (f.isDirectory()) {
+			File[] children = f.listFiles();
+			if (children != null) for (File child : children) listFiles(child);
+		} else {
+			LOG.info(f.getAbsolutePath());
+		}
+	}
+
+	private byte[] read(File f) throws IOException {
+		byte[] b = new byte[(int) f.length()];
+		FileInputStream in = new FileInputStream(f);
+		try {
+			int offset = 0;
+			while (offset < b.length) {
+				int read = in.read(b, offset, b.length - offset);
+				if (read == -1) throw new EOFException();
+				offset += read;
+			}
+			return b;
+		} finally {
+			tryToClose(in);
+		}
+	}
+
+	private void sendDevReports() {
+		ioExecutor.execute(new Runnable() {
+			@Override
+			public void run() {
+				// TODO: Trigger this with a TransportEnabledEvent
+				File reportDir = AndroidUtils.getReportDir(appContext);
+				reporter.sendReports(reportDir);
+			}
+		});
+	}
+
+	private void bind() {
+		ioExecutor.execute(new Runnable() {
+			@Override
+			public void run() {
+				// If there's already a port number stored in config, reuse it
+				String portString = callback.getSettings().get("port");
+				int port;
+				if (StringUtils.isNullOrEmpty(portString)) port = 0;
+				else port = Integer.parseInt(portString);
+				// Bind a server socket to receive connections from Tor
+				ServerSocket ss = null;
+				try {
+					ss = new ServerSocket();
+					ss.bind(new InetSocketAddress("127.0.0.1", port));
+				} catch (IOException e) {
+					if (LOG.isLoggable(WARNING))
+						LOG.log(WARNING, e.toString(), e);
+					tryToClose(ss);
+					return;
+				}
+				if (!running) {
+					tryToClose(ss);
+					return;
+				}
+				socket = ss;
+				// Store the port number
+				final String localPort = String.valueOf(ss.getLocalPort());
+				Settings s = new Settings();
+				s.put("port", localPort);
+				callback.mergeSettings(s);
+				// Create a hidden service if necessary
+				ioExecutor.execute(new Runnable() {
+					@Override
+					public void run() {
+						publishHiddenService(localPort);
+					}
+				});
+				backoff.reset();
+				// Accept incoming hidden service connections from Tor
+				acceptContactConnections(ss);
+			}
+		});
+	}
+
+	private void tryToClose(@Nullable ServerSocket ss) {
+		try {
+			if (ss != null) ss.close();
+		} catch (IOException e) {
+			if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
+		} finally {
+			callback.transportDisabled();
+		}
+	}
+
+	private void publishHiddenService(String port) {
+		if (!running) return;
+		LOG.info("Creating hidden service");
+		String privKey = callback.getSettings().get(HS_PRIVKEY);
+		Map<Integer, String> portLines =
+				Collections.singletonMap(80, "127.0.0.1:" + port);
+		Map<String, String> response;
+		try {
+			// Use the control connection to set up the hidden service
+			if (privKey == null)
+				response = controlConnection.addOnion(portLines);
+			else response = controlConnection.addOnion(privKey, portLines);
+		} catch (IOException e) {
+			if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
+			return;
+		}
+		if (!response.containsKey(HS_ADDRESS)) {
+			LOG.warning("Tor did not return a hidden service address");
+			return;
+		}
+		if (privKey == null && !response.containsKey(HS_PRIVKEY)) {
+			LOG.warning("Tor did not return a private key");
+			return;
+		}
+		// Publish the hidden service's onion hostname in transport properties
+		String hostname = response.get(HS_ADDRESS);
+		if (LOG.isLoggable(INFO))
+			LOG.info("Hidden service " + scrubOnion(hostname));
+		TransportProperties p = new TransportProperties();
+		p.put(PROP_ONION, hostname);
+		callback.mergeLocalProperties(p);
+		if (privKey == null) {
+			// Save the hidden service's private key for next time
+			Settings s = new Settings();
+			s.put(HS_PRIVKEY, response.get(HS_PRIVKEY));
+			callback.mergeSettings(s);
+		}
+	}
+
+	private void acceptContactConnections(ServerSocket ss) {
+		while (running) {
+			Socket s;
+			try {
+				s = ss.accept();
+				s.setSoTimeout(socketTimeout);
+			} catch (IOException e) {
+				// This is expected when the socket is closed
+				if (LOG.isLoggable(INFO)) LOG.info(e.toString());
+				return;
+			}
+			LOG.info("Connection received");
+			backoff.reset();
+			TorTransportConnection conn = new TorTransportConnection(this, s);
+			callback.incomingConnectionCreated(conn);
+		}
+	}
+
+	private void enableNetwork(boolean enable) throws IOException {
+		if (!running) return;
+		if (enable) wakeLock.acquire();
+		connectionStatus.enableNetwork(enable);
+		controlConnection.setConf("DisableNetwork", enable ? "0" : "1");
+		if (!enable) {
+			callback.transportDisabled();
+			wakeLock.release();
+		}
+	}
+
+	@Override
+	public void stop() throws IOException {
+		running = false;
+		tryToClose(socket);
+		if (networkStateReceiver != null)
+			appContext.unregisterReceiver(networkStateReceiver);
+		if (controlSocket != null && controlConnection != null) {
+			try {
+				LOG.info("Stopping Tor");
+				controlConnection.setConf("DisableNetwork", "1");
+				controlConnection.shutdownTor("TERM");
+				controlSocket.close();
+			} catch (IOException e) {
+				if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
+			}
+		}
+		wakeLock.release();
+	}
+
+	@Override
+	public boolean isRunning() {
+		return running && connectionStatus.isConnected();
+	}
+
+	@Override
+	public boolean shouldPoll() {
+		return true;
+	}
+
+	@Override
+	public int getPollingInterval() {
+		return backoff.getPollingInterval();
+	}
+
+	@Override
+	public void poll(Collection<ContactId> connected) {
+		if (!isRunning()) return;
+		backoff.increment();
+		// TODO: Pass properties to connectAndCallBack()
+		for (ContactId c : callback.getRemoteProperties().keySet())
+			if (!connected.contains(c)) connectAndCallBack(c);
+	}
+
+	private void connectAndCallBack(final ContactId c) {
+		ioExecutor.execute(new Runnable() {
+			@Override
+			public void run() {
+				DuplexTransportConnection d = createConnection(c);
+				if (d != null) {
+					backoff.reset();
+					callback.outgoingConnectionCreated(c, d);
+				}
+			}
+		});
+	}
+
+	@Override
+	public DuplexTransportConnection createConnection(ContactId c) {
+		if (!isRunning()) return null;
+		TransportProperties p = callback.getRemoteProperties().get(c);
+		if (p == null) return null;
+		String onion = p.get(PROP_ONION);
+		if (StringUtils.isNullOrEmpty(onion)) return null;
+		if (!ONION.matcher(onion).matches()) {
+			// not scrubbing this address, so we are able to find the problem
+			if (LOG.isLoggable(INFO)) LOG.info("Invalid hostname: " + onion);
+			return null;
+		}
+		Socket s = null;
+		try {
+			if (LOG.isLoggable(INFO))
+				LOG.info("Connecting to " + scrubOnion(onion));
+			controlConnection.forgetHiddenService(onion);
+			s = torSocketFactory.createSocket(onion + ".onion", 80);
+			s.setSoTimeout(socketTimeout);
+			if (LOG.isLoggable(INFO))
+				LOG.info("Connected to " + scrubOnion(onion));
+			return new TorTransportConnection(this, s);
+		} catch (IOException e) {
+			if (LOG.isLoggable(INFO)) {
+				LOG.info("Could not connect to " + scrubOnion(onion) + ": " +
+						e.toString());
+			}
+			tryToClose(s);
+			return null;
+		}
+	}
+
+	@Override
+	public boolean supportsInvitations() {
+		return false;
+	}
+
+	@Override
+	public DuplexTransportConnection createInvitationConnection(PseudoRandom r,
+			long timeout, boolean alice) {
+		throw new UnsupportedOperationException();
+	}
+
+	@Override
+	public boolean supportsKeyAgreement() {
+		return false;
+	}
+
+	@Override
+	public KeyAgreementListener createKeyAgreementListener(byte[] commitment) {
+		throw new UnsupportedOperationException();
+	}
+
+	@Override
+	public DuplexTransportConnection createKeyAgreementConnection(
+			byte[] commitment, BdfList descriptor, long timeout) {
+		throw new UnsupportedOperationException();
+	}
+
+	@Override
+	public void circuitStatus(String status, String id, String path) {
+		if (status.equals("BUILT") &&
+				connectionStatus.getAndSetCircuitBuilt()) {
+			LOG.info("First circuit built");
+			backoff.reset();
+			if (isRunning()) {
+				sendDevReports();
+				callback.transportEnabled();
+			}
+		}
+	}
+
+	@Override
+	public void streamStatus(String status, String id, String target) {
+	}
+
+	@Override
+	public void orConnStatus(String status, String orName) {
+		if (LOG.isLoggable(INFO)) LOG.info("OR connection " + status);
+	}
+
+	@Override
+	public void bandwidthUsed(long read, long written) {
+	}
+
+	@Override
+	public void newDescriptors(List<String> orList) {
+	}
+
+	@Override
+	public void message(String severity, String msg) {
+		if (LOG.isLoggable(INFO)) LOG.info(severity + " " + msg);
+		if (severity.equals("NOTICE") && msg.startsWith("Bootstrapped 100%")) {
+			connectionStatus.setBootstrapped();
+			backoff.reset();
+			if (isRunning()) {
+				sendDevReports();
+				callback.transportEnabled();
+			}
+		}
+	}
+
+	@Override
+	public void unrecognized(String type, String msg) {
+		if (type.equals("HS_DESC") && msg.startsWith("UPLOADED"))
+			LOG.info("Descriptor uploaded");
+	}
+
+	private static class WriteObserver extends FileObserver {
+
+		private final CountDownLatch latch;
+
+		private WriteObserver(File file, CountDownLatch latch) {
+			super(file.getAbsolutePath(), CLOSE_WRITE);
+			this.latch = latch;
+		}
+
+		@Override
+		public void onEvent(int event, String path) {
+			stopWatching();
+			latch.countDown();
+		}
+	}
+
+	@Override
+	public void eventOccurred(Event e) {
+		if (e instanceof SettingsUpdatedEvent) {
+			if (((SettingsUpdatedEvent) e).getNamespace().equals("tor")) {
+				LOG.info("Tor settings updated");
+				updateConnectionStatus();
+			}
+		}
+	}
+
+	private void updateConnectionStatus() {
+		ioExecutor.execute(new Runnable() {
+			@Override
+			public void run() {
+				if (!running) return;
+
+				Object o = appContext.getSystemService(CONNECTIVITY_SERVICE);
+				ConnectivityManager cm = (ConnectivityManager) o;
+				NetworkInfo net = cm.getActiveNetworkInfo();
+				boolean online = net != null && net.isConnected();
+				boolean wifi = online && net.getType() == TYPE_WIFI;
+				String country = locationUtils.getCurrentCountry();
+				boolean blocked = TorNetworkMetadata.isTorProbablyBlocked(
+						country);
+				Settings s = callback.getSettings();
+				boolean useMobileData = s.getBoolean("torOverMobile", true);
+
+				if (LOG.isLoggable(INFO)) {
+					LOG.info("Online: " + online + ", wifi: " + wifi);
+					if ("".equals(country)) LOG.info("Country code unknown");
+					else LOG.info("Country code: " + country);
+				}
+
+				try {
+					if (!online) {
+						LOG.info("Disabling network, device is offline");
+						enableNetwork(false);
+					} else if (blocked) {
+						LOG.info("Disabling network, country is blocked");
+						enableNetwork(false);
+					} else if (!wifi && !useMobileData) {
+						LOG.info("Disabling network due to data setting");
+						enableNetwork(false);
+					} else {
+						LOG.info("Enabling network");
+						enableNetwork(true);
+					}
+				} catch (IOException e) {
+					if (LOG.isLoggable(WARNING))
+						LOG.log(WARNING, e.toString(), e);
+				}
+			}
+		});
+	}
+
+	private class NetworkStateReceiver extends BroadcastReceiver {
+
+		@Override
+		public void onReceive(Context ctx, Intent i) {
+			if (!running) return;
+			if (CONNECTIVITY_ACTION.equals(i.getAction())) {
+				LOG.info("Detected connectivity change");
+				updateConnectionStatus();
+			}
+		}
+	}
+
+	private static class ConnectionStatus {
+
+		// All of the following are locking: this
+		private boolean networkEnabled = false;
+		private boolean bootstrapped = false, circuitBuilt = false;
+
+		private synchronized void setBootstrapped() {
+			bootstrapped = true;
+		}
+
+		private synchronized boolean getAndSetCircuitBuilt() {
+			boolean firstCircuit = !circuitBuilt;
+			circuitBuilt = true;
+			return firstCircuit;
+		}
+
+		private synchronized void enableNetwork(boolean enable) {
+			networkEnabled = enable;
+			circuitBuilt = false;
+		}
+
+		private synchronized boolean isConnected() {
+			return networkEnabled && bootstrapped && circuitBuilt;
+		}
+	}
+}

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

@@ -0,0 +1,98 @@
+package org.briarproject.bramble.plugin.tor;
+
+import android.content.Context;
+import android.os.Build;
+
+import org.briarproject.bramble.api.event.EventBus;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.plugin.Backoff;
+import org.briarproject.bramble.api.plugin.BackoffFactory;
+import org.briarproject.bramble.api.plugin.TorConstants;
+import org.briarproject.bramble.api.plugin.TransportId;
+import org.briarproject.bramble.api.plugin.duplex.DuplexPlugin;
+import org.briarproject.bramble.api.plugin.duplex.DuplexPluginCallback;
+import org.briarproject.bramble.api.plugin.duplex.DuplexPluginFactory;
+import org.briarproject.bramble.api.reporting.DevReporter;
+import org.briarproject.bramble.api.system.LocationUtils;
+import org.briarproject.bramble.util.AndroidUtils;
+
+import java.util.concurrent.Executor;
+import java.util.logging.Logger;
+
+import javax.annotation.concurrent.Immutable;
+import javax.net.SocketFactory;
+
+@Immutable
+@NotNullByDefault
+public class TorPluginFactory implements DuplexPluginFactory {
+
+	private static final Logger LOG =
+			Logger.getLogger(TorPluginFactory.class.getName());
+
+	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 Context appContext;
+	private final LocationUtils locationUtils;
+	private final DevReporter reporter;
+	private final EventBus eventBus;
+	private final SocketFactory torSocketFactory;
+	private final BackoffFactory backoffFactory;
+
+	public TorPluginFactory(Executor ioExecutor, Context appContext,
+			LocationUtils locationUtils, DevReporter reporter,
+			EventBus eventBus, SocketFactory torSocketFactory,
+			BackoffFactory backoffFactory) {
+		this.ioExecutor = ioExecutor;
+		this.appContext = appContext;
+		this.locationUtils = locationUtils;
+		this.reporter = reporter;
+		this.eventBus = eventBus;
+		this.torSocketFactory = torSocketFactory;
+		this.backoffFactory = backoffFactory;
+	}
+
+	@Override
+	public TransportId getId() {
+		return TorConstants.ID;
+	}
+
+	@Override
+	public int getMaxLatency() {
+		return MAX_LATENCY;
+	}
+
+	@Override
+	public DuplexPlugin createPlugin(DuplexPluginCallback callback) {
+
+		// Check that we have a Tor binary for this architecture
+		String architecture = null;
+		for (String abi : AndroidUtils.getSupportedArchitectures()) {
+			if (abi.startsWith("x86")) {
+				architecture = "x86";
+				break;
+			} else if (abi.startsWith("armeabi")) {
+				architecture = "arm";
+				break;
+			}
+		}
+		if (architecture == null) {
+			LOG.info("Tor is not supported on this architecture");
+			return null;
+		}
+		// Use position-independent executable for SDK >= 16
+		if (Build.VERSION.SDK_INT >= 16) architecture += "_pie";
+
+		Backoff backoff = backoffFactory.createBackoff(MIN_POLLING_INTERVAL,
+				MAX_POLLING_INTERVAL, BACKOFF_BASE);
+		TorPlugin plugin = new TorPlugin(ioExecutor, appContext, locationUtils,
+				reporter, torSocketFactory, backoff, callback, architecture,
+				MAX_LATENCY, MAX_IDLE_TIME);
+		eventBus.addListener(plugin);
+		return plugin;
+	}
+}

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

@@ -0,0 +1,36 @@
+package org.briarproject.bramble.plugin.tor;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.plugin.Plugin;
+import org.briarproject.bramble.api.plugin.duplex.AbstractDuplexTransportConnection;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.net.Socket;
+
+@NotNullByDefault
+class TorTransportConnection extends AbstractDuplexTransportConnection {
+
+	private final Socket socket;
+
+	TorTransportConnection(Plugin plugin, Socket socket) {
+		super(plugin);
+		this.socket = socket;
+	}
+
+	@Override
+	protected InputStream getInputStream() throws IOException {
+		return socket.getInputStream();
+	}
+
+	@Override
+	protected OutputStream getOutputStream() throws IOException {
+		return socket.getOutputStream();
+	}
+
+	@Override
+	protected void closeConnection(boolean exception) throws IOException {
+		socket.close();
+	}
+}

bramble-android/src/main/java/org/briarproject/bramble/system/AndroidExecutorImpl.java

@@ -0,0 +1,78 @@
+package org.briarproject.bramble.system;
+
+import android.app.Application;
+import android.os.Handler;
+import android.os.Looper;
+
+import org.briarproject.bramble.api.system.AndroidExecutor;
+
+import java.util.concurrent.Callable;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.Future;
+import java.util.concurrent.FutureTask;
+import java.util.concurrent.RejectedExecutionException;
+import java.util.concurrent.atomic.AtomicBoolean;
+
+import javax.inject.Inject;
+
+class AndroidExecutorImpl implements AndroidExecutor {
+
+	private final Handler uiHandler;
+	private final Runnable loop;
+	private final AtomicBoolean started = new AtomicBoolean(false);
+	private final CountDownLatch startLatch = new CountDownLatch(1);
+
+	private volatile Handler backgroundHandler = null;
+
+	@Inject
+	AndroidExecutorImpl(Application app) {
+		uiHandler = new Handler(app.getApplicationContext().getMainLooper());
+		loop = new Runnable() {
+			@Override
+			public void run() {
+				Looper.prepare();
+				backgroundHandler = new Handler();
+				startLatch.countDown();
+				Looper.loop();
+			}
+		};
+	}
+
+	private void startIfNecessary() {
+		if (!started.getAndSet(true)) {
+			Thread t = new Thread(loop, "AndroidExecutor");
+			t.setDaemon(true);
+			t.start();
+		}
+		try {
+			startLatch.await();
+		} catch (InterruptedException e) {
+			throw new RejectedExecutionException(e);
+		}
+	}
+
+	@Override
+	public <V> Future<V> runOnBackgroundThread(Callable<V> c) {
+		FutureTask<V> f = new FutureTask<>(c);
+		runOnBackgroundThread(f);
+		return f;
+	}
+
+	@Override
+	public void runOnBackgroundThread(Runnable r) {
+		startIfNecessary();
+		backgroundHandler.post(r);
+	}
+
+	@Override
+	public <V> Future<V> runOnUiThread(Callable<V> c) {
+		FutureTask<V> f = new FutureTask<>(c);
+		runOnUiThread(f);
+		return f;
+	}
+
+	@Override
+	public void runOnUiThread(Runnable r) {
+		uiHandler.post(r);
+	}
+}

bramble-android/src/main/java/org/briarproject/bramble/system/AndroidLocationUtils.java

@@ -0,0 +1,72 @@
+package org.briarproject.bramble.system;
+
+import android.annotation.SuppressLint;
+import android.app.Application;
+import android.content.Context;
+import android.telephony.TelephonyManager;
+import android.text.TextUtils;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.system.LocationUtils;
+
+import java.util.Locale;
+import java.util.logging.Logger;
+
+import javax.inject.Inject;
+
+import static android.content.Context.TELEPHONY_SERVICE;
+
+@NotNullByDefault
+class AndroidLocationUtils implements LocationUtils {
+
+	private static final Logger LOG =
+			Logger.getLogger(AndroidLocationUtils.class.getName());
+
+	private final Context appContext;
+
+	@Inject
+	AndroidLocationUtils(Application app) {
+		appContext = app.getApplicationContext();
+	}
+
+	/**
+	 * This guesses the current country from the first of these sources that
+	 * succeeds (also in order of likelihood of being correct):
+	 *
+	 * <ul>
+	 * <li>Phone network. This works even when no SIM card is inserted, or a
+	 *     foreign SIM card is inserted.</li>
+	 * <li>SIM card. This is only an heuristic and assumes the user is not
+	 *     roaming.</li>
+	 * <li>User locale. This is an even worse heuristic.</li>
+	 * </ul>
+	 *
+	 * Note: this is very similar to <a href="https://android.googlesource.com/platform/frameworks/base/+/cd92588%5E/location/java/android/location/CountryDetector.java">
+	 * this API</a> except it seems that Google doesn't want us to use it for
+	 * some reason - both that class and {@code Context.COUNTRY_CODE} are
+	 * annotated {@code @hide}.
+	 */
+	@Override
+	@SuppressLint("DefaultLocale")
+	public String getCurrentCountry() {
+		String countryCode = getCountryFromPhoneNetwork();
+		if (!TextUtils.isEmpty(countryCode)) return countryCode.toUpperCase();
+		LOG.info("Falling back to SIM card country");
+		countryCode = getCountryFromSimCard();
+		if (!TextUtils.isEmpty(countryCode)) return countryCode.toUpperCase();
+		LOG.info("Falling back to user-defined locale");
+		return Locale.getDefault().getCountry();
+	}
+
+	private String getCountryFromPhoneNetwork() {
+		Object o = appContext.getSystemService(TELEPHONY_SERVICE);
+		TelephonyManager tm = (TelephonyManager) o;
+		return tm.getNetworkCountryIso();
+	}
+
+	private String getCountryFromSimCard() {
+		Object o = appContext.getSystemService(TELEPHONY_SERVICE);
+		TelephonyManager tm = (TelephonyManager) o;
+		return tm.getSimCountryIso();
+	}
+}

bramble-android/src/main/java/org/briarproject/bramble/system/AndroidSeedProvider.java

@@ -0,0 +1,42 @@
+package org.briarproject.bramble.system;
+
+import android.app.Application;
+import android.content.ContentResolver;
+import android.content.Context;
+import android.os.Build;
+import android.provider.Settings;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import java.io.DataOutputStream;
+import java.io.IOException;
+
+import javax.annotation.concurrent.Immutable;
+import javax.inject.Inject;
+
+import static android.provider.Settings.Secure.ANDROID_ID;
+
+@Immutable
+@NotNullByDefault
+class AndroidSeedProvider extends LinuxSeedProvider {
+
+	private final Context appContext;
+
+	@Inject
+	AndroidSeedProvider(Application app) {
+		appContext = app.getApplicationContext();
+	}
+
+	@Override
+	void writeToEntropyPool(DataOutputStream out) throws IOException {
+		out.writeInt(android.os.Process.myPid());
+		out.writeInt(android.os.Process.myTid());
+		out.writeInt(android.os.Process.myUid());
+		if (Build.FINGERPRINT != null) out.writeUTF(Build.FINGERPRINT);
+		if (Build.SERIAL != null) out.writeUTF(Build.SERIAL);
+		ContentResolver contentResolver = appContext.getContentResolver();
+		String id = Settings.Secure.getString(contentResolver, ANDROID_ID);
+		if (id != null) out.writeUTF(id);
+		super.writeToEntropyPool(out);
+	}
+}

bramble-android/src/main/java/org/briarproject/bramble/system/AndroidSystemModule.java

@@ -0,0 +1,33 @@
+package org.briarproject.bramble.system;
+
+import android.app.Application;
+
+import org.briarproject.bramble.api.system.AndroidExecutor;
+import org.briarproject.bramble.api.system.LocationUtils;
+import org.briarproject.bramble.api.system.SeedProvider;
+
+import javax.inject.Singleton;
+
+import dagger.Module;
+import dagger.Provides;
+
+@Module
+public class AndroidSystemModule {
+
+	@Provides
+	@Singleton
+	SeedProvider provideSeedProvider(Application app) {
+		return new AndroidSeedProvider(app);
+	}
+
+	@Provides
+	LocationUtils provideLocationUtils(Application app) {
+		return new AndroidLocationUtils(app);
+	}
+
+	@Provides
+	@Singleton
+	AndroidExecutor provideAndroidExecutor(Application app) {
+		return new AndroidExecutorImpl(app);
+	}
+}

bramble-android/src/main/java/org/briarproject/bramble/util/AndroidUtils.java

@@ -0,0 +1,70 @@
+package org.briarproject.bramble.util;
+
+import android.bluetooth.BluetoothAdapter;
+import android.content.Context;
+import android.os.Build;
+import android.provider.Settings;
+
+import java.io.File;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.List;
+
+import static android.content.Context.MODE_PRIVATE;
+
+public class AndroidUtils {
+
+	// Fake Bluetooth address returned by BluetoothAdapter on API 23 and later
+	private static final String FAKE_BLUETOOTH_ADDRESS = "02:00:00:00:00:00";
+
+	private static final String STORED_REPORTS = "dev-reports";
+
+	@SuppressWarnings("deprecation")
+	public static Collection<String> getSupportedArchitectures() {
+		List<String> abis = new ArrayList<>();
+		if (Build.VERSION.SDK_INT >= 21) {
+			abis.addAll(Arrays.asList(Build.SUPPORTED_ABIS));
+		} else {
+			abis.add(Build.CPU_ABI);
+			if (Build.CPU_ABI2 != null) abis.add(Build.CPU_ABI2);
+		}
+		return abis;
+	}
+
+	public static String getBluetoothAddress(Context ctx,
+			BluetoothAdapter adapter) {
+		// Return the adapter's address if it's valid and not fake
+		String address = adapter.getAddress();
+		if (isValidBluetoothAddress(address)) return address;
+		// Return the address from settings if it's valid and not fake
+		address = Settings.Secure.getString(ctx.getContentResolver(),
+				"bluetooth_address");
+		if (isValidBluetoothAddress(address)) return address;
+		// Let the caller know we can't find the address
+		return "";
+	}
+
+	private static boolean isValidBluetoothAddress(String address) {
+		return !StringUtils.isNullOrEmpty(address)
+				&& BluetoothAdapter.checkBluetoothAddress(address)
+				&& !address.equals(FAKE_BLUETOOTH_ADDRESS);
+	}
+
+	public static void deleteAppData(Context ctx) {
+		File dataDir = new File(ctx.getApplicationInfo().dataDir);
+		File[] children = dataDir.listFiles();
+		if (children != null) {
+			for (File child : children) {
+				if (!child.getName().equals("lib"))
+					IoUtils.deleteFileOrDir(child);
+			}
+		}
+		// Recreate the cache dir as some OpenGL drivers expect it to exist
+		new File(dataDir, "cache").mkdir();
+	}
+
+	public static File getReportDir(Context ctx) {
+		return ctx.getDir(STORED_REPORTS, MODE_PRIVATE);
+	}
+}