Merge branch '581-plugin-states' into 'plugin-toggles'

Better methods for querying plugin states

See merge request briar/briar!1209

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

@@ -8,6 +8,7 @@ import org.briarproject.bramble.api.lifecycle.ServiceException;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.ConnectionManager;
 import org.briarproject.bramble.api.plugin.Plugin;
+import org.briarproject.bramble.api.plugin.Plugin.State;
 import org.briarproject.bramble.api.plugin.PluginCallback;
 import org.briarproject.bramble.api.plugin.PluginConfig;
 import org.briarproject.bramble.api.plugin.PluginException;
@@ -18,8 +19,9 @@ import org.briarproject.bramble.api.plugin.TransportId;
 import org.briarproject.bramble.api.plugin.duplex.DuplexPlugin;
 import org.briarproject.bramble.api.plugin.duplex.DuplexPluginFactory;
 import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
-import org.briarproject.bramble.api.plugin.event.TransportDisabledEvent;
-import org.briarproject.bramble.api.plugin.event.TransportEnabledEvent;
+import org.briarproject.bramble.api.plugin.event.TransportActiveEvent;
+import org.briarproject.bramble.api.plugin.event.TransportInactiveEvent;
+import org.briarproject.bramble.api.plugin.event.TransportStateEvent;
 import org.briarproject.bramble.api.plugin.simplex.SimplexPlugin;
 import org.briarproject.bramble.api.plugin.simplex.SimplexPluginFactory;
 import org.briarproject.bramble.api.properties.TransportProperties;
@@ -36,6 +38,7 @@ import java.util.concurrent.CopyOnWriteArrayList;
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.Executor;
 import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.concurrent.atomic.AtomicReference;
 import java.util.logging.Logger;
 
 import javax.annotation.concurrent.ThreadSafe;
@@ -45,6 +48,8 @@ import static java.util.logging.Level.FINE;
 import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
 import static java.util.logging.Logger.getLogger;
+import static org.briarproject.bramble.api.plugin.Plugin.State.ACTIVE;
+import static org.briarproject.bramble.api.plugin.Plugin.State.DISABLED;
 import static org.briarproject.bramble.util.LogUtils.logDuration;
 import static org.briarproject.bramble.util.LogUtils.logException;
 import static org.briarproject.bramble.util.LogUtils.now;
@@ -250,7 +255,8 @@ class PluginManagerImpl implements PluginManager, Service {
 	private class Callback implements PluginCallback {
 
 		private final TransportId id;
-		private final AtomicBoolean enabled = new AtomicBoolean(false);
+		private final AtomicReference<State> state =
+				new AtomicReference<>(DISABLED);
 
 		private Callback(TransportId id) {
 			this.id = id;
@@ -295,15 +301,20 @@ class PluginManagerImpl implements PluginManager, Service {
 		}
 
 		@Override
-		public void transportEnabled() {
-			if (!enabled.getAndSet(true))
-				eventBus.broadcast(new TransportEnabledEvent(id));
-		}
-
-		@Override
-		public void transportDisabled() {
-			if (enabled.getAndSet(false))
-				eventBus.broadcast(new TransportDisabledEvent(id));
+		public void pluginStateChanged(State newState) {
+			State oldState = state.getAndSet(newState);
+			if (newState != oldState) {
+				if (LOG.isLoggable(INFO)) {
+					LOG.info(id + " changed from state " + oldState
+							+ " to " + newState);
+				}
+				eventBus.broadcast(new TransportStateEvent(id, newState));
+				if (newState == ACTIVE) {
+					eventBus.broadcast(new TransportActiveEvent(id));
+				} else if (oldState == ACTIVE) {
+					eventBus.broadcast(new TransportInactiveEvent(id));
+				}
+			}
 		}
 
 		@Override

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

@@ -20,8 +20,8 @@ import org.briarproject.bramble.api.plugin.duplex.DuplexPlugin;
 import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
 import org.briarproject.bramble.api.plugin.event.ConnectionClosedEvent;
 import org.briarproject.bramble.api.plugin.event.ConnectionOpenedEvent;
-import org.briarproject.bramble.api.plugin.event.TransportDisabledEvent;
-import org.briarproject.bramble.api.plugin.event.TransportEnabledEvent;
+import org.briarproject.bramble.api.plugin.event.TransportActiveEvent;
+import org.briarproject.bramble.api.plugin.event.TransportInactiveEvent;
 import org.briarproject.bramble.api.plugin.simplex.SimplexPlugin;
 import org.briarproject.bramble.api.properties.TransportProperties;
 import org.briarproject.bramble.api.properties.TransportPropertyManager;
@@ -106,13 +106,13 @@ class PollerImpl implements Poller, EventListener {
 			ConnectionOpenedEvent c = (ConnectionOpenedEvent) e;
 			// Reschedule polling, the polling interval may have decreased
 			reschedule(c.getTransportId());
-		} else if (e instanceof TransportEnabledEvent) {
-			TransportEnabledEvent t = (TransportEnabledEvent) e;
-			// Poll the newly enabled transport
+		} else if (e instanceof TransportActiveEvent) {
+			TransportActiveEvent t = (TransportActiveEvent) e;
+			// Poll the newly activated transport
 			pollNow(t.getTransportId());
-		} else if (e instanceof TransportDisabledEvent) {
-			TransportDisabledEvent t = (TransportDisabledEvent) e;
-			// Cancel polling for the disabled transport
+		} else if (e instanceof TransportInactiveEvent) {
+			TransportInactiveEvent t = (TransportInactiveEvent) e;
+			// Cancel polling for the deactivated transport
 			cancel(t.getTransportId());
 		}
 	}

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

@@ -10,6 +10,7 @@ import org.briarproject.bramble.api.keyagreement.KeyAgreementListener;
 import org.briarproject.bramble.api.keyagreement.event.KeyAgreementListeningEvent;
 import org.briarproject.bramble.api.keyagreement.event.KeyAgreementStoppedListeningEvent;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.bramble.api.plugin.Backoff;
 import org.briarproject.bramble.api.plugin.ConnectionHandler;
@@ -36,6 +37,8 @@ import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.logging.Logger;
 
 import javax.annotation.Nullable;
+import javax.annotation.concurrent.GuardedBy;
+import javax.annotation.concurrent.ThreadSafe;
 
 import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
@@ -46,6 +49,9 @@ import static org.briarproject.bramble.api.plugin.BluetoothConstants.PREF_BT_ENA
 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.api.plugin.Plugin.State.ACTIVE;
+import static org.briarproject.bramble.api.plugin.Plugin.State.DISABLED;
+import static org.briarproject.bramble.api.plugin.Plugin.State.INACTIVE;
 import static org.briarproject.bramble.util.LogUtils.logException;
 import static org.briarproject.bramble.util.PrivacyUtils.scrubMacAddress;
 import static org.briarproject.bramble.util.StringUtils.isNullOrEmpty;
@@ -68,9 +74,10 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 	private final int maxLatency;
 	private final AtomicBoolean used = new AtomicBoolean(false);
 
-	private volatile boolean running = false, contactConnections = false;
+	protected final PluginState state = new PluginState();
+
+	private volatile boolean contactConnections = false;
 	private volatile String contactConnectionsUuid = null;
-	private volatile SS socket = null;
 
 	abstract void initialiseAdapter() throws IOException;
 
@@ -120,13 +127,15 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 		// We may not have been able to get the local address before
 		ioExecutor.execute(this::updateProperties);
 		if (shouldAllowContactConnections()) bind();
+		callback.pluginStateChanged(getState());
 	}
 
 	void onAdapterDisabled() {
 		LOG.info("Bluetooth disabled");
-		tryToClose(socket);
 		connectionLimiter.allConnectionsClosed();
-		callback.transportDisabled();
+		// The server socket may not have been closed automatically
+		tryToClose(state.clearServerSocket());
+		callback.pluginStateChanged(getState());
 	}
 
 	@Override
@@ -154,7 +163,7 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 			throw new PluginException(e);
 		}
 		updateProperties();
-		running = true;
+		state.setStarted();
 		loadSettings(callback.getSettings());
 		if (shouldAllowContactConnections()) {
 			if (isAdapterEnabled()) bind();
@@ -172,7 +181,8 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 
 	private void bind() {
 		ioExecutor.execute(() -> {
-			if (!isRunning() || !shouldAllowContactConnections()) return;
+			if (!shouldAllowContactConnections() || getState() != ACTIVE)
+				return;
 			// Bind a server socket to accept connections from contacts
 			SS ss;
 			try {
@@ -181,14 +191,14 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 				logException(LOG, WARNING, e);
 				return;
 			}
-			if (!isRunning() || !shouldAllowContactConnections()) {
+			if (!shouldAllowContactConnections() ||
+					!state.setServerSocket(ss)) {
+				LOG.info("Closing redundant server socket");
 				tryToClose(ss);
 				return;
 			}
-			socket = ss;
 			backoff.reset();
-			callback.transportEnabled();
-			acceptContactConnections();
+			acceptContactConnections(ss);
 		});
 	}
 
@@ -217,34 +227,39 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 		if (changed) callback.mergeLocalProperties(p);
 	}
 
-	private void acceptContactConnections() {
+	private void acceptContactConnections(SS ss) {
 		while (true) {
 			DuplexTransportConnection conn;
 			try {
-				conn = acceptConnection(socket);
+				conn = acceptConnection(ss);
 			} catch (IOException e) {
-				// This is expected when the socket is closed
-				if (LOG.isLoggable(INFO)) LOG.info(e.toString());
+				// This is expected when the server socket is closed
+				LOG.info("Server socket closed");
+				state.clearServerSocket();
 				return;
 			}
+			LOG.info("Connection received");
 			backoff.reset();
 			if (connectionLimiter.contactConnectionOpened(conn))
 				callback.handleConnection(conn);
-			if (!running) return;
 		}
 	}
 
 	@Override
 	public void stop() {
-		running = false;
-		tryToClose(socket);
-		callback.transportDisabled();
+		SS ss = state.setStopped();
+		tryToClose(ss);
 		disableAdapterIfEnabledByUs();
 	}
 
 	@Override
-	public boolean isRunning() {
-		return running && isAdapterEnabled();
+	public State getState() {
+		return state.getState();
+	}
+
+	@Override
+	public int getReasonDisabled() {
+		return getState() == DISABLED ? REASON_STARTING_STOPPING : -1;
 	}
 
 	@Override
@@ -260,7 +275,7 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 	@Override
 	public void poll(Collection<Pair<TransportProperties, ConnectionHandler>>
 			properties) {
-		if (!isRunning() || !shouldAllowContactConnections()) return;
+		if (!shouldAllowContactConnections() || getState() != ACTIVE) return;
 		backoff.increment();
 		for (Pair<TransportProperties, ConnectionHandler> p : properties) {
 			connect(p.getFirst(), p.getSecond());
@@ -273,7 +288,8 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 		String uuid = p.get(PROP_UUID);
 		if (isNullOrEmpty(uuid)) return;
 		ioExecutor.execute(() -> {
-			if (!isRunning() || !shouldAllowContactConnections()) return;
+			if (!shouldAllowContactConnections() || getState() != ACTIVE)
+				return;
 			if (!connectionLimiter.canOpenContactConnection()) return;
 			DuplexTransportConnection d = createConnection(p);
 			if (d != null) {
@@ -317,7 +333,8 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 
 	@Override
 	public DuplexTransportConnection createConnection(TransportProperties p) {
-		if (!isRunning() || !shouldAllowContactConnections()) return null;
+		if (!shouldAllowContactConnections() || getState() != ACTIVE)
+			return null;
 		if (!connectionLimiter.canOpenContactConnection()) return null;
 		String address = p.get(PROP_ADDRESS);
 		if (isNullOrEmpty(address)) return null;
@@ -336,7 +353,7 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 
 	@Override
 	public KeyAgreementListener createKeyAgreementListener(byte[] commitment) {
-		if (!isRunning()) return null;
+		if (getState() != ACTIVE) return null;
 		// No truncation necessary because COMMIT_LENGTH = 16
 		String uuid = UUID.nameUUIDFromBytes(commitment).toString();
 		if (LOG.isLoggable(INFO)) LOG.info("Key agreement UUID " + uuid);
@@ -348,7 +365,7 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 			logException(LOG, WARNING, e);
 			return null;
 		}
-		if (!isRunning()) {
+		if (getState() != ACTIVE) {
 			tryToClose(ss);
 			return null;
 		}
@@ -362,7 +379,7 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 	@Override
 	public DuplexTransportConnection createKeyAgreementConnection(
 			byte[] commitment, BdfList descriptor) {
-		if (!isRunning()) return null;
+		if (getState() != ACTIVE) return null;
 		// No truncation necessary because COMMIT_LENGTH = 16
 		String uuid = UUID.nameUUIDFromBytes(commitment).toString();
 		DuplexTransportConnection conn;
@@ -428,8 +445,7 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 		boolean isAllowed = shouldAllowContactConnections();
 		if (wasAllowed && !isAllowed) {
 			LOG.info("Contact connections disabled");
-			tryToClose(socket);
-			callback.transportDisabled();
+			tryToClose(state.clearServerSocket());
 			disableAdapterIfEnabledByUs();
 		} else if (!wasAllowed && isAllowed) {
 			LOG.info("Contact connections enabled");
@@ -460,4 +476,48 @@ abstract class BluetoothPlugin<SS> implements DuplexPlugin, EventListener {
 			tryToClose(ss);
 		}
 	}
+
+	@ThreadSafe
+	@NotNullByDefault
+	protected class PluginState {
+
+		@GuardedBy("this")
+		private boolean started = false, stopped = false;
+		@GuardedBy("this")
+		@Nullable
+		private SS serverSocket = null;
+
+		synchronized void setStarted() {
+			started = true;
+			callback.pluginStateChanged(getState());
+		}
+
+		@Nullable
+		synchronized SS setStopped() {
+			stopped = true;
+			SS ss = serverSocket;
+			serverSocket = null;
+			callback.pluginStateChanged(getState());
+			return ss;
+		}
+
+		synchronized boolean setServerSocket(SS ss) {
+			if (stopped || serverSocket != null) return false;
+			serverSocket = ss;
+			callback.pluginStateChanged(getState());
+			return true;
+		}
+
+		@Nullable
+		synchronized SS clearServerSocket() {
+			SS ss = serverSocket;
+			serverSocket = null;
+			return ss;
+		}
+
+		synchronized State getState() {
+			if (!started || stopped) return DISABLED;
+			return isAdapterEnabled() ? ACTIVE : INACTIVE;
+		}
+	}
 }

bramble-core/src/main/java/org/briarproject/bramble/plugin/file/FilePlugin.java

@@ -16,6 +16,7 @@ import java.util.logging.Logger;
 import static java.util.logging.Level.WARNING;
 import static java.util.logging.Logger.getLogger;
 import static org.briarproject.bramble.api.plugin.FileConstants.PROP_PATH;
+import static org.briarproject.bramble.api.plugin.Plugin.State.ACTIVE;
 import static org.briarproject.bramble.util.LogUtils.logException;
 import static org.briarproject.bramble.util.StringUtils.isNullOrEmpty;
 
@@ -45,7 +46,7 @@ abstract class FilePlugin implements SimplexPlugin {
 
 	@Override
 	public TransportConnectionReader createReader(TransportProperties p) {
-		if (!isRunning()) return null;
+		if (getState() != ACTIVE) return null;
 		String path = p.get(PROP_PATH);
 		if (isNullOrEmpty(path)) return null;
 		try {
@@ -60,7 +61,7 @@ abstract class FilePlugin implements SimplexPlugin {
 
 	@Override
 	public TransportConnectionWriter createWriter(TransportProperties p) {
-		if (!isRunning()) return null;
+		if (getState() != ACTIVE) return null;
 		String path = p.get(PROP_PATH);
 		if (isNullOrEmpty(path)) return null;
 		try {

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

@@ -11,7 +11,6 @@ import org.briarproject.bramble.api.plugin.TransportId;
 import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
 import org.briarproject.bramble.api.properties.TransportProperties;
 import org.briarproject.bramble.api.settings.Settings;
-import org.briarproject.bramble.util.IoUtils;
 
 import java.io.IOException;
 import java.net.Inet4Address;
@@ -19,7 +18,6 @@ import java.net.InetAddress;
 import java.net.InetSocketAddress;
 import java.net.ServerSocket;
 import java.net.Socket;
-import java.net.SocketAddress;
 import java.net.UnknownHostException;
 import java.util.ArrayList;
 import java.util.Comparator;
@@ -38,6 +36,7 @@ import static org.briarproject.bramble.api.plugin.LanTcpConstants.ID;
 import static org.briarproject.bramble.api.plugin.LanTcpConstants.PREF_LAN_IP_PORTS;
 import static org.briarproject.bramble.api.plugin.LanTcpConstants.PROP_IP_PORTS;
 import static org.briarproject.bramble.util.ByteUtils.MAX_16_BIT_UNSIGNED;
+import static org.briarproject.bramble.util.IoUtils.tryToClose;
 import static org.briarproject.bramble.util.PrivacyUtils.scrubSocketAddress;
 import static org.briarproject.bramble.util.StringUtils.isNullOrEmpty;
 import static org.briarproject.bramble.util.StringUtils.join;
@@ -149,8 +148,9 @@ class LanTcpPlugin extends TcpPlugin {
 		if (remote.getPort() == 0) return false;
 		if (!isAcceptableAddress(remote.getAddress())) return false;
 		// Try to determine whether the address is on the same LAN as us
-		if (socket == null) return false;
-		byte[] localIp = socket.getInetAddress().getAddress();
+		ServerSocket ss = state.getServerSocket();
+		if (ss == null) return false;
+		byte[] localIp = ss.getInetAddress().getAddress();
 		byte[] remoteIp = remote.getAddress().getAddress();
 		return addressesAreOnSameLan(localIp, remoteIp);
 	}
@@ -209,10 +209,10 @@ class LanTcpPlugin extends TcpPlugin {
 			} catch (IOException e) {
 				if (LOG.isLoggable(INFO))
 					LOG.info("Failed to bind " + scrubSocketAddress(addr));
-				tryToClose(ss);
+				tryToClose(ss, LOG, WARNING);
 			}
 		}
-		if (ss == null || !ss.isBound()) {
+		if (ss == null) {
 			LOG.info("Could not bind server socket for key agreement");
 			return null;
 		}
@@ -228,7 +228,8 @@ class LanTcpPlugin extends TcpPlugin {
 	@Override
 	public DuplexTransportConnection createKeyAgreementConnection(
 			byte[] commitment, BdfList descriptor) {
-		if (!isRunning()) return null;
+		ServerSocket ss = state.getServerSocket();
+		if (ss == null) return null;
 		InetSocketAddress remote;
 		try {
 			remote = parseSocketAddress(descriptor);
@@ -238,10 +239,9 @@ class LanTcpPlugin extends TcpPlugin {
 		}
 		if (!isConnectable(remote)) {
 			if (LOG.isLoggable(INFO)) {
-				SocketAddress local = socket.getLocalSocketAddress();
 				LOG.info(scrubSocketAddress(remote) +
 						" is not connectable from " +
-						scrubSocketAddress(local));
+						scrubSocketAddress(ss.getLocalSocketAddress()));
 			}
 			return null;
 		}
@@ -249,7 +249,7 @@ class LanTcpPlugin extends TcpPlugin {
 			if (LOG.isLoggable(INFO))
 				LOG.info("Connecting to " + scrubSocketAddress(remote));
 			Socket s = createSocket();
-			s.bind(new InetSocketAddress(socket.getInetAddress(), 0));
+			s.bind(new InetSocketAddress(ss.getInetAddress(), 0));
 			s.connect(remote);
 			s.setSoTimeout(socketTimeout);
 			if (LOG.isLoggable(INFO))
@@ -296,7 +296,7 @@ class LanTcpPlugin extends TcpPlugin {
 
 		@Override
 		public void close() {
-			IoUtils.tryToClose(ss, LOG, WARNING);
+			tryToClose(ss, LOG, WARNING);
 		}
 	}
 

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

@@ -5,6 +5,7 @@ import org.briarproject.bramble.api.Pair;
 import org.briarproject.bramble.api.data.BdfList;
 import org.briarproject.bramble.api.keyagreement.KeyAgreementListener;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.bramble.api.plugin.Backoff;
 import org.briarproject.bramble.api.plugin.ConnectionHandler;
@@ -14,7 +15,6 @@ import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
 import org.briarproject.bramble.api.properties.TransportProperties;
 import org.briarproject.bramble.api.rendezvous.KeyMaterialSource;
 import org.briarproject.bramble.api.rendezvous.RendezvousEndpoint;
-import org.briarproject.bramble.util.IoUtils;
 
 import java.io.IOException;
 import java.net.InetAddress;
@@ -22,7 +22,6 @@ import java.net.InetSocketAddress;
 import java.net.NetworkInterface;
 import java.net.ServerSocket;
 import java.net.Socket;
-import java.net.SocketAddress;
 import java.net.SocketException;
 import java.net.UnknownHostException;
 import java.util.ArrayList;
@@ -35,6 +34,8 @@ import java.util.logging.Logger;
 import java.util.regex.Pattern;
 
 import javax.annotation.Nullable;
+import javax.annotation.concurrent.GuardedBy;
+import javax.annotation.concurrent.ThreadSafe;
 
 import static java.net.NetworkInterface.getNetworkInterfaces;
 import static java.util.Collections.emptyList;
@@ -42,6 +43,10 @@ import static java.util.Collections.list;
 import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
 import static java.util.logging.Logger.getLogger;
+import static org.briarproject.bramble.api.plugin.Plugin.State.ACTIVE;
+import static org.briarproject.bramble.api.plugin.Plugin.State.DISABLED;
+import static org.briarproject.bramble.api.plugin.Plugin.State.INACTIVE;
+import static org.briarproject.bramble.util.IoUtils.tryToClose;
 import static org.briarproject.bramble.util.LogUtils.logException;
 import static org.briarproject.bramble.util.PrivacyUtils.scrubSocketAddress;
 import static org.briarproject.bramble.util.StringUtils.isNullOrEmpty;
@@ -60,9 +65,7 @@ abstract class TcpPlugin implements DuplexPlugin {
 	protected final PluginCallback callback;
 	protected final int maxLatency, maxIdleTime, socketTimeout;
 	protected final AtomicBoolean used = new AtomicBoolean(false);
-
-	protected volatile boolean running = false;
-	protected volatile ServerSocket socket = null;
+	protected final PluginState state = new PluginState();
 
 	/**
 	 * Returns zero or more socket addresses on which the plugin should listen,
@@ -86,6 +89,7 @@ abstract class TcpPlugin implements DuplexPlugin {
 	/**
 	 * Returns true if connections to the given address can be attempted.
 	 */
+	@SuppressWarnings("BooleanMethodIsAlwaysInverted")
 	protected abstract boolean isConnectable(InetSocketAddress remote);
 
 	TcpPlugin(Executor ioExecutor, Backoff backoff, PluginCallback callback,
@@ -115,14 +119,13 @@ abstract class TcpPlugin implements DuplexPlugin {
 	@Override
 	public void start() {
 		if (used.getAndSet(true)) throw new IllegalStateException();
-		running = true;
+		state.setStarted();
 		bind();
 	}
 
 	protected void bind() {
 		bindExecutor.execute(() -> {
-			if (!running) return;
-			if (socket != null && !socket.isClosed()) return;
+			if (getState() != INACTIVE) return;
 			ServerSocket ss = null;
 			for (InetSocketAddress addr : getLocalSocketAddresses()) {
 				try {
@@ -132,34 +135,28 @@ abstract class TcpPlugin implements DuplexPlugin {
 				} catch (IOException e) {
 					if (LOG.isLoggable(INFO))
 						LOG.info("Failed to bind " + scrubSocketAddress(addr));
-					tryToClose(ss);
+					tryToClose(ss, LOG, WARNING);
 				}
 			}
-			if (ss == null || !ss.isBound()) {
+			if (ss == null) {
 				LOG.info("Could not bind server socket");
 				return;
 			}
-			if (!running) {
-				tryToClose(ss);
+			if (!state.setServerSocket(ss)) {
+				LOG.info("Closing redundant server socket");
+				tryToClose(ss, LOG, WARNING);
 				return;
 			}
-			socket = ss;
 			backoff.reset();
 			InetSocketAddress local =
 					(InetSocketAddress) ss.getLocalSocketAddress();
 			setLocalSocketAddress(local);
 			if (LOG.isLoggable(INFO))
 				LOG.info("Listening on " + scrubSocketAddress(local));
-			callback.transportEnabled();
-			acceptContactConnections();
+			acceptContactConnections(ss);
 		});
 	}
 
-	protected void tryToClose(@Nullable ServerSocket ss) {
-		IoUtils.tryToClose(ss, LOG, WARNING);
-		callback.transportDisabled();
-	}
-
 	String getIpPortString(InetSocketAddress a) {
 		String addr = a.getAddress().getHostAddress();
 		int percent = addr.indexOf('%');
@@ -167,15 +164,16 @@ abstract class TcpPlugin implements DuplexPlugin {
 		return addr + ":" + a.getPort();
 	}
 
-	private void acceptContactConnections() {
-		while (isRunning()) {
+	private void acceptContactConnections(ServerSocket ss) {
+		while (true) {
 			Socket s;
 			try {
-				s = socket.accept();
+				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());
+				// This is expected when the server socket is closed
+				LOG.info("Server socket closed");
+				state.clearServerSocket(ss);
 				return;
 			}
 			if (LOG.isLoggable(INFO))
@@ -188,13 +186,18 @@ abstract class TcpPlugin implements DuplexPlugin {
 
 	@Override
 	public void stop() {
-		running = false;
-		tryToClose(socket);
+		ServerSocket ss = state.setStopped();
+		tryToClose(ss, LOG, WARNING);
 	}
 
 	@Override
-	public boolean isRunning() {
-		return running && socket != null && !socket.isClosed();
+	public State getState() {
+		return state.getState();
+	}
+
+	@Override
+	public int getReasonDisabled() {
+		return getState() == DISABLED ? REASON_STARTING_STOPPING : -1;
 	}
 
 	@Override
@@ -210,7 +213,7 @@ abstract class TcpPlugin implements DuplexPlugin {
 	@Override
 	public void poll(Collection<Pair<TransportProperties, ConnectionHandler>>
 			properties) {
-		if (!isRunning()) return;
+		if (getState() != ACTIVE) return;
 		backoff.increment();
 		for (Pair<TransportProperties, ConnectionHandler> p : properties) {
 			connect(p.getFirst(), p.getSecond());
@@ -229,14 +232,14 @@ abstract class TcpPlugin implements DuplexPlugin {
 
 	@Override
 	public DuplexTransportConnection createConnection(TransportProperties p) {
-		if (!isRunning()) return null;
+		ServerSocket ss = state.getServerSocket();
+		if (ss == null) return null;
 		for (InetSocketAddress remote : getRemoteSocketAddresses(p)) {
 			if (!isConnectable(remote)) {
 				if (LOG.isLoggable(INFO)) {
-					SocketAddress local = socket.getLocalSocketAddress();
 					LOG.info(scrubSocketAddress(remote) +
 							" is not connectable from " +
-							scrubSocketAddress(local));
+							scrubSocketAddress(ss.getLocalSocketAddress()));
 				}
 				continue;
 			}
@@ -244,7 +247,7 @@ abstract class TcpPlugin implements DuplexPlugin {
 				if (LOG.isLoggable(INFO))
 					LOG.info("Connecting to " + scrubSocketAddress(remote));
 				Socket s = createSocket();
-				s.bind(new InetSocketAddress(socket.getInetAddress(), 0));
+				s.bind(new InetSocketAddress(ss.getInetAddress(), 0));
 				s.connect(remote);
 				s.setSoTimeout(socketTimeout);
 				if (LOG.isLoggable(INFO))
@@ -327,4 +330,51 @@ abstract class TcpPlugin implements DuplexPlugin {
 			return emptyList();
 		}
 	}
+
+	@ThreadSafe
+	@NotNullByDefault
+	protected class PluginState {
+
+		@GuardedBy("this")
+		private boolean started = false, stopped = false;
+		@GuardedBy("this")
+		@Nullable
+		private ServerSocket serverSocket = null;
+
+		synchronized void setStarted() {
+			started = true;
+			callback.pluginStateChanged(getState());
+		}
+
+		@Nullable
+		synchronized ServerSocket setStopped() {
+			stopped = true;
+			ServerSocket ss = serverSocket;
+			serverSocket = null;
+			callback.pluginStateChanged(getState());
+			return ss;
+		}
+
+		@Nullable
+		synchronized ServerSocket getServerSocket() {
+			return serverSocket;
+		}
+
+		synchronized boolean setServerSocket(ServerSocket ss) {
+			if (stopped || serverSocket != null) return false;
+			serverSocket = ss;
+			callback.pluginStateChanged(getState());
+			return true;
+		}
+
+		synchronized void clearServerSocket(ServerSocket ss) {
+			if (serverSocket == ss) serverSocket = null;
+			callback.pluginStateChanged(getState());
+		}
+
+		synchronized State getState() {
+			if (!started || stopped) return DISABLED;
+			return serverSocket == null ? INACTIVE : ACTIVE;
+		}
+	}
 }

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

@@ -15,6 +15,7 @@ import org.briarproject.bramble.api.network.NetworkManager;
 import org.briarproject.bramble.api.network.NetworkStatus;
 import org.briarproject.bramble.api.network.event.NetworkStatusEvent;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.bramble.api.plugin.Backoff;
 import org.briarproject.bramble.api.plugin.ConnectionHandler;
@@ -54,6 +55,9 @@ import java.util.logging.Logger;
 import java.util.regex.Pattern;
 import java.util.zip.ZipInputStream;
 
+import javax.annotation.Nullable;
+import javax.annotation.concurrent.GuardedBy;
+import javax.annotation.concurrent.ThreadSafe;
 import javax.net.SocketFactory;
 
 import static java.util.Arrays.asList;
@@ -65,6 +69,10 @@ import static java.util.logging.Logger.getLogger;
 import static net.freehaven.tor.control.TorControlCommands.HS_ADDRESS;
 import static net.freehaven.tor.control.TorControlCommands.HS_PRIVKEY;
 import static org.briarproject.bramble.api.nullsafety.NullSafety.requireNonNull;
+import static org.briarproject.bramble.api.plugin.Plugin.State.ACTIVE;
+import static org.briarproject.bramble.api.plugin.Plugin.State.DISABLED;
+import static org.briarproject.bramble.api.plugin.Plugin.State.ENABLING;
+import static org.briarproject.bramble.api.plugin.Plugin.State.INACTIVE;
 import static org.briarproject.bramble.api.plugin.TorConstants.CONTROL_PORT;
 import static org.briarproject.bramble.api.plugin.TorConstants.ID;
 import static org.briarproject.bramble.api.plugin.TorConstants.PREF_TOR_MOBILE;
@@ -76,6 +84,10 @@ import static org.briarproject.bramble.api.plugin.TorConstants.PREF_TOR_ONLY_WHE
 import static org.briarproject.bramble.api.plugin.TorConstants.PREF_TOR_PORT;
 import static org.briarproject.bramble.api.plugin.TorConstants.PROP_ONION_V2;
 import static org.briarproject.bramble.api.plugin.TorConstants.PROP_ONION_V3;
+import static org.briarproject.bramble.api.plugin.TorConstants.REASON_BATTERY;
+import static org.briarproject.bramble.api.plugin.TorConstants.REASON_COUNTRY_BLOCKED;
+import static org.briarproject.bramble.api.plugin.TorConstants.REASON_MOBILE_DATA;
+import static org.briarproject.bramble.api.plugin.TorConstants.REASON_USER;
 import static org.briarproject.bramble.plugin.tor.TorRendezvousCrypto.SEED_BYTES;
 import static org.briarproject.bramble.util.IoUtils.copyAndClose;
 import static org.briarproject.bramble.util.IoUtils.tryToClose;
@@ -113,16 +125,14 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 	private final int maxLatency, maxIdleTime, socketTimeout;
 	private final File torDirectory, torFile, geoIpFile, obfs4File, configFile;
 	private final File doneFile, cookieFile;
-	private final ConnectionStatus connectionStatus;
 	private final AtomicBoolean used = new AtomicBoolean(false);
 
-	private volatile ServerSocket socket = null;
+	protected final PluginState state = new PluginState();
+
 	private volatile Socket controlSocket = null;
 	private volatile TorControlConnection controlConnection = null;
 	private volatile Settings settings = null;
 
-	protected volatile boolean running = false;
-
 	protected abstract int getProcessId();
 
 	protected abstract long getLastUpdateTime();
@@ -159,7 +169,6 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 		configFile = new File(torDirectory, "torrc");
 		doneFile = new File(torDirectory, "done");
 		cookieFile = new File(torDirectory, ".tor/control_auth_cookie");
-		connectionStatus = new ConnectionStatus();
 		// Don't execute more than one connection status check at a time
 		connectionStatusExecutor =
 				new PoliteExecutor("TorPlugin", ioExecutor, 1);
@@ -183,6 +192,7 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 	@Override
 	public void start() throws PluginException {
 		if (used.getAndSet(true)) throw new IllegalStateException();
+		state.setStarted();
 		if (!torDirectory.exists()) {
 			if (!torDirectory.mkdirs()) {
 				LOG.warning("Could not create Tor directory.");
@@ -258,7 +268,6 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 			// Tell Tor to exit when the control connection is closed
 			controlConnection.takeOwnership();
 			controlConnection.resetConf(singletonList(OWNER));
-			running = true;
 			// Register to receive events from the Tor process
 			controlConnection.setEventHandler(this);
 			controlConnection.setEvents(asList(EVENTS));
@@ -266,11 +275,12 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 			String phase = controlConnection.getInfo("status/bootstrap-phase");
 			if (phase != null && phase.contains("PROGRESS=100")) {
 				LOG.info("Tor has already bootstrapped");
-				connectionStatus.setBootstrapped();
+				state.setBootstrapped();
 			}
 		} catch (IOException e) {
 			throw new PluginException(e);
 		}
+		state.setTorStarted();
 		// Check whether we're online
 		updateConnectionStatus(networkManager.getNetworkStatus(),
 				batteryManager.isCharging());
@@ -393,11 +403,11 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 				tryToClose(ss, LOG, WARNING);
 				return;
 			}
-			if (!running) {
+			if (!state.setServerSocket(ss)) {
+				LOG.info("Closing redundant server socket");
 				tryToClose(ss, LOG, WARNING);
 				return;
 			}
-			socket = ss;
 			// Store the port number
 			String localPort = String.valueOf(ss.getLocalPort());
 			Settings s = new Settings();
@@ -412,7 +422,7 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 	}
 
 	private void publishHiddenService(String port) {
-		if (!running) return;
+		if (!state.isTorRunning()) return;
 		LOG.info("Creating hidden service");
 		String privKey = settings.get(HS_PRIVKEY);
 		Map<Integer, String> portLines = singletonMap(80, "127.0.0.1:" + port);
@@ -450,14 +460,15 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 	}
 
 	private void acceptContactConnections(ServerSocket ss) {
-		while (running) {
+		while (true) {
 			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());
+				// This is expected when the server socket is closed
+				LOG.info("Server socket closed");
+				state.clearServerSocket(ss);
 				return;
 			}
 			LOG.info("Connection received");
@@ -467,10 +478,8 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 	}
 
 	protected void enableNetwork(boolean enable) throws IOException {
-		if (!running) return;
-		connectionStatus.enableNetwork(enable);
+		state.enableNetwork(enable);
 		controlConnection.setConf("DisableNetwork", enable ? "0" : "1");
-		if (!enable) callback.transportDisabled();
 	}
 
 	private void enableBridges(boolean enable, boolean needsMeek)
@@ -494,9 +503,8 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 
 	@Override
 	public void stop() {
-		running = false;
-		tryToClose(socket, LOG, WARNING);
-		callback.transportDisabled();
+		ServerSocket ss = state.setStopped();
+		tryToClose(ss, LOG, WARNING);
 		if (controlSocket != null && controlConnection != null) {
 			try {
 				LOG.info("Stopping Tor");
@@ -510,8 +518,13 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 	}
 
 	@Override
-	public boolean isRunning() {
-		return running && connectionStatus.isConnected();
+	public State getState() {
+		return state.getState();
+	}
+
+	@Override
+	public int getReasonDisabled() {
+		return state.getReasonDisabled();
 	}
 
 	@Override
@@ -527,7 +540,7 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 	@Override
 	public void poll(Collection<Pair<TransportProperties, ConnectionHandler>>
 			properties) {
-		if (!isRunning()) return;
+		if (getState() != ACTIVE) return;
 		backoff.increment();
 		for (Pair<TransportProperties, ConnectionHandler> p : properties) {
 			connect(p.getFirst(), p.getSecond());
@@ -546,7 +559,7 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 
 	@Override
 	public DuplexTransportConnection createConnection(TransportProperties p) {
-		if (!isRunning()) return null;
+		if (getState() != ACTIVE) return null;
 		String bestOnion = null;
 		String onion2 = p.get(PROP_ONION_V2);
 		String onion3 = p.get(PROP_ONION_V3);
@@ -634,8 +647,8 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 								new TorTransportConnection(this, s));
 					}
 				} catch (IOException e) {
-					// This is expected when the socket is closed
-					if (LOG.isLoggable(INFO)) LOG.info(e.toString());
+					// This is expected when the server socket is closed
+					LOG.info("Rendezvous server socket closed");
 				}
 			});
 			Map<Integer, String> portLines =
@@ -663,10 +676,9 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 	@Override
 	public void circuitStatus(String status, String id, String path) {
 		if (status.equals("BUILT") &&
-				connectionStatus.getAndSetCircuitBuilt()) {
+				state.getAndSetCircuitBuilt()) {
 			LOG.info("First circuit built");
 			backoff.reset();
-			if (isRunning()) callback.transportEnabled();
 		}
 	}
 
@@ -697,9 +709,8 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 	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();
+			state.setBootstrapped();
 			backoff.reset();
-			if (isRunning()) callback.transportEnabled();
 		}
 	}
 
@@ -736,7 +747,7 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 	private void disableNetwork() {
 		connectionStatusExecutor.execute(() -> {
 			try {
-				enableNetwork(false);
+				if (state.isTorRunning()) enableNetwork(false);
 			} catch (IOException ex) {
 				logException(LOG, WARNING, ex);
 			}
@@ -746,7 +757,7 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 	private void updateConnectionStatus(NetworkStatus status,
 			boolean charging) {
 		connectionStatusExecutor.execute(() -> {
-			if (!running) return;
+			if (!state.isTorRunning()) return;
 			boolean online = status.isConnected();
 			boolean wifi = status.isWifi();
 			String country = locationUtils.getCurrentCountry();
@@ -762,47 +773,67 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 
 			if (LOG.isLoggable(INFO)) {
 				LOG.info("Online: " + online + ", wifi: " + wifi);
-				if ("".equals(country)) LOG.info("Country code unknown");
+				if (country.isEmpty()) LOG.info("Country code unknown");
 				else LOG.info("Country code: " + country);
 				LOG.info("Charging: " + charging);
 			}
 
-			try {
-				if (!online) {
-					LOG.info("Disabling network, device is offline");
-					enableNetwork(false);
-				} else if (!charging && onlyWhenCharging) {
-					LOG.info("Disabling network, device is on battery");
-					enableNetwork(false);
-				} else if (network == PREF_TOR_NETWORK_NEVER ||
-						(!useMobile && !wifi)) {
-					LOG.info("Disabling network, device is using mobile data");
-					enableNetwork(false);
-				} else if (automatic && blocked && !bridgesWork) {
-					LOG.info("Disabling network, country is blocked");
-					enableNetwork(false);
-				} else if (network == PREF_TOR_NETWORK_WITH_BRIDGES ||
+			boolean enableNetwork = false, enableBridges = false;
+			boolean useMeek = false, enableConnectionPadding = false;
+			boolean disabledBySettings = false;
+			int reasonDisabled = REASON_STARTING_STOPPING;
+
+			if (!online) {
+				LOG.info("Disabling network, device is offline");
+			} else if (network == PREF_TOR_NETWORK_NEVER) {
+				LOG.info("Disabling network, user has disabled Tor");
+				disabledBySettings = true;
+				reasonDisabled = REASON_USER;
+			} else if (!charging && onlyWhenCharging) {
+				LOG.info("Disabling network, device is on battery");
+				disabledBySettings = true;
+				reasonDisabled = REASON_BATTERY;
+			} else if (!useMobile && !wifi) {
+				LOG.info("Disabling network, device is using mobile data");
+				disabledBySettings = true;
+				reasonDisabled = REASON_MOBILE_DATA;
+			} else if (automatic && blocked && !bridgesWork) {
+				LOG.info("Disabling network, country is blocked");
+				disabledBySettings = true;
+				reasonDisabled = REASON_COUNTRY_BLOCKED;
+			} else {
+				LOG.info("Enabling network");
+				enableNetwork = true;
+				if (network == PREF_TOR_NETWORK_WITH_BRIDGES ||
 						(automatic && bridgesWork)) {
 					if (circumventionProvider.needsMeek(country)) {
-						LOG.info("Enabling network, using meek bridges");
-						enableBridges(true, true);
+						LOG.info("Using meek bridges");
+						enableBridges = true;
+						useMeek = true;
 					} else {
-						LOG.info("Enabling network, using obfs4 bridges");
-						enableBridges(true, false);
+						LOG.info("Using obfs4 bridges");
+						enableBridges = true;
 					}
-					enableNetwork(true);
 				} else {
-					LOG.info("Enabling network, not using bridges");
-					enableBridges(false, false);
-					enableNetwork(true);
+					LOG.info("Not using bridges");
 				}
-				if (online && wifi && charging) {
+				if (wifi && charging) {
 					LOG.info("Enabling connection padding");
-					enableConnectionPadding(true);
+					enableConnectionPadding = true;
 				} else {
 					LOG.info("Disabling connection padding");
-					enableConnectionPadding(false);
 				}
+			}
+
+
+			state.setDisabledBySettings(disabledBySettings, reasonDisabled);
+
+			try {
+				if (enableNetwork) {
+					enableBridges(enableBridges, useMeek);
+					enableConnectionPadding(enableConnectionPadding);
+				}
+				enableNetwork(enableNetwork);
 			} catch (IOException e) {
 				logException(LOG, WARNING, e);
 			}
@@ -810,33 +841,98 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 	}
 
 	private void enableConnectionPadding(boolean enable) throws IOException {
-		if (!running) return;
 		controlConnection.setConf("ConnectionPadding", enable ? "1" : "0");
 	}
 
-	private static class ConnectionStatus {
+	@ThreadSafe
+	@NotNullByDefault
+	protected class PluginState {
 
-		// All of the following are locking: this
-		private boolean networkEnabled = false;
-		private boolean bootstrapped = false, circuitBuilt = false;
+		@GuardedBy("this")
+		private boolean started = false,
+				stopped = false,
+				torStarted = false,
+				networkInitialised = false,
+				networkEnabled = false,
+				bootstrapped = false,
+				circuitBuilt = false,
+				disabledBySettings = false;
 
-		private synchronized void setBootstrapped() {
-			bootstrapped = true;
+		@GuardedBy("this")
+		private int reasonDisabled = REASON_STARTING_STOPPING;
+
+		@GuardedBy("this")
+		@Nullable
+		private ServerSocket serverSocket = null;
+
+		synchronized void setStarted() {
+			started = true;
+			callback.pluginStateChanged(getState());
 		}
 
-		private synchronized boolean getAndSetCircuitBuilt() {
+		synchronized void setTorStarted() {
+			torStarted = true;
+		}
+
+		@SuppressWarnings("BooleanMethodIsAlwaysInverted")
+		synchronized boolean isTorRunning() {
+			return torStarted && !stopped;
+		}
+
+		@Nullable
+		synchronized ServerSocket setStopped() {
+			stopped = true;
+			ServerSocket ss = serverSocket;
+			serverSocket = null;
+			callback.pluginStateChanged(getState());
+			return ss;
+		}
+
+		synchronized void setBootstrapped() {
+			bootstrapped = true;
+			callback.pluginStateChanged(getState());
+		}
+
+		synchronized boolean getAndSetCircuitBuilt() {
 			boolean firstCircuit = !circuitBuilt;
 			circuitBuilt = true;
+			callback.pluginStateChanged(getState());
 			return firstCircuit;
 		}
 
-		private synchronized void enableNetwork(boolean enable) {
+		synchronized void enableNetwork(boolean enable) {
+			networkInitialised = true;
 			networkEnabled = enable;
 			if (!enable) circuitBuilt = false;
+			callback.pluginStateChanged(getState());
 		}
 
-		private synchronized boolean isConnected() {
-			return networkEnabled && bootstrapped && circuitBuilt;
+		synchronized void setDisabledBySettings(boolean disabledBySettings,
+				int reasonDisabled) {
+			this.disabledBySettings = disabledBySettings;
+			this.reasonDisabled = reasonDisabled;
+			callback.pluginStateChanged(getState());
+		}
+
+		synchronized boolean setServerSocket(ServerSocket ss) {
+			if (stopped || serverSocket != null) return false;
+			serverSocket = ss;
+			return true;
+		}
+
+		synchronized void clearServerSocket(ServerSocket ss) {
+			if (serverSocket == ss) serverSocket = null;
+		}
+
+		synchronized State getState() {
+			if (!started || stopped || disabledBySettings) return DISABLED;
+			if (!networkInitialised) return ENABLING;
+			if (!networkEnabled) return INACTIVE;
+			return bootstrapped && circuitBuilt ? ACTIVE : ENABLING;
+		}
+
+		synchronized int getReasonDisabled() {
+			return getState() == DISABLED ? reasonDisabled : -1;
 		}
 	}
 }

bramble-core/src/main/java/org/briarproject/bramble/rendezvous/RendezvousPollerImpl.java

@@ -31,8 +31,8 @@ import org.briarproject.bramble.api.plugin.TransportConnectionWriter;
 import org.briarproject.bramble.api.plugin.TransportId;
 import org.briarproject.bramble.api.plugin.duplex.DuplexPlugin;
 import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
-import org.briarproject.bramble.api.plugin.event.TransportDisabledEvent;
-import org.briarproject.bramble.api.plugin.event.TransportEnabledEvent;
+import org.briarproject.bramble.api.plugin.event.TransportActiveEvent;
+import org.briarproject.bramble.api.plugin.event.TransportInactiveEvent;
 import org.briarproject.bramble.api.properties.TransportProperties;
 import org.briarproject.bramble.api.rendezvous.KeyMaterialSource;
 import org.briarproject.bramble.api.rendezvous.RendezvousEndpoint;
@@ -269,11 +269,11 @@ class RendezvousPollerImpl implements RendezvousPoller, Service, EventListener {
 		} else if (e instanceof PendingContactRemovedEvent) {
 			PendingContactRemovedEvent p = (PendingContactRemovedEvent) e;
 			removePendingContactAsync(p.getId());
-		} else if (e instanceof TransportEnabledEvent) {
-			TransportEnabledEvent t = (TransportEnabledEvent) e;
+		} else if (e instanceof TransportActiveEvent) {
+			TransportActiveEvent t = (TransportActiveEvent) e;
 			addTransportAsync(t.getTransportId());
-		} else if (e instanceof TransportDisabledEvent) {
-			TransportDisabledEvent t = (TransportDisabledEvent) e;
+		} else if (e instanceof TransportInactiveEvent) {
+			TransportInactiveEvent t = (TransportInactiveEvent) e;
 			removeTransportAsync(t.getTransportId());
 		} else if (e instanceof RendezvousConnectionOpenedEvent) {
 			RendezvousConnectionOpenedEvent r =

bramble-core/src/main/java/org/briarproject/bramble/reporting/DevReporterImpl.java

@@ -6,7 +6,7 @@ import org.briarproject.bramble.api.event.EventListener;
 import org.briarproject.bramble.api.lifecycle.IoExecutor;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.TorConstants;
-import org.briarproject.bramble.api.plugin.event.TransportEnabledEvent;
+import org.briarproject.bramble.api.plugin.event.TransportActiveEvent;
 import org.briarproject.bramble.api.reporting.DevConfig;
 import org.briarproject.bramble.api.reporting.DevReporter;
 import org.briarproject.bramble.util.IoUtils;
@@ -92,8 +92,8 @@ class DevReporterImpl implements DevReporter, EventListener {
 
 	@Override
 	public void eventOccurred(Event e) {
-		if (e instanceof TransportEnabledEvent) {
-			TransportEnabledEvent t = (TransportEnabledEvent) e;
+		if (e instanceof TransportActiveEvent) {
+			TransportActiveEvent t = (TransportActiveEvent) e;
 			if (t.getTransportId().equals(TorConstants.ID))
 				ioExecutor.execute(this::sendReports);
 		}

bramble-core/src/test/java/org/briarproject/bramble/plugin/PollerImplTest.java

@@ -13,8 +13,8 @@ import org.briarproject.bramble.api.plugin.duplex.DuplexPlugin;
 import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
 import org.briarproject.bramble.api.plugin.event.ConnectionClosedEvent;
 import org.briarproject.bramble.api.plugin.event.ConnectionOpenedEvent;
-import org.briarproject.bramble.api.plugin.event.TransportDisabledEvent;
-import org.briarproject.bramble.api.plugin.event.TransportEnabledEvent;
+import org.briarproject.bramble.api.plugin.event.TransportActiveEvent;
+import org.briarproject.bramble.api.plugin.event.TransportInactiveEvent;
 import org.briarproject.bramble.api.plugin.simplex.SimplexPlugin;
 import org.briarproject.bramble.api.properties.TransportProperties;
 import org.briarproject.bramble.api.properties.TransportPropertyManager;
@@ -322,7 +322,7 @@ public class PollerImplTest extends BrambleMockTestCase {
 	}
 
 	@Test
-	public void testPollsOnTransportEnabled() throws Exception {
+	public void testPollsOnTransportActivated() throws Exception {
 		DuplexPlugin plugin = context.mock(DuplexPlugin.class);
 
 		context.checking(new Expectations() {{
@@ -361,7 +361,7 @@ public class PollerImplTest extends BrambleMockTestCase {
 					pairOf(equal(properties), any(ConnectionHandler.class)))));
 		}});
 
-		poller.eventOccurred(new TransportEnabledEvent(transportId));
+		poller.eventOccurred(new TransportActiveEvent(transportId));
 	}
 
 	@Test
@@ -402,11 +402,11 @@ public class PollerImplTest extends BrambleMockTestCase {
 			// All contacts are connected, so don't poll the plugin
 		}});
 
-		poller.eventOccurred(new TransportEnabledEvent(transportId));
+		poller.eventOccurred(new TransportActiveEvent(transportId));
 	}
 
 	@Test
-	public void testCancelsPollingOnTransportDisabled() {
+	public void testCancelsPollingOnTransportDeactivated() {
 		Plugin plugin = context.mock(Plugin.class);
 
 		context.checking(new Expectations() {{
@@ -424,11 +424,11 @@ public class PollerImplTest extends BrambleMockTestCase {
 			oneOf(scheduler).schedule(with(any(Runnable.class)), with(0L),
 					with(MILLISECONDS));
 			will(returnValue(future));
-			// The plugin is disabled before the task runs - cancel the task
+			// The plugin is deactivated before the task runs - cancel the task
 			oneOf(future).cancel(false);
 		}});
 
-		poller.eventOccurred(new TransportEnabledEvent(transportId));
-		poller.eventOccurred(new TransportDisabledEvent(transportId));
+		poller.eventOccurred(new TransportActiveEvent(transportId));
+		poller.eventOccurred(new TransportInactiveEvent(transportId));
 	}
 }

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

@@ -4,6 +4,7 @@ import org.briarproject.bramble.api.data.BdfList;
 import org.briarproject.bramble.api.keyagreement.KeyAgreementListener;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.Backoff;
+import org.briarproject.bramble.api.plugin.Plugin.State;
 import org.briarproject.bramble.api.plugin.PluginCallback;
 import org.briarproject.bramble.api.plugin.TransportConnectionReader;
 import org.briarproject.bramble.api.plugin.TransportConnectionWriter;
@@ -327,6 +328,7 @@ public class LanTcpPluginTest extends BrambleTestCase {
 		assertEquals(0, comparator.compare(linkLocal, linkLocal));
 	}
 
+	@SuppressWarnings("BooleanMethodIsAlwaysInverted")
 	private boolean systemHasLocalIpv4Address() throws Exception {
 		for (NetworkInterface i : list(getNetworkInterfaces())) {
 			for (InetAddress a : list(i.getInetAddresses())) {
@@ -365,11 +367,7 @@ public class LanTcpPluginTest extends BrambleTestCase {
 		}
 
 		@Override
-		public void transportEnabled() {
-		}
-
-		@Override
-		public void transportDisabled() {
+		public void pluginStateChanged(State newState) {
 		}
 
 		@Override

bramble-core/src/test/java/org/briarproject/bramble/rendezvous/RendezvousPollerImplTest.java

@@ -17,8 +17,8 @@ import org.briarproject.bramble.api.plugin.ConnectionManager;
 import org.briarproject.bramble.api.plugin.PluginManager;
 import org.briarproject.bramble.api.plugin.TransportId;
 import org.briarproject.bramble.api.plugin.duplex.DuplexPlugin;
-import org.briarproject.bramble.api.plugin.event.TransportDisabledEvent;
-import org.briarproject.bramble.api.plugin.event.TransportEnabledEvent;
+import org.briarproject.bramble.api.plugin.event.TransportActiveEvent;
+import org.briarproject.bramble.api.plugin.event.TransportInactiveEvent;
 import org.briarproject.bramble.api.properties.TransportProperties;
 import org.briarproject.bramble.api.rendezvous.KeyMaterialSource;
 import org.briarproject.bramble.api.rendezvous.RendezvousEndpoint;
@@ -178,10 +178,10 @@ public class RendezvousPollerImplTest extends BrambleMockTestCase {
 		rendezvousPoller.startService();
 		context.assertIsSatisfied();
 
-		// Enable the transport - no endpoints should be created yet
+		// Activate the transport - no endpoints should be created yet
 		expectGetPlugin();
 
-		rendezvousPoller.eventOccurred(new TransportEnabledEvent(transportId));
+		rendezvousPoller.eventOccurred(new TransportActiveEvent(transportId));
 		context.assertIsSatisfied();
 
 		// Add the pending contact - endpoint should be created and polled
@@ -212,8 +212,8 @@ public class RendezvousPollerImplTest extends BrambleMockTestCase {
 				new PendingContactRemovedEvent(pendingContact.getId()));
 		context.assertIsSatisfied();
 
-		// Disable the transport - endpoint is already closed
-		rendezvousPoller.eventOccurred(new TransportDisabledEvent(transportId));
+		// Deactivate the transport - endpoint is already closed
+		rendezvousPoller.eventOccurred(new TransportInactiveEvent(transportId));
 	}
 
 	@Test
@@ -230,10 +230,10 @@ public class RendezvousPollerImplTest extends BrambleMockTestCase {
 		rendezvousPoller.startService();
 		context.assertIsSatisfied();
 
-		// Enable the transport - no endpoints should be created yet
+		// Activate the transport - no endpoints should be created yet
 		expectGetPlugin();
 
-		rendezvousPoller.eventOccurred(new TransportEnabledEvent(transportId));
+		rendezvousPoller.eventOccurred(new TransportActiveEvent(transportId));
 		context.assertIsSatisfied();
 
 		// Add the pending contact - endpoint should be created and polled
@@ -269,12 +269,12 @@ public class RendezvousPollerImplTest extends BrambleMockTestCase {
 				new PendingContactRemovedEvent(pendingContact.getId()));
 		context.assertIsSatisfied();
 
-		// Disable the transport - endpoint is already closed
-		rendezvousPoller.eventOccurred(new TransportDisabledEvent(transportId));
+		// Deactivate the transport - endpoint is already closed
+		rendezvousPoller.eventOccurred(new TransportInactiveEvent(transportId));
 	}
 
 	@Test
-	public void testCreatesAndClosesEndpointsWhenTransportIsEnabledAndDisabled()
+	public void testCreatesAndClosesEndpointsWhenTransportIsActivatedAndDeactivated()
 			throws Exception {
 		long beforeExpiry = pendingContact.getTimestamp();
 
@@ -292,19 +292,19 @@ public class RendezvousPollerImplTest extends BrambleMockTestCase {
 				new PendingContactAddedEvent(pendingContact));
 		context.assertIsSatisfied();
 
-		// Enable the transport - endpoint should be created
+		// Activate the transport - endpoint should be created
 		expectGetPlugin();
 		expectCreateEndpoint();
 		expectStateChangedEvent(WAITING_FOR_CONNECTION);
 
-		rendezvousPoller.eventOccurred(new TransportEnabledEvent(transportId));
+		rendezvousPoller.eventOccurred(new TransportActiveEvent(transportId));
 		context.assertIsSatisfied();
 
-		// Disable the transport - endpoint should be closed
+		// Deactivate the transport - endpoint should be closed
 		expectCloseEndpoint();
 		expectStateChangedEvent(OFFLINE);
 
-		rendezvousPoller.eventOccurred(new TransportDisabledEvent(transportId));
+		rendezvousPoller.eventOccurred(new TransportInactiveEvent(transportId));
 		context.assertIsSatisfied();
 
 		// Remove the pending contact - endpoint is already closed