Bump version numbers for 1.4.8 release.

Update tor bridges

See merge request briar/briar!1653

.gitlab-ci.yml

@@ -32,8 +32,9 @@ test:
   extends: .base-test
   stage: test
   script:
-    - ./gradlew --no-daemon -Djava.security.egd=file:/dev/urandom animalSnifferMain animalSnifferTest
+    - ./gradlew -Djava.security.egd=file:/dev/urandom animalSnifferMain animalSnifferTest
-    - ./gradlew --no-daemon -Djava.security.egd=file:/dev/urandom compileOfficialDebugAndroidTestSources compileScreenshotDebugAndroidTestSources check
+    - ./gradlew -Djava.security.egd=file:/dev/urandom assembleOfficialDebug :briar-headless:linuxJars
+    - ./gradlew -Djava.security.egd=file:/dev/urandom compileOfficialDebugAndroidTestSources compileScreenshotDebugAndroidTestSources check
   rules:
     - if: '$CI_PIPELINE_SOURCE == "merge_request_event"'
       when: always
@@ -61,7 +62,7 @@ android test:
     when: on_failure
   rules:
     - if: '$CI_PIPELINE_SOURCE == "schedule"'
-      when: on_success
+      when: manual
     - if: '$CI_PIPELINE_SOURCE == "merge_request_event"'
       changes:
         - briar-android/**/*
@@ -84,35 +85,44 @@ test_reproducible:
 
 .optional_tests:
   stage: optional_tests
-  before_script:
+  extends: .base-test
-    - set -e
-    - export GRADLE_USER_HOME=$PWD/.gradle
-
-  cache:
-    key: "$CI_COMMIT_REF_SLUG"
-    paths:
-      - .gradle/wrapper
-      - .gradle/caches
-
-  script:
-    - OPTIONAL_TESTS=org.briarproject.bramble.plugin.tor.BridgeTest ./gradlew --info bramble-java:test --tests BridgeTest
-
-  after_script:
-    # these file change every time but should not be cached
-    - rm -f $GRADLE_USER_HOME/caches/modules-2/modules-2.lock
-    - rm -fr $GRADLE_USER_HOME/caches/*/plugin-resolution/
 
 bridge test:
   extends: .optional_tests
   rules:
     - if: '$CI_PIPELINE_SOURCE == "schedule"'
       when: on_success
-      allow_failure: true
+      allow_failure: false
     - if: '$CI_COMMIT_TAG == null'
       when: manual
       allow_failure: true
+  script:
+    - OPTIONAL_TESTS=org.briarproject.bramble.plugin.tor.BridgeTest ./gradlew --info bramble-java:test --tests BridgeTest
+  timeout: 3h
+
+mailbox integration test:
+  extends: .optional_tests
+  rules:
+    - if: '$CI_PIPELINE_SOURCE == "schedule"'
+      when: on_success
+    - if: '$CI_COMMIT_TAG == null'
+      when: manual
+      allow_failure: true # TODO figure out how not to allow failure while leaving this optional
+  script:
+    # start mailbox
+    - cd /opt && git clone --depth 1 https://code.briarproject.org/briar/briar-mailbox.git briar-mailbox
+    - cd briar-mailbox
+    - mkdir -p /root/.local/share # create directory that mailbox (currently) expects to exist
+    - ./gradlew run --args="--debug --setup-token 54686973206973206120736574757020746f6b656e20666f722042726961722e" &
+    # run mailbox integration test once mailbox has started
+    - cd "$CI_PROJECT_DIR"
+    - bramble-core/src/test/bash/wait-for-mailbox.sh
+    - OPTIONAL_TESTS=org.briarproject.bramble.mailbox.MailboxIntegrationTest ./gradlew --info bramble-core:test --tests MailboxIntegrationTest
 
 pre_release_tests:
   extends: .optional_tests
+  script:
+    - OPTIONAL_TESTS=org.briarproject.bramble.plugin.tor.BridgeTest ./gradlew --info bramble-java:test --tests BridgeTest
+  timeout: 3h
   only:
     - tags

README.md

@@ -22,6 +22,15 @@ our site.
 
 [Wiki](https://code.briarproject.org/briar/briar/-/wikis/home)
 
+## Reproducible builds
+
+We provide [docker images](https://code.briarproject.org/briar/briar-reproducer#briar-reproducer)
+to ease the task of verifying that the published APK binaries
+include nothing but our publicly available source code.
+
+You can either use those images or use them as a blueprint to build your own environment
+for reproduction.
+
 ## Donate
 
 [![Donate using Liberapay](https://briarproject.org/img/liberapay.svg)](https://liberapay.com/Briar/donate) [![Flattr this](https://briarproject.org/img/flattr-badge-large.png "Flattr this")](https://flattr.com/t/592836/)   

bramble-android/build.gradle

@@ -15,8 +15,8 @@ android {
 	defaultConfig {
 		minSdkVersion 16
 		targetSdkVersion 30
-		versionCode 10401
+		versionCode 10408
-		versionName "1.4.1"
+		versionName "1.4.8"
 		consumerProguardFiles 'proguard-rules.txt'
 
 		testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
@@ -42,8 +42,8 @@ configurations {
 
 dependencies {
 	implementation project(path: ':bramble-core', configuration: 'default')
-	tor 'org.briarproject:tor-android:0.3.5.15'
+	tor "org.briarproject:tor-android:$tor_version"
-	tor 'org.briarproject:obfs4proxy-android:0.0.12-dev-40245c4a@zip'
+	tor "org.briarproject:obfs4proxy-android:$obfs4proxy_version"
 
 	annotationProcessor "com.google.dagger:dagger-compiler:$dagger_version"
 
@@ -53,7 +53,7 @@ dependencies {
 	testImplementation "junit:junit:$junit_version"
 	testImplementation "org.jmock:jmock:$jmock_version"
 	testImplementation "org.jmock:jmock-junit4:$jmock_version"
-	testImplementation "org.jmock:jmock-legacy:$jmock_version"
+	testImplementation "org.jmock:jmock-imposters:$jmock_version"
 }
 
 def torBinariesDir = 'src/main/res/raw'
@@ -70,11 +70,6 @@ clean.dependsOn cleanTorBinaries
 
 task unpackTorBinaries {
 	doLast {
-		copy {
-			from configurations.tor.collect { zipTree(it) }
-			into torBinariesDir
-			include 'geoip.zip'
-		}
 		configurations.tor.each { outer ->
 			zipTree(outer).each { inner ->
 				if (inner.name.endsWith('_arm_pie.zip')) {

bramble-android/proguard-rules.txt

@@ -1,6 +1,8 @@
--keep,includedescriptorclasses class org.briarproject.** { *; }
+# Keep the H2 classes that are loaded via reflection
-
+-keep class org.h2.Driver { *; }
--keep class org.h2.** { *; }
+-keep class org.h2.engine.Engine { *; }
+-keep class org.h2.store.fs.** { *; }
+# Don't warn about unused dependencies of H2 classes
 -dontwarn org.h2.**
 -dontnote org.h2.**
 
@@ -15,5 +17,4 @@
 -dontwarn sun.misc.Unsafe
 -dontnote com.google.common.**
 
-# UPnP library isn't used
+-dontwarn com.fasterxml.jackson.databind.ext.Java7SupportImpl
--dontwarn org.bitlet.weupnp.**

bramble-android/src/main/java/org/briarproject/bramble/network/AndroidNetworkManager.java

@@ -11,7 +11,10 @@ import android.net.LinkAddress;
 import android.net.LinkProperties;
 import android.net.Network;
 import android.net.NetworkInfo;
+import android.net.wifi.WifiInfo;
+import android.net.wifi.WifiManager;
 
+import org.briarproject.bramble.api.Cancellable;
 import org.briarproject.bramble.api.event.EventBus;
 import org.briarproject.bramble.api.event.EventExecutor;
 import org.briarproject.bramble.api.lifecycle.Service;
@@ -21,7 +24,6 @@ import org.briarproject.bramble.api.network.event.NetworkStatusEvent;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.bramble.api.system.TaskScheduler;
-import org.briarproject.bramble.api.system.TaskScheduler.Cancellable;
 
 import java.net.Inet4Address;
 import java.net.InetAddress;
@@ -38,6 +40,7 @@ import javax.annotation.Nullable;
 import javax.inject.Inject;
 
 import static android.content.Context.CONNECTIVITY_SERVICE;
+import static android.content.Context.WIFI_SERVICE;
 import static android.content.Intent.ACTION_SCREEN_OFF;
 import static android.content.Intent.ACTION_SCREEN_ON;
 import static android.net.ConnectivityManager.CONNECTIVITY_ACTION;
@@ -111,15 +114,37 @@ class AndroidNetworkManager implements NetworkManager, Service {
 
 	@Override
 	public NetworkStatus getNetworkStatus() {
-		NetworkInfo net = connectivityManager.getActiveNetworkInfo();
+		// https://issuetracker.google.com/issues/175055271
-		boolean connected = net != null && net.isConnected();
+		try {
-		boolean wifi = false, ipv6Only = false;
+			NetworkInfo net = connectivityManager.getActiveNetworkInfo();
-		if (connected) {
+			boolean connected = net != null && net.isConnected();
-			wifi = net.getType() == TYPE_WIFI;
+			boolean wifi = false, ipv6Only = false;
-			if (SDK_INT >= 23) ipv6Only = isActiveNetworkIpv6Only();
+			if (connected) {
-			else ipv6Only = areAllAvailableNetworksIpv6Only();
+				wifi = net.getType() == TYPE_WIFI;
+				if (SDK_INT >= 23) ipv6Only = isActiveNetworkIpv6Only();
+				else ipv6Only = areAllAvailableNetworksIpv6Only();
+			}
+			return new NetworkStatus(connected, wifi, ipv6Only);
+		} catch (SecurityException e) {
+			logException(LOG, WARNING, e);
+			// Without the ConnectivityManager we can't detect whether we have
+			// internet access. Assume we do, which is probably less harmful
+			// than assuming we don't. Likewise, assume the connection is
+			// IPv6-only. Fall back to the WifiManager to detect whether we
+			// have a wifi connection.
+			LOG.info("ConnectivityManager is broken, guessing connectivity");
+			boolean connected = true, wifi = false, ipv6Only = true;
+			WifiManager wm = (WifiManager) app.getSystemService(WIFI_SERVICE);
+			if (wm != null) {
+				WifiInfo info = wm.getConnectionInfo();
+				if (info != null && info.getIpAddress() != 0) {
+					LOG.info("Connected to wifi");
+					wifi = true;
+					ipv6Only = false;
+				}
+			}
+			return new NetworkStatus(connected, wifi, ipv6Only);
 		}
-		return new NetworkStatus(connected, wifi, ipv6Only);
 	}
 
 	/**
@@ -130,23 +155,29 @@ class AndroidNetworkManager implements NetworkManager, Service {
 	 */
 	@TargetApi(23)
 	private boolean isActiveNetworkIpv6Only() {
-		Network net = connectivityManager.getActiveNetwork();
+		// https://issuetracker.google.com/issues/175055271
-		if (net == null) {
+		try {
-			LOG.info("No active network");
+			Network net = connectivityManager.getActiveNetwork();
+			if (net == null) {
+				LOG.info("No active network");
+				return false;
+			}
+			LinkProperties props = connectivityManager.getLinkProperties(net);
+			if (props == null) {
+				LOG.info("No link properties for active network");
+				return false;
+			}
+			boolean hasIpv6Unicast = false;
+			for (LinkAddress linkAddress : props.getLinkAddresses()) {
+				InetAddress addr = linkAddress.getAddress();
+				if (addr instanceof Inet4Address) return false;
+				if (!addr.isMulticastAddress()) hasIpv6Unicast = true;
+			}
+			return hasIpv6Unicast;
+		} catch (SecurityException e) {
+			logException(LOG, WARNING, e);
 			return false;
 		}
-		LinkProperties props = connectivityManager.getLinkProperties(net);
-		if (props == null) {
-			LOG.info("No link properties for active network");
-			return false;
-		}
-		boolean hasIpv6Unicast = false;
-		for (LinkAddress linkAddress : props.getLinkAddresses()) {
-			InetAddress addr = linkAddress.getAddress();
-			if (addr instanceof Inet4Address) return false;
-			if (!addr.isMulticastAddress()) hasIpv6Unicast = true;
-		}
-		return hasIpv6Unicast;
 	}
 
 	/**

bramble-android/src/main/java/org/briarproject/bramble/plugin/file/AndroidRemovableDrivePlugin.java

@@ -32,13 +32,22 @@ class AndroidRemovableDrivePlugin extends RemovableDrivePlugin {
 	InputStream openInputStream(TransportProperties p) throws IOException {
 		String uri = p.get(PROP_URI);
 		if (isNullOrEmpty(uri)) throw new IllegalArgumentException();
-		return app.getContentResolver().openInputStream(Uri.parse(uri));
+		try {
+			return app.getContentResolver().openInputStream(Uri.parse(uri));
+		} catch (SecurityException e) {
+			throw new IOException(e);
+		}
 	}
 
 	@Override
 	OutputStream openOutputStream(TransportProperties p) throws IOException {
 		String uri = p.get(PROP_URI);
 		if (isNullOrEmpty(uri)) throw new IllegalArgumentException();
-		return app.getContentResolver().openOutputStream(Uri.parse(uri));
+		try {
+			return app.getContentResolver()
+					.openOutputStream(Uri.parse(uri), "wt");
+		} catch (SecurityException e) {
+			throw new IOException(e);
+		}
 	}
 }

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

@@ -175,16 +175,24 @@ class AndroidLanTcpPlugin extends LanTcpPlugin {
 	@TargetApi(21)
 	@Nullable
 	private InetAddress getWifiClientIpv6Address() {
-		for (Network net : connectivityManager.getAllNetworks()) {
+		// https://issuetracker.google.com/issues/175055271
-			NetworkCapabilities caps =
+		try {
-					connectivityManager.getNetworkCapabilities(net);
+			for (Network net : connectivityManager.getAllNetworks()) {
-			if (caps == null || !caps.hasTransport(TRANSPORT_WIFI)) continue;
+				NetworkCapabilities caps =
-			LinkProperties props = connectivityManager.getLinkProperties(net);
+						connectivityManager.getNetworkCapabilities(net);
-			if (props == null) continue;
+				if (caps == null || !caps.hasTransport(TRANSPORT_WIFI)) {
-			for (LinkAddress linkAddress : props.getLinkAddresses()) {
+					continue;
-				InetAddress addr = linkAddress.getAddress();
+				}
-				if (isIpv6LinkLocalAddress(addr)) return addr;
+				LinkProperties props =
+						connectivityManager.getLinkProperties(net);
+				if (props == null) continue;
+				for (LinkAddress linkAddress : props.getLinkAddresses()) {
+					InetAddress addr = linkAddress.getAddress();
+					if (isIpv6LinkLocalAddress(addr)) return addr;
+				}
 			}
+		} catch (SecurityException e) {
+			logException(LOG, WARNING, e);
 		}
 		return null;
 	}
@@ -227,12 +235,17 @@ class AndroidLanTcpPlugin extends LanTcpPlugin {
 	// network's socket factory may try to connect via another network
 	private SocketFactory getSocketFactory() {
 		if (SDK_INT < 21) return SocketFactory.getDefault();
-		for (Network net : connectivityManager.getAllNetworks()) {
+		// https://issuetracker.google.com/issues/175055271
-			NetworkCapabilities caps =
+		try {
-					connectivityManager.getNetworkCapabilities(net);
+			for (Network net : connectivityManager.getAllNetworks()) {
-			if (caps != null && caps.hasTransport(TRANSPORT_WIFI)) {
+				NetworkCapabilities caps =
-				return net.getSocketFactory();
+						connectivityManager.getNetworkCapabilities(net);
+				if (caps != null && caps.hasTransport(TRANSPORT_WIFI)) {
+					return net.getSocketFactory();
+				}
 			}
+		} catch (SecurityException e) {
+			logException(LOG, WARNING, e);
 		}
 		LOG.warning("Could not find suitable socket factory");
 		return SocketFactory.getDefault();

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

@@ -3,6 +3,7 @@ package org.briarproject.bramble.plugin.tor;
 import android.app.Application;
 
 import org.briarproject.bramble.api.battery.BatteryManager;
+import org.briarproject.bramble.api.crypto.CryptoComponent;
 import org.briarproject.bramble.api.event.EventBus;
 import org.briarproject.bramble.api.lifecycle.IoExecutor;
 import org.briarproject.bramble.api.network.NetworkManager;
@@ -10,61 +11,35 @@ 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.PluginCallback;
-import org.briarproject.bramble.api.plugin.TorConstants;
 import org.briarproject.bramble.api.plugin.TorControlPort;
 import org.briarproject.bramble.api.plugin.TorDirectory;
 import org.briarproject.bramble.api.plugin.TorSocksPort;
-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.system.AndroidWakeLockManager;
 import org.briarproject.bramble.api.system.Clock;
 import org.briarproject.bramble.api.system.LocationUtils;
 import org.briarproject.bramble.api.system.ResourceProvider;
 import org.briarproject.bramble.api.system.WakefulIoExecutor;
-import org.briarproject.bramble.util.AndroidUtils;
 
 import java.io.File;
 import java.util.concurrent.Executor;
-import java.util.logging.Logger;
 
+import javax.annotation.Nullable;
 import javax.annotation.concurrent.Immutable;
 import javax.inject.Inject;
 import javax.net.SocketFactory;
 
+import static org.briarproject.bramble.util.AndroidUtils.getSupportedArchitectures;
+
 @Immutable
 @NotNullByDefault
-public class AndroidTorPluginFactory implements DuplexPluginFactory {
+public class AndroidTorPluginFactory extends TorPluginFactory {
 
-	private static final Logger LOG =
-			Logger.getLogger(AndroidTorPluginFactory.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, wakefulIoExecutor;
 	private final Application app;
-	private final NetworkManager networkManager;
-	private final LocationUtils locationUtils;
-	private final EventBus eventBus;
-	private final SocketFactory torSocketFactory;
-	private final BackoffFactory backoffFactory;
-	private final ResourceProvider resourceProvider;
-	private final CircumventionProvider circumventionProvider;
-	private final BatteryManager batteryManager;
 	private final AndroidWakeLockManager wakeLockManager;
-	private final Clock clock;
-	private final File torDirectory;
-	private int torSocksPort;
-	private int torControlPort;
 
 	@Inject
 	AndroidTorPluginFactory(@IoExecutor Executor ioExecutor,
 			@WakefulIoExecutor Executor wakefulIoExecutor,
-			Application app,
 			NetworkManager networkManager,
 			LocationUtils locationUtils,
 			EventBus eventBus,
@@ -73,77 +48,43 @@ public class AndroidTorPluginFactory implements DuplexPluginFactory {
 			ResourceProvider resourceProvider,
 			CircumventionProvider circumventionProvider,
 			BatteryManager batteryManager,
-			AndroidWakeLockManager wakeLockManager,
 			Clock clock,
+			CryptoComponent crypto,
 			@TorDirectory File torDirectory,
 			@TorSocksPort int torSocksPort,
-			@TorControlPort int torControlPort) {
+			@TorControlPort int torControlPort,
-		this.ioExecutor = ioExecutor;
+			Application app,
-		this.wakefulIoExecutor = wakefulIoExecutor;
+			AndroidWakeLockManager wakeLockManager) {
+		super(ioExecutor, wakefulIoExecutor, networkManager, locationUtils,
+				eventBus, torSocketFactory, backoffFactory, resourceProvider,
+				circumventionProvider, batteryManager, clock, crypto,
+				torDirectory, torSocksPort, torControlPort);
 		this.app = app;
-		this.networkManager = networkManager;
-		this.locationUtils = locationUtils;
-		this.eventBus = eventBus;
-		this.torSocketFactory = torSocketFactory;
-		this.backoffFactory = backoffFactory;
-		this.resourceProvider = resourceProvider;
-		this.circumventionProvider = circumventionProvider;
-		this.batteryManager = batteryManager;
 		this.wakeLockManager = wakeLockManager;
-		this.clock = clock;
-		this.torDirectory = torDirectory;
-		this.torSocksPort = torSocksPort;
-		this.torControlPort = torControlPort;
 	}
 
+	@Nullable
 	@Override
-	public TransportId getId() {
+	String getArchitectureForTorBinary() {
-		return TorConstants.ID;
+		for (String abi : getSupportedArchitectures()) {
-	}
+			if (abi.startsWith("x86_64")) return "x86_64_pie";
-
+			else if (abi.startsWith("x86")) return "x86_pie";
-	@Override
+			else if (abi.startsWith("arm64")) return "arm64_pie";
-	public long getMaxLatency() {
+			else if (abi.startsWith("armeabi")) return "arm_pie";
-		return MAX_LATENCY;
-	}
-
-	@Override
-	public DuplexPlugin createPlugin(PluginCallback callback) {
-
-		// Check that we have a Tor binary for this architecture
-		String architecture = null;
-		for (String abi : AndroidUtils.getSupportedArchitectures()) {
-			if (abi.startsWith("x86_64")) {
-				architecture = "x86_64";
-				break;
-			} else if (abi.startsWith("x86")) {
-				architecture = "x86";
-				break;
-			} else if (abi.startsWith("arm64")) {
-				architecture = "arm64";
-				break;
-			} else if (abi.startsWith("armeabi")) {
-				architecture = "arm";
-				break;
-			}
 		}
-		if (architecture == null) {
+		return null;
-			LOG.info("Tor is not supported on this architecture");
+	}
-			return null;
-		}
-		// Use position-independent executable
-		architecture += "_pie";
 
-		Backoff backoff = backoffFactory.createBackoff(MIN_POLLING_INTERVAL,
+	@Override
-				MAX_POLLING_INTERVAL, BACKOFF_BASE);
+	TorPlugin createPluginInstance(Backoff backoff,
-		TorRendezvousCrypto torRendezvousCrypto = new TorRendezvousCryptoImpl();
+			TorRendezvousCrypto torRendezvousCrypto, PluginCallback callback,
-		AndroidTorPlugin plugin = new AndroidTorPlugin(ioExecutor,
+			String architecture) {
+		return new AndroidTorPlugin(ioExecutor,
 				wakefulIoExecutor, app, networkManager, locationUtils,
 				torSocketFactory, clock, resourceProvider,
 				circumventionProvider, batteryManager, wakeLockManager,
 				backoff, torRendezvousCrypto, callback, architecture,
 				MAX_LATENCY, MAX_IDLE_TIME, torDirectory, torSocksPort,
 				torControlPort);
-		eventBus.addListener(plugin);
-		return plugin;
 	}
 }

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

@@ -8,6 +8,7 @@ import android.content.Intent;
 import android.os.Process;
 import android.os.SystemClock;
 
+import org.briarproject.bramble.api.Cancellable;
 import org.briarproject.bramble.api.lifecycle.Service;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.system.AlarmListener;
@@ -116,10 +117,12 @@ class AndroidTaskScheduler implements TaskScheduler, Service, AlarmListener {
 		long dueMillis = now + MILLISECONDS.convert(delay, unit);
 		Runnable wakeful = () ->
 				wakeLockManager.executeWakefully(task, executor, "TaskHandoff");
-		Future<?> check = scheduleCheckForDueTasks(delay, unit);
+		// Acquire the lock before scheduling the check to ensure the check
-		ScheduledTask s = new ScheduledTask(wakeful, dueMillis, check,
+		// doesn't access the task queue before the task has been added
-				cancelled);
+		ScheduledTask s;
 		synchronized (lock) {
+			Future<?> check = scheduleCheckForDueTasks(delay, unit);
+			s = new ScheduledTask(wakeful, dueMillis, check, cancelled);
 			tasks.add(s);
 		}
 		return s;
@@ -136,6 +139,7 @@ class AndroidTaskScheduler implements TaskScheduler, Service, AlarmListener {
 		return schedule(wrapped, executor, delay, unit, cancelled);
 	}
 
+	@GuardedBy("lock")
 	private Future<?> scheduleCheckForDueTasks(long delay, TimeUnit unit) {
 		Runnable wakeful = () -> wakeLockManager.runWakefully(
 				this::runDueTasks, "TaskScheduler");
@@ -206,7 +210,7 @@ class AndroidTaskScheduler implements TaskScheduler, Service, AlarmListener {
 		private final Future<?> check;
 		private final AtomicBoolean cancelled;
 
-		public ScheduledTask(Runnable task, long dueMillis,
+		private ScheduledTask(Runnable task, long dueMillis,
 				Future<?> check, AtomicBoolean cancelled) {
 			this.task = task;
 			this.dueMillis = dueMillis;

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

@@ -4,6 +4,7 @@ import android.annotation.SuppressLint;
 import android.bluetooth.BluetoothAdapter;
 import android.content.Context;
 import android.os.Build;
+import android.os.Looper;
 import android.provider.Settings;
 
 import org.briarproject.bramble.api.Pair;
@@ -134,4 +135,8 @@ public class AndroidUtils {
 			return null;
 		}
 	}
+
+	public static boolean isUiThread() {
+		return Looper.myLooper() == Looper.getMainLooper();
+	}
 }

bramble-android/src/test/java/org/briarproject/bramble/account/AndroidAccountManagerTest.java

@@ -9,7 +9,7 @@ import org.briarproject.bramble.api.db.DatabaseConfig;
 import org.briarproject.bramble.api.identity.IdentityManager;
 import org.briarproject.bramble.test.BrambleMockTestCase;
 import org.jmock.Expectations;
-import org.jmock.lib.legacy.ClassImposteriser;
+import org.jmock.imposters.ByteBuddyClassImposteriser;
 import org.junit.After;
 import org.junit.Before;
 import org.junit.Test;
@@ -44,7 +44,7 @@ public class AndroidAccountManagerTest extends BrambleMockTestCase {
 	private AndroidAccountManager accountManager;
 
 	public AndroidAccountManagerTest() {
-		context.setImposteriser(ClassImposteriser.INSTANCE);
+		context.setImposteriser(ByteBuddyClassImposteriser.INSTANCE);
 		app = context.mock(Application.class);
 		applicationInfo = new ApplicationInfo();
 		applicationInfo.dataDir = testDir.getAbsolutePath();

bramble-android/witness.gradle

@@ -1,50 +1,50 @@
 dependencyVerification {
     verify = [
         'cglib:cglib:3.2.8:cglib-3.2.8.jar:3f64de999ecc5595dc84ca8ff0879d8a34c8623f9ef3c517a53ed59023fcb9db',
-        'com.android.tools.analytics-library:protos:27.1.3:protos-27.1.3.jar:0d9e6cff60b318baac250b6f5bb076a8161103338bf2749cdf1db8a5a13a1f12',
+        'com.android.tools.analytics-library:protos:30.0.3:protos-30.0.3.jar:f62b89dcd9de719c6a7b7e15fb1dd20e45b57222e675cf633607bd0ed6bca7e7',
-        'com.android.tools.analytics-library:shared:27.1.3:shared-27.1.3.jar:10d2a51d8f89ff4ac849888e5a9c60b10e879c30d78545ec1da4d3df7bd56ae4',
+        'com.android.tools.analytics-library:shared:30.0.3:shared-30.0.3.jar:05aa9ba3cc890354108521fdf99802565aae5dd6ca44a6ac8bb8d594d1c1cd15',
-        'com.android.tools.analytics-library:tracker:27.1.3:tracker-27.1.3.jar:589b355a2ba796cbc0a2b2295737de6661f078262e5f87cd6f540b8d011e5ebb',
+        'com.android.tools.analytics-library:tracker:30.0.3:tracker-30.0.3.jar:5d0ef35bf6733e96210b5085a2a202152921bf834d345959dce1ca3369b528df',
         'com.android.tools.build:aapt2-proto:4.1.0-alpha01-6193524:aapt2-proto-4.1.0-alpha01-6193524.jar:17e75523e1e92dd4f222c7368ee41df9e964a508232f591e265d0c499baf9dca',
-        'com.android.tools.build:apksig:4.1.3:apksig-4.1.3.jar:a851980c678ff7a6785388b9a9e8cc094788ce3c4a985ad2b19c2028fd3c631a',
+        'com.android.tools.build:apksig:7.0.3:apksig-7.0.3.jar:012337a2803c9a30dfc41dcbc6450686ee9e5f582549f7f126479f743a343ec9',
-        'com.android.tools.build:apkzlib:4.1.3:apkzlib-4.1.3.jar:475903065e7e83a8c1ba78d267c97a54dc5a04d768b535093850423d7b11f2c8',
+        'com.android.tools.build:apkzlib:7.0.3:apkzlib-7.0.3.jar:b31e53174c92db83c5cc6e7dac6734ea4e907a72e452c2bf1818dfd082c59397',
-        'com.android.tools.build:builder-model:4.1.3:builder-model-4.1.3.jar:2624a1436c3ab39dd91d3ecf9409a594b0f89ea5cab255f2e9ff11f5ee03d274',
+        'com.android.tools.build:builder-model:7.0.3:builder-model-7.0.3.jar:483f99d7494a5bed027e1e8d29111384cf535d4842f0be5a79805bd44bb68d4e',
-        'com.android.tools.build:builder-test-api:4.1.3:builder-test-api-4.1.3.jar:3d2af66726b06b53b8d6d497efcee39ff9f77eb2f8d2cce38b31502383a40d2c',
+        'com.android.tools.build:builder-test-api:7.0.3:builder-test-api-7.0.3.jar:f6de4bc2cef545e8367bf82d7c733829c7be3b0b3b8b09fd8c58f2150e59ab46',
-        'com.android.tools.build:builder:4.1.3:builder-4.1.3.jar:a40426cd6d68f6a722ef4950058c075e4547025e8c2fd78e732ad89f15176f84',
+        'com.android.tools.build:builder:7.0.3:builder-7.0.3.jar:c6952da0094b094c2ba0fe84c675622097c5d9b9f9beb53485b860320540cf1d',
-        'com.android.tools.build:gradle-api:4.1.3:gradle-api-4.1.3.jar:11b1fb9de658bdcf9290b1c1517060d0c4d93f2b27975934989ca4ac890bc077',
+        'com.android.tools.build:manifest-merger:30.0.3:manifest-merger-30.0.3.jar:72b346ba6318b4b6260e6e49df4bea5da2e12329ab6c2beb2269c49a9f51f178',
-        'com.android.tools.build:manifest-merger:27.1.3:manifest-merger-27.1.3.jar:ce8d4009b1f1584777a7ffa1da3b0551dc316bc8e08112e442c352af70f46f2d',
+        'com.android.tools.ddms:ddmlib:30.0.3:ddmlib-30.0.3.jar:7a914a68ab93393657297234e2f37b22410ae9a433cba692ce8c727c9607e3bb',
-        'com.android.tools.ddms:ddmlib:27.1.3:ddmlib-27.1.3.jar:8f76e8236d2b9eebf26378746dad025c4c7c056a02e133dae4ddef47b283c710',
+        'com.android.tools.external.com-intellij:intellij-core:30.0.3:intellij-core-30.0.3.jar:1ebe858d3f58eeaa8c06507f8ac0f1c7051e6c61f35a70f3c3967d5734d3abc5',
-        'com.android.tools.external.com-intellij:intellij-core:27.1.3:intellij-core-27.1.3.jar:652814fa099b4746fb6f10e19718e476952e8b5bac24e17d914f90650ad21808',
+        'com.android.tools.external.com-intellij:kotlin-compiler:30.0.3:kotlin-compiler-30.0.3.jar:ed00e441f427cb4e0d418287b9da30b12b7f735f9af32e6b5d3dc960b6a742fc',
-        'com.android.tools.external.com-intellij:kotlin-compiler:27.1.3:kotlin-compiler-27.1.3.jar:8d7a78d5efd213c5e467e42bd205582aad73ffc77ee5dc18eb1361c9af72f125',
+        'com.android.tools.external.org-jetbrains:uast:30.0.3:uast-30.0.3.jar:a77801bee6ff509910e459525c9c34d7f04b066ade123547f16f1917548eadea',
-        'com.android.tools.external.org-jetbrains:uast:27.1.3:uast-27.1.3.jar:aea53944a1ac6a05f12297b55290e8cbecfe54c4166260cfba4405823bfe1c78',
+        'com.android.tools.layoutlib:layoutlib-api:30.0.3:layoutlib-api-30.0.3.jar:4caa87e9ca2e11315f650d576cd59fec1793373bc3fca3f6d53c029e7534e7c4',
-        'com.android.tools.layoutlib:layoutlib-api:27.1.3:layoutlib-api-27.1.3.jar:23875ce0a8429f33a4e86cc358f658faa0ba9c576f5f05760e544b453d67d04b',
+        'com.android.tools.lint:lint-api:30.0.3:lint-api-30.0.3.jar:bcecbd2f752a6560096a9029a47d1de6bd788a51bab505c5ebfba6a18524b983',
-        'com.android.tools.lint:lint-api:27.1.3:lint-api-27.1.3.jar:97666be32bcadacd944416ea334a9575ef8f4ad0c8f333151491ff4a7df43e1c',
+        'com.android.tools.lint:lint-checks:30.0.3:lint-checks-30.0.3.jar:25a7cd42dc3ad502337f131fb8b7e873c53301db0a67b1c64dd4ae7a8eb66cec',
-        'com.android.tools.lint:lint-checks:27.1.3:lint-checks-27.1.3.jar:b2d71ae84a31490fe9ff26c706163fe245b2aea98e3eb747214c1085df444708',
+        'com.android.tools.lint:lint-gradle:30.0.3:lint-gradle-30.0.3.jar:94544d6147a809bf2fd3440e51f28a4e42e547d74aab53eefd74938cdad42c26',
-        'com.android.tools.lint:lint-gradle-api:27.1.3:lint-gradle-api-27.1.3.jar:e54131c287a2954e6ed78a3351e5e10e35a1da2f09ac443bf44b705c71b63a4d',
+        'com.android.tools.lint:lint-model:30.0.3:lint-model-30.0.3.jar:0b940a7f575c2ff5cbd038260f41dde686a93c672213881ead3ce8af3513b396',
-        'com.android.tools.lint:lint-gradle:27.1.3:lint-gradle-27.1.3.jar:6a79e48943649d63665db7b17dbaff7af93e94ab9b15072f1a4d90486294ee9f',
+        'com.android.tools.lint:lint:30.0.3:lint-30.0.3.jar:ee4f11001e0c7e3b776e0d67399ad354b19b0f168822ec2b7db47c0910ed227d',
-        'com.android.tools.lint:lint-model:27.1.3:lint-model-27.1.3.jar:acb9e792db7000e38e3c3ca21a9b14f2de6549d7a3fc92a97ffba3d06345e5bf',
+        'com.android.tools:annotations:30.0.3:annotations-30.0.3.jar:5c1944982fda8555855c4f5422fabf0dc8e2306e1f5460e9ad82dae71316bc31',
-        'com.android.tools.lint:lint:27.1.3:lint-27.1.3.jar:5a2e69d0901a3a476a5b2d5001de755868113145f5f6aa557750cfad5389a44b',
+        'com.android.tools:common:30.0.3:common-30.0.3.jar:8751efaaf2c2ddd1f0a37526c794347def6a3057ca9fc510307c13a6cf0d036f',
-        'com.android.tools:annotations:27.1.3:annotations-27.1.3.jar:904dd771883496d5dfc86619ab2555968ea4e8a29d7a5f4f7cae6fbf5429f8f5',
+        'com.android.tools:dvlib:30.0.3:dvlib-30.0.3.jar:5affafcec390041e5afd64cb924153f5e474db47ee8ccc2f555b495083141233',
-        'com.android.tools:common:27.1.3:common-27.1.3.jar:17ab4728e3ea50f047dd5937f0faf35f2c5416962ed74891057087ddc328bf96',
+        'com.android.tools:repository:30.0.3:repository-30.0.3.jar:0a40c6f16c506903ce2c609affd8228aceda73a69d93dfa42d4f02b8491449f6',
-        'com.android.tools:dvlib:27.1.3:dvlib-27.1.3.jar:cead1c0c356cbe43e6855b0330fe09ef4bec2c72e22bdb4c6e7cf7e6b1dfbc37',
+        'com.android.tools:sdk-common:30.0.3:sdk-common-30.0.3.jar:b45570a380360236ffee0f6bb593d66b673bad3834dfe0d6c9871fa7188ee0eb',
-        'com.android.tools:repository:27.1.3:repository-27.1.3.jar:99de1a178855b56b8cd91a56296f1e0a9399c445e6acc51f1d2927947cc472cb',
+        'com.android.tools:sdklib:30.0.3:sdklib-30.0.3.jar:7088f20a414fab170a21e457825e14ebe099f753558e02c8acc12c67eb412162',
-        'com.android.tools:sdk-common:27.1.3:sdk-common-27.1.3.jar:b591e2aa0f1be600795f5c9e2bf81cba9b052bee452fc86c3362b5dd9e427a14',
+        'com.android:signflinger:7.0.3:signflinger-7.0.3.jar:903a4536db3e96b4e1e1dc1e400eb0b91bf7866d9b39cd7ec94d75dde158f152',
-        'com.android.tools:sdklib:27.1.3:sdklib-27.1.3.jar:ad6c08a45fe2904d05656bdddf9f623fa5c1d16bbd7b8d6a270a0734136ae02e',
+        'com.android:zipflinger:7.0.3:zipflinger-7.0.3.jar:fd209c960a3eff7a339e6fcba07d5e9ef4604d1633c69ab2df987460d9804140',
-        'com.android:signflinger:4.1.3:signflinger-4.1.3.jar:f3103b55ccdc8dd9ee2517eb26af93b904d41303726594372d0df59d51156e5c',
+        'com.beust:jcommander:1.78:jcommander-1.78.jar:7891debb84b5f83e9bd57593ebece3399abbe0fd938cf306b3534c57913b9615',
-        'com.android:zipflinger:4.1.3:zipflinger-4.1.3.jar:48569896c0497268308a8014c66eb0f2bace2b9e2fc9390f3012823fb86387d5',
+        'com.github.javaparser:javaparser-core:3.17.0:javaparser-core-3.17.0.jar:23f5c982e1c7771423d37d52c774e8d2e80fd7ea7305ebe448797a96f67e6fca',
         'com.google.code.findbugs:annotations:3.0.1:annotations-3.0.1.jar:6b47ff0a6de0ce17cbedc3abb0828ca5bce3009d53ea47b3723ff023c4742f79',
         'com.google.code.findbugs:jsr305:3.0.2:jsr305-3.0.2.jar:766ad2a0783f2687962c8ad74ceecc38a28b9f72a2d085ee438b7813e928d0c7',
-        'com.google.code.gson:gson:2.8.5:gson-2.8.5.jar:233a0149fc365c9f6edbd683cfe266b19bdc773be98eabdaf6b3c924b48e7d81',
+        'com.google.code.gson:gson:2.8.6:gson-2.8.6.jar:c8fb4839054d280b3033f800d1f5a97de2f028eb8ba2eb458ad287e536f3f25f',
         'com.google.dagger:dagger-compiler:2.33:dagger-compiler-2.33.jar:aa8a0d8370c578fd6999802d0d90b9829377a46d2c1141e11b8f737970e7155e',
         'com.google.dagger:dagger-producers:2.33:dagger-producers-2.33.jar:5897f0b6eef799c2adfe3ccacc58c0fb374d58acb063c3ebe5366c38a8bce5c8',
         'com.google.dagger:dagger-spi:2.33:dagger-spi-2.33.jar:e2dcab2221b8afb9556ef0a1c83b0bd5f42552e254322a257330f754cdbbb9d4',
         'com.google.dagger:dagger:2.33:dagger-2.33.jar:d8798c5b8cf6b125234e33af5c6293bb9f2208ce29b57924c35b8c0be7b6bdcb',
         'com.google.errorprone:error_prone_annotations:2.2.0:error_prone_annotations-2.2.0.jar:6ebd22ca1b9d8ec06d41de8d64e0596981d9607b42035f9ed374f9de271a481a',
-        'com.google.errorprone:error_prone_annotations:2.3.2:error_prone_annotations-2.3.2.jar:357cd6cfb067c969226c442451502aee13800a24e950fdfde77bcdb4565a668d',
+        'com.google.errorprone:error_prone_annotations:2.3.4:error_prone_annotations-2.3.4.jar:baf7d6ea97ce606c53e11b6854ba5f2ce7ef5c24dddf0afa18d1260bd25b002c',
         'com.google.errorprone:javac-shaded:9-dev-r4023-3:javac-shaded-9-dev-r4023-3.jar:65bfccf60986c47fbc17c9ebab0be626afc41741e0a6ec7109e0768817a36f30',
         'com.google.googlejavaformat:google-java-format:1.5:google-java-format-1.5.jar:aa19ad7850fb85178aa22f2fddb163b84d6ce4d0035872f30d4408195ca1144e',
         'com.google.guava:failureaccess:1.0.1:failureaccess-1.0.1.jar:a171ee4c734dd2da837e4b16be9df4661afab72a41adaf31eb84dfdaf936ca26',
         'com.google.guava:guava:27.1-jre:guava-27.1-jre.jar:4a5aa70cc968a4d137e599ad37553e5cfeed2265e8c193476d7119036c536fe7',
-        'com.google.guava:guava:28.1-jre:guava-28.1-jre.jar:30beb8b8527bd07c6e747e77f1a92122c2f29d57ce347461a4a55eb26e382da4',
+        'com.google.guava:guava:30.1-jre:guava-30.1-jre.jar:e6dd072f9d3fe02a4600688380bd422bdac184caf6fe2418cfdd0934f09432aa',
         'com.google.guava:listenablefuture:9999.0-empty-to-avoid-conflict-with-guava:listenablefuture-9999.0-empty-to-avoid-conflict-with-guava.jar:b372a037d4230aa57fbeffdef30fd6123f9c0c2db85d0aced00c91b974f33f99',
         'com.google.j2objc:j2objc-annotations:1.1:j2objc-annotations-1.1.jar:2994a7eb78f2710bd3d3bfb639b2c94e219cedac0d4d084d516e78c16dddecf6',
         'com.google.j2objc:j2objc-annotations:1.3:j2objc-annotations-1.3.jar:21af30c92267bd6122c0e0b4d20cccb6641a37eaf956c6540ec471d584e64a7b',
@@ -54,63 +54,108 @@ dependencyVerification {
         'com.squareup:javapoet:1.13.0:javapoet-1.13.0.jar:4c7517e848a71b36d069d12bb3bf46a70fd4cda3105d822b0ed2e19c00b69291',
         'com.squareup:javawriter:2.5.0:javawriter-2.5.0.jar:fcfb09fb0ea0aa97d3cfe7ea792398081348e468f126b3603cb3803f240197f0',
         'com.sun.activation:javax.activation:1.2.0:javax.activation-1.2.0.jar:993302b16cd7056f21e779cc577d175a810bb4900ef73cd8fbf2b50f928ba9ce',
-        'com.sun.istack:istack-commons-runtime:3.0.7:istack-commons-runtime-3.0.7.jar:6443e10ba2e259fb821d9b6becf10db5316285fc30c53cec9d7b19a3877e7fdf',
+        'com.sun.istack:istack-commons-runtime:3.0.8:istack-commons-runtime-3.0.8.jar:4ffabb06be454a05e4398e20c77fa2b6308d4b88dfbef7ca30a76b5b7d5505ef',
-        'com.sun.xml.fastinfoset:FastInfoset:1.2.15:FastInfoset-1.2.15.jar:785861db11ca1bd0d1956682b974ad73eb19cd3e01a4b3fa82d62eca97210aec',
+        'com.sun.xml.fastinfoset:FastInfoset:1.2.16:FastInfoset-1.2.16.jar:056f3a1e144409f21ed16afc26805f58e9a21f3fce1543c42d400719d250c511',
+        'com.thoughtworks.qdox:qdox:1.12.1:qdox-1.12.1.jar:21fba22f830e9268f07cf4ab2d99e8181abbdcb0cb91ee0228eb3cb918dcdd1d',
         'commons-codec:commons-codec:1.10:commons-codec-1.10.jar:4241dfa94e711d435f29a4604a3e2de5c4aa3c165e23bd066be6fc1fc4309569',
+        'commons-io:commons-io:2.4:commons-io-2.4.jar:cc6a41dc3eaacc9e440a6bd0d2890b20d36b4ee408fe2d67122f328bb6e01581',
         'commons-logging:commons-logging:1.2:commons-logging-1.2.jar:daddea1ea0be0f56978ab3006b8ac92834afeefbd9b7e4e6316fca57df0fa636',
-        'it.unimi.dsi:fastutil:7.2.0:fastutil-7.2.0.jar:74fa208043740642f7e6eb09faba15965218ad2f50ce3020efb100136e4b591c',
+        'info.picocli:picocli:4.5.2:picocli-4.5.2.jar:b4395e9a67932616efd2245d984bf5fcd453c2c5049558c3ce959ac2af4d3fac',
-        'javax.activation:javax.activation-api:1.2.0:javax.activation-api-1.2.0.jar:43fdef0b5b6ceb31b0424b208b930c74ab58fac2ceeb7b3f6fd3aeb8b5ca4393',
+        'it.unimi.dsi:fastutil:8.4.0:fastutil-8.4.0.jar:2ad2824a4a0a0eb836b52ee2fc84ba2134f44bce7bfa54015ae3f31c710a3071',
+        'jakarta.activation:jakarta.activation-api:1.2.1:jakarta.activation-api-1.2.1.jar:8b0a0f52fa8b05c5431921a063ed866efaa41dadf2e3a7ee3e1961f2b0d9645b',
+        'jakarta.xml.bind:jakarta.xml.bind-api:2.3.2:jakarta.xml.bind-api-2.3.2.jar:69156304079bdeed9fc0ae3b39389f19b3cc4ba4443bc80508995394ead742ea',
         'javax.annotation:jsr250-api:1.0:jsr250-api-1.0.jar:a1a922d0d9b6d183ed3800dfac01d1e1eb159f0e8c6f94736931c1def54a941f',
         'javax.inject:javax.inject:1:javax.inject-1.jar:91c77044a50c481636c32d916fd89c9118a72195390452c81065080f957de7ff',
-        'javax.xml.bind:jaxb-api:2.3.1:jaxb-api-2.3.1.jar:88b955a0df57880a26a74708bc34f74dcaf8ebf4e78843a28b50eae945732b06',
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         'net.bytebuddy:byte-buddy:1.9.12:byte-buddy-1.9.12.jar:3688c3d434bebc3edc5516296a2ed0f47b65e451071b4afecad84f902f0efc11',
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         'net.jcip:jcip-annotations:1.0:jcip-annotations-1.0.jar:be5805392060c71474bf6c9a67a099471274d30b83eef84bfc4e0889a4f1dcc0',
         'net.ltgt.gradle.incap:incap:0.2:incap-0.2.jar:b625b9806b0f1e4bc7a2e3457119488de3cd57ea20feedd513db070a573a4ffd',
         'net.sf.jopt-simple:jopt-simple:4.9:jopt-simple-4.9.jar:26c5856e954b5f864db76f13b86919b59c6eecf9fd930b96baa8884626baf2f5',
         'net.sf.kxml:kxml2:2.3.0:kxml2-2.3.0.jar:f264dd9f79a1fde10ce5ecc53221eff24be4c9331c830b7d52f2f08a7b633de2',
         'org.apache-extras.beanshell:bsh:2.0b6:bsh-2.0b6.jar:a17955976070c0573235ee662f2794a78082758b61accffce8d3f8aedcd91047',
-        'org.apache.commons:commons-compress:1.12:commons-compress-1.12.jar:2c1542faf343185b7cab9c3d55c8ae5471d6d095d3887a4adefdbdf2984dc0b6',
+        'org.apache.ant:ant-antlr:1.10.9:ant-antlr-1.10.9.jar:7623dc9d0f20ea713290c6bf1a23f4c059447aef7ff9f5b2be75960f3f028d2e',
+        'org.apache.ant:ant-junit:1.10.9:ant-junit-1.10.9.jar:960bdc8827954d62206ba42d0a68a7ee4476175ba47bb113e17e77cce7394630',
+        'org.apache.ant:ant-launcher:1.10.9:ant-launcher-1.10.9.jar:fcce891f57f3be72149ff96ac2a80574165b3e0839866b95d24528f3027d50c1',
+        'org.apache.ant:ant:1.10.9:ant-1.10.9.jar:0715478af585ea80a18985613ebecdc7922122d45b2c3c970ff9b352cddb75fc',
+        'org.apache.commons:commons-compress:1.20:commons-compress-1.20.jar:0aeb625c948c697ea7b205156e112363b59ed5e2551212cd4e460bdb72c7c06e',
         'org.apache.httpcomponents:httpclient:4.5.6:httpclient-4.5.6.jar:c03f813195e7a80e3608d0ddd8da80b21696a4c92a6a2298865bf149071551c7',
         'org.apache.httpcomponents:httpcore:4.4.10:httpcore-4.4.10.jar:78ba1096561957db1b55200a159b648876430342d15d461277e62360da19f6fd',
         'org.apache.httpcomponents:httpmime:4.5.6:httpmime-4.5.6.jar:0b2b1102c18d3c7e05a77214b9b7501a6f6056174ae5604e0e256776eda7553e',
         'org.bouncycastle:bcpkix-jdk15on:1.56:bcpkix-jdk15on-1.56.jar:7043dee4e9e7175e93e0b36f45b1ec1ecb893c5f755667e8b916eb8dd201c6ca',
         'org.bouncycastle:bcprov-jdk15on:1.56:bcprov-jdk15on-1.56.jar:963e1ee14f808ffb99897d848ddcdb28fa91ddda867eb18d303e82728f878349',
-        'org.briarproject:obfs4proxy-android:0.0.12-dev-40245c4a:obfs4proxy-android-0.0.12-dev-40245c4a.zip:8ab05a8f8391be2cb5ab2b665c281a06d9e3a756bd0f95a40a36ca927866ea82',
+        'org.briarproject:obfs4proxy-android:0.0.12:obfs4proxy-android-0.0.12.jar:84159d2a4668abc40e3fccaa1f6fa0c04892863f9eb80a866ac8928d9f9a7e89',
-        'org.briarproject:tor-android:0.3.5.15:tor-android-0.3.5.15.jar:560c5070166300b396cb2f28d82d9f639ee1fb5479096a3cef67da56d39937ad',
+        'org.briarproject:tor-android:0.4.5.12-2:tor-android-0.4.5.12-2.jar:8545dbcef2bb6aa89c32bb6f8ac51f7a64bce3ae85845b3578ffdeb9b206feb9',
         'org.checkerframework:checker-compat-qual:2.5.3:checker-compat-qual-2.5.3.jar:d76b9afea61c7c082908023f0cbc1427fab9abd2df915c8b8a3e7a509bccbc6d',
         'org.checkerframework:checker-qual:2.5.2:checker-qual-2.5.2.jar:64b02691c8b9d4e7700f8ee2e742dce7ea2c6e81e662b7522c9ee3bf568c040a',
-        'org.checkerframework:checker-qual:2.8.1:checker-qual-2.8.1.jar:9103499008bcecd4e948da29b17864abb64304e15706444ae209d17ebe0575df',
+        'org.checkerframework:checker-qual:3.5.0:checker-qual-3.5.0.jar:729990b3f18a95606fc2573836b6958bcdb44cb52bfbd1b7aa9c339cff35a5a4',
-        'org.codehaus.groovy:groovy-all:2.4.15:groovy-all-2.4.15.jar:51d6c4e71782e85674239189499854359d380fb75e1a703756e3aaa5b98a5af0',
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+        'org.codehaus.groovy:groovy-astbuilder:3.0.7:groovy-astbuilder-3.0.7.jar:b290451eb1583666e906c41f7d14747b4cc96363c99c478b244634fd5dfc9013',
+        'org.codehaus.groovy:groovy-cli-picocli:3.0.7:groovy-cli-picocli-3.0.7.jar:71b4bd11fb30a9c7b5618e22122c9c5141958fb27f4dcf0068b6f715088f6916',
+        'org.codehaus.groovy:groovy-console:3.0.7:groovy-console-3.0.7.jar:0541b358b6b8e5363215026736168fccfec1d91bac678d066fa77349eeeaa5dd',
+        'org.codehaus.groovy:groovy-datetime:3.0.7:groovy-datetime-3.0.7.jar:b9823d14b1a4f94236ae2f8a471701aab17e093e1b33402b91550b5c8dd88f04',
+        'org.codehaus.groovy:groovy-docgenerator:3.0.7:groovy-docgenerator-3.0.7.jar:bf53f7a11c9eb1e278e1b8ed2714c741bcf781235c803ad3ba1555f2614573f3',
+        'org.codehaus.groovy:groovy-groovydoc:3.0.7:groovy-groovydoc-3.0.7.jar:86b24dfc23c005066ab83927cdb54177f06c9531773f2e2d2ecc9a131f7c2677',
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+        'org.codehaus.groovy:groovy-json:3.0.7:groovy-json-3.0.7.jar:df1f0ee475e3fc93a6a0d17548294e160cca5de6d9d36817a7be1fbe650de03b',
+        'org.codehaus.groovy:groovy-jsr223:3.0.7:groovy-jsr223-3.0.7.jar:1dbd969595332416193baa660fbb45743d19696eaa25fe98e591a2739e13517e',
+        'org.codehaus.groovy:groovy-macro:3.0.7:groovy-macro-3.0.7.jar:c6cc06df526b39e2c359e2435f0071594c5a1c7babafaa6c184fdd8fa931531f',
+        'org.codehaus.groovy:groovy-nio:3.0.7:groovy-nio-3.0.7.jar:db54c577882b294cd8c975ec5451596441baf54781319c61627dca0e0c2361ef',
+        'org.codehaus.groovy:groovy-servlet:3.0.7:groovy-servlet-3.0.7.jar:5b6a909bf501c209adfb6205b9e740649609074455fd979bf9da4853e6ff9a39',
+        'org.codehaus.groovy:groovy-sql:3.0.7:groovy-sql-3.0.7.jar:252bb6c74e1a9f41756ad4fbd3b0d2eddc93bb61109961dd1952a37bf2d57a64',
+        'org.codehaus.groovy:groovy-swing:3.0.7:groovy-swing-3.0.7.jar:bd942032d9328d54c6679c49a41f6caa0d4a0039ebe598493b8a647730d98cff',
+        'org.codehaus.groovy:groovy-templates:3.0.7:groovy-templates-3.0.7.jar:f119e07f650ef186ae5a4b944f9e30915b14311bad47c94a6b32de8d4f69bc80',
+        'org.codehaus.groovy:groovy-test-junit5:3.0.7:groovy-test-junit5-3.0.7.jar:c16eeea07b8e396891e266d7ba9388b24ac804237ffdd9a792b0d08969bad014',
+        'org.codehaus.groovy:groovy-test:3.0.7:groovy-test-3.0.7.jar:f71afd7c25d43017f89ea47e6de6daec971d159047dae083c1513a8422d44b90',
+        'org.codehaus.groovy:groovy-testng:3.0.7:groovy-testng-3.0.7.jar:713d5f2231bbb5712aefd362151b9ffd884aeb7ef2e773315cc54259cbdd063d',
+        'org.codehaus.groovy:groovy-xml:3.0.7:groovy-xml-3.0.7.jar:8a62e7c9ddece3e82676c4bef2f2c100f459602cd1fb6a14e94187bf863e97ff',
+        'org.codehaus.groovy:groovy:3.0.7:groovy-3.0.7.jar:51d1777e8dd1f00e60ea56e00d8a354ff5aab1f00fc8464ae8d39d71867e401f',
         'org.codehaus.mojo:animal-sniffer-annotations:1.17:animal-sniffer-annotations-1.17.jar:92654f493ecfec52082e76354f0ebf87648dc3d5cec2e3c3cdb947c016747a53',
-        'org.codehaus.mojo:animal-sniffer-annotations:1.18:animal-sniffer-annotations-1.18.jar:47f05852b48ee9baefef80fa3d8cea60efa4753c0013121dd7fe5eef2e5c729d',
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-        'org.glassfish.jaxb:jaxb-runtime:2.3.1:jaxb-runtime-2.3.1.jar:45fecfa5c8217ce1f3652ab95179790ec8cc0dec0384bca51cbeb94a293d9f2f',
+        'org.glassfish.jaxb:txw2:2.3.2:txw2-2.3.2.jar:4a6a9f483388d461b81aa9a28c685b8b74c0597993bf1884b04eddbca95f48fe',
-        'org.glassfish.jaxb:txw2:2.3.1:txw2-2.3.1.jar:34975dde1c6920f1a39791142235689bc3cd357e24d05edd8ff93b885bd68d60',
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         'org.hamcrest:hamcrest-core:2.1:hamcrest-core-2.1.jar:e09109e54a289d88506b9bfec987ddd199f4217c9464132668351b9a4f00bee9',
         'org.hamcrest:hamcrest-library:2.1:hamcrest-library-2.1.jar:b7e2b6895b3b679f0e47b6380fda391b225e9b78505db9d8bdde8d3cc8d52a21',
         'org.hamcrest:hamcrest:2.1:hamcrest-2.1.jar:ba93b2e3a562322ba432f0a1b53addcc55cb188253319a020ed77f824e692050',
-        'org.jetbrains.kotlin:kotlin-reflect:1.3.72:kotlin-reflect-1.3.72.jar:a188d9367de1c4ee9479db630985c0597b20709c83161b1430d24edb27e38c40',
+        'org.jacoco:org.jacoco.agent:0.8.3:org.jacoco.agent-0.8.3.jar:522deb254ee16a04cc8341cc8f335f5cb7232982994d961b9cf3a0454709209f',
-        'org.jetbrains.kotlin:kotlin-stdlib-common:1.3.72:kotlin-stdlib-common-1.3.72.jar:5e7d1552863e480c1628b1cc39ce230ef829f5b7230106215a05acda5172203a',
+        'org.jacoco:org.jacoco.ant:0.8.3:org.jacoco.ant-0.8.3.jar:735844e1ae15f9b875b42a27ac5cb61cc26e106d9e839e5d1c6756709b424ce0',
+        'org.jacoco:org.jacoco.core:0.8.3:org.jacoco.core-0.8.3.jar:0818437bc060a0c7cc798148f22b713702aae2771aba104444407697d578f1ea',
+        'org.jacoco:org.jacoco.report:0.8.3:org.jacoco.report-0.8.3.jar:aae08fa4ff043c807b8876cdb2d8705eb8449a55efce461baa6c09da245088c1',
+        'org.jetbrains.intellij.deps:trove4j:1.0.20181211:trove4j-1.0.20181211.jar:affb7c85a3c87bdcf69ff1dbb84de11f63dc931293934bc08cd7ab18de083601',
+        'org.jetbrains.kotlin:kotlin-reflect:1.4.32:kotlin-reflect-1.4.32.jar:dbf19e9cdaa9c3c170f3f6f6ce3922f38dfc1d7fa1cab5b7c23a19da8b5eec5b',
         'org.jetbrains.kotlin:kotlin-stdlib-common:1.4.20:kotlin-stdlib-common-1.4.20.jar:a7112c9b3cefee418286c9c9372f7af992bd1e6e030691d52f60cb36dbec8320',
-        'org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.3.72:kotlin-stdlib-jdk7-1.3.72.jar:40566c0c08d414b9413ba556ff7f8a0b04b98b9f0f424d122dd2088510efccc4',
+        'org.jetbrains.kotlin:kotlin-stdlib-common:1.4.32:kotlin-stdlib-common-1.4.32.jar:e1ff6f55ee9e7591dcc633f7757bac25a7edb1cc7f738b37ec652f10f66a4145',
-        'org.jetbrains.kotlin:kotlin-stdlib-jdk8:1.3.72:kotlin-stdlib-jdk8-1.3.72.jar:133da70cfc07b56094282eac5c59bccd59f167ee2ead22e5282876d8bc10bf95',
+        'org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.4.32:kotlin-stdlib-jdk7-1.4.32.jar:5f801e75ca27d8791c14b07943c608da27620d910a8093022af57f543d5d98b6',
-        'org.jetbrains.kotlin:kotlin-stdlib:1.3.72:kotlin-stdlib-1.3.72.jar:3856a7349ebacd6d1be6802b2fed9c4dc2c5a564ea92b6b945ac988243d4b16b',
+        'org.jetbrains.kotlin:kotlin-stdlib-jdk8:1.4.32:kotlin-stdlib-jdk8-1.4.32.jar:adc43e54757b106e0cd7b3b7aa257dff471b61efdabe067fc02b2f57e2396262',
         'org.jetbrains.kotlin:kotlin-stdlib:1.4.20:kotlin-stdlib-1.4.20.jar:b8ab1da5cdc89cb084d41e1f28f20a42bd431538642a5741c52bbfae3fa3e656',
+        'org.jetbrains.kotlin:kotlin-stdlib:1.4.32:kotlin-stdlib-1.4.32.jar:13e9fd3e69dc7230ce0fc873a92a4e5d521d179bcf1bef75a6705baac3bfecba',
         'org.jetbrains.kotlinx:kotlinx-metadata-jvm:0.1.0:kotlinx-metadata-jvm-0.1.0.jar:9753bb39efef35957c5c15df9a3cb769aabf2cdfa74b47afcb7760e5146be3b5',
-        'org.jetbrains.trove4j:trove4j:20160824:trove4j-20160824.jar:1917871c8deb468307a584680c87a44572f5a8b0b98c6d397fc0f5f86596dbe7',
         'org.jetbrains:annotations:13.0:annotations-13.0.jar:ace2a10dc8e2d5fd34925ecac03e4988b2c0f851650c94b8cef49ba1bd111478',
         'org.jmock:jmock-imposters:2.12.0:jmock-imposters-2.12.0.jar:3b836269745a137c9b2347e8d7c2104845b126ef04f012d6bfd94f1a7dea7b09',
         'org.jmock:jmock-junit4:2.12.0:jmock-junit4-2.12.0.jar:3233062fc889637c151a24f1ee086bad04321ab7d8264fef279daff0fa27205b',
         'org.jmock:jmock-legacy:2.12.0:jmock-legacy-2.12.0.jar:dea3a9cca653d082e2fe7e40232e982fe03a9984c7d67ceff24f3e03fe580dcd',
         'org.jmock:jmock-testjar:2.12.0:jmock-testjar-2.12.0.jar:efefbcf6cd294d0e29f0c46eb2a3380d4ca4e1763ff719c69e2f2ac62f564a04',
         'org.jmock:jmock:2.12.0:jmock-2.12.0.jar:266d07314c0cd343c46ff8a55601272de8cf406807caf55e6f313295f83d10be',
-        'org.jvnet.staxex:stax-ex:1.8:stax-ex-1.8.jar:95b05d9590af4154c6513b9c5dc1fb2e55b539972ba0a9ef28e9a0c01d83ad77',
+        'org.junit.jupiter:junit-jupiter-api:5.7.0:junit-jupiter-api-5.7.0.jar:b03f78e0daeed2d77a0af9bcd662b4cdb9693f7ee72e01a539b508b84c63d182',
+        'org.junit.jupiter:junit-jupiter-engine:5.7.0:junit-jupiter-engine-5.7.0.jar:dfa26af94644ac2612dde6625852fcb550a0d21caa243257de54cba738ba87af',
+        'org.junit.platform:junit-platform-commons:1.7.0:junit-platform-commons-1.7.0.jar:5330ee87cc7586e6e25175a34e9251624ff12ff525269d3415d0b4ca519b6fea',
+        'org.junit.platform:junit-platform-engine:1.7.0:junit-platform-engine-1.7.0.jar:75f21a20dc594afdc875736725b408cec6d0344874d29f34b2dd3075500236f2',
+        'org.junit.platform:junit-platform-launcher:1.7.0:junit-platform-launcher-1.7.0.jar:fbdc748fde4c4279fe1d3c607447cb3b7ccd45d7338fc574f8a894ddf2d16818',
+        'org.jvnet.staxex:stax-ex:1.8.1:stax-ex-1.8.1.jar:20522549056e9e50aa35ef0b445a2e47a53d06be0b0a9467d704e2483ffb049a',
         'org.objenesis:objenesis:3.0.1:objenesis-3.0.1.jar:7a8ff780b9ff48415d7c705f60030b0acaa616e7f823c98eede3b63508d4e984',
+        'org.opentest4j:opentest4j:1.2.0:opentest4j-1.2.0.jar:58812de60898d976fb81ef3b62da05c6604c18fd4a249f5044282479fc286af2',
         'org.ow2.asm:asm-analysis:7.0:asm-analysis-7.0.jar:e981f8f650c4d900bb033650b18e122fa6b161eadd5f88978d08751f72ee8474',
         'org.ow2.asm:asm-commons:7.0:asm-commons-7.0.jar:fed348ef05958e3e846a3ac074a12af5f7936ef3d21ce44a62c4fa08a771927d',
         'org.ow2.asm:asm-tree:7.0:asm-tree-7.0.jar:cfd7a0874f9de36a999c127feeadfbfe6e04d4a71ee954d7af3d853f0be48a6c',
         'org.ow2.asm:asm-util:7.0:asm-util-7.0.jar:75fbbca440ef463f41c2b0ab1a80abe67e910ac486da60a7863cbcb5bae7e145',
         'org.ow2.asm:asm:7.0:asm-7.0.jar:b88ef66468b3c978ad0c97fd6e90979e56155b4ac69089ba7a44e9aa7ffe9acf',
         'org.ow2.asm:asm:7.1:asm-7.1.jar:4ab2fa2b6d2cc9ccb1eaa05ea329c407b47b13ed2915f62f8c4b8cc96258d4de',
+        'org.testng:testng:7.3.0:testng-7.3.0.jar:63727488f9717d57f0d0a0fee5a1fc10a2be9cfcff2ec3a7187656d663c0774e',
+        'xerces:xercesImpl:2.12.0:xercesImpl-2.12.0.jar:b50d3a4ca502faa4d1c838acb8aa9480446953421f7327e338c5dda3da5e76d0',
+        'xml-apis:xml-apis:1.4.01:xml-apis-1.4.01.jar:a840968176645684bb01aed376e067ab39614885f9eee44abe35a5f20ebe7fad',
     ]
 }

bramble-api/build.gradle

@@ -9,11 +9,11 @@ apply from: 'witness.gradle'
 dependencies {
 	implementation "com.google.dagger:dagger:$dagger_version"
 	implementation 'com.google.code.findbugs:jsr305:3.0.2'
+	implementation "com.fasterxml.jackson.core:jackson-annotations:$jackson_version"
 
 	testImplementation "junit:junit:$junit_version"
 	testImplementation "org.jmock:jmock:$jmock_version"
 	testImplementation "org.jmock:jmock-junit4:$jmock_version"
-	testImplementation "org.jmock:jmock-legacy:$jmock_version"
 
 	signature 'org.codehaus.mojo.signature:java16:1.1@signature'
 }

bramble-api/src/main/java/org/briarproject/bramble/api/Cancellable.java

@@ -0,0 +1,6 @@
+package org.briarproject.bramble.api;
+
+public interface Cancellable {
+
+	void cancel();
+}

bramble-api/src/main/java/org/briarproject/bramble/api/FeatureFlags.java

@@ -10,4 +10,12 @@ public interface FeatureFlags {
 	boolean shouldEnableProfilePictures();
 
 	boolean shouldEnableDisappearingMessages();
+
+	boolean shouldEnableMailbox();
+
+	boolean shouldEnablePrivateGroupsInCore();
+
+	boolean shouldEnableForumsInCore();
+
+	boolean shouldEnableBlogsInCore();
 }

bramble-api/src/main/java/org/briarproject/bramble/api/StringMap.java

@@ -1,8 +1,14 @@
 package org.briarproject.bramble.api;
 
+import org.briarproject.bramble.util.StringUtils;
+
+import java.util.ArrayList;
 import java.util.Hashtable;
+import java.util.List;
 import java.util.Map;
 
+import javax.annotation.Nullable;
+
 public abstract class StringMap extends Hashtable<String, String> {
 
 	protected StringMap(Map<String, String> m) {
@@ -52,4 +58,31 @@ public abstract class StringMap extends Hashtable<String, String> {
 	public void putLong(String key, long value) {
 		put(key, String.valueOf(value));
 	}
+
+	@Nullable
+	public int[] getIntArray(String key) {
+		String s = get(key);
+		if (s == null) return null;
+		// Handle empty string because "".split(",") returns {""}
+		if (s.length() == 0) return new int[0];
+		String[] intStrings = s.split(",");
+		int[] ints = new int[intStrings.length];
+		try {
+			for (int i = 0; i < ints.length; i++) {
+				ints[i] = Integer.parseInt(intStrings[i]);
+			}
+		} catch (NumberFormatException e) {
+			return null;
+		}
+		return ints;
+	}
+
+	public void putIntArray(String key, int[] value) {
+		List<String> intStrings = new ArrayList<>();
+		for (int integer : value) {
+			intStrings.add(String.valueOf(integer));
+		}
+		// Puts empty string if input array value is empty
+		put(key, StringUtils.join(intStrings, ","));
+	}
 }

bramble-api/src/main/java/org/briarproject/bramble/api/UniqueId.java

@@ -6,14 +6,14 @@ import javax.annotation.concurrent.ThreadSafe;
 
 @ThreadSafe
 @NotNullByDefault
-public abstract class UniqueId extends Bytes {
+public class UniqueId extends Bytes {
 
 	/**
 	 * The length of a unique identifier in bytes.
 	 */
 	public static final int LENGTH = 32;
 
-	protected UniqueId(byte[] id) {
+	public UniqueId(byte[] id) {
 		super(id);
 		if (id.length != LENGTH) throw new IllegalArgumentException();
 	}

bramble-api/src/main/java/org/briarproject/bramble/api/WeakSingletonProvider.java

@@ -0,0 +1,35 @@
+package org.briarproject.bramble.api;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import java.lang.ref.WeakReference;
+
+import javax.annotation.concurrent.GuardedBy;
+import javax.inject.Provider;
+
+/**
+ * A {@link Provider} that keeps a {@link WeakReference} to the last provided
+ * instance and provides the same instance again until the instance is garbage
+ * collected.
+ */
+@NotNullByDefault
+public abstract class WeakSingletonProvider<T> implements Provider<T> {
+
+	private final Object lock = new Object();
+	@GuardedBy("lock")
+	private WeakReference<T> ref = new WeakReference<>(null);
+
+	@Override
+	public T get() {
+		synchronized (lock) {
+			T instance = ref.get();
+			if (instance == null) {
+				instance = createInstance();
+				ref = new WeakReference<>(instance);
+			}
+			return instance;
+		}
+	}
+
+	public abstract T createInstance();
+}

bramble-api/src/main/java/org/briarproject/bramble/api/client/ClientHelper.java

@@ -9,6 +9,8 @@ import org.briarproject.bramble.api.data.BdfList;
 import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.db.Transaction;
 import org.briarproject.bramble.api.identity.Author;
+import org.briarproject.bramble.api.mailbox.MailboxUpdate;
+import org.briarproject.bramble.api.mailbox.MailboxVersion;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.TransportId;
 import org.briarproject.bramble.api.properties.TransportProperties;
@@ -18,6 +20,7 @@ import org.briarproject.bramble.api.sync.MessageId;
 
 import java.security.GeneralSecurityException;
 import java.util.Collection;
+import java.util.List;
 import java.util.Map;
 
 @NotNullByDefault
@@ -123,12 +126,25 @@ public interface ClientHelper {
 	Map<TransportId, TransportProperties> parseAndValidateTransportPropertiesMap(
 			BdfDictionary properties) throws FormatException;
 
+	/**
+	 * Parse and validate the elements of a Mailbox update message.
+	 *
+	 * @return the parsed update message
+	 * @throws FormatException if the message elements are invalid
+	 */
+	MailboxUpdate parseAndValidateMailboxUpdate(BdfList clientSupports,
+			BdfList serverSupports, BdfDictionary properties)
+			throws FormatException;
+
+	List<MailboxVersion> parseMailboxVersionList(BdfList bdfList)
+			throws FormatException;
+
 	/**
 	 * Retrieves the contact ID from the group metadata of the given contact
 	 * group.
 	 */
 	ContactId getContactId(Transaction txn, GroupId contactGroupId)
-			throws DbException, FormatException;
+			throws DbException;
 
 	/**
 	 * Stores the given contact ID in the group metadata of the given contact

bramble-api/src/main/java/org/briarproject/bramble/api/contact/ContactManager.java

@@ -107,6 +107,32 @@ public interface ContactManager {
 	 */
 	String getHandshakeLink() throws DbException;
 
+	/**
+	 * Returns the handshake link that needs to be sent to a contact we want
+	 * to add.
+	 */
+	String getHandshakeLink(Transaction txn) throws DbException;
+
+	/**
+	 * Creates a {@link PendingContact} from the given handshake link and
+	 * alias, adds it to the database and returns it.
+	 *
+	 * @param link The handshake link received from the pending contact
+	 * @param alias The alias the user has given this pending contact
+	 * @throws UnsupportedVersionException If the link uses a format version
+	 * that is not supported
+	 * @throws FormatException If the link is invalid
+	 * @throws GeneralSecurityException If the pending contact's handshake
+	 * public key is invalid
+	 * @throws ContactExistsException If a contact with the same handshake
+	 * public key already exists
+	 * @throws PendingContactExistsException If a pending contact with the same
+	 * handshake public key already exists
+	 */
+	PendingContact addPendingContact(Transaction txn, String link, String alias)
+			throws DbException, FormatException, GeneralSecurityException,
+			ContactExistsException, PendingContactExistsException;
+
 	/**
 	 * Creates a {@link PendingContact} from the given handshake link and
 	 * alias, adds it to the database and returns it.
@@ -140,11 +166,24 @@ public interface ContactManager {
 	Collection<Pair<PendingContact, PendingContactState>> getPendingContacts()
 			throws DbException;
 
+	/**
+	 * Returns a list of {@link PendingContact PendingContacts} and their
+	 * {@link PendingContactState states}.
+	 */
+	Collection<Pair<PendingContact, PendingContactState>> getPendingContacts(Transaction txn)
+			throws DbException;
+
 	/**
 	 * Removes a {@link PendingContact}.
 	 */
 	void removePendingContact(PendingContactId p) throws DbException;
 
+	/**
+	 * Removes a {@link PendingContact}.
+	 */
+	void removePendingContact(Transaction txn, PendingContactId p)
+			throws DbException;
+
 	/**
 	 * Returns the contact with the given ID.
 	 */

bramble-api/src/main/java/org/briarproject/bramble/api/contact/PendingContactId.java

@@ -3,7 +3,6 @@ package org.briarproject.bramble.api.contact;
 import org.briarproject.bramble.api.UniqueId;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 
-import javax.annotation.Nullable;
 import javax.annotation.concurrent.ThreadSafe;
 
 /**
@@ -17,9 +16,4 @@ public class PendingContactId extends UniqueId {
 	public PendingContactId(byte[] id) {
 		super(id);
 	}
-
-	@Override
-	public boolean equals(@Nullable Object o) {
-		return o instanceof PendingContactId && super.equals(o);
-	}
 }

bramble-api/src/main/java/org/briarproject/bramble/api/crypto/CryptoComponent.java

@@ -1,5 +1,6 @@
 package org.briarproject.bramble.api.crypto;
 
+import org.briarproject.bramble.api.UniqueId;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 
 import java.security.GeneralSecurityException;
@@ -10,6 +11,8 @@ import javax.annotation.Nullable;
 @NotNullByDefault
 public interface CryptoComponent {
 
+	UniqueId generateUniqueId();
+
 	SecretKey generateSecretKey();
 
 	SecureRandom getSecureRandom();
@@ -170,4 +173,13 @@ public interface CryptoComponent {
 	 * length. The line terminator is CRLF.
 	 */
 	String asciiArmour(byte[] b, int lineLength);
+
+	/**
+	 * Encode the Onion given its public key. Specified here:
+	 * https://gitweb.torproject.org/torspec.git/tree/rend-spec-v3.txt?id=29245fd5#n2135
+	 *
+	 * @return the encoded onion, base32 chars
+	 */
+	String encodeOnion(byte[] publicKey);
+
 }

bramble-api/src/main/java/org/briarproject/bramble/api/db/DatabaseComponent.java

@@ -33,11 +33,18 @@ import java.util.List;
 import java.util.Map;
 
 import javax.annotation.Nullable;
+import javax.annotation.concurrent.ThreadSafe;
 
 /**
  * Encapsulates the database implementation and exposes high-level operations
  * to other components.
+ * <p>
+ * With the exception of the {@link #open(SecretKey, MigrationListener)} and
+ * {@link #close()} methods, which must not be called concurrently, the
+ * database can be accessed from any thread. See {@link TransactionManager}
+ * for locking behaviour.
  */
+@ThreadSafe
 @NotNullByDefault
 public interface DatabaseComponent extends TransactionManager {
 
@@ -193,26 +200,15 @@ public interface DatabaseComponent extends TransactionManager {
 			throws DbException;
 
 	/**
-	 * Returns a batch of messages for the given contact, with a total length
+	 * Returns a batch of messages for the given contact, for transmission over
-	 * less than or equal to the given length, for transmission over a
+	 * a transport with the given maximum latency. The total length of the
-	 * transport with the given maximum latency. Returns null if there are no
+	 * messages, including record headers, will be no more than the given
-	 * sendable messages that fit in the given length.
+	 * capacity. Returns null if there are no sendable messages that would fit
+	 * in the given capacity.
 	 */
 	@Nullable
 	Collection<Message> generateBatch(Transaction txn, ContactId c,
-			int maxLength, long maxLatency) throws DbException;
+			long capacity, long maxLatency) throws DbException;
-
-	/**
-	 * Returns a batch of messages for the given contact containing the
-	 * messages with the given IDs, for transmission over a transport with
-	 * the given maximum latency.
-	 * <p/>
-	 * If any of the given messages are not in the database or are not visible
-	 * to the contact, they are omitted from the batch without throwing an
-	 * exception.
-	 */
-	Collection<Message> generateBatch(Transaction txn, ContactId c,
-			Collection<MessageId> ids, long maxLatency) throws DbException;
 
 	/**
 	 * Returns an offer for the given contact for transmission over a
@@ -232,15 +228,16 @@ public interface DatabaseComponent extends TransactionManager {
 			throws DbException;
 
 	/**
-	 * Returns a batch of messages for the given contact, with a total length
+	 * Returns a batch of messages for the given contact, for transmission over
-	 * less than or equal to the given length, for transmission over a
+	 * a transport with the given maximum latency. Only messages that have been
-	 * transport with the given maximum latency. Only messages that have been
+	 * requested by the contact are returned. The total length of the messages,
-	 * requested by the contact are returned. Returns null if there are no
+	 * including record headers, will be no more than the given capacity.
-	 * sendable messages that fit in the given length.
+	 * Returns null if there are no sendable messages that have been requested
+	 * by the contact and would fit in the given capacity.
 	 */
 	@Nullable
 	Collection<Message> generateRequestedBatch(Transaction txn, ContactId c,
-			int maxLength, long maxLatency) throws DbException;
+			long capacity, long maxLatency) throws DbException;
 
 	/**
 	 * Returns the contact with the given ID.
@@ -344,6 +341,30 @@ public interface DatabaseComponent extends TransactionManager {
 	Collection<MessageId> getMessageIds(Transaction txn, GroupId g,
 			Metadata query) throws DbException;
 
+	/**
+	 * Returns the IDs of some messages received from the given contact that
+	 * need to be acknowledged, up to the given number of messages.
+	 * <p/>
+	 * Read-only.
+	 */
+	Collection<MessageId> getMessagesToAck(Transaction txn, ContactId c,
+			int maxMessages) throws DbException;
+
+	/**
+	 * Returns the IDs of some messages that are eligible to be sent to the
+	 * given contact over a transport with the given maximum latency. The total
+	 * length of the messages including record headers will be no more than the
+	 * given capacity.
+	 * <p/>
+	 * Unlike {@link #getUnackedMessagesToSend(Transaction, ContactId)} this
+	 * method does not return messages that have already been sent unless they
+	 * are due for retransmission.
+	 * <p/>
+	 * Read-only.
+	 */
+	Collection<MessageId> getMessagesToSend(Transaction txn, ContactId c,
+			long capacity, long maxLatency) throws DbException;
+
 	/**
 	 * Returns the IDs of any messages that need to be validated.
 	 * <p/>
@@ -460,17 +481,40 @@ public interface DatabaseComponent extends TransactionManager {
 	MessageStatus getMessageStatus(Transaction txn, ContactId c, MessageId m)
 			throws DbException;
 
+	/**
+	 * Returns the message with the given ID for transmission to the given
+	 * contact over a transport with the given maximum latency. Returns null
+	 * if the message is no longer visible to the contact.
+	 *
+	 * @param markAsSent True if the message should be marked as sent.
+	 * If false it can be marked as sent by calling
+	 * {@link #setMessagesSent(Transaction, ContactId, Collection, long)}.
+	 */
+	@Nullable
+	Message getMessageToSend(Transaction txn, ContactId c, MessageId m,
+			long maxLatency, boolean markAsSent) throws DbException;
+
 	/**
 	 * Returns the IDs of all messages that are eligible to be sent to the
-	 * given contact, together with their raw lengths. This may include
+	 * given contact.
-	 * messages that have already been sent and are not yet due for
+	 * <p>
-	 * retransmission.
+	 * Unlike {@link #getMessagesToSend(Transaction, ContactId, long, long)}
+	 * this method may return messages that have already been sent and are
+	 * not yet due for retransmission.
 	 * <p/>
 	 * Read-only.
 	 */
-	Map<MessageId, Integer> getUnackedMessagesToSend(Transaction txn,
+	Collection<MessageId> getUnackedMessagesToSend(Transaction txn,
 			ContactId c) throws DbException;
 
+	/**
+	 * Resets the transmission count, expiry time and max latency of all messages
+	 * that are eligible to be sent to the given contact. This includes messages
+	 * that have already been sent and are not yet due for retransmission.
+	 */
+	void resetUnackedMessagesToSend(Transaction txn, ContactId c)
+			throws DbException;
+
 	/**
 	 * Returns the total length, including headers, of all messages that are
 	 * eligible to be sent to the given contact. This may include messages
@@ -640,6 +684,13 @@ public interface DatabaseComponent extends TransactionManager {
 	void removeTransportKeys(Transaction txn, TransportId t, KeySetId k)
 			throws DbException;
 
+	/**
+	 * Records an ack for the given messages as having been sent to the given
+	 * contact.
+	 */
+	void setAckSent(Transaction txn, ContactId c, Collection<MessageId> acked)
+			throws DbException;
+
 	/**
 	 * Sets the cleanup timer duration for the given message. This does not
 	 * start the message's cleanup timer.
@@ -686,6 +737,13 @@ public interface DatabaseComponent extends TransactionManager {
 	void setMessageState(Transaction txn, MessageId m, MessageState state)
 			throws DbException;
 
+	/**
+	 * Records the given messages as having been sent to the given contact
+	 * over a transport with the given maximum latency.
+	 */
+	void setMessagesSent(Transaction txn, ContactId c,
+			Collection<MessageId> sent, long maxLatency) throws DbException;
+
 	/**
 	 * Adds dependencies for a message
 	 */

bramble-api/src/main/java/org/briarproject/bramble/api/db/DatabaseExecutor.java

@@ -18,6 +18,10 @@ import static java.lang.annotation.RetentionPolicy.RUNTIME;
  * submitted, tasks are not run concurrently, and submitting a task will never
  * block. Tasks must not run indefinitely. Tasks submitted during shutdown are
  * discarded.
+ * <p>
+ * It is not mandatory to use this executor for database tasks. The database
+ * can be accessed from any thread, but this executor's guarantee that tasks
+ * are run in the order they're submitted may be useful in some cases.
  */
 @Qualifier
 @Target({FIELD, METHOD, PARAMETER})

bramble-api/src/main/java/org/briarproject/bramble/api/db/Transaction.java

@@ -45,6 +45,9 @@ public class Transaction {
 	/**
 	 * Attaches an event to be broadcast when the transaction has been
 	 * committed. The event will be broadcast on the {@link EventExecutor}.
+	 * Events and {@link #attach(Runnable) tasks} are submitted to the
+	 * {@link EventExecutor} in the order they were attached to the
+	 * transaction.
 	 */
 	public void attach(Event e) {
 		if (actions == null) actions = new ArrayList<>();
@@ -54,6 +57,9 @@ public class Transaction {
 	/**
 	 * Attaches a task to be executed when the transaction has been
 	 * committed. The task will be run on the {@link EventExecutor}.
+	 * {@link #attach(Event) Events} and tasks are submitted to the
+	 * {@link EventExecutor} in the order they were attached to the
+	 * transaction.
 	 */
 	public void attach(Runnable r) {
 		if (actions == null) actions = new ArrayList<>();

bramble-api/src/main/java/org/briarproject/bramble/api/db/TransactionManager.java

@@ -1,51 +1,95 @@
 package org.briarproject.bramble.api.db;
 
+import org.briarproject.bramble.api.event.EventExecutor;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 
 import javax.annotation.Nullable;
+import javax.annotation.concurrent.ThreadSafe;
 
+/**
+ * An interface for managing database transactions.
+ * <p>
+ * Read-only transactions may access the database concurrently. Read-write
+ * transactions access the database exclusively, so starting a read-only or
+ * read-write transaction will block until there are no read-write
+ * transactions in progress.
+ * <p>
+ * Failing to {@link #endTransaction(Transaction) end} a transaction will
+ * prevent other callers from accessing the database, so it is recommended to
+ * use the {@link #transaction(boolean, DbRunnable)},
+ * {@link #transactionWithResult(boolean, DbCallable)} and
+ * {@link #transactionWithNullableResult(boolean, NullableDbCallable)} methods
+ * where possible, which handle committing or aborting the transaction on the
+ * caller's behalf.
+ * <p>
+ * Transactions are not reentrant, i.e. it is not permitted to start a
+ * transaction on a thread that already has a transaction in progress.
+ */
+@ThreadSafe
 @NotNullByDefault
 public interface TransactionManager {
 
 	/**
-	 * Starts a new transaction and returns an object representing it.
+	 * Starts a new transaction and returns an object representing it. This
-	 * <p/>
+	 * method acquires the database lock, which is held until
-	 * This method acquires locks, so it must not be called while holding a
+	 * {@link #endTransaction(Transaction)} is called.
-	 * lock.
 	 *
-	 * @param readOnly true if the transaction will only be used for reading.
+	 * @param readOnly True if the transaction will only be used for reading,
+	 * in which case the database lock can be shared with other read-only
+	 * transactions.
 	 */
 	Transaction startTransaction(boolean readOnly) throws DbException;
 
 	/**
 	 * Commits a transaction to the database.
+	 * {@link #endTransaction(Transaction)} must be called to release the
+	 * database lock.
 	 */
 	void commitTransaction(Transaction txn) throws DbException;
 
 	/**
-	 * Ends a transaction. If the transaction has not been committed,
+	 * Ends a transaction. If the transaction has not been committed by
-	 * it will be aborted. If the transaction has been committed,
+	 * calling {@link #commitTransaction(Transaction)}, it is aborted and the
-	 * any events attached to the transaction are broadcast.
+	 * database lock is released.
-	 * The database lock will be released in either case.
+	 * <p>
+	 * If the transaction has been committed, any
+	 * {@link Transaction#attach events} attached to the transaction are
+	 * broadcast and any {@link Transaction#attach(Runnable) tasks} attached
+	 * to the transaction are submitted to the {@link EventExecutor}. The
+	 * database lock is then released.
 	 */
 	void endTransaction(Transaction txn);
 
 	/**
-	 * Runs the given task within a transaction.
+	 * Runs the given task within a transaction. The database lock is held
+	 * while running the task.
+	 *
+	 * @param readOnly True if the transaction will only be used for reading,
+	 * in which case the database lock can be shared with other read-only
+	 * transactions.
 	 */
 	<E extends Exception> void transaction(boolean readOnly,
 			DbRunnable<E> task) throws DbException, E;
 
 	/**
 	 * Runs the given task within a transaction and returns the result of the
-	 * task.
+	 * task. The database lock is held while running the task.
+	 *
+	 * @param readOnly True if the transaction will only be used for reading,
+	 * in which case the database lock can be shared with other read-only
+	 * transactions.
 	 */
 	<R, E extends Exception> R transactionWithResult(boolean readOnly,
 			DbCallable<R, E> task) throws DbException, E;
 
 	/**
 	 * Runs the given task within a transaction and returns the result of the
-	 * task, which may be null.
+	 * task, which may be null. The database lock is held while running the
+	 * task.
+	 *
+	 * @param readOnly True if the transaction will only be used for reading,
+	 * in which case the database lock can be shared with other read-only
+	 * transactions.
 	 */
 	@Nullable
 	<R, E extends Exception> R transactionWithNullableResult(boolean readOnly,

bramble-api/src/main/java/org/briarproject/bramble/api/identity/AuthorId.java

@@ -21,9 +21,4 @@ public class AuthorId extends UniqueId {
 	public AuthorId(byte[] id) {
 		super(id);
 	}
-
-	@Override
-	public boolean equals(Object o) {
-		return o instanceof AuthorId && super.equals(o);
-	}
 }

bramble-api/src/main/java/org/briarproject/bramble/api/mailbox/InvalidMailboxIdException.java

@@ -0,0 +1,8 @@
+package org.briarproject.bramble.api.mailbox;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+@NotNullByDefault
+public class InvalidMailboxIdException extends Exception {
+
+}

bramble-api/src/main/java/org/briarproject/bramble/api/mailbox/MailboxAuthToken.java

@@ -0,0 +1,24 @@
+package org.briarproject.bramble.api.mailbox;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import javax.annotation.Nullable;
+import javax.annotation.concurrent.ThreadSafe;
+
+@ThreadSafe
+@NotNullByDefault
+public class MailboxAuthToken extends MailboxId {
+	public MailboxAuthToken(byte[] id) {
+		super(id);
+	}
+
+	/**
+	 * Creates a {@link MailboxAuthToken} from the given string.
+	 *
+	 * @throws InvalidMailboxIdException if token is not valid.
+	 */
+	public static MailboxAuthToken fromString(@Nullable String token)
+			throws InvalidMailboxIdException {
+		return new MailboxAuthToken(bytesFromString(token));
+	}
+}

bramble-api/src/main/java/org/briarproject/bramble/api/mailbox/MailboxConstants.java

@@ -0,0 +1,37 @@
+package org.briarproject.bramble.api.mailbox;
+
+import static java.util.concurrent.TimeUnit.HOURS;
+import static org.briarproject.bramble.api.transport.TransportConstants.MAX_FRAME_LENGTH;
+import static org.briarproject.bramble.api.transport.TransportConstants.MAX_PAYLOAD_LENGTH;
+import static org.briarproject.bramble.api.transport.TransportConstants.STREAM_HEADER_LENGTH;
+import static org.briarproject.bramble.api.transport.TransportConstants.TAG_LENGTH;
+
+public interface MailboxConstants {
+
+	/**
+	 * The maximum length of a file that can be uploaded to or downloaded from
+	 * a mailbox.
+	 */
+	int MAX_FILE_BYTES = 1024 * 1024;
+
+	/**
+	 * The maximum length of the plaintext payload of a file, such that the
+	 * ciphertext is no more than {@link #MAX_FILE_BYTES}.
+	 */
+	int MAX_FILE_PAYLOAD_BYTES =
+			(MAX_FILE_BYTES - TAG_LENGTH - STREAM_HEADER_LENGTH)
+					/ MAX_FRAME_LENGTH * MAX_PAYLOAD_LENGTH;
+
+	/**
+	 * The number of connection failures
+	 * that indicate a problem with the mailbox.
+	 */
+	int PROBLEM_NUM_CONNECTION_FAILURES = 5;
+
+	/**
+	 * The time in milliseconds since the last connection success
+	 * that need to pass to indicates a problem with the mailbox.
+	 */
+	long PROBLEM_MS_SINCE_LAST_SUCCESS = HOURS.toMillis(1);
+
+}

bramble-api/src/main/java/org/briarproject/bramble/api/mailbox/MailboxFileId.java

@@ -0,0 +1,24 @@
+package org.briarproject.bramble.api.mailbox;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import javax.annotation.Nullable;
+import javax.annotation.concurrent.ThreadSafe;
+
+@ThreadSafe
+@NotNullByDefault
+public class MailboxFileId extends MailboxId {
+	public MailboxFileId(byte[] id) {
+		super(id);
+	}
+
+	/**
+	 * Creates a {@link MailboxFileId} from the given string.
+	 *
+	 * @throws IllegalArgumentException if token is not valid.
+	 */
+	public static MailboxFileId fromString(@Nullable String token)
+			throws InvalidMailboxIdException {
+		return new MailboxFileId(bytesFromString(token));
+	}
+}

bramble-api/src/main/java/org/briarproject/bramble/api/mailbox/MailboxFolderId.java

@@ -0,0 +1,24 @@
+package org.briarproject.bramble.api.mailbox;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import javax.annotation.Nullable;
+import javax.annotation.concurrent.ThreadSafe;
+
+@ThreadSafe
+@NotNullByDefault
+public class MailboxFolderId extends MailboxId {
+	public MailboxFolderId(byte[] id) {
+		super(id);
+	}
+
+	/**
+	 * Creates a {@link MailboxFolderId} from the given string.
+	 *
+	 * @throws IllegalArgumentException if token is not valid.
+	 */
+	public static MailboxFolderId fromString(@Nullable String token)
+			throws InvalidMailboxIdException {
+		return new MailboxFolderId(bytesFromString(token));
+	}
+}

bramble-api/src/main/java/org/briarproject/bramble/api/mailbox/MailboxId.java

@@ -0,0 +1,49 @@
+package org.briarproject.bramble.api.mailbox;
+
+import com.fasterxml.jackson.annotation.JsonValue;
+
+import org.briarproject.bramble.api.UniqueId;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import java.util.Locale;
+
+import javax.annotation.Nullable;
+import javax.annotation.concurrent.ThreadSafe;
+
+import static org.briarproject.bramble.util.StringUtils.fromHexString;
+import static org.briarproject.bramble.util.StringUtils.toHexString;
+
+@ThreadSafe
+@NotNullByDefault
+public abstract class MailboxId extends UniqueId {
+	MailboxId(byte[] id) {
+		super(id);
+	}
+
+	/**
+	 * Returns valid {@link MailboxId} bytes from the given string.
+	 *
+	 * @throws InvalidMailboxIdException if token is not valid.
+	 */
+	static byte[] bytesFromString(@Nullable String token)
+			throws InvalidMailboxIdException {
+		if (token == null || token.length() != 64) {
+			throw new InvalidMailboxIdException();
+		}
+		try {
+			return fromHexString(token);
+		} catch (IllegalArgumentException e) {
+			throw new InvalidMailboxIdException();
+		}
+	}
+
+	/**
+	 * Returns the string representation expected by the mailbox API.
+	 * Also used for serialization.
+	 */
+	@Override
+	@JsonValue
+	public String toString() {
+		return toHexString(getBytes()).toLowerCase(Locale.US);
+	}
+}

bramble-api/src/main/java/org/briarproject/bramble/api/mailbox/MailboxManager.java

@@ -0,0 +1,56 @@
+package org.briarproject.bramble.api.mailbox;
+
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.db.Transaction;
+import org.briarproject.bramble.api.lifecycle.IoExecutor;
+import org.briarproject.bramble.api.mailbox.event.OwnMailboxConnectionStatusEvent;
+
+import javax.annotation.Nullable;
+
+public interface MailboxManager {
+
+	/**
+	 * @return true if a mailbox is already paired.
+	 */
+	boolean isPaired(Transaction txn) throws DbException;
+
+	/**
+	 * @return the current status of the mailbox.
+	 */
+	MailboxStatus getMailboxStatus(Transaction txn) throws DbException;
+
+	/**
+	 * Returns the currently running pairing task,
+	 * or null if no pairing task is running.
+	 */
+	@Nullable
+	MailboxPairingTask getCurrentPairingTask();
+
+	/**
+	 * Starts and returns a pairing task. If a pairing task is already running,
+	 * it will be returned and the argument will be ignored.
+	 *
+	 * @param qrCodePayload The ISO-8859-1 encoded bytes of the mailbox QR code.
+	 */
+	MailboxPairingTask startPairingTask(String qrCodePayload);
+
+	/**
+	 * Can be used by the UI to test the mailbox connection.
+	 *
+	 * @return true (success) or false (error).
+	 * A {@link OwnMailboxConnectionStatusEvent} might be broadcast with a new
+	 * {@link MailboxStatus}.
+	 */
+	boolean checkConnection();
+
+	/**
+	 * Unpairs the owner's mailbox and tries to wipe it.
+	 * As this makes a network call, it should be run on the {@link IoExecutor}.
+	 *
+	 * @return true if we could wipe the mailbox, false if we couldn't.
+	 * It is advised to inform the user to wipe the mailbox themselves,
+	 * if we failed to wipe it.
+	 */
+	@IoExecutor
+	boolean unPair() throws DbException;
+}

bramble-api/src/main/java/org/briarproject/bramble/api/mailbox/MailboxPairingState.java

@@ -0,0 +1,25 @@
+package org.briarproject.bramble.api.mailbox;
+
+public abstract class MailboxPairingState {
+
+	public static class QrCodeReceived extends MailboxPairingState {
+	}
+
+	public static class Pairing extends MailboxPairingState {
+	}
+
+	public static class Paired extends MailboxPairingState {
+	}
+
+	public static class InvalidQrCode extends MailboxPairingState {
+	}
+
+	public static class MailboxAlreadyPaired extends MailboxPairingState {
+	}
+
+	public static class ConnectionError extends MailboxPairingState {
+	}
+
+	public static class UnexpectedError extends MailboxPairingState {
+	}
+}

bramble-api/src/main/java/org/briarproject/bramble/api/mailbox/MailboxPairingTask.java

@@ -0,0 +1,21 @@
+package org.briarproject.bramble.api.mailbox;
+
+import org.briarproject.bramble.api.Consumer;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+@NotNullByDefault
+public interface MailboxPairingTask extends Runnable {
+
+	/**
+	 * Adds an observer to the task. The observer will be notified on the
+	 * event thread of the current state of the task and any subsequent state
+	 * changes.
+	 */
+	void addObserver(Consumer<MailboxPairingState> observer);
+
+	/**
+	 * Removes an observer from the task.
+	 */
+	void removeObserver(Consumer<MailboxPairingState> observer);
+
+}

bramble-api/src/main/java/org/briarproject/bramble/api/mailbox/MailboxProperties.java

@@ -0,0 +1,80 @@
+package org.briarproject.bramble.api.mailbox;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import java.util.List;
+
+import javax.annotation.Nullable;
+import javax.annotation.concurrent.Immutable;
+
+@Immutable
+@NotNullByDefault
+public class MailboxProperties {
+
+	private final String baseUrl;
+	private final MailboxAuthToken authToken;
+	private final boolean owner;
+	private final List<MailboxVersion> serverSupports;
+	@Nullable
+	private final MailboxFolderId inboxId; // Null for own mailbox
+	@Nullable
+	private final MailboxFolderId outboxId; // Null for own mailbox
+
+	/**
+	 * Constructor for properties used by the mailbox's owner.
+	 */
+	public MailboxProperties(String baseUrl, MailboxAuthToken authToken,
+			List<MailboxVersion> serverSupports) {
+		this.baseUrl = baseUrl;
+		this.authToken = authToken;
+		this.owner = true;
+		this.serverSupports = serverSupports;
+		this.inboxId = null;
+		this.outboxId = null;
+	}
+
+	/**
+	 * Constructor for properties used by a contact of the mailbox's owner.
+	 */
+	public MailboxProperties(String baseUrl, MailboxAuthToken authToken,
+			List<MailboxVersion> serverSupports, MailboxFolderId inboxId,
+			MailboxFolderId outboxId) {
+		this.baseUrl = baseUrl;
+		this.authToken = authToken;
+		this.owner = false;
+		this.serverSupports = serverSupports;
+		this.inboxId = inboxId;
+		this.outboxId = outboxId;
+	}
+
+	public String getBaseUrl() {
+		return baseUrl;
+	}
+
+	public String getOnion() {
+		return baseUrl.replaceFirst("^http://", "")
+				.replaceFirst("\\.onion$", "");
+	}
+
+	public MailboxAuthToken getAuthToken() {
+		return authToken;
+	}
+
+	public boolean isOwner() {
+		return owner;
+	}
+
+	public List<MailboxVersion> getServerSupports() {
+		return serverSupports;
+	}
+
+	@Nullable
+	public MailboxFolderId getInboxId() {
+		return inboxId;
+	}
+
+	@Nullable
+	public MailboxFolderId getOutboxId() {
+		return outboxId;
+	}
+}

bramble-api/src/main/java/org/briarproject/bramble/api/mailbox/MailboxSettingsManager.java

@@ -0,0 +1,65 @@
+package org.briarproject.bramble.api.mailbox;
+
+import org.briarproject.bramble.api.contact.ContactId;
+import org.briarproject.bramble.api.crypto.SecretKey;
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.db.Transaction;
+import org.briarproject.bramble.api.lifecycle.LifecycleManager;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import java.util.List;
+
+import javax.annotation.Nullable;
+
+@NotNullByDefault
+public interface MailboxSettingsManager {
+
+	/**
+	 * Registers a hook to be called when a mailbox has been paired or unpaired.
+	 * This method should be called before
+	 * {@link LifecycleManager#startServices(SecretKey)}.
+	 */
+	void registerMailboxHook(MailboxHook hook);
+
+	@Nullable
+	MailboxProperties getOwnMailboxProperties(Transaction txn)
+			throws DbException;
+
+	void setOwnMailboxProperties(Transaction txn, MailboxProperties p)
+			throws DbException;
+
+	void removeOwnMailboxProperties(Transaction txn) throws DbException;
+
+	MailboxStatus getOwnMailboxStatus(Transaction txn) throws DbException;
+
+	void recordSuccessfulConnection(Transaction txn, long now)
+			throws DbException;
+
+	void recordFailedConnectionAttempt(Transaction txn, long now)
+			throws DbException;
+
+	void setPendingUpload(Transaction txn, ContactId id,
+			@Nullable String filename) throws DbException;
+
+	@Nullable
+	String getPendingUpload(Transaction txn, ContactId id) throws DbException;
+
+	interface MailboxHook {
+		/**
+		 * Called when Briar is paired with a mailbox
+		 *
+		 * @param txn A read-write transaction
+		 * @param ownOnion Our new mailbox's onion (56 base32 chars)
+		 */
+		void mailboxPaired(Transaction txn, String ownOnion,
+				List<MailboxVersion> serverSupports)
+				throws DbException;
+
+		/**
+		 * Called when the mailbox is unpaired
+		 *
+		 * @param txn A read-write transaction
+		 */
+		void mailboxUnpaired(Transaction txn) throws DbException;
+	}
+}

bramble-api/src/main/java/org/briarproject/bramble/api/mailbox/MailboxStatus.java

@@ -0,0 +1,70 @@
+package org.briarproject.bramble.api.mailbox;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import javax.annotation.concurrent.Immutable;
+
+import static org.briarproject.bramble.api.mailbox.MailboxConstants.PROBLEM_MS_SINCE_LAST_SUCCESS;
+import static org.briarproject.bramble.api.mailbox.MailboxConstants.PROBLEM_NUM_CONNECTION_FAILURES;
+
+@Immutable
+@NotNullByDefault
+public class MailboxStatus {
+
+	private final long lastAttempt, lastSuccess;
+	private final int attemptsSinceSuccess;
+
+	public MailboxStatus(long lastAttempt, long lastSuccess,
+			int attemptsSinceSuccess) {
+		this.lastAttempt = lastAttempt;
+		this.lastSuccess = lastSuccess;
+		this.attemptsSinceSuccess = attemptsSinceSuccess;
+	}
+
+	/**
+	 * Returns the time of the last attempt to connect to the mailbox, in
+	 * milliseconds since the Unix epoch, or -1 if no attempt has been made.
+	 * <p>
+	 * If an attempt is in progress and has not yet succeeded or failed then
+	 * this method returns the time of the previous attempt, or -1 if the
+	 * current attempt is the first.
+	 */
+	public long getTimeOfLastAttempt() {
+		return lastAttempt;
+	}
+
+	/**
+	 * Returns the time of the last successful attempt to connect to the
+	 * mailbox, in milliseconds since the Unix epoch, or -1 if no attempt has
+	 * succeeded.
+	 * <p>
+	 * If the last attempt was successful then this method returns the same
+	 * value as {@link #getTimeOfLastAttempt()}. If an attempt is in progress
+	 * and has not yet succeeded or failed then this method returns the time
+	 * of the previous successful connection, or -1 if no attempt has
+	 * succeeded.
+	 */
+	public long getTimeOfLastSuccess() {
+		return lastSuccess;
+	}
+
+	/**
+	 * Returns the number of attempts to connect to the mailbox that have
+	 * failed since the last attempt succeeded, or the number of attempts that
+	 * have been made, if no attempt has ever succeeded.
+	 * <p>
+	 * If an attempt is in progress and has not yet succeeded or failed then
+	 * it is not included in this count.
+	 */
+	public int getAttemptsSinceSuccess() {
+		return attemptsSinceSuccess;
+	}
+
+	/**
+	 * @return true if this status indicates a problem with the mailbox.
+	 */
+	public boolean hasProblem(long now) {
+		return attemptsSinceSuccess >= PROBLEM_NUM_CONNECTION_FAILURES &&
+				(now - lastSuccess) >= PROBLEM_MS_SINCE_LAST_SUCCESS;
+	}
+}

bramble-api/src/main/java/org/briarproject/bramble/api/mailbox/MailboxUpdate.java

@@ -0,0 +1,31 @@
+package org.briarproject.bramble.api.mailbox;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import java.util.List;
+
+import javax.annotation.concurrent.Immutable;
+
+@Immutable
+@NotNullByDefault
+public class MailboxUpdate {
+	private final boolean hasMailbox;
+	private final List<MailboxVersion> clientSupports;
+
+	public MailboxUpdate(List<MailboxVersion> clientSupports) {
+		this(clientSupports, false);
+	}
+
+	MailboxUpdate(List<MailboxVersion> clientSupports, boolean hasMailbox) {
+		this.clientSupports = clientSupports;
+		this.hasMailbox = hasMailbox;
+	}
+
+	public List<MailboxVersion> getClientSupports() {
+		return clientSupports;
+	}
+
+	public boolean hasMailbox() {
+		return hasMailbox;
+	}
+}

bramble-api/src/main/java/org/briarproject/bramble/api/mailbox/MailboxUpdateManager.java

@@ -0,0 +1,72 @@
+package org.briarproject.bramble.api.mailbox;
+
+import org.briarproject.bramble.api.contact.ContactId;
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.db.Transaction;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.sync.ClientId;
+
+import javax.annotation.Nullable;
+
+@NotNullByDefault
+public interface MailboxUpdateManager {
+
+	/**
+	 * The unique ID of the mailbox update (properties) client.
+	 */
+	ClientId CLIENT_ID =
+			new ClientId("org.briarproject.bramble.mailbox.properties");
+
+	/**
+	 * The current major version of the mailbox update (properties) client.
+	 */
+	int MAJOR_VERSION = 2;
+
+	/**
+	 * The current minor version of the mailbox update (properties) client.
+	 */
+	int MINOR_VERSION = 0;
+
+	/**
+	 * The number of properties required for an update message with a mailbox.
+	 */
+	int PROP_COUNT = 4;
+
+	/**
+	 * The required properties of an update message with a mailbox.
+	 */
+	String PROP_KEY_ONION = "onion";
+	String PROP_KEY_AUTHTOKEN = "authToken";
+	String PROP_KEY_INBOXID = "inboxId";
+	String PROP_KEY_OUTBOXID = "outboxId";
+
+	/**
+	 * Length of the Onion property.
+	 */
+	int PROP_ONION_LENGTH = 56;
+
+	/**
+	 * Message metadata key for the version number of a local or remote update,
+	 * as a BDF long.
+	 */
+	String MSG_KEY_VERSION = "version";
+
+	/**
+	 * Message metadata key for whether an update is local or remote, as a BDF
+	 * boolean.
+	 */
+	String MSG_KEY_LOCAL = "local";
+
+	/**
+	 * Key in the client's local group for storing the clientSupports list that
+	 * was last sent out.
+	 */
+	String GROUP_KEY_SENT_CLIENT_SUPPORTS = "sentClientSupports";
+
+	MailboxUpdate getLocalUpdate(Transaction txn, ContactId c)
+			throws DbException;
+
+	@Nullable
+	MailboxUpdate getRemoteUpdate(Transaction txn, ContactId c)
+			throws DbException;
+}

bramble-api/src/main/java/org/briarproject/bramble/api/mailbox/MailboxUpdateWithMailbox.java

@@ -0,0 +1,30 @@
+package org.briarproject.bramble.api.mailbox;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import java.util.List;
+
+import javax.annotation.concurrent.Immutable;
+
+@Immutable
+@NotNullByDefault
+public class MailboxUpdateWithMailbox extends MailboxUpdate {
+
+	private final MailboxProperties properties;
+
+	public MailboxUpdateWithMailbox(List<MailboxVersion> clientSupports,
+			MailboxProperties properties) {
+		super(clientSupports, true);
+		if (properties.isOwner()) throw new IllegalArgumentException();
+		this.properties = properties;
+	}
+
+	public MailboxUpdateWithMailbox(MailboxUpdateWithMailbox o,
+			List<MailboxVersion> newClientSupports) {
+		this(newClientSupports, o.getMailboxProperties());
+	}
+
+	public MailboxProperties getMailboxProperties() {
+		return properties;
+	}
+}

bramble-api/src/main/java/org/briarproject/bramble/api/mailbox/MailboxVersion.java

@@ -0,0 +1,44 @@
+package org.briarproject.bramble.api.mailbox;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import javax.annotation.concurrent.Immutable;
+
+@Immutable
+@NotNullByDefault
+public class MailboxVersion implements Comparable<MailboxVersion> {
+
+	private final int major;
+	private final int minor;
+
+	public MailboxVersion(int major, int minor) {
+		this.major = major;
+		this.minor = minor;
+	}
+
+	public int getMajor() {
+		return major;
+	}
+
+	public int getMinor() {
+		return minor;
+	}
+
+	@Override
+	public boolean equals(Object o) {
+		if (o instanceof MailboxVersion) {
+			MailboxVersion v = (MailboxVersion) o;
+			return major == v.major && minor == v.minor;
+		}
+		return false;
+	}
+
+	@Override
+	public int compareTo(MailboxVersion v) {
+		int c = major - v.major;
+		if (c != 0) {
+			return c;
+		}
+		return minor - v.minor;
+	}
+}

bramble-api/src/main/java/org/briarproject/bramble/api/mailbox/event/MailboxProblemEvent.java

@@ -0,0 +1,19 @@
+package org.briarproject.bramble.api.mailbox.event;
+
+import org.briarproject.bramble.api.event.Event;
+import org.briarproject.bramble.api.mailbox.MailboxSettingsManager;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import javax.annotation.concurrent.Immutable;
+
+/**
+ * An event that is broadcast by {@link MailboxSettingsManager} when
+ * recording a connection failure for own Mailbox
+ * that has persistent for long enough for the mailbox owner to become active
+ * and fix the problem with the mailbox.
+ */
+@Immutable
+@NotNullByDefault
+public class MailboxProblemEvent extends Event {
+
+}

bramble-api/src/main/java/org/briarproject/bramble/api/mailbox/event/OwnMailboxConnectionStatusEvent.java

@@ -0,0 +1,27 @@
+package org.briarproject.bramble.api.mailbox.event;
+
+import org.briarproject.bramble.api.event.Event;
+import org.briarproject.bramble.api.mailbox.MailboxSettingsManager;
+import org.briarproject.bramble.api.mailbox.MailboxStatus;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import javax.annotation.concurrent.Immutable;
+
+/**
+ * An event that is broadcast by {@link MailboxSettingsManager} when
+ * recording the connection status of own Mailbox.
+ */
+@Immutable
+@NotNullByDefault
+public class OwnMailboxConnectionStatusEvent extends Event {
+
+	private final MailboxStatus status;
+
+	public OwnMailboxConnectionStatusEvent(MailboxStatus status) {
+		this.status = status;
+	}
+
+	public MailboxStatus getStatus() {
+		return status;
+	}
+}

bramble-api/src/main/java/org/briarproject/bramble/api/mailbox/event/RemoteMailboxUpdateEvent.java

@@ -0,0 +1,34 @@
+package org.briarproject.bramble.api.mailbox.event;
+
+import org.briarproject.bramble.api.contact.ContactId;
+import org.briarproject.bramble.api.event.Event;
+import org.briarproject.bramble.api.mailbox.MailboxUpdate;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import javax.annotation.concurrent.Immutable;
+
+/**
+ * An event that is broadcast when {@link MailboxUpdate} are received
+ * from a contact.
+ */
+@Immutable
+@NotNullByDefault
+public class RemoteMailboxUpdateEvent extends Event {
+
+	private final ContactId contactId;
+	private final MailboxUpdate mailboxUpdate;
+
+	public RemoteMailboxUpdateEvent(ContactId contactId,
+			MailboxUpdate mailboxUpdate) {
+		this.contactId = contactId;
+		this.mailboxUpdate = mailboxUpdate;
+	}
+
+	public ContactId getContact() {
+		return contactId;
+	}
+
+	public MailboxUpdate getMailboxUpdate() {
+		return mailboxUpdate;
+	}
+}

bramble-api/src/main/java/org/briarproject/bramble/api/plugin/TorConstants.java

@@ -1,34 +1,27 @@
 package org.briarproject.bramble.api.plugin;
 
-import static java.util.concurrent.TimeUnit.DAYS;
+import static java.util.concurrent.TimeUnit.SECONDS;
 
 public interface TorConstants {
 
 	TransportId ID = new TransportId("org.briarproject.bramble.tor");
 
 	// Transport properties
-	String PROP_ONION_V2 = "onion";
 	String PROP_ONION_V3 = "onion3";
 
 	int DEFAULT_SOCKS_PORT = 59050;
 	int DEFAULT_CONTROL_PORT = 59051;
 
-	int CONNECT_TO_PROXY_TIMEOUT = 5000; // Milliseconds
+	int CONNECT_TO_PROXY_TIMEOUT = (int) SECONDS.toMillis(5);
-	int EXTRA_SOCKET_TIMEOUT = 30000; // Milliseconds
+	int EXTRA_CONNECT_TIMEOUT = (int) SECONDS.toMillis(120);
+	int EXTRA_SOCKET_TIMEOUT = (int) SECONDS.toMillis(30);
 
 	// Local settings (not shared with contacts)
 	String PREF_TOR_NETWORK = "network2";
 	String PREF_TOR_PORT = "port";
 	String PREF_TOR_MOBILE = "useMobileData";
 	String PREF_TOR_ONLY_WHEN_CHARGING = "onlyWhenCharging";
-	String HS_PRIVATE_KEY_V2 = "onionPrivKey";
 	String HS_PRIVATE_KEY_V3 = "onionPrivKey3";
-	String HS_V3_CREATED = "onionPrivKey3Created";
-
-	/**
-	 * How long to publish a v3 hidden service before retiring the v2 service.
-	 */
-	long V3_MIGRATION_PERIOD_MS = DAYS.toMillis(180);
 
 	// Values for PREF_TOR_NETWORK
 	int PREF_TOR_NETWORK_AUTOMATIC = 0;

bramble-api/src/main/java/org/briarproject/bramble/api/record/RecordWriter.java

@@ -12,4 +12,6 @@ public interface RecordWriter {
 	void flush() throws IOException;
 
 	void close() throws IOException;
+
+	long getBytesWritten();
 }

bramble-api/src/main/java/org/briarproject/bramble/api/settings/SettingsManager.java

@@ -22,4 +22,11 @@ public interface SettingsManager {
 	 * namespace.
 	 */
 	void mergeSettings(Settings s, String namespace) throws DbException;
+
+	/**
+	 * Merges the given settings with any existing settings in the given
+	 * namespace.
+	 */
+	void mergeSettings(Transaction txn, Settings s, String namespace)
+			throws DbException;
 }

bramble-api/src/main/java/org/briarproject/bramble/api/sync/DeferredSendHandler.java

@@ -0,0 +1,15 @@
+package org.briarproject.bramble.api.sync;
+
+import java.util.Collection;
+
+/**
+ * An interface for holding the IDs of messages sent and acked during an
+ * outgoing {@link SyncSession} so they can be recorded in the DB as sent
+ * or acked at some later time.
+ */
+public interface DeferredSendHandler {
+
+	void onAckSent(Collection<MessageId> acked);
+
+	void onMessageSent(MessageId sent);
+}

bramble-api/src/main/java/org/briarproject/bramble/api/sync/GroupId.java

@@ -20,9 +20,4 @@ public class GroupId extends UniqueId {
 	public GroupId(byte[] id) {
 		super(id);
 	}
-
-	@Override
-	public boolean equals(Object o) {
-		return o instanceof GroupId && super.equals(o);
-	}
 }

bramble-api/src/main/java/org/briarproject/bramble/api/sync/MessageId.java

@@ -27,9 +27,4 @@ public class MessageId extends UniqueId {
 	public MessageId(byte[] id) {
 		super(id);
 	}
-
-	@Override
-	public boolean equals(Object o) {
-		return o instanceof MessageId && super.equals(o);
-	}
 }

bramble-api/src/main/java/org/briarproject/bramble/api/sync/SyncRecordWriter.java

@@ -20,4 +20,6 @@ public interface SyncRecordWriter {
 	void writePriority(Priority p) throws IOException;
 
 	void flush() throws IOException;
+
+	long getBytesWritten();
 }

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

@@ -1,5 +1,6 @@
 package org.briarproject.bramble.api.system;
 
+import org.briarproject.bramble.api.Cancellable;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 
 import java.util.concurrent.Executor;
@@ -16,6 +17,8 @@ public interface TaskScheduler {
 	 * <p>
 	 * If the platform supports wake locks, a wake lock will be held while
 	 * submitting and running the task.
+	 *
+	 * @return A {@link Cancellable} for cancelling the task.
 	 */
 	Cancellable schedule(Runnable task, Executor executor, long delay,
 			TimeUnit unit);
@@ -27,17 +30,11 @@ public interface TaskScheduler {
 	 * <p>
 	 * If the platform supports wake locks, a wake lock will be held while
 	 * submitting and running the task.
+	 *
+	 * @return A {@link Cancellable} for cancelling all future executions of
+	 * the task.
 	 */
 	Cancellable scheduleWithFixedDelay(Runnable task, Executor executor,
 			long delay, long interval, TimeUnit unit);
 
-	interface Cancellable {
-
-		/**
-		 * Cancels the task if it has not already started running. If the task
-		 * is {@link #scheduleWithFixedDelay(Runnable, Executor, long, long, TimeUnit) periodic},
-		 * all future executions of the task are cancelled.
-		 */
-		void cancel();
-	}
 }

bramble-api/src/main/java/org/briarproject/bramble/api/transport/KeyManager.java

@@ -113,9 +113,25 @@ public interface KeyManager {
 	/**
 	 * Looks up the given tag and returns a {@link StreamContext} for reading
 	 * from the corresponding stream, or null if an error occurs or the tag was
-	 * unexpected.
+	 * unexpected. Marks the tag as recognised and updates the reordering
+	 * window.
 	 */
 	@Nullable
 	StreamContext getStreamContext(TransportId t, byte[] tag)
 			throws DbException;
+
+	/**
+	 * Looks up the given tag and returns a {@link StreamContext} for reading
+	 * from the corresponding stream, or null if an error occurs or the tag was
+	 * unexpected. Only returns the StreamContext; does not mark the tag as
+	 * recognised.
+	 */
+	@Nullable
+	StreamContext getStreamContextOnly(TransportId t, byte[] tag)
+			throws DbException;
+
+	/**
+	 * Marks the tag as recognised and updates the reordering window.
+	 */
+	void markTagAsRecognised(TransportId t, byte[] tag) throws DbException;
 }

bramble-api/src/main/java/org/briarproject/bramble/util/NetworkUtils.java

@@ -26,7 +26,7 @@ public class NetworkUtils {
 			// Despite what the docs say, the return value can be null
 			//noinspection ConstantConditions
 			return ifaces == null ? emptyList() : list(ifaces);
-		} catch (SocketException e) {
+		} catch (SocketException | NullPointerException e) {
 			logException(LOG, WARNING, e);
 			return emptyList();
 		}

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

@@ -1,12 +1,17 @@
 package org.briarproject.bramble.test;
 
 import org.jmock.Mockery;
+import org.jmock.lib.concurrent.Synchroniser;
 import org.junit.After;
 
 public abstract class BrambleMockTestCase extends BrambleTestCase {
 
 	protected final Mockery context = new Mockery();
 
+	public BrambleMockTestCase() {
+		context.setThreadingPolicy(new Synchroniser());
+	}
+
 	@After
 	public void checkExpectations() {
 		context.assertIsSatisfied();

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

@@ -1,17 +1,46 @@
 package org.briarproject.bramble.test;
 
-import java.lang.Thread.UncaughtExceptionHandler;
+import org.junit.After;
+import org.junit.Before;
 
-import static org.junit.Assert.fail;
+import java.lang.Thread.UncaughtExceptionHandler;
+import java.util.logging.Logger;
+
+import javax.annotation.Nullable;
+
+import static java.util.logging.Level.WARNING;
+import static java.util.logging.Logger.getLogger;
 
 public abstract class BrambleTestCase {
 
+	private static final Logger LOG =
+			getLogger(BrambleTestCase.class.getName());
+
+	@Nullable
+	protected volatile Throwable exceptionInBackgroundThread = null;
+
 	public BrambleTestCase() {
 		// Ensure exceptions thrown on worker threads cause tests to fail
 		UncaughtExceptionHandler fail = (thread, throwable) -> {
-			throwable.printStackTrace();
+			LOG.log(WARNING, "Caught unhandled exception", throwable);
-			fail();
+			exceptionInBackgroundThread = throwable;
 		};
 		Thread.setDefaultUncaughtExceptionHandler(fail);
 	}
+
+	@Before
+	public void beforeBrambleTestCase() {
+		exceptionInBackgroundThread = null;
+	}
+
+	@After
+	public void afterBrambleTestCase() {
+		Throwable thrown = exceptionInBackgroundThread;
+		if (thrown != null) {
+			LOG.log(WARNING,
+					"Background thread has thrown an exception unexpectedly",
+					thrown);
+			throw new AssertionError(thrown);
+		}
+	}
 }

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

@@ -12,10 +12,20 @@ import org.briarproject.bramble.api.crypto.PublicKey;
 import org.briarproject.bramble.api.crypto.SecretKey;
 import org.briarproject.bramble.api.crypto.SignaturePrivateKey;
 import org.briarproject.bramble.api.crypto.SignaturePublicKey;
+import org.briarproject.bramble.api.db.CommitAction;
+import org.briarproject.bramble.api.db.EventAction;
+import org.briarproject.bramble.api.db.Transaction;
+import org.briarproject.bramble.api.event.Event;
 import org.briarproject.bramble.api.identity.Author;
 import org.briarproject.bramble.api.identity.AuthorId;
 import org.briarproject.bramble.api.identity.Identity;
 import org.briarproject.bramble.api.identity.LocalAuthor;
+import org.briarproject.bramble.api.mailbox.MailboxAuthToken;
+import org.briarproject.bramble.api.mailbox.MailboxFolderId;
+import org.briarproject.bramble.api.mailbox.MailboxProperties;
+import org.briarproject.bramble.api.mailbox.MailboxUpdate;
+import org.briarproject.bramble.api.mailbox.MailboxUpdateWithMailbox;
+import org.briarproject.bramble.api.mailbox.MailboxVersion;
 import org.briarproject.bramble.api.plugin.TransportId;
 import org.briarproject.bramble.api.properties.TransportProperties;
 import org.briarproject.bramble.api.sync.ClientId;
@@ -25,7 +35,11 @@ import org.briarproject.bramble.api.sync.Message;
 import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.bramble.util.IoUtils;
 
+import java.io.ByteArrayOutputStream;
 import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileOutputStream;
+import java.io.IOException;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
@@ -35,6 +49,8 @@ import java.util.Map;
 import java.util.Random;
 import java.util.concurrent.atomic.AtomicInteger;
 
+import javax.annotation.Nullable;
+
 import static java.util.Arrays.asList;
 import static org.briarproject.bramble.api.crypto.CryptoConstants.MAX_AGREEMENT_PUBLIC_KEY_BYTES;
 import static org.briarproject.bramble.api.crypto.CryptoConstants.MAX_SIGNATURE_PUBLIC_KEY_BYTES;
@@ -45,6 +61,7 @@ import static org.briarproject.bramble.api.properties.TransportPropertyConstants
 import static org.briarproject.bramble.api.sync.ClientId.MAX_CLIENT_ID_LENGTH;
 import static org.briarproject.bramble.api.sync.SyncConstants.MAX_GROUP_DESCRIPTOR_LENGTH;
 import static org.briarproject.bramble.api.sync.SyncConstants.MAX_MESSAGE_BODY_LENGTH;
+import static org.briarproject.bramble.util.IoUtils.copyAndClose;
 import static org.briarproject.bramble.util.StringUtils.getRandomString;
 
 public class TestUtils {
@@ -209,6 +226,37 @@ public class TestUtils {
 				getAgreementPublicKey(), verified);
 	}
 
+	public static MailboxProperties getMailboxProperties(boolean owner,
+			List<MailboxVersion> serverSupports) {
+		String baseUrl = "http://" + getRandomString(56) + ".onion"; // TODO
+		MailboxAuthToken authToken = new MailboxAuthToken(getRandomId());
+		if (owner) {
+			return new MailboxProperties(baseUrl, authToken, serverSupports);
+		}
+		MailboxFolderId inboxId = new MailboxFolderId(getRandomId());
+		MailboxFolderId outboxId = new MailboxFolderId(getRandomId());
+		return new MailboxProperties(baseUrl, authToken, serverSupports,
+				inboxId, outboxId);
+	}
+
+	public static void writeBytes(File file, byte[] bytes)
+			throws IOException {
+		FileOutputStream outputStream = new FileOutputStream(file);
+		//noinspection TryFinallyCanBeTryWithResources
+		try {
+			outputStream.write(bytes);
+		} finally {
+			outputStream.close();
+		}
+	}
+
+	public static byte[] readBytes(File file) throws IOException {
+		ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
+		FileInputStream inputStream = new FileInputStream(file);
+		copyAndClose(inputStream, outputStream);
+		return outputStream.toByteArray();
+	}
+
 	public static double getMedian(Collection<? extends Number> samples) {
 		int size = samples.size();
 		if (size == 0) throw new IllegalArgumentException();
@@ -243,9 +291,48 @@ public class TestUtils {
 		return Math.sqrt(getVariance(samples));
 	}
 
-	public static boolean isOptionalTestEnabled(Class testClass) {
+	public static boolean isOptionalTestEnabled(Class<?> testClass) {
 		String optionalTests = System.getenv("OPTIONAL_TESTS");
 		return optionalTests != null &&
 				asList(optionalTests.split(",")).contains(testClass.getName());
 	}
+
+	public static boolean mailboxUpdateEqual(@Nullable MailboxUpdate a,
+			@Nullable MailboxUpdate b) {
+		if (a == null || b == null) {
+			return a == b;
+		}
+		if (!a.hasMailbox() && !b.hasMailbox()) {
+			return a.getClientSupports().equals(b.getClientSupports());
+		} else if (a.hasMailbox() && b.hasMailbox()) {
+			MailboxUpdateWithMailbox am = (MailboxUpdateWithMailbox) a;
+			MailboxUpdateWithMailbox bm = (MailboxUpdateWithMailbox) b;
+			return am.getClientSupports().equals(bm.getClientSupports()) &&
+					mailboxPropertiesEqual(am.getMailboxProperties(),
+							bm.getMailboxProperties());
+		}
+		return false;
+	}
+
+	public static boolean mailboxPropertiesEqual(@Nullable MailboxProperties a,
+			@Nullable MailboxProperties b) {
+		if (a == null || b == null) {
+			return a == b;
+		}
+		return a.getOnion().equals(b.getOnion()) &&
+				a.getAuthToken().equals(b.getAuthToken()) &&
+				a.isOwner() == b.isOwner() &&
+				a.getServerSupports().equals(b.getServerSupports());
+	}
+
+	public static boolean hasEvent(Transaction txn,
+			Class<? extends Event> eventClass) {
+		for (CommitAction action : txn.getActions()) {
+			if (action instanceof EventAction) {
+				Event event = ((EventAction) action).getEvent();
+				if (eventClass.isInstance(event)) return true;
+			}
+		}
+		return false;
+	}
 }

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

@@ -0,0 +1,36 @@
+package org.briarproject.bramble.test;
+
+import org.junit.Test;
+
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.fail;
+
+public class ThreadExceptionTest extends BrambleTestCase {
+
+	@Test(expected = AssertionError.class)
+	public void testAssertionErrorMakesTestCaseFail() {
+		// This is what BrambleTestCase does, too:
+		fail();
+	}
+
+	@Test
+	public void testExceptionInThreadMakesTestCaseFail() {
+		Thread t = new Thread(() -> {
+			System.out.println("thread before exception");
+			throw new RuntimeException("boom");
+		});
+
+		t.start();
+		try {
+			t.join();
+			System.out.println("joined thread");
+		} catch (InterruptedException e) {
+			System.out.println("interrupted while joining thread");
+			fail();
+		}
+
+		assertNotNull(exceptionInBackgroundThread);
+		exceptionInBackgroundThread = null;
+	}
+
+}

bramble-api/witness.gradle

@@ -1,6 +1,7 @@
 dependencyVerification {
     verify = [
         'cglib:cglib:3.2.8:cglib-3.2.8.jar:3f64de999ecc5595dc84ca8ff0879d8a34c8623f9ef3c517a53ed59023fcb9db',
+        'com.fasterxml.jackson.core:jackson-annotations:2.13.0:jackson-annotations-2.13.0.jar:81f9724d8843e8b08f8f6c0609e7a2b030d00c34861c4ac7e2099a7235047d6f',
         'com.google.code.findbugs:annotations:3.0.1:annotations-3.0.1.jar:6b47ff0a6de0ce17cbedc3abb0828ca5bce3009d53ea47b3723ff023c4742f79',
         'com.google.code.findbugs:jsr305:3.0.2:jsr305-3.0.2.jar:766ad2a0783f2687962c8ad74ceecc38a28b9f72a2d085ee438b7813e928d0c7',
         'com.google.dagger:dagger:2.33:dagger-2.33.jar:d8798c5b8cf6b125234e33af5c6293bb9f2208ce29b57924c35b8c0be7b6bdcb',

bramble-core/build.gradle

@@ -10,12 +10,17 @@ apply from: '../dagger.gradle'
 
 dependencies {
 	implementation project(path: ':bramble-api', configuration: 'default')
-	implementation 'org.bouncycastle:bcprov-jdk15on:1.69'
+	implementation 'org.bouncycastle:bcprov-jdk15to18:1.70'
+	//noinspection GradleDependency
 	implementation 'com.h2database:h2:1.4.192' // The last version that supports Java 1.6
 	implementation 'org.bitlet:weupnp:0.1.4'
 	implementation 'net.i2p.crypto:eddsa:0.2.0'
 	implementation 'org.whispersystems:curve25519-java:0.5.0'
-	implementation 'org.briarproject:jtorctl:0.3'
+	implementation 'org.briarproject:jtorctl:0.4'
+
+	//noinspection GradleDependency
+	implementation "com.squareup.okhttp3:okhttp:$okhttp_version"
+	implementation "com.fasterxml.jackson.core:jackson-databind:$jackson_version"
 
 	annotationProcessor "com.google.dagger:dagger-compiler:$dagger_version"
 
@@ -25,7 +30,8 @@ dependencies {
 	testImplementation "junit:junit:$junit_version"
 	testImplementation "org.jmock:jmock:$jmock_version"
 	testImplementation "org.jmock:jmock-junit4:$jmock_version"
-	testImplementation "org.jmock:jmock-legacy:$jmock_version"
+	testImplementation "org.jmock:jmock-imposters:$jmock_version"
+	testImplementation "com.squareup.okhttp3:mockwebserver:4.9.3"
 
 	testAnnotationProcessor "com.google.dagger:dagger-compiler:$dagger_version"
 

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

@@ -6,6 +6,7 @@ import org.briarproject.bramble.crypto.CryptoExecutorModule;
 import org.briarproject.bramble.db.DatabaseExecutorModule;
 import org.briarproject.bramble.identity.IdentityModule;
 import org.briarproject.bramble.lifecycle.LifecycleModule;
+import org.briarproject.bramble.mailbox.MailboxModule;
 import org.briarproject.bramble.plugin.PluginModule;
 import org.briarproject.bramble.properties.PropertiesModule;
 import org.briarproject.bramble.rendezvous.RendezvousModule;
@@ -28,6 +29,8 @@ public interface BrambleCoreEagerSingletons {
 
 	void inject(LifecycleModule.EagerSingletons init);
 
+	void inject(MailboxModule.EagerSingletons init);
+
 	void inject(PluginModule.EagerSingletons init);
 
 	void inject(PropertiesModule.EagerSingletons init);
@@ -51,6 +54,7 @@ public interface BrambleCoreEagerSingletons {
 			c.inject(new DatabaseExecutorModule.EagerSingletons());
 			c.inject(new IdentityModule.EagerSingletons());
 			c.inject(new LifecycleModule.EagerSingletons());
+			c.inject(new MailboxModule.EagerSingletons());
 			c.inject(new RendezvousModule.EagerSingletons());
 			c.inject(new PluginModule.EagerSingletons());
 			c.inject(new PropertiesModule.EagerSingletons());

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

@@ -14,6 +14,7 @@ import org.briarproject.bramble.identity.IdentityModule;
 import org.briarproject.bramble.io.IoModule;
 import org.briarproject.bramble.keyagreement.KeyAgreementModule;
 import org.briarproject.bramble.lifecycle.LifecycleModule;
+import org.briarproject.bramble.mailbox.MailboxModule;
 import org.briarproject.bramble.plugin.PluginModule;
 import org.briarproject.bramble.properties.PropertiesModule;
 import org.briarproject.bramble.record.RecordModule;
@@ -43,6 +44,7 @@ import dagger.Module;
 		IoModule.class,
 		KeyAgreementModule.class,
 		LifecycleModule.class,
+		MailboxModule.class,
 		PluginModule.class,
 		PropertiesModule.class,
 		RecordModule.class,

bramble-core/src/main/java/org/briarproject/bramble/client/ClientHelperImpl.java

@@ -1,6 +1,7 @@
 package org.briarproject.bramble.client;
 
 import org.briarproject.bramble.api.FormatException;
+import org.briarproject.bramble.api.UniqueId;
 import org.briarproject.bramble.api.client.ClientHelper;
 import org.briarproject.bramble.api.contact.ContactId;
 import org.briarproject.bramble.api.crypto.CryptoComponent;
@@ -22,6 +23,12 @@ import org.briarproject.bramble.api.db.Metadata;
 import org.briarproject.bramble.api.db.Transaction;
 import org.briarproject.bramble.api.identity.Author;
 import org.briarproject.bramble.api.identity.AuthorFactory;
+import org.briarproject.bramble.api.mailbox.MailboxAuthToken;
+import org.briarproject.bramble.api.mailbox.MailboxFolderId;
+import org.briarproject.bramble.api.mailbox.MailboxProperties;
+import org.briarproject.bramble.api.mailbox.MailboxUpdate;
+import org.briarproject.bramble.api.mailbox.MailboxUpdateWithMailbox;
+import org.briarproject.bramble.api.mailbox.MailboxVersion;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.TransportId;
 import org.briarproject.bramble.api.properties.TransportProperties;
@@ -29,13 +36,16 @@ import org.briarproject.bramble.api.sync.GroupId;
 import org.briarproject.bramble.api.sync.Message;
 import org.briarproject.bramble.api.sync.MessageFactory;
 import org.briarproject.bramble.api.sync.MessageId;
+import org.briarproject.bramble.util.Base32;
 
 import java.io.ByteArrayInputStream;
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
 import java.security.GeneralSecurityException;
+import java.util.ArrayList;
 import java.util.Collection;
 import java.util.HashMap;
+import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
 
@@ -46,6 +56,12 @@ import static org.briarproject.bramble.api.client.ContactGroupConstants.GROUP_KE
 import static org.briarproject.bramble.api.identity.Author.FORMAT_VERSION;
 import static org.briarproject.bramble.api.identity.AuthorConstants.MAX_AUTHOR_NAME_LENGTH;
 import static org.briarproject.bramble.api.identity.AuthorConstants.MAX_PUBLIC_KEY_LENGTH;
+import static org.briarproject.bramble.api.mailbox.MailboxUpdateManager.PROP_COUNT;
+import static org.briarproject.bramble.api.mailbox.MailboxUpdateManager.PROP_KEY_AUTHTOKEN;
+import static org.briarproject.bramble.api.mailbox.MailboxUpdateManager.PROP_KEY_INBOXID;
+import static org.briarproject.bramble.api.mailbox.MailboxUpdateManager.PROP_KEY_ONION;
+import static org.briarproject.bramble.api.mailbox.MailboxUpdateManager.PROP_KEY_OUTBOXID;
+import static org.briarproject.bramble.api.mailbox.MailboxUpdateManager.PROP_ONION_LENGTH;
 import static org.briarproject.bramble.api.properties.TransportPropertyConstants.MAX_PROPERTIES_PER_TRANSPORT;
 import static org.briarproject.bramble.api.properties.TransportPropertyConstants.MAX_PROPERTY_LENGTH;
 import static org.briarproject.bramble.util.ValidationUtils.checkLength;
@@ -399,6 +415,69 @@ class ClientHelperImpl implements ClientHelper {
 		return tpMap;
 	}
 
+	@Override
+	public MailboxUpdate parseAndValidateMailboxUpdate(BdfList clientSupports,
+			BdfList serverSupports, BdfDictionary properties)
+			throws FormatException {
+		List<MailboxVersion> clientSupportsList =
+				parseMailboxVersionList(clientSupports);
+		List<MailboxVersion> serverSupportsList =
+				parseMailboxVersionList(serverSupports);
+
+		// We must always learn what Mailbox API version(s) the client supports
+		if (clientSupports.isEmpty()) {
+			throw new FormatException();
+		}
+		if (properties.isEmpty()) {
+			// No mailbox -- cannot claim to support any API versions!
+			if (!serverSupports.isEmpty()) {
+				throw new FormatException();
+			}
+			return new MailboxUpdate(clientSupportsList);
+		}
+		// Mailbox must be accompanied by the Mailbox API version(s) it supports
+		if (serverSupports.isEmpty()) {
+			throw new FormatException();
+		}
+		// Accepting more props than we need, for forward compatibility
+		if (properties.size() < PROP_COUNT) {
+			throw new FormatException();
+		}
+		String onion = properties.getString(PROP_KEY_ONION);
+		checkLength(onion, PROP_ONION_LENGTH);
+		try {
+			Base32.decode(onion, true);
+		} catch (IllegalArgumentException e) {
+			throw new FormatException();
+		}
+		byte[] authToken = properties.getRaw(PROP_KEY_AUTHTOKEN);
+		checkLength(authToken, UniqueId.LENGTH);
+		byte[] inboxId = properties.getRaw(PROP_KEY_INBOXID);
+		checkLength(inboxId, UniqueId.LENGTH);
+		byte[] outboxId = properties.getRaw(PROP_KEY_OUTBOXID);
+		checkLength(outboxId, UniqueId.LENGTH);
+		String baseUrl = "http://" + onion + ".onion"; // TODO
+		MailboxProperties props = new MailboxProperties(baseUrl,
+				new MailboxAuthToken(authToken), serverSupportsList,
+				new MailboxFolderId(inboxId), new MailboxFolderId(outboxId));
+		return new MailboxUpdateWithMailbox(clientSupportsList, props);
+	}
+
+	@Override
+	public List<MailboxVersion> parseMailboxVersionList(BdfList bdfList)
+			throws FormatException {
+		List<MailboxVersion> list = new ArrayList<>();
+		for (int i = 0; i < bdfList.size(); i++) {
+			BdfList element = bdfList.getList(i);
+			if (element.size() != 2) {
+				throw new FormatException();
+			}
+			list.add(new MailboxVersion(element.getLong(0).intValue(),
+					element.getLong(1).intValue()));
+		}
+		return list;
+	}
+
 	@Override
 	public ContactId getContactId(Transaction txn, GroupId contactGroupId)
 			throws DbException {

bramble-core/src/main/java/org/briarproject/bramble/contact/ContactManagerImpl.java

@@ -121,28 +121,40 @@ class ContactManagerImpl implements ContactManager, EventListener {
 
 	@Override
 	public String getHandshakeLink() throws DbException {
-		KeyPair keyPair = db.transactionWithResult(true,
+		return db.transactionWithResult(true, this::getHandshakeLink);
-				identityManager::getHandshakeKeys);
+	}
+
+	@Override
+	public String getHandshakeLink(Transaction txn) throws DbException {
+		KeyPair keyPair = identityManager.getHandshakeKeys(txn);
 		return pendingContactFactory.createHandshakeLink(keyPair.getPublic());
 	}
 
+	@Override
+	public PendingContact addPendingContact(Transaction txn, String link,
+			String alias)
+			throws DbException, FormatException, GeneralSecurityException {
+		PendingContact p =
+				pendingContactFactory.createPendingContact(link, alias);
+		AuthorId local = identityManager.getLocalAuthor(txn).getId();
+		db.addPendingContact(txn, p, local);
+		KeyPair ourKeyPair = identityManager.getHandshakeKeys(txn);
+		keyManager.addPendingContact(txn, p.getId(), p.getPublicKey(),
+				ourKeyPair);
+		return p;
+	}
+
 	@Override
 	public PendingContact addPendingContact(String link, String alias)
 			throws DbException, FormatException, GeneralSecurityException {
-		PendingContact p =
-				pendingContactFactory.createPendingContact(link, alias);
 		Transaction txn = db.startTransaction(false);
 		try {
-			AuthorId local = identityManager.getLocalAuthor(txn).getId();
+			PendingContact p = addPendingContact(txn, link, alias);
-			db.addPendingContact(txn, p, local);
-			KeyPair ourKeyPair = identityManager.getHandshakeKeys(txn);
-			keyManager.addPendingContact(txn, p.getId(), p.getPublicKey(),
-					ourKeyPair);
 			db.commitTransaction(txn);
+			return p;
 		} finally {
 			db.endTransaction(txn);
 		}
-		return p;
 	}
 
 	@Override
@@ -154,8 +166,14 @@ class ContactManagerImpl implements ContactManager, EventListener {
 	@Override
 	public Collection<Pair<PendingContact, PendingContactState>> getPendingContacts()
 			throws DbException {
-		Collection<PendingContact> pendingContacts =
+		return db.transactionWithResult(true, this::getPendingContacts);
-				db.transactionWithResult(true, db::getPendingContacts);
+	}
+
+	@Override
+	public Collection<Pair<PendingContact, PendingContactState>> getPendingContacts(
+			Transaction txn)
+			throws DbException {
+		Collection<PendingContact> pendingContacts = db.getPendingContacts(txn);
 		List<Pair<PendingContact, PendingContactState>> pairs =
 				new ArrayList<>(pendingContacts.size());
 		for (PendingContact p : pendingContacts) {
@@ -168,7 +186,13 @@ class ContactManagerImpl implements ContactManager, EventListener {
 
 	@Override
 	public void removePendingContact(PendingContactId p) throws DbException {
-		db.transaction(false, txn -> db.removePendingContact(txn, p));
+		db.transaction(false, txn -> removePendingContact(txn, p));
+	}
+
+	@Override
+	public void removePendingContact(Transaction txn, PendingContactId p)
+			throws DbException {
+		db.removePendingContact(txn, p);
 		states.remove(p);
 	}
 

bramble-core/src/main/java/org/briarproject/bramble/crypto/CryptoComponentImpl.java

@@ -7,6 +7,8 @@ import net.i2p.crypto.eddsa.KeyPairGenerator;
 import org.bouncycastle.crypto.CryptoException;
 import org.bouncycastle.crypto.Digest;
 import org.bouncycastle.crypto.digests.Blake2bDigest;
+import org.bouncycastle.crypto.digests.SHA3Digest;
+import org.briarproject.bramble.api.UniqueId;
 import org.briarproject.bramble.api.crypto.AgreementPrivateKey;
 import org.briarproject.bramble.api.crypto.AgreementPublicKey;
 import org.briarproject.bramble.api.crypto.CryptoComponent;
@@ -21,11 +23,13 @@ import org.briarproject.bramble.api.crypto.SignaturePrivateKey;
 import org.briarproject.bramble.api.crypto.SignaturePublicKey;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.system.SecureRandomProvider;
+import org.briarproject.bramble.util.Base32;
 import org.briarproject.bramble.util.ByteUtils;
 import org.briarproject.bramble.util.StringUtils;
 import org.whispersystems.curve25519.Curve25519;
 import org.whispersystems.curve25519.Curve25519KeyPair;
 
+import java.nio.charset.Charset;
 import java.security.GeneralSecurityException;
 import java.security.NoSuchAlgorithmException;
 import java.security.Provider;
@@ -38,6 +42,7 @@ import javax.inject.Inject;
 
 import static java.lang.System.arraycopy;
 import static java.util.logging.Level.INFO;
+import static java.util.logging.Logger.getLogger;
 import static org.briarproject.bramble.api.crypto.CryptoConstants.KEY_TYPE_AGREEMENT;
 import static org.briarproject.bramble.api.crypto.CryptoConstants.KEY_TYPE_SIGNATURE;
 import static org.briarproject.bramble.api.crypto.DecryptionResult.INVALID_CIPHERTEXT;
@@ -51,13 +56,15 @@ import static org.briarproject.bramble.util.LogUtils.now;
 class CryptoComponentImpl implements CryptoComponent {
 
 	private static final Logger LOG =
-			Logger.getLogger(CryptoComponentImpl.class.getName());
+			getLogger(CryptoComponentImpl.class.getName());
 
 	private static final int SIGNATURE_KEY_PAIR_BITS = 256;
 	private static final int STORAGE_IV_BYTES = 24; // 196 bits
 	private static final int PBKDF_SALT_BYTES = 32; // 256 bits
 	private static final byte PBKDF_FORMAT_SCRYPT = 0;
 	private static final byte PBKDF_FORMAT_SCRYPT_STRENGTHENED = 1;
+	private static final byte ONION_HS_PROTOCOL_VERSION = 3;
+	private static final int ONION_CHECKSUM_BYTES = 2;
 
 	private final SecureRandom secureRandom;
 	private final PasswordBasedKdf passwordBasedKdf;
@@ -123,6 +130,13 @@ class CryptoComponentImpl implements CryptoComponent {
 		}
 	}
 
+	@Override
+	public UniqueId generateUniqueId() {
+		byte[] b = new byte[UniqueId.LENGTH];
+		secureRandom.nextBytes(b);
+		return new UniqueId(b);
+	}
+
 	@Override
 	public SecretKey generateSecretKey() {
 		byte[] b = new byte[SecretKey.LENGTH];
@@ -442,4 +456,21 @@ class CryptoComponentImpl implements CryptoComponent {
 	public String asciiArmour(byte[] b, int lineLength) {
 		return AsciiArmour.wrap(b, lineLength);
 	}
+
+	@Override
+	public String encodeOnion(byte[] publicKey) {
+		Digest digest = new SHA3Digest(256);
+		byte[] label = ".onion checksum".getBytes(Charset.forName("US-ASCII"));
+		digest.update(label, 0, label.length);
+		digest.update(publicKey, 0, publicKey.length);
+		digest.update(ONION_HS_PROTOCOL_VERSION);
+		byte[] checksum = new byte[digest.getDigestSize()];
+		digest.doFinal(checksum, 0);
+		byte[] address = new byte[publicKey.length + ONION_CHECKSUM_BYTES + 1];
+		arraycopy(publicKey, 0, address, 0, publicKey.length);
+		arraycopy(checksum, 0, address, publicKey.length, ONION_CHECKSUM_BYTES);
+		address[address.length - 1] = ONION_HS_PROTOCOL_VERSION;
+		return Base32.encode(address).toLowerCase();
+	}
+
 }

bramble-core/src/main/java/org/briarproject/bramble/db/Database.java

@@ -406,6 +406,12 @@ interface Database<T> {
 	Collection<MessageId> getMessageIds(T txn, GroupId g, Metadata query)
 			throws DbException;
 
+	/**
+	 * Returns the length of the given message in bytes, including the
+	 * message header.
+	 */
+	int getMessageLength(T txn, MessageId m) throws DbException;
+
 	/**
 	 * Returns the metadata for all delivered messages in the given group.
 	 * <p/>
@@ -496,7 +502,8 @@ interface Database<T> {
 
 	/**
 	 * Returns the IDs of some messages that are eligible to be sent to the
-	 * given contact, up to the given total length.
+	 * given contact. The total length of the messages including record headers
+	 * will be no more than the given capacity.
 	 * <p/>
 	 * Unlike {@link #getUnackedMessagesToSend(Object, ContactId)} this method
 	 * does not return messages that have already been sent unless they are
@@ -504,20 +511,20 @@ interface Database<T> {
 	 * <p/>
 	 * Read-only.
 	 */
-	Collection<MessageId> getMessagesToSend(T txn, ContactId c, int maxLength,
+	Collection<MessageId> getMessagesToSend(T txn, ContactId c, long capacity,
 			long maxLatency) throws DbException;
 
 	/**
 	 * Returns the IDs of all messages that are eligible to be sent to the
-	 * given contact, together with their raw lengths.
+	 * given contact.
 	 * <p/>
-	 * Unlike {@link #getMessagesToSend(Object, ContactId, int, long)} this
+	 * Unlike {@link #getMessagesToSend(Object, ContactId, long, long)} this
 	 * method may return messages that have already been sent and are not yet
 	 * due for retransmission.
 	 * <p/>
 	 * Read-only.
 	 */
-	Map<MessageId, Integer> getUnackedMessagesToSend(T txn, ContactId c)
+	Collection<MessageId> getUnackedMessagesToSend(T txn, ContactId c)
 			throws DbException;
 
 	/**
@@ -598,13 +605,14 @@ interface Database<T> {
 
 	/**
 	 * Returns the IDs of some messages that are eligible to be sent to the
-	 * given contact and have been requested by the contact, up to the given
+	 * given contact and have been requested by the contact. The total length
-	 * total length.
+	 * of the messages including record headers will be no more than the given
+	 * capacity.
 	 * <p/>
 	 * Read-only.
 	 */
 	Collection<MessageId> getRequestedMessagesToSend(T txn, ContactId c,
-			int maxLength, long maxLatency) throws DbException;
+			long capacity, long maxLatency) throws DbException;
 
 	/**
 	 * Returns all settings in the given namespace.
@@ -757,6 +765,14 @@ interface Database<T> {
 	 */
 	void resetExpiryTime(T txn, ContactId c, MessageId m) throws DbException;
 
+	/**
+	 * Resets the transmission count, expiry time and max latency of all
+	 * messages that are eligible to be sent to the given contact. This includes
+	 * messages that have already been sent and are not yet due for
+	 * retransmission.
+	 */
+	void resetUnackedMessagesToSend(T txn, ContactId c) throws DbException;
+
 	/**
 	 * Sets the cleanup timer duration for the given message. This does not
 	 * start the message's cleanup timer.
@@ -841,12 +857,14 @@ interface Database<T> {
 	void stopCleanupTimer(T txn, MessageId m) throws DbException;
 
 	/**
-	 * Updates the transmission count, expiry time and estimated time of arrival
+	 * Updates the transmission count, expiry time and max latency of the given
-	 * of the given message with respect to the given contact, using the latency
+	 * message with respect to the given contact.
-	 * of the transport over which it was sent.
+	 *
+	 * @param maxLatency latency of the transport over which the message was
+	 * sent.
 	 */
-	void updateExpiryTimeAndEta(T txn, ContactId c, MessageId m, long maxLatency)
+	void updateRetransmissionData(T txn, ContactId c, MessageId m,
-			throws DbException;
+			long maxLatency) throws DbException;
 
 	/**
 	 * Stores the given transport keys, deleting any keys they have replaced.

bramble-core/src/main/java/org/briarproject/bramble/db/DatabaseComponentImpl.java

@@ -75,7 +75,6 @@ import org.briarproject.bramble.api.transport.TransportKeys;
 
 import java.util.ArrayList;
 import java.util.Collection;
-import java.util.Collections;
 import java.util.List;
 import java.util.Map;
 import java.util.concurrent.Executor;
@@ -87,6 +86,7 @@ import javax.annotation.Nullable;
 import javax.annotation.concurrent.ThreadSafe;
 import javax.inject.Inject;
 
+import static java.util.Collections.singletonList;
 import static java.util.logging.Level.WARNING;
 import static java.util.logging.Logger.getLogger;
 import static org.briarproject.bramble.api.sync.Group.Visibility.INVISIBLE;
@@ -424,53 +424,27 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 	@Nullable
 	@Override
 	public Collection<Message> generateBatch(Transaction transaction,
-			ContactId c, int maxLength, long maxLatency) throws DbException {
+			ContactId c, long capacity, long maxLatency) throws DbException {
 		if (transaction.isReadOnly()) throw new IllegalArgumentException();
 		T txn = unbox(transaction);
 		if (!db.containsContact(txn, c))
 			throw new NoSuchContactException();
 		Collection<MessageId> ids =
-				db.getMessagesToSend(txn, c, maxLength, maxLatency);
+				db.getMessagesToSend(txn, c, capacity, maxLatency);
+		if (ids.isEmpty()) return null;
 		long totalLength = 0;
 		List<Message> messages = new ArrayList<>(ids.size());
 		for (MessageId m : ids) {
 			Message message = db.getMessage(txn, m);
 			totalLength += message.getRawLength();
 			messages.add(message);
-			db.updateExpiryTimeAndEta(txn, c, m, maxLatency);
+			db.updateRetransmissionData(txn, c, m, maxLatency);
 		}
-		if (ids.isEmpty()) return null;
 		db.lowerRequestedFlag(txn, c, ids);
 		transaction.attach(new MessagesSentEvent(c, ids, totalLength));
 		return messages;
 	}
 
-	@Override
-	public Collection<Message> generateBatch(Transaction transaction,
-			ContactId c, Collection<MessageId> ids, long maxLatency)
-			throws DbException {
-		if (transaction.isReadOnly()) throw new IllegalArgumentException();
-		T txn = unbox(transaction);
-		if (!db.containsContact(txn, c))
-			throw new NoSuchContactException();
-		long totalLength = 0;
-		List<Message> messages = new ArrayList<>(ids.size());
-		List<MessageId> sentIds = new ArrayList<>(ids.size());
-		for (MessageId m : ids) {
-			if (db.containsVisibleMessage(txn, c, m)) {
-				Message message = db.getMessage(txn, m);
-				totalLength += message.getRawLength();
-				messages.add(message);
-				sentIds.add(m);
-				db.updateExpiryTimeAndEta(txn, c, m, maxLatency);
-			}
-		}
-		if (messages.isEmpty()) return messages;
-		db.lowerRequestedFlag(txn, c, sentIds);
-		transaction.attach(new MessagesSentEvent(c, sentIds, totalLength));
-		return messages;
-	}
-
 	@Nullable
 	@Override
 	public Offer generateOffer(Transaction transaction, ContactId c,
@@ -483,7 +457,7 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 				db.getMessagesToOffer(txn, c, maxMessages, maxLatency);
 		if (ids.isEmpty()) return null;
 		for (MessageId m : ids)
-			db.updateExpiryTimeAndEta(txn, c, m, maxLatency);
+			db.updateRetransmissionData(txn, c, m, maxLatency);
 		return new Offer(ids);
 	}
 
@@ -505,22 +479,22 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 	@Nullable
 	@Override
 	public Collection<Message> generateRequestedBatch(Transaction transaction,
-			ContactId c, int maxLength, long maxLatency) throws DbException {
+			ContactId c, long capacity, long maxLatency) throws DbException {
 		if (transaction.isReadOnly()) throw new IllegalArgumentException();
 		T txn = unbox(transaction);
 		if (!db.containsContact(txn, c))
 			throw new NoSuchContactException();
 		Collection<MessageId> ids =
-				db.getRequestedMessagesToSend(txn, c, maxLength, maxLatency);
+				db.getRequestedMessagesToSend(txn, c, capacity, maxLatency);
+		if (ids.isEmpty()) return null;
 		long totalLength = 0;
 		List<Message> messages = new ArrayList<>(ids.size());
 		for (MessageId m : ids) {
 			Message message = db.getMessage(txn, m);
 			totalLength += message.getRawLength();
 			messages.add(message);
-			db.updateExpiryTimeAndEta(txn, c, m, maxLatency);
+			db.updateRetransmissionData(txn, c, m, maxLatency);
 		}
-		if (ids.isEmpty()) return null;
 		db.lowerRequestedFlag(txn, c, ids);
 		transaction.attach(new MessagesSentEvent(c, ids, totalLength));
 		return messages;
@@ -635,6 +609,24 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 		return db.getMessageIds(txn, g, query);
 	}
 
+	@Override
+	public Collection<MessageId> getMessagesToAck(Transaction transaction,
+			ContactId c, int maxMessages) throws DbException {
+		T txn = unbox(transaction);
+		if (!db.containsContact(txn, c))
+			throw new NoSuchContactException();
+		return db.getMessagesToAck(txn, c, maxMessages);
+	}
+
+	@Override
+	public Collection<MessageId> getMessagesToSend(Transaction transaction,
+			ContactId c, long capacity, long maxLatency) throws DbException {
+		T txn = unbox(transaction);
+		if (!db.containsContact(txn, c))
+			throw new NoSuchContactException();
+		return db.getMessagesToSend(txn, c, capacity, maxLatency);
+	}
+
 	@Override
 	public Collection<MessageId> getMessagesToValidate(Transaction transaction)
 			throws DbException {
@@ -740,16 +732,44 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 		return status;
 	}
 
+	@Nullable
 	@Override
-	public Map<MessageId, Integer> getUnackedMessagesToSend(
+	public Message getMessageToSend(Transaction transaction, ContactId c,
-			Transaction transaction,
+			MessageId m, long maxLatency, boolean markAsSent)
-			ContactId c) throws DbException {
+			throws DbException {
+		if (transaction.isReadOnly()) throw new IllegalArgumentException();
+		T txn = unbox(transaction);
+		if (!db.containsContact(txn, c))
+			throw new NoSuchContactException();
+		if (!db.containsVisibleMessage(txn, c, m)) return null;
+		Message message = db.getMessage(txn, m);
+		if (markAsSent) {
+			db.updateRetransmissionData(txn, c, m, maxLatency);
+			db.lowerRequestedFlag(txn, c, singletonList(m));
+			transaction.attach(new MessagesSentEvent(c, singletonList(m),
+					message.getRawLength()));
+		}
+		return message;
+	}
+
+	@Override
+	public Collection<MessageId> getUnackedMessagesToSend(
+			Transaction transaction, ContactId c) throws DbException {
 		T txn = unbox(transaction);
 		if (!db.containsContact(txn, c))
 			throw new NoSuchContactException();
 		return db.getUnackedMessagesToSend(txn, c);
 	}
 
+	@Override
+	public void resetUnackedMessagesToSend(Transaction transaction, ContactId c)
+			throws DbException {
+		T txn = unbox(transaction);
+		if (!db.containsContact(txn, c))
+			throw new NoSuchContactException();
+		db.resetUnackedMessagesToSend(txn, c);
+	}
+
 	@Override
 	public long getUnackedMessageBytesToSend(Transaction transaction,
 			ContactId c) throws DbException {
@@ -1060,6 +1080,20 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 		db.removeTransportKeys(txn, t, k);
 	}
 
+	@Override
+	public void setAckSent(Transaction transaction, ContactId c,
+			Collection<MessageId> acked) throws DbException {
+		if (transaction.isReadOnly()) throw new IllegalArgumentException();
+		T txn = unbox(transaction);
+		if (!db.containsContact(txn, c))
+			throw new NoSuchContactException();
+		List<MessageId> visible = new ArrayList<>(acked.size());
+		for (MessageId m : acked) {
+			if (db.containsVisibleMessage(txn, c, m)) visible.add(m);
+		}
+		db.lowerAckFlag(txn, c, visible);
+	}
+
 	@Override
 	public void setCleanupTimerDuration(Transaction transaction, MessageId m,
 			long duration) throws DbException {
@@ -1106,7 +1140,7 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 		if (old == INVISIBLE) db.addGroupVisibility(txn, c, g, v == SHARED);
 		else if (v == INVISIBLE) db.removeGroupVisibility(txn, c, g);
 		else db.setGroupVisibility(txn, c, g, v == SHARED);
-		List<ContactId> affected = Collections.singletonList(c);
+		List<ContactId> affected = singletonList(c);
 		transaction.attach(new GroupVisibilityUpdatedEvent(affected));
 	}
 
@@ -1154,6 +1188,28 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 		transaction.attach(new MessageStateChangedEvent(m, false, state));
 	}
 
+	@Override
+	public void setMessagesSent(Transaction transaction, ContactId c,
+			Collection<MessageId> sent, long maxLatency) throws DbException {
+		if (transaction.isReadOnly()) throw new IllegalArgumentException();
+		T txn = unbox(transaction);
+		if (!db.containsContact(txn, c))
+			throw new NoSuchContactException();
+		long totalLength = 0;
+		List<MessageId> visible = new ArrayList<>(sent.size());
+		for (MessageId m : sent) {
+			if (db.containsVisibleMessage(txn, c, m)) {
+				visible.add(m);
+				totalLength += db.getMessageLength(txn, m);
+				db.updateRetransmissionData(txn, c, m, maxLatency);
+			}
+		}
+		db.lowerRequestedFlag(txn, c, visible);
+		if (!visible.isEmpty()) {
+			transaction.attach(new MessagesSentEvent(c, visible, totalLength));
+		}
+	}
+
 	@Override
 	public void addMessageDependencies(Transaction transaction,
 			Message dependent, Collection<MessageId> dependencies)

bramble-core/src/main/java/org/briarproject/bramble/db/DatabaseConstants.java

@@ -2,8 +2,6 @@ package org.briarproject.bramble.db;
 
 import org.briarproject.bramble.api.settings.Settings;
 
-import static java.util.concurrent.TimeUnit.DAYS;
-
 interface DatabaseConstants {
 
 	/**
@@ -25,19 +23,6 @@ interface DatabaseConstants {
 	 */
 	String SCHEMA_VERSION_KEY = "schemaVersion";
 
-	/**
-	 * The {@link Settings} key under which the time of the last database
-	 * compaction is stored.
-	 */
-	String LAST_COMPACTED_KEY = "lastCompacted";
-
-	/**
-	 * The maximum time between database compactions in milliseconds. When the
-	 * database is opened it will be compacted if more than this amount of time
-	 * has passed since the last compaction.
-	 */
-	long MAX_COMPACTION_INTERVAL_MS = DAYS.toMillis(30);
-
 	/**
 	 * The {@link Settings} key under which the flag is stored indicating
 	 * whether the database is marked as dirty.

bramble-core/src/main/java/org/briarproject/bramble/db/H2Database.java

@@ -85,12 +85,17 @@ class H2Database extends JdbcDatabase {
 	public void close() throws DbException {
 		// H2 will close the database when the last connection closes
 		Connection c = null;
+		Statement s = null;
 		try {
 			c = createConnection();
-			super.closeAllConnections();
+			closeAllConnections();
 			setDirty(c, false);
+			s = c.createStatement();
+			s.execute("SHUTDOWN COMPACT");
+			s.close();
 			c.close();
 		} catch (SQLException e) {
+			tryToClose(s, LOG, WARNING);
 			tryToClose(c, LOG, WARNING);
 			throw new DbException(e);
 		}

bramble-core/src/main/java/org/briarproject/bramble/db/HyperSqlDatabase.java

@@ -79,11 +79,11 @@ class HyperSqlDatabase extends JdbcDatabase {
 		Connection c = null;
 		Statement s = null;
 		try {
-			super.closeAllConnections();
+			closeAllConnections();
 			c = createConnection();
 			setDirty(c, false);
 			s = c.createStatement();
-			s.executeQuery("SHUTDOWN");
+			s.executeQuery("SHUTDOWN COMPACT");
 			s.close();
 			c.close();
 		} catch (SQLException e) {
@@ -106,7 +106,7 @@ class HyperSqlDatabase extends JdbcDatabase {
 		Connection c = null;
 		Statement s = null;
 		try {
-			super.closeAllConnections();
+			closeAllConnections();
 			c = createConnection();
 			s = c.createStatement();
 			s.executeQuery("SHUTDOWN COMPACT");

bramble-core/src/main/java/org/briarproject/bramble/db/JdbcDatabase.java

@@ -51,7 +51,6 @@ import java.util.Collection;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.HashSet;
-import java.util.LinkedHashMap;
 import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
@@ -70,12 +69,14 @@ import static java.sql.Types.BOOLEAN;
 import static java.sql.Types.INTEGER;
 import static java.sql.Types.VARCHAR;
 import static java.util.Arrays.asList;
+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.db.DatabaseComponent.NO_CLEANUP_DEADLINE;
 import static org.briarproject.bramble.api.db.DatabaseComponent.TIMER_NOT_STARTED;
 import static org.briarproject.bramble.api.db.Metadata.REMOVE;
+import static org.briarproject.bramble.api.record.Record.RECORD_HEADER_BYTES;
 import static org.briarproject.bramble.api.sync.Group.Visibility.INVISIBLE;
 import static org.briarproject.bramble.api.sync.Group.Visibility.SHARED;
 import static org.briarproject.bramble.api.sync.Group.Visibility.VISIBLE;
@@ -85,8 +86,6 @@ import static org.briarproject.bramble.api.sync.validation.MessageState.PENDING;
 import static org.briarproject.bramble.api.sync.validation.MessageState.UNKNOWN;
 import static org.briarproject.bramble.db.DatabaseConstants.DB_SETTINGS_NAMESPACE;
 import static org.briarproject.bramble.db.DatabaseConstants.DIRTY_KEY;
-import static org.briarproject.bramble.db.DatabaseConstants.LAST_COMPACTED_KEY;
-import static org.briarproject.bramble.db.DatabaseConstants.MAX_COMPACTION_INTERVAL_MS;
 import static org.briarproject.bramble.db.DatabaseConstants.SCHEMA_VERSION_KEY;
 import static org.briarproject.bramble.db.ExponentialBackoff.calculateExpiry;
 import static org.briarproject.bramble.db.JdbcUtils.tryToClose;
@@ -102,7 +101,12 @@ import static org.briarproject.bramble.util.LogUtils.now;
 abstract class JdbcDatabase implements Database<Connection> {
 
 	// Package access for testing
-	static final int CODE_SCHEMA_VERSION = 49;
+	static final int CODE_SCHEMA_VERSION = 50;
+
+	/**
+	 * The maximum number of idle connections to keep open.
+	 */
+	private static final int MAX_CONNECTION_POOL_SIZE = 1;
 
 	// Time period offsets for incoming transport keys
 	private static final int OFFSET_PREV = -1;
@@ -252,7 +256,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 					+ " requested BOOLEAN NOT NULL,"
 					+ " expiry BIGINT NOT NULL,"
 					+ " txCount INT NOT NULL,"
-					+ " eta BIGINT NOT NULL,"
+					+ " maxLatency BIGINT," // Null if latency was reset
 					+ " PRIMARY KEY (messageId, contactId),"
 					+ " FOREIGN KEY (messageId)"
 					+ " REFERENCES messages (messageId)"
@@ -365,7 +369,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 	private final Condition connectionsChanged = connectionsLock.newCondition();
 
 	@GuardedBy("connectionsLock")
-	private final LinkedList<Connection> connections = new LinkedList<>();
+	private final LinkedList<Connection> connectionPool = new LinkedList<>();
 
 	@GuardedBy("connectionsLock")
 	private int openConnections = 0;
@@ -378,8 +382,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 			throws DbException, SQLException;
 
 	// Used exclusively during open to compact the database after schema
-	// migrations or after DatabaseConstants#MAX_COMPACTION_INTERVAL_MS has
+	// migrations or if the database was not shut down cleanly
-	// elapsed
 	protected abstract void compactAndClose() throws DbException;
 
 	JdbcDatabase(DatabaseTypes databaseTypes, MessageFactory messageFactory,
@@ -405,7 +408,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 			if (reopen) {
 				Settings s = getSettings(txn, DB_SETTINGS_NAMESPACE);
 				wasDirtyOnInitialisation = isDirty(s);
-				compact = migrateSchema(txn, s, listener) || isCompactionDue(s);
+				boolean migrated = migrateSchema(txn, s, listener);
+				compact = wasDirtyOnInitialisation || migrated;
 			} else {
 				wasDirtyOnInitialisation = false;
 				createTables(txn);
@@ -429,16 +433,11 @@ abstract class JdbcDatabase implements Database<Connection> {
 			compactAndClose();
 			logDuration(LOG, "Compacting database", start);
 			// Allow the next transaction to reopen the DB
-			synchronized (connectionsLock) {
+			connectionsLock.lock();
-				closed = false;
-			}
-			txn = startTransaction();
 			try {
-				storeLastCompacted(txn);
+				closed = false;
-				commitTransaction(txn);
+			} finally {
-			} catch (DbException e) {
+				connectionsLock.unlock();
-				abortTransaction(txn);
-				throw e;
 			}
 		}
 	}
@@ -499,18 +498,11 @@ abstract class JdbcDatabase implements Database<Connection> {
 				new Migration45_46(),
 				new Migration46_47(dbTypes),
 				new Migration47_48(),
-				new Migration48_49()
+				new Migration48_49(),
+				new Migration49_50()
 		);
 	}
 
-	private boolean isCompactionDue(Settings s) {
-		long lastCompacted = s.getLong(LAST_COMPACTED_KEY, 0);
-		long elapsed = clock.currentTimeMillis() - lastCompacted;
-		if (LOG.isLoggable(INFO))
-			LOG.info(elapsed + " ms since last compaction");
-		return elapsed > MAX_COMPACTION_INTERVAL_MS;
-	}
-
 	private void storeSchemaVersion(Connection txn, int version)
 			throws DbException {
 		Settings s = new Settings();
@@ -518,12 +510,6 @@ abstract class JdbcDatabase implements Database<Connection> {
 		mergeSettings(txn, s, DB_SETTINGS_NAMESPACE);
 	}
 
-	private void storeLastCompacted(Connection txn) throws DbException {
-		Settings s = new Settings();
-		s.putLong(LAST_COMPACTED_KEY, clock.currentTimeMillis());
-		mergeSettings(txn, s, DB_SETTINGS_NAMESPACE);
-	}
-
 	private boolean isDirty(Settings s) {
 		return s.getBoolean(DIRTY_KEY, false);
 	}
@@ -537,7 +523,6 @@ abstract class JdbcDatabase implements Database<Connection> {
 	private void initialiseSettings(Connection txn) throws DbException {
 		Settings s = new Settings();
 		s.putInt(SCHEMA_VERSION_KEY, CODE_SCHEMA_VERSION);
-		s.putLong(LAST_COMPACTED_KEY, clock.currentTimeMillis());
 		mergeSettings(txn, s, DB_SETTINGS_NAMESPACE);
 	}
 
@@ -592,7 +577,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 		connectionsLock.lock();
 		try {
 			if (closed) throw new DbClosedException();
-			txn = connections.poll();
+			txn = connectionPool.poll();
+			logConnectionCounts();
 		} finally {
 			connectionsLock.unlock();
 		}
@@ -603,7 +589,14 @@ abstract class JdbcDatabase implements Database<Connection> {
 				txn.setAutoCommit(false);
 				connectionsLock.lock();
 				try {
+					// The DB may have been closed since the check above
+					if (closed) {
+						tryToClose(txn, LOG, WARNING);
+						throw new DbClosedException();
+					}
 					openConnections++;
+					logConnectionCounts();
+					connectionsChanged.signalAll();
 				} finally {
 					connectionsLock.unlock();
 				}
@@ -614,67 +607,91 @@ abstract class JdbcDatabase implements Database<Connection> {
 		return txn;
 	}
 
-	@Override
+	@GuardedBy("connectionsLock")
-	public void abortTransaction(Connection txn) {
+	private void logConnectionCounts() {
-		try {
+		if (LOG.isLoggable(FINE)) {
-			txn.rollback();
+			LOG.fine(openConnections + " connections open, "
-			connectionsLock.lock();
+					+ connectionPool.size() + " in pool");
-			try {
-				connections.add(txn);
-				connectionsChanged.signalAll();
-			} finally {
-				connectionsLock.unlock();
-			}
-		} catch (SQLException e) {
-			// Try to close the connection
-			logException(LOG, WARNING, e);
-			tryToClose(txn, LOG, WARNING);
-			// Whatever happens, allow the database to close
-			connectionsLock.lock();
-			try {
-				openConnections--;
-				connectionsChanged.signalAll();
-			} finally {
-				connectionsLock.unlock();
-			}
 		}
 	}
 
 	@Override
-	public void commitTransaction(Connection txn) throws DbException {
+	public void abortTransaction(Connection txn) {
+		// The transaction may have been aborted due to an earlier exception,
+		// so close the connection rather than returning it to the pool
 		try {
-			txn.commit();
+			txn.rollback();
 		} catch (SQLException e) {
-			throw new DbException(e);
+			logException(LOG, WARNING, e);
 		}
+		closeConnection(txn);
+	}
+
+	private void closeConnection(Connection txn) {
+		tryToClose(txn, LOG, WARNING);
 		connectionsLock.lock();
 		try {
-			connections.add(txn);
+			openConnections--;
+			logConnectionCounts();
 			connectionsChanged.signalAll();
 		} finally {
 			connectionsLock.unlock();
 		}
 	}
 
-	void closeAllConnections() throws SQLException {
+	@Override
+	public void commitTransaction(Connection txn) throws DbException {
+		// If the transaction commits successfully then return the connection
+		// to the pool, otherwise close it
+		try {
+			txn.commit();
+			returnConnectionToPool(txn);
+		} catch (SQLException e) {
+			logException(LOG, WARNING, e);
+			closeConnection(txn);
+			throw new DbException(e);
+		}
+	}
+
+	private void returnConnectionToPool(Connection txn) {
+		boolean shouldClose;
+		connectionsLock.lock();
+		try {
+			shouldClose = connectionPool.size() >= MAX_CONNECTION_POOL_SIZE;
+			if (shouldClose) openConnections--;
+			else connectionPool.add(txn);
+			logConnectionCounts();
+			connectionsChanged.signalAll();
+		} finally {
+			connectionsLock.unlock();
+		}
+		if (shouldClose) tryToClose(txn, LOG, WARNING);
+	}
+
+	void closeAllConnections() {
 		boolean interrupted = false;
 		connectionsLock.lock();
 		try {
 			closed = true;
-			for (Connection c : connections) c.close();
+			for (Connection c : connectionPool) tryToClose(c, LOG, WARNING);
-			openConnections -= connections.size();
+			openConnections -= connectionPool.size();
-			connections.clear();
+			connectionPool.clear();
 			while (openConnections > 0) {
+				if (LOG.isLoggable(INFO)) {
+					LOG.info("Waiting for " + openConnections
+							+ " connections to be closed");
+				}
 				try {
 					connectionsChanged.await();
 				} catch (InterruptedException e) {
 					LOG.warning("Interrupted while closing connections");
 					interrupted = true;
 				}
-				for (Connection c : connections) c.close();
+				for (Connection c : connectionPool) tryToClose(c, LOG, WARNING);
-				openConnections -= connections.size();
+				openConnections -= connectionPool.size();
-				connections.clear();
+				connectionPool.clear();
 			}
+			LOG.info("All connections closed");
 		} finally {
 			connectionsLock.unlock();
 		}
@@ -917,9 +934,10 @@ abstract class JdbcDatabase implements Database<Connection> {
 		try {
 			String sql = "INSERT INTO statuses (messageId, contactId, groupId,"
 					+ " timestamp, length, state, groupShared, messageShared,"
-					+ " deleted, ack, seen, requested, expiry, txCount, eta)"
+					+ " deleted, ack, seen, requested, expiry, txCount,"
+					+ " maxLatency)"
 					+ " VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, FALSE, 0, 0,"
-					+ " 0)";
+					+ " NULL)";
 			ps = txn.prepareStatement(sql);
 			ps.setBytes(1, m.getBytes());
 			ps.setInt(2, c.getInt());
@@ -1153,17 +1171,17 @@ abstract class JdbcDatabase implements Database<Connection> {
 				ps.setInt(2, DELIVERED.getValue());
 			} else {
 				long now = clock.currentTimeMillis();
-				long eta = now + maxLatency;
 				sql = "SELECT NULL FROM statuses"
 						+ " WHERE contactId = ? AND state = ?"
 						+ " AND groupShared = TRUE AND messageShared = TRUE"
 						+ " AND deleted = FALSE AND seen = FALSE"
-						+ " AND (expiry <= ? OR eta > ?)";
+						+ " AND (expiry <= ? OR maxLatency IS NULL"
+						+ " OR ? < maxLatency)";
 				ps = txn.prepareStatement(sql);
 				ps.setInt(1, c.getInt());
 				ps.setInt(2, DELIVERED.getValue());
 				ps.setLong(3, now);
-				ps.setLong(4, eta);
+				ps.setLong(4, maxLatency);
 			}
 			rs = ps.executeQuery();
 			boolean messagesToSend = rs.next();
@@ -1899,6 +1917,31 @@ abstract class JdbcDatabase implements Database<Connection> {
 		}
 	}
 
+	@Override
+	public int getMessageLength(Connection txn, MessageId m)
+			throws DbException {
+		PreparedStatement ps = null;
+		ResultSet rs = null;
+		try {
+			String sql = "SELECT length from messages"
+					+ " WHERE messageId = ? AND state = ?";
+			ps = txn.prepareStatement(sql);
+			ps.setBytes(1, m.getBytes());
+			ps.setInt(2, DELIVERED.getValue());
+			rs = ps.executeQuery();
+			if (!rs.next()) throw new DbStateException();
+			int length = rs.getInt(1);
+			if (rs.next()) throw new DbStateException();
+			rs.close();
+			ps.close();
+			return length;
+		} catch (SQLException e) {
+			tryToClose(rs, LOG, WARNING);
+			tryToClose(ps, LOG, WARNING);
+			throw new DbException(e);
+		}
+	}
+
 	@Override
 	public Map<MessageId, Metadata> getMessageMetadata(Connection txn,
 			GroupId g) throws DbException {
@@ -2191,7 +2234,6 @@ abstract class JdbcDatabase implements Database<Connection> {
 	public Collection<MessageId> getMessagesToOffer(Connection txn,
 			ContactId c, int maxMessages, long maxLatency) throws DbException {
 		long now = clock.currentTimeMillis();
-		long eta = now + maxLatency;
 		PreparedStatement ps = null;
 		ResultSet rs = null;
 		try {
@@ -2200,13 +2242,14 @@ abstract class JdbcDatabase implements Database<Connection> {
 					+ " AND groupShared = TRUE AND messageShared = TRUE"
 					+ " AND deleted = FALSE"
 					+ " AND seen = FALSE AND requested = FALSE"
-					+ " AND (expiry <= ? OR eta > ?)"
+					+ " AND (expiry <= ? OR maxLatency IS NULL"
+					+ " OR ? < maxLatency)"
 					+ " ORDER BY timestamp LIMIT ?";
 			ps = txn.prepareStatement(sql);
 			ps.setInt(1, c.getInt());
 			ps.setInt(2, DELIVERED.getValue());
 			ps.setLong(3, now);
-			ps.setLong(4, eta);
+			ps.setLong(4, maxLatency);
 			ps.setInt(5, maxMessages);
 			rs = ps.executeQuery();
 			List<MessageId> ids = new ArrayList<>();
@@ -2247,10 +2290,9 @@ abstract class JdbcDatabase implements Database<Connection> {
 	}
 
 	@Override
-	public Collection<MessageId> getMessagesToSend(Connection txn, ContactId c,
+	public Collection<MessageId> getMessagesToSend(Connection txn,
-			int maxLength, long maxLatency) throws DbException {
+			ContactId c, long capacity, long maxLatency) throws DbException {
 		long now = clock.currentTimeMillis();
-		long eta = now + maxLatency;
 		PreparedStatement ps = null;
 		ResultSet rs = null;
 		try {
@@ -2259,21 +2301,21 @@ abstract class JdbcDatabase implements Database<Connection> {
 					+ " AND groupShared = TRUE AND messageShared = TRUE"
 					+ " AND deleted = FALSE"
 					+ " AND seen = FALSE"
-					+ " AND (expiry <= ? OR eta > ?)"
+					+ " AND (expiry <= ? OR maxLatency IS NULL"
+					+ " OR ? < maxLatency)"
 					+ " ORDER BY timestamp";
 			ps = txn.prepareStatement(sql);
 			ps.setInt(1, c.getInt());
 			ps.setInt(2, DELIVERED.getValue());
 			ps.setLong(3, now);
-			ps.setLong(4, eta);
+			ps.setLong(4, maxLatency);
 			rs = ps.executeQuery();
 			List<MessageId> ids = new ArrayList<>();
-			int total = 0;
 			while (rs.next()) {
 				int length = rs.getInt(1);
-				if (total + length > maxLength) break;
+				if (capacity < RECORD_HEADER_BYTES + length) break;
 				ids.add(new MessageId(rs.getBytes(2)));
-				total += length;
+				capacity -= RECORD_HEADER_BYTES + length;
 			}
 			rs.close();
 			ps.close();
@@ -2286,12 +2328,12 @@ abstract class JdbcDatabase implements Database<Connection> {
 	}
 
 	@Override
-	public Map<MessageId, Integer> getUnackedMessagesToSend(Connection txn,
+	public Collection<MessageId> getUnackedMessagesToSend(Connection txn,
 			ContactId c) throws DbException {
 		PreparedStatement ps = null;
 		ResultSet rs = null;
 		try {
-			String sql = "SELECT length, messageId FROM statuses"
+			String sql = "SELECT messageId FROM statuses"
 					+ " WHERE contactId = ? AND state = ?"
 					+ " AND groupShared = TRUE AND messageShared = TRUE"
 					+ " AND deleted = FALSE AND seen = FALSE"
@@ -2300,15 +2342,11 @@ abstract class JdbcDatabase implements Database<Connection> {
 			ps.setInt(1, c.getInt());
 			ps.setInt(2, DELIVERED.getValue());
 			rs = ps.executeQuery();
-			Map<MessageId, Integer> results = new LinkedHashMap<>();
+			List<MessageId> ids = new ArrayList<>();
-			while (rs.next()) {
+			while (rs.next()) ids.add(new MessageId(rs.getBytes(1)));
-				int length = rs.getInt(1);
-				MessageId id = new MessageId(rs.getBytes(2));
-				results.put(id, length);
-			}
 			rs.close();
 			ps.close();
-			return results;
+			return ids;
 		} catch (SQLException e) {
 			tryToClose(rs, LOG, WARNING);
 			tryToClose(ps, LOG, WARNING);
@@ -2421,6 +2459,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 				MessageId m = new MessageId(rs.getBytes(1));
 				GroupId g = new GroupId(rs.getBytes(2));
 				Collection<MessageId> messageIds = ids.get(g);
+				//noinspection Java8MapApi
 				if (messageIds == null) {
 					messageIds = new ArrayList<>();
 					ids.put(g, messageIds);
@@ -2547,9 +2586,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 
 	@Override
 	public Collection<MessageId> getRequestedMessagesToSend(Connection txn,
-			ContactId c, int maxLength, long maxLatency) throws DbException {
+			ContactId c, long capacity, long maxLatency) throws DbException {
 		long now = clock.currentTimeMillis();
-		long eta = now + maxLatency;
 		PreparedStatement ps = null;
 		ResultSet rs = null;
 		try {
@@ -2558,21 +2596,21 @@ abstract class JdbcDatabase implements Database<Connection> {
 					+ " AND groupShared = TRUE AND messageShared = TRUE"
 					+ " AND deleted = FALSE"
 					+ " AND seen = FALSE AND requested = TRUE"
-					+ " AND (expiry <= ? OR eta > ?)"
+					+ " AND (expiry <= ? OR maxLatency IS NULL"
+					+ " OR ? < maxLatency)"
 					+ " ORDER BY timestamp";
 			ps = txn.prepareStatement(sql);
 			ps.setInt(1, c.getInt());
 			ps.setInt(2, DELIVERED.getValue());
 			ps.setLong(3, now);
-			ps.setLong(4, eta);
+			ps.setLong(4, maxLatency);
 			rs = ps.executeQuery();
 			List<MessageId> ids = new ArrayList<>();
-			int total = 0;
 			while (rs.next()) {
 				int length = rs.getInt(1);
-				if (total + length > maxLength) break;
+				if (capacity < RECORD_HEADER_BYTES + length) break;
 				ids.add(new MessageId(rs.getBytes(2)));
-				total += length;
+				capacity -= RECORD_HEADER_BYTES + length;
 			}
 			rs.close();
 			ps.close();
@@ -2726,6 +2764,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 				ContactId c = new ContactId(rs.getInt(1));
 				TransportId t = new TransportId(rs.getString(2));
 				Collection<TransportId> transportIds = ids.get(c);
+				//noinspection Java8MapApi
 				if (transportIds == null) {
 					transportIds = new ArrayList<>();
 					ids.put(c, transportIds);
@@ -3290,6 +3329,30 @@ abstract class JdbcDatabase implements Database<Connection> {
 		}
 	}
 
+	@Override
+	public void resetUnackedMessagesToSend(Connection txn, ContactId c)
+			throws DbException {
+		PreparedStatement ps = null;
+		try {
+			String sql = "UPDATE statuses SET expiry = 0, txCount = 0,"
+					+ " maxLatency = NULL"
+					+ " WHERE contactId = ? AND state = ?"
+					+ " AND groupShared = TRUE AND messageShared = TRUE"
+					+ " AND deleted = FALSE AND seen = FALSE";
+			ps = txn.prepareStatement(sql);
+			ps.setInt(1, c.getInt());
+			ps.setInt(2, DELIVERED.getValue());
+			int affected = ps.executeUpdate();
+			if (affected < 0) {
+				throw new DbStateException();
+			}
+			ps.close();
+		} catch (SQLException e) {
+			tryToClose(ps, LOG, WARNING);
+			throw new DbException(e);
+		}
+	}
+
 	@Override
 	public void setCleanupTimerDuration(Connection txn, MessageId m,
 			long duration) throws DbException {
@@ -3617,8 +3680,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 	}
 
 	@Override
-	public void updateExpiryTimeAndEta(Connection txn, ContactId c, MessageId m,
+	public void updateRetransmissionData(Connection txn, ContactId c,
-			long maxLatency) throws DbException {
+			MessageId m, long maxLatency) throws DbException {
 		PreparedStatement ps = null;
 		ResultSet rs = null;
 		try {
@@ -3634,13 +3697,12 @@ abstract class JdbcDatabase implements Database<Connection> {
 			rs.close();
 			ps.close();
 			sql = "UPDATE statuses"
-					+ " SET expiry = ?, txCount = txCount + 1, eta = ?"
+					+ " SET expiry = ?, txCount = txCount + 1, maxLatency = ?"
 					+ " WHERE messageId = ? AND contactId = ?";
 			ps = txn.prepareStatement(sql);
 			long now = clock.currentTimeMillis();
-			long eta = now + maxLatency;
 			ps.setLong(1, calculateExpiry(now, maxLatency, txCount));
-			ps.setLong(2, eta);
+			ps.setLong(2, maxLatency);
 			ps.setBytes(3, m.getBytes());
 			ps.setInt(4, c.getInt());
 			int affected = ps.executeUpdate();

bramble-core/src/main/java/org/briarproject/bramble/db/Migration49_50.java

@@ -0,0 +1,45 @@
+package org.briarproject.bramble.db;
+
+import org.briarproject.bramble.api.db.DbException;
+
+import java.sql.Connection;
+import java.sql.SQLException;
+import java.sql.Statement;
+import java.util.logging.Logger;
+
+import static java.util.logging.Level.WARNING;
+import static java.util.logging.Logger.getLogger;
+import static org.briarproject.bramble.db.JdbcUtils.tryToClose;
+
+class Migration49_50 implements Migration<Connection> {
+
+	private static final Logger LOG = getLogger(Migration49_50.class.getName());
+
+	@Override
+	public int getStartVersion() {
+		return 49;
+	}
+
+	@Override
+	public int getEndVersion() {
+		return 50;
+	}
+
+	@Override
+	public void migrate(Connection txn) throws DbException {
+		Statement s = null;
+		try {
+			s = txn.createStatement();
+			s.execute("ALTER TABLE statuses"
+					+ " ALTER COLUMN eta"
+					+ " RENAME TO maxLatency");
+			s.execute("ALTER TABLE statuses"
+					+ " ALTER COLUMN maxLatency"
+					+ " SET NULL");
+			s.execute("UPDATE statuses SET maxLatency = NULL");
+		} catch (SQLException e) {
+			tryToClose(s, LOG, WARNING);
+			throw new DbException(e);
+		}
+	}
+}

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

@@ -1,18 +1,49 @@
 package org.briarproject.bramble.io;
 
+import org.briarproject.bramble.api.WeakSingletonProvider;
 import org.briarproject.bramble.api.io.TimeoutMonitor;
 
+import javax.annotation.Nonnull;
 import javax.inject.Singleton;
+import javax.net.SocketFactory;
 
 import dagger.Module;
 import dagger.Provides;
+import okhttp3.Dns;
+import okhttp3.OkHttpClient;
+
+import static java.util.concurrent.TimeUnit.MILLISECONDS;
 
 @Module
 public class IoModule {
 
+	private static final int CONNECT_TIMEOUT = 60_000; // Milliseconds
+
 	@Provides
 	@Singleton
 	TimeoutMonitor provideTimeoutMonitor(TimeoutMonitorImpl timeoutMonitor) {
 		return timeoutMonitor;
 	}
+
+	// Share an HTTP client instance between requests where possible, while
+	// allowing the client to be garbage-collected between requests. The
+	// provider keeps a weak reference to the last client instance and reuses
+	// the instance until it gets garbage-collected. See
+	// https://medium.com/@leandromazzuquini/if-you-are-using-okhttp-you-should-know-this-61d68e065a2b
+	@Provides
+	@Singleton
+	WeakSingletonProvider<OkHttpClient> provideOkHttpClientProvider(
+			SocketFactory torSocketFactory, Dns noDnsLookups) {
+		return new WeakSingletonProvider<OkHttpClient>() {
+			@Override
+			@Nonnull
+			public OkHttpClient createInstance() {
+				return new OkHttpClient.Builder()
+						.socketFactory(torSocketFactory)
+						.dns(noDnsLookups) // Don't make local DNS lookups
+						.connectTimeout(CONNECT_TIMEOUT, MILLISECONDS)
+						.build();
+			}
+		};
+	}
 }

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

@@ -1,10 +1,10 @@
 package org.briarproject.bramble.io;
 
+import org.briarproject.bramble.api.Cancellable;
 import org.briarproject.bramble.api.io.TimeoutMonitor;
 import org.briarproject.bramble.api.lifecycle.IoExecutor;
 import org.briarproject.bramble.api.system.Clock;
 import org.briarproject.bramble.api.system.TaskScheduler;
-import org.briarproject.bramble.api.system.TaskScheduler.Cancellable;
 import org.briarproject.bramble.api.system.Wakeful;
 
 import java.io.IOException;

bramble-core/src/main/java/org/briarproject/bramble/mailbox/ApiCall.java

@@ -0,0 +1,21 @@
+package org.briarproject.bramble.mailbox;
+
+import org.briarproject.bramble.api.lifecycle.IoExecutor;
+import org.briarproject.bramble.mailbox.MailboxApi.TolerableFailureException;
+
+/**
+ * An interface for calling an API endpoint with the option to retry the call.
+ */
+interface ApiCall {
+
+	/**
+	 * This method makes a synchronous call to an API endpoint and returns
+	 * true if the call should be retried, in which case the method may be
+	 * called again on the same {@link ApiCall} instance after a delay.
+	 *
+	 * @return True if the API call needs to be retried, or false if the API
+	 * call succeeded or {@link TolerableFailureException failed tolerably}.
+	 */
+	@IoExecutor
+	boolean callApi();
+}

bramble-core/src/main/java/org/briarproject/bramble/mailbox/ConnectivityChecker.java

@@ -0,0 +1,32 @@
+package org.briarproject.bramble.mailbox;
+
+import org.briarproject.bramble.api.mailbox.MailboxProperties;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import javax.annotation.concurrent.ThreadSafe;
+
+/**
+ * An interface for checking whether a mailbox is reachable.
+ */
+@ThreadSafe
+@NotNullByDefault
+interface ConnectivityChecker {
+
+	/**
+	 * Destroys the checker. Any current connectivity check is cancelled.
+	 */
+	void destroy();
+
+	/**
+	 * Starts a connectivity check if needed and calls the given observer when
+	 * the check succeeds. If a check is already running then the observer is
+	 * called when the check succeeds. If a connectivity check has recently
+	 * succeeded then the observer is called immediately.
+	 */
+	void checkConnectivity(MailboxProperties properties,
+			ConnectivityObserver o);
+
+	interface ConnectivityObserver {
+		void onConnectivityCheckSucceeded();
+	}
+}

bramble-core/src/main/java/org/briarproject/bramble/mailbox/ConnectivityCheckerImpl.java

@@ -0,0 +1,111 @@
+package org.briarproject.bramble.mailbox;
+
+import org.briarproject.bramble.api.Cancellable;
+import org.briarproject.bramble.api.mailbox.MailboxProperties;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.system.Clock;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import javax.annotation.Nullable;
+import javax.annotation.concurrent.GuardedBy;
+import javax.annotation.concurrent.ThreadSafe;
+
+@ThreadSafe
+@NotNullByDefault
+abstract class ConnectivityCheckerImpl implements ConnectivityChecker {
+
+	/**
+	 * If no more than this much time has elapsed since the last connectivity
+	 * check succeeded, consider the result to be fresh and don't check again.
+	 * <p>
+	 * Package access for testing.
+	 */
+	static final long CONNECTIVITY_CHECK_FRESHNESS_MS = 10_000;
+
+	private final Object lock = new Object();
+
+	protected final Clock clock;
+	private final MailboxApiCaller mailboxApiCaller;
+
+	@GuardedBy("lock")
+	private boolean destroyed = false;
+
+	@GuardedBy("lock")
+	@Nullable
+	private Cancellable connectivityCheck = null;
+
+	@GuardedBy("lock")
+	private long lastConnectivityCheckSucceeded = 0;
+
+	@GuardedBy("lock")
+	private final List<ConnectivityObserver> connectivityObservers =
+			new ArrayList<>();
+
+	/**
+	 * Creates an {@link ApiCall} for checking whether the mailbox is
+	 * reachable. The {@link ApiCall} should call
+	 * {@link #onConnectivityCheckSucceeded(long)} if the check succeeds.
+	 */
+	abstract ApiCall createConnectivityCheckTask(MailboxProperties properties);
+
+	ConnectivityCheckerImpl(Clock clock, MailboxApiCaller mailboxApiCaller) {
+		this.clock = clock;
+		this.mailboxApiCaller = mailboxApiCaller;
+	}
+
+	@Override
+	public void destroy() {
+		synchronized (lock) {
+			destroyed = true;
+			connectivityObservers.clear();
+			if (connectivityCheck != null) {
+				connectivityCheck.cancel();
+				connectivityCheck = null;
+			}
+		}
+	}
+
+	@Override
+	public void checkConnectivity(MailboxProperties properties,
+			ConnectivityObserver o) {
+		boolean callNow = false;
+		synchronized (lock) {
+			if (destroyed) return;
+			if (connectivityCheck == null) {
+				// No connectivity check is running
+				long now = clock.currentTimeMillis();
+				if (now - lastConnectivityCheckSucceeded
+						> CONNECTIVITY_CHECK_FRESHNESS_MS) {
+					// The last connectivity check is stale, start a new one
+					connectivityObservers.add(o);
+					ApiCall task =
+							createConnectivityCheckTask(properties);
+					connectivityCheck = mailboxApiCaller.retryWithBackoff(task);
+				} else {
+					// The last connectivity check is fresh
+					callNow = true;
+				}
+			} else {
+				// A connectivity check is running, wait for it to succeed
+				connectivityObservers.add(o);
+			}
+		}
+		if (callNow) o.onConnectivityCheckSucceeded();
+	}
+
+	protected void onConnectivityCheckSucceeded(long now) {
+		List<ConnectivityObserver> observers;
+		synchronized (lock) {
+			if (destroyed) return;
+			connectivityCheck = null;
+			lastConnectivityCheckSucceeded = now;
+			observers = new ArrayList<>(connectivityObservers);
+			connectivityObservers.clear();
+		}
+		for (ConnectivityObserver o : observers) {
+			o.onConnectivityCheckSucceeded();
+		}
+	}
+}

bramble-core/src/main/java/org/briarproject/bramble/mailbox/ContactMailboxConnectivityChecker.java

@@ -0,0 +1,39 @@
+package org.briarproject.bramble.mailbox;
+
+import org.briarproject.bramble.api.mailbox.MailboxProperties;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.system.Clock;
+import org.briarproject.bramble.mailbox.MailboxApi.ApiException;
+
+import java.io.IOException;
+
+import javax.annotation.concurrent.ThreadSafe;
+
+@ThreadSafe
+@NotNullByDefault
+class ContactMailboxConnectivityChecker extends ConnectivityCheckerImpl {
+
+	private final MailboxApi mailboxApi;
+
+	ContactMailboxConnectivityChecker(Clock clock,
+			MailboxApiCaller mailboxApiCaller, MailboxApi mailboxApi) {
+		super(clock, mailboxApiCaller);
+		this.mailboxApi = mailboxApi;
+	}
+
+	@Override
+	ApiCall createConnectivityCheckTask(MailboxProperties properties) {
+		if (properties.isOwner()) throw new IllegalArgumentException();
+		return new SimpleApiCall() {
+			@Override
+			void tryToCallApi() throws IOException, ApiException {
+				if (!mailboxApi.checkStatus(properties)) {
+					throw new ApiException();
+				}
+				// Call the observers and cache the result
+				onConnectivityCheckSucceeded(clock.currentTimeMillis());
+			}
+		};
+	}
+
+}

bramble-core/src/main/java/org/briarproject/bramble/mailbox/MailboxApi.java

@@ -0,0 +1,193 @@
+package org.briarproject.bramble.mailbox;
+
+import com.fasterxml.jackson.databind.annotation.JsonSerialize;
+
+import org.briarproject.bramble.api.contact.ContactId;
+import org.briarproject.bramble.api.mailbox.MailboxAuthToken;
+import org.briarproject.bramble.api.mailbox.MailboxFileId;
+import org.briarproject.bramble.api.mailbox.MailboxFolderId;
+import org.briarproject.bramble.api.mailbox.MailboxProperties;
+import org.briarproject.bramble.api.mailbox.MailboxUpdateManager;
+import org.briarproject.bramble.api.mailbox.MailboxVersion;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import java.io.File;
+import java.io.IOException;
+import java.util.Collection;
+import java.util.List;
+
+import javax.annotation.Nonnull;
+import javax.annotation.concurrent.Immutable;
+
+import static java.util.Collections.singletonList;
+
+@NotNullByDefault
+interface MailboxApi {
+
+	/**
+	 * Mailbox API versions that we support as a client. This is reported to our
+	 * contacts by {@link MailboxUpdateManager}.
+	 */
+	List<MailboxVersion> CLIENT_SUPPORTS = singletonList(
+			new MailboxVersion(1, 0));
+
+	List<MailboxVersion> getServerSupports(MailboxProperties properties)
+			throws IOException, ApiException;
+
+	/**
+	 * Sets up the mailbox with the setup token.
+	 *
+	 * @param properties MailboxProperties with the setup token
+	 * @return the owner token
+	 * @throws ApiException for 401 response.
+	 */
+	MailboxProperties setup(MailboxProperties properties)
+			throws IOException, ApiException;
+
+	/**
+	 * Checks the status of the mailbox.
+	 *
+	 * @return true if the status is OK, false otherwise.
+	 * @throws ApiException for 401 response.
+	 */
+	boolean checkStatus(MailboxProperties properties)
+			throws IOException, ApiException;
+
+	/**
+	 * Unpairs Briar and the mailbox (owner only).
+	 * Resets mailbox state to that after first install
+	 * (e.g. removes all stored files as well).
+	 */
+	void wipeMailbox(MailboxProperties properties)
+			throws IOException, ApiException;
+
+	/**
+	 * Adds a new contact to the mailbox.
+	 *
+	 * @throws TolerableFailureException if response code is 409
+	 * (contact was already added).
+	 */
+	void addContact(MailboxProperties properties, MailboxContact contact)
+			throws IOException, ApiException, TolerableFailureException;
+
+	/**
+	 * Deletes a contact from the mailbox.
+	 * This should get called after a contact was removed from Briar.
+	 *
+	 * @throws TolerableFailureException if response code is 404
+	 * (contact probably was already deleted).
+	 */
+	void deleteContact(MailboxProperties properties, ContactId contactId)
+			throws IOException, ApiException, TolerableFailureException;
+
+	/**
+	 * Gets a list of {@link ContactId}s from the mailbox.
+	 * These are the contacts that the mailbox already knows about.
+	 */
+	Collection<ContactId> getContacts(MailboxProperties properties)
+			throws IOException, ApiException;
+
+	/**
+	 * Used by contacts to send files to the owner
+	 * and by the owner to send files to contacts.
+	 * <p>
+	 * The owner can add files to the contacts' inboxes
+	 * and the contacts can add files to their own outbox.
+	 */
+	void addFile(MailboxProperties properties, MailboxFolderId folderId,
+			File file) throws IOException, ApiException;
+
+	/**
+	 * Used by owner and contacts to list their files to retrieve.
+	 * <p>
+	 * Returns 200 OK with the list of files in JSON.
+	 */
+	List<MailboxFile> getFiles(MailboxProperties properties,
+			MailboxFolderId folderId) throws IOException, ApiException;
+
+	/**
+	 * Used by owner and contacts to retrieve a file.
+	 * <p>
+	 * Returns 200 OK if successful with the files' raw bytes
+	 * in the response body.
+	 *
+	 * @param file the empty file the response bytes will be written into.
+	 */
+	void getFile(MailboxProperties properties, MailboxFolderId folderId,
+			MailboxFileId fileId, File file) throws IOException, ApiException;
+
+	/**
+	 * Used by owner and contacts to delete files.
+	 * <p>
+	 * Returns 200 OK (no exception) if deletion was successful.
+	 *
+	 * @throws TolerableFailureException on 404 response,
+	 * because file was most likely deleted already.
+	 */
+	void deleteFile(MailboxProperties properties, MailboxFolderId folderId,
+			MailboxFileId fileId)
+			throws IOException, ApiException, TolerableFailureException;
+
+	/**
+	 * Lists all contact outboxes that have files available
+	 * for the owner to download.
+	 *
+	 * @return a list of folder names
+	 * to be used with {@link #getFiles(MailboxProperties, MailboxFolderId)}.
+	 * @throws IllegalArgumentException if used by non-owner.
+	 */
+	List<MailboxFolderId> getFolders(MailboxProperties properties)
+			throws IOException, ApiException;
+
+	@Immutable
+	@JsonSerialize
+	class MailboxContact {
+		public final int contactId;
+		public final MailboxAuthToken token;
+		public final MailboxFolderId inboxId, outboxId;
+
+		MailboxContact(ContactId contactId,
+				MailboxAuthToken token,
+				MailboxFolderId inboxId,
+				MailboxFolderId outboxId) {
+			this.contactId = contactId.getInt();
+			this.token = token;
+			this.inboxId = inboxId;
+			this.outboxId = outboxId;
+		}
+	}
+
+	@JsonSerialize
+	class MailboxFile implements Comparable<MailboxFile> {
+		public final MailboxFileId name;
+		public final long time;
+
+		public MailboxFile(MailboxFileId name, long time) {
+			this.name = name;
+			this.time = time;
+		}
+
+		@Override
+		public int compareTo(@Nonnull MailboxApi.MailboxFile mailboxFile) {
+			//noinspection UseCompareMethod
+			return time < mailboxFile.time ? -1 :
+					(time == mailboxFile.time ? 0 : 1);
+		}
+	}
+
+	@Immutable
+	class ApiException extends Exception {
+	}
+
+	@Immutable
+	class MailboxAlreadyPairedException extends ApiException {
+	}
+
+	/**
+	 * A failure that does not need to be retried,
+	 * e.g. when adding a contact that already exists.
+	 */
+	@Immutable
+	class TolerableFailureException extends Exception {
+	}
+}

bramble-core/src/main/java/org/briarproject/bramble/mailbox/MailboxApiCaller.java

@@ -0,0 +1,32 @@
+package org.briarproject.bramble.mailbox;
+
+import org.briarproject.bramble.api.Cancellable;
+import org.briarproject.bramble.api.lifecycle.IoExecutor;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import static java.util.concurrent.TimeUnit.DAYS;
+import static java.util.concurrent.TimeUnit.MINUTES;
+
+@NotNullByDefault
+interface MailboxApiCaller {
+
+	/**
+	 * The minimum interval between retries in milliseconds.
+	 */
+	long MIN_RETRY_INTERVAL_MS = MINUTES.toMillis(1);
+
+	/**
+	 * The maximum interval between retries in milliseconds.
+	 */
+	long MAX_RETRY_INTERVAL_MS = DAYS.toMillis(1);
+
+	/**
+	 * Asynchronously calls the given API call on the {@link IoExecutor},
+	 * automatically retrying at increasing intervals until the API call
+	 * returns false or retries are cancelled.
+	 *
+	 * @return A {@link Cancellable} that can be used to cancel any future
+	 * retries.
+	 */
+	Cancellable retryWithBackoff(ApiCall apiCall);
+}

bramble-core/src/main/java/org/briarproject/bramble/mailbox/MailboxApiCallerImpl.java

@@ -0,0 +1,98 @@
+package org.briarproject.bramble.mailbox;
+
+import org.briarproject.bramble.api.Cancellable;
+import org.briarproject.bramble.api.lifecycle.IoExecutor;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.system.TaskScheduler;
+
+import java.util.concurrent.Executor;
+
+import javax.annotation.Nullable;
+import javax.annotation.concurrent.GuardedBy;
+import javax.annotation.concurrent.Immutable;
+import javax.inject.Inject;
+
+import static java.lang.Math.min;
+import static java.util.concurrent.TimeUnit.MILLISECONDS;
+
+@Immutable
+@NotNullByDefault
+class MailboxApiCallerImpl implements MailboxApiCaller {
+
+	private final TaskScheduler taskScheduler;
+	private final Executor ioExecutor;
+
+	@Inject
+	MailboxApiCallerImpl(TaskScheduler taskScheduler,
+			@IoExecutor Executor ioExecutor) {
+		this.taskScheduler = taskScheduler;
+		this.ioExecutor = ioExecutor;
+	}
+
+	@Override
+	public Cancellable retryWithBackoff(ApiCall apiCall) {
+		Task task = new Task(apiCall);
+		task.start();
+		return task;
+	}
+
+	private class Task implements Cancellable {
+
+		private final ApiCall apiCall;
+		private final Object lock = new Object();
+
+		@GuardedBy("lock")
+		@Nullable
+		private Cancellable scheduledTask = null;
+
+		@GuardedBy("lock")
+		private boolean cancelled = false;
+
+		@GuardedBy("lock")
+		private long retryIntervalMs = MIN_RETRY_INTERVAL_MS;
+
+		private Task(ApiCall apiCall) {
+			this.apiCall = apiCall;
+		}
+
+		private void start() {
+			synchronized (lock) {
+				if (cancelled) throw new AssertionError();
+				ioExecutor.execute(this::callApi);
+			}
+		}
+
+		@IoExecutor
+		private void callApi() {
+			synchronized (lock) {
+				if (cancelled) return;
+			}
+			// The call returns true if we should retry
+			if (apiCall.callApi()) {
+				synchronized (lock) {
+					if (cancelled) return;
+					scheduledTask = taskScheduler.schedule(this::callApi,
+							ioExecutor, retryIntervalMs, MILLISECONDS);
+					// Increase the retry interval each time we retry
+					retryIntervalMs =
+							min(MAX_RETRY_INTERVAL_MS, retryIntervalMs * 2);
+				}
+			} else {
+				synchronized (lock) {
+					scheduledTask = null;
+				}
+			}
+		}
+
+		@Override
+		public void cancel() {
+			Cancellable scheduledTask;
+			synchronized (lock) {
+				cancelled = true;
+				scheduledTask = this.scheduledTask;
+				this.scheduledTask = null;
+			}
+			if (scheduledTask != null) scheduledTask.cancel();
+		}
+	}
+}

bramble-core/src/main/java/org/briarproject/bramble/mailbox/MailboxApiImpl.java

@@ -0,0 +1,342 @@
+package org.briarproject.bramble.mailbox;
+
+import com.fasterxml.jackson.core.JacksonException;
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.json.JsonMapper;
+import com.fasterxml.jackson.databind.node.ArrayNode;
+import com.fasterxml.jackson.databind.node.ObjectNode;
+
+import org.briarproject.bramble.api.WeakSingletonProvider;
+import org.briarproject.bramble.api.contact.ContactId;
+import org.briarproject.bramble.api.mailbox.InvalidMailboxIdException;
+import org.briarproject.bramble.api.mailbox.MailboxAuthToken;
+import org.briarproject.bramble.api.mailbox.MailboxFileId;
+import org.briarproject.bramble.api.mailbox.MailboxFolderId;
+import org.briarproject.bramble.api.mailbox.MailboxId;
+import org.briarproject.bramble.api.mailbox.MailboxProperties;
+import org.briarproject.bramble.api.mailbox.MailboxVersion;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import java.io.File;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.List;
+
+import javax.inject.Inject;
+
+import okhttp3.MediaType;
+import okhttp3.OkHttpClient;
+import okhttp3.Request;
+import okhttp3.RequestBody;
+import okhttp3.Response;
+import okhttp3.ResponseBody;
+
+import static com.fasterxml.jackson.databind.MapperFeature.BLOCK_UNSAFE_POLYMORPHIC_BASE_TYPES;
+import static java.util.Objects.requireNonNull;
+import static okhttp3.internal.Util.EMPTY_REQUEST;
+import static org.briarproject.bramble.util.IoUtils.copyAndClose;
+
+@NotNullByDefault
+class MailboxApiImpl implements MailboxApi {
+
+	private final WeakSingletonProvider<OkHttpClient> httpClientProvider;
+	private final JsonMapper mapper = JsonMapper.builder()
+			.enable(BLOCK_UNSAFE_POLYMORPHIC_BASE_TYPES)
+			.build();
+	private static final MediaType JSON =
+			requireNonNull(MediaType.parse("application/json; charset=utf-8"));
+	private static final MediaType FILE =
+			requireNonNull(MediaType.parse("application/octet-stream"));
+
+	@Inject
+	MailboxApiImpl(WeakSingletonProvider<OkHttpClient> httpClientProvider) {
+		this.httpClientProvider = httpClientProvider;
+	}
+
+	@Override
+	public List<MailboxVersion> getServerSupports(MailboxProperties properties)
+			throws IOException, ApiException {
+		if (!properties.isOwner()) throw new IllegalArgumentException();
+		Response response = sendGetRequest(properties, "/versions");
+		if (response.code() != 200) throw new ApiException();
+
+		ResponseBody body = response.body();
+		if (body == null) throw new ApiException();
+		try {
+			JsonNode node = mapper.readTree(body.string());
+			return parseServerSupports(node);
+		} catch (JacksonException e) {
+			throw new ApiException();
+		}
+	}
+
+	@Override
+	public MailboxProperties setup(MailboxProperties properties)
+			throws IOException, ApiException {
+		if (!properties.isOwner()) throw new IllegalArgumentException();
+		Request request = getRequestBuilder(properties.getAuthToken())
+				.url(properties.getBaseUrl() + "/setup")
+				.put(EMPTY_REQUEST)
+				.build();
+		OkHttpClient client = httpClientProvider.get();
+		Response response = client.newCall(request).execute();
+		if (response.code() == 401) throw new MailboxAlreadyPairedException();
+		if (!response.isSuccessful()) throw new ApiException();
+		ResponseBody body = response.body();
+		if (body == null) throw new ApiException();
+		try {
+			JsonNode node = mapper.readTree(body.string());
+			JsonNode tokenNode = node.get("token");
+			if (tokenNode == null) {
+				throw new ApiException();
+			}
+			return new MailboxProperties(properties.getBaseUrl(),
+					MailboxAuthToken.fromString(tokenNode.textValue()),
+					parseServerSupports(node));
+		} catch (JacksonException | InvalidMailboxIdException e) {
+			throw new ApiException();
+		}
+	}
+
+	private List<MailboxVersion> parseServerSupports(JsonNode node)
+			throws ApiException {
+		List<MailboxVersion> serverSupports = new ArrayList<>();
+		ArrayNode serverSupportsNode = getArray(node, "serverSupports");
+		for (JsonNode versionNode : serverSupportsNode) {
+			if (!versionNode.isObject()) throw new ApiException();
+			ObjectNode objectNode = (ObjectNode) versionNode;
+			JsonNode majorNode = objectNode.get("major");
+			JsonNode minorNode = objectNode.get("minor");
+			if (majorNode == null || !majorNode.isNumber()) {
+				throw new ApiException();
+			}
+			if (minorNode == null || !minorNode.isNumber()) {
+				throw new ApiException();
+			}
+			int major = majorNode.asInt();
+			int minor = minorNode.asInt();
+			if (major < 0 || minor < 0) throw new ApiException();
+			serverSupports.add(new MailboxVersion(major, minor));
+		}
+		return serverSupports;
+	}
+
+	@Override
+	public boolean checkStatus(MailboxProperties properties)
+			throws IOException, ApiException {
+		Response response = sendGetRequest(properties, "/status");
+		if (response.code() == 401) throw new ApiException();
+		return response.isSuccessful();
+	}
+
+	@Override
+	public void wipeMailbox(MailboxProperties properties)
+			throws IOException, ApiException {
+		if (!properties.isOwner()) throw new IllegalArgumentException();
+		Request request = getRequestBuilder(properties.getAuthToken())
+				.url(properties.getBaseUrl() + "/")
+				.delete()
+				.build();
+		OkHttpClient client = httpClientProvider.get();
+		Response response = client.newCall(request).execute();
+		if (response.code() != 204) throw new ApiException();
+	}
+
+	/* Contact Management API (owner only) */
+
+	@Override
+	public void addContact(MailboxProperties properties, MailboxContact contact)
+			throws IOException, ApiException, TolerableFailureException {
+		if (!properties.isOwner()) throw new IllegalArgumentException();
+		byte[] bodyBytes = mapper.writeValueAsBytes(contact);
+		RequestBody body = RequestBody.create(JSON, bodyBytes);
+		Response response = sendPostRequest(properties, "/contacts", body);
+		if (response.code() == 409) throw new TolerableFailureException();
+		if (!response.isSuccessful()) throw new ApiException();
+	}
+
+	@Override
+	public void deleteContact(MailboxProperties properties, ContactId contactId)
+			throws IOException, ApiException, TolerableFailureException {
+		if (!properties.isOwner()) throw new IllegalArgumentException();
+		String url = properties.getBaseUrl() + "/contacts/" +
+				contactId.getInt();
+		Request request = getRequestBuilder(properties.getAuthToken())
+				.delete()
+				.url(url)
+				.build();
+		OkHttpClient client = httpClientProvider.get();
+		Response response = client.newCall(request).execute();
+		if (response.code() == 404) throw new TolerableFailureException();
+		if (response.code() != 200) throw new ApiException();
+	}
+
+	@Override
+	public Collection<ContactId> getContacts(MailboxProperties properties)
+			throws IOException, ApiException {
+		if (!properties.isOwner()) throw new IllegalArgumentException();
+		Response response = sendGetRequest(properties, "/contacts");
+		if (response.code() != 200) throw new ApiException();
+
+		ResponseBody body = response.body();
+		if (body == null) throw new ApiException();
+		try {
+			JsonNode node = mapper.readTree(body.string());
+			ArrayNode contactsNode = getArray(node, "contacts");
+			List<ContactId> list = new ArrayList<>();
+			for (JsonNode contactNode : contactsNode) {
+				if (!contactNode.isNumber()) throw new ApiException();
+				int id = contactNode.intValue();
+				if (id < 1) throw new ApiException();
+				list.add(new ContactId(id));
+			}
+			return list;
+		} catch (JacksonException e) {
+			throw new ApiException();
+		}
+	}
+
+	/* File Management (owner and contacts) */
+
+	@Override
+	public void addFile(MailboxProperties properties, MailboxFolderId folderId,
+			File file) throws IOException, ApiException {
+		String path = "/files/" + folderId;
+		RequestBody body = RequestBody.create(FILE, file);
+		Response response = sendPostRequest(properties, path, body);
+		if (response.code() != 200) throw new ApiException();
+	}
+
+	@Override
+	public List<MailboxFile> getFiles(MailboxProperties properties,
+			MailboxFolderId folderId) throws IOException, ApiException {
+		String path = "/files/" + folderId;
+		Response response = sendGetRequest(properties, path);
+		if (response.code() != 200) throw new ApiException();
+
+		ResponseBody body = response.body();
+		if (body == null) throw new ApiException();
+		try {
+			JsonNode node = mapper.readTree(body.string());
+			ArrayNode filesNode = getArray(node, "files");
+			List<MailboxFile> list = new ArrayList<>();
+			for (JsonNode fileNode : filesNode) {
+				if (!fileNode.isObject()) throw new ApiException();
+				ObjectNode objectNode = (ObjectNode) fileNode;
+				JsonNode nameNode = objectNode.get("name");
+				JsonNode timeNode = objectNode.get("time");
+				if (nameNode == null || !nameNode.isTextual()) {
+					throw new ApiException();
+				}
+				if (timeNode == null || !timeNode.isNumber()) {
+					throw new ApiException();
+				}
+				String name = nameNode.asText();
+				long time = timeNode.asLong();
+				if (time < 1) throw new ApiException();
+				list.add(new MailboxFile(MailboxFileId.fromString(name), time));
+			}
+			Collections.sort(list);
+			return list;
+		} catch (JacksonException | InvalidMailboxIdException e) {
+			throw new ApiException();
+		}
+	}
+
+	@Override
+	public void getFile(MailboxProperties properties, MailboxFolderId folderId,
+			MailboxFileId fileId, File file) throws IOException, ApiException {
+		String path = "/files/" + folderId + "/" + fileId;
+		Response response = sendGetRequest(properties, path);
+		if (response.code() != 200) throw new ApiException();
+
+		ResponseBody body = response.body();
+		if (body == null) throw new ApiException();
+		FileOutputStream outputStream = new FileOutputStream(file);
+		copyAndClose(body.byteStream(), outputStream);
+	}
+
+	@Override
+	public void deleteFile(MailboxProperties properties,
+			MailboxFolderId folderId, MailboxFileId fileId)
+			throws IOException, ApiException, TolerableFailureException {
+		String path = "/files/" + folderId + "/" + fileId;
+		Request request = getRequestBuilder(properties.getAuthToken())
+				.delete()
+				.url(properties.getBaseUrl() + path)
+				.build();
+		OkHttpClient client = httpClientProvider.get();
+		Response response = client.newCall(request).execute();
+		if (response.code() == 404) throw new TolerableFailureException();
+		if (response.code() != 200) throw new ApiException();
+	}
+
+	@Override
+	public List<MailboxFolderId> getFolders(MailboxProperties properties)
+			throws IOException, ApiException {
+		if (!properties.isOwner()) throw new IllegalArgumentException();
+		Response response = sendGetRequest(properties, "/folders");
+		if (response.code() != 200) throw new ApiException();
+
+		ResponseBody body = response.body();
+		if (body == null) throw new ApiException();
+		try {
+			JsonNode node = mapper.readTree(body.string());
+			ArrayNode filesNode = getArray(node, "folders");
+			List<MailboxFolderId> list = new ArrayList<>();
+			for (JsonNode fileNode : filesNode) {
+				if (!fileNode.isObject()) throw new ApiException();
+				ObjectNode objectNode = (ObjectNode) fileNode;
+				JsonNode idNode = objectNode.get("id");
+				if (idNode == null || !idNode.isTextual()) {
+					throw new ApiException();
+				}
+				String id = idNode.asText();
+				list.add(MailboxFolderId.fromString(id));
+			}
+			return list;
+		} catch (JacksonException | InvalidMailboxIdException e) {
+			throw new ApiException();
+		}
+	}
+
+	/* Helper Functions */
+
+	private Response sendGetRequest(MailboxProperties properties, String path)
+			throws IOException {
+		Request request = getRequestBuilder(properties.getAuthToken())
+				.url(properties.getBaseUrl() + path)
+				.build();
+		OkHttpClient client = httpClientProvider.get();
+		return client.newCall(request).execute();
+	}
+
+	private Response sendPostRequest(MailboxProperties properties, String path,
+			RequestBody body) throws IOException {
+		Request request = getRequestBuilder(properties.getAuthToken())
+				.url(properties.getBaseUrl() + path)
+				.post(body)
+				.build();
+		OkHttpClient client = httpClientProvider.get();
+		return client.newCall(request).execute();
+	}
+
+	private Request.Builder getRequestBuilder(MailboxId token) {
+		return new Request.Builder()
+				.addHeader("Authorization", "Bearer " + token);
+	}
+
+	/* JSON helpers */
+
+	private ArrayNode getArray(JsonNode node, String name) throws ApiException {
+		JsonNode arrayNode = node.get(name);
+		if (arrayNode == null || !arrayNode.isArray()) {
+			throw new ApiException();
+		}
+		return (ArrayNode) arrayNode;
+	}
+
+}

bramble-core/src/main/java/org/briarproject/bramble/mailbox/MailboxManagerImpl.java

@@ -0,0 +1,156 @@
+package org.briarproject.bramble.mailbox;
+
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.db.Transaction;
+import org.briarproject.bramble.api.db.TransactionManager;
+import org.briarproject.bramble.api.lifecycle.IoExecutor;
+import org.briarproject.bramble.api.mailbox.MailboxManager;
+import org.briarproject.bramble.api.mailbox.MailboxPairingTask;
+import org.briarproject.bramble.api.mailbox.MailboxProperties;
+import org.briarproject.bramble.api.mailbox.MailboxSettingsManager;
+import org.briarproject.bramble.api.mailbox.MailboxStatus;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.system.Clock;
+
+import java.io.IOException;
+import java.util.concurrent.Executor;
+import java.util.logging.Logger;
+
+import javax.annotation.Nullable;
+import javax.annotation.concurrent.GuardedBy;
+import javax.annotation.concurrent.Immutable;
+import javax.inject.Inject;
+
+import static java.util.logging.Level.WARNING;
+import static java.util.logging.Logger.getLogger;
+import static org.briarproject.bramble.util.LogUtils.logException;
+
+@Immutable
+@NotNullByDefault
+class MailboxManagerImpl implements MailboxManager {
+
+	private static final String TAG = MailboxManagerImpl.class.getName();
+	private final static Logger LOG = getLogger(TAG);
+
+	private final Executor ioExecutor;
+	private final MailboxApi api;
+	private final TransactionManager db;
+	private final MailboxSettingsManager mailboxSettingsManager;
+	private final MailboxPairingTaskFactory pairingTaskFactory;
+	private final Clock clock;
+	private final Object lock = new Object();
+
+	@Nullable
+	@GuardedBy("lock")
+	private MailboxPairingTask pairingTask = null;
+
+	@Inject
+	MailboxManagerImpl(
+			@IoExecutor Executor ioExecutor,
+			MailboxApi api,
+			TransactionManager db,
+			MailboxSettingsManager mailboxSettingsManager,
+			MailboxPairingTaskFactory pairingTaskFactory,
+			Clock clock) {
+		this.ioExecutor = ioExecutor;
+		this.api = api;
+		this.db = db;
+		this.mailboxSettingsManager = mailboxSettingsManager;
+		this.pairingTaskFactory = pairingTaskFactory;
+		this.clock = clock;
+	}
+
+	@Override
+	public boolean isPaired(Transaction txn) throws DbException {
+		return mailboxSettingsManager.getOwnMailboxProperties(txn) != null;
+	}
+
+	@Override
+	public MailboxStatus getMailboxStatus(Transaction txn) throws DbException {
+		return mailboxSettingsManager.getOwnMailboxStatus(txn);
+	}
+
+	@Nullable
+	@Override
+	public MailboxPairingTask getCurrentPairingTask() {
+		synchronized (lock) {
+			return pairingTask;
+		}
+	}
+
+	@Override
+	public MailboxPairingTask startPairingTask(String payload) {
+		MailboxPairingTask created;
+		synchronized (lock) {
+			if (pairingTask != null) return pairingTask;
+			created = pairingTaskFactory.createPairingTask(payload);
+			pairingTask = created;
+		}
+		ioExecutor.execute(() -> {
+			created.run();
+			synchronized (lock) {
+				// remove task after it finished
+				pairingTask = null;
+			}
+		});
+		return created;
+	}
+
+	@Override
+	public boolean checkConnection() {
+		boolean success;
+		try {
+			MailboxProperties props = db.transactionWithNullableResult(true,
+					mailboxSettingsManager::getOwnMailboxProperties);
+			if (props == null) throw new DbException();
+			success = api.checkStatus(props);
+		} catch (DbException e) {
+			logException(LOG, WARNING, e);
+			// we don't treat this is a failure to record
+			return false;
+		} catch (IOException | MailboxApi.ApiException e) {
+			// we record this as a failure
+			success = false;
+			logException(LOG, WARNING, e);
+		}
+		try {
+			recordCheckResult(success);
+		} catch (DbException e) {
+			logException(LOG, WARNING, e);
+		}
+		return success;
+	}
+
+	private void recordCheckResult(boolean success) throws DbException {
+		long now = clock.currentTimeMillis();
+		db.transaction(false, txn -> {
+			if (success) {
+				mailboxSettingsManager.recordSuccessfulConnection(txn, now);
+			} else {
+				mailboxSettingsManager.recordFailedConnectionAttempt(txn, now);
+			}
+		});
+	}
+
+	@Override
+	public boolean unPair() throws DbException {
+		MailboxProperties properties = db.transactionWithNullableResult(true,
+				mailboxSettingsManager::getOwnMailboxProperties);
+		if (properties == null) {
+			// no more mailbox, that's strange but possible if called in quick
+			// succession, so let's return true this time
+			return true;
+		}
+		boolean wasWiped;
+		try {
+			api.wipeMailbox(properties);
+			wasWiped = true;
+		} catch (IOException | MailboxApi.ApiException e) {
+			logException(LOG, WARNING, e);
+			wasWiped = false;
+		}
+		db.transaction(false,
+				mailboxSettingsManager::removeOwnMailboxProperties);
+		return wasWiped;
+	}
+}

bramble-core/src/main/java/org/briarproject/bramble/mailbox/MailboxModule.java

@@ -0,0 +1,104 @@
+package org.briarproject.bramble.mailbox;
+
+import org.briarproject.bramble.api.FeatureFlags;
+import org.briarproject.bramble.api.client.ClientHelper;
+import org.briarproject.bramble.api.contact.ContactManager;
+import org.briarproject.bramble.api.data.MetadataEncoder;
+import org.briarproject.bramble.api.lifecycle.LifecycleManager;
+import org.briarproject.bramble.api.mailbox.MailboxManager;
+import org.briarproject.bramble.api.mailbox.MailboxSettingsManager;
+import org.briarproject.bramble.api.mailbox.MailboxUpdateManager;
+import org.briarproject.bramble.api.mailbox.MailboxVersion;
+import org.briarproject.bramble.api.sync.validation.ValidationManager;
+import org.briarproject.bramble.api.system.Clock;
+import org.briarproject.bramble.api.versioning.ClientVersioningManager;
+
+import java.util.List;
+
+import javax.inject.Inject;
+import javax.inject.Singleton;
+
+import dagger.Module;
+import dagger.Provides;
+
+import static org.briarproject.bramble.api.mailbox.MailboxUpdateManager.CLIENT_ID;
+import static org.briarproject.bramble.api.mailbox.MailboxUpdateManager.MAJOR_VERSION;
+import static org.briarproject.bramble.api.mailbox.MailboxUpdateManager.MINOR_VERSION;
+import static org.briarproject.bramble.mailbox.MailboxApi.CLIENT_SUPPORTS;
+
+@Module
+public class MailboxModule {
+
+	public static class EagerSingletons {
+		@Inject
+		MailboxUpdateValidator mailboxUpdateValidator;
+		@Inject
+		MailboxUpdateManager mailboxUpdateManager;
+	}
+
+	@Provides
+	@Singleton
+	MailboxManager providesMailboxManager(MailboxManagerImpl mailboxManager) {
+		return mailboxManager;
+	}
+
+	@Provides
+	MailboxPairingTaskFactory provideMailboxPairingTaskFactory(
+			MailboxPairingTaskFactoryImpl mailboxPairingTaskFactory) {
+		return mailboxPairingTaskFactory;
+	}
+
+	@Provides
+	MailboxSettingsManager provideMailboxSettingsManager(
+			MailboxSettingsManagerImpl mailboxSettingsManager) {
+		return mailboxSettingsManager;
+	}
+
+	@Provides
+	MailboxApi providesMailboxApi(MailboxApiImpl mailboxApi) {
+		return mailboxApi;
+	}
+
+	@Provides
+	@Singleton
+	MailboxUpdateValidator provideMailboxUpdateValidator(
+			ValidationManager validationManager,
+			ClientHelper clientHelper,
+			MetadataEncoder metadataEncoder,
+			Clock clock,
+			FeatureFlags featureFlags) {
+		MailboxUpdateValidator validator = new MailboxUpdateValidator(
+				clientHelper, metadataEncoder, clock);
+		if (featureFlags.shouldEnableMailbox()) {
+			validationManager.registerMessageValidator(CLIENT_ID,
+					MAJOR_VERSION, validator);
+		}
+		return validator;
+	}
+
+	@Provides
+	List<MailboxVersion> provideClientSupports() {
+		return CLIENT_SUPPORTS;
+	}
+
+	@Provides
+	@Singleton
+	MailboxUpdateManager provideMailboxUpdateManager(
+			FeatureFlags featureFlags,
+			LifecycleManager lifecycleManager,
+			ValidationManager validationManager, ContactManager contactManager,
+			ClientVersioningManager clientVersioningManager,
+			MailboxSettingsManager mailboxSettingsManager,
+			MailboxUpdateManagerImpl mailboxUpdateManager) {
+		if (featureFlags.shouldEnableMailbox()) {
+			lifecycleManager.registerOpenDatabaseHook(mailboxUpdateManager);
+			validationManager.registerIncomingMessageHook(CLIENT_ID,
+					MAJOR_VERSION, mailboxUpdateManager);
+			contactManager.registerContactHook(mailboxUpdateManager);
+			clientVersioningManager.registerClient(CLIENT_ID, MAJOR_VERSION,
+					MINOR_VERSION, mailboxUpdateManager);
+			mailboxSettingsManager.registerMailboxHook(mailboxUpdateManager);
+		}
+		return mailboxUpdateManager;
+	}
+}

bramble-core/src/main/java/org/briarproject/bramble/mailbox/MailboxPairingTaskFactory.java

@@ -0,0 +1,12 @@
+package org.briarproject.bramble.mailbox;
+
+
+import org.briarproject.bramble.api.mailbox.MailboxPairingTask;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+@NotNullByDefault
+interface MailboxPairingTaskFactory {
+
+	MailboxPairingTask createPairingTask(String qrCodePayload);
+
+}

bramble-core/src/main/java/org/briarproject/bramble/mailbox/MailboxPairingTaskFactoryImpl.java

@@ -0,0 +1,53 @@
+package org.briarproject.bramble.mailbox;
+
+import org.briarproject.bramble.api.crypto.CryptoComponent;
+import org.briarproject.bramble.api.db.DatabaseComponent;
+import org.briarproject.bramble.api.event.EventExecutor;
+import org.briarproject.bramble.api.mailbox.MailboxPairingTask;
+import org.briarproject.bramble.api.mailbox.MailboxSettingsManager;
+import org.briarproject.bramble.api.mailbox.MailboxUpdateManager;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.system.Clock;
+
+import java.util.concurrent.Executor;
+
+import javax.annotation.concurrent.Immutable;
+import javax.inject.Inject;
+
+@Immutable
+@NotNullByDefault
+class MailboxPairingTaskFactoryImpl implements MailboxPairingTaskFactory {
+
+	private final Executor eventExecutor;
+	private final DatabaseComponent db;
+	private final CryptoComponent crypto;
+	private final Clock clock;
+	private final MailboxApi api;
+	private final MailboxSettingsManager mailboxSettingsManager;
+	private final MailboxUpdateManager mailboxUpdateManager;
+
+	@Inject
+	MailboxPairingTaskFactoryImpl(
+			@EventExecutor Executor eventExecutor,
+			DatabaseComponent db,
+			CryptoComponent crypto,
+			Clock clock,
+			MailboxApi api,
+			MailboxSettingsManager mailboxSettingsManager,
+			MailboxUpdateManager mailboxUpdateManager) {
+		this.eventExecutor = eventExecutor;
+		this.db = db;
+		this.crypto = crypto;
+		this.clock = clock;
+		this.api = api;
+		this.mailboxSettingsManager = mailboxSettingsManager;
+		this.mailboxUpdateManager = mailboxUpdateManager;
+	}
+
+	@Override
+	public MailboxPairingTask createPairingTask(String qrCodePayload) {
+		return new MailboxPairingTaskImpl(qrCodePayload, eventExecutor, db,
+				crypto, clock, api, mailboxSettingsManager,
+				mailboxUpdateManager);
+	}
+}

bramble-core/src/main/java/org/briarproject/bramble/mailbox/MailboxPairingTaskImpl.java

@@ -0,0 +1,186 @@
+package org.briarproject.bramble.mailbox;
+
+import org.briarproject.bramble.api.Consumer;
+import org.briarproject.bramble.api.FormatException;
+import org.briarproject.bramble.api.contact.Contact;
+import org.briarproject.bramble.api.crypto.CryptoComponent;
+import org.briarproject.bramble.api.db.DatabaseComponent;
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.event.EventExecutor;
+import org.briarproject.bramble.api.mailbox.MailboxAuthToken;
+import org.briarproject.bramble.api.mailbox.MailboxPairingState;
+import org.briarproject.bramble.api.mailbox.MailboxPairingTask;
+import org.briarproject.bramble.api.mailbox.MailboxProperties;
+import org.briarproject.bramble.api.mailbox.MailboxSettingsManager;
+import org.briarproject.bramble.api.mailbox.MailboxUpdate;
+import org.briarproject.bramble.api.mailbox.MailboxUpdateManager;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.system.Clock;
+import org.briarproject.bramble.mailbox.MailboxApi.ApiException;
+import org.briarproject.bramble.mailbox.MailboxApi.MailboxAlreadyPairedException;
+
+import java.io.IOException;
+import java.nio.charset.Charset;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+import java.util.concurrent.Executor;
+import java.util.logging.Logger;
+
+import javax.annotation.concurrent.GuardedBy;
+import javax.annotation.concurrent.ThreadSafe;
+
+import static java.util.logging.Level.WARNING;
+import static java.util.logging.Logger.getLogger;
+import static org.briarproject.bramble.util.LogUtils.logException;
+
+@ThreadSafe
+@NotNullByDefault
+class MailboxPairingTaskImpl implements MailboxPairingTask {
+
+	private final static Logger LOG =
+			getLogger(MailboxPairingTaskImpl.class.getName());
+	@SuppressWarnings("CharsetObjectCanBeUsed") // Requires minSdkVersion >= 19
+	private static final Charset ISO_8859_1 = Charset.forName("ISO-8859-1");
+	private static final int VERSION_REQUIRED = 32;
+
+	private final String payload;
+	private final Executor eventExecutor;
+	private final DatabaseComponent db;
+	private final CryptoComponent crypto;
+	private final Clock clock;
+	private final MailboxApi api;
+	private final MailboxSettingsManager mailboxSettingsManager;
+	private final MailboxUpdateManager mailboxUpdateManager;
+
+	private final Object lock = new Object();
+	@GuardedBy("lock")
+	private final List<Consumer<MailboxPairingState>> observers =
+			new ArrayList<>();
+	@GuardedBy("lock")
+	private MailboxPairingState state;
+
+	MailboxPairingTaskImpl(
+			String payload,
+			@EventExecutor Executor eventExecutor,
+			DatabaseComponent db,
+			CryptoComponent crypto,
+			Clock clock,
+			MailboxApi api,
+			MailboxSettingsManager mailboxSettingsManager,
+			MailboxUpdateManager mailboxUpdateManager) {
+		this.payload = payload;
+		this.eventExecutor = eventExecutor;
+		this.db = db;
+		this.crypto = crypto;
+		this.clock = clock;
+		this.api = api;
+		this.mailboxSettingsManager = mailboxSettingsManager;
+		this.mailboxUpdateManager = mailboxUpdateManager;
+		state = new MailboxPairingState.QrCodeReceived();
+	}
+
+	@Override
+	public void addObserver(Consumer<MailboxPairingState> o) {
+		MailboxPairingState state;
+		synchronized (lock) {
+			observers.add(o);
+			state = this.state;
+			eventExecutor.execute(() -> o.accept(state));
+		}
+	}
+
+	@Override
+	public void removeObserver(Consumer<MailboxPairingState> o) {
+		synchronized (lock) {
+			observers.remove(o);
+		}
+	}
+
+	@Override
+	public void run() {
+		try {
+			pairMailbox();
+		} catch (FormatException e) {
+			onMailboxError(e, new MailboxPairingState.InvalidQrCode());
+		} catch (MailboxAlreadyPairedException e) {
+			onMailboxError(e, new MailboxPairingState.MailboxAlreadyPaired());
+		} catch (IOException e) {
+			onMailboxError(e, new MailboxPairingState.ConnectionError());
+		} catch (ApiException | DbException e) {
+			onMailboxError(e, new MailboxPairingState.UnexpectedError());
+		}
+	}
+
+	private void pairMailbox() throws IOException, ApiException, DbException {
+		MailboxProperties mailboxProperties = decodeQrCodePayload(payload);
+		setState(new MailboxPairingState.Pairing());
+		MailboxProperties ownerProperties = api.setup(mailboxProperties);
+		long time = clock.currentTimeMillis();
+		db.transaction(false, txn -> {
+			mailboxSettingsManager
+					.setOwnMailboxProperties(txn, ownerProperties);
+			mailboxSettingsManager.recordSuccessfulConnection(txn, time);
+			// A (possibly new) mailbox is paired. Reset message retransmission
+			// timers for contacts who doesn't have their own mailbox. This way,
+			// data stranded on our old mailbox will be re-uploaded to our new.
+			for (Contact c : db.getContacts(txn)) {
+				MailboxUpdate update = mailboxUpdateManager.getRemoteUpdate(
+						txn, c.getId());
+				if (update == null || !update.hasMailbox()) {
+					db.resetUnackedMessagesToSend(txn, c.getId());
+				}
+			}
+		});
+		setState(new MailboxPairingState.Paired());
+	}
+
+	private void onMailboxError(Exception e, MailboxPairingState state) {
+		logException(LOG, WARNING, e);
+		setState(state);
+	}
+
+	private void setState(MailboxPairingState state) {
+		synchronized (lock) {
+			this.state = state;
+			notifyObservers();
+		}
+	}
+
+	@GuardedBy("lock")
+	private void notifyObservers() {
+		List<Consumer<MailboxPairingState>> observers =
+				new ArrayList<>(this.observers);
+		MailboxPairingState state = this.state;
+		eventExecutor.execute(() -> {
+			for (Consumer<MailboxPairingState> o : observers) o.accept(state);
+		});
+	}
+
+	private MailboxProperties decodeQrCodePayload(String payload)
+			throws FormatException {
+		byte[] bytes = payload.getBytes(ISO_8859_1);
+		if (bytes.length != 65) {
+			if (LOG.isLoggable(WARNING)) {
+				LOG.warning("QR code length is not 65: " + bytes.length);
+			}
+			throw new FormatException();
+		}
+		int version = bytes[0] & 0xFF;
+		if (version != VERSION_REQUIRED) {
+			if (LOG.isLoggable(WARNING)) {
+				LOG.warning("QR code has not version " + VERSION_REQUIRED +
+						": " + version);
+			}
+			throw new FormatException();
+		}
+		LOG.info("QR code is valid");
+		byte[] onionPubKey = Arrays.copyOfRange(bytes, 1, 33);
+		String onion = crypto.encodeOnion(onionPubKey);
+		String baseUrl = "http://" + onion + ".onion"; // TODO
+		byte[] tokenBytes = Arrays.copyOfRange(bytes, 33, 65);
+		MailboxAuthToken setupToken = new MailboxAuthToken(tokenBytes);
+		return new MailboxProperties(baseUrl, setupToken, new ArrayList<>());
+	}
+
+}

bramble-core/src/main/java/org/briarproject/bramble/mailbox/MailboxSettingsManagerImpl.java

@@ -0,0 +1,168 @@
+package org.briarproject.bramble.mailbox;
+
+import org.briarproject.bramble.api.contact.ContactId;
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.db.Transaction;
+import org.briarproject.bramble.api.mailbox.InvalidMailboxIdException;
+import org.briarproject.bramble.api.mailbox.MailboxAuthToken;
+import org.briarproject.bramble.api.mailbox.MailboxProperties;
+import org.briarproject.bramble.api.mailbox.MailboxSettingsManager;
+import org.briarproject.bramble.api.mailbox.MailboxStatus;
+import org.briarproject.bramble.api.mailbox.MailboxVersion;
+import org.briarproject.bramble.api.mailbox.event.MailboxProblemEvent;
+import org.briarproject.bramble.api.mailbox.event.OwnMailboxConnectionStatusEvent;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.settings.Settings;
+import org.briarproject.bramble.api.settings.SettingsManager;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.CopyOnWriteArrayList;
+
+import javax.annotation.Nullable;
+import javax.annotation.concurrent.Immutable;
+import javax.inject.Inject;
+
+import static org.briarproject.bramble.util.StringUtils.isNullOrEmpty;
+
+@Immutable
+@NotNullByDefault
+class MailboxSettingsManagerImpl implements MailboxSettingsManager {
+
+	// Package access for testing
+	static final String SETTINGS_NAMESPACE = "mailbox";
+	// TODO: This currently stores the base URL, not the 56-char onion address
+	static final String SETTINGS_KEY_ONION = "onion";
+	static final String SETTINGS_KEY_TOKEN = "token";
+	static final String SETTINGS_KEY_SERVER_SUPPORTS = "serverSupports";
+	static final String SETTINGS_KEY_LAST_ATTEMPT = "lastAttempt";
+	static final String SETTINGS_KEY_LAST_SUCCESS = "lastSuccess";
+	static final String SETTINGS_KEY_ATTEMPTS = "attempts";
+	static final String SETTINGS_UPLOADS_NAMESPACE = "mailbox-uploads";
+
+	private final SettingsManager settingsManager;
+	private final List<MailboxHook> hooks = new CopyOnWriteArrayList<>();
+
+	@Inject
+	MailboxSettingsManagerImpl(SettingsManager settingsManager) {
+		this.settingsManager = settingsManager;
+	}
+
+	@Override
+	public void registerMailboxHook(MailboxHook hook) {
+		hooks.add(hook);
+	}
+
+	@Override
+	public MailboxProperties getOwnMailboxProperties(Transaction txn)
+			throws DbException {
+		Settings s = settingsManager.getSettings(txn, SETTINGS_NAMESPACE);
+		String onion = s.get(SETTINGS_KEY_ONION);
+		String token = s.get(SETTINGS_KEY_TOKEN);
+		if (isNullOrEmpty(onion) || isNullOrEmpty(token)) return null;
+		int[] ints = s.getIntArray(SETTINGS_KEY_SERVER_SUPPORTS);
+		// We know we were paired, so we must have proper serverSupports
+		if (ints == null || ints.length == 0 || ints.length % 2 != 0) {
+			throw new DbException();
+		}
+		List<MailboxVersion> serverSupports = new ArrayList<>();
+		for (int i = 0; i < ints.length - 1; i += 2) {
+			serverSupports.add(new MailboxVersion(ints[i], ints[i + 1]));
+		}
+		try {
+			MailboxAuthToken tokenId = MailboxAuthToken.fromString(token);
+			return new MailboxProperties(onion, tokenId, serverSupports);
+		} catch (InvalidMailboxIdException e) {
+			throw new DbException(e);
+		}
+	}
+
+	@Override
+	public void setOwnMailboxProperties(Transaction txn, MailboxProperties p)
+			throws DbException {
+		Settings s = new Settings();
+		s.put(SETTINGS_KEY_ONION, p.getBaseUrl());
+		s.put(SETTINGS_KEY_TOKEN, p.getAuthToken().toString());
+		List<MailboxVersion> serverSupports = p.getServerSupports();
+		int[] ints = new int[serverSupports.size() * 2];
+		int i = 0;
+		for (MailboxVersion v : serverSupports) {
+			ints[i++] = v.getMajor();
+			ints[i++] = v.getMinor();
+		}
+		s.putIntArray(SETTINGS_KEY_SERVER_SUPPORTS, ints);
+		settingsManager.mergeSettings(txn, s, SETTINGS_NAMESPACE);
+		for (MailboxHook hook : hooks) {
+			hook.mailboxPaired(txn, p.getOnion(), p.getServerSupports());
+		}
+	}
+
+	@Override
+	public void removeOwnMailboxProperties(Transaction txn) throws DbException {
+		Settings s = new Settings();
+		s.put(SETTINGS_KEY_ONION, "");
+		s.put(SETTINGS_KEY_TOKEN, "");
+		settingsManager.mergeSettings(txn, s, SETTINGS_NAMESPACE);
+		for (MailboxHook hook : hooks) {
+			hook.mailboxUnpaired(txn);
+		}
+	}
+
+	@Override
+	public MailboxStatus getOwnMailboxStatus(Transaction txn)
+			throws DbException {
+		Settings s = settingsManager.getSettings(txn, SETTINGS_NAMESPACE);
+		long lastAttempt = s.getLong(SETTINGS_KEY_LAST_ATTEMPT, -1);
+		long lastSuccess = s.getLong(SETTINGS_KEY_LAST_SUCCESS, -1);
+		int attempts = s.getInt(SETTINGS_KEY_ATTEMPTS, 0);
+		return new MailboxStatus(lastAttempt, lastSuccess, attempts);
+	}
+
+	@Override
+	public void recordSuccessfulConnection(Transaction txn, long now)
+			throws DbException {
+		Settings s = new Settings();
+		s.putLong(SETTINGS_KEY_LAST_ATTEMPT, now);
+		s.putLong(SETTINGS_KEY_LAST_SUCCESS, now);
+		s.putInt(SETTINGS_KEY_ATTEMPTS, 0);
+		settingsManager.mergeSettings(txn, s, SETTINGS_NAMESPACE);
+		MailboxStatus status = new MailboxStatus(now, now, 0);
+		txn.attach(new OwnMailboxConnectionStatusEvent(status));
+	}
+
+	@Override
+	public void recordFailedConnectionAttempt(Transaction txn, long now)
+			throws DbException {
+		Settings oldSettings =
+				settingsManager.getSettings(txn, SETTINGS_NAMESPACE);
+		int newAttempts = 1 + oldSettings.getInt(SETTINGS_KEY_ATTEMPTS, 0);
+		long lastSuccess = oldSettings.getLong(SETTINGS_KEY_LAST_SUCCESS, 0);
+		Settings newSettings = new Settings();
+		newSettings.putLong(SETTINGS_KEY_LAST_ATTEMPT, now);
+		newSettings.putInt(SETTINGS_KEY_ATTEMPTS, newAttempts);
+		settingsManager.mergeSettings(txn, newSettings, SETTINGS_NAMESPACE);
+		MailboxStatus status = new MailboxStatus(now, lastSuccess, newAttempts);
+		txn.attach(new OwnMailboxConnectionStatusEvent(status));
+		if (status.hasProblem(now)) txn.attach(new MailboxProblemEvent());
+	}
+
+	@Override
+	public void setPendingUpload(Transaction txn, ContactId id,
+			@Nullable String filename) throws DbException {
+		Settings s = new Settings();
+		String value = filename == null ? "" : filename;
+		s.put(String.valueOf(id.getInt()), value);
+		settingsManager.mergeSettings(txn, s, SETTINGS_UPLOADS_NAMESPACE);
+	}
+
+	@Nullable
+	@Override
+	public String getPendingUpload(Transaction txn, ContactId id)
+			throws DbException {
+		Settings s =
+				settingsManager.getSettings(txn, SETTINGS_UPLOADS_NAMESPACE);
+		String filename = s.get(String.valueOf(id.getInt()));
+		if (isNullOrEmpty(filename)) return null;
+		return filename;
+	}
+}

bramble-core/src/main/java/org/briarproject/bramble/mailbox/MailboxUpdateManagerImpl.java

@@ -0,0 +1,373 @@
+package org.briarproject.bramble.mailbox;
+
+import org.briarproject.bramble.api.FormatException;
+import org.briarproject.bramble.api.client.ClientHelper;
+import org.briarproject.bramble.api.client.ContactGroupFactory;
+import org.briarproject.bramble.api.contact.Contact;
+import org.briarproject.bramble.api.contact.ContactId;
+import org.briarproject.bramble.api.contact.ContactManager.ContactHook;
+import org.briarproject.bramble.api.crypto.CryptoComponent;
+import org.briarproject.bramble.api.data.BdfDictionary;
+import org.briarproject.bramble.api.data.BdfEntry;
+import org.briarproject.bramble.api.data.BdfList;
+import org.briarproject.bramble.api.data.MetadataParser;
+import org.briarproject.bramble.api.db.DatabaseComponent;
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.db.Metadata;
+import org.briarproject.bramble.api.db.Transaction;
+import org.briarproject.bramble.api.lifecycle.LifecycleManager.OpenDatabaseHook;
+import org.briarproject.bramble.api.mailbox.MailboxAuthToken;
+import org.briarproject.bramble.api.mailbox.MailboxFolderId;
+import org.briarproject.bramble.api.mailbox.MailboxProperties;
+import org.briarproject.bramble.api.mailbox.MailboxSettingsManager;
+import org.briarproject.bramble.api.mailbox.MailboxSettingsManager.MailboxHook;
+import org.briarproject.bramble.api.mailbox.MailboxUpdate;
+import org.briarproject.bramble.api.mailbox.MailboxUpdateManager;
+import org.briarproject.bramble.api.mailbox.MailboxUpdateWithMailbox;
+import org.briarproject.bramble.api.mailbox.MailboxVersion;
+import org.briarproject.bramble.api.mailbox.event.RemoteMailboxUpdateEvent;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.sync.Group;
+import org.briarproject.bramble.api.sync.Group.Visibility;
+import org.briarproject.bramble.api.sync.GroupId;
+import org.briarproject.bramble.api.sync.InvalidMessageException;
+import org.briarproject.bramble.api.sync.Message;
+import org.briarproject.bramble.api.sync.MessageId;
+import org.briarproject.bramble.api.sync.validation.IncomingMessageHook;
+import org.briarproject.bramble.api.system.Clock;
+import org.briarproject.bramble.api.versioning.ClientVersioningManager;
+import org.briarproject.bramble.api.versioning.ClientVersioningManager.ClientVersioningHook;
+
+import java.util.List;
+import java.util.Map;
+import java.util.Map.Entry;
+
+import javax.annotation.Nullable;
+import javax.inject.Inject;
+
+import static org.briarproject.bramble.api.sync.validation.IncomingMessageHook.DeliveryAction.ACCEPT_DO_NOT_SHARE;
+
+@NotNullByDefault
+class MailboxUpdateManagerImpl implements MailboxUpdateManager,
+		OpenDatabaseHook, ContactHook, ClientVersioningHook,
+		IncomingMessageHook, MailboxHook {
+
+	private final List<MailboxVersion> clientSupports;
+	private final DatabaseComponent db;
+	private final ClientHelper clientHelper;
+	private final ClientVersioningManager clientVersioningManager;
+	private final MetadataParser metadataParser;
+	private final ContactGroupFactory contactGroupFactory;
+	private final Clock clock;
+	private final MailboxSettingsManager mailboxSettingsManager;
+	private final CryptoComponent crypto;
+	private final Group localGroup;
+
+	@Inject
+	MailboxUpdateManagerImpl(List<MailboxVersion> clientSupports,
+			DatabaseComponent db, ClientHelper clientHelper,
+			ClientVersioningManager clientVersioningManager,
+			MetadataParser metadataParser,
+			ContactGroupFactory contactGroupFactory, Clock clock,
+			MailboxSettingsManager mailboxSettingsManager,
+			CryptoComponent crypto) {
+		this.clientSupports = clientSupports;
+		this.db = db;
+		this.clientHelper = clientHelper;
+		this.clientVersioningManager = clientVersioningManager;
+		this.metadataParser = metadataParser;
+		this.contactGroupFactory = contactGroupFactory;
+		this.clock = clock;
+		this.mailboxSettingsManager = mailboxSettingsManager;
+		this.crypto = crypto;
+		localGroup = contactGroupFactory.createLocalGroup(CLIENT_ID,
+				MAJOR_VERSION);
+	}
+
+	@Override
+	public void onDatabaseOpened(Transaction txn) throws DbException {
+		if (db.containsGroup(txn, localGroup.getId())) {
+			try {
+				BdfDictionary meta = clientHelper.getGroupMetadataAsDictionary(
+						txn, localGroup.getId());
+				BdfList sent = meta.getList(GROUP_KEY_SENT_CLIENT_SUPPORTS);
+				if (clientHelper.parseMailboxVersionList(sent)
+						.equals(clientSupports)) {
+					return;
+				}
+			} catch (FormatException e) {
+				throw new DbException();
+			}
+			// Our current clientSupports list has changed compared to what we
+			// last sent out.
+			for (Contact c : db.getContacts(txn)) {
+				MailboxUpdate latest = getLocalUpdate(txn, c.getId());
+				MailboxUpdate updated;
+				if (latest.hasMailbox()) {
+					updated = new MailboxUpdateWithMailbox(
+							(MailboxUpdateWithMailbox) latest, clientSupports);
+				} else {
+					updated = new MailboxUpdate(clientSupports);
+				}
+				Group g = getContactGroup(c);
+				storeMessageReplaceLatest(txn, g.getId(), updated);
+			}
+		} else {
+			db.addGroup(txn, localGroup);
+			// Set things up for any pre-existing contacts
+			for (Contact c : db.getContacts(txn)) {
+				addingContact(txn, c);
+			}
+		}
+
+		try {
+			BdfDictionary meta = BdfDictionary.of(new BdfEntry(
+					GROUP_KEY_SENT_CLIENT_SUPPORTS,
+					encodeSupportsList(clientSupports)));
+			clientHelper.mergeGroupMetadata(txn, localGroup.getId(), meta);
+		} catch (FormatException e) {
+			throw new DbException();
+		}
+	}
+
+	@Override
+	public void addingContact(Transaction txn, Contact c) throws DbException {
+		// Create a group to share with the contact
+		Group g = getContactGroup(c);
+		db.addGroup(txn, g);
+		// Apply the client's visibility to the contact group
+		Visibility client = clientVersioningManager
+				.getClientVisibility(txn, c.getId(), CLIENT_ID, MAJOR_VERSION);
+		db.setGroupVisibility(txn, c.getId(), g.getId(), client);
+		// Attach the contact ID to the group
+		clientHelper.setContactId(txn, g.getId(), c.getId());
+		MailboxProperties ownProps =
+				mailboxSettingsManager.getOwnMailboxProperties(txn);
+		if (ownProps != null) {
+			// We are paired, create and send props to the newly added contact
+			createAndSendUpdateWithMailbox(txn, c, ownProps.getServerSupports(),
+					ownProps.getOnion());
+		} else {
+			// Not paired, but we still want to get our clientSupports sent
+			sendUpdateNoMailbox(txn, c);
+		}
+	}
+
+	@Override
+	public void removingContact(Transaction txn, Contact c) throws DbException {
+		db.removeGroup(txn, getContactGroup(c));
+	}
+
+	@Override
+	public void mailboxPaired(Transaction txn, String ownOnion,
+			List<MailboxVersion> serverSupports) throws DbException {
+		for (Contact c : db.getContacts(txn)) {
+			createAndSendUpdateWithMailbox(txn, c, serverSupports, ownOnion);
+		}
+	}
+
+	@Override
+	public void mailboxUnpaired(Transaction txn) throws DbException {
+		for (Contact c : db.getContacts(txn)) {
+			sendUpdateNoMailbox(txn, c);
+		}
+	}
+
+	@Override
+	public void onClientVisibilityChanging(Transaction txn, Contact c,
+			Visibility v) throws DbException {
+		// Apply the client's visibility to the contact group
+		Group g = getContactGroup(c);
+		db.setGroupVisibility(txn, c.getId(), g.getId(), v);
+	}
+
+	@Override
+	public DeliveryAction incomingMessage(Transaction txn, Message m,
+			Metadata meta) throws DbException, InvalidMessageException {
+		try {
+			BdfDictionary d = metadataParser.parse(meta);
+			// Get latest non-local update in the same group (from same contact)
+			LatestUpdate latest = findLatest(txn, m.getGroupId(), false);
+			if (latest != null) {
+				if (d.getLong(MSG_KEY_VERSION) > latest.version) {
+					db.deleteMessage(txn, latest.messageId);
+					db.deleteMessageMetadata(txn, latest.messageId);
+				} else {
+					// Delete this update, we already have a newer one
+					db.deleteMessage(txn, m.getId());
+					db.deleteMessageMetadata(txn, m.getId());
+					return ACCEPT_DO_NOT_SHARE;
+				}
+			}
+			ContactId c = clientHelper.getContactId(txn, m.getGroupId());
+			BdfList body = clientHelper.getMessageAsList(txn, m.getId());
+			MailboxUpdate u = parseUpdate(body);
+			txn.attach(new RemoteMailboxUpdateEvent(c, u));
+			// Reset message retransmission timers for the contact. Avoiding
+			// messages getting stranded:
+			// - on our mailbox, if they now have a mailbox but didn't before
+			// - on the contact's old mailbox, if they removed their mailbox
+			// - on the contact's old mailbox, if they replaced their mailbox
+			db.resetUnackedMessagesToSend(txn, c);
+		} catch (FormatException e) {
+			throw new InvalidMessageException(e);
+		}
+		return ACCEPT_DO_NOT_SHARE;
+	}
+
+	@Override
+	public MailboxUpdate getLocalUpdate(Transaction txn, ContactId c)
+			throws DbException {
+		MailboxUpdate local = getUpdate(txn, db.getContact(txn, c), true);
+		// An update (with or without mailbox) is created when contact is added
+		if (local == null) {
+			throw new DbException();
+		}
+		return local;
+	}
+
+	@Override
+	@Nullable
+	public MailboxUpdate getRemoteUpdate(Transaction txn, ContactId c)
+			throws DbException {
+		return getUpdate(txn, db.getContact(txn, c), false);
+	}
+
+	/**
+	 * Creates and sends an update message to the given contact. The message
+	 * holds our own mailbox's onion, generated unique properties, and lists of
+	 * supported Mailbox API version(s). All of which the contact needs to
+	 * communicate with our Mailbox.
+	 */
+	private void createAndSendUpdateWithMailbox(Transaction txn, Contact c,
+			List<MailboxVersion> serverSupports, String ownOnion)
+			throws DbException {
+		String baseUrl = "http://" + ownOnion + ".onion"; // TODO
+		MailboxProperties properties = new MailboxProperties(baseUrl,
+				new MailboxAuthToken(crypto.generateUniqueId().getBytes()),
+				serverSupports,
+				new MailboxFolderId(crypto.generateUniqueId().getBytes()),
+				new MailboxFolderId(crypto.generateUniqueId().getBytes()));
+		MailboxUpdate u =
+				new MailboxUpdateWithMailbox(clientSupports, properties);
+		Group g = getContactGroup(c);
+		storeMessageReplaceLatest(txn, g.getId(), u);
+	}
+
+	/**
+	 * Sends an update message with empty properties to the given contact. The
+	 * empty update indicates for the receiving contact that we don't have any
+	 * Mailbox that they can use. It still includes the list of Mailbox API
+	 * version(s) that we support as a client.
+	 */
+	private void sendUpdateNoMailbox(Transaction txn, Contact c)
+			throws DbException {
+		Group g = getContactGroup(c);
+		MailboxUpdate u = new MailboxUpdate(clientSupports);
+		storeMessageReplaceLatest(txn, g.getId(), u);
+	}
+
+	@Nullable
+	private MailboxUpdate getUpdate(Transaction txn, Contact c, boolean local)
+			throws DbException {
+		MailboxUpdate u = null;
+		Group g = getContactGroup(c);
+		try {
+			LatestUpdate latest = findLatest(txn, g.getId(), local);
+			if (latest != null) {
+				BdfList body =
+						clientHelper.getMessageAsList(txn, latest.messageId);
+				u = parseUpdate(body);
+			}
+		} catch (FormatException e) {
+			throw new DbException(e);
+		}
+		return u;
+	}
+
+	private void storeMessageReplaceLatest(Transaction txn, GroupId g,
+			MailboxUpdate u) throws DbException {
+		try {
+			LatestUpdate latest = findLatest(txn, g, true);
+			long version = latest == null ? 1 : latest.version + 1;
+			Message m = clientHelper.createMessage(g, clock.currentTimeMillis(),
+					encodeProperties(version, u));
+			BdfDictionary meta = new BdfDictionary();
+			meta.put(MSG_KEY_VERSION, version);
+			meta.put(MSG_KEY_LOCAL, true);
+			clientHelper.addLocalMessage(txn, m, meta, true, false);
+			if (latest != null) {
+				db.removeMessage(txn, latest.messageId);
+			}
+		} catch (FormatException e) {
+			throw new DbException(e);
+		}
+	}
+
+	@Nullable
+	private LatestUpdate findLatest(Transaction txn, GroupId g, boolean local)
+			throws DbException, FormatException {
+		Map<MessageId, BdfDictionary> metadata =
+				clientHelper.getMessageMetadataAsDictionary(txn, g);
+		// We should have at most 1 local and 1 remote
+		if (metadata.size() > 2) {
+			throw new IllegalStateException();
+		}
+		for (Entry<MessageId, BdfDictionary> e : metadata.entrySet()) {
+			BdfDictionary meta = e.getValue();
+			if (meta.getBoolean(MSG_KEY_LOCAL) == local) {
+				return new LatestUpdate(e.getKey(),
+						meta.getLong(MSG_KEY_VERSION));
+			}
+		}
+		return null;
+	}
+
+	private BdfList encodeProperties(long version, MailboxUpdate u) {
+		BdfDictionary dict = new BdfDictionary();
+		BdfList serverSupports = new BdfList();
+		if (u.hasMailbox()) {
+			MailboxUpdateWithMailbox um = (MailboxUpdateWithMailbox) u;
+			MailboxProperties properties = um.getMailboxProperties();
+			serverSupports = encodeSupportsList(properties.getServerSupports());
+			dict.put(PROP_KEY_ONION, properties.getOnion());
+			dict.put(PROP_KEY_AUTHTOKEN, properties.getAuthToken());
+			dict.put(PROP_KEY_INBOXID, properties.getInboxId());
+			dict.put(PROP_KEY_OUTBOXID, properties.getOutboxId());
+		}
+		return BdfList.of(version, encodeSupportsList(u.getClientSupports()),
+				serverSupports, dict);
+	}
+
+	private BdfList encodeSupportsList(List<MailboxVersion> supportsList) {
+		BdfList supports = new BdfList();
+		for (MailboxVersion version : supportsList) {
+			supports.add(BdfList.of(version.getMajor(), version.getMinor()));
+		}
+		return supports;
+	}
+
+	private MailboxUpdate parseUpdate(BdfList body) throws FormatException {
+		BdfList clientSupports = body.getList(1);
+		BdfList serverSupports = body.getList(2);
+		BdfDictionary dict = body.getDictionary(3);
+		return clientHelper.parseAndValidateMailboxUpdate(clientSupports,
+				serverSupports, dict);
+	}
+
+	private Group getContactGroup(Contact c) {
+		return contactGroupFactory.createContactGroup(CLIENT_ID, MAJOR_VERSION,
+				c);
+	}
+
+	private static class LatestUpdate {
+
+		private final MessageId messageId;
+		private final long version;
+
+		private LatestUpdate(MessageId messageId, long version) {
+			this.messageId = messageId;
+			this.version = version;
+		}
+	}
+}

bramble-core/src/main/java/org/briarproject/bramble/mailbox/MailboxUpdateValidator.java

@@ -0,0 +1,54 @@
+package org.briarproject.bramble.mailbox;
+
+import org.briarproject.bramble.api.FormatException;
+import org.briarproject.bramble.api.client.BdfMessageContext;
+import org.briarproject.bramble.api.client.BdfMessageValidator;
+import org.briarproject.bramble.api.client.ClientHelper;
+import org.briarproject.bramble.api.data.BdfDictionary;
+import org.briarproject.bramble.api.data.BdfList;
+import org.briarproject.bramble.api.data.MetadataEncoder;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.sync.Group;
+import org.briarproject.bramble.api.sync.InvalidMessageException;
+import org.briarproject.bramble.api.sync.Message;
+import org.briarproject.bramble.api.system.Clock;
+
+import javax.annotation.concurrent.Immutable;
+
+import static org.briarproject.bramble.api.mailbox.MailboxUpdateManager.MSG_KEY_LOCAL;
+import static org.briarproject.bramble.api.mailbox.MailboxUpdateManager.MSG_KEY_VERSION;
+import static org.briarproject.bramble.util.ValidationUtils.checkSize;
+
+@Immutable
+@NotNullByDefault
+class MailboxUpdateValidator extends BdfMessageValidator {
+
+	MailboxUpdateValidator(ClientHelper clientHelper,
+			MetadataEncoder metadataEncoder, Clock clock) {
+		super(clientHelper, metadataEncoder, clock);
+	}
+
+	@Override
+	protected BdfMessageContext validateMessage(Message m, Group g,
+			BdfList body) throws InvalidMessageException, FormatException {
+		// Version, Properties, clientSupports, serverSupports
+		checkSize(body, 4);
+		// Version
+		long version = body.getLong(0);
+		if (version < 0) throw new FormatException();
+		// clientSupports
+		BdfList clientSupports = body.getList(1);
+		// serverSupports
+		BdfList serverSupports = body.getList(2);
+		// Properties
+		BdfDictionary dictionary = body.getDictionary(3);
+		clientHelper.parseAndValidateMailboxUpdate(clientSupports,
+				serverSupports, dictionary);
+		// Return the metadata
+		BdfDictionary meta = new BdfDictionary();
+		meta.put(MSG_KEY_VERSION, version);
+		meta.put(MSG_KEY_LOCAL, false);
+		return new BdfMessageContext(meta);
+	}
+
+}

bramble-core/src/main/java/org/briarproject/bramble/mailbox/OwnMailboxConnectivityChecker.java

@@ -0,0 +1,75 @@
+package org.briarproject.bramble.mailbox;
+
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.db.TransactionManager;
+import org.briarproject.bramble.api.mailbox.MailboxProperties;
+import org.briarproject.bramble.api.mailbox.MailboxSettingsManager;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.system.Clock;
+import org.briarproject.bramble.mailbox.MailboxApi.ApiException;
+
+import java.io.IOException;
+import java.util.logging.Logger;
+
+import javax.annotation.concurrent.ThreadSafe;
+
+import static java.util.logging.Level.WARNING;
+import static java.util.logging.Logger.getLogger;
+import static org.briarproject.bramble.util.LogUtils.logException;
+
+@ThreadSafe
+@NotNullByDefault
+class OwnMailboxConnectivityChecker extends ConnectivityCheckerImpl {
+
+	private static final Logger LOG =
+			getLogger(OwnMailboxConnectivityChecker.class.getName());
+
+	private final MailboxApi mailboxApi;
+	private final TransactionManager db;
+	private final MailboxSettingsManager mailboxSettingsManager;
+
+	OwnMailboxConnectivityChecker(Clock clock,
+			MailboxApiCaller mailboxApiCaller,
+			MailboxApi mailboxApi,
+			TransactionManager db,
+			MailboxSettingsManager mailboxSettingsManager) {
+		super(clock, mailboxApiCaller);
+		this.mailboxApi = mailboxApi;
+		this.db = db;
+		this.mailboxSettingsManager = mailboxSettingsManager;
+	}
+
+	@Override
+	ApiCall createConnectivityCheckTask(MailboxProperties properties) {
+		if (!properties.isOwner()) throw new IllegalArgumentException();
+		return () -> {
+			try {
+				return checkConnectivityAndStoreResult(properties);
+			} catch (DbException e) {
+				logException(LOG, WARNING, e);
+				return true; // Retry
+			}
+		};
+	}
+
+	private boolean checkConnectivityAndStoreResult(
+			MailboxProperties properties) throws DbException {
+		try {
+			if (!mailboxApi.checkStatus(properties)) throw new ApiException();
+			LOG.info("Own mailbox is reachable");
+			long now = clock.currentTimeMillis();
+			db.transaction(false, txn -> mailboxSettingsManager
+					.recordSuccessfulConnection(txn, now));
+			// Call the observers and cache the result
+			onConnectivityCheckSucceeded(now);
+			return false; // Don't retry
+		} catch (IOException | ApiException e) {
+			LOG.warning("Own mailbox is unreachable");
+			logException(LOG, WARNING, e);
+			long now = clock.currentTimeMillis();
+			db.transaction(false, txn -> mailboxSettingsManager
+					.recordFailedConnectionAttempt(txn, now));
+		}
+		return true; // Retry
+	}
+}

bramble-core/src/main/java/org/briarproject/bramble/mailbox/SimpleApiCall.java

@@ -0,0 +1,39 @@
+package org.briarproject.bramble.mailbox;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.mailbox.MailboxApi.ApiException;
+import org.briarproject.bramble.mailbox.MailboxApi.TolerableFailureException;
+
+import java.io.IOException;
+import java.util.logging.Logger;
+
+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.util.LogUtils.logException;
+
+/**
+ * Convenience class for making simple API calls that don't return values.
+ */
+@NotNullByDefault
+public abstract class SimpleApiCall implements ApiCall {
+
+	private static final Logger LOG = getLogger(SimpleApiCall.class.getName());
+
+	abstract void tryToCallApi()
+			throws IOException, ApiException, TolerableFailureException;
+
+	@Override
+	public boolean callApi() {
+		try {
+			tryToCallApi();
+			return false; // Succeeded, don't retry
+		} catch (IOException | ApiException e) {
+			logException(LOG, WARNING, e);
+			return true; // Failed, retry with backoff
+		} catch (TolerableFailureException e) {
+			logException(LOG, INFO, e);
+			return false; // Failed tolerably, don't retry
+		}
+	}
+}

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

@@ -1,5 +1,6 @@
 package org.briarproject.bramble.plugin;
 
+import org.briarproject.bramble.api.Cancellable;
 import org.briarproject.bramble.api.Pair;
 import org.briarproject.bramble.api.connection.ConnectionManager;
 import org.briarproject.bramble.api.connection.ConnectionRegistry;
@@ -27,7 +28,6 @@ import org.briarproject.bramble.api.properties.TransportProperties;
 import org.briarproject.bramble.api.properties.TransportPropertyManager;
 import org.briarproject.bramble.api.system.Clock;
 import org.briarproject.bramble.api.system.TaskScheduler;
-import org.briarproject.bramble.api.system.TaskScheduler.Cancellable;
 import org.briarproject.bramble.api.system.Wakeful;
 import org.briarproject.bramble.api.system.WakefulIoExecutor;
 

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

@@ -3,6 +3,7 @@ package org.briarproject.bramble.plugin.file;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.plugin.file.RemovableDriveTask;
 
+@Deprecated // We can simply remove tasks when they finish
 @NotNullByDefault
 interface RemovableDriveTaskRegistry {
 

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

@@ -1,40 +1,73 @@
 package org.briarproject.bramble.plugin.tor;
 
 import org.briarproject.bramble.api.lifecycle.IoExecutor;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 
 import java.util.List;
 
-// TODO: Create a module for this so it doesn't have to be public
+@NotNullByDefault
-
 public interface CircumventionProvider {
 
+	enum BridgeType {
+		DEFAULT_OBFS4,
+		NON_DEFAULT_OBFS4,
+		VANILLA,
+		MEEK
+	}
+
 	/**
 	 * Countries where Tor is blocked, i.e. vanilla Tor connection won't work.
-	 *
+	 * <p>
 	 * See https://en.wikipedia.org/wiki/ISO_3166-1_alpha-2
 	 * and https://trac.torproject.org/projects/tor/wiki/doc/OONI/censorshipwiki
 	 */
-	String[] BLOCKED = {"CN", "IR", "EG", "BY", "TR", "SY", "VE"};
+	String[] BLOCKED = {"BY", "CN", "EG", "IR", "RU", "TM", "VE"};
 
 	/**
-	 * Countries where obfs4 or meek bridge connections are likely to work.
+	 * Countries where bridge connections are likely to work.
-	 * Should be a subset of {@link #BLOCKED}.
+	 * Should be a subset of {@link #BLOCKED} and the union of
+	 * {@link #DEFAULT_BRIDGES}, {@link #NON_DEFAULT_BRIDGES} and
+	 * {@link #MEEK_BRIDGES}.
 	 */
-	String[] BRIDGES = { "CN", "IR", "EG", "BY", "TR", "SY", "VE" };
+	String[] BRIDGES = {"BY", "CN", "EG", "IR", "RU", "TM", "VE"};
 
 	/**
-	 * Countries where obfs4 bridges won't work and meek is needed.
+	 * Countries where default obfs4 or vanilla bridges are likely to work.
 	 * Should be a subset of {@link #BRIDGES}.
 	 */
-	String[] NEEDS_MEEK = {"CN", "IR"};
+	String[] DEFAULT_BRIDGES = {"EG", "VE"};
 
+	/**
+	 * Countries where non-default obfs4 or vanilla bridges are likely to work.
+	 * Should be a subset of {@link #BRIDGES}.
+	 */
+	String[] NON_DEFAULT_BRIDGES = {"BY", "RU", "TM"};
+
+	/**
+	 * Countries where obfs4 and vanilla bridges won't work and meek is needed.
+	 * Should be a subset of {@link #BRIDGES}.
+	 */
+	String[] MEEK_BRIDGES = {"CN", "IR"};
+
+	/**
+	 * Returns true if vanilla Tor connections are blocked in the given country.
+	 */
 	boolean isTorProbablyBlocked(String countryCode);
 
+	/**
+	 * Returns true if bridge connections of some type work in the given
+	 * country.
+	 */
 	boolean doBridgesWork(String countryCode);
 
-	boolean needsMeek(String countryCode);
+	/**
+	 * Returns the types of bridge connection that are suitable for the given
+	 * country, or {@link #DEFAULT_BRIDGES} if no bridge type is known
+	 * to work.
+	 */
+	List<BridgeType> getSuitableBridgeTypes(String countryCode);
 
 	@IoExecutor
-	List<String> getBridges(boolean meek);
+	List<String> getBridges(BridgeType type);
 
 }

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

@@ -1,6 +1,7 @@
 package org.briarproject.bramble.plugin.tor;
 
 import org.briarproject.bramble.api.lifecycle.IoExecutor;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 
 import java.io.InputStream;
 import java.util.ArrayList;
@@ -9,24 +10,33 @@ import java.util.List;
 import java.util.Scanner;
 import java.util.Set;
 
-import javax.annotation.Nullable;
+import javax.annotation.concurrent.Immutable;
 import javax.inject.Inject;
 
 import static java.util.Arrays.asList;
+import static java.util.Collections.singletonList;
+import static org.briarproject.bramble.api.nullsafety.NullSafety.requireNonNull;
+import static org.briarproject.bramble.plugin.tor.CircumventionProvider.BridgeType.DEFAULT_OBFS4;
+import static org.briarproject.bramble.plugin.tor.CircumventionProvider.BridgeType.MEEK;
+import static org.briarproject.bramble.plugin.tor.CircumventionProvider.BridgeType.NON_DEFAULT_OBFS4;
+import static org.briarproject.bramble.plugin.tor.CircumventionProvider.BridgeType.VANILLA;
 
+@Immutable
+@NotNullByDefault
 class CircumventionProviderImpl implements CircumventionProvider {
 
 	private final static String BRIDGE_FILE_NAME = "bridges";
 
 	private static final Set<String> BLOCKED_IN_COUNTRIES =
 			new HashSet<>(asList(BLOCKED));
-	private static final Set<String> BRIDGES_WORK_IN_COUNTRIES =
+	private static final Set<String> BRIDGE_COUNTRIES =
 			new HashSet<>(asList(BRIDGES));
-	private static final Set<String> BRIDGES_NEED_MEEK =
+	private static final Set<String> DEFAULT_OBFS4_BRIDGE_COUNTRIES =
-			new HashSet<>(asList(NEEDS_MEEK));
+			new HashSet<>(asList(DEFAULT_BRIDGES));
-
+	private static final Set<String> NON_DEFAULT_BRIDGE_COUNTRIES =
-	@Nullable
+			new HashSet<>(asList(NON_DEFAULT_BRIDGES));
-	private volatile List<String> bridges = null;
+	private static final Set<String> MEEK_COUNTRIES =
+			new HashSet<>(asList(MEEK_BRIDGES));
 
 	@Inject
 	CircumventionProviderImpl() {
@@ -39,33 +49,40 @@ class CircumventionProviderImpl implements CircumventionProvider {
 
 	@Override
 	public boolean doBridgesWork(String countryCode) {
-		return BRIDGES_WORK_IN_COUNTRIES.contains(countryCode);
+		return BRIDGE_COUNTRIES.contains(countryCode);
 	}
 
 	@Override
-	public boolean needsMeek(String countryCode) {
+	public List<BridgeType> getSuitableBridgeTypes(String countryCode) {
-		return BRIDGES_NEED_MEEK.contains(countryCode);
+		if (DEFAULT_OBFS4_BRIDGE_COUNTRIES.contains(countryCode)) {
+			return asList(DEFAULT_OBFS4, VANILLA);
+		} else if (NON_DEFAULT_BRIDGE_COUNTRIES.contains(countryCode)) {
+			return asList(NON_DEFAULT_OBFS4, VANILLA);
+		} else if (MEEK_COUNTRIES.contains(countryCode)) {
+			return singletonList(MEEK);
+		} else {
+			return asList(DEFAULT_OBFS4, VANILLA);
+		}
 	}
 
 	@Override
 	@IoExecutor
-	public List<String> getBridges(boolean useMeek) {
+	public List<String> getBridges(BridgeType type) {
-		List<String> bridges = this.bridges;
+		InputStream is = requireNonNull(getClass().getClassLoader()
-		if (bridges != null) return new ArrayList<>(bridges);
+				.getResourceAsStream(BRIDGE_FILE_NAME));
-
-		InputStream is = getClass().getClassLoader()
-				.getResourceAsStream(BRIDGE_FILE_NAME);
 		Scanner scanner = new Scanner(is);
 
-		bridges = new ArrayList<>();
+		List<String> bridges = new ArrayList<>();
 		while (scanner.hasNextLine()) {
 			String line = scanner.nextLine();
-			boolean isMeekBridge = line.startsWith("Bridge meek");
+			if ((type == DEFAULT_OBFS4 && line.startsWith("d ")) ||
-			if (useMeek && !isMeekBridge || !useMeek && isMeekBridge) continue;
+					(type == NON_DEFAULT_OBFS4 && line.startsWith("n ")) ||
-			if (!line.startsWith("#")) bridges.add(line);
+					(type == VANILLA && line.startsWith("v ")) ||
+					(type == MEEK && line.startsWith("m "))) {
+				bridges.add(line.substring(2));
+			}
 		}
 		scanner.close();
-		this.bridges = bridges;
 		return bridges;
 	}
 

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

@@ -2,6 +2,7 @@ package org.briarproject.bramble.plugin.tor;
 
 import net.freehaven.tor.control.EventHandler;
 import net.freehaven.tor.control.TorControlConnection;
+import net.freehaven.tor.control.TorNotRunningException;
 
 import org.briarproject.bramble.PoliteExecutor;
 import org.briarproject.bramble.api.Pair;
@@ -33,6 +34,7 @@ import org.briarproject.bramble.api.settings.event.SettingsUpdatedEvent;
 import org.briarproject.bramble.api.system.Clock;
 import org.briarproject.bramble.api.system.LocationUtils;
 import org.briarproject.bramble.api.system.ResourceProvider;
+import org.briarproject.bramble.plugin.tor.CircumventionProvider.BridgeType;
 
 import java.io.ByteArrayInputStream;
 import java.io.EOFException;
@@ -79,23 +81,21 @@ import static org.briarproject.bramble.api.plugin.TorConstants.DEFAULT_PREF_PLUG
 import static org.briarproject.bramble.api.plugin.TorConstants.DEFAULT_PREF_TOR_MOBILE;
 import static org.briarproject.bramble.api.plugin.TorConstants.DEFAULT_PREF_TOR_NETWORK;
 import static org.briarproject.bramble.api.plugin.TorConstants.DEFAULT_PREF_TOR_ONLY_WHEN_CHARGING;
-import static org.briarproject.bramble.api.plugin.TorConstants.HS_PRIVATE_KEY_V2;
 import static org.briarproject.bramble.api.plugin.TorConstants.HS_PRIVATE_KEY_V3;
-import static org.briarproject.bramble.api.plugin.TorConstants.HS_V3_CREATED;
 import static org.briarproject.bramble.api.plugin.TorConstants.ID;
 import static org.briarproject.bramble.api.plugin.TorConstants.PREF_TOR_MOBILE;
 import static org.briarproject.bramble.api.plugin.TorConstants.PREF_TOR_NETWORK;
 import static org.briarproject.bramble.api.plugin.TorConstants.PREF_TOR_NETWORK_AUTOMATIC;
-import static org.briarproject.bramble.api.plugin.TorConstants.PREF_TOR_NETWORK_NEVER;
 import static org.briarproject.bramble.api.plugin.TorConstants.PREF_TOR_NETWORK_WITH_BRIDGES;
 import static org.briarproject.bramble.api.plugin.TorConstants.PREF_TOR_ONLY_WHEN_CHARGING;
 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.V3_MIGRATION_PERIOD_MS;
+import static org.briarproject.bramble.plugin.tor.CircumventionProvider.BridgeType.DEFAULT_OBFS4;
+import static org.briarproject.bramble.plugin.tor.CircumventionProvider.BridgeType.MEEK;
+import static org.briarproject.bramble.plugin.tor.CircumventionProvider.BridgeType.NON_DEFAULT_OBFS4;
 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;
@@ -110,12 +110,18 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 	private static final Logger LOG = getLogger(TorPlugin.class.getName());
 
 	private static final String[] EVENTS = {
-			"CIRC", "ORCONN", "HS_DESC", "NOTICE", "WARN", "ERR"
+			"CIRC",
+			"ORCONN",
+			"STATUS_GENERAL",
+			"STATUS_CLIENT",
+			"HS_DESC",
+			"NOTICE",
+			"WARN",
+			"ERR"
 	};
 	private static final String OWNER = "__OwningControllerProcess";
 	private static final int COOKIE_TIMEOUT_MS = 3000;
 	private static final int COOKIE_POLLING_INTERVAL_MS = 200;
-	private static final Pattern ONION_V2 = Pattern.compile("[a-z2-7]{16}");
 	private static final Pattern ONION_V3 = Pattern.compile("[a-z2-7]{56}");
 
 	private final Executor ioExecutor, wakefulIoExecutor;
@@ -135,8 +141,8 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 	private final int maxIdleTime;
 	private final int socketTimeout;
 	private final File torDirectory, geoIpFile, configFile;
-	private int torSocksPort;
+	private final int torSocksPort;
-	private int torControlPort;
+	private final int torControlPort;
 	private final File doneFile, cookieFile;
 	private final AtomicBoolean used = new AtomicBoolean(false);
 
@@ -231,7 +237,7 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 			}
 		}
 		// Load the settings
-		settings = migrateSettings(callback.getSettings());
+		settings = callback.getSettings();
 		// Install or update the assets if necessary
 		if (!assetsAreUpToDate()) installAssets();
 		if (cookieFile.exists() && !cookieFile.delete())
@@ -284,6 +290,7 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 					if (LOG.isLoggable(INFO)) listFiles(torDirectory);
 					throw new PluginException();
 				}
+				//noinspection BusyWait
 				Thread.sleep(COOKIE_POLLING_INTERVAL_MS);
 			}
 			LOG.info("Auth cookie created");
@@ -304,11 +311,19 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 			controlConnection.setEventHandler(this);
 			controlConnection.setEvents(asList(EVENTS));
 			// Check whether Tor has already bootstrapped
-			String phase = controlConnection.getInfo("status/bootstrap-phase");
+			String info = controlConnection.getInfo("status/bootstrap-phase");
-			if (phase != null && phase.contains("PROGRESS=100")) {
+			if (info != null && info.contains("PROGRESS=100")) {
 				LOG.info("Tor has already bootstrapped");
 				state.setBootstrapped();
 			}
+			// Check whether Tor has already built a circuit
+			info = controlConnection.getInfo("status/circuit-established");
+			if ("1".equals(info)) {
+				LOG.info("Tor has already built a circuit");
+				state.getAndSetCircuitBuilt(true);
+			}
+		} catch (TorNotRunningException e) {
+			throw new RuntimeException(e);
 		} catch (IOException e) {
 			throw new PluginException(e);
 		}
@@ -320,18 +335,6 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 		bind();
 	}
 
-	// TODO: Remove after a reasonable migration period (added 2020-06-25)
-	private Settings migrateSettings(Settings settings) {
-		int network = settings.getInt(PREF_TOR_NETWORK,
-				DEFAULT_PREF_TOR_NETWORK);
-		if (network == PREF_TOR_NETWORK_NEVER) {
-			settings.putInt(PREF_TOR_NETWORK, DEFAULT_PREF_TOR_NETWORK);
-			settings.putBoolean(PREF_PLUGIN_ENABLE, false);
-			callback.mergeSettings(settings);
-		}
-		return settings;
-	}
-
 	private boolean assetsAreUpToDate() {
 		return doneFile.lastModified() > getLastUpdateTime();
 	}
@@ -341,9 +344,14 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 			// The done file may already exist from a previous installation
 			//noinspection ResultOfMethodCallIgnored
 			doneFile.delete();
+			// The GeoIP file may exist from a previous installation - we can
+			// save some space by deleting it.
+			// TODO: Remove after a reasonable migration period
+			//  (added 2022-03-29)
+			//noinspection ResultOfMethodCallIgnored
+			geoIpFile.delete();
 			installTorExecutable();
 			installObfs4Executable();
-			extract(getGeoIpInputStream(), geoIpFile);
 			extract(getConfigInputStream(), configFile);
 			if (!doneFile.createNewFile())
 				LOG.warning("Failed to create done file");
@@ -381,14 +389,6 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 		return zin;
 	}
 
-	private InputStream getGeoIpInputStream() throws IOException {
-		InputStream in = resourceProvider.getResourceInputStream("geoip",
-				".zip");
-		ZipInputStream zin = new ZipInputStream(in);
-		if (zin.getNextEntry() == null) throw new IOException();
-		return zin;
-	}
-
 	private InputStream getObfs4InputStream() throws IOException {
 		InputStream in = resourceProvider
 				.getResourceInputStream("obfs4proxy_" + architecture, ".zip");
@@ -412,6 +412,7 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 		append(strb, "RunAsDaemon", 1);
 		append(strb, "SafeSocks", 1);
 		append(strb, "SocksPort", torSocksPort);
+		//noinspection CharsetObjectCanBeUsed
 		return new ByteArrayInputStream(
 				strb.toString().getBytes(Charset.forName("UTF-8")));
 	}
@@ -478,54 +479,10 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 
 	private void publishHiddenService(String port) {
 		if (!state.isTorRunning()) return;
-		// TODO: Remove support for v2 hidden services after a reasonable
-		// migration period (migration started 2020-06-30)
-		String privKey2 = settings.get(HS_PRIVATE_KEY_V2);
 		String privKey3 = settings.get(HS_PRIVATE_KEY_V3);
-		String v3Created = settings.get(HS_V3_CREATED);
-		// Publish a v2 hidden service if we've already created one, and
-		// either we've never published a v3 hidden service or we're still
-		// in the migration period since first publishing it
-		if (!isNullOrEmpty(privKey2)) {
-			long now = clock.currentTimeMillis();
-			long then = v3Created == null ? now : Long.parseLong(v3Created);
-			if (now - then >= V3_MIGRATION_PERIOD_MS) retireV2HiddenService();
-			else publishV2HiddenService(port, privKey2);
-		}
 		publishV3HiddenService(port, privKey3);
 	}
 
-	private void publishV2HiddenService(String port, String privKey) {
-		LOG.info("Creating v2 hidden service");
-		Map<Integer, String> portLines = singletonMap(80, "127.0.0.1:" + port);
-		Map<String, String> response;
-		try {
-			response = controlConnection.addOnion(privKey, portLines);
-		} catch (IOException e) {
-			logException(LOG, WARNING, e);
-			return;
-		}
-		if (!response.containsKey(HS_ADDRESS)) {
-			LOG.warning("Tor did not return a hidden service address");
-			return;
-		}
-		String onion2 = response.get(HS_ADDRESS);
-		if (LOG.isLoggable(INFO)) {
-			LOG.info("V2 hidden service " + scrubOnion(onion2));
-		}
-		// The hostname has already been published and the private key stored
-	}
-
-	private void retireV2HiddenService() {
-		LOG.info("Retiring v2 hidden service");
-		TransportProperties p = new TransportProperties();
-		p.put(PROP_ONION_V2, "");
-		callback.mergeLocalProperties(p);
-		Settings s = new Settings();
-		s.put(HS_PRIVATE_KEY_V2, "");
-		callback.mergeSettings(s);
-	}
-
 	private void publishV3HiddenService(String port, @Nullable String privKey) {
 		LOG.info("Creating v3 hidden service");
 		Map<Integer, String> portLines = singletonMap(80, "127.0.0.1:" + port);
@@ -538,6 +495,8 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 			} else {
 				response = controlConnection.addOnion(privKey, portLines);
 			}
+		} catch (TorNotRunningException e) {
+			throw new RuntimeException(e);
 		} catch (IOException e) {
 			logException(LOG, WARNING, e);
 			return;
@@ -562,7 +521,6 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 			// Save the hidden service's private key for next time
 			Settings s = new Settings();
 			s.put(HS_PRIVATE_KEY_V3, response.get(HS_PRIVKEY));
-			s.put(HS_V3_CREATED, String.valueOf(clock.currentTimeMillis()));
 			callback.mergeSettings(s);
 		}
 	}
@@ -587,26 +545,38 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 
 	protected void enableNetwork(boolean enable) throws IOException {
 		state.enableNetwork(enable);
-		controlConnection.setConf("DisableNetwork", enable ? "0" : "1");
+		try {
+			controlConnection.setConf("DisableNetwork", enable ? "0" : "1");
+		} catch (TorNotRunningException e) {
+			throw new RuntimeException(e);
+		}
 	}
 
-	private void enableBridges(boolean enable, boolean needsMeek)
+	private void enableBridges(boolean enable, List<BridgeType> bridgeTypes)
 			throws IOException {
-		if (enable) {
+		try {
-			Collection<String> conf = new ArrayList<>();
+			if (enable) {
-			conf.add("UseBridges 1");
+				Collection<String> conf = new ArrayList<>();
-			File obfs4File = getObfs4ExecutableFile();
+				conf.add("UseBridges 1");
-			if (needsMeek) {
+				File obfs4File = getObfs4ExecutableFile();
-				conf.add("ClientTransportPlugin meek_lite exec " +
+				if (bridgeTypes.contains(MEEK)) {
-						obfs4File.getAbsolutePath());
+					conf.add("ClientTransportPlugin meek_lite exec " +
+							obfs4File.getAbsolutePath());
+				}
+				if (bridgeTypes.contains(DEFAULT_OBFS4) ||
+						bridgeTypes.contains(NON_DEFAULT_OBFS4)) {
+					conf.add("ClientTransportPlugin obfs4 exec " +
+							obfs4File.getAbsolutePath());
+				}
+				for (BridgeType bridgeType : bridgeTypes) {
+					conf.addAll(circumventionProvider.getBridges(bridgeType));
+				}
+				controlConnection.setConf(conf);
 			} else {
-				conf.add("ClientTransportPlugin obfs4 exec " +
+				controlConnection.setConf("UseBridges", "0");
-						obfs4File.getAbsolutePath());
 			}
-			conf.addAll(circumventionProvider.getBridges(needsMeek));
+		} catch (TorNotRunningException e) {
-			controlConnection.setConf(conf);
+			throw new RuntimeException(e);
-		} else {
-			controlConnection.setConf("UseBridges", "0");
 		}
 	}
 
@@ -620,6 +590,8 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 				controlConnection.setConf("DisableNetwork", "1");
 				controlConnection.shutdownTor("TERM");
 				controlSocket.close();
+			} catch (TorNotRunningException e) {
+				throw new RuntimeException(e);
 			} catch (IOException e) {
 				logException(LOG, WARNING, e);
 			}
@@ -669,49 +641,30 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 	@Override
 	public DuplexTransportConnection createConnection(TransportProperties p) {
 		if (getState() != ACTIVE) return null;
-		// TODO: Remove support for v2 hidden services after a reasonable
-		// migration period (migration started 2020-06-30)
-		String bestOnion = null, version = null;
-		String onion2 = p.get(PROP_ONION_V2);
 		String onion3 = p.get(PROP_ONION_V3);
-		if (!isNullOrEmpty(onion2)) {
+		if (onion3 != null && !ONION_V3.matcher(onion3).matches()) {
-			if (ONION_V2.matcher(onion2).matches()) {
+			// Don't scrub the address so we can find the problem
-				bestOnion = onion2;
+			if (LOG.isLoggable(INFO)) {
-				version = "v2";
+				LOG.info("Invalid v3 hostname: " + onion3);
-			} else {
-				// Don't scrub the address so we can find the problem
-				if (LOG.isLoggable(INFO))
-					LOG.info("Invalid v2 hostname: " + onion2);
 			}
+			onion3 = null;
 		}
-		if (!isNullOrEmpty(onion3)) {
+		if (onion3 == null) return null;
-			if (ONION_V3.matcher(onion3).matches()) {
-				bestOnion = onion3;
-				version = "v3";
-			} else {
-				// Don't scrub the address so we can find the problem
-				if (LOG.isLoggable(INFO))
-					LOG.info("Invalid v3 hostname: " + onion3);
-			}
-		}
-		if (bestOnion == null) return null;
 		Socket s = null;
 		try {
 			if (LOG.isLoggable(INFO)) {
-				LOG.info("Connecting to " + version + " "
+				LOG.info("Connecting to v3 " + scrubOnion(onion3));
-						+ scrubOnion(bestOnion));
 			}
-			s = torSocketFactory.createSocket(bestOnion + ".onion", 80);
+			s = torSocketFactory.createSocket(onion3 + ".onion", 80);
 			s.setSoTimeout(socketTimeout);
 			if (LOG.isLoggable(INFO)) {
-				LOG.info("Connected to " + version + " "
+				LOG.info("Connected to v3 " + scrubOnion(onion3));
-						+ scrubOnion(bestOnion));
 			}
 			return new TorTransportConnection(this, s);
 		} catch (IOException e) {
 			if (LOG.isLoggable(INFO)) {
-				LOG.info("Could not connect to " + version + " "
+				LOG.info("Could not connect to v3 "
-						+ scrubOnion(bestOnion) + ": " + e.toString());
+						+ scrubOnion(onion3) + ": " + e);
 			}
 			tryToClose(s, LOG, WARNING);
 			return null;
@@ -747,8 +700,8 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 		byte[] localSeed = alice ? aliceSeed : bobSeed;
 		byte[] remoteSeed = alice ? bobSeed : aliceSeed;
 		String blob = torRendezvousCrypto.getPrivateKeyBlob(localSeed);
-		String localOnion = torRendezvousCrypto.getOnionAddress(localSeed);
+		String localOnion = torRendezvousCrypto.getOnion(localSeed);
-		String remoteOnion = torRendezvousCrypto.getOnionAddress(remoteSeed);
+		String remoteOnion = torRendezvousCrypto.getOnion(remoteSeed);
 		TransportProperties remoteProperties = new TransportProperties();
 		remoteProperties.put(PROP_ONION_V3, remoteOnion);
 		try {
@@ -770,7 +723,11 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 			});
 			Map<Integer, String> portLines =
 					singletonMap(80, "127.0.0.1:" + port);
-			controlConnection.addOnion(blob, portLines);
+			try {
+				controlConnection.addOnion(blob, portLines);
+			} catch (TorNotRunningException e) {
+				throw new RuntimeException(e);
+			}
 			return new RendezvousEndpoint() {
 
 				@Override
@@ -780,7 +737,11 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 
 				@Override
 				public void close() throws IOException {
-					controlConnection.delOnion(localOnion);
+					try {
+						controlConnection.delOnion(localOnion);
+					} catch (TorNotRunningException e) {
+						throw new RuntimeException(e);
+					}
 					tryToClose(ss, LOG, WARNING);
 				}
 			};
@@ -792,9 +753,10 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 
 	@Override
 	public void circuitStatus(String status, String id, String path) {
-		if (status.equals("BUILT") &&
+		// In case of races between receiving CIRCUIT_ESTABLISHED and setting
-				state.getAndSetCircuitBuilt()) {
+		// DisableNetwork, set our circuitBuilt flag if not already set
-			LOG.info("First circuit built");
+		if (status.equals("BUILT") && !state.getAndSetCircuitBuilt(true)) {
+			LOG.info("Circuit built");
 			backoff.reset();
 		}
 	}
@@ -805,13 +767,10 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 
 	@Override
 	public void orConnStatus(String status, String orName) {
-		if (LOG.isLoggable(INFO))
+		if (LOG.isLoggable(INFO)) LOG.info("OR connection " + status);
-			LOG.info("OR connection " + status + " " + orName);
+
-		if (status.equals("CLOSED") || status.equals("FAILED")) {
+		if (status.equals("CONNECTED")) state.onOrConnectionConnected();
-			// Check whether we've lost connectivity
+		else if (status.equals("CLOSED")) state.onOrConnectionClosed();
-			updateConnectionStatus(networkManager.getNetworkStatus(),
-					batteryManager.isCharging());
-		}
 	}
 
 	@Override
@@ -825,24 +784,78 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 	@Override
 	public void message(String severity, String msg) {
 		if (LOG.isLoggable(INFO)) LOG.info(severity + " " + msg);
-		if (severity.equals("NOTICE") && msg.startsWith("Bootstrapped 100%")) {
-			state.setBootstrapped();
-			backoff.reset();
-		}
 	}
 
 	@Override
 	public void unrecognized(String type, String msg) {
-		if (type.equals("HS_DESC") && msg.startsWith("UPLOADED")) {
+		if (type.equals("STATUS_CLIENT")) {
-			if (LOG.isLoggable(INFO)) {
+			handleClientStatus(removeSeverity(msg));
-				String[] words = msg.split(" ");
+		} else if (type.equals("STATUS_GENERAL")) {
-				if (words.length > 1 && ONION_V3.matcher(words[1]).matches()) {
+			handleGeneralStatus(removeSeverity(msg));
-					LOG.info("V3 descriptor uploaded");
+		} else if (type.equals("HS_DESC") && msg.startsWith("UPLOADED")) {
-				} else {
+			String[] parts = msg.split(" ");
-					LOG.info("V2 descriptor uploaded");
+			if (parts.length < 2) {
+				LOG.warning("Failed to parse HS_DESC UPLOADED event");
+			} else if (LOG.isLoggable(INFO)) {
+				LOG.info("V3 descriptor uploaded for " + scrubOnion(parts[1]));
+			}
+		}
+	}
+
+	private String removeSeverity(String msg) {
+		return msg.replaceFirst("[^ ]+ ", "");
+	}
+
+	private void handleClientStatus(String msg) {
+		if (msg.startsWith("BOOTSTRAP PROGRESS=100")) {
+			LOG.info("Bootstrapped");
+			state.setBootstrapped();
+			backoff.reset();
+		} else if (msg.startsWith("CIRCUIT_ESTABLISHED")) {
+			if (!state.getAndSetCircuitBuilt(true)) {
+				LOG.info("Circuit built");
+				backoff.reset();
+			}
+		} else if (msg.startsWith("CIRCUIT_NOT_ESTABLISHED")) {
+			if (state.getAndSetCircuitBuilt(false)) {
+				LOG.info("Circuit not built");
+				// TODO: Disable and re-enable network to prompt Tor to rebuild
+				//  its guard/bridge connections? This will also close any
+				//  established circuits, which might still be functioning
+			}
+		}
+	}
+
+	private void handleGeneralStatus(String msg) {
+		if (msg.startsWith("CLOCK_JUMPED")) {
+			Long time = parseLongArgument(msg, "TIME");
+			if (time != null && LOG.isLoggable(WARNING)) {
+				LOG.warning("Clock jumped " + time + " seconds");
+			}
+		} else if (msg.startsWith("CLOCK_SKEW")) {
+			Long skew = parseLongArgument(msg, "SKEW");
+			if (skew != null && LOG.isLoggable(WARNING)) {
+				LOG.warning("Clock is skewed by " + skew + " seconds");
+			}
+		}
+	}
+
+	@Nullable
+	private Long parseLongArgument(String msg, String argName) {
+		String[] args = msg.split(" ");
+		for (String arg : args) {
+			if (arg.startsWith(argName + "=")) {
+				try {
+					return Long.parseLong(arg.substring(argName.length() + 1));
+				} catch (NumberFormatException e) {
+					break;
 				}
 			}
 		}
+		if (LOG.isLoggable(WARNING)) {
+			LOG.warning("Failed to parse " + argName + " from '" + msg + "'");
+		}
+		return null;
 	}
 
 	@Override
@@ -852,11 +865,6 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 			if (s.getNamespace().equals(ID.getString())) {
 				LOG.info("Tor settings updated");
 				settings = s.getSettings();
-				// Works around a bug introduced in Tor 0.3.4.8.
-				// https://trac.torproject.org/projects/tor/ticket/28027
-				// Could be replaced with callback.transportDisabled()
-				// when fixed.
-				disableNetwork();
 				updateConnectionStatus(networkManager.getNetworkStatus(),
 						batteryManager.isCharging());
 			}
@@ -869,16 +877,6 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 		}
 	}
 
-	private void disableNetwork() {
-		connectionStatusExecutor.execute(() -> {
-			try {
-				if (state.isTorRunning()) enableNetwork(false);
-			} catch (IOException ex) {
-				logException(LOG, WARNING, ex);
-			}
-		});
-	}
-
 	private void updateConnectionStatus(NetworkStatus status,
 			boolean charging) {
 		connectionStatusExecutor.execute(() -> {
@@ -911,7 +909,9 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 
 			int reasonsDisabled = 0;
 			boolean enableNetwork = false, enableBridges = false;
-			boolean useMeek = false, enableConnectionPadding = false;
+			boolean enableConnectionPadding = false;
+			List<BridgeType> bridgeTypes =
+					circumventionProvider.getSuitableBridgeTypes(country);
 
 			if (!online) {
 				LOG.info("Disabling network, device is offline");
@@ -940,14 +940,10 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 					enableNetwork = true;
 					if (network == PREF_TOR_NETWORK_WITH_BRIDGES ||
 							(automatic && bridgesWork)) {
-						if (ipv6Only ||
+						if (ipv6Only) bridgeTypes = singletonList(MEEK);
-								circumventionProvider.needsMeek(country)) {
+						enableBridges = true;
-							LOG.info("Using meek bridges");
+						if (LOG.isLoggable(INFO)) {
-							enableBridges = true;
+							LOG.info("Using bridge types " + bridgeTypes);
-							useMeek = true;
-						} else {
-							LOG.info("Using obfs4 bridges");
-							enableBridges = true;
 						}
 					} else {
 						LOG.info("Not using bridges");
@@ -965,7 +961,7 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 
 			try {
 				if (enableNetwork) {
-					enableBridges(enableBridges, useMeek);
+					enableBridges(enableBridges, bridgeTypes);
 					enableConnectionPadding(enableConnectionPadding);
 					useIpv6(ipv6Only);
 				}
@@ -977,12 +973,20 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 	}
 
 	private void enableConnectionPadding(boolean enable) throws IOException {
-		controlConnection.setConf("ConnectionPadding", enable ? "1" : "0");
+		try {
+			controlConnection.setConf("ConnectionPadding", enable ? "1" : "0");
+		} catch (TorNotRunningException e) {
+			throw new RuntimeException(e);
+		}
 	}
 
 	private void useIpv6(boolean ipv6Only) throws IOException {
-		controlConnection.setConf("ClientUseIPv4", ipv6Only ? "0" : "1");
+		try {
-		controlConnection.setConf("ClientUseIPv6", ipv6Only ? "1" : "0");
+			controlConnection.setConf("ClientUseIPv4", ipv6Only ? "0" : "1");
+			controlConnection.setConf("ClientUseIPv6", ipv6Only ? "1" : "0");
+		} catch (TorNotRunningException e) {
+			throw new RuntimeException(e);
+		}
 	}
 
 	@ThreadSafe
@@ -1005,17 +1009,21 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 		@Nullable
 		private ServerSocket serverSocket = null;
 
-		synchronized void setStarted() {
+		@GuardedBy("this")
+		private int orConnectionsConnected = 0;
+
+		private synchronized void setStarted() {
 			started = true;
 			callback.pluginStateChanged(getState());
 		}
 
-		synchronized boolean isTorRunning() {
+		@SuppressWarnings("BooleanMethodIsAlwaysInverted")
+		private synchronized boolean isTorRunning() {
 			return started && !stopped;
 		}
 
 		@Nullable
-		synchronized ServerSocket setStopped() {
+		private synchronized ServerSocket setStopped() {
 			stopped = true;
 			ServerSocket ss = serverSocket;
 			serverSocket = null;
@@ -1023,55 +1031,83 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 			return ss;
 		}
 
-		synchronized void setBootstrapped() {
+		private synchronized void setBootstrapped() {
 			bootstrapped = true;
 			callback.pluginStateChanged(getState());
 		}
 
-		synchronized boolean getAndSetCircuitBuilt() {
+		private synchronized boolean getAndSetCircuitBuilt(boolean built) {
-			boolean firstCircuit = !circuitBuilt;
+			boolean old = circuitBuilt;
-			circuitBuilt = true;
+			circuitBuilt = built;
-			callback.pluginStateChanged(getState());
+			if (built != old) callback.pluginStateChanged(getState());
-			return firstCircuit;
+			return old;
 		}
 
-		synchronized void enableNetwork(boolean enable) {
+		private synchronized void enableNetwork(boolean enable) {
 			networkInitialised = true;
 			networkEnabled = enable;
 			if (!enable) circuitBuilt = false;
 			callback.pluginStateChanged(getState());
 		}
 
-		synchronized void setReasonsDisabled(int reasonsDisabled) {
+		private synchronized void setReasonsDisabled(int reasonsDisabled) {
 			settingsChecked = true;
 			this.reasonsDisabled = reasonsDisabled;
 			callback.pluginStateChanged(getState());
 		}
 
 		// Doesn't affect getState()
-		synchronized boolean setServerSocket(ServerSocket ss) {
+		private synchronized boolean setServerSocket(ServerSocket ss) {
 			if (stopped || serverSocket != null) return false;
 			serverSocket = ss;
 			return true;
 		}
 
 		// Doesn't affect getState()
-		synchronized void clearServerSocket(ServerSocket ss) {
+		private synchronized void clearServerSocket(ServerSocket ss) {
 			if (serverSocket == ss) serverSocket = null;
 		}
 
-		synchronized State getState() {
+		private synchronized State getState() {
 			if (!started || stopped || !settingsChecked) {
 				return STARTING_STOPPING;
 			}
 			if (reasonsDisabled != 0) return DISABLED;
 			if (!networkInitialised) return ENABLING;
 			if (!networkEnabled) return INACTIVE;
-			return bootstrapped && circuitBuilt ? ACTIVE : ENABLING;
+			return bootstrapped && circuitBuilt && orConnectionsConnected > 0
+					? ACTIVE : ENABLING;
 		}
 
-		synchronized int getReasonsDisabled() {
+		private synchronized int getReasonsDisabled() {
 			return getState() == DISABLED ? reasonsDisabled : 0;
 		}
+
+		private synchronized void onOrConnectionConnected() {
+			int oldConnected = orConnectionsConnected;
+			orConnectionsConnected++;
+			logOrConnections();
+			if (oldConnected == 0) callback.pluginStateChanged(getState());
+		}
+
+		private synchronized void onOrConnectionClosed() {
+			int oldConnected = orConnectionsConnected;
+			orConnectionsConnected--;
+			if (orConnectionsConnected < 0) {
+				LOG.warning("Count was zero before connection closed");
+				orConnectionsConnected = 0;
+			}
+			logOrConnections();
+			if (orConnectionsConnected == 0 && oldConnected != 0) {
+				callback.pluginStateChanged(getState());
+			}
+		}
+
+		@GuardedBy("this")
+		private void logOrConnections() {
+			if (LOG.isLoggable(INFO)) {
+				LOG.info(orConnectionsConnected + " OR connections connected");
+			}
+		}
 	}
 }