Bump version numbers for 1.3.6 release.

Transfer data securely via removable storage

See merge request briar/briar!1511

.gitignore

@@ -18,6 +18,7 @@ local.properties
 
 # Android Studio
 .idea/*
+!.idea/inspectionProfiles/
 !.idea/runConfigurations/
 !.idea/codeStyleSettings.xml
 !.idea/codeStyles

.gitlab-ci.yml

@@ -1,30 +1,79 @@
 image: briar/ci-image-android:latest
 
 stages:
-- test
-- optional_tests
-- check_reproducibility
+  - test
+  - optional_tests
+  - check_reproducibility
 
-test:
-  stage: test
+workflow:
+  # when to create a CI pipeline
+  rules:
+    - if: '$CI_PIPELINE_SOURCE == "merge_request_event"'
+    - if: '$CI_COMMIT_BRANCH && $CI_OPEN_MERGE_REQUESTS'
+      when: never # avoids duplicate jobs for branch and MR
+    - if: '$CI_COMMIT_BRANCH'
+    - if: '$CI_COMMIT_TAG'
+
+.base-test:
   before_script:
     - set -e
     - export GRADLE_USER_HOME=$PWD/.gradle
-
   cache:
+    key: "$CI_COMMIT_REF_SLUG"
     paths:
       - .gradle/wrapper
       - .gradle/caches
-
-  script:
-    - ./gradlew --no-daemon -Djava.security.egd=file:/dev/urandom animalSnifferMain animalSnifferTest
-    - ./gradlew --no-daemon -Djava.security.egd=file:/dev/urandom check compileOfficialDebugAndroidTestSources compileScreenshotDebugAndroidTestSources
-
   after_script:
-    # these file change every time but should not be cached
+    # these file change every time and should not be cached
     - rm -f $GRADLE_USER_HOME/caches/modules-2/modules-2.lock
     - rm -fr $GRADLE_USER_HOME/caches/*/plugin-resolution/
 
+test:
+  extends: .base-test
+  stage: test
+  script:
+    - ./gradlew --no-daemon -Djava.security.egd=file:/dev/urandom animalSnifferMain animalSnifferTest
+    - ./gradlew --no-daemon -Djava.security.egd=file:/dev/urandom check
+  rules:
+    - if: '$CI_PIPELINE_SOURCE == "merge_request_event"'
+      when: always
+    - when: always
+
+android test:
+  extends: .base-test
+  stage: optional_tests
+  image: briar/ci-image-android-emulator:latest
+  script:
+    # start emulator first, so it can fail early
+    - start-emulator.sh
+    # run normal and screenshot tests together (exclude Large tests)
+    - ./gradlew -Djava.security.egd=file:/dev/urandom connectedAndroidTest -Pandroid.testInstrumentationRunnerArguments.package=org.briarproject.briar.android -Pandroid.testInstrumentationRunnerArguments.notAnnotation=androidx.test.filters.LargeTest
+  after_script:
+    - adb pull /sdcard/Pictures/screenshots
+  artifacts:
+    name: "${CI_PROJECT_PATH}_${CI_JOB_STAGE}_${CI_COMMIT_REF_NAME}_${CI_COMMIT_SHA}"
+    paths:
+      - kernel.log
+      - logcat.txt
+      - briar-android/build/reports/androidTests/connected/flavors/*
+      - screenshots
+    expire_in: 3 days
+    when: on_failure
+  rules:
+    - if: '$CI_PIPELINE_SOURCE == "schedule"'
+      when: on_success
+    - if: '$CI_PIPELINE_SOURCE == "merge_request_event"'
+      changes:
+        - briar-android/**/*
+      when: manual
+      allow_failure: true
+    - if: '$CI_COMMIT_TAG == null'
+      when: manual
+      allow_failure: true
+  retry:
+    max: 1
+  tags:
+    - kvm
 
 test_reproducible:
   stage: check_reproducibility
@@ -40,6 +89,7 @@ test_reproducible:
     - export GRADLE_USER_HOME=$PWD/.gradle
 
   cache:
+    key: "$CI_COMMIT_REF_SLUG"
     paths:
       - .gradle/wrapper
       - .gradle/caches
@@ -52,11 +102,15 @@ test_reproducible:
     - rm -f $GRADLE_USER_HOME/caches/modules-2/modules-2.lock
     - rm -fr $GRADLE_USER_HOME/caches/*/plugin-resolution/
 
-manual_tests:
+bridge test:
   extends: .optional_tests
-  when: manual
-  except:
-    - tags
+  rules:
+    - if: '$CI_PIPELINE_SOURCE == "schedule"'
+      when: on_success
+      allow_failure: true
+    - if: '$CI_COMMIT_TAG == null'
+      when: manual
+      allow_failure: true
 
 pre_release_tests:
   extends: .optional_tests

.idea/dictionaries/briar.xml

@@ -7,6 +7,7 @@
       <w>encrypter</w>
       <w>identicon</w>
       <w>introducee</w>
+      <w>introducees</w>
       <w>introducer</w>
       <w>onboarding</w>
     </words>

.idea/inspectionProfiles/Project_Default.xml

@@ -0,0 +1,14 @@
+<component name="InspectionProjectProfileManager">
+  <profile version="1.0">
+    <option name="myName" value="Project Default" />
+    <inspection_tool class="MissingOverrideAnnotation" enabled="true" level="WARNING" enabled_by_default="true">
+      <option name="ignoreObjectMethods" value="true" />
+      <option name="ignoreAnonymousClassMethods" value="false" />
+    </inspection_tool>
+    <inspection_tool class="WeakerAccess" enabled="true" level="WARNING" enabled_by_default="true">
+      <option name="SUGGEST_PACKAGE_LOCAL_FOR_MEMBERS" value="true" />
+      <option name="SUGGEST_PACKAGE_LOCAL_FOR_TOP_CLASSES" value="true" />
+      <option name="SUGGEST_PRIVATE_FOR_INNERS" value="true" />
+    </inspection_tool>
+  </profile>
+</component>

.idea/runConfigurations/Instrumentation_Tests__destroys_DB_.xml

@@ -0,0 +1,51 @@
+<component name="ProjectRunConfigurationManager">
+  <configuration default="false" name="Instrumentation Tests (destroys DB)" type="AndroidTestRunConfigurationType" factoryName="Android Instrumented Tests">
+    <module name="briar.briar-android" />
+    <option name="TESTING_TYPE" value="1" />
+    <option name="METHOD_NAME" value="" />
+    <option name="CLASS_NAME" value="" />
+    <option name="PACKAGE_NAME" value="org.briarproject.briar.android" />
+    <option name="INSTRUMENTATION_RUNNER_CLASS" value="" />
+    <option name="EXTRA_OPTIONS" value="-e notAnnotation androidx.test.filters.LargeTest" />
+    <option name="INCLUDE_GRADLE_EXTRA_OPTIONS" value="true" />
+    <option name="CLEAR_LOGCAT" value="false" />
+    <option name="SHOW_LOGCAT_AUTOMATICALLY" value="false" />
+    <option name="SKIP_NOOP_APK_INSTALLATIONS" value="true" />
+    <option name="FORCE_STOP_RUNNING_APP" value="true" />
+    <option name="TARGET_SELECTION_MODE" value="DEVICE_AND_SNAPSHOT_COMBO_BOX" />
+    <option name="DEBUGGER_TYPE" value="Auto" />
+    <Auto>
+      <option name="USE_JAVA_AWARE_DEBUGGER" value="false" />
+      <option name="SHOW_STATIC_VARS" value="true" />
+      <option name="WORKING_DIR" value="" />
+      <option name="TARGET_LOGGING_CHANNELS" value="lldb process:gdb-remote packets" />
+      <option name="SHOW_OPTIMIZED_WARNING" value="true" />
+    </Auto>
+    <Hybrid>
+      <option name="USE_JAVA_AWARE_DEBUGGER" value="false" />
+      <option name="SHOW_STATIC_VARS" value="true" />
+      <option name="WORKING_DIR" value="" />
+      <option name="TARGET_LOGGING_CHANNELS" value="lldb process:gdb-remote packets" />
+      <option name="SHOW_OPTIMIZED_WARNING" value="true" />
+    </Hybrid>
+    <Java />
+    <Native>
+      <option name="USE_JAVA_AWARE_DEBUGGER" value="false" />
+      <option name="SHOW_STATIC_VARS" value="true" />
+      <option name="WORKING_DIR" value="" />
+      <option name="TARGET_LOGGING_CHANNELS" value="lldb process:gdb-remote packets" />
+      <option name="SHOW_OPTIMIZED_WARNING" value="true" />
+    </Native>
+    <Profilers>
+      <option name="ADVANCED_PROFILING_ENABLED" value="false" />
+      <option name="STARTUP_PROFILING_ENABLED" value="false" />
+      <option name="STARTUP_CPU_PROFILING_ENABLED" value="false" />
+      <option name="STARTUP_CPU_PROFILING_CONFIGURATION_NAME" value="Sample Java Methods" />
+      <option name="STARTUP_NATIVE_MEMORY_PROFILING_ENABLED" value="false" />
+      <option name="NATIVE_MEMORY_SAMPLE_RATE_BYTES" value="2048" />
+    </Profilers>
+    <method v="2">
+      <option name="Android.Gradle.BeforeRunTask" enabled="true" />
+    </method>
+  </configuration>
+</component>

bramble-android/build.gradle

@@ -6,13 +6,17 @@ apply from: 'witness.gradle'
 
 android {
 	compileSdkVersion 30
-	buildToolsVersion '30.0.2'
+	buildToolsVersion '30.0.3'
+
+	packagingOptions {
+		doNotStrip '**/*.so'
+	}
 
 	defaultConfig {
 		minSdkVersion 16
-		targetSdkVersion 29
-		versionCode 10216
-		versionName "1.2.16"
+		targetSdkVersion 30
+		versionCode 10306
+		versionName "1.3.6"
 		consumerProguardFiles 'proguard-rules.txt'
 
 		testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
@@ -38,18 +42,18 @@ configurations {
 
 dependencies {
 	implementation project(path: ':bramble-core', configuration: 'default')
-	tor 'org.briarproject:tor-android:0.3.5.13@zip'
+	tor 'org.briarproject:tor-android:0.3.5.15'
 	tor 'org.briarproject:obfs4proxy-android:0.0.12-dev-40245c4a@zip'
 
-	annotationProcessor 'com.google.dagger:dagger-compiler:2.24'
+	annotationProcessor "com.google.dagger:dagger-compiler:$dagger_version"
 
 	compileOnly 'javax.annotation:jsr250-api:1.0'
 
 	testImplementation project(path: ':bramble-api', configuration: 'testOutput')
-	testImplementation 'junit:junit:4.12'
-	testImplementation "org.jmock:jmock:2.8.2"
-	testImplementation "org.jmock:jmock-junit4:2.8.2"
-	testImplementation "org.jmock:jmock-legacy:2.8.2"
+	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"
 }
 
 def torBinariesDir = 'src/main/res/raw'

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

@@ -59,8 +59,8 @@ import static org.briarproject.bramble.util.PrivacyUtils.scrubMacAddress;
 
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
-class AndroidBluetoothPlugin
-		extends BluetoothPlugin<BluetoothSocket, BluetoothServerSocket> {
+class AndroidBluetoothPlugin extends
+		AbstractBluetoothPlugin<BluetoothSocket, BluetoothServerSocket> {
 
 	private static final Logger LOG =
 			getLogger(AndroidBluetoothPlugin.class.getName());
@@ -75,6 +75,7 @@ class AndroidBluetoothPlugin
 
 	// Non-null if the plugin started successfully
 	private volatile BluetoothAdapter adapter = null;
+	private volatile boolean stopDiscoverAndConnect;
 
 	AndroidBluetoothPlugin(BluetoothConnectionLimiter connectionLimiter,
 			BluetoothConnectionFactory<BluetoothSocket> connectionFactory,
@@ -86,7 +87,7 @@ class AndroidBluetoothPlugin
 			Clock clock,
 			Backoff backoff,
 			PluginCallback callback,
-			int maxLatency,
+			long maxLatency,
 			int maxIdleTime) {
 		super(connectionLimiter, connectionFactory, ioExecutor,
 				wakefulIoExecutor, secureRandom, backoff, callback,
@@ -175,6 +176,11 @@ class AndroidBluetoothPlugin
 		} catch (IOException e) {
 			IoUtils.tryToClose(s, LOG, WARNING);
 			throw e;
+		} catch (NullPointerException e) {
+			// BluetoothSocket#connect() may throw an NPE under unknown
+			// circumstances
+			IoUtils.tryToClose(s, LOG, WARNING);
+			throw new IOException(e);
 		}
 	}
 
@@ -182,22 +188,40 @@ class AndroidBluetoothPlugin
 	@Nullable
 	DuplexTransportConnection discoverAndConnect(String uuid) {
 		if (adapter == null) return null;
-		for (String address : discoverDevices()) {
-			try {
-				if (LOG.isLoggable(INFO))
-					LOG.info("Connecting to " + scrubMacAddress(address));
-				return connectTo(address, uuid);
-			} catch (IOException e) {
-				if (LOG.isLoggable(INFO)) {
-					LOG.info("Could not connect to "
-							+ scrubMacAddress(address));
+		if (!discoverSemaphore.tryAcquire()) {
+			LOG.info("Discover already running");
+			return null;
+		}
+		try {
+			stopDiscoverAndConnect = false;
+			for (String address : discoverDevices()) {
+				if (stopDiscoverAndConnect) {
+					break;
+				}
+				try {
+					if (LOG.isLoggable(INFO))
+						LOG.info("Connecting to " + scrubMacAddress(address));
+					return connectTo(address, uuid);
+				} catch (IOException e) {
+					if (LOG.isLoggable(INFO)) {
+						LOG.info("Could not connect to "
+								+ scrubMacAddress(address));
+					}
 				}
 			}
+		} finally {
+			discoverSemaphore.release();
 		}
 		LOG.info("Could not connect to any devices");
 		return null;
 	}
 
+	@Override
+	public void stopDiscoverAndConnect() {
+		stopDiscoverAndConnect = true;
+		adapter.cancelDiscovery();
+	}
+
 	private Collection<String> discoverDevices() {
 		List<String> addresses = new ArrayList<>();
 		BlockingQueue<Intent> intents = new LinkedBlockingQueue<>();

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

@@ -47,7 +47,7 @@ public class AndroidBluetoothPluginFactory implements DuplexPluginFactory {
 	private final BackoffFactory backoffFactory;
 
 	@Inject
-	public AndroidBluetoothPluginFactory(@IoExecutor Executor ioExecutor,
+	AndroidBluetoothPluginFactory(@IoExecutor Executor ioExecutor,
 			@WakefulIoExecutor Executor wakefulIoExecutor,
 			AndroidExecutor androidExecutor,
 			AndroidWakeLockManager wakeLockManager,
@@ -75,7 +75,7 @@ public class AndroidBluetoothPluginFactory implements DuplexPluginFactory {
 	}
 
 	@Override
-	public int getMaxLatency() {
+	public long getMaxLatency() {
 		return MAX_LATENCY;
 	}
 

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

@@ -0,0 +1,44 @@
+package org.briarproject.bramble.plugin.file;
+
+import android.app.Application;
+import android.net.Uri;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.plugin.PluginCallback;
+import org.briarproject.bramble.api.properties.TransportProperties;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+
+import javax.annotation.concurrent.Immutable;
+
+import static org.briarproject.bramble.api.plugin.file.RemovableDriveConstants.PROP_URI;
+import static org.briarproject.bramble.util.StringUtils.isNullOrEmpty;
+
+@Immutable
+@NotNullByDefault
+class AndroidRemovableDrivePlugin extends RemovableDrivePlugin {
+
+	private final Application app;
+
+	AndroidRemovableDrivePlugin(Application app, PluginCallback callback,
+			long maxLatency) {
+		super(callback, maxLatency);
+		this.app = app;
+	}
+
+	@Override
+	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));
+	}
+
+	@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));
+	}
+}

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

@@ -0,0 +1,47 @@
+package org.briarproject.bramble.plugin.file;
+
+import android.app.Application;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.plugin.PluginCallback;
+import org.briarproject.bramble.api.plugin.TransportId;
+import org.briarproject.bramble.api.plugin.simplex.SimplexPlugin;
+import org.briarproject.bramble.api.plugin.simplex.SimplexPluginFactory;
+
+import javax.annotation.Nullable;
+import javax.annotation.concurrent.Immutable;
+import javax.inject.Inject;
+
+import static java.util.concurrent.TimeUnit.DAYS;
+import static org.briarproject.bramble.api.plugin.file.RemovableDriveConstants.ID;
+
+@Immutable
+@NotNullByDefault
+public class AndroidRemovableDrivePluginFactory implements
+		SimplexPluginFactory {
+
+	private static final long MAX_LATENCY = DAYS.toMillis(28);
+
+	private final Application app;
+
+	@Inject
+	AndroidRemovableDrivePluginFactory(Application app) {
+		this.app = app;
+	}
+
+	@Override
+	public TransportId getId() {
+		return ID;
+	}
+
+	@Override
+	public long getMaxLatency() {
+		return MAX_LATENCY;
+	}
+
+	@Nullable
+	@Override
+	public SimplexPlugin createPlugin(PluginCallback callback) {
+		return new AndroidRemovableDrivePlugin(app, callback, MAX_LATENCY);
+	}
+}

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

@@ -67,7 +67,7 @@ class AndroidLanTcpPlugin extends LanTcpPlugin {
 			Application app,
 			Backoff backoff,
 			PluginCallback callback,
-			int maxLatency,
+			long maxLatency,
 			int maxIdleTime,
 			int connectionTimeout) {
 		super(ioExecutor, wakefulIoExecutor, backoff, callback, maxLatency,

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

@@ -37,7 +37,7 @@ public class AndroidLanTcpPluginFactory implements DuplexPluginFactory {
 	private final Application app;
 
 	@Inject
-	public AndroidLanTcpPluginFactory(@IoExecutor Executor ioExecutor,
+	AndroidLanTcpPluginFactory(@IoExecutor Executor ioExecutor,
 			@WakefulIoExecutor Executor wakefulIoExecutor,
 			EventBus eventBus,
 			BackoffFactory backoffFactory,
@@ -55,7 +55,7 @@ public class AndroidLanTcpPluginFactory implements DuplexPluginFactory {
 	}
 
 	@Override
-	public int getMaxLatency() {
+	public long getMaxLatency() {
 		return MAX_LATENCY;
 	}
 

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

@@ -68,7 +68,7 @@ class AndroidTorPlugin extends TorPlugin {
 			TorRendezvousCrypto torRendezvousCrypto,
 			PluginCallback callback,
 			String architecture,
-			int maxLatency,
+			long maxLatency,
 			int maxIdleTime,
 			File torDirectory) {
 		super(ioExecutor, wakefulIoExecutor, networkManager, locationUtils,

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

@@ -58,7 +58,7 @@ public class AndroidTorPluginFactory implements DuplexPluginFactory {
 	private final File torDirectory;
 
 	@Inject
-	public AndroidTorPluginFactory(@IoExecutor Executor ioExecutor,
+	AndroidTorPluginFactory(@IoExecutor Executor ioExecutor,
 			@WakefulIoExecutor Executor wakefulIoExecutor,
 			Application app,
 			NetworkManager networkManager,
@@ -94,7 +94,7 @@ public class AndroidTorPluginFactory implements DuplexPluginFactory {
 	}
 
 	@Override
-	public int getMaxLatency() {
+	public long getMaxLatency() {
 		return MAX_LATENCY;
 	}
 

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

@@ -10,17 +10,20 @@ import org.briarproject.bramble.api.Pair;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 
 import java.io.File;
+import java.io.IOException;
 import java.lang.reflect.Field;
 import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.List;
+import java.util.Scanner;
 
 import javax.annotation.Nullable;
 
 import static android.content.Context.MODE_PRIVATE;
 import static android.os.Build.VERSION.SDK_INT;
+import static java.lang.Runtime.getRuntime;
 import static java.util.Arrays.asList;
 import static org.briarproject.bramble.api.nullsafety.NullSafety.requireNonNull;
 
@@ -114,12 +117,21 @@ public class AndroidUtils {
 
 	/**
 	 * Returns an array of supported content types for image attachments.
-	 * GIFs can't be compressed on API < 24 so they're not supported.
-	 * <p>
-	 * TODO: Remove this restriction when large message support is added
 	 */
 	public static String[] getSupportedImageContentTypes() {
-		if (SDK_INT < 24) return new String[] {"image/jpeg", "image/png"};
-		else return new String[] {"image/jpeg", "image/png", "image/gif"};
+		return new String[] {"image/jpeg", "image/png", "image/gif"};
+	}
+
+	@Nullable
+	public static String getSystemProperty(String propName) {
+		try {
+			Process p = getRuntime().exec("getprop " + propName);
+			Scanner s = new Scanner(p.getInputStream());
+			String line = s.nextLine();
+			s.close();
+			return line;
+		} catch (SecurityException | IOException e) {
+			return null;
+		}
 	}
 }

bramble-android/witness.gradle

@@ -1,42 +1,43 @@
 dependencyVerification {
     verify = [
-        'cglib:cglib:3.2.0:cglib-3.2.0.jar:adb13bab79712ad6bdf1bd59f2a3918018a8016e722e8a357065afb9e6690861',
-        'com.android.tools.analytics-library:protos:27.1.1:protos-27.1.1.jar:13f77e73762e58ab372d140b3a6be6903aea9775b62dd14fbc62d4cc7069c9a4',
-        'com.android.tools.analytics-library:shared:27.1.1:shared-27.1.1.jar:82930a52001410e97d809930b670f4de3002286975f046b9de5f6b777b06d366',
-        'com.android.tools.analytics-library:tracker:27.1.1:tracker-27.1.1.jar:31bc5a00be0055bac89c9b2f34751883e987cd89e3ac1783720645c164f591d9',
+        '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:shared:27.1.3:shared-27.1.3.jar:10d2a51d8f89ff4ac849888e5a9c60b10e879c30d78545ec1da4d3df7bd56ae4',
+        'com.android.tools.analytics-library:tracker:27.1.3:tracker-27.1.3.jar:589b355a2ba796cbc0a2b2295737de6661f078262e5f87cd6f540b8d011e5ebb',
         '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:4.1.1:apksig-4.1.1.jar:e0a69da9e5a03986d608b45bbf954ef0e6a0b3f58c1b8315bd169ec08b279e72',
-        'com.android.tools.build:apkzlib:4.1.1:apkzlib-4.1.1.jar:ba4b5e419b6be0130eae7f8301c3a551ad3976f487d2e0c6852ebb175ac41127',
-        'com.android.tools.build:builder-model:4.1.1:builder-model-4.1.1.jar:e95c99cc298ad67b8deb6ced99c51abc8f59afebedad044b1a10dde14646a4dd',
-        'com.android.tools.build:builder-test-api:4.1.1:builder-test-api-4.1.1.jar:464f596ab261c051c3847406748e843770dea123f6fa5fee8a9390644e709b7a',
-        'com.android.tools.build:builder:4.1.1:builder-4.1.1.jar:0f78d4759d2f7b57b95865522ec34596ba419b9982f3b25e3449213f9c98b80d',
-        'com.android.tools.build:gradle-api:4.1.1:gradle-api-4.1.1.jar:d42e6b539e4c1353ad3546e75ec8ce11a017b97481023e8ea18577eefe374358',
-        'com.android.tools.build:manifest-merger:27.1.1:manifest-merger-27.1.1.jar:7a45fa143687859bb2e5a961dcf6ee88094d3853de0cb543dc03dbcb0f4b554b',
-        'com.android.tools.ddms:ddmlib:27.1.1:ddmlib-27.1.1.jar:da6e4bd834b6a85dae8019039849d8bd96933347dfbf460df74913ddade6e40a',
-        'com.android.tools.external.com-intellij:intellij-core:27.1.1:intellij-core-27.1.1.jar:2591a7363c4443c59bf9f793730acafce9d6ec3076e2f46716edaf53a41b6fb6',
-        'com.android.tools.external.com-intellij:kotlin-compiler:27.1.1:kotlin-compiler-27.1.1.jar:5054ae770ba788f110303c65abd6b1fa28eccf52dee1274510e201b2b81885c8',
-        'com.android.tools.external.org-jetbrains:uast:27.1.1:uast-27.1.1.jar:54cd8f6886a9d2f5641659dd5c91f626629672cd48301f7f0bd6aad9bd448714',
-        'com.android.tools.layoutlib:layoutlib-api:27.1.1:layoutlib-api-27.1.1.jar:8a9a22e3b309521ea83b724e5a89cfdac6076f52d675c0e17d77b05527bc0f8c',
-        'com.android.tools.lint:lint-api:27.1.1:lint-api-27.1.1.jar:c1d8176094cb0478786070d40533efb578ebc53529a82f6ef5bee879bdca418b',
-        'com.android.tools.lint:lint-checks:27.1.1:lint-checks-27.1.1.jar:3899c91e00bd059b40c31a9ca00cd0f8303191947608735ae1b657323693fb61',
-        'com.android.tools.lint:lint-gradle-api:27.1.1:lint-gradle-api-27.1.1.jar:26aa89d38b9825cc73229daa82a68875801c8b8491f30497ce62aff1f206eb0d',
-        'com.android.tools.lint:lint-gradle:27.1.1:lint-gradle-27.1.1.jar:f7355823ead869f4d28184ba28b7a0c693b507519a2d3705bb9848a0f35b3756',
-        'com.android.tools.lint:lint-model:27.1.1:lint-model-27.1.1.jar:bc23c0c413bdfca59dac2cd56b870d8360d009e9ec0d365e71f774bcf127971d',
-        'com.android.tools.lint:lint:27.1.1:lint-27.1.1.jar:2f6038a5398a42bd591883c3f5e5894f4ec52ca1c3683bf94fa8553c1700af81',
-        'com.android.tools:annotations:27.1.1:annotations-27.1.1.jar:ff28c504d2acb9fd1a5ffbd97ae85cf59ee18c76927525aad250509bccf2cab1',
-        'com.android.tools:common:27.1.1:common-27.1.1.jar:63d9a2a9ad6d278db319f3749b9f50bdf5457ef7020074a1bebe124e714b535c',
-        'com.android.tools:dvlib:27.1.1:dvlib-27.1.1.jar:998a54201fc1cefee5f2399215e95c42b1f64f9e1d8f4452eb8255c68ba5440f',
-        'com.android.tools:repository:27.1.1:repository-27.1.1.jar:d25b74ccabf4d876903efb375e9af6fb380d8ae0445bb74bbdcc225c1e37fa1d',
-        'com.android.tools:sdk-common:27.1.1:sdk-common-27.1.1.jar:4473ae97d0ef7061ee1de61041d5aa97405ae08e44c09cf7bb278b42e4b97c7c',
-        'com.android.tools:sdklib:27.1.1:sdklib-27.1.1.jar:08e6b83961ac9724b3c1e3d0eff971f13be6701292c77914b8794480f3391250',
-        'com.android:signflinger:4.1.1:signflinger-4.1.1.jar:0c66825988873ec2d51057fa463f54a8f18fc7326ff4530b9da363b71e97ce60',
-        'com.android:zipflinger:4.1.1:zipflinger-4.1.1.jar:0a8c3e52ac13dd031236f9fb5ba4408b1d5dcd12325a05440b36da09d8881446',
+        'com.android.tools.build:apksig:4.1.3:apksig-4.1.3.jar:a851980c678ff7a6785388b9a9e8cc094788ce3c4a985ad2b19c2028fd3c631a',
+        'com.android.tools.build:apkzlib:4.1.3:apkzlib-4.1.3.jar:475903065e7e83a8c1ba78d267c97a54dc5a04d768b535093850423d7b11f2c8',
+        'com.android.tools.build:builder-model:4.1.3:builder-model-4.1.3.jar:2624a1436c3ab39dd91d3ecf9409a594b0f89ea5cab255f2e9ff11f5ee03d274',
+        'com.android.tools.build:builder-test-api:4.1.3:builder-test-api-4.1.3.jar:3d2af66726b06b53b8d6d497efcee39ff9f77eb2f8d2cce38b31502383a40d2c',
+        'com.android.tools.build:builder:4.1.3:builder-4.1.3.jar:a40426cd6d68f6a722ef4950058c075e4547025e8c2fd78e732ad89f15176f84',
+        'com.android.tools.build:gradle-api:4.1.3:gradle-api-4.1.3.jar:11b1fb9de658bdcf9290b1c1517060d0c4d93f2b27975934989ca4ac890bc077',
+        'com.android.tools.build:manifest-merger:27.1.3:manifest-merger-27.1.3.jar:ce8d4009b1f1584777a7ffa1da3b0551dc316bc8e08112e442c352af70f46f2d',
+        'com.android.tools.ddms:ddmlib:27.1.3:ddmlib-27.1.3.jar:8f76e8236d2b9eebf26378746dad025c4c7c056a02e133dae4ddef47b283c710',
+        '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:27.1.3:kotlin-compiler-27.1.3.jar:8d7a78d5efd213c5e467e42bd205582aad73ffc77ee5dc18eb1361c9af72f125',
+        'com.android.tools.external.org-jetbrains:uast:27.1.3:uast-27.1.3.jar:aea53944a1ac6a05f12297b55290e8cbecfe54c4166260cfba4405823bfe1c78',
+        'com.android.tools.layoutlib:layoutlib-api:27.1.3:layoutlib-api-27.1.3.jar:23875ce0a8429f33a4e86cc358f658faa0ba9c576f5f05760e544b453d67d04b',
+        'com.android.tools.lint:lint-api:27.1.3:lint-api-27.1.3.jar:97666be32bcadacd944416ea334a9575ef8f4ad0c8f333151491ff4a7df43e1c',
+        'com.android.tools.lint:lint-checks:27.1.3:lint-checks-27.1.3.jar:b2d71ae84a31490fe9ff26c706163fe245b2aea98e3eb747214c1085df444708',
+        'com.android.tools.lint:lint-gradle-api:27.1.3:lint-gradle-api-27.1.3.jar:e54131c287a2954e6ed78a3351e5e10e35a1da2f09ac443bf44b705c71b63a4d',
+        'com.android.tools.lint:lint-gradle:27.1.3:lint-gradle-27.1.3.jar:6a79e48943649d63665db7b17dbaff7af93e94ab9b15072f1a4d90486294ee9f',
+        'com.android.tools.lint:lint-model:27.1.3:lint-model-27.1.3.jar:acb9e792db7000e38e3c3ca21a9b14f2de6549d7a3fc92a97ffba3d06345e5bf',
+        'com.android.tools.lint:lint:27.1.3:lint-27.1.3.jar:5a2e69d0901a3a476a5b2d5001de755868113145f5f6aa557750cfad5389a44b',
+        'com.android.tools:annotations:27.1.3:annotations-27.1.3.jar:904dd771883496d5dfc86619ab2555968ea4e8a29d7a5f4f7cae6fbf5429f8f5',
+        'com.android.tools:common:27.1.3:common-27.1.3.jar:17ab4728e3ea50f047dd5937f0faf35f2c5416962ed74891057087ddc328bf96',
+        'com.android.tools:dvlib:27.1.3:dvlib-27.1.3.jar:cead1c0c356cbe43e6855b0330fe09ef4bec2c72e22bdb4c6e7cf7e6b1dfbc37',
+        'com.android.tools:repository:27.1.3:repository-27.1.3.jar:99de1a178855b56b8cd91a56296f1e0a9399c445e6acc51f1d2927947cc472cb',
+        'com.android.tools:sdk-common:27.1.3:sdk-common-27.1.3.jar:b591e2aa0f1be600795f5c9e2bf81cba9b052bee452fc86c3362b5dd9e427a14',
+        'com.android.tools:sdklib:27.1.3:sdklib-27.1.3.jar:ad6c08a45fe2904d05656bdddf9f623fa5c1d16bbd7b8d6a270a0734136ae02e',
+        'com.android:signflinger:4.1.3:signflinger-4.1.3.jar:f3103b55ccdc8dd9ee2517eb26af93b904d41303726594372d0df59d51156e5c',
+        'com.android:zipflinger:4.1.3:zipflinger-4.1.3.jar:48569896c0497268308a8014c66eb0f2bace2b9e2fc9390f3012823fb86387d5',
+        '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.dagger:dagger-compiler:2.24:dagger-compiler-2.24.jar:3c5afb955fb188da485cb2c048eff37dce0e1530b9780a0f2f7187d16d1ccc1f',
-        'com.google.dagger:dagger-producers:2.24:dagger-producers-2.24.jar:f10f45b95191954d5d6b043fca9e62fb621d21bf70634b8f8476c7988b504c3a',
-        'com.google.dagger:dagger-spi:2.24:dagger-spi-2.24.jar:c038445d14dbcb4054e61bf49e05009edf26fce4fdc7ec1a9db544784f68e718',
-        'com.google.dagger:dagger:2.24:dagger-2.24.jar:550a6e46a6dfcdf1d764887b6090cea94f783327e50e5c73754f18facfc70b64',
+        '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:javac-shaded:9-dev-r4023-3:javac-shaded-9-dev-r4023-3.jar:65bfccf60986c47fbc17c9ebab0be626afc41741e0a6ec7109e0768817a36f30',
@@ -50,7 +51,7 @@ dependencyVerification {
         'com.google.jimfs:jimfs:1.1:jimfs-1.1.jar:c4828e28d7c0a930af9387510b3bada7daa5c04d7c25a75c7b8b081f1c257ddd',
         'com.google.protobuf:protobuf-java:3.10.0:protobuf-java-3.10.0.jar:161d7d61a8cb3970891c299578702fd079646e032329d6c2cabf998d191437c9',
         'com.googlecode.json-simple:json-simple:1.1:json-simple-1.1.jar:2d9484f4c649f708f47f9a479465fc729770ee65617dca3011836602264f6439',
-        'com.squareup:javapoet:1.11.1:javapoet-1.11.1.jar:9cbf2107be499ec6e95afd36b58e3ca122a24166cdd375732e51267d64058e90',
+        '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',
@@ -62,21 +63,21 @@ dependencyVerification {
         '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',
-        'junit:junit:4.12:junit-4.12.jar:59721f0805e223d84b90677887d9ff567dc534d7c502ca903c0c2b17f05c116a',
+        'junit:junit:4.13.2:junit-4.13.2.jar:8e495b634469d64fb8acfa3495a065cbacc8a0fff55ce1e31007be4c16dc57d3',
+        'net.bytebuddy:byte-buddy:1.9.12:byte-buddy-1.9.12.jar:3688c3d434bebc3edc5516296a2ed0f47b65e451071b4afecad84f902f0efc11',
+        '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.ant:ant-launcher:1.9.4:ant-launcher-1.9.4.jar:7bccea20b41801ca17bcbc909a78c835d0f443f12d639c77bd6ae3d05861608d',
-        'org.apache.ant:ant:1.9.4:ant-1.9.4.jar:649ae0730251de07b8913f49286d46bba7b92d47c5f332610aa426c4f02161d8',
+        '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.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.beanshell:bsh:1.3.0:bsh-1.3.0.jar:9b04edc75d19db54f1b4e8b5355e9364384c6cf71eb0a1b9724c159d779879f8',
         '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:tor-android:0.3.5.13:tor-android-0.3.5.13.zip:e0978db136731dae07774b722970cdae1e462fb5adc82845dd80a7e2d87f356c',
+        'org.briarproject:tor-android:0.3.5.15:tor-android-0.3.5.15.jar:560c5070166300b396cb2f28d82d9f639ee1fb5479096a3cef67da56d39937ad',
         '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',
@@ -85,26 +86,31 @@ dependencyVerification {
         'org.codehaus.mojo:animal-sniffer-annotations:1.18:animal-sniffer-annotations-1.18.jar:47f05852b48ee9baefef80fa3d8cea60efa4753c0013121dd7fe5eef2e5c729d',
         'org.glassfish.jaxb:jaxb-runtime:2.3.1:jaxb-runtime-2.3.1.jar:45fecfa5c8217ce1f3652ab95179790ec8cc0dec0384bca51cbeb94a293d9f2f',
         'org.glassfish.jaxb:txw2:2.3.1:txw2-2.3.1.jar:34975dde1c6920f1a39791142235689bc3cd357e24d05edd8ff93b885bd68d60',
-        'org.hamcrest:hamcrest-core:1.3:hamcrest-core-1.3.jar:66fdef91e9739348df7a096aa384a5685f4e875584cce89386a7a47251c4d8e9',
-        'org.hamcrest:hamcrest-library:1.3:hamcrest-library-1.3.jar:711d64522f9ec410983bd310934296da134be4254a125080a0416ec178dfad1c',
+        '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.jetbrains.kotlin:kotlin-stdlib-common:1.3.72:kotlin-stdlib-common-1.3.72.jar:5e7d1552863e480c1628b1cc39ce230ef829f5b7230106215a05acda5172203a',
+        '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-jdk8:1.3.72:kotlin-stdlib-jdk8-1.3.72.jar:133da70cfc07b56094282eac5c59bccd59f167ee2ead22e5282876d8bc10bf95',
         'org.jetbrains.kotlin:kotlin-stdlib:1.3.72:kotlin-stdlib-1.3.72.jar:3856a7349ebacd6d1be6802b2fed9c4dc2c5a564ea92b6b945ac988243d4b16b',
+        'org.jetbrains.kotlin:kotlin-stdlib:1.4.20:kotlin-stdlib-1.4.20.jar:b8ab1da5cdc89cb084d41e1f28f20a42bd431538642a5741c52bbfae3fa3e656',
+        '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-junit4:2.8.2:jmock-junit4-2.8.2.jar:f7ee4df4f7bd7b7f1cafad3b99eb74d579f109d5992ff625347352edb55e674c',
-        'org.jmock:jmock-legacy:2.8.2:jmock-legacy-2.8.2.jar:f2b985a5c08a9edb7f37612330c058809da3f6a6d63ce792426ebf8ff0d6d31b',
-        'org.jmock:jmock-testjar:2.8.2:jmock-testjar-2.8.2.jar:8900860f72c474e027cf97fe78dcbf154a1aa7fc62b6845c5fb4e4f3c7bc8760',
-        'org.jmock:jmock:2.8.2:jmock-2.8.2.jar:6c73cb4a2e6dbfb61fd99c9a768539c170ab6568e57846bd60dbf19596b65b16',
+        '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.objenesis:objenesis:2.1:objenesis-2.1.jar:c74330cc6b806c804fd37e74487b4fe5d7c2750c5e15fbc6efa13bdee1bdef80',
+        'org.objenesis:objenesis:3.0.1:objenesis-3.0.1.jar:7a8ff780b9ff48415d7c705f60030b0acaa616e7f823c98eede3b63508d4e984',
         '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:5.0.4:asm-5.0.4.jar:896618ed8ae62702521a78bc7be42b7c491a08e6920a15f89a3ecdec31e9a220',
         'org.ow2.asm:asm:7.0:asm-7.0.jar:b88ef66468b3c978ad0c97fd6e90979e56155b4ac69089ba7a44e9aa7ffe9acf',
+        'org.ow2.asm:asm:7.1:asm-7.1.jar:4ab2fa2b6d2cc9ccb1eaa05ea329c407b47b13ed2915f62f8c4b8cc96258d4de',
     ]
 }

bramble-api/build.gradle

@@ -7,13 +7,13 @@ apply plugin: 'witness'
 apply from: 'witness.gradle'
 
 dependencies {
-	implementation "com.google.dagger:dagger:2.24"
+	implementation "com.google.dagger:dagger:$dagger_version"
 	implementation 'com.google.code.findbugs:jsr305:3.0.2'
 
-	testImplementation 'junit:junit:4.12'
-	testImplementation "org.jmock:jmock:2.8.2"
-	testImplementation "org.jmock:jmock-junit4:2.8.2"
-	testImplementation "org.jmock:jmock-legacy:2.8.2"
+	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/Consumer.java

@@ -0,0 +1,9 @@
+package org.briarproject.bramble.api;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+@NotNullByDefault
+public interface Consumer<T> {
+
+	void accept(T t);
+}

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

@@ -9,4 +9,9 @@ public interface FeatureFlags {
 
 	boolean shouldEnableProfilePictures();
 
+	boolean shouldEnableDisappearingMessages();
+
+	boolean shouldEnableConnectViaBluetooth();
+
+	boolean shouldEnableTransferData();
 }

bramble-api/src/main/java/org/briarproject/bramble/api/cleanup/CleanupHook.java

@@ -0,0 +1,29 @@
+package org.briarproject.bramble.api.cleanup;
+
+import org.briarproject.bramble.api.db.DatabaseComponent;
+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.GroupId;
+import org.briarproject.bramble.api.sync.MessageId;
+
+import java.util.Collection;
+
+/**
+ * An interface for registering a hook with the {@link CleanupManager}
+ * that will be called when a message's cleanup deadline is reached.
+ */
+@NotNullByDefault
+public interface CleanupHook {
+
+	/**
+	 * Called when the cleanup deadlines of one or more messages are reached.
+	 * <p>
+	 * The callee is not required to delete the messages, but the hook won't be
+	 * called again for these messages unless another cleanup timer is set (see
+	 * {@link DatabaseComponent#setCleanupTimerDuration(Transaction, MessageId, long)}
+	 * and {@link DatabaseComponent#startCleanupTimer(Transaction, MessageId)}).
+	 */
+	void deleteMessages(Transaction txn, GroupId g,
+			Collection<MessageId> messageIds) throws DbException;
+}

bramble-api/src/main/java/org/briarproject/bramble/api/cleanup/CleanupManager.java

@@ -0,0 +1,42 @@
+package org.briarproject.bramble.api.cleanup;
+
+import org.briarproject.bramble.api.cleanup.event.CleanupTimerStartedEvent;
+import org.briarproject.bramble.api.crypto.SecretKey;
+import org.briarproject.bramble.api.db.DatabaseComponent;
+import org.briarproject.bramble.api.db.Transaction;
+import org.briarproject.bramble.api.lifecycle.LifecycleManager;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.sync.ClientId;
+import org.briarproject.bramble.api.sync.MessageId;
+
+/**
+ * The CleanupManager is responsible for tracking the cleanup deadlines of
+ * messages and passing them to their respective
+ * {@link CleanupHook CleanupHooks} when the deadlines are reached.
+ * <p>
+ * The CleanupManager responds to
+ * {@link CleanupTimerStartedEvent CleanupTimerStartedEvents} broadcast by the
+ * {@link DatabaseComponent}.
+ * <p>
+ * See {@link DatabaseComponent#setCleanupTimerDuration(Transaction, MessageId, long)},
+ * {@link DatabaseComponent#startCleanupTimer(Transaction, MessageId)},
+ * {@link DatabaseComponent#stopCleanupTimer(Transaction, MessageId)}.
+ */
+@NotNullByDefault
+public interface CleanupManager {
+
+	/**
+	 * When scheduling a cleanup task we overshoot the deadline by this many
+	 * milliseconds to reduce the number of tasks that need to be scheduled
+	 * when messages have cleanup deadlines that are close together.
+	 */
+	long BATCH_DELAY_MS = 1000;
+
+	/**
+	 * Registers a hook to be called when messages are due for cleanup.
+	 * This method should be called before
+	 * {@link LifecycleManager#startServices(SecretKey)}.
+	 */
+	void registerCleanupHook(ClientId c, int majorVersion,
+			CleanupHook hook);
+}

bramble-api/src/main/java/org/briarproject/bramble/api/cleanup/event/CleanupTimerStartedEvent.java

@@ -0,0 +1,32 @@
+package org.briarproject.bramble.api.cleanup.event;
+
+import org.briarproject.bramble.api.event.Event;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.sync.MessageId;
+
+import javax.annotation.concurrent.Immutable;
+
+/**
+ * An event that is broadcast when a message's cleanup timer is started.
+ */
+@Immutable
+@NotNullByDefault
+public class CleanupTimerStartedEvent extends Event {
+
+	private final MessageId messageId;
+	private final long cleanupDeadline;
+
+	public CleanupTimerStartedEvent(MessageId messageId,
+			long cleanupDeadline) {
+		this.messageId = messageId;
+		this.cleanupDeadline = cleanupDeadline;
+	}
+
+	public MessageId getMessageId() {
+		return messageId;
+	}
+
+	public long getCleanupDeadline() {
+		return cleanupDeadline;
+	}
+}

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

@@ -32,28 +32,31 @@ public abstract class BdfIncomingMessageHook implements IncomingMessageHook {
 
 	/**
 	 * Called once for each incoming message that passes validation.
+	 * <p>
+	 * If an unexpected exception occurs while handling data that is assumed
+	 * to be valid (e.g. locally created metadata), it may be sensible to
+	 * rethrow the unexpected exception as a DbException so that delivery is
+	 * attempted again at next startup. This will allow delivery to succeed if
+	 * the unexpected exception was caused by a bug that has subsequently been
+	 * fixed.
 	 *
 	 * @param txn A read-write transaction
-	 * @return Whether or not this message should be shared
-	 * @throws DbException Should only be used for real database errors.
-	 * If this is thrown, delivery will be attempted again at next startup,
-	 * whereas if a FormatException is thrown, the message will be permanently
-	 * invalidated.
-	 * @throws FormatException Use this for any non-database error
-	 * that occurs while handling remotely created data.
-	 * This includes errors that occur while handling locally created data
-	 * in a context controlled by remotely created data
-	 * (for example, parsing the metadata of a dependency
-	 * of an incoming message).
-	 * Never rethrow DbException as FormatException!
+	 * @throws DbException if a database error occurs while delivering the
+	 * message. Delivery will be attempted again at next startup. Throwing
+	 * this exception has the same effect as returning
+	 * {@link DeliveryAction#DEFER}.
+	 * @throws FormatException if the message is invalid in the context of its
+	 * dependencies. The message and any dependents will be marked as invalid
+	 * and deleted along with their metadata. Throwing this exception has the
+	 * same effect as returning {@link DeliveryAction#REJECT}.
 	 */
-	protected abstract boolean incomingMessage(Transaction txn, Message m,
-			BdfList body, BdfDictionary meta) throws DbException,
-			FormatException;
+	protected abstract DeliveryAction incomingMessage(Transaction txn,
+			Message m, BdfList body, BdfDictionary meta)
+			throws DbException, FormatException;
 
 	@Override
-	public boolean incomingMessage(Transaction txn, Message m, Metadata meta)
-			throws DbException, InvalidMessageException {
+	public DeliveryAction incomingMessage(Transaction txn, Message m,
+			Metadata meta) throws DbException, InvalidMessageException {
 		try {
 			BdfList body = clientHelper.toList(m);
 			BdfDictionary metaDictionary = metadataParser.parse(meta);

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

@@ -1,6 +1,7 @@
 package org.briarproject.bramble.api.client;
 
 import org.briarproject.bramble.api.FormatException;
+import org.briarproject.bramble.api.contact.ContactId;
 import org.briarproject.bramble.api.crypto.PrivateKey;
 import org.briarproject.bramble.api.crypto.PublicKey;
 import org.briarproject.bramble.api.data.BdfDictionary;
@@ -16,6 +17,7 @@ import org.briarproject.bramble.api.sync.Message;
 import org.briarproject.bramble.api.sync.MessageId;
 
 import java.security.GeneralSecurityException;
+import java.util.Collection;
 import java.util.Map;
 
 @NotNullByDefault
@@ -50,9 +52,11 @@ public interface ClientHelper {
 	BdfDictionary getGroupMetadataAsDictionary(Transaction txn, GroupId g)
 			throws DbException, FormatException;
 
+	Collection<MessageId> getMessageIds(Transaction txn, GroupId g,
+			BdfDictionary query) throws DbException, FormatException;
+
 	BdfDictionary getMessageMetadataAsDictionary(MessageId m)
-			throws DbException,
-			FormatException;
+			throws DbException, FormatException;
 
 	BdfDictionary getMessageMetadataAsDictionary(Transaction txn, MessageId m)
 			throws DbException, FormatException;
@@ -119,4 +123,17 @@ public interface ClientHelper {
 	Map<TransportId, TransportProperties> parseAndValidateTransportPropertiesMap(
 			BdfDictionary properties) throws FormatException;
 
+	/**
+	 * Retrieves the contact ID from the group metadata of the given contact
+	 * group.
+	 */
+	ContactId getContactId(Transaction txn, GroupId contactGroupId)
+			throws DbException, FormatException;
+
+	/**
+	 * Stores the given contact ID in the group metadata of the given contact
+	 * group.
+	 */
+	void setContactId(Transaction txn, GroupId contactGroupId, ContactId c)
+			throws DbException;
 }

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

@@ -0,0 +1,9 @@
+package org.briarproject.bramble.api.client;
+
+public interface ContactGroupConstants {
+
+	/**
+	 * Group metadata key for associating a contact ID with a contact group.
+	 */
+	String GROUP_KEY_CONTACT_ID = "contactId";
+}

bramble-api/src/main/java/org/briarproject/bramble/api/contact/event/ContactAliasChangedEvent.java

@@ -0,0 +1,35 @@
+package org.briarproject.bramble.api.contact.event;
+
+import org.briarproject.bramble.api.contact.ContactId;
+import org.briarproject.bramble.api.event.Event;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import javax.annotation.Nullable;
+import javax.annotation.concurrent.Immutable;
+
+/**
+ * An event that is broadcast when the alias for a contact changed.
+ */
+@Immutable
+@NotNullByDefault
+public class ContactAliasChangedEvent extends Event {
+
+	private final ContactId contactId;
+	@Nullable
+	private final String alias;
+
+	public ContactAliasChangedEvent(ContactId contactId,
+			@Nullable String alias) {
+		this.contactId = contactId;
+		this.alias = alias;
+	}
+
+	public ContactId getContactId() {
+		return contactId;
+	}
+
+	@Nullable
+	public String getAlias() {
+		return alias;
+	}
+}

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

@@ -1,23 +1,19 @@
 package org.briarproject.bramble.api.crypto;
 
+import org.briarproject.bramble.api.Bytes;
+
 /**
  * A secret key used for encryption and/or authentication.
  */
-public class SecretKey {
+public class SecretKey extends Bytes {
 
 	/**
 	 * The length of a secret key in bytes.
 	 */
 	public static final int LENGTH = 32;
 
-	private final byte[] key;
-
 	public SecretKey(byte[] key) {
+		super(key);
 		if (key.length != LENGTH) throw new IllegalArgumentException();
-		this.key = key;
-	}
-
-	public byte[] getBytes() {
-		return key;
 	}
 }

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

@@ -41,6 +41,18 @@ import javax.annotation.Nullable;
 @NotNullByDefault
 public interface DatabaseComponent extends TransactionManager {
 
+	/**
+	 * Return value for {@link #getNextCleanupDeadline(Transaction)} if
+	 * no messages are scheduled to be deleted.
+	 */
+	long NO_CLEANUP_DEADLINE = -1;
+
+	/**
+	 * Return value for {@link #startCleanupTimer(Transaction, MessageId)}
+	 * if the cleanup timer was not started.
+	 */
+	long TIMER_NOT_STARTED = -1;
+
 	/**
 	 * Opens the database and returns true if the database already existed.
 	 *
@@ -89,7 +101,7 @@ public interface DatabaseComponent extends TransactionManager {
 	/**
 	 * Stores a transport.
 	 */
-	void addTransport(Transaction txn, TransportId t, int maxLatency)
+	void addTransport(Transaction txn, TransportId t, long maxLatency)
 			throws DbException;
 
 	/**
@@ -106,6 +118,18 @@ public interface DatabaseComponent extends TransactionManager {
 	KeySetId addTransportKeys(Transaction txn, PendingContactId p,
 			TransportKeys k) throws DbException;
 
+	/**
+	 * Returns true if there are any acks or messages to send to the given
+	 * contact over a transport with the given maximum latency.
+	 * <p/>
+	 * Read-only.
+	 *
+	 * @param eager True if messages that are not yet due for retransmission
+	 * should be included
+	 */
+	boolean containsAnythingToSend(Transaction txn, ContactId c,
+			long maxLatency, boolean eager) throws DbException;
+
 	/**
 	 * Returns true if the database contains the given contact for the given
 	 * local pseudonym.
@@ -138,6 +162,16 @@ public interface DatabaseComponent extends TransactionManager {
 	boolean containsPendingContact(Transaction txn, PendingContactId p)
 			throws DbException;
 
+	/**
+	 * Returns true if the database contains keys for communicating with the
+	 * given contact over the given transport. Handshake mode and rotation mode
+	 * keys are included, whether activated or not.
+	 * <p/>
+	 * Read-only.
+	 */
+	boolean containsTransportKeys(Transaction txn, ContactId c, TransportId t)
+			throws DbException;
+
 	/**
 	 * Deletes the message with the given ID. Unlike
 	 * {@link #removeMessage(Transaction, MessageId)}, the message ID,
@@ -166,7 +200,19 @@ public interface DatabaseComponent extends TransactionManager {
 	 */
 	@Nullable
 	Collection<Message> generateBatch(Transaction txn, ContactId c,
-			int maxLength, int maxLatency) throws DbException;
+			int maxLength, 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
@@ -175,7 +221,7 @@ public interface DatabaseComponent extends TransactionManager {
 	 */
 	@Nullable
 	Offer generateOffer(Transaction txn, ContactId c, int maxMessages,
-			int maxLatency) throws DbException;
+			long maxLatency) throws DbException;
 
 	/**
 	 * Returns a request for the given contact, or null if there are no
@@ -194,7 +240,7 @@ public interface DatabaseComponent extends TransactionManager {
 	 */
 	@Nullable
 	Collection<Message> generateRequestedBatch(Transaction txn, ContactId c,
-			int maxLength, int maxLatency) throws DbException;
+			int maxLength, long maxLatency) throws DbException;
 
 	/**
 	 * Returns the contact with the given ID.
@@ -288,6 +334,16 @@ public interface DatabaseComponent extends TransactionManager {
 	Collection<MessageId> getMessageIds(Transaction txn, GroupId g)
 			throws DbException;
 
+	/**
+	 * Returns the IDs of any delivered messages in the given group with
+	 * metadata that matches all entries in the given query. If the query is
+	 * empty, the IDs of all delivered messages are returned.
+	 * <p/>
+	 * Read-only.
+	 */
+	Collection<MessageId> getMessageIds(Transaction txn, GroupId g,
+			Metadata query) throws DbException;
+
 	/**
 	 * Returns the IDs of any messages that need to be validated.
 	 * <p/>
@@ -314,6 +370,15 @@ public interface DatabaseComponent extends TransactionManager {
 	Collection<MessageId> getMessagesToShare(Transaction txn)
 			throws DbException;
 
+	/**
+	 * Returns the IDs of any messages of any messages that are due for
+	 * deletion, along with their group IDs.
+	 * <p/>
+	 * Read-only.
+	 */
+	Map<GroupId, Collection<MessageId>> getMessagesToDelete(Transaction txn)
+			throws DbException;
+
 	/**
 	 * Returns the metadata for all delivered messages in the given group.
 	 * <p/>
@@ -395,6 +460,36 @@ public interface DatabaseComponent extends TransactionManager {
 	MessageStatus getMessageStatus(Transaction txn, ContactId c, MessageId m)
 			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
+	 * messages that have already been sent and are not yet due for
+	 * retransmission.
+	 * <p/>
+	 * Read-only.
+	 */
+	Map<MessageId, Integer> getUnackedMessagesToSend(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
+	 * that have already been sent and are not yet due for retransmission.
+	 * <p/>
+	 * Read-only.
+	 */
+	long getUnackedMessageBytesToSend(Transaction txn, ContactId c)
+			throws DbException;
+
+	/**
+	 * Returns the next time (in milliseconds since the Unix epoch) when a
+	 * message is due to be deleted, or {@link #NO_CLEANUP_DEADLINE}
+	 * if no messages are scheduled to be deleted.
+	 * <p/>
+	 * Read-only.
+	 */
+	long getNextCleanupDeadline(Transaction txn) throws DbException;
+
 	/*
 	 * Returns the next time (in milliseconds since the Unix epoch) when a
 	 * message is due to be sent to the given contact. The returned value may
@@ -443,6 +538,16 @@ public interface DatabaseComponent extends TransactionManager {
 	Collection<TransportKeySet> getTransportKeys(Transaction txn, TransportId t)
 			throws DbException;
 
+	/**
+	 * Returns the contact IDs and transport IDs for which the DB contains
+	 * at least one set of transport keys. Handshake mode and rotation mode
+	 * keys are included, whether activated or not.
+	 * <p/>
+	 * Read-only.
+	 */
+	Map<ContactId, Collection<TransportId>> getTransportsWithKeys(
+			Transaction txn) throws DbException;
+
 	/**
 	 * Increments the outgoing stream counter for the given transport keys.
 	 */
@@ -535,6 +640,13 @@ public interface DatabaseComponent extends TransactionManager {
 	void removeTransportKeys(Transaction txn, TransportId t, KeySetId k)
 			throws DbException;
 
+	/**
+	 * Sets the cleanup timer duration for the given message. This does not
+	 * start the message's cleanup timer.
+	 */
+	void setCleanupTimerDuration(Transaction txn, MessageId m, long duration)
+			throws DbException;
+
 	/**
 	 * Marks the given contact as verified.
 	 */
@@ -557,6 +669,12 @@ public interface DatabaseComponent extends TransactionManager {
 	 */
 	void setMessagePermanent(Transaction txn, MessageId m) throws DbException;
 
+	/**
+	 * Marks the given message as not shared. This method is only meant for
+	 * testing.
+	 */
+	void setMessageNotShared(Transaction txn, MessageId m) throws DbException;
+
 	/**
 	 * Marks the given message as shared.
 	 */
@@ -599,6 +717,22 @@ public interface DatabaseComponent extends TransactionManager {
 	void setTransportKeysActive(Transaction txn, TransportId t, KeySetId k)
 			throws DbException;
 
+	/**
+	 * Starts the cleanup timer for the given message, if a timer duration
+	 * has been set and the timer has not already been started.
+	 *
+	 * @return The cleanup deadline, or {@link #TIMER_NOT_STARTED} if no
+	 * timer duration has been set for this message or its timer has already
+	 * been started.
+	 */
+	long startCleanupTimer(Transaction txn, MessageId m) throws DbException;
+
+	/**
+	 * Stops the cleanup timer for the given message, if the timer has been
+	 * started.
+	 */
+	void stopCleanupTimer(Transaction txn, MessageId m) throws DbException;
+
 	/**
 	 * Stores the given transport keys, deleting any keys they have replaced.
 	 */

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

@@ -57,6 +57,7 @@ public class Author implements Nameable {
 	/**
 	 * Returns the author's name.
 	 */
+	@Override
 	public String getName() {
 		return name;
 	}

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

@@ -26,11 +26,6 @@ public interface IdentityManager {
 	 */
 	void registerIdentity(Identity i);
 
-	/**
-	 * Returns the cached local identity or loads it from the database.
-	 */
-	Identity getIdentity(Transaction txn) throws DbException;
-
 	/**
 	 * Returns the cached local identity or loads it from the database.
 	 */

bramble-api/src/main/java/org/briarproject/bramble/api/keyagreement/event/KeyAgreementStartedEvent.java

@@ -3,7 +3,7 @@ package org.briarproject.bramble.api.keyagreement.event;
 import org.briarproject.bramble.api.event.Event;
 
 /**
- * An event that is broadcast when a BQP protocol completes.
+ * An event that is broadcast when a BQP protocol begins.
  */
 public class KeyAgreementStartedEvent extends Event {
 }

bramble-api/src/main/java/org/briarproject/bramble/api/lifecycle/LifecycleManager.java

@@ -5,6 +5,7 @@ import org.briarproject.bramble.api.db.DatabaseComponent;
 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.system.Clock;
 import org.briarproject.bramble.api.system.Wakeful;
 
 import java.util.concurrent.ExecutorService;
@@ -22,6 +23,7 @@ public interface LifecycleManager {
 	 */
 	enum StartResult {
 		ALREADY_RUNNING,
+		CLOCK_ERROR,
 		DB_ERROR,
 		DATA_TOO_OLD_ERROR,
 		DATA_TOO_NEW_ERROR,
@@ -65,6 +67,10 @@ public interface LifecycleManager {
 	/**
 	 * Opens the {@link DatabaseComponent} using the given key and starts any
 	 * registered {@link Service Services}.
+	 *
+	 * @return {@link StartResult#CLOCK_ERROR} if the system clock is earlier
+	 * than {@link Clock#MIN_REASONABLE_TIME_MS} or later than
+	 * {@link Clock#MAX_REASONABLE_TIME_MS}.
 	 */
 	@Wakeful
 	StartResult startServices(SecretKey dbKey);

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

@@ -61,7 +61,7 @@ public interface Plugin {
 	/**
 	 * Returns the transport's maximum latency in milliseconds.
 	 */
-	int getMaxLatency();
+	long getMaxLatency();
 
 	/**
 	 * Returns the transport's maximum idle time in milliseconds.

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

@@ -0,0 +1,25 @@
+package org.briarproject.bramble.api.plugin;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import javax.annotation.Nullable;
+
+@NotNullByDefault
+public interface PluginFactory<P extends Plugin> {
+
+	/**
+	 * Returns the plugin's transport identifier.
+	 */
+	TransportId getId();
+
+	/**
+	 * Returns the maximum latency of the transport in milliseconds.
+	 */
+	long getMaxLatency();
+
+	/**
+	 * Creates and returns a plugin, or null if no plugin can be created.
+	 */
+	@Nullable
+	P createPlugin(PluginCallback callback);
+}

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

@@ -15,13 +15,18 @@ public interface TransportConnectionWriter {
 	/**
 	 * Returns the maximum latency of the transport in milliseconds.
 	 */
-	int getMaxLatency();
+	long getMaxLatency();
 
 	/**
 	 * Returns the maximum idle time of the transport in milliseconds.
 	 */
 	int getMaxIdleTime();
 
+	/**
+	 * Returns true if the transport is lossy and cheap.
+	 */
+	boolean isLossyAndCheap();
+
 	/**
 	 * Returns an output stream for writing to the transport connection.
 	 */

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

@@ -70,7 +70,7 @@ public abstract class AbstractDuplexTransportConnection
 	private class Writer implements TransportConnectionWriter {
 
 		@Override
-		public int getMaxLatency() {
+		public long getMaxLatency() {
 			return plugin.getMaxLatency();
 		}
 
@@ -79,6 +79,11 @@ public abstract class AbstractDuplexTransportConnection
 			return plugin.getMaxIdleTime();
 		}
 
+		@Override
+		public boolean isLossyAndCheap() {
+			return false;
+		}
+
 		@Override
 		public OutputStream getOutputStream() throws IOException {
 			return AbstractDuplexTransportConnection.this.getOutputStream();

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

@@ -1,30 +1,11 @@
 package org.briarproject.bramble.api.plugin.duplex;
 
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.plugin.PluginCallback;
-import org.briarproject.bramble.api.plugin.TransportId;
-
-import javax.annotation.Nullable;
+import org.briarproject.bramble.api.plugin.PluginFactory;
 
 /**
  * Factory for creating a plugin for a duplex transport.
  */
 @NotNullByDefault
-public interface DuplexPluginFactory {
-
-	/**
-	 * Returns the plugin's transport identifier.
-	 */
-	TransportId getId();
-
-	/**
-	 * Returns the maximum latency of the transport in milliseconds.
-	 */
-	int getMaxLatency();
-
-	/**
-	 * Creates and returns a plugin, or null if no plugin can be created.
-	 */
-	@Nullable
-	DuplexPlugin createPlugin(PluginCallback callback);
+public interface DuplexPluginFactory extends PluginFactory<DuplexPlugin> {
 }

bramble-api/src/main/java/org/briarproject/bramble/api/plugin/file/FileConstants.java

@@ -1,4 +1,4 @@
-package org.briarproject.bramble.api.plugin;
+package org.briarproject.bramble.api.plugin.file;
 
 public interface FileConstants {
 

bramble-api/src/main/java/org/briarproject/bramble/api/plugin/file/RemovableDriveConstants.java

@@ -0,0 +1,12 @@
+package org.briarproject.bramble.api.plugin.file;
+
+import org.briarproject.bramble.api.plugin.TransportId;
+
+public interface RemovableDriveConstants {
+
+	TransportId ID = new TransportId("org.briarproject.bramble.drive");
+
+	String PROP_PATH = "path";
+	String PROP_URI = "uri";
+	String PROP_SUPPORTED = "supported";
+}

bramble-api/src/main/java/org/briarproject/bramble/api/plugin/file/RemovableDriveManager.java

@@ -0,0 +1,52 @@
+package org.briarproject.bramble.api.plugin.file;
+
+import org.briarproject.bramble.api.contact.ContactId;
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.properties.TransportProperties;
+
+import javax.annotation.Nullable;
+
+@NotNullByDefault
+public interface RemovableDriveManager {
+
+	/**
+	 * Returns the currently running reader task, or null if no reader task
+	 * is running.
+	 */
+	@Nullable
+	RemovableDriveTask getCurrentReaderTask();
+
+	/**
+	 * Returns the currently running writer task,  or null if no writer task
+	 * is running.
+	 */
+	@Nullable
+	RemovableDriveTask getCurrentWriterTask();
+
+	/**
+	 * Starts and returns a reader task, reading from a stream described by
+	 * the given transport properties. If a reader task is already running,
+	 * it will be returned and the argument will be ignored.
+	 */
+	RemovableDriveTask startReaderTask(TransportProperties p);
+
+	/**
+	 * Starts and returns a writer task for the given contact, writing to
+	 * a stream described by the given transport properties. If a writer task
+	 * is already running, it will be returned and the arguments will be
+	 * ignored.
+	 */
+	RemovableDriveTask startWriterTask(ContactId c, TransportProperties p);
+
+	/**
+	 * Returns true if the given contact has indicated support for the
+	 * removable drive transport.
+	 */
+	boolean isTransportSupportedByContact(ContactId c) throws DbException;
+
+	/**
+	 * Returns true if there is anything to send to the given contact.
+	 */
+	boolean isWriterTaskNeeded(ContactId c) throws DbException;
+}

bramble-api/src/main/java/org/briarproject/bramble/api/plugin/file/RemovableDriveTask.java

@@ -0,0 +1,65 @@
+package org.briarproject.bramble.api.plugin.file;
+
+import org.briarproject.bramble.api.Consumer;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.properties.TransportProperties;
+
+@NotNullByDefault
+public interface RemovableDriveTask extends Runnable {
+
+	/**
+	 * Returns the {@link TransportProperties} that were used for creating
+	 * this task.
+	 */
+	TransportProperties getTransportProperties();
+
+	/**
+	 * 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<State> observer);
+
+	/**
+	 * Removes an observer from the task.
+	 */
+	void removeObserver(Consumer<State> observer);
+
+	class State {
+
+		private final long done, total;
+		private final boolean finished, success;
+
+		public State(long done, long total, boolean finished, boolean success) {
+			this.done = done;
+			this.total = total;
+			this.finished = finished;
+			this.success = success;
+		}
+
+		/**
+		 * Returns the total length in bytes of the messages read or written
+		 * so far, or zero if the total is unknown.
+		 */
+		public long getDone() {
+			return done;
+		}
+
+		/**
+		 * Returns the total length in bytes of the messages that will have
+		 * been read or written when the task is complete, or zero if the
+		 * total is unknown.
+		 */
+		public long getTotal() {
+			return total;
+		}
+
+		public boolean isFinished() {
+			return finished;
+		}
+
+		public boolean isSuccess() {
+			return success;
+		}
+	}
+}

bramble-api/src/main/java/org/briarproject/bramble/api/plugin/simplex/SimplexPlugin.java

@@ -15,6 +15,12 @@ import javax.annotation.Nullable;
 @NotNullByDefault
 public interface SimplexPlugin extends Plugin {
 
+	/**
+	 * Returns true if the transport is likely to lose streams and the cost of
+	 * transmitting redundant copies of data is cheap.
+	 */
+	boolean isLossyAndCheap();
+
 	/**
 	 * Attempts to create and return a reader for the given transport
 	 * properties. Returns null if a reader cannot be created.

bramble-api/src/main/java/org/briarproject/bramble/api/plugin/simplex/SimplexPluginFactory.java

@@ -1,30 +1,11 @@
 package org.briarproject.bramble.api.plugin.simplex;
 
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.plugin.PluginCallback;
-import org.briarproject.bramble.api.plugin.TransportId;
-
-import javax.annotation.Nullable;
+import org.briarproject.bramble.api.plugin.PluginFactory;
 
 /**
  * Factory for creating a plugin for a simplex transport.
  */
 @NotNullByDefault
-public interface SimplexPluginFactory {
-
-	/**
-	 * Returns the plugin's transport identifier.
-	 */
-	TransportId getId();
-
-	/**
-	 * Returns the maximum latency of the transport in milliseconds.
-	 */
-	int getMaxLatency();
-
-	/**
-	 * Creates and returns a plugin, or null if no plugin can be created.
-	 */
-	@Nullable
-	SimplexPlugin createPlugin(PluginCallback callback);
+public interface SimplexPluginFactory extends PluginFactory<SimplexPlugin> {
 }

bramble-api/src/main/java/org/briarproject/bramble/api/properties/TransportPropertyManager.java

@@ -74,13 +74,6 @@ public interface TransportPropertyManager {
 	TransportProperties getRemoteProperties(ContactId c, TransportId t)
 			throws DbException;
 
-	/**
-	 * Returns the remote transport properties for the given contact and
-	 * transport.
-	 */
-	TransportProperties getRemoteProperties(Transaction txn, ContactId c,
-			TransportId t) throws DbException;
-
 	/**
 	 * Merges the given properties with the existing local properties for the
 	 * given transport.

bramble-api/src/main/java/org/briarproject/bramble/api/reporting/ReportingConstants.java

@@ -21,5 +21,6 @@ public interface ReportingConstants {
 	 * Hidden service address for reporting crashes and feedback to the
 	 * developers.
 	 */
-	String DEV_ONION_ADDRESS = "cwqmubyvnig3wag3.onion";
+	String DEV_ONION_ADDRESS =
+			"b2nkt5doeamvdmjzfz7g42hk5vdtlnktlgzhel2bgjcc4v4jhnx2qrqd.onion";
 }

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

@@ -5,6 +5,7 @@ import org.briarproject.bramble.api.UniqueId;
 import java.util.List;
 
 import static java.util.Collections.singletonList;
+import static java.util.concurrent.TimeUnit.DAYS;
 import static org.briarproject.bramble.api.record.Record.MAX_RECORD_PAYLOAD_BYTES;
 
 public interface SyncConstants {
@@ -55,4 +56,9 @@ public interface SyncConstants {
 	 * connections.
 	 */
 	int PRIORITY_NONCE_BYTES = 16;
+
+	/**
+	 * The maximum allowed latency for any transport, in milliseconds.
+	 */
+	long MAX_TRANSPORT_LATENCY = DAYS.toMillis(365);
 }

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

@@ -16,9 +16,9 @@ public interface SyncSessionFactory {
 			PriorityHandler handler);
 
 	SyncSession createSimplexOutgoingSession(ContactId c, TransportId t,
-			int maxLatency, StreamWriter streamWriter);
+			long maxLatency, boolean eager, StreamWriter streamWriter);
 
 	SyncSession createDuplexOutgoingSession(ContactId c, TransportId t,
-			int maxLatency, int maxIdleTime, StreamWriter streamWriter,
+			long maxLatency, int maxIdleTime, StreamWriter streamWriter,
 			@Nullable Priority priority);
 }

bramble-api/src/main/java/org/briarproject/bramble/api/sync/event/MessagesSentEvent.java

@@ -18,11 +18,13 @@ public class MessagesSentEvent extends Event {
 
 	private final ContactId contactId;
 	private final Collection<MessageId> messageIds;
+	private final long totalLength;
 
 	public MessagesSentEvent(ContactId contactId,
-			Collection<MessageId> messageIds) {
+			Collection<MessageId> messageIds, long totalLength) {
 		this.contactId = contactId;
 		this.messageIds = messageIds;
+		this.totalLength = totalLength;
 	}
 
 	public ContactId getContactId() {
@@ -32,4 +34,8 @@ public class MessagesSentEvent extends Event {
 	public Collection<MessageId> getMessageIds() {
 		return messageIds;
 	}
+
+	public long getTotalLength() {
+		return totalLength;
+	}
 }

bramble-api/src/main/java/org/briarproject/bramble/api/sync/validation/IncomingMessageHook.java

@@ -10,23 +10,54 @@ public interface IncomingMessageHook {
 
 	/**
 	 * Called once for each incoming message that passes validation.
+	 * <p>
+	 * If an unexpected exception occurs while handling data that is assumed
+	 * to be valid (e.g. locally created metadata), it may be sensible to
+	 * rethrow the unexpected exception as a DbException so that delivery is
+	 * attempted again at next startup. This will allow delivery to succeed if
+	 * the unexpected exception was caused by a bug that has subsequently been
+	 * fixed.
 	 *
 	 * @param txn A read-write transaction
-	 * @return Whether or not this message should be shared
-	 * @throws DbException Should only be used for real database errors.
-	 * If this is thrown, delivery will be attempted again at next startup,
-	 * whereas if an InvalidMessageException is thrown,
-	 * the message will be permanently invalidated.
-	 * @throws InvalidMessageException for any non-database error
-	 * that occurs while handling remotely created data.
-	 * This includes errors that occur while handling locally created data
-	 * in a context controlled by remotely created data
-	 * (for example, parsing the metadata of a dependency
-	 * of an incoming message).
-	 * Throwing this will delete the incoming message and its metadata
-	 * marking it as invalid in the database.
-	 * Never rethrow DbException as InvalidMessageException!
+	 * @throws DbException if a database error occurs while delivering the
+	 * message. Delivery will be attempted again at next startup. Throwing
+	 * this exception has the same effect as returning
+	 * {@link DeliveryAction#DEFER}.
+	 * @throws InvalidMessageException if the message is invalid in the context
+	 * of its dependencies. The message and any dependents will be marked as
+	 * invalid and deleted along with their metadata. Throwing this exception
+	 * has the same effect as returning {@link DeliveryAction#REJECT}.
 	 */
-	boolean incomingMessage(Transaction txn, Message m, Metadata meta)
+	DeliveryAction incomingMessage(Transaction txn, Message m, Metadata meta)
 			throws DbException, InvalidMessageException;
+
+	enum DeliveryAction {
+
+		/**
+		 * The message and any dependent messages will be moved to the
+		 * {@link MessageState#INVALID INVALID state} and deleted, along with
+		 * their metadata.
+		 */
+		REJECT,
+
+		/**
+		 * The message will be moved to the
+		 * {@link MessageState#PENDING PENDING state}. Delivery will be
+		 * attempted again at next startup.
+		 */
+		DEFER,
+
+		/**
+		 * The message will be moved to the
+		 * {@link MessageState#DELIVERED DELIVERED state} and shared.
+		 */
+		ACCEPT_SHARE,
+
+		/**
+		 * The message will be moved to the
+		 * {@link MessageState#DELIVERED DELIVERED state} and will not be
+		 * shared.
+		 */
+		ACCEPT_DO_NOT_SHARE
+	}
 }

bramble-api/src/main/java/org/briarproject/bramble/api/sync/validation/MessageState.java

@@ -1,8 +1,33 @@
 package org.briarproject.bramble.api.sync.validation;
 
+import org.briarproject.bramble.api.sync.validation.IncomingMessageHook.DeliveryAction;
+
 public enum MessageState {
 
-	UNKNOWN(0), INVALID(1), PENDING(2), DELIVERED(3);
+	/**
+	 * A remote message that has not yet been validated.
+	 */
+	UNKNOWN(0),
+
+	/**
+	 * A remote message that has failed validation, has been
+	 * {@link DeliveryAction#REJECT rejected} by the local sync client, or
+	 * depends on another message that has failed validation or been rejected.
+	 */
+	INVALID(1),
+
+	/**
+	 * A remote message that has passed validation and is awaiting delivery to
+	 * the local sync client. The message will not be delivered until all its
+	 * dependencies have been validated and delivered.
+	 */
+	PENDING(2),
+
+	/**
+	 * A local message, or a remote message that has passed validation and
+	 * been delivered to the local sync client.
+	 */
+	DELIVERED(3);
 
 	private final int value;
 

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

@@ -6,6 +6,22 @@ package org.briarproject.bramble.api.system;
  */
 public interface Clock {
 
+	/**
+	 * The minimum reasonable value for the system clock, in milliseconds
+	 * since the Unix epoch.
+	 * <p/>
+	 * 1 Jan 2021, 00:00:00 UTC
+	 */
+	long MIN_REASONABLE_TIME_MS = 1_609_459_200_000L;
+
+	/**
+	 * The maximum reasonable value for the system clock, in milliseconds
+	 * since the Unix epoch.
+	 * <p/>
+	 * 1 Jan 2121, 00:00:00 UTC
+	 */
+	long MAX_REASONABLE_TIME_MS = 4_765_132_800_000L;
+
 	/**
 	 * @see System#currentTimeMillis()
 	 */

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

@@ -22,8 +22,24 @@ public interface KeyManager {
 
 	/**
 	 * Derives and stores a set of rotation mode transport keys for
-	 * communicating with the given contact over each transport and returns the
-	 * key set IDs.
+	 * communicating with the given contact over the given transport and
+	 * returns the key set ID, or null if the transport is not supported.
+	 * <p/>
+	 * {@link StreamContext StreamContexts} for the contact can be created
+	 * after this method has returned.
+	 *
+	 * @param alice True if the local party is Alice
+	 * @param active Whether the derived keys can be used for outgoing streams
+	 */
+	@Nullable
+	KeySetId addRotationKeys(Transaction txn, ContactId c, TransportId t,
+			SecretKey rootKey, long timestamp, boolean alice,
+			boolean active) throws DbException;
+
+	/**
+	 * Derives and stores a set of rotation mode transport keys for
+	 * communicating with the given contact over each supported transport and
+	 * returns the key set IDs.
 	 * <p/>
 	 * {@link StreamContext StreamContexts} for the contact can be created
 	 * after this method has returned.

bramble-api/src/main/java/org/briarproject/bramble/api/transport/agreement/TransportKeyAgreementManager.java

@@ -0,0 +1,24 @@
+package org.briarproject.bramble.api.transport.agreement;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.sync.ClientId;
+
+@NotNullByDefault
+public interface TransportKeyAgreementManager {
+
+	/**
+	 * The unique ID of the transport key agreement client.
+	 */
+	ClientId CLIENT_ID =
+			new ClientId("org.briarproject.bramble.transport.agreement");
+
+	/**
+	 * The current major version of the transport key agreement client.
+	 */
+	int MAJOR_VERSION = 0;
+
+	/**
+	 * The current minor version of the transport key agreement client.
+	 */
+	int MINOR_VERSION = 0;
+}

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

@@ -6,7 +6,9 @@ import org.briarproject.bramble.api.data.BdfList;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 
 import javax.annotation.Nullable;
+import javax.annotation.concurrent.Immutable;
 
+@Immutable
 @NotNullByDefault
 public class ValidationUtils {
 
@@ -64,4 +66,9 @@ public class ValidationUtils {
 		if (dictionary != null && dictionary.size() != size)
 			throw new FormatException();
 	}
+
+	public static void checkRange(@Nullable Long l, long min, long max)
+			throws FormatException {
+		if (l != null && (l < min || l > max)) throw new FormatException();
+	}
 }

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

@@ -163,10 +163,15 @@ public class TestUtils {
 
 	public static Message getMessage(GroupId groupId) {
 		int bodyLength = 1 + random.nextInt(MAX_MESSAGE_BODY_LENGTH);
-		return getMessage(groupId, bodyLength);
+		return getMessage(groupId, bodyLength, timestamp);
 	}
 
 	public static Message getMessage(GroupId groupId, int bodyLength) {
+		return getMessage(groupId, bodyLength, timestamp);
+	}
+
+	public static Message getMessage(GroupId groupId, int bodyLength,
+			long timestamp) {
 		MessageId id = new MessageId(getRandomId());
 		byte[] body = getRandomBytes(bodyLength);
 		return new Message(id, groupId, timestamp, body);

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

@@ -0,0 +1,8 @@
+package org.briarproject.bramble.test;
+
+public interface TimeTravel {
+
+	void setCurrentTimeMillis(long now) throws InterruptedException;
+
+	void addCurrentTimeMillis(long add) throws InterruptedException;
+}

bramble-api/witness.gradle

@@ -1,24 +1,27 @@
 dependencyVerification {
     verify = [
-        'cglib:cglib:3.2.0:cglib-3.2.0.jar:adb13bab79712ad6bdf1bd59f2a3918018a8016e722e8a357065afb9e6690861',
+        'cglib:cglib:3.2.8:cglib-3.2.8.jar:3f64de999ecc5595dc84ca8ff0879d8a34c8623f9ef3c517a53ed59023fcb9db',
+        '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:2.24:dagger-2.24.jar:550a6e46a6dfcdf1d764887b6090cea94f783327e50e5c73754f18facfc70b64',
+        'com.google.dagger:dagger:2.33:dagger-2.33.jar:d8798c5b8cf6b125234e33af5c6293bb9f2208ce29b57924c35b8c0be7b6bdcb',
         'javax.inject:javax.inject:1:javax.inject-1.jar:91c77044a50c481636c32d916fd89c9118a72195390452c81065080f957de7ff',
-        'junit:junit:4.12:junit-4.12.jar:59721f0805e223d84b90677887d9ff567dc534d7c502ca903c0c2b17f05c116a',
-        'org.apache.ant:ant-launcher:1.9.4:ant-launcher-1.9.4.jar:7bccea20b41801ca17bcbc909a78c835d0f443f12d639c77bd6ae3d05861608d',
-        'org.apache.ant:ant:1.9.4:ant-1.9.4.jar:649ae0730251de07b8913f49286d46bba7b92d47c5f332610aa426c4f02161d8',
-        'org.beanshell:bsh:1.3.0:bsh-1.3.0.jar:9b04edc75d19db54f1b4e8b5355e9364384c6cf71eb0a1b9724c159d779879f8',
+        'junit:junit:4.13.2:junit-4.13.2.jar:8e495b634469d64fb8acfa3495a065cbacc8a0fff55ce1e31007be4c16dc57d3',
+        'net.bytebuddy:byte-buddy:1.9.12:byte-buddy-1.9.12.jar:3688c3d434bebc3edc5516296a2ed0f47b65e451071b4afecad84f902f0efc11',
+        'net.jcip:jcip-annotations:1.0:jcip-annotations-1.0.jar:be5805392060c71474bf6c9a67a099471274d30b83eef84bfc4e0889a4f1dcc0',
+        'org.apache-extras.beanshell:bsh:2.0b6:bsh-2.0b6.jar:a17955976070c0573235ee662f2794a78082758b61accffce8d3f8aedcd91047',
         'org.codehaus.mojo.signature:java16:1.1:java16-1.1.signature:53799223a2c98dba2d0add810bed76315460df285c69e4f397ae6098f87dd619',
         'org.codehaus.mojo:animal-sniffer-ant-tasks:1.16:animal-sniffer-ant-tasks-1.16.jar:890040976fbe2d584619a6a61b1fd2e925b3b5eb342a85eb2762c467c0d64e90',
         'org.codehaus.mojo:animal-sniffer:1.16:animal-sniffer-1.16.jar:72be8bcc226ba43b937c722a08a07852bfa1b11400089265d5df0ee7b38b1d52',
-        'org.hamcrest:hamcrest-core:1.3:hamcrest-core-1.3.jar:66fdef91e9739348df7a096aa384a5685f4e875584cce89386a7a47251c4d8e9',
-        'org.hamcrest:hamcrest-library:1.3:hamcrest-library-1.3.jar:711d64522f9ec410983bd310934296da134be4254a125080a0416ec178dfad1c',
-        'org.jmock:jmock-junit4:2.8.2:jmock-junit4-2.8.2.jar:f7ee4df4f7bd7b7f1cafad3b99eb74d579f109d5992ff625347352edb55e674c',
-        'org.jmock:jmock-legacy:2.8.2:jmock-legacy-2.8.2.jar:f2b985a5c08a9edb7f37612330c058809da3f6a6d63ce792426ebf8ff0d6d31b',
-        'org.jmock:jmock-testjar:2.8.2:jmock-testjar-2.8.2.jar:8900860f72c474e027cf97fe78dcbf154a1aa7fc62b6845c5fb4e4f3c7bc8760',
-        'org.jmock:jmock:2.8.2:jmock-2.8.2.jar:6c73cb4a2e6dbfb61fd99c9a768539c170ab6568e57846bd60dbf19596b65b16',
-        'org.objenesis:objenesis:2.1:objenesis-2.1.jar:c74330cc6b806c804fd37e74487b4fe5d7c2750c5e15fbc6efa13bdee1bdef80',
+        '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.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.objenesis:objenesis:3.0.1:objenesis-3.0.1.jar:7a8ff780b9ff48415d7c705f60030b0acaa616e7f823c98eede3b63508d4e984',
         'org.ow2.asm:asm-all:5.2:asm-all-5.2.jar:7fbffbc1db3422e2101689fd88df8384b15817b52b9b2b267b9f6d2511dc198d',
-        'org.ow2.asm:asm:5.0.4:asm-5.0.4.jar:896618ed8ae62702521a78bc7be42b7c491a08e6920a15f89a3ecdec31e9a220',
+        'org.ow2.asm:asm:7.1:asm-7.1.jar:4ab2fa2b6d2cc9ccb1eaa05ea329c407b47b13ed2915f62f8c4b8cc96258d4de',
     ]
 }

bramble-core/build.gradle

@@ -17,16 +17,17 @@ dependencies {
 	implementation 'org.whispersystems:curve25519-java:0.5.0'
 	implementation 'org.briarproject:jtorctl:0.3'
 
-	annotationProcessor 'com.google.dagger:dagger-compiler:2.24'
+	annotationProcessor "com.google.dagger:dagger-compiler:$dagger_version"
 
 	testImplementation project(path: ':bramble-api', configuration: 'testOutput')
 	testImplementation 'org.hsqldb:hsqldb:2.3.5' // The last version that supports Java 1.6
-	testImplementation 'junit:junit:4.12'
-	testImplementation "org.jmock:jmock:2.8.2"
-	testImplementation "org.jmock:jmock-junit4:2.8.2"
-	testImplementation "org.jmock:jmock-legacy:2.8.2"
+	testImplementation 'net.jodah:concurrentunit:0.4.2'
+	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"
 
-	testAnnotationProcessor 'com.google.dagger:dagger-compiler:2.24'
+	testAnnotationProcessor "com.google.dagger:dagger-compiler:$dagger_version"
 
 	signature 'org.codehaus.mojo.signature:java16:1.1@signature'
 }

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

@@ -1,5 +1,6 @@
 package org.briarproject.bramble;
 
+import org.briarproject.bramble.cleanup.CleanupModule;
 import org.briarproject.bramble.contact.ContactModule;
 import org.briarproject.bramble.crypto.CryptoExecutorModule;
 import org.briarproject.bramble.db.DatabaseExecutorModule;
@@ -10,10 +11,13 @@ import org.briarproject.bramble.properties.PropertiesModule;
 import org.briarproject.bramble.rendezvous.RendezvousModule;
 import org.briarproject.bramble.sync.validation.ValidationModule;
 import org.briarproject.bramble.transport.TransportModule;
+import org.briarproject.bramble.transport.agreement.TransportKeyAgreementModule;
 import org.briarproject.bramble.versioning.VersioningModule;
 
 public interface BrambleCoreEagerSingletons {
 
+	void inject(CleanupModule.EagerSingletons init);
+
 	void inject(ContactModule.EagerSingletons init);
 
 	void inject(CryptoExecutorModule.EagerSingletons init);
@@ -30,6 +34,8 @@ public interface BrambleCoreEagerSingletons {
 
 	void inject(RendezvousModule.EagerSingletons init);
 
+	void inject(TransportKeyAgreementModule.EagerSingletons init);
+
 	void inject(TransportModule.EagerSingletons init);
 
 	void inject(ValidationModule.EagerSingletons init);
@@ -39,6 +45,7 @@ public interface BrambleCoreEagerSingletons {
 	class Helper {
 
 		public static void injectEagerSingletons(BrambleCoreEagerSingletons c) {
+			c.inject(new CleanupModule.EagerSingletons());
 			c.inject(new ContactModule.EagerSingletons());
 			c.inject(new CryptoExecutorModule.EagerSingletons());
 			c.inject(new DatabaseExecutorModule.EagerSingletons());
@@ -47,6 +54,7 @@ public interface BrambleCoreEagerSingletons {
 			c.inject(new RendezvousModule.EagerSingletons());
 			c.inject(new PluginModule.EagerSingletons());
 			c.inject(new PropertiesModule.EagerSingletons());
+			c.inject(new TransportKeyAgreementModule.EagerSingletons());
 			c.inject(new TransportModule.EagerSingletons());
 			c.inject(new ValidationModule.EagerSingletons());
 			c.inject(new VersioningModule.EagerSingletons());

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

@@ -1,5 +1,6 @@
 package org.briarproject.bramble;
 
+import org.briarproject.bramble.cleanup.CleanupModule;
 import org.briarproject.bramble.client.ClientModule;
 import org.briarproject.bramble.connection.ConnectionModule;
 import org.briarproject.bramble.contact.ContactModule;
@@ -21,15 +22,15 @@ import org.briarproject.bramble.rendezvous.RendezvousModule;
 import org.briarproject.bramble.settings.SettingsModule;
 import org.briarproject.bramble.sync.SyncModule;
 import org.briarproject.bramble.sync.validation.ValidationModule;
-import org.briarproject.bramble.system.ClockModule;
 import org.briarproject.bramble.transport.TransportModule;
+import org.briarproject.bramble.transport.agreement.TransportKeyAgreementModule;
 import org.briarproject.bramble.versioning.VersioningModule;
 
 import dagger.Module;
 
 @Module(includes = {
+		CleanupModule.class,
 		ClientModule.class,
-		ClockModule.class,
 		ConnectionModule.class,
 		ContactModule.class,
 		CryptoModule.class,
@@ -49,6 +50,7 @@ import dagger.Module;
 		RendezvousModule.class,
 		SettingsModule.class,
 		SyncModule.class,
+		TransportKeyAgreementModule.class,
 		TransportModule.class,
 		ValidationModule.class,
 		VersioningModule.class

bramble-core/src/main/java/org/briarproject/bramble/cleanup/CleanupManagerImpl.java

@@ -0,0 +1,159 @@
+package org.briarproject.bramble.cleanup;
+
+import org.briarproject.bramble.api.cleanup.CleanupHook;
+import org.briarproject.bramble.api.cleanup.CleanupManager;
+import org.briarproject.bramble.api.cleanup.event.CleanupTimerStartedEvent;
+import org.briarproject.bramble.api.db.DatabaseComponent;
+import org.briarproject.bramble.api.db.DatabaseExecutor;
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.db.Transaction;
+import org.briarproject.bramble.api.event.Event;
+import org.briarproject.bramble.api.event.EventListener;
+import org.briarproject.bramble.api.lifecycle.Service;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.sync.ClientId;
+import org.briarproject.bramble.api.sync.Group;
+import org.briarproject.bramble.api.sync.GroupId;
+import org.briarproject.bramble.api.sync.MessageId;
+import org.briarproject.bramble.api.system.Clock;
+import org.briarproject.bramble.api.system.TaskScheduler;
+import org.briarproject.bramble.api.versioning.ClientMajorVersion;
+
+import java.util.Collection;
+import java.util.HashSet;
+import java.util.Map;
+import java.util.Map.Entry;
+import java.util.Set;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.Executor;
+import java.util.logging.Logger;
+
+import javax.annotation.concurrent.GuardedBy;
+import javax.annotation.concurrent.ThreadSafe;
+import javax.inject.Inject;
+
+import static java.lang.Math.max;
+import static java.util.concurrent.TimeUnit.MILLISECONDS;
+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.util.LogUtils.logException;
+
+@ThreadSafe
+@NotNullByDefault
+class CleanupManagerImpl implements CleanupManager, Service, EventListener {
+
+	private static final Logger LOG =
+			getLogger(CleanupManagerImpl.class.getName());
+
+	private final Executor dbExecutor;
+	private final DatabaseComponent db;
+	private final TaskScheduler taskScheduler;
+	private final Clock clock;
+	private final Map<ClientMajorVersion, CleanupHook> hooks =
+			new ConcurrentHashMap<>();
+	private final Object lock = new Object();
+
+	@GuardedBy("lock")
+	private final Set<CleanupTask> pending = new HashSet<>();
+
+	@Inject
+	CleanupManagerImpl(@DatabaseExecutor Executor dbExecutor,
+			DatabaseComponent db, TaskScheduler taskScheduler, Clock clock) {
+		this.dbExecutor = dbExecutor;
+		this.db = db;
+		this.taskScheduler = taskScheduler;
+		this.clock = clock;
+	}
+
+	@Override
+	public void registerCleanupHook(ClientId c, int majorVersion,
+			CleanupHook hook) {
+		hooks.put(new ClientMajorVersion(c, majorVersion), hook);
+	}
+
+	@Override
+	public void startService() {
+		maybeScheduleTask(clock.currentTimeMillis());
+	}
+
+	@Override
+	public void stopService() {
+	}
+
+	@Override
+	public void eventOccurred(Event e) {
+		if (e instanceof CleanupTimerStartedEvent) {
+			CleanupTimerStartedEvent a = (CleanupTimerStartedEvent) e;
+			maybeScheduleTask(a.getCleanupDeadline());
+		}
+	}
+
+	private void maybeScheduleTask(long deadline) {
+		synchronized (lock) {
+			for (CleanupTask task : pending) {
+				if (task.deadline <= deadline) return;
+			}
+			CleanupTask task = new CleanupTask(deadline);
+			pending.add(task);
+			scheduleTask(task);
+		}
+	}
+
+	private void scheduleTask(CleanupTask task) {
+		long now = clock.currentTimeMillis();
+		long delay = max(0, task.deadline - now + BATCH_DELAY_MS);
+		if (LOG.isLoggable(INFO)) {
+			LOG.info("Scheduling cleanup task in " + delay + " ms");
+		}
+		taskScheduler.schedule(() -> deleteMessagesAndScheduleNextTask(task),
+				dbExecutor, delay, MILLISECONDS);
+	}
+
+	private void deleteMessagesAndScheduleNextTask(CleanupTask task) {
+		try {
+			synchronized (lock) {
+				pending.remove(task);
+			}
+			long deadline = db.transactionWithResult(false, txn -> {
+				deleteMessages(txn);
+				return db.getNextCleanupDeadline(txn);
+			});
+			if (deadline != NO_CLEANUP_DEADLINE) {
+				maybeScheduleTask(deadline);
+			}
+		} catch (DbException e) {
+			logException(LOG, WARNING, e);
+		}
+	}
+
+	private void deleteMessages(Transaction txn) throws DbException {
+		Map<GroupId, Collection<MessageId>> ids = db.getMessagesToDelete(txn);
+		for (Entry<GroupId, Collection<MessageId>> e : ids.entrySet()) {
+			GroupId groupId = e.getKey();
+			Collection<MessageId> messageIds = e.getValue();
+			if (LOG.isLoggable(INFO)) {
+				LOG.info(messageIds.size() + " messages to delete");
+			}
+			for (MessageId m : messageIds) db.stopCleanupTimer(txn, m);
+			Group group = db.getGroup(txn, groupId);
+			ClientMajorVersion cv = new ClientMajorVersion(group.getClientId(),
+					group.getMajorVersion());
+			CleanupHook hook = hooks.get(cv);
+			if (hook == null) {
+				throw new IllegalStateException("No cleanup hook for " + cv);
+			}
+			hook.deleteMessages(txn, groupId, messageIds);
+		}
+	}
+
+	private static class CleanupTask {
+
+		private final long deadline;
+
+		private CleanupTask(long deadline) {
+			this.deadline = deadline;
+		}
+	}
+}

bramble-core/src/main/java/org/briarproject/bramble/cleanup/CleanupModule.java

@@ -0,0 +1,29 @@
+package org.briarproject.bramble.cleanup;
+
+import org.briarproject.bramble.api.cleanup.CleanupManager;
+import org.briarproject.bramble.api.event.EventBus;
+import org.briarproject.bramble.api.lifecycle.LifecycleManager;
+
+import javax.inject.Inject;
+import javax.inject.Singleton;
+
+import dagger.Module;
+import dagger.Provides;
+
+@Module
+public class CleanupModule {
+
+	public static class EagerSingletons {
+		@Inject
+		CleanupManager cleanupManager;
+	}
+
+	@Provides
+	@Singleton
+	CleanupManager provideCleanupManager(LifecycleManager lifecycleManager,
+			EventBus eventBus, CleanupManagerImpl cleanupManager) {
+		lifecycleManager.registerService(cleanupManager);
+		eventBus.addListener(cleanupManager);
+		return cleanupManager;
+	}
+}

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

@@ -2,11 +2,13 @@ package org.briarproject.bramble.client;
 
 import org.briarproject.bramble.api.FormatException;
 import org.briarproject.bramble.api.client.ClientHelper;
+import org.briarproject.bramble.api.contact.ContactId;
 import org.briarproject.bramble.api.crypto.CryptoComponent;
 import org.briarproject.bramble.api.crypto.KeyParser;
 import org.briarproject.bramble.api.crypto.PrivateKey;
 import org.briarproject.bramble.api.crypto.PublicKey;
 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.BdfReader;
 import org.briarproject.bramble.api.data.BdfReaderFactory;
@@ -32,6 +34,7 @@ import java.io.ByteArrayInputStream;
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
 import java.security.GeneralSecurityException;
+import java.util.Collection;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.Map.Entry;
@@ -39,6 +42,7 @@ import java.util.Map.Entry;
 import javax.annotation.concurrent.Immutable;
 import javax.inject.Inject;
 
+import static org.briarproject.bramble.api.client.ContactGroupConstants.GROUP_KEY_CONTACT_ID;
 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;
@@ -151,6 +155,12 @@ class ClientHelperImpl implements ClientHelper {
 		return metadataParser.parse(metadata);
 	}
 
+	@Override
+	public Collection<MessageId> getMessageIds(Transaction txn, GroupId g,
+			BdfDictionary query) throws DbException, FormatException {
+		return db.getMessageIds(txn, g, metadataEncoder.encode(query));
+	}
+
 	@Override
 	public BdfDictionary getMessageMetadataAsDictionary(MessageId m)
 			throws DbException, FormatException {
@@ -389,4 +399,27 @@ class ClientHelperImpl implements ClientHelper {
 		return tpMap;
 	}
 
+	@Override
+	public ContactId getContactId(Transaction txn, GroupId contactGroupId)
+			throws DbException {
+		try {
+			BdfDictionary meta =
+					getGroupMetadataAsDictionary(txn, contactGroupId);
+			return new ContactId(meta.getLong(GROUP_KEY_CONTACT_ID).intValue());
+		} catch (FormatException e) {
+			throw new DbException(e); // Invalid group metadata
+		}
+	}
+
+	@Override
+	public void setContactId(Transaction txn, GroupId contactGroupId,
+			ContactId c) throws DbException {
+		BdfDictionary meta = BdfDictionary.of(
+				new BdfEntry(GROUP_KEY_CONTACT_ID, c.getInt()));
+		try {
+			mergeGroupMetadata(txn, contactGroupId, meta);
+		} catch (FormatException e) {
+			throw new AssertionError(e);
+		}
+	}
 }

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

@@ -45,7 +45,6 @@ abstract class Connection {
 	@Nullable
 	StreamContext recogniseTag(TransportConnectionReader reader,
 			TransportId transportId) {
-		StreamContext ctx;
 		try {
 			byte[] tag = readTag(reader.getInputStream());
 			return keyManager.getStreamContext(transportId, tag);

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

@@ -71,8 +71,10 @@ class OutgoingSimplexSyncConnection extends SyncConnection implements Runnable {
 		StreamWriter streamWriter = streamWriterFactory.createStreamWriter(
 				w.getOutputStream(), ctx);
 		ContactId c = requireNonNull(ctx.getContactId());
+		// Use eager retransmission if the transport is lossy and cheap
 		return syncSessionFactory.createSimplexOutgoingSession(c,
-				ctx.getTransportId(), w.getMaxLatency(), streamWriter);
+				ctx.getTransportId(), w.getMaxLatency(), w.isLossyAndCheap(),
+				streamWriter);
 	}
 }
 

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

@@ -47,6 +47,7 @@ import javax.inject.Inject;
 
 import static java.util.logging.Logger.getLogger;
 import static org.briarproject.bramble.api.identity.AuthorConstants.MAX_SIGNATURE_LENGTH;
+import static org.briarproject.bramble.api.system.Clock.MIN_REASONABLE_TIME_MS;
 import static org.briarproject.bramble.contact.ContactExchangeConstants.PROTOCOL_VERSION;
 import static org.briarproject.bramble.contact.ContactExchangeRecordTypes.CONTACT_INFO;
 import static org.briarproject.bramble.util.ValidationUtils.checkLength;
@@ -184,6 +185,10 @@ class ContactExchangeManagerImpl implements ContactExchangeManager {
 
 		// The agreed timestamp is the minimum of the peers' timestamps
 		long timestamp = Math.min(localTimestamp, remoteInfo.timestamp);
+		if (timestamp < MIN_REASONABLE_TIME_MS) {
+			LOG.warning("Timestamp is too old");
+			throw new FormatException();
+		}
 
 		// Add the contact
 		Contact contact = addContact(p, remoteInfo.author, localAuthor,

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

@@ -1,11 +1,12 @@
-package org.briarproject.bramble.api.crypto;
+package org.briarproject.bramble.crypto;
 
+import org.briarproject.bramble.api.crypto.SecretKey;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 
 import java.security.GeneralSecurityException;
 
 @NotNullByDefault
-public interface AuthenticatedCipher {
+interface AuthenticatedCipher {
 
 	/**
 	 * Initializes this cipher for encryption or decryption with a key and an

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

@@ -6,7 +6,6 @@ import net.i2p.crypto.eddsa.KeyPairGenerator;
 
 import org.briarproject.bramble.api.crypto.AgreementPrivateKey;
 import org.briarproject.bramble.api.crypto.AgreementPublicKey;
-import org.briarproject.bramble.api.crypto.AuthenticatedCipher;
 import org.briarproject.bramble.api.crypto.CryptoComponent;
 import org.briarproject.bramble.api.crypto.DecryptionException;
 import org.briarproject.bramble.api.crypto.KeyPair;

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

@@ -1,6 +1,5 @@
 package org.briarproject.bramble.crypto;
 
-import org.briarproject.bramble.api.crypto.AuthenticatedCipher;
 import org.briarproject.bramble.api.crypto.CryptoComponent;
 import org.briarproject.bramble.api.crypto.KeyAgreementCrypto;
 import org.briarproject.bramble.api.crypto.PasswordStrengthEstimator;

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

@@ -1,6 +1,5 @@
 package org.briarproject.bramble.crypto;
 
-import org.briarproject.bramble.api.crypto.AuthenticatedCipher;
 import org.briarproject.bramble.api.crypto.SecretKey;
 import org.briarproject.bramble.api.crypto.StreamDecrypter;
 import org.briarproject.bramble.api.crypto.StreamDecrypterFactory;

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

@@ -1,7 +1,6 @@
 package org.briarproject.bramble.crypto;
 
 import org.briarproject.bramble.api.FormatException;
-import org.briarproject.bramble.api.crypto.AuthenticatedCipher;
 import org.briarproject.bramble.api.crypto.SecretKey;
 import org.briarproject.bramble.api.crypto.StreamDecrypter;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;

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

@@ -1,6 +1,5 @@
 package org.briarproject.bramble.crypto;
 
-import org.briarproject.bramble.api.crypto.AuthenticatedCipher;
 import org.briarproject.bramble.api.crypto.CryptoComponent;
 import org.briarproject.bramble.api.crypto.SecretKey;
 import org.briarproject.bramble.api.crypto.StreamEncrypter;

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

@@ -1,6 +1,5 @@
 package org.briarproject.bramble.crypto;
 
-import org.briarproject.bramble.api.crypto.AuthenticatedCipher;
 import org.briarproject.bramble.api.crypto.SecretKey;
 import org.briarproject.bramble.api.crypto.StreamEncrypter;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;

bramble-core/src/main/java/org/briarproject/bramble/crypto/XSalsa20Poly1305AuthenticatedCipher.java

@@ -1,6 +1,5 @@
 package org.briarproject.bramble.crypto;
 
-import org.briarproject.bramble.api.crypto.AuthenticatedCipher;
 import org.briarproject.bramble.api.crypto.SecretKey;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.spongycastle.crypto.DataLengthException;

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

@@ -68,6 +68,13 @@ interface Database<T> {
 	 */
 	void close() throws DbException;
 
+	/**
+	 * Returns true if the dirty flag was set while opening the database,
+	 * indicating that the database has not been shut down properly the last
+	 * time it was closed and some data could be lost.
+	 */
+	boolean wasDirtyOnInitialisation();
+
 	/**
 	 * Starts a new transaction and returns an object representing it.
 	 */
@@ -138,7 +145,7 @@ interface Database<T> {
 	/**
 	 * Stores a transport.
 	 */
-	void addTransport(T txn, TransportId t, int maxLatency)
+	void addTransport(T txn, TransportId t, long maxLatency)
 			throws DbException;
 
 	/**
@@ -155,6 +162,18 @@ interface Database<T> {
 	KeySetId addTransportKeys(T txn, PendingContactId p, TransportKeys k)
 			throws DbException;
 
+	/**
+	 * Returns true if there are any acks or messages to send to the given
+	 * contact over a transport with the given maximum latency.
+	 * <p/>
+	 * Read-only.
+	 *
+	 * @param eager True if messages that are not yet due for retransmission
+	 * should be included
+	 */
+	boolean containsAnythingToSend(T txn, ContactId c, long maxLatency,
+			boolean eager) throws DbException;
+
 	/**
 	 * Returns true if the database contains the given contact for the given
 	 * local pseudonym.
@@ -208,6 +227,16 @@ interface Database<T> {
 	 */
 	boolean containsTransport(T txn, TransportId t) throws DbException;
 
+	/**
+	 * Returns true if the database contains keys for communicating with the
+	 * given contact over the given transport. Handshake mode and rotation mode
+	 * keys are included, whether activated or not.
+	 * <p/>
+	 * Read-only.
+	 */
+	boolean containsTransportKeys(T txn, ContactId c, TransportId t)
+			throws DbException;
+
 	/**
 	 * Returns true if the database contains the given message, the message is
 	 * shared, and the visibility of the message's group to the given contact
@@ -454,7 +483,7 @@ interface Database<T> {
 	 * Read-only.
 	 */
 	Collection<MessageId> getMessagesToOffer(T txn, ContactId c,
-			int maxMessages, int maxLatency) throws DbException;
+			int maxMessages, long maxLatency) throws DbException;
 
 	/**
 	 * Returns the IDs of some messages that are eligible to be requested from
@@ -469,10 +498,36 @@ 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.
 	 * <p/>
+	 * Unlike {@link #getUnackedMessagesToSend(Object, ContactId)} this method
+	 * does not return messages that have already been sent unless they are
+	 * due for retransmission.
+	 * <p/>
 	 * Read-only.
 	 */
 	Collection<MessageId> getMessagesToSend(T txn, ContactId c, int maxLength,
-			int maxLatency) throws DbException;
+			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.
+	 * <p/>
+	 * Unlike {@link #getMessagesToSend(Object, ContactId, int, 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)
+			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
+	 * that have already been sent and are not yet due for retransmission.
+	 * <p/>
+	 * Read-only.
+	 */
+	long getUnackedMessageBytesToSend(T txn, ContactId c) throws DbException;
 
 	/**
 	 * Returns the IDs of any messages that need to be validated.
@@ -497,6 +552,25 @@ interface Database<T> {
 	 */
 	Collection<MessageId> getMessagesToShare(T txn) throws DbException;
 
+	/**
+	 * Returns the IDs of any messages of any messages that are due for
+	 * deletion, along with their group IDs.
+	 * <p/>
+	 * Read-only.
+	 */
+	Map<GroupId, Collection<MessageId>> getMessagesToDelete(T txn)
+			throws DbException;
+
+	/**
+	 * Returns the next time (in milliseconds since the Unix epoch) when a
+	 * message is due to be deleted, or
+	 * {@link DatabaseComponent#NO_CLEANUP_DEADLINE} if no messages are
+	 * scheduled to be deleted.
+	 * <p/>
+	 * Read-only.
+	 */
+	long getNextCleanupDeadline(T txn) throws DbException;
+
 	/**
 	 * Returns the next time (in milliseconds since the Unix epoch) when a
 	 * message is due to be sent to the given contact. The returned value may
@@ -530,7 +604,7 @@ interface Database<T> {
 	 * Read-only.
 	 */
 	Collection<MessageId> getRequestedMessagesToSend(T txn, ContactId c,
-			int maxLength, int maxLatency) throws DbException;
+			int maxLength, long maxLatency) throws DbException;
 
 	/**
 	 * Returns all settings in the given namespace.
@@ -554,6 +628,16 @@ interface Database<T> {
 	Collection<TransportKeySet> getTransportKeys(T txn, TransportId t)
 			throws DbException;
 
+	/**
+	 * Returns the contact IDs and transport IDs for which the DB contains
+	 * at least one set of transport keys. Handshake mode and rotation mode
+	 * keys are included, whether activated or not.
+	 * <p/>
+	 * Read-only.
+	 */
+	Map<ContactId, Collection<TransportId>> getTransportsWithKeys(T txn)
+			throws DbException;
+
 	/**
 	 * Increments the outgoing stream counter for the given transport keys.
 	 */
@@ -606,8 +690,10 @@ interface Database<T> {
 
 	/**
 	 * Marks a message as having been seen by the given contact.
+	 *
+	 * @return True if the message was not already marked as seen.
 	 */
-	void raiseSeenFlag(T txn, ContactId c, MessageId m) throws DbException;
+	boolean raiseSeenFlag(T txn, ContactId c, MessageId m) throws DbException;
 
 	/**
 	 * Removes a contact from the database.
@@ -671,6 +757,13 @@ interface Database<T> {
 	 */
 	void resetExpiryTime(T txn, ContactId c, MessageId m) throws DbException;
 
+	/**
+	 * Sets the cleanup timer duration for the given message. This does not
+	 * start the message's cleanup timer.
+	 */
+	void setCleanupTimerDuration(T txn, MessageId m, long duration)
+			throws DbException;
+
 	/**
 	 * Marks the given contact as verified.
 	 */
@@ -701,9 +794,10 @@ interface Database<T> {
 	void setMessagePermanent(T txn, MessageId m) throws DbException;
 
 	/**
-	 * Marks the given message as shared.
+	 * Marks the given message as shared or not.
 	 */
-	void setMessageShared(T txn, MessageId m) throws DbException;
+	void setMessageShared(T txn, MessageId m, boolean shared)
+			throws DbException;
 
 	/**
 	 * Sets the validation and delivery state of the given message.
@@ -730,12 +824,28 @@ interface Database<T> {
 	void setTransportKeysActive(T txn, TransportId t, KeySetId k)
 			throws DbException;
 
+	/**
+	 * Starts the cleanup timer for the given message, if a timer duration
+	 * has been set and the timer has not already been started.
+	 *
+	 * @return The cleanup deadline, or
+	 * {@link DatabaseComponent#TIMER_NOT_STARTED} if no timer duration has
+	 * been set for this message or its timer has already been started.
+	 */
+	long startCleanupTimer(T txn, MessageId m) throws DbException;
+
+	/**
+	 * Stops the cleanup timer for the given message, if the timer has been
+	 * started.
+	 */
+	void stopCleanupTimer(T txn, MessageId m) throws DbException;
+
 	/**
 	 * Updates the transmission count, expiry time and estimated time of arrival
 	 * of the given message with respect to the given contact, using the latency
 	 * of the transport over which it was sent.
 	 */
-	void updateExpiryTimeAndEta(T txn, ContactId c, MessageId m, int maxLatency)
+	void updateExpiryTimeAndEta(T txn, ContactId c, MessageId m, long maxLatency)
 			throws DbException;
 
 	/**

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

@@ -1,10 +1,12 @@
 package org.briarproject.bramble.db;
 
+import org.briarproject.bramble.api.cleanup.event.CleanupTimerStartedEvent;
 import org.briarproject.bramble.api.contact.Contact;
 import org.briarproject.bramble.api.contact.ContactId;
 import org.briarproject.bramble.api.contact.PendingContact;
 import org.briarproject.bramble.api.contact.PendingContactId;
 import org.briarproject.bramble.api.contact.event.ContactAddedEvent;
+import org.briarproject.bramble.api.contact.event.ContactAliasChangedEvent;
 import org.briarproject.bramble.api.contact.event.ContactRemovedEvent;
 import org.briarproject.bramble.api.contact.event.ContactVerifiedEvent;
 import org.briarproject.bramble.api.contact.event.PendingContactAddedEvent;
@@ -308,7 +310,7 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 
 	@Override
 	public void addTransport(Transaction transaction, TransportId t,
-			int maxLatency) throws DbException {
+			long maxLatency) throws DbException {
 		if (transaction.isReadOnly()) throw new IllegalArgumentException();
 		T txn = unbox(transaction);
 		if (!db.containsTransport(txn, t))
@@ -339,6 +341,15 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 		return db.addTransportKeys(txn, p, k);
 	}
 
+	@Override
+	public boolean containsAnythingToSend(Transaction transaction, ContactId c,
+			long maxLatency, boolean eager) throws DbException {
+		T txn = unbox(transaction);
+		if (!db.containsContact(txn, c))
+			throw new NoSuchContactException();
+		return db.containsAnythingToSend(txn, c, maxLatency, eager);
+	}
+
 	@Override
 	public boolean containsContact(Transaction transaction, AuthorId remote,
 			AuthorId local) throws DbException {
@@ -369,6 +380,13 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 		return db.containsPendingContact(txn, p);
 	}
 
+	@Override
+	public boolean containsTransportKeys(Transaction transaction, ContactId c,
+			TransportId t) throws DbException {
+		T txn = unbox(transaction);
+		return db.containsTransportKeys(txn, c, t);
+	}
+
 	@Override
 	public void deleteMessage(Transaction transaction, MessageId m)
 			throws DbException {
@@ -406,28 +424,57 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 	@Nullable
 	@Override
 	public Collection<Message> generateBatch(Transaction transaction,
-			ContactId c, int maxLength, int maxLatency) throws DbException {
+			ContactId c, int maxLength, 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);
+		long totalLength = 0;
 		List<Message> messages = new ArrayList<>(ids.size());
 		for (MessageId m : ids) {
-			messages.add(db.getMessage(txn, m));
+			Message message = db.getMessage(txn, m);
+			totalLength += message.getRawLength();
+			messages.add(message);
 			db.updateExpiryTimeAndEta(txn, c, m, maxLatency);
 		}
 		if (ids.isEmpty()) return null;
 		db.lowerRequestedFlag(txn, c, ids);
-		transaction.attach(new MessagesSentEvent(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,
-			int maxMessages, int maxLatency) throws DbException {
+			int maxMessages, long maxLatency) throws DbException {
 		if (transaction.isReadOnly()) throw new IllegalArgumentException();
 		T txn = unbox(transaction);
 		if (!db.containsContact(txn, c))
@@ -458,21 +505,24 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 	@Nullable
 	@Override
 	public Collection<Message> generateRequestedBatch(Transaction transaction,
-			ContactId c, int maxLength, int maxLatency) throws DbException {
+			ContactId c, int maxLength, 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);
+		long totalLength = 0;
 		List<Message> messages = new ArrayList<>(ids.size());
 		for (MessageId m : ids) {
-			messages.add(db.getMessage(txn, m));
+			Message message = db.getMessage(txn, m);
+			totalLength += message.getRawLength();
+			messages.add(message);
 			db.updateExpiryTimeAndEta(txn, c, m, maxLatency);
 		}
 		if (ids.isEmpty()) return null;
 		db.lowerRequestedFlag(txn, c, ids);
-		transaction.attach(new MessagesSentEvent(c, ids));
+		transaction.attach(new MessagesSentEvent(c, ids, totalLength));
 		return messages;
 	}
 
@@ -576,6 +626,15 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 		return db.getMessageIds(txn, g);
 	}
 
+	@Override
+	public Collection<MessageId> getMessageIds(Transaction transaction,
+			GroupId g, Metadata query) throws DbException {
+		T txn = unbox(transaction);
+		if (!db.containsGroup(txn, g))
+			throw new NoSuchGroupException();
+		return db.getMessageIds(txn, g, query);
+	}
+
 	@Override
 	public Collection<MessageId> getMessagesToValidate(Transaction transaction)
 			throws DbException {
@@ -597,6 +656,13 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 		return db.getMessagesToShare(txn);
 	}
 
+	@Override
+	public Map<GroupId, Collection<MessageId>> getMessagesToDelete(
+			Transaction transaction) throws DbException {
+		T txn = unbox(transaction);
+		return db.getMessagesToDelete(txn);
+	}
+
 	@Override
 	public Map<MessageId, Metadata> getMessageMetadata(Transaction transaction,
 			GroupId g) throws DbException {
@@ -674,6 +740,25 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 		return status;
 	}
 
+	@Override
+	public Map<MessageId, Integer> 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 long getUnackedMessageBytesToSend(Transaction transaction,
+			ContactId c) throws DbException {
+		T txn = unbox(transaction);
+		if (!db.containsContact(txn, c))
+			throw new NoSuchContactException();
+		return db.getUnackedMessageBytesToSend(txn, c);
+	}
+
 	@Override
 	public Map<MessageId, MessageState> getMessageDependencies(
 			Transaction transaction, MessageId m) throws DbException {
@@ -692,6 +777,13 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 		return db.getMessageDependents(txn, m);
 	}
 
+	@Override
+	public long getNextCleanupDeadline(Transaction transaction)
+			throws DbException {
+		T txn = unbox(transaction);
+		return db.getNextCleanupDeadline(txn);
+	}
+
 	@Override
 	public long getNextSendTime(Transaction transaction, ContactId c)
 			throws DbException {
@@ -740,6 +832,13 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 		return db.getTransportKeys(txn, t);
 	}
 
+	@Override
+	public Map<ContactId, Collection<TransportId>> getTransportsWithKeys(
+			Transaction transaction) throws DbException {
+		T txn = unbox(transaction);
+		return db.getTransportsWithKeys(txn);
+	}
+
 	@Override
 	public void incrementStreamCounter(Transaction transaction, TransportId t,
 			KeySetId k) throws DbException {
@@ -795,8 +894,17 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 		Collection<MessageId> acked = new ArrayList<>();
 		for (MessageId m : a.getMessageIds()) {
 			if (db.containsVisibleMessage(txn, c, m)) {
-				db.raiseSeenFlag(txn, c, m);
-				acked.add(m);
+				if (db.raiseSeenFlag(txn, c, m)) {
+					// This is the first time the message has been acked by
+					// this contact. Start the cleanup timer (a no-op unless
+					// a cleanup deadline has been set for this message)
+					long deadline = db.startCleanupTimer(txn, m);
+					if (deadline != TIMER_NOT_STARTED) {
+						transaction.attach(new CleanupTimerStartedEvent(m,
+								deadline));
+					}
+					acked.add(m);
+				}
 			}
 		}
 		if (acked.size() > 0) {
@@ -952,6 +1060,16 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 		db.removeTransportKeys(txn, t, k);
 	}
 
+	@Override
+	public void setCleanupTimerDuration(Transaction transaction, MessageId m,
+			long duration) throws DbException {
+		if (transaction.isReadOnly()) throw new IllegalArgumentException();
+		T txn = unbox(transaction);
+		if (!db.containsMessage(txn, m))
+			throw new NoSuchMessageException();
+		db.setCleanupTimerDuration(txn, m, duration);
+	}
+
 	@Override
 	public void setContactVerified(Transaction transaction, ContactId c)
 			throws DbException {
@@ -970,6 +1088,7 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 		T txn = unbox(transaction);
 		if (!db.containsContact(txn, c))
 			throw new NoSuchContactException();
+		transaction.attach(new ContactAliasChangedEvent(c, alias));
 		db.setContactAlias(txn, c, alias);
 	}
 
@@ -1001,6 +1120,16 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 		db.setMessagePermanent(txn, m);
 	}
 
+	@Override
+	public void setMessageNotShared(Transaction transaction, MessageId m)
+			throws DbException {
+		if (transaction.isReadOnly()) throw new IllegalArgumentException();
+		T txn = unbox(transaction);
+		if (!db.containsMessage(txn, m))
+			throw new NoSuchMessageException();
+		db.setMessageShared(txn, m, false);
+	}
+
 	@Override
 	public void setMessageShared(Transaction transaction, MessageId m)
 			throws DbException {
@@ -1010,7 +1139,7 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 			throw new NoSuchMessageException();
 		if (db.getMessageState(txn, m) != DELIVERED)
 			throw new IllegalArgumentException("Shared undelivered message");
-		db.setMessageShared(txn, m);
+		db.setMessageShared(txn, m, true);
 		transaction.attach(new MessageSharedEvent(m));
 	}
 
@@ -1082,6 +1211,30 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 		db.setTransportKeysActive(txn, t, k);
 	}
 
+	@Override
+	public long startCleanupTimer(Transaction transaction, MessageId m)
+			throws DbException {
+		if (transaction.isReadOnly()) throw new IllegalArgumentException();
+		T txn = unbox(transaction);
+		if (!db.containsMessage(txn, m))
+			throw new NoSuchMessageException();
+		long deadline = db.startCleanupTimer(txn, m);
+		if (deadline != TIMER_NOT_STARTED) {
+			transaction.attach(new CleanupTimerStartedEvent(m, deadline));
+		}
+		return deadline;
+	}
+
+	@Override
+	public void stopCleanupTimer(Transaction transaction, MessageId m)
+			throws DbException {
+		if (transaction.isReadOnly()) throw new IllegalArgumentException();
+		T txn = unbox(transaction);
+		if (!db.containsMessage(txn, m))
+			throw new NoSuchMessageException();
+		db.stopCleanupTimer(txn, m);
+	}
+
 	@Override
 	public void updateTransportKeys(Transaction transaction,
 			Collection<TransportKeySet> keys) throws DbException {

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

@@ -37,4 +37,10 @@ interface DatabaseConstants {
 	 * 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.
+	 */
+	String DIRTY_KEY = "dirty";
 }

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

@@ -1,5 +1,7 @@
 package org.briarproject.bramble.db;
 
+import static org.briarproject.bramble.api.sync.SyncConstants.MAX_TRANSPORT_LATENCY;
+
 class ExponentialBackoff {
 
 	/**
@@ -11,9 +13,11 @@ class ExponentialBackoff {
 	 * transmissions increases exponentially. If the expiry time would
 	 * be greater than Long.MAX_VALUE, Long.MAX_VALUE is returned.
 	 */
-	static long calculateExpiry(long now, int maxLatency, int txCount) {
+	static long calculateExpiry(long now, long maxLatency, int txCount) {
 		if (now < 0) throw new IllegalArgumentException();
-		if (maxLatency <= 0) throw new IllegalArgumentException();
+		if (maxLatency <= 0 || maxLatency > MAX_TRANSPORT_LATENCY) {
+			throw new IllegalArgumentException();
+		}
 		if (txCount < 0) throw new IllegalArgumentException();
 		// The maximum round-trip time is twice the maximum latency
 		long roundTrip = maxLatency * 2L;

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

@@ -84,9 +84,14 @@ class H2Database extends JdbcDatabase {
 	@Override
 	public void close() throws DbException {
 		// H2 will close the database when the last connection closes
+		Connection c = null;
 		try {
+			c = createConnection();
 			super.closeAllConnections();
+			setDirty(c, false);
+			c.close();
 		} catch (SQLException e) {
+			tryToClose(c, LOG, WARNING);
 			throw new DbException(e);
 		}
 	}

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

@@ -81,6 +81,7 @@ class HyperSqlDatabase extends JdbcDatabase {
 		try {
 			super.closeAllConnections();
 			c = createConnection();
+			setDirty(c, false);
 			s = c.createStatement();
 			s.executeQuery("SHUTDOWN");
 			s.close();

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

@@ -51,6 +51,7 @@ 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;
@@ -72,6 +73,8 @@ import static java.util.Arrays.asList;
 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.sync.Group.Visibility.INVISIBLE;
 import static org.briarproject.bramble.api.sync.Group.Visibility.SHARED;
@@ -81,6 +84,7 @@ import static org.briarproject.bramble.api.sync.validation.MessageState.DELIVERE
 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;
@@ -98,7 +102,7 @@ import static org.briarproject.bramble.util.LogUtils.now;
 abstract class JdbcDatabase implements Database<Connection> {
 
 	// Package access for testing
-	static final int CODE_SCHEMA_VERSION = 47;
+	static final int CODE_SCHEMA_VERSION = 49;
 
 	// Time period offsets for incoming transport keys
 	private static final int OFFSET_PREV = -1;
@@ -180,6 +184,11 @@ abstract class JdbcDatabase implements Database<Connection> {
 					+ " state INT NOT NULL,"
 					+ " shared BOOLEAN NOT NULL,"
 					+ " temporary BOOLEAN NOT NULL,"
+					// Null if no timer duration has been set
+					+ " cleanupTimerDuration BIGINT,"
+					// Null if no timer duration has been set or the timer
+					// hasn't started
+					+ " cleanupDeadline BIGINT,"
 					+ " length INT NOT NULL,"
 					+ " raw BLOB," // Null if message has been deleted
 					+ " PRIMARY KEY (messageId),"
@@ -258,7 +267,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 	private static final String CREATE_TRANSPORTS =
 			"CREATE TABLE transports"
 					+ " (transportId _STRING NOT NULL,"
-					+ " maxLatency INT NOT NULL,"
+					+ " maxLatency BIGINT NOT NULL,"
 					+ " PRIMARY KEY (transportId))";
 
 	private static final String CREATE_PENDING_CONTACTS =
@@ -336,6 +345,15 @@ abstract class JdbcDatabase implements Database<Connection> {
 			"CREATE INDEX IF NOT EXISTS statusesByContactIdTimestamp"
 					+ " ON statuses (contactId, timestamp)";
 
+	private static final String
+			INDEX_STATUSES_BY_CONTACT_ID_TX_COUNT_TIMESTAMP =
+			"CREATE INDEX IF NOT EXISTS statusesByContactIdTxCountTimestamp"
+					+ " ON statuses (contactId, txCount, timestamp)";
+
+	private static final String INDEX_MESSAGES_BY_CLEANUP_DEADLINE =
+			"CREATE INDEX IF NOT EXISTS messagesByCleanupDeadline"
+					+ " ON messages (cleanupDeadline)";
+
 	private static final Logger LOG =
 			getLogger(JdbcDatabase.class.getName());
 
@@ -354,9 +372,14 @@ abstract class JdbcDatabase implements Database<Connection> {
 	@GuardedBy("connectionsLock")
 	private boolean closed = false;
 
+	private volatile boolean wasDirtyOnInitialisation = false;
+
 	protected abstract Connection createConnection()
 			throws DbException, SQLException;
 
+	// Used exclusively during open to compact the database after schema
+	// migrations or after DatabaseConstants#MAX_COMPACTION_INTERVAL_MS has
+	// elapsed
 	protected abstract void compactAndClose() throws DbException;
 
 	JdbcDatabase(DatabaseTypes databaseTypes, MessageFactory messageFactory,
@@ -381,13 +404,19 @@ abstract class JdbcDatabase implements Database<Connection> {
 		try {
 			if (reopen) {
 				Settings s = getSettings(txn, DB_SETTINGS_NAMESPACE);
+				wasDirtyOnInitialisation = isDirty(s);
 				compact = migrateSchema(txn, s, listener) || isCompactionDue(s);
 			} else {
+				wasDirtyOnInitialisation = false;
 				createTables(txn);
 				initialiseSettings(txn);
 				compact = false;
 			}
+			if (LOG.isLoggable(INFO)) {
+				LOG.info("db dirty? " + wasDirtyOnInitialisation);
+			}
 			createIndexes(txn);
+			setDirty(txn, true);
 			commitTransaction(txn);
 		} catch (DbException e) {
 			abortTransaction(txn);
@@ -414,6 +443,11 @@ abstract class JdbcDatabase implements Database<Connection> {
 		}
 	}
 
+	@Override
+	public boolean wasDirtyOnInitialisation() {
+		return wasDirtyOnInitialisation;
+	}
+
 	/**
 	 * Compares the schema version stored in the database with the schema
 	 * version used by the current code and applies any suitable migrations to
@@ -463,7 +497,9 @@ abstract class JdbcDatabase implements Database<Connection> {
 				new Migration43_44(dbTypes),
 				new Migration44_45(),
 				new Migration45_46(),
-				new Migration46_47(dbTypes)
+				new Migration46_47(dbTypes),
+				new Migration47_48(),
+				new Migration48_49()
 		);
 	}
 
@@ -488,6 +524,16 @@ abstract class JdbcDatabase implements Database<Connection> {
 		mergeSettings(txn, s, DB_SETTINGS_NAMESPACE);
 	}
 
+	private boolean isDirty(Settings s) {
+		return s.getBoolean(DIRTY_KEY, false);
+	}
+
+	protected void setDirty(Connection txn, boolean dirty) throws DbException {
+		Settings s = new Settings();
+		s.putBoolean(DIRTY_KEY, dirty);
+		mergeSettings(txn, s, DB_SETTINGS_NAMESPACE);
+	}
+
 	private void initialiseSettings(Connection txn) throws DbException {
 		Settings s = new Settings();
 		s.putInt(SCHEMA_VERSION_KEY, CODE_SCHEMA_VERSION);
@@ -531,6 +577,8 @@ abstract class JdbcDatabase implements Database<Connection> {
 			s.executeUpdate(INDEX_MESSAGE_DEPENDENCIES_BY_DEPENDENCY_ID);
 			s.executeUpdate(INDEX_STATUSES_BY_CONTACT_ID_GROUP_ID);
 			s.executeUpdate(INDEX_STATUSES_BY_CONTACT_ID_TIMESTAMP);
+			s.executeUpdate(INDEX_STATUSES_BY_CONTACT_ID_TX_COUNT_TIMESTAMP);
+			s.executeUpdate(INDEX_MESSAGES_BY_CLEANUP_DEADLINE);
 			s.close();
 		} catch (SQLException e) {
 			tryToClose(s, LOG, WARNING);
@@ -959,7 +1007,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 	}
 
 	@Override
-	public void addTransport(Connection txn, TransportId t, int maxLatency)
+	public void addTransport(Connection txn, TransportId t, long maxLatency)
 			throws DbException {
 		PreparedStatement ps = null;
 		try {
@@ -1080,6 +1128,55 @@ abstract class JdbcDatabase implements Database<Connection> {
 		}
 	}
 
+	@Override
+	public boolean containsAnythingToSend(Connection txn, ContactId c,
+			long maxLatency, boolean eager) throws DbException {
+		PreparedStatement ps = null;
+		ResultSet rs = null;
+		try {
+			String sql = "SELECT NULL FROM statuses"
+					+ " WHERE contactId = ? AND ack = TRUE";
+			ps = txn.prepareStatement(sql);
+			ps.setInt(1, c.getInt());
+			rs = ps.executeQuery();
+			boolean acksToSend = rs.next();
+			rs.close();
+			ps.close();
+			if (acksToSend) return true;
+			if (eager) {
+				sql = "SELECT NULL from statuses"
+						+ " 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());
+			} 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 > ?)";
+				ps = txn.prepareStatement(sql);
+				ps.setInt(1, c.getInt());
+				ps.setInt(2, DELIVERED.getValue());
+				ps.setLong(3, now);
+				ps.setLong(4, eta);
+			}
+			rs = ps.executeQuery();
+			boolean messagesToSend = rs.next();
+			rs.close();
+			ps.close();
+			return messagesToSend;
+		} catch (SQLException e) {
+			tryToClose(rs, LOG, WARNING);
+			tryToClose(ps, LOG, WARNING);
+			throw new DbException(e);
+		}
+	}
+
 	@Override
 	public boolean containsContact(Connection txn, AuthorId remote,
 			AuthorId local) throws DbException {
@@ -1237,6 +1334,29 @@ abstract class JdbcDatabase implements Database<Connection> {
 		}
 	}
 
+	@Override
+	public boolean containsTransportKeys(Connection txn, ContactId c,
+			TransportId t) throws DbException {
+		PreparedStatement ps = null;
+		ResultSet rs = null;
+		try {
+			String sql = "SELECT NULL FROM outgoingKeys"
+					+ " WHERE contactId = ? AND transportId = ?";
+			ps = txn.prepareStatement(sql);
+			ps.setInt(1, c.getInt());
+			ps.setString(2, t.getString());
+			rs = ps.executeQuery();
+			boolean found = rs.next();
+			rs.close();
+			ps.close();
+			return found;
+		} catch (SQLException e) {
+			tryToClose(rs, LOG, WARNING);
+			tryToClose(ps, LOG, WARNING);
+			throw new DbException(e);
+		}
+	}
+
 	@Override
 	public boolean containsVisibleMessage(Connection txn, ContactId c,
 			MessageId m) throws DbException {
@@ -1290,7 +1410,9 @@ abstract class JdbcDatabase implements Database<Connection> {
 	public void deleteMessage(Connection txn, MessageId m) throws DbException {
 		PreparedStatement ps = null;
 		try {
-			String sql = "UPDATE messages SET raw = NULL WHERE messageId = ?";
+			String sql = "UPDATE messages"
+					+ " SET raw = NULL, cleanupDeadline = NULL"
+					+ " WHERE messageId = ?";
 			ps = txn.prepareStatement(sql);
 			ps.setBytes(1, m.getBytes());
 			int affected = ps.executeUpdate();
@@ -1769,7 +1891,6 @@ abstract class JdbcDatabase implements Database<Connection> {
 				// Return early if there are no matches
 				if (intersection.isEmpty()) return Collections.emptySet();
 			}
-			if (intersection == null) throw new AssertionError();
 			return intersection;
 		} catch (SQLException e) {
 			tryToClose(rs, LOG, WARNING);
@@ -2068,7 +2189,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 
 	@Override
 	public Collection<MessageId> getMessagesToOffer(Connection txn,
-			ContactId c, int maxMessages, int maxLatency) throws DbException {
+			ContactId c, int maxMessages, long maxLatency) throws DbException {
 		long now = clock.currentTimeMillis();
 		long eta = now + maxLatency;
 		PreparedStatement ps = null;
@@ -2127,7 +2248,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 
 	@Override
 	public Collection<MessageId> getMessagesToSend(Connection txn, ContactId c,
-			int maxLength, int maxLatency) throws DbException {
+			int maxLength, long maxLatency) throws DbException {
 		long now = clock.currentTimeMillis();
 		long eta = now + maxLatency;
 		PreparedStatement ps = null;
@@ -2164,6 +2285,63 @@ abstract class JdbcDatabase implements Database<Connection> {
 		}
 	}
 
+	@Override
+	public Map<MessageId, Integer> getUnackedMessagesToSend(Connection txn,
+			ContactId c) throws DbException {
+		PreparedStatement ps = null;
+		ResultSet rs = null;
+		try {
+			String sql = "SELECT length, messageId FROM statuses"
+					+ " WHERE contactId = ? AND state = ?"
+					+ " AND groupShared = TRUE AND messageShared = TRUE"
+					+ " AND deleted = FALSE AND seen = FALSE"
+					+ " ORDER BY txCount, timestamp";
+			ps = txn.prepareStatement(sql);
+			ps.setInt(1, c.getInt());
+			ps.setInt(2, DELIVERED.getValue());
+			rs = ps.executeQuery();
+			Map<MessageId, Integer> results = new LinkedHashMap<>();
+			while (rs.next()) {
+				int length = rs.getInt(1);
+				MessageId id = new MessageId(rs.getBytes(2));
+				results.put(id, length);
+			}
+			rs.close();
+			ps.close();
+			return results;
+		} catch (SQLException e) {
+			tryToClose(rs, LOG, WARNING);
+			tryToClose(ps, LOG, WARNING);
+			throw new DbException(e);
+		}
+	}
+
+	@Override
+	public long getUnackedMessageBytesToSend(Connection txn, ContactId c)
+			throws DbException {
+		PreparedStatement ps = null;
+		ResultSet rs = null;
+		try {
+			String sql = "SELECT SUM(length) FROM statuses"
+					+ " 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());
+			rs = ps.executeQuery();
+			rs.next();
+			long total = rs.getLong(1);
+			rs.close();
+			ps.close();
+			return total;
+		} catch (SQLException e) {
+			tryToClose(rs, LOG, WARNING);
+			tryToClose(ps, LOG, WARNING);
+			throw new DbException(e);
+		}
+	}
+
 	@Override
 	public Collection<MessageId> getMessagesToValidate(Connection txn)
 			throws DbException {
@@ -2226,6 +2404,39 @@ abstract class JdbcDatabase implements Database<Connection> {
 		}
 	}
 
+	@Override
+	public Map<GroupId, Collection<MessageId>> getMessagesToDelete(
+			Connection txn) throws DbException {
+		long now = clock.currentTimeMillis();
+		PreparedStatement ps = null;
+		ResultSet rs = null;
+		try {
+			String sql = "SELECT messageId, groupId FROM messages"
+					+ " WHERE cleanupDeadline <= ?";
+			ps = txn.prepareStatement(sql);
+			ps.setLong(1, now);
+			rs = ps.executeQuery();
+			Map<GroupId, Collection<MessageId>> ids = new HashMap<>();
+			while (rs.next()) {
+				MessageId m = new MessageId(rs.getBytes(1));
+				GroupId g = new GroupId(rs.getBytes(2));
+				Collection<MessageId> messageIds = ids.get(g);
+				if (messageIds == null) {
+					messageIds = new ArrayList<>();
+					ids.put(g, messageIds);
+				}
+				messageIds.add(m);
+			}
+			rs.close();
+			ps.close();
+			return ids;
+		} catch (SQLException e) {
+			tryToClose(rs, LOG, WARNING);
+			tryToClose(ps, LOG, WARNING);
+			throw new DbException(e);
+		}
+	}
+
 	@Override
 	public long getNextSendTime(Connection txn, ContactId c)
 			throws DbException {
@@ -2256,6 +2467,31 @@ abstract class JdbcDatabase implements Database<Connection> {
 		}
 	}
 
+	@Override
+	public long getNextCleanupDeadline(Connection txn) throws DbException {
+		Statement s = null;
+		ResultSet rs = null;
+		try {
+			String sql = "SELECT cleanupDeadline FROM messages"
+					+ " WHERE cleanupDeadline IS NOT NULL"
+					+ " ORDER BY cleanupDeadline LIMIT 1";
+			s = txn.createStatement();
+			rs = s.executeQuery(sql);
+			long nextDeadline = NO_CLEANUP_DEADLINE;
+			if (rs.next()) {
+				nextDeadline = rs.getLong(1);
+				if (rs.next()) throw new AssertionError();
+			}
+			rs.close();
+			s.close();
+			return nextDeadline;
+		} catch (SQLException e) {
+			tryToClose(rs, LOG, WARNING);
+			tryToClose(s, LOG, WARNING);
+			throw new DbException(e);
+		}
+	}
+
 	@Override
 	public PendingContact getPendingContact(Connection txn, PendingContactId p)
 			throws DbException {
@@ -2311,7 +2547,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 
 	@Override
 	public Collection<MessageId> getRequestedMessagesToSend(Connection txn,
-			ContactId c, int maxLength, int maxLatency) throws DbException {
+			ContactId c, int maxLength, long maxLatency) throws DbException {
 		long now = clock.currentTimeMillis();
 		long eta = now + maxLatency;
 		PreparedStatement ps = null;
@@ -2475,6 +2711,38 @@ abstract class JdbcDatabase implements Database<Connection> {
 		}
 	}
 
+	@Override
+	public Map<ContactId, Collection<TransportId>> getTransportsWithKeys(
+			Connection txn) throws DbException {
+		Statement s = null;
+		ResultSet rs = null;
+		try {
+			String sql = "SELECT DISTINCT contactId, transportId"
+					+ " FROM outgoingKeys";
+			s = txn.createStatement();
+			rs = s.executeQuery(sql);
+			Map<ContactId, Collection<TransportId>> ids = new HashMap<>();
+			while (rs.next()) {
+				ContactId c = new ContactId(rs.getInt(1));
+				TransportId t = new TransportId(rs.getString(2));
+				Collection<TransportId> transportIds = ids.get(c);
+				if (transportIds == null) {
+					transportIds = new ArrayList<>();
+					ids.put(c, transportIds);
+				}
+				transportIds.add(t);
+			}
+			rs.close();
+			s.close();
+			return ids;
+		} catch (SQLException e) {
+			tryToClose(rs, LOG, WARNING);
+			tryToClose(s, LOG, WARNING);
+			tryToClose(s, LOG, WARNING);
+			throw new DbException(e);
+		}
+	}
+
 	@Override
 	public void incrementStreamCounter(Connection txn, TransportId t,
 			KeySetId k) throws DbException {
@@ -2776,7 +3044,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 	}
 
 	@Override
-	public void raiseSeenFlag(Connection txn, ContactId c, MessageId m)
+	public boolean raiseSeenFlag(Connection txn, ContactId c, MessageId m)
 			throws DbException {
 		PreparedStatement ps = null;
 		try {
@@ -2788,6 +3056,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 			int affected = ps.executeUpdate();
 			if (affected < 0 || affected > 1) throw new DbStateException();
 			ps.close();
+			return affected == 1;
 		} catch (SQLException e) {
 			tryToClose(ps, LOG, WARNING);
 			throw new DbException(e);
@@ -3021,6 +3290,25 @@ abstract class JdbcDatabase implements Database<Connection> {
 		}
 	}
 
+	@Override
+	public void setCleanupTimerDuration(Connection txn, MessageId m,
+			long duration) throws DbException {
+		PreparedStatement ps = null;
+		try {
+			String sql = "UPDATE messages SET cleanupTimerDuration = ?"
+					+ " WHERE messageId = ? AND cleanupTimerDuration IS NULL";
+			ps = txn.prepareStatement(sql);
+			ps.setLong(1, duration);
+			ps.setBytes(2, m.getBytes());
+			int affected = ps.executeUpdate();
+			if (affected < 0 || affected > 1) throw new DbStateException();
+			ps.close();
+		} catch (SQLException e) {
+			tryToClose(ps, LOG, WARNING);
+			throw new DbException(e);
+		}
+	}
+
 	@Override
 	public void setContactVerified(Connection txn, ContactId c)
 			throws DbException {
@@ -3128,22 +3416,24 @@ abstract class JdbcDatabase implements Database<Connection> {
 	}
 
 	@Override
-	public void setMessageShared(Connection txn, MessageId m)
+	public void setMessageShared(Connection txn, MessageId m, boolean shared)
 			throws DbException {
 		PreparedStatement ps = null;
 		try {
-			String sql = "UPDATE messages SET shared = TRUE"
+			String sql = "UPDATE messages SET shared = ?"
 					+ " WHERE messageId = ?";
 			ps = txn.prepareStatement(sql);
-			ps.setBytes(1, m.getBytes());
+			ps.setBoolean(1, shared);
+			ps.setBytes(2, m.getBytes());
 			int affected = ps.executeUpdate();
 			if (affected < 0 || affected > 1) throw new DbStateException();
 			ps.close();
 			// Update denormalised column in statuses
-			sql = "UPDATE statuses SET messageShared = TRUE"
+			sql = "UPDATE statuses SET messageShared = ?"
 					+ " WHERE messageId = ?";
 			ps = txn.prepareStatement(sql);
-			ps.setBytes(1, m.getBytes());
+			ps.setBoolean(1, shared);
+			ps.setBytes(2, m.getBytes());
 			affected = ps.executeUpdate();
 			if (affected < 0) throw new DbStateException();
 			ps.close();
@@ -3272,9 +3562,63 @@ abstract class JdbcDatabase implements Database<Connection> {
 		}
 	}
 
+	@Override
+	public long startCleanupTimer(Connection txn, MessageId m)
+			throws DbException {
+		long now = clock.currentTimeMillis();
+		PreparedStatement ps = null;
+		ResultSet rs = null;
+		try {
+			String sql = "UPDATE messages"
+					+ " SET cleanupDeadline = ? + cleanupTimerDuration"
+					+ " WHERE messageId = ?"
+					+ " AND cleanupTimerDuration IS NOT NULL"
+					+ " AND cleanupDeadline IS NULL";
+			ps = txn.prepareStatement(sql);
+			ps.setLong(1, now);
+			ps.setBytes(2, m.getBytes());
+			int affected = ps.executeUpdate();
+			if (affected < 0 || affected > 1) throw new DbStateException();
+			ps.close();
+			if (affected == 0) return TIMER_NOT_STARTED;
+			sql = "SELECT cleanupDeadline FROM messages WHERE messageId = ?";
+			ps = txn.prepareStatement(sql);
+			ps.setBytes(1, m.getBytes());
+			rs = ps.executeQuery();
+			if (!rs.next()) throw new DbStateException();
+			long deadline = rs.getLong(1);
+			if (rs.next()) throw new DbStateException();
+			rs.close();
+			ps.close();
+			return deadline;
+		} catch (SQLException e) {
+			tryToClose(rs, LOG, WARNING);
+			tryToClose(ps, LOG, WARNING);
+			throw new DbException(e);
+		}
+	}
+
+	@Override
+	public void stopCleanupTimer(Connection txn, MessageId m)
+			throws DbException {
+		PreparedStatement ps = null;
+		try {
+			String sql = "UPDATE messages SET cleanupDeadline = NULL"
+					+ " WHERE messageId = ?";
+			ps = txn.prepareStatement(sql);
+			ps.setBytes(1, m.getBytes());
+			int affected = ps.executeUpdate();
+			if (affected < 0 || affected > 1) throw new DbStateException();
+			ps.close();
+		} catch (SQLException e) {
+			tryToClose(ps, LOG, WARNING);
+			throw new DbException(e);
+		}
+	}
+
 	@Override
 	public void updateExpiryTimeAndEta(Connection txn, ContactId c, MessageId m,
-			int maxLatency) throws DbException {
+			long maxLatency) throws DbException {
 		PreparedStatement ps = null;
 		ResultSet rs = null;
 		try {

bramble-core/src/main/java/org/briarproject/bramble/db/Migration47_48.java

@@ -0,0 +1,47 @@
+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 Migration47_48 implements Migration<Connection> {
+
+	private static final Logger LOG = getLogger(Migration47_48.class.getName());
+
+	@Override
+	public int getStartVersion() {
+		return 47;
+	}
+
+	@Override
+	public int getEndVersion() {
+		return 48;
+	}
+
+	@Override
+	public void migrate(Connection txn) throws DbException {
+		Statement s = null;
+		try {
+			s = txn.createStatement();
+			// Null if no timer duration has been set
+			s.execute("ALTER TABLE messages"
+					+ " ADD COLUMN cleanupTimerDuration BIGINT");
+			// Null if no timer duration has been set or the timer
+			// hasn't started
+			s.execute("ALTER TABLE messages"
+					+ " ADD COLUMN cleanupDeadline BIGINT");
+			s.execute("CREATE INDEX IF NOT EXISTS messagesByCleanupDeadline"
+					+ " ON messages (cleanupDeadline)");
+		} catch (SQLException e) {
+			tryToClose(s, LOG, WARNING);
+			throw new DbException(e);
+		}
+	}
+}

bramble-core/src/main/java/org/briarproject/bramble/db/Migration48_49.java

@@ -0,0 +1,41 @@
+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 Migration48_49 implements Migration<Connection> {
+
+	private static final Logger LOG = getLogger(Migration48_49.class.getName());
+
+	@Override
+	public int getStartVersion() {
+		return 48;
+	}
+
+	@Override
+	public int getEndVersion() {
+		return 49;
+	}
+
+	@Override
+	public void migrate(Connection txn) throws DbException {
+		Statement s = null;
+		try {
+			s = txn.createStatement();
+			s.execute("ALTER TABLE transports"
+					+ " ALTER COLUMN maxLatency"
+					+ " SET DATA TYPE BIGINT");
+		} catch (SQLException e) {
+			tryToClose(s, LOG, WARNING);
+			throw new DbException(e);
+		}
+	}
+}

bramble-core/src/main/java/org/briarproject/bramble/identity/IdentityManagerImpl.java

@@ -118,11 +118,6 @@ class IdentityManagerImpl implements IdentityManager, OpenDatabaseHook {
 		return cached.getLocalAuthor();
 	}
 
-	@Override
-	public Identity getIdentity(Transaction txn) throws DbException {
-		return getCachedIdentity(txn);
-	}
-
 	@Override
 	public LocalAuthor getLocalAuthor(Transaction txn) throws DbException {
 		return getCachedIdentity(txn).getLocalAuthor();

bramble-core/src/main/java/org/briarproject/bramble/keyagreement/KeyAgreementTransport.java

@@ -34,12 +34,12 @@ class KeyAgreementTransport {
 			Logger.getLogger(KeyAgreementTransport.class.getName());
 
 	// Accept records with current protocol version, known record type
-	private static Predicate<Record> ACCEPT = r ->
+	private static final Predicate<Record> ACCEPT = r ->
 			r.getProtocolVersion() == PROTOCOL_VERSION &&
 					isKnownRecordType(r.getRecordType());
 
 	// Ignore records with current protocol version, unknown record type
-	private static Predicate<Record> IGNORE = r ->
+	private static final Predicate<Record> IGNORE = r ->
 			r.getProtocolVersion() == PROTOCOL_VERSION &&
 					!isKnownRecordType(r.getRecordType());
 

bramble-core/src/main/java/org/briarproject/bramble/lifecycle/LifecycleManagerImpl.java

@@ -12,6 +12,7 @@ import org.briarproject.bramble.api.lifecycle.Service;
 import org.briarproject.bramble.api.lifecycle.ServiceException;
 import org.briarproject.bramble.api.lifecycle.event.LifecycleEvent;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.system.Clock;
 
 import java.util.List;
 import java.util.concurrent.CopyOnWriteArrayList;
@@ -34,11 +35,14 @@ import static org.briarproject.bramble.api.lifecycle.LifecycleManager.LifecycleS
 import static org.briarproject.bramble.api.lifecycle.LifecycleManager.LifecycleState.STARTING_SERVICES;
 import static org.briarproject.bramble.api.lifecycle.LifecycleManager.LifecycleState.STOPPING;
 import static org.briarproject.bramble.api.lifecycle.LifecycleManager.StartResult.ALREADY_RUNNING;
+import static org.briarproject.bramble.api.lifecycle.LifecycleManager.StartResult.CLOCK_ERROR;
 import static org.briarproject.bramble.api.lifecycle.LifecycleManager.StartResult.DATA_TOO_NEW_ERROR;
 import static org.briarproject.bramble.api.lifecycle.LifecycleManager.StartResult.DATA_TOO_OLD_ERROR;
 import static org.briarproject.bramble.api.lifecycle.LifecycleManager.StartResult.DB_ERROR;
 import static org.briarproject.bramble.api.lifecycle.LifecycleManager.StartResult.SERVICE_ERROR;
 import static org.briarproject.bramble.api.lifecycle.LifecycleManager.StartResult.SUCCESS;
+import static org.briarproject.bramble.api.system.Clock.MAX_REASONABLE_TIME_MS;
+import static org.briarproject.bramble.api.system.Clock.MIN_REASONABLE_TIME_MS;
 import static org.briarproject.bramble.util.LogUtils.logDuration;
 import static org.briarproject.bramble.util.LogUtils.logException;
 import static org.briarproject.bramble.util.LogUtils.now;
@@ -52,6 +56,7 @@ class LifecycleManagerImpl implements LifecycleManager, MigrationListener {
 
 	private final DatabaseComponent db;
 	private final EventBus eventBus;
+	private final Clock clock;
 	private final List<Service> services;
 	private final List<OpenDatabaseHook> openDatabaseHooks;
 	private final List<ExecutorService> executors;
@@ -63,9 +68,11 @@ class LifecycleManagerImpl implements LifecycleManager, MigrationListener {
 	private volatile LifecycleState state = STARTING;
 
 	@Inject
-	LifecycleManagerImpl(DatabaseComponent db, EventBus eventBus) {
+	LifecycleManagerImpl(DatabaseComponent db, EventBus eventBus,
+			Clock clock) {
 		this.db = db;
 		this.eventBus = eventBus;
+		this.clock = clock;
 		services = new CopyOnWriteArrayList<>();
 		openDatabaseHooks = new CopyOnWriteArrayList<>();
 		executors = new CopyOnWriteArrayList<>();
@@ -99,6 +106,13 @@ class LifecycleManagerImpl implements LifecycleManager, MigrationListener {
 			LOG.info("Already starting or stopping");
 			return ALREADY_RUNNING;
 		}
+		long now = clock.currentTimeMillis();
+		if (now < MIN_REASONABLE_TIME_MS || now > MAX_REASONABLE_TIME_MS) {
+			if (LOG.isLoggable(WARNING)) {
+				LOG.warning("System clock is unreasonable: " + now);
+			}
+			return CLOCK_ERROR;
+		}
 		try {
 			LOG.info("Opening database");
 			long start = now();

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

@@ -0,0 +1,634 @@
+package org.briarproject.bramble.plugin.bluetooth;
+
+import org.briarproject.bramble.api.FormatException;
+import org.briarproject.bramble.api.Multiset;
+import org.briarproject.bramble.api.Pair;
+import org.briarproject.bramble.api.data.BdfList;
+import org.briarproject.bramble.api.event.Event;
+import org.briarproject.bramble.api.event.EventListener;
+import org.briarproject.bramble.api.keyagreement.KeyAgreementConnection;
+import org.briarproject.bramble.api.keyagreement.KeyAgreementListener;
+import org.briarproject.bramble.api.keyagreement.event.KeyAgreementListeningEvent;
+import org.briarproject.bramble.api.keyagreement.event.KeyAgreementStoppedListeningEvent;
+import org.briarproject.bramble.api.lifecycle.IoExecutor;
+import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
+import org.briarproject.bramble.api.plugin.Backoff;
+import org.briarproject.bramble.api.plugin.ConnectionHandler;
+import org.briarproject.bramble.api.plugin.PluginCallback;
+import org.briarproject.bramble.api.plugin.PluginException;
+import org.briarproject.bramble.api.plugin.TransportId;
+import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
+import org.briarproject.bramble.api.properties.TransportProperties;
+import org.briarproject.bramble.api.properties.event.RemoteTransportPropertiesUpdatedEvent;
+import org.briarproject.bramble.api.rendezvous.KeyMaterialSource;
+import org.briarproject.bramble.api.rendezvous.RendezvousEndpoint;
+import org.briarproject.bramble.api.settings.Settings;
+import org.briarproject.bramble.api.settings.event.SettingsUpdatedEvent;
+
+import java.io.IOException;
+import java.security.SecureRandom;
+import java.util.Collection;
+import java.util.UUID;
+import java.util.concurrent.Executor;
+import java.util.concurrent.Semaphore;
+import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.logging.Logger;
+
+import javax.annotation.Nullable;
+import javax.annotation.concurrent.GuardedBy;
+import javax.annotation.concurrent.ThreadSafe;
+
+import static java.util.logging.Level.INFO;
+import static java.util.logging.Level.WARNING;
+import static java.util.logging.Logger.getLogger;
+import static org.briarproject.bramble.api.keyagreement.KeyAgreementConstants.TRANSPORT_ID_BLUETOOTH;
+import static org.briarproject.bramble.api.plugin.BluetoothConstants.DEFAULT_PREF_ADDRESS_IS_REFLECTED;
+import static org.briarproject.bramble.api.plugin.BluetoothConstants.DEFAULT_PREF_EVER_CONNECTED;
+import static org.briarproject.bramble.api.plugin.BluetoothConstants.DEFAULT_PREF_PLUGIN_ENABLE;
+import static org.briarproject.bramble.api.plugin.BluetoothConstants.ID;
+import static org.briarproject.bramble.api.plugin.BluetoothConstants.PREF_ADDRESS_IS_REFLECTED;
+import static org.briarproject.bramble.api.plugin.BluetoothConstants.PREF_EVER_CONNECTED;
+import static org.briarproject.bramble.api.plugin.BluetoothConstants.PROP_ADDRESS;
+import static org.briarproject.bramble.api.plugin.BluetoothConstants.PROP_UUID;
+import static org.briarproject.bramble.api.plugin.BluetoothConstants.UUID_BYTES;
+import static org.briarproject.bramble.api.plugin.Plugin.State.ACTIVE;
+import static org.briarproject.bramble.api.plugin.Plugin.State.DISABLED;
+import static org.briarproject.bramble.api.plugin.Plugin.State.INACTIVE;
+import static org.briarproject.bramble.api.plugin.Plugin.State.STARTING_STOPPING;
+import static org.briarproject.bramble.api.properties.TransportPropertyConstants.REFLECTED_PROPERTY_PREFIX;
+import static org.briarproject.bramble.util.LogUtils.logException;
+import static org.briarproject.bramble.util.PrivacyUtils.scrubMacAddress;
+import static org.briarproject.bramble.util.StringUtils.isNullOrEmpty;
+import static org.briarproject.bramble.util.StringUtils.macToBytes;
+import static org.briarproject.bramble.util.StringUtils.macToString;
+
+@MethodsNotNullByDefault
+@ParametersNotNullByDefault
+abstract class AbstractBluetoothPlugin<S, SS> implements BluetoothPlugin,
+		EventListener {
+
+	private static final Logger LOG =
+			getLogger(AbstractBluetoothPlugin.class.getName());
+
+	private final BluetoothConnectionLimiter connectionLimiter;
+	final BluetoothConnectionFactory<S> connectionFactory;
+
+	private final Executor ioExecutor, wakefulIoExecutor;
+	private final SecureRandom secureRandom;
+	private final Backoff backoff;
+	private final PluginCallback callback;
+	private final long maxLatency;
+	private final int maxIdleTime;
+	private final AtomicBoolean used = new AtomicBoolean(false);
+	private final AtomicBoolean everConnected = new AtomicBoolean(false);
+
+	protected final PluginState state = new PluginState();
+	protected final Semaphore discoverSemaphore = new Semaphore(1);
+
+	private volatile String contactConnectionsUuid = null;
+
+	abstract void initialiseAdapter() throws IOException;
+
+	abstract boolean isAdapterEnabled();
+
+	/**
+	 * Returns the local Bluetooth address, or null if no valid address can
+	 * be found.
+	 */
+	@Nullable
+	abstract String getBluetoothAddress();
+
+	abstract SS openServerSocket(String uuid) throws IOException;
+
+	abstract void tryToClose(@Nullable SS ss);
+
+	abstract DuplexTransportConnection acceptConnection(SS ss)
+			throws IOException;
+
+	abstract boolean isValidAddress(String address);
+
+	abstract DuplexTransportConnection connectTo(String address, String uuid)
+			throws IOException;
+
+	@Nullable
+	abstract DuplexTransportConnection discoverAndConnect(String uuid);
+
+	AbstractBluetoothPlugin(BluetoothConnectionLimiter connectionLimiter,
+			BluetoothConnectionFactory<S> connectionFactory,
+			Executor ioExecutor,
+			Executor wakefulIoExecutor,
+			SecureRandom secureRandom,
+			Backoff backoff,
+			PluginCallback callback,
+			long maxLatency,
+			int maxIdleTime) {
+		this.connectionLimiter = connectionLimiter;
+		this.connectionFactory = connectionFactory;
+		this.ioExecutor = ioExecutor;
+		this.wakefulIoExecutor = wakefulIoExecutor;
+		this.secureRandom = secureRandom;
+		this.backoff = backoff;
+		this.callback = callback;
+		this.maxLatency = maxLatency;
+		this.maxIdleTime = maxIdleTime;
+	}
+
+	void onAdapterEnabled() {
+		LOG.info("Bluetooth enabled");
+		// We may not have been able to get the local address before
+		ioExecutor.execute(this::updateProperties);
+		if (getState() == INACTIVE) bind();
+	}
+
+	void onAdapterDisabled() {
+		LOG.info("Bluetooth disabled");
+		connectionLimiter.allConnectionsClosed();
+		// The server socket may not have been closed automatically
+		SS ss = state.clearServerSocket();
+		if (ss != null) {
+			LOG.info("Closing server socket");
+			tryToClose(ss);
+		}
+	}
+
+	@Override
+	public TransportId getId() {
+		return ID;
+	}
+
+	@Override
+	public long getMaxLatency() {
+		return maxLatency;
+	}
+
+	@Override
+	public int getMaxIdleTime() {
+		return maxIdleTime;
+	}
+
+	@Override
+	public void start() throws PluginException {
+		if (used.getAndSet(true)) throw new IllegalStateException();
+		Settings settings = callback.getSettings();
+		boolean enabledByUser = settings.getBoolean(PREF_PLUGIN_ENABLE,
+				DEFAULT_PREF_PLUGIN_ENABLE);
+		everConnected.set(settings.getBoolean(PREF_EVER_CONNECTED,
+				DEFAULT_PREF_EVER_CONNECTED));
+		state.setStarted(enabledByUser);
+		try {
+			initialiseAdapter();
+		} catch (IOException e) {
+			throw new PluginException(e);
+		}
+		updateProperties();
+		if (enabledByUser && isAdapterEnabled()) bind();
+	}
+
+	private void bind() {
+		ioExecutor.execute(() -> {
+			if (getState() != INACTIVE) return;
+			// Bind a server socket to accept connections from contacts
+			SS ss;
+			try {
+				ss = openServerSocket(contactConnectionsUuid);
+			} catch (IOException e) {
+				logException(LOG, WARNING, e);
+				return;
+			}
+			if (!state.setServerSocket(ss)) {
+				LOG.info("Closing redundant server socket");
+				tryToClose(ss);
+				return;
+			}
+			backoff.reset();
+			acceptContactConnections(ss);
+		});
+	}
+
+	private void updateProperties() {
+		TransportProperties p = callback.getLocalProperties();
+		String address = p.get(PROP_ADDRESS);
+		String uuid = p.get(PROP_UUID);
+		Settings s = callback.getSettings();
+		boolean isReflected = s.getBoolean(PREF_ADDRESS_IS_REFLECTED,
+				DEFAULT_PREF_ADDRESS_IS_REFLECTED);
+		boolean changed = false;
+		if (address == null || isReflected) {
+			address = getBluetoothAddress();
+			if (LOG.isLoggable(INFO)) {
+				LOG.info("Local address " + scrubMacAddress(address));
+			}
+			if (address == null) {
+				if (everConnected.get()) {
+					address = getReflectedAddress();
+					if (LOG.isLoggable(INFO)) {
+						LOG.info("Reflected address " +
+								scrubMacAddress(address));
+					}
+					if (address != null) {
+						changed = true;
+						isReflected = true;
+					}
+				}
+			} else {
+				changed = true;
+				isReflected = false;
+			}
+		}
+		if (uuid == null) {
+			byte[] random = new byte[UUID_BYTES];
+			secureRandom.nextBytes(random);
+			uuid = UUID.nameUUIDFromBytes(random).toString();
+			changed = true;
+		}
+		contactConnectionsUuid = uuid;
+		if (changed) {
+			p = new TransportProperties();
+			// If we previously used a reflected address and there's no longer
+			// a reflected address with enough votes to be used, we'll continue
+			// to use the old reflected address until there's a new winner
+			if (address != null) p.put(PROP_ADDRESS, address);
+			p.put(PROP_UUID, uuid);
+			callback.mergeLocalProperties(p);
+			s = new Settings();
+			s.putBoolean(PREF_ADDRESS_IS_REFLECTED, isReflected);
+			callback.mergeSettings(s);
+		}
+	}
+
+	@Nullable
+	private String getReflectedAddress() {
+		// Count the number of votes for each reflected address
+		String key = REFLECTED_PROPERTY_PREFIX + PROP_ADDRESS;
+		Multiset<String> votes = new Multiset<>();
+		for (TransportProperties p : callback.getRemoteProperties()) {
+			String address = p.get(key);
+			if (address != null && isValidAddress(address)) votes.add(address);
+		}
+		// If an address gets more than half of the votes, accept it
+		int total = votes.getTotal();
+		for (String address : votes.keySet()) {
+			if (votes.getCount(address) * 2 > total) return address;
+		}
+		return null;
+	}
+
+	private void acceptContactConnections(SS ss) {
+		while (true) {
+			DuplexTransportConnection conn;
+			try {
+				conn = acceptConnection(ss);
+			} catch (IOException e) {
+				// This is expected when the server socket is closed
+				LOG.info("Server socket closed");
+				state.clearServerSocket();
+				return;
+			}
+			LOG.info("Connection received");
+			connectionLimiter.connectionOpened(conn);
+			backoff.reset();
+			setEverConnected();
+			callback.handleConnection(conn);
+		}
+	}
+
+	private void setEverConnected() {
+		if (!everConnected.getAndSet(true)) {
+			ioExecutor.execute(() -> {
+				Settings s = new Settings();
+				s.putBoolean(PREF_EVER_CONNECTED, true);
+				callback.mergeSettings(s);
+				// Contacts may already have sent a reflected address
+				updateProperties();
+			});
+		}
+	}
+
+	@Override
+	public void stop() {
+		SS ss = state.setStopped();
+		tryToClose(ss);
+	}
+
+	@Override
+	public State getState() {
+		return state.getState();
+	}
+
+	@Override
+	public int getReasonsDisabled() {
+		return state.getReasonsDisabled();
+	}
+
+	@Override
+	public boolean shouldPoll() {
+		return true;
+	}
+
+	@Override
+	public int getPollingInterval() {
+		return backoff.getPollingInterval();
+	}
+
+	@Override
+	public void poll(Collection<Pair<TransportProperties, ConnectionHandler>>
+			properties) {
+		if (getState() != ACTIVE) return;
+		backoff.increment();
+		for (Pair<TransportProperties, ConnectionHandler> p : properties) {
+			connect(p.getFirst(), p.getSecond());
+		}
+	}
+
+	private void connect(TransportProperties p, ConnectionHandler h) {
+		String address = p.get(PROP_ADDRESS);
+		if (isNullOrEmpty(address)) return;
+		String uuid = p.get(PROP_UUID);
+		if (isNullOrEmpty(uuid)) return;
+		wakefulIoExecutor.execute(() -> {
+			DuplexTransportConnection d = createConnection(p);
+			if (d != null) {
+				backoff.reset();
+				setEverConnected();
+				h.handleConnection(d);
+			}
+		});
+	}
+
+	@Nullable
+	private DuplexTransportConnection connect(String address, String uuid) {
+		// Validate the address
+		if (!isValidAddress(address)) {
+			if (LOG.isLoggable(WARNING))
+				// Not scrubbing here to be able to figure out the problem
+				LOG.warning("Invalid address " + address);
+			return null;
+		}
+		// Validate the UUID
+		try {
+			//noinspection ResultOfMethodCallIgnored
+			UUID.fromString(uuid);
+		} catch (IllegalArgumentException e) {
+			if (LOG.isLoggable(WARNING)) LOG.warning("Invalid UUID " + uuid);
+			return null;
+		}
+		if (LOG.isLoggable(INFO))
+			LOG.info("Connecting to " + scrubMacAddress(address));
+		try {
+			DuplexTransportConnection conn = connectTo(address, uuid);
+			if (LOG.isLoggable(INFO))
+				LOG.info("Connected to " + scrubMacAddress(address));
+			return conn;
+		} catch (IOException e) {
+			if (LOG.isLoggable(INFO))
+				LOG.info("Could not connect to " + scrubMacAddress(address));
+			return null;
+		}
+	}
+
+	@Override
+	public DuplexTransportConnection createConnection(TransportProperties p) {
+		if (getState() != ACTIVE) return null;
+		if (!connectionLimiter.canOpenContactConnection()) return null;
+		String address = p.get(PROP_ADDRESS);
+		if (isNullOrEmpty(address)) return null;
+		String uuid = p.get(PROP_UUID);
+		if (isNullOrEmpty(uuid)) return null;
+		DuplexTransportConnection conn = connect(address, uuid);
+		if (conn != null) connectionLimiter.connectionOpened(conn);
+		return conn;
+	}
+
+	@Override
+	public boolean supportsKeyAgreement() {
+		return true;
+	}
+
+	@Override
+	public KeyAgreementListener createKeyAgreementListener(byte[] commitment) {
+		if (getState() != ACTIVE) return null;
+		// No truncation necessary because COMMIT_LENGTH = 16
+		String uuid = UUID.nameUUIDFromBytes(commitment).toString();
+		if (LOG.isLoggable(INFO)) LOG.info("Key agreement UUID " + uuid);
+		// Bind a server socket for receiving key agreement connections
+		SS ss;
+		try {
+			ss = openServerSocket(uuid);
+		} catch (IOException e) {
+			logException(LOG, WARNING, e);
+			return null;
+		}
+		if (getState() != ACTIVE) {
+			tryToClose(ss);
+			return null;
+		}
+		BdfList descriptor = new BdfList();
+		descriptor.add(TRANSPORT_ID_BLUETOOTH);
+		String address = getBluetoothAddress();
+		if (address != null) descriptor.add(macToBytes(address));
+		return new BluetoothKeyAgreementListener(descriptor, ss);
+	}
+
+	@Override
+	public DuplexTransportConnection createKeyAgreementConnection(
+			byte[] commitment, BdfList descriptor) {
+		if (getState() != ACTIVE) return null;
+		// No truncation necessary because COMMIT_LENGTH = 16
+		String uuid = UUID.nameUUIDFromBytes(commitment).toString();
+		DuplexTransportConnection conn;
+		if (descriptor.size() == 1) {
+			if (LOG.isLoggable(INFO)) {
+				LOG.info("Discovering address for key agreement UUID " +
+						uuid);
+			}
+			conn = discoverAndConnect(uuid);
+		} else {
+			String address;
+			try {
+				address = parseAddress(descriptor);
+			} catch (FormatException e) {
+				LOG.info("Invalid address in key agreement descriptor");
+				return null;
+			}
+			if (LOG.isLoggable(INFO))
+				LOG.info("Connecting to key agreement UUID " + uuid);
+			conn = connect(address, uuid);
+		}
+		if (conn != null) {
+			connectionLimiter.connectionOpened(conn);
+			setEverConnected();
+		}
+		return conn;
+	}
+
+	private String parseAddress(BdfList descriptor) throws FormatException {
+		byte[] mac = descriptor.getRaw(1);
+		if (mac.length != 6) throw new FormatException();
+		return macToString(mac);
+	}
+
+	@Override
+	public boolean isDiscovering() {
+		return discoverSemaphore.availablePermits() == 0;
+	}
+
+	@Override
+	public void disablePolling() {
+		connectionLimiter.startLimiting();
+	}
+
+	@Override
+	public void enablePolling() {
+		connectionLimiter.endLimiting();
+	}
+
+	@Override
+	public DuplexTransportConnection discoverAndConnectForSetup(String uuid) {
+		DuplexTransportConnection conn = discoverAndConnect(uuid);
+		if (conn != null) {
+			connectionLimiter.connectionOpened(conn);
+			setEverConnected();
+		}
+		return conn;
+	}
+
+	@Override
+	public boolean supportsRendezvous() {
+		return false;
+	}
+
+	@Override
+	public RendezvousEndpoint createRendezvousEndpoint(KeyMaterialSource k,
+			boolean alice, ConnectionHandler incoming) {
+		throw new UnsupportedOperationException();
+	}
+
+	@Override
+	public void eventOccurred(Event e) {
+		if (e instanceof SettingsUpdatedEvent) {
+			SettingsUpdatedEvent s = (SettingsUpdatedEvent) e;
+			if (s.getNamespace().equals(ID.getString()))
+				ioExecutor.execute(() -> onSettingsUpdated(s.getSettings()));
+		} else if (e instanceof KeyAgreementListeningEvent) {
+			connectionLimiter.startLimiting();
+		} else if (e instanceof KeyAgreementStoppedListeningEvent) {
+			connectionLimiter.endLimiting();
+		} else if (e instanceof RemoteTransportPropertiesUpdatedEvent) {
+			RemoteTransportPropertiesUpdatedEvent r =
+					(RemoteTransportPropertiesUpdatedEvent) e;
+			if (r.getTransportId().equals(ID)) {
+				ioExecutor.execute(this::updateProperties);
+			}
+		}
+	}
+
+	@IoExecutor
+	private void onSettingsUpdated(Settings settings) {
+		boolean enabledByUser = settings.getBoolean(PREF_PLUGIN_ENABLE,
+				DEFAULT_PREF_PLUGIN_ENABLE);
+		SS ss = state.setEnabledByUser(enabledByUser);
+		State s = getState();
+		if (ss != null) {
+			LOG.info("Disabled by user, closing server socket");
+			tryToClose(ss);
+		} else if (s == INACTIVE) {
+			if (isAdapterEnabled()) {
+				LOG.info("Enabled by user, opening server socket");
+				bind();
+			} else {
+				LOG.info("Enabled by user but adapter is disabled");
+			}
+		}
+	}
+
+	private class BluetoothKeyAgreementListener extends KeyAgreementListener {
+
+		private final SS ss;
+
+		private BluetoothKeyAgreementListener(BdfList descriptor, SS ss) {
+			super(descriptor);
+			this.ss = ss;
+		}
+
+		@Override
+		public KeyAgreementConnection accept() throws IOException {
+			DuplexTransportConnection conn = acceptConnection(ss);
+			if (LOG.isLoggable(INFO)) LOG.info(ID + ": Incoming connection");
+			connectionLimiter.connectionOpened(conn);
+			return new KeyAgreementConnection(conn, ID);
+		}
+
+		@Override
+		public void close() {
+			tryToClose(ss);
+		}
+	}
+
+	@ThreadSafe
+	@NotNullByDefault
+	private class PluginState {
+
+		@GuardedBy("this")
+		private boolean started = false,
+				stopped = false,
+				enabledByUser = false;
+
+		@GuardedBy("this")
+		@Nullable
+		private SS serverSocket = null;
+
+		private synchronized void setStarted(boolean enabledByUser) {
+			started = true;
+			this.enabledByUser = enabledByUser;
+			callback.pluginStateChanged(getState());
+		}
+
+		@Nullable
+		private synchronized SS setStopped() {
+			stopped = true;
+			SS ss = serverSocket;
+			serverSocket = null;
+			callback.pluginStateChanged(getState());
+			return ss;
+		}
+
+		@Nullable
+		private synchronized SS setEnabledByUser(boolean enabledByUser) {
+			this.enabledByUser = enabledByUser;
+			SS ss = null;
+			if (!enabledByUser) {
+				ss = serverSocket;
+				serverSocket = null;
+			}
+			callback.pluginStateChanged(getState());
+			return ss;
+		}
+
+		private synchronized boolean setServerSocket(SS ss) {
+			if (stopped || serverSocket != null) return false;
+			serverSocket = ss;
+			callback.pluginStateChanged(getState());
+			return true;
+		}
+
+		@Nullable
+		private synchronized SS clearServerSocket() {
+			SS ss = serverSocket;
+			serverSocket = null;
+			callback.pluginStateChanged(getState());
+			return ss;
+		}
+
+		private synchronized State getState() {
+			if (!started || stopped) return STARTING_STOPPING;
+			if (!enabledByUser) return DISABLED;
+			return serverSocket == null ? INACTIVE : ACTIVE;
+		}
+
+		private synchronized int getReasonsDisabled() {
+			return getState() == DISABLED ? REASON_USER : 0;
+		}
+	}
+}

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

@@ -7,14 +7,15 @@ import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
 interface BluetoothConnectionLimiter {
 
 	/**
-	 * Informs the limiter that key agreement has started.
+	 * Tells the limiter to not allow regular polling connections (because we
+	 * are about to do key agreement, or connect via BT for setup).
 	 */
-	void keyAgreementStarted();
+	void startLimiting();
 
 	/**
-	 * Informs the limiter that key agreement has ended.
+	 * Tells the limiter to no longer limit regular polling connections.
 	 */
-	void keyAgreementEnded();
+	void endLimiting();
 
 	/**
 	 * Returns true if a contact connection can be opened. This method does not

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

@@ -30,34 +30,37 @@ class BluetoothConnectionLimiterImpl implements BluetoothConnectionLimiter {
 	private final List<DuplexTransportConnection> connections =
 			new LinkedList<>();
 	@GuardedBy("lock")
-	private boolean keyAgreementInProgress = false;
+	private int limitingInProgress = 0;
 
 	BluetoothConnectionLimiterImpl(EventBus eventBus) {
 		this.eventBus = eventBus;
 	}
 
 	@Override
-	public void keyAgreementStarted() {
+	public void startLimiting() {
 		synchronized (lock) {
-			keyAgreementInProgress = true;
+			limitingInProgress++;
 		}
-		LOG.info("Key agreement started");
+		LOG.info("Limiting started");
 		eventBus.broadcast(new CloseSyncConnectionsEvent(ID));
 	}
 
 	@Override
-	public void keyAgreementEnded() {
+	public void endLimiting() {
 		synchronized (lock) {
-			keyAgreementInProgress = false;
+			limitingInProgress--;
+			if (limitingInProgress < 0) {
+				throw new IllegalStateException();
+			}
 		}
-		LOG.info("Key agreement ended");
+		LOG.info("Limiting ended");
 	}
 
 	@Override
 	public boolean canOpenContactConnection() {
 		synchronized (lock) {
-			if (keyAgreementInProgress) {
-				LOG.info("Can't open contact connection during key agreement");
+			if (limitingInProgress > 0) {
+				LOG.info("Can't open contact connection while limiting");
 				return false;
 			} else {
 				LOG.info("Can open contact connection");

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

@@ -1,606 +1,22 @@
 package org.briarproject.bramble.plugin.bluetooth;
 
-import org.briarproject.bramble.api.FormatException;
-import org.briarproject.bramble.api.Multiset;
-import org.briarproject.bramble.api.Pair;
-import org.briarproject.bramble.api.data.BdfList;
-import org.briarproject.bramble.api.event.Event;
-import org.briarproject.bramble.api.event.EventListener;
-import org.briarproject.bramble.api.keyagreement.KeyAgreementConnection;
-import org.briarproject.bramble.api.keyagreement.KeyAgreementListener;
-import org.briarproject.bramble.api.keyagreement.event.KeyAgreementListeningEvent;
-import org.briarproject.bramble.api.keyagreement.event.KeyAgreementStoppedListeningEvent;
-import org.briarproject.bramble.api.lifecycle.IoExecutor;
-import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
-import org.briarproject.bramble.api.plugin.Backoff;
-import org.briarproject.bramble.api.plugin.ConnectionHandler;
-import org.briarproject.bramble.api.plugin.PluginCallback;
-import org.briarproject.bramble.api.plugin.PluginException;
-import org.briarproject.bramble.api.plugin.TransportId;
 import org.briarproject.bramble.api.plugin.duplex.DuplexPlugin;
 import org.briarproject.bramble.api.plugin.duplex.DuplexTransportConnection;
-import org.briarproject.bramble.api.properties.TransportProperties;
-import org.briarproject.bramble.api.properties.event.RemoteTransportPropertiesUpdatedEvent;
-import org.briarproject.bramble.api.rendezvous.KeyMaterialSource;
-import org.briarproject.bramble.api.rendezvous.RendezvousEndpoint;
-import org.briarproject.bramble.api.settings.Settings;
-import org.briarproject.bramble.api.settings.event.SettingsUpdatedEvent;
-
-import java.io.IOException;
-import java.security.SecureRandom;
-import java.util.Collection;
-import java.util.UUID;
-import java.util.concurrent.Executor;
-import java.util.concurrent.atomic.AtomicBoolean;
-import java.util.logging.Logger;
 
 import javax.annotation.Nullable;
-import javax.annotation.concurrent.GuardedBy;
-import javax.annotation.concurrent.ThreadSafe;
 
-import static java.util.logging.Level.INFO;
-import static java.util.logging.Level.WARNING;
-import static java.util.logging.Logger.getLogger;
-import static org.briarproject.bramble.api.keyagreement.KeyAgreementConstants.TRANSPORT_ID_BLUETOOTH;
-import static org.briarproject.bramble.api.plugin.BluetoothConstants.DEFAULT_PREF_ADDRESS_IS_REFLECTED;
-import static org.briarproject.bramble.api.plugin.BluetoothConstants.DEFAULT_PREF_EVER_CONNECTED;
-import static org.briarproject.bramble.api.plugin.BluetoothConstants.DEFAULT_PREF_PLUGIN_ENABLE;
-import static org.briarproject.bramble.api.plugin.BluetoothConstants.ID;
-import static org.briarproject.bramble.api.plugin.BluetoothConstants.PREF_ADDRESS_IS_REFLECTED;
-import static org.briarproject.bramble.api.plugin.BluetoothConstants.PREF_EVER_CONNECTED;
-import static org.briarproject.bramble.api.plugin.BluetoothConstants.PROP_ADDRESS;
-import static org.briarproject.bramble.api.plugin.BluetoothConstants.PROP_UUID;
-import static org.briarproject.bramble.api.plugin.BluetoothConstants.UUID_BYTES;
-import static org.briarproject.bramble.api.plugin.Plugin.State.ACTIVE;
-import static org.briarproject.bramble.api.plugin.Plugin.State.DISABLED;
-import static org.briarproject.bramble.api.plugin.Plugin.State.INACTIVE;
-import static org.briarproject.bramble.api.plugin.Plugin.State.STARTING_STOPPING;
-import static org.briarproject.bramble.api.properties.TransportPropertyConstants.REFLECTED_PROPERTY_PREFIX;
-import static org.briarproject.bramble.util.LogUtils.logException;
-import static org.briarproject.bramble.util.PrivacyUtils.scrubMacAddress;
-import static org.briarproject.bramble.util.StringUtils.isNullOrEmpty;
-import static org.briarproject.bramble.util.StringUtils.macToBytes;
-import static org.briarproject.bramble.util.StringUtils.macToString;
+@NotNullByDefault
+public interface BluetoothPlugin extends DuplexPlugin {
 
-@MethodsNotNullByDefault
-@ParametersNotNullByDefault
-abstract class BluetoothPlugin<S, SS> implements DuplexPlugin, EventListener {
+	boolean isDiscovering();
 
-	private static final Logger LOG =
-			getLogger(BluetoothPlugin.class.getName());
+	void disablePolling();
 
-	final BluetoothConnectionLimiter connectionLimiter;
-	final BluetoothConnectionFactory<S> connectionFactory;
-
-	private final Executor ioExecutor, wakefulIoExecutor;
-	private final SecureRandom secureRandom;
-	private final Backoff backoff;
-	private final PluginCallback callback;
-	private final int maxLatency, maxIdleTime;
-	private final AtomicBoolean used = new AtomicBoolean(false);
-	private final AtomicBoolean everConnected = new AtomicBoolean(false);
-
-	protected final PluginState state = new PluginState();
-
-	private volatile String contactConnectionsUuid = null;
-
-	abstract void initialiseAdapter() throws IOException;
-
-	abstract boolean isAdapterEnabled();
-
-	/**
-	 * Returns the local Bluetooth address, or null if no valid address can
-	 * be found.
-	 */
-	@Nullable
-	abstract String getBluetoothAddress();
-
-	abstract SS openServerSocket(String uuid) throws IOException;
-
-	abstract void tryToClose(@Nullable SS ss);
-
-	abstract DuplexTransportConnection acceptConnection(SS ss)
-			throws IOException;
-
-	abstract boolean isValidAddress(String address);
-
-	abstract DuplexTransportConnection connectTo(String address, String uuid)
-			throws IOException;
+	void enablePolling();
 
 	@Nullable
-	abstract DuplexTransportConnection discoverAndConnect(String uuid);
+	DuplexTransportConnection discoverAndConnectForSetup(String uuid);
 
-	BluetoothPlugin(BluetoothConnectionLimiter connectionLimiter,
-			BluetoothConnectionFactory<S> connectionFactory,
-			Executor ioExecutor,
-			Executor wakefulIoExecutor,
-			SecureRandom secureRandom,
-			Backoff backoff,
-			PluginCallback callback,
-			int maxLatency,
-			int maxIdleTime) {
-		this.connectionLimiter = connectionLimiter;
-		this.connectionFactory = connectionFactory;
-		this.ioExecutor = ioExecutor;
-		this.wakefulIoExecutor = wakefulIoExecutor;
-		this.secureRandom = secureRandom;
-		this.backoff = backoff;
-		this.callback = callback;
-		this.maxLatency = maxLatency;
-		this.maxIdleTime = maxIdleTime;
-	}
-
-	void onAdapterEnabled() {
-		LOG.info("Bluetooth enabled");
-		// We may not have been able to get the local address before
-		ioExecutor.execute(this::updateProperties);
-		if (getState() == INACTIVE) bind();
-	}
-
-	void onAdapterDisabled() {
-		LOG.info("Bluetooth disabled");
-		connectionLimiter.allConnectionsClosed();
-		// The server socket may not have been closed automatically
-		SS ss = state.clearServerSocket();
-		if (ss != null) {
-			LOG.info("Closing server socket");
-			tryToClose(ss);
-		}
-	}
-
-	@Override
-	public TransportId getId() {
-		return ID;
-	}
-
-	@Override
-	public int getMaxLatency() {
-		return maxLatency;
-	}
-
-	@Override
-	public int getMaxIdleTime() {
-		return maxIdleTime;
-	}
-
-	@Override
-	public void start() throws PluginException {
-		if (used.getAndSet(true)) throw new IllegalStateException();
-		Settings settings = callback.getSettings();
-		boolean enabledByUser = settings.getBoolean(PREF_PLUGIN_ENABLE,
-				DEFAULT_PREF_PLUGIN_ENABLE);
-		everConnected.set(settings.getBoolean(PREF_EVER_CONNECTED,
-				DEFAULT_PREF_EVER_CONNECTED));
-		state.setStarted(enabledByUser);
-		try {
-			initialiseAdapter();
-		} catch (IOException e) {
-			throw new PluginException(e);
-		}
-		updateProperties();
-		if (enabledByUser && isAdapterEnabled()) bind();
-	}
-
-	private void bind() {
-		ioExecutor.execute(() -> {
-			if (getState() != INACTIVE) return;
-			// Bind a server socket to accept connections from contacts
-			SS ss;
-			try {
-				ss = openServerSocket(contactConnectionsUuid);
-			} catch (IOException e) {
-				logException(LOG, WARNING, e);
-				return;
-			}
-			if (!state.setServerSocket(ss)) {
-				LOG.info("Closing redundant server socket");
-				tryToClose(ss);
-				return;
-			}
-			backoff.reset();
-			acceptContactConnections(ss);
-		});
-	}
-
-	private void updateProperties() {
-		TransportProperties p = callback.getLocalProperties();
-		String address = p.get(PROP_ADDRESS);
-		String uuid = p.get(PROP_UUID);
-		Settings s = callback.getSettings();
-		boolean isReflected = s.getBoolean(PREF_ADDRESS_IS_REFLECTED,
-				DEFAULT_PREF_ADDRESS_IS_REFLECTED);
-		boolean changed = false;
-		if (address == null || isReflected) {
-			address = getBluetoothAddress();
-			if (LOG.isLoggable(INFO)) {
-				LOG.info("Local address " + scrubMacAddress(address));
-			}
-			if (address == null) {
-				if (everConnected.get()) {
-					address = getReflectedAddress();
-					if (LOG.isLoggable(INFO)) {
-						LOG.info("Reflected address " +
-								scrubMacAddress(address));
-					}
-					if (address != null) {
-						changed = true;
-						isReflected = true;
-					}
-				}
-			} else {
-				changed = true;
-				isReflected = false;
-			}
-		}
-		if (uuid == null) {
-			byte[] random = new byte[UUID_BYTES];
-			secureRandom.nextBytes(random);
-			uuid = UUID.nameUUIDFromBytes(random).toString();
-			changed = true;
-		}
-		contactConnectionsUuid = uuid;
-		if (changed) {
-			p = new TransportProperties();
-			// If we previously used a reflected address and there's no longer
-			// a reflected address with enough votes to be used, we'll continue
-			// to use the old reflected address until there's a new winner
-			if (address != null) p.put(PROP_ADDRESS, address);
-			p.put(PROP_UUID, uuid);
-			callback.mergeLocalProperties(p);
-			s = new Settings();
-			s.putBoolean(PREF_ADDRESS_IS_REFLECTED, isReflected);
-			callback.mergeSettings(s);
-		}
-	}
-
-	@Nullable
-	private String getReflectedAddress() {
-		// Count the number of votes for each reflected address
-		String key = REFLECTED_PROPERTY_PREFIX + PROP_ADDRESS;
-		Multiset<String> votes = new Multiset<>();
-		for (TransportProperties p : callback.getRemoteProperties()) {
-			String address = p.get(key);
-			if (address != null && isValidAddress(address)) votes.add(address);
-		}
-		// If an address gets more than half of the votes, accept it
-		int total = votes.getTotal();
-		for (String address : votes.keySet()) {
-			if (votes.getCount(address) * 2 > total) return address;
-		}
-		return null;
-	}
-
-	private void acceptContactConnections(SS ss) {
-		while (true) {
-			DuplexTransportConnection conn;
-			try {
-				conn = acceptConnection(ss);
-			} catch (IOException e) {
-				// This is expected when the server socket is closed
-				LOG.info("Server socket closed");
-				state.clearServerSocket();
-				return;
-			}
-			LOG.info("Connection received");
-			connectionLimiter.connectionOpened(conn);
-			backoff.reset();
-			setEverConnected();
-			callback.handleConnection(conn);
-		}
-	}
-
-	private void setEverConnected() {
-		if (!everConnected.getAndSet(true)) {
-			ioExecutor.execute(() -> {
-				Settings s = new Settings();
-				s.putBoolean(PREF_EVER_CONNECTED, true);
-				callback.mergeSettings(s);
-				// Contacts may already have sent a reflected address
-				updateProperties();
-			});
-		}
-	}
-
-	@Override
-	public void stop() {
-		SS ss = state.setStopped();
-		tryToClose(ss);
-	}
-
-	@Override
-	public State getState() {
-		return state.getState();
-	}
-
-	@Override
-	public int getReasonsDisabled() {
-		return state.getReasonsDisabled();
-	}
-
-	@Override
-	public boolean shouldPoll() {
-		return true;
-	}
-
-	@Override
-	public int getPollingInterval() {
-		return backoff.getPollingInterval();
-	}
-
-	@Override
-	public void poll(Collection<Pair<TransportProperties, ConnectionHandler>>
-			properties) {
-		if (getState() != ACTIVE) return;
-		backoff.increment();
-		for (Pair<TransportProperties, ConnectionHandler> p : properties) {
-			connect(p.getFirst(), p.getSecond());
-		}
-	}
-
-	private void connect(TransportProperties p, ConnectionHandler h) {
-		String address = p.get(PROP_ADDRESS);
-		if (isNullOrEmpty(address)) return;
-		String uuid = p.get(PROP_UUID);
-		if (isNullOrEmpty(uuid)) return;
-		wakefulIoExecutor.execute(() -> {
-			DuplexTransportConnection d = createConnection(p);
-			if (d != null) {
-				backoff.reset();
-				setEverConnected();
-				h.handleConnection(d);
-			}
-		});
-	}
-
-	@Nullable
-	private DuplexTransportConnection connect(String address, String uuid) {
-		// Validate the address
-		if (!isValidAddress(address)) {
-			if (LOG.isLoggable(WARNING))
-				// Not scrubbing here to be able to figure out the problem
-				LOG.warning("Invalid address " + address);
-			return null;
-		}
-		// Validate the UUID
-		try {
-			//noinspection ResultOfMethodCallIgnored
-			UUID.fromString(uuid);
-		} catch (IllegalArgumentException e) {
-			if (LOG.isLoggable(WARNING)) LOG.warning("Invalid UUID " + uuid);
-			return null;
-		}
-		if (LOG.isLoggable(INFO))
-			LOG.info("Connecting to " + scrubMacAddress(address));
-		try {
-			DuplexTransportConnection conn = connectTo(address, uuid);
-			if (LOG.isLoggable(INFO))
-				LOG.info("Connected to " + scrubMacAddress(address));
-			return conn;
-		} catch (IOException e) {
-			if (LOG.isLoggable(INFO))
-				LOG.info("Could not connect to " + scrubMacAddress(address));
-			return null;
-		}
-	}
-
-	@Override
-	public DuplexTransportConnection createConnection(TransportProperties p) {
-		if (getState() != ACTIVE) return null;
-		if (!connectionLimiter.canOpenContactConnection()) return null;
-		String address = p.get(PROP_ADDRESS);
-		if (isNullOrEmpty(address)) return null;
-		String uuid = p.get(PROP_UUID);
-		if (isNullOrEmpty(uuid)) return null;
-		DuplexTransportConnection conn = connect(address, uuid);
-		if (conn != null) connectionLimiter.connectionOpened(conn);
-		return conn;
-	}
-
-	@Override
-	public boolean supportsKeyAgreement() {
-		return true;
-	}
-
-	@Override
-	public KeyAgreementListener createKeyAgreementListener(byte[] commitment) {
-		if (getState() != ACTIVE) return null;
-		// No truncation necessary because COMMIT_LENGTH = 16
-		String uuid = UUID.nameUUIDFromBytes(commitment).toString();
-		if (LOG.isLoggable(INFO)) LOG.info("Key agreement UUID " + uuid);
-		// Bind a server socket for receiving key agreement connections
-		SS ss;
-		try {
-			ss = openServerSocket(uuid);
-		} catch (IOException e) {
-			logException(LOG, WARNING, e);
-			return null;
-		}
-		if (getState() != ACTIVE) {
-			tryToClose(ss);
-			return null;
-		}
-		BdfList descriptor = new BdfList();
-		descriptor.add(TRANSPORT_ID_BLUETOOTH);
-		String address = getBluetoothAddress();
-		if (address != null) descriptor.add(macToBytes(address));
-		return new BluetoothKeyAgreementListener(descriptor, ss);
-	}
-
-	@Override
-	public DuplexTransportConnection createKeyAgreementConnection(
-			byte[] commitment, BdfList descriptor) {
-		if (getState() != ACTIVE) return null;
-		// No truncation necessary because COMMIT_LENGTH = 16
-		String uuid = UUID.nameUUIDFromBytes(commitment).toString();
-		DuplexTransportConnection conn;
-		if (descriptor.size() == 1) {
-			if (LOG.isLoggable(INFO)) {
-				LOG.info("Discovering address for key agreement UUID " +
-						uuid);
-			}
-			conn = discoverAndConnect(uuid);
-		} else {
-			String address;
-			try {
-				address = parseAddress(descriptor);
-			} catch (FormatException e) {
-				LOG.info("Invalid address in key agreement descriptor");
-				return null;
-			}
-			if (LOG.isLoggable(INFO))
-				LOG.info("Connecting to key agreement UUID " + uuid);
-			conn = connect(address, uuid);
-		}
-		if (conn != null) {
-			connectionLimiter.connectionOpened(conn);
-			setEverConnected();
-		}
-		return conn;
-	}
-
-	private String parseAddress(BdfList descriptor) throws FormatException {
-		byte[] mac = descriptor.getRaw(1);
-		if (mac.length != 6) throw new FormatException();
-		return macToString(mac);
-	}
-
-	@Override
-	public boolean supportsRendezvous() {
-		return false;
-	}
-
-	@Override
-	public RendezvousEndpoint createRendezvousEndpoint(KeyMaterialSource k,
-			boolean alice, ConnectionHandler incoming) {
-		throw new UnsupportedOperationException();
-	}
-
-	@Override
-	public void eventOccurred(Event e) {
-		if (e instanceof SettingsUpdatedEvent) {
-			SettingsUpdatedEvent s = (SettingsUpdatedEvent) e;
-			if (s.getNamespace().equals(ID.getString()))
-				ioExecutor.execute(() -> onSettingsUpdated(s.getSettings()));
-		} else if (e instanceof KeyAgreementListeningEvent) {
-			ioExecutor.execute(connectionLimiter::keyAgreementStarted);
-		} else if (e instanceof KeyAgreementStoppedListeningEvent) {
-			ioExecutor.execute(connectionLimiter::keyAgreementEnded);
-		} else if (e instanceof RemoteTransportPropertiesUpdatedEvent) {
-			RemoteTransportPropertiesUpdatedEvent r =
-					(RemoteTransportPropertiesUpdatedEvent) e;
-			if (r.getTransportId().equals(ID)) {
-				ioExecutor.execute(this::updateProperties);
-			}
-		}
-	}
-
-	@IoExecutor
-	private void onSettingsUpdated(Settings settings) {
-		boolean enabledByUser = settings.getBoolean(PREF_PLUGIN_ENABLE,
-				DEFAULT_PREF_PLUGIN_ENABLE);
-		SS ss = state.setEnabledByUser(enabledByUser);
-		State s = getState();
-		if (ss != null) {
-			LOG.info("Disabled by user, closing server socket");
-			tryToClose(ss);
-		} else if (s == INACTIVE) {
-			if (isAdapterEnabled()) {
-				LOG.info("Enabled by user, opening server socket");
-				bind();
-			} else {
-				LOG.info("Enabled by user but adapter is disabled");
-			}
-		}
-	}
-
-	private class BluetoothKeyAgreementListener extends KeyAgreementListener {
-
-		private final SS ss;
-
-		private BluetoothKeyAgreementListener(BdfList descriptor, SS ss) {
-			super(descriptor);
-			this.ss = ss;
-		}
-
-		@Override
-		public KeyAgreementConnection accept() throws IOException {
-			DuplexTransportConnection conn = acceptConnection(ss);
-			if (LOG.isLoggable(INFO)) LOG.info(ID + ": Incoming connection");
-			connectionLimiter.connectionOpened(conn);
-			return new KeyAgreementConnection(conn, ID);
-		}
-
-		@Override
-		public void close() {
-			tryToClose(ss);
-		}
-	}
-
-	@ThreadSafe
-	@NotNullByDefault
-	protected class PluginState {
-
-		@GuardedBy("this")
-		private boolean started = false,
-				stopped = false,
-				enabledByUser = false;
-
-		@GuardedBy("this")
-		@Nullable
-		private SS serverSocket = null;
-
-		synchronized void setStarted(boolean enabledByUser) {
-			started = true;
-			this.enabledByUser = enabledByUser;
-			callback.pluginStateChanged(getState());
-		}
-
-		@Nullable
-		synchronized SS setStopped() {
-			stopped = true;
-			SS ss = serverSocket;
-			serverSocket = null;
-			callback.pluginStateChanged(getState());
-			return ss;
-		}
-
-		@Nullable
-		synchronized SS setEnabledByUser(boolean enabledByUser) {
-			this.enabledByUser = enabledByUser;
-			SS ss = null;
-			if (!enabledByUser) {
-				ss = serverSocket;
-				serverSocket = null;
-			}
-			callback.pluginStateChanged(getState());
-			return ss;
-		}
-
-		synchronized boolean setServerSocket(SS ss) {
-			if (stopped || serverSocket != null) return false;
-			serverSocket = ss;
-			callback.pluginStateChanged(getState());
-			return true;
-		}
-
-		@Nullable
-		synchronized SS clearServerSocket() {
-			SS ss = serverSocket;
-			serverSocket = null;
-			callback.pluginStateChanged(getState());
-			return ss;
-		}
-
-		synchronized State getState() {
-			if (!started || stopped) return STARTING_STOPPING;
-			if (!enabledByUser) return DISABLED;
-			return serverSocket == null ? INACTIVE : ACTIVE;
-		}
-
-		synchronized int getReasonsDisabled() {
-			return getState() == DISABLED ? REASON_USER : 0;
-		}
-	}
+	void stopDiscoverAndConnect();
 }

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

@@ -0,0 +1,126 @@
+package org.briarproject.bramble.plugin.file;
+
+import org.briarproject.bramble.api.Pair;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.plugin.ConnectionHandler;
+import org.briarproject.bramble.api.plugin.PluginCallback;
+import org.briarproject.bramble.api.plugin.TransportConnectionReader;
+import org.briarproject.bramble.api.plugin.TransportConnectionWriter;
+import org.briarproject.bramble.api.plugin.TransportId;
+import org.briarproject.bramble.api.plugin.simplex.SimplexPlugin;
+import org.briarproject.bramble.api.properties.TransportProperties;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.util.Collection;
+import java.util.logging.Logger;
+
+import javax.annotation.concurrent.Immutable;
+
+import static java.util.Collections.singletonMap;
+import static java.util.logging.Level.WARNING;
+import static java.util.logging.Logger.getLogger;
+import static org.briarproject.bramble.api.plugin.Plugin.State.ACTIVE;
+import static org.briarproject.bramble.api.plugin.file.RemovableDriveConstants.ID;
+import static org.briarproject.bramble.api.plugin.file.RemovableDriveConstants.PROP_SUPPORTED;
+import static org.briarproject.bramble.util.LogUtils.logException;
+
+@Immutable
+@NotNullByDefault
+abstract class AbstractRemovableDrivePlugin implements SimplexPlugin {
+
+	private static final Logger LOG =
+			getLogger(AbstractRemovableDrivePlugin.class.getName());
+
+	private final long maxLatency;
+	private final PluginCallback callback;
+
+	abstract InputStream openInputStream(TransportProperties p)
+			throws IOException;
+
+	abstract OutputStream openOutputStream(TransportProperties p)
+			throws IOException;
+
+	AbstractRemovableDrivePlugin(PluginCallback callback, long maxLatency) {
+		this.callback = callback;
+		this.maxLatency = maxLatency;
+	}
+
+	@Override
+	public TransportId getId() {
+		return ID;
+	}
+
+	@Override
+	public long getMaxLatency() {
+		return maxLatency;
+	}
+
+	@Override
+	public int getMaxIdleTime() {
+		// Unused for simplex transports
+		throw new UnsupportedOperationException();
+	}
+
+	@Override
+	public void start() {
+		callback.mergeLocalProperties(
+				new TransportProperties(singletonMap(PROP_SUPPORTED, "true")));
+	}
+
+	@Override
+	public void stop() {
+	}
+
+	@Override
+	public State getState() {
+		return ACTIVE;
+	}
+
+	@Override
+	public int getReasonsDisabled() {
+		return 0;
+	}
+
+	@Override
+	public boolean shouldPoll() {
+		return false;
+	}
+
+	@Override
+	public int getPollingInterval() {
+		throw new UnsupportedOperationException();
+	}
+
+	@Override
+	public void poll(
+			Collection<Pair<TransportProperties, ConnectionHandler>> properties) {
+		throw new UnsupportedOperationException();
+	}
+
+	@Override
+	public boolean isLossyAndCheap() {
+		return true;
+	}
+
+	@Override
+	public TransportConnectionReader createReader(TransportProperties p) {
+		try {
+			return new TransportInputStreamReader(openInputStream(p));
+		} catch (IOException e) {
+			logException(LOG, WARNING, e);
+			return null;
+		}
+	}
+
+	@Override
+	public TransportConnectionWriter createWriter(TransportProperties p) {
+		try {
+			return new TransportOutputStreamWriter(this, openOutputStream(p));
+		} catch (IOException e) {
+			logException(LOG, WARNING, e);
+			return null;
+		}
+	}
+}

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

@@ -15,8 +15,8 @@ import java.util.logging.Logger;
 
 import static java.util.logging.Level.WARNING;
 import static java.util.logging.Logger.getLogger;
-import static org.briarproject.bramble.api.plugin.FileConstants.PROP_PATH;
 import static org.briarproject.bramble.api.plugin.Plugin.State.ACTIVE;
+import static org.briarproject.bramble.api.plugin.file.FileConstants.PROP_PATH;
 import static org.briarproject.bramble.util.LogUtils.logException;
 import static org.briarproject.bramble.util.StringUtils.isNullOrEmpty;
 
@@ -27,20 +27,20 @@ abstract class FilePlugin implements SimplexPlugin {
 			getLogger(FilePlugin.class.getName());
 
 	protected final PluginCallback callback;
-	protected final int maxLatency;
+	protected final long maxLatency;
 
 	protected abstract void writerFinished(File f, boolean exception);
 
 	protected abstract void readerFinished(File f, boolean exception,
 			boolean recognised);
 
-	FilePlugin(PluginCallback callback, int maxLatency) {
+	FilePlugin(PluginCallback callback, long maxLatency) {
 		this.callback = callback;
 		this.maxLatency = maxLatency;
 	}
 
 	@Override
-	public int getMaxLatency() {
+	public long getMaxLatency() {
 		return maxLatency;
 	}
 

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

@@ -27,7 +27,7 @@ class FileTransportWriter implements TransportConnectionWriter {
 	}
 
 	@Override
-	public int getMaxLatency() {
+	public long getMaxLatency() {
 		return plugin.getMaxLatency();
 	}
 
@@ -36,6 +36,11 @@ class FileTransportWriter implements TransportConnectionWriter {
 		return plugin.getMaxIdleTime();
 	}
 
+	@Override
+	public boolean isLossyAndCheap() {
+		return plugin.isLossyAndCheap();
+	}
+
 	@Override
 	public OutputStream getOutputStream() {
 		return out;

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

@@ -0,0 +1,125 @@
+package org.briarproject.bramble.plugin.file;
+
+import org.briarproject.bramble.api.contact.ContactId;
+import org.briarproject.bramble.api.db.DatabaseComponent;
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.lifecycle.IoExecutor;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.plugin.file.RemovableDriveManager;
+import org.briarproject.bramble.api.plugin.file.RemovableDriveTask;
+import org.briarproject.bramble.api.properties.TransportProperties;
+import org.briarproject.bramble.api.properties.TransportPropertyManager;
+import org.briarproject.bramble.api.transport.KeyManager;
+
+import java.util.concurrent.Executor;
+
+import javax.annotation.Nullable;
+import javax.annotation.concurrent.GuardedBy;
+import javax.annotation.concurrent.ThreadSafe;
+import javax.inject.Inject;
+
+import static org.briarproject.bramble.api.plugin.file.RemovableDriveConstants.ID;
+import static org.briarproject.bramble.api.plugin.file.RemovableDriveConstants.PROP_SUPPORTED;
+import static org.briarproject.bramble.plugin.file.RemovableDrivePluginFactory.MAX_LATENCY;
+
+@ThreadSafe
+@NotNullByDefault
+class RemovableDriveManagerImpl
+		implements RemovableDriveManager, RemovableDriveTaskRegistry {
+
+	private final Executor ioExecutor;
+	private final DatabaseComponent db;
+	private final KeyManager keyManager;
+	private final TransportPropertyManager transportPropertyManager;
+	private final RemovableDriveTaskFactory taskFactory;
+	private final Object lock = new Object();
+
+	@GuardedBy("lock")
+	@Nullable
+	private RemovableDriveTask reader = null;
+	@GuardedBy("lock")
+	@Nullable
+	private RemovableDriveTask writer = null;
+
+	@Inject
+	RemovableDriveManagerImpl(
+			@IoExecutor Executor ioExecutor,
+			DatabaseComponent db,
+			KeyManager keyManager,
+			TransportPropertyManager transportPropertyManager,
+			RemovableDriveTaskFactory taskFactory) {
+		this.ioExecutor = ioExecutor;
+		this.db = db;
+		this.keyManager = keyManager;
+		this.transportPropertyManager = transportPropertyManager;
+		this.taskFactory = taskFactory;
+	}
+
+	@Nullable
+	@Override
+	public RemovableDriveTask getCurrentReaderTask() {
+		synchronized (lock) {
+			return reader;
+		}
+	}
+
+	@Nullable
+	@Override
+	public RemovableDriveTask getCurrentWriterTask() {
+		synchronized (lock) {
+			return writer;
+		}
+	}
+
+	@Override
+	public RemovableDriveTask startReaderTask(TransportProperties p) {
+		RemovableDriveTask created;
+		synchronized (lock) {
+			if (reader != null) return reader;
+			reader = created = taskFactory.createReader(this, p);
+		}
+		ioExecutor.execute(created);
+		return created;
+	}
+
+	@Override
+	public RemovableDriveTask startWriterTask(ContactId c,
+			TransportProperties p) {
+		RemovableDriveTask created;
+		synchronized (lock) {
+			if (writer != null) return writer;
+			writer = created = taskFactory.createWriter(this, c, p);
+		}
+		ioExecutor.execute(created);
+		return created;
+	}
+
+	@Override
+	public boolean isTransportSupportedByContact(ContactId c)
+			throws DbException {
+		if (!keyManager.canSendOutgoingStreams(c, ID)) return false;
+		TransportProperties p =
+				transportPropertyManager.getRemoteProperties(c, ID);
+		return "true".equals(p.get(PROP_SUPPORTED));
+	}
+
+	@Override
+	public boolean isWriterTaskNeeded(ContactId c) throws DbException {
+		return db.transactionWithResult(true, txn ->
+				db.containsAnythingToSend(txn, c, MAX_LATENCY, true));
+	}
+
+	@Override
+	public void removeReader(RemovableDriveTask task) {
+		synchronized (lock) {
+			if (reader == task) reader = null;
+		}
+	}
+
+	@Override
+	public void removeWriter(RemovableDriveTask task) {
+		synchronized (lock) {
+			if (writer == task) writer = null;
+		}
+	}
+}

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

@@ -0,0 +1,25 @@
+package org.briarproject.bramble.plugin.file;
+
+import org.briarproject.bramble.api.plugin.file.RemovableDriveManager;
+
+import javax.inject.Singleton;
+
+import dagger.Module;
+import dagger.Provides;
+
+@Module
+public class RemovableDriveModule {
+
+	@Provides
+	@Singleton
+	RemovableDriveManager provideRemovableDriveManager(
+			RemovableDriveManagerImpl removableDriveManager) {
+		return removableDriveManager;
+	}
+
+	@Provides
+	RemovableDriveTaskFactory provideTaskFactory(
+			RemovableDriveTaskFactoryImpl taskFactory) {
+		return taskFactory;
+	}
+}

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

@@ -0,0 +1,39 @@
+package org.briarproject.bramble.plugin.file;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.plugin.PluginCallback;
+import org.briarproject.bramble.api.properties.TransportProperties;
+
+import java.io.FileInputStream;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+
+import javax.annotation.concurrent.Immutable;
+
+import static org.briarproject.bramble.api.plugin.file.RemovableDriveConstants.PROP_PATH;
+import static org.briarproject.bramble.util.StringUtils.isNullOrEmpty;
+
+@Immutable
+@NotNullByDefault
+class RemovableDrivePlugin extends AbstractRemovableDrivePlugin {
+
+	RemovableDrivePlugin(PluginCallback callback, long maxLatency) {
+		super(callback, maxLatency);
+	}
+
+	@Override
+	InputStream openInputStream(TransportProperties p) throws IOException {
+		String path = p.get(PROP_PATH);
+		if (isNullOrEmpty(path)) throw new IllegalArgumentException();
+		return new FileInputStream(path);
+	}
+
+	@Override
+	OutputStream openOutputStream(TransportProperties p) throws IOException {
+		String path = p.get(PROP_PATH);
+		if (isNullOrEmpty(path)) throw new IllegalArgumentException();
+		return new FileOutputStream(path);
+	}
+}

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

@@ -0,0 +1,41 @@
+package org.briarproject.bramble.plugin.file;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.plugin.PluginCallback;
+import org.briarproject.bramble.api.plugin.TransportId;
+import org.briarproject.bramble.api.plugin.simplex.SimplexPlugin;
+import org.briarproject.bramble.api.plugin.simplex.SimplexPluginFactory;
+
+import javax.annotation.Nullable;
+import javax.annotation.concurrent.Immutable;
+import javax.inject.Inject;
+
+import static java.util.concurrent.TimeUnit.DAYS;
+import static org.briarproject.bramble.api.plugin.file.RemovableDriveConstants.ID;
+
+@Immutable
+@NotNullByDefault
+public class RemovableDrivePluginFactory implements SimplexPluginFactory {
+
+	static final long MAX_LATENCY = DAYS.toMillis(28);
+
+	@Inject
+	RemovableDrivePluginFactory() {
+	}
+
+	@Override
+	public TransportId getId() {
+		return ID;
+	}
+
+	@Override
+	public long getMaxLatency() {
+		return MAX_LATENCY;
+	}
+
+	@Nullable
+	@Override
+	public SimplexPlugin createPlugin(PluginCallback callback) {
+		return new RemovableDrivePlugin(callback, MAX_LATENCY);
+	}
+}

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

@@ -0,0 +1,69 @@
+package org.briarproject.bramble.plugin.file;
+
+import org.briarproject.bramble.api.connection.ConnectionManager;
+import org.briarproject.bramble.api.event.EventBus;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.plugin.PluginManager;
+import org.briarproject.bramble.api.plugin.TransportConnectionReader;
+import org.briarproject.bramble.api.properties.TransportProperties;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.concurrent.Executor;
+import java.util.logging.Logger;
+
+import static java.util.logging.Logger.getLogger;
+import static org.briarproject.bramble.api.plugin.file.RemovableDriveConstants.ID;
+
+@NotNullByDefault
+class RemovableDriveReaderTask extends RemovableDriveTaskImpl {
+
+	private final static Logger LOG =
+			getLogger(RemovableDriveReaderTask.class.getName());
+
+	RemovableDriveReaderTask(
+			Executor eventExecutor,
+			PluginManager pluginManager,
+			ConnectionManager connectionManager,
+			EventBus eventBus,
+			RemovableDriveTaskRegistry registry,
+			TransportProperties transportProperties) {
+		super(eventExecutor, pluginManager, connectionManager, eventBus,
+				registry, transportProperties);
+	}
+
+	@Override
+	public void run() {
+		TransportConnectionReader r =
+				getPlugin().createReader(transportProperties);
+		if (r == null) {
+			LOG.warning("Failed to create reader");
+			registry.removeReader(this);
+			setSuccess(false);
+			return;
+		}
+		connectionManager.manageIncomingConnection(ID, new DecoratedReader(r));
+	}
+
+	private class DecoratedReader implements TransportConnectionReader {
+
+		private final TransportConnectionReader delegate;
+
+		private DecoratedReader(TransportConnectionReader delegate) {
+			this.delegate = delegate;
+		}
+
+		@Override
+		public InputStream getInputStream() throws IOException {
+			return delegate.getInputStream();
+		}
+
+		@Override
+		public void dispose(boolean exception, boolean recognised)
+				throws IOException {
+			delegate.dispose(exception, recognised);
+			registry.removeReader(RemovableDriveReaderTask.this);
+			setSuccess(!exception && recognised);
+		}
+	}
+}

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

@@ -0,0 +1,16 @@
+package org.briarproject.bramble.plugin.file;
+
+import org.briarproject.bramble.api.contact.ContactId;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.plugin.file.RemovableDriveTask;
+import org.briarproject.bramble.api.properties.TransportProperties;
+
+@NotNullByDefault
+interface RemovableDriveTaskFactory {
+
+	RemovableDriveTask createReader(RemovableDriveTaskRegistry registry,
+			TransportProperties p);
+
+	RemovableDriveTask createWriter(RemovableDriveTaskRegistry registry,
+			ContactId c, TransportProperties p);
+}

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

@@ -0,0 +1,55 @@
+package org.briarproject.bramble.plugin.file;
+
+import org.briarproject.bramble.api.connection.ConnectionManager;
+import org.briarproject.bramble.api.contact.ContactId;
+import org.briarproject.bramble.api.db.DatabaseComponent;
+import org.briarproject.bramble.api.event.EventBus;
+import org.briarproject.bramble.api.event.EventExecutor;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.plugin.PluginManager;
+import org.briarproject.bramble.api.plugin.file.RemovableDriveTask;
+import org.briarproject.bramble.api.properties.TransportProperties;
+
+import java.util.concurrent.Executor;
+
+import javax.annotation.concurrent.Immutable;
+import javax.inject.Inject;
+
+@Immutable
+@NotNullByDefault
+class RemovableDriveTaskFactoryImpl implements RemovableDriveTaskFactory {
+
+	private final DatabaseComponent db;
+	private final Executor eventExecutor;
+	private final PluginManager pluginManager;
+	private final ConnectionManager connectionManager;
+	private final EventBus eventBus;
+
+	@Inject
+	RemovableDriveTaskFactoryImpl(
+			DatabaseComponent db,
+			@EventExecutor Executor eventExecutor,
+			PluginManager pluginManager,
+			ConnectionManager connectionManager,
+			EventBus eventBus) {
+		this.db = db;
+		this.eventExecutor = eventExecutor;
+		this.pluginManager = pluginManager;
+		this.connectionManager = connectionManager;
+		this.eventBus = eventBus;
+	}
+
+	@Override
+	public RemovableDriveTask createReader(RemovableDriveTaskRegistry registry,
+			TransportProperties p) {
+		return new RemovableDriveReaderTask(eventExecutor, pluginManager,
+				connectionManager, eventBus, registry, p);
+	}
+
+	@Override
+	public RemovableDriveTask createWriter(RemovableDriveTaskRegistry registry,
+			ContactId c, TransportProperties p) {
+		return new RemovableDriveWriterTask(db, eventExecutor, pluginManager,
+				connectionManager, eventBus, registry, c, p);
+	}
+}