Update test class.

Fix IllegalStateException when creating image attachments

Closes #1647

See merge request briar/briar!1187

.idea/codeStyles/Project.xml

@@ -28,6 +28,20 @@
       <option name="JD_ALIGN_EXCEPTION_COMMENTS" value="false" />
     </JavaCodeStyleSettings>
     <JetCodeStyleSettings>
+      <option name="PACKAGES_TO_USE_STAR_IMPORTS">
+        <value />
+      </option>
+      <option name="PACKAGES_IMPORT_LAYOUT">
+        <value>
+          <package name="" alias="false" withSubpackages="true" />
+          <package name="java" alias="false" withSubpackages="true" />
+          <package name="javax" alias="false" withSubpackages="true" />
+          <package name="kotlin" alias="false" withSubpackages="true" />
+          <package name="" alias="true" withSubpackages="true" />
+        </value>
+      </option>
+      <option name="NAME_COUNT_TO_USE_STAR_IMPORT" value="2147483647" />
+      <option name="NAME_COUNT_TO_USE_STAR_IMPORT_FOR_MEMBERS" value="2147483647" />
       <option name="CODE_STYLE_DEFAULTS" value="KOTLIN_OFFICIAL" />
     </JetCodeStyleSettings>
     <XML>

bramble-android/.gitignore

@@ -3,3 +3,4 @@ gen
 build
 .settings
 src/main/res/raw/*.zip
+src/main/jniLibs

bramble-android/build.gradle

@@ -5,14 +5,14 @@ apply plugin: 'witness'
 apply from: 'witness.gradle'
 
 android {
-	compileSdkVersion 29
-	buildToolsVersion '29.0.2'
+	compileSdkVersion rootProject.ext.compileSdkVersion
+	buildToolsVersion rootProject.ext.buildToolsVersion
 
 	defaultConfig {
-		minSdkVersion 16
-		targetSdkVersion 28
-		versionCode 10209
-		versionName "1.2.9"
+		minSdkVersion rootProject.ext.minSdkVersion
+		targetSdkVersion rootProject.ext.targetSdkVersion
+		versionCode rootProject.ext.versionCode
+		versionName rootProject.ext.versionName
 		consumerProguardFiles 'proguard-rules.txt'
 
 		testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
@@ -53,10 +53,12 @@ dependencies {
 }
 
 def torBinariesDir = 'src/main/res/raw'
+def torLibsDir = 'src/main/jniLibs'
 
 task cleanTorBinaries {
 	doLast {
 		delete fileTree(torBinariesDir) { include '*.zip' }
+		delete fileTree(torLibsDir) { include '**/*.so' }
 	}
 }
 
@@ -67,8 +69,36 @@ task unpackTorBinaries {
 		copy {
 			from configurations.tor.collect { zipTree(it) }
 			into torBinariesDir
-			// TODO: Remove after next Tor upgrade, which won't include non-PIE binaries
-			include 'geoip.zip', '*_pie.zip'
+			include 'geoip.zip'
+		}
+		configurations.tor.each { outer ->
+			zipTree(outer).each { inner ->
+				if (inner.name.endsWith('_arm_pie.zip')) {
+					copy {
+						from zipTree(inner)
+						into torLibsDir
+						rename '(.*)', 'armeabi-v7a/lib$1.so'
+					}
+				} else if (inner.name.endsWith('_arm64_pie.zip')) {
+					copy {
+						from zipTree(inner)
+						into torLibsDir
+						rename '(.*)', 'arm64-v8a/lib$1.so'
+					}
+				} else if (inner.name.endsWith('_x86_pie.zip')) {
+					copy {
+						from zipTree(inner)
+						into torLibsDir
+						rename '(.*)', 'x86/lib$1.so'
+					}
+				} else if (inner.name.endsWith('_x86_64_pie.zip')) {
+					copy {
+						from zipTree(inner)
+						into torLibsDir
+						rename '(.*)', 'x86_64/lib$1.so'
+					}
+				}
+			}
 		}
 	}
 	dependsOn cleanTorBinaries
@@ -76,5 +106,6 @@ task unpackTorBinaries {
 
 tasks.withType(MergeResources) {
 	inputs.dir torBinariesDir
+	inputs.dir torLibsDir
 	dependsOn unpackTorBinaries
 }

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

@@ -135,6 +135,7 @@ class AndroidBluetoothPlugin
 	@Override
 	@Nullable
 	String getBluetoothAddress() {
+		if (adapter == null) return null;
 		String address = AndroidUtils.getBluetoothAddress(app, adapter);
 		return address.isEmpty() ? null : address;
 	}

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

@@ -24,6 +24,7 @@ import java.util.concurrent.Executor;
 import javax.annotation.concurrent.Immutable;
 import javax.inject.Inject;
 
+import static android.os.Build.BRAND;
 import static org.briarproject.bramble.api.plugin.BluetoothConstants.ID;
 
 @Immutable
@@ -81,8 +82,12 @@ public class AndroidBluetoothPluginFactory implements DuplexPluginFactory {
 
 	@Override
 	public DuplexPlugin createPlugin(PluginCallback callback) {
+		// On Motorola devices, don't try to open multiple connections - the
+		// Bluetooth stack can't handle it
+		// TODO: Narrow this down to specific models/versions if possible
+		boolean singleConnection = "motorola".equalsIgnoreCase(BRAND);
 		BluetoothConnectionLimiter connectionLimiter =
-				new BluetoothConnectionLimiterImpl(eventBus);
+				new BluetoothConnectionLimiterImpl(eventBus, singleConnection);
 		BluetoothConnectionFactory<BluetoothSocket> connectionFactory =
 				new AndroidBluetoothConnectionFactory(connectionLimiter,
 						wakeLockManager, timeoutMonitor);

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

@@ -16,19 +16,42 @@ import org.briarproject.bramble.api.system.AndroidWakeLockManager;
 import org.briarproject.bramble.api.system.Clock;
 import org.briarproject.bramble.api.system.LocationUtils;
 import org.briarproject.bramble.api.system.ResourceProvider;
+import org.briarproject.bramble.util.AndroidUtils;
 
 import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileNotFoundException;
 import java.io.IOException;
+import java.util.ArrayList;
+import java.util.List;
 import java.util.concurrent.Executor;
+import java.util.logging.Logger;
+import java.util.zip.ZipEntry;
+import java.util.zip.ZipInputStream;
 
 import javax.net.SocketFactory;
 
+import static android.os.Build.VERSION.SDK_INT;
+import static java.util.Arrays.asList;
+import static java.util.logging.Level.INFO;
+import static java.util.logging.Logger.getLogger;
+
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
 class AndroidTorPlugin extends TorPlugin {
 
+	private static final List<String> LIBRARY_ARCHITECTURES =
+			asList("armeabi-v7a", "arm64-v8a", "x86", "x86_64");
+
+	private static final String TOR_LIB_NAME = "libtor.so";
+	private static final String OBFS4_LIB_NAME = "libobfs4proxy.so";
+
+	private static final Logger LOG =
+			getLogger(AndroidTorPlugin.class.getName());
+
 	private final Application app;
 	private final AndroidWakeLock wakeLock;
+	private final File torLib, obfs4Lib;
 
 	AndroidTorPlugin(Executor ioExecutor,
 			Executor wakefulIoExecutor,
@@ -55,6 +78,9 @@ class AndroidTorPlugin extends TorPlugin {
 				maxIdleTime, torDirectory);
 		this.app = app;
 		wakeLock = wakeLockManager.createWakeLock("TorPlugin");
+		String nativeLibDir = app.getApplicationInfo().nativeLibraryDir;
+		torLib = new File(nativeLibDir, TOR_LIB_NAME);
+		obfs4Lib = new File(nativeLibDir, OBFS4_LIB_NAME);
 	}
 
 	@Override
@@ -85,4 +111,112 @@ class AndroidTorPlugin extends TorPlugin {
 		super.stop();
 		wakeLock.release();
 	}
+
+	@Override
+	protected File getTorExecutableFile() {
+		return torLib.exists() ? torLib : super.getTorExecutableFile();
+	}
+
+	@Override
+	protected File getObfs4ExecutableFile() {
+		return obfs4Lib.exists() ? obfs4Lib : super.getObfs4ExecutableFile();
+	}
+
+	@Override
+	protected void installTorExecutable() throws IOException {
+		File extracted = super.getTorExecutableFile();
+		if (torLib.exists()) {
+			// If an older version left behind a Tor binary, delete it
+			if (extracted.exists()) {
+				if (extracted.delete()) LOG.info("Deleted Tor binary");
+				else LOG.info("Failed to delete Tor binary");
+			}
+		} else if (SDK_INT < 29) {
+			// The binary wasn't extracted at install time. Try to extract it
+			extractLibraryFromApk(TOR_LIB_NAME, extracted);
+		} else {
+			// No point extracting the binary, we won't be allowed to execute it
+			throw new FileNotFoundException(torLib.getAbsolutePath());
+		}
+	}
+
+	@Override
+	protected void installObfs4Executable() throws IOException {
+		File extracted = super.getObfs4ExecutableFile();
+		if (obfs4Lib.exists()) {
+			// If an older version left behind an obfs4 binary, delete it
+			if (extracted.exists()) {
+				if (extracted.delete()) LOG.info("Deleted obfs4 binary");
+				else LOG.info("Failed to delete obfs4 binary");
+			}
+		} else if (SDK_INT < 29) {
+			// The binary wasn't extracted at install time. Try to extract it
+			extractLibraryFromApk(OBFS4_LIB_NAME, extracted);
+		} else {
+			// No point extracting the binary, we won't be allowed to execute it
+			throw new FileNotFoundException(obfs4Lib.getAbsolutePath());
+		}
+	}
+
+	private void extractLibraryFromApk(String libName, File dest)
+			throws IOException {
+		File sourceDir = new File(app.getApplicationInfo().sourceDir);
+		if (sourceDir.isFile()) {
+			// Look for other APK files in the same directory, if we're allowed
+			File parent = sourceDir.getParentFile();
+			if (parent != null) sourceDir = parent;
+		}
+		List<String> libPaths = getSupportedLibraryPaths(libName);
+		for (File apk : findApkFiles(sourceDir)) {
+			ZipInputStream zin = new ZipInputStream(new FileInputStream(apk));
+			for (ZipEntry e = zin.getNextEntry(); e != null;
+					e = zin.getNextEntry()) {
+				if (libPaths.contains(e.getName())) {
+					if (LOG.isLoggable(INFO)) {
+						LOG.info("Extracting " + e.getName()
+								+ " from " + apk.getAbsolutePath());
+					}
+					extract(zin, dest); // Zip input stream will be closed
+					return;
+				}
+			}
+			zin.close();
+		}
+		throw new FileNotFoundException(libName);
+	}
+
+	/**
+	 * Returns all files with the extension .apk or .APK under the given root.
+	 */
+	private List<File> findApkFiles(File root) {
+		List<File> files = new ArrayList<>();
+		findApkFiles(root, files);
+		return files;
+	}
+
+	private void findApkFiles(File f, List<File> files) {
+		if (f.isFile() && f.getName().toLowerCase().endsWith(".apk")) {
+			files.add(f);
+		} else if (f.isDirectory()) {
+			File[] children = f.listFiles();
+			if (children != null) {
+				for (File child : children) findApkFiles(child, files);
+			}
+		}
+	}
+
+	/**
+	 * Returns the paths at which libraries with the given name would be found
+	 * inside an APK file, for all architectures supported by the device, in
+	 * order of preference.
+	 */
+	private List<String> getSupportedLibraryPaths(String libName) {
+		List<String> architectures = new ArrayList<>();
+		for (String abi : AndroidUtils.getSupportedArchitectures()) {
+			if (LIBRARY_ARCHITECTURES.contains(abi)) {
+				architectures.add("lib/" + abi + "/" + libName);
+			}
+		}
+		return architectures;
+	}
 }

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

@@ -22,6 +22,8 @@ public abstract class AbstractDuplexTransportConnection
 	private final Writer writer;
 	private final AtomicBoolean halfClosed, closed;
 
+	private volatile boolean markedForClose = false;
+
 	protected AbstractDuplexTransportConnection(Plugin plugin) {
 		this.plugin = plugin;
 		reader = new Reader();
@@ -52,6 +54,16 @@ public abstract class AbstractDuplexTransportConnection
 		return remote;
 	}
 
+	@Override
+	public boolean isMarkedForClose() {
+		return markedForClose;
+	}
+
+	@Override
+	public void markForClose() {
+		markedForClose = true;
+	}
+
 	private class Reader implements TransportConnectionReader {
 
 		@Override

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

@@ -1,6 +1,7 @@
 package org.briarproject.bramble.api.plugin.duplex;
 
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.plugin.ConnectionHandler;
 import org.briarproject.bramble.api.plugin.TransportConnectionReader;
 import org.briarproject.bramble.api.plugin.TransportConnectionWriter;
 import org.briarproject.bramble.api.properties.TransportProperties;
@@ -30,4 +31,17 @@ public interface DuplexTransportConnection {
 	 * the remote peer.
 	 */
 	TransportProperties getRemoteProperties();
+
+	/**
+	 * Returns true if the connection should be closed immediately without
+	 * sending anything.
+	 */
+	boolean isMarkedForClose();
+
+	/**
+	 * Call this method before the connection is passed to its
+	 * {@link ConnectionHandler} if the connection should be closed immediately
+	 * without sending anything.
+	 */
+	void markForClose();
 }

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

@@ -33,6 +33,7 @@ abstract class DuplexSyncConnection extends SyncConnection
 
 	final Executor ioExecutor;
 	final TransportId transportId;
+	final DuplexTransportConnection connection;
 	final TransportConnectionReader reader;
 	final TransportConnectionWriter writer;
 	final TransportProperties remote;
@@ -80,6 +81,7 @@ abstract class DuplexSyncConnection extends SyncConnection
 				transportPropertyManager);
 		this.ioExecutor = ioExecutor;
 		this.transportId = transportId;
+		this.connection = connection;
 		reader = connection.getReader();
 		writer = connection.getWriter();
 		remote = connection.getRemoteProperties();
@@ -96,6 +98,13 @@ abstract class DuplexSyncConnection extends SyncConnection
 		disposeOnError(writer);
 	}
 
+	void closeOutgoingStream(StreamContext ctx, TransportConnectionWriter w)
+			throws IOException {
+		StreamWriter streamWriter = streamWriterFactory.createStreamWriter(
+				w.getOutputStream(), ctx);
+		streamWriter.sendEndOfStream();
+	}
+
 	SyncSession createDuplexOutgoingSession(StreamContext ctx,
 			TransportConnectionWriter w, @Nullable Priority priority)
 			throws IOException {

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

@@ -93,10 +93,16 @@ class IncomingDuplexSyncConnection extends DuplexSyncConnection
 			return;
 		}
 		try {
-			// Create and run the outgoing session
-			SyncSession out = createDuplexOutgoingSession(ctx, writer, null);
-			setOutgoingSession(out);
-			out.run();
+			if (connection.isMarkedForClose()) {
+				// Close the outgoing stream without sending anything
+				closeOutgoingStream(ctx, writer);
+			} else {
+				// Create and run the outgoing session
+				SyncSession out =
+						createDuplexOutgoingSession(ctx, writer, null);
+				setOutgoingSession(out);
+				out.run();
+			}
 			writer.dispose(false);
 		} catch (IOException e) {
 			logException(LOG, WARNING, e);

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

@@ -65,11 +65,16 @@ class OutgoingDuplexSyncConnection extends DuplexSyncConnection
 		Priority priority = generatePriority();
 		ioExecutor.execute(() -> runIncomingSession(priority));
 		try {
-			// Create and run the outgoing session
-			SyncSession out =
-					createDuplexOutgoingSession(ctx, writer, priority);
-			setOutgoingSession(out);
-			out.run();
+			if (connection.isMarkedForClose()) {
+				// Close the outgoing stream without sending anything
+				closeOutgoingStream(ctx, writer);
+			} else {
+				// Create and run the outgoing session
+				SyncSession out =
+						createDuplexOutgoingSession(ctx, writer, priority);
+				setOutgoingSession(out);
+				out.run();
+			}
 			writer.dispose(false);
 		} catch (IOException e) {
 			logException(LOG, WARNING, e);

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

@@ -1,5 +1,6 @@
 package org.briarproject.bramble.keyagreement;
 
+import org.briarproject.bramble.api.Pair;
 import org.briarproject.bramble.api.crypto.KeyAgreementCrypto;
 import org.briarproject.bramble.api.crypto.KeyPair;
 import org.briarproject.bramble.api.data.BdfList;
@@ -8,6 +9,8 @@ import org.briarproject.bramble.api.keyagreement.KeyAgreementListener;
 import org.briarproject.bramble.api.keyagreement.Payload;
 import org.briarproject.bramble.api.keyagreement.TransportDescriptor;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.plugin.BluetoothConstants;
+import org.briarproject.bramble.api.plugin.LanTcpConstants;
 import org.briarproject.bramble.api.plugin.Plugin;
 import org.briarproject.bramble.api.plugin.PluginManager;
 import org.briarproject.bramble.api.plugin.TransportId;
@@ -19,7 +22,9 @@ import org.briarproject.bramble.api.record.RecordWriterFactory;
 import java.io.IOException;
 import java.io.InputStream;
 import java.util.ArrayList;
+import java.util.HashMap;
 import java.util.List;
+import java.util.Map;
 import java.util.concurrent.Callable;
 import java.util.concurrent.CopyOnWriteArrayList;
 import java.util.concurrent.CountDownLatch;
@@ -28,8 +33,10 @@ import java.util.logging.Logger;
 
 import javax.annotation.Nullable;
 
+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.keyagreement.KeyAgreementConstants.CONNECTION_TIMEOUT;
 import static org.briarproject.bramble.util.LogUtils.logException;
 
@@ -41,7 +48,10 @@ class KeyAgreementConnector {
 	}
 
 	private static final Logger LOG =
-			Logger.getLogger(KeyAgreementConnector.class.getName());
+			getLogger(KeyAgreementConnector.class.getName());
+
+	private static final List<TransportId> PREFERRED_TRANSPORTS =
+			asList(BluetoothConstants.ID, LanTcpConstants.ID);
 
 	private final Callbacks callbacks;
 	private final KeyAgreementCrypto keyAgreementCrypto;
@@ -105,24 +115,35 @@ class KeyAgreementConnector {
 		this.alice = alice;
 		aliceLatch.countDown();
 
-		// Start connecting over supported transports
+		// Start connecting over supported transports in order of preference
 		if (LOG.isLoggable(INFO)) {
 			LOG.info("Starting outgoing BQP connections as "
 					+ (alice ? "Alice" : "Bob"));
 		}
+		Map<TransportId, TransportDescriptor> descriptors = new HashMap<>();
 		for (TransportDescriptor d : remotePayload.getTransportDescriptors()) {
-			Plugin p = pluginManager.getPlugin(d.getId());
-			if (p instanceof DuplexPlugin) {
+			descriptors.put(d.getId(), d);
+		}
+		List<Pair<DuplexPlugin, BdfList>> transports = new ArrayList<>();
+		for (TransportId id : PREFERRED_TRANSPORTS) {
+			TransportDescriptor d = descriptors.get(id);
+			Plugin p = pluginManager.getPlugin(id);
+			if (d != null && p instanceof DuplexPlugin) {
 				if (LOG.isLoggable(INFO))
-					LOG.info("Connecting via " + d.getId());
-				DuplexPlugin plugin = (DuplexPlugin) p;
-				byte[] commitment = remotePayload.getCommitment();
-				BdfList descriptor = d.getDescriptor();
-				connectionChooser.submit(new ReadableTask(
-						new ConnectorTask(plugin, commitment, descriptor)));
+					LOG.info("Connecting via " + id);
+				transports.add(new Pair<>((DuplexPlugin) p, d.getDescriptor()));
 			}
 		}
 
+		// TODO: If we don't have any transports in common with the peer,
+		//  warn the user and give up (#1224)
+
+		if (!transports.isEmpty()) {
+			byte[] commitment = remotePayload.getCommitment();
+			connectionChooser.submit(new ReadableTask(new ConnectorTask(
+					transports, commitment)));
+		}
+
 		// Get chosen connection
 		try {
 			KeyAgreementConnection chosen =
@@ -148,15 +169,13 @@ class KeyAgreementConnector {
 
 	private class ConnectorTask implements Callable<KeyAgreementConnection> {
 
+		private final List<Pair<DuplexPlugin, BdfList>> transports;
 		private final byte[] commitment;
-		private final BdfList descriptor;
-		private final DuplexPlugin plugin;
 
-		private ConnectorTask(DuplexPlugin plugin, byte[] commitment,
-				BdfList descriptor) {
-			this.plugin = plugin;
+		private ConnectorTask(List<Pair<DuplexPlugin, BdfList>> transports,
+				byte[] commitment) {
+			this.transports = transports;
 			this.commitment = commitment;
-			this.descriptor = descriptor;
 		}
 
 		@Nullable
@@ -164,13 +183,18 @@ class KeyAgreementConnector {
 		public KeyAgreementConnection call() throws Exception {
 			// Repeat attempts until we connect, get stopped, or get interrupted
 			while (!stopped) {
-				DuplexTransportConnection conn =
-						plugin.createKeyAgreementConnection(commitment,
-								descriptor);
-				if (conn != null) {
-					if (LOG.isLoggable(INFO))
-						LOG.info(plugin.getId() + ": Outgoing connection");
-					return new KeyAgreementConnection(conn, plugin.getId());
+				for (Pair<DuplexPlugin, BdfList> pair : transports) {
+					if (stopped) return null;
+					DuplexPlugin plugin = pair.getFirst();
+					BdfList descriptor = pair.getSecond();
+					DuplexTransportConnection conn =
+							plugin.createKeyAgreementConnection(commitment,
+									descriptor);
+					if (conn != null) {
+						if (LOG.isLoggable(INFO))
+							LOG.info(plugin.getId() + ": Outgoing connection");
+						return new KeyAgreementConnection(conn, plugin.getId());
+					}
 				}
 				// Wait 2s before retry (to circumvent transient failures)
 				Thread.sleep(2000);

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

@@ -23,7 +23,9 @@ interface BluetoothConnectionLimiter {
 	boolean canOpenContactConnection();
 
 	/**
-	 * Informs the limiter that the given connection has been opened.
+	 * Informs the limiter that the given connection has been opened. If the
+	 * connection is above the limit it will be
+	 * {@link DuplexTransportConnection#markForClose() marked for close}.
 	 */
 	void connectionOpened(DuplexTransportConnection conn);
 

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

@@ -24,6 +24,7 @@ class BluetoothConnectionLimiterImpl implements BluetoothConnectionLimiter {
 			getLogger(BluetoothConnectionLimiterImpl.class.getName());
 
 	private final EventBus eventBus;
+	private final boolean singleConnection;
 
 	private final Object lock = new Object();
 	@GuardedBy("lock")
@@ -32,8 +33,10 @@ class BluetoothConnectionLimiterImpl implements BluetoothConnectionLimiter {
 	@GuardedBy("lock")
 	private boolean keyAgreementInProgress = false;
 
-	BluetoothConnectionLimiterImpl(EventBus eventBus) {
+	BluetoothConnectionLimiterImpl(EventBus eventBus,
+			boolean singleConnection) {
 		this.eventBus = eventBus;
+		this.singleConnection = singleConnection;
 	}
 
 	@Override
@@ -59,6 +62,9 @@ class BluetoothConnectionLimiterImpl implements BluetoothConnectionLimiter {
 			if (keyAgreementInProgress) {
 				LOG.info("Can't open contact connection during key agreement");
 				return false;
+			} else if (singleConnection && !connections.isEmpty()) {
+				LOG.info("Can't open contact connection due to limit");
+				return false;
 			} else {
 				LOG.info("Can open contact connection");
 				return true;
@@ -68,12 +74,18 @@ class BluetoothConnectionLimiterImpl implements BluetoothConnectionLimiter {
 
 	@Override
 	public void connectionOpened(DuplexTransportConnection conn) {
+		boolean shouldClose = false;
 		synchronized (lock) {
 			connections.add(conn);
 			if (LOG.isLoggable(INFO)) {
 				LOG.info("Connection opened, " + connections.size() + " open");
 			}
+			if (singleConnection && connections.size() > 1) {
+				LOG.info("Marking connection for close");
+				shouldClose = true;
+			}
 		}
+		if (shouldClose) conn.markForClose();
 	}
 
 	@Override

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

@@ -436,8 +436,10 @@ abstract class BluetoothPlugin<S, SS> implements DuplexPlugin, EventListener {
 		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);
+			if (LOG.isLoggable(INFO)) {
+				LOG.info("Discovering address for key agreement UUID " +
+						uuid);
+			}
 			conn = discoverAndConnect(uuid);
 		} else {
 			String address;

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

@@ -132,7 +132,7 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 	private final CircumventionProvider circumventionProvider;
 	private final ResourceProvider resourceProvider;
 	private final int maxLatency, maxIdleTime, socketTimeout;
-	private final File torDirectory, torFile, geoIpFile, obfs4File, configFile;
+	private final File torDirectory, geoIpFile, configFile;
 	private final File doneFile, cookieFile;
 	private final AtomicBoolean used = new AtomicBoolean(false);
 
@@ -181,9 +181,7 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 			socketTimeout = Integer.MAX_VALUE;
 		else socketTimeout = maxIdleTime * 2;
 		this.torDirectory = torDirectory;
-		torFile = new File(torDirectory, "tor");
 		geoIpFile = new File(torDirectory, "geoip");
-		obfs4File = new File(torDirectory, "obfs4proxy");
 		configFile = new File(torDirectory, "torrc");
 		doneFile = new File(torDirectory, "done");
 		cookieFile = new File(torDirectory, ".tor/control_auth_cookie");
@@ -192,6 +190,14 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 				new PoliteExecutor("TorPlugin", ioExecutor, 1);
 	}
 
+	protected File getTorExecutableFile() {
+		return new File(torDirectory, "tor");
+	}
+
+	protected File getObfs4ExecutableFile() {
+		return new File(torDirectory, "obfs4proxy");
+	}
+
 	@Override
 	public TransportId getId() {
 		return TorConstants.ID;
@@ -224,6 +230,7 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 			LOG.warning("Old auth cookie not deleted");
 		// Start a new Tor process
 		LOG.info("Starting Tor");
+		File torFile = getTorExecutableFile();
 		String torPath = torFile.getAbsolutePath();
 		String configPath = configFile.getAbsolutePath();
 		String pid = String.valueOf(getProcessId());
@@ -322,44 +329,43 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 	}
 
 	private void installAssets() throws PluginException {
-		InputStream in = null;
-		OutputStream out = null;
 		try {
 			// The done file may already exist from a previous installation
 			//noinspection ResultOfMethodCallIgnored
 			doneFile.delete();
-			// Unzip the Tor binary to the filesystem
-			in = getTorInputStream();
-			out = new FileOutputStream(torFile);
-			copyAndClose(in, out);
-			// Make the Tor binary executable
-			if (!torFile.setExecutable(true, true)) throw new IOException();
-			// Unzip the GeoIP database to the filesystem
-			in = getGeoIpInputStream();
-			out = new FileOutputStream(geoIpFile);
-			copyAndClose(in, out);
-			// Unzip the Obfs4 proxy to the filesystem
-			in = getObfs4InputStream();
-			out = new FileOutputStream(obfs4File);
-			copyAndClose(in, out);
-			// Make the Obfs4 proxy executable
-			if (!obfs4File.setExecutable(true, true)) throw new IOException();
-			// Copy the config file to the filesystem
-			in = getConfigInputStream();
-			out = new FileOutputStream(configFile);
-			copyAndClose(in, out);
+			installTorExecutable();
+			installObfs4Executable();
+			extract(getGeoIpInputStream(), geoIpFile);
+			extract(getConfigInputStream(), configFile);
 			if (!doneFile.createNewFile())
 				LOG.warning("Failed to create done file");
 		} catch (IOException e) {
-			tryToClose(in, LOG, WARNING);
-			tryToClose(out, LOG, WARNING);
 			throw new PluginException(e);
 		}
 	}
 
-	private InputStream getTorInputStream() throws IOException {
+	protected void extract(InputStream in, File dest) throws IOException {
+		OutputStream out = new FileOutputStream(dest);
+		copyAndClose(in, out);
+	}
+
+	protected void installTorExecutable() throws IOException {
 		if (LOG.isLoggable(INFO))
 			LOG.info("Installing Tor binary for " + architecture);
+		File torFile = getTorExecutableFile();
+		extract(getTorInputStream(), torFile);
+		if (!torFile.setExecutable(true, true)) throw new IOException();
+	}
+
+	protected void installObfs4Executable() throws IOException {
+		if (LOG.isLoggable(INFO))
+			LOG.info("Installing obfs4proxy binary for " + architecture);
+		File obfs4File = getObfs4ExecutableFile();
+		extract(getObfs4InputStream(), obfs4File);
+		if (!obfs4File.setExecutable(true, true)) throw new IOException();
+	}
+
+	private InputStream getTorInputStream() throws IOException {
 		InputStream in = resourceProvider
 				.getResourceInputStream("tor_" + architecture, ".zip");
 		ZipInputStream zin = new ZipInputStream(in);
@@ -376,8 +382,6 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 	}
 
 	private InputStream getObfs4InputStream() throws IOException {
-		if (LOG.isLoggable(INFO))
-			LOG.info("Installing obfs4proxy binary for " + architecture);
 		InputStream in = resourceProvider
 				.getResourceInputStream("obfs4proxy_" + architecture, ".zip");
 		ZipInputStream zin = new ZipInputStream(in);
@@ -569,6 +573,7 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 		if (enable) {
 			Collection<String> conf = new ArrayList<>();
 			conf.add("UseBridges 1");
+			File obfs4File = getObfs4ExecutableFile();
 			if (needsMeek) {
 				conf.add("ClientTransportPlugin meek_lite exec " +
 						obfs4File.getAbsolutePath());

bramble-core/src/main/java/org/briarproject/bramble/sync/validation/ValidationManagerImpl.java

@@ -35,7 +35,6 @@ import java.util.concurrent.Executor;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.logging.Logger;
 
-import javax.annotation.Nullable;
 import javax.annotation.concurrent.ThreadSafe;
 import javax.inject.Inject;
 
@@ -125,7 +124,8 @@ class ValidationManagerImpl implements ValidationManager, Service,
 				Group g = db.getGroup(txn, m.getGroupId());
 				return new Pair<>(m, g);
 			});
-			validateMessageAsync(mg.getFirst(), mg.getSecond(), unvalidated);
+			validateMessageAsync(mg.getFirst(), mg.getSecond());
+			validateNextMessageAsync(unvalidated);
 		} catch (NoSuchMessageException e) {
 			LOG.info("Message removed before validation");
 			validateNextMessageAsync(unvalidated);
@@ -213,14 +213,12 @@ class ValidationManagerImpl implements ValidationManager, Service,
 		}
 	}
 
-	private void validateMessageAsync(Message m, Group g,
-			@Nullable Queue<MessageId> unvalidated) {
-		validationExecutor.execute(() -> validateMessage(m, g, unvalidated));
+	private void validateMessageAsync(Message m, Group g) {
+		validationExecutor.execute(() -> validateMessage(m, g));
 	}
 
 	@ValidationExecutor
-	private void validateMessage(Message m, Group g,
-			@Nullable Queue<MessageId> unvalidated) {
+	private void validateMessage(Message m, Group g) {
 		ClientMajorVersion cv =
 				new ClientMajorVersion(g.getClientId(), g.getMajorVersion());
 		MessageValidator v = validators.get(cv);
@@ -236,8 +234,6 @@ class ValidationManagerImpl implements ValidationManager, Service,
 				Queue<MessageId> invalidate = new LinkedList<>();
 				invalidate.add(m.getId());
 				invalidateNextMessageAsync(invalidate);
-			} finally {
-				if (unvalidated != null) validateNextMessageAsync(unvalidated);
 			}
 		}
 	}
@@ -444,7 +440,7 @@ class ValidationManagerImpl implements ValidationManager, Service,
 		try {
 			Group g = db.transactionWithResult(true, txn ->
 					db.getGroup(txn, m.getGroupId()));
-			validateMessageAsync(m, g, null);
+			validateMessageAsync(m, g);
 		} catch (NoSuchGroupException e) {
 			LOG.info("Group removed before validation");
 		} catch (DbException e) {

bramble-core/src/test/java/org/briarproject/bramble/test/TestDuplexTransportConnection.java

@@ -43,6 +43,15 @@ public class TestDuplexTransportConnection
 		return new TransportProperties();
 	}
 
+	@Override
+	public boolean isMarkedForClose() {
+		return false;
+	}
+
+	@Override
+	public void markForClose() {
+	}
+
 	/**
 	 * Creates and returns a pair of TestDuplexTransportConnections that are
 	 * connected to each other.

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

@@ -65,7 +65,7 @@ public class JavaBluetoothPluginFactory implements DuplexPluginFactory {
 	@Override
 	public DuplexPlugin createPlugin(PluginCallback callback) {
 		BluetoothConnectionLimiter connectionLimiter =
-				new BluetoothConnectionLimiterImpl(eventBus);
+				new BluetoothConnectionLimiterImpl(eventBus, false);
 		BluetoothConnectionFactory<StreamConnection> connectionFactory =
 				new JavaBluetoothConnectionFactory(connectionLimiter,
 						timeoutMonitor);

briar-android/build.gradle

@@ -16,14 +16,14 @@ def getStdout = { command, defaultValue ->
 }
 
 android {
-	compileSdkVersion 29
-	buildToolsVersion '29.0.2'
+	compileSdkVersion rootProject.ext.compileSdkVersion
+	buildToolsVersion rootProject.ext.buildToolsVersion
 
 	defaultConfig {
-		minSdkVersion 16
-		targetSdkVersion 28
-		versionCode 10209
-		versionName "1.2.9"
+		minSdkVersion rootProject.ext.minSdkVersion
+		targetSdkVersion rootProject.ext.targetSdkVersion
+		versionCode rootProject.ext.versionCode
+		versionName rootProject.ext.versionName
 		applicationId "org.briarproject.briar.android"
 		buildConfigField "String", "GitHash",
 				"\"${getStdout(['git', 'rev-parse', '--short=7', 'HEAD'], 'No commit hash')}\""

briar-android/src/androidTestOfficial/java/org/briarproject/briar/android/attachment/AttachmentRetrieverIntegrationTest.java

@@ -13,8 +13,9 @@ import java.util.Random;
 import androidx.test.ext.junit.runners.AndroidJUnit4;
 
 import static androidx.test.InstrumentationRegistry.getContext;
+import static org.briarproject.briar.android.attachment.AttachmentItem.State.AVAILABLE;
+import static org.briarproject.briar.android.attachment.AttachmentItem.State.ERROR;
 import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
 
 @RunWith(AndroidJUnit4.class)
@@ -27,7 +28,7 @@ public class AttachmentRetrieverIntegrationTest {
 
 	private final ImageHelper imageHelper = new ImageHelperImpl();
 	private final AttachmentRetriever retriever =
-			new AttachmentRetrieverImpl(null, dimensions, imageHelper,
+			new AttachmentRetrieverImpl(null, null, dimensions, imageHelper,
 					new ImageSizeCalculator(imageHelper));
 
 	@Test
@@ -35,7 +36,7 @@ public class AttachmentRetrieverIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/jpeg");
 		InputStream is = getAssetInputStream("kitten_small.jpg");
 		Attachment a = new Attachment(h, is);
-		AttachmentItem item = retriever.getAttachmentItem(a, true);
+		AttachmentItem item = retriever.createAttachmentItem(a, true);
 		assertEquals(msgId, item.getMessageId());
 		assertEquals(160, item.getWidth());
 		assertEquals(240, item.getHeight());
@@ -43,7 +44,7 @@ public class AttachmentRetrieverIntegrationTest {
 		assertEquals(240, item.getThumbnailHeight());
 		assertEquals("image/jpeg", item.getMimeType());
 		assertJpgOrJpeg(item.getExtension());
-		assertFalse(item.hasError());
+		assertEquals(AVAILABLE, item.getState());
 	}
 
 	@Test
@@ -51,7 +52,7 @@ public class AttachmentRetrieverIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/jpeg");
 		InputStream is = getAssetInputStream("kitten_original.jpg");
 		Attachment a = new Attachment(h, is);
-		AttachmentItem item = retriever.getAttachmentItem(a, true);
+		AttachmentItem item = retriever.createAttachmentItem(a, true);
 		assertEquals(msgId, item.getMessageId());
 		assertEquals(1728, item.getWidth());
 		assertEquals(2592, item.getHeight());
@@ -59,7 +60,7 @@ public class AttachmentRetrieverIntegrationTest {
 		assertEquals(dimensions.maxHeight, item.getThumbnailHeight());
 		assertEquals("image/jpeg", item.getMimeType());
 		assertJpgOrJpeg(item.getExtension());
-		assertFalse(item.hasError());
+		assertEquals(AVAILABLE, item.getState());
 	}
 
 	@Test
@@ -67,7 +68,7 @@ public class AttachmentRetrieverIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/png");
 		InputStream is = getAssetInputStream("kitten.png");
 		Attachment a = new Attachment(h, is);
-		AttachmentItem item = retriever.getAttachmentItem(a, true);
+		AttachmentItem item = retriever.createAttachmentItem(a, true);
 		assertEquals(msgId, item.getMessageId());
 		assertEquals(737, item.getWidth());
 		assertEquals(510, item.getHeight());
@@ -75,7 +76,7 @@ public class AttachmentRetrieverIntegrationTest {
 		assertEquals(138, item.getThumbnailHeight());
 		assertEquals("image/png", item.getMimeType());
 		assertEquals("png", item.getExtension());
-		assertFalse(item.hasError());
+		assertEquals(AVAILABLE, item.getState());
 	}
 
 	@Test
@@ -83,14 +84,14 @@ public class AttachmentRetrieverIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/gif");
 		InputStream is = getAssetInputStream("uber.gif");
 		Attachment a = new Attachment(h, is);
-		AttachmentItem item = retriever.getAttachmentItem(a, true);
+		AttachmentItem item = retriever.createAttachmentItem(a, true);
 		assertEquals(1, item.getWidth());
 		assertEquals(1, item.getHeight());
 		assertEquals(dimensions.minHeight, item.getThumbnailWidth());
 		assertEquals(dimensions.minHeight, item.getThumbnailHeight());
 		assertEquals("image/gif", item.getMimeType());
 		assertEquals("gif", item.getExtension());
-		assertFalse(item.hasError());
+		assertEquals(AVAILABLE, item.getState());
 	}
 
 	@Test
@@ -98,14 +99,14 @@ public class AttachmentRetrieverIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/jpeg");
 		InputStream is = getAssetInputStream("lottapixel.jpg");
 		Attachment a = new Attachment(h, is);
-		AttachmentItem item = retriever.getAttachmentItem(a, true);
+		AttachmentItem item = retriever.createAttachmentItem(a, true);
 		assertEquals(64250, item.getWidth());
 		assertEquals(64250, item.getHeight());
 		assertEquals(dimensions.maxWidth, item.getThumbnailWidth());
 		assertEquals(dimensions.maxWidth, item.getThumbnailHeight());
 		assertEquals("image/jpeg", item.getMimeType());
 		assertJpgOrJpeg(item.getExtension());
-		assertFalse(item.hasError());
+		assertEquals(AVAILABLE, item.getState());
 	}
 
 	@Test
@@ -113,14 +114,14 @@ public class AttachmentRetrieverIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/png");
 		InputStream is = getAssetInputStream("image_io_crash.png");
 		Attachment a = new Attachment(h, is);
-		AttachmentItem item = retriever.getAttachmentItem(a, true);
+		AttachmentItem item = retriever.createAttachmentItem(a, true);
 		assertEquals(1184, item.getWidth());
 		assertEquals(448, item.getHeight());
 		assertEquals(dimensions.maxWidth, item.getThumbnailWidth());
 		assertEquals(dimensions.minHeight, item.getThumbnailHeight());
 		assertEquals("image/png", item.getMimeType());
 		assertEquals("png", item.getExtension());
-		assertFalse(item.hasError());
+		assertEquals(AVAILABLE, item.getState());
 	}
 
 	@Test
@@ -128,14 +129,14 @@ public class AttachmentRetrieverIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/gif");
 		InputStream is = getAssetInputStream("gimp_crash.gif");
 		Attachment a = new Attachment(h, is);
-		AttachmentItem item = retriever.getAttachmentItem(a, true);
+		AttachmentItem item = retriever.createAttachmentItem(a, true);
 		assertEquals(1, item.getWidth());
 		assertEquals(1, item.getHeight());
 		assertEquals(dimensions.minHeight, item.getThumbnailWidth());
 		assertEquals(dimensions.minHeight, item.getThumbnailHeight());
 		assertEquals("image/gif", item.getMimeType());
 		assertEquals("gif", item.getExtension());
-		assertFalse(item.hasError());
+		assertEquals(AVAILABLE, item.getState());
 	}
 
 	@Test
@@ -143,14 +144,14 @@ public class AttachmentRetrieverIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/gif");
 		InputStream is = getAssetInputStream("opti_png_afl.gif");
 		Attachment a = new Attachment(h, is);
-		AttachmentItem item = retriever.getAttachmentItem(a, true);
+		AttachmentItem item = retriever.createAttachmentItem(a, true);
 		assertEquals(32, item.getWidth());
 		assertEquals(32, item.getHeight());
 		assertEquals(dimensions.minHeight, item.getThumbnailWidth());
 		assertEquals(dimensions.minHeight, item.getThumbnailHeight());
 		assertEquals("image/gif", item.getMimeType());
 		assertEquals("gif", item.getExtension());
-		assertFalse(item.hasError());
+		assertEquals(AVAILABLE, item.getState());
 	}
 
 	@Test
@@ -158,8 +159,8 @@ public class AttachmentRetrieverIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/jpeg");
 		InputStream is = getAssetInputStream("libraw_error.jpg");
 		Attachment a = new Attachment(h, is);
-		AttachmentItem item = retriever.getAttachmentItem(a, true);
-		assertTrue(item.hasError());
+		AttachmentItem item = retriever.createAttachmentItem(a, true);
+		assertEquals(ERROR, item.getState());
 	}
 
 	@Test
@@ -167,14 +168,14 @@ public class AttachmentRetrieverIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/gif");
 		InputStream is = getAssetInputStream("animated.gif");
 		Attachment a = new Attachment(h, is);
-		AttachmentItem item = retriever.getAttachmentItem(a, true);
+		AttachmentItem item = retriever.createAttachmentItem(a, true);
 		assertEquals(65535, item.getWidth());
 		assertEquals(65535, item.getHeight());
 		assertEquals(dimensions.maxWidth, item.getThumbnailWidth());
 		assertEquals(dimensions.maxWidth, item.getThumbnailHeight());
 		assertEquals("image/gif", item.getMimeType());
 		assertEquals("gif", item.getExtension());
-		assertFalse(item.hasError());
+		assertEquals(AVAILABLE, item.getState());
 	}
 
 	@Test
@@ -182,14 +183,14 @@ public class AttachmentRetrieverIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/gif");
 		InputStream is = getAssetInputStream("animated2.gif");
 		Attachment a = new Attachment(h, is);
-		AttachmentItem item = retriever.getAttachmentItem(a, true);
+		AttachmentItem item = retriever.createAttachmentItem(a, true);
 		assertEquals(10000, item.getWidth());
 		assertEquals(10000, item.getHeight());
 		assertEquals(dimensions.maxWidth, item.getThumbnailWidth());
 		assertEquals(dimensions.maxWidth, item.getThumbnailHeight());
 		assertEquals("image/gif", item.getMimeType());
 		assertEquals("gif", item.getExtension());
-		assertFalse(item.hasError());
+		assertEquals(AVAILABLE, item.getState());
 	}
 
 	@Test
@@ -197,14 +198,14 @@ public class AttachmentRetrieverIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/gif");
 		InputStream is = getAssetInputStream("error_large.gif");
 		Attachment a = new Attachment(h, is);
-		AttachmentItem item = retriever.getAttachmentItem(a, true);
+		AttachmentItem item = retriever.createAttachmentItem(a, true);
 		assertEquals(16384, item.getWidth());
 		assertEquals(16384, item.getHeight());
 		assertEquals(dimensions.maxWidth, item.getThumbnailWidth());
 		assertEquals(dimensions.maxWidth, item.getThumbnailHeight());
 		assertEquals("image/gif", item.getMimeType());
 		assertEquals("gif", item.getExtension());
-		assertFalse(item.hasError());
+		assertEquals(AVAILABLE, item.getState());
 	}
 
 	@Test
@@ -212,14 +213,14 @@ public class AttachmentRetrieverIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/jpeg");
 		InputStream is = getAssetInputStream("error_high.jpg");
 		Attachment a = new Attachment(h, is);
-		AttachmentItem item = retriever.getAttachmentItem(a, true);
+		AttachmentItem item = retriever.createAttachmentItem(a, true);
 		assertEquals(1, item.getWidth());
 		assertEquals(10000, item.getHeight());
 		assertEquals(dimensions.minWidth, item.getThumbnailWidth());
 		assertEquals(dimensions.maxHeight, item.getThumbnailHeight());
 		assertEquals("image/jpeg", item.getMimeType());
 		assertJpgOrJpeg(item.getExtension());
-		assertFalse(item.hasError());
+		assertEquals(AVAILABLE, item.getState());
 	}
 
 	@Test
@@ -227,14 +228,14 @@ public class AttachmentRetrieverIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/jpeg");
 		InputStream is = getAssetInputStream("error_wide.jpg");
 		Attachment a = new Attachment(h, is);
-		AttachmentItem item = retriever.getAttachmentItem(a, true);
+		AttachmentItem item = retriever.createAttachmentItem(a, true);
 		assertEquals(1920, item.getWidth());
 		assertEquals(1, item.getHeight());
 		assertEquals(dimensions.maxWidth, item.getThumbnailWidth());
 		assertEquals(dimensions.minHeight, item.getThumbnailHeight());
 		assertEquals("image/jpeg", item.getMimeType());
 		assertJpgOrJpeg(item.getExtension());
-		assertFalse(item.hasError());
+		assertEquals(AVAILABLE, item.getState());
 	}
 
 	private InputStream getAssetInputStream(String name) throws Exception {

briar-android/src/main/java/org/briarproject/briar/android/attachment/AttachmentCreatorImpl.java

@@ -34,6 +34,7 @@ import androidx.lifecycle.MutableLiveData;
 import static java.util.logging.Level.WARNING;
 import static java.util.logging.Logger.getLogger;
 import static org.briarproject.bramble.util.LogUtils.logException;
+import static org.briarproject.briar.android.attachment.AttachmentItem.State.ERROR;
 import static org.briarproject.briar.android.util.UiUtils.observeForeverOnce;
 import static org.briarproject.briar.api.messaging.MessagingConstants.MAX_IMAGE_SIZE;
 
@@ -75,8 +76,12 @@ class AttachmentCreatorImpl implements AttachmentCreator {
 	@UiThread
 	public LiveData<AttachmentResult> storeAttachments(
 			LiveData<GroupId> groupId, Collection<Uri> newUris) {
-		if (task != null || result != null || !uris.isEmpty())
+		if (task != null || result != null || !uris.isEmpty()) {
+			if (task != null) LOG.warning("Task already exists!");
+			if (result != null) LOG.warning("Result already exists!");
+			if (!uris.isEmpty()) LOG.warning("Uris available: " + uris);
 			throw new IllegalStateException();
+		}
 		MutableLiveData<AttachmentResult> result = new MutableLiveData<>();
 		this.result = result;
 		uris.addAll(newUris);
@@ -95,8 +100,12 @@ class AttachmentCreatorImpl implements AttachmentCreator {
 	@UiThread
 	public LiveData<AttachmentResult> getLiveAttachments() {
 		MutableLiveData<AttachmentResult> result = this.result;
-		if (task == null || result == null || uris.isEmpty())
+		if (task == null || result == null || uris.isEmpty()) {
+			if (task == null) LOG.warning("No Task!");
+			if (result == null) LOG.warning("No Result!");
+			if (uris.isEmpty()) LOG.warning("Uris empty!");
 			throw new IllegalStateException();
+		}
 		// A task is already running. It will update the result LiveData.
 		// So nothing more to do here.
 		return result;
@@ -109,8 +118,8 @@ class AttachmentCreatorImpl implements AttachmentCreator {
 		// get and cache AttachmentItem for ImagePreview
 		try {
 			Attachment a = retriever.getMessageAttachment(h);
-			AttachmentItem item = retriever.getAttachmentItem(a, needsSize);
-			if (item.hasError()) throw new IOException();
+			AttachmentItem item = retriever.createAttachmentItem(a, needsSize);
+			if (item.getState() == ERROR) throw new IOException();
 			AttachmentItemResult itemResult =
 					new AttachmentItemResult(uri, item);
 			itemResults.add(itemResult);
@@ -167,21 +176,13 @@ class AttachmentCreatorImpl implements AttachmentCreator {
 	@Override
 	@UiThread
 	public void onAttachmentsSent(MessageId id) {
-		List<AttachmentItem> items = new ArrayList<>(itemResults.size());
-		for (AttachmentItemResult itemResult : itemResults) {
-			// check if we are trying to send attachment items with errors
-			if (itemResult.getItem() == null) throw new IllegalStateException();
-			items.add(itemResult.getItem());
-		}
-		retriever.cachePut(id, items);
 		resetState();
 	}
 
 	@Override
 	@UiThread
 	public void cancel() {
-		if (task == null) throw new AssertionError();
-		task.cancel();
+		if (task != null) task.cancel();
 		deleteUnsentAttachments();
 		resetState();
 	}

briar-android/src/main/java/org/briarproject/briar/android/attachment/AttachmentItem.java

@@ -7,24 +7,33 @@ import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.briar.api.messaging.AttachmentHeader;
 
-import java.util.concurrent.atomic.AtomicLong;
-
 import javax.annotation.concurrent.Immutable;
 
 import androidx.annotation.Nullable;
 
+import static java.lang.System.arraycopy;
 import static java.util.Objects.requireNonNull;
+import static org.briarproject.bramble.util.StringUtils.toHexString;
+import static org.briarproject.briar.android.attachment.AttachmentItem.State.LOADING;
+import static org.briarproject.briar.android.attachment.AttachmentItem.State.MISSING;
 
 @Immutable
 @NotNullByDefault
 public class AttachmentItem implements Parcelable {
 
+	public enum State {
+		LOADING, MISSING, AVAILABLE, ERROR;
+
+		public boolean isFinal() {
+			return this == AVAILABLE || this == ERROR;
+		}
+	}
+
 	private final AttachmentHeader header;
 	private final int width, height;
 	private final String extension;
 	private final int thumbnailWidth, thumbnailHeight;
-	private final boolean hasError;
-	private final long instanceId;
+	private final State state;
 
 	public static final Creator<AttachmentItem> CREATOR =
 			new Creator<AttachmentItem>() {
@@ -39,19 +48,33 @@ public class AttachmentItem implements Parcelable {
 				}
 			};
 
-	private static final AtomicLong NEXT_INSTANCE_ID = new AtomicLong(0);
-
 	AttachmentItem(AttachmentHeader header, int width, int height,
 			String extension, int thumbnailWidth, int thumbnailHeight,
-			boolean hasError) {
+			State state) {
 		this.header = header;
 		this.width = width;
 		this.height = height;
 		this.extension = extension;
 		this.thumbnailWidth = thumbnailWidth;
 		this.thumbnailHeight = thumbnailHeight;
-		this.hasError = hasError;
-		instanceId = NEXT_INSTANCE_ID.getAndIncrement();
+		this.state = state;
+	}
+
+	/**
+	 * Use only for {@link State MISSING} or {@link State LOADING} items.
+	 */
+	AttachmentItem(AttachmentHeader header, int width, int height,
+			State state) {
+		this(header, width, height, "", width, height, state);
+		if (state != MISSING && state != LOADING)
+			throw new IllegalArgumentException();
+	}
+
+	/**
+	 * Use when the item does not need a size.
+	 */
+	AttachmentItem(AttachmentHeader header, String extension, State state) {
+		this(header, 0, 0, extension, 0, 0, state);
 	}
 
 	protected AttachmentItem(Parcel in) {
@@ -64,8 +87,7 @@ public class AttachmentItem implements Parcelable {
 		extension = requireNonNull(in.readString());
 		thumbnailWidth = in.readInt();
 		thumbnailHeight = in.readInt();
-		hasError = in.readByte() != 0;
-		instanceId = in.readLong();
+		state = State.valueOf(requireNonNull(in.readString()));
 		header = new AttachmentHeader(messageId, mimeType);
 	}
 
@@ -101,12 +123,16 @@ public class AttachmentItem implements Parcelable {
 		return thumbnailHeight;
 	}
 
-	public boolean hasError() {
-		return hasError;
+	public State getState() {
+		return state;
 	}
 
-	public String getTransitionName() {
-		return String.valueOf(instanceId);
+	public String getTransitionName(MessageId conversationItemId) {
+		int len = MessageId.LENGTH;
+		byte[] instanceId = new byte[len * 2];
+		arraycopy(header.getMessageId().getBytes(), 0, instanceId, 0, len);
+		arraycopy(conversationItemId.getBytes(), 0, instanceId, len, len);
+		return toHexString(instanceId);
 	}
 
 	@Override
@@ -123,14 +149,23 @@ public class AttachmentItem implements Parcelable {
 		dest.writeString(extension);
 		dest.writeInt(thumbnailWidth);
 		dest.writeInt(thumbnailHeight);
-		dest.writeByte((byte) (hasError ? 1 : 0));
-		dest.writeLong(instanceId);
+		dest.writeString(state.name());
 	}
 
+	/**
+	 * This is used to identity if two items are the same,
+	 * irrespective of their state or size.
+	 */
 	@Override
 	public boolean equals(@Nullable Object o) {
 		return o instanceof AttachmentItem &&
-				instanceId == ((AttachmentItem) o).instanceId;
+				header.getMessageId().equals(
+						((AttachmentItem) o).header.getMessageId()
+				);
 	}
 
+	@Override
+	public int hashCode() {
+		return header.getMessageId().hashCode();
+	}
 }

briar-android/src/main/java/org/briarproject/briar/android/attachment/AttachmentRetriever.java

@@ -1,29 +1,63 @@
 package org.briarproject.briar.android.attachment;
 
+import org.briarproject.bramble.api.db.DatabaseExecutor;
 import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.briar.api.messaging.Attachment;
 import org.briarproject.briar.api.messaging.AttachmentHeader;
+import org.briarproject.briar.api.messaging.PrivateMessageHeader;
+import org.briarproject.briar.api.messaging.event.AttachmentReceivedEvent;
 
 import java.io.InputStream;
 import java.util.List;
 
-import androidx.annotation.Nullable;
+import androidx.lifecycle.LiveData;
+
 
 @NotNullByDefault
 public interface AttachmentRetriever {
 
-	void cachePut(MessageId messageId, List<AttachmentItem> attachments);
-
-	@Nullable
-	List<AttachmentItem> cacheGet(MessageId messageId);
-
+	@DatabaseExecutor
 	Attachment getMessageAttachment(AttachmentHeader h) throws DbException;
 
+	/**
+	 * Returns a list of observable {@link LiveData}
+	 * that get updated as the state of their {@link AttachmentItem}s changes.
+	 */
+	List<LiveData<AttachmentItem>> getAttachmentItems(
+			PrivateMessageHeader messageHeader);
+
+	/**
+	 * Retrieves item size and adds the item to the cache, if available.
+	 * <p>
+	 * Use this to eagerly load the attachment size before it gets displayed.
+	 * This is needed for messages containing a single attachment.
+	 * Messages with more than one attachment use a standard size.
+	 */
+	@DatabaseExecutor
+	void cacheAttachmentItemWithSize(MessageId conversationMessageId,
+			AttachmentHeader h) throws DbException;
+
 	/**
 	 * Creates an {@link AttachmentItem} from the {@link Attachment}'s
 	 * {@link InputStream} which will be closed when this method returns.
 	 */
-	AttachmentItem getAttachmentItem(Attachment a, boolean needsSize);
+	AttachmentItem createAttachmentItem(Attachment a, boolean needsSize);
+
+	/**
+	 * Loads an {@link AttachmentItem}
+	 * that arrived via an {@link AttachmentReceivedEvent}
+	 * and notifies the associated {@link LiveData}.
+	 *
+	 * Note that you need to call {@link #getAttachmentItems(PrivateMessageHeader)}
+	 * first to get the LiveData.
+	 *
+	 * It is possible that no LiveData is available,
+	 * because the message of the AttachmentItem did not arrive, yet.
+	 * In this case, the load wil be deferred until the message arrives.
+	 */
+	@DatabaseExecutor
+	void loadAttachmentItem(MessageId attachmentId);
+
 }

briar-android/src/main/java/org/briarproject/briar/android/attachment/AttachmentRetrieverImpl.java

@@ -1,25 +1,39 @@
 package org.briarproject.briar.android.attachment;
 
+import org.briarproject.bramble.api.db.DatabaseExecutor;
 import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.db.NoSuchMessageException;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.sync.MessageId;
+import org.briarproject.briar.android.attachment.AttachmentItem.State;
 import org.briarproject.briar.api.messaging.Attachment;
 import org.briarproject.briar.api.messaging.AttachmentHeader;
 import org.briarproject.briar.api.messaging.MessagingManager;
+import org.briarproject.briar.api.messaging.PrivateMessageHeader;
 
 import java.io.BufferedInputStream;
 import java.io.InputStream;
+import java.util.ArrayList;
 import java.util.List;
-import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentMap;
+import java.util.concurrent.Executor;
 import java.util.logging.Logger;
 
 import javax.inject.Inject;
 
-import androidx.annotation.Nullable;
+import androidx.lifecycle.LiveData;
+import androidx.lifecycle.MutableLiveData;
 
+import static java.util.Objects.requireNonNull;
 import static java.util.logging.Level.WARNING;
 import static java.util.logging.Logger.getLogger;
+import static org.briarproject.bramble.util.IoUtils.tryToClose;
+import static org.briarproject.bramble.util.LogUtils.logException;
+import static org.briarproject.briar.android.attachment.AttachmentItem.State.AVAILABLE;
+import static org.briarproject.briar.android.attachment.AttachmentItem.State.ERROR;
+import static org.briarproject.briar.android.attachment.AttachmentItem.State.LOADING;
+import static org.briarproject.briar.android.attachment.AttachmentItem.State.MISSING;
 
 @NotNullByDefault
 class AttachmentRetrieverImpl implements AttachmentRetriever {
@@ -27,6 +41,8 @@ class AttachmentRetrieverImpl implements AttachmentRetriever {
 	private static final Logger LOG =
 			getLogger(AttachmentRetrieverImpl.class.getName());
 
+	@DatabaseExecutor
+	private final Executor dbExecutor;
 	private final MessagingManager messagingManager;
 	private final ImageHelper imageHelper;
 	private final ImageSizeCalculator imageSizeCalculator;
@@ -34,13 +50,17 @@ class AttachmentRetrieverImpl implements AttachmentRetriever {
 	private final int minWidth, maxWidth;
 	private final int minHeight, maxHeight;
 
-	private final Map<MessageId, List<AttachmentItem>> attachmentCache =
-			new ConcurrentHashMap<>();
+	private final ConcurrentMap<MessageId, MutableLiveData<AttachmentItem>>
+			itemsWithSize = new ConcurrentHashMap<>();
+	private final ConcurrentMap<MessageId, MutableLiveData<AttachmentItem>>
+			itemsWithoutSize = new ConcurrentHashMap<>();
 
 	@Inject
-	AttachmentRetrieverImpl(MessagingManager messagingManager,
+	AttachmentRetrieverImpl(@DatabaseExecutor Executor dbExecutor,
+			MessagingManager messagingManager,
 			AttachmentDimensions dimensions, ImageHelper imageHelper,
 			ImageSizeCalculator imageSizeCalculator) {
+		this.dbExecutor = dbExecutor;
 		this.messagingManager = messagingManager;
 		this.imageHelper = imageHelper;
 		this.imageSizeCalculator = imageSizeCalculator;
@@ -52,40 +72,143 @@ class AttachmentRetrieverImpl implements AttachmentRetriever {
 	}
 
 	@Override
-	public void cachePut(MessageId messageId,
-			List<AttachmentItem> attachments) {
-		attachmentCache.put(messageId, attachments);
-	}
-
-	@Override
-	@Nullable
-	public List<AttachmentItem> cacheGet(MessageId messageId) {
-		return attachmentCache.get(messageId);
-	}
-
-	@Override
+	@DatabaseExecutor
 	public Attachment getMessageAttachment(AttachmentHeader h)
 			throws DbException {
 		return messagingManager.getAttachment(h);
 	}
 
 	@Override
-	public AttachmentItem getAttachmentItem(Attachment a, boolean needsSize) {
-		AttachmentHeader h = a.getHeader();
-		if (!needsSize) {
-			String extension =
-					imageHelper.getExtensionFromMimeType(h.getContentType());
-			boolean hasError = false;
-			if (extension == null) {
-				extension = "";
-				hasError = true;
+	public List<LiveData<AttachmentItem>> getAttachmentItems(
+			PrivateMessageHeader messageHeader) {
+		List<AttachmentHeader> headers = messageHeader.getAttachmentHeaders();
+		List<LiveData<AttachmentItem>> items = new ArrayList<>(headers.size());
+		boolean needsSize = headers.size() == 1;
+		for (AttachmentHeader h : headers) {
+			// try cache for existing item live data
+			MutableLiveData<AttachmentItem> liveData;
+			if (needsSize) liveData = itemsWithSize.get(h.getMessageId());
+			else {
+				// try items with size first, as they work as well
+				liveData = itemsWithSize.get(h.getMessageId());
+				if (liveData == null)
+					liveData = itemsWithoutSize.get(h.getMessageId());
 			}
-			return new AttachmentItem(h, 0, 0, extension, 0, 0, hasError);
+
+			// create new live data with LOADING item if cache miss
+			if (liveData == null) {
+				AttachmentItem item = new AttachmentItem(h,
+						defaultSize, defaultSize, LOADING);
+				liveData = new MutableLiveData<>(item);
+				// add new LiveData to cache, checking for concurrent updates
+				MutableLiveData<AttachmentItem> oldLiveData;
+				if (needsSize) {
+					oldLiveData = itemsWithSize.putIfAbsent(h.getMessageId(),
+							liveData);
+				} else {
+					oldLiveData = itemsWithoutSize.putIfAbsent(h.getMessageId(),
+							liveData);
+				}
+				if (oldLiveData == null) {
+					// kick-off loading of attachment, will post to live data
+					MutableLiveData<AttachmentItem> finalLiveData = liveData;
+					dbExecutor.execute(() ->
+							loadAttachmentItem(h, needsSize, finalLiveData));
+				} else {
+					// Concurrent cache update - use the existing live data
+					liveData = oldLiveData;
+				}
+			}
+			items.add(liveData);
+		}
+		return items;
+	}
+
+	@Override
+	@DatabaseExecutor
+	public void cacheAttachmentItemWithSize(MessageId conversationMessageId,
+			AttachmentHeader h) throws DbException {
+		// If a live data is already cached we don't need to do anything
+		if (itemsWithSize.containsKey(h.getMessageId())) return;
+		try {
+			Attachment a = messagingManager.getAttachment(h);
+			AttachmentItem item = createAttachmentItem(a, true);
+			MutableLiveData<AttachmentItem> liveData =
+					new MutableLiveData<>(item);
+			// If a live data was concurrently cached, don't replace it
+			itemsWithSize.putIfAbsent(h.getMessageId(), liveData);
+		} catch (NoSuchMessageException e) {
+			LOG.info("Attachment not received yet");
+		}
+	}
+
+	@Override
+	@DatabaseExecutor
+	public void loadAttachmentItem(MessageId attachmentId) {
+		// try to find LiveData for attachment in both caches
+		MutableLiveData<AttachmentItem> liveData;
+		boolean needsSize = true;
+		liveData = itemsWithSize.get(attachmentId);
+		if (liveData == null) {
+			needsSize = false;
+			liveData = itemsWithoutSize.get(attachmentId);
 		}
 
-		InputStream is = new BufferedInputStream(a.getStream());
-		Size size = imageSizeCalculator.getSize(is, h.getContentType());
+		// If no LiveData for the attachment exists,
+		// its message did not yet arrive and we can ignore it for now.
+		if (liveData == null) return;
 
+		// actually load the attachment item
+		AttachmentHeader h = requireNonNull(liveData.getValue()).getHeader();
+		loadAttachmentItem(h, needsSize, liveData);
+	}
+
+	/**
+	 * Loads an {@link AttachmentItem} from the database
+	 * and notifies the given {@link LiveData}.
+	 */
+	@DatabaseExecutor
+	private void loadAttachmentItem(AttachmentHeader h, boolean needsSize,
+			MutableLiveData<AttachmentItem> liveData) {
+		Attachment a;
+		AttachmentItem item;
+		try {
+			a = messagingManager.getAttachment(h);
+			item = createAttachmentItem(a, needsSize);
+		} catch (NoSuchMessageException e) {
+			LOG.info("Attachment not received yet");
+			item = new AttachmentItem(h, defaultSize, defaultSize, MISSING);
+		} catch (DbException e) {
+			logException(LOG, WARNING, e);
+			item = new AttachmentItem(h, "", ERROR);
+		}
+		liveData.postValue(item);
+	}
+
+	@Override
+	public AttachmentItem createAttachmentItem(Attachment a,
+			boolean needsSize) {
+		AttachmentItem item;
+		AttachmentHeader h = a.getHeader();
+		if (needsSize) {
+			InputStream is = new BufferedInputStream(a.getStream());
+			Size size = imageSizeCalculator.getSize(is, h.getContentType());
+			tryToClose(is, LOG, WARNING);
+			item = createAttachmentItem(h, size);
+		} else {
+			String extension =
+					imageHelper.getExtensionFromMimeType(h.getContentType());
+			State state = AVAILABLE;
+			if (extension == null) {
+				extension = "";
+				state = ERROR;
+			}
+			item = new AttachmentItem(h, extension, state);
+		}
+		return item;
+	}
+
+	private AttachmentItem createAttachmentItem(AttachmentHeader h, Size size) {
 		// calculate thumbnail size
 		Size thumbnailSize = new Size(defaultSize, defaultSize, size.mimeType);
 		if (!size.error) {
@@ -104,8 +227,9 @@ class AttachmentRetrieverImpl implements AttachmentRetriever {
 			hasError = true;
 		}
 		if (extension == null) extension = "";
-		return new AttachmentItem(h, size.width, size.height, extension,
-				thumbnailSize.width, thumbnailSize.height, hasError);
+		State state = hasError ? ERROR : AVAILABLE;
+		return new AttachmentItem(h, size.width, size.height,
+				extension, thumbnailSize.width, thumbnailSize.height, state);
 	}
 
 	private Size getThumbnailSize(int width, int height, String mimeType) {

briar-android/src/main/java/org/briarproject/briar/android/conversation/ConversationActivity.java

@@ -28,7 +28,6 @@ import org.briarproject.bramble.api.contact.event.ContactRemovedEvent;
 import org.briarproject.bramble.api.db.DatabaseExecutor;
 import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.db.NoSuchContactException;
-import org.briarproject.bramble.api.db.NoSuchMessageException;
 import org.briarproject.bramble.api.event.Event;
 import org.briarproject.bramble.api.event.EventBus;
 import org.briarproject.bramble.api.event.EventListener;
@@ -65,17 +64,16 @@ import org.briarproject.briar.api.client.ProtocolStateException;
 import org.briarproject.briar.api.client.SessionId;
 import org.briarproject.briar.api.conversation.ConversationManager;
 import org.briarproject.briar.api.conversation.ConversationMessageHeader;
+import org.briarproject.briar.api.conversation.ConversationMessageVisitor;
 import org.briarproject.briar.api.conversation.ConversationRequest;
 import org.briarproject.briar.api.conversation.ConversationResponse;
 import org.briarproject.briar.api.conversation.DeletionResult;
 import org.briarproject.briar.api.conversation.event.ConversationMessageReceivedEvent;
 import org.briarproject.briar.api.forum.ForumSharingManager;
 import org.briarproject.briar.api.introduction.IntroductionManager;
-import org.briarproject.briar.api.messaging.Attachment;
 import org.briarproject.briar.api.messaging.AttachmentHeader;
 import org.briarproject.briar.api.messaging.MessagingManager;
 import org.briarproject.briar.api.messaging.PrivateMessageHeader;
-import org.briarproject.briar.api.messaging.event.AttachmentReceivedEvent;
 import org.briarproject.briar.api.privategroup.invitation.GroupInvitationManager;
 
 import java.util.ArrayList;
@@ -97,6 +95,7 @@ import androidx.appcompat.widget.Toolbar;
 import androidx.core.app.ActivityCompat;
 import androidx.core.app.ActivityOptionsCompat;
 import androidx.core.content.ContextCompat;
+import androidx.lifecycle.LiveData;
 import androidx.lifecycle.Observer;
 import androidx.lifecycle.ViewModelProvider;
 import androidx.lifecycle.ViewModelProviders;
@@ -118,8 +117,6 @@ import static androidx.core.app.ActivityOptionsCompat.makeSceneTransitionAnimati
 import static androidx.core.view.ViewCompat.setTransitionName;
 import static androidx.lifecycle.Lifecycle.State.STARTED;
 import static androidx.recyclerview.widget.SortedList.INVALID_POSITION;
-import static java.util.Collections.emptyList;
-import static java.util.Collections.singletonList;
 import static java.util.Collections.sort;
 import static java.util.Objects.requireNonNull;
 import static java.util.logging.Level.INFO;
@@ -136,6 +133,7 @@ import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_INTRO
 import static org.briarproject.briar.android.conversation.ImageActivity.ATTACHMENTS;
 import static org.briarproject.briar.android.conversation.ImageActivity.ATTACHMENT_POSITION;
 import static org.briarproject.briar.android.conversation.ImageActivity.DATE;
+import static org.briarproject.briar.android.conversation.ImageActivity.ITEM_ID;
 import static org.briarproject.briar.android.conversation.ImageActivity.NAME;
 import static org.briarproject.briar.android.util.UiUtils.getAvatarTransitionName;
 import static org.briarproject.briar.android.util.UiUtils.getBulbTransitionName;
@@ -185,8 +183,6 @@ public class ConversationActivity extends BriarActivity
 	volatile GroupInvitationManager groupInvitationManager;
 
 	private final Map<MessageId, String> textCache = new ConcurrentHashMap<>();
-	private final Map<MessageId, PrivateMessageHeader> missingAttachments =
-			new ConcurrentHashMap<>();
 	private final Observer<String> contactNameObserver = name -> {
 		requireNonNull(name);
 		loadMessages();
@@ -540,6 +536,7 @@ public class ConversationActivity extends BriarActivity
 		});
 	}
 
+	@DatabaseExecutor
 	private void eagerlyLoadMessageSize(PrivateMessageHeader h) {
 		try {
 			MessageId id = h.getId();
@@ -556,21 +553,11 @@ public class ConversationActivity extends BriarActivity
 			// images we use a grid so the size is fixed
 			List<AttachmentHeader> headers = h.getAttachmentHeaders();
 			if (headers.size() == 1) {
-				List<AttachmentItem> items = attachmentRetriever.cacheGet(id);
-				if (items == null) {
-					LOG.info("Eagerly loading image size for latest message");
-					AttachmentHeader header = headers.get(0);
-					try {
-						Attachment a = attachmentRetriever
-								.getMessageAttachment(header);
-						AttachmentItem item =
-								attachmentRetriever.getAttachmentItem(a, true);
-						attachmentRetriever.cachePut(id, singletonList(item));
-					} catch (NoSuchMessageException e) {
-						LOG.info("Attachment not received yet");
-						missingAttachments.put(header.getMessageId(), h);
-					}
-				}
+				LOG.info("Eagerly loading image size for latest message");
+				AttachmentHeader header = headers.get(0);
+				// get the item to retrieve its size
+				attachmentRetriever
+						.cacheAttachmentItemWithSize(h.getId(), header);
 			}
 		} catch (DbException e) {
 			logException(LOG, WARNING, e);
@@ -651,59 +638,18 @@ public class ConversationActivity extends BriarActivity
 				&& adapter.isScrolledToBottom(layoutManager);
 	}
 
-	private void loadMessageAttachments(PrivateMessageHeader h) {
-		// TODO: Use placeholders for missing/invalid attachments
-		runOnDbThread(() -> {
-			try {
-				// TODO move getting the items off to IoExecutor, if size == 1
-				List<AttachmentHeader> headers = h.getAttachmentHeaders();
-				boolean needsSize = headers.size() == 1;
-				List<AttachmentItem> items = new ArrayList<>(headers.size());
-				for (AttachmentHeader header : headers) {
-					try {
-						Attachment a = attachmentRetriever
-								.getMessageAttachment(header);
-						AttachmentItem item = attachmentRetriever
-								.getAttachmentItem(a, needsSize);
-						items.add(item);
-					} catch (NoSuchMessageException e) {
-						LOG.info("Attachment not received yet");
-						missingAttachments.put(header.getMessageId(), h);
-						return;
-					}
-				}
-				// Don't cache items unless all are present and valid
-				attachmentRetriever.cachePut(h.getId(), items);
-				displayMessageAttachments(h.getId(), items);
-			} catch (DbException e) {
-				logException(LOG, WARNING, e);
-			}
-		});
-	}
-
-	private void displayMessageAttachments(MessageId m,
-			List<AttachmentItem> items) {
-		runOnUiThreadUnlessDestroyed(() -> {
-			Pair<Integer, ConversationMessageItem> pair =
-					adapter.getMessageItem(m);
-			if (pair != null) {
-				boolean scroll = shouldScrollWhenUpdatingMessage();
-				pair.getSecond().setAttachments(items);
-				adapter.notifyItemChanged(pair.getFirst());
-				if (scroll) scrollToBottom();
-			}
-		});
+	@UiThread
+	private void updateMessageAttachment(MessageId m, AttachmentItem item) {
+		Pair<Integer, ConversationMessageItem> pair = adapter.getMessageItem(m);
+		if (pair != null && pair.getSecond().updateAttachments(item)) {
+			boolean scroll = shouldScrollWhenUpdatingMessage();
+			adapter.notifyItemChanged(pair.getFirst());
+			if (scroll) scrollToBottom();
+		}
 	}
 
 	@Override
 	public void eventOccurred(Event e) {
-		if (e instanceof AttachmentReceivedEvent) {
-			AttachmentReceivedEvent a = (AttachmentReceivedEvent) e;
-			if (a.getContactId().equals(contactId)) {
-				LOG.info("Attachment received");
-				onAttachmentReceived(a.getMessageId());
-			}
-		}
 		if (e instanceof ContactRemovedEvent) {
 			ContactRemovedEvent c = (ContactRemovedEvent) e;
 			if (c.getContactId().equals(contactId)) {
@@ -763,15 +709,6 @@ public class ConversationActivity extends BriarActivity
 			scrollToBottom();
 	}
 
-	@UiThread
-	private void onAttachmentReceived(MessageId attachmentId) {
-		PrivateMessageHeader h = missingAttachments.remove(attachmentId);
-		if (h != null) {
-			LOG.info("Missing attachment received");
-			loadMessageAttachments(h);
-		}
-	}
-
 	@UiThread
 	private void onNewConversationMessage(ConversationMessageHeader h) {
 		if (h instanceof ConversationRequest ||
@@ -780,7 +717,7 @@ public class ConversationActivity extends BriarActivity
 			observeOnce(viewModel.getContactDisplayName(), this,
 					name -> addConversationItem(h.accept(visitor)));
 		} else {
-			// visitor also loads message text (if existing)
+			// visitor also loads message text and attachments (if existing)
 			addConversationItem(h.accept(visitor));
 		}
 	}
@@ -1107,8 +1044,9 @@ public class ConversationActivity extends BriarActivity
 		i.putExtra(ATTACHMENT_POSITION, attachments.indexOf(item));
 		i.putExtra(NAME, name);
 		i.putExtra(DATE, messageItem.getTime());
+		i.putExtra(ITEM_ID, messageItem.getId().getBytes());
 		// restoring list position should not trigger android bug #224270
-		String transitionName = item.getTransitionName();
+		String transitionName = item.getTransitionName(messageItem.getId());
 		ActivityOptionsCompat options =
 				makeSceneTransitionAnimation(this, view, transitionName);
 		ActivityCompat.startActivity(this, i, options.toBundle());
@@ -1147,15 +1085,41 @@ public class ConversationActivity extends BriarActivity
 		return text;
 	}
 
+	/**
+	 * Called by {@link PrivateMessageHeader#accept(ConversationMessageVisitor)}
+	 */
 	@Override
 	public List<AttachmentItem> getAttachmentItems(PrivateMessageHeader h) {
-		List<AttachmentItem> attachments =
-				attachmentRetriever.cacheGet(h.getId());
-		if (attachments == null) {
-			loadMessageAttachments(h);
-			return emptyList();
+		List<LiveData<AttachmentItem>> liveDataList =
+				attachmentRetriever.getAttachmentItems(h);
+		List<AttachmentItem> items = new ArrayList<>(liveDataList.size());
+		for (LiveData<AttachmentItem> liveData : liveDataList) {
+			// first remove all our observers to avoid having more than one
+			// in case we reload the conversation, e.g. after deleting messages
+			liveData.removeObservers(this);
+			// add a new observer
+			liveData.observe(this, new AttachmentObserver(h.getId(), liveData));
+			items.add(requireNonNull(liveData.getValue()));
+		}
+		return items;
+	}
+
+	private class AttachmentObserver implements Observer<AttachmentItem> {
+		private final MessageId conversationMessageId;
+		private final LiveData<AttachmentItem> liveData;
+
+		private AttachmentObserver(MessageId conversationMessageId,
+				LiveData<AttachmentItem> liveData) {
+			this.conversationMessageId = conversationMessageId;
+			this.liveData = liveData;
+		}
+
+		@Override
+		public void onChanged(AttachmentItem attachmentItem) {
+			updateMessageAttachment(conversationMessageId, attachmentItem);
+			if (attachmentItem.getState().isFinal())
+				liveData.removeObserver(this);
 		}
-		return attachments;
 	}
 
 }

briar-android/src/main/java/org/briarproject/briar/android/conversation/ConversationMessageItem.java

@@ -9,12 +9,13 @@ import java.util.List;
 import javax.annotation.concurrent.NotThreadSafe;
 
 import androidx.annotation.LayoutRes;
+import androidx.annotation.UiThread;
 
 @NotThreadSafe
 @NotNullByDefault
 class ConversationMessageItem extends ConversationItem {
 
-	private List<AttachmentItem> attachments;
+	private final List<AttachmentItem> attachments;
 
 	ConversationMessageItem(@LayoutRes int layoutRes, PrivateMessageHeader h,
 			List<AttachmentItem> attachments) {
@@ -26,8 +27,14 @@ class ConversationMessageItem extends ConversationItem {
 		return attachments;
 	}
 
-	void setAttachments(List<AttachmentItem> attachments) {
-		this.attachments = attachments;
+	@UiThread
+	boolean updateAttachments(AttachmentItem item) {
+		int pos = attachments.indexOf(item);
+		if (pos != -1 && attachments.get(pos).getState() != item.getState()) {
+			attachments.set(pos, item);
+			return true;
+		}
+		return false;
 	}
 
 }

briar-android/src/main/java/org/briarproject/briar/android/conversation/ConversationViewModel.java

@@ -11,6 +11,9 @@ import org.briarproject.bramble.api.db.DatabaseExecutor;
 import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.db.NoSuchContactException;
 import org.briarproject.bramble.api.db.TransactionManager;
+import org.briarproject.bramble.api.event.Event;
+import org.briarproject.bramble.api.event.EventBus;
+import org.briarproject.bramble.api.event.EventListener;
 import org.briarproject.bramble.api.identity.AuthorId;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.settings.Settings;
@@ -30,6 +33,7 @@ import org.briarproject.briar.api.messaging.MessagingManager;
 import org.briarproject.briar.api.messaging.PrivateMessage;
 import org.briarproject.briar.api.messaging.PrivateMessageFactory;
 import org.briarproject.briar.api.messaging.PrivateMessageHeader;
+import org.briarproject.briar.api.messaging.event.AttachmentReceivedEvent;
 
 import java.util.Collection;
 import java.util.List;
@@ -56,7 +60,7 @@ import static org.briarproject.briar.android.util.UiUtils.observeForeverOnce;
 
 @NotNullByDefault
 public class ConversationViewModel extends AndroidViewModel
-		implements AttachmentManager {
+		implements EventListener, AttachmentManager {
 
 	private static Logger LOG =
 			getLogger(ConversationViewModel.class.getName());
@@ -69,6 +73,7 @@ public class ConversationViewModel extends AndroidViewModel
 	@DatabaseExecutor
 	private final Executor dbExecutor;
 	private final TransactionManager db;
+	private final EventBus eventBus;
 	private final MessagingManager messagingManager;
 	private final ContactManager contactManager;
 	private final SettingsManager settingsManager;
@@ -101,6 +106,7 @@ public class ConversationViewModel extends AndroidViewModel
 	ConversationViewModel(Application application,
 			@DatabaseExecutor Executor dbExecutor,
 			TransactionManager db,
+			EventBus eventBus,
 			MessagingManager messagingManager,
 			ContactManager contactManager,
 			SettingsManager settingsManager,
@@ -110,6 +116,7 @@ public class ConversationViewModel extends AndroidViewModel
 		super(application);
 		this.dbExecutor = dbExecutor;
 		this.db = db;
+		this.eventBus = eventBus;
 		this.messagingManager = messagingManager;
 		this.contactManager = contactManager;
 		this.settingsManager = settingsManager;
@@ -119,12 +126,27 @@ public class ConversationViewModel extends AndroidViewModel
 		messagingGroupId = Transformations
 				.map(contact, c -> messagingManager.getContactGroup(c).getId());
 		contactDeleted.setValue(false);
+
+		eventBus.addListener(this);
 	}
 
 	@Override
 	protected void onCleared() {
 		super.onCleared();
-		attachmentCreator.deleteUnsentAttachments();
+		attachmentCreator.cancel();  // also deletes unsent attachments
+		eventBus.removeListener(this);
+	}
+
+	@Override
+	public void eventOccurred(Event e) {
+		if (e instanceof AttachmentReceivedEvent) {
+			AttachmentReceivedEvent a = (AttachmentReceivedEvent) e;
+			if (a.getContactId().equals(contactId)) {
+				LOG.info("Attachment received");
+				dbExecutor.execute(() -> attachmentRetriever
+						.loadAttachmentItem(a.getMessageId()));
+			}
+		}
 	}
 
 	/**
@@ -252,6 +274,7 @@ public class ConversationViewModel extends AndroidViewModel
 		settingsManager.mergeSettings(settings, SETTINGS_NAMESPACE);
 	}
 
+	@UiThread
 	private void createMessage(GroupId groupId, @Nullable String text,
 			List<AttachmentHeader> headers, long timestamp,
 			boolean hasImageSupport) {
@@ -270,6 +293,7 @@ public class ConversationViewModel extends AndroidViewModel
 		}
 	}
 
+	@UiThread
 	private void storeMessage(PrivateMessage m) {
 		attachmentCreator.onAttachmentsSent(m.getMessage().getId());
 		dbExecutor.execute(() -> {

briar-android/src/main/java/org/briarproject/briar/android/conversation/ImageActivity.java

@@ -16,6 +16,7 @@ import com.google.android.material.appbar.AppBarLayout;
 
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
+import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.activity.ActivityComponent;
 import org.briarproject.briar.android.activity.BriarActivity;
@@ -67,6 +68,7 @@ public class ImageActivity extends BriarActivity
 	final static String ATTACHMENT_POSITION = "position";
 	final static String NAME = "name";
 	final static String DATE = "date";
+	final static String ITEM_ID = "itemId";
 
 	@RequiresApi(api = 16)
 	private final static int UI_FLAGS_DEFAULT =
@@ -80,6 +82,7 @@ public class ImageActivity extends BriarActivity
 	private AppBarLayout appBarLayout;
 	private ViewPager viewPager;
 	private List<AttachmentItem> attachments;
+	private MessageId conversationMessageId;
 
 	@Override
 	public void injectActivity(ActivityComponent component) {
@@ -98,9 +101,20 @@ public class ImageActivity extends BriarActivity
 			setSceneTransitionAnimation(transition, null, transition);
 		}
 
+		// Intent Extras
+		Intent i = getIntent();
+		attachments =
+				requireNonNull(i.getParcelableArrayListExtra(ATTACHMENTS));
+		int position = i.getIntExtra(ATTACHMENT_POSITION, -1);
+		if (position == -1) throw new IllegalStateException();
+		String name = i.getStringExtra(NAME);
+		long time = i.getLongExtra(DATE, 0);
+		byte[] messageIdBytes = requireNonNull(i.getByteArrayExtra(ITEM_ID));
+
 		// get View Model
 		viewModel = ViewModelProviders.of(this, viewModelFactory)
 				.get(ImageViewModel.class);
+		viewModel.expectAttachments(attachments);
 		viewModel.getSaveState().observeEvent(this,
 				this::onImageSaveStateChanged);
 
@@ -124,16 +138,11 @@ public class ImageActivity extends BriarActivity
 		TextView contactName = toolbar.findViewById(R.id.contactName);
 		TextView dateView = toolbar.findViewById(R.id.dateView);
 
-		// Intent Extras
-		Intent i = getIntent();
-		attachments = i.getParcelableArrayListExtra(ATTACHMENTS);
-		int position = i.getIntExtra(ATTACHMENT_POSITION, -1);
-		if (position == -1) throw new IllegalStateException();
-		String name = i.getStringExtra(NAME);
-		long time = i.getLongExtra(DATE, 0);
+		// Set contact name and message time
 		String date = formatDateAbsolute(this, time);
 		contactName.setText(name);
 		dateView.setText(date);
+		conversationMessageId = new MessageId(messageIdBytes);
 
 		// Set up image ViewPager
 		viewPager = findViewById(R.id.viewPager);
@@ -320,8 +329,8 @@ public class ImageActivity extends BriarActivity
 
 		@Override
 		public Fragment getItem(int position) {
-			Fragment f = ImageFragment
-					.newInstance(attachments.get(position), isFirst);
+			Fragment f = ImageFragment.newInstance(
+					attachments.get(position), conversationMessageId, isFirst);
 			isFirst = false;
 			return f;
 		}

briar-android/src/main/java/org/briarproject/briar/android/conversation/ImageAdapter.java

@@ -49,7 +49,8 @@ class ImageAdapter extends Adapter<ImageViewHolder> {
 	public ImageViewHolder onCreateViewHolder(ViewGroup viewGroup, int type) {
 		View v = LayoutInflater.from(viewGroup.getContext()).inflate(
 				R.layout.list_item_image, viewGroup, false);
-		return new ImageViewHolder(v, imageSize);
+		requireNonNull(conversationItem);
+		return new ImageViewHolder(v, imageSize, conversationItem.getId());
 	}
 
 	@Override

briar-android/src/main/java/org/briarproject/briar/android/conversation/ImageFragment.java

@@ -15,6 +15,7 @@ import com.bumptech.glide.request.target.Target;
 import com.github.chrisbanes.photoview.PhotoView;
 
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
+import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.activity.BaseActivity;
 import org.briarproject.briar.android.attachment.AttachmentItem;
@@ -23,6 +24,7 @@ import org.briarproject.briar.android.conversation.glide.GlideApp;
 import javax.annotation.ParametersAreNonnullByDefault;
 import javax.inject.Inject;
 
+import androidx.annotation.DrawableRes;
 import androidx.annotation.Nullable;
 import androidx.fragment.app.Fragment;
 import androidx.lifecycle.ViewModelProvider;
@@ -32,27 +34,36 @@ import static android.os.Build.VERSION.SDK_INT;
 import static android.widget.ImageView.ScaleType.FIT_START;
 import static com.bumptech.glide.load.engine.DiskCacheStrategy.NONE;
 import static org.briarproject.bramble.api.nullsafety.NullSafety.requireNonNull;
+import static org.briarproject.briar.android.attachment.AttachmentItem.State.AVAILABLE;
+import static org.briarproject.briar.android.attachment.AttachmentItem.State.ERROR;
 import static org.briarproject.briar.android.conversation.ImageActivity.ATTACHMENT_POSITION;
+import static org.briarproject.briar.android.conversation.ImageActivity.ITEM_ID;
 
 @MethodsNotNullByDefault
 @ParametersAreNonnullByDefault
-public class ImageFragment extends Fragment {
+public class ImageFragment extends Fragment
+		implements RequestListener<Drawable> {
 
 	private final static String IS_FIRST = "isFirst";
+	@DrawableRes
+	private static final int ERROR_RES = R.drawable.ic_image_broken;
 
 	@Inject
 	ViewModelProvider.Factory viewModelFactory;
 
 	private AttachmentItem attachment;
 	private boolean isFirst;
+	private MessageId conversationItemId;
 	private ImageViewModel viewModel;
 	private PhotoView photoView;
 
-	static ImageFragment newInstance(AttachmentItem a, boolean isFirst) {
+	static ImageFragment newInstance(AttachmentItem a,
+			MessageId conversationMessageId, boolean isFirst) {
 		ImageFragment f = new ImageFragment();
 		Bundle args = new Bundle();
 		args.putParcelable(ATTACHMENT_POSITION, a);
 		args.putBoolean(IS_FIRST, isFirst);
+		args.putByteArray(ITEM_ID, conversationMessageId.getBytes());
 		f.setArguments(args);
 		return f;
 	}
@@ -70,6 +81,8 @@ public class ImageFragment extends Fragment {
 		Bundle args = requireNonNull(getArguments());
 		attachment = requireNonNull(args.getParcelable(ATTACHMENT_POSITION));
 		isFirst = args.getBoolean(IS_FIRST);
+		conversationItemId =
+				new MessageId(requireNonNull(args.getByteArray(ITEM_ID)));
 	}
 
 	@Nullable
@@ -87,50 +100,68 @@ public class ImageFragment extends Fragment {
 		photoView.setScaleLevels(1, 2, 4);
 		photoView.setOnClickListener(view -> viewModel.clickImage());
 
-		// Request Listener
-		RequestListener<Drawable> listener = new RequestListener<Drawable>() {
-
-			@Override
-			public boolean onLoadFailed(@Nullable GlideException e,
-					Object model, Target<Drawable> target,
-					boolean isFirstResource) {
-				if (getActivity() != null && isFirst)
-					getActivity().supportStartPostponedEnterTransition();
-				return false;
-			}
-
-			@Override
-			public boolean onResourceReady(Drawable resource, Object model,
-					Target<Drawable> target, DataSource dataSource,
-					boolean isFirstResource) {
-				if (SDK_INT >= 21 && !(resource instanceof Animatable)) {
-					// set transition name only when not animatable,
-					// because the animation won't start otherwise
-					photoView.setTransitionName(
-							attachment.getTransitionName());
-				}
-				// Move image to the top if overlapping toolbar
-				if (viewModel.isOverlappingToolbar(photoView, resource)) {
-					photoView.setScaleType(FIT_START);
-				}
-				if (getActivity() != null && isFirst) {
-					getActivity().supportStartPostponedEnterTransition();
-				}
-				return false;
-			}
-		};
-
-		// Load Image
-		GlideApp.with(this)
-				.load(attachment)
-				// TODO allow if size < maxTextureSize ?
-//				.override(SIZE_ORIGINAL)
-				.diskCacheStrategy(NONE)
-				.error(R.drawable.ic_image_broken)
-				.addListener(listener)
-				.into(photoView);
+		if (attachment.getState() == AVAILABLE) {
+			loadImage();
+			// postponed transition will be started when Image was loaded
+		} else if (attachment.getState() == ERROR) {
+			photoView.setImageResource(ERROR_RES);
+			startPostponedTransition();
+		} else {
+			photoView.setImageResource(R.drawable.ic_image_missing);
+			startPostponedTransition();
+			// state is not final, so observe state changes
+			viewModel.getOnAttachmentReceived(attachment.getMessageId())
+					.observeEvent(this, this::onAttachmentReceived);
+		}
 
 		return v;
 	}
 
+	private void loadImage() {
+		GlideApp.with(this)
+				.load(attachment)
+				// TODO allow if size < maxTextureSize ?
+//					.override(SIZE_ORIGINAL)
+				.diskCacheStrategy(NONE)
+				.error(ERROR_RES)
+				.addListener(this)
+				.into(photoView);
+	}
+
+	private void onAttachmentReceived(Boolean received) {
+		if (received) loadImage();
+	}
+
+	@Override
+	public boolean onLoadFailed(@Nullable GlideException e,
+			Object model, Target<Drawable> target,
+			boolean isFirstResource) {
+		startPostponedTransition();
+		return false;
+	}
+
+	@Override
+	public boolean onResourceReady(Drawable resource, Object model,
+			Target<Drawable> target, DataSource dataSource,
+			boolean isFirstResource) {
+		if (SDK_INT >= 21 && !(resource instanceof Animatable)) {
+			// set transition name only when not animatable,
+			// because the animation won't start otherwise
+			photoView.setTransitionName(
+					attachment.getTransitionName(conversationItemId));
+		}
+		// Move image to the top if overlapping toolbar
+		if (viewModel.isOverlappingToolbar(photoView, resource)) {
+			photoView.setScaleType(FIT_START);
+		}
+		startPostponedTransition();
+		return false;
+	}
+
+	private void startPostponedTransition() {
+		if (getActivity() != null && isFirst) {
+			getActivity().supportStartPostponedEnterTransition();
+		}
+	}
+
 }

briar-android/src/main/java/org/briarproject/briar/android/conversation/ImageViewHolder.java

@@ -7,6 +7,7 @@ import android.widget.ImageView;
 import com.bumptech.glide.load.Transformation;
 
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.attachment.AttachmentItem;
 import org.briarproject.briar.android.conversation.glide.BriarImageTransformation;
@@ -18,8 +19,12 @@ import androidx.recyclerview.widget.RecyclerView.ViewHolder;
 import androidx.recyclerview.widget.StaggeredGridLayoutManager.LayoutParams;
 
 import static android.os.Build.VERSION.SDK_INT;
+import static android.widget.ImageView.ScaleType.CENTER_CROP;
+import static android.widget.ImageView.ScaleType.FIT_CENTER;
 import static com.bumptech.glide.load.engine.DiskCacheStrategy.NONE;
 import static com.bumptech.glide.load.resource.drawable.DrawableTransitionOptions.withCrossFade;
+import static org.briarproject.briar.android.attachment.AttachmentItem.State.AVAILABLE;
+import static org.briarproject.briar.android.attachment.AttachmentItem.State.ERROR;
 
 @NotNullByDefault
 class ImageViewHolder extends ViewHolder {
@@ -29,25 +34,33 @@ class ImageViewHolder extends ViewHolder {
 
 	protected final ImageView imageView;
 	private final int imageSize;
+	private final MessageId conversationItemId;
 
-	ImageViewHolder(View v, int imageSize) {
+	ImageViewHolder(View v, int imageSize, MessageId conversationItemId) {
 		super(v);
 		imageView = v.findViewById(R.id.imageView);
 		this.imageSize = imageSize;
+		this.conversationItemId = conversationItemId;
 	}
 
 	void bind(AttachmentItem attachment, Radii r, boolean single,
 			boolean needsStretch) {
-		if (attachment.hasError()) {
-			GlideApp.with(imageView)
-					.clear(imageView);
-			imageView.setImageResource(ERROR_RES);
-		} else {
-			setImageViewDimensions(attachment, single, needsStretch);
-			loadImage(attachment, r);
-			if (SDK_INT >= 21) {
-				imageView.setTransitionName(attachment.getTransitionName());
+		setImageViewDimensions(attachment, single, needsStretch);
+		if (attachment.getState() != AVAILABLE) {
+			GlideApp.with(imageView).clear(imageView);
+			if (attachment.getState() == ERROR) {
+				imageView.setImageResource(ERROR_RES);
+			} else {
+				imageView.setImageResource(R.drawable.ic_image_missing);
 			}
+			imageView.setScaleType(FIT_CENTER);
+		} else {
+			loadImage(attachment, r);
+			imageView.setScaleType(CENTER_CROP);
+		}
+		if (SDK_INT >= 21) {
+			imageView.setTransitionName(
+					attachment.getTransitionName(conversationItemId));
 		}
 	}
 

briar-android/src/main/java/org/briarproject/briar/android/conversation/ImageViewModel.java

@@ -7,13 +7,18 @@ import android.view.View;
 
 import org.briarproject.bramble.api.db.DatabaseExecutor;
 import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.event.Event;
+import org.briarproject.bramble.api.event.EventBus;
+import org.briarproject.bramble.api.event.EventListener;
 import org.briarproject.bramble.api.lifecycle.IoExecutor;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.briar.android.attachment.AttachmentItem;
 import org.briarproject.briar.android.viewmodel.LiveEvent;
 import org.briarproject.briar.android.viewmodel.MutableLiveEvent;
 import org.briarproject.briar.api.messaging.Attachment;
 import org.briarproject.briar.api.messaging.MessagingManager;
+import org.briarproject.briar.api.messaging.event.AttachmentReceivedEvent;
 
 import java.io.File;
 import java.io.FileOutputStream;
@@ -22,6 +27,8 @@ import java.io.InputStream;
 import java.io.OutputStream;
 import java.text.SimpleDateFormat;
 import java.util.Date;
+import java.util.HashMap;
+import java.util.List;
 import java.util.Locale;
 import java.util.concurrent.Executor;
 import java.util.logging.Logger;
@@ -35,22 +42,28 @@ import androidx.lifecycle.AndroidViewModel;
 import static android.media.MediaScannerConnection.scanFile;
 import static android.os.Environment.DIRECTORY_PICTURES;
 import static android.os.Environment.getExternalStoragePublicDirectory;
+import static java.util.Objects.requireNonNull;
 import static java.util.logging.Level.WARNING;
 import static java.util.logging.Logger.getLogger;
 import static org.briarproject.bramble.util.IoUtils.copyAndClose;
 import static org.briarproject.bramble.util.LogUtils.logException;
 
 @NotNullByDefault
-public class ImageViewModel extends AndroidViewModel {
+public class ImageViewModel extends AndroidViewModel implements EventListener {
 
 	private static Logger LOG = getLogger(ImageViewModel.class.getName());
 
 	private final MessagingManager messagingManager;
+	private final EventBus eventBus;
 	@DatabaseExecutor
 	private final Executor dbExecutor;
 	@IoExecutor
 	private final Executor ioExecutor;
 
+	private boolean receivedAttachmentsInitialized = false;
+	private HashMap<MessageId, MutableLiveEvent<Boolean>> receivedAttachments =
+			new HashMap<>();
+
 	/**
 	 * true means there was an error saving the image, false if image was saved.
 	 */
@@ -62,13 +75,60 @@ public class ImageViewModel extends AndroidViewModel {
 
 	@Inject
 	ImageViewModel(Application application,
-			MessagingManager messagingManager,
+			MessagingManager messagingManager, EventBus eventBus,
 			@DatabaseExecutor Executor dbExecutor,
 			@IoExecutor Executor ioExecutor) {
 		super(application);
 		this.messagingManager = messagingManager;
+		this.eventBus = eventBus;
 		this.dbExecutor = dbExecutor;
 		this.ioExecutor = ioExecutor;
+
+		eventBus.addListener(this);
+	}
+
+	@Override
+	protected void onCleared() {
+		super.onCleared();
+		eventBus.removeListener(this);
+	}
+
+	@UiThread
+	@Override
+	public void eventOccurred(Event e) {
+		if (e instanceof AttachmentReceivedEvent) {
+			MessageId id = ((AttachmentReceivedEvent) e).getMessageId();
+			MutableLiveEvent<Boolean> oldEvent;
+			if (receivedAttachmentsInitialized) {
+				oldEvent = receivedAttachments.get(id);
+				if (oldEvent != null) oldEvent.postEvent(true);
+			} else {
+				receivedAttachments.put(id, new MutableLiveEvent<>(true));
+			}
+		}
+	}
+
+	@UiThread
+	public void expectAttachments(List<AttachmentItem> attachments) {
+		for (AttachmentItem item : attachments) {
+			// no need to track items that are in a final state already
+			if (item.getState().isFinal()) continue;
+			// add new live events, if not already added by eventOccurred()
+			MessageId id = item.getMessageId();
+			if (!receivedAttachments.containsKey(id)) {
+				receivedAttachments.put(id, new MutableLiveEvent<>());
+			}
+		}
+		receivedAttachmentsInitialized = true;
+	}
+
+	/**
+	 * Returns a LiveData for attachments in a non-final state.
+	 * Note that you need to call {@link #expectAttachments(List)} first.
+	 */
+	@UiThread
+	LiveEvent<Boolean> getOnAttachmentReceived(MessageId messageId) {
+		return requireNonNull(receivedAttachments.get(messageId));
 	}
 
 	void clickImage() {

briar-android/src/main/java/org/briarproject/briar/android/keyagreement/ContactExchangeActivity.java

@@ -9,7 +9,6 @@ import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.activity.ActivityComponent;
-import org.briarproject.briar.android.fragment.BaseFragment;
 
 import javax.annotation.Nullable;
 import javax.inject.Inject;
@@ -114,9 +113,7 @@ public class ContactExchangeActivity extends KeyAgreementActivity {
 		return getString(R.string.exchanging_contact_details);
 	}
 
-	protected void showErrorFragment() {
-		String errorMsg = getString(R.string.connection_error_explanation);
-		BaseFragment f = ContactExchangeErrorFragment.newInstance(errorMsg);
-		showNextFragment(f);
+	private void showErrorFragment() {
+		showNextFragment(new ContactExchangeErrorFragment());
 	}
 }

briar-android/src/main/java/org/briarproject/briar/android/keyagreement/ContactExchangeErrorFragment.java

@@ -1,5 +1,6 @@
 package org.briarproject.briar.android.keyagreement;
 
+import android.content.Intent;
 import android.os.Bundle;
 import android.view.LayoutInflater;
 import android.view.View;
@@ -18,7 +19,10 @@ import org.briarproject.briar.android.util.UiUtils;
 import javax.inject.Inject;
 
 import androidx.annotation.Nullable;
+import androidx.fragment.app.FragmentActivity;
 
+import static android.content.Intent.FLAG_ACTIVITY_CLEAR_TOP;
+import static android.view.View.GONE;
 import static org.briarproject.briar.android.util.UiUtils.onSingleLinkClick;
 
 @MethodsNotNullByDefault
@@ -58,13 +62,12 @@ public class ContactExchangeErrorFragment extends BaseFragment {
 		View v = inflater.inflate(R.layout.fragment_error_contact_exchange,
 				container, false);
 
-		// set humanized error message
+		// set optional error message
 		TextView explanation = v.findViewById(R.id.errorMessage);
 		Bundle args = getArguments();
-		if (args == null) {
-			throw new IllegalArgumentException("Use newInstance()");
-		}
-		explanation.setText(args.getString(ERROR_MSG));
+		String errorMessage = args == null ? null : args.getString(ERROR_MSG);
+		if (errorMessage == null) explanation.setVisibility(GONE);
+		else explanation.setText(args.getString(ERROR_MSG));
 
 		// make feedback link clickable
 		TextView sendFeedback = v.findViewById(R.id.sendFeedback);
@@ -73,7 +76,11 @@ public class ContactExchangeErrorFragment extends BaseFragment {
 		// buttons
 		Button tryAgain = v.findViewById(R.id.tryAgainButton);
 		tryAgain.setOnClickListener(view -> {
-			if (getActivity() != null) getActivity().onBackPressed();
+			// Recreate the activity so we return to the intro fragment
+			FragmentActivity activity = requireActivity();
+			Intent i = new Intent(activity, ContactExchangeActivity.class);
+			i.setFlags(FLAG_ACTIVITY_CLEAR_TOP);
+			activity.startActivity(i);
 		});
 		Button cancel = v.findViewById(R.id.cancelButton);
 		cancel.setOnClickListener(view -> finish());

briar-android/src/main/java/org/briarproject/briar/android/keyagreement/KeyAgreementActivity.java

@@ -26,7 +26,6 @@ import org.briarproject.briar.android.fragment.BaseFragment;
 import org.briarproject.briar.android.fragment.BaseFragment.BaseFragmentListener;
 import org.briarproject.briar.android.keyagreement.IntroFragment.IntroScreenSeenListener;
 import org.briarproject.briar.android.keyagreement.KeyAgreementFragment.KeyAgreementEventListener;
-import org.briarproject.briar.android.util.UiUtils;
 
 import java.util.logging.Logger;
 
@@ -46,6 +45,7 @@ import static android.bluetooth.BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE;
 import static android.bluetooth.BluetoothAdapter.ACTION_SCAN_MODE_CHANGED;
 import static android.bluetooth.BluetoothAdapter.SCAN_MODE_CONNECTABLE_DISCOVERABLE;
 import static android.content.pm.PackageManager.PERMISSION_GRANTED;
+import static android.os.Build.VERSION.SDK_INT;
 import static java.util.logging.Level.INFO;
 import static java.util.logging.Logger.getLogger;
 import static org.briarproject.bramble.api.nullsafety.NullSafety.requireNonNull;
@@ -55,6 +55,7 @@ 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.briar.android.activity.RequestCodes.REQUEST_BLUETOOTH_DISCOVERABLE;
 import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_PERMISSION_CAMERA_LOCATION;
+import static org.briarproject.briar.android.util.UiUtils.getGoToSettingsListener;
 
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
@@ -133,6 +134,8 @@ public abstract class KeyAgreementActivity extends BriarActivity implements
 	private Permission locationPermission = Permission.UNKNOWN;
 	private BluetoothDecision bluetoothDecision = BluetoothDecision.UNKNOWN;
 	private BroadcastReceiver bluetoothReceiver = null;
+	private Plugin wifiPlugin = null, bluetoothPlugin = null;
+	private BluetoothAdapter bt = null;
 
 	@Override
 	public void injectActivity(ActivityComponent component) {
@@ -152,6 +155,9 @@ public abstract class KeyAgreementActivity extends BriarActivity implements
 		IntentFilter filter = new IntentFilter(ACTION_SCAN_MODE_CHANGED);
 		bluetoothReceiver = new BluetoothStateReceiver();
 		registerReceiver(bluetoothReceiver, filter);
+		wifiPlugin = pluginManager.getPlugin(LanTcpConstants.ID);
+		bluetoothPlugin = pluginManager.getPlugin(BluetoothConstants.ID);
+		bt = BluetoothAdapter.getDefaultAdapter();
 	}
 
 	@Override
@@ -187,6 +193,7 @@ public abstract class KeyAgreementActivity extends BriarActivity implements
 		showQrCodeFragmentIfAllowed();
 	}
 
+	@SuppressWarnings("StatementWithEmptyBody")
 	private void showQrCodeFragmentIfAllowed() {
 		if (isResumed && continueClicked && areEssentialPermissionsGranted()) {
 			if (isWifiReady() && isBluetoothReady()) {
@@ -200,6 +207,8 @@ public abstract class KeyAgreementActivity extends BriarActivity implements
 				}
 				if (bluetoothDecision == BluetoothDecision.UNKNOWN) {
 					requestBluetoothDiscoverable();
+				} else if (bluetoothDecision == BluetoothDecision.REFUSED) {
+					// Ask again when the user clicks "continue"
 				} else if (shouldEnableBluetooth()) {
 					LOG.info("Enabling Bluetooth plugin");
 					hasEnabledBluetooth = true;
@@ -210,55 +219,50 @@ public abstract class KeyAgreementActivity extends BriarActivity implements
 	}
 
 	private boolean areEssentialPermissionsGranted() {
-		// If the camera permission has been granted, and the location
-		// permission has been granted or permanently denied, we can continue
 		return cameraPermission == Permission.GRANTED &&
-				(locationPermission == Permission.GRANTED ||
-						locationPermission == Permission.PERMANENTLY_DENIED);
+				(SDK_INT < 23 || locationPermission == Permission.GRANTED ||
+						!isBluetoothSupported());
+	}
+
+	private boolean isBluetoothSupported() {
+		return bt != null && bluetoothPlugin != null;
 	}
 
 	private boolean isWifiReady() {
-		Plugin p = pluginManager.getPlugin(LanTcpConstants.ID);
-		if (p == null) return true; // Continue without wifi
-		State state = p.getState();
+		if (wifiPlugin == null) return true; // Continue without wifi
+		State state = wifiPlugin.getState();
 		// Wait for plugin to become enabled
 		return state == ACTIVE || state == INACTIVE;
 	}
 
 	private boolean isBluetoothReady() {
-		if (bluetoothDecision == BluetoothDecision.UNKNOWN ||
-				bluetoothDecision == BluetoothDecision.WAITING) {
-			// Wait for decision
-			return false;
-		}
-		if (bluetoothDecision == BluetoothDecision.NO_ADAPTER
-				|| bluetoothDecision == BluetoothDecision.REFUSED) {
+		if (!isBluetoothSupported()) {
 			// Continue without Bluetooth
 			return true;
 		}
-		BluetoothAdapter bt = BluetoothAdapter.getDefaultAdapter();
-		if (bt == null) return true; // Continue without Bluetooth
+		if (bluetoothDecision == BluetoothDecision.UNKNOWN ||
+				bluetoothDecision == BluetoothDecision.WAITING ||
+				bluetoothDecision == BluetoothDecision.REFUSED) {
+			// Wait for user to accept
+			return false;
+		}
 		if (bt.getScanMode() != SCAN_MODE_CONNECTABLE_DISCOVERABLE) {
 			// Wait for adapter to become discoverable
 			return false;
 		}
-		Plugin p = pluginManager.getPlugin(BluetoothConstants.ID);
-		if (p == null) return true; // Continue without Bluetooth
 		// Wait for plugin to become active
-		return p.getState() == ACTIVE;
+		return bluetoothPlugin.getState() == ACTIVE;
 	}
 
 	private boolean shouldEnableWifi() {
 		if (hasEnabledWifi) return false;
-		Plugin p = pluginManager.getPlugin(LanTcpConstants.ID);
-		if (p == null) return false;
-		State state = p.getState();
+		if (wifiPlugin == null) return false;
+		State state = wifiPlugin.getState();
 		return state == STARTING_STOPPING || state == DISABLED;
 	}
 
 	private void requestBluetoothDiscoverable() {
-		BluetoothAdapter bt = BluetoothAdapter.getDefaultAdapter();
-		if (bt == null) {
+		if (!isBluetoothSupported()) {
 			bluetoothDecision = BluetoothDecision.NO_ADAPTER;
 			showQrCodeFragmentIfAllowed();
 		} else {
@@ -277,9 +281,8 @@ public abstract class KeyAgreementActivity extends BriarActivity implements
 	private boolean shouldEnableBluetooth() {
 		if (bluetoothDecision != BluetoothDecision.ACCEPTED) return false;
 		if (hasEnabledBluetooth) return false;
-		Plugin p = pluginManager.getPlugin(BluetoothConstants.ID);
-		if (p == null) return false;
-		State state = p.getState();
+		if (!isBluetoothSupported()) return false;
+		State state = bluetoothPlugin.getState();
 		return state == STARTING_STOPPING || state == DISABLED;
 	}
 
@@ -298,6 +301,9 @@ public abstract class KeyAgreementActivity extends BriarActivity implements
 	@Override
 	public void showNextScreen() {
 		continueClicked = true;
+		if (bluetoothDecision == BluetoothDecision.REFUSED) {
+			bluetoothDecision = BluetoothDecision.UNKNOWN; // Ask again
+		}
 		if (checkPermissions()) showQrCodeFragmentIfAllowed();
 	}
 
@@ -341,17 +347,17 @@ public abstract class KeyAgreementActivity extends BriarActivity implements
 
 	private boolean checkPermissions() {
 		if (areEssentialPermissionsGranted()) return true;
-		// If the camera permission has been permanently denied, ask the
+		// If an essential permission has been permanently denied, ask the
 		// user to change the setting
 		if (cameraPermission == Permission.PERMANENTLY_DENIED) {
-			Builder builder = new Builder(this, R.style.BriarDialogTheme);
-			builder.setTitle(R.string.permission_camera_title);
-			builder.setMessage(R.string.permission_camera_denied_body);
-			builder.setPositiveButton(R.string.ok,
-					UiUtils.getGoToSettingsListener(this));
-			builder.setNegativeButton(R.string.cancel,
-					(dialog, which) -> supportFinishAfterTransition());
-			builder.show();
+			showDenialDialog(R.string.permission_camera_title,
+					R.string.permission_camera_denied_body);
+			return false;
+		}
+		if (isBluetoothSupported() &&
+				locationPermission == Permission.PERMANENTLY_DENIED) {
+			showDenialDialog(R.string.permission_location_title,
+					R.string.permission_location_denied_body);
 			return false;
 		}
 		// Should we show the rationale for one or both permissions?
@@ -371,6 +377,16 @@ public abstract class KeyAgreementActivity extends BriarActivity implements
 		return false;
 	}
 
+	private void showDenialDialog(@StringRes int title, @StringRes int body) {
+		Builder builder = new Builder(this, R.style.BriarDialogTheme);
+		builder.setTitle(title);
+		builder.setMessage(body);
+		builder.setPositiveButton(R.string.ok, getGoToSettingsListener(this));
+		builder.setNegativeButton(R.string.cancel,
+				(dialog, which) -> supportFinishAfterTransition());
+		builder.show();
+	}
+
 	private void showRationale(@StringRes int title, @StringRes int body) {
 		Builder builder = new Builder(this, R.style.BriarDialogTheme);
 		builder.setTitle(title);
@@ -381,8 +397,13 @@ public abstract class KeyAgreementActivity extends BriarActivity implements
 	}
 
 	private void requestPermissions() {
-		ActivityCompat.requestPermissions(this,
-				new String[] {CAMERA, ACCESS_FINE_LOCATION},
+		String[] permissions;
+		if (isBluetoothSupported()) {
+			permissions = new String[] {CAMERA, ACCESS_FINE_LOCATION};
+		} else {
+			permissions = new String[] {CAMERA};
+		}
+		ActivityCompat.requestPermissions(this, permissions,
 				REQUEST_PERMISSION_CAMERA_LOCATION);
 	}
 
@@ -399,12 +420,15 @@ public abstract class KeyAgreementActivity extends BriarActivity implements
 		} else {
 			cameraPermission = Permission.PERMANENTLY_DENIED;
 		}
-		if (gotPermission(ACCESS_FINE_LOCATION, permissions, grantResults)) {
-			locationPermission = Permission.GRANTED;
-		} else if (shouldShowRationale(ACCESS_FINE_LOCATION)) {
-			locationPermission = Permission.SHOW_RATIONALE;
-		} else {
-			locationPermission = Permission.PERMANENTLY_DENIED;
+		if (isBluetoothSupported()) {
+			if (gotPermission(ACCESS_FINE_LOCATION, permissions,
+					grantResults)) {
+				locationPermission = Permission.GRANTED;
+			} else if (shouldShowRationale(ACCESS_FINE_LOCATION)) {
+				locationPermission = Permission.SHOW_RATIONALE;
+			} else {
+				locationPermission = Permission.PERMANENTLY_DENIED;
+			}
 		}
 		// If a permission dialog has been shown, showing the QR code fragment
 		// on this call path would cause a crash due to

briar-android/src/main/java/org/briarproject/briar/android/view/ImagePreview.java

@@ -79,7 +79,7 @@ public class ImagePreview extends ConstraintLayout {
 				((ImagePreviewAdapter) imageList.getAdapter());
 		int pos = requireNonNull(adapter).loadItemPreview(result);
 		if (pos != NO_POSITION) {
-			imageList.smoothScrollToPosition(pos);
+			imageList.scrollToPosition(pos);
 		}
 	}
 

briar-android/src/main/java/org/briarproject/briar/android/viewmodel/LiveEvent.java

@@ -12,6 +12,22 @@ import androidx.lifecycle.Observer;
 @NotNullByDefault
 public class LiveEvent<T> extends LiveData<LiveEvent.ConsumableEvent<T>> {
 
+	/**
+	 * Creates a LiveEvent initialized with the given {@code value}.
+	 *
+	 * @param value initial value
+	 */
+	public LiveEvent(T value) {
+		super(new ConsumableEvent<>(value));
+	}
+
+	/**
+	 * Creates a LiveEvent with no value assigned to it.
+	 */
+	public LiveEvent() {
+		super();
+	}
+
 	public void observeEvent(LifecycleOwner owner,
 			LiveEventHandler<T> handler) {
 		LiveEventObserver<T> observer = new LiveEventObserver<>(handler);

briar-android/src/main/java/org/briarproject/briar/android/viewmodel/MutableLiveEvent.java

@@ -5,6 +5,22 @@ import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 @NotNullByDefault
 public class MutableLiveEvent<T> extends LiveEvent<T> {
 
+	/**
+	 * Creates a MutableLiveEvent initialized with the given {@code value}.
+	 *
+	 * @param value initial value
+	 */
+	public MutableLiveEvent(T value) {
+		super(value);
+	}
+
+	/**
+	 * Creates a MutableLiveEvent with no value assigned to it.
+	 */
+	public MutableLiveEvent() {
+		super();
+	}
+
 	public void postEvent(T value) {
 		super.postValue(new ConsumableEvent<>(value));
 	}

briar-android/src/main/res/drawable/ic_image_broken.xml

@@ -1,6 +1,6 @@
 <vector xmlns:android="http://schemas.android.com/apk/res/android"
-        android:width="200dp"
-        android:height="200dp"
+        android:width="115dp"
+        android:height="115dp"
         android:viewportHeight="24.0"
         android:viewportWidth="24.0">
 	<path

briar-android/src/main/res/drawable/ic_image_missing.xml

@@ -0,0 +1,10 @@
+<vector
+	xmlns:android="http://schemas.android.com/apk/res/android"
+	android:width="115dp"
+	android:height="115dp"
+	android:viewportHeight="24.0"
+	android:viewportWidth="24.0">
+	<path
+		android:fillColor="#808080"
+		android:pathData="M21,19V5c0,-1.1 -0.9,-2 -2,-2H5c-1.1,0 -2,0.9 -2,2v14c0,1.1 0.9,2 2,2h14c1.1,0 2,-0.9 2,-2zM8.5,13.5l2.5,3.01L14.5,12l4.5,6H5l3.5,-4.5z"/>
+</vector>

briar-android/src/main/res/layout/list_item_crash.xml

@@ -24,6 +24,7 @@
 		android:layout_height="wrap_content"
 		android:layout_marginTop="4dp"
 		android:textColor="?android:attr/textColorSecondary"
+		android:textIsSelectable="true"
 		app:layout_constraintEnd_toEndOf="parent"
 		app:layout_constraintStart_toStartOf="parent"
 		app:layout_constraintTop_toBottomOf="@+id/include_in_report"

briar-android/src/main/res/values-ar/strings.xml

@@ -27,6 +27,7 @@
   <string name="enter_password">‮كلمة السّر</string>
   <string name="try_again">كلمة السرّ خاطئة, الرجاء المحاولة مجدّدا</string>
   <string name="dialog_title_cannot_check_password">لا يمكن التحقق من كلمة السر</string>
+  <string name="dialog_message_cannot_check_password">Briar لم يتمكن من التحقق من كلمة المرور. الرجاء إعادة تشغيل جهازك من أجل جل المشكلة</string>
   <string name="sign_in_button">تسجيل الدخول</string>
   <string name="forgotten_password">نسيتُ كلمة السر</string>
   <string name="dialog_title_lost_password">فقدت كلمة السر</string>
@@ -64,12 +65,36 @@
   <string name="lock_button">قفل التطبيق</string>
   <string name="settings_button">الإعدادات</string>
   <string name="sign_out_button">تسجيل الخروج</string>
+  <string name="transports_onboarding_text">إلمس هنا من أجل التحكم بطريقةالربط مع جهات الاتصال.</string>
   <!--Transports: Tor-->
   <string name="transport_tor">إنترنت</string>
+  <string name="tor_device_status_online_wifi">جهازك لديه ولوج لشبكة الانترنت عبر ال Wi-Fi </string>
+  <string name="tor_device_status_online_mobile">جهازك لديه ولوج لشبكة الانترنت عبر بيانات الهاتف</string>
+  <string name="tor_device_status_offline">جهازك ليس متصل بالانترنت</string>
+  <string name="tor_plugin_status_enabling">جاري اتصال Briar  بالانترنت</string>
+  <string name="tor_plugin_status_active">Briar متصل بالانترنت</string>
+  <string name="tor_plugin_status_inactive">Briar لم يتمكن من  الاتصال بالانترنت </string>
+  <string name="tor_plugin_status_disabled">إعدادات Briar لاتسمح بالاتصال بالانترنت</string>
+  <string name="tor_plugin_status_disabled_mobile_data">إعدادات Briar لاتسمح بالاتصال عن طريق بيانات الهاتف</string>
+  <string name="tor_plugin_status_disabled_battery">إعدادات Briar لاتسمح بالاتصال بالانترنت عند استخدام بطارية الهاتف</string>
+  <string name="tor_plugin_status_disabled_country_blocked">لايمكن استخدام Briar في هذا البلد</string>
   <!--Transports: Wi-Fi-->
   <string name="transport_lan">واي-فاي</string>
+  <string name="transport_lan_long">نفس شبكة الWi-Fi </string>
+  <string name="lan_device_status_on">جهازك متصل بشبكة الWi-Fi</string>
+  <string name="lan_device_status_off">جهازك ليس متصل بشبكة الWi-Fi</string>
+  <string name="lan_plugin_status_enabling">جاري ايصال Briar بشبكة الWi-Fi</string>
+  <string name="lan_plugin_status_active"> Briar متصل بشبكة الWi-Fi</string>
+  <string name="lan_plugin_status_inactive">لم يتمكن Briar من الاتصال بشبكة ال Wi-Fi</string>
+  <string name="lan_plugin_status_disabled">إعدادات Briar لاتسمح بالاتصال بشبكة ال Wi-Fi</string>
   <!--Transports: Bluetooth-->
   <string name="transport_bt">بلوتوث</string>
+  <string name="bt_device_status_on"> البلوتوث مفعّل  </string>
+  <string name="bt_device_status_off">البلوتوث مفعّل</string>
+  <string name="bt_plugin_status_enabling">جاري اتصال Briar بالبلوتوث</string>
+  <string name="bt_plugin_status_active">Briar متصل بالبلوتوث</string>
+  <string name="bt_plugin_status_inactive">لم يتمكن Briar من الاتصال بالانترنت</string>
+  <string name="bt_plugin_status_disabled">إعدادات Briar لاتسمح بالاتصال بالبلوتوث</string>
   <!--Notifications-->
   <string name="reminder_notification_title">تم تسجيل الخروج من Briar (براير)</string>
   <string name="reminder_notification_text">الرجاء اللمس لإعادة الدخول</string>
@@ -459,6 +484,8 @@
   <string name="tor_enable_summary">كل جهات الاتصال تمر عبر شبكة تور من أجل الخصوصية</string>
   <string name="tor_network_setting">وسيلة الاتصال لشبكة تور</string>
   <string name="tor_network_setting_automatic">تلقائيًا حسب الموقع</string>
+  <string name="tor_network_setting_without_bridges">استخدام شبكة تور من دون جسور</string>
+  <string name="tor_network_setting_with_bridges">استخدام شبكة تور مع جسور</string>
   <string name="tor_network_setting_never">لا يمكن الاتصال بالإنترنت</string>
   <!--How and when Briar will connect to Tor: E.g. "Don't connect to the Internet (in China)" or "Use Tor network with bridges (in Belarus)"-->
   <string name="tor_network_setting_summary">تلقائيا: %1$s (في %2$s)</string>
@@ -574,6 +601,7 @@
   <string name="lock_is_locked">Briar (براير) مقفل</string>
   <string name="lock_tap_to_unlock">الرجاء اللمس لفك القفل</string>
   <!--Connections Screen-->
+  <string name="transports_help_text">يمكن ل Briar التواصل مع جهات الاتصال عن طريق الانترنت, شكبة ال Wi-Fi أو البلوتوث.n\n\كل وسائل الاتصال عن طريق الانترنت تمر عبر شبكة تور من أجل الخصوصية.n\n\إذا كان من الممكن الوصول إلى شبكة إتصال بعدة طرق فإن Briar سوف يستعملهم جميعاً بالتوازي.</string>
   <!--Screenshots-->
   <!--This is a name to be used in screenshots. Feel free to change it to a local name.-->
   <string name="screenshot_alice">آليس</string>

briar-android/src/main/res/values-de/strings.xml

@@ -211,7 +211,7 @@
   <string name="add_contact_choose_nickname">Wähle einen Spitznamen</string>
   <string name="add_contact_choose_a_nickname">Gib einen Spitznamen ein</string>
   <string name="nickname_intro">Gib deinem Kontakt einen Spitznamen. Nur du kannst ihn sehen.</string>
-  <string name="your_link">Gebe diesen Link dem Kontakt, den du hinzufügen möchtest:</string>
+  <string name="your_link">Gib diesen Link dem Kontakt, den du hinzufügen möchtest</string>
   <string name="link_clip_label">Briar Link</string>
   <string name="link_copied_toast">Link kopiert</string>
   <string name="adding_contact_error">Es gab einen Fehler beim Hinzufügen des Kontaktes.</string>

briar-android/src/main/res/values-es/strings.xml

@@ -157,12 +157,12 @@
   <string name="dialog_message_delete_all_messages">¿Estás seguro de que deseas eliminar todos los mensajes?</string>
   <string name="dialog_title_not_all_messages_deleted">No se pudieron eliminar todos los mensajes.</string>
   <string name="dialog_message_not_deleted_ongoing_both">Los mensajes relacionados con presentaciones o invitaciones en curso no se pueden eliminar hasta que finalicen.</string>
-  <string name="dialog_message_not_deleted_ongoing_introductions">Los mensajes relacionados con presentaciones o invitaciones en curso no se pueden eliminar hasta que finalicen.</string>
+  <string name="dialog_message_not_deleted_ongoing_introductions">Los mensajes relacionados con presentaciones no se pueden eliminar hasta que finalicen.</string>
   <string name="dialog_message_not_deleted_ongoing_invitations">Los mensajes relacionados a invitaciones en curso no pueden ser borrados hasta su conclusión.</string>
   <string name="dialog_message_not_deleted_partly_downloaded">Los mensajes parcialmente descargados no se pueden eliminar hasta que haya finalizado la descarga.</string>
   <string name="dialog_message_not_deleted_not_all_selected_both">Para borrar una invitación o presentación, debes seleccionar la petición y la respuesta.</string>
-  <string name="dialog_message_not_deleted_not_all_selected_introductions">Para eliminar una introducción, debe seleccionar la solicitud y la respuesta.</string>
-  <string name="dialog_message_not_deleted_not_all_selected_invitations">Para eliminar una invitación, debe seleccionar la solicitud y la respuesta.</string>
+  <string name="dialog_message_not_deleted_not_all_selected_introductions">Para eliminar una introducción, debes seleccionar la solicitud y la respuesta.</string>
+  <string name="dialog_message_not_deleted_not_all_selected_invitations">Para eliminar una invitación, debes seleccionar la solicitud y la respuesta.</string>
   <string name="delete_contact">Eliminar contacto</string>
   <string name="dialog_title_delete_contact">Confirmar eliminación de contacto</string>
   <string name="dialog_message_delete_contact">¿Seguro que quieres eliminar este contacto y todos los mensajes intercambiados entre vosotros?</string>

briar-android/src/main/res/values-fr/strings.xml

@@ -31,7 +31,7 @@
   <string name="sign_in_button">Connexion</string>
   <string name="forgotten_password">J’ai oublié mon mot de passe</string>
   <string name="dialog_title_lost_password">Mot de passe oublié</string>
-  <string name="dialog_message_lost_password">Votre compte Briar est enregistré chiffré sur votre appareil, pas dans le nuage, et nous ne pouvons donc pas réinitialiser votre mot de passe. Souhaitez-vous supprimer votre compte et recommencer ?\n\nAttention : vos identités, contacts et messages seront perdus irrémédiablement.</string>
+  <string name="dialog_message_lost_password">Votre compte Briar est enregistré chiffré sur votre appareil, pas dans le nuage, et nous ne pouvons donc pas réinitialiser votre mot de passe. Voulez-vous supprimer votre compte et recommencer ?\n\nAttention : vos identités, contacts et messages seront perdus irrémédiablement.</string>
   <string name="startup_failed_notification_title">Impossible de démarrer Briar</string>
   <string name="startup_failed_notification_text">Toucher pour plus d’informations.</string>
   <string name="startup_failed_activity_title">Échec de démarrage de Briar</string>
@@ -143,7 +143,7 @@
   <string name="no_contacts_action">Touchez l’icône + pour ajouter un contact</string>
   <string name="date_no_private_messages">Aucun message.</string>
   <string name="no_private_messages">Aucun message à afficher</string>
-  <string name="message_hint">Rédiger le message</string>
+  <string name="message_hint">Rédigez un message</string>
   <string name="image_caption_hint">Ajouter une légende (facultatif)</string>
   <string name="image_attach">Joindre une image</string>
   <string name="image_attach_error">Impossible de joindre une ou des images</string>
@@ -154,7 +154,7 @@
   <string name="set_alias_button">Modifier</string>
   <string name="delete_all_messages">Supprimer tous les messages</string>
   <string name="dialog_title_delete_all_messages">Confirmer la suppression des messages</string>
-  <string name="dialog_message_delete_all_messages">Souhaitez-vous vraiment supprimer tous les messages ?</string>
+  <string name="dialog_message_delete_all_messages">Voulez-vous vraiment supprimer tous les messages ?</string>
   <string name="dialog_title_not_all_messages_deleted">Impossible de supprimer tous les messages</string>
   <string name="dialog_message_not_deleted_ongoing_both">Les messages relatifs aux invitations et présentations en cours ne peuvent pas être supprimés jusqu’à leur conclusion.</string>
   <string name="dialog_message_not_deleted_ongoing_introductions">Les messages relatifs aux présentations en cours ne peuvent pas être supprimés jusqu’à leur conclusion.</string>
@@ -165,13 +165,13 @@
   <string name="dialog_message_not_deleted_not_all_selected_invitations">Pour supprimer une invitation, vous devez sélectionner la demande et la réponse.</string>
   <string name="delete_contact">Supprimer le contact</string>
   <string name="dialog_title_delete_contact">Confirmer la suppression du contact</string>
-  <string name="dialog_message_delete_contact">Souhaitez-vous vraiment supprimer ce contact et tous les messages associés ?</string>
+  <string name="dialog_message_delete_contact">Voulez-vous vraiment supprimer ce contact et tous les messages associés ?</string>
   <string name="contact_deleted_toast">Le contact a été supprimé</string>
   <!--This is shown in the action bar when opening an image in fullscreen that the user sent-->
   <string name="you">Vous</string>
   <string name="save_image">Enregistrer l’image</string>
   <string name="dialog_title_save_image">Enregistrer l’image ?</string>
-  <string name="dialog_message_save_image">L’enregistrement de cette image permettra aux autres applis d’y accéder.\n\n Souhaitez-vous vraiment l’enregistrer ?</string>
+  <string name="dialog_message_save_image">L’enregistrement de cette image permettra aux autres applis d’y accéder.\n\n Voulez-vous vraiment l’enregistrer ?</string>
   <string name="save_image_success">L’image a été enregistrée</string>
   <string name="save_image_error">Impossible d’enregistrer l’image</string>
   <string name="dialog_title_no_image_support">Les images ne sont pas disponibles</string>
@@ -266,7 +266,7 @@
   <string name="introduction_sent">Votre présentation a été envoyée.</string>
   <string name="introduction_error">Une erreur est survenue lors de la présentation.</string>
   <string name="introduction_request_sent">Vous avez demandé de présenter %1$s à %2$s.</string>
-  <string name="introduction_request_received">%1$s a demandé de vous présenter à %2$s. Souhaitez-vous ajouter %2$s à votre liste de contacts ?</string>
+  <string name="introduction_request_received">%1$s a demandé de vous présenter à %2$s. Voulez-vous ajouter %2$s à votre liste de contacts ?</string>
   <string name="introduction_request_exists_received">%1$s a demandé de vous présenter à %2$s, mais %2$s est déjà dans votre liste de contacts. Puisque %1$s pourrait ne pas le savoir, vous pouvez tout de même répondre :</string>
   <string name="introduction_request_answered_received">%1$s a demandé de vous présenter à %2$s.</string>
   <string name="introduction_response_accepted_sent">Vous avez accepté d’être présenté à %1$s.</string>
@@ -299,10 +299,10 @@
   <string name="groups_member_joined">%s s’est joint au groupe</string>
   <string name="groups_leave">Quitter le groupe</string>
   <string name="groups_leave_dialog_title">Confirmer la sortie du groupe</string>
-  <string name="groups_leave_dialog_message">Souhaitez-vous vraiment quitter ce groupe ?</string>
+  <string name="groups_leave_dialog_message">Voulez-vous vraiment quitter ce groupe ?</string>
   <string name="groups_dissolve">Dissoudre le groupe</string>
   <string name="groups_dissolve_dialog_title">Confirmer la dissolution du groupe</string>
-  <string name="groups_dissolve_dialog_message">Souhaitez-vous vraiment dissoudre ce groupe ?\n\nLes autres participants ne pourront pas poursuivre leur conversation et ne recevront peut-être pas les derniers messages.</string>
+  <string name="groups_dissolve_dialog_message">Voulez-vous vraiment dissoudre ce groupe ?\n\nLes autres participants ne pourront pas poursuivre leur conversation et ne recevront peut-être pas les derniers messages.</string>
   <string name="groups_dissolve_button">Dissoudre</string>
   <string name="groups_dissolved_dialog_title">Le groupe a été dissous</string>
   <string name="groups_dissolved_dialog_message">Le créateur de ce groupe l’a dissous.\n\nVous ne pouvez plus écrire de messages au groupe et ne recevrez peut-être pas tous ceux qui y ont été publiés.</string>
@@ -346,7 +346,7 @@
   <string name="btn_reply">Répondre</string>
   <string name="forum_leave">Quitter le forum</string>
   <string name="dialog_title_leave_forum">Confirmer la sortie du forum</string>
-  <string name="dialog_message_leave_forum">Souhaitez-vous vraiment quitter ce forum ?\n\nLes contacts avec qui vous l’avez partagé pourraient ne plus en recevoir les mises à jour.</string>
+  <string name="dialog_message_leave_forum">Voulez-vous vraiment quitter ce forum ?\n\nLes contacts avec qui vous l’avez partagé pourraient ne plus en recevoir les mises à jour.</string>
   <string name="dialog_button_leave">Quitter</string>
   <string name="forum_left_toast">À quitté le forum</string>
   <!--Forum Sharing-->
@@ -390,7 +390,7 @@
   <string name="blogs_feed_empty_state">Aucun billet à afficher</string>
   <string name="blogs_feed_empty_state_action">Les billets de vos contacts et les blogues auxquels vous vous abonnez apparaîtront ici.\n\nTouchez l’icône de crayon pour rédiger un billet</string>
   <string name="blogs_remove_blog">Supprimer le blogue</string>
-  <string name="blogs_remove_blog_dialog_message">Souhaitez-vous vraiment supprimer ce blogue ?\nLes billets seront supprimés de votre appareil mais pas des appareils d’autrui.\n\nLes contacts avec qui vous avez partagé ce blogue pourraient ne plus en recevoir les mises à jour.</string>
+  <string name="blogs_remove_blog_dialog_message">Voulez-vous vraiment supprimer ce blogue ?\nLes billets seront supprimés de votre appareil mais pas des appareils d’autrui.\n\nLes contacts avec qui vous avez partagé ce blogue pourraient ne plus en recevoir les mises à jour.</string>
   <string name="blogs_remove_blog_ok">Supprimer</string>
   <string name="blogs_blog_removed">Le blogue a été supprimé</string>
   <string name="blogs_reblog_comment_hint">Ajouter un commentaire (facultatif)</string>
@@ -420,7 +420,7 @@
   <string name="blogs_rss_feeds_manage_author">Auteur :</string>
   <string name="blogs_rss_feeds_manage_updated">Dernière mise à jour :</string>
   <string name="blogs_rss_remove_feed">Supprimer le fil</string>
-  <string name="blogs_rss_remove_feed_dialog_message">Souhaitez-vous vraiment supprimer ce fil ?\nLes billets seront supprimés de votre appareil mais pas des appareils d’autrui.\n\nLes contacts avec qui vous avez partagé ce fil pourraient ne plus en recevoir les mises à jour.</string>
+  <string name="blogs_rss_remove_feed_dialog_message">Voulez-vous vraiment supprimer ce fil ?\nLes billets seront supprimés de votre appareil mais pas des appareils d’autrui.\n\nLes contacts avec qui vous avez partagé ce fil pourraient ne plus en recevoir les mises à jour.</string>
   <string name="blogs_rss_remove_feed_ok">Supprimer</string>
   <string name="blogs_rss_feeds_manage_delete_error">Impossible de supprimer le fil !</string>
   <string name="blogs_rss_feeds_manage_empty_state">Aucun fil RSS à afficher\n\nTouchez l’icône + pour importer un fil</string>
@@ -484,7 +484,7 @@
   <string name="panic_app_setting_summary">Aucune appli n’a été définie</string>
   <string name="panic_app_setting_none">Aucune</string>
   <string name="dialog_title_connect_panic_app">Confirmer l’application d’urgence</string>
-  <string name="dialog_message_connect_panic_app">Souhaitez-vous vraiment autoriser %1$s à déclencher les actions destructrices du bouton d’urgence ?</string>
+  <string name="dialog_message_connect_panic_app">Voulez-vous vraiment autoriser %1$s à déclencher les actions destructrices du bouton d’urgence ?</string>
   <string name="panic_setting_destructive_action">Actions destructrices</string>
   <string name="panic_setting_signout_title">Déconnexion</string>
   <string name="panic_setting_signout_summary">Se déconnecter de Briar si l’on appuie sur un bouton d’urgence</string>

briar-android/src/main/res/values-gl/strings.xml

@@ -61,12 +61,36 @@
   <string name="lock_button">Bloquear App</string>
   <string name="settings_button">Axustes</string>
   <string name="sign_out_button">Finalizar sesión</string>
+  <string name="transports_onboarding_text">Toca aquí para controlar o xeito en que Briar conecta cos teus contactos.</string>
   <!--Transports: Tor-->
   <string name="transport_tor">Internet</string>
+  <string name="tor_device_status_online_wifi">O teu móbil ten acceso a internet por Wi-Fi</string>
+  <string name="tor_device_status_online_mobile">O teu móbil ten acceso a internet por datos móbiles</string>
+  <string name="tor_device_status_offline">O teu móbil non ten acceso a internet</string>
+  <string name="tor_plugin_status_enabling">Briar estase conectando a internet</string>
+  <string name="tor_plugin_status_active">Briar está conectada a internet</string>
+  <string name="tor_plugin_status_inactive">Briar non pode conectarse a internet</string>
+  <string name="tor_plugin_status_disabled">Briar está configurada para non usar internet</string>
+  <string name="tor_plugin_status_disabled_mobile_data">Briar está configurada para non usar datos móbilies</string>
+  <string name="tor_plugin_status_disabled_battery">Briar está configurada para non usar internet se está usando batería</string>
+  <string name="tor_plugin_status_disabled_country_blocked">Briar está configurada para non usar internet neste país</string>
   <!--Transports: Wi-Fi-->
   <string name="transport_lan">Wi-Fi</string>
+  <string name="transport_lan_long">Mesma rede Wi-Fi</string>
+  <string name="lan_device_status_on">O móbil está conectado á Wi-Fi</string>
+  <string name="lan_device_status_off">O móbil non está conectado á Wi-Fi</string>
+  <string name="lan_plugin_status_enabling">Briar está conectando á rede Wi-Fi</string>
+  <string name="lan_plugin_status_active">Briar está conectada á rede Wi-Fi</string>
+  <string name="lan_plugin_status_inactive">Briar non pode conectar coa rede Wi-Fi</string>
+  <string name="lan_plugin_status_disabled">Briar está configurada para non usar a rede Wi-Fi</string>
   <!--Transports: Bluetooth-->
   <string name="transport_bt">Bluetooth</string>
+  <string name="bt_device_status_on">O móbil ten o Bluetooth activado</string>
+  <string name="bt_device_status_off">O móbil ten o Bluetooth desactivado</string>
+  <string name="bt_plugin_status_enabling">Briar está conectando por Bluetooth</string>
+  <string name="bt_plugin_status_active">Briar está conectada ó Bluetooth</string>
+  <string name="bt_plugin_status_inactive">Briar non pode conectar por Bluetooth</string>
+  <string name="bt_plugin_status_disabled">Briar está configurada para non usar Bluetooth</string>
   <!--Notifications-->
   <string name="reminder_notification_title">Desconectou de Briar</string>
   <string name="reminder_notification_text">Toque para voltar a conectar</string>
@@ -536,6 +560,7 @@
   <string name="lock_is_locked">Briar está bloqueada</string>
   <string name="lock_tap_to_unlock">Toque para desbloquear</string>
   <!--Connections Screen-->
+  <string name="transports_help_text">Briar pode conectar cos teus contactos a través de Internet, Wi-Fi ou Bluetooth.\n\nTodas as conexións a internet pasan a través da rede Tor para máis privacidade.\n\nSe un contacto é accesible de múltiples xeitos, Briar usaráos en paralelo.</string>
   <!--Screenshots-->
   <!--This is a name to be used in screenshots. Feel free to change it to a local name.-->
   <string name="screenshot_alice">Alice</string>

briar-android/src/main/res/values-hu/strings.xml

@@ -61,12 +61,36 @@
   <string name="lock_button">App zárolása</string>
   <string name="settings_button">Beállítások</string>
   <string name="sign_out_button">Kijelentkezés</string>
+  <string name="transports_onboarding_text">Érintse meg itt, hogy beállíthassa, hogyan csatlakozzon a Tor kapcsolataihoz.</string>
   <!--Transports: Tor-->
   <string name="transport_tor">Internet</string>
+  <string name="tor_device_status_online_wifi">A telefonja Internet hozzáféréssel rendelkezik Wi-Fi-n keresztül</string>
+  <string name="tor_device_status_online_mobile">A telefonja Internet hozzáféréssel rendelkezik mobil hálózaton keresztül</string>
+  <string name="tor_device_status_offline">A telefonja nem rendelkezik Internet hozzáféréssel</string>
+  <string name="tor_plugin_status_enabling">A Briar csatlakozik az Internethez</string>
+  <string name="tor_plugin_status_active">A Briar csatlakoztatva az Internethez</string>
+  <string name="tor_plugin_status_inactive">A Briar nem tud csatlakozni az Internethez</string>
+  <string name="tor_plugin_status_disabled">A Briar Internet nélküli használatra van beállítva</string>
+  <string name="tor_plugin_status_disabled_mobile_data">A Briar mobil hálózat nélküli használatra van beállítva</string>
+  <string name="tor_plugin_status_disabled_battery">A Briar úgy van beállítva, hogy ne használjon Internetet, ha akkumulátorról megy a telefon</string>
+  <string name="tor_plugin_status_disabled_country_blocked">A Briar úgy van beállítva, hogy ne használjon Internetet ebben az országban</string>
   <!--Transports: Wi-Fi-->
   <string name="transport_lan">Wi-Fi</string>
+  <string name="transport_lan_long">Azonos Wi-Fi hálózat</string>
+  <string name="lan_device_status_on">A telefonja Wi-Fi-hez csatlakoztatott.</string>
+  <string name="lan_device_status_off">A telefonja Wi-Fi-hez nem csatlakoztatott.</string>
+  <string name="lan_plugin_status_enabling">A Briar csatlakozik a Wi-Fi hálózathoz</string>
+  <string name="lan_plugin_status_active">A Briar csatlakoztatva a Wi-Fi hálózathoz</string>
+  <string name="lan_plugin_status_inactive">A Briar nem tud csatlakozni a Wi-Fi hálózathoz</string>
+  <string name="lan_plugin_status_disabled">A Briar Wi-Fi nélküli használatra van beállítva</string>
   <!--Transports: Bluetooth-->
   <string name="transport_bt">Bluetooth</string>
+  <string name="bt_device_status_on">A telefonja Bluetooth-ja bekapcsolva</string>
+  <string name="bt_device_status_off">A telefonja Bluetooth-ja kikapcsolva</string>
+  <string name="bt_plugin_status_enabling">A Briar csatlakozik a Bluetooth-hoz</string>
+  <string name="bt_plugin_status_active">A Briar csatlakoztatva a Bluetooth-hoz</string>
+  <string name="bt_plugin_status_inactive">A Briar nem tud csatlakozni a Bluetooth-hoz</string>
+  <string name="bt_plugin_status_disabled">A Briar Bluetooth nélküli használatra van beállítva</string>
   <!--Notifications-->
   <string name="reminder_notification_title">Kilépve a Briar-ból</string>
   <string name="reminder_notification_text">Érintse meg az újra belépéshez.</string>
@@ -421,10 +445,19 @@ Kapcsolatai, akivel megosztotta ezt a blogot, lehet nem kapnak többé frissít
   <string name="pref_theme_system">Rendszer alapértelmezett</string>
   <!--Settings Connections-->
   <string name="network_settings_title">Kapcsolatok</string>
+  <string name="bluetooth_setting">Csatlakozás a kapcsolatokhoz Bluetooth-on</string>
+  <string name="wifi_setting">Csatlakozás az egy Wi-Fi hálózaton lévő kapcsolatokhoz</string>
+  <string name="tor_enable_title">Csatlakozás a kapcsolatokhoz Interneten</string>
+  <string name="tor_enable_summary">Minden kapcsolat átmegy a Tor hálózaton az adatvédelem érdekében</string>
+  <string name="tor_network_setting">Kapcsolódási mód a Tor hálózathoz</string>
   <string name="tor_network_setting_automatic">Automatikusan hely alapján</string>
+  <string name="tor_network_setting_without_bridges">Tor hálózat használata hidak nélkül</string>
+  <string name="tor_network_setting_with_bridges">Tor hálózat használata hidakkal</string>
+  <string name="tor_network_setting_never">Ne csatlakozzon az internethez</string>
   <!--How and when Briar will connect to Tor: E.g. "Don't connect to the Internet (in China)" or "Use Tor network with bridges (in Belarus)"-->
   <string name="tor_network_setting_summary">Automatikus: %1$s ( %2$s)</string>
   <string name="tor_mobile_data_title">Mobil adat használata</string>
+  <string name="tor_only_when_charging_title">Csatlakozás az internethez csak töltés alatt</string>
   <string name="tor_only_when_charging_summary">Letiltja az internet kapcsolatot, amikor elemről fut az eszköz</string>
   <!--Settings Security and Panic-->
   <string name="security_settings_title">Biztonság</string>
@@ -536,6 +569,7 @@ Vigyázat: Ez végleg törli az identitásait, kapcsolatait és üzeneteit</stri
   <string name="lock_is_locked">A Briar zárolt</string>
   <string name="lock_tap_to_unlock">Érintse meg a zárolás feloldásához</string>
   <!--Connections Screen-->
+  <string name="transports_help_text">A Briar Interneten, Wi-Fi-n vagy Bluetooth-on keresztül csatlakozhat kapcsolataihoz.\n\nAz összes internetkapcsolat a Tor hálózaton megy keresztül megy az adatvédelem érdekében.\n\nHa egy kapcsolatot több módszerrel is el lehet érni, Briar párhuzamosan használja azokat.</string>
   <!--Screenshots-->
   <!--This is a name to be used in screenshots. Feel free to change it to a local name.-->
   <string name="screenshot_alice">Alice</string>

briar-android/src/main/res/values-is/strings.xml

@@ -79,8 +79,18 @@
   <string name="transport_lan_long">Sama þráðlausa Wi-Fi netkerfið</string>
   <string name="lan_device_status_on">Síminn þinn er tengdur við Wi-Fi</string>
   <string name="lan_device_status_off">Síminn þinn er ekki tengdur við Wi-Fi</string>
+  <string name="lan_plugin_status_enabling">Briar er að tengjast við Wi-Fi-netið</string>
+  <string name="lan_plugin_status_active">Briar er tengt við við Wi-Fi-netið</string>
+  <string name="lan_plugin_status_inactive">Briar getur ekki tengst við Wi-Fi-netið</string>
+  <string name="lan_plugin_status_disabled">Briar er sett upp til að nota ekki Wi-Fi-netið</string>
   <!--Transports: Bluetooth-->
   <string name="transport_bt">Bluetooth</string>
+  <string name="bt_device_status_on">Kveikt er á Bluetooth-kerfi símans</string>
+  <string name="bt_device_status_off">Slökkt er á Bluetooth-kerfi símans</string>
+  <string name="bt_plugin_status_enabling">Briar er að tengjast við Bluetooth</string>
+  <string name="bt_plugin_status_active">Briar er tengt við Bluetooth</string>
+  <string name="bt_plugin_status_inactive">Briar getur ekki tengst við Bluetooth</string>
+  <string name="bt_plugin_status_disabled">Briar er sett upp til að nota ekki Bluetooth</string>
   <!--Notifications-->
   <string name="reminder_notification_title">Skráð út úr Briar</string>
   <string name="reminder_notification_text">Ýttu til að skrá þig aftur inn.</string>
@@ -426,19 +436,29 @@
   <string name="pref_theme_auto">Sjálfvirkt (eftir tíma dags)</string>
   <string name="pref_theme_system">Sjálfgefið í kerfinu</string>
   <!--Settings Connections-->
+  <string name="network_settings_title">Tengingar</string>
+  <string name="bluetooth_setting">Tengjast tengiliðum í gegnum Bluetooth</string>
+  <string name="wifi_setting">Tengjast tengiliðum á sama þráðlausa Wi-Fi neti</string>
+  <string name="tor_enable_title">Tengjast tengiliðum í gegnum internetið</string>
+  <string name="tor_enable_summary">Allar tengingar fara í gegnum Tor-netið til að vernda persónuupplýsingar</string>
+  <string name="tor_network_setting">Aðferðir til tengingar við Tor-netið</string>
   <string name="tor_network_setting_automatic">Sjálfvirkt byggt á staðsetningu</string>
+  <string name="tor_network_setting_without_bridges">Nota Tor-netkerfið án brúa</string>
+  <string name="tor_network_setting_with_bridges">Nota Tor-netkerfið með brúm</string>
+  <string name="tor_network_setting_never">Ekki tengjast við internetið</string>
   <!--How and when Briar will connect to Tor: E.g. "Don't connect to the Internet (in China)" or "Use Tor network with bridges (in Belarus)"-->
   <string name="tor_network_setting_summary">Sjálfvirkt: %1$s (eftir %2$s)</string>
   <string name="tor_mobile_data_title">Nota farsímagagnasamband</string>
+  <string name="tor_only_when_charging_title">Tengjast í gegnum internetið aðeins þegar verið er í hleðslu</string>
   <string name="tor_only_when_charging_summary">Gerir internettengingu óvirka þegar tækið keyrir á rafhlöðu</string>
   <!--Settings Security and Panic-->
   <string name="security_settings_title">Öryggi</string>
   <string name="pref_lock_title">Forritslæsing</string>
   <string name="pref_lock_summary">Notaðu skjálæsingu tækisins til að vernda Briar á meðan þú ert skráð/ur inn</string>
   <string name="pref_lock_disabled_summary">Til að nota þetta þarftu að setja upp skjálæsingu fyrir tækið þitt</string>
-  <string name="pref_lock_timeout_title">Tímamörk forritslæsingar við aðgerðaleysi</string>
+  <string name="pref_lock_timeout_title">Tímamörk læsingar forrits við aðgerðaleysi</string>
   <!--The %s placeholder is replaced with the following time spans, e.g. 5 Minutes, 1 Hour-->
-  <string name="pref_lock_timeout_summary">Þehar ekki er verið að nota Briar, læsa því sjálfvirkt eftir %s</string>
+  <string name="pref_lock_timeout_summary">Þegar ekki er verið að nota Briar, læsa því sjálfvirkt eftir %s</string>
   <!--Will be shown in a list of lock times. Should fit into the %s of "automatically lock it after %s"-->
   <string name="pref_lock_timeout_1">1 mínúta</string>
   <!--Will be shown in a list of lock times. Should fit into the %s of "automatically lock it after %s"-->
@@ -540,6 +560,7 @@
   <string name="lock_is_locked">Briar er læst</string>
   <string name="lock_tap_to_unlock">Ýttu til að aflæsa</string>
   <!--Connections Screen-->
+  <string name="transports_help_text">Briar getur tengst við tengiliðina þína í gegnum internet, Wi-Fi eða Bluetooth.\n\nAllar internettengingar fara í gegnum Tor-netkerfið til að gæta gagnaleyndar.\n\nEf hægt er að nálgast tengilið með mörgum leiðum, notar Briar þær samhliða.</string>
   <!--Screenshots-->
   <!--This is a name to be used in screenshots. Feel free to change it to a local name.-->
   <string name="screenshot_alice">Lísa</string>

briar-android/src/main/res/values-nl/strings.xml

@@ -61,12 +61,36 @@
   <string name="lock_button">App vergrendelen</string>
   <string name="settings_button">Instellingen</string>
   <string name="sign_out_button">Log uit</string>
+  <string name="transports_onboarding_text">Tik hier om in te stellen hoe Briar een verbinding met je contacten opzet.</string>
   <!--Transports: Tor-->
   <string name="transport_tor">Internet</string>
+  <string name="tor_device_status_online_wifi">Je apparaat heeft internettoegang via wifi</string>
+  <string name="tor_device_status_online_mobile">Je apparaat heeft internettoegang via mobiele dataverbinding</string>
+  <string name="tor_device_status_offline">Je apparaat heeft geen internettoegang</string>
+  <string name="tor_plugin_status_enabling">Briar is aan het verbinden met internet</string>
+  <string name="tor_plugin_status_active">Briar is verbonden met het internet</string>
+  <string name="tor_plugin_status_inactive">Briar kan geen verbinding maken met het internet</string>
+  <string name="tor_plugin_status_disabled">Briar is geconfigureerd om internet niet te gebruiken</string>
+  <string name="tor_plugin_status_disabled_mobile_data">Briar is geconfigureerd om mobiele dataverbinding niet te gebruiken</string>
+  <string name="tor_plugin_status_disabled_battery">Briar is geconfigureerd om het internet niet te gebruiken als apparaat op baterij loopt</string>
+  <string name="tor_plugin_status_disabled_country_blocked">Briar is geconfigureerd om internet niet te gebruiken in dit land</string>
   <!--Transports: Wi-Fi-->
   <string name="transport_lan">Wifi</string>
+  <string name="transport_lan_long">Hetzelfde wifinetwerk</string>
+  <string name="lan_device_status_on">Je apparaat is verbonden met wifi</string>
+  <string name="lan_device_status_off">Je apparaat is niet verbonden met wifi</string>
+  <string name="lan_plugin_status_enabling">Briar is verbinding aan het maken met het wifinetwerk</string>
+  <string name="lan_plugin_status_active">Briar is verbonden met het wifinetwerk</string>
+  <string name="lan_plugin_status_inactive">Briar kan geen verbinding maken met het wifinetwerk</string>
+  <string name="lan_plugin_status_disabled">Briar is geconfigureerd om het wifinetwerk niet te gebruiken</string>
   <!--Transports: Bluetooth-->
   <string name="transport_bt">Bluetooth</string>
+  <string name="bt_device_status_on">Bluetooth op je apparaat staat aan</string>
+  <string name="bt_device_status_off">Bluetooth op je apparaat staat uit</string>
+  <string name="bt_plugin_status_enabling">Briar is aan het verbinden met bluetooth</string>
+  <string name="bt_plugin_status_active">Briar is verbonden met bluetooth</string>
+  <string name="bt_plugin_status_inactive">Briar kan geen verbinding maken met bluetooth</string>
+  <string name="bt_plugin_status_disabled">Briar is geconfigureerd om bluetooth niet te gebruiken</string>
   <!--Notifications-->
   <string name="reminder_notification_title">Uitgelogd van Briar</string>
   <string name="reminder_notification_text">Tik om opnieuw in te loggen.</string>
@@ -536,6 +560,7 @@
   <string name="lock_is_locked">Briar is vergrendeld</string>
   <string name="lock_tap_to_unlock">Tik om te ontgrendelen</string>
   <!--Connections Screen-->
+  <string name="transports_help_text">Briar kan met je contacten verbinden via het internet, wifi of bluetooth.\n\nAlle internetverbindingen gaan voor privacy door het Tornetwerk.\n\nAls een contact via meerdere methoden te bereiken is, zal Briar die parallel gebruiken.</string>
   <!--Screenshots-->
   <!--This is a name to be used in screenshots. Feel free to change it to a local name.-->
   <string name="screenshot_alice">Veerle</string>

briar-android/src/main/res/values-pt-rBR/strings.xml

@@ -61,6 +61,7 @@
   <string name="lock_button">Bloquear Aplicativo</string>
   <string name="settings_button">Configurações</string>
   <string name="sign_out_button">Sair</string>
+  <string name="transports_onboarding_text">Clique aqui para controlar como o Briar se conecta aos seus contatos.</string>
   <!--Transports: Tor-->
   <string name="transport_tor">Internet</string>
   <!--Transports: Wi-Fi-->

briar-android/src/main/res/values-ru/strings.xml

@@ -65,12 +65,36 @@
   <string name="lock_button">Заблокировать приложение</string>
   <string name="settings_button">Настройки</string>
   <string name="sign_out_button">Выйти</string>
+  <string name="transports_onboarding_text">Нажмите здесь, чтобы проверить, как Briar подключается к вашим контактам.</string>
   <!--Transports: Tor-->
   <string name="transport_tor">Интернет</string>
+  <string name="tor_device_status_online_wifi">Ваш телефон имеет доступ в интернет через Wi-Fi</string>
+  <string name="tor_device_status_online_mobile">Ваш телефон имеет доступ в интернет через мобильную сеть.</string>
+  <string name="tor_device_status_offline">Ваш телефон не имеет доступа в интернет</string>
+  <string name="tor_plugin_status_enabling">Briar подключается к интернету</string>
+  <string name="tor_plugin_status_active">Briar подключен к интернету</string>
+  <string name="tor_plugin_status_inactive">Briar не может подключиться к интернету.</string>
+  <string name="tor_plugin_status_disabled">Briar настроен не использовать интернет</string>
+  <string name="tor_plugin_status_disabled_mobile_data">Briar настроен не использовать мобильную сеть</string>
+  <string name="tor_plugin_status_disabled_battery">Briar настроен не использовать интернет при работе от батареи</string>
+  <string name="tor_plugin_status_disabled_country_blocked">Briar настроен не использовать интернет в этой стране</string>
   <!--Transports: Wi-Fi-->
   <string name="transport_lan">Wi-Fi</string>
+  <string name="transport_lan_long">Та же сеть Wi-Fi</string>
+  <string name="lan_device_status_on">Ваш телефон подключен к Wi-Fi</string>
+  <string name="lan_device_status_off">Телефон не подключен к Wi-Fi</string>
+  <string name="lan_plugin_status_enabling">Briar подключается к сети Wi-Fi</string>
+  <string name="lan_plugin_status_active">Briar подключен к сети Wi-Fi</string>
+  <string name="lan_plugin_status_inactive">Briar не может подключиться к сети Wi-Fi.</string>
+  <string name="lan_plugin_status_disabled">Briar настроен не использовать сеть Wi-Fi.</string>
   <!--Transports: Bluetooth-->
   <string name="transport_bt">Bluetooth</string>
+  <string name="bt_device_status_on">Bluetooth вашего телефона включен.</string>
+  <string name="bt_device_status_off">Bluetooth вашего телефона отключен.</string>
+  <string name="bt_plugin_status_enabling">Briar подключается к Bluetooth</string>
+  <string name="bt_plugin_status_active">Briar подключен к Bluetooth</string>
+  <string name="bt_plugin_status_inactive">Briar не может подключиться к Bluetooth.</string>
+  <string name="bt_plugin_status_disabled">Briar настроен не использовать Bluetooth</string>
   <!--Notifications-->
   <string name="reminder_notification_title">Вы не авторизованы в Briar</string>
   <string name="reminder_notification_text">Нажмите для входа</string>
@@ -199,7 +223,7 @@
   <string name="add_contact_choose_nickname">Выберите ник</string>
   <string name="add_contact_choose_a_nickname">Введите ник</string>
   <string name="nickname_intro">Дайте вашему контакту ник. Увидеть его сможете только вы.</string>
-  <string name="your_link">Передайте эту ссылку контакту, которого вы хотите добавить.</string>
+  <string name="your_link">Передайте эту ссылку контакту, который вы хотите добавить.</string>
   <string name="link_clip_label">Ссылка Briar</string>
   <string name="link_copied_toast">Ссылка скопирована</string>
   <string name="adding_contact_error">При добавлении контакта произошла ошибка.</string>
@@ -558,6 +582,7 @@
   <string name="lock_is_locked">Briar заблокирован</string>
   <string name="lock_tap_to_unlock">Нажмите для разблокировки</string>
   <!--Connections Screen-->
+  <string name="transports_help_text">Briar может подключаться к контактам через интернет, Wi-Fi или Bluetooth.\n\nВсе интернет-соединения проходят через сеть Tor для обеспечения конфиденциальности.\n\nЕсли с контактом можно связаться несколькими способами, Briar использует их параллельно.</string>
   <!--Screenshots-->
   <!--This is a name to be used in screenshots. Feel free to change it to a local name.-->
   <string name="screenshot_alice">Бузова</string>

briar-android/src/main/res/values-sv/strings.xml

@@ -61,12 +61,36 @@
   <string name="lock_button">Lås appen</string>
   <string name="settings_button">Inställningar</string>
   <string name="sign_out_button">Logga ut</string>
+  <string name="transports_onboarding_text">Klicka här för att styra hur Briar ansluter till dina kontakter.</string>
   <!--Transports: Tor-->
   <string name="transport_tor">Internet</string>
+  <string name="tor_device_status_online_wifi">Din telefon har internetåtkomst via Wi-Fi</string>
+  <string name="tor_device_status_online_mobile">Din telefon har internetåtkomst via mobildata</string>
+  <string name="tor_device_status_offline">Din telefon har inte internetåtkomst</string>
+  <string name="tor_plugin_status_enabling">Briar ansluter till internet</string>
+  <string name="tor_plugin_status_active">Briar är anslutet till internet</string>
+  <string name="tor_plugin_status_inactive">Briar kan inte ansluta till internet</string>
+  <string name="tor_plugin_status_disabled">Briar är inte konfigurerat för att använda internet</string>
+  <string name="tor_plugin_status_disabled_mobile_data">Briar är konfigurerat så att de inte använder mobildata</string>
+  <string name="tor_plugin_status_disabled_battery">Briar är konfigurerat att inte använda internet vid batterianvändning</string>
+  <string name="tor_plugin_status_disabled_country_blocked">Briar är konfigurerat att inte använda internet i detta landet</string>
   <!--Transports: Wi-Fi-->
   <string name="transport_lan">Wi-Fi</string>
+  <string name="transport_lan_long">Samma Wi-Fi-nätverk</string>
+  <string name="lan_device_status_on">Din telefon är ansluten till Wi-Fi</string>
+  <string name="lan_device_status_off">Din telefon är inte ansluten till Wi-Fi</string>
+  <string name="lan_plugin_status_enabling">Briar ansluter till Wi-Fi-nätverket</string>
+  <string name="lan_plugin_status_active">Briar är anslutet till Wi-Fi nätverket</string>
+  <string name="lan_plugin_status_inactive">Briar kan inte ansluta till Wi-Fi-nätverket</string>
+  <string name="lan_plugin_status_disabled">Briar är konfigurerat för att inte använda Wi-Fi-nätverket</string>
   <!--Transports: Bluetooth-->
   <string name="transport_bt">Bluetooth</string>
+  <string name="bt_device_status_on">Din telefons Bluetooth är aktiverad</string>
+  <string name="bt_device_status_off">Din telefons Bluetooth är inaktiverad</string>
+  <string name="bt_plugin_status_enabling">Briar ansluter till Bluetooth</string>
+  <string name="bt_plugin_status_active">Briar är ansluten till Bluetooth</string>
+  <string name="bt_plugin_status_inactive">Briar kan inte ansluta till Bluetooth</string>
+  <string name="bt_plugin_status_disabled">Briar är konfigurerat för att inte använda Bluetooth</string>
   <!--Notifications-->
   <string name="reminder_notification_title">Utloggad från Briar</string>
   <string name="reminder_notification_text">Tryck för att logga in igen.</string>
@@ -412,10 +436,20 @@
   <string name="pref_theme_auto">Automatisk (dagtid)</string>
   <string name="pref_theme_system">Systemets förval</string>
   <!--Settings Connections-->
+  <string name="network_settings_title">Anslutningar</string>
+  <string name="bluetooth_setting">Anslut till kontakter via Bluetooth</string>
+  <string name="wifi_setting">Anslut till kontakter på samma Wi-Fi-nätverk</string>
+  <string name="tor_enable_title">Anslut till kontakter via internet</string>
+  <string name="tor_enable_summary">Alla anslutningar gå via Tor-nätverket av integritetsskäl</string>
+  <string name="tor_network_setting">Anslutningsmetod för Tor-nätverket</string>
   <string name="tor_network_setting_automatic">Automatisk, baserad på position</string>
+  <string name="tor_network_setting_without_bridges">Använd Tor-nätverket utan bryggor</string>
+  <string name="tor_network_setting_with_bridges">Anvädn Tor-nätverket med bryggor</string>
+  <string name="tor_network_setting_never">Anslut inte till internet</string>
   <!--How and when Briar will connect to Tor: E.g. "Don't connect to the Internet (in China)" or "Use Tor network with bridges (in Belarus)"-->
   <string name="tor_network_setting_summary">Automatisk: %1$s (i %2$s)</string>
   <string name="tor_mobile_data_title">Använd mobildata</string>
+  <string name="tor_only_when_charging_title">Anslut till internet endast vid laddning</string>
   <string name="tor_only_when_charging_summary">Avaktiverar anslutning över Internet när enheten går på batteri</string>
   <!--Settings Security and Panic-->
   <string name="security_settings_title">Säkerhet</string>
@@ -526,6 +560,7 @@
   <string name="lock_is_locked">Briar är låst</string>
   <string name="lock_tap_to_unlock">Tryck för att låsa upp</string>
   <!--Connections Screen-->
+  <string name="transports_help_text">Briar kan ansluta till dina kontakter via internet, Wi-Fi eller Bluetooth.\n\nAlla internetanslutningar går via Tor-nätverket av integritetsskäl.\n\nOm en kontakt kan nås via flera metoder kommer Briar att använda dem parallellt.</string>
   <!--Screenshots-->
   <!--This is a name to be used in screenshots. Feel free to change it to a local name.-->
   <string name="screenshot_alice">Alice</string>

briar-android/src/main/res/values-tr/strings.xml

@@ -61,12 +61,36 @@
   <string name="lock_button">Uygulamayı Kilitle</string>
   <string name="settings_button">Ayarlar</string>
   <string name="sign_out_button">Oturumu Kapat</string>
+  <string name="transports_onboarding_text">Briar\'ın kişilerinizle nasıl bağlanacağını kontrol etmek için buraya tıklayın</string>
   <!--Transports: Tor-->
   <string name="transport_tor">İnternet</string>
+  <string name="tor_device_status_online_wifi">Telefonunuzun Wi-Fi aracılığıyla İnternet erişimi var</string>
+  <string name="tor_device_status_online_mobile">Telefonunuzun mobil veri aracılığıyla İnternet erişimi var</string>
+  <string name="tor_device_status_offline">Telefonunuzun İnternet erişimi yok</string>
+  <string name="tor_plugin_status_enabling">Briar İnternet\'e bağlanıyor</string>
+  <string name="tor_plugin_status_active">Briar İnternet\'e bağlandı</string>
+  <string name="tor_plugin_status_inactive">Briar İnternet\'e bağlanamıyor</string>
+  <string name="tor_plugin_status_disabled">Briar İnternet kullanmamak üzere yapılandırılmış</string>
+  <string name="tor_plugin_status_disabled_mobile_data">Briar mobil veri kullanmamak üzere yapılandırılmış</string>
+  <string name="tor_plugin_status_disabled_battery">Briar pille çalışırken İnternet kullanmamak üzere yapılandırılmış</string>
+  <string name="tor_plugin_status_disabled_country_blocked">Briar bu ülkede İnternet kullanmamak üzere yapılandırılmış</string>
   <!--Transports: Wi-Fi-->
   <string name="transport_lan">Wi-Fi</string>
+  <string name="transport_lan_long">Aynı Wi-Fi Ağı</string>
+  <string name="lan_device_status_on">Telefonunuz Wi-Fi\'ye bağlı</string>
+  <string name="lan_device_status_off">Telefonunuz Wi-Fi\'ye bağlı değil</string>
+  <string name="lan_plugin_status_enabling">Briar Wi-Fi ağına bağlanıyor</string>
+  <string name="lan_plugin_status_active">Briar Wi-Fi ağına bağlandı</string>
+  <string name="lan_plugin_status_inactive">Briar Wi-Fi ağına bağlanamıyor</string>
+  <string name="lan_plugin_status_disabled">Briar Wi-Fi ağını kullanmamak üzere yapılandırılmış</string>
   <!--Transports: Bluetooth-->
   <string name="transport_bt">Bluetooth</string>
+  <string name="bt_device_status_on">Telefonunuzun Bluetooth\'u açık</string>
+  <string name="bt_device_status_off">Telefonunuzun Bluetooth\'u kapalı</string>
+  <string name="bt_plugin_status_enabling">Briar Bluetooth\'a bağlanıyor</string>
+  <string name="bt_plugin_status_active">Briar Bluetooth\'a bağlandı</string>
+  <string name="bt_plugin_status_inactive">Briar Bluetooth\'a bağlanamıyor</string>
+  <string name="bt_plugin_status_disabled">Briar Bluetooth kullanmamak üzere yapılandırılmış</string>
   <!--Notifications-->
   <string name="reminder_notification_title">Briar oturumu kapatıldı</string>
   <string name="reminder_notification_text">Tekrar oturum açmak için dokunun</string>
@@ -536,6 +560,7 @@
   <string name="lock_is_locked">Briar kilitli</string>
   <string name="lock_tap_to_unlock">Kilidi açmak için dokunun</string>
   <!--Connections Screen-->
+  <string name="transports_help_text">Briar kişilerinizle İnternet, Wi-Fi veya Bluetooth ile bağlanabilir.\n\nBütün İnternet bağlantıları gizliliğiniz için Tor Ağı üzerinden yapılıyor.\n\nEğer bir kişiniz birçok yöntemle erişilebiliyorsa, Briar bu yöntemleri paralel olarak kullanır.</string>
   <!--Screenshots-->
   <!--This is a name to be used in screenshots. Feel free to change it to a local name.-->
   <string name="screenshot_alice">Alice</string>

briar-android/src/main/res/values-zh-rCN/strings.xml

@@ -60,12 +60,36 @@
   <string name="lock_button">锁定应用</string>
   <string name="settings_button">设置</string>
   <string name="sign_out_button">登出</string>
+  <string name="transports_onboarding_text">点击这里来控制Briar如何连接到您的联系人</string>
   <!--Transports: Tor-->
   <string name="transport_tor">互联网</string>
+  <string name="tor_device_status_online_wifi">你的手机通过Wi-Fi上网</string>
+  <string name="tor_device_status_online_mobile">您的手机通过移动数据访问互联网</string>
+  <string name="tor_device_status_offline">你的手机不能上网</string>
+  <string name="tor_plugin_status_enabling">Briar正在连接互联网</string>
+  <string name="tor_plugin_status_active">Briar 已联网</string>
+  <string name="tor_plugin_status_inactive">Briar 无法联网</string>
+  <string name="tor_plugin_status_disabled">Briar 配置为不使用互联网</string>
+  <string name="tor_plugin_status_disabled_mobile_data">Briar 配置为不使用移动数据</string>
+  <string name="tor_plugin_status_disabled_battery">Briar配置为在用电池运行时不使用互联网</string>
+  <string name="tor_plugin_status_disabled_country_blocked">Briar配置为在这个国家不使用互联网</string>
   <!--Transports: Wi-Fi-->
   <string name="transport_lan">无线局域网</string>
+  <string name="transport_lan_long">同一 Wi-Fi 网络</string>
+  <string name="lan_device_status_on">你的手机连接到Wi-Fi</string>
+  <string name="lan_device_status_off">你的手机未连接到Wi-Fi</string>
+  <string name="lan_plugin_status_enabling">Briar正在连接Wi-Fi网络</string>
+  <string name="lan_plugin_status_active">Briar已连接到此Wi-Fi网络</string>
+  <string name="lan_plugin_status_inactive">Briar不能连接到此Wi-Fi网络</string>
+  <string name="lan_plugin_status_disabled">Briar 配置为不使用Wi-Fi 网络</string>
   <!--Transports: Bluetooth-->
   <string name="transport_bt">蓝牙</string>
+  <string name="bt_device_status_on">你手机的蓝牙已打开</string>
+  <string name="bt_device_status_off">你手机额蓝牙已关闭</string>
+  <string name="bt_plugin_status_enabling">Briar 正连接蓝牙</string>
+  <string name="bt_plugin_status_active">Briar 已连接蓝牙</string>
+  <string name="bt_plugin_status_inactive">Briar 不能连接蓝牙</string>
+  <string name="bt_plugin_status_disabled">Briar 配置为不使用蓝牙</string>
   <!--Notifications-->
   <string name="reminder_notification_title">已登出 Briar</string>
   <string name="reminder_notification_text">轻按以重新登录。</string>
@@ -108,6 +132,7 @@
   <string name="help">帮助</string>
   <string name="sorry">抱歉</string>
   <string name="error_start_activity">在您的系统上不可用</string>
+  <string name="status_heading">状态：</string>
   <!--Contacts and Private Conversations-->
   <string name="no_contacts">尚无联系人可供显示</string>
   <string name="no_contacts_action">轻按 + 号即可添加联系人</string>
@@ -414,6 +439,7 @@
   <!--How and when Briar will connect to Tor: E.g. "Don't connect to the Internet (in China)" or "Use Tor network with bridges (in Belarus)"-->
   <string name="tor_network_setting_summary">自动选择：%1$s（在 %2$s）</string>
   <string name="tor_mobile_data_title">使用移动数据</string>
+  <string name="tor_only_when_charging_title">仅在充电时联网</string>
   <string name="tor_only_when_charging_summary">当设备使用电池电量时关闭网络连接</string>
   <!--Settings Security and Panic-->
   <string name="security_settings_title">安全</string>
@@ -524,6 +550,7 @@
   <string name="lock_is_locked">Briar 已锁定</string>
   <string name="lock_tap_to_unlock">轻按以解锁</string>
   <!--Connections Screen-->
+  <string name="transports_help_text">Briar可以通过互联网、Wi-Fi或蓝牙连接到您的联系人。\n\n为了保护隐私，所有的互联网连接都通过Tor网络。\n\n如果一个联系人可以通过多种方法联系到，Briar会并行地使用它们。</string>
   <!--Screenshots-->
   <!--This is a name to be used in screenshots. Feel free to change it to a local name.-->
   <string name="screenshot_alice">韩梅梅</string>

briar-android/src/main/res/values/strings.xml

@@ -210,7 +210,6 @@
 	<string name="connecting_to_device">Connecting to device\u2026</string>
 	<string name="authenticating_with_device">Authenticating with device\u2026</string>
 	<string name="connection_error_title">Could not connect to your contact</string>
-	<string name="connection_error_explanation">Please check that you\'re both connected to the same Wi-Fi network.</string>
 	<string name="connection_error_feedback">If this problem persists, please <a href="feedback">send feedback</a> to help us improve the app.</string>
 
 	<!-- Adding Contacts Remotely -->
@@ -589,6 +588,7 @@
 	<string name="permission_camera_location_title">Camera and location</string>
 	<string name="permission_camera_location_request_body">To scan the QR code, Briar needs access to the camera.\n\nTo discover Bluetooth devices, Briar needs permission to access your location.\n\nBriar does not store your location or share it with anyone.</string>
 	<string name="permission_camera_denied_body">You have denied access to the camera, but adding contacts requires using the camera.\n\nPlease consider granting access.</string>
+	<string name="permission_location_denied_body">You have denied access to your location, but Briar needs this permission to discover Bluetooth devices.\n\nPlease consider granting access.</string>
 	<string name="qr_code">QR code</string>
 	<string name="show_qr_code_fullscreen">Show QR code fullscreen</string>
 

briar-android/src/test/java/org/briarproject/briar/android/attachment/AttachmentRetrieverTest.java

@@ -2,6 +2,7 @@ package org.briarproject.briar.android.attachment;
 
 import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.bramble.test.BrambleMockTestCase;
+import org.briarproject.bramble.test.ImmediateExecutor;
 import org.briarproject.briar.api.messaging.Attachment;
 import org.briarproject.briar.api.messaging.AttachmentHeader;
 import org.briarproject.briar.api.messaging.MessagingManager;
@@ -11,12 +12,13 @@ import org.junit.Test;
 
 import java.io.ByteArrayInputStream;
 import java.io.InputStream;
+import java.util.concurrent.Executor;
 
 import static org.briarproject.bramble.test.TestUtils.getRandomBytes;
 import static org.briarproject.bramble.test.TestUtils.getRandomId;
+import static org.briarproject.briar.android.attachment.AttachmentItem.State.AVAILABLE;
+import static org.briarproject.briar.android.attachment.AttachmentItem.State.ERROR;
 import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertFalse;
-import static org.junit.Assert.assertTrue;
 
 public class AttachmentRetrieverTest extends BrambleMockTestCase {
 
@@ -33,8 +35,9 @@ public class AttachmentRetrieverTest extends BrambleMockTestCase {
 		MessagingManager messagingManager =
 				context.mock(MessagingManager.class);
 		imageSizeCalculator = context.mock(ImageSizeCalculator.class);
-		retriever = new AttachmentRetrieverImpl(messagingManager, dimensions,
-				imageHelper, imageSizeCalculator);
+		Executor dbExecutor = new ImmediateExecutor();
+		retriever = new AttachmentRetrieverImpl(dbExecutor, messagingManager,
+				dimensions, imageHelper, imageSizeCalculator);
 	}
 
 	@Test
@@ -47,10 +50,10 @@ public class AttachmentRetrieverTest extends BrambleMockTestCase {
 			will(returnValue("jpg"));
 		}});
 
-		AttachmentItem item = retriever.getAttachmentItem(attachment, false);
+		AttachmentItem item = retriever.createAttachmentItem(attachment, false);
 		assertEquals(mimeType, item.getMimeType());
 		assertEquals("jpg", item.getExtension());
-		assertFalse(item.hasError());
+		assertEquals(AVAILABLE, item.getState());
 	}
 
 	@Test
@@ -63,8 +66,8 @@ public class AttachmentRetrieverTest extends BrambleMockTestCase {
 			will(returnValue(null));
 		}});
 
-		AttachmentItem item = retriever.getAttachmentItem(attachment, false);
-		assertTrue(item.hasError());
+		AttachmentItem item = retriever.createAttachmentItem(attachment, false);
+		assertEquals(ERROR, item.getState());
 	}
 
 	@Test
@@ -80,7 +83,7 @@ public class AttachmentRetrieverTest extends BrambleMockTestCase {
 			will(returnValue("jpg"));
 		}});
 
-		AttachmentItem item = retriever.getAttachmentItem(attachment, true);
+		AttachmentItem item = retriever.createAttachmentItem(attachment, true);
 		assertEquals(msgId, item.getMessageId());
 		assertEquals(160, item.getWidth());
 		assertEquals(240, item.getHeight());
@@ -88,7 +91,7 @@ public class AttachmentRetrieverTest extends BrambleMockTestCase {
 		assertEquals(240, item.getThumbnailHeight());
 		assertEquals(mimeType, item.getMimeType());
 		assertEquals("jpg", item.getExtension());
-		assertFalse(item.hasError());
+		assertEquals(AVAILABLE, item.getState());
 	}
 
 	@Test
@@ -104,12 +107,12 @@ public class AttachmentRetrieverTest extends BrambleMockTestCase {
 			will(returnValue("jpg"));
 		}});
 
-		AttachmentItem item = retriever.getAttachmentItem(attachment, true);
+		AttachmentItem item = retriever.createAttachmentItem(attachment, true);
 		assertEquals(1728, item.getWidth());
 		assertEquals(2592, item.getHeight());
 		assertEquals(dimensions.maxWidth, item.getThumbnailWidth());
 		assertEquals(dimensions.maxHeight, item.getThumbnailHeight());
-		assertFalse(item.hasError());
+		assertEquals(AVAILABLE, item.getState());
 	}
 
 	@Test
@@ -125,8 +128,8 @@ public class AttachmentRetrieverTest extends BrambleMockTestCase {
 			will(returnValue(null));
 		}});
 
-		AttachmentItem item = retriever.getAttachmentItem(attachment, true);
-		assertTrue(item.hasError());
+		AttachmentItem item = retriever.createAttachmentItem(attachment, true);
+		assertEquals(ERROR, item.getState());
 	}
 
 	private Attachment getAttachment(String contentType) {

briar-api/src/main/java/org/briarproject/briar/api/messaging/MessagingManager.java

@@ -68,7 +68,7 @@ public interface MessagingManager extends ConversationClient {
 	String getMessageText(MessageId m) throws DbException;
 
 	/**
-	 * Returns the attachment with the given message ID and content type.
+	 * Returns the attachment with the given attachment header.
 	 *
 	 * @throws InvalidAttachmentException If the header refers to a message
 	 * that is not an attachment, or to an attachment that does not have the

briar-headless/README.md

@@ -69,7 +69,8 @@ Returns a JSON array of contacts:
     "handshakePublicKey": "XnYRd7a7E4CTqgAvh4hCxh/YZ0EPscxknB9ZcEOpSzY=",
     "verified": true,
     "lastChatActivity": 1557838312175,
-    "connected": false
+    "connected": false,
+    "unreadCount": 7
 }
 ```
 
@@ -182,6 +183,18 @@ Note that it's also possible to add contacts nearby via Bluetooth/Wifi or
 introductions. In these cases contacts omit the `pendingContact` state and
 directly become `contact`s.
 
+### Changing alias of a contact
+
+`PUT /v1/contacts/{contactId}/alias`
+
+The alias should be posted as a JSON object:
+
+```json
+{
+    "alias": "A nickname for the new contact"
+}
+```
+
 ### Removing a contact
 
 `DELETE /v1/contacts/{contactId}`
@@ -233,6 +246,25 @@ The text of the message should be posted as JSON:
 }
 ```
 
+### Marking private messages as read
+
+`POST /v1/messages/{contactId}/read`
+
+The `messageId` of the message to be marked as read
+needs to be provided in the request body as follows:
+
+```json
+{
+    "messageId": "+AIMMgOCPFF8HDEhiEHYjbfKrg7v0G94inKxjvjYzA8="
+}
+```
+
+### Deleting all private messages
+
+`DELETE /v1/messages/{contactId}/all`
+
+It returns with a status code `200`, if removal was successful.
+
 ### Listing blog posts
 
 `GET /v1/blogs/posts`
@@ -409,3 +441,39 @@ When the last connection is lost (the contact goes offline), it sends a `Contact
     "type": "event"
 }
 ```
+
+### A message was sent
+
+When Briar sent a message to a contact, it sends a `MessagesSentEvent`. This is indicated in Briar
+by showing one tick next to the message.
+
+```json
+{
+    "data": {
+        "contactId": 1,
+        "messageIds": [
+            "+AIMMgOCPFF8HDEhiEHYjbfKrg7v0G94inKxjvjYzA8="
+        ]
+    },
+    "name": "MessagesSentEvent",
+    "type": "event"
+}
+```
+
+### A message was acknowledged
+
+When a contact acknowledges that they received a message, Briar sends a `MessagesAckedEvent`.
+This is indicated in Briar by showing two ticks next to the message.
+
+```json
+{
+    "data": {
+        "contactId": 1,
+        "messageIds": [
+            "+AIMMgOCPFF8HDEhiEHYjbfKrg7v0G94inKxjvjYzA8="
+        ]
+    },
+    "name": "MessagesAckedEvent",
+    "type": "event"
+}
+```

briar-headless/src/main/java/org/briarproject/briar/headless/Router.kt

@@ -81,11 +81,20 @@ constructor(
                     path("/:contactId") {
                         delete { ctx -> contactController.delete(ctx) }
                     }
+                    path("/:contactId/alias") {
+                        put { ctx -> contactController.setContactAlias(ctx) }
+                    }
                 }
                 path("/messages/:contactId") {
                     get { ctx -> messagingController.list(ctx) }
                     post { ctx -> messagingController.write(ctx) }
                 }
+                path("/messages/:contactId/read") {
+                    post { ctx -> messagingController.markMessageRead(ctx) }
+                }
+                path("/messages/:contactId/all") {
+                    delete { ctx -> messagingController.deleteAllMessages(ctx) }
+                }
                 path("/forums") {
                     get { ctx -> forumController.list(ctx) }
                     post { ctx -> forumController.create(ctx) }

briar-headless/src/main/java/org/briarproject/briar/headless/contact/ContactController.kt

@@ -9,6 +9,7 @@ interface ContactController {
     fun addPendingContact(ctx: Context): Context
     fun listPendingContacts(ctx: Context): Context
     fun removePendingContact(ctx: Context): Context
+    fun setContactAlias(ctx: Context): Context
     fun delete(ctx: Context): Context
 
 }

briar-headless/src/main/java/org/briarproject/briar/headless/contact/ContactControllerImpl.kt

@@ -77,7 +77,8 @@ constructor(
         val contacts = contactManager.contacts.map { contact ->
             val latestMsgTime = conversationManager.getGroupCount(contact.id).latestMsgTime
             val connected = connectionRegistry.isConnected(contact.id)
-            contact.output(latestMsgTime, connected)
+            val unreadCount = conversationManager.getGroupCount(contact.id).unreadCount
+            contact.output(latestMsgTime, connected, unreadCount)
         }
         return ctx.json(contacts)
     }
@@ -91,9 +92,7 @@ constructor(
         val link = ctx.getFromJson(objectMapper, "link")
         val alias = ctx.getFromJson(objectMapper, "alias")
         if (!LINK_REGEX.matcher(link).find()) throw BadRequestResponse("Invalid Link")
-        val aliasUtf8 = toUtf8(alias)
-        if (aliasUtf8.isEmpty() || aliasUtf8.size > MAX_AUTHOR_NAME_LENGTH)
-            throw BadRequestResponse("Invalid Alias")
+        checkAliasLength(alias)
         val pendingContact = contactManager.addPendingContact(link, alias)
         return ctx.json(pendingContact.output())
     }
@@ -124,6 +123,18 @@ constructor(
         return ctx
     }
 
+    override fun setContactAlias(ctx: Context): Context {
+        val contactId = ctx.getContactIdFromPathParam()
+        val alias = ctx.getFromJson(objectMapper, "alias")
+        checkAliasLength(alias)
+        try {
+            contactManager.setContactAlias(contactId, alias)
+        } catch (e: NoSuchContactException) {
+            throw NotFoundResponse()
+        }
+        return ctx
+    }
+
     override fun delete(ctx: Context): Context {
         val contactId = ctx.getContactIdFromPathParam()
         try {
@@ -134,4 +145,10 @@ constructor(
         return ctx
     }
 
+    private fun checkAliasLength(alias: String) {
+        val aliasUtf8 = toUtf8(alias)
+        if (aliasUtf8.isEmpty() || aliasUtf8.size > MAX_AUTHOR_NAME_LENGTH)
+            throw BadRequestResponse("Invalid Alias")
+    }
+
 }

briar-headless/src/main/java/org/briarproject/briar/headless/contact/OutputContact.kt

@@ -7,12 +7,13 @@ import org.briarproject.bramble.api.plugin.event.ContactDisconnectedEvent
 import org.briarproject.bramble.identity.output
 import org.briarproject.briar.headless.json.JsonDict
 
-internal fun Contact.output(latestMsgTime: Long, connected: Boolean) = JsonDict(
+internal fun Contact.output(latestMsgTime: Long, connected: Boolean, unreadCount: Int) = JsonDict(
     "contactId" to id.int,
     "author" to author.output(),
     "verified" to isVerified,
     "lastChatActivity" to latestMsgTime,
-    "connected" to connected
+    "connected" to connected,
+    "unreadCount" to unreadCount
 ).apply {
     alias?.let { put("alias", it) }
     handshakePublicKey?.let { put("handshakePublicKey", it.encoded) }

briar-headless/src/main/java/org/briarproject/briar/headless/messaging/MessagingController.kt

@@ -8,4 +8,8 @@ interface MessagingController {
 
     fun write(ctx: Context): Context
 
+    fun markMessageRead(ctx: Context): Context
+
+    fun deleteAllMessages(ctx: Context): Context
+
 }

briar-headless/src/main/java/org/briarproject/briar/headless/messaging/MessagingControllerImpl.kt

@@ -11,6 +11,9 @@ import org.briarproject.bramble.api.db.DatabaseExecutor
 import org.briarproject.bramble.api.db.NoSuchContactException
 import org.briarproject.bramble.api.event.Event
 import org.briarproject.bramble.api.event.EventListener
+import org.briarproject.bramble.api.sync.event.MessagesAckedEvent
+import org.briarproject.bramble.api.sync.event.MessagesSentEvent
+import org.briarproject.bramble.api.sync.MessageId
 import org.briarproject.bramble.api.system.Clock
 import org.briarproject.bramble.util.StringUtils.utf8IsTooLong
 import org.briarproject.briar.api.blog.BlogInvitationRequest
@@ -33,12 +36,16 @@ import org.briarproject.briar.headless.event.output
 import org.briarproject.briar.headless.getContactIdFromPathParam
 import org.briarproject.briar.headless.getFromJson
 import org.briarproject.briar.headless.json.JsonDict
+import org.spongycastle.util.encoders.Base64
+import org.spongycastle.util.encoders.DecoderException
 import java.util.concurrent.Executor
 import javax.annotation.concurrent.Immutable
 import javax.inject.Inject
 import javax.inject.Singleton
 
 internal const val EVENT_CONVERSATION_MESSAGE = "ConversationMessageReceivedEvent"
+internal const val EVENT_MESSAGES_ACKED = "MessagesAckedEvent"
+internal const val EVENT_MESSAGES_SENT = "MessagesSentEvent"
 
 @Immutable
 @Singleton
@@ -79,6 +86,36 @@ constructor(
         return ctx.json(m.output(contact.id, text))
     }
 
+    override fun markMessageRead(ctx: Context): Context {
+        val contact = getContact(ctx)
+        val groupId = messagingManager.getContactGroup(contact).id
+
+        val messageIdString = ctx.getFromJson(objectMapper, "messageId")
+        val messageId = deserializeMessageId(messageIdString)
+        messagingManager.setReadFlag(groupId, messageId, true)
+        return ctx.json(messageIdString)
+    }
+
+    private fun deserializeMessageId(idString: String): MessageId {
+        val idBytes = try {
+            Base64.decode(idString)
+        } catch (e: DecoderException) {
+            throw NotFoundResponse()
+        }
+        if (idBytes.size != MessageId.LENGTH) throw NotFoundResponse()
+        return MessageId(idBytes)
+    }
+
+    override fun deleteAllMessages(ctx: Context): Context {
+        val contactId = ctx.getContactIdFromPathParam()
+        try {
+            val result = conversationManager.deleteAllMessages(contactId)
+            return ctx.json(result.output())
+        } catch (e: NoSuchContactException) {
+            throw NotFoundResponse()
+        }
+    }
+
     override fun eventOccurred(e: Event) {
         when (e) {
             is ConversationMessageReceivedEvent<*> -> {
@@ -90,6 +127,12 @@ constructor(
                     webSocketController.sendEvent(EVENT_CONVERSATION_MESSAGE, e.output())
                 }
             }
+            is MessagesSentEvent -> {
+                webSocketController.sendEvent(EVENT_MESSAGES_SENT, e.output())
+            }
+            is MessagesAckedEvent -> {
+                webSocketController.sendEvent(EVENT_MESSAGES_ACKED, e.output())
+            }
         }
     }
 

briar-headless/src/main/java/org/briarproject/briar/headless/messaging/OutputConversationMessage.kt

@@ -1,7 +1,11 @@
 package org.briarproject.briar.headless.messaging
 
 import org.briarproject.bramble.api.contact.ContactId
+import org.briarproject.bramble.api.sync.MessageId
+import org.briarproject.bramble.api.sync.event.MessagesAckedEvent
+import org.briarproject.bramble.api.sync.event.MessagesSentEvent
 import org.briarproject.briar.api.conversation.ConversationMessageHeader
+import org.briarproject.briar.api.conversation.DeletionResult
 import org.briarproject.briar.api.messaging.PrivateMessage
 import org.briarproject.briar.api.messaging.PrivateMessageHeader
 import org.briarproject.briar.headless.json.JsonDict
@@ -43,3 +47,24 @@ internal fun PrivateMessage.output(contactId: ContactId, text: String) = JsonDic
     "groupId" to message.groupId.bytes,
     "text" to text
 )
+
+internal fun DeletionResult.output() = JsonDict(
+    "allDeleted" to allDeleted(),
+    "hasIntroductionSessionInProgress" to hasIntroductionSessionInProgress(),
+    "hasInvitationSessionInProgress" to hasInvitationSessionInProgress(),
+    "hasNotAllIntroductionSelected" to hasNotAllIntroductionSelected(),
+    "hasNotAllInvitationSelected" to hasNotAllInvitationSelected(),
+    "hasNotFullyDownloaded" to hasNotFullyDownloaded()
+)
+
+internal fun MessagesAckedEvent.output() = JsonDict(
+    "contactId" to contactId.int,
+    "messageIds" to messageIds.toJson()
+)
+
+internal fun MessagesSentEvent.output() = JsonDict(
+    "contactId" to contactId.int,
+    "messageIds" to messageIds.toJson()
+)
+
+internal fun Collection<MessageId>.toJson() = map { it.bytes }

briar-headless/src/test/java/org/briarproject/briar/headless/ControllerTest.kt

@@ -46,6 +46,7 @@ abstract class ControllerTest {
     protected val message: Message = getMessage(group.id)
     protected val text: String = getRandomString(5)
     protected val timestamp = 42L
+    protected val unreadCount = 42
 
     protected fun assertJsonEquals(json: String, obj: Any) {
         assertEquals(json, outputCtx.json(obj).resultString(), STRICT)

briar-headless/src/test/java/org/briarproject/briar/headless/contact/ContactControllerTest.kt

@@ -6,6 +6,7 @@ import io.javalin.plugin.json.JavalinJson.toJson
 import io.mockk.Runs
 import io.mockk.every
 import io.mockk.just
+import io.mockk.mockkStatic
 import io.mockk.runs
 import org.briarproject.bramble.api.Pair
 import org.briarproject.bramble.api.contact.Contact
@@ -27,6 +28,7 @@ import org.briarproject.bramble.test.TestUtils.getPendingContact
 import org.briarproject.bramble.test.TestUtils.getRandomBytes
 import org.briarproject.bramble.util.StringUtils.getRandomString
 import org.briarproject.briar.headless.ControllerTest
+import org.briarproject.briar.headless.getFromJson
 import org.briarproject.briar.headless.json.JsonDict
 import org.junit.jupiter.api.Assertions.assertNotNull
 import org.junit.jupiter.api.Assertions.assertThrows
@@ -58,7 +60,8 @@ internal class ContactControllerTest : ControllerTest() {
         every { contactManager.contacts } returns listOf(contact)
         every { conversationManager.getGroupCount(contact.id).latestMsgTime } returns timestamp
         every { connectionRegistry.isConnected(contact.id) } returns connected
-        every { ctx.json(listOf(contact.output(timestamp, connected))) } returns ctx
+        every { conversationManager.getGroupCount(contact.id).unreadCount } returns unreadCount
+        every { ctx.json(listOf(contact.output(timestamp, connected, unreadCount))) } returns ctx
         controller.list(ctx)
     }
 
@@ -193,6 +196,66 @@ internal class ContactControllerTest : ControllerTest() {
         }
     }
 
+    @Test
+    fun testSetContactAlias() {
+        mockkStatic("org.briarproject.briar.headless.RouterKt")
+        every { ctx.pathParam("contactId") } returns "1"
+        every { ctx.getFromJson(objectMapper, "alias") } returns "foo"
+        every { contactManager.setContactAlias(ContactId(1), "foo") } just Runs
+        controller.setContactAlias(ctx)
+    }
+
+    @Test
+    fun testSetContactAliasInvalidId() {
+        mockkStatic("org.briarproject.briar.headless.RouterKt")
+        every { ctx.pathParam("contactId") } returns "foo"
+        every { ctx.getFromJson(objectMapper, "alias") } returns "bar"
+        assertThrows(NotFoundResponse::class.java) {
+            controller.setContactAlias(ctx)
+        }
+    }
+
+    @Test
+    fun testSetContactAliasNonexistentId() {
+        mockkStatic("org.briarproject.briar.headless.RouterKt")
+        every { ctx.pathParam("contactId") } returns "1"
+        every { ctx.getFromJson(objectMapper, "alias") } returns "foo"
+        every { contactManager.setContactAlias(ContactId(1), "foo") } throws NotFoundResponse()
+        assertThrows(NotFoundResponse::class.java) {
+            controller.setContactAlias(ctx)
+        }
+    }
+
+    @Test
+    fun testSetContactAliasInvalid() {
+        mockkStatic("org.briarproject.briar.headless.RouterKt")
+        every { ctx.pathParam("contactId") } returns "1"
+        every { ctx.getFromJson(objectMapper, "alias") } returns getRandomString(MAX_AUTHOR_NAME_LENGTH + 1)
+        assertThrows(BadRequestResponse::class.java) {
+            controller.setContactAlias(ctx)
+        }
+    }
+
+    @Test
+    fun testSetContactAliasEmpty() {
+        mockkStatic("org.briarproject.briar.headless.RouterKt")
+        every { ctx.pathParam("contactId") } returns "1"
+        every { ctx.getFromJson(objectMapper, "alias") } returns ""
+        assertThrows(BadRequestResponse::class.java) {
+            controller.setContactAlias(ctx)
+        }
+    }
+
+    @Test
+    fun testSetContactAliasMissing() {
+        mockkStatic("org.briarproject.briar.headless.RouterKt")
+        every { ctx.pathParam("contactId") } returns "1"
+        every { ctx.body() } returns ""
+        assertThrows(BadRequestResponse::class.java) {
+            controller.setContactAlias(ctx)
+        }
+    }
+
     @Test
     fun testDelete() {
         every { ctx.pathParam("contactId") } returns "1"
@@ -313,10 +376,11 @@ internal class ContactControllerTest : ControllerTest() {
                 "handshakePublicKey": ${toJson(contact.handshakePublicKey!!.encoded)},
                 "verified": ${contact.isVerified},
                 "lastChatActivity": $timestamp,
-                "connected": $connected
+                "connected": $connected,
+                "unreadCount": $unreadCount
             }
         """
-        assertJsonEquals(json, contact.output(timestamp, connected))
+        assertJsonEquals(json, contact.output(timestamp, connected, unreadCount))
     }
 
     @Test

briar-headless/src/test/java/org/briarproject/briar/headless/messaging/MessagingControllerImplTest.kt

@@ -10,11 +10,14 @@ import org.briarproject.bramble.api.db.NoSuchContactException
 import org.briarproject.bramble.api.identity.AuthorInfo
 import org.briarproject.bramble.api.identity.AuthorInfo.Status.UNVERIFIED
 import org.briarproject.bramble.api.identity.AuthorInfo.Status.VERIFIED
+import org.briarproject.bramble.api.sync.MessageId
+import org.briarproject.bramble.api.sync.event.MessagesAckedEvent
+import org.briarproject.bramble.api.sync.event.MessagesSentEvent
 import org.briarproject.bramble.test.ImmediateExecutor
 import org.briarproject.bramble.test.TestUtils.getRandomId
 import org.briarproject.bramble.util.StringUtils.getRandomString
 import org.briarproject.briar.api.client.SessionId
-import org.briarproject.briar.api.conversation.ConversationManager
+import org.briarproject.briar.api.conversation.DeletionResult
 import org.briarproject.briar.api.introduction.IntroductionRequest
 import org.briarproject.briar.api.messaging.MessagingConstants.MAX_PRIVATE_MESSAGE_TEXT_LENGTH
 import org.briarproject.briar.api.messaging.MessagingManager
@@ -24,10 +27,13 @@ import org.briarproject.briar.api.messaging.PrivateMessageHeader
 import org.briarproject.briar.api.messaging.event.PrivateMessageReceivedEvent
 import org.briarproject.briar.headless.ControllerTest
 import org.briarproject.briar.headless.event.output
+import org.briarproject.briar.headless.getFromJson
 import org.briarproject.briar.headless.json.JsonDict
 import org.junit.jupiter.api.Assertions.assertEquals
 import org.junit.jupiter.api.Assertions.assertThrows
 import org.junit.jupiter.api.Test
+import org.spongycastle.util.encoders.Base64
+import kotlin.random.Random
 
 internal class MessagingControllerImplTest : ControllerTest() {
 
@@ -100,6 +106,40 @@ internal class MessagingControllerImplTest : ControllerTest() {
         testInvalidContactId { controller.list(ctx) }
     }
 
+    @Test
+    fun testMessagesAckedEvent() {
+        val messageId1 = MessageId(getRandomId())
+        val messageId2 = MessageId(getRandomId())
+        val messageIds = listOf(messageId1, messageId2)
+        val event = MessagesAckedEvent(contact.id, messageIds)
+
+        every {
+            webSocketController.sendEvent(
+                EVENT_MESSAGES_ACKED,
+                event.output()
+            )
+        } just runs
+
+        controller.eventOccurred(event)
+    }
+
+    @Test
+    fun testMessagesSentEvent() {
+        val messageId1 = MessageId(getRandomId())
+        val messageId2 = MessageId(getRandomId())
+        val messageIds = listOf(messageId1, messageId2)
+        val event = MessagesSentEvent(contact.id, messageIds)
+
+        every {
+            webSocketController.sendEvent(
+                EVENT_MESSAGES_SENT,
+                event.output()
+            )
+        } just runs
+
+        controller.eventOccurred(event)
+    }
+
     @Test
     fun listNonexistentContactId() {
         testNonexistentContactId { controller.list(ctx) }
@@ -162,6 +202,32 @@ internal class MessagingControllerImplTest : ControllerTest() {
         assertThrows(BadRequestResponse::class.java) { controller.write(ctx) }
     }
 
+    @Test
+    fun markMessageRead() {
+        mockkStatic("org.briarproject.briar.headless.RouterKt")
+        mockkStatic("org.spongycastle.util.encoders.Base64")
+        expectGetContact()
+
+        val messageIdString = message.id.bytes.toString()
+        every { messagingManager.getContactGroup(contact).id } returns group.id
+        every { ctx.getFromJson(objectMapper, "messageId") } returns messageIdString
+        every { Base64.decode(messageIdString) } returns message.id.bytes
+        every { messagingManager.setReadFlag(group.id, message.id, true) } just Runs
+        every { ctx.json(messageIdString) } returns ctx
+
+        controller.markMessageRead(ctx)
+    }
+
+    @Test
+    fun markMessageReadInvalidContactId() {
+        testInvalidContactId { controller.markMessageRead(ctx) }
+    }
+
+    @Test
+    fun markMessageReadNonexistentId() {
+        testNonexistentContactId { controller.markMessageRead(ctx) }
+    }
+
     @Test
     fun privateMessageEvent() {
         val event = PrivateMessageReceivedEvent(header, contact.id)
@@ -177,6 +243,43 @@ internal class MessagingControllerImplTest : ControllerTest() {
         controller.eventOccurred(event)
     }
 
+    @Test
+    fun testOutputMessagesAckedEvent() {
+        val messageId1 = MessageId(getRandomId())
+        val messageId2 = MessageId(getRandomId())
+        val messageIds = listOf(messageId1, messageId2)
+        val event = MessagesAckedEvent(contact.id, messageIds)
+        val json = """
+            {
+                "contactId": ${contact.id.int},
+                "messageIds": [
+                    ${toJson(messageId1.bytes)},
+                    ${toJson(messageId2.bytes)}
+                ]
+            }
+        """
+        assertJsonEquals(json, event.output())
+    }
+
+    @Test
+    fun testOutputMessagesSentEvent() {
+        val messageId1 = MessageId(getRandomId())
+        val messageId2 = MessageId(getRandomId())
+        val messageIds = listOf(messageId1, messageId2)
+        val event = MessagesSentEvent(contact.id, messageIds)
+
+        val json = """
+            {
+                "contactId": ${contact.id.int},
+                "messageIds": [
+                    ${toJson(messageId1.bytes)},
+                    ${toJson(messageId2.bytes)}
+                ]
+            }
+        """
+        assertJsonEquals(json, event.output())
+    }
+
     @Test
     fun testOutputPrivateMessageHeader() {
         val json = """
@@ -242,6 +345,53 @@ internal class MessagingControllerImplTest : ControllerTest() {
         assertJsonEquals(json, request.output(contact.id))
     }
 
+    @Test
+    fun testDeleteAllMessages() {
+        val result = DeletionResult()
+        every { ctx.pathParam("contactId") } returns "1"
+        every { conversationManager.deleteAllMessages(ContactId(1)) } returns result
+        every { ctx.json(result.output()) } returns ctx
+        controller.deleteAllMessages(ctx)
+    }
+
+    @Test
+    fun testDeleteAllMessagesInvalidContactId() {
+        every { ctx.pathParam("contactId") } returns "foo"
+        assertThrows(NotFoundResponse::class.java) {
+            controller.deleteAllMessages(ctx)
+        }
+    }
+
+    @Test
+    fun testDeleteAllMessagesNonexistentContactId() {
+        every { ctx.pathParam("contactId") } returns "1"
+        every { conversationManager.deleteAllMessages(ContactId(1)) } throws NoSuchContactException()
+        assertThrows(NotFoundResponse::class.java) {
+            controller.deleteAllMessages(ctx)
+        }
+    }
+
+    @Test
+    fun testOutputDeletionResult() {
+        val result = DeletionResult()
+        if (Random.nextBoolean()) result.addInvitationNotAllSelected()
+        if (Random.nextBoolean()) result.addInvitationSessionInProgress()
+        if (Random.nextBoolean()) result.addIntroductionNotAllSelected()
+        if (Random.nextBoolean()) result.addIntroductionSessionInProgress()
+        if (Random.nextBoolean()) result.addNotFullyDownloaded()
+        val json = """
+            {
+                "allDeleted": ${result.allDeleted()},
+                "hasIntroductionSessionInProgress": ${result.hasIntroductionSessionInProgress()},
+                "hasInvitationSessionInProgress": ${result.hasInvitationSessionInProgress()},
+                "hasNotAllIntroductionSelected": ${result.hasNotAllIntroductionSelected()},
+                "hasNotAllInvitationSelected": ${result.hasNotAllInvitationSelected()},
+                "hasNotFullyDownloaded": ${result.hasNotFullyDownloaded()}
+            }
+        """
+        assertJsonEquals(json, result.output())
+    }
+
     private fun expectGetContact() {
         every { ctx.pathParam("contactId") } returns contact.id.int.toString()
         every { contactManager.getContact(contact.id) } returns contact

build.gradle

@@ -33,3 +33,12 @@ buildscript {
 		classpath files('libs/gradle-witness.jar')
 	}
 }
+
+project.ext {
+	buildToolsVersion = '30.0.2'
+	compileSdkVersion = 30
+	minSdkVersion = 16
+	targetSdkVersion = 29
+	versionCode = 10211
+	versionName = '1.2.11'
+}