Bump version numbers for 1.2.13 release.

Do not produce malformed links for adding contacts when on other locales such as Turkish

Closes #1885

See merge request briar/briar!1335

.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>

.idea/runConfigurations/All_tests.xml

@@ -1,6 +1,6 @@
 <component name="ProjectRunConfigurationManager">
   <configuration default="false" name="All tests" type="AndroidJUnit" factoryName="Android JUnit">
-    <module name="briar-android" />
+    <module name="briar.briar-android" />
     <option name="PACKAGE_NAME" value="" />
     <option name="MAIN_CLASS_NAME" value="" />
     <option name="METHOD_NAME" value="" />

.idea/runConfigurations/All_tests_in_bramble_android.xml

@@ -1,20 +1,14 @@
 <component name="ProjectRunConfigurationManager">
   <configuration default="false" name="All tests in bramble-android" type="AndroidJUnit" factoryName="Android JUnit">
-    <module name="bramble-android" />
+    <module name="briar.bramble-android" />
-    <option name="ALTERNATIVE_JRE_PATH_ENABLED" value="false" />
-    <option name="ALTERNATIVE_JRE_PATH" />
     <option name="PACKAGE_NAME" value="" />
     <option name="MAIN_CLASS_NAME" value="" />
     <option name="METHOD_NAME" value="" />
     <option name="TEST_OBJECT" value="package" />
-    <option name="VM_PARAMETERS" value="-ea" />
     <option name="PARAMETERS" value="" />
     <option name="WORKING_DIRECTORY" value="file://$PROJECT_DIR$/bramble-android" />
-    <option name="PASS_PARENT_ENVS" value="true" />
+    <method v="2">
-    <option name="TEST_SEARCH_SCOPE">
+      <option name="Android.Gradle.BeforeRunTask" enabled="true" />
-      <value defaultName="singleModule" />
+    </method>
-    </option>
-    <patterns />
-    <method />
   </configuration>
 </component>

.idea/runConfigurations/All_tests_in_bramble_api.xml

@@ -1,20 +1,14 @@
 <component name="ProjectRunConfigurationManager">
   <configuration default="false" name="All tests in bramble-api" type="AndroidJUnit" factoryName="Android JUnit">
-    <module name="bramble-api" />
+    <module name="briar.bramble-api" />
-    <option name="ALTERNATIVE_JRE_PATH_ENABLED" value="false" />
-    <option name="ALTERNATIVE_JRE_PATH" />
     <option name="PACKAGE_NAME" value="" />
     <option name="MAIN_CLASS_NAME" value="" />
     <option name="METHOD_NAME" value="" />
     <option name="TEST_OBJECT" value="package" />
-    <option name="VM_PARAMETERS" value="-ea" />
     <option name="PARAMETERS" value="" />
     <option name="WORKING_DIRECTORY" value="file://$PROJECT_DIR$/bramble-api" />
-    <option name="PASS_PARENT_ENVS" value="true" />
+    <method v="2">
-    <option name="TEST_SEARCH_SCOPE">
+      <option name="Android.Gradle.BeforeRunTask" enabled="true" />
-      <value defaultName="singleModule" />
+    </method>
-    </option>
-    <patterns />
-    <method />
   </configuration>
 </component>

.idea/runConfigurations/All_tests_in_bramble_core.xml

@@ -1,20 +1,14 @@
 <component name="ProjectRunConfigurationManager">
   <configuration default="false" name="All tests in bramble-core" type="AndroidJUnit" factoryName="Android JUnit">
-    <module name="bramble-core" />
+    <module name="briar.bramble-core" />
-    <option name="ALTERNATIVE_JRE_PATH_ENABLED" value="false" />
-    <option name="ALTERNATIVE_JRE_PATH" />
     <option name="PACKAGE_NAME" value="" />
     <option name="MAIN_CLASS_NAME" value="" />
     <option name="METHOD_NAME" value="" />
     <option name="TEST_OBJECT" value="package" />
-    <option name="VM_PARAMETERS" value="-ea" />
     <option name="PARAMETERS" value="" />
     <option name="WORKING_DIRECTORY" value="file://$PROJECT_DIR$/bramble-core" />
-    <option name="PASS_PARENT_ENVS" value="true" />
+    <method v="2">
-    <option name="TEST_SEARCH_SCOPE">
+      <option name="Android.Gradle.BeforeRunTask" enabled="true" />
-      <value defaultName="singleModule" />
+    </method>
-    </option>
-    <patterns />
-    <method />
   </configuration>
 </component>

.idea/runConfigurations/All_tests_in_bramble_java.xml

@@ -1,8 +1,6 @@
 <component name="ProjectRunConfigurationManager">
   <configuration default="false" name="All tests in bramble-java" type="AndroidJUnit" factoryName="Android JUnit">
-    <module name="bramble-java" />
+    <module name="briar.bramble-java" />
-    <option name="ALTERNATIVE_JRE_PATH_ENABLED" value="false" />
-    <option name="ALTERNATIVE_JRE_PATH" />
     <option name="PACKAGE_NAME" value="" />
     <option name="MAIN_CLASS_NAME" value="" />
     <option name="METHOD_NAME" value="" />
@@ -10,11 +8,8 @@
     <option name="VM_PARAMETERS" value="-ea -Djava.library.path=libs" />
     <option name="PARAMETERS" value="" />
     <option name="WORKING_DIRECTORY" value="file://$PROJECT_DIR$/bramble-java" />
-    <option name="PASS_PARENT_ENVS" value="true" />
+    <method v="2">
-    <option name="TEST_SEARCH_SCOPE">
+      <option name="Android.Gradle.BeforeRunTask" enabled="true" />
-      <value defaultName="singleModule" />
+    </method>
-    </option>
-    <patterns />
-    <method />
   </configuration>
 </component>

.idea/runConfigurations/All_tests_in_briar_android.xml

@@ -1,20 +1,14 @@
 <component name="ProjectRunConfigurationManager">
   <configuration default="false" name="All tests in briar-android" type="AndroidJUnit" factoryName="Android JUnit">
-    <module name="briar-android" />
+    <module name="briar.briar-android" />
-    <option name="ALTERNATIVE_JRE_PATH_ENABLED" value="false" />
-    <option name="ALTERNATIVE_JRE_PATH" />
     <option name="PACKAGE_NAME" value="" />
     <option name="MAIN_CLASS_NAME" value="" />
     <option name="METHOD_NAME" value="" />
     <option name="TEST_OBJECT" value="package" />
-    <option name="VM_PARAMETERS" value="-ea" />
     <option name="PARAMETERS" value="" />
     <option name="WORKING_DIRECTORY" value="file://$PROJECT_DIR$/briar-android" />
-    <option name="PASS_PARENT_ENVS" value="true" />
+    <method v="2">
-    <option name="TEST_SEARCH_SCOPE">
+      <option name="Android.Gradle.BeforeRunTask" enabled="true" />
-      <value defaultName="singleModule" />
+    </method>
-    </option>
-    <patterns />
-    <method />
   </configuration>
 </component>

.idea/runConfigurations/All_tests_in_briar_core.xml

@@ -1,20 +1,14 @@
 <component name="ProjectRunConfigurationManager">
   <configuration default="false" name="All tests in briar-core" type="AndroidJUnit" factoryName="Android JUnit">
-    <module name="briar-core" />
+    <module name="briar.briar-core" />
-    <option name="ALTERNATIVE_JRE_PATH_ENABLED" value="false" />
-    <option name="ALTERNATIVE_JRE_PATH" />
     <option name="PACKAGE_NAME" value="" />
     <option name="MAIN_CLASS_NAME" value="" />
     <option name="METHOD_NAME" value="" />
     <option name="TEST_OBJECT" value="package" />
-    <option name="VM_PARAMETERS" value="-ea" />
     <option name="PARAMETERS" value="" />
     <option name="WORKING_DIRECTORY" value="file://$PROJECT_DIR$/briar-core" />
-    <option name="PASS_PARENT_ENVS" value="true" />
+    <method v="2">
-    <option name="TEST_SEARCH_SCOPE">
+      <option name="Android.Gradle.BeforeRunTask" enabled="true" />
-      <value defaultName="singleModule" />
+    </method>
-    </option>
-    <patterns />
-    <method />
   </configuration>
 </component>

.idea/runConfigurations/All_tests_in_briar_headless.xml

@@ -1,6 +1,6 @@
 <component name="ProjectRunConfigurationManager">
   <configuration default="false" name="All tests in briar-headless" type="AndroidJUnit" factoryName="Android JUnit">
-    <module name="briar-headless" />
+    <module name="briar.briar-headless" />
     <option name="PACKAGE_NAME" value="org.briarproject.briar.headless" />
     <option name="MAIN_CLASS_NAME" value="" />
     <option name="METHOD_NAME" value="" />

.idea/runConfigurations/H2_Performance_Test.xml

@@ -1,20 +1,14 @@
 <component name="ProjectRunConfigurationManager">
   <configuration default="false" name="H2 Performance Test" type="AndroidJUnit" factoryName="Android JUnit">
-    <module name="bramble-core" />
+    <module name="briar.bramble-core" />
-    <option name="ALTERNATIVE_JRE_PATH_ENABLED" value="false" />
-    <option name="ALTERNATIVE_JRE_PATH" />
     <option name="PACKAGE_NAME" value="org.briarproject.bramble.db" />
     <option name="MAIN_CLASS_NAME" value="org.briarproject.bramble.db.H2DatabasePerformanceTest" />
     <option name="METHOD_NAME" value="" />
     <option name="TEST_OBJECT" value="class" />
-    <option name="VM_PARAMETERS" value="-ea" />
     <option name="PARAMETERS" value="" />
     <option name="WORKING_DIRECTORY" value="" />
-    <option name="PASS_PARENT_ENVS" value="true" />
+    <method v="2">
-    <option name="TEST_SEARCH_SCOPE">
+      <option name="Android.Gradle.BeforeRunTask" enabled="true" />
-      <value defaultName="singleModule" />
+    </method>
-    </option>
-    <patterns />
-    <method />
   </configuration>
 </component>

.idea/runConfigurations/HyperSQL_Performance_Test.xml

@@ -1,20 +1,14 @@
 <component name="ProjectRunConfigurationManager">
   <configuration default="false" name="HyperSQL Performance Test" type="AndroidJUnit" factoryName="Android JUnit">
-    <module name="bramble-core" />
+    <module name="briar.bramble-core" />
-    <option name="ALTERNATIVE_JRE_PATH_ENABLED" value="false" />
-    <option name="ALTERNATIVE_JRE_PATH" />
     <option name="PACKAGE_NAME" value="org.briarproject.bramble.db" />
     <option name="MAIN_CLASS_NAME" value="org.briarproject.bramble.db.HyperSqlDatabasePerformanceTest" />
     <option name="METHOD_NAME" value="" />
     <option name="TEST_OBJECT" value="class" />
-    <option name="VM_PARAMETERS" value="-ea" />
     <option name="PARAMETERS" value="" />
     <option name="WORKING_DIRECTORY" value="" />
-    <option name="PASS_PARENT_ENVS" value="true" />
+    <method v="2">
-    <option name="TEST_SEARCH_SCOPE">
+      <option name="Android.Gradle.BeforeRunTask" enabled="true" />
-      <value defaultName="singleModule" />
+    </method>
-    </option>
-    <patterns />
-    <method />
   </configuration>
 </component>

.idea/runConfigurations/briar_headless.xml

@@ -1,6 +1,6 @@
 <component name="ProjectRunConfigurationManager">
-  <configuration default="false" name="briar-headless" type="JetRunConfigurationType" factoryName="Kotlin" singleton="true">
+  <configuration default="false" name="briar-headless" type="JetRunConfigurationType" singleton="true">
-    <extension name="coverage" enabled="false" merge="false" sample_coverage="true" runner="idea" />
+    <module name="briar.briar-headless" />
     <option name="VM_PARAMETERS" value="" />
     <option name="PROGRAM_PARAMETERS" value="-v" />
     <option name="ALTERNATIVE_JRE_PATH_ENABLED" value="false" />
@@ -8,9 +8,8 @@
     <option name="PASS_PARENT_ENVS" value="true" />
     <option name="MAIN_CLASS_NAME" value="org.briarproject.briar.headless.MainKt" />
     <option name="WORKING_DIRECTORY" value="" />
-    <module name="briar-headless" />
+    <method v="2">
-    <envs />
+      <option name="Make" enabled="true" />
-    <method>
       <option name="Gradle.BeforeRunTask" enabled="true" tasks="jar" externalProjectPath="$PROJECT_DIR$/briar-headless" vmOptions="" scriptParameters="" />
     </method>
   </configuration>

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
+	compileSdkVersion rootProject.ext.compileSdkVersion
-	buildToolsVersion '29.0.2'
+	buildToolsVersion rootProject.ext.buildToolsVersion
 
 	defaultConfig {
-		minSdkVersion 16
+		minSdkVersion rootProject.ext.minSdkVersion
-		targetSdkVersion 28
+		targetSdkVersion rootProject.ext.targetSdkVersion
-		versionCode 10209
+		versionCode rootProject.ext.versionCode
-		versionName "1.2.9"
+		versionName rootProject.ext.versionName
 		consumerProguardFiles 'proguard-rules.txt'
 
 		testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
@@ -38,7 +38,7 @@ configurations {
 
 dependencies {
 	implementation project(path: ':bramble-core', configuration: 'default')
-	tor 'org.briarproject:tor-android:0.3.5.10@zip'
+	tor 'org.briarproject:tor-android:0.3.5.12@zip'
 	tor 'org.briarproject:obfs4proxy-android:0.0.11-2@zip'
 
 	annotationProcessor 'com.google.dagger:dagger-compiler:2.24'
@@ -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'
-			include 'geoip.zip', '*_pie.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/network/AndroidNetworkManager.java

@@ -1,11 +1,15 @@
 package org.briarproject.bramble.network;
 
+import android.annotation.TargetApi;
 import android.app.Application;
 import android.content.BroadcastReceiver;
 import android.content.Context;
 import android.content.Intent;
 import android.content.IntentFilter;
 import android.net.ConnectivityManager;
+import android.net.LinkAddress;
+import android.net.LinkProperties;
+import android.net.Network;
 import android.net.NetworkInfo;
 
 import org.briarproject.bramble.api.event.EventBus;
@@ -19,6 +23,11 @@ import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.bramble.api.system.TaskScheduler;
 import org.briarproject.bramble.api.system.TaskScheduler.Cancellable;
 
+import java.net.Inet4Address;
+import java.net.InetAddress;
+import java.net.NetworkInterface;
+import java.net.SocketException;
+import java.util.Enumeration;
 import java.util.concurrent.Executor;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicBoolean;
@@ -36,16 +45,22 @@ import static android.net.ConnectivityManager.TYPE_WIFI;
 import static android.net.wifi.p2p.WifiP2pManager.WIFI_P2P_THIS_DEVICE_CHANGED_ACTION;
 import static android.os.Build.VERSION.SDK_INT;
 import static android.os.PowerManager.ACTION_DEVICE_IDLE_MODE_CHANGED;
+import static java.net.NetworkInterface.getNetworkInterfaces;
+import static java.util.Collections.list;
 import static java.util.concurrent.TimeUnit.MINUTES;
 import static java.util.concurrent.TimeUnit.SECONDS;
 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.nullsafety.NullSafety.requireNonNull;
+import static org.briarproject.bramble.util.LogUtils.logException;
 
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
 class AndroidNetworkManager implements NetworkManager, Service {
 
 	private static final Logger LOG =
-			Logger.getLogger(AndroidNetworkManager.class.getName());
+			getLogger(AndroidNetworkManager.class.getName());
 
 	// See android.net.wifi.WifiManager
 	private static final String WIFI_AP_STATE_CHANGED_ACTION =
@@ -54,7 +69,8 @@ class AndroidNetworkManager implements NetworkManager, Service {
 	private final TaskScheduler scheduler;
 	private final EventBus eventBus;
 	private final Executor eventExecutor;
-	private final Context appContext;
+	private final Application app;
+	private final ConnectivityManager connectivityManager;
 	private final AtomicReference<Cancellable> connectivityCheck =
 			new AtomicReference<>();
 	private final AtomicBoolean used = new AtomicBoolean(false);
@@ -67,7 +83,9 @@ class AndroidNetworkManager implements NetworkManager, Service {
 		this.scheduler = scheduler;
 		this.eventBus = eventBus;
 		this.eventExecutor = eventExecutor;
-		this.appContext = app.getApplicationContext();
+		this.app = app;
+		connectivityManager = (ConnectivityManager)
+				requireNonNull(app.getSystemService(CONNECTIVITY_SERVICE));
 	}
 
 	@Override
@@ -82,24 +100,82 @@ class AndroidNetworkManager implements NetworkManager, Service {
 		filter.addAction(WIFI_AP_STATE_CHANGED_ACTION);
 		filter.addAction(WIFI_P2P_THIS_DEVICE_CHANGED_ACTION);
 		if (SDK_INT >= 23) filter.addAction(ACTION_DEVICE_IDLE_MODE_CHANGED);
-		appContext.registerReceiver(networkStateReceiver, filter);
+		app.registerReceiver(networkStateReceiver, filter);
 	}
 
 	@Override
 	public void stopService() {
 		if (networkStateReceiver != null)
-			appContext.unregisterReceiver(networkStateReceiver);
+			app.unregisterReceiver(networkStateReceiver);
 	}
 
 	@Override
 	public NetworkStatus getNetworkStatus() {
-		ConnectivityManager cm = (ConnectivityManager)
+		NetworkInfo net = connectivityManager.getActiveNetworkInfo();
-				appContext.getSystemService(CONNECTIVITY_SERVICE);
-		if (cm == null) throw new AssertionError();
-		NetworkInfo net = cm.getActiveNetworkInfo();
 		boolean connected = net != null && net.isConnected();
-		boolean wifi = connected && net.getType() == TYPE_WIFI;
+		boolean wifi = false, ipv6Only = false;
-		return new NetworkStatus(connected, wifi);
+		if (connected) {
+			wifi = net.getType() == TYPE_WIFI;
+			if (SDK_INT >= 23) ipv6Only = isActiveNetworkIpv6Only();
+			else ipv6Only = areAllAvailableNetworksIpv6Only();
+		}
+		return new NetworkStatus(connected, wifi, ipv6Only);
+	}
+
+	/**
+	 * Returns true if the
+	 * {@link ConnectivityManager#getActiveNetwork() active network} has an
+	 * IPv6 unicast address and no IPv4 addresses. The active network is
+	 * assumed not to be a loopback interface.
+	 */
+	@TargetApi(23)
+	private boolean isActiveNetworkIpv6Only() {
+		Network net = connectivityManager.getActiveNetwork();
+		if (net == null) {
+			LOG.info("No active network");
+			return false;
+		}
+		LinkProperties props = connectivityManager.getLinkProperties(net);
+		if (props == null) {
+			LOG.info("No link properties for active network");
+			return false;
+		}
+		boolean hasIpv6Unicast = false;
+		for (LinkAddress linkAddress : props.getLinkAddresses()) {
+			InetAddress addr = linkAddress.getAddress();
+			if (addr instanceof Inet4Address) return false;
+			if (!addr.isMulticastAddress()) hasIpv6Unicast = true;
+		}
+		return hasIpv6Unicast;
+	}
+
+	/**
+	 * Returns true if the device has at least one network interface with an
+	 * IPv6 unicast address and no interfaces with IPv4 addresses, excluding
+	 * loopback interfaces and interfaces that are
+	 * {@link NetworkInterface#isUp() down}. If this method returns true and
+	 * the device has internet access then it's via IPv6 only.
+	 */
+	private boolean areAllAvailableNetworksIpv6Only() {
+		try {
+			Enumeration<NetworkInterface> interfaces = getNetworkInterfaces();
+			if (interfaces == null) {
+				LOG.info("No network interfaces");
+				return false;
+			}
+			boolean hasIpv6Unicast = false;
+			for (NetworkInterface i : list(interfaces)) {
+				if (i.isLoopback() || !i.isUp()) continue;
+				for (InetAddress addr : list(i.getInetAddresses())) {
+					if (addr instanceof Inet4Address) return false;
+					if (!addr.isMulticastAddress()) hasIpv6Unicast = true;
+				}
+			}
+			return hasIpv6Unicast;
+		} catch (SocketException e) {
+			logException(LOG, WARNING, e);
+			return false;
+		}
 	}
 
 	private void updateConnectionStatus() {

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

@@ -6,8 +6,6 @@ import android.bluetooth.BluetoothAdapter;
 import android.bluetooth.BluetoothDevice;
 import android.content.ContentResolver;
 import android.content.Context;
-import android.net.wifi.WifiConfiguration;
-import android.net.wifi.WifiManager;
 import android.os.Build;
 import android.os.Parcel;
 import android.os.StrictMode;
@@ -17,12 +15,10 @@ import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 
 import java.io.DataOutputStream;
 import java.io.IOException;
-import java.util.List;
 
 import javax.annotation.concurrent.Immutable;
 import javax.inject.Inject;
 
-import static android.content.Context.WIFI_SERVICE;
 import static android.os.Build.VERSION.SDK_INT;
 import static android.provider.Settings.Secure.ANDROID_ID;
 
@@ -52,15 +48,6 @@ class AndroidSecureRandomProvider extends UnixSecureRandomProvider {
 		String id = Settings.Secure.getString(contentResolver, ANDROID_ID);
 		if (id != null) out.writeUTF(id);
 		Parcel parcel = Parcel.obtain();
-		WifiManager wm = (WifiManager) appContext.getApplicationContext()
-				.getSystemService(WIFI_SERVICE);
-		if (wm != null) {
-			List<WifiConfiguration> configs = wm.getConfiguredNetworks();
-			if (configs != null) {
-				for (WifiConfiguration config : configs)
-					parcel.writeParcelable(config, 0);
-			}
-		}
 		BluetoothAdapter bt = BluetoothAdapter.getDefaultAdapter();
 		if (bt != null) {
 			for (BluetoothDevice device : bt.getBondedDevices())

bramble-android/witness.gradle

@@ -1,33 +1,36 @@
 dependencyVerification {
     verify = [
         'cglib:cglib:3.2.0:cglib-3.2.0.jar:adb13bab79712ad6bdf1bd59f2a3918018a8016e722e8a357065afb9e6690861',
-        'com.android.tools.analytics-library:protos:26.5.1:protos-26.5.1.jar:8dde1130725461fe827f2a343d353f2b51e8870661fc860d7d5ebddb097ead4e',
+        'com.android.tools.analytics-library:protos:27.1.1:protos-27.1.1.jar:13f77e73762e58ab372d140b3a6be6903aea9775b62dd14fbc62d4cc7069c9a4',
-        'com.android.tools.analytics-library:shared:26.5.1:shared-26.5.1.jar:ccc2f3b00ec17b11401610ba68553544fc8fc517120e84439ac6eb86b875e18d',
+        'com.android.tools.analytics-library:shared:27.1.1:shared-27.1.1.jar:82930a52001410e97d809930b670f4de3002286975f046b9de5f6b777b06d366',
-        'com.android.tools.analytics-library:tracker:26.5.1:tracker-26.5.1.jar:3a76984c0fe2e847ca7a8b35b4780ef0447a9d1666946cb8e60466318e0ab5ae',
+        'com.android.tools.analytics-library:tracker:27.1.1:tracker-27.1.1.jar:31bc5a00be0055bac89c9b2f34751883e987cd89e3ac1783720645c164f591d9',
-        'com.android.tools.build:aapt2-proto:0.4.0:aapt2-proto-0.4.0.jar:fac0435e08898f89eeeb9ca236bea707155ff816c12205ced285ad53604133ca',
+        'com.android.tools.build:aapt2-proto:4.1.0-alpha01-6193524:aapt2-proto-4.1.0-alpha01-6193524.jar:17e75523e1e92dd4f222c7368ee41df9e964a508232f591e265d0c499baf9dca',
-        'com.android.tools.build:apksig:3.5.1:apksig-3.5.1.jar:1fd33e7f009a2a0da766cfeec4211a09f548034b015c289a66d75dd8a9302f4a',
+        'com.android.tools.build:apksig:4.1.1:apksig-4.1.1.jar:e0a69da9e5a03986d608b45bbf954ef0e6a0b3f58c1b8315bd169ec08b279e72',
-        'com.android.tools.build:apkzlib:3.5.1:apkzlib-3.5.1.jar:9f330167cbe973b7db407692f74f4f6453b7ffa5f2048934b06280c2ceee60fa',
+        'com.android.tools.build:apkzlib:4.1.1:apkzlib-4.1.1.jar:ba4b5e419b6be0130eae7f8301c3a551ad3976f487d2e0c6852ebb175ac41127',
-        'com.android.tools.build:builder-model:3.5.1:builder-model-3.5.1.jar:39ea3c82b76b6e0c9f9fa88d93e0edc1dd4a0f1dfae0ef6fbf2d451da47e5450',
+        'com.android.tools.build:builder-model:4.1.1:builder-model-4.1.1.jar:e95c99cc298ad67b8deb6ced99c51abc8f59afebedad044b1a10dde14646a4dd',
-        'com.android.tools.build:builder-test-api:3.5.1:builder-test-api-3.5.1.jar:a1b59305584cbcaa078fdc9cfb80871012755b822dd32e8da19add6f7bbcb762',
+        'com.android.tools.build:builder-test-api:4.1.1:builder-test-api-4.1.1.jar:464f596ab261c051c3847406748e843770dea123f6fa5fee8a9390644e709b7a',
-        'com.android.tools.build:builder:3.5.1:builder-3.5.1.jar:e3a8d382434c5f60990730c4719fc814e85a898a33a1e96c1df8d627d3c6eea6',
+        'com.android.tools.build:builder:4.1.1:builder-4.1.1.jar:0f78d4759d2f7b57b95865522ec34596ba419b9982f3b25e3449213f9c98b80d',
-        'com.android.tools.build:gradle-api:3.5.1:gradle-api-3.5.1.jar:be9b41859bace11998f66b04ed944f87e413f3ad6da3c4665587699da125addc',
+        'com.android.tools.build:gradle-api:4.1.1:gradle-api-4.1.1.jar:d42e6b539e4c1353ad3546e75ec8ce11a017b97481023e8ea18577eefe374358',
-        'com.android.tools.build:manifest-merger:26.5.1:manifest-merger-26.5.1.jar:dcad9ecb967251f4d750f55a4204a2b400e8fbfe5cb930a1d0d5dbe10ae8bdfc',
+        'com.android.tools.build:manifest-merger:27.1.1:manifest-merger-27.1.1.jar:7a45fa143687859bb2e5a961dcf6ee88094d3853de0cb543dc03dbcb0f4b554b',
-        'com.android.tools.ddms:ddmlib:26.5.1:ddmlib-26.5.1.jar:b081aef2a4ed3f4d47cae4cdb128469735f25a114e026d37123bf9ffdec742a8',
+        'com.android.tools.ddms:ddmlib:27.1.1:ddmlib-27.1.1.jar:da6e4bd834b6a85dae8019039849d8bd96933347dfbf460df74913ddade6e40a',
-        'com.android.tools.external.com-intellij:intellij-core:26.5.1:intellij-core-26.5.1.jar:20eced30adc124805bd93488d9cd9d3e33e6bf7b48e9fe5a703d4983f894d450',
+        'com.android.tools.external.com-intellij:intellij-core:27.1.1:intellij-core-27.1.1.jar:2591a7363c4443c59bf9f793730acafce9d6ec3076e2f46716edaf53a41b6fb6',
-        'com.android.tools.external.com-intellij:kotlin-compiler:26.5.1:kotlin-compiler-26.5.1.jar:5aed762dd54875b77ae7018d97c05756ff0c5b9fd02ec595dd396ccd14cc22cb',
+        'com.android.tools.external.com-intellij:kotlin-compiler:27.1.1:kotlin-compiler-27.1.1.jar:5054ae770ba788f110303c65abd6b1fa28eccf52dee1274510e201b2b81885c8',
-        'com.android.tools.external.org-jetbrains:uast:26.5.1:uast-26.5.1.jar:4bc8653d6c0943f40fee963a149e36c6baa45683d2530968a13f5007e3c40740',
+        'com.android.tools.external.org-jetbrains:uast:27.1.1:uast-27.1.1.jar:54cd8f6886a9d2f5641659dd5c91f626629672cd48301f7f0bd6aad9bd448714',
-        'com.android.tools.layoutlib:layoutlib-api:26.5.1:layoutlib-api-26.5.1.jar:88732f11396c427273e515d23042e35633f4fe4295528a99b866aa2adf0efd9c',
+        'com.android.tools.layoutlib:layoutlib-api:27.1.1:layoutlib-api-27.1.1.jar:8a9a22e3b309521ea83b724e5a89cfdac6076f52d675c0e17d77b05527bc0f8c',
-        'com.android.tools.lint:lint-api:26.5.1:lint-api-26.5.1.jar:ec33fcd72bfaf70dd841e03fbfd93f109c2e575aec146067c606689c3972f0de',
+        'com.android.tools.lint:lint-api:27.1.1:lint-api-27.1.1.jar:c1d8176094cb0478786070d40533efb578ebc53529a82f6ef5bee879bdca418b',
-        'com.android.tools.lint:lint-checks:26.5.1:lint-checks-26.5.1.jar:a1b9607d484aaae7a71dcecdc76f8003d8239af226c776894a2cf63f9e6c60d7',
+        'com.android.tools.lint:lint-checks:27.1.1:lint-checks-27.1.1.jar:3899c91e00bd059b40c31a9ca00cd0f8303191947608735ae1b657323693fb61',
-        'com.android.tools.lint:lint-gradle-api:26.5.1:lint-gradle-api-26.5.1.jar:82453fd98a8394cc84ed995c04d2cd744abd1d6589403427ba7eef53115406f3',
+        'com.android.tools.lint:lint-gradle-api:27.1.1:lint-gradle-api-27.1.1.jar:26aa89d38b9825cc73229daa82a68875801c8b8491f30497ce62aff1f206eb0d',
-        'com.android.tools.lint:lint-gradle:26.5.1:lint-gradle-26.5.1.jar:59465b56cf7db77c656d5f8195d721c3d48b6bdd0502d774de335bfe4baff00b',
+        'com.android.tools.lint:lint-gradle:27.1.1:lint-gradle-27.1.1.jar:f7355823ead869f4d28184ba28b7a0c693b507519a2d3705bb9848a0f35b3756',
-        'com.android.tools.lint:lint:26.5.1:lint-26.5.1.jar:336e4b04ec6f8b0f25879131b7a7862d77df83a1879ee5b71be26128755f8e2e',
+        'com.android.tools.lint:lint-model:27.1.1:lint-model-27.1.1.jar:bc23c0c413bdfca59dac2cd56b870d8360d009e9ec0d365e71f774bcf127971d',
-        'com.android.tools:annotations:26.5.1:annotations-26.5.1.jar:2c43c82f8c59d8f7a61e3239e1a2dc9f69dc342ec09af9b7c9f69b25337c0b6e',
+        'com.android.tools.lint:lint:27.1.1:lint-27.1.1.jar:2f6038a5398a42bd591883c3f5e5894f4ec52ca1c3683bf94fa8553c1700af81',
-        'com.android.tools:common:26.5.1:common-26.5.1.jar:eccfa54486ed54c4e3123cc42195d023bd0dd21bcd2f0e4868e8c6fc70f8ef6b',
+        'com.android.tools:annotations:27.1.1:annotations-27.1.1.jar:ff28c504d2acb9fd1a5ffbd97ae85cf59ee18c76927525aad250509bccf2cab1',
-        'com.android.tools:dvlib:26.5.1:dvlib-26.5.1.jar:46f93ad498b4756e7d867d2fe38c38890a80e7407a4ae459e4a8c8d5c5aeacfe',
+        'com.android.tools:common:27.1.1:common-27.1.1.jar:63d9a2a9ad6d278db319f3749b9f50bdf5457ef7020074a1bebe124e714b535c',
-        'com.android.tools:repository:26.5.1:repository-26.5.1.jar:2b3ee791aa4c3e8ce60498c161a27ca7228816fc630eed4d9f25f2f36a106dce',
+        'com.android.tools:dvlib:27.1.1:dvlib-27.1.1.jar:998a54201fc1cefee5f2399215e95c42b1f64f9e1d8f4452eb8255c68ba5440f',
-        'com.android.tools:sdk-common:26.5.1:sdk-common-26.5.1.jar:365f749676c3574676fd465177c8a492f340816db2b520d6ed114d3b6e77bea7',
+        'com.android.tools:repository:27.1.1:repository-27.1.1.jar:d25b74ccabf4d876903efb375e9af6fb380d8ae0445bb74bbdcc225c1e37fa1d',
-        'com.android.tools:sdklib:26.5.1:sdklib-26.5.1.jar:007da104afb27c8c682a1628023fe9ec438249c8d15ef0fd6624c5bb8e23b696',
+        'com.android.tools:sdk-common:27.1.1:sdk-common-27.1.1.jar:4473ae97d0ef7061ee1de61041d5aa97405ae08e44c09cf7bb278b42e4b97c7c',
+        'com.android.tools:sdklib:27.1.1:sdklib-27.1.1.jar:08e6b83961ac9724b3c1e3d0eff971f13be6701292c77914b8794480f3391250',
+        'com.android:signflinger:4.1.1:signflinger-4.1.1.jar:0c66825988873ec2d51057fa463f54a8f18fc7326ff4530b9da363b71e97ce60',
+        'com.android:zipflinger:4.1.1:zipflinger-4.1.1.jar:0a8c3e52ac13dd031236f9fb5ba4408b1d5dcd12325a05440b36da09d8881446',
         'com.google.code.findbugs:jsr305:3.0.2:jsr305-3.0.2.jar:766ad2a0783f2687962c8ad74ceecc38a28b9f72a2d085ee438b7813e928d0c7',
         'com.google.code.gson:gson:2.8.5:gson-2.8.5.jar:233a0149fc365c9f6edbd683cfe266b19bdc773be98eabdaf6b3c924b48e7d81',
         'com.google.dagger:dagger-compiler:2.24:dagger-compiler-2.24.jar:3c5afb955fb188da485cb2c048eff37dce0e1530b9780a0f2f7187d16d1ccc1f',
@@ -35,27 +38,30 @@ dependencyVerification {
         'com.google.dagger:dagger-spi:2.24:dagger-spi-2.24.jar:c038445d14dbcb4054e61bf49e05009edf26fce4fdc7ec1a9db544784f68e718',
         'com.google.dagger:dagger:2.24:dagger-2.24.jar:550a6e46a6dfcdf1d764887b6090cea94f783327e50e5c73754f18facfc70b64',
         'com.google.errorprone:error_prone_annotations:2.2.0:error_prone_annotations-2.2.0.jar:6ebd22ca1b9d8ec06d41de8d64e0596981d9607b42035f9ed374f9de271a481a',
+        'com.google.errorprone:error_prone_annotations:2.3.2:error_prone_annotations-2.3.2.jar:357cd6cfb067c969226c442451502aee13800a24e950fdfde77bcdb4565a668d',
         'com.google.errorprone:javac-shaded:9-dev-r4023-3:javac-shaded-9-dev-r4023-3.jar:65bfccf60986c47fbc17c9ebab0be626afc41741e0a6ec7109e0768817a36f30',
         'com.google.googlejavaformat:google-java-format:1.5:google-java-format-1.5.jar:aa19ad7850fb85178aa22f2fddb163b84d6ce4d0035872f30d4408195ca1144e',
         'com.google.guava:failureaccess:1.0.1:failureaccess-1.0.1.jar:a171ee4c734dd2da837e4b16be9df4661afab72a41adaf31eb84dfdaf936ca26',
-        'com.google.guava:guava:27.0.1-jre:guava-27.0.1-jre.jar:e1c814fd04492a27c38e0317eabeaa1b3e950ec8010239e400fe90ad6c9107b4',
         'com.google.guava:guava:27.1-jre:guava-27.1-jre.jar:4a5aa70cc968a4d137e599ad37553e5cfeed2265e8c193476d7119036c536fe7',
+        'com.google.guava:guava:28.1-jre:guava-28.1-jre.jar:30beb8b8527bd07c6e747e77f1a92122c2f29d57ce347461a4a55eb26e382da4',
         'com.google.guava:listenablefuture:9999.0-empty-to-avoid-conflict-with-guava:listenablefuture-9999.0-empty-to-avoid-conflict-with-guava.jar:b372a037d4230aa57fbeffdef30fd6123f9c0c2db85d0aced00c91b974f33f99',
         'com.google.j2objc:j2objc-annotations:1.1:j2objc-annotations-1.1.jar:2994a7eb78f2710bd3d3bfb639b2c94e219cedac0d4d084d516e78c16dddecf6',
+        'com.google.j2objc:j2objc-annotations:1.3:j2objc-annotations-1.3.jar:21af30c92267bd6122c0e0b4d20cccb6641a37eaf956c6540ec471d584e64a7b',
         'com.google.jimfs:jimfs:1.1:jimfs-1.1.jar:c4828e28d7c0a930af9387510b3bada7daa5c04d7c25a75c7b8b081f1c257ddd',
-        'com.google.protobuf:protobuf-java:3.4.0:protobuf-java-3.4.0.jar:dce7e66b32456a1b1198da0caff3a8acb71548658391e798c79369241e6490a4',
+        'com.google.protobuf:protobuf-java:3.10.0:protobuf-java-3.10.0.jar:161d7d61a8cb3970891c299578702fd079646e032329d6c2cabf998d191437c9',
         'com.googlecode.json-simple:json-simple:1.1:json-simple-1.1.jar:2d9484f4c649f708f47f9a479465fc729770ee65617dca3011836602264f6439',
         'com.squareup:javapoet:1.11.1:javapoet-1.11.1.jar:9cbf2107be499ec6e95afd36b58e3ca122a24166cdd375732e51267d64058e90',
         'com.squareup:javawriter:2.5.0:javawriter-2.5.0.jar:fcfb09fb0ea0aa97d3cfe7ea792398081348e468f126b3603cb3803f240197f0',
         'com.sun.activation:javax.activation:1.2.0:javax.activation-1.2.0.jar:993302b16cd7056f21e779cc577d175a810bb4900ef73cd8fbf2b50f928ba9ce',
-        'com.sun.istack:istack-commons-runtime:2.21:istack-commons-runtime-2.21.jar:c33e67a0807095f02a0e2da139412dd7c4f9cc1a4c054b3e434f96831ba950f4',
+        'com.sun.istack:istack-commons-runtime:3.0.7:istack-commons-runtime-3.0.7.jar:6443e10ba2e259fb821d9b6becf10db5316285fc30c53cec9d7b19a3877e7fdf',
-        'com.sun.xml.fastinfoset:FastInfoset:1.2.13:FastInfoset-1.2.13.jar:27a77db909f3c2833c0b1a37c55af1db06045118ad2eed96ce567b6632bce038',
+        'com.sun.xml.fastinfoset:FastInfoset:1.2.15:FastInfoset-1.2.15.jar:785861db11ca1bd0d1956682b974ad73eb19cd3e01a4b3fa82d62eca97210aec',
         'commons-codec:commons-codec:1.10:commons-codec-1.10.jar:4241dfa94e711d435f29a4604a3e2de5c4aa3c165e23bd066be6fc1fc4309569',
         'commons-logging:commons-logging:1.2:commons-logging-1.2.jar:daddea1ea0be0f56978ab3006b8ac92834afeefbd9b7e4e6316fca57df0fa636',
         'it.unimi.dsi:fastutil:7.2.0:fastutil-7.2.0.jar:74fa208043740642f7e6eb09faba15965218ad2f50ce3020efb100136e4b591c',
+        'javax.activation:javax.activation-api:1.2.0:javax.activation-api-1.2.0.jar:43fdef0b5b6ceb31b0424b208b930c74ab58fac2ceeb7b3f6fd3aeb8b5ca4393',
         'javax.annotation:jsr250-api:1.0:jsr250-api-1.0.jar:a1a922d0d9b6d183ed3800dfac01d1e1eb159f0e8c6f94736931c1def54a941f',
         'javax.inject:javax.inject:1:javax.inject-1.jar:91c77044a50c481636c32d916fd89c9118a72195390452c81065080f957de7ff',
-        'javax.xml.bind:jaxb-api:2.2.12-b140109.1041:jaxb-api-2.2.12-b140109.1041.jar:b5e60cd8b7b5ff01ce4a74c5dd008f4fbd14ced3495d0b47b85cfedc182211f2',
+        'javax.xml.bind:jaxb-api:2.3.1:jaxb-api-2.3.1.jar:88b955a0df57880a26a74708bc34f74dcaf8ebf4e78843a28b50eae945732b06',
         'junit:junit:4.12:junit-4.12.jar:59721f0805e223d84b90677887d9ff567dc534d7c502ca903c0c2b17f05c116a',
         'net.ltgt.gradle.incap:incap:0.2:incap-0.2.jar:b625b9806b0f1e4bc7a2e3457119488de3cd57ea20feedd513db070a573a4ffd',
         'net.sf.jopt-simple:jopt-simple:4.9:jopt-simple-4.9.jar:26c5856e954b5f864db76f13b86919b59c6eecf9fd930b96baa8884626baf2f5',
@@ -70,34 +76,35 @@ dependencyVerification {
         'org.bouncycastle:bcpkix-jdk15on:1.56:bcpkix-jdk15on-1.56.jar:7043dee4e9e7175e93e0b36f45b1ec1ecb893c5f755667e8b916eb8dd201c6ca',
         'org.bouncycastle:bcprov-jdk15on:1.56:bcprov-jdk15on-1.56.jar:963e1ee14f808ffb99897d848ddcdb28fa91ddda867eb18d303e82728f878349',
         'org.briarproject:obfs4proxy-android:0.0.11-2:obfs4proxy-android-0.0.11-2.zip:57e55cbe87aa2aac210fdbb6cd8cdeafe15f825406a08ebf77a8b787aa2c6a8a',
-        'org.briarproject:tor-android:0.3.5.10:tor-android-0.3.5.10.zip:edd83bf557fcff2105eaa0bdb3f607a6852ebe7360920929ae3039dd5f4774c5',
+        'org.briarproject:tor-android:0.3.5.12:tor-android-0.3.5.12.zip:db71fb3290acff79d572af0752570eaf6aad7c4d88c9b9aa0b4d5afe2b9ead9c',
         'org.checkerframework:checker-compat-qual:2.5.3:checker-compat-qual-2.5.3.jar:d76b9afea61c7c082908023f0cbc1427fab9abd2df915c8b8a3e7a509bccbc6d',
         'org.checkerframework:checker-qual:2.5.2:checker-qual-2.5.2.jar:64b02691c8b9d4e7700f8ee2e742dce7ea2c6e81e662b7522c9ee3bf568c040a',
+        'org.checkerframework:checker-qual:2.8.1:checker-qual-2.8.1.jar:9103499008bcecd4e948da29b17864abb64304e15706444ae209d17ebe0575df',
         'org.codehaus.groovy:groovy-all:2.4.15:groovy-all-2.4.15.jar:51d6c4e71782e85674239189499854359d380fb75e1a703756e3aaa5b98a5af0',
         'org.codehaus.mojo:animal-sniffer-annotations:1.17:animal-sniffer-annotations-1.17.jar:92654f493ecfec52082e76354f0ebf87648dc3d5cec2e3c3cdb947c016747a53',
-        'org.glassfish.jaxb:jaxb-core:2.2.11:jaxb-core-2.2.11.jar:37bcaee8ebb04362c8352a5bf6221b86967ecdab5164c696b10b9a2bb587b2aa',
+        'org.codehaus.mojo:animal-sniffer-annotations:1.18:animal-sniffer-annotations-1.18.jar:47f05852b48ee9baefef80fa3d8cea60efa4753c0013121dd7fe5eef2e5c729d',
-        'org.glassfish.jaxb:jaxb-runtime:2.2.11:jaxb-runtime-2.2.11.jar:a874f2351cfba8e2946be3002d10c18a6da8f21b52ba2acf52f2b85d5520ed70',
+        'org.glassfish.jaxb:jaxb-runtime:2.3.1:jaxb-runtime-2.3.1.jar:45fecfa5c8217ce1f3652ab95179790ec8cc0dec0384bca51cbeb94a293d9f2f',
-        'org.glassfish.jaxb:txw2:2.2.11:txw2-2.2.11.jar:272a3ccad45a4511351920cd2a8633c53cab8d5220c7a92954da5526bb5eafea',
+        'org.glassfish.jaxb:txw2:2.3.1:txw2-2.3.1.jar:34975dde1c6920f1a39791142235689bc3cd357e24d05edd8ff93b885bd68d60',
         'org.hamcrest:hamcrest-core:1.3:hamcrest-core-1.3.jar:66fdef91e9739348df7a096aa384a5685f4e875584cce89386a7a47251c4d8e9',
         'org.hamcrest:hamcrest-library:1.3:hamcrest-library-1.3.jar:711d64522f9ec410983bd310934296da134be4254a125080a0416ec178dfad1c',
-        'org.jetbrains.kotlin:kotlin-reflect:1.3.50:kotlin-reflect-1.3.50.jar:64583199ea5a54aefd1bd1595288925f784226ee562d1dd279011c6075b3d7a4',
+        'org.jetbrains.kotlin:kotlin-reflect:1.3.72:kotlin-reflect-1.3.72.jar:a188d9367de1c4ee9479db630985c0597b20709c83161b1430d24edb27e38c40',
-        'org.jetbrains.kotlin:kotlin-stdlib-common:1.3.50:kotlin-stdlib-common-1.3.50.jar:8ce678e88e4ba018b66dacecf952471e4d7dfee156a8a819760a5a5ff29d323c',
+        'org.jetbrains.kotlin:kotlin-stdlib-common:1.3.72:kotlin-stdlib-common-1.3.72.jar:5e7d1552863e480c1628b1cc39ce230ef829f5b7230106215a05acda5172203a',
-        'org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.3.50:kotlin-stdlib-jdk7-1.3.50.jar:9a026639e76212f8d57b86d55b075394c2e009f1979110751d34c05c5f75d57b',
+        'org.jetbrains.kotlin:kotlin-stdlib-jdk7:1.3.72:kotlin-stdlib-jdk7-1.3.72.jar:40566c0c08d414b9413ba556ff7f8a0b04b98b9f0f424d122dd2088510efccc4',
-        'org.jetbrains.kotlin:kotlin-stdlib-jdk8:1.3.50:kotlin-stdlib-jdk8-1.3.50.jar:1b351fb6e09c14b55525c74c1f4cf48942eae43c348b7bc764a5e6e423d4da0c',
+        'org.jetbrains.kotlin:kotlin-stdlib-jdk8:1.3.72:kotlin-stdlib-jdk8-1.3.72.jar:133da70cfc07b56094282eac5c59bccd59f167ee2ead22e5282876d8bc10bf95',
-        'org.jetbrains.kotlin:kotlin-stdlib:1.3.50:kotlin-stdlib-1.3.50.jar:e6f05746ee0366d0b52825a090fac474dcf44082c9083bbb205bd16976488d6c',
+        'org.jetbrains.kotlin:kotlin-stdlib:1.3.72:kotlin-stdlib-1.3.72.jar:3856a7349ebacd6d1be6802b2fed9c4dc2c5a564ea92b6b945ac988243d4b16b',
         'org.jetbrains.trove4j:trove4j:20160824:trove4j-20160824.jar:1917871c8deb468307a584680c87a44572f5a8b0b98c6d397fc0f5f86596dbe7',
         'org.jetbrains:annotations:13.0:annotations-13.0.jar:ace2a10dc8e2d5fd34925ecac03e4988b2c0f851650c94b8cef49ba1bd111478',
         'org.jmock:jmock-junit4:2.8.2:jmock-junit4-2.8.2.jar:f7ee4df4f7bd7b7f1cafad3b99eb74d579f109d5992ff625347352edb55e674c',
         'org.jmock:jmock-legacy:2.8.2:jmock-legacy-2.8.2.jar:f2b985a5c08a9edb7f37612330c058809da3f6a6d63ce792426ebf8ff0d6d31b',
         'org.jmock:jmock-testjar:2.8.2:jmock-testjar-2.8.2.jar:8900860f72c474e027cf97fe78dcbf154a1aa7fc62b6845c5fb4e4f3c7bc8760',
         'org.jmock:jmock:2.8.2:jmock-2.8.2.jar:6c73cb4a2e6dbfb61fd99c9a768539c170ab6568e57846bd60dbf19596b65b16',
-        'org.jvnet.staxex:stax-ex:1.7.7:stax-ex-1.7.7.jar:a31ff7d77163c0deb09e7fee59ad35ae44c2cee2cc8552a116ccd1583d813fb4',
+        'org.jvnet.staxex:stax-ex:1.8:stax-ex-1.8.jar:95b05d9590af4154c6513b9c5dc1fb2e55b539972ba0a9ef28e9a0c01d83ad77',
         'org.objenesis:objenesis:2.1:objenesis-2.1.jar:c74330cc6b806c804fd37e74487b4fe5d7c2750c5e15fbc6efa13bdee1bdef80',
-        'org.ow2.asm:asm-analysis:6.0:asm-analysis-6.0.jar:2f1a6387219c3a6cc4856481f221b03bd9f2408a326d416af09af5d6f608c1f4',
+        'org.ow2.asm:asm-analysis:7.0:asm-analysis-7.0.jar:e981f8f650c4d900bb033650b18e122fa6b161eadd5f88978d08751f72ee8474',
-        'org.ow2.asm:asm-commons:6.0:asm-commons-6.0.jar:f1bce5c648a96a017bdcd01fe5d59af9845297fd7b79b81c015a6fbbd9719abf',
+        'org.ow2.asm:asm-commons:7.0:asm-commons-7.0.jar:fed348ef05958e3e846a3ac074a12af5f7936ef3d21ce44a62c4fa08a771927d',
-        'org.ow2.asm:asm-tree:6.0:asm-tree-6.0.jar:887998fb69727c8759e4d253f856822801e33f9fd4caa566b3ac58ee92106215',
+        'org.ow2.asm:asm-tree:7.0:asm-tree-7.0.jar:cfd7a0874f9de36a999c127feeadfbfe6e04d4a71ee954d7af3d853f0be48a6c',
-        'org.ow2.asm:asm-util:6.0:asm-util-6.0.jar:356afebdb0f870175262e5188f8709a3b17aa2a5a6a4b0340b04d4b449bca5f6',
+        'org.ow2.asm:asm-util:7.0:asm-util-7.0.jar:75fbbca440ef463f41c2b0ab1a80abe67e910ac486da60a7863cbcb5bae7e145',
         'org.ow2.asm:asm:5.0.4:asm-5.0.4.jar:896618ed8ae62702521a78bc7be42b7c491a08e6920a15f89a3ecdec31e9a220',
-        'org.ow2.asm:asm:6.0:asm-6.0.jar:dd8971c74a4e697899a8e95caae4ea8760ea6c486dc6b97b1795e75760420461',
+        'org.ow2.asm:asm:7.0:asm-7.0.jar:b88ef66468b3c978ad0c97fd6e90979e56155b4ac69089ba7a44e9aa7ffe9acf',
     ]
 }

bramble-api/src/main/java/org/briarproject/bramble/api/network/NetworkStatus.java

@@ -8,11 +8,12 @@ import javax.annotation.concurrent.Immutable;
 @NotNullByDefault
 public class NetworkStatus {
 
-	private final boolean connected, wifi;
+	private final boolean connected, wifi, ipv6Only;
 
-	public NetworkStatus(boolean connected, boolean wifi) {
+	public NetworkStatus(boolean connected, boolean wifi, boolean ipv6Only) {
 		this.connected = connected;
 		this.wifi = wifi;
+		this.ipv6Only = ipv6Only;
 	}
 
 	public boolean isConnected() {
@@ -22,4 +23,8 @@ public class NetworkStatus {
 	public boolean isWifi() {
 		return wifi;
 	}
+
+	public boolean isIpv6Only() {
+		return ipv6Only;
+	}
 }

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

@@ -23,6 +23,8 @@ public interface DevReporter {
 
 	/**
 	 * Sends any reports previously stored on disk.
+	 *
+	 * @return The number of reports that were sent.
 	 */
-	void sendReports();
+	int sendReports();
 }

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

@@ -11,6 +11,7 @@ import org.briarproject.bramble.api.system.Clock;
 import org.briarproject.bramble.util.Base32;
 
 import java.security.GeneralSecurityException;
+import java.util.Locale;
 import java.util.regex.Matcher;
 
 import javax.inject.Inject;
@@ -52,7 +53,7 @@ class PendingContactFactoryImpl implements PendingContactFactory {
 		byte[] raw = new byte[RAW_LINK_BYTES];
 		raw[0] = FORMAT_VERSION;
 		arraycopy(encoded, 0, raw, 1, encoded.length);
-		return "briar://" + Base32.encode(raw).toLowerCase();
+		return "briar://" + Base32.encode(raw).toLowerCase(Locale.US);
 	}
 
 	private PublicKey parseHandshakeLink(String link) throws FormatException {

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());
+			descriptors.put(d.getId(), d);
-			if (p instanceof DuplexPlugin) {
+		}
+		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());
+					LOG.info("Connecting via " + id);
-				DuplexPlugin plugin = (DuplexPlugin) p;
+				transports.add(new Pair<>((DuplexPlugin) p, d.getDescriptor()));
-				byte[] commitment = remotePayload.getCommitment();
-				BdfList descriptor = d.getDescriptor();
-				connectionChooser.submit(new ReadableTask(
-						new ConnectorTask(plugin, commitment, descriptor)));
 			}
 		}
 
+		// 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,
+		private ConnectorTask(List<Pair<DuplexPlugin, BdfList>> transports,
-				BdfList descriptor) {
+				byte[] commitment) {
-			this.plugin = plugin;
+			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 =
+				for (Pair<DuplexPlugin, BdfList> pair : transports) {
-						plugin.createKeyAgreementConnection(commitment,
+					if (stopped) return null;
-								descriptor);
+					DuplexPlugin plugin = pair.getFirst();
-				if (conn != null) {
+					BdfList descriptor = pair.getSecond();
-					if (LOG.isLoggable(INFO))
+					DuplexTransportConnection conn =
-						LOG.info(plugin.getId() + ": Outgoing connection");
+							plugin.createKeyAgreementConnection(commitment,
-					return new KeyAgreementConnection(conn, plugin.getId());
+									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/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))
+			if (LOG.isLoggable(INFO)) {
-				LOG.info("Discovering address for key agreement UUID " + uuid);
+				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
+			installTorExecutable();
-			in = getTorInputStream();
+			installObfs4Executable();
-			out = new FileOutputStream(torFile);
+			extract(getGeoIpInputStream(), geoIpFile);
-			copyAndClose(in, out);
+			extract(getConfigInputStream(), configFile);
-			// 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);
 			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());
@@ -858,6 +863,7 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 			if (!state.isTorRunning()) return;
 			boolean online = status.isConnected();
 			boolean wifi = status.isWifi();
+			boolean ipv6Only = status.isIpv6Only();
 			String country = locationUtils.getCurrentCountry();
 			boolean blocked =
 					circumventionProvider.isTorProbablyBlocked(country);
@@ -874,7 +880,8 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 			boolean automatic = network == PREF_TOR_NETWORK_AUTOMATIC;
 
 			if (LOG.isLoggable(INFO)) {
-				LOG.info("Online: " + online + ", wifi: " + wifi);
+				LOG.info("Online: " + online + ", wifi: " + wifi
+						+ ", IPv6 only: " + ipv6Only);
 				if (country.isEmpty()) LOG.info("Country code unknown");
 				else LOG.info("Country code: " + country);
 				LOG.info("Charging: " + charging);
@@ -911,7 +918,8 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 					enableNetwork = true;
 					if (network == PREF_TOR_NETWORK_WITH_BRIDGES ||
 							(automatic && bridgesWork)) {
-						if (circumventionProvider.needsMeek(country)) {
+						if (ipv6Only ||
+								circumventionProvider.needsMeek(country)) {
 							LOG.info("Using meek bridges");
 							enableBridges = true;
 							useMeek = true;
@@ -937,6 +945,7 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 				if (enableNetwork) {
 					enableBridges(enableBridges, useMeek);
 					enableConnectionPadding(enableConnectionPadding);
+					useIpv6(ipv6Only);
 				}
 				enableNetwork(enableNetwork);
 			} catch (IOException e) {
@@ -949,6 +958,11 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 		controlConnection.setConf("ConnectionPadding", enable ? "1" : "0");
 	}
 
+	private void useIpv6(boolean ipv6Only) throws IOException {
+		controlConnection.setConf("ClientUseIPv4", ipv6Only ? "0" : "1");
+		controlConnection.setConf("ClientUseIPv6", ipv6Only ? "1" : "0");
+	}
+
 	@ThreadSafe
 	@NotNullByDefault
 	protected class PluginState {

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

@@ -29,6 +29,7 @@ import javax.annotation.concurrent.Immutable;
 import javax.inject.Inject;
 import javax.net.SocketFactory;
 
+import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
 import static org.briarproject.bramble.util.IoUtils.tryToClose;
 
@@ -100,11 +101,12 @@ class DevReporterImpl implements DevReporter, EventListener {
 	}
 
 	@Override
-	public void sendReports() {
+	public int sendReports() {
 		File reportDir = devConfig.getReportDir();
 		File[] reports = reportDir.listFiles();
+		int reportsSent = 0;
 		if (reports == null || reports.length == 0)
-			return; // No reports to send
+			return reportsSent; // No reports to send
 
 		LOG.info("Sending reports to developers");
 		for (File f : reports) {
@@ -116,13 +118,15 @@ class DevReporterImpl implements DevReporter, EventListener {
 				in = new FileInputStream(f);
 				IoUtils.copyAndClose(in, out);
 				f.delete();
+				reportsSent++;
 			} catch (IOException e) {
 				LOG.log(WARNING, "Failed to send reports", e);
 				tryToClose(out, LOG, WARNING);
 				tryToClose(in, LOG, WARNING);
-				return;
+				return reportsSent;
 			}
 		}
-		LOG.info("Reports sent");
+		if (LOG.isLoggable(INFO)) LOG.info(reportsSent + " report(s) sent");
+		return reportsSent;
 	}
 }

bramble-java/build.gradle

@@ -16,7 +16,7 @@ dependencies {
 	implementation fileTree(dir: 'libs', include: '*.jar')
 	implementation 'net.java.dev.jna:jna:4.5.2'
 	implementation 'net.java.dev.jna:jna-platform:4.5.2'
-	tor 'org.briarproject:tor:0.3.5.10@zip'
+	tor 'org.briarproject:tor:0.3.5.12@zip'
 	tor 'org.briarproject:obfs4proxy:0.0.7@zip'
 
 	annotationProcessor 'com.google.dagger:dagger-compiler:2.24'

bramble-java/src/main/java/org/briarproject/bramble/network/JavaNetworkManager.java

@@ -5,6 +5,8 @@ import org.briarproject.bramble.api.network.NetworkStatus;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 
+import java.net.Inet4Address;
+import java.net.InetAddress;
 import java.net.NetworkInterface;
 import java.net.SocketException;
 import java.util.Enumeration;
@@ -14,8 +16,8 @@ import javax.inject.Inject;
 
 import static java.net.NetworkInterface.getNetworkInterfaces;
 import static java.util.Collections.list;
-import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
+import static java.util.logging.Logger.getLogger;
 import static org.briarproject.bramble.util.LogUtils.logException;
 
 @MethodsNotNullByDefault
@@ -23,7 +25,7 @@ import static org.briarproject.bramble.util.LogUtils.logException;
 class JavaNetworkManager implements NetworkManager {
 
 	private static final Logger LOG =
-			Logger.getLogger(JavaNetworkManager.class.getName());
+			getLogger(JavaNetworkManager.class.getName());
 
 	@Inject
 	JavaNetworkManager() {
@@ -31,26 +33,28 @@ class JavaNetworkManager implements NetworkManager {
 
 	@Override
 	public NetworkStatus getNetworkStatus() {
-		boolean connected = false;
+		boolean connected = false, hasIpv4 = false, hasIpv6Unicast = false;
 		try {
 			Enumeration<NetworkInterface> interfaces = getNetworkInterfaces();
-			if (interfaces != null) {
+			if (interfaces == null) {
+				LOG.info("No network interfaces");
+			} else {
 				for (NetworkInterface i : list(interfaces)) {
-					if (i.isLoopback()) continue;
+					if (i.isLoopback() || !i.isUp()) continue;
-					if (i.isUp() && i.getInetAddresses().hasMoreElements()) {
+					for (InetAddress addr : list(i.getInetAddresses())) {
-						if (LOG.isLoggable(INFO)) {
-							LOG.info("Interface " + i.getDisplayName() +
-									" is up with at least one address.");
-						}
 						connected = true;
-						break;
+						if (addr instanceof Inet4Address) {
+							hasIpv4 = true;
+						} else if (!addr.isMulticastAddress()) {
+							hasIpv6Unicast = true;
+						}
 					}
 				}
 			}
 		} catch (SocketException e) {
 			logException(LOG, WARNING, e);
 		}
-		return new NetworkStatus(connected, false);
+		return new NetworkStatus(connected, false, !hasIpv4 && hasIpv6Unicast);
 	}
 
 }

bramble-java/witness.gradle

@@ -24,7 +24,7 @@ dependencyVerification {
         'org.apache.ant:ant:1.9.4:ant-1.9.4.jar:649ae0730251de07b8913f49286d46bba7b92d47c5f332610aa426c4f02161d8',
         'org.beanshell:bsh:1.3.0:bsh-1.3.0.jar:9b04edc75d19db54f1b4e8b5355e9364384c6cf71eb0a1b9724c159d779879f8',
         'org.briarproject:obfs4proxy:0.0.7:obfs4proxy-0.0.7.zip:5b2f693262ce43a7e130f7cc7d5d1617925330640a2eb6d71085e95df8ee0642',
-        'org.briarproject:tor:0.3.5.10:tor-0.3.5.10.zip:7b387d3523ae8af289c23be59dc4c64ec5d3721385d7825a09705095e3318d5c',
+        'org.briarproject:tor:0.3.5.12:tor-0.3.5.12.zip:2f542c4befd216f2226bf7c76e3b8b2d99af6f146a8cb28bf727f42014587006',
         'org.checkerframework:checker-compat-qual:2.5.3:checker-compat-qual-2.5.3.jar:d76b9afea61c7c082908023f0cbc1427fab9abd2df915c8b8a3e7a509bccbc6d',
         'org.checkerframework:checker-qual:2.5.2:checker-qual-2.5.2.jar:64b02691c8b9d4e7700f8ee2e742dce7ea2c6e81e662b7522c9ee3bf568c040a',
         'org.codehaus.mojo:animal-sniffer-annotations:1.17:animal-sniffer-annotations-1.17.jar:92654f493ecfec52082e76354f0ebf87648dc3d5cec2e3c3cdb947c016747a53',

briar-android/build.gradle

@@ -16,14 +16,14 @@ def getStdout = { command, defaultValue ->
 }
 
 android {
-	compileSdkVersion 29
+	compileSdkVersion rootProject.ext.compileSdkVersion
-	buildToolsVersion '29.0.2'
+	buildToolsVersion rootProject.ext.buildToolsVersion
 
 	defaultConfig {
-		minSdkVersion 16
+		minSdkVersion rootProject.ext.minSdkVersion
-		targetSdkVersion 28
+		targetSdkVersion rootProject.ext.targetSdkVersion
-		versionCode 10209
+		versionCode rootProject.ext.versionCode
-		versionName "1.2.9"
+		versionName rootProject.ext.versionName
 		applicationId "org.briarproject.briar.android"
 		buildConfigField "String", "GitHash",
 				"\"${getStdout(['git', 'rev-parse', '--short=7', 'HEAD'], 'No commit hash')}\""
@@ -93,20 +93,19 @@ dependencies {
 	implementation project(path: ':bramble-core', configuration: 'default')
 	implementation project(':bramble-android')
 
-	implementation 'androidx.preference:preference:1.1.0'
+	implementation 'androidx.preference:preference:1.1.1'
-	implementation 'androidx.exifinterface:exifinterface:1.0.0'
+	implementation 'androidx.exifinterface:exifinterface:1.3.1'
-	implementation 'androidx.lifecycle:lifecycle-extensions:2.1.0'
+	implementation 'androidx.lifecycle:lifecycle-extensions:2.2.0'
-	implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
+	implementation 'androidx.constraintlayout:constraintlayout:2.0.4'
-	implementation 'com.google.android.material:material:1.1.0-beta01'
+	implementation 'com.google.android.material:material:1.2.1'
-	implementation 'androidx.recyclerview:recyclerview-selection:1.1.0-rc01'
+	implementation 'androidx.recyclerview:recyclerview-selection:1.1.0-rc03'
 
-	implementation 'ch.acra:acra:4.11'
 	implementation 'info.guardianproject.panic:panic:1.0'
 	implementation 'info.guardianproject.trustedintents:trustedintents:0.2'
 	implementation 'de.hdodenhof:circleimageview:3.0.1'
 	implementation 'com.google.zxing:core:3.3.3'  // newer version need minSdk 24
 	implementation 'uk.co.samuelwall:material-tap-target-prompt:3.0.0'
-	implementation 'com.vanniktech:emoji-google:0.6.0'
+	implementation 'com.vanniktech:emoji-google:0.6.0' // newer versions need minSdk 21
 	implementation 'com.github.kobakei:MaterialFabSpeedDial:1.2.1'
 	implementation 'com.github.chrisbanes:PhotoView:2.3.0'
 	def glideVersion = '4.10.0'
@@ -120,23 +119,24 @@ dependencies {
 
 	compileOnly 'javax.annotation:jsr250-api:1.0'
 
-	def espressoVersion = '3.2.0'
+	def espressoVersion = '3.3.0'
 	def jmockVersion = '2.8.2'
 	testImplementation project(path: ':bramble-api', configuration: 'testOutput')
 	testImplementation project(path: ':bramble-core', configuration: 'testOutput')
-	testImplementation 'androidx.test:runner:1.2.0'
+	testImplementation 'androidx.test:runner:1.3.0'
-	testImplementation 'androidx.test.ext:junit:1.1.1'
+	testImplementation 'androidx.test.ext:junit:1.1.2'
-	testImplementation 'androidx.fragment:fragment-testing:1.1.0'
+	testImplementation 'androidx.fragment:fragment-testing:1.2.5'
+	testImplementation "androidx.arch.core:core-testing:2.1.0"
 	testImplementation "androidx.test.espresso:espresso-core:$espressoVersion"
 	testImplementation 'org.robolectric:robolectric:4.3.1'
 	testImplementation 'org.mockito:mockito-core:3.1.0'
-	testImplementation 'junit:junit:4.12'
+	testImplementation 'junit:junit:4.13.1'
 	testImplementation "org.jmock:jmock:$jmockVersion"
 	testImplementation "org.jmock:jmock-junit4:$jmockVersion"
 	testImplementation "org.jmock:jmock-legacy:$jmockVersion"
 
 	androidTestImplementation project(path: ':bramble-api', configuration: 'testOutput')
-	androidTestImplementation 'androidx.test.ext:junit:1.1.1'
+	androidTestImplementation 'androidx.test.ext:junit:1.1.2'
 	androidTestImplementation "androidx.test.espresso:espresso-core:$espressoVersion"
 	androidTestImplementation "androidx.test.espresso:espresso-contrib:$espressoVersion"
 	androidTestImplementation "androidx.test.espresso:espresso-intents:$espressoVersion"

briar-android/proguard-rules.txt

@@ -37,3 +37,6 @@
 
 # Glide
 -dontwarn com.bumptech.glide.load.engine.cache.DiskLruCacheWrapper
+
+# Dependency injection annotations, needed for UI tests on older API levels
+-keep class javax.inject.**

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);
+		AttachmentItem item = retriever.createAttachmentItem(a, true);
-		assertTrue(item.hasError());
+		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/AndroidManifest.xml

@@ -65,30 +65,43 @@
 
 		<service
 			android:name="org.briarproject.briar.android.NotificationCleanupService"
-			android:exported="false"></service>
+			android:exported="false" />
 
 		<activity
-			android:name="org.briarproject.briar.android.reporting.DevReportActivity"
+			android:name="org.briarproject.briar.android.reporting.CrashReportActivity"
 			android:excludeFromRecents="true"
 			android:exported="false"
 			android:finishOnTaskLaunch="true"
 			android:label="@string/crash_report_title"
 			android:launchMode="singleInstance"
+			android:process=":briar_error_handler"
 			android:theme="@style/BriarTheme.NoActionBar"
-			android:windowSoftInputMode="adjustResize|stateHidden"></activity>
+			android:windowSoftInputMode="adjustResize|stateHidden" />
+
+		<activity
+			android:name="org.briarproject.briar.android.reporting.FeedbackActivity"
+			android:exported="false"
+			android:label="@string/feedback_title"
+			android:parentActivityName="org.briarproject.briar.android.settings.SettingsActivity"
+			android:theme="@style/BriarTheme.NoActionBar"
+			android:windowSoftInputMode="adjustResize|stateHidden">
+			<meta-data
+				android:name="android.support.PARENT_ACTIVITY"
+				android:value="org.briarproject.briar.android.settings.SettingsActivity" />
+		</activity>
 
 		<activity
 			android:name="org.briarproject.briar.android.splash.ExpiredActivity"
-			android:label="@string/app_name"></activity>
+			android:label="@string/app_name" />
 
 		<activity
 			android:name="org.briarproject.briar.android.login.StartupActivity"
-			android:label="@string/app_name"></activity>
+			android:label="@string/app_name" />
 
 		<activity
 			android:name="org.briarproject.briar.android.account.SetupActivity"
 			android:label="@string/setup_title"
-			android:windowSoftInputMode="adjustResize|stateAlwaysVisible"></activity>
+			android:windowSoftInputMode="adjustResize|stateAlwaysVisible" />
 
 		<activity
 			android:name="org.briarproject.briar.android.splash.SplashScreenActivity"
@@ -346,7 +359,7 @@
 
 		<activity
 			android:name="org.briarproject.briar.android.StartupFailureActivity"
-			android:label="@string/startup_failed_activity_title"></activity>
+			android:label="@string/startup_failed_activity_title" />
 
 		<activity
 			android:name="org.briarproject.briar.android.settings.SettingsActivity"
@@ -412,11 +425,11 @@
 
 		<activity
 			android:name="org.briarproject.briar.android.logout.ExitActivity"
-			android:theme="@android:style/Theme.NoDisplay"></activity>
+			android:theme="@android:style/Theme.NoDisplay" />
 
 		<activity
 			android:name=".android.logout.HideUiActivity"
-			android:theme="@android:style/Theme.NoDisplay"></activity>
+			android:theme="@android:style/Theme.NoDisplay" />
 
 		<activity
 			android:name=".android.account.UnlockActivity"
@@ -436,4 +449,27 @@
 			android:theme="@style/BriarTheme" />
 
 	</application>
+
+	<queries>
+		<package android:name="info.guardianproject.ripple" />
+		<package android:name="com.huawei.systemmanager" />
+
+		<intent>
+			<action android:name="android.intent.action.VIEW" />
+			<data android:scheme="https" />
+		</intent>
+		<intent>
+			<action android:name="android.intent.action.VIEW" />
+			<data android:scheme="http" />
+		</intent>
+		<!-- white-listing the intents below does not seem necessary,
+		but they are still included in case modified Android versions require it -->
+		<intent>
+			<action android:name="android.bluetooth.adapter.action.REQUEST_DISCOVERABLE" />
+		</intent>
+		<intent>
+			<action android:name="android.settings.CHANNEL_NOTIFICATION_SETTINGS" />
+		</intent>
+	</queries>
+
 </manifest>

briar-android/src/main/java/org/briarproject/briar/android/AndroidComponent.java

@@ -14,6 +14,7 @@ import org.briarproject.bramble.api.contact.ContactManager;
 import org.briarproject.bramble.api.crypto.CryptoExecutor;
 import org.briarproject.bramble.api.crypto.PasswordStrengthEstimator;
 import org.briarproject.bramble.api.db.DatabaseExecutor;
+import org.briarproject.bramble.api.db.TransactionManager;
 import org.briarproject.bramble.api.event.EventBus;
 import org.briarproject.bramble.api.identity.IdentityManager;
 import org.briarproject.bramble.api.keyagreement.KeyAgreementTask;
@@ -33,7 +34,6 @@ import org.briarproject.briar.BriarCoreModule;
 import org.briarproject.briar.android.attachment.AttachmentModule;
 import org.briarproject.briar.android.conversation.glide.BriarModelLoader;
 import org.briarproject.briar.android.login.SignInReminderReceiver;
-import org.briarproject.briar.android.reporting.BriarReportSender;
 import org.briarproject.briar.android.view.EmojiTextInputView;
 import org.briarproject.briar.api.android.AndroidNotificationManager;
 import org.briarproject.briar.api.android.DozeWatchdog;
@@ -86,6 +86,8 @@ public interface AndroidComponent
 	@DatabaseExecutor
 	Executor databaseExecutor();
 
+	TransactionManager transactionManager();
+
 	MessageTracker messageTracker();
 
 	LifecycleManager lifecycleManager();
@@ -173,8 +175,6 @@ public interface AndroidComponent
 
 	void inject(BriarService briarService);
 
-	void inject(BriarReportSender briarReportSender);
-
 	void inject(NotificationCleanupService notificationCleanupService);
 
 	void inject(EmojiTextInputView textInputView);

briar-android/src/main/java/org/briarproject/briar/android/AndroidNotificationManagerImpl.java

@@ -109,7 +109,8 @@ class AndroidNotificationManagerImpl implements AndroidNotificationManager,
 	@Nullable
 	private GroupId blockedGroup = null;
 	private boolean blockSignInReminder = false;
-	private boolean blockBlogs = false;
+	private boolean blockForums = false, blockGroups = false,
+			blockBlogs = false;
 	private long lastSound = 0;
 
 	private volatile Settings settings = new Settings();
@@ -223,8 +224,8 @@ class AndroidNotificationManagerImpl implements AndroidNotificationManager,
 			if (s.getNamespace().equals(SETTINGS_NAMESPACE))
 				settings = s.getSettings();
 		} else if (e instanceof ConversationMessageReceivedEvent) {
-			ConversationMessageReceivedEvent p =
+			ConversationMessageReceivedEvent<?> p =
-					(ConversationMessageReceivedEvent) e;
+					(ConversationMessageReceivedEvent<?>) e;
 			showContactNotification(p.getContactId());
 		} else if (e instanceof GroupMessageAddedEvent) {
 			GroupMessageAddedEvent g = (GroupMessageAddedEvent) e;
@@ -385,6 +386,7 @@ class AndroidNotificationManagerImpl implements AndroidNotificationManager,
 
 	@UiThread
 	private void showGroupMessageNotification(GroupId g) {
+		if (blockGroups) return;
 		if (g.equals(blockedGroup)) return;
 		groupCounts.add(g);
 		updateGroupMessageNotification(true);
@@ -452,6 +454,7 @@ class AndroidNotificationManagerImpl implements AndroidNotificationManager,
 
 	@UiThread
 	private void showForumPostNotification(GroupId g) {
+		if (blockForums) return;
 		if (g.equals(blockedGroup)) return;
 		forumCounts.add(g);
 		updateForumPostNotification(true);
@@ -681,6 +684,26 @@ class AndroidNotificationManagerImpl implements AndroidNotificationManager,
 		});
 	}
 
+	@Override
+	public void blockAllForumPostNotifications() {
+		androidExecutor.runOnUiThread((Runnable) () -> blockForums = true);
+	}
+
+	@Override
+	public void unblockAllForumPostNotifications() {
+		androidExecutor.runOnUiThread((Runnable) () -> blockForums = false);
+	}
+
+	@Override
+	public void blockAllGroupMessageNotifications() {
+		androidExecutor.runOnUiThread((Runnable) () -> blockGroups = true);
+	}
+
+	@Override
+	public void unblockAllGroupMessageNotifications() {
+		androidExecutor.runOnUiThread((Runnable) () -> blockGroups = false);
+	}
+
 	@Override
 	public void blockAllBlogPostNotifications() {
 		androidExecutor.runOnUiThread((Runnable) () -> blockBlogs = true);

briar-android/src/main/java/org/briarproject/briar/android/AppModule.java

@@ -28,9 +28,12 @@ import org.briarproject.bramble.plugin.tor.AndroidTorPluginFactory;
 import org.briarproject.bramble.util.AndroidUtils;
 import org.briarproject.bramble.util.StringUtils;
 import org.briarproject.briar.android.account.LockManagerImpl;
+import org.briarproject.briar.android.forum.ForumModule;
 import org.briarproject.briar.android.keyagreement.ContactExchangeModule;
 import org.briarproject.briar.android.login.LoginModule;
 import org.briarproject.briar.android.navdrawer.NavDrawerModule;
+import org.briarproject.briar.android.privategroup.list.GroupListModule;
+import org.briarproject.briar.android.reporting.DevReportModule;
 import org.briarproject.briar.android.viewmodel.ViewModelModule;
 import org.briarproject.briar.api.android.AndroidNotificationManager;
 import org.briarproject.briar.api.android.DozeWatchdog;
@@ -63,7 +66,11 @@ import static org.briarproject.briar.android.TestingConstants.IS_DEBUG_BUILD;
 		ContactExchangeModule.class,
 		LoginModule.class,
 		NavDrawerModule.class,
-		ViewModelModule.class
+		ViewModelModule.class,
+		DevReportModule.class,
+		// below need to be within same scope as ViewModelProvider.Factory
+		ForumModule.BindsModule.class,
+		GroupListModule.class,
 })
 public class AppModule {
 
@@ -196,7 +203,10 @@ public class AppModule {
 	ScreenFilterMonitor provideScreenFilterMonitor(
 			LifecycleManager lifecycleManager,
 			ScreenFilterMonitorImpl screenFilterMonitor) {
-		lifecycleManager.registerService(screenFilterMonitor);
+		if (SDK_INT <= 29) {
+			// this keeps track of installed apps and does not work on API 30+
+			lifecycleManager.registerService(screenFilterMonitor);
+		}
 		return screenFilterMonitor;
 	}
 

briar-android/src/main/java/org/briarproject/briar/android/BriarApplicationImpl.java

@@ -14,19 +14,13 @@ import android.preference.PreferenceManager;
 import com.vanniktech.emoji.EmojiManager;
 import com.vanniktech.emoji.google.GoogleEmojiProvider;
 
-import org.acra.ACRA;
-import org.acra.ReportingInteractionMode;
-import org.acra.annotation.ReportsCrashes;
 import org.briarproject.bramble.BrambleAndroidEagerSingletons;
 import org.briarproject.bramble.BrambleAppComponent;
 import org.briarproject.bramble.BrambleCoreEagerSingletons;
 import org.briarproject.briar.BriarCoreEagerSingletons;
-import org.briarproject.briar.BuildConfig;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.logging.CachingLogHandler;
-import org.briarproject.briar.android.reporting.BriarReportPrimer;
+import org.briarproject.briar.android.reporting.BriarExceptionHandler;
-import org.briarproject.briar.android.reporting.BriarReportSenderFactory;
-import org.briarproject.briar.android.reporting.DevReportActivity;
 import org.briarproject.briar.android.util.UiUtils;
 
 import java.util.Collection;
@@ -34,50 +28,14 @@ import java.util.logging.Handler;
 import java.util.logging.LogRecord;
 import java.util.logging.Logger;
 
+import androidx.annotation.NonNull;
+
 import static android.app.ActivityManager.RunningAppProcessInfo.IMPORTANCE_FOREGROUND;
 import static java.util.logging.Level.FINE;
 import static java.util.logging.Level.INFO;
 import static java.util.logging.Logger.getLogger;
-import static org.acra.ReportField.ANDROID_VERSION;
-import static org.acra.ReportField.APP_VERSION_CODE;
-import static org.acra.ReportField.APP_VERSION_NAME;
-import static org.acra.ReportField.BRAND;
-import static org.acra.ReportField.BUILD_CONFIG;
-import static org.acra.ReportField.CRASH_CONFIGURATION;
-import static org.acra.ReportField.CUSTOM_DATA;
-import static org.acra.ReportField.DEVICE_FEATURES;
-import static org.acra.ReportField.DISPLAY;
-import static org.acra.ReportField.INITIAL_CONFIGURATION;
-import static org.acra.ReportField.PACKAGE_NAME;
-import static org.acra.ReportField.PHONE_MODEL;
-import static org.acra.ReportField.PRODUCT;
-import static org.acra.ReportField.REPORT_ID;
-import static org.acra.ReportField.STACK_TRACE;
-import static org.acra.ReportField.USER_APP_START_DATE;
-import static org.acra.ReportField.USER_CRASH_DATE;
 import static org.briarproject.briar.android.TestingConstants.IS_DEBUG_BUILD;
 
-@ReportsCrashes(
-		reportPrimerClass = BriarReportPrimer.class,
-		logcatArguments = {"-d", "-v", "time", "*:I"},
-		reportSenderFactoryClasses = {BriarReportSenderFactory.class},
-		mode = ReportingInteractionMode.DIALOG,
-		reportDialogClass = DevReportActivity.class,
-		resDialogOkToast = R.string.dev_report_saved,
-		deleteOldUnsentReportsOnApplicationStart = false,
-		buildConfigClass = BuildConfig.class,
-		customReportContent = {
-				REPORT_ID,
-				APP_VERSION_CODE, APP_VERSION_NAME, PACKAGE_NAME,
-				PHONE_MODEL, ANDROID_VERSION, BRAND, PRODUCT,
-				BUILD_CONFIG,
-				CUSTOM_DATA,
-				STACK_TRACE,
-				INITIAL_CONFIGURATION, CRASH_CONFIGURATION,
-				DISPLAY, DEVICE_FEATURES,
-				USER_APP_START_DATE, USER_CRASH_DATE
-		}
-)
 public class BriarApplicationImpl extends Application
 		implements BriarApplication {
 
@@ -85,12 +43,15 @@ public class BriarApplicationImpl extends Application
 			getLogger(BriarApplicationImpl.class.getName());
 
 	private final CachingLogHandler logHandler = new CachingLogHandler();
+	private final BriarExceptionHandler exceptionHandler =
+			new BriarExceptionHandler(this);
 
 	private AndroidComponent applicationComponent;
 	private volatile SharedPreferences prefs;
 
 	@Override
 	protected void attachBaseContext(Context base) {
+		Thread.setDefaultUncaughtExceptionHandler(exceptionHandler);
 		if (prefs == null)
 			prefs = PreferenceManager.getDefaultSharedPreferences(base);
 		// Loading the language needs to be done here.
@@ -98,7 +59,6 @@ public class BriarApplicationImpl extends Application
 		super.attachBaseContext(
 				Localizer.getInstance().setLocale(base));
 		setTheme(base, prefs);
-		ACRA.init(this);
 	}
 
 	@Override
@@ -144,7 +104,7 @@ public class BriarApplicationImpl extends Application
 	}
 
 	@Override
-	public void onConfigurationChanged(Configuration newConfig) {
+	public void onConfigurationChanged(@NonNull Configuration newConfig) {
 		super.onConfigurationChanged(newConfig);
 		Localizer.getInstance().setLocale(this);
 	}

briar-android/src/main/java/org/briarproject/briar/android/ScreenFilterMonitorImpl.java

@@ -58,7 +58,7 @@ class ScreenFilterMonitorImpl implements ScreenFilterMonitor, Service {
 			Logger.getLogger(ScreenFilterMonitorImpl.class.getName());
 
 	/*
- 	 * Ignore Play Services if it uses this package name and public key - it's
+	 * Ignore Play Services if it uses this package name and public key - it's
 	 * effectively a system app, but not flagged as such on older systems
 	 */
 	private static final String PLAY_SERVICES_PACKAGE =
@@ -108,7 +108,7 @@ class ScreenFilterMonitorImpl implements ScreenFilterMonitor, Service {
 		Set<String> allowed = prefs.getStringSet(PREF_KEY_ALLOWED,
 				Collections.emptySet());
 		List<AppDetails> apps = new ArrayList<>();
-		List<PackageInfo> packageInfos =
+		@SuppressLint("QueryPermissionsNeeded") List<PackageInfo> packageInfos =
 				pm.getInstalledPackages(GET_PERMISSIONS);
 		for (PackageInfo packageInfo : packageInfos) {
 			if (!allowed.contains(packageInfo.packageName)

briar-android/src/main/java/org/briarproject/briar/android/account/AuthorNameFragment.java

@@ -17,7 +17,6 @@ import org.briarproject.briar.android.activity.ActivityComponent;
 
 import javax.annotation.Nullable;
 
-import static java.util.Objects.requireNonNull;
 import static org.briarproject.bramble.api.identity.AuthorConstants.MAX_AUTHOR_NAME_LENGTH;
 import static org.briarproject.bramble.util.StringUtils.toUtf8;
 import static org.briarproject.briar.android.util.UiUtils.setError;
@@ -45,7 +44,7 @@ public class AuthorNameFragment extends SetupFragment {
 	public View onCreateView(LayoutInflater inflater,
 			@Nullable ViewGroup container,
 			@Nullable Bundle savedInstanceState) {
-		requireNonNull(getActivity()).setTitle(getString(R.string.setup_title));
+		requireActivity().setTitle(getString(R.string.setup_title));
 		View v = inflater.inflate(R.layout.fragment_setup_author_name,
 				container, false);
 		authorNameWrapper = v.findViewById(R.id.nickname_entry_wrapper);

briar-android/src/main/java/org/briarproject/briar/android/account/DozeFragment.java

@@ -20,7 +20,6 @@ import androidx.annotation.Nullable;
 
 import static android.view.View.INVISIBLE;
 import static android.view.View.VISIBLE;
-import static java.util.Objects.requireNonNull;
 import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_DOZE_WHITELISTING;
 import static org.briarproject.briar.android.util.UiUtils.showOnboardingDialog;
 
@@ -50,10 +49,10 @@ public class DozeFragment extends SetupFragment
 	public View onCreateView(LayoutInflater inflater,
 			@Nullable ViewGroup container,
 			@Nullable Bundle savedInstanceState) {
-		requireNonNull(getActivity()).setTitle(getString(R.string.setup_doze_title));
+		requireActivity().setTitle(getString(R.string.setup_doze_title));
 		setHasOptionsMenu(false);
 		View v = inflater.inflate(R.layout.fragment_setup_doze, container,
-						false);
+				false);
 		dozeView = v.findViewById(R.id.dozeView);
 		dozeView.setOnCheckedChangedListener(this);
 		huaweiView = v.findViewById(R.id.huaweiView);
@@ -78,7 +77,8 @@ public class DozeFragment extends SetupFragment
 	}
 
 	@Override
-	public void onActivityResult(int request, int result, Intent data) {
+	public void onActivityResult(int request, int result,
+			@Nullable Intent data) {
 		super.onActivityResult(request, result, data);
 		if (request == REQUEST_DOZE_WHITELISTING) {
 			if (!dozeView.needsToBeShown() || secondAttempt) {
@@ -92,11 +92,7 @@ public class DozeFragment extends SetupFragment
 
 	@Override
 	public void onCheckedChanged() {
-		if (dozeView.isChecked() && huaweiView.isChecked()) {
+		next.setEnabled(dozeView.isChecked() && huaweiView.isChecked());
-			next.setEnabled(true);
-		} else {
-			next.setEnabled(false);
-		}
 	}
 
 	@SuppressLint("BatteryLife")

briar-android/src/main/java/org/briarproject/briar/android/account/SetPasswordFragment.java

@@ -24,7 +24,6 @@ import static android.content.Context.INPUT_METHOD_SERVICE;
 import static android.view.View.INVISIBLE;
 import static android.view.View.VISIBLE;
 import static android.view.inputmethod.EditorInfo.IME_ACTION_DONE;
-import static java.util.Objects.requireNonNull;
 import static org.briarproject.bramble.api.crypto.PasswordStrengthEstimator.QUITE_WEAK;
 import static org.briarproject.briar.android.util.UiUtils.setError;
 
@@ -55,7 +54,7 @@ public class SetPasswordFragment extends SetupFragment {
 	public View onCreateView(LayoutInflater inflater,
 			@Nullable ViewGroup container,
 			@Nullable Bundle savedInstanceState) {
-		requireNonNull(getActivity()).setTitle(getString(R.string.setup_password_intro));
+		requireActivity().setTitle(getString(R.string.setup_password_intro));
 		View v = inflater.inflate(R.layout.fragment_setup_password, container,
 						false);
 

briar-android/src/main/java/org/briarproject/briar/android/activity/ActivityComponent.java

@@ -60,12 +60,14 @@ import org.briarproject.briar.android.privategroup.creation.GroupInviteFragment;
 import org.briarproject.briar.android.privategroup.invitation.GroupInvitationActivity;
 import org.briarproject.briar.android.privategroup.invitation.GroupInvitationModule;
 import org.briarproject.briar.android.privategroup.list.GroupListFragment;
-import org.briarproject.briar.android.privategroup.list.GroupListModule;
 import org.briarproject.briar.android.privategroup.memberlist.GroupMemberListActivity;
 import org.briarproject.briar.android.privategroup.memberlist.GroupMemberModule;
 import org.briarproject.briar.android.privategroup.reveal.GroupRevealModule;
 import org.briarproject.briar.android.privategroup.reveal.RevealContactsActivity;
 import org.briarproject.briar.android.privategroup.reveal.RevealContactsFragment;
+import org.briarproject.briar.android.reporting.CrashFragment;
+import org.briarproject.briar.android.reporting.CrashReportActivity;
+import org.briarproject.briar.android.reporting.ReportFormFragment;
 import org.briarproject.briar.android.settings.SettingsActivity;
 import org.briarproject.briar.android.settings.SettingsFragment;
 import org.briarproject.briar.android.sharing.BlogInvitationActivity;
@@ -91,7 +93,6 @@ import dagger.Component;
 		ForumModule.class,
 		GroupInvitationModule.class,
 		GroupConversationModule.class,
-		GroupListModule.class,
 		GroupMemberModule.class,
 		GroupRevealModule.class,
 		SharingModule.class
@@ -184,6 +185,8 @@ public interface ActivityComponent {
 
 	void inject(PendingContactListActivity activity);
 
+	void inject(CrashReportActivity crashReportActivity);
+
 	// Fragments
 
 	void inject(AuthorNameFragment fragment);
@@ -234,4 +237,8 @@ public interface ActivityComponent {
 
 	void inject(ImageFragment imageFragment);
 
+	void inject(ReportFormFragment reportFormFragment);
+
+	void inject(CrashFragment crashFragment);
+
 }

briar-android/src/main/java/org/briarproject/briar/android/activity/BaseActivity.java

@@ -6,7 +6,6 @@ import android.view.View;
 import android.view.ViewGroup;
 import android.view.ViewGroup.LayoutParams;
 
-import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.briar.R;
@@ -18,7 +17,6 @@ import org.briarproject.briar.android.controller.ActivityLifecycleController;
 import org.briarproject.briar.android.forum.ForumModule;
 import org.briarproject.briar.android.fragment.BaseFragment;
 import org.briarproject.briar.android.fragment.ScreenFilterDialogFragment;
-import org.briarproject.briar.android.reporting.DevReportActivity;
 import org.briarproject.briar.android.util.UiUtils;
 import org.briarproject.briar.android.widget.TapSafeFrameLayout;
 import org.briarproject.briar.android.widget.TapSafeFrameLayout.OnTapFilteredListener;
@@ -40,9 +38,11 @@ import androidx.appcompat.widget.Toolbar;
 import androidx.fragment.app.Fragment;
 import androidx.fragment.app.FragmentManager;
 
+import static android.os.Build.VERSION.SDK_INT;
 import static android.view.ViewGroup.LayoutParams.MATCH_PARENT;
 import static android.view.WindowManager.LayoutParams.FLAG_SECURE;
 import static androidx.lifecycle.Lifecycle.State.STARTED;
+import static java.util.Collections.emptyList;
 import static java.util.logging.Level.INFO;
 import static java.util.logging.Logger.getLogger;
 import static org.briarproject.briar.android.TestingConstants.PREVENT_SCREENSHOTS;
@@ -50,7 +50,6 @@ import static org.briarproject.briar.android.util.UiUtils.hideSoftKeyboard;
 
 /**
  * Warning: Some activities don't extend {@link BaseActivity}.
- *          E.g. {@link DevReportActivity}
  */
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
@@ -123,6 +122,7 @@ public abstract class BaseActivity extends AppCompatActivity
 		return new ActivityModule(this);
 	}
 
+	// TODO use a test module where this is used in tests
 	protected ForumModule getForumModule() {
 		return new ForumModule();
 	}
@@ -202,9 +202,15 @@ public abstract class BaseActivity extends AppCompatActivity
 		// If the dialog is already visible, filter the tap
 		ScreenFilterDialogFragment f = findDialogFragment();
 		if (f != null && f.isVisible()) return false;
-		Collection<AppDetails> apps = screenFilterMonitor.getApps();
+		Collection<AppDetails> apps;
-		// If all overlay apps have been allowed, allow the tap
+		// querying all apps is only possible at API 29 and below
-		if (apps.isEmpty()) return true;
+		if (SDK_INT <= 29) {
+			apps = screenFilterMonitor.getApps();
+			// If all overlay apps have been allowed, allow the tap
+			if (apps.isEmpty()) return true;
+		} else {
+			apps = emptyList();
+		}
 		// Show dialog unless onSaveInstanceState() has been called, see #1112
 		FragmentManager fm = getSupportFragmentManager();
 		if (!fm.isStateSaved()) {
@@ -241,7 +247,7 @@ public abstract class BaseActivity extends AppCompatActivity
 	}
 
 	@UiThread
-	public void handleDbException(DbException e) {
+	public void handleException(Exception e) {
 		supportFinishAfterTransition();
 	}
 
@@ -266,7 +272,12 @@ public abstract class BaseActivity extends AppCompatActivity
 	private void protectToolbar() {
 		findToolbar();
 		if (toolbar != null) {
-			boolean filter = !screenFilterMonitor.getApps().isEmpty();
+			boolean filter;
+			if (SDK_INT <= 29) {
+				filter = !screenFilterMonitor.getApps().isEmpty();
+			} else {
+				filter = true;
+			}
 			UiUtils.setFilterTouchesWhenObscured(toolbar, filter);
 		}
 	}

briar-android/src/main/java/org/briarproject/briar/android/activity/BriarActivity.java

@@ -129,10 +129,6 @@ public abstract class BriarActivity extends BaseActivity {
 		lockManager.onActivityStop();
 	}
 
-	protected boolean signedIn() {
-		return briarController.accountSignedIn();
-	}
-
 	/**
 	 * Sets the transition animations.
 	 *

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);
+			AttachmentItem item = retriever.createAttachmentItem(a, needsSize);
-			if (item.hasError()) throw new IOException();
+			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();
+		if (task != null) task.cancel();
-		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 State state;
-	private final long instanceId;
 
 	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;
+		this.state = state;
-		instanceId = NEXT_INSTANCE_ID.getAndIncrement();
+	}
+
+	/**
+	 * 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;
+		state = State.valueOf(requireNonNull(in.readString()));
-		instanceId = in.readLong();
 		header = new AttachmentHeader(messageId, mimeType);
 	}
 
@@ -101,12 +123,16 @@ public class AttachmentItem implements Parcelable {
 		return thumbnailHeight;
 	}
 
-	public boolean hasError() {
+	public State getState() {
-		return hasError;
+		return state;
 	}
 
-	public String getTransitionName() {
+	public String getTransitionName(MessageId conversationItemId) {
-		return String.valueOf(instanceId);
+		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.writeString(state.name());
-		dest.writeLong(instanceId);
 	}
 
+	/**
+	 * 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);
+	@DatabaseExecutor
-
-	@Nullable
-	List<AttachmentItem> cacheGet(MessageId messageId);
-
 	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 =
+	private final ConcurrentMap<MessageId, MutableLiveData<AttachmentItem>>
-			new ConcurrentHashMap<>();
+			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,
+	@DatabaseExecutor
-			List<AttachmentItem> attachments) {
-		attachmentCache.put(messageId, attachments);
-	}
-
-	@Override
-	@Nullable
-	public List<AttachmentItem> cacheGet(MessageId messageId) {
-		return attachmentCache.get(messageId);
-	}
-
-	@Override
 	public Attachment getMessageAttachment(AttachmentHeader h)
 			throws DbException {
 		return messagingManager.getAttachment(h);
 	}
 
 	@Override
-	public AttachmentItem getAttachmentItem(Attachment a, boolean needsSize) {
+	public List<LiveData<AttachmentItem>> getAttachmentItems(
-		AttachmentHeader h = a.getHeader();
+			PrivateMessageHeader messageHeader) {
-		if (!needsSize) {
+		List<AttachmentHeader> headers = messageHeader.getAttachmentHeaders();
-			String extension =
+		List<LiveData<AttachmentItem>> items = new ArrayList<>(headers.size());
-					imageHelper.getExtensionFromMimeType(h.getContentType());
+		boolean needsSize = headers.size() == 1;
-			boolean hasError = false;
+		for (AttachmentHeader h : headers) {
-			if (extension == null) {
+			// try cache for existing item live data
-				extension = "";
+			MutableLiveData<AttachmentItem> liveData;
-				hasError = true;
+			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());
+		// If no LiveData for the attachment exists,
-		Size size = imageSizeCalculator.getSize(is, h.getContentType());
+		// 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,
+		State state = hasError ? ERROR : AVAILABLE;
-				thumbnailSize.width, thumbnailSize.height, hasError);
+		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/blog/BasePostFragment.java

@@ -25,7 +25,6 @@ import androidx.annotation.UiThread;
 import static android.content.Intent.FLAG_ACTIVITY_CLEAR_TOP;
 import static android.view.View.INVISIBLE;
 import static android.view.View.VISIBLE;
-import static java.util.Objects.requireNonNull;
 import static java.util.logging.Logger.getLogger;
 import static org.briarproject.briar.android.activity.BriarActivity.GROUP_ID;
 import static org.briarproject.briar.android.util.UiUtils.MIN_DATE_RESOLUTION;
@@ -55,7 +54,7 @@ abstract class BasePostFragment extends BaseFragment {
 			@Nullable ViewGroup container,
 			@Nullable Bundle savedInstanceState) {
 		// retrieve MessageId of blog post from arguments
-		byte[] p = requireNonNull(getArguments()).getByteArray(POST_ID);
+		byte[] p = requireArguments().getByteArray(POST_ID);
 		if (p == null) throw new IllegalStateException("No post ID in args");
 		postId = new MessageId(p);
 

briar-android/src/main/java/org/briarproject/briar/android/blog/BlogFragment.java

@@ -46,7 +46,6 @@ import static android.app.Activity.RESULT_OK;
 import static android.content.Intent.FLAG_ACTIVITY_CLEAR_TOP;
 import static android.widget.Toast.LENGTH_SHORT;
 import static com.google.android.material.snackbar.Snackbar.LENGTH_LONG;
-import static java.util.Objects.requireNonNull;
 import static org.briarproject.briar.android.activity.BriarActivity.GROUP_ID;
 import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_SHARE_BLOG;
 import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_WRITE_BLOG_POST;
@@ -97,14 +96,14 @@ public class BlogFragment extends BaseFragment
 	public View onCreateView(LayoutInflater inflater,
 			@Nullable ViewGroup container,
 			@Nullable Bundle savedInstanceState) {
-		Bundle args = requireNonNull(getArguments());
+		Bundle args = requireArguments();
 		byte[] b = args.getByteArray(GROUP_ID);
 		if (b == null) throw new IllegalStateException("No group ID in args");
 		groupId = new GroupId(b);
 
 		View v = inflater.inflate(R.layout.fragment_blog, container, false);
 
-		adapter = new BlogPostAdapter(requireNonNull(getActivity()), this,
+		adapter = new BlogPostAdapter(requireActivity(), this,
 				getFragmentManager());
 		list = v.findViewById(R.id.postList);
 		layoutManager = new LinearLayoutManager(getActivity());
@@ -196,7 +195,8 @@ public class BlogFragment extends BaseFragment
 	}
 
 	@Override
-	public void onActivityResult(int request, int result, Intent data) {
+	public void onActivityResult(int request, int result,
+			@Nullable Intent data) {
 		super.onActivityResult(request, result, data);
 
 		if (request == REQUEST_WRITE_BLOG_POST && result == RESULT_OK) {
@@ -232,7 +232,7 @@ public class BlogFragment extends BaseFragment
 
 					@Override
 					public void onExceptionUi(DbException exception) {
-						handleDbException(exception);
+						handleException(exception);
 					}
 				}
 		);
@@ -277,7 +277,7 @@ public class BlogFragment extends BaseFragment
 
 					@Override
 					public void onExceptionUi(DbException exception) {
-						handleDbException(exception);
+						handleException(exception);
 					}
 				});
 	}
@@ -296,7 +296,7 @@ public class BlogFragment extends BaseFragment
 
 					@Override
 					public void onExceptionUi(DbException exception) {
-						handleDbException(exception);
+						handleException(exception);
 					}
 				});
 	}
@@ -318,7 +318,7 @@ public class BlogFragment extends BaseFragment
 
 					@Override
 					public void onExceptionUi(DbException exception) {
-						handleDbException(exception);
+						handleException(exception);
 					}
 				});
 	}
@@ -398,7 +398,7 @@ public class BlogFragment extends BaseFragment
 
 					@Override
 					public void onExceptionUi(DbException exception) {
-						handleDbException(exception);
+						handleException(exception);
 					}
 				});
 	}

briar-android/src/main/java/org/briarproject/briar/android/blog/BlogPostFragment.java

@@ -58,7 +58,7 @@ public class BlogPostFragment extends BasePostFragment implements BlogListener {
 
 					@Override
 					public void onExceptionUi(DbException exception) {
-						handleDbException(exception);
+						handleException(exception);
 					}
 				});
 	}

briar-android/src/main/java/org/briarproject/briar/android/blog/FeedFragment.java

@@ -35,7 +35,6 @@ import androidx.recyclerview.widget.LinearLayoutManager;
 import static android.app.Activity.RESULT_OK;
 import static android.content.Intent.FLAG_ACTIVITY_CLEAR_TOP;
 import static com.google.android.material.snackbar.Snackbar.LENGTH_LONG;
-import static java.util.Objects.requireNonNull;
 import static org.briarproject.briar.android.activity.BriarActivity.GROUP_ID;
 import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_WRITE_BLOG_POST;
 
@@ -79,7 +78,7 @@ public class FeedFragment extends BaseFragment implements
 	public View onCreateView(LayoutInflater inflater,
 			@Nullable ViewGroup container,
 			@Nullable Bundle savedInstanceState) {
-		requireNonNull(getActivity()).setTitle(R.string.blogs_button);
+		requireActivity().setTitle(R.string.blogs_button);
 
 		View v = inflater.inflate(R.layout.fragment_blog, container, false);
 
@@ -103,7 +102,8 @@ public class FeedFragment extends BaseFragment implements
 	}
 
 	@Override
-	public void onActivityResult(int requestCode, int resultCode, Intent data) {
+	public void onActivityResult(int requestCode, int resultCode,
+			@Nullable Intent data) {
 		super.onActivityResult(requestCode, resultCode, data);
 
 		// The BlogPostAddedEvent arrives when the controller is not listening
@@ -156,7 +156,7 @@ public class FeedFragment extends BaseFragment implements
 
 					@Override
 					public void onExceptionUi(DbException exception) {
-						handleDbException(exception);
+						handleException(exception);
 					}
 				});
 	}
@@ -187,7 +187,7 @@ public class FeedFragment extends BaseFragment implements
 
 					@Override
 					public void onExceptionUi(DbException exception) {
-						handleDbException(exception);
+						handleException(exception);
 					}
 				});
 	}
@@ -242,7 +242,7 @@ public class FeedFragment extends BaseFragment implements
 
 					@Override
 					public void onExceptionUi(DbException exception) {
-						handleDbException(exception);
+						handleException(exception);
 					}
 				}
 		);

briar-android/src/main/java/org/briarproject/briar/android/blog/FeedPostFragment.java

@@ -18,7 +18,6 @@ import javax.inject.Inject;
 
 import androidx.annotation.UiThread;
 
-import static java.util.Objects.requireNonNull;
 import static org.briarproject.briar.android.activity.BriarActivity.GROUP_ID;
 
 @UiThread
@@ -54,7 +53,7 @@ public class FeedPostFragment extends BasePostFragment {
 	public View onCreateView(LayoutInflater inflater,
 			@Nullable ViewGroup container,
 			@Nullable Bundle savedInstanceState) {
-		Bundle args = requireNonNull(getArguments());
+		Bundle args = requireArguments();
 		byte[] b = args.getByteArray(GROUP_ID);
 		if (b == null) throw new IllegalStateException("No group ID in args");
 		blogId = new GroupId(b);
@@ -80,7 +79,7 @@ public class FeedPostFragment extends BasePostFragment {
 
 					@Override
 					public void onExceptionUi(DbException exception) {
-						handleDbException(exception);
+						handleException(exception);
 					}
 				});
 	}

briar-android/src/main/java/org/briarproject/briar/android/blog/ReblogFragment.java

@@ -74,7 +74,7 @@ public class ReblogFragment extends BaseFragment implements SendListener {
 			@Nullable ViewGroup container,
 			@Nullable Bundle savedInstanceState) {
 
-		Bundle args = requireNonNull(getArguments());
+		Bundle args = requireArguments();
 		GroupId blogId =
 				new GroupId(requireNonNull(args.getByteArray(GROUP_ID)));
 		MessageId postId =
@@ -101,7 +101,7 @@ public class ReblogFragment extends BaseFragment implements SendListener {
 
 					@Override
 					public void onExceptionUi(DbException exception) {
-						handleDbException(exception);
+						handleException(exception);
 					}
 				});
 
@@ -128,7 +128,7 @@ public class ReblogFragment extends BaseFragment implements SendListener {
 				new UiExceptionHandler<DbException>(this) {
 					@Override
 					public void onExceptionUi(DbException exception) {
-						handleDbException(exception);
+						handleException(exception);
 					}
 				});
 		finish();

briar-android/src/main/java/org/briarproject/briar/android/contact/ContactListFragment.java

@@ -62,7 +62,6 @@ import static android.os.Build.VERSION.SDK_INT;
 import static androidx.core.app.ActivityOptionsCompat.makeSceneTransitionAnimation;
 import static androidx.core.view.ViewCompat.getTransitionName;
 import static com.google.android.material.snackbar.BaseTransientBottomBar.LENGTH_INDEFINITE;
-import static java.util.Objects.requireNonNull;
 import static java.util.logging.Level.WARNING;
 import static org.briarproject.bramble.util.LogUtils.logDuration;
 import static org.briarproject.bramble.util.LogUtils.logException;
@@ -122,7 +121,7 @@ public class ContactListFragment extends BaseFragment implements EventListener,
 	public View onCreateView(LayoutInflater inflater,
 			@Nullable ViewGroup container,
 			@Nullable Bundle savedInstanceState) {
-		requireNonNull(getActivity()).setTitle(R.string.contact_list_button);
+		requireActivity().setTitle(R.string.contact_list_button);
 
 		View contentView = inflater.inflate(R.layout.fragment_contact_list,
 				container, false);
@@ -274,8 +273,8 @@ public class ContactListFragment extends BaseFragment implements EventListener,
 			removeItem(((ContactRemovedEvent) e).getContactId());
 		} else if (e instanceof ConversationMessageReceivedEvent) {
 			LOG.info("Conversation message received, updating item");
-			ConversationMessageReceivedEvent p =
+			ConversationMessageReceivedEvent<?> p =
-					(ConversationMessageReceivedEvent) e;
+					(ConversationMessageReceivedEvent<?>) e;
 			ConversationMessageHeader h = p.getMessageHeader();
 			updateItem(p.getContactId(), h);
 		} else if (e instanceof PendingContactAddedEvent ||
@@ -317,7 +316,7 @@ public class ContactListFragment extends BaseFragment implements EventListener,
 	@UiThread
 	private void showSnackBar() {
 		if (snackbar != null) return;
-		View v = requireNonNull(getView());
+		View v = requireView();
 		int stringRes = R.string.pending_contact_requests_snackbar;
 		snackbar = new BriarSnackbarBuilder()
 				.setAction(R.string.show, view -> showPendingContactList())

briar-android/src/main/java/org/briarproject/briar/android/contact/add/remote/AddContactViewModel.java

@@ -9,7 +9,11 @@ import org.briarproject.bramble.api.contact.PendingContact;
 import org.briarproject.bramble.api.db.DatabaseExecutor;
 import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.db.NoSuchPendingContactException;
+import org.briarproject.bramble.api.db.TransactionManager;
+import org.briarproject.bramble.api.lifecycle.LifecycleManager;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.system.AndroidExecutor;
+import org.briarproject.briar.android.viewmodel.DbViewModel;
 import org.briarproject.briar.android.viewmodel.LiveEvent;
 import org.briarproject.briar.android.viewmodel.LiveResult;
 import org.briarproject.briar.android.viewmodel.MutableLiveEvent;
@@ -21,7 +25,6 @@ import java.util.logging.Logger;
 import javax.inject.Inject;
 
 import androidx.annotation.Nullable;
-import androidx.lifecycle.AndroidViewModel;
 import androidx.lifecycle.LiveData;
 import androidx.lifecycle.MutableLiveData;
 
@@ -31,14 +34,12 @@ import static org.briarproject.bramble.api.contact.HandshakeLinkConstants.LINK_R
 import static org.briarproject.bramble.util.LogUtils.logException;
 
 @NotNullByDefault
-public class AddContactViewModel extends AndroidViewModel {
+public class AddContactViewModel extends DbViewModel {
 
 	private final static Logger LOG =
 			getLogger(AddContactViewModel.class.getName());
 
 	private final ContactManager contactManager;
-	@DatabaseExecutor
-	private final Executor dbExecutor;
 
 	private final MutableLiveData<String> handshakeLink =
 			new MutableLiveData<>();
@@ -52,10 +53,12 @@ public class AddContactViewModel extends AndroidViewModel {
 	@Inject
 	AddContactViewModel(Application application,
 			ContactManager contactManager,
-			@DatabaseExecutor Executor dbExecutor) {
+			@DatabaseExecutor Executor dbExecutor,
-		super(application);
+			LifecycleManager lifecycleManager,
+			TransactionManager db,
+			AndroidExecutor androidExecutor) {
+		super(application, dbExecutor, lifecycleManager, db, androidExecutor);
 		this.contactManager = contactManager;
-		this.dbExecutor = dbExecutor;
 	}
 
 	void onCreate() {
@@ -63,7 +66,7 @@ public class AddContactViewModel extends AndroidViewModel {
 	}
 
 	private void loadHandshakeLink() {
-		dbExecutor.execute(() -> {
+		runOnDbThread(() -> {
 			try {
 				handshakeLink.postValue(contactManager.getHandshakeLink());
 			} catch (DbException e) {
@@ -102,7 +105,7 @@ public class AddContactViewModel extends AndroidViewModel {
 
 	void addContact(String nickname) {
 		if (remoteHandshakeLink == null) throw new IllegalStateException();
-		dbExecutor.execute(() -> {
+		runOnDbThread(() -> {
 			try {
 				contactManager.addPendingContact(remoteHandshakeLink, nickname);
 				addContactResult.postValue(new LiveResult<>(true));
@@ -122,11 +125,11 @@ public class AddContactViewModel extends AndroidViewModel {
 	}
 
 	public void updatePendingContact(String name, PendingContact p) {
-		dbExecutor.execute(() -> {
+		runOnDbThread(() -> {
 			try {
 				contactManager.removePendingContact(p.getId());
 				addContact(name);
-			} catch(NoSuchPendingContactException e) {
+			} catch (NoSuchPendingContactException e) {
 				logException(LOG, WARNING, e);
 				// no error in UI as pending contact was converted into contact
 			} catch (DbException e) {

briar-android/src/main/java/org/briarproject/briar/android/contact/add/remote/LinkExchangeFragment.java

@@ -33,7 +33,6 @@ import androidx.lifecycle.ViewModelProviders;
 
 import static android.content.Context.CLIPBOARD_SERVICE;
 import static android.widget.Toast.LENGTH_SHORT;
-import static java.util.Objects.requireNonNull;
 import static org.briarproject.bramble.api.contact.HandshakeLinkConstants.LINK_REGEX;
 import static org.briarproject.briar.android.util.UiUtils.observeOnce;
 
@@ -83,8 +82,8 @@ public class LinkExchangeFragment extends BaseFragment
 			linkInput.setText(viewModel.getRemoteHandshakeLink());
 		}
 
-		clipboard = (ClipboardManager) requireNonNull(
+		clipboard = (ClipboardManager)
-				getContext().getSystemService(CLIPBOARD_SERVICE));
+				requireContext().getSystemService(CLIPBOARD_SERVICE);
 
 		Button pasteButton = v.findViewById(R.id.pasteButton);
 		pasteButton.setOnClickListener(view -> {
@@ -107,7 +106,7 @@ public class LinkExchangeFragment extends BaseFragment
 
 	@Override
 	public void onGlobalLayout() {
-		ScrollView scrollView = (ScrollView) requireNonNull(getView());
+		ScrollView scrollView = (ScrollView) requireView();
 		View layout = scrollView.getChildAt(0);
 		int scrollBy = layout.getHeight() - scrollView.getHeight();
 		if (scrollBy > 0) {
@@ -121,7 +120,7 @@ public class LinkExchangeFragment extends BaseFragment
 	}
 
 	private void onHandshakeLinkLoaded(String link) {
-		View v = requireNonNull(getView());
+		View v = requireView();
 
 		TextView linkView = v.findViewById(R.id.linkView);
 		linkView.setText(link);

briar-android/src/main/java/org/briarproject/briar/android/contact/add/remote/NicknameFragment.java

@@ -31,6 +31,7 @@ import javax.inject.Inject;
 
 import androidx.annotation.StringRes;
 import androidx.appcompat.app.AlertDialog.Builder;
+import androidx.lifecycle.LifecycleOwner;
 import androidx.lifecycle.ViewModelProvider;
 import androidx.lifecycle.ViewModelProviders;
 
@@ -117,7 +118,8 @@ public class NicknameFragment extends BaseFragment {
 		addButton.setVisibility(INVISIBLE);
 		progressBar.setVisibility(VISIBLE);
 
-		viewModel.getAddContactResult().observe(this, result -> {
+		LifecycleOwner owner = getViewLifecycleOwner();
+		viewModel.getAddContactResult().observe(owner, result -> {
 			if (result == null) return;
 			if (result.hasError())
 				handleException(name, requireNonNull(result.getException()));

briar-android/src/main/java/org/briarproject/briar/android/contact/add/remote/PendingContactListViewModel.java

@@ -11,12 +11,16 @@ import org.briarproject.bramble.api.contact.event.PendingContactRemovedEvent;
 import org.briarproject.bramble.api.contact.event.PendingContactStateChangedEvent;
 import org.briarproject.bramble.api.db.DatabaseExecutor;
 import org.briarproject.bramble.api.db.DbException;
+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.lifecycle.LifecycleManager;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.rendezvous.RendezvousPoller;
 import org.briarproject.bramble.api.rendezvous.event.RendezvousPollEvent;
+import org.briarproject.bramble.api.system.AndroidExecutor;
+import org.briarproject.briar.android.viewmodel.DbViewModel;
 
 import java.util.ArrayList;
 import java.util.Collection;
@@ -26,7 +30,6 @@ import java.util.logging.Logger;
 
 import javax.inject.Inject;
 
-import androidx.lifecycle.AndroidViewModel;
 import androidx.lifecycle.LiveData;
 import androidx.lifecycle.MutableLiveData;
 
@@ -36,14 +39,12 @@ import static org.briarproject.bramble.api.contact.PendingContactState.OFFLINE;
 import static org.briarproject.bramble.util.LogUtils.logException;
 
 @NotNullByDefault
-public class PendingContactListViewModel extends AndroidViewModel
+public class PendingContactListViewModel extends DbViewModel
 		implements EventListener {
 
 	private final Logger LOG =
 			getLogger(PendingContactListViewModel.class.getName());
 
-	@DatabaseExecutor
-	private final Executor dbExecutor;
 	private final ContactManager contactManager;
 	private final RendezvousPoller rendezvousPoller;
 	private final EventBus eventBus;
@@ -56,11 +57,13 @@ public class PendingContactListViewModel extends AndroidViewModel
 	@Inject
 	PendingContactListViewModel(Application application,
 			@DatabaseExecutor Executor dbExecutor,
+			LifecycleManager lifecycleManager,
+			TransactionManager db,
+			AndroidExecutor androidExecutor,
 			ContactManager contactManager,
 			RendezvousPoller rendezvousPoller,
 			EventBus eventBus) {
-		super(application);
+		super(application, dbExecutor, lifecycleManager, db, androidExecutor);
-		this.dbExecutor = dbExecutor;
 		this.contactManager = contactManager;
 		this.rendezvousPoller = rendezvousPoller;
 		this.eventBus = eventBus;
@@ -87,7 +90,7 @@ public class PendingContactListViewModel extends AndroidViewModel
 	}
 
 	private void loadPendingContacts() {
-		dbExecutor.execute(() -> {
+		runOnDbThread(() -> {
 			try {
 				Collection<Pair<PendingContact, PendingContactState>> pairs =
 						contactManager.getPendingContacts();
@@ -113,7 +116,7 @@ public class PendingContactListViewModel extends AndroidViewModel
 	}
 
 	void removePendingContact(PendingContactId id) {
-		dbExecutor.execute(() -> {
+		runOnDbThread(() -> {
 			try {
 				contactManager.removePendingContact(id);
 			} catch (DbException e) {

briar-android/src/main/java/org/briarproject/briar/android/contactselection/BaseContactSelectorFragment.java

@@ -26,7 +26,6 @@ import javax.annotation.Nullable;
 import androidx.annotation.CallSuper;
 import androidx.recyclerview.widget.LinearLayoutManager;
 
-import static java.util.Objects.requireNonNull;
 import static org.briarproject.briar.android.activity.BriarActivity.GROUP_ID;
 import static org.briarproject.briar.android.contactselection.ContactSelectorActivity.CONTACTS;
 import static org.briarproject.briar.android.contactselection.ContactSelectorActivity.getContactsFromIds;
@@ -55,7 +54,7 @@ public abstract class BaseContactSelectorFragment<I extends SelectableContactIte
 	public void onCreate(@Nullable Bundle savedInstanceState) {
 		super.onCreate(savedInstanceState);
 
-		Bundle args = requireNonNull(getArguments());
+		Bundle args = requireArguments();
 		byte[] b = args.getByteArray(GROUP_ID);
 		if (b == null) throw new IllegalStateException("No GroupId");
 		groupId = new GroupId(b);
@@ -74,7 +73,7 @@ public abstract class BaseContactSelectorFragment<I extends SelectableContactIte
 		list.setEmptyImage(R.drawable.ic_empty_state_contact_list);
 		list.setEmptyText(getString(R.string.no_contacts_selector));
 		list.setEmptyAction(getString(R.string.no_contacts_selector_action));
-		adapter = getAdapter(requireNonNull(getContext()), this);
+		adapter = getAdapter(requireContext(), this);
 		list.setAdapter(adapter);
 
 		// restore selected contacts if available
@@ -134,7 +133,7 @@ public abstract class BaseContactSelectorFragment<I extends SelectableContactIte
 
 					@Override
 					public void onExceptionUi(DbException exception) {
-						handleDbException(exception);
+						handleException(exception);
 					}
 				});
 	}

briar-android/src/main/java/org/briarproject/briar/android/controller/DbController.java

@@ -2,6 +2,7 @@ package org.briarproject.briar.android.controller;
 
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 
+@Deprecated
 @NotNullByDefault
 public interface DbController {
 

briar-android/src/main/java/org/briarproject/briar/android/controller/DbControllerImpl.java

@@ -11,6 +11,7 @@ import javax.annotation.concurrent.Immutable;
 import javax.inject.Inject;
 
 @Immutable
+@Deprecated
 @NotNullByDefault
 public class DbControllerImpl implements DbController {
 

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;
@@ -97,9 +95,9 @@ 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;
 import androidx.recyclerview.selection.Selection;
 import androidx.recyclerview.selection.SelectionPredicates;
 import androidx.recyclerview.selection.SelectionTracker;
@@ -118,8 +116,6 @@ 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 +132,7 @@ 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 +182,6 @@ 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();
@@ -228,8 +223,9 @@ public class ConversationActivity extends BriarActivity
 		if (id == -1) throw new IllegalStateException();
 		contactId = new ContactId(id);
 
-		viewModel = ViewModelProviders.of(this, viewModelFactory)
+		viewModel = new ViewModelProvider(this, viewModelFactory)
 				.get(ConversationViewModel.class);
+		viewModel.setContactId(contactId);
 		attachmentRetriever = viewModel.getAttachmentRetriever();
 
 		setContentView(R.layout.activity_conversation);
@@ -334,16 +330,6 @@ public class ConversationActivity extends BriarActivity
 		list.startPeriodicUpdate();
 	}
 
-	@Override
-	public void onResume() {
-		super.onResume();
-		// Trigger loading of contact data, noop if data was loaded already.
-		//
-		// We can only start loading data *after* we are sure
-		// the user has signed in. After sign-in, onCreate() isn't run again.
-		if (signedIn()) viewModel.setContactId(contactId);
-	}
-
 	@Override
 	public void onStop() {
 		super.onStop();
@@ -540,6 +526,7 @@ public class ConversationActivity extends BriarActivity
 		});
 	}
 
+	@DatabaseExecutor
 	private void eagerlyLoadMessageSize(PrivateMessageHeader h) {
 		try {
 			MessageId id = h.getId();
@@ -556,21 +543,11 @@ 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);
+				LOG.info("Eagerly loading image size for latest message");
-				if (items == null) {
+				AttachmentHeader header = headers.get(0);
-					LOG.info("Eagerly loading image size for latest message");
+				// get the item to retrieve its size
-					AttachmentHeader header = headers.get(0);
+				attachmentRetriever
-					try {
+						.cacheAttachmentItemWithSize(h.getId(), header);
-						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);
-					}
-				}
 			}
 		} catch (DbException e) {
 			logException(LOG, WARNING, e);
@@ -651,59 +628,18 @@ public class ConversationActivity extends BriarActivity
 				&& adapter.isScrolledToBottom(layoutManager);
 	}
 
-	private void loadMessageAttachments(PrivateMessageHeader h) {
+	@UiThread
-		// TODO: Use placeholders for missing/invalid attachments
+	private void updateMessageAttachment(MessageId m, AttachmentItem item) {
-		runOnDbThread(() -> {
+		Pair<Integer, ConversationMessageItem> pair = adapter.getMessageItem(m);
-			try {
+		if (pair != null && pair.getSecond().updateAttachments(item)) {
-				// TODO move getting the items off to IoExecutor, if size == 1
+			boolean scroll = shouldScrollWhenUpdatingMessage();
-				List<AttachmentHeader> headers = h.getAttachmentHeaders();
+			adapter.notifyItemChanged(pair.getFirst());
-				boolean needsSize = headers.size() == 1;
+			if (scroll) scrollToBottom();
-				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();
-			}
-		});
 	}
 
 	@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 +699,6 @@ 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 +707,7 @@ 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 +1034,9 @@ 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 +1075,41 @@ public class ConversationActivity extends BriarActivity
 		return text;
 	}
 
+	/**
+	 * Called by {@link PrivateMessageHeader#accept(ConversationMessageVisitor)}
+	 */
 	@Override
 	public List<AttachmentItem> getAttachmentItems(PrivateMessageHeader h) {
-		List<AttachmentItem> attachments =
+		List<LiveData<AttachmentItem>> liveDataList =
-				attachmentRetriever.cacheGet(h.getId());
+				attachmentRetriever.getAttachmentItems(h);
-		if (attachments == null) {
+		List<AttachmentItem> items = new ArrayList<>(liveDataList.size());
-			loadMessageAttachments(h);
+		for (LiveData<AttachmentItem> liveData : liveDataList) {
-			return emptyList();
+			// 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) {
+	@UiThread
-		this.attachments = attachments;
+	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

@@ -11,18 +11,24 @@ 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.lifecycle.LifecycleManager;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.settings.Settings;
 import org.briarproject.bramble.api.settings.SettingsManager;
 import org.briarproject.bramble.api.sync.GroupId;
 import org.briarproject.bramble.api.sync.Message;
 import org.briarproject.bramble.api.sync.MessageId;
+import org.briarproject.bramble.api.system.AndroidExecutor;
 import org.briarproject.briar.android.attachment.AttachmentCreator;
 import org.briarproject.briar.android.attachment.AttachmentManager;
 import org.briarproject.briar.android.attachment.AttachmentResult;
 import org.briarproject.briar.android.attachment.AttachmentRetriever;
 import org.briarproject.briar.android.util.UiUtils;
+import org.briarproject.briar.android.viewmodel.DbViewModel;
 import org.briarproject.briar.android.viewmodel.LiveEvent;
 import org.briarproject.briar.android.viewmodel.MutableLiveEvent;
 import org.briarproject.briar.api.messaging.AttachmentHeader;
@@ -30,6 +36,7 @@ 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;
@@ -40,7 +47,6 @@ import javax.inject.Inject;
 
 import androidx.annotation.Nullable;
 import androidx.annotation.UiThread;
-import androidx.lifecycle.AndroidViewModel;
 import androidx.lifecycle.LiveData;
 import androidx.lifecycle.MutableLiveData;
 import androidx.lifecycle.Transformations;
@@ -55,10 +61,10 @@ import static org.briarproject.briar.android.settings.SettingsFragment.SETTINGS_
 import static org.briarproject.briar.android.util.UiUtils.observeForeverOnce;
 
 @NotNullByDefault
-public class ConversationViewModel extends AndroidViewModel
+public class ConversationViewModel extends DbViewModel
-		implements AttachmentManager {
+		implements EventListener, AttachmentManager {
 
-	private static Logger LOG =
+	private static final Logger LOG =
 			getLogger(ConversationViewModel.class.getName());
 
 	private static final String SHOW_ONBOARDING_IMAGE =
@@ -66,9 +72,8 @@ public class ConversationViewModel extends AndroidViewModel
 	private static final String SHOW_ONBOARDING_INTRODUCTION =
 			"showOnboardingIntroduction";
 
-	@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;
@@ -100,16 +105,19 @@ public class ConversationViewModel extends AndroidViewModel
 	@Inject
 	ConversationViewModel(Application application,
 			@DatabaseExecutor Executor dbExecutor,
+			LifecycleManager lifecycleManager,
 			TransactionManager db,
+			AndroidExecutor androidExecutor,
+			EventBus eventBus,
 			MessagingManager messagingManager,
 			ContactManager contactManager,
 			SettingsManager settingsManager,
 			PrivateMessageFactory privateMessageFactory,
 			AttachmentRetriever attachmentRetriever,
 			AttachmentCreator attachmentCreator) {
-		super(application);
+		super(application, dbExecutor, lifecycleManager, db, androidExecutor);
-		this.dbExecutor = dbExecutor;
 		this.db = db;
+		this.eventBus = eventBus;
 		this.messagingManager = messagingManager;
 		this.contactManager = contactManager;
 		this.settingsManager = settingsManager;
@@ -119,12 +127,27 @@ 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");
+				runOnDbThread(() -> attachmentRetriever
+						.loadAttachmentItem(a.getMessageId()));
+			}
+		}
 	}
 
 	/**
@@ -141,7 +164,7 @@ public class ConversationViewModel extends AndroidViewModel
 	}
 
 	private void loadContact(ContactId contactId) {
-		dbExecutor.execute(() -> {
+		runOnDbThread(() -> {
 			try {
 				long start = now();
 				Contact c = contactManager.getContact(contactId);
@@ -159,7 +182,7 @@ public class ConversationViewModel extends AndroidViewModel
 	}
 
 	void markMessageRead(GroupId g, MessageId m) {
-		dbExecutor.execute(() -> {
+		runOnDbThread(() -> {
 			try {
 				long start = now();
 				messagingManager.setReadFlag(g, m, true);
@@ -171,7 +194,7 @@ public class ConversationViewModel extends AndroidViewModel
 	}
 
 	void setContactAlias(String alias) {
-		dbExecutor.execute(() -> {
+		runOnDbThread(() -> {
 			try {
 				contactManager.setContactAlias(requireNonNull(contactId),
 						alias.isEmpty() ? null : alias);
@@ -252,6 +275,7 @@ 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) {
@@ -270,9 +294,10 @@ public class ConversationViewModel extends AndroidViewModel
 		}
 	}
 
+	@UiThread
 	private void storeMessage(PrivateMessage m) {
 		attachmentCreator.onAttachmentsSent(m.getMessage().getId());
-		dbExecutor.execute(() -> {
+		runOnDbThread(() -> {
 			try {
 				long start = now();
 				messagingManager.addLocalMessage(m);
@@ -332,7 +357,7 @@ public class ConversationViewModel extends AndroidViewModel
 
 	@UiThread
 	void recheckFeaturesAndOnboarding(ContactId contactId) {
-		dbExecutor.execute(() -> {
+		runOnDbThread(() -> {
 			try {
 				checkFeaturesAndOnboarding(contactId);
 			} catch (DbException e) {

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
+		// Set contact name and message time
-		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);
 		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
+			Fragment f = ImageFragment.newInstance(
-					.newInstance(attachments.get(position), isFirst);
+					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;
@@ -23,8 +24,10 @@ 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.LifecycleOwner;
 import androidx.lifecycle.ViewModelProvider;
 import androidx.lifecycle.ViewModelProviders;
 
@@ -32,27 +35,36 @@ 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;
 	}
@@ -67,9 +79,11 @@ public class ImageFragment extends Fragment {
 	public void onCreate(@Nullable Bundle savedInstanceState) {
 		super.onCreate(savedInstanceState);
 
-		Bundle args = requireNonNull(getArguments());
+		Bundle args = requireArguments();
 		attachment = requireNonNull(args.getParcelable(ATTACHMENT_POSITION));
 		isFirst = args.getBoolean(IS_FIRST);
+		conversationItemId =
+				new MessageId(requireNonNull(args.getByteArray(ITEM_ID)));
 	}
 
 	@Nullable
@@ -80,57 +94,76 @@ public class ImageFragment extends Fragment {
 		View v = inflater.inflate(R.layout.fragment_image, container,
 				false);
 
-		viewModel = ViewModelProviders.of(requireNonNull(getActivity()),
+		viewModel = ViewModelProviders.of(requireActivity(),
 				viewModelFactory).get(ImageViewModel.class);
 
 		photoView = v.findViewById(R.id.photoView);
 		photoView.setScaleLevels(1, 2, 4);
 		photoView.setOnClickListener(view -> viewModel.clickImage());
 
-		// Request Listener
+		if (attachment.getState() == AVAILABLE) {
-		RequestListener<Drawable> listener = new RequestListener<Drawable>() {
+			loadImage();
-
+			// postponed transition will be started when Image was loaded
-			@Override
+		} else if (attachment.getState() == ERROR) {
-			public boolean onLoadFailed(@Nullable GlideException e,
+			photoView.setImageResource(ERROR_RES);
-					Object model, Target<Drawable> target,
+			startPostponedTransition();
-					boolean isFirstResource) {
+		} else {
-				if (getActivity() != null && isFirst)
+			photoView.setImageResource(R.drawable.ic_image_missing);
-					getActivity().supportStartPostponedEnterTransition();
+			startPostponedTransition();
-				return false;
+			// state is not final, so observe state changes
-			}
+			LifecycleOwner owner = getViewLifecycleOwner();
-
+			viewModel.getOnAttachmentReceived(attachment.getMessageId())
-			@Override
+					.observeEvent(owner, this::onAttachmentReceived);
-			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);
 
 		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()) {
+		setImageViewDimensions(attachment, single, needsStretch);
-			GlideApp.with(imageView)
+		if (attachment.getState() != AVAILABLE) {
-					.clear(imageView);
+			GlideApp.with(imageView).clear(imageView);
-			imageView.setImageResource(ERROR_RES);
+			if (attachment.getState() == ERROR) {
-		} else {
+				imageView.setImageResource(ERROR_RES);
-			setImageViewDimensions(attachment, single, needsStretch);
+			} else {
-			loadImage(attachment, r);
+				imageView.setImageResource(R.drawable.ic_image_missing);
-			if (SDK_INT >= 21) {
-				imageView.setTransitionName(attachment.getTransitionName());
 			}
+			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 +7,22 @@ import android.view.View;
 
 import org.briarproject.bramble.api.db.DatabaseExecutor;
 import org.briarproject.bramble.api.db.DbException;
+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.lifecycle.IoExecutor;
+import org.briarproject.bramble.api.lifecycle.LifecycleManager;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.sync.MessageId;
+import org.briarproject.bramble.api.system.AndroidExecutor;
 import org.briarproject.briar.android.attachment.AttachmentItem;
+import org.briarproject.briar.android.viewmodel.DbViewModel;
 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 +31,8 @@ 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;
@@ -30,27 +41,30 @@ import javax.inject.Inject;
 
 import androidx.annotation.Nullable;
 import androidx.annotation.UiThread;
-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 DbViewModel implements EventListener {
 
-	private static Logger LOG = getLogger(ImageViewModel.class.getName());
+	private static final Logger LOG = getLogger(ImageViewModel.class.getName());
 
 	private final MessagingManager messagingManager;
-	@DatabaseExecutor
+	private final EventBus eventBus;
-	private final Executor dbExecutor;
 	@IoExecutor
 	private final Executor ioExecutor;
 
+	private boolean receivedAttachmentsInitialized = false;
+	private final HashMap<MessageId, MutableLiveEvent<Boolean>>
+			receivedAttachments = new HashMap<>();
+
 	/**
 	 * true means there was an error saving the image, false if image was saved.
 	 */
@@ -63,12 +77,62 @@ public class ImageViewModel extends AndroidViewModel {
 	@Inject
 	ImageViewModel(Application application,
 			MessagingManager messagingManager,
+			EventBus eventBus,
 			@DatabaseExecutor Executor dbExecutor,
+			LifecycleManager lifecycleManager,
+			TransactionManager db,
+			AndroidExecutor androidExecutor,
 			@IoExecutor Executor ioExecutor) {
-		super(application);
+		super(application, dbExecutor, lifecycleManager, db, androidExecutor);
 		this.messagingManager = messagingManager;
-		this.dbExecutor = dbExecutor;
+		this.eventBus = eventBus;
 		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() {
@@ -135,7 +199,7 @@ public class ImageViewModel extends AndroidViewModel {
 
 	private void saveImage(AttachmentItem attachment, OutputStreamProvider osp,
 			@Nullable Runnable afterCopy) {
-		dbExecutor.execute(() -> {
+		runOnDbThread(() -> {
 			try {
 				Attachment a =
 						messagingManager.getAttachment(attachment.getHeader());

briar-android/src/main/java/org/briarproject/briar/android/forum/ForumActivity.java

@@ -38,7 +38,7 @@ import static org.briarproject.briar.api.forum.ForumConstants.MAX_FORUM_POST_TEX
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
 public class ForumActivity extends
-		ThreadListActivity<Forum, ForumItem, ThreadItemAdapter<ForumItem>>
+		ThreadListActivity<Forum, ForumPostItem, ThreadItemAdapter<ForumPostItem>>
 		implements ForumListener {
 
 	@Inject
@@ -50,7 +50,7 @@ public class ForumActivity extends
 	}
 
 	@Override
-	protected ThreadListController<Forum, ForumItem> getController() {
+	protected ThreadListController<Forum, ForumPostItem> getController() {
 		return forumController;
 	}
 
@@ -82,7 +82,7 @@ public class ForumActivity extends
 	}
 
 	@Override
-	protected ThreadItemAdapter<ForumItem> createAdapter(
+	protected ThreadItemAdapter<ForumPostItem> createAdapter(
 			LinearLayoutManager layoutManager) {
 		return new ThreadItemAdapter<>(this, layoutManager);
 	}
@@ -156,7 +156,7 @@ public class ForumActivity extends
 
 					@Override
 					public void onExceptionUi(DbException exception) {
-						handleDbException(exception);
+						handleException(exception);
 					}
 				});
 	}

briar-android/src/main/java/org/briarproject/briar/android/forum/ForumController.java

@@ -8,9 +8,9 @@ import org.briarproject.briar.api.forum.Forum;
 import androidx.annotation.UiThread;
 
 @NotNullByDefault
-interface ForumController extends ThreadListController<Forum, ForumItem> {
+interface ForumController extends ThreadListController<Forum, ForumPostItem> {
 
-	interface ForumListener extends ThreadListListener<ForumItem> {
+	interface ForumListener extends ThreadListListener<ForumPostItem> {
 		@UiThread
 		void onForumLeft(ContactId c);
 	}

briar-android/src/main/java/org/briarproject/briar/android/forum/ForumControllerImpl.java

@@ -43,7 +43,7 @@ import static org.briarproject.bramble.util.LogUtils.logException;
 
 @NotNullByDefault
 class ForumControllerImpl extends
-		ThreadListControllerImpl<Forum, ForumItem, ForumPostHeader, ForumPost, ForumListener>
+		ThreadListControllerImpl<Forum, ForumPostItem, ForumPostHeader, ForumPost, ForumListener>
 		implements ForumController {
 
 	private static final Logger LOG =
@@ -138,8 +138,8 @@ class ForumControllerImpl extends
 
 	@Override
 	public void createAndStoreMessage(String text,
-			@Nullable ForumItem parentItem,
+			@Nullable ForumPostItem parentItem,
-			ResultExceptionHandler<ForumItem, DbException> handler) {
+			ResultExceptionHandler<ForumPostItem, DbException> handler) {
 		runOnDbThread(() -> {
 			try {
 				LocalAuthor author = identityManager.getLocalAuthor();
@@ -158,7 +158,7 @@ class ForumControllerImpl extends
 
 	private void createMessage(String text, long timestamp,
 			@Nullable MessageId parentId, LocalAuthor author,
-			ResultExceptionHandler<ForumItem, DbException> handler) {
+			ResultExceptionHandler<ForumPostItem, DbException> handler) {
 		cryptoExecutor.execute(() -> {
 			LOG.info("Creating forum post...");
 			ForumPost msg = forumManager.createLocalPost(getGroupId(), text,
@@ -178,8 +178,8 @@ class ForumControllerImpl extends
 	}
 
 	@Override
-	protected ForumItem buildItem(ForumPostHeader header, String text) {
+	protected ForumPostItem buildItem(ForumPostHeader header, String text) {
-		return new ForumItem(header, text);
+		return new ForumPostItem(header, text);
 	}
 
 }

briar-android/src/main/java/org/briarproject/briar/android/forum/ForumListAdapter.java

@@ -1,134 +1,47 @@
 package org.briarproject.briar.android.forum;
 
-import android.content.Context;
-import android.content.Intent;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
-import android.widget.TextView;
 
-import org.briarproject.bramble.api.sync.GroupId;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.briar.R;
-import org.briarproject.briar.android.util.BriarAdapter;
-import org.briarproject.briar.android.util.UiUtils;
-import org.briarproject.briar.android.view.TextAvatarView;
-import org.briarproject.briar.api.forum.Forum;
 
-import androidx.recyclerview.widget.RecyclerView;
+import androidx.recyclerview.widget.DiffUtil.ItemCallback;
+import androidx.recyclerview.widget.ListAdapter;
 
-import static android.view.View.GONE;
+@NotNullByDefault
-import static android.view.View.VISIBLE;
+class ForumListAdapter extends ListAdapter<ForumListItem, ForumViewHolder> {
-import static androidx.recyclerview.widget.SortedList.INVALID_POSITION;
-import static org.briarproject.briar.android.activity.BriarActivity.GROUP_ID;
-import static org.briarproject.briar.android.activity.BriarActivity.GROUP_NAME;
 
-class ForumListAdapter
+	ForumListAdapter() {
-		extends BriarAdapter<ForumListItem, ForumListAdapter.ForumViewHolder> {
+		super(new ForumListCallback());
-
-	ForumListAdapter(Context ctx) {
-		super(ctx, ForumListItem.class);
 	}
 
 	@Override
 	public ForumViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
-		View v = LayoutInflater.from(ctx).inflate(
+		View v = LayoutInflater.from(parent.getContext()).inflate(
 				R.layout.list_item_forum, parent, false);
 		return new ForumViewHolder(v);
 	}
 
 	@Override
-	public void onBindViewHolder(ForumViewHolder ui, int position) {
+	public void onBindViewHolder(ForumViewHolder viewHolder, int position) {
-		ForumListItem item = getItemAt(position);
+		viewHolder.bind(getItem(position));
-		if (item == null) return;
+	}
 
-		// Avatar
+	@NotNullByDefault
-		ui.avatar.setText(item.getForum().getName().substring(0, 1));
+	private static class ForumListCallback extends ItemCallback<ForumListItem> {
-		ui.avatar.setBackgroundBytes(item.getForum().getId().getBytes());
+		@Override
-		ui.avatar.setUnreadCount(item.getUnreadCount());
+		public boolean areItemsTheSame(ForumListItem a, ForumListItem b) {
-
+			return a.equals(b);
-		// Forum Name
-		ui.name.setText(item.getForum().getName());
-
-		// Post Count
-		int postCount = item.getPostCount();
-		if (postCount > 0) {
-			ui.postCount.setText(ctx.getResources()
-					.getQuantityString(R.plurals.posts, postCount,
-							postCount));
-		} else {
-			ui.postCount.setText(ctx.getString(R.string.no_posts));
 		}
 
-		// Date
+		@Override
-		if (item.isEmpty()) {
+		public boolean areContentsTheSame(ForumListItem a, ForumListItem b) {
-			ui.date.setVisibility(GONE);
+			return a.isEmpty() == b.isEmpty() &&
-		} else {
+					a.getTimestamp() == b.getTimestamp() &&
-			long timestamp = item.getTimestamp();
+					a.getUnreadCount() == b.getUnreadCount();
-			ui.date.setText(UiUtils.formatDate(ctx, timestamp));
-			ui.date.setVisibility(VISIBLE);
-		}
-
-		// Open Forum on Click
-		ui.layout.setOnClickListener(v -> {
-			Intent i = new Intent(ctx, ForumActivity.class);
-			Forum f = item.getForum();
-			i.putExtra(GROUP_ID, f.getId().getBytes());
-			i.putExtra(GROUP_NAME, f.getName());
-			ctx.startActivity(i);
-		});
-	}
-
-	@Override
-	public int compare(ForumListItem a, ForumListItem b) {
-		if (a == b) return 0;
-		// The forum with the newest message comes first
-		long aTime = a.getTimestamp(), bTime = b.getTimestamp();
-		if (aTime > bTime) return -1;
-		if (aTime < bTime) return 1;
-		// Break ties by forum name
-		String aName = a.getForum().getName();
-		String bName = b.getForum().getName();
-		return String.CASE_INSENSITIVE_ORDER.compare(aName, bName);
-	}
-
-	@Override
-	public boolean areContentsTheSame(ForumListItem a, ForumListItem b) {
-		return a.isEmpty() == b.isEmpty() &&
-				a.getTimestamp() == b.getTimestamp() &&
-				a.getUnreadCount() == b.getUnreadCount();
-	}
-
-	@Override
-	public boolean areItemsTheSame(ForumListItem a, ForumListItem b) {
-		return a.getForum().equals(b.getForum());
-	}
-
-	int findItemPosition(GroupId g) {
-		int count = getItemCount();
-		for (int i = 0; i < count; i++) {
-			ForumListItem item = getItemAt(i);
-			if (item != null && item.getForum().getGroup().getId().equals(g))
-				return i;
-		}
-		return INVALID_POSITION; // Not found
-	}
-
-	static class ForumViewHolder extends RecyclerView.ViewHolder {
-
-		private final ViewGroup layout;
-		private final TextAvatarView avatar;
-		private final TextView name;
-		private final TextView postCount;
-		private final TextView date;
-
-		private ForumViewHolder(View v) {
-			super(v);
-
-			layout = (ViewGroup) v;
-			avatar = v.findViewById(R.id.avatarView);
-			name = v.findViewById(R.id.forumNameView);
-			postCount = v.findViewById(R.id.postCountView);
-			date = v.findViewById(R.id.dateView);
 		}
 	}
+
 }

briar-android/src/main/java/org/briarproject/briar/android/forum/ForumListFragment.java

@@ -12,81 +12,48 @@ import android.view.ViewGroup;
 
 import com.google.android.material.snackbar.Snackbar;
 
-import org.briarproject.bramble.api.contact.event.ContactRemovedEvent;
-import org.briarproject.bramble.api.db.DbException;
-import org.briarproject.bramble.api.db.NoSuchGroupException;
-import org.briarproject.bramble.api.event.Event;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
-import org.briarproject.bramble.api.sync.GroupId;
-import org.briarproject.bramble.api.sync.event.GroupAddedEvent;
-import org.briarproject.bramble.api.sync.event.GroupRemovedEvent;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.activity.ActivityComponent;
-import org.briarproject.briar.android.fragment.BaseEventFragment;
+import org.briarproject.briar.android.fragment.BaseFragment;
 import org.briarproject.briar.android.sharing.ForumInvitationActivity;
 import org.briarproject.briar.android.util.BriarSnackbarBuilder;
 import org.briarproject.briar.android.view.BriarRecyclerView;
-import org.briarproject.briar.api.android.AndroidNotificationManager;
-import org.briarproject.briar.api.client.MessageTracker.GroupCount;
-import org.briarproject.briar.api.forum.Forum;
-import org.briarproject.briar.api.forum.ForumManager;
-import org.briarproject.briar.api.forum.ForumPostHeader;
-import org.briarproject.briar.api.forum.ForumSharingManager;
-import org.briarproject.briar.api.forum.event.ForumInvitationRequestReceivedEvent;
-import org.briarproject.briar.api.forum.event.ForumPostReceivedEvent;
-
-import java.util.ArrayList;
-import java.util.Collection;
-import java.util.logging.Logger;
 
 import javax.annotation.Nullable;
 import javax.inject.Inject;
 
-import androidx.annotation.UiThread;
+import androidx.lifecycle.ViewModelProvider;
 import androidx.recyclerview.widget.LinearLayoutManager;
 
 import static com.google.android.material.snackbar.Snackbar.LENGTH_INDEFINITE;
 import static java.util.Objects.requireNonNull;
-import static java.util.logging.Level.WARNING;
-import static org.briarproject.bramble.util.LogUtils.logDuration;
-import static org.briarproject.bramble.util.LogUtils.logException;
-import static org.briarproject.bramble.util.LogUtils.now;
-import static org.briarproject.briar.api.forum.ForumManager.CLIENT_ID;
 
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
-public class ForumListFragment extends BaseEventFragment implements
+public class ForumListFragment extends BaseFragment implements
 		OnClickListener {
 
 	public final static String TAG = ForumListFragment.class.getName();
-	private final static Logger LOG = Logger.getLogger(TAG);
 
+	private ForumListViewModel viewModel;
 	private BriarRecyclerView list;
-	private ForumListAdapter adapter;
 	private Snackbar snackbar;
+	private final ForumListAdapter adapter = new ForumListAdapter();
 
 	@Inject
-	AndroidNotificationManager notificationManager;
+	ViewModelProvider.Factory viewModelFactory;
-
-	// Fields that are accessed from background threads must be volatile
-	@Inject
-	volatile ForumManager forumManager;
-	@Inject
-	volatile ForumSharingManager forumSharingManager;
 
 	public static ForumListFragment newInstance() {
-
+		return new ForumListFragment();
-		Bundle args = new Bundle();
-
-		ForumListFragment fragment = new ForumListFragment();
-		fragment.setArguments(args);
-		return fragment;
 	}
 
 	@Override
 	public void injectFragment(ActivityComponent component) {
 		component.inject(this);
+		viewModel = new ViewModelProvider(this, viewModelFactory)
+				.get(ForumListViewModel.class);
 	}
 
 	@Nullable
@@ -94,24 +61,35 @@ public class ForumListFragment extends BaseEventFragment implements
 	public View onCreateView(LayoutInflater inflater,
 			@Nullable ViewGroup container,
 			@Nullable Bundle savedInstanceState) {
+		requireActivity().setTitle(R.string.forums_button);
 
-		requireNonNull(getActivity()).setTitle(R.string.forums_button);
+		View v = inflater.inflate(R.layout.fragment_forum_list, container,
+				false);
 
-		View contentView =
+		list = v.findViewById(R.id.forumList);
-				inflater.inflate(R.layout.fragment_forum_list, container,
-						false);
-
-		adapter = new ForumListAdapter(getActivity());
-
-		list = contentView.findViewById(R.id.forumList);
 		list.setLayoutManager(new LinearLayoutManager(getActivity()));
 		list.setAdapter(adapter);
+		viewModel.getForumListItems().observe(getViewLifecycleOwner(), result ->
+				result.onError(this::handleException).onSuccess(items -> {
+					adapter.submitList(items);
+					if (requireNonNull(items).size() == 0) list.showData();
+				})
+		);
 
 		snackbar = new BriarSnackbarBuilder()
 				.setAction(R.string.show, this)
 				.make(list, "", LENGTH_INDEFINITE);
+		viewModel.getNumInvitations().observe(getViewLifecycleOwner(), num -> {
+			if (num == 0) {
+				snackbar.dismiss();
+			} else {
+				snackbar.setText(getResources().getQuantityString(
+						R.plurals.forums_shared, num, num));
+				if (!snackbar.isShownOrQueued()) snackbar.show();
+			}
+		});
 
-		return contentView;
+		return v;
 	}
 
 	@Override
@@ -122,18 +100,23 @@ public class ForumListFragment extends BaseEventFragment implements
 	@Override
 	public void onStart() {
 		super.onStart();
-		notificationManager.clearAllForumPostNotifications();
+		viewModel.blockAllForumPostNotifications();
-		loadForums();
+		viewModel.clearAllForumPostNotifications();
-		loadAvailableForums();
+		// The attributes and sorting of the forums may have changed while we
+		// were stopped and we have no way finding out about them, so re-load
+		// e.g. less unread posts in a forum after viewing it.
+		viewModel.loadForums();
+		// The number of invitations might have changed while we were stopped
+		// e.g. because of accepting an invitation which does not trigger event
+		viewModel.loadForumInvitations();
 		list.startPeriodicUpdate();
 	}
 
 	@Override
 	public void onStop() {
 		super.onStop();
-		adapter.clear();
-		list.showProgressBar();
 		list.stopPeriodicUpdate();
+		viewModel.unblockAllForumPostNotifications();
 	}
 
 	@Override
@@ -145,123 +128,12 @@ public class ForumListFragment extends BaseEventFragment implements
 	@Override
 	public boolean onOptionsItemSelected(MenuItem item) {
 		// Handle presses on the action bar items
-		switch (item.getItemId()) {
+		if (item.getItemId() == R.id.action_create_forum) {
-			case R.id.action_create_forum:
+			Intent intent = new Intent(getContext(), CreateForumActivity.class);
-				Intent intent =
+			startActivity(intent);
-						new Intent(getContext(), CreateForumActivity.class);
+			return true;
-				startActivity(intent);
-				return true;
-			default:
-				return super.onOptionsItemSelected(item);
 		}
-	}
+		return super.onOptionsItemSelected(item);
-
-	private void loadForums() {
-		int revision = adapter.getRevision();
-		listener.runOnDbThread(() -> {
-			try {
-				long start = now();
-				Collection<ForumListItem> forums = new ArrayList<>();
-				for (Forum f : forumManager.getForums()) {
-					try {
-						GroupCount count =
-								forumManager.getGroupCount(f.getId());
-						forums.add(new ForumListItem(f, count));
-					} catch (NoSuchGroupException e) {
-						// Continue
-					}
-				}
-				logDuration(LOG, "Full load", start);
-				displayForums(revision, forums);
-			} catch (DbException e) {
-				logException(LOG, WARNING, e);
-			}
-		});
-	}
-
-	private void displayForums(int revision, Collection<ForumListItem> forums) {
-		runOnUiThreadUnlessDestroyed(() -> {
-			if (revision == adapter.getRevision()) {
-				adapter.incrementRevision();
-				if (forums.isEmpty()) list.showData();
-				else adapter.replaceAll(forums);
-			} else {
-				LOG.info("Concurrent update, reloading");
-				loadForums();
-			}
-		});
-	}
-
-	private void loadAvailableForums() {
-		listener.runOnDbThread(() -> {
-			try {
-				long start = now();
-				int available = forumSharingManager.getInvitations().size();
-				logDuration(LOG, "Loading available", start);
-				displayAvailableForums(available);
-			} catch (DbException e) {
-				logException(LOG, WARNING, e);
-			}
-		});
-	}
-
-	private void displayAvailableForums(int availableCount) {
-		runOnUiThreadUnlessDestroyed(() -> {
-			if (availableCount == 0) {
-				snackbar.dismiss();
-			} else {
-				snackbar.setText(getResources().getQuantityString(
-						R.plurals.forums_shared, availableCount,
-						availableCount));
-				if (!snackbar.isShownOrQueued()) snackbar.show();
-			}
-		});
-	}
-
-	@Override
-	public void eventOccurred(Event e) {
-		if (e instanceof ContactRemovedEvent) {
-			LOG.info("Contact removed, reloading available forums");
-			loadAvailableForums();
-		} else if (e instanceof GroupAddedEvent) {
-			GroupAddedEvent g = (GroupAddedEvent) e;
-			if (g.getGroup().getClientId().equals(CLIENT_ID)) {
-				LOG.info("Forum added, reloading forums");
-				loadForums();
-			}
-		} else if (e instanceof GroupRemovedEvent) {
-			GroupRemovedEvent g = (GroupRemovedEvent) e;
-			if (g.getGroup().getClientId().equals(CLIENT_ID)) {
-				LOG.info("Forum removed, removing from list");
-				removeForum(g.getGroup().getId());
-			}
-		} else if (e instanceof ForumPostReceivedEvent) {
-			ForumPostReceivedEvent f = (ForumPostReceivedEvent) e;
-			LOG.info("Forum post added, updating item");
-			updateItem(f.getGroupId(), f.getHeader());
-		} else if (e instanceof ForumInvitationRequestReceivedEvent) {
-			LOG.info("Forum invitation received, reloading available forums");
-			loadAvailableForums();
-		}
-	}
-
-	@UiThread
-	private void updateItem(GroupId g, ForumPostHeader m) {
-		adapter.incrementRevision();
-		int position = adapter.findItemPosition(g);
-		ForumListItem item = adapter.getItemAt(position);
-		if (item != null) {
-			item.addHeader(m);
-			adapter.updateItemAt(position, item);
-		}
-	}
-
-	@UiThread
-	private void removeForum(GroupId g) {
-		adapter.incrementRevision();
-		int position = adapter.findItemPosition(g);
-		ForumListItem item = adapter.getItemAt(position);
-		if (item != null) adapter.remove(item);
 	}
 
 	@Override

briar-android/src/main/java/org/briarproject/briar/android/forum/ForumListItem.java

@@ -4,12 +4,16 @@ import org.briarproject.briar.api.client.MessageTracker.GroupCount;
 import org.briarproject.briar.api.forum.Forum;
 import org.briarproject.briar.api.forum.ForumPostHeader;
 
-// This class is NOT thread-safe
+import javax.annotation.concurrent.Immutable;
-class ForumListItem {
+
+import androidx.annotation.Nullable;
+
+@Immutable
+class ForumListItem implements Comparable<ForumListItem> {
 
 	private final Forum forum;
-	private int postCount, unread;
+	private final int postCount, unread;
-	private long timestamp;
+	private final long timestamp;
 
 	ForumListItem(Forum forum, GroupCount count) {
 		this.forum = forum;
@@ -18,10 +22,11 @@ class ForumListItem {
 		this.timestamp = count.getLatestMsgTime();
 	}
 
-	void addHeader(ForumPostHeader h) {
+	ForumListItem(ForumListItem item, ForumPostHeader h) {
-		postCount++;
+		this.forum = item.forum;
-		if (!h.isRead()) unread++;
+		this.postCount = item.postCount + 1;
-		if (h.getTimestamp() > timestamp) timestamp = h.getTimestamp();
+		this.unread = item.unread + (h.isRead() ? 0 : 1);
+		this.timestamp = Math.max(item.timestamp, h.getTimestamp());
 	}
 
 	Forum getForum() {
@@ -43,4 +48,29 @@ class ForumListItem {
 	int getUnreadCount() {
 		return unread;
 	}
+
+	@Override
+	public int hashCode() {
+		return forum.getId().hashCode();
+	}
+
+	@Override
+	public boolean equals(@Nullable Object o) {
+		return o instanceof ForumListItem && getForum().equals(
+				((ForumListItem) o).getForum());
+	}
+
+	@Override
+	public int compareTo(ForumListItem o) {
+		if (this == o) return 0;
+		// The forum with the newest message comes first
+		long aTime = getTimestamp(), bTime = o.getTimestamp();
+		if (aTime > bTime) return -1;
+		if (aTime < bTime) return 1;
+		// Break ties by forum name
+		String aName = getForum().getName();
+		String bName = o.getForum().getName();
+		return String.CASE_INSENSITIVE_ORDER.compare(aName, bName);
+	}
+
 }

briar-android/src/main/java/org/briarproject/briar/android/forum/ForumListViewModel.java

@@ -0,0 +1,187 @@
+package org.briarproject.briar.android.forum;
+
+import android.app.Application;
+
+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.Transaction;
+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.lifecycle.LifecycleManager;
+import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
+import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
+import org.briarproject.bramble.api.sync.GroupId;
+import org.briarproject.bramble.api.sync.event.GroupAddedEvent;
+import org.briarproject.bramble.api.sync.event.GroupRemovedEvent;
+import org.briarproject.bramble.api.system.AndroidExecutor;
+import org.briarproject.briar.android.viewmodel.DbViewModel;
+import org.briarproject.briar.android.viewmodel.LiveResult;
+import org.briarproject.briar.api.android.AndroidNotificationManager;
+import org.briarproject.briar.api.client.MessageTracker.GroupCount;
+import org.briarproject.briar.api.forum.Forum;
+import org.briarproject.briar.api.forum.ForumManager;
+import org.briarproject.briar.api.forum.ForumPostHeader;
+import org.briarproject.briar.api.forum.ForumSharingManager;
+import org.briarproject.briar.api.forum.event.ForumInvitationRequestReceivedEvent;
+import org.briarproject.briar.api.forum.event.ForumPostReceivedEvent;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import java.util.concurrent.Executor;
+import java.util.logging.Logger;
+
+import javax.inject.Inject;
+
+import androidx.annotation.UiThread;
+import androidx.lifecycle.LiveData;
+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.logDuration;
+import static org.briarproject.bramble.util.LogUtils.logException;
+import static org.briarproject.bramble.util.LogUtils.now;
+import static org.briarproject.briar.api.forum.ForumManager.CLIENT_ID;
+
+@MethodsNotNullByDefault
+@ParametersNotNullByDefault
+class ForumListViewModel extends DbViewModel implements EventListener {
+
+	private static final Logger LOG =
+			getLogger(ForumListViewModel.class.getName());
+
+	private final ForumManager forumManager;
+	private final ForumSharingManager forumSharingManager;
+	private final AndroidNotificationManager notificationManager;
+	private final EventBus eventBus;
+
+	private final MutableLiveData<LiveResult<List<ForumListItem>>> forumItems =
+			new MutableLiveData<>();
+	private final MutableLiveData<Integer> numInvitations =
+			new MutableLiveData<>();
+
+	@Inject
+	ForumListViewModel(Application application,
+			@DatabaseExecutor Executor dbExecutor,
+			LifecycleManager lifecycleManager,
+			TransactionManager db,
+			AndroidExecutor androidExecutor,
+			ForumManager forumManager,
+			ForumSharingManager forumSharingManager,
+			AndroidNotificationManager notificationManager, EventBus eventBus) {
+		super(application, dbExecutor, lifecycleManager, db, androidExecutor);
+		this.forumManager = forumManager;
+		this.forumSharingManager = forumSharingManager;
+		this.notificationManager = notificationManager;
+		this.eventBus = eventBus;
+		this.eventBus.addListener(this);
+	}
+
+	@Override
+	protected void onCleared() {
+		super.onCleared();
+		eventBus.removeListener(this);
+	}
+
+	void clearAllForumPostNotifications() {
+		notificationManager.clearAllForumPostNotifications();
+	}
+
+	void blockAllForumPostNotifications() {
+		notificationManager.blockAllForumPostNotifications();
+	}
+
+	void unblockAllForumPostNotifications() {
+		notificationManager.unblockAllForumPostNotifications();
+	}
+
+	@Override
+	public void eventOccurred(Event e) {
+		if (e instanceof ContactRemovedEvent) {
+			LOG.info("Contact removed, reloading available forums");
+			loadForumInvitations();
+		} else if (e instanceof ForumInvitationRequestReceivedEvent) {
+			LOG.info("Forum invitation received, reloading available forums");
+			loadForumInvitations();
+		} else if (e instanceof GroupAddedEvent) {
+			GroupAddedEvent g = (GroupAddedEvent) e;
+			if (g.getGroup().getClientId().equals(CLIENT_ID)) {
+				LOG.info("Forum added, reloading forums");
+				loadForums();
+			}
+		} else if (e instanceof GroupRemovedEvent) {
+			GroupRemovedEvent g = (GroupRemovedEvent) e;
+			if (g.getGroup().getClientId().equals(CLIENT_ID)) {
+				LOG.info("Forum removed, removing from list");
+				onGroupRemoved(g.getGroup().getId());
+			}
+		} else if (e instanceof ForumPostReceivedEvent) {
+			ForumPostReceivedEvent f = (ForumPostReceivedEvent) e;
+			LOG.info("Forum post added, updating item");
+			onForumPostReceived(f.getGroupId(), f.getHeader());
+		}
+	}
+
+	public void loadForums() {
+		loadList(this::loadForums, forumItems::setValue);
+	}
+
+	@DatabaseExecutor
+	private List<ForumListItem> loadForums(Transaction txn) throws DbException {
+		long start = now();
+		List<ForumListItem> forums = new ArrayList<>();
+		for (Forum f : forumManager.getForums(txn)) {
+			GroupCount count = forumManager.getGroupCount(txn, f.getId());
+			forums.add(new ForumListItem(f, count));
+		}
+		Collections.sort(forums);
+		logDuration(LOG, "Loading forums", start);
+		return forums;
+	}
+
+	@UiThread
+	private void onForumPostReceived(GroupId g, ForumPostHeader header) {
+		List<ForumListItem> list = updateListItems(forumItems,
+				itemToTest -> itemToTest.getForum().getId().equals(g),
+				itemToUpdate -> new ForumListItem(itemToUpdate, header));
+		if (list == null) return;
+		// re-sort as the order of items may have changed
+		Collections.sort(list);
+		forumItems.setValue(new LiveResult<>(list));
+	}
+
+	@UiThread
+	private void onGroupRemoved(GroupId groupId) {
+		List<ForumListItem> list = removeListItems(forumItems, i ->
+				i.getForum().getId().equals(groupId)
+		);
+		if (list == null) return;
+		forumItems.setValue(new LiveResult<>(list));
+	}
+
+	void loadForumInvitations() {
+		runOnDbThread(() -> {
+			try {
+				long start = now();
+				int available = forumSharingManager.getInvitations().size();
+				logDuration(LOG, "Loading available", start);
+				numInvitations.postValue(available);
+			} catch (DbException e) {
+				logException(LOG, WARNING, e);
+			}
+		});
+	}
+
+	LiveData<LiveResult<List<ForumListItem>>> getForumListItems() {
+		return forumItems;
+	}
+
+	LiveData<Integer> getNumInvitations() {
+		return numInvitations;
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/forum/ForumModule.java

@@ -2,13 +2,25 @@ package org.briarproject.briar.android.forum;
 
 import org.briarproject.briar.android.activity.ActivityScope;
 import org.briarproject.briar.android.activity.BaseActivity;
+import org.briarproject.briar.android.viewmodel.ViewModelKey;
 
+import androidx.lifecycle.ViewModel;
+import dagger.Binds;
 import dagger.Module;
 import dagger.Provides;
+import dagger.multibindings.IntoMap;
 
 @Module
 public class ForumModule {
 
+	@Module
+	public interface BindsModule {
+		@Binds
+		@IntoMap
+		@ViewModelKey(ForumListViewModel.class)
+		ViewModel bindForumListViewModel(ForumListViewModel forumListViewModel);
+	}
+
 	@ActivityScope
 	@Provides
 	ForumController provideForumController(BaseActivity activity,

briar-android/src/main/java/org/briarproject/briar/android/forum/ForumPostItem.java

@@ -10,15 +10,15 @@ import javax.annotation.Nullable;
 import javax.annotation.concurrent.NotThreadSafe;
 
 @NotThreadSafe
-class ForumItem extends ThreadItem {
+class ForumPostItem extends ThreadItem {
 
-	ForumItem(ForumPostHeader h, String text) {
+	ForumPostItem(ForumPostHeader h, String text) {
 		super(h.getId(), h.getParentId(), text, h.getTimestamp(), h.getAuthor(),
 				h.getAuthorInfo(), h.isRead());
 	}
 
-	ForumItem(MessageId messageId, @Nullable MessageId parentId, String text,
+	ForumPostItem(MessageId messageId, @Nullable MessageId parentId,
-			long timestamp, Author author, AuthorInfo authorInfo) {
+			String text, long timestamp, Author author, AuthorInfo authorInfo) {
 		super(messageId, parentId, text, timestamp, author, authorInfo, true);
 	}
 

briar-android/src/main/java/org/briarproject/briar/android/forum/ForumViewHolder.java

@@ -0,0 +1,77 @@
+package org.briarproject.briar.android.forum;
+
+import android.content.Context;
+import android.content.Intent;
+import android.view.View;
+import android.view.ViewGroup;
+import android.widget.TextView;
+
+import org.briarproject.briar.R;
+import org.briarproject.briar.android.util.UiUtils;
+import org.briarproject.briar.android.view.TextAvatarView;
+import org.briarproject.briar.api.forum.Forum;
+
+import androidx.recyclerview.widget.RecyclerView;
+
+import static android.view.View.GONE;
+import static android.view.View.VISIBLE;
+import static org.briarproject.briar.android.activity.BriarActivity.GROUP_ID;
+import static org.briarproject.briar.android.activity.BriarActivity.GROUP_NAME;
+
+class ForumViewHolder extends RecyclerView.ViewHolder {
+
+	private final Context ctx;
+	private final ViewGroup layout;
+	private final TextAvatarView avatar;
+	private final TextView name;
+	private final TextView postCount;
+	private final TextView date;
+
+	ForumViewHolder(View v) {
+		super(v);
+		ctx = v.getContext();
+		layout = (ViewGroup) v;
+		avatar = v.findViewById(R.id.avatarView);
+		name = v.findViewById(R.id.forumNameView);
+		postCount = v.findViewById(R.id.postCountView);
+		date = v.findViewById(R.id.dateView);
+	}
+
+	void bind(ForumListItem item) {
+		// Avatar
+		avatar.setText(item.getForum().getName().substring(0, 1));
+		avatar.setBackgroundBytes(item.getForum().getId().getBytes());
+		avatar.setUnreadCount(item.getUnreadCount());
+
+		// Forum Name
+		name.setText(item.getForum().getName());
+
+		// Post Count
+		int count = item.getPostCount();
+		if (count > 0) {
+			postCount.setText(ctx.getResources()
+					.getQuantityString(R.plurals.posts, count, count));
+		} else {
+			postCount.setText(ctx.getString(R.string.no_posts));
+		}
+
+		// Date
+		if (item.isEmpty()) {
+			date.setVisibility(GONE);
+		} else {
+			long timestamp = item.getTimestamp();
+			date.setText(UiUtils.formatDate(ctx, timestamp));
+			date.setVisibility(VISIBLE);
+		}
+
+		// Open Forum on Click
+		layout.setOnClickListener(v -> {
+			Intent i = new Intent(ctx, ForumActivity.class);
+			Forum f = item.getForum();
+			i.putExtra(GROUP_ID, f.getId().getBytes());
+			i.putExtra(GROUP_NAME, f.getName());
+			ctx.startActivity(i);
+		});
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/fragment/BaseFragment.java

@@ -5,7 +5,6 @@ import android.content.Context;
 import android.os.Bundle;
 import android.view.MenuItem;
 
-import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.briar.android.DestroyableContext;
@@ -77,7 +76,7 @@ public abstract class BaseFragment extends Fragment
 		void showNextFragment(BaseFragment f);
 
 		@UiThread
-		void handleDbException(DbException e);
+		void handleException(Exception e);
 	}
 
 	@CallSuper
@@ -100,8 +99,8 @@ public abstract class BaseFragment extends Fragment
 	}
 
 	@UiThread
-	protected void handleDbException(DbException e) {
+	protected void handleException(Exception e) {
-		listener.handleDbException(e);
+		listener.handleException(e);
 	}
 
 }

briar-android/src/main/java/org/briarproject/briar/android/fragment/ScreenFilterDialogFragment.java

@@ -5,6 +5,7 @@ import android.app.Activity;
 import android.app.Dialog;
 import android.content.Context;
 import android.content.DialogInterface;
+import android.content.Intent;
 import android.os.Bundle;
 import android.text.TextUtils;
 import android.view.LayoutInflater;
@@ -28,6 +29,10 @@ import javax.inject.Inject;
 import androidx.appcompat.app.AlertDialog;
 import androidx.fragment.app.DialogFragment;
 
+import static android.os.Build.VERSION.SDK_INT;
+import static android.provider.Settings.ACTION_MANAGE_OVERLAY_PERMISSION;
+import static android.view.View.GONE;
+
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
 public class ScreenFilterDialogFragment extends DialogFragment {
@@ -37,7 +42,7 @@ public class ScreenFilterDialogFragment extends DialogFragment {
 	@Inject
 	ScreenFilterMonitor screenFilterMonitor;
 
-	DismissListener dismissListener = null;
+	private DismissListener dismissListener = null;
 
 	public static ScreenFilterDialogFragment newInstance(
 			Collection<AppDetails> apps) {
@@ -83,10 +88,20 @@ public class ScreenFilterDialogFragment extends DialogFragment {
 		View dialogView = inflater.inflate(R.layout.dialog_screen_filter, null);
 		builder.setView(dialogView);
 		TextView message = dialogView.findViewById(R.id.screen_filter_message);
-		message.setText(getString(R.string.screen_filter_body,
-				TextUtils.join("\n", appNames)));
 		CheckBox allow = dialogView.findViewById(R.id.screen_filter_checkbox);
-		builder.setNeutralButton(R.string.continue_button, (dialog, which) -> {
+		if (SDK_INT <= 29) {
+			message.setText(getString(R.string.screen_filter_body,
+					TextUtils.join("\n", appNames)));
+		} else {
+			message.setText(R.string.screen_filter_body_api_30);
+			allow.setVisibility(GONE);
+			builder.setNeutralButton(R.string.screen_filter_review_apps,
+					(dialog, which) -> {
+						Intent i = new Intent(ACTION_MANAGE_OVERLAY_PERMISSION);
+						startActivity(i);
+					});
+		}
+		builder.setPositiveButton(R.string.continue_button, (dialog, which) -> {
 			if (allow.isChecked()) screenFilterMonitor.allowApps(packageNames);
 			dialog.dismiss();
 		});

briar-android/src/main/java/org/briarproject/briar/android/introduction/ContactChooserFragment.java

@@ -32,7 +32,6 @@ import androidx.annotation.Nullable;
 import androidx.annotation.UiThread;
 import androidx.recyclerview.widget.LinearLayoutManager;
 
-import static java.util.Objects.requireNonNull;
 import static java.util.logging.Level.WARNING;
 import static org.briarproject.bramble.util.LogUtils.logException;
 import static org.briarproject.briar.android.conversation.ConversationActivity.CONTACT_ID;
@@ -84,7 +83,7 @@ public class ContactChooserFragment extends BaseFragment {
 					Contact c2 = item.getContact();
 					showMessageScreen(c1, c2);
 				};
-		adapter = new ContactListAdapter(requireNonNull(getActivity()),
+		adapter = new ContactListAdapter(requireActivity(),
 				onContactClickListener);
 
 		list = contentView.findViewById(R.id.list);
@@ -92,8 +91,7 @@ public class ContactChooserFragment extends BaseFragment {
 		list.setAdapter(adapter);
 		list.setEmptyText(R.string.no_contacts);
 
-		contactId = new ContactId(
+		contactId = new ContactId(requireArguments().getInt(CONTACT_ID));
-				requireNonNull(getArguments()).getInt(CONTACT_ID));
 
 		return contentView;
 	}

briar-android/src/main/java/org/briarproject/briar/android/introduction/IntroductionMessageFragment.java

@@ -39,7 +39,6 @@ import static android.app.Activity.RESULT_OK;
 import static android.view.View.GONE;
 import static android.view.View.VISIBLE;
 import static android.widget.Toast.LENGTH_SHORT;
-import static java.util.Objects.requireNonNull;
 import static java.util.logging.Level.WARNING;
 import static org.briarproject.bramble.util.LogUtils.logException;
 import static org.briarproject.briar.android.util.UiUtils.getContactDisplayName;
@@ -102,7 +101,7 @@ public class IntroductionMessageFragment extends BaseFragment
 		}
 
 		// get contact IDs from fragment arguments
-		Bundle args = requireNonNull(getArguments());
+		Bundle args = requireArguments();
 		int contactId1 = args.getInt(CONTACT_ID_1, -1);
 		int contactId2 = args.getInt(CONTACT_ID_2, -1);
 		if (contactId1 == -1 || contactId2 == -1) {

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() {
+	private void showErrorFragment() {
-		String errorMsg = getString(R.string.connection_error_explanation);
+		showNextFragment(new ContactExchangeErrorFragment());
-		BaseFragment f = ContactExchangeErrorFragment.newInstance(errorMsg);
-		showNextFragment(f);
 	}
 }

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;
@@ -9,16 +10,16 @@ import android.widget.TextView;
 
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
-import org.briarproject.bramble.api.system.AndroidExecutor;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.activity.ActivityComponent;
 import org.briarproject.briar.android.fragment.BaseFragment;
 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
@@ -37,9 +38,6 @@ public class ContactExchangeErrorFragment extends BaseFragment {
 		return f;
 	}
 
-	@Inject
-	AndroidExecutor androidExecutor;
-
 	@Override
 	public String getUniqueTag() {
 		return TAG;
@@ -58,13 +56,12 @@ 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) {
+		String errorMessage = args == null ? null : args.getString(ERROR_MSG);
-			throw new IllegalArgumentException("Use newInstance()");
+		if (errorMessage == null) explanation.setVisibility(GONE);
-		}
+		else explanation.setText(args.getString(ERROR_MSG));
-		explanation.setText(args.getString(ERROR_MSG));
 
 		// make feedback link clickable
 		TextView sendFeedback = v.findViewById(R.id.sendFeedback);
@@ -73,7 +70,11 @@ 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());
@@ -81,8 +82,8 @@ public class ContactExchangeErrorFragment extends BaseFragment {
 	}
 
 	private void triggerFeedback() {
+		UiUtils.triggerFeedback(requireContext());
 		finish();
-		UiUtils.triggerFeedback(androidExecutor);
 	}
 
 }

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 ||
+				(SDK_INT < 23 || locationPermission == Permission.GRANTED ||
-						locationPermission == Permission.PERMANENTLY_DENIED);
+						!isBluetoothSupported());
+	}
+
+	private boolean isBluetoothSupported() {
+		return bt != null && bluetoothPlugin != null;
 	}
 
 	private boolean isWifiReady() {
-		Plugin p = pluginManager.getPlugin(LanTcpConstants.ID);
+		if (wifiPlugin == null) return true; // Continue without wifi
-		if (p == null) return true; // Continue without wifi
+		State state = wifiPlugin.getState();
-		State state = p.getState();
 		// Wait for plugin to become enabled
 		return state == ACTIVE || state == INACTIVE;
 	}
 
 	private boolean isBluetoothReady() {
-		if (bluetoothDecision == BluetoothDecision.UNKNOWN ||
+		if (!isBluetoothSupported()) {
-				bluetoothDecision == BluetoothDecision.WAITING) {
-			// Wait for decision
-			return false;
-		}
-		if (bluetoothDecision == BluetoothDecision.NO_ADAPTER
-				|| bluetoothDecision == BluetoothDecision.REFUSED) {
 			// Continue without Bluetooth
 			return true;
 		}
-		BluetoothAdapter bt = BluetoothAdapter.getDefaultAdapter();
+		if (bluetoothDecision == BluetoothDecision.UNKNOWN ||
-		if (bt == null) return true; // Continue without Bluetooth
+				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 (wifiPlugin == null) return false;
-		if (p == null) return false;
+		State state = wifiPlugin.getState();
-		State state = p.getState();
 		return state == STARTING_STOPPING || state == DISABLED;
 	}
 
 	private void requestBluetoothDiscoverable() {
-		BluetoothAdapter bt = BluetoothAdapter.getDefaultAdapter();
+		if (!isBluetoothSupported()) {
-		if (bt == null) {
 			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 (!isBluetoothSupported()) return false;
-		if (p == null) return false;
+		State state = bluetoothPlugin.getState();
-		State state = p.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);
+			showDenialDialog(R.string.permission_camera_title,
-			builder.setTitle(R.string.permission_camera_title);
+					R.string.permission_camera_denied_body);
-			builder.setMessage(R.string.permission_camera_denied_body);
+			return false;
-			builder.setPositiveButton(R.string.ok,
+		}
-					UiUtils.getGoToSettingsListener(this));
+		if (isBluetoothSupported() &&
-			builder.setNegativeButton(R.string.cancel,
+				locationPermission == Permission.PERMANENTLY_DENIED) {
-					(dialog, which) -> supportFinishAfterTransition());
+			showDenialDialog(R.string.permission_location_title,
-			builder.show();
+					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,
+		String[] permissions;
-				new String[] {CAMERA, ACCESS_FINE_LOCATION},
+		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)) {
+		if (isBluetoothSupported()) {
-			locationPermission = Permission.GRANTED;
+			if (gotPermission(ACCESS_FINE_LOCATION, permissions,
-		} else if (shouldShowRationale(ACCESS_FINE_LOCATION)) {
+					grantResults)) {
-			locationPermission = Permission.SHOW_RATIONALE;
+				locationPermission = Permission.GRANTED;
-		} else {
+			} else if (shouldShowRationale(ACCESS_FINE_LOCATION)) {
-			locationPermission = Permission.PERMANENTLY_DENIED;
+				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/keyagreement/KeyAgreementFragment.java

@@ -54,7 +54,6 @@ import static android.view.View.VISIBLE;
 import static android.view.ViewGroup.LayoutParams.MATCH_PARENT;
 import static android.widget.LinearLayout.HORIZONTAL;
 import static android.widget.Toast.LENGTH_LONG;
-import static java.util.Objects.requireNonNull;
 import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
 import static org.briarproject.bramble.util.LogUtils.logException;
@@ -67,6 +66,7 @@ public class KeyAgreementFragment extends BaseEventFragment
 	static final String TAG = KeyAgreementFragment.class.getName();
 
 	private static final Logger LOG = Logger.getLogger(TAG);
+	@SuppressWarnings("CharsetObjectCanBeUsed") // Requires minSdkVersion >= 19
 	private static final Charset ISO_8859_1 = Charset.forName("ISO-8859-1");
 
 	@Inject
@@ -138,8 +138,7 @@ public class KeyAgreementFragment extends BaseEventFragment
 	@Override
 	public void onActivityCreated(@Nullable Bundle savedInstanceState) {
 		super.onActivityCreated(savedInstanceState);
-		requireNonNull(getActivity())
+		requireActivity().setRequestedOrientation(SCREEN_ORIENTATION_NOSENSOR);
-				.setRequestedOrientation(SCREEN_ORIENTATION_NOSENSOR);
 		cameraView.setPreviewConsumer(new QrCodeDecoder(this));
 	}
 

briar-android/src/main/java/org/briarproject/briar/android/login/OpenDatabaseFragment.java

@@ -16,6 +16,7 @@ import org.briarproject.briar.android.fragment.BaseFragment;
 import javax.inject.Inject;
 
 import androidx.annotation.Nullable;
+import androidx.lifecycle.LifecycleOwner;
 import androidx.lifecycle.ViewModelProvider;
 import androidx.lifecycle.ViewModelProviders;
 
@@ -51,7 +52,8 @@ public class OpenDatabaseFragment extends BaseFragment {
 
 		StartupViewModel viewModel = ViewModelProviders.of(requireActivity(),
 				viewModelFactory).get(StartupViewModel.class);
-		viewModel.getState().observe(this, this::onStateChanged);
+		LifecycleOwner owner = getViewLifecycleOwner();
+		viewModel.getState().observe(owner, this::onStateChanged);
 
 		return v;
 	}

briar-android/src/main/java/org/briarproject/briar/android/login/PasswordFragment.java

@@ -23,6 +23,7 @@ import javax.annotation.Nullable;
 import javax.inject.Inject;
 
 import androidx.appcompat.app.AlertDialog;
+import androidx.lifecycle.LifecycleOwner;
 import androidx.lifecycle.ViewModelProvider;
 import androidx.lifecycle.ViewModelProviders;
 
@@ -67,7 +68,8 @@ public class PasswordFragment extends BaseFragment implements TextWatcher {
 		viewModel = ViewModelProviders.of(requireActivity(), viewModelFactory)
 				.get(StartupViewModel.class);
 
-		viewModel.getPasswordValidated().observeEvent(this, result -> {
+		LifecycleOwner owner = getViewLifecycleOwner();
+		viewModel.getPasswordValidated().observeEvent(owner, result -> {
 			if (result != SUCCESS) onPasswordInvalid(result);
 		});
 

briar-android/src/main/java/org/briarproject/briar/android/navdrawer/NavDrawerActivity.java

@@ -17,7 +17,6 @@ import android.widget.TextView;
 import com.google.android.material.navigation.NavigationView;
 import com.google.android.material.navigation.NavigationView.OnNavigationItemSelectedListener;
 
-import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.lifecycle.LifecycleManager;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
@@ -365,7 +364,7 @@ public class NavDrawerActivity extends BriarActivity implements
 	}
 
 	@Override
-	public void handleDbException(DbException e) {
+	public void handleException(Exception e) {
 		// Do nothing for now
 	}
 

briar-android/src/main/java/org/briarproject/briar/android/navdrawer/NavDrawerViewModel.java

@@ -4,9 +4,13 @@ import android.app.Application;
 
 import org.briarproject.bramble.api.db.DatabaseExecutor;
 import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.db.TransactionManager;
+import org.briarproject.bramble.api.lifecycle.LifecycleManager;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.settings.Settings;
 import org.briarproject.bramble.api.settings.SettingsManager;
+import org.briarproject.bramble.api.system.AndroidExecutor;
+import org.briarproject.briar.android.viewmodel.DbViewModel;
 
 import java.util.concurrent.Executor;
 import java.util.logging.Logger;
@@ -14,7 +18,6 @@ import java.util.logging.Logger;
 import javax.inject.Inject;
 
 import androidx.annotation.UiThread;
-import androidx.lifecycle.AndroidViewModel;
 import androidx.lifecycle.LiveData;
 import androidx.lifecycle.MutableLiveData;
 
@@ -28,7 +31,7 @@ import static org.briarproject.briar.android.settings.SettingsFragment.SETTINGS_
 import static org.briarproject.briar.android.util.UiUtils.needsDozeWhitelisting;
 
 @NotNullByDefault
-public class NavDrawerViewModel extends AndroidViewModel {
+public class NavDrawerViewModel extends DbViewModel {
 
 	private static final Logger LOG =
 			getLogger(NavDrawerViewModel.class.getName());
@@ -37,8 +40,6 @@ public class NavDrawerViewModel extends AndroidViewModel {
 	private static final String SHOW_TRANSPORTS_ONBOARDING =
 			"showTransportsOnboarding";
 
-	@DatabaseExecutor
-	private final Executor dbExecutor;
 	private final SettingsManager settingsManager;
 
 	private final MutableLiveData<Boolean> showExpiryWarning =
@@ -49,10 +50,13 @@ public class NavDrawerViewModel extends AndroidViewModel {
 			new MutableLiveData<>();
 
 	@Inject
-	NavDrawerViewModel(Application app, @DatabaseExecutor Executor dbExecutor,
+	NavDrawerViewModel(Application app,
+			@DatabaseExecutor Executor dbExecutor,
+			LifecycleManager lifecycleManager,
+			TransactionManager db,
+			AndroidExecutor androidExecutor,
 			SettingsManager settingsManager) {
-		super(app);
+		super(app, dbExecutor, lifecycleManager, db, androidExecutor);
-		this.dbExecutor = dbExecutor;
 		this.settingsManager = settingsManager;
 	}
 
@@ -62,7 +66,7 @@ public class NavDrawerViewModel extends AndroidViewModel {
 
 	@UiThread
 	void checkExpiryWarning() {
-		dbExecutor.execute(() -> {
+		runOnDbThread(() -> {
 			try {
 				Settings settings =
 						settingsManager.getSettings(SETTINGS_NAMESPACE);
@@ -97,7 +101,7 @@ public class NavDrawerViewModel extends AndroidViewModel {
 	@UiThread
 	void expiryWarningDismissed() {
 		showExpiryWarning.setValue(false);
-		dbExecutor.execute(() -> {
+		runOnDbThread(() -> {
 			try {
 				Settings settings = new Settings();
 				int date = (int) (System.currentTimeMillis() / 1000L);
@@ -120,7 +124,7 @@ public class NavDrawerViewModel extends AndroidViewModel {
 			shouldAskForDozeWhitelisting.setValue(false);
 			return;
 		}
-		dbExecutor.execute(() -> {
+		runOnDbThread(() -> {
 			try {
 				Settings settings =
 						settingsManager.getSettings(SETTINGS_NAMESPACE);
@@ -141,7 +145,7 @@ public class NavDrawerViewModel extends AndroidViewModel {
 	@UiThread
 	void checkTransportsOnboarding() {
 		if (showTransportsOnboarding.getValue() != null) return;
-		dbExecutor.execute(() -> {
+		runOnDbThread(() -> {
 			try {
 				Settings settings =
 						settingsManager.getSettings(SETTINGS_NAMESPACE);
@@ -157,7 +161,7 @@ public class NavDrawerViewModel extends AndroidViewModel {
 	@UiThread
 	void transportsOnboardingShown() {
 		showTransportsOnboarding.setValue(false);
-		dbExecutor.execute(() -> {
+		runOnDbThread(() -> {
 			try {
 				Settings settings = new Settings();
 				settings.putBoolean(SHOW_TRANSPORTS_ONBOARDING, false);

briar-android/src/main/java/org/briarproject/briar/android/navdrawer/PluginViewModel.java

@@ -9,9 +9,11 @@ import android.content.IntentFilter;
 
 import org.briarproject.bramble.api.db.DatabaseExecutor;
 import org.briarproject.bramble.api.db.DbException;
+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.lifecycle.LifecycleManager;
 import org.briarproject.bramble.api.network.NetworkManager;
 import org.briarproject.bramble.api.network.NetworkStatus;
 import org.briarproject.bramble.api.network.event.NetworkStatusEvent;
@@ -27,6 +29,8 @@ import org.briarproject.bramble.api.plugin.event.TransportStateEvent;
 import org.briarproject.bramble.api.settings.Settings;
 import org.briarproject.bramble.api.settings.SettingsManager;
 import org.briarproject.bramble.api.settings.event.SettingsUpdatedEvent;
+import org.briarproject.bramble.api.system.AndroidExecutor;
+import org.briarproject.briar.android.viewmodel.DbViewModel;
 
 import java.util.concurrent.Executor;
 import java.util.logging.Logger;
@@ -34,7 +38,6 @@ import java.util.logging.Logger;
 import javax.inject.Inject;
 
 import androidx.annotation.Nullable;
-import androidx.lifecycle.AndroidViewModel;
 import androidx.lifecycle.LiveData;
 import androidx.lifecycle.MutableLiveData;
 
@@ -51,13 +54,12 @@ import static org.briarproject.bramble.util.LogUtils.logException;
 import static org.briarproject.bramble.util.LogUtils.now;
 
 @NotNullByDefault
-public class PluginViewModel extends AndroidViewModel implements EventListener {
+public class PluginViewModel extends DbViewModel implements EventListener {
 
 	private static final Logger LOG =
 			getLogger(PluginViewModel.class.getName());
 
 	private final Application app;
-	private final Executor dbExecutor;
 	private final SettingsManager settingsManager;
 	private final PluginManager pluginManager;
 	private final EventBus eventBus;
@@ -85,11 +87,12 @@ public class PluginViewModel extends AndroidViewModel implements EventListener {
 
 	@Inject
 	PluginViewModel(Application app, @DatabaseExecutor Executor dbExecutor,
-			SettingsManager settingsManager, PluginManager pluginManager,
+			LifecycleManager lifecycleManager, TransactionManager db,
-			EventBus eventBus, NetworkManager networkManager) {
+			AndroidExecutor androidExecutor, SettingsManager settingsManager,
-		super(app);
+			PluginManager pluginManager, EventBus eventBus,
+			NetworkManager networkManager) {
+		super(app, dbExecutor, lifecycleManager, db, androidExecutor);
 		this.app = app;
-		this.dbExecutor = dbExecutor;
 		this.settingsManager = settingsManager;
 		this.pluginManager = pluginManager;
 		this.eventBus = eventBus;
@@ -182,7 +185,7 @@ public class PluginViewModel extends AndroidViewModel implements EventListener {
 	}
 
 	private void loadSettings() {
-		dbExecutor.execute(() -> {
+		runOnDbThread(() -> {
 			try {
 				boolean tor = isPluginEnabled(TorConstants.ID,
 						TorConstants.DEFAULT_PREF_PLUGIN_ENABLE);
@@ -219,7 +222,7 @@ public class PluginViewModel extends AndroidViewModel implements EventListener {
 	}
 
 	private void mergeSettings(Settings s, String namespace) {
-		dbExecutor.execute(() -> {
+		runOnDbThread(() -> {
 			try {
 				long start = now();
 				settingsManager.mergeSettings(s, namespace);
@@ -235,8 +238,7 @@ public class PluginViewModel extends AndroidViewModel implements EventListener {
 		@Override
 		public void onReceive(Context context, Intent intent) {
 			int state = intent.getIntExtra(EXTRA_STATE, 0);
-			if (state == STATE_ON) bluetoothTurnedOn.postValue(true);
+			bluetoothTurnedOn.postValue(state == STATE_ON);
-			else bluetoothTurnedOn.postValue(false);
 		}
 	}
 }

briar-android/src/main/java/org/briarproject/briar/android/panic/PanicPreferencesFragment.java

@@ -82,6 +82,7 @@ public class PanicPreferencesFragment extends PreferenceFragmentCompat
 		entries.add(0, getString(R.string.panic_app_setting_none));
 		entryValues.add(0, PACKAGE_NAME_NONE);
 
+		// only info.guardianproject.ripple is whitelisted in manifest
 		for (ResolveInfo resolveInfo : PanicResponder.resolveTriggerApps(pm)) {
 			if (resolveInfo.activityInfo == null)
 				continue;

briar-android/src/main/java/org/briarproject/briar/android/privategroup/conversation/GroupActivity.java

@@ -106,7 +106,7 @@ public class GroupActivity extends
 
 					@Override
 					public void onExceptionUi(DbException exception) {
-						handleDbException(exception);
+						handleException(exception);
 					}
 				});
 	}
@@ -125,7 +125,7 @@ public class GroupActivity extends
 
 					@Override
 					public void onExceptionUi(DbException exception) {
-						handleDbException(exception);
+						handleException(exception);
 					}
 				});
 	}
@@ -264,7 +264,7 @@ public class GroupActivity extends
 					// GroupRemovedEvent being fired
 					@Override
 					public void onExceptionUi(DbException exception) {
-						handleDbException(exception);
+						handleException(exception);
 					}
 				});
 	}

briar-android/src/main/java/org/briarproject/briar/android/privategroup/creation/CreateGroupActivity.java

@@ -51,7 +51,7 @@ public class CreateGroupActivity extends BriarActivity
 
 					@Override
 					public void onExceptionUi(DbException exception) {
-						handleDbException(exception);
+						handleException(exception);
 					}
 				});
 	}

briar-android/src/main/java/org/briarproject/briar/android/privategroup/creation/GroupInviteActivity.java

@@ -69,7 +69,7 @@ public class GroupInviteActivity extends ContactSelectorActivity
 					@Override
 					public void onExceptionUi(DbException exception) {
 						setResult(RESULT_CANCELED);
-						handleDbException(exception);
+						handleException(exception);
 					}
 				});
 	}

briar-android/src/main/java/org/briarproject/briar/android/privategroup/creation/GroupInviteFragment.java

@@ -15,7 +15,6 @@ import javax.inject.Inject;
 
 import androidx.annotation.Nullable;
 
-import static java.util.Objects.requireNonNull;
 import static org.briarproject.briar.android.activity.BriarActivity.GROUP_ID;
 
 @MethodsNotNullByDefault
@@ -43,7 +42,7 @@ public class GroupInviteFragment extends ContactSelectorFragment {
 	@Override
 	public void onCreate(@Nullable Bundle savedInstanceState) {
 		super.onCreate(savedInstanceState);
-		requireNonNull(getActivity()).setTitle(R.string.groups_invite_members);
+		requireActivity().setTitle(R.string.groups_invite_members);
 	}
 
 	@Override

briar-android/src/main/java/org/briarproject/briar/android/privategroup/list/GroupItem.java

@@ -8,15 +8,19 @@ import org.briarproject.briar.api.client.MessageTracker.GroupCount;
 import org.briarproject.briar.api.privategroup.GroupMessageHeader;
 import org.briarproject.briar.api.privategroup.PrivateGroup;
 
-// This class is not thread-safe
+import javax.annotation.concurrent.Immutable;
+
+import androidx.annotation.Nullable;
+
+@Immutable
 @NotNullByDefault
-class GroupItem {
+class GroupItem implements Comparable<GroupItem> {
 
 	private final PrivateGroup privateGroup;
 	private final AuthorInfo authorInfo;
-	private int messageCount, unreadCount;
+	private final int messageCount, unreadCount;
-	private long timestamp;
+	private final long timestamp;
-	private boolean dissolved;
+	private final boolean dissolved;
 
 	GroupItem(PrivateGroup privateGroup, AuthorInfo authorInfo,
 			GroupCount count, boolean dissolved) {
@@ -28,18 +32,22 @@ class GroupItem {
 		this.dissolved = dissolved;
 	}
 
-	void addMessageHeader(GroupMessageHeader header) {
+	GroupItem(GroupItem item, GroupMessageHeader header) {
-		messageCount++;
+		this.privateGroup = item.privateGroup;
-		if (header.getTimestamp() > timestamp) {
+		this.authorInfo = item.authorInfo;
-			timestamp = header.getTimestamp();
+		this.messageCount = item.messageCount + 1;
-		}
+		this.unreadCount = item.unreadCount + (header.isRead() ? 0 : 1);
-		if (!header.isRead()) {
+		this.timestamp = Math.max(header.getTimestamp(), item.timestamp);
-			unreadCount++;
+		this.dissolved = item.dissolved;
-		}
 	}
 
-	PrivateGroup getPrivateGroup() {
+	GroupItem(GroupItem item, boolean isDissolved) {
-		return privateGroup;
+		this.privateGroup = item.privateGroup;
+		this.authorInfo = item.authorInfo;
+		this.messageCount = item.messageCount;
+		this.unreadCount = item.unreadCount;
+		this.timestamp = item.timestamp;
+		this.dissolved = isDissolved;
 	}
 
 	GroupId getId() {
@@ -78,8 +86,27 @@ class GroupItem {
 		return dissolved;
 	}
 
-	void setDissolved() {
+	@Override
-		dissolved = true;
+	public int hashCode() {
+		return getId().hashCode();
 	}
 
+	@Override
+	public boolean equals(@Nullable Object o) {
+		return o instanceof GroupItem &&
+				getId().equals(((GroupItem) o).getId());
+	}
+
+	@Override
+	public int compareTo(GroupItem o) {
+		if (this == o) return 0;
+		// The group with the latest message comes first
+		long aTime = getTimestamp(), bTime = o.getTimestamp();
+		if (aTime > bTime) return -1;
+		if (aTime < bTime) return 1;
+		// Break ties by group name
+		String aName = getName();
+		String bName = o.getName();
+		return String.CASE_INSENSITIVE_ORDER.compare(aName, bName);
+	}
 }