DO NOT MERGE: Return fake image attachements in MessagingManager

Update memberlists while they are open

Closes #875

See merge request briar/briar!1048

.idea/codeStyles/Project.xml

@@ -39,31 +39,6 @@
     <JetCodeStyleSettings>
       <option name="CODE_STYLE_DEFAULTS" value="KOTLIN_OFFICIAL" />
     </JetCodeStyleSettings>
-    <Objective-C-extensions>
-      <file>
-        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Import" />
-        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Macro" />
-        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Typedef" />
-        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Enum" />
-        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Constant" />
-        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Global" />
-        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Struct" />
-        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="FunctionPredecl" />
-        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Function" />
-      </file>
-      <class>
-        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Property" />
-        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="Synthesize" />
-        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="InitMethod" />
-        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="StaticMethod" />
-        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="InstanceMethod" />
-        <option name="com.jetbrains.cidr.lang.util.OCDeclarationKind" value="DeallocMethod" />
-      </class>
-      <extensions>
-        <pair source="cpp" header="h" fileNamingConvention="NONE" />
-        <pair source="c" header="h" fileNamingConvention="NONE" />
-      </extensions>
-    </Objective-C-extensions>
     <XML>
       <option name="XML_LEGACY_SETTINGS_IMPORTED" value="true" />
     </XML>

bramble-android/build.gradle

@@ -30,8 +30,8 @@ configurations {
 
 dependencies {
 	implementation project(path: ':bramble-core', configuration: 'default')
-	tor 'org.briarproject:tor-android:0.3.4.8@zip'
+	tor 'org.briarproject:tor-android:0.3.5.8@zip'
-	tor 'org.briarproject:obfs4proxy-android:0.0.7@zip'
+	tor 'org.briarproject:obfs4proxy-android:0.0.9@zip'
 
 	annotationProcessor 'com.google.dagger:dagger-compiler:2.19'
 

bramble-android/witness.gradle

@@ -68,8 +68,8 @@ dependencyVerification {
         'org.beanshell:bsh:1.3.0:bsh-1.3.0.jar:9b04edc75d19db54f1b4e8b5355e9364384c6cf71eb0a1b9724c159d779879f8',
         'org.bouncycastle:bcpkix-jdk15on:1.56:bcpkix-jdk15on-1.56.jar:7043dee4e9e7175e93e0b36f45b1ec1ecb893c5f755667e8b916eb8dd201c6ca',
         'org.bouncycastle:bcprov-jdk15on:1.56:bcprov-jdk15on-1.56.jar:963e1ee14f808ffb99897d848ddcdb28fa91ddda867eb18d303e82728f878349',
-        'org.briarproject:obfs4proxy-android:0.0.7:obfs4proxy-android-0.0.7.zip:abdfb5d889d848de9bf214f9276abbf454808a505b870819eccc9a9e985bf617',
+        'org.briarproject:obfs4proxy-android:0.0.9:obfs4proxy-android-0.0.9.zip:9b7e9181535ea8d8bbe8ae6338e08cf4c5fc1e357a779393e0ce49586d459ae0',
-        'org.briarproject:tor-android:0.3.4.8:tor-android-0.3.4.8.zip:989a0352d9d8d8172cd6c2137654e165e5d2beb10ed1211bab3814e224ad1926',
+        'org.briarproject:tor-android:0.3.5.8:tor-android-0.3.5.8.zip:42a13a6f185be1a62f42e3f30ce66a3c099ac5ec890a65e7593111b65b44a54a',
         'org.checkerframework:checker-compat-qual:2.5.3:checker-compat-qual-2.5.3.jar:d76b9afea61c7c082908023f0cbc1427fab9abd2df915c8b8a3e7a509bccbc6d',
         'org.codehaus.groovy:groovy-all:2.4.12:groovy-all-2.4.12.jar:6a56af4bd48903d56bec62821876cadefafd007360cc6bd0d8f7aa8d72b38be4',
         'org.codehaus.mojo:animal-sniffer-annotations:1.14:animal-sniffer-annotations-1.14.jar:2068320bd6bad744c3673ab048f67e30bef8f518996fa380033556600669905d',

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

@@ -1,20 +0,0 @@
-package org.briarproject.bramble.api.contact;
-
-import org.briarproject.bramble.api.identity.Author;
-import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-
-@NotNullByDefault
-public interface ContactExchangeListener {
-
-	void contactExchangeSucceeded(Author remoteAuthor);
-
-	/**
-	 * The exchange failed because the contact already exists.
-	 */
-	void duplicateContact(Author remoteAuthor);
-
-	/**
-	 * A general failure.
-	 */
-	void contactExchangeFailed();
-}

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

@@ -41,8 +41,7 @@ public interface ContactExchangeTask {
 	/**
 	 * Exchanges contact information with a remote peer.
 	 */
-	void startExchange(ContactExchangeListener listener,
+	void startExchange(LocalAuthor localAuthor, SecretKey masterSecret,
-			LocalAuthor localAuthor, SecretKey masterSecret,
 			DuplexTransportConnection conn, TransportId transportId,
 			boolean alice);
 }

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

@@ -0,0 +1,32 @@
+package org.briarproject.bramble.api.contact.event;
+
+import org.briarproject.bramble.api.event.Event;
+import org.briarproject.bramble.api.identity.Author;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import javax.annotation.Nullable;
+
+@NotNullByDefault
+public class ContactExchangeFailedEvent extends Event {
+
+	@Nullable
+	private final Author duplicateRemoteAuthor;
+
+	public ContactExchangeFailedEvent(@Nullable Author duplicateRemoteAuthor) {
+		this.duplicateRemoteAuthor = duplicateRemoteAuthor;
+	}
+
+	public ContactExchangeFailedEvent() {
+		this(null);
+	}
+
+	@Nullable
+	public Author getDuplicateRemoteAuthor() {
+		return duplicateRemoteAuthor;
+	}
+
+	public boolean wasDuplicateContact() {
+		return duplicateRemoteAuthor != null;
+	}
+
+}

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

@@ -0,0 +1,20 @@
+package org.briarproject.bramble.api.contact.event;
+
+import org.briarproject.bramble.api.event.Event;
+import org.briarproject.bramble.api.identity.Author;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+@NotNullByDefault
+public class ContactExchangeSucceededEvent extends Event {
+
+	private final Author remoteAuthor;
+
+	public ContactExchangeSucceededEvent(Author remoteAuthor) {
+		this.remoteAuthor = remoteAuthor;
+	}
+
+	public Author getRemoteAuthor() {
+		return remoteAuthor;
+	}
+
+}

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

@@ -2,10 +2,11 @@ package org.briarproject.bramble.contact;
 
 import org.briarproject.bramble.api.FormatException;
 import org.briarproject.bramble.api.client.ClientHelper;
-import org.briarproject.bramble.api.contact.ContactExchangeListener;
 import org.briarproject.bramble.api.contact.ContactExchangeTask;
 import org.briarproject.bramble.api.contact.ContactId;
 import org.briarproject.bramble.api.contact.ContactManager;
+import org.briarproject.bramble.api.contact.event.ContactExchangeFailedEvent;
+import org.briarproject.bramble.api.contact.event.ContactExchangeSucceededEvent;
 import org.briarproject.bramble.api.crypto.CryptoComponent;
 import org.briarproject.bramble.api.crypto.SecretKey;
 import org.briarproject.bramble.api.data.BdfDictionary;
@@ -13,6 +14,7 @@ import org.briarproject.bramble.api.data.BdfList;
 import org.briarproject.bramble.api.db.ContactExistsException;
 import org.briarproject.bramble.api.db.DatabaseComponent;
 import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.event.EventBus;
 import org.briarproject.bramble.api.identity.Author;
 import org.briarproject.bramble.api.identity.LocalAuthor;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
@@ -63,6 +65,7 @@ class ContactExchangeTaskImpl extends Thread implements ContactExchangeTask {
 	private final ClientHelper clientHelper;
 	private final RecordReaderFactory recordReaderFactory;
 	private final RecordWriterFactory recordWriterFactory;
+	private final EventBus eventBus;
 	private final Clock clock;
 	private final ConnectionManager connectionManager;
 	private final ContactManager contactManager;
@@ -71,7 +74,6 @@ class ContactExchangeTaskImpl extends Thread implements ContactExchangeTask {
 	private final StreamReaderFactory streamReaderFactory;
 	private final StreamWriterFactory streamWriterFactory;
 
-	private volatile ContactExchangeListener listener;
 	private volatile LocalAuthor localAuthor;
 	private volatile DuplexTransportConnection conn;
 	private volatile TransportId transportId;
@@ -81,8 +83,9 @@ class ContactExchangeTaskImpl extends Thread implements ContactExchangeTask {
 	@Inject
 	ContactExchangeTaskImpl(DatabaseComponent db, ClientHelper clientHelper,
 			RecordReaderFactory recordReaderFactory,
-			RecordWriterFactory recordWriterFactory, Clock clock,
+			RecordWriterFactory recordWriterFactory, EventBus eventBus,
-			ConnectionManager connectionManager, ContactManager contactManager,
+			Clock clock, ConnectionManager connectionManager,
+			ContactManager contactManager,
 			TransportPropertyManager transportPropertyManager,
 			CryptoComponent crypto, StreamReaderFactory streamReaderFactory,
 			StreamWriterFactory streamWriterFactory) {
@@ -90,6 +93,7 @@ class ContactExchangeTaskImpl extends Thread implements ContactExchangeTask {
 		this.clientHelper = clientHelper;
 		this.recordReaderFactory = recordReaderFactory;
 		this.recordWriterFactory = recordWriterFactory;
+		this.eventBus = eventBus;
 		this.clock = clock;
 		this.connectionManager = connectionManager;
 		this.contactManager = contactManager;
@@ -100,11 +104,9 @@ class ContactExchangeTaskImpl extends Thread implements ContactExchangeTask {
 	}
 
 	@Override
-	public void startExchange(ContactExchangeListener listener,
+	public void startExchange(LocalAuthor localAuthor, SecretKey masterSecret,
-			LocalAuthor localAuthor, SecretKey masterSecret,
 			DuplexTransportConnection conn, TransportId transportId,
 			boolean alice) {
-		this.listener = listener;
 		this.localAuthor = localAuthor;
 		this.conn = conn;
 		this.transportId = transportId;
@@ -123,8 +125,8 @@ class ContactExchangeTaskImpl extends Thread implements ContactExchangeTask {
 			out = conn.getWriter().getOutputStream();
 		} catch (IOException e) {
 			logException(LOG, WARNING, e);
-			listener.contactExchangeFailed();
 			tryToClose(conn);
+			eventBus.broadcast(new ContactExchangeFailedEvent());
 			return;
 		}
 
@@ -134,7 +136,7 @@ class ContactExchangeTaskImpl extends Thread implements ContactExchangeTask {
 			localProperties = transportPropertyManager.getLocalProperties();
 		} catch (DbException e) {
 			logException(LOG, WARNING, e);
-			listener.contactExchangeFailed();
+			eventBus.broadcast(new ContactExchangeFailedEvent());
 			tryToClose(conn);
 			return;
 		}
@@ -196,7 +198,7 @@ class ContactExchangeTaskImpl extends Thread implements ContactExchangeTask {
 			}
 		} catch (IOException e) {
 			logException(LOG, WARNING, e);
-			listener.contactExchangeFailed();
+			eventBus.broadcast(new ContactExchangeFailedEvent());
 			tryToClose(conn);
 			return;
 		}
@@ -204,7 +206,7 @@ class ContactExchangeTaskImpl extends Thread implements ContactExchangeTask {
 		// Verify the contact's signature
 		if (!verify(remoteInfo.author, remoteNonce, remoteInfo.signature)) {
 			LOG.warning("Invalid signature");
-			listener.contactExchangeFailed();
+			eventBus.broadcast(new ContactExchangeFailedEvent());
 			tryToClose(conn);
 			return;
 		}
@@ -221,15 +223,17 @@ class ContactExchangeTaskImpl extends Thread implements ContactExchangeTask {
 					conn);
 			// Pseudonym exchange succeeded
 			LOG.info("Pseudonym exchange succeeded");
-			listener.contactExchangeSucceeded(remoteInfo.author);
+			eventBus.broadcast(
+					new ContactExchangeSucceededEvent(remoteInfo.author));
 		} catch (ContactExistsException e) {
 			logException(LOG, WARNING, e);
 			tryToClose(conn);
-			listener.duplicateContact(remoteInfo.author);
+			eventBus.broadcast(
+					new ContactExchangeFailedEvent(remoteInfo.author));
 		} catch (DbException e) {
 			logException(LOG, WARNING, e);
 			tryToClose(conn);
-			listener.contactExchangeFailed();
+			eventBus.broadcast(new ContactExchangeFailedEvent());
 		}
 	}
 

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

@@ -17,16 +17,24 @@ public interface CircumventionProvider {
 	String[] BLOCKED = {"CN", "IR", "EG", "BY", "TR", "SY", "VE"};
 
 	/**
-	 * Countries where vanilla bridge connection are likely to work.
+	 * Countries where obfs4 bridge connection are likely to work.
 	 * Should be a subset of {@link #BLOCKED}.
 	 */
-	String[] BRIDGES = { "EG", "BY", "TR", "SY", "VE" };
+	String[] BRIDGES = { "CN", "IR", "EG", "BY", "TR", "SY", "VE" };
+
+	/**
+	 * Countries where obfs4 bridges won't work and meek is needed.
+	 * Should be a subset of {@link #BRIDGES}.
+	 */
+	String[] NEEDS_MEEK = {"CN", "IR"};
 
 	boolean isTorProbablyBlocked(String countryCode);
 
 	boolean doBridgesWork(String countryCode);
 
+	boolean needsMeek(String countryCode);
+
 	@IoExecutor
-	List<String> getBridges();
+	List<String> getBridges(boolean meek);
 
 }

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

@@ -22,6 +22,8 @@ class CircumventionProviderImpl implements CircumventionProvider {
 			new HashSet<>(asList(BLOCKED));
 	private static final Set<String> BRIDGES_WORK_IN_COUNTRIES =
 			new HashSet<>(asList(BRIDGES));
+	private static final Set<String> BRIDGES_NEED_MEEK =
+			new HashSet<>(asList(NEEDS_MEEK));
 
 	@Nullable
 	private volatile List<String> bridges = null;
@@ -40,9 +42,14 @@ class CircumventionProviderImpl implements CircumventionProvider {
 		return BRIDGES_WORK_IN_COUNTRIES.contains(countryCode);
 	}
 
+	@Override
+	public boolean needsMeek(String countryCode) {
+		return BRIDGES_NEED_MEEK.contains(countryCode);
+	}
+
 	@Override
 	@IoExecutor
-	public List<String> getBridges() {
+	public List<String> getBridges(boolean useMeek) {
 		List<String> bridges = this.bridges;
 		if (bridges != null) return new ArrayList<>(bridges);
 
@@ -53,6 +60,8 @@ class CircumventionProviderImpl implements CircumventionProvider {
 		bridges = new ArrayList<>();
 		while (scanner.hasNextLine()) {
 			String line = scanner.nextLine();
+			boolean isMeekBridge = line.startsWith("Bridge meek");
+			if (useMeek && !isMeekBridge || !useMeek && isMeekBridge) continue;
 			if (!line.startsWith("#")) bridges.add(line);
 		}
 		scanner.close();

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

@@ -470,13 +470,19 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 		if (!enable) callback.transportDisabled();
 	}
 
-	private void enableBridges(boolean enable) throws IOException {
+	private void enableBridges(boolean enable, boolean needsMeek)
+			throws IOException {
 		if (enable) {
 			Collection<String> conf = new ArrayList<>();
 			conf.add("UseBridges 1");
-			conf.add("ClientTransportPlugin obfs4 exec " +
+			if (needsMeek) {
-					obfs4File.getAbsolutePath());
+				conf.add("ClientTransportPlugin meek_lite exec " +
-			conf.addAll(circumventionProvider.getBridges());
+						obfs4File.getAbsolutePath());
+			} else {
+				conf.add("ClientTransportPlugin obfs4 exec " +
+						obfs4File.getAbsolutePath());
+			}
+			conf.addAll(circumventionProvider.getBridges(needsMeek));
 			controlConnection.setConf(conf);
 		} else {
 			controlConnection.setConf("UseBridges", "0");
@@ -716,12 +722,17 @@ abstract class TorPlugin implements DuplexPlugin, EventHandler, EventListener {
 					enableNetwork(false);
 				} else if (network == PREF_TOR_NETWORK_WITH_BRIDGES ||
 						(automatic && bridgesWork)) {
-					LOG.info("Enabling network, using bridges");
+					if (circumventionProvider.needsMeek(country)) {
-					enableBridges(true);
+						LOG.info("Enabling network, using meek bridges");
+						enableBridges(true, true);
+					} else {
+						LOG.info("Enabling network, using obfs4 bridges");
+						enableBridges(true, false);
+					}
 					enableNetwork(true);
 				} else {
 					LOG.info("Enabling network, not using bridges");
-					enableBridges(false);
+					enableBridges(false, false);
 					enableNetwork(true);
 				}
 				if (online && wifi && charging) {

bramble-core/src/main/resources/bridges

@@ -2,3 +2,4 @@ Bridge obfs4 78.46.188.239:37356 5A2D2F4158D0453E00C7C176978D3F41D69C45DB cert=3
 Bridge obfs4 52.15.78.72:9443 02069A3C5362476936B62BA6F5ACC41ABD573A9B cert=ijYG/OKc7kqu2YzKNFfeXN7/BG2BOgfEP2KyYEiGDQthnHbsOiTWHeIG0WJVW+BckzDgKw iat-mode=0
 Bridge obfs4 13.58.29.242:9443 0C58939A77DA6B6B29D4B5236A75865659607AE0 cert=OylWIEHb/ezpq1zWxW0sgKRn+9ARH2eOcQOZ8/Gew+4l+oKOhQ2jUX/Y+FSl61JorXZUWA iat-mode=0
 Bridge obfs4 45.33.37.112:9443 60A609BB4ABE8D46E634AE81ED29ADAB7776B399 cert=t5v19WmNv5Sc2YPNr8RQids365W7MY8zJwQVkOxBjUMFomMWARDzsbYpcWLLcw0J9Gm+BQ iat-mode=0
+Bridge meek_lite 0.0.2.0:2 97700DFE9F483596DDA6264C4D7DF7641E1E39CE url=https://meek.azureedge.net/ front=ajax.aspnetcdn.com

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:0.3.4.8@zip'
+	tor 'org.briarproject:tor:0.3.5.8@zip'
 	tor 'org.briarproject:obfs4proxy:0.0.7@zip'
 
 	annotationProcessor 'com.google.dagger:dagger-compiler:2.19'

bramble-java/src/test/java/org/briarproject/bramble/plugin/tor/BridgeTest.java

@@ -44,7 +44,7 @@ public class BridgeTest extends BrambleTestCase {
 	public static Iterable<String> data() {
 		BrambleJavaIntegrationTestComponent component =
 				DaggerBrambleJavaIntegrationTestComponent.builder().build();
-		return component.getCircumventionProvider().getBridges();
+		return component.getCircumventionProvider().getBridges(false);
 	}
 
 	private final static long TIMEOUT = SECONDS.toMillis(30);
@@ -104,7 +104,12 @@ public class BridgeTest extends BrambleTestCase {
 			}
 
 			@Override
-			public List<String> getBridges() {
+			public boolean needsMeek(String countryCode) {
+				return false;
+			}
+
+			@Override
+			public List<String> getBridges(boolean useMeek) {
 				return singletonList(bridge);
 			}
 		};

bramble-java/witness.gradle

@@ -21,7 +21,7 @@ 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:0.3.4.8:tor-0.3.4.8.zip:bc0158c34002f471a4fe14a6a481816c918eb520a220bb027f64be902beb757f',
+        'org.briarproject:tor:0.3.5.8:tor-0.3.5.8.zip:96e83391f01984f28669235fc02fbb0243140a2b3b2c73aeffd0042c8d3ced18',
         'org.checkerframework:checker-compat-qual:2.5.3:checker-compat-qual-2.5.3.jar:d76b9afea61c7c082908023f0cbc1427fab9abd2df915c8b8a3e7a509bccbc6d',
         'org.codehaus.mojo:animal-sniffer-annotations:1.14:animal-sniffer-annotations-1.14.jar:2068320bd6bad744c3673ab048f67e30bef8f518996fa380033556600669905d',
         'org.hamcrest:hamcrest-core:1.3:hamcrest-core-1.3.jar:66fdef91e9739348df7a096aa384a5685f4e875584cce89386a7a47251c4d8e9',

briar-android/src/main/AndroidManifest.xml

@@ -22,6 +22,7 @@
 	<uses-permission-sdk-23 android:name="android.permission.ACCESS_COARSE_LOCATION" />
 	<uses-permission-sdk-23 android:name="android.permission.REQUEST_IGNORE_BATTERY_OPTIMIZATIONS"/>
 	<uses-permission-sdk-23 android:name="android.permission.USE_BIOMETRIC" />
+	<uses-permission-sdk-23 android:name="android.permission.FOREGROUND_SERVICE" />
 
 	<application
 		android:name="org.briarproject.briar.android.BriarApplicationImpl"

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

@@ -67,6 +67,10 @@ public class ImageActivity extends BriarActivity
 	final static String NAME = "name";
 	final static String DATE = "date";
 
+	@RequiresApi(api = 16)
+	private final static int UI_FLAGS_DEFAULT =
+			SYSTEM_UI_FLAG_LAYOUT_STABLE | SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN;
+
 	@Inject
 	ViewModelProvider.Factory viewModelFactory;
 
@@ -138,9 +142,7 @@ public class ImageActivity extends BriarActivity
 
 		if (SDK_INT >= 16) {
 			viewModel.getOnImageClicked().observe(this, this::onImageClicked);
-			window.getDecorView().setSystemUiVisibility(
+			window.getDecorView().setSystemUiVisibility(UI_FLAGS_DEFAULT);
-					SYSTEM_UI_FLAG_LAYOUT_STABLE |
-							SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN);
 		}
 	}
 
@@ -206,9 +208,16 @@ public class ImageActivity extends BriarActivity
 
 	@Override
 	public void onPullComplete() {
+		showStatusBarBeforeFinishing();
 		supportFinishAfterTransition();
 	}
 
+	@Override
+	public void onBackPressed() {
+		showStatusBarBeforeFinishing();
+		super.onBackPressed();
+	}
+
 	@RequiresApi(api = 16)
 	private void onImageClicked(@Nullable Boolean clicked) {
 		if (clicked != null && clicked) {
@@ -229,9 +238,8 @@ public class ImageActivity extends BriarActivity
 
 	@RequiresApi(api = 16)
 	private void hideSystemUi(View decorView) {
-		decorView.setSystemUiVisibility(SYSTEM_UI_FLAG_FULLSCREEN |
+		decorView.setSystemUiVisibility(
-				SYSTEM_UI_FLAG_LAYOUT_STABLE | SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN
+				SYSTEM_UI_FLAG_FULLSCREEN | UI_FLAGS_DEFAULT);
-		);
 		appBarLayout.animate()
 				.translationYBy(-1 * appBarLayout.getHeight())
 				.alpha(0f)
@@ -241,9 +249,7 @@ public class ImageActivity extends BriarActivity
 
 	@RequiresApi(api = 16)
 	private void showSystemUi(View decorView) {
-		decorView.setSystemUiVisibility(
+		decorView.setSystemUiVisibility(UI_FLAGS_DEFAULT);
-				SYSTEM_UI_FLAG_LAYOUT_STABLE | SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN
-		);
 		appBarLayout.animate()
 				.translationYBy(appBarLayout.getHeight())
 				.alpha(1f)
@@ -251,6 +257,18 @@ public class ImageActivity extends BriarActivity
 				.start();
 	}
 
+	/**
+	 * If we don't show the status bar again before finishing this activity,
+	 * the return transition will "jump" down the size of the status bar
+	 * when the previous activity (with visible status bar) is shown.
+	 */
+	private void showStatusBarBeforeFinishing() {
+		if (SDK_INT >= 16 && appBarLayout.getVisibility() == GONE) {
+			View decorView = getWindow().getDecorView();
+			decorView.setSystemUiVisibility(UI_FLAGS_DEFAULT);
+		}
+	}
+
 	private void showSaveImageDialog() {
 		OnClickListener okListener = (dialog, which) -> {
 			if (SDK_INT >= 19) {

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

@@ -4,9 +4,12 @@ import android.os.Bundle;
 import android.support.annotation.UiThread;
 import android.widget.Toast;
 
-import org.briarproject.bramble.api.contact.ContactExchangeListener;
 import org.briarproject.bramble.api.contact.ContactExchangeTask;
+import org.briarproject.bramble.api.contact.event.ContactExchangeFailedEvent;
+import org.briarproject.bramble.api.contact.event.ContactExchangeSucceededEvent;
 import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.event.Event;
+import org.briarproject.bramble.api.event.EventListener;
 import org.briarproject.bramble.api.identity.Author;
 import org.briarproject.bramble.api.identity.IdentityManager;
 import org.briarproject.bramble.api.identity.LocalAuthor;
@@ -28,7 +31,7 @@ import static org.briarproject.bramble.util.LogUtils.logException;
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
 public class ContactExchangeActivity extends KeyAgreementActivity implements
-		ContactExchangeListener {
+		EventListener {
 
 	private static final Logger LOG =
 			Logger.getLogger(ContactExchangeActivity.class.getName());
@@ -50,6 +53,20 @@ public class ContactExchangeActivity extends KeyAgreementActivity implements
 		getSupportActionBar().setTitle(R.string.add_contact_title);
 	}
 
+	@Override
+	public void onStart() {
+		super.onStart();
+		// Listen to updates from contactExchangeTask
+		eventBus.addListener(this);
+	}
+
+	@Override
+	protected void onStop() {
+		super.onStop();
+		// Stop listen to updates from contactExchangeTask
+		eventBus.addListener(this);
+	}
+
 	private void startContactExchange(KeyAgreementResult result) {
 		runOnDbThread(() -> {
 			LocalAuthor localAuthor;
@@ -63,15 +80,28 @@ public class ContactExchangeActivity extends KeyAgreementActivity implements
 			}
 
 			// Exchange contact details
-			contactExchangeTask.startExchange(ContactExchangeActivity.this,
+			contactExchangeTask.startExchange(localAuthor,
-					localAuthor, result.getMasterKey(),
+					result.getMasterKey(), result.getConnection(),
-					result.getConnection(), result.getTransportId(),
+					result.getTransportId(), result.wasAlice());
-					result.wasAlice());
 		});
 	}
 
 	@Override
-	public void contactExchangeSucceeded(Author remoteAuthor) {
+	public void eventOccurred(Event e) {
+		if (e instanceof ContactExchangeSucceededEvent) {
+			contactExchangeSucceeded(
+					((ContactExchangeSucceededEvent) e).getRemoteAuthor());
+		} else if (e instanceof ContactExchangeFailedEvent) {
+			ContactExchangeFailedEvent fe = (ContactExchangeFailedEvent) e;
+			if (fe.wasDuplicateContact()) {
+				duplicateContact(fe.getDuplicateRemoteAuthor());
+			} else {
+				contactExchangeFailed();
+			}
+		}
+	}
+
+	private void contactExchangeSucceeded(Author remoteAuthor) {
 		runOnUiThreadUnlessDestroyed(() -> {
 			String contactName = remoteAuthor.getName();
 			String format = getString(R.string.contact_added_toast);
@@ -82,8 +112,7 @@ public class ContactExchangeActivity extends KeyAgreementActivity implements
 		});
 	}
 
-	@Override
+	private void duplicateContact(Author remoteAuthor) {
-	public void duplicateContact(Author remoteAuthor) {
 		runOnUiThreadUnlessDestroyed(() -> {
 			String contactName = remoteAuthor.getName();
 			String format = getString(R.string.contact_already_exists);
@@ -94,8 +123,7 @@ public class ContactExchangeActivity extends KeyAgreementActivity implements
 		});
 	}
 
-	@Override
+	private void contactExchangeFailed() {
-	public void contactExchangeFailed() {
 		runOnUiThreadUnlessDestroyed(() -> {
 			showErrorFragment(R.string.connection_error_explanation);
 		});

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

@@ -178,6 +178,14 @@ public class GroupActivity extends
 		} else super.onActivityResult(request, result, data);
 	}
 
+	@Override
+	public void onItemReceived(GroupMessageItem item) {
+		super.onItemReceived(item);
+		if (item instanceof JoinMessageItem) {
+			if (((JoinMessageItem) item).isInitial()) loadSharingContacts();
+		}
+	}
+
 	@Override
 	protected int getMaxTextLength() {
 		return MAX_GROUP_POST_TEXT_LENGTH;

briar-android/src/main/java/org/briarproject/briar/android/privategroup/memberlist/GroupMemberListActivity.java

@@ -7,14 +7,20 @@ import android.view.MenuItem;
 import android.widget.TextView;
 
 import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.event.Event;
+import org.briarproject.bramble.api.event.EventBus;
+import org.briarproject.bramble.api.event.EventListener;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.bramble.api.sync.GroupId;
+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.activity.BriarActivity;
 import org.briarproject.briar.android.controller.handler.UiResultExceptionHandler;
 import org.briarproject.briar.android.view.BriarRecyclerView;
+import org.briarproject.briar.api.privategroup.JoinMessageHeader;
+import org.briarproject.briar.api.privategroup.event.GroupMessageAddedEvent;
 
 import java.util.Collection;
 
@@ -23,10 +29,13 @@ import javax.inject.Inject;
 
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
-public class GroupMemberListActivity extends BriarActivity {
+public class GroupMemberListActivity extends BriarActivity
+		implements EventListener {
 
 	@Inject
 	GroupMemberListController controller;
+	@Inject
+	EventBus eventBus;
 
 	private MemberListAdapter adapter;
 	private BriarRecyclerView list;
@@ -61,28 +70,38 @@ public class GroupMemberListActivity extends BriarActivity {
 	@Override
 	public void onStart() {
 		super.onStart();
-		controller.loadMembers(groupId,
+		loadMembers();
-				new UiResultExceptionHandler<Collection<MemberListItem>, DbException>(
+		eventBus.addListener(this);
-						this) {
-					@Override
-					public void onResultUi(Collection<MemberListItem> members) {
-						adapter.addAll(members);
-					}
-
-					@Override
-					public void onExceptionUi(DbException exception) {
-						handleDbException(exception);
-					}
-				});
 		list.startPeriodicUpdate();
 	}
 
 	@Override
 	public void onStop() {
 		super.onStop();
+		eventBus.removeListener(this);
 		list.stopPeriodicUpdate();
 	}
 
+	@Override
+	public void eventOccurred(Event e) {
+		if (e instanceof GroupMessageAddedEvent) {
+			// we can't use GroupInvitationResponseReceivedEvent, because
+			// a peer only becomes a member after joining the group by message
+			GroupMessageAddedEvent ge = (GroupMessageAddedEvent) e;
+			if (ge.getGroupId().equals(groupId) &&
+					ge.getHeader() instanceof JoinMessageHeader) {
+				loadMembers();
+			}
+		} else if (e instanceof GroupRemovedEvent) {
+			GroupRemovedEvent g = (GroupRemovedEvent) e;
+			if (g.getGroup().getId().equals(groupId)) {
+				runOnUiThreadUnlessDestroyed(
+						this::supportFinishAfterTransition);
+			}
+		}
+		// TODO ContactConnectedEvent and ContactDisconnectedEvent
+	}
+
 	@Override
 	public boolean onOptionsItemSelected(MenuItem item) {
 		switch (item.getItemId()) {
@@ -94,4 +113,20 @@ public class GroupMemberListActivity extends BriarActivity {
 		}
 	}
 
+	private void loadMembers() {
+		controller.loadMembers(groupId,
+				new UiResultExceptionHandler<Collection<MemberListItem>, DbException>(
+						this) {
+					@Override
+					public void onResultUi(Collection<MemberListItem> members) {
+						adapter.addAll(members);
+					}
+
+					@Override
+					public void onExceptionUi(DbException exception) {
+						handleDbException(exception);
+					}
+				});
+	}
+
 }

briar-android/src/main/java/org/briarproject/briar/android/sharing/BlogSharingStatusActivity.java

@@ -3,11 +3,14 @@ package org.briarproject.briar.android.sharing;
 import org.briarproject.bramble.api.contact.Contact;
 import org.briarproject.bramble.api.db.DatabaseExecutor;
 import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.event.Event;
 import org.briarproject.bramble.api.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.api.blog.BlogInvitationResponse;
 import org.briarproject.briar.api.blog.BlogSharingManager;
+import org.briarproject.briar.api.blog.event.BlogInvitationResponseReceivedEvent;
 
 import java.util.Collection;
 
@@ -26,6 +29,19 @@ public class BlogSharingStatusActivity extends SharingStatusActivity {
 		component.inject(this);
 	}
 
+	@Override
+	public void eventOccurred(Event e) {
+		super.eventOccurred(e);
+		if (e instanceof BlogInvitationResponseReceivedEvent) {
+			BlogInvitationResponseReceivedEvent r =
+					(BlogInvitationResponseReceivedEvent) e;
+			BlogInvitationResponse h = r.getMessageHeader();
+			if (h.getShareableId().equals(getGroupId()) && h.wasAccepted()) {
+				loadSharedWith();
+			}
+		}
+	}
+
 	@Override
 	int getInfoText() {
 		return R.string.sharing_status_blog;

briar-android/src/main/java/org/briarproject/briar/android/sharing/ForumSharingStatusActivity.java

@@ -3,11 +3,14 @@ package org.briarproject.briar.android.sharing;
 import org.briarproject.bramble.api.contact.Contact;
 import org.briarproject.bramble.api.db.DatabaseExecutor;
 import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.event.Event;
 import org.briarproject.bramble.api.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.api.forum.ForumInvitationResponse;
 import org.briarproject.briar.api.forum.ForumSharingManager;
+import org.briarproject.briar.api.forum.event.ForumInvitationResponseReceivedEvent;
 
 import java.util.Collection;
 
@@ -26,6 +29,19 @@ public class ForumSharingStatusActivity extends SharingStatusActivity {
 		component.inject(this);
 	}
 
+	@Override
+	public void eventOccurred(Event e) {
+		super.eventOccurred(e);
+		if (e instanceof ForumInvitationResponseReceivedEvent) {
+			ForumInvitationResponseReceivedEvent r =
+					(ForumInvitationResponseReceivedEvent) e;
+			ForumInvitationResponse h = r.getMessageHeader();
+			if (h.getShareableId().equals(getGroupId()) && h.wasAccepted()) {
+				loadSharedWith();
+			}
+		}
+	}
+
 	@Override
 	int getInfoText() {
 		return R.string.sharing_status_forum;

briar-android/src/main/java/org/briarproject/briar/android/sharing/SharingStatusActivity.java

@@ -2,6 +2,7 @@ package org.briarproject.briar.android.sharing;
 
 import android.content.Intent;
 import android.os.Bundle;
+import android.support.annotation.CallSuper;
 import android.support.annotation.StringRes;
 import android.support.v7.widget.LinearLayoutManager;
 import android.view.MenuItem;
@@ -10,14 +11,19 @@ import android.widget.TextView;
 import org.briarproject.bramble.api.contact.Contact;
 import org.briarproject.bramble.api.db.DatabaseExecutor;
 import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.event.Event;
+import org.briarproject.bramble.api.event.EventBus;
+import org.briarproject.bramble.api.event.EventListener;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.bramble.api.plugin.ConnectionRegistry;
 import org.briarproject.bramble.api.sync.GroupId;
+import org.briarproject.bramble.api.sync.event.GroupRemovedEvent;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.activity.BriarActivity;
 import org.briarproject.briar.android.contact.ContactItem;
 import org.briarproject.briar.android.view.BriarRecyclerView;
+import org.briarproject.briar.api.sharing.event.ContactLeftShareableEvent;
 
 import java.util.ArrayList;
 import java.util.Collection;
@@ -32,10 +38,13 @@ import static org.briarproject.bramble.util.LogUtils.logException;
 
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
-abstract class SharingStatusActivity extends BriarActivity {
+abstract class SharingStatusActivity extends BriarActivity
+		implements EventListener {
 
 	@Inject
 	ConnectionRegistry connectionRegistry;
+	@Inject
+	EventBus eventBus;
 
 	private static final Logger LOG =
 			Logger.getLogger(SharingStatusActivity.class.getName());
@@ -68,6 +77,7 @@ abstract class SharingStatusActivity extends BriarActivity {
 	@Override
 	public void onStart() {
 		super.onStart();
+		eventBus.addListener(this);
 		loadSharedWith();
 	}
 
@@ -75,9 +85,28 @@ abstract class SharingStatusActivity extends BriarActivity {
 	public void onStop() {
 		super.onStop();
 		adapter.clear();
+		eventBus.removeListener(this);
 		list.showProgressBar();
 	}
 
+	@Override
+	@CallSuper
+	public void eventOccurred(Event e) {
+		if (e instanceof ContactLeftShareableEvent) {
+			ContactLeftShareableEvent c = (ContactLeftShareableEvent) e;
+			if (c.getGroupId().equals(getGroupId())) {
+				loadSharedWith();
+			}
+		} else if (e instanceof GroupRemovedEvent) {
+			GroupRemovedEvent g = (GroupRemovedEvent) e;
+			if (g.getGroup().getId().equals(getGroupId())) {
+				runOnUiThreadUnlessDestroyed(
+						this::supportFinishAfterTransition);
+			}
+		}
+		// TODO ContactConnectedEvent and ContactDisconnectedEvent
+	}
+
 	@Override
 	public boolean onOptionsItemSelected(MenuItem item) {
 		// Handle presses on the action bar items
@@ -100,7 +129,7 @@ abstract class SharingStatusActivity extends BriarActivity {
 		return groupId;
 	}
 
-	private void loadSharedWith() {
+	protected void loadSharedWith() {
 		runOnDbThread(() -> {
 			try {
 				List<ContactItem> contactItems = new ArrayList<>();
@@ -118,6 +147,7 @@ abstract class SharingStatusActivity extends BriarActivity {
 
 	private void displaySharedWith(List<ContactItem> contacts) {
 		runOnUiThreadUnlessDestroyed(() -> {
+			adapter.clear();
 			if (contacts.isEmpty()) list.showData();
 			else adapter.addAll(contacts);
 		});

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

@@ -82,11 +82,11 @@
 		android:layout_marginStart="@dimen/listitem_horizontal_margin"
 		android:layout_marginTop="@dimen/margin_medium"
 		android:textColor="?android:attr/textColorTertiary"
-		app:layout_constraintEnd_toEndOf="parent"
+		app:layout_constraintEnd_toStartOf="@+id/removeButton"
 		app:layout_constraintLeft_toRightOf="@+id/avatarView"
 		app:layout_constraintStart_toEndOf="@+id/avatarView"
 		app:layout_constraintTop_toBottomOf="@+id/messageCountView"
-		tools:text="@string/groups_group_is_empty"/>
+		tools:text="This group is empty, but has a long status text"/>
 
 	<Button
 		android:id="@+id/removeButton"
@@ -94,9 +94,11 @@
 		android:layout_width="wrap_content"
 		android:layout_height="wrap_content"
 		android:text="@string/groups_remove"
+		android:visibility="gone"
 		app:layout_constraintBottom_toBottomOf="@+id/divider"
 		app:layout_constraintRight_toRightOf="parent"
-		tools:visibility="gone"/>
+		app:layout_constraintTop_toTopOf="@+id/statusView"
+		tools:visibility="visible"/>
 
 	<View
 		android:id="@+id/divider"

briar-android/src/main/res/menu/group_actions.xml

@@ -13,7 +13,7 @@
 		android:id="@+id/action_group_member_list"
 		android:icon="@drawable/ic_group_white"
 		android:title="@string/groups_member_list"
-		app:showAsAction="ifRoom"/>
+		app:showAsAction="never"/>
 
 	<item
 		android:id="@+id/action_group_reveal"

briar-core/src/main/java/org/briarproject/briar/messaging/MessagingManagerImpl.java

@@ -1,6 +1,7 @@
 package org.briarproject.briar.messaging;
 
 import org.briarproject.bramble.api.FormatException;
+import org.briarproject.bramble.api.UniqueId;
 import org.briarproject.bramble.api.client.ClientHelper;
 import org.briarproject.bramble.api.client.ContactGroupFactory;
 import org.briarproject.bramble.api.contact.Contact;
@@ -32,11 +33,12 @@ import org.briarproject.briar.api.messaging.PrivateMessageHeader;
 import org.briarproject.briar.api.messaging.event.PrivateMessageReceivedEvent;
 import org.briarproject.briar.client.ConversationClientImpl;
 
-import java.io.ByteArrayInputStream;
+import java.io.BufferedInputStream;
 import java.io.IOException;
 import java.io.InputStream;
 import java.util.ArrayList;
 import java.util.Collection;
+import java.util.List;
 import java.util.Map;
 import java.util.Random;
 
@@ -44,7 +46,7 @@ import javax.annotation.concurrent.Immutable;
 import javax.inject.Inject;
 
 import static java.util.Collections.emptyList;
-import static org.briarproject.bramble.util.StringUtils.fromHexString;
+import static java.util.logging.Logger.getLogger;
 import static org.briarproject.briar.client.MessageTrackerConstants.MSG_KEY_READ;
 
 @Immutable
@@ -219,8 +221,26 @@ class MessagingManagerImpl extends ConversationClientImpl
 				long timestamp = meta.getLong("timestamp");
 				boolean local = meta.getBoolean("local");
 				boolean read = meta.getBoolean("read");
+				// TODO replace fake attachments by real ones
+				boolean hasText;
+				List<AttachmentHeader> attachments;
+				Random random = new Random(id.hashCode());
+				if (random.nextBoolean()) {
+					hasText = random.nextBoolean();
+					attachments = new ArrayList<>();
+					int numAttachments = random.nextInt(10) + 1;
+					for (int i = 0; i < numAttachments; i++) {
+						byte[] b = new byte[UniqueId.LENGTH];
+						random.nextBytes(b);
+						attachments.add(new AttachmentHeader(new MessageId(b),
+								"image/jpeg"));
+					}
+				} else {
+					hasText = true;
+					attachments = emptyList();
+				}
 				headers.add(new PrivateMessageHeader(id, g, timestamp, local,
-						read, s.isSent(), s.isSeen(), true, emptyList()));
+						read, s.isSent(), s.isSeen(), hasText, attachments));
 			} catch (FormatException e) {
 				throw new DbException(e);
 			}
@@ -241,11 +261,30 @@ class MessagingManagerImpl extends ConversationClientImpl
 	@Override
 	public Attachment getAttachment(MessageId m) {
 		// TODO add real implementation
-		byte[] bytes = fromHexString("89504E470D0A1A0A0000000D49484452" +
+		String[] files = new String[] {
-				"000000010000000108060000001F15C4" +
+//				"error_animated.gif",
-				"890000000A49444154789C6300010000" +
+//				"error_high.jpg",
-				"0500010D0A2DB40000000049454E44AE426082");
+//				"error_wide.jpg",
-		return new Attachment(new ByteArrayInputStream(bytes));
+//				"error_huge.gif",
+//				"error_large.gif",
+//				"error_malformed.jpg",
+//				"wide.jpg",
+//				"high.jpg",
+//				"small.png",
+				"kitten1.jpg",
+				"kitten2.jpg",
+				"kitten3.gif",
+				"kitten4.jpg",
+				"kitten5.jpg",
+				"kitten6.png",
+		};
+		int index = Math.abs(m.hashCode() % files.length);
+		String file = files[index];
+		getLogger(MessagingManagerImpl.class.getName())
+				.warning("Loading file: " + file);
+
+		InputStream is = getClass().getClassLoader().getResourceAsStream(file);
+		return new Attachment(new BufferedInputStream(is));
 	}
 
 	@Override

briar-headless/README.md

@@ -11,6 +11,10 @@ The REST API peer comes as a `jar` file
 and needs a Java Runtime Environment (JRE) that supports at least Java 8.
 It currently works only on GNU/Linux operating systems.
 
+To build the `jar` file, you can do this:
+
+    $ ./gradlew --configure-on-demand briar-headless:jar
+
 You can start the peer (and its API server) like this:
 
     $ java -jar briar-headless/build/libs/briar-headless.jar