Second part of BQP UI improvements: zxing viewfinder.

Introduce a MessageContext class to be used by all validators

This change will allow to pass message dependencies from the client validators to the `ValidationManager`.

Please see my thoughts in #382 for more details.

See merge request !197

briar-android-tests/build.gradle

@@ -2,10 +2,6 @@ apply plugin: 'com.android.library'
 apply plugin: 'witness'
 apply plugin: 'com.neenbedankt.android-apt'
 
-repositories {
-    maven { url 'http://repo1.maven.org/maven2' }
-}
-
 android {
     compileSdkVersion 23
     buildToolsVersion "23.0.3"

briar-android-tests/src/test/java/org/briarproject/ForumSharingIntegrationTest.java

@@ -49,6 +49,7 @@ import java.io.ByteArrayOutputStream;
 import java.io.File;
 import java.io.IOException;
 import java.util.ArrayList;
+import java.util.Collection;
 import java.util.List;
 import java.util.concurrent.TimeoutException;
 import java.util.logging.Logger;
@@ -65,15 +66,15 @@ import static org.junit.Assert.assertTrue;
 
 public class ForumSharingIntegrationTest extends BriarTestCase {
 
-	LifecycleManager lifecycleManager0, lifecycleManager1;
-	SyncSessionFactory sync0, sync1;
-	ForumManager forumManager0, forumManager1;
-	ContactManager contactManager0, contactManager1;
-	ContactId contactId0, contactId1;
-	IdentityManager identityManager0, identityManager1;
-	LocalAuthor author0, author1;
+	LifecycleManager lifecycleManager0, lifecycleManager1, lifecycleManager2;
+	SyncSessionFactory sync0, sync1, sync2;
+	ForumManager forumManager0, forumManager1, forumManager2;
+	ContactManager contactManager0, contactManager1, contactManager2;
+	ContactId contactId0, contactId2, contactId1, contactId21;
+	IdentityManager identityManager0, identityManager1, identityManager2;
+	LocalAuthor author0, author1, author2;
 	Forum forum0;
-	SharerListener listener0;
+	SharerListener listener0, listener2;
 	InviteeListener listener1;
 
 	@Inject
@@ -84,6 +85,7 @@ public class ForumSharingIntegrationTest extends BriarTestCase {
 	// objects accessed from background threads need to be volatile
 	private volatile ForumSharingManager forumSharingManager0;
 	private volatile ForumSharingManager forumSharingManager1;
+	private volatile ForumSharingManager forumSharingManager2;
 	private volatile Waiter eventWaiter;
 	private volatile Waiter msgWaiter;
 
@@ -92,11 +94,12 @@ public class ForumSharingIntegrationTest extends BriarTestCase {
 	private final int TIMEOUT = 15000;
 	private final String SHARER = "Sharer";
 	private final String INVITEE = "Invitee";
+	private final String SHARER2 = "Sharer2";
 
 	private static final Logger LOG =
 			Logger.getLogger(ForumSharingIntegrationTest.class.getName());
 
-	private ForumSharingIntegrationTestComponent t0, t1;
+	private ForumSharingIntegrationTestComponent t0, t1, t2;
 
 	@Rule
 	public ExpectedException thrown=ExpectedException.none();
@@ -117,17 +120,26 @@ public class ForumSharingIntegrationTest extends BriarTestCase {
 		t1 = DaggerForumSharingIntegrationTestComponent.builder()
 				.testDatabaseModule(new TestDatabaseModule(t1Dir)).build();
 		injectEagerSingletons(t1);
+		File t2Dir = new File(testDir, SHARER2);
+		t2 = DaggerForumSharingIntegrationTestComponent.builder()
+				.testDatabaseModule(new TestDatabaseModule(t2Dir)).build();
+		injectEagerSingletons(t2);
 
 		identityManager0 = t0.getIdentityManager();
 		identityManager1 = t1.getIdentityManager();
+		identityManager2 = t2.getIdentityManager();
 		contactManager0 = t0.getContactManager();
 		contactManager1 = t1.getContactManager();
+		contactManager2 = t2.getContactManager();
 		forumManager0 = t0.getForumManager();
 		forumManager1 = t1.getForumManager();
+		forumManager2 = t2.getForumManager();
 		forumSharingManager0 = t0.getForumSharingManager();
 		forumSharingManager1 = t1.getForumSharingManager();
+		forumSharingManager2 = t2.getForumSharingManager();
 		sync0 = t0.getSyncSessionFactory();
 		sync1 = t1.getSyncSessionFactory();
+		sync2 = t2.getSyncSessionFactory();
 
 		// initialize waiters fresh for each test
 		eventWaiter = new Waiter();
@@ -261,8 +273,9 @@ public class ForumSharingIntegrationTest extends BriarTestCase {
 			assertTrue(forumManager1.getForums().contains(forum0));
 
 			// sharer shares forum with invitee
+			Contact c1 = contactManager0.getContact(contactId1);
 			assertTrue(forumSharingManager0.getSharedWith(forum0.getId())
-					.contains(contactId1));
+					.contains(c1));
 			// invitee gets forum shared by sharer
 			Contact contact0 = contactManager1.getContact(contactId1);
 			assertTrue(forumSharingManager1.getSharedBy(forum0.getId())
@@ -280,12 +293,11 @@ public class ForumSharingIntegrationTest extends BriarTestCase {
 
 			// sharer no longer shares forum with invitee
 			assertFalse(forumSharingManager0.getSharedWith(forum0.getId())
-					.contains(contactId1));
+					.contains(c1));
 			// invitee no longer gets forum shared by sharer
 			assertFalse(forumSharingManager1.getSharedBy(forum0.getId())
 					.contains(contact0));
 			// forum can be shared again
-			Contact c1 = contactManager0.getContact(contactId1);
 			assertTrue(forumSharingManager0.canBeShared(forum0.getId(), c1));
 			Contact c0 = contactManager1.getContact(contactId0);
 			assertTrue(forumSharingManager1.canBeShared(forum0.getId(), c0));
@@ -321,8 +333,9 @@ public class ForumSharingIntegrationTest extends BriarTestCase {
 			assertTrue(forumManager1.getForums().contains(forum0));
 
 			// sharer shares forum with invitee
+			Contact c1 = contactManager0.getContact(contactId1);
 			assertTrue(forumSharingManager0.getSharedWith(forum0.getId())
-					.contains(contactId1));
+					.contains(c1));
 			// invitee gets forum shared by sharer
 			Contact contact0 = contactManager1.getContact(contactId1);
 			assertTrue(forumSharingManager1.getSharedBy(forum0.getId())
@@ -339,13 +352,13 @@ public class ForumSharingIntegrationTest extends BriarTestCase {
 			assertEquals(1, forumManager1.getForums().size());
 
 			// invitee no longer shares forum with sharer
+			Contact c0 = contactManager1.getContact(contactId0);
 			assertFalse(forumSharingManager1.getSharedWith(forum0.getId())
-					.contains(contactId0));
+					.contains(c0));
 			// sharer no longer gets forum shared by invitee
 			assertFalse(forumSharingManager1.getSharedBy(forum0.getId())
 					.contains(contact0));
 			// forum can be shared again
-			Contact c0 = contactManager1.getContact(contactId0);
 			assertTrue(forumSharingManager1.canBeShared(forum0.getId(), c0));
 		} finally {
 			stopLifecycles();
@@ -474,7 +487,8 @@ public class ForumSharingIntegrationTest extends BriarTestCase {
 			assertEquals(1, forumManager1.getForums().size());
 
 			// invitee now shares same forum back
-			forumSharingManager1.sendForumInvitation(forum0.getId(), contactId0,
+			forumSharingManager1.sendForumInvitation(forum0.getId(),
+					contactId0,
 					"I am re-sharing this forum with you.");
 
 			// sync re-share invitation
@@ -526,7 +540,9 @@ public class ForumSharingIntegrationTest extends BriarTestCase {
 
 			// contacts now remove each other
 			contactManager0.removeContact(contactId1);
+			contactManager2.removeContact(contactId21);
 			contactManager1.removeContact(contactId0);
+			contactManager1.removeContact(contactId2);
 
 			// make sure sharer does share the forum with nobody now
 			assertEquals(0,
@@ -572,6 +588,75 @@ public class ForumSharingIntegrationTest extends BriarTestCase {
 		}
 	}
 
+	@Test
+	public void testTwoContactsShareSameForum() throws Exception {
+		startLifecycles();
+		try {
+			// initialize
+			addDefaultIdentities();
+			addDefaultContacts();
+			addForumForSharer();
+
+			// second sharer adds the same forum
+			DatabaseComponent db2 = t2.getDatabaseComponent();
+			Transaction txn = db2.startTransaction(false);
+			db2.addGroup(txn, forum0.getGroup());
+			txn.setComplete();
+			db2.endTransaction(txn);
+
+			// add listeners
+			listener0 = new SharerListener();
+			t0.getEventBus().addListener(listener0);
+			listener1 = new InviteeListener(true, false);
+			t1.getEventBus().addListener(listener1);
+			listener2 = new SharerListener();
+			t2.getEventBus().addListener(listener2);
+
+			// send invitation
+			forumSharingManager0
+					.sendForumInvitation(forum0.getId(), contactId1, "Hi!");
+			// sync first request message
+			syncToInvitee();
+
+			// second sharer sends invitation for same forum
+			forumSharingManager2
+					.sendForumInvitation(forum0.getId(), contactId1, null);
+			// sync second request message
+			deliverMessage(sync2, contactId2, sync1, contactId1,
+					"Sharer2 to Invitee");
+
+			// make sure we have only one forum available
+			Collection<Forum> forums =
+					forumSharingManager1.getAvailableForums();
+			assertEquals(1, forums.size());
+
+			// make sure both sharers actually share the forum
+			Collection<Contact> contacts =
+					forumSharingManager1.getSharedBy(forum0.getId());
+			assertEquals(2, contacts.size());
+
+			// answer second request
+			Contact c2 = contactManager1.getContact(contactId2);
+			forumSharingManager1.respondToInvitation(forum0, c2, true);
+			// sync response
+			deliverMessage(sync1, contactId21, sync2, contactId2,
+					"Invitee to Sharer2");
+			eventWaiter.await(TIMEOUT, 1);
+			assertTrue(listener2.responseReceived);
+
+			// answer first request
+			Contact c0 =
+					contactManager1.getContact(contactId0);
+			forumSharingManager1.respondToInvitation(forum0, c0, true);
+			// sync response
+			syncToSharer();
+			eventWaiter.await(TIMEOUT, 1);
+			assertTrue(listener0.responseReceived);
+		} finally {
+			stopLifecycles();
+		}
+	}
+
 
 	@After
 	public void tearDown() throws InterruptedException {
@@ -609,7 +694,8 @@ public class ForumSharingIntegrationTest extends BriarTestCase {
 				requestReceived = true;
 				Forum f = event.getForum();
 				try {
-					forumSharingManager0.respondToInvitation(f, true);
+					Contact c = contactManager0.getContact(contactId1);
+					forumSharingManager0.respondToInvitation(f, c, true);
 				} catch (DbException ex) {
 					eventWaiter.rethrow(ex);
 				} finally {
@@ -624,10 +710,15 @@ public class ForumSharingIntegrationTest extends BriarTestCase {
 		public volatile boolean requestReceived = false;
 		public volatile boolean responseReceived = false;
 
-		private final boolean accept;
+		private final boolean accept, answer;
+
+		InviteeListener(boolean accept, boolean answer) {
+			this.accept = accept;
+			this.answer = answer;
+		}
 
 		InviteeListener(boolean accept) {
-			this.accept = accept;
+			this(accept, true);
 		}
 
 		public void eventOccurred(Event e) {
@@ -644,13 +735,13 @@ public class ForumSharingIntegrationTest extends BriarTestCase {
 			} else if (e instanceof ForumInvitationReceivedEvent) {
 				ForumInvitationReceivedEvent event =
 						(ForumInvitationReceivedEvent) e;
-				eventWaiter.assertEquals(contactId0, event.getContactId());
 				requestReceived = true;
+				if (!answer) return;
 				Forum f = event.getForum();
-				// work-around because the forum does not contain the group
-				f = forumManager1.createForum(f.getName(), f.getSalt());
 				try {
-					forumSharingManager1.respondToInvitation(f, accept);
+					Contact c =
+							contactManager1.getContact(event.getContactId());
+					forumSharingManager1.respondToInvitation(f, c, accept);
 				} catch (DbException ex) {
 					eventWaiter.rethrow(ex);
 				} finally {
@@ -672,18 +763,23 @@ public class ForumSharingIntegrationTest extends BriarTestCase {
 		// Start the lifecycle manager and wait for it to finish
 		lifecycleManager0 = t0.getLifecycleManager();
 		lifecycleManager1 = t1.getLifecycleManager();
+		lifecycleManager2 = t2.getLifecycleManager();
 		lifecycleManager0.startServices();
 		lifecycleManager1.startServices();
+		lifecycleManager2.startServices();
 		lifecycleManager0.waitForStartup();
 		lifecycleManager1.waitForStartup();
+		lifecycleManager2.waitForStartup();
 	}
 
 	private void stopLifecycles() throws InterruptedException {
 		// Clean up
 		lifecycleManager0.stopServices();
 		lifecycleManager1.stopServices();
+		lifecycleManager2.stopServices();
 		lifecycleManager0.waitForShutdown();
 		lifecycleManager1.waitForShutdown();
+		lifecycleManager2.waitForShutdown();
 	}
 
 	private void defaultInit(boolean accept) throws DbException {
@@ -702,6 +798,10 @@ public class ForumSharingIntegrationTest extends BriarTestCase {
 				TestUtils.getRandomBytes(MAX_PUBLIC_KEY_LENGTH),
 				TestUtils.getRandomBytes(123));
 		identityManager1.addLocalAuthor(author1);
+		author2 = authorFactory.createLocalAuthor(SHARER2,
+				TestUtils.getRandomBytes(MAX_PUBLIC_KEY_LENGTH),
+				TestUtils.getRandomBytes(123));
+		identityManager2.addLocalAuthor(author2);
 	}
 
 	private void addDefaultContacts() throws DbException {
@@ -710,17 +810,25 @@ public class ForumSharingIntegrationTest extends BriarTestCase {
 				author0.getId(), master, clock.currentTimeMillis(), true,
 				true
 		);
-		// invitee adds sharer back
+		// second sharer does the same
+		contactId21 = contactManager2.addContact(author1,
+				author2.getId(), master, clock.currentTimeMillis(), true,
+				true
+		);
+		// invitee adds sharers back
 		contactId0 = contactManager1.addContact(author0,
 				author1.getId(), master, clock.currentTimeMillis(), true,
 				true
 		);
+		contactId2 = contactManager1.addContact(author2,
+				author1.getId(), master, clock.currentTimeMillis(), true,
+				true
+		);
 	}
 
 	private void addForumForSharer() throws DbException {
 		// sharer creates forum
-		forum0 = forumManager0.createForum("Test Forum");
-		forumManager0.addForum(forum0);
+		forum0 = forumManager0.addForum("Test Forum");
 	}
 
 	private void listenToEvents(boolean accept) {
@@ -728,6 +836,8 @@ public class ForumSharingIntegrationTest extends BriarTestCase {
 		t0.getEventBus().addListener(listener0);
 		listener1 = new InviteeListener(accept);
 		t1.getEventBus().addListener(listener1);
+		listener2 = new SharerListener();
+		t2.getEventBus().addListener(listener2);
 	}
 
 	private void syncToInvitee() throws IOException, TimeoutException {

briar-android-tests/src/test/java/org/briarproject/IntroductionIntegrationTest.java

@@ -832,6 +832,106 @@ public class IntroductionIntegrationTest extends BriarTestCase {
 		}
 	}
 
+	@Test
+	public void testIntroduceesRemovedCleanup() throws Exception {
+		startLifecycles();
+		try {
+			// Add Identities
+			addDefaultIdentities();
+
+			// Add Transport Properties
+			addTransportProperties();
+
+			// Add introducees as contacts
+			contactId1 = contactManager0.addContact(author1,
+					author0.getId(), master, clock.currentTimeMillis(), true,
+					true
+			);
+			contactId2 = contactManager0.addContact(author2,
+					author0.getId(), master, clock.currentTimeMillis(), true,
+					true
+			);
+			// Add introducer back
+			contactId0 = contactManager1.addContact(author0,
+					author1.getId(), master, clock.currentTimeMillis(), true,
+					true
+			);
+			ContactId contactId02 = contactManager2.addContact(author0,
+					author2.getId(), master, clock.currentTimeMillis(), true,
+					true
+			);
+			assertTrue(contactId0.equals(contactId02));
+
+			// listen to events
+			IntroducerListener listener0 = new IntroducerListener();
+			t0.getEventBus().addListener(listener0);
+			IntroduceeListener listener1 = new IntroduceeListener(1, true);
+			t1.getEventBus().addListener(listener1);
+			IntroduceeListener listener2 = new IntroduceeListener(2, true);
+			t2.getEventBus().addListener(listener2);
+
+			// make introduction
+			long time = clock.currentTimeMillis();
+			Contact introducee1 = contactManager0.getContact(contactId1);
+			Contact introducee2 = contactManager0.getContact(contactId2);
+			introductionManager0
+					.makeIntroduction(introducee1, introducee2, "Hi!", time);
+
+			// sync first request message
+			deliverMessage(sync0, contactId0, sync1, contactId1, "0 to 1");
+			eventWaiter.await(TIMEOUT, 1);
+			assertTrue(listener1.requestReceived);
+
+			// get database and local group for introducee
+			DatabaseComponent db0 = t0.getDatabaseComponent();
+			IntroductionGroupFactory groupFactory0 =
+					t0.getIntroductionGroupFactory();
+			Group group1 = groupFactory0.createLocalGroup();
+
+			// get local session state messages
+			Map<MessageId, Metadata> map;
+			Transaction txn = db0.startTransaction(false);
+			try {
+				map = db0.getMessageMetadata(txn, group1.getId());
+				txn.setComplete();
+			} finally {
+				db0.endTransaction(txn);
+			}
+			// check that we have one session state
+			assertEquals(1, map.size());
+
+			// introducer removes introducee1
+			contactManager0.removeContact(contactId1);
+
+			// get local session state messages again
+			txn = db0.startTransaction(false);
+			try {
+				map = db0.getMessageMetadata(txn, group1.getId());
+				txn.setComplete();
+			} finally {
+				db0.endTransaction(txn);
+			}
+			// make sure local state is still there
+			assertEquals(1, map.size());
+
+			// introducer removes other introducee
+			contactManager0.removeContact(contactId2);
+
+			// get local session state messages again
+			txn = db0.startTransaction(false);
+			try {
+				map = db0.getMessageMetadata(txn, group1.getId());
+				txn.setComplete();
+			} finally {
+				db0.endTransaction(txn);
+			}
+			// make sure local state is gone now
+			assertEquals(0, map.size());
+		} finally {
+			stopLifecycles();
+		}
+	}
+
 	// TODO add a test for faking responses when #256 is implemented
 
 	@After

briar-android/AndroidManifest.xml

@@ -149,6 +149,16 @@
 				/>
 		</activity>
 
+		<activity
+			android:name=".android.forum.ForumSharingStatusActivity"
+			android:label="@string/forum_sharing_status"
+			android:parentActivityName=".android.forum.ForumActivity">
+			<meta-data
+				android:name="android.support.PARENT_ACTIVITY"
+				android:value=".android.forum.ForumActivity"
+				/>
+		</activity>
+
 		<activity
 			android:name=".android.forum.WriteForumPostActivity"
 			android:label="@string/app_name"

briar-android/build.gradle

@@ -6,11 +6,6 @@ apply plugin: 'witness'
 apply plugin: 'com.neenbedankt.android-apt'
 apply plugin: 'de.undercouch.download'
 
-repositories {
-	jcenter()
-	maven { url "https://oss.sonatype.org/content/repositories/snapshots" }
-}
-
 dependencies {
 	def supportVersion = '23.2.1'
 	compile project(':briar-api')

briar-android/res/drawable/bubble.xml

@@ -0,0 +1,21 @@
+<?xml version="1.0" encoding="utf-8"?>
+<shape
+	xmlns:android="http://schemas.android.com/apk/res/android"
+	android:shape="rectangle">
+
+	<corners
+		android:radius="@dimen/unread_bubble_size"/>
+
+	<padding
+		android:left="@dimen/unread_bubble_padding_horizontal"
+		android:right="@dimen/unread_bubble_padding_horizontal"/>
+
+	<solid
+		android:color="@color/briar_primary"/>
+
+	<stroke
+		android:color="@color/briar_text_primary_inverse"
+	    android:width="@dimen/avatar_border_width"/>
+
+</shape>
+

briar-android/res/layout/activity_create_identity.xml

@@ -0,0 +1,52 @@
+<?xml version="1.0" encoding="utf-8"?>
+<LinearLayout
+	xmlns:android="http://schemas.android.com/apk/res/android"
+	xmlns:app="http://schemas.android.com/apk/res-auto"
+	android:layout_width="match_parent"
+	android:layout_height="match_parent"
+	android:orientation="vertical"
+	android:padding="@dimen/margin_activity_horizontal">
+
+	<TextView
+		android:layout_width="wrap_content"
+		android:layout_height="wrap_content"
+		android:layout_gravity="center_horizontal"
+		android:text="@string/choose_nickname"
+		android:textSize="@dimen/text_size_large"/>
+
+	<android.support.design.widget.TextInputLayout
+		android:id="@+id/nicknameInputLayout"
+		android:layout_width="match_parent"
+		android:layout_height="wrap_content"
+		app:errorEnabled="true">
+
+		<EditText
+			android:id="@+id/nicknameEntry"
+			android:layout_width="match_parent"
+			android:layout_height="wrap_content"
+			android:layout_gravity="center_horizontal"
+			android:ems="10"
+			android:inputType="textPersonName"
+			android:maxLines="1"/>
+
+	</android.support.design.widget.TextInputLayout>
+
+	<Button
+		android:id="@+id/createIdentityButton"
+		style="@style/BriarButton"
+		android:layout_width="wrap_content"
+		android:layout_height="wrap_content"
+		android:layout_gravity="center_horizontal"
+		android:enabled="false"
+		android:text="@string/create_identity_button"/>
+
+	<ProgressBar
+		android:id="@+id/progressBar"
+		style="?android:attr/progressBarStyleLarge"
+		android:layout_width="wrap_content"
+		android:layout_height="wrap_content"
+		android:layout_gravity="center_horizontal"
+		android:indeterminate="true"
+		android:visibility="gone"/>
+
+</LinearLayout>

briar-android/res/layout/activity_expired.xml

@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="utf-8"?>
+<TextView
+	xmlns:android="http://schemas.android.com/apk/res/android"
+	android:layout_width="match_parent"
+	android:layout_height="match_parent"
+	android:layout_gravity="center"
+	android:gravity="center"
+	android:text="@string/expiry_warning"
+	android:textSize="@dimen/text_size_large"/>

briar-android/res/layout/activity_forum_sharing_status.xml

@@ -0,0 +1,48 @@
+<?xml version="1.0" encoding="utf-8"?>
+<ScrollView
+	xmlns:android="http://schemas.android.com/apk/res/android"
+	android:layout_width="match_parent"
+	android:layout_height="match_parent">
+
+	<LinearLayout
+		android:layout_width="match_parent"
+		android:layout_height="wrap_content"
+		android:orientation="vertical">
+
+		<TextView
+			android:layout_width="match_parent"
+			android:layout_height="wrap_content"
+			android:background="@color/default_separator_inverted"
+			android:padding="@dimen/margin_medium"
+			android:text="@string/forum_shared_by"
+			android:textSize="@dimen/text_size_large"/>
+
+		<View style="@style/Divider.ForumList"/>
+
+		<org.briarproject.android.util.BriarRecyclerView
+			android:id="@+id/sharedByView"
+			android:layout_width="match_parent"
+			android:layout_height="wrap_content"
+			android:paddingBottom="@dimen/margin_medium"
+			android:paddingTop="@dimen/margin_medium"/>
+
+		<TextView
+			android:layout_width="match_parent"
+			android:layout_height="wrap_content"
+			android:background="@color/default_separator_inverted"
+			android:padding="@dimen/margin_medium"
+			android:text="@string/forum_shared_with"
+			android:textSize="@dimen/text_size_large"/>
+
+		<View style="@style/Divider.ForumList"/>
+
+		<org.briarproject.android.util.BriarRecyclerView
+			android:id="@+id/sharedWithView"
+			android:layout_width="match_parent"
+			android:layout_height="wrap_content"
+			android:paddingBottom="@dimen/margin_medium"
+			android:paddingTop="@dimen/margin_medium"/>
+
+	</LinearLayout>
+
+</ScrollView>

briar-android/res/layout/author_view.xml

@@ -1,19 +1,19 @@
 <?xml version="1.0" encoding="utf-8"?>
 <RelativeLayout
 	xmlns:android="http://schemas.android.com/apk/res/android"
-	xmlns:app="http://schemas.android.com/apk/res-auto"
+	xmlns:tools="http://schemas.android.com/tools"
 	android:layout_width="match_parent"
 	android:layout_height="match_parent">
 
 	<de.hdodenhof.circleimageview.CircleImageView
 		android:id="@+id/avatarView"
+		style="@style/BriarAvatar"
 		android:layout_width="@dimen/listitem_picture_size"
 		android:layout_height="@dimen/listitem_picture_size"
 		android:layout_centerVertical="true"
 		android:layout_marginLeft="@dimen/listitem_horizontal_margin"
 		android:layout_marginStart="@dimen/listitem_horizontal_margin"
-		app:civ_border_width="@dimen/avatar_border_width"
-		app:civ_border_color="@color/briar_primary"/>
+		tools:src="@drawable/ic_launcher"/>
 
 	<ImageView
 		android:id="@+id/statusView"

briar-android/res/layout/contact_avatar_status.xml

@@ -9,11 +9,10 @@
 
 	<de.hdodenhof.circleimageview.CircleImageView
 		android:id="@+id/contactAvatar"
+		style="@style/BriarAvatar"
 		android:layout_width="30dp"
 		android:layout_height="30dp"
-		android:transitionName="avatar"
 		app:civ_border_color="@color/action_bar_text"
-		app:civ_border_width="@dimen/avatar_border_width"
 		tools:src="@drawable/ic_launcher"/>
 
 	<ImageView
@@ -22,7 +21,7 @@
 		android:layout_height="15dp"
 		android:layout_gravity="bottom|right"
 		android:scaleType="fitCenter"
-		tools:src="@drawable/contact_online"
-		tools:ignore="ContentDescription"/>
+		tools:ignore="ContentDescription"
+		tools:src="@drawable/contact_online"/>
 
 </FrameLayout>

briar-android/res/layout/dropdown_author.xml

@@ -1,7 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
 <LinearLayout
 	xmlns:android="http://schemas.android.com/apk/res/android"
-	xmlns:app="http://schemas.android.com/apk/res-auto"
 	xmlns:tools="http://schemas.android.com/tools"
 	android:layout_width="match_parent"
 	android:layout_height="match_parent"
@@ -9,11 +8,11 @@
 
 	<de.hdodenhof.circleimageview.CircleImageView
 		android:id="@+id/avatarView"
+		style="@style/BriarAvatar"
 		android:layout_width="@dimen/dropdown_picture_size"
 		android:layout_height="@dimen/dropdown_picture_size"
 		android:layout_margin="@dimen/margin_small"
-		app:civ_border_color="@color/briar_primary"
-		app:civ_border_width="@dimen/avatar_border_width"/>
+		tools:src="@drawable/ic_launcher"/>
 
 	<TextView
 		android:id="@+id/nameView"

briar-android/res/layout/fragment_keyagreement_qr.xml

@@ -10,6 +10,11 @@
 		android:layout_width="match_parent"
 		android:layout_height="match_parent"/>
 
+	<org.briarproject.android.util.ViewfinderView
+		android:id="@+id/viewfinder_view"
+		android:layout_width="match_parent"
+		android:layout_height="match_parent"/>
+
 	<LinearLayout
 		android:layout_width="match_parent"
 		android:layout_height="match_parent"

briar-android/res/layout/introduction_message.xml

@@ -24,6 +24,7 @@
 
 			<de.hdodenhof.circleimageview.CircleImageView
 				android:id="@+id/avatarContact1"
+				style="@style/BriarAvatar"
 				android:layout_width="@dimen/listitem_picture_size"
 				android:layout_height="@dimen/listitem_picture_size"
 				android:layout_centerHorizontal="true"
@@ -31,8 +32,6 @@
 				android:layout_marginRight="@dimen/listitem_horizontal_margin"
 				android:layout_toLeftOf="@+id/introductionIcon"
 				android:layout_toStartOf="@+id/introductionIcon"
-				app:civ_border_color="@color/briar_primary"
-				app:civ_border_width="@dimen/avatar_border_width"
 				tools:src="@drawable/ic_launcher"/>
 
 			<ImageView
@@ -45,6 +44,7 @@
 
 			<de.hdodenhof.circleimageview.CircleImageView
 				android:id="@+id/avatarContact2"
+				style="@style/BriarAvatar"
 				android:layout_width="@dimen/listitem_picture_size"
 				android:layout_height="@dimen/listitem_picture_size"
 				android:layout_centerHorizontal="true"
@@ -53,8 +53,6 @@
 				android:layout_toEndOf="@+id/introductionIcon"
 				android:layout_toRightOf="@+id/introductionIcon"
 				android:transitionName="avatar"
-				app:civ_border_color="@color/briar_primary"
-				app:civ_border_width="@dimen/avatar_border_width"
 				tools:src="@drawable/ic_launcher"/>
 
 		</RelativeLayout>

briar-android/res/layout/list_item_contact.xml

@@ -10,36 +10,55 @@
 	<RelativeLayout
 		android:layout_width="match_parent"
 		android:layout_height="wrap_content"
-		android:paddingTop="@dimen/listitem_horizontal_margin"
-		android:paddingBottom="@dimen/listitem_horizontal_margin"
 		android:background="?attr/selectableItemBackground"
+		android:paddingBottom="@dimen/listitem_horizontal_margin"
+		android:paddingTop="@dimen/listitem_horizontal_margin"
 		>
 
-		<de.hdodenhof.circleimageview.CircleImageView
-			android:id="@+id/avatarView"
-			android:layout_width="@dimen/listitem_picture_size"
-			android:layout_height="@dimen/listitem_picture_size"
+		<FrameLayout
+			android:id="@+id/avatarFrameView"
+			android:layout_width="@dimen/listitem_picture_frame_size"
+			android:layout_height="@dimen/listitem_picture_frame_size"
 			android:layout_alignParentLeft="true"
 			android:layout_alignParentStart="true"
 			android:layout_centerVertical="true"
 			android:layout_marginLeft="@dimen/listitem_horizontal_margin"
-			android:layout_marginStart="@dimen/listitem_horizontal_margin"
-			android:transitionName="avatar"
-			app:civ_border_color="@color/briar_primary"
-			app:civ_border_width="@dimen/avatar_border_width"
-			tools:src="@drawable/ic_launcher"/>
+			android:layout_marginStart="@dimen/listitem_horizontal_margin">
+
+			<de.hdodenhof.circleimageview.CircleImageView
+				android:id="@+id/avatarView"
+				style="@style/BriarAvatar"
+				android:layout_width="@dimen/listitem_picture_size"
+				android:layout_height="@dimen/listitem_picture_size"
+				android:layout_gravity="bottom|left"
+				tools:src="@drawable/ic_launcher"/>
+
+			<TextView
+				android:id="@+id/unreadCountView"
+				android:layout_width="wrap_content"
+				android:layout_height="@dimen/unread_bubble_size"
+				android:layout_gravity="right|top"
+				android:background="@drawable/bubble"
+				android:gravity="center"
+				android:minWidth="@dimen/unread_bubble_size"
+				android:textColor="@color/briar_text_primary_inverse"
+				android:textSize="@dimen/unread_bubble_text_size"
+				android:textStyle="bold"
+				tools:text="123"/>
+
+		</FrameLayout>
 
 		<LinearLayout
 			android:id="@+id/textViews"
 			android:layout_width="wrap_content"
 			android:layout_height="wrap_content"
-			android:orientation="vertical"
 			android:layout_centerVertical="true"
 			android:layout_marginLeft="@dimen/listitem_horizontal_margin"
 			android:layout_marginStart="@dimen/listitem_horizontal_margin"
+			android:layout_toEndOf="@+id/avatarFrameView"
 			android:layout_toLeftOf="@+id/bulbView"
-			android:layout_toRightOf="@+id/avatarView"
-			android:layout_toEndOf="@+id/avatarView">
+			android:layout_toRightOf="@+id/avatarFrameView"
+			android:orientation="vertical">
 
 			<TextView
 				android:id="@+id/nameView"

briar-android/res/layout/list_item_contact_small.xml

@@ -0,0 +1,32 @@
+<?xml version="1.0" encoding="utf-8"?>
+<LinearLayout
+	xmlns:android="http://schemas.android.com/apk/res/android"
+	xmlns:tools="http://schemas.android.com/tools"
+	android:layout_width="match_parent"
+	android:layout_height="wrap_content"
+	android:orientation="horizontal"
+	android:paddingBottom="@dimen/margin_small"
+	android:paddingTop="@dimen/margin_small">
+
+	<de.hdodenhof.circleimageview.CircleImageView
+		android:id="@+id/avatarView"
+		style="@style/BriarAvatar"
+		android:layout_width="@dimen/listitem_picture_size_small"
+		android:layout_height="@dimen/listitem_picture_size_small"
+		android:layout_marginLeft="@dimen/listitem_horizontal_margin"
+		android:layout_marginStart="@dimen/listitem_horizontal_margin"
+		tools:src="@drawable/ic_launcher"/>
+
+	<TextView
+		android:id="@+id/nameView"
+		android:layout_width="wrap_content"
+		android:layout_height="wrap_content"
+		android:layout_gravity="center_vertical"
+		android:layout_marginLeft="@dimen/listitem_horizontal_margin"
+		android:layout_marginStart="@dimen/listitem_horizontal_margin"
+		android:maxLines="2"
+		android:textColor="@color/briar_text_primary"
+		android:textSize="@dimen/text_size_medium"
+		tools:text="This is a name of a contact"/>
+
+</LinearLayout>

briar-android/res/layout/list_item_selectable_contact.xml

@@ -14,6 +14,7 @@
 
 		<de.hdodenhof.circleimageview.CircleImageView
 			android:id="@+id/avatarView"
+			style="@style/BriarAvatar"
 			android:layout_width="@dimen/listitem_selectable_picture_size"
 			android:layout_height="@dimen/listitem_selectable_picture_size"
 			android:layout_alignParentLeft="true"
@@ -22,8 +23,6 @@
 			android:layout_marginLeft="@dimen/listitem_horizontal_margin"
 			android:layout_marginStart="@dimen/listitem_horizontal_margin"
 			android:transitionName="avatar"
-			app:civ_border_color="@color/briar_primary"
-			app:civ_border_width="@dimen/avatar_border_width"
 			tools:src="@drawable/ic_launcher"/>
 
 		<TextView

briar-android/res/layout/text_avatar_view.xml

@@ -1,18 +1,17 @@
 <?xml version="1.0" encoding="utf-8"?>
 <merge
 	xmlns:android="http://schemas.android.com/apk/res/android"
-	xmlns:tools="http://schemas.android.com/tools"
-	xmlns:app="http://schemas.android.com/apk/res-auto">
+	xmlns:app="http://schemas.android.com/apk/res-auto"
+	xmlns:tools="http://schemas.android.com/tools">
 
 	<de.hdodenhof.circleimageview.CircleImageView
 		android:id="@+id/avatarBackground"
+		style="@style/BriarAvatar"
 		android:layout_width="@dimen/avatar_forum_size"
 		android:layout_height="@dimen/avatar_forum_size"
 		android:layout_gravity="center"
 		android:src="@android:color/transparent"
-		app:civ_fill_color="@color/briar_button_positive"
-		app:civ_border_color="@color/briar_primary"
-		app:civ_border_width="@dimen/avatar_border_width"/>
+		app:civ_fill_color="@color/briar_button_positive"/>
 
 	<android.support.v7.widget.AppCompatTextView
 		android:id="@+id/textAvatarView"
@@ -29,4 +28,3 @@
 		tools:text="T"/>
 
 </merge>
-

briar-android/res/menu/forum_actions.xml

@@ -15,6 +15,11 @@
 		android:title="@string/forum_share_button"
 		app:showAsAction="ifRoom"/>
 
+	<item
+		android:id="@+id/action_forum_sharing_status"
+		android:title="@string/forum_sharing_status"
+		app:showAsAction="never"/>
+
 	<item
 		android:id="@+id/action_forum_delete"
 		android:icon="@drawable/action_delete_white"

briar-android/res/values/color.xml

@@ -18,7 +18,7 @@
 	<color name="horizontal_border">#CCCCCC</color>
 	<color name="forums_available_background">@color/briar_gold</color>
 	<color name="no_private_messages">#AAAAAA</color>
-	<color name="forum_avatar_shadow">#b3b3b3</color>
+	<color name="forum_avatar_shadow">#99000000</color>
 
 	<color name="briar_primary">@color/briar_blue</color>
 	<color name="briar_primary_dark">@color/briar_blue_dark</color>
@@ -36,10 +36,17 @@
 
 	<!-- this is needed as preference_category_material layout uses this color as the text color -->
 	<color name="preference_fallback_accent_color">@color/briar_accent</color>
+	<color name="divider">#c1c1c1</color>
 	<color name="default_separator">#000000</color>
 	<color name="default_separator_inverted">#ffffff</color>
 	<color name="menu_background">#FFFFFF</color>
 
 	<color name="spinner_border">#61000000</color> <!-- 38% Black -->
 	<color name="spinner_arrow">@color/briar_blue_dark</color>
+
+	<!-- ViewfinderView -->
+	<color name="possible_result_points">#c0ffbd21</color> <!-- Material Yellow 700 with alpha -->
+	<color name="result_view">#b0000000</color>
+	<color name="viewfinder_laser">#d50000</color> <!-- Red accent 700 -->
+	<color name="viewfinder_mask">#60000000</color>
 </resources>

briar-android/res/values/dimens.xml

@@ -26,10 +26,17 @@
 	<dimen name="listitem_height_one_line_avatar">56dp</dimen>
 	<dimen name="listitem_height_contact_selector">68dp</dimen>
 	<dimen name="listitem_picture_size">48dp</dimen>
+	<dimen name="listitem_picture_size_small">23dp</dimen>
+	<dimen name="listitem_picture_frame_size">50dp</dimen>
 	<dimen name="listitem_selectable_picture_size">40dp</dimen>
 	<dimen name="dropdown_picture_size">32dp</dimen>
 	<dimen name="avatar_forum_size">48dp</dimen>
-	<dimen name="avatar_border_width">1dp</dimen>
+	<dimen name="avatar_border_width">2dp</dimen>
+
+	<dimen name="unread_bubble_text_size">12sp</dimen>
+	<dimen name="unread_bubble_border_width">2dp</dimen>
+	<dimen name="unread_bubble_padding_horizontal">6dp</dimen>
+	<dimen name="unread_bubble_size">19dp</dimen>
 
 	<dimen name="message_bubble_margin_tail">14dp</dimen>
 	<dimen name="message_bubble_margin_non_tail">51dp</dimen>

briar-android/res/values/strings.xml

@@ -80,6 +80,7 @@
 	<string name="show_forums">Show</string>
 	<string name="forum_leave">Leave Forum</string>
 	<string name="forum_left_toast">Left Forum</string>
+	<string name="forum_sharing_status">Sharing Status</string>
 	<string name="no_forum_posts">No posts</string>
 	<string name="no_unread_posts">no unread posts</string>
 	<plurals name="unread_posts">
@@ -109,6 +110,9 @@
 	<string name="forum_joined_toast">Joined Forum</string>
 	<string name="forum_declined_toast">Forum Invitation Declined</string>
 	<string name="shared_by_format">Shared by %s</string>
+	<string name="forum_shared_by">Shared by</string>
+	<string name="forum_shared_with">Shared with</string>
+	<string name="nobody">Nobody</string>
 	<string name="no_contacts_prompt">You don\'t have any contacts. Add a contact now?</string>
 	<string name="add_button">Add</string>
 	<string name="cancel_button">Cancel</string>

briar-android/res/values/styles.xml

@@ -93,7 +93,7 @@
 	</style>
 
 	<style name="Divider">
-		<item name="android:background">?android:attr/listDivider</item>
+		<item name="android:background">@color/divider</item>
 	</style>
 
 	<style name="Divider.Horizontal" parent="Divider">
@@ -112,6 +112,14 @@
 		<item name="android:layout_height">1dp</item>
 	</style>
 
+	<style name="BriarAvatar">
+		<item name="civ_border_width">@dimen/avatar_border_width</item>
+		<item name="civ_border_color">@color/briar_primary</item>
+
+		<!-- Remove when we are using 'de.hdodenhof:circleimageview:2.1.0' -->
+		<item name="civ_border_overlay">true</item>
+	</style>
+
 	<style name="NavMenuButton" parent="Widget.AppCompat.Button.Borderless.Colored">
 		<item name="android:textSize">@dimen/text_size_medium</item>
 		<item name="android:textColor">@android:color/tertiary_text_light</item>

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

@@ -7,6 +7,7 @@ import org.briarproject.android.forum.AvailableForumsActivity;
 import org.briarproject.android.forum.ContactSelectorFragment;
 import org.briarproject.android.forum.CreateForumActivity;
 import org.briarproject.android.forum.ForumActivity;
+import org.briarproject.android.forum.ForumSharingStatusActivity;
 import org.briarproject.android.forum.ReadForumPostActivity;
 import org.briarproject.android.forum.ShareForumActivity;
 import org.briarproject.android.forum.ShareForumMessageFragment;
@@ -59,6 +60,8 @@ public interface ActivityComponent {
 
 	void inject(ShareForumActivity activity);
 
+	void inject(ForumSharingStatusActivity activity);
+
 	void inject(ReadForumPostActivity activity);
 
 	void inject(ForumActivity activity);

briar-android/src/org/briarproject/android/ExpiredActivity.java

@@ -1,17 +1,12 @@
 package org.briarproject.android;
 
-import static android.view.Gravity.CENTER;
-import static android.view.WindowManager.LayoutParams.FLAG_SECURE;
-import static org.briarproject.android.TestingConstants.PREVENT_SCREENSHOTS;
-import static org.briarproject.android.util.CommonLayoutParams.MATCH_MATCH;
-
-import org.briarproject.R;
-import org.briarproject.android.util.LayoutUtils;
-
 import android.app.Activity;
 import android.os.Bundle;
-import android.widget.LinearLayout;
-import android.widget.TextView;
+
+import org.briarproject.R;
+
+import static android.view.WindowManager.LayoutParams.FLAG_SECURE;
+import static org.briarproject.android.TestingConstants.PREVENT_SCREENSHOTS;
 
 public class ExpiredActivity extends Activity {
 
@@ -21,19 +16,6 @@ public class ExpiredActivity extends Activity {
 
 		if (PREVENT_SCREENSHOTS) getWindow().addFlags(FLAG_SECURE);
 
-		LinearLayout layout = new LinearLayout(this);
-		layout.setLayoutParams(MATCH_MATCH);
-		layout.setGravity(CENTER);
-
-		int pad = LayoutUtils.getPadding(this);
-
-		TextView warning = new TextView(this);
-		warning.setGravity(CENTER);
-		warning.setTextSize(18);
-		warning.setPadding(pad, pad, pad, pad);
-		warning.setText(R.string.expiry_warning);
-		layout.addView(warning);
-
-		setContentView(layout);
+		setContentView(R.layout.activity_expired);
 	}
 }

briar-android/src/org/briarproject/android/contact/BaseContactListAdapter.java

@@ -1,6 +1,7 @@
 package org.briarproject.android.contact;
 
 import android.content.Context;
+import android.support.v4.view.ViewCompat;
 import android.support.v7.util.SortedList;
 import android.support.v7.widget.RecyclerView;
 import android.view.View;
@@ -11,6 +12,7 @@ import android.widget.TextView;
 import org.briarproject.R;
 import org.briarproject.api.contact.ContactId;
 import org.briarproject.api.identity.Author;
+import org.briarproject.util.StringUtils;
 
 import java.util.List;
 
@@ -48,6 +50,9 @@ public abstract class BaseContactListAdapter<VH extends BaseContactListAdapter.B
 				if (listener != null) listener.onItemClick(ui.avatar, item);
 			}
 		});
+
+		ViewCompat.setTransitionName(ui.avatar, "avatar" +
+				StringUtils.toHexString(item.getGroupId().getBytes()));
 	}
 
 	@Override

briar-android/src/org/briarproject/android/contact/ContactListAdapter.java

@@ -2,6 +2,7 @@ package org.briarproject.android.contact;
 
 import android.content.Context;
 import android.support.v4.content.ContextCompat;
+import android.support.v4.view.ViewCompat;
 import android.text.format.DateUtils;
 import android.view.LayoutInflater;
 import android.view.View;
@@ -10,6 +11,7 @@ import android.widget.ImageView;
 import android.widget.TextView;
 
 import org.briarproject.R;
+import org.briarproject.util.StringUtils;
 
 public class ContactListAdapter
 		extends BaseContactListAdapter<ContactListAdapter.ContactHolder> {
@@ -32,18 +34,13 @@ public class ContactListAdapter
 
 		ContactListItem item = getItem(position);
 
-		// name and unread count
-		String contactName = item.getContact().getAuthor().getName();
+		// unread count
 		int unread = item.getUnreadCount();
 		if (unread > 0) {
-			// TODO show these in a bubble on top of the avatar
-			ui.name.setText(contactName + " (" + unread + ")");
-
-			// different background for contacts with unread messages
-			ui.layout.setBackgroundColor(
-					ContextCompat.getColor(ctx, R.color.unread_background));
+			ui.unread.setText(String.valueOf(unread));
+			ui.unread.setVisibility(View.VISIBLE);
 		} else {
-			ui.name.setText(contactName);
+			ui.unread.setVisibility(View.INVISIBLE);
 		}
 
 		// date of last message
@@ -62,12 +59,16 @@ public class ContactListAdapter
 		} else {
 			ui.bulb.setImageResource(R.drawable.contact_disconnected);
 		}
+
+		ViewCompat.setTransitionName(ui.bulb,
+				"bulb" + StringUtils.toHexString(item.getGroupId().getBytes()));
 	}
 
 	protected static class ContactHolder
 			extends BaseContactListAdapter.BaseContactHolder {
 
 		public final ImageView bulb;
+		public final TextView unread;
 		public final TextView date;
 		public final TextView identity;
 
@@ -75,6 +76,7 @@ public class ContactListAdapter
 			super(v);
 
 			bulb = (ImageView) v.findViewById(R.id.bulbView);
+			unread = (TextView) v.findViewById(R.id.unreadCountView);
 			date = (TextView) v.findViewById(R.id.dateView);
 			identity = (TextView) v.findViewById(R.id.identityView);
 		}

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

@@ -1,11 +1,13 @@
 package org.briarproject.android.contact;
 
 import android.content.Intent;
-import android.os.Build;
 import android.os.Bundle;
 import android.support.annotation.Nullable;
 import android.support.design.widget.FloatingActionButton;
+import android.support.v4.app.ActivityCompat;
 import android.support.v4.app.ActivityOptionsCompat;
+import android.support.v4.util.Pair;
+import android.support.v4.view.ViewCompat;
 import android.support.v7.widget.LinearLayoutManager;
 import android.view.LayoutInflater;
 import android.view.View;
@@ -48,6 +50,7 @@ import java.util.logging.Logger;
 
 import javax.inject.Inject;
 
+import static android.support.v4.app.ActivityOptionsCompat.makeSceneTransitionAnimation;
 import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
 import static org.briarproject.android.BriarActivity.GROUP_ID;
@@ -107,16 +110,22 @@ public class ContactListFragment extends BaseFragment implements EventListener {
 								ConversationActivity.class);
 						i.putExtra(GROUP_ID, groupId.getBytes());
 
-						if (Build.VERSION.SDK_INT >= 16) {
-							ActivityOptionsCompat options =
-									ActivityOptionsCompat.
-											makeSceneTransitionAnimation(
-													getActivity(),
-													view, "avatar");
-							getActivity().startActivity(i, options.toBundle());
-						} else {
-							startActivity(i);
-						}
+						ContactListAdapter.ContactHolder holder =
+								(ContactListAdapter.ContactHolder) list
+										.getRecyclerView()
+										.findViewHolderForAdapterPosition(
+												adapter.findItemPosition(item));
+						Pair<View, String> avatar =
+								Pair.create((View) holder.avatar, ViewCompat
+										.getTransitionName(holder.avatar));
+						Pair<View, String> bulb =
+								Pair.create((View) holder.bulb, ViewCompat
+										.getTransitionName(holder.bulb));
+						ActivityOptionsCompat options =
+								makeSceneTransitionAnimation(getActivity(),
+										avatar, bulb);
+						ActivityCompat.startActivity(getActivity(), i,
+								options.toBundle());
 					}
 				};
 

briar-android/src/org/briarproject/android/contact/ContactListItem.java

@@ -30,7 +30,7 @@ public class ContactListItem {
 	}
 
 	void setMessages(Collection<ConversationItem> messages) {
-		empty = messages.isEmpty();
+		empty = messages == null || messages.isEmpty();
 		timestamp = 0;
 		unread = 0;
 		if (!empty) {

briar-android/src/org/briarproject/android/contact/ConversationActivity.java

@@ -6,6 +6,7 @@ import android.os.Bundle;
 import android.support.v4.app.ActivityCompat;
 import android.support.v4.app.ActivityOptionsCompat;
 import android.support.v4.content.ContextCompat;
+import android.support.v4.view.ViewCompat;
 import android.support.v7.app.ActionBar;
 import android.support.v7.app.AlertDialog;
 import android.support.v7.widget.LinearLayoutManager;
@@ -156,6 +157,10 @@ public class ConversationActivity extends BriarActivity
 			ab.setDisplayShowTitleEnabled(false);
 		}
 
+		String hexGroupId = StringUtils.toHexString(b);
+		ViewCompat.setTransitionName(toolbarAvatar, "avatar" + hexGroupId);
+		ViewCompat.setTransitionName(toolbarStatus, "bulb" + hexGroupId);
+
 		adapter = new ConversationAdapter(this, this);
 		list = (BriarRecyclerView) findViewById(R.id.conversationView);
 		list.setLayoutManager(new LinearLayoutManager(this));
@@ -207,7 +212,7 @@ public class ConversationActivity extends BriarActivity
 		// Handle presses on the action bar items
 		switch (item.getItemId()) {
 			case android.R.id.home:
-				supportFinishAfterTransition();
+				onBackPressed();
 				return true;
 			case R.id.action_introduction:
 				if (contactId == null) return false;
@@ -227,6 +232,13 @@ public class ConversationActivity extends BriarActivity
 		}
 	}
 
+	@Override
+	public void onBackPressed() {
+		// FIXME disabled exit transition, because it doesn't work for some reason
+		//supportFinishAfterTransition();
+		finish();
+	}
+
 	private void loadData() {
 		runOnDbThread(new Runnable() {
 			@Override

briar-android/src/org/briarproject/android/forum/AvailableForumsActivity.java

@@ -153,7 +153,7 @@ public class AvailableForumsActivity extends BriarActivity
 
 	@Override
 	public void onItemClick(AvailableForumsItem item, boolean accept) {
-		respondToInvitation(item.getForum(), accept);
+		respondToInvitation(item, accept);
 
 		// show toast
 		int res = R.string.forum_declined_toast;
@@ -161,12 +161,16 @@ public class AvailableForumsActivity extends BriarActivity
 		Toast.makeText(this, res, LENGTH_SHORT).show();
 	}
 
-	private void respondToInvitation(final Forum f, final boolean accept) {
+	private void respondToInvitation(final AvailableForumsItem item,
+			final boolean accept) {
 		runOnDbThread(new Runnable() {
 			@Override
 			public void run() {
 				try {
-					forumSharingManager.respondToInvitation(f, accept);
+					Forum f = item.getForum();
+					for (Contact c : item.getContacts()) {
+						forumSharingManager.respondToInvitation(f, c, accept);
+					}
 				} catch (DbException e) {
 					if (LOG.isLoggable(WARNING))
 						LOG.log(WARNING, e.toString(), e);

briar-android/src/org/briarproject/android/forum/CreateForumActivity.java

@@ -129,8 +129,7 @@ public class CreateForumActivity extends BriarActivity
 			public void run() {
 				try {
 					long now = System.currentTimeMillis();
-					Forum f = forumManager.createForum(name);
-					forumManager.addForum(f);
+					Forum f = forumManager.addForum(name);
 					long duration = System.currentTimeMillis() - now;
 					if (LOG.isLoggable(INFO))
 						LOG.info("Storing forum took " + duration + " ms");

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

@@ -153,6 +153,9 @@ public class ForumActivity extends BriarActivity implements EventListener,
 
 	@Override
 	public boolean onOptionsItemSelected(final MenuItem item) {
+		ActivityOptionsCompat options = ActivityOptionsCompat
+				.makeCustomAnimation(this, android.R.anim.slide_in_left,
+						android.R.anim.slide_out_right);
 		// Handle presses on the action bar items
 		switch (item.getItemId()) {
 			case R.id.action_forum_compose_post:
@@ -166,13 +169,16 @@ public class ForumActivity extends BriarActivity implements EventListener,
 				Intent i2 = new Intent(this, ShareForumActivity.class);
 				i2.setFlags(FLAG_ACTIVITY_CLEAR_TOP | FLAG_ACTIVITY_SINGLE_TOP);
 				i2.putExtra(GROUP_ID, groupId.getBytes());
-				ActivityOptionsCompat options = ActivityOptionsCompat
-						.makeCustomAnimation(this, android.R.anim.slide_in_left,
-								android.R.anim.slide_out_right);
 				ActivityCompat
 						.startActivityForResult(this, i2, REQUEST_FORUM_SHARED,
 								options.toBundle());
 				return true;
+			case R.id.action_forum_sharing_status:
+				Intent i3 = new Intent(this, ForumSharingStatusActivity.class);
+				i3.setFlags(FLAG_ACTIVITY_CLEAR_TOP | FLAG_ACTIVITY_SINGLE_TOP);
+				i3.putExtra(GROUP_ID, groupId.getBytes());
+				ActivityCompat.startActivity(this, i3, options.toBundle());
+				return true;
 			case R.id.action_forum_delete:
 				showUnsubscribeDialog();
 				return true;

briar-android/src/org/briarproject/android/forum/ForumSharingStatusActivity.java

@@ -0,0 +1,169 @@
+package org.briarproject.android.forum;
+
+import android.content.Intent;
+import android.os.Bundle;
+import android.support.v7.widget.LinearLayoutManager;
+import android.view.MenuItem;
+
+import org.briarproject.R;
+import org.briarproject.android.ActivityComponent;
+import org.briarproject.android.BriarActivity;
+import org.briarproject.android.contact.ContactListItem;
+import org.briarproject.android.util.BriarRecyclerView;
+import org.briarproject.api.contact.Contact;
+import org.briarproject.api.db.DbException;
+import org.briarproject.api.forum.ForumSharingManager;
+import org.briarproject.api.identity.IdentityManager;
+import org.briarproject.api.identity.LocalAuthor;
+import org.briarproject.api.sync.GroupId;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.List;
+import java.util.logging.Logger;
+
+import javax.inject.Inject;
+
+import static java.util.logging.Level.WARNING;
+
+public class ForumSharingStatusActivity extends BriarActivity {
+
+	private GroupId groupId;
+	private BriarRecyclerView sharedByList, sharedWithList;
+	private ForumSharingStatusAdapter sharedByAdapter, sharedWithAdapter;
+
+	// Fields that are accessed from background threads must be volatile
+	@Inject
+	protected volatile ForumSharingManager forumSharingManager;
+	@Inject
+	protected volatile IdentityManager identityManager;
+
+	public final static String TAG = "ForumSharingStatusActivity";
+	private static final Logger LOG = Logger.getLogger(TAG);
+
+	@Override
+	public void onCreate(Bundle savedInstanceState) {
+		super.onCreate(savedInstanceState);
+
+		setContentView(R.layout.activity_forum_sharing_status);
+
+		Intent i = getIntent();
+		byte[] b = i.getByteArrayExtra(GROUP_ID);
+		if (b == null) throw new IllegalStateException("No GroupId");
+		groupId = new GroupId(b);
+
+		sharedByList = (BriarRecyclerView) findViewById(R.id.sharedByView);
+		sharedByAdapter = new ForumSharingStatusAdapter(this);
+		sharedByList.setLayoutManager(new LinearLayoutManager(this));
+		sharedByList.setAdapter(sharedByAdapter);
+		sharedByList.setEmptyText(getString(R.string.nobody));
+
+		sharedWithList = (BriarRecyclerView) findViewById(R.id.sharedWithView);
+		sharedWithAdapter = new ForumSharingStatusAdapter(this);
+		sharedWithList.setLayoutManager(new LinearLayoutManager(this));
+		sharedWithList.setAdapter(sharedWithAdapter);
+		sharedWithList.setEmptyText(getString(R.string.nobody));
+	}
+
+	@Override
+	public void onResume() {
+		super.onResume();
+
+		loadSharedBy();
+		loadSharedWith();
+	}
+
+	@Override
+	public boolean onOptionsItemSelected(final MenuItem item) {
+		// Handle presses on the action bar items
+		switch (item.getItemId()) {
+			case android.R.id.home:
+				onBackPressed();
+				return true;
+			default:
+				return super.onOptionsItemSelected(item);
+		}
+	}
+
+	@Override
+	public void injectActivity(ActivityComponent component) {
+		component.inject(this);
+	}
+
+	private void loadSharedBy() {
+		dbController.runOnDbThread(new Runnable() {
+			@Override
+			public void run() {
+				List<ContactListItem> contactItems = new ArrayList<>();
+				try {
+					Collection<Contact> contacts =
+							forumSharingManager.getSharedBy(groupId);
+					for (Contact c : contacts) {
+						LocalAuthor localAuthor = identityManager
+								.getLocalAuthor(c.getLocalAuthorId());
+						ContactListItem item =
+								new ContactListItem(c, localAuthor, false, null,
+										null);
+						contactItems.add(item);
+					}
+				} catch (DbException e) {
+					if (LOG.isLoggable(WARNING))
+						LOG.log(WARNING, e.toString(), e);
+				}
+				displaySharedBy(contactItems);
+			}
+		});
+	}
+
+	private void displaySharedBy(final List<ContactListItem> contacts) {
+		runOnUiThread(new Runnable() {
+			@Override
+			public void run() {
+				if (contacts.isEmpty()) {
+					sharedByList.showData();
+				} else {
+					sharedByAdapter.addAll(contacts);
+				}
+			}
+		});
+	}
+
+	private void loadSharedWith() {
+		dbController.runOnDbThread(new Runnable() {
+			@Override
+			public void run() {
+				List<ContactListItem> contactItems = new ArrayList<>();
+				try {
+					Collection<Contact> contacts =
+							forumSharingManager.getSharedWith(groupId);
+					for (Contact c : contacts) {
+						LocalAuthor localAuthor = identityManager
+								.getLocalAuthor(c.getLocalAuthorId());
+						ContactListItem item =
+								new ContactListItem(c, localAuthor, false, null,
+										null);
+						contactItems.add(item);
+					}
+				} catch (DbException e) {
+					if (LOG.isLoggable(WARNING))
+						LOG.log(WARNING, e.toString(), e);
+				}
+				displaySharedWith(contactItems);
+			}
+		});
+	}
+
+	private void displaySharedWith(final List<ContactListItem> contacts) {
+		runOnUiThread(new Runnable() {
+			@Override
+			public void run() {
+				if (contacts.isEmpty()) {
+					sharedWithList.showData();
+				} else {
+					sharedWithAdapter.addAll(contacts);
+				}
+			}
+		});
+	}
+
+}

briar-android/src/org/briarproject/android/forum/ForumSharingStatusAdapter.java

@@ -0,0 +1,36 @@
+package org.briarproject.android.forum;
+
+import android.content.Context;
+import android.support.v4.content.ContextCompat;
+import android.text.format.DateUtils;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+import android.widget.ImageView;
+import android.widget.TextView;
+
+import org.briarproject.R;
+import org.briarproject.android.contact.BaseContactListAdapter;
+import org.briarproject.android.contact.ContactListItem;
+
+public class ForumSharingStatusAdapter
+		extends BaseContactListAdapter<BaseContactListAdapter.BaseContactHolder> {
+
+	public ForumSharingStatusAdapter(Context context) {
+		super(context, null);
+	}
+
+	@Override
+	public BaseContactHolder onCreateViewHolder(ViewGroup viewGroup, int i) {
+		View v = LayoutInflater.from(viewGroup.getContext()).inflate(
+				R.layout.list_item_contact_small, viewGroup, false);
+
+		return new BaseContactHolder(v);
+	}
+
+	@Override
+	public int compareContactListItems(ContactListItem c1, ContactListItem c2) {
+		return compareByName(c1, c2);
+	}
+
+}

briar-android/src/org/briarproject/android/identity/CreateIdentityActivity.java

@@ -2,12 +2,14 @@ package org.briarproject.android.identity;
 
 import android.content.Intent;
 import android.os.Bundle;
+import android.support.design.widget.TextInputLayout;
+import android.text.Editable;
+import android.text.TextWatcher;
 import android.view.KeyEvent;
 import android.view.View;
 import android.view.View.OnClickListener;
 import android.widget.Button;
 import android.widget.EditText;
-import android.widget.LinearLayout;
 import android.widget.ProgressBar;
 import android.widget.TextView;
 import android.widget.TextView.OnEditorActionListener;
@@ -16,7 +18,7 @@ import android.widget.Toast;
 import org.briarproject.R;
 import org.briarproject.android.ActivityComponent;
 import org.briarproject.android.BriarActivity;
-import org.briarproject.android.util.LayoutUtils;
+import org.briarproject.android.util.AndroidUtils;
 import org.briarproject.api.crypto.CryptoComponent;
 import org.briarproject.api.crypto.CryptoExecutor;
 import org.briarproject.api.crypto.KeyPair;
@@ -31,18 +33,11 @@ import java.util.logging.Logger;
 
 import javax.inject.Inject;
 
-import static android.text.InputType.TYPE_CLASS_TEXT;
-import static android.text.InputType.TYPE_TEXT_FLAG_CAP_WORDS;
-import static android.view.Gravity.CENTER;
-import static android.view.Gravity.CENTER_HORIZONTAL;
 import static android.view.View.GONE;
 import static android.view.View.VISIBLE;
-import static android.widget.LinearLayout.VERTICAL;
 import static android.widget.Toast.LENGTH_LONG;
 import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
-import static org.briarproject.android.util.CommonLayoutParams.MATCH_MATCH;
-import static org.briarproject.android.util.CommonLayoutParams.WRAP_WRAP;
 import static org.briarproject.api.identity.AuthorConstants.MAX_AUTHOR_NAME_LENGTH;
 
 public class CreateIdentityActivity extends BriarActivity
@@ -55,10 +50,10 @@ public class CreateIdentityActivity extends BriarActivity
 	@CryptoExecutor
 	protected Executor cryptoExecutor;
 
+	private TextInputLayout nicknameInput;
 	private EditText nicknameEntry;
 	private Button createIdentityButton;
 	private ProgressBar progress;
-	private TextView feedback;
 
 	// Fields that are accessed from background threads must be volatile
 	@Inject
@@ -71,52 +66,32 @@ public class CreateIdentityActivity extends BriarActivity
 	@Override
 	public void onCreate(Bundle state) {
 		super.onCreate(state);
-		LinearLayout layout = new LinearLayout(this);
-		layout.setLayoutParams(MATCH_MATCH);
-		layout.setOrientation(VERTICAL);
-		layout.setGravity(CENTER_HORIZONTAL);
-		int pad = LayoutUtils.getPadding(this);
-		layout.setPadding(pad, pad, pad, pad);
 
-		TextView chooseNickname = new TextView(this);
-		chooseNickname.setGravity(CENTER);
-		chooseNickname.setTextSize(18);
-		chooseNickname.setText(R.string.choose_nickname);
-		layout.addView(chooseNickname);
+		setContentView(R.layout.activity_create_identity);
 
-		nicknameEntry = new EditText(this) {
+		nicknameInput = (TextInputLayout) findViewById(R.id.nicknameInputLayout);
+		nicknameEntry = (EditText) findViewById(R.id.nicknameEntry);
+		nicknameEntry.addTextChangedListener(new TextWatcher() {
 			@Override
-			protected void onTextChanged(CharSequence text, int start,
-					int lengthBefore, int lengthAfter) {
+			public void beforeTextChanged(CharSequence s, int start, int count,
+					int after) {}
+
+			@Override
+			public void onTextChanged(CharSequence s, int start, int before,
+					int count) {
 				enableOrDisableCreateButton();
 			}
-		};
-		nicknameEntry.setId(1);
-		nicknameEntry.setMaxLines(1);
-		int inputType = TYPE_CLASS_TEXT | TYPE_TEXT_FLAG_CAP_WORDS;
-		nicknameEntry.setInputType(inputType);
+
+			@Override
+			public void afterTextChanged(Editable s) {}
+		});
 		nicknameEntry.setOnEditorActionListener(this);
-		layout.addView(nicknameEntry);
 
-		feedback = new TextView(this);
-		feedback.setGravity(CENTER);
-		feedback.setPadding(0, pad, 0, pad);
-		layout.addView(feedback);
+		createIdentityButton = (Button) findViewById(R.id.createIdentityButton);
+		if (createIdentityButton != null)
+			createIdentityButton.setOnClickListener(this);
 
-		createIdentityButton = new Button(this);
-		createIdentityButton.setLayoutParams(WRAP_WRAP);
-		createIdentityButton.setText(R.string.create_identity_button);
-		createIdentityButton.setEnabled(false);
-		createIdentityButton.setOnClickListener(this);
-		layout.addView(createIdentityButton);
-
-		progress = new ProgressBar(this);
-		progress.setLayoutParams(WRAP_WRAP);
-		progress.setIndeterminate(true);
-		progress.setVisibility(GONE);
-		layout.addView(progress);
-
-		setContentView(layout);
+		progress = (ProgressBar) findViewById(R.id.progressBar);
 	}
 
 	@Override
@@ -139,10 +114,11 @@ public class CreateIdentityActivity extends BriarActivity
 		String nickname = nicknameEntry.getText().toString();
 		int length = StringUtils.toUtf8(nickname).length;
 		if (length > MAX_AUTHOR_NAME_LENGTH) {
-			feedback.setText(R.string.name_too_long);
+			String str = getString(R.string.name_too_long);
+			AndroidUtils.setError(nicknameInput, str, true);
 			return false;
 		}
-		feedback.setText("");
+		AndroidUtils.setError(nicknameInput, null, false);
 		return length > 0;
 	}
 
@@ -169,7 +145,7 @@ public class CreateIdentityActivity extends BriarActivity
 	}
 
 	private void storeLocalAuthor(final LocalAuthor a) {
-		runOnDbThread(new Runnable() {
+		dbController.runOnDbThread(new Runnable() {
 			@Override
 			public void run() {
 				try {

briar-android/src/org/briarproject/android/keyagreement/ShowQrCodeFragment.java

@@ -19,6 +19,8 @@ import android.widget.TextView;
 import android.widget.Toast;
 
 import com.google.zxing.Result;
+import com.google.zxing.ResultPoint;
+import com.google.zxing.ResultPointCallback;
 
 import org.briarproject.R;
 import org.briarproject.android.AndroidComponent;
@@ -27,6 +29,7 @@ import org.briarproject.android.fragment.BaseEventFragment;
 import org.briarproject.android.util.CameraView;
 import org.briarproject.android.util.QrCodeDecoder;
 import org.briarproject.android.util.QrCodeUtils;
+import org.briarproject.android.util.ViewfinderView;
 import org.briarproject.api.event.Event;
 import org.briarproject.api.event.KeyAgreementAbortedEvent;
 import org.briarproject.api.event.KeyAgreementFailedEvent;
@@ -55,7 +58,7 @@ import static java.util.logging.Level.WARNING;
 
 @SuppressWarnings("deprecation")
 public class ShowQrCodeFragment extends BaseEventFragment
-		implements QrCodeDecoder.ResultCallback {
+		implements QrCodeDecoder.ResultCallback, ResultPointCallback {
 
 	public static final String TAG = "ShowQrCodeFragment";
 
@@ -75,6 +78,7 @@ public class ShowQrCodeFragment extends BaseEventFragment
 	protected Executor ioExecutor;
 
 	private CameraView cameraView;
+	private ViewfinderView viewfinderView;
 	private View statusView;
 	private TextView status;
 	private ImageView qrCode;
@@ -109,9 +113,13 @@ public class ShowQrCodeFragment extends BaseEventFragment
 		super.onViewCreated(view, savedInstanceState);
 
 		cameraView = (CameraView) view.findViewById(R.id.camera_view);
+		viewfinderView =
+				(ViewfinderView) view.findViewById(R.id.viewfinder_view);
 		statusView = view.findViewById(R.id.status_container);
 		status = (TextView) view.findViewById(R.id.connect_status);
 		qrCode = (ImageView) view.findViewById(R.id.qr_code);
+
+		viewfinderView.setFrameProvider(cameraView);
 	}
 
 	@Override
@@ -120,7 +128,7 @@ public class ShowQrCodeFragment extends BaseEventFragment
 
 		getActivity().setRequestedOrientation(SCREEN_ORIENTATION_NOSENSOR);
 
-		decoder = new QrCodeDecoder(this);
+		decoder = new QrCodeDecoder(this, this);
 	}
 
 	@Override
@@ -219,6 +227,7 @@ public class ShowQrCodeFragment extends BaseEventFragment
 							getActivity().finish();
 						} else {
 							cameraView.start(camera, decoder, 0);
+							viewfinderView.drawViewfinder();
 						}
 					}
 				};
@@ -355,6 +364,11 @@ public class ShowQrCodeFragment extends BaseEventFragment
 		});
 	}
 
+	@Override
+	public void foundPossibleResultPoint(ResultPoint point) {
+		viewfinderView.addPossibleResultPoint(point);
+	}
+
 	private class BluetoothStateReceiver extends BroadcastReceiver {
 
 		@Override

briar-android/src/org/briarproject/android/util/BriarRecyclerView.java

@@ -120,10 +120,11 @@ public class BriarRecyclerView extends FrameLayout {
 				emptyView.setVisibility(VISIBLE);
 				recyclerView.setVisibility(INVISIBLE);
 			} else {
-				emptyView.setVisibility(INVISIBLE);
+				// use GONE here so empty view doesn't use space on small lists
+				emptyView.setVisibility(GONE);
 				recyclerView.setVisibility(VISIBLE);
 			}
-			progressBar.setVisibility(INVISIBLE);
+			progressBar.setVisibility(GONE);
 		}
 	}
 
@@ -131,4 +132,9 @@ public class BriarRecyclerView extends FrameLayout {
 		if (recyclerView == null) initViews();
 		recyclerView.scrollToPosition(position);
 	}
+
+	public RecyclerView getRecyclerView() {
+		return this.recyclerView;
+	}
+
 }

briar-android/src/org/briarproject/android/util/CameraView.java

@@ -1,6 +1,8 @@
 package org.briarproject.android.util;
 
 import android.content.Context;
+import android.graphics.Point;
+import android.graphics.Rect;
 import android.hardware.Camera;
 import android.hardware.Camera.AutoFocusCallback;
 import android.hardware.Camera.CameraInfo;
@@ -13,6 +15,7 @@ import android.view.SurfaceHolder;
 import android.view.SurfaceView;
 
 import java.io.IOException;
+import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
 import java.util.logging.Logger;
@@ -31,17 +34,25 @@ import static java.util.logging.Level.WARNING;
 
 @SuppressWarnings("deprecation")
 public class CameraView extends SurfaceView implements SurfaceHolder.Callback,
-		AutoFocusCallback {
+		AutoFocusCallback, ViewfinderView.FrameProvider {
 
 	private static final int AUTO_FOCUS_RETRY_DELAY = 5000; // Milliseconds
+	private static final int MIN_FRAME_SIZE = 240;
+	private static final int MAX_FRAME_SIZE = 675; // = 5/8 * 1080
 	private static final Logger LOG =
 			Logger.getLogger(CameraView.class.getName());
 
 	private Camera camera = null;
+	private Rect framingRect;
+	private Rect framingRectInPreview;
+	private Rect framingRectInSensor;
 	private PreviewConsumer previewConsumer = null;
 	private int displayOrientation = 0, surfaceWidth = 0, surfaceHeight = 0;
 	private boolean autoFocus = false, surfaceExists = false;
 
+	private Point cameraResolution;
+	private final Object cameraResolutionLock = new Object();
+
 	public CameraView(Context context) {
 		super(context);
 	}
@@ -184,6 +195,24 @@ public class CameraView extends SurfaceView implements SurfaceHolder.Callback,
 			LOG.info("No suitable focus mode");
 		}
 		params.setZoom(0);
+		if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.ICE_CREAM_SANDWICH) {
+			List<Camera.Area> areas = new ArrayList<>();
+			areas.add(new Camera.Area(getFramingRectInSensor(), 1000));
+			if (params.getMaxNumFocusAreas() > 0) {
+				if (LOG.isLoggable(INFO)) {
+					LOG.info("Focus areas supported: " +
+							params.getMaxNumFocusAreas());
+				}
+				params.setFocusAreas(areas);
+			}
+			if (params.getMaxNumMeteringAreas() > 0) {
+				if (LOG.isLoggable(INFO)) {
+					LOG.info("Metering areas supported: " +
+							params.getMaxNumMeteringAreas());
+				}
+				params.setMeteringAreas(areas);
+			}
+		}
 	}
 
 	private void setPreviewSize(Parameters params) {
@@ -222,6 +251,13 @@ public class CameraView extends SurfaceView implements SurfaceHolder.Callback,
 			if (LOG.isLoggable(INFO))
 				LOG.info("Best size " + bestSize.width + "x" + bestSize.height);
 			params.setPreviewSize(bestSize.width, bestSize.height);
+			synchronized (cameraResolutionLock) {
+				cameraResolution = new Point(bestSize.width, bestSize.height);
+			}
+		} else {
+			synchronized (cameraResolutionLock) {
+				cameraResolution = null;
+			}
 		}
 	}
 
@@ -276,4 +312,152 @@ public class CameraView extends SurfaceView implements SurfaceHolder.Callback,
 			LOG.log(WARNING, "Error retrying auto focus", e);
 		}
 	}
+
+	/**
+	 * Calculates the framing rect which the UI should draw to show the user where to place the
+	 * barcode. This target helps with alignment as well as forces the user to hold the device
+	 * far enough away to ensure the image will be in focus.
+	 *
+	 * @return The rectangle to draw on screen in window coordinates.
+	 */
+	@Override
+	public Rect getFramingRect() {
+		if (framingRect == null) {
+			framingRect = calculateFramingRect(true);
+			if (LOG.isLoggable(INFO))
+				LOG.info("Calculated framing rect: " + framingRect);
+		}
+		return framingRect;
+	}
+
+	/**
+	 * Calculates the framing rect which the UI should draw to show the user where to place the
+	 * barcode. This target helps with alignment as well as forces the user to hold the device
+	 * far enough away to ensure the image will be in focus.
+	 * <p/>
+	 * Adapted from the Zxing Barcode Scanner.
+	 *
+	 * @return The rectangle to draw on screen in window coordinates.
+	 */
+	private Rect calculateFramingRect(boolean withOrientation) {
+		if (camera == null) {
+			return null;
+		}
+		if (surfaceWidth == 0 || surfaceHeight == 0) {
+			// Called early, before the surface is ready
+			return null;
+		}
+
+		boolean portrait =
+				withOrientation && displayOrientation % 180 == 90;
+		int size = findDesiredDimensionInRange(
+				portrait ? surfaceWidth : surfaceHeight,
+				portrait ? surfaceHeight / 2 : surfaceWidth / 2,
+				MIN_FRAME_SIZE, MAX_FRAME_SIZE);
+
+		int leftOffset = portrait ?
+				(surfaceWidth - size) / 2 :
+				((surfaceWidth / 2) - size) / 2;
+		int topOffset = portrait ?
+				((surfaceHeight / 2) - size) / 2 :
+				(surfaceHeight - size) / 2;
+		return new Rect(leftOffset, topOffset, leftOffset + size,
+				topOffset + size);
+	}
+
+	/**
+	 * Calculates the square that fits best inside the given region.
+	 */
+	private static int findDesiredDimensionInRange(int side1, int side2,
+			int hardMin, int hardMax) {
+		if (LOG.isLoggable(INFO))
+			LOG.info("Finding framing dimension, side1 = " + side1 +
+					", side2 = " + side2);
+		int minSide = Math.min(side1, side2);
+		int dim = 5 * minSide / 8; // Target 5/8 of smallest side
+		if (dim < hardMin) {
+			if (hardMin > minSide) {
+				if (LOG.isLoggable(INFO))
+					LOG.info("Returning minimum side length: " + minSide);
+				return minSide;
+			} else {
+				if (LOG.isLoggable(INFO))
+					LOG.info("Returning hard minimum: " + hardMin);
+				return hardMin;
+			}
+		}
+		if (dim > hardMax) {
+			if (LOG.isLoggable(INFO))
+				LOG.info("Returning hard maximum: " + hardMax);
+			return hardMax;
+		}
+		if (LOG.isLoggable(INFO))
+			LOG.info("Returning desired dimension: " + dim);
+		return dim;
+	}
+
+	/**
+	 * Like {@link #getFramingRect} but coordinates are in terms of the preview
+	 * frame, not UI / screen.
+	 * <p/>
+	 * Adapted from the Zxing Barcode Scanner.
+	 *
+	 * @return {@link Rect} expressing QR code scan area in terms of the preview size
+	 */
+	@Override
+	public Rect getFramingRectInPreview() {
+		if (framingRectInPreview == null) {
+			Rect framingRect = getFramingRect();
+			if (framingRect == null) {
+				return null;
+			}
+			Rect rect = new Rect(framingRect);
+			Point cameraResolution = getCameraResolution();
+			if (cameraResolution == null || surfaceWidth == 0 ||
+					surfaceHeight == 0) {
+				// Called early, before the surface is ready
+				return null;
+			}
+			rect.left = rect.left * cameraResolution.x / surfaceWidth;
+			rect.right = rect.right * cameraResolution.x / surfaceWidth;
+			rect.top = rect.top * cameraResolution.y / surfaceHeight;
+			rect.bottom = rect.bottom * cameraResolution.y / surfaceHeight;
+			framingRectInPreview = rect;
+		}
+		return framingRectInPreview;
+	}
+
+	private Point getCameraResolution() {
+		Point ret;
+		synchronized (cameraResolutionLock) {
+			ret = new Point(cameraResolution);
+		}
+		return ret;
+	}
+
+	/**
+	 * Like {@link #getFramingRect} but coordinates are in terms of the sensor,
+	 * not UI / screen (ie. it is independent of orientation)
+	 *
+	 * @return {@link Rect} expressing QR code scan area in terms of the sensor
+	 */
+	private Rect getFramingRectInSensor() {
+		if (framingRectInSensor == null) {
+			Rect framingRect = calculateFramingRect(false);
+			if (framingRect == null) {
+				return null;
+			}
+			Rect rect = new Rect(framingRect);
+			if (surfaceWidth == 0 || surfaceHeight == 0) {
+				// Called early, before the surface is ready
+				return null;
+			}
+			rect.left = (rect.left * 2000 / surfaceWidth) - 1000;
+			rect.right = (rect.right * 2000 / surfaceWidth) - 1000;
+			rect.top = (rect.top * 2000 / surfaceHeight) - 1000;
+			rect.bottom = (rect.bottom * 2000 / surfaceHeight) - 1000;
+			framingRectInSensor = rect;
+		}
+		return framingRectInSensor;
+	}
 }

briar-android/src/org/briarproject/android/util/QrCodeDecoder.java

@@ -6,14 +6,18 @@ import android.hardware.Camera.Size;
 import android.os.AsyncTask;
 
 import com.google.zxing.BinaryBitmap;
+import com.google.zxing.DecodeHintType;
 import com.google.zxing.LuminanceSource;
 import com.google.zxing.PlanarYUVLuminanceSource;
 import com.google.zxing.Reader;
 import com.google.zxing.ReaderException;
 import com.google.zxing.Result;
+import com.google.zxing.ResultPointCallback;
 import com.google.zxing.common.HybridBinarizer;
 import com.google.zxing.qrcode.QRCodeReader;
 
+import java.util.HashMap;
+import java.util.Map;
 import java.util.logging.Logger;
 
 import static java.util.logging.Level.INFO;
@@ -26,11 +30,14 @@ public class QrCodeDecoder implements PreviewConsumer, PreviewCallback {
 
 	private final Reader reader = new QRCodeReader();
 	private final ResultCallback callback;
+	private final ResultPointCallback pointCallback;
 
 	private boolean stopped = false;
 
-	public QrCodeDecoder(ResultCallback callback) {
+	public QrCodeDecoder(ResultCallback callback,
+			ResultPointCallback pointCallback) {
 		this.callback = callback;
+		this.pointCallback = pointCallback;
 	}
 
 	public void start(Camera camera) {
@@ -72,9 +79,11 @@ public class QrCodeDecoder implements PreviewConsumer, PreviewCallback {
 			LuminanceSource src = new PlanarYUVLuminanceSource(data, width,
 					height, 0, 0, width, height, false);
 			BinaryBitmap bitmap = new BinaryBitmap(new HybridBinarizer(src));
+			Map<DecodeHintType, Object> hints = new HashMap<>();
+			hints.put(DecodeHintType.NEED_RESULT_POINT_CALLBACK, pointCallback);
 			Result result = null;
 			try {
-				result = reader.decode(bitmap);
+				result = reader.decode(bitmap, hints);
 			} catch (ReaderException e) {
 				return null; // No barcode found
 			} catch (RuntimeException e) {

briar-android/src/org/briarproject/android/util/ViewfinderView.java

@@ -0,0 +1,214 @@
+/*
+ * Copyright (C) 2008 ZXing authors
+ * Copyright (C) 2016 Sublime Software Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.briarproject.android.util;
+
+import android.annotation.SuppressLint;
+import android.content.Context;
+import android.content.res.Resources;
+import android.graphics.Bitmap;
+import android.graphics.Canvas;
+import android.graphics.Paint;
+import android.graphics.Rect;
+import android.util.AttributeSet;
+import android.view.View;
+
+import com.google.zxing.ResultPoint;
+
+import org.briarproject.R;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * This view is overlaid on top of the camera preview. It adds the viewfinder
+ * rectangle and partial transparency outside it, as well as the laser scanner
+ * animation and result points.
+ *
+ * @author dswitkin@google.com (Daniel Switkin)
+ */
+public final class ViewfinderView extends View {
+
+	private static final int[] SCANNER_ALPHA =
+			{0, 64, 128, 192, 255, 192, 128, 64};
+	private static final long ANIMATION_DELAY = 80L;
+	private static final int CURRENT_POINT_OPACITY = 0xA0;
+	private static final int MAX_RESULT_POINTS = 20;
+	private static final int POINT_SIZE = 6;
+
+	private FrameProvider frameProvider;
+	private final Paint paint;
+	private Bitmap resultBitmap;
+	private final int maskColor;
+	private final int resultColor;
+	private final int laserColor;
+	private final int resultPointColor;
+	private int scannerAlpha;
+	private List<ResultPoint> possibleResultPoints;
+	private List<ResultPoint> lastPossibleResultPoints;
+
+	// This constructor is used when the class is built from an XML resource.
+	public ViewfinderView(Context context, AttributeSet attrs) {
+		super(context, attrs);
+		if (isInEditMode()) {
+			paint = null;
+			maskColor = 0;
+			resultColor = 0;
+			laserColor = 0;
+			resultPointColor = 0;
+			return;
+		}
+
+		// Initialize these once for performance rather than calling them every
+		// time in onDraw().
+		paint = new Paint(Paint.ANTI_ALIAS_FLAG);
+		Resources resources = getResources();
+		maskColor = resources.getColor(R.color.viewfinder_mask);
+		resultColor = resources.getColor(R.color.result_view);
+		laserColor = resources.getColor(R.color.viewfinder_laser);
+		resultPointColor = resources.getColor(R.color.possible_result_points);
+		scannerAlpha = 0;
+		possibleResultPoints = new ArrayList<>(5);
+		lastPossibleResultPoints = null;
+	}
+
+	public void setFrameProvider(FrameProvider frameProvider) {
+		this.frameProvider = frameProvider;
+	}
+
+	@SuppressLint("DrawAllocation")
+	@Override
+	public void onDraw(Canvas canvas) {
+		if (frameProvider == null) {
+			return; // not ready yet, early draw before done configuring
+		}
+		Rect frame = this.frameProvider.getFramingRect();
+		Rect previewFrame = this.frameProvider.getFramingRectInPreview();
+		if (frame == null || previewFrame == null) {
+			return;
+		}
+		int width = canvas.getWidth();
+		int height = canvas.getHeight();
+
+		// Draw the exterior (i.e. outside the framing rect) darkened
+		paint.setColor(resultBitmap != null ? resultColor : maskColor);
+		canvas.drawRect(0, 0, width, frame.top, paint);
+		canvas.drawRect(0, frame.top, frame.left, frame.bottom + 1, paint);
+		canvas.drawRect(frame.right + 1, frame.top, width, frame.bottom + 1,
+				paint);
+		canvas.drawRect(0, frame.bottom + 1, width, height, paint);
+
+		if (resultBitmap != null) {
+			// Draw the opaque result bitmap over the scanning rectangle
+			paint.setAlpha(CURRENT_POINT_OPACITY);
+			canvas.drawBitmap(resultBitmap, null, frame, paint);
+		} else {
+
+			// Draw a red "laser scanner" line through the middle to show
+			// decoding is active
+			paint.setColor(laserColor);
+			paint.setAlpha(SCANNER_ALPHA[scannerAlpha]);
+			scannerAlpha = (scannerAlpha + 1) % SCANNER_ALPHA.length;
+			int middle = frame.height() / 2 + frame.top;
+			canvas.drawRect(frame.left + 2, middle - 1, frame.right - 1,
+					middle + 2, paint);
+
+			float scaleX = frame.width() / (float) previewFrame.width();
+			float scaleY = frame.height() / (float) previewFrame.height();
+
+			List<ResultPoint> currentPossible = possibleResultPoints;
+			List<ResultPoint> currentLast = lastPossibleResultPoints;
+			int frameLeft = frame.left;
+			int frameTop = frame.top;
+			if (currentPossible.isEmpty()) {
+				lastPossibleResultPoints = null;
+			} else {
+				possibleResultPoints = new ArrayList<>(5);
+				lastPossibleResultPoints = currentPossible;
+				paint.setAlpha(CURRENT_POINT_OPACITY);
+				paint.setColor(resultPointColor);
+				synchronized (currentPossible) {
+					for (ResultPoint point : currentPossible) {
+						canvas.drawCircle(
+								frameLeft + (int) (point.getX() * scaleX),
+								frameTop + (int) (point.getY() * scaleY),
+								POINT_SIZE, paint);
+					}
+				}
+			}
+			if (currentLast != null) {
+				paint.setAlpha(CURRENT_POINT_OPACITY / 2);
+				paint.setColor(resultPointColor);
+				synchronized (currentLast) {
+					float radius = POINT_SIZE / 2.0f;
+					for (ResultPoint point : currentLast) {
+						canvas.drawCircle(
+								frameLeft + (int) (point.getX() * scaleX),
+								frameTop + (int) (point.getY() * scaleY),
+								radius, paint);
+					}
+				}
+			}
+
+			// Request another update at the animation interval, but only
+			// repaint the laser line, not the entire viewfinder mask.
+			postInvalidateDelayed(ANIMATION_DELAY,
+					frame.left - POINT_SIZE,
+					frame.top - POINT_SIZE,
+					frame.right + POINT_SIZE,
+					frame.bottom + POINT_SIZE);
+		}
+	}
+
+	public void drawViewfinder() {
+		Bitmap resultBitmap = this.resultBitmap;
+		this.resultBitmap = null;
+		if (resultBitmap != null) {
+			resultBitmap.recycle();
+		}
+		invalidate();
+	}
+
+	/**
+	 * Draw a bitmap with the result points highlighted instead of the live
+	 * scanning display.
+	 *
+	 * @param barcode An image of the decoded barcode.
+	 */
+	public void drawResultBitmap(Bitmap barcode) {
+		resultBitmap = barcode;
+		invalidate();
+	}
+
+	public void addPossibleResultPoint(ResultPoint point) {
+		List<ResultPoint> points = possibleResultPoints;
+		synchronized (points) {
+			points.add(point);
+			int size = points.size();
+			if (size > MAX_RESULT_POINTS) {
+				// trim it
+				points.subList(0, size - MAX_RESULT_POINTS / 2).clear();
+			}
+		}
+	}
+
+	public interface FrameProvider {
+
+		Rect getFramingRect();
+		Rect getFramingRectInPreview();
+	}
+}

briar-api/build.gradle

@@ -4,10 +4,6 @@ targetCompatibility = 1.6
 
 apply plugin: 'witness'
 
-repositories {
-	jcenter()
-}
-
 dependencies {
 	compile "com.google.dagger:dagger:2.0.2"
 	compile 'com.google.dagger:dagger-compiler:2.0.2'

briar-api/src/org/briarproject/api/clients/BdfMessageContext.java

@@ -0,0 +1,28 @@
+package org.briarproject.api.clients;
+
+import org.briarproject.api.data.BdfDictionary;
+import org.briarproject.api.sync.BaseMessageContext;
+import org.briarproject.api.sync.MessageId;
+
+import java.util.Collection;
+
+public class BdfMessageContext extends BaseMessageContext {
+
+	private final BdfDictionary dictionary;
+
+	public BdfMessageContext(BdfDictionary dictionary,
+			Collection<MessageId> dependencies) {
+
+		super(dependencies);
+		this.dictionary = dictionary;
+	}
+
+	public BdfMessageContext(BdfDictionary dictionary) {
+		this(dictionary, null);
+	}
+
+	public BdfDictionary getDictionary() {
+		return dictionary;
+	}
+
+}

briar-api/src/org/briarproject/api/clients/MessageQueueManager.java

@@ -5,6 +5,8 @@ import org.briarproject.api.db.Metadata;
 import org.briarproject.api.db.Transaction;
 import org.briarproject.api.sync.ClientId;
 import org.briarproject.api.sync.Group;
+import org.briarproject.api.sync.InvalidMessageException;
+import org.briarproject.api.sync.MessageContext;
 
 public interface MessageQueueManager {
 
@@ -34,10 +36,11 @@ public interface MessageQueueManager {
 	interface QueueMessageValidator {
 
 		/**
-		 * Validates the given message and returns its metadata if the message
-		 * is valid, or null if the message is invalid.
+		 * Validates the given message and returns its metadata and
+		 * dependencies.
 		 */
-		Metadata validateMessage(QueueMessage q, Group g);
+		MessageContext validateMessage(QueueMessage q, Group g)
+				throws InvalidMessageException;
 	}
 
 	interface IncomingQueueMessageHook {

briar-api/src/org/briarproject/api/forum/ForumFactory.java

@@ -0,0 +1,11 @@
+package org.briarproject.api.forum;
+
+public interface ForumFactory {
+
+	/** Creates a forum with the given name. */
+	Forum createForum(String name);
+
+	/** Creates a forum with the given name and salt. */
+	Forum createForum(String name, byte[] salt);
+
+}

briar-api/src/org/briarproject/api/forum/ForumManager.java

@@ -13,14 +13,8 @@ public interface ForumManager {
 	/** Returns the unique ID of the forum client. */
 	ClientId getClientId();
 
-	/** Creates a forum with the given name. */
-	Forum createForum(String name);
-
-	/** Creates a forum with the given name and salt. */
-	Forum createForum(String name, byte[] salt);
-
 	/** Subscribes to a forum. */
-	void addForum(Forum f) throws DbException;
+	Forum addForum(String name) throws DbException;
 
 	/** Unsubscribes from a forum. */
 	void removeForum(Forum f) throws DbException;

briar-api/src/org/briarproject/api/forum/ForumSharingManager.java

@@ -24,7 +24,8 @@ public interface ForumSharingManager {
 	/**
 	 * Responds to a pending forum invitation
 	 */
-	void respondToInvitation(Forum f, boolean accept) throws DbException;
+	void respondToInvitation(Forum f, Contact c, boolean accept)
+			throws DbException;
 
 	/**
 	 * Returns all forum sharing messages sent by the Contact
@@ -40,7 +41,7 @@ public interface ForumSharingManager {
 	Collection<Contact> getSharedBy(GroupId g) throws DbException;
 
 	/** Returns the IDs of all contacts with whom the given forum is shared. */
-	Collection<ContactId> getSharedWith(GroupId g) throws DbException;
+	Collection<Contact> getSharedWith(GroupId g) throws DbException;
 
 	/** Returns true if the forum not already shared and no invitation is open */
 	boolean canBeShared(GroupId g, Contact c) throws DbException;

briar-api/src/org/briarproject/api/forum/ForumSharingMessage.java

@@ -0,0 +1,166 @@
+package org.briarproject.api.forum;
+
+import org.briarproject.api.FormatException;
+import org.briarproject.api.clients.SessionId;
+import org.briarproject.api.data.BdfDictionary;
+import org.briarproject.api.data.BdfEntry;
+import org.briarproject.api.data.BdfList;
+import org.briarproject.api.sync.GroupId;
+
+import static org.briarproject.api.forum.ForumConstants.FORUM_NAME;
+import static org.briarproject.api.forum.ForumConstants.FORUM_SALT;
+import static org.briarproject.api.forum.ForumConstants.GROUP_ID;
+import static org.briarproject.api.forum.ForumConstants.INVITATION_MSG;
+import static org.briarproject.api.forum.ForumConstants.SESSION_ID;
+import static org.briarproject.api.forum.ForumConstants.SHARE_MSG_TYPE_ABORT;
+import static org.briarproject.api.forum.ForumConstants.SHARE_MSG_TYPE_ACCEPT;
+import static org.briarproject.api.forum.ForumConstants.SHARE_MSG_TYPE_DECLINE;
+import static org.briarproject.api.forum.ForumConstants.SHARE_MSG_TYPE_INVITATION;
+import static org.briarproject.api.forum.ForumConstants.SHARE_MSG_TYPE_LEAVE;
+import static org.briarproject.api.forum.ForumConstants.TYPE;
+
+public interface ForumSharingMessage {
+
+	abstract class BaseMessage {
+		private final GroupId groupId;
+		private final SessionId sessionId;
+
+		public BaseMessage(GroupId groupId, SessionId sessionId) {
+
+			this.groupId = groupId;
+			this.sessionId = sessionId;
+		}
+
+		public BdfList toBdfList() {
+			return BdfList.of(getType(), getSessionId());
+		}
+
+		public abstract BdfDictionary toBdfDictionary();
+
+		protected BdfDictionary toBdfDictionaryHelper() {
+			return BdfDictionary.of(
+					new BdfEntry(TYPE, getType()),
+					new BdfEntry(GROUP_ID, groupId),
+					new BdfEntry(SESSION_ID, sessionId)
+			);
+		}
+
+		public static BaseMessage from(GroupId groupId, BdfDictionary d)
+				throws FormatException {
+
+			long type = d.getLong(TYPE);
+
+			if (type == SHARE_MSG_TYPE_INVITATION)
+				return Invitation.from(groupId, d);
+			else
+				return SimpleMessage.from(type, groupId, d);
+		}
+
+		public abstract long getType();
+
+		public GroupId getGroupId() {
+			return groupId;
+		}
+
+		public SessionId getSessionId() {
+			return sessionId;
+		}
+	}
+
+	class Invitation extends BaseMessage {
+
+		private final String forumName;
+		private final byte[] forumSalt;
+		private final String message;
+
+		public Invitation(GroupId groupId, SessionId sessionId,
+				String forumName, byte[] forumSalt, String message) {
+
+			super(groupId, sessionId);
+
+			this.forumName = forumName;
+			this.forumSalt = forumSalt;
+			this.message = message;
+		}
+
+		@Override
+		public long getType() {
+			return SHARE_MSG_TYPE_INVITATION;
+		}
+
+		@Override
+		public BdfList toBdfList() {
+			BdfList list = super.toBdfList();
+			list.add(forumName);
+			list.add(forumSalt);
+			if (message != null) list.add(message);
+			return list;
+		}
+
+		@Override
+		public BdfDictionary toBdfDictionary() {
+			BdfDictionary d = toBdfDictionaryHelper();
+			d.put(FORUM_NAME, forumName);
+			d.put(FORUM_SALT, forumSalt);
+			if (message != null) d.put(INVITATION_MSG, message);
+			return d;
+		}
+
+		public static Invitation from(GroupId groupId, BdfDictionary d)
+				throws FormatException {
+
+			SessionId sessionId = new SessionId(d.getRaw(SESSION_ID));
+			String forumName = d.getString(FORUM_NAME);
+			byte[] forumSalt = d.getRaw(FORUM_SALT);
+			String message = d.getOptionalString(INVITATION_MSG);
+
+			return new Invitation(groupId, sessionId, forumName, forumSalt,
+					message);
+		}
+
+		public String getForumName() {
+			return forumName;
+		}
+
+		public byte[] getForumSalt() {
+			return forumSalt;
+		}
+
+		public String getMessage() {
+			return message;
+		}
+	}
+
+	class SimpleMessage extends BaseMessage {
+
+		private final long type;
+
+		public SimpleMessage(long type, GroupId groupId, SessionId sessionId) {
+			super(groupId, sessionId);
+			this.type = type;
+		}
+
+		@Override
+		public long getType() {
+			return type;
+		}
+
+		@Override
+		public BdfDictionary toBdfDictionary() {
+			return toBdfDictionaryHelper();
+		}
+
+		public static SimpleMessage from(long type, GroupId groupId,
+				BdfDictionary d) throws FormatException {
+
+			if (type != SHARE_MSG_TYPE_ACCEPT &&
+					type != SHARE_MSG_TYPE_DECLINE &&
+					type != SHARE_MSG_TYPE_LEAVE &&
+					type != SHARE_MSG_TYPE_ABORT) throw new FormatException();
+
+			SessionId sessionId = new SessionId(d.getRaw(SESSION_ID));
+			return new SimpleMessage(type, groupId, sessionId);
+		}
+	}
+
+}

briar-api/src/org/briarproject/api/forum/InviteeAction.java

@@ -1,34 +0,0 @@
-package org.briarproject.api.forum;
-
-import static org.briarproject.api.forum.ForumConstants.SHARE_MSG_TYPE_ABORT;
-import static org.briarproject.api.forum.ForumConstants.SHARE_MSG_TYPE_ACCEPT;
-import static org.briarproject.api.forum.ForumConstants.SHARE_MSG_TYPE_DECLINE;
-import static org.briarproject.api.forum.ForumConstants.SHARE_MSG_TYPE_INVITATION;
-import static org.briarproject.api.forum.ForumConstants.SHARE_MSG_TYPE_LEAVE;
-
-public enum InviteeAction {
-
-	LOCAL_ACCEPT,
-	LOCAL_DECLINE,
-	LOCAL_LEAVE,
-	LOCAL_ABORT,
-	REMOTE_INVITATION,
-	REMOTE_LEAVE,
-	REMOTE_ABORT;
-
-	public static InviteeAction getLocal(long type) {
-		if (type == SHARE_MSG_TYPE_ACCEPT) return LOCAL_ACCEPT;
-		if (type == SHARE_MSG_TYPE_DECLINE) return LOCAL_DECLINE;
-		if (type == SHARE_MSG_TYPE_LEAVE) return LOCAL_LEAVE;
-		if (type == SHARE_MSG_TYPE_ABORT) return LOCAL_ABORT;
-		return null;
-	}
-
-	public static InviteeAction getRemote(long type) {
-		if (type == SHARE_MSG_TYPE_INVITATION) return REMOTE_INVITATION;
-		if (type == SHARE_MSG_TYPE_LEAVE) return REMOTE_LEAVE;
-		if (type == SHARE_MSG_TYPE_ABORT) return REMOTE_ABORT;
-		return null;
-	}
-
-}

briar-api/src/org/briarproject/api/forum/InviteeProtocolState.java

@@ -1,62 +0,0 @@
-package org.briarproject.api.forum;
-
-import static org.briarproject.api.forum.InviteeAction.LOCAL_ACCEPT;
-import static org.briarproject.api.forum.InviteeAction.LOCAL_DECLINE;
-import static org.briarproject.api.forum.InviteeAction.LOCAL_LEAVE;
-import static org.briarproject.api.forum.InviteeAction.REMOTE_INVITATION;
-import static org.briarproject.api.forum.InviteeAction.REMOTE_LEAVE;
-
-public enum InviteeProtocolState {
-
-	ERROR(0),
-	AWAIT_INVITATION(1) {
-		@Override
-		public InviteeProtocolState next(InviteeAction a) {
-			if (a == REMOTE_INVITATION) return AWAIT_LOCAL_RESPONSE;
-			return ERROR;
-		}
-	},
-	AWAIT_LOCAL_RESPONSE(2) {
-		@Override
-		public InviteeProtocolState next(InviteeAction a) {
-			if (a == LOCAL_ACCEPT || a == LOCAL_DECLINE) return FINISHED;
-			if (a == REMOTE_LEAVE) return LEFT;
-			return ERROR;
-		}
-	},
-	FINISHED(3) {
-		@Override
-		public InviteeProtocolState next(InviteeAction a) {
-			if (a == LOCAL_LEAVE || a == REMOTE_LEAVE) return LEFT;
-			return FINISHED;
-		}
-	},
-	LEFT(4) {
-		@Override
-		public InviteeProtocolState next(InviteeAction a) {
-			if (a == LOCAL_LEAVE) return ERROR;
-			return LEFT;
-		}
-	};
-
-	private final int value;
-
-	InviteeProtocolState(int value) {
-		this.value = value;
-	}
-
-	public int getValue() {
-		return value;
-	}
-
-	public static InviteeProtocolState fromValue(int value) {
-		for (InviteeProtocolState s : values()) {
-			if (s.value == value) return s;
-		}
-		throw new IllegalArgumentException();
-	}
-
-	public InviteeProtocolState next(InviteeAction a) {
-		return this;
-	}
-}

briar-api/src/org/briarproject/api/forum/SharerAction.java

@@ -1,34 +0,0 @@
-package org.briarproject.api.forum;
-
-import static org.briarproject.api.forum.ForumConstants.SHARE_MSG_TYPE_ABORT;
-import static org.briarproject.api.forum.ForumConstants.SHARE_MSG_TYPE_ACCEPT;
-import static org.briarproject.api.forum.ForumConstants.SHARE_MSG_TYPE_DECLINE;
-import static org.briarproject.api.forum.ForumConstants.SHARE_MSG_TYPE_INVITATION;
-import static org.briarproject.api.forum.ForumConstants.SHARE_MSG_TYPE_LEAVE;
-
-public enum SharerAction {
-
-	LOCAL_INVITATION,
-	LOCAL_LEAVE,
-	LOCAL_ABORT,
-	REMOTE_ACCEPT,
-	REMOTE_DECLINE,
-	REMOTE_LEAVE,
-	REMOTE_ABORT;
-
-	public static SharerAction getLocal(long type) {
-		if (type == SHARE_MSG_TYPE_INVITATION) return LOCAL_INVITATION;
-		if (type == SHARE_MSG_TYPE_LEAVE) return LOCAL_LEAVE;
-		if (type == SHARE_MSG_TYPE_ABORT) return LOCAL_ABORT;
-		return null;
-	}
-
-	public static SharerAction getRemote(long type) {
-		if (type == SHARE_MSG_TYPE_ACCEPT) return REMOTE_ACCEPT;
-		if (type == SHARE_MSG_TYPE_DECLINE) return REMOTE_DECLINE;
-		if (type == SHARE_MSG_TYPE_LEAVE) return REMOTE_LEAVE;
-		if (type == SHARE_MSG_TYPE_ABORT) return REMOTE_ABORT;
-		return null;
-	}
-
-}

briar-api/src/org/briarproject/api/forum/SharerProtocolState.java

@@ -1,62 +0,0 @@
-package org.briarproject.api.forum;
-
-import static org.briarproject.api.forum.SharerAction.LOCAL_INVITATION;
-import static org.briarproject.api.forum.SharerAction.LOCAL_LEAVE;
-import static org.briarproject.api.forum.SharerAction.REMOTE_ACCEPT;
-import static org.briarproject.api.forum.SharerAction.REMOTE_DECLINE;
-import static org.briarproject.api.forum.SharerAction.REMOTE_LEAVE;
-
-public enum SharerProtocolState {
-
-	ERROR(0),
-	PREPARE_INVITATION(1) {
-		@Override
-		public SharerProtocolState next(SharerAction a) {
-			if (a == LOCAL_INVITATION) return AWAIT_RESPONSE;
-			return ERROR;
-		}
-	},
-	AWAIT_RESPONSE(2) {
-		@Override
-		public SharerProtocolState next(SharerAction a) {
-			if (a == REMOTE_ACCEPT || a == REMOTE_DECLINE) return FINISHED;
-			if (a == LOCAL_LEAVE) return LEFT;
-			return ERROR;
-		}
-	},
-	FINISHED(3) {
-		@Override
-		public SharerProtocolState next(SharerAction a) {
-			if (a == LOCAL_LEAVE || a == REMOTE_LEAVE) return LEFT;
-			return FINISHED;
-		}
-	},
-	LEFT(4) {
-		@Override
-		public SharerProtocolState next(SharerAction a) {
-			if (a == LOCAL_LEAVE) return ERROR;
-			return LEFT;
-		}
-	};
-
-	private final int value;
-
-	SharerProtocolState(int value) {
-		this.value = value;
-	}
-
-	public int getValue() {
-		return value;
-	}
-
-	public static SharerProtocolState fromValue(int value) {
-		for (SharerProtocolState s : values()) {
-			if (s.value == value) return s;
-		}
-		throw new IllegalArgumentException();
-	}
-
-	public SharerProtocolState next(SharerAction a) {
-		return this;
-	}
-}

briar-api/src/org/briarproject/api/sync/BaseMessageContext.java

@@ -0,0 +1,17 @@
+package org.briarproject.api.sync;
+
+import java.util.Collection;
+
+public abstract class BaseMessageContext {
+
+	private final Collection<MessageId> dependencies;
+
+	public BaseMessageContext(Collection<MessageId> dependencies) {
+		this.dependencies = dependencies;
+	}
+
+	public Collection<MessageId> getDependencies() {
+		return dependencies;
+	}
+
+}

briar-api/src/org/briarproject/api/sync/InvalidMessageException.java

@@ -0,0 +1,20 @@
+package org.briarproject.api.sync;
+
+import java.io.IOException;
+
+/** An exception that indicates an invalid message. */
+public class InvalidMessageException extends IOException {
+
+	public InvalidMessageException() {
+		super();
+	}
+
+	public InvalidMessageException(String str) {
+		super(str);
+	}
+
+	public InvalidMessageException(Throwable t) {
+		super(t);
+	}
+
+}

briar-api/src/org/briarproject/api/sync/MessageContext.java

@@ -0,0 +1,26 @@
+package org.briarproject.api.sync;
+
+import org.briarproject.api.db.Metadata;
+
+import java.util.Collection;
+
+public class MessageContext extends BaseMessageContext {
+
+	private final Metadata metadata;
+
+	public MessageContext(Metadata metadata,
+			Collection<MessageId> dependencies) {
+
+		super(dependencies);
+		this.metadata = metadata;
+	}
+
+	public MessageContext(Metadata metadata) {
+		this(metadata, null);
+	}
+
+	public Metadata getMetadata() {
+		return metadata;
+	}
+
+}

briar-api/src/org/briarproject/api/sync/ValidationManager.java

@@ -44,10 +44,11 @@ public interface ValidationManager {
 	interface MessageValidator {
 
 		/**
-		 * Validates the given message and returns its metadata if the message
-		 * is valid, or null if the message is invalid.
+		 * Validates the given message and returns its metadata and
+		 * dependencies.
 		 */
-		Metadata validateMessage(Message m, Group g);
+		MessageContext validateMessage(Message m, Group g)
+				throws InvalidMessageException;
 	}
 
 	interface IncomingMessageHook {

briar-core/build.gradle

@@ -4,10 +4,6 @@ targetCompatibility = 1.6
 
 apply plugin: 'witness'
 
-repositories {
-	jcenter()
-}
-
 dependencies {
 	compile project(':briar-api')
 	compile fileTree(dir: 'libs', include: '*.jar')

briar-core/src/org/briarproject/clients/BdfMessageValidator.java

@@ -4,13 +4,16 @@ import org.briarproject.api.FormatException;
 import org.briarproject.api.clients.ClientHelper;
 import org.briarproject.api.clients.MessageQueueManager.QueueMessageValidator;
 import org.briarproject.api.clients.QueueMessage;
+import org.briarproject.api.clients.BdfMessageContext;
 import org.briarproject.api.data.BdfDictionary;
 import org.briarproject.api.data.BdfList;
 import org.briarproject.api.data.MetadataEncoder;
 import org.briarproject.api.db.Metadata;
 import org.briarproject.api.sync.Group;
+import org.briarproject.api.sync.InvalidMessageException;
 import org.briarproject.api.sync.Message;
 import org.briarproject.api.sync.ValidationManager.MessageValidator;
+import org.briarproject.api.sync.MessageContext;
 import org.briarproject.api.system.Clock;
 import org.briarproject.util.StringUtils;
 
@@ -37,43 +40,41 @@ public abstract class BdfMessageValidator implements MessageValidator,
 		this.clock = clock;
 	}
 
-	protected abstract BdfDictionary validateMessage(Message m, Group g,
-			BdfList body) throws FormatException;
+	protected abstract BdfMessageContext validateMessage(Message m, Group g,
+			BdfList body) throws InvalidMessageException, FormatException;
 
 	@Override
-	public Metadata validateMessage(Message m, Group g) {
+	public MessageContext validateMessage(Message m, Group g)
+			throws InvalidMessageException {
 		return validateMessage(m, g, MESSAGE_HEADER_LENGTH);
 	}
 
 	@Override
-	public Metadata validateMessage(QueueMessage q, Group g) {
+	public MessageContext validateMessage(QueueMessage q, Group g)
+			throws InvalidMessageException {
 		return validateMessage(q, g, QUEUE_MESSAGE_HEADER_LENGTH);
 	}
 
-	private Metadata validateMessage(Message m, Group g, int headerLength) {
+	private MessageContext validateMessage(Message m, Group g, int headerLength)
+			throws InvalidMessageException {
 		// Reject the message if it's too far in the future
 		long now = clock.currentTimeMillis();
 		if (m.getTimestamp() - now > MAX_CLOCK_DIFFERENCE) {
-			LOG.info("Timestamp is too far in the future");
-			return null;
+			throw new InvalidMessageException(
+					"Timestamp is too far in the future");
 		}
 		byte[] raw = m.getRaw();
 		if (raw.length <= headerLength) {
-			LOG.info("Message is too short");
-			return null;
+			throw new InvalidMessageException("Message is too short");
 		}
 		try {
 			BdfList body = clientHelper.toList(raw, headerLength,
 					raw.length - headerLength);
-			BdfDictionary meta = validateMessage(m, g, body);
-			if (meta == null) {
-				LOG.info("Invalid message");
-				return null;
-			}
-			return metadataEncoder.encode(meta);
+			BdfMessageContext result = validateMessage(m, g, body);
+			Metadata meta = metadataEncoder.encode(result.getDictionary());
+			return new MessageContext(meta, result.getDependencies());
 		} catch (FormatException e) {
-			LOG.info("Invalid message");
-			return null;
+			throw new InvalidMessageException(e);
 		}
 	}
 

briar-core/src/org/briarproject/clients/MessageQueueManagerImpl.java

@@ -14,10 +14,12 @@ import org.briarproject.api.db.Transaction;
 import org.briarproject.api.sync.ClientId;
 import org.briarproject.api.sync.Group;
 import org.briarproject.api.sync.GroupId;
+import org.briarproject.api.sync.InvalidMessageException;
 import org.briarproject.api.sync.Message;
 import org.briarproject.api.sync.MessageId;
 import org.briarproject.api.sync.ValidationManager;
 import org.briarproject.api.sync.ValidationManager.IncomingMessageHook;
+import org.briarproject.api.sync.MessageContext;
 import org.briarproject.util.ByteUtils;
 
 import java.util.ArrayList;
@@ -169,7 +171,8 @@ class MessageQueueManagerImpl implements MessageQueueManager {
 		}
 
 		@Override
-		public Metadata validateMessage(Message m, Group g) {
+		public MessageContext validateMessage(Message m, Group g)
+				throws InvalidMessageException {
 			byte[] raw = m.getRaw();
 			if (raw.length < QUEUE_MESSAGE_HEADER_LENGTH) return null;
 			long queuePosition = ByteUtils.readUint64(raw,

briar-core/src/org/briarproject/forum/ForumFactoryImpl.java

@@ -0,0 +1,58 @@
+package org.briarproject.forum;
+
+import org.briarproject.api.FormatException;
+import org.briarproject.api.clients.ClientHelper;
+import org.briarproject.api.data.BdfList;
+import org.briarproject.api.forum.Forum;
+import org.briarproject.api.forum.ForumFactory;
+import org.briarproject.api.sync.Group;
+import org.briarproject.api.sync.GroupFactory;
+import org.briarproject.util.StringUtils;
+
+import java.security.SecureRandom;
+
+import javax.inject.Inject;
+
+import static org.briarproject.api.forum.ForumConstants.FORUM_SALT_LENGTH;
+import static org.briarproject.api.forum.ForumConstants.MAX_FORUM_NAME_LENGTH;
+
+class ForumFactoryImpl implements ForumFactory {
+
+	private final GroupFactory groupFactory;
+	private final ClientHelper clientHelper;
+	private final SecureRandom random;
+
+	@Inject
+	ForumFactoryImpl(GroupFactory groupFactory, ClientHelper clientHelper,
+			SecureRandom random) {
+
+		this.groupFactory = groupFactory;
+		this.clientHelper = clientHelper;
+		this.random = random;
+	}
+
+	@Override
+	public Forum createForum(String name) {
+		int length = StringUtils.toUtf8(name).length;
+		if (length == 0) throw new IllegalArgumentException();
+		if (length > MAX_FORUM_NAME_LENGTH)
+			throw new IllegalArgumentException();
+		byte[] salt = new byte[FORUM_SALT_LENGTH];
+		random.nextBytes(salt);
+		return createForum(name, salt);
+	}
+
+	@Override
+	public Forum createForum(String name, byte[] salt) {
+		try {
+			BdfList forum = BdfList.of(name, salt);
+			byte[] descriptor = clientHelper.toByteArray(forum);
+			Group g = groupFactory
+					.createGroup(ForumManagerImpl.CLIENT_ID, descriptor);
+			return new Forum(g, name, salt);
+		} catch (FormatException e) {
+			throw new RuntimeException(e);
+		}
+	}
+
+}

briar-core/src/org/briarproject/forum/ForumManagerImpl.java

@@ -9,6 +9,7 @@ import org.briarproject.api.db.DatabaseComponent;
 import org.briarproject.api.db.DbException;
 import org.briarproject.api.db.Transaction;
 import org.briarproject.api.forum.Forum;
+import org.briarproject.api.forum.ForumFactory;
 import org.briarproject.api.forum.ForumManager;
 import org.briarproject.api.forum.ForumPost;
 import org.briarproject.api.forum.ForumPostHeader;
@@ -17,12 +18,10 @@ import org.briarproject.api.identity.AuthorId;
 import org.briarproject.api.identity.LocalAuthor;
 import org.briarproject.api.sync.ClientId;
 import org.briarproject.api.sync.Group;
-import org.briarproject.api.sync.GroupFactory;
 import org.briarproject.api.sync.GroupId;
 import org.briarproject.api.sync.MessageId;
 import org.briarproject.util.StringUtils;
 
-import java.security.SecureRandom;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
@@ -35,8 +34,6 @@ import java.util.concurrent.CopyOnWriteArrayList;
 
 import javax.inject.Inject;
 
-import static org.briarproject.api.forum.ForumConstants.FORUM_SALT_LENGTH;
-import static org.briarproject.api.forum.ForumConstants.MAX_FORUM_NAME_LENGTH;
 import static org.briarproject.api.identity.Author.Status.ANONYMOUS;
 import static org.briarproject.api.identity.Author.Status.UNKNOWN;
 import static org.briarproject.api.identity.Author.Status.VERIFIED;
@@ -49,18 +46,16 @@ class ForumManagerImpl implements ForumManager {
 
 	private final DatabaseComponent db;
 	private final ClientHelper clientHelper;
-	private final GroupFactory groupFactory;
-	private final SecureRandom random;
+	private final ForumFactory forumFactory;
 	private final List<RemoveForumHook> removeHooks;
 
 	@Inject
 	ForumManagerImpl(DatabaseComponent db, ClientHelper clientHelper,
-			GroupFactory groupFactory, SecureRandom random) {
+			ForumFactory forumFactory) {
 
 		this.db = db;
 		this.clientHelper = clientHelper;
-		this.groupFactory = groupFactory;
-		this.random = random;
+		this.forumFactory = forumFactory;
 		removeHooks = new CopyOnWriteArrayList<RemoveForumHook>();
 	}
 
@@ -70,30 +65,9 @@ class ForumManagerImpl implements ForumManager {
 	}
 
 	@Override
-	public Forum createForum(String name) {
-		int length = StringUtils.toUtf8(name).length;
-		if (length == 0) throw new IllegalArgumentException();
-		if (length > MAX_FORUM_NAME_LENGTH)
-			throw new IllegalArgumentException();
-		byte[] salt = new byte[FORUM_SALT_LENGTH];
-		random.nextBytes(salt);
-		return createForum(name, salt);
-	}
+	public Forum addForum(String name) throws DbException {
+		Forum f = forumFactory.createForum(name);
 
-	@Override
-	public Forum createForum(String name, byte[] salt) {
-		try {
-			BdfList forum = BdfList.of(name, salt);
-			byte[] descriptor = clientHelper.toByteArray(forum);
-			Group g = groupFactory.createGroup(getClientId(), descriptor);
-			return new Forum(g, name, salt);
-		} catch (FormatException e) {
-			throw new RuntimeException(e);
-		}
-	}
-
-	@Override
-	public void addForum(Forum f) throws DbException {
 		Transaction txn = db.startTransaction(false);
 		try {
 			db.addGroup(txn, f.getGroup());
@@ -101,6 +75,7 @@ class ForumManagerImpl implements ForumManager {
 		} finally {
 			db.endTransaction(txn);
 		}
+		return f;
 	}
 
 	@Override

briar-core/src/org/briarproject/forum/ForumModule.java

@@ -6,6 +6,7 @@ import org.briarproject.api.contact.ContactManager;
 import org.briarproject.api.crypto.CryptoComponent;
 import org.briarproject.api.data.MetadataEncoder;
 import org.briarproject.api.db.DatabaseComponent;
+import org.briarproject.api.forum.ForumFactory;
 import org.briarproject.api.forum.ForumManager;
 import org.briarproject.api.forum.ForumPostFactory;
 import org.briarproject.api.forum.ForumSharingManager;
@@ -38,9 +39,8 @@ public class ForumModule {
 	@Provides
 	@Singleton
 	ForumManager provideForumManager(DatabaseComponent db,
-			ClientHelper clientHelper,
-			GroupFactory groupFactory, SecureRandom random) {
-		return new ForumManagerImpl(db, clientHelper, groupFactory, random);
+			ClientHelper clientHelper, ForumFactory forumFactory) {
+		return new ForumManagerImpl(db, clientHelper, forumFactory);
 	}
 
 	@Provides
@@ -49,6 +49,12 @@ public class ForumModule {
 		return new ForumPostFactoryImpl(crypto, clientHelper);
 	}
 
+	@Provides
+	ForumFactory provideForumFactory(GroupFactory groupFactory,
+			ClientHelper clientHelper, SecureRandom random) {
+		return new ForumFactoryImpl(groupFactory, clientHelper, random);
+	}
+
 	@Provides
 	@Singleton
 	ForumPostValidator provideForumPostValidator(
@@ -82,7 +88,7 @@ public class ForumModule {
 			LifecycleManager lifecycleManager,
 			ContactManager contactManager,
 			MessageQueueManager messageQueueManager,
-			ForumManager forumManager,
+			ForumManager forumManager, ForumFactory forumFactory,
 			ForumSharingManagerImpl forumSharingManager) {
 
 		lifecycleManager.registerClient(forumSharingManager);

briar-core/src/org/briarproject/forum/ForumPostValidator.java

@@ -3,6 +3,7 @@ package org.briarproject.forum;
 import org.briarproject.api.FormatException;
 import org.briarproject.api.UniqueId;
 import org.briarproject.api.clients.ClientHelper;
+import org.briarproject.api.clients.BdfMessageContext;
 import org.briarproject.api.crypto.CryptoComponent;
 import org.briarproject.api.crypto.KeyParser;
 import org.briarproject.api.crypto.PublicKey;
@@ -13,6 +14,7 @@ import org.briarproject.api.data.MetadataEncoder;
 import org.briarproject.api.identity.Author;
 import org.briarproject.api.identity.AuthorFactory;
 import org.briarproject.api.sync.Group;
+import org.briarproject.api.sync.InvalidMessageException;
 import org.briarproject.api.sync.Message;
 import org.briarproject.api.system.Clock;
 import org.briarproject.clients.BdfMessageValidator;
@@ -39,8 +41,8 @@ class ForumPostValidator extends BdfMessageValidator {
 	}
 
 	@Override
-	protected BdfDictionary validateMessage(Message m, Group g,
-			BdfList body) throws FormatException {
+	protected BdfMessageContext validateMessage(Message m, Group g,
+			BdfList body) throws InvalidMessageException, FormatException {
 		// Parent ID, author, content type, forum post body, signature
 		checkSize(body, 5);
 		// Parent ID is optional
@@ -69,12 +71,10 @@ class ForumPostValidator extends BdfMessageValidator {
 		checkLength(sig, 0, MAX_SIGNATURE_LENGTH);
 		// If there's an author there must be a signature and vice versa
 		if (author != null && sig == null) {
-			LOG.info("Author without signature");
-			return null;
+			throw new InvalidMessageException("Author without signature");
 		}
 		if (author == null && sig != null) {
-			LOG.info("Signature without author");
-			return null;
+			throw new InvalidMessageException("Signature without author");
 		}
 		// Verify the signature, if any
 		if (author != null) {
@@ -90,12 +90,10 @@ class ForumPostValidator extends BdfMessageValidator {
 				signature.initVerify(key);
 				signature.update(clientHelper.toByteArray(signed));
 				if (!signature.verify(sig)) {
-					LOG.info("Invalid signature");
-					return null;
+					throw new InvalidMessageException("Invalid signature");
 				}
 			} catch (GeneralSecurityException e) {
-				LOG.info("Invalid public key");
-				return null;
+				throw new InvalidMessageException("Invalid public key");
 			}
 		}
 		// Return the metadata
@@ -111,6 +109,6 @@ class ForumPostValidator extends BdfMessageValidator {
 		}
 		meta.put("contentType", contentType);
 		meta.put("read", false);
-		return meta;
+		return new BdfMessageContext(meta);
 	}
 }

briar-core/src/org/briarproject/forum/ForumSharingManagerImpl.java

@@ -23,13 +23,10 @@ import org.briarproject.api.db.NoSuchMessageException;
 import org.briarproject.api.db.Transaction;
 import org.briarproject.api.event.Event;
 import org.briarproject.api.forum.Forum;
+import org.briarproject.api.forum.ForumFactory;
 import org.briarproject.api.forum.ForumInvitationMessage;
 import org.briarproject.api.forum.ForumManager;
 import org.briarproject.api.forum.ForumSharingManager;
-import org.briarproject.api.forum.InviteeAction;
-import org.briarproject.api.forum.InviteeProtocolState;
-import org.briarproject.api.forum.SharerAction;
-import org.briarproject.api.forum.SharerProtocolState;
 import org.briarproject.api.sync.ClientId;
 import org.briarproject.api.sync.Group;
 import org.briarproject.api.sync.GroupId;
@@ -59,11 +56,7 @@ import static java.util.logging.Level.WARNING;
 import static org.briarproject.api.clients.ProtocolEngine.StateUpdate;
 import static org.briarproject.api.forum.ForumConstants.CONTACT_ID;
 import static org.briarproject.api.forum.ForumConstants.FORUM_ID;
-import static org.briarproject.api.forum.ForumConstants.FORUM_NAME;
-import static org.briarproject.api.forum.ForumConstants.FORUM_SALT;
 import static org.briarproject.api.forum.ForumConstants.FORUM_SALT_LENGTH;
-import static org.briarproject.api.forum.ForumConstants.GROUP_ID;
-import static org.briarproject.api.forum.ForumConstants.INVITATION_MSG;
 import static org.briarproject.api.forum.ForumConstants.IS_SHARER;
 import static org.briarproject.api.forum.ForumConstants.LOCAL;
 import static org.briarproject.api.forum.ForumConstants.READ;
@@ -76,10 +69,8 @@ import static org.briarproject.api.forum.ForumConstants.SHARE_MSG_TYPE_DECLINE;
 import static org.briarproject.api.forum.ForumConstants.SHARE_MSG_TYPE_INVITATION;
 import static org.briarproject.api.forum.ForumConstants.SHARE_MSG_TYPE_LEAVE;
 import static org.briarproject.api.forum.ForumConstants.STATE;
-import static org.briarproject.api.forum.ForumConstants.STORAGE_ID;
-import static org.briarproject.api.forum.ForumConstants.TASK;
-import static org.briarproject.api.forum.ForumConstants.TASK_ADD_FORUM_TO_LIST_TO_BE_SHARED_BY_US;
 import static org.briarproject.api.forum.ForumConstants.TASK_ADD_FORUM_TO_LIST_SHARED_WITH_US;
+import static org.briarproject.api.forum.ForumConstants.TASK_ADD_FORUM_TO_LIST_TO_BE_SHARED_BY_US;
 import static org.briarproject.api.forum.ForumConstants.TASK_ADD_SHARED_FORUM;
 import static org.briarproject.api.forum.ForumConstants.TASK_REMOVE_FORUM_FROM_LIST_SHARED_WITH_US;
 import static org.briarproject.api.forum.ForumConstants.TASK_REMOVE_FORUM_FROM_LIST_TO_BE_SHARED_BY_US;
@@ -90,9 +81,10 @@ import static org.briarproject.api.forum.ForumConstants.TIME;
 import static org.briarproject.api.forum.ForumConstants.TO_BE_SHARED_BY_US;
 import static org.briarproject.api.forum.ForumConstants.TYPE;
 import static org.briarproject.api.forum.ForumManager.RemoveForumHook;
-import static org.briarproject.api.forum.InviteeProtocolState.AWAIT_INVITATION;
-import static org.briarproject.api.forum.InviteeProtocolState.AWAIT_LOCAL_RESPONSE;
-import static org.briarproject.api.forum.SharerProtocolState.PREPARE_INVITATION;
+import static org.briarproject.api.forum.ForumSharingMessage.BaseMessage;
+import static org.briarproject.api.forum.ForumSharingMessage.Invitation;
+import static org.briarproject.forum.ForumSharingSessionState.fromBdfDictionary;
+import static org.briarproject.forum.SharerSessionState.Action;
 
 class ForumSharingManagerImpl extends BdfIncomingMessageHook
 		implements ForumSharingManager, Client, RemoveForumHook,
@@ -111,6 +103,7 @@ class ForumSharingManagerImpl extends BdfIncomingMessageHook
 	private final MetadataEncoder metadataEncoder;
 	private final SecureRandom random;
 	private final PrivateGroupFactory privateGroupFactory;
+	private final ForumFactory forumFactory;
 	private final Clock clock;
 	private final Group localGroup;
 
@@ -119,7 +112,7 @@ class ForumSharingManagerImpl extends BdfIncomingMessageHook
 			MessageQueueManager messageQueueManager, ClientHelper clientHelper,
 			MetadataParser metadataParser, MetadataEncoder metadataEncoder,
 			SecureRandom random, PrivateGroupFactory privateGroupFactory,
-			Clock clock) {
+			ForumFactory forumFactory, Clock clock) {
 
 		super(clientHelper, metadataParser);
 		this.db = db;
@@ -128,6 +121,7 @@ class ForumSharingManagerImpl extends BdfIncomingMessageHook
 		this.metadataEncoder = metadataEncoder;
 		this.random = random;
 		this.privateGroupFactory = privateGroupFactory;
+		this.forumFactory = forumFactory;
 		this.clock = clock;
 		localGroup = privateGroupFactory.createLocalGroup(getClientId());
 	}
@@ -163,16 +157,18 @@ class ForumSharingManagerImpl extends BdfIncomingMessageHook
 
 	@Override
 	public void removingContact(Transaction txn, Contact c) throws DbException {
+		// query for this contact c
+		BdfDictionary query = BdfDictionary.of(
+				new BdfEntry(CONTACT_ID, c.getId().getInt())
+		);
+
 		// clean up session states with that contact from localGroup
-		Long id = (long) c.getId().getInt();
 		try {
 			Map<MessageId, BdfDictionary> map = clientHelper
-					.getMessageMetadataAsDictionary(txn, localGroup.getId());
+					.getMessageMetadataAsDictionary(txn, localGroup.getId(),
+							query);
 			for (Map.Entry<MessageId, BdfDictionary> entry : map.entrySet()) {
-				BdfDictionary d = entry.getValue();
-				if (id.equals(d.getLong(CONTACT_ID))) {
-					deleteMessage(txn, entry.getKey());
-				}
+				deleteMessage(txn, entry.getKey());
 			}
 		} catch (FormatException e) {
 			if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
@@ -184,11 +180,12 @@ class ForumSharingManagerImpl extends BdfIncomingMessageHook
 
 	@Override
 	protected void incomingMessage(Transaction txn, Message m, BdfList body,
-			BdfDictionary msg) throws DbException, FormatException {
+			BdfDictionary d) throws DbException, FormatException {
 
-		SessionId sessionId = new SessionId(msg.getRaw(SESSION_ID));
-		long type = msg.getLong(TYPE);
-		if (type == SHARE_MSG_TYPE_INVITATION) {
+		BaseMessage msg = BaseMessage.from(m.getGroupId(), d);
+		SessionId sessionId = msg.getSessionId();
+
+		if (msg.getType() == SHARE_MSG_TYPE_INVITATION) {
 			// we are an invitee who just received a new invitation
 			boolean stateExists = true;
 			try {
@@ -203,43 +200,46 @@ class ForumSharingManagerImpl extends BdfIncomingMessageHook
 				if (stateExists) throw new FormatException();
 
 				// check if forum can be shared
-				Forum f = forumManager.createForum(msg.getString(FORUM_NAME),
-						msg.getRaw(FORUM_SALT));
+				Invitation invitation = (Invitation) msg;
+				Forum f = forumFactory.createForum(invitation.getForumName(),
+						invitation.getForumSalt());
 				ContactId contactId = getContactId(txn, m.getGroupId());
 				Contact contact = db.getContact(txn, contactId);
 				if (!canBeShared(txn, f.getId(), contact))
 					throw new FormatException();
 
 				// initialize state and process invitation
-				BdfDictionary state =
-						initializeInviteeState(txn, contactId, msg);
-				InviteeEngine engine = new InviteeEngine();
-				processStateUpdate(txn, m.getId(),
+				InviteeSessionState state =
+						initializeInviteeState(txn, contactId, invitation);
+				InviteeEngine engine = new InviteeEngine(forumFactory);
+				processInviteeStateUpdate(txn, m.getId(),
 						engine.onMessageReceived(state, msg));
 			} catch (FormatException e) {
 				if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
 				deleteMessage(txn, m.getId());
 			}
-		} else if (type == SHARE_MSG_TYPE_ACCEPT ||
-				type == SHARE_MSG_TYPE_DECLINE) {
+		} else if (msg.getType() == SHARE_MSG_TYPE_ACCEPT ||
+				msg.getType() == SHARE_MSG_TYPE_DECLINE) {
 			// we are a sharer who just received a response
-			BdfDictionary state = getSessionState(txn, sessionId, true);
+			SharerSessionState state = getSessionStateForSharer(txn, sessionId);
 			SharerEngine engine = new SharerEngine();
-			processStateUpdate(txn, m.getId(),
+			processSharerStateUpdate(txn, m.getId(),
 					engine.onMessageReceived(state, msg));
-		} else if (type == SHARE_MSG_TYPE_LEAVE ||
-				type == SHARE_MSG_TYPE_ABORT) {
+		} else if (msg.getType() == SHARE_MSG_TYPE_LEAVE ||
+				msg.getType() == SHARE_MSG_TYPE_ABORT) {
 			// we don't know who we are, so figure it out
-			BdfDictionary state = getSessionState(txn, sessionId, true);
-			if (state.getBoolean(IS_SHARER)) {
+			ForumSharingSessionState s = getSessionState(txn, sessionId, true);
+			if (s instanceof SharerSessionState) {
 				// we are a sharer and the invitee wants to leave or abort
+				SharerSessionState state = (SharerSessionState) s;
 				SharerEngine engine = new SharerEngine();
-				processStateUpdate(txn, m.getId(),
+				processSharerStateUpdate(txn, m.getId(),
 						engine.onMessageReceived(state, msg));
 			} else {
 				// we are an invitee and the sharer wants to leave or abort
-				InviteeEngine engine = new InviteeEngine();
-				processStateUpdate(txn, m.getId(),
+				InviteeSessionState state = (InviteeSessionState) s;
+				InviteeEngine engine = new InviteeEngine(forumFactory);
+				processInviteeStateUpdate(txn, m.getId(),
 						engine.onMessageReceived(state, msg));
 			}
 		} else {
@@ -261,19 +261,18 @@ class ForumSharingManagerImpl extends BdfIncomingMessageHook
 		try {
 			// initialize local state for sharer
 			Forum f = forumManager.getForum(txn, groupId);
-			BdfDictionary localState = initializeSharerState(txn, f, contactId);
+			SharerSessionState localState =
+					initializeSharerState(txn, f, contactId);
 
-			// define action
-			BdfDictionary localAction = new BdfDictionary();
-			localAction.put(TYPE, SHARE_MSG_TYPE_INVITATION);
+			// add invitation message to local state to be available for engine
 			if (!StringUtils.isNullOrEmpty(msg)) {
-				localAction.put(INVITATION_MSG, msg);
+				localState.setMessage(msg);
 			}
 
 			// start engine and process its state update
 			SharerEngine engine = new SharerEngine();
-			processStateUpdate(txn, null,
-					engine.onLocalAction(localState, localAction));
+			processSharerStateUpdate(txn, null,
+					engine.onLocalAction(localState, Action.LOCAL_INVITATION));
 
 			txn.setComplete();
 		} catch (FormatException e) {
@@ -284,25 +283,26 @@ class ForumSharingManagerImpl extends BdfIncomingMessageHook
 	}
 
 	@Override
-	public void respondToInvitation(Forum f, boolean accept)
+	public void respondToInvitation(Forum f, Contact c, boolean accept)
 			throws DbException {
 
 		Transaction txn = db.startTransaction(false);
 		try {
 			// find session state based on forum
-			BdfDictionary localState = getSessionStateForResponse(txn, f);
+			InviteeSessionState localState =
+					getSessionStateForResponse(txn, f, c);
 
 			// define action
-			BdfDictionary localAction = new BdfDictionary();
+			InviteeSessionState.Action localAction;
 			if (accept) {
-				localAction.put(TYPE, SHARE_MSG_TYPE_ACCEPT);
+				localAction = InviteeSessionState.Action.LOCAL_ACCEPT;
 			} else {
-				localAction.put(TYPE, SHARE_MSG_TYPE_DECLINE);
+				localAction = InviteeSessionState.Action.LOCAL_DECLINE;
 			}
 
 			// start engine and process its state update
-			InviteeEngine engine = new InviteeEngine();
-			processStateUpdate(txn, null,
+			InviteeEngine engine = new InviteeEngine(forumFactory);
+			processInviteeStateUpdate(txn, null,
 					engine.onLocalAction(localState, localAction));
 
 			txn.setComplete();
@@ -317,6 +317,11 @@ class ForumSharingManagerImpl extends BdfIncomingMessageHook
 	public Collection<ForumInvitationMessage> getForumInvitationMessages(
 			ContactId contactId) throws DbException {
 
+		// query for all invitations
+		BdfDictionary query = BdfDictionary.of(
+				new BdfEntry(TYPE, SHARE_MSG_TYPE_INVITATION)
+		);
+
 		Transaction txn = db.startTransaction(false);
 		try {
 			Contact contact = db.getContact(txn, contactId);
@@ -325,36 +330,32 @@ class ForumSharingManagerImpl extends BdfIncomingMessageHook
 			Collection<ForumInvitationMessage> list =
 					new ArrayList<ForumInvitationMessage>();
 			Map<MessageId, BdfDictionary> map = clientHelper
-					.getMessageMetadataAsDictionary(txn, group.getId());
+					.getMessageMetadataAsDictionary(txn, group.getId(), query);
 			for (Map.Entry<MessageId, BdfDictionary> m : map.entrySet()) {
-				BdfDictionary msg = m.getValue();
+				BdfDictionary d = m.getValue();
 				try {
-					if (msg.getLong(TYPE) != SHARE_MSG_TYPE_INVITATION)
-						continue;
-
+					Invitation msg = Invitation.from(group.getId(), d);
 					MessageStatus status =
 							db.getMessageStatus(txn, contactId, m.getKey());
-					SessionId sessionId = new SessionId(msg.getRaw(SESSION_ID));
-					String name = msg.getString(FORUM_NAME);
-					String message = msg.getOptionalString(INVITATION_MSG);
-					long time = msg.getLong(TIME);
-					boolean local = msg.getBoolean(LOCAL);
-					boolean read = msg.getBoolean(READ, false);
+					long time = d.getLong(TIME);
+					boolean local = d.getBoolean(LOCAL);
+					boolean read = d.getBoolean(READ, false);
 					boolean available = false;
 					if (!local) {
 						// figure out whether the forum is still available
-						BdfDictionary sessionState =
-								getSessionState(txn, sessionId, true);
-						InviteeProtocolState state = InviteeProtocolState
-								.fromValue(
-										sessionState.getLong(STATE).intValue());
-						available = state == AWAIT_LOCAL_RESPONSE;
+						ForumSharingSessionState s =
+								getSessionState(txn, msg.getSessionId(), true);
+						if (!(s instanceof InviteeSessionState))
+							continue;
+						available = ((InviteeSessionState) s).getState() ==
+								InviteeSessionState.State.AWAIT_LOCAL_RESPONSE;
 					}
 					ForumInvitationMessage im =
-							new ForumInvitationMessage(m.getKey(), sessionId,
-									contactId, name, message, available, time,
-									local, status.isSent(), status.isSeen(),
-									read);
+							new ForumInvitationMessage(m.getKey(),
+									msg.getSessionId(), contactId,
+									msg.getForumName(), msg.getMessage(),
+									available, time, local, status.isSent(),
+									status.isSeen(), read);
 					list.add(im);
 				} catch (FormatException e) {
 					if (LOG.isLoggable(WARNING))
@@ -441,15 +442,15 @@ class ForumSharingManagerImpl extends BdfIncomingMessageHook
 	}
 
 	@Override
-	public Collection<ContactId> getSharedWith(GroupId g) throws DbException {
+	public Collection<Contact> getSharedWith(GroupId g) throws DbException {
 		try {
-			List<ContactId> shared = new ArrayList<ContactId>();
+			List<Contact> shared = new ArrayList<Contact>();
 			Transaction txn = db.startTransaction(true);
 			try {
 				for (Contact c : db.getContacts(txn)) {
 					GroupId contactGroup = getContactGroup(c).getId();
 					if (listContains(txn, contactGroup, g, SHARED_BY_US))
-						shared.add(c.getId());
+						shared.add(c);
 				}
 				txn.setComplete();
 			} finally {
@@ -487,7 +488,7 @@ class ForumSharingManagerImpl extends BdfIncomingMessageHook
 		}
 	}
 
-	private BdfDictionary initializeSharerState(Transaction txn, Forum f,
+	private SharerSessionState initializeSharerState(Transaction txn, Forum f,
 			ContactId contactId) throws FormatException, DbException {
 
 		Contact c = db.getContact(txn, contactId);
@@ -499,34 +500,28 @@ class ForumSharingManagerImpl extends BdfIncomingMessageHook
 		random.nextBytes(salt.getBytes());
 		Message m = clientHelper.createMessage(localGroup.getId(), now,
 				BdfList.of(salt));
-		MessageId sessionId = m.getId();
+		SessionId sessionId = new SessionId(m.getId().getBytes());
 
-		BdfDictionary d = new BdfDictionary();
-		d.put(SESSION_ID, sessionId);
-		d.put(STORAGE_ID, sessionId);
-		d.put(GROUP_ID, group.getId());
-		d.put(IS_SHARER, true);
-		d.put(STATE, PREPARE_INVITATION.getValue());
-		d.put(CONTACT_ID, contactId.getInt());
-		d.put(FORUM_ID, f.getId());
-		d.put(FORUM_NAME, f.getName());
-		d.put(FORUM_SALT, f.getSalt());
+		SharerSessionState s = new SharerSessionState(sessionId, sessionId,
+				group.getId(), SharerSessionState.State.PREPARE_INVITATION,
+				contactId, f.getId(), f.getName(), f.getSalt());
 
 		// save local state to database
+		BdfDictionary d = s.toBdfDictionary();
 		clientHelper.addLocalMessage(txn, m, getClientId(), d, false);
 
-		return d;
+		return s;
 	}
 
-	private BdfDictionary initializeInviteeState(Transaction txn,
-			ContactId contactId, BdfDictionary msg)
+	private InviteeSessionState initializeInviteeState(Transaction txn,
+			ContactId contactId, Invitation msg)
 			throws FormatException, DbException {
 
 		Contact c = db.getContact(txn, contactId);
 		Group group = getContactGroup(c);
-		String name = msg.getString(FORUM_NAME);
-		byte[] salt = msg.getRaw(FORUM_SALT);
-		Forum f = forumManager.createForum(name, salt);
+		String name = msg.getForumName();
+		byte[] salt = msg.getForumSalt();
+		Forum f = forumFactory.createForum(name, salt);
 
 		// create local message to keep engine state
 		long now = clock.currentTimeMillis();
@@ -535,105 +530,129 @@ class ForumSharingManagerImpl extends BdfIncomingMessageHook
 		Message m = clientHelper.createMessage(localGroup.getId(), now,
 				BdfList.of(mSalt));
 
-		BdfDictionary d = new BdfDictionary();
-		d.put(SESSION_ID, msg.getRaw(SESSION_ID));
-		d.put(STORAGE_ID, m.getId());
-		d.put(GROUP_ID, group.getId());
-		d.put(IS_SHARER, false);
-		d.put(STATE, AWAIT_INVITATION.getValue());
-		d.put(CONTACT_ID, contactId.getInt());
-		d.put(FORUM_ID, f.getId());
-		d.put(FORUM_NAME, name);
-		d.put(FORUM_SALT, salt);
+		InviteeSessionState s = new InviteeSessionState(msg.getSessionId(),
+				m.getId(), group.getId(),
+				InviteeSessionState.State.AWAIT_INVITATION, contactId,
+				f.getId(), f.getName(), f.getSalt());
 
 		// save local state to database
+		BdfDictionary d = s.toBdfDictionary();
 		clientHelper.addLocalMessage(txn, m, getClientId(), d, false);
 
-		return d;
+		return s;
 	}
 
-	private BdfDictionary getSessionState(Transaction txn, SessionId sessionId,
-			boolean warn) throws DbException, FormatException {
-
-		try {
-			// we should be able to get the sharer state directly from sessionId
-			return clientHelper.getMessageMetadataAsDictionary(txn, sessionId);
-		} catch (NoSuchMessageException e) {
-			// State not found directly, so iterate over all states
-			// to find state for invitee
-			Map<MessageId, BdfDictionary> map = clientHelper
-					.getMessageMetadataAsDictionary(txn, localGroup.getId());
-			for (Map.Entry<MessageId, BdfDictionary> m : map.entrySet()) {
-				BdfDictionary state = m.getValue();
-				if (Arrays.equals(state.getRaw(SESSION_ID),
-						sessionId.getBytes())) {
-					return state;
-				}
-			}
-			if (warn && LOG.isLoggable(WARNING)) {
-				LOG.warning(
-						"No session state found for message with session ID " +
-								Arrays.hashCode(sessionId.getBytes()));
-			}
-			throw new FormatException();
-		}
-	}
-
-	private BdfDictionary getSessionStateForResponse(Transaction txn, Forum f)
+	private ForumSharingSessionState getSessionState(Transaction txn,
+			SessionId sessionId, boolean warn)
 			throws DbException, FormatException {
 
-		Map<MessageId, BdfDictionary> map = clientHelper
-				.getMessageMetadataAsDictionary(txn, localGroup.getId());
-		for (Map.Entry<MessageId, BdfDictionary> m : map.entrySet()) {
-			BdfDictionary d = m.getValue();
-			try {
-				InviteeProtocolState state = InviteeProtocolState
-						.fromValue(d.getLong(STATE).intValue());
-				if (state == AWAIT_LOCAL_RESPONSE) {
-					byte[] id = d.getRaw(FORUM_ID);
-					if (Arrays.equals(f.getId().getBytes(), id)) {
-						// Note that there should always be only one session
-						// in this state for the same forum
-						return d;
-					}
-				}
-			} catch (FormatException e) {
-				if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
+		try {
+			return getSessionStateForSharer(txn, sessionId);
+		} catch (NoSuchMessageException e) {
+			// State not found directly, so query for state for invitee
+			BdfDictionary query = BdfDictionary.of(
+					new BdfEntry(SESSION_ID, sessionId)
+			);
+
+			Map<MessageId, BdfDictionary> map = clientHelper
+					.getMessageMetadataAsDictionary(txn, localGroup.getId(),
+							query);
+
+			if (map.size() > 1 && LOG.isLoggable(WARNING)) {
+				LOG.warning(
+						"More than one session state found for message with session ID " +
+								Arrays.hashCode(sessionId.getBytes()));
 			}
+			if (map.isEmpty()) {
+				if (warn && LOG.isLoggable(WARNING)) {
+					LOG.warning(
+							"No session state found for message with session ID " +
+									Arrays.hashCode(sessionId.getBytes()));
+				}
+				throw new FormatException();
+			}
+			return fromBdfDictionary(map.values().iterator().next());
 		}
-		throw new DbException();
 	}
 
-	private BdfDictionary getSessionStateForLeaving(Transaction txn, Forum f,
-			ContactId c) throws DbException, FormatException {
+	private SharerSessionState getSessionStateForSharer(Transaction txn,
+			SessionId sessionId)
+			throws DbException, FormatException {
+
+		// we should be able to get the sharer state directly from sessionId
+		BdfDictionary d =
+				clientHelper.getMessageMetadataAsDictionary(txn, sessionId);
+
+		if (!d.getBoolean(IS_SHARER)) throw new FormatException();
+
+		return (SharerSessionState) fromBdfDictionary(d);
+	}
+
+	private InviteeSessionState getSessionStateForResponse(Transaction txn,
+			Forum f, Contact c) throws DbException, FormatException {
+
+		// query for invitee states for that forum in state await response
+		BdfDictionary query = BdfDictionary.of(
+				new BdfEntry(IS_SHARER, false),
+				new BdfEntry(CONTACT_ID, c.getId().getInt()),
+				new BdfEntry(FORUM_ID, f.getId()),
+				new BdfEntry(STATE,
+						InviteeSessionState.State.AWAIT_LOCAL_RESPONSE
+								.getValue())
+		);
 
 		Map<MessageId, BdfDictionary> map = clientHelper
-				.getMessageMetadataAsDictionary(txn, localGroup.getId());
+				.getMessageMetadataAsDictionary(txn, localGroup.getId(), query);
+
+		if (map.size() > 1 && LOG.isLoggable(WARNING)) {
+			LOG.warning(
+					"More than one session state found for forum with ID " +
+							Arrays.hashCode(f.getId().getBytes()) +
+							" in state AWAIT_LOCAL_RESPONSE for contact " +
+							c.getAuthor().getName());
+		}
+		if (map.isEmpty()) {
+			if (LOG.isLoggable(WARNING)) {
+				LOG.warning(
+						"No session state found for forum with ID " +
+								Arrays.hashCode(f.getId().getBytes()) +
+								" in state AWAIT_LOCAL_RESPONSE");
+			}
+			throw new DbException();
+		}
+		return (InviteeSessionState) fromBdfDictionary(
+				map.values().iterator().next());
+	}
+
+	private ForumSharingSessionState getSessionStateForLeaving(Transaction txn,
+			Forum f, ContactId c) throws DbException, FormatException {
+
+		BdfDictionary query = BdfDictionary.of(
+				new BdfEntry(CONTACT_ID, c.getInt()),
+				new BdfEntry(FORUM_ID, f.getId())
+		);
+		Map<MessageId, BdfDictionary> map = clientHelper
+				.getMessageMetadataAsDictionary(txn, localGroup.getId(), query);
 		for (Map.Entry<MessageId, BdfDictionary> m : map.entrySet()) {
 			BdfDictionary d = m.getValue();
 			try {
-				// check that this session is with the right contact
-				if (c.getInt() != d.getLong(CONTACT_ID)) continue;
+				ForumSharingSessionState s = fromBdfDictionary(d);
+
 				// check that a forum get be left in current session
-				int intState = d.getLong(STATE).intValue();
-				if (d.getBoolean(IS_SHARER)) {
-					SharerProtocolState state =
-							SharerProtocolState.fromValue(intState);
-					if (state.next(SharerAction.LOCAL_LEAVE) ==
-							SharerProtocolState.ERROR) continue;
+				if (s instanceof SharerSessionState) {
+					SharerSessionState state = (SharerSessionState) s;
+					SharerSessionState.State nextState =
+							state.getState().next(Action.LOCAL_LEAVE);
+					if (nextState != SharerSessionState.State.ERROR) {
+						return state;
+					}
 				} else {
-					InviteeProtocolState state = InviteeProtocolState
-							.fromValue(intState);
-					if (state.next(InviteeAction.LOCAL_LEAVE) ==
-							InviteeProtocolState.ERROR) continue;
-				}
-				// check that this state actually concerns this forum
-				String name = d.getString(FORUM_NAME);
-				byte[] salt = d.getRaw(FORUM_SALT);
-				if (name.equals(f.getName()) &&
-						Arrays.equals(salt, f.getSalt())) {
-					// TODO what happens when there is more than one invitation?
-					return d;
+					InviteeSessionState state = (InviteeSessionState) s;
+					InviteeSessionState.State nextState = state.getState()
+							.next(InviteeSessionState.Action.LOCAL_LEAVE);
+					if (nextState != InviteeSessionState.State.ERROR) {
+						return state;
+					}
 				}
 			} catch (FormatException e) {
 				if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
@@ -643,20 +662,20 @@ class ForumSharingManagerImpl extends BdfIncomingMessageHook
 	}
 
 	private void processStateUpdate(Transaction txn, MessageId messageId,
-			StateUpdate<BdfDictionary, BdfDictionary> result)
+			StateUpdate<ForumSharingSessionState, BaseMessage> result)
 			throws DbException, FormatException {
 
 		// perform actions based on new local state
 		performTasks(txn, result.localState);
 
 		// save new local state
-		MessageId storageId =
-				new MessageId(result.localState.getRaw(STORAGE_ID));
-		clientHelper.mergeMessageMetadata(txn, storageId, result.localState);
+		MessageId storageId = result.localState.getStorageId();
+		clientHelper.mergeMessageMetadata(txn, storageId,
+				result.localState.toBdfDictionary());
 
 		// send messages
-		for (BdfDictionary d : result.toSend) {
-			sendMessage(txn, d);
+		for (BaseMessage msg : result.toSend) {
+			sendMessage(txn, msg);
 		}
 
 		// broadcast events
@@ -674,25 +693,48 @@ class ForumSharingManagerImpl extends BdfIncomingMessageHook
 		}
 	}
 
-	private void performTasks(Transaction txn, BdfDictionary localState)
+	private void processSharerStateUpdate(Transaction txn, MessageId messageId,
+			StateUpdate<SharerSessionState, BaseMessage> result)
+			throws DbException, FormatException {
+
+		StateUpdate<ForumSharingSessionState, BaseMessage> r =
+				new StateUpdate<ForumSharingSessionState, BaseMessage>(
+						result.deleteMessage, result.deleteState,
+						result.localState, result.toSend, result.toBroadcast);
+
+		processStateUpdate(txn, messageId, r);
+	}
+
+	private void processInviteeStateUpdate(Transaction txn, MessageId messageId,
+			StateUpdate<InviteeSessionState, BaseMessage> result)
+			throws DbException, FormatException {
+
+		StateUpdate<ForumSharingSessionState, BaseMessage> r =
+				new StateUpdate<ForumSharingSessionState, BaseMessage>(
+						result.deleteMessage, result.deleteState,
+						result.localState, result.toSend, result.toBroadcast);
+
+		processStateUpdate(txn, messageId, r);
+	}
+
+	private void performTasks(Transaction txn, ForumSharingSessionState localState)
 			throws FormatException, DbException {
 
-		if (!localState.containsKey(TASK)) return;
+		if (localState.getTask() == -1) return;
 
 		// remember task and remove it from localState
-		long task = localState.getLong(TASK);
-		localState.put(TASK, BdfDictionary.NULL_VALUE);
+		long task = localState.getTask();
+		localState.setTask(-1);
 
 		// get group ID for later
-		GroupId groupId = new GroupId(localState.getRaw(GROUP_ID));
+		GroupId groupId = localState.getGroupId();
 		// get contact ID for later
-		ContactId contactId =
-				new ContactId(localState.getLong(CONTACT_ID).intValue());
+		ContactId contactId = localState.getContactId();
 
 		// get forum for later
-		String name = localState.getString(FORUM_NAME);
-		byte[] salt = localState.getRaw(FORUM_SALT);
-		Forum f = forumManager.createForum(name, salt);
+		String name = localState.getForumName();
+		byte[] salt = localState.getForumSalt();
+		Forum f = forumFactory.createForum(name, salt);
 
 		// perform tasks
 		if (task == TASK_ADD_FORUM_TO_LIST_SHARED_WITH_US) {
@@ -725,50 +767,23 @@ class ForumSharingManagerImpl extends BdfIncomingMessageHook
 		}
 	}
 
-	private void sendMessage(Transaction txn, BdfDictionary m)
+	private void sendMessage(Transaction txn, BaseMessage m)
 			throws FormatException, DbException {
 
-		BdfList list = encodeMessage(m);
-		byte[] body = clientHelper.toByteArray(list);
-		GroupId groupId = new GroupId(m.getRaw(GROUP_ID));
-		Group group = db.getGroup(txn, groupId);
+		byte[] body = clientHelper.toByteArray(m.toBdfList());
+		Group group = db.getGroup(txn, m.getGroupId());
 		long timestamp = clock.currentTimeMillis();
 
 		// add message itself as metadata
-		m.put(LOCAL, true);
-		m.put(TIME, timestamp);
-		Metadata meta = metadataEncoder.encode(m);
+		BdfDictionary d = m.toBdfDictionary();
+		d.put(LOCAL, true);
+		d.put(TIME, timestamp);
+		Metadata meta = metadataEncoder.encode(d);
 
 		messageQueueManager
 				.sendMessage(txn, group, timestamp, body, meta);
 	}
 
-	private BdfList encodeMessage(BdfDictionary m) throws FormatException {
-		long type = m.getLong(TYPE);
-
-		BdfList list;
-		if (type == SHARE_MSG_TYPE_INVITATION) {
-			list = BdfList.of(type,
-					m.getRaw(SESSION_ID),
-					m.getString(FORUM_NAME),
-					m.getRaw(FORUM_SALT)
-			);
-			String msg = m.getOptionalString(INVITATION_MSG);
-			if (msg != null) list.add(msg);
-		} else if (type == SHARE_MSG_TYPE_ACCEPT) {
-			list = BdfList.of(type, m.getRaw(SESSION_ID));
-		} else if (type == SHARE_MSG_TYPE_DECLINE) {
-			list = BdfList.of(type, m.getRaw(SESSION_ID));
-		} else if (type == SHARE_MSG_TYPE_LEAVE) {
-			list = BdfList.of(type, m.getRaw(SESSION_ID));
-		} else if (type == SHARE_MSG_TYPE_ABORT) {
-			list = BdfList.of(type, m.getRaw(SESSION_ID));
-		} else {
-			throw new FormatException();
-		}
-		return list;
-	}
-
 	private Group getContactGroup(Contact c) {
 		return privateGroupFactory.createPrivateGroup(CLIENT_ID, c);
 	}
@@ -783,17 +798,18 @@ class ForumSharingManagerImpl extends BdfIncomingMessageHook
 	private void leaveForum(Transaction txn, ContactId c, Forum f)
 			throws DbException, FormatException {
 
-		BdfDictionary state = getSessionStateForLeaving(txn, f, c);
-		BdfDictionary action = new BdfDictionary();
-		action.put(TYPE, SHARE_MSG_TYPE_LEAVE);
-		if (state.getBoolean(IS_SHARER)) {
+		ForumSharingSessionState state = getSessionStateForLeaving(txn, f, c);
+		if (state instanceof SharerSessionState) {
+			Action action = Action.LOCAL_LEAVE;
 			SharerEngine engine = new SharerEngine();
-			processStateUpdate(txn, null,
-					engine.onLocalAction(state, action));
+			processSharerStateUpdate(txn, null,
+					engine.onLocalAction((SharerSessionState) state, action));
 		} else {
-			InviteeEngine engine = new InviteeEngine();
-			processStateUpdate(txn, null,
-					engine.onLocalAction(state, action));
+			InviteeSessionState.Action action =
+					InviteeSessionState.Action.LOCAL_LEAVE;
+			InviteeEngine engine = new InviteeEngine(forumFactory);
+			processInviteeStateUpdate(txn, null,
+					engine.onLocalAction((InviteeSessionState) state, action));
 		}
 	}
 
@@ -859,7 +875,7 @@ class ForumSharingManagerImpl extends BdfIncomingMessageHook
 		List<Forum> forums = new ArrayList<Forum>(list.size());
 		for (int i = 0; i < list.size(); i++) {
 			BdfList forum = list.getList(i);
-			forums.add(forumManager
+			forums.add(forumFactory
 					.createForum(forum.getString(0), forum.getRaw(1)));
 		}
 		return forums;

briar-core/src/org/briarproject/forum/ForumSharingSessionState.java

@@ -0,0 +1,119 @@
+package org.briarproject.forum;
+
+import org.briarproject.api.FormatException;
+import org.briarproject.api.clients.SessionId;
+import org.briarproject.api.contact.ContactId;
+import org.briarproject.api.data.BdfDictionary;
+import org.briarproject.api.sync.GroupId;
+import org.briarproject.api.sync.MessageId;
+
+import static org.briarproject.api.forum.ForumConstants.CONTACT_ID;
+import static org.briarproject.api.forum.ForumConstants.FORUM_ID;
+import static org.briarproject.api.forum.ForumConstants.FORUM_NAME;
+import static org.briarproject.api.forum.ForumConstants.FORUM_SALT;
+import static org.briarproject.api.forum.ForumConstants.GROUP_ID;
+import static org.briarproject.api.forum.ForumConstants.IS_SHARER;
+import static org.briarproject.api.forum.ForumConstants.SESSION_ID;
+import static org.briarproject.api.forum.ForumConstants.STATE;
+import static org.briarproject.api.forum.ForumConstants.STORAGE_ID;
+
+// This class is not thread-safe
+public abstract class ForumSharingSessionState {
+
+	private final SessionId sessionId;
+	private final MessageId storageId;
+	private final GroupId groupId;
+	private final ContactId contactId;
+	private final GroupId forumId;
+	private final String forumName;
+	private final byte[] forumSalt;
+	private int task = -1; // TODO get rid of task, see #376
+
+	public ForumSharingSessionState(SessionId sessionId, MessageId storageId,
+			GroupId groupId, ContactId contactId, GroupId forumId,
+			String forumName, byte[] forumSalt) {
+
+		this.sessionId = sessionId;
+		this.storageId = storageId;
+		this.groupId = groupId;
+		this.contactId = contactId;
+		this.forumId = forumId;
+		this.forumName = forumName;
+		this.forumSalt = forumSalt;
+	}
+
+	public static ForumSharingSessionState fromBdfDictionary(BdfDictionary d)
+			throws FormatException{
+
+		SessionId sessionId = new SessionId(d.getRaw(SESSION_ID));
+		MessageId messageId = new MessageId(d.getRaw(STORAGE_ID));
+		GroupId groupId = new GroupId(d.getRaw(GROUP_ID));
+		ContactId contactId = new ContactId(d.getLong(CONTACT_ID).intValue());
+		GroupId forumId = new GroupId(d.getRaw(FORUM_ID));
+		String forumName = d.getString(FORUM_NAME);
+		byte[] forumSalt = d.getRaw(FORUM_SALT);
+
+		int intState = d.getLong(STATE).intValue();
+		if (d.getBoolean(IS_SHARER)) {
+			SharerSessionState.State state =
+					SharerSessionState.State.fromValue(intState);
+			return new SharerSessionState(sessionId, messageId, groupId, state,
+					contactId, forumId, forumName, forumSalt);
+		} else {
+			InviteeSessionState.State state =
+					InviteeSessionState.State.fromValue(intState);
+			return new InviteeSessionState(sessionId, messageId, groupId, state,
+					contactId, forumId, forumName, forumSalt);
+		}
+	}
+
+	public BdfDictionary toBdfDictionary() {
+		BdfDictionary d = new BdfDictionary();
+		d.put(SESSION_ID, getSessionId());
+		d.put(STORAGE_ID, getStorageId());
+		d.put(GROUP_ID, getGroupId());
+		d.put(CONTACT_ID, getContactId().getInt());
+		d.put(FORUM_ID, getForumId());
+		d.put(FORUM_NAME, getForumName());
+		d.put(FORUM_SALT, getForumSalt());
+
+		return d;
+	}
+
+	public SessionId getSessionId() {
+		return sessionId;
+	}
+
+	public MessageId getStorageId() {
+		return storageId;
+	}
+
+	public GroupId getGroupId() {
+		return groupId;
+	}
+
+	public ContactId getContactId() {
+		return contactId;
+	}
+
+	public GroupId getForumId() {
+		return forumId;
+	}
+
+	public String getForumName() {
+		return forumName;
+	}
+
+	public byte[] getForumSalt() {
+		return forumSalt;
+	}
+
+	public void setTask(int task) {
+		this.task = task;
+	}
+
+	public int getTask() {
+		return task;
+	}
+
+}

briar-core/src/org/briarproject/forum/ForumSharingValidator.java

@@ -3,6 +3,7 @@ package org.briarproject.forum;
 import org.briarproject.api.FormatException;
 import org.briarproject.api.clients.ClientHelper;
 import org.briarproject.api.clients.SessionId;
+import org.briarproject.api.clients.BdfMessageContext;
 import org.briarproject.api.data.BdfDictionary;
 import org.briarproject.api.data.BdfList;
 import org.briarproject.api.data.MetadataEncoder;
@@ -36,7 +37,7 @@ class ForumSharingValidator extends BdfMessageValidator {
 	}
 
 	@Override
-	protected BdfDictionary validateMessage(Message m, Group g,
+	protected BdfMessageContext validateMessage(Message m, Group g,
 			BdfList body) throws FormatException {
 
 		BdfDictionary d = new BdfDictionary();
@@ -73,9 +74,8 @@ class ForumSharingValidator extends BdfMessageValidator {
 		// Return the metadata
 		d.put(TYPE, type);
 		d.put(SESSION_ID, id);
-		d.put(GROUP_ID, m.getGroupId());
 		d.put(LOCAL, false);
 		d.put(TIME, m.getTimestamp());
-		return d;
+		return new BdfMessageContext(d);
 	}
 }

briar-core/src/org/briarproject/forum/InviteeEngine.java

@@ -3,65 +3,59 @@ package org.briarproject.forum;
 import org.briarproject.api.FormatException;
 import org.briarproject.api.clients.ProtocolEngine;
 import org.briarproject.api.contact.ContactId;
-import org.briarproject.api.data.BdfDictionary;
-import org.briarproject.api.data.BdfEntry;
 import org.briarproject.api.event.Event;
 import org.briarproject.api.event.ForumInvitationReceivedEvent;
 import org.briarproject.api.forum.Forum;
-import org.briarproject.api.forum.InviteeAction;
-import org.briarproject.api.forum.InviteeProtocolState;
+import org.briarproject.api.forum.ForumFactory;
 
-import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
 import java.util.logging.Logger;
 
 import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
-import static org.briarproject.api.forum.ForumConstants.CONTACT_ID;
-import static org.briarproject.api.forum.ForumConstants.FORUM_NAME;
-import static org.briarproject.api.forum.ForumConstants.FORUM_SALT;
-import static org.briarproject.api.forum.ForumConstants.GROUP_ID;
-import static org.briarproject.api.forum.ForumConstants.SESSION_ID;
 import static org.briarproject.api.forum.ForumConstants.SHARE_MSG_TYPE_ABORT;
 import static org.briarproject.api.forum.ForumConstants.SHARE_MSG_TYPE_ACCEPT;
 import static org.briarproject.api.forum.ForumConstants.SHARE_MSG_TYPE_DECLINE;
 import static org.briarproject.api.forum.ForumConstants.SHARE_MSG_TYPE_INVITATION;
 import static org.briarproject.api.forum.ForumConstants.SHARE_MSG_TYPE_LEAVE;
-import static org.briarproject.api.forum.ForumConstants.STATE;
-import static org.briarproject.api.forum.ForumConstants.TASK;
 import static org.briarproject.api.forum.ForumConstants.TASK_ADD_FORUM_TO_LIST_SHARED_WITH_US;
 import static org.briarproject.api.forum.ForumConstants.TASK_ADD_SHARED_FORUM;
 import static org.briarproject.api.forum.ForumConstants.TASK_REMOVE_FORUM_FROM_LIST_SHARED_WITH_US;
 import static org.briarproject.api.forum.ForumConstants.TASK_UNSHARE_FORUM_SHARED_WITH_US;
-import static org.briarproject.api.forum.ForumConstants.TYPE;
-import static org.briarproject.api.forum.InviteeAction.LOCAL_ABORT;
-import static org.briarproject.api.forum.InviteeAction.LOCAL_ACCEPT;
-import static org.briarproject.api.forum.InviteeAction.LOCAL_DECLINE;
-import static org.briarproject.api.forum.InviteeAction.LOCAL_LEAVE;
-import static org.briarproject.api.forum.InviteeAction.REMOTE_INVITATION;
-import static org.briarproject.api.forum.InviteeAction.REMOTE_LEAVE;
-import static org.briarproject.api.forum.InviteeProtocolState.ERROR;
-import static org.briarproject.api.forum.InviteeProtocolState.FINISHED;
-import static org.briarproject.api.forum.InviteeProtocolState.LEFT;
+import static org.briarproject.api.forum.ForumSharingMessage.SimpleMessage;
+import static org.briarproject.api.forum.ForumSharingMessage.BaseMessage;
+import static org.briarproject.forum.InviteeSessionState.Action;
+import static org.briarproject.forum.InviteeSessionState.Action.LOCAL_ABORT;
+import static org.briarproject.forum.InviteeSessionState.Action.LOCAL_ACCEPT;
+import static org.briarproject.forum.InviteeSessionState.Action.LOCAL_DECLINE;
+import static org.briarproject.forum.InviteeSessionState.Action.LOCAL_LEAVE;
+import static org.briarproject.forum.InviteeSessionState.Action.REMOTE_INVITATION;
+import static org.briarproject.forum.InviteeSessionState.Action.REMOTE_LEAVE;
+import static org.briarproject.forum.InviteeSessionState.State;
+import static org.briarproject.forum.InviteeSessionState.State.ERROR;
+import static org.briarproject.forum.InviteeSessionState.State.FINISHED;
+import static org.briarproject.forum.InviteeSessionState.State.LEFT;
 
 public class InviteeEngine
-		implements ProtocolEngine<BdfDictionary, BdfDictionary, BdfDictionary> {
+		implements ProtocolEngine<Action, InviteeSessionState, BaseMessage> {
 
+	private final ForumFactory forumFactory;
 	private static final Logger LOG =
 			Logger.getLogger(SharerEngine.class.getName());
 
+	InviteeEngine(ForumFactory forumFactory) {
+		this.forumFactory = forumFactory;
+	}
+
 	@Override
-	public StateUpdate<BdfDictionary, BdfDictionary> onLocalAction(
-			BdfDictionary localState, BdfDictionary localAction) {
+	public StateUpdate<InviteeSessionState, BaseMessage> onLocalAction(
+			InviteeSessionState localState, Action action) {
 
 		try {
-			InviteeProtocolState currentState =
-					getState(localState.getLong(STATE));
-			long type = localAction.getLong(TYPE);
-			InviteeAction action = InviteeAction.getLocal(type);
-			InviteeProtocolState nextState = currentState.next(action);
-			localState.put(STATE, nextState.getValue());
+			State currentState = localState.getState();
+			State nextState = currentState.next(action);
+			localState.setState(nextState);
 
 			if (action == LOCAL_ABORT && currentState != ERROR) {
 				return abortSession(currentState, localState);
@@ -74,37 +68,34 @@ public class InviteeEngine
 				}
 				return noUpdate(localState, true);
 			}
-			List<BdfDictionary> messages;
+			List<BaseMessage> messages;
 			List<Event> events = Collections.emptyList();
 
 			if (action == LOCAL_ACCEPT || action == LOCAL_DECLINE) {
-				BdfDictionary msg = BdfDictionary.of(
-						new BdfEntry(SESSION_ID, localState.getRaw(SESSION_ID)),
-						new BdfEntry(GROUP_ID, localState.getRaw(GROUP_ID))
-				);
+				BaseMessage msg;
 				if (action == LOCAL_ACCEPT) {
-					localState.put(TASK, TASK_ADD_SHARED_FORUM);
-					msg.put(TYPE, SHARE_MSG_TYPE_ACCEPT);
+					localState.setTask(TASK_ADD_SHARED_FORUM);
+					msg = new SimpleMessage(SHARE_MSG_TYPE_ACCEPT,
+							localState.getGroupId(), localState.getSessionId());
 				} else {
-					localState.put(TASK,
+					localState.setTask(
 							TASK_REMOVE_FORUM_FROM_LIST_SHARED_WITH_US);
-					msg.put(TYPE, SHARE_MSG_TYPE_DECLINE);
+					msg = new SimpleMessage(SHARE_MSG_TYPE_DECLINE,
+							localState.getGroupId(), localState.getSessionId());
 				}
 				messages = Collections.singletonList(msg);
 				logLocalAction(currentState, localState, msg);
 			}
 			else if (action == LOCAL_LEAVE) {
-				BdfDictionary msg = new BdfDictionary();
-				msg.put(TYPE, SHARE_MSG_TYPE_LEAVE);
-				msg.put(SESSION_ID, localState.getRaw(SESSION_ID));
-				msg.put(GROUP_ID, localState.getRaw(GROUP_ID));
+				BaseMessage msg = new SimpleMessage(SHARE_MSG_TYPE_LEAVE,
+						localState.getGroupId(), localState.getSessionId());
 				messages = Collections.singletonList(msg);
 				logLocalAction(currentState, localState, msg);
 			}
 			else {
 				throw new IllegalArgumentException("Unknown Local Action");
 			}
-			return new StateUpdate<BdfDictionary, BdfDictionary>(false,
+			return new StateUpdate<InviteeSessionState, BaseMessage>(false,
 					false, localState, messages, events);
 		} catch (FormatException e) {
 			throw new IllegalArgumentException(e);
@@ -112,18 +103,16 @@ public class InviteeEngine
 	}
 
 	@Override
-	public StateUpdate<BdfDictionary, BdfDictionary> onMessageReceived(
-			BdfDictionary localState, BdfDictionary msg) {
+	public StateUpdate<InviteeSessionState, BaseMessage> onMessageReceived(
+			InviteeSessionState localState, BaseMessage msg) {
 
 		try {
-			InviteeProtocolState currentState =
-					getState(localState.getLong(STATE));
-			long type = msg.getLong(TYPE);
-			InviteeAction action = InviteeAction.getRemote(type);
-			InviteeProtocolState nextState = currentState.next(action);
-			localState.put(STATE, nextState.getValue());
+			State currentState = localState.getState();
+			Action action = Action.getRemote(msg.getType());
+			State nextState = currentState.next(action);
+			localState.setState(nextState);
 
-			logMessageReceived(currentState, nextState, type, msg);
+			logMessageReceived(currentState, nextState, msg.getType(), msg);
 
 			if (nextState == ERROR) {
 				if (currentState != ERROR) {
@@ -133,7 +122,7 @@ public class InviteeEngine
 				}
 			}
 
-			List<BdfDictionary> messages = Collections.emptyList();
+			List<BaseMessage> messages = Collections.emptyList();
 			List<Event> events = Collections.emptyList();
 			boolean deleteMsg = false;
 
@@ -143,7 +132,7 @@ public class InviteeEngine
 			}
 			// the sharer left the forum she had shared with us
 			else if (action == REMOTE_LEAVE && currentState == FINISHED) {
-				localState.put(TASK, TASK_UNSHARE_FORUM_SHARED_WITH_US);
+				localState.setTask(TASK_UNSHARE_FORUM_SHARED_WITH_US);
 			}
 			else if (currentState == FINISHED) {
 				// ignore and delete messages coming in while in that state
@@ -152,74 +141,65 @@ public class InviteeEngine
 			}
 			// the sharer left the forum before we couldn't even respond
 			else if (action == REMOTE_LEAVE) {
-				localState.put(TASK, TASK_REMOVE_FORUM_FROM_LIST_SHARED_WITH_US);
+				localState.setTask(TASK_REMOVE_FORUM_FROM_LIST_SHARED_WITH_US);
 			}
 			// we have just received our invitation
 			else if (action == REMOTE_INVITATION) {
-				localState.put(TASK, TASK_ADD_FORUM_TO_LIST_SHARED_WITH_US);
-				// TODO how to get the proper group here?
-				Forum forum = new Forum(null, localState.getString(FORUM_NAME),
-						localState.getRaw(FORUM_SALT));
-				ContactId contactId = new ContactId(
-						localState.getLong(CONTACT_ID).intValue());
+				Forum forum = forumFactory
+						.createForum(localState.getForumName(),
+								localState.getForumSalt());
+				localState.setTask(TASK_ADD_FORUM_TO_LIST_SHARED_WITH_US);
+				ContactId contactId = localState.getContactId();
 				Event event = new ForumInvitationReceivedEvent(forum, contactId);
 				events = Collections.singletonList(event);
 			}
 			else {
 				throw new IllegalArgumentException("Bad state");
 			}
-			return new StateUpdate<BdfDictionary, BdfDictionary>(deleteMsg,
+			return new StateUpdate<InviteeSessionState, BaseMessage>(deleteMsg,
 					false, localState, messages, events);
 		} catch (FormatException e) {
 			throw new IllegalArgumentException(e);
 		}
 	}
 
-	private void logLocalAction(InviteeProtocolState state,
-			BdfDictionary localState, BdfDictionary msg) {
+	private void logLocalAction(State state,
+			InviteeSessionState localState, BaseMessage msg) {
 
 		if (!LOG.isLoggable(INFO)) return;
 
 		String a = "response";
-		if (msg.getLong(TYPE, -1L) == SHARE_MSG_TYPE_LEAVE) a = "leave";
+		if (msg.getType() == SHARE_MSG_TYPE_LEAVE) a = "leave";
 
-		try {
-			LOG.info("Sending " + a + " in state " + state.name() +
-					" with session ID " +
-					Arrays.hashCode(msg.getRaw(SESSION_ID)) + " in group " +
-					Arrays.hashCode(msg.getRaw(GROUP_ID)) + ". " +
-					"Moving on to state " +
-					getState(localState.getLong(STATE)).name()
-			);
-		} catch (FormatException e) {
-			if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
-		}
+		LOG.info("Sending " + a + " in state " + state.name() +
+				" with session ID " +
+				msg.getSessionId().hashCode() + " in group " +
+				msg.getGroupId().hashCode() + ". " +
+				"Moving on to state " + localState.getState().name()
+		);
 	}
 
-	private void logMessageReceived(InviteeProtocolState currentState,
-			InviteeProtocolState nextState, long type, BdfDictionary msg) {
+	private void logMessageReceived(State currentState, State nextState,
+			long type, BaseMessage msg) {
+
 		if (!LOG.isLoggable(INFO)) return;
 
-		try {
-			String t = "unknown";
-			if (type == SHARE_MSG_TYPE_INVITATION) t = "INVITE";
-			else if (type == SHARE_MSG_TYPE_LEAVE) t = "LEAVE";
-			else if (type == SHARE_MSG_TYPE_ABORT) t = "ABORT";
+		String t = "unknown";
+		if (type == SHARE_MSG_TYPE_INVITATION) t = "INVITE";
+		else if (type == SHARE_MSG_TYPE_LEAVE) t = "LEAVE";
+		else if (type == SHARE_MSG_TYPE_ABORT) t = "ABORT";
 
-			LOG.info("Received " + t + " in state " + currentState.name() +
-					" with session ID " +
-					Arrays.hashCode(msg.getRaw(SESSION_ID)) + " in group " +
-					Arrays.hashCode(msg.getRaw(GROUP_ID)) + ". " +
-					"Moving on to state " + nextState.name()
-			);
-		} catch (FormatException e) {
-			if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
-		}
+		LOG.info("Received " + t + " in state " + currentState.name() +
+				" with session ID " +
+				msg.getSessionId().hashCode() + " in group " +
+				msg.getGroupId().hashCode() + ". " +
+				"Moving on to state " + nextState.name()
+		);
 	}
 
 	@Override
-	public StateUpdate<BdfDictionary, BdfDictionary> onMessageDelivered(
-			BdfDictionary localState, BdfDictionary delivered) {
+	public StateUpdate<InviteeSessionState, BaseMessage> onMessageDelivered(
+			InviteeSessionState localState, BaseMessage delivered) {
 		try {
 			return noUpdate(localState, false);
 		} catch (FormatException e) {
@@ -228,38 +208,32 @@ public class InviteeEngine
 		}
 	}
 
-	private InviteeProtocolState getState(Long state) {
-		return InviteeProtocolState.fromValue(state.intValue());
-	}
-
-	private StateUpdate<BdfDictionary, BdfDictionary> abortSession(
-			InviteeProtocolState currentState, BdfDictionary localState)
+	private StateUpdate<InviteeSessionState, BaseMessage> abortSession(
+			State currentState, InviteeSessionState localState)
 			throws FormatException {
 
 		if (LOG.isLoggable(WARNING)) {
 			LOG.warning("Aborting protocol session " +
-					Arrays.hashCode(localState.getRaw(SESSION_ID)) +
+					localState.getSessionId().hashCode() +
 					" in state " + currentState.name());
 		}
-
-		localState.put(STATE, ERROR.getValue());
-		BdfDictionary msg = new BdfDictionary();
-		msg.put(TYPE, SHARE_MSG_TYPE_ABORT);
-		msg.put(SESSION_ID, localState.getRaw(SESSION_ID));
-		msg.put(GROUP_ID, localState.getRaw(GROUP_ID));
-		List<BdfDictionary> messages = Collections.singletonList(msg);
+		localState.setState(ERROR);
+		BaseMessage msg =
+				new SimpleMessage(SHARE_MSG_TYPE_ABORT, localState.getGroupId(),
+						localState.getSessionId());
+		List<BaseMessage> messages = Collections.singletonList(msg);
 
 		List<Event> events = Collections.emptyList();
 
-		return new StateUpdate<BdfDictionary, BdfDictionary>(false, false,
+		return new StateUpdate<InviteeSessionState, BaseMessage>(false, false,
 				localState, messages, events);
 	}
 
-	private StateUpdate<BdfDictionary, BdfDictionary> noUpdate(
-			BdfDictionary localState, boolean delete) throws FormatException {
+	private StateUpdate<InviteeSessionState, BaseMessage> noUpdate(
+			InviteeSessionState localState, boolean delete) throws FormatException {
 
-		return new StateUpdate<BdfDictionary, BdfDictionary>(delete, false,
-				localState, Collections.<BdfDictionary>emptyList(),
+		return new StateUpdate<InviteeSessionState, BaseMessage>(delete, false,
+				localState, Collections.<BaseMessage>emptyList(),
 				Collections.<Event>emptyList());
 	}
 }

briar-core/src/org/briarproject/forum/InviteeSessionState.java

@@ -0,0 +1,120 @@
+package org.briarproject.forum;
+
+import org.briarproject.api.clients.SessionId;
+import org.briarproject.api.contact.ContactId;
+import org.briarproject.api.data.BdfDictionary;
+import org.briarproject.api.sync.GroupId;
+import org.briarproject.api.sync.MessageId;
+
+import static org.briarproject.api.forum.ForumConstants.IS_SHARER;
+import static org.briarproject.api.forum.ForumConstants.SHARE_MSG_TYPE_ABORT;
+import static org.briarproject.api.forum.ForumConstants.SHARE_MSG_TYPE_INVITATION;
+import static org.briarproject.api.forum.ForumConstants.SHARE_MSG_TYPE_LEAVE;
+import static org.briarproject.api.forum.ForumConstants.STATE;
+import static org.briarproject.forum.InviteeSessionState.Action.LOCAL_ACCEPT;
+import static org.briarproject.forum.InviteeSessionState.Action.LOCAL_DECLINE;
+import static org.briarproject.forum.InviteeSessionState.Action.LOCAL_LEAVE;
+import static org.briarproject.forum.InviteeSessionState.Action.REMOTE_INVITATION;
+import static org.briarproject.forum.InviteeSessionState.Action.REMOTE_LEAVE;
+
+// This class is not thread-safe
+public class InviteeSessionState extends ForumSharingSessionState {
+
+	private State state;
+
+	public InviteeSessionState(SessionId sessionId, MessageId storageId,
+			GroupId groupId, State state, ContactId contactId, GroupId forumId,
+			String forumName, byte[] forumSalt) {
+
+		super(sessionId, storageId, groupId, contactId, forumId, forumName,
+				forumSalt);
+		this.state = state;
+	}
+
+	public BdfDictionary toBdfDictionary() {
+		BdfDictionary d = super.toBdfDictionary();
+		d.put(STATE, getState().getValue());
+		d.put(IS_SHARER, false);
+		return d;
+	}
+
+	public void setState(State state) {
+		this.state = state;
+	}
+
+	public State getState() {
+		return state;
+	}
+
+	public enum State {
+		ERROR(0),
+		AWAIT_INVITATION(1) {
+			@Override
+			public State next(Action a) {
+				if (a == REMOTE_INVITATION) return AWAIT_LOCAL_RESPONSE;
+				return ERROR;
+			}
+		},
+		AWAIT_LOCAL_RESPONSE(2) {
+			@Override
+			public State next(Action a) {
+				if (a == LOCAL_ACCEPT || a == LOCAL_DECLINE) return FINISHED;
+				if (a == REMOTE_LEAVE) return LEFT;
+				return ERROR;
+			}
+		},
+		FINISHED(3) {
+			@Override
+			public State next(Action a) {
+				if (a == LOCAL_LEAVE || a == REMOTE_LEAVE) return LEFT;
+				return FINISHED;
+			}
+		},
+		LEFT(4) {
+			@Override
+			public State next(Action a) {
+				if (a == LOCAL_LEAVE) return ERROR;
+				return LEFT;
+			}
+		};
+
+		private final int value;
+
+		State(int value) {
+			this.value = value;
+		}
+
+		public int getValue() {
+			return value;
+		}
+
+		public static State fromValue(int value) {
+			for (State s : values()) {
+				if (s.value == value) return s;
+			}
+			throw new IllegalArgumentException();
+		}
+
+		public State next(Action a) {
+			return this;
+		}
+	}
+
+	public enum Action {
+		LOCAL_ACCEPT,
+		LOCAL_DECLINE,
+		LOCAL_LEAVE,
+		LOCAL_ABORT,
+		REMOTE_INVITATION,
+		REMOTE_LEAVE,
+		REMOTE_ABORT;
+
+		public static Action getRemote(long type) {
+			if (type == SHARE_MSG_TYPE_INVITATION) return REMOTE_INVITATION;
+			if (type == SHARE_MSG_TYPE_LEAVE) return REMOTE_LEAVE;
+			if (type == SHARE_MSG_TYPE_ABORT) return REMOTE_ABORT;
+			return null;
+		}
+	}
+
+}

briar-core/src/org/briarproject/forum/SharerEngine.java

@@ -3,64 +3,52 @@ package org.briarproject.forum;
 import org.briarproject.api.FormatException;
 import org.briarproject.api.clients.ProtocolEngine;
 import org.briarproject.api.contact.ContactId;
-import org.briarproject.api.data.BdfDictionary;
 import org.briarproject.api.event.Event;
 import org.briarproject.api.event.ForumInvitationResponseReceivedEvent;
-import org.briarproject.api.forum.SharerAction;
-import org.briarproject.api.forum.SharerProtocolState;
 
-import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
 import java.util.logging.Logger;
 
 import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
-import static org.briarproject.api.forum.ForumConstants.CONTACT_ID;
-import static org.briarproject.api.forum.ForumConstants.FORUM_NAME;
-import static org.briarproject.api.forum.ForumConstants.FORUM_SALT;
-import static org.briarproject.api.forum.ForumConstants.GROUP_ID;
-import static org.briarproject.api.forum.ForumConstants.INVITATION_MSG;
-import static org.briarproject.api.forum.ForumConstants.SESSION_ID;
 import static org.briarproject.api.forum.ForumConstants.SHARE_MSG_TYPE_ABORT;
 import static org.briarproject.api.forum.ForumConstants.SHARE_MSG_TYPE_ACCEPT;
 import static org.briarproject.api.forum.ForumConstants.SHARE_MSG_TYPE_DECLINE;
-import static org.briarproject.api.forum.ForumConstants.SHARE_MSG_TYPE_INVITATION;
 import static org.briarproject.api.forum.ForumConstants.SHARE_MSG_TYPE_LEAVE;
-import static org.briarproject.api.forum.ForumConstants.STATE;
-import static org.briarproject.api.forum.ForumConstants.TASK;
 import static org.briarproject.api.forum.ForumConstants.TASK_ADD_FORUM_TO_LIST_TO_BE_SHARED_BY_US;
 import static org.briarproject.api.forum.ForumConstants.TASK_REMOVE_FORUM_FROM_LIST_TO_BE_SHARED_BY_US;
 import static org.briarproject.api.forum.ForumConstants.TASK_SHARE_FORUM;
 import static org.briarproject.api.forum.ForumConstants.TASK_UNSHARE_FORUM_SHARED_BY_US;
-import static org.briarproject.api.forum.ForumConstants.TYPE;
-import static org.briarproject.api.forum.SharerAction.LOCAL_ABORT;
-import static org.briarproject.api.forum.SharerAction.LOCAL_INVITATION;
-import static org.briarproject.api.forum.SharerAction.LOCAL_LEAVE;
-import static org.briarproject.api.forum.SharerAction.REMOTE_ACCEPT;
-import static org.briarproject.api.forum.SharerAction.REMOTE_DECLINE;
-import static org.briarproject.api.forum.SharerAction.REMOTE_LEAVE;
-import static org.briarproject.api.forum.SharerProtocolState.ERROR;
-import static org.briarproject.api.forum.SharerProtocolState.FINISHED;
-import static org.briarproject.api.forum.SharerProtocolState.LEFT;
+import static org.briarproject.api.forum.ForumSharingMessage.BaseMessage;
+import static org.briarproject.api.forum.ForumSharingMessage.Invitation;
+import static org.briarproject.api.forum.ForumSharingMessage.SimpleMessage;
+import static org.briarproject.forum.SharerSessionState.Action;
+import static org.briarproject.forum.SharerSessionState.Action.LOCAL_ABORT;
+import static org.briarproject.forum.SharerSessionState.Action.LOCAL_INVITATION;
+import static org.briarproject.forum.SharerSessionState.Action.LOCAL_LEAVE;
+import static org.briarproject.forum.SharerSessionState.Action.REMOTE_ACCEPT;
+import static org.briarproject.forum.SharerSessionState.Action.REMOTE_DECLINE;
+import static org.briarproject.forum.SharerSessionState.Action.REMOTE_LEAVE;
+import static org.briarproject.forum.SharerSessionState.State;
+import static org.briarproject.forum.SharerSessionState.State.ERROR;
+import static org.briarproject.forum.SharerSessionState.State.FINISHED;
+import static org.briarproject.forum.SharerSessionState.State.LEFT;
 
 public class SharerEngine
-		implements ProtocolEngine<BdfDictionary, BdfDictionary, BdfDictionary> {
+		implements ProtocolEngine<Action, SharerSessionState, BaseMessage> {
 
 	private static final Logger LOG =
 			Logger.getLogger(SharerEngine.class.getName());
 
 	@Override
-	public StateUpdate<BdfDictionary, BdfDictionary> onLocalAction(
-			BdfDictionary localState, BdfDictionary localAction) {
+	public StateUpdate<SharerSessionState, BaseMessage> onLocalAction(
+			SharerSessionState localState, Action action) {
 
 		try {
-			SharerProtocolState currentState =
-					getState(localState.getLong(STATE));
-			long type = localAction.getLong(TYPE);
-			SharerAction action = SharerAction.getLocal(type);
-			SharerProtocolState nextState = currentState.next(action);
-			localState.put(STATE, nextState.getValue());
+			State currentState = localState.getState();
+			State nextState = currentState.next(action);
+			localState.setState(nextState);
 
 			if (action == LOCAL_ABORT && currentState != ERROR) {
 				return abortSession(currentState, localState);
@@ -73,38 +61,29 @@ public class SharerEngine
 				}
 				return noUpdate(localState, true);
 			}
-			List<BdfDictionary> messages;
+			List<BaseMessage> messages;
 			List<Event> events = Collections.emptyList();
 
 			if (action == LOCAL_INVITATION) {
-				BdfDictionary msg = new BdfDictionary();
-				msg.put(TYPE, SHARE_MSG_TYPE_INVITATION);
-				msg.put(SESSION_ID, localState.getRaw(SESSION_ID));
-				msg.put(GROUP_ID, localState.getRaw(GROUP_ID));
-				msg.put(FORUM_NAME, localState.getString(FORUM_NAME));
-				msg.put(FORUM_SALT, localState.getRaw(FORUM_SALT));
-				if (localAction.containsKey(INVITATION_MSG)) {
-					msg.put(INVITATION_MSG,
-							localAction.getString(INVITATION_MSG));
-				}
+				BaseMessage msg = new Invitation(localState.getGroupId(),
+						localState.getSessionId(), localState.getForumName(),
+						localState.getForumSalt(), localState.getMessage());
 				messages = Collections.singletonList(msg);
-				logLocalAction(currentState, localState, msg);
+				logLocalAction(currentState, nextState, msg);
 
 				// remember that we offered to share this forum
-				localState.put(TASK, TASK_ADD_FORUM_TO_LIST_TO_BE_SHARED_BY_US);
+				localState.setTask(TASK_ADD_FORUM_TO_LIST_TO_BE_SHARED_BY_US);
 			}
 			else if (action == LOCAL_LEAVE) {
-				BdfDictionary msg = new BdfDictionary();
-				msg.put(TYPE, SHARE_MSG_TYPE_LEAVE);
-				msg.put(SESSION_ID, localState.getRaw(SESSION_ID));
-				msg.put(GROUP_ID, localState.getRaw(GROUP_ID));
+				BaseMessage msg = new SimpleMessage(SHARE_MSG_TYPE_LEAVE,
+						localState.getGroupId(), localState.getSessionId());
 				messages = Collections.singletonList(msg);
-				logLocalAction(currentState, localState, msg);
+				logLocalAction(currentState, nextState, msg);
 			}
 			else {
 				throw new IllegalArgumentException("Unknown Local Action");
 			}
-			return new StateUpdate<BdfDictionary, BdfDictionary>(false,
+			return new StateUpdate<SharerSessionState, BaseMessage>(false,
 					false, localState, messages, events);
 		} catch (FormatException e) {
 			throw new IllegalArgumentException(e);
@@ -112,18 +91,16 @@ public class SharerEngine
 	}
 
 	@Override
-	public StateUpdate<BdfDictionary, BdfDictionary> onMessageReceived(
-			BdfDictionary localState, BdfDictionary msg) {
+	public StateUpdate<SharerSessionState, BaseMessage> onMessageReceived(
+			SharerSessionState localState, BaseMessage msg) {
 
 		try {
-			SharerProtocolState currentState =
-					getState(localState.getLong(STATE));
-			long type = msg.getLong(TYPE);
-			SharerAction action = SharerAction.getRemote(type);
-			SharerProtocolState nextState = currentState.next(action);
-			localState.put(STATE, nextState.getValue());
+			State currentState = localState.getState();
+			Action action = Action.getRemote(msg.getType());
+			State nextState = currentState.next(action);
+			localState.setState(nextState);
 
-			logMessageReceived(currentState, nextState, type, msg);
+			logMessageReceived(currentState, nextState, msg.getType(), msg);
 
 			if (nextState == ERROR) {
 				if (currentState != ERROR) {
@@ -132,7 +109,7 @@ public class SharerEngine
 					return noUpdate(localState, true);
 				}
 			}
-			List<BdfDictionary> messages = Collections.emptyList();
+			List<BaseMessage> messages = Collections.emptyList();
 			List<Event> events = Collections.emptyList();
 			boolean deleteMsg = false;
 
@@ -141,7 +118,7 @@ public class SharerEngine
 				deleteMsg = true;
 			}
 			else if (action == REMOTE_LEAVE) {
-				localState.put(TASK, TASK_UNSHARE_FORUM_SHARED_BY_US);
+				localState.setTask(TASK_UNSHARE_FORUM_SHARED_BY_US);
 			}
 			else if (currentState == FINISHED) {
 				// ignore and delete messages coming in while in that state
@@ -151,74 +128,65 @@ public class SharerEngine
 			// we have sent our invitation and just got a response
 			else if (action == REMOTE_ACCEPT || action == REMOTE_DECLINE) {
 				if (action == REMOTE_ACCEPT) {
-					localState.put(TASK, TASK_SHARE_FORUM);
+					localState.setTask(TASK_SHARE_FORUM);
 				} else {
 					// this ensures that the forum can be shared again
-					localState.put(TASK,
+					localState.setTask(
 							TASK_REMOVE_FORUM_FROM_LIST_TO_BE_SHARED_BY_US);
 				}
-				String name = localState.getString(FORUM_NAME);
-				ContactId c = new ContactId(
-						localState.getLong(CONTACT_ID).intValue());
+				String name = localState.getForumName();
+				ContactId c = localState.getContactId();
 				Event event = new ForumInvitationResponseReceivedEvent(name, c);
 				events = Collections.singletonList(event);
 			}
 			else {
 				throw new IllegalArgumentException("Bad state");
 			}
-			return new StateUpdate<BdfDictionary, BdfDictionary>(deleteMsg,
+			return new StateUpdate<SharerSessionState, BaseMessage>(deleteMsg,
 					false, localState, messages, events);
 		} catch (FormatException e) {
 			throw new IllegalArgumentException(e);
 		}
 	}
 
-	private void logLocalAction(SharerProtocolState state,
-			BdfDictionary localState, BdfDictionary msg) {
+	private void logLocalAction(State currentState, State nextState,
+			BaseMessage msg) {
 
 		if (!LOG.isLoggable(INFO)) return;
 
 		String a = "invitation";
-		if (msg.getLong(TYPE, -1L) == SHARE_MSG_TYPE_LEAVE) a = "leave";
+		if (msg.getType() == SHARE_MSG_TYPE_LEAVE) a = "leave";
 
-		try {
-			LOG.info("Sending " + a + " in state " + state.name() +
-					" with session ID " +
-					Arrays.hashCode(msg.getRaw(SESSION_ID)) + " in group " +
-					Arrays.hashCode(msg.getRaw(GROUP_ID)) + ". " +
-					"Moving on to state " +
-					getState(localState.getLong(STATE)).name()
-			);
-		} catch (FormatException e) {
-			if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
-		}
+		LOG.info("Sending " + a + " in state " + currentState.name() +
+				" with session ID " +
+				msg.getSessionId().hashCode() + " in group " +
+				msg.getGroupId().hashCode() + ". " +
+				"Moving on to state " + nextState.name()
+		);
 	}
 
-	private void logMessageReceived(SharerProtocolState currentState,
-			SharerProtocolState nextState, long type, BdfDictionary msg) {
+	private void logMessageReceived(State currentState, State nextState,
+			long type, BaseMessage msg) {
+
 		if (!LOG.isLoggable(INFO)) return;
 
-		try {
-			String t = "unknown";
-			if (type == SHARE_MSG_TYPE_ACCEPT) t = "ACCEPT";
-			else if (type == SHARE_MSG_TYPE_DECLINE) t = "DECLINE";
-			else if (type == SHARE_MSG_TYPE_LEAVE) t = "LEAVE";
-			else if (type == SHARE_MSG_TYPE_ABORT) t = "ABORT";
+		String t = "unknown";
+		if (type == SHARE_MSG_TYPE_ACCEPT) t = "ACCEPT";
+		else if (type == SHARE_MSG_TYPE_DECLINE) t = "DECLINE";
+		else if (type == SHARE_MSG_TYPE_LEAVE) t = "LEAVE";
+		else if (type == SHARE_MSG_TYPE_ABORT) t = "ABORT";
 
-			LOG.info("Received " + t + " in state " + currentState.name() +
-					" with session ID " +
-					Arrays.hashCode(msg.getRaw(SESSION_ID)) + " in group " +
-					Arrays.hashCode(msg.getRaw(GROUP_ID)) + ". " +
-					"Moving on to state " + nextState.name()
-			);
-		} catch (FormatException e) {
-			if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
-		}
+		LOG.info("Received " + t + " in state " + currentState.name() +
+				" with session ID " +
+				msg.getSessionId().hashCode() + " in group " +
+				msg.getGroupId().hashCode() + ". " +
+				"Moving on to state " + nextState.name()
+		);
 	}
 
 	@Override
-	public StateUpdate<BdfDictionary, BdfDictionary> onMessageDelivered(
-			BdfDictionary localState, BdfDictionary delivered) {
+	public StateUpdate<SharerSessionState, BaseMessage> onMessageDelivered(
+			SharerSessionState localState, BaseMessage delivered) {
 		try {
 			return noUpdate(localState, false);
 		} catch (FormatException e) {
@@ -227,38 +195,34 @@ public class SharerEngine
 		}
 	}
 
-	private SharerProtocolState getState(Long state) {
-		 return SharerProtocolState.fromValue(state.intValue());
-	}
-
-	private StateUpdate<BdfDictionary, BdfDictionary> abortSession(
-			SharerProtocolState currentState, BdfDictionary localState)
+	private StateUpdate<SharerSessionState, BaseMessage> abortSession(
+			State currentState, SharerSessionState localState)
 			throws FormatException {
 
 		if (LOG.isLoggable(WARNING)) {
 			LOG.warning("Aborting protocol session " +
-					Arrays.hashCode(localState.getRaw(SESSION_ID)) +
+					localState.getSessionId().hashCode() +
 					" in state " + currentState.name());
 		}
 
-		localState.put(STATE, ERROR.getValue());
-		BdfDictionary msg = new BdfDictionary();
-		msg.put(TYPE, SHARE_MSG_TYPE_ABORT);
-		msg.put(SESSION_ID, localState.getRaw(SESSION_ID));
-		msg.put(GROUP_ID, localState.getRaw(GROUP_ID));
-		List<BdfDictionary> messages = Collections.singletonList(msg);
+		localState.setState(ERROR);
+		BaseMessage msg = new SimpleMessage(SHARE_MSG_TYPE_ABORT,
+				localState.getGroupId(), localState.getSessionId());
+		List<BaseMessage> messages = Collections.singletonList(msg);
 
 		List<Event> events = Collections.emptyList();
 
-		return new StateUpdate<BdfDictionary, BdfDictionary>(false, false,
+		return new StateUpdate<SharerSessionState, BaseMessage>(false, false,
 				localState, messages, events);
 	}
 
-	private StateUpdate<BdfDictionary, BdfDictionary> noUpdate(
-			BdfDictionary localState, boolean delete) throws FormatException {
+	private StateUpdate<SharerSessionState, BaseMessage> noUpdate(
+			SharerSessionState localState, boolean delete)
+			throws FormatException {
 
-		return new StateUpdate<BdfDictionary, BdfDictionary>(delete, false,
-				localState, Collections.<BdfDictionary>emptyList(),
+		return new StateUpdate<SharerSessionState, BaseMessage>(delete, false,
+				localState, Collections.<BaseMessage>emptyList(),
 				Collections.<Event>emptyList());
 	}
+
 }

briar-core/src/org/briarproject/forum/SharerSessionState.java

@@ -0,0 +1,131 @@
+package org.briarproject.forum;
+
+import org.briarproject.api.clients.SessionId;
+import org.briarproject.api.contact.ContactId;
+import org.briarproject.api.data.BdfDictionary;
+import org.briarproject.api.sync.GroupId;
+import org.briarproject.api.sync.MessageId;
+
+import static org.briarproject.api.forum.ForumConstants.IS_SHARER;
+import static org.briarproject.api.forum.ForumConstants.SHARE_MSG_TYPE_ABORT;
+import static org.briarproject.api.forum.ForumConstants.SHARE_MSG_TYPE_ACCEPT;
+import static org.briarproject.api.forum.ForumConstants.SHARE_MSG_TYPE_DECLINE;
+import static org.briarproject.api.forum.ForumConstants.SHARE_MSG_TYPE_LEAVE;
+import static org.briarproject.api.forum.ForumConstants.STATE;
+import static org.briarproject.forum.SharerSessionState.Action.LOCAL_INVITATION;
+import static org.briarproject.forum.SharerSessionState.Action.LOCAL_LEAVE;
+import static org.briarproject.forum.SharerSessionState.Action.REMOTE_ACCEPT;
+import static org.briarproject.forum.SharerSessionState.Action.REMOTE_DECLINE;
+import static org.briarproject.forum.SharerSessionState.Action.REMOTE_LEAVE;
+
+// This class is not thread-safe
+public class SharerSessionState extends ForumSharingSessionState {
+
+	private State state;
+	private String msg = null;
+
+	public SharerSessionState(SessionId sessionId, MessageId storageId,
+			GroupId groupId, State state, ContactId contactId, GroupId forumId,
+			String forumName, byte[] forumSalt) {
+
+		super(sessionId, storageId, groupId, contactId, forumId, forumName,
+				forumSalt);
+		this.state = state;
+	}
+
+	public BdfDictionary toBdfDictionary() {
+		BdfDictionary d = super.toBdfDictionary();
+		d.put(STATE, getState().getValue());
+		d.put(IS_SHARER, true);
+		return d;
+	}
+
+	public void setState(State state) {
+		this.state = state;
+	}
+
+	public State getState() {
+		return state;
+	}
+
+	public void setMessage(String msg) {
+		this.msg = msg;
+	}
+
+	public String getMessage() {
+		return this.msg;
+	}
+
+	public enum State {
+		ERROR(0),
+		PREPARE_INVITATION(1) {
+			@Override
+			public State next(Action a) {
+				if (a == LOCAL_INVITATION) return AWAIT_RESPONSE;
+				return ERROR;
+			}
+		},
+		AWAIT_RESPONSE(2) {
+			@Override
+			public State next(Action a) {
+				if (a == REMOTE_ACCEPT || a == REMOTE_DECLINE) return FINISHED;
+				if (a == LOCAL_LEAVE) return LEFT;
+				return ERROR;
+			}
+		},
+		FINISHED(3) {
+			@Override
+			public State next(Action a) {
+				if (a == LOCAL_LEAVE || a == REMOTE_LEAVE) return LEFT;
+				return FINISHED;
+			}
+		},
+		LEFT(4) {
+			@Override
+			public State next(Action a) {
+				if (a == LOCAL_LEAVE) return ERROR;
+				return LEFT;
+			}
+		};
+
+		private final int value;
+
+		State(int value) {
+			this.value = value;
+		}
+
+		public int getValue() {
+			return value;
+		}
+
+		public static State fromValue(int value) {
+			for (State s : values()) {
+				if (s.value == value) return s;
+			}
+			throw new IllegalArgumentException();
+		}
+
+		public State next(Action a) {
+			return this;
+		}
+	}
+
+	public enum Action {
+		LOCAL_INVITATION,
+		LOCAL_LEAVE,
+		LOCAL_ABORT,
+		REMOTE_ACCEPT,
+		REMOTE_DECLINE,
+		REMOTE_LEAVE,
+		REMOTE_ABORT;
+
+		public static Action getRemote(long type) {
+			if (type == SHARE_MSG_TYPE_ACCEPT) return REMOTE_ACCEPT;
+			if (type == SHARE_MSG_TYPE_DECLINE) return REMOTE_DECLINE;
+			if (type == SHARE_MSG_TYPE_LEAVE) return REMOTE_LEAVE;
+			if (type == SHARE_MSG_TYPE_ABORT) return REMOTE_ABORT;
+			return null;
+		}
+	}
+
+}

briar-core/src/org/briarproject/introduction/IntroductionManagerImpl.java

@@ -9,10 +9,12 @@ import org.briarproject.api.contact.ContactId;
 import org.briarproject.api.contact.ContactManager.AddContactHook;
 import org.briarproject.api.contact.ContactManager.RemoveContactHook;
 import org.briarproject.api.data.BdfDictionary;
+import org.briarproject.api.data.BdfEntry;
 import org.briarproject.api.data.BdfList;
 import org.briarproject.api.data.MetadataParser;
 import org.briarproject.api.db.DatabaseComponent;
 import org.briarproject.api.db.DbException;
+import org.briarproject.api.db.NoSuchContactException;
 import org.briarproject.api.db.NoSuchMessageException;
 import org.briarproject.api.db.Transaction;
 import org.briarproject.api.identity.AuthorId;
@@ -136,29 +138,58 @@ class IntroductionManagerImpl extends BdfIncomingMessageHook
 
 	@Override
 	public void removingContact(Transaction txn, Contact c) throws DbException {
-		// check for open sessions with that contact and abort those
-		Long id = (long) c.getId().getInt();
+		GroupId gId = introductionGroupFactory.createLocalGroup().getId();
+
+		// search for session states where c introduced us
+		BdfDictionary query = BdfDictionary.of(
+				new BdfEntry(ROLE, ROLE_INTRODUCEE),
+				new BdfEntry(CONTACT_ID_1, c.getId().getInt())
+		);
 		try {
 			Map<MessageId, BdfDictionary> map = clientHelper
-					.getMessageMetadataAsDictionary(txn,
-							introductionGroupFactory.createLocalGroup().getId());
+					.getMessageMetadataAsDictionary(txn, gId, query);
+			for (Map.Entry<MessageId, BdfDictionary> entry : map.entrySet()) {
+				// delete states if introducee removes introducer
+				deleteMessage(txn, entry.getKey());
+			}
+		} catch (FormatException e) {
+			if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
+		}
+
+		// check for open sessions with c and abort those,
+		// so the other introducee knows
+		query = BdfDictionary.of(
+				new BdfEntry(ROLE, ROLE_INTRODUCER)
+		);
+		try {
+			Map<MessageId, BdfDictionary> map = clientHelper
+					.getMessageMetadataAsDictionary(txn, gId, query);
 			for (Map.Entry<MessageId, BdfDictionary> entry : map.entrySet()) {
 				BdfDictionary d = entry.getValue();
-				long role = d.getLong(ROLE, -1L);
-				if (role != ROLE_INTRODUCER) {
-					if (d.getLong(CONTACT_ID_1).equals(id)) {
-						// delete states if introducee removes introducer
-						deleteMessage(txn, entry.getKey());
-					}
-				}
-				else if (d.getLong(CONTACT_ID_1).equals(id) ||
-						d.getLong(CONTACT_ID_2).equals(id)) {
+				ContactId c1 = new ContactId(d.getLong(CONTACT_ID_1).intValue());
+				ContactId c2 = new ContactId(d.getLong(CONTACT_ID_2).intValue());
 
+				if (c1.equals(c.getId()) || c2.equals(c.getId())) {
 					IntroducerProtocolState state = IntroducerProtocolState
 							.fromValue(d.getLong(STATE).intValue());
+					// abort protocol if still ongoing
 					if (IntroducerProtocolState.isOngoing(state)) {
 						introducerManager.abort(txn, d);
 					}
+					// also delete state if both contacts have been deleted
+					if (c1.equals(c.getId())) {
+						try {
+							db.getContact(txn, c2);
+						} catch (NoSuchContactException e) {
+							deleteMessage(txn, entry.getKey());
+						}
+					} else if (c2.equals(c.getId())) {
+						try {
+							db.getContact(txn, c1);
+						} catch (NoSuchContactException e) {
+							deleteMessage(txn, entry.getKey());
+						}
+					}
 				}
 			}
 		} catch (FormatException e) {

briar-core/src/org/briarproject/introduction/IntroductionValidator.java

@@ -2,10 +2,11 @@ package org.briarproject.introduction;
 
 import org.briarproject.api.FormatException;
 import org.briarproject.api.clients.ClientHelper;
+import org.briarproject.api.clients.SessionId;
+import org.briarproject.api.clients.BdfMessageContext;
 import org.briarproject.api.data.BdfDictionary;
 import org.briarproject.api.data.BdfList;
 import org.briarproject.api.data.MetadataEncoder;
-import org.briarproject.api.clients.SessionId;
 import org.briarproject.api.sync.Group;
 import org.briarproject.api.sync.Message;
 import org.briarproject.api.system.Clock;
@@ -42,7 +43,7 @@ class IntroductionValidator extends BdfMessageValidator {
 	}
 
 	@Override
-	protected BdfDictionary validateMessage(Message m, Group g, BdfList body)
+	protected BdfMessageContext validateMessage(Message m, Group g, BdfList body)
 			throws FormatException {
 
 		BdfDictionary d;
@@ -67,7 +68,7 @@ class IntroductionValidator extends BdfMessageValidator {
 		d.put(GROUP_ID, m.getGroupId());
 		d.put(MESSAGE_ID, m.getId());
 		d.put(MESSAGE_TIME, m.getTimestamp());
-		return d;
+		return new BdfMessageContext(d);
 	}
 
 	private BdfDictionary validateRequest(BdfList message)

briar-core/src/org/briarproject/messaging/PrivateMessageValidator.java

@@ -3,6 +3,7 @@ package org.briarproject.messaging;
 import org.briarproject.api.FormatException;
 import org.briarproject.api.UniqueId;
 import org.briarproject.api.clients.ClientHelper;
+import org.briarproject.api.clients.BdfMessageContext;
 import org.briarproject.api.data.BdfDictionary;
 import org.briarproject.api.data.BdfList;
 import org.briarproject.api.data.MetadataEncoder;
@@ -22,7 +23,7 @@ class PrivateMessageValidator extends BdfMessageValidator {
 	}
 
 	@Override
-	protected BdfDictionary validateMessage(Message m, Group g,
+	protected BdfMessageContext validateMessage(Message m, Group g,
 			BdfList body) throws FormatException {
 		// Parent ID, content type, private message body
 		checkSize(body, 3);
@@ -42,6 +43,6 @@ class PrivateMessageValidator extends BdfMessageValidator {
 		meta.put("contentType", contentType);
 		meta.put("local", false);
 		meta.put("read", false);
-		return meta;
+		return new BdfMessageContext(meta);
 	}
 }

briar-core/src/org/briarproject/properties/TransportPropertyValidator.java

@@ -2,6 +2,7 @@ package org.briarproject.properties;
 
 import org.briarproject.api.FormatException;
 import org.briarproject.api.clients.ClientHelper;
+import org.briarproject.api.clients.BdfMessageContext;
 import org.briarproject.api.data.BdfDictionary;
 import org.briarproject.api.data.BdfList;
 import org.briarproject.api.data.MetadataEncoder;
@@ -22,7 +23,7 @@ public class TransportPropertyValidator extends BdfMessageValidator {
 	}
 
 	@Override
-	protected BdfDictionary validateMessage(Message m, Group g,
+	protected BdfMessageContext validateMessage(Message m, Group g,
 			BdfList body) throws FormatException {
 		// Transport ID, version, properties
 		checkSize(body, 3);
@@ -45,6 +46,6 @@ public class TransportPropertyValidator extends BdfMessageValidator {
 		meta.put("transportId", transportId);
 		meta.put("version", version);
 		meta.put("local", false);
-		return meta;
+		return new BdfMessageContext(meta);
 	}
 }

briar-core/src/org/briarproject/sync/ValidationManagerImpl.java

@@ -16,9 +16,11 @@ import org.briarproject.api.lifecycle.Service;
 import org.briarproject.api.sync.ClientId;
 import org.briarproject.api.sync.Group;
 import org.briarproject.api.sync.GroupId;
+import org.briarproject.api.sync.InvalidMessageException;
 import org.briarproject.api.sync.Message;
 import org.briarproject.api.sync.MessageId;
 import org.briarproject.api.sync.ValidationManager;
+import org.briarproject.api.sync.MessageContext;
 import org.briarproject.util.ByteUtils;
 
 import java.util.LinkedList;
@@ -31,6 +33,7 @@ import java.util.logging.Logger;
 
 import javax.inject.Inject;
 
+import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
 import static org.briarproject.api.sync.SyncConstants.MESSAGE_HEADER_LENGTH;
 
@@ -152,31 +155,54 @@ class ValidationManagerImpl implements ValidationManager, Service,
 				if (v == null) {
 					LOG.warning("No validator");
 				} else {
-					Metadata meta = v.validateMessage(m, g);
-					storeValidationResult(m, g.getClientId(), meta);
+					try {
+						MessageContext context = v.validateMessage(m, g);
+						storeMessageContext(m, g.getClientId(), context);
+					} catch (InvalidMessageException e) {
+						if (LOG.isLoggable(INFO))
+							LOG.log(INFO, e.toString(), e);
+						markMessageInvalid(m, g.getClientId());
+					}
 				}
 			}
 		});
 	}
 
-	private void storeValidationResult(final Message m, final ClientId c,
-			final Metadata meta) {
+	private void storeMessageContext(final Message m, final ClientId c,
+			final MessageContext result) {
 		dbExecutor.execute(new Runnable() {
 			@Override
 			public void run() {
 				try {
 					Transaction txn = db.startTransaction(false);
 					try {
-						if (meta == null) {
-							db.setMessageValid(txn, m, c, false);
-						} else {
-							db.mergeMessageMetadata(txn, m.getId(), meta);
-							db.setMessageValid(txn, m, c, true);
-							db.setMessageShared(txn, m, true);
-							IncomingMessageHook hook = hooks.get(c);
-							if (hook != null)
-								hook.incomingMessage(txn, m, meta);
-						}
+						Metadata meta = result.getMetadata();
+						db.mergeMessageMetadata(txn, m.getId(), meta);
+						db.setMessageValid(txn, m, c, true);
+						db.setMessageShared(txn, m, true);
+						IncomingMessageHook hook = hooks.get(c);
+						if (hook != null)
+							hook.incomingMessage(txn, m, meta);
+						txn.setComplete();
+					} finally {
+						db.endTransaction(txn);
+					}
+				} catch (DbException e) {
+					if (LOG.isLoggable(WARNING))
+						LOG.log(WARNING, e.toString(), e);
+				}
+			}
+		});
+	}
+
+	private void markMessageInvalid(final Message m, final ClientId c) {
+		dbExecutor.execute(new Runnable() {
+			@Override
+			public void run() {
+				try {
+					Transaction txn = db.startTransaction(false);
+					try {
+						db.setMessageValid(txn, m, c, false);
 						txn.setComplete();
 					} finally {
 						db.endTransaction(txn);

briar-desktop/build.gradle

@@ -4,10 +4,6 @@ targetCompatibility = 1.7
 
 apply plugin: 'witness'
 
-repositories {
-	jcenter()
-}
-
 dependencies {
 	compile project(':briar-api')
 	compile fileTree(dir: '../briar-core/libs', include: '*.jar')

briar-tests/build.gradle

@@ -4,10 +4,6 @@ targetCompatibility = 1.7
 
 apply plugin: 'witness'
 
-repositories {
-	jcenter()
-}
-
 dependencies {
 	compile project(':briar-api')
 	compile project(':briar-core')

briar-tests/src/org/briarproject/clients/MessageQueueManagerImplTest.java

@@ -20,6 +20,7 @@ import org.briarproject.api.sync.MessageId;
 import org.briarproject.api.sync.ValidationManager;
 import org.briarproject.api.sync.ValidationManager.IncomingMessageHook;
 import org.briarproject.api.sync.ValidationManager.MessageValidator;
+import org.briarproject.api.sync.MessageContext;
 import org.briarproject.util.ByteUtils;
 import org.hamcrest.Description;
 import org.jmock.Expectations;
@@ -210,7 +211,9 @@ public class MessageQueueManagerImplTest extends BriarTestCase {
 				new AtomicReference<MessageValidator>();
 		final QueueMessageValidator queueMessageValidator =
 				context.mock(QueueMessageValidator.class);
-		final Metadata messageMetadata = new Metadata();
+		final Metadata metadata = new Metadata();
+		final MessageContext messageContext =
+				new MessageContext(metadata);
 		// The message is valid, with a queue position of zero
 		final MessageId messageId = new MessageId(TestUtils.getRandomId());
 		final byte[] raw = new byte[QUEUE_MESSAGE_HEADER_LENGTH];
@@ -224,7 +227,7 @@ public class MessageQueueManagerImplTest extends BriarTestCase {
 			// The message should be delegated
 			oneOf(queueMessageValidator).validateMessage(
 					with(any(QueueMessage.class)), with(group));
-			will(returnValue(messageMetadata));
+			will(returnValue(messageContext));
 		}});
 
 		MessageQueueManagerImpl mqm = new MessageQueueManagerImpl(db,
@@ -235,7 +238,8 @@ public class MessageQueueManagerImplTest extends BriarTestCase {
 		MessageValidator delegate = captured.get();
 		assertNotNull(delegate);
 		// The message should be valid and the metadata should be returned
-		assertSame(messageMetadata, delegate.validateMessage(message, group));
+		assertSame(messageContext, delegate.validateMessage(message, group));
+		assertSame(metadata, messageContext.getMetadata());
 
 		context.assertIsSatisfied();
 	}

briar-tests/src/org/briarproject/introduction/IntroductionValidatorTest.java

@@ -85,7 +85,8 @@ public class IntroductionValidatorTest extends BriarTestCase {
 				name, publicKey, text);
 
 		final BdfDictionary result =
-				validator.validateMessage(message, group, body);
+				validator.validateMessage(message, group, body)
+						.getDictionary();
 
 		assertEquals(Long.valueOf(TYPE_REQUEST), result.getLong(TYPE));
 		assertEquals(sessionId, result.getRaw(SESSION_ID));
@@ -182,7 +183,7 @@ public class IntroductionValidatorTest extends BriarTestCase {
 				msg.getRaw(E_PUBLIC_KEY), msg.getDictionary(TRANSPORT));
 
 		final BdfDictionary result =
-				validator.validateMessage(message, group, body);
+				validator.validateMessage(message, group, body).getDictionary();
 
 		assertEquals(Long.valueOf(TYPE_RESPONSE), result.getLong(TYPE));
 		assertEquals(sessionId, result.getRaw(SESSION_ID));
@@ -199,7 +200,8 @@ public class IntroductionValidatorTest extends BriarTestCase {
 		BdfList body = BdfList.of(msg.getLong(TYPE), msg.getRaw(SESSION_ID),
 				msg.getBoolean(ACCEPT));
 
-		BdfDictionary result = validator.validateMessage(message, group, body);
+		BdfDictionary result = validator.validateMessage(message, group, body)
+				.getDictionary();
 
 		assertFalse(result.getBoolean(ACCEPT));
 		context.assertIsSatisfied();
@@ -288,7 +290,7 @@ public class IntroductionValidatorTest extends BriarTestCase {
 		BdfList body = BdfList.of(msg.getLong(TYPE), msg.getRaw(SESSION_ID));
 
 		BdfDictionary result =
-				validator.validateMessage(message, group, body);
+				validator.validateMessage(message, group, body).getDictionary();
 
 		assertEquals(Long.valueOf(TYPE_ACK), result.getLong(TYPE));
 		assertEquals(sessionId, result.getRaw(SESSION_ID));
@@ -334,7 +336,7 @@ public class IntroductionValidatorTest extends BriarTestCase {
 		BdfList body = BdfList.of(msg.getLong(TYPE), msg.getRaw(SESSION_ID));
 
 		BdfDictionary result =
-				validator.validateMessage(message, group, body);
+				validator.validateMessage(message, group, body).getDictionary();
 
 		assertEquals(Long.valueOf(TYPE_ABORT), result.getLong(TYPE));
 		assertEquals(sessionId, result.getRaw(SESSION_ID));

briar-tests/src/org/briarproject/properties/TransportPropertyValidatorTest.java

@@ -59,7 +59,8 @@ public class TransportPropertyValidatorTest extends BriarTestCase {
 
 		BdfList body = BdfList.of(transportId.getString(), 4, bdfDictionary);
 
-		BdfDictionary result = tpv.validateMessage(message, group, body);
+		BdfDictionary result = tpv.validateMessage(message, group, body)
+				.getDictionary();
 
 		assertEquals("test", result.getString("transportId"));
 		assertEquals(4, result.getLong("version").longValue());

briar-tests/src/org/briarproject/sync/ValidationManagerImplTest.java

@@ -14,10 +14,12 @@ import org.briarproject.api.event.MessageAddedEvent;
 import org.briarproject.api.sync.ClientId;
 import org.briarproject.api.sync.Group;
 import org.briarproject.api.sync.GroupId;
+import org.briarproject.api.sync.InvalidMessageException;
 import org.briarproject.api.sync.Message;
 import org.briarproject.api.sync.MessageId;
 import org.briarproject.api.sync.ValidationManager.IncomingMessageHook;
 import org.briarproject.api.sync.ValidationManager.MessageValidator;
+import org.briarproject.api.sync.MessageContext;
 import org.briarproject.util.ByteUtils;
 import org.jmock.Expectations;
 import org.jmock.Mockery;
@@ -41,6 +43,7 @@ public class ValidationManagerImplTest extends BriarTestCase {
 	private final Message message1 = new Message(messageId1, groupId, timestamp,
 			raw);
 	private final Metadata metadata = new Metadata();
+	final MessageContext validResult = new MessageContext(metadata);
 	private final ContactId contactId = new ContactId(234);
 
 	public ValidationManagerImplTest() {
@@ -80,7 +83,7 @@ public class ValidationManagerImplTest extends BriarTestCase {
 			oneOf(db).endTransaction(txn1);
 			// Validate the first message: valid
 			oneOf(validator).validateMessage(message, group);
-			will(returnValue(metadata));
+			will(returnValue(validResult));
 			// Store the validation result for the first message
 			oneOf(db).startTransaction(false);
 			will(returnValue(txn2));
@@ -100,7 +103,7 @@ public class ValidationManagerImplTest extends BriarTestCase {
 			oneOf(db).endTransaction(txn3);
 			// Validate the second message: invalid
 			oneOf(validator).validateMessage(message1, group);
-			will(returnValue(null));
+			will(throwException(new InvalidMessageException()));
 			// Store the validation result for the second message
 			oneOf(db).startTransaction(false);
 			will(returnValue(txn4));
@@ -154,7 +157,7 @@ public class ValidationManagerImplTest extends BriarTestCase {
 			oneOf(db).endTransaction(txn2);
 			// Validate the second message: invalid
 			oneOf(validator).validateMessage(message1, group);
-			will(returnValue(null));
+			will(throwException(new InvalidMessageException()));
 			// Store the validation result for the second message
 			oneOf(db).startTransaction(false);
 			will(returnValue(txn3));
@@ -211,7 +214,7 @@ public class ValidationManagerImplTest extends BriarTestCase {
 			oneOf(db).endTransaction(txn2);
 			// Validate the second message: invalid
 			oneOf(validator).validateMessage(message1, group);
-			will(returnValue(null));
+			will(throwException(new InvalidMessageException()));
 			// Store the validation result for the second message
 			oneOf(db).startTransaction(false);
 			will(returnValue(txn3));
@@ -248,7 +251,7 @@ public class ValidationManagerImplTest extends BriarTestCase {
 			oneOf(db).endTransaction(txn);
 			// Validate the message: valid
 			oneOf(validator).validateMessage(message, group);
-			will(returnValue(metadata));
+			will(returnValue(validResult));
 			// Store the validation result
 			oneOf(db).startTransaction(false);
 			will(returnValue(txn1));

build.gradle

@@ -1,11 +1,16 @@
 // Top-level build file where you can add configuration options common to all sub-projects/modules.
+
+allprojects {
+	repositories {
+		jcenter()
+		mavenLocal()
+	}
+}
+
 buildscript {
 	repositories {
-		mavenCentral()
-		maven {
-			url "https://plugins.gradle.org/m2/"
-		}
 		jcenter()
+		mavenLocal()
 	}
 
 	dependencies {
@@ -14,4 +19,4 @@ buildscript {
 		classpath 'de.undercouch:gradle-download-task:2.1.0'
 		classpath files('briar-core/libs/gradle-witness.jar')
 	}
-}
+}

gradle/wrapper/gradle-wrapper.properties

@@ -1,6 +1,6 @@
-#Wed Apr 27 17:31:51 BST 2016
+#Thu May 12 13:08:34 BST 2016
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-2.10-all.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-2.13-all.zip