Merge branch '322-forum-sharing-client' into 'master'

Forum Sharing Client Backend

This MR replaces the old `ForumSharingManagerImpl` with a new one
which is based on state machines and the `ProtocolEngine`.

There is a `SharerEngine` and a `InviteeEngine` that take care of state
transitions, messages, events and trigger actions to be carried out by
the `ForumSharingManagerImpl`. This is all very similar to the
Introduction Client.

The general sharing paradigm has been changed from sharing as a state to
sharing as an action. Now the UI can allow users to invite contacts to
forums. The contacts can accept or decline the invitation. Also, the
Forum Sharing Manager is notified when users leave a forum.

Please note that you will need the UI to actually test this. It is coming up soon in another MR.

Closes #322

See merge request !170

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

@@ -8,7 +8,7 @@ abstract class ConversationIntroductionItem extends ConversationItem {
 	private boolean answered;
 
 	public ConversationIntroductionItem(IntroductionRequest ir) {
-		super(ir.getMessageId(), ir.getTime());
+		super(ir.getMessageId(), ir.getTimestamp());
 
 		this.ir = ir;
 		this.answered = ir.wasAnswered();

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

@@ -69,7 +69,7 @@ public abstract class ConversationItem {
 						ir.getName());
 			}
 			return new ConversationNoticeOutItem(ir.getMessageId(), text,
-					ir.getTime(), ir.isSent(), ir.isSeen());
+					ir.getTimestamp(), ir.isSent(), ir.isSeen());
 		} else {
 			String text;
 			if (ir.wasAccepted()) {
@@ -88,7 +88,7 @@ public abstract class ConversationItem {
 				}
 			}
 			return new ConversationNoticeInItem(ir.getMessageId(), text,
-					ir.getTime(), ir.isRead());
+					ir.getTimestamp(), ir.isRead());
 		}
 	}
 
@@ -98,9 +98,9 @@ public abstract class ConversationItem {
 	public static ConversationItem from(IntroductionMessage im) {
 		if (im.isLocal())
 			return new ConversationNoticeOutItem(im.getMessageId(), "",
-					im.getTime(), false, false);
-		return new ConversationNoticeInItem(im.getMessageId(), "", im.getTime(),
-				im.isRead());
+					im.getTimestamp(), false, false);
+		return new ConversationNoticeInItem(im.getMessageId(), "",
+				im.getTimestamp(), im.isRead());
 	}
 
 	protected interface OutgoingItem {

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

@@ -171,7 +171,6 @@ implements EventListener, OnItemClickListener {
 			public void run() {
 				try {
 					forumManager.addForum(f);
-					forumSharingManager.setSharedWith(f.getId(), shared);
 				} catch (DbException e) {
 					if (LOG.isLoggable(WARNING))
 						LOG.log(WARNING, e.toString(), e);

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

@@ -91,7 +91,6 @@ public class ShareForumActivity extends BriarActivity implements
 				onBackPressed();
 				return true;
 			case R.id.action_share_forum:
-				storeVisibility();
 				return true;
 			default:
 				return super.onOptionsItemSelected(item);
@@ -140,26 +139,6 @@ public class ShareForumActivity extends BriarActivity implements
 		});
 	}
 
-	private void storeVisibility() {
-		runOnDbThread(new Runnable() {
-			public void run() {
-				try {
-					long now = System.currentTimeMillis();
-					Collection<ContactId> selected =
-							adapter.getSelectedContactIds();
-					forumSharingManager.setSharedWith(groupId, selected);
-					long duration = System.currentTimeMillis() - now;
-					if (LOG.isLoggable(INFO))
-						LOG.info("Update took " + duration + " ms");
-				} catch (DbException e) {
-					if (LOG.isLoggable(WARNING))
-						LOG.log(WARNING, e.toString(), e);
-				}
-				finishOnUiThread();
-			}
-		});
-	}
-
 	@Override
 	public void onItemClick(View view, ContactListItem item) {
 		((SelectableContactListItem) item).toggleSelected();

briar-api/src/org/briarproject/api/event/ForumInvitationReceivedEvent.java

@@ -0,0 +1,24 @@
+package org.briarproject.api.event;
+
+import org.briarproject.api.contact.ContactId;
+import org.briarproject.api.forum.Forum;
+import org.briarproject.api.introduction.IntroductionRequest;
+
+public class ForumInvitationReceivedEvent extends Event {
+
+	private final Forum forum;
+	private final ContactId contactId;
+
+	public ForumInvitationReceivedEvent(Forum forum, ContactId contactId) {
+		this.forum = forum;
+		this.contactId = contactId;
+	}
+
+	public Forum getForum() {
+		return forum;
+	}
+
+	public ContactId getContactId() {
+		return contactId;
+	}
+}

briar-api/src/org/briarproject/api/event/ForumInvitationResponseReceivedEvent.java

@@ -0,0 +1,24 @@
+package org.briarproject.api.event;
+
+import org.briarproject.api.contact.ContactId;
+
+public class ForumInvitationResponseReceivedEvent extends Event {
+
+	private final String forumName;
+	private final ContactId contactId;
+
+	public ForumInvitationResponseReceivedEvent(String forumName,
+			ContactId contactId) {
+
+		this.forumName = forumName;
+		this.contactId = contactId;
+	}
+
+	public String getForumName() {
+		return forumName;
+	}
+
+	public ContactId getContactId() {
+		return contactId;
+	}
+}

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

@@ -15,4 +15,38 @@ public interface ForumConstants {
 
 	/** The maximum length of a forum post's body in bytes. */
 	int MAX_FORUM_POST_BODY_LENGTH = MAX_MESSAGE_BODY_LENGTH - 1024;
+
+	/* Forum Sharing Constants */
+	String CONTACT_ID = "contactId";
+	String GROUP_ID = "groupId";
+	String TO_BE_SHARED_BY_US = "toBeSharedByUs";
+	String SHARED_BY_US = "sharedByUs";
+	String SHARED_WITH_US = "sharedWithUs";
+	String TYPE = "type";
+	String SESSION_ID = "sessionId";
+	String STORAGE_ID = "storageId";
+	String STATE = "state";
+	String LOCAL = "local";
+	String TIME = "time";
+	String READ = "read";
+	String IS_SHARER = "isSharer";
+	String FORUM_ID = "forumId";
+	String FORUM_NAME = "forumName";
+	String FORUM_SALT = "forumSalt";
+	String INVITATION_MSG = "invitationMsg";
+	int SHARE_MSG_TYPE_INVITATION = 1;
+	int SHARE_MSG_TYPE_ACCEPT = 2;
+	int SHARE_MSG_TYPE_DECLINE = 3;
+	int SHARE_MSG_TYPE_LEAVE = 4;
+	int SHARE_MSG_TYPE_ABORT = 5;
+	String TASK = "task";
+	int TASK_ADD_FORUM_TO_LIST_SHARED_WITH_US = 0;
+	int TASK_REMOVE_FORUM_FROM_LIST_SHARED_WITH_US = 1;
+	int TASK_ADD_SHARED_FORUM = 2;
+	int TASK_ADD_FORUM_TO_LIST_TO_BE_SHARED_BY_US = 3;
+	int TASK_REMOVE_FORUM_FROM_LIST_TO_BE_SHARED_BY_US = 4;
+	int TASK_SHARE_FORUM = 5;
+	int TASK_UNSHARE_FORUM_SHARED_BY_US = 6;
+	int TASK_UNSHARE_FORUM_SHARED_WITH_US = 7;
+
 }

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

@@ -0,0 +1,48 @@
+package org.briarproject.api.forum;
+
+import org.briarproject.api.clients.SessionId;
+import org.briarproject.api.contact.ContactId;
+import org.briarproject.api.messaging.BaseMessage;
+import org.briarproject.api.sync.MessageId;
+
+public class ForumInvitationMessage extends BaseMessage {
+
+	private final SessionId sessionId;
+	private final ContactId contactId;
+	private final String forumName, message;
+	private final boolean available;
+
+	public ForumInvitationMessage(MessageId id, SessionId sessionId,
+			ContactId contactId, String forumName, String message,
+			boolean available, long time, boolean local, boolean sent,
+			boolean seen, boolean read) {
+
+		super(id, time, local, read, sent, seen);
+		this.sessionId = sessionId;
+		this.contactId = contactId;
+		this.forumName = forumName;
+		this.message = message;
+		this.available = available;
+	}
+
+	public SessionId getSessionId() {
+		return sessionId;
+	}
+
+	public ContactId getContactId() {
+		return contactId;
+	}
+
+	public String getForumName() {
+		return forumName;
+	}
+
+	public String getMessage() {
+		return message;
+	}
+
+	public boolean isAvailable() {
+		return available;
+	}
+
+}

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

@@ -31,6 +31,9 @@ public interface ForumManager {
 	/** Returns the forum with the given ID. */
 	Forum getForum(GroupId g) throws DbException;
 
+	/** Returns the forum with the given ID. */
+	Forum getForum(Transaction txn, GroupId g) throws DbException;
+
 	/** Returns all forums to which the user subscribes. */
 	Collection<Forum> getForums() throws DbException;
 

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

@@ -1,5 +1,6 @@
 package org.briarproject.api.forum;
 
+import org.briarproject.api.clients.SessionId;
 import org.briarproject.api.contact.Contact;
 import org.briarproject.api.contact.ContactId;
 import org.briarproject.api.db.DbException;
@@ -13,20 +14,35 @@ public interface ForumSharingManager {
 	/** Returns the unique ID of the forum sharing client. */
 	ClientId getClientId();
 
+	/**
+	 * Sends an invitation to share the given forum with the given contact
+	 * and sends an optional message along with it.
+	 */
+	void sendForumInvitation(GroupId groupId, ContactId contactId,
+			String message)	throws DbException;
+
+	/**
+	 * Responds to a pending forum invitation
+	 */
+	void respondToInvitation(Forum f, boolean accept) throws DbException;
+
+	/**
+	 * Returns all forum sharing messages sent by the Contact
+	 * identified by contactId.
+	 */
+	Collection<ForumInvitationMessage> getForumInvitationMessages(
+			ContactId contactId) throws DbException;
+
 	/** Returns all forums to which the user could subscribe. */
 	Collection<Forum> getAvailableForums() throws DbException;
 
-	/** Returns all contacts who are sharing the given forum with the user. */
+	/** Returns all contacts who are sharing the given forum with us. */
 	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;
 
-	/**
-	 * Shares a forum with the given contacts and unshares it with any other
-	 * contacts.
-	 */
-	void setSharedWith(GroupId g, Collection<ContactId> shared)
-			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/InviteeAction.java

@@ -0,0 +1,34 @@
+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

@@ -0,0 +1,62 @@
+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

@@ -0,0 +1,34 @@
+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

@@ -0,0 +1,62 @@
+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/introduction/IntroductionMessage.java

@@ -1,61 +1,36 @@
 package org.briarproject.api.introduction;
 
 import org.briarproject.api.clients.SessionId;
+import org.briarproject.api.messaging.BaseMessage;
 import org.briarproject.api.sync.MessageId;
 
 import static org.briarproject.api.introduction.IntroductionConstants.ROLE_INTRODUCEE;
 import static org.briarproject.api.introduction.IntroductionConstants.ROLE_INTRODUCER;
 
-abstract public class IntroductionMessage {
+ public class IntroductionMessage extends BaseMessage {
 
 	private final SessionId sessionId;
 	private final MessageId messageId;
 	private final int role;
-	private final long time;
-	private final boolean local, sent, seen, read;
 
 	public IntroductionMessage(SessionId sessionId, MessageId messageId,
 			int role, long time, boolean local, boolean sent, boolean seen,
 			boolean read) {
 
+		super(messageId, time, local, read, sent, seen);
 		this.sessionId = sessionId;
 		this.messageId = messageId;
 		this.role = role;
-		this.time = time;
-		this.local = local;
-		this.sent = sent;
-		this.seen = seen;
-		this.read = read;
 	}
 
 	public SessionId getSessionId() {
 		return sessionId;
 	}
 
-	public long getTime() {
-		return time;
-	}
-
 	public MessageId getMessageId() {
 		return messageId;
 	}
 
-	public boolean isLocal() {
-		return local;
-	}
-
-	public boolean isSent() {
-		return sent;
-	}
-
-	public boolean isSeen() {
-		return seen;
-	}
-
-	public boolean isRead() {
-		return read;
-	}
-
 	public boolean isIntroducer() {
 		return role == ROLE_INTRODUCER;
 	}

briar-api/src/org/briarproject/api/messaging/BaseMessage.java

@@ -0,0 +1,45 @@
+package org.briarproject.api.messaging;
+
+import org.briarproject.api.sync.MessageId;
+
+public abstract class BaseMessage {
+
+	private final MessageId id;
+	private final long timestamp;
+	private final boolean local, read, sent, seen;
+
+	public BaseMessage(MessageId id, long timestamp, boolean local,
+			boolean read, boolean sent, boolean seen) {
+
+		this.id = id;
+		this.timestamp = timestamp;
+		this.local = local;
+		this.read = read;
+		this.sent = sent;
+		this.seen = seen;
+	}
+
+	public MessageId getId() {
+		return id;
+	}
+
+	public long getTimestamp() {
+		return timestamp;
+	}
+
+	public boolean isLocal() {
+		return local;
+	}
+
+	public boolean isRead() {
+		return read;
+	}
+
+	public boolean isSent() {
+		return sent;
+	}
+
+	public boolean isSeen() {
+		return seen;
+	}
+}

briar-api/src/org/briarproject/api/messaging/PrivateMessageHeader.java

@@ -2,50 +2,19 @@ package org.briarproject.api.messaging;
 
 import org.briarproject.api.sync.MessageId;
 
-public class PrivateMessageHeader {
+public class PrivateMessageHeader extends BaseMessage {
 
-	private final MessageId id;
-	private final long timestamp;
 	private final String contentType;
-	private final boolean local, read, sent, seen;
 
 	public PrivateMessageHeader(MessageId id, long timestamp,
 			String contentType, boolean local, boolean read, boolean sent,
 			boolean seen) {
-		this.id = id;
-		this.timestamp = timestamp;
-		this.contentType = contentType;
-		this.local = local;
-		this.read = read;
-		this.sent = sent;
-		this.seen = seen;
-	}
 
-	public MessageId getId() {
-		return id;
+		super(id, timestamp, local, read, sent, seen);
+		this.contentType = contentType;
 	}
 
 	public String getContentType() {
 		return contentType;
 	}
-
-	public long getTimestamp() {
-		return timestamp;
-	}
-
-	public boolean isLocal() {
-		return local;
-	}
-
-	public boolean isRead() {
-		return read;
-	}
-
-	public boolean isSent() {
-		return sent;
-	}
-
-	public boolean isSeen() {
-		return seen;
-	}
 }

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

@@ -24,7 +24,7 @@ public abstract class BdfIncomingMessageHook implements IncomingMessageHook,
 	protected final MetadataParser metadataParser;
 
 	protected BdfIncomingMessageHook(ClientHelper clientHelper,
-			MetadataParser metadataParser, Clock clock) {
+			MetadataParser metadataParser) {
 		this.clientHelper = clientHelper;
 		this.metadataParser = metadataParser;
 	}

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

@@ -1,48 +0,0 @@
-package org.briarproject.forum;
-
-import org.briarproject.api.FormatException;
-import org.briarproject.api.clients.ClientHelper;
-import org.briarproject.api.data.BdfDictionary;
-import org.briarproject.api.data.BdfList;
-import org.briarproject.api.data.MetadataEncoder;
-import org.briarproject.api.sync.Group;
-import org.briarproject.api.sync.Message;
-import org.briarproject.api.system.Clock;
-import org.briarproject.clients.BdfMessageValidator;
-
-import static org.briarproject.api.forum.ForumConstants.FORUM_SALT_LENGTH;
-import static org.briarproject.api.forum.ForumConstants.MAX_FORUM_NAME_LENGTH;
-
-class ForumListValidator extends BdfMessageValidator {
-
-	ForumListValidator(ClientHelper clientHelper,
-			MetadataEncoder metadataEncoder, Clock clock) {
-		super(clientHelper, metadataEncoder, clock);
-	}
-
-	@Override
-	protected BdfDictionary validateMessage(Message m, Group g,
-			BdfList body) throws FormatException {
-		// Version, forum list
-		checkSize(body, 2);
-		// Version
-		long version = body.getLong(0);
-		if (version < 0) throw new FormatException();
-		// Forum list
-		BdfList forumList = body.getList(1);
-		for (int i = 0; i < forumList.size(); i++) {
-			BdfList forum = forumList.getList(i);
-			// Name, salt
-			checkSize(forum, 2);
-			String name = forum.getString(0);
-			checkLength(name, 1, MAX_FORUM_NAME_LENGTH);
-			byte[] salt = forum.getRaw(1);
-			checkLength(salt, FORUM_SALT_LENGTH);
-		}
-		// Return the metadata
-		BdfDictionary meta = new BdfDictionary();
-		meta.put("version", version);
-		meta.put("local", false);
-		return meta;
-	}
-}

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

@@ -141,15 +141,21 @@ class ForumManagerImpl implements ForumManager {
 
 	@Override
 	public Forum getForum(GroupId g) throws DbException {
+		Forum forum;
+		Transaction txn = db.startTransaction(true);
 		try {
-			Group group;
-			Transaction txn = db.startTransaction(true);
-			try {
-				group = db.getGroup(txn, g);
-				txn.setComplete();
-			} finally {
-				db.endTransaction(txn);
-			}
+			forum = getForum(txn, g);
+			txn.setComplete();
+		} finally {
+			db.endTransaction(txn);
+		}
+		return forum;
+	}
+
+	@Override
+	public Forum getForum(Transaction txn, GroupId g) throws DbException {
+		try {
+			Group group = db.getGroup(txn, g);
 			return parseForum(group);
 		} catch (FormatException e) {
 			throw new DbException(e);

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

@@ -1,6 +1,7 @@
 package org.briarproject.forum;
 
 import org.briarproject.api.clients.ClientHelper;
+import org.briarproject.api.clients.MessageQueueManager;
 import org.briarproject.api.contact.ContactManager;
 import org.briarproject.api.crypto.CryptoComponent;
 import org.briarproject.api.data.MetadataEncoder;
@@ -26,11 +27,11 @@ import dagger.Provides;
 public class ForumModule {
 
 	public static class EagerSingletons {
-		@Inject
-		ForumListValidator forumListValidator;
 		@Inject
 		ForumPostValidator forumPostValidator;
 		@Inject
+		ForumSharingValidator forumSharingValidator;
+		@Inject
 		ForumSharingManager forumSharingManager;
 	}
 
@@ -63,13 +64,15 @@ public class ForumModule {
 
 	@Provides
 	@Singleton
-	ForumListValidator provideForumListValidator(
-			ValidationManager validationManager, ClientHelper clientHelper,
+	ForumSharingValidator provideSharingValidator(
+			MessageQueueManager messageQueueManager, ClientHelper clientHelper,
 			MetadataEncoder metadataEncoder, Clock clock) {
-		ForumListValidator validator = new ForumListValidator(clientHelper,
+
+		ForumSharingValidator validator = new ForumSharingValidator(clientHelper,
 				metadataEncoder, clock);
-		validationManager.registerMessageValidator(
+		messageQueueManager.registerMessageValidator(
 				ForumSharingManagerImpl.CLIENT_ID, validator);
+
 		return validator;
 	}
 
@@ -78,15 +81,17 @@ public class ForumModule {
 	ForumSharingManager provideForumSharingManager(
 			LifecycleManager lifecycleManager,
 			ContactManager contactManager,
-			ValidationManager validationManager,
+			MessageQueueManager messageQueueManager,
 			ForumManager forumManager,
 			ForumSharingManagerImpl forumSharingManager) {
+
 		lifecycleManager.registerClient(forumSharingManager);
 		contactManager.registerAddContactHook(forumSharingManager);
 		contactManager.registerRemoveContactHook(forumSharingManager);
-		validationManager.registerIncomingMessageHook(
+		messageQueueManager.registerIncomingMessageHook(
 				ForumSharingManagerImpl.CLIENT_ID, forumSharingManager);
 		forumManager.registerRemoveForumHook(forumSharingManager);
+
 		return forumSharingManager;
 	}
 }

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

@@ -0,0 +1,81 @@
+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.data.BdfDictionary;
+import org.briarproject.api.data.BdfList;
+import org.briarproject.api.data.MetadataEncoder;
+import org.briarproject.api.sync.Group;
+import org.briarproject.api.sync.Message;
+import org.briarproject.api.system.Clock;
+import org.briarproject.clients.BdfMessageValidator;
+
+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.LOCAL;
+import static org.briarproject.api.forum.ForumConstants.MAX_FORUM_NAME_LENGTH;
+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.TIME;
+import static org.briarproject.api.forum.ForumConstants.TYPE;
+import static org.briarproject.api.sync.SyncConstants.MAX_MESSAGE_BODY_LENGTH;
+
+class ForumSharingValidator extends BdfMessageValidator {
+
+	ForumSharingValidator(ClientHelper clientHelper,
+			MetadataEncoder metadataEncoder, Clock clock) {
+		super(clientHelper, metadataEncoder, clock);
+	}
+
+	@Override
+	protected BdfDictionary validateMessage(Message m, Group g,
+			BdfList body) throws FormatException {
+
+		BdfDictionary d = new BdfDictionary();
+		long type = body.getLong(0);
+		byte[] id = body.getRaw(1);
+		checkLength(id, SessionId.LENGTH);
+
+		if (type == SHARE_MSG_TYPE_INVITATION) {
+			checkSize(body, 4, 5);
+
+			String name = body.getString(2);
+			checkLength(name, 1, MAX_FORUM_NAME_LENGTH);
+
+			byte[] salt = body.getRaw(3);
+			checkLength(salt, FORUM_SALT_LENGTH);
+
+			d.put(FORUM_NAME, name);
+			d.put(FORUM_SALT, salt);
+
+			if (body.size() > 4) {
+				String msg = body.getString(4);
+				checkLength(msg, 0, MAX_MESSAGE_BODY_LENGTH);
+				d.put(INVITATION_MSG, msg);
+			}
+		} else {
+			checkSize(body, 2);
+			if (type != SHARE_MSG_TYPE_ACCEPT &&
+					type != SHARE_MSG_TYPE_DECLINE &&
+					type != SHARE_MSG_TYPE_LEAVE &&
+					type != SHARE_MSG_TYPE_ABORT) {
+				throw new FormatException();
+			}
+		}
+		// 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;
+	}
+}

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

@@ -0,0 +1,265 @@
+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 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;
+
+public class InviteeEngine
+		implements ProtocolEngine<BdfDictionary, BdfDictionary, BdfDictionary> {
+
+	private static final Logger LOG =
+			Logger.getLogger(SharerEngine.class.getName());
+
+	@Override
+	public StateUpdate<BdfDictionary, BdfDictionary> onLocalAction(
+			BdfDictionary localState, BdfDictionary localAction) {
+
+		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());
+
+			if (action == LOCAL_ABORT && currentState != ERROR) {
+				return abortSession(currentState, localState);
+			}
+
+			if (nextState == ERROR) {
+				if (LOG.isLoggable(WARNING)) {
+					LOG.warning("Error: Invalid action in state " +
+							currentState.name());
+				}
+				return noUpdate(localState, true);
+			}
+			List<BdfDictionary> 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))
+				);
+				if (action == LOCAL_ACCEPT) {
+					localState.put(TASK, TASK_ADD_SHARED_FORUM);
+					msg.put(TYPE, SHARE_MSG_TYPE_ACCEPT);
+				} else {
+					localState.put(TASK,
+							TASK_REMOVE_FORUM_FROM_LIST_SHARED_WITH_US);
+					msg.put(TYPE, SHARE_MSG_TYPE_DECLINE);
+				}
+				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));
+				messages = Collections.singletonList(msg);
+				logLocalAction(currentState, localState, msg);
+			}
+			else {
+				throw new IllegalArgumentException("Unknown Local Action");
+			}
+			return new StateUpdate<BdfDictionary, BdfDictionary>(false,
+					false, localState, messages, events);
+		} catch (FormatException e) {
+			throw new IllegalArgumentException(e);
+		}
+	}
+
+	@Override
+	public StateUpdate<BdfDictionary, BdfDictionary> onMessageReceived(
+			BdfDictionary localState, BdfDictionary 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());
+
+			logMessageReceived(currentState, nextState, type, msg);
+
+			if (nextState == ERROR) {
+				if (currentState != ERROR) {
+					return abortSession(currentState, localState);
+				} else {
+					return noUpdate(localState, true);
+				}
+			}
+
+			List<BdfDictionary> messages = Collections.emptyList();
+			List<Event> events = Collections.emptyList();
+			boolean deleteMsg = false;
+
+			if (currentState == LEFT) {
+				// ignore and delete messages coming in while in that state
+				deleteMsg = true;
+			}
+			// 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);
+			}
+			else if (currentState == FINISHED) {
+				// ignore and delete messages coming in while in that state
+				// note that LEAVE is possible, but was handled above
+				deleteMsg = true;
+			}
+			// 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);
+			}
+			// 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());
+				Event event = new ForumInvitationReceivedEvent(forum, contactId);
+				events = Collections.singletonList(event);
+			}
+			else {
+				throw new IllegalArgumentException("Bad state");
+			}
+			return new StateUpdate<BdfDictionary, BdfDictionary>(deleteMsg,
+					false, localState, messages, events);
+		} catch (FormatException e) {
+			throw new IllegalArgumentException(e);
+		}
+	}
+
+	private void logLocalAction(InviteeProtocolState state,
+			BdfDictionary localState, BdfDictionary msg) {
+
+		if (!LOG.isLoggable(INFO)) return;
+
+		String a = "response";
+		if (msg.getLong(TYPE, -1L) == 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);
+		}
+	}
+
+	private void logMessageReceived(InviteeProtocolState currentState,
+			InviteeProtocolState nextState, long type, BdfDictionary 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";
+
+			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);
+		}
+	}
+
+	@Override
+	public StateUpdate<BdfDictionary, BdfDictionary> onMessageDelivered(
+			BdfDictionary localState, BdfDictionary delivered) {
+		try {
+			return noUpdate(localState, false);
+		} catch (FormatException e) {
+			if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
+			return null;
+		}
+	}
+
+	private InviteeProtocolState getState(Long state) {
+		return InviteeProtocolState.fromValue(state.intValue());
+	}
+
+	private StateUpdate<BdfDictionary, BdfDictionary> abortSession(
+			InviteeProtocolState currentState, BdfDictionary localState)
+			throws FormatException {
+
+		if (LOG.isLoggable(WARNING)) {
+			LOG.warning("Aborting protocol session " +
+					Arrays.hashCode(localState.getRaw(SESSION_ID)) +
+					" 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);
+
+		List<Event> events = Collections.emptyList();
+
+		return new StateUpdate<BdfDictionary, BdfDictionary>(false, false,
+				localState, messages, events);
+	}
+
+	private StateUpdate<BdfDictionary, BdfDictionary> noUpdate(
+			BdfDictionary localState, boolean delete) throws FormatException {
+
+		return new StateUpdate<BdfDictionary, BdfDictionary>(delete, false,
+				localState, Collections.<BdfDictionary>emptyList(),
+				Collections.<Event>emptyList());
+	}
+}

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

@@ -0,0 +1,264 @@
+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;
+
+public class SharerEngine
+		implements ProtocolEngine<BdfDictionary, BdfDictionary, BdfDictionary> {
+
+	private static final Logger LOG =
+			Logger.getLogger(SharerEngine.class.getName());
+
+	@Override
+	public StateUpdate<BdfDictionary, BdfDictionary> onLocalAction(
+			BdfDictionary localState, BdfDictionary localAction) {
+
+		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());
+
+			if (action == LOCAL_ABORT && currentState != ERROR) {
+				return abortSession(currentState, localState);
+			}
+
+			if (nextState == ERROR) {
+				if (LOG.isLoggable(WARNING)) {
+					LOG.warning("Error: Invalid action in state " +
+							currentState.name());
+				}
+				return noUpdate(localState, true);
+			}
+			List<BdfDictionary> 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));
+				}
+				messages = Collections.singletonList(msg);
+				logLocalAction(currentState, localState, msg);
+
+				// remember that we offered to share this forum
+				localState.put(TASK, 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));
+				messages = Collections.singletonList(msg);
+				logLocalAction(currentState, localState, msg);
+			}
+			else {
+				throw new IllegalArgumentException("Unknown Local Action");
+			}
+			return new StateUpdate<BdfDictionary, BdfDictionary>(false,
+					false, localState, messages, events);
+		} catch (FormatException e) {
+			throw new IllegalArgumentException(e);
+		}
+	}
+
+	@Override
+	public StateUpdate<BdfDictionary, BdfDictionary> onMessageReceived(
+			BdfDictionary localState, BdfDictionary 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());
+
+			logMessageReceived(currentState, nextState, type, msg);
+
+			if (nextState == ERROR) {
+				if (currentState != ERROR) {
+					return abortSession(currentState, localState);
+				} else {
+					return noUpdate(localState, true);
+				}
+			}
+			List<BdfDictionary> messages = Collections.emptyList();
+			List<Event> events = Collections.emptyList();
+			boolean deleteMsg = false;
+
+			if (currentState == LEFT) {
+				// ignore and delete messages coming in while in that state
+				deleteMsg = true;
+			}
+			else if (action == REMOTE_LEAVE) {
+				localState.put(TASK, TASK_UNSHARE_FORUM_SHARED_BY_US);
+			}
+			else if (currentState == FINISHED) {
+				// ignore and delete messages coming in while in that state
+				// note that LEAVE is possible, but was handled above
+				deleteMsg = true;
+			}
+			// 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);
+				} else {
+					// this ensures that the forum can be shared again
+					localState.put(TASK,
+							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());
+				Event event = new ForumInvitationResponseReceivedEvent(name, c);
+				events = Collections.singletonList(event);
+			}
+			else {
+				throw new IllegalArgumentException("Bad state");
+			}
+			return new StateUpdate<BdfDictionary, BdfDictionary>(deleteMsg,
+					false, localState, messages, events);
+		} catch (FormatException e) {
+			throw new IllegalArgumentException(e);
+		}
+	}
+
+	private void logLocalAction(SharerProtocolState state,
+			BdfDictionary localState, BdfDictionary msg) {
+
+		if (!LOG.isLoggable(INFO)) return;
+
+		String a = "invitation";
+		if (msg.getLong(TYPE, -1L) == 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);
+		}
+	}
+
+	private void logMessageReceived(SharerProtocolState currentState,
+			SharerProtocolState nextState, long type, BdfDictionary 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";
+
+			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);
+		}
+	}
+
+	@Override
+	public StateUpdate<BdfDictionary, BdfDictionary> onMessageDelivered(
+			BdfDictionary localState, BdfDictionary delivered) {
+		try {
+			return noUpdate(localState, false);
+		} catch (FormatException e) {
+			if (LOG.isLoggable(WARNING)) LOG.log(WARNING, e.toString(), e);
+			return null;
+		}
+	}
+
+	private SharerProtocolState getState(Long state) {
+		 return SharerProtocolState.fromValue(state.intValue());
+	}
+
+	private StateUpdate<BdfDictionary, BdfDictionary> abortSession(
+			SharerProtocolState currentState, BdfDictionary localState)
+			throws FormatException {
+
+		if (LOG.isLoggable(WARNING)) {
+			LOG.warning("Aborting protocol session " +
+					Arrays.hashCode(localState.getRaw(SESSION_ID)) +
+					" 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);
+
+		List<Event> events = Collections.emptyList();
+
+		return new StateUpdate<BdfDictionary, BdfDictionary>(false, false,
+				localState, messages, events);
+	}
+
+	private StateUpdate<BdfDictionary, BdfDictionary> noUpdate(
+			BdfDictionary localState, boolean delete) throws FormatException {
+
+		return new StateUpdate<BdfDictionary, BdfDictionary>(delete, false,
+				localState, Collections.<BdfDictionary>emptyList(),
+				Collections.<Event>emptyList());
+	}
+}

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

@@ -3,6 +3,7 @@ package org.briarproject.introduction;
 import org.briarproject.api.FormatException;
 import org.briarproject.api.clients.Client;
 import org.briarproject.api.clients.ClientHelper;
+import org.briarproject.api.clients.SessionId;
 import org.briarproject.api.contact.Contact;
 import org.briarproject.api.contact.ContactId;
 import org.briarproject.api.contact.ContactManager.AddContactHook;
@@ -20,14 +21,12 @@ import org.briarproject.api.introduction.IntroductionManager;
 import org.briarproject.api.introduction.IntroductionMessage;
 import org.briarproject.api.introduction.IntroductionRequest;
 import org.briarproject.api.introduction.IntroductionResponse;
-import org.briarproject.api.clients.SessionId;
 import org.briarproject.api.sync.ClientId;
 import org.briarproject.api.sync.Group;
 import org.briarproject.api.sync.GroupId;
 import org.briarproject.api.sync.Message;
 import org.briarproject.api.sync.MessageId;
 import org.briarproject.api.sync.MessageStatus;
-import org.briarproject.api.system.Clock;
 import org.briarproject.clients.BdfIncomingMessageHook;
 import org.briarproject.util.StringUtils;
 
@@ -93,12 +92,11 @@ class IntroductionManagerImpl extends BdfIncomingMessageHook
 
 	@Inject
 	IntroductionManagerImpl(DatabaseComponent db, ClientHelper clientHelper,
-			MetadataParser metadataParser, Clock clock,
-			IntroducerManager introducerManager,
+			MetadataParser metadataParser, IntroducerManager introducerManager,
 			IntroduceeManager introduceeManager,
 			IntroductionGroupFactory introductionGroupFactory) {
 
-		super(clientHelper, metadataParser, clock);
+		super(clientHelper, metadataParser);
 		this.db = db;
 		this.introducerManager = introducerManager;
 		this.introduceeManager = introduceeManager;

briar-tests/src/org/briarproject/forum/ForumSharingValidatorTest.java

@@ -5,7 +5,7 @@ import org.junit.Test;
 
 import static org.junit.Assert.fail;
 
-public class ForumListValidatorTest extends BriarTestCase {
+public class ForumSharingValidatorTest extends BriarTestCase {
 
 	@Test
 	public void testUnitTestsExist() {

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

@@ -118,7 +118,7 @@ public class IntroductionManagerImplTest extends BriarTestCase {
 		clock = context.mock(Clock.class);
 
 		introductionManager = new IntroductionManagerImpl(
-				db, clientHelper, metadataParser, clock, introducerManager,
+				db, clientHelper, metadataParser, introducerManager,
 				introduceeManager, introductionGroupFactory
 		);
 	}