Only cache attachment items that include size.

Improve crash screen and reporter

Closes #1426, #1061, #1390, #1012, and #1054

See merge request briar/briar!1049

bramble-api/src/main/java/org/briarproject/bramble/api/FeatureFlags.java

@@ -0,0 +1,11 @@
+package org.briarproject.bramble.api;
+
+/**
+ * Interface for specifying which features are enabled in a build.
+ */
+public interface FeatureFlags {
+
+	boolean shouldEnableImageAttachments();
+
+	boolean shouldEnableRemoteContacts();
+}

bramble-api/src/main/java/org/briarproject/bramble/api/client/ClientHelper.java

@@ -25,7 +25,10 @@ public interface ClientHelper {
 			throws DbException, FormatException;
 
 	void addLocalMessage(Transaction txn, Message m, BdfDictionary metadata,
-			boolean shared) throws DbException, FormatException;
+			boolean shared, boolean temporary)
+			throws DbException, FormatException;
+
+	Message createMessage(GroupId g, long timestamp, byte[] body);
 
 	Message createMessage(GroupId g, long timestamp, BdfList body)
 			throws FormatException;
@@ -108,7 +111,7 @@ public interface ClientHelper {
 	Author parseAndValidateAuthor(BdfList author) throws FormatException;
 
 	PublicKey parseAndValidateAgreementPublicKey(byte[] publicKeyBytes)
-		throws FormatException;
+			throws FormatException;
 
 	TransportProperties parseAndValidateTransportProperties(
 			BdfDictionary properties) throws FormatException;

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

@@ -3,6 +3,7 @@ package org.briarproject.bramble.api.contact;
 public enum PendingContactState {
 
 	WAITING_FOR_CONNECTION,
+	OFFLINE,
 	CONNECTING,
 	ADDING_CONTACT,
 	FAILED

bramble-api/src/main/java/org/briarproject/bramble/api/db/DatabaseComponent.java

@@ -29,6 +29,7 @@ import org.briarproject.bramble.api.transport.TransportKeySet;
 import org.briarproject.bramble.api.transport.TransportKeys;
 
 import java.util.Collection;
+import java.util.List;
 import java.util.Map;
 
 import javax.annotation.Nullable;
@@ -77,7 +78,7 @@ public interface DatabaseComponent extends TransactionManager {
 	 * Stores a local message.
 	 */
 	void addLocalMessage(Transaction txn, Message m, Metadata meta,
-			boolean shared) throws DbException;
+			boolean shared, boolean temporary) throws DbException;
 
 	/**
 	 * Stores a pending contact.
@@ -427,6 +428,13 @@ public interface DatabaseComponent extends TransactionManager {
 	 */
 	Settings getSettings(Transaction txn, String namespace) throws DbException;
 
+	/**
+	 * Returns the versions of the sync protocol supported by the given contact.
+	 * <p/>
+	 * Read-only.
+	 */
+	List<Byte> getSyncVersions(Transaction txn, ContactId c) throws DbException;
+
 	/**
 	 * Returns all transport keys for the given transport.
 	 * <p/>
@@ -510,6 +518,12 @@ public interface DatabaseComponent extends TransactionManager {
 	void removePendingContact(Transaction txn, PendingContactId p)
 			throws DbException;
 
+	/**
+	 * Removes all temporary messages (and all associated state) from the
+	 * database.
+	 */
+	void removeTemporaryMessages(Transaction txn) throws DbException;
+
 	/**
 	 * Removes a transport (and all associated state) from the database.
 	 */
@@ -538,6 +552,11 @@ public interface DatabaseComponent extends TransactionManager {
 	void setGroupVisibility(Transaction txn, ContactId c, GroupId g,
 			Visibility v) throws DbException;
 
+	/**
+	 * Marks the given message as permanent, i.e. not temporary.
+	 */
+	void setMessagePermanent(Transaction txn, MessageId m) throws DbException;
+
 	/**
 	 * Marks the given message as shared.
 	 */
@@ -568,6 +587,12 @@ public interface DatabaseComponent extends TransactionManager {
 	void setReorderingWindow(Transaction txn, KeySetId k, TransportId t,
 			long timePeriod, long base, byte[] bitmap) throws DbException;
 
+	/**
+	 * Sets the versions of the sync protocol supported by the given contact.
+	 */
+	void setSyncVersions(Transaction txn, ContactId c, List<Byte> supported)
+			throws DbException;
+
 	/**
 	 * Marks the given transport keys as usable for outgoing streams.
 	 */

bramble-api/src/main/java/org/briarproject/bramble/api/sync/Ack.java

@@ -1,10 +1,16 @@
 package org.briarproject.bramble.api.sync;
 
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
 import java.util.Collection;
 
+import javax.annotation.concurrent.Immutable;
+
 /**
  * A record acknowledging receipt of one or more {@link Message Messages}.
  */
+@Immutable
+@NotNullByDefault
 public class Ack {
 
 	private final Collection<MessageId> acked;

bramble-api/src/main/java/org/briarproject/bramble/api/sync/Message.java

@@ -1,8 +1,14 @@
 package org.briarproject.bramble.api.sync;
 
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import javax.annotation.concurrent.Immutable;
+
 import static org.briarproject.bramble.api.sync.SyncConstants.MAX_MESSAGE_BODY_LENGTH;
 import static org.briarproject.bramble.api.sync.SyncConstants.MESSAGE_HEADER_LENGTH;
 
+@Immutable
+@NotNullByDefault
 public class Message {
 
 	/**

bramble-api/src/main/java/org/briarproject/bramble/api/sync/Offer.java

@@ -1,10 +1,16 @@
 package org.briarproject.bramble.api.sync;
 
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
 import java.util.Collection;
 
+import javax.annotation.concurrent.Immutable;
+
 /**
  * A record offering the recipient one or more {@link Message Messages}.
  */
+@Immutable
+@NotNullByDefault
 public class Offer {
 
 	private final Collection<MessageId> offered;

bramble-api/src/main/java/org/briarproject/bramble/api/sync/RecordTypes.java

@@ -9,5 +9,5 @@ public interface RecordTypes {
 	byte MESSAGE = 1;
 	byte OFFER = 2;
 	byte REQUEST = 3;
-
+	byte VERSIONS = 4;
 }

bramble-api/src/main/java/org/briarproject/bramble/api/sync/Request.java

@@ -1,10 +1,16 @@
 package org.briarproject.bramble.api.sync;
 
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
 import java.util.Collection;
 
+import javax.annotation.concurrent.Immutable;
+
 /**
  * A record requesting one or more {@link Message Messages} from the recipient.
  */
+@Immutable
+@NotNullByDefault
 public class Request {
 
 	private final Collection<MessageId> requested;

bramble-api/src/main/java/org/briarproject/bramble/api/sync/SyncConstants.java

@@ -2,6 +2,9 @@ package org.briarproject.bramble.api.sync;
 
 import org.briarproject.bramble.api.UniqueId;
 
+import java.util.List;
+
+import static java.util.Collections.singletonList;
 import static org.briarproject.bramble.api.record.Record.MAX_RECORD_PAYLOAD_BYTES;
 
 public interface SyncConstants {
@@ -11,6 +14,11 @@ public interface SyncConstants {
 	 */
 	byte PROTOCOL_VERSION = 0;
 
+	/**
+	 * The versions of the sync protocol this peer supports.
+	 */
+	List<Byte> SUPPORTED_VERSIONS = singletonList(PROTOCOL_VERSION);
+
 	/**
 	 * The maximum length of a group descriptor in bytes.
 	 */
@@ -35,4 +43,10 @@ public interface SyncConstants {
 	 * The maximum number of message IDs in an ack, offer or request record.
 	 */
 	int MAX_MESSAGE_IDS = MAX_RECORD_PAYLOAD_BYTES / UniqueId.LENGTH;
+
+	/**
+	 * The maximum number of versions of the sync protocol a peer may support
+	 * simultaneously.
+	 */
+	int MAX_SUPPORTED_VERSIONS = 10;
 }

bramble-api/src/main/java/org/briarproject/bramble/api/sync/SyncRecordReader.java

@@ -25,4 +25,7 @@ public interface SyncRecordReader {
 
 	Request readRequest() throws IOException;
 
+	boolean hasVersions() throws IOException;
+
+	Versions readVersions() throws IOException;
 }

bramble-api/src/main/java/org/briarproject/bramble/api/sync/SyncRecordWriter.java

@@ -15,5 +15,7 @@ public interface SyncRecordWriter {
 
 	void writeRequest(Request r) throws IOException;
 
+	void writeVersions(Versions v) throws IOException;
+
 	void flush() throws IOException;
 }

bramble-api/src/main/java/org/briarproject/bramble/api/sync/Versions.java

@@ -0,0 +1,26 @@
+package org.briarproject.bramble.api.sync;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import java.util.List;
+
+import javax.annotation.concurrent.Immutable;
+
+/**
+ * A record telling the recipient which versions of the sync protocol the
+ * sender supports.
+ */
+@Immutable
+@NotNullByDefault
+public class Versions {
+
+	private final List<Byte> supported;
+
+	public Versions(List<Byte> supported) {
+		this.supported = supported;
+	}
+
+	public List<Byte> getSupportedVersions() {
+		return supported;
+	}
+}

bramble-api/src/main/java/org/briarproject/bramble/api/sync/event/SyncVersionsUpdatedEvent.java

@@ -0,0 +1,34 @@
+package org.briarproject.bramble.api.sync.event;
+
+import org.briarproject.bramble.api.contact.ContactId;
+import org.briarproject.bramble.api.event.Event;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import java.util.List;
+
+import javax.annotation.concurrent.Immutable;
+
+/**
+ * An event that is broadcast when the versions of the sync protocol supported
+ * by a contact are updated.
+ */
+@Immutable
+@NotNullByDefault
+public class SyncVersionsUpdatedEvent extends Event {
+
+	private final ContactId contactId;
+	private final List<Byte> supported;
+
+	public SyncVersionsUpdatedEvent(ContactId contactId, List<Byte> supported) {
+		this.contactId = contactId;
+		this.supported = supported;
+	}
+
+	public ContactId getContactId() {
+		return contactId;
+	}
+
+	public List<Byte> getSupportedVersions() {
+		return supported;
+	}
+}

bramble-core/src/main/java/org/briarproject/bramble/client/ClientHelperImpl.java

@@ -85,14 +85,21 @@ class ClientHelperImpl implements ClientHelper {
 	@Override
 	public void addLocalMessage(Message m, BdfDictionary metadata,
 			boolean shared) throws DbException, FormatException {
-		db.transaction(false, txn -> addLocalMessage(txn, m, metadata, shared));
+		db.transaction(false, txn -> addLocalMessage(txn, m, metadata, shared,
+				false));
 	}
 
 	@Override
 	public void addLocalMessage(Transaction txn, Message m,
-			BdfDictionary metadata, boolean shared)
+			BdfDictionary metadata, boolean shared, boolean temporary)
 			throws DbException, FormatException {
-		db.addLocalMessage(txn, m, metadataEncoder.encode(metadata), shared);
+		db.addLocalMessage(txn, m, metadataEncoder.encode(metadata), shared,
+				temporary);
+	}
+
+	@Override
+	public Message createMessage(GroupId g, long timestamp, byte[] body) {
+		return messageFactory.createMessage(g, timestamp, body);
 	}
 
 	@Override

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

@@ -147,7 +147,6 @@ class ContactManagerImpl implements ContactManager, EventListener {
 		} finally {
 			db.endTransaction(txn);
 		}
-		states.put(p.getId(), WAITING_FOR_CONNECTION);
 		return p;
 	}
 

bramble-core/src/main/java/org/briarproject/bramble/db/Database.java

@@ -33,6 +33,7 @@ import org.briarproject.bramble.api.transport.TransportKeySet;
 import org.briarproject.bramble.api.transport.TransportKeys;
 
 import java.util.Collection;
+import java.util.List;
 import java.util.Map;
 
 import javax.annotation.Nullable;
@@ -115,7 +116,7 @@ interface Database<T> {
 	 * if the message was created locally.
 	 */
 	void addMessage(T txn, Message m, MessageState state, boolean shared,
-			@Nullable ContactId sender) throws DbException;
+			boolean temporary, @Nullable ContactId sender) throws DbException;
 
 	/**
 	 * Adds a dependency between two messages, where the dependent message is
@@ -528,6 +529,13 @@ interface Database<T> {
 	 */
 	Settings getSettings(T txn, String namespace) throws DbException;
 
+	/**
+	 * Returns the versions of the sync protocol supported by the given contact.
+	 * <p/>
+	 * Read-only.
+	 */
+	List<Byte> getSyncVersions(T txn, ContactId c) throws DbException;
+
 	/**
 	 * Returns all transport keys for the given transport.
 	 * <p/>
@@ -630,6 +638,12 @@ interface Database<T> {
 	 */
 	void removePendingContact(T txn, PendingContactId p) throws DbException;
 
+	/**
+	 * Removes all temporary messages (and all associated state) from the
+	 * database.
+	 */
+	void removeTemporaryMessages(T txn) throws DbException;
+
 	/**
 	 * Removes a transport (and all associated state) from the database.
 	 */
@@ -671,6 +685,11 @@ interface Database<T> {
 	void setHandshakeKeyPair(T txn, AuthorId local, PublicKey publicKey,
 			PrivateKey privateKey) throws DbException;
 
+	/**
+	 * Marks the given message as permanent, i.e. not temporary.
+	 */
+	void setMessagePermanent(T txn, MessageId m) throws DbException;
+
 	/**
 	 * Marks the given message as shared.
 	 */
@@ -689,6 +708,12 @@ interface Database<T> {
 	void setReorderingWindow(T txn, KeySetId k, TransportId t,
 			long timePeriod, long base, byte[] bitmap) throws DbException;
 
+	/**
+	 * Sets the versions of the sync protocol supported by the given contact.
+	 */
+	void setSyncVersions(T txn, ContactId c, List<Byte> supported)
+			throws DbException;
+
 	/**
 	 * Marks the given transport keys as usable for outgoing streams.
 	 */

bramble-core/src/main/java/org/briarproject/bramble/db/DatabaseComponentImpl.java

@@ -65,6 +65,7 @@ import org.briarproject.bramble.api.sync.event.MessageToAckEvent;
 import org.briarproject.bramble.api.sync.event.MessageToRequestEvent;
 import org.briarproject.bramble.api.sync.event.MessagesAckedEvent;
 import org.briarproject.bramble.api.sync.event.MessagesSentEvent;
+import org.briarproject.bramble.api.sync.event.SyncVersionsUpdatedEvent;
 import org.briarproject.bramble.api.sync.validation.MessageState;
 import org.briarproject.bramble.api.transport.KeySetId;
 import org.briarproject.bramble.api.transport.TransportKeySet;
@@ -273,13 +274,14 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 
 	@Override
 	public void addLocalMessage(Transaction transaction, Message m,
-			Metadata meta, boolean shared) throws DbException {
+			Metadata meta, boolean shared, boolean temporary)
+			throws DbException {
 		if (transaction.isReadOnly()) throw new IllegalArgumentException();
 		T txn = unbox(transaction);
 		if (!db.containsGroup(txn, m.getGroupId()))
 			throw new NoSuchGroupException();
 		if (!db.containsMessage(txn, m.getId())) {
-			db.addMessage(txn, m, DELIVERED, shared, null);
+			db.addMessage(txn, m, DELIVERED, shared, temporary, null);
 			transaction.attach(new MessageAddedEvent(m, null));
 			transaction.attach(new MessageStateChangedEvent(m.getId(), true,
 					DELIVERED));
@@ -715,6 +717,15 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 		return db.getSettings(txn, namespace);
 	}
 
+	@Override
+	public List<Byte> getSyncVersions(Transaction transaction, ContactId c)
+			throws DbException {
+		T txn = unbox(transaction);
+		if (!db.containsContact(txn, c))
+			throw new NoSuchContactException();
+		return db.getSyncVersions(txn, c);
+	}
+
 	@Override
 	public Collection<TransportKeySet> getTransportKeys(Transaction transaction,
 			TransportId t) throws DbException {
@@ -800,7 +811,7 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 				db.raiseSeenFlag(txn, c, m.getId());
 				db.raiseAckFlag(txn, c, m.getId());
 			} else {
-				db.addMessage(txn, m, UNKNOWN, false, c);
+				db.addMessage(txn, m, UNKNOWN, false, false, c);
 				transaction.attach(new MessageAddedEvent(m, c));
 			}
 			transaction.attach(new MessageToAckEvent(c));
@@ -908,6 +919,14 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 		transaction.attach(new PendingContactRemovedEvent(p));
 	}
 
+	@Override
+	public void removeTemporaryMessages(Transaction transaction)
+			throws DbException {
+		if (transaction.isReadOnly()) throw new IllegalArgumentException();
+		T txn = unbox(transaction);
+		db.removeTemporaryMessages(txn);
+	}
+
 	@Override
 	public void removeTransport(Transaction transaction, TransportId t)
 			throws DbException {
@@ -967,6 +986,16 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 		transaction.attach(new GroupVisibilityUpdatedEvent(affected));
 	}
 
+	@Override
+	public void setMessagePermanent(Transaction transaction, MessageId m)
+			throws DbException {
+		if (transaction.isReadOnly()) throw new IllegalArgumentException();
+		T txn = unbox(transaction);
+		if (!db.containsMessage(txn, m))
+			throw new NoSuchMessageException();
+		db.setMessagePermanent(txn, m);
+	}
+
 	@Override
 	public void setMessageShared(Transaction transaction, MessageId m)
 			throws DbException {
@@ -975,8 +1004,7 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 		if (!db.containsMessage(txn, m))
 			throw new NoSuchMessageException();
 		if (db.getMessageState(txn, m) != DELIVERED)
-			throw new IllegalArgumentException(
+			throw new IllegalArgumentException("Shared undelivered message");
-					"Shared undelivered message");
 		db.setMessageShared(txn, m);
 		transaction.attach(new MessageSharedEvent(m));
 	}
@@ -1028,6 +1056,17 @@ class DatabaseComponentImpl<T> implements DatabaseComponent {
 		db.setReorderingWindow(txn, k, t, timePeriod, base, bitmap);
 	}
 
+	@Override
+	public void setSyncVersions(Transaction transaction, ContactId c,
+			List<Byte> supported) throws DbException {
+		if (transaction.isReadOnly()) throw new IllegalArgumentException();
+		T txn = unbox(transaction);
+		if (!db.containsContact(txn, c))
+			throw new NoSuchContactException();
+		db.setSyncVersions(txn, c, supported);
+		transaction.attach(new SyncVersionsUpdatedEvent(c, supported));
+	}
+
 	@Override
 	public void setTransportKeysActive(Transaction transaction, TransportId t,
 			KeySetId k) throws DbException {

bramble-core/src/main/java/org/briarproject/bramble/db/JdbcDatabase.java

@@ -62,6 +62,7 @@ import java.util.concurrent.locks.ReentrantLock;
 import java.util.logging.Logger;
 
 import javax.annotation.Nullable;
+import javax.annotation.concurrent.GuardedBy;
 
 import static java.sql.Types.BINARY;
 import static java.sql.Types.BOOLEAN;
@@ -97,7 +98,7 @@ import static org.briarproject.bramble.util.LogUtils.now;
 abstract class JdbcDatabase implements Database<Connection> {
 
 	// Package access for testing
-	static final int CODE_SCHEMA_VERSION = 45;
+	static final int CODE_SCHEMA_VERSION = 47;
 
 	// Time period offsets for incoming transport keys
 	private static final int OFFSET_PREV = -1;
@@ -134,6 +135,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 					+ " handshakePublicKey _BINARY," // Null if key is unknown
 					+ " localAuthorId _HASH NOT NULL,"
 					+ " verified BOOLEAN NOT NULL,"
+					+ " syncVersions _BINARY DEFAULT '00' NOT NULL,"
 					+ " PRIMARY KEY (contactId),"
 					+ " FOREIGN KEY (localAuthorId)"
 					+ " REFERENCES localAuthors (authorId)"
@@ -177,6 +179,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 					+ " timestamp BIGINT NOT NULL,"
 					+ " state INT NOT NULL,"
 					+ " shared BOOLEAN NOT NULL,"
+					+ " temporary BOOLEAN NOT NULL,"
 					+ " length INT NOT NULL,"
 					+ " raw BLOB," // Null if message has been deleted
 					+ " PRIMARY KEY (messageId),"
@@ -336,25 +339,26 @@ abstract class JdbcDatabase implements Database<Connection> {
 	private static final Logger LOG =
 			getLogger(JdbcDatabase.class.getName());
 
-	// Different database libraries use different names for certain types
 	private final MessageFactory messageFactory;
 	private final Clock clock;
 	private final DatabaseTypes dbTypes;
 
-	// Locking: connectionsLock
+	private final Lock connectionsLock = new ReentrantLock();
+	private final Condition connectionsChanged = connectionsLock.newCondition();
+
+	@GuardedBy("connectionsLock")
 	private final LinkedList<Connection> connections = new LinkedList<>();
 
-	private int openConnections = 0; // Locking: connectionsLock
+	@GuardedBy("connectionsLock")
-	private boolean closed = false; // Locking: connectionsLock
+	private int openConnections = 0;
+	@GuardedBy("connectionsLock")
+	private boolean closed = false;
 
 	protected abstract Connection createConnection()
 			throws DbException, SQLException;
 
 	protected abstract void compactAndClose() throws DbException;
 
-	private final Lock connectionsLock = new ReentrantLock();
-	private final Condition connectionsChanged = connectionsLock.newCondition();
-
 	JdbcDatabase(DatabaseTypes databaseTypes, MessageFactory messageFactory,
 			Clock clock) {
 		this.dbTypes = databaseTypes;
@@ -457,7 +461,9 @@ abstract class JdbcDatabase implements Database<Connection> {
 				new Migration41_42(dbTypes),
 				new Migration42_43(dbTypes),
 				new Migration43_44(dbTypes),
-				new Migration44_45()
+				new Migration44_45(),
+				new Migration45_46(),
+				new Migration46_47(dbTypes)
 		);
 	}
 
@@ -777,22 +783,23 @@ abstract class JdbcDatabase implements Database<Connection> {
 
 	@Override
 	public void addMessage(Connection txn, Message m, MessageState state,
-			boolean messageShared, @Nullable ContactId sender)
+			boolean shared, boolean temporary, @Nullable ContactId sender)
 			throws DbException {
 		PreparedStatement ps = null;
 		try {
 			String sql = "INSERT INTO messages (messageId, groupId, timestamp,"
-					+ " state, shared, length, raw)"
+					+ " state, shared, temporary, length, raw)"
-					+ " VALUES (?, ?, ?, ?, ?, ?, ?)";
+					+ " VALUES (?, ?, ?, ?, ?, ?, ?, ?)";
 			ps = txn.prepareStatement(sql);
 			ps.setBytes(1, m.getId().getBytes());
 			ps.setBytes(2, m.getGroupId().getBytes());
 			ps.setLong(3, m.getTimestamp());
 			ps.setInt(4, state.getValue());
-			ps.setBoolean(5, messageShared);
+			ps.setBoolean(5, shared);
+			ps.setBoolean(6, temporary);
 			byte[] raw = messageFactory.getRawMessage(m);
-			ps.setInt(6, raw.length);
+			ps.setInt(7, raw.length);
-			ps.setBytes(7, raw);
+			ps.setBytes(8, raw);
 			int affected = ps.executeUpdate();
 			if (affected != 1) throw new DbStateException();
 			ps.close();
@@ -804,8 +811,7 @@ abstract class JdbcDatabase implements Database<Connection> {
 				boolean offered = removeOfferedMessage(txn, c, m.getId());
 				boolean seen = offered || c.equals(sender);
 				addStatus(txn, m.getId(), c, m.getGroupId(), m.getTimestamp(),
-						raw.length, state, e.getValue(), messageShared,
+						raw.length, state, e.getValue(), shared, false, seen);
-						false, seen);
 			}
 			// Update denormalised column in messageDependencies if dependency
 			// is in same group as dependent
@@ -2324,6 +2330,32 @@ abstract class JdbcDatabase implements Database<Connection> {
 		}
 	}
 
+	@Override
+	public List<Byte> getSyncVersions(Connection txn, ContactId c)
+			throws DbException {
+		PreparedStatement ps = null;
+		ResultSet rs = null;
+		try {
+			String sql = "SELECT syncVersions FROM contacts"
+					+ " WHERE contactId = ?";
+			ps = txn.prepareStatement(sql);
+			ps.setInt(1, c.getInt());
+			rs = ps.executeQuery();
+			if (!rs.next()) throw new DbStateException();
+			byte[] bytes = rs.getBytes(1);
+			List<Byte> supported = new ArrayList<>(bytes.length);
+			for (byte b : bytes) supported.add(b);
+			if (rs.next()) throw new DbStateException();
+			rs.close();
+			ps.close();
+			return supported;
+		} catch (SQLException e) {
+			tryToClose(rs, LOG, WARNING);
+			tryToClose(ps, LOG, WARNING);
+			throw new DbException(e);
+		}
+	}
+
 	@Override
 	public Collection<TransportKeySet> getTransportKeys(Connection txn,
 			TransportId t) throws DbException {
@@ -2876,6 +2908,21 @@ abstract class JdbcDatabase implements Database<Connection> {
 		}
 	}
 
+	@Override
+	public void removeTemporaryMessages(Connection txn) throws DbException {
+		Statement s = null;
+		try {
+			String sql = "DELETE FROM messages WHERE temporary = TRUE";
+			s = txn.createStatement();
+			int affected = s.executeUpdate(sql);
+			if (affected < 0) throw new DbStateException();
+			s.close();
+		} catch (SQLException e) {
+			tryToClose(s, LOG, WARNING);
+			throw new DbException(e);
+		}
+	}
+
 	@Override
 	public void removeTransport(Connection txn, TransportId t)
 			throws DbException {
@@ -3021,6 +3068,24 @@ abstract class JdbcDatabase implements Database<Connection> {
 		}
 	}
 
+	@Override
+	public void setMessagePermanent(Connection txn, MessageId m)
+			throws DbException {
+		PreparedStatement ps = null;
+		try {
+			String sql = "UPDATE messages SET temporary = FALSE"
+					+ " WHERE messageId = ?";
+			ps = txn.prepareStatement(sql);
+			ps.setBytes(1, m.getBytes());
+			int affected = ps.executeUpdate();
+			if (affected < 0 || affected > 1) throw new DbStateException();
+			ps.close();
+		} catch (SQLException e) {
+			tryToClose(ps, LOG, WARNING);
+			throw new DbException(e);
+		}
+	}
+
 	@Override
 	public void setMessageShared(Connection txn, MessageId m)
 			throws DbException {
@@ -3124,6 +3189,29 @@ abstract class JdbcDatabase implements Database<Connection> {
 		}
 	}
 
+	@Override
+	public void setSyncVersions(Connection txn, ContactId c,
+			List<Byte> supported) throws DbException {
+		PreparedStatement ps = null;
+		try {
+			String sql = "UPDATE contacts SET syncVersions = ?"
+					+ " WHERE contactId = ?";
+			ps = txn.prepareStatement(sql);
+			byte[] bytes = new byte[supported.size()];
+			for (int i = 0; i < bytes.length; i++) {
+				bytes[i] = supported.get(i);
+			}
+			ps.setBytes(1, bytes);
+			ps.setInt(2, c.getInt());
+			int affected = ps.executeUpdate();
+			if (affected < 0 || affected > 1) throw new DbStateException();
+			ps.close();
+		} catch (SQLException e) {
+			tryToClose(ps, LOG, WARNING);
+			throw new DbException(e);
+		}
+	}
+
 	@Override
 	public void setTransportKeysActive(Connection txn, TransportId t,
 			KeySetId k) throws DbException {

bramble-core/src/main/java/org/briarproject/bramble/db/Migration45_46.java

@@ -0,0 +1,40 @@
+package org.briarproject.bramble.db;
+
+import org.briarproject.bramble.api.db.DbException;
+
+import java.sql.Connection;
+import java.sql.SQLException;
+import java.sql.Statement;
+import java.util.logging.Logger;
+
+import static java.util.logging.Level.WARNING;
+import static java.util.logging.Logger.getLogger;
+import static org.briarproject.bramble.db.JdbcUtils.tryToClose;
+
+class Migration45_46 implements Migration<Connection> {
+
+	private static final Logger LOG = getLogger(Migration45_46.class.getName());
+
+	@Override
+	public int getStartVersion() {
+		return 45;
+	}
+
+	@Override
+	public int getEndVersion() {
+		return 46;
+	}
+
+	@Override
+	public void migrate(Connection txn) throws DbException {
+		Statement s = null;
+		try {
+			s = txn.createStatement();
+			s.execute("ALTER TABLE messages"
+					+ " ADD COLUMN temporary BOOLEAN DEFAULT FALSE NOT NULL");
+		} catch (SQLException e) {
+			tryToClose(s, LOG, WARNING);
+			throw new DbException(e);
+		}
+	}
+}

bramble-core/src/main/java/org/briarproject/bramble/db/Migration46_47.java

@@ -0,0 +1,47 @@
+package org.briarproject.bramble.db;
+
+import org.briarproject.bramble.api.db.DbException;
+
+import java.sql.Connection;
+import java.sql.SQLException;
+import java.sql.Statement;
+import java.util.logging.Logger;
+
+import static java.util.logging.Level.WARNING;
+import static java.util.logging.Logger.getLogger;
+import static org.briarproject.bramble.db.JdbcUtils.tryToClose;
+
+class Migration46_47 implements Migration<Connection> {
+
+	private static final Logger LOG = getLogger(Migration46_47.class.getName());
+
+	private final DatabaseTypes dbTypes;
+
+	Migration46_47(DatabaseTypes dbTypes) {
+		this.dbTypes = dbTypes;
+	}
+
+	@Override
+	public int getStartVersion() {
+		return 46;
+	}
+
+	@Override
+	public int getEndVersion() {
+		return 47;
+	}
+
+	@Override
+	public void migrate(Connection txn) throws DbException {
+		Statement s = null;
+		try {
+			s = txn.createStatement();
+			s.execute(dbTypes.replaceTypes("ALTER TABLE contacts"
+					+ " ADD COLUMN syncVersions"
+					+ " _BINARY DEFAULT '00' NOT NULL"));
+		} catch (SQLException e) {
+			tryToClose(s, LOG, WARNING);
+			throw new DbException(e);
+		}
+	}
+}

bramble-core/src/main/java/org/briarproject/bramble/lifecycle/LifecycleManagerImpl.java

@@ -107,8 +107,11 @@ class LifecycleManagerImpl implements LifecycleManager, MigrationListener {
 			else logDuration(LOG, "Creating database", start);
 
 			db.transaction(false, txn -> {
+				long start1 = now();
+				db.removeTemporaryMessages(txn);
+				logDuration(LOG, "Removing temporary messages", start1);
 				for (OpenDatabaseHook hook : openDatabaseHooks) {
-					long start1 = now();
+					start1 = now();
 					hook.onDatabaseOpened(txn);
 					if (LOG.isLoggable(FINE)) {
 						logDuration(LOG, "Calling open database hook "

bramble-core/src/main/java/org/briarproject/bramble/properties/TransportPropertyManagerImpl.java

@@ -284,7 +284,7 @@ class TransportPropertyManagerImpl implements TransportPropertyManager,
 			meta.put("transportId", t.getString());
 			meta.put("version", version);
 			meta.put("local", local);
-			clientHelper.addLocalMessage(txn, m, meta, shared);
+			clientHelper.addLocalMessage(txn, m, meta, shared, false);
 		} catch (FormatException e) {
 			throw new RuntimeException(e);
 		}

bramble-core/src/main/java/org/briarproject/bramble/rendezvous/RendezvousPollerImpl.java

@@ -66,6 +66,7 @@ import static java.util.logging.Level.WARNING;
 import static java.util.logging.Logger.getLogger;
 import static org.briarproject.bramble.api.contact.PendingContactState.ADDING_CONTACT;
 import static org.briarproject.bramble.api.contact.PendingContactState.FAILED;
+import static org.briarproject.bramble.api.contact.PendingContactState.OFFLINE;
 import static org.briarproject.bramble.api.contact.PendingContactState.WAITING_FOR_CONNECTION;
 import static org.briarproject.bramble.api.nullsafety.NullSafety.requireNull;
 import static org.briarproject.bramble.rendezvous.RendezvousConstants.POLLING_INTERVAL_MS;
@@ -158,9 +159,7 @@ class RendezvousPollerImpl implements RendezvousPoller, Service, EventListener {
 	private void addPendingContact(PendingContact p) {
 		long now = clock.currentTimeMillis();
 		long expiry = p.getTimestamp() + RENDEZVOUS_TIMEOUT_MS;
-		if (expiry > now) {
+		if (expiry <= now) {
-			broadcastState(p.getId(), WAITING_FOR_CONNECTION);
-		} else {
 			broadcastState(p.getId(), FAILED);
 			return;
 		}
@@ -180,9 +179,13 @@ class RendezvousPollerImpl implements RendezvousPoller, Service, EventListener {
 			for (PluginState ps : pluginStates.values()) {
 				RendezvousEndpoint endpoint =
 						createEndpoint(ps.plugin, p.getId(), cs);
-				if (endpoint != null)
+				if (endpoint != null) {
 					requireNull(ps.endpoints.put(p.getId(), endpoint));
+					cs.numEndpoints++;
+				}
 			}
+			if (cs.numEndpoints == 0) broadcastState(p.getId(), OFFLINE);
+			else broadcastState(p.getId(), WAITING_FOR_CONNECTION);
 		} catch (DbException | GeneralSecurityException e) {
 			logException(LOG, WARNING, e);
 		}
@@ -328,9 +331,14 @@ class RendezvousPollerImpl implements RendezvousPoller, Service, EventListener {
 		TransportId t = plugin.getId();
 		Map<PendingContactId, RendezvousEndpoint> endpoints = new HashMap<>();
 		for (Entry<PendingContactId, CryptoState> e : cryptoStates.entrySet()) {
-			RendezvousEndpoint endpoint =
+			PendingContactId p = e.getKey();
-					createEndpoint(plugin, e.getKey(), e.getValue());
+			CryptoState cs = e.getValue();
-			if (endpoint != null) endpoints.put(e.getKey(), endpoint);
+			RendezvousEndpoint endpoint = createEndpoint(plugin, p, cs);
+			if (endpoint != null) {
+				endpoints.put(p, endpoint);
+				if (++cs.numEndpoints == 1)
+					broadcastState(p, WAITING_FOR_CONNECTION);
+			}
 		}
 		requireNull(pluginStates.put(t, new PluginState(plugin, endpoints)));
 	}
@@ -344,8 +352,11 @@ class RendezvousPollerImpl implements RendezvousPoller, Service, EventListener {
 	private void removeTransport(TransportId t) {
 		PluginState ps = pluginStates.remove(t);
 		if (ps != null) {
-			for (RendezvousEndpoint endpoint : ps.endpoints.values()) {
+			for (Entry<PendingContactId, RendezvousEndpoint> e :
-				tryToClose(endpoint, LOG, INFO);
+					ps.endpoints.entrySet()) {
+				tryToClose(e.getValue(), LOG, INFO);
+				CryptoState cs = cryptoStates.get(e.getKey());
+				if (--cs.numEndpoints == 0) broadcastState(e.getKey(), OFFLINE);
 			}
 		}
 	}
@@ -391,6 +402,8 @@ class RendezvousPollerImpl implements RendezvousPoller, Service, EventListener {
 		private final boolean alice;
 		private final long expiry;
 
+		private int numEndpoints = 0;
+
 		private CryptoState(SecretKey rendezvousKey, boolean alice,
 				long expiry) {
 			this.rendezvousKey = rendezvousKey;

bramble-core/src/main/java/org/briarproject/bramble/sync/DuplexOutgoingSession.java

@@ -17,6 +17,7 @@ import org.briarproject.bramble.api.sync.Offer;
 import org.briarproject.bramble.api.sync.Request;
 import org.briarproject.bramble.api.sync.SyncRecordWriter;
 import org.briarproject.bramble.api.sync.SyncSession;
+import org.briarproject.bramble.api.sync.Versions;
 import org.briarproject.bramble.api.sync.event.GroupVisibilityUpdatedEvent;
 import org.briarproject.bramble.api.sync.event.MessageRequestedEvent;
 import org.briarproject.bramble.api.sync.event.MessageSharedEvent;
@@ -39,9 +40,11 @@ import javax.annotation.concurrent.ThreadSafe;
 import static java.util.concurrent.TimeUnit.MILLISECONDS;
 import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
+import static java.util.logging.Logger.getLogger;
 import static org.briarproject.bramble.api.lifecycle.LifecycleManager.LifecycleState.STOPPING;
 import static org.briarproject.bramble.api.record.Record.MAX_RECORD_PAYLOAD_BYTES;
 import static org.briarproject.bramble.api.sync.SyncConstants.MAX_MESSAGE_IDS;
+import static org.briarproject.bramble.api.sync.SyncConstants.SUPPORTED_VERSIONS;
 import static org.briarproject.bramble.util.LogUtils.logException;
 
 /**
@@ -55,7 +58,7 @@ import static org.briarproject.bramble.util.LogUtils.logException;
 class DuplexOutgoingSession implements SyncSession, EventListener {
 
 	private static final Logger LOG =
-			Logger.getLogger(DuplexOutgoingSession.class.getName());
+			getLogger(DuplexOutgoingSession.class.getName());
 
 	private static final ThrowingRunnable<IOException> CLOSE = () -> {
 	};
@@ -103,6 +106,8 @@ class DuplexOutgoingSession implements SyncSession, EventListener {
 	public void run() throws IOException {
 		eventBus.addListener(this);
 		try {
+			// Send our supported protocol versions
+			recordWriter.writeVersions(new Versions(SUPPORTED_VERSIONS));
 			// Start a query for each type of record
 			generateAck();
 			generateBatch();

bramble-core/src/main/java/org/briarproject/bramble/sync/IncomingSession.java

@@ -18,14 +18,17 @@ import org.briarproject.bramble.api.sync.Offer;
 import org.briarproject.bramble.api.sync.Request;
 import org.briarproject.bramble.api.sync.SyncRecordReader;
 import org.briarproject.bramble.api.sync.SyncSession;
+import org.briarproject.bramble.api.sync.Versions;
 
 import java.io.IOException;
+import java.util.List;
 import java.util.concurrent.Executor;
 import java.util.logging.Logger;
 
 import javax.annotation.concurrent.ThreadSafe;
 
 import static java.util.logging.Level.WARNING;
+import static java.util.logging.Logger.getLogger;
 import static org.briarproject.bramble.api.lifecycle.LifecycleManager.LifecycleState.STOPPING;
 import static org.briarproject.bramble.util.LogUtils.logException;
 
@@ -37,7 +40,7 @@ import static org.briarproject.bramble.util.LogUtils.logException;
 class IncomingSession implements SyncSession, EventListener {
 
 	private static final Logger LOG =
-			Logger.getLogger(IncomingSession.class.getName());
+			getLogger(IncomingSession.class.getName());
 
 	private final DatabaseComponent db;
 	private final Executor dbExecutor;
@@ -80,6 +83,9 @@ class IncomingSession implements SyncSession, EventListener {
 				} else if (recordReader.hasRequest()) {
 					Request r = recordReader.readRequest();
 					dbExecutor.execute(new ReceiveRequest(r));
+				} else if (recordReader.hasVersions()) {
+					Versions v = recordReader.readVersions();
+					dbExecutor.execute(new ReceiveVersions(v));
 				} else {
 					// unknown records are ignored in RecordReader#eof()
 					throw new FormatException();
@@ -190,4 +196,26 @@ class IncomingSession implements SyncSession, EventListener {
 			}
 		}
 	}
+
+	private class ReceiveVersions implements Runnable {
+
+		private final Versions versions;
+
+		private ReceiveVersions(Versions versions) {
+			this.versions = versions;
+		}
+
+		@DatabaseExecutor
+		@Override
+		public void run() {
+			try {
+				List<Byte> supported = versions.getSupportedVersions();
+				db.transaction(false,
+						txn -> db.setSyncVersions(txn, contactId, supported));
+			} catch (DbException e) {
+				logException(LOG, WARNING, e);
+				interrupt();
+			}
+		}
+	}
 }

bramble-core/src/main/java/org/briarproject/bramble/sync/SimplexOutgoingSession.java

@@ -15,6 +15,7 @@ import org.briarproject.bramble.api.sync.Ack;
 import org.briarproject.bramble.api.sync.Message;
 import org.briarproject.bramble.api.sync.SyncRecordWriter;
 import org.briarproject.bramble.api.sync.SyncSession;
+import org.briarproject.bramble.api.sync.Versions;
 import org.briarproject.bramble.api.transport.StreamWriter;
 
 import java.io.IOException;
@@ -29,9 +30,11 @@ import javax.annotation.concurrent.ThreadSafe;
 
 import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
+import static java.util.logging.Logger.getLogger;
 import static org.briarproject.bramble.api.lifecycle.LifecycleManager.LifecycleState.STOPPING;
 import static org.briarproject.bramble.api.record.Record.MAX_RECORD_PAYLOAD_BYTES;
 import static org.briarproject.bramble.api.sync.SyncConstants.MAX_MESSAGE_IDS;
+import static org.briarproject.bramble.api.sync.SyncConstants.SUPPORTED_VERSIONS;
 import static org.briarproject.bramble.util.LogUtils.logException;
 
 /**
@@ -44,7 +47,7 @@ import static org.briarproject.bramble.util.LogUtils.logException;
 class SimplexOutgoingSession implements SyncSession, EventListener {
 
 	private static final Logger LOG =
-			Logger.getLogger(SimplexOutgoingSession.class.getName());
+			getLogger(SimplexOutgoingSession.class.getName());
 
 	private static final ThrowingRunnable<IOException> CLOSE = () -> {
 	};
@@ -80,6 +83,8 @@ class SimplexOutgoingSession implements SyncSession, EventListener {
 	public void run() throws IOException {
 		eventBus.addListener(this);
 		try {
+			// Send our supported protocol versions
+			recordWriter.writeVersions(new Versions(SUPPORTED_VERSIONS));
 			// Start a query for each type of record
 			dbExecutor.execute(new GenerateAck());
 			dbExecutor.execute(new GenerateBatch());

bramble-core/src/main/java/org/briarproject/bramble/sync/SyncRecordReaderImpl.java

@@ -13,6 +13,7 @@ import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.bramble.api.sync.Offer;
 import org.briarproject.bramble.api.sync.Request;
 import org.briarproject.bramble.api.sync.SyncRecordReader;
+import org.briarproject.bramble.api.sync.Versions;
 import org.briarproject.bramble.util.ByteUtils;
 
 import java.io.IOException;
@@ -26,6 +27,8 @@ import static org.briarproject.bramble.api.sync.RecordTypes.ACK;
 import static org.briarproject.bramble.api.sync.RecordTypes.MESSAGE;
 import static org.briarproject.bramble.api.sync.RecordTypes.OFFER;
 import static org.briarproject.bramble.api.sync.RecordTypes.REQUEST;
+import static org.briarproject.bramble.api.sync.RecordTypes.VERSIONS;
+import static org.briarproject.bramble.api.sync.SyncConstants.MAX_SUPPORTED_VERSIONS;
 import static org.briarproject.bramble.api.sync.SyncConstants.MESSAGE_HEADER_LENGTH;
 import static org.briarproject.bramble.api.sync.SyncConstants.PROTOCOL_VERSION;
 
@@ -45,7 +48,7 @@ class SyncRecordReaderImpl implements SyncRecordReader {
 
 	private static boolean isKnownRecordType(byte type) {
 		return type == ACK || type == MESSAGE || type == OFFER ||
-				type == REQUEST;
+				type == REQUEST || type == VERSIONS;
 	}
 
 	private final MessageFactory messageFactory;
@@ -148,4 +151,27 @@ class SyncRecordReaderImpl implements SyncRecordReader {
 		if (!hasRequest()) throw new FormatException();
 		return new Request(readMessageIds());
 	}
+
+	@Override
+	public boolean hasVersions() throws IOException {
+		return !eof() && getNextRecordType() == VERSIONS;
+	}
+
+	@Override
+	public Versions readVersions() throws IOException {
+		if (!hasVersions()) throw new FormatException();
+		return new Versions(readSupportedVersions());
+	}
+
+	private List<Byte> readSupportedVersions() throws IOException {
+		if (nextRecord == null) throw new AssertionError();
+		byte[] payload = nextRecord.getPayload();
+		if (payload.length == 0) throw new FormatException();
+		if (payload.length > MAX_SUPPORTED_VERSIONS)
+			throw new FormatException();
+		List<Byte> supported = new ArrayList<>(payload.length);
+		for (byte b : payload) supported.add(b);
+		nextRecord = null;
+		return supported;
+	}
 }

bramble-core/src/main/java/org/briarproject/bramble/sync/SyncRecordWriterImpl.java

@@ -10,6 +10,7 @@ import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.bramble.api.sync.Offer;
 import org.briarproject.bramble.api.sync.Request;
 import org.briarproject.bramble.api.sync.SyncRecordWriter;
+import org.briarproject.bramble.api.sync.Versions;
 
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
@@ -20,6 +21,7 @@ import static org.briarproject.bramble.api.sync.RecordTypes.ACK;
 import static org.briarproject.bramble.api.sync.RecordTypes.MESSAGE;
 import static org.briarproject.bramble.api.sync.RecordTypes.OFFER;
 import static org.briarproject.bramble.api.sync.RecordTypes.REQUEST;
+import static org.briarproject.bramble.api.sync.RecordTypes.VERSIONS;
 import static org.briarproject.bramble.api.sync.SyncConstants.PROTOCOL_VERSION;
 
 @NotThreadSafe
@@ -65,6 +67,12 @@ class SyncRecordWriterImpl implements SyncRecordWriter {
 		writeRecord(REQUEST);
 	}
 
+	@Override
+	public void writeVersions(Versions v) throws IOException {
+		for (byte b : v.getSupportedVersions()) payload.write(b);
+		writeRecord(VERSIONS);
+	}
+
 	@Override
 	public void flush() throws IOException {
 		writer.flush();

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

@@ -314,6 +314,7 @@ class ValidationManagerImpl implements ValidationManager, Service,
 			try {
 				shareMsg = hook.incomingMessage(txn, m, meta);
 			} catch (InvalidMessageException e) {
+				logException(LOG, INFO, e);
 				invalidateMessage(txn, m.getId());
 				return new DeliveryResult(false, false);
 			}

bramble-core/src/main/java/org/briarproject/bramble/versioning/ClientVersioningManagerImpl.java

@@ -243,7 +243,7 @@ class ClientVersioningManagerImpl implements ClientVersioningManager,
 		try {
 			Message m = clientHelper.createMessage(localGroup.getId(), now,
 					body);
-			db.addLocalMessage(txn, m, new Metadata(), false);
+			db.addLocalMessage(txn, m, new Metadata(), false, false);
 		} catch (FormatException e) {
 			throw new AssertionError(e);
 		}
@@ -438,7 +438,7 @@ class ClientVersioningManagerImpl implements ClientVersioningManager,
 			BdfDictionary meta = new BdfDictionary();
 			meta.put(MSG_KEY_UPDATE_VERSION, updateVersion);
 			meta.put(MSG_KEY_LOCAL, true);
-			clientHelper.addLocalMessage(txn, m, meta, true);
+			clientHelper.addLocalMessage(txn, m, meta, true, false);
 		} catch (FormatException e) {
 			throw new RuntimeException(e);
 		}

bramble-core/src/test/java/org/briarproject/bramble/client/ClientHelperImplTest.java

@@ -96,7 +96,7 @@ public class ClientHelperImplTest extends BrambleTestCase {
 			oneOf(db).transaction(with(false), withDbRunnable(txn));
 			oneOf(metadataEncoder).encode(dictionary);
 			will(returnValue(metadata));
-			oneOf(db).addLocalMessage(txn, message, metadata, shared);
+			oneOf(db).addLocalMessage(txn, message, metadata, shared, false);
 		}});
 
 		clientHelper.addLocalMessage(message, dictionary, shared);

bramble-core/src/test/java/org/briarproject/bramble/contact/ContactExchangeIntegrationTest.java

@@ -6,11 +6,15 @@ import org.briarproject.bramble.api.contact.ContactManager;
 import org.briarproject.bramble.api.contact.PendingContact;
 import org.briarproject.bramble.api.contact.PendingContactState;
 import org.briarproject.bramble.api.contact.event.ContactAddedEvent;
+import org.briarproject.bramble.api.contact.event.PendingContactStateChangedEvent;
 import org.briarproject.bramble.api.crypto.PublicKey;
 import org.briarproject.bramble.api.crypto.SecretKey;
+import org.briarproject.bramble.api.event.Event;
+import org.briarproject.bramble.api.event.EventListener;
 import org.briarproject.bramble.api.identity.Identity;
 import org.briarproject.bramble.api.identity.IdentityManager;
 import org.briarproject.bramble.api.lifecycle.LifecycleManager;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.test.BrambleTestCase;
 import org.briarproject.bramble.test.TestDatabaseConfigModule;
 import org.briarproject.bramble.test.TestDuplexTransportConnection;
@@ -27,7 +31,7 @@ import static java.util.concurrent.TimeUnit.MILLISECONDS;
 import static junit.framework.TestCase.assertNotNull;
 import static junit.framework.TestCase.assertNull;
 import static junit.framework.TestCase.fail;
-import static org.briarproject.bramble.api.contact.PendingContactState.WAITING_FOR_CONNECTION;
+import static org.briarproject.bramble.api.contact.PendingContactState.OFFLINE;
 import static org.briarproject.bramble.test.TestDuplexTransportConnection.createPair;
 import static org.briarproject.bramble.test.TestPluginConfigModule.DUPLEX_TRANSPORT_ID;
 import static org.briarproject.bramble.test.TestUtils.deleteTestDirectory;
@@ -188,9 +192,14 @@ public class ContactExchangeIntegrationTest extends BrambleTestCase {
 	private PendingContact addPendingContact(
 			ContactExchangeIntegrationTestComponent local,
 			ContactExchangeIntegrationTestComponent remote) throws Exception {
+		EventWaiter waiter = new EventWaiter();
+		local.getEventBus().addListener(waiter);
 		String link = remote.getContactManager().getHandshakeLink();
 		String alias = remote.getIdentityManager().getLocalAuthor().getName();
-		return local.getContactManager().addPendingContact(link, alias);
+		PendingContact pendingContact =
+				local.getContactManager().addPendingContact(link, alias);
+		waiter.latch.await(TIMEOUT, MILLISECONDS);
+		return pendingContact;
 	}
 
 	private void assertContacts(boolean verified,
@@ -237,7 +246,7 @@ public class ContactExchangeIntegrationTest extends BrambleTestCase {
 		assertEquals(1, pairs.size());
 		Pair<PendingContact, PendingContactState> pair =
 				pairs.iterator().next();
-		assertEquals(WAITING_FOR_CONNECTION, pair.getSecond());
+		assertEquals(OFFLINE, pair.getSecond());
 		PendingContact pendingContact = pair.getFirst();
 		assertEquals(expectedIdentity.getLocalAuthor().getName(),
 				pendingContact.getAlias());
@@ -261,4 +270,19 @@ public class ContactExchangeIntegrationTest extends BrambleTestCase {
 		tearDown(bob);
 		deleteTestDirectory(testDir);
 	}
+
+	@NotNullByDefault
+	private static class EventWaiter implements EventListener {
+
+		private final CountDownLatch latch = new CountDownLatch(1);
+
+		@Override
+		public void eventOccurred(Event e) {
+			if (e instanceof PendingContactStateChangedEvent) {
+				PendingContactStateChangedEvent p =
+						(PendingContactStateChangedEvent) e;
+				if (p.getPendingContactState() == OFFLINE) latch.countDown();
+			}
+		}
+	}
 }

bramble-core/src/test/java/org/briarproject/bramble/db/DatabaseComponentImplTest.java

@@ -61,10 +61,12 @@ import org.junit.Test;
 
 import java.util.ArrayList;
 import java.util.Collection;
+import java.util.Random;
 import java.util.concurrent.Executor;
 import java.util.concurrent.atomic.AtomicReference;
 
 import static java.util.Arrays.asList;
+import static java.util.Collections.emptyList;
 import static java.util.Collections.emptyMap;
 import static java.util.Collections.singletonList;
 import static org.briarproject.bramble.api.sync.Group.Visibility.INVISIBLE;
@@ -120,6 +122,9 @@ public class DatabaseComponentImplTest extends BrambleMockTestCase {
 	private final Contact contact;
 	private final KeySetId keySetId;
 	private final PendingContactId pendingContactId;
+	private final Random random = new Random();
+	private final boolean shared = random.nextBoolean();
+	private final boolean temporary = random.nextBoolean();
 
 	public DatabaseComponentImplTest() {
 		clientId = getClientId();
@@ -253,7 +258,8 @@ public class DatabaseComponentImplTest extends BrambleMockTestCase {
 				eventExecutor, shutdownManager);
 
 		db.transaction(false, transaction ->
-				db.addLocalMessage(transaction, message, metadata, true));
+				db.addLocalMessage(transaction, message, metadata, shared,
+						temporary));
 	}
 
 	@Test
@@ -265,20 +271,23 @@ public class DatabaseComponentImplTest extends BrambleMockTestCase {
 			will(returnValue(true));
 			oneOf(database).containsMessage(txn, messageId);
 			will(returnValue(false));
-			oneOf(database).addMessage(txn, message, DELIVERED, true, null);
+			oneOf(database).addMessage(txn, message, DELIVERED, shared,
+					temporary, null);
 			oneOf(database).mergeMessageMetadata(txn, messageId, metadata);
 			oneOf(database).commitTransaction(txn);
 			// The message was added, so the listeners should be called
 			oneOf(eventBus).broadcast(with(any(MessageAddedEvent.class)));
-			oneOf(eventBus)
+			oneOf(eventBus).broadcast(with(any(
-					.broadcast(with(any(MessageStateChangedEvent.class)));
+					MessageStateChangedEvent.class)));
-			oneOf(eventBus).broadcast(with(any(MessageSharedEvent.class)));
+			if (shared)
+				oneOf(eventBus).broadcast(with(any(MessageSharedEvent.class)));
 		}});
 		DatabaseComponent db = createDatabaseComponent(database, eventBus,
 				eventExecutor, shutdownManager);
 
 		db.transaction(false, transaction ->
-				db.addLocalMessage(transaction, message, metadata, true));
+				db.addLocalMessage(transaction, message, metadata, shared,
+						temporary));
 	}
 
 	@Test
@@ -286,11 +295,11 @@ public class DatabaseComponentImplTest extends BrambleMockTestCase {
 			throws Exception {
 		context.checking(new Expectations() {{
 			// Check whether the contact is in the DB (which it's not)
-			exactly(16).of(database).startTransaction();
+			exactly(18).of(database).startTransaction();
 			will(returnValue(txn));
-			exactly(16).of(database).containsContact(txn, contactId);
+			exactly(18).of(database).containsContact(txn, contactId);
 			will(returnValue(false));
-			exactly(16).of(database).abortTransaction(txn);
+			exactly(18).of(database).abortTransaction(txn);
 		}});
 		DatabaseComponent db = createDatabaseComponent(database, eventBus,
 				eventExecutor, shutdownManager);
@@ -368,6 +377,14 @@ public class DatabaseComponentImplTest extends BrambleMockTestCase {
 			// Expected
 		}
 
+		try {
+			db.transaction(false, transaction ->
+					db.getSyncVersions(transaction, contactId));
+			fail();
+		} catch (NoSuchContactException expected) {
+			// Expected
+		}
+
 		try {
 			Ack a = new Ack(singletonList(messageId));
 			db.transaction(false, transaction ->
@@ -427,6 +444,14 @@ public class DatabaseComponentImplTest extends BrambleMockTestCase {
 		} catch (NoSuchContactException expected) {
 			// Expected
 		}
+
+		try {
+			db.transaction(false, transaction ->
+					db.setSyncVersions(transaction, contactId, emptyList()));
+			fail();
+		} catch (NoSuchContactException expected) {
+			// Expected
+		}
 	}
 
 	@Test
@@ -569,11 +594,11 @@ public class DatabaseComponentImplTest extends BrambleMockTestCase {
 			throws Exception {
 		context.checking(new Expectations() {{
 			// Check whether the message is in the DB (which it's not)
-			exactly(11).of(database).startTransaction();
+			exactly(12).of(database).startTransaction();
 			will(returnValue(txn));
-			exactly(11).of(database).containsMessage(txn, messageId);
+			exactly(12).of(database).containsMessage(txn, messageId);
 			will(returnValue(false));
-			exactly(11).of(database).abortTransaction(txn);
+			exactly(12).of(database).abortTransaction(txn);
 			// Allow other checks to pass
 			allowing(database).containsContact(txn, contactId);
 			will(returnValue(true));
@@ -637,6 +662,14 @@ public class DatabaseComponentImplTest extends BrambleMockTestCase {
 			// Expected
 		}
 
+		try {
+			db.transaction(false, transaction ->
+					db.setMessagePermanent(transaction, message.getId()));
+			fail();
+		} catch (NoSuchMessageException expected) {
+			// Expected
+		}
+
 		try {
 			db.transaction(false, transaction ->
 					db.setMessageShared(transaction, message.getId()));
@@ -972,7 +1005,8 @@ public class DatabaseComponentImplTest extends BrambleMockTestCase {
 			will(returnValue(VISIBLE));
 			oneOf(database).containsMessage(txn, messageId);
 			will(returnValue(false));
-			oneOf(database).addMessage(txn, message, UNKNOWN, false, contactId);
+			oneOf(database).addMessage(txn, message, UNKNOWN, false, false,
+					contactId);
 			// Second time
 			oneOf(database).containsContact(txn, contactId);
 			will(returnValue(true));
@@ -1507,6 +1541,7 @@ public class DatabaseComponentImplTest extends BrambleMockTestCase {
 	public void testMessageDependencies() throws Exception {
 		int shutdownHandle = 12345;
 		MessageId messageId2 = new MessageId(getRandomId());
+
 		context.checking(new Expectations() {{
 			// open()
 			oneOf(database).open(key, null);
@@ -1521,7 +1556,8 @@ public class DatabaseComponentImplTest extends BrambleMockTestCase {
 			will(returnValue(true));
 			oneOf(database).containsMessage(txn, messageId);
 			will(returnValue(false));
-			oneOf(database).addMessage(txn, message, DELIVERED, true, null);
+			oneOf(database).addMessage(txn, message, DELIVERED, shared,
+					temporary, null);
 			oneOf(database).mergeMessageMetadata(txn, messageId, metadata);
 			// addMessageDependencies()
 			oneOf(database).containsMessage(txn, messageId);
@@ -1544,7 +1580,8 @@ public class DatabaseComponentImplTest extends BrambleMockTestCase {
 			oneOf(eventBus).broadcast(with(any(MessageAddedEvent.class)));
 			oneOf(eventBus).broadcast(with(any(
 					MessageStateChangedEvent.class)));
-			oneOf(eventBus).broadcast(with(any(MessageSharedEvent.class)));
+			if (shared)
+				oneOf(eventBus).broadcast(with(any(MessageSharedEvent.class)));
 			// endTransaction()
 			oneOf(database).commitTransaction(txn);
 			// close()
@@ -1555,7 +1592,8 @@ public class DatabaseComponentImplTest extends BrambleMockTestCase {
 
 		assertFalse(db.open(key, null));
 		db.transaction(false, transaction -> {
-			db.addLocalMessage(transaction, message, metadata, true);
+			db.addLocalMessage(transaction, message, metadata, shared,
+					temporary);
 			Collection<MessageId> dependencies = new ArrayList<>(2);
 			dependencies.add(messageId1);
 			dependencies.add(messageId2);

bramble-core/src/test/java/org/briarproject/bramble/db/DatabasePerformanceTest.java

@@ -567,8 +567,9 @@ public abstract class DatabasePerformanceTest extends BrambleTestCase {
 					MessageState state =
 							MessageState.fromValue(random.nextInt(4));
 					boolean shared = random.nextBoolean();
+					boolean temporary = random.nextBoolean();
 					ContactId sender = random.nextBoolean() ? c : null;
-					db.addMessage(txn, m, state, shared, sender);
+					db.addMessage(txn, m, state, shared, temporary, sender);
 					if (random.nextBoolean())
 						db.raiseRequestedFlag(txn, c, m.getId());
 					Metadata mm = getMetadata(METADATA_KEYS_PER_MESSAGE);
@@ -597,7 +598,8 @@ public abstract class DatabasePerformanceTest extends BrambleTestCase {
 			for (int j = 0; j < MESSAGES_PER_GROUP; j++) {
 				Message m = getMessage(g.getId());
 				messages.add(m);
-				db.addMessage(txn, m, DELIVERED, false, null);
+				boolean temporary = random.nextBoolean();
+				db.addMessage(txn, m, DELIVERED, false, temporary, null);
 				Metadata mm = getMetadata(METADATA_KEYS_PER_MESSAGE);
 				messageMeta.get(g.getId()).add(mm);
 				db.mergeMessageMetadata(txn, m.getId(), mm);

bramble-core/src/test/java/org/briarproject/bramble/db/JdbcDatabaseTest.java

@@ -41,7 +41,6 @@ import org.junit.Test;
 import java.io.File;
 import java.sql.Connection;
 import java.util.ArrayList;
-import java.util.Arrays;
 import java.util.Collection;
 import java.util.List;
 import java.util.Map;
@@ -51,6 +50,7 @@ import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicLong;
 
+import static java.util.Arrays.asList;
 import static java.util.Collections.emptyList;
 import static java.util.Collections.emptyMap;
 import static java.util.Collections.singletonList;
@@ -153,7 +153,7 @@ public abstract class JdbcDatabaseTest extends BrambleTestCase {
 		db.addGroup(txn, group);
 		assertTrue(db.containsGroup(txn, groupId));
 		assertFalse(db.containsMessage(txn, messageId));
-		db.addMessage(txn, message, DELIVERED, true, null);
+		db.addMessage(txn, message, DELIVERED, true, false, null);
 		assertTrue(db.containsMessage(txn, messageId));
 		db.commitTransaction(txn);
 		db.close();
@@ -191,7 +191,7 @@ public abstract class JdbcDatabaseTest extends BrambleTestCase {
 
 		// Add a group and a message
 		db.addGroup(txn, group);
-		db.addMessage(txn, message, DELIVERED, true, null);
+		db.addMessage(txn, message, DELIVERED, true, false, null);
 
 		// Removing the group should remove the message
 		assertTrue(db.containsMessage(txn, messageId));
@@ -213,7 +213,7 @@ public abstract class JdbcDatabaseTest extends BrambleTestCase {
 				db.addContact(txn, author, localAuthor.getId(), null, true));
 		db.addGroup(txn, group);
 		db.addGroupVisibility(txn, contactId, groupId, true);
-		db.addMessage(txn, message, DELIVERED, true, null);
+		db.addMessage(txn, message, DELIVERED, true, false, null);
 
 		// The contact has not seen the message, so it should be sendable
 		Collection<MessageId> ids =
@@ -244,7 +244,7 @@ public abstract class JdbcDatabaseTest extends BrambleTestCase {
 				db.addContact(txn, author, localAuthor.getId(), null, true));
 		db.addGroup(txn, group);
 		db.addGroupVisibility(txn, contactId, groupId, true);
-		db.addMessage(txn, message, UNKNOWN, true, null);
+		db.addMessage(txn, message, UNKNOWN, true, false, null);
 
 		// The message has not been validated, so it should not be sendable
 		Collection<MessageId> ids = db.getMessagesToSend(txn, contactId,
@@ -288,7 +288,7 @@ public abstract class JdbcDatabaseTest extends BrambleTestCase {
 		assertEquals(contactId,
 				db.addContact(txn, author, localAuthor.getId(), null, true));
 		db.addGroup(txn, group);
-		db.addMessage(txn, message, DELIVERED, true, null);
+		db.addMessage(txn, message, DELIVERED, true, false, null);
 
 		// The group is invisible, so the message should not be sendable
 		Collection<MessageId> ids = db.getMessagesToSend(txn, contactId,
@@ -340,7 +340,7 @@ public abstract class JdbcDatabaseTest extends BrambleTestCase {
 				db.addContact(txn, author, localAuthor.getId(), null, true));
 		db.addGroup(txn, group);
 		db.addGroupVisibility(txn, contactId, groupId, true);
-		db.addMessage(txn, message, DELIVERED, false, null);
+		db.addMessage(txn, message, DELIVERED, false, false, null);
 
 		// The message is not shared, so it should not be sendable
 		Collection<MessageId> ids = db.getMessagesToSend(txn, contactId,
@@ -371,7 +371,7 @@ public abstract class JdbcDatabaseTest extends BrambleTestCase {
 				db.addContact(txn, author, localAuthor.getId(), null, true));
 		db.addGroup(txn, group);
 		db.addGroupVisibility(txn, contactId, groupId, true);
-		db.addMessage(txn, message, DELIVERED, true, null);
+		db.addMessage(txn, message, DELIVERED, true, false, null);
 
 		// The message is sendable, but too large to send
 		Collection<MessageId> ids =
@@ -402,15 +402,15 @@ public abstract class JdbcDatabaseTest extends BrambleTestCase {
 		// Add some messages to ack
 		Message message1 = getMessage(groupId);
 		MessageId messageId1 = message1.getId();
-		db.addMessage(txn, message, DELIVERED, true, contactId);
+		db.addMessage(txn, message, DELIVERED, true, false, contactId);
-		db.addMessage(txn, message1, DELIVERED, true, contactId);
+		db.addMessage(txn, message1, DELIVERED, true, false, contactId);
 
 		// Both message IDs should be returned
 		Collection<MessageId> ids = db.getMessagesToAck(txn, contactId, 1234);
-		assertEquals(Arrays.asList(messageId, messageId1), ids);
+		assertEquals(asList(messageId, messageId1), ids);
 
 		// Remove both message IDs
-		db.lowerAckFlag(txn, contactId, Arrays.asList(messageId, messageId1));
+		db.lowerAckFlag(txn, contactId, asList(messageId, messageId1));
 
 		// Both message IDs should have been removed
 		assertEquals(emptyList(), db.getMessagesToAck(txn,
@@ -422,7 +422,7 @@ public abstract class JdbcDatabaseTest extends BrambleTestCase {
 
 		// Both message IDs should be returned
 		ids = db.getMessagesToAck(txn, contactId, 1234);
-		assertEquals(Arrays.asList(messageId, messageId1), ids);
+		assertEquals(asList(messageId, messageId1), ids);
 
 		db.commitTransaction(txn);
 		db.close();
@@ -439,7 +439,7 @@ public abstract class JdbcDatabaseTest extends BrambleTestCase {
 				db.addContact(txn, author, localAuthor.getId(), null, true));
 		db.addGroup(txn, group);
 		db.addGroupVisibility(txn, contactId, groupId, true);
-		db.addMessage(txn, message, DELIVERED, true, null);
+		db.addMessage(txn, message, DELIVERED, true, false, null);
 
 		// Retrieve the message from the database and mark it as sent
 		Collection<MessageId> ids = db.getMessagesToSend(txn, contactId,
@@ -608,7 +608,7 @@ public abstract class JdbcDatabaseTest extends BrambleTestCase {
 		assertEquals(contactId,
 				db.addContact(txn, author, localAuthor.getId(), null, true));
 		db.addGroup(txn, group);
-		db.addMessage(txn, message, DELIVERED, true, null);
+		db.addMessage(txn, message, DELIVERED, true, false, null);
 
 		// The group is not visible so the message should not be visible
 		assertFalse(db.containsVisibleMessage(txn, contactId, messageId));
@@ -1223,7 +1223,7 @@ public abstract class JdbcDatabaseTest extends BrambleTestCase {
 
 		// Add a group and a message
 		db.addGroup(txn, group);
-		db.addMessage(txn, message, DELIVERED, true, null);
+		db.addMessage(txn, message, DELIVERED, true, false, null);
 
 		// Attach some metadata to the message
 		Metadata metadata = new Metadata();
@@ -1294,7 +1294,7 @@ public abstract class JdbcDatabaseTest extends BrambleTestCase {
 
 		// Add a group and a message
 		db.addGroup(txn, group);
-		db.addMessage(txn, message, DELIVERED, true, null);
+		db.addMessage(txn, message, DELIVERED, true, false, null);
 
 		// Attach some metadata to the message
 		Metadata metadata = new Metadata();
@@ -1355,8 +1355,8 @@ public abstract class JdbcDatabaseTest extends BrambleTestCase {
 
 		// Add a group and two messages
 		db.addGroup(txn, group);
-		db.addMessage(txn, message, DELIVERED, true, null);
+		db.addMessage(txn, message, DELIVERED, true, false, null);
-		db.addMessage(txn, message1, DELIVERED, true, null);
+		db.addMessage(txn, message1, DELIVERED, true, false, null);
 
 		// Attach some metadata to the messages
 		Metadata metadata = new Metadata();
@@ -1459,8 +1459,8 @@ public abstract class JdbcDatabaseTest extends BrambleTestCase {
 
 		// Add a group and two messages
 		db.addGroup(txn, group);
-		db.addMessage(txn, message, DELIVERED, true, null);
+		db.addMessage(txn, message, DELIVERED, true, false, null);
-		db.addMessage(txn, message1, DELIVERED, true, null);
+		db.addMessage(txn, message1, DELIVERED, true, false, null);
 
 		// Attach some metadata to the messages
 		Metadata metadata = new Metadata();
@@ -1536,9 +1536,9 @@ public abstract class JdbcDatabaseTest extends BrambleTestCase {
 
 		// Add a group and some messages
 		db.addGroup(txn, group);
-		db.addMessage(txn, message, PENDING, true, contactId);
+		db.addMessage(txn, message, PENDING, true, false, contactId);
-		db.addMessage(txn, message1, PENDING, true, contactId);
+		db.addMessage(txn, message1, PENDING, true, false, contactId);
-		db.addMessage(txn, message2, INVALID, true, contactId);
+		db.addMessage(txn, message2, INVALID, true, false, contactId);
 
 		// Add dependencies
 		db.addMessageDependency(txn, message, messageId1, PENDING);
@@ -1589,7 +1589,7 @@ public abstract class JdbcDatabaseTest extends BrambleTestCase {
 		assertEquals(0, dependents.size());
 
 		// Add message 3
-		db.addMessage(txn, message3, UNKNOWN, false, contactId);
+		db.addMessage(txn, message3, UNKNOWN, false, false, contactId);
 
 		// Message 3 has message 1 as a dependent
 		dependents = db.getMessageDependents(txn, messageId3);
@@ -1601,7 +1601,7 @@ public abstract class JdbcDatabaseTest extends BrambleTestCase {
 		assertEquals(0, dependents.size());
 
 		// Add message 4
-		db.addMessage(txn, message4, UNKNOWN, false, contactId);
+		db.addMessage(txn, message4, UNKNOWN, false, false, contactId);
 
 		// Message 4 has message 2 as a dependent
 		dependents = db.getMessageDependents(txn, messageId4);
@@ -1619,7 +1619,7 @@ public abstract class JdbcDatabaseTest extends BrambleTestCase {
 
 		// Add a group and a message
 		db.addGroup(txn, group);
-		db.addMessage(txn, message, PENDING, true, contactId);
+		db.addMessage(txn, message, PENDING, true, false, contactId);
 
 		// Add a second group
 		Group group1 = getGroup(clientId, 123);
@@ -1629,7 +1629,7 @@ public abstract class JdbcDatabaseTest extends BrambleTestCase {
 		// Add a message to the second group
 		Message message1 = getMessage(groupId1);
 		MessageId messageId1 = message1.getId();
-		db.addMessage(txn, message1, DELIVERED, true, contactId);
+		db.addMessage(txn, message1, DELIVERED, true, false, contactId);
 
 		// Create an ID for a missing message
 		MessageId messageId2 = new MessageId(getRandomId());
@@ -1637,7 +1637,7 @@ public abstract class JdbcDatabaseTest extends BrambleTestCase {
 		// Add another message to the first group
 		Message message3 = getMessage(groupId);
 		MessageId messageId3 = message3.getId();
-		db.addMessage(txn, message3, DELIVERED, true, contactId);
+		db.addMessage(txn, message3, DELIVERED, true, false, contactId);
 
 		// Add dependencies between the messages
 		db.addMessageDependency(txn, message, messageId1, PENDING);
@@ -1680,10 +1680,10 @@ public abstract class JdbcDatabaseTest extends BrambleTestCase {
 
 		// Add a group and some messages with different states
 		db.addGroup(txn, group);
-		db.addMessage(txn, message1, UNKNOWN, true, contactId);
+		db.addMessage(txn, message1, UNKNOWN, true, false, contactId);
-		db.addMessage(txn, message2, INVALID, true, contactId);
+		db.addMessage(txn, message2, INVALID, true, false, contactId);
-		db.addMessage(txn, message3, PENDING, true, contactId);
+		db.addMessage(txn, message3, PENDING, true, false, contactId);
-		db.addMessage(txn, message4, DELIVERED, true, contactId);
+		db.addMessage(txn, message4, DELIVERED, true, false, contactId);
 
 		Collection<MessageId> result;
 
@@ -1713,10 +1713,10 @@ public abstract class JdbcDatabaseTest extends BrambleTestCase {
 
 		// Add a group and some messages
 		db.addGroup(txn, group);
-		db.addMessage(txn, message1, DELIVERED, true, contactId);
+		db.addMessage(txn, message1, DELIVERED, true, false, contactId);
-		db.addMessage(txn, message2, DELIVERED, false, contactId);
+		db.addMessage(txn, message2, DELIVERED, false, false, contactId);
-		db.addMessage(txn, message3, DELIVERED, false, contactId);
+		db.addMessage(txn, message3, DELIVERED, false, false, contactId);
-		db.addMessage(txn, message4, DELIVERED, true, contactId);
+		db.addMessage(txn, message4, DELIVERED, true, false, contactId);
 
 		// Introduce dependencies between the messages
 		db.addMessageDependency(txn, message1, message2.getId(), DELIVERED);
@@ -1744,7 +1744,7 @@ public abstract class JdbcDatabaseTest extends BrambleTestCase {
 				db.addContact(txn, author, localAuthor.getId(), null, true));
 		db.addGroup(txn, group);
 		db.addGroupVisibility(txn, contactId, groupId, true);
-		db.addMessage(txn, message, DELIVERED, true, null);
+		db.addMessage(txn, message, DELIVERED, true, false, null);
 
 		// The message should not be sent or seen
 		MessageStatus status = db.getMessageStatus(txn, contactId, messageId);
@@ -1878,7 +1878,7 @@ public abstract class JdbcDatabaseTest extends BrambleTestCase {
 				db.addContact(txn, author, localAuthor.getId(), null, true));
 		db.addGroup(txn, group);
 		db.addGroupVisibility(txn, contactId, groupId, true);
-		db.addMessage(txn, message, DELIVERED, true, null);
+		db.addMessage(txn, message, DELIVERED, true, false, null);
 
 		// The message should be visible to the contact
 		assertTrue(db.containsVisibleMessage(txn, contactId, messageId));
@@ -1961,7 +1961,7 @@ public abstract class JdbcDatabaseTest extends BrambleTestCase {
 
 		// Add a group and a message
 		db.addGroup(txn, group);
-		db.addMessage(txn, message, UNKNOWN, false, contactId);
+		db.addMessage(txn, message, UNKNOWN, false, false, contactId);
 
 		// Walk the message through the validation and delivery states
 		assertEquals(UNKNOWN, db.getMessageState(txn, messageId));
@@ -1988,7 +1988,7 @@ public abstract class JdbcDatabaseTest extends BrambleTestCase {
 		assertEquals(contactId,
 				db.addContact(txn, author, localAuthor.getId(), null, true));
 		db.addGroup(txn, group);
-		db.addMessage(txn, message, UNKNOWN, false, null);
+		db.addMessage(txn, message, UNKNOWN, false, false, null);
 
 		// There should be no messages to send
 		assertEquals(Long.MAX_VALUE, db.getNextSendTime(txn, contactId));
@@ -2073,7 +2073,7 @@ public abstract class JdbcDatabaseTest extends BrambleTestCase {
 				db.addContact(txn, author, localAuthor.getId(), null, true));
 		db.addGroup(txn, group);
 		db.addGroupVisibility(txn, contactId, groupId, true);
-		db.addMessage(txn, message, DELIVERED, true, null);
+		db.addMessage(txn, message, DELIVERED, true, false, null);
 
 		// Time: now
 		// Retrieve the message from the database
@@ -2118,7 +2118,7 @@ public abstract class JdbcDatabaseTest extends BrambleTestCase {
 				db.addContact(txn, author, localAuthor.getId(), null, true));
 		db.addGroup(txn, group);
 		db.addGroupVisibility(txn, contactId, groupId, true);
-		db.addMessage(txn, message, DELIVERED, true, null);
+		db.addMessage(txn, message, DELIVERED, true, false, null);
 
 		// Time: now
 		// Retrieve the message from the database
@@ -2257,6 +2257,58 @@ public abstract class JdbcDatabaseTest extends BrambleTestCase {
 		db.close();
 	}
 
+	@Test
+	public void testTemporaryMessages() throws Exception {
+		Message message1 = getMessage(groupId);
+		MessageId messageId1 = message1.getId();
+
+		Database<Connection> db = open(false);
+		Connection txn = db.startTransaction();
+
+		// Add a group and two temporary messages
+		db.addGroup(txn, group);
+		db.addMessage(txn, message, DELIVERED, false, true, null);
+		db.addMessage(txn, message1, DELIVERED, false, true, null);
+
+		// Mark one of the messages as permanent
+		db.setMessagePermanent(txn, messageId);
+
+		// Remove all temporary messages
+		db.removeTemporaryMessages(txn);
+
+		// The permanent message should not have been removed
+		assertTrue(db.containsMessage(txn, messageId));
+
+		// The temporary message should have been removed
+		assertFalse(db.containsMessage(txn, messageId1));
+
+		db.commitTransaction(txn);
+		db.close();
+	}
+
+	@Test
+	public void testSyncVersions() throws Exception {
+		Database<Connection> db = open(false);
+		Connection txn = db.startTransaction();
+
+		// Add a contact
+		db.addIdentity(txn, identity);
+		assertEquals(contactId,
+				db.addContact(txn, author, localAuthor.getId(), null, true));
+
+		// Only sync version 0 should be supported by default
+		List<Byte> defaultSupported = singletonList((byte) 0);
+		assertEquals(defaultSupported, db.getSyncVersions(txn, contactId));
+
+		// Set the supported versions and check that they're returned
+		List<Byte> supported = asList((byte) 0, (byte) 1);
+		db.setSyncVersions(txn, contactId, supported);
+		assertEquals(supported, db.getSyncVersions(txn, contactId));
+
+		db.commitTransaction(txn);
+		db.close();
+	}
+
 	private Database<Connection> open(boolean resume) throws Exception {
 		return open(resume, new TestMessageFactory(), new SystemClock());
 	}

bramble-core/src/test/java/org/briarproject/bramble/lifecycle/LifecycleManagerImplTest.java

@@ -42,6 +42,7 @@ public class LifecycleManagerImplTest extends BrambleMockTestCase {
 			oneOf(db).open(dbKey, lifecycleManager);
 			will(returnValue(false));
 			oneOf(db).transaction(with(false), withDbRunnable(txn));
+			oneOf(db).removeTemporaryMessages(txn);
 			allowing(eventBus).broadcast(with(any(LifecycleEvent.class)));
 		}});
 

bramble-core/src/test/java/org/briarproject/bramble/properties/TransportPropertyManagerImplTest.java

@@ -637,7 +637,8 @@ public class TransportPropertyManagerImplTest extends BrambleMockTestCase {
 			will(returnValue(timestamp));
 			oneOf(clientHelper).createMessage(g, timestamp, body);
 			will(returnValue(message));
-			oneOf(clientHelper).addLocalMessage(txn, message, meta, shared);
+			oneOf(clientHelper).addLocalMessage(txn, message, meta, shared,
+					false);
 		}});
 	}
 }

bramble-core/src/test/java/org/briarproject/bramble/rendezvous/RendezvousPollerImplTest.java

@@ -45,6 +45,7 @@ import static java.util.Collections.singletonList;
 import static java.util.concurrent.TimeUnit.MILLISECONDS;
 import static org.briarproject.bramble.api.contact.PendingContactState.ADDING_CONTACT;
 import static org.briarproject.bramble.api.contact.PendingContactState.FAILED;
+import static org.briarproject.bramble.api.contact.PendingContactState.OFFLINE;
 import static org.briarproject.bramble.api.contact.PendingContactState.WAITING_FOR_CONNECTION;
 import static org.briarproject.bramble.rendezvous.RendezvousConstants.POLLING_INTERVAL_MS;
 import static org.briarproject.bramble.rendezvous.RendezvousConstants.RENDEZVOUS_TIMEOUT_MS;
@@ -120,7 +121,7 @@ public class RendezvousPollerImplTest extends BrambleMockTestCase {
 			will(returnValue(beforeExpiry));
 			oneOf(eventBus).broadcast(with(new PredicateMatcher<>(
 					PendingContactStateChangedEvent.class, e ->
-					e.getPendingContactState() == WAITING_FOR_CONNECTION)));
+					e.getPendingContactState() == OFFLINE)));
 			// Capture the poll task
 			oneOf(scheduler).scheduleAtFixedRate(with(any(Runnable.class)),
 					with(POLLING_INTERVAL_MS), with(POLLING_INTERVAL_MS),
@@ -184,7 +185,7 @@ public class RendezvousPollerImplTest extends BrambleMockTestCase {
 		context.assertIsSatisfied();
 
 		// Add the pending contact - endpoint should be created and polled
-		expectAddUnexpiredPendingContact(beforeExpiry);
+		expectAddPendingContact(beforeExpiry, WAITING_FOR_CONNECTION);
 		expectDeriveRendezvousKey();
 		expectCreateEndpoint();
 
@@ -205,9 +206,7 @@ public class RendezvousPollerImplTest extends BrambleMockTestCase {
 		context.assertIsSatisfied();
 
 		// Remove the pending contact - endpoint should be closed
-		context.checking(new Expectations() {{
+		expectCloseEndpoint();
-			oneOf(rendezvousEndpoint).close();
-		}});
 
 		rendezvousPoller.eventOccurred(
 				new PendingContactRemovedEvent(pendingContact.getId()));
@@ -238,7 +237,7 @@ public class RendezvousPollerImplTest extends BrambleMockTestCase {
 		context.assertIsSatisfied();
 
 		// Add the pending contact - endpoint should be created and polled
-		expectAddUnexpiredPendingContact(beforeExpiry);
+		expectAddPendingContact(beforeExpiry, WAITING_FOR_CONNECTION);
 		expectDeriveRendezvousKey();
 		expectCreateEndpoint();
 
@@ -260,10 +259,7 @@ public class RendezvousPollerImplTest extends BrambleMockTestCase {
 
 		// Run the poll task - pending contact expires, endpoint is closed
 		expectPendingContactExpires(afterExpiry);
-
+		expectCloseEndpoint();
-		context.checking(new Expectations() {{
-			oneOf(rendezvousEndpoint).close();
-		}});
 
 		capturePollTask.get().run();
 		context.assertIsSatisfied();
@@ -289,7 +285,7 @@ public class RendezvousPollerImplTest extends BrambleMockTestCase {
 		context.assertIsSatisfied();
 
 		// Add the pending contact - no endpoints should be created yet
-		expectAddUnexpiredPendingContact(beforeExpiry);
+		expectAddPendingContact(beforeExpiry, OFFLINE);
 		expectDeriveRendezvousKey();
 
 		rendezvousPoller.eventOccurred(
@@ -299,14 +295,14 @@ public class RendezvousPollerImplTest extends BrambleMockTestCase {
 		// Enable the transport - endpoint should be created
 		expectGetPlugin();
 		expectCreateEndpoint();
+		expectStateChangedEvent(WAITING_FOR_CONNECTION);
 
 		rendezvousPoller.eventOccurred(new TransportEnabledEvent(transportId));
 		context.assertIsSatisfied();
 
 		// Disable the transport - endpoint should be closed
-		context.checking(new Expectations() {{
+		expectCloseEndpoint();
-			oneOf(rendezvousEndpoint).close();
+		expectStateChangedEvent(OFFLINE);
-		}});
 
 		rendezvousPoller.eventOccurred(new TransportDisabledEvent(transportId));
 		context.assertIsSatisfied();
@@ -482,13 +478,14 @@ public class RendezvousPollerImplTest extends BrambleMockTestCase {
 		return capturePollTask;
 	}
 
-	private void expectAddUnexpiredPendingContact(long now) {
+	private void expectAddPendingContact(long now,
+			PendingContactState initialState) {
 		context.checking(new Expectations() {{
 			oneOf(clock).currentTimeMillis();
 			will(returnValue(now));
 			oneOf(eventBus).broadcast(with(new PredicateMatcher<>(
 					PendingContactStateChangedEvent.class, e ->
-					e.getPendingContactState() == WAITING_FOR_CONNECTION)));
+					e.getPendingContactState() == initialState)));
 		}});
 	}
 
@@ -546,7 +543,7 @@ public class RendezvousPollerImplTest extends BrambleMockTestCase {
 			will(returnValue(now));
 			oneOf(eventBus).broadcast(with(new PredicateMatcher<>(
 					PendingContactStateChangedEvent.class, e ->
-					e.getPendingContactState() == WAITING_FOR_CONNECTION)));
+					e.getPendingContactState() == OFFLINE)));
 			// Capture the poll task
 			oneOf(scheduler).scheduleAtFixedRate(with(any(Runnable.class)),
 					with(POLLING_INTERVAL_MS), with(POLLING_INTERVAL_MS),
@@ -576,4 +573,10 @@ public class RendezvousPollerImplTest extends BrambleMockTestCase {
 					e.getPendingContactState() == state)));
 		}});
 	}
+
+	private void expectCloseEndpoint() throws Exception {
+		context.checking(new Expectations() {{
+			oneOf(rendezvousEndpoint).close();
+		}});
+	}
 }

bramble-core/src/test/java/org/briarproject/bramble/sync/SimplexOutgoingSessionTest.java

@@ -9,6 +9,7 @@ import org.briarproject.bramble.api.sync.GroupId;
 import org.briarproject.bramble.api.sync.Message;
 import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.bramble.api.sync.SyncRecordWriter;
+import org.briarproject.bramble.api.sync.Versions;
 import org.briarproject.bramble.api.transport.StreamWriter;
 import org.briarproject.bramble.test.BrambleMockTestCase;
 import org.briarproject.bramble.test.DbExpectations;
@@ -49,6 +50,8 @@ public class SimplexOutgoingSessionTest extends BrambleMockTestCase {
 		context.checking(new DbExpectations() {{
 			// Add listener
 			oneOf(eventBus).addListener(session);
+			// Send the protocol versions
+			oneOf(recordWriter).writeVersions(with(any(Versions.class)));
 			// No acks to send
 			oneOf(db).transactionWithNullableResult(with(false),
 					withNullableDbCallable(noAckTxn));
@@ -83,6 +86,8 @@ public class SimplexOutgoingSessionTest extends BrambleMockTestCase {
 		context.checking(new DbExpectations() {{
 			// Add listener
 			oneOf(eventBus).addListener(session);
+			// Send the protocol versions
+			oneOf(recordWriter).writeVersions(with(any(Versions.class)));
 			// One ack to send
 			oneOf(db).transactionWithNullableResult(with(false),
 					withNullableDbCallable(ackTxn));

bramble-core/src/test/java/org/briarproject/bramble/sync/SyncRecordReaderImplTest.java

@@ -10,11 +10,14 @@ import org.briarproject.bramble.api.sync.MessageFactory;
 import org.briarproject.bramble.api.sync.Offer;
 import org.briarproject.bramble.api.sync.Request;
 import org.briarproject.bramble.api.sync.SyncRecordReader;
+import org.briarproject.bramble.api.sync.Versions;
 import org.briarproject.bramble.test.BrambleMockTestCase;
 import org.jmock.Expectations;
+import org.junit.Before;
 import org.junit.Test;
 
 import java.io.ByteArrayOutputStream;
+import java.util.List;
 
 import javax.annotation.Nullable;
 
@@ -22,7 +25,9 @@ import static org.briarproject.bramble.api.record.Record.MAX_RECORD_PAYLOAD_BYTE
 import static org.briarproject.bramble.api.sync.RecordTypes.ACK;
 import static org.briarproject.bramble.api.sync.RecordTypes.OFFER;
 import static org.briarproject.bramble.api.sync.RecordTypes.REQUEST;
+import static org.briarproject.bramble.api.sync.RecordTypes.VERSIONS;
 import static org.briarproject.bramble.api.sync.SyncConstants.MAX_MESSAGE_IDS;
+import static org.briarproject.bramble.api.sync.SyncConstants.MAX_SUPPORTED_VERSIONS;
 import static org.briarproject.bramble.api.sync.SyncConstants.PROTOCOL_VERSION;
 import static org.briarproject.bramble.test.TestUtils.getRandomId;
 import static org.junit.Assert.assertEquals;
@@ -35,12 +40,17 @@ public class SyncRecordReaderImplTest extends BrambleMockTestCase {
 			context.mock(MessageFactory.class);
 	private final RecordReader recordReader = context.mock(RecordReader.class);
 
+	private SyncRecordReader reader;
+
+	@Before
+	public void setUp() {
+		reader = new SyncRecordReaderImpl(messageFactory, recordReader);
+	}
+
 	@Test
 	public void testNoFormatExceptionIfAckIsMaximumSize() throws Exception {
 		expectReadRecord(createAck());
 
-		SyncRecordReader reader =
-				new SyncRecordReaderImpl(messageFactory, recordReader);
 		Ack ack = reader.readAck();
 		assertEquals(MAX_MESSAGE_IDS, ack.getMessageIds().size());
 	}
@@ -49,8 +59,6 @@ public class SyncRecordReaderImplTest extends BrambleMockTestCase {
 	public void testFormatExceptionIfAckIsEmpty() throws Exception {
 		expectReadRecord(createEmptyAck());
 
-		SyncRecordReader reader =
-				new SyncRecordReaderImpl(messageFactory, recordReader);
 		reader.readAck();
 	}
 
@@ -58,8 +66,6 @@ public class SyncRecordReaderImplTest extends BrambleMockTestCase {
 	public void testNoFormatExceptionIfOfferIsMaximumSize() throws Exception {
 		expectReadRecord(createOffer());
 
-		SyncRecordReader reader =
-				new SyncRecordReaderImpl(messageFactory, recordReader);
 		Offer offer = reader.readOffer();
 		assertEquals(MAX_MESSAGE_IDS, offer.getMessageIds().size());
 	}
@@ -68,8 +74,6 @@ public class SyncRecordReaderImplTest extends BrambleMockTestCase {
 	public void testFormatExceptionIfOfferIsEmpty() throws Exception {
 		expectReadRecord(createEmptyOffer());
 
-		SyncRecordReader reader =
-				new SyncRecordReaderImpl(messageFactory, recordReader);
 		reader.readOffer();
 	}
 
@@ -77,8 +81,6 @@ public class SyncRecordReaderImplTest extends BrambleMockTestCase {
 	public void testNoFormatExceptionIfRequestIsMaximumSize() throws Exception {
 		expectReadRecord(createRequest());
 
-		SyncRecordReader reader =
-				new SyncRecordReaderImpl(messageFactory, recordReader);
 		Request request = reader.readRequest();
 		assertEquals(MAX_MESSAGE_IDS, request.getMessageIds().size());
 	}
@@ -87,11 +89,36 @@ public class SyncRecordReaderImplTest extends BrambleMockTestCase {
 	public void testFormatExceptionIfRequestIsEmpty() throws Exception {
 		expectReadRecord(createEmptyRequest());
 
-		SyncRecordReader reader =
-				new SyncRecordReaderImpl(messageFactory, recordReader);
 		reader.readRequest();
 	}
 
+	@Test
+	public void testNoFormatExceptionIfVersionsIsMaximumSize()
+			throws Exception {
+		expectReadRecord(createVersions(MAX_SUPPORTED_VERSIONS));
+
+		Versions versions = reader.readVersions();
+		List<Byte> supported = versions.getSupportedVersions();
+		assertEquals(MAX_SUPPORTED_VERSIONS, supported.size());
+		for (int i = 0; i < supported.size(); i++) {
+			assertEquals(i, (int) supported.get(i));
+		}
+	}
+
+	@Test(expected = FormatException.class)
+	public void testFormatExceptionIfVersionsIsEmpty() throws Exception {
+		expectReadRecord(createVersions(0));
+
+		reader.readVersions();
+	}
+
+	@Test(expected = FormatException.class)
+	public void testFormatExceptionIfVersionsIsTooLarge() throws Exception {
+		expectReadRecord(createVersions(MAX_SUPPORTED_VERSIONS + 1));
+
+		reader.readVersions();
+	}
+
 	@Test
 	public void testEofReturnsTrueWhenAtEndOfStream() throws Exception {
 		expectReadRecord(createAck());
@@ -140,6 +167,12 @@ public class SyncRecordReaderImplTest extends BrambleMockTestCase {
 		return new Record(PROTOCOL_VERSION, REQUEST, new byte[0]);
 	}
 
+	private Record createVersions(int numVersions) {
+		byte[] payload = new byte[numVersions];
+		for (int i = 0; i < payload.length; i++) payload[i] = (byte) i;
+		return new Record(PROTOCOL_VERSION, VERSIONS, payload);
+	}
+
 	private byte[] createPayload() throws Exception {
 		ByteArrayOutputStream payload = new ByteArrayOutputStream();
 		while (payload.size() + UniqueId.LENGTH <= MAX_RECORD_PAYLOAD_BYTES) {

bramble-core/src/test/java/org/briarproject/bramble/sync/validation/ValidationManagerImplTest.java

@@ -28,7 +28,6 @@ import java.util.Map;
 import java.util.concurrent.Executor;
 
 import static java.util.Arrays.asList;
-import static java.util.Collections.emptyList;
 import static java.util.Collections.emptyMap;
 import static java.util.Collections.singletonList;
 import static java.util.Collections.singletonMap;
@@ -80,24 +79,9 @@ public class ValidationManagerImplTest extends BrambleMockTestCase {
 
 	@Test
 	public void testStartAndStop() throws Exception {
-		Transaction txn = new Transaction(null, true);
+		expectGetMessagesToValidate();
-		Transaction txn1 = new Transaction(null, true);
+		expectGetPendingMessages();
-		Transaction txn2 = new Transaction(null, true);
+		expectGetMessagesToShare();
-
-		context.checking(new DbExpectations() {{
-			// validateOutstandingMessages()
-			oneOf(db).transactionWithResult(with(true), withDbCallable(txn));
-			oneOf(db).getMessagesToValidate(txn);
-			will(returnValue(emptyList()));
-			// deliverOutstandingMessages()
-			oneOf(db).transactionWithResult(with(true), withDbCallable(txn1));
-			oneOf(db).getPendingMessages(txn1);
-			will(returnValue(emptyList()));
-			// shareOutstandingMessages()
-			oneOf(db).transactionWithResult(with(true), withDbCallable(txn2));
-			oneOf(db).getMessagesToShare(txn2);
-			will(returnValue(emptyList()));
-		}});
 
 		vm.startService();
 		vm.stopService();
@@ -106,167 +90,134 @@ public class ValidationManagerImplTest extends BrambleMockTestCase {
 	@Test
 	public void testMessagesAreValidatedAtStartup() throws Exception {
 		Transaction txn = new Transaction(null, true);
-		Transaction txn1 = new Transaction(null, true);
+		Transaction txn1 = new Transaction(null, false);
-		Transaction txn2 = new Transaction(null, false);
+		Transaction txn2 = new Transaction(null, true);
-		Transaction txn3 = new Transaction(null, true);
+		Transaction txn3 = new Transaction(null, false);
-		Transaction txn4 = new Transaction(null, false);
+
-		Transaction txn5 = new Transaction(null, true);
+		expectGetMessagesToValidate(messageId, messageId1);
-		Transaction txn6 = new Transaction(null, true);
 
 		context.checking(new DbExpectations() {{
-			// Get messages to validate
-			oneOf(db).transactionWithResult(with(true), withDbCallable(txn));
-			oneOf(db).getMessagesToValidate(txn);
-			will(returnValue(asList(messageId, messageId1)));
 			// Load the first raw message and group
-			oneOf(db).transactionWithResult(with(true), withDbCallable(txn1));
+			oneOf(db).transactionWithResult(with(true), withDbCallable(txn));
-			oneOf(db).getMessage(txn1, messageId);
+			oneOf(db).getMessage(txn, messageId);
 			will(returnValue(message));
-			oneOf(db).getGroup(txn1, groupId);
+			oneOf(db).getGroup(txn, groupId);
 			will(returnValue(group));
 			// Validate the first message: valid
 			oneOf(validator).validateMessage(message, group);
 			will(returnValue(validResult));
 			// Store the validation result for the first message
-			oneOf(db).transaction(with(false), withDbRunnable(txn2));
+			oneOf(db).transaction(with(false), withDbRunnable(txn1));
-			oneOf(db).mergeMessageMetadata(txn2, messageId, metadata);
+			oneOf(db).mergeMessageMetadata(txn1, messageId, metadata);
 			// Deliver the first message
-			oneOf(hook).incomingMessage(txn2, message, metadata);
+			oneOf(hook).incomingMessage(txn1, message, metadata);
 			will(returnValue(false));
-			oneOf(db).setMessageState(txn2, messageId, DELIVERED);
+			oneOf(db).setMessageState(txn1, messageId, DELIVERED);
 			// Get any pending dependents
-			oneOf(db).getMessageDependents(txn2, messageId);
+			oneOf(db).getMessageDependents(txn1, messageId);
 			will(returnValue(emptyMap()));
 			// Load the second raw message and group
-			oneOf(db).transactionWithResult(with(true), withDbCallable(txn3));
+			oneOf(db).transactionWithResult(with(true), withDbCallable(txn2));
-			oneOf(db).getMessage(txn3, messageId1);
+			oneOf(db).getMessage(txn2, messageId1);
 			will(returnValue(message1));
-			oneOf(db).getGroup(txn3, groupId);
+			oneOf(db).getGroup(txn2, groupId);
 			will(returnValue(group));
 			// Validate the second message: invalid
 			oneOf(validator).validateMessage(message1, group);
 			will(throwException(new InvalidMessageException()));
 			// Store the validation result for the second message
-			oneOf(db).transaction(with(false), withDbRunnable(txn4));
+			oneOf(db).transaction(with(false), withDbRunnable(txn3));
-			oneOf(db).getMessageState(txn4, messageId1);
+			oneOf(db).getMessageState(txn3, messageId1);
 			will(returnValue(UNKNOWN));
-			oneOf(db).setMessageState(txn4, messageId1, INVALID);
+			oneOf(db).setMessageState(txn3, messageId1, INVALID);
-			oneOf(db).deleteMessage(txn4, messageId1);
+			oneOf(db).deleteMessage(txn3, messageId1);
-			oneOf(db).deleteMessageMetadata(txn4, messageId1);
+			oneOf(db).deleteMessageMetadata(txn3, messageId1);
 			// Recursively invalidate any dependents
-			oneOf(db).getMessageDependents(txn4, messageId1);
+			oneOf(db).getMessageDependents(txn3, messageId1);
 			will(returnValue(emptyMap()));
-			// Get pending messages to deliver
-			oneOf(db).transactionWithResult(with(true), withDbCallable(txn5));
-			oneOf(db).getPendingMessages(txn5);
-			will(returnValue(emptyList()));
-			// Get messages to share
-			oneOf(db).transactionWithResult(with(true), withDbCallable(txn6));
-			oneOf(db).getMessagesToShare(txn6);
-			will(returnValue(emptyList()));
 		}});
 
+		expectGetPendingMessages();
+		expectGetMessagesToShare();
+
 		vm.startService();
 	}
 
 	@Test
 	public void testPendingMessagesAreDeliveredAtStartup() throws Exception {
-		Transaction txn = new Transaction(null, true);
+		Transaction txn = new Transaction(null, false);
-		Transaction txn1 = new Transaction(null, true);
+		Transaction txn1 = new Transaction(null, false);
-		Transaction txn2 = new Transaction(null, false);
+
-		Transaction txn3 = new Transaction(null, false);
+		expectGetMessagesToValidate();
-		Transaction txn4 = new Transaction(null, true);
+		expectGetPendingMessages(messageId);
 
 		context.checking(new DbExpectations() {{
-			// Get messages to validate
-			oneOf(db).transactionWithResult(with(true), withDbCallable(txn));
-			oneOf(db).getMessagesToValidate(txn);
-			will(returnValue(emptyList()));
-			// Get pending messages to deliver
-			oneOf(db).transactionWithResult(with(true), withDbCallable(txn1));
-			oneOf(db).getPendingMessages(txn1);
-			will(returnValue(singletonList(messageId)));
 			// Check whether the message is ready to deliver
-			oneOf(db).transaction(with(false), withDbRunnable(txn2));
+			oneOf(db).transaction(with(false), withDbRunnable(txn));
-			oneOf(db).getMessageState(txn2, messageId);
+			oneOf(db).getMessageState(txn, messageId);
 			will(returnValue(PENDING));
-			oneOf(db).getMessageDependencies(txn2, messageId);
+			oneOf(db).getMessageDependencies(txn, messageId);
 			will(returnValue(singletonMap(messageId1, DELIVERED)));
 			// Get the message and its metadata to deliver
-			oneOf(db).getMessage(txn2, messageId);
+			oneOf(db).getMessage(txn, messageId);
 			will(returnValue(message));
-			oneOf(db).getGroup(txn2, groupId);
+			oneOf(db).getGroup(txn, groupId);
 			will(returnValue(group));
-			oneOf(db).getMessageMetadataForValidator(txn2, messageId);
+			oneOf(db).getMessageMetadataForValidator(txn, messageId);
 			will(returnValue(new Metadata()));
 			// Deliver the message
-			oneOf(hook).incomingMessage(txn2, message, metadata);
+			oneOf(hook).incomingMessage(txn, message, metadata);
 			will(returnValue(false));
-			oneOf(db).setMessageState(txn2, messageId, DELIVERED);
+			oneOf(db).setMessageState(txn, messageId, DELIVERED);
 			// Get any pending dependents
-			oneOf(db).getMessageDependents(txn2, messageId);
+			oneOf(db).getMessageDependents(txn, messageId);
 			will(returnValue(singletonMap(messageId2, PENDING)));
 			// Check whether the dependent is ready to deliver
-			oneOf(db).transaction(with(false), withDbRunnable(txn3));
+			oneOf(db).transaction(with(false), withDbRunnable(txn1));
-			oneOf(db).getMessageState(txn3, messageId2);
+			oneOf(db).getMessageState(txn1, messageId2);
 			will(returnValue(PENDING));
-			oneOf(db).getMessageDependencies(txn3, messageId2);
+			oneOf(db).getMessageDependencies(txn1, messageId2);
 			will(returnValue(singletonMap(messageId1, DELIVERED)));
 			// Get the dependent and its metadata to deliver
-			oneOf(db).getMessage(txn3, messageId2);
+			oneOf(db).getMessage(txn1, messageId2);
 			will(returnValue(message2));
-			oneOf(db).getGroup(txn3, groupId);
+			oneOf(db).getGroup(txn1, groupId);
 			will(returnValue(group));
-			oneOf(db).getMessageMetadataForValidator(txn3, messageId2);
+			oneOf(db).getMessageMetadataForValidator(txn1, messageId2);
 			will(returnValue(metadata));
 			// Deliver the dependent
-			oneOf(hook).incomingMessage(txn3, message2, metadata);
+			oneOf(hook).incomingMessage(txn1, message2, metadata);
 			will(returnValue(false));
-			oneOf(db).setMessageState(txn3, messageId2, DELIVERED);
+			oneOf(db).setMessageState(txn1, messageId2, DELIVERED);
 			// Get any pending dependents
-			oneOf(db).getMessageDependents(txn3, messageId2);
+			oneOf(db).getMessageDependents(txn1, messageId2);
 			will(returnValue(emptyMap()));
-
-			// Get messages to share
-			oneOf(db).transactionWithResult(with(true), withDbCallable(txn4));
-			oneOf(db).getMessagesToShare(txn4);
-			will(returnValue(emptyList()));
 		}});
 
+		expectGetMessagesToShare();
+
 		vm.startService();
 	}
 
 	@Test
 	public void testMessagesAreSharedAtStartup() throws Exception {
-		Transaction txn = new Transaction(null, true);
+		Transaction txn = new Transaction(null, false);
-		Transaction txn1 = new Transaction(null, true);
+		Transaction txn1 = new Transaction(null, false);
-		Transaction txn2 = new Transaction(null, true);
+
-		Transaction txn3 = new Transaction(null, false);
+		expectGetMessagesToValidate();
-		Transaction txn4 = new Transaction(null, false);
+		expectGetPendingMessages();
+		expectGetMessagesToShare(messageId);
 
 		context.checking(new DbExpectations() {{
-			// No messages to validate
-			oneOf(db).transactionWithResult(with(true), withDbCallable(txn));
-			oneOf(db).getMessagesToValidate(txn);
-			will(returnValue(emptyList()));
-			// No pending messages to deliver
-			oneOf(db).transactionWithResult(with(true), withDbCallable(txn1));
-			oneOf(db).getPendingMessages(txn1);
-			will(returnValue(emptyList()));
-
-			// Get messages to share
-			oneOf(db).transactionWithResult(with(true), withDbCallable(txn2));
-			oneOf(db).getMessagesToShare(txn2);
-			will(returnValue(singletonList(messageId)));
 			// Share message and get dependencies
-			oneOf(db).transaction(with(false), withDbRunnable(txn3));
+			oneOf(db).transaction(with(false), withDbRunnable(txn));
-			oneOf(db).setMessageShared(txn3, messageId);
+			oneOf(db).setMessageShared(txn, messageId);
-			oneOf(db).getMessageDependencies(txn3, messageId);
+			oneOf(db).getMessageDependencies(txn, messageId);
 			will(returnValue(singletonMap(messageId2, DELIVERED)));
 			// Share dependency
-			oneOf(db).transaction(with(false), withDbRunnable(txn4));
+			oneOf(db).transaction(with(false), withDbRunnable(txn1));
-			oneOf(db).setMessageShared(txn4, messageId2);
+			oneOf(db).setMessageShared(txn1, messageId2);
-			oneOf(db).getMessageDependencies(txn4, messageId2);
+			oneOf(db).getMessageDependencies(txn1, messageId2);
 			will(returnValue(emptyMap()));
 		}});
 
@@ -318,49 +269,39 @@ public class ValidationManagerImplTest extends BrambleMockTestCase {
 			throws Exception {
 		Transaction txn = new Transaction(null, true);
 		Transaction txn1 = new Transaction(null, true);
-		Transaction txn2 = new Transaction(null, true);
+		Transaction txn2 = new Transaction(null, false);
-		Transaction txn3 = new Transaction(null, false);
+
-		Transaction txn4 = new Transaction(null, true);
+		expectGetMessagesToValidate(messageId, messageId1);
-		Transaction txn5 = new Transaction(null, true);
 
 		context.checking(new DbExpectations() {{
-			// Get messages to validate
-			oneOf(db).transactionWithResult(with(true), withDbCallable(txn));
-			oneOf(db).getMessagesToValidate(txn);
-			will(returnValue(asList(messageId, messageId1)));
 			// Load the first raw message - *gasp* it's gone!
-			oneOf(db).transactionWithResult(with(true), withDbCallable(txn1));
+			oneOf(db).transactionWithResult(with(true), withDbCallable(txn));
-			oneOf(db).getMessage(txn1, messageId);
+			oneOf(db).getMessage(txn, messageId);
 			will(throwException(new NoSuchMessageException()));
 			// Load the second raw message and group
-			oneOf(db).transactionWithResult(with(true), withDbCallable(txn2));
+			oneOf(db).transactionWithResult(with(true), withDbCallable(txn1));
-			oneOf(db).getMessage(txn2, messageId1);
+			oneOf(db).getMessage(txn1, messageId1);
 			will(returnValue(message1));
-			oneOf(db).getGroup(txn2, groupId);
+			oneOf(db).getGroup(txn1, groupId);
 			will(returnValue(group));
 			// Validate the second message: invalid
 			oneOf(validator).validateMessage(message1, group);
 			will(throwException(new InvalidMessageException()));
 			// Invalidate the second message
-			oneOf(db).transaction(with(false), withDbRunnable(txn3));
+			oneOf(db).transaction(with(false), withDbRunnable(txn2));
-			oneOf(db).getMessageState(txn3, messageId1);
+			oneOf(db).getMessageState(txn2, messageId1);
 			will(returnValue(UNKNOWN));
-			oneOf(db).setMessageState(txn3, messageId1, INVALID);
+			oneOf(db).setMessageState(txn2, messageId1, INVALID);
-			oneOf(db).deleteMessage(txn3, messageId1);
+			oneOf(db).deleteMessage(txn2, messageId1);
-			oneOf(db).deleteMessageMetadata(txn3, messageId1);
+			oneOf(db).deleteMessageMetadata(txn2, messageId1);
 			// Recursively invalidate dependents
-			oneOf(db).getMessageDependents(txn3, messageId1);
+			oneOf(db).getMessageDependents(txn2, messageId1);
 			will(returnValue(emptyMap()));
-			// Get pending messages to deliver
-			oneOf(db).transactionWithResult(with(true), withDbCallable(txn4));
-			oneOf(db).getPendingMessages(txn4);
-			will(returnValue(emptyList()));
-			// Get messages to share
-			oneOf(db).transactionWithResult(with(true), withDbCallable(txn5));
-			oneOf(db).getMessagesToShare(txn5);
-			will(returnValue(emptyList()));
 		}});
 
+		expectGetPendingMessages();
+		expectGetMessagesToShare();
+
 		vm.startService();
 	}
 
@@ -369,52 +310,42 @@ public class ValidationManagerImplTest extends BrambleMockTestCase {
 			throws Exception {
 		Transaction txn = new Transaction(null, true);
 		Transaction txn1 = new Transaction(null, true);
-		Transaction txn2 = new Transaction(null, true);
+		Transaction txn2 = new Transaction(null, false);
-		Transaction txn3 = new Transaction(null, false);
+
-		Transaction txn4 = new Transaction(null, true);
+		expectGetMessagesToValidate(messageId, messageId1);
-		Transaction txn5 = new Transaction(null, true);
 
 		context.checking(new DbExpectations() {{
-			// Get messages to validate
-			oneOf(db).transactionWithResult(with(true), withDbCallable(txn));
-			oneOf(db).getMessagesToValidate(txn);
-			will(returnValue(asList(messageId, messageId1)));
 			// Load the first raw message
-			oneOf(db).transactionWithResult(with(true), withDbCallable(txn1));
+			oneOf(db).transactionWithResult(with(true), withDbCallable(txn));
-			oneOf(db).getMessage(txn1, messageId);
+			oneOf(db).getMessage(txn, messageId);
 			will(returnValue(message));
 			// Load the group - *gasp* it's gone!
-			oneOf(db).getGroup(txn1, groupId);
+			oneOf(db).getGroup(txn, groupId);
 			will(throwException(new NoSuchGroupException()));
 			// Load the second raw message and group
-			oneOf(db).transactionWithResult(with(true), withDbCallable(txn2));
+			oneOf(db).transactionWithResult(with(true), withDbCallable(txn1));
-			oneOf(db).getMessage(txn2, messageId1);
+			oneOf(db).getMessage(txn1, messageId1);
 			will(returnValue(message1));
-			oneOf(db).getGroup(txn2, groupId);
+			oneOf(db).getGroup(txn1, groupId);
 			will(returnValue(group));
 			// Validate the second message: invalid
 			oneOf(validator).validateMessage(message1, group);
 			will(throwException(new InvalidMessageException()));
 			// Store the validation result for the second message
-			oneOf(db).transaction(with(false), withDbRunnable(txn3));
+			oneOf(db).transaction(with(false), withDbRunnable(txn2));
-			oneOf(db).getMessageState(txn3, messageId1);
+			oneOf(db).getMessageState(txn2, messageId1);
 			will(returnValue(UNKNOWN));
-			oneOf(db).setMessageState(txn3, messageId1, INVALID);
+			oneOf(db).setMessageState(txn2, messageId1, INVALID);
-			oneOf(db).deleteMessage(txn3, messageId1);
+			oneOf(db).deleteMessage(txn2, messageId1);
-			oneOf(db).deleteMessageMetadata(txn3, messageId1);
+			oneOf(db).deleteMessageMetadata(txn2, messageId1);
 			// Recursively invalidate dependents
-			oneOf(db).getMessageDependents(txn3, messageId1);
+			oneOf(db).getMessageDependents(txn2, messageId1);
 			will(returnValue(emptyMap()));
-			// Get pending messages to deliver
-			oneOf(db).transactionWithResult(with(true), withDbCallable(txn4));
-			oneOf(db).getPendingMessages(txn4);
-			will(returnValue(emptyList()));
-			// Get messages to share
-			oneOf(db).transactionWithResult(with(true), withDbCallable(txn5));
-			oneOf(db).getMessagesToShare(txn5);
-			will(returnValue(emptyList()));
 		}});
 
+		expectGetPendingMessages();
+		expectGetMessagesToShare();
+
 		vm.startService();
 	}
 
@@ -801,4 +732,35 @@ public class ValidationManagerImplTest extends BrambleMockTestCase {
 
 		vm.eventOccurred(new MessageAddedEvent(message, contactId));
 	}
+
+	private void expectGetMessagesToValidate(MessageId... ids)
+			throws Exception {
+		Transaction txn = new Transaction(null, true);
+
+		context.checking(new DbExpectations() {{
+			oneOf(db).transactionWithResult(with(true), withDbCallable(txn));
+			oneOf(db).getMessagesToValidate(txn);
+			will(returnValue(asList(ids)));
+		}});
+	}
+
+	private void expectGetPendingMessages(MessageId... ids) throws Exception {
+		Transaction txn = new Transaction(null, true);
+
+		context.checking(new DbExpectations() {{
+			oneOf(db).transactionWithResult(with(true), withDbCallable(txn));
+			oneOf(db).getPendingMessages(txn);
+			will(returnValue(asList(ids)));
+		}});
+	}
+
+	private void expectGetMessagesToShare(MessageId... ids) throws Exception {
+		Transaction txn = new Transaction(null, true);
+
+		context.checking(new DbExpectations() {{
+			oneOf(db).transactionWithResult(with(true), withDbCallable(txn));
+			oneOf(db).getMessagesToShare(txn);
+			will(returnValue(asList(ids)));
+		}});
+	}
 }

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

@@ -1,9 +1,11 @@
 package org.briarproject.bramble.test;
 
+import org.briarproject.bramble.api.FeatureFlags;
 import org.briarproject.bramble.battery.DefaultBatteryManagerModule;
 import org.briarproject.bramble.event.DefaultEventExecutorModule;
 
 import dagger.Module;
+import dagger.Provides;
 
 @Module(includes = {
 		DefaultBatteryManagerModule.class,
@@ -13,4 +15,20 @@ import dagger.Module;
 		TestSecureRandomModule.class
 })
 public class BrambleCoreIntegrationTestModule {
+
+	@Provides
+	FeatureFlags provideFeatureFlags() {
+		return new FeatureFlags() {
+
+			@Override
+			public boolean shouldEnableImageAttachments() {
+				return true;
+			}
+
+			@Override
+			public boolean shouldEnableRemoteContacts() {
+				return true;
+			}
+		};
+	}
 }

bramble-core/src/test/java/org/briarproject/bramble/versioning/ClientVersioningManagerImplTest.java

@@ -131,7 +131,7 @@ public class ClientVersioningManagerImplTest extends BrambleMockTestCase {
 					localUpdateBody);
 			will(returnValue(localUpdate));
 			oneOf(clientHelper).addLocalMessage(txn, localUpdate,
-					localUpdateMeta, true);
+					localUpdateMeta, true, false);
 		}});
 	}
 
@@ -172,7 +172,7 @@ public class ClientVersioningManagerImplTest extends BrambleMockTestCase {
 					localVersionsBody);
 			will(returnValue(localVersions));
 			oneOf(db).addLocalMessage(txn, localVersions, new Metadata(),
-					false);
+					false, false);
 			// Inform contacts that client versions have changed
 			oneOf(db).getContacts(txn);
 			will(returnValue(singletonList(contact)));
@@ -259,7 +259,7 @@ public class ClientVersioningManagerImplTest extends BrambleMockTestCase {
 					newLocalVersionsBody);
 			will(returnValue(newLocalVersions));
 			oneOf(db).addLocalMessage(txn, newLocalVersions, new Metadata(),
-					false);
+					false, false);
 			// Inform contacts that client versions have changed
 			oneOf(db).getContacts(txn);
 			will(returnValue(singletonList(contact)));
@@ -284,7 +284,7 @@ public class ClientVersioningManagerImplTest extends BrambleMockTestCase {
 					newLocalUpdateBody);
 			will(returnValue(newLocalUpdate));
 			oneOf(clientHelper).addLocalMessage(txn, newLocalUpdate,
-					newLocalUpdateMeta, true);
+					newLocalUpdateMeta, true, false);
 			// No visibilities have changed
 		}});
 
@@ -355,7 +355,7 @@ public class ClientVersioningManagerImplTest extends BrambleMockTestCase {
 					newLocalVersionsBody);
 			will(returnValue(newLocalVersions));
 			oneOf(db).addLocalMessage(txn, newLocalVersions, new Metadata(),
-					false);
+					false, false);
 			// Inform contacts that client versions have changed
 			oneOf(db).getContacts(txn);
 			will(returnValue(singletonList(contact)));
@@ -382,7 +382,7 @@ public class ClientVersioningManagerImplTest extends BrambleMockTestCase {
 					newLocalUpdateBody);
 			will(returnValue(newLocalUpdate));
 			oneOf(clientHelper).addLocalMessage(txn, newLocalUpdate,
-					newLocalUpdateMeta, true);
+					newLocalUpdateMeta, true, false);
 			// The client's visibility has changed
 			oneOf(hook).onClientVisibilityChanging(txn, contact, visibility);
 		}});
@@ -567,7 +567,7 @@ public class ClientVersioningManagerImplTest extends BrambleMockTestCase {
 					newLocalUpdateBody);
 			will(returnValue(newLocalUpdate));
 			oneOf(clientHelper).addLocalMessage(txn, newLocalUpdate,
-					newLocalUpdateMeta, true);
+					newLocalUpdateMeta, true, false);
 			// The client's visibility has changed
 			oneOf(clientHelper).getGroupMetadataAsDictionary(txn,
 					contactGroup.getId());
@@ -640,7 +640,7 @@ public class ClientVersioningManagerImplTest extends BrambleMockTestCase {
 					newLocalUpdateBody);
 			will(returnValue(newLocalUpdate));
 			oneOf(clientHelper).addLocalMessage(txn, newLocalUpdate,
-					newLocalUpdateMeta, true);
+					newLocalUpdateMeta, true, false);
 			// The client's visibility has changed
 			oneOf(clientHelper).getGroupMetadataAsDictionary(txn,
 					contactGroup.getId());

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

@@ -1,4 +1,4 @@
-package org.briarproject.briar.android.conversation;
+package org.briarproject.briar.android.attachment;
 
 import android.content.res.AssetManager;
 import android.support.test.InstrumentationRegistry;
@@ -21,7 +21,7 @@ import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
 
 @RunWith(AndroidJUnit4.class)
-public class AttachmentControllerIntegrationTest {
+public class AttachmentRetrieverIntegrationTest {
 
 	private static final String smallKitten =
 			"https://upload.wikimedia.org/wikipedia/commons/thumb/0/06/Kitten_in_Rizal_Park%2C_Manila.jpg/160px-Kitten_in_Rizal_Park%2C_Manila.jpg";
@@ -47,15 +47,15 @@ public class AttachmentControllerIntegrationTest {
 	);
 	private final MessageId msgId = new MessageId(getRandomId());
 
-	private final AttachmentController controller =
+	private final AttachmentRetriever retriever =
-			new AttachmentController(null, dimensions);
+			new AttachmentRetriever(null, dimensions);
 
 	@Test
 	public void testSmallJpegImage() throws Exception {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/jpeg");
 		InputStream is = getUrlInputStream(smallKitten);
 		Attachment a = new Attachment(is);
-		AttachmentItem item = controller.getAttachmentItem(h, a, true);
+		AttachmentItem item = retriever.getAttachmentItem(h, a, true);
 		assertEquals(msgId, item.getMessageId());
 		assertEquals(160, item.getWidth());
 		assertEquals(240, item.getHeight());
@@ -71,7 +71,7 @@ public class AttachmentControllerIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/jpeg");
 		InputStream is = getUrlInputStream(originalKitten);
 		Attachment a = new Attachment(is);
-		AttachmentItem item = controller.getAttachmentItem(h, a, true);
+		AttachmentItem item = retriever.getAttachmentItem(h, a, true);
 		assertEquals(msgId, item.getMessageId());
 		assertEquals(1728, item.getWidth());
 		assertEquals(2592, item.getHeight());
@@ -87,7 +87,7 @@ public class AttachmentControllerIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/png");
 		InputStream is = getUrlInputStream(pngKitten);
 		Attachment a = new Attachment(is);
-		AttachmentItem item = controller.getAttachmentItem(h, a, true);
+		AttachmentItem item = retriever.getAttachmentItem(h, a, true);
 		assertEquals(msgId, item.getMessageId());
 		assertEquals(737, item.getWidth());
 		assertEquals(510, item.getHeight());
@@ -103,7 +103,7 @@ public class AttachmentControllerIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/jpeg");
 		InputStream is = getUrlInputStream(uberGif);
 		Attachment a = new Attachment(is);
-		AttachmentItem item = controller.getAttachmentItem(h, a, true);
+		AttachmentItem item = retriever.getAttachmentItem(h, a, true);
 		assertEquals(1, item.getWidth());
 		assertEquals(1, item.getHeight());
 		assertEquals(dimensions.minHeight, item.getThumbnailWidth());
@@ -118,7 +118,7 @@ public class AttachmentControllerIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/jpeg");
 		InputStream is = getUrlInputStream(lottaPixel);
 		Attachment a = new Attachment(is);
-		AttachmentItem item = controller.getAttachmentItem(h, a, true);
+		AttachmentItem item = retriever.getAttachmentItem(h, a, true);
 		assertEquals(64250, item.getWidth());
 		assertEquals(64250, item.getHeight());
 		assertEquals(dimensions.maxWidth, item.getThumbnailWidth());
@@ -133,7 +133,7 @@ public class AttachmentControllerIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/jpeg");
 		InputStream is = getUrlInputStream(imageIoCrash);
 		Attachment a = new Attachment(is);
-		AttachmentItem item = controller.getAttachmentItem(h, a, true);
+		AttachmentItem item = retriever.getAttachmentItem(h, a, true);
 		assertEquals(1184, item.getWidth());
 		assertEquals(448, item.getHeight());
 		assertEquals(dimensions.maxWidth, item.getThumbnailWidth());
@@ -148,7 +148,7 @@ public class AttachmentControllerIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/jpeg");
 		InputStream is = getUrlInputStream(gimpCrash);
 		Attachment a = new Attachment(is);
-		AttachmentItem item = controller.getAttachmentItem(h, a, true);
+		AttachmentItem item = retriever.getAttachmentItem(h, a, true);
 		assertEquals(1, item.getWidth());
 		assertEquals(1, item.getHeight());
 		assertEquals(dimensions.minHeight, item.getThumbnailWidth());
@@ -163,7 +163,7 @@ public class AttachmentControllerIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/jpeg");
 		InputStream is = getUrlInputStream(optiPngAfl);
 		Attachment a = new Attachment(is);
-		AttachmentItem item = controller.getAttachmentItem(h, a, true);
+		AttachmentItem item = retriever.getAttachmentItem(h, a, true);
 		assertEquals(32, item.getWidth());
 		assertEquals(32, item.getHeight());
 		assertEquals(dimensions.minHeight, item.getThumbnailWidth());
@@ -178,7 +178,7 @@ public class AttachmentControllerIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/jpeg");
 		InputStream is = getUrlInputStream(librawError);
 		Attachment a = new Attachment(is);
-		AttachmentItem item = controller.getAttachmentItem(h, a, true);
+		AttachmentItem item = retriever.getAttachmentItem(h, a, true);
 		assertTrue(item.hasError());
 	}
 
@@ -187,7 +187,7 @@ public class AttachmentControllerIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/gif");
 		InputStream is = getAssetInputStream("animated.gif");
 		Attachment a = new Attachment(is);
-		AttachmentItem item = controller.getAttachmentItem(h, a, true);
+		AttachmentItem item = retriever.getAttachmentItem(h, a, true);
 		assertEquals(65535, item.getWidth());
 		assertEquals(65535, item.getHeight());
 		assertEquals(dimensions.maxWidth, item.getThumbnailWidth());
@@ -202,7 +202,7 @@ public class AttachmentControllerIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/gif");
 		InputStream is = getAssetInputStream("animated2.gif");
 		Attachment a = new Attachment(is);
-		AttachmentItem item = controller.getAttachmentItem(h, a, true);
+		AttachmentItem item = retriever.getAttachmentItem(h, a, true);
 		assertEquals(10000, item.getWidth());
 		assertEquals(10000, item.getHeight());
 		assertEquals(dimensions.maxWidth, item.getThumbnailWidth());
@@ -217,7 +217,7 @@ public class AttachmentControllerIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/gif");
 		InputStream is = getAssetInputStream("error_large.gif");
 		Attachment a = new Attachment(is);
-		AttachmentItem item = controller.getAttachmentItem(h, a, true);
+		AttachmentItem item = retriever.getAttachmentItem(h, a, true);
 		assertEquals(16384, item.getWidth());
 		assertEquals(16384, item.getHeight());
 		assertEquals(dimensions.maxWidth, item.getThumbnailWidth());
@@ -232,7 +232,7 @@ public class AttachmentControllerIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/jpeg");
 		InputStream is = getAssetInputStream("error_high.jpg");
 		Attachment a = new Attachment(is);
-		AttachmentItem item = controller.getAttachmentItem(h, a, true);
+		AttachmentItem item = retriever.getAttachmentItem(h, a, true);
 		assertEquals(1, item.getWidth());
 		assertEquals(10000, item.getHeight());
 		assertEquals(dimensions.minWidth, item.getThumbnailWidth());
@@ -247,7 +247,7 @@ public class AttachmentControllerIntegrationTest {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/jpeg");
 		InputStream is = getAssetInputStream("error_wide.jpg");
 		Attachment a = new Attachment(is);
-		AttachmentItem item = controller.getAttachmentItem(h, a, true);
+		AttachmentItem item = retriever.getAttachmentItem(h, a, true);
 		assertEquals(1920, item.getWidth());
 		assertEquals(1, item.getHeight());
 		assertEquals(dimensions.maxWidth, item.getThumbnailWidth());

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

@@ -7,6 +7,7 @@ import org.briarproject.bramble.BrambleAndroidModule;
 import org.briarproject.bramble.BrambleCoreEagerSingletons;
 import org.briarproject.bramble.BrambleCoreModule;
 import org.briarproject.bramble.account.BriarAccountModule;
+import org.briarproject.bramble.api.FeatureFlags;
 import org.briarproject.bramble.api.account.AccountManager;
 import org.briarproject.bramble.api.contact.ContactExchangeManager;
 import org.briarproject.bramble.api.contact.ContactManager;
@@ -161,6 +162,8 @@ public interface AndroidComponent
 
 	ViewModelProvider.Factory viewModelFactory();
 
+	FeatureFlags featureFlags();
+
 	void inject(SignInReminderReceiver briarService);
 
 	void inject(BriarService briarService);

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

@@ -7,6 +7,7 @@ import android.os.StrictMode;
 
 import com.vanniktech.emoji.RecentEmoji;
 
+import org.briarproject.bramble.api.FeatureFlags;
 import org.briarproject.bramble.api.battery.BatteryManager;
 import org.briarproject.bramble.api.crypto.CryptoComponent;
 import org.briarproject.bramble.api.crypto.PublicKey;
@@ -59,6 +60,7 @@ import static java.util.Arrays.asList;
 import static java.util.Collections.emptyList;
 import static org.briarproject.bramble.api.reporting.ReportingConstants.DEV_ONION_ADDRESS;
 import static org.briarproject.bramble.api.reporting.ReportingConstants.DEV_PUBLIC_KEY_HEX;
+import static org.briarproject.briar.android.TestingConstants.IS_DEBUG_BUILD;
 
 @Module(includes = {ContactExchangeModule.class, ViewModelModule.class})
 public class AppModule {
@@ -230,4 +232,20 @@ public class AppModule {
 		lifecycleManager.registerOpenDatabaseHook(recentEmoji);
 		return recentEmoji;
 	}
+
+	@Provides
+	FeatureFlags provideFeatureFlags() {
+		return new FeatureFlags() {
+
+			@Override
+			public boolean shouldEnableImageAttachments() {
+				return IS_DEBUG_BUILD;
+			}
+
+			@Override
+			public boolean shouldEnableRemoteContacts() {
+				return IS_DEBUG_BUILD;
+			}
+		};
+	}
 }

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

@@ -20,6 +20,7 @@ import org.acra.annotation.ReportsCrashes;
 import org.briarproject.bramble.BrambleAndroidModule;
 import org.briarproject.bramble.BrambleCoreModule;
 import org.briarproject.briar.BriarCoreModule;
+import org.briarproject.briar.BuildConfig;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.logging.CachingLogHandler;
 import org.briarproject.briar.android.reporting.BriarReportPrimer;
@@ -64,6 +65,7 @@ import static org.briarproject.briar.android.TestingConstants.IS_DEBUG_BUILD;
 		reportDialogClass = DevReportActivity.class,
 		resDialogOkToast = R.string.dev_report_saved,
 		deleteOldUnsentReportsOnApplicationStart = false,
+		buildConfigClass = BuildConfig.class,
 		customReportContent = {
 				REPORT_ID,
 				APP_VERSION_CODE, APP_VERSION_NAME, PACKAGE_NAME,

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

@@ -30,15 +30,4 @@ public interface TestingConstants {
 	long EXPIRY_DATE = IS_DEBUG_BUILD || IS_BETA_BUILD ?
 			BuildConfig.BuildTimestamp + 90 * 24 * 60 * 60 * 1000L :
 			Long.MAX_VALUE;
-
-	/**
-	 * Feature flag for enabling image attachments.
-	 */
-	boolean FEATURE_FLAG_IMAGE_ATTACHMENTS = IS_DEBUG_BUILD;
-
-	/**
-	 * Feature flag for enabling adding contacts at a distance.
-	 */
-	boolean FEATURE_FLAG_REMOTE_CONTACTS = IS_DEBUG_BUILD;
-
 }

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

@@ -0,0 +1,187 @@
+package org.briarproject.briar.android.attachment;
+
+import android.arch.lifecycle.LiveData;
+import android.arch.lifecycle.MutableLiveData;
+import android.arch.lifecycle.Observer;
+import android.content.ContentResolver;
+import android.net.Uri;
+
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.lifecycle.IoExecutor;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.sync.GroupId;
+import org.briarproject.briar.api.messaging.Attachment;
+import org.briarproject.briar.api.messaging.AttachmentHeader;
+import org.briarproject.briar.api.messaging.MessagingManager;
+import org.jsoup.UnsupportedMimeTypeException;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.List;
+import java.util.concurrent.Executor;
+import java.util.logging.Logger;
+
+import javax.annotation.Nullable;
+import javax.annotation.concurrent.ThreadSafe;
+
+import static java.util.Objects.requireNonNull;
+import static java.util.logging.Level.INFO;
+import static java.util.logging.Level.WARNING;
+import static java.util.logging.Logger.getLogger;
+import static org.briarproject.bramble.util.IoUtils.tryToClose;
+import static org.briarproject.bramble.util.LogUtils.logDuration;
+import static org.briarproject.bramble.util.LogUtils.logException;
+import static org.briarproject.bramble.util.LogUtils.now;
+import static org.briarproject.briar.api.messaging.MessagingConstants.IMAGE_MIME_TYPES;
+
+@ThreadSafe
+@NotNullByDefault
+class AttachmentCreationTask {
+
+	private static Logger LOG =
+			getLogger(AttachmentCreationTask.class.getName());
+
+	private final Executor ioExecutor;
+	private final MessagingManager messagingManager;
+	private final ContentResolver contentResolver;
+	private final AttachmentRetriever retriever;
+	private final GroupId groupId;
+	private final Collection<Uri> uris;
+	private final boolean needsSize;
+	private final MutableLiveData<AttachmentResult> result;
+
+	private volatile boolean canceled = false;
+
+	AttachmentCreationTask(Executor ioExecutor,
+			MessagingManager messagingManager, ContentResolver contentResolver,
+			AttachmentRetriever retriever, GroupId groupId,
+			Collection<Uri> uris, boolean needsSize) {
+		this.ioExecutor = ioExecutor;
+		this.messagingManager = messagingManager;
+		this.contentResolver = contentResolver;
+		this.retriever = retriever;
+		this.groupId = groupId;
+		this.uris = uris;
+		this.needsSize = needsSize;
+		result = new MutableLiveData<>();
+	}
+
+	LiveData<AttachmentResult> getResult() {
+		return result;
+	}
+
+	/**
+	 * Cancels the task, asynchronously waits for it to finish, and deletes any
+	 * created attachments.
+	 */
+	void cancel() {
+		canceled = true;
+		// Observe the task until it finishes (which may already have happened)
+		result.observeForever(new Observer<AttachmentResult>() {
+			@Override
+			public void onChanged(@Nullable AttachmentResult attachmentResult) {
+				requireNonNull(attachmentResult);
+				if (attachmentResult.isFinished()) {
+					deleteUnsentAttachments(attachmentResult.getItemResults());
+					result.removeObserver(this);
+				}
+			}
+		});
+	}
+
+	/**
+	 * Asynchronously creates and stores the attachments.
+	 */
+	void storeAttachments() {
+		ioExecutor.execute(() -> {
+			if (LOG.isLoggable(INFO))
+				LOG.info("Storing " + uris.size() + " attachments");
+			List<AttachmentItemResult> results = new ArrayList<>();
+			for (Uri uri : uris) {
+				if (canceled) break;
+				results.add(processUri(uri));
+				result.postValue(new AttachmentResult(new ArrayList<>(results),
+						false, false));
+			}
+			result.postValue(new AttachmentResult(new ArrayList<>(results),
+					true, !canceled));
+		});
+	}
+
+	@IoExecutor
+	private AttachmentItemResult processUri(Uri uri) {
+		AttachmentHeader header = null;
+		try {
+			header = storeAttachment(uri);
+			Attachment a = retriever.getMessageAttachment(header);
+			AttachmentItem item =
+					retriever.getAttachmentItem(header, a, needsSize);
+			if (item.hasError()) throw new IOException();
+			if (needsSize) retriever.cachePut(item);
+			return new AttachmentItemResult(uri, item);
+		} catch (DbException | IOException e) {
+			logException(LOG, WARNING, e);
+			// If the attachment was already stored, delete it
+			tryToRemove(header);
+			canceled = true;
+			return new AttachmentItemResult(uri, e);
+		}
+	}
+
+	@IoExecutor
+	private AttachmentHeader storeAttachment(Uri uri)
+			throws IOException, DbException {
+		long start = now();
+		String contentType = contentResolver.getType(uri);
+		if (contentType == null) throw new IOException("null content type");
+		if (!isValidMimeType(contentType)) {
+			String uriString = uri.toString();
+			throw new UnsupportedMimeTypeException("", contentType, uriString);
+		}
+		InputStream is = contentResolver.openInputStream(uri);
+		if (is == null) throw new IOException();
+		long timestamp = System.currentTimeMillis();
+		AttachmentHeader h = messagingManager
+				.addLocalAttachment(groupId, timestamp, contentType, is);
+		tryToClose(is, LOG, WARNING);
+		logDuration(LOG, "Storing attachment", start);
+		return h;
+	}
+
+	private boolean isValidMimeType(String mimeType) {
+		for (String supportedType : IMAGE_MIME_TYPES) {
+			if (supportedType.equals(mimeType)) return true;
+		}
+		return false;
+	}
+
+	private void tryToRemove(@Nullable AttachmentHeader h) {
+		try {
+			if (h != null) messagingManager.removeAttachment(h);
+		} catch (DbException e1) {
+			logException(LOG, WARNING, e1);
+		}
+	}
+
+	private void deleteUnsentAttachments(
+			Collection<AttachmentItemResult> itemResults) {
+		List<AttachmentHeader> headers = new ArrayList<>(itemResults.size());
+		for (AttachmentItemResult itemResult : itemResults) {
+			AttachmentItem item = itemResult.getItem();
+			if (item != null) headers.add(item.getHeader());
+		}
+		if (LOG.isLoggable(INFO))
+			LOG.info("Deleting " + headers.size() + " unsent attachments");
+		ioExecutor.execute(() -> {
+			for (AttachmentHeader header : headers) {
+				try {
+					messagingManager.removeAttachment(header);
+				} catch (DbException e) {
+					logException(LOG, WARNING, e);
+				}
+			}
+		});
+	}
+}

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

@@ -0,0 +1,109 @@
+package org.briarproject.briar.android.attachment;
+
+import android.app.Application;
+import android.arch.lifecycle.LiveData;
+import android.net.Uri;
+import android.support.annotation.Nullable;
+import android.support.annotation.UiThread;
+
+import org.briarproject.bramble.api.lifecycle.IoExecutor;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.sync.GroupId;
+import org.briarproject.briar.api.messaging.AttachmentHeader;
+import org.briarproject.briar.api.messaging.MessagingManager;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.List;
+import java.util.concurrent.Executor;
+
+import static java.util.Collections.emptyList;
+
+@NotNullByDefault
+public class AttachmentCreator {
+
+	private final Application app;
+	@IoExecutor
+	private final Executor ioExecutor;
+	private final MessagingManager messagingManager;
+	private final AttachmentRetriever retriever;
+
+	@Nullable
+	private AttachmentCreationTask task;
+
+	public AttachmentCreator(Application app, @IoExecutor Executor ioExecutor,
+			MessagingManager messagingManager, AttachmentRetriever retriever) {
+		this.app = app;
+		this.ioExecutor = ioExecutor;
+		this.messagingManager = messagingManager;
+		this.retriever = retriever;
+	}
+
+	/**
+	 * Starts a background task to create attachments from the given URIs and
+	 * returns a LiveData to monitor the progress of the task.
+	 */
+	@UiThread
+	public LiveData<AttachmentResult> storeAttachments(GroupId groupId,
+			Collection<Uri> uris) {
+		if (task != null) throw new IllegalStateException();
+		boolean needsSize = uris.size() == 1;
+		task = new AttachmentCreationTask(ioExecutor, messagingManager,
+				app.getContentResolver(), retriever, groupId, uris, needsSize);
+		task.storeAttachments();
+		return task.getResult();
+	}
+
+	/**
+	 * This should be only called after configuration changes.
+	 * In this case we should not create new attachments.
+	 * They are already being created and returned by the existing LiveData.
+	 */
+	@UiThread
+	public LiveData<AttachmentResult> getLiveAttachments() {
+		if (task == null) throw new IllegalStateException();
+		// A task is already running. It will update the result LiveData.
+		// So nothing more to do here.
+		return task.getResult();
+	}
+
+	/**
+	 * Returns the headers of any attachments created by
+	 * {@link #storeAttachments(GroupId, Collection)}, unless
+	 * {@link #onAttachmentsSent()} or {@link #cancel()} has been called.
+	 */
+	@UiThread
+	public List<AttachmentHeader> getAttachmentHeadersForSending() {
+		if (task == null) return emptyList();
+		AttachmentResult result = task.getResult().getValue();
+		if (result == null) return emptyList();
+		List<AttachmentHeader> headers = new ArrayList<>();
+		for (AttachmentItemResult itemResult : result.getItemResults()) {
+			AttachmentItem item = itemResult.getItem();
+			if (item != null) headers.add(item.getHeader());
+		}
+		return headers;
+	}
+
+	/**
+	 * Informs the AttachmentCreator that the attachments created by
+	 * {@link #storeAttachments(GroupId, Collection)} will be sent.
+	 */
+	@UiThread
+	public void onAttachmentsSent() {
+		task = null; // Prevent cancel() from cancelling the task
+	}
+
+	/**
+	 * Cancels the task started by
+	 * {@link #storeAttachments(GroupId, Collection)}, if any, unless
+	 * {@link #onAttachmentsSent()} has been called.
+	 */
+	@UiThread
+	public void cancel() {
+		if (task != null) {
+			task.cancel();
+			task = null;
+		}
+	}
+}

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

@@ -1,11 +1,16 @@
-package org.briarproject.briar.android.conversation;
+package org.briarproject.briar.android.attachment;
 
 import android.content.res.Resources;
 import android.support.annotation.VisibleForTesting;
 
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.briar.R;
 
-class AttachmentDimensions {
+import javax.annotation.concurrent.Immutable;
+
+@Immutable
+@NotNullByDefault
+public class AttachmentDimensions {
 
 	final int defaultSize;
 	final int minWidth, maxWidth;
@@ -21,7 +26,7 @@ class AttachmentDimensions {
 		this.maxHeight = maxHeight;
 	}
 
-	static AttachmentDimensions getAttachmentDimensions(Resources res) {
+	public static AttachmentDimensions getAttachmentDimensions(Resources res) {
 		int defaultSize =
 				res.getDimensionPixelSize(R.dimen.message_bubble_image_default);
 		int minWidth = res.getDimensionPixelSize(
@@ -33,7 +38,7 @@ class AttachmentDimensions {
 		int maxHeight = res.getDimensionPixelSize(
 				R.dimen.message_bubble_image_max_height);
 		return new AttachmentDimensions(defaultSize, minWidth, maxWidth,
-				minHeight, minHeight);
+				minHeight, maxHeight);
 	}
 
 }

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

@@ -1,4 +1,4 @@
-package org.briarproject.briar.android.conversation;
+package org.briarproject.briar.android.attachment;
 
 import android.os.Parcel;
 import android.os.Parcelable;
@@ -6,18 +6,21 @@ import android.support.annotation.Nullable;
 
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.sync.MessageId;
+import org.briarproject.briar.api.messaging.AttachmentHeader;
 
 import java.util.concurrent.atomic.AtomicLong;
 
 import javax.annotation.concurrent.Immutable;
 
+import static java.util.Objects.requireNonNull;
+
 @Immutable
 @NotNullByDefault
 public class AttachmentItem implements Parcelable {
 
-	private final MessageId messageId;
+	private final AttachmentHeader header;
 	private final int width, height;
-	private final String mimeType, extension;
+	private final String extension;
 	private final int thumbnailWidth, thumbnailHeight;
 	private final boolean hasError;
 	private final long instanceId;
@@ -37,13 +40,12 @@ public class AttachmentItem implements Parcelable {
 
 	private static final AtomicLong NEXT_INSTANCE_ID = new AtomicLong(0);
 
-	AttachmentItem(MessageId messageId, int width, int height, String mimeType,
+	AttachmentItem(AttachmentHeader header, int width, int height,
 			String extension, int thumbnailWidth, int thumbnailHeight,
 			boolean hasError) {
-		this.messageId = messageId;
+		this.header = header;
 		this.width = width;
 		this.height = height;
-		this.mimeType = mimeType;
 		this.extension = extension;
 		this.thumbnailWidth = thumbnailWidth;
 		this.thumbnailHeight = thumbnailHeight;
@@ -54,19 +56,24 @@ public class AttachmentItem implements Parcelable {
 	protected AttachmentItem(Parcel in) {
 		byte[] messageIdByte = new byte[MessageId.LENGTH];
 		in.readByteArray(messageIdByte);
-		messageId = new MessageId(messageIdByte);
+		MessageId messageId = new MessageId(messageIdByte);
 		width = in.readInt();
 		height = in.readInt();
-		mimeType = in.readString();
+		String mimeType = requireNonNull(in.readString());
-		extension = in.readString();
+		extension = requireNonNull(in.readString());
 		thumbnailWidth = in.readInt();
 		thumbnailHeight = in.readInt();
 		hasError = in.readByte() != 0;
 		instanceId = in.readLong();
+		header = new AttachmentHeader(messageId, mimeType);
+	}
+
+	AttachmentHeader getHeader() {
+		return header;
 	}
 
 	public MessageId getMessageId() {
-		return messageId;
+		return header.getMessageId();
 	}
 
 	int getWidth() {
@@ -77,27 +84,27 @@ public class AttachmentItem implements Parcelable {
 		return height;
 	}
 
-	String getMimeType() {
+	public String getMimeType() {
-		return mimeType;
+		return header.getContentType();
 	}
 
-	String getExtension() {
+	public String getExtension() {
 		return extension;
 	}
 
-	int getThumbnailWidth() {
+	public int getThumbnailWidth() {
 		return thumbnailWidth;
 	}
 
-	int getThumbnailHeight() {
+	public int getThumbnailHeight() {
 		return thumbnailHeight;
 	}
 
-	boolean hasError() {
+	public boolean hasError() {
 		return hasError;
 	}
 
-	String getTransitionName() {
+	public String getTransitionName() {
 		return String.valueOf(instanceId);
 	}
 
@@ -108,10 +115,10 @@ public class AttachmentItem implements Parcelable {
 
 	@Override
 	public void writeToParcel(Parcel dest, int flags) {
-		dest.writeByteArray(messageId.getBytes());
+		dest.writeByteArray(header.getMessageId().getBytes());
 		dest.writeInt(width);
 		dest.writeInt(height);
-		dest.writeString(mimeType);
+		dest.writeString(header.getContentType());
 		dest.writeString(extension);
 		dest.writeInt(thumbnailWidth);
 		dest.writeInt(thumbnailHeight);

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

@@ -0,0 +1,50 @@
+package org.briarproject.briar.android.attachment;
+
+import android.net.Uri;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import javax.annotation.Nullable;
+import javax.annotation.concurrent.Immutable;
+
+@Immutable
+@NotNullByDefault
+public class AttachmentItemResult {
+
+	private final Uri uri;
+	@Nullable
+	private final AttachmentItem item;
+	@Nullable
+	private final Exception exception;
+
+	AttachmentItemResult(Uri uri, AttachmentItem item) {
+		this.uri = uri;
+		this.item = item;
+		this.exception = null;
+	}
+
+	AttachmentItemResult(Uri uri, Exception exception) {
+		this.uri = uri;
+		this.item = null;
+		this.exception = exception;
+	}
+
+	public Uri getUri() {
+		return uri;
+	}
+
+	@Nullable
+	public AttachmentItem getItem() {
+		return item;
+	}
+
+	public boolean hasError() {
+		return item == null;
+	}
+
+	@Nullable
+	public Exception getException() {
+		return exception;
+	}
+
+}

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

@@ -0,0 +1,22 @@
+package org.briarproject.briar.android.attachment;
+
+import android.arch.lifecycle.LiveData;
+import android.net.Uri;
+import android.support.annotation.UiThread;
+
+import org.briarproject.briar.api.messaging.AttachmentHeader;
+
+import java.util.Collection;
+import java.util.List;
+
+@UiThread
+public interface AttachmentManager {
+
+	LiveData<AttachmentResult> storeAttachments(Collection<Uri> uri,
+			boolean restart);
+
+	List<AttachmentHeader> getAttachmentHeadersForSending();
+
+	void cancel();
+
+}

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

@@ -0,0 +1,35 @@
+package org.briarproject.briar.android.attachment;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import java.util.Collection;
+
+import javax.annotation.concurrent.Immutable;
+
+@Immutable
+@NotNullByDefault
+public class AttachmentResult {
+
+	private final Collection<AttachmentItemResult> itemResults;
+	private final boolean finished;
+	private final boolean success;
+
+	AttachmentResult(Collection<AttachmentItemResult> itemResults,
+			boolean finished, boolean success) {
+		this.itemResults = itemResults;
+		this.finished = finished;
+		this.success = success;
+	}
+
+	public Collection<AttachmentItemResult> getItemResults() {
+		return itemResults;
+	}
+
+	public boolean isFinished() {
+		return finished;
+	}
+
+	public boolean isSuccess() {
+		return success;
+	}
+}

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

@@ -1,8 +1,9 @@
-package org.briarproject.briar.android.conversation;
+package org.briarproject.briar.android.attachment;
 
 import android.graphics.BitmapFactory;
 import android.graphics.BitmapFactory.Options;
 import android.support.annotation.Nullable;
+import android.support.annotation.VisibleForTesting;
 import android.support.media.ExifInterface;
 import android.webkit.MimeTypeMap;
 
@@ -13,7 +14,7 @@ import org.briarproject.bramble.api.db.DatabaseExecutor;
 import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.sync.MessageId;
-import org.briarproject.briar.android.conversation.ImageHelper.DecodeResult;
+import org.briarproject.briar.android.attachment.ImageHelper.DecodeResult;
 import org.briarproject.briar.api.messaging.Attachment;
 import org.briarproject.briar.api.messaging.AttachmentHeader;
 import org.briarproject.briar.api.messaging.MessagingManager;
@@ -42,10 +43,11 @@ import static org.briarproject.bramble.util.LogUtils.logException;
 import static org.briarproject.bramble.util.LogUtils.now;
 
 @NotNullByDefault
-class AttachmentController {
+public class AttachmentRetriever {
 
 	private static final Logger LOG =
-			getLogger(AttachmentController.class.getName());
+			getLogger(AttachmentRetriever.class.getName());
+
 	private static final int READ_LIMIT = 1024 * 8192;
 
 	private final MessagingManager messagingManager;
@@ -54,10 +56,11 @@ class AttachmentController {
 	private final int minWidth, maxWidth;
 	private final int minHeight, maxHeight;
 
-	private final Map<MessageId, List<AttachmentItem>> attachmentCache =
+	private final Map<MessageId, AttachmentItem> attachmentCache =
 			new ConcurrentHashMap<>();
 
-	AttachmentController(MessagingManager messagingManager,
+	@VisibleForTesting
+	AttachmentRetriever(MessagingManager messagingManager,
 			AttachmentDimensions dimensions, ImageHelper imageHelper) {
 		this.messagingManager = messagingManager;
 		this.imageHelper = imageHelper;
@@ -68,7 +71,7 @@ class AttachmentController {
 		maxHeight = dimensions.maxHeight;
 	}
 
-	AttachmentController(MessagingManager messagingManager,
+	public AttachmentRetriever(MessagingManager messagingManager,
 			AttachmentDimensions dimensions) {
 		this(messagingManager, dimensions, new ImageHelper() {
 			@Override
@@ -91,17 +94,17 @@ class AttachmentController {
 		});
 	}
 
-	void put(MessageId messageId, List<AttachmentItem> attachments) {
+	public void cachePut(AttachmentItem item) {
-		attachmentCache.put(messageId, attachments);
+		attachmentCache.put(item.getMessageId(), item);
 	}
 
 	@Nullable
-	List<AttachmentItem> get(MessageId messageId) {
+	public AttachmentItem cacheGet(MessageId attachmentId) {
-		return attachmentCache.get(messageId);
+		return attachmentCache.get(attachmentId);
 	}
 
 	@DatabaseExecutor
-	List<Pair<AttachmentHeader, Attachment>> getMessageAttachments(
+	public List<Pair<AttachmentHeader, Attachment>> getMessageAttachments(
 			List<AttachmentHeader> headers) throws DbException {
 		long start = now();
 		List<Pair<AttachmentHeader, Attachment>> attachments =
@@ -110,16 +113,20 @@ class AttachmentController {
 			Attachment a = messagingManager.getAttachment(h.getMessageId());
 			attachments.add(new Pair<>(h, a));
 		}
-		logDuration(LOG, "Loading attachment", start);
+		logDuration(LOG, "Loading attachments", start);
 		return attachments;
 	}
 
+	Attachment getMessageAttachment(AttachmentHeader h) throws DbException {
+		return messagingManager.getAttachment(h.getMessageId());
+	}
+
 	/**
 	 * Creates {@link AttachmentItem}s from the passed headers and Attachments.
 	 * <p>
 	 * Note: This closes the {@link Attachment}'s {@link InputStream}.
 	 */
-	List<AttachmentItem> getAttachmentItems(
+	public List<AttachmentItem> getAttachmentItems(
 			List<Pair<AttachmentHeader, Attachment>> attachments) {
 		boolean needsSize = attachments.size() == 1;
 		List<AttachmentItem> items = new ArrayList<>(attachments.size());
@@ -137,17 +144,15 @@ class AttachmentController {
 	 */
 	AttachmentItem getAttachmentItem(AttachmentHeader h, Attachment a,
 			boolean needsSize) {
-		MessageId messageId = h.getMessageId();
 		if (!needsSize) {
-			String mimeType = h.getContentType();
+			String extension =
-			String extension = imageHelper.getExtensionFromMimeType(mimeType);
+					imageHelper.getExtensionFromMimeType(h.getContentType());
 			boolean hasError = false;
 			if (extension == null) {
 				extension = "";
 				hasError = true;
 			}
-			return new AttachmentItem(messageId, 0, 0, mimeType, extension, 0,
+			return new AttachmentItem(h, 0, 0, extension, 0, 0, hasError);
-					0, hasError);
 		}
 
 		Size size = new Size();
@@ -185,10 +190,17 @@ class AttachmentController {
 		// get file extension
 		String extension = imageHelper.getExtensionFromMimeType(size.mimeType);
 		boolean hasError = extension == null || size.error;
+		if (!h.getContentType().equals(size.mimeType)) {
+			if (LOG.isLoggable(WARNING)) {
+				LOG.warning("Header has different mime type (" +
+						h.getContentType() + ") than image (" + size.mimeType +
+						").");
+			}
+			hasError = true;
+		}
 		if (extension == null) extension = "";
-		return new AttachmentItem(messageId, size.width, size.height,
+		return new AttachmentItem(h, size.width, size.height, extension,
-				size.mimeType, extension, thumbnailSize.width,
+				thumbnailSize.width, thumbnailSize.height, hasError);
-				thumbnailSize.height, hasError);
 	}
 
 	/**

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

@@ -1,4 +1,4 @@
-package org.briarproject.briar.android.conversation;
+package org.briarproject.briar.android.attachment;
 
 import android.support.annotation.Nullable;
 

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

@@ -1,6 +1,5 @@
 package org.briarproject.briar.android.blog;
 
-import android.net.Uri;
 import android.os.Bundle;
 import android.view.LayoutInflater;
 import android.view.View;
@@ -21,6 +20,7 @@ import org.briarproject.briar.android.fragment.BaseFragment;
 import org.briarproject.briar.android.view.TextInputView;
 import org.briarproject.briar.android.view.TextSendController;
 import org.briarproject.briar.android.view.TextSendController.SendListener;
+import org.briarproject.briar.api.messaging.AttachmentHeader;
 
 import java.util.List;
 
@@ -121,7 +121,8 @@ public class ReblogFragment extends BaseFragment implements SendListener {
 	}
 
 	@Override
-	public void onSendClick(@Nullable String text, List<Uri> imageUris) {
+	public void onSendClick(@Nullable String text,
+			List<AttachmentHeader> headers) {
 		ui.input.hideSoftKeyboard();
 		feedController.repeatPost(item, text,
 				new UiExceptionHandler<DbException>(this) {

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

@@ -1,7 +1,6 @@
 package org.briarproject.briar.android.blog;
 
 import android.content.Intent;
-import android.net.Uri;
 import android.os.Bundle;
 import android.support.annotation.Nullable;
 import android.view.KeyEvent;
@@ -27,6 +26,7 @@ import org.briarproject.briar.api.android.AndroidNotificationManager;
 import org.briarproject.briar.api.blog.BlogManager;
 import org.briarproject.briar.api.blog.BlogPost;
 import org.briarproject.briar.api.blog.BlogPostFactory;
+import org.briarproject.briar.api.messaging.AttachmentHeader;
 
 import java.security.GeneralSecurityException;
 import java.util.List;
@@ -120,7 +120,8 @@ public class WriteBlogPostActivity extends BriarActivity
 	}
 
 	@Override
-	public void onSendClick(@Nullable String text, List<Uri> imageUris) {
+	public void onSendClick(@Nullable String text,
+			List<AttachmentHeader> headers) {
 		if (isNullOrEmpty(text)) throw new AssertionError();
 
 		// hide publish button, show progress bar

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

@@ -14,6 +14,7 @@ import android.view.View;
 import android.view.ViewGroup;
 import android.widget.TextView;
 
+import org.briarproject.bramble.api.FeatureFlags;
 import org.briarproject.bramble.api.contact.Contact;
 import org.briarproject.bramble.api.contact.ContactId;
 import org.briarproject.bramble.api.contact.ContactManager;
@@ -67,7 +68,6 @@ import static java.util.logging.Level.WARNING;
 import static org.briarproject.bramble.util.LogUtils.logDuration;
 import static org.briarproject.bramble.util.LogUtils.logException;
 import static org.briarproject.bramble.util.LogUtils.now;
-import static org.briarproject.briar.android.TestingConstants.FEATURE_FLAG_REMOTE_CONTACTS;
 import static org.briarproject.briar.android.conversation.ConversationActivity.CONTACT_ID;
 import static org.briarproject.briar.android.util.UiUtils.isSamsung7;
 
@@ -85,6 +85,8 @@ public class ContactListFragment extends BaseFragment implements EventListener,
 	EventBus eventBus;
 	@Inject
 	AndroidNotificationManager notificationManager;
+	@Inject
+	FeatureFlags featureFlags;
 
 	private ContactListAdapter adapter;
 	private BriarRecyclerView list;
@@ -124,7 +126,7 @@ public class ContactListFragment extends BaseFragment implements EventListener,
 				container, false);
 
 		FabSpeedDial speedDial = contentView.findViewById(R.id.speedDial);
-		if (FEATURE_FLAG_REMOTE_CONTACTS) {
+		if (featureFlags.shouldEnableRemoteContacts()) {
 			speedDial.addOnMenuItemClickListener(this);
 		} else {
 			speedDial.setMenu(new FabSpeedDialMenu(contentView.getContext()));

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

@@ -4,6 +4,7 @@ import android.arch.lifecycle.ViewModelProvider;
 import android.arch.lifecycle.ViewModelProviders;
 import android.content.DialogInterface.OnClickListener;
 import android.os.Bundle;
+import android.support.design.widget.Snackbar;
 import android.support.v7.app.ActionBar;
 import android.support.v7.app.AlertDialog;
 import android.support.v7.widget.LinearLayoutManager;
@@ -15,6 +16,7 @@ import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.activity.ActivityComponent;
 import org.briarproject.briar.android.activity.BriarActivity;
+import org.briarproject.briar.android.util.BriarSnackbarBuilder;
 import org.briarproject.briar.android.view.BriarRecyclerView;
 
 import java.util.Collection;
@@ -22,6 +24,7 @@ import java.util.Collection;
 import javax.annotation.Nullable;
 import javax.inject.Inject;
 
+import static android.support.design.widget.Snackbar.LENGTH_INDEFINITE;
 import static org.briarproject.bramble.api.contact.PendingContactState.FAILED;
 import static org.briarproject.briar.android.contact.add.remote.PendingContactItem.POLL_DURATION_MS;
 
@@ -36,6 +39,7 @@ public class PendingContactListActivity extends BriarActivity
 	private PendingContactListViewModel viewModel;
 	private PendingContactListAdapter adapter;
 	private BriarRecyclerView list;
+	private Snackbar offlineSnackbar;
 
 	@Override
 	public void injectActivity(ActivityComponent component) {
@@ -58,6 +62,8 @@ public class PendingContactListActivity extends BriarActivity
 		viewModel.onCreate();
 		viewModel.getPendingContacts()
 				.observe(this, this::onPendingContactsChanged);
+		viewModel.getHasInternetConnection()
+				.observe(this, this::onInternetConnectionChanged);
 
 		adapter = new PendingContactListAdapter(this, this,
 				PendingContactItem.class);
@@ -66,6 +72,10 @@ public class PendingContactListActivity extends BriarActivity
 		list.setLayoutManager(new LinearLayoutManager(this));
 		list.setAdapter(adapter);
 		list.showProgressBar();
+
+		offlineSnackbar = new BriarSnackbarBuilder()
+				.setBackgroundColor(R.color.briar_red)
+				.make(list, R.string.offline_state, LENGTH_INDEFINITE);
 	}
 
 	@Override
@@ -130,4 +140,9 @@ public class PendingContactListActivity extends BriarActivity
 		}
 	}
 
+	private void onInternetConnectionChanged(boolean online) {
+		if (online) offlineSnackbar.dismiss();
+		else offlineSnackbar.show();
+	}
+
 }

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

@@ -31,6 +31,7 @@ import javax.inject.Inject;
 
 import static java.util.logging.Level.WARNING;
 import static java.util.logging.Logger.getLogger;
+import static org.briarproject.bramble.api.contact.PendingContactState.OFFLINE;
 import static org.briarproject.bramble.util.LogUtils.logException;
 
 @NotNullByDefault
@@ -48,6 +49,8 @@ public class PendingContactListViewModel extends AndroidViewModel
 
 	private final MutableLiveData<Collection<PendingContactItem>>
 			pendingContacts = new MutableLiveData<>();
+	private final MutableLiveData<Boolean> hasInternetConnection =
+			new MutableLiveData<>();
 
 	@Inject
 	PendingContactListViewModel(Application application,
@@ -88,13 +91,16 @@ public class PendingContactListViewModel extends AndroidViewModel
 				Collection<Pair<PendingContact, PendingContactState>> pairs =
 						contactManager.getPendingContacts();
 				List<PendingContactItem> items = new ArrayList<>(pairs.size());
+				boolean online = false;
 				for (Pair<PendingContact, PendingContactState> pair : pairs) {
 					PendingContact p = pair.getFirst();
+					PendingContactState state = pair.getSecond();
 					long lastPoll = rendezvousPoller.getLastPollTime(p.getId());
-					items.add(new PendingContactItem(p, pair.getSecond(),
+					items.add(new PendingContactItem(p, state, lastPoll));
-							lastPoll));
+					online = online || state != OFFLINE;
 				}
 				pendingContacts.postValue(items);
+				hasInternetConnection.postValue(online);
 			} catch (DbException e) {
 				logException(LOG, WARNING, e);
 			}
@@ -115,4 +121,8 @@ public class PendingContactListViewModel extends AndroidViewModel
 		});
 	}
 
+	LiveData<Boolean> getHasInternetConnection() {
+		return hasInternetConnection;
+	}
+
 }

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

@@ -52,6 +52,11 @@ class PendingContactViewHolder extends ViewHolder {
 						.getColor(status.getContext(), R.color.briar_yellow);
 				status.setText(R.string.waiting_for_contact_to_come_online);
 				break;
+			case OFFLINE:
+				color = ContextCompat
+						.getColor(status.getContext(), R.color.briar_yellow);
+				status.setText("");
+				break;
 			case CONNECTING:
 				status.setText(R.string.connecting);
 				break;

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

@@ -6,7 +6,6 @@ import android.arch.lifecycle.ViewModelProvider;
 import android.arch.lifecycle.ViewModelProviders;
 import android.content.DialogInterface;
 import android.content.Intent;
-import android.net.Uri;
 import android.os.Bundle;
 import android.os.Parcelable;
 import android.support.annotation.Nullable;
@@ -30,11 +29,11 @@ import android.widget.ImageView;
 import android.widget.TextView;
 import android.widget.Toast;
 
+import org.briarproject.bramble.api.FeatureFlags;
 import org.briarproject.bramble.api.Pair;
 import org.briarproject.bramble.api.contact.ContactId;
 import org.briarproject.bramble.api.contact.ContactManager;
 import org.briarproject.bramble.api.contact.event.ContactRemovedEvent;
-import org.briarproject.bramble.api.crypto.CryptoExecutor;
 import org.briarproject.bramble.api.db.DatabaseExecutor;
 import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.db.NoSuchContactException;
@@ -46,13 +45,14 @@ import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.bramble.api.plugin.ConnectionRegistry;
 import org.briarproject.bramble.api.plugin.event.ContactConnectedEvent;
 import org.briarproject.bramble.api.plugin.event.ContactDisconnectedEvent;
-import org.briarproject.bramble.api.settings.SettingsManager;
 import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.bramble.api.sync.event.MessagesAckedEvent;
 import org.briarproject.bramble.api.sync.event.MessagesSentEvent;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.activity.ActivityComponent;
 import org.briarproject.briar.android.activity.BriarActivity;
+import org.briarproject.briar.android.attachment.AttachmentItem;
+import org.briarproject.briar.android.attachment.AttachmentRetriever;
 import org.briarproject.briar.android.blog.BlogActivity;
 import org.briarproject.briar.android.conversation.ConversationVisitor.AttachmentCache;
 import org.briarproject.briar.android.conversation.ConversationVisitor.TextCache;
@@ -63,10 +63,9 @@ import org.briarproject.briar.android.util.BriarSnackbarBuilder;
 import org.briarproject.briar.android.view.BriarRecyclerView;
 import org.briarproject.briar.android.view.ImagePreview;
 import org.briarproject.briar.android.view.TextAttachmentController;
-import org.briarproject.briar.android.view.TextAttachmentController.AttachImageListener;
+import org.briarproject.briar.android.view.TextAttachmentController.AttachmentListener;
 import org.briarproject.briar.android.view.TextInputView;
 import org.briarproject.briar.android.view.TextSendController;
-import org.briarproject.briar.android.view.TextSendController.SendListener;
 import org.briarproject.briar.api.android.AndroidNotificationManager;
 import org.briarproject.briar.api.blog.BlogSharingManager;
 import org.briarproject.briar.api.client.ProtocolStateException;
@@ -81,7 +80,6 @@ import org.briarproject.briar.api.introduction.IntroductionManager;
 import org.briarproject.briar.api.messaging.Attachment;
 import org.briarproject.briar.api.messaging.AttachmentHeader;
 import org.briarproject.briar.api.messaging.MessagingManager;
-import org.briarproject.briar.api.messaging.PrivateMessageFactory;
 import org.briarproject.briar.api.messaging.PrivateMessageHeader;
 import org.briarproject.briar.api.privategroup.invitation.GroupInvitationManager;
 
@@ -92,7 +90,6 @@ import java.util.List;
 import java.util.Map;
 import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
-import java.util.concurrent.Executor;
 import java.util.logging.Logger;
 
 import javax.inject.Inject;
@@ -118,7 +115,6 @@ import static org.briarproject.bramble.util.LogUtils.logDuration;
 import static org.briarproject.bramble.util.LogUtils.logException;
 import static org.briarproject.bramble.util.LogUtils.now;
 import static org.briarproject.bramble.util.StringUtils.isNullOrEmpty;
-import static org.briarproject.briar.android.TestingConstants.FEATURE_FLAG_IMAGE_ATTACHMENTS;
 import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_ATTACH_IMAGE;
 import static org.briarproject.briar.android.activity.RequestCodes.REQUEST_INTRODUCTION;
 import static org.briarproject.briar.android.conversation.ImageActivity.ATTACHMENTS;
@@ -128,6 +124,7 @@ import static org.briarproject.briar.android.conversation.ImageActivity.NAME;
 import static org.briarproject.briar.android.util.UiUtils.getAvatarTransitionName;
 import static org.briarproject.briar.android.util.UiUtils.getBulbTransitionName;
 import static org.briarproject.briar.android.util.UiUtils.observeOnce;
+import static org.briarproject.briar.api.messaging.MessagingConstants.MAX_ATTACHMENTS_PER_MESSAGE;
 import static org.briarproject.briar.api.messaging.MessagingConstants.MAX_PRIVATE_MESSAGE_TEXT_LENGTH;
 import static uk.co.samuelwall.materialtaptargetprompt.MaterialTapTargetPrompt.STATE_DISMISSED;
 import static uk.co.samuelwall.materialtaptargetprompt.MaterialTapTargetPrompt.STATE_FINISHED;
@@ -135,8 +132,8 @@ import static uk.co.samuelwall.materialtaptargetprompt.MaterialTapTargetPrompt.S
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
 public class ConversationActivity extends BriarActivity
-		implements EventListener, ConversationListener, SendListener,
+		implements EventListener, ConversationListener, TextCache,
-		TextCache, AttachmentCache, AttachImageListener {
+		AttachmentCache, AttachmentListener {
 
 	public static final String CONTACT_ID = "briar.CONTACT_ID";
 
@@ -151,10 +148,9 @@ public class ConversationActivity extends BriarActivity
 	@Inject
 	ConnectionRegistry connectionRegistry;
 	@Inject
-	@CryptoExecutor
-	Executor cryptoExecutor;
-	@Inject
 	ViewModelProvider.Factory viewModelFactory;
+	@Inject
+	FeatureFlags featureFlags;
 
 	// Fields that are accessed from background threads must be volatile
 	@Inject
@@ -166,10 +162,6 @@ public class ConversationActivity extends BriarActivity
 	@Inject
 	volatile EventBus eventBus;
 	@Inject
-	volatile SettingsManager settingsManager;
-	@Inject
-	volatile PrivateMessageFactory privateMessageFactory;
-	@Inject
 	volatile IntroductionManager introductionManager;
 	@Inject
 	volatile ForumSharingManager forumSharingManager;
@@ -184,7 +176,7 @@ public class ConversationActivity extends BriarActivity
 		loadMessages();
 	};
 
-	private AttachmentController attachmentController;
+	private AttachmentRetriever attachmentRetriever;
 	private ConversationViewModel viewModel;
 	private ConversationVisitor visitor;
 	private ConversationAdapter adapter;
@@ -219,7 +211,7 @@ public class ConversationActivity extends BriarActivity
 
 		viewModel = ViewModelProviders.of(this, viewModelFactory)
 				.get(ConversationViewModel.class);
-		attachmentController = viewModel.getAttachmentController();
+		attachmentRetriever = viewModel.getAttachmentRetriever();
 
 		setContentView(R.layout.activity_conversation);
 
@@ -242,7 +234,7 @@ public class ConversationActivity extends BriarActivity
 			requireNonNull(deleted);
 			if (deleted) finish();
 		});
-		viewModel.getAddedPrivateMessage().observe(this,
+		viewModel.getAddedPrivateMessage().observeEvent(this,
 				this::onAddedPrivateMessage);
 
 		setTransitionName(toolbarAvatar, getAvatarTransitionName(contactId));
@@ -261,13 +253,13 @@ public class ConversationActivity extends BriarActivity
 		list.getRecyclerView().addOnScrollListener(scrollListener);
 
 		textInputView = findViewById(R.id.text_input_container);
-		if (FEATURE_FLAG_IMAGE_ATTACHMENTS) {
+		if (featureFlags.shouldEnableImageAttachments()) {
 			ImagePreview imagePreview = findViewById(R.id.imagePreview);
 			sendController = new TextAttachmentController(textInputView,
-					imagePreview, this, this);
+					imagePreview, this, viewModel);
 			observeOnce(viewModel.hasImageSupport(), this, hasSupport -> {
 				if (hasSupport != null && hasSupport) {
-					// remove cast when removing FEATURE_FLAG_IMAGE_ATTACHMENTS
+					// TODO: remove cast when removing feature flag
 					((TextAttachmentController) sendController)
 							.setImagesSupported();
 				}
@@ -302,7 +294,7 @@ public class ConversationActivity extends BriarActivity
 							Snackbar.LENGTH_SHORT)
 					.show();
 		} else if (request == REQUEST_ATTACH_IMAGE && result == RESULT_OK) {
-			// remove cast when removing FEATURE_FLAG_IMAGE_ATTACHMENTS
+			// TODO: remove cast when removing feature flag
 			((TextAttachmentController) sendController).onImageReceived(data);
 		}
 	}
@@ -451,19 +443,21 @@ public class ConversationActivity extends BriarActivity
 			if (text == null) {
 				LOG.info("Eagerly loading text for latest message");
 				text = messagingManager.getMessageText(id);
-				textCache.put(id, text);
+				textCache.put(id, requireNonNull(text));
 			}
 		}
 		// If the message has a single image, load its size - for multiple
 		// images we use a grid so the size is fixed
-		if (h.getAttachmentHeaders().size() == 1) {
+		List<AttachmentHeader> headers = h.getAttachmentHeaders();
-			List<AttachmentItem> items = attachmentController.get(id);
+		if (headers.size() == 1) {
-			if (items == null) {
+			MessageId attachmentId = headers.get(0).getMessageId();
+			AttachmentItem item = attachmentRetriever.cacheGet(attachmentId);
+			if (item == null) {
 				LOG.info("Eagerly loading image size for latest message");
-				items = attachmentController.getAttachmentItems(
+				item = attachmentRetriever.getAttachmentItems(
-						attachmentController.getMessageAttachments(
+						attachmentRetriever.getMessageAttachments(headers))
-								h.getAttachmentHeaders()));
+						.get(0);
-				attachmentController.put(id, items);
+				attachmentRetriever.cachePut(item);
 			}
 		}
 	}
@@ -475,8 +469,10 @@ public class ConversationActivity extends BriarActivity
 				adapter.incrementRevision();
 				textInputView.setReady(true);
 				// start observing onboarding after enabling
-				viewModel.showImageOnboarding().observeEvent(this,
+				if (featureFlags.shouldEnableImageAttachments()) {
-						this::showImageOnboarding);
+					viewModel.showImageOnboarding().observeEvent(this,
+							this::showImageOnboarding);
+				}
 				List<ConversationItem> items = createItems(headers);
 				adapter.addAll(items);
 				list.showData();
@@ -512,7 +508,7 @@ public class ConversationActivity extends BriarActivity
 				long start = now();
 				String text = messagingManager.getMessageText(m);
 				logDuration(LOG, "Loading text", start);
-				displayMessageText(m, text);
+				displayMessageText(m, requireNonNull(text));
 			} catch (DbException e) {
 				logException(LOG, WARNING, e);
 			}
@@ -545,10 +541,12 @@ public class ConversationActivity extends BriarActivity
 		runOnDbThread(() -> {
 			try {
 				List<Pair<AttachmentHeader, Attachment>> attachments =
-						attachmentController.getMessageAttachments(headers);
+						attachmentRetriever.getMessageAttachments(headers);
 				// TODO move getting the items off to IoExecutor, if size == 1
 				List<AttachmentItem> items =
-						attachmentController.getAttachmentItems(attachments);
+						attachmentRetriever.getAttachmentItems(attachments);
+				if (items.size() == 1)
+					attachmentRetriever.cachePut(items.get(0));
 				displayMessageAttachments(messageId, items);
 			} catch (DbException e) {
 				logException(LOG, WARNING, e);
@@ -559,7 +557,6 @@ public class ConversationActivity extends BriarActivity
 	private void displayMessageAttachments(MessageId m,
 			List<AttachmentItem> items) {
 		runOnUiThreadUnlessDestroyed(() -> {
-			attachmentController.put(m, items);
 			Pair<Integer, ConversationMessageItem> pair =
 					adapter.getMessageItem(m);
 			if (pair != null) {
@@ -658,12 +655,21 @@ public class ConversationActivity extends BriarActivity
 	}
 
 	@Override
-	public void onSendClick(@Nullable String text, List<Uri> imageUris) {
+	public void onTooManyAttachments() {
-		if (isNullOrEmpty(text) && imageUris.isEmpty())
+		String format = getResources().getString(
+				R.string.messaging_too_many_attachments_toast);
+		String warning = String.format(format, MAX_ATTACHMENTS_PER_MESSAGE);
+		Toast.makeText(this, warning, LENGTH_SHORT).show();
+	}
+
+	@Override
+	public void onSendClick(@Nullable String text,
+			List<AttachmentHeader> attachmentHeaders) {
+		if (isNullOrEmpty(text) && attachmentHeaders.isEmpty())
 			throw new AssertionError();
 		long timestamp = System.currentTimeMillis();
 		timestamp = Math.max(timestamp, getMinTimestampForNewMessage());
-		viewModel.sendMessage(text, imageUris, timestamp);
+		viewModel.sendMessage(text, attachmentHeaders, timestamp);
 		textInputView.clearText();
 	}
 
@@ -676,7 +682,6 @@ public class ConversationActivity extends BriarActivity
 	private void onAddedPrivateMessage(@Nullable PrivateMessageHeader h) {
 		if (h == null) return;
 		addConversationItem(h.accept(visitor));
-		viewModel.onAddedPrivateMessageSeen();
 	}
 
 	private void askToRemoveContact() {
@@ -726,7 +731,7 @@ public class ConversationActivity extends BriarActivity
 	}
 
 	private void showImageOnboarding() {
-		// remove cast when removing FEATURE_FLAG_IMAGE_ATTACHMENTS
+		// TODO: remove cast when removing feature flag
 		((TextAttachmentController) sendController)
 				.showImageOnboarding(this, () ->
 						viewModel.onImageOnboardingSeen());
@@ -903,12 +908,17 @@ public class ConversationActivity extends BriarActivity
 	@Override
 	public List<AttachmentItem> getAttachmentItems(MessageId m,
 			List<AttachmentHeader> headers) {
-		List<AttachmentItem> attachments = attachmentController.get(m);
+		List<AttachmentItem> items = new ArrayList<>(headers.size());
-		if (attachments == null) {
+		for (AttachmentHeader header : headers) {
-			loadMessageAttachments(m, headers);
+			AttachmentItem item =
-			return emptyList();
+					attachmentRetriever.cacheGet(header.getMessageId());
+			if (item == null) {
+				loadMessageAttachments(m, headers);
+				return emptyList();
+			}
+			items.add(item);
 		}
-		return attachments;
+		return items;
 	}
 
 }

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

@@ -4,6 +4,7 @@ import android.support.annotation.UiThread;
 import android.view.View;
 
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.briar.android.attachment.AttachmentItem;
 
 @UiThread
 @NotNullByDefault

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

@@ -3,6 +3,7 @@ package org.briarproject.briar.android.conversation;
 import android.support.annotation.LayoutRes;
 
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.briar.android.attachment.AttachmentItem;
 import org.briarproject.briar.api.messaging.PrivateMessageHeader;
 
 import java.util.List;

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

@@ -9,6 +9,7 @@ import android.view.ViewGroup;
 
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.briar.R;
+import org.briarproject.briar.android.attachment.AttachmentItem;
 
 import static android.support.constraint.ConstraintSet.WRAP_CONTENT;
 import static android.support.v4.content.ContextCompat.getColor;

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

@@ -4,42 +4,41 @@ import android.app.Application;
 import android.arch.lifecycle.AndroidViewModel;
 import android.arch.lifecycle.LiveData;
 import android.arch.lifecycle.MutableLiveData;
+import android.arch.lifecycle.Observer;
 import android.arch.lifecycle.Transformations;
-import android.content.ContentResolver;
 import android.net.Uri;
 import android.support.annotation.Nullable;
 import android.support.annotation.UiThread;
 
 import org.briarproject.bramble.api.FormatException;
-import org.briarproject.bramble.api.Pair;
 import org.briarproject.bramble.api.contact.Contact;
 import org.briarproject.bramble.api.contact.ContactId;
 import org.briarproject.bramble.api.contact.ContactManager;
-import org.briarproject.bramble.api.crypto.CryptoExecutor;
 import org.briarproject.bramble.api.db.DatabaseExecutor;
 import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.db.NoSuchContactException;
 import org.briarproject.bramble.api.db.TransactionManager;
 import org.briarproject.bramble.api.identity.AuthorId;
+import org.briarproject.bramble.api.lifecycle.IoExecutor;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.settings.Settings;
 import org.briarproject.bramble.api.settings.SettingsManager;
 import org.briarproject.bramble.api.sync.GroupId;
 import org.briarproject.bramble.api.sync.Message;
 import org.briarproject.bramble.api.sync.MessageId;
+import org.briarproject.briar.android.attachment.AttachmentCreator;
+import org.briarproject.briar.android.attachment.AttachmentManager;
+import org.briarproject.briar.android.attachment.AttachmentResult;
+import org.briarproject.briar.android.attachment.AttachmentRetriever;
 import org.briarproject.briar.android.util.UiUtils;
 import org.briarproject.briar.android.viewmodel.LiveEvent;
 import org.briarproject.briar.android.viewmodel.MutableLiveEvent;
-import org.briarproject.briar.api.messaging.Attachment;
 import org.briarproject.briar.api.messaging.AttachmentHeader;
 import org.briarproject.briar.api.messaging.MessagingManager;
 import org.briarproject.briar.api.messaging.PrivateMessage;
 import org.briarproject.briar.api.messaging.PrivateMessageFactory;
 import org.briarproject.briar.api.messaging.PrivateMessageHeader;
 
-import java.io.IOException;
-import java.io.InputStream;
-import java.util.ArrayList;
 import java.util.Collection;
 import java.util.List;
 import java.util.concurrent.Executor;
@@ -50,19 +49,20 @@ import javax.inject.Inject;
 import static java.util.Objects.requireNonNull;
 import static java.util.logging.Level.WARNING;
 import static java.util.logging.Logger.getLogger;
-import static org.briarproject.bramble.util.IoUtils.tryToClose;
 import static org.briarproject.bramble.util.LogUtils.logDuration;
 import static org.briarproject.bramble.util.LogUtils.logException;
 import static org.briarproject.bramble.util.LogUtils.now;
-import static org.briarproject.briar.android.conversation.AttachmentDimensions.getAttachmentDimensions;
+import static org.briarproject.briar.android.attachment.AttachmentDimensions.getAttachmentDimensions;
 import static org.briarproject.briar.android.settings.SettingsFragment.SETTINGS_NAMESPACE;
 import static org.briarproject.briar.android.util.UiUtils.observeForeverOnce;
 
 @NotNullByDefault
-public class ConversationViewModel extends AndroidViewModel {
+public class ConversationViewModel extends AndroidViewModel
+		implements AttachmentManager {
 
 	private static Logger LOG =
 			getLogger(ConversationViewModel.class.getName());
+
 	private static final String SHOW_ONBOARDING_IMAGE =
 			"showOnboardingImage";
 	private static final String SHOW_ONBOARDING_INTRODUCTION =
@@ -70,14 +70,13 @@ public class ConversationViewModel extends AndroidViewModel {
 
 	@DatabaseExecutor
 	private final Executor dbExecutor;
-	@CryptoExecutor
-	private final Executor cryptoExecutor;
 	private final TransactionManager db;
 	private final MessagingManager messagingManager;
 	private final ContactManager contactManager;
 	private final SettingsManager settingsManager;
 	private final PrivateMessageFactory privateMessageFactory;
-	private final AttachmentController attachmentController;
+	private final AttachmentRetriever attachmentRetriever;
+	private final AttachmentCreator attachmentCreator;
 
 	@Nullable
 	private ContactId contactId = null;
@@ -86,6 +85,7 @@ public class ConversationViewModel extends AndroidViewModel {
 			Transformations.map(contact, c -> c.getAuthor().getId());
 	private final LiveData<String> contactName =
 			Transformations.map(contact, UiUtils::getContactDisplayName);
+	private final LiveData<GroupId> messagingGroupId;
 	private final MutableLiveData<Boolean> imageSupport =
 			new MutableLiveData<>();
 	private final MutableLiveEvent<Boolean> showImageOnboarding =
@@ -96,31 +96,38 @@ public class ConversationViewModel extends AndroidViewModel {
 			new MutableLiveData<>();
 	private final MutableLiveData<Boolean> contactDeleted =
 			new MutableLiveData<>();
-	private final MutableLiveData<GroupId> messagingGroupId =
+	private final MutableLiveEvent<PrivateMessageHeader> addedHeader =
-			new MutableLiveData<>();
+			new MutableLiveEvent<>();
-	private final MutableLiveData<PrivateMessageHeader> addedHeader =
-			new MutableLiveData<>();
 
 	@Inject
 	ConversationViewModel(Application application,
 			@DatabaseExecutor Executor dbExecutor,
-			@CryptoExecutor Executor cryptoExecutor, TransactionManager db,
+			@IoExecutor Executor ioExecutor, TransactionManager db,
 			MessagingManager messagingManager, ContactManager contactManager,
 			SettingsManager settingsManager,
 			PrivateMessageFactory privateMessageFactory) {
 		super(application);
 		this.dbExecutor = dbExecutor;
-		this.cryptoExecutor = cryptoExecutor;
 		this.db = db;
 		this.messagingManager = messagingManager;
 		this.contactManager = contactManager;
 		this.settingsManager = settingsManager;
 		this.privateMessageFactory = privateMessageFactory;
-		this.attachmentController = new AttachmentController(messagingManager,
+		this.attachmentRetriever = new AttachmentRetriever(messagingManager,
 				getAttachmentDimensions(application.getResources()));
+		this.attachmentCreator = new AttachmentCreator(getApplication(),
+				ioExecutor, messagingManager, attachmentRetriever);
+		messagingGroupId = Transformations
+				.map(contact, c -> messagingManager.getContactGroup(c).getId());
 		contactDeleted.setValue(false);
 	}
 
+	@Override
+	protected void onCleared() {
+		super.onCleared();
+		attachmentCreator.cancel();
+	}
+
 	/**
 	 * Setting the {@link ContactId} automatically triggers loading of other
 	 * data.
@@ -176,25 +183,53 @@ public class ConversationViewModel extends AndroidViewModel {
 		});
 	}
 
-	void sendMessage(@Nullable String text, List<Uri> uris, long timestamp) {
+	@UiThread
-		if (messagingGroupId.getValue() == null) loadGroupId();
+	void sendMessage(@Nullable String text,
+			List<AttachmentHeader> headers, long timestamp) {
+		// messagingGroupId is loaded with the contact
 		observeForeverOnce(messagingGroupId, groupId -> {
-			if (groupId == null) return;
+			requireNonNull(groupId);
-			// calls through to creating and storing the message
+			observeForeverOnce(imageSupport, hasImageSupport -> {
-			storeAttachments(groupId, text, uris, timestamp);
+				requireNonNull(hasImageSupport);
+				createMessage(groupId, text, headers, timestamp,
+						hasImageSupport);
+			});
 		});
 	}
 
-	private void loadGroupId() {
+	@Override
-		if (contactId == null) throw new IllegalStateException();
+	@UiThread
-		dbExecutor.execute(() -> {
+	public LiveData<AttachmentResult> storeAttachments(Collection<Uri> uris,
-			try {
+			boolean restart) {
-				messagingGroupId.postValue(
+		MutableLiveData<AttachmentResult> delegate = new MutableLiveData<>();
-						messagingManager.getConversationId(contactId));
+		// messagingGroupId is loaded with the contact
-			} catch (DbException e) {
+		observeForeverOnce(messagingGroupId, groupId -> {
-				logException(LOG, WARNING, e);
+			requireNonNull(groupId);
-			}
+			LiveData<AttachmentResult> result;
+			if (restart) result = attachmentCreator.getLiveAttachments();
+			else result = attachmentCreator.storeAttachments(groupId, uris);
+			result.observeForever(new Observer<AttachmentResult>() {
+				@Override
+				public void onChanged(@Nullable AttachmentResult value) {
+					requireNonNull(value);
+					if (value.isFinished()) result.removeObserver(this);
+					delegate.setValue(value);
+				}
+			});
 		});
+		return delegate;
+	}
+
+	@Override
+	@UiThread
+	public List<AttachmentHeader> getAttachmentHeadersForSending() {
+		return attachmentCreator.getAttachmentHeadersForSending();
+	}
+
+	@Override
+	@UiThread
+	public void cancel() {
+		attachmentCreator.cancel();
 	}
 
 	@DatabaseExecutor
@@ -252,75 +287,26 @@ public class ConversationViewModel extends AndroidViewModel {
 		});
 	}
 
-	private void storeAttachments(GroupId groupId, @Nullable String text,
+	private void createMessage(GroupId groupId, @Nullable String text,
-			List<Uri> uris, long timestamp) {
+			List<AttachmentHeader> headers, long timestamp,
-		dbExecutor.execute(() -> {
+			boolean hasImageSupport) {
-			long start = now();
-			List<AttachmentHeader> attachments = new ArrayList<>();
-			List<AttachmentItem> items = new ArrayList<>();
-			boolean needsSize = uris.size() == 1;
-			for (Uri uri : uris) {
-				Pair<AttachmentHeader, AttachmentItem> pair =
-						createAttachmentHeader(groupId, uri, timestamp,
-								needsSize);
-				if (pair == null) continue;
-				attachments.add(pair.getFirst());
-				items.add(pair.getSecond());
-			}
-			logDuration(LOG, "Storing attachments", start);
-			createMessage(groupId, text, attachments, items, timestamp);
-		});
-	}
-
-	@Nullable
-	@DatabaseExecutor
-	private Pair<AttachmentHeader, AttachmentItem> createAttachmentHeader(
-			GroupId groupId, Uri uri, long timestamp, boolean needsSize) {
-		InputStream is = null;
 		try {
-			ContentResolver contentResolver =
+			PrivateMessage pm;
-					getApplication().getContentResolver();
+			if (hasImageSupport) {
-			is = contentResolver.openInputStream(uri);
+				pm = privateMessageFactory.createPrivateMessage(groupId,
-			if (is == null) throw new IOException();
+						timestamp, text, headers);
-			String contentType = contentResolver.getType(uri);
+			} else {
-			if (contentType == null) throw new IOException("null content type");
+				pm = privateMessageFactory.createLegacyPrivateMessage(
-			AttachmentHeader h = messagingManager
+						groupId, timestamp, requireNonNull(text));
-					.addLocalAttachment(groupId, timestamp, contentType, is);
+			}
-			is.close();
+			storeMessage(pm);
-			// re-open stream to get AttachmentItem
+		} catch (FormatException e) {
-			is = contentResolver.openInputStream(uri);
+			throw new AssertionError(e);
-			if (is == null) throw new IOException();
-			AttachmentItem item = attachmentController
-					.getAttachmentItem(h, new Attachment(is), needsSize);
-			return new Pair<>(h, item);
-		} catch (DbException | IOException e) {
-			logException(LOG, WARNING, e);
-			return null;
-		} finally {
-			if (is != null) tryToClose(is, LOG, WARNING);
 		}
 	}
 
-	private void createMessage(GroupId groupId, @Nullable String text,
+	private void storeMessage(PrivateMessage m) {
-			List<AttachmentHeader> attachments, List<AttachmentItem> aItems,
+		attachmentCreator.onAttachmentsSent();
-			long timestamp) {
-		cryptoExecutor.execute(() -> {
-			try {
-				// TODO remove when text can be null in the backend
-				String msgText = text == null ? "null" : text;
-				PrivateMessage pm = privateMessageFactory
-						.createPrivateMessage(groupId, timestamp, msgText,
-								attachments);
-				attachmentController.put(pm.getMessage().getId(), aItems);
-				storeMessage(pm, msgText, attachments);
-			} catch (FormatException e) {
-				throw new RuntimeException(e);
-			}
-		});
-	}
-
-	private void storeMessage(PrivateMessage m, @Nullable String text,
-			List<AttachmentHeader> attachments) {
 		dbExecutor.execute(() -> {
 			try {
 				long start = now();
@@ -330,22 +316,17 @@ public class ConversationViewModel extends AndroidViewModel {
 				PrivateMessageHeader h = new PrivateMessageHeader(
 						message.getId(), message.getGroupId(),
 						message.getTimestamp(), true, true, false, false,
-						text != null, attachments);
+						m.hasText(), m.getAttachmentHeaders());
 				// TODO add text to cache when available here
-				addedHeader.postValue(h);
+				addedHeader.postEvent(h);
 			} catch (DbException e) {
 				logException(LOG, WARNING, e);
 			}
 		});
 	}
 
-	@UiThread
+	AttachmentRetriever getAttachmentRetriever() {
-	void onAddedPrivateMessageSeen() {
+		return attachmentRetriever;
-		addedHeader.setValue(null);
-	}
-
-	AttachmentController getAttachmentController() {
-		return attachmentController;
 	}
 
 	LiveData<Contact> getContact() {
@@ -380,7 +361,7 @@ public class ConversationViewModel extends AndroidViewModel {
 		return contactDeleted;
 	}
 
-	LiveData<PrivateMessageHeader> getAddedPrivateMessage() {
+	LiveEvent<PrivateMessageHeader> getAddedPrivateMessage() {
 		return addedHeader;
 	}
 

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

@@ -7,6 +7,7 @@ import android.support.annotation.UiThread;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.briar.R;
+import org.briarproject.briar.android.attachment.AttachmentItem;
 import org.briarproject.briar.api.blog.BlogInvitationRequest;
 import org.briarproject.briar.api.blog.BlogInvitationResponse;
 import org.briarproject.briar.api.conversation.ConversationMessageVisitor;

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

@@ -31,6 +31,7 @@ import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.activity.ActivityComponent;
 import org.briarproject.briar.android.activity.BriarActivity;
+import org.briarproject.briar.android.attachment.AttachmentItem;
 import org.briarproject.briar.android.util.BriarSnackbarBuilder;
 import org.briarproject.briar.android.view.PullDownLayout;
 

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

@@ -12,6 +12,7 @@ import android.view.WindowManager;
 
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.briar.R;
+import org.briarproject.briar.android.attachment.AttachmentItem;
 import org.briarproject.briar.android.conversation.glide.Radii;
 
 import java.util.ArrayList;

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

@@ -21,6 +21,7 @@ import com.github.chrisbanes.photoview.PhotoView;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.activity.BaseActivity;
+import org.briarproject.briar.android.attachment.AttachmentItem;
 import org.briarproject.briar.android.conversation.glide.GlideApp;
 
 import javax.annotation.ParametersAreNonnullByDefault;

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

@@ -11,6 +11,7 @@ import com.bumptech.glide.load.Transformation;
 
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.briar.R;
+import org.briarproject.briar.android.attachment.AttachmentItem;
 import org.briarproject.briar.android.conversation.glide.BriarImageTransformation;
 import org.briarproject.briar.android.conversation.glide.GlideApp;
 import org.briarproject.briar.android.conversation.glide.Radii;

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

@@ -13,6 +13,7 @@ import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.lifecycle.IoExecutor;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.sync.MessageId;
+import org.briarproject.briar.android.attachment.AttachmentItem;
 import org.briarproject.briar.android.viewmodel.LiveEvent;
 import org.briarproject.briar.android.viewmodel.MutableLiveEvent;
 import org.briarproject.briar.api.messaging.Attachment;

briar-android/src/main/java/org/briarproject/briar/android/conversation/glide/BriarDataFetcher.java

@@ -10,7 +10,7 @@ import org.briarproject.bramble.api.db.DatabaseExecutor;
 import org.briarproject.bramble.api.db.DbException;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.sync.MessageId;
-import org.briarproject.briar.android.conversation.AttachmentItem;
+import org.briarproject.briar.android.attachment.AttachmentItem;
 import org.briarproject.briar.api.messaging.MessagingManager;
 
 import java.io.InputStream;

briar-android/src/main/java/org/briarproject/briar/android/conversation/glide/BriarDataFetcherFactory.java

@@ -2,7 +2,7 @@ package org.briarproject.briar.android.conversation.glide;
 
 import org.briarproject.bramble.api.db.DatabaseExecutor;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
-import org.briarproject.briar.android.conversation.AttachmentItem;
+import org.briarproject.briar.android.attachment.AttachmentItem;
 import org.briarproject.briar.api.messaging.MessagingManager;
 
 import java.util.concurrent.Executor;

briar-android/src/main/java/org/briarproject/briar/android/conversation/glide/BriarGlideModule.java

@@ -10,7 +10,7 @@ import com.bumptech.glide.module.AppGlideModule;
 
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.briar.android.BriarApplication;
-import org.briarproject.briar.android.conversation.AttachmentItem;
+import org.briarproject.briar.android.attachment.AttachmentItem;
 
 import java.io.InputStream;
 

briar-android/src/main/java/org/briarproject/briar/android/conversation/glide/BriarModelLoader.java

@@ -8,7 +8,7 @@ import com.bumptech.glide.signature.ObjectKey;
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.briar.android.BriarApplication;
-import org.briarproject.briar.android.conversation.AttachmentItem;
+import org.briarproject.briar.android.attachment.AttachmentItem;
 
 import java.io.InputStream;
 

briar-android/src/main/java/org/briarproject/briar/android/conversation/glide/BriarModelLoaderFactory.java

@@ -6,7 +6,7 @@ import com.bumptech.glide.load.model.MultiModelLoaderFactory;
 
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.briar.android.BriarApplication;
-import org.briarproject.briar.android.conversation.AttachmentItem;
+import org.briarproject.briar.android.attachment.AttachmentItem;
 
 import java.io.InputStream;
 

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

@@ -1,7 +1,6 @@
 package org.briarproject.briar.android.introduction;
 
 import android.content.Context;
-import android.net.Uri;
 import android.os.Bundle;
 import android.support.annotation.Nullable;
 import android.support.v7.app.ActionBar;
@@ -26,6 +25,7 @@ import org.briarproject.briar.android.view.TextInputView;
 import org.briarproject.briar.android.view.TextSendController;
 import org.briarproject.briar.android.view.TextSendController.SendListener;
 import org.briarproject.briar.api.introduction.IntroductionManager;
+import org.briarproject.briar.api.messaging.AttachmentHeader;
 
 import java.util.List;
 import java.util.logging.Logger;
@@ -193,7 +193,8 @@ public class IntroductionMessageFragment extends BaseFragment
 	}
 
 	@Override
-	public void onSendClick(@Nullable String text, List<Uri> imageUris) {
+	public void onSendClick(@Nullable String text,
+			List<AttachmentHeader> headers) {
 		// disable button to prevent accidental double invitations
 		ui.message.setReady(false);
 

briar-android/src/main/java/org/briarproject/briar/android/reporting/CrashFragment.java

@@ -0,0 +1,40 @@
+package org.briarproject.briar.android.reporting;
+
+import android.os.Bundle;
+import android.support.annotation.Nullable;
+import android.support.v4.app.Fragment;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+
+import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
+import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
+import org.briarproject.briar.R;
+
+import static java.util.Objects.requireNonNull;
+
+@MethodsNotNullByDefault
+@ParametersNotNullByDefault
+public class CrashFragment extends Fragment {
+
+	@Nullable
+	@Override
+	public View onCreateView(LayoutInflater inflater,
+			@Nullable ViewGroup container,
+			@Nullable Bundle savedInstanceState) {
+		View v = inflater
+				.inflate(R.layout.fragment_crash, container, false);
+
+		v.findViewById(R.id.acceptButton).setOnClickListener(view ->
+				getDevReportActivity().displayFragment(true));
+		v.findViewById(R.id.declineButton).setOnClickListener(view ->
+				getDevReportActivity().closeReport());
+
+		return v;
+	}
+
+	private DevReportActivity getDevReportActivity() {
+		return (DevReportActivity) requireNonNull(getActivity());
+	}
+
+}

briar-android/src/main/java/org/briarproject/briar/android/reporting/DevReportActivity.java

@@ -1,87 +1,38 @@
 package org.briarproject.briar.android.reporting;
 
 import android.content.Context;
+import android.content.Intent;
 import android.content.res.Configuration;
-import android.os.AsyncTask;
 import android.os.Bundle;
 import android.support.annotation.Nullable;
+import android.support.v4.app.Fragment;
 import android.support.v7.app.AppCompatDelegate;
 import android.support.v7.widget.Toolbar;
-import android.view.LayoutInflater;
-import android.view.Menu;
-import android.view.MenuInflater;
-import android.view.MenuItem;
-import android.view.View;
-import android.view.inputmethod.InputMethodManager;
-import android.widget.Button;
-import android.widget.CheckBox;
-import android.widget.CompoundButton;
-import android.widget.EditText;
-import android.widget.LinearLayout;
-import android.widget.TextView;
 
-import org.acra.ReportField;
-import org.acra.collector.CrashReportData;
 import org.acra.dialog.BaseCrashReportDialog;
-import org.acra.file.CrashReportPersister;
+import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
-import org.acra.model.Element;
+import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.Localizer;
+import org.briarproject.briar.android.logout.HideUiActivity;
 import org.briarproject.briar.android.util.UserFeedback;
-import org.json.JSONException;
 
 import java.io.File;
-import java.io.IOException;
-import java.util.HashSet;
-import java.util.Iterator;
-import java.util.Map.Entry;
-import java.util.Set;
-import java.util.logging.Logger;
 
+import static android.content.Intent.FLAG_ACTIVITY_CLEAR_TASK;
+import static android.content.Intent.FLAG_ACTIVITY_NEW_TASK;
+import static android.content.Intent.FLAG_ACTIVITY_NO_ANIMATION;
 import static android.os.Build.VERSION.SDK_INT;
-import static android.view.View.GONE;
-import static android.view.View.INVISIBLE;
-import static android.view.View.VISIBLE;
 import static android.view.WindowManager.LayoutParams.FLAG_SECURE;
-import static android.view.inputmethod.InputMethodManager.SHOW_FORCED;
+import static java.util.Objects.requireNonNull;
-import static java.util.logging.Level.WARNING;
 import static org.acra.ACRAConstants.EXTRA_REPORT_FILE;
-import static org.acra.ReportField.ANDROID_VERSION;
-import static org.acra.ReportField.APP_VERSION_CODE;
-import static org.acra.ReportField.APP_VERSION_NAME;
-import static org.acra.ReportField.PACKAGE_NAME;
-import static org.acra.ReportField.REPORT_ID;
-import static org.acra.ReportField.STACK_TRACE;
 import static org.briarproject.briar.android.TestingConstants.PREVENT_SCREENSHOTS;
 
-public class DevReportActivity extends BaseCrashReportDialog
+@MethodsNotNullByDefault
-		implements CompoundButton.OnCheckedChangeListener {
+@ParametersNotNullByDefault
-
+public class DevReportActivity extends BaseCrashReportDialog {
-	private static final Logger LOG =
-			Logger.getLogger(DevReportActivity.class.getName());
-
-	private static final String STATE_REVIEWING = "reviewing";
-	private static final Set<ReportField> requiredFields = new HashSet<>();
-
-	static {
-		requiredFields.add(REPORT_ID);
-		requiredFields.add(APP_VERSION_CODE);
-		requiredFields.add(APP_VERSION_NAME);
-		requiredFields.add(PACKAGE_NAME);
-		requiredFields.add(ANDROID_VERSION);
-		requiredFields.add(STACK_TRACE);
-	}
 
 	private AppCompatDelegate delegate;
-	private Set<ReportField> excludedFields = new HashSet<>();
-	private EditText userCommentView = null;
-	private EditText userEmailView = null;
-	private CheckBox includeDebugReport = null;
-	private Button chevron = null;
-	private LinearLayout report = null;
-	private View progress = null;
-	private MenuItem sendReport = null;
-	private boolean reviewing = false;
 
 	private AppCompatDelegate getDelegate() {
 		if (delegate == null) {
@@ -110,68 +61,21 @@ public class DevReportActivity extends BaseCrashReportDialog
 	}
 
 	@Override
-	public void init(Bundle state) {
+	public void init(@Nullable Bundle state) {
 		super.init(state);
 
 		if (PREVENT_SCREENSHOTS) getWindow().addFlags(FLAG_SECURE);
 
 		getDelegate().setContentView(R.layout.activity_dev_report);
 
-		Toolbar tb = findViewById(R.id.toolbar);
+		Toolbar toolbar = findViewById(R.id.toolbar);
-		getDelegate().setSupportActionBar(tb);
+		getDelegate().setSupportActionBar(toolbar);
 
-		View requestReport = findViewById(R.id.request_report);
+		String title = getString(isFeedback() ? R.string.feedback_title :
-		View reportForm = findViewById(R.id.report_form);
+				R.string.crash_report_title);
-		userCommentView = findViewById(R.id.user_comment);
+		requireNonNull(getDelegate().getSupportActionBar()).setTitle(title);
-		userEmailView = findViewById(R.id.user_email);
-		includeDebugReport = findViewById(R.id.include_debug_report);
-		chevron = findViewById(R.id.chevron);
-		report = findViewById(R.id.report_content);
-		progress = findViewById(R.id.progress_wheel);
 
-		//noinspection ConstantConditions
+		if (state == null) displayFragment(isFeedback());
-		getDelegate().getSupportActionBar().setTitle(
-				isFeedback() ? R.string.feedback_title :
-						R.string.crash_report_title);
-		userCommentView.setHint(isFeedback() ? R.string.enter_feedback :
-				R.string.describe_crash);
-
-		if (isFeedback()) {
-			includeDebugReport
-					.setText(getString(R.string.include_debug_report_feedback));
-			reportForm.setVisibility(VISIBLE);
-			requestReport.setVisibility(INVISIBLE);
-		} else {
-			includeDebugReport.setChecked(true);
-			reportForm.setVisibility(INVISIBLE);
-			requestReport.setVisibility(VISIBLE);
-		}
-
-		findViewById(R.id.acceptButton).setOnClickListener(v -> {
-			reviewing = true;
-			reportForm.setVisibility(VISIBLE);
-			requestReport.setVisibility(INVISIBLE);
-			((InputMethodManager) getSystemService(INPUT_METHOD_SERVICE))
-					.showSoftInput(userCommentView, SHOW_FORCED);
-		});
-		findViewById(R.id.declineButton).setOnClickListener(v -> closeReport());
-		chevron.setOnClickListener(v -> {
-			boolean show =
-					chevron.getText().equals(getString(R.string.show));
-			if (show) {
-				chevron.setText(R.string.hide);
-				refresh();
-			} else {
-				chevron.setText(R.string.show);
-				report.setVisibility(GONE);
-			}
-		});
-
-		if (state != null)
-			reviewing = state.getBoolean(STATE_REVIEWING, isFeedback());
-
-		if (!isFeedback() && !reviewing)
-			requestReport.setVisibility(VISIBLE);
 	}
 
 	@Override
@@ -181,47 +85,17 @@ public class DevReportActivity extends BaseCrashReportDialog
 	}
 
 	@Override
-	public void onPostCreate(Bundle state) {
+	public void onPostCreate(@Nullable Bundle state) {
 		super.onPostCreate(state);
 		getDelegate().onPostCreate(state);
 	}
 
-	@Override
-	public void onStart() {
-		super.onStart();
-		if (chevron.isSelected()) refresh();
-	}
-
 	@Override
 	protected void onPostResume() {
 		super.onPostResume();
 		getDelegate().onPostResume();
 	}
 
-	@Override
-	public boolean onCreateOptionsMenu(Menu menu) {
-		// Inflate the menu items for use in the action bar
-		MenuInflater inflater = getDelegate().getMenuInflater();
-		inflater.inflate(R.menu.dev_report_actions, menu);
-		sendReport = menu.findItem(R.id.action_send_report);
-		return super.onCreateOptionsMenu(menu);
-	}
-
-	@Override
-	public boolean onOptionsItemSelected(MenuItem item) {
-		// Handle presses on the action bar items
-		switch (item.getItemId()) {
-			case android.R.id.home:
-				onBackPressed();
-				return true;
-			case R.id.action_send_report:
-				processReport();
-				return true;
-			default:
-				return super.onOptionsItemSelected(item);
-		}
-	}
-
 	@Override
 	public void onTitleChanged(CharSequence title, int color) {
 		super.onTitleChanged(title, color);
@@ -234,12 +108,6 @@ public class DevReportActivity extends BaseCrashReportDialog
 		getDelegate().onConfigurationChanged(newConfig);
 	}
 
-	@Override
-	public void onSaveInstanceState(Bundle state) {
-		super.onSaveInstanceState(state);
-		state.putBoolean(STATE_REVIEWING, reviewing);
-	}
-
 	@Override
 	public void onStop() {
 		super.onStop();
@@ -257,132 +125,51 @@ public class DevReportActivity extends BaseCrashReportDialog
 		closeReport();
 	}
 
-	@Override
+	void sendCrashReport(String comment, String email) {
-	public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
+		sendCrash(comment, email);
-		ReportField field = (ReportField) buttonView.getTag();
-		if (field != null) {
-			if (isChecked) excludedFields.remove(field);
-			else excludedFields.add(field);
-		}
 	}
 
-	@SuppressWarnings("ThrowableResultOfMethodCallIgnored")
 	private boolean isFeedback() {
 		return getException() instanceof UserFeedback;
 	}
 
-	private void refresh() {
+	void displayFragment(boolean showReportForm) {
-		report.setVisibility(INVISIBLE);
+		Fragment f;
-		progress.setVisibility(VISIBLE);
+		if (showReportForm) {
-		report.removeAllViews();
+			File file =
-		new AsyncTask<Void, Void, CrashReportData>() {
+					(File) getIntent().getSerializableExtra(EXTRA_REPORT_FILE);
+			f = ReportFormFragment.newInstance(isFeedback(), file);
+			requireNonNull(getDelegate().getSupportActionBar()).show();
+		} else {
+			f = new CrashFragment();
+			requireNonNull(getDelegate().getSupportActionBar()).hide();
+		}
+		getSupportFragmentManager().beginTransaction()
+				.replace(R.id.fragmentContainer, f, f.getTag())
+				.commit();
 
-			@Override
-			protected CrashReportData doInBackground(Void... args) {
-				File reportFile = (File) getIntent().getSerializableExtra(
-						EXTRA_REPORT_FILE);
-				CrashReportPersister persister = new CrashReportPersister();
-				try {
-					return persister.load(reportFile);
-				} catch (IOException | JSONException e) {
-					LOG.log(WARNING, "Could not load report file", e);
-					return null;
-				}
-			}
-
-			@Override
-			protected void onPostExecute(CrashReportData crashData) {
-				LayoutInflater inflater = getLayoutInflater();
-				if (crashData != null) {
-					for (Entry<ReportField, Element> e : crashData.entrySet()) {
-						ReportField field = e.getKey();
-						String value = e.getValue().toString()
-								.replaceAll("\\\\n", "\n");
-						boolean required = requiredFields.contains(field);
-						boolean excluded = excludedFields.contains(field);
-						View v = inflater.inflate(R.layout.list_item_crash,
-								report, false);
-						CheckBox cb = v.findViewById(R.id.include_in_report);
-						cb.setTag(field);
-						cb.setChecked(required || !excluded);
-						cb.setEnabled(!required);
-						cb.setOnCheckedChangeListener(DevReportActivity.this);
-						cb.setText(field.toString());
-						TextView content = v.findViewById(R.id.content);
-						content.setText(value);
-						report.addView(v);
-					}
-				} else {
-					View v = inflater.inflate(
-							android.R.layout.simple_list_item_1, report, false);
-					TextView error = v.findViewById(android.R.id.text1);
-					error.setText(R.string.could_not_load_report_data);
-					report.addView(v);
-				}
-				report.setVisibility(VISIBLE);
-				progress.setVisibility(GONE);
-			}
-		}.execute();
 	}
 
-	private void processReport() {
+	@Override
-		userCommentView.setEnabled(false);
+	public void invalidateOptionsMenu() {
-		userEmailView.setEnabled(false);
+		super.invalidateOptionsMenu();
-		sendReport.setEnabled(false);
+		getDelegate().invalidateOptionsMenu();
-		progress.setVisibility(VISIBLE);
-		boolean includeReport = !isFeedback() || includeDebugReport.isChecked();
-		new AsyncTask<Void, Void, Boolean>() {
-
-			@Override
-			protected Boolean doInBackground(Void... args) {
-				File reportFile = (File) getIntent().getSerializableExtra(
-						EXTRA_REPORT_FILE);
-				CrashReportPersister persister = new CrashReportPersister();
-				try {
-					CrashReportData data = persister.load(reportFile);
-					if (includeReport) {
-						for (ReportField field : excludedFields) {
-							LOG.info("Removing field " + field.name());
-							data.remove(field);
-						}
-					} else {
-						Iterator<Entry<ReportField, Element>> iter =
-								data.entrySet().iterator();
-						while (iter.hasNext()) {
-							Entry<ReportField, Element> e = iter.next();
-							if (!requiredFields.contains(e.getKey())) {
-								iter.remove();
-							}
-						}
-					}
-					persister.store(data, reportFile);
-					return true;
-				} catch (IOException | JSONException e) {
-					LOG.log(WARNING, "Error processing report file", e);
-					return false;
-				}
-			}
-
-			@Override
-			protected void onPostExecute(Boolean success) {
-				if (success) {
-					// Retrieve user's comment and email address, if any
-					String comment = "";
-					if (userCommentView != null)
-						comment = userCommentView.getText().toString();
-					String email = "";
-					if (userEmailView != null) {
-						email = userEmailView.getText().toString();
-					}
-					sendCrash(comment, email);
-				}
-				finish();
-			}
-		}.execute();
 	}
 
-	private void closeReport() {
+	void closeReport() {
 		cancelReports();
+		exit();
+	}
+
+	void exit() {
+		if (!isFeedback()) {
+			Intent i = new Intent(this, HideUiActivity.class);
+			i.addFlags(FLAG_ACTIVITY_NEW_TASK
+					| FLAG_ACTIVITY_NO_ANIMATION
+					| FLAG_ACTIVITY_CLEAR_TASK);
+			startActivity(i);
+		}
 		finish();
 	}
+
 }

briar-android/src/main/java/org/briarproject/briar/android/reporting/ReportFormFragment.java

@@ -0,0 +1,290 @@
+package org.briarproject.briar.android.reporting;
+
+import android.os.AsyncTask;
+import android.os.Bundle;
+import android.support.annotation.Nullable;
+import android.support.v4.app.Fragment;
+import android.view.LayoutInflater;
+import android.view.Menu;
+import android.view.MenuInflater;
+import android.view.MenuItem;
+import android.view.View;
+import android.view.ViewGroup;
+import android.widget.Button;
+import android.widget.CheckBox;
+import android.widget.CompoundButton;
+import android.widget.CompoundButton.OnCheckedChangeListener;
+import android.widget.EditText;
+import android.widget.LinearLayout;
+import android.widget.TextView;
+
+import org.acra.ReportField;
+import org.acra.collector.CrashReportData;
+import org.acra.file.CrashReportPersister;
+import org.acra.model.Element;
+import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
+import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
+import org.briarproject.briar.R;
+import org.json.JSONException;
+
+import java.io.File;
+import java.io.IOException;
+import java.util.HashSet;
+import java.util.Iterator;
+import java.util.Map;
+import java.util.Set;
+import java.util.logging.Logger;
+
+import static android.view.MenuItem.SHOW_AS_ACTION_ALWAYS;
+import static android.view.View.GONE;
+import static android.view.View.INVISIBLE;
+import static android.view.View.VISIBLE;
+import static java.util.Objects.requireNonNull;
+import static java.util.logging.Level.WARNING;
+import static java.util.logging.Logger.getLogger;
+import static org.acra.ACRAConstants.EXTRA_REPORT_FILE;
+import static org.acra.ReportField.ANDROID_VERSION;
+import static org.acra.ReportField.APP_VERSION_CODE;
+import static org.acra.ReportField.APP_VERSION_NAME;
+import static org.acra.ReportField.PACKAGE_NAME;
+import static org.acra.ReportField.REPORT_ID;
+import static org.acra.ReportField.STACK_TRACE;
+
+@MethodsNotNullByDefault
+@ParametersNotNullByDefault
+public class ReportFormFragment extends Fragment
+		implements OnCheckedChangeListener {
+
+	private static final Logger LOG =
+			getLogger(ReportFormFragment.class.getName());
+	private static final String IS_FEEDBACK = "isFeedback";
+	private static final Set<ReportField> requiredFields = new HashSet<>();
+	private static final Set<ReportField> excludedFields = new HashSet<>();
+	static {
+		requiredFields.add(REPORT_ID);
+		requiredFields.add(APP_VERSION_CODE);
+		requiredFields.add(APP_VERSION_NAME);
+		requiredFields.add(PACKAGE_NAME);
+		requiredFields.add(ANDROID_VERSION);
+		requiredFields.add(STACK_TRACE);
+	}
+
+	private boolean isFeedback;
+	private File reportFile;
+
+	private EditText userCommentView;
+	private EditText userEmailView;
+	private CheckBox includeDebugReport;
+	private Button chevron;
+	private LinearLayout report;
+	private View progress;
+	@Nullable
+	private MenuItem sendReport;
+
+	static ReportFormFragment newInstance(boolean isFeedback,
+			File reportFile) {
+		ReportFormFragment f = new ReportFormFragment();
+		Bundle args = new Bundle();
+		args.putBoolean(IS_FEEDBACK, isFeedback);
+		args.putSerializable(EXTRA_REPORT_FILE, reportFile);
+		f.setArguments(args);
+		return f;
+	}
+
+	@Override
+	public void onCreate(@Nullable Bundle savedInstanceState) {
+		super.onCreate(savedInstanceState);
+		setHasOptionsMenu(true);
+	}
+
+	@Nullable
+	@Override
+	public View onCreateView(LayoutInflater inflater,
+			@Nullable ViewGroup container,
+			@Nullable Bundle savedInstanceState) {
+		View v = inflater.inflate(R.layout.fragment_report_form, container,
+				false);
+
+		userCommentView = v.findViewById(R.id.user_comment);
+		userEmailView = v.findViewById(R.id.user_email);
+		includeDebugReport = v.findViewById(R.id.include_debug_report);
+		chevron = v.findViewById(R.id.chevron);
+		report = v.findViewById(R.id.report_content);
+		progress = v.findViewById(R.id.progress_wheel);
+
+		Bundle args = requireNonNull(getArguments());
+		isFeedback = args.getBoolean(IS_FEEDBACK);
+		reportFile =
+				(File) requireNonNull(args.getSerializable(EXTRA_REPORT_FILE));
+
+		if (isFeedback) {
+			includeDebugReport
+					.setText(getString(R.string.include_debug_report_feedback));
+			userCommentView.setHint(R.string.enter_feedback);
+		} else {
+			includeDebugReport.setChecked(true);
+			userCommentView.setHint(R.string.describe_crash);
+		}
+
+		chevron.setOnClickListener(view -> {
+			boolean show = chevron.getText().equals(getString(R.string.show));
+			if (show) {
+				chevron.setText(R.string.hide);
+				refresh();
+			} else {
+				chevron.setText(R.string.show);
+				report.setVisibility(GONE);
+			}
+		});
+
+		return v;
+	}
+
+	@Override
+	public void onStart() {
+		super.onStart();
+		if (chevron.isSelected()) refresh();
+	}
+
+	@Override
+	public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
+		inflater.inflate(R.menu.dev_report_actions, menu);
+		sendReport = menu.findItem(R.id.action_send_report);
+		// calling setShowAsAction() shouldn't be needed, but for some reason is
+		sendReport.setShowAsAction(SHOW_AS_ACTION_ALWAYS);
+		super.onCreateOptionsMenu(menu, inflater);
+	}
+
+	@Override
+	public boolean onOptionsItemSelected(MenuItem item) {
+		if (item.getItemId() == R.id.action_send_report) {
+			processReport();
+			return true;
+		}
+		return super.onOptionsItemSelected(item);
+	}
+
+	@Override
+	public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
+		ReportField field = (ReportField) buttonView.getTag();
+		if (field != null) {
+			if (isChecked) excludedFields.remove(field);
+			else excludedFields.add(field);
+		}
+	}
+
+	private void refresh() {
+		report.setVisibility(INVISIBLE);
+		progress.setVisibility(VISIBLE);
+		report.removeAllViews();
+		new AsyncTask<Void, Void, CrashReportData>() {
+
+			@Override
+			protected CrashReportData doInBackground(Void... args) {
+				CrashReportPersister persister = new CrashReportPersister();
+				try {
+					return persister.load(reportFile);
+				} catch (IOException | JSONException e) {
+					LOG.log(WARNING, "Could not load report file", e);
+					return null;
+				}
+			}
+
+			@Override
+			protected void onPostExecute(CrashReportData crashData) {
+				LayoutInflater inflater = getLayoutInflater();
+				if (crashData != null) {
+					for (Map.Entry<ReportField, Element> e : crashData
+							.entrySet()) {
+						ReportField field = e.getKey();
+						StringBuilder valueBuilder = new StringBuilder();
+						for (String pair : e.getValue().flatten()) {
+							valueBuilder.append(pair).append("\n");
+						}
+						String value = valueBuilder.toString();
+						boolean required = requiredFields.contains(field);
+						boolean excluded = excludedFields.contains(field);
+						View v = inflater.inflate(R.layout.list_item_crash,
+								report, false);
+						CheckBox cb = v.findViewById(R.id.include_in_report);
+						cb.setTag(field);
+						cb.setChecked(required || !excluded);
+						cb.setEnabled(!required);
+						cb.setOnCheckedChangeListener(ReportFormFragment.this);
+						cb.setText(field.toString());
+						TextView content = v.findViewById(R.id.content);
+						content.setText(value);
+						report.addView(v);
+					}
+				} else {
+					View v = inflater.inflate(
+							android.R.layout.simple_list_item_1, report, false);
+					TextView error = v.findViewById(android.R.id.text1);
+					error.setText(R.string.could_not_load_report_data);
+					report.addView(v);
+				}
+				report.setVisibility(VISIBLE);
+				progress.setVisibility(GONE);
+			}
+		}.execute();
+	}
+
+	private void processReport() {
+		userCommentView.setEnabled(false);
+		userEmailView.setEnabled(false);
+		requireNonNull(sendReport).setEnabled(false);
+		progress.setVisibility(VISIBLE);
+		boolean includeReport = !isFeedback || includeDebugReport.isChecked();
+		new AsyncTask<Void, Void, Boolean>() {
+
+			@Override
+			protected Boolean doInBackground(Void... args) {
+				CrashReportPersister persister = new CrashReportPersister();
+				try {
+					CrashReportData data = persister.load(reportFile);
+					if (includeReport) {
+						for (ReportField field : excludedFields) {
+							LOG.info("Removing field " + field.name());
+							data.remove(field);
+						}
+					} else {
+						Iterator<Map.Entry<ReportField, Element>> iter =
+								data.entrySet().iterator();
+						while (iter.hasNext()) {
+							Map.Entry<ReportField, Element> e = iter.next();
+							if (!requiredFields.contains(e.getKey())) {
+								iter.remove();
+							}
+						}
+					}
+					persister.store(data, reportFile);
+					return true;
+				} catch (IOException | JSONException e) {
+					LOG.log(WARNING, "Error processing report file", e);
+					return false;
+				}
+			}
+
+			@Override
+			protected void onPostExecute(Boolean success) {
+				if (success) {
+					// Retrieve user's comment and email address, if any
+					String comment = "";
+					if (userCommentView != null)
+						comment = userCommentView.getText().toString();
+					String email = "";
+					if (userEmailView != null) {
+						email = userEmailView.getText().toString();
+					}
+					getDevReportActivity().sendCrashReport(comment, email);
+				}
+				if (getActivity() != null) getDevReportActivity().exit();
+			}
+		}.execute();
+	}
+
+	private DevReportActivity getDevReportActivity() {
+		return (DevReportActivity) requireNonNull(getActivity());
+	}
+
+}

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

@@ -1,7 +1,6 @@
 package org.briarproject.briar.android.sharing;
 
 import android.content.Context;
-import android.net.Uri;
 import android.os.Bundle;
 import android.support.annotation.Nullable;
 import android.support.annotation.StringRes;
@@ -19,6 +18,7 @@ import org.briarproject.briar.android.fragment.BaseFragment;
 import org.briarproject.briar.android.view.LargeTextInputView;
 import org.briarproject.briar.android.view.TextSendController;
 import org.briarproject.briar.android.view.TextSendController.SendListener;
+import org.briarproject.briar.api.messaging.AttachmentHeader;
 
 import java.util.List;
 
@@ -83,7 +83,8 @@ public abstract class BaseMessageFragment extends BaseFragment
 	}
 
 	@Override
-	public void onSendClick(@Nullable String text, List<Uri> imageUris) {
+	public void onSendClick(@Nullable String text,
+			List<AttachmentHeader> headers) {
 		// disable button to prevent accidental double actions
 		sendController.setReady(false);
 		message.hideSoftKeyboard();

briar-android/src/main/java/org/briarproject/briar/android/threaded/ThreadListActivity.java

@@ -1,7 +1,6 @@
 package org.briarproject.briar.android.threaded;
 
 import android.content.Intent;
-import android.net.Uri;
 import android.os.Bundle;
 import android.os.Parcelable;
 import android.support.annotation.CallSuper;
@@ -34,6 +33,7 @@ import org.briarproject.briar.android.view.TextSendController;
 import org.briarproject.briar.android.view.TextSendController.SendListener;
 import org.briarproject.briar.android.view.UnreadMessageButton;
 import org.briarproject.briar.api.client.NamedGroup;
+import org.briarproject.briar.api.messaging.AttachmentHeader;
 
 import java.util.Collection;
 import java.util.List;
@@ -341,7 +341,8 @@ public abstract class ThreadListActivity<G extends NamedGroup, I extends ThreadI
 	}
 
 	@Override
-	public void onSendClick(@Nullable String text, List<Uri> imageUris) {
+	public void onSendClick(@Nullable String text,
+			List<AttachmentHeader> headers) {
 		if (isNullOrEmpty(text)) throw new AssertionError();
 
 		I replyItem = adapter.getHighlightedItem();

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

@@ -1,7 +1,6 @@
 package org.briarproject.briar.android.view;
 
 import android.content.Context;
-import android.net.Uri;
 import android.support.annotation.Nullable;
 import android.support.constraint.ConstraintLayout;
 import android.support.v7.widget.RecyclerView;
@@ -10,11 +9,13 @@ import android.view.LayoutInflater;
 
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.briar.R;
+import org.briarproject.briar.android.attachment.AttachmentItemResult;
 
 import java.util.Collection;
 
 import static android.content.Context.LAYOUT_INFLATER_SERVICE;
 import static android.support.v4.content.ContextCompat.getColor;
+import static android.support.v7.widget.RecyclerView.NO_POSITION;
 import static android.view.ViewGroup.LayoutParams.MATCH_PARENT;
 import static java.util.Objects.requireNonNull;
 
@@ -60,34 +61,28 @@ public class ImagePreview extends ConstraintLayout {
 		this.listener = listener;
 	}
 
-	void showPreview(Collection<Uri> imageUris) {
+	void showPreview(Collection<ImagePreviewItem> items) {
 		if (listener == null) throw new IllegalStateException();
-		if (imageUris.size() == 1) {
+		if (items.size() == 1) {
 			LayoutParams params = (LayoutParams) imageList.getLayoutParams();
 			params.width = MATCH_PARENT;
 			imageList.setLayoutParams(params);
 		}
 		setVisibility(VISIBLE);
-		imageList.setAdapter(new ImagePreviewAdapter(imageUris, listener));
+		ImagePreviewAdapter adapter = new ImagePreviewAdapter(items);
+		imageList.setAdapter(adapter);
 	}
 
-	void removeUri(Uri uri) {
+	void loadPreviewImage(AttachmentItemResult result) {
 		ImagePreviewAdapter adapter =
-				(ImagePreviewAdapter) imageList.getAdapter();
+				((ImagePreviewAdapter) imageList.getAdapter());
-		requireNonNull(adapter).removeUri(uri);
+		int pos = requireNonNull(adapter).loadItemPreview(result);
+		if (pos != NO_POSITION) {
+			imageList.smoothScrollToPosition(pos);
+		}
 	}
 
 	interface ImagePreviewListener {
-
-		void onPreviewLoaded();
-
-		/**
-		 * Called when Glide can't load a preview image.
-		 *
-		 * Warning: Glide may call this multiple times.
-		 */
-		void onUriError(Uri uri);
-
 		void onCancel();
 	}
 

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

@@ -1,6 +1,5 @@
 package org.briarproject.briar.android.view;
 
-import android.net.Uri;
 import android.support.annotation.LayoutRes;
 import android.support.v7.widget.RecyclerView.Adapter;
 import android.view.LayoutInflater;
@@ -9,25 +8,24 @@ import android.view.ViewGroup;
 
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.briar.R;
-import org.briarproject.briar.android.view.ImagePreview.ImagePreviewListener;
+import org.briarproject.briar.android.attachment.AttachmentItemResult;
 
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.List;
 
+import static android.support.v7.widget.RecyclerView.NO_POSITION;
 import static java.util.Objects.requireNonNull;
 
 @NotNullByDefault
 class ImagePreviewAdapter extends Adapter<ImagePreviewViewHolder> {
 
-	private final List<Uri> items;
+	private final List<ImagePreviewItem> items;
-	private final ImagePreviewListener listener;
 	@LayoutRes
 	private final int layout;
 
-	ImagePreviewAdapter(Collection<Uri> items, ImagePreviewListener listener) {
+	ImagePreviewAdapter(Collection<ImagePreviewItem> items) {
 		this.items = new ArrayList<>(items);
-		this.listener = listener;
 		this.layout = items.size() == 1 ?
 				R.layout.list_item_image_preview_single :
 				R.layout.list_item_image_preview;
@@ -38,7 +36,7 @@ class ImagePreviewAdapter extends Adapter<ImagePreviewViewHolder> {
 			int type) {
 		View v = LayoutInflater.from(viewGroup.getContext())
 				.inflate(layout, viewGroup, false);
-		return new ImagePreviewViewHolder(v, requireNonNull(listener));
+		return new ImagePreviewViewHolder(v);
 	}
 
 	@Override
@@ -52,11 +50,17 @@ class ImagePreviewAdapter extends Adapter<ImagePreviewViewHolder> {
 		return items.size();
 	}
 
-	void removeUri(Uri uri) {
+	int loadItemPreview(AttachmentItemResult result) {
-		int pos = items.indexOf(uri);
+		ImagePreviewItem newItem = new ImagePreviewItem(result.getUri());
-		if (pos == -1) return;
+		int pos = items.indexOf(newItem);
-		items.remove(uri);
+		if (pos == NO_POSITION) throw new AssertionError();
-		notifyItemRemoved(pos);
+		ImagePreviewItem item = items.get(pos);
+		if (item.getItem() == null) {
+			item.setItem(requireNonNull(result.getItem()));
+			notifyItemChanged(pos, item);
+			return pos;
+		}
+		return NO_POSITION;
 	}
 
 }

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

@@ -0,0 +1,53 @@
+package org.briarproject.briar.android.view;
+
+import android.net.Uri;
+import android.support.annotation.Nullable;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.briar.android.attachment.AttachmentItem;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.List;
+
+@NotNullByDefault
+class ImagePreviewItem {
+
+	private final Uri uri;
+	@Nullable
+	private AttachmentItem item;
+
+	ImagePreviewItem(Uri uri) {
+		this.uri = uri;
+		this.item = null;
+	}
+
+	static List<ImagePreviewItem> fromUris(Collection<Uri> uris) {
+		List<ImagePreviewItem> items = new ArrayList<>(uris.size());
+		for (Uri uri : uris) {
+			items.add(new ImagePreviewItem(uri));
+		}
+		return items;
+	}
+
+	public void setItem(AttachmentItem item) {
+		this.item = item;
+	}
+
+	@Nullable
+	public AttachmentItem getItem() {
+		return item;
+	}
+
+	@Override
+	public boolean equals(@Nullable Object o) {
+		return o instanceof ImagePreviewItem &&
+				uri.equals(((ImagePreviewItem) o).uri);
+	}
+
+	@Override
+	public int hashCode() {
+		return uri.hashCode();
+	}
+
+}

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

@@ -1,7 +1,6 @@
 package org.briarproject.briar.android.view;
 
 import android.graphics.drawable.Drawable;
-import android.net.Uri;
 import android.support.annotation.DrawableRes;
 import android.support.annotation.Nullable;
 import android.support.v7.widget.RecyclerView.ViewHolder;
@@ -17,9 +16,9 @@ import com.bumptech.glide.request.target.Target;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.conversation.glide.GlideApp;
-import org.briarproject.briar.android.view.ImagePreview.ImagePreviewListener;
 
 import static android.view.View.INVISIBLE;
+import static android.view.View.VISIBLE;
 import static com.bumptech.glide.load.engine.DiskCacheStrategy.NONE;
 import static com.bumptech.glide.load.resource.bitmap.DownsampleStrategy.FIT_CENTER;
 import static com.bumptech.glide.load.resource.drawable.DrawableTransitionOptions.withCrossFade;
@@ -30,45 +29,47 @@ class ImagePreviewViewHolder extends ViewHolder {
 	@DrawableRes
 	private static final int ERROR_RES = R.drawable.ic_image_broken;
 
-	private final ImagePreviewListener listener;
-
 	private final ImageView imageView;
 	private final ProgressBar progressBar;
 
-	ImagePreviewViewHolder(View v, ImagePreviewListener listener) {
+	ImagePreviewViewHolder(View v) {
 		super(v);
-		this.listener = listener;
 		this.imageView = v.findViewById(R.id.imageView);
 		this.progressBar = v.findViewById(R.id.progressBar);
 	}
 
-	void bind(Uri uri) {
+	void bind(ImagePreviewItem item) {
-		GlideApp.with(imageView)
+		if (item.getItem() == null) {
-				.load(uri)
+			progressBar.setVisibility(VISIBLE);
-				.diskCacheStrategy(NONE)
+			GlideApp.with(imageView)
-				.error(ERROR_RES)
+					.clear(imageView);
-				.downsample(FIT_CENTER)
+		} else {
-				.transition(withCrossFade())
+			GlideApp.with(imageView)
-				.addListener(new RequestListener<Drawable>() {
+					.load(item.getItem())
-					@Override
+					.diskCacheStrategy(NONE)
-					public boolean onLoadFailed(@Nullable GlideException e,
+					.error(ERROR_RES)
-							Object model, Target<Drawable> target,
+					.downsample(FIT_CENTER)
-							boolean isFirstResource) {
+					.transition(withCrossFade())
-						progressBar.setVisibility(INVISIBLE);
+					.addListener(new RequestListener<Drawable>() {
-						listener.onUriError(uri);
+						@Override
-						return false;
+						public boolean onLoadFailed(@Nullable GlideException e,
-					}
+								Object model, Target<Drawable> target,
+								boolean isFirstResource) {
+							progressBar.setVisibility(INVISIBLE);
+							return false;
+						}
 
-					@Override
+						@Override
-					public boolean onResourceReady(Drawable resource,
+						public boolean onResourceReady(Drawable resource,
-							Object model, Target<Drawable> target,
+								Object model, Target<Drawable> target,
-							DataSource dataSource, boolean isFirstResource) {
+								DataSource dataSource,
-						progressBar.setVisibility(INVISIBLE);
+								boolean isFirstResource) {
-						listener.onPreviewLoaded();
+							progressBar.setVisibility(INVISIBLE);
-						return false;
+							return false;
-					}
+						}
-				})
+					})
-				.into(imageView);
+					.into(imageView);
+		}
 	}
 
 }

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

@@ -1,6 +1,9 @@
 package org.briarproject.briar.android.view;
 
 import android.app.Activity;
+import android.arch.lifecycle.LifecycleOwner;
+import android.arch.lifecycle.LiveData;
+import android.arch.lifecycle.Observer;
 import android.content.ClipData;
 import android.content.Context;
 import android.content.Intent;
@@ -15,26 +18,36 @@ import android.widget.Toast;
 
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.briar.R;
+import org.briarproject.briar.android.attachment.AttachmentItemResult;
+import org.briarproject.briar.android.attachment.AttachmentManager;
+import org.briarproject.briar.android.attachment.AttachmentResult;
 import org.briarproject.briar.android.view.ImagePreview.ImagePreviewListener;
+import org.briarproject.briar.api.messaging.FileTooBigException;
+import org.jsoup.UnsupportedMimeTypeException;
 
 import java.util.ArrayList;
+import java.util.Collection;
 import java.util.List;
 
 import uk.co.samuelwall.materialtaptargetprompt.MaterialTapTargetPrompt;
 import uk.co.samuelwall.materialtaptargetprompt.MaterialTapTargetPrompt.PromptStateChangeListener;
 
+import static android.arch.lifecycle.Lifecycle.State.DESTROYED;
 import static android.content.Intent.ACTION_GET_CONTENT;
 import static android.content.Intent.ACTION_OPEN_DOCUMENT;
 import static android.content.Intent.CATEGORY_OPENABLE;
 import static android.content.Intent.EXTRA_ALLOW_MULTIPLE;
+import static android.content.Intent.EXTRA_MIME_TYPES;
 import static android.os.Build.VERSION.SDK_INT;
 import static android.support.v4.content.ContextCompat.getColor;
 import static android.support.v4.view.AbsSavedState.EMPTY_STATE;
 import static android.view.View.GONE;
 import static android.widget.Toast.LENGTH_LONG;
-import static java.util.Collections.emptyList;
 import static java.util.Objects.requireNonNull;
 import static org.briarproject.briar.android.util.UiUtils.resolveColorAttribute;
+import static org.briarproject.briar.api.messaging.MessagingConstants.IMAGE_MIME_TYPES;
+import static org.briarproject.briar.api.messaging.MessagingConstants.MAX_ATTACHMENTS_PER_MESSAGE;
+import static org.briarproject.briar.api.messaging.MessagingConstants.MAX_IMAGE_SIZE;
 import static uk.co.samuelwall.materialtaptargetprompt.MaterialTapTargetPrompt.STATE_DISMISSED;
 import static uk.co.samuelwall.materialtaptargetprompt.MaterialTapTargetPrompt.STATE_FINISHED;
 
@@ -44,19 +57,21 @@ public class TextAttachmentController extends TextSendController
 		implements ImagePreviewListener {
 
 	private final ImagePreview imagePreview;
-	private final AttachImageListener imageListener;
+	private final AttachmentListener attachmentListener;
 	private final CompositeSendButton sendButton;
+	private final AttachmentManager attachmentManager;
 
-	private CharSequence textHint;
+	private final List<Uri> imageUris = new ArrayList<>();
-	private List<Uri> imageUris = emptyList();
+	private final CharSequence textHint;
-	private int previewsLoaded = 0;
+	private boolean loadingUris = false;
-	private boolean loadingPreviews = false;
 
 	public TextAttachmentController(TextInputView v, ImagePreview imagePreview,
-			SendListener listener, AttachImageListener imageListener) {
+			AttachmentListener attachmentListener,
-		super(v, listener, false);
+			AttachmentManager attachmentManager) {
-		this.imageListener = imageListener;
+		super(v, attachmentListener, false);
+		this.attachmentListener = attachmentListener;
 		this.imagePreview = imagePreview;
+		this.attachmentManager = attachmentManager;
 		this.imagePreview.setImagePreviewListener(this);
 
 		sendButton = (CompositeSendButton) compositeSendButton;
@@ -67,10 +82,10 @@ public class TextAttachmentController extends TextSendController
 
 	@Override
 	protected void updateViewState() {
-		textInput.setEnabled(ready && !loadingPreviews);
+		textInput.setEnabled(ready && !loadingUris);
-		boolean sendEnabled = ready && !loadingPreviews &&
+		boolean sendEnabled = ready && !loadingUris &&
 				(!textIsEmpty || canSendEmptyText());
-		if (loadingPreviews) {
+		if (loadingUris) {
 			sendButton.showProgress(true);
 		} else if (imageUris.isEmpty()) {
 			sendButton.showProgress(false);
@@ -84,7 +99,9 @@ public class TextAttachmentController extends TextSendController
 	@Override
 	public void onSendEvent() {
 		if (canSend()) {
-			listener.onSendClick(textInput.getText(), imageUris);
+			if (loadingUris) throw new AssertionError();
+			listener.onSendClick(textInput.getText(),
+					attachmentManager.getAttachmentHeadersForSending());
 			reset();
 		}
 	}
@@ -110,36 +127,101 @@ public class TextAttachmentController extends TextSendController
 			builder.show();
 			return;
 		}
-		Intent intent = new Intent(SDK_INT >= 19 ?
+		Intent intent = getAttachFileIntent();
-				ACTION_OPEN_DOCUMENT : ACTION_GET_CONTENT);
+		if (attachmentListener.getLifecycle().getCurrentState() != DESTROYED) {
-		intent.addCategory(CATEGORY_OPENABLE);
+			attachmentListener.onAttachImage(intent);
-		intent.setType("image/*");
-		if (SDK_INT >= 18) intent.putExtra(EXTRA_ALLOW_MULTIPLE, true);
-		requireNonNull(imageListener).onAttachImage(intent);
-	}
-
-	public void onImageReceived(@Nullable Intent resultData) {
-		if (resultData == null) return;
-		if (resultData.getData() != null) {
-			imageUris = new ArrayList<>(1);
-			imageUris.add(resultData.getData());
-			onNewUris();
-		} else if (SDK_INT >= 18 && resultData.getClipData() != null) {
-			ClipData clipData = resultData.getClipData();
-			imageUris = new ArrayList<>(clipData.getItemCount());
-			for (int i = 0; i < clipData.getItemCount(); i++) {
-				imageUris.add(clipData.getItemAt(i).getUri());
-			}
-			onNewUris();
 		}
 	}
 
-	private void onNewUris() {
+	private Intent getAttachFileIntent() {
-		if (imageUris.isEmpty()) return;
+		Intent intent = new Intent(SDK_INT >= 19 ?
-		loadingPreviews = true;
+				ACTION_OPEN_DOCUMENT : ACTION_GET_CONTENT);
+		intent.setType("image/*");
+		intent.addCategory(CATEGORY_OPENABLE);
+		if (SDK_INT >= 19) intent.putExtra(EXTRA_MIME_TYPES, IMAGE_MIME_TYPES);
+		if (SDK_INT >= 18) intent.putExtra(EXTRA_ALLOW_MULTIPLE, true);
+		return intent;
+	}
+
+	/**
+	 * This is called with the result Intent
+	 * returned by the Activity started with {@link #getAttachFileIntent()}.
+	 * <p>
+	 * This method must be called at most once per call to
+	 * {@link AttachmentListener#onAttachImage(Intent)}.
+	 * Normally, this is true if called from
+	 * {@link Activity#onActivityResult(int, int, Intent)} since this is called
+	 * at most once per call to
+	 * {@link Activity#startActivityForResult(Intent, int)}.
+	 */
+	@SuppressWarnings("JavadocReference")
+	public void onImageReceived(@Nullable Intent resultData) {
+		if (resultData == null) return;
+		if (loadingUris || !imageUris.isEmpty()) throw new AssertionError();
+		List<Uri> newUris = new ArrayList<>();
+		if (resultData.getData() != null) {
+			newUris.add(resultData.getData());
+			onNewUris(false, newUris);
+		} else if (SDK_INT >= 18 && resultData.getClipData() != null) {
+			ClipData clipData = resultData.getClipData();
+			for (int i = 0; i < clipData.getItemCount(); i++) {
+				newUris.add(clipData.getItemAt(i).getUri());
+			}
+			onNewUris(false, newUris);
+		}
+	}
+
+	private void onNewUris(boolean restart, List<Uri> newUris) {
+		if (newUris.isEmpty()) return;
+		if (loadingUris) throw new AssertionError();
+		loadingUris = true;
+		if (newUris.size() > MAX_ATTACHMENTS_PER_MESSAGE) {
+			newUris = newUris.subList(0, MAX_ATTACHMENTS_PER_MESSAGE);
+			attachmentListener.onTooManyAttachments();
+		}
+		imageUris.addAll(newUris);
 		updateViewState();
 		textInput.setHint(R.string.image_caption_hint);
-		imagePreview.showPreview(imageUris);
+		List<ImagePreviewItem> items = ImagePreviewItem.fromUris(imageUris);
+		imagePreview.showPreview(items);
+		// store attachments and show preview when successful
+		LiveData<AttachmentResult> result =
+				attachmentManager.storeAttachments(imageUris, restart);
+		result.observe(attachmentListener, new Observer<AttachmentResult>() {
+			@Override
+			public void onChanged(@Nullable AttachmentResult attachmentResult) {
+				requireNonNull(attachmentResult);
+				boolean finished = attachmentResult.isFinished();
+				boolean success = attachmentResult.isSuccess();
+				if (finished) {
+					result.removeObserver(this);
+					if (!success) return;
+				}
+				boolean noError = onNewAttachmentItemResults(
+						attachmentResult.getItemResults());
+				if (noError && success) onAllAttachmentsCreated();
+			}
+		});
+	}
+
+	private boolean onNewAttachmentItemResults(
+			Collection<AttachmentItemResult> itemResults) {
+		if (!loadingUris) throw new AssertionError();
+		for (AttachmentItemResult result : itemResults) {
+			if (result.hasError()) {
+				onError(requireNonNull(result.getException()));
+				return false;
+			} else {
+				imagePreview.loadPreviewImage(result);
+			}
+		}
+		return true;
+	}
+
+	private void onAllAttachmentsCreated() {
+		if (!loadingUris) throw new AssertionError();
+		loadingUris = false;
+		updateViewState();
 	}
 
 	private void reset() {
@@ -148,10 +230,9 @@ public class TextAttachmentController extends TextSendController
 		// hide image layout
 		imagePreview.setVisibility(GONE);
 		// reset image URIs
-		imageUris = emptyList();
+		imageUris.clear();
-		// no preview has been loaded
+		// definitely not loading anymore
-		previewsLoaded = 0;
+		loadingUris = false;
-		loadingPreviews = false;
 		// show the image button again, so images can get attached
 		updateViewState();
 	}
@@ -168,45 +249,36 @@ public class TextAttachmentController extends TextSendController
 	@Nullable
 	public Parcelable onRestoreInstanceState(Parcelable inState) {
 		SavedState state = (SavedState) inState;
-		imageUris = requireNonNull(state.imageUris);
+		if (!imageUris.isEmpty()) throw new AssertionError();
-		onNewUris();
+		if (state.imageUris != null) onNewUris(true, state.imageUris);
 		return state.getSuperState();
 	}
 
-	@Override
+	@UiThread
-	public void onPreviewLoaded() {
+	private void onError(Exception e) {
-		previewsLoaded++;
+		String errorMsg;
-		checkAllPreviewsLoaded();
+		Context ctx = imagePreview.getContext();
-	}
+		if (e instanceof UnsupportedMimeTypeException) {
-
+			String mimeType = ((UnsupportedMimeTypeException) e).getMimeType();
-	@Override
+			errorMsg = ctx.getString(
-	public void onUriError(Uri uri) {
+					R.string.image_attach_error_invalid_mime_type, mimeType);
-		boolean removed = imageUris.remove(uri);
+		} else if (e instanceof FileTooBigException) {
-		if (!removed) {
+			int mb = MAX_IMAGE_SIZE / 1024 / 1024;
-			// we have removed this Uri already, do not remove it again
+			errorMsg = ctx.getString(R.string.image_attach_error_too_big, mb);
-			return;
+		} else {
+			errorMsg = ctx.getString(R.string.image_attach_error);
 		}
-		imagePreview.removeUri(uri);
+		Toast.makeText(ctx, errorMsg, LENGTH_LONG).show();
-		if (imageUris.isEmpty()) onCancel();
+		onCancel();
-		Toast.makeText(textInput.getContext(), R.string.image_attach_error,
-				LENGTH_LONG).show();
-		checkAllPreviewsLoaded();
 	}
 
 	@Override
 	public void onCancel() {
 		textInput.clearText();
+		attachmentManager.cancel();
 		reset();
 	}
 
-	private void checkAllPreviewsLoaded() {
-		if (previewsLoaded == imageUris.size()) {
-			loadingPreviews = false;
-			// all previews were loaded
-			updateViewState();
-		}
-	}
-
 	public void showImageOnboarding(Activity activity,
 			Runnable onOnboardingSeen) {
 		PromptStateChangeListener listener = (prompt, state) -> {
@@ -261,8 +333,11 @@ public class TextAttachmentController extends TextSendController
 				};
 	}
 
-	public interface AttachImageListener {
+	@UiThread
-		void onAttachImage(Intent intent);
+	public interface AttachmentListener extends SendListener, LifecycleOwner {
-	}
 
+		void onAttachImage(Intent intent);
+
+		void onTooManyAttachments();
+	}
 }

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

@@ -1,6 +1,5 @@
 package org.briarproject.briar.android.view;
 
-import android.net.Uri;
 import android.os.Parcelable;
 import android.support.annotation.Nullable;
 import android.support.annotation.UiThread;
@@ -10,6 +9,7 @@ import android.view.View;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.view.EmojiTextInputView.TextInputListener;
+import org.briarproject.briar.api.messaging.AttachmentHeader;
 
 import java.util.List;
 
@@ -84,8 +84,9 @@ public class TextSendController implements TextInputListener {
 		return state;
 	}
 
+	@UiThread
 	public interface SendListener {
-		void onSendClick(@Nullable String text, List<Uri> imageUris);
+		void onSendClick(@Nullable String text, List<AttachmentHeader> headers);
 	}
 
 }

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

@@ -0,0 +1,9 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+        android:width="128dp"
+        android:height="128dp"
+        android:viewportHeight="24.0"
+        android:viewportWidth="24.0">
+	<path
+		android:fillColor="#FF000000"
+		android:pathData="M11.99,2C6.47,2 2,6.47 2,12s4.47,10 9.99,10S22,17.53 22,12 17.52,2 11.99,2zM12,20c-4.42,0 -8,-3.58 -8,-8s3.58,-8 8,-8 8,3.58 8,8 -3.58,8 -8,8zM16.18,7.76l-1.06,1.06 -1.06,-1.06L13,8.82l1.06,1.06L13,10.94 14.06,12l1.06,-1.06L16.18,12l1.06,-1.06 -1.06,-1.06 1.06,-1.06zM7.82,12l1.06,-1.06L9.94,12 11,10.94 9.94,9.88 11,8.82 9.94,7.76 8.88,8.82 7.82,7.76 6.76,8.82l1.06,1.06 -1.06,1.06zM12,14c-2.33,0 -4.31,1.46 -5.11,3.5h10.22c-0.8,-2.04 -2.78,-3.5 -5.11,-3.5z"/>
+</vector>

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

@@ -1,224 +1,19 @@
 <?xml version="1.0" encoding="utf-8"?>
-<FrameLayout
+<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">
+	android:layout_height="match_parent"
+	android:orientation="vertical">
 
-	<android.support.constraint.ConstraintLayout
+	<include
-		android:id="@+id/report_form"
+		android:id="@+id/appBar"
+		layout="@layout/toolbar"
 		android:layout_width="match_parent"
-		android:layout_height="match_parent"
+		android:layout_height="wrap_content"/>
-		android:visibility="visible"
-		tools:context=".android.reporting.DevReportActivity"
-		tools:visibility="invisible">
 
-		<include
+	<FrameLayout
-			android:id="@+id/appBar"
+		android:id="@+id/fragmentContainer"
-			layout="@layout/toolbar"
-			android:layout_width="0dp"
-			android:layout_height="wrap_content"
-			app:layout_constraintEnd_toEndOf="parent"
-			app:layout_constraintStart_toStartOf="parent"
-			app:layout_constraintTop_toTopOf="parent"/>
-
-		<android.support.design.widget.TextInputLayout
-			android:id="@+id/user_comment_layout"
-			android:layout_width="0dp"
-			android:layout_height="wrap_content"
-			android:layout_marginEnd="@dimen/margin_large"
-			android:layout_marginLeft="@dimen/margin_large"
-			android:layout_marginRight="@dimen/margin_large"
-			android:layout_marginStart="@dimen/margin_large"
-			android:layout_marginTop="@dimen/margin_large"
-			app:hintEnabled="false"
-			app:layout_constraintEnd_toEndOf="parent"
-			app:layout_constraintStart_toStartOf="parent"
-			app:layout_constraintTop_toBottomOf="@+id/appBar">
-
-			<android.support.design.widget.TextInputEditText
-				android:id="@+id/user_comment"
-				android:layout_width="match_parent"
-				android:layout_height="wrap_content"
-				android:inputType="textMultiLine|textCapSentences"
-				android:maxLines="5"
-				tools:hint="@string/describe_crash"/>
-
-		</android.support.design.widget.TextInputLayout>
-
-		<android.support.design.widget.TextInputLayout
-			android:id="@+id/user_email_layout"
-			android:layout_width="0dp"
-			android:layout_height="wrap_content"
-			android:layout_marginEnd="@dimen/margin_large"
-			android:layout_marginLeft="@dimen/margin_large"
-			android:layout_marginRight="@dimen/margin_large"
-			android:layout_marginStart="@dimen/margin_large"
-			app:hintEnabled="false"
-			app:layout_constraintEnd_toEndOf="parent"
-			app:layout_constraintStart_toStartOf="parent"
-			app:layout_constraintTop_toBottomOf="@+id/user_comment_layout">
-
-			<android.support.design.widget.TextInputEditText
-				android:id="@+id/user_email"
-				android:layout_width="match_parent"
-				android:layout_height="wrap_content"
-				android:hint="@string/optional_contact_email"
-				android:inputType="textEmailAddress"
-				android:maxLines="1"/>
-
-		</android.support.design.widget.TextInputLayout>
-
-		<CheckBox
-			android:id="@+id/include_debug_report"
-			android:layout_width="0dp"
-			android:layout_height="wrap_content"
-			android:layout_marginLeft="@dimen/margin_large"
-			android:layout_marginStart="@dimen/margin_large"
-			android:checked="false"
-			android:text="@string/include_debug_report_crash"
-			app:layout_constraintBottom_toBottomOf="@+id/chevron"
-			app:layout_constraintEnd_toStartOf="@+id/chevron"
-			app:layout_constraintStart_toStartOf="parent"
-			app:layout_constraintTop_toTopOf="@+id/chevron"/>
-
-		<Button
-			android:id="@+id/chevron"
-			style="@style/BriarButtonFlat.Positive"
-			android:layout_width="wrap_content"
-			android:layout_height="wrap_content"
-			android:text="@string/show"
-			app:layout_constraintEnd_toEndOf="parent"
-			app:layout_constraintTop_toBottomOf="@+id/user_email_layout"/>
-
-		<ScrollView
-			android:id="@+id/report_scroll"
-			android:layout_width="match_parent"
-			android:layout_height="wrap_content"
-			app:layout_constraintStart_toStartOf="parent"
-			app:layout_constraintTop_toBottomOf="@id/include_debug_report">
-
-			<LinearLayout
-				android:id="@+id/report_content"
-				android:layout_width="match_parent"
-				android:layout_height="wrap_content"
-				android:gravity="center_horizontal"
-				android:orientation="vertical"
-				android:paddingBottom="@dimen/listitem_height_one_line_avatar"
-				android:paddingEnd="@dimen/margin_large"
-				android:paddingStart="@dimen/margin_large"
-				android:paddingTop="@dimen/margin_small"
-				android:visibility="gone"
-				tools:visibility="visible"/>
-
-		</ScrollView>
-
-		<ProgressBar
-			android:id="@+id/progress_wheel"
-			style="?android:attr/progressBarStyleLarge"
-			android:layout_width="wrap_content"
-			android:layout_height="wrap_content"
-			android:indeterminate="true"
-			android:visibility="gone"
-			app:layout_constraintBottom_toBottomOf="parent"
-			app:layout_constraintEnd_toEndOf="parent"
-			app:layout_constraintStart_toStartOf="parent"
-			app:layout_constraintTop_toBottomOf="@+id/include_debug_report"
-			tools:visibility="visible"/>
-
-	</android.support.constraint.ConstraintLayout>
-
-	<android.support.constraint.ConstraintLayout
-		android:id="@+id/request_report"
 		android:layout_width="match_parent"
-		android:layout_height="match_parent"
+		android:layout_height="match_parent"/>
-		android:padding="@dimen/margin_large"
-		android:visibility="invisible"
-		tools:visibility="visible">
 
-		<TextView
+</LinearLayout>
-			android:id="@+id/crashed"
-			android:layout_width="match_parent"
-			android:layout_height="wrap_content"
-			android:gravity="center"
-			android:text="@string/briar_crashed"
-			android:textColor="?android:attr/textColorSecondary"
-			android:textSize="@dimen/text_size_large"
-			app:layout_constraintBottom_toTopOf="@+id/fault"
-			app:layout_constraintEnd_toEndOf="parent"
-			app:layout_constraintStart_toStartOf="parent"
-			app:layout_constraintTop_toTopOf="parent"
-			app:layout_constraintVertical_chainStyle="packed"
-			tools:layout_editor_absoluteY="8dp"/>
-
-		<TextView
-			android:id="@+id/fault"
-			android:layout_width="match_parent"
-			android:layout_height="wrap_content"
-			android:layout_marginTop="@dimen/margin_large"
-			android:gravity="center"
-			android:text="@string/not_your_fault"
-			android:textColor="?android:attr/textColorSecondary"
-			android:textSize="@dimen/text_size_large"
-			app:layout_constraintBottom_toTopOf="@+id/pleaseSend"
-			app:layout_constraintEnd_toEndOf="parent"
-			app:layout_constraintStart_toStartOf="parent"
-			app:layout_constraintTop_toBottomOf="@+id/crashed"/>
-
-		<TextView
-			android:id="@+id/pleaseSend"
-			android:layout_width="match_parent"
-			android:layout_height="wrap_content"
-			android:layout_marginTop="@dimen/margin_large"
-			android:gravity="center"
-			android:text="@string/please_send_report"
-			android:textColor="?android:attr/textColorSecondary"
-			android:textSize="@dimen/text_size_large"
-			app:layout_constraintBottom_toTopOf="@+id/encrypted"
-			app:layout_constraintEnd_toEndOf="parent"
-			app:layout_constraintStart_toStartOf="parent"
-			app:layout_constraintTop_toBottomOf="@+id/fault"/>
-
-		<TextView
-			android:id="@+id/encrypted"
-			android:layout_width="match_parent"
-			android:layout_height="wrap_content"
-			android:layout_marginTop="@dimen/margin_large"
-			android:gravity="center"
-			android:text="@string/report_is_encrypted"
-			android:textColor="?android:attr/textColorSecondary"
-			android:textSize="@dimen/text_size_large"
-			app:layout_constraintBottom_toTopOf="@+id/acceptButton"
-			app:layout_constraintEnd_toEndOf="parent"
-			app:layout_constraintStart_toStartOf="parent"
-			app:layout_constraintTop_toBottomOf="@+id/pleaseSend"/>
-
-		<Button
-			android:id="@+id/declineButton"
-			style="@style/BriarButtonFlat.Negative"
-			android:layout_width="0dp"
-			android:layout_height="wrap_content"
-			android:text="@string/close"
-			app:layout_constraintBottom_toBottomOf="@+id/acceptButton"
-			app:layout_constraintEnd_toStartOf="@+id/acceptButton"
-			app:layout_constraintHorizontal_weight="1"
-			app:layout_constraintStart_toStartOf="parent"
-			app:layout_constraintTop_toTopOf="@+id/acceptButton"/>
-
-		<Button
-			android:id="@+id/acceptButton"
-			style="@style/BriarButtonFlat.Positive"
-			android:layout_width="0dp"
-			android:layout_height="wrap_content"
-			android:layout_marginTop="@dimen/margin_large"
-			android:text="@string/send_report"
-			app:layout_constraintBottom_toBottomOf="parent"
-			app:layout_constraintEnd_toEndOf="parent"
-			app:layout_constraintHorizontal_weight="1"
-			app:layout_constraintStart_toEndOf="@+id/declineButton"
-			app:layout_constraintTop_toBottomOf="@+id/encrypted"/>
-
-	</android.support.constraint.ConstraintLayout>
-
-</FrameLayout>

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

@@ -0,0 +1,123 @@
+<?xml version="1.0" encoding="utf-8"?>
+<android.support.constraint.ConstraintLayout
+	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">
+
+	<ScrollView
+		android:id="@+id/scrollView"
+		android:layout_width="match_parent"
+		android:layout_height="0dp"
+		android:fillViewport="true"
+		app:layout_constraintBottom_toTopOf="@+id/acceptButton"
+		app:layout_constraintStart_toStartOf="parent"
+		app:layout_constraintTop_toTopOf="parent">
+
+		<android.support.constraint.ConstraintLayout
+			android:layout_width="match_parent"
+			android:layout_height="wrap_content"
+			android:padding="@dimen/margin_large">
+
+			<android.support.v7.widget.AppCompatImageView
+				android:id="@+id/errorIcon"
+				android:layout_width="0dp"
+				android:layout_height="0dp"
+				android:padding="8dp"
+				android:src="@drawable/ic_crash"
+				app:layout_constraintBottom_toTopOf="@+id/crashed"
+				app:layout_constraintDimensionRatio="1:1"
+				app:layout_constraintEnd_toEndOf="parent"
+				app:layout_constraintHeight_max="128dp"
+				app:layout_constraintStart_toStartOf="parent"
+				app:layout_constraintTop_toTopOf="parent"
+				app:layout_constraintVertical_chainStyle="packed"
+				app:tint="?attr/colorControlNormal"
+				tools:ignore="ContentDescription"/>
+
+			<TextView
+				android:id="@+id/crashed"
+				android:layout_width="match_parent"
+				android:layout_height="wrap_content"
+				android:gravity="center"
+				android:text="@string/briar_crashed"
+				android:textColor="?android:attr/textColorSecondary"
+				android:textSize="@dimen/text_size_large"
+				app:layout_constraintBottom_toTopOf="@+id/fault"
+				app:layout_constraintEnd_toEndOf="parent"
+				app:layout_constraintStart_toStartOf="parent"
+				app:layout_constraintTop_toBottomOf="@+id/errorIcon"
+				tools:layout_editor_absoluteY="8dp"/>
+
+			<TextView
+				android:id="@+id/fault"
+				android:layout_width="match_parent"
+				android:layout_height="wrap_content"
+				android:layout_marginTop="@dimen/margin_large"
+				android:gravity="center"
+				android:text="@string/not_your_fault"
+				android:textColor="?android:attr/textColorSecondary"
+				android:textSize="@dimen/text_size_large"
+				app:layout_constraintBottom_toTopOf="@+id/pleaseSend"
+				app:layout_constraintEnd_toEndOf="parent"
+				app:layout_constraintStart_toStartOf="parent"
+				app:layout_constraintTop_toBottomOf="@+id/crashed"/>
+
+			<TextView
+				android:id="@+id/pleaseSend"
+				android:layout_width="match_parent"
+				android:layout_height="wrap_content"
+				android:layout_marginTop="@dimen/margin_large"
+				android:gravity="center"
+				android:text="@string/please_send_report"
+				android:textColor="?android:attr/textColorSecondary"
+				android:textSize="@dimen/text_size_large"
+				app:layout_constraintBottom_toTopOf="@+id/encrypted"
+				app:layout_constraintEnd_toEndOf="parent"
+				app:layout_constraintStart_toStartOf="parent"
+				app:layout_constraintTop_toBottomOf="@+id/fault"/>
+
+			<TextView
+				android:id="@+id/encrypted"
+				android:layout_width="match_parent"
+				android:layout_height="wrap_content"
+				android:layout_marginTop="@dimen/margin_large"
+				android:gravity="center"
+				android:text="@string/report_is_encrypted"
+				android:textColor="?android:attr/textColorSecondary"
+				android:textSize="@dimen/text_size_large"
+				app:layout_constraintBottom_toBottomOf="parent"
+				app:layout_constraintEnd_toEndOf="parent"
+				app:layout_constraintStart_toStartOf="parent"
+				app:layout_constraintTop_toBottomOf="@+id/pleaseSend"/>
+
+		</android.support.constraint.ConstraintLayout>
+
+	</ScrollView>
+
+	<Button
+		android:id="@+id/declineButton"
+		style="@style/BriarButtonFlat.Negative"
+		android:layout_width="0dp"
+		android:layout_height="wrap_content"
+		android:text="@string/close"
+		app:layout_constraintBottom_toBottomOf="@+id/acceptButton"
+		app:layout_constraintEnd_toStartOf="@+id/acceptButton"
+		app:layout_constraintHorizontal_weight="1"
+		app:layout_constraintStart_toStartOf="parent"
+		app:layout_constraintTop_toTopOf="@+id/acceptButton"/>
+
+	<Button
+		android:id="@+id/acceptButton"
+		style="@style/BriarButtonFlat.Positive"
+		android:layout_width="0dp"
+		android:layout_height="wrap_content"
+		android:text="@string/send_report"
+		app:layout_constraintBottom_toBottomOf="parent"
+		app:layout_constraintEnd_toEndOf="parent"
+		app:layout_constraintHorizontal_weight="1"
+		app:layout_constraintStart_toEndOf="@+id/declineButton"
+		app:layout_constraintTop_toBottomOf="@+id/scrollView"/>
+
+</android.support.constraint.ConstraintLayout>

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

@@ -0,0 +1,113 @@
+<?xml version="1.0" encoding="utf-8"?>
+<ScrollView
+	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"
+	android:fillViewport="true">
+
+	<android.support.constraint.ConstraintLayout
+		android:layout_width="match_parent"
+		android:layout_height="wrap_content">
+
+		<android.support.design.widget.TextInputLayout
+			android:id="@+id/user_comment_layout"
+			android:layout_width="0dp"
+			android:layout_height="wrap_content"
+			android:layout_marginEnd="@dimen/margin_large"
+			android:layout_marginLeft="@dimen/margin_large"
+			android:layout_marginRight="@dimen/margin_large"
+			android:layout_marginStart="@dimen/margin_large"
+			android:layout_marginTop="@dimen/margin_large"
+			app:hintEnabled="false"
+			app:layout_constraintEnd_toEndOf="parent"
+			app:layout_constraintStart_toStartOf="parent"
+			app:layout_constraintTop_toTopOf="parent">
+
+			<android.support.design.widget.TextInputEditText
+				android:id="@+id/user_comment"
+				android:layout_width="match_parent"
+				android:layout_height="wrap_content"
+				android:inputType="textMultiLine|textCapSentences"
+				android:maxLines="5"
+				tools:hint="@string/describe_crash"/>
+
+		</android.support.design.widget.TextInputLayout>
+
+		<android.support.design.widget.TextInputLayout
+			android:id="@+id/user_email_layout"
+			android:layout_width="0dp"
+			android:layout_height="wrap_content"
+			android:layout_marginEnd="@dimen/margin_large"
+			android:layout_marginLeft="@dimen/margin_large"
+			android:layout_marginRight="@dimen/margin_large"
+			android:layout_marginStart="@dimen/margin_large"
+			app:hintEnabled="false"
+			app:layout_constraintEnd_toEndOf="parent"
+			app:layout_constraintStart_toStartOf="parent"
+			app:layout_constraintTop_toBottomOf="@+id/user_comment_layout">
+
+			<android.support.design.widget.TextInputEditText
+				android:id="@+id/user_email"
+				android:layout_width="match_parent"
+				android:layout_height="wrap_content"
+				android:hint="@string/optional_contact_email"
+				android:inputType="textEmailAddress"
+				android:maxLines="1"/>
+
+		</android.support.design.widget.TextInputLayout>
+
+		<CheckBox
+			android:id="@+id/include_debug_report"
+			android:layout_width="0dp"
+			android:layout_height="wrap_content"
+			android:layout_marginLeft="@dimen/margin_large"
+			android:layout_marginStart="@dimen/margin_large"
+			android:checked="false"
+			android:text="@string/include_debug_report_crash"
+			app:layout_constraintBottom_toBottomOf="@+id/chevron"
+			app:layout_constraintEnd_toStartOf="@+id/chevron"
+			app:layout_constraintStart_toStartOf="parent"
+			app:layout_constraintTop_toTopOf="@+id/chevron"/>
+
+		<Button
+			android:id="@+id/chevron"
+			style="@style/BriarButtonFlat.Positive"
+			android:layout_width="wrap_content"
+			android:layout_height="wrap_content"
+			android:text="@string/show"
+			app:layout_constraintEnd_toEndOf="parent"
+			app:layout_constraintTop_toBottomOf="@+id/user_email_layout"/>
+
+		<LinearLayout
+			android:id="@+id/report_content"
+			android:layout_width="match_parent"
+			android:layout_height="wrap_content"
+			android:gravity="center_horizontal"
+			android:orientation="vertical"
+			android:paddingBottom="@dimen/listitem_height_one_line_avatar"
+			android:paddingEnd="@dimen/margin_large"
+			android:paddingStart="@dimen/margin_large"
+			android:paddingTop="@dimen/margin_small"
+			android:visibility="gone"
+			app:layout_constraintStart_toStartOf="parent"
+			app:layout_constraintTop_toBottomOf="@id/include_debug_report"
+			tools:visibility="visible"/>
+
+		<ProgressBar
+			android:id="@+id/progress_wheel"
+			style="?android:attr/progressBarStyleLarge"
+			android:layout_width="wrap_content"
+			android:layout_height="wrap_content"
+			android:indeterminate="true"
+			android:visibility="gone"
+			app:layout_constraintBottom_toBottomOf="parent"
+			app:layout_constraintEnd_toEndOf="parent"
+			app:layout_constraintStart_toStartOf="parent"
+			app:layout_constraintTop_toBottomOf="@+id/include_debug_report"
+			tools:visibility="visible"/>
+
+	</android.support.constraint.ConstraintLayout>
+
+</ScrollView>

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

@@ -129,7 +129,9 @@
 	<string name="message_hint">Type message</string>
 	<string name="image_caption_hint">Add a caption (optional)</string>
 	<string name="image_attach">Attach image</string>
-	<string name="image_attach_error">Could not attach image</string>
+	<string name="image_attach_error">Could not attach image(s)</string>
+	<string name="image_attach_error_too_big">Image too big. Limit is %d MB.</string>
+	<string name="image_attach_error_invalid_mime_type">Image format unsupported: %s</string>
 	<string name="set_contact_alias">Change contact name</string>
 	<string name="set_contact_alias_hint">Contact name</string>
 	<string name="set_alias_button">Change</string>
@@ -148,6 +150,7 @@
 	<string name="dialog_message_no_image_support">Your contact\'s Briar does not yet support image attachments. Once they upgrade you\'ll see a different icon.</string>
 	<string name="dialog_title_image_support">You can now send images to this contact</string>
 	<string name="dialog_message_image_support">Tap this icon to attach images.</string>
+	<string name="messaging_too_many_attachments_toast">Only the first %d images will be sent</string>
 
 	<!-- Adding Contacts -->
 
@@ -213,6 +216,24 @@
 		<item quantity="one">New contact added.</item>
 		<item quantity="other">%d new contacts added.</item>
 	</plurals>
+	<string name="adding_contact_slow_warning">Adding this contact is taking longer than usual</string>
+	<string name="adding_contact_slow_title">Cannot Connect to Contact</string>
+	<string name="adding_contact_slow_text">Adding this contact is taking longer than usual.\n\nPlease check that your contact has received your link and added you:</string>
+	<string name="offline_state">No Internet connection</string>
+	<string name="duplicate_link_dialog_title">Duplicate Link</string>
+	<string name="duplicate_link_dialog_text_1">You already have a pending contact with this link: %s</string>
+	<!-- This is a question asking whether two nicknames refer to the same person -->
+	<string name="duplicate_link_dialog_text_2">Are %s and %s the same person?</string>
+	<!-- This is a button for answering that two nicknames do indeed refer to the same person. This
+	string will be used in a dialog button, so if the translation of this string is longer than 20
+	characters, please use "Yes" instead, and use "No" for the "Different Person" button -->
+	<string name="same_person_button">Same Person</string>
+	<!-- This is a button for answering that two nicknames refer to different people. This string
+	will be used in a dialog button, so if the translation of this string longer than 20 characters,
+	please use "No" instead, and use "Yes" for the "Same Person" button -->
+	<string name="different_person_button">Different Person</string>
+	<string name="duplicate_link_dialog_text_3">%s and %s sent you the same link.\n\nOne of them may be trying to discover who your contacts are.\n\nDon\'t tell them you received the same link from someone else.</string>
+	<string name="pending_contact_updated_toast">Pending contact updated</string>
 
 	<!-- Introductions -->
 

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

@@ -1,8 +1,8 @@
-package org.briarproject.briar.android.conversation;
+package org.briarproject.briar.android.attachment;
 
 import org.briarproject.bramble.api.sync.MessageId;
 import org.briarproject.bramble.test.BrambleMockTestCase;
-import org.briarproject.briar.android.conversation.ImageHelper.DecodeResult;
+import org.briarproject.briar.android.attachment.ImageHelper.DecodeResult;
 import org.briarproject.briar.api.messaging.Attachment;
 import org.briarproject.briar.api.messaging.AttachmentHeader;
 import org.briarproject.briar.api.messaging.MessagingManager;
@@ -19,7 +19,7 @@ import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
 
-public class AttachmentControllerTest extends BrambleMockTestCase {
+public class AttachmentRetrieverTest extends BrambleMockTestCase {
 
 	private final AttachmentDimensions dimensions = new AttachmentDimensions(
 			100, 50, 200, 75, 300
@@ -32,8 +32,8 @@ public class AttachmentControllerTest extends BrambleMockTestCase {
 	private final MessagingManager messagingManager =
 			context.mock(MessagingManager.class);
 	private final ImageHelper imageHelper = context.mock(ImageHelper.class);
-	private final AttachmentController controller =
+	private final AttachmentRetriever controller =
-			new AttachmentController(
+			new AttachmentRetriever(
 					messagingManager,
 					dimensions,
 					imageHelper
@@ -94,23 +94,6 @@ public class AttachmentControllerTest extends BrambleMockTestCase {
 		assertFalse(item.hasError());
 	}
 
-	@Test
-	public void testImageHealsWrongMimeType() {
-		AttachmentHeader h = getAttachmentHeader("image/png");
-
-		context.checking(new Expectations() {{
-			oneOf(imageHelper).decodeStream(with(any(InputStream.class)));
-			will(returnValue(new DecodeResult(160, 240, "image/jpeg")));
-			oneOf(imageHelper).getExtensionFromMimeType("image/jpeg");
-			will(returnValue("jpg"));
-		}});
-
-		AttachmentItem item = controller.getAttachmentItem(h, attachment, true);
-		assertEquals("image/jpeg", item.getMimeType());
-		assertEquals("jpg", item.getExtension());
-		assertFalse(item.hasError());
-	}
-
 	@Test
 	public void testBigJpegImage() {
 		String mimeType = "image/jpeg";

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

@@ -1,4 +1,4 @@
-package org.briarproject.briar.android.conversation;
+package org.briarproject.briar.android.attachment;
 
 import com.bumptech.glide.util.MarkEnforcingInputStream;
 

briar-api/src/main/java/org/briarproject/briar/api/client/ThreadedMessage.java

@@ -4,26 +4,30 @@ import org.briarproject.bramble.api.identity.Author;
 import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import org.briarproject.bramble.api.sync.Message;
 import org.briarproject.bramble.api.sync.MessageId;
-import org.briarproject.briar.api.messaging.PrivateMessage;
 
 import javax.annotation.Nullable;
 import javax.annotation.concurrent.Immutable;
 
 @Immutable
 @NotNullByDefault
-public abstract class ThreadedMessage extends PrivateMessage {
+public abstract class ThreadedMessage {
 
+	private final Message message;
 	@Nullable
 	private final MessageId parent;
 	private final Author author;
 
 	public ThreadedMessage(Message message, @Nullable MessageId parent,
 			Author author) {
-		super(message);
+		this.message = message;
 		this.parent = parent;
 		this.author = author;
 	}
 
+	public Message getMessage() {
+		return message;
+	}
+
 	@Nullable
 	public MessageId getParent() {
 		return parent;