Bump client minor version to avoid triggering crash.

Compress images

See merge request briar/briar!1147

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(
-					"Shared undelivered message");
+			throw new IllegalArgumentException("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
-	private boolean closed = false; // Locking: connectionsLock
+	@GuardedBy("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)"
-					+ " VALUES (?, ?, ?, ?, ?, ?, ?)";
+					+ " state, shared, temporary, length, raw)"
+					+ " 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.setBytes(7, raw);
+			ps.setInt(7, raw.length);
+			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,
-						false, seen);
+						raw.length, state, e.getValue(), shared, 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) {
-			broadcastState(p.getId(), WAITING_FOR_CONNECTION);
-		} else {
+		if (expiry <= now) {
 			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 =
-					createEndpoint(plugin, e.getKey(), e.getValue());
-			if (endpoint != null) endpoints.put(e.getKey(), endpoint);
+			PendingContactId p = e.getKey();
+			CryptoState cs = e.getValue();
+			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()) {
-				tryToClose(endpoint, LOG, INFO);
+			for (Entry<PendingContactId, RendezvousEndpoint> e :
+					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)
-					.broadcast(with(any(MessageStateChangedEvent.class)));
-			oneOf(eventBus).broadcast(with(any(MessageSharedEvent.class)));
+			oneOf(eventBus).broadcast(with(any(
+					MessageStateChangedEvent.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, message1, DELIVERED, true, contactId);
+		db.addMessage(txn, message, DELIVERED, true, false, 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, message1, DELIVERED, true, null);
+		db.addMessage(txn, message, DELIVERED, true, false, 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, message1, DELIVERED, true, null);
+		db.addMessage(txn, message, DELIVERED, true, false, 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, message1, PENDING, true, contactId);
-		db.addMessage(txn, message2, INVALID, true, contactId);
+		db.addMessage(txn, message, PENDING, true, false, contactId);
+		db.addMessage(txn, message1, PENDING, true, false, 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, message2, INVALID, true, contactId);
-		db.addMessage(txn, message3, PENDING, true, contactId);
-		db.addMessage(txn, message4, DELIVERED, true, contactId);
+		db.addMessage(txn, message1, UNKNOWN, true, false, contactId);
+		db.addMessage(txn, message2, INVALID, true, false, contactId);
+		db.addMessage(txn, message3, PENDING, true, false, 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, message2, DELIVERED, false, contactId);
-		db.addMessage(txn, message3, DELIVERED, false, contactId);
-		db.addMessage(txn, message4, DELIVERED, true, contactId);
+		db.addMessage(txn, message1, DELIVERED, true, false, contactId);
+		db.addMessage(txn, message2, DELIVERED, false, false, contactId);
+		db.addMessage(txn, message3, DELIVERED, false, false, 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() {{
-			oneOf(rendezvousEndpoint).close();
-		}});
+		expectCloseEndpoint();
 
 		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);
-
-		context.checking(new Expectations() {{
-			oneOf(rendezvousEndpoint).close();
-		}});
+		expectCloseEndpoint();
 
 		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() {{
-			oneOf(rendezvousEndpoint).close();
-		}});
+		expectCloseEndpoint();
+		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);
-		Transaction txn1 = new Transaction(null, true);
-		Transaction txn2 = new Transaction(null, true);
-
-		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()));
-		}});
+		expectGetMessagesToValidate();
+		expectGetPendingMessages();
+		expectGetMessagesToShare();
 
 		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 txn2 = new Transaction(null, false);
-		Transaction txn3 = new Transaction(null, true);
-		Transaction txn4 = new Transaction(null, false);
-		Transaction txn5 = new Transaction(null, true);
-		Transaction txn6 = new Transaction(null, true);
+		Transaction txn1 = new Transaction(null, false);
+		Transaction txn2 = new Transaction(null, true);
+		Transaction txn3 = new Transaction(null, false);
+
+		expectGetMessagesToValidate(messageId, messageId1);
 
 		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).getMessage(txn1, messageId);
+			oneOf(db).transactionWithResult(with(true), withDbCallable(txn));
+			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).mergeMessageMetadata(txn2, messageId, metadata);
+			oneOf(db).transaction(with(false), withDbRunnable(txn1));
+			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).getMessage(txn3, messageId1);
+			oneOf(db).transactionWithResult(with(true), withDbCallable(txn2));
+			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).getMessageState(txn4, messageId1);
+			oneOf(db).transaction(with(false), withDbRunnable(txn3));
+			oneOf(db).getMessageState(txn3, messageId1);
 			will(returnValue(UNKNOWN));
-			oneOf(db).setMessageState(txn4, messageId1, INVALID);
-			oneOf(db).deleteMessage(txn4, messageId1);
-			oneOf(db).deleteMessageMetadata(txn4, messageId1);
+			oneOf(db).setMessageState(txn3, messageId1, INVALID);
+			oneOf(db).deleteMessage(txn3, 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 txn1 = new Transaction(null, true);
-		Transaction txn2 = new Transaction(null, false);
-		Transaction txn3 = new Transaction(null, false);
-		Transaction txn4 = new Transaction(null, true);
+		Transaction txn = new Transaction(null, false);
+		Transaction txn1 = new Transaction(null, false);
+
+		expectGetMessagesToValidate();
+		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).getMessageState(txn2, messageId);
+			oneOf(db).transaction(with(false), withDbRunnable(txn));
+			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).getMessageState(txn3, messageId2);
+			oneOf(db).transaction(with(false), withDbRunnable(txn1));
+			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 txn1 = new Transaction(null, true);
-		Transaction txn2 = new Transaction(null, true);
-		Transaction txn3 = new Transaction(null, false);
-		Transaction txn4 = new Transaction(null, false);
+		Transaction txn = new Transaction(null, false);
+		Transaction txn1 = new Transaction(null, false);
+
+		expectGetMessagesToValidate();
+		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).setMessageShared(txn3, messageId);
-			oneOf(db).getMessageDependencies(txn3, messageId);
+			oneOf(db).transaction(with(false), withDbRunnable(txn));
+			oneOf(db).setMessageShared(txn, messageId);
+			oneOf(db).getMessageDependencies(txn, messageId);
 			will(returnValue(singletonMap(messageId2, DELIVERED)));
 			// Share dependency
-			oneOf(db).transaction(with(false), withDbRunnable(txn4));
-			oneOf(db).setMessageShared(txn4, messageId2);
-			oneOf(db).getMessageDependencies(txn4, messageId2);
+			oneOf(db).transaction(with(false), withDbRunnable(txn1));
+			oneOf(db).setMessageShared(txn1, 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 txn3 = new Transaction(null, false);
-		Transaction txn4 = new Transaction(null, true);
-		Transaction txn5 = new Transaction(null, true);
+		Transaction txn2 = new Transaction(null, false);
+
+		expectGetMessagesToValidate(messageId, messageId1);
 
 		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).getMessage(txn1, messageId);
+			oneOf(db).transactionWithResult(with(true), withDbCallable(txn));
+			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).getMessage(txn2, messageId1);
+			oneOf(db).transactionWithResult(with(true), withDbCallable(txn1));
+			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).getMessageState(txn3, messageId1);
+			oneOf(db).transaction(with(false), withDbRunnable(txn2));
+			oneOf(db).getMessageState(txn2, messageId1);
 			will(returnValue(UNKNOWN));
-			oneOf(db).setMessageState(txn3, messageId1, INVALID);
-			oneOf(db).deleteMessage(txn3, messageId1);
-			oneOf(db).deleteMessageMetadata(txn3, messageId1);
+			oneOf(db).setMessageState(txn2, messageId1, INVALID);
+			oneOf(db).deleteMessage(txn2, 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 txn3 = new Transaction(null, false);
-		Transaction txn4 = new Transaction(null, true);
-		Transaction txn5 = new Transaction(null, true);
+		Transaction txn2 = new Transaction(null, false);
+
+		expectGetMessagesToValidate(messageId, messageId1);
 
 		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).getMessage(txn1, messageId);
+			oneOf(db).transactionWithResult(with(true), withDbCallable(txn));
+			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).getMessage(txn2, messageId1);
+			oneOf(db).transactionWithResult(with(true), withDbCallable(txn1));
+			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).getMessageState(txn3, messageId1);
+			oneOf(db).transaction(with(false), withDbRunnable(txn2));
+			oneOf(db).getMessageState(txn2, messageId1);
 			will(returnValue(UNKNOWN));
-			oneOf(db).setMessageState(txn3, messageId1, INVALID);
-			oneOf(db).deleteMessage(txn3, messageId1);
-			oneOf(db).deleteMessageMetadata(txn3, messageId1);
+			oneOf(db).setMessageState(txn2, messageId1, INVALID);
+			oneOf(db).deleteMessage(txn2, 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/proguard-rules.txt

@@ -5,6 +5,10 @@
 
 # QR codes
 -keep class com.google.zxing.Result
+-keepclassmembers enum * {
+    public static **[] values();
+    public static ** valueOf(java.lang.String);
+}
 
 # RSS libraries
 -keep,includedescriptorclasses class com.rometools.rome.feed.synd.impl.** { *; }

briar-android/src/androidTestOfficial/java/org/briarproject/briar/android/BriarUiTestComponent.java

@@ -4,6 +4,7 @@ import org.briarproject.bramble.BrambleAndroidModule;
 import org.briarproject.bramble.BrambleCoreModule;
 import org.briarproject.bramble.account.BriarAccountModule;
 import org.briarproject.briar.BriarCoreModule;
+import org.briarproject.briar.android.attachment.AttachmentModule;
 import org.briarproject.briar.android.navdrawer.NavDrawerActivityTest;
 
 import javax.inject.Singleton;
@@ -13,6 +14,7 @@ import dagger.Component;
 @Singleton
 @Component(modules = {
 		AppModule.class,
+		AttachmentModule.class,
 		BriarCoreModule.class,
 		BrambleAndroidModule.class,
 		BriarAccountModule.class,

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 +47,17 @@ public class AttachmentControllerIntegrationTest {
 	);
 	private final MessageId msgId = new MessageId(getRandomId());
 
-	private final AttachmentController controller =
-			new AttachmentController(null, dimensions);
+	private final ImageHelper imageHelper = new ImageHelperImpl();
+	private final AttachmentRetriever retriever =
+			new AttachmentRetrieverImpl(null, dimensions, imageHelper,
+					new ImageSizeCalculator(imageHelper));
 
 	@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);
+		Attachment a = new Attachment(h, is);
+		AttachmentItem item = retriever.getAttachmentItem(a, true);
 		assertEquals(msgId, item.getMessageId());
 		assertEquals(160, item.getWidth());
 		assertEquals(240, item.getHeight());
@@ -70,8 +72,8 @@ public class AttachmentControllerIntegrationTest {
 	public void testBigJpegImage() throws Exception {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/jpeg");
 		InputStream is = getUrlInputStream(originalKitten);
-		Attachment a = new Attachment(is);
-		AttachmentItem item = controller.getAttachmentItem(h, a, true);
+		Attachment a = new Attachment(h, is);
+		AttachmentItem item = retriever.getAttachmentItem(a, true);
 		assertEquals(msgId, item.getMessageId());
 		assertEquals(1728, item.getWidth());
 		assertEquals(2592, item.getHeight());
@@ -86,8 +88,8 @@ public class AttachmentControllerIntegrationTest {
 	public void testSmallPngImage() throws Exception {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/png");
 		InputStream is = getUrlInputStream(pngKitten);
-		Attachment a = new Attachment(is);
-		AttachmentItem item = controller.getAttachmentItem(h, a, true);
+		Attachment a = new Attachment(h, is);
+		AttachmentItem item = retriever.getAttachmentItem(a, true);
 		assertEquals(msgId, item.getMessageId());
 		assertEquals(737, item.getWidth());
 		assertEquals(510, item.getHeight());
@@ -102,8 +104,8 @@ public class AttachmentControllerIntegrationTest {
 	public void testUberGif() throws Exception {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/jpeg");
 		InputStream is = getUrlInputStream(uberGif);
-		Attachment a = new Attachment(is);
-		AttachmentItem item = controller.getAttachmentItem(h, a, true);
+		Attachment a = new Attachment(h, is);
+		AttachmentItem item = retriever.getAttachmentItem(a, true);
 		assertEquals(1, item.getWidth());
 		assertEquals(1, item.getHeight());
 		assertEquals(dimensions.minHeight, item.getThumbnailWidth());
@@ -117,8 +119,8 @@ public class AttachmentControllerIntegrationTest {
 	public void testLottaPixels() throws Exception {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/jpeg");
 		InputStream is = getUrlInputStream(lottaPixel);
-		Attachment a = new Attachment(is);
-		AttachmentItem item = controller.getAttachmentItem(h, a, true);
+		Attachment a = new Attachment(h, is);
+		AttachmentItem item = retriever.getAttachmentItem(a, true);
 		assertEquals(64250, item.getWidth());
 		assertEquals(64250, item.getHeight());
 		assertEquals(dimensions.maxWidth, item.getThumbnailWidth());
@@ -132,8 +134,8 @@ public class AttachmentControllerIntegrationTest {
 	public void testImageIoCrash() throws Exception {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/jpeg");
 		InputStream is = getUrlInputStream(imageIoCrash);
-		Attachment a = new Attachment(is);
-		AttachmentItem item = controller.getAttachmentItem(h, a, true);
+		Attachment a = new Attachment(h, is);
+		AttachmentItem item = retriever.getAttachmentItem(a, true);
 		assertEquals(1184, item.getWidth());
 		assertEquals(448, item.getHeight());
 		assertEquals(dimensions.maxWidth, item.getThumbnailWidth());
@@ -147,8 +149,8 @@ public class AttachmentControllerIntegrationTest {
 	public void testGimpCrash() throws Exception {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/jpeg");
 		InputStream is = getUrlInputStream(gimpCrash);
-		Attachment a = new Attachment(is);
-		AttachmentItem item = controller.getAttachmentItem(h, a, true);
+		Attachment a = new Attachment(h, is);
+		AttachmentItem item = retriever.getAttachmentItem(a, true);
 		assertEquals(1, item.getWidth());
 		assertEquals(1, item.getHeight());
 		assertEquals(dimensions.minHeight, item.getThumbnailWidth());
@@ -162,8 +164,8 @@ public class AttachmentControllerIntegrationTest {
 	public void testOptiPngAfl() throws Exception {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/jpeg");
 		InputStream is = getUrlInputStream(optiPngAfl);
-		Attachment a = new Attachment(is);
-		AttachmentItem item = controller.getAttachmentItem(h, a, true);
+		Attachment a = new Attachment(h, is);
+		AttachmentItem item = retriever.getAttachmentItem(a, true);
 		assertEquals(32, item.getWidth());
 		assertEquals(32, item.getHeight());
 		assertEquals(dimensions.minHeight, item.getThumbnailWidth());
@@ -177,8 +179,8 @@ public class AttachmentControllerIntegrationTest {
 	public void testLibrawError() throws Exception {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/jpeg");
 		InputStream is = getUrlInputStream(librawError);
-		Attachment a = new Attachment(is);
-		AttachmentItem item = controller.getAttachmentItem(h, a, true);
+		Attachment a = new Attachment(h, is);
+		AttachmentItem item = retriever.getAttachmentItem(a, true);
 		assertTrue(item.hasError());
 	}
 
@@ -186,8 +188,8 @@ public class AttachmentControllerIntegrationTest {
 	public void testSmallAnimatedGifMaxDimensions() throws Exception {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/gif");
 		InputStream is = getAssetInputStream("animated.gif");
-		Attachment a = new Attachment(is);
-		AttachmentItem item = controller.getAttachmentItem(h, a, true);
+		Attachment a = new Attachment(h, is);
+		AttachmentItem item = retriever.getAttachmentItem(a, true);
 		assertEquals(65535, item.getWidth());
 		assertEquals(65535, item.getHeight());
 		assertEquals(dimensions.maxWidth, item.getThumbnailWidth());
@@ -201,8 +203,8 @@ public class AttachmentControllerIntegrationTest {
 	public void testSmallAnimatedGifHugeDimensions() throws Exception {
 		AttachmentHeader h = new AttachmentHeader(msgId, "image/gif");
 		InputStream is = getAssetInputStream("animated2.gif");
-		Attachment a = new Attachment(is);
-		AttachmentItem item = controller.getAttachmentItem(h, a, true);
+		Attachment a = new Attachment(h, is);
+		AttachmentItem item = retriever.getAttachmentItem(a, true);
 		assertEquals(10000, item.getWidth());
 		assertEquals(10000, item.getHeight());
 		assertEquals(dimensions.maxWidth, item.getThumbnailWidth());
@@ -216,8 +218,8 @@ public class AttachmentControllerIntegrationTest {
 	public void testSmallGifLargeDimensions() throws Exception {
 		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);
+		Attachment a = new Attachment(h, is);
+		AttachmentItem item = retriever.getAttachmentItem(a, true);
 		assertEquals(16384, item.getWidth());
 		assertEquals(16384, item.getHeight());
 		assertEquals(dimensions.maxWidth, item.getThumbnailWidth());
@@ -231,8 +233,8 @@ public class AttachmentControllerIntegrationTest {
 	public void testHighError() throws Exception {
 		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);
+		Attachment a = new Attachment(h, is);
+		AttachmentItem item = retriever.getAttachmentItem(a, true);
 		assertEquals(1, item.getWidth());
 		assertEquals(10000, item.getHeight());
 		assertEquals(dimensions.minWidth, item.getThumbnailWidth());
@@ -246,8 +248,8 @@ public class AttachmentControllerIntegrationTest {
 	public void testWideError() throws Exception {
 		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);
+		Attachment a = new Attachment(h, is);
+		AttachmentItem item = retriever.getAttachmentItem(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;
@@ -29,6 +30,7 @@ import org.briarproject.bramble.api.system.LocationUtils;
 import org.briarproject.bramble.plugin.tor.CircumventionProvider;
 import org.briarproject.briar.BriarCoreEagerSingletons;
 import org.briarproject.briar.BriarCoreModule;
+import org.briarproject.briar.android.attachment.AttachmentModule;
 import org.briarproject.briar.android.conversation.glide.BriarModelLoader;
 import org.briarproject.briar.android.login.SignInReminderReceiver;
 import org.briarproject.briar.android.reporting.BriarReportSender;
@@ -67,7 +69,8 @@ import dagger.Component;
 		BriarCoreModule.class,
 		BrambleAndroidModule.class,
 		BriarAccountModule.class,
-		AppModule.class
+		AppModule.class,
+		AttachmentModule.class
 })
 public interface AndroidComponent
 		extends BrambleCoreEagerSingletons, BrambleAndroidEagerSingletons,
@@ -161,6 +164,8 @@ 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 = false;
-
-	/**
-	 * 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/account/AuthorNameFragment.java

@@ -3,6 +3,7 @@ package org.briarproject.briar.android.account;
 import android.os.Bundle;
 import android.support.design.widget.TextInputEditText;
 import android.support.design.widget.TextInputLayout;
+import android.text.Editable;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
@@ -10,7 +11,6 @@ import android.widget.Button;
 
 import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
 import org.briarproject.bramble.api.nullsafety.ParametersNotNullByDefault;
-import org.briarproject.bramble.util.StringUtils;
 import org.briarproject.briar.R;
 import org.briarproject.briar.android.activity.ActivityComponent;
 
@@ -20,6 +20,7 @@ import static android.view.inputmethod.EditorInfo.IME_ACTION_NEXT;
 import static android.view.inputmethod.EditorInfo.IME_ACTION_NONE;
 import static java.util.Objects.requireNonNull;
 import static org.briarproject.bramble.api.identity.AuthorConstants.MAX_AUTHOR_NAME_LENGTH;
+import static org.briarproject.bramble.util.StringUtils.toUtf8;
 import static org.briarproject.briar.android.util.UiUtils.setError;
 import static org.briarproject.briar.android.util.UiUtils.showSoftKeyboard;
 
@@ -77,7 +78,7 @@ public class AuthorNameFragment extends SetupFragment {
 
 	@Override
 	public void onTextChanged(CharSequence authorName, int i, int i1, int i2) {
-		int authorNameLength = StringUtils.toUtf8(authorName.toString()).length;
+		int authorNameLength = toUtf8(authorName.toString().trim()).length;
 		boolean error = authorNameLength > MAX_AUTHOR_NAME_LENGTH;
 		setError(authorNameWrapper, getString(R.string.name_too_long), error);
 		boolean enabled = authorNameLength > 0 && !error;
@@ -89,8 +90,11 @@ public class AuthorNameFragment extends SetupFragment {
 
 	@Override
 	public void onClick(View view) {
-		setupController.setAuthorName(authorNameInput.getText().toString());
-		setupController.showPasswordFragment();
+		Editable text = authorNameInput.getText();
+		if (text != null) {
+			setupController.setAuthorName(text.toString().trim());
+			setupController.showPasswordFragment();
+		}
 	}
 
 }

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

@@ -0,0 +1,176 @@
+package org.briarproject.briar.android.attachment;
+
+import android.content.ContentResolver;
+import android.graphics.Bitmap;
+import android.graphics.BitmapFactory.Options;
+import android.net.Uri;
+import android.support.annotation.Nullable;
+
+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.AttachmentHeader;
+import org.briarproject.briar.api.messaging.MessagingManager;
+import org.jsoup.UnsupportedMimeTypeException;
+
+import java.io.BufferedInputStream;
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.Collection;
+import java.util.logging.Logger;
+
+import static android.graphics.Bitmap.CompressFormat.JPEG;
+import static android.graphics.BitmapFactory.decodeStream;
+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;
+import static org.briarproject.briar.api.messaging.MessagingConstants.MAX_IMAGE_SIZE;
+
+@NotNullByDefault
+class AttachmentCreationTask {
+
+	private static Logger LOG =
+			getLogger(AttachmentCreationTask.class.getName());
+
+	private static final int MAX_ATTACHMENT_DIMENSION = 1000;
+
+	private final MessagingManager messagingManager;
+	private final ContentResolver contentResolver;
+	private final ImageSizeCalculator imageSizeCalculator;
+	private final GroupId groupId;
+	private final Collection<Uri> uris;
+	private final boolean needsSize;
+	@Nullable
+	private volatile AttachmentCreator attachmentCreator;
+
+	private volatile boolean canceled = false;
+
+	AttachmentCreationTask(MessagingManager messagingManager,
+			ContentResolver contentResolver,
+			AttachmentCreator attachmentCreator,
+			ImageSizeCalculator imageSizeCalculator,
+			GroupId groupId, Collection<Uri> uris, boolean needsSize) {
+		this.messagingManager = messagingManager;
+		this.contentResolver = contentResolver;
+		this.imageSizeCalculator = imageSizeCalculator;
+		this.groupId = groupId;
+		this.uris = uris;
+		this.needsSize = needsSize;
+		this.attachmentCreator = attachmentCreator;
+	}
+
+	void cancel() {
+		canceled = true;
+		attachmentCreator = null;
+	}
+
+	@IoExecutor
+	void storeAttachments() {
+		for (Uri uri : uris) processUri(uri);
+		AttachmentCreator attachmentCreator = this.attachmentCreator;
+		if (!canceled && attachmentCreator != null)
+			attachmentCreator.onAttachmentCreationFinished();
+		this.attachmentCreator = null;
+	}
+
+	@IoExecutor
+	private void processUri(Uri uri) {
+		if (canceled) return;
+		try {
+			AttachmentHeader h = storeAttachment(uri);
+			AttachmentCreator attachmentCreator = this.attachmentCreator;
+			if (attachmentCreator != null) {
+				attachmentCreator.onAttachmentHeaderReceived(uri, h, needsSize);
+			}
+		} catch (DbException | IOException e) {
+			logException(LOG, WARNING, e);
+			AttachmentCreator attachmentCreator = this.attachmentCreator;
+			if (attachmentCreator != null) {
+				attachmentCreator.onAttachmentError(uri, e);
+			}
+			canceled = true;
+		}
+	}
+
+	@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();
+		is = compressImage(is, contentType);
+		contentType = "image/jpeg";
+		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 InputStream compressImage(InputStream is, String contentType)
+			throws IOException {
+		ByteArrayOutputStream out = new ByteArrayOutputStream();
+		try {
+			Bitmap bitmap = createBitmap(is, contentType);
+			for (int quality = 100; quality >= 0; quality -= 10) {
+				if (!bitmap.compress(JPEG, quality, out))
+					throw new IOException();
+				if (out.size() <= MAX_IMAGE_SIZE) {
+					if (LOG.isLoggable(INFO)) {
+						LOG.info("Compressed image to "
+								+ out.size() + " bytes, quality " + quality);
+					}
+					return new ByteArrayInputStream(out.toByteArray());
+				}
+				out.reset();
+			}
+			throw new IOException();
+		} finally {
+			tryToClose(is, LOG, WARNING);
+		}
+	}
+
+	private Bitmap createBitmap(InputStream is, String contentType)
+			throws IOException {
+		is = new BufferedInputStream(is);
+		Size size = imageSizeCalculator.getSize(is, contentType);
+		if (size.error) throw new IOException();
+		if (LOG.isLoggable(INFO))
+			LOG.info("Original image size: " + size.width + "x" + size.height);
+		int dimension = Math.max(size.width, size.height);
+		int inSampleSize = 1;
+		while (dimension > MAX_ATTACHMENT_DIMENSION) {
+			inSampleSize *= 2;
+			dimension /= 2;
+		}
+		if (LOG.isLoggable(INFO))
+			LOG.info("Scaling attachment by factor of " + inSampleSize);
+		Options options = new Options();
+		options.inSampleSize = inSampleSize;
+		Bitmap bitmap = decodeStream(is, null, options);
+		if (bitmap == null) throw new IOException();
+		return bitmap;
+	}
+}

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

@@ -0,0 +1,60 @@
+package org.briarproject.briar.android.attachment;
+
+import android.arch.lifecycle.LiveData;
+import android.net.Uri;
+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.bramble.api.sync.MessageId;
+import org.briarproject.briar.api.messaging.AttachmentHeader;
+
+import java.util.Collection;
+import java.util.List;
+
+@NotNullByDefault
+public interface AttachmentCreator {
+
+	@UiThread
+	LiveData<AttachmentResult> storeAttachments(LiveData<GroupId> groupId,
+			Collection<Uri> newUris);
+
+	/**
+	 * 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
+	LiveData<AttachmentResult> getLiveAttachments();
+
+	@UiThread
+	List<AttachmentHeader> getAttachmentHeadersForSending();
+
+	/**
+	 * Marks the attachments as sent and adds the items to the cache for display
+	 *
+	 * @param id The MessageId of the sent message.
+	 */
+	@UiThread
+	void onAttachmentsSent(MessageId id);
+
+	/**
+	 * Needs to be called when created attachments will not be sent anymore.
+	 */
+	@UiThread
+	void cancel();
+
+	@UiThread
+	void deleteUnsentAttachments();
+
+	@IoExecutor
+	void onAttachmentHeaderReceived(Uri uri, AttachmentHeader h,
+			boolean needsSize);
+
+	@IoExecutor
+	void onAttachmentError(Uri uri, Throwable t);
+
+	@IoExecutor
+	void onAttachmentCreationFinished();
+}

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

@@ -0,0 +1,233 @@
+package org.briarproject.briar.android.attachment;
+
+
+import android.app.Application;
+import android.arch.lifecycle.LiveData;
+import android.arch.lifecycle.MutableLiveData;
+import android.net.Uri;
+import android.support.annotation.Nullable;
+import android.support.annotation.UiThread;
+
+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.bramble.api.sync.MessageId;
+import org.briarproject.briar.R;
+import org.briarproject.briar.api.messaging.Attachment;
+import org.briarproject.briar.api.messaging.AttachmentHeader;
+import org.briarproject.briar.api.messaging.FileTooBigException;
+import org.briarproject.briar.api.messaging.MessagingManager;
+import org.jsoup.UnsupportedMimeTypeException;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.List;
+import java.util.concurrent.CopyOnWriteArrayList;
+import java.util.concurrent.Executor;
+import java.util.logging.Logger;
+
+import javax.inject.Inject;
+
+import static java.util.logging.Level.WARNING;
+import static java.util.logging.Logger.getLogger;
+import static org.briarproject.bramble.util.LogUtils.logException;
+import static org.briarproject.briar.android.util.UiUtils.observeForeverOnce;
+import static org.briarproject.briar.api.messaging.MessagingConstants.MAX_IMAGE_SIZE;
+
+@NotNullByDefault
+class AttachmentCreatorImpl implements AttachmentCreator {
+
+	private static Logger LOG =
+			getLogger(AttachmentCreatorImpl.class.getName());
+
+	private final Application app;
+	@IoExecutor
+	private final Executor ioExecutor;
+	private final MessagingManager messagingManager;
+	private final AttachmentRetriever retriever;
+	private final ImageSizeCalculator imageSizeCalculator;
+
+	private final CopyOnWriteArrayList<Uri> uris = new CopyOnWriteArrayList<>();
+	private final CopyOnWriteArrayList<AttachmentItemResult> itemResults =
+			new CopyOnWriteArrayList<>();
+
+	@Nullable
+	private AttachmentCreationTask task;
+
+	@Nullable
+	private volatile MutableLiveData<AttachmentResult> result;
+
+	@Inject
+	AttachmentCreatorImpl(Application app, @IoExecutor Executor ioExecutor,
+			MessagingManager messagingManager, AttachmentRetriever retriever,
+			ImageSizeCalculator imageSizeCalculator) {
+		this.app = app;
+		this.ioExecutor = ioExecutor;
+		this.messagingManager = messagingManager;
+		this.retriever = retriever;
+		this.imageSizeCalculator = imageSizeCalculator;
+	}
+
+	@Override
+	@UiThread
+	public LiveData<AttachmentResult> storeAttachments(
+			LiveData<GroupId> groupId, Collection<Uri> newUris) {
+		if (task != null || result != null || !uris.isEmpty())
+			throw new IllegalStateException();
+		MutableLiveData<AttachmentResult> result = new MutableLiveData<>();
+		this.result = result;
+		uris.addAll(newUris);
+		observeForeverOnce(groupId, id -> {
+			if (id == null) throw new IllegalStateException();
+			boolean needsSize = uris.size() == 1;
+			task = new AttachmentCreationTask(messagingManager,
+					app.getContentResolver(), this, imageSizeCalculator, id,
+					uris, needsSize);
+			ioExecutor.execute(() -> task.storeAttachments());
+		});
+		return result;
+	}
+
+	@Override
+	@UiThread
+	public LiveData<AttachmentResult> getLiveAttachments() {
+		MutableLiveData<AttachmentResult> result = this.result;
+		if (task == null || result == null || uris.isEmpty())
+			throw new IllegalStateException();
+		// A task is already running. It will update the result LiveData.
+		// So nothing more to do here.
+		return result;
+	}
+
+	@Override
+	@IoExecutor
+	public void onAttachmentHeaderReceived(Uri uri, AttachmentHeader h,
+			boolean needsSize) {
+		// get and cache AttachmentItem for ImagePreview
+		try {
+			Attachment a = retriever.getMessageAttachment(h);
+			AttachmentItem item = retriever.getAttachmentItem(a, needsSize);
+			if (item.hasError()) throw new IOException();
+			AttachmentItemResult itemResult =
+					new AttachmentItemResult(uri, item);
+			itemResults.add(itemResult);
+			MutableLiveData<AttachmentResult> result = this.result;
+			if (result != null) result.postValue(getResult(false));
+		} catch (IOException | DbException e) {
+			logException(LOG, WARNING, e);
+			onAttachmentError(uri, e);
+		}
+	}
+
+	@Override
+	@IoExecutor
+	public void onAttachmentError(Uri uri, Throwable t) {
+		// get error message
+		String errorMsg;
+		if (t instanceof UnsupportedMimeTypeException) {
+			String mimeType = ((UnsupportedMimeTypeException) t).getMimeType();
+			errorMsg = app.getString(
+					R.string.image_attach_error_invalid_mime_type, mimeType);
+		} else if (t instanceof FileTooBigException) {
+			int mb = MAX_IMAGE_SIZE / 1024 / 1024;
+			errorMsg = app.getString(R.string.image_attach_error_too_big, mb);
+		} else {
+			errorMsg = null; // generic error
+		}
+		AttachmentItemResult itemResult =
+				new AttachmentItemResult(uri, errorMsg);
+		itemResults.add(itemResult);
+		MutableLiveData<AttachmentResult> result = this.result;
+		if (result != null) result.postValue(getResult(false));
+		// expect to receive a cancel from the UI
+	}
+
+	@Override
+	@IoExecutor
+	public void onAttachmentCreationFinished() {
+		MutableLiveData<AttachmentResult> result = this.result;
+		if (result != null) result.postValue(getResult(true));
+	}
+
+	@Override
+	@UiThread
+	public List<AttachmentHeader> getAttachmentHeadersForSending() {
+		List<AttachmentHeader> headers = new ArrayList<>(itemResults.size());
+		for (AttachmentItemResult itemResult : itemResults) {
+			// check if we are trying to send attachment items with errors
+			if (itemResult.getItem() == null) throw new IllegalStateException();
+			headers.add(itemResult.getItem().getHeader());
+		}
+		return headers;
+	}
+
+	@Override
+	@UiThread
+	public void onAttachmentsSent(MessageId id) {
+		List<AttachmentItem> items = new ArrayList<>(itemResults.size());
+		for (AttachmentItemResult itemResult : itemResults) {
+			// check if we are trying to send attachment items with errors
+			if (itemResult.getItem() == null) throw new IllegalStateException();
+			items.add(itemResult.getItem());
+		}
+		retriever.cachePut(id, items);
+		resetState();
+	}
+
+	@Override
+	@UiThread
+	public void cancel() {
+		if (task == null) throw new AssertionError();
+		task.cancel();
+		deleteUnsentAttachments();
+		resetState();
+	}
+
+	@UiThread
+	private void resetState() {
+		task = null;
+		uris.clear();
+		itemResults.clear();
+		MutableLiveData<AttachmentResult> result = this.result;
+		if (result != null) {
+			result.setValue(null);
+			this.result = null;
+		}
+	}
+
+	@Override
+	@UiThread
+	public void deleteUnsentAttachments() {
+		// Make a copy for the IoExecutor as we clear the itemResults soon
+		List<AttachmentHeader> headers = new ArrayList<>(itemResults.size());
+		for (AttachmentItemResult itemResult : itemResults) {
+			// check if we are trying to send attachment items with errors
+			if (itemResult.getItem() != null)
+				headers.add(itemResult.getItem().getHeader());
+		}
+		ioExecutor.execute(() -> {
+			for (AttachmentHeader header : headers) {
+				try {
+					messagingManager.removeAttachment(header);
+				} catch (DbException e) {
+					logException(LOG, WARNING, e);
+				}
+			}
+		});
+	}
+
+	private AttachmentResult getResult(boolean finished) {
+		// Make a copy of the list,
+		// because our copy will continue to change in the background.
+		// (As it's a CopyOnWriteArrayList,
+		//  the code that receives the result can safely do simple things
+		//  like iterating over the list,
+		//  but anything that involves calling more than one list method
+		//  is still unsafe.)
+		Collection<AttachmentItemResult> items = new ArrayList<>(itemResults);
+		return new AttachmentResult(items, finished);
+	}
+
+}

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

@@ -1,10 +1,15 @@
-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;
 
+import javax.annotation.concurrent.Immutable;
+
+@Immutable
+@NotNullByDefault
 class AttachmentDimensions {
 
 	final int defaultSize;
@@ -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();
-		extension = in.readString();
+		String mimeType = requireNonNull(in.readString());
+		extension = requireNonNull(in.readString());
 		thumbnailWidth = in.readInt();
 		thumbnailHeight = in.readInt();
 		hasError = in.readByte() != 0;
 		instanceId = in.readLong();
+		header = new AttachmentHeader(messageId, mimeType);
+	}
+
+	public 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() {
-		return mimeType;
+	public String getMimeType() {
+		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 String errorMsg;
+
+	AttachmentItemResult(Uri uri, AttachmentItem item) {
+		this.uri = uri;
+		this.item = item;
+		this.errorMsg = null;
+	}
+
+	AttachmentItemResult(Uri uri, @Nullable String errorMsg) {
+		this.uri = uri;
+		this.item = null;
+		this.errorMsg = errorMsg;
+	}
+
+	public Uri getUri() {
+		return uri;
+	}
+
+	@Nullable
+	public AttachmentItem getItem() {
+		return item;
+	}
+
+	public boolean hasError() {
+		return item == null;
+	}
+
+	@Nullable
+	public String getErrorMsg() {
+		return errorMsg;
+	}
+
+}

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

@@ -0,0 +1,24 @@
+package org.briarproject.briar.android.attachment;
+
+import android.arch.lifecycle.LiveData;
+import android.net.Uri;
+import android.support.annotation.UiThread;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.briar.api.messaging.AttachmentHeader;
+
+import java.util.Collection;
+import java.util.List;
+
+@UiThread
+@NotNullByDefault
+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/AttachmentModule.java

@@ -0,0 +1,43 @@
+package org.briarproject.briar.android.attachment;
+
+import android.app.Application;
+
+import javax.inject.Singleton;
+
+import dagger.Module;
+import dagger.Provides;
+
+import static org.briarproject.briar.android.attachment.AttachmentDimensions.getAttachmentDimensions;
+
+@Module
+public class AttachmentModule {
+
+	@Provides
+	ImageHelper provideImageHelper(ImageHelperImpl imageHelper) {
+		return imageHelper;
+	}
+
+	@Provides
+	ImageSizeCalculator provideImageSizeCalculator(ImageHelper imageHelper) {
+		return new ImageSizeCalculator(imageHelper);
+	}
+
+	@Provides
+	AttachmentDimensions provideAttachmentDimensions(Application app) {
+		return getAttachmentDimensions(app.getResources());
+	}
+
+	@Provides
+	@Singleton
+	AttachmentRetriever provideAttachmentRetriever(
+			AttachmentRetrieverImpl attachmentRetriever) {
+		return attachmentRetriever;
+	}
+
+	@Provides
+	@Singleton
+	AttachmentCreator provideAttachmentCreator(
+			AttachmentCreatorImpl attachmentCreator) {
+		return attachmentCreator;
+	}
+}

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

@@ -0,0 +1,30 @@
+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;
+
+	public AttachmentResult(Collection<AttachmentItemResult> itemResults,
+			boolean finished) {
+		this.itemResults = itemResults;
+		this.finished = finished;
+	}
+
+	public Collection<AttachmentItemResult> getItemResults() {
+		return itemResults;
+	}
+
+	public boolean isFinished() {
+		return finished;
+	}
+
+}

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

@@ -0,0 +1,29 @@
+package org.briarproject.briar.android.attachment;
+
+import android.support.annotation.Nullable;
+
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.sync.MessageId;
+import org.briarproject.briar.api.messaging.Attachment;
+import org.briarproject.briar.api.messaging.AttachmentHeader;
+
+import java.io.InputStream;
+import java.util.List;
+
+@NotNullByDefault
+public interface AttachmentRetriever {
+
+	void cachePut(MessageId messageId, List<AttachmentItem> attachments);
+
+	@Nullable
+	List<AttachmentItem> cacheGet(MessageId messageId);
+
+	Attachment getMessageAttachment(AttachmentHeader h) throws DbException;
+
+	/**
+	 * Creates an {@link AttachmentItem} from the {@link Attachment}'s
+	 * {@link InputStream} which will be closed when this method returns.
+	 */
+	AttachmentItem getAttachmentItem(Attachment a, boolean needsSize);
+}

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

@@ -0,0 +1,129 @@
+package org.briarproject.briar.android.attachment;
+
+import android.support.annotation.Nullable;
+
+import org.briarproject.bramble.api.db.DbException;
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.bramble.api.sync.MessageId;
+import org.briarproject.briar.api.messaging.Attachment;
+import org.briarproject.briar.api.messaging.AttachmentHeader;
+import org.briarproject.briar.api.messaging.MessagingManager;
+
+import java.io.BufferedInputStream;
+import java.io.InputStream;
+import java.util.List;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.logging.Logger;
+
+import javax.inject.Inject;
+
+import static java.util.logging.Level.WARNING;
+import static java.util.logging.Logger.getLogger;
+
+@NotNullByDefault
+class AttachmentRetrieverImpl implements AttachmentRetriever {
+
+	private static final Logger LOG =
+			getLogger(AttachmentRetrieverImpl.class.getName());
+
+	private final MessagingManager messagingManager;
+	private final ImageHelper imageHelper;
+	private final ImageSizeCalculator imageSizeCalculator;
+	private final int defaultSize;
+	private final int minWidth, maxWidth;
+	private final int minHeight, maxHeight;
+
+	private final Map<MessageId, List<AttachmentItem>> attachmentCache =
+			new ConcurrentHashMap<>();
+
+	@Inject
+	AttachmentRetrieverImpl(MessagingManager messagingManager,
+			AttachmentDimensions dimensions, ImageHelper imageHelper,
+			ImageSizeCalculator imageSizeCalculator) {
+		this.messagingManager = messagingManager;
+		this.imageHelper = imageHelper;
+		this.imageSizeCalculator = imageSizeCalculator;
+		defaultSize = dimensions.defaultSize;
+		minWidth = dimensions.minWidth;
+		maxWidth = dimensions.maxWidth;
+		minHeight = dimensions.minHeight;
+		maxHeight = dimensions.maxHeight;
+	}
+
+	@Override
+	public void cachePut(MessageId messageId,
+			List<AttachmentItem> attachments) {
+		attachmentCache.put(messageId, attachments);
+	}
+
+	@Override
+	@Nullable
+	public List<AttachmentItem> cacheGet(MessageId messageId) {
+		return attachmentCache.get(messageId);
+	}
+
+	@Override
+	public Attachment getMessageAttachment(AttachmentHeader h)
+			throws DbException {
+		return messagingManager.getAttachment(h);
+	}
+
+	@Override
+	public AttachmentItem getAttachmentItem(Attachment a, boolean needsSize) {
+		AttachmentHeader h = a.getHeader();
+		if (!needsSize) {
+			String extension =
+					imageHelper.getExtensionFromMimeType(h.getContentType());
+			boolean hasError = false;
+			if (extension == null) {
+				extension = "";
+				hasError = true;
+			}
+			return new AttachmentItem(h, 0, 0, extension, 0, 0, hasError);
+		}
+
+		InputStream is = new BufferedInputStream(a.getStream());
+		Size size = imageSizeCalculator.getSize(is, h.getContentType());
+
+		// calculate thumbnail size
+		Size thumbnailSize = new Size(defaultSize, defaultSize, size.mimeType);
+		if (!size.error) {
+			thumbnailSize =
+					getThumbnailSize(size.width, size.height, size.mimeType);
+		}
+		// 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(h, size.width, size.height, extension,
+				thumbnailSize.width, thumbnailSize.height, hasError);
+	}
+
+	private Size getThumbnailSize(int width, int height, String mimeType) {
+		float widthPercentage = maxWidth / (float) width;
+		float heightPercentage = maxHeight / (float) height;
+		float scaleFactor = Math.min(widthPercentage, heightPercentage);
+		if (scaleFactor > 1) scaleFactor = 1f;
+		int thumbnailWidth = (int) (width * scaleFactor);
+		int thumbnailHeight = (int) (height * scaleFactor);
+		if (thumbnailWidth < minWidth || thumbnailHeight < minHeight) {
+			widthPercentage = minWidth / (float) width;
+			heightPercentage = minHeight / (float) height;
+			scaleFactor = Math.max(widthPercentage, heightPercentage);
+			thumbnailWidth = (int) (width * scaleFactor);
+			thumbnailHeight = (int) (height * scaleFactor);
+			if (thumbnailWidth > maxWidth) thumbnailWidth = maxWidth;
+			if (thumbnailHeight > maxHeight) thumbnailHeight = maxHeight;
+		}
+		return new Size(thumbnailWidth, thumbnailHeight, mimeType);
+	}
+}

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;
 
@@ -7,7 +7,7 @@ import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
 import java.io.InputStream;
 
 @NotNullByDefault
-interface ImageHelper {
+public interface ImageHelper {
 
 	DecodeResult decodeStream(InputStream is);
 

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

@@ -0,0 +1,39 @@
+package org.briarproject.briar.android.attachment;
+
+import android.graphics.BitmapFactory;
+import android.support.annotation.Nullable;
+import android.webkit.MimeTypeMap;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+
+import java.io.InputStream;
+
+import javax.annotation.concurrent.Immutable;
+import javax.inject.Inject;
+
+@Immutable
+@NotNullByDefault
+class ImageHelperImpl implements ImageHelper {
+
+	@Inject
+	ImageHelperImpl() {
+	}
+
+	@Override
+	public DecodeResult decodeStream(InputStream is) {
+		BitmapFactory.Options options = new BitmapFactory.Options();
+		options.inJustDecodeBounds = true;
+		BitmapFactory.decodeStream(is, null, options);
+		String mimeType = options.outMimeType;
+		if (mimeType == null) mimeType = "";
+		return new DecodeResult(options.outWidth, options.outHeight,
+				mimeType);
+	}
+
+	@Nullable
+	@Override
+	public String getExtensionFromMimeType(String mimeType) {
+		MimeTypeMap mimeTypeMap = MimeTypeMap.getSingleton();
+		return mimeTypeMap.getExtensionFromMimeType(mimeType);
+	}
+}

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

@@ -0,0 +1,94 @@
+package org.briarproject.briar.android.attachment;
+
+import android.support.media.ExifInterface;
+
+import com.bumptech.glide.util.MarkEnforcingInputStream;
+
+import org.briarproject.bramble.api.nullsafety.NotNullByDefault;
+import org.briarproject.briar.android.attachment.ImageHelper.DecodeResult;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.logging.Logger;
+
+import static android.support.media.ExifInterface.ORIENTATION_ROTATE_270;
+import static android.support.media.ExifInterface.ORIENTATION_ROTATE_90;
+import static android.support.media.ExifInterface.ORIENTATION_TRANSPOSE;
+import static android.support.media.ExifInterface.ORIENTATION_TRANSVERSE;
+import static android.support.media.ExifInterface.TAG_IMAGE_LENGTH;
+import static android.support.media.ExifInterface.TAG_IMAGE_WIDTH;
+import static android.support.media.ExifInterface.TAG_ORIENTATION;
+import static java.util.logging.Level.WARNING;
+import static java.util.logging.Logger.getLogger;
+import static org.briarproject.bramble.util.LogUtils.logException;
+
+@NotNullByDefault
+class ImageSizeCalculator {
+
+	private static final Logger LOG =
+			getLogger(ImageSizeCalculator.class.getName());
+
+	private static final int READ_LIMIT = 1024 * 8192;
+
+	private final ImageHelper imageHelper;
+
+	ImageSizeCalculator(ImageHelper imageHelper) {
+		this.imageHelper = imageHelper;
+	}
+
+	Size getSize(InputStream is, String contentType) {
+		Size size = new Size();
+		is = new MarkEnforcingInputStream(is);
+		is.mark(READ_LIMIT);
+		if (contentType.equals("image/jpeg")) {
+			try {
+				// use exif to get size
+				size = getSizeFromExif(is);
+				is.reset();
+			} catch (IOException e) {
+				logException(LOG, WARNING, e);
+			}
+		}
+		if (size.error) {
+			// need to mark again to re-add read limit
+			is.mark(READ_LIMIT);
+			try {
+				// use BitmapFactory to get size
+				size = getSizeFromBitmap(is);
+				is.reset();
+			} catch (IOException e) {
+				logException(LOG, WARNING, e);
+			}
+		}
+		return size;
+	}
+
+	/**
+	 * Gets the size of a JPEG {@link InputStream} if EXIF info is available.
+	 */
+	private Size getSizeFromExif(InputStream is) throws IOException {
+		ExifInterface exif = new ExifInterface(is);
+		// these can return 0 independent of default value
+		int width = exif.getAttributeInt(TAG_IMAGE_WIDTH, 0);
+		int height = exif.getAttributeInt(TAG_IMAGE_LENGTH, 0);
+		if (width == 0 || height == 0) return new Size();
+		int orientation = exif.getAttributeInt(TAG_ORIENTATION, 0);
+		if (orientation == ORIENTATION_ROTATE_90 ||
+				orientation == ORIENTATION_ROTATE_270 ||
+				orientation == ORIENTATION_TRANSVERSE ||
+				orientation == ORIENTATION_TRANSPOSE) {
+			//noinspection SuspiciousNameCombination
+			return new Size(height, width, "image/jpeg");
+		}
+		return new Size(width, height, "image/jpeg");
+	}
+
+	/**
+	 * Gets the size of any image {@link InputStream}.
+	 */
+	private Size getSizeFromBitmap(InputStream is) {
+		DecodeResult result = imageHelper.decodeStream(is);
+		if (result.width < 1 || result.height < 1) return new Size();
+		return new Size(result.width, result.height, result.mimeType);
+	}
+}

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

@@ -0,0 +1,23 @@
+package org.briarproject.briar.android.attachment;
+
+class Size {
+
+	final int width;
+	final int height;
+	final String mimeType;
+	final boolean error;
+
+	Size(int width, int height, String mimeType) {
+		this.width = width;
+		this.height = height;
+		this.mimeType = mimeType;
+		this.error = false;
+	}
+
+	Size() {
+		this.width = 0;
+		this.height = 0;
+		this.mimeType = "";
+		this.error = true;
+	}
+}

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/NicknameFragment.java

@@ -82,19 +82,20 @@ public class NicknameFragment extends BaseFragment {
 
 	@Nullable
 	private String getNicknameOrNull() {
-		Editable name = contactNameInput.getText();
-		if (name == null || name.toString().trim().length() == 0) {
+		Editable text = contactNameInput.getText();
+		if (text == null || text.toString().trim().length() == 0) {
 			contactNameLayout.setError(getString(R.string.nickname_missing));
 			contactNameInput.requestFocus();
 			return null;
 		}
-		if (utf8IsTooLong(name.toString(), MAX_AUTHOR_NAME_LENGTH)) {
+		String name = text.toString().trim();
+		if (utf8IsTooLong(name, MAX_AUTHOR_NAME_LENGTH)) {
 			contactNameLayout.setError(getString(R.string.name_too_long));
 			contactNameInput.requestFocus();
 			return null;
 		}
 		contactNameLayout.setError(null);
-		return name.toString().trim();
+		return name;
 	}
 
 	private void onAddButtonClicked() {

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(),
-							lastPoll));
+					items.add(new PendingContactItem(p, state, 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/AliasDialogFragment.java

@@ -82,7 +82,7 @@ public class AliasDialogFragment extends AppCompatDialogFragment {
 	}
 
 	private void onSetButtonClicked() {
-		String alias = aliasEditText.getText().toString();
+		String alias = aliasEditText.getText().toString().trim();
 		if (toUtf8(alias).length > MAX_AUTHOR_NAME_LENGTH) {
 			aliasEditLayout.setError(getString(R.string.name_too_long));
 		} else {

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

@@ -1,264 +0,0 @@
-package org.briarproject.briar.android.conversation;
-
-import android.graphics.BitmapFactory;
-import android.graphics.BitmapFactory.Options;
-import android.support.annotation.Nullable;
-import android.support.media.ExifInterface;
-import android.webkit.MimeTypeMap;
-
-import com.bumptech.glide.util.MarkEnforcingInputStream;
-
-import org.briarproject.bramble.api.Pair;
-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.api.messaging.Attachment;
-import org.briarproject.briar.api.messaging.AttachmentHeader;
-import org.briarproject.briar.api.messaging.MessagingManager;
-
-import java.io.BufferedInputStream;
-import java.io.IOException;
-import java.io.InputStream;
-import java.util.ArrayList;
-import java.util.List;
-import java.util.Map;
-import java.util.concurrent.ConcurrentHashMap;
-import java.util.logging.Logger;
-
-import static android.support.media.ExifInterface.ORIENTATION_ROTATE_270;
-import static android.support.media.ExifInterface.ORIENTATION_ROTATE_90;
-import static android.support.media.ExifInterface.ORIENTATION_TRANSPOSE;
-import static android.support.media.ExifInterface.ORIENTATION_TRANSVERSE;
-import static android.support.media.ExifInterface.TAG_IMAGE_LENGTH;
-import static android.support.media.ExifInterface.TAG_IMAGE_WIDTH;
-import static android.support.media.ExifInterface.TAG_ORIENTATION;
-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;
-
-@NotNullByDefault
-class AttachmentController {
-
-	private static final Logger LOG =
-			getLogger(AttachmentController.class.getName());
-	private static final int READ_LIMIT = 1024 * 8192;
-
-	private final MessagingManager messagingManager;
-	private final ImageHelper imageHelper;
-	private final int defaultSize;
-	private final int minWidth, maxWidth;
-	private final int minHeight, maxHeight;
-
-	private final Map<MessageId, List<AttachmentItem>> attachmentCache =
-			new ConcurrentHashMap<>();
-
-	AttachmentController(MessagingManager messagingManager,
-			AttachmentDimensions dimensions, ImageHelper imageHelper) {
-		this.messagingManager = messagingManager;
-		this.imageHelper = imageHelper;
-		defaultSize = dimensions.defaultSize;
-		minWidth = dimensions.minWidth;
-		maxWidth = dimensions.maxWidth;
-		minHeight = dimensions.minHeight;
-		maxHeight = dimensions.maxHeight;
-	}
-
-	AttachmentController(MessagingManager messagingManager,
-			AttachmentDimensions dimensions) {
-		this(messagingManager, dimensions, new ImageHelper() {
-			@Override
-			public DecodeResult decodeStream(InputStream is) {
-				Options options = new Options();
-				options.inJustDecodeBounds = true;
-				BitmapFactory.decodeStream(is, null, options);
-				String mimeType = options.outMimeType;
-				if (mimeType == null) mimeType = "";
-				return new DecodeResult(options.outWidth, options.outHeight,
-						mimeType);
-			}
-
-			@Nullable
-			@Override
-			public String getExtensionFromMimeType(String mimeType) {
-				MimeTypeMap mimeTypeMap = MimeTypeMap.getSingleton();
-				return mimeTypeMap.getExtensionFromMimeType(mimeType);
-			}
-		});
-	}
-
-	void put(MessageId messageId, List<AttachmentItem> attachments) {
-		attachmentCache.put(messageId, attachments);
-	}
-
-	@Nullable
-	List<AttachmentItem> get(MessageId messageId) {
-		return attachmentCache.get(messageId);
-	}
-
-	@DatabaseExecutor
-	List<Pair<AttachmentHeader, Attachment>> getMessageAttachments(
-			List<AttachmentHeader> headers) throws DbException {
-		long start = now();
-		List<Pair<AttachmentHeader, Attachment>> attachments =
-				new ArrayList<>(headers.size());
-		for (AttachmentHeader h : headers) {
-			Attachment a = messagingManager.getAttachment(h.getMessageId());
-			attachments.add(new Pair<>(h, a));
-		}
-		logDuration(LOG, "Loading attachment", start);
-		return attachments;
-	}
-
-	/**
-	 * Creates {@link AttachmentItem}s from the passed headers and Attachments.
-	 * <p>
-	 * Note: This closes the {@link Attachment}'s {@link InputStream}.
-	 */
-	List<AttachmentItem> getAttachmentItems(
-			List<Pair<AttachmentHeader, Attachment>> attachments) {
-		boolean needsSize = attachments.size() == 1;
-		List<AttachmentItem> items = new ArrayList<>(attachments.size());
-		for (Pair<AttachmentHeader, Attachment> a : attachments) {
-			AttachmentItem item =
-					getAttachmentItem(a.getFirst(), a.getSecond(), needsSize);
-			items.add(item);
-		}
-		return items;
-	}
-
-	/**
-	 * Creates an {@link AttachmentItem} from the {@link Attachment}'s
-	 * {@link InputStream} which will be closed when this method returns.
-	 */
-	AttachmentItem getAttachmentItem(AttachmentHeader h, Attachment a,
-			boolean needsSize) {
-		MessageId messageId = h.getMessageId();
-		if (!needsSize) {
-			String mimeType = h.getContentType();
-			String extension = imageHelper.getExtensionFromMimeType(mimeType);
-			boolean hasError = false;
-			if (extension == null) {
-				extension = "";
-				hasError = true;
-			}
-			return new AttachmentItem(messageId, 0, 0, mimeType, extension, 0,
-					0, hasError);
-		}
-
-		Size size = new Size();
-		InputStream is = new MarkEnforcingInputStream(
-				new BufferedInputStream(a.getStream()));
-		is.mark(READ_LIMIT);
-		try {
-			// use exif to get size
-			if (h.getContentType().equals("image/jpeg")) {
-				size = getSizeFromExif(is);
-			}
-		} catch (IOException e) {
-			logException(LOG, WARNING, e);
-		}
-		try {
-			// use BitmapFactory to get size
-			if (size.error) {
-				is.reset();
-				// need to mark again to re-add read limit
-				is.mark(READ_LIMIT);
-				size = getSizeFromBitmap(is);
-			}
-		} catch (IOException e) {
-			logException(LOG, WARNING, e);
-		} finally {
-			tryToClose(is, LOG, WARNING);
-		}
-
-		// calculate thumbnail size
-		Size thumbnailSize = new Size(defaultSize, defaultSize, size.mimeType);
-		if (!size.error) {
-			thumbnailSize =
-					getThumbnailSize(size.width, size.height, size.mimeType);
-		}
-		// get file extension
-		String extension = imageHelper.getExtensionFromMimeType(size.mimeType);
-		boolean hasError = extension == null || size.error;
-		if (extension == null) extension = "";
-		return new AttachmentItem(messageId, size.width, size.height,
-				size.mimeType, extension, thumbnailSize.width,
-				thumbnailSize.height, hasError);
-	}
-
-	/**
-	 * Gets the size of a JPEG {@link InputStream} if EXIF info is available.
-	 */
-	private Size getSizeFromExif(InputStream is) throws IOException {
-		ExifInterface exif = new ExifInterface(is);
-		// these can return 0 independent of default value
-		int width = exif.getAttributeInt(TAG_IMAGE_WIDTH, 0);
-		int height = exif.getAttributeInt(TAG_IMAGE_LENGTH, 0);
-		if (width == 0 || height == 0) return new Size();
-		int orientation = exif.getAttributeInt(TAG_ORIENTATION, 0);
-		if (orientation == ORIENTATION_ROTATE_90 ||
-				orientation == ORIENTATION_ROTATE_270 ||
-				orientation == ORIENTATION_TRANSVERSE ||
-				orientation == ORIENTATION_TRANSPOSE) {
-			//noinspection SuspiciousNameCombination
-			return new Size(height, width, "image/jpeg");
-		}
-		return new Size(width, height, "image/jpeg");
-	}
-
-	/**
-	 * Gets the size of any image {@link InputStream}.
-	 */
-	private Size getSizeFromBitmap(InputStream is) {
-		DecodeResult result = imageHelper.decodeStream(is);
-		if (result.width < 1 || result.height < 1) return new Size();
-		return new Size(result.width, result.height, result.mimeType);
-	}
-
-	private Size getThumbnailSize(int width, int height, String mimeType) {
-		float widthPercentage = maxWidth / (float) width;
-		float heightPercentage = maxHeight / (float) height;
-		float scaleFactor = Math.min(widthPercentage, heightPercentage);
-		if (scaleFactor > 1) scaleFactor = 1f;
-		int thumbnailWidth = (int) (width * scaleFactor);
-		int thumbnailHeight = (int) (height * scaleFactor);
-		if (thumbnailWidth < minWidth || thumbnailHeight < minHeight) {
-			widthPercentage = minWidth / (float) width;
-			heightPercentage = minHeight / (float) height;
-			scaleFactor = Math.max(widthPercentage, heightPercentage);
-			thumbnailWidth = (int) (width * scaleFactor);
-			thumbnailHeight = (int) (height * scaleFactor);
-			if (thumbnailWidth > maxWidth) thumbnailWidth = maxWidth;
-			if (thumbnailHeight > maxHeight) thumbnailHeight = maxHeight;
-		}
-		return new Size(thumbnailWidth, thumbnailHeight, mimeType);
-	}
-
-	private static class Size {
-
-		private final int width;
-		private final int height;
-		private final String mimeType;
-		private final boolean error;
-
-		private Size(int width, int height, String mimeType) {
-			this.width = width;
-			this.height = height;
-			this.mimeType = mimeType;
-			this.error = false;
-		}
-
-		private Size() {
-			this.width = 0;
-			this.height = 0;
-			this.mimeType = "";
-			this.error = true;
-		}
-	}
-
-}

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;
@@ -30,14 +29,15 @@ 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;
+import org.briarproject.bramble.api.db.NoSuchMessageException;
 import org.briarproject.bramble.api.event.Event;
 import org.briarproject.bramble.api.event.EventBus;
 import org.briarproject.bramble.api.event.EventListener;
@@ -46,13 +46,14 @@ 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 +64,9 @@ 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;
@@ -81,8 +81,8 @@ 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.messaging.event.AttachmentReceivedEvent;
 import org.briarproject.briar.api.privategroup.invitation.GroupInvitationManager;
 
 import java.util.ArrayList;
@@ -92,7 +92,6 @@ 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;
@@ -110,15 +109,16 @@ import static android.support.v7.util.SortedList.INVALID_POSITION;
 import static android.view.Gravity.RIGHT;
 import static android.widget.Toast.LENGTH_SHORT;
 import static java.util.Collections.emptyList;
+import static java.util.Collections.singletonList;
 import static java.util.Collections.sort;
 import static java.util.Objects.requireNonNull;
 import static java.util.logging.Level.INFO;
 import static java.util.logging.Level.WARNING;
+import static java.util.logging.Logger.getLogger;
 import static org.briarproject.bramble.util.LogUtils.logDuration;
 import static org.briarproject.bramble.util.LogUtils.logException;
 import static org.briarproject.bramble.util.LogUtils.now;
 import static org.briarproject.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 +128,7 @@ 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;
@@ -135,13 +136,13 @@ import static uk.co.samuelwall.materialtaptargetprompt.MaterialTapTargetPrompt.S
 @MethodsNotNullByDefault
 @ParametersNotNullByDefault
 public class ConversationActivity extends BriarActivity
-		implements EventListener, ConversationListener, SendListener,
-		TextCache, AttachmentCache, AttachImageListener {
+		implements EventListener, ConversationListener, TextCache,
+		AttachmentCache, AttachmentListener {
 
 	public static final String CONTACT_ID = "briar.CONTACT_ID";
 
 	private static final Logger LOG =
-			Logger.getLogger(ConversationActivity.class.getName());
+			getLogger(ConversationActivity.class.getName());
 
 	private static final int TRANSITION_DURATION_MS = 500;
 	private static final int ONBOARDING_DELAY_MS = 250;
@@ -151,10 +152,9 @@ 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 +166,6 @@ 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;
@@ -179,12 +175,14 @@ public class ConversationActivity extends BriarActivity
 	volatile GroupInvitationManager groupInvitationManager;
 
 	private final Map<MessageId, String> textCache = new ConcurrentHashMap<>();
+	private final Map<MessageId, PrivateMessageHeader> missingAttachments =
+			new ConcurrentHashMap<>();
 	private final Observer<String> contactNameObserver = name -> {
 		requireNonNull(name);
 		loadMessages();
 	};
 
-	private AttachmentController attachmentController;
+	private AttachmentRetriever attachmentRetriever;
 	private ConversationViewModel viewModel;
 	private ConversationVisitor visitor;
 	private ConversationAdapter adapter;
@@ -219,7 +217,7 @@ 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 +240,7 @@ 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 +259,13 @@ 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 +300,7 @@ 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);
 		}
 	}
@@ -442,29 +440,40 @@ public class ConversationActivity extends BriarActivity
 		});
 	}
 
-	private void eagerlyLoadMessageSize(PrivateMessageHeader h)
-			throws DbException {
-		MessageId id = h.getId();
-		// If the message has text, load it
-		if (h.hasText()) {
-			String text = textCache.get(id);
-			if (text == null) {
-				LOG.info("Eagerly loading text for latest message");
-				text = messagingManager.getMessageText(id);
-				textCache.put(id, text);
+	private void eagerlyLoadMessageSize(PrivateMessageHeader h) {
+		try {
+			MessageId id = h.getId();
+			// If the message has text, load it
+			if (h.hasText()) {
+				String text = textCache.get(id);
+				if (text == null) {
+					LOG.info("Eagerly loading text for latest message");
+					text = messagingManager.getMessageText(id);
+					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<AttachmentItem> items = attachmentController.get(id);
-			if (items == null) {
-				LOG.info("Eagerly loading image size for latest message");
-				items = attachmentController.getAttachmentItems(
-						attachmentController.getMessageAttachments(
-								h.getAttachmentHeaders()));
-				attachmentController.put(id, items);
+			// If the message has a single image, load its size - for multiple
+			// images we use a grid so the size is fixed
+			List<AttachmentHeader> headers = h.getAttachmentHeaders();
+			if (headers.size() == 1) {
+				List<AttachmentItem> items = attachmentRetriever.cacheGet(id);
+				if (items == null) {
+					LOG.info("Eagerly loading image size for latest message");
+					AttachmentHeader header = headers.get(0);
+					try {
+						Attachment a = attachmentRetriever
+								.getMessageAttachment(header);
+						AttachmentItem item =
+								attachmentRetriever.getAttachmentItem(a, true);
+						attachmentRetriever.cachePut(id, singletonList(item));
+					} catch (NoSuchMessageException e) {
+						LOG.info("Attachment not received yet");
+						missingAttachments.put(header.getMessageId(), h);
+					}
+				}
 			}
+		} catch (DbException e) {
+			logException(LOG, WARNING, e);
 		}
 	}
 
@@ -475,8 +484,10 @@ public class ConversationActivity extends BriarActivity
 				adapter.incrementRevision();
 				textInputView.setReady(true);
 				// start observing onboarding after enabling
-				viewModel.showImageOnboarding().observeEvent(this,
-						this::showImageOnboarding);
+				if (featureFlags.shouldEnableImageAttachments()) {
+					viewModel.showImageOnboarding().observeEvent(this,
+							this::showImageOnboarding);
+				}
 				List<ConversationItem> items = createItems(headers);
 				adapter.addAll(items);
 				list.showData();
@@ -512,7 +523,7 @@ 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);
 			}
@@ -540,16 +551,30 @@ public class ConversationActivity extends BriarActivity
 				&& adapter.isScrolledToBottom(layoutManager);
 	}
 
-	private void loadMessageAttachments(MessageId messageId,
-			List<AttachmentHeader> headers) {
+	private void loadMessageAttachments(PrivateMessageHeader h) {
+		// TODO: Use placeholders for missing/invalid attachments
 		runOnDbThread(() -> {
 			try {
-				List<Pair<AttachmentHeader, Attachment>> attachments =
-						attachmentController.getMessageAttachments(headers);
 				// TODO move getting the items off to IoExecutor, if size == 1
-				List<AttachmentItem> items =
-						attachmentController.getAttachmentItems(attachments);
-				displayMessageAttachments(messageId, items);
+				List<AttachmentHeader> headers = h.getAttachmentHeaders();
+				boolean needsSize = headers.size() == 1;
+				List<AttachmentItem> items = new ArrayList<>(headers.size());
+				for (AttachmentHeader header : headers) {
+					try {
+						Attachment a = attachmentRetriever
+								.getMessageAttachment(header);
+						AttachmentItem item = attachmentRetriever
+								.getAttachmentItem(a, needsSize);
+						items.add(item);
+					} catch (NoSuchMessageException e) {
+						LOG.info("Attachment not received yet");
+						missingAttachments.put(header.getMessageId(), h);
+						return;
+					}
+				}
+				// Don't cache items unless all are present and valid
+				attachmentRetriever.cachePut(h.getId(), items);
+				displayMessageAttachments(h.getId(), items);
 			} catch (DbException e) {
 				logException(LOG, WARNING, e);
 			}
@@ -559,7 +584,6 @@ 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) {
@@ -573,6 +597,13 @@ public class ConversationActivity extends BriarActivity
 
 	@Override
 	public void eventOccurred(Event e) {
+		if (e instanceof AttachmentReceivedEvent) {
+			AttachmentReceivedEvent a = (AttachmentReceivedEvent) e;
+			if (a.getContactId().equals(contactId)) {
+				LOG.info("Attachment received");
+				onAttachmentReceived(a.getMessageId());
+			}
+		}
 		if (e instanceof ContactRemovedEvent) {
 			ContactRemovedEvent c = (ContactRemovedEvent) e;
 			if (c.getContactId().equals(contactId)) {
@@ -623,6 +654,15 @@ public class ConversationActivity extends BriarActivity
 			scrollToBottom();
 	}
 
+	@UiThread
+	private void onAttachmentReceived(MessageId attachmentId) {
+		PrivateMessageHeader h = missingAttachments.remove(attachmentId);
+		if (h != null) {
+			LOG.info("Missing attachment received");
+			loadMessageAttachments(h);
+		}
+	}
+
 	@UiThread
 	private void onNewConversationMessage(ConversationMessageHeader h) {
 		if (h instanceof ConversationRequest ||
@@ -658,12 +698,21 @@ public class ConversationActivity extends BriarActivity
 	}
 
 	@Override
-	public void onSendClick(@Nullable String text, List<Uri> imageUris) {
-		if (isNullOrEmpty(text) && imageUris.isEmpty())
+	public void onTooManyAttachments() {
+		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 +725,6 @@ 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 +774,7 @@ 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());
@@ -901,11 +949,11 @@ public class ConversationActivity extends BriarActivity
 	}
 
 	@Override
-	public List<AttachmentItem> getAttachmentItems(MessageId m,
-			List<AttachmentHeader> headers) {
-		List<AttachmentItem> attachments = attachmentController.get(m);
+	public List<AttachmentItem> getAttachmentItems(PrivateMessageHeader h) {
+		List<AttachmentItem> attachments =
+				attachmentRetriever.cacheGet(h.getId());
 		if (attachments == null) {
-			loadMessageAttachments(m, headers);
+			loadMessageAttachments(h);
 			return emptyList();
 		}
 		return attachments;

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

@@ -5,17 +5,14 @@ import android.arch.lifecycle.AndroidViewModel;
 import android.arch.lifecycle.LiveData;
 import android.arch.lifecycle.MutableLiveData;
 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;
@@ -27,19 +24,19 @@ 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 +47,19 @@ 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.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 +67,13 @@ 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 +82,7 @@ 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 +93,39 @@ public class ConversationViewModel extends AndroidViewModel {
 			new MutableLiveData<>();
 	private final MutableLiveData<Boolean> contactDeleted =
 			new MutableLiveData<>();
-	private final MutableLiveData<GroupId> messagingGroupId =
-			new MutableLiveData<>();
-	private final MutableLiveData<PrivateMessageHeader> addedHeader =
-			new MutableLiveData<>();
+	private final MutableLiveEvent<PrivateMessageHeader> addedHeader =
+			new MutableLiveEvent<>();
 
 	@Inject
 	ConversationViewModel(Application application,
 			@DatabaseExecutor Executor dbExecutor,
-			@CryptoExecutor Executor cryptoExecutor, TransactionManager db,
-			MessagingManager messagingManager, ContactManager contactManager,
+			TransactionManager db,
+			MessagingManager messagingManager,
+			ContactManager contactManager,
 			SettingsManager settingsManager,
-			PrivateMessageFactory privateMessageFactory) {
+			PrivateMessageFactory privateMessageFactory,
+			AttachmentRetriever attachmentRetriever,
+			AttachmentCreator attachmentCreator) {
 		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,
-				getAttachmentDimensions(application.getResources()));
+		this.attachmentRetriever = attachmentRetriever;
+		this.attachmentCreator = attachmentCreator;
+		messagingGroupId = Transformations
+				.map(contact, c -> messagingManager.getContactGroup(c).getId());
 		contactDeleted.setValue(false);
 	}
 
+	@Override
+	protected void onCleared() {
+		super.onCleared();
+		attachmentCreator.deleteUnsentAttachments();
+	}
+
 	/**
 	 * Setting the {@link ContactId} automatically triggers loading of other
 	 * data.
@@ -176,25 +181,42 @@ public class ConversationViewModel extends AndroidViewModel {
 		});
 	}
 
-	void sendMessage(@Nullable String text, List<Uri> uris, long timestamp) {
-		if (messagingGroupId.getValue() == null) loadGroupId();
+	@UiThread
+	void sendMessage(@Nullable String text,
+			List<AttachmentHeader> headers, long timestamp) {
+		// messagingGroupId is loaded with the contact
 		observeForeverOnce(messagingGroupId, groupId -> {
-			if (groupId == null) return;
-			// calls through to creating and storing the message
-			storeAttachments(groupId, text, uris, timestamp);
+			requireNonNull(groupId);
+			observeForeverOnce(imageSupport, hasImageSupport -> {
+				requireNonNull(hasImageSupport);
+				createMessage(groupId, text, headers, timestamp,
+						hasImageSupport);
+			});
 		});
 	}
 
-	private void loadGroupId() {
-		if (contactId == null) throw new IllegalStateException();
-		dbExecutor.execute(() -> {
-			try {
-				messagingGroupId.postValue(
-						messagingManager.getConversationId(contactId));
-			} catch (DbException e) {
-				logException(LOG, WARNING, e);
-			}
-		});
+	@Override
+	@UiThread
+	public LiveData<AttachmentResult> storeAttachments(Collection<Uri> uris,
+			boolean restart) {
+		if (restart) {
+			return attachmentCreator.getLiveAttachments();
+		} else {
+			// messagingGroupId is loaded with the contact
+			return attachmentCreator.storeAttachments(messagingGroupId, uris);
+		}
+	}
+
+	@Override
+	@UiThread
+	public List<AttachmentHeader> getAttachmentHeadersForSending() {
+		return attachmentCreator.getAttachmentHeadersForSending();
+	}
+
+	@Override
+	@UiThread
+	public void cancel() {
+		attachmentCreator.cancel();
 	}
 
 	@DatabaseExecutor
@@ -252,75 +274,26 @@ public class ConversationViewModel extends AndroidViewModel {
 		});
 	}
 
-	private void storeAttachments(GroupId groupId, @Nullable String text,
-			List<Uri> uris, long timestamp) {
-		dbExecutor.execute(() -> {
-			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;
+	private void createMessage(GroupId groupId, @Nullable String text,
+			List<AttachmentHeader> headers, long timestamp,
+			boolean hasImageSupport) {
 		try {
-			ContentResolver contentResolver =
-					getApplication().getContentResolver();
-			is = contentResolver.openInputStream(uri);
-			if (is == null) throw new IOException();
-			String contentType = contentResolver.getType(uri);
-			if (contentType == null) throw new IOException("null content type");
-			AttachmentHeader h = messagingManager
-					.addLocalAttachment(groupId, timestamp, contentType, is);
-			is.close();
-			// re-open stream to get AttachmentItem
-			is = contentResolver.openInputStream(uri);
-			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);
+			PrivateMessage pm;
+			if (hasImageSupport) {
+				pm = privateMessageFactory.createPrivateMessage(groupId,
+						timestamp, text, headers);
+			} else {
+				pm = privateMessageFactory.createLegacyPrivateMessage(
+						groupId, timestamp, requireNonNull(text));
+			}
+			storeMessage(pm);
+		} catch (FormatException e) {
+			throw new AssertionError(e);
 		}
 	}
 
-	private void createMessage(GroupId groupId, @Nullable String text,
-			List<AttachmentHeader> attachments, List<AttachmentItem> aItems,
-			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) {
+	private void storeMessage(PrivateMessage m) {
+		attachmentCreator.onAttachmentsSent(m.getMessage().getId());
 		dbExecutor.execute(() -> {
 			try {
 				long start = now();
@@ -330,22 +303,17 @@ 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
-	void onAddedPrivateMessageSeen() {
-		addedHeader.setValue(null);
-	}
-
-	AttachmentController getAttachmentController() {
-		return attachmentController;
+	AttachmentRetriever getAttachmentRetriever() {
+		return attachmentRetriever;
 	}
 
 	LiveData<Contact> getContact() {
@@ -380,7 +348,7 @@ 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;
@@ -14,7 +15,6 @@ import org.briarproject.briar.api.forum.ForumInvitationRequest;
 import org.briarproject.briar.api.forum.ForumInvitationResponse;
 import org.briarproject.briar.api.introduction.IntroductionRequest;
 import org.briarproject.briar.api.introduction.IntroductionResponse;
-import org.briarproject.briar.api.messaging.AttachmentHeader;
 import org.briarproject.briar.api.messaging.PrivateMessageHeader;
 import org.briarproject.briar.api.privategroup.invitation.GroupInvitationRequest;
 import org.briarproject.briar.api.privategroup.invitation.GroupInvitationResponse;
@@ -55,8 +55,7 @@ class ConversationVisitor implements
 		if (h.getAttachmentHeaders().isEmpty()) {
 			attachments = emptyList();
 		} else {
-			attachments = attachmentCache
-					.getAttachmentItems(h.getId(), h.getAttachmentHeaders());
+			attachments = attachmentCache.getAttachmentItems(h);
 		}
 		if (h.isLocal()) {
 			item = new ConversationMessageItem(
@@ -294,7 +293,6 @@ class ConversationVisitor implements
 	}
 
 	interface AttachmentCache {
-		List<AttachmentItem> getAttachmentItems(MessageId m,
-				List<AttachmentHeader> headers);
+		List<AttachmentItem> getAttachmentItems(PrivateMessageHeader h);
 	}
 }

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

@@ -12,7 +12,7 @@ import org.briarproject.bramble.api.db.DatabaseExecutor;
 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;
@@ -134,10 +134,10 @@ public class ImageViewModel extends AndroidViewModel {
 
 	private void saveImage(AttachmentItem attachment, OutputStreamProvider osp,
 			@Nullable Runnable afterCopy) {
-		MessageId messageId = attachment.getMessageId();
 		dbExecutor.execute(() -> {
 			try {
-				Attachment a = messagingManager.getAttachment(messageId);
+				Attachment a =
+						messagingManager.getAttachment(attachment.getHeader());
 				copyImageFromDb(a, osp, afterCopy);
 			} catch (DbException e) {
 				logException(LOG, WARNING, e);

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

@@ -9,8 +9,8 @@ import com.bumptech.glide.load.data.DataFetcher;
 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.Attachment;
 import org.briarproject.briar.api.messaging.MessagingManager;
 
 import java.io.InputStream;
@@ -50,11 +50,12 @@ class BriarDataFetcher implements DataFetcher<InputStream> {
 	@Override
 	public void loadData(Priority priority,
 			DataCallback<? super InputStream> callback) {
-		MessageId id = attachment.getMessageId();
 		dbExecutor.execute(() -> {
 			if (cancel) return;
 			try {
-				inputStream = messagingManager.getAttachment(id).getStream();
+				Attachment a =
+						messagingManager.getAttachment(attachment.getHeader());
+				inputStream = a.getStream();
 				callback.onDataReady(inputStream);
 			} catch (DbException e) {
 				callback.onLoadFailed(e);

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.acra.model.Element;
+import org.briarproject.bramble.api.nullsafety.MethodsNotNullByDefault;
+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.logging.Level.WARNING;
+import static java.util.Objects.requireNonNull;
 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
-		implements CompoundButton.OnCheckedChangeListener {
-
-	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);
-	}
+@MethodsNotNullByDefault
+@ParametersNotNullByDefault
+public class DevReportActivity extends BaseCrashReportDialog {
 
 	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);
-		getDelegate().setSupportActionBar(tb);
+		Toolbar toolbar = findViewById(R.id.toolbar);
+		getDelegate().setSupportActionBar(toolbar);
 
-		View requestReport = findViewById(R.id.request_report);
-		View reportForm = findViewById(R.id.report_form);
-		userCommentView = findViewById(R.id.user_comment);
-		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);
+		String title = getString(isFeedback() ? R.string.feedback_title :
+				R.string.crash_report_title);
+		requireNonNull(getDelegate().getSupportActionBar()).setTitle(title);
 
-		//noinspection ConstantConditions
-		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);
+		if (state == null) displayFragment(isFeedback());
 	}
 
 	@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
-	public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
-		ReportField field = (ReportField) buttonView.getTag();
-		if (field != null) {
-			if (isChecked) excludedFields.remove(field);
-			else excludedFields.add(field);
-		}
+	void sendCrashReport(String comment, String email) {
+		sendCrash(comment, email);
 	}
 
-	@SuppressWarnings("ThrowableResultOfMethodCallIgnored")
 	private boolean isFeedback() {
 		return getException() instanceof UserFeedback;
 	}
 
-	private void refresh() {
-		report.setVisibility(INVISIBLE);
-		progress.setVisibility(VISIBLE);
-		report.removeAllViews();
-		new AsyncTask<Void, Void, CrashReportData>() {
+	void displayFragment(boolean showReportForm) {
+		Fragment f;
+		if (showReportForm) {
+			File file =
+					(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() {
-		userCommentView.setEnabled(false);
-		userEmailView.setEnabled(false);
-		sendReport.setEnabled(false);
-		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();
+	@Override
+	public void invalidateOptionsMenu() {
+		super.invalidateOptionsMenu();
+		getDelegate().invalidateOptionsMenu();
 	}
 
-	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();
-		requireNonNull(adapter).removeUri(uri);
+				((ImagePreviewAdapter) imageList.getAdapter());
+		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 ImagePreviewListener listener;
+	private final List<ImagePreviewItem> items;
 	@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 pos = items.indexOf(uri);
-		if (pos == -1) return;
-		items.remove(uri);
-		notifyItemRemoved(pos);
+	int loadItemPreview(AttachmentItemResult result) {
+		ImagePreviewItem newItem = new ImagePreviewItem(result.getUri());
+		int pos = items.indexOf(newItem);
+		if (pos == NO_POSITION) throw new AssertionError();
+		ImagePreviewItem item = items.get(pos);
+		if (item.getItem() == null) {
+			item.setItem(requireNonNull(result.getItem()));
+			notifyItemChanged(pos, item);
+			return pos;
+		}
+		return NO_POSITION;
 	}
 
 }