Mirror the remote auto-delete timer.

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

@@ -328,7 +328,8 @@ public class ConversationViewModel extends DbViewModel
 				return privateMessageFactory.createPrivateMessage(groupId,
 						timestamp, text, headers);
 			} else {
-				long timer = autoDeleteManager.getAutoDeleteTimer(txn, c);
+				long timer = autoDeleteManager.getAutoDeleteTimer(txn, c,
+						timestamp);
 				return privateMessageFactory.createPrivateMessage(groupId,
 						timestamp, text, headers, timer);
 			}

briar-android/src/main/java/org/briarproject/briar/android/privategroup/creation/CreateGroupControllerImpl.java

@@ -173,7 +173,8 @@ class CreateGroupControllerImpl extends ContactSelectorControllerImpl
 				Contact contact = contactManager.getContact(txn, c);
 				long timestamp = conversationManager
 						.getTimestampForOutgoingMessage(txn, c);
-				long timer = autoDeleteManager.getAutoDeleteTimer(txn, c);
+				long timer = autoDeleteManager.getAutoDeleteTimer(txn, c,
+						timestamp);
 				contexts.add(new InvitationContext(contact, timestamp, timer));
 			} catch (NoSuchContactException e) {
 				// Continue

briar-api/src/main/java/org/briarproject/briar/api/autodelete/AutoDeleteManager.java

@@ -24,8 +24,26 @@ public interface AutoDeleteManager {
 	 */
 	int MINOR_VERSION = 0;
 
-	long getAutoDeleteTimer(Transaction txn, ContactId c) throws DbException;
+	/**
+	 * Returns the auto-delete timer duration for the given contact, for use in
+	 * a message with the given timestamp. The timestamp is stored.
+	 */
+	long getAutoDeleteTimer(Transaction txn, ContactId c, long timestamp)
+			throws DbException;
 
+	/**
+	 * Sets the auto-delete timer duration for the given contact.
+	 */
 	void setAutoDeleteTimer(Transaction txn, ContactId c, long timer)
 			throws DbException;
+
+	/**
+	 * Receives an auto-delete timer duration from the given contact, carried
+	 * in a message with the given timestamp. The local timer is set to the
+	 * same duration unless it has been
+	 * {@link #setAutoDeleteTimer(Transaction, ContactId, long) changed} more
+	 * recently than the remote timer.
+	 */
+	void receiveAutoDeleteTimer(Transaction txn, ContactId c, long timer,
+			long timestamp) throws DbException;
 }

briar-core/src/main/java/org/briarproject/briar/autodelete/AutoDeleteConstants.java

@@ -2,6 +2,28 @@ package org.briarproject.briar.autodelete;
 
 interface AutoDeleteConstants {
 
-	// Group metadata key for storing the auto-delete timer
-	String GROUP_KEY_AUTO_DELETE_TIMER = "autoDeleteTimer";
+	/**
+	 * Group metadata key for storing the auto-delete timer duration.
+	 */
+	String GROUP_KEY_TIMER = "autoDeleteTimer";
+
+	/**
+	 * Group metadata key for storing the timestamp of the latest incoming or
+	 * outgoing message carrying an auto-delete timer (including a null timer).
+	 */
+	String GROUP_KEY_TIMESTAMP = "autoDeleteTimestamp";
+
+	/**
+	 * Group metadata key for storing the previous auto-delete timer duration.
+	 * This is used to decide whether a local change to the duration should be
+	 * overwritten by a duration received from the contact.
+	 */
+	String GROUP_KEY_PREVIOUS_TIMER = "autoDeletePreviousTimer";
+
+	/**
+	 * Special value for {@link #GROUP_KEY_PREVIOUS_TIMER} indicating that
+	 * there are no local changes to the auto-delete timer duration that need
+	 * to be compared with durations received from the contact.
+	 */
+	long NO_PREVIOUS_TIMER = 0;
 }

briar-core/src/main/java/org/briarproject/briar/autodelete/AutoDeleteManagerImpl.java

@@ -17,19 +17,29 @@ import org.briarproject.bramble.api.sync.Group;
 import org.briarproject.bramble.api.sync.GroupFactory;
 import org.briarproject.briar.api.autodelete.AutoDeleteManager;
 
+import java.util.logging.Logger;
+
 import javax.annotation.concurrent.Immutable;
 import javax.inject.Inject;
 
+import static java.util.logging.Level.INFO;
+import static java.util.logging.Logger.getLogger;
 import static org.briarproject.briar.api.autodelete.AutoDeleteConstants.MAX_AUTO_DELETE_TIMER_MS;
 import static org.briarproject.briar.api.autodelete.AutoDeleteConstants.MIN_AUTO_DELETE_TIMER_MS;
 import static org.briarproject.briar.api.autodelete.AutoDeleteConstants.NO_AUTO_DELETE_TIMER;
-import static org.briarproject.briar.autodelete.AutoDeleteConstants.GROUP_KEY_AUTO_DELETE_TIMER;
+import static org.briarproject.briar.autodelete.AutoDeleteConstants.GROUP_KEY_PREVIOUS_TIMER;
+import static org.briarproject.briar.autodelete.AutoDeleteConstants.GROUP_KEY_TIMER;
+import static org.briarproject.briar.autodelete.AutoDeleteConstants.GROUP_KEY_TIMESTAMP;
+import static org.briarproject.briar.autodelete.AutoDeleteConstants.NO_PREVIOUS_TIMER;
 
 @Immutable
 @NotNullByDefault
 class AutoDeleteManagerImpl
 		implements AutoDeleteManager, OpenDatabaseHook, ContactHook {
 
+	private static final Logger LOG =
+			getLogger(AutoDeleteManagerImpl.class.getName());
+
 	private final DatabaseComponent db;
 	private final ClientHelper clientHelper;
 	private final GroupFactory groupFactory;
@@ -69,14 +79,22 @@ class AutoDeleteManagerImpl
 	}
 
 	@Override
-	public long getAutoDeleteTimer(Transaction txn, ContactId c)
+	public long getAutoDeleteTimer(Transaction txn, ContactId c, long timestamp)
 			throws DbException {
 		try {
 			Group g = getGroup(db.getContact(txn, c));
 			BdfDictionary meta =
 					clientHelper.getGroupMetadataAsDictionary(txn, g.getId());
-			return meta.getLong(GROUP_KEY_AUTO_DELETE_TIMER,
-					NO_AUTO_DELETE_TIMER);
+			long timer = meta.getLong(GROUP_KEY_TIMER, NO_AUTO_DELETE_TIMER);
+			if (LOG.isLoggable(INFO)) {
+				LOG.info("Sending message with auto-delete timer " + timer);
+			}
+			// Update the timestamp and clear the previous timer, if any
+			meta = BdfDictionary.of(
+					new BdfEntry(GROUP_KEY_TIMESTAMP, timestamp),
+					new BdfEntry(GROUP_KEY_PREVIOUS_TIMER, NO_PREVIOUS_TIMER));
+			clientHelper.mergeGroupMetadata(txn, g.getId(), meta);
+			return timer;
 		} catch (FormatException e) {
 			throw new DbException(e);
 		}
@@ -85,18 +103,60 @@ class AutoDeleteManagerImpl
 	@Override
 	public void setAutoDeleteTimer(Transaction txn, ContactId c, long timer)
 			throws DbException {
-		if (timer != NO_AUTO_DELETE_TIMER &&
-				(timer < MIN_AUTO_DELETE_TIMER_MS ||
-						timer > MAX_AUTO_DELETE_TIMER_MS)) {
-			throw new IllegalArgumentException();
-		}
+		validateTimer(timer);
 		try {
 			Group g = getGroup(db.getContact(txn, c));
-			BdfDictionary meta = BdfDictionary.of(
-					new BdfEntry(GROUP_KEY_AUTO_DELETE_TIMER, timer));
+			BdfDictionary meta =
+					clientHelper.getGroupMetadataAsDictionary(txn, g.getId());
+			long oldTimer = meta.getLong(GROUP_KEY_TIMER, NO_AUTO_DELETE_TIMER);
+			if (timer == oldTimer) return;
+			if (LOG.isLoggable(INFO)) {
+				LOG.info("Setting auto-delete timer to " + timer);
+			}
+			// Store the new timer and the previous timer
+			meta = BdfDictionary.of(
+					new BdfEntry(GROUP_KEY_TIMER, timer),
+					new BdfEntry(GROUP_KEY_PREVIOUS_TIMER, oldTimer));
 			clientHelper.mergeGroupMetadata(txn, g.getId(), meta);
 		} catch (FormatException e) {
-			throw new AssertionError(e);
+			throw new DbException(e);
+		}
+	}
+
+	@Override
+	public void receiveAutoDeleteTimer(Transaction txn, ContactId c,
+			long timer, long timestamp) throws DbException {
+		validateTimer(timer);
+		try {
+			Group g = getGroup(db.getContact(txn, c));
+			BdfDictionary meta =
+					clientHelper.getGroupMetadataAsDictionary(txn, g.getId());
+			long oldTimestamp = meta.getLong(GROUP_KEY_TIMESTAMP, 0L);
+			if (timestamp <= oldTimestamp) return;
+			long oldTimer =
+					meta.getLong(GROUP_KEY_PREVIOUS_TIMER, NO_PREVIOUS_TIMER);
+			meta = new BdfDictionary();
+			if (oldTimer == NO_PREVIOUS_TIMER) {
+				// We don't have an unsent change. Mirror their timer
+				if (LOG.isLoggable(INFO)) {
+					LOG.info("Mirroring auto-delete timer " + timer);
+				}
+				meta.put(GROUP_KEY_TIMER, timer);
+			} else if (timer != oldTimer) {
+				// Their sent change trumps our unsent change. Mirror their
+				// timer and clear the previous timer to drop our unsent change
+				if (LOG.isLoggable(INFO)) {
+					LOG.info("Mirroring auto-delete timer " + timer
+							+ " and forgetting unsent change");
+				}
+				meta.put(GROUP_KEY_TIMER, timer);
+				meta.put(GROUP_KEY_PREVIOUS_TIMER, NO_PREVIOUS_TIMER);
+			}
+			// Always update the timestamp
+			meta.put(GROUP_KEY_TIMESTAMP, timestamp);
+			clientHelper.mergeGroupMetadata(txn, g.getId(), meta);
+		} catch (FormatException e) {
+			throw new DbException(e);
 		}
 	}
 
@@ -104,4 +164,12 @@ class AutoDeleteManagerImpl
 		byte[] descriptor = c.getAuthor().getId().getBytes();
 		return groupFactory.createGroup(CLIENT_ID, MAJOR_VERSION, descriptor);
 	}
+
+	private void validateTimer(long timer) {
+		if (timer != NO_AUTO_DELETE_TIMER &&
+				(timer < MIN_AUTO_DELETE_TIMER_MS ||
+						timer > MAX_AUTO_DELETE_TIMER_MS)) {
+			throw new IllegalArgumentException();
+		}
+	}
 }

briar-core/src/main/java/org/briarproject/briar/introduction/AbstractProtocolEngine.java

@@ -100,7 +100,8 @@ abstract class AbstractProtocolEngine<S extends Session<?>>
 		Message m;
 		ContactId c = getContactId(txn, s.getContactGroupId());
 		if (contactSupportsAutoDeletion(txn, c)) {
-			long timer = autoDeleteManager.getAutoDeleteTimer(txn, c);
+			long timer = autoDeleteManager.getAutoDeleteTimer(txn, c,
+					timestamp);
 			m = messageEncoder.encodeRequestMessage(s.getContactGroupId(),
 					timestamp, s.getLastLocalMessageId(), author, text, timer);
 			sendMessage(txn, REQUEST, s.getSessionId(), m, true, timer);
@@ -120,7 +121,8 @@ abstract class AbstractProtocolEngine<S extends Session<?>>
 		Message m;
 		ContactId c = getContactId(txn, s.getContactGroupId());
 		if (contactSupportsAutoDeletion(txn, c)) {
-			long timer = autoDeleteManager.getAutoDeleteTimer(txn, c);
+			long timer = autoDeleteManager.getAutoDeleteTimer(txn, c,
+					timestamp);
 			m = messageEncoder.encodeAcceptMessage(s.getContactGroupId(),
 					timestamp, s.getLastLocalMessageId(), s.getSessionId(),
 					ephemeralPublicKey, acceptTimestamp, transportProperties,
@@ -141,7 +143,8 @@ abstract class AbstractProtocolEngine<S extends Session<?>>
 		Message m;
 		ContactId c = getContactId(txn, s.getContactGroupId());
 		if (contactSupportsAutoDeletion(txn, c)) {
-			long timer = autoDeleteManager.getAutoDeleteTimer(txn, c);
+			long timer = autoDeleteManager.getAutoDeleteTimer(txn, c,
+					timestamp);
 			m = messageEncoder.encodeDeclineMessage(s.getContactGroupId(),
 					timestamp, s.getLastLocalMessageId(), s.getSessionId(),
 					timer);

briar-core/src/main/java/org/briarproject/briar/privategroup/invitation/AbstractProtocolEngine.java

@@ -152,9 +152,11 @@ abstract class AbstractProtocolEngine<S extends Session<?>>
 		ContactId c = getContactId(txn, s.getContactGroupId());
 		if (contactSupportsAutoDeletion(txn, c)) {
 			// Set auto-delete timer if manually accepting an invitation
-			long timer = visibleInUi
-					? autoDeleteManager.getAutoDeleteTimer(txn, c)
-					: NO_AUTO_DELETE_TIMER;
+			long timer = NO_AUTO_DELETE_TIMER;
+			if (visibleInUi) {
+				timer = autoDeleteManager
+						.getAutoDeleteTimer(txn, c, localTimestamp);
+			}
 			m = messageEncoder.encodeJoinMessage(s.getContactGroupId(),
 					s.getPrivateGroupId(), localTimestamp,
 					s.getLastLocalMessageId(), timer);
@@ -179,9 +181,11 @@ abstract class AbstractProtocolEngine<S extends Session<?>>
 		ContactId c = getContactId(txn, s.getContactGroupId());
 		if (contactSupportsAutoDeletion(txn, c)) {
 			// Set auto-delete timer if manually accepting an invitation
-			long timer = visibleInUi
-					? autoDeleteManager.getAutoDeleteTimer(txn, c)
-					: NO_AUTO_DELETE_TIMER;
+			long timer = NO_AUTO_DELETE_TIMER;
+			if (visibleInUi) {
+				timer = autoDeleteManager.getAutoDeleteTimer(txn, c,
+						localTimestamp);
+			}
 			m = messageEncoder.encodeLeaveMessage(s.getContactGroupId(),
 					s.getPrivateGroupId(), localTimestamp,
 					s.getLastLocalMessageId(), timer);

briar-core/src/main/java/org/briarproject/briar/sharing/ProtocolEngineImpl.java

@@ -142,7 +142,8 @@ abstract class ProtocolEngineImpl<S extends Shareable>
 		long localTimestamp = getTimestampForVisibleMessage(txn, s);
 		ContactId c = getContactId(txn, s.getContactGroupId());
 		if (contactSupportsAutoDeletion(txn, c)) {
-			long timer = autoDeleteManager.getAutoDeleteTimer(txn, c);
+			long timer = autoDeleteManager.getAutoDeleteTimer(txn, c,
+					localTimestamp);
 			m = messageEncoder.encodeInviteMessage(s.getContactGroupId(),
 					localTimestamp, s.getLastLocalMessageId(), descriptor,
 					text, timer);
@@ -209,7 +210,8 @@ abstract class ProtocolEngineImpl<S extends Shareable>
 		long localTimestamp = getTimestampForVisibleMessage(txn, s);
 		ContactId c = getContactId(txn, s.getContactGroupId());
 		if (contactSupportsAutoDeletion(txn, c)) {
-			long timer = autoDeleteManager.getAutoDeleteTimer(txn, c);
+			long timer = autoDeleteManager.getAutoDeleteTimer(txn, c,
+					localTimestamp);
 			m = messageEncoder.encodeAcceptMessage(s.getContactGroupId(),
 					s.getShareableId(), localTimestamp,
 					s.getLastLocalMessageId(), timer);
@@ -263,7 +265,8 @@ abstract class ProtocolEngineImpl<S extends Shareable>
 		long localTimestamp = getTimestampForVisibleMessage(txn, s);
 		ContactId c = getContactId(txn, s.getContactGroupId());
 		if (contactSupportsAutoDeletion(txn, c)) {
-			long timer = autoDeleteManager.getAutoDeleteTimer(txn, c);
+			long timer = autoDeleteManager.getAutoDeleteTimer(txn, c,
+					localTimestamp);
 			m = messageEncoder.encodeDeclineMessage(s.getContactGroupId(),
 					s.getShareableId(), localTimestamp,
 					s.getLastLocalMessageId(), timer);

briar-core/src/test/java/org/briarproject/briar/autodelete/AutoDeleteManagerImplTest.java

@@ -18,12 +18,18 @@ import static org.briarproject.bramble.api.client.ContactGroupConstants.GROUP_KE
 import static org.briarproject.bramble.test.TestUtils.getContact;
 import static org.briarproject.bramble.test.TestUtils.getGroup;
 import static org.briarproject.briar.api.autodelete.AutoDeleteConstants.MAX_AUTO_DELETE_TIMER_MS;
+import static org.briarproject.briar.api.autodelete.AutoDeleteConstants.MIN_AUTO_DELETE_TIMER_MS;
 import static org.briarproject.briar.api.autodelete.AutoDeleteConstants.NO_AUTO_DELETE_TIMER;
 import static org.briarproject.briar.api.autodelete.AutoDeleteManager.CLIENT_ID;
 import static org.briarproject.briar.api.autodelete.AutoDeleteManager.MAJOR_VERSION;
-import static org.briarproject.briar.autodelete.AutoDeleteConstants.GROUP_KEY_AUTO_DELETE_TIMER;
+import static org.briarproject.briar.autodelete.AutoDeleteConstants.GROUP_KEY_PREVIOUS_TIMER;
+import static org.briarproject.briar.autodelete.AutoDeleteConstants.GROUP_KEY_TIMER;
+import static org.briarproject.briar.autodelete.AutoDeleteConstants.GROUP_KEY_TIMESTAMP;
+import static org.briarproject.briar.autodelete.AutoDeleteConstants.NO_PREVIOUS_TIMER;
 import static org.junit.Assert.assertEquals;
 
+// Thank you, I'm using them for readability
+@SuppressWarnings("UnnecessaryLocalVariable")
 public class AutoDeleteManagerImplTest extends BrambleMockTestCase {
 
 	private final DatabaseComponent db = context.mock(DatabaseComponent.class);
@@ -35,6 +41,7 @@ public class AutoDeleteManagerImplTest extends BrambleMockTestCase {
 	private final Group localGroup = getGroup(CLIENT_ID, MAJOR_VERSION);
 	private final Group contactGroup = getGroup(CLIENT_ID, MAJOR_VERSION);
 	private final Contact contact = getContact();
+	private final long now = System.currentTimeMillis();
 
 	private final AutoDeleteManagerImpl autoDeleteManager;
 
@@ -113,15 +120,44 @@ public class AutoDeleteManagerImplTest extends BrambleMockTestCase {
 	@Test
 	public void testStoresTimer() throws Exception {
 		Transaction txn = new Transaction(null, false);
-		long timer = MAX_AUTO_DELETE_TIMER_MS;
-		BdfDictionary meta = BdfDictionary.of(
-				new BdfEntry(GROUP_KEY_AUTO_DELETE_TIMER, timer));
+		long oldTimer = MIN_AUTO_DELETE_TIMER_MS;
+		long newTimer = MAX_AUTO_DELETE_TIMER_MS;
+		BdfDictionary oldMeta = BdfDictionary.of(
+				new BdfEntry(GROUP_KEY_TIMER, oldTimer),
+				new BdfEntry(GROUP_KEY_PREVIOUS_TIMER, NO_PREVIOUS_TIMER),
+				new BdfEntry(GROUP_KEY_TIMESTAMP, now));
+		BdfDictionary newMeta = BdfDictionary.of(
+				new BdfEntry(GROUP_KEY_TIMER, newTimer),
+				new BdfEntry(GROUP_KEY_PREVIOUS_TIMER, oldTimer));
 
 		expectGetContact(txn);
 		expectGetContactGroup();
 		context.checking(new Expectations() {{
+			oneOf(clientHelper).getGroupMetadataAsDictionary(txn,
+					contactGroup.getId());
+			will(returnValue(oldMeta));
 			oneOf(clientHelper).mergeGroupMetadata(txn,
-					contactGroup.getId(), meta);
+					contactGroup.getId(), newMeta);
+		}});
+
+		autoDeleteManager.setAutoDeleteTimer(txn, contact.getId(), newTimer);
+	}
+
+	@Test
+	public void testDoesNotStoreTimerIfUnchanged() throws Exception {
+		Transaction txn = new Transaction(null, false);
+		long timer = MAX_AUTO_DELETE_TIMER_MS;
+		BdfDictionary meta = BdfDictionary.of(
+				new BdfEntry(GROUP_KEY_TIMER, timer),
+				new BdfEntry(GROUP_KEY_PREVIOUS_TIMER, NO_PREVIOUS_TIMER),
+				new BdfEntry(GROUP_KEY_TIMESTAMP, now));
+
+		expectGetContact(txn);
+		expectGetContactGroup();
+		context.checking(new Expectations() {{
+			oneOf(clientHelper).getGroupMetadataAsDictionary(txn,
+					contactGroup.getId());
+			will(returnValue(meta));
 		}});
 
 		autoDeleteManager.setAutoDeleteTimer(txn, contact.getId(), timer);
@@ -133,7 +169,10 @@ public class AutoDeleteManagerImplTest extends BrambleMockTestCase {
 		long timer = MAX_AUTO_DELETE_TIMER_MS;
 		BdfDictionary meta = BdfDictionary.of(
 				new BdfEntry(GROUP_KEY_CONTACT_ID, contact.getId().getInt()),
-				new BdfEntry(GROUP_KEY_AUTO_DELETE_TIMER, timer));
+				new BdfEntry(GROUP_KEY_TIMER, timer));
+		BdfDictionary newMeta = BdfDictionary.of(
+				new BdfEntry(GROUP_KEY_TIMESTAMP, now),
+				new BdfEntry(GROUP_KEY_PREVIOUS_TIMER, NO_PREVIOUS_TIMER));
 
 		expectGetContact(txn);
 		expectGetContactGroup();
@@ -141,10 +180,12 @@ public class AutoDeleteManagerImplTest extends BrambleMockTestCase {
 			oneOf(clientHelper).getGroupMetadataAsDictionary(txn,
 					contactGroup.getId());
 			will(returnValue(meta));
+			oneOf(clientHelper).mergeGroupMetadata(txn, contactGroup.getId(),
+					newMeta);
 		}});
 
-		assertEquals(timer,
-				autoDeleteManager.getAutoDeleteTimer(txn, contact.getId()));
+		assertEquals(timer, autoDeleteManager
+				.getAutoDeleteTimer(txn, contact.getId(), now));
 	}
 
 	@Test
@@ -152,6 +193,44 @@ public class AutoDeleteManagerImplTest extends BrambleMockTestCase {
 		Transaction txn = new Transaction(null, false);
 		BdfDictionary meta = BdfDictionary.of(
 				new BdfEntry(GROUP_KEY_CONTACT_ID, contact.getId().getInt()));
+		BdfDictionary newMeta = BdfDictionary.of(
+				new BdfEntry(GROUP_KEY_TIMESTAMP, now),
+				new BdfEntry(GROUP_KEY_PREVIOUS_TIMER, NO_PREVIOUS_TIMER));
+
+		expectGetContact(txn);
+		expectGetContactGroup();
+		context.checking(new Expectations() {{
+			oneOf(clientHelper).getGroupMetadataAsDictionary(txn,
+					contactGroup.getId());
+			will(returnValue(meta));
+			oneOf(clientHelper).mergeGroupMetadata(txn, contactGroup.getId(),
+					newMeta);
+		}});
+
+		assertEquals(NO_AUTO_DELETE_TIMER, autoDeleteManager
+				.getAutoDeleteTimer(txn, contact.getId(), now));
+	}
+
+	@Test
+	public void testIgnoresReceivedTimerWithEarlierTimestamp()
+			throws Exception {
+		testIgnoresReceivedTimerWithTimestamp(now - 1);
+	}
+
+	@Test
+	public void testIgnoresReceivedTimerWithEqualTimestamp() throws Exception {
+		testIgnoresReceivedTimerWithTimestamp(now);
+	}
+
+	private void testIgnoresReceivedTimerWithTimestamp(long remoteTimestamp)
+			throws Exception {
+		Transaction txn = new Transaction(null, false);
+		long localTimer = MIN_AUTO_DELETE_TIMER_MS;
+		long remoteTimer = MAX_AUTO_DELETE_TIMER_MS;
+		BdfDictionary meta = BdfDictionary.of(
+				new BdfEntry(GROUP_KEY_TIMER, localTimer),
+				new BdfEntry(GROUP_KEY_PREVIOUS_TIMER, NO_PREVIOUS_TIMER),
+				new BdfEntry(GROUP_KEY_TIMESTAMP, now));
 
 		expectGetContact(txn);
 		expectGetContactGroup();
@@ -161,8 +240,99 @@ public class AutoDeleteManagerImplTest extends BrambleMockTestCase {
 			will(returnValue(meta));
 		}});
 
-		assertEquals(NO_AUTO_DELETE_TIMER,
-				autoDeleteManager.getAutoDeleteTimer(txn, contact.getId()));
+		autoDeleteManager.receiveAutoDeleteTimer(txn, contact.getId(),
+				remoteTimer, remoteTimestamp);
+	}
+
+	@Test
+	public void testMirrorsRemoteTimestampIfNoUnsentChange() throws Exception {
+		Transaction txn = new Transaction(null, false);
+		long localTimer = MIN_AUTO_DELETE_TIMER_MS;
+		long remoteTimer = MAX_AUTO_DELETE_TIMER_MS;
+		long remoteTimestamp = now + 1;
+		BdfDictionary oldMeta = BdfDictionary.of(
+				new BdfEntry(GROUP_KEY_TIMER, localTimer),
+				new BdfEntry(GROUP_KEY_PREVIOUS_TIMER, NO_PREVIOUS_TIMER),
+				new BdfEntry(GROUP_KEY_TIMESTAMP, now));
+		// The timestamp should be updated and the timer should be mirrored
+		BdfDictionary newMeta = BdfDictionary.of(
+				new BdfEntry(GROUP_KEY_TIMESTAMP, remoteTimestamp),
+				new BdfEntry(GROUP_KEY_TIMER, remoteTimer));
+
+		expectGetContact(txn);
+		expectGetContactGroup();
+		context.checking(new Expectations() {{
+			oneOf(clientHelper).getGroupMetadataAsDictionary(txn,
+					contactGroup.getId());
+			will(returnValue(oldMeta));
+			oneOf(clientHelper).mergeGroupMetadata(txn,
+					contactGroup.getId(), newMeta);
+		}});
+
+		autoDeleteManager.receiveAutoDeleteTimer(txn, contact.getId(),
+				remoteTimer, remoteTimestamp);
+	}
+
+	@Test
+	public void testDoesNotMirrorUnchangedRemoteTimestampIfUnsentChange()
+			throws Exception {
+		Transaction txn = new Transaction(null, false);
+		long localTimer = MIN_AUTO_DELETE_TIMER_MS;
+		long remoteTimer = MAX_AUTO_DELETE_TIMER_MS;
+		long remoteTimestamp = now + 1;
+		BdfDictionary oldMeta = BdfDictionary.of(
+				new BdfEntry(GROUP_KEY_TIMER, localTimer),
+				new BdfEntry(GROUP_KEY_PREVIOUS_TIMER, remoteTimer),
+				new BdfEntry(GROUP_KEY_TIMESTAMP, now));
+		// The timestamp should be updated but the timer should not revert
+		BdfDictionary newMeta = BdfDictionary.of(
+				new BdfEntry(GROUP_KEY_TIMESTAMP, remoteTimestamp));
+
+		expectGetContact(txn);
+		expectGetContactGroup();
+		context.checking(new Expectations() {{
+			oneOf(clientHelper).getGroupMetadataAsDictionary(txn,
+					contactGroup.getId());
+			will(returnValue(oldMeta));
+			oneOf(clientHelper).mergeGroupMetadata(txn,
+					contactGroup.getId(), newMeta);
+		}});
+
+		autoDeleteManager.receiveAutoDeleteTimer(txn, contact.getId(),
+				remoteTimer, remoteTimestamp);
+	}
+
+	@Test
+	public void testMirrorsChangedRemoteTimestampIfUnsentChange()
+			throws Exception {
+		Transaction txn = new Transaction(null, false);
+		long localTimer = MIN_AUTO_DELETE_TIMER_MS;
+		long oldRemoteTimer = MAX_AUTO_DELETE_TIMER_MS;
+		long newRemoteTimer = MAX_AUTO_DELETE_TIMER_MS - 1;
+		long remoteTimestamp = now + 1;
+		BdfDictionary oldMeta = BdfDictionary.of(
+				new BdfEntry(GROUP_KEY_TIMER, localTimer),
+				new BdfEntry(GROUP_KEY_PREVIOUS_TIMER, oldRemoteTimer),
+				new BdfEntry(GROUP_KEY_TIMESTAMP, now));
+		// The timestamp should be updated , the timer should be mirrored and
+		// the previous timer should be cleared
+		BdfDictionary newMeta = BdfDictionary.of(
+				new BdfEntry(GROUP_KEY_TIMESTAMP, remoteTimestamp),
+				new BdfEntry(GROUP_KEY_TIMER, newRemoteTimer),
+				new BdfEntry(GROUP_KEY_PREVIOUS_TIMER, NO_PREVIOUS_TIMER));
+
+		expectGetContact(txn);
+		expectGetContactGroup();
+		context.checking(new Expectations() {{
+			oneOf(clientHelper).getGroupMetadataAsDictionary(txn,
+					contactGroup.getId());
+			will(returnValue(oldMeta));
+			oneOf(clientHelper).mergeGroupMetadata(txn,
+					contactGroup.getId(), newMeta);
+		}});
+
+		autoDeleteManager.receiveAutoDeleteTimer(txn, contact.getId(),
+				newRemoteTimer, remoteTimestamp);
 	}
 
 	private void expectGetContact(Transaction txn) throws Exception {

briar-core/src/test/java/org/briarproject/briar/privategroup/invitation/AbstractProtocolEngineTest.java

@@ -256,7 +256,8 @@ abstract class AbstractProtocolEngineTest extends BrambleMockTestCase {
 
 	void expectGetAutoDeleteTimer() throws Exception {
 		context.checking(new Expectations() {{
-			oneOf(autoDeleteManager).getAutoDeleteTimer(txn, contactId);
+			oneOf(autoDeleteManager).getAutoDeleteTimer(txn, contactId,
+					localTimestamp);
 			will(returnValue(NO_AUTO_DELETE_TIMER));
 		}});
 	}