Do not allow session ID reuse and clean up sessions for introducee

It was possible that a malicious introducer sends new request with the
same session ID that was used previously and thus causing introducees to
have multiple states for the same session ID.
This commits prevents that from happening and adds an integration test
for that scenario.

Also if an introducee removes an introducer, all past session states
will be deleted from the database. For this, a test was added as well.

Closes #371
Closes #372

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

@@ -2,11 +2,17 @@ package org.briarproject;
 
 import net.jodah.concurrentunit.Waiter;
 
+import org.briarproject.api.clients.SessionId;
 import org.briarproject.api.contact.Contact;
 import org.briarproject.api.contact.ContactId;
 import org.briarproject.api.contact.ContactManager;
 import org.briarproject.api.crypto.SecretKey;
+import org.briarproject.api.data.BdfDictionary;
+import org.briarproject.api.data.BdfEntry;
+import org.briarproject.api.db.DatabaseComponent;
 import org.briarproject.api.db.DbException;
+import org.briarproject.api.db.Metadata;
+import org.briarproject.api.db.Transaction;
 import org.briarproject.api.event.Event;
 import org.briarproject.api.event.EventListener;
 import org.briarproject.api.event.IntroductionAbortedEvent;
@@ -18,17 +24,21 @@ import org.briarproject.api.identity.AuthorFactory;
 import org.briarproject.api.identity.IdentityManager;
 import org.briarproject.api.identity.LocalAuthor;
 import org.briarproject.api.introduction.IntroductionManager;
+import org.briarproject.api.introduction.IntroductionMessage;
 import org.briarproject.api.introduction.IntroductionRequest;
-import org.briarproject.api.clients.SessionId;
 import org.briarproject.api.lifecycle.LifecycleManager;
 import org.briarproject.api.properties.TransportProperties;
 import org.briarproject.api.properties.TransportPropertyManager;
+import org.briarproject.api.sync.Group;
+import org.briarproject.api.sync.MessageId;
 import org.briarproject.api.sync.SyncSession;
 import org.briarproject.api.sync.SyncSessionFactory;
 import org.briarproject.api.system.Clock;
 import org.briarproject.contact.ContactModule;
 import org.briarproject.crypto.CryptoModule;
+import org.briarproject.introduction.IntroductionGroupFactory;
 import org.briarproject.introduction.IntroductionModule;
+import org.briarproject.introduction.MessageSender;
 import org.briarproject.lifecycle.LifecycleModule;
 import org.briarproject.properties.PropertiesModule;
 import org.briarproject.sync.SyncModule;
@@ -41,7 +51,10 @@ import java.io.ByteArrayInputStream;
 import java.io.ByteArrayOutputStream;
 import java.io.File;
 import java.io.IOException;
+import java.util.ArrayList;
 import java.util.Collections;
+import java.util.List;
+import java.util.Map;
 import java.util.concurrent.TimeoutException;
 import java.util.logging.Logger;
 
@@ -50,6 +63,12 @@ import javax.inject.Inject;
 import static org.briarproject.TestPluginsModule.MAX_LATENCY;
 import static org.briarproject.TestPluginsModule.TRANSPORT_ID;
 import static org.briarproject.api.identity.AuthorConstants.MAX_PUBLIC_KEY_LENGTH;
+import static org.briarproject.api.introduction.IntroductionConstants.GROUP_ID;
+import static org.briarproject.api.introduction.IntroductionConstants.NAME;
+import static org.briarproject.api.introduction.IntroductionConstants.PUBLIC_KEY;
+import static org.briarproject.api.introduction.IntroductionConstants.SESSION_ID;
+import static org.briarproject.api.introduction.IntroductionConstants.TYPE;
+import static org.briarproject.api.introduction.IntroductionConstants.TYPE_REQUEST;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
@@ -629,6 +648,189 @@ public class IntroductionIntegrationTest extends BriarTestCase {
 		}
 	}
 
+	@Test
+	public void testSessionIdReuse() throws Exception {
+		startLifecycles();
+		try {
+			// Add Identities
+			addDefaultIdentities();
+
+			// Add Transport Properties
+			addTransportProperties();
+
+			// Add introducees as contacts
+			contactId1 = contactManager0.addContact(author1,
+					author0.getId(), master, clock.currentTimeMillis(), true,
+					true
+			);
+			contactId2 = contactManager0.addContact(author2,
+					author0.getId(), master, clock.currentTimeMillis(), true,
+					true
+			);
+			// Add introducer back
+			contactId0 = contactManager1.addContact(author0,
+					author1.getId(), master, clock.currentTimeMillis(), true,
+					true
+			);
+			ContactId contactId02 = contactManager2.addContact(author0,
+					author2.getId(), master, clock.currentTimeMillis(), true,
+					true
+			);
+			assertTrue(contactId0.equals(contactId02));
+
+			// listen to events
+			IntroducerListener listener0 = new IntroducerListener();
+			t0.getEventBus().addListener(listener0);
+			IntroduceeListener listener1 = new IntroduceeListener(1, true);
+			t1.getEventBus().addListener(listener1);
+			IntroduceeListener listener2 = new IntroduceeListener(2, true);
+			t2.getEventBus().addListener(listener2);
+
+			// make introduction
+			long time = clock.currentTimeMillis();
+			Contact introducee1 = contactManager0.getContact(contactId1);
+			Contact introducee2 = contactManager0.getContact(contactId2);
+			introductionManager0
+					.makeIntroduction(introducee1, introducee2, "Hi!", time);
+
+			// sync first request message
+			deliverMessage(sync0, contactId0, sync1, contactId1, "0 to 1");
+			eventWaiter.await(TIMEOUT, 1);
+			assertTrue(listener1.requestReceived);
+
+			// get SessionId
+			List<IntroductionMessage> list = new ArrayList<>(
+					introductionManager1.getIntroductionMessages(contactId0));
+			assertEquals(2, list.size());
+			assertTrue(list.get(0) instanceof IntroductionRequest);
+			IntroductionRequest msg = (IntroductionRequest) list.get(0);
+			SessionId sessionId = msg.getSessionId();
+
+			// get contact group
+			IntroductionGroupFactory groupFactory =
+					t0.getIntroductionGroupFactory();
+			Group group = groupFactory.createIntroductionGroup(introducee1);
+
+			// create new message with same SessionId
+			BdfDictionary d = BdfDictionary.of(
+					new BdfEntry(TYPE, TYPE_REQUEST),
+					new BdfEntry(SESSION_ID, sessionId),
+					new BdfEntry(GROUP_ID, group.getId()),
+					new BdfEntry(NAME, TestUtils.getRandomString(42)),
+					new BdfEntry(PUBLIC_KEY,
+							TestUtils.getRandomBytes(MAX_PUBLIC_KEY_LENGTH))
+			);
+
+			// reset request received state
+			listener1.requestReceived = false;
+
+			// add the message to the queue
+			DatabaseComponent db0 = t0.getDatabaseComponent();
+			MessageSender sender0 = t0.getMessageSender();
+			Transaction txn = db0.startTransaction(false);
+			try {
+				sender0.sendMessage(txn, d);
+				txn.setComplete();
+			} finally {
+				db0.endTransaction(txn);
+			}
+
+			// actually send message
+			deliverMessage(sync0, contactId0, sync1, contactId1, "0 to 1");
+
+			// make sure it does not arrive
+			assertFalse(listener1.requestReceived);
+		} finally {
+			stopLifecycles();
+		}
+	}
+
+	@Test
+	public void testIntroducerRemovedCleanup() throws Exception {
+		startLifecycles();
+		try {
+			// Add Identities
+			addDefaultIdentities();
+
+			// Add Transport Properties
+			addTransportProperties();
+
+			// Add introducees as contacts
+			contactId1 = contactManager0.addContact(author1,
+					author0.getId(), master, clock.currentTimeMillis(), true,
+					true
+			);
+			contactId2 = contactManager0.addContact(author2,
+					author0.getId(), master, clock.currentTimeMillis(), true,
+					true
+			);
+			// Add introducer back
+			contactId0 = contactManager1.addContact(author0,
+					author1.getId(), master, clock.currentTimeMillis(), true,
+					true
+			);
+			ContactId contactId02 = contactManager2.addContact(author0,
+					author2.getId(), master, clock.currentTimeMillis(), true,
+					true
+			);
+			assertTrue(contactId0.equals(contactId02));
+
+			// listen to events
+			IntroducerListener listener0 = new IntroducerListener();
+			t0.getEventBus().addListener(listener0);
+			IntroduceeListener listener1 = new IntroduceeListener(1, true);
+			t1.getEventBus().addListener(listener1);
+			IntroduceeListener listener2 = new IntroduceeListener(2, true);
+			t2.getEventBus().addListener(listener2);
+
+			// make introduction
+			long time = clock.currentTimeMillis();
+			Contact introducee1 = contactManager0.getContact(contactId1);
+			Contact introducee2 = contactManager0.getContact(contactId2);
+			introductionManager0
+					.makeIntroduction(introducee1, introducee2, "Hi!", time);
+
+			// sync first request message
+			deliverMessage(sync0, contactId0, sync1, contactId1, "0 to 1");
+			eventWaiter.await(TIMEOUT, 1);
+			assertTrue(listener1.requestReceived);
+
+			// get database and local group for introducee
+			DatabaseComponent db1 = t1.getDatabaseComponent();
+			IntroductionGroupFactory groupFactory1 =
+					t1.getIntroductionGroupFactory();
+			Group group1 = groupFactory1.createLocalGroup();
+
+			// get local session state messages
+			Map<MessageId, Metadata> map;
+			Transaction txn = db1.startTransaction(false);
+			try {
+				map = db1.getMessageMetadata(txn, group1.getId());
+				txn.setComplete();
+			} finally {
+				db1.endTransaction(txn);
+			}
+			// check that we have one session state
+			assertEquals(1, map.size());
+
+			// introducee1 removes introducer
+			contactManager1.removeContact(contactId0);
+
+			// get local session state messages again
+			txn = db1.startTransaction(false);
+			try {
+				map = db1.getMessageMetadata(txn, group1.getId());
+				txn.setComplete();
+			} finally {
+				db1.endTransaction(txn);
+			}
+			// make sure local state got deleted
+			assertEquals(0, map.size());
+		} finally {
+			stopLifecycles();
+		}
+	}
+
 	// TODO add a test for faking responses when #256 is implemented
 
 	@After

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

@@ -1,6 +1,7 @@
 package org.briarproject;
 
 import org.briarproject.api.contact.ContactManager;
+import org.briarproject.api.db.DatabaseComponent;
 import org.briarproject.api.event.EventBus;
 import org.briarproject.api.identity.IdentityManager;
 import org.briarproject.api.introduction.IntroductionManager;
@@ -14,7 +15,9 @@ import org.briarproject.data.DataModule;
 import org.briarproject.db.DatabaseModule;
 import org.briarproject.event.EventModule;
 import org.briarproject.identity.IdentityModule;
+import org.briarproject.introduction.IntroductionGroupFactory;
 import org.briarproject.introduction.IntroductionModule;
+import org.briarproject.introduction.MessageSender;
 import org.briarproject.lifecycle.LifecycleModule;
 import org.briarproject.properties.PropertiesModule;
 import org.briarproject.sync.SyncModule;
@@ -74,4 +77,12 @@ public interface IntroductionIntegrationTestComponent {
 
 	SyncSessionFactory getSyncSessionFactory();
 
+	/* the following methods are only needed to manually construct messages */
+
+	DatabaseComponent getDatabaseComponent();
+
+	MessageSender getMessageSender();
+
+	IntroductionGroupFactory getIntroductionGroupFactory();
+
 }

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

@@ -6,7 +6,7 @@ import org.briarproject.api.sync.Group;
 
 import javax.inject.Inject;
 
-class IntroductionGroupFactory {
+public class IntroductionGroupFactory {
 
 	final private PrivateGroupFactory privateGroupFactory;
 	final private Group localGroup;

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

@@ -147,8 +147,13 @@ class IntroductionManagerImpl extends BdfIncomingMessageHook
 			for (Map.Entry<MessageId, BdfDictionary> entry : map.entrySet()) {
 				BdfDictionary d = entry.getValue();
 				long role = d.getLong(ROLE, -1L);
-				if (role != ROLE_INTRODUCER) continue;
-				if (d.getLong(CONTACT_ID_1).equals(id) ||
+				if (role != ROLE_INTRODUCER) {
+					if (d.getLong(CONTACT_ID_1).equals(id)) {
+						// delete states if introducee removes introducer
+						deleteMessage(txn, entry.getKey());
+					}
+				}
+				else if (d.getLong(CONTACT_ID_1).equals(id) ||
 						d.getLong(CONTACT_ID_2).equals(id)) {
 
 					IntroducerProtocolState state = IntroducerProtocolState
@@ -178,13 +183,19 @@ class IntroductionManagerImpl extends BdfIncomingMessageHook
 
 		// Get message data and type
 		GroupId groupId = m.getGroupId();
-		message.put(GROUP_ID, groupId);
 		long type = message.getLong(TYPE, -1L);
 
 		// we are an introducee, need to initialize new state
 		if (type == TYPE_REQUEST) {
+			boolean stateExists = true;
+			try {
+				getSessionState(txn, groupId, message.getRaw(SESSION_ID), false);
+			} catch (FormatException e) {
+				stateExists = false;
+			}
 			BdfDictionary state;
 			try {
+				if (stateExists) throw new FormatException();
 				state = introduceeManager.initialize(txn, groupId, message);
 			} catch (FormatException e) {
 				if (LOG.isLoggable(WARNING)) {
@@ -450,7 +461,8 @@ class IntroductionManagerImpl extends BdfIncomingMessageHook
 	}
 
 	private BdfDictionary getSessionState(Transaction txn, GroupId groupId,
-			byte[] sessionId) throws DbException, FormatException {
+			byte[] sessionId, boolean warn)
+			throws DbException, FormatException {
 
 		try {
 			// See if we can find the state directly for the introducer
@@ -476,7 +488,7 @@ class IntroductionManagerImpl extends BdfIncomingMessageHook
 					if (g.equals(groupId)) return state;
 				}
 			}
-			if (LOG.isLoggable(WARNING)) {
+			if (warn && LOG.isLoggable(WARNING)) {
 				LOG.warning(
 						"No session state found for message with session ID " +
 								Arrays.hashCode(sessionId));
@@ -485,6 +497,12 @@ class IntroductionManagerImpl extends BdfIncomingMessageHook
 		}
 	}
 
+	private BdfDictionary getSessionState(Transaction txn, GroupId groupId,
+			byte[] sessionId) throws DbException, FormatException {
+
+		return getSessionState(txn, groupId, sessionId, true);
+	}
+
 	private void deleteMessage(Transaction txn, MessageId messageId)
 			throws DbException {
 

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

@@ -16,6 +16,7 @@ import static org.briarproject.api.identity.AuthorConstants.MAX_AUTHOR_NAME_LENG
 import static org.briarproject.api.identity.AuthorConstants.MAX_PUBLIC_KEY_LENGTH;
 import static org.briarproject.api.introduction.IntroductionConstants.ACCEPT;
 import static org.briarproject.api.introduction.IntroductionConstants.E_PUBLIC_KEY;
+import static org.briarproject.api.introduction.IntroductionConstants.GROUP_ID;
 import static org.briarproject.api.introduction.IntroductionConstants.MESSAGE_ID;
 import static org.briarproject.api.introduction.IntroductionConstants.MESSAGE_TIME;
 import static org.briarproject.api.introduction.IntroductionConstants.MSG;
@@ -63,6 +64,7 @@ class IntroductionValidator extends BdfMessageValidator {
 
 		d.put(TYPE, type);
 		d.put(SESSION_ID, id);
+		d.put(GROUP_ID, m.getGroupId());
 		d.put(MESSAGE_ID, m.getId());
 		d.put(MESSAGE_TIME, m.getTimestamp());
 		return d;

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

@@ -32,7 +32,7 @@ import static org.briarproject.api.introduction.IntroductionConstants.TYPE_ACK;
 import static org.briarproject.api.introduction.IntroductionConstants.TYPE_REQUEST;
 import static org.briarproject.api.introduction.IntroductionConstants.TYPE_RESPONSE;
 
-class MessageSender {
+public class MessageSender {
 
 	final private DatabaseComponent db;
 	final private ClientHelper clientHelper;