Only add transport properties and keys when the contact was added

This will be changed once we have a way to reset state for peers
that were contacts already at some point in the past.
One contact might have deleted the other, but not vice versa.
So they have mismatching state that needs to be reset.

See #2 for more information.

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

@@ -419,23 +419,22 @@ class IntroduceeProtocolEngine
 				s.getRemote().acceptTimestamp);
 		if (timestamp == -1) throw new AssertionError();
 
-		boolean contactAdded = false;
+		Map<TransportId, KeySetId> keys = null;
 		try {
 			contactManager
 					.addContact(txn, s.getRemote().author, localAuthor.getId(),
 							false, true);
-			contactAdded = true;
+
-		} catch (ContactExistsException e) {
+			// Only add transport properties and keys when the contact was added
-			// Ignore this, because the other introducee might have deleted us.
+			// This will be changed once we have a way to reset state for peers
-			// So we still want updated transport properties
+			// that were contacts already at some point in the past.
-			// and new transport keys.
+			Contact c = contactManager
-		}
+					.getContact(txn, s.getRemote().author.getId(),
-		Contact c = contactManager.getContact(txn, s.getRemote().author.getId(),
 							localAuthor.getId());
 
-		// bind the keys to the new (or existing) contact
+			// bind the keys to the new contact
 			//noinspection ConstantConditions
-		Map<TransportId, KeySetId> keys = keyManager
+			keys = keyManager
 					.addUnboundKeys(txn, new SecretKey(s.getMasterKey()),
 							timestamp, s.getRemote().alice);
 			keyManager.bindKeys(txn, c.getId(), keys);
@@ -445,16 +444,19 @@ class IntroduceeProtocolEngine
 			transportPropertyManager.addRemoteProperties(txn, c.getId(),
 					s.getRemote().transportProperties);
 
-		// send ACTIVATE message with a MAC
-		byte[] mac = crypto.activateMac(s);
-		Message sent = sendActivateMessage(txn, s, getLocalTimestamp(s), mac);
-
-		if (contactAdded) {
 			// Broadcast IntroductionSucceededEvent, because contact got added
 			IntroductionSucceededEvent e = new IntroductionSucceededEvent(c);
 			txn.attach(e);
+		} catch (ContactExistsException e) {
+			// Ignore this, because the other introducee might have deleted us.
+			// So we still want updated transport properties
+			// and new transport keys.
 		}
 
+		// send ACTIVATE message with a MAC
+		byte[] mac = crypto.activateMac(s);
+		Message sent = sendActivateMessage(txn, s, getLocalTimestamp(s), mac);
+
 		// Move to AWAIT_ACTIVATE state and clear key material from session
 		return IntroduceeSession.awaitActivate(s, m, sent, keys);
 	}
@@ -469,12 +471,15 @@ class IntroduceeProtocolEngine
 		try {
 			crypto.verifyActivateMac(m.getMac(), s);
 		} catch (GeneralSecurityException e) {
-			// TODO remove transport keys?
 			return abort(txn, s);
 		}
 
+		// We might not have added transport keys
+		// if the contact existed when the remote AUTH was received.
+		if (s.getTransportKeys() != null) {
 			// Activate transport keys
 			keyManager.activateKeys(txn, s.getTransportKeys());
+		}
 
 		// Move back to START state
 		return IntroduceeSession.clear(s, START, s.getLastLocalMessageId(),