Only try to pair protocol matching candidates for creating connections.

webrtc/p2p/base/p2ptransportchannel.cc

 /*
  *  Copyright 2004 The WebRTC Project Authors. All rights reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 720 matching lines @@
   RememberRemoteCandidate(new_remote_candidate, origin_port);
 
   return created;
 }
 
 // Setup a connection object for the local and remote candidate combination.
 // And then listen to connection object for changes.
 bool P2PTransportChannel::CreateConnection(PortInterface* port,
                                            const Candidate& remote_candidate,
                                            PortInterface* origin_port) {
+  if (!port->ProtocolMatch(remote_candidate.protocol())) {
+    return false;
+  }
   // Look for an existing connection with this remote address.  If one is not
   // found, then we can create a new connection for this address.
   Connection* connection = port->GetConnection(remote_candidate.address());

[pthatcher1, 2015/12/11 02:05:36]

So, if we get two TURN candidates, one for TCP and one for UDP, both with the
same IP and port, what happens?  It's the same TurnPort, right?  So wouldn't
that case fail?  Would that mean we'd be back to making the map be based on (ip,
port, protocol)?  

[honghaiz3, 2015/12/11 18:36:31]

TurnPort should only generate UDP candidate. GTurnPort may handle both UDP and
TCP connections but that is deprecated, right?

[pthatcher1, 2015/12/12 03:05:30]

Oh, duh.  Good point.

   if (connection != NULL) {
     connection->MaybeUpdatePeerReflexiveCandidate(remote_candidate);
 
     // It is not legal to try to change any of the parameters of an existing
     // connection; however, the other side can send a duplicate candidate.
     if (!remote_candidate.IsEquivalent(connection->remote_candidate())) {
       LOG(INFO) << "Attempt to change a remote candidate."
                 << " Existing remote candidate: "
                 << connection->remote_candidate().ToString()
                 << "New remote candidate: "
@@ skipping 640 matching lines @@
   SignalSentPacket(this, sent_packet);
 }
 
 void P2PTransportChannel::OnReadyToSend(Connection* connection) {
   if (connection == best_connection_ && writable()) {
     SignalReadyToSend(this);
   }
 }
 
 }  // namespace cricket