Create a new connection if a candidate reuses an address

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 837 matching lines @@
 
 // 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->SupportsProtocol(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.
+  // found or it is found but the existing remote candidate has an older
+  // generation, then we can create a new connection for this address.
   Connection* connection = port->GetConnection(remote_candidate.address());
-  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: "
-                << remote_candidate.ToString();
+  if (connection == nullptr ||
+      connection->remote_candidate().generation() <
+          remote_candidate.generation()) {
+    // Don't create a connection if this is a candidate we received in a
+    // message and we are not allowed to make outgoing connections.
+    PortInterface::CandidateOrigin origin = GetOrigin(port, origin_port);
+    if (origin == PortInterface::ORIGIN_MESSAGE && incoming_only_) {
       return false;
     }
-  } else {
-    PortInterface::CandidateOrigin origin = GetOrigin(port, origin_port);
-
-    // Don't create connection if this is a candidate we received in a
-    // message and we are not allowed to make outgoing connections.
-    if (origin == PortInterface::ORIGIN_MESSAGE && incoming_only_)
+    Connection* connection = port->CreateConnection(remote_candidate, origin);
+    if (!connection) {
       return false;
-
-    connection = port->CreateConnection(remote_candidate, origin);
-    if (!connection)
-      return false;
-
+    }
     AddConnection(connection);
-
     LOG_J(LS_INFO, this) << "Created connection with origin=" << origin << ", ("
                          << connections_.size() << " total)";
+    return true;
   }
 
-  return true;
+  // No new connection was created.
+  // Check if this is a peer reflexive candidate.
+  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: " << remote_candidate.ToString();
+  }
+  return false;
 }
 
 bool P2PTransportChannel::FindConnection(Connection* connection) const {
   std::vector<Connection*>::const_iterator citer =
       std::find(connections_.begin(), connections_.end(), connection);
   return citer != connections_.end();
 }
 
 uint32_t P2PTransportChannel::GetRemoteCandidateGeneration(
     const Candidate& candidate) {
@@ skipping 793 matching lines @@
 
   // During the initial state when nothing has been pinged yet, return the first
   // one in the ordered |connections_|.
   return *(std::find_if(connections_.begin(), connections_.end(),
                         [conn1, conn2](Connection* conn) {
                           return conn == conn1 || conn == conn2;
                         }));
 }
 
 }  // namespace cricket