Don't crash if STUN error message is missing ERROR-CODE attribute.

webrtc/p2p/base/port.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 1393 matching lines @@
   int64_t time_received = rtc::TimeMillis();
   packet_loss_estimator_.ReceivedResponse(request->id(), time_received);
 
   stats_.recv_ping_responses++;
 
   MaybeUpdateLocalCandidate(request, response);
 }
 
 void Connection::OnConnectionRequestErrorResponse(ConnectionRequest* request,
                                                   StunMessage* response) {
-  const StunErrorCodeAttribute* error_attr = response->GetErrorCode();
-  int error_code = STUN_ERROR_GLOBAL_FAILURE;
-  if (error_attr) {
-    error_code = error_attr->code();
-  }
-
+  int error_code = response->GetErrorCodeValue();
   LOG_J(LS_INFO, this) << "Received STUN error response"
                        << " id=" << rtc::hex_encode(request->id())
                        << " code=" << error_code
                        << " rtt=" << request->Elapsed();
 
   if (error_code == STUN_ERROR_UNKNOWN_ATTRIBUTE ||
       error_code == STUN_ERROR_SERVER_ERROR ||
       error_code == STUN_ERROR_UNAUTHORIZED) {
     // Recoverable error, retry
   } else if (error_code == STUN_ERROR_STALE_CREDENTIALS) {
@@ skipping 195 matching lines @@
     RTC_DCHECK(sent < 0);
     error_ = port_->GetError();
     stats_.sent_discarded_packets++;
   } else {
     send_rate_tracker_.AddSamples(sent);
   }
   return sent;
 }
 
 }  // namespace cricket