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

webrtc/p2p/base/stun.h

 /*
  *  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 138 matching lines @@
   bool SetTransactionID(const std::string& str);
 
   // Gets the desired attribute value, or NULL if no such attribute type exists.
   const StunAddressAttribute* GetAddress(int type) const;
   const StunUInt32Attribute* GetUInt32(int type) const;
   const StunUInt64Attribute* GetUInt64(int type) const;
   const StunByteStringAttribute* GetByteString(int type) const;
 
   // Gets these specific attribute values.
   const StunErrorCodeAttribute* GetErrorCode() const;
+  // Returns the code inside the error code attribute, if present, and
+  // STUN_ERROR_GLOBAL_FAILURE otherwise.
+  int GetErrorCodeValue() const;
   const StunUInt16ListAttribute* GetUnknownAttributes() const;
 
   // Takes ownership of the specified attribute and adds it to the message.
   void AddAttribute(std::unique_ptr<StunAttribute> attr);
 
   // Validates that a raw STUN message has a correct MESSAGE-INTEGRITY value.
   // This can't currently be done on a StunMessage, since it is affected by
   // padding data (which we discard when reading a StunMessage).
   static bool ValidateMessageIntegrity(const char* data, size_t size,
                                        const std::string& password);
@@ skipping 463 matching lines @@
       case STUN_ATTR_ICE_CONTROLLING: return STUN_VALUE_UINT64;
       default: return StunMessage::GetAttributeValueType(type);
     }
   }
   virtual StunMessage* CreateNew() const { return new IceMessage(); }
 };
 
 }  // namespace cricket
 
 #endif  // WEBRTC_P2P_BASE_STUN_H_