Application crashing after DUPLICATE_CLIENT_ID error

[Aseem90]

Hi There,

I am using AWS Device SDK (CPP V2) to build my AWS Agent for my Network Communication Module. I am using MQTT5 for connection to AWS. I can see my application getting crashed when 2 different devices are using same Thing Id and device certificates which I know that AWS will disconnect the first client with reason, "Duplicate Client ID" and connect to another device which has same client Id (Thing Id) and certificates.

My question is, I have setup a Disconnect Callback as below :

      // Callback for Disconnection
      mqtt5Builder->WithClientDisconnectionCallback([this]
      (const Aws::Crt::Mqtt5::OnDisconnectionEventData& eventData) 
      {
          LOG_I("MQTT5 Client has been disconnected with AWS [%s].",
          aws_error_debug_str(eventData.errorCode));
  
          // Internal variables
          m_Connected = false;
  
          // Crashed here =======================================
          if (!eventData.disconnectPacket)
          {
              return ;
          }
  
          LOG_I("The reason code: %d and reason string: %s",
          eventData.disconnectPacket->getReasonCode(),
          eventData.disconnectPacket->getReasonString()->c_str());
      });

Any particular reason or anything I am missing in my implementation?

[bretambrose]

Hard to say without understanding the lifetimes of the various objects in your application. What does the debugger tell you? Lambda capture doesn't keep anything alive, so if your this is destroyed before the client is stopped, the captured this pointer might be garbage, for example, and then this->m_Connected is going to crash.