Random error in MQTTClient::loop() function

[martinch14]

  // get available bytes on the network
  auto available = (size_t)this->netClient->available();

  // yield if data is available
  if (available > 0) {
    this->_lastError = lwmqtt_yield(&this->client, available, this->timeout);
    if (this->_lastError != LWMQTT_SUCCESS) {
      // close connection
      this->close();

      return false;
    }
  }

I am testing an mqtt broker, and I have random disconnection problems, I am sending one message per second, sometimes the disconnection happens quickly, sometimes I send up to 1000 messages without problems.

The disconnection event occurs when the call to the function (size_t)this->netClient->available(); results in the value available:4294967220 In all other cases the result is zero.

when the result is 4294967220 causes it to enter to the if() loop and then close the connection,

If I comment this line of code, I can send without problems and without losing messages,

Do you have any idea what could be happening?

I can detect the disconnection and reconnect, but I would like to avoid it, since it is the device that is disconnecting, it is not a question of internet access either, because I try it with different devices and the disconnections occur at different times, It is the device that disconnects from the broker

[256dpi]

Thanks for the report, the included snippet made me think and I found an integer casting issue:

auto available = (size_t)this->netClient->available();

The available method actually returns an int, so my feeling is that your network layer may return a negative number to indicate an error code. When casting it to size_t the number becomes very large due to "Two's Complement".

I fixed the issue and released a new version. Let me know if it helps.

[martinch14]

Hi @256dpi Apply the mentioned changes and uncomment that part of the code in my firmware. I've been testing this for a few days and for now I don't have any disconnection events, I think the problem is solved.

Thank you so much