check retained flag on received message

[lucabuka]

Hi, first of all thanks for the great lib. I'm trying to find a way to check if the received message have the Retained Flag set. In other words i need to recognize if the received message is a retained message or a standard (not retained) one. I've check onMessageAdvanced() but i don't see a way to get the information i need.

Am i missing something or actually this information is not available via the callback method ? TIA

[lucabuka]

After checking the src files i can confirm the 'retained' flag of the incoming message is not returned by onMessage() or onMessageAdvanced. In source file MQTTClient.cpp the function MQTTClientHandler() receives a lwmqtt_message_t parameter. This struct, defined in lwmqtt/lwmqtt.h contains the retained message flag:

typedef struct {
  lwmqtt_qos_t qos;
  bool retained;
  uint8_t *payload;
  size_t payload_len;
} lwmqtt_message_t;

but this bool value is not managed in the AdvancedCallback:

typedef void (*MQTTClientCallbackAdvanced)(MQTTClient *client, char topic[], char bytes[], int length);

--

So i modified the library adding new callback function (MQTTClient.cpp, MQTTClient.h) :**

void onMessageDetailed(MQTTClientCallbackDetailedFunction cb);
// Callback signature: std::function<void(MQTTClient *client, char topic[], char bytes[], int length, bool retained, lwmqtt_qos_t qos )>

This way i now have available the message "retained" flag and there are no compatibility issues with my other sources using the Advanced Callback.