IotMqtt_DeserializePublish

Deserialize incoming publish packet.

IotMqttError_t IotMqtt_DeserializePublish( IotMqttPacketInfo_t * pMqttPacket );

Parameters

[in,out]

pMqttPacket

The caller of this API sets type, remainingLength and pRemainingData. On success, packetIdentifier and pubInfo will be set by the function.

Returns

One of the following:

• IOT_MQTT_SUCCESS
• IOT_MQTT_BAD_RESPONSE
• IOT_MQTT_SERVER_REFUSED

Note

This call is part of serializer API used for implementing light-weight MQTT client.

Example

// Example below shows how IotMqtt_DeserializePublish() used to extract contents of incoming
// Publish.  xMQTTSocket here is posix socket created and connected to MQTT broker outside of this function.
void processIncomingPublish( int xMQTTSocket )
{
   IotMqttError_t xResult;
   IotMqttPacketInfo_t xIncomingPacket;

   xResult = IotMqtt_GetIncomingMQTTPacketTypeAndLength( &xIncomingPacket, getNextByte, ( void * ) xMQTTSocket );
   IotMqtt_Assert( xResult == IOT_MQTT_SUCCESS );
   IotMqtt_Assert( ( xIncomingPacket.type & 0xf0 ) == MQTT_PACKET_TYPE_PUBLISH );
   IotMqtt_Assert( xIncomingPacket.remainingLength <= mqttexampleSHARED_BUFFER_SIZE );

   // Receive the remaining bytes.
   if( recv( xMQTTSocket, ( void * ) ucSharedBuffer, xIncomingPacket.remainingLength, 0 ) ==  xIncomingPacket.remainingLength )
   {
    xIncomingPacket.pRemainingData = ucSharedBuffer;

    if( IotMqtt_DeserializePublish( &xIncomingPacket ) != IOT_MQTT_SUCCESS )
    {
        xResult = IOT_MQTT_BAD_RESPONSE;
    }
    else
    {
        // Process incoming Publish.
        IotLogInfo( "Incoming QOS : %d\n", xIncomingPacket.pubInfo.qos );
        IotLogInfo( "Incoming Publish Topic Name: %.*s\n", xIncomingPacket.pubInfo.topicNameLength, xIncomingPacket.pubInfo.pTopicName );
        IotLogInfo( "Incoming Publish Message : %.*s\n", xIncomingPacket.pubInfo.payloadLength, xIncomingPacket.pubInfo.pPayload  );
    }
   }
   else
   {
    xResult = IOT_MQTT_NETWORK_ERROR;
   }

 IotMqtt_Assert( xResult == IOT_MQTT_SUCCESS );
}