OtaErr_t requestJob_Mqtt()

in source/ota_mqtt.c [840:934]

• 66 lines of code
• 5 McCabe index (conditional complexity)

OtaErr_t requestJob_Mqtt( OtaAgentContext_t * pAgentCtx )
{
    /* This buffer is used to store the generated MQTT topic. The static size
     * is calculated from the template and the corresponding parameters. */
    char pJobTopic[ TOPIC_GET_NEXT_BUFFER_SIZE ];

    /* The following buffer is big enough to hold a dynamically constructed
     * $next/get job message. It contains a client token that is used to track
     * how many requests have been made. */
    char pMsg[ MSG_GET_NEXT_BUFFER_SIZE ];

    static uint32_t reqCounter = 0;
    OtaErr_t otaError = OtaErrRequestJobFailed;
    OtaMqttStatus_t mqttStatus = OtaMqttSuccess;
    uint32_t msgSize = 0;
    uint16_t topicLen = 0;

    /* NULL-terminated list of topic string parts. */
    const char * pTopicParts[] =
    {
        MQTT_API_THINGS,
        NULL, /* Thing Name not available at compile time, initialized below. */
        MQTT_API_JOBS_NEXT_GET,
        NULL
    };
    char reqCounterString[ U32_MAX_LEN + 1 ];
    /* NULL-terminated list of payload parts */
    /* NOTE: this must agree with pOtaGetNextJobMsgTemplate, do not add spaces, etc. */
    const char * pPayloadParts[] =
    {
        "{\"clientToken\":\"",
        NULL, /* Request counter string not available at compile time, initialized below. */
        ":",
        NULL, /* Thing Name not available at compile time, initialized below. */
        "\"}",
        NULL
    };

    assert( pAgentCtx != NULL );

    /* Suppress warnings about unused variables. */
    ( void ) pOtaJobsGetNextTopicTemplate;
    ( void ) pOtaGetNextJobMsgTemplate;

    pTopicParts[ 1 ] = ( const char * ) pAgentCtx->pThingName;
    pPayloadParts[ 1 ] = reqCounterString;
    pPayloadParts[ 3 ] = ( const char * ) pAgentCtx->pThingName;

    ( void ) stringBuilderUInt32Decimal( reqCounterString, sizeof( reqCounterString ), reqCounter );

    /* Subscribe to the OTA job notification topic. */
    mqttStatus = subscribeToJobNotificationTopics( pAgentCtx );

    if( mqttStatus == OtaMqttSuccess )
    {
        LogDebug( ( "MQTT job request number: counter=%u", reqCounter ) );

        msgSize = ( uint32_t ) stringBuilder(
            pMsg,
            sizeof( pMsg ),
            pPayloadParts );

        /* The buffer is static and the size is calculated to fit. */
        assert( ( msgSize > 0U ) && ( msgSize < sizeof( pMsg ) ) );

        reqCounter++;

        topicLen = ( uint16_t ) stringBuilder(
            pJobTopic,
            sizeof( pJobTopic ),
            pTopicParts );

        /* The buffer is static and the size is calculated to fit. */
        assert( ( topicLen > 0U ) && ( topicLen < sizeof( pJobTopic ) ) );

        mqttStatus = pAgentCtx->pOtaInterface->mqtt.publish( pJobTopic, topicLen, pMsg, msgSize, 1 );

        if( mqttStatus == OtaMqttSuccess )
        {
            LogDebug( ( "Published MQTT request to get the next job: "
                        "topic=%s",
                        pJobTopic ) );
            otaError = OtaErrNone;
        }
        else
        {
            LogError( ( "Failed to publish MQTT message:"
                        "publish returned error: "
                        "OtaMqttStatus_t=%s",
                        OTA_MQTT_strerror( mqttStatus ) ) );
        }
    }

    return otaError;
}