static MQTTStatus_t deserializeConnack()

in source/core_mqtt_serializer.c [923:1002]
58 lines of code
8 McCabe index (conditional complexity)

static MQTTStatus_t deserializeConnack( const MQTTPacketInfo_t * pConnack,
                                        bool * pSessionPresent )
{
    MQTTStatus_t status = MQTTSuccess;
    const uint8_t * pRemainingData = NULL;

    assert( pConnack != NULL );
    assert( pSessionPresent != NULL );
    pRemainingData = pConnack->pRemainingData;

    /* According to MQTT 3.1.1, the second byte of CONNACK must specify a
     * "Remaining length" of 2. */
    if( pConnack->remainingLength != MQTT_PACKET_CONNACK_REMAINING_LENGTH )
    {
        LogError( ( "CONNACK does not have remaining length of %u.",
                    ( unsigned int ) MQTT_PACKET_CONNACK_REMAINING_LENGTH ) );

        status = MQTTBadResponse;
    }

    /* Check the reserved bits in CONNACK. The high 7 bits of the third byte
     * in CONNACK must be 0. */
    else if( ( pRemainingData[ 0 ] | 0x01U ) != 0x01U )
    {
        LogError( ( "Reserved bits in CONNACK incorrect." ) );

        status = MQTTBadResponse;
    }
    else
    {
        /* Determine if the "Session Present" bit is set. This is the lowest bit of
         * the third byte in CONNACK. */
        if( ( pRemainingData[ 0 ] & MQTT_PACKET_CONNACK_SESSION_PRESENT_MASK )
            == MQTT_PACKET_CONNACK_SESSION_PRESENT_MASK )
        {
            LogDebug( ( "CONNACK session present bit set." ) );
            *pSessionPresent = true;

            /* MQTT 3.1.1 specifies that the fourth byte in CONNACK must be 0 if the
             * "Session Present" bit is set. */
            if( pRemainingData[ 1 ] != 0U )
            {
                LogError( ( "Session Present bit is set, but connect return code in CONNACK is %u (nonzero).",
                            ( unsigned int ) pRemainingData[ 1 ] ) );
                status = MQTTBadResponse;
            }
        }
        else
        {
            LogDebug( ( "CONNACK session present bit not set." ) );
            *pSessionPresent = false;
        }
    }

    if( status == MQTTSuccess )
    {
        /* In MQTT 3.1.1, only values 0 through 5 are valid CONNACK response codes. */
        if( pRemainingData[ 1 ] > 5U )
        {
            LogError( ( "CONNACK response %u is invalid.",
                        ( unsigned int ) pRemainingData[ 1 ] ) );

            status = MQTTBadResponse;
        }
        else
        {
            /* Print the appropriate message for the CONNACK response code if logs are
             * enabled. */
            logConnackResponse( pRemainingData[ 1 ] );

            /* A nonzero CONNACK response code means the connection was refused. */
            if( pRemainingData[ 1 ] > 0U )
            {
                status = MQTTServerRefused;
            }
        }
    }

    return status;
}