int MQTT::Client::cycle()

in AZ3166/src/libraries/MQTT/src/MQTTClient.h [481:557]
72 lines of code
23 McCabe index (conditional complexity)

int MQTT::Client<Network, Timer, MAX_MQTT_PACKET_SIZE, b>::cycle(Timer& timer)
{
    /* get one piece of work off the wire and one pass through */

    // read the socket, see what work is due
    unsigned short packet_type = readPacket(timer);

    int len = 0,
        rc = SUCCESS;

    switch (packet_type)
    {
        case CONNACK:
        case PUBACK:
        case SUBACK:
            break;
        case PUBLISH:
            MQTTString topicName;
            Message msg;
            if (MQTTDeserialize_publish((unsigned char*)&msg.dup, (int*)&msg.qos, (unsigned char*)&msg.retained, (unsigned short*)&msg.id, &topicName,
                                 (unsigned char**)&msg.payload, (int*)&msg.payloadlen, readbuf, MAX_MQTT_PACKET_SIZE) != 1)
                goto exit;
#if MQTTCLIENT_QOS2
            if (msg.qos != QOS2)
#endif
                deliverMessage(topicName, msg);
#if MQTTCLIENT_QOS2
            else if (isQoS2msgidFree(msg.id))
            {
                if (useQoS2msgid(msg.id))
                    deliverMessage(topicName, msg);
                else
                    WARN("Maximum number of incoming QoS2 messages exceeded");
            }   
#endif
#if MQTTCLIENT_QOS1 || MQTTCLIENT_QOS2
            if (msg.qos != QOS0)
            {
                if (msg.qos == QOS1)
                    len = MQTTSerialize_ack(sendbuf, MAX_MQTT_PACKET_SIZE, PUBACK, 0, msg.id);
                else if (msg.qos == QOS2)
                    len = MQTTSerialize_ack(sendbuf, MAX_MQTT_PACKET_SIZE, PUBREC, 0, msg.id);
                if (len <= 0)
                    rc = FAILURE;
                else
                    rc = sendPacket(len, timer);
                if (rc == FAILURE)
                    goto exit; // there was a problem
            }
            break;
#endif
#if MQTTCLIENT_QOS2
        case PUBREC:
            unsigned short mypacketid;
            unsigned char dup, type;
            if (MQTTDeserialize_ack(&type, &dup, &mypacketid, readbuf, MAX_MQTT_PACKET_SIZE) != 1)
                rc = FAILURE;
            else if ((len = MQTTSerialize_ack(sendbuf, MAX_MQTT_PACKET_SIZE, PUBREL, 0, mypacketid)) <= 0)
                rc = FAILURE;
            else if ((rc = sendPacket(len, timer)) != SUCCESS) // send the PUBREL packet
                rc = FAILURE; // there was a problem
            if (rc == FAILURE)
                goto exit; // there was a problem
            break;
        case PUBCOMP:
            break;
#endif
        case PINGRESP:
            ping_outstanding = false;
            break;
    }
    keepalive();
exit:
    if (rc == SUCCESS)
        rc = packet_type;
    return rc;
}