5 mqtt软件包通讯使用问题

typedef struct MQTTMessage
{
    enum QoS qos;
    unsigned char retained;
    unsigned char dup;
    unsigned short id;
    void *payload;
    size_t payloadlen;
} MQTTMessage;

int paho_mqtt_publish(MQTTClient *client, enum QoS qos, const char *topic, const char *msg_str)
{
    static unsigned short id = 0;
    MQTTMessage message = {0};
    if (qos != QOS1)
    {
        LOG_E("Not support Qos(%d) config, only support Qos(d).", qos, QOS1);
        return PAHO_FAILURE;
    }
    if (++id == 0)
    {
        ++id;
    }
    message.qos = qos;
    message.retained = 0;
    message.id = id;
    message.payload = (void *)msg_str;
    message.payloadlen = rt_strlen(message.payload);
    if (client->isblocking && client->pub_sem)
    {
        if(rt_sem_take(client->pub_sem, 5 * RT_TICK_PER_SECOND) < 0)
        {
            return PAHO_FAILURE;
        }
    }
    return MQTTPublish(client, topic, &message);
}