mqtt_receive

void mqtt_receive(void *pvParameters)
{
    int32_t buffer_len = sizeof(buffer);
    int32_t type;
    fd_set readfd;
    fd_set errofds;
    struct timeval tv; // 等待时间
    tv.tv_sec = 4;
    tv.tv_usec = 0;
    int ret = 0;
    int recv_ret = 0;

MQTT_RECEIVE_START:
    // 开始连接
    Client_Connect();

    Para_Packet_New = 0;

    // 获取当前滴答，作为心跳包起始时间
    curtick = xTaskGetTickCount();

    while (1)
    {
        if (Para_Packet_New == 1)
        {
            goto MQTT_RECEIVE_CLOSE;
        }

        mqtt_connected = 1;

        // 推送消息
        FD_ZERO(&readfd);
        FD_SET(MQTT_Socket, &readfd);
        FD_ZERO(&errofds);
        FD_SET(MQTT_Socket, &errofds);

        // 等待可读事件
        int ret = select(MQTT_Socket + 1, &readfd, NULL, &errofds, &tv);

        // if (ret > 0 )
        if (FD_ISSET(MQTT_Socket, &readfd) != 0)
        {
            memset(buffer, '\0', sizeof(buffer));

            recv_ret = recv(MQTT_Socket, &buffer[0], buffer_len, 0);

            if (recv_ret <= 0)
            {
                goto MQTT_RECEIVE_CLOSE;
            }

            if (recv_ret > 0)
            {
                curtick = xTaskGetTickCount();

                int index = 0;
                int k = 0;

                char *ret = NULL;

                for (k = 0; k < 20; k++)
                {
                    ret = strstr(buffer + k, Topic);

                    if (ret != NULL)
                    {
                        break;
                    }
                }

                if (ret != NULL)
                {
                  index = strlen(Topic) + 1 + k;

                  decode_action((char*)&buffer[index], SN);
                }
            }
        }
        else
        {
            // 这里主要目的是定时向服务器发送PING保活命令
            uint32_t elapse_tick = xTaskGetTickCount() - curtick;

            if (elapse_tick > (MQTT_PING_INTERVAL_TIME * 1000))
            {
                curtick = xTaskGetTickCount();

                int z = MQTT_PingReq(MQTT_Socket);

                char log_str[50];
                memset(log_str, '\0', sizeof(log_str));

                if (z < 0)
                {
                    sprintf(log_str, "MQTT_PingReq return %d\n", z);
                    uart_printf(log_str, strlen(log_str));
                    // 重连服务器
                    uart_printf("Failed to send a keep-alive ping...\n", strlen("Failed to send a keep-alive ping...\n"));

                    if (++mqtt_pingreq_fail_cnt >= 3)
                    {
                        mqtt_pingreq_fail_cnt = 0;
                        goto MQTT_RECEIVE_CLOSE;
                    }
                }
                else
                {
                    mqtt_pingreq_fail_cnt = 0;
                    // 心跳成功
                    uart_printf("Succeeded to send a keep-alive ping...\n", strlen("Succeeded to send a keep-alive ping...\n"));
                }
            }
        }
    }

MQTT_RECEIVE_CLOSE:
    // 关闭链接
    mqtt_connected = 0;
    transport_close();
    // 重新链接服务器
    goto MQTT_RECEIVE_START;
}