5 kawaii-mqtt sim7600 mqtt服务器切换

发布于 2022-09-28 17:44:05 浏览：570 订阅该版

应用层：kawaii-maqtt
运输层：RT-Thread SAL
底层：  sim7600

为了防止产品使用过程中，mqtt服务器失效，另行准备2个备用mqtt服务器，共计3个mqtt服务器。
计划当mqtt broker1失效时，mqtt客户端切换连接mqtt broker2,依次类推。
```c
// 与服务器建立连接
    if (mqtt_connect(MQTTClintTemp) != KAWAII_MQTT_SUCCESS_ERROR)
    {
        KAWAII_MQTT_LOG_E("MQTT Client Failed to connect with MQTT Server!\n");
        // mqtt_set_client_state(MQTTClintTemp, CLIENT_STATE_DISCONNECTED);
        // DisconnectMQTTServer(MQTTClient);
        // mqtt_sleep_ms(1000);

mqtt_set_port(MQTTClintTemp, MQTT_PORT_1);
        mqtt_set_host(gpClient, MQTT_HOST_1);
        mqtt_set_user_name(gpClient, MQTT_USER_NAME_1);
        mqtt_set_password(gpClient, MQTT_PASSWORD_1);
        mqtt_set_client_id(gpClient, "gsClientIDnext");

if (mqtt_connect(MQTTClintTemp) != KAWAII_MQTT_SUCCESS_ERROR)
        {
            KAWAII_MQTT_LOG_E("MQTT Client Failed to connect with MQTT Server!\n");
            return 1;
        }
    }
```
但是在实际尝试时，一旦mqtt broker1失效，mqtt broker2也连接不成功。
报如下错误：
```
[E/at.clnt] execute command (AT+CIPCLOSE=0) failed!
[E/at.clnt] execute command (AT+CIPOPEN=0,"TCP","xxx.xxx.xxx.xxx",xxx) failed!
[E/at.clnt] execute command (AT+CIPCLOSE=0) failed!
[E/at.clnt] execute command (AT+CIPCLOSE=0) failed!
```
求解。。。。

1 个回答

小权一句两句 2022-09-28

似此星辰非昨夜，为谁风露立中宵

我之前也在这个软件包遇到了几个问题在这里分享一下我是怎么找到问题的吧

1. 是没对齐的问题，这里我打了一个补丁[https://github.com/jiejieTop/mqttclient/pull/63](https://github.com/jiejieTop/mqttclient/pull/63)，但是作者没合，你可以参考一下

2. 如果订阅的信息不是直接写死的，比如name是malloc出来零时赋值的，传给mqtt后又被free了，这时也会出现一些问题，因为这个软件包只保存了那个临时指针，并没有保存真实的数据，修复方式类似于这样，以topic为例，其他的像name一样的类推:

```c
static message_handlers_t *mqtt_msg_handler_create(const char *topic_filter, mqtt_qos_t qos, message_handler_t handler)
{
    message_handlers_t *msg_handler = NULL;

msg_handler = (message_handlers_t *)platform_memory_alloc(sizeof(message_handlers_t));
    if (NULL == msg_handler)
        return NULL;

mqtt_list_init(&msg_handler->list);

msg_handler->qos          = qos;
    msg_handler->handler      = handler; /* register  callback handler */
    msg_handler->topic_filter = rt_malloc(rt_strlen(topic_filter) + 1);
    rt_strncpy(msg_handler->topic_filter, topic_filter, rt_strlen(topic_filter) + 1);

return msg_handler;
}
```

记得在释放的时候也销毁掉

```c
static void mqtt_msg_handler_destory(message_handlers_t *msg_handler)
{
    if (NULL != &msg_handler->list) {
        mqtt_list_del(&msg_handler->list);
        platform_memory_free(msg_handler->topic_filter);
        platform_memory_free(msg_handler);
    }
}
```