mosquitto c example 发布示例

此处使用同步连接模式来发布消息，mosquitto有同步和异步两种通讯方式。同步的方式是通信+等待的阻塞模式。
官方手册api地址：https://mosquitto.org/api/files/mosquitto-h.html#mosquitto_connect
有疑问的地方，可以直接看官方手册，比较好懂。

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "mosquitto.h"

#define HOST "localhost"
#define PORT  1883
#define KEEP_ALIVE 60
#define MSG_MAX_SIZE  512

static int running = 1;

void my_connect_callback(struct mosquitto *mosq, void *obj, int rc)
{
        printf("Call the function: my_connect_callback\n");

}

void my_disconnect_callback(struct mosquitto *mosq, void *obj, int rc)
{
        printf("Call the function: my_disconnect_callback\n");
        running = 0;
}

void my_publish_callback(struct mosquitto *mosq, void *obj, int mid)
{
        printf("Call the function: my_publish_callback\n");

}


int main()
{
        int ret;
        struct mosquitto *mosq;
        char buff[MSG_MAX_SIZE];
        
        //初始化libmosquitto库
        ret = mosquitto_lib_init();
        if(ret){
                printf("Init lib error!\n");
                return -1;
        }
        //创建一个发布端实例
        mosq =  mosquitto_new("pub_test", true, NULL);
        if(mosq == NULL){
                printf("New pub_test error!\n");
                mosquitto_lib_cleanup();
                return -1;
        }

        //设置回调函数
        mosquitto_connect_callback_set(mosq, my_connect_callback);
        mosquitto_disconnect_callback_set(mosq, my_disconnect_callback);
        mosquitto_publish_callback_set(mosq, my_publish_callback);

        // 连接至服务器
        // 参数：句柄、ip（host）、端口、心跳
        ret = mosquitto_connect(mosq, HOST, PORT, KEEP_ALIVE);
        if(ret){
                printf("Connect server error!\n");
                mosquitto_destroy(mosq);
                mosquitto_lib_cleanup();
                return -1;
        }

        printf("Start!\n");
        
        //mosquitto_loop_start作用是开启一个线程，在线程里不停的调用 mosquitto_loop() 来处理网络信息
        
        int loop = mosquitto_loop_start(mosq); 
        if(loop != MOSQ_ERR_SUCCESS)
        {
            printf("mosquitto loop error\n");
            return 1;
        }


        while(fgets(buff, MSG_MAX_SIZE, stdin) != NULL)
        {
            /*发布消息*/
            mosquitto_publish(mosq,NULL,"topic1",strlen(buff)+1,buff,0,0);
            memset(buff,0,sizeof(buff));
        }

        mosquitto_destroy(mosq);
        mosquitto_lib_cleanup();
        printf("End!\n");

        return 0;
}

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