Linux C/C++组播

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一、流程实现

二、代码实现

1.服务器

代码如下（示例）：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <arpa/inet.h>

int main()
{
    // 1.创建一个通信的socket
    int fd = socket(PF_INET, SOCK_DGRAM, 0);

    if (fd == -1)
    {
        perror("socket");
        exit(-1);
    }

    // 2.设置多播属性，设置外出接口
    struct in_addr imr_multiaddr;
    //初始化多播地址
    inet_pton(AF_INET, "239.0.0.10", &imr_multiaddr.s_addr);
    setsockopt(fd, IPPROTO_IP, IP_MULTICAST_IF, &imr_multiaddr, sizeof(imr_multiaddr));

    //3.初始化客户端的地址信息
    struct sockaddr_in caddr;
    caddr.sin_family = AF_INET;
    caddr.sin_port = htons(9999);
    inet_pton(AF_INET,"239.0.0.10",&caddr.sin_addr.s_addr);

    // 4.通信
    int num = 0;
    while (1)
    {
        char sendbuf[128];
        sprintf(sendbuf, "hello,client.....%d\n", num++);
        //发送数据
        sendto(fd, sendbuf, strlen(sendbuf) + 1,0,(struct sockaddr*)&caddr,sizeof(caddr));
        printf("组播的数据：%s\n", sendbuf);
        sleep(1);
    }

    close(fd);

    return 0;
}

2.客户端

代码如下（示例）：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <arpa/inet.h>

int main()
{
    // 1.创建一个通信的socket
    int fd = socket(PF_INET, SOCK_DGRAM, 0);

    if (fd == -1)
    {
        perror("socket");
        exit(-1);
    }

    //2.客户端绑定本地的IP和端口号
    struct sockaddr_in addr;
    addr.sin_family = AF_INET;
    addr.sin_port = htons(9999);
    addr.sin_addr.s_addr = INADDR_ANY;

    int ret = bind(fd, (struct sockaddr *)&addr, sizeof(addr));
    if(ret ==-1 )
    {
        perror("bind");
        exit(-1);
    }

    struct ip_mreq op;
    inet_pton(AF_INET, "239.0.0.10", &op.imr_multiaddr.s_addr);
    op.imr_interface.s_addr = INADDR_ANY;
    //加入到多播组
    setsockopt(fd, IPPROTO_IP, IP_ADD_MEMBERSHIP, &op, sizeof(op));

    // 3.通信
    while (1)
    {
        char buf[128];
        //接受数据
        int num = recvfrom(fd, buf, sizeof(buf), 0, NULL, NULL);
        printf("server say:%s\n", buf);

    }

    close(fd);

    return 0;
}

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