发送端

#include<sys/socket.h>
#include<stdio.h>
#include<arpa/inet.h>
#include<unistd.h>
#include<string.h>
int main()
{
    int ret;
    int sfd=socket(AF_INET,SOCK_DGRAM,0);
    if(sfd==-1)perror("socket error");
    struct in_addr address;
    inet_pton(AF_INET,"239.0.0.10",&address.s_addr);
    setsockopt(sfd,IPPROTO_IP,IP_MULTICAST_IF,&address,sizeof(address));
    struct sockaddr_in caddr;
    caddr.sin_family=AF_INET;
    caddr.sin_port=htons(8888);
    inet_pton(AF_INET,"192.168.101.231",&caddr.sin_addr.s_addr);
    int caddrlen=sizeof(caddr);
    while(true)
    {
        ret=sendto(sfd,"this is send host",strlen("this is send host"),0,(struct sockaddr*)&caddr,caddrlen);
        if(ret==-1)
        {
            perror("sendto error");
            break;
        }
        sleep(1);
    }
    close(sfd);
    return 0;
}

接收端

#include<sys/socket.h>
#include<stdio.h>
#include<arpa/inet.h>
#include<unistd.h>
#include<string.h>
#include<net/if.h>
int main()
{
    int ret;
    int rfd=socket(AF_INET,SOCK_DGRAM,0);
    if(rfd==-1)perror("socket error");
    struct ip_mreqn mreqn;
    inet_pton(AF_INET,"192.168.101.231",&mreqn.imr_address);//本地地址
    inet_pton(AF_INET,"239.0.0.10",&mreqn.imr_address);//多播地址
    mreqn.imr_ifindex=if_nametoindex("ens33");//获取网卡编号
    setsockopt(rfd,IPPROTO_IP,IP_ADD_MEMBERSHIP,&mreqn,sizeof(mreqn));
    struct sockaddr_in raddr;
    raddr.sin_family=AF_INET;
    raddr.sin_port=htons(8888);
    inet_pton(AF_INET,"192.168.101.231",&raddr.sin_addr.s_addr);
    int raddrlen=sizeof(raddr);
    ret=bind(rfd,(struct sockaddr*)&raddr,raddrlen);
    if(ret==-1)perror("bind error");
    char buffer[1024]={'\0'};
    while(true)
    {
        ret=recvfrom(rfd,buffer,1024,0,(struct sockaddr*)&raddr,(socklen_t*)&raddrlen);
        if(ret==-1)
        {
            perror("recv error");
            break;
        }
        else if(ret==0)
        {
            printf("连接断开\n");
            break;
        }
        else
        {
            printf("收到了数据:%s\n",buffer);
        }
    }
    close(rfd);
    return 0;
}