#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <netdb.h>
#include <errno.h>
#define BUFLEN 1000
int
main (int argc, char **argv)
{
struct sockaddr_in peeraddr,ia;
int sockfd;
char recmsg[BUFLEN + 1];
unsigned int socklen, n;
struct ip_mreq mreq;
/* 創建 socket 用於UDP通訊 */
sockfd = socket (AF_INET, SOCK_DGRAM, 0);
if (sockfd < 0)
{ printf ("socket creating err in udptalk\n");
exit (1);
}
/* 設置要加入組播的地址 */
bzero(&mreq, sizeof (struct ip_mreq));
inet_pton(AF_INET,"226.1.1.1",&ia.sin_addr);//組播地址
/* 設置組地址 */
bcopy (&ia.sin_addr.s_addr, &mreq.imr_multiaddr.s_addr, sizeof (struct in_addr));
/* 設置發送和接收源主機的地址信息 */
// mreq.imr_interface.s_addr = htonl (INADDR_ANY);
//這樣寫是否能綁定到對應的網卡上
mreq.imr_interface.s_addr = inet_addr("192.168.2.110");
/* 把本機加入組播地址，即本機網卡作爲組播成員，只有加入組才能收到組播消息 */
if (setsockopt(sockfd, IPPROTO_IP, IP_ADD_MEMBERSHIP, &mreq,sizeof (struct ip_mreq)) == -1)
{ perror ("setsockopt");
exit (-1);
}
socklen = sizeof (struct sockaddr_in);
memset (&peeraddr, 0, socklen);
peeraddr.sin_family = AF_INET;
peeraddr.sin_port = htons (9999);//組播端口
inet_pton(AF_INET, "226.1.1.1", &peeraddr.sin_addr); //組播地址
int opt = 1;
// sockfd爲需要端口複用的套接字
setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, (const void *)&opt, sizeof(opt));
/* 綁定自己的端口和IP信息到socket上 */
if (bind(sockfd, (struct sockaddr *) &peeraddr,sizeof (struct sockaddr_in)) == -1)
{ printf ("Bind error\n");
exit (0);
}
/* 循環接收網絡上來的組播消息 */
for (;;)
{ bzero (recmsg, BUFLEN + 1);
n = recvfrom (sockfd, recmsg, BUFLEN, 0, (struct sockaddr *) &peeraddr, &socklen);
if (n < 0)
{
printf ("recvfrom err in udptalk!\n");
exit (4);
}
else
{ /* 成功接收到數據報 */
recmsg[n] = 0;
fflush(stdout);
printf ("peer:");
}
}
}