使用UDP套接字实现多播消息

发送方代码如下：

#include
#include
#include
#include
#include
#include
#include
#include

#define N 64

typedef struct sockaddr SA;

int main(int argc, char *argv[])
{
 int sockfd;
 socklen_t addr_len;
 char buf[N];
 struct sockaddr_in multiaddr;

 if (argc < 3)
 {
  printf("input format is : %s    \n", argv[0]);
  return -1;
 }

 if ((sockfd = socket(PF_INET, SOCK_DGRAM, 0)) == -1)
 {
  perror("sock fail");
  return -1;
 }

 multiaddr.sin_family = PF_INET;
 multiaddr.sin_port = htons(atoi(argv[2]));
 multiaddr.sin_addr.s_addr = inet_addr(argv[1]);

 strcpy(buf, "nobody nobody but you\n");
 while (1)
 {
  addr_len = sizeof(multiaddr);
  sendto(sockfd, buf, N, 0, (SA *)&multiaddr, addr_len);
  sleep(1);
 }

 return 0;
}

 

接收方代码如下：

#include
#include
#include
#include
#include
#include
#include

#define N 64

typedef struct sockaddr SA;

int main(int argc, char *argv[])
{
 int sockfd;
 socklen_t addr_len;
 char buf[N];
 struct sockaddr_in recvaddr, sendaddr;
 struct ip_mreq mreq;

 if (argc < 2)
 {
  printf("input format is : %s \n", argv[0]);
  return -1;
 }

 if ((sockfd = socket(PF_INET, SOCK_DGRAM, 0)) == -1)
 {
  perror("sock fail");
  return -1;
 }

 bzero(&mreq, sizeof(mreq));
 mreq.imr_multiaddr.s_addr = inet_addr("224.10.10.1");
 mreq.imr_interface.s_addr = htonl(INADDR_ANY);
 if (setsockopt(sockfd, IPPROTO_IP, IP_ADD_MEMBERSHIP, &mreq, sizeof(mreq)) == -1)
 {
  perror("setsockopt fail\n");
  exit(1);
 }

 recvaddr.sin_family = PF_INET;
 recvaddr.sin_port = htons(atoi(argv[2]));
 recvaddr.sin_addr.s_addr = htonl(INADDR_ANY);

 if (bind(sockfd, (SA *)&recvaddr, sizeof(recvaddr)) == -1)
 {
  perror("bind fail");
  return -1;
 }

 while (1)
 {
  addr_len = sizeof(sendaddr);
  recvfrom(sockfd, buf, N, 0, (SA *)&sendaddr, &addr_len);
  printf("recv from %s[%d]:%s\n", inet_ntoa(sendaddr.sin_addr),
          ntohs(sendaddr.sin_port), buf);
 }

 return 0;
}