多组播

头文件：sock.h
封装函数wrap.c

服务器：

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <fcntl.h>
#include <time.h>
#include <errno.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sock.h>

#define MAXSIZE 64

void usage(const char *info)
{
 printf("Usage : %s <multi_ip> <port>\n", info);
 exit(0);
}

int main(int argc, char *argv[])
{
 if (argc != 3)
  usage(argv[0]);

 int sockfd;
 char buf[MAXSIZE];

 struct sockaddr_in myaddr, peeraddr;

 sockfd = Socket(PF_INET, SOCK_DGRAM, 0);

 /* ======= add in multicast group ========= */
 struct ip_mreq mreq;
 bzero(&mreq, sizeof(mreq));
 // mutiladdr: 224.0.0.1 ~ 239.255.255.255
 mreq.imr_multiaddr.s_addr = inet_addr(argv[1]);
 // local interface
 mreq.imr_interface.s_addr = htonl(INADDR_ANY);

 Setsockopt(sockfd, IPPROTO_IP, IP_ADD_MEMBERSHIP,
   &mreq, sizeof(mreq));
 /* ======================================== */

 bzero(&myaddr, sizeof(myaddr));
 myaddr.sin_family = PF_INET;
 myaddr.sin_port = htons(atoi(argv[2]));
 myaddr.sin_addr.s_addr = htonl(INADDR_ANY);

 Bind(sockfd, (struct sockaddr *)&myaddr, sizeof(myaddr));

 socklen_t len = sizeof(peeraddr);

 while(1){

  recvfrom(sockfd, buf, MAXSIZE, 0,
    (struct sockaddr *)&peeraddr, &len);

  printf("recv from [%s:%d] : %s\n",
    inet_ntoa(peeraddr.sin_addr),
    ntohs(peeraddr.sin_port), buf);
 }

 return 0;
}

客服端：

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <fcntl.h>
#include <time.h>
#include <errno.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sock.h>

#define MAXSIZE 64

void usage(const char *info)
{
 printf("Usage: %s <ip> <port>\n", info);
 exit(0);
}

int main(int argc, char *argv[])
{
 if (argc != 3)
  usage(argv[0]);

 int sockfd;
 char buf[MAXSIZE];
 struct sockaddr_in peeraddr;

 sockfd = Socket(PF_INET, SOCK_DGRAM, 0);

 int on=1;
 Setsockopt(sockfd, SOL_SOCKET, SO_BROADCAST, &on, sizeof on);

 bzero(&peeraddr, sizeof(peeraddr));
 peeraddr.sin_family = PF_INET;
 peeraddr.sin_port = htons(atoi(argv[2]));
 peeraddr.sin_addr.s_addr = inet_addr(argv[1]);

 strcpy(buf, "This is a multicast package!\n");

 while(1){
  sendto(sockfd, buf, MAXSIZE, 0,
   (struct sockaddr *)&peeraddr, sizeof(peeraddr));
  sleep(1);
 }

 return 0;
}