multicast 的问题

发布于 2022-07-24 20:18:49 字数 5174 浏览 11 评论 1

#include <stdio.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <net/if.h>
#include <netinet/in.h>
#include <string.h>

void mcast_join(int sockfd)
{
      struct ip_mreq req;
      req.imr_interface.s_addr=INADDR_ANY;
      inet_aton("224.2.2.2",&req.imr_multiaddr);
      setsockopt(sockfd,IPPROTO_IP,IP_ADD_MEMBERSHIP,&req,sizeof(req));
}

char *sock_ntop(const struct sockaddr *sa,socklen_t len)
{
char portstr[8];
static char str[128];

struct sockaddr_in *sin = (struct sockaddr_in *) sa;

      if (inet_ntop(AF_INET, &sin->sin_addr, str, sizeof(str)) == NULL)
         return (NULL);
      if (ntohs(sin->sin_port) != 0)
      {
         snprintf(portstr, sizeof(portstr), ":%d",ntohs(sin->sin_port));
         strcat(str, portstr);
      }
      return (str);

}

int main()
{
      int recvfd;
      int opt;
      socklen_t len;
      struct sockaddr_in sockclient,sockrecv;
      int ret;
      char line[100];

      bzero(&sockrecv,sizeof(struct sockaddr_in));
      sockrecv.sin_family=AF_INET;
      sockrecv.sin_port = htons(888;
      sockrecv.sin_addr.s_addr=htonl(INADDR_ANY);

// inet_pton(AF_INET, "0.0.0.15", &sockrecv.sin_addr);

      recvfd = socket(AF_INET , SOCK_DGRAM, 0);
      opt=1;
      setsockopt(recvfd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt));

      len=sizeof(struct sockaddr_in);
      bind(recvfd,(struct sockaddr*)&sockrecv,len);
      printf("%dn",recvfd);

mcast_join(recvfd);
// setsockopt(recvfd,IPPROTO_IP,IP_MULTICAST_LOOP,&opt,sizeof(opt));

      while((ret=recvfrom(recvfd,line,100,0,(struct sockaddr *)&sockclient,&len))>0)
      {
            line[ret]='';
            printf("from %s : %sn",sock_ntop((struct sockaddr *)&sockclient,len),line);
      }
      close(recvfd);
}

int main()
{
      int ret;
      char line[100]="multicast send";
      struct sockaddr_in socksend;
      int sockfd;

      bzero(&socksend,sizeof(struct sockaddr_in));
      socksend.sin_family=AF_INET;
      socksend.sin_port = htons(888;
      inet_pton(AF_INET, "224.2.2.2", &socksend.sin_addr);

sockfd=socket(AF_INET,SOCK_DGRAM,0);

      printf("%dn",sockfd);
      ret=sendto(sockfd,line,strlen(line),0,(struct sockaddr *)&socksend,sizeof(struct sockaddr_in));
      printf("%dn";
}