#include <stdio.h> #include <sys/socket.h> #include <sys/types.h> #include <string.h> #include <stdlib.h> #include <arpa/inet.h> #define BUFLINE 256 int main(int argc, char *argv[]){ struct sockaddr_in local; int fd, n; struct ip_mreq mc; char msg[BUFLINE + 1]; if(argc != 3){ printf("Usage: ip port\n"); return 1; } fd = socket(AF_INET, SOCK_DGRAM, 0); if(fd == -1){ perror("socket()"); return 1; } memset(&local, 0, sizeof(local)); local.sin_port = htons(atoi(argv[2])); local.sin_addr.s_addr = htonl(INADDR_ANY); if(inet_pton(AF_INET, "192.168.30.61", &mc.imr_interface) <= 0){//my ip perror("inet_pton"); return 1; } if(inet_pton(AF_INET, argv[1], &mc.imr_multiaddr) <= 0){//multi addr perror("inet_pton()"); return 1; } printf("ip: %s\n", inet_ntoa(mc.imr_multiaddr)); fflush(stdout); if(setsockopt(fd, IPPROTO_IP, IP_ADD_MEMBERSHIP, &mc, sizeof(mc)) < 0){ perror("setsockopt"); return 1; } if(bind(fd, (struct sockaddr*)&local, sizeof(local)) == -1){ perror("bind"); return 1; } n = read(fd, msg, BUFLINE); if(n < 0){ fprintf(stderr, "read"); return 1; }else{ msg[n - 1] = 0; printf("%s\n", msg); } return 0; }运行:./mclient 224.0.4.5 123
224.0.4.5是组播地址。