linux多播程序（无需修改，可在x87平台和arm平台上面运行）

#include <stdio.h> #include <sys/socket.h> #include <errno.h> #include <unistd.h> #include <string.h> #include <stdlib.h> #include <netdb.h> char *host_name = "224.0.1.129"; int port = 6789; int main(int argc, char **argv) { int socketfd; struct sockaddr_in sin,sinclient; struct ip_mreq command; int loop = 1, iter = 0, sin_len; struct hostent *server_host_name; char message[256]; if ((server_host_name = gethostbyname(host_name)) == 0) { perror("gethostbyname"); exit(EXIT_FAILURE); } /*open socket*/ socketfd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP); if (-1 == socketfd) { perror("Opening socket"); exit(EXIT_FAILURE); } loop = 1;/*allow address reuse*/ if (setsockopt(socketfd, SOL_SOCKET, SO_REUSEADDR, &loop, sizeof(loop)) < 0) { perror("setsockopt: SO_REUSEADDR"); exit(EXIT_FAILURE); } /*bind socket*/ /*need INADDR_ANY to allow receipt of multi-cast and uni-cast messages*/ memset(&sin, 0, sizeof(sin)); sin.sin_family = AF_INET; sin.sin_addr.s_addr = htonl(INADDR_ANY); sin.sin_port = htons(port); if (bind(socketfd, (struct sockaddr *)&sin, sizeof(sin)) < 0) { perror("bind"); exit(EXIT_FAILURE); } loop = 1; if (setsockopt(socketfd, IPPROTO_IP, IP_MULTICAST_LOOP, &loop, sizeof(loop)) < 0) { perror("setsockopt: IP_MULTICAST_LOOP"); exit(EXIT_FAILURE); } command.imr_multiaddr.s_addr = inet_addr("224.0.1.129"); command.imr_interface.s_addr = inet_addr(argv[1]); if (command.imr_multiaddr.s_addr == -1) { perror("224.0.1.129 not a legal multicast address."); exit(EXIT_FAILURE); } if(setsockopt(socketfd,IPPROTO_IP,IP_MULTICAST_IF,&command.imr_interface.s_addr,sizeof(struct in_addr))<0) { perror("failed to enable multi-cast on the interface"); exit(EXIT_FAILURE); } if (setsockopt(socketfd, IPPROTO_IP, IP_ADD_MEMBERSHIP, &command, sizeof(struct ip_mreq)) < 0) { perror("setsockopt: IP ADD_MEMBERSHIP"); exit(EXIT_FAILURE); } /* if( setsockopt(socketfd, IPPROTO_IP, IP_MULTICAST_TTL, &loop, sizeof(int)) < 0) { perror("failed to set the multi-cast time-to-live"); exit(EXIT_FAILURE); }*/ //starting Mcast transmit... while(1) { sinclient.sin_family = AF_INET; sinclient.sin_addr.s_addr = inet_addr("224.0.1.129"); sinclient.sin_port = htons(port); if (sendto(socketfd, "test from broadcast", sizeof("test from broadcast"), 0,(struct sockaddr *)&sinclient, sizeof(sinclient)) < 0) { perror("sendto"); exit(EXIT_FAILURE); } sleep(2); } exit(EXIT_SUCCESS); }