| /*
* listen.c - An IP multicast client */
#include
#include
#include
#include
#include
#include
#include
char * host_name = \"224.0.0.1\";
/* 多播IP地址 */
int port = 6789;
int main(void)
{
struct ip_mreq command;
int loop = 1;
/* 多播循环 */
int iter = 0;
int sin_len;
char message[256];
int socket_descriptor;
struct sockaddr_in sin;
struct hostent *server_host_name;
if((server_host_name = gethostbyname(host_name)) == 0)
{
perror(\"gethostbyname\");
exit(EXIT_FAILURE);
}
/*bzero(&sin, sizeof(sin));*/
memset(&sin, 0, sizeof(sin));
sin.sin_family = AF_INET;
sin.sin_addr.s_addr = htonl(INADDR_ANY);
sin.sin_port = htons(port);
if((socket_descriptor = socket(PF_INET, SOCK_DGRAM, 0)) == -1)
{ perror(\"socket\");
exit(EXIT_FAILURE);
}
/* 调用bind之前，设置套接口选项启用多播IP支持*/
loop = 1;
if(setsockopt(socket_descriptor,
SOL_SOCKET, SO_REUSEADDR,
&loop, sizeof(loop)) < 0)
{
perror(\"setsockopt:SO_REUSEADDR\");
exit(EXIT_FAILURE);
}
if(bind(socket_descriptor,
(struct sockaddr *)&sin, sizeof(sin)) < 0)
{
perror(\"bind\");
exit(EXIT_FAILURE);
}
/* 在同一个主机上进行广播设置套接口，
作用是方便单个开发系统上测试多播IP广播 */
loop = 1;
if(setsockopt(socket_descriptor,
IPPROTO_IP, IP_MULTICAST_LOOP,
&loop, sizeof(loop)) < 0)
{
perror(\"setsockopt:IP_MULTICAST_LOOP\");
exit(EXIT_FAILURE);
}
/* 加入一个广播组。进一步告诉Linux内核，
特定的套接口即将接受广播数据*/
command.imr_multiaddr.s_addr = inet_addr(\"224.0.0.1\");
command.imr_interface.s_addr = htonl(INADDR_ANY);
if(command.imr_multiaddr.s_addr == -1)
{
perror(\"224.0.0.1 not a legal multicast address\");
exit(EXIT_FAILURE);
}
if (setsockopt(socket_descriptor, IPPROTO_IP, IP_ADD_MEMBERSHIP,
&command, sizeof(command)) < 0)
{
perror(\"setsockopt:IP_ADD_MEMBERSHIP\");
}
while(iter++ < 8)
{
sin_len = sizeof(sin);
if(recvfrom(socket_descriptor, message, 256, 0,
(struct sockaddr *)&sin, &sin_len) == -1) {
perror(\"recvfrom\");
}
printf(\"Response #%-2d from server: %s\\n\", iter, message);
sleep(2); }
/* 接受8个广播后退出 */
if(setsockopt(socket_descriptor, IPPROTO_IP, IP_DROP_MEMBERSHIP,
&command, sizeof(command)) < 0) {
perror(\"setsockopt:IP_DROP_MEMBERSHIP\");
}
close(socket_descriptor);
exit(EXIT_SUCCESS);} |