linux组播编程一个简单的例子

废话少说，直接上程序

接收端程序如下：

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <time.h>
#include <string.h>
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#define HELLO_PORT 1234
#define HELLO_GROUP "224.0.0.2"
#define MSGBUFSIZE 256
int main(int argc, char *argv[])
{
struct sockaddr_in addr;
int fd, nbytes,addrlen;
struct ip_mreq mreq;
char msgbuf[MSGBUFSIZE];

int i=0;
u_int yes=1; /*** MODIFICATION TO ORIGINAL */
/* create what looks like an ordinary UDP socket */
if ((fd=socket(AF_INET,SOCK_DGRAM,0)) < 0)
{
perror("socket");
exit(1);
}
/**** MODIFICATION TO ORIGINAL */
/* allow multiple sockets to use the same PORT number */
if (setsockopt(fd,SOL_SOCKET,SO_REUSEADDR,&yes,sizeof(yes)) < 0)
{
perror("Reusing ADDR failed");
exit(1);
}
/*** END OF MODIFICATION TO ORIGINAL */
/* set up destination address */
memset(&addr,0,sizeof(addr));
addr.sin_family=AF_INET;
addr.sin_addr.s_addr=htonl(INADDR_ANY); /* N.B.: differs from sender */
addr.sin_port=htons(HELLO_PORT);
/* bind to receive address */
if (bind(fd,(struct sockaddr *) &addr,sizeof(addr)) < 0)
{
perror("bind");
exit(1);
}
/* use setsockopt() to request that the kernel join a multicast group */
mreq.imr_multiaddr.s_addr=inet_addr(HELLO_GROUP);
mreq.imr_interface.s_addr=htonl(INADDR_ANY);
if (setsockopt(fd,IPPROTO_IP,IP_ADD_MEMBERSHIP,&mreq,sizeof(mreq)) < 0)
{
perror("setsockopt");
exit(1);
}
/* now just enter a read-print loop */
while (1)
{
//ssize_t recvfrom(int s, void *buf, size_t len, int flags, struct sockaddr *from, socklen_t *fromlen);
addrlen=sizeof(addr);
if ((nbytes=recvfrom(fd, msgbuf, MSGBUFSIZE, 0, (struct sockaddr *) &addr, (socklen_t *)&addrlen)) < 0)
{
perror("recvfrom");
exit(1);
}
printf("nbytes=%d\n",nbytes);
puts(msgbuf);
}
return 0;
}

//如果运行rcv程序的时候出现setopt：no device 执行下面语句即可

// route add -net 225.18.1.7 netmask 225.18.1.7 eth0

发送端程序如下：
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <time.h>
#include <string.h>
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#define HELLO_PORT 1234
#define HELLO_GROUP "224.0.0.2"

int main(int argc, char *argv[])
{
struct sockaddr_in addr;
int fd, cnt;
struct ip_mreq mreq;
char *message="Hello, World!";
/* create what looks like an ordinary UDP socket */
if ((fd=socket(AF_INET,SOCK_DGRAM,0)) < 0)
{
perror("socket");
exit(1);
}
/* set up destination address */
memset(&addr,0,sizeof(addr));
addr.sin_family=AF_INET;
addr.sin_addr.s_addr=inet_addr(HELLO_GROUP);
addr.sin_port=htons(HELLO_PORT);
/* now just sendto() our destination! */
while (1)
{
if (sendto(fd,message, strlen(message), 0, (struct sockaddr *) &addr, sizeof(addr)) < 0)
{
perror("sendto");
exit(1);
}
sleep(1);
}
return 0;
}