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| /*
* listener.c -- joins a multicast group and echoes all data it receives from
*the group to its stdout...
*
* Antony Courtney,25/11/94
* Modified by: Frdric Bastien (25/03/04)
* to compile without warning and work correctly
*/
#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 <stdlib.h>
#define HELLO_PORT 22600
#define HELLO_GROUP "224.192.32.19"
#define MSGBUFSIZE 800
main(int argc, char *argv[])
{
struct sockaddr_in addr;
int fd, nbytes,addrlen;
struct ip_mreq mreq;
char msgbuf[MSGBUFSIZE];
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) {
addrlen=sizeof(addr);
if ((nbytes=recvfrom(fd,msgbuf,MSGBUFSIZE,0,
(struct sockaddr *) &addr,&addrlen)) < 0) {
perror("recvfrom");
exit(1);
}
msgbuf[nbytes] = 0x00; // null terminate before printing
puts(msgbuf);
}
} |
