[buug] FreeBSD Multicast
Abhay Kumar Srivastava
abhay_srivastava at infosys.com
Thu Sep 18 06:46:54 PDT 2003
I am trying to multicast a message from FreeBSD machine. This code works
on a machine FreeBSD 4.7 but gives an error " route not found"
on 2 another machines FreeBSD 4.2. while sending the message to Class D
Address. I have changed the /etc/hosts of all the machine to incorporate
the same Class D address.
Please tell me what needs to be done.
Regards,
Abhay
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <stdio.h>
#include <unistd.h> /* close */
#define SERVER_PORT 1500
#define MAX_MSG 100
int main(int argc, char *argv[]) {
int sd, rc, i;
unsigned char ttl = 1;
struct sockaddr_in cliAddr, servAddr;
struct hostent *h;
if(argc<3) {
printf("usage %s <mgroup> <data1> <data2> ... <dataN>\n",argv[0]);
exit(1);
}
h = gethostbyname(argv[1]);
if(h==NULL) {
printf("%s : unknown host '%s'\n",argv[0],argv[2]);
exit(1);
}
servAddr.sin_family = h->h_addrtype;
memcpy((char *) &servAddr.sin_addr.s_addr,
h->h_addr_list[0],h->h_length);
servAddr.sin_port = htons(SERVER_PORT);
/* check if dest address is multicast */
if(!IN_MULTICAST(ntohl(servAddr.sin_addr.s_addr))) {
printf("%s : given address '%s' is not multicast \n",argv[0],
inet_ntoa(servAddr.sin_addr));
exit(1);
}
/* create socket */
sd = socket(AF_INET,SOCK_DGRAM,0);
if (sd<0) {
printf("%s : cannot open socket\n",argv[0]);
exit(1);
}
/* bind any port number */
cliAddr.sin_family = AF_INET;
cliAddr.sin_addr.s_addr = htonl(INADDR_ANY);
cliAddr.sin_port = htons(0);
if(bind(sd,(struct sockaddr *) &cliAddr,sizeof(cliAddr))<0) {
perror("bind");
exit(1);
}
if(setsockopt(sd,IPPROTO_IP,IP_MULTICAST_TTL, &ttl,sizeof(ttl))<0) {
printf("%s : cannot set ttl = %d \n",argv[0],ttl);
exit(1);
}
printf("%s : sending data on multicast group '%s' (%s)\n",argv[0],
h->h_name,inet_ntoa(*(struct in_addr *)
h->h_addr_list[0]));
/* send data */
for(i=2;i<argc;i++) {
rc = sendto(sd,argv[i],strlen(argv[i])+1,0,
(struct sockaddr *) &servAddr,
sizeof(servAddr));
if (rc<0) {
printf("%s : cannot send data %d\n",argv[0],i-1);
close(sd);
exit(1);
}
}/* end for */
/* close socket and exit */
close(sd);
exit(0);
}
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