Hello all,
I am fairly new to C, and I am trying to write a client/server API
for multicast. I have come across the script below, but for some
reason, the server does not get any of the multicast traffic from the
client, so I am afraid that somewhere there might be a mistake in the
script. Would anybody care to have a quick check ? Never mind the
French comments, I ŽborrowedŽ the script from a French website...
// Server code
#include <stdio.h>
#include <string.h>
#include <netinet/in.h>
#include <unistd.h>
#include <sys/socket.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#define GROUP "239.137.194.111"
#define PORT 55555
#define TAILLE 512
int main()
{
int sockfd;
struct sockaddr_in servaddr;
struct ip_mreq imr;
int len_serv;
char message_recu[TAILLE];
memset(message_recu, 0, TAILLE);
len_serv = sizeof(servaddr);
sockfd = socket(AF_INET, SOCK_DGRAM, 0);
if(sockfd < 0)
{
perror("Problemes lors de l'ouverture de la socket ");
exit(1);
}
memset(&servaddr, 0, len_serv);
servaddr.sin_family = AF_INET;
servaddr.sin_port = htons(PORT);
servaddr.sin_addr.s_addr = INADDR_ANY;
if(bind(sockfd, (struct sockaddr *)&servaddr, len_serv) < 0)
{
perror("Problemes lors de l'association de la socket a un port ");
exit(1);
}
inet_aton(GROUP, &(imr.imr_multiaddr));
imr.imr_interface.s_addr = INADDR_ANY;
if(setsockopt(sockfd, IPPROTO_IP, IP_ADD_MEMBERSHIP, &imr, sizeof(imr))
< 0)
{
perror("Problemes lors de la demande de JOIN ");
exit(1);
}
if(recvfrom(sockfd, message_recu, TAILLE, 0, (struct sockaddr
*)&servaddr, &len_serv) < 0)
{
perror("Problemes lors de la lecture d'une donnee ");
exit(1);
}
printf("%s\n", message_recu);
close(sockfd);
}
// Client Code
#include <stdio.h>
#include <string.h>
#include <netinet/in.h>
#include <unistd.h>
#include <sys/socket.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#define GROUP "239.137.194.111"
#define PORT 55555
#define TAILLE 512
int main()
{
int sockfd;
struct sockaddr_in servaddr;
char message[TAILLE];
memset(message, 0, TAILLE);
sprintf(message, "Coucou");
sockfd = socket(AF_INET, SOCK_DGRAM, 0);
if(sockfd < 0)
{
perror("Problemes lors de l'ouverture de la socket ");
exit(1);
}
memset(&servaddr, 0, sizeof(servaddr));
servaddr.sin_family = AF_INET;
servaddr.sin_port = htons(PORT);
inet_aton(GROUP, &(servaddr.sin_addr));
if(sendto(sockfd, message, strlen(message), 0, (struct sockaddr
*)&servaddr, sizeof(servaddr)) < 0)
{
perror("Problemes lors de l'envoi du message ");
exit(1);
}
}
Your help is greatly appreciated.
Regards,
GP
