main.c

#include	"unp.h"

void	recv_all(int, socklen_t);
void	send_all(int, SA *, socklen_t);

int
main(int argc, char **argv)
{
	int					sendfd, recvfd;
	const int			on = 1;
	socklen_t			salen;
	struct sockaddr		*sasend, *sarecv;

	if (argc != 3)
		err_quit("usage: sendrecv <IP-multicast-address> <port#>");

	sendfd = Udp_client(argv[1], argv[2], (void **) &sasend, &salen);

	recvfd = Socket(sasend->sa_family, SOCK_DGRAM, 0);

	Setsockopt(recvfd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on));

	sarecv = Malloc(salen);
	memcpy(sarecv, sasend, salen);
	Bind(recvfd, sarecv, salen);

	Mcast_join(recvfd, sasend, salen, NULL, 0);
	Mcast_set_loop(sendfd, 0);

	if (Fork() == 0)
		recv_all(recvfd, salen);		/* child -> receives */

	send_all(sendfd, sasend, salen);	/* parent -> sends */
}