int ttl;
socklen_t len = sizeof (ttl);
if (!getsockopt (rtp_fd, SOL_IP, IP_MULTICAST_TTL, &ttl, &len))
setsockopt (fd, SOL_IP, IP_MULTICAST_TTL, &ttl, len);
int ttl;
socklen_t len = sizeof (ttl);
if (!getsockopt (rtp_fd, SOL_IP, IP_MULTICAST_TTL, &ttl, &len))
setsockopt (fd, SOL_IP, IP_MULTICAST_TTL, &ttl, len);