memset (&mreq, 0, sizeof (mreq));
mreq.imr_multiaddr.s_addr = addr->sin_addr.s_addr;
mreq.imr_address.s_addr = ntohl (INADDR_ANY);
memset (&mreq, 0, sizeof (mreq));
mreq.imr_multiaddr.s_addr = addr->sin_addr.s_addr;
mreq.imr_address.s_addr = ntohl (INADDR_ANY);