getsourcefilter
err = getsourcefilter(s, ifindex, (struct sockaddr *)&tmpgroup,
int getsourcefilter(int, uint32_t, struct sockaddr *, socklen_t,
if (getsourcefilter(af2sock(af, s, s6), ifindex,
if (getsourcefilter(af2sock(af, s, s6), ifindex, &su.sa,