in_lookup_multi
inm = in_lookup_multi(igmp->igmp_group, ifp);
inm = in_lookup_multi(igmp->igmp_group, ifp);
ingroup = in_lookup_multi(addr, ifp) != NULL;
ingroup = in_lookup_multi(addr, ifp) != NULL;
inm = in_lookup_multi(*ap, ifp);
struct in_multi *in_lookup_multi(struct in_addr, struct ifnet *);