in_lookupmulti
inm = in_lookupmulti(&igmp->igmp_group, ifp);
inm = in_lookupmulti(&igmp->igmp_group, ifp);
inm = in_lookupmulti(addr, ifp);
inm = in_lookupmulti(addr, ifp);
inm = in_lookupmulti(addr, ifp);
struct in_multi *in_lookupmulti(const struct in_addr *, struct ifnet *);