npf_socket_lookup_rid
int npf_socket_lookup_rid(npf_cache_t *, get_rid_t, uint32_t *, int);
if (npf_socket_lookup_rid(npc, kauth_cred_getegid, &sock_gid, dir) == -1)
if (npf_socket_lookup_rid(npc, kauth_cred_geteuid, &sock_uid, dir) == -1)