STF2IFP
ifp = STF2IFP(sc) = if_alloc(IFT_STF);
if ((STF2IFP(sc)->if_flags & IFF_UP) == 0)
if ((STF2IFP(sc)->if_flags & IFF_LINK0) != 0)
if (stf_getsrcifa6(STF2IFP(sc), &addr6, &mask6) != 0)
if (sc && (STF2IFP(sc)->if_flags & IFF_LINK2) == 0 && inifp) {
if (sc == NULL || (STF2IFP(sc)->if_flags & IFF_UP) == 0) {
ifp = STF2IFP(sc);