ifa_ifwithnet_psref
struct ifaddr *ifa_ifwithnet_psref(const struct sockaddr *, struct psref *);
ifa = ifa_ifwithnet_psref(gateway, psref);
ifa = ifa_ifwithnet_psref(info->rti_info[RTAX_IFP], psref);
if ((ifa = ifa_ifwithnet_psref(gateway, &psref)) == NULL) {