if_getifaddr
mac = LLADDR((struct sockaddr_dl *)if_getifaddr(sc->ifp)->ifa_addr);
if (if_getifaddr(ifp) == NULL || if_getifaddr(hn_ifp) == NULL)
ifa = if_getifaddr(ip_dev);
struct ifaddr * if_getifaddr(const if_t ifp);
if_getifaddr(attr->ndev) != NULL)