ip_deliver
ip_deliver(&m, &hlen, prot, af, 0, NULL);
nxt = ip_deliver(mp, offp, nxt, AF_INET, 1, ns);
nxt = ip_deliver(&m, &off, nxt, AF_INET, 0, NULL);
int ip_deliver(struct mbuf **, int *, int, int, int, struct netstack *);
nxt = ip_deliver(mp, offp, nxt, AF_INET6, 1, ns);
nxt = ip_deliver(&m, &off, nxt, AF_INET6, 0, NULL);