Function ng_iface_bpftap

freebsd/netgraph/ng_iface.c:418–426

* Flash a packet by the BPF (requires prepending 4 byte AF header) * Note the phoney mbuf; this is OK because BPF treats it read-only. */

 * Note the phoney mbuf; this is OK because BPF treats it read-only.
 */
static void
ng_iface_bpftap(struct ifnet *ifp, struct mbuf *m, sa_family_t family)
{
	KASSERT(family != AF_UNSPEC, ("%s: family=AF_UNSPEC", __func__));
	if (bpf_peers_present(ifp->if_bpf)) {
		int32_t family4 = (int32_t)family;
		bpf_mtap2(ifp->if_bpf, &family4, sizeof(family4), m);
	}
}

/*
 * This routine does actual delivery of the packet into the