Function ether_demux

freebsd/net/if_ethersubr.c:841–944

* Upper layer processing for a received Ethernet packet. */

 * Upper layer processing for a received Ethernet packet.
 */
void
ether_demux(struct ifnet *ifp, struct mbuf *m)
{
	struct ether_header *eh;
	int i, isr;
	u_short ether_type;

	NET_EPOCH_ASSERT();
	KASSERT(ifp != NULL, ("%s: NULL interface pointer", __func__));

	/* Do not grab PROMISC frames in case we are re-entered. */
	if (PFIL_HOOKED_IN(V_link_pfil_head) && !(m->m_flags & M_PROMISC)) {
		i = pfil_run_hooks(V_link_pfil_head, &m, ifp, PFIL_IN, NULL);
		if (i != 0 || m == NULL)
			return;
	}

	eh = mtod(m, struct ether_header *);
	ether_type = ntohs(eh->ether_type);

	/*
	 * If this frame has a VLAN tag other than 0, call vlan_input()
	 * if its module is loaded. Otherwise, drop.
	 */
	if ((m->m_flags & M_VLANTAG) &&
	    EVL_VLANOFTAG(m->m_pkthdr.ether_vtag) != 0) {
		if (ifp->if_vlantrunk == NULL) {
			if_inc_counter(ifp, IFCOUNTER_NOPROTO, 1);
			m_freem(m);
			return;
		}
		KASSERT(vlan_input_p != NULL,("%s: VLAN not loaded!",
		    __func__));
		/* Clear before possibly re-entering ether_input(). */
		m->m_flags &= ~M_PROMISC;
		(*vlan_input_p)(ifp, m);
		return;
	}

	/*
	 * Pass promiscuously received frames to the upper layer if the user
	 * requested this by setting IFF_PPROMISC. Otherwise, drop them.
	 */
	if ((ifp->if_flags & IFF_PPROMISC) == 0 && (m->m_flags & M_PROMISC)) {
		m_freem(m);
		return;
	}

	/*
	 * Reset layer specific mbuf flags to avoid confusing upper layers.
	 * Strip off Ethernet header.
	 */
	m->m_flags &= ~M_VLANTAG;
	m_clrprotoflags(m);
	m_adj(m, ETHER_HDR_LEN);

	/*
	 * Dispatch frame to upper layer.