xref: /src/sys/net/if_vlan.c

/*	$NetBSD: if_vlan.c,v 1.11 2000/10/03 23:50:52 thorpej Exp $	*/

/*-
 * Copyright (c) 2000 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Andrew Doran, and by Jason R. Thorpe of Zembu Labs, Inc.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the NetBSD
 *	Foundation, Inc. and its contributors.
 * 4. Neither the name of The NetBSD Foundation nor the names of its
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

/*
 * Copyright 1998 Massachusetts Institute of Technology
 *
 * Permission to use, copy, modify, and distribute this software and
 * its documentation for any purpose and without fee is hereby
 * granted, provided that both the above copyright notice and this
 * permission notice appear in all copies, that both the above
 * copyright notice and this permission notice appear in all
 * supporting documentation, and that the name of M.I.T. not be used
 * in advertising or publicity pertaining to distribution of the
 * software without specific, written prior permission.  M.I.T. makes
 * no representations about the suitability of this software for any
 * purpose.  It is provided "as is" without express or implied
 * warranty.
 *
 * THIS SOFTWARE IS PROVIDED BY M.I.T. ``AS IS''.  M.I.T. DISCLAIMS
 * ALL EXPRESS OR IMPLIED WARRANTIES WITH REGARD TO THIS SOFTWARE,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT
 * SHALL M.I.T. BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * from FreeBSD: if_vlan.c,v 1.16 2000/03/26 15:21:40 charnier Exp
 * via OpenBSD: if_vlan.c,v 1.4 2000/05/15 19:15:00 chris Exp
 */

/*
 * if_vlan.c - pseudo-device driver for IEEE 802.1Q virtual LANs.  Might be
 * extended some day to also handle IEEE 802.1P priority tagging.  This is
 * sort of sneaky in the implementation, since we need to pretend to be
 * enough of an Ethernet implementation to make ARP work.  The way we do
 * this is by telling everyone that we are an Ethernet interface, and then
 * catch the packets that ether_output() left on our output queue when it
 * calls if_start(), rewrite them for use by the real outgoing interface,
 * and ask it to send them.
 *
 * TODO:
 *
 *	- Need some way to notify vlan interfaces when the parent
 *	  interface changes MTU.
 *
 *	- Need to notify VLANs when an interface detaches.
 *
 *	- Need a way to facilitate parent interfaces that can do
 *	  tag insertion and/or extraction in hardware.
 *
 *	- Need to make promiscuous mode work.
 */

#include "opt_inet.h"
#include "bpfilter.h"

#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/mbuf.h>
#include <sys/queue.h>
#include <sys/socket.h>
#include <sys/sockio.h>
#include <sys/systm.h>
#include <sys/proc.h>

#if NBPFILTER > 0
#include <net/bpf.h>
#endif
#include <net/if.h>
#include <net/if_dl.h>
#include <net/if_types.h>
#include <net/if_ether.h>
#include <net/if_vlanvar.h>

#ifdef INET
#include <netinet/in.h>
#include <netinet/if_inarp.h>
#endif

extern struct	ifaddr **ifnet_addrs;	/* XXX if.c */

struct vlan_mc_entry {
	LIST_ENTRY(vlan_mc_entry)	mc_entries;
	/*
	 * A key to identify this entry.  The mc_addr below can't be
	 * used since multiple sockaddr may mapped into the same
	 * ether_multi (e.g., AF_UNSPEC).
	 */
	union {
		struct ether_multi	*mcu_enm;
	} mc_u;
	struct sockaddr_storage		mc_addr;
};

#define	mc_enm		mc_u.mcu_enm

struct ifvlan {
	union {
		struct ethercom ifvu_ec;
	} ifv_u;
	struct ifnet *ifv_p;	/* parent interface of this vlan */
	struct ifv_linkmib {
		const struct vlan_multisw *ifvm_msw;
		int	ifvm_encaplen;	/* encapsulation length */
		int	ifvm_mtufudge;	/* MTU fudged by this much */
		int	ifvm_mintu;	/* min transmission unit */
		u_int16_t ifvm_proto;	/* encapsulation ethertype */
		u_int16_t ifvm_tag;	/* tag to apply on packets */
	} ifv_mib;
	LIST_HEAD(__vlan_mchead, vlan_mc_entry) ifv_mc_listhead;
	LIST_ENTRY(ifvlan) ifv_list;
};

#define	ifv_ec		ifv_u.ifvu_ec

#define	ifv_if		ifv_ec.ec_if

#define	ifv_msw		ifv_mib.ifvm_msw
#define	ifv_encaplen	ifv_mib.ifvm_encaplen
#define	ifv_mtufudge	ifv_mib.ifvm_mtufudge
#define	ifv_mintu	ifv_mib.ifvm_mintu
#define	ifv_tag		ifv_mib.ifvm_tag

struct vlan_multisw {
	int	(*vmsw_addmulti)(struct ifvlan *, struct ifreq *);
	int	(*vmsw_delmulti)(struct ifvlan *, struct ifreq *);
	void	(*vmsw_purgemulti)(struct ifvlan *);
};

static int	vlan_ether_addmulti(struct ifvlan *, struct ifreq *);
static int	vlan_ether_delmulti(struct ifvlan *, struct ifreq *);
static void	vlan_ether_purgemulti(struct ifvlan *);

const struct vlan_multisw vlan_ether_multisw = {
	vlan_ether_addmulti,
	vlan_ether_delmulti,
	vlan_ether_purgemulti,
};

static int	vlan_clone_create(struct if_clone *, int);
static void	vlan_clone_destroy(struct ifnet *);
static int	vlan_config(struct ifvlan *, struct ifnet *);
static int	vlan_ioctl(struct ifnet *, u_long, caddr_t);
static void	vlan_start(struct ifnet *);
static void	vlan_unconfig(struct ifnet *);

void		vlanattach(int);

/* XXX This should be a hash table with the tag as the basis of the key. */
static LIST_HEAD(, ifvlan) ifv_list;

struct if_clone vlan_cloner =
    IF_CLONE_INITIALIZER("vlan", vlan_clone_create, vlan_clone_destroy);

void
vlanattach(int n)
{

	LIST_INIT(&ifv_list);
	if_clone_attach(&vlan_cloner);
}

static int
vlan_clone_create(struct if_clone *ifc, int unit)
{
	struct ifvlan *ifv;
	struct ifnet *ifp;
	int s;

	ifv = malloc(sizeof(struct ifvlan), M_DEVBUF, M_WAITOK);
	memset(ifv, 0, sizeof(struct ifvlan));
	ifp = &ifv->ifv_ec.ec_if;
	LIST_INIT(&ifv->ifv_mc_listhead);

	s = splnet();
	LIST_INSERT_HEAD(&ifv_list, ifv, ifv_list);
	splx(s);

	sprintf(ifp->if_xname, "%s%d", ifc->ifc_name, unit);
	ifp->if_softc = ifv;
	ifp->if_flags = IFF_BROADCAST | IFF_SIMPLEX | IFF_MULTICAST;
	ifp->if_start = vlan_start;
	ifp->if_ioctl = vlan_ioctl;

	if_attach(ifp);

	return (0);
}

static void
vlan_clone_destroy(struct ifnet *ifp)
{
	struct ifvlan *ifv = ifp->if_softc;
	int s;

	s = splnet();
	LIST_REMOVE(ifv, ifv_list);
	vlan_unconfig(ifp);
	splx(s);

#if NBPFILTER > 0
	bpfdetach(ifp);
#endif
	ether_ifdetach(ifp);
	if_detach(ifp);
	free(ifv, M_DEVBUF);
}

/*
 * Configure a VLAN interface.  Must be called at splnet().
 */
static int
vlan_config(struct ifvlan *ifv, struct ifnet *p)
{
	struct ifnet *ifp = &ifv->ifv_if;
	int error;

	if (ifv->ifv_p != NULL)
		return (EBUSY);

	switch (p->if_type) {
	case IFT_ETHER:
	    {
		struct ethercom *ec = (void *) p;

		ifv->ifv_msw = &vlan_ether_multisw;
		ifv->ifv_encaplen = ETHER_VLAN_ENCAP_LEN;
		ifv->ifv_mintu = ETHERMIN;

		/*
		 * If the parent supports the VLAN_MTU capability,
		 * i.e. can Tx/Rx larger than ETHER_MAX_LEN frames,
		 * enable it.
		 */
		if (ec->ec_nvlans++ == 0 &&
		    (ec->ec_capabilities & ETHERCAP_VLAN_MTU) != 0) {
			/*
			 * Enable Tx/Rx of VLAN-sized frames.
			 */
			ec->ec_capenable |= ETHERCAP_VLAN_MTU;
			if (p->if_flags & IFF_UP) {
				struct ifreq ifr;

				ifr.ifr_flags = p->if_flags;
				error = (*p->if_ioctl)(p, SIOCSIFFLAGS,
				    (caddr_t) &ifr);
				if (error) {
					if (ec->ec_nvlans-- == 1)
						ec->ec_capenable &=
						    ~ETHERCAP_VLAN_MTU;
					return (error);
				}
			}
			ifv->ifv_mtufudge = 0;
		} else if ((ec->ec_capabilities & ETHERCAP_VLAN_MTU) == 0) {
			/*
			 * Fudge the MTU by the encapsulation size.  This
			 * makes us incompatible with strictly compliant
			 * 802.1Q implementations, but allows us to use
			 * the feature with other NetBSD implementations,
			 * which might still be useful.
			 */
			ifv->ifv_mtufudge = ifv->ifv_encaplen;
		}

		/*
		 * We inherit the parent's Ethernet address.
		 */
		ether_ifattach(ifp, LLADDR(p->if_sadl));
		ifp->if_hdrlen = sizeof(struct ether_vlan_header); /* XXX? */
#if NBPFILTER > 0
		bpfattach(&ifp->if_bpf, ifp, DLT_EN10MB,
		    sizeof(struct ether_header));
#endif
		break;
	    }

	default:
		return (EPROTONOSUPPORT);
	}

	ifv->ifv_p = p;
	ifv->ifv_if.if_mtu = p->if_mtu - ifv->ifv_mtufudge;
	ifv->ifv_if.if_flags = p->if_flags;

	/*
	 * Inherit the if_type from the parent.  This allows us
	 * to participate in bridges of that type.
	 */
	ifv->ifv_if.if_type = p->if_type;

	return (0);
}

/*
 * Unconfigure a VLAN interface.  Must be called at splnet().
 */
static void
vlan_unconfig(struct ifnet *ifp)
{
	struct ifvlan *ifv = ifp->if_softc;

	ifv = ifp->if_softc;
	if (ifv->ifv_p == NULL)
		return;

	/*
 	 * Since the interface is being unconfigured, we need to empty the
	 * list of multicast groups that we may have joined while we were
	 * alive and remove them from the parent's list also.
	 */
	(*ifv->ifv_msw->vmsw_purgemulti)(ifv);

	/* Disconnect from parent. */
	switch (ifv->ifv_p->if_type) {
	case IFT_ETHER:
	    {
		struct ethercom *ec = (void *) ifv->ifv_p;

		if (ec->ec_nvlans-- == 1) {
			/*
			 * Disable Tx/Rx of VLAN-sized frames.
			 */
			ec->ec_capenable &= ~ETHERCAP_VLAN_MTU;
			if (ifv->ifv_p->if_flags & IFF_UP) {
				struct ifreq ifr;

				ifr.ifr_flags = ifv->ifv_p->if_flags;
				(void) (*ifv->ifv_p->if_ioctl)(ifv->ifv_p,
				    SIOCSIFFLAGS, (caddr_t) &ifr);
			}
		}

#if NBPFILTER > 0
		bpfdetach(ifp);
#endif
		ether_ifdetach(ifp);
		break;
	    }

#ifdef DIAGNOSTIC
	default:
		panic("vlan_unconfig: impossible");
#endif
	}

	ifv->ifv_p = NULL;
	ifv->ifv_if.if_mtu = 0;

	if_down(ifp);
	ifp->if_flags &= ~(IFF_UP|IFF_RUNNING);
}

/*
 * Called when a parent interface is detaching; destroy any VLAN
 * configuration for the parent interface.
 */
void
vlan_ifdetach(struct ifnet *p)
{
	struct ifvlan *ifv;
	int s;

	s = splnet();

	for (ifv = LIST_FIRST(&ifv_list); ifv != NULL;
	     ifv = LIST_NEXT(ifv, ifv_list)) {
		if (ifv->ifv_p == p)
			vlan_unconfig(&ifv->ifv_if);
	}

	splx(s);
}

static int
vlan_ioctl(struct ifnet *ifp, u_long cmd, caddr_t data)
{
	struct proc *p = curproc;	/* XXX */
	struct ifvlan *ifv = ifp->if_softc;
	struct ifaddr *ifa = (struct ifaddr *) data;
	struct ifreq *ifr = (struct ifreq *) data;
	struct ifnet *pr;
	struct vlanreq vlr;
	struct sockaddr *sa;
	int s, error = 0;

	s = splnet();

	switch (cmd) {
	case SIOCSIFADDR:
		ifp->if_flags |= IFF_UP;

		switch (ifa->ifa_addr->sa_family) {
#ifdef INET
		case AF_INET:
			arp_ifinit(ifp, ifa);
			break;
#endif
		default:
			break;
		}
		break;

	case SIOCGIFADDR:
		sa = (struct sockaddr *)&ifr->ifr_data;
		memcpy(sa->sa_data, LLADDR(ifp->if_sadl), ETHER_ADDR_LEN);
		break;

	case SIOCSIFMTU:
		if (ifv->ifv_p != NULL) {
			if (ifr->ifr_mtu >
			     (ifv->ifv_p->if_mtu - ifv->ifv_mtufudge) ||
			    ifr->ifr_mtu <
			     (ifv->ifv_mintu - ifv->ifv_mtufudge))
				error = EINVAL;
			else
				ifp->if_mtu = ifr->ifr_mtu;
		} else
			error = EINVAL;
		break;

	case SIOCSETVLAN:
		if ((error = suser(p->p_ucred, &p->p_acflag)) != 0)
			break;
		if ((error = copyin(ifr->ifr_data, &vlr, sizeof(vlr))) != 0)
			break;
		if (vlr.vlr_parent[0] == '\0') {
			vlan_unconfig(ifp);
			break;
		}
		if (vlr.vlr_tag != EVL_VLANOFTAG(vlr.vlr_tag)) {
			error = EINVAL;		 /* check for valid tag */
			break;
		}
		if ((pr = ifunit(vlr.vlr_parent)) == 0) {
			error = ENOENT;
			break;
		}
		if ((error = vlan_config(ifv, pr)) != 0)
			break;
		ifv->ifv_tag = vlr.vlr_tag;
		ifp->if_flags |= IFF_RUNNING;
		break;

	case SIOCGETVLAN:
		memset(&vlr, 0, sizeof(vlr));
		if (ifv->ifv_p != NULL) {
			snprintf(vlr.vlr_parent, sizeof(vlr.vlr_parent), "%s",
			    ifv->ifv_p->if_xname);
			vlr.vlr_tag = ifv->ifv_tag;
		}
		error = copyout(&vlr, ifr->ifr_data, sizeof(vlr));
		break;

	case SIOCSIFFLAGS:
		/*
		 * XXX We don't support promiscuous mode right now because
		 * it would require help from the underlying drivers, which
		 * hasn't been implemented.
		 */
		if ((ifr->ifr_flags & IFF_PROMISC) != 0) {
			ifp->if_flags &= ~(IFF_PROMISC);
			error = EINVAL;
		}
		break;

	case SIOCADDMULTI:
		error = (*ifv->ifv_msw->vmsw_addmulti)(ifv, ifr);
		break;

	case SIOCDELMULTI:
		error = (*ifv->ifv_msw->vmsw_delmulti)(ifv, ifr);
		break;

	default:
		error = EINVAL;
	}

	splx(s);

	return (error);
}

static int
vlan_ether_addmulti(struct ifvlan *ifv, struct ifreq *ifr)
{
	struct vlan_mc_entry *mc;
	u_int8_t addrlo[ETHER_ADDR_LEN], addrhi[ETHER_ADDR_LEN];
	int error;

	if (ifr->ifr_addr.sa_len > sizeof(struct sockaddr_storage))
		return (EINVAL);

	error = ether_addmulti(ifr, &ifv->ifv_ec);
	if (error != ENETRESET)
		return (error);

	/*
	 * This is new multicast address.  We have to tell parent
	 * about it.  Also, remember this multicast address so that
	 * we can delete them on unconfigure.
	 */
	MALLOC(mc, struct vlan_mc_entry *, sizeof(struct vlan_mc_entry),
	    M_DEVBUF, M_NOWAIT);
	if (mc == NULL) {
		error = ENOMEM;
		goto alloc_failed;
	}

	/*
	 * As ether_addmulti() returns ENETRESET, following two
	 * statement shouldn't fail.
	 */
	(void)ether_multiaddr(&ifr->ifr_addr, addrlo, addrhi);
	ETHER_LOOKUP_MULTI(addrlo, addrhi, &ifv->ifv_ec, mc->mc_enm);
	memcpy(&mc->mc_addr, &ifr->ifr_addr, ifr->ifr_addr.sa_len);
	LIST_INSERT_HEAD(&ifv->ifv_mc_listhead, mc, mc_entries);

	error = (*ifv->ifv_p->if_ioctl)(ifv->ifv_p, SIOCADDMULTI,
	    (caddr_t)ifr);
	if (error != 0)
		goto ioctl_failed;
	return (error);

 ioctl_failed:
	LIST_REMOVE(mc, mc_entries);
	FREE(mc, M_DEVBUF);
 alloc_failed:
	(void)ether_delmulti(ifr, &ifv->ifv_ec);
	return (error);
}

static int
vlan_ether_delmulti(struct ifvlan *ifv, struct ifreq *ifr)
{
	struct ether_multi *enm;
	struct vlan_mc_entry *mc;
	u_int8_t addrlo[ETHER_ADDR_LEN], addrhi[ETHER_ADDR_LEN];
	int error;

	/*
	 * Find a key to lookup vlan_mc_entry.  We have to do this
	 * before calling ether_delmulti for obvious reason.
	 */
	if ((error = ether_multiaddr(&ifr->ifr_addr, addrlo, addrhi)) != 0)
		return (error);
	ETHER_LOOKUP_MULTI(addrlo, addrhi, &ifv->ifv_ec, enm);

	error = ether_delmulti(ifr, &ifv->ifv_ec);
	if (error != ENETRESET)
		return (error);

	/* We no longer use this multicast address.  Tell parent so. */
	error = (*ifv->ifv_p->if_ioctl)(ifv->ifv_p, SIOCDELMULTI,
	    (caddr_t)ifr);
	if (error == 0) {
		/* And forget about this address. */
		for (mc = LIST_FIRST(&ifv->ifv_mc_listhead); mc != NULL;
		    mc = LIST_NEXT(mc, mc_entries)) {
			if (mc->mc_enm == enm) {
				LIST_REMOVE(mc, mc_entries);
				FREE(mc, M_DEVBUF);
				break;
			}
		}
		KASSERT(mc != NULL);
	} else
		(void)ether_addmulti(ifr, &ifv->ifv_ec);
	return (error);
}

/*
 * Delete any multicast address we have asked to add form parent
 * interface.  Called when the vlan is being unconfigured.
 */
static void
vlan_ether_purgemulti(struct ifvlan *ifv)
{
	struct ifnet *ifp = ifv->ifv_p;		/* Parent. */
	struct vlan_mc_entry *mc;
	union {
		struct ifreq ifreq;
		struct {
			char ifr_name[IFNAMSIZ];
			struct sockaddr_storage;
		} ifreq_storage;
	} ifreq;
	struct ifreq *ifr = &ifreq.ifreq;

	memcpy(ifr->ifr_name, ifp->if_xname, IFNAMSIZ);
	while ((mc = LIST_FIRST(&ifv->ifv_mc_listhead)) != NULL) {
		memcpy(&ifr->ifr_addr, &mc->mc_addr, mc->mc_addr.ss_len);
		(void)(*ifp->if_ioctl)(ifp, SIOCDELMULTI, (caddr_t)ifr);
		LIST_REMOVE(mc->mc_enm, enm_list);
		free(mc->mc_enm, M_IFMADDR);
		LIST_REMOVE(mc, mc_entries);
		FREE(mc, M_DEVBUF);
	}

	KASSERT(LIST_FIRST(&ifv->ifv_ec.ec_multiaddrs) == NULL);
}

static void
vlan_start(struct ifnet *ifp)
{
	struct ifvlan *ifv;
	struct ifnet *p;
	struct mbuf *m;

	ifv = ifp->if_softc;
	p = ifv->ifv_p;
	ifp->if_flags |= IFF_OACTIVE;

	for (;;) {
		IF_DEQUEUE(&ifp->if_snd, m);
		if (m == NULL)
			break;

#if NBPFILTER > 0
		if (ifp->if_bpf)
			bpf_mtap(ifp->if_bpf, m);
#endif

		/*
		 * XXX Should handle the case where the underlying hardware
		 * interface can do VLAN tag insertion itself.
		 */
		M_PREPEND(m, ifv->ifv_encaplen, M_DONTWAIT);
		if (m == NULL) {
			printf("%s: unable to prepend encap header",
			    ifv->ifv_p->if_xname);
			ifp->if_oerrors++;
			continue;
		}

		switch (p->if_type) {
		case IFT_ETHER:
		    {
			struct ether_vlan_header *evl;

			if (m->m_len < sizeof(struct ether_vlan_header) &&
			    (m = m_pullup(m,
			     sizeof(struct ether_vlan_header))) == NULL) {
				printf("%s: unable to pullup encap header",
				    ifv->ifv_p->if_xname);
				ifp->if_oerrors++;
				continue;
			}

			/*
			 * Transform the Ethernet header into an Ethernet
			 * header with 802.1Q encapsulation.
			 */
			memmove(mtod(m, caddr_t),
			    mtod(m, caddr_t) + ifv->ifv_encaplen,
			    sizeof(struct ether_header));
			evl = mtod(m, struct ether_vlan_header *);
			evl->evl_proto = evl->evl_encap_proto;
			evl->evl_encap_proto = htons(ETHERTYPE_VLAN);
			evl->evl_tag = htons(ifv->ifv_tag);
			break;
		    }

#ifdef DIAGNOSTIC
		default:
			panic("vlan_start: impossible");
#endif
		}

		/*
		 * Send it, precisely as the parent's output routine
		 * would have.  We are already running at splimp.
		 */
		if (IF_QFULL(&p->if_snd)) {
			IF_DROP(&p->if_snd);
			/* XXX stats */
			ifp->if_oerrors++;
			m_freem(m);
			continue;
		}

		IF_ENQUEUE(&p->if_snd, m);
		if ((p->if_flags & IFF_OACTIVE) == 0) {
			p->if_start(p);
			ifp->if_opackets++;
		}
	}

	ifp->if_flags &= ~IFF_OACTIVE;
}

/*
 * Given an Ethernet frame, find a valid vlan interface corresponding to the
 * given source interface and tag, then run the the real packet through
 * the parent's input routine.
 */
void
vlan_input(struct ifnet *ifp, struct mbuf *m)
{
	struct ifvlan *ifv;
	u_int tag;

	switch (ifp->if_type) {
	case IFT_ETHER:
	    {
		struct ether_vlan_header *evl;

		if (m->m_len < sizeof(struct ether_vlan_header) &&
		    (m = m_pullup(m,
		     sizeof(struct ether_vlan_header))) == NULL) {
			printf("%s: no memory for VLAN header, "
			    "dropping packet.\n", ifp->if_xname);
			return;
		}
		evl = mtod(m, struct ether_vlan_header *);
		KASSERT(ntohs(evl->evl_encap_proto) == ETHERTYPE_VLAN);

		tag = EVL_VLANOFTAG(ntohs(evl->evl_tag));

		/*
		 * Restore the original ethertype.  We'll remove
		 * the encapsulation after we've found the vlan
		 * interface corresponding to the tag.
		 */
		evl->evl_encap_proto = evl->evl_proto;
		break;
	    }

	default:
		tag = (u_int) -1;	/* XXX GCC */
#ifdef DIAGNOSTIC
		panic("vlan_input: impossible");
#endif
	}

	for (ifv = LIST_FIRST(&ifv_list); ifv != NULL;
	     ifv = LIST_NEXT(ifv, ifv_list))
		if (ifp == ifv->ifv_p && tag == ifv->ifv_tag)
			break;

	if (ifv == NULL ||
	    (ifv->ifv_if.if_flags & (IFF_UP|IFF_RUNNING)) !=
	     (IFF_UP|IFF_RUNNING)) {
		m_free(m);
		ifp->if_data.ifi_noproto++;
		return;
	}

	/*
	 * Now, remove the encapsulation header.  The original
	 * header has already been fixed up above.
	 */
	memmove(mtod(m, caddr_t) + ifv->ifv_encaplen, mtod(m, caddr_t),
	    ifv->ifv_encaplen);
	m_adj(m, ifv->ifv_encaplen);

	m->m_pkthdr.rcvif = &ifv->ifv_if;
	ifv->ifv_if.if_ipackets++;

#if NBPFILTER > 0
	if (ifv->ifv_if.if_bpf)
		bpf_mtap(ifv->ifv_if.if_bpf, m);
#endif

	/* Pass it back through the parent's input routine. */
	(*ifp->if_input)(&ifv->ifv_if, m);
}