freebsd-skq/sys/net/if.c

/*
 * Copyright (c) 1980, 1986, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * 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 University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University 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 REGENTS 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 REGENTS 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.
 *
 *	@(#)if.c	8.3 (Berkeley) 1/4/94
 * $Id: if.c,v 1.25 1995/12/20 21:53:38 wollman Exp $
 */

#include <sys/param.h>
#include <sys/mbuf.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/protosw.h>
#include <sys/kernel.h>
#include <sys/ioctl.h>
#include <sys/errno.h>
#include <sys/syslog.h>
#include <sys/sysctl.h>

#include <net/if.h>
#include <net/if_dl.h>
#include <net/if_types.h>
#include <net/radix.h>
#include <ether.h>

/*
 * System initialization
 */

static int ifconf __P((int, caddr_t));
static void ifinit __P((void *));
static void if_qflush __P((struct ifqueue *));
static void if_slowtimo __P((void *));
static void link_rtrequest __P((int, struct rtentry *, struct sockaddr *));

SYSINIT(interfaces, SI_SUB_PROTO_IF, SI_ORDER_FIRST, ifinit, NULL)


int	ifqmaxlen = IFQ_MAXLEN;
struct	ifnet *ifnet;

/*
 * Network interface utility routines.
 *
 * Routines with ifa_ifwith* names take sockaddr *'s as
 * parameters.
 *
 * This routine assumes that it will be called at splimp() or higher.
 */
/* ARGSUSED*/
void
ifinit(dummy)
	void *dummy;
{
	register struct ifnet *ifp;

	for (ifp = ifnet; ifp; ifp = ifp->if_next)
		if (ifp->if_snd.ifq_maxlen == 0)
			ifp->if_snd.ifq_maxlen = ifqmaxlen;
	if_slowtimo(0);
}

static int if_index = 0;
static struct ifaddr **ifnet_addrs;


/*
 * Attach an interface to the
 * list of "active" interfaces.
 */
void
if_attach(ifp)
	struct ifnet *ifp;
{
	unsigned socksize, ifasize;
	int namelen, masklen;
	char workbuf[64];
	register struct ifnet **p = &ifnet;
	register struct sockaddr_dl *sdl;
	register struct ifaddr *ifa;
	static int if_indexlim = 8;


	while (*p)
		p = &((*p)->if_next);
	*p = ifp;
	ifp->if_index = ++if_index;
	if (ifnet_addrs == 0 || if_index >= if_indexlim) {
		unsigned n = (if_indexlim <<= 1) * sizeof(ifa);
		struct ifaddr **q = (struct ifaddr **)
					malloc(n, M_IFADDR, M_WAITOK);
		bzero((caddr_t)q, n);
		if (ifnet_addrs) {
			bcopy((caddr_t)ifnet_addrs, (caddr_t)q, n/2);
			free((caddr_t)ifnet_addrs, M_IFADDR);
		}
		ifnet_addrs = q;
	}
	/*
	 * create a Link Level name for this device
	 */
	namelen = sprintf(workbuf, "%s%d", ifp->if_name, ifp->if_unit);
#define _offsetof(t, m) ((int)((caddr_t)&((t *)0)->m))
	masklen = _offsetof(struct sockaddr_dl, sdl_data[0]) + namelen;
	socksize = masklen + ifp->if_addrlen;
#define ROUNDUP(a) (1 + (((a) - 1) | (sizeof(long) - 1)))
	socksize = ROUNDUP(socksize);
	if (socksize < sizeof(*sdl))
		socksize = sizeof(*sdl);
	ifasize = sizeof(*ifa) + 2 * socksize;
	ifa = (struct ifaddr *)malloc(ifasize, M_IFADDR, M_WAITOK);
	if (ifa) {
		bzero((caddr_t)ifa, ifasize);
		sdl = (struct sockaddr_dl *)(ifa + 1);
		sdl->sdl_len = socksize;
		sdl->sdl_family = AF_LINK;
		bcopy(workbuf, sdl->sdl_data, namelen);
		sdl->sdl_nlen = namelen;
		sdl->sdl_index = ifp->if_index;
		sdl->sdl_type = ifp->if_type;
		ifnet_addrs[if_index - 1] = ifa;
		ifa->ifa_ifp = ifp;
		ifa->ifa_next = ifp->if_addrlist;
		ifa->ifa_rtrequest = link_rtrequest;
		ifp->if_addrlist = ifa;
		ifa->ifa_addr = (struct sockaddr *)sdl;

		sdl = (struct sockaddr_dl *)(socksize + (caddr_t)sdl);
		ifa->ifa_netmask = (struct sockaddr *)sdl;
		sdl->sdl_len = masklen;
		while (namelen != 0)
			sdl->sdl_data[--namelen] = 0xff;
	}
	/* XXX -- Temporary fix before changing 10 ethernet drivers */
#if NETHER > 0
	if (ifp->if_output == ether_output)
		ether_ifattach(ifp);
#endif
}
/*
 * Locate an interface based on a complete address.
 */
/*ARGSUSED*/
struct ifaddr *
ifa_ifwithaddr(addr)
	register struct sockaddr *addr;
{
	register struct ifnet *ifp;
	register struct ifaddr *ifa;

#define	equal(a1, a2) \
  (bcmp((caddr_t)(a1), (caddr_t)(a2), ((struct sockaddr *)(a1))->sa_len) == 0)
	for (ifp = ifnet; ifp; ifp = ifp->if_next)
	    for (ifa = ifp->if_addrlist; ifa; ifa = ifa->ifa_next) {
		if (ifa->ifa_addr->sa_family != addr->sa_family)
			continue;
		if (equal(addr, ifa->ifa_addr))
			return (ifa);
		if ((ifp->if_flags & IFF_BROADCAST) && ifa->ifa_broadaddr &&
		    equal(ifa->ifa_broadaddr, addr))
			return (ifa);
	}
	return ((struct ifaddr *)0);
}
/*
 * Locate the point to point interface with a given destination address.
 */
/*ARGSUSED*/
struct ifaddr *
ifa_ifwithdstaddr(addr)
	register struct sockaddr *addr;
{
	register struct ifnet *ifp;
	register struct ifaddr *ifa;

	for (ifp = ifnet; ifp; ifp = ifp->if_next)
	    if (ifp->if_flags & IFF_POINTOPOINT)
		for (ifa = ifp->if_addrlist; ifa; ifa = ifa->ifa_next) {
			if (ifa->ifa_addr->sa_family != addr->sa_family)
				continue;
			if (ifa->ifa_dstaddr && equal(addr, ifa->ifa_dstaddr))
				return (ifa);
	}
	return ((struct ifaddr *)0);
}

/*
 * Find an interface on a specific network.  If many, choice
 * is most specific found.
 */
struct ifaddr *
ifa_ifwithnet(addr)
	struct sockaddr *addr;
{
	register struct ifnet *ifp;
	register struct ifaddr *ifa;
	struct ifaddr *ifa_maybe = (struct ifaddr *) 0;
	u_int af = addr->sa_family;
	char *addr_data = addr->sa_data, *cplim;

	if (af == AF_LINK) {
	    register struct sockaddr_dl *sdl = (struct sockaddr_dl *)addr;
	    if (sdl->sdl_index && sdl->sdl_index <= if_index)
		return (ifnet_addrs[sdl->sdl_index - 1]);
	}
	for (ifp = ifnet; ifp; ifp = ifp->if_next) {
		for (ifa = ifp->if_addrlist; ifa; ifa = ifa->ifa_next) {
			register char *cp, *cp2, *cp3;

			if (ifa->ifa_addr->sa_family != af)
				next: continue;
			if (ifp->if_flags & IFF_POINTOPOINT) {
				if (equal(addr, ifa->ifa_dstaddr))
 					return (ifa);
			} else {
				if (ifa->ifa_netmask == 0)
					continue;
				cp = addr_data;
				cp2 = ifa->ifa_addr->sa_data;
				cp3 = ifa->ifa_netmask->sa_data;
				cplim = ifa->ifa_netmask->sa_len + (char *)ifa->ifa_netmask;
				while (cp3 < cplim)
					if ((*cp++ ^ *cp2++) & *cp3++)
						goto next;
				if (ifa_maybe == 0 ||
				    rn_refines((caddr_t)ifa->ifa_netmask,
				    (caddr_t)ifa_maybe->ifa_netmask))
					ifa_maybe = ifa;
			}
		}
	}
	return (ifa_maybe);
}

/*
 * Find an interface address specific to an interface best matching
 * a given address.
 */
struct ifaddr *
ifaof_ifpforaddr(addr, ifp)
	struct sockaddr *addr;
	register struct ifnet *ifp;
{
	register struct ifaddr *ifa;
	register char *cp, *cp2, *cp3;
	register char *cplim;
	struct ifaddr *ifa_maybe = 0;
	u_int af = addr->sa_family;

	if (af >= AF_MAX)
		return (0);
	for (ifa = ifp->if_addrlist; ifa; ifa = ifa->ifa_next) {
		if (ifa->ifa_addr->sa_family != af)
			continue;
		ifa_maybe = ifa;
		if (ifa->ifa_netmask == 0) {
			if (equal(addr, ifa->ifa_addr) ||
			    (ifa->ifa_dstaddr && equal(addr, ifa->ifa_dstaddr)))
				return (ifa);
			continue;
		}
		if (ifp->if_flags & IFF_POINTOPOINT) {
			if (equal(addr, ifa->ifa_dstaddr))
				return (ifa);
		} else {
			cp = addr->sa_data;
			cp2 = ifa->ifa_addr->sa_data;
			cp3 = ifa->ifa_netmask->sa_data;
			cplim = ifa->ifa_netmask->sa_len + (char *)ifa->ifa_netmask;
			for (; cp3 < cplim; cp3++)
				if ((*cp++ ^ *cp2++) & *cp3)
					break;
			if (cp3 == cplim)
				return (ifa);
		}
	}
	return (ifa_maybe);
}

#include <net/route.h>

/*
 * Default action when installing a route with a Link Level gateway.
 * Lookup an appropriate real ifa to point to.
 * This should be moved to /sys/net/link.c eventually.
 */
static void
link_rtrequest(cmd, rt, sa)
	int cmd;
	register struct rtentry *rt;
	struct sockaddr *sa;
{
	register struct ifaddr *ifa;
	struct sockaddr *dst;
	struct ifnet *ifp;

	if (cmd != RTM_ADD || ((ifa = rt->rt_ifa) == 0) ||
	    ((ifp = ifa->ifa_ifp) == 0) || ((dst = rt_key(rt)) == 0))
		return;
	ifa = ifaof_ifpforaddr(dst, ifp);
	if (ifa) {
		IFAFREE(rt->rt_ifa);
		rt->rt_ifa = ifa;
		ifa->ifa_refcnt++;
		if (ifa->ifa_rtrequest && ifa->ifa_rtrequest != link_rtrequest)
			ifa->ifa_rtrequest(cmd, rt, sa);
	}
}

/*
 * Mark an interface down and notify protocols of
 * the transition.
 * NOTE: must be called at splnet or eqivalent.
 */
void
if_down(ifp)
	register struct ifnet *ifp;
{
	register struct ifaddr *ifa;

	ifp->if_flags &= ~IFF_UP;
	for (ifa = ifp->if_addrlist; ifa; ifa = ifa->ifa_next)
		pfctlinput(PRC_IFDOWN, ifa->ifa_addr);
	if_qflush(&ifp->if_snd);
	rt_ifmsg(ifp);
}

/*
 * Mark an interface up and notify protocols of
 * the transition.
 * NOTE: must be called at splnet or eqivalent.
 */
void
if_up(ifp)
	register struct ifnet *ifp;
{

	ifp->if_flags |= IFF_UP;
#ifdef notyet
	register struct ifaddr *ifa;
	/* this has no effect on IP, and will kill all iso connections XXX */
	for (ifa = ifp->if_addrlist; ifa; ifa = ifa->ifa_next)
		pfctlinput(PRC_IFUP, ifa->ifa_addr);
#endif
	rt_ifmsg(ifp);
}

/*
 * Flush an interface queue.
 */
static void
if_qflush(ifq)
	register struct ifqueue *ifq;
{
	register struct mbuf *m, *n;

	n = ifq->ifq_head;
	while ((m = n) != 0) {
		n = m->m_act;
		m_freem(m);
	}
	ifq->ifq_head = 0;
	ifq->ifq_tail = 0;
	ifq->ifq_len = 0;
}

/*
 * Handle interface watchdog timer routines.  Called
 * from softclock, we decrement timers (if set) and
 * call the appropriate interface routine on expiration.
 */
static void
if_slowtimo(arg)
	void *arg;
{
	register struct ifnet *ifp;
	int s = splimp();

	for (ifp = ifnet; ifp; ifp = ifp->if_next) {
		if (ifp->if_timer == 0 || --ifp->if_timer)
			continue;
		if (ifp->if_watchdog)
			(*ifp->if_watchdog)(ifp);
	}
	splx(s);
	timeout(if_slowtimo, (void *)0, hz / IFNET_SLOWHZ);
}

/*
 * Map interface name to
 * interface structure pointer.
 */
struct ifnet *
ifunit(name)
	register char *name;
{
	register char *cp;
	register struct ifnet *ifp;
	int unit;
	unsigned len;
	char *ep, c;

	for (cp = name; cp < name + IFNAMSIZ && *cp; cp++)
		if (*cp >= '0' && *cp <= '9')
			break;
	if (*cp == '\0' || cp == name + IFNAMSIZ)
		return ((struct ifnet *)0);
	/*
	 * Save first char of unit, and pointer to it,
	 * so we can put a null there to avoid matching
	 * initial substrings of interface names.
	 */
	len = cp - name + 1;
	c = *cp;
	ep = cp;
	for (unit = 0; *cp >= '0' && *cp <= '9'; )
		unit = unit * 10 + *cp++ - '0';
	*ep = 0;
	for (ifp = ifnet; ifp; ifp = ifp->if_next) {
		if (bcmp(ifp->if_name, name, len))
			continue;
		if (unit == ifp->if_unit)
			break;
	}
	*ep = c;
	return (ifp);
}

/*
 * Interface ioctls.
 */
int
ifioctl(so, cmd, data, p)
	struct socket *so;
	int cmd;
	caddr_t data;
	struct proc *p;
{
	register struct ifnet *ifp;
	register struct ifreq *ifr;
	int error;

	switch (cmd) {

	case SIOCGIFCONF:
	case OSIOCGIFCONF:
		return (ifconf(cmd, data));
	}
	ifr = (struct ifreq *)data;
	ifp = ifunit(ifr->ifr_name);
	if (ifp == 0)
		return (ENXIO);
	switch (cmd) {

	case SIOCGIFFLAGS:
		ifr->ifr_flags = ifp->if_flags;
		break;

	case SIOCGIFMETRIC:
		ifr->ifr_metric = ifp->if_metric;
		break;

	case SIOCGIFMTU:
		ifr->ifr_mtu = ifp->if_mtu;
		break;

	case SIOCGIFPHYS:
		ifr->ifr_phys = ifp->if_physical;
		break;

	case SIOCSIFFLAGS:
		error = suser(p->p_ucred, &p->p_acflag);
		if (error)
			return (error);
		if (ifp->if_flags & IFF_UP && (ifr->ifr_flags & IFF_UP) == 0) {
			int s = splimp();
			if_down(ifp);
			splx(s);
		}
		if (ifr->ifr_flags & IFF_UP && (ifp->if_flags & IFF_UP) == 0) {
			int s = splimp();
			if_up(ifp);
			splx(s);
		}
		ifp->if_flags = (ifp->if_flags & IFF_CANTCHANGE) |
			(ifr->ifr_flags &~ IFF_CANTCHANGE);
		if (ifp->if_ioctl)
			(void) (*ifp->if_ioctl)(ifp, cmd, data);
		break;

	case SIOCSIFMETRIC:
		error = suser(p->p_ucred, &p->p_acflag);
		if (error)
			return (error);
		ifp->if_metric = ifr->ifr_metric;
		break;

	case SIOCSIFPHYS:
		error = suser(p->p_ucred, &p->p_acflag);
		if (error) return error;

		if (!ifp->if_ioctl) return EOPNOTSUPP;
		return ifp->if_ioctl(ifp, cmd, data);

	case SIOCSIFMTU:
		error = suser(p->p_ucred, &p->p_acflag);
		if (error)
			return (error);
		if (ifp->if_ioctl == NULL)
			return (EOPNOTSUPP);
		/*
		 * 72 was chosen below because it is the size of a TCP/IP
		 * header (40) + the minimum mss (32).
		 */
		if (ifr->ifr_mtu < 72 || ifr->ifr_mtu > 65535)
			return (EINVAL);
		return ((*ifp->if_ioctl)(ifp, cmd, data));

	case SIOCADDMULTI:
	case SIOCDELMULTI:
		error = suser(p->p_ucred, &p->p_acflag);
		if (error)
			return (error);
		if (ifp->if_ioctl == NULL)
			return (EOPNOTSUPP);
		return ((*ifp->if_ioctl)(ifp, cmd, data));

	default:
		if (so->so_proto == 0)
			return (EOPNOTSUPP);
#ifndef COMPAT_43
		return ((*so->so_proto->pr_usrreq)(so, PRU_CONTROL,
			(struct mbuf *)cmd, (struct mbuf *)data,
			(struct mbuf *)ifp));
#else
	    {
		int ocmd = cmd;

		switch (cmd) {

		case SIOCSIFDSTADDR:
		case SIOCSIFADDR:
		case SIOCSIFBRDADDR:
		case SIOCSIFNETMASK:
#if BYTE_ORDER != BIG_ENDIAN
			if (ifr->ifr_addr.sa_family == 0 &&
			    ifr->ifr_addr.sa_len < 16) {
				ifr->ifr_addr.sa_family = ifr->ifr_addr.sa_len;
				ifr->ifr_addr.sa_len = 16;
			}
#else
			if (ifr->ifr_addr.sa_len == 0)
				ifr->ifr_addr.sa_len = 16;
#endif
			break;

		case OSIOCGIFADDR:
			cmd = SIOCGIFADDR;
			break;

		case OSIOCGIFDSTADDR:
			cmd = SIOCGIFDSTADDR;
			break;

		case OSIOCGIFBRDADDR:
			cmd = SIOCGIFBRDADDR;
			break;

		case OSIOCGIFNETMASK:
			cmd = SIOCGIFNETMASK;
		}
		error =  ((*so->so_proto->pr_usrreq)(so, PRU_CONTROL,
			  /*
			   * XXX callees reverse the following bogus casts,
			   * but it would be easier to use a separate
			   * interface that is guaranteed to work.
			   */
			  (struct mbuf *)cmd, (struct mbuf *)data,
			  (struct mbuf *)ifp));
		switch (ocmd) {

		case OSIOCGIFADDR:
		case OSIOCGIFDSTADDR:
		case OSIOCGIFBRDADDR:
		case OSIOCGIFNETMASK:
			*(u_short *)&ifr->ifr_addr = ifr->ifr_addr.sa_family;
		}
		return (error);

	    }
#endif
	}
	return (0);
}

/*
 * Set/clear promiscuous mode on interface ifp based on the truth value
 * of pswitch.  The calls are reference counted so that only the first
 * "on" request actually has an effect, as does the final "off" request.
 * Results are undefined if the "off" and "on" requests are not matched.
 */
int
ifpromisc(ifp, pswitch)
	struct ifnet *ifp;
	int pswitch;
{
	struct ifreq ifr;

	if (pswitch) {
		/*
		 * If the device is not configured up, we cannot put it in
		 * promiscuous mode.
		 */
		if ((ifp->if_flags & IFF_UP) == 0)
			return (ENETDOWN);
		if (ifp->if_pcount++ != 0)
			return (0);
		ifp->if_flags |= IFF_PROMISC;
		log(LOG_INFO, "%s%d: promiscuous mode enabled\n",
		    ifp->if_name, ifp->if_unit);
	} else {
		if (--ifp->if_pcount > 0)
			return (0);
		ifp->if_flags &= ~IFF_PROMISC;
	}
	ifr.ifr_flags = ifp->if_flags;
	return ((*ifp->if_ioctl)(ifp, SIOCSIFFLAGS, (caddr_t)&ifr));
}

/*
 * Return interface configuration
 * of system.  List may be used
 * in later ioctl's (above) to get
 * other information.
 */
/*ARGSUSED*/
static int
ifconf(cmd, data)
	int cmd;
	caddr_t data;
{
	register struct ifconf *ifc = (struct ifconf *)data;
	register struct ifnet *ifp = ifnet;
	register struct ifaddr *ifa;
	struct ifreq ifr, *ifrp;
	int space = ifc->ifc_len, error = 0;

	ifrp = ifc->ifc_req;
	for (; space > sizeof (ifr) && ifp; ifp = ifp->if_next) {
		char workbuf[64];
		int ifnlen;

		ifnlen = sprintf(workbuf, "%s%d", ifp->if_name, ifp->if_unit);
		if(ifnlen + 1 > sizeof ifr.ifr_name) {
			error = ENAMETOOLONG;
		} else {
			strcpy(ifr.ifr_name, workbuf);
		}

		if ((ifa = ifp->if_addrlist) == 0) {
			bzero((caddr_t)&ifr.ifr_addr, sizeof(ifr.ifr_addr));
			error = copyout((caddr_t)&ifr, (caddr_t)ifrp,
			    sizeof (ifr));
			if (error)
				break;
			space -= sizeof (ifr), ifrp++;
		} else
		    for ( ; space > sizeof (ifr) && ifa; ifa = ifa->ifa_next) {
			register struct sockaddr *sa = ifa->ifa_addr;
#ifdef COMPAT_43
			if (cmd == OSIOCGIFCONF) {
				struct osockaddr *osa =
					 (struct osockaddr *)&ifr.ifr_addr;
				ifr.ifr_addr = *sa;
				osa->sa_family = sa->sa_family;
				error = copyout((caddr_t)&ifr, (caddr_t)ifrp,
						sizeof (ifr));
				ifrp++;
			} else
#endif
			if (sa->sa_len <= sizeof(*sa)) {
				ifr.ifr_addr = *sa;
				error = copyout((caddr_t)&ifr, (caddr_t)ifrp,
						sizeof (ifr));
				ifrp++;
			} else {
				space -= sa->sa_len - sizeof(*sa);
				if (space < sizeof (ifr))
					break;
				error = copyout((caddr_t)&ifr, (caddr_t)ifrp,
						sizeof (ifr.ifr_name));
				if (error == 0)
				    error = copyout((caddr_t)sa,
				      (caddr_t)&ifrp->ifr_addr, sa->sa_len);
				ifrp = (struct ifreq *)
					(sa->sa_len + (caddr_t)&ifrp->ifr_addr);
			}
			if (error)
				break;
			space -= sizeof (ifr);
		}
	}
	ifc->ifc_len -= space;
	return (error);
}

SYSCTL_NODE(_net, PF_LINK, link, CTLFLAG_RW, 0, "Link layers");