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File: [cvs.NetBSD.org] / src / sys / netinet / ip_input.c (download)

Revision 1.347, Mon Dec 12 03:55:57 2016 UTC (10 months, 1 week ago) by ozaki-r
Branch: MAIN
CVS Tags: pgoyette-localcount-20170107, bouyer-socketcan-base
Branch point for: bouyer-socketcan
Changes since 1.346: +2 -3 lines

Make the routing table and rtcaches MP-safe

See the following descriptions for details.

Proposed on tech-kern and tech-net


Overview
--------

We protect the routing table with a rwock and protect
rtcaches with another rwlock. Each rtentry is protected
from being freed or updated via reference counting and psref.

Global rwlocks
--------------

There are two rwlocks; one for the routing table (rt_lock) and
the other for rtcaches (rtcache_lock). rtcache_lock covers
all existing rtcaches; there may have room for optimizations
(future work).

The locking order is rtcache_lock first and rt_lock is next.

rtentry references
------------------

References to an rtentry is managed with reference counting
and psref. Either of the two mechanisms is used depending on
where a rtentry is obtained. Reference counting is used when
we obtain a rtentry from the routing table directly via
rtalloc1 and rtrequest{,1} while psref is used when we obtain
a rtentry from a rtcache via rtcache_* APIs. In both cases,
a caller can sleep/block with holding an obtained rtentry.

The reasons why we use two different mechanisms are (i) only
using reference counting hurts the performance due to atomic
instructions (rtcache case) (ii) ease of implementation;
applying psref to APIs such rtaloc1 and rtrequest{,1} requires
additional works (adding a local variable and an argument).

We will finally migrate to use only psref but we can do it
when we have a lockless routing table alternative.

Reference counting for rtentry
------------------------------

rt_refcnt now doesn't count permanent references such as for
rt_timers and rtcaches, instead it is used only for temporal
references when obtaining a rtentry via rtalloc1 and rtrequest{,1}.
We can do so because destroying a rtentry always involves
removing references of rt_timers and rtcaches to the rtentry
and we don't need to track such references. This also makes
it easy to wait for readers to release references on deleting
or updating a rtentry, i.e., we can simply wait until the
reference counter is 0 or 1. (If there are permanent references
the counter can be arbitrary.)

rt_ref increments a reference counter of a rtentry and rt_unref
decrements it. rt_ref is called inside APIs (rtalloc1 and
rtrequest{,1} so users don't need to care about it while
users must call rt_unref to an obtained rtentry after using it.

rtfree is removed and we use rt_unref and rt_free instead.
rt_unref now just decrements the counter of a given rtentry
and rt_free just tries to destroy a given rtentry.

See the next section for destructions of rtentries by rt_free.

Destructions of rtentries
-------------------------

We destroy a rtentry only when we call rtrequst{,1}(RTM_DELETE);
the original implementation can destroy in any rtfree where it's
the last reference. If we use reference counting or psref, it's
easy to understand if the place that a rtentry is destroyed is
fixed.

rt_free waits for references to a given rtentry to be released
before actually destroying the rtentry. rt_free uses a condition
variable (cv_wait) (and psref_target_destroy for psref) to wait.

Unfortunately rtrequst{,1}(RTM_DELETE) can be called in softint
that we cannot use cv_wait. In that case, we have to defer the
destruction to a workqueue.

rtentry#rt_cv, rtentry#rt_psref and global variables
(see rt_free_global) are added to conduct the procedure.

Updates of rtentries
--------------------

One difficulty to use refcnt/psref instead of rwlock for rtentry
is updates of rtentries. We need an additional mechanism to
prevent readers from seeing inconsistency of a rtentry being
updated.

We introduce RTF_UPDATING flag to rtentries that are updating.
While the flag is set to a rtentry, users cannot acquire the
rtentry. By doing so, we avoid users to see inconsistent
rtentries.

There are two options when a user tries to acquire a rtentry
with the RTF_UPDATING flag; if a user runs in softint context
the user fails to acquire a rtentry (NULL is returned).
Otherwise a user waits until the update completes by waiting
on cv.

The procedure of a updater is simpler to destruction of
a rtentry. Wait on cv (and psref) and after all readers left,
proceed with the update.

Global variables (see rt_update_global) are added to conduct
the procedure.

Currently we apply the mechanism to only RTM_CHANGE in
rtsock.c. We would have to apply other codes. See
"Known issues" section.

psref for rtentry
-----------------

When we obtain a rtentry from a rtcache via rtcache_* APIs,
psref is used to reference to the rtentry.

rtcache_ref acquires a reference to a rtentry with psref
and rtcache_unref releases the reference after using it.
rtcache_ref is called inside rtcache_* APIs and users don't
need to take care of it while users must call rtcache_unref
to release the reference.

struct psref and int bound that is needed for psref is
embedded into struct route. By doing so we don't need to
add local variables and additional argument to APIs.

However this adds another constraint to psref other than
reference counting one's; holding a reference of an rtentry
via a rtcache is allowed by just one caller at the same time.
So we must not acquire a rtentry via a rtcache twice and
avoid a recursive use of a rtcache. And also a rtcache must
be arranged to be used by a LWP/softint at the same time
somehow. For IP forwarding case, we have per-CPU rtcaches
used in softint so the constraint is guaranteed. For a h
rtcache of a PCB case, the constraint is guaranteed by the
solock of each PCB. Any other cases (pf, ipf, stf and ipsec)
are currently guaranteed by only the existence of the global
locks (softnet_lock and/or KERNEL_LOCK). If we've found the
cases that we cannot guarantee the constraint, we would need
to introduce other rtcache APIs that use simple reference
counting.

psref of rtcache is created with IPL_SOFTNET and so rtcache
shouldn't used at an IPL higher than IPL_SOFTNET.

Note that rtcache_free is used to invalidate a given rtcache.
We don't need another care by my change; just keep them as
they are.

Performance impact
------------------

When NET_MPSAFE is disabled the performance drop is 3% while
when it's enabled the drop is increased to 11%. The difference
comes from that currently we don't take any global locks and
don't use psref if NET_MPSAFE is disabled.

We can optimize the performance of the case of NET_MPSAFE
on by reducing lookups of rtcache that uses psref;
currently we do two lookups but we should be able to trim
one of two. This is a future work.

Known issues
------------

There are two known issues to be solved; one is that
a caller of rtrequest(RTM_ADD) may change rtentry (see rtinit).
We need to prevent new references during the update. Or
we may be able to remove the code (perhaps, need more
investigations).

The other is rtredirect that updates a rtentry. We need
to apply our update mechanism, however it's not easy because
rtredirect is called in softint and we cannot apply our
mechanism simply. One solution is to defer rtredirect to
a workqueue but it requires some code restructuring.

/*	$NetBSD: ip_input.c,v 1.347 2016/12/12 03:55:57 ozaki-r Exp $	*/

/*
 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
 * 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. Neither the name of the project 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 PROJECT 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 PROJECT 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 (c) 1998 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Public Access Networks Corporation ("Panix").  It was developed under
 * contract to Panix by Eric Haszlakiewicz and Thor Lancelot Simon.
 *
 * 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.
 *
 * 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 (c) 1982, 1986, 1988, 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. 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.
 *
 *	@(#)ip_input.c	8.2 (Berkeley) 1/4/94
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: ip_input.c,v 1.347 2016/12/12 03:55:57 ozaki-r Exp $");

#ifdef _KERNEL_OPT
#include "opt_inet.h"
#include "opt_compat_netbsd.h"
#include "opt_gateway.h"
#include "opt_ipsec.h"
#include "opt_mrouting.h"
#include "opt_mbuftrace.h"
#include "opt_inet_csum.h"
#include "opt_net_mpsafe.h"
#endif

#include "arp.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/cpu.h>
#include <sys/mbuf.h>
#include <sys/domain.h>
#include <sys/protosw.h>
#include <sys/socket.h>
#include <sys/socketvar.h>
#include <sys/errno.h>
#include <sys/time.h>
#include <sys/kernel.h>
#include <sys/pool.h>
#include <sys/sysctl.h>
#include <sys/kauth.h>

#include <net/if.h>
#include <net/if_dl.h>
#include <net/route.h>
#include <net/pktqueue.h>
#include <net/pfil.h>

#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#include <netinet/in_pcb.h>
#include <netinet/in_proto.h>
#include <netinet/in_var.h>
#include <netinet/ip_var.h>
#include <netinet/ip_private.h>
#include <netinet/ip_icmp.h>
/* just for gif_ttl */
#include <netinet/in_gif.h>
#include "gif.h"
#include <net/if_gre.h>
#include "gre.h"

#ifdef MROUTING
#include <netinet/ip_mroute.h>
#endif
#include <netinet/portalgo.h>

#ifdef IPSEC
#include <netipsec/ipsec.h>
#endif

#ifndef	IPFORWARDING
#ifdef GATEWAY
#define	IPFORWARDING	1	/* forward IP packets not for us */
#else /* GATEWAY */
#define	IPFORWARDING	0	/* don't forward IP packets not for us */
#endif /* GATEWAY */
#endif /* IPFORWARDING */
#ifndef	IPSENDREDIRECTS
#define	IPSENDREDIRECTS	1
#endif
#ifndef IPFORWSRCRT
#define	IPFORWSRCRT	1	/* forward source-routed packets */
#endif
#ifndef IPALLOWSRCRT
#define	IPALLOWSRCRT	1	/* allow source-routed packets */
#endif
#ifndef IPMTUDISC
#define IPMTUDISC	1
#endif
#ifndef IPMTUDISCTIMEOUT
#define IPMTUDISCTIMEOUT (10 * 60)	/* as per RFC 1191 */
#endif

#ifdef COMPAT_50
#include <compat/sys/time.h>
#include <compat/sys/socket.h>
#endif

/*
 * Note: DIRECTED_BROADCAST is handled this way so that previous
 * configuration using this option will Just Work.
 */
#ifndef IPDIRECTEDBCAST
#ifdef DIRECTED_BROADCAST
#define IPDIRECTEDBCAST	1
#else
#define	IPDIRECTEDBCAST	0
#endif /* DIRECTED_BROADCAST */
#endif /* IPDIRECTEDBCAST */
int	ipforwarding = IPFORWARDING;
int	ipsendredirects = IPSENDREDIRECTS;
int	ip_defttl = IPDEFTTL;
int	ip_forwsrcrt = IPFORWSRCRT;
int	ip_directedbcast = IPDIRECTEDBCAST;
int	ip_allowsrcrt = IPALLOWSRCRT;
int	ip_mtudisc = IPMTUDISC;
int	ip_mtudisc_timeout = IPMTUDISCTIMEOUT;
#ifdef DIAGNOSTIC
int	ipprintfs = 0;
#endif

int	ip_do_randomid = 0;

/*
 * XXX - Setting ip_checkinterface mostly implements the receive side of
 * the Strong ES model described in RFC 1122, but since the routing table
 * and transmit implementation do not implement the Strong ES model,
 * setting this to 1 results in an odd hybrid.
 *
 * XXX - ip_checkinterface currently must be disabled if you use ipnat
 * to translate the destination address to another local interface.
 *
 * XXX - ip_checkinterface must be disabled if you add IP aliases
 * to the loopback interface instead of the interface where the
 * packets for those addresses are received.
 */
static int		ip_checkinterface	__read_mostly = 0;

struct rttimer_queue *ip_mtudisc_timeout_q = NULL;

pktqueue_t *		ip_pktq			__read_mostly;
pfil_head_t *		inet_pfil_hook		__read_mostly;
ipid_state_t *		ip_ids			__read_mostly;
percpu_t *		ipstat_percpu		__read_mostly;

static percpu_t		*ipforward_rt_percpu	__cacheline_aligned;

uint16_t ip_id;

#ifdef INET_CSUM_COUNTERS
#include <sys/device.h>

struct evcnt ip_hwcsum_bad = EVCNT_INITIALIZER(EVCNT_TYPE_MISC,
    NULL, "inet", "hwcsum bad");
struct evcnt ip_hwcsum_ok = EVCNT_INITIALIZER(EVCNT_TYPE_MISC,
    NULL, "inet", "hwcsum ok");
struct evcnt ip_swcsum = EVCNT_INITIALIZER(EVCNT_TYPE_MISC,
    NULL, "inet", "swcsum");

#define	INET_CSUM_COUNTER_INCR(ev)	(ev)->ev_count++

EVCNT_ATTACH_STATIC(ip_hwcsum_bad);
EVCNT_ATTACH_STATIC(ip_hwcsum_ok);
EVCNT_ATTACH_STATIC(ip_swcsum);

#else

#define	INET_CSUM_COUNTER_INCR(ev)	/* nothing */

#endif /* INET_CSUM_COUNTERS */

/*
 * We need to save the IP options in case a protocol wants to respond
 * to an incoming packet over the same route if the packet got here
 * using IP source routing.  This allows connection establishment and
 * maintenance when the remote end is on a network that is not known
 * to us.
 */

static int	ip_nhops = 0;

static	struct ip_srcrt {
	struct	in_addr dst;			/* final destination */
	char	nop;				/* one NOP to align */
	char	srcopt[IPOPT_OFFSET + 1];	/* OPTVAL, OLEN and OFFSET */
	struct	in_addr route[MAX_IPOPTLEN/sizeof(struct in_addr)];
} ip_srcrt;

static int ip_drainwanted;

struct	sockaddr_in ipaddr = {
	.sin_len = sizeof(ipaddr),
	.sin_family = AF_INET,
};

static void save_rte(u_char *, struct in_addr);

#ifdef MBUFTRACE
struct mowner ip_rx_mowner = MOWNER_INIT("internet", "rx");
struct mowner ip_tx_mowner = MOWNER_INIT("internet", "tx");
#endif

static void		ipintr(void *);
static void		ip_input(struct mbuf *);
static void		ip_forward(struct mbuf *, int, struct ifnet *);
static bool		ip_dooptions(struct mbuf *);
static struct in_ifaddr *ip_rtaddr(struct in_addr, struct psref *);
static void		sysctl_net_inet_ip_setup(struct sysctllog **);

static struct in_ifaddr	*ip_match_our_address(struct ifnet *, struct ip *,
			    int *);
static struct in_ifaddr	*ip_match_our_address_broadcast(struct ifnet *,
			    struct ip *);

#ifdef NET_MPSAFE
#define	SOFTNET_LOCK()		mutex_enter(softnet_lock)
#define	SOFTNET_UNLOCK()	mutex_exit(softnet_lock)
#else
#define	SOFTNET_LOCK()		KASSERT(mutex_owned(softnet_lock))
#define	SOFTNET_UNLOCK()	KASSERT(mutex_owned(softnet_lock))
#endif

/*
 * IP initialization: fill in IP protocol switch table.
 * All protocols not implemented in kernel go to raw IP protocol handler.
 */
void
ip_init(void)
{
	const struct protosw *pr;

	in_init();
	sysctl_net_inet_ip_setup(NULL);

	pr = pffindproto(PF_INET, IPPROTO_RAW, SOCK_RAW);
	KASSERT(pr != NULL);

	ip_pktq = pktq_create(IFQ_MAXLEN, ipintr, NULL);
	KASSERT(ip_pktq != NULL);

	for (u_int i = 0; i < IPPROTO_MAX; i++) {
		ip_protox[i] = pr - inetsw;
	}
	for (pr = inetdomain.dom_protosw;
	    pr < inetdomain.dom_protoswNPROTOSW; pr++)
		if (pr->pr_domain->dom_family == PF_INET &&
		    pr->pr_protocol && pr->pr_protocol != IPPROTO_RAW)
			ip_protox[pr->pr_protocol] = pr - inetsw;

	ip_reass_init();

	ip_ids = ip_id_init();
	ip_id = time_uptime & 0xfffff;

#ifdef GATEWAY
	ipflow_init();
#endif

	/* Register our Packet Filter hook. */
	inet_pfil_hook = pfil_head_create(PFIL_TYPE_AF, (void *)AF_INET);
	KASSERT(inet_pfil_hook != NULL);

#ifdef MBUFTRACE
	MOWNER_ATTACH(&ip_tx_mowner);
	MOWNER_ATTACH(&ip_rx_mowner);
#endif /* MBUFTRACE */

	ipstat_percpu = percpu_alloc(sizeof(uint64_t) * IP_NSTATS);

	ipforward_rt_percpu = percpu_alloc(sizeof(struct route));
	if (ipforward_rt_percpu == NULL)
		panic("failed to allocate ipforward_rt_percpu");
}

static struct in_ifaddr *
ip_match_our_address(struct ifnet *ifp, struct ip *ip, int *downmatch)
{
	struct in_ifaddr *ia = NULL;
	int checkif;

	/*
	 * Enable a consistency check between the destination address
	 * and the arrival interface for a unicast packet (the RFC 1122
	 * strong ES model) if IP forwarding is disabled and the packet
	 * is not locally generated.
	 *
	 * XXX - Checking also should be disabled if the destination
	 * address is ipnat'ed to a different interface.
	 *
	 * XXX - Checking is incompatible with IP aliases added
	 * to the loopback interface instead of the interface where
	 * the packets are received.
	 *
	 * XXX - We need to add a per ifaddr flag for this so that
	 * we get finer grain control.
	 */
	checkif = ip_checkinterface && (ipforwarding == 0) &&
	    (ifp->if_flags & IFF_LOOPBACK) == 0;

	IN_ADDRHASH_READER_FOREACH(ia, ip->ip_dst.s_addr) {
		if (in_hosteq(ia->ia_addr.sin_addr, ip->ip_dst)) {
			if (ia->ia4_flags & IN_IFF_NOTREADY)
				continue;
			if (checkif && ia->ia_ifp != ifp)
				continue;
			if ((ia->ia_ifp->if_flags & IFF_UP) != 0 &&
			    (ia->ia4_flags & IN_IFF_DETACHED) == 0)
				break;
			else
				(*downmatch)++;
		}
	}

	return ia;
}

static struct in_ifaddr *
ip_match_our_address_broadcast(struct ifnet *ifp, struct ip *ip)
{
	struct in_ifaddr *ia = NULL;
	struct ifaddr *ifa;

	IFADDR_READER_FOREACH(ifa, ifp) {
		if (ifa->ifa_addr->sa_family != AF_INET)
			continue;
		ia = ifatoia(ifa);
		if (ia->ia4_flags & (IN_IFF_NOTREADY | IN_IFF_DETACHED))
			continue;
		if (in_hosteq(ip->ip_dst, ia->ia_broadaddr.sin_addr) ||
		    in_hosteq(ip->ip_dst, ia->ia_netbroadcast) ||
		    /*
		     * Look for all-0's host part (old broadcast addr),
		     * either for subnet or net.
		     */
		    ip->ip_dst.s_addr == ia->ia_subnet ||
		    ip->ip_dst.s_addr == ia->ia_net)
			goto matched;
		/*
		 * An interface with IP address zero accepts
		 * all packets that arrive on that interface.
		 */
		if (in_nullhost(ia->ia_addr.sin_addr))
			goto matched;
	}
	ia = NULL;

matched:
	return ia;
}

/*
 * IP software interrupt routine.
 */
static void
ipintr(void *arg __unused)
{
	struct mbuf *m;

	KASSERT(cpu_softintr_p());

#ifndef NET_MPSAFE
	mutex_enter(softnet_lock);
#endif
	while ((m = pktq_dequeue(ip_pktq)) != NULL) {
		ip_input(m);
	}
#ifndef NET_MPSAFE
	mutex_exit(softnet_lock);
#endif
}

/*
 * IP input routine.  Checksum and byte swap header.  If fragmented
 * try to reassemble.  Process options.  Pass to next level.
 */
static void
ip_input(struct mbuf *m)
{
	struct ip *ip = NULL;
	struct in_ifaddr *ia = NULL;
	int hlen = 0, len;
	int downmatch;
	int srcrt = 0;
	ifnet_t *ifp;
	struct psref psref;
	int s;

	KASSERTMSG(cpu_softintr_p(), "ip_input: not in the software "
	    "interrupt handler; synchronization assumptions violated");

	MCLAIM(m, &ip_rx_mowner);
	KASSERT((m->m_flags & M_PKTHDR) != 0);

	ifp = m_get_rcvif_psref(m, &psref);
	if (__predict_false(ifp == NULL))
		goto out;

	/*
	 * If no IP addresses have been set yet but the interfaces
	 * are receiving, can't do anything with incoming packets yet.
	 * Note: we pre-check without locks held.
	 */
	if (IN_ADDRLIST_READER_EMPTY())
		goto out;
	IP_STATINC(IP_STAT_TOTAL);

	/*
	 * If the IP header is not aligned, slurp it up into a new
	 * mbuf with space for link headers, in the event we forward
	 * it.  Otherwise, if it is aligned, make sure the entire
	 * base IP header is in the first mbuf of the chain.
	 */
	if (IP_HDR_ALIGNED_P(mtod(m, void *)) == 0) {
		if ((m = m_copyup(m, sizeof(struct ip),
				  (max_linkhdr + 3) & ~3)) == NULL) {
			/* XXXJRT new stat, please */
			IP_STATINC(IP_STAT_TOOSMALL);
			goto out;
		}
	} else if (__predict_false(m->m_len < sizeof (struct ip))) {
		if ((m = m_pullup(m, sizeof (struct ip))) == NULL) {
			IP_STATINC(IP_STAT_TOOSMALL);
			goto out;
		}
	}
	ip = mtod(m, struct ip *);
	if (ip->ip_v != IPVERSION) {
		IP_STATINC(IP_STAT_BADVERS);
		goto out;
	}
	hlen = ip->ip_hl << 2;
	if (hlen < sizeof(struct ip)) {	/* minimum header length */
		IP_STATINC(IP_STAT_BADHLEN);
		goto out;
	}
	if (hlen > m->m_len) {
		if ((m = m_pullup(m, hlen)) == NULL) {
			IP_STATINC(IP_STAT_BADHLEN);
			goto out;
		}
		ip = mtod(m, struct ip *);
	}

	/*
	 * RFC1122: packets with a multicast source address are
	 * not allowed.
	 */
	if (IN_MULTICAST(ip->ip_src.s_addr)) {
		IP_STATINC(IP_STAT_BADADDR);
		goto out;
	}

	/* 127/8 must not appear on wire - RFC1122 */
	if ((ntohl(ip->ip_dst.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET ||
	    (ntohl(ip->ip_src.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET) {
		if ((ifp->if_flags & IFF_LOOPBACK) == 0) {
			IP_STATINC(IP_STAT_BADADDR);
			goto out;
		}
	}

	switch (m->m_pkthdr.csum_flags &
		((ifp->if_csum_flags_rx & M_CSUM_IPv4) |
		 M_CSUM_IPv4_BAD)) {
	case M_CSUM_IPv4|M_CSUM_IPv4_BAD:
		INET_CSUM_COUNTER_INCR(&ip_hwcsum_bad);
		IP_STATINC(IP_STAT_BADSUM);
		goto out;

	case M_CSUM_IPv4:
		/* Checksum was okay. */
		INET_CSUM_COUNTER_INCR(&ip_hwcsum_ok);
		break;

	default:
		/*
		 * Must compute it ourselves.  Maybe skip checksum on
		 * loopback interfaces.
		 */
		if (__predict_true(!(ifp->if_flags & IFF_LOOPBACK) ||
		    ip_do_loopback_cksum)) {
			INET_CSUM_COUNTER_INCR(&ip_swcsum);
			if (in_cksum(m, hlen) != 0) {
				IP_STATINC(IP_STAT_BADSUM);
				goto out;
			}
		}
		break;
	}

	/* Retrieve the packet length. */
	len = ntohs(ip->ip_len);

	/*
	 * Check for additional length bogosity
	 */
	if (len < hlen) {
		IP_STATINC(IP_STAT_BADLEN);
		goto out;
	}

	/*
	 * Check that the amount of data in the buffers
	 * is as at least much as the IP header would have us expect.
	 * Trim mbufs if longer than we expect.
	 * Drop packet if shorter than we expect.
	 */
	if (m->m_pkthdr.len < len) {
		IP_STATINC(IP_STAT_TOOSHORT);
		goto out;
	}
	if (m->m_pkthdr.len > len) {
		if (m->m_len == m->m_pkthdr.len) {
			m->m_len = len;
			m->m_pkthdr.len = len;
		} else
			m_adj(m, len - m->m_pkthdr.len);
	}

	/*
	 * Assume that we can create a fast-forward IP flow entry
	 * based on this packet.
	 */
	m->m_flags |= M_CANFASTFWD;

	/*
	 * Run through list of hooks for input packets.  If there are any
	 * filters which require that additional packets in the flow are
	 * not fast-forwarded, they must clear the M_CANFASTFWD flag.
	 * Note that filters must _never_ set this flag, as another filter
	 * in the list may have previously cleared it.
	 */
#if defined(IPSEC)
	if (!ipsec_used || !ipsec_indone(m))
#else
	if (1)
#endif
	{
		struct in_addr odst = ip->ip_dst;
		bool freed;

		freed = pfil_run_hooks(inet_pfil_hook, &m, ifp, PFIL_IN) != 0;
		if (freed || m == NULL) {
			m = NULL;
			goto out;
		}
		ip = mtod(m, struct ip *);
		hlen = ip->ip_hl << 2;

		/*
		 * XXX The setting of "srcrt" here is to prevent ip_forward()
		 * from generating ICMP redirects for packets that have
		 * been redirected by a hook back out on to the same LAN that
		 * they came from and is not an indication that the packet
		 * is being inffluenced by source routing options.  This
		 * allows things like
		 * "rdr tlp0 0/0 port 80 -> 1.1.1.200 3128 tcp"
		 * where tlp0 is both on the 1.1.1.0/24 network and is the
		 * default route for hosts on 1.1.1.0/24.  Of course this
		 * also requires a "map tlp0 ..." to complete the story.
		 * One might argue whether or not this kind of network config.
		 * should be supported in this manner...
		 */
		srcrt = (odst.s_addr != ip->ip_dst.s_addr);
	}

#ifdef ALTQ
	/* XXX Temporary until ALTQ is changed to use a pfil hook */
	if (altq_input) {
		SOFTNET_LOCK();
		if ((*altq_input)(m, AF_INET) == 0) {
			/* Packet dropped by traffic conditioner. */
			SOFTNET_UNLOCK();
			m = NULL;
			goto out;
		}
		SOFTNET_UNLOCK();
	}
#endif

	/*
	 * Process options and, if not destined for us,
	 * ship it on.  ip_dooptions returns 1 when an
	 * error was detected (causing an icmp message
	 * to be sent and the original packet to be freed).
	 */
	ip_nhops = 0;		/* for source routed packets */
	if (hlen > sizeof (struct ip) && ip_dooptions(m)) {
		m = NULL;
		goto out;
	}

	/*
	 * Check our list of addresses, to see if the packet is for us.
	 *
	 * Traditional 4.4BSD did not consult IFF_UP at all.
	 * The behavior here is to treat addresses on !IFF_UP interface
	 * or IN_IFF_NOTREADY addresses as not mine.
	 */
	downmatch = 0;
	s = pserialize_read_enter();
	ia = ip_match_our_address(ifp, ip, &downmatch);
	if (ia != NULL) {
		pserialize_read_exit(s);
		goto ours;
	}

	if (ifp->if_flags & IFF_BROADCAST) {
		ia = ip_match_our_address_broadcast(ifp, ip);
		if (ia != NULL) {
			pserialize_read_exit(s);
			goto ours;
		}
	}
	pserialize_read_exit(s);

	if (IN_MULTICAST(ip->ip_dst.s_addr)) {
#ifdef MROUTING
		extern struct socket *ip_mrouter;

		if (ip_mrouter) {
			/*
			 * If we are acting as a multicast router, all
			 * incoming multicast packets are passed to the
			 * kernel-level multicast forwarding function.
			 * The packet is returned (relatively) intact; if
			 * ip_mforward() returns a non-zero value, the packet
			 * must be discarded, else it may be accepted below.
			 *
			 * (The IP ident field is put in the same byte order
			 * as expected when ip_mforward() is called from
			 * ip_output().)
			 */
			SOFTNET_LOCK();
			if (ip_mforward(m, ifp) != 0) {
				SOFTNET_UNLOCK();
				IP_STATINC(IP_STAT_CANTFORWARD);
				goto out;
			}
			SOFTNET_UNLOCK();

			/*
			 * The process-level routing demon needs to receive
			 * all multicast IGMP packets, whether or not this
			 * host belongs to their destination groups.
			 */
			if (ip->ip_p == IPPROTO_IGMP) {
				goto ours;
			}
			IP_STATINC(IP_STAT_CANTFORWARD);
		}
#endif
		/*
		 * See if we belong to the destination multicast group on the
		 * arrival interface.
		 */
		if (!in_multi_group(ip->ip_dst, ifp, 0)) {
			IP_STATINC(IP_STAT_CANTFORWARD);
			goto out;
		}
		goto ours;
	}
	if (ip->ip_dst.s_addr == INADDR_BROADCAST ||
	    in_nullhost(ip->ip_dst))
		goto ours;

	/*
	 * Not for us; forward if possible and desirable.
	 */
	if (ipforwarding == 0) {
		m_put_rcvif_psref(ifp, &psref);
		IP_STATINC(IP_STAT_CANTFORWARD);
		m_freem(m);
	} else {
		/*
		 * If ip_dst matched any of my address on !IFF_UP interface,
		 * and there's no IFF_UP interface that matches ip_dst,
		 * send icmp unreach.  Forwarding it will result in in-kernel
		 * forwarding loop till TTL goes to 0.
		 */
		if (downmatch) {
			m_put_rcvif_psref(ifp, &psref);
			icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, 0, 0);
			IP_STATINC(IP_STAT_CANTFORWARD);
			return;
		}
#ifdef IPSEC
		/* Perform IPsec, if any. */
		if (ipsec_used) {
			SOFTNET_LOCK();
			if (ipsec4_input(m, IP_FORWARDING |
			    (ip_directedbcast ? IP_ALLOWBROADCAST : 0)) != 0) {
				SOFTNET_UNLOCK();
				goto out;
			}
			SOFTNET_UNLOCK();
		}
#endif
		ip_forward(m, srcrt, ifp);
		m_put_rcvif_psref(ifp, &psref);
	}
	return;

ours:
	m_put_rcvif_psref(ifp, &psref);
	ifp = NULL;

	/*
	 * If offset or IP_MF are set, must reassemble.
	 */
	if (ip->ip_off & ~htons(IP_DF|IP_RF)) {
		/*
		 * Pass to IP reassembly mechanism.
		 */
		if (ip_reass_packet(&m, ip) != 0) {
			/* Failed; invalid fragment(s) or packet. */
			goto out;
		}
		if (m == NULL) {
			/* More fragments should come; silently return. */
			goto out;
		}
		/*
		 * Reassembly is done, we have the final packet.
		 * Updated cached data in local variable(s).
		 */
		ip = mtod(m, struct ip *);
		hlen = ip->ip_hl << 2;
	}

#ifdef IPSEC
	/*
	 * Enforce IPsec policy checking if we are seeing last header.
	 * Note that we do not visit this with protocols with PCB layer
	 * code - like UDP/TCP/raw IP.
	 */
	if (ipsec_used &&
	    (inetsw[ip_protox[ip->ip_p]].pr_flags & PR_LASTHDR) != 0) {
		SOFTNET_LOCK();
		if (ipsec4_input(m, 0) != 0) {
			SOFTNET_UNLOCK();
			goto out;
		}
		SOFTNET_UNLOCK();
	}
#endif

	/*
	 * Switch out to protocol's input routine.
	 */
#if IFA_STATS
	if (ia && ip) {
		struct in_ifaddr *_ia;
		/*
		 * Keep a reference from ip_match_our_address with psref
		 * is expensive, so explore ia here again.
		 */
		s = pserialize_read_enter();
		_ia = in_get_ia(ip->ip_dst);
		_ia->ia_ifa.ifa_data.ifad_inbytes += ntohs(ip->ip_len);
		pserialize_read_exit(s);
	}
#endif
	IP_STATINC(IP_STAT_DELIVERED);

	const int off = hlen, nh = ip->ip_p;

	SOFTNET_LOCK();
	(*inetsw[ip_protox[nh]].pr_input)(m, off, nh);
	SOFTNET_UNLOCK();
	return;

out:
	m_put_rcvif_psref(ifp, &psref);
	if (m != NULL)
		m_freem(m);
}

/*
 * IP timer processing.
 */
void
ip_slowtimo(void)
{

	mutex_enter(softnet_lock);
	KERNEL_LOCK(1, NULL);

	ip_reass_slowtimo();

	KERNEL_UNLOCK_ONE(NULL);
	mutex_exit(softnet_lock);
}

/*
 * IP drain processing.
 */
void
ip_drain(void)
{

	KERNEL_LOCK(1, NULL);
	ip_reass_drain();
	KERNEL_UNLOCK_ONE(NULL);
}

/*
 * ip_dooptions: perform option processing on a datagram, possibly discarding
 * it if bad options are encountered, or forwarding it if source-routed.
 *
 * => Returns true if packet has been forwarded/freed.
 * => Returns false if the packet should be processed further.
 */
static bool
ip_dooptions(struct mbuf *m)
{
	struct ip *ip = mtod(m, struct ip *);
	u_char *cp, *cp0;
	struct ip_timestamp *ipt;
	struct in_ifaddr *ia;
	int opt, optlen, cnt, off, code, type = ICMP_PARAMPROB, forward = 0;
	struct in_addr dst;
	n_time ntime;
	struct ifaddr *ifa;
	int s;

	dst = ip->ip_dst;
	cp = (u_char *)(ip + 1);
	cnt = (ip->ip_hl << 2) - sizeof (struct ip);
	for (; cnt > 0; cnt -= optlen, cp += optlen) {
		opt = cp[IPOPT_OPTVAL];
		if (opt == IPOPT_EOL)
			break;
		if (opt == IPOPT_NOP)
			optlen = 1;
		else {
			if (cnt < IPOPT_OLEN + sizeof(*cp)) {
				code = &cp[IPOPT_OLEN] - (u_char *)ip;
				goto bad;
			}
			optlen = cp[IPOPT_OLEN];
			if (optlen < IPOPT_OLEN + sizeof(*cp) || optlen > cnt) {
				code = &cp[IPOPT_OLEN] - (u_char *)ip;
				goto bad;
			}
		}
		switch (opt) {

		default:
			break;

		/*
		 * Source routing with record.
		 * Find interface with current destination address.
		 * If none on this machine then drop if strictly routed,
		 * or do nothing if loosely routed.
		 * Record interface address and bring up next address
		 * component.  If strictly routed make sure next
		 * address is on directly accessible net.
		 */
		case IPOPT_LSRR:
		case IPOPT_SSRR: {
			struct psref psref;
			if (ip_allowsrcrt == 0) {
				type = ICMP_UNREACH;
				code = ICMP_UNREACH_NET_PROHIB;
				goto bad;
			}
			if (optlen < IPOPT_OFFSET + sizeof(*cp)) {
				code = &cp[IPOPT_OLEN] - (u_char *)ip;
				goto bad;
			}
			if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
				code = &cp[IPOPT_OFFSET] - (u_char *)ip;
				goto bad;
			}
			ipaddr.sin_addr = ip->ip_dst;

			s = pserialize_read_enter();
			ifa = ifa_ifwithaddr(sintosa(&ipaddr));
			if (ifa == NULL) {
				pserialize_read_exit(s);
				if (opt == IPOPT_SSRR) {
					type = ICMP_UNREACH;
					code = ICMP_UNREACH_SRCFAIL;
					goto bad;
				}
				/*
				 * Loose routing, and not at next destination
				 * yet; nothing to do except forward.
				 */
				break;
			}
			pserialize_read_exit(s);

			off--;			/* 0 origin */
			if ((off + sizeof(struct in_addr)) > optlen) {
				/*
				 * End of source route.  Should be for us.
				 */
				save_rte(cp, ip->ip_src);
				break;
			}
			/*
			 * locate outgoing interface
			 */
			memcpy((void *)&ipaddr.sin_addr, (void *)(cp + off),
			    sizeof(ipaddr.sin_addr));
			if (opt == IPOPT_SSRR) {
				ifa = ifa_ifwithladdr_psref(sintosa(&ipaddr),
				    &psref);
				if (ifa != NULL)
					ia = ifatoia(ifa);
				else
					ia = NULL;
			} else {
				ia = ip_rtaddr(ipaddr.sin_addr, &psref);
			}
			if (ia == NULL) {
				type = ICMP_UNREACH;
				code = ICMP_UNREACH_SRCFAIL;
				goto bad;
			}
			ip->ip_dst = ipaddr.sin_addr;
			bcopy((void *)&ia->ia_addr.sin_addr,
			    (void *)(cp + off), sizeof(struct in_addr));
			ia4_release(ia, &psref);
			cp[IPOPT_OFFSET] += sizeof(struct in_addr);
			/*
			 * Let ip_intr's mcast routing check handle mcast pkts
			 */
			forward = !IN_MULTICAST(ip->ip_dst.s_addr);
			break;
		    }

		case IPOPT_RR: {
			struct psref psref;
			if (optlen < IPOPT_OFFSET + sizeof(*cp)) {
				code = &cp[IPOPT_OLEN] - (u_char *)ip;
				goto bad;
			}
			if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
				code = &cp[IPOPT_OFFSET] - (u_char *)ip;
				goto bad;
			}
			/*
			 * If no space remains, ignore.
			 */
			off--;			/* 0 origin */
			if ((off + sizeof(struct in_addr)) > optlen)
				break;
			memcpy((void *)&ipaddr.sin_addr, (void *)(&ip->ip_dst),
			    sizeof(ipaddr.sin_addr));
			/*
			 * locate outgoing interface; if we're the destination,
			 * use the incoming interface (should be same).
			 */
			ifa = ifa_ifwithaddr_psref(sintosa(&ipaddr), &psref);
			if (ifa == NULL) {
				ia = ip_rtaddr(ipaddr.sin_addr, &psref);
				if (ia == NULL) {
					type = ICMP_UNREACH;
					code = ICMP_UNREACH_HOST;
					goto bad;
				}
			} else {
				ia = ifatoia(ifa);
			}
			bcopy((void *)&ia->ia_addr.sin_addr,
			    (void *)(cp + off), sizeof(struct in_addr));
			ia4_release(ia, &psref);
			cp[IPOPT_OFFSET] += sizeof(struct in_addr);
			break;
		    }

		case IPOPT_TS:
			code = cp - (u_char *)ip;
			ipt = (struct ip_timestamp *)cp;
			if (ipt->ipt_len < 4 || ipt->ipt_len > 40) {
				code = (u_char *)&ipt->ipt_len - (u_char *)ip;
				goto bad;
			}
			if (ipt->ipt_ptr < 5) {
				code = (u_char *)&ipt->ipt_ptr - (u_char *)ip;
				goto bad;
			}
			if (ipt->ipt_ptr > ipt->ipt_len - sizeof (int32_t)) {
				if (++ipt->ipt_oflw == 0) {
					code = (u_char *)&ipt->ipt_ptr -
					    (u_char *)ip;
					goto bad;
				}
				break;
			}
			cp0 = (cp + ipt->ipt_ptr - 1);
			switch (ipt->ipt_flg) {

			case IPOPT_TS_TSONLY:
				break;

			case IPOPT_TS_TSANDADDR: {
				struct ifnet *rcvif;
				int _s, _ss;

				if (ipt->ipt_ptr - 1 + sizeof(n_time) +
				    sizeof(struct in_addr) > ipt->ipt_len) {
					code = (u_char *)&ipt->ipt_ptr -
					    (u_char *)ip;
					goto bad;
				}
				ipaddr.sin_addr = dst;
				_ss = pserialize_read_enter();
				rcvif = m_get_rcvif(m, &_s);
				ifa = ifaof_ifpforaddr(sintosa(&ipaddr), rcvif);
				m_put_rcvif(rcvif, &_s);
				if (ifa == NULL) {
					pserialize_read_exit(_ss);
					break;
				}
				ia = ifatoia(ifa);
				bcopy(&ia->ia_addr.sin_addr,
				    cp0, sizeof(struct in_addr));
				pserialize_read_exit(_ss);
				ipt->ipt_ptr += sizeof(struct in_addr);
				break;
			}

			case IPOPT_TS_PRESPEC:
				if (ipt->ipt_ptr - 1 + sizeof(n_time) +
				    sizeof(struct in_addr) > ipt->ipt_len) {
					code = (u_char *)&ipt->ipt_ptr -
					    (u_char *)ip;
					goto bad;
				}
				memcpy(&ipaddr.sin_addr, cp0,
				    sizeof(struct in_addr));
				s = pserialize_read_enter();
				ifa = ifa_ifwithaddr(sintosa(&ipaddr));
				if (ifa == NULL) {
					pserialize_read_exit(s);
					continue;
				}
				pserialize_read_exit(s);
				ipt->ipt_ptr += sizeof(struct in_addr);
				break;

			default:
				/* XXX can't take &ipt->ipt_flg */
				code = (u_char *)&ipt->ipt_ptr -
				    (u_char *)ip + 1;
				goto bad;
			}
			ntime = iptime();
			cp0 = (u_char *) &ntime; /* XXX grumble, GCC... */
			memmove((char *)cp + ipt->ipt_ptr - 1, cp0,
			    sizeof(n_time));
			ipt->ipt_ptr += sizeof(n_time);
		}
	}
	if (forward) {
		struct ifnet *rcvif;
		struct psref _psref;

		if (ip_forwsrcrt == 0) {
			type = ICMP_UNREACH;
			code = ICMP_UNREACH_SRCFAIL;
			goto bad;
		}

		rcvif = m_get_rcvif_psref(m, &_psref);
		if (__predict_false(rcvif == NULL)) {
			type = ICMP_UNREACH;
			code = ICMP_UNREACH_HOST;
			goto bad;
		}
		ip_forward(m, 1, rcvif);
		m_put_rcvif_psref(rcvif, &_psref);
		return true;
	}
	return false;
bad:
	icmp_error(m, type, code, 0, 0);
	IP_STATINC(IP_STAT_BADOPTIONS);
	return true;
}

/*
 * ip_rtaddr: given address of next destination (final or next hop),
 * return internet address info of interface to be used to get there.
 */
static struct in_ifaddr *
ip_rtaddr(struct in_addr dst, struct psref *psref)
{
	struct rtentry *rt;
	union {
		struct sockaddr		dst;
		struct sockaddr_in	dst4;
	} u;
	struct route *ro;

	sockaddr_in_init(&u.dst4, &dst, 0);

	ro = percpu_getref(ipforward_rt_percpu);
	rt = rtcache_lookup(ro, &u.dst);
	if (rt == NULL) {
		percpu_putref(ipforward_rt_percpu);
		return NULL;
	}

	ia4_acquire(ifatoia(rt->rt_ifa), psref);
	rtcache_unref(rt, ro);
	percpu_putref(ipforward_rt_percpu);

	return ifatoia(rt->rt_ifa);
}

/*
 * save_rte: save incoming source route for use in replies, to be picked
 * up later by ip_srcroute if the receiver is interested.
 */
static void
save_rte(u_char *option, struct in_addr dst)
{
	unsigned olen;

	olen = option[IPOPT_OLEN];
	if (olen > sizeof(ip_srcrt) - (1 + sizeof(dst)))
		return;
	memcpy((void *)ip_srcrt.srcopt, (void *)option, olen);
	ip_nhops = (olen - IPOPT_OFFSET - 1) / sizeof(struct in_addr);
	ip_srcrt.dst = dst;
}

/*
 * Retrieve incoming source route for use in replies,
 * in the same form used by setsockopt.
 * The first hop is placed before the options, will be removed later.
 */
struct mbuf *
ip_srcroute(void)
{
	struct in_addr *p, *q;
	struct mbuf *m;

	if (ip_nhops == 0)
		return NULL;
	m = m_get(M_DONTWAIT, MT_SOOPTS);
	if (m == 0)
		return NULL;

	MCLAIM(m, &inetdomain.dom_mowner);
#define OPTSIZ	(sizeof(ip_srcrt.nop) + sizeof(ip_srcrt.srcopt))

	/* length is (nhops+1)*sizeof(addr) + sizeof(nop + srcrt header) */
	m->m_len = ip_nhops * sizeof(struct in_addr) + sizeof(struct in_addr) +
	    OPTSIZ;

	/*
	 * First save first hop for return route
	 */
	p = &ip_srcrt.route[ip_nhops - 1];
	*(mtod(m, struct in_addr *)) = *p--;

	/*
	 * Copy option fields and padding (nop) to mbuf.
	 */
	ip_srcrt.nop = IPOPT_NOP;
	ip_srcrt.srcopt[IPOPT_OFFSET] = IPOPT_MINOFF;
	memmove(mtod(m, char *) + sizeof(struct in_addr), &ip_srcrt.nop,
	    OPTSIZ);
	q = (struct in_addr *)(mtod(m, char *) +
	    sizeof(struct in_addr) + OPTSIZ);
#undef OPTSIZ
	/*
	 * Record return path as an IP source route,
	 * reversing the path (pointers are now aligned).
	 */
	while (p >= ip_srcrt.route) {
		*q++ = *p--;
	}
	/*
	 * Last hop goes to final destination.
	 */
	*q = ip_srcrt.dst;
	return (m);
}

const int inetctlerrmap[PRC_NCMDS] = {
	[PRC_MSGSIZE] = EMSGSIZE,
	[PRC_HOSTDEAD] = EHOSTDOWN,
	[PRC_HOSTUNREACH] = EHOSTUNREACH,
	[PRC_UNREACH_NET] = EHOSTUNREACH,
	[PRC_UNREACH_HOST] = EHOSTUNREACH,
	[PRC_UNREACH_PROTOCOL] = ECONNREFUSED,
	[PRC_UNREACH_PORT] = ECONNREFUSED,
	[PRC_UNREACH_SRCFAIL] = EHOSTUNREACH,
	[PRC_PARAMPROB] = ENOPROTOOPT,
};

void
ip_fasttimo(void)
{
	if (ip_drainwanted) {
		ip_drain();
		ip_drainwanted = 0;
	}
}

void
ip_drainstub(void)
{
	ip_drainwanted = 1;
}

/*
 * Forward a packet.  If some error occurs return the sender
 * an icmp packet.  Note we can't always generate a meaningful
 * icmp message because icmp doesn't have a large enough repertoire
 * of codes and types.
 *
 * If not forwarding, just drop the packet.  This could be confusing
 * if ipforwarding was zero but some routing protocol was advancing
 * us as a gateway to somewhere.  However, we must let the routing
 * protocol deal with that.
 *
 * The srcrt parameter indicates whether the packet is being forwarded
 * via a source route.
 */
static void
ip_forward(struct mbuf *m, int srcrt, struct ifnet *rcvif)
{
	struct ip *ip = mtod(m, struct ip *);
	struct rtentry *rt;
	int error, type = 0, code = 0, destmtu = 0;
	struct mbuf *mcopy;
	n_long dest;
	union {
		struct sockaddr		dst;
		struct sockaddr_in	dst4;
	} u;
	uint64_t *ips;
	struct route *ro;

	KASSERTMSG(cpu_softintr_p(), "ip_forward: not in the software "
	    "interrupt handler; synchronization assumptions violated");

	/*
	 * We are now in the output path.
	 */
	MCLAIM(m, &ip_tx_mowner);

	/*
	 * Clear any in-bound checksum flags for this packet.
	 */
	m->m_pkthdr.csum_flags = 0;

	dest = 0;
	if (m->m_flags & (M_BCAST|M_MCAST) || in_canforward(ip->ip_dst) == 0) {
		IP_STATINC(IP_STAT_CANTFORWARD);
		m_freem(m);
		return;
	}

	if (ip->ip_ttl <= IPTTLDEC) {
		icmp_error(m, ICMP_TIMXCEED, ICMP_TIMXCEED_INTRANS, dest, 0);
		return;
	}

	sockaddr_in_init(&u.dst4, &ip->ip_dst, 0);

	ro = percpu_getref(ipforward_rt_percpu);
	rt = rtcache_lookup(ro, &u.dst);
	if (rt == NULL) {
		percpu_putref(ipforward_rt_percpu);
		icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_NET, dest, 0);
		return;
	}

	/*
	 * Save at most 68 bytes of the packet in case
	 * we need to generate an ICMP message to the src.
	 * Pullup to avoid sharing mbuf cluster between m and mcopy.
	 */
	mcopy = m_copym(m, 0, imin(ntohs(ip->ip_len), 68), M_DONTWAIT);
	if (mcopy)
		mcopy = m_pullup(mcopy, ip->ip_hl << 2);

	ip->ip_ttl -= IPTTLDEC;

	/*
	 * If forwarding packet using same interface that it came in on,
	 * perhaps should send a redirect to sender to shortcut a hop.
	 * Only send redirect if source is sending directly to us,
	 * and if packet was not source routed (or has any options).
	 * Also, don't send redirect if forwarding using a default route
	 * or a route modified by a redirect.
	 */
	if (rt->rt_ifp == rcvif &&
	    (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0 &&
	    !in_nullhost(satocsin(rt_getkey(rt))->sin_addr) &&
	    ipsendredirects && !srcrt) {
		if (rt->rt_ifa &&
		    (ip->ip_src.s_addr & ifatoia(rt->rt_ifa)->ia_subnetmask) ==
		    ifatoia(rt->rt_ifa)->ia_subnet) {
			if (rt->rt_flags & RTF_GATEWAY)
				dest = satosin(rt->rt_gateway)->sin_addr.s_addr;
			else
				dest = ip->ip_dst.s_addr;
			/*
			 * Router requirements says to only send host
			 * redirects.
			 */
			type = ICMP_REDIRECT;
			code = ICMP_REDIRECT_HOST;
		}
	}
	rtcache_unref(rt, ro);

	error = ip_output(m, NULL, ro,
	    (IP_FORWARDING | (ip_directedbcast ? IP_ALLOWBROADCAST : 0)),
	    NULL, NULL);

	if (error) {
		IP_STATINC(IP_STAT_CANTFORWARD);
		goto error;
	}

	ips = IP_STAT_GETREF();
	ips[IP_STAT_FORWARD]++;

	if (type) {
		ips[IP_STAT_REDIRECTSENT]++;
		IP_STAT_PUTREF();
		goto redirect;
	}

	IP_STAT_PUTREF();
	if (mcopy) {
#ifdef GATEWAY
		if (mcopy->m_flags & M_CANFASTFWD)
			ipflow_create(ro, mcopy);
#endif
		m_freem(mcopy);
	}

	percpu_putref(ipforward_rt_percpu);
	return;

redirect:
error:
	if (mcopy == NULL) {
		percpu_putref(ipforward_rt_percpu);
		return;
	}

	switch (error) {

	case 0:				/* forwarded, but need redirect */
		/* type, code set above */
		break;

	case ENETUNREACH:		/* shouldn't happen, checked above */
	case EHOSTUNREACH:
	case ENETDOWN:
	case EHOSTDOWN:
	default:
		type = ICMP_UNREACH;
		code = ICMP_UNREACH_HOST;
		break;

	case EMSGSIZE:
		type = ICMP_UNREACH;
		code = ICMP_UNREACH_NEEDFRAG;

		if ((rt = rtcache_validate(ro)) != NULL) {
			destmtu = rt->rt_ifp->if_mtu;
			rtcache_unref(rt, ro);
		}
#ifdef IPSEC
		if (ipsec_used)
			(void)ipsec4_forward(mcopy, &destmtu);
#endif
		IP_STATINC(IP_STAT_CANTFRAG);
		break;

	case ENOBUFS:
		/*
		 * Do not generate ICMP_SOURCEQUENCH as required in RFC 1812,
		 * Requirements for IP Version 4 Routers.  Source quench can
		 * big problem under DoS attacks or if the underlying
		 * interface is rate-limited.
		 */
		if (mcopy)
			m_freem(mcopy);
		percpu_putref(ipforward_rt_percpu);
		return;
	}
	icmp_error(mcopy, type, code, dest, destmtu);
	percpu_putref(ipforward_rt_percpu);
}

void
ip_savecontrol(struct inpcb *inp, struct mbuf **mp, struct ip *ip,
    struct mbuf *m)
{
	struct socket *so = inp->inp_socket;
	ifnet_t *ifp;
	int inpflags = inp->inp_flags;
	struct psref psref;

	ifp = m_get_rcvif_psref(m, &psref);
	if (__predict_false(ifp == NULL))
		return; /* XXX should report error? */

	if (so->so_options & SO_TIMESTAMP
#ifdef SO_OTIMESTAMP
	    || so->so_options & SO_OTIMESTAMP
#endif
	    ) {
		struct timeval tv;

		microtime(&tv);
#ifdef SO_OTIMESTAMP
		if (so->so_options & SO_OTIMESTAMP) {
			struct timeval50 tv50;
			timeval_to_timeval50(&tv, &tv50);
			*mp = sbcreatecontrol((void *) &tv50, sizeof(tv50),
			    SCM_OTIMESTAMP, SOL_SOCKET);
		} else
#endif
		*mp = sbcreatecontrol((void *) &tv, sizeof(tv),
		    SCM_TIMESTAMP, SOL_SOCKET);
		if (*mp)
			mp = &(*mp)->m_next;
	}
	if (inpflags & INP_RECVDSTADDR) {
		*mp = sbcreatecontrol((void *) &ip->ip_dst,
		    sizeof(struct in_addr), IP_RECVDSTADDR, IPPROTO_IP);
		if (*mp)
			mp = &(*mp)->m_next;
	}
	if (inpflags & INP_RECVPKTINFO) {
		struct in_pktinfo ipi;
		ipi.ipi_addr = ip->ip_src;
		ipi.ipi_ifindex = ifp->if_index;
		*mp = sbcreatecontrol((void *) &ipi,
		    sizeof(ipi), IP_RECVPKTINFO, IPPROTO_IP);
		if (*mp)
			mp = &(*mp)->m_next;
	}
	if (inpflags & INP_PKTINFO) {
		struct in_pktinfo ipi;
		ipi.ipi_addr = ip->ip_dst;
		ipi.ipi_ifindex = ifp->if_index;
		*mp = sbcreatecontrol((void *) &ipi,
		    sizeof(ipi), IP_PKTINFO, IPPROTO_IP);
		if (*mp)
			mp = &(*mp)->m_next;
	}
	if (inpflags & INP_RECVIF) {
		struct sockaddr_dl sdl;

		sockaddr_dl_init(&sdl, sizeof(sdl), ifp->if_index, 0, NULL, 0,
		    NULL, 0);
		*mp = sbcreatecontrol(&sdl, sdl.sdl_len, IP_RECVIF, IPPROTO_IP);
		if (*mp)
			mp = &(*mp)->m_next;
	}
	if (inpflags & INP_RECVTTL) {
		*mp = sbcreatecontrol((void *) &ip->ip_ttl,
		    sizeof(uint8_t), IP_RECVTTL, IPPROTO_IP);
		if (*mp)
			mp = &(*mp)->m_next;
	}
	m_put_rcvif_psref(ifp, &psref);
}

/*
 * sysctl helper routine for net.inet.ip.forwsrcrt.
 */
static int
sysctl_net_inet_ip_forwsrcrt(SYSCTLFN_ARGS)
{
	int error, tmp;
	struct sysctlnode node;

	node = *rnode;
	tmp = ip_forwsrcrt;
	node.sysctl_data = &tmp;
	error = sysctl_lookup(SYSCTLFN_CALL(&node));
	if (error || newp == NULL)
		return (error);

	error = kauth_authorize_network(l->l_cred, KAUTH_NETWORK_FORWSRCRT,
	    0, NULL, NULL, NULL);
	if (error)
		return (error);

	ip_forwsrcrt = tmp;

	return (0);
}

/*
 * sysctl helper routine for net.inet.ip.mtudisctimeout.  checks the
 * range of the new value and tweaks timers if it changes.
 */
static int
sysctl_net_inet_ip_pmtudto(SYSCTLFN_ARGS)
{
	int error, tmp;
	struct sysctlnode node;

	node = *rnode;
	tmp = ip_mtudisc_timeout;
	node.sysctl_data = &tmp;
	error = sysctl_lookup(SYSCTLFN_CALL(&node));
	if (error || newp == NULL)
		return (error);
	if (tmp < 0)
		return (EINVAL);

	mutex_enter(softnet_lock);

	ip_mtudisc_timeout = tmp;
	rt_timer_queue_change(ip_mtudisc_timeout_q, ip_mtudisc_timeout);

	mutex_exit(softnet_lock);

	return (0);
}

static int
sysctl_net_inet_ip_stats(SYSCTLFN_ARGS)
{

	return (NETSTAT_SYSCTL(ipstat_percpu, IP_NSTATS));
}

static void
sysctl_net_inet_ip_setup(struct sysctllog **clog)
{
	sysctl_createv(clog, 0, NULL, NULL,
		       CTLFLAG_PERMANENT,
		       CTLTYPE_NODE, "inet",
		       SYSCTL_DESCR("PF_INET related settings"),
		       NULL, 0, NULL, 0,
		       CTL_NET, PF_INET, CTL_EOL);
	sysctl_createv(clog, 0, NULL, NULL,
		       CTLFLAG_PERMANENT,
		       CTLTYPE_NODE, "ip",
		       SYSCTL_DESCR("IPv4 related settings"),
		       NULL, 0, NULL, 0,
		       CTL_NET, PF_INET, IPPROTO_IP, CTL_EOL);

	sysctl_createv(clog, 0, NULL, NULL,
		       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
		       CTLTYPE_INT, "forwarding",
		       SYSCTL_DESCR("Enable forwarding of INET datagrams"),
		       NULL, 0, &ipforwarding, 0,
		       CTL_NET, PF_INET, IPPROTO_IP,
		       IPCTL_FORWARDING, CTL_EOL);
	sysctl_createv(clog, 0, NULL, NULL,
		       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
		       CTLTYPE_INT, "redirect",
		       SYSCTL_DESCR("Enable sending of ICMP redirect messages"),
		       NULL, 0, &ipsendredirects, 0,
		       CTL_NET, PF_INET, IPPROTO_IP,
		       IPCTL_SENDREDIRECTS, CTL_EOL);
	sysctl_createv(clog, 0, NULL, NULL,
		       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
		       CTLTYPE_INT, "ttl",
		       SYSCTL_DESCR("Default TTL for an INET datagram"),
		       NULL, 0, &ip_defttl, 0,
		       CTL_NET, PF_INET, IPPROTO_IP,
		       IPCTL_DEFTTL, CTL_EOL);
#ifdef IPCTL_DEFMTU
	sysctl_createv(clog, 0, NULL, NULL,
		       CTLFLAG_PERMANENT /* |CTLFLAG_READWRITE? */,
		       CTLTYPE_INT, "mtu",
		       SYSCTL_DESCR("Default MTA for an INET route"),
		       NULL, 0, &ip_mtu, 0,
		       CTL_NET, PF_INET, IPPROTO_IP,
		       IPCTL_DEFMTU, CTL_EOL);
#endif /* IPCTL_DEFMTU */
	sysctl_createv(clog, 0, NULL, NULL,
		       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
		       CTLTYPE_INT, "forwsrcrt",
		       SYSCTL_DESCR("Enable forwarding of source-routed "
				    "datagrams"),
		       sysctl_net_inet_ip_forwsrcrt, 0, &ip_forwsrcrt, 0,
		       CTL_NET, PF_INET, IPPROTO_IP,
		       IPCTL_FORWSRCRT, CTL_EOL);
	sysctl_createv(clog, 0, NULL, NULL,
		       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
		       CTLTYPE_INT, "directed-broadcast",
		       SYSCTL_DESCR("Enable forwarding of broadcast datagrams"),
		       NULL, 0, &ip_directedbcast, 0,
		       CTL_NET, PF_INET, IPPROTO_IP,
		       IPCTL_DIRECTEDBCAST, CTL_EOL);
	sysctl_createv(clog, 0, NULL, NULL,
		       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
		       CTLTYPE_INT, "allowsrcrt",
		       SYSCTL_DESCR("Accept source-routed datagrams"),
		       NULL, 0, &ip_allowsrcrt, 0,
		       CTL_NET, PF_INET, IPPROTO_IP,
		       IPCTL_ALLOWSRCRT, CTL_EOL);

	sysctl_createv(clog, 0, NULL, NULL,
		       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
		       CTLTYPE_INT, "mtudisc",
		       SYSCTL_DESCR("Use RFC1191 Path MTU Discovery"),
		       NULL, 0, &ip_mtudisc, 0,
		       CTL_NET, PF_INET, IPPROTO_IP,
		       IPCTL_MTUDISC, CTL_EOL);
	sysctl_createv(clog, 0, NULL, NULL,
		       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
		       CTLTYPE_INT, "anonportmin",
		       SYSCTL_DESCR("Lowest ephemeral port number to assign"),
		       sysctl_net_inet_ip_ports, 0, &anonportmin, 0,
		       CTL_NET, PF_INET, IPPROTO_IP,
		       IPCTL_ANONPORTMIN, CTL_EOL);
	sysctl_createv(clog, 0, NULL, NULL,
		       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
		       CTLTYPE_INT, "anonportmax",
		       SYSCTL_DESCR("Highest ephemeral port number to assign"),
		       sysctl_net_inet_ip_ports, 0, &anonportmax, 0,
		       CTL_NET, PF_INET, IPPROTO_IP,
		       IPCTL_ANONPORTMAX, CTL_EOL);
	sysctl_createv(clog, 0, NULL, NULL,
		       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
		       CTLTYPE_INT, "mtudisctimeout",
		       SYSCTL_DESCR("Lifetime of a Path MTU Discovered route"),
		       sysctl_net_inet_ip_pmtudto, 0, (void *)&ip_mtudisc_timeout, 0,
		       CTL_NET, PF_INET, IPPROTO_IP,
		       IPCTL_MTUDISCTIMEOUT, CTL_EOL);
#ifndef IPNOPRIVPORTS
	sysctl_createv(clog, 0, NULL, NULL,
		       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
		       CTLTYPE_INT, "lowportmin",
		       SYSCTL_DESCR("Lowest privileged ephemeral port number "
				    "to assign"),
		       sysctl_net_inet_ip_ports, 0, &lowportmin, 0,
		       CTL_NET, PF_INET, IPPROTO_IP,
		       IPCTL_LOWPORTMIN, CTL_EOL);
	sysctl_createv(clog, 0, NULL, NULL,
		       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
		       CTLTYPE_INT, "lowportmax",
		       SYSCTL_DESCR("Highest privileged ephemeral port number "
				    "to assign"),
		       sysctl_net_inet_ip_ports, 0, &lowportmax, 0,
		       CTL_NET, PF_INET, IPPROTO_IP,
		       IPCTL_LOWPORTMAX, CTL_EOL);
#endif /* IPNOPRIVPORTS */
#if NGRE > 0
	sysctl_createv(clog, 0, NULL, NULL,
		       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
		       CTLTYPE_INT, "grettl",
		       SYSCTL_DESCR("Default TTL for a gre tunnel datagram"),
		       NULL, 0, &ip_gre_ttl, 0,
		       CTL_NET, PF_INET, IPPROTO_IP,
		       IPCTL_GRE_TTL, CTL_EOL);
#endif /* NGRE */
	sysctl_createv(clog, 0, NULL, NULL,
		       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
		       CTLTYPE_INT, "checkinterface",
		       SYSCTL_DESCR("Enable receive side of Strong ES model "
				    "from RFC1122"),
		       NULL, 0, &ip_checkinterface, 0,
		       CTL_NET, PF_INET, IPPROTO_IP,
		       IPCTL_CHECKINTERFACE, CTL_EOL);
	sysctl_createv(clog, 0, NULL, NULL,
		       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
		       CTLTYPE_INT, "random_id",
		       SYSCTL_DESCR("Assign random ip_id values"),
		       NULL, 0, &ip_do_randomid, 0,
		       CTL_NET, PF_INET, IPPROTO_IP,
		       IPCTL_RANDOMID, CTL_EOL);
	sysctl_createv(clog, 0, NULL, NULL,
		       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
		       CTLTYPE_INT, "do_loopback_cksum",
		       SYSCTL_DESCR("Perform IP checksum on loopback"),
		       NULL, 0, &ip_do_loopback_cksum, 0,
		       CTL_NET, PF_INET, IPPROTO_IP,
		       IPCTL_LOOPBACKCKSUM, CTL_EOL);
	sysctl_createv(clog, 0, NULL, NULL,
		       CTLFLAG_PERMANENT,
		       CTLTYPE_STRUCT, "stats",
		       SYSCTL_DESCR("IP statistics"),
		       sysctl_net_inet_ip_stats, 0, NULL, 0,
		       CTL_NET, PF_INET, IPPROTO_IP, IPCTL_STATS,
		       CTL_EOL);
#if NARP
	sysctl_createv(clog, 0, NULL, NULL,
		       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
		       CTLTYPE_INT, "dad_count",
		       SYSCTL_DESCR("Number of Duplicate Address Detection "
				    "probes to send"),
		       NULL, 0, &ip_dad_count, 0,
		       CTL_NET, PF_INET, IPPROTO_IP,
		       IPCTL_DAD_COUNT, CTL_EOL);
#endif

	/* anonportalgo RFC6056 subtree */
	const struct sysctlnode *portalgo_node;
	sysctl_createv(clog, 0, NULL, &portalgo_node,
		       CTLFLAG_PERMANENT,
		       CTLTYPE_NODE, "anonportalgo",
		       SYSCTL_DESCR("Anonymous Port Algorithm Selection (RFC 6056)"),
	    	       NULL, 0, NULL, 0,
		       CTL_NET, PF_INET, IPPROTO_IP, CTL_CREATE, CTL_EOL);
	sysctl_createv(clog, 0, &portalgo_node, NULL,
		       CTLFLAG_PERMANENT,
		       CTLTYPE_STRING, "available",
		       SYSCTL_DESCR("available algorithms"),
		       sysctl_portalgo_available, 0, NULL, PORTALGO_MAXLEN,
		       CTL_CREATE, CTL_EOL);
	sysctl_createv(clog, 0, &portalgo_node, NULL,
		       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
		       CTLTYPE_STRING, "selected",
		       SYSCTL_DESCR("selected algorithm"),
		       sysctl_portalgo_selected4, 0, NULL, PORTALGO_MAXLEN,
		       CTL_CREATE, CTL_EOL);
	sysctl_createv(clog, 0, &portalgo_node, NULL,
		       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
		       CTLTYPE_STRUCT, "reserve",
		       SYSCTL_DESCR("bitmap of reserved ports"),
		       sysctl_portalgo_reserve4, 0, NULL, 0,
		       CTL_CREATE, CTL_EOL);
}

void
ip_statinc(u_int stat)
{

	KASSERT(stat < IP_NSTATS);
	IP_STATINC(stat);
}