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

Revision 1.344, Tue Oct 18 07:30:31 2016 UTC (11 months, 4 weeks ago) by ozaki-r
Branch: MAIN
CVS Tags: pgoyette-localcount-20161104, nick-nhusb-base-20161204
Changes since 1.343: +12 -13 lines

Don't hold global locks if NET_MPSAFE is enabled

If NET_MPSAFE is enabled, don't hold KERNEL_LOCK and softnet_lock in
part of the network stack such as IP forwarding paths. The aim of the
change is to make it easy to test the network stack without the locks
and reduce our local diffs.

By default (i.e., if NET_MPSAFE isn't enabled), the locks are held
as they used to be.

Reviewed by knakahara@

/*	$NetBSD: ip_input.c,v 1.344 2016/10/18 07:30:31 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 1.344 2016/10/18 07:30:31 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);
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;

	ip_mtudisc_timeout_q = rt_timer_queue_create(ip_mtudisc_timeout);
#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:
			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));
			s = pserialize_read_enter();
			if (opt == IPOPT_SSRR) {
				ifa = ifa_ifwithladdr(sintosa(&ipaddr));
				if (ifa != NULL)
					ia = ifatoia(ifa);
				else
					ia = NULL;
			} else {
				ia = ip_rtaddr(ipaddr.sin_addr);
			}
			if (ia == NULL) {
				type = ICMP_UNREACH;
				code = ICMP_UNREACH_SRCFAIL;
				pserialize_read_exit(s);
				goto bad;
			}
			ip->ip_dst = ipaddr.sin_addr;
			bcopy((void *)&ia->ia_addr.sin_addr,
			    (void *)(cp + off), sizeof(struct in_addr));
			pserialize_read_exit(s);
			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:
			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).
			 */
			s = pserialize_read_enter();
			ifa = ifa_ifwithaddr(sintosa(&ipaddr));
			if (ifa == NULL) {
				ia = ip_rtaddr(ipaddr.sin_addr);
				if (ia == NULL) {
					pserialize_read_exit(s);
					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));
			pserialize_read_exit(s);
			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 rtentry *rt;
	union {
		struct sockaddr		dst;
		struct sockaddr_in	dst4;
	} u;
	struct route *ro;

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

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

	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);
	if ((rt = rtcache_lookup(ro, &u.dst)) == 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;
		}
	}

	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;
#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);
}