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

Revision 1.82.2.2.4.3, Tue Nov 30 13:35:31 1999 UTC (14 years, 7 months ago) by itojun
Branch: kame
CVS Tags: kame_141_19991130
Changes since 1.82.2.2.4.2: +25 -10 lines

bring in latest KAME (as of 19991130, KAME/NetBSD141) into kame branch
just for reference purposes.
This commit includes 1.4 -> 1.4.1 sync for kame branch.

The branch does not compile at all (due to the lack of ALTQ and some other
source code).  Please do not try to modify the branch, this is just for
referenre purposes.

synchronization to latest KAME will take place on HEAD branch soon.

/*	$NetBSD: ip_input.c,v 1.82.2.2.4.3 1999/11/30 13:35:31 itojun 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.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the NetBSD
 *	Foundation, Inc. and its contributors.
 * 4. Neither the name of The NetBSD Foundation nor the names of its
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

/*
 * Copyright (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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	@(#)ip_input.c	8.2 (Berkeley) 1/4/94
 */

#include "opt_gateway.h"
#include "opt_pfil_hooks.h"
#include "opt_ipsec.h"
#include "opt_mrouting.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/malloc.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/proc.h>
#include <sys/pool.h>

#include <vm/vm.h>
#include <sys/sysctl.h>

#include <net/if.h>
#include <net/if_dl.h>
#include <net/route.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_var.h>
#include <netinet/ip_var.h>
#include <netinet/ip_icmp.h>
/* just for gif_ttl */
#include <netinet/in_gif.h>
#include "gif.h"

#ifdef IPSEC
#include <netinet6/ipsec.h>
#include <netkey/key.h>
#include <netkey/key_debug.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	0
#endif
#ifndef IPMTUDISCTIMEOUT
#define IPMTUDISCTIMEOUT (10 * 60)	/* as per RFC 1191 */
#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;
u_int	ip_mtudisc_timeout = IPMTUDISCTIMEOUT;
#ifdef DIAGNOSTIC
int	ipprintfs = 0;
#endif

struct rttimer_queue *ip_mtudisc_timeout_q = NULL;

#ifdef ALTQ
int (*altq_input) __P((struct mbuf *, int)) = NULL;
#endif

extern	struct domain inetdomain;
extern	struct protosw inetsw[];
u_char	ip_protox[IPPROTO_MAX];
int	ipqmaxlen = IFQ_MAXLEN;
struct	in_ifaddrhead in_ifaddr;
struct	in_ifaddrhashhead *in_ifaddrhashtbl;
struct	ifqueue ipintrq;
struct	ipstat	ipstat;
u_int16_t	ip_id;
int	ip_defttl;

struct ipqhead ipq;
int	ipq_locked;

static __inline int ipq_lock_try __P((void));
static __inline void ipq_unlock __P((void));

static __inline int
ipq_lock_try()
{
	int s;

	s = splimp();
	if (ipq_locked) {
		splx(s);
		return (0);
	}
	ipq_locked = 1;
	splx(s);
	return (1);
}

static __inline void
ipq_unlock()
{
	int s;

	s = splimp();
	ipq_locked = 0;
	splx(s);
}

#ifdef DIAGNOSTIC
#define	IPQ_LOCK()							\
do {									\
	if (ipq_lock_try() == 0) {					\
		printf("%s:%d: ipq already locked\n", __FILE__, __LINE__); \
		panic("ipq_lock");					\
	}								\
} while (0)
#define	IPQ_LOCK_CHECK()						\
do {									\
	if (ipq_locked == 0) {						\
		printf("%s:%d: ipq lock not held\n", __FILE__, __LINE__); \
		panic("ipq lock check");				\
	}								\
} while (0)
#else
#define	IPQ_LOCK()		(void) ipq_lock_try()
#define	IPQ_LOCK_CHECK()	/* nothing */
#endif

#define	IPQ_UNLOCK()		ipq_unlock()

struct pool ipqent_pool;

/*
 * 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.
 */
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 void save_rte __P((u_char *, struct in_addr));

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

	pool_init(&ipqent_pool, sizeof(struct ipqent), 0, 0, 0, "ipqepl",
	    0, NULL, NULL, M_IPQ);

	pr = pffindproto(PF_INET, IPPROTO_RAW, SOCK_RAW);
	if (pr == 0)
		panic("ip_init");
	for (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;
	LIST_INIT(&ipq);
	ip_id = time.tv_sec & 0xffff;
	ipintrq.ifq_maxlen = ipqmaxlen;
	TAILQ_INIT(&in_ifaddr);
	in_ifaddrhashtbl = 
	    hashinit(IN_IFADDR_HASH_SIZE, M_IFADDR, M_WAITOK, &in_ifaddrhash);
	if (ip_mtudisc != 0)
		ip_mtudisc_timeout_q = 
		    rt_timer_queue_create(ip_mtudisc_timeout);
#ifdef GATEWAY
	ipflow_init();
#endif
}

struct	sockaddr_in ipaddr = { sizeof(ipaddr), AF_INET };
struct	route ipforward_rt;

/*
 * IP software interrupt routine
 */
void
ipintr()
{
	int s;
	struct mbuf *m;

	while (1) {
		s = splimp();
		IF_DEQUEUE(&ipintrq, m);
		splx(s);
		if (m == 0)
			return;
		ip_input(m);
	}
}

/*
 * Ip input routine.  Checksum and byte swap header.  If fragmented
 * try to reassemble.  Process options.  Pass to next level.
 */
void
ip_input(struct mbuf *m)
{
	register struct ip *ip = NULL;
	register struct ipq *fp;
	register struct in_ifaddr *ia;
	register struct ifaddr *ifa;
	struct ipqent *ipqe;
	int hlen = 0, mff, len;
#ifdef PFIL_HOOKS
	struct packet_filter_hook *pfh;
	struct mbuf *m0;
	int rv;
#endif /* PFIL_HOOKS */

#ifdef	DIAGNOSTIC
	if ((m->m_flags & M_PKTHDR) == 0)
		panic("ipintr no HDR");
#endif
#ifdef IPSEC
	/*
	 * should the inner packet be considered authentic?
	 * see comment in ah4_input().
	 */
	if (m) {
		m->m_flags &= ~M_AUTHIPHDR;
		m->m_flags &= ~M_AUTHIPDGM;
	}
#endif
	/*
	 * If no IP addresses have been set yet but the interfaces
	 * are receiving, can't do anything with incoming packets yet.
	 */
	if (in_ifaddr.tqh_first == 0)
		goto bad;
	ipstat.ips_total++;
	if (m->m_len < sizeof (struct ip) &&
	    (m = m_pullup(m, sizeof (struct ip))) == 0) {
		ipstat.ips_toosmall++;
		return;
	}
	ip = mtod(m, struct ip *);
	if (ip->ip_v != IPVERSION) {
		ipstat.ips_badvers++;
		goto bad;
	}
	hlen = ip->ip_hl << 2;
	if (hlen < sizeof(struct ip)) {	/* minimum header length */
		ipstat.ips_badhlen++;
		goto bad;
	}
	if (hlen > m->m_len) {
		if ((m = m_pullup(m, hlen)) == 0) {
			ipstat.ips_badhlen++;
			return;
		}
		ip = mtod(m, struct ip *);
	}
	if (in_cksum(m, hlen) != 0) {
		ipstat.ips_badsum++;
		goto bad;
	}

#ifdef ALTQ
	if (altq_input != NULL && (*altq_input)(m, AF_INET) == 0)
		/* packet is dropped by traffic conditioner */
		return;
#endif
	/*
	 * Convert fields to host representation.
	 */
	NTOHS(ip->ip_len);
	NTOHS(ip->ip_off);
	len = ip->ip_len;

	/*
	 * Check for additional length bogosity
	 */
	if (len < hlen)
	{
	 	ipstat.ips_badlen++;
		goto bad;
	}

	/*
	 * 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) {
		ipstat.ips_tooshort++;
		goto bad;
	}
	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);
	}

#ifdef IPSEC
	/* ipflow (IP fast fowarding) is not compatible with IPsec. */
	m->m_flags &= ~M_CANFASTFWD;
#else
	/*
	 * Assume that we can create a fast-forward IP flow entry
	 * based on this packet.
	 */
	m->m_flags |= M_CANFASTFWD;
#endif

#ifdef PFIL_HOOKS
	/*
	 * 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.
	 */
	m0 = m;
	for (pfh = pfil_hook_get(PFIL_IN); pfh; pfh = pfh->pfil_link.tqe_next)
		if (pfh->pfil_func) {
			rv = pfh->pfil_func(ip, hlen, m->m_pkthdr.rcvif, 0, &m0);
			if (rv)
				return;
			m = m0;
			if (m == NULL)
				return;
			ip = mtod(m, struct ip *);
		}
#endif /* PFIL_HOOKS */

	/*
	 * 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))
		return;

	/*
	 * Check our list of addresses, to see if the packet is for us.
	 */
	INADDR_TO_IA(ip->ip_dst, ia);
	if (ia != NULL)
		goto ours;
	if (m->m_pkthdr.rcvif->if_flags & IFF_BROADCAST) {
		for (ifa = m->m_pkthdr.rcvif->if_addrlist.tqh_first;
		    ifa != NULL; ifa = ifa->ifa_list.tqe_next) {
			if (ifa->ifa_addr->sa_family != AF_INET) continue;
			ia = ifatoia(ifa);
			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 ours;
			/*
			 * An interface with IP address zero accepts
			 * all packets that arrive on that interface.
			 */
			if (in_nullhost(ia->ia_addr.sin_addr))
				goto ours;
		}
	}
	if (IN_MULTICAST(ip->ip_dst.s_addr)) {
		struct in_multi *inm;
#ifdef MROUTING
		extern struct socket *ip_mrouter;

		if (m->m_flags & M_EXT) {
			if ((m = m_pullup(m, hlen)) == 0) {
				ipstat.ips_toosmall++;
				return;
			}
			ip = mtod(m, struct ip *);
		}

		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().)
			 */
			if (ip_mforward(m, m->m_pkthdr.rcvif) != 0) {
				ipstat.ips_cantforward++;
				m_freem(m);
				return;
			}

			/*
			 * 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;
			ipstat.ips_forward++;
		}
#endif
		/*
		 * See if we belong to the destination multicast group on the
		 * arrival interface.
		 */
		IN_LOOKUP_MULTI(ip->ip_dst, m->m_pkthdr.rcvif, inm);
		if (inm == NULL) {
			ipstat.ips_cantforward++;
			m_freem(m);
			return;
		}
		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) {
		ipstat.ips_cantforward++;
		m_freem(m);
	} else
		ip_forward(m, 0);
	return;

ours:
	/*
	 * If offset or IP_MF are set, must reassemble.
	 * Otherwise, nothing need be done.
	 * (We could look in the reassembly queue to see
	 * if the packet was previously fragmented,
	 * but it's not worth the time; just let them time out.)
	 */
	if (ip->ip_off & ~(IP_DF|IP_RF)) {
		/*
		 * Look for queue of fragments
		 * of this datagram.
		 */
		IPQ_LOCK();
		for (fp = ipq.lh_first; fp != NULL; fp = fp->ipq_q.le_next)
			if (ip->ip_id == fp->ipq_id &&
			    in_hosteq(ip->ip_src, fp->ipq_src) &&
			    in_hosteq(ip->ip_dst, fp->ipq_dst) &&
			    ip->ip_p == fp->ipq_p)
				goto found;
		fp = 0;
found:

		/*
		 * Adjust ip_len to not reflect header,
		 * set ipqe_mff if more fragments are expected,
		 * convert offset of this to bytes.
		 */
		ip->ip_len -= hlen;
		mff = (ip->ip_off & IP_MF) != 0;
		if (mff) {
		        /*
		         * Make sure that fragments have a data length
			 * that's a non-zero multiple of 8 bytes.
		         */
			if (ip->ip_len == 0 || (ip->ip_len & 0x7) != 0) {
				ipstat.ips_badfrags++;
				IPQ_UNLOCK();
				goto bad;
			}
		}
		ip->ip_off <<= 3;

		/*
		 * If datagram marked as having more fragments
		 * or if this is not the first fragment,
		 * attempt reassembly; if it succeeds, proceed.
		 */
		if (mff || ip->ip_off) {
			ipstat.ips_fragments++;
			ipqe = pool_get(&ipqent_pool, PR_NOWAIT);
			if (ipqe == NULL) {
				ipstat.ips_rcvmemdrop++;
				IPQ_UNLOCK();
				goto bad;
			}
			ipqe->ipqe_mff = mff;
			ipqe->ipqe_m = m;
			ipqe->ipqe_ip = ip;
			m = ip_reass(ipqe, fp);
			if (m == 0) {
				IPQ_UNLOCK();
				return;
			}
			ipstat.ips_reassembled++;
			ip = mtod(m, struct ip *);
			hlen = ip->ip_hl << 2;
			ip->ip_len += hlen;
		} else
			if (fp)
				ip_freef(fp);
		IPQ_UNLOCK();
	}

	/*
	 * Switch out to protocol's input routine.
	 */
#if IFA_STATS
	ia->ia_ifa.ifa_data.ifad_inbytes += ip->ip_len;
#endif
	ipstat.ips_delivered++;
    {
	int off = hlen, nh = ip->ip_p;

	(*inetsw[ip_protox[nh]].pr_input)(m, off, nh);
	return;
    }
bad:
	m_freem(m);
}

/*
 * Take incoming datagram fragment and try to
 * reassemble it into whole datagram.  If a chain for
 * reassembly of this datagram already exists, then it
 * is given as fp; otherwise have to make a chain.
 */
struct mbuf *
ip_reass(ipqe, fp)
	register struct ipqent *ipqe;
	register struct ipq *fp;
{
	register struct mbuf *m = ipqe->ipqe_m;
	register struct ipqent *nq, *p, *q;
	struct ip *ip;
	struct mbuf *t;
	int hlen = ipqe->ipqe_ip->ip_hl << 2;
	int i, next;

	IPQ_LOCK_CHECK();

	/*
	 * Presence of header sizes in mbufs
	 * would confuse code below.
	 */
	m->m_data += hlen;
	m->m_len -= hlen;

	/*
	 * If first fragment to arrive, create a reassembly queue.
	 */
	if (fp == 0) {
		MALLOC(fp, struct ipq *, sizeof (struct ipq),
		    M_FTABLE, M_NOWAIT);
		if (fp == NULL)
			goto dropfrag;
		LIST_INSERT_HEAD(&ipq, fp, ipq_q);
		fp->ipq_ttl = IPFRAGTTL;
		fp->ipq_p = ipqe->ipqe_ip->ip_p;
		fp->ipq_id = ipqe->ipqe_ip->ip_id;
		LIST_INIT(&fp->ipq_fragq);
		fp->ipq_src = ipqe->ipqe_ip->ip_src;
		fp->ipq_dst = ipqe->ipqe_ip->ip_dst;
		p = NULL;
		goto insert;
	}

	/*
	 * Find a segment which begins after this one does.
	 */
	for (p = NULL, q = fp->ipq_fragq.lh_first; q != NULL;
	    p = q, q = q->ipqe_q.le_next)
		if (q->ipqe_ip->ip_off > ipqe->ipqe_ip->ip_off)
			break;

	/*
	 * If there is a preceding segment, it may provide some of
	 * our data already.  If so, drop the data from the incoming
	 * segment.  If it provides all of our data, drop us.
	 */
	if (p != NULL) {
		i = p->ipqe_ip->ip_off + p->ipqe_ip->ip_len -
		    ipqe->ipqe_ip->ip_off;
		if (i > 0) {
			if (i >= ipqe->ipqe_ip->ip_len)
				goto dropfrag;
			m_adj(ipqe->ipqe_m, i);
			ipqe->ipqe_ip->ip_off += i;
			ipqe->ipqe_ip->ip_len -= i;
		}
	}

	/*
	 * While we overlap succeeding segments trim them or,
	 * if they are completely covered, dequeue them.
	 */
	for (; q != NULL && ipqe->ipqe_ip->ip_off + ipqe->ipqe_ip->ip_len >
	    q->ipqe_ip->ip_off; q = nq) {
		i = (ipqe->ipqe_ip->ip_off + ipqe->ipqe_ip->ip_len) -
		    q->ipqe_ip->ip_off;
		if (i < q->ipqe_ip->ip_len) {
			q->ipqe_ip->ip_len -= i;
			q->ipqe_ip->ip_off += i;
			m_adj(q->ipqe_m, i);
			break;
		}
		nq = q->ipqe_q.le_next;
		m_freem(q->ipqe_m);
		LIST_REMOVE(q, ipqe_q);
		pool_put(&ipqent_pool, q);
	}

insert:
	/*
	 * Stick new segment in its place;
	 * check for complete reassembly.
	 */
	if (p == NULL) {
		LIST_INSERT_HEAD(&fp->ipq_fragq, ipqe, ipqe_q);
	} else {
		LIST_INSERT_AFTER(p, ipqe, ipqe_q);
	}
	next = 0;
	for (p = NULL, q = fp->ipq_fragq.lh_first; q != NULL;
	    p = q, q = q->ipqe_q.le_next) {
		if (q->ipqe_ip->ip_off != next)
			return (0);
		next += q->ipqe_ip->ip_len;
	}
	if (p->ipqe_mff)
		return (0);

	/*
	 * Reassembly is complete.  Check for a bogus message size and
	 * concatenate fragments.
	 */
	q = fp->ipq_fragq.lh_first;
	ip = q->ipqe_ip;
	if ((next + (ip->ip_hl << 2)) > IP_MAXPACKET) {
		ipstat.ips_toolong++;
		ip_freef(fp);
		return (0);
	}
	m = q->ipqe_m;
	t = m->m_next;
	m->m_next = 0;
	m_cat(m, t);
	nq = q->ipqe_q.le_next;
	pool_put(&ipqent_pool, q);
	for (q = nq; q != NULL; q = nq) {
		t = q->ipqe_m;
		nq = q->ipqe_q.le_next;
		pool_put(&ipqent_pool, q);
		m_cat(m, t);
	}

	/*
	 * Create header for new ip packet by
	 * modifying header of first packet;
	 * dequeue and discard fragment reassembly header.
	 * Make header visible.
	 */
	ip->ip_len = next;
	ip->ip_ttl = 0;	/* xxx */
	ip->ip_sum = 0;
	ip->ip_src = fp->ipq_src;
	ip->ip_dst = fp->ipq_dst;
	LIST_REMOVE(fp, ipq_q);
	FREE(fp, M_FTABLE);
	m->m_len += (ip->ip_hl << 2);
	m->m_data -= (ip->ip_hl << 2);
	/* some debugging cruft by sklower, below, will go away soon */
	if (m->m_flags & M_PKTHDR) { /* XXX this should be done elsewhere */
		register int plen = 0;
		for (t = m; t; t = t->m_next)
			plen += t->m_len;
		m->m_pkthdr.len = plen;
	}
	return (m);

dropfrag:
	ipstat.ips_fragdropped++;
	m_freem(m);
	pool_put(&ipqent_pool, ipqe);
	return (0);
}

/*
 * Free a fragment reassembly header and all
 * associated datagrams.
 */
void
ip_freef(fp)
	struct ipq *fp;
{
	register struct ipqent *q, *p;

	IPQ_LOCK_CHECK();

	for (q = fp->ipq_fragq.lh_first; q != NULL; q = p) {
		p = q->ipqe_q.le_next;
		m_freem(q->ipqe_m);
		LIST_REMOVE(q, ipqe_q);
		pool_put(&ipqent_pool, q);
	}
	LIST_REMOVE(fp, ipq_q);
	FREE(fp, M_FTABLE);
}

/*
 * IP timer processing;
 * if a timer expires on a reassembly
 * queue, discard it.
 */
void
ip_slowtimo()
{
	register struct ipq *fp, *nfp;
	int s = splsoftnet();

	IPQ_LOCK();
	for (fp = ipq.lh_first; fp != NULL; fp = nfp) {
		nfp = fp->ipq_q.le_next;
		if (--fp->ipq_ttl == 0) {
			ipstat.ips_fragtimeout++;
			ip_freef(fp);
		}
	}
	IPQ_UNLOCK();
#ifdef GATEWAY
	ipflow_slowtimo();
#endif
	splx(s);
}

/*
 * Drain off all datagram fragments.
 */
void
ip_drain()
{

	/*
	 * We may be called from a device's interrupt context.  If
	 * the ipq is already busy, just bail out now.
	 */
	if (ipq_lock_try() == 0)
		return;

	while (ipq.lh_first != NULL) {
		ipstat.ips_fragdropped++;
		ip_freef(ipq.lh_first);
	}

	IPQ_UNLOCK();
}

/*
 * Do option processing on a datagram,
 * possibly discarding it if bad options are encountered,
 * or forwarding it if source-routed.
 * Returns 1 if packet has been forwarded/freed,
 * 0 if the packet should be processed further.
 */
int
ip_dooptions(m)
	struct mbuf *m;
{
	register struct ip *ip = mtod(m, struct ip *);
	register u_char *cp;
	register struct ip_timestamp *ipt;
	register struct in_ifaddr *ia;
	int opt, optlen, cnt, off, code, type = ICMP_PARAMPROB, forward = 0;
	struct in_addr *sin, dst;
	n_time ntime;

	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 {
			optlen = cp[IPOPT_OLEN];
			if (optlen <= 0 || 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 ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
				code = &cp[IPOPT_OFFSET] - (u_char *)ip;
				goto bad;
			}
			ipaddr.sin_addr = ip->ip_dst;
			ia = ifatoia(ifa_ifwithaddr(sintosa(&ipaddr)));
			if (ia == 0) {
				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;
			}
			off--;			/* 0 origin */
			if (off > optlen - sizeof(struct in_addr)) {
				/*
				 * End of source route.  Should be for us.
				 */
				save_rte(cp, ip->ip_src);
				break;
			}
			/*
			 * locate outgoing interface
			 */
			bcopy((caddr_t)(cp + off), (caddr_t)&ipaddr.sin_addr,
			    sizeof(ipaddr.sin_addr));
			if (opt == IPOPT_SSRR) {
#define	INA	struct in_ifaddr *
#define	SA	struct sockaddr *
			    ia = (INA)ifa_ifwithladdr((SA)&ipaddr);
			} else
				ia = ip_rtaddr(ipaddr.sin_addr);
			if (ia == 0) {
				type = ICMP_UNREACH;
				code = ICMP_UNREACH_SRCFAIL;
				goto bad;
			}
			ip->ip_dst = ipaddr.sin_addr;
			bcopy((caddr_t)&ia->ia_addr.sin_addr,
			    (caddr_t)(cp + off), sizeof(struct in_addr));
			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 ((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 > optlen - sizeof(struct in_addr))
				break;
			bcopy((caddr_t)(&ip->ip_dst), (caddr_t)&ipaddr.sin_addr,
			    sizeof(ipaddr.sin_addr));
			/*
			 * locate outgoing interface; if we're the destination,
			 * use the incoming interface (should be same).
			 */
			if ((ia = (INA)ifa_ifwithaddr((SA)&ipaddr)) == 0 &&
			    (ia = ip_rtaddr(ipaddr.sin_addr)) == 0) {
				type = ICMP_UNREACH;
				code = ICMP_UNREACH_HOST;
				goto bad;
			}
			bcopy((caddr_t)&ia->ia_addr.sin_addr,
			    (caddr_t)(cp + off), sizeof(struct in_addr));
			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 < 5)
				goto bad;
			if (ipt->ipt_ptr > ipt->ipt_len - sizeof (int32_t)) {
				if (++ipt->ipt_oflw == 0)
					goto bad;
				break;
			}
			sin = (struct in_addr *)(cp + ipt->ipt_ptr - 1);
			switch (ipt->ipt_flg) {

			case IPOPT_TS_TSONLY:
				break;

			case IPOPT_TS_TSANDADDR:
				if (ipt->ipt_ptr - 1 + sizeof(n_time) +
				    sizeof(struct in_addr) > ipt->ipt_len)
					goto bad;
				ipaddr.sin_addr = dst;
				ia = (INA)ifaof_ifpforaddr((SA)&ipaddr,
							    m->m_pkthdr.rcvif);
				if (ia == 0)
					continue;
				bcopy((caddr_t)&ia->ia_addr.sin_addr,
				    (caddr_t)sin, sizeof(struct in_addr));
				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)
					goto bad;
				bcopy((caddr_t)sin, (caddr_t)&ipaddr.sin_addr,
				    sizeof(struct in_addr));
				if (ifa_ifwithaddr((SA)&ipaddr) == 0)
					continue;
				ipt->ipt_ptr += sizeof(struct in_addr);
				break;

			default:
				goto bad;
			}
			ntime = iptime();
			bcopy((caddr_t)&ntime, (caddr_t)cp + ipt->ipt_ptr - 1,
			    sizeof(n_time));
			ipt->ipt_ptr += sizeof(n_time);
		}
	}
	if (forward) {
		if (ip_forwsrcrt == 0) {
			type = ICMP_UNREACH;
			code = ICMP_UNREACH_SRCFAIL;
			goto bad;
		}
		ip_forward(m, 1);
		return (1);
	}
	return (0);
bad:
	icmp_error(m, type, code, 0, 0);
	ipstat.ips_badoptions++;
	return (1);
}

/*
 * Given address of next destination (final or next hop),
 * return internet address info of interface to be used to get there.
 */
struct in_ifaddr *
ip_rtaddr(dst)
	 struct in_addr dst;
{
	register struct sockaddr_in *sin;

	sin = satosin(&ipforward_rt.ro_dst);

	if (ipforward_rt.ro_rt == 0 || !in_hosteq(dst, sin->sin_addr)) {
		if (ipforward_rt.ro_rt) {
			RTFREE(ipforward_rt.ro_rt);
			ipforward_rt.ro_rt = 0;
		}
		sin->sin_family = AF_INET;
		sin->sin_len = sizeof(*sin);
		sin->sin_addr = dst;

		rtalloc(&ipforward_rt);
	}
	if (ipforward_rt.ro_rt == 0)
		return ((struct in_ifaddr *)0);
	return (ifatoia(ipforward_rt.ro_rt->rt_ifa));
}

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

	olen = option[IPOPT_OLEN];
#ifdef DIAGNOSTIC
	if (ipprintfs)
		printf("save_rte: olen %d\n", olen);
#endif /* 0 */
	if (olen > sizeof(ip_srcrt) - (1 + sizeof(dst)))
		return;
	bcopy((caddr_t)option, (caddr_t)ip_srcrt.srcopt, 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()
{
	register struct in_addr *p, *q;
	register struct mbuf *m;

	if (ip_nhops == 0)
		return ((struct mbuf *)0);
	m = m_get(M_DONTWAIT, MT_SOOPTS);
	if (m == 0)
		return ((struct mbuf *)0);

#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;
#ifdef DIAGNOSTIC
	if (ipprintfs)
		printf("ip_srcroute: nhops %d mlen %d", ip_nhops, m->m_len);
#endif

	/*
	 * First save first hop for return route
	 */
	p = &ip_srcrt.route[ip_nhops - 1];
	*(mtod(m, struct in_addr *)) = *p--;
#ifdef DIAGNOSTIC
	if (ipprintfs)
		printf(" hops %x", ntohl(mtod(m, struct in_addr *)->s_addr));
#endif

	/*
	 * Copy option fields and padding (nop) to mbuf.
	 */
	ip_srcrt.nop = IPOPT_NOP;
	ip_srcrt.srcopt[IPOPT_OFFSET] = IPOPT_MINOFF;
	bcopy((caddr_t)&ip_srcrt.nop,
	    mtod(m, caddr_t) + sizeof(struct in_addr), OPTSIZ);
	q = (struct in_addr *)(mtod(m, caddr_t) +
	    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) {
#ifdef DIAGNOSTIC
		if (ipprintfs)
			printf(" %x", ntohl(q->s_addr));
#endif
		*q++ = *p--;
	}
	/*
	 * Last hop goes to final destination.
	 */
	*q = ip_srcrt.dst;
#ifdef DIAGNOSTIC
	if (ipprintfs)
		printf(" %x\n", ntohl(q->s_addr));
#endif
	return (m);
}

/*
 * Strip out IP options, at higher
 * level protocol in the kernel.
 * Second argument is buffer to which options
 * will be moved, and return value is their length.
 * XXX should be deleted; last arg currently ignored.
 */
void
ip_stripoptions(m, mopt)
	register struct mbuf *m;
	struct mbuf *mopt;
{
	register int i;
	struct ip *ip = mtod(m, struct ip *);
	register caddr_t opts;
	int olen;

	olen = (ip->ip_hl << 2) - sizeof (struct ip);
	opts = (caddr_t)(ip + 1);
	i = m->m_len - (sizeof (struct ip) + olen);
	bcopy(opts  + olen, opts, (unsigned)i);
	m->m_len -= olen;
	if (m->m_flags & M_PKTHDR)
		m->m_pkthdr.len -= olen;
	ip->ip_len -= olen;
	ip->ip_hl = sizeof (struct ip) >> 2;
}

int inetctlerrmap[PRC_NCMDS] = {
	0,		0,		0,		0,
	0,		EMSGSIZE,	EHOSTDOWN,	EHOSTUNREACH,
	EHOSTUNREACH,	EHOSTUNREACH,	ECONNREFUSED,	ECONNREFUSED,
	EMSGSIZE,	EHOSTUNREACH,	0,		0,
	0,		0,		0,		0,
	ENOPROTOOPT
};

/*
 * 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.
 */
void
ip_forward(m, srcrt)
	struct mbuf *m;
	int srcrt;
{
	register struct ip *ip = mtod(m, struct ip *);
	register struct sockaddr_in *sin;
	register struct rtentry *rt;
	int error, type = 0, code = 0;
	struct mbuf *mcopy;
	n_long dest;
	struct ifnet *destifp;
#ifdef IPSEC
	struct ifnet dummyifp;
#endif

	dest = 0;
#ifdef DIAGNOSTIC
	if (ipprintfs)
		printf("forward: src %2.2x dst %2.2x ttl %x\n",
		    ntohl(ip->ip_src.s_addr),
		    ntohl(ip->ip_dst.s_addr), ip->ip_ttl);
#endif
	if (m->m_flags & M_BCAST || in_canforward(ip->ip_dst) == 0) {
		ipstat.ips_cantforward++;
		m_freem(m);
		return;
	}
	if (ip->ip_ttl <= IPTTLDEC) {
		icmp_error(m, ICMP_TIMXCEED, ICMP_TIMXCEED_INTRANS, dest, 0);
		return;
	}
	ip->ip_ttl -= IPTTLDEC;

	sin = satosin(&ipforward_rt.ro_dst);
	if ((rt = ipforward_rt.ro_rt) == 0 ||
	    !in_hosteq(ip->ip_dst, sin->sin_addr)) {
		if (ipforward_rt.ro_rt) {
			RTFREE(ipforward_rt.ro_rt);
			ipforward_rt.ro_rt = 0;
		}
		sin->sin_family = AF_INET;
		sin->sin_len = sizeof(struct sockaddr_in);
		sin->sin_addr = ip->ip_dst;

		rtalloc(&ipforward_rt);
		if (ipforward_rt.ro_rt == 0) {
			icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, dest, 0);
			return;
		}
		rt = ipforward_rt.ro_rt;
	}

	/*
	 * Save at most 68 bytes of the packet in case
	 * we need to generate an ICMP message to the src.
	 */
	mcopy = m_copy(m, 0, imin((int)ip->ip_len, 68));

	/*
	 * 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 == m->m_pkthdr.rcvif &&
	    (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0 &&
	    !in_nullhost(satosin(rt_key(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;
#ifdef DIAGNOSTIC
			if (ipprintfs)
				printf("redirect (%d) to %x\n", code,
				    (u_int32_t)dest);
#endif
		}
	}

#ifdef IPSEC
	m->m_pkthdr.rcvif = NULL;
#endif /*IPSEC*/
	error = ip_output(m, (struct mbuf *)0, &ipforward_rt,
	    (IP_FORWARDING | (ip_directedbcast ? IP_ALLOWBROADCAST : 0)), 0);
	if (error)
		ipstat.ips_cantforward++;
	else {
		ipstat.ips_forward++;
		if (type)
			ipstat.ips_redirectsent++;
		else {
			if (mcopy) {
#ifdef GATEWAY
				if (mcopy->m_flags & M_CANFASTFWD)
					ipflow_create(&ipforward_rt, mcopy);
#endif
				m_freem(mcopy);
			}
			return;
		}
	}
	if (mcopy == NULL)
		return;
	destifp = NULL;

	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;
#ifndef IPSEC
		if (ipforward_rt.ro_rt)
			destifp = ipforward_rt.ro_rt->rt_ifp;
#else
		/*
		 * If the packet is routed over IPsec tunnel, tell the
		 * originator the tunnel MTU.
		 *	tunnel MTU = if MTU - sizeof(IP) - ESP/AH hdrsiz
		 * XXX quickhack!!!
		 */
		if (ipforward_rt.ro_rt) {
			struct secpolicy *sp;
			int ipsecerror;
			int ipsechdr;
			struct route *ro;

			sp = ipsec4_getpolicybyaddr(mcopy,
			                            IPSEC_DIR_OUTBOUND,
			                            IP_FORWARDING,
			                            &ipsecerror);

			if (sp == NULL)
				destifp = ipforward_rt.ro_rt->rt_ifp;
			else {
				/* count IPsec header size */
				ipsechdr = ipsec4_hdrsiz(mcopy,
				                         IPSEC_DIR_OUTBOUND,
				                         NULL);

				/*
				 * find the correct route for outer IPv4
				 * header, compute tunnel MTU.
				 *
				 * XXX BUG ALERT
				 * The "dummyifp" code relies upon the fact
				 * that icmp_error() touches only ifp->if_mtu.
				 */
				/*XXX*/
				destifp = NULL;
				if (sp->req != NULL
				 && sp->req->sav != NULL
				 && sp->req->sav->sah != NULL) {
					ro = &sp->req->sav->sah->sa_route;
					if (ro->ro_rt && ro->ro_rt->rt_ifp) {
						dummyifp.if_mtu =
						    ro->ro_rt->rt_ifp->if_mtu;
						dummyifp.if_mtu -= ipsechdr;
						destifp = &dummyifp;
					}
				}

				key_freesp(sp);
			}
		}
#endif /*IPSEC*/
		ipstat.ips_cantfrag++;
		break;

	case ENOBUFS:
		type = ICMP_SOURCEQUENCH;
		code = 0;
		break;
	}
	icmp_error(mcopy, type, code, dest, destifp);
}

void
ip_savecontrol(inp, mp, ip, m)
	register struct inpcb *inp;
	register struct mbuf **mp;
	register struct ip *ip;
	register struct mbuf *m;
{

	if (inp->inp_socket->so_options & SO_TIMESTAMP) {
		struct timeval tv;

		microtime(&tv);
		*mp = sbcreatecontrol((caddr_t) &tv, sizeof(tv),
		    SCM_TIMESTAMP, SOL_SOCKET);
		if (*mp)
			mp = &(*mp)->m_next;
	}
	if (inp->inp_flags & INP_RECVDSTADDR) {
		*mp = sbcreatecontrol((caddr_t) &ip->ip_dst,
		    sizeof(struct in_addr), IP_RECVDSTADDR, IPPROTO_IP);
		if (*mp)
			mp = &(*mp)->m_next;
	}
#ifdef notyet
	/*
	 * XXX
	 * Moving these out of udp_input() made them even more broken
	 * than they already were.
	 *	- fenner@parc.xerox.com
	 */
	/* options were tossed already */
	if (inp->inp_flags & INP_RECVOPTS) {
		*mp = sbcreatecontrol((caddr_t) opts_deleted_above,
		    sizeof(struct in_addr), IP_RECVOPTS, IPPROTO_IP);
		if (*mp)
			mp = &(*mp)->m_next;
	}
	/* ip_srcroute doesn't do what we want here, need to fix */
	if (inp->inp_flags & INP_RECVRETOPTS) {
		*mp = sbcreatecontrol((caddr_t) ip_srcroute(),
		    sizeof(struct in_addr), IP_RECVRETOPTS, IPPROTO_IP);
		if (*mp)
			mp = &(*mp)->m_next;
	}
#endif
	if (inp->inp_flags & INP_RECVIF) {
		struct sockaddr_dl sdl;

		sdl.sdl_len = offsetof(struct sockaddr_dl, sdl_data[0]);
		sdl.sdl_family = AF_LINK;
		sdl.sdl_index = m->m_pkthdr.rcvif ?
		    m->m_pkthdr.rcvif->if_index : 0;
		sdl.sdl_nlen = sdl.sdl_alen = sdl.sdl_slen = 0;
		*mp = sbcreatecontrol((caddr_t) &sdl, sdl.sdl_len,
		    IP_RECVIF, IPPROTO_IP);
		if (*mp)
			mp = &(*mp)->m_next;
	}
}

int
ip_sysctl(name, namelen, oldp, oldlenp, newp, newlen)
	int *name;
	u_int namelen;
	void *oldp;
	size_t *oldlenp;
	void *newp;
	size_t newlen;
{
	extern int subnetsarelocal;

	int error, old;

	/* All sysctl names at this level are terminal. */
	if (namelen != 1)
		return (ENOTDIR);

	switch (name[0]) {
	case IPCTL_FORWARDING:
		return (sysctl_int(oldp, oldlenp, newp, newlen, &ipforwarding));
	case IPCTL_SENDREDIRECTS:
		return (sysctl_int(oldp, oldlenp, newp, newlen,
			&ipsendredirects));
	case IPCTL_DEFTTL:
		return (sysctl_int(oldp, oldlenp, newp, newlen, &ip_defttl));
#ifdef notyet
	case IPCTL_DEFMTU:
		return (sysctl_int(oldp, oldlenp, newp, newlen, &ip_mtu));
#endif
	case IPCTL_FORWSRCRT:
		/* Don't allow this to change in a secure environment.  */
		if (securelevel > 0)
			return (sysctl_rdint(oldp, oldlenp, newp,
			    ip_forwsrcrt));
		else
			return (sysctl_int(oldp, oldlenp, newp, newlen,
			    &ip_forwsrcrt));
	case IPCTL_DIRECTEDBCAST:
		return (sysctl_int(oldp, oldlenp, newp, newlen,
		    &ip_directedbcast));
	case IPCTL_ALLOWSRCRT:
		return (sysctl_int(oldp, oldlenp, newp, newlen,
		    &ip_allowsrcrt));
	case IPCTL_SUBNETSARELOCAL:
		return (sysctl_int(oldp, oldlenp, newp, newlen,
		    &subnetsarelocal));
	case IPCTL_MTUDISC:
		error = sysctl_int(oldp, oldlenp, newp, newlen,
		    &ip_mtudisc);
		if (ip_mtudisc != 0 && ip_mtudisc_timeout_q == NULL) {
			ip_mtudisc_timeout_q = 
			    rt_timer_queue_create(ip_mtudisc_timeout);
		} else if (ip_mtudisc == 0 && ip_mtudisc_timeout_q != NULL) {
			rt_timer_queue_destroy(ip_mtudisc_timeout_q, TRUE);
			ip_mtudisc_timeout_q = NULL;
		}
		return error;
	case IPCTL_ANONPORTMIN:
		old = anonportmin;
		error = sysctl_int(oldp, oldlenp, newp, newlen, &anonportmin);
		if (anonportmin >= anonportmax || anonportmin > 65535
#ifndef IPNOPRIVPORTS
		    || anonportmin < IPPORT_RESERVED
#endif
		    ) {
			anonportmin = old;
			return (EINVAL);
		}
		return (error);
	case IPCTL_ANONPORTMAX:
		old = anonportmax;
		error = sysctl_int(oldp, oldlenp, newp, newlen, &anonportmax);
		if (anonportmin >= anonportmax || anonportmax > 65535
#ifndef IPNOPRIVPORTS
		    || anonportmax < IPPORT_RESERVED
#endif
		    ) {
			anonportmax = old;
			return (EINVAL);
		}
		return (error);
	case IPCTL_MTUDISCTIMEOUT:
		error = sysctl_int(oldp, oldlenp, newp, newlen,
		   &ip_mtudisc_timeout);
		if (ip_mtudisc_timeout_q != NULL)
			rt_timer_queue_change(ip_mtudisc_timeout_q, 
					      ip_mtudisc_timeout);
		return (error);
#ifdef GATEWAY
	case IPCTL_MAXFLOWS:
	    {
		int s;

		error = sysctl_int(oldp, oldlenp, newp, newlen,
		   &ip_maxflows);
		s = splsoftnet();
		ipflow_reap(0);
		splx(s);
		return (error);
	    }
#endif
#if NGIF > 0
	case IPCTL_GIF_TTL:
		return(sysctl_int(oldp, oldlenp, newp, newlen,
				  &ip_gif_ttl));
#endif
	default:
		return (EOPNOTSUPP);
	}
	/* NOTREACHED */
}