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ip_input.c revision 1.166
      1 /*	$NetBSD: ip_input.c,v 1.166 2003/06/15 02:49:33 matt Exp $	*/
      2 
      3 /*
      4  * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
      5  * All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  * 3. Neither the name of the project nor the names of its contributors
     16  *    may be used to endorse or promote products derived from this software
     17  *    without specific prior written permission.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
     20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
     23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     29  * SUCH DAMAGE.
     30  */
     31 
     32 /*-
     33  * Copyright (c) 1998 The NetBSD Foundation, Inc.
     34  * All rights reserved.
     35  *
     36  * This code is derived from software contributed to The NetBSD Foundation
     37  * by Public Access Networks Corporation ("Panix").  It was developed under
     38  * contract to Panix by Eric Haszlakiewicz and Thor Lancelot Simon.
     39  *
     40  * Redistribution and use in source and binary forms, with or without
     41  * modification, are permitted provided that the following conditions
     42  * are met:
     43  * 1. Redistributions of source code must retain the above copyright
     44  *    notice, this list of conditions and the following disclaimer.
     45  * 2. Redistributions in binary form must reproduce the above copyright
     46  *    notice, this list of conditions and the following disclaimer in the
     47  *    documentation and/or other materials provided with the distribution.
     48  * 3. All advertising materials mentioning features or use of this software
     49  *    must display the following acknowledgement:
     50  *	This product includes software developed by the NetBSD
     51  *	Foundation, Inc. and its contributors.
     52  * 4. Neither the name of The NetBSD Foundation nor the names of its
     53  *    contributors may be used to endorse or promote products derived
     54  *    from this software without specific prior written permission.
     55  *
     56  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     57  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     58  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     59  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     60  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     61  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     62  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     63  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     64  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     65  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     66  * POSSIBILITY OF SUCH DAMAGE.
     67  */
     68 
     69 /*
     70  * Copyright (c) 1982, 1986, 1988, 1993
     71  *	The Regents of the University of California.  All rights reserved.
     72  *
     73  * Redistribution and use in source and binary forms, with or without
     74  * modification, are permitted provided that the following conditions
     75  * are met:
     76  * 1. Redistributions of source code must retain the above copyright
     77  *    notice, this list of conditions and the following disclaimer.
     78  * 2. Redistributions in binary form must reproduce the above copyright
     79  *    notice, this list of conditions and the following disclaimer in the
     80  *    documentation and/or other materials provided with the distribution.
     81  * 3. All advertising materials mentioning features or use of this software
     82  *    must display the following acknowledgement:
     83  *	This product includes software developed by the University of
     84  *	California, Berkeley and its contributors.
     85  * 4. Neither the name of the University nor the names of its contributors
     86  *    may be used to endorse or promote products derived from this software
     87  *    without specific prior written permission.
     88  *
     89  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     90  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     91  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     92  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     93  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     94  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     95  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     96  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     97  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     98  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     99  * SUCH DAMAGE.
    100  *
    101  *	@(#)ip_input.c	8.2 (Berkeley) 1/4/94
    102  */
    103 
    104 #include <sys/cdefs.h>
    105 __KERNEL_RCSID(0, "$NetBSD: ip_input.c,v 1.166 2003/06/15 02:49:33 matt Exp $");
    106 
    107 #include "opt_gateway.h"
    108 #include "opt_pfil_hooks.h"
    109 #include "opt_ipsec.h"
    110 #include "opt_mrouting.h"
    111 #include "opt_inet_csum.h"
    112 
    113 #include <sys/param.h>
    114 #include <sys/systm.h>
    115 #include <sys/malloc.h>
    116 #include <sys/mbuf.h>
    117 #include <sys/domain.h>
    118 #include <sys/protosw.h>
    119 #include <sys/socket.h>
    120 #include <sys/socketvar.h>
    121 #include <sys/errno.h>
    122 #include <sys/time.h>
    123 #include <sys/kernel.h>
    124 #include <sys/pool.h>
    125 #include <sys/sysctl.h>
    126 
    127 #include <net/if.h>
    128 #include <net/if_dl.h>
    129 #include <net/route.h>
    130 #include <net/pfil.h>
    131 
    132 #include <netinet/in.h>
    133 #include <netinet/in_systm.h>
    134 #include <netinet/ip.h>
    135 #include <netinet/in_pcb.h>
    136 #include <netinet/in_var.h>
    137 #include <netinet/ip_var.h>
    138 #include <netinet/ip_icmp.h>
    139 /* just for gif_ttl */
    140 #include <netinet/in_gif.h>
    141 #include "gif.h"
    142 #include <net/if_gre.h>
    143 #include "gre.h"
    144 
    145 #ifdef MROUTING
    146 #include <netinet/ip_mroute.h>
    147 #endif
    148 
    149 #ifdef IPSEC
    150 #include <netinet6/ipsec.h>
    151 #include <netkey/key.h>
    152 #endif
    153 
    154 #ifndef	IPFORWARDING
    155 #ifdef GATEWAY
    156 #define	IPFORWARDING	1	/* forward IP packets not for us */
    157 #else /* GATEWAY */
    158 #define	IPFORWARDING	0	/* don't forward IP packets not for us */
    159 #endif /* GATEWAY */
    160 #endif /* IPFORWARDING */
    161 #ifndef	IPSENDREDIRECTS
    162 #define	IPSENDREDIRECTS	1
    163 #endif
    164 #ifndef IPFORWSRCRT
    165 #define	IPFORWSRCRT	1	/* forward source-routed packets */
    166 #endif
    167 #ifndef IPALLOWSRCRT
    168 #define	IPALLOWSRCRT	1	/* allow source-routed packets */
    169 #endif
    170 #ifndef IPMTUDISC
    171 #define IPMTUDISC	1
    172 #endif
    173 #ifndef IPMTUDISCTIMEOUT
    174 #define IPMTUDISCTIMEOUT (10 * 60)	/* as per RFC 1191 */
    175 #endif
    176 
    177 /*
    178  * Note: DIRECTED_BROADCAST is handled this way so that previous
    179  * configuration using this option will Just Work.
    180  */
    181 #ifndef IPDIRECTEDBCAST
    182 #ifdef DIRECTED_BROADCAST
    183 #define IPDIRECTEDBCAST	1
    184 #else
    185 #define	IPDIRECTEDBCAST	0
    186 #endif /* DIRECTED_BROADCAST */
    187 #endif /* IPDIRECTEDBCAST */
    188 int	ipforwarding = IPFORWARDING;
    189 int	ipsendredirects = IPSENDREDIRECTS;
    190 int	ip_defttl = IPDEFTTL;
    191 int	ip_forwsrcrt = IPFORWSRCRT;
    192 int	ip_directedbcast = IPDIRECTEDBCAST;
    193 int	ip_allowsrcrt = IPALLOWSRCRT;
    194 int	ip_mtudisc = IPMTUDISC;
    195 int	ip_mtudisc_timeout = IPMTUDISCTIMEOUT;
    196 #ifdef DIAGNOSTIC
    197 int	ipprintfs = 0;
    198 #endif
    199 /*
    200  * XXX - Setting ip_checkinterface mostly implements the receive side of
    201  * the Strong ES model described in RFC 1122, but since the routing table
    202  * and transmit implementation do not implement the Strong ES model,
    203  * setting this to 1 results in an odd hybrid.
    204  *
    205  * XXX - ip_checkinterface currently must be disabled if you use ipnat
    206  * to translate the destination address to another local interface.
    207  *
    208  * XXX - ip_checkinterface must be disabled if you add IP aliases
    209  * to the loopback interface instead of the interface where the
    210  * packets for those addresses are received.
    211  */
    212 int	ip_checkinterface = 0;
    213 
    214 
    215 struct rttimer_queue *ip_mtudisc_timeout_q = NULL;
    216 
    217 extern	struct domain inetdomain;
    218 int	ipqmaxlen = IFQ_MAXLEN;
    219 u_long	in_ifaddrhash;				/* size of hash table - 1 */
    220 int	in_ifaddrentries;			/* total number of addrs */
    221 struct	in_ifaddrhead in_ifaddr;
    222 struct	in_ifaddrhashhead *in_ifaddrhashtbl;
    223 u_long	in_multihash;				/* size of hash table - 1 */
    224 int	in_multientries;			/* total number of addrs */
    225 struct	in_multihead in_multi;
    226 struct	in_multihashhead *in_multihashtbl;
    227 struct	ifqueue ipintrq;
    228 struct	ipstat	ipstat;
    229 u_int16_t	ip_id;
    230 
    231 #ifdef PFIL_HOOKS
    232 struct pfil_head inet_pfil_hook;
    233 #endif
    234 
    235 struct ipqhead ipq;
    236 int	ipq_locked;
    237 int	ip_nfragpackets = 0;
    238 int	ip_maxfragpackets = 200;
    239 
    240 static __inline int ipq_lock_try __P((void));
    241 static __inline void ipq_unlock __P((void));
    242 
    243 static __inline int
    244 ipq_lock_try()
    245 {
    246 	int s;
    247 
    248 	/*
    249 	 * Use splvm() -- we're blocking things that would cause
    250 	 * mbuf allocation.
    251 	 */
    252 	s = splvm();
    253 	if (ipq_locked) {
    254 		splx(s);
    255 		return (0);
    256 	}
    257 	ipq_locked = 1;
    258 	splx(s);
    259 	return (1);
    260 }
    261 
    262 static __inline void
    263 ipq_unlock()
    264 {
    265 	int s;
    266 
    267 	s = splvm();
    268 	ipq_locked = 0;
    269 	splx(s);
    270 }
    271 
    272 #ifdef DIAGNOSTIC
    273 #define	IPQ_LOCK()							\
    274 do {									\
    275 	if (ipq_lock_try() == 0) {					\
    276 		printf("%s:%d: ipq already locked\n", __FILE__, __LINE__); \
    277 		panic("ipq_lock");					\
    278 	}								\
    279 } while (/*CONSTCOND*/ 0)
    280 #define	IPQ_LOCK_CHECK()						\
    281 do {									\
    282 	if (ipq_locked == 0) {						\
    283 		printf("%s:%d: ipq lock not held\n", __FILE__, __LINE__); \
    284 		panic("ipq lock check");				\
    285 	}								\
    286 } while (/*CONSTCOND*/ 0)
    287 #else
    288 #define	IPQ_LOCK()		(void) ipq_lock_try()
    289 #define	IPQ_LOCK_CHECK()	/* nothing */
    290 #endif
    291 
    292 #define	IPQ_UNLOCK()		ipq_unlock()
    293 
    294 struct pool inmulti_pool;
    295 struct pool ipqent_pool;
    296 
    297 #ifdef INET_CSUM_COUNTERS
    298 #include <sys/device.h>
    299 
    300 struct evcnt ip_hwcsum_bad = EVCNT_INITIALIZER(EVCNT_TYPE_MISC,
    301     NULL, "inet", "hwcsum bad");
    302 struct evcnt ip_hwcsum_ok = EVCNT_INITIALIZER(EVCNT_TYPE_MISC,
    303     NULL, "inet", "hwcsum ok");
    304 struct evcnt ip_swcsum = EVCNT_INITIALIZER(EVCNT_TYPE_MISC,
    305     NULL, "inet", "swcsum");
    306 
    307 #define	INET_CSUM_COUNTER_INCR(ev)	(ev)->ev_count++
    308 
    309 #else
    310 
    311 #define	INET_CSUM_COUNTER_INCR(ev)	/* nothing */
    312 
    313 #endif /* INET_CSUM_COUNTERS */
    314 
    315 /*
    316  * We need to save the IP options in case a protocol wants to respond
    317  * to an incoming packet over the same route if the packet got here
    318  * using IP source routing.  This allows connection establishment and
    319  * maintenance when the remote end is on a network that is not known
    320  * to us.
    321  */
    322 int	ip_nhops = 0;
    323 static	struct ip_srcrt {
    324 	struct	in_addr dst;			/* final destination */
    325 	char	nop;				/* one NOP to align */
    326 	char	srcopt[IPOPT_OFFSET + 1];	/* OPTVAL, OLEN and OFFSET */
    327 	struct	in_addr route[MAX_IPOPTLEN/sizeof(struct in_addr)];
    328 } ip_srcrt;
    329 
    330 static void save_rte __P((u_char *, struct in_addr));
    331 
    332 #ifdef MBUFTRACE
    333 struct mowner ip_rx_mowner = { "internet", "rx" };
    334 struct mowner ip_tx_mowner = { "internet", "tx" };
    335 #endif
    336 
    337 /*
    338  * IP initialization: fill in IP protocol switch table.
    339  * All protocols not implemented in kernel go to raw IP protocol handler.
    340  */
    341 void
    342 ip_init()
    343 {
    344 	struct protosw *pr;
    345 	int i;
    346 
    347 	pool_init(&inmulti_pool, sizeof(struct in_multi), 0, 0, 0, "inmltpl",
    348 	    NULL);
    349 	pool_init(&ipqent_pool, sizeof(struct ipqent), 0, 0, 0, "ipqepl",
    350 	    NULL);
    351 
    352 	pr = pffindproto(PF_INET, IPPROTO_RAW, SOCK_RAW);
    353 	if (pr == 0)
    354 		panic("ip_init");
    355 	for (i = 0; i < IPPROTO_MAX; i++)
    356 		ip_protox[i] = pr - inetsw;
    357 	for (pr = inetdomain.dom_protosw;
    358 	    pr < inetdomain.dom_protoswNPROTOSW; pr++)
    359 		if (pr->pr_domain->dom_family == PF_INET &&
    360 		    pr->pr_protocol && pr->pr_protocol != IPPROTO_RAW)
    361 			ip_protox[pr->pr_protocol] = pr - inetsw;
    362 	LIST_INIT(&ipq);
    363 	ip_id = time.tv_sec & 0xffff;
    364 	ipintrq.ifq_maxlen = ipqmaxlen;
    365 	TAILQ_INIT(&in_ifaddr);
    366 	in_ifaddrhashtbl = hashinit(IN_IFADDR_HASH_SIZE, HASH_LIST, M_IFADDR,
    367 	    M_WAITOK, &in_ifaddrhash);
    368 	in_multihashtbl = hashinit(IN_IFADDR_HASH_SIZE, HASH_LIST, M_IPMADDR,
    369 	    M_WAITOK, &in_multihash);
    370 	ip_mtudisc_timeout_q = rt_timer_queue_create(ip_mtudisc_timeout);
    371 #ifdef GATEWAY
    372 	ipflow_init();
    373 #endif
    374 
    375 #ifdef PFIL_HOOKS
    376 	/* Register our Packet Filter hook. */
    377 	inet_pfil_hook.ph_type = PFIL_TYPE_AF;
    378 	inet_pfil_hook.ph_af   = AF_INET;
    379 	i = pfil_head_register(&inet_pfil_hook);
    380 	if (i != 0)
    381 		printf("ip_init: WARNING: unable to register pfil hook, "
    382 		    "error %d\n", i);
    383 #endif /* PFIL_HOOKS */
    384 
    385 #ifdef INET_CSUM_COUNTERS
    386 	evcnt_attach_static(&ip_hwcsum_bad);
    387 	evcnt_attach_static(&ip_hwcsum_ok);
    388 	evcnt_attach_static(&ip_swcsum);
    389 #endif /* INET_CSUM_COUNTERS */
    390 
    391 #ifdef MBUFTRACE
    392 	MOWNER_ATTACH(&ip_tx_mowner);
    393 	MOWNER_ATTACH(&ip_rx_mowner);
    394 #endif /* MBUFTRACE */
    395 }
    396 
    397 struct	sockaddr_in ipaddr = { sizeof(ipaddr), AF_INET };
    398 struct	route ipforward_rt;
    399 
    400 /*
    401  * IP software interrupt routine
    402  */
    403 void
    404 ipintr()
    405 {
    406 	int s;
    407 	struct mbuf *m;
    408 
    409 	while (1) {
    410 		s = splnet();
    411 		IF_DEQUEUE(&ipintrq, m);
    412 		splx(s);
    413 		if (m == 0)
    414 			return;
    415 		MCLAIM(m, &ip_rx_mowner);
    416 		ip_input(m);
    417 	}
    418 }
    419 
    420 /*
    421  * Ip input routine.  Checksum and byte swap header.  If fragmented
    422  * try to reassemble.  Process options.  Pass to next level.
    423  */
    424 void
    425 ip_input(struct mbuf *m)
    426 {
    427 	struct ip *ip = NULL;
    428 	struct ipq *fp;
    429 	struct in_ifaddr *ia;
    430 	struct ifaddr *ifa;
    431 	struct ipqent *ipqe;
    432 	int hlen = 0, mff, len;
    433 	int downmatch;
    434 	int checkif;
    435 
    436 	MCLAIM(m, &ip_rx_mowner);
    437 #ifdef	DIAGNOSTIC
    438 	if ((m->m_flags & M_PKTHDR) == 0)
    439 		panic("ipintr no HDR");
    440 #endif
    441 #ifdef IPSEC
    442 	/*
    443 	 * should the inner packet be considered authentic?
    444 	 * see comment in ah4_input().
    445 	 */
    446 	if (m) {
    447 		m->m_flags &= ~M_AUTHIPHDR;
    448 		m->m_flags &= ~M_AUTHIPDGM;
    449 	}
    450 #endif
    451 
    452 	/*
    453 	 * If no IP addresses have been set yet but the interfaces
    454 	 * are receiving, can't do anything with incoming packets yet.
    455 	 */
    456 	if (TAILQ_FIRST(&in_ifaddr) == 0)
    457 		goto bad;
    458 	ipstat.ips_total++;
    459 	/*
    460 	 * If the IP header is not aligned, slurp it up into a new
    461 	 * mbuf with space for link headers, in the event we forward
    462 	 * it.  Otherwise, if it is aligned, make sure the entire
    463 	 * base IP header is in the first mbuf of the chain.
    464 	 */
    465 	if (IP_HDR_ALIGNED_P(mtod(m, caddr_t)) == 0) {
    466 		if ((m = m_copyup(m, sizeof(struct ip),
    467 				  (max_linkhdr + 3) & ~3)) == NULL) {
    468 			/* XXXJRT new stat, please */
    469 			ipstat.ips_toosmall++;
    470 			return;
    471 		}
    472 	} else if (__predict_false(m->m_len < sizeof (struct ip))) {
    473 		if ((m = m_pullup(m, sizeof (struct ip))) == NULL) {
    474 			ipstat.ips_toosmall++;
    475 			return;
    476 		}
    477 	}
    478 	ip = mtod(m, struct ip *);
    479 	if (ip->ip_v != IPVERSION) {
    480 		ipstat.ips_badvers++;
    481 		goto bad;
    482 	}
    483 	hlen = ip->ip_hl << 2;
    484 	if (hlen < sizeof(struct ip)) {	/* minimum header length */
    485 		ipstat.ips_badhlen++;
    486 		goto bad;
    487 	}
    488 	if (hlen > m->m_len) {
    489 		if ((m = m_pullup(m, hlen)) == 0) {
    490 			ipstat.ips_badhlen++;
    491 			return;
    492 		}
    493 		ip = mtod(m, struct ip *);
    494 	}
    495 
    496 	/*
    497 	 * RFC1122: packets with a multicast source address are
    498 	 * not allowed.
    499 	 */
    500 	if (IN_MULTICAST(ip->ip_src.s_addr)) {
    501 		ipstat.ips_badaddr++;
    502 		goto bad;
    503 	}
    504 
    505 	/* 127/8 must not appear on wire - RFC1122 */
    506 	if ((ntohl(ip->ip_dst.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET ||
    507 	    (ntohl(ip->ip_src.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET) {
    508 		if ((m->m_pkthdr.rcvif->if_flags & IFF_LOOPBACK) == 0) {
    509 			ipstat.ips_badaddr++;
    510 			goto bad;
    511 		}
    512 	}
    513 
    514 	switch (m->m_pkthdr.csum_flags &
    515 		((m->m_pkthdr.rcvif->if_csum_flags_rx & M_CSUM_IPv4) |
    516 		 M_CSUM_IPv4_BAD)) {
    517 	case M_CSUM_IPv4|M_CSUM_IPv4_BAD:
    518 		INET_CSUM_COUNTER_INCR(&ip_hwcsum_bad);
    519 		goto badcsum;
    520 
    521 	case M_CSUM_IPv4:
    522 		/* Checksum was okay. */
    523 		INET_CSUM_COUNTER_INCR(&ip_hwcsum_ok);
    524 		break;
    525 
    526 	default:
    527 		/* Must compute it ourselves. */
    528 		INET_CSUM_COUNTER_INCR(&ip_swcsum);
    529 		if (in_cksum(m, hlen) != 0)
    530 			goto bad;
    531 		break;
    532 	}
    533 
    534 	/* Retrieve the packet length. */
    535 	len = ntohs(ip->ip_len);
    536 
    537 	/*
    538 	 * Check for additional length bogosity
    539 	 */
    540 	if (len < hlen) {
    541 	 	ipstat.ips_badlen++;
    542 		goto bad;
    543 	}
    544 
    545 	/*
    546 	 * Check that the amount of data in the buffers
    547 	 * is as at least much as the IP header would have us expect.
    548 	 * Trim mbufs if longer than we expect.
    549 	 * Drop packet if shorter than we expect.
    550 	 */
    551 	if (m->m_pkthdr.len < len) {
    552 		ipstat.ips_tooshort++;
    553 		goto bad;
    554 	}
    555 	if (m->m_pkthdr.len > len) {
    556 		if (m->m_len == m->m_pkthdr.len) {
    557 			m->m_len = len;
    558 			m->m_pkthdr.len = len;
    559 		} else
    560 			m_adj(m, len - m->m_pkthdr.len);
    561 	}
    562 
    563 #ifdef IPSEC
    564 	/* ipflow (IP fast forwarding) is not compatible with IPsec. */
    565 	m->m_flags &= ~M_CANFASTFWD;
    566 #else
    567 	/*
    568 	 * Assume that we can create a fast-forward IP flow entry
    569 	 * based on this packet.
    570 	 */
    571 	m->m_flags |= M_CANFASTFWD;
    572 #endif
    573 
    574 #ifdef PFIL_HOOKS
    575 	/*
    576 	 * Run through list of hooks for input packets.  If there are any
    577 	 * filters which require that additional packets in the flow are
    578 	 * not fast-forwarded, they must clear the M_CANFASTFWD flag.
    579 	 * Note that filters must _never_ set this flag, as another filter
    580 	 * in the list may have previously cleared it.
    581 	 */
    582 	/*
    583 	 * let ipfilter look at packet on the wire,
    584 	 * not the decapsulated packet.
    585 	 */
    586 #ifdef IPSEC
    587 	if (!ipsec_getnhist(m))
    588 #else
    589 	if (1)
    590 #endif
    591 	{
    592 		if (pfil_run_hooks(&inet_pfil_hook, &m, m->m_pkthdr.rcvif,
    593 				   PFIL_IN) != 0)
    594 		return;
    595 		if (m == NULL)
    596 			return;
    597 		ip = mtod(m, struct ip *);
    598 		hlen = ip->ip_hl << 2;
    599 	}
    600 #endif /* PFIL_HOOKS */
    601 
    602 #ifdef ALTQ
    603 	/* XXX Temporary until ALTQ is changed to use a pfil hook */
    604 	if (altq_input != NULL && (*altq_input)(m, AF_INET) == 0) {
    605 		/* packet dropped by traffic conditioner */
    606 		return;
    607 	}
    608 #endif
    609 
    610 	/*
    611 	 * Process options and, if not destined for us,
    612 	 * ship it on.  ip_dooptions returns 1 when an
    613 	 * error was detected (causing an icmp message
    614 	 * to be sent and the original packet to be freed).
    615 	 */
    616 	ip_nhops = 0;		/* for source routed packets */
    617 	if (hlen > sizeof (struct ip) && ip_dooptions(m))
    618 		return;
    619 
    620 	/*
    621 	 * Enable a consistency check between the destination address
    622 	 * and the arrival interface for a unicast packet (the RFC 1122
    623 	 * strong ES model) if IP forwarding is disabled and the packet
    624 	 * is not locally generated.
    625 	 *
    626 	 * XXX - Checking also should be disabled if the destination
    627 	 * address is ipnat'ed to a different interface.
    628 	 *
    629 	 * XXX - Checking is incompatible with IP aliases added
    630 	 * to the loopback interface instead of the interface where
    631 	 * the packets are received.
    632 	 *
    633 	 * XXX - We need to add a per ifaddr flag for this so that
    634 	 * we get finer grain control.
    635 	 */
    636 	checkif = ip_checkinterface && (ipforwarding == 0) &&
    637 	    (m->m_pkthdr.rcvif != NULL) &&
    638 	    ((m->m_pkthdr.rcvif->if_flags & IFF_LOOPBACK) == 0);
    639 
    640 	/*
    641 	 * Check our list of addresses, to see if the packet is for us.
    642 	 *
    643 	 * Traditional 4.4BSD did not consult IFF_UP at all.
    644 	 * The behavior here is to treat addresses on !IFF_UP interface
    645 	 * as not mine.
    646 	 */
    647 	downmatch = 0;
    648 	LIST_FOREACH(ia, &IN_IFADDR_HASH(ip->ip_dst.s_addr), ia_hash) {
    649 		if (in_hosteq(ia->ia_addr.sin_addr, ip->ip_dst)) {
    650 			if (checkif && ia->ia_ifp != m->m_pkthdr.rcvif)
    651 				continue;
    652 			if ((ia->ia_ifp->if_flags & IFF_UP) != 0)
    653 				break;
    654 			else
    655 				downmatch++;
    656 		}
    657 	}
    658 	if (ia != NULL)
    659 		goto ours;
    660 	if (m->m_pkthdr.rcvif->if_flags & IFF_BROADCAST) {
    661 		TAILQ_FOREACH(ifa, &m->m_pkthdr.rcvif->if_addrlist, ifa_list) {
    662 			if (ifa->ifa_addr->sa_family != AF_INET)
    663 				continue;
    664 			ia = ifatoia(ifa);
    665 			if (in_hosteq(ip->ip_dst, ia->ia_broadaddr.sin_addr) ||
    666 			    in_hosteq(ip->ip_dst, ia->ia_netbroadcast) ||
    667 			    /*
    668 			     * Look for all-0's host part (old broadcast addr),
    669 			     * either for subnet or net.
    670 			     */
    671 			    ip->ip_dst.s_addr == ia->ia_subnet ||
    672 			    ip->ip_dst.s_addr == ia->ia_net)
    673 				goto ours;
    674 			/*
    675 			 * An interface with IP address zero accepts
    676 			 * all packets that arrive on that interface.
    677 			 */
    678 			if (in_nullhost(ia->ia_addr.sin_addr))
    679 				goto ours;
    680 		}
    681 	}
    682 	if (IN_MULTICAST(ip->ip_dst.s_addr)) {
    683 		struct in_multi *inm;
    684 #ifdef MROUTING
    685 		extern struct socket *ip_mrouter;
    686 
    687 		if (M_READONLY(m)) {
    688 			if ((m = m_pullup(m, hlen)) == 0) {
    689 				ipstat.ips_toosmall++;
    690 				return;
    691 			}
    692 			ip = mtod(m, struct ip *);
    693 		}
    694 
    695 		if (ip_mrouter) {
    696 			/*
    697 			 * If we are acting as a multicast router, all
    698 			 * incoming multicast packets are passed to the
    699 			 * kernel-level multicast forwarding function.
    700 			 * The packet is returned (relatively) intact; if
    701 			 * ip_mforward() returns a non-zero value, the packet
    702 			 * must be discarded, else it may be accepted below.
    703 			 *
    704 			 * (The IP ident field is put in the same byte order
    705 			 * as expected when ip_mforward() is called from
    706 			 * ip_output().)
    707 			 */
    708 			if (ip_mforward(m, m->m_pkthdr.rcvif) != 0) {
    709 				ipstat.ips_cantforward++;
    710 				m_freem(m);
    711 				return;
    712 			}
    713 
    714 			/*
    715 			 * The process-level routing demon needs to receive
    716 			 * all multicast IGMP packets, whether or not this
    717 			 * host belongs to their destination groups.
    718 			 */
    719 			if (ip->ip_p == IPPROTO_IGMP)
    720 				goto ours;
    721 			ipstat.ips_forward++;
    722 		}
    723 #endif
    724 		/*
    725 		 * See if we belong to the destination multicast group on the
    726 		 * arrival interface.
    727 		 */
    728 		IN_LOOKUP_MULTI(ip->ip_dst, m->m_pkthdr.rcvif, inm);
    729 		if (inm == NULL) {
    730 			ipstat.ips_cantforward++;
    731 			m_freem(m);
    732 			return;
    733 		}
    734 		goto ours;
    735 	}
    736 	if (ip->ip_dst.s_addr == INADDR_BROADCAST ||
    737 	    in_nullhost(ip->ip_dst))
    738 		goto ours;
    739 
    740 	/*
    741 	 * Not for us; forward if possible and desirable.
    742 	 */
    743 	if (ipforwarding == 0) {
    744 		ipstat.ips_cantforward++;
    745 		m_freem(m);
    746 	} else {
    747 		/*
    748 		 * If ip_dst matched any of my address on !IFF_UP interface,
    749 		 * and there's no IFF_UP interface that matches ip_dst,
    750 		 * send icmp unreach.  Forwarding it will result in in-kernel
    751 		 * forwarding loop till TTL goes to 0.
    752 		 */
    753 		if (downmatch) {
    754 			icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, 0, 0);
    755 			ipstat.ips_cantforward++;
    756 			return;
    757 		}
    758 #ifdef IPSEC
    759 		if (ipsec4_in_reject(m, NULL)) {
    760 			ipsecstat.in_polvio++;
    761 			goto bad;
    762 		}
    763 #endif
    764 
    765 		ip_forward(m, 0);
    766 	}
    767 	return;
    768 
    769 ours:
    770 	/*
    771 	 * If offset or IP_MF are set, must reassemble.
    772 	 * Otherwise, nothing need be done.
    773 	 * (We could look in the reassembly queue to see
    774 	 * if the packet was previously fragmented,
    775 	 * but it's not worth the time; just let them time out.)
    776 	 */
    777 	if (ip->ip_off & ~htons(IP_DF|IP_RF)) {
    778 		if (M_READONLY(m)) {
    779 			if ((m = m_pullup(m, hlen)) == NULL) {
    780 				ipstat.ips_toosmall++;
    781 				goto bad;
    782 			}
    783 			ip = mtod(m, struct ip *);
    784 		}
    785 
    786 		/*
    787 		 * Look for queue of fragments
    788 		 * of this datagram.
    789 		 */
    790 		IPQ_LOCK();
    791 		LIST_FOREACH(fp, &ipq, ipq_q)
    792 			if (ip->ip_id == fp->ipq_id &&
    793 			    in_hosteq(ip->ip_src, fp->ipq_src) &&
    794 			    in_hosteq(ip->ip_dst, fp->ipq_dst) &&
    795 			    ip->ip_p == fp->ipq_p)
    796 				goto found;
    797 		fp = 0;
    798 found:
    799 
    800 		/*
    801 		 * Adjust ip_len to not reflect header,
    802 		 * set ipqe_mff if more fragments are expected,
    803 		 * convert offset of this to bytes.
    804 		 */
    805 		ip->ip_len = htons(ntohs(ip->ip_len) - hlen);
    806 		mff = (ip->ip_off & htons(IP_MF)) != 0;
    807 		if (mff) {
    808 		        /*
    809 		         * Make sure that fragments have a data length
    810 			 * that's a non-zero multiple of 8 bytes.
    811 		         */
    812 			if (ntohs(ip->ip_len) == 0 ||
    813 			    (ntohs(ip->ip_len) & 0x7) != 0) {
    814 				ipstat.ips_badfrags++;
    815 				IPQ_UNLOCK();
    816 				goto bad;
    817 			}
    818 		}
    819 		ip->ip_off = htons((ntohs(ip->ip_off) & IP_OFFMASK) << 3);
    820 
    821 		/*
    822 		 * If datagram marked as having more fragments
    823 		 * or if this is not the first fragment,
    824 		 * attempt reassembly; if it succeeds, proceed.
    825 		 */
    826 		if (mff || ip->ip_off != htons(0)) {
    827 			ipstat.ips_fragments++;
    828 			ipqe = pool_get(&ipqent_pool, PR_NOWAIT);
    829 			if (ipqe == NULL) {
    830 				ipstat.ips_rcvmemdrop++;
    831 				IPQ_UNLOCK();
    832 				goto bad;
    833 			}
    834 			ipqe->ipqe_mff = mff;
    835 			ipqe->ipqe_m = m;
    836 			ipqe->ipqe_ip = ip;
    837 			m = ip_reass(ipqe, fp);
    838 			if (m == 0) {
    839 				IPQ_UNLOCK();
    840 				return;
    841 			}
    842 			ipstat.ips_reassembled++;
    843 			ip = mtod(m, struct ip *);
    844 			hlen = ip->ip_hl << 2;
    845 			ip->ip_len = htons(ntohs(ip->ip_len) + hlen);
    846 		} else
    847 			if (fp)
    848 				ip_freef(fp);
    849 		IPQ_UNLOCK();
    850 	}
    851 
    852 #ifdef IPSEC
    853 	/*
    854 	 * enforce IPsec policy checking if we are seeing last header.
    855 	 * note that we do not visit this with protocols with pcb layer
    856 	 * code - like udp/tcp/raw ip.
    857 	 */
    858 	if ((inetsw[ip_protox[ip->ip_p]].pr_flags & PR_LASTHDR) != 0 &&
    859 	    ipsec4_in_reject(m, NULL)) {
    860 		ipsecstat.in_polvio++;
    861 		goto bad;
    862 	}
    863 #endif
    864 
    865 	/*
    866 	 * Switch out to protocol's input routine.
    867 	 */
    868 #if IFA_STATS
    869 	if (ia && ip)
    870 		ia->ia_ifa.ifa_data.ifad_inbytes += ntohs(ip->ip_len);
    871 #endif
    872 	ipstat.ips_delivered++;
    873     {
    874 	int off = hlen, nh = ip->ip_p;
    875 
    876 	(*inetsw[ip_protox[nh]].pr_input)(m, off, nh);
    877 	return;
    878     }
    879 bad:
    880 	m_freem(m);
    881 	return;
    882 
    883 badcsum:
    884 	ipstat.ips_badsum++;
    885 	m_freem(m);
    886 }
    887 
    888 /*
    889  * Take incoming datagram fragment and try to
    890  * reassemble it into whole datagram.  If a chain for
    891  * reassembly of this datagram already exists, then it
    892  * is given as fp; otherwise have to make a chain.
    893  */
    894 struct mbuf *
    895 ip_reass(ipqe, fp)
    896 	struct ipqent *ipqe;
    897 	struct ipq *fp;
    898 {
    899 	struct mbuf *m = ipqe->ipqe_m;
    900 	struct ipqent *nq, *p, *q;
    901 	struct ip *ip;
    902 	struct mbuf *t;
    903 	int hlen = ipqe->ipqe_ip->ip_hl << 2;
    904 	int i, next;
    905 
    906 	IPQ_LOCK_CHECK();
    907 
    908 	/*
    909 	 * Presence of header sizes in mbufs
    910 	 * would confuse code below.
    911 	 */
    912 	m->m_data += hlen;
    913 	m->m_len -= hlen;
    914 
    915 	/*
    916 	 * If first fragment to arrive, create a reassembly queue.
    917 	 */
    918 	if (fp == 0) {
    919 		/*
    920 		 * Enforce upper bound on number of fragmented packets
    921 		 * for which we attempt reassembly;
    922 		 * If maxfrag is 0, never accept fragments.
    923 		 * If maxfrag is -1, accept all fragments without limitation.
    924 		 */
    925 		if (ip_maxfragpackets < 0)
    926 			;
    927 		else if (ip_nfragpackets >= ip_maxfragpackets)
    928 			goto dropfrag;
    929 		ip_nfragpackets++;
    930 		MALLOC(fp, struct ipq *, sizeof (struct ipq),
    931 		    M_FTABLE, M_NOWAIT);
    932 		if (fp == NULL)
    933 			goto dropfrag;
    934 		LIST_INSERT_HEAD(&ipq, fp, ipq_q);
    935 		fp->ipq_ttl = IPFRAGTTL;
    936 		fp->ipq_p = ipqe->ipqe_ip->ip_p;
    937 		fp->ipq_id = ipqe->ipqe_ip->ip_id;
    938 		TAILQ_INIT(&fp->ipq_fragq);
    939 		fp->ipq_src = ipqe->ipqe_ip->ip_src;
    940 		fp->ipq_dst = ipqe->ipqe_ip->ip_dst;
    941 		p = NULL;
    942 		goto insert;
    943 	}
    944 
    945 	/*
    946 	 * Find a segment which begins after this one does.
    947 	 */
    948 	for (p = NULL, q = TAILQ_FIRST(&fp->ipq_fragq); q != NULL;
    949 	    p = q, q = TAILQ_NEXT(q, ipqe_q))
    950 		if (ntohs(q->ipqe_ip->ip_off) > ntohs(ipqe->ipqe_ip->ip_off))
    951 			break;
    952 
    953 	/*
    954 	 * If there is a preceding segment, it may provide some of
    955 	 * our data already.  If so, drop the data from the incoming
    956 	 * segment.  If it provides all of our data, drop us.
    957 	 */
    958 	if (p != NULL) {
    959 		i = ntohs(p->ipqe_ip->ip_off) + ntohs(p->ipqe_ip->ip_len) -
    960 		    ntohs(ipqe->ipqe_ip->ip_off);
    961 		if (i > 0) {
    962 			if (i >= ntohs(ipqe->ipqe_ip->ip_len))
    963 				goto dropfrag;
    964 			m_adj(ipqe->ipqe_m, i);
    965 			ipqe->ipqe_ip->ip_off =
    966 			    htons(ntohs(ipqe->ipqe_ip->ip_off) + i);
    967 			ipqe->ipqe_ip->ip_len =
    968 			    htons(ntohs(ipqe->ipqe_ip->ip_len) - i);
    969 		}
    970 	}
    971 
    972 	/*
    973 	 * While we overlap succeeding segments trim them or,
    974 	 * if they are completely covered, dequeue them.
    975 	 */
    976 	for (; q != NULL &&
    977 	    ntohs(ipqe->ipqe_ip->ip_off) + ntohs(ipqe->ipqe_ip->ip_len) >
    978 	    ntohs(q->ipqe_ip->ip_off); q = nq) {
    979 		i = (ntohs(ipqe->ipqe_ip->ip_off) +
    980 		    ntohs(ipqe->ipqe_ip->ip_len)) - ntohs(q->ipqe_ip->ip_off);
    981 		if (i < ntohs(q->ipqe_ip->ip_len)) {
    982 			q->ipqe_ip->ip_len =
    983 			    htons(ntohs(q->ipqe_ip->ip_len) - i);
    984 			q->ipqe_ip->ip_off =
    985 			    htons(ntohs(q->ipqe_ip->ip_off) + i);
    986 			m_adj(q->ipqe_m, i);
    987 			break;
    988 		}
    989 		nq = TAILQ_NEXT(q, ipqe_q);
    990 		m_freem(q->ipqe_m);
    991 		TAILQ_REMOVE(&fp->ipq_fragq, q, ipqe_q);
    992 		pool_put(&ipqent_pool, q);
    993 	}
    994 
    995 insert:
    996 	/*
    997 	 * Stick new segment in its place;
    998 	 * check for complete reassembly.
    999 	 */
   1000 	if (p == NULL) {
   1001 		TAILQ_INSERT_HEAD(&fp->ipq_fragq, ipqe, ipqe_q);
   1002 	} else {
   1003 		TAILQ_INSERT_AFTER(&fp->ipq_fragq, p, ipqe, ipqe_q);
   1004 	}
   1005 	next = 0;
   1006 	for (p = NULL, q = TAILQ_FIRST(&fp->ipq_fragq); q != NULL;
   1007 	    p = q, q = TAILQ_NEXT(q, ipqe_q)) {
   1008 		if (ntohs(q->ipqe_ip->ip_off) != next)
   1009 			return (0);
   1010 		next += ntohs(q->ipqe_ip->ip_len);
   1011 	}
   1012 	if (p->ipqe_mff)
   1013 		return (0);
   1014 
   1015 	/*
   1016 	 * Reassembly is complete.  Check for a bogus message size and
   1017 	 * concatenate fragments.
   1018 	 */
   1019 	q = TAILQ_FIRST(&fp->ipq_fragq);
   1020 	ip = q->ipqe_ip;
   1021 	if ((next + (ip->ip_hl << 2)) > IP_MAXPACKET) {
   1022 		ipstat.ips_toolong++;
   1023 		ip_freef(fp);
   1024 		return (0);
   1025 	}
   1026 	m = q->ipqe_m;
   1027 	t = m->m_next;
   1028 	m->m_next = 0;
   1029 	m_cat(m, t);
   1030 	nq = TAILQ_NEXT(q, ipqe_q);
   1031 	pool_put(&ipqent_pool, q);
   1032 	for (q = nq; q != NULL; q = nq) {
   1033 		t = q->ipqe_m;
   1034 		nq = TAILQ_NEXT(q, ipqe_q);
   1035 		pool_put(&ipqent_pool, q);
   1036 		m_cat(m, t);
   1037 	}
   1038 
   1039 	/*
   1040 	 * Create header for new ip packet by
   1041 	 * modifying header of first packet;
   1042 	 * dequeue and discard fragment reassembly header.
   1043 	 * Make header visible.
   1044 	 */
   1045 	ip->ip_len = htons(next);
   1046 	ip->ip_src = fp->ipq_src;
   1047 	ip->ip_dst = fp->ipq_dst;
   1048 	LIST_REMOVE(fp, ipq_q);
   1049 	FREE(fp, M_FTABLE);
   1050 	ip_nfragpackets--;
   1051 	m->m_len += (ip->ip_hl << 2);
   1052 	m->m_data -= (ip->ip_hl << 2);
   1053 	/* some debugging cruft by sklower, below, will go away soon */
   1054 	if (m->m_flags & M_PKTHDR) { /* XXX this should be done elsewhere */
   1055 		int plen = 0;
   1056 		for (t = m; t; t = t->m_next)
   1057 			plen += t->m_len;
   1058 		m->m_pkthdr.len = plen;
   1059 	}
   1060 	return (m);
   1061 
   1062 dropfrag:
   1063 	ipstat.ips_fragdropped++;
   1064 	m_freem(m);
   1065 	pool_put(&ipqent_pool, ipqe);
   1066 	return (0);
   1067 }
   1068 
   1069 /*
   1070  * Free a fragment reassembly header and all
   1071  * associated datagrams.
   1072  */
   1073 void
   1074 ip_freef(fp)
   1075 	struct ipq *fp;
   1076 {
   1077 	struct ipqent *q, *p;
   1078 
   1079 	IPQ_LOCK_CHECK();
   1080 
   1081 	for (q = TAILQ_FIRST(&fp->ipq_fragq); q != NULL; q = p) {
   1082 		p = TAILQ_NEXT(q, ipqe_q);
   1083 		m_freem(q->ipqe_m);
   1084 		TAILQ_REMOVE(&fp->ipq_fragq, q, ipqe_q);
   1085 		pool_put(&ipqent_pool, q);
   1086 	}
   1087 	LIST_REMOVE(fp, ipq_q);
   1088 	FREE(fp, M_FTABLE);
   1089 	ip_nfragpackets--;
   1090 }
   1091 
   1092 /*
   1093  * IP timer processing;
   1094  * if a timer expires on a reassembly
   1095  * queue, discard it.
   1096  */
   1097 void
   1098 ip_slowtimo()
   1099 {
   1100 	struct ipq *fp, *nfp;
   1101 	int s = splsoftnet();
   1102 
   1103 	IPQ_LOCK();
   1104 	for (fp = LIST_FIRST(&ipq); fp != NULL; fp = nfp) {
   1105 		nfp = LIST_NEXT(fp, ipq_q);
   1106 		if (--fp->ipq_ttl == 0) {
   1107 			ipstat.ips_fragtimeout++;
   1108 			ip_freef(fp);
   1109 		}
   1110 	}
   1111 	/*
   1112 	 * If we are over the maximum number of fragments
   1113 	 * (due to the limit being lowered), drain off
   1114 	 * enough to get down to the new limit.
   1115 	 */
   1116 	if (ip_maxfragpackets < 0)
   1117 		;
   1118 	else {
   1119 		while (ip_nfragpackets > ip_maxfragpackets && LIST_FIRST(&ipq))
   1120 			ip_freef(LIST_FIRST(&ipq));
   1121 	}
   1122 	IPQ_UNLOCK();
   1123 #ifdef GATEWAY
   1124 	ipflow_slowtimo();
   1125 #endif
   1126 	splx(s);
   1127 }
   1128 
   1129 /*
   1130  * Drain off all datagram fragments.
   1131  */
   1132 void
   1133 ip_drain()
   1134 {
   1135 
   1136 	/*
   1137 	 * We may be called from a device's interrupt context.  If
   1138 	 * the ipq is already busy, just bail out now.
   1139 	 */
   1140 	if (ipq_lock_try() == 0)
   1141 		return;
   1142 
   1143 	while (LIST_FIRST(&ipq) != NULL) {
   1144 		ipstat.ips_fragdropped++;
   1145 		ip_freef(LIST_FIRST(&ipq));
   1146 	}
   1147 
   1148 	IPQ_UNLOCK();
   1149 }
   1150 
   1151 /*
   1152  * Do option processing on a datagram,
   1153  * possibly discarding it if bad options are encountered,
   1154  * or forwarding it if source-routed.
   1155  * Returns 1 if packet has been forwarded/freed,
   1156  * 0 if the packet should be processed further.
   1157  */
   1158 int
   1159 ip_dooptions(m)
   1160 	struct mbuf *m;
   1161 {
   1162 	struct ip *ip = mtod(m, struct ip *);
   1163 	u_char *cp, *cp0;
   1164 	struct ip_timestamp *ipt;
   1165 	struct in_ifaddr *ia;
   1166 	int opt, optlen, cnt, off, code, type = ICMP_PARAMPROB, forward = 0;
   1167 	struct in_addr dst;
   1168 	n_time ntime;
   1169 
   1170 	dst = ip->ip_dst;
   1171 	cp = (u_char *)(ip + 1);
   1172 	cnt = (ip->ip_hl << 2) - sizeof (struct ip);
   1173 	for (; cnt > 0; cnt -= optlen, cp += optlen) {
   1174 		opt = cp[IPOPT_OPTVAL];
   1175 		if (opt == IPOPT_EOL)
   1176 			break;
   1177 		if (opt == IPOPT_NOP)
   1178 			optlen = 1;
   1179 		else {
   1180 			if (cnt < IPOPT_OLEN + sizeof(*cp)) {
   1181 				code = &cp[IPOPT_OLEN] - (u_char *)ip;
   1182 				goto bad;
   1183 			}
   1184 			optlen = cp[IPOPT_OLEN];
   1185 			if (optlen < IPOPT_OLEN + sizeof(*cp) || optlen > cnt) {
   1186 				code = &cp[IPOPT_OLEN] - (u_char *)ip;
   1187 				goto bad;
   1188 			}
   1189 		}
   1190 		switch (opt) {
   1191 
   1192 		default:
   1193 			break;
   1194 
   1195 		/*
   1196 		 * Source routing with record.
   1197 		 * Find interface with current destination address.
   1198 		 * If none on this machine then drop if strictly routed,
   1199 		 * or do nothing if loosely routed.
   1200 		 * Record interface address and bring up next address
   1201 		 * component.  If strictly routed make sure next
   1202 		 * address is on directly accessible net.
   1203 		 */
   1204 		case IPOPT_LSRR:
   1205 		case IPOPT_SSRR:
   1206 			if (ip_allowsrcrt == 0) {
   1207 				type = ICMP_UNREACH;
   1208 				code = ICMP_UNREACH_NET_PROHIB;
   1209 				goto bad;
   1210 			}
   1211 			if (optlen < IPOPT_OFFSET + sizeof(*cp)) {
   1212 				code = &cp[IPOPT_OLEN] - (u_char *)ip;
   1213 				goto bad;
   1214 			}
   1215 			if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
   1216 				code = &cp[IPOPT_OFFSET] - (u_char *)ip;
   1217 				goto bad;
   1218 			}
   1219 			ipaddr.sin_addr = ip->ip_dst;
   1220 			ia = ifatoia(ifa_ifwithaddr(sintosa(&ipaddr)));
   1221 			if (ia == 0) {
   1222 				if (opt == IPOPT_SSRR) {
   1223 					type = ICMP_UNREACH;
   1224 					code = ICMP_UNREACH_SRCFAIL;
   1225 					goto bad;
   1226 				}
   1227 				/*
   1228 				 * Loose routing, and not at next destination
   1229 				 * yet; nothing to do except forward.
   1230 				 */
   1231 				break;
   1232 			}
   1233 			off--;			/* 0 origin */
   1234 			if ((off + sizeof(struct in_addr)) > optlen) {
   1235 				/*
   1236 				 * End of source route.  Should be for us.
   1237 				 */
   1238 				save_rte(cp, ip->ip_src);
   1239 				break;
   1240 			}
   1241 			/*
   1242 			 * locate outgoing interface
   1243 			 */
   1244 			bcopy((caddr_t)(cp + off), (caddr_t)&ipaddr.sin_addr,
   1245 			    sizeof(ipaddr.sin_addr));
   1246 			if (opt == IPOPT_SSRR)
   1247 				ia = ifatoia(ifa_ifwithaddr(sintosa(&ipaddr)));
   1248 			else
   1249 				ia = ip_rtaddr(ipaddr.sin_addr);
   1250 			if (ia == 0) {
   1251 				type = ICMP_UNREACH;
   1252 				code = ICMP_UNREACH_SRCFAIL;
   1253 				goto bad;
   1254 			}
   1255 			ip->ip_dst = ipaddr.sin_addr;
   1256 			bcopy((caddr_t)&ia->ia_addr.sin_addr,
   1257 			    (caddr_t)(cp + off), sizeof(struct in_addr));
   1258 			cp[IPOPT_OFFSET] += sizeof(struct in_addr);
   1259 			/*
   1260 			 * Let ip_intr's mcast routing check handle mcast pkts
   1261 			 */
   1262 			forward = !IN_MULTICAST(ip->ip_dst.s_addr);
   1263 			break;
   1264 
   1265 		case IPOPT_RR:
   1266 			if (optlen < IPOPT_OFFSET + sizeof(*cp)) {
   1267 				code = &cp[IPOPT_OLEN] - (u_char *)ip;
   1268 				goto bad;
   1269 			}
   1270 			if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
   1271 				code = &cp[IPOPT_OFFSET] - (u_char *)ip;
   1272 				goto bad;
   1273 			}
   1274 			/*
   1275 			 * If no space remains, ignore.
   1276 			 */
   1277 			off--;			/* 0 origin */
   1278 			if ((off + sizeof(struct in_addr)) > optlen)
   1279 				break;
   1280 			bcopy((caddr_t)(&ip->ip_dst), (caddr_t)&ipaddr.sin_addr,
   1281 			    sizeof(ipaddr.sin_addr));
   1282 			/*
   1283 			 * locate outgoing interface; if we're the destination,
   1284 			 * use the incoming interface (should be same).
   1285 			 */
   1286 			if ((ia = ifatoia(ifa_ifwithaddr(sintosa(&ipaddr))))
   1287 			    == NULL &&
   1288 			    (ia = ip_rtaddr(ipaddr.sin_addr)) == NULL) {
   1289 				type = ICMP_UNREACH;
   1290 				code = ICMP_UNREACH_HOST;
   1291 				goto bad;
   1292 			}
   1293 			bcopy((caddr_t)&ia->ia_addr.sin_addr,
   1294 			    (caddr_t)(cp + off), sizeof(struct in_addr));
   1295 			cp[IPOPT_OFFSET] += sizeof(struct in_addr);
   1296 			break;
   1297 
   1298 		case IPOPT_TS:
   1299 			code = cp - (u_char *)ip;
   1300 			ipt = (struct ip_timestamp *)cp;
   1301 			if (ipt->ipt_len < 4 || ipt->ipt_len > 40) {
   1302 				code = (u_char *)&ipt->ipt_len - (u_char *)ip;
   1303 				goto bad;
   1304 			}
   1305 			if (ipt->ipt_ptr < 5) {
   1306 				code = (u_char *)&ipt->ipt_ptr - (u_char *)ip;
   1307 				goto bad;
   1308 			}
   1309 			if (ipt->ipt_ptr > ipt->ipt_len - sizeof (int32_t)) {
   1310 				if (++ipt->ipt_oflw == 0) {
   1311 					code = (u_char *)&ipt->ipt_ptr -
   1312 					    (u_char *)ip;
   1313 					goto bad;
   1314 				}
   1315 				break;
   1316 			}
   1317 			cp0 = (cp + ipt->ipt_ptr - 1);
   1318 			switch (ipt->ipt_flg) {
   1319 
   1320 			case IPOPT_TS_TSONLY:
   1321 				break;
   1322 
   1323 			case IPOPT_TS_TSANDADDR:
   1324 				if (ipt->ipt_ptr - 1 + sizeof(n_time) +
   1325 				    sizeof(struct in_addr) > ipt->ipt_len) {
   1326 					code = (u_char *)&ipt->ipt_ptr -
   1327 					    (u_char *)ip;
   1328 					goto bad;
   1329 				}
   1330 				ipaddr.sin_addr = dst;
   1331 				ia = ifatoia(ifaof_ifpforaddr(sintosa(&ipaddr),
   1332 				    m->m_pkthdr.rcvif));
   1333 				if (ia == 0)
   1334 					continue;
   1335 				bcopy(&ia->ia_addr.sin_addr,
   1336 				    cp0, sizeof(struct in_addr));
   1337 				ipt->ipt_ptr += sizeof(struct in_addr);
   1338 				break;
   1339 
   1340 			case IPOPT_TS_PRESPEC:
   1341 				if (ipt->ipt_ptr - 1 + sizeof(n_time) +
   1342 				    sizeof(struct in_addr) > ipt->ipt_len) {
   1343 					code = (u_char *)&ipt->ipt_ptr -
   1344 					    (u_char *)ip;
   1345 					goto bad;
   1346 				}
   1347 				bcopy(cp0, &ipaddr.sin_addr,
   1348 				    sizeof(struct in_addr));
   1349 				if (ifatoia(ifa_ifwithaddr(sintosa(&ipaddr)))
   1350 				    == NULL)
   1351 					continue;
   1352 				ipt->ipt_ptr += sizeof(struct in_addr);
   1353 				break;
   1354 
   1355 			default:
   1356 				/* XXX can't take &ipt->ipt_flg */
   1357 				code = (u_char *)&ipt->ipt_ptr -
   1358 				    (u_char *)ip + 1;
   1359 				goto bad;
   1360 			}
   1361 			ntime = iptime();
   1362 			cp0 = (u_char *) &ntime; /* XXX grumble, GCC... */
   1363 			bcopy(cp0, (caddr_t)cp + ipt->ipt_ptr - 1,
   1364 			    sizeof(n_time));
   1365 			ipt->ipt_ptr += sizeof(n_time);
   1366 		}
   1367 	}
   1368 	if (forward) {
   1369 		if (ip_forwsrcrt == 0) {
   1370 			type = ICMP_UNREACH;
   1371 			code = ICMP_UNREACH_SRCFAIL;
   1372 			goto bad;
   1373 		}
   1374 		ip_forward(m, 1);
   1375 		return (1);
   1376 	}
   1377 	return (0);
   1378 bad:
   1379 	icmp_error(m, type, code, 0, 0);
   1380 	ipstat.ips_badoptions++;
   1381 	return (1);
   1382 }
   1383 
   1384 /*
   1385  * Given address of next destination (final or next hop),
   1386  * return internet address info of interface to be used to get there.
   1387  */
   1388 struct in_ifaddr *
   1389 ip_rtaddr(dst)
   1390 	 struct in_addr dst;
   1391 {
   1392 	struct sockaddr_in *sin;
   1393 
   1394 	sin = satosin(&ipforward_rt.ro_dst);
   1395 
   1396 	if (ipforward_rt.ro_rt == 0 || !in_hosteq(dst, sin->sin_addr)) {
   1397 		if (ipforward_rt.ro_rt) {
   1398 			RTFREE(ipforward_rt.ro_rt);
   1399 			ipforward_rt.ro_rt = 0;
   1400 		}
   1401 		sin->sin_family = AF_INET;
   1402 		sin->sin_len = sizeof(*sin);
   1403 		sin->sin_addr = dst;
   1404 
   1405 		rtalloc(&ipforward_rt);
   1406 	}
   1407 	if (ipforward_rt.ro_rt == 0)
   1408 		return ((struct in_ifaddr *)0);
   1409 	return (ifatoia(ipforward_rt.ro_rt->rt_ifa));
   1410 }
   1411 
   1412 /*
   1413  * Save incoming source route for use in replies,
   1414  * to be picked up later by ip_srcroute if the receiver is interested.
   1415  */
   1416 void
   1417 save_rte(option, dst)
   1418 	u_char *option;
   1419 	struct in_addr dst;
   1420 {
   1421 	unsigned olen;
   1422 
   1423 	olen = option[IPOPT_OLEN];
   1424 #ifdef DIAGNOSTIC
   1425 	if (ipprintfs)
   1426 		printf("save_rte: olen %d\n", olen);
   1427 #endif /* 0 */
   1428 	if (olen > sizeof(ip_srcrt) - (1 + sizeof(dst)))
   1429 		return;
   1430 	bcopy((caddr_t)option, (caddr_t)ip_srcrt.srcopt, olen);
   1431 	ip_nhops = (olen - IPOPT_OFFSET - 1) / sizeof(struct in_addr);
   1432 	ip_srcrt.dst = dst;
   1433 }
   1434 
   1435 /*
   1436  * Retrieve incoming source route for use in replies,
   1437  * in the same form used by setsockopt.
   1438  * The first hop is placed before the options, will be removed later.
   1439  */
   1440 struct mbuf *
   1441 ip_srcroute()
   1442 {
   1443 	struct in_addr *p, *q;
   1444 	struct mbuf *m;
   1445 
   1446 	if (ip_nhops == 0)
   1447 		return ((struct mbuf *)0);
   1448 	m = m_get(M_DONTWAIT, MT_SOOPTS);
   1449 	if (m == 0)
   1450 		return ((struct mbuf *)0);
   1451 
   1452 	MCLAIM(m, &inetdomain.dom_mowner);
   1453 #define OPTSIZ	(sizeof(ip_srcrt.nop) + sizeof(ip_srcrt.srcopt))
   1454 
   1455 	/* length is (nhops+1)*sizeof(addr) + sizeof(nop + srcrt header) */
   1456 	m->m_len = ip_nhops * sizeof(struct in_addr) + sizeof(struct in_addr) +
   1457 	    OPTSIZ;
   1458 #ifdef DIAGNOSTIC
   1459 	if (ipprintfs)
   1460 		printf("ip_srcroute: nhops %d mlen %d", ip_nhops, m->m_len);
   1461 #endif
   1462 
   1463 	/*
   1464 	 * First save first hop for return route
   1465 	 */
   1466 	p = &ip_srcrt.route[ip_nhops - 1];
   1467 	*(mtod(m, struct in_addr *)) = *p--;
   1468 #ifdef DIAGNOSTIC
   1469 	if (ipprintfs)
   1470 		printf(" hops %x", ntohl(mtod(m, struct in_addr *)->s_addr));
   1471 #endif
   1472 
   1473 	/*
   1474 	 * Copy option fields and padding (nop) to mbuf.
   1475 	 */
   1476 	ip_srcrt.nop = IPOPT_NOP;
   1477 	ip_srcrt.srcopt[IPOPT_OFFSET] = IPOPT_MINOFF;
   1478 	bcopy((caddr_t)&ip_srcrt.nop,
   1479 	    mtod(m, caddr_t) + sizeof(struct in_addr), OPTSIZ);
   1480 	q = (struct in_addr *)(mtod(m, caddr_t) +
   1481 	    sizeof(struct in_addr) + OPTSIZ);
   1482 #undef OPTSIZ
   1483 	/*
   1484 	 * Record return path as an IP source route,
   1485 	 * reversing the path (pointers are now aligned).
   1486 	 */
   1487 	while (p >= ip_srcrt.route) {
   1488 #ifdef DIAGNOSTIC
   1489 		if (ipprintfs)
   1490 			printf(" %x", ntohl(q->s_addr));
   1491 #endif
   1492 		*q++ = *p--;
   1493 	}
   1494 	/*
   1495 	 * Last hop goes to final destination.
   1496 	 */
   1497 	*q = ip_srcrt.dst;
   1498 #ifdef DIAGNOSTIC
   1499 	if (ipprintfs)
   1500 		printf(" %x\n", ntohl(q->s_addr));
   1501 #endif
   1502 	return (m);
   1503 }
   1504 
   1505 /*
   1506  * Strip out IP options, at higher
   1507  * level protocol in the kernel.
   1508  * Second argument is buffer to which options
   1509  * will be moved, and return value is their length.
   1510  * XXX should be deleted; last arg currently ignored.
   1511  */
   1512 void
   1513 ip_stripoptions(m, mopt)
   1514 	struct mbuf *m;
   1515 	struct mbuf *mopt;
   1516 {
   1517 	int i;
   1518 	struct ip *ip = mtod(m, struct ip *);
   1519 	caddr_t opts;
   1520 	int olen;
   1521 
   1522 	olen = (ip->ip_hl << 2) - sizeof (struct ip);
   1523 	opts = (caddr_t)(ip + 1);
   1524 	i = m->m_len - (sizeof (struct ip) + olen);
   1525 	bcopy(opts  + olen, opts, (unsigned)i);
   1526 	m->m_len -= olen;
   1527 	if (m->m_flags & M_PKTHDR)
   1528 		m->m_pkthdr.len -= olen;
   1529 	ip->ip_len = htons(ntohs(ip->ip_len) - olen);
   1530 	ip->ip_hl = sizeof (struct ip) >> 2;
   1531 }
   1532 
   1533 const int inetctlerrmap[PRC_NCMDS] = {
   1534 	0,		0,		0,		0,
   1535 	0,		EMSGSIZE,	EHOSTDOWN,	EHOSTUNREACH,
   1536 	EHOSTUNREACH,	EHOSTUNREACH,	ECONNREFUSED,	ECONNREFUSED,
   1537 	EMSGSIZE,	EHOSTUNREACH,	0,		0,
   1538 	0,		0,		0,		0,
   1539 	ENOPROTOOPT
   1540 };
   1541 
   1542 /*
   1543  * Forward a packet.  If some error occurs return the sender
   1544  * an icmp packet.  Note we can't always generate a meaningful
   1545  * icmp message because icmp doesn't have a large enough repertoire
   1546  * of codes and types.
   1547  *
   1548  * If not forwarding, just drop the packet.  This could be confusing
   1549  * if ipforwarding was zero but some routing protocol was advancing
   1550  * us as a gateway to somewhere.  However, we must let the routing
   1551  * protocol deal with that.
   1552  *
   1553  * The srcrt parameter indicates whether the packet is being forwarded
   1554  * via a source route.
   1555  */
   1556 void
   1557 ip_forward(m, srcrt)
   1558 	struct mbuf *m;
   1559 	int srcrt;
   1560 {
   1561 	struct ip *ip = mtod(m, struct ip *);
   1562 	struct sockaddr_in *sin;
   1563 	struct rtentry *rt;
   1564 	int error, type = 0, code = 0;
   1565 	struct mbuf *mcopy;
   1566 	n_long dest;
   1567 	struct ifnet *destifp;
   1568 #ifdef IPSEC
   1569 	struct ifnet dummyifp;
   1570 #endif
   1571 
   1572 	/*
   1573 	 * We are now in the output path.
   1574 	 */
   1575 	MCLAIM(m, &ip_tx_mowner);
   1576 
   1577 	/*
   1578 	 * Clear any in-bound checksum flags for this packet.
   1579 	 */
   1580 	m->m_pkthdr.csum_flags = 0;
   1581 
   1582 	dest = 0;
   1583 #ifdef DIAGNOSTIC
   1584 	if (ipprintfs)
   1585 		printf("forward: src %2.2x dst %2.2x ttl %x\n",
   1586 		    ntohl(ip->ip_src.s_addr),
   1587 		    ntohl(ip->ip_dst.s_addr), ip->ip_ttl);
   1588 #endif
   1589 	if (m->m_flags & (M_BCAST|M_MCAST) || in_canforward(ip->ip_dst) == 0) {
   1590 		ipstat.ips_cantforward++;
   1591 		m_freem(m);
   1592 		return;
   1593 	}
   1594 	if (ip->ip_ttl <= IPTTLDEC) {
   1595 		icmp_error(m, ICMP_TIMXCEED, ICMP_TIMXCEED_INTRANS, dest, 0);
   1596 		return;
   1597 	}
   1598 	ip->ip_ttl -= IPTTLDEC;
   1599 
   1600 	sin = satosin(&ipforward_rt.ro_dst);
   1601 	if ((rt = ipforward_rt.ro_rt) == 0 ||
   1602 	    !in_hosteq(ip->ip_dst, sin->sin_addr)) {
   1603 		if (ipforward_rt.ro_rt) {
   1604 			RTFREE(ipforward_rt.ro_rt);
   1605 			ipforward_rt.ro_rt = 0;
   1606 		}
   1607 		sin->sin_family = AF_INET;
   1608 		sin->sin_len = sizeof(struct sockaddr_in);
   1609 		sin->sin_addr = ip->ip_dst;
   1610 
   1611 		rtalloc(&ipforward_rt);
   1612 		if (ipforward_rt.ro_rt == 0) {
   1613 			icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, dest, 0);
   1614 			return;
   1615 		}
   1616 		rt = ipforward_rt.ro_rt;
   1617 	}
   1618 
   1619 	/*
   1620 	 * Save at most 68 bytes of the packet in case
   1621 	 * we need to generate an ICMP message to the src.
   1622 	 * Pullup to avoid sharing mbuf cluster between m and mcopy.
   1623 	 */
   1624 	mcopy = m_copym(m, 0, imin(ntohs(ip->ip_len), 68), M_DONTWAIT);
   1625 	if (mcopy)
   1626 		mcopy = m_pullup(mcopy, ip->ip_hl << 2);
   1627 
   1628 	/*
   1629 	 * If forwarding packet using same interface that it came in on,
   1630 	 * perhaps should send a redirect to sender to shortcut a hop.
   1631 	 * Only send redirect if source is sending directly to us,
   1632 	 * and if packet was not source routed (or has any options).
   1633 	 * Also, don't send redirect if forwarding using a default route
   1634 	 * or a route modified by a redirect.
   1635 	 */
   1636 	if (rt->rt_ifp == m->m_pkthdr.rcvif &&
   1637 	    (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0 &&
   1638 	    !in_nullhost(satosin(rt_key(rt))->sin_addr) &&
   1639 	    ipsendredirects && !srcrt) {
   1640 		if (rt->rt_ifa &&
   1641 		    (ip->ip_src.s_addr & ifatoia(rt->rt_ifa)->ia_subnetmask) ==
   1642 		    ifatoia(rt->rt_ifa)->ia_subnet) {
   1643 			if (rt->rt_flags & RTF_GATEWAY)
   1644 				dest = satosin(rt->rt_gateway)->sin_addr.s_addr;
   1645 			else
   1646 				dest = ip->ip_dst.s_addr;
   1647 			/*
   1648 			 * Router requirements says to only send host
   1649 			 * redirects.
   1650 			 */
   1651 			type = ICMP_REDIRECT;
   1652 			code = ICMP_REDIRECT_HOST;
   1653 #ifdef DIAGNOSTIC
   1654 			if (ipprintfs)
   1655 				printf("redirect (%d) to %x\n", code,
   1656 				    (u_int32_t)dest);
   1657 #endif
   1658 		}
   1659 	}
   1660 
   1661 #ifdef IPSEC
   1662 	/* Don't lookup socket in forwarding case */
   1663 	(void)ipsec_setsocket(m, NULL);
   1664 #endif
   1665 	error = ip_output(m, (struct mbuf *)0, &ipforward_rt,
   1666 	    (IP_FORWARDING | (ip_directedbcast ? IP_ALLOWBROADCAST : 0)), 0);
   1667 	if (error)
   1668 		ipstat.ips_cantforward++;
   1669 	else {
   1670 		ipstat.ips_forward++;
   1671 		if (type)
   1672 			ipstat.ips_redirectsent++;
   1673 		else {
   1674 			if (mcopy) {
   1675 #ifdef GATEWAY
   1676 				if (mcopy->m_flags & M_CANFASTFWD)
   1677 					ipflow_create(&ipforward_rt, mcopy);
   1678 #endif
   1679 				m_freem(mcopy);
   1680 			}
   1681 			return;
   1682 		}
   1683 	}
   1684 	if (mcopy == NULL)
   1685 		return;
   1686 	destifp = NULL;
   1687 
   1688 	switch (error) {
   1689 
   1690 	case 0:				/* forwarded, but need redirect */
   1691 		/* type, code set above */
   1692 		break;
   1693 
   1694 	case ENETUNREACH:		/* shouldn't happen, checked above */
   1695 	case EHOSTUNREACH:
   1696 	case ENETDOWN:
   1697 	case EHOSTDOWN:
   1698 	default:
   1699 		type = ICMP_UNREACH;
   1700 		code = ICMP_UNREACH_HOST;
   1701 		break;
   1702 
   1703 	case EMSGSIZE:
   1704 		type = ICMP_UNREACH;
   1705 		code = ICMP_UNREACH_NEEDFRAG;
   1706 #ifndef IPSEC
   1707 		if (ipforward_rt.ro_rt)
   1708 			destifp = ipforward_rt.ro_rt->rt_ifp;
   1709 #else
   1710 		/*
   1711 		 * If the packet is routed over IPsec tunnel, tell the
   1712 		 * originator the tunnel MTU.
   1713 		 *	tunnel MTU = if MTU - sizeof(IP) - ESP/AH hdrsiz
   1714 		 * XXX quickhack!!!
   1715 		 */
   1716 		if (ipforward_rt.ro_rt) {
   1717 			struct secpolicy *sp;
   1718 			int ipsecerror;
   1719 			size_t ipsechdr;
   1720 			struct route *ro;
   1721 
   1722 			sp = ipsec4_getpolicybyaddr(mcopy,
   1723 			                            IPSEC_DIR_OUTBOUND,
   1724 			                            IP_FORWARDING,
   1725 			                            &ipsecerror);
   1726 
   1727 			if (sp == NULL)
   1728 				destifp = ipforward_rt.ro_rt->rt_ifp;
   1729 			else {
   1730 				/* count IPsec header size */
   1731 				ipsechdr = ipsec4_hdrsiz(mcopy,
   1732 				                         IPSEC_DIR_OUTBOUND,
   1733 				                         NULL);
   1734 
   1735 				/*
   1736 				 * find the correct route for outer IPv4
   1737 				 * header, compute tunnel MTU.
   1738 				 *
   1739 				 * XXX BUG ALERT
   1740 				 * The "dummyifp" code relies upon the fact
   1741 				 * that icmp_error() touches only ifp->if_mtu.
   1742 				 */
   1743 				/*XXX*/
   1744 				destifp = NULL;
   1745 				if (sp->req != NULL
   1746 				 && sp->req->sav != NULL
   1747 				 && sp->req->sav->sah != NULL) {
   1748 					ro = &sp->req->sav->sah->sa_route;
   1749 					if (ro->ro_rt && ro->ro_rt->rt_ifp) {
   1750 						dummyifp.if_mtu =
   1751 						    ro->ro_rt->rt_rmx.rmx_mtu ?
   1752 						    ro->ro_rt->rt_rmx.rmx_mtu :
   1753 						    ro->ro_rt->rt_ifp->if_mtu;
   1754 						dummyifp.if_mtu -= ipsechdr;
   1755 						destifp = &dummyifp;
   1756 					}
   1757 				}
   1758 
   1759 				key_freesp(sp);
   1760 			}
   1761 		}
   1762 #endif /*IPSEC*/
   1763 		ipstat.ips_cantfrag++;
   1764 		break;
   1765 
   1766 	case ENOBUFS:
   1767 #if 1
   1768 		/*
   1769 		 * a router should not generate ICMP_SOURCEQUENCH as
   1770 		 * required in RFC1812 Requirements for IP Version 4 Routers.
   1771 		 * source quench could be a big problem under DoS attacks,
   1772 		 * or if the underlying interface is rate-limited.
   1773 		 */
   1774 		if (mcopy)
   1775 			m_freem(mcopy);
   1776 		return;
   1777 #else
   1778 		type = ICMP_SOURCEQUENCH;
   1779 		code = 0;
   1780 		break;
   1781 #endif
   1782 	}
   1783 	icmp_error(mcopy, type, code, dest, destifp);
   1784 }
   1785 
   1786 void
   1787 ip_savecontrol(inp, mp, ip, m)
   1788 	struct inpcb *inp;
   1789 	struct mbuf **mp;
   1790 	struct ip *ip;
   1791 	struct mbuf *m;
   1792 {
   1793 
   1794 	if (inp->inp_socket->so_options & SO_TIMESTAMP) {
   1795 		struct timeval tv;
   1796 
   1797 		microtime(&tv);
   1798 		*mp = sbcreatecontrol((caddr_t) &tv, sizeof(tv),
   1799 		    SCM_TIMESTAMP, SOL_SOCKET);
   1800 		if (*mp)
   1801 			mp = &(*mp)->m_next;
   1802 	}
   1803 	if (inp->inp_flags & INP_RECVDSTADDR) {
   1804 		*mp = sbcreatecontrol((caddr_t) &ip->ip_dst,
   1805 		    sizeof(struct in_addr), IP_RECVDSTADDR, IPPROTO_IP);
   1806 		if (*mp)
   1807 			mp = &(*mp)->m_next;
   1808 	}
   1809 #ifdef notyet
   1810 	/*
   1811 	 * XXX
   1812 	 * Moving these out of udp_input() made them even more broken
   1813 	 * than they already were.
   1814 	 *	- fenner (at) parc.xerox.com
   1815 	 */
   1816 	/* options were tossed already */
   1817 	if (inp->inp_flags & INP_RECVOPTS) {
   1818 		*mp = sbcreatecontrol((caddr_t) opts_deleted_above,
   1819 		    sizeof(struct in_addr), IP_RECVOPTS, IPPROTO_IP);
   1820 		if (*mp)
   1821 			mp = &(*mp)->m_next;
   1822 	}
   1823 	/* ip_srcroute doesn't do what we want here, need to fix */
   1824 	if (inp->inp_flags & INP_RECVRETOPTS) {
   1825 		*mp = sbcreatecontrol((caddr_t) ip_srcroute(),
   1826 		    sizeof(struct in_addr), IP_RECVRETOPTS, IPPROTO_IP);
   1827 		if (*mp)
   1828 			mp = &(*mp)->m_next;
   1829 	}
   1830 #endif
   1831 	if (inp->inp_flags & INP_RECVIF) {
   1832 		struct sockaddr_dl sdl;
   1833 
   1834 		sdl.sdl_len = offsetof(struct sockaddr_dl, sdl_data[0]);
   1835 		sdl.sdl_family = AF_LINK;
   1836 		sdl.sdl_index = m->m_pkthdr.rcvif ?
   1837 		    m->m_pkthdr.rcvif->if_index : 0;
   1838 		sdl.sdl_nlen = sdl.sdl_alen = sdl.sdl_slen = 0;
   1839 		*mp = sbcreatecontrol((caddr_t) &sdl, sdl.sdl_len,
   1840 		    IP_RECVIF, IPPROTO_IP);
   1841 		if (*mp)
   1842 			mp = &(*mp)->m_next;
   1843 	}
   1844 }
   1845 
   1846 int
   1847 ip_sysctl(name, namelen, oldp, oldlenp, newp, newlen)
   1848 	int *name;
   1849 	u_int namelen;
   1850 	void *oldp;
   1851 	size_t *oldlenp;
   1852 	void *newp;
   1853 	size_t newlen;
   1854 {
   1855 	extern int subnetsarelocal, hostzeroisbroadcast;
   1856 
   1857 	int error, old;
   1858 
   1859 	/* All sysctl names at this level are terminal. */
   1860 	if (namelen != 1)
   1861 		return (ENOTDIR);
   1862 
   1863 	switch (name[0]) {
   1864 	case IPCTL_FORWARDING:
   1865 		return (sysctl_int(oldp, oldlenp, newp, newlen, &ipforwarding));
   1866 	case IPCTL_SENDREDIRECTS:
   1867 		return (sysctl_int(oldp, oldlenp, newp, newlen,
   1868 			&ipsendredirects));
   1869 	case IPCTL_DEFTTL:
   1870 		return (sysctl_int(oldp, oldlenp, newp, newlen, &ip_defttl));
   1871 #ifdef notyet
   1872 	case IPCTL_DEFMTU:
   1873 		return (sysctl_int(oldp, oldlenp, newp, newlen, &ip_mtu));
   1874 #endif
   1875 	case IPCTL_FORWSRCRT:
   1876 		/* Don't allow this to change in a secure environment.  */
   1877 		if (securelevel > 0)
   1878 			return (sysctl_rdint(oldp, oldlenp, newp,
   1879 			    ip_forwsrcrt));
   1880 		else
   1881 			return (sysctl_int(oldp, oldlenp, newp, newlen,
   1882 			    &ip_forwsrcrt));
   1883 	case IPCTL_DIRECTEDBCAST:
   1884 		return (sysctl_int(oldp, oldlenp, newp, newlen,
   1885 		    &ip_directedbcast));
   1886 	case IPCTL_ALLOWSRCRT:
   1887 		return (sysctl_int(oldp, oldlenp, newp, newlen,
   1888 		    &ip_allowsrcrt));
   1889 	case IPCTL_SUBNETSARELOCAL:
   1890 		return (sysctl_int(oldp, oldlenp, newp, newlen,
   1891 		    &subnetsarelocal));
   1892 	case IPCTL_MTUDISC:
   1893 		error = sysctl_int(oldp, oldlenp, newp, newlen,
   1894 		    &ip_mtudisc);
   1895 		if (error == 0 && ip_mtudisc == 0)
   1896 			rt_timer_queue_remove_all(ip_mtudisc_timeout_q, TRUE);
   1897 		return error;
   1898 	case IPCTL_ANONPORTMIN:
   1899 		old = anonportmin;
   1900 		error = sysctl_int(oldp, oldlenp, newp, newlen, &anonportmin);
   1901 		if (anonportmin >= anonportmax || anonportmin < 0
   1902 		    || anonportmin > 65535
   1903 #ifndef IPNOPRIVPORTS
   1904 		    || anonportmin < IPPORT_RESERVED
   1905 #endif
   1906 		    ) {
   1907 			anonportmin = old;
   1908 			return (EINVAL);
   1909 		}
   1910 		return (error);
   1911 	case IPCTL_ANONPORTMAX:
   1912 		old = anonportmax;
   1913 		error = sysctl_int(oldp, oldlenp, newp, newlen, &anonportmax);
   1914 		if (anonportmin >= anonportmax || anonportmax < 0
   1915 		    || anonportmax > 65535
   1916 #ifndef IPNOPRIVPORTS
   1917 		    || anonportmax < IPPORT_RESERVED
   1918 #endif
   1919 		    ) {
   1920 			anonportmax = old;
   1921 			return (EINVAL);
   1922 		}
   1923 		return (error);
   1924 	case IPCTL_MTUDISCTIMEOUT:
   1925 		old = ip_mtudisc_timeout;
   1926 		error = sysctl_int(oldp, oldlenp, newp, newlen,
   1927 		   &ip_mtudisc_timeout);
   1928 		if (ip_mtudisc_timeout < 0) {
   1929 			ip_mtudisc_timeout = old;
   1930 			return (EINVAL);
   1931 		}
   1932 		if (error == 0)
   1933 			rt_timer_queue_change(ip_mtudisc_timeout_q,
   1934 					      ip_mtudisc_timeout);
   1935 		return (error);
   1936 #ifdef GATEWAY
   1937 	case IPCTL_MAXFLOWS:
   1938 	    {
   1939 		int s;
   1940 
   1941 		error = sysctl_int(oldp, oldlenp, newp, newlen,
   1942 		   &ip_maxflows);
   1943 		s = splsoftnet();
   1944 		ipflow_reap(0);
   1945 		splx(s);
   1946 		return (error);
   1947 	    }
   1948 #endif
   1949 	case IPCTL_HOSTZEROBROADCAST:
   1950 		return (sysctl_int(oldp, oldlenp, newp, newlen,
   1951 		    &hostzeroisbroadcast));
   1952 #if NGIF > 0
   1953 	case IPCTL_GIF_TTL:
   1954 		return (sysctl_int(oldp, oldlenp, newp, newlen,
   1955 				  &ip_gif_ttl));
   1956 #endif
   1957 
   1958 #if NGRE > 0
   1959 	case IPCTL_GRE_TTL:
   1960 		return (sysctl_int(oldp, oldlenp, newp, newlen,
   1961 				  &ip_gre_ttl));
   1962 #endif
   1963 
   1964 #ifndef IPNOPRIVPORTS
   1965 	case IPCTL_LOWPORTMIN:
   1966 		old = lowportmin;
   1967 		error = sysctl_int(oldp, oldlenp, newp, newlen, &lowportmin);
   1968 		if (lowportmin >= lowportmax
   1969 		    || lowportmin > IPPORT_RESERVEDMAX
   1970 		    || lowportmin < IPPORT_RESERVEDMIN
   1971 		    ) {
   1972 			lowportmin = old;
   1973 			return (EINVAL);
   1974 		}
   1975 		return (error);
   1976 	case IPCTL_LOWPORTMAX:
   1977 		old = lowportmax;
   1978 		error = sysctl_int(oldp, oldlenp, newp, newlen, &lowportmax);
   1979 		if (lowportmin >= lowportmax
   1980 		    || lowportmax > IPPORT_RESERVEDMAX
   1981 		    || lowportmax < IPPORT_RESERVEDMIN
   1982 		    ) {
   1983 			lowportmax = old;
   1984 			return (EINVAL);
   1985 		}
   1986 		return (error);
   1987 #endif
   1988 
   1989 	case IPCTL_MAXFRAGPACKETS:
   1990 		return (sysctl_int(oldp, oldlenp, newp, newlen,
   1991 		    &ip_maxfragpackets));
   1992 
   1993 	case IPCTL_CHECKINTERFACE:
   1994 		return (sysctl_int(oldp, oldlenp, newp, newlen,
   1995 		    &ip_checkinterface));
   1996 	default:
   1997 		return (EOPNOTSUPP);
   1998 	}
   1999 	/* NOTREACHED */
   2000 }
   2001