Home | History | Annotate | Line # | Download | only in netinet
ip_input.c revision 1.170
      1 /*	$NetBSD: ip_input.c,v 1.170 2003/07/03 05:03:53 itojun 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 1.170 2003/07/03 05:03:53 itojun 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_mbuftrace.h"
    112 #include "opt_inet_csum.h"
    113 
    114 #include <sys/param.h>
    115 #include <sys/systm.h>
    116 #include <sys/malloc.h>
    117 #include <sys/mbuf.h>
    118 #include <sys/domain.h>
    119 #include <sys/protosw.h>
    120 #include <sys/socket.h>
    121 #include <sys/socketvar.h>
    122 #include <sys/errno.h>
    123 #include <sys/time.h>
    124 #include <sys/kernel.h>
    125 #include <sys/pool.h>
    126 #include <sys/sysctl.h>
    127 
    128 #include <net/if.h>
    129 #include <net/if_dl.h>
    130 #include <net/route.h>
    131 #include <net/pfil.h>
    132 
    133 #include <netinet/in.h>
    134 #include <netinet/in_systm.h>
    135 #include <netinet/ip.h>
    136 #include <netinet/in_pcb.h>
    137 #include <netinet/in_var.h>
    138 #include <netinet/ip_var.h>
    139 #include <netinet/ip_icmp.h>
    140 /* just for gif_ttl */
    141 #include <netinet/in_gif.h>
    142 #include "gif.h"
    143 #include <net/if_gre.h>
    144 #include "gre.h"
    145 
    146 #ifdef MROUTING
    147 #include <netinet/ip_mroute.h>
    148 #endif
    149 
    150 #ifdef IPSEC
    151 #include <netinet6/ipsec.h>
    152 #include <netkey/key.h>
    153 #endif
    154 
    155 #ifndef	IPFORWARDING
    156 #ifdef GATEWAY
    157 #define	IPFORWARDING	1	/* forward IP packets not for us */
    158 #else /* GATEWAY */
    159 #define	IPFORWARDING	0	/* don't forward IP packets not for us */
    160 #endif /* GATEWAY */
    161 #endif /* IPFORWARDING */
    162 #ifndef	IPSENDREDIRECTS
    163 #define	IPSENDREDIRECTS	1
    164 #endif
    165 #ifndef IPFORWSRCRT
    166 #define	IPFORWSRCRT	1	/* forward source-routed packets */
    167 #endif
    168 #ifndef IPALLOWSRCRT
    169 #define	IPALLOWSRCRT	1	/* allow source-routed packets */
    170 #endif
    171 #ifndef IPMTUDISC
    172 #define IPMTUDISC	1
    173 #endif
    174 #ifndef IPMTUDISCTIMEOUT
    175 #define IPMTUDISCTIMEOUT (10 * 60)	/* as per RFC 1191 */
    176 #endif
    177 
    178 /*
    179  * Note: DIRECTED_BROADCAST is handled this way so that previous
    180  * configuration using this option will Just Work.
    181  */
    182 #ifndef IPDIRECTEDBCAST
    183 #ifdef DIRECTED_BROADCAST
    184 #define IPDIRECTEDBCAST	1
    185 #else
    186 #define	IPDIRECTEDBCAST	0
    187 #endif /* DIRECTED_BROADCAST */
    188 #endif /* IPDIRECTEDBCAST */
    189 int	ipforwarding = IPFORWARDING;
    190 int	ipsendredirects = IPSENDREDIRECTS;
    191 int	ip_defttl = IPDEFTTL;
    192 int	ip_forwsrcrt = IPFORWSRCRT;
    193 int	ip_directedbcast = IPDIRECTEDBCAST;
    194 int	ip_allowsrcrt = IPALLOWSRCRT;
    195 int	ip_mtudisc = IPMTUDISC;
    196 int	ip_mtudisc_timeout = IPMTUDISCTIMEOUT;
    197 #ifdef DIAGNOSTIC
    198 int	ipprintfs = 0;
    199 #endif
    200 /*
    201  * XXX - Setting ip_checkinterface mostly implements the receive side of
    202  * the Strong ES model described in RFC 1122, but since the routing table
    203  * and transmit implementation do not implement the Strong ES model,
    204  * setting this to 1 results in an odd hybrid.
    205  *
    206  * XXX - ip_checkinterface currently must be disabled if you use ipnat
    207  * to translate the destination address to another local interface.
    208  *
    209  * XXX - ip_checkinterface must be disabled if you add IP aliases
    210  * to the loopback interface instead of the interface where the
    211  * packets for those addresses are received.
    212  */
    213 int	ip_checkinterface = 0;
    214 
    215 
    216 struct rttimer_queue *ip_mtudisc_timeout_q = NULL;
    217 
    218 extern	struct domain inetdomain;
    219 int	ipqmaxlen = IFQ_MAXLEN;
    220 u_long	in_ifaddrhash;				/* size of hash table - 1 */
    221 int	in_ifaddrentries;			/* total number of addrs */
    222 struct	in_ifaddrhead in_ifaddr;
    223 struct	in_ifaddrhashhead *in_ifaddrhashtbl;
    224 u_long	in_multihash;				/* size of hash table - 1 */
    225 int	in_multientries;			/* total number of addrs */
    226 struct	in_multihead in_multi;
    227 struct	in_multihashhead *in_multihashtbl;
    228 struct	ifqueue ipintrq;
    229 struct	ipstat	ipstat;
    230 u_int16_t	ip_id;
    231 
    232 #ifdef PFIL_HOOKS
    233 struct pfil_head inet_pfil_hook;
    234 #endif
    235 
    236 struct ipqhead ipq;
    237 int	ipq_locked;
    238 int	ip_nfragpackets = 0;
    239 int	ip_maxfragpackets = 200;
    240 
    241 static __inline int ipq_lock_try __P((void));
    242 static __inline void ipq_unlock __P((void));
    243 
    244 static __inline int
    245 ipq_lock_try()
    246 {
    247 	int s;
    248 
    249 	/*
    250 	 * Use splvm() -- we're blocking things that would cause
    251 	 * mbuf allocation.
    252 	 */
    253 	s = splvm();
    254 	if (ipq_locked) {
    255 		splx(s);
    256 		return (0);
    257 	}
    258 	ipq_locked = 1;
    259 	splx(s);
    260 	return (1);
    261 }
    262 
    263 static __inline void
    264 ipq_unlock()
    265 {
    266 	int s;
    267 
    268 	s = splvm();
    269 	ipq_locked = 0;
    270 	splx(s);
    271 }
    272 
    273 #ifdef DIAGNOSTIC
    274 #define	IPQ_LOCK()							\
    275 do {									\
    276 	if (ipq_lock_try() == 0) {					\
    277 		printf("%s:%d: ipq already locked\n", __FILE__, __LINE__); \
    278 		panic("ipq_lock");					\
    279 	}								\
    280 } while (/*CONSTCOND*/ 0)
    281 #define	IPQ_LOCK_CHECK()						\
    282 do {									\
    283 	if (ipq_locked == 0) {						\
    284 		printf("%s:%d: ipq lock not held\n", __FILE__, __LINE__); \
    285 		panic("ipq lock check");				\
    286 	}								\
    287 } while (/*CONSTCOND*/ 0)
    288 #else
    289 #define	IPQ_LOCK()		(void) ipq_lock_try()
    290 #define	IPQ_LOCK_CHECK()	/* nothing */
    291 #endif
    292 
    293 #define	IPQ_UNLOCK()		ipq_unlock()
    294 
    295 struct pool inmulti_pool;
    296 struct pool ipqent_pool;
    297 
    298 #ifdef INET_CSUM_COUNTERS
    299 #include <sys/device.h>
    300 
    301 struct evcnt ip_hwcsum_bad = EVCNT_INITIALIZER(EVCNT_TYPE_MISC,
    302     NULL, "inet", "hwcsum bad");
    303 struct evcnt ip_hwcsum_ok = EVCNT_INITIALIZER(EVCNT_TYPE_MISC,
    304     NULL, "inet", "hwcsum ok");
    305 struct evcnt ip_swcsum = EVCNT_INITIALIZER(EVCNT_TYPE_MISC,
    306     NULL, "inet", "swcsum");
    307 
    308 #define	INET_CSUM_COUNTER_INCR(ev)	(ev)->ev_count++
    309 
    310 #else
    311 
    312 #define	INET_CSUM_COUNTER_INCR(ev)	/* nothing */
    313 
    314 #endif /* INET_CSUM_COUNTERS */
    315 
    316 /*
    317  * We need to save the IP options in case a protocol wants to respond
    318  * to an incoming packet over the same route if the packet got here
    319  * using IP source routing.  This allows connection establishment and
    320  * maintenance when the remote end is on a network that is not known
    321  * to us.
    322  */
    323 int	ip_nhops = 0;
    324 static	struct ip_srcrt {
    325 	struct	in_addr dst;			/* final destination */
    326 	char	nop;				/* one NOP to align */
    327 	char	srcopt[IPOPT_OFFSET + 1];	/* OPTVAL, OLEN and OFFSET */
    328 	struct	in_addr route[MAX_IPOPTLEN/sizeof(struct in_addr)];
    329 } ip_srcrt;
    330 
    331 static void save_rte __P((u_char *, struct in_addr));
    332 
    333 #ifdef MBUFTRACE
    334 struct mowner ip_rx_mowner = { "internet", "rx" };
    335 struct mowner ip_tx_mowner = { "internet", "tx" };
    336 #endif
    337 
    338 /*
    339  * IP initialization: fill in IP protocol switch table.
    340  * All protocols not implemented in kernel go to raw IP protocol handler.
    341  */
    342 void
    343 ip_init()
    344 {
    345 	struct protosw *pr;
    346 	int i;
    347 
    348 	pool_init(&inmulti_pool, sizeof(struct in_multi), 0, 0, 0, "inmltpl",
    349 	    NULL);
    350 	pool_init(&ipqent_pool, sizeof(struct ipqent), 0, 0, 0, "ipqepl",
    351 	    NULL);
    352 
    353 	pr = pffindproto(PF_INET, IPPROTO_RAW, SOCK_RAW);
    354 	if (pr == 0)
    355 		panic("ip_init");
    356 	for (i = 0; i < IPPROTO_MAX; i++)
    357 		ip_protox[i] = pr - inetsw;
    358 	for (pr = inetdomain.dom_protosw;
    359 	    pr < inetdomain.dom_protoswNPROTOSW; pr++)
    360 		if (pr->pr_domain->dom_family == PF_INET &&
    361 		    pr->pr_protocol && pr->pr_protocol != IPPROTO_RAW)
    362 			ip_protox[pr->pr_protocol] = pr - inetsw;
    363 	LIST_INIT(&ipq);
    364 	ip_id = time.tv_sec & 0xffff;
    365 	ipintrq.ifq_maxlen = ipqmaxlen;
    366 	TAILQ_INIT(&in_ifaddr);
    367 	in_ifaddrhashtbl = hashinit(IN_IFADDR_HASH_SIZE, HASH_LIST, M_IFADDR,
    368 	    M_WAITOK, &in_ifaddrhash);
    369 	in_multihashtbl = hashinit(IN_IFADDR_HASH_SIZE, HASH_LIST, M_IPMADDR,
    370 	    M_WAITOK, &in_multihash);
    371 	ip_mtudisc_timeout_q = rt_timer_queue_create(ip_mtudisc_timeout);
    372 #ifdef GATEWAY
    373 	ipflow_init();
    374 #endif
    375 
    376 #ifdef PFIL_HOOKS
    377 	/* Register our Packet Filter hook. */
    378 	inet_pfil_hook.ph_type = PFIL_TYPE_AF;
    379 	inet_pfil_hook.ph_af   = AF_INET;
    380 	i = pfil_head_register(&inet_pfil_hook);
    381 	if (i != 0)
    382 		printf("ip_init: WARNING: unable to register pfil hook, "
    383 		    "error %d\n", i);
    384 #endif /* PFIL_HOOKS */
    385 
    386 #ifdef INET_CSUM_COUNTERS
    387 	evcnt_attach_static(&ip_hwcsum_bad);
    388 	evcnt_attach_static(&ip_hwcsum_ok);
    389 	evcnt_attach_static(&ip_swcsum);
    390 #endif /* INET_CSUM_COUNTERS */
    391 
    392 #ifdef MBUFTRACE
    393 	MOWNER_ATTACH(&ip_tx_mowner);
    394 	MOWNER_ATTACH(&ip_rx_mowner);
    395 #endif /* MBUFTRACE */
    396 }
    397 
    398 struct	sockaddr_in ipaddr = { sizeof(ipaddr), AF_INET };
    399 struct	route ipforward_rt;
    400 
    401 /*
    402  * IP software interrupt routine
    403  */
    404 void
    405 ipintr()
    406 {
    407 	int s;
    408 	struct mbuf *m;
    409 
    410 	while (1) {
    411 		s = splnet();
    412 		IF_DEQUEUE(&ipintrq, m);
    413 		splx(s);
    414 		if (m == 0)
    415 			return;
    416 		MCLAIM(m, &ip_rx_mowner);
    417 		ip_input(m);
    418 	}
    419 }
    420 
    421 /*
    422  * Ip input routine.  Checksum and byte swap header.  If fragmented
    423  * try to reassemble.  Process options.  Pass to next level.
    424  */
    425 void
    426 ip_input(struct mbuf *m)
    427 {
    428 	struct ip *ip = NULL;
    429 	struct ipq *fp;
    430 	struct in_ifaddr *ia;
    431 	struct ifaddr *ifa;
    432 	struct ipqent *ipqe;
    433 	int hlen = 0, mff, len;
    434 	int downmatch;
    435 	int checkif;
    436 	int srcrt = 0;
    437 
    438 	MCLAIM(m, &ip_rx_mowner);
    439 #ifdef	DIAGNOSTIC
    440 	if ((m->m_flags & M_PKTHDR) == 0)
    441 		panic("ipintr no HDR");
    442 #endif
    443 #ifdef IPSEC
    444 	/*
    445 	 * should the inner packet be considered authentic?
    446 	 * see comment in ah4_input().
    447 	 */
    448 	if (m) {
    449 		m->m_flags &= ~M_AUTHIPHDR;
    450 		m->m_flags &= ~M_AUTHIPDGM;
    451 	}
    452 #endif
    453 
    454 	/*
    455 	 * If no IP addresses have been set yet but the interfaces
    456 	 * are receiving, can't do anything with incoming packets yet.
    457 	 */
    458 	if (TAILQ_FIRST(&in_ifaddr) == 0)
    459 		goto bad;
    460 	ipstat.ips_total++;
    461 	/*
    462 	 * If the IP header is not aligned, slurp it up into a new
    463 	 * mbuf with space for link headers, in the event we forward
    464 	 * it.  Otherwise, if it is aligned, make sure the entire
    465 	 * base IP header is in the first mbuf of the chain.
    466 	 */
    467 	if (IP_HDR_ALIGNED_P(mtod(m, caddr_t)) == 0) {
    468 		if ((m = m_copyup(m, sizeof(struct ip),
    469 				  (max_linkhdr + 3) & ~3)) == NULL) {
    470 			/* XXXJRT new stat, please */
    471 			ipstat.ips_toosmall++;
    472 			return;
    473 		}
    474 	} else if (__predict_false(m->m_len < sizeof (struct ip))) {
    475 		if ((m = m_pullup(m, sizeof (struct ip))) == NULL) {
    476 			ipstat.ips_toosmall++;
    477 			return;
    478 		}
    479 	}
    480 	ip = mtod(m, struct ip *);
    481 	if (ip->ip_v != IPVERSION) {
    482 		ipstat.ips_badvers++;
    483 		goto bad;
    484 	}
    485 	hlen = ip->ip_hl << 2;
    486 	if (hlen < sizeof(struct ip)) {	/* minimum header length */
    487 		ipstat.ips_badhlen++;
    488 		goto bad;
    489 	}
    490 	if (hlen > m->m_len) {
    491 		if ((m = m_pullup(m, hlen)) == 0) {
    492 			ipstat.ips_badhlen++;
    493 			return;
    494 		}
    495 		ip = mtod(m, struct ip *);
    496 	}
    497 
    498 	/*
    499 	 * RFC1122: packets with a multicast source address are
    500 	 * not allowed.
    501 	 */
    502 	if (IN_MULTICAST(ip->ip_src.s_addr)) {
    503 		ipstat.ips_badaddr++;
    504 		goto bad;
    505 	}
    506 
    507 	/* 127/8 must not appear on wire - RFC1122 */
    508 	if ((ntohl(ip->ip_dst.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET ||
    509 	    (ntohl(ip->ip_src.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET) {
    510 		if ((m->m_pkthdr.rcvif->if_flags & IFF_LOOPBACK) == 0) {
    511 			ipstat.ips_badaddr++;
    512 			goto bad;
    513 		}
    514 	}
    515 
    516 	switch (m->m_pkthdr.csum_flags &
    517 		((m->m_pkthdr.rcvif->if_csum_flags_rx & M_CSUM_IPv4) |
    518 		 M_CSUM_IPv4_BAD)) {
    519 	case M_CSUM_IPv4|M_CSUM_IPv4_BAD:
    520 		INET_CSUM_COUNTER_INCR(&ip_hwcsum_bad);
    521 		goto badcsum;
    522 
    523 	case M_CSUM_IPv4:
    524 		/* Checksum was okay. */
    525 		INET_CSUM_COUNTER_INCR(&ip_hwcsum_ok);
    526 		break;
    527 
    528 	default:
    529 		/* Must compute it ourselves. */
    530 		INET_CSUM_COUNTER_INCR(&ip_swcsum);
    531 		if (in_cksum(m, hlen) != 0)
    532 			goto bad;
    533 		break;
    534 	}
    535 
    536 	/* Retrieve the packet length. */
    537 	len = ntohs(ip->ip_len);
    538 
    539 	/*
    540 	 * Check for additional length bogosity
    541 	 */
    542 	if (len < hlen) {
    543 	 	ipstat.ips_badlen++;
    544 		goto bad;
    545 	}
    546 
    547 	/*
    548 	 * Check that the amount of data in the buffers
    549 	 * is as at least much as the IP header would have us expect.
    550 	 * Trim mbufs if longer than we expect.
    551 	 * Drop packet if shorter than we expect.
    552 	 */
    553 	if (m->m_pkthdr.len < len) {
    554 		ipstat.ips_tooshort++;
    555 		goto bad;
    556 	}
    557 	if (m->m_pkthdr.len > len) {
    558 		if (m->m_len == m->m_pkthdr.len) {
    559 			m->m_len = len;
    560 			m->m_pkthdr.len = len;
    561 		} else
    562 			m_adj(m, len - m->m_pkthdr.len);
    563 	}
    564 
    565 #ifdef IPSEC
    566 	/* ipflow (IP fast forwarding) is not compatible with IPsec. */
    567 	m->m_flags &= ~M_CANFASTFWD;
    568 #else
    569 	/*
    570 	 * Assume that we can create a fast-forward IP flow entry
    571 	 * based on this packet.
    572 	 */
    573 	m->m_flags |= M_CANFASTFWD;
    574 #endif
    575 
    576 #ifdef PFIL_HOOKS
    577 	/*
    578 	 * Run through list of hooks for input packets.  If there are any
    579 	 * filters which require that additional packets in the flow are
    580 	 * not fast-forwarded, they must clear the M_CANFASTFWD flag.
    581 	 * Note that filters must _never_ set this flag, as another filter
    582 	 * in the list may have previously cleared it.
    583 	 */
    584 	/*
    585 	 * let ipfilter look at packet on the wire,
    586 	 * not the decapsulated packet.
    587 	 */
    588 #ifdef IPSEC
    589 	if (!ipsec_getnhist(m))
    590 #else
    591 	if (1)
    592 #endif
    593 	{
    594 		struct in_addr odst;
    595 
    596 		odst = ip->ip_dst;
    597 		if (pfil_run_hooks(&inet_pfil_hook, &m, m->m_pkthdr.rcvif,
    598 		    PFIL_IN) != 0)
    599 			return;
    600 		if (m == NULL)
    601 			return;
    602 		ip = mtod(m, struct ip *);
    603 		hlen = ip->ip_hl << 2;
    604 		srcrt = (odst.s_addr != ip->ip_dst.s_addr);
    605 	}
    606 #endif /* PFIL_HOOKS */
    607 
    608 #ifdef ALTQ
    609 	/* XXX Temporary until ALTQ is changed to use a pfil hook */
    610 	if (altq_input != NULL && (*altq_input)(m, AF_INET) == 0) {
    611 		/* packet dropped by traffic conditioner */
    612 		return;
    613 	}
    614 #endif
    615 
    616 	/*
    617 	 * Process options and, if not destined for us,
    618 	 * ship it on.  ip_dooptions returns 1 when an
    619 	 * error was detected (causing an icmp message
    620 	 * to be sent and the original packet to be freed).
    621 	 */
    622 	ip_nhops = 0;		/* for source routed packets */
    623 	if (hlen > sizeof (struct ip) && ip_dooptions(m))
    624 		return;
    625 
    626 	/*
    627 	 * Enable a consistency check between the destination address
    628 	 * and the arrival interface for a unicast packet (the RFC 1122
    629 	 * strong ES model) if IP forwarding is disabled and the packet
    630 	 * is not locally generated.
    631 	 *
    632 	 * XXX - Checking also should be disabled if the destination
    633 	 * address is ipnat'ed to a different interface.
    634 	 *
    635 	 * XXX - Checking is incompatible with IP aliases added
    636 	 * to the loopback interface instead of the interface where
    637 	 * the packets are received.
    638 	 *
    639 	 * XXX - We need to add a per ifaddr flag for this so that
    640 	 * we get finer grain control.
    641 	 */
    642 	checkif = ip_checkinterface && (ipforwarding == 0) &&
    643 	    (m->m_pkthdr.rcvif != NULL) &&
    644 	    ((m->m_pkthdr.rcvif->if_flags & IFF_LOOPBACK) == 0);
    645 
    646 	/*
    647 	 * Check our list of addresses, to see if the packet is for us.
    648 	 *
    649 	 * Traditional 4.4BSD did not consult IFF_UP at all.
    650 	 * The behavior here is to treat addresses on !IFF_UP interface
    651 	 * as not mine.
    652 	 */
    653 	downmatch = 0;
    654 	LIST_FOREACH(ia, &IN_IFADDR_HASH(ip->ip_dst.s_addr), ia_hash) {
    655 		if (in_hosteq(ia->ia_addr.sin_addr, ip->ip_dst)) {
    656 			if (checkif && ia->ia_ifp != m->m_pkthdr.rcvif)
    657 				continue;
    658 			if ((ia->ia_ifp->if_flags & IFF_UP) != 0)
    659 				break;
    660 			else
    661 				downmatch++;
    662 		}
    663 	}
    664 	if (ia != NULL)
    665 		goto ours;
    666 	if (m->m_pkthdr.rcvif->if_flags & IFF_BROADCAST) {
    667 		TAILQ_FOREACH(ifa, &m->m_pkthdr.rcvif->if_addrlist, ifa_list) {
    668 			if (ifa->ifa_addr->sa_family != AF_INET)
    669 				continue;
    670 			ia = ifatoia(ifa);
    671 			if (in_hosteq(ip->ip_dst, ia->ia_broadaddr.sin_addr) ||
    672 			    in_hosteq(ip->ip_dst, ia->ia_netbroadcast) ||
    673 			    /*
    674 			     * Look for all-0's host part (old broadcast addr),
    675 			     * either for subnet or net.
    676 			     */
    677 			    ip->ip_dst.s_addr == ia->ia_subnet ||
    678 			    ip->ip_dst.s_addr == ia->ia_net)
    679 				goto ours;
    680 			/*
    681 			 * An interface with IP address zero accepts
    682 			 * all packets that arrive on that interface.
    683 			 */
    684 			if (in_nullhost(ia->ia_addr.sin_addr))
    685 				goto ours;
    686 		}
    687 	}
    688 	if (IN_MULTICAST(ip->ip_dst.s_addr)) {
    689 		struct in_multi *inm;
    690 #ifdef MROUTING
    691 		extern struct socket *ip_mrouter;
    692 
    693 		if (M_READONLY(m)) {
    694 			if ((m = m_pullup(m, hlen)) == 0) {
    695 				ipstat.ips_toosmall++;
    696 				return;
    697 			}
    698 			ip = mtod(m, struct ip *);
    699 		}
    700 
    701 		if (ip_mrouter) {
    702 			/*
    703 			 * If we are acting as a multicast router, all
    704 			 * incoming multicast packets are passed to the
    705 			 * kernel-level multicast forwarding function.
    706 			 * The packet is returned (relatively) intact; if
    707 			 * ip_mforward() returns a non-zero value, the packet
    708 			 * must be discarded, else it may be accepted below.
    709 			 *
    710 			 * (The IP ident field is put in the same byte order
    711 			 * as expected when ip_mforward() is called from
    712 			 * ip_output().)
    713 			 */
    714 			if (ip_mforward(m, m->m_pkthdr.rcvif) != 0) {
    715 				ipstat.ips_cantforward++;
    716 				m_freem(m);
    717 				return;
    718 			}
    719 
    720 			/*
    721 			 * The process-level routing demon needs to receive
    722 			 * all multicast IGMP packets, whether or not this
    723 			 * host belongs to their destination groups.
    724 			 */
    725 			if (ip->ip_p == IPPROTO_IGMP)
    726 				goto ours;
    727 			ipstat.ips_forward++;
    728 		}
    729 #endif
    730 		/*
    731 		 * See if we belong to the destination multicast group on the
    732 		 * arrival interface.
    733 		 */
    734 		IN_LOOKUP_MULTI(ip->ip_dst, m->m_pkthdr.rcvif, inm);
    735 		if (inm == NULL) {
    736 			ipstat.ips_cantforward++;
    737 			m_freem(m);
    738 			return;
    739 		}
    740 		goto ours;
    741 	}
    742 	if (ip->ip_dst.s_addr == INADDR_BROADCAST ||
    743 	    in_nullhost(ip->ip_dst))
    744 		goto ours;
    745 
    746 	/*
    747 	 * Not for us; forward if possible and desirable.
    748 	 */
    749 	if (ipforwarding == 0) {
    750 		ipstat.ips_cantforward++;
    751 		m_freem(m);
    752 	} else {
    753 		/*
    754 		 * If ip_dst matched any of my address on !IFF_UP interface,
    755 		 * and there's no IFF_UP interface that matches ip_dst,
    756 		 * send icmp unreach.  Forwarding it will result in in-kernel
    757 		 * forwarding loop till TTL goes to 0.
    758 		 */
    759 		if (downmatch) {
    760 			icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, 0, 0);
    761 			ipstat.ips_cantforward++;
    762 			return;
    763 		}
    764 #ifdef IPSEC
    765 		if (ipsec4_in_reject(m, NULL)) {
    766 			ipsecstat.in_polvio++;
    767 			goto bad;
    768 		}
    769 #endif
    770 
    771 		ip_forward(m, srcrt);
    772 	}
    773 	return;
    774 
    775 ours:
    776 	/*
    777 	 * If offset or IP_MF are set, must reassemble.
    778 	 * Otherwise, nothing need be done.
    779 	 * (We could look in the reassembly queue to see
    780 	 * if the packet was previously fragmented,
    781 	 * but it's not worth the time; just let them time out.)
    782 	 */
    783 	if (ip->ip_off & ~htons(IP_DF|IP_RF)) {
    784 		if (M_READONLY(m)) {
    785 			if ((m = m_pullup(m, hlen)) == NULL) {
    786 				ipstat.ips_toosmall++;
    787 				goto bad;
    788 			}
    789 			ip = mtod(m, struct ip *);
    790 		}
    791 
    792 		/*
    793 		 * Look for queue of fragments
    794 		 * of this datagram.
    795 		 */
    796 		IPQ_LOCK();
    797 		LIST_FOREACH(fp, &ipq, ipq_q)
    798 			if (ip->ip_id == fp->ipq_id &&
    799 			    in_hosteq(ip->ip_src, fp->ipq_src) &&
    800 			    in_hosteq(ip->ip_dst, fp->ipq_dst) &&
    801 			    ip->ip_p == fp->ipq_p)
    802 				goto found;
    803 		fp = 0;
    804 found:
    805 
    806 		/*
    807 		 * Adjust ip_len to not reflect header,
    808 		 * set ipqe_mff if more fragments are expected,
    809 		 * convert offset of this to bytes.
    810 		 */
    811 		ip->ip_len = htons(ntohs(ip->ip_len) - hlen);
    812 		mff = (ip->ip_off & htons(IP_MF)) != 0;
    813 		if (mff) {
    814 		        /*
    815 		         * Make sure that fragments have a data length
    816 			 * that's a non-zero multiple of 8 bytes.
    817 		         */
    818 			if (ntohs(ip->ip_len) == 0 ||
    819 			    (ntohs(ip->ip_len) & 0x7) != 0) {
    820 				ipstat.ips_badfrags++;
    821 				IPQ_UNLOCK();
    822 				goto bad;
    823 			}
    824 		}
    825 		ip->ip_off = htons((ntohs(ip->ip_off) & IP_OFFMASK) << 3);
    826 
    827 		/*
    828 		 * If datagram marked as having more fragments
    829 		 * or if this is not the first fragment,
    830 		 * attempt reassembly; if it succeeds, proceed.
    831 		 */
    832 		if (mff || ip->ip_off != htons(0)) {
    833 			ipstat.ips_fragments++;
    834 			ipqe = pool_get(&ipqent_pool, PR_NOWAIT);
    835 			if (ipqe == NULL) {
    836 				ipstat.ips_rcvmemdrop++;
    837 				IPQ_UNLOCK();
    838 				goto bad;
    839 			}
    840 			ipqe->ipqe_mff = mff;
    841 			ipqe->ipqe_m = m;
    842 			ipqe->ipqe_ip = ip;
    843 			m = ip_reass(ipqe, fp);
    844 			if (m == 0) {
    845 				IPQ_UNLOCK();
    846 				return;
    847 			}
    848 			ipstat.ips_reassembled++;
    849 			ip = mtod(m, struct ip *);
    850 			hlen = ip->ip_hl << 2;
    851 			ip->ip_len = htons(ntohs(ip->ip_len) + hlen);
    852 		} else
    853 			if (fp)
    854 				ip_freef(fp);
    855 		IPQ_UNLOCK();
    856 	}
    857 
    858 #ifdef IPSEC
    859 	/*
    860 	 * enforce IPsec policy checking if we are seeing last header.
    861 	 * note that we do not visit this with protocols with pcb layer
    862 	 * code - like udp/tcp/raw ip.
    863 	 */
    864 	if ((inetsw[ip_protox[ip->ip_p]].pr_flags & PR_LASTHDR) != 0 &&
    865 	    ipsec4_in_reject(m, NULL)) {
    866 		ipsecstat.in_polvio++;
    867 		goto bad;
    868 	}
    869 #endif
    870 
    871 	/*
    872 	 * Switch out to protocol's input routine.
    873 	 */
    874 #if IFA_STATS
    875 	if (ia && ip)
    876 		ia->ia_ifa.ifa_data.ifad_inbytes += ntohs(ip->ip_len);
    877 #endif
    878 	ipstat.ips_delivered++;
    879     {
    880 	int off = hlen, nh = ip->ip_p;
    881 
    882 	(*inetsw[ip_protox[nh]].pr_input)(m, off, nh);
    883 	return;
    884     }
    885 bad:
    886 	m_freem(m);
    887 	return;
    888 
    889 badcsum:
    890 	ipstat.ips_badsum++;
    891 	m_freem(m);
    892 }
    893 
    894 /*
    895  * Take incoming datagram fragment and try to
    896  * reassemble it into whole datagram.  If a chain for
    897  * reassembly of this datagram already exists, then it
    898  * is given as fp; otherwise have to make a chain.
    899  */
    900 struct mbuf *
    901 ip_reass(ipqe, fp)
    902 	struct ipqent *ipqe;
    903 	struct ipq *fp;
    904 {
    905 	struct mbuf *m = ipqe->ipqe_m;
    906 	struct ipqent *nq, *p, *q;
    907 	struct ip *ip;
    908 	struct mbuf *t;
    909 	int hlen = ipqe->ipqe_ip->ip_hl << 2;
    910 	int i, next;
    911 
    912 	IPQ_LOCK_CHECK();
    913 
    914 	/*
    915 	 * Presence of header sizes in mbufs
    916 	 * would confuse code below.
    917 	 */
    918 	m->m_data += hlen;
    919 	m->m_len -= hlen;
    920 
    921 	/*
    922 	 * If first fragment to arrive, create a reassembly queue.
    923 	 */
    924 	if (fp == 0) {
    925 		/*
    926 		 * Enforce upper bound on number of fragmented packets
    927 		 * for which we attempt reassembly;
    928 		 * If maxfrag is 0, never accept fragments.
    929 		 * If maxfrag is -1, accept all fragments without limitation.
    930 		 */
    931 		if (ip_maxfragpackets < 0)
    932 			;
    933 		else if (ip_nfragpackets >= ip_maxfragpackets)
    934 			goto dropfrag;
    935 		ip_nfragpackets++;
    936 		MALLOC(fp, struct ipq *, sizeof (struct ipq),
    937 		    M_FTABLE, M_NOWAIT);
    938 		if (fp == NULL)
    939 			goto dropfrag;
    940 		LIST_INSERT_HEAD(&ipq, fp, ipq_q);
    941 		fp->ipq_ttl = IPFRAGTTL;
    942 		fp->ipq_p = ipqe->ipqe_ip->ip_p;
    943 		fp->ipq_id = ipqe->ipqe_ip->ip_id;
    944 		TAILQ_INIT(&fp->ipq_fragq);
    945 		fp->ipq_src = ipqe->ipqe_ip->ip_src;
    946 		fp->ipq_dst = ipqe->ipqe_ip->ip_dst;
    947 		p = NULL;
    948 		goto insert;
    949 	}
    950 
    951 	/*
    952 	 * Find a segment which begins after this one does.
    953 	 */
    954 	for (p = NULL, q = TAILQ_FIRST(&fp->ipq_fragq); q != NULL;
    955 	    p = q, q = TAILQ_NEXT(q, ipqe_q))
    956 		if (ntohs(q->ipqe_ip->ip_off) > ntohs(ipqe->ipqe_ip->ip_off))
    957 			break;
    958 
    959 	/*
    960 	 * If there is a preceding segment, it may provide some of
    961 	 * our data already.  If so, drop the data from the incoming
    962 	 * segment.  If it provides all of our data, drop us.
    963 	 */
    964 	if (p != NULL) {
    965 		i = ntohs(p->ipqe_ip->ip_off) + ntohs(p->ipqe_ip->ip_len) -
    966 		    ntohs(ipqe->ipqe_ip->ip_off);
    967 		if (i > 0) {
    968 			if (i >= ntohs(ipqe->ipqe_ip->ip_len))
    969 				goto dropfrag;
    970 			m_adj(ipqe->ipqe_m, i);
    971 			ipqe->ipqe_ip->ip_off =
    972 			    htons(ntohs(ipqe->ipqe_ip->ip_off) + i);
    973 			ipqe->ipqe_ip->ip_len =
    974 			    htons(ntohs(ipqe->ipqe_ip->ip_len) - i);
    975 		}
    976 	}
    977 
    978 	/*
    979 	 * While we overlap succeeding segments trim them or,
    980 	 * if they are completely covered, dequeue them.
    981 	 */
    982 	for (; q != NULL &&
    983 	    ntohs(ipqe->ipqe_ip->ip_off) + ntohs(ipqe->ipqe_ip->ip_len) >
    984 	    ntohs(q->ipqe_ip->ip_off); q = nq) {
    985 		i = (ntohs(ipqe->ipqe_ip->ip_off) +
    986 		    ntohs(ipqe->ipqe_ip->ip_len)) - ntohs(q->ipqe_ip->ip_off);
    987 		if (i < ntohs(q->ipqe_ip->ip_len)) {
    988 			q->ipqe_ip->ip_len =
    989 			    htons(ntohs(q->ipqe_ip->ip_len) - i);
    990 			q->ipqe_ip->ip_off =
    991 			    htons(ntohs(q->ipqe_ip->ip_off) + i);
    992 			m_adj(q->ipqe_m, i);
    993 			break;
    994 		}
    995 		nq = TAILQ_NEXT(q, ipqe_q);
    996 		m_freem(q->ipqe_m);
    997 		TAILQ_REMOVE(&fp->ipq_fragq, q, ipqe_q);
    998 		pool_put(&ipqent_pool, q);
    999 	}
   1000 
   1001 insert:
   1002 	/*
   1003 	 * Stick new segment in its place;
   1004 	 * check for complete reassembly.
   1005 	 */
   1006 	if (p == NULL) {
   1007 		TAILQ_INSERT_HEAD(&fp->ipq_fragq, ipqe, ipqe_q);
   1008 	} else {
   1009 		TAILQ_INSERT_AFTER(&fp->ipq_fragq, p, ipqe, ipqe_q);
   1010 	}
   1011 	next = 0;
   1012 	for (p = NULL, q = TAILQ_FIRST(&fp->ipq_fragq); q != NULL;
   1013 	    p = q, q = TAILQ_NEXT(q, ipqe_q)) {
   1014 		if (ntohs(q->ipqe_ip->ip_off) != next)
   1015 			return (0);
   1016 		next += ntohs(q->ipqe_ip->ip_len);
   1017 	}
   1018 	if (p->ipqe_mff)
   1019 		return (0);
   1020 
   1021 	/*
   1022 	 * Reassembly is complete.  Check for a bogus message size and
   1023 	 * concatenate fragments.
   1024 	 */
   1025 	q = TAILQ_FIRST(&fp->ipq_fragq);
   1026 	ip = q->ipqe_ip;
   1027 	if ((next + (ip->ip_hl << 2)) > IP_MAXPACKET) {
   1028 		ipstat.ips_toolong++;
   1029 		ip_freef(fp);
   1030 		return (0);
   1031 	}
   1032 	m = q->ipqe_m;
   1033 	t = m->m_next;
   1034 	m->m_next = 0;
   1035 	m_cat(m, t);
   1036 	nq = TAILQ_NEXT(q, ipqe_q);
   1037 	pool_put(&ipqent_pool, q);
   1038 	for (q = nq; q != NULL; q = nq) {
   1039 		t = q->ipqe_m;
   1040 		nq = TAILQ_NEXT(q, ipqe_q);
   1041 		pool_put(&ipqent_pool, q);
   1042 		m_cat(m, t);
   1043 	}
   1044 
   1045 	/*
   1046 	 * Create header for new ip packet by
   1047 	 * modifying header of first packet;
   1048 	 * dequeue and discard fragment reassembly header.
   1049 	 * Make header visible.
   1050 	 */
   1051 	ip->ip_len = htons(next);
   1052 	ip->ip_src = fp->ipq_src;
   1053 	ip->ip_dst = fp->ipq_dst;
   1054 	LIST_REMOVE(fp, ipq_q);
   1055 	FREE(fp, M_FTABLE);
   1056 	ip_nfragpackets--;
   1057 	m->m_len += (ip->ip_hl << 2);
   1058 	m->m_data -= (ip->ip_hl << 2);
   1059 	/* some debugging cruft by sklower, below, will go away soon */
   1060 	if (m->m_flags & M_PKTHDR) { /* XXX this should be done elsewhere */
   1061 		int plen = 0;
   1062 		for (t = m; t; t = t->m_next)
   1063 			plen += t->m_len;
   1064 		m->m_pkthdr.len = plen;
   1065 	}
   1066 	return (m);
   1067 
   1068 dropfrag:
   1069 	ipstat.ips_fragdropped++;
   1070 	m_freem(m);
   1071 	pool_put(&ipqent_pool, ipqe);
   1072 	return (0);
   1073 }
   1074 
   1075 /*
   1076  * Free a fragment reassembly header and all
   1077  * associated datagrams.
   1078  */
   1079 void
   1080 ip_freef(fp)
   1081 	struct ipq *fp;
   1082 {
   1083 	struct ipqent *q, *p;
   1084 
   1085 	IPQ_LOCK_CHECK();
   1086 
   1087 	for (q = TAILQ_FIRST(&fp->ipq_fragq); q != NULL; q = p) {
   1088 		p = TAILQ_NEXT(q, ipqe_q);
   1089 		m_freem(q->ipqe_m);
   1090 		TAILQ_REMOVE(&fp->ipq_fragq, q, ipqe_q);
   1091 		pool_put(&ipqent_pool, q);
   1092 	}
   1093 	LIST_REMOVE(fp, ipq_q);
   1094 	FREE(fp, M_FTABLE);
   1095 	ip_nfragpackets--;
   1096 }
   1097 
   1098 /*
   1099  * IP timer processing;
   1100  * if a timer expires on a reassembly
   1101  * queue, discard it.
   1102  */
   1103 void
   1104 ip_slowtimo()
   1105 {
   1106 	struct ipq *fp, *nfp;
   1107 	int s = splsoftnet();
   1108 
   1109 	IPQ_LOCK();
   1110 	for (fp = LIST_FIRST(&ipq); fp != NULL; fp = nfp) {
   1111 		nfp = LIST_NEXT(fp, ipq_q);
   1112 		if (--fp->ipq_ttl == 0) {
   1113 			ipstat.ips_fragtimeout++;
   1114 			ip_freef(fp);
   1115 		}
   1116 	}
   1117 	/*
   1118 	 * If we are over the maximum number of fragments
   1119 	 * (due to the limit being lowered), drain off
   1120 	 * enough to get down to the new limit.
   1121 	 */
   1122 	if (ip_maxfragpackets < 0)
   1123 		;
   1124 	else {
   1125 		while (ip_nfragpackets > ip_maxfragpackets && LIST_FIRST(&ipq))
   1126 			ip_freef(LIST_FIRST(&ipq));
   1127 	}
   1128 	IPQ_UNLOCK();
   1129 #ifdef GATEWAY
   1130 	ipflow_slowtimo();
   1131 #endif
   1132 	splx(s);
   1133 }
   1134 
   1135 /*
   1136  * Drain off all datagram fragments.
   1137  */
   1138 void
   1139 ip_drain()
   1140 {
   1141 
   1142 	/*
   1143 	 * We may be called from a device's interrupt context.  If
   1144 	 * the ipq is already busy, just bail out now.
   1145 	 */
   1146 	if (ipq_lock_try() == 0)
   1147 		return;
   1148 
   1149 	while (LIST_FIRST(&ipq) != NULL) {
   1150 		ipstat.ips_fragdropped++;
   1151 		ip_freef(LIST_FIRST(&ipq));
   1152 	}
   1153 
   1154 	IPQ_UNLOCK();
   1155 }
   1156 
   1157 /*
   1158  * Do option processing on a datagram,
   1159  * possibly discarding it if bad options are encountered,
   1160  * or forwarding it if source-routed.
   1161  * Returns 1 if packet has been forwarded/freed,
   1162  * 0 if the packet should be processed further.
   1163  */
   1164 int
   1165 ip_dooptions(m)
   1166 	struct mbuf *m;
   1167 {
   1168 	struct ip *ip = mtod(m, struct ip *);
   1169 	u_char *cp, *cp0;
   1170 	struct ip_timestamp *ipt;
   1171 	struct in_ifaddr *ia;
   1172 	int opt, optlen, cnt, off, code, type = ICMP_PARAMPROB, forward = 0;
   1173 	struct in_addr dst;
   1174 	n_time ntime;
   1175 
   1176 	dst = ip->ip_dst;
   1177 	cp = (u_char *)(ip + 1);
   1178 	cnt = (ip->ip_hl << 2) - sizeof (struct ip);
   1179 	for (; cnt > 0; cnt -= optlen, cp += optlen) {
   1180 		opt = cp[IPOPT_OPTVAL];
   1181 		if (opt == IPOPT_EOL)
   1182 			break;
   1183 		if (opt == IPOPT_NOP)
   1184 			optlen = 1;
   1185 		else {
   1186 			if (cnt < IPOPT_OLEN + sizeof(*cp)) {
   1187 				code = &cp[IPOPT_OLEN] - (u_char *)ip;
   1188 				goto bad;
   1189 			}
   1190 			optlen = cp[IPOPT_OLEN];
   1191 			if (optlen < IPOPT_OLEN + sizeof(*cp) || optlen > cnt) {
   1192 				code = &cp[IPOPT_OLEN] - (u_char *)ip;
   1193 				goto bad;
   1194 			}
   1195 		}
   1196 		switch (opt) {
   1197 
   1198 		default:
   1199 			break;
   1200 
   1201 		/*
   1202 		 * Source routing with record.
   1203 		 * Find interface with current destination address.
   1204 		 * If none on this machine then drop if strictly routed,
   1205 		 * or do nothing if loosely routed.
   1206 		 * Record interface address and bring up next address
   1207 		 * component.  If strictly routed make sure next
   1208 		 * address is on directly accessible net.
   1209 		 */
   1210 		case IPOPT_LSRR:
   1211 		case IPOPT_SSRR:
   1212 			if (ip_allowsrcrt == 0) {
   1213 				type = ICMP_UNREACH;
   1214 				code = ICMP_UNREACH_NET_PROHIB;
   1215 				goto bad;
   1216 			}
   1217 			if (optlen < IPOPT_OFFSET + sizeof(*cp)) {
   1218 				code = &cp[IPOPT_OLEN] - (u_char *)ip;
   1219 				goto bad;
   1220 			}
   1221 			if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
   1222 				code = &cp[IPOPT_OFFSET] - (u_char *)ip;
   1223 				goto bad;
   1224 			}
   1225 			ipaddr.sin_addr = ip->ip_dst;
   1226 			ia = ifatoia(ifa_ifwithaddr(sintosa(&ipaddr)));
   1227 			if (ia == 0) {
   1228 				if (opt == IPOPT_SSRR) {
   1229 					type = ICMP_UNREACH;
   1230 					code = ICMP_UNREACH_SRCFAIL;
   1231 					goto bad;
   1232 				}
   1233 				/*
   1234 				 * Loose routing, and not at next destination
   1235 				 * yet; nothing to do except forward.
   1236 				 */
   1237 				break;
   1238 			}
   1239 			off--;			/* 0 origin */
   1240 			if ((off + sizeof(struct in_addr)) > optlen) {
   1241 				/*
   1242 				 * End of source route.  Should be for us.
   1243 				 */
   1244 				save_rte(cp, ip->ip_src);
   1245 				break;
   1246 			}
   1247 			/*
   1248 			 * locate outgoing interface
   1249 			 */
   1250 			bcopy((caddr_t)(cp + off), (caddr_t)&ipaddr.sin_addr,
   1251 			    sizeof(ipaddr.sin_addr));
   1252 			if (opt == IPOPT_SSRR)
   1253 				ia = ifatoia(ifa_ifwithaddr(sintosa(&ipaddr)));
   1254 			else
   1255 				ia = ip_rtaddr(ipaddr.sin_addr);
   1256 			if (ia == 0) {
   1257 				type = ICMP_UNREACH;
   1258 				code = ICMP_UNREACH_SRCFAIL;
   1259 				goto bad;
   1260 			}
   1261 			ip->ip_dst = ipaddr.sin_addr;
   1262 			bcopy((caddr_t)&ia->ia_addr.sin_addr,
   1263 			    (caddr_t)(cp + off), sizeof(struct in_addr));
   1264 			cp[IPOPT_OFFSET] += sizeof(struct in_addr);
   1265 			/*
   1266 			 * Let ip_intr's mcast routing check handle mcast pkts
   1267 			 */
   1268 			forward = !IN_MULTICAST(ip->ip_dst.s_addr);
   1269 			break;
   1270 
   1271 		case IPOPT_RR:
   1272 			if (optlen < IPOPT_OFFSET + sizeof(*cp)) {
   1273 				code = &cp[IPOPT_OLEN] - (u_char *)ip;
   1274 				goto bad;
   1275 			}
   1276 			if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
   1277 				code = &cp[IPOPT_OFFSET] - (u_char *)ip;
   1278 				goto bad;
   1279 			}
   1280 			/*
   1281 			 * If no space remains, ignore.
   1282 			 */
   1283 			off--;			/* 0 origin */
   1284 			if ((off + sizeof(struct in_addr)) > optlen)
   1285 				break;
   1286 			bcopy((caddr_t)(&ip->ip_dst), (caddr_t)&ipaddr.sin_addr,
   1287 			    sizeof(ipaddr.sin_addr));
   1288 			/*
   1289 			 * locate outgoing interface; if we're the destination,
   1290 			 * use the incoming interface (should be same).
   1291 			 */
   1292 			if ((ia = ifatoia(ifa_ifwithaddr(sintosa(&ipaddr))))
   1293 			    == NULL &&
   1294 			    (ia = ip_rtaddr(ipaddr.sin_addr)) == NULL) {
   1295 				type = ICMP_UNREACH;
   1296 				code = ICMP_UNREACH_HOST;
   1297 				goto bad;
   1298 			}
   1299 			bcopy((caddr_t)&ia->ia_addr.sin_addr,
   1300 			    (caddr_t)(cp + off), sizeof(struct in_addr));
   1301 			cp[IPOPT_OFFSET] += sizeof(struct in_addr);
   1302 			break;
   1303 
   1304 		case IPOPT_TS:
   1305 			code = cp - (u_char *)ip;
   1306 			ipt = (struct ip_timestamp *)cp;
   1307 			if (ipt->ipt_len < 4 || ipt->ipt_len > 40) {
   1308 				code = (u_char *)&ipt->ipt_len - (u_char *)ip;
   1309 				goto bad;
   1310 			}
   1311 			if (ipt->ipt_ptr < 5) {
   1312 				code = (u_char *)&ipt->ipt_ptr - (u_char *)ip;
   1313 				goto bad;
   1314 			}
   1315 			if (ipt->ipt_ptr > ipt->ipt_len - sizeof (int32_t)) {
   1316 				if (++ipt->ipt_oflw == 0) {
   1317 					code = (u_char *)&ipt->ipt_ptr -
   1318 					    (u_char *)ip;
   1319 					goto bad;
   1320 				}
   1321 				break;
   1322 			}
   1323 			cp0 = (cp + ipt->ipt_ptr - 1);
   1324 			switch (ipt->ipt_flg) {
   1325 
   1326 			case IPOPT_TS_TSONLY:
   1327 				break;
   1328 
   1329 			case IPOPT_TS_TSANDADDR:
   1330 				if (ipt->ipt_ptr - 1 + sizeof(n_time) +
   1331 				    sizeof(struct in_addr) > ipt->ipt_len) {
   1332 					code = (u_char *)&ipt->ipt_ptr -
   1333 					    (u_char *)ip;
   1334 					goto bad;
   1335 				}
   1336 				ipaddr.sin_addr = dst;
   1337 				ia = ifatoia(ifaof_ifpforaddr(sintosa(&ipaddr),
   1338 				    m->m_pkthdr.rcvif));
   1339 				if (ia == 0)
   1340 					continue;
   1341 				bcopy(&ia->ia_addr.sin_addr,
   1342 				    cp0, sizeof(struct in_addr));
   1343 				ipt->ipt_ptr += sizeof(struct in_addr);
   1344 				break;
   1345 
   1346 			case IPOPT_TS_PRESPEC:
   1347 				if (ipt->ipt_ptr - 1 + sizeof(n_time) +
   1348 				    sizeof(struct in_addr) > ipt->ipt_len) {
   1349 					code = (u_char *)&ipt->ipt_ptr -
   1350 					    (u_char *)ip;
   1351 					goto bad;
   1352 				}
   1353 				bcopy(cp0, &ipaddr.sin_addr,
   1354 				    sizeof(struct in_addr));
   1355 				if (ifatoia(ifa_ifwithaddr(sintosa(&ipaddr)))
   1356 				    == NULL)
   1357 					continue;
   1358 				ipt->ipt_ptr += sizeof(struct in_addr);
   1359 				break;
   1360 
   1361 			default:
   1362 				/* XXX can't take &ipt->ipt_flg */
   1363 				code = (u_char *)&ipt->ipt_ptr -
   1364 				    (u_char *)ip + 1;
   1365 				goto bad;
   1366 			}
   1367 			ntime = iptime();
   1368 			cp0 = (u_char *) &ntime; /* XXX grumble, GCC... */
   1369 			bcopy(cp0, (caddr_t)cp + ipt->ipt_ptr - 1,
   1370 			    sizeof(n_time));
   1371 			ipt->ipt_ptr += sizeof(n_time);
   1372 		}
   1373 	}
   1374 	if (forward) {
   1375 		if (ip_forwsrcrt == 0) {
   1376 			type = ICMP_UNREACH;
   1377 			code = ICMP_UNREACH_SRCFAIL;
   1378 			goto bad;
   1379 		}
   1380 		ip_forward(m, 1);
   1381 		return (1);
   1382 	}
   1383 	return (0);
   1384 bad:
   1385 	icmp_error(m, type, code, 0, 0);
   1386 	ipstat.ips_badoptions++;
   1387 	return (1);
   1388 }
   1389 
   1390 /*
   1391  * Given address of next destination (final or next hop),
   1392  * return internet address info of interface to be used to get there.
   1393  */
   1394 struct in_ifaddr *
   1395 ip_rtaddr(dst)
   1396 	 struct in_addr dst;
   1397 {
   1398 	struct sockaddr_in *sin;
   1399 
   1400 	sin = satosin(&ipforward_rt.ro_dst);
   1401 
   1402 	if (ipforward_rt.ro_rt == 0 || !in_hosteq(dst, sin->sin_addr)) {
   1403 		if (ipforward_rt.ro_rt) {
   1404 			RTFREE(ipforward_rt.ro_rt);
   1405 			ipforward_rt.ro_rt = 0;
   1406 		}
   1407 		sin->sin_family = AF_INET;
   1408 		sin->sin_len = sizeof(*sin);
   1409 		sin->sin_addr = dst;
   1410 
   1411 		rtalloc(&ipforward_rt);
   1412 	}
   1413 	if (ipforward_rt.ro_rt == 0)
   1414 		return ((struct in_ifaddr *)0);
   1415 	return (ifatoia(ipforward_rt.ro_rt->rt_ifa));
   1416 }
   1417 
   1418 /*
   1419  * Save incoming source route for use in replies,
   1420  * to be picked up later by ip_srcroute if the receiver is interested.
   1421  */
   1422 void
   1423 save_rte(option, dst)
   1424 	u_char *option;
   1425 	struct in_addr dst;
   1426 {
   1427 	unsigned olen;
   1428 
   1429 	olen = option[IPOPT_OLEN];
   1430 #ifdef DIAGNOSTIC
   1431 	if (ipprintfs)
   1432 		printf("save_rte: olen %d\n", olen);
   1433 #endif /* 0 */
   1434 	if (olen > sizeof(ip_srcrt) - (1 + sizeof(dst)))
   1435 		return;
   1436 	bcopy((caddr_t)option, (caddr_t)ip_srcrt.srcopt, olen);
   1437 	ip_nhops = (olen - IPOPT_OFFSET - 1) / sizeof(struct in_addr);
   1438 	ip_srcrt.dst = dst;
   1439 }
   1440 
   1441 /*
   1442  * Retrieve incoming source route for use in replies,
   1443  * in the same form used by setsockopt.
   1444  * The first hop is placed before the options, will be removed later.
   1445  */
   1446 struct mbuf *
   1447 ip_srcroute()
   1448 {
   1449 	struct in_addr *p, *q;
   1450 	struct mbuf *m;
   1451 
   1452 	if (ip_nhops == 0)
   1453 		return ((struct mbuf *)0);
   1454 	m = m_get(M_DONTWAIT, MT_SOOPTS);
   1455 	if (m == 0)
   1456 		return ((struct mbuf *)0);
   1457 
   1458 	MCLAIM(m, &inetdomain.dom_mowner);
   1459 #define OPTSIZ	(sizeof(ip_srcrt.nop) + sizeof(ip_srcrt.srcopt))
   1460 
   1461 	/* length is (nhops+1)*sizeof(addr) + sizeof(nop + srcrt header) */
   1462 	m->m_len = ip_nhops * sizeof(struct in_addr) + sizeof(struct in_addr) +
   1463 	    OPTSIZ;
   1464 #ifdef DIAGNOSTIC
   1465 	if (ipprintfs)
   1466 		printf("ip_srcroute: nhops %d mlen %d", ip_nhops, m->m_len);
   1467 #endif
   1468 
   1469 	/*
   1470 	 * First save first hop for return route
   1471 	 */
   1472 	p = &ip_srcrt.route[ip_nhops - 1];
   1473 	*(mtod(m, struct in_addr *)) = *p--;
   1474 #ifdef DIAGNOSTIC
   1475 	if (ipprintfs)
   1476 		printf(" hops %x", ntohl(mtod(m, struct in_addr *)->s_addr));
   1477 #endif
   1478 
   1479 	/*
   1480 	 * Copy option fields and padding (nop) to mbuf.
   1481 	 */
   1482 	ip_srcrt.nop = IPOPT_NOP;
   1483 	ip_srcrt.srcopt[IPOPT_OFFSET] = IPOPT_MINOFF;
   1484 	bcopy((caddr_t)&ip_srcrt.nop,
   1485 	    mtod(m, caddr_t) + sizeof(struct in_addr), OPTSIZ);
   1486 	q = (struct in_addr *)(mtod(m, caddr_t) +
   1487 	    sizeof(struct in_addr) + OPTSIZ);
   1488 #undef OPTSIZ
   1489 	/*
   1490 	 * Record return path as an IP source route,
   1491 	 * reversing the path (pointers are now aligned).
   1492 	 */
   1493 	while (p >= ip_srcrt.route) {
   1494 #ifdef DIAGNOSTIC
   1495 		if (ipprintfs)
   1496 			printf(" %x", ntohl(q->s_addr));
   1497 #endif
   1498 		*q++ = *p--;
   1499 	}
   1500 	/*
   1501 	 * Last hop goes to final destination.
   1502 	 */
   1503 	*q = ip_srcrt.dst;
   1504 #ifdef DIAGNOSTIC
   1505 	if (ipprintfs)
   1506 		printf(" %x\n", ntohl(q->s_addr));
   1507 #endif
   1508 	return (m);
   1509 }
   1510 
   1511 /*
   1512  * Strip out IP options, at higher
   1513  * level protocol in the kernel.
   1514  * Second argument is buffer to which options
   1515  * will be moved, and return value is their length.
   1516  * XXX should be deleted; last arg currently ignored.
   1517  */
   1518 void
   1519 ip_stripoptions(m, mopt)
   1520 	struct mbuf *m;
   1521 	struct mbuf *mopt;
   1522 {
   1523 	int i;
   1524 	struct ip *ip = mtod(m, struct ip *);
   1525 	caddr_t opts;
   1526 	int olen;
   1527 
   1528 	olen = (ip->ip_hl << 2) - sizeof (struct ip);
   1529 	opts = (caddr_t)(ip + 1);
   1530 	i = m->m_len - (sizeof (struct ip) + olen);
   1531 	bcopy(opts  + olen, opts, (unsigned)i);
   1532 	m->m_len -= olen;
   1533 	if (m->m_flags & M_PKTHDR)
   1534 		m->m_pkthdr.len -= olen;
   1535 	ip->ip_len = htons(ntohs(ip->ip_len) - olen);
   1536 	ip->ip_hl = sizeof (struct ip) >> 2;
   1537 }
   1538 
   1539 const int inetctlerrmap[PRC_NCMDS] = {
   1540 	0,		0,		0,		0,
   1541 	0,		EMSGSIZE,	EHOSTDOWN,	EHOSTUNREACH,
   1542 	EHOSTUNREACH,	EHOSTUNREACH,	ECONNREFUSED,	ECONNREFUSED,
   1543 	EMSGSIZE,	EHOSTUNREACH,	0,		0,
   1544 	0,		0,		0,		0,
   1545 	ENOPROTOOPT
   1546 };
   1547 
   1548 /*
   1549  * Forward a packet.  If some error occurs return the sender
   1550  * an icmp packet.  Note we can't always generate a meaningful
   1551  * icmp message because icmp doesn't have a large enough repertoire
   1552  * of codes and types.
   1553  *
   1554  * If not forwarding, just drop the packet.  This could be confusing
   1555  * if ipforwarding was zero but some routing protocol was advancing
   1556  * us as a gateway to somewhere.  However, we must let the routing
   1557  * protocol deal with that.
   1558  *
   1559  * The srcrt parameter indicates whether the packet is being forwarded
   1560  * via a source route.
   1561  */
   1562 void
   1563 ip_forward(m, srcrt)
   1564 	struct mbuf *m;
   1565 	int srcrt;
   1566 {
   1567 	struct ip *ip = mtod(m, struct ip *);
   1568 	struct sockaddr_in *sin;
   1569 	struct rtentry *rt;
   1570 	int error, type = 0, code = 0;
   1571 	struct mbuf *mcopy;
   1572 	n_long dest;
   1573 	struct ifnet *destifp;
   1574 #ifdef IPSEC
   1575 	struct ifnet dummyifp;
   1576 #endif
   1577 
   1578 	/*
   1579 	 * We are now in the output path.
   1580 	 */
   1581 	MCLAIM(m, &ip_tx_mowner);
   1582 
   1583 	/*
   1584 	 * Clear any in-bound checksum flags for this packet.
   1585 	 */
   1586 	m->m_pkthdr.csum_flags = 0;
   1587 
   1588 	dest = 0;
   1589 #ifdef DIAGNOSTIC
   1590 	if (ipprintfs)
   1591 		printf("forward: src %2.2x dst %2.2x ttl %x\n",
   1592 		    ntohl(ip->ip_src.s_addr),
   1593 		    ntohl(ip->ip_dst.s_addr), ip->ip_ttl);
   1594 #endif
   1595 	if (m->m_flags & (M_BCAST|M_MCAST) || in_canforward(ip->ip_dst) == 0) {
   1596 		ipstat.ips_cantforward++;
   1597 		m_freem(m);
   1598 		return;
   1599 	}
   1600 	if (ip->ip_ttl <= IPTTLDEC) {
   1601 		icmp_error(m, ICMP_TIMXCEED, ICMP_TIMXCEED_INTRANS, dest, 0);
   1602 		return;
   1603 	}
   1604 	ip->ip_ttl -= IPTTLDEC;
   1605 
   1606 	sin = satosin(&ipforward_rt.ro_dst);
   1607 	if ((rt = ipforward_rt.ro_rt) == 0 ||
   1608 	    !in_hosteq(ip->ip_dst, sin->sin_addr)) {
   1609 		if (ipforward_rt.ro_rt) {
   1610 			RTFREE(ipforward_rt.ro_rt);
   1611 			ipforward_rt.ro_rt = 0;
   1612 		}
   1613 		sin->sin_family = AF_INET;
   1614 		sin->sin_len = sizeof(struct sockaddr_in);
   1615 		sin->sin_addr = ip->ip_dst;
   1616 
   1617 		rtalloc(&ipforward_rt);
   1618 		if (ipforward_rt.ro_rt == 0) {
   1619 			icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, dest, 0);
   1620 			return;
   1621 		}
   1622 		rt = ipforward_rt.ro_rt;
   1623 	}
   1624 
   1625 	/*
   1626 	 * Save at most 68 bytes of the packet in case
   1627 	 * we need to generate an ICMP message to the src.
   1628 	 * Pullup to avoid sharing mbuf cluster between m and mcopy.
   1629 	 */
   1630 	mcopy = m_copym(m, 0, imin(ntohs(ip->ip_len), 68), M_DONTWAIT);
   1631 	if (mcopy)
   1632 		mcopy = m_pullup(mcopy, ip->ip_hl << 2);
   1633 
   1634 	/*
   1635 	 * If forwarding packet using same interface that it came in on,
   1636 	 * perhaps should send a redirect to sender to shortcut a hop.
   1637 	 * Only send redirect if source is sending directly to us,
   1638 	 * and if packet was not source routed (or has any options).
   1639 	 * Also, don't send redirect if forwarding using a default route
   1640 	 * or a route modified by a redirect.
   1641 	 */
   1642 	if (rt->rt_ifp == m->m_pkthdr.rcvif &&
   1643 	    (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0 &&
   1644 	    !in_nullhost(satosin(rt_key(rt))->sin_addr) &&
   1645 	    ipsendredirects && !srcrt) {
   1646 		if (rt->rt_ifa &&
   1647 		    (ip->ip_src.s_addr & ifatoia(rt->rt_ifa)->ia_subnetmask) ==
   1648 		    ifatoia(rt->rt_ifa)->ia_subnet) {
   1649 			if (rt->rt_flags & RTF_GATEWAY)
   1650 				dest = satosin(rt->rt_gateway)->sin_addr.s_addr;
   1651 			else
   1652 				dest = ip->ip_dst.s_addr;
   1653 			/*
   1654 			 * Router requirements says to only send host
   1655 			 * redirects.
   1656 			 */
   1657 			type = ICMP_REDIRECT;
   1658 			code = ICMP_REDIRECT_HOST;
   1659 #ifdef DIAGNOSTIC
   1660 			if (ipprintfs)
   1661 				printf("redirect (%d) to %x\n", code,
   1662 				    (u_int32_t)dest);
   1663 #endif
   1664 		}
   1665 	}
   1666 
   1667 #ifdef IPSEC
   1668 	/* Don't lookup socket in forwarding case */
   1669 	(void)ipsec_setsocket(m, NULL);
   1670 #endif
   1671 	error = ip_output(m, (struct mbuf *)0, &ipforward_rt,
   1672 	    (IP_FORWARDING | (ip_directedbcast ? IP_ALLOWBROADCAST : 0)), 0);
   1673 	if (error)
   1674 		ipstat.ips_cantforward++;
   1675 	else {
   1676 		ipstat.ips_forward++;
   1677 		if (type)
   1678 			ipstat.ips_redirectsent++;
   1679 		else {
   1680 			if (mcopy) {
   1681 #ifdef GATEWAY
   1682 				if (mcopy->m_flags & M_CANFASTFWD)
   1683 					ipflow_create(&ipforward_rt, mcopy);
   1684 #endif
   1685 				m_freem(mcopy);
   1686 			}
   1687 			return;
   1688 		}
   1689 	}
   1690 	if (mcopy == NULL)
   1691 		return;
   1692 	destifp = NULL;
   1693 
   1694 	switch (error) {
   1695 
   1696 	case 0:				/* forwarded, but need redirect */
   1697 		/* type, code set above */
   1698 		break;
   1699 
   1700 	case ENETUNREACH:		/* shouldn't happen, checked above */
   1701 	case EHOSTUNREACH:
   1702 	case ENETDOWN:
   1703 	case EHOSTDOWN:
   1704 	default:
   1705 		type = ICMP_UNREACH;
   1706 		code = ICMP_UNREACH_HOST;
   1707 		break;
   1708 
   1709 	case EMSGSIZE:
   1710 		type = ICMP_UNREACH;
   1711 		code = ICMP_UNREACH_NEEDFRAG;
   1712 #ifndef IPSEC
   1713 		if (ipforward_rt.ro_rt)
   1714 			destifp = ipforward_rt.ro_rt->rt_ifp;
   1715 #else
   1716 		/*
   1717 		 * If the packet is routed over IPsec tunnel, tell the
   1718 		 * originator the tunnel MTU.
   1719 		 *	tunnel MTU = if MTU - sizeof(IP) - ESP/AH hdrsiz
   1720 		 * XXX quickhack!!!
   1721 		 */
   1722 		if (ipforward_rt.ro_rt) {
   1723 			struct secpolicy *sp;
   1724 			int ipsecerror;
   1725 			size_t ipsechdr;
   1726 			struct route *ro;
   1727 
   1728 			sp = ipsec4_getpolicybyaddr(mcopy,
   1729 			    IPSEC_DIR_OUTBOUND, IP_FORWARDING,
   1730 			    &ipsecerror);
   1731 
   1732 			if (sp == NULL)
   1733 				destifp = ipforward_rt.ro_rt->rt_ifp;
   1734 			else {
   1735 				/* count IPsec header size */
   1736 				ipsechdr = ipsec4_hdrsiz(mcopy,
   1737 				    IPSEC_DIR_OUTBOUND, NULL);
   1738 
   1739 				/*
   1740 				 * find the correct route for outer IPv4
   1741 				 * header, compute tunnel MTU.
   1742 				 *
   1743 				 * XXX BUG ALERT
   1744 				 * The "dummyifp" code relies upon the fact
   1745 				 * that icmp_error() touches only ifp->if_mtu.
   1746 				 */
   1747 				/*XXX*/
   1748 				destifp = NULL;
   1749 				if (sp->req != NULL
   1750 				 && sp->req->sav != NULL
   1751 				 && sp->req->sav->sah != NULL) {
   1752 					ro = &sp->req->sav->sah->sa_route;
   1753 					if (ro->ro_rt && ro->ro_rt->rt_ifp) {
   1754 						dummyifp.if_mtu =
   1755 						    ro->ro_rt->rt_rmx.rmx_mtu ?
   1756 						    ro->ro_rt->rt_rmx.rmx_mtu :
   1757 						    ro->ro_rt->rt_ifp->if_mtu;
   1758 						dummyifp.if_mtu -= ipsechdr;
   1759 						destifp = &dummyifp;
   1760 					}
   1761 				}
   1762 
   1763 				key_freesp(sp);
   1764 			}
   1765 		}
   1766 #endif /*IPSEC*/
   1767 		ipstat.ips_cantfrag++;
   1768 		break;
   1769 
   1770 	case ENOBUFS:
   1771 #if 1
   1772 		/*
   1773 		 * a router should not generate ICMP_SOURCEQUENCH as
   1774 		 * required in RFC1812 Requirements for IP Version 4 Routers.
   1775 		 * source quench could be a big problem under DoS attacks,
   1776 		 * or if the underlying interface is rate-limited.
   1777 		 */
   1778 		if (mcopy)
   1779 			m_freem(mcopy);
   1780 		return;
   1781 #else
   1782 		type = ICMP_SOURCEQUENCH;
   1783 		code = 0;
   1784 		break;
   1785 #endif
   1786 	}
   1787 	icmp_error(mcopy, type, code, dest, destifp);
   1788 }
   1789 
   1790 void
   1791 ip_savecontrol(inp, mp, ip, m)
   1792 	struct inpcb *inp;
   1793 	struct mbuf **mp;
   1794 	struct ip *ip;
   1795 	struct mbuf *m;
   1796 {
   1797 
   1798 	if (inp->inp_socket->so_options & SO_TIMESTAMP) {
   1799 		struct timeval tv;
   1800 
   1801 		microtime(&tv);
   1802 		*mp = sbcreatecontrol((caddr_t) &tv, sizeof(tv),
   1803 		    SCM_TIMESTAMP, SOL_SOCKET);
   1804 		if (*mp)
   1805 			mp = &(*mp)->m_next;
   1806 	}
   1807 	if (inp->inp_flags & INP_RECVDSTADDR) {
   1808 		*mp = sbcreatecontrol((caddr_t) &ip->ip_dst,
   1809 		    sizeof(struct in_addr), IP_RECVDSTADDR, IPPROTO_IP);
   1810 		if (*mp)
   1811 			mp = &(*mp)->m_next;
   1812 	}
   1813 #ifdef notyet
   1814 	/*
   1815 	 * XXX
   1816 	 * Moving these out of udp_input() made them even more broken
   1817 	 * than they already were.
   1818 	 *	- fenner (at) parc.xerox.com
   1819 	 */
   1820 	/* options were tossed already */
   1821 	if (inp->inp_flags & INP_RECVOPTS) {
   1822 		*mp = sbcreatecontrol((caddr_t) opts_deleted_above,
   1823 		    sizeof(struct in_addr), IP_RECVOPTS, IPPROTO_IP);
   1824 		if (*mp)
   1825 			mp = &(*mp)->m_next;
   1826 	}
   1827 	/* ip_srcroute doesn't do what we want here, need to fix */
   1828 	if (inp->inp_flags & INP_RECVRETOPTS) {
   1829 		*mp = sbcreatecontrol((caddr_t) ip_srcroute(),
   1830 		    sizeof(struct in_addr), IP_RECVRETOPTS, IPPROTO_IP);
   1831 		if (*mp)
   1832 			mp = &(*mp)->m_next;
   1833 	}
   1834 #endif
   1835 	if (inp->inp_flags & INP_RECVIF) {
   1836 		struct sockaddr_dl sdl;
   1837 
   1838 		sdl.sdl_len = offsetof(struct sockaddr_dl, sdl_data[0]);
   1839 		sdl.sdl_family = AF_LINK;
   1840 		sdl.sdl_index = m->m_pkthdr.rcvif ?
   1841 		    m->m_pkthdr.rcvif->if_index : 0;
   1842 		sdl.sdl_nlen = sdl.sdl_alen = sdl.sdl_slen = 0;
   1843 		*mp = sbcreatecontrol((caddr_t) &sdl, sdl.sdl_len,
   1844 		    IP_RECVIF, IPPROTO_IP);
   1845 		if (*mp)
   1846 			mp = &(*mp)->m_next;
   1847 	}
   1848 }
   1849 
   1850 int
   1851 ip_sysctl(name, namelen, oldp, oldlenp, newp, newlen)
   1852 	int *name;
   1853 	u_int namelen;
   1854 	void *oldp;
   1855 	size_t *oldlenp;
   1856 	void *newp;
   1857 	size_t newlen;
   1858 {
   1859 	extern int subnetsarelocal, hostzeroisbroadcast;
   1860 
   1861 	int error, old;
   1862 
   1863 	/* All sysctl names at this level are terminal. */
   1864 	if (namelen != 1)
   1865 		return (ENOTDIR);
   1866 
   1867 	switch (name[0]) {
   1868 	case IPCTL_FORWARDING:
   1869 		return (sysctl_int(oldp, oldlenp, newp, newlen, &ipforwarding));
   1870 	case IPCTL_SENDREDIRECTS:
   1871 		return (sysctl_int(oldp, oldlenp, newp, newlen,
   1872 			&ipsendredirects));
   1873 	case IPCTL_DEFTTL:
   1874 		return (sysctl_int(oldp, oldlenp, newp, newlen, &ip_defttl));
   1875 #ifdef notyet
   1876 	case IPCTL_DEFMTU:
   1877 		return (sysctl_int(oldp, oldlenp, newp, newlen, &ip_mtu));
   1878 #endif
   1879 	case IPCTL_FORWSRCRT:
   1880 		/* Don't allow this to change in a secure environment.  */
   1881 		if (securelevel > 0)
   1882 			return (sysctl_rdint(oldp, oldlenp, newp,
   1883 			    ip_forwsrcrt));
   1884 		else
   1885 			return (sysctl_int(oldp, oldlenp, newp, newlen,
   1886 			    &ip_forwsrcrt));
   1887 	case IPCTL_DIRECTEDBCAST:
   1888 		return (sysctl_int(oldp, oldlenp, newp, newlen,
   1889 		    &ip_directedbcast));
   1890 	case IPCTL_ALLOWSRCRT:
   1891 		return (sysctl_int(oldp, oldlenp, newp, newlen,
   1892 		    &ip_allowsrcrt));
   1893 	case IPCTL_SUBNETSARELOCAL:
   1894 		return (sysctl_int(oldp, oldlenp, newp, newlen,
   1895 		    &subnetsarelocal));
   1896 	case IPCTL_MTUDISC:
   1897 		error = sysctl_int(oldp, oldlenp, newp, newlen,
   1898 		    &ip_mtudisc);
   1899 		if (error == 0 && ip_mtudisc == 0)
   1900 			rt_timer_queue_remove_all(ip_mtudisc_timeout_q, TRUE);
   1901 		return error;
   1902 	case IPCTL_ANONPORTMIN:
   1903 		old = anonportmin;
   1904 		error = sysctl_int(oldp, oldlenp, newp, newlen, &anonportmin);
   1905 		if (anonportmin >= anonportmax || anonportmin < 0
   1906 		    || anonportmin > 65535
   1907 #ifndef IPNOPRIVPORTS
   1908 		    || anonportmin < IPPORT_RESERVED
   1909 #endif
   1910 		    ) {
   1911 			anonportmin = old;
   1912 			return (EINVAL);
   1913 		}
   1914 		return (error);
   1915 	case IPCTL_ANONPORTMAX:
   1916 		old = anonportmax;
   1917 		error = sysctl_int(oldp, oldlenp, newp, newlen, &anonportmax);
   1918 		if (anonportmin >= anonportmax || anonportmax < 0
   1919 		    || anonportmax > 65535
   1920 #ifndef IPNOPRIVPORTS
   1921 		    || anonportmax < IPPORT_RESERVED
   1922 #endif
   1923 		    ) {
   1924 			anonportmax = old;
   1925 			return (EINVAL);
   1926 		}
   1927 		return (error);
   1928 	case IPCTL_MTUDISCTIMEOUT:
   1929 		old = ip_mtudisc_timeout;
   1930 		error = sysctl_int(oldp, oldlenp, newp, newlen,
   1931 		   &ip_mtudisc_timeout);
   1932 		if (ip_mtudisc_timeout < 0) {
   1933 			ip_mtudisc_timeout = old;
   1934 			return (EINVAL);
   1935 		}
   1936 		if (error == 0)
   1937 			rt_timer_queue_change(ip_mtudisc_timeout_q,
   1938 					      ip_mtudisc_timeout);
   1939 		return (error);
   1940 #ifdef GATEWAY
   1941 	case IPCTL_MAXFLOWS:
   1942 	    {
   1943 		int s;
   1944 
   1945 		error = sysctl_int(oldp, oldlenp, newp, newlen,
   1946 		   &ip_maxflows);
   1947 		s = splsoftnet();
   1948 		ipflow_reap(0);
   1949 		splx(s);
   1950 		return (error);
   1951 	    }
   1952 #endif
   1953 	case IPCTL_HOSTZEROBROADCAST:
   1954 		return (sysctl_int(oldp, oldlenp, newp, newlen,
   1955 		    &hostzeroisbroadcast));
   1956 #if NGIF > 0
   1957 	case IPCTL_GIF_TTL:
   1958 		return (sysctl_int(oldp, oldlenp, newp, newlen,
   1959 				  &ip_gif_ttl));
   1960 #endif
   1961 
   1962 #if NGRE > 0
   1963 	case IPCTL_GRE_TTL:
   1964 		return (sysctl_int(oldp, oldlenp, newp, newlen,
   1965 				  &ip_gre_ttl));
   1966 #endif
   1967 
   1968 #ifndef IPNOPRIVPORTS
   1969 	case IPCTL_LOWPORTMIN:
   1970 		old = lowportmin;
   1971 		error = sysctl_int(oldp, oldlenp, newp, newlen, &lowportmin);
   1972 		if (lowportmin >= lowportmax
   1973 		    || lowportmin > IPPORT_RESERVEDMAX
   1974 		    || lowportmin < IPPORT_RESERVEDMIN
   1975 		    ) {
   1976 			lowportmin = old;
   1977 			return (EINVAL);
   1978 		}
   1979 		return (error);
   1980 	case IPCTL_LOWPORTMAX:
   1981 		old = lowportmax;
   1982 		error = sysctl_int(oldp, oldlenp, newp, newlen, &lowportmax);
   1983 		if (lowportmin >= lowportmax
   1984 		    || lowportmax > IPPORT_RESERVEDMAX
   1985 		    || lowportmax < IPPORT_RESERVEDMIN
   1986 		    ) {
   1987 			lowportmax = old;
   1988 			return (EINVAL);
   1989 		}
   1990 		return (error);
   1991 #endif
   1992 
   1993 	case IPCTL_MAXFRAGPACKETS:
   1994 		return (sysctl_int(oldp, oldlenp, newp, newlen,
   1995 		    &ip_maxfragpackets));
   1996 
   1997 	case IPCTL_CHECKINTERFACE:
   1998 		return (sysctl_int(oldp, oldlenp, newp, newlen,
   1999 		    &ip_checkinterface));
   2000 	default:
   2001 		return (EOPNOTSUPP);
   2002 	}
   2003 	/* NOTREACHED */
   2004 }
   2005