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ip_input.c revision 1.171
      1 /*	$NetBSD: ip_input.c,v 1.171 2003/07/14 16:39:43 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 1.171 2003/07/14 16:39:43 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_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 	int srcrt = 0;
    436 
    437 	MCLAIM(m, &ip_rx_mowner);
    438 #ifdef	DIAGNOSTIC
    439 	if ((m->m_flags & M_PKTHDR) == 0)
    440 		panic("ipintr no HDR");
    441 #endif
    442 #ifdef IPSEC
    443 	/*
    444 	 * should the inner packet be considered authentic?
    445 	 * see comment in ah4_input().
    446 	 */
    447 	if (m) {
    448 		m->m_flags &= ~M_AUTHIPHDR;
    449 		m->m_flags &= ~M_AUTHIPDGM;
    450 	}
    451 #endif
    452 
    453 	/*
    454 	 * If no IP addresses have been set yet but the interfaces
    455 	 * are receiving, can't do anything with incoming packets yet.
    456 	 */
    457 	if (TAILQ_FIRST(&in_ifaddr) == 0)
    458 		goto bad;
    459 	ipstat.ips_total++;
    460 	/*
    461 	 * If the IP header is not aligned, slurp it up into a new
    462 	 * mbuf with space for link headers, in the event we forward
    463 	 * it.  Otherwise, if it is aligned, make sure the entire
    464 	 * base IP header is in the first mbuf of the chain.
    465 	 */
    466 	if (IP_HDR_ALIGNED_P(mtod(m, caddr_t)) == 0) {
    467 		if ((m = m_copyup(m, sizeof(struct ip),
    468 				  (max_linkhdr + 3) & ~3)) == NULL) {
    469 			/* XXXJRT new stat, please */
    470 			ipstat.ips_toosmall++;
    471 			return;
    472 		}
    473 	} else if (__predict_false(m->m_len < sizeof (struct ip))) {
    474 		if ((m = m_pullup(m, sizeof (struct ip))) == NULL) {
    475 			ipstat.ips_toosmall++;
    476 			return;
    477 		}
    478 	}
    479 	ip = mtod(m, struct ip *);
    480 	if (ip->ip_v != IPVERSION) {
    481 		ipstat.ips_badvers++;
    482 		goto bad;
    483 	}
    484 	hlen = ip->ip_hl << 2;
    485 	if (hlen < sizeof(struct ip)) {	/* minimum header length */
    486 		ipstat.ips_badhlen++;
    487 		goto bad;
    488 	}
    489 	if (hlen > m->m_len) {
    490 		if ((m = m_pullup(m, hlen)) == 0) {
    491 			ipstat.ips_badhlen++;
    492 			return;
    493 		}
    494 		ip = mtod(m, struct ip *);
    495 	}
    496 
    497 	/*
    498 	 * RFC1122: packets with a multicast source address are
    499 	 * not allowed.
    500 	 */
    501 	if (IN_MULTICAST(ip->ip_src.s_addr)) {
    502 		ipstat.ips_badaddr++;
    503 		goto bad;
    504 	}
    505 
    506 	/* 127/8 must not appear on wire - RFC1122 */
    507 	if ((ntohl(ip->ip_dst.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET ||
    508 	    (ntohl(ip->ip_src.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET) {
    509 		if ((m->m_pkthdr.rcvif->if_flags & IFF_LOOPBACK) == 0) {
    510 			ipstat.ips_badaddr++;
    511 			goto bad;
    512 		}
    513 	}
    514 
    515 	switch (m->m_pkthdr.csum_flags &
    516 		((m->m_pkthdr.rcvif->if_csum_flags_rx & M_CSUM_IPv4) |
    517 		 M_CSUM_IPv4_BAD)) {
    518 	case M_CSUM_IPv4|M_CSUM_IPv4_BAD:
    519 		INET_CSUM_COUNTER_INCR(&ip_hwcsum_bad);
    520 		goto badcsum;
    521 
    522 	case M_CSUM_IPv4:
    523 		/* Checksum was okay. */
    524 		INET_CSUM_COUNTER_INCR(&ip_hwcsum_ok);
    525 		break;
    526 
    527 	default:
    528 		/* Must compute it ourselves. */
    529 		INET_CSUM_COUNTER_INCR(&ip_swcsum);
    530 		if (in_cksum(m, hlen) != 0)
    531 			goto bad;
    532 		break;
    533 	}
    534 
    535 	/* Retrieve the packet length. */
    536 	len = ntohs(ip->ip_len);
    537 
    538 	/*
    539 	 * Check for additional length bogosity
    540 	 */
    541 	if (len < hlen) {
    542 	 	ipstat.ips_badlen++;
    543 		goto bad;
    544 	}
    545 
    546 	/*
    547 	 * Check that the amount of data in the buffers
    548 	 * is as at least much as the IP header would have us expect.
    549 	 * Trim mbufs if longer than we expect.
    550 	 * Drop packet if shorter than we expect.
    551 	 */
    552 	if (m->m_pkthdr.len < len) {
    553 		ipstat.ips_tooshort++;
    554 		goto bad;
    555 	}
    556 	if (m->m_pkthdr.len > len) {
    557 		if (m->m_len == m->m_pkthdr.len) {
    558 			m->m_len = len;
    559 			m->m_pkthdr.len = len;
    560 		} else
    561 			m_adj(m, len - m->m_pkthdr.len);
    562 	}
    563 
    564 #ifdef IPSEC
    565 	/* ipflow (IP fast forwarding) is not compatible with IPsec. */
    566 	m->m_flags &= ~M_CANFASTFWD;
    567 #else
    568 	/*
    569 	 * Assume that we can create a fast-forward IP flow entry
    570 	 * based on this packet.
    571 	 */
    572 	m->m_flags |= M_CANFASTFWD;
    573 #endif
    574 
    575 #ifdef PFIL_HOOKS
    576 	/*
    577 	 * Run through list of hooks for input packets.  If there are any
    578 	 * filters which require that additional packets in the flow are
    579 	 * not fast-forwarded, they must clear the M_CANFASTFWD flag.
    580 	 * Note that filters must _never_ set this flag, as another filter
    581 	 * in the list may have previously cleared it.
    582 	 */
    583 	/*
    584 	 * let ipfilter look at packet on the wire,
    585 	 * not the decapsulated packet.
    586 	 */
    587 #ifdef IPSEC
    588 	if (!ipsec_getnhist(m))
    589 #else
    590 	if (1)
    591 #endif
    592 	{
    593 		struct in_addr odst;
    594 
    595 		odst = ip->ip_dst;
    596 		if (pfil_run_hooks(&inet_pfil_hook, &m, m->m_pkthdr.rcvif,
    597 		    PFIL_IN) != 0)
    598 			return;
    599 		if (m == NULL)
    600 			return;
    601 		ip = mtod(m, struct ip *);
    602 		hlen = ip->ip_hl << 2;
    603 		srcrt = (odst.s_addr != ip->ip_dst.s_addr);
    604 	}
    605 #endif /* PFIL_HOOKS */
    606 
    607 #ifdef ALTQ
    608 	/* XXX Temporary until ALTQ is changed to use a pfil hook */
    609 	if (altq_input != NULL && (*altq_input)(m, AF_INET) == 0) {
    610 		/* packet dropped by traffic conditioner */
    611 		return;
    612 	}
    613 #endif
    614 
    615 	/*
    616 	 * Process options and, if not destined for us,
    617 	 * ship it on.  ip_dooptions returns 1 when an
    618 	 * error was detected (causing an icmp message
    619 	 * to be sent and the original packet to be freed).
    620 	 */
    621 	ip_nhops = 0;		/* for source routed packets */
    622 	if (hlen > sizeof (struct ip) && ip_dooptions(m))
    623 		return;
    624 
    625 	/*
    626 	 * Enable a consistency check between the destination address
    627 	 * and the arrival interface for a unicast packet (the RFC 1122
    628 	 * strong ES model) if IP forwarding is disabled and the packet
    629 	 * is not locally generated.
    630 	 *
    631 	 * XXX - Checking also should be disabled if the destination
    632 	 * address is ipnat'ed to a different interface.
    633 	 *
    634 	 * XXX - Checking is incompatible with IP aliases added
    635 	 * to the loopback interface instead of the interface where
    636 	 * the packets are received.
    637 	 *
    638 	 * XXX - We need to add a per ifaddr flag for this so that
    639 	 * we get finer grain control.
    640 	 */
    641 	checkif = ip_checkinterface && (ipforwarding == 0) &&
    642 	    (m->m_pkthdr.rcvif != NULL) &&
    643 	    ((m->m_pkthdr.rcvif->if_flags & IFF_LOOPBACK) == 0);
    644 
    645 	/*
    646 	 * Check our list of addresses, to see if the packet is for us.
    647 	 *
    648 	 * Traditional 4.4BSD did not consult IFF_UP at all.
    649 	 * The behavior here is to treat addresses on !IFF_UP interface
    650 	 * as not mine.
    651 	 */
    652 	downmatch = 0;
    653 	LIST_FOREACH(ia, &IN_IFADDR_HASH(ip->ip_dst.s_addr), ia_hash) {
    654 		if (in_hosteq(ia->ia_addr.sin_addr, ip->ip_dst)) {
    655 			if (checkif && ia->ia_ifp != m->m_pkthdr.rcvif)
    656 				continue;
    657 			if ((ia->ia_ifp->if_flags & IFF_UP) != 0)
    658 				break;
    659 			else
    660 				downmatch++;
    661 		}
    662 	}
    663 	if (ia != NULL)
    664 		goto ours;
    665 	if (m->m_pkthdr.rcvif->if_flags & IFF_BROADCAST) {
    666 		TAILQ_FOREACH(ifa, &m->m_pkthdr.rcvif->if_addrlist, ifa_list) {
    667 			if (ifa->ifa_addr->sa_family != AF_INET)
    668 				continue;
    669 			ia = ifatoia(ifa);
    670 			if (in_hosteq(ip->ip_dst, ia->ia_broadaddr.sin_addr) ||
    671 			    in_hosteq(ip->ip_dst, ia->ia_netbroadcast) ||
    672 			    /*
    673 			     * Look for all-0's host part (old broadcast addr),
    674 			     * either for subnet or net.
    675 			     */
    676 			    ip->ip_dst.s_addr == ia->ia_subnet ||
    677 			    ip->ip_dst.s_addr == ia->ia_net)
    678 				goto ours;
    679 			/*
    680 			 * An interface with IP address zero accepts
    681 			 * all packets that arrive on that interface.
    682 			 */
    683 			if (in_nullhost(ia->ia_addr.sin_addr))
    684 				goto ours;
    685 		}
    686 	}
    687 	if (IN_MULTICAST(ip->ip_dst.s_addr)) {
    688 		struct in_multi *inm;
    689 #ifdef MROUTING
    690 		extern struct socket *ip_mrouter;
    691 
    692 		if (M_READONLY(m)) {
    693 			if ((m = m_pullup(m, hlen)) == 0) {
    694 				ipstat.ips_toosmall++;
    695 				return;
    696 			}
    697 			ip = mtod(m, struct ip *);
    698 		}
    699 
    700 		if (ip_mrouter) {
    701 			/*
    702 			 * If we are acting as a multicast router, all
    703 			 * incoming multicast packets are passed to the
    704 			 * kernel-level multicast forwarding function.
    705 			 * The packet is returned (relatively) intact; if
    706 			 * ip_mforward() returns a non-zero value, the packet
    707 			 * must be discarded, else it may be accepted below.
    708 			 *
    709 			 * (The IP ident field is put in the same byte order
    710 			 * as expected when ip_mforward() is called from
    711 			 * ip_output().)
    712 			 */
    713 			if (ip_mforward(m, m->m_pkthdr.rcvif) != 0) {
    714 				ipstat.ips_cantforward++;
    715 				m_freem(m);
    716 				return;
    717 			}
    718 
    719 			/*
    720 			 * The process-level routing demon needs to receive
    721 			 * all multicast IGMP packets, whether or not this
    722 			 * host belongs to their destination groups.
    723 			 */
    724 			if (ip->ip_p == IPPROTO_IGMP)
    725 				goto ours;
    726 			ipstat.ips_forward++;
    727 		}
    728 #endif
    729 		/*
    730 		 * See if we belong to the destination multicast group on the
    731 		 * arrival interface.
    732 		 */
    733 		IN_LOOKUP_MULTI(ip->ip_dst, m->m_pkthdr.rcvif, inm);
    734 		if (inm == NULL) {
    735 			ipstat.ips_cantforward++;
    736 			m_freem(m);
    737 			return;
    738 		}
    739 		goto ours;
    740 	}
    741 	if (ip->ip_dst.s_addr == INADDR_BROADCAST ||
    742 	    in_nullhost(ip->ip_dst))
    743 		goto ours;
    744 
    745 	/*
    746 	 * Not for us; forward if possible and desirable.
    747 	 */
    748 	if (ipforwarding == 0) {
    749 		ipstat.ips_cantforward++;
    750 		m_freem(m);
    751 	} else {
    752 		/*
    753 		 * If ip_dst matched any of my address on !IFF_UP interface,
    754 		 * and there's no IFF_UP interface that matches ip_dst,
    755 		 * send icmp unreach.  Forwarding it will result in in-kernel
    756 		 * forwarding loop till TTL goes to 0.
    757 		 */
    758 		if (downmatch) {
    759 			icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, 0, 0);
    760 			ipstat.ips_cantforward++;
    761 			return;
    762 		}
    763 #ifdef IPSEC
    764 		if (ipsec4_in_reject(m, NULL)) {
    765 			ipsecstat.in_polvio++;
    766 			goto bad;
    767 		}
    768 #endif
    769 
    770 		ip_forward(m, srcrt);
    771 	}
    772 	return;
    773 
    774 ours:
    775 	/*
    776 	 * If offset or IP_MF are set, must reassemble.
    777 	 * Otherwise, nothing need be done.
    778 	 * (We could look in the reassembly queue to see
    779 	 * if the packet was previously fragmented,
    780 	 * but it's not worth the time; just let them time out.)
    781 	 */
    782 	if (ip->ip_off & ~htons(IP_DF|IP_RF)) {
    783 		if (M_READONLY(m)) {
    784 			if ((m = m_pullup(m, hlen)) == NULL) {
    785 				ipstat.ips_toosmall++;
    786 				goto bad;
    787 			}
    788 			ip = mtod(m, struct ip *);
    789 		}
    790 
    791 		/*
    792 		 * Look for queue of fragments
    793 		 * of this datagram.
    794 		 */
    795 		IPQ_LOCK();
    796 		LIST_FOREACH(fp, &ipq, ipq_q)
    797 			if (ip->ip_id == fp->ipq_id &&
    798 			    in_hosteq(ip->ip_src, fp->ipq_src) &&
    799 			    in_hosteq(ip->ip_dst, fp->ipq_dst) &&
    800 			    ip->ip_p == fp->ipq_p)
    801 				goto found;
    802 		fp = 0;
    803 found:
    804 
    805 		/*
    806 		 * Adjust ip_len to not reflect header,
    807 		 * set ipqe_mff if more fragments are expected,
    808 		 * convert offset of this to bytes.
    809 		 */
    810 		ip->ip_len = htons(ntohs(ip->ip_len) - hlen);
    811 		mff = (ip->ip_off & htons(IP_MF)) != 0;
    812 		if (mff) {
    813 		        /*
    814 		         * Make sure that fragments have a data length
    815 			 * that's a non-zero multiple of 8 bytes.
    816 		         */
    817 			if (ntohs(ip->ip_len) == 0 ||
    818 			    (ntohs(ip->ip_len) & 0x7) != 0) {
    819 				ipstat.ips_badfrags++;
    820 				IPQ_UNLOCK();
    821 				goto bad;
    822 			}
    823 		}
    824 		ip->ip_off = htons((ntohs(ip->ip_off) & IP_OFFMASK) << 3);
    825 
    826 		/*
    827 		 * If datagram marked as having more fragments
    828 		 * or if this is not the first fragment,
    829 		 * attempt reassembly; if it succeeds, proceed.
    830 		 */
    831 		if (mff || ip->ip_off != htons(0)) {
    832 			ipstat.ips_fragments++;
    833 			ipqe = pool_get(&ipqent_pool, PR_NOWAIT);
    834 			if (ipqe == NULL) {
    835 				ipstat.ips_rcvmemdrop++;
    836 				IPQ_UNLOCK();
    837 				goto bad;
    838 			}
    839 			ipqe->ipqe_mff = mff;
    840 			ipqe->ipqe_m = m;
    841 			ipqe->ipqe_ip = ip;
    842 			m = ip_reass(ipqe, fp);
    843 			if (m == 0) {
    844 				IPQ_UNLOCK();
    845 				return;
    846 			}
    847 			ipstat.ips_reassembled++;
    848 			ip = mtod(m, struct ip *);
    849 			hlen = ip->ip_hl << 2;
    850 			ip->ip_len = htons(ntohs(ip->ip_len) + hlen);
    851 		} else
    852 			if (fp)
    853 				ip_freef(fp);
    854 		IPQ_UNLOCK();
    855 	}
    856 
    857 #ifdef IPSEC
    858 	/*
    859 	 * enforce IPsec policy checking if we are seeing last header.
    860 	 * note that we do not visit this with protocols with pcb layer
    861 	 * code - like udp/tcp/raw ip.
    862 	 */
    863 	if ((inetsw[ip_protox[ip->ip_p]].pr_flags & PR_LASTHDR) != 0 &&
    864 	    ipsec4_in_reject(m, NULL)) {
    865 		ipsecstat.in_polvio++;
    866 		goto bad;
    867 	}
    868 #endif
    869 
    870 	/*
    871 	 * Switch out to protocol's input routine.
    872 	 */
    873 #if IFA_STATS
    874 	if (ia && ip)
    875 		ia->ia_ifa.ifa_data.ifad_inbytes += ntohs(ip->ip_len);
    876 #endif
    877 	ipstat.ips_delivered++;
    878     {
    879 	int off = hlen, nh = ip->ip_p;
    880 
    881 	(*inetsw[ip_protox[nh]].pr_input)(m, off, nh);
    882 	return;
    883     }
    884 bad:
    885 	m_freem(m);
    886 	return;
    887 
    888 badcsum:
    889 	ipstat.ips_badsum++;
    890 	m_freem(m);
    891 }
    892 
    893 /*
    894  * Take incoming datagram fragment and try to
    895  * reassemble it into whole datagram.  If a chain for
    896  * reassembly of this datagram already exists, then it
    897  * is given as fp; otherwise have to make a chain.
    898  */
    899 struct mbuf *
    900 ip_reass(ipqe, fp)
    901 	struct ipqent *ipqe;
    902 	struct ipq *fp;
    903 {
    904 	struct mbuf *m = ipqe->ipqe_m;
    905 	struct ipqent *nq, *p, *q;
    906 	struct ip *ip;
    907 	struct mbuf *t;
    908 	int hlen = ipqe->ipqe_ip->ip_hl << 2;
    909 	int i, next;
    910 
    911 	IPQ_LOCK_CHECK();
    912 
    913 	/*
    914 	 * Presence of header sizes in mbufs
    915 	 * would confuse code below.
    916 	 */
    917 	m->m_data += hlen;
    918 	m->m_len -= hlen;
    919 
    920 	/*
    921 	 * If first fragment to arrive, create a reassembly queue.
    922 	 */
    923 	if (fp == 0) {
    924 		/*
    925 		 * Enforce upper bound on number of fragmented packets
    926 		 * for which we attempt reassembly;
    927 		 * If maxfrag is 0, never accept fragments.
    928 		 * If maxfrag is -1, accept all fragments without limitation.
    929 		 */
    930 		if (ip_maxfragpackets < 0)
    931 			;
    932 		else if (ip_nfragpackets >= ip_maxfragpackets)
    933 			goto dropfrag;
    934 		ip_nfragpackets++;
    935 		MALLOC(fp, struct ipq *, sizeof (struct ipq),
    936 		    M_FTABLE, M_NOWAIT);
    937 		if (fp == NULL)
    938 			goto dropfrag;
    939 		LIST_INSERT_HEAD(&ipq, fp, ipq_q);
    940 		fp->ipq_ttl = IPFRAGTTL;
    941 		fp->ipq_p = ipqe->ipqe_ip->ip_p;
    942 		fp->ipq_id = ipqe->ipqe_ip->ip_id;
    943 		TAILQ_INIT(&fp->ipq_fragq);
    944 		fp->ipq_src = ipqe->ipqe_ip->ip_src;
    945 		fp->ipq_dst = ipqe->ipqe_ip->ip_dst;
    946 		p = NULL;
    947 		goto insert;
    948 	}
    949 
    950 	/*
    951 	 * Find a segment which begins after this one does.
    952 	 */
    953 	for (p = NULL, q = TAILQ_FIRST(&fp->ipq_fragq); q != NULL;
    954 	    p = q, q = TAILQ_NEXT(q, ipqe_q))
    955 		if (ntohs(q->ipqe_ip->ip_off) > ntohs(ipqe->ipqe_ip->ip_off))
    956 			break;
    957 
    958 	/*
    959 	 * If there is a preceding segment, it may provide some of
    960 	 * our data already.  If so, drop the data from the incoming
    961 	 * segment.  If it provides all of our data, drop us.
    962 	 */
    963 	if (p != NULL) {
    964 		i = ntohs(p->ipqe_ip->ip_off) + ntohs(p->ipqe_ip->ip_len) -
    965 		    ntohs(ipqe->ipqe_ip->ip_off);
    966 		if (i > 0) {
    967 			if (i >= ntohs(ipqe->ipqe_ip->ip_len))
    968 				goto dropfrag;
    969 			m_adj(ipqe->ipqe_m, i);
    970 			ipqe->ipqe_ip->ip_off =
    971 			    htons(ntohs(ipqe->ipqe_ip->ip_off) + i);
    972 			ipqe->ipqe_ip->ip_len =
    973 			    htons(ntohs(ipqe->ipqe_ip->ip_len) - i);
    974 		}
    975 	}
    976 
    977 	/*
    978 	 * While we overlap succeeding segments trim them or,
    979 	 * if they are completely covered, dequeue them.
    980 	 */
    981 	for (; q != NULL &&
    982 	    ntohs(ipqe->ipqe_ip->ip_off) + ntohs(ipqe->ipqe_ip->ip_len) >
    983 	    ntohs(q->ipqe_ip->ip_off); q = nq) {
    984 		i = (ntohs(ipqe->ipqe_ip->ip_off) +
    985 		    ntohs(ipqe->ipqe_ip->ip_len)) - ntohs(q->ipqe_ip->ip_off);
    986 		if (i < ntohs(q->ipqe_ip->ip_len)) {
    987 			q->ipqe_ip->ip_len =
    988 			    htons(ntohs(q->ipqe_ip->ip_len) - i);
    989 			q->ipqe_ip->ip_off =
    990 			    htons(ntohs(q->ipqe_ip->ip_off) + i);
    991 			m_adj(q->ipqe_m, i);
    992 			break;
    993 		}
    994 		nq = TAILQ_NEXT(q, ipqe_q);
    995 		m_freem(q->ipqe_m);
    996 		TAILQ_REMOVE(&fp->ipq_fragq, q, ipqe_q);
    997 		pool_put(&ipqent_pool, q);
    998 	}
    999 
   1000 insert:
   1001 	/*
   1002 	 * Stick new segment in its place;
   1003 	 * check for complete reassembly.
   1004 	 */
   1005 	if (p == NULL) {
   1006 		TAILQ_INSERT_HEAD(&fp->ipq_fragq, ipqe, ipqe_q);
   1007 	} else {
   1008 		TAILQ_INSERT_AFTER(&fp->ipq_fragq, p, ipqe, ipqe_q);
   1009 	}
   1010 	next = 0;
   1011 	for (p = NULL, q = TAILQ_FIRST(&fp->ipq_fragq); q != NULL;
   1012 	    p = q, q = TAILQ_NEXT(q, ipqe_q)) {
   1013 		if (ntohs(q->ipqe_ip->ip_off) != next)
   1014 			return (0);
   1015 		next += ntohs(q->ipqe_ip->ip_len);
   1016 	}
   1017 	if (p->ipqe_mff)
   1018 		return (0);
   1019 
   1020 	/*
   1021 	 * Reassembly is complete.  Check for a bogus message size and
   1022 	 * concatenate fragments.
   1023 	 */
   1024 	q = TAILQ_FIRST(&fp->ipq_fragq);
   1025 	ip = q->ipqe_ip;
   1026 	if ((next + (ip->ip_hl << 2)) > IP_MAXPACKET) {
   1027 		ipstat.ips_toolong++;
   1028 		ip_freef(fp);
   1029 		return (0);
   1030 	}
   1031 	m = q->ipqe_m;
   1032 	t = m->m_next;
   1033 	m->m_next = 0;
   1034 	m_cat(m, t);
   1035 	nq = TAILQ_NEXT(q, ipqe_q);
   1036 	pool_put(&ipqent_pool, q);
   1037 	for (q = nq; q != NULL; q = nq) {
   1038 		t = q->ipqe_m;
   1039 		nq = TAILQ_NEXT(q, ipqe_q);
   1040 		pool_put(&ipqent_pool, q);
   1041 		m_cat(m, t);
   1042 	}
   1043 
   1044 	/*
   1045 	 * Create header for new ip packet by
   1046 	 * modifying header of first packet;
   1047 	 * dequeue and discard fragment reassembly header.
   1048 	 * Make header visible.
   1049 	 */
   1050 	ip->ip_len = htons(next);
   1051 	ip->ip_src = fp->ipq_src;
   1052 	ip->ip_dst = fp->ipq_dst;
   1053 	LIST_REMOVE(fp, ipq_q);
   1054 	FREE(fp, M_FTABLE);
   1055 	ip_nfragpackets--;
   1056 	m->m_len += (ip->ip_hl << 2);
   1057 	m->m_data -= (ip->ip_hl << 2);
   1058 	/* some debugging cruft by sklower, below, will go away soon */
   1059 	if (m->m_flags & M_PKTHDR) { /* XXX this should be done elsewhere */
   1060 		int plen = 0;
   1061 		for (t = m; t; t = t->m_next)
   1062 			plen += t->m_len;
   1063 		m->m_pkthdr.len = plen;
   1064 	}
   1065 	return (m);
   1066 
   1067 dropfrag:
   1068 	ipstat.ips_fragdropped++;
   1069 	m_freem(m);
   1070 	pool_put(&ipqent_pool, ipqe);
   1071 	return (0);
   1072 }
   1073 
   1074 /*
   1075  * Free a fragment reassembly header and all
   1076  * associated datagrams.
   1077  */
   1078 void
   1079 ip_freef(fp)
   1080 	struct ipq *fp;
   1081 {
   1082 	struct ipqent *q, *p;
   1083 
   1084 	IPQ_LOCK_CHECK();
   1085 
   1086 	for (q = TAILQ_FIRST(&fp->ipq_fragq); q != NULL; q = p) {
   1087 		p = TAILQ_NEXT(q, ipqe_q);
   1088 		m_freem(q->ipqe_m);
   1089 		TAILQ_REMOVE(&fp->ipq_fragq, q, ipqe_q);
   1090 		pool_put(&ipqent_pool, q);
   1091 	}
   1092 	LIST_REMOVE(fp, ipq_q);
   1093 	FREE(fp, M_FTABLE);
   1094 	ip_nfragpackets--;
   1095 }
   1096 
   1097 /*
   1098  * IP timer processing;
   1099  * if a timer expires on a reassembly
   1100  * queue, discard it.
   1101  */
   1102 void
   1103 ip_slowtimo()
   1104 {
   1105 	struct ipq *fp, *nfp;
   1106 	int s = splsoftnet();
   1107 
   1108 	IPQ_LOCK();
   1109 	for (fp = LIST_FIRST(&ipq); fp != NULL; fp = nfp) {
   1110 		nfp = LIST_NEXT(fp, ipq_q);
   1111 		if (--fp->ipq_ttl == 0) {
   1112 			ipstat.ips_fragtimeout++;
   1113 			ip_freef(fp);
   1114 		}
   1115 	}
   1116 	/*
   1117 	 * If we are over the maximum number of fragments
   1118 	 * (due to the limit being lowered), drain off
   1119 	 * enough to get down to the new limit.
   1120 	 */
   1121 	if (ip_maxfragpackets < 0)
   1122 		;
   1123 	else {
   1124 		while (ip_nfragpackets > ip_maxfragpackets && LIST_FIRST(&ipq))
   1125 			ip_freef(LIST_FIRST(&ipq));
   1126 	}
   1127 	IPQ_UNLOCK();
   1128 #ifdef GATEWAY
   1129 	ipflow_slowtimo();
   1130 #endif
   1131 	splx(s);
   1132 }
   1133 
   1134 /*
   1135  * Drain off all datagram fragments.
   1136  */
   1137 void
   1138 ip_drain()
   1139 {
   1140 
   1141 	/*
   1142 	 * We may be called from a device's interrupt context.  If
   1143 	 * the ipq is already busy, just bail out now.
   1144 	 */
   1145 	if (ipq_lock_try() == 0)
   1146 		return;
   1147 
   1148 	while (LIST_FIRST(&ipq) != NULL) {
   1149 		ipstat.ips_fragdropped++;
   1150 		ip_freef(LIST_FIRST(&ipq));
   1151 	}
   1152 
   1153 	IPQ_UNLOCK();
   1154 }
   1155 
   1156 /*
   1157  * Do option processing on a datagram,
   1158  * possibly discarding it if bad options are encountered,
   1159  * or forwarding it if source-routed.
   1160  * Returns 1 if packet has been forwarded/freed,
   1161  * 0 if the packet should be processed further.
   1162  */
   1163 int
   1164 ip_dooptions(m)
   1165 	struct mbuf *m;
   1166 {
   1167 	struct ip *ip = mtod(m, struct ip *);
   1168 	u_char *cp, *cp0;
   1169 	struct ip_timestamp *ipt;
   1170 	struct in_ifaddr *ia;
   1171 	int opt, optlen, cnt, off, code, type = ICMP_PARAMPROB, forward = 0;
   1172 	struct in_addr dst;
   1173 	n_time ntime;
   1174 
   1175 	dst = ip->ip_dst;
   1176 	cp = (u_char *)(ip + 1);
   1177 	cnt = (ip->ip_hl << 2) - sizeof (struct ip);
   1178 	for (; cnt > 0; cnt -= optlen, cp += optlen) {
   1179 		opt = cp[IPOPT_OPTVAL];
   1180 		if (opt == IPOPT_EOL)
   1181 			break;
   1182 		if (opt == IPOPT_NOP)
   1183 			optlen = 1;
   1184 		else {
   1185 			if (cnt < IPOPT_OLEN + sizeof(*cp)) {
   1186 				code = &cp[IPOPT_OLEN] - (u_char *)ip;
   1187 				goto bad;
   1188 			}
   1189 			optlen = cp[IPOPT_OLEN];
   1190 			if (optlen < IPOPT_OLEN + sizeof(*cp) || optlen > cnt) {
   1191 				code = &cp[IPOPT_OLEN] - (u_char *)ip;
   1192 				goto bad;
   1193 			}
   1194 		}
   1195 		switch (opt) {
   1196 
   1197 		default:
   1198 			break;
   1199 
   1200 		/*
   1201 		 * Source routing with record.
   1202 		 * Find interface with current destination address.
   1203 		 * If none on this machine then drop if strictly routed,
   1204 		 * or do nothing if loosely routed.
   1205 		 * Record interface address and bring up next address
   1206 		 * component.  If strictly routed make sure next
   1207 		 * address is on directly accessible net.
   1208 		 */
   1209 		case IPOPT_LSRR:
   1210 		case IPOPT_SSRR:
   1211 			if (ip_allowsrcrt == 0) {
   1212 				type = ICMP_UNREACH;
   1213 				code = ICMP_UNREACH_NET_PROHIB;
   1214 				goto bad;
   1215 			}
   1216 			if (optlen < IPOPT_OFFSET + sizeof(*cp)) {
   1217 				code = &cp[IPOPT_OLEN] - (u_char *)ip;
   1218 				goto bad;
   1219 			}
   1220 			if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
   1221 				code = &cp[IPOPT_OFFSET] - (u_char *)ip;
   1222 				goto bad;
   1223 			}
   1224 			ipaddr.sin_addr = ip->ip_dst;
   1225 			ia = ifatoia(ifa_ifwithaddr(sintosa(&ipaddr)));
   1226 			if (ia == 0) {
   1227 				if (opt == IPOPT_SSRR) {
   1228 					type = ICMP_UNREACH;
   1229 					code = ICMP_UNREACH_SRCFAIL;
   1230 					goto bad;
   1231 				}
   1232 				/*
   1233 				 * Loose routing, and not at next destination
   1234 				 * yet; nothing to do except forward.
   1235 				 */
   1236 				break;
   1237 			}
   1238 			off--;			/* 0 origin */
   1239 			if ((off + sizeof(struct in_addr)) > optlen) {
   1240 				/*
   1241 				 * End of source route.  Should be for us.
   1242 				 */
   1243 				save_rte(cp, ip->ip_src);
   1244 				break;
   1245 			}
   1246 			/*
   1247 			 * locate outgoing interface
   1248 			 */
   1249 			bcopy((caddr_t)(cp + off), (caddr_t)&ipaddr.sin_addr,
   1250 			    sizeof(ipaddr.sin_addr));
   1251 			if (opt == IPOPT_SSRR)
   1252 				ia = ifatoia(ifa_ifwithaddr(sintosa(&ipaddr)));
   1253 			else
   1254 				ia = ip_rtaddr(ipaddr.sin_addr);
   1255 			if (ia == 0) {
   1256 				type = ICMP_UNREACH;
   1257 				code = ICMP_UNREACH_SRCFAIL;
   1258 				goto bad;
   1259 			}
   1260 			ip->ip_dst = ipaddr.sin_addr;
   1261 			bcopy((caddr_t)&ia->ia_addr.sin_addr,
   1262 			    (caddr_t)(cp + off), sizeof(struct in_addr));
   1263 			cp[IPOPT_OFFSET] += sizeof(struct in_addr);
   1264 			/*
   1265 			 * Let ip_intr's mcast routing check handle mcast pkts
   1266 			 */
   1267 			forward = !IN_MULTICAST(ip->ip_dst.s_addr);
   1268 			break;
   1269 
   1270 		case IPOPT_RR:
   1271 			if (optlen < IPOPT_OFFSET + sizeof(*cp)) {
   1272 				code = &cp[IPOPT_OLEN] - (u_char *)ip;
   1273 				goto bad;
   1274 			}
   1275 			if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
   1276 				code = &cp[IPOPT_OFFSET] - (u_char *)ip;
   1277 				goto bad;
   1278 			}
   1279 			/*
   1280 			 * If no space remains, ignore.
   1281 			 */
   1282 			off--;			/* 0 origin */
   1283 			if ((off + sizeof(struct in_addr)) > optlen)
   1284 				break;
   1285 			bcopy((caddr_t)(&ip->ip_dst), (caddr_t)&ipaddr.sin_addr,
   1286 			    sizeof(ipaddr.sin_addr));
   1287 			/*
   1288 			 * locate outgoing interface; if we're the destination,
   1289 			 * use the incoming interface (should be same).
   1290 			 */
   1291 			if ((ia = ifatoia(ifa_ifwithaddr(sintosa(&ipaddr))))
   1292 			    == NULL &&
   1293 			    (ia = ip_rtaddr(ipaddr.sin_addr)) == NULL) {
   1294 				type = ICMP_UNREACH;
   1295 				code = ICMP_UNREACH_HOST;
   1296 				goto bad;
   1297 			}
   1298 			bcopy((caddr_t)&ia->ia_addr.sin_addr,
   1299 			    (caddr_t)(cp + off), sizeof(struct in_addr));
   1300 			cp[IPOPT_OFFSET] += sizeof(struct in_addr);
   1301 			break;
   1302 
   1303 		case IPOPT_TS:
   1304 			code = cp - (u_char *)ip;
   1305 			ipt = (struct ip_timestamp *)cp;
   1306 			if (ipt->ipt_len < 4 || ipt->ipt_len > 40) {
   1307 				code = (u_char *)&ipt->ipt_len - (u_char *)ip;
   1308 				goto bad;
   1309 			}
   1310 			if (ipt->ipt_ptr < 5) {
   1311 				code = (u_char *)&ipt->ipt_ptr - (u_char *)ip;
   1312 				goto bad;
   1313 			}
   1314 			if (ipt->ipt_ptr > ipt->ipt_len - sizeof (int32_t)) {
   1315 				if (++ipt->ipt_oflw == 0) {
   1316 					code = (u_char *)&ipt->ipt_ptr -
   1317 					    (u_char *)ip;
   1318 					goto bad;
   1319 				}
   1320 				break;
   1321 			}
   1322 			cp0 = (cp + ipt->ipt_ptr - 1);
   1323 			switch (ipt->ipt_flg) {
   1324 
   1325 			case IPOPT_TS_TSONLY:
   1326 				break;
   1327 
   1328 			case IPOPT_TS_TSANDADDR:
   1329 				if (ipt->ipt_ptr - 1 + sizeof(n_time) +
   1330 				    sizeof(struct in_addr) > ipt->ipt_len) {
   1331 					code = (u_char *)&ipt->ipt_ptr -
   1332 					    (u_char *)ip;
   1333 					goto bad;
   1334 				}
   1335 				ipaddr.sin_addr = dst;
   1336 				ia = ifatoia(ifaof_ifpforaddr(sintosa(&ipaddr),
   1337 				    m->m_pkthdr.rcvif));
   1338 				if (ia == 0)
   1339 					continue;
   1340 				bcopy(&ia->ia_addr.sin_addr,
   1341 				    cp0, sizeof(struct in_addr));
   1342 				ipt->ipt_ptr += sizeof(struct in_addr);
   1343 				break;
   1344 
   1345 			case IPOPT_TS_PRESPEC:
   1346 				if (ipt->ipt_ptr - 1 + sizeof(n_time) +
   1347 				    sizeof(struct in_addr) > ipt->ipt_len) {
   1348 					code = (u_char *)&ipt->ipt_ptr -
   1349 					    (u_char *)ip;
   1350 					goto bad;
   1351 				}
   1352 				bcopy(cp0, &ipaddr.sin_addr,
   1353 				    sizeof(struct in_addr));
   1354 				if (ifatoia(ifa_ifwithaddr(sintosa(&ipaddr)))
   1355 				    == NULL)
   1356 					continue;
   1357 				ipt->ipt_ptr += sizeof(struct in_addr);
   1358 				break;
   1359 
   1360 			default:
   1361 				/* XXX can't take &ipt->ipt_flg */
   1362 				code = (u_char *)&ipt->ipt_ptr -
   1363 				    (u_char *)ip + 1;
   1364 				goto bad;
   1365 			}
   1366 			ntime = iptime();
   1367 			cp0 = (u_char *) &ntime; /* XXX grumble, GCC... */
   1368 			bcopy(cp0, (caddr_t)cp + ipt->ipt_ptr - 1,
   1369 			    sizeof(n_time));
   1370 			ipt->ipt_ptr += sizeof(n_time);
   1371 		}
   1372 	}
   1373 	if (forward) {
   1374 		if (ip_forwsrcrt == 0) {
   1375 			type = ICMP_UNREACH;
   1376 			code = ICMP_UNREACH_SRCFAIL;
   1377 			goto bad;
   1378 		}
   1379 		ip_forward(m, 1);
   1380 		return (1);
   1381 	}
   1382 	return (0);
   1383 bad:
   1384 	icmp_error(m, type, code, 0, 0);
   1385 	ipstat.ips_badoptions++;
   1386 	return (1);
   1387 }
   1388 
   1389 /*
   1390  * Given address of next destination (final or next hop),
   1391  * return internet address info of interface to be used to get there.
   1392  */
   1393 struct in_ifaddr *
   1394 ip_rtaddr(dst)
   1395 	 struct in_addr dst;
   1396 {
   1397 	struct sockaddr_in *sin;
   1398 
   1399 	sin = satosin(&ipforward_rt.ro_dst);
   1400 
   1401 	if (ipforward_rt.ro_rt == 0 || !in_hosteq(dst, sin->sin_addr)) {
   1402 		if (ipforward_rt.ro_rt) {
   1403 			RTFREE(ipforward_rt.ro_rt);
   1404 			ipforward_rt.ro_rt = 0;
   1405 		}
   1406 		sin->sin_family = AF_INET;
   1407 		sin->sin_len = sizeof(*sin);
   1408 		sin->sin_addr = dst;
   1409 
   1410 		rtalloc(&ipforward_rt);
   1411 	}
   1412 	if (ipforward_rt.ro_rt == 0)
   1413 		return ((struct in_ifaddr *)0);
   1414 	return (ifatoia(ipforward_rt.ro_rt->rt_ifa));
   1415 }
   1416 
   1417 /*
   1418  * Save incoming source route for use in replies,
   1419  * to be picked up later by ip_srcroute if the receiver is interested.
   1420  */
   1421 void
   1422 save_rte(option, dst)
   1423 	u_char *option;
   1424 	struct in_addr dst;
   1425 {
   1426 	unsigned olen;
   1427 
   1428 	olen = option[IPOPT_OLEN];
   1429 #ifdef DIAGNOSTIC
   1430 	if (ipprintfs)
   1431 		printf("save_rte: olen %d\n", olen);
   1432 #endif /* 0 */
   1433 	if (olen > sizeof(ip_srcrt) - (1 + sizeof(dst)))
   1434 		return;
   1435 	bcopy((caddr_t)option, (caddr_t)ip_srcrt.srcopt, olen);
   1436 	ip_nhops = (olen - IPOPT_OFFSET - 1) / sizeof(struct in_addr);
   1437 	ip_srcrt.dst = dst;
   1438 }
   1439 
   1440 /*
   1441  * Retrieve incoming source route for use in replies,
   1442  * in the same form used by setsockopt.
   1443  * The first hop is placed before the options, will be removed later.
   1444  */
   1445 struct mbuf *
   1446 ip_srcroute()
   1447 {
   1448 	struct in_addr *p, *q;
   1449 	struct mbuf *m;
   1450 
   1451 	if (ip_nhops == 0)
   1452 		return ((struct mbuf *)0);
   1453 	m = m_get(M_DONTWAIT, MT_SOOPTS);
   1454 	if (m == 0)
   1455 		return ((struct mbuf *)0);
   1456 
   1457 	MCLAIM(m, &inetdomain.dom_mowner);
   1458 #define OPTSIZ	(sizeof(ip_srcrt.nop) + sizeof(ip_srcrt.srcopt))
   1459 
   1460 	/* length is (nhops+1)*sizeof(addr) + sizeof(nop + srcrt header) */
   1461 	m->m_len = ip_nhops * sizeof(struct in_addr) + sizeof(struct in_addr) +
   1462 	    OPTSIZ;
   1463 #ifdef DIAGNOSTIC
   1464 	if (ipprintfs)
   1465 		printf("ip_srcroute: nhops %d mlen %d", ip_nhops, m->m_len);
   1466 #endif
   1467 
   1468 	/*
   1469 	 * First save first hop for return route
   1470 	 */
   1471 	p = &ip_srcrt.route[ip_nhops - 1];
   1472 	*(mtod(m, struct in_addr *)) = *p--;
   1473 #ifdef DIAGNOSTIC
   1474 	if (ipprintfs)
   1475 		printf(" hops %x", ntohl(mtod(m, struct in_addr *)->s_addr));
   1476 #endif
   1477 
   1478 	/*
   1479 	 * Copy option fields and padding (nop) to mbuf.
   1480 	 */
   1481 	ip_srcrt.nop = IPOPT_NOP;
   1482 	ip_srcrt.srcopt[IPOPT_OFFSET] = IPOPT_MINOFF;
   1483 	bcopy((caddr_t)&ip_srcrt.nop,
   1484 	    mtod(m, caddr_t) + sizeof(struct in_addr), OPTSIZ);
   1485 	q = (struct in_addr *)(mtod(m, caddr_t) +
   1486 	    sizeof(struct in_addr) + OPTSIZ);
   1487 #undef OPTSIZ
   1488 	/*
   1489 	 * Record return path as an IP source route,
   1490 	 * reversing the path (pointers are now aligned).
   1491 	 */
   1492 	while (p >= ip_srcrt.route) {
   1493 #ifdef DIAGNOSTIC
   1494 		if (ipprintfs)
   1495 			printf(" %x", ntohl(q->s_addr));
   1496 #endif
   1497 		*q++ = *p--;
   1498 	}
   1499 	/*
   1500 	 * Last hop goes to final destination.
   1501 	 */
   1502 	*q = ip_srcrt.dst;
   1503 #ifdef DIAGNOSTIC
   1504 	if (ipprintfs)
   1505 		printf(" %x\n", ntohl(q->s_addr));
   1506 #endif
   1507 	return (m);
   1508 }
   1509 
   1510 /*
   1511  * Strip out IP options, at higher
   1512  * level protocol in the kernel.
   1513  * Second argument is buffer to which options
   1514  * will be moved, and return value is their length.
   1515  * XXX should be deleted; last arg currently ignored.
   1516  */
   1517 void
   1518 ip_stripoptions(m, mopt)
   1519 	struct mbuf *m;
   1520 	struct mbuf *mopt;
   1521 {
   1522 	int i;
   1523 	struct ip *ip = mtod(m, struct ip *);
   1524 	caddr_t opts;
   1525 	int olen;
   1526 
   1527 	olen = (ip->ip_hl << 2) - sizeof (struct ip);
   1528 	opts = (caddr_t)(ip + 1);
   1529 	i = m->m_len - (sizeof (struct ip) + olen);
   1530 	bcopy(opts  + olen, opts, (unsigned)i);
   1531 	m->m_len -= olen;
   1532 	if (m->m_flags & M_PKTHDR)
   1533 		m->m_pkthdr.len -= olen;
   1534 	ip->ip_len = htons(ntohs(ip->ip_len) - olen);
   1535 	ip->ip_hl = sizeof (struct ip) >> 2;
   1536 }
   1537 
   1538 const int inetctlerrmap[PRC_NCMDS] = {
   1539 	0,		0,		0,		0,
   1540 	0,		EMSGSIZE,	EHOSTDOWN,	EHOSTUNREACH,
   1541 	EHOSTUNREACH,	EHOSTUNREACH,	ECONNREFUSED,	ECONNREFUSED,
   1542 	EMSGSIZE,	EHOSTUNREACH,	0,		0,
   1543 	0,		0,		0,		0,
   1544 	ENOPROTOOPT
   1545 };
   1546 
   1547 /*
   1548  * Forward a packet.  If some error occurs return the sender
   1549  * an icmp packet.  Note we can't always generate a meaningful
   1550  * icmp message because icmp doesn't have a large enough repertoire
   1551  * of codes and types.
   1552  *
   1553  * If not forwarding, just drop the packet.  This could be confusing
   1554  * if ipforwarding was zero but some routing protocol was advancing
   1555  * us as a gateway to somewhere.  However, we must let the routing
   1556  * protocol deal with that.
   1557  *
   1558  * The srcrt parameter indicates whether the packet is being forwarded
   1559  * via a source route.
   1560  */
   1561 void
   1562 ip_forward(m, srcrt)
   1563 	struct mbuf *m;
   1564 	int srcrt;
   1565 {
   1566 	struct ip *ip = mtod(m, struct ip *);
   1567 	struct sockaddr_in *sin;
   1568 	struct rtentry *rt;
   1569 	int error, type = 0, code = 0;
   1570 	struct mbuf *mcopy;
   1571 	n_long dest;
   1572 	struct ifnet *destifp;
   1573 #ifdef IPSEC
   1574 	struct ifnet dummyifp;
   1575 #endif
   1576 
   1577 	/*
   1578 	 * We are now in the output path.
   1579 	 */
   1580 	MCLAIM(m, &ip_tx_mowner);
   1581 
   1582 	/*
   1583 	 * Clear any in-bound checksum flags for this packet.
   1584 	 */
   1585 	m->m_pkthdr.csum_flags = 0;
   1586 
   1587 	dest = 0;
   1588 #ifdef DIAGNOSTIC
   1589 	if (ipprintfs)
   1590 		printf("forward: src %2.2x dst %2.2x ttl %x\n",
   1591 		    ntohl(ip->ip_src.s_addr),
   1592 		    ntohl(ip->ip_dst.s_addr), ip->ip_ttl);
   1593 #endif
   1594 	if (m->m_flags & (M_BCAST|M_MCAST) || in_canforward(ip->ip_dst) == 0) {
   1595 		ipstat.ips_cantforward++;
   1596 		m_freem(m);
   1597 		return;
   1598 	}
   1599 	if (ip->ip_ttl <= IPTTLDEC) {
   1600 		icmp_error(m, ICMP_TIMXCEED, ICMP_TIMXCEED_INTRANS, dest, 0);
   1601 		return;
   1602 	}
   1603 	ip->ip_ttl -= IPTTLDEC;
   1604 
   1605 	sin = satosin(&ipforward_rt.ro_dst);
   1606 	if ((rt = ipforward_rt.ro_rt) == 0 ||
   1607 	    !in_hosteq(ip->ip_dst, sin->sin_addr)) {
   1608 		if (ipforward_rt.ro_rt) {
   1609 			RTFREE(ipforward_rt.ro_rt);
   1610 			ipforward_rt.ro_rt = 0;
   1611 		}
   1612 		sin->sin_family = AF_INET;
   1613 		sin->sin_len = sizeof(struct sockaddr_in);
   1614 		sin->sin_addr = ip->ip_dst;
   1615 
   1616 		rtalloc(&ipforward_rt);
   1617 		if (ipforward_rt.ro_rt == 0) {
   1618 			icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, dest, 0);
   1619 			return;
   1620 		}
   1621 		rt = ipforward_rt.ro_rt;
   1622 	}
   1623 
   1624 	/*
   1625 	 * Save at most 68 bytes of the packet in case
   1626 	 * we need to generate an ICMP message to the src.
   1627 	 * Pullup to avoid sharing mbuf cluster between m and mcopy.
   1628 	 */
   1629 	mcopy = m_copym(m, 0, imin(ntohs(ip->ip_len), 68), M_DONTWAIT);
   1630 	if (mcopy)
   1631 		mcopy = m_pullup(mcopy, ip->ip_hl << 2);
   1632 
   1633 	/*
   1634 	 * If forwarding packet using same interface that it came in on,
   1635 	 * perhaps should send a redirect to sender to shortcut a hop.
   1636 	 * Only send redirect if source is sending directly to us,
   1637 	 * and if packet was not source routed (or has any options).
   1638 	 * Also, don't send redirect if forwarding using a default route
   1639 	 * or a route modified by a redirect.
   1640 	 */
   1641 	if (rt->rt_ifp == m->m_pkthdr.rcvif &&
   1642 	    (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0 &&
   1643 	    !in_nullhost(satosin(rt_key(rt))->sin_addr) &&
   1644 	    ipsendredirects && !srcrt) {
   1645 		if (rt->rt_ifa &&
   1646 		    (ip->ip_src.s_addr & ifatoia(rt->rt_ifa)->ia_subnetmask) ==
   1647 		    ifatoia(rt->rt_ifa)->ia_subnet) {
   1648 			if (rt->rt_flags & RTF_GATEWAY)
   1649 				dest = satosin(rt->rt_gateway)->sin_addr.s_addr;
   1650 			else
   1651 				dest = ip->ip_dst.s_addr;
   1652 			/*
   1653 			 * Router requirements says to only send host
   1654 			 * redirects.
   1655 			 */
   1656 			type = ICMP_REDIRECT;
   1657 			code = ICMP_REDIRECT_HOST;
   1658 #ifdef DIAGNOSTIC
   1659 			if (ipprintfs)
   1660 				printf("redirect (%d) to %x\n", code,
   1661 				    (u_int32_t)dest);
   1662 #endif
   1663 		}
   1664 	}
   1665 
   1666 #ifdef IPSEC
   1667 	/* Don't lookup socket in forwarding case */
   1668 	(void)ipsec_setsocket(m, NULL);
   1669 #endif
   1670 	error = ip_output(m, (struct mbuf *)0, &ipforward_rt,
   1671 	    (IP_FORWARDING | (ip_directedbcast ? IP_ALLOWBROADCAST : 0)), 0);
   1672 	if (error)
   1673 		ipstat.ips_cantforward++;
   1674 	else {
   1675 		ipstat.ips_forward++;
   1676 		if (type)
   1677 			ipstat.ips_redirectsent++;
   1678 		else {
   1679 			if (mcopy) {
   1680 #ifdef GATEWAY
   1681 				if (mcopy->m_flags & M_CANFASTFWD)
   1682 					ipflow_create(&ipforward_rt, mcopy);
   1683 #endif
   1684 				m_freem(mcopy);
   1685 			}
   1686 			return;
   1687 		}
   1688 	}
   1689 	if (mcopy == NULL)
   1690 		return;
   1691 	destifp = NULL;
   1692 
   1693 	switch (error) {
   1694 
   1695 	case 0:				/* forwarded, but need redirect */
   1696 		/* type, code set above */
   1697 		break;
   1698 
   1699 	case ENETUNREACH:		/* shouldn't happen, checked above */
   1700 	case EHOSTUNREACH:
   1701 	case ENETDOWN:
   1702 	case EHOSTDOWN:
   1703 	default:
   1704 		type = ICMP_UNREACH;
   1705 		code = ICMP_UNREACH_HOST;
   1706 		break;
   1707 
   1708 	case EMSGSIZE:
   1709 		type = ICMP_UNREACH;
   1710 		code = ICMP_UNREACH_NEEDFRAG;
   1711 #ifndef IPSEC
   1712 		if (ipforward_rt.ro_rt)
   1713 			destifp = ipforward_rt.ro_rt->rt_ifp;
   1714 #else
   1715 		/*
   1716 		 * If the packet is routed over IPsec tunnel, tell the
   1717 		 * originator the tunnel MTU.
   1718 		 *	tunnel MTU = if MTU - sizeof(IP) - ESP/AH hdrsiz
   1719 		 * XXX quickhack!!!
   1720 		 */
   1721 		if (ipforward_rt.ro_rt) {
   1722 			struct secpolicy *sp;
   1723 			int ipsecerror;
   1724 			size_t ipsechdr;
   1725 			struct route *ro;
   1726 
   1727 			sp = ipsec4_getpolicybyaddr(mcopy,
   1728 			    IPSEC_DIR_OUTBOUND, IP_FORWARDING,
   1729 			    &ipsecerror);
   1730 
   1731 			if (sp == NULL)
   1732 				destifp = ipforward_rt.ro_rt->rt_ifp;
   1733 			else {
   1734 				/* count IPsec header size */
   1735 				ipsechdr = ipsec4_hdrsiz(mcopy,
   1736 				    IPSEC_DIR_OUTBOUND, NULL);
   1737 
   1738 				/*
   1739 				 * find the correct route for outer IPv4
   1740 				 * header, compute tunnel MTU.
   1741 				 *
   1742 				 * XXX BUG ALERT
   1743 				 * The "dummyifp" code relies upon the fact
   1744 				 * that icmp_error() touches only ifp->if_mtu.
   1745 				 */
   1746 				/*XXX*/
   1747 				destifp = NULL;
   1748 				if (sp->req != NULL
   1749 				 && sp->req->sav != NULL
   1750 				 && sp->req->sav->sah != NULL) {
   1751 					ro = &sp->req->sav->sah->sa_route;
   1752 					if (ro->ro_rt && ro->ro_rt->rt_ifp) {
   1753 						dummyifp.if_mtu =
   1754 						    ro->ro_rt->rt_rmx.rmx_mtu ?
   1755 						    ro->ro_rt->rt_rmx.rmx_mtu :
   1756 						    ro->ro_rt->rt_ifp->if_mtu;
   1757 						dummyifp.if_mtu -= ipsechdr;
   1758 						destifp = &dummyifp;
   1759 					}
   1760 				}
   1761 
   1762 				key_freesp(sp);
   1763 			}
   1764 		}
   1765 #endif /*IPSEC*/
   1766 		ipstat.ips_cantfrag++;
   1767 		break;
   1768 
   1769 	case ENOBUFS:
   1770 #if 1
   1771 		/*
   1772 		 * a router should not generate ICMP_SOURCEQUENCH as
   1773 		 * required in RFC1812 Requirements for IP Version 4 Routers.
   1774 		 * source quench could be a big problem under DoS attacks,
   1775 		 * or if the underlying interface is rate-limited.
   1776 		 */
   1777 		if (mcopy)
   1778 			m_freem(mcopy);
   1779 		return;
   1780 #else
   1781 		type = ICMP_SOURCEQUENCH;
   1782 		code = 0;
   1783 		break;
   1784 #endif
   1785 	}
   1786 	icmp_error(mcopy, type, code, dest, destifp);
   1787 }
   1788 
   1789 void
   1790 ip_savecontrol(inp, mp, ip, m)
   1791 	struct inpcb *inp;
   1792 	struct mbuf **mp;
   1793 	struct ip *ip;
   1794 	struct mbuf *m;
   1795 {
   1796 
   1797 	if (inp->inp_socket->so_options & SO_TIMESTAMP) {
   1798 		struct timeval tv;
   1799 
   1800 		microtime(&tv);
   1801 		*mp = sbcreatecontrol((caddr_t) &tv, sizeof(tv),
   1802 		    SCM_TIMESTAMP, SOL_SOCKET);
   1803 		if (*mp)
   1804 			mp = &(*mp)->m_next;
   1805 	}
   1806 	if (inp->inp_flags & INP_RECVDSTADDR) {
   1807 		*mp = sbcreatecontrol((caddr_t) &ip->ip_dst,
   1808 		    sizeof(struct in_addr), IP_RECVDSTADDR, IPPROTO_IP);
   1809 		if (*mp)
   1810 			mp = &(*mp)->m_next;
   1811 	}
   1812 #ifdef notyet
   1813 	/*
   1814 	 * XXX
   1815 	 * Moving these out of udp_input() made them even more broken
   1816 	 * than they already were.
   1817 	 *	- fenner (at) parc.xerox.com
   1818 	 */
   1819 	/* options were tossed already */
   1820 	if (inp->inp_flags & INP_RECVOPTS) {
   1821 		*mp = sbcreatecontrol((caddr_t) opts_deleted_above,
   1822 		    sizeof(struct in_addr), IP_RECVOPTS, IPPROTO_IP);
   1823 		if (*mp)
   1824 			mp = &(*mp)->m_next;
   1825 	}
   1826 	/* ip_srcroute doesn't do what we want here, need to fix */
   1827 	if (inp->inp_flags & INP_RECVRETOPTS) {
   1828 		*mp = sbcreatecontrol((caddr_t) ip_srcroute(),
   1829 		    sizeof(struct in_addr), IP_RECVRETOPTS, IPPROTO_IP);
   1830 		if (*mp)
   1831 			mp = &(*mp)->m_next;
   1832 	}
   1833 #endif
   1834 	if (inp->inp_flags & INP_RECVIF) {
   1835 		struct sockaddr_dl sdl;
   1836 
   1837 		sdl.sdl_len = offsetof(struct sockaddr_dl, sdl_data[0]);
   1838 		sdl.sdl_family = AF_LINK;
   1839 		sdl.sdl_index = m->m_pkthdr.rcvif ?
   1840 		    m->m_pkthdr.rcvif->if_index : 0;
   1841 		sdl.sdl_nlen = sdl.sdl_alen = sdl.sdl_slen = 0;
   1842 		*mp = sbcreatecontrol((caddr_t) &sdl, sdl.sdl_len,
   1843 		    IP_RECVIF, IPPROTO_IP);
   1844 		if (*mp)
   1845 			mp = &(*mp)->m_next;
   1846 	}
   1847 }
   1848 
   1849 int
   1850 ip_sysctl(name, namelen, oldp, oldlenp, newp, newlen)
   1851 	int *name;
   1852 	u_int namelen;
   1853 	void *oldp;
   1854 	size_t *oldlenp;
   1855 	void *newp;
   1856 	size_t newlen;
   1857 {
   1858 	extern int subnetsarelocal, hostzeroisbroadcast;
   1859 
   1860 	int error, old;
   1861 
   1862 	/* All sysctl names at this level are terminal. */
   1863 	if (namelen != 1)
   1864 		return (ENOTDIR);
   1865 
   1866 	switch (name[0]) {
   1867 	case IPCTL_FORWARDING:
   1868 		return (sysctl_int(oldp, oldlenp, newp, newlen, &ipforwarding));
   1869 	case IPCTL_SENDREDIRECTS:
   1870 		return (sysctl_int(oldp, oldlenp, newp, newlen,
   1871 			&ipsendredirects));
   1872 	case IPCTL_DEFTTL:
   1873 		return (sysctl_int(oldp, oldlenp, newp, newlen, &ip_defttl));
   1874 #ifdef notyet
   1875 	case IPCTL_DEFMTU:
   1876 		return (sysctl_int(oldp, oldlenp, newp, newlen, &ip_mtu));
   1877 #endif
   1878 	case IPCTL_FORWSRCRT:
   1879 		/* Don't allow this to change in a secure environment.  */
   1880 		if (securelevel > 0)
   1881 			return (sysctl_rdint(oldp, oldlenp, newp,
   1882 			    ip_forwsrcrt));
   1883 		else
   1884 			return (sysctl_int(oldp, oldlenp, newp, newlen,
   1885 			    &ip_forwsrcrt));
   1886 	case IPCTL_DIRECTEDBCAST:
   1887 		return (sysctl_int(oldp, oldlenp, newp, newlen,
   1888 		    &ip_directedbcast));
   1889 	case IPCTL_ALLOWSRCRT:
   1890 		return (sysctl_int(oldp, oldlenp, newp, newlen,
   1891 		    &ip_allowsrcrt));
   1892 	case IPCTL_SUBNETSARELOCAL:
   1893 		return (sysctl_int(oldp, oldlenp, newp, newlen,
   1894 		    &subnetsarelocal));
   1895 	case IPCTL_MTUDISC:
   1896 		error = sysctl_int(oldp, oldlenp, newp, newlen,
   1897 		    &ip_mtudisc);
   1898 		if (error == 0 && ip_mtudisc == 0)
   1899 			rt_timer_queue_remove_all(ip_mtudisc_timeout_q, TRUE);
   1900 		return error;
   1901 	case IPCTL_ANONPORTMIN:
   1902 		old = anonportmin;
   1903 		error = sysctl_int(oldp, oldlenp, newp, newlen, &anonportmin);
   1904 		if (anonportmin >= anonportmax || anonportmin < 0
   1905 		    || anonportmin > 65535
   1906 #ifndef IPNOPRIVPORTS
   1907 		    || anonportmin < IPPORT_RESERVED
   1908 #endif
   1909 		    ) {
   1910 			anonportmin = old;
   1911 			return (EINVAL);
   1912 		}
   1913 		return (error);
   1914 	case IPCTL_ANONPORTMAX:
   1915 		old = anonportmax;
   1916 		error = sysctl_int(oldp, oldlenp, newp, newlen, &anonportmax);
   1917 		if (anonportmin >= anonportmax || anonportmax < 0
   1918 		    || anonportmax > 65535
   1919 #ifndef IPNOPRIVPORTS
   1920 		    || anonportmax < IPPORT_RESERVED
   1921 #endif
   1922 		    ) {
   1923 			anonportmax = old;
   1924 			return (EINVAL);
   1925 		}
   1926 		return (error);
   1927 	case IPCTL_MTUDISCTIMEOUT:
   1928 		old = ip_mtudisc_timeout;
   1929 		error = sysctl_int(oldp, oldlenp, newp, newlen,
   1930 		   &ip_mtudisc_timeout);
   1931 		if (ip_mtudisc_timeout < 0) {
   1932 			ip_mtudisc_timeout = old;
   1933 			return (EINVAL);
   1934 		}
   1935 		if (error == 0)
   1936 			rt_timer_queue_change(ip_mtudisc_timeout_q,
   1937 					      ip_mtudisc_timeout);
   1938 		return (error);
   1939 #ifdef GATEWAY
   1940 	case IPCTL_MAXFLOWS:
   1941 	    {
   1942 		int s;
   1943 
   1944 		error = sysctl_int(oldp, oldlenp, newp, newlen,
   1945 		   &ip_maxflows);
   1946 		s = splsoftnet();
   1947 		ipflow_reap(0);
   1948 		splx(s);
   1949 		return (error);
   1950 	    }
   1951 #endif
   1952 	case IPCTL_HOSTZEROBROADCAST:
   1953 		return (sysctl_int(oldp, oldlenp, newp, newlen,
   1954 		    &hostzeroisbroadcast));
   1955 #if NGIF > 0
   1956 	case IPCTL_GIF_TTL:
   1957 		return (sysctl_int(oldp, oldlenp, newp, newlen,
   1958 				  &ip_gif_ttl));
   1959 #endif
   1960 
   1961 #if NGRE > 0
   1962 	case IPCTL_GRE_TTL:
   1963 		return (sysctl_int(oldp, oldlenp, newp, newlen,
   1964 				  &ip_gre_ttl));
   1965 #endif
   1966 
   1967 #ifndef IPNOPRIVPORTS
   1968 	case IPCTL_LOWPORTMIN:
   1969 		old = lowportmin;
   1970 		error = sysctl_int(oldp, oldlenp, newp, newlen, &lowportmin);
   1971 		if (lowportmin >= lowportmax
   1972 		    || lowportmin > IPPORT_RESERVEDMAX
   1973 		    || lowportmin < IPPORT_RESERVEDMIN
   1974 		    ) {
   1975 			lowportmin = old;
   1976 			return (EINVAL);
   1977 		}
   1978 		return (error);
   1979 	case IPCTL_LOWPORTMAX:
   1980 		old = lowportmax;
   1981 		error = sysctl_int(oldp, oldlenp, newp, newlen, &lowportmax);
   1982 		if (lowportmin >= lowportmax
   1983 		    || lowportmax > IPPORT_RESERVEDMAX
   1984 		    || lowportmax < IPPORT_RESERVEDMIN
   1985 		    ) {
   1986 			lowportmax = old;
   1987 			return (EINVAL);
   1988 		}
   1989 		return (error);
   1990 #endif
   1991 
   1992 	case IPCTL_MAXFRAGPACKETS:
   1993 		return (sysctl_int(oldp, oldlenp, newp, newlen,
   1994 		    &ip_maxfragpackets));
   1995 
   1996 	case IPCTL_CHECKINTERFACE:
   1997 		return (sysctl_int(oldp, oldlenp, newp, newlen,
   1998 		    &ip_checkinterface));
   1999 	default:
   2000 		return (EOPNOTSUPP);
   2001 	}
   2002 	/* NOTREACHED */
   2003 }
   2004