xref: /netbsd-src/sys/netinet/ip_input.c (revision 46f5119e40af2e51998f686b2fdcc76b5488f7f3)
1 /*	$NetBSD: ip_input.c,v 1.295 2011/05/03 17:44:31 dyoung 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  *
49  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
50  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
51  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
52  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
53  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
54  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
55  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
56  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
57  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
58  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
59  * POSSIBILITY OF SUCH DAMAGE.
60  */
61 
62 /*
63  * Copyright (c) 1982, 1986, 1988, 1993
64  *	The Regents of the University of California.  All rights reserved.
65  *
66  * Redistribution and use in source and binary forms, with or without
67  * modification, are permitted provided that the following conditions
68  * are met:
69  * 1. Redistributions of source code must retain the above copyright
70  *    notice, this list of conditions and the following disclaimer.
71  * 2. Redistributions in binary form must reproduce the above copyright
72  *    notice, this list of conditions and the following disclaimer in the
73  *    documentation and/or other materials provided with the distribution.
74  * 3. Neither the name of the University nor the names of its contributors
75  *    may be used to endorse or promote products derived from this software
76  *    without specific prior written permission.
77  *
78  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
79  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
80  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
81  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
82  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
83  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
84  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
85  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
86  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
87  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
88  * SUCH DAMAGE.
89  *
90  *	@(#)ip_input.c	8.2 (Berkeley) 1/4/94
91  */
92 
93 #include <sys/cdefs.h>
94 __KERNEL_RCSID(0, "$NetBSD: ip_input.c,v 1.295 2011/05/03 17:44:31 dyoung Exp $");
95 
96 #include "opt_inet.h"
97 #include "opt_compat_netbsd.h"
98 #include "opt_gateway.h"
99 #include "opt_pfil_hooks.h"
100 #include "opt_ipsec.h"
101 #include "opt_mrouting.h"
102 #include "opt_mbuftrace.h"
103 #include "opt_inet_csum.h"
104 
105 #include <sys/param.h>
106 #include <sys/systm.h>
107 #include <sys/mbuf.h>
108 #include <sys/domain.h>
109 #include <sys/protosw.h>
110 #include <sys/socket.h>
111 #include <sys/socketvar.h>
112 #include <sys/errno.h>
113 #include <sys/time.h>
114 #include <sys/kernel.h>
115 #include <sys/pool.h>
116 #include <sys/sysctl.h>
117 #include <sys/kauth.h>
118 
119 #include <net/if.h>
120 #include <net/if_dl.h>
121 #include <net/route.h>
122 #include <net/pfil.h>
123 
124 #include <netinet/in.h>
125 #include <netinet/in_systm.h>
126 #include <netinet/ip.h>
127 #include <netinet/in_pcb.h>
128 #include <netinet/in_proto.h>
129 #include <netinet/in_var.h>
130 #include <netinet/ip_var.h>
131 #include <netinet/ip_private.h>
132 #include <netinet/ip_icmp.h>
133 /* just for gif_ttl */
134 #include <netinet/in_gif.h>
135 #include "gif.h"
136 #include <net/if_gre.h>
137 #include "gre.h"
138 
139 #ifdef MROUTING
140 #include <netinet/ip_mroute.h>
141 #endif
142 
143 #ifdef IPSEC
144 #include <netinet6/ipsec.h>
145 #include <netinet6/ipsec_private.h>
146 #include <netkey/key.h>
147 #endif
148 #ifdef FAST_IPSEC
149 #include <netipsec/ipsec.h>
150 #include <netipsec/key.h>
151 #endif	/* FAST_IPSEC*/
152 
153 #ifndef	IPFORWARDING
154 #ifdef GATEWAY
155 #define	IPFORWARDING	1	/* forward IP packets not for us */
156 #else /* GATEWAY */
157 #define	IPFORWARDING	0	/* don't forward IP packets not for us */
158 #endif /* GATEWAY */
159 #endif /* IPFORWARDING */
160 #ifndef	IPSENDREDIRECTS
161 #define	IPSENDREDIRECTS	1
162 #endif
163 #ifndef IPFORWSRCRT
164 #define	IPFORWSRCRT	1	/* forward source-routed packets */
165 #endif
166 #ifndef IPALLOWSRCRT
167 #define	IPALLOWSRCRT	1	/* allow source-routed packets */
168 #endif
169 #ifndef IPMTUDISC
170 #define IPMTUDISC	1
171 #endif
172 #ifndef IPMTUDISCTIMEOUT
173 #define IPMTUDISCTIMEOUT (10 * 60)	/* as per RFC 1191 */
174 #endif
175 
176 #ifdef COMPAT_50
177 #include <compat/sys/time.h>
178 #include <compat/sys/socket.h>
179 #endif
180 
181 /*
182  * Note: DIRECTED_BROADCAST is handled this way so that previous
183  * configuration using this option will Just Work.
184  */
185 #ifndef IPDIRECTEDBCAST
186 #ifdef DIRECTED_BROADCAST
187 #define IPDIRECTEDBCAST	1
188 #else
189 #define	IPDIRECTEDBCAST	0
190 #endif /* DIRECTED_BROADCAST */
191 #endif /* IPDIRECTEDBCAST */
192 int	ipforwarding = IPFORWARDING;
193 int	ipsendredirects = IPSENDREDIRECTS;
194 int	ip_defttl = IPDEFTTL;
195 int	ip_forwsrcrt = IPFORWSRCRT;
196 int	ip_directedbcast = IPDIRECTEDBCAST;
197 int	ip_allowsrcrt = IPALLOWSRCRT;
198 int	ip_mtudisc = IPMTUDISC;
199 int	ip_mtudisc_timeout = IPMTUDISCTIMEOUT;
200 #ifdef DIAGNOSTIC
201 int	ipprintfs = 0;
202 #endif
203 
204 int	ip_do_randomid = 0;
205 
206 /*
207  * XXX - Setting ip_checkinterface mostly implements the receive side of
208  * the Strong ES model described in RFC 1122, but since the routing table
209  * and transmit implementation do not implement the Strong ES model,
210  * setting this to 1 results in an odd hybrid.
211  *
212  * XXX - ip_checkinterface currently must be disabled if you use ipnat
213  * to translate the destination address to another local interface.
214  *
215  * XXX - ip_checkinterface must be disabled if you add IP aliases
216  * to the loopback interface instead of the interface where the
217  * packets for those addresses are received.
218  */
219 int	ip_checkinterface = 0;
220 
221 
222 struct rttimer_queue *ip_mtudisc_timeout_q = NULL;
223 
224 u_long	in_ifaddrhash;				/* size of hash table - 1 */
225 int	in_ifaddrentries;			/* total number of addrs */
226 struct in_ifaddrhead in_ifaddrhead;
227 struct	in_ifaddrhashhead *in_ifaddrhashtbl;
228 u_long	in_multihash;				/* size of hash table - 1 */
229 int	in_multientries;			/* total number of addrs */
230 struct	in_multihashhead *in_multihashtbl;
231 struct	ifqueue ipintrq;
232 
233 ipid_state_t *		ip_ids;
234 uint16_t ip_id;
235 
236 percpu_t *ipstat_percpu;
237 
238 #ifdef PFIL_HOOKS
239 struct pfil_head inet_pfil_hook;
240 #endif
241 
242 struct pool inmulti_pool;
243 
244 #ifdef INET_CSUM_COUNTERS
245 #include <sys/device.h>
246 
247 struct evcnt ip_hwcsum_bad = EVCNT_INITIALIZER(EVCNT_TYPE_MISC,
248     NULL, "inet", "hwcsum bad");
249 struct evcnt ip_hwcsum_ok = EVCNT_INITIALIZER(EVCNT_TYPE_MISC,
250     NULL, "inet", "hwcsum ok");
251 struct evcnt ip_swcsum = EVCNT_INITIALIZER(EVCNT_TYPE_MISC,
252     NULL, "inet", "swcsum");
253 
254 #define	INET_CSUM_COUNTER_INCR(ev)	(ev)->ev_count++
255 
256 EVCNT_ATTACH_STATIC(ip_hwcsum_bad);
257 EVCNT_ATTACH_STATIC(ip_hwcsum_ok);
258 EVCNT_ATTACH_STATIC(ip_swcsum);
259 
260 #else
261 
262 #define	INET_CSUM_COUNTER_INCR(ev)	/* nothing */
263 
264 #endif /* INET_CSUM_COUNTERS */
265 
266 /*
267  * We need to save the IP options in case a protocol wants to respond
268  * to an incoming packet over the same route if the packet got here
269  * using IP source routing.  This allows connection establishment and
270  * maintenance when the remote end is on a network that is not known
271  * to us.
272  */
273 int	ip_nhops = 0;
274 static	struct ip_srcrt {
275 	struct	in_addr dst;			/* final destination */
276 	char	nop;				/* one NOP to align */
277 	char	srcopt[IPOPT_OFFSET + 1];	/* OPTVAL, OLEN and OFFSET */
278 	struct	in_addr route[MAX_IPOPTLEN/sizeof(struct in_addr)];
279 } ip_srcrt;
280 
281 static int ip_drainwanted;
282 
283 static void save_rte(u_char *, struct in_addr);
284 
285 #ifdef MBUFTRACE
286 struct mowner ip_rx_mowner = MOWNER_INIT("internet", "rx");
287 struct mowner ip_tx_mowner = MOWNER_INIT("internet", "tx");
288 #endif
289 
290 static void sysctl_net_inet_ip_setup(struct sysctllog **);
291 
292 /*
293  * IP initialization: fill in IP protocol switch table.
294  * All protocols not implemented in kernel go to raw IP protocol handler.
295  */
296 void
297 ip_init(void)
298 {
299 	const struct protosw *pr;
300 	int i;
301 
302 	sysctl_net_inet_ip_setup(NULL);
303 
304 	pool_init(&inmulti_pool, sizeof(struct in_multi), 0, 0, 0, "inmltpl",
305 	    NULL, IPL_SOFTNET);
306 
307 	pr = pffindproto(PF_INET, IPPROTO_RAW, SOCK_RAW);
308 	if (pr == 0)
309 		panic("ip_init");
310 	for (i = 0; i < IPPROTO_MAX; i++)
311 		ip_protox[i] = pr - inetsw;
312 	for (pr = inetdomain.dom_protosw;
313 	    pr < inetdomain.dom_protoswNPROTOSW; pr++)
314 		if (pr->pr_domain->dom_family == PF_INET &&
315 		    pr->pr_protocol && pr->pr_protocol != IPPROTO_RAW)
316 			ip_protox[pr->pr_protocol] = pr - inetsw;
317 
318 	ip_reass_init();
319 
320 	ip_ids = ip_id_init();
321 	ip_id = time_second & 0xfffff;
322 
323 	ipintrq.ifq_maxlen = IFQ_MAXLEN;
324 
325 	TAILQ_INIT(&in_ifaddrhead);
326 	in_ifaddrhashtbl = hashinit(IN_IFADDR_HASH_SIZE, HASH_LIST, true,
327 	    &in_ifaddrhash);
328 	in_multihashtbl = hashinit(IN_IFADDR_HASH_SIZE, HASH_LIST, true,
329 	    &in_multihash);
330 	ip_mtudisc_timeout_q = rt_timer_queue_create(ip_mtudisc_timeout);
331 #ifdef GATEWAY
332 	ipflow_init(ip_hashsize);
333 #endif
334 
335 #ifdef PFIL_HOOKS
336 	/* Register our Packet Filter hook. */
337 	inet_pfil_hook.ph_type = PFIL_TYPE_AF;
338 	inet_pfil_hook.ph_af   = AF_INET;
339 	i = pfil_head_register(&inet_pfil_hook);
340 	if (i != 0)
341 		printf("ip_init: WARNING: unable to register pfil hook, "
342 		    "error %d\n", i);
343 #endif /* PFIL_HOOKS */
344 
345 #ifdef MBUFTRACE
346 	MOWNER_ATTACH(&ip_tx_mowner);
347 	MOWNER_ATTACH(&ip_rx_mowner);
348 #endif /* MBUFTRACE */
349 
350 	ipstat_percpu = percpu_alloc(sizeof(uint64_t) * IP_NSTATS);
351 }
352 
353 struct	sockaddr_in ipaddr = {
354 	.sin_len = sizeof(ipaddr),
355 	.sin_family = AF_INET,
356 };
357 struct	route ipforward_rt;
358 
359 /*
360  * IP software interrupt routine
361  */
362 void
363 ipintr(void)
364 {
365 	int s;
366 	struct mbuf *m;
367 	struct ifqueue lcl_intrq;
368 
369 	memset(&lcl_intrq, 0, sizeof(lcl_intrq));
370 
371 	mutex_enter(softnet_lock);
372 	KERNEL_LOCK(1, NULL);
373 	if (!IF_IS_EMPTY(&ipintrq)) {
374 		s = splnet();
375 
376 		/* Take existing queue onto stack */
377 		lcl_intrq = ipintrq;
378 
379 		/* Zero out global queue, preserving maxlen and drops */
380 		ipintrq.ifq_head = NULL;
381 		ipintrq.ifq_tail = NULL;
382 		ipintrq.ifq_len = 0;
383 		ipintrq.ifq_maxlen = lcl_intrq.ifq_maxlen;
384 		ipintrq.ifq_drops = lcl_intrq.ifq_drops;
385 
386 		splx(s);
387 	}
388 	KERNEL_UNLOCK_ONE(NULL);
389 	while (!IF_IS_EMPTY(&lcl_intrq)) {
390 		IF_DEQUEUE(&lcl_intrq, m);
391 		if (m == NULL)
392 			break;
393 		ip_input(m);
394 	}
395 	mutex_exit(softnet_lock);
396 }
397 
398 /*
399  * Ip input routine.  Checksum and byte swap header.  If fragmented
400  * try to reassemble.  Process options.  Pass to next level.
401  */
402 void
403 ip_input(struct mbuf *m)
404 {
405 	struct ip *ip = NULL;
406 	struct in_ifaddr *ia;
407 	struct ifaddr *ifa;
408 	int hlen = 0, len;
409 	int downmatch;
410 	int checkif;
411 	int srcrt = 0;
412 #ifdef FAST_IPSEC
413 	struct m_tag *mtag;
414 	struct tdb_ident *tdbi;
415 	struct secpolicy *sp;
416 	int error, s;
417 #endif /* FAST_IPSEC */
418 
419 	MCLAIM(m, &ip_rx_mowner);
420 	KASSERT((m->m_flags & M_PKTHDR) != 0);
421 
422 	/*
423 	 * If no IP addresses have been set yet but the interfaces
424 	 * are receiving, can't do anything with incoming packets yet.
425 	 */
426 	if (TAILQ_FIRST(&in_ifaddrhead) == 0)
427 		goto bad;
428 	IP_STATINC(IP_STAT_TOTAL);
429 	/*
430 	 * If the IP header is not aligned, slurp it up into a new
431 	 * mbuf with space for link headers, in the event we forward
432 	 * it.  Otherwise, if it is aligned, make sure the entire
433 	 * base IP header is in the first mbuf of the chain.
434 	 */
435 	if (IP_HDR_ALIGNED_P(mtod(m, void *)) == 0) {
436 		if ((m = m_copyup(m, sizeof(struct ip),
437 				  (max_linkhdr + 3) & ~3)) == NULL) {
438 			/* XXXJRT new stat, please */
439 			IP_STATINC(IP_STAT_TOOSMALL);
440 			return;
441 		}
442 	} else if (__predict_false(m->m_len < sizeof (struct ip))) {
443 		if ((m = m_pullup(m, sizeof (struct ip))) == NULL) {
444 			IP_STATINC(IP_STAT_TOOSMALL);
445 			return;
446 		}
447 	}
448 	ip = mtod(m, struct ip *);
449 	if (ip->ip_v != IPVERSION) {
450 		IP_STATINC(IP_STAT_BADVERS);
451 		goto bad;
452 	}
453 	hlen = ip->ip_hl << 2;
454 	if (hlen < sizeof(struct ip)) {	/* minimum header length */
455 		IP_STATINC(IP_STAT_BADHLEN);
456 		goto bad;
457 	}
458 	if (hlen > m->m_len) {
459 		if ((m = m_pullup(m, hlen)) == 0) {
460 			IP_STATINC(IP_STAT_BADHLEN);
461 			return;
462 		}
463 		ip = mtod(m, struct ip *);
464 	}
465 
466 	/*
467 	 * RFC1122: packets with a multicast source address are
468 	 * not allowed.
469 	 */
470 	if (IN_MULTICAST(ip->ip_src.s_addr)) {
471 		IP_STATINC(IP_STAT_BADADDR);
472 		goto bad;
473 	}
474 
475 	/* 127/8 must not appear on wire - RFC1122 */
476 	if ((ntohl(ip->ip_dst.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET ||
477 	    (ntohl(ip->ip_src.s_addr) >> IN_CLASSA_NSHIFT) == IN_LOOPBACKNET) {
478 		if ((m->m_pkthdr.rcvif->if_flags & IFF_LOOPBACK) == 0) {
479 			IP_STATINC(IP_STAT_BADADDR);
480 			goto bad;
481 		}
482 	}
483 
484 	switch (m->m_pkthdr.csum_flags &
485 		((m->m_pkthdr.rcvif->if_csum_flags_rx & M_CSUM_IPv4) |
486 		 M_CSUM_IPv4_BAD)) {
487 	case M_CSUM_IPv4|M_CSUM_IPv4_BAD:
488 		INET_CSUM_COUNTER_INCR(&ip_hwcsum_bad);
489 		goto badcsum;
490 
491 	case M_CSUM_IPv4:
492 		/* Checksum was okay. */
493 		INET_CSUM_COUNTER_INCR(&ip_hwcsum_ok);
494 		break;
495 
496 	default:
497 		/*
498 		 * Must compute it ourselves.  Maybe skip checksum on
499 		 * loopback interfaces.
500 		 */
501 		if (__predict_true(!(m->m_pkthdr.rcvif->if_flags &
502 				     IFF_LOOPBACK) || ip_do_loopback_cksum)) {
503 			INET_CSUM_COUNTER_INCR(&ip_swcsum);
504 			if (in_cksum(m, hlen) != 0)
505 				goto badcsum;
506 		}
507 		break;
508 	}
509 
510 	/* Retrieve the packet length. */
511 	len = ntohs(ip->ip_len);
512 
513 	/*
514 	 * Check for additional length bogosity
515 	 */
516 	if (len < hlen) {
517 		IP_STATINC(IP_STAT_BADLEN);
518 		goto bad;
519 	}
520 
521 	/*
522 	 * Check that the amount of data in the buffers
523 	 * is as at least much as the IP header would have us expect.
524 	 * Trim mbufs if longer than we expect.
525 	 * Drop packet if shorter than we expect.
526 	 */
527 	if (m->m_pkthdr.len < len) {
528 		IP_STATINC(IP_STAT_TOOSHORT);
529 		goto bad;
530 	}
531 	if (m->m_pkthdr.len > len) {
532 		if (m->m_len == m->m_pkthdr.len) {
533 			m->m_len = len;
534 			m->m_pkthdr.len = len;
535 		} else
536 			m_adj(m, len - m->m_pkthdr.len);
537 	}
538 
539 #if defined(IPSEC)
540 	/* ipflow (IP fast forwarding) is not compatible with IPsec. */
541 	m->m_flags &= ~M_CANFASTFWD;
542 #else
543 	/*
544 	 * Assume that we can create a fast-forward IP flow entry
545 	 * based on this packet.
546 	 */
547 	m->m_flags |= M_CANFASTFWD;
548 #endif
549 
550 #ifdef PFIL_HOOKS
551 	/*
552 	 * Run through list of hooks for input packets.  If there are any
553 	 * filters which require that additional packets in the flow are
554 	 * not fast-forwarded, they must clear the M_CANFASTFWD flag.
555 	 * Note that filters must _never_ set this flag, as another filter
556 	 * in the list may have previously cleared it.
557 	 */
558 	/*
559 	 * let ipfilter look at packet on the wire,
560 	 * not the decapsulated packet.
561 	 */
562 #ifdef IPSEC
563 	if (!ipsec_getnhist(m))
564 #elif defined(FAST_IPSEC)
565 	if (!ipsec_indone(m))
566 #else
567 	if (1)
568 #endif
569 	{
570 		struct in_addr odst;
571 
572 		odst = ip->ip_dst;
573 		if (pfil_run_hooks(&inet_pfil_hook, &m, m->m_pkthdr.rcvif,
574 		    PFIL_IN) != 0)
575 			return;
576 		if (m == NULL)
577 			return;
578 		ip = mtod(m, struct ip *);
579 		hlen = ip->ip_hl << 2;
580 		/*
581 		 * XXX The setting of "srcrt" here is to prevent ip_forward()
582 		 * from generating ICMP redirects for packets that have
583 		 * been redirected by a hook back out on to the same LAN that
584 		 * they came from and is not an indication that the packet
585 		 * is being inffluenced by source routing options.  This
586 		 * allows things like
587 		 * "rdr tlp0 0/0 port 80 -> 1.1.1.200 3128 tcp"
588 		 * where tlp0 is both on the 1.1.1.0/24 network and is the
589 		 * default route for hosts on 1.1.1.0/24.  Of course this
590 		 * also requires a "map tlp0 ..." to complete the story.
591 		 * One might argue whether or not this kind of network config.
592 		 * should be supported in this manner...
593 		 */
594 		srcrt = (odst.s_addr != ip->ip_dst.s_addr);
595 	}
596 #endif /* PFIL_HOOKS */
597 
598 #ifdef ALTQ
599 	/* XXX Temporary until ALTQ is changed to use a pfil hook */
600 	if (altq_input != NULL && (*altq_input)(m, AF_INET) == 0) {
601 		/* packet dropped by traffic conditioner */
602 		return;
603 	}
604 #endif
605 
606 	/*
607 	 * Process options and, if not destined for us,
608 	 * ship it on.  ip_dooptions returns 1 when an
609 	 * error was detected (causing an icmp message
610 	 * to be sent and the original packet to be freed).
611 	 */
612 	ip_nhops = 0;		/* for source routed packets */
613 	if (hlen > sizeof (struct ip) && ip_dooptions(m))
614 		return;
615 
616 	/*
617 	 * Enable a consistency check between the destination address
618 	 * and the arrival interface for a unicast packet (the RFC 1122
619 	 * strong ES model) if IP forwarding is disabled and the packet
620 	 * is not locally generated.
621 	 *
622 	 * XXX - Checking also should be disabled if the destination
623 	 * address is ipnat'ed to a different interface.
624 	 *
625 	 * XXX - Checking is incompatible with IP aliases added
626 	 * to the loopback interface instead of the interface where
627 	 * the packets are received.
628 	 *
629 	 * XXX - We need to add a per ifaddr flag for this so that
630 	 * we get finer grain control.
631 	 */
632 	checkif = ip_checkinterface && (ipforwarding == 0) &&
633 	    (m->m_pkthdr.rcvif != NULL) &&
634 	    ((m->m_pkthdr.rcvif->if_flags & IFF_LOOPBACK) == 0);
635 
636 	/*
637 	 * Check our list of addresses, to see if the packet is for us.
638 	 *
639 	 * Traditional 4.4BSD did not consult IFF_UP at all.
640 	 * The behavior here is to treat addresses on !IFF_UP interface
641 	 * as not mine.
642 	 */
643 	downmatch = 0;
644 	LIST_FOREACH(ia, &IN_IFADDR_HASH(ip->ip_dst.s_addr), ia_hash) {
645 		if (in_hosteq(ia->ia_addr.sin_addr, ip->ip_dst)) {
646 			if (checkif && ia->ia_ifp != m->m_pkthdr.rcvif)
647 				continue;
648 			if ((ia->ia_ifp->if_flags & IFF_UP) != 0)
649 				break;
650 			else
651 				downmatch++;
652 		}
653 	}
654 	if (ia != NULL)
655 		goto ours;
656 	if (m->m_pkthdr.rcvif && m->m_pkthdr.rcvif->if_flags & IFF_BROADCAST) {
657 		IFADDR_FOREACH(ifa, m->m_pkthdr.rcvif) {
658 			if (ifa->ifa_addr->sa_family != AF_INET)
659 				continue;
660 			ia = ifatoia(ifa);
661 			if (in_hosteq(ip->ip_dst, ia->ia_broadaddr.sin_addr) ||
662 			    in_hosteq(ip->ip_dst, ia->ia_netbroadcast) ||
663 			    /*
664 			     * Look for all-0's host part (old broadcast addr),
665 			     * either for subnet or net.
666 			     */
667 			    ip->ip_dst.s_addr == ia->ia_subnet ||
668 			    ip->ip_dst.s_addr == ia->ia_net)
669 				goto ours;
670 			/*
671 			 * An interface with IP address zero accepts
672 			 * all packets that arrive on that interface.
673 			 */
674 			if (in_nullhost(ia->ia_addr.sin_addr))
675 				goto ours;
676 		}
677 	}
678 	if (IN_MULTICAST(ip->ip_dst.s_addr)) {
679 		struct in_multi *inm;
680 #ifdef MROUTING
681 		extern struct socket *ip_mrouter;
682 
683 		if (ip_mrouter) {
684 			/*
685 			 * If we are acting as a multicast router, all
686 			 * incoming multicast packets are passed to the
687 			 * kernel-level multicast forwarding function.
688 			 * The packet is returned (relatively) intact; if
689 			 * ip_mforward() returns a non-zero value, the packet
690 			 * must be discarded, else it may be accepted below.
691 			 *
692 			 * (The IP ident field is put in the same byte order
693 			 * as expected when ip_mforward() is called from
694 			 * ip_output().)
695 			 */
696 			if (ip_mforward(m, m->m_pkthdr.rcvif) != 0) {
697 				IP_STATINC(IP_STAT_CANTFORWARD);
698 				m_freem(m);
699 				return;
700 			}
701 
702 			/*
703 			 * The process-level routing demon needs to receive
704 			 * all multicast IGMP packets, whether or not this
705 			 * host belongs to their destination groups.
706 			 */
707 			if (ip->ip_p == IPPROTO_IGMP)
708 				goto ours;
709 			IP_STATINC(IP_STAT_CANTFORWARD);
710 		}
711 #endif
712 		/*
713 		 * See if we belong to the destination multicast group on the
714 		 * arrival interface.
715 		 */
716 		IN_LOOKUP_MULTI(ip->ip_dst, m->m_pkthdr.rcvif, inm);
717 		if (inm == NULL) {
718 			IP_STATINC(IP_STAT_CANTFORWARD);
719 			m_freem(m);
720 			return;
721 		}
722 		goto ours;
723 	}
724 	if (ip->ip_dst.s_addr == INADDR_BROADCAST ||
725 	    in_nullhost(ip->ip_dst))
726 		goto ours;
727 
728 	/*
729 	 * Not for us; forward if possible and desirable.
730 	 */
731 	if (ipforwarding == 0) {
732 		IP_STATINC(IP_STAT_CANTFORWARD);
733 		m_freem(m);
734 	} else {
735 		/*
736 		 * If ip_dst matched any of my address on !IFF_UP interface,
737 		 * and there's no IFF_UP interface that matches ip_dst,
738 		 * send icmp unreach.  Forwarding it will result in in-kernel
739 		 * forwarding loop till TTL goes to 0.
740 		 */
741 		if (downmatch) {
742 			icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_HOST, 0, 0);
743 			IP_STATINC(IP_STAT_CANTFORWARD);
744 			return;
745 		}
746 #ifdef IPSEC
747 		if (ipsec4_in_reject(m, NULL)) {
748 			IPSEC_STATINC(IPSEC_STAT_IN_POLVIO);
749 			goto bad;
750 		}
751 #endif
752 #ifdef FAST_IPSEC
753 		mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
754 		s = splsoftnet();
755 		if (mtag != NULL) {
756 			tdbi = (struct tdb_ident *)(mtag + 1);
757 			sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
758 		} else {
759 			sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
760 						   IP_FORWARDING, &error);
761 		}
762 		if (sp == NULL) {	/* NB: can happen if error */
763 			splx(s);
764 			/*XXX error stat???*/
765 			DPRINTF(("ip_input: no SP for forwarding\n"));	/*XXX*/
766 			goto bad;
767 		}
768 
769 		/*
770 		 * Check security policy against packet attributes.
771 		 */
772 		error = ipsec_in_reject(sp, m);
773 		KEY_FREESP(&sp);
774 		splx(s);
775 		if (error) {
776 			IP_STATINC(IP_STAT_CANTFORWARD);
777 			goto bad;
778 		}
779 
780 		/*
781 		 * Peek at the outbound SP for this packet to determine if
782 		 * it's a Fast Forward candidate.
783 		 */
784 		mtag = m_tag_find(m, PACKET_TAG_IPSEC_PENDING_TDB, NULL);
785 		if (mtag != NULL)
786 			m->m_flags &= ~M_CANFASTFWD;
787 		else {
788 			s = splsoftnet();
789 			sp = ipsec4_checkpolicy(m, IPSEC_DIR_OUTBOUND,
790 			    (IP_FORWARDING |
791 			     (ip_directedbcast ? IP_ALLOWBROADCAST : 0)),
792 			    &error, NULL);
793 			if (sp != NULL) {
794 				m->m_flags &= ~M_CANFASTFWD;
795 				KEY_FREESP(&sp);
796 			}
797 			splx(s);
798 		}
799 #endif	/* FAST_IPSEC */
800 
801 		ip_forward(m, srcrt);
802 	}
803 	return;
804 
805 ours:
806 	/*
807 	 * If offset or IP_MF are set, must reassemble.
808 	 */
809 	if (ip->ip_off & ~htons(IP_DF|IP_RF)) {
810 		/*
811 		 * Pass to IP reassembly mechanism.
812 		 */
813 		if (ip_reass_packet(&m, ip) != 0) {
814 			/* Failed; invalid fragment(s) or packet. */
815 			goto bad;
816 		}
817 		if (m == NULL) {
818 			/* More fragments should come; silently return. */
819 			return;
820 		}
821 		/*
822 		 * Reassembly is done, we have the final packet.
823 		 * Updated cached data in local variable(s).
824 		 */
825 		ip = mtod(m, struct ip *);
826 		hlen = ip->ip_hl << 2;
827 	}
828 
829 #if defined(IPSEC)
830 	/*
831 	 * enforce IPsec policy checking if we are seeing last header.
832 	 * note that we do not visit this with protocols with pcb layer
833 	 * code - like udp/tcp/raw ip.
834 	 */
835 	if ((inetsw[ip_protox[ip->ip_p]].pr_flags & PR_LASTHDR) != 0 &&
836 	    ipsec4_in_reject(m, NULL)) {
837 		IPSEC_STATINC(IPSEC_STAT_IN_POLVIO);
838 		goto bad;
839 	}
840 #endif
841 #ifdef FAST_IPSEC
842 	/*
843 	 * enforce IPsec policy checking if we are seeing last header.
844 	 * note that we do not visit this with protocols with pcb layer
845 	 * code - like udp/tcp/raw ip.
846 	 */
847 	if ((inetsw[ip_protox[ip->ip_p]].pr_flags & PR_LASTHDR) != 0) {
848 		/*
849 		 * Check if the packet has already had IPsec processing
850 		 * done.  If so, then just pass it along.  This tag gets
851 		 * set during AH, ESP, etc. input handling, before the
852 		 * packet is returned to the ip input queue for delivery.
853 		 */
854 		mtag = m_tag_find(m, PACKET_TAG_IPSEC_IN_DONE, NULL);
855 		s = splsoftnet();
856 		if (mtag != NULL) {
857 			tdbi = (struct tdb_ident *)(mtag + 1);
858 			sp = ipsec_getpolicy(tdbi, IPSEC_DIR_INBOUND);
859 		} else {
860 			sp = ipsec_getpolicybyaddr(m, IPSEC_DIR_INBOUND,
861 						   IP_FORWARDING, &error);
862 		}
863 		if (sp != NULL) {
864 			/*
865 			 * Check security policy against packet attributes.
866 			 */
867 			error = ipsec_in_reject(sp, m);
868 			KEY_FREESP(&sp);
869 		} else {
870 			/* XXX error stat??? */
871 			error = EINVAL;
872 DPRINTF(("ip_input: no SP, packet discarded\n"));/*XXX*/
873 		}
874 		splx(s);
875 		if (error)
876 			goto bad;
877 	}
878 #endif /* FAST_IPSEC */
879 
880 	/*
881 	 * Switch out to protocol's input routine.
882 	 */
883 #if IFA_STATS
884 	if (ia && ip)
885 		ia->ia_ifa.ifa_data.ifad_inbytes += ntohs(ip->ip_len);
886 #endif
887 	IP_STATINC(IP_STAT_DELIVERED);
888     {
889 	int off = hlen, nh = ip->ip_p;
890 
891 	(*inetsw[ip_protox[nh]].pr_input)(m, off, nh);
892 	return;
893     }
894 bad:
895 	m_freem(m);
896 	return;
897 
898 badcsum:
899 	IP_STATINC(IP_STAT_BADSUM);
900 	m_freem(m);
901 }
902 
903 /*
904  * IP timer processing.
905  */
906 void
907 ip_slowtimo(void)
908 {
909 
910 	mutex_enter(softnet_lock);
911 	KERNEL_LOCK(1, NULL);
912 
913 	ip_reass_slowtimo();
914 
915 	KERNEL_UNLOCK_ONE(NULL);
916 	mutex_exit(softnet_lock);
917 }
918 
919 /*
920  * IP drain processing.
921  */
922 void
923 ip_drain(void)
924 {
925 
926 	KERNEL_LOCK(1, NULL);
927 	ip_reass_drain();
928 	KERNEL_UNLOCK_ONE(NULL);
929 }
930 
931 /*
932  * Do option processing on a datagram,
933  * possibly discarding it if bad options are encountered,
934  * or forwarding it if source-routed.
935  * Returns 1 if packet has been forwarded/freed,
936  * 0 if the packet should be processed further.
937  */
938 int
939 ip_dooptions(struct mbuf *m)
940 {
941 	struct ip *ip = mtod(m, struct ip *);
942 	u_char *cp, *cp0;
943 	struct ip_timestamp *ipt;
944 	struct in_ifaddr *ia;
945 	int opt, optlen, cnt, off, code, type = ICMP_PARAMPROB, forward = 0;
946 	struct in_addr dst;
947 	n_time ntime;
948 
949 	dst = ip->ip_dst;
950 	cp = (u_char *)(ip + 1);
951 	cnt = (ip->ip_hl << 2) - sizeof (struct ip);
952 	for (; cnt > 0; cnt -= optlen, cp += optlen) {
953 		opt = cp[IPOPT_OPTVAL];
954 		if (opt == IPOPT_EOL)
955 			break;
956 		if (opt == IPOPT_NOP)
957 			optlen = 1;
958 		else {
959 			if (cnt < IPOPT_OLEN + sizeof(*cp)) {
960 				code = &cp[IPOPT_OLEN] - (u_char *)ip;
961 				goto bad;
962 			}
963 			optlen = cp[IPOPT_OLEN];
964 			if (optlen < IPOPT_OLEN + sizeof(*cp) || optlen > cnt) {
965 				code = &cp[IPOPT_OLEN] - (u_char *)ip;
966 				goto bad;
967 			}
968 		}
969 		switch (opt) {
970 
971 		default:
972 			break;
973 
974 		/*
975 		 * Source routing with record.
976 		 * Find interface with current destination address.
977 		 * If none on this machine then drop if strictly routed,
978 		 * or do nothing if loosely routed.
979 		 * Record interface address and bring up next address
980 		 * component.  If strictly routed make sure next
981 		 * address is on directly accessible net.
982 		 */
983 		case IPOPT_LSRR:
984 		case IPOPT_SSRR:
985 			if (ip_allowsrcrt == 0) {
986 				type = ICMP_UNREACH;
987 				code = ICMP_UNREACH_NET_PROHIB;
988 				goto bad;
989 			}
990 			if (optlen < IPOPT_OFFSET + sizeof(*cp)) {
991 				code = &cp[IPOPT_OLEN] - (u_char *)ip;
992 				goto bad;
993 			}
994 			if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
995 				code = &cp[IPOPT_OFFSET] - (u_char *)ip;
996 				goto bad;
997 			}
998 			ipaddr.sin_addr = ip->ip_dst;
999 			ia = ifatoia(ifa_ifwithaddr(sintosa(&ipaddr)));
1000 			if (ia == 0) {
1001 				if (opt == IPOPT_SSRR) {
1002 					type = ICMP_UNREACH;
1003 					code = ICMP_UNREACH_SRCFAIL;
1004 					goto bad;
1005 				}
1006 				/*
1007 				 * Loose routing, and not at next destination
1008 				 * yet; nothing to do except forward.
1009 				 */
1010 				break;
1011 			}
1012 			off--;			/* 0 origin */
1013 			if ((off + sizeof(struct in_addr)) > optlen) {
1014 				/*
1015 				 * End of source route.  Should be for us.
1016 				 */
1017 				save_rte(cp, ip->ip_src);
1018 				break;
1019 			}
1020 			/*
1021 			 * locate outgoing interface
1022 			 */
1023 			memcpy((void *)&ipaddr.sin_addr, (void *)(cp + off),
1024 			    sizeof(ipaddr.sin_addr));
1025 			if (opt == IPOPT_SSRR)
1026 				ia = ifatoia(ifa_ifwithladdr(sintosa(&ipaddr)));
1027 			else
1028 				ia = ip_rtaddr(ipaddr.sin_addr);
1029 			if (ia == 0) {
1030 				type = ICMP_UNREACH;
1031 				code = ICMP_UNREACH_SRCFAIL;
1032 				goto bad;
1033 			}
1034 			ip->ip_dst = ipaddr.sin_addr;
1035 			bcopy((void *)&ia->ia_addr.sin_addr,
1036 			    (void *)(cp + off), sizeof(struct in_addr));
1037 			cp[IPOPT_OFFSET] += sizeof(struct in_addr);
1038 			/*
1039 			 * Let ip_intr's mcast routing check handle mcast pkts
1040 			 */
1041 			forward = !IN_MULTICAST(ip->ip_dst.s_addr);
1042 			break;
1043 
1044 		case IPOPT_RR:
1045 			if (optlen < IPOPT_OFFSET + sizeof(*cp)) {
1046 				code = &cp[IPOPT_OLEN] - (u_char *)ip;
1047 				goto bad;
1048 			}
1049 			if ((off = cp[IPOPT_OFFSET]) < IPOPT_MINOFF) {
1050 				code = &cp[IPOPT_OFFSET] - (u_char *)ip;
1051 				goto bad;
1052 			}
1053 			/*
1054 			 * If no space remains, ignore.
1055 			 */
1056 			off--;			/* 0 origin */
1057 			if ((off + sizeof(struct in_addr)) > optlen)
1058 				break;
1059 			memcpy((void *)&ipaddr.sin_addr, (void *)(&ip->ip_dst),
1060 			    sizeof(ipaddr.sin_addr));
1061 			/*
1062 			 * locate outgoing interface; if we're the destination,
1063 			 * use the incoming interface (should be same).
1064 			 */
1065 			if ((ia = ifatoia(ifa_ifwithaddr(sintosa(&ipaddr))))
1066 			    == NULL &&
1067 			    (ia = ip_rtaddr(ipaddr.sin_addr)) == NULL) {
1068 				type = ICMP_UNREACH;
1069 				code = ICMP_UNREACH_HOST;
1070 				goto bad;
1071 			}
1072 			bcopy((void *)&ia->ia_addr.sin_addr,
1073 			    (void *)(cp + off), sizeof(struct in_addr));
1074 			cp[IPOPT_OFFSET] += sizeof(struct in_addr);
1075 			break;
1076 
1077 		case IPOPT_TS:
1078 			code = cp - (u_char *)ip;
1079 			ipt = (struct ip_timestamp *)cp;
1080 			if (ipt->ipt_len < 4 || ipt->ipt_len > 40) {
1081 				code = (u_char *)&ipt->ipt_len - (u_char *)ip;
1082 				goto bad;
1083 			}
1084 			if (ipt->ipt_ptr < 5) {
1085 				code = (u_char *)&ipt->ipt_ptr - (u_char *)ip;
1086 				goto bad;
1087 			}
1088 			if (ipt->ipt_ptr > ipt->ipt_len - sizeof (int32_t)) {
1089 				if (++ipt->ipt_oflw == 0) {
1090 					code = (u_char *)&ipt->ipt_ptr -
1091 					    (u_char *)ip;
1092 					goto bad;
1093 				}
1094 				break;
1095 			}
1096 			cp0 = (cp + ipt->ipt_ptr - 1);
1097 			switch (ipt->ipt_flg) {
1098 
1099 			case IPOPT_TS_TSONLY:
1100 				break;
1101 
1102 			case IPOPT_TS_TSANDADDR:
1103 				if (ipt->ipt_ptr - 1 + sizeof(n_time) +
1104 				    sizeof(struct in_addr) > ipt->ipt_len) {
1105 					code = (u_char *)&ipt->ipt_ptr -
1106 					    (u_char *)ip;
1107 					goto bad;
1108 				}
1109 				ipaddr.sin_addr = dst;
1110 				ia = ifatoia(ifaof_ifpforaddr(sintosa(&ipaddr),
1111 				    m->m_pkthdr.rcvif));
1112 				if (ia == 0)
1113 					continue;
1114 				bcopy(&ia->ia_addr.sin_addr,
1115 				    cp0, sizeof(struct in_addr));
1116 				ipt->ipt_ptr += sizeof(struct in_addr);
1117 				break;
1118 
1119 			case IPOPT_TS_PRESPEC:
1120 				if (ipt->ipt_ptr - 1 + sizeof(n_time) +
1121 				    sizeof(struct in_addr) > ipt->ipt_len) {
1122 					code = (u_char *)&ipt->ipt_ptr -
1123 					    (u_char *)ip;
1124 					goto bad;
1125 				}
1126 				memcpy(&ipaddr.sin_addr, cp0,
1127 				    sizeof(struct in_addr));
1128 				if (ifatoia(ifa_ifwithaddr(sintosa(&ipaddr)))
1129 				    == NULL)
1130 					continue;
1131 				ipt->ipt_ptr += sizeof(struct in_addr);
1132 				break;
1133 
1134 			default:
1135 				/* XXX can't take &ipt->ipt_flg */
1136 				code = (u_char *)&ipt->ipt_ptr -
1137 				    (u_char *)ip + 1;
1138 				goto bad;
1139 			}
1140 			ntime = iptime();
1141 			cp0 = (u_char *) &ntime; /* XXX grumble, GCC... */
1142 			memmove((char *)cp + ipt->ipt_ptr - 1, cp0,
1143 			    sizeof(n_time));
1144 			ipt->ipt_ptr += sizeof(n_time);
1145 		}
1146 	}
1147 	if (forward) {
1148 		if (ip_forwsrcrt == 0) {
1149 			type = ICMP_UNREACH;
1150 			code = ICMP_UNREACH_SRCFAIL;
1151 			goto bad;
1152 		}
1153 		ip_forward(m, 1);
1154 		return (1);
1155 	}
1156 	return (0);
1157 bad:
1158 	icmp_error(m, type, code, 0, 0);
1159 	IP_STATINC(IP_STAT_BADOPTIONS);
1160 	return (1);
1161 }
1162 
1163 /*
1164  * Given address of next destination (final or next hop),
1165  * return internet address info of interface to be used to get there.
1166  */
1167 struct in_ifaddr *
1168 ip_rtaddr(struct in_addr dst)
1169 {
1170 	struct rtentry *rt;
1171 	union {
1172 		struct sockaddr		dst;
1173 		struct sockaddr_in	dst4;
1174 	} u;
1175 
1176 	sockaddr_in_init(&u.dst4, &dst, 0);
1177 
1178 	if ((rt = rtcache_lookup(&ipforward_rt, &u.dst)) == NULL)
1179 		return NULL;
1180 
1181 	return ifatoia(rt->rt_ifa);
1182 }
1183 
1184 /*
1185  * Save incoming source route for use in replies,
1186  * to be picked up later by ip_srcroute if the receiver is interested.
1187  */
1188 void
1189 save_rte(u_char *option, struct in_addr dst)
1190 {
1191 	unsigned olen;
1192 
1193 	olen = option[IPOPT_OLEN];
1194 #ifdef DIAGNOSTIC
1195 	if (ipprintfs)
1196 		printf("save_rte: olen %d\n", olen);
1197 #endif /* 0 */
1198 	if (olen > sizeof(ip_srcrt) - (1 + sizeof(dst)))
1199 		return;
1200 	memcpy((void *)ip_srcrt.srcopt, (void *)option, olen);
1201 	ip_nhops = (olen - IPOPT_OFFSET - 1) / sizeof(struct in_addr);
1202 	ip_srcrt.dst = dst;
1203 }
1204 
1205 /*
1206  * Retrieve incoming source route for use in replies,
1207  * in the same form used by setsockopt.
1208  * The first hop is placed before the options, will be removed later.
1209  */
1210 struct mbuf *
1211 ip_srcroute(void)
1212 {
1213 	struct in_addr *p, *q;
1214 	struct mbuf *m;
1215 
1216 	if (ip_nhops == 0)
1217 		return NULL;
1218 	m = m_get(M_DONTWAIT, MT_SOOPTS);
1219 	if (m == 0)
1220 		return NULL;
1221 
1222 	MCLAIM(m, &inetdomain.dom_mowner);
1223 #define OPTSIZ	(sizeof(ip_srcrt.nop) + sizeof(ip_srcrt.srcopt))
1224 
1225 	/* length is (nhops+1)*sizeof(addr) + sizeof(nop + srcrt header) */
1226 	m->m_len = ip_nhops * sizeof(struct in_addr) + sizeof(struct in_addr) +
1227 	    OPTSIZ;
1228 #ifdef DIAGNOSTIC
1229 	if (ipprintfs)
1230 		printf("ip_srcroute: nhops %d mlen %d", ip_nhops, m->m_len);
1231 #endif
1232 
1233 	/*
1234 	 * First save first hop for return route
1235 	 */
1236 	p = &ip_srcrt.route[ip_nhops - 1];
1237 	*(mtod(m, struct in_addr *)) = *p--;
1238 #ifdef DIAGNOSTIC
1239 	if (ipprintfs)
1240 		printf(" hops %x", ntohl(mtod(m, struct in_addr *)->s_addr));
1241 #endif
1242 
1243 	/*
1244 	 * Copy option fields and padding (nop) to mbuf.
1245 	 */
1246 	ip_srcrt.nop = IPOPT_NOP;
1247 	ip_srcrt.srcopt[IPOPT_OFFSET] = IPOPT_MINOFF;
1248 	memmove(mtod(m, char *) + sizeof(struct in_addr), &ip_srcrt.nop,
1249 	    OPTSIZ);
1250 	q = (struct in_addr *)(mtod(m, char *) +
1251 	    sizeof(struct in_addr) + OPTSIZ);
1252 #undef OPTSIZ
1253 	/*
1254 	 * Record return path as an IP source route,
1255 	 * reversing the path (pointers are now aligned).
1256 	 */
1257 	while (p >= ip_srcrt.route) {
1258 #ifdef DIAGNOSTIC
1259 		if (ipprintfs)
1260 			printf(" %x", ntohl(q->s_addr));
1261 #endif
1262 		*q++ = *p--;
1263 	}
1264 	/*
1265 	 * Last hop goes to final destination.
1266 	 */
1267 	*q = ip_srcrt.dst;
1268 #ifdef DIAGNOSTIC
1269 	if (ipprintfs)
1270 		printf(" %x\n", ntohl(q->s_addr));
1271 #endif
1272 	return (m);
1273 }
1274 
1275 const int inetctlerrmap[PRC_NCMDS] = {
1276 	[PRC_MSGSIZE] = EMSGSIZE,
1277 	[PRC_HOSTDEAD] = EHOSTDOWN,
1278 	[PRC_HOSTUNREACH] = EHOSTUNREACH,
1279 	[PRC_UNREACH_NET] = EHOSTUNREACH,
1280 	[PRC_UNREACH_HOST] = EHOSTUNREACH,
1281 	[PRC_UNREACH_PROTOCOL] = ECONNREFUSED,
1282 	[PRC_UNREACH_PORT] = ECONNREFUSED,
1283 	[PRC_UNREACH_SRCFAIL] = EHOSTUNREACH,
1284 	[PRC_PARAMPROB] = ENOPROTOOPT,
1285 };
1286 
1287 void
1288 ip_fasttimo(void)
1289 {
1290 	if (ip_drainwanted) {
1291 		ip_drain();
1292 		ip_drainwanted = 0;
1293 	}
1294 }
1295 
1296 void
1297 ip_drainstub(void)
1298 {
1299 	ip_drainwanted = 1;
1300 }
1301 
1302 /*
1303  * Forward a packet.  If some error occurs return the sender
1304  * an icmp packet.  Note we can't always generate a meaningful
1305  * icmp message because icmp doesn't have a large enough repertoire
1306  * of codes and types.
1307  *
1308  * If not forwarding, just drop the packet.  This could be confusing
1309  * if ipforwarding was zero but some routing protocol was advancing
1310  * us as a gateway to somewhere.  However, we must let the routing
1311  * protocol deal with that.
1312  *
1313  * The srcrt parameter indicates whether the packet is being forwarded
1314  * via a source route.
1315  */
1316 void
1317 ip_forward(struct mbuf *m, int srcrt)
1318 {
1319 	struct ip *ip = mtod(m, struct ip *);
1320 	struct rtentry *rt;
1321 	int error, type = 0, code = 0, destmtu = 0;
1322 	struct mbuf *mcopy;
1323 	n_long dest;
1324 	union {
1325 		struct sockaddr		dst;
1326 		struct sockaddr_in	dst4;
1327 	} u;
1328 
1329 	/*
1330 	 * We are now in the output path.
1331 	 */
1332 	MCLAIM(m, &ip_tx_mowner);
1333 
1334 	/*
1335 	 * Clear any in-bound checksum flags for this packet.
1336 	 */
1337 	m->m_pkthdr.csum_flags = 0;
1338 
1339 	dest = 0;
1340 #ifdef DIAGNOSTIC
1341 	if (ipprintfs) {
1342 		printf("forward: src %s ", inet_ntoa(ip->ip_src));
1343 		printf("dst %s ttl %x\n", inet_ntoa(ip->ip_dst), ip->ip_ttl);
1344 	}
1345 #endif
1346 	if (m->m_flags & (M_BCAST|M_MCAST) || in_canforward(ip->ip_dst) == 0) {
1347 		IP_STATINC(IP_STAT_CANTFORWARD);
1348 		m_freem(m);
1349 		return;
1350 	}
1351 	if (ip->ip_ttl <= IPTTLDEC) {
1352 		icmp_error(m, ICMP_TIMXCEED, ICMP_TIMXCEED_INTRANS, dest, 0);
1353 		return;
1354 	}
1355 
1356 	sockaddr_in_init(&u.dst4, &ip->ip_dst, 0);
1357 	if ((rt = rtcache_lookup(&ipforward_rt, &u.dst)) == NULL) {
1358 		icmp_error(m, ICMP_UNREACH, ICMP_UNREACH_NET, dest, 0);
1359 		return;
1360 	}
1361 
1362 	/*
1363 	 * Save at most 68 bytes of the packet in case
1364 	 * we need to generate an ICMP message to the src.
1365 	 * Pullup to avoid sharing mbuf cluster between m and mcopy.
1366 	 */
1367 	mcopy = m_copym(m, 0, imin(ntohs(ip->ip_len), 68), M_DONTWAIT);
1368 	if (mcopy)
1369 		mcopy = m_pullup(mcopy, ip->ip_hl << 2);
1370 
1371 	ip->ip_ttl -= IPTTLDEC;
1372 
1373 	/*
1374 	 * If forwarding packet using same interface that it came in on,
1375 	 * perhaps should send a redirect to sender to shortcut a hop.
1376 	 * Only send redirect if source is sending directly to us,
1377 	 * and if packet was not source routed (or has any options).
1378 	 * Also, don't send redirect if forwarding using a default route
1379 	 * or a route modified by a redirect.
1380 	 */
1381 	if (rt->rt_ifp == m->m_pkthdr.rcvif &&
1382 	    (rt->rt_flags & (RTF_DYNAMIC|RTF_MODIFIED)) == 0 &&
1383 	    !in_nullhost(satocsin(rt_getkey(rt))->sin_addr) &&
1384 	    ipsendredirects && !srcrt) {
1385 		if (rt->rt_ifa &&
1386 		    (ip->ip_src.s_addr & ifatoia(rt->rt_ifa)->ia_subnetmask) ==
1387 		    ifatoia(rt->rt_ifa)->ia_subnet) {
1388 			if (rt->rt_flags & RTF_GATEWAY)
1389 				dest = satosin(rt->rt_gateway)->sin_addr.s_addr;
1390 			else
1391 				dest = ip->ip_dst.s_addr;
1392 			/*
1393 			 * Router requirements says to only send host
1394 			 * redirects.
1395 			 */
1396 			type = ICMP_REDIRECT;
1397 			code = ICMP_REDIRECT_HOST;
1398 #ifdef DIAGNOSTIC
1399 			if (ipprintfs)
1400 				printf("redirect (%d) to %x\n", code,
1401 				    (u_int32_t)dest);
1402 #endif
1403 		}
1404 	}
1405 
1406 	error = ip_output(m, NULL, &ipforward_rt,
1407 	    (IP_FORWARDING | (ip_directedbcast ? IP_ALLOWBROADCAST : 0)),
1408 	    (struct ip_moptions *)NULL, (struct socket *)NULL);
1409 
1410 	if (error)
1411 		IP_STATINC(IP_STAT_CANTFORWARD);
1412 	else {
1413 		uint64_t *ips = IP_STAT_GETREF();
1414 		ips[IP_STAT_FORWARD]++;
1415 		if (type) {
1416 			ips[IP_STAT_REDIRECTSENT]++;
1417 			IP_STAT_PUTREF();
1418 		} else {
1419 			IP_STAT_PUTREF();
1420 			if (mcopy) {
1421 #ifdef GATEWAY
1422 				if (mcopy->m_flags & M_CANFASTFWD)
1423 					ipflow_create(&ipforward_rt, mcopy);
1424 #endif
1425 				m_freem(mcopy);
1426 			}
1427 			return;
1428 		}
1429 	}
1430 	if (mcopy == NULL)
1431 		return;
1432 
1433 	switch (error) {
1434 
1435 	case 0:				/* forwarded, but need redirect */
1436 		/* type, code set above */
1437 		break;
1438 
1439 	case ENETUNREACH:		/* shouldn't happen, checked above */
1440 	case EHOSTUNREACH:
1441 	case ENETDOWN:
1442 	case EHOSTDOWN:
1443 	default:
1444 		type = ICMP_UNREACH;
1445 		code = ICMP_UNREACH_HOST;
1446 		break;
1447 
1448 	case EMSGSIZE:
1449 		type = ICMP_UNREACH;
1450 		code = ICMP_UNREACH_NEEDFRAG;
1451 
1452 		if ((rt = rtcache_validate(&ipforward_rt)) != NULL)
1453 			destmtu = rt->rt_ifp->if_mtu;
1454 
1455 #if defined(IPSEC) || defined(FAST_IPSEC)
1456 		{
1457 			/*
1458 			 * If the packet is routed over IPsec tunnel, tell the
1459 			 * originator the tunnel MTU.
1460 			 *	tunnel MTU = if MTU - sizeof(IP) - ESP/AH hdrsiz
1461 			 * XXX quickhack!!!
1462 			 */
1463 
1464 			struct secpolicy *sp;
1465 			int ipsecerror;
1466 			size_t ipsechdr;
1467 			struct route *ro;
1468 
1469 			sp = ipsec4_getpolicybyaddr(mcopy,
1470 			    IPSEC_DIR_OUTBOUND, IP_FORWARDING,
1471 			    &ipsecerror);
1472 
1473 			if (sp != NULL) {
1474 				/* count IPsec header size */
1475 				ipsechdr = ipsec4_hdrsiz(mcopy,
1476 				    IPSEC_DIR_OUTBOUND, NULL);
1477 
1478 				/*
1479 				 * find the correct route for outer IPv4
1480 				 * header, compute tunnel MTU.
1481 				 */
1482 
1483 				if (sp->req != NULL
1484 				 && sp->req->sav != NULL
1485 				 && sp->req->sav->sah != NULL) {
1486 					ro = &sp->req->sav->sah->sa_route;
1487 					rt = rtcache_validate(ro);
1488 					if (rt && rt->rt_ifp) {
1489 						destmtu =
1490 						    rt->rt_rmx.rmx_mtu ?
1491 						    rt->rt_rmx.rmx_mtu :
1492 						    rt->rt_ifp->if_mtu;
1493 						destmtu -= ipsechdr;
1494 					}
1495 				}
1496 
1497 #ifdef	IPSEC
1498 				key_freesp(sp);
1499 #else
1500 				KEY_FREESP(&sp);
1501 #endif
1502 			}
1503 		}
1504 #endif /*defined(IPSEC) || defined(FAST_IPSEC)*/
1505 		IP_STATINC(IP_STAT_CANTFRAG);
1506 		break;
1507 
1508 	case ENOBUFS:
1509 #if 1
1510 		/*
1511 		 * a router should not generate ICMP_SOURCEQUENCH as
1512 		 * required in RFC1812 Requirements for IP Version 4 Routers.
1513 		 * source quench could be a big problem under DoS attacks,
1514 		 * or if the underlying interface is rate-limited.
1515 		 */
1516 		if (mcopy)
1517 			m_freem(mcopy);
1518 		return;
1519 #else
1520 		type = ICMP_SOURCEQUENCH;
1521 		code = 0;
1522 		break;
1523 #endif
1524 	}
1525 	icmp_error(mcopy, type, code, dest, destmtu);
1526 }
1527 
1528 void
1529 ip_savecontrol(struct inpcb *inp, struct mbuf **mp, struct ip *ip,
1530     struct mbuf *m)
1531 {
1532 
1533 	if (inp->inp_socket->so_options & SO_TIMESTAMP
1534 #ifdef SO_OTIMESTAMP
1535 	    || inp->inp_socket->so_options & SO_OTIMESTAMP
1536 #endif
1537 	    ) {
1538 		struct timeval tv;
1539 
1540 		microtime(&tv);
1541 #ifdef SO_OTIMESTAMP
1542 		if (inp->inp_socket->so_options & SO_OTIMESTAMP) {
1543 			struct timeval50 tv50;
1544 			timeval_to_timeval50(&tv, &tv50);
1545 			*mp = sbcreatecontrol((void *) &tv50, sizeof(tv50),
1546 			    SCM_OTIMESTAMP, SOL_SOCKET);
1547 		} else
1548 #endif
1549 		*mp = sbcreatecontrol((void *) &tv, sizeof(tv),
1550 		    SCM_TIMESTAMP, SOL_SOCKET);
1551 		if (*mp)
1552 			mp = &(*mp)->m_next;
1553 	}
1554 	if (inp->inp_flags & INP_RECVDSTADDR) {
1555 		*mp = sbcreatecontrol((void *) &ip->ip_dst,
1556 		    sizeof(struct in_addr), IP_RECVDSTADDR, IPPROTO_IP);
1557 		if (*mp)
1558 			mp = &(*mp)->m_next;
1559 	}
1560 #ifdef notyet
1561 	/*
1562 	 * XXX
1563 	 * Moving these out of udp_input() made them even more broken
1564 	 * than they already were.
1565 	 *	- fenner@parc.xerox.com
1566 	 */
1567 	/* options were tossed already */
1568 	if (inp->inp_flags & INP_RECVOPTS) {
1569 		*mp = sbcreatecontrol((void *) opts_deleted_above,
1570 		    sizeof(struct in_addr), IP_RECVOPTS, IPPROTO_IP);
1571 		if (*mp)
1572 			mp = &(*mp)->m_next;
1573 	}
1574 	/* ip_srcroute doesn't do what we want here, need to fix */
1575 	if (inp->inp_flags & INP_RECVRETOPTS) {
1576 		*mp = sbcreatecontrol((void *) ip_srcroute(),
1577 		    sizeof(struct in_addr), IP_RECVRETOPTS, IPPROTO_IP);
1578 		if (*mp)
1579 			mp = &(*mp)->m_next;
1580 	}
1581 #endif
1582 	if (inp->inp_flags & INP_RECVIF) {
1583 		struct sockaddr_dl sdl;
1584 
1585 		sockaddr_dl_init(&sdl, sizeof(sdl),
1586 		    (m->m_pkthdr.rcvif != NULL)
1587 		        ?  m->m_pkthdr.rcvif->if_index
1588 			: 0,
1589 			0, NULL, 0, NULL, 0);
1590 		*mp = sbcreatecontrol(&sdl, sdl.sdl_len, IP_RECVIF, IPPROTO_IP);
1591 		if (*mp)
1592 			mp = &(*mp)->m_next;
1593 	}
1594 	if (inp->inp_flags & INP_RECVTTL) {
1595 		*mp = sbcreatecontrol((void *) &ip->ip_ttl,
1596 		    sizeof(uint8_t), IP_RECVTTL, IPPROTO_IP);
1597 		if (*mp)
1598 			mp = &(*mp)->m_next;
1599 	}
1600 }
1601 
1602 /*
1603  * sysctl helper routine for net.inet.ip.forwsrcrt.
1604  */
1605 static int
1606 sysctl_net_inet_ip_forwsrcrt(SYSCTLFN_ARGS)
1607 {
1608 	int error, tmp;
1609 	struct sysctlnode node;
1610 
1611 	node = *rnode;
1612 	tmp = ip_forwsrcrt;
1613 	node.sysctl_data = &tmp;
1614 	error = sysctl_lookup(SYSCTLFN_CALL(&node));
1615 	if (error || newp == NULL)
1616 		return (error);
1617 
1618 	error = kauth_authorize_network(l->l_cred, KAUTH_NETWORK_FORWSRCRT,
1619 	    0, NULL, NULL, NULL);
1620 	if (error)
1621 		return (error);
1622 
1623 	ip_forwsrcrt = tmp;
1624 
1625 	return (0);
1626 }
1627 
1628 /*
1629  * sysctl helper routine for net.inet.ip.mtudisctimeout.  checks the
1630  * range of the new value and tweaks timers if it changes.
1631  */
1632 static int
1633 sysctl_net_inet_ip_pmtudto(SYSCTLFN_ARGS)
1634 {
1635 	int error, tmp;
1636 	struct sysctlnode node;
1637 
1638 	node = *rnode;
1639 	tmp = ip_mtudisc_timeout;
1640 	node.sysctl_data = &tmp;
1641 	error = sysctl_lookup(SYSCTLFN_CALL(&node));
1642 	if (error || newp == NULL)
1643 		return (error);
1644 	if (tmp < 0)
1645 		return (EINVAL);
1646 
1647 	mutex_enter(softnet_lock);
1648 
1649 	ip_mtudisc_timeout = tmp;
1650 	rt_timer_queue_change(ip_mtudisc_timeout_q, ip_mtudisc_timeout);
1651 
1652 	mutex_exit(softnet_lock);
1653 
1654 	return (0);
1655 }
1656 
1657 #ifdef GATEWAY
1658 /*
1659  * sysctl helper routine for net.inet.ip.maxflows.
1660  */
1661 static int
1662 sysctl_net_inet_ip_maxflows(SYSCTLFN_ARGS)
1663 {
1664 	int error;
1665 
1666 	error = sysctl_lookup(SYSCTLFN_CALL(rnode));
1667 	if (error || newp == NULL)
1668 		return (error);
1669 
1670 	mutex_enter(softnet_lock);
1671 	KERNEL_LOCK(1, NULL);
1672 
1673 	ipflow_prune();
1674 
1675 	KERNEL_UNLOCK_ONE(NULL);
1676 	mutex_exit(softnet_lock);
1677 
1678 	return (0);
1679 }
1680 
1681 static int
1682 sysctl_net_inet_ip_hashsize(SYSCTLFN_ARGS)
1683 {
1684 	int error, tmp;
1685 	struct sysctlnode node;
1686 
1687 	node = *rnode;
1688 	tmp = ip_hashsize;
1689 	node.sysctl_data = &tmp;
1690 	error = sysctl_lookup(SYSCTLFN_CALL(&node));
1691 	if (error || newp == NULL)
1692 		return (error);
1693 
1694 	if ((tmp & (tmp - 1)) == 0 && tmp != 0) {
1695 		/*
1696 		 * Can only fail due to malloc()
1697 		 */
1698 		mutex_enter(softnet_lock);
1699 		KERNEL_LOCK(1, NULL);
1700 
1701 		error = ipflow_invalidate_all(tmp);
1702 
1703 		KERNEL_UNLOCK_ONE(NULL);
1704 		mutex_exit(softnet_lock);
1705 
1706 	} else {
1707 		/*
1708 		 * EINVAL if not a power of 2
1709 	         */
1710 		error = EINVAL;
1711 	}
1712 
1713 	return error;
1714 }
1715 #endif /* GATEWAY */
1716 
1717 static int
1718 sysctl_net_inet_ip_stats(SYSCTLFN_ARGS)
1719 {
1720 
1721 	return (NETSTAT_SYSCTL(ipstat_percpu, IP_NSTATS));
1722 }
1723 
1724 static void
1725 sysctl_net_inet_ip_setup(struct sysctllog **clog)
1726 {
1727 	extern int subnetsarelocal, hostzeroisbroadcast;
1728 
1729 	sysctl_createv(clog, 0, NULL, NULL,
1730 		       CTLFLAG_PERMANENT,
1731 		       CTLTYPE_NODE, "net", NULL,
1732 		       NULL, 0, NULL, 0,
1733 		       CTL_NET, CTL_EOL);
1734 	sysctl_createv(clog, 0, NULL, NULL,
1735 		       CTLFLAG_PERMANENT,
1736 		       CTLTYPE_NODE, "inet",
1737 		       SYSCTL_DESCR("PF_INET related settings"),
1738 		       NULL, 0, NULL, 0,
1739 		       CTL_NET, PF_INET, CTL_EOL);
1740 	sysctl_createv(clog, 0, NULL, NULL,
1741 		       CTLFLAG_PERMANENT,
1742 		       CTLTYPE_NODE, "ip",
1743 		       SYSCTL_DESCR("IPv4 related settings"),
1744 		       NULL, 0, NULL, 0,
1745 		       CTL_NET, PF_INET, IPPROTO_IP, CTL_EOL);
1746 
1747 	sysctl_createv(clog, 0, NULL, NULL,
1748 		       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
1749 		       CTLTYPE_INT, "forwarding",
1750 		       SYSCTL_DESCR("Enable forwarding of INET datagrams"),
1751 		       NULL, 0, &ipforwarding, 0,
1752 		       CTL_NET, PF_INET, IPPROTO_IP,
1753 		       IPCTL_FORWARDING, CTL_EOL);
1754 	sysctl_createv(clog, 0, NULL, NULL,
1755 		       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
1756 		       CTLTYPE_INT, "redirect",
1757 		       SYSCTL_DESCR("Enable sending of ICMP redirect messages"),
1758 		       NULL, 0, &ipsendredirects, 0,
1759 		       CTL_NET, PF_INET, IPPROTO_IP,
1760 		       IPCTL_SENDREDIRECTS, CTL_EOL);
1761 	sysctl_createv(clog, 0, NULL, NULL,
1762 		       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
1763 		       CTLTYPE_INT, "ttl",
1764 		       SYSCTL_DESCR("Default TTL for an INET datagram"),
1765 		       NULL, 0, &ip_defttl, 0,
1766 		       CTL_NET, PF_INET, IPPROTO_IP,
1767 		       IPCTL_DEFTTL, CTL_EOL);
1768 #ifdef IPCTL_DEFMTU
1769 	sysctl_createv(clog, 0, NULL, NULL,
1770 		       CTLFLAG_PERMANENT /* |CTLFLAG_READWRITE? */,
1771 		       CTLTYPE_INT, "mtu",
1772 		       SYSCTL_DESCR("Default MTA for an INET route"),
1773 		       NULL, 0, &ip_mtu, 0,
1774 		       CTL_NET, PF_INET, IPPROTO_IP,
1775 		       IPCTL_DEFMTU, CTL_EOL);
1776 #endif /* IPCTL_DEFMTU */
1777 	sysctl_createv(clog, 0, NULL, NULL,
1778 		       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
1779 		       CTLTYPE_INT, "forwsrcrt",
1780 		       SYSCTL_DESCR("Enable forwarding of source-routed "
1781 				    "datagrams"),
1782 		       sysctl_net_inet_ip_forwsrcrt, 0, &ip_forwsrcrt, 0,
1783 		       CTL_NET, PF_INET, IPPROTO_IP,
1784 		       IPCTL_FORWSRCRT, CTL_EOL);
1785 	sysctl_createv(clog, 0, NULL, NULL,
1786 		       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
1787 		       CTLTYPE_INT, "directed-broadcast",
1788 		       SYSCTL_DESCR("Enable forwarding of broadcast datagrams"),
1789 		       NULL, 0, &ip_directedbcast, 0,
1790 		       CTL_NET, PF_INET, IPPROTO_IP,
1791 		       IPCTL_DIRECTEDBCAST, CTL_EOL);
1792 	sysctl_createv(clog, 0, NULL, NULL,
1793 		       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
1794 		       CTLTYPE_INT, "allowsrcrt",
1795 		       SYSCTL_DESCR("Accept source-routed datagrams"),
1796 		       NULL, 0, &ip_allowsrcrt, 0,
1797 		       CTL_NET, PF_INET, IPPROTO_IP,
1798 		       IPCTL_ALLOWSRCRT, CTL_EOL);
1799 	sysctl_createv(clog, 0, NULL, NULL,
1800 		       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
1801 		       CTLTYPE_INT, "subnetsarelocal",
1802 		       SYSCTL_DESCR("Whether logical subnets are considered "
1803 				    "local"),
1804 		       NULL, 0, &subnetsarelocal, 0,
1805 		       CTL_NET, PF_INET, IPPROTO_IP,
1806 		       IPCTL_SUBNETSARELOCAL, CTL_EOL);
1807 	sysctl_createv(clog, 0, NULL, NULL,
1808 		       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
1809 		       CTLTYPE_INT, "mtudisc",
1810 		       SYSCTL_DESCR("Use RFC1191 Path MTU Discovery"),
1811 		       NULL, 0, &ip_mtudisc, 0,
1812 		       CTL_NET, PF_INET, IPPROTO_IP,
1813 		       IPCTL_MTUDISC, CTL_EOL);
1814 	sysctl_createv(clog, 0, NULL, NULL,
1815 		       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
1816 		       CTLTYPE_INT, "anonportmin",
1817 		       SYSCTL_DESCR("Lowest ephemeral port number to assign"),
1818 		       sysctl_net_inet_ip_ports, 0, &anonportmin, 0,
1819 		       CTL_NET, PF_INET, IPPROTO_IP,
1820 		       IPCTL_ANONPORTMIN, CTL_EOL);
1821 	sysctl_createv(clog, 0, NULL, NULL,
1822 		       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
1823 		       CTLTYPE_INT, "anonportmax",
1824 		       SYSCTL_DESCR("Highest ephemeral port number to assign"),
1825 		       sysctl_net_inet_ip_ports, 0, &anonportmax, 0,
1826 		       CTL_NET, PF_INET, IPPROTO_IP,
1827 		       IPCTL_ANONPORTMAX, CTL_EOL);
1828 	sysctl_createv(clog, 0, NULL, NULL,
1829 		       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
1830 		       CTLTYPE_INT, "mtudisctimeout",
1831 		       SYSCTL_DESCR("Lifetime of a Path MTU Discovered route"),
1832 		       sysctl_net_inet_ip_pmtudto, 0, &ip_mtudisc_timeout, 0,
1833 		       CTL_NET, PF_INET, IPPROTO_IP,
1834 		       IPCTL_MTUDISCTIMEOUT, CTL_EOL);
1835 #ifdef GATEWAY
1836 	sysctl_createv(clog, 0, NULL, NULL,
1837 		       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
1838 		       CTLTYPE_INT, "maxflows",
1839 		       SYSCTL_DESCR("Number of flows for fast forwarding"),
1840 		       sysctl_net_inet_ip_maxflows, 0, &ip_maxflows, 0,
1841 		       CTL_NET, PF_INET, IPPROTO_IP,
1842 		       IPCTL_MAXFLOWS, CTL_EOL);
1843 	sysctl_createv(clog, 0, NULL, NULL,
1844 			CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
1845 			CTLTYPE_INT, "hashsize",
1846 			SYSCTL_DESCR("Size of hash table for fast forwarding (IPv4)"),
1847 			sysctl_net_inet_ip_hashsize, 0, &ip_hashsize, 0,
1848 			CTL_NET, PF_INET, IPPROTO_IP,
1849 			CTL_CREATE, CTL_EOL);
1850 #endif /* GATEWAY */
1851 	sysctl_createv(clog, 0, NULL, NULL,
1852 		       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
1853 		       CTLTYPE_INT, "hostzerobroadcast",
1854 		       SYSCTL_DESCR("All zeroes address is broadcast address"),
1855 		       NULL, 0, &hostzeroisbroadcast, 0,
1856 		       CTL_NET, PF_INET, IPPROTO_IP,
1857 		       IPCTL_HOSTZEROBROADCAST, CTL_EOL);
1858 #if NGIF > 0
1859 	sysctl_createv(clog, 0, NULL, NULL,
1860 		       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
1861 		       CTLTYPE_INT, "gifttl",
1862 		       SYSCTL_DESCR("Default TTL for a gif tunnel datagram"),
1863 		       NULL, 0, &ip_gif_ttl, 0,
1864 		       CTL_NET, PF_INET, IPPROTO_IP,
1865 		       IPCTL_GIF_TTL, CTL_EOL);
1866 #endif /* NGIF */
1867 #ifndef IPNOPRIVPORTS
1868 	sysctl_createv(clog, 0, NULL, NULL,
1869 		       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
1870 		       CTLTYPE_INT, "lowportmin",
1871 		       SYSCTL_DESCR("Lowest privileged ephemeral port number "
1872 				    "to assign"),
1873 		       sysctl_net_inet_ip_ports, 0, &lowportmin, 0,
1874 		       CTL_NET, PF_INET, IPPROTO_IP,
1875 		       IPCTL_LOWPORTMIN, CTL_EOL);
1876 	sysctl_createv(clog, 0, NULL, NULL,
1877 		       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
1878 		       CTLTYPE_INT, "lowportmax",
1879 		       SYSCTL_DESCR("Highest privileged ephemeral port number "
1880 				    "to assign"),
1881 		       sysctl_net_inet_ip_ports, 0, &lowportmax, 0,
1882 		       CTL_NET, PF_INET, IPPROTO_IP,
1883 		       IPCTL_LOWPORTMAX, CTL_EOL);
1884 #endif /* IPNOPRIVPORTS */
1885 #if NGRE > 0
1886 	sysctl_createv(clog, 0, NULL, NULL,
1887 		       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
1888 		       CTLTYPE_INT, "grettl",
1889 		       SYSCTL_DESCR("Default TTL for a gre tunnel datagram"),
1890 		       NULL, 0, &ip_gre_ttl, 0,
1891 		       CTL_NET, PF_INET, IPPROTO_IP,
1892 		       IPCTL_GRE_TTL, CTL_EOL);
1893 #endif /* NGRE */
1894 	sysctl_createv(clog, 0, NULL, NULL,
1895 		       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
1896 		       CTLTYPE_INT, "checkinterface",
1897 		       SYSCTL_DESCR("Enable receive side of Strong ES model "
1898 				    "from RFC1122"),
1899 		       NULL, 0, &ip_checkinterface, 0,
1900 		       CTL_NET, PF_INET, IPPROTO_IP,
1901 		       IPCTL_CHECKINTERFACE, CTL_EOL);
1902 	sysctl_createv(clog, 0, NULL, NULL,
1903 		       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
1904 		       CTLTYPE_INT, "random_id",
1905 		       SYSCTL_DESCR("Assign random ip_id values"),
1906 		       NULL, 0, &ip_do_randomid, 0,
1907 		       CTL_NET, PF_INET, IPPROTO_IP,
1908 		       IPCTL_RANDOMID, CTL_EOL);
1909 	sysctl_createv(clog, 0, NULL, NULL,
1910 		       CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
1911 		       CTLTYPE_INT, "do_loopback_cksum",
1912 		       SYSCTL_DESCR("Perform IP checksum on loopback"),
1913 		       NULL, 0, &ip_do_loopback_cksum, 0,
1914 		       CTL_NET, PF_INET, IPPROTO_IP,
1915 		       IPCTL_LOOPBACKCKSUM, CTL_EOL);
1916 	sysctl_createv(clog, 0, NULL, NULL,
1917 		       CTLFLAG_PERMANENT,
1918 		       CTLTYPE_STRUCT, "stats",
1919 		       SYSCTL_DESCR("IP statistics"),
1920 		       sysctl_net_inet_ip_stats, 0, NULL, 0,
1921 		       CTL_NET, PF_INET, IPPROTO_IP, IPCTL_STATS,
1922 		       CTL_EOL);
1923 }
1924 
1925 void
1926 ip_statinc(u_int stat)
1927 {
1928 
1929 	KASSERT(stat < IP_NSTATS);
1930 	IP_STATINC(stat);
1931 }
1932