xref: /freebsd/sys/netinet6/ip6_input.c (revision ca987d4641cdcd7f27e153db17c5bf064934faf5)
1 /*-
2  * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  * 3. Neither the name of the project nor the names of its contributors
14  *    may be used to endorse or promote products derived from this software
15  *    without specific prior written permission.
16  *
17  * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27  * SUCH DAMAGE.
28  *
29  *	$KAME: ip6_input.c,v 1.259 2002/01/21 04:58:09 jinmei Exp $
30  */
31 
32 /*-
33  * Copyright (c) 1982, 1986, 1988, 1993
34  *	The Regents of the University of California.  All rights reserved.
35  *
36  * Redistribution and use in source and binary forms, with or without
37  * modification, are permitted provided that the following conditions
38  * are met:
39  * 1. Redistributions of source code must retain the above copyright
40  *    notice, this list of conditions and the following disclaimer.
41  * 2. Redistributions in binary form must reproduce the above copyright
42  *    notice, this list of conditions and the following disclaimer in the
43  *    documentation and/or other materials provided with the distribution.
44  * 3. Neither the name of the University nor the names of its contributors
45  *    may be used to endorse or promote products derived from this software
46  *    without specific prior written permission.
47  *
48  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
49  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
50  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
51  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
52  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
53  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
54  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
55  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
56  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
57  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
58  * SUCH DAMAGE.
59  *
60  *	@(#)ip_input.c	8.2 (Berkeley) 1/4/94
61  */
62 
63 #include <sys/cdefs.h>
64 __FBSDID("$FreeBSD$");
65 
66 #include "opt_inet.h"
67 #include "opt_inet6.h"
68 #include "opt_ipsec.h"
69 #include "opt_route.h"
70 #include "opt_rss.h"
71 
72 #include <sys/param.h>
73 #include <sys/systm.h>
74 #include <sys/hhook.h>
75 #include <sys/malloc.h>
76 #include <sys/mbuf.h>
77 #include <sys/proc.h>
78 #include <sys/domain.h>
79 #include <sys/protosw.h>
80 #include <sys/sdt.h>
81 #include <sys/socket.h>
82 #include <sys/socketvar.h>
83 #include <sys/errno.h>
84 #include <sys/time.h>
85 #include <sys/kernel.h>
86 #include <sys/lock.h>
87 #include <sys/rmlock.h>
88 #include <sys/syslog.h>
89 #include <sys/sysctl.h>
90 
91 #include <net/if.h>
92 #include <net/if_var.h>
93 #include <net/if_types.h>
94 #include <net/if_dl.h>
95 #include <net/route.h>
96 #include <net/netisr.h>
97 #include <net/rss_config.h>
98 #include <net/pfil.h>
99 #include <net/vnet.h>
100 
101 #include <netinet/in.h>
102 #include <netinet/in_kdtrace.h>
103 #include <netinet/ip_var.h>
104 #include <netinet/in_systm.h>
105 #include <net/if_llatbl.h>
106 #ifdef INET
107 #include <netinet/ip.h>
108 #include <netinet/ip_icmp.h>
109 #endif /* INET */
110 #include <netinet/ip6.h>
111 #include <netinet6/in6_var.h>
112 #include <netinet6/ip6_var.h>
113 #include <netinet/in_pcb.h>
114 #include <netinet/icmp6.h>
115 #include <netinet6/scope6_var.h>
116 #include <netinet6/in6_ifattach.h>
117 #include <netinet6/mld6_var.h>
118 #include <netinet6/nd6.h>
119 #include <netinet6/in6_rss.h>
120 
121 #include <netipsec/ipsec_support.h>
122 
123 #include <netinet6/ip6protosw.h>
124 
125 extern struct domain inet6domain;
126 
127 u_char ip6_protox[IPPROTO_MAX];
128 VNET_DEFINE(struct in6_ifaddrhead, in6_ifaddrhead);
129 VNET_DEFINE(struct in6_ifaddrlisthead *, in6_ifaddrhashtbl);
130 VNET_DEFINE(u_long, in6_ifaddrhmask);
131 
132 static struct netisr_handler ip6_nh = {
133 	.nh_name = "ip6",
134 	.nh_handler = ip6_input,
135 	.nh_proto = NETISR_IPV6,
136 #ifdef RSS
137 	.nh_m2cpuid = rss_soft_m2cpuid_v6,
138 	.nh_policy = NETISR_POLICY_CPU,
139 	.nh_dispatch = NETISR_DISPATCH_HYBRID,
140 #else
141 	.nh_policy = NETISR_POLICY_FLOW,
142 #endif
143 };
144 
145 static int
146 sysctl_netinet6_intr_queue_maxlen(SYSCTL_HANDLER_ARGS)
147 {
148 	int error, qlimit;
149 
150 	netisr_getqlimit(&ip6_nh, &qlimit);
151 	error = sysctl_handle_int(oidp, &qlimit, 0, req);
152 	if (error || !req->newptr)
153 		return (error);
154 	if (qlimit < 1)
155 		return (EINVAL);
156 	return (netisr_setqlimit(&ip6_nh, qlimit));
157 }
158 SYSCTL_DECL(_net_inet6_ip6);
159 SYSCTL_PROC(_net_inet6_ip6, IPV6CTL_INTRQMAXLEN, intr_queue_maxlen,
160     CTLTYPE_INT|CTLFLAG_RW, 0, 0, sysctl_netinet6_intr_queue_maxlen, "I",
161     "Maximum size of the IPv6 input queue");
162 
163 #ifdef RSS
164 static struct netisr_handler ip6_direct_nh = {
165 	.nh_name = "ip6_direct",
166 	.nh_handler = ip6_direct_input,
167 	.nh_proto = NETISR_IPV6_DIRECT,
168 	.nh_m2cpuid = rss_soft_m2cpuid_v6,
169 	.nh_policy = NETISR_POLICY_CPU,
170 	.nh_dispatch = NETISR_DISPATCH_HYBRID,
171 };
172 
173 static int
174 sysctl_netinet6_intr_direct_queue_maxlen(SYSCTL_HANDLER_ARGS)
175 {
176 	int error, qlimit;
177 
178 	netisr_getqlimit(&ip6_direct_nh, &qlimit);
179 	error = sysctl_handle_int(oidp, &qlimit, 0, req);
180 	if (error || !req->newptr)
181 		return (error);
182 	if (qlimit < 1)
183 		return (EINVAL);
184 	return (netisr_setqlimit(&ip6_direct_nh, qlimit));
185 }
186 SYSCTL_PROC(_net_inet6_ip6, IPV6CTL_INTRDQMAXLEN, intr_direct_queue_maxlen,
187     CTLTYPE_INT|CTLFLAG_RW, 0, 0, sysctl_netinet6_intr_direct_queue_maxlen,
188     "I", "Maximum size of the IPv6 direct input queue");
189 
190 #endif
191 
192 VNET_DEFINE(struct pfil_head, inet6_pfil_hook);
193 
194 VNET_PCPUSTAT_DEFINE(struct ip6stat, ip6stat);
195 VNET_PCPUSTAT_SYSINIT(ip6stat);
196 #ifdef VIMAGE
197 VNET_PCPUSTAT_SYSUNINIT(ip6stat);
198 #endif /* VIMAGE */
199 
200 struct rmlock in6_ifaddr_lock;
201 RM_SYSINIT(in6_ifaddr_lock, &in6_ifaddr_lock, "in6_ifaddr_lock");
202 
203 static int ip6_hopopts_input(u_int32_t *, u_int32_t *, struct mbuf **, int *);
204 #ifdef PULLDOWN_TEST
205 static struct mbuf *ip6_pullexthdr(struct mbuf *, size_t, int);
206 #endif
207 
208 /*
209  * IP6 initialization: fill in IP6 protocol switch table.
210  * All protocols not implemented in kernel go to raw IP6 protocol handler.
211  */
212 void
213 ip6_init(void)
214 {
215 	struct protosw *pr;
216 	int i;
217 
218 	TUNABLE_INT_FETCH("net.inet6.ip6.auto_linklocal",
219 	    &V_ip6_auto_linklocal);
220 	TUNABLE_INT_FETCH("net.inet6.ip6.accept_rtadv", &V_ip6_accept_rtadv);
221 	TUNABLE_INT_FETCH("net.inet6.ip6.no_radr", &V_ip6_no_radr);
222 
223 	TAILQ_INIT(&V_in6_ifaddrhead);
224 	V_in6_ifaddrhashtbl = hashinit(IN6ADDR_NHASH, M_IFADDR,
225 	    &V_in6_ifaddrhmask);
226 
227 	/* Initialize packet filter hooks. */
228 	V_inet6_pfil_hook.ph_type = PFIL_TYPE_AF;
229 	V_inet6_pfil_hook.ph_af = AF_INET6;
230 	if ((i = pfil_head_register(&V_inet6_pfil_hook)) != 0)
231 		printf("%s: WARNING: unable to register pfil hook, "
232 			"error %d\n", __func__, i);
233 
234 	if (hhook_head_register(HHOOK_TYPE_IPSEC_IN, AF_INET6,
235 	    &V_ipsec_hhh_in[HHOOK_IPSEC_INET6],
236 	    HHOOK_WAITOK | HHOOK_HEADISINVNET) != 0)
237 		printf("%s: WARNING: unable to register input helper hook\n",
238 		    __func__);
239 	if (hhook_head_register(HHOOK_TYPE_IPSEC_OUT, AF_INET6,
240 	    &V_ipsec_hhh_out[HHOOK_IPSEC_INET6],
241 	    HHOOK_WAITOK | HHOOK_HEADISINVNET) != 0)
242 		printf("%s: WARNING: unable to register output helper hook\n",
243 		    __func__);
244 
245 	scope6_init();
246 	addrsel_policy_init();
247 	nd6_init();
248 	frag6_init();
249 
250 	V_ip6_desync_factor = arc4random() % MAX_TEMP_DESYNC_FACTOR;
251 
252 	/* Skip global initialization stuff for non-default instances. */
253 #ifdef VIMAGE
254 	if (!IS_DEFAULT_VNET(curvnet)) {
255 		netisr_register_vnet(&ip6_nh);
256 #ifdef RSS
257 		netisr_register_vnet(&ip6_direct_nh);
258 #endif
259 		return;
260 	}
261 #endif
262 
263 	pr = pffindproto(PF_INET6, IPPROTO_RAW, SOCK_RAW);
264 	if (pr == NULL)
265 		panic("ip6_init");
266 
267 	/* Initialize the entire ip6_protox[] array to IPPROTO_RAW. */
268 	for (i = 0; i < IPPROTO_MAX; i++)
269 		ip6_protox[i] = pr - inet6sw;
270 	/*
271 	 * Cycle through IP protocols and put them into the appropriate place
272 	 * in ip6_protox[].
273 	 */
274 	for (pr = inet6domain.dom_protosw;
275 	    pr < inet6domain.dom_protoswNPROTOSW; pr++)
276 		if (pr->pr_domain->dom_family == PF_INET6 &&
277 		    pr->pr_protocol && pr->pr_protocol != IPPROTO_RAW) {
278 			/* Be careful to only index valid IP protocols. */
279 			if (pr->pr_protocol < IPPROTO_MAX)
280 				ip6_protox[pr->pr_protocol] = pr - inet6sw;
281 		}
282 
283 	netisr_register(&ip6_nh);
284 #ifdef RSS
285 	netisr_register(&ip6_direct_nh);
286 #endif
287 }
288 
289 /*
290  * The protocol to be inserted into ip6_protox[] must be already registered
291  * in inet6sw[], either statically or through pf_proto_register().
292  */
293 int
294 ip6proto_register(short ip6proto)
295 {
296 	struct protosw *pr;
297 
298 	/* Sanity checks. */
299 	if (ip6proto <= 0 || ip6proto >= IPPROTO_MAX)
300 		return (EPROTONOSUPPORT);
301 
302 	/*
303 	 * The protocol slot must not be occupied by another protocol
304 	 * already.  An index pointing to IPPROTO_RAW is unused.
305 	 */
306 	pr = pffindproto(PF_INET6, IPPROTO_RAW, SOCK_RAW);
307 	if (pr == NULL)
308 		return (EPFNOSUPPORT);
309 	if (ip6_protox[ip6proto] != pr - inet6sw)	/* IPPROTO_RAW */
310 		return (EEXIST);
311 
312 	/*
313 	 * Find the protocol position in inet6sw[] and set the index.
314 	 */
315 	for (pr = inet6domain.dom_protosw;
316 	    pr < inet6domain.dom_protoswNPROTOSW; pr++) {
317 		if (pr->pr_domain->dom_family == PF_INET6 &&
318 		    pr->pr_protocol && pr->pr_protocol == ip6proto) {
319 			ip6_protox[pr->pr_protocol] = pr - inet6sw;
320 			return (0);
321 		}
322 	}
323 	return (EPROTONOSUPPORT);
324 }
325 
326 int
327 ip6proto_unregister(short ip6proto)
328 {
329 	struct protosw *pr;
330 
331 	/* Sanity checks. */
332 	if (ip6proto <= 0 || ip6proto >= IPPROTO_MAX)
333 		return (EPROTONOSUPPORT);
334 
335 	/* Check if the protocol was indeed registered. */
336 	pr = pffindproto(PF_INET6, IPPROTO_RAW, SOCK_RAW);
337 	if (pr == NULL)
338 		return (EPFNOSUPPORT);
339 	if (ip6_protox[ip6proto] == pr - inet6sw)	/* IPPROTO_RAW */
340 		return (ENOENT);
341 
342 	/* Reset the protocol slot to IPPROTO_RAW. */
343 	ip6_protox[ip6proto] = pr - inet6sw;
344 	return (0);
345 }
346 
347 #ifdef VIMAGE
348 static void
349 ip6_destroy(void *unused __unused)
350 {
351 	struct ifaddr *ifa, *nifa;
352 	struct ifnet *ifp;
353 	int error;
354 
355 #ifdef RSS
356 	netisr_unregister_vnet(&ip6_direct_nh);
357 #endif
358 	netisr_unregister_vnet(&ip6_nh);
359 
360 	if ((error = pfil_head_unregister(&V_inet6_pfil_hook)) != 0)
361 		printf("%s: WARNING: unable to unregister pfil hook, "
362 		    "error %d\n", __func__, error);
363 	error = hhook_head_deregister(V_ipsec_hhh_in[HHOOK_IPSEC_INET6]);
364 	if (error != 0) {
365 		printf("%s: WARNING: unable to deregister input helper hook "
366 		    "type HHOOK_TYPE_IPSEC_IN, id HHOOK_IPSEC_INET6: "
367 		    "error %d returned\n", __func__, error);
368 	}
369 	error = hhook_head_deregister(V_ipsec_hhh_out[HHOOK_IPSEC_INET6]);
370 	if (error != 0) {
371 		printf("%s: WARNING: unable to deregister output helper hook "
372 		    "type HHOOK_TYPE_IPSEC_OUT, id HHOOK_IPSEC_INET6: "
373 		    "error %d returned\n", __func__, error);
374 	}
375 
376 	/* Cleanup addresses. */
377 	IFNET_RLOCK();
378 	TAILQ_FOREACH(ifp, &V_ifnet, if_link) {
379 		/* Cannot lock here - lock recursion. */
380 		/* IF_ADDR_LOCK(ifp); */
381 		TAILQ_FOREACH_SAFE(ifa, &ifp->if_addrhead, ifa_link, nifa) {
382 
383 			if (ifa->ifa_addr->sa_family != AF_INET6)
384 				continue;
385 			in6_purgeaddr(ifa);
386 		}
387 		/* IF_ADDR_UNLOCK(ifp); */
388 		in6_ifdetach_destroy(ifp);
389 		mld_domifdetach(ifp);
390 		/* Make sure any routes are gone as well. */
391 		rt_flushifroutes_af(ifp, AF_INET6);
392 	}
393 	IFNET_RUNLOCK();
394 
395 	nd6_destroy();
396 	in6_ifattach_destroy();
397 
398 	hashdestroy(V_in6_ifaddrhashtbl, M_IFADDR, V_in6_ifaddrhmask);
399 }
400 
401 VNET_SYSUNINIT(inet6, SI_SUB_PROTO_DOMAIN, SI_ORDER_THIRD, ip6_destroy, NULL);
402 #endif
403 
404 static int
405 ip6_input_hbh(struct mbuf *m, uint32_t *plen, uint32_t *rtalert, int *off,
406     int *nxt, int *ours)
407 {
408 	struct ip6_hdr *ip6;
409 	struct ip6_hbh *hbh;
410 
411 	if (ip6_hopopts_input(plen, rtalert, &m, off)) {
412 #if 0	/*touches NULL pointer*/
413 		in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_discard);
414 #endif
415 		goto out;	/* m have already been freed */
416 	}
417 
418 	/* adjust pointer */
419 	ip6 = mtod(m, struct ip6_hdr *);
420 
421 	/*
422 	 * if the payload length field is 0 and the next header field
423 	 * indicates Hop-by-Hop Options header, then a Jumbo Payload
424 	 * option MUST be included.
425 	 */
426 	if (ip6->ip6_plen == 0 && *plen == 0) {
427 		/*
428 		 * Note that if a valid jumbo payload option is
429 		 * contained, ip6_hopopts_input() must set a valid
430 		 * (non-zero) payload length to the variable plen.
431 		 */
432 		IP6STAT_INC(ip6s_badoptions);
433 		in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_discard);
434 		in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_hdrerr);
435 		icmp6_error(m, ICMP6_PARAM_PROB,
436 			    ICMP6_PARAMPROB_HEADER,
437 			    (caddr_t)&ip6->ip6_plen - (caddr_t)ip6);
438 		goto out;
439 	}
440 #ifndef PULLDOWN_TEST
441 	/* ip6_hopopts_input() ensures that mbuf is contiguous */
442 	hbh = (struct ip6_hbh *)(ip6 + 1);
443 #else
444 	IP6_EXTHDR_GET(hbh, struct ip6_hbh *, m, sizeof(struct ip6_hdr),
445 		sizeof(struct ip6_hbh));
446 	if (hbh == NULL) {
447 		IP6STAT_INC(ip6s_tooshort);
448 		goto out;
449 	}
450 #endif
451 	*nxt = hbh->ip6h_nxt;
452 
453 	/*
454 	 * If we are acting as a router and the packet contains a
455 	 * router alert option, see if we know the option value.
456 	 * Currently, we only support the option value for MLD, in which
457 	 * case we should pass the packet to the multicast routing
458 	 * daemon.
459 	 */
460 	if (*rtalert != ~0) {
461 		switch (*rtalert) {
462 		case IP6OPT_RTALERT_MLD:
463 			if (V_ip6_forwarding)
464 				*ours = 1;
465 			break;
466 		default:
467 			/*
468 			 * RFC2711 requires unrecognized values must be
469 			 * silently ignored.
470 			 */
471 			break;
472 		}
473 	}
474 
475 	return (0);
476 
477 out:
478 	return (1);
479 }
480 
481 #ifdef RSS
482 /*
483  * IPv6 direct input routine.
484  *
485  * This is called when reinjecting completed fragments where
486  * all of the previous checking and book-keeping has been done.
487  */
488 void
489 ip6_direct_input(struct mbuf *m)
490 {
491 	int off, nxt;
492 	int nest;
493 	struct m_tag *mtag;
494 	struct ip6_direct_ctx *ip6dc;
495 
496 	mtag = m_tag_locate(m, MTAG_ABI_IPV6, IPV6_TAG_DIRECT, NULL);
497 	KASSERT(mtag != NULL, ("Reinjected packet w/o direct ctx tag!"));
498 
499 	ip6dc = (struct ip6_direct_ctx *)(mtag + 1);
500 	nxt = ip6dc->ip6dc_nxt;
501 	off = ip6dc->ip6dc_off;
502 
503 	nest = 0;
504 
505 	m_tag_delete(m, mtag);
506 
507 	while (nxt != IPPROTO_DONE) {
508 		if (V_ip6_hdrnestlimit && (++nest > V_ip6_hdrnestlimit)) {
509 			IP6STAT_INC(ip6s_toomanyhdr);
510 			goto bad;
511 		}
512 
513 		/*
514 		 * protection against faulty packet - there should be
515 		 * more sanity checks in header chain processing.
516 		 */
517 		if (m->m_pkthdr.len < off) {
518 			IP6STAT_INC(ip6s_tooshort);
519 			in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_truncated);
520 			goto bad;
521 		}
522 
523 #if defined(IPSEC) || defined(IPSEC_SUPPORT)
524 		if (IPSEC_ENABLED(ipv6)) {
525 			if (IPSEC_INPUT(ipv6, m, off, nxt) != 0)
526 				return;
527 		}
528 #endif /* IPSEC */
529 
530 		nxt = (*inet6sw[ip6_protox[nxt]].pr_input)(&m, &off, nxt);
531 	}
532 	return;
533 bad:
534 	m_freem(m);
535 }
536 #endif
537 
538 void
539 ip6_input(struct mbuf *m)
540 {
541 	struct in6_addr odst;
542 	struct ip6_hdr *ip6;
543 	struct in6_ifaddr *ia;
544 	struct ifnet *rcvif;
545 	u_int32_t plen;
546 	u_int32_t rtalert = ~0;
547 	int off = sizeof(struct ip6_hdr), nest;
548 	int nxt, ours = 0;
549 	int srcrt = 0;
550 
551 	/*
552 	 * Drop the packet if IPv6 operation is disabled on the interface.
553 	 */
554 	rcvif = m->m_pkthdr.rcvif;
555 	if ((ND_IFINFO(rcvif)->flags & ND6_IFF_IFDISABLED))
556 		goto bad;
557 
558 #if defined(IPSEC) || defined(IPSEC_SUPPORT)
559 	/*
560 	 * should the inner packet be considered authentic?
561 	 * see comment in ah4_input().
562 	 * NB: m cannot be NULL when passed to the input routine
563 	 */
564 
565 	m->m_flags &= ~M_AUTHIPHDR;
566 	m->m_flags &= ~M_AUTHIPDGM;
567 
568 #endif /* IPSEC */
569 
570 	if (m->m_flags & M_FASTFWD_OURS) {
571 		/*
572 		 * Firewall changed destination to local.
573 		 */
574 		m->m_flags &= ~M_FASTFWD_OURS;
575 		ours = 1;
576 		ip6 = mtod(m, struct ip6_hdr *);
577 		goto hbhcheck;
578 	}
579 
580 	/*
581 	 * mbuf statistics
582 	 */
583 	if (m->m_flags & M_EXT) {
584 		if (m->m_next)
585 			IP6STAT_INC(ip6s_mext2m);
586 		else
587 			IP6STAT_INC(ip6s_mext1);
588 	} else {
589 		if (m->m_next) {
590 			if (m->m_flags & M_LOOP) {
591 				IP6STAT_INC(ip6s_m2m[V_loif->if_index]);
592 			} else if (rcvif->if_index < IP6S_M2MMAX)
593 				IP6STAT_INC(ip6s_m2m[rcvif->if_index]);
594 			else
595 				IP6STAT_INC(ip6s_m2m[0]);
596 		} else
597 			IP6STAT_INC(ip6s_m1);
598 	}
599 
600 	in6_ifstat_inc(rcvif, ifs6_in_receive);
601 	IP6STAT_INC(ip6s_total);
602 
603 #ifndef PULLDOWN_TEST
604 	/*
605 	 * L2 bridge code and some other code can return mbuf chain
606 	 * that does not conform to KAME requirement.  too bad.
607 	 * XXX: fails to join if interface MTU > MCLBYTES.  jumbogram?
608 	 */
609 	if (m && m->m_next != NULL && m->m_pkthdr.len < MCLBYTES) {
610 		struct mbuf *n;
611 
612 		if (m->m_pkthdr.len > MHLEN)
613 			n = m_getcl(M_NOWAIT, MT_DATA, M_PKTHDR);
614 		else
615 			n = m_gethdr(M_NOWAIT, MT_DATA);
616 		if (n == NULL)
617 			goto bad;
618 
619 		m_move_pkthdr(n, m);
620 		m_copydata(m, 0, n->m_pkthdr.len, mtod(n, caddr_t));
621 		n->m_len = n->m_pkthdr.len;
622 		m_freem(m);
623 		m = n;
624 	}
625 	IP6_EXTHDR_CHECK(m, 0, sizeof(struct ip6_hdr), /* nothing */);
626 #endif
627 
628 	if (m->m_len < sizeof(struct ip6_hdr)) {
629 		if ((m = m_pullup(m, sizeof(struct ip6_hdr))) == NULL) {
630 			IP6STAT_INC(ip6s_toosmall);
631 			in6_ifstat_inc(rcvif, ifs6_in_hdrerr);
632 			goto bad;
633 		}
634 	}
635 
636 	ip6 = mtod(m, struct ip6_hdr *);
637 	if ((ip6->ip6_vfc & IPV6_VERSION_MASK) != IPV6_VERSION) {
638 		IP6STAT_INC(ip6s_badvers);
639 		in6_ifstat_inc(rcvif, ifs6_in_hdrerr);
640 		goto bad;
641 	}
642 
643 	IP6STAT_INC(ip6s_nxthist[ip6->ip6_nxt]);
644 	IP_PROBE(receive, NULL, NULL, ip6, rcvif, NULL, ip6);
645 
646 	/*
647 	 * Check against address spoofing/corruption.
648 	 */
649 	if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_src) ||
650 	    IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_dst)) {
651 		/*
652 		 * XXX: "badscope" is not very suitable for a multicast source.
653 		 */
654 		IP6STAT_INC(ip6s_badscope);
655 		in6_ifstat_inc(rcvif, ifs6_in_addrerr);
656 		goto bad;
657 	}
658 	if (IN6_IS_ADDR_MC_INTFACELOCAL(&ip6->ip6_dst) &&
659 	    !(m->m_flags & M_LOOP)) {
660 		/*
661 		 * In this case, the packet should come from the loopback
662 		 * interface.  However, we cannot just check the if_flags,
663 		 * because ip6_mloopback() passes the "actual" interface
664 		 * as the outgoing/incoming interface.
665 		 */
666 		IP6STAT_INC(ip6s_badscope);
667 		in6_ifstat_inc(rcvif, ifs6_in_addrerr);
668 		goto bad;
669 	}
670 	if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) &&
671 	    IPV6_ADDR_MC_SCOPE(&ip6->ip6_dst) == 0) {
672 		/*
673 		 * RFC4291 2.7:
674 		 * Nodes must not originate a packet to a multicast address
675 		 * whose scop field contains the reserved value 0; if such
676 		 * a packet is received, it must be silently dropped.
677 		 */
678 		IP6STAT_INC(ip6s_badscope);
679 		in6_ifstat_inc(rcvif, ifs6_in_addrerr);
680 		goto bad;
681 	}
682 #ifdef ALTQ
683 	if (altq_input != NULL && (*altq_input)(m, AF_INET6) == 0) {
684 		/* packet is dropped by traffic conditioner */
685 		return;
686 	}
687 #endif
688 	/*
689 	 * The following check is not documented in specs.  A malicious
690 	 * party may be able to use IPv4 mapped addr to confuse tcp/udp stack
691 	 * and bypass security checks (act as if it was from 127.0.0.1 by using
692 	 * IPv6 src ::ffff:127.0.0.1).  Be cautious.
693 	 *
694 	 * This check chokes if we are in an SIIT cloud.  As none of BSDs
695 	 * support IPv4-less kernel compilation, we cannot support SIIT
696 	 * environment at all.  So, it makes more sense for us to reject any
697 	 * malicious packets for non-SIIT environment, than try to do a
698 	 * partial support for SIIT environment.
699 	 */
700 	if (IN6_IS_ADDR_V4MAPPED(&ip6->ip6_src) ||
701 	    IN6_IS_ADDR_V4MAPPED(&ip6->ip6_dst)) {
702 		IP6STAT_INC(ip6s_badscope);
703 		in6_ifstat_inc(rcvif, ifs6_in_addrerr);
704 		goto bad;
705 	}
706 #if 0
707 	/*
708 	 * Reject packets with IPv4 compatible addresses (auto tunnel).
709 	 *
710 	 * The code forbids auto tunnel relay case in RFC1933 (the check is
711 	 * stronger than RFC1933).  We may want to re-enable it if mech-xx
712 	 * is revised to forbid relaying case.
713 	 */
714 	if (IN6_IS_ADDR_V4COMPAT(&ip6->ip6_src) ||
715 	    IN6_IS_ADDR_V4COMPAT(&ip6->ip6_dst)) {
716 		IP6STAT_INC(ip6s_badscope);
717 		in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_addrerr);
718 		goto bad;
719 	}
720 #endif
721 	/*
722 	 * Try to forward the packet, but if we fail continue.
723 	 * ip6_tryforward() does inbound and outbound packet firewall
724 	 * processing. If firewall has decided that destination becomes
725 	 * our local address, it sets M_FASTFWD_OURS flag. In this
726 	 * case skip another inbound firewall processing and update
727 	 * ip6 pointer.
728 	 */
729 	if (V_ip6_forwarding != 0
730 #if defined(IPSEC) || defined(IPSEC_SUPPORT)
731 	    && (!IPSEC_ENABLED(ipv6) ||
732 	    IPSEC_CAPS(ipv6, m, IPSEC_CAP_OPERABLE) == 0)
733 #endif
734 	    ) {
735 		if ((m = ip6_tryforward(m)) == NULL)
736 			return;
737 		if (m->m_flags & M_FASTFWD_OURS) {
738 			m->m_flags &= ~M_FASTFWD_OURS;
739 			ours = 1;
740 			ip6 = mtod(m, struct ip6_hdr *);
741 			goto hbhcheck;
742 		}
743 	}
744 #if defined(IPSEC) || defined(IPSEC_SUPPORT)
745 	/*
746 	 * Bypass packet filtering for packets previously handled by IPsec.
747 	 */
748 	if (IPSEC_ENABLED(ipv6) &&
749 	    IPSEC_CAPS(ipv6, m, IPSEC_CAP_BYPASS_FILTER) != 0)
750 			goto passin;
751 #endif
752 	/*
753 	 * Run through list of hooks for input packets.
754 	 *
755 	 * NB: Beware of the destination address changing
756 	 *     (e.g. by NAT rewriting).  When this happens,
757 	 *     tell ip6_forward to do the right thing.
758 	 */
759 
760 	/* Jump over all PFIL processing if hooks are not active. */
761 	if (!PFIL_HOOKED(&V_inet6_pfil_hook))
762 		goto passin;
763 
764 	odst = ip6->ip6_dst;
765 	if (pfil_run_hooks(&V_inet6_pfil_hook, &m,
766 	    m->m_pkthdr.rcvif, PFIL_IN, NULL))
767 		return;
768 	if (m == NULL)			/* consumed by filter */
769 		return;
770 	ip6 = mtod(m, struct ip6_hdr *);
771 	srcrt = !IN6_ARE_ADDR_EQUAL(&odst, &ip6->ip6_dst);
772 
773 	if (m->m_flags & M_FASTFWD_OURS) {
774 		m->m_flags &= ~M_FASTFWD_OURS;
775 		ours = 1;
776 		goto hbhcheck;
777 	}
778 	if ((m->m_flags & M_IP6_NEXTHOP) &&
779 	    m_tag_find(m, PACKET_TAG_IPFORWARD, NULL) != NULL) {
780 		/*
781 		 * Directly ship the packet on.  This allows forwarding
782 		 * packets originally destined to us to some other directly
783 		 * connected host.
784 		 */
785 		ip6_forward(m, 1);
786 		return;
787 	}
788 
789 passin:
790 	/*
791 	 * Disambiguate address scope zones (if there is ambiguity).
792 	 * We first make sure that the original source or destination address
793 	 * is not in our internal form for scoped addresses.  Such addresses
794 	 * are not necessarily invalid spec-wise, but we cannot accept them due
795 	 * to the usage conflict.
796 	 * in6_setscope() then also checks and rejects the cases where src or
797 	 * dst are the loopback address and the receiving interface
798 	 * is not loopback.
799 	 */
800 	if (in6_clearscope(&ip6->ip6_src) || in6_clearscope(&ip6->ip6_dst)) {
801 		IP6STAT_INC(ip6s_badscope); /* XXX */
802 		goto bad;
803 	}
804 	if (in6_setscope(&ip6->ip6_src, rcvif, NULL) ||
805 	    in6_setscope(&ip6->ip6_dst, rcvif, NULL)) {
806 		IP6STAT_INC(ip6s_badscope);
807 		goto bad;
808 	}
809 	/*
810 	 * Multicast check. Assume packet is for us to avoid
811 	 * prematurely taking locks.
812 	 */
813 	if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) {
814 		ours = 1;
815 		in6_ifstat_inc(rcvif, ifs6_in_mcast);
816 		goto hbhcheck;
817 	}
818 	/*
819 	 * Unicast check
820 	 * XXX: For now we keep link-local IPv6 addresses with embedded
821 	 *      scope zone id, therefore we use zero zoneid here.
822 	 */
823 	ia = in6ifa_ifwithaddr(&ip6->ip6_dst, 0 /* XXX */);
824 	if (ia != NULL) {
825 		if (ia->ia6_flags & IN6_IFF_NOTREADY) {
826 			char ip6bufs[INET6_ADDRSTRLEN];
827 			char ip6bufd[INET6_ADDRSTRLEN];
828 			/* address is not ready, so discard the packet. */
829 			nd6log((LOG_INFO,
830 			    "ip6_input: packet to an unready address %s->%s\n",
831 			    ip6_sprintf(ip6bufs, &ip6->ip6_src),
832 			    ip6_sprintf(ip6bufd, &ip6->ip6_dst)));
833 			ifa_free(&ia->ia_ifa);
834 			goto bad;
835 		}
836 		/* Count the packet in the ip address stats */
837 		counter_u64_add(ia->ia_ifa.ifa_ipackets, 1);
838 		counter_u64_add(ia->ia_ifa.ifa_ibytes, m->m_pkthdr.len);
839 		ifa_free(&ia->ia_ifa);
840 		ours = 1;
841 		goto hbhcheck;
842 	}
843 
844 	/*
845 	 * Now there is no reason to process the packet if it's not our own
846 	 * and we're not a router.
847 	 */
848 	if (!V_ip6_forwarding) {
849 		IP6STAT_INC(ip6s_cantforward);
850 		goto bad;
851 	}
852 
853   hbhcheck:
854 	/*
855 	 * Process Hop-by-Hop options header if it's contained.
856 	 * m may be modified in ip6_hopopts_input().
857 	 * If a JumboPayload option is included, plen will also be modified.
858 	 */
859 	plen = (u_int32_t)ntohs(ip6->ip6_plen);
860 	if (ip6->ip6_nxt == IPPROTO_HOPOPTS) {
861 		if (ip6_input_hbh(m, &plen, &rtalert, &off, &nxt, &ours) != 0)
862 			return;
863 	} else
864 		nxt = ip6->ip6_nxt;
865 
866 	/*
867 	 * Use mbuf flags to propagate Router Alert option to
868 	 * ICMPv6 layer, as hop-by-hop options have been stripped.
869 	 */
870 	if (rtalert != ~0)
871 		m->m_flags |= M_RTALERT_MLD;
872 
873 	/*
874 	 * Check that the amount of data in the buffers
875 	 * is as at least much as the IPv6 header would have us expect.
876 	 * Trim mbufs if longer than we expect.
877 	 * Drop packet if shorter than we expect.
878 	 */
879 	if (m->m_pkthdr.len - sizeof(struct ip6_hdr) < plen) {
880 		IP6STAT_INC(ip6s_tooshort);
881 		in6_ifstat_inc(rcvif, ifs6_in_truncated);
882 		goto bad;
883 	}
884 	if (m->m_pkthdr.len > sizeof(struct ip6_hdr) + plen) {
885 		if (m->m_len == m->m_pkthdr.len) {
886 			m->m_len = sizeof(struct ip6_hdr) + plen;
887 			m->m_pkthdr.len = sizeof(struct ip6_hdr) + plen;
888 		} else
889 			m_adj(m, sizeof(struct ip6_hdr) + plen - m->m_pkthdr.len);
890 	}
891 
892 	/*
893 	 * Forward if desirable.
894 	 */
895 	if (V_ip6_mrouter &&
896 	    IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) {
897 		/*
898 		 * If we are acting as a multicast router, all
899 		 * incoming multicast packets are passed to the
900 		 * kernel-level multicast forwarding function.
901 		 * The packet is returned (relatively) intact; if
902 		 * ip6_mforward() returns a non-zero value, the packet
903 		 * must be discarded, else it may be accepted below.
904 		 *
905 		 * XXX TODO: Check hlim and multicast scope here to avoid
906 		 * unnecessarily calling into ip6_mforward().
907 		 */
908 		if (ip6_mforward && ip6_mforward(ip6, rcvif, m)) {
909 			IP6STAT_INC(ip6s_cantforward);
910 			goto bad;
911 		}
912 	} else if (!ours) {
913 		ip6_forward(m, srcrt);
914 		return;
915 	}
916 
917 	ip6 = mtod(m, struct ip6_hdr *);
918 
919 	/*
920 	 * Malicious party may be able to use IPv4 mapped addr to confuse
921 	 * tcp/udp stack and bypass security checks (act as if it was from
922 	 * 127.0.0.1 by using IPv6 src ::ffff:127.0.0.1).  Be cautious.
923 	 *
924 	 * For SIIT end node behavior, you may want to disable the check.
925 	 * However, you will  become vulnerable to attacks using IPv4 mapped
926 	 * source.
927 	 */
928 	if (IN6_IS_ADDR_V4MAPPED(&ip6->ip6_src) ||
929 	    IN6_IS_ADDR_V4MAPPED(&ip6->ip6_dst)) {
930 		IP6STAT_INC(ip6s_badscope);
931 		in6_ifstat_inc(rcvif, ifs6_in_addrerr);
932 		goto bad;
933 	}
934 
935 	/*
936 	 * Tell launch routine the next header
937 	 */
938 	IP6STAT_INC(ip6s_delivered);
939 	in6_ifstat_inc(rcvif, ifs6_in_deliver);
940 	nest = 0;
941 
942 	while (nxt != IPPROTO_DONE) {
943 		if (V_ip6_hdrnestlimit && (++nest > V_ip6_hdrnestlimit)) {
944 			IP6STAT_INC(ip6s_toomanyhdr);
945 			goto bad;
946 		}
947 
948 		/*
949 		 * protection against faulty packet - there should be
950 		 * more sanity checks in header chain processing.
951 		 */
952 		if (m->m_pkthdr.len < off) {
953 			IP6STAT_INC(ip6s_tooshort);
954 			in6_ifstat_inc(rcvif, ifs6_in_truncated);
955 			goto bad;
956 		}
957 
958 #if defined(IPSEC) || defined(IPSEC_SUPPORT)
959 		if (IPSEC_ENABLED(ipv6)) {
960 			if (IPSEC_INPUT(ipv6, m, off, nxt) != 0)
961 				return;
962 		}
963 #endif /* IPSEC */
964 
965 		nxt = (*inet6sw[ip6_protox[nxt]].pr_input)(&m, &off, nxt);
966 	}
967 	return;
968 bad:
969 	in6_ifstat_inc(rcvif, ifs6_in_discard);
970 	if (m != NULL)
971 		m_freem(m);
972 }
973 
974 /*
975  * Hop-by-Hop options header processing. If a valid jumbo payload option is
976  * included, the real payload length will be stored in plenp.
977  *
978  * rtalertp - XXX: should be stored more smart way
979  */
980 static int
981 ip6_hopopts_input(u_int32_t *plenp, u_int32_t *rtalertp,
982     struct mbuf **mp, int *offp)
983 {
984 	struct mbuf *m = *mp;
985 	int off = *offp, hbhlen;
986 	struct ip6_hbh *hbh;
987 
988 	/* validation of the length of the header */
989 #ifndef PULLDOWN_TEST
990 	IP6_EXTHDR_CHECK(m, off, sizeof(*hbh), -1);
991 	hbh = (struct ip6_hbh *)(mtod(m, caddr_t) + off);
992 	hbhlen = (hbh->ip6h_len + 1) << 3;
993 
994 	IP6_EXTHDR_CHECK(m, off, hbhlen, -1);
995 	hbh = (struct ip6_hbh *)(mtod(m, caddr_t) + off);
996 #else
997 	IP6_EXTHDR_GET(hbh, struct ip6_hbh *, m,
998 		sizeof(struct ip6_hdr), sizeof(struct ip6_hbh));
999 	if (hbh == NULL) {
1000 		IP6STAT_INC(ip6s_tooshort);
1001 		return -1;
1002 	}
1003 	hbhlen = (hbh->ip6h_len + 1) << 3;
1004 	IP6_EXTHDR_GET(hbh, struct ip6_hbh *, m, sizeof(struct ip6_hdr),
1005 		hbhlen);
1006 	if (hbh == NULL) {
1007 		IP6STAT_INC(ip6s_tooshort);
1008 		return -1;
1009 	}
1010 #endif
1011 	off += hbhlen;
1012 	hbhlen -= sizeof(struct ip6_hbh);
1013 	if (ip6_process_hopopts(m, (u_int8_t *)hbh + sizeof(struct ip6_hbh),
1014 				hbhlen, rtalertp, plenp) < 0)
1015 		return (-1);
1016 
1017 	*offp = off;
1018 	*mp = m;
1019 	return (0);
1020 }
1021 
1022 /*
1023  * Search header for all Hop-by-hop options and process each option.
1024  * This function is separate from ip6_hopopts_input() in order to
1025  * handle a case where the sending node itself process its hop-by-hop
1026  * options header. In such a case, the function is called from ip6_output().
1027  *
1028  * The function assumes that hbh header is located right after the IPv6 header
1029  * (RFC2460 p7), opthead is pointer into data content in m, and opthead to
1030  * opthead + hbhlen is located in contiguous memory region.
1031  */
1032 int
1033 ip6_process_hopopts(struct mbuf *m, u_int8_t *opthead, int hbhlen,
1034     u_int32_t *rtalertp, u_int32_t *plenp)
1035 {
1036 	struct ip6_hdr *ip6;
1037 	int optlen = 0;
1038 	u_int8_t *opt = opthead;
1039 	u_int16_t rtalert_val;
1040 	u_int32_t jumboplen;
1041 	const int erroff = sizeof(struct ip6_hdr) + sizeof(struct ip6_hbh);
1042 
1043 	for (; hbhlen > 0; hbhlen -= optlen, opt += optlen) {
1044 		switch (*opt) {
1045 		case IP6OPT_PAD1:
1046 			optlen = 1;
1047 			break;
1048 		case IP6OPT_PADN:
1049 			if (hbhlen < IP6OPT_MINLEN) {
1050 				IP6STAT_INC(ip6s_toosmall);
1051 				goto bad;
1052 			}
1053 			optlen = *(opt + 1) + 2;
1054 			break;
1055 		case IP6OPT_ROUTER_ALERT:
1056 			/* XXX may need check for alignment */
1057 			if (hbhlen < IP6OPT_RTALERT_LEN) {
1058 				IP6STAT_INC(ip6s_toosmall);
1059 				goto bad;
1060 			}
1061 			if (*(opt + 1) != IP6OPT_RTALERT_LEN - 2) {
1062 				/* XXX stat */
1063 				icmp6_error(m, ICMP6_PARAM_PROB,
1064 				    ICMP6_PARAMPROB_HEADER,
1065 				    erroff + opt + 1 - opthead);
1066 				return (-1);
1067 			}
1068 			optlen = IP6OPT_RTALERT_LEN;
1069 			bcopy((caddr_t)(opt + 2), (caddr_t)&rtalert_val, 2);
1070 			*rtalertp = ntohs(rtalert_val);
1071 			break;
1072 		case IP6OPT_JUMBO:
1073 			/* XXX may need check for alignment */
1074 			if (hbhlen < IP6OPT_JUMBO_LEN) {
1075 				IP6STAT_INC(ip6s_toosmall);
1076 				goto bad;
1077 			}
1078 			if (*(opt + 1) != IP6OPT_JUMBO_LEN - 2) {
1079 				/* XXX stat */
1080 				icmp6_error(m, ICMP6_PARAM_PROB,
1081 				    ICMP6_PARAMPROB_HEADER,
1082 				    erroff + opt + 1 - opthead);
1083 				return (-1);
1084 			}
1085 			optlen = IP6OPT_JUMBO_LEN;
1086 
1087 			/*
1088 			 * IPv6 packets that have non 0 payload length
1089 			 * must not contain a jumbo payload option.
1090 			 */
1091 			ip6 = mtod(m, struct ip6_hdr *);
1092 			if (ip6->ip6_plen) {
1093 				IP6STAT_INC(ip6s_badoptions);
1094 				icmp6_error(m, ICMP6_PARAM_PROB,
1095 				    ICMP6_PARAMPROB_HEADER,
1096 				    erroff + opt - opthead);
1097 				return (-1);
1098 			}
1099 
1100 			/*
1101 			 * We may see jumbolen in unaligned location, so
1102 			 * we'd need to perform bcopy().
1103 			 */
1104 			bcopy(opt + 2, &jumboplen, sizeof(jumboplen));
1105 			jumboplen = (u_int32_t)htonl(jumboplen);
1106 
1107 #if 1
1108 			/*
1109 			 * if there are multiple jumbo payload options,
1110 			 * *plenp will be non-zero and the packet will be
1111 			 * rejected.
1112 			 * the behavior may need some debate in ipngwg -
1113 			 * multiple options does not make sense, however,
1114 			 * there's no explicit mention in specification.
1115 			 */
1116 			if (*plenp != 0) {
1117 				IP6STAT_INC(ip6s_badoptions);
1118 				icmp6_error(m, ICMP6_PARAM_PROB,
1119 				    ICMP6_PARAMPROB_HEADER,
1120 				    erroff + opt + 2 - opthead);
1121 				return (-1);
1122 			}
1123 #endif
1124 
1125 			/*
1126 			 * jumbo payload length must be larger than 65535.
1127 			 */
1128 			if (jumboplen <= IPV6_MAXPACKET) {
1129 				IP6STAT_INC(ip6s_badoptions);
1130 				icmp6_error(m, ICMP6_PARAM_PROB,
1131 				    ICMP6_PARAMPROB_HEADER,
1132 				    erroff + opt + 2 - opthead);
1133 				return (-1);
1134 			}
1135 			*plenp = jumboplen;
1136 
1137 			break;
1138 		default:		/* unknown option */
1139 			if (hbhlen < IP6OPT_MINLEN) {
1140 				IP6STAT_INC(ip6s_toosmall);
1141 				goto bad;
1142 			}
1143 			optlen = ip6_unknown_opt(opt, m,
1144 			    erroff + opt - opthead);
1145 			if (optlen == -1)
1146 				return (-1);
1147 			optlen += 2;
1148 			break;
1149 		}
1150 	}
1151 
1152 	return (0);
1153 
1154   bad:
1155 	m_freem(m);
1156 	return (-1);
1157 }
1158 
1159 /*
1160  * Unknown option processing.
1161  * The third argument `off' is the offset from the IPv6 header to the option,
1162  * which is necessary if the IPv6 header the and option header and IPv6 header
1163  * is not contiguous in order to return an ICMPv6 error.
1164  */
1165 int
1166 ip6_unknown_opt(u_int8_t *optp, struct mbuf *m, int off)
1167 {
1168 	struct ip6_hdr *ip6;
1169 
1170 	switch (IP6OPT_TYPE(*optp)) {
1171 	case IP6OPT_TYPE_SKIP: /* ignore the option */
1172 		return ((int)*(optp + 1));
1173 	case IP6OPT_TYPE_DISCARD:	/* silently discard */
1174 		m_freem(m);
1175 		return (-1);
1176 	case IP6OPT_TYPE_FORCEICMP: /* send ICMP even if multicasted */
1177 		IP6STAT_INC(ip6s_badoptions);
1178 		icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_OPTION, off);
1179 		return (-1);
1180 	case IP6OPT_TYPE_ICMP: /* send ICMP if not multicasted */
1181 		IP6STAT_INC(ip6s_badoptions);
1182 		ip6 = mtod(m, struct ip6_hdr *);
1183 		if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) ||
1184 		    (m->m_flags & (M_BCAST|M_MCAST)))
1185 			m_freem(m);
1186 		else
1187 			icmp6_error(m, ICMP6_PARAM_PROB,
1188 				    ICMP6_PARAMPROB_OPTION, off);
1189 		return (-1);
1190 	}
1191 
1192 	m_freem(m);		/* XXX: NOTREACHED */
1193 	return (-1);
1194 }
1195 
1196 /*
1197  * Create the "control" list for this pcb.
1198  * These functions will not modify mbuf chain at all.
1199  *
1200  * With KAME mbuf chain restriction:
1201  * The routine will be called from upper layer handlers like tcp6_input().
1202  * Thus the routine assumes that the caller (tcp6_input) have already
1203  * called IP6_EXTHDR_CHECK() and all the extension headers are located in the
1204  * very first mbuf on the mbuf chain.
1205  *
1206  * ip6_savecontrol_v4 will handle those options that are possible to be
1207  * set on a v4-mapped socket.
1208  * ip6_savecontrol will directly call ip6_savecontrol_v4 to handle those
1209  * options and handle the v6-only ones itself.
1210  */
1211 struct mbuf **
1212 ip6_savecontrol_v4(struct inpcb *inp, struct mbuf *m, struct mbuf **mp,
1213     int *v4only)
1214 {
1215 	struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
1216 
1217 #ifdef SO_TIMESTAMP
1218 	if ((inp->inp_socket->so_options & SO_TIMESTAMP) != 0) {
1219 		union {
1220 			struct timeval tv;
1221 			struct bintime bt;
1222 			struct timespec ts;
1223 		} t;
1224 		struct bintime boottimebin, bt1;
1225 		struct timespec ts1;
1226 		bool stamped;
1227 
1228 		stamped = false;
1229 		switch (inp->inp_socket->so_ts_clock) {
1230 		case SO_TS_REALTIME_MICRO:
1231 			if ((m->m_flags & (M_PKTHDR | M_TSTMP)) == (M_PKTHDR |
1232 			    M_TSTMP)) {
1233 				mbuf_tstmp2timespec(m, &ts1);
1234 				timespec2bintime(&ts1, &bt1);
1235 				getboottimebin(&boottimebin);
1236 				bintime_add(&bt1, &boottimebin);
1237 				bintime2timeval(&bt1, &t.tv);
1238 			} else {
1239 				microtime(&t.tv);
1240 			}
1241 			*mp = sbcreatecontrol((caddr_t) &t.tv, sizeof(t.tv),
1242 			    SCM_TIMESTAMP, SOL_SOCKET);
1243 			if (*mp != NULL) {
1244 				mp = &(*mp)->m_next;
1245 				stamped = true;
1246 			}
1247 			break;
1248 
1249 		case SO_TS_BINTIME:
1250 			if ((m->m_flags & (M_PKTHDR | M_TSTMP)) == (M_PKTHDR |
1251 			    M_TSTMP)) {
1252 				mbuf_tstmp2timespec(m, &ts1);
1253 				timespec2bintime(&ts1, &t.bt);
1254 				getboottimebin(&boottimebin);
1255 				bintime_add(&t.bt, &boottimebin);
1256 			} else {
1257 				bintime(&t.bt);
1258 			}
1259 			*mp = sbcreatecontrol((caddr_t)&t.bt, sizeof(t.bt),
1260 			    SCM_BINTIME, SOL_SOCKET);
1261 			if (*mp != NULL) {
1262 				mp = &(*mp)->m_next;
1263 				stamped = true;
1264 			}
1265 			break;
1266 
1267 		case SO_TS_REALTIME:
1268 			if ((m->m_flags & (M_PKTHDR | M_TSTMP)) == (M_PKTHDR |
1269 			    M_TSTMP)) {
1270 				mbuf_tstmp2timespec(m, &t.ts);
1271 				getboottimebin(&boottimebin);
1272 				bintime2timespec(&boottimebin, &ts1);
1273 				timespecadd(&t.ts, &ts1);
1274 			} else {
1275 				nanotime(&t.ts);
1276 			}
1277 			*mp = sbcreatecontrol((caddr_t)&t.ts, sizeof(t.ts),
1278 			    SCM_REALTIME, SOL_SOCKET);
1279 			if (*mp != NULL) {
1280 				mp = &(*mp)->m_next;
1281 				stamped = true;
1282 			}
1283 			break;
1284 
1285 		case SO_TS_MONOTONIC:
1286 			if ((m->m_flags & (M_PKTHDR | M_TSTMP)) == (M_PKTHDR |
1287 			    M_TSTMP))
1288 				mbuf_tstmp2timespec(m, &t.ts);
1289 			else
1290 				nanouptime(&t.ts);
1291 			*mp = sbcreatecontrol((caddr_t)&t.ts, sizeof(t.ts),
1292 			    SCM_MONOTONIC, SOL_SOCKET);
1293 			if (*mp != NULL) {
1294 				mp = &(*mp)->m_next;
1295 				stamped = true;
1296 			}
1297 			break;
1298 
1299 		default:
1300 			panic("unknown (corrupted) so_ts_clock");
1301 		}
1302 		if (stamped && (m->m_flags & (M_PKTHDR | M_TSTMP)) ==
1303 		    (M_PKTHDR | M_TSTMP)) {
1304 			struct sock_timestamp_info sti;
1305 
1306 			bzero(&sti, sizeof(sti));
1307 			sti.st_info_flags = ST_INFO_HW;
1308 			if ((m->m_flags & M_TSTMP_HPREC) != 0)
1309 				sti.st_info_flags |= ST_INFO_HW_HPREC;
1310 			*mp = sbcreatecontrol((caddr_t)&sti, sizeof(sti),
1311 			    SCM_TIME_INFO, SOL_SOCKET);
1312 			if (*mp != NULL)
1313 				mp = &(*mp)->m_next;
1314 		}
1315 	}
1316 #endif
1317 
1318 #define IS2292(inp, x, y)	(((inp)->inp_flags & IN6P_RFC2292) ? (x) : (y))
1319 	/* RFC 2292 sec. 5 */
1320 	if ((inp->inp_flags & IN6P_PKTINFO) != 0) {
1321 		struct in6_pktinfo pi6;
1322 
1323 		if ((ip6->ip6_vfc & IPV6_VERSION_MASK) != IPV6_VERSION) {
1324 #ifdef INET
1325 			struct ip *ip;
1326 
1327 			ip = mtod(m, struct ip *);
1328 			pi6.ipi6_addr.s6_addr32[0] = 0;
1329 			pi6.ipi6_addr.s6_addr32[1] = 0;
1330 			pi6.ipi6_addr.s6_addr32[2] = IPV6_ADDR_INT32_SMP;
1331 			pi6.ipi6_addr.s6_addr32[3] = ip->ip_dst.s_addr;
1332 #else
1333 			/* We won't hit this code */
1334 			bzero(&pi6.ipi6_addr, sizeof(struct in6_addr));
1335 #endif
1336 		} else {
1337 			bcopy(&ip6->ip6_dst, &pi6.ipi6_addr, sizeof(struct in6_addr));
1338 			in6_clearscope(&pi6.ipi6_addr);	/* XXX */
1339 		}
1340 		pi6.ipi6_ifindex =
1341 		    (m && m->m_pkthdr.rcvif) ? m->m_pkthdr.rcvif->if_index : 0;
1342 
1343 		*mp = sbcreatecontrol((caddr_t) &pi6,
1344 		    sizeof(struct in6_pktinfo),
1345 		    IS2292(inp, IPV6_2292PKTINFO, IPV6_PKTINFO), IPPROTO_IPV6);
1346 		if (*mp)
1347 			mp = &(*mp)->m_next;
1348 	}
1349 
1350 	if ((inp->inp_flags & IN6P_HOPLIMIT) != 0) {
1351 		int hlim;
1352 
1353 		if ((ip6->ip6_vfc & IPV6_VERSION_MASK) != IPV6_VERSION) {
1354 #ifdef INET
1355 			struct ip *ip;
1356 
1357 			ip = mtod(m, struct ip *);
1358 			hlim = ip->ip_ttl;
1359 #else
1360 			/* We won't hit this code */
1361 			hlim = 0;
1362 #endif
1363 		} else {
1364 			hlim = ip6->ip6_hlim & 0xff;
1365 		}
1366 		*mp = sbcreatecontrol((caddr_t) &hlim, sizeof(int),
1367 		    IS2292(inp, IPV6_2292HOPLIMIT, IPV6_HOPLIMIT),
1368 		    IPPROTO_IPV6);
1369 		if (*mp)
1370 			mp = &(*mp)->m_next;
1371 	}
1372 
1373 	if ((inp->inp_flags & IN6P_TCLASS) != 0) {
1374 		int tclass;
1375 
1376 		if ((ip6->ip6_vfc & IPV6_VERSION_MASK) != IPV6_VERSION) {
1377 #ifdef INET
1378 			struct ip *ip;
1379 
1380 			ip = mtod(m, struct ip *);
1381 			tclass = ip->ip_tos;
1382 #else
1383 			/* We won't hit this code */
1384 			tclass = 0;
1385 #endif
1386 		} else {
1387 			u_int32_t flowinfo;
1388 
1389 			flowinfo = (u_int32_t)ntohl(ip6->ip6_flow & IPV6_FLOWINFO_MASK);
1390 			flowinfo >>= 20;
1391 			tclass = flowinfo & 0xff;
1392 		}
1393 		*mp = sbcreatecontrol((caddr_t) &tclass, sizeof(int),
1394 		    IPV6_TCLASS, IPPROTO_IPV6);
1395 		if (*mp)
1396 			mp = &(*mp)->m_next;
1397 	}
1398 
1399 	if (v4only != NULL) {
1400 		if ((ip6->ip6_vfc & IPV6_VERSION_MASK) != IPV6_VERSION) {
1401 			*v4only = 1;
1402 		} else {
1403 			*v4only = 0;
1404 		}
1405 	}
1406 
1407 	return (mp);
1408 }
1409 
1410 void
1411 ip6_savecontrol(struct inpcb *in6p, struct mbuf *m, struct mbuf **mp)
1412 {
1413 	struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
1414 	int v4only = 0;
1415 
1416 	mp = ip6_savecontrol_v4(in6p, m, mp, &v4only);
1417 	if (v4only)
1418 		return;
1419 
1420 	/*
1421 	 * IPV6_HOPOPTS socket option.  Recall that we required super-user
1422 	 * privilege for the option (see ip6_ctloutput), but it might be too
1423 	 * strict, since there might be some hop-by-hop options which can be
1424 	 * returned to normal user.
1425 	 * See also RFC 2292 section 6 (or RFC 3542 section 8).
1426 	 */
1427 	if ((in6p->inp_flags & IN6P_HOPOPTS) != 0) {
1428 		/*
1429 		 * Check if a hop-by-hop options header is contatined in the
1430 		 * received packet, and if so, store the options as ancillary
1431 		 * data. Note that a hop-by-hop options header must be
1432 		 * just after the IPv6 header, which is assured through the
1433 		 * IPv6 input processing.
1434 		 */
1435 		if (ip6->ip6_nxt == IPPROTO_HOPOPTS) {
1436 			struct ip6_hbh *hbh;
1437 			int hbhlen = 0;
1438 #ifdef PULLDOWN_TEST
1439 			struct mbuf *ext;
1440 #endif
1441 
1442 #ifndef PULLDOWN_TEST
1443 			hbh = (struct ip6_hbh *)(ip6 + 1);
1444 			hbhlen = (hbh->ip6h_len + 1) << 3;
1445 #else
1446 			ext = ip6_pullexthdr(m, sizeof(struct ip6_hdr),
1447 			    ip6->ip6_nxt);
1448 			if (ext == NULL) {
1449 				IP6STAT_INC(ip6s_tooshort);
1450 				return;
1451 			}
1452 			hbh = mtod(ext, struct ip6_hbh *);
1453 			hbhlen = (hbh->ip6h_len + 1) << 3;
1454 			if (hbhlen != ext->m_len) {
1455 				m_freem(ext);
1456 				IP6STAT_INC(ip6s_tooshort);
1457 				return;
1458 			}
1459 #endif
1460 
1461 			/*
1462 			 * XXX: We copy the whole header even if a
1463 			 * jumbo payload option is included, the option which
1464 			 * is to be removed before returning according to
1465 			 * RFC2292.
1466 			 * Note: this constraint is removed in RFC3542
1467 			 */
1468 			*mp = sbcreatecontrol((caddr_t)hbh, hbhlen,
1469 			    IS2292(in6p, IPV6_2292HOPOPTS, IPV6_HOPOPTS),
1470 			    IPPROTO_IPV6);
1471 			if (*mp)
1472 				mp = &(*mp)->m_next;
1473 #ifdef PULLDOWN_TEST
1474 			m_freem(ext);
1475 #endif
1476 		}
1477 	}
1478 
1479 	if ((in6p->inp_flags & (IN6P_RTHDR | IN6P_DSTOPTS)) != 0) {
1480 		int nxt = ip6->ip6_nxt, off = sizeof(struct ip6_hdr);
1481 
1482 		/*
1483 		 * Search for destination options headers or routing
1484 		 * header(s) through the header chain, and stores each
1485 		 * header as ancillary data.
1486 		 * Note that the order of the headers remains in
1487 		 * the chain of ancillary data.
1488 		 */
1489 		while (1) {	/* is explicit loop prevention necessary? */
1490 			struct ip6_ext *ip6e = NULL;
1491 			int elen;
1492 #ifdef PULLDOWN_TEST
1493 			struct mbuf *ext = NULL;
1494 #endif
1495 
1496 			/*
1497 			 * if it is not an extension header, don't try to
1498 			 * pull it from the chain.
1499 			 */
1500 			switch (nxt) {
1501 			case IPPROTO_DSTOPTS:
1502 			case IPPROTO_ROUTING:
1503 			case IPPROTO_HOPOPTS:
1504 			case IPPROTO_AH: /* is it possible? */
1505 				break;
1506 			default:
1507 				goto loopend;
1508 			}
1509 
1510 #ifndef PULLDOWN_TEST
1511 			if (off + sizeof(*ip6e) > m->m_len)
1512 				goto loopend;
1513 			ip6e = (struct ip6_ext *)(mtod(m, caddr_t) + off);
1514 			if (nxt == IPPROTO_AH)
1515 				elen = (ip6e->ip6e_len + 2) << 2;
1516 			else
1517 				elen = (ip6e->ip6e_len + 1) << 3;
1518 			if (off + elen > m->m_len)
1519 				goto loopend;
1520 #else
1521 			ext = ip6_pullexthdr(m, off, nxt);
1522 			if (ext == NULL) {
1523 				IP6STAT_INC(ip6s_tooshort);
1524 				return;
1525 			}
1526 			ip6e = mtod(ext, struct ip6_ext *);
1527 			if (nxt == IPPROTO_AH)
1528 				elen = (ip6e->ip6e_len + 2) << 2;
1529 			else
1530 				elen = (ip6e->ip6e_len + 1) << 3;
1531 			if (elen != ext->m_len) {
1532 				m_freem(ext);
1533 				IP6STAT_INC(ip6s_tooshort);
1534 				return;
1535 			}
1536 #endif
1537 
1538 			switch (nxt) {
1539 			case IPPROTO_DSTOPTS:
1540 				if (!(in6p->inp_flags & IN6P_DSTOPTS))
1541 					break;
1542 
1543 				*mp = sbcreatecontrol((caddr_t)ip6e, elen,
1544 				    IS2292(in6p,
1545 					IPV6_2292DSTOPTS, IPV6_DSTOPTS),
1546 				    IPPROTO_IPV6);
1547 				if (*mp)
1548 					mp = &(*mp)->m_next;
1549 				break;
1550 			case IPPROTO_ROUTING:
1551 				if (!(in6p->inp_flags & IN6P_RTHDR))
1552 					break;
1553 
1554 				*mp = sbcreatecontrol((caddr_t)ip6e, elen,
1555 				    IS2292(in6p, IPV6_2292RTHDR, IPV6_RTHDR),
1556 				    IPPROTO_IPV6);
1557 				if (*mp)
1558 					mp = &(*mp)->m_next;
1559 				break;
1560 			case IPPROTO_HOPOPTS:
1561 			case IPPROTO_AH: /* is it possible? */
1562 				break;
1563 
1564 			default:
1565 				/*
1566 				 * other cases have been filtered in the above.
1567 				 * none will visit this case.  here we supply
1568 				 * the code just in case (nxt overwritten or
1569 				 * other cases).
1570 				 */
1571 #ifdef PULLDOWN_TEST
1572 				m_freem(ext);
1573 #endif
1574 				goto loopend;
1575 
1576 			}
1577 
1578 			/* proceed with the next header. */
1579 			off += elen;
1580 			nxt = ip6e->ip6e_nxt;
1581 			ip6e = NULL;
1582 #ifdef PULLDOWN_TEST
1583 			m_freem(ext);
1584 			ext = NULL;
1585 #endif
1586 		}
1587 	  loopend:
1588 		;
1589 	}
1590 
1591 	if (in6p->inp_flags2 & INP_RECVFLOWID) {
1592 		uint32_t flowid, flow_type;
1593 
1594 		flowid = m->m_pkthdr.flowid;
1595 		flow_type = M_HASHTYPE_GET(m);
1596 
1597 		/*
1598 		 * XXX should handle the failure of one or the
1599 		 * other - don't populate both?
1600 		 */
1601 		*mp = sbcreatecontrol((caddr_t) &flowid,
1602 		    sizeof(uint32_t), IPV6_FLOWID, IPPROTO_IPV6);
1603 		if (*mp)
1604 			mp = &(*mp)->m_next;
1605 		*mp = sbcreatecontrol((caddr_t) &flow_type,
1606 		    sizeof(uint32_t), IPV6_FLOWTYPE, IPPROTO_IPV6);
1607 		if (*mp)
1608 			mp = &(*mp)->m_next;
1609 	}
1610 
1611 #ifdef	RSS
1612 	if (in6p->inp_flags2 & INP_RECVRSSBUCKETID) {
1613 		uint32_t flowid, flow_type;
1614 		uint32_t rss_bucketid;
1615 
1616 		flowid = m->m_pkthdr.flowid;
1617 		flow_type = M_HASHTYPE_GET(m);
1618 
1619 		if (rss_hash2bucket(flowid, flow_type, &rss_bucketid) == 0) {
1620 			*mp = sbcreatecontrol((caddr_t) &rss_bucketid,
1621 			   sizeof(uint32_t), IPV6_RSSBUCKETID, IPPROTO_IPV6);
1622 			if (*mp)
1623 				mp = &(*mp)->m_next;
1624 		}
1625 	}
1626 #endif
1627 
1628 }
1629 #undef IS2292
1630 
1631 void
1632 ip6_notify_pmtu(struct inpcb *inp, struct sockaddr_in6 *dst, u_int32_t mtu)
1633 {
1634 	struct socket *so;
1635 	struct mbuf *m_mtu;
1636 	struct ip6_mtuinfo mtuctl;
1637 
1638 	KASSERT(inp != NULL, ("%s: inp == NULL", __func__));
1639 	/*
1640 	 * Notify the error by sending IPV6_PATHMTU ancillary data if
1641 	 * application wanted to know the MTU value.
1642 	 * NOTE: we notify disconnected sockets, because some udp
1643 	 * applications keep sending sockets disconnected.
1644 	 * NOTE: our implementation doesn't notify connected sockets that has
1645 	 * foreign address that is different than given destination addresses
1646 	 * (this is permitted by RFC 3542).
1647 	 */
1648 	if ((inp->inp_flags & IN6P_MTU) == 0 || (
1649 	    !IN6_IS_ADDR_UNSPECIFIED(&inp->in6p_faddr) &&
1650 	    !IN6_ARE_ADDR_EQUAL(&inp->in6p_faddr, &dst->sin6_addr)))
1651 		return;
1652 
1653 	mtuctl.ip6m_mtu = mtu;
1654 	mtuctl.ip6m_addr = *dst;
1655 	if (sa6_recoverscope(&mtuctl.ip6m_addr))
1656 		return;
1657 
1658 	if ((m_mtu = sbcreatecontrol((caddr_t)&mtuctl, sizeof(mtuctl),
1659 	    IPV6_PATHMTU, IPPROTO_IPV6)) == NULL)
1660 		return;
1661 
1662 	so =  inp->inp_socket;
1663 	if (sbappendaddr(&so->so_rcv, (struct sockaddr *)dst, NULL, m_mtu)
1664 	    == 0) {
1665 		m_freem(m_mtu);
1666 		/* XXX: should count statistics */
1667 	} else
1668 		sorwakeup(so);
1669 }
1670 
1671 #ifdef PULLDOWN_TEST
1672 /*
1673  * pull single extension header from mbuf chain.  returns single mbuf that
1674  * contains the result, or NULL on error.
1675  */
1676 static struct mbuf *
1677 ip6_pullexthdr(struct mbuf *m, size_t off, int nxt)
1678 {
1679 	struct ip6_ext ip6e;
1680 	size_t elen;
1681 	struct mbuf *n;
1682 
1683 #ifdef DIAGNOSTIC
1684 	switch (nxt) {
1685 	case IPPROTO_DSTOPTS:
1686 	case IPPROTO_ROUTING:
1687 	case IPPROTO_HOPOPTS:
1688 	case IPPROTO_AH: /* is it possible? */
1689 		break;
1690 	default:
1691 		printf("ip6_pullexthdr: invalid nxt=%d\n", nxt);
1692 	}
1693 #endif
1694 
1695 	m_copydata(m, off, sizeof(ip6e), (caddr_t)&ip6e);
1696 	if (nxt == IPPROTO_AH)
1697 		elen = (ip6e.ip6e_len + 2) << 2;
1698 	else
1699 		elen = (ip6e.ip6e_len + 1) << 3;
1700 
1701 	if (elen > MLEN)
1702 		n = m_getcl(M_NOWAIT, MT_DATA, 0);
1703 	else
1704 		n = m_get(M_NOWAIT, MT_DATA);
1705 	if (n == NULL)
1706 		return NULL;
1707 
1708 	m_copydata(m, off, elen, mtod(n, caddr_t));
1709 	n->m_len = elen;
1710 	return n;
1711 }
1712 #endif
1713 
1714 /*
1715  * Get pointer to the previous header followed by the header
1716  * currently processed.
1717  * XXX: This function supposes that
1718  *	M includes all headers,
1719  *	the next header field and the header length field of each header
1720  *	are valid, and
1721  *	the sum of each header length equals to OFF.
1722  * Because of these assumptions, this function must be called very
1723  * carefully. Moreover, it will not be used in the near future when
1724  * we develop `neater' mechanism to process extension headers.
1725  */
1726 char *
1727 ip6_get_prevhdr(const struct mbuf *m, int off)
1728 {
1729 	struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
1730 
1731 	if (off == sizeof(struct ip6_hdr))
1732 		return (&ip6->ip6_nxt);
1733 	else {
1734 		int len, nxt;
1735 		struct ip6_ext *ip6e = NULL;
1736 
1737 		nxt = ip6->ip6_nxt;
1738 		len = sizeof(struct ip6_hdr);
1739 		while (len < off) {
1740 			ip6e = (struct ip6_ext *)(mtod(m, caddr_t) + len);
1741 
1742 			switch (nxt) {
1743 			case IPPROTO_FRAGMENT:
1744 				len += sizeof(struct ip6_frag);
1745 				break;
1746 			case IPPROTO_AH:
1747 				len += (ip6e->ip6e_len + 2) << 2;
1748 				break;
1749 			default:
1750 				len += (ip6e->ip6e_len + 1) << 3;
1751 				break;
1752 			}
1753 			nxt = ip6e->ip6e_nxt;
1754 		}
1755 		if (ip6e)
1756 			return (&ip6e->ip6e_nxt);
1757 		else
1758 			return NULL;
1759 	}
1760 }
1761 
1762 /*
1763  * get next header offset.  m will be retained.
1764  */
1765 int
1766 ip6_nexthdr(const struct mbuf *m, int off, int proto, int *nxtp)
1767 {
1768 	struct ip6_hdr ip6;
1769 	struct ip6_ext ip6e;
1770 	struct ip6_frag fh;
1771 
1772 	/* just in case */
1773 	if (m == NULL)
1774 		panic("ip6_nexthdr: m == NULL");
1775 	if ((m->m_flags & M_PKTHDR) == 0 || m->m_pkthdr.len < off)
1776 		return -1;
1777 
1778 	switch (proto) {
1779 	case IPPROTO_IPV6:
1780 		if (m->m_pkthdr.len < off + sizeof(ip6))
1781 			return -1;
1782 		m_copydata(m, off, sizeof(ip6), (caddr_t)&ip6);
1783 		if (nxtp)
1784 			*nxtp = ip6.ip6_nxt;
1785 		off += sizeof(ip6);
1786 		return off;
1787 
1788 	case IPPROTO_FRAGMENT:
1789 		/*
1790 		 * terminate parsing if it is not the first fragment,
1791 		 * it does not make sense to parse through it.
1792 		 */
1793 		if (m->m_pkthdr.len < off + sizeof(fh))
1794 			return -1;
1795 		m_copydata(m, off, sizeof(fh), (caddr_t)&fh);
1796 		/* IP6F_OFF_MASK = 0xfff8(BigEndian), 0xf8ff(LittleEndian) */
1797 		if (fh.ip6f_offlg & IP6F_OFF_MASK)
1798 			return -1;
1799 		if (nxtp)
1800 			*nxtp = fh.ip6f_nxt;
1801 		off += sizeof(struct ip6_frag);
1802 		return off;
1803 
1804 	case IPPROTO_AH:
1805 		if (m->m_pkthdr.len < off + sizeof(ip6e))
1806 			return -1;
1807 		m_copydata(m, off, sizeof(ip6e), (caddr_t)&ip6e);
1808 		if (nxtp)
1809 			*nxtp = ip6e.ip6e_nxt;
1810 		off += (ip6e.ip6e_len + 2) << 2;
1811 		return off;
1812 
1813 	case IPPROTO_HOPOPTS:
1814 	case IPPROTO_ROUTING:
1815 	case IPPROTO_DSTOPTS:
1816 		if (m->m_pkthdr.len < off + sizeof(ip6e))
1817 			return -1;
1818 		m_copydata(m, off, sizeof(ip6e), (caddr_t)&ip6e);
1819 		if (nxtp)
1820 			*nxtp = ip6e.ip6e_nxt;
1821 		off += (ip6e.ip6e_len + 1) << 3;
1822 		return off;
1823 
1824 	case IPPROTO_NONE:
1825 	case IPPROTO_ESP:
1826 	case IPPROTO_IPCOMP:
1827 		/* give up */
1828 		return -1;
1829 
1830 	default:
1831 		return -1;
1832 	}
1833 
1834 	/* NOTREACHED */
1835 }
1836 
1837 /*
1838  * get offset for the last header in the chain.  m will be kept untainted.
1839  */
1840 int
1841 ip6_lasthdr(const struct mbuf *m, int off, int proto, int *nxtp)
1842 {
1843 	int newoff;
1844 	int nxt;
1845 
1846 	if (!nxtp) {
1847 		nxt = -1;
1848 		nxtp = &nxt;
1849 	}
1850 	while (1) {
1851 		newoff = ip6_nexthdr(m, off, proto, nxtp);
1852 		if (newoff < 0)
1853 			return off;
1854 		else if (newoff < off)
1855 			return -1;	/* invalid */
1856 		else if (newoff == off)
1857 			return newoff;
1858 
1859 		off = newoff;
1860 		proto = *nxtp;
1861 	}
1862 }
1863 
1864 /*
1865  * System control for IP6
1866  */
1867 
1868 u_char	inet6ctlerrmap[PRC_NCMDS] = {
1869 	0,		0,		0,		0,
1870 	0,		EMSGSIZE,	EHOSTDOWN,	EHOSTUNREACH,
1871 	EHOSTUNREACH,	EHOSTUNREACH,	ECONNREFUSED,	ECONNREFUSED,
1872 	EMSGSIZE,	EHOSTUNREACH,	0,		0,
1873 	0,		0,		EHOSTUNREACH,	0,
1874 	ENOPROTOOPT,	ECONNREFUSED
1875 };
1876