xref: /freebsd/sys/netinet6/ip6_input.c (revision 045c8f526484cb3b97f5fd693987f4376fa43c5f)
1 /*-
2  * SPDX-License-Identifier: BSD-3-Clause
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  *	$KAME: ip6_input.c,v 1.259 2002/01/21 04:58:09 jinmei Exp $
32  */
33 
34 /*-
35  * Copyright (c) 1982, 1986, 1988, 1993
36  *	The Regents of the University of California.  All rights reserved.
37  *
38  * Redistribution and use in source and binary forms, with or without
39  * modification, are permitted provided that the following conditions
40  * are met:
41  * 1. Redistributions of source code must retain the above copyright
42  *    notice, this list of conditions and the following disclaimer.
43  * 2. Redistributions in binary form must reproduce the above copyright
44  *    notice, this list of conditions and the following disclaimer in the
45  *    documentation and/or other materials provided with the distribution.
46  * 3. Neither the name of the University nor the names of its contributors
47  *    may be used to endorse or promote products derived from this software
48  *    without specific prior written permission.
49  *
50  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
51  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
52  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
53  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
54  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
55  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
56  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
57  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
58  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
59  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
60  * SUCH DAMAGE.
61  *
62  *	@(#)ip_input.c	8.2 (Berkeley) 1/4/94
63  */
64 
65 #include <sys/cdefs.h>
66 __FBSDID("$FreeBSD$");
67 
68 #include "opt_inet.h"
69 #include "opt_inet6.h"
70 #include "opt_ipsec.h"
71 #include "opt_route.h"
72 #include "opt_rss.h"
73 
74 #include <sys/param.h>
75 #include <sys/systm.h>
76 #include <sys/hhook.h>
77 #include <sys/malloc.h>
78 #include <sys/mbuf.h>
79 #include <sys/proc.h>
80 #include <sys/domain.h>
81 #include <sys/protosw.h>
82 #include <sys/sdt.h>
83 #include <sys/socket.h>
84 #include <sys/socketvar.h>
85 #include <sys/errno.h>
86 #include <sys/time.h>
87 #include <sys/kernel.h>
88 #include <sys/lock.h>
89 #include <sys/rmlock.h>
90 #include <sys/syslog.h>
91 #include <sys/sysctl.h>
92 
93 #include <net/if.h>
94 #include <net/if_var.h>
95 #include <net/if_types.h>
96 #include <net/if_dl.h>
97 #include <net/route.h>
98 #include <net/netisr.h>
99 #include <net/rss_config.h>
100 #include <net/pfil.h>
101 #include <net/vnet.h>
102 
103 #include <netinet/in.h>
104 #include <netinet/in_kdtrace.h>
105 #include <netinet/ip_var.h>
106 #include <netinet/in_systm.h>
107 #include <net/if_llatbl.h>
108 #ifdef INET
109 #include <netinet/ip.h>
110 #include <netinet/ip_icmp.h>
111 #endif /* INET */
112 #include <netinet/ip6.h>
113 #include <netinet6/in6_var.h>
114 #include <netinet6/ip6_var.h>
115 #include <netinet/in_pcb.h>
116 #include <netinet/icmp6.h>
117 #include <netinet6/scope6_var.h>
118 #include <netinet6/in6_ifattach.h>
119 #include <netinet6/mld6_var.h>
120 #include <netinet6/nd6.h>
121 #include <netinet6/in6_rss.h>
122 
123 #include <netipsec/ipsec_support.h>
124 
125 #include <netinet6/ip6protosw.h>
126 
127 extern struct domain inet6domain;
128 
129 u_char ip6_protox[IPPROTO_MAX];
130 VNET_DEFINE(struct in6_ifaddrhead, in6_ifaddrhead);
131 VNET_DEFINE(struct in6_ifaddrlisthead *, in6_ifaddrhashtbl);
132 VNET_DEFINE(u_long, in6_ifaddrhmask);
133 
134 static struct netisr_handler ip6_nh = {
135 	.nh_name = "ip6",
136 	.nh_handler = ip6_input,
137 	.nh_proto = NETISR_IPV6,
138 #ifdef RSS
139 	.nh_m2cpuid = rss_soft_m2cpuid_v6,
140 	.nh_policy = NETISR_POLICY_CPU,
141 	.nh_dispatch = NETISR_DISPATCH_HYBRID,
142 #else
143 	.nh_policy = NETISR_POLICY_FLOW,
144 #endif
145 };
146 
147 static int
148 sysctl_netinet6_intr_queue_maxlen(SYSCTL_HANDLER_ARGS)
149 {
150 	int error, qlimit;
151 
152 	netisr_getqlimit(&ip6_nh, &qlimit);
153 	error = sysctl_handle_int(oidp, &qlimit, 0, req);
154 	if (error || !req->newptr)
155 		return (error);
156 	if (qlimit < 1)
157 		return (EINVAL);
158 	return (netisr_setqlimit(&ip6_nh, qlimit));
159 }
160 SYSCTL_DECL(_net_inet6_ip6);
161 SYSCTL_PROC(_net_inet6_ip6, IPV6CTL_INTRQMAXLEN, intr_queue_maxlen,
162     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE,
163     0, 0, sysctl_netinet6_intr_queue_maxlen, "I",
164     "Maximum size of the IPv6 input queue");
165 
166 VNET_DEFINE_STATIC(bool, ip6_sav) = true;
167 #define	V_ip6_sav	VNET(ip6_sav)
168 SYSCTL_BOOL(_net_inet6_ip6, OID_AUTO, source_address_validation,
169     CTLFLAG_VNET | CTLFLAG_RW, &VNET_NAME(ip6_sav), true,
170     "Drop incoming packets with source address that is a local address");
171 
172 #ifdef RSS
173 static struct netisr_handler ip6_direct_nh = {
174 	.nh_name = "ip6_direct",
175 	.nh_handler = ip6_direct_input,
176 	.nh_proto = NETISR_IPV6_DIRECT,
177 	.nh_m2cpuid = rss_soft_m2cpuid_v6,
178 	.nh_policy = NETISR_POLICY_CPU,
179 	.nh_dispatch = NETISR_DISPATCH_HYBRID,
180 };
181 
182 static int
183 sysctl_netinet6_intr_direct_queue_maxlen(SYSCTL_HANDLER_ARGS)
184 {
185 	int error, qlimit;
186 
187 	netisr_getqlimit(&ip6_direct_nh, &qlimit);
188 	error = sysctl_handle_int(oidp, &qlimit, 0, req);
189 	if (error || !req->newptr)
190 		return (error);
191 	if (qlimit < 1)
192 		return (EINVAL);
193 	return (netisr_setqlimit(&ip6_direct_nh, qlimit));
194 }
195 SYSCTL_PROC(_net_inet6_ip6, IPV6CTL_INTRDQMAXLEN, intr_direct_queue_maxlen,
196     CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE,
197     0, 0, sysctl_netinet6_intr_direct_queue_maxlen, "I",
198     "Maximum size of the IPv6 direct input queue");
199 
200 #endif
201 
202 VNET_DEFINE(pfil_head_t, inet6_pfil_head);
203 
204 VNET_PCPUSTAT_DEFINE(struct ip6stat, ip6stat);
205 VNET_PCPUSTAT_SYSINIT(ip6stat);
206 #ifdef VIMAGE
207 VNET_PCPUSTAT_SYSUNINIT(ip6stat);
208 #endif /* VIMAGE */
209 
210 struct rmlock in6_ifaddr_lock;
211 RM_SYSINIT(in6_ifaddr_lock, &in6_ifaddr_lock, "in6_ifaddr_lock");
212 
213 static int ip6_hopopts_input(u_int32_t *, u_int32_t *, struct mbuf **, int *);
214 
215 /*
216  * IP6 initialization: fill in IP6 protocol switch table.
217  * All protocols not implemented in kernel go to raw IP6 protocol handler.
218  */
219 static void
220 ip6_vnet_init(void *arg __unused)
221 {
222 	struct pfil_head_args args;
223 
224 	TUNABLE_INT_FETCH("net.inet6.ip6.auto_linklocal",
225 	    &V_ip6_auto_linklocal);
226 	TUNABLE_INT_FETCH("net.inet6.ip6.accept_rtadv", &V_ip6_accept_rtadv);
227 	TUNABLE_INT_FETCH("net.inet6.ip6.no_radr", &V_ip6_no_radr);
228 
229 	CK_STAILQ_INIT(&V_in6_ifaddrhead);
230 	V_in6_ifaddrhashtbl = hashinit(IN6ADDR_NHASH, M_IFADDR,
231 	    &V_in6_ifaddrhmask);
232 
233 	/* Initialize packet filter hooks. */
234 	args.pa_version = PFIL_VERSION;
235 	args.pa_flags = PFIL_IN | PFIL_OUT;
236 	args.pa_type = PFIL_TYPE_IP6;
237 	args.pa_headname = PFIL_INET6_NAME;
238 	V_inet6_pfil_head = pfil_head_register(&args);
239 
240 	if (hhook_head_register(HHOOK_TYPE_IPSEC_IN, AF_INET6,
241 	    &V_ipsec_hhh_in[HHOOK_IPSEC_INET6],
242 	    HHOOK_WAITOK | HHOOK_HEADISINVNET) != 0)
243 		printf("%s: WARNING: unable to register input helper hook\n",
244 		    __func__);
245 	if (hhook_head_register(HHOOK_TYPE_IPSEC_OUT, AF_INET6,
246 	    &V_ipsec_hhh_out[HHOOK_IPSEC_INET6],
247 	    HHOOK_WAITOK | HHOOK_HEADISINVNET) != 0)
248 		printf("%s: WARNING: unable to register output helper hook\n",
249 		    __func__);
250 
251 	scope6_init();
252 	addrsel_policy_init();
253 	nd6_init();
254 	frag6_init();
255 
256 	V_ip6_desync_factor = arc4random() % MAX_TEMP_DESYNC_FACTOR;
257 
258 	/* Skip global initialization stuff for non-default instances. */
259 #ifdef VIMAGE
260 	netisr_register_vnet(&ip6_nh);
261 #ifdef RSS
262 	netisr_register_vnet(&ip6_direct_nh);
263 #endif
264 #endif
265 }
266 VNET_SYSINIT(ip6_vnet_init, SI_SUB_PROTO_DOMAIN, SI_ORDER_FOURTH,
267     ip6_vnet_init, NULL);
268 
269 static void
270 ip6_init(void *arg __unused)
271 {
272 	struct protosw *pr;
273 
274 	pr = pffindproto(PF_INET6, IPPROTO_RAW, SOCK_RAW);
275 	KASSERT(pr, ("%s: PF_INET6 not found", __func__));
276 
277 	/* Initialize the entire ip6_protox[] array to IPPROTO_RAW. */
278 	for (int i = 0; i < IPPROTO_MAX; i++)
279 		ip6_protox[i] = pr - inet6sw;
280 	/*
281 	 * Cycle through IP protocols and put them into the appropriate place
282 	 * in ip6_protox[].
283 	 */
284 	for (pr = inet6domain.dom_protosw;
285 	    pr < inet6domain.dom_protoswNPROTOSW; pr++)
286 		if (pr->pr_domain->dom_family == PF_INET6 &&
287 		    pr->pr_protocol && pr->pr_protocol != IPPROTO_RAW) {
288 			/* Be careful to only index valid IP protocols. */
289 			if (pr->pr_protocol < IPPROTO_MAX)
290 				ip6_protox[pr->pr_protocol] = pr - inet6sw;
291 		}
292 
293 	netisr_register(&ip6_nh);
294 #ifdef RSS
295 	netisr_register(&ip6_direct_nh);
296 #endif
297 }
298 SYSINIT(ip6_init, SI_SUB_PROTO_DOMAIN, SI_ORDER_THIRD, ip6_init, NULL);
299 
300 /*
301  * The protocol to be inserted into ip6_protox[] must be already registered
302  * in inet6sw[], either statically or through pf_proto_register().
303  */
304 int
305 ip6proto_register(short ip6proto)
306 {
307 	struct protosw *pr;
308 
309 	/* Sanity checks. */
310 	if (ip6proto <= 0 || ip6proto >= IPPROTO_MAX)
311 		return (EPROTONOSUPPORT);
312 
313 	/*
314 	 * The protocol slot must not be occupied by another protocol
315 	 * already.  An index pointing to IPPROTO_RAW is unused.
316 	 */
317 	pr = pffindproto(PF_INET6, IPPROTO_RAW, SOCK_RAW);
318 	if (pr == NULL)
319 		return (EPFNOSUPPORT);
320 	if (ip6_protox[ip6proto] != pr - inet6sw)	/* IPPROTO_RAW */
321 		return (EEXIST);
322 
323 	/*
324 	 * Find the protocol position in inet6sw[] and set the index.
325 	 */
326 	for (pr = inet6domain.dom_protosw;
327 	    pr < inet6domain.dom_protoswNPROTOSW; pr++) {
328 		if (pr->pr_domain->dom_family == PF_INET6 &&
329 		    pr->pr_protocol && pr->pr_protocol == ip6proto) {
330 			ip6_protox[pr->pr_protocol] = pr - inet6sw;
331 			return (0);
332 		}
333 	}
334 	return (EPROTONOSUPPORT);
335 }
336 
337 int
338 ip6proto_unregister(short ip6proto)
339 {
340 	struct protosw *pr;
341 
342 	/* Sanity checks. */
343 	if (ip6proto <= 0 || ip6proto >= IPPROTO_MAX)
344 		return (EPROTONOSUPPORT);
345 
346 	/* Check if the protocol was indeed registered. */
347 	pr = pffindproto(PF_INET6, IPPROTO_RAW, SOCK_RAW);
348 	if (pr == NULL)
349 		return (EPFNOSUPPORT);
350 	if (ip6_protox[ip6proto] == pr - inet6sw)	/* IPPROTO_RAW */
351 		return (ENOENT);
352 
353 	/* Reset the protocol slot to IPPROTO_RAW. */
354 	ip6_protox[ip6proto] = pr - inet6sw;
355 	return (0);
356 }
357 
358 #ifdef VIMAGE
359 static void
360 ip6_destroy(void *unused __unused)
361 {
362 	struct ifaddr *ifa, *nifa;
363 	struct ifnet *ifp;
364 	int error;
365 
366 #ifdef RSS
367 	netisr_unregister_vnet(&ip6_direct_nh);
368 #endif
369 	netisr_unregister_vnet(&ip6_nh);
370 
371 	pfil_head_unregister(V_inet6_pfil_head);
372 	error = hhook_head_deregister(V_ipsec_hhh_in[HHOOK_IPSEC_INET6]);
373 	if (error != 0) {
374 		printf("%s: WARNING: unable to deregister input helper hook "
375 		    "type HHOOK_TYPE_IPSEC_IN, id HHOOK_IPSEC_INET6: "
376 		    "error %d returned\n", __func__, error);
377 	}
378 	error = hhook_head_deregister(V_ipsec_hhh_out[HHOOK_IPSEC_INET6]);
379 	if (error != 0) {
380 		printf("%s: WARNING: unable to deregister output helper hook "
381 		    "type HHOOK_TYPE_IPSEC_OUT, id HHOOK_IPSEC_INET6: "
382 		    "error %d returned\n", __func__, error);
383 	}
384 
385 	/* Cleanup addresses. */
386 	IFNET_RLOCK();
387 	CK_STAILQ_FOREACH(ifp, &V_ifnet, if_link) {
388 		/* Cannot lock here - lock recursion. */
389 		/* IF_ADDR_LOCK(ifp); */
390 		CK_STAILQ_FOREACH_SAFE(ifa, &ifp->if_addrhead, ifa_link, nifa) {
391 			if (ifa->ifa_addr->sa_family != AF_INET6)
392 				continue;
393 			in6_purgeaddr(ifa);
394 		}
395 		/* IF_ADDR_UNLOCK(ifp); */
396 		in6_ifdetach_destroy(ifp);
397 		mld_domifdetach(ifp);
398 	}
399 	IFNET_RUNLOCK();
400 
401 	/* Make sure any routes are gone as well. */
402 	rib_flush_routes_family(AF_INET6);
403 
404 	frag6_destroy();
405 	nd6_destroy();
406 	in6_ifattach_destroy();
407 
408 	hashdestroy(V_in6_ifaddrhashtbl, M_IFADDR, V_in6_ifaddrhmask);
409 }
410 
411 VNET_SYSUNINIT(inet6, SI_SUB_PROTO_DOMAIN, SI_ORDER_THIRD, ip6_destroy, NULL);
412 #endif
413 
414 static int
415 ip6_input_hbh(struct mbuf **mp, uint32_t *plen, uint32_t *rtalert, int *off,
416     int *nxt, int *ours)
417 {
418 	struct mbuf *m;
419 	struct ip6_hdr *ip6;
420 	struct ip6_hbh *hbh;
421 
422 	if (ip6_hopopts_input(plen, rtalert, mp, off)) {
423 #if 0	/*touches NULL pointer*/
424 		in6_ifstat_inc((*mp)->m_pkthdr.rcvif, ifs6_in_discard);
425 #endif
426 		goto out;	/* m have already been freed */
427 	}
428 
429 	/* adjust pointer */
430 	m = *mp;
431 	ip6 = mtod(m, struct ip6_hdr *);
432 
433 	/*
434 	 * if the payload length field is 0 and the next header field
435 	 * indicates Hop-by-Hop Options header, then a Jumbo Payload
436 	 * option MUST be included.
437 	 */
438 	if (ip6->ip6_plen == 0 && *plen == 0) {
439 		/*
440 		 * Note that if a valid jumbo payload option is
441 		 * contained, ip6_hopopts_input() must set a valid
442 		 * (non-zero) payload length to the variable plen.
443 		 */
444 		IP6STAT_INC(ip6s_badoptions);
445 		in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_discard);
446 		in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_hdrerr);
447 		icmp6_error(m, ICMP6_PARAM_PROB,
448 			    ICMP6_PARAMPROB_HEADER,
449 			    (caddr_t)&ip6->ip6_plen - (caddr_t)ip6);
450 		goto out;
451 	}
452 	/* ip6_hopopts_input() ensures that mbuf is contiguous */
453 	hbh = (struct ip6_hbh *)(ip6 + 1);
454 	*nxt = hbh->ip6h_nxt;
455 
456 	/*
457 	 * If we are acting as a router and the packet contains a
458 	 * router alert option, see if we know the option value.
459 	 * Currently, we only support the option value for MLD, in which
460 	 * case we should pass the packet to the multicast routing
461 	 * daemon.
462 	 */
463 	if (*rtalert != ~0) {
464 		switch (*rtalert) {
465 		case IP6OPT_RTALERT_MLD:
466 			if (V_ip6_forwarding)
467 				*ours = 1;
468 			break;
469 		default:
470 			/*
471 			 * RFC2711 requires unrecognized values must be
472 			 * silently ignored.
473 			 */
474 			break;
475 		}
476 	}
477 
478 	return (0);
479 
480 out:
481 	return (1);
482 }
483 
484 #ifdef RSS
485 /*
486  * IPv6 direct input routine.
487  *
488  * This is called when reinjecting completed fragments where
489  * all of the previous checking and book-keeping has been done.
490  */
491 void
492 ip6_direct_input(struct mbuf *m)
493 {
494 	int off, nxt;
495 	int nest;
496 	struct m_tag *mtag;
497 	struct ip6_direct_ctx *ip6dc;
498 
499 	mtag = m_tag_locate(m, MTAG_ABI_IPV6, IPV6_TAG_DIRECT, NULL);
500 	KASSERT(mtag != NULL, ("Reinjected packet w/o direct ctx tag!"));
501 
502 	ip6dc = (struct ip6_direct_ctx *)(mtag + 1);
503 	nxt = ip6dc->ip6dc_nxt;
504 	off = ip6dc->ip6dc_off;
505 
506 	nest = 0;
507 
508 	m_tag_delete(m, mtag);
509 
510 	while (nxt != IPPROTO_DONE) {
511 		if (V_ip6_hdrnestlimit && (++nest > V_ip6_hdrnestlimit)) {
512 			IP6STAT_INC(ip6s_toomanyhdr);
513 			goto bad;
514 		}
515 
516 		/*
517 		 * protection against faulty packet - there should be
518 		 * more sanity checks in header chain processing.
519 		 */
520 		if (m->m_pkthdr.len < off) {
521 			IP6STAT_INC(ip6s_tooshort);
522 			in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_truncated);
523 			goto bad;
524 		}
525 
526 #if defined(IPSEC) || defined(IPSEC_SUPPORT)
527 		if (IPSEC_ENABLED(ipv6)) {
528 			if (IPSEC_INPUT(ipv6, m, off, nxt) != 0)
529 				return;
530 		}
531 #endif /* IPSEC */
532 
533 		nxt = (*inet6sw[ip6_protox[nxt]].pr_input)(&m, &off, nxt);
534 	}
535 	return;
536 bad:
537 	m_freem(m);
538 }
539 #endif
540 
541 void
542 ip6_input(struct mbuf *m)
543 {
544 	struct in6_addr odst;
545 	struct ip6_hdr *ip6;
546 	struct in6_ifaddr *ia;
547 	struct ifnet *rcvif;
548 	u_int32_t plen;
549 	u_int32_t rtalert = ~0;
550 	int off = sizeof(struct ip6_hdr), nest;
551 	int nxt, ours = 0;
552 	int srcrt = 0;
553 
554 	/*
555 	 * Drop the packet if IPv6 operation is disabled on the interface.
556 	 */
557 	rcvif = m->m_pkthdr.rcvif;
558 	if ((ND_IFINFO(rcvif)->flags & ND6_IFF_IFDISABLED))
559 		goto bad;
560 
561 #if defined(IPSEC) || defined(IPSEC_SUPPORT)
562 	/*
563 	 * should the inner packet be considered authentic?
564 	 * see comment in ah4_input().
565 	 * NB: m cannot be NULL when passed to the input routine
566 	 */
567 
568 	m->m_flags &= ~M_AUTHIPHDR;
569 	m->m_flags &= ~M_AUTHIPDGM;
570 
571 #endif /* IPSEC */
572 
573 	if (m->m_flags & M_FASTFWD_OURS) {
574 		/*
575 		 * Firewall changed destination to local.
576 		 */
577 		ip6 = mtod(m, struct ip6_hdr *);
578 		goto passin;
579 	}
580 
581 	/*
582 	 * mbuf statistics
583 	 */
584 	if (m->m_flags & M_EXT) {
585 		if (m->m_next)
586 			IP6STAT_INC(ip6s_mext2m);
587 		else
588 			IP6STAT_INC(ip6s_mext1);
589 	} else {
590 		if (m->m_next) {
591 			if (m->m_flags & M_LOOP) {
592 				IP6STAT_INC(ip6s_m2m[V_loif->if_index]);
593 			} else if (rcvif->if_index < IP6S_M2MMAX)
594 				IP6STAT_INC(ip6s_m2m[rcvif->if_index]);
595 			else
596 				IP6STAT_INC(ip6s_m2m[0]);
597 		} else
598 			IP6STAT_INC(ip6s_m1);
599 	}
600 
601 	in6_ifstat_inc(rcvif, ifs6_in_receive);
602 	IP6STAT_INC(ip6s_total);
603 
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 	if (m->m_len < sizeof(struct ip6_hdr)) {
626 		if ((m = m_pullup(m, sizeof(struct ip6_hdr))) == NULL) {
627 			IP6STAT_INC(ip6s_toosmall);
628 			in6_ifstat_inc(rcvif, ifs6_in_hdrerr);
629 			goto bad;
630 		}
631 	}
632 
633 	ip6 = mtod(m, struct ip6_hdr *);
634 	if ((ip6->ip6_vfc & IPV6_VERSION_MASK) != IPV6_VERSION) {
635 		IP6STAT_INC(ip6s_badvers);
636 		in6_ifstat_inc(rcvif, ifs6_in_hdrerr);
637 		goto bad;
638 	}
639 
640 	IP6STAT_INC(ip6s_nxthist[ip6->ip6_nxt]);
641 	IP_PROBE(receive, NULL, NULL, ip6, rcvif, NULL, ip6);
642 
643 	/*
644 	 * Check against address spoofing/corruption.
645 	 */
646 	if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_src) ||
647 	    IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_dst)) {
648 		/*
649 		 * XXX: "badscope" is not very suitable for a multicast source.
650 		 */
651 		IP6STAT_INC(ip6s_badscope);
652 		in6_ifstat_inc(rcvif, ifs6_in_addrerr);
653 		goto bad;
654 	}
655 	if (IN6_IS_ADDR_MC_INTFACELOCAL(&ip6->ip6_dst) &&
656 	    !(m->m_flags & M_LOOP)) {
657 		/*
658 		 * In this case, the packet should come from the loopback
659 		 * interface.  However, we cannot just check the if_flags,
660 		 * because ip6_mloopback() passes the "actual" interface
661 		 * as the outgoing/incoming interface.
662 		 */
663 		IP6STAT_INC(ip6s_badscope);
664 		in6_ifstat_inc(rcvif, ifs6_in_addrerr);
665 		goto bad;
666 	}
667 	if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) &&
668 	    IPV6_ADDR_MC_SCOPE(&ip6->ip6_dst) == 0) {
669 		/*
670 		 * RFC4291 2.7:
671 		 * Nodes must not originate a packet to a multicast address
672 		 * whose scop field contains the reserved value 0; if such
673 		 * a packet is received, it must be silently dropped.
674 		 */
675 		IP6STAT_INC(ip6s_badscope);
676 		in6_ifstat_inc(rcvif, ifs6_in_addrerr);
677 		goto bad;
678 	}
679 #ifdef ALTQ
680 	if (altq_input != NULL && (*altq_input)(m, AF_INET6) == 0) {
681 		/* packet is dropped by traffic conditioner */
682 		return;
683 	}
684 #endif
685 	/*
686 	 * The following check is not documented in specs.  A malicious
687 	 * party may be able to use IPv4 mapped addr to confuse tcp/udp stack
688 	 * and bypass security checks (act as if it was from 127.0.0.1 by using
689 	 * IPv6 src ::ffff:127.0.0.1).  Be cautious.
690 	 *
691 	 * We have supported IPv6-only kernels for a few years and this issue
692 	 * has not come up.  The world seems to move mostly towards not using
693 	 * v4mapped on the wire, so it makes sense for us to keep rejecting
694 	 * any such packets.
695 	 */
696 	if (IN6_IS_ADDR_V4MAPPED(&ip6->ip6_src) ||
697 	    IN6_IS_ADDR_V4MAPPED(&ip6->ip6_dst)) {
698 		IP6STAT_INC(ip6s_badscope);
699 		in6_ifstat_inc(rcvif, ifs6_in_addrerr);
700 		goto bad;
701 	}
702 #if 0
703 	/*
704 	 * Reject packets with IPv4 compatible addresses (auto tunnel).
705 	 *
706 	 * The code forbids auto tunnel relay case in RFC1933 (the check is
707 	 * stronger than RFC1933).  We may want to re-enable it if mech-xx
708 	 * is revised to forbid relaying case.
709 	 */
710 	if (IN6_IS_ADDR_V4COMPAT(&ip6->ip6_src) ||
711 	    IN6_IS_ADDR_V4COMPAT(&ip6->ip6_dst)) {
712 		IP6STAT_INC(ip6s_badscope);
713 		in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_addrerr);
714 		goto bad;
715 	}
716 #endif
717 	/*
718 	 * Try to forward the packet, but if we fail continue.
719 	 * ip6_tryforward() does not generate redirects, so fall
720 	 * through to normal processing if redirects are required.
721 	 * ip6_tryforward() does inbound and outbound packet firewall
722 	 * processing. If firewall has decided that destination becomes
723 	 * our local address, it sets M_FASTFWD_OURS flag. In this
724 	 * case skip another inbound firewall processing and update
725 	 * ip6 pointer.
726 	 */
727 	if (V_ip6_forwarding != 0 && V_ip6_sendredirects == 0
728 #if defined(IPSEC) || defined(IPSEC_SUPPORT)
729 	    && (!IPSEC_ENABLED(ipv6) ||
730 	    IPSEC_CAPS(ipv6, m, IPSEC_CAP_OPERABLE) == 0)
731 #endif
732 	    ) {
733 		if ((m = ip6_tryforward(m)) == NULL)
734 			return;
735 		if (m->m_flags & M_FASTFWD_OURS) {
736 			ip6 = mtod(m, struct ip6_hdr *);
737 			goto passin;
738 		}
739 	}
740 #if defined(IPSEC) || defined(IPSEC_SUPPORT)
741 	/*
742 	 * Bypass packet filtering for packets previously handled by IPsec.
743 	 */
744 	if (IPSEC_ENABLED(ipv6) &&
745 	    IPSEC_CAPS(ipv6, m, IPSEC_CAP_BYPASS_FILTER) != 0)
746 			goto passin;
747 #endif
748 	/*
749 	 * Run through list of hooks for input packets.
750 	 *
751 	 * NB: Beware of the destination address changing
752 	 *     (e.g. by NAT rewriting).  When this happens,
753 	 *     tell ip6_forward to do the right thing.
754 	 */
755 
756 	/* Jump over all PFIL processing if hooks are not active. */
757 	if (!PFIL_HOOKED_IN(V_inet6_pfil_head))
758 		goto passin;
759 
760 	odst = ip6->ip6_dst;
761 	if (pfil_run_hooks(V_inet6_pfil_head, &m, m->m_pkthdr.rcvif, PFIL_IN,
762 	    NULL) != PFIL_PASS)
763 		return;
764 	ip6 = mtod(m, struct ip6_hdr *);
765 	srcrt = !IN6_ARE_ADDR_EQUAL(&odst, &ip6->ip6_dst);
766 	if ((m->m_flags & (M_IP6_NEXTHOP | M_FASTFWD_OURS)) == M_IP6_NEXTHOP &&
767 	    m_tag_find(m, PACKET_TAG_IPFORWARD, NULL) != NULL) {
768 		/*
769 		 * Directly ship the packet on.  This allows forwarding
770 		 * packets originally destined to us to some other directly
771 		 * connected host.
772 		 */
773 		ip6_forward(m, 1);
774 		return;
775 	}
776 
777 passin:
778 	/*
779 	 * Disambiguate address scope zones (if there is ambiguity).
780 	 * We first make sure that the original source or destination address
781 	 * is not in our internal form for scoped addresses.  Such addresses
782 	 * are not necessarily invalid spec-wise, but we cannot accept them due
783 	 * to the usage conflict.
784 	 * in6_setscope() then also checks and rejects the cases where src or
785 	 * dst are the loopback address and the receiving interface
786 	 * is not loopback.
787 	 */
788 	if (in6_clearscope(&ip6->ip6_src) || in6_clearscope(&ip6->ip6_dst)) {
789 		IP6STAT_INC(ip6s_badscope); /* XXX */
790 		goto bad;
791 	}
792 	if (in6_setscope(&ip6->ip6_src, rcvif, NULL) ||
793 	    in6_setscope(&ip6->ip6_dst, rcvif, NULL)) {
794 		IP6STAT_INC(ip6s_badscope);
795 		goto bad;
796 	}
797 	if (m->m_flags & M_FASTFWD_OURS) {
798 		m->m_flags &= ~M_FASTFWD_OURS;
799 		ours = 1;
800 		goto hbhcheck;
801 	}
802 	/*
803 	 * Multicast check. Assume packet is for us to avoid
804 	 * prematurely taking locks.
805 	 */
806 	if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) {
807 		ours = 1;
808 		in6_ifstat_inc(rcvif, ifs6_in_mcast);
809 		goto hbhcheck;
810 	}
811 	/*
812 	 * Unicast check
813 	 * XXX: For now we keep link-local IPv6 addresses with embedded
814 	 *      scope zone id, therefore we use zero zoneid here.
815 	 */
816 	ia = in6ifa_ifwithaddr(&ip6->ip6_dst, 0 /* XXX */, false);
817 	if (ia != NULL) {
818 		if (ia->ia6_flags & IN6_IFF_NOTREADY) {
819 			char ip6bufs[INET6_ADDRSTRLEN];
820 			char ip6bufd[INET6_ADDRSTRLEN];
821 			/* address is not ready, so discard the packet. */
822 			nd6log((LOG_INFO,
823 			    "ip6_input: packet to an unready address %s->%s\n",
824 			    ip6_sprintf(ip6bufs, &ip6->ip6_src),
825 			    ip6_sprintf(ip6bufd, &ip6->ip6_dst)));
826 			goto bad;
827 		}
828 		if (V_ip6_sav && !(rcvif->if_flags & IFF_LOOPBACK) &&
829 		    __predict_false(in6_localip_fib(&ip6->ip6_src,
830 			    rcvif->if_fib))) {
831 			IP6STAT_INC(ip6s_badscope); /* XXX */
832 			goto bad;
833 		}
834 		/* Count the packet in the ip address stats */
835 		counter_u64_add(ia->ia_ifa.ifa_ipackets, 1);
836 		counter_u64_add(ia->ia_ifa.ifa_ibytes, m->m_pkthdr.len);
837 		ours = 1;
838 		goto hbhcheck;
839 	}
840 
841 	/*
842 	 * Now there is no reason to process the packet if it's not our own
843 	 * and we're not a router.
844 	 */
845 	if (!V_ip6_forwarding) {
846 		IP6STAT_INC(ip6s_cantforward);
847 		goto bad;
848 	}
849 
850   hbhcheck:
851 	/*
852 	 * Process Hop-by-Hop options header if it's contained.
853 	 * m may be modified in ip6_hopopts_input().
854 	 * If a JumboPayload option is included, plen will also be modified.
855 	 */
856 	plen = (u_int32_t)ntohs(ip6->ip6_plen);
857 	if (ip6->ip6_nxt == IPPROTO_HOPOPTS) {
858 		if (ip6_input_hbh(&m, &plen, &rtalert, &off, &nxt, &ours) != 0)
859 			return;
860 	} else
861 		nxt = ip6->ip6_nxt;
862 
863 	/*
864 	 * Use mbuf flags to propagate Router Alert option to
865 	 * ICMPv6 layer, as hop-by-hop options have been stripped.
866 	 */
867 	if (rtalert != ~0)
868 		m->m_flags |= M_RTALERT_MLD;
869 
870 	/*
871 	 * Check that the amount of data in the buffers
872 	 * is as at least much as the IPv6 header would have us expect.
873 	 * Trim mbufs if longer than we expect.
874 	 * Drop packet if shorter than we expect.
875 	 */
876 	if (m->m_pkthdr.len - sizeof(struct ip6_hdr) < plen) {
877 		IP6STAT_INC(ip6s_tooshort);
878 		in6_ifstat_inc(rcvif, ifs6_in_truncated);
879 		goto bad;
880 	}
881 	if (m->m_pkthdr.len > sizeof(struct ip6_hdr) + plen) {
882 		if (m->m_len == m->m_pkthdr.len) {
883 			m->m_len = sizeof(struct ip6_hdr) + plen;
884 			m->m_pkthdr.len = sizeof(struct ip6_hdr) + plen;
885 		} else
886 			m_adj(m, sizeof(struct ip6_hdr) + plen - m->m_pkthdr.len);
887 	}
888 
889 	/*
890 	 * Forward if desirable.
891 	 */
892 	if (V_ip6_mrouter &&
893 	    IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) {
894 		/*
895 		 * If we are acting as a multicast router, all
896 		 * incoming multicast packets are passed to the
897 		 * kernel-level multicast forwarding function.
898 		 * The packet is returned (relatively) intact; if
899 		 * ip6_mforward() returns a non-zero value, the packet
900 		 * must be discarded, else it may be accepted below.
901 		 *
902 		 * XXX TODO: Check hlim and multicast scope here to avoid
903 		 * unnecessarily calling into ip6_mforward().
904 		 */
905 		if (ip6_mforward && ip6_mforward(ip6, rcvif, m)) {
906 			IP6STAT_INC(ip6s_cantforward);
907 			goto bad;
908 		}
909 	} else if (!ours) {
910 		ip6_forward(m, srcrt);
911 		return;
912 	}
913 
914 	/*
915 	 * Tell launch routine the next header
916 	 */
917 	IP6STAT_INC(ip6s_delivered);
918 	in6_ifstat_inc(rcvif, ifs6_in_deliver);
919 	nest = 0;
920 
921 	while (nxt != IPPROTO_DONE) {
922 		if (V_ip6_hdrnestlimit && (++nest > V_ip6_hdrnestlimit)) {
923 			IP6STAT_INC(ip6s_toomanyhdr);
924 			goto bad;
925 		}
926 
927 		/*
928 		 * protection against faulty packet - there should be
929 		 * more sanity checks in header chain processing.
930 		 */
931 		if (m->m_pkthdr.len < off) {
932 			IP6STAT_INC(ip6s_tooshort);
933 			in6_ifstat_inc(rcvif, ifs6_in_truncated);
934 			goto bad;
935 		}
936 
937 #if defined(IPSEC) || defined(IPSEC_SUPPORT)
938 		if (IPSEC_ENABLED(ipv6)) {
939 			if (IPSEC_INPUT(ipv6, m, off, nxt) != 0)
940 				return;
941 		}
942 #endif /* IPSEC */
943 
944 		nxt = (*inet6sw[ip6_protox[nxt]].pr_input)(&m, &off, nxt);
945 	}
946 	return;
947 bad:
948 	in6_ifstat_inc(rcvif, ifs6_in_discard);
949 	if (m != NULL)
950 		m_freem(m);
951 }
952 
953 /*
954  * Hop-by-Hop options header processing. If a valid jumbo payload option is
955  * included, the real payload length will be stored in plenp.
956  *
957  * rtalertp - XXX: should be stored more smart way
958  */
959 static int
960 ip6_hopopts_input(u_int32_t *plenp, u_int32_t *rtalertp,
961     struct mbuf **mp, int *offp)
962 {
963 	struct mbuf *m = *mp;
964 	int off = *offp, hbhlen;
965 	struct ip6_hbh *hbh;
966 
967 	/* validation of the length of the header */
968 	if (m->m_len < off + sizeof(*hbh)) {
969 		m = m_pullup(m, off + sizeof(*hbh));
970 		if (m == NULL) {
971 			IP6STAT_INC(ip6s_exthdrtoolong);
972 			*mp = NULL;
973 			return (-1);
974 		}
975 	}
976 	hbh = (struct ip6_hbh *)(mtod(m, caddr_t) + off);
977 	hbhlen = (hbh->ip6h_len + 1) << 3;
978 
979 	if (m->m_len < off + hbhlen) {
980 		m = m_pullup(m, off + hbhlen);
981 		if (m == NULL) {
982 			IP6STAT_INC(ip6s_exthdrtoolong);
983 			*mp = NULL;
984 			return (-1);
985 		}
986 	}
987 	hbh = (struct ip6_hbh *)(mtod(m, caddr_t) + off);
988 	off += hbhlen;
989 	hbhlen -= sizeof(struct ip6_hbh);
990 	if (ip6_process_hopopts(m, (u_int8_t *)hbh + sizeof(struct ip6_hbh),
991 				hbhlen, rtalertp, plenp) < 0) {
992 		*mp = NULL;
993 		return (-1);
994 	}
995 
996 	*offp = off;
997 	*mp = m;
998 	return (0);
999 }
1000 
1001 /*
1002  * Search header for all Hop-by-hop options and process each option.
1003  * This function is separate from ip6_hopopts_input() in order to
1004  * handle a case where the sending node itself process its hop-by-hop
1005  * options header. In such a case, the function is called from ip6_output().
1006  *
1007  * The function assumes that hbh header is located right after the IPv6 header
1008  * (RFC2460 p7), opthead is pointer into data content in m, and opthead to
1009  * opthead + hbhlen is located in contiguous memory region.
1010  */
1011 int
1012 ip6_process_hopopts(struct mbuf *m, u_int8_t *opthead, int hbhlen,
1013     u_int32_t *rtalertp, u_int32_t *plenp)
1014 {
1015 	struct ip6_hdr *ip6;
1016 	int optlen = 0;
1017 	u_int8_t *opt = opthead;
1018 	u_int16_t rtalert_val;
1019 	u_int32_t jumboplen;
1020 	const int erroff = sizeof(struct ip6_hdr) + sizeof(struct ip6_hbh);
1021 
1022 	for (; hbhlen > 0; hbhlen -= optlen, opt += optlen) {
1023 		switch (*opt) {
1024 		case IP6OPT_PAD1:
1025 			optlen = 1;
1026 			break;
1027 		case IP6OPT_PADN:
1028 			if (hbhlen < IP6OPT_MINLEN) {
1029 				IP6STAT_INC(ip6s_toosmall);
1030 				goto bad;
1031 			}
1032 			optlen = *(opt + 1) + 2;
1033 			break;
1034 		case IP6OPT_ROUTER_ALERT:
1035 			/* XXX may need check for alignment */
1036 			if (hbhlen < IP6OPT_RTALERT_LEN) {
1037 				IP6STAT_INC(ip6s_toosmall);
1038 				goto bad;
1039 			}
1040 			if (*(opt + 1) != IP6OPT_RTALERT_LEN - 2) {
1041 				/* XXX stat */
1042 				icmp6_error(m, ICMP6_PARAM_PROB,
1043 				    ICMP6_PARAMPROB_HEADER,
1044 				    erroff + opt + 1 - opthead);
1045 				return (-1);
1046 			}
1047 			optlen = IP6OPT_RTALERT_LEN;
1048 			bcopy((caddr_t)(opt + 2), (caddr_t)&rtalert_val, 2);
1049 			*rtalertp = ntohs(rtalert_val);
1050 			break;
1051 		case IP6OPT_JUMBO:
1052 			/* XXX may need check for alignment */
1053 			if (hbhlen < IP6OPT_JUMBO_LEN) {
1054 				IP6STAT_INC(ip6s_toosmall);
1055 				goto bad;
1056 			}
1057 			if (*(opt + 1) != IP6OPT_JUMBO_LEN - 2) {
1058 				/* XXX stat */
1059 				icmp6_error(m, ICMP6_PARAM_PROB,
1060 				    ICMP6_PARAMPROB_HEADER,
1061 				    erroff + opt + 1 - opthead);
1062 				return (-1);
1063 			}
1064 			optlen = IP6OPT_JUMBO_LEN;
1065 
1066 			/*
1067 			 * IPv6 packets that have non 0 payload length
1068 			 * must not contain a jumbo payload option.
1069 			 */
1070 			ip6 = mtod(m, struct ip6_hdr *);
1071 			if (ip6->ip6_plen) {
1072 				IP6STAT_INC(ip6s_badoptions);
1073 				icmp6_error(m, ICMP6_PARAM_PROB,
1074 				    ICMP6_PARAMPROB_HEADER,
1075 				    erroff + opt - opthead);
1076 				return (-1);
1077 			}
1078 
1079 			/*
1080 			 * We may see jumbolen in unaligned location, so
1081 			 * we'd need to perform bcopy().
1082 			 */
1083 			bcopy(opt + 2, &jumboplen, sizeof(jumboplen));
1084 			jumboplen = (u_int32_t)htonl(jumboplen);
1085 
1086 #if 1
1087 			/*
1088 			 * if there are multiple jumbo payload options,
1089 			 * *plenp will be non-zero and the packet will be
1090 			 * rejected.
1091 			 * the behavior may need some debate in ipngwg -
1092 			 * multiple options does not make sense, however,
1093 			 * there's no explicit mention in specification.
1094 			 */
1095 			if (*plenp != 0) {
1096 				IP6STAT_INC(ip6s_badoptions);
1097 				icmp6_error(m, ICMP6_PARAM_PROB,
1098 				    ICMP6_PARAMPROB_HEADER,
1099 				    erroff + opt + 2 - opthead);
1100 				return (-1);
1101 			}
1102 #endif
1103 
1104 			/*
1105 			 * jumbo payload length must be larger than 65535.
1106 			 */
1107 			if (jumboplen <= IPV6_MAXPACKET) {
1108 				IP6STAT_INC(ip6s_badoptions);
1109 				icmp6_error(m, ICMP6_PARAM_PROB,
1110 				    ICMP6_PARAMPROB_HEADER,
1111 				    erroff + opt + 2 - opthead);
1112 				return (-1);
1113 			}
1114 			*plenp = jumboplen;
1115 
1116 			break;
1117 		default:		/* unknown option */
1118 			if (hbhlen < IP6OPT_MINLEN) {
1119 				IP6STAT_INC(ip6s_toosmall);
1120 				goto bad;
1121 			}
1122 			optlen = ip6_unknown_opt(opt, m,
1123 			    erroff + opt - opthead);
1124 			if (optlen == -1)
1125 				return (-1);
1126 			optlen += 2;
1127 			break;
1128 		}
1129 	}
1130 
1131 	return (0);
1132 
1133   bad:
1134 	m_freem(m);
1135 	return (-1);
1136 }
1137 
1138 /*
1139  * Unknown option processing.
1140  * The third argument `off' is the offset from the IPv6 header to the option,
1141  * which is necessary if the IPv6 header the and option header and IPv6 header
1142  * is not contiguous in order to return an ICMPv6 error.
1143  */
1144 int
1145 ip6_unknown_opt(u_int8_t *optp, struct mbuf *m, int off)
1146 {
1147 	struct ip6_hdr *ip6;
1148 
1149 	switch (IP6OPT_TYPE(*optp)) {
1150 	case IP6OPT_TYPE_SKIP: /* ignore the option */
1151 		return ((int)*(optp + 1));
1152 	case IP6OPT_TYPE_DISCARD:	/* silently discard */
1153 		m_freem(m);
1154 		return (-1);
1155 	case IP6OPT_TYPE_FORCEICMP: /* send ICMP even if multicasted */
1156 		IP6STAT_INC(ip6s_badoptions);
1157 		icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_OPTION, off);
1158 		return (-1);
1159 	case IP6OPT_TYPE_ICMP: /* send ICMP if not multicasted */
1160 		IP6STAT_INC(ip6s_badoptions);
1161 		ip6 = mtod(m, struct ip6_hdr *);
1162 		if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) ||
1163 		    (m->m_flags & (M_BCAST|M_MCAST)))
1164 			m_freem(m);
1165 		else
1166 			icmp6_error(m, ICMP6_PARAM_PROB,
1167 				    ICMP6_PARAMPROB_OPTION, off);
1168 		return (-1);
1169 	}
1170 
1171 	m_freem(m);		/* XXX: NOTREACHED */
1172 	return (-1);
1173 }
1174 
1175 /*
1176  * Create the "control" list for this pcb.
1177  * These functions will not modify mbuf chain at all.
1178  *
1179  * The routine will be called from upper layer handlers like tcp6_input().
1180  * Thus the routine assumes that the caller (tcp6_input) have already
1181  * called m_pullup() and all the extension headers are located in the
1182  * very first mbuf on the mbuf chain.
1183  *
1184  * ip6_savecontrol_v4 will handle those options that are possible to be
1185  * set on a v4-mapped socket.
1186  * ip6_savecontrol will directly call ip6_savecontrol_v4 to handle those
1187  * options and handle the v6-only ones itself.
1188  */
1189 struct mbuf **
1190 ip6_savecontrol_v4(struct inpcb *inp, struct mbuf *m, struct mbuf **mp,
1191     int *v4only)
1192 {
1193 	struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
1194 
1195 #ifdef SO_TIMESTAMP
1196 	if ((inp->inp_socket->so_options & SO_TIMESTAMP) != 0) {
1197 		union {
1198 			struct timeval tv;
1199 			struct bintime bt;
1200 			struct timespec ts;
1201 		} t;
1202 		struct bintime boottimebin, bt1;
1203 		struct timespec ts1;
1204 		bool stamped;
1205 
1206 		stamped = false;
1207 		switch (inp->inp_socket->so_ts_clock) {
1208 		case SO_TS_REALTIME_MICRO:
1209 			if ((m->m_flags & (M_PKTHDR | M_TSTMP)) == (M_PKTHDR |
1210 			    M_TSTMP)) {
1211 				mbuf_tstmp2timespec(m, &ts1);
1212 				timespec2bintime(&ts1, &bt1);
1213 				getboottimebin(&boottimebin);
1214 				bintime_add(&bt1, &boottimebin);
1215 				bintime2timeval(&bt1, &t.tv);
1216 			} else {
1217 				microtime(&t.tv);
1218 			}
1219 			*mp = sbcreatecontrol((caddr_t) &t.tv, sizeof(t.tv),
1220 			    SCM_TIMESTAMP, SOL_SOCKET);
1221 			if (*mp != NULL) {
1222 				mp = &(*mp)->m_next;
1223 				stamped = true;
1224 			}
1225 			break;
1226 
1227 		case SO_TS_BINTIME:
1228 			if ((m->m_flags & (M_PKTHDR | M_TSTMP)) == (M_PKTHDR |
1229 			    M_TSTMP)) {
1230 				mbuf_tstmp2timespec(m, &ts1);
1231 				timespec2bintime(&ts1, &t.bt);
1232 				getboottimebin(&boottimebin);
1233 				bintime_add(&t.bt, &boottimebin);
1234 			} else {
1235 				bintime(&t.bt);
1236 			}
1237 			*mp = sbcreatecontrol((caddr_t)&t.bt, sizeof(t.bt),
1238 			    SCM_BINTIME, SOL_SOCKET);
1239 			if (*mp != NULL) {
1240 				mp = &(*mp)->m_next;
1241 				stamped = true;
1242 			}
1243 			break;
1244 
1245 		case SO_TS_REALTIME:
1246 			if ((m->m_flags & (M_PKTHDR | M_TSTMP)) == (M_PKTHDR |
1247 			    M_TSTMP)) {
1248 				mbuf_tstmp2timespec(m, &t.ts);
1249 				getboottimebin(&boottimebin);
1250 				bintime2timespec(&boottimebin, &ts1);
1251 				timespecadd(&t.ts, &ts1, &t.ts);
1252 			} else {
1253 				nanotime(&t.ts);
1254 			}
1255 			*mp = sbcreatecontrol((caddr_t)&t.ts, sizeof(t.ts),
1256 			    SCM_REALTIME, SOL_SOCKET);
1257 			if (*mp != NULL) {
1258 				mp = &(*mp)->m_next;
1259 				stamped = true;
1260 			}
1261 			break;
1262 
1263 		case SO_TS_MONOTONIC:
1264 			if ((m->m_flags & (M_PKTHDR | M_TSTMP)) == (M_PKTHDR |
1265 			    M_TSTMP))
1266 				mbuf_tstmp2timespec(m, &t.ts);
1267 			else
1268 				nanouptime(&t.ts);
1269 			*mp = sbcreatecontrol((caddr_t)&t.ts, sizeof(t.ts),
1270 			    SCM_MONOTONIC, SOL_SOCKET);
1271 			if (*mp != NULL) {
1272 				mp = &(*mp)->m_next;
1273 				stamped = true;
1274 			}
1275 			break;
1276 
1277 		default:
1278 			panic("unknown (corrupted) so_ts_clock");
1279 		}
1280 		if (stamped && (m->m_flags & (M_PKTHDR | M_TSTMP)) ==
1281 		    (M_PKTHDR | M_TSTMP)) {
1282 			struct sock_timestamp_info sti;
1283 
1284 			bzero(&sti, sizeof(sti));
1285 			sti.st_info_flags = ST_INFO_HW;
1286 			if ((m->m_flags & M_TSTMP_HPREC) != 0)
1287 				sti.st_info_flags |= ST_INFO_HW_HPREC;
1288 			*mp = sbcreatecontrol((caddr_t)&sti, sizeof(sti),
1289 			    SCM_TIME_INFO, SOL_SOCKET);
1290 			if (*mp != NULL)
1291 				mp = &(*mp)->m_next;
1292 		}
1293 	}
1294 #endif
1295 
1296 #define IS2292(inp, x, y)	(((inp)->inp_flags & IN6P_RFC2292) ? (x) : (y))
1297 	/* RFC 2292 sec. 5 */
1298 	if ((inp->inp_flags & IN6P_PKTINFO) != 0) {
1299 		struct in6_pktinfo pi6;
1300 
1301 		if ((ip6->ip6_vfc & IPV6_VERSION_MASK) != IPV6_VERSION) {
1302 #ifdef INET
1303 			struct ip *ip;
1304 
1305 			ip = mtod(m, struct ip *);
1306 			pi6.ipi6_addr.s6_addr32[0] = 0;
1307 			pi6.ipi6_addr.s6_addr32[1] = 0;
1308 			pi6.ipi6_addr.s6_addr32[2] = IPV6_ADDR_INT32_SMP;
1309 			pi6.ipi6_addr.s6_addr32[3] = ip->ip_dst.s_addr;
1310 #else
1311 			/* We won't hit this code */
1312 			bzero(&pi6.ipi6_addr, sizeof(struct in6_addr));
1313 #endif
1314 		} else {
1315 			bcopy(&ip6->ip6_dst, &pi6.ipi6_addr, sizeof(struct in6_addr));
1316 			in6_clearscope(&pi6.ipi6_addr);	/* XXX */
1317 		}
1318 		pi6.ipi6_ifindex =
1319 		    (m && m->m_pkthdr.rcvif) ? m->m_pkthdr.rcvif->if_index : 0;
1320 
1321 		*mp = sbcreatecontrol((caddr_t) &pi6,
1322 		    sizeof(struct in6_pktinfo),
1323 		    IS2292(inp, IPV6_2292PKTINFO, IPV6_PKTINFO), IPPROTO_IPV6);
1324 		if (*mp)
1325 			mp = &(*mp)->m_next;
1326 	}
1327 
1328 	if ((inp->inp_flags & IN6P_HOPLIMIT) != 0) {
1329 		int hlim;
1330 
1331 		if ((ip6->ip6_vfc & IPV6_VERSION_MASK) != IPV6_VERSION) {
1332 #ifdef INET
1333 			struct ip *ip;
1334 
1335 			ip = mtod(m, struct ip *);
1336 			hlim = ip->ip_ttl;
1337 #else
1338 			/* We won't hit this code */
1339 			hlim = 0;
1340 #endif
1341 		} else {
1342 			hlim = ip6->ip6_hlim & 0xff;
1343 		}
1344 		*mp = sbcreatecontrol((caddr_t) &hlim, sizeof(int),
1345 		    IS2292(inp, IPV6_2292HOPLIMIT, IPV6_HOPLIMIT),
1346 		    IPPROTO_IPV6);
1347 		if (*mp)
1348 			mp = &(*mp)->m_next;
1349 	}
1350 
1351 	if ((inp->inp_flags & IN6P_TCLASS) != 0) {
1352 		int tclass;
1353 
1354 		if ((ip6->ip6_vfc & IPV6_VERSION_MASK) != IPV6_VERSION) {
1355 #ifdef INET
1356 			struct ip *ip;
1357 
1358 			ip = mtod(m, struct ip *);
1359 			tclass = ip->ip_tos;
1360 #else
1361 			/* We won't hit this code */
1362 			tclass = 0;
1363 #endif
1364 		} else {
1365 			u_int32_t flowinfo;
1366 
1367 			flowinfo = (u_int32_t)ntohl(ip6->ip6_flow & IPV6_FLOWINFO_MASK);
1368 			flowinfo >>= 20;
1369 			tclass = flowinfo & 0xff;
1370 		}
1371 		*mp = sbcreatecontrol((caddr_t) &tclass, sizeof(int),
1372 		    IPV6_TCLASS, IPPROTO_IPV6);
1373 		if (*mp)
1374 			mp = &(*mp)->m_next;
1375 	}
1376 
1377 	if (v4only != NULL) {
1378 		if ((ip6->ip6_vfc & IPV6_VERSION_MASK) != IPV6_VERSION) {
1379 			*v4only = 1;
1380 		} else {
1381 			*v4only = 0;
1382 		}
1383 	}
1384 
1385 	return (mp);
1386 }
1387 
1388 void
1389 ip6_savecontrol(struct inpcb *inp, struct mbuf *m, struct mbuf **mp)
1390 {
1391 	struct ip6_hdr *ip6;
1392 	int v4only = 0;
1393 
1394 	mp = ip6_savecontrol_v4(inp, m, mp, &v4only);
1395 	if (v4only)
1396 		return;
1397 
1398 	ip6 = mtod(m, struct ip6_hdr *);
1399 	/*
1400 	 * IPV6_HOPOPTS socket option.  Recall that we required super-user
1401 	 * privilege for the option (see ip6_ctloutput), but it might be too
1402 	 * strict, since there might be some hop-by-hop options which can be
1403 	 * returned to normal user.
1404 	 * See also RFC 2292 section 6 (or RFC 3542 section 8).
1405 	 */
1406 	if ((inp->inp_flags & IN6P_HOPOPTS) != 0) {
1407 		/*
1408 		 * Check if a hop-by-hop options header is contatined in the
1409 		 * received packet, and if so, store the options as ancillary
1410 		 * data. Note that a hop-by-hop options header must be
1411 		 * just after the IPv6 header, which is assured through the
1412 		 * IPv6 input processing.
1413 		 */
1414 		if (ip6->ip6_nxt == IPPROTO_HOPOPTS) {
1415 			struct ip6_hbh *hbh;
1416 			int hbhlen;
1417 
1418 			hbh = (struct ip6_hbh *)(ip6 + 1);
1419 			hbhlen = (hbh->ip6h_len + 1) << 3;
1420 
1421 			/*
1422 			 * XXX: We copy the whole header even if a
1423 			 * jumbo payload option is included, the option which
1424 			 * is to be removed before returning according to
1425 			 * RFC2292.
1426 			 * Note: this constraint is removed in RFC3542
1427 			 */
1428 			*mp = sbcreatecontrol((caddr_t)hbh, hbhlen,
1429 			    IS2292(inp, IPV6_2292HOPOPTS, IPV6_HOPOPTS),
1430 			    IPPROTO_IPV6);
1431 			if (*mp)
1432 				mp = &(*mp)->m_next;
1433 		}
1434 	}
1435 
1436 	if ((inp->inp_flags & (IN6P_RTHDR | IN6P_DSTOPTS)) != 0) {
1437 		int nxt = ip6->ip6_nxt, off = sizeof(struct ip6_hdr);
1438 
1439 		/*
1440 		 * Search for destination options headers or routing
1441 		 * header(s) through the header chain, and stores each
1442 		 * header as ancillary data.
1443 		 * Note that the order of the headers remains in
1444 		 * the chain of ancillary data.
1445 		 */
1446 		while (1) {	/* is explicit loop prevention necessary? */
1447 			struct ip6_ext *ip6e = NULL;
1448 			int elen;
1449 
1450 			/*
1451 			 * if it is not an extension header, don't try to
1452 			 * pull it from the chain.
1453 			 */
1454 			switch (nxt) {
1455 			case IPPROTO_DSTOPTS:
1456 			case IPPROTO_ROUTING:
1457 			case IPPROTO_HOPOPTS:
1458 			case IPPROTO_AH: /* is it possible? */
1459 				break;
1460 			default:
1461 				goto loopend;
1462 			}
1463 
1464 			if (off + sizeof(*ip6e) > m->m_len)
1465 				goto loopend;
1466 			ip6e = (struct ip6_ext *)(mtod(m, caddr_t) + off);
1467 			if (nxt == IPPROTO_AH)
1468 				elen = (ip6e->ip6e_len + 2) << 2;
1469 			else
1470 				elen = (ip6e->ip6e_len + 1) << 3;
1471 			if (off + elen > m->m_len)
1472 				goto loopend;
1473 
1474 			switch (nxt) {
1475 			case IPPROTO_DSTOPTS:
1476 				if (!(inp->inp_flags & IN6P_DSTOPTS))
1477 					break;
1478 
1479 				*mp = sbcreatecontrol((caddr_t)ip6e, elen,
1480 				    IS2292(inp,
1481 					IPV6_2292DSTOPTS, IPV6_DSTOPTS),
1482 				    IPPROTO_IPV6);
1483 				if (*mp)
1484 					mp = &(*mp)->m_next;
1485 				break;
1486 			case IPPROTO_ROUTING:
1487 				if (!(inp->inp_flags & IN6P_RTHDR))
1488 					break;
1489 
1490 				*mp = sbcreatecontrol((caddr_t)ip6e, elen,
1491 				    IS2292(inp, IPV6_2292RTHDR, IPV6_RTHDR),
1492 				    IPPROTO_IPV6);
1493 				if (*mp)
1494 					mp = &(*mp)->m_next;
1495 				break;
1496 			case IPPROTO_HOPOPTS:
1497 			case IPPROTO_AH: /* is it possible? */
1498 				break;
1499 
1500 			default:
1501 				/*
1502 				 * other cases have been filtered in the above.
1503 				 * none will visit this case.  here we supply
1504 				 * the code just in case (nxt overwritten or
1505 				 * other cases).
1506 				 */
1507 				goto loopend;
1508 			}
1509 
1510 			/* proceed with the next header. */
1511 			off += elen;
1512 			nxt = ip6e->ip6e_nxt;
1513 			ip6e = NULL;
1514 		}
1515 	  loopend:
1516 		;
1517 	}
1518 
1519 	if (inp->inp_flags2 & INP_RECVFLOWID) {
1520 		uint32_t flowid, flow_type;
1521 
1522 		flowid = m->m_pkthdr.flowid;
1523 		flow_type = M_HASHTYPE_GET(m);
1524 
1525 		/*
1526 		 * XXX should handle the failure of one or the
1527 		 * other - don't populate both?
1528 		 */
1529 		*mp = sbcreatecontrol((caddr_t) &flowid,
1530 		    sizeof(uint32_t), IPV6_FLOWID, IPPROTO_IPV6);
1531 		if (*mp)
1532 			mp = &(*mp)->m_next;
1533 		*mp = sbcreatecontrol((caddr_t) &flow_type,
1534 		    sizeof(uint32_t), IPV6_FLOWTYPE, IPPROTO_IPV6);
1535 		if (*mp)
1536 			mp = &(*mp)->m_next;
1537 	}
1538 
1539 #ifdef	RSS
1540 	if (inp->inp_flags2 & INP_RECVRSSBUCKETID) {
1541 		uint32_t flowid, flow_type;
1542 		uint32_t rss_bucketid;
1543 
1544 		flowid = m->m_pkthdr.flowid;
1545 		flow_type = M_HASHTYPE_GET(m);
1546 
1547 		if (rss_hash2bucket(flowid, flow_type, &rss_bucketid) == 0) {
1548 			*mp = sbcreatecontrol((caddr_t) &rss_bucketid,
1549 			   sizeof(uint32_t), IPV6_RSSBUCKETID, IPPROTO_IPV6);
1550 			if (*mp)
1551 				mp = &(*mp)->m_next;
1552 		}
1553 	}
1554 #endif
1555 
1556 }
1557 #undef IS2292
1558 
1559 void
1560 ip6_notify_pmtu(struct inpcb *inp, struct sockaddr_in6 *dst, u_int32_t mtu)
1561 {
1562 	struct socket *so;
1563 	struct mbuf *m_mtu;
1564 	struct ip6_mtuinfo mtuctl;
1565 
1566 	KASSERT(inp != NULL, ("%s: inp == NULL", __func__));
1567 	/*
1568 	 * Notify the error by sending IPV6_PATHMTU ancillary data if
1569 	 * application wanted to know the MTU value.
1570 	 * NOTE: we notify disconnected sockets, because some udp
1571 	 * applications keep sending sockets disconnected.
1572 	 * NOTE: our implementation doesn't notify connected sockets that has
1573 	 * foreign address that is different than given destination addresses
1574 	 * (this is permitted by RFC 3542).
1575 	 */
1576 	if ((inp->inp_flags & IN6P_MTU) == 0 || (
1577 	    !IN6_IS_ADDR_UNSPECIFIED(&inp->in6p_faddr) &&
1578 	    !IN6_ARE_ADDR_EQUAL(&inp->in6p_faddr, &dst->sin6_addr)))
1579 		return;
1580 
1581 	mtuctl.ip6m_mtu = mtu;
1582 	mtuctl.ip6m_addr = *dst;
1583 	if (sa6_recoverscope(&mtuctl.ip6m_addr))
1584 		return;
1585 
1586 	if ((m_mtu = sbcreatecontrol((caddr_t)&mtuctl, sizeof(mtuctl),
1587 	    IPV6_PATHMTU, IPPROTO_IPV6)) == NULL)
1588 		return;
1589 
1590 	so =  inp->inp_socket;
1591 	if (sbappendaddr(&so->so_rcv, (struct sockaddr *)dst, NULL, m_mtu)
1592 	    == 0) {
1593 		soroverflow(so);
1594 		m_freem(m_mtu);
1595 		/* XXX: should count statistics */
1596 	} else
1597 		sorwakeup(so);
1598 }
1599 
1600 /*
1601  * Get pointer to the previous header followed by the header
1602  * currently processed.
1603  */
1604 int
1605 ip6_get_prevhdr(const struct mbuf *m, int off)
1606 {
1607 	struct ip6_ext ip6e;
1608 	struct ip6_hdr *ip6;
1609 	int len, nlen, nxt;
1610 
1611 	if (off == sizeof(struct ip6_hdr))
1612 		return (offsetof(struct ip6_hdr, ip6_nxt));
1613 	if (off < sizeof(struct ip6_hdr))
1614 		panic("%s: off < sizeof(struct ip6_hdr)", __func__);
1615 
1616 	ip6 = mtod(m, struct ip6_hdr *);
1617 	nxt = ip6->ip6_nxt;
1618 	len = sizeof(struct ip6_hdr);
1619 	nlen = 0;
1620 	while (len < off) {
1621 		m_copydata(m, len, sizeof(ip6e), (caddr_t)&ip6e);
1622 		switch (nxt) {
1623 		case IPPROTO_FRAGMENT:
1624 			nlen = sizeof(struct ip6_frag);
1625 			break;
1626 		case IPPROTO_AH:
1627 			nlen = (ip6e.ip6e_len + 2) << 2;
1628 			break;
1629 		default:
1630 			nlen = (ip6e.ip6e_len + 1) << 3;
1631 		}
1632 		len += nlen;
1633 		nxt = ip6e.ip6e_nxt;
1634 	}
1635 	return (len - nlen);
1636 }
1637 
1638 /*
1639  * get next header offset.  m will be retained.
1640  */
1641 int
1642 ip6_nexthdr(const struct mbuf *m, int off, int proto, int *nxtp)
1643 {
1644 	struct ip6_hdr ip6;
1645 	struct ip6_ext ip6e;
1646 	struct ip6_frag fh;
1647 
1648 	/* just in case */
1649 	if (m == NULL)
1650 		panic("ip6_nexthdr: m == NULL");
1651 	if ((m->m_flags & M_PKTHDR) == 0 || m->m_pkthdr.len < off)
1652 		return -1;
1653 
1654 	switch (proto) {
1655 	case IPPROTO_IPV6:
1656 		if (m->m_pkthdr.len < off + sizeof(ip6))
1657 			return -1;
1658 		m_copydata(m, off, sizeof(ip6), (caddr_t)&ip6);
1659 		if (nxtp)
1660 			*nxtp = ip6.ip6_nxt;
1661 		off += sizeof(ip6);
1662 		return off;
1663 
1664 	case IPPROTO_FRAGMENT:
1665 		/*
1666 		 * terminate parsing if it is not the first fragment,
1667 		 * it does not make sense to parse through it.
1668 		 */
1669 		if (m->m_pkthdr.len < off + sizeof(fh))
1670 			return -1;
1671 		m_copydata(m, off, sizeof(fh), (caddr_t)&fh);
1672 		/* IP6F_OFF_MASK = 0xfff8(BigEndian), 0xf8ff(LittleEndian) */
1673 		if (fh.ip6f_offlg & IP6F_OFF_MASK)
1674 			return -1;
1675 		if (nxtp)
1676 			*nxtp = fh.ip6f_nxt;
1677 		off += sizeof(struct ip6_frag);
1678 		return off;
1679 
1680 	case IPPROTO_AH:
1681 		if (m->m_pkthdr.len < off + sizeof(ip6e))
1682 			return -1;
1683 		m_copydata(m, off, sizeof(ip6e), (caddr_t)&ip6e);
1684 		if (nxtp)
1685 			*nxtp = ip6e.ip6e_nxt;
1686 		off += (ip6e.ip6e_len + 2) << 2;
1687 		return off;
1688 
1689 	case IPPROTO_HOPOPTS:
1690 	case IPPROTO_ROUTING:
1691 	case IPPROTO_DSTOPTS:
1692 		if (m->m_pkthdr.len < off + sizeof(ip6e))
1693 			return -1;
1694 		m_copydata(m, off, sizeof(ip6e), (caddr_t)&ip6e);
1695 		if (nxtp)
1696 			*nxtp = ip6e.ip6e_nxt;
1697 		off += (ip6e.ip6e_len + 1) << 3;
1698 		return off;
1699 
1700 	case IPPROTO_NONE:
1701 	case IPPROTO_ESP:
1702 	case IPPROTO_IPCOMP:
1703 		/* give up */
1704 		return -1;
1705 
1706 	default:
1707 		return -1;
1708 	}
1709 
1710 	/* NOTREACHED */
1711 }
1712 
1713 /*
1714  * get offset for the last header in the chain.  m will be kept untainted.
1715  */
1716 int
1717 ip6_lasthdr(const struct mbuf *m, int off, int proto, int *nxtp)
1718 {
1719 	int newoff;
1720 	int nxt;
1721 
1722 	if (!nxtp) {
1723 		nxt = -1;
1724 		nxtp = &nxt;
1725 	}
1726 	while (1) {
1727 		newoff = ip6_nexthdr(m, off, proto, nxtp);
1728 		if (newoff < 0)
1729 			return off;
1730 		else if (newoff < off)
1731 			return -1;	/* invalid */
1732 		else if (newoff == off)
1733 			return newoff;
1734 
1735 		off = newoff;
1736 		proto = *nxtp;
1737 	}
1738 }
1739 
1740 /*
1741  * System control for IP6
1742  */
1743 
1744 u_char	inet6ctlerrmap[PRC_NCMDS] = {
1745 	0,		0,		0,		0,
1746 	0,		EMSGSIZE,	EHOSTDOWN,	EHOSTUNREACH,
1747 	EHOSTUNREACH,	EHOSTUNREACH,	ECONNREFUSED,	ECONNREFUSED,
1748 	EMSGSIZE,	EHOSTUNREACH,	0,		0,
1749 	0,		0,		EHOSTUNREACH,	0,
1750 	ENOPROTOOPT,	ECONNREFUSED
1751 };
1752