xref: /freebsd/sys/netinet6/ip6_input.c (revision 467d3e2e8aa3157794d0c7adc7884b1c4a5535c1)
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 			struct ifnet *ifp = (m->m_flags & M_LOOP) ? V_loif : rcvif;
592 			int ifindex = ifp->if_index;
593 			if (ifindex >= IP6S_M2MMAX)
594 				ifindex = 0;
595 			IP6STAT_INC(ip6s_m2m[ifindex]);
596 		} else
597 			IP6STAT_INC(ip6s_m1);
598 	}
599 
600 	in6_ifstat_inc(rcvif, ifs6_in_receive);
601 	IP6STAT_INC(ip6s_total);
602 
603 	/*
604 	 * L2 bridge code and some other code can return mbuf chain
605 	 * that does not conform to KAME requirement.  too bad.
606 	 * XXX: fails to join if interface MTU > MCLBYTES.  jumbogram?
607 	 */
608 	if (m && m->m_next != NULL && m->m_pkthdr.len < MCLBYTES) {
609 		struct mbuf *n;
610 
611 		if (m->m_pkthdr.len > MHLEN)
612 			n = m_getcl(M_NOWAIT, MT_DATA, M_PKTHDR);
613 		else
614 			n = m_gethdr(M_NOWAIT, MT_DATA);
615 		if (n == NULL)
616 			goto bad;
617 
618 		m_move_pkthdr(n, m);
619 		m_copydata(m, 0, n->m_pkthdr.len, mtod(n, caddr_t));
620 		n->m_len = n->m_pkthdr.len;
621 		m_freem(m);
622 		m = n;
623 	}
624 	if (m->m_len < sizeof(struct ip6_hdr)) {
625 		if ((m = m_pullup(m, sizeof(struct ip6_hdr))) == NULL) {
626 			IP6STAT_INC(ip6s_toosmall);
627 			in6_ifstat_inc(rcvif, ifs6_in_hdrerr);
628 			goto bad;
629 		}
630 	}
631 
632 	ip6 = mtod(m, struct ip6_hdr *);
633 	if ((ip6->ip6_vfc & IPV6_VERSION_MASK) != IPV6_VERSION) {
634 		IP6STAT_INC(ip6s_badvers);
635 		in6_ifstat_inc(rcvif, ifs6_in_hdrerr);
636 		goto bad;
637 	}
638 
639 	IP6STAT_INC(ip6s_nxthist[ip6->ip6_nxt]);
640 	IP_PROBE(receive, NULL, NULL, ip6, rcvif, NULL, ip6);
641 
642 	/*
643 	 * Check against address spoofing/corruption.
644 	 */
645 	if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_src) ||
646 	    IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_dst)) {
647 		/*
648 		 * XXX: "badscope" is not very suitable for a multicast source.
649 		 */
650 		IP6STAT_INC(ip6s_badscope);
651 		in6_ifstat_inc(rcvif, ifs6_in_addrerr);
652 		goto bad;
653 	}
654 	if (IN6_IS_ADDR_MC_INTFACELOCAL(&ip6->ip6_dst) &&
655 	    !(m->m_flags & M_LOOP)) {
656 		/*
657 		 * In this case, the packet should come from the loopback
658 		 * interface.  However, we cannot just check the if_flags,
659 		 * because ip6_mloopback() passes the "actual" interface
660 		 * as the outgoing/incoming interface.
661 		 */
662 		IP6STAT_INC(ip6s_badscope);
663 		in6_ifstat_inc(rcvif, ifs6_in_addrerr);
664 		goto bad;
665 	}
666 	if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) &&
667 	    IPV6_ADDR_MC_SCOPE(&ip6->ip6_dst) == 0) {
668 		/*
669 		 * RFC4291 2.7:
670 		 * Nodes must not originate a packet to a multicast address
671 		 * whose scop field contains the reserved value 0; if such
672 		 * a packet is received, it must be silently dropped.
673 		 */
674 		IP6STAT_INC(ip6s_badscope);
675 		in6_ifstat_inc(rcvif, ifs6_in_addrerr);
676 		goto bad;
677 	}
678 #ifdef ALTQ
679 	if (altq_input != NULL && (*altq_input)(m, AF_INET6) == 0) {
680 		/* packet is dropped by traffic conditioner */
681 		return;
682 	}
683 #endif
684 	/*
685 	 * The following check is not documented in specs.  A malicious
686 	 * party may be able to use IPv4 mapped addr to confuse tcp/udp stack
687 	 * and bypass security checks (act as if it was from 127.0.0.1 by using
688 	 * IPv6 src ::ffff:127.0.0.1).  Be cautious.
689 	 *
690 	 * We have supported IPv6-only kernels for a few years and this issue
691 	 * has not come up.  The world seems to move mostly towards not using
692 	 * v4mapped on the wire, so it makes sense for us to keep rejecting
693 	 * any such packets.
694 	 */
695 	if (IN6_IS_ADDR_V4MAPPED(&ip6->ip6_src) ||
696 	    IN6_IS_ADDR_V4MAPPED(&ip6->ip6_dst)) {
697 		IP6STAT_INC(ip6s_badscope);
698 		in6_ifstat_inc(rcvif, ifs6_in_addrerr);
699 		goto bad;
700 	}
701 #if 0
702 	/*
703 	 * Reject packets with IPv4 compatible addresses (auto tunnel).
704 	 *
705 	 * The code forbids auto tunnel relay case in RFC1933 (the check is
706 	 * stronger than RFC1933).  We may want to re-enable it if mech-xx
707 	 * is revised to forbid relaying case.
708 	 */
709 	if (IN6_IS_ADDR_V4COMPAT(&ip6->ip6_src) ||
710 	    IN6_IS_ADDR_V4COMPAT(&ip6->ip6_dst)) {
711 		IP6STAT_INC(ip6s_badscope);
712 		in6_ifstat_inc(m->m_pkthdr.rcvif, ifs6_in_addrerr);
713 		goto bad;
714 	}
715 #endif
716 	/*
717 	 * Try to forward the packet, but if we fail continue.
718 	 * ip6_tryforward() does not generate redirects, so fall
719 	 * through to normal processing if redirects are required.
720 	 * ip6_tryforward() does inbound and outbound packet firewall
721 	 * processing. If firewall has decided that destination becomes
722 	 * our local address, it sets M_FASTFWD_OURS flag. In this
723 	 * case skip another inbound firewall processing and update
724 	 * ip6 pointer.
725 	 */
726 	if (V_ip6_forwarding != 0 && V_ip6_sendredirects == 0
727 #if defined(IPSEC) || defined(IPSEC_SUPPORT)
728 	    && (!IPSEC_ENABLED(ipv6) ||
729 	    IPSEC_CAPS(ipv6, m, IPSEC_CAP_OPERABLE) == 0)
730 #endif
731 	    ) {
732 		if ((m = ip6_tryforward(m)) == NULL)
733 			return;
734 		if (m->m_flags & M_FASTFWD_OURS) {
735 			ip6 = mtod(m, struct ip6_hdr *);
736 			goto passin;
737 		}
738 	}
739 #if defined(IPSEC) || defined(IPSEC_SUPPORT)
740 	/*
741 	 * Bypass packet filtering for packets previously handled by IPsec.
742 	 */
743 	if (IPSEC_ENABLED(ipv6) &&
744 	    IPSEC_CAPS(ipv6, m, IPSEC_CAP_BYPASS_FILTER) != 0)
745 			goto passin;
746 #endif
747 	/*
748 	 * Run through list of hooks for input packets.
749 	 *
750 	 * NB: Beware of the destination address changing
751 	 *     (e.g. by NAT rewriting).  When this happens,
752 	 *     tell ip6_forward to do the right thing.
753 	 */
754 
755 	/* Jump over all PFIL processing if hooks are not active. */
756 	if (!PFIL_HOOKED_IN(V_inet6_pfil_head))
757 		goto passin;
758 
759 	odst = ip6->ip6_dst;
760 	if (pfil_run_hooks(V_inet6_pfil_head, &m, m->m_pkthdr.rcvif, PFIL_IN,
761 	    NULL) != PFIL_PASS)
762 		return;
763 	ip6 = mtod(m, struct ip6_hdr *);
764 	srcrt = !IN6_ARE_ADDR_EQUAL(&odst, &ip6->ip6_dst);
765 	if ((m->m_flags & (M_IP6_NEXTHOP | M_FASTFWD_OURS)) == M_IP6_NEXTHOP &&
766 	    m_tag_find(m, PACKET_TAG_IPFORWARD, NULL) != NULL) {
767 		/*
768 		 * Directly ship the packet on.  This allows forwarding
769 		 * packets originally destined to us to some other directly
770 		 * connected host.
771 		 */
772 		ip6_forward(m, 1);
773 		return;
774 	}
775 
776 passin:
777 	/*
778 	 * Disambiguate address scope zones (if there is ambiguity).
779 	 * We first make sure that the original source or destination address
780 	 * is not in our internal form for scoped addresses.  Such addresses
781 	 * are not necessarily invalid spec-wise, but we cannot accept them due
782 	 * to the usage conflict.
783 	 * in6_setscope() then also checks and rejects the cases where src or
784 	 * dst are the loopback address and the receiving interface
785 	 * is not loopback.
786 	 */
787 	if (in6_clearscope(&ip6->ip6_src) || in6_clearscope(&ip6->ip6_dst)) {
788 		IP6STAT_INC(ip6s_badscope); /* XXX */
789 		goto bad;
790 	}
791 	if (in6_setscope(&ip6->ip6_src, rcvif, NULL) ||
792 	    in6_setscope(&ip6->ip6_dst, rcvif, NULL)) {
793 		IP6STAT_INC(ip6s_badscope);
794 		goto bad;
795 	}
796 	if (m->m_flags & M_FASTFWD_OURS) {
797 		m->m_flags &= ~M_FASTFWD_OURS;
798 		ours = 1;
799 		goto hbhcheck;
800 	}
801 	/*
802 	 * Multicast check. Assume packet is for us to avoid
803 	 * prematurely taking locks.
804 	 */
805 	if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) {
806 		ours = 1;
807 		in6_ifstat_inc(rcvif, ifs6_in_mcast);
808 		goto hbhcheck;
809 	}
810 	/*
811 	 * Unicast check
812 	 * XXX: For now we keep link-local IPv6 addresses with embedded
813 	 *      scope zone id, therefore we use zero zoneid here.
814 	 */
815 	ia = in6ifa_ifwithaddr(&ip6->ip6_dst, 0 /* XXX */, false);
816 	if (ia != NULL) {
817 		if (ia->ia6_flags & IN6_IFF_NOTREADY) {
818 			char ip6bufs[INET6_ADDRSTRLEN];
819 			char ip6bufd[INET6_ADDRSTRLEN];
820 			/* address is not ready, so discard the packet. */
821 			nd6log((LOG_INFO,
822 			    "ip6_input: packet to an unready address %s->%s\n",
823 			    ip6_sprintf(ip6bufs, &ip6->ip6_src),
824 			    ip6_sprintf(ip6bufd, &ip6->ip6_dst)));
825 			goto bad;
826 		}
827 		if (V_ip6_sav && !(m->m_flags & M_LOOP) &&
828 		    __predict_false(in6_localip_fib(&ip6->ip6_src,
829 			    rcvif->if_fib))) {
830 			IP6STAT_INC(ip6s_badscope); /* XXX */
831 			goto bad;
832 		}
833 		/* Count the packet in the ip address stats */
834 		counter_u64_add(ia->ia_ifa.ifa_ipackets, 1);
835 		counter_u64_add(ia->ia_ifa.ifa_ibytes, m->m_pkthdr.len);
836 		ours = 1;
837 		goto hbhcheck;
838 	}
839 
840 	/*
841 	 * Now there is no reason to process the packet if it's not our own
842 	 * and we're not a router.
843 	 */
844 	if (!V_ip6_forwarding) {
845 		IP6STAT_INC(ip6s_cantforward);
846 		goto bad;
847 	}
848 
849   hbhcheck:
850 	/*
851 	 * Process Hop-by-Hop options header if it's contained.
852 	 * m may be modified in ip6_hopopts_input().
853 	 * If a JumboPayload option is included, plen will also be modified.
854 	 */
855 	plen = (u_int32_t)ntohs(ip6->ip6_plen);
856 	if (ip6->ip6_nxt == IPPROTO_HOPOPTS) {
857 		if (ip6_input_hbh(&m, &plen, &rtalert, &off, &nxt, &ours) != 0)
858 			return;
859 	} else
860 		nxt = ip6->ip6_nxt;
861 
862 	/*
863 	 * Use mbuf flags to propagate Router Alert option to
864 	 * ICMPv6 layer, as hop-by-hop options have been stripped.
865 	 */
866 	if (rtalert != ~0)
867 		m->m_flags |= M_RTALERT_MLD;
868 
869 	/*
870 	 * Check that the amount of data in the buffers
871 	 * is as at least much as the IPv6 header would have us expect.
872 	 * Trim mbufs if longer than we expect.
873 	 * Drop packet if shorter than we expect.
874 	 */
875 	if (m->m_pkthdr.len - sizeof(struct ip6_hdr) < plen) {
876 		IP6STAT_INC(ip6s_tooshort);
877 		in6_ifstat_inc(rcvif, ifs6_in_truncated);
878 		goto bad;
879 	}
880 	if (m->m_pkthdr.len > sizeof(struct ip6_hdr) + plen) {
881 		if (m->m_len == m->m_pkthdr.len) {
882 			m->m_len = sizeof(struct ip6_hdr) + plen;
883 			m->m_pkthdr.len = sizeof(struct ip6_hdr) + plen;
884 		} else
885 			m_adj(m, sizeof(struct ip6_hdr) + plen - m->m_pkthdr.len);
886 	}
887 
888 	/*
889 	 * Forward if desirable.
890 	 */
891 	if (V_ip6_mrouter &&
892 	    IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst)) {
893 		/*
894 		 * If we are acting as a multicast router, all
895 		 * incoming multicast packets are passed to the
896 		 * kernel-level multicast forwarding function.
897 		 * The packet is returned (relatively) intact; if
898 		 * ip6_mforward() returns a non-zero value, the packet
899 		 * must be discarded, else it may be accepted below.
900 		 *
901 		 * XXX TODO: Check hlim and multicast scope here to avoid
902 		 * unnecessarily calling into ip6_mforward().
903 		 */
904 		if (ip6_mforward && ip6_mforward(ip6, rcvif, m)) {
905 			IP6STAT_INC(ip6s_cantforward);
906 			goto bad;
907 		}
908 	} else if (!ours) {
909 		ip6_forward(m, srcrt);
910 		return;
911 	}
912 
913 	/*
914 	 * Tell launch routine the next header
915 	 */
916 	IP6STAT_INC(ip6s_delivered);
917 	in6_ifstat_inc(rcvif, ifs6_in_deliver);
918 	nest = 0;
919 
920 	while (nxt != IPPROTO_DONE) {
921 		if (V_ip6_hdrnestlimit && (++nest > V_ip6_hdrnestlimit)) {
922 			IP6STAT_INC(ip6s_toomanyhdr);
923 			goto bad;
924 		}
925 
926 		/*
927 		 * protection against faulty packet - there should be
928 		 * more sanity checks in header chain processing.
929 		 */
930 		if (m->m_pkthdr.len < off) {
931 			IP6STAT_INC(ip6s_tooshort);
932 			in6_ifstat_inc(rcvif, ifs6_in_truncated);
933 			goto bad;
934 		}
935 
936 #if defined(IPSEC) || defined(IPSEC_SUPPORT)
937 		if (IPSEC_ENABLED(ipv6)) {
938 			if (IPSEC_INPUT(ipv6, m, off, nxt) != 0)
939 				return;
940 		}
941 #endif /* IPSEC */
942 
943 		nxt = (*inet6sw[ip6_protox[nxt]].pr_input)(&m, &off, nxt);
944 	}
945 	return;
946 bad:
947 	in6_ifstat_inc(rcvif, ifs6_in_discard);
948 	if (m != NULL)
949 		m_freem(m);
950 }
951 
952 /*
953  * Hop-by-Hop options header processing. If a valid jumbo payload option is
954  * included, the real payload length will be stored in plenp.
955  *
956  * rtalertp - XXX: should be stored more smart way
957  */
958 static int
959 ip6_hopopts_input(u_int32_t *plenp, u_int32_t *rtalertp,
960     struct mbuf **mp, int *offp)
961 {
962 	struct mbuf *m = *mp;
963 	int off = *offp, hbhlen;
964 	struct ip6_hbh *hbh;
965 
966 	/* validation of the length of the header */
967 	if (m->m_len < off + sizeof(*hbh)) {
968 		m = m_pullup(m, off + sizeof(*hbh));
969 		if (m == NULL) {
970 			IP6STAT_INC(ip6s_exthdrtoolong);
971 			*mp = NULL;
972 			return (-1);
973 		}
974 	}
975 	hbh = (struct ip6_hbh *)(mtod(m, caddr_t) + off);
976 	hbhlen = (hbh->ip6h_len + 1) << 3;
977 
978 	if (m->m_len < off + hbhlen) {
979 		m = m_pullup(m, off + hbhlen);
980 		if (m == NULL) {
981 			IP6STAT_INC(ip6s_exthdrtoolong);
982 			*mp = NULL;
983 			return (-1);
984 		}
985 	}
986 	hbh = (struct ip6_hbh *)(mtod(m, caddr_t) + off);
987 	off += hbhlen;
988 	hbhlen -= sizeof(struct ip6_hbh);
989 	if (ip6_process_hopopts(m, (u_int8_t *)hbh + sizeof(struct ip6_hbh),
990 				hbhlen, rtalertp, plenp) < 0) {
991 		*mp = NULL;
992 		return (-1);
993 	}
994 
995 	*offp = off;
996 	*mp = m;
997 	return (0);
998 }
999 
1000 /*
1001  * Search header for all Hop-by-hop options and process each option.
1002  * This function is separate from ip6_hopopts_input() in order to
1003  * handle a case where the sending node itself process its hop-by-hop
1004  * options header. In such a case, the function is called from ip6_output().
1005  *
1006  * The function assumes that hbh header is located right after the IPv6 header
1007  * (RFC2460 p7), opthead is pointer into data content in m, and opthead to
1008  * opthead + hbhlen is located in contiguous memory region.
1009  */
1010 int
1011 ip6_process_hopopts(struct mbuf *m, u_int8_t *opthead, int hbhlen,
1012     u_int32_t *rtalertp, u_int32_t *plenp)
1013 {
1014 	struct ip6_hdr *ip6;
1015 	int optlen = 0;
1016 	u_int8_t *opt = opthead;
1017 	u_int16_t rtalert_val;
1018 	u_int32_t jumboplen;
1019 	const int erroff = sizeof(struct ip6_hdr) + sizeof(struct ip6_hbh);
1020 
1021 	for (; hbhlen > 0; hbhlen -= optlen, opt += optlen) {
1022 		switch (*opt) {
1023 		case IP6OPT_PAD1:
1024 			optlen = 1;
1025 			break;
1026 		case IP6OPT_PADN:
1027 			if (hbhlen < IP6OPT_MINLEN) {
1028 				IP6STAT_INC(ip6s_toosmall);
1029 				goto bad;
1030 			}
1031 			optlen = *(opt + 1) + 2;
1032 			break;
1033 		case IP6OPT_ROUTER_ALERT:
1034 			/* XXX may need check for alignment */
1035 			if (hbhlen < IP6OPT_RTALERT_LEN) {
1036 				IP6STAT_INC(ip6s_toosmall);
1037 				goto bad;
1038 			}
1039 			if (*(opt + 1) != IP6OPT_RTALERT_LEN - 2) {
1040 				/* XXX stat */
1041 				icmp6_error(m, ICMP6_PARAM_PROB,
1042 				    ICMP6_PARAMPROB_HEADER,
1043 				    erroff + opt + 1 - opthead);
1044 				return (-1);
1045 			}
1046 			optlen = IP6OPT_RTALERT_LEN;
1047 			bcopy((caddr_t)(opt + 2), (caddr_t)&rtalert_val, 2);
1048 			*rtalertp = ntohs(rtalert_val);
1049 			break;
1050 		case IP6OPT_JUMBO:
1051 			/* XXX may need check for alignment */
1052 			if (hbhlen < IP6OPT_JUMBO_LEN) {
1053 				IP6STAT_INC(ip6s_toosmall);
1054 				goto bad;
1055 			}
1056 			if (*(opt + 1) != IP6OPT_JUMBO_LEN - 2) {
1057 				/* XXX stat */
1058 				icmp6_error(m, ICMP6_PARAM_PROB,
1059 				    ICMP6_PARAMPROB_HEADER,
1060 				    erroff + opt + 1 - opthead);
1061 				return (-1);
1062 			}
1063 			optlen = IP6OPT_JUMBO_LEN;
1064 
1065 			/*
1066 			 * IPv6 packets that have non 0 payload length
1067 			 * must not contain a jumbo payload option.
1068 			 */
1069 			ip6 = mtod(m, struct ip6_hdr *);
1070 			if (ip6->ip6_plen) {
1071 				IP6STAT_INC(ip6s_badoptions);
1072 				icmp6_error(m, ICMP6_PARAM_PROB,
1073 				    ICMP6_PARAMPROB_HEADER,
1074 				    erroff + opt - opthead);
1075 				return (-1);
1076 			}
1077 
1078 			/*
1079 			 * We may see jumbolen in unaligned location, so
1080 			 * we'd need to perform bcopy().
1081 			 */
1082 			bcopy(opt + 2, &jumboplen, sizeof(jumboplen));
1083 			jumboplen = (u_int32_t)htonl(jumboplen);
1084 
1085 #if 1
1086 			/*
1087 			 * if there are multiple jumbo payload options,
1088 			 * *plenp will be non-zero and the packet will be
1089 			 * rejected.
1090 			 * the behavior may need some debate in ipngwg -
1091 			 * multiple options does not make sense, however,
1092 			 * there's no explicit mention in specification.
1093 			 */
1094 			if (*plenp != 0) {
1095 				IP6STAT_INC(ip6s_badoptions);
1096 				icmp6_error(m, ICMP6_PARAM_PROB,
1097 				    ICMP6_PARAMPROB_HEADER,
1098 				    erroff + opt + 2 - opthead);
1099 				return (-1);
1100 			}
1101 #endif
1102 
1103 			/*
1104 			 * jumbo payload length must be larger than 65535.
1105 			 */
1106 			if (jumboplen <= IPV6_MAXPACKET) {
1107 				IP6STAT_INC(ip6s_badoptions);
1108 				icmp6_error(m, ICMP6_PARAM_PROB,
1109 				    ICMP6_PARAMPROB_HEADER,
1110 				    erroff + opt + 2 - opthead);
1111 				return (-1);
1112 			}
1113 			*plenp = jumboplen;
1114 
1115 			break;
1116 		default:		/* unknown option */
1117 			if (hbhlen < IP6OPT_MINLEN) {
1118 				IP6STAT_INC(ip6s_toosmall);
1119 				goto bad;
1120 			}
1121 			optlen = ip6_unknown_opt(opt, m,
1122 			    erroff + opt - opthead);
1123 			if (optlen == -1)
1124 				return (-1);
1125 			optlen += 2;
1126 			break;
1127 		}
1128 	}
1129 
1130 	return (0);
1131 
1132   bad:
1133 	m_freem(m);
1134 	return (-1);
1135 }
1136 
1137 /*
1138  * Unknown option processing.
1139  * The third argument `off' is the offset from the IPv6 header to the option,
1140  * which is necessary if the IPv6 header the and option header and IPv6 header
1141  * is not contiguous in order to return an ICMPv6 error.
1142  */
1143 int
1144 ip6_unknown_opt(u_int8_t *optp, struct mbuf *m, int off)
1145 {
1146 	struct ip6_hdr *ip6;
1147 
1148 	switch (IP6OPT_TYPE(*optp)) {
1149 	case IP6OPT_TYPE_SKIP: /* ignore the option */
1150 		return ((int)*(optp + 1));
1151 	case IP6OPT_TYPE_DISCARD:	/* silently discard */
1152 		m_freem(m);
1153 		return (-1);
1154 	case IP6OPT_TYPE_FORCEICMP: /* send ICMP even if multicasted */
1155 		IP6STAT_INC(ip6s_badoptions);
1156 		icmp6_error(m, ICMP6_PARAM_PROB, ICMP6_PARAMPROB_OPTION, off);
1157 		return (-1);
1158 	case IP6OPT_TYPE_ICMP: /* send ICMP if not multicasted */
1159 		IP6STAT_INC(ip6s_badoptions);
1160 		ip6 = mtod(m, struct ip6_hdr *);
1161 		if (IN6_IS_ADDR_MULTICAST(&ip6->ip6_dst) ||
1162 		    (m->m_flags & (M_BCAST|M_MCAST)))
1163 			m_freem(m);
1164 		else
1165 			icmp6_error(m, ICMP6_PARAM_PROB,
1166 				    ICMP6_PARAMPROB_OPTION, off);
1167 		return (-1);
1168 	}
1169 
1170 	m_freem(m);		/* XXX: NOTREACHED */
1171 	return (-1);
1172 }
1173 
1174 /*
1175  * Create the "control" list for this pcb.
1176  * These functions will not modify mbuf chain at all.
1177  *
1178  * The routine will be called from upper layer handlers like tcp6_input().
1179  * Thus the routine assumes that the caller (tcp6_input) have already
1180  * called m_pullup() and all the extension headers are located in the
1181  * very first mbuf on the mbuf chain.
1182  *
1183  * ip6_savecontrol_v4 will handle those options that are possible to be
1184  * set on a v4-mapped socket.
1185  * ip6_savecontrol will directly call ip6_savecontrol_v4 to handle those
1186  * options and handle the v6-only ones itself.
1187  */
1188 struct mbuf **
1189 ip6_savecontrol_v4(struct inpcb *inp, struct mbuf *m, struct mbuf **mp,
1190     int *v4only)
1191 {
1192 	struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
1193 
1194 #ifdef SO_TIMESTAMP
1195 	if ((inp->inp_socket->so_options & SO_TIMESTAMP) != 0) {
1196 		union {
1197 			struct timeval tv;
1198 			struct bintime bt;
1199 			struct timespec ts;
1200 		} t;
1201 		struct bintime boottimebin, bt1;
1202 		struct timespec ts1;
1203 		bool stamped;
1204 
1205 		stamped = false;
1206 		switch (inp->inp_socket->so_ts_clock) {
1207 		case SO_TS_REALTIME_MICRO:
1208 			if ((m->m_flags & (M_PKTHDR | M_TSTMP)) == (M_PKTHDR |
1209 			    M_TSTMP)) {
1210 				mbuf_tstmp2timespec(m, &ts1);
1211 				timespec2bintime(&ts1, &bt1);
1212 				getboottimebin(&boottimebin);
1213 				bintime_add(&bt1, &boottimebin);
1214 				bintime2timeval(&bt1, &t.tv);
1215 			} else {
1216 				microtime(&t.tv);
1217 			}
1218 			*mp = sbcreatecontrol(&t.tv, sizeof(t.tv),
1219 			    SCM_TIMESTAMP, SOL_SOCKET, M_NOWAIT);
1220 			if (*mp != NULL) {
1221 				mp = &(*mp)->m_next;
1222 				stamped = true;
1223 			}
1224 			break;
1225 
1226 		case SO_TS_BINTIME:
1227 			if ((m->m_flags & (M_PKTHDR | M_TSTMP)) == (M_PKTHDR |
1228 			    M_TSTMP)) {
1229 				mbuf_tstmp2timespec(m, &ts1);
1230 				timespec2bintime(&ts1, &t.bt);
1231 				getboottimebin(&boottimebin);
1232 				bintime_add(&t.bt, &boottimebin);
1233 			} else {
1234 				bintime(&t.bt);
1235 			}
1236 			*mp = sbcreatecontrol(&t.bt, sizeof(t.bt), SCM_BINTIME,
1237 			    SOL_SOCKET, M_NOWAIT);
1238 			if (*mp != NULL) {
1239 				mp = &(*mp)->m_next;
1240 				stamped = true;
1241 			}
1242 			break;
1243 
1244 		case SO_TS_REALTIME:
1245 			if ((m->m_flags & (M_PKTHDR | M_TSTMP)) == (M_PKTHDR |
1246 			    M_TSTMP)) {
1247 				mbuf_tstmp2timespec(m, &t.ts);
1248 				getboottimebin(&boottimebin);
1249 				bintime2timespec(&boottimebin, &ts1);
1250 				timespecadd(&t.ts, &ts1, &t.ts);
1251 			} else {
1252 				nanotime(&t.ts);
1253 			}
1254 			*mp = sbcreatecontrol(&t.ts, sizeof(t.ts),
1255 			    SCM_REALTIME, SOL_SOCKET, M_NOWAIT);
1256 			if (*mp != NULL) {
1257 				mp = &(*mp)->m_next;
1258 				stamped = true;
1259 			}
1260 			break;
1261 
1262 		case SO_TS_MONOTONIC:
1263 			if ((m->m_flags & (M_PKTHDR | M_TSTMP)) == (M_PKTHDR |
1264 			    M_TSTMP))
1265 				mbuf_tstmp2timespec(m, &t.ts);
1266 			else
1267 				nanouptime(&t.ts);
1268 			*mp = sbcreatecontrol(&t.ts, sizeof(t.ts),
1269 			    SCM_MONOTONIC, SOL_SOCKET, M_NOWAIT);
1270 			if (*mp != NULL) {
1271 				mp = &(*mp)->m_next;
1272 				stamped = true;
1273 			}
1274 			break;
1275 
1276 		default:
1277 			panic("unknown (corrupted) so_ts_clock");
1278 		}
1279 		if (stamped && (m->m_flags & (M_PKTHDR | M_TSTMP)) ==
1280 		    (M_PKTHDR | M_TSTMP)) {
1281 			struct sock_timestamp_info sti;
1282 
1283 			bzero(&sti, sizeof(sti));
1284 			sti.st_info_flags = ST_INFO_HW;
1285 			if ((m->m_flags & M_TSTMP_HPREC) != 0)
1286 				sti.st_info_flags |= ST_INFO_HW_HPREC;
1287 			*mp = sbcreatecontrol(&sti, sizeof(sti), SCM_TIME_INFO,
1288 			    SOL_SOCKET, M_NOWAIT);
1289 			if (*mp != NULL)
1290 				mp = &(*mp)->m_next;
1291 		}
1292 	}
1293 #endif
1294 
1295 #define IS2292(inp, x, y)	(((inp)->inp_flags & IN6P_RFC2292) ? (x) : (y))
1296 	/* RFC 2292 sec. 5 */
1297 	if ((inp->inp_flags & IN6P_PKTINFO) != 0) {
1298 		struct in6_pktinfo pi6;
1299 
1300 		if ((ip6->ip6_vfc & IPV6_VERSION_MASK) != IPV6_VERSION) {
1301 #ifdef INET
1302 			struct ip *ip;
1303 
1304 			ip = mtod(m, struct ip *);
1305 			pi6.ipi6_addr.s6_addr32[0] = 0;
1306 			pi6.ipi6_addr.s6_addr32[1] = 0;
1307 			pi6.ipi6_addr.s6_addr32[2] = IPV6_ADDR_INT32_SMP;
1308 			pi6.ipi6_addr.s6_addr32[3] = ip->ip_dst.s_addr;
1309 #else
1310 			/* We won't hit this code */
1311 			bzero(&pi6.ipi6_addr, sizeof(struct in6_addr));
1312 #endif
1313 		} else {
1314 			bcopy(&ip6->ip6_dst, &pi6.ipi6_addr, sizeof(struct in6_addr));
1315 			in6_clearscope(&pi6.ipi6_addr);	/* XXX */
1316 		}
1317 		pi6.ipi6_ifindex =
1318 		    (m && m->m_pkthdr.rcvif) ? m->m_pkthdr.rcvif->if_index : 0;
1319 
1320 		*mp = sbcreatecontrol(&pi6, sizeof(struct in6_pktinfo),
1321 		    IS2292(inp, IPV6_2292PKTINFO, IPV6_PKTINFO), IPPROTO_IPV6,
1322 		    M_NOWAIT);
1323 		if (*mp)
1324 			mp = &(*mp)->m_next;
1325 	}
1326 
1327 	if ((inp->inp_flags & IN6P_HOPLIMIT) != 0) {
1328 		int hlim;
1329 
1330 		if ((ip6->ip6_vfc & IPV6_VERSION_MASK) != IPV6_VERSION) {
1331 #ifdef INET
1332 			struct ip *ip;
1333 
1334 			ip = mtod(m, struct ip *);
1335 			hlim = ip->ip_ttl;
1336 #else
1337 			/* We won't hit this code */
1338 			hlim = 0;
1339 #endif
1340 		} else {
1341 			hlim = ip6->ip6_hlim & 0xff;
1342 		}
1343 		*mp = sbcreatecontrol(&hlim, sizeof(int),
1344 		    IS2292(inp, IPV6_2292HOPLIMIT, IPV6_HOPLIMIT),
1345 		    IPPROTO_IPV6, M_NOWAIT);
1346 		if (*mp)
1347 			mp = &(*mp)->m_next;
1348 	}
1349 
1350 	if ((inp->inp_flags & IN6P_TCLASS) != 0) {
1351 		int tclass;
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 			tclass = ip->ip_tos;
1359 #else
1360 			/* We won't hit this code */
1361 			tclass = 0;
1362 #endif
1363 		} else {
1364 			u_int32_t flowinfo;
1365 
1366 			flowinfo = (u_int32_t)ntohl(ip6->ip6_flow & IPV6_FLOWINFO_MASK);
1367 			flowinfo >>= 20;
1368 			tclass = flowinfo & 0xff;
1369 		}
1370 		*mp = sbcreatecontrol(&tclass, sizeof(int), IPV6_TCLASS,
1371 		    IPPROTO_IPV6, M_NOWAIT);
1372 		if (*mp)
1373 			mp = &(*mp)->m_next;
1374 	}
1375 
1376 	if (v4only != NULL) {
1377 		if ((ip6->ip6_vfc & IPV6_VERSION_MASK) != IPV6_VERSION) {
1378 			*v4only = 1;
1379 		} else {
1380 			*v4only = 0;
1381 		}
1382 	}
1383 
1384 	return (mp);
1385 }
1386 
1387 void
1388 ip6_savecontrol(struct inpcb *inp, struct mbuf *m, struct mbuf **mp)
1389 {
1390 	struct ip6_hdr *ip6;
1391 	int v4only = 0;
1392 
1393 	mp = ip6_savecontrol_v4(inp, m, mp, &v4only);
1394 	if (v4only)
1395 		return;
1396 
1397 	ip6 = mtod(m, struct ip6_hdr *);
1398 	/*
1399 	 * IPV6_HOPOPTS socket option.  Recall that we required super-user
1400 	 * privilege for the option (see ip6_ctloutput), but it might be too
1401 	 * strict, since there might be some hop-by-hop options which can be
1402 	 * returned to normal user.
1403 	 * See also RFC 2292 section 6 (or RFC 3542 section 8).
1404 	 */
1405 	if ((inp->inp_flags & IN6P_HOPOPTS) != 0) {
1406 		/*
1407 		 * Check if a hop-by-hop options header is contatined in the
1408 		 * received packet, and if so, store the options as ancillary
1409 		 * data. Note that a hop-by-hop options header must be
1410 		 * just after the IPv6 header, which is assured through the
1411 		 * IPv6 input processing.
1412 		 */
1413 		if (ip6->ip6_nxt == IPPROTO_HOPOPTS) {
1414 			struct ip6_hbh *hbh;
1415 			u_int hbhlen;
1416 
1417 			hbh = (struct ip6_hbh *)(ip6 + 1);
1418 			hbhlen = (hbh->ip6h_len + 1) << 3;
1419 
1420 			/*
1421 			 * XXX: We copy the whole header even if a
1422 			 * jumbo payload option is included, the option which
1423 			 * is to be removed before returning according to
1424 			 * RFC2292.
1425 			 * Note: this constraint is removed in RFC3542
1426 			 */
1427 			*mp = sbcreatecontrol(hbh, hbhlen,
1428 			    IS2292(inp, IPV6_2292HOPOPTS, IPV6_HOPOPTS),
1429 			    IPPROTO_IPV6, M_NOWAIT);
1430 			if (*mp)
1431 				mp = &(*mp)->m_next;
1432 		}
1433 	}
1434 
1435 	if ((inp->inp_flags & (IN6P_RTHDR | IN6P_DSTOPTS)) != 0) {
1436 		int nxt = ip6->ip6_nxt, off = sizeof(struct ip6_hdr);
1437 
1438 		/*
1439 		 * Search for destination options headers or routing
1440 		 * header(s) through the header chain, and stores each
1441 		 * header as ancillary data.
1442 		 * Note that the order of the headers remains in
1443 		 * the chain of ancillary data.
1444 		 */
1445 		while (1) {	/* is explicit loop prevention necessary? */
1446 			struct ip6_ext *ip6e = NULL;
1447 			u_int elen;
1448 
1449 			/*
1450 			 * if it is not an extension header, don't try to
1451 			 * pull it from the chain.
1452 			 */
1453 			switch (nxt) {
1454 			case IPPROTO_DSTOPTS:
1455 			case IPPROTO_ROUTING:
1456 			case IPPROTO_HOPOPTS:
1457 			case IPPROTO_AH: /* is it possible? */
1458 				break;
1459 			default:
1460 				goto loopend;
1461 			}
1462 
1463 			if (off + sizeof(*ip6e) > m->m_len)
1464 				goto loopend;
1465 			ip6e = (struct ip6_ext *)(mtod(m, caddr_t) + off);
1466 			if (nxt == IPPROTO_AH)
1467 				elen = (ip6e->ip6e_len + 2) << 2;
1468 			else
1469 				elen = (ip6e->ip6e_len + 1) << 3;
1470 			if (off + elen > m->m_len)
1471 				goto loopend;
1472 
1473 			switch (nxt) {
1474 			case IPPROTO_DSTOPTS:
1475 				if (!(inp->inp_flags & IN6P_DSTOPTS))
1476 					break;
1477 
1478 				*mp = sbcreatecontrol(ip6e, elen,
1479 				    IS2292(inp, IPV6_2292DSTOPTS, IPV6_DSTOPTS),
1480 				    IPPROTO_IPV6, M_NOWAIT);
1481 				if (*mp)
1482 					mp = &(*mp)->m_next;
1483 				break;
1484 			case IPPROTO_ROUTING:
1485 				if (!(inp->inp_flags & IN6P_RTHDR))
1486 					break;
1487 
1488 				*mp = sbcreatecontrol(ip6e, elen,
1489 				    IS2292(inp, IPV6_2292RTHDR, IPV6_RTHDR),
1490 				    IPPROTO_IPV6, M_NOWAIT);
1491 				if (*mp)
1492 					mp = &(*mp)->m_next;
1493 				break;
1494 			case IPPROTO_HOPOPTS:
1495 			case IPPROTO_AH: /* is it possible? */
1496 				break;
1497 
1498 			default:
1499 				/*
1500 				 * other cases have been filtered in the above.
1501 				 * none will visit this case.  here we supply
1502 				 * the code just in case (nxt overwritten or
1503 				 * other cases).
1504 				 */
1505 				goto loopend;
1506 			}
1507 
1508 			/* proceed with the next header. */
1509 			off += elen;
1510 			nxt = ip6e->ip6e_nxt;
1511 			ip6e = NULL;
1512 		}
1513 	  loopend:
1514 		;
1515 	}
1516 
1517 	if (inp->inp_flags2 & INP_RECVFLOWID) {
1518 		uint32_t flowid, flow_type;
1519 
1520 		flowid = m->m_pkthdr.flowid;
1521 		flow_type = M_HASHTYPE_GET(m);
1522 
1523 		/*
1524 		 * XXX should handle the failure of one or the
1525 		 * other - don't populate both?
1526 		 */
1527 		*mp = sbcreatecontrol(&flowid, sizeof(uint32_t), IPV6_FLOWID,
1528 		    IPPROTO_IPV6, M_NOWAIT);
1529 		if (*mp)
1530 			mp = &(*mp)->m_next;
1531 		*mp = sbcreatecontrol(&flow_type, sizeof(uint32_t),
1532 		    IPV6_FLOWTYPE, IPPROTO_IPV6, M_NOWAIT);
1533 		if (*mp)
1534 			mp = &(*mp)->m_next;
1535 	}
1536 
1537 #ifdef	RSS
1538 	if (inp->inp_flags2 & INP_RECVRSSBUCKETID) {
1539 		uint32_t flowid, flow_type;
1540 		uint32_t rss_bucketid;
1541 
1542 		flowid = m->m_pkthdr.flowid;
1543 		flow_type = M_HASHTYPE_GET(m);
1544 
1545 		if (rss_hash2bucket(flowid, flow_type, &rss_bucketid) == 0) {
1546 			*mp = sbcreatecontrol(&rss_bucketid, sizeof(uint32_t),
1547 			    IPV6_RSSBUCKETID, IPPROTO_IPV6, M_NOWAIT);
1548 			if (*mp)
1549 				mp = &(*mp)->m_next;
1550 		}
1551 	}
1552 #endif
1553 
1554 }
1555 #undef IS2292
1556 
1557 void
1558 ip6_notify_pmtu(struct inpcb *inp, struct sockaddr_in6 *dst, u_int32_t mtu)
1559 {
1560 	struct socket *so;
1561 	struct mbuf *m_mtu;
1562 	struct ip6_mtuinfo mtuctl;
1563 
1564 	KASSERT(inp != NULL, ("%s: inp == NULL", __func__));
1565 	/*
1566 	 * Notify the error by sending IPV6_PATHMTU ancillary data if
1567 	 * application wanted to know the MTU value.
1568 	 * NOTE: we notify disconnected sockets, because some udp
1569 	 * applications keep sending sockets disconnected.
1570 	 * NOTE: our implementation doesn't notify connected sockets that has
1571 	 * foreign address that is different than given destination addresses
1572 	 * (this is permitted by RFC 3542).
1573 	 */
1574 	if ((inp->inp_flags & IN6P_MTU) == 0 || (
1575 	    !IN6_IS_ADDR_UNSPECIFIED(&inp->in6p_faddr) &&
1576 	    !IN6_ARE_ADDR_EQUAL(&inp->in6p_faddr, &dst->sin6_addr)))
1577 		return;
1578 
1579 	mtuctl.ip6m_mtu = mtu;
1580 	mtuctl.ip6m_addr = *dst;
1581 	if (sa6_recoverscope(&mtuctl.ip6m_addr))
1582 		return;
1583 
1584 	if ((m_mtu = sbcreatecontrol(&mtuctl, sizeof(mtuctl), IPV6_PATHMTU,
1585 	    IPPROTO_IPV6, M_NOWAIT)) == NULL)
1586 		return;
1587 
1588 	so =  inp->inp_socket;
1589 	if (sbappendaddr(&so->so_rcv, (struct sockaddr *)dst, NULL, m_mtu)
1590 	    == 0) {
1591 		soroverflow(so);
1592 		m_freem(m_mtu);
1593 		/* XXX: should count statistics */
1594 	} else
1595 		sorwakeup(so);
1596 }
1597 
1598 /*
1599  * Get pointer to the previous header followed by the header
1600  * currently processed.
1601  */
1602 int
1603 ip6_get_prevhdr(const struct mbuf *m, int off)
1604 {
1605 	struct ip6_ext ip6e;
1606 	struct ip6_hdr *ip6;
1607 	int len, nlen, nxt;
1608 
1609 	if (off == sizeof(struct ip6_hdr))
1610 		return (offsetof(struct ip6_hdr, ip6_nxt));
1611 	if (off < sizeof(struct ip6_hdr))
1612 		panic("%s: off < sizeof(struct ip6_hdr)", __func__);
1613 
1614 	ip6 = mtod(m, struct ip6_hdr *);
1615 	nxt = ip6->ip6_nxt;
1616 	len = sizeof(struct ip6_hdr);
1617 	nlen = 0;
1618 	while (len < off) {
1619 		m_copydata(m, len, sizeof(ip6e), (caddr_t)&ip6e);
1620 		switch (nxt) {
1621 		case IPPROTO_FRAGMENT:
1622 			nlen = sizeof(struct ip6_frag);
1623 			break;
1624 		case IPPROTO_AH:
1625 			nlen = (ip6e.ip6e_len + 2) << 2;
1626 			break;
1627 		default:
1628 			nlen = (ip6e.ip6e_len + 1) << 3;
1629 		}
1630 		len += nlen;
1631 		nxt = ip6e.ip6e_nxt;
1632 	}
1633 	return (len - nlen);
1634 }
1635 
1636 /*
1637  * get next header offset.  m will be retained.
1638  */
1639 int
1640 ip6_nexthdr(const struct mbuf *m, int off, int proto, int *nxtp)
1641 {
1642 	struct ip6_hdr ip6;
1643 	struct ip6_ext ip6e;
1644 	struct ip6_frag fh;
1645 
1646 	/* just in case */
1647 	if (m == NULL)
1648 		panic("ip6_nexthdr: m == NULL");
1649 	if ((m->m_flags & M_PKTHDR) == 0 || m->m_pkthdr.len < off)
1650 		return -1;
1651 
1652 	switch (proto) {
1653 	case IPPROTO_IPV6:
1654 		if (m->m_pkthdr.len < off + sizeof(ip6))
1655 			return -1;
1656 		m_copydata(m, off, sizeof(ip6), (caddr_t)&ip6);
1657 		if (nxtp)
1658 			*nxtp = ip6.ip6_nxt;
1659 		off += sizeof(ip6);
1660 		return off;
1661 
1662 	case IPPROTO_FRAGMENT:
1663 		/*
1664 		 * terminate parsing if it is not the first fragment,
1665 		 * it does not make sense to parse through it.
1666 		 */
1667 		if (m->m_pkthdr.len < off + sizeof(fh))
1668 			return -1;
1669 		m_copydata(m, off, sizeof(fh), (caddr_t)&fh);
1670 		/* IP6F_OFF_MASK = 0xfff8(BigEndian), 0xf8ff(LittleEndian) */
1671 		if (fh.ip6f_offlg & IP6F_OFF_MASK)
1672 			return -1;
1673 		if (nxtp)
1674 			*nxtp = fh.ip6f_nxt;
1675 		off += sizeof(struct ip6_frag);
1676 		return off;
1677 
1678 	case IPPROTO_AH:
1679 		if (m->m_pkthdr.len < off + sizeof(ip6e))
1680 			return -1;
1681 		m_copydata(m, off, sizeof(ip6e), (caddr_t)&ip6e);
1682 		if (nxtp)
1683 			*nxtp = ip6e.ip6e_nxt;
1684 		off += (ip6e.ip6e_len + 2) << 2;
1685 		return off;
1686 
1687 	case IPPROTO_HOPOPTS:
1688 	case IPPROTO_ROUTING:
1689 	case IPPROTO_DSTOPTS:
1690 		if (m->m_pkthdr.len < off + sizeof(ip6e))
1691 			return -1;
1692 		m_copydata(m, off, sizeof(ip6e), (caddr_t)&ip6e);
1693 		if (nxtp)
1694 			*nxtp = ip6e.ip6e_nxt;
1695 		off += (ip6e.ip6e_len + 1) << 3;
1696 		return off;
1697 
1698 	case IPPROTO_NONE:
1699 	case IPPROTO_ESP:
1700 	case IPPROTO_IPCOMP:
1701 		/* give up */
1702 		return -1;
1703 
1704 	default:
1705 		return -1;
1706 	}
1707 
1708 	/* NOTREACHED */
1709 }
1710 
1711 /*
1712  * get offset for the last header in the chain.  m will be kept untainted.
1713  */
1714 int
1715 ip6_lasthdr(const struct mbuf *m, int off, int proto, int *nxtp)
1716 {
1717 	int newoff;
1718 	int nxt;
1719 
1720 	if (!nxtp) {
1721 		nxt = -1;
1722 		nxtp = &nxt;
1723 	}
1724 	while (1) {
1725 		newoff = ip6_nexthdr(m, off, proto, nxtp);
1726 		if (newoff < 0)
1727 			return off;
1728 		else if (newoff < off)
1729 			return -1;	/* invalid */
1730 		else if (newoff == off)
1731 			return newoff;
1732 
1733 		off = newoff;
1734 		proto = *nxtp;
1735 	}
1736 }
1737 
1738 /*
1739  * System control for IP6
1740  */
1741 
1742 u_char	inet6ctlerrmap[PRC_NCMDS] = {
1743 	0,		0,		0,		0,
1744 	0,		EMSGSIZE,	EHOSTDOWN,	EHOSTUNREACH,
1745 	EHOSTUNREACH,	EHOSTUNREACH,	ECONNREFUSED,	ECONNREFUSED,
1746 	EMSGSIZE,	EHOSTUNREACH,	0,		0,
1747 	0,		0,		EHOSTUNREACH,	0,
1748 	ENOPROTOOPT,	ECONNREFUSED
1749 };
1750