xref: /netbsd-src/sys/netinet/ip_encap.c (revision 6a493d6bc668897c91594964a732d38505b70cbb)
1 /*	$KAME: ip_encap.c,v 1.73 2001/10/02 08:30:58 itojun Exp $	*/
2 
3 /*
4  * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
5  * All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  * 3. Neither the name of the project nor the names of its contributors
16  *    may be used to endorse or promote products derived from this software
17  *    without specific prior written permission.
18  *
19  * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29  * SUCH DAMAGE.
30  */
31 /*
32  * My grandfather said that there's a devil inside tunnelling technology...
33  *
34  * We have surprisingly many protocols that want packets with IP protocol
35  * #4 or #41.  Here's a list of protocols that want protocol #41:
36  *	RFC1933 configured tunnel
37  *	RFC1933 automatic tunnel
38  *	RFC2401 IPsec tunnel
39  *	RFC2473 IPv6 generic packet tunnelling
40  *	RFC2529 6over4 tunnel
41  *	RFC3056 6to4 tunnel
42  *	isatap tunnel
43  *	mobile-ip6 (uses RFC2473)
44  * Here's a list of protocol that want protocol #4:
45  *	RFC1853 IPv4-in-IPv4 tunnelling
46  *	RFC2003 IPv4 encapsulation within IPv4
47  *	RFC2344 reverse tunnelling for mobile-ip4
48  *	RFC2401 IPsec tunnel
49  * Well, what can I say.  They impose different en/decapsulation mechanism
50  * from each other, so they need separate protocol handler.  The only one
51  * we can easily determine by protocol # is IPsec, which always has
52  * AH/ESP/IPComp header right after outer IP header.
53  *
54  * So, clearly good old protosw does not work for protocol #4 and #41.
55  * The code will let you match protocol via src/dst address pair.
56  */
57 /* XXX is M_NETADDR correct? */
58 
59 /*
60  * With USE_RADIX the code will use radix table for tunnel lookup, for
61  * tunnels registered with encap_attach() with a addr/mask pair.
62  * Faster on machines with thousands of tunnel registerations (= interfaces).
63  *
64  * The code assumes that radix table code can handle non-continuous netmask,
65  * as it will pass radix table memory region with (src + dst) sockaddr pair.
66  *
67  * FreeBSD is excluded here as they make max_keylen a static variable, and
68  * thus forbid definition of radix table other than proper domains.
69  *
70  * !!!!!!!
71  * !!NOTE: dom_maxrtkey assumes USE_RADIX is defined.
72  * !!!!!!!
73  */
74 #define USE_RADIX
75 
76 #include <sys/cdefs.h>
77 __KERNEL_RCSID(0, "$NetBSD: ip_encap.c,v 1.39 2011/07/17 20:54:53 joerg Exp $");
78 
79 #include "opt_mrouting.h"
80 #include "opt_inet.h"
81 
82 #include <sys/param.h>
83 #include <sys/systm.h>
84 #include <sys/socket.h>
85 #include <sys/sockio.h>
86 #include <sys/mbuf.h>
87 #include <sys/errno.h>
88 #include <sys/protosw.h>
89 #include <sys/queue.h>
90 
91 #include <net/if.h>
92 #include <net/route.h>
93 
94 #include <netinet/in.h>
95 #include <netinet/in_systm.h>
96 #include <netinet/ip.h>
97 #include <netinet/ip_var.h>
98 #include <netinet/ip_encap.h>
99 #ifdef MROUTING
100 #include <netinet/ip_mroute.h>
101 #endif /* MROUTING */
102 
103 #ifdef INET6
104 #include <netinet/ip6.h>
105 #include <netinet6/ip6_var.h>
106 #include <netinet6/ip6protosw.h>
107 #include <netinet6/in6_var.h>
108 #include <netinet6/in6_pcb.h>
109 #include <netinet/icmp6.h>
110 #endif
111 
112 #include <net/net_osdep.h>
113 
114 enum direction { INBOUND, OUTBOUND };
115 
116 #ifdef INET
117 static struct encaptab *encap4_lookup(struct mbuf *, int, int, enum direction);
118 #endif
119 #ifdef INET6
120 static struct encaptab *encap6_lookup(struct mbuf *, int, int, enum direction);
121 #endif
122 static int encap_add(struct encaptab *);
123 static int encap_remove(struct encaptab *);
124 static int encap_afcheck(int, const struct sockaddr *, const struct sockaddr *);
125 #ifdef USE_RADIX
126 static struct radix_node_head *encap_rnh(int);
127 static int mask_matchlen(const struct sockaddr *);
128 #endif
129 #ifndef USE_RADIX
130 static int mask_match(const struct encaptab *, const struct sockaddr *,
131 		const struct sockaddr *);
132 #endif
133 static void encap_fillarg(struct mbuf *, const struct encaptab *);
134 
135 LIST_HEAD(, encaptab) encaptab = LIST_HEAD_INITIALIZER(&encaptab);
136 
137 #ifdef USE_RADIX
138 extern int max_keylen;	/* radix.c */
139 struct radix_node_head *encap_head[2];	/* 0 for AF_INET, 1 for AF_INET6 */
140 #endif
141 
142 void
143 encap_init(void)
144 {
145 	static int initialized = 0;
146 
147 	if (initialized)
148 		return;
149 	initialized++;
150 #if 0
151 	/*
152 	 * we cannot use LIST_INIT() here, since drivers may want to call
153 	 * encap_attach(), on driver attach.  encap_init() will be called
154 	 * on AF_INET{,6} initialization, which happens after driver
155 	 * initialization - using LIST_INIT() here can nuke encap_attach()
156 	 * from drivers.
157 	 */
158 	LIST_INIT(&encaptab);
159 #endif
160 
161 #ifdef USE_RADIX
162 	/*
163 	 * initialize radix lookup table when the radix subsystem is inited.
164 	 */
165 	rn_delayedinit((void *)&encap_head[0],
166 	    sizeof(struct sockaddr_pack) << 3);
167 #ifdef INET6
168 	rn_delayedinit((void *)&encap_head[1],
169 	    sizeof(struct sockaddr_pack) << 3);
170 #endif
171 #endif
172 }
173 
174 #ifdef INET
175 static struct encaptab *
176 encap4_lookup(struct mbuf *m, int off, int proto, enum direction dir)
177 {
178 	struct ip *ip;
179 	struct ip_pack4 pack;
180 	struct encaptab *ep, *match;
181 	int prio, matchprio;
182 #ifdef USE_RADIX
183 	struct radix_node_head *rnh = encap_rnh(AF_INET);
184 	struct radix_node *rn;
185 #endif
186 
187 #ifdef DIAGNOSTIC
188 	if (m->m_len < sizeof(*ip))
189 		panic("encap4_lookup");
190 #endif
191 	ip = mtod(m, struct ip *);
192 
193 	memset(&pack, 0, sizeof(pack));
194 	pack.p.sp_len = sizeof(pack);
195 	pack.mine.sin_family = pack.yours.sin_family = AF_INET;
196 	pack.mine.sin_len = pack.yours.sin_len = sizeof(struct sockaddr_in);
197 	if (dir == INBOUND) {
198 		pack.mine.sin_addr = ip->ip_dst;
199 		pack.yours.sin_addr = ip->ip_src;
200 	} else {
201 		pack.mine.sin_addr = ip->ip_src;
202 		pack.yours.sin_addr = ip->ip_dst;
203 	}
204 
205 	match = NULL;
206 	matchprio = 0;
207 
208 #ifdef USE_RADIX
209 	rn = rnh->rnh_matchaddr((void *)&pack, rnh);
210 	if (rn && (rn->rn_flags & RNF_ROOT) == 0) {
211 		match = (struct encaptab *)rn;
212 		matchprio = mask_matchlen(match->srcmask) +
213 		    mask_matchlen(match->dstmask);
214 	}
215 #endif
216 
217 	LIST_FOREACH(ep, &encaptab, chain) {
218 		if (ep->af != AF_INET)
219 			continue;
220 		if (ep->proto >= 0 && ep->proto != proto)
221 			continue;
222 		if (ep->func)
223 			prio = (*ep->func)(m, off, proto, ep->arg);
224 		else {
225 #ifdef USE_RADIX
226 			continue;
227 #else
228 			prio = mask_match(ep, (struct sockaddr *)&pack.mine,
229 			    (struct sockaddr *)&pack.yours);
230 #endif
231 		}
232 
233 		/*
234 		 * We prioritize the matches by using bit length of the
235 		 * matches.  mask_match() and user-supplied matching function
236 		 * should return the bit length of the matches (for example,
237 		 * if both src/dst are matched for IPv4, 64 should be returned).
238 		 * 0 or negative return value means "it did not match".
239 		 *
240 		 * The question is, since we have two "mask" portion, we
241 		 * cannot really define total order between entries.
242 		 * For example, which of these should be preferred?
243 		 * mask_match() returns 48 (32 + 16) for both of them.
244 		 *	src=3ffe::/16, dst=3ffe:501::/32
245 		 *	src=3ffe:501::/32, dst=3ffe::/16
246 		 *
247 		 * We need to loop through all the possible candidates
248 		 * to get the best match - the search takes O(n) for
249 		 * n attachments (i.e. interfaces).
250 		 *
251 		 * For radix-based lookup, I guess source takes precedence.
252 		 * See rn_{refines,lexobetter} for the correct answer.
253 		 */
254 		if (prio <= 0)
255 			continue;
256 		if (prio > matchprio) {
257 			matchprio = prio;
258 			match = ep;
259 		}
260 	}
261 
262 	return match;
263 #undef s
264 #undef d
265 }
266 
267 void
268 encap4_input(struct mbuf *m, ...)
269 {
270 	int off, proto;
271 	va_list ap;
272 	const struct protosw *psw;
273 	struct encaptab *match;
274 
275 	va_start(ap, m);
276 	off = va_arg(ap, int);
277 	proto = va_arg(ap, int);
278 	va_end(ap);
279 
280 	match = encap4_lookup(m, off, proto, INBOUND);
281 
282 	if (match) {
283 		/* found a match, "match" has the best one */
284 		psw = match->psw;
285 		if (psw && psw->pr_input) {
286 			encap_fillarg(m, match);
287 			(*psw->pr_input)(m, off, proto);
288 		} else
289 			m_freem(m);
290 		return;
291 	}
292 
293 	/* last resort: inject to raw socket */
294 	rip_input(m, off, proto);
295 }
296 #endif
297 
298 #ifdef INET6
299 static struct encaptab *
300 encap6_lookup(struct mbuf *m, int off, int proto, enum direction dir)
301 {
302 	struct ip6_hdr *ip6;
303 	struct ip_pack6 pack;
304 	int prio, matchprio;
305 	struct encaptab *ep, *match;
306 #ifdef USE_RADIX
307 	struct radix_node_head *rnh = encap_rnh(AF_INET6);
308 	struct radix_node *rn;
309 #endif
310 
311 #ifdef DIAGNOSTIC
312 	if (m->m_len < sizeof(*ip6))
313 		panic("encap6_lookup");
314 #endif
315 	ip6 = mtod(m, struct ip6_hdr *);
316 
317 	memset(&pack, 0, sizeof(pack));
318 	pack.p.sp_len = sizeof(pack);
319 	pack.mine.sin6_family = pack.yours.sin6_family = AF_INET6;
320 	pack.mine.sin6_len = pack.yours.sin6_len = sizeof(struct sockaddr_in6);
321 	if (dir == INBOUND) {
322 		pack.mine.sin6_addr = ip6->ip6_dst;
323 		pack.yours.sin6_addr = ip6->ip6_src;
324 	} else {
325 		pack.mine.sin6_addr = ip6->ip6_src;
326 		pack.yours.sin6_addr = ip6->ip6_dst;
327 	}
328 
329 	match = NULL;
330 	matchprio = 0;
331 
332 #ifdef USE_RADIX
333 	rn = rnh->rnh_matchaddr((void *)&pack, rnh);
334 	if (rn && (rn->rn_flags & RNF_ROOT) == 0) {
335 		match = (struct encaptab *)rn;
336 		matchprio = mask_matchlen(match->srcmask) +
337 		    mask_matchlen(match->dstmask);
338 	}
339 #endif
340 
341 	LIST_FOREACH(ep, &encaptab, chain) {
342 		if (ep->af != AF_INET6)
343 			continue;
344 		if (ep->proto >= 0 && ep->proto != proto)
345 			continue;
346 		if (ep->func)
347 			prio = (*ep->func)(m, off, proto, ep->arg);
348 		else {
349 #ifdef USE_RADIX
350 			continue;
351 #else
352 			prio = mask_match(ep, (struct sockaddr *)&pack.mine,
353 			    (struct sockaddr *)&pack.yours);
354 #endif
355 		}
356 
357 		/* see encap4_lookup() for issues here */
358 		if (prio <= 0)
359 			continue;
360 		if (prio > matchprio) {
361 			matchprio = prio;
362 			match = ep;
363 		}
364 	}
365 
366 	return match;
367 #undef s
368 #undef d
369 }
370 
371 int
372 encap6_input(struct mbuf **mp, int *offp, int proto)
373 {
374 	struct mbuf *m = *mp;
375 	const struct ip6protosw *psw;
376 	struct encaptab *match;
377 
378 	match = encap6_lookup(m, *offp, proto, INBOUND);
379 
380 	if (match) {
381 		/* found a match */
382 		psw = (const struct ip6protosw *)match->psw;
383 		if (psw && psw->pr_input) {
384 			encap_fillarg(m, match);
385 			return (*psw->pr_input)(mp, offp, proto);
386 		} else {
387 			m_freem(m);
388 			return IPPROTO_DONE;
389 		}
390 	}
391 
392 	/* last resort: inject to raw socket */
393 	return rip6_input(mp, offp, proto);
394 }
395 #endif
396 
397 static int
398 encap_add(struct encaptab *ep)
399 {
400 #ifdef USE_RADIX
401 	struct radix_node_head *rnh = encap_rnh(ep->af);
402 #endif
403 	int error = 0;
404 
405 	LIST_INSERT_HEAD(&encaptab, ep, chain);
406 #ifdef USE_RADIX
407 	if (!ep->func && rnh) {
408 		if (!rnh->rnh_addaddr((void *)ep->addrpack,
409 		    (void *)ep->maskpack, rnh, ep->nodes)) {
410 			error = EEXIST;
411 			goto fail;
412 		}
413 	}
414 #endif
415 	return error;
416 
417  fail:
418 	LIST_REMOVE(ep, chain);
419 	return error;
420 }
421 
422 static int
423 encap_remove(struct encaptab *ep)
424 {
425 #ifdef USE_RADIX
426 	struct radix_node_head *rnh = encap_rnh(ep->af);
427 #endif
428 	int error = 0;
429 
430 	LIST_REMOVE(ep, chain);
431 #ifdef USE_RADIX
432 	if (!ep->func && rnh) {
433 		if (!rnh->rnh_deladdr((void *)ep->addrpack,
434 		    (void *)ep->maskpack, rnh))
435 			error = ESRCH;
436 	}
437 #endif
438 	return error;
439 }
440 
441 static int
442 encap_afcheck(int af, const struct sockaddr *sp, const struct sockaddr *dp)
443 {
444 	if (sp && dp) {
445 		if (sp->sa_len != dp->sa_len)
446 			return EINVAL;
447 		if (af != sp->sa_family || af != dp->sa_family)
448 			return EINVAL;
449 	} else if (!sp && !dp)
450 		;
451 	else
452 		return EINVAL;
453 
454 	switch (af) {
455 	case AF_INET:
456 		if (sp && sp->sa_len != sizeof(struct sockaddr_in))
457 			return EINVAL;
458 		if (dp && dp->sa_len != sizeof(struct sockaddr_in))
459 			return EINVAL;
460 		break;
461 #ifdef INET6
462 	case AF_INET6:
463 		if (sp && sp->sa_len != sizeof(struct sockaddr_in6))
464 			return EINVAL;
465 		if (dp && dp->sa_len != sizeof(struct sockaddr_in6))
466 			return EINVAL;
467 		break;
468 #endif
469 	default:
470 		return EAFNOSUPPORT;
471 	}
472 
473 	return 0;
474 }
475 
476 /*
477  * sp (src ptr) is always my side, and dp (dst ptr) is always remote side.
478  * length of mask (sm and dm) is assumed to be same as sp/dp.
479  * Return value will be necessary as input (cookie) for encap_detach().
480  */
481 const struct encaptab *
482 encap_attach(int af, int proto,
483     const struct sockaddr *sp, const struct sockaddr *sm,
484     const struct sockaddr *dp, const struct sockaddr *dm,
485     const struct protosw *psw, void *arg)
486 {
487 	struct encaptab *ep;
488 	int error;
489 	int s;
490 	size_t l;
491 	struct ip_pack4 *pack4;
492 #ifdef INET6
493 	struct ip_pack6 *pack6;
494 #endif
495 
496 	s = splsoftnet();
497 	/* sanity check on args */
498 	error = encap_afcheck(af, sp, dp);
499 	if (error)
500 		goto fail;
501 
502 	/* check if anyone have already attached with exactly same config */
503 	LIST_FOREACH(ep, &encaptab, chain) {
504 		if (ep->af != af)
505 			continue;
506 		if (ep->proto != proto)
507 			continue;
508 		if (ep->func)
509 			continue;
510 #ifdef DIAGNOSTIC
511 		if (!ep->src || !ep->dst || !ep->srcmask || !ep->dstmask)
512 			panic("null pointers in encaptab");
513 #endif
514 		if (ep->src->sa_len != sp->sa_len ||
515 		    memcmp(ep->src, sp, sp->sa_len) != 0 ||
516 		    memcmp(ep->srcmask, sm, sp->sa_len) != 0)
517 			continue;
518 		if (ep->dst->sa_len != dp->sa_len ||
519 		    memcmp(ep->dst, dp, dp->sa_len) != 0 ||
520 		    memcmp(ep->dstmask, dm, dp->sa_len) != 0)
521 			continue;
522 
523 		error = EEXIST;
524 		goto fail;
525 	}
526 
527 	switch (af) {
528 	case AF_INET:
529 		l = sizeof(*pack4);
530 		break;
531 #ifdef INET6
532 	case AF_INET6:
533 		l = sizeof(*pack6);
534 		break;
535 #endif
536 	default:
537 		goto fail;
538 	}
539 
540 	/* M_NETADDR ok? */
541 	ep = malloc(sizeof(*ep), M_NETADDR, M_NOWAIT|M_ZERO);
542 	if (ep == NULL) {
543 		error = ENOBUFS;
544 		goto fail;
545 	}
546 	ep->addrpack = malloc(l, M_NETADDR, M_NOWAIT|M_ZERO);
547 	if (ep->addrpack == NULL) {
548 		error = ENOBUFS;
549 		goto gc;
550 	}
551 	ep->maskpack = malloc(l, M_NETADDR, M_NOWAIT|M_ZERO);
552 	if (ep->maskpack == NULL) {
553 		error = ENOBUFS;
554 		goto gc;
555 	}
556 
557 	ep->af = af;
558 	ep->proto = proto;
559 	ep->addrpack->sa_len = l & 0xff;
560 	ep->maskpack->sa_len = l & 0xff;
561 	switch (af) {
562 	case AF_INET:
563 		pack4 = (struct ip_pack4 *)ep->addrpack;
564 		ep->src = (struct sockaddr *)&pack4->mine;
565 		ep->dst = (struct sockaddr *)&pack4->yours;
566 		pack4 = (struct ip_pack4 *)ep->maskpack;
567 		ep->srcmask = (struct sockaddr *)&pack4->mine;
568 		ep->dstmask = (struct sockaddr *)&pack4->yours;
569 		break;
570 #ifdef INET6
571 	case AF_INET6:
572 		pack6 = (struct ip_pack6 *)ep->addrpack;
573 		ep->src = (struct sockaddr *)&pack6->mine;
574 		ep->dst = (struct sockaddr *)&pack6->yours;
575 		pack6 = (struct ip_pack6 *)ep->maskpack;
576 		ep->srcmask = (struct sockaddr *)&pack6->mine;
577 		ep->dstmask = (struct sockaddr *)&pack6->yours;
578 		break;
579 #endif
580 	}
581 
582 	memcpy(ep->src, sp, sp->sa_len);
583 	memcpy(ep->srcmask, sm, sp->sa_len);
584 	memcpy(ep->dst, dp, dp->sa_len);
585 	memcpy(ep->dstmask, dm, dp->sa_len);
586 	ep->psw = psw;
587 	ep->arg = arg;
588 
589 	error = encap_add(ep);
590 	if (error)
591 		goto gc;
592 
593 	error = 0;
594 	splx(s);
595 	return ep;
596 
597 gc:
598 	if (ep->addrpack)
599 		free(ep->addrpack, M_NETADDR);
600 	if (ep->maskpack)
601 		free(ep->maskpack, M_NETADDR);
602 	if (ep)
603 		free(ep, M_NETADDR);
604 fail:
605 	splx(s);
606 	return NULL;
607 }
608 
609 const struct encaptab *
610 encap_attach_func(int af, int proto,
611     int (*func)(struct mbuf *, int, int, void *),
612     const struct protosw *psw, void *arg)
613 {
614 	struct encaptab *ep;
615 	int error;
616 	int s;
617 
618 	s = splsoftnet();
619 	/* sanity check on args */
620 	if (!func) {
621 		error = EINVAL;
622 		goto fail;
623 	}
624 
625 	error = encap_afcheck(af, NULL, NULL);
626 	if (error)
627 		goto fail;
628 
629 	ep = malloc(sizeof(*ep), M_NETADDR, M_NOWAIT);	/*XXX*/
630 	if (ep == NULL) {
631 		error = ENOBUFS;
632 		goto fail;
633 	}
634 	memset(ep, 0, sizeof(*ep));
635 
636 	ep->af = af;
637 	ep->proto = proto;
638 	ep->func = func;
639 	ep->psw = psw;
640 	ep->arg = arg;
641 
642 	error = encap_add(ep);
643 	if (error)
644 		goto fail;
645 
646 	error = 0;
647 	splx(s);
648 	return ep;
649 
650 fail:
651 	splx(s);
652 	return NULL;
653 }
654 
655 /* XXX encap4_ctlinput() is necessary if we set DF=1 on outer IPv4 header */
656 
657 #ifdef INET6
658 void *
659 encap6_ctlinput(int cmd, const struct sockaddr *sa, void *d0)
660 {
661 	void *d = d0;
662 	struct ip6_hdr *ip6;
663 	struct mbuf *m;
664 	int off;
665 	struct ip6ctlparam *ip6cp = NULL;
666 	int nxt;
667 	struct encaptab *ep;
668 	const struct ip6protosw *psw;
669 
670 	if (sa->sa_family != AF_INET6 ||
671 	    sa->sa_len != sizeof(struct sockaddr_in6))
672 		return NULL;
673 
674 	if ((unsigned)cmd >= PRC_NCMDS)
675 		return NULL;
676 	if (cmd == PRC_HOSTDEAD)
677 		d = NULL;
678 	else if (cmd == PRC_MSGSIZE)
679 		; /* special code is present, see below */
680 	else if (inet6ctlerrmap[cmd] == 0)
681 		return NULL;
682 
683 	/* if the parameter is from icmp6, decode it. */
684 	if (d != NULL) {
685 		ip6cp = (struct ip6ctlparam *)d;
686 		m = ip6cp->ip6c_m;
687 		ip6 = ip6cp->ip6c_ip6;
688 		off = ip6cp->ip6c_off;
689 		nxt = ip6cp->ip6c_nxt;
690 
691 		if (ip6 && cmd == PRC_MSGSIZE) {
692 			int valid = 0;
693 			struct encaptab *match;
694 
695 			/*
696 		 	* Check to see if we have a valid encap configuration.
697 		 	*/
698 			match = encap6_lookup(m, off, nxt, OUTBOUND);
699 			if (match)
700 				valid++;
701 
702 			/*
703 		 	* Depending on the value of "valid" and routing table
704 		 	* size (mtudisc_{hi,lo}wat), we will:
705 		 	* - recalcurate the new MTU and create the
706 		 	*   corresponding routing entry, or
707 		 	* - ignore the MTU change notification.
708 		 	*/
709 			icmp6_mtudisc_update((struct ip6ctlparam *)d, valid);
710 		}
711 	} else {
712 		m = NULL;
713 		ip6 = NULL;
714 		nxt = -1;
715 	}
716 
717 	/* inform all listeners */
718 	LIST_FOREACH(ep, &encaptab, chain) {
719 		if (ep->af != AF_INET6)
720 			continue;
721 		if (ep->proto >= 0 && ep->proto != nxt)
722 			continue;
723 
724 		/* should optimize by looking at address pairs */
725 
726 		/* XXX need to pass ep->arg or ep itself to listeners */
727 		psw = (const struct ip6protosw *)ep->psw;
728 		if (psw && psw->pr_ctlinput)
729 			(*psw->pr_ctlinput)(cmd, sa, d);
730 	}
731 
732 	rip6_ctlinput(cmd, sa, d0);
733 	return NULL;
734 }
735 #endif
736 
737 int
738 encap_detach(const struct encaptab *cookie)
739 {
740 	const struct encaptab *ep = cookie;
741 	struct encaptab *p;
742 	int error;
743 
744 	LIST_FOREACH(p, &encaptab, chain) {
745 		if (p == ep) {
746 			error = encap_remove(p);
747 			if (error)
748 				return error;
749 			if (!ep->func) {
750 				free(p->addrpack, M_NETADDR);
751 				free(p->maskpack, M_NETADDR);
752 			}
753 			free(p, M_NETADDR);	/*XXX*/
754 			return 0;
755 		}
756 	}
757 
758 	return ENOENT;
759 }
760 
761 #ifdef USE_RADIX
762 static struct radix_node_head *
763 encap_rnh(int af)
764 {
765 
766 	switch (af) {
767 	case AF_INET:
768 		return encap_head[0];
769 #ifdef INET6
770 	case AF_INET6:
771 		return encap_head[1];
772 #endif
773 	default:
774 		return NULL;
775 	}
776 }
777 
778 static int
779 mask_matchlen(const struct sockaddr *sa)
780 {
781 	const char *p, *ep;
782 	int l;
783 
784 	p = (const char *)sa;
785 	ep = p + sa->sa_len;
786 	p += 2;	/* sa_len + sa_family */
787 
788 	l = 0;
789 	while (p < ep) {
790 		l += (*p ? 8 : 0);	/* estimate */
791 		p++;
792 	}
793 	return l;
794 }
795 #endif
796 
797 #ifndef USE_RADIX
798 static int
799 mask_match(const struct encaptab *ep,
800 	   const struct sockaddr *sp,
801 	   const struct sockaddr *dp)
802 {
803 	struct sockaddr_storage s;
804 	struct sockaddr_storage d;
805 	int i;
806 	const u_int8_t *p, *q;
807 	u_int8_t *r;
808 	int matchlen;
809 
810 #ifdef DIAGNOSTIC
811 	if (ep->func)
812 		panic("wrong encaptab passed to mask_match");
813 #endif
814 	if (sp->sa_len > sizeof(s) || dp->sa_len > sizeof(d))
815 		return 0;
816 	if (sp->sa_family != ep->af || dp->sa_family != ep->af)
817 		return 0;
818 	if (sp->sa_len != ep->src->sa_len || dp->sa_len != ep->dst->sa_len)
819 		return 0;
820 
821 	matchlen = 0;
822 
823 	p = (const u_int8_t *)sp;
824 	q = (const u_int8_t *)ep->srcmask;
825 	r = (u_int8_t *)&s;
826 	for (i = 0 ; i < sp->sa_len; i++) {
827 		r[i] = p[i] & q[i];
828 		/* XXX estimate */
829 		matchlen += (q[i] ? 8 : 0);
830 	}
831 
832 	p = (const u_int8_t *)dp;
833 	q = (const u_int8_t *)ep->dstmask;
834 	r = (u_int8_t *)&d;
835 	for (i = 0 ; i < dp->sa_len; i++) {
836 		r[i] = p[i] & q[i];
837 		/* XXX rough estimate */
838 		matchlen += (q[i] ? 8 : 0);
839 	}
840 
841 	/* need to overwrite len/family portion as we don't compare them */
842 	s.ss_len = sp->sa_len;
843 	s.ss_family = sp->sa_family;
844 	d.ss_len = dp->sa_len;
845 	d.ss_family = dp->sa_family;
846 
847 	if (memcmp(&s, ep->src, ep->src->sa_len) == 0 &&
848 	    memcmp(&d, ep->dst, ep->dst->sa_len) == 0) {
849 		return matchlen;
850 	} else
851 		return 0;
852 }
853 #endif
854 
855 static void
856 encap_fillarg(struct mbuf *m, const struct encaptab *ep)
857 {
858 	struct m_tag *mtag;
859 
860 	mtag = m_tag_get(PACKET_TAG_ENCAP, sizeof(void *), M_NOWAIT);
861 	if (mtag) {
862 		*(void **)(mtag + 1) = ep->arg;
863 		m_tag_prepend(m, mtag);
864 	}
865 }
866 
867 void *
868 encap_getarg(struct mbuf *m)
869 {
870 	void *p;
871 	struct m_tag *mtag;
872 
873 	p = NULL;
874 	mtag = m_tag_find(m, PACKET_TAG_ENCAP, NULL);
875 	if (mtag != NULL) {
876 		p = *(void **)(mtag + 1);
877 		m_tag_delete(m, mtag);
878 	}
879 	return p;
880 }
881