xref: /netbsd/sys/netinet6/in6_ifattach.c (revision c4a72b64)
1 /*	$NetBSD: in6_ifattach.c,v 1.54 2002/11/02 07:30:55 perry Exp $	*/
2 /*	$KAME: in6_ifattach.c,v 1.124 2001/07/18 08:32:51 jinmei Exp $	*/
3 
4 /*
5  * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
6  * All rights reserved.
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions
10  * are met:
11  * 1. Redistributions of source code must retain the above copyright
12  *    notice, this list of conditions and the following disclaimer.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in the
15  *    documentation and/or other materials provided with the distribution.
16  * 3. Neither the name of the project nor the names of its contributors
17  *    may be used to endorse or promote products derived from this software
18  *    without specific prior written permission.
19  *
20  * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30  * SUCH DAMAGE.
31  */
32 
33 #include <sys/cdefs.h>
34 __KERNEL_RCSID(0, "$NetBSD: in6_ifattach.c,v 1.54 2002/11/02 07:30:55 perry Exp $");
35 
36 #include <sys/param.h>
37 #include <sys/systm.h>
38 #include <sys/malloc.h>
39 #include <sys/socket.h>
40 #include <sys/sockio.h>
41 #include <sys/kernel.h>
42 #include <sys/syslog.h>
43 #include <sys/md5.h>
44 
45 #include <net/if.h>
46 #include <net/if_dl.h>
47 #include <net/if_types.h>
48 #include <net/route.h>
49 
50 #include <netinet/in.h>
51 #include <netinet/in_var.h>
52 
53 #include <netinet/ip6.h>
54 #include <netinet6/ip6_var.h>
55 #include <netinet6/in6_ifattach.h>
56 #include <netinet6/ip6_var.h>
57 #include <netinet6/nd6.h>
58 
59 #include <net/net_osdep.h>
60 
61 unsigned long in6_maxmtu = 0;
62 
63 int ip6_auto_linklocal = 1;	/* enable by default */
64 
65 static int get_rand_ifid __P((struct ifnet *, struct in6_addr *));
66 static int get_hw_ifid __P((struct ifnet *, struct in6_addr *));
67 static int get_ifid __P((struct ifnet *, struct ifnet *, struct in6_addr *));
68 static int in6_ifattach_linklocal __P((struct ifnet *, struct ifnet *));
69 static int in6_ifattach_loopback __P((struct ifnet *));
70 
71 #define EUI64_GBIT	0x01
72 #define EUI64_UBIT	0x02
73 #define EUI64_TO_IFID(in6)	do {(in6)->s6_addr[8] ^= EUI64_UBIT; } while (/*CONSTCOND*/ 0)
74 #define EUI64_GROUP(in6)	((in6)->s6_addr[8] & EUI64_GBIT)
75 #define EUI64_INDIVIDUAL(in6)	(!EUI64_GROUP(in6))
76 #define EUI64_LOCAL(in6)	((in6)->s6_addr[8] & EUI64_UBIT)
77 #define EUI64_UNIVERSAL(in6)	(!EUI64_LOCAL(in6))
78 
79 #define IFID_LOCAL(in6)		(!EUI64_LOCAL(in6))
80 #define IFID_UNIVERSAL(in6)	(!EUI64_UNIVERSAL(in6))
81 
82 /*
83  * Generate a last-resort interface identifier, when the machine has no
84  * IEEE802/EUI64 address sources.
85  * The goal here is to get an interface identifier that is
86  * (1) random enough and (2) does not change across reboot.
87  * We currently use MD5(hostname) for it.
88  */
89 static int
90 get_rand_ifid(ifp, in6)
91 	struct ifnet *ifp;
92 	struct in6_addr *in6;	/* upper 64bits are preserved */
93 {
94 	MD5_CTX ctxt;
95 	u_int8_t digest[16];
96 
97 #if 0
98 	/* we need at least several letters as seed for ifid */
99 	if (hostnamelen < 3)
100 		return -1;
101 #endif
102 
103 	/* generate 8 bytes of pseudo-random value. */
104 	bzero(&ctxt, sizeof(ctxt));
105 	MD5Init(&ctxt);
106 	MD5Update(&ctxt, (u_char *)hostname, hostnamelen);
107 	MD5Final(digest, &ctxt);
108 
109 	/* assumes sizeof(digest) > sizeof(ifid) */
110 	bcopy(digest, &in6->s6_addr[8], 8);
111 
112 	/* make sure to set "u" bit to local, and "g" bit to individual. */
113 	in6->s6_addr[8] &= ~EUI64_GBIT;	/* g bit to "individual" */
114 	in6->s6_addr[8] |= EUI64_UBIT;	/* u bit to "local" */
115 
116 	/* convert EUI64 into IPv6 interface identifier */
117 	EUI64_TO_IFID(in6);
118 
119 	return 0;
120 }
121 
122 /*
123  * Get interface identifier for the specified interface.
124  * XXX assumes single sockaddr_dl (AF_LINK address) per an interface
125  */
126 static int
127 get_hw_ifid(ifp, in6)
128 	struct ifnet *ifp;
129 	struct in6_addr *in6;	/* upper 64bits are preserved */
130 {
131 	struct ifaddr *ifa;
132 	struct sockaddr_dl *sdl;
133 	char *addr;
134 	size_t addrlen;
135 	static u_int8_t allzero[8] = { 0, 0, 0, 0, 0, 0, 0, 0 };
136 	static u_int8_t allone[8] =
137 		{ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
138 
139 	for (ifa = ifp->if_addrlist.tqh_first;
140 	     ifa;
141 	     ifa = ifa->ifa_list.tqe_next)
142 	{
143 		if (ifa->ifa_addr->sa_family != AF_LINK)
144 			continue;
145 		sdl = (struct sockaddr_dl *)ifa->ifa_addr;
146 		if (sdl == NULL)
147 			continue;
148 		if (sdl->sdl_alen == 0)
149 			continue;
150 
151 		goto found;
152 	}
153 
154 	return -1;
155 
156 found:
157 	addr = LLADDR(sdl);
158 	addrlen = sdl->sdl_alen;
159 
160 	switch (ifp->if_type) {
161 	case IFT_IEEE1394:
162 	case IFT_IEEE80211:
163 		/* IEEE1394 uses 16byte length address starting with EUI64 */
164 		if (addrlen > 8)
165 			addrlen = 8;
166 		break;
167 	default:
168 		break;
169 	}
170 
171 	/* get EUI64 */
172 	switch (ifp->if_type) {
173 	/* IEEE802/EUI64 cases - what others? */
174 	case IFT_ETHER:
175 	case IFT_FDDI:
176 	case IFT_ATM:
177 	case IFT_IEEE1394:
178 	case IFT_IEEE80211:
179 		/* look at IEEE802/EUI64 only */
180 		if (addrlen != 8 && addrlen != 6)
181 			return -1;
182 
183 		/*
184 		 * check for invalid MAC address - on bsdi, we see it a lot
185 		 * since wildboar configures all-zero MAC on pccard before
186 		 * card insertion.
187 		 */
188 		if (bcmp(addr, allzero, addrlen) == 0)
189 			return -1;
190 		if (bcmp(addr, allone, addrlen) == 0)
191 			return -1;
192 
193 		/* make EUI64 address */
194 		if (addrlen == 8)
195 			bcopy(addr, &in6->s6_addr[8], 8);
196 		else if (addrlen == 6) {
197 			in6->s6_addr[8] = addr[0];
198 			in6->s6_addr[9] = addr[1];
199 			in6->s6_addr[10] = addr[2];
200 			in6->s6_addr[11] = 0xff;
201 			in6->s6_addr[12] = 0xfe;
202 			in6->s6_addr[13] = addr[3];
203 			in6->s6_addr[14] = addr[4];
204 			in6->s6_addr[15] = addr[5];
205 		}
206 		break;
207 
208 	case IFT_ARCNET:
209 		if (addrlen != 1)
210 			return -1;
211 		if (!addr[0])
212 			return -1;
213 
214 		bzero(&in6->s6_addr[8], 8);
215 		in6->s6_addr[15] = addr[0];
216 
217 		/*
218 		 * due to insufficient bitwidth, we mark it local.
219 		 */
220 		in6->s6_addr[8] &= ~EUI64_GBIT;	/* g bit to "individual" */
221 		in6->s6_addr[8] |= EUI64_UBIT;	/* u bit to "local" */
222 		break;
223 
224 	case IFT_GIF:
225 #ifdef IFT_STF
226 	case IFT_STF:
227 #endif
228 		/*
229 		 * RFC2893 says: "SHOULD use IPv4 address as ifid source".
230 		 * however, IPv4 address is not very suitable as unique
231 		 * identifier source (can be renumbered).
232 		 * we don't do this.
233 		 */
234 		return -1;
235 
236 	default:
237 		return -1;
238 	}
239 
240 	/* sanity check: g bit must not indicate "group" */
241 	if (EUI64_GROUP(in6))
242 		return -1;
243 
244 	/* convert EUI64 into IPv6 interface identifier */
245 	EUI64_TO_IFID(in6);
246 
247 	/*
248 	 * sanity check: ifid must not be all zero, avoid conflict with
249 	 * subnet router anycast
250 	 */
251 	if ((in6->s6_addr[8] & ~(EUI64_GBIT | EUI64_UBIT)) == 0x00 &&
252 	    bcmp(&in6->s6_addr[9], allzero, 7) == 0) {
253 		return -1;
254 	}
255 
256 	return 0;
257 }
258 
259 /*
260  * Get interface identifier for the specified interface.  If it is not
261  * available on ifp0, borrow interface identifier from other information
262  * sources.
263  */
264 static int
265 get_ifid(ifp0, altifp, in6)
266 	struct ifnet *ifp0;
267 	struct ifnet *altifp;	/*secondary EUI64 source*/
268 	struct in6_addr *in6;
269 {
270 	struct ifnet *ifp;
271 
272 	/* first, try to get it from the interface itself */
273 	if (get_hw_ifid(ifp0, in6) == 0) {
274 		nd6log((LOG_DEBUG, "%s: got interface identifier from itself\n",
275 		    if_name(ifp0)));
276 		goto success;
277 	}
278 
279 	/* try secondary EUI64 source. this basically is for ATM PVC */
280 	if (altifp && get_hw_ifid(altifp, in6) == 0) {
281 		nd6log((LOG_DEBUG, "%s: got interface identifier from %s\n",
282 		    if_name(ifp0), if_name(altifp)));
283 		goto success;
284 	}
285 
286 	/* next, try to get it from some other hardware interface */
287 	for (ifp = ifnet.tqh_first; ifp; ifp = ifp->if_list.tqe_next)
288 	{
289 		if (ifp == ifp0)
290 			continue;
291 		if (get_hw_ifid(ifp, in6) != 0)
292 			continue;
293 
294 		/*
295 		 * to borrow ifid from other interface, ifid needs to be
296 		 * globally unique
297 		 */
298 		if (IFID_UNIVERSAL(in6)) {
299 			nd6log((LOG_DEBUG,
300 			    "%s: borrow interface identifier from %s\n",
301 			    if_name(ifp0), if_name(ifp)));
302 			goto success;
303 		}
304 	}
305 
306 	/* last resort: get from random number source */
307 	if (get_rand_ifid(ifp, in6) == 0) {
308 		nd6log((LOG_DEBUG,
309 		    "%s: interface identifier generated by random number\n",
310 		    if_name(ifp0)));
311 		goto success;
312 	}
313 
314 	printf("%s: failed to get interface identifier\n", if_name(ifp0));
315 	return -1;
316 
317 success:
318 	nd6log((LOG_INFO, "%s: ifid: %02x:%02x:%02x:%02x:%02x:%02x:%02x:%02x\n",
319 	    if_name(ifp0), in6->s6_addr[8], in6->s6_addr[9], in6->s6_addr[10],
320 	    in6->s6_addr[11], in6->s6_addr[12], in6->s6_addr[13],
321 	    in6->s6_addr[14], in6->s6_addr[15]));
322 	return 0;
323 }
324 
325 static int
326 in6_ifattach_linklocal(ifp, altifp)
327 	struct ifnet *ifp;
328 	struct ifnet *altifp;	/*secondary EUI64 source*/
329 {
330 	struct in6_ifaddr *ia;
331 	struct in6_aliasreq ifra;
332 	struct nd_prefix pr0;
333 	int i, error;
334 
335 	/*
336 	 * configure link-local address.
337 	 */
338 	bzero(&ifra, sizeof(ifra));
339 
340 	/*
341 	 * in6_update_ifa() does not use ifra_name, but we accurately set it
342 	 * for safety.
343 	 */
344 	strncpy(ifra.ifra_name, if_name(ifp), sizeof(ifra.ifra_name));
345 
346 	ifra.ifra_addr.sin6_family = AF_INET6;
347 	ifra.ifra_addr.sin6_len = sizeof(struct sockaddr_in6);
348 	ifra.ifra_addr.sin6_addr.s6_addr16[0] = htons(0xfe80);
349 	ifra.ifra_addr.sin6_addr.s6_addr16[1] = htons(ifp->if_index);
350 	ifra.ifra_addr.sin6_addr.s6_addr32[1] = 0;
351 	if ((ifp->if_flags & IFF_LOOPBACK) != 0) {
352 		ifra.ifra_addr.sin6_addr.s6_addr32[2] = 0;
353 		ifra.ifra_addr.sin6_addr.s6_addr32[3] = htonl(1);
354 	} else {
355 		if (get_ifid(ifp, altifp, &ifra.ifra_addr.sin6_addr) != 0) {
356 			nd6log((LOG_ERR,
357 			    "%s: no ifid available\n", if_name(ifp)));
358 			return (-1);
359 		}
360 	}
361 
362 	ifra.ifra_prefixmask.sin6_len = sizeof(struct sockaddr_in6);
363 	ifra.ifra_prefixmask.sin6_family = AF_INET6;
364 	ifra.ifra_prefixmask.sin6_addr = in6mask64;
365 #ifdef SCOPEDROUTING
366 	/* take into account the sin6_scope_id field for routing */
367 	ifra.ifra_prefixmask.sin6_scope_id = 0xffffffff;
368 #endif
369 	/* link-local addresses should NEVER expire. */
370 	ifra.ifra_lifetime.ia6t_vltime = ND6_INFINITE_LIFETIME;
371 	ifra.ifra_lifetime.ia6t_pltime = ND6_INFINITE_LIFETIME;
372 
373 	/*
374 	 * Do not let in6_update_ifa() do DAD, since we need a random delay
375 	 * before sending an NS at the first time the interface becomes up.
376 	 * Instead, in6_if_up() will start DAD with a proper random delay.
377 	 */
378 	ifra.ifra_flags |= IN6_IFF_NODAD;
379 
380 	/*
381 	 * Now call in6_update_ifa() to do a bunch of procedures to configure
382 	 * a link-local address. We can set NULL to the 3rd argument, because
383 	 * we know there's no other link-local address on the interface
384 	 * and therefore we are adding one (instead of updating one).
385 	 */
386 	if ((error = in6_update_ifa(ifp, &ifra, NULL)) != 0) {
387 		/*
388 		 * XXX: When the interface does not support IPv6, this call
389 		 * would fail in the SIOCSIFADDR ioctl.  I believe the
390 		 * notification is rather confusing in this case, so just
391 		 * suppress it.  (jinmei@kame.net 20010130)
392 		 */
393 		if (error != EAFNOSUPPORT)
394 			nd6log((LOG_NOTICE, "in6_ifattach_linklocal: failed to "
395 			    "configure a link-local address on %s "
396 			    "(errno=%d)\n",
397 			    if_name(ifp), error));
398 		return (-1);
399 	}
400 
401 	/*
402 	 * Adjust ia6_flags so that in6_if_up will perform DAD.
403 	 * XXX: Some P2P interfaces seem not to send packets just after
404 	 * becoming up, so we skip p2p interfaces for safety.
405 	 */
406 	ia = in6ifa_ifpforlinklocal(ifp, 0); /* ia must not be NULL */
407 #ifdef DIAGNOSTIC
408 	if (!ia) {
409 		panic("ia == NULL in in6_ifattach_linklocal");
410 		/* NOTREACHED */
411 	}
412 #endif
413 	if (in6if_do_dad(ifp) && (ifp->if_flags & IFF_POINTOPOINT) == 0) {
414 		ia->ia6_flags &= ~IN6_IFF_NODAD;
415 		ia->ia6_flags |= IN6_IFF_TENTATIVE;
416 	}
417 
418 	/*
419 	 * Make the link-local prefix (fe80::/64%link) as on-link.
420 	 * Since we'd like to manage prefixes separately from addresses,
421 	 * we make an ND6 prefix structure for the link-local prefix,
422 	 * and add it to the prefix list as a never-expire prefix.
423 	 * XXX: this change might affect some existing code base...
424 	 */
425 	bzero(&pr0, sizeof(pr0));
426 	pr0.ndpr_ifp = ifp;
427 	/* this should be 64 at this moment. */
428 	pr0.ndpr_plen = in6_mask2len(&ifra.ifra_prefixmask.sin6_addr, NULL);
429 	pr0.ndpr_mask = ifra.ifra_prefixmask.sin6_addr;
430 	pr0.ndpr_prefix = ifra.ifra_addr;
431 	/* apply the mask for safety. (nd6_prelist_add will apply it again) */
432 	for (i = 0; i < 4; i++) {
433 		pr0.ndpr_prefix.sin6_addr.s6_addr32[i] &=
434 		    in6mask64.s6_addr32[i];
435 	}
436 	/*
437 	 * Initialize parameters.  The link-local prefix must always be
438 	 * on-link, and its lifetimes never expire.
439 	 */
440 	pr0.ndpr_raf_onlink = 1;
441 	pr0.ndpr_raf_auto = 1;	/* probably meaningless */
442 	pr0.ndpr_vltime = ND6_INFINITE_LIFETIME;
443 	pr0.ndpr_pltime = ND6_INFINITE_LIFETIME;
444 	/*
445 	 * Since there is no other link-local addresses, nd6_prefix_lookup()
446 	 * probably returns NULL.  However, we cannot always expect the result.
447 	 * For example, if we first remove the (only) existing link-local
448 	 * address, and then reconfigure another one, the prefix is still
449 	 * valid with referring to the old link-local address.
450 	 */
451 	if (nd6_prefix_lookup(&pr0) == NULL) {
452 		if ((error = nd6_prelist_add(&pr0, NULL, NULL)) != 0)
453 			return (error);
454 	}
455 
456 	return 0;
457 }
458 
459 static int
460 in6_ifattach_loopback(ifp)
461 	struct ifnet *ifp;	/* must be IFT_LOOP */
462 {
463 	struct in6_aliasreq ifra;
464 	int error;
465 
466 	bzero(&ifra, sizeof(ifra));
467 
468 	/*
469 	 * in6_update_ifa() does not use ifra_name, but we accurately set it
470 	 * for safety.
471 	 */
472 	strncpy(ifra.ifra_name, if_name(ifp), sizeof(ifra.ifra_name));
473 
474 	ifra.ifra_prefixmask.sin6_len = sizeof(struct sockaddr_in6);
475 	ifra.ifra_prefixmask.sin6_family = AF_INET6;
476 	ifra.ifra_prefixmask.sin6_addr = in6mask128;
477 
478 	/*
479 	 * Always initialize ia_dstaddr (= broadcast address) to loopback
480 	 * address.  Follows IPv4 practice - see in_ifinit().
481 	 */
482 	ifra.ifra_dstaddr.sin6_len = sizeof(struct sockaddr_in6);
483 	ifra.ifra_dstaddr.sin6_family = AF_INET6;
484 	ifra.ifra_dstaddr.sin6_addr = in6addr_loopback;
485 
486 	ifra.ifra_addr.sin6_len = sizeof(struct sockaddr_in6);
487 	ifra.ifra_addr.sin6_family = AF_INET6;
488 	ifra.ifra_addr.sin6_addr = in6addr_loopback;
489 
490 	/* the loopback  address should NEVER expire. */
491 	ifra.ifra_lifetime.ia6t_vltime = ND6_INFINITE_LIFETIME;
492 	ifra.ifra_lifetime.ia6t_pltime = ND6_INFINITE_LIFETIME;
493 
494 	/* we don't need to perform DAD on loopback interfaces. */
495 	ifra.ifra_flags |= IN6_IFF_NODAD;
496 
497 	/*
498 	 * We are sure that this is a newly assigned address, so we can set
499 	 * NULL to the 3rd arg.
500 	 */
501 	if ((error = in6_update_ifa(ifp, &ifra, NULL)) != 0) {
502 		nd6log((LOG_ERR, "in6_ifattach_loopback: failed to configure "
503 		    "the loopback address on %s (errno=%d)\n",
504 		    if_name(ifp), error));
505 		return (-1);
506 	}
507 
508 	return 0;
509 }
510 
511 /*
512  * compute NI group address, based on the current hostname setting.
513  * see draft-ietf-ipngwg-icmp-name-lookup-* (04 and later).
514  *
515  * when ifp == NULL, the caller is responsible for filling scopeid.
516  */
517 int
518 in6_nigroup(ifp, name, namelen, sa6)
519 	struct ifnet *ifp;
520 	const char *name;
521 	int namelen;
522 	struct sockaddr_in6 *sa6;
523 {
524 	const char *p;
525 	u_int8_t *q;
526 	MD5_CTX ctxt;
527 	u_int8_t digest[16];
528 	u_int8_t l;
529 	u_int8_t n[64];	/* a single label must not exceed 63 chars */
530 
531 	if (!namelen || !name)
532 		return -1;
533 
534 	p = name;
535 	while (p && *p && *p != '.' && p - name < namelen)
536 		p++;
537 	if (p - name > sizeof(n) - 1)
538 		return -1;	/* label too long */
539 	l = p - name;
540 	strncpy((char *)n, name, l);
541 	n[(int)l] = '\0';
542 	for (q = n; *q; q++) {
543 		if ('A' <= *q && *q <= 'Z')
544 			*q = *q - 'A' + 'a';
545 	}
546 
547 	/* generate 8 bytes of pseudo-random value. */
548 	bzero(&ctxt, sizeof(ctxt));
549 	MD5Init(&ctxt);
550 	MD5Update(&ctxt, &l, sizeof(l));
551 	MD5Update(&ctxt, n, l);
552 	MD5Final(digest, &ctxt);
553 
554 	bzero(sa6, sizeof(*sa6));
555 	sa6->sin6_family = AF_INET6;
556 	sa6->sin6_len = sizeof(*sa6);
557 	sa6->sin6_addr.s6_addr16[0] = htons(0xff02);
558 	sa6->sin6_addr.s6_addr16[1] = htons(ifp->if_index);
559 	sa6->sin6_addr.s6_addr8[11] = 2;
560 	bcopy(digest, &sa6->sin6_addr.s6_addr32[3],
561 	    sizeof(sa6->sin6_addr.s6_addr32[3]));
562 
563 	return 0;
564 }
565 
566 /*
567  * XXX multiple loopback interface needs more care.  for instance,
568  * nodelocal address needs to be configured onto only one of them.
569  * XXX multiple link-local address case
570  */
571 void
572 in6_ifattach(ifp, altifp)
573 	struct ifnet *ifp;
574 	struct ifnet *altifp;	/* secondary EUI64 source */
575 {
576 	struct in6_ifaddr *ia;
577 	struct in6_addr in6;
578 
579 	/* some of the interfaces are inherently not IPv6 capable */
580 	switch (ifp->if_type) {
581 	case IFT_BRIDGE:
582 		return;
583 	}
584 
585 	/*
586 	 * if link mtu is too small, don't try to configure IPv6.
587 	 * remember there could be some link-layer that has special
588 	 * fragmentation logic.
589 	 */
590 	if (ifp->if_mtu < IPV6_MMTU) {
591 		nd6log((LOG_INFO, "in6_ifattach: "
592 		    "%s has too small MTU, IPv6 not enabled\n",
593 		    if_name(ifp)));
594 		return;
595 	}
596 
597 	/* create a multicast kludge storage (if we have not had one) */
598 	in6_createmkludge(ifp);
599 
600 	/*
601 	 * quirks based on interface type
602 	 */
603 	switch (ifp->if_type) {
604 #ifdef IFT_STF
605 	case IFT_STF:
606 		/*
607 		 * 6to4 interface is a very special kind of beast.
608 		 * no multicast, no linklocal.  RFC2529 specifies how to make
609 		 * linklocals for 6to4 interface, but there's no use and
610 		 * it is rather harmful to have one.
611 		 */
612 		return;
613 #endif
614 	default:
615 		break;
616 	}
617 
618 	/*
619 	 * usually, we require multicast capability to the interface
620 	 */
621 	if ((ifp->if_flags & IFF_MULTICAST) == 0) {
622 		nd6log((LOG_INFO, "in6_ifattach: "
623 		    "%s is not multicast capable, IPv6 not enabled\n",
624 		    if_name(ifp)));
625 		return;
626 	}
627 
628 	/*
629 	 * assign loopback address for loopback interface.
630 	 * XXX multiple loopback interface case.
631 	 */
632 	if ((ifp->if_flags & IFF_LOOPBACK) != 0) {
633 		in6 = in6addr_loopback;
634 		if (in6ifa_ifpwithaddr(ifp, &in6) == NULL) {
635 			if (in6_ifattach_loopback(ifp) != 0)
636 				return;
637 		}
638 	}
639 
640 	/*
641 	 * assign a link-local address, if there's none.
642 	 */
643 	if (ip6_auto_linklocal) {
644 		ia = in6ifa_ifpforlinklocal(ifp, 0);
645 		if (ia == NULL) {
646 			if (in6_ifattach_linklocal(ifp, altifp) == 0) {
647 				/* linklocal address assigned */
648 			} else {
649 				/* failed to assign linklocal address. bark? */
650 			}
651 		}
652 	}
653 }
654 
655 /*
656  * NOTE: in6_ifdetach() does not support loopback if at this moment.
657  * We don't need this function in bsdi, because interfaces are never removed
658  * from the ifnet list in bsdi.
659  */
660 void
661 in6_ifdetach(ifp)
662 	struct ifnet *ifp;
663 {
664 	struct in6_ifaddr *ia, *oia;
665 	struct ifaddr *ifa, *next;
666 	struct rtentry *rt;
667 	short rtflags;
668 	struct sockaddr_in6 sin6;
669 	struct in6_multi_mship *imm;
670 
671 	/* remove neighbor management table */
672 	nd6_purge(ifp);
673 
674 	/* nuke any of IPv6 addresses we have */
675 	for (ifa = ifp->if_addrlist.tqh_first; ifa; ifa = next)
676 	{
677 		next = ifa->ifa_list.tqe_next;
678 		if (ifa->ifa_addr->sa_family != AF_INET6)
679 			continue;
680 		in6_purgeaddr(ifa);
681 	}
682 
683 	/* undo everything done by in6_ifattach(), just in case */
684 	for (ifa = ifp->if_addrlist.tqh_first; ifa; ifa = next)
685 	{
686 		next = ifa->ifa_list.tqe_next;
687 
688 		if (ifa->ifa_addr->sa_family != AF_INET6
689 		 || !IN6_IS_ADDR_LINKLOCAL(&satosin6(&ifa->ifa_addr)->sin6_addr)) {
690 			continue;
691 		}
692 
693 		ia = (struct in6_ifaddr *)ifa;
694 
695 		/*
696 		 * leave from multicast groups we have joined for the interface
697 		 */
698 		while ((imm = ia->ia6_memberships.lh_first) != NULL) {
699 			LIST_REMOVE(imm, i6mm_chain);
700 			in6_leavegroup(imm);
701 		}
702 
703 		/* remove from the routing table */
704 		if ((ia->ia_flags & IFA_ROUTE) &&
705 		    (rt = rtalloc1((struct sockaddr *)&ia->ia_addr, 0))) {
706 			rtflags = rt->rt_flags;
707 			rtfree(rt);
708 			rtrequest(RTM_DELETE, (struct sockaddr *)&ia->ia_addr,
709 			    (struct sockaddr *)&ia->ia_addr,
710 			    (struct sockaddr *)&ia->ia_prefixmask,
711 			    rtflags, (struct rtentry **)0);
712 		}
713 
714 		/* remove from the linked list */
715 		TAILQ_REMOVE(&ifp->if_addrlist, (struct ifaddr *)ia, ifa_list);
716 		IFAFREE(&ia->ia_ifa);
717 
718 		/* also remove from the IPv6 address chain(itojun&jinmei) */
719 		oia = ia;
720 		if (oia == (ia = in6_ifaddr))
721 			in6_ifaddr = ia->ia_next;
722 		else {
723 			while (ia->ia_next && (ia->ia_next != oia))
724 				ia = ia->ia_next;
725 			if (ia->ia_next)
726 				ia->ia_next = oia->ia_next;
727 			else {
728 				nd6log((LOG_ERR,
729 				    "%s: didn't unlink in6ifaddr from list\n",
730 				    if_name(ifp)));
731 			}
732 		}
733 
734 		IFAFREE(&oia->ia_ifa);
735 	}
736 
737 	/* cleanup multicast address kludge table, if there is any */
738 	in6_purgemkludge(ifp);
739 
740 	/*
741 	 * remove neighbor management table.  we call it twice just to make
742 	 * sure we nuke everything.  maybe we need just one call.
743 	 * XXX: since the first call did not release addresses, some prefixes
744 	 * might remain.  We should call nd6_purge() again to release the
745 	 * prefixes after removing all addresses above.
746 	 * (Or can we just delay calling nd6_purge until at this point?)
747 	 */
748 	nd6_purge(ifp);
749 
750 	/* remove route to link-local allnodes multicast (ff02::1) */
751 	bzero(&sin6, sizeof(sin6));
752 	sin6.sin6_len = sizeof(struct sockaddr_in6);
753 	sin6.sin6_family = AF_INET6;
754 	sin6.sin6_addr = in6addr_linklocal_allnodes;
755 	sin6.sin6_addr.s6_addr16[1] = htons(ifp->if_index);
756 	rt = rtalloc1((struct sockaddr *)&sin6, 0);
757 	if (rt && rt->rt_ifp == ifp) {
758 		rtrequest(RTM_DELETE, (struct sockaddr *)rt_key(rt),
759 		    rt->rt_gateway, rt_mask(rt), rt->rt_flags, 0);
760 		rtfree(rt);
761 	}
762 }
763