xref: /openbsd-src/sys/netinet6/nd6_rtr.c (revision 50b7afb2c2c0993b0894d4e34bf857cb13ed9c80)
1 /*	$OpenBSD: nd6_rtr.c,v 1.83 2014/07/12 18:44:23 tedu Exp $	*/
2 /*	$KAME: nd6_rtr.c,v 1.97 2001/02/07 11:09:13 itojun 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/param.h>
34 #include <sys/systm.h>
35 #include <sys/malloc.h>
36 #include <sys/mbuf.h>
37 #include <sys/socket.h>
38 #include <sys/sockio.h>
39 #include <sys/time.h>
40 #include <sys/kernel.h>
41 #include <sys/errno.h>
42 #include <sys/ioctl.h>
43 #include <sys/syslog.h>
44 #include <sys/queue.h>
45 #include <sys/workq.h>
46 #include <dev/rndvar.h>
47 
48 #include <net/if.h>
49 #include <net/if_types.h>
50 #include <net/if_dl.h>
51 #include <net/route.h>
52 #include <net/radix.h>
53 
54 #include <netinet/in.h>
55 #include <netinet6/in6_var.h>
56 #include <netinet/ip6.h>
57 #include <netinet6/ip6_var.h>
58 #include <netinet6/nd6.h>
59 #include <netinet/icmp6.h>
60 
61 #include <dev/rndvar.h>
62 
63 #define SDL(s)	((struct sockaddr_dl *)s)
64 
65 int rtpref(struct nd_defrouter *);
66 struct nd_defrouter *defrtrlist_update(struct nd_defrouter *);
67 struct in6_ifaddr *in6_ifadd(struct nd_prefix *, int);
68 struct nd_pfxrouter *pfxrtr_lookup(struct nd_prefix *, struct nd_defrouter *);
69 void pfxrtr_add(struct nd_prefix *, struct nd_defrouter *);
70 void pfxrtr_del(struct nd_pfxrouter *);
71 struct nd_pfxrouter *find_pfxlist_reachable_router(struct nd_prefix *);
72 void defrouter_delreq(struct nd_defrouter *);
73 void purge_detached(struct ifnet *);
74 
75 void in6_init_address_ltimes(struct nd_prefix *, struct in6_addrlifetime *);
76 
77 int rt6_deleteroute(struct radix_node *, void *, u_int);
78 
79 void nd6_addr_add(void *, void *);
80 
81 extern int nd6_recalc_reachtm_interval;
82 
83 /*
84  * Receive Router Solicitation Message - just for routers.
85  * Router solicitation/advertisement is mostly managed by userland program
86  * (rtadvd) so here we have no function like nd6_ra_output().
87  *
88  * Based on RFC 2461
89  */
90 void
91 nd6_rs_input(struct mbuf *m, int off, int icmp6len)
92 {
93 	struct ifnet *ifp = m->m_pkthdr.rcvif;
94 	struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
95 	struct nd_router_solicit *nd_rs;
96 	struct in6_addr saddr6 = ip6->ip6_src;
97 #if 0
98 	struct in6_addr daddr6 = ip6->ip6_dst;
99 #endif
100 	char *lladdr = NULL;
101 	int lladdrlen = 0;
102 #if 0
103 	struct sockaddr_dl *sdl = NULL;
104 	struct llinfo_nd6 *ln = NULL;
105 	struct rtentry *rt = NULL;
106 	int is_newentry;
107 #endif
108 	union nd_opts ndopts;
109 	char src[INET6_ADDRSTRLEN], dst[INET6_ADDRSTRLEN];
110 
111 	/* If I'm not a router, ignore it. XXX - too restrictive? */
112 	if (!ip6_forwarding || (ifp->if_xflags & IFXF_AUTOCONF6))
113 		goto freeit;
114 
115 	/* Sanity checks */
116 	if (ip6->ip6_hlim != 255) {
117 		nd6log((LOG_ERR,
118 		    "nd6_rs_input: invalid hlim (%d) from %s to %s on %s\n",
119 		    ip6->ip6_hlim,
120 		    inet_ntop(AF_INET6, &ip6->ip6_src, src, sizeof(src)),
121 		    inet_ntop(AF_INET6, &ip6->ip6_dst, dst, sizeof(dst)),
122 		    ifp->if_xname));
123 		goto bad;
124 	}
125 
126 	/*
127 	 * Don't update the neighbor cache, if src = ::.
128 	 * This indicates that the src has no IP address assigned yet.
129 	 */
130 	if (IN6_IS_ADDR_UNSPECIFIED(&saddr6))
131 		goto freeit;
132 
133 	IP6_EXTHDR_GET(nd_rs, struct nd_router_solicit *, m, off, icmp6len);
134 	if (nd_rs == NULL) {
135 		icmp6stat.icp6s_tooshort++;
136 		return;
137 	}
138 
139 	icmp6len -= sizeof(*nd_rs);
140 	nd6_option_init(nd_rs + 1, icmp6len, &ndopts);
141 	if (nd6_options(&ndopts) < 0) {
142 		nd6log((LOG_INFO,
143 		    "nd6_rs_input: invalid ND option, ignored\n"));
144 		/* nd6_options have incremented stats */
145 		goto freeit;
146 	}
147 
148 	if (ndopts.nd_opts_src_lladdr) {
149 		lladdr = (char *)(ndopts.nd_opts_src_lladdr + 1);
150 		lladdrlen = ndopts.nd_opts_src_lladdr->nd_opt_len << 3;
151 	}
152 
153 	if (lladdr && ((ifp->if_addrlen + 2 + 7) & ~7) != lladdrlen) {
154 		nd6log((LOG_INFO,
155 		    "nd6_rs_input: lladdrlen mismatch for %s "
156 		    "(if %d, RS packet %d)\n",
157 		    inet_ntop(AF_INET6, &saddr6, src, sizeof(src)),
158 		    ifp->if_addrlen, lladdrlen - 2));
159 		goto bad;
160 	}
161 
162 	nd6_cache_lladdr(ifp, &saddr6, lladdr, lladdrlen, ND_ROUTER_SOLICIT, 0);
163 
164  freeit:
165 	m_freem(m);
166 	return;
167 
168  bad:
169 	icmp6stat.icp6s_badrs++;
170 	m_freem(m);
171 }
172 
173 /*
174  * Receive Router Advertisement Message.
175  *
176  * Based on RFC 2461
177  * TODO: on-link bit on prefix information
178  * TODO: ND_RA_FLAG_{OTHER,MANAGED} processing
179  */
180 void
181 nd6_ra_input(struct mbuf *m, int off, int icmp6len)
182 {
183 	struct ifnet *ifp = m->m_pkthdr.rcvif;
184 	struct nd_ifinfo *ndi = ND_IFINFO(ifp);
185 	struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
186 	struct nd_router_advert *nd_ra;
187 	struct in6_addr saddr6 = ip6->ip6_src;
188 #if 0
189 	struct in6_addr daddr6 = ip6->ip6_dst;
190 	int flags; /* = nd_ra->nd_ra_flags_reserved; */
191 	int is_managed = ((flags & ND_RA_FLAG_MANAGED) != 0);
192 	int is_other = ((flags & ND_RA_FLAG_OTHER) != 0);
193 #endif
194 	union nd_opts ndopts;
195 	struct nd_defrouter *dr;
196 	char src[INET6_ADDRSTRLEN], dst[INET6_ADDRSTRLEN];
197 
198 	/* We accept RAs only if inet6 autoconf is enabled  */
199 	if (!(ifp->if_xflags & IFXF_AUTOCONF6))
200 		goto freeit;
201 	if (!(ndi->flags & ND6_IFF_ACCEPT_RTADV))
202 		goto freeit;
203 
204 	if (ip6->ip6_hlim != 255) {
205 		nd6log((LOG_ERR,
206 		    "nd6_ra_input: invalid hlim (%d) from %s to %s on %s\n",
207 		    ip6->ip6_hlim,
208 		    inet_ntop(AF_INET6, &ip6->ip6_src, src, sizeof(src)),
209 		    inet_ntop(AF_INET6, &ip6->ip6_dst, dst, sizeof(dst)),
210 		    ifp->if_xname));
211 		goto bad;
212 	}
213 
214 	if (!IN6_IS_ADDR_LINKLOCAL(&saddr6)) {
215 		nd6log((LOG_ERR,
216 		    "nd6_ra_input: src %s is not link-local\n",
217 		    inet_ntop(AF_INET6, &saddr6, src, sizeof(src))));
218 		goto bad;
219 	}
220 
221 	IP6_EXTHDR_GET(nd_ra, struct nd_router_advert *, m, off, icmp6len);
222 	if (nd_ra == NULL) {
223 		icmp6stat.icp6s_tooshort++;
224 		return;
225 	}
226 
227 	icmp6len -= sizeof(*nd_ra);
228 	nd6_option_init(nd_ra + 1, icmp6len, &ndopts);
229 	if (nd6_options(&ndopts) < 0) {
230 		nd6log((LOG_INFO,
231 		    "nd6_ra_input: invalid ND option, ignored\n"));
232 		/* nd6_options have incremented stats */
233 		goto freeit;
234 	}
235 
236     {
237 	struct nd_defrouter dr0;
238 	u_int32_t advreachable = nd_ra->nd_ra_reachable;
239 
240 	memset(&dr0, 0, sizeof(dr0));
241 	dr0.rtaddr = saddr6;
242 	dr0.flags  = nd_ra->nd_ra_flags_reserved;
243 	dr0.rtlifetime = ntohs(nd_ra->nd_ra_router_lifetime);
244 	dr0.expire = time_second + dr0.rtlifetime;
245 	dr0.ifp = ifp;
246 	/* unspecified or not? (RFC 2461 6.3.4) */
247 	if (advreachable) {
248 		NTOHL(advreachable);
249 		if (advreachable <= MAX_REACHABLE_TIME &&
250 		    ndi->basereachable != advreachable) {
251 			ndi->basereachable = advreachable;
252 			ndi->reachable = ND_COMPUTE_RTIME(ndi->basereachable);
253 			ndi->recalctm = nd6_recalc_reachtm_interval; /* reset */
254 		}
255 	}
256 	if (nd_ra->nd_ra_retransmit)
257 		ndi->retrans = ntohl(nd_ra->nd_ra_retransmit);
258 	if (nd_ra->nd_ra_curhoplimit)
259 		ndi->chlim = nd_ra->nd_ra_curhoplimit;
260 	dr = defrtrlist_update(&dr0);
261     }
262 
263 	/*
264 	 * prefix
265 	 */
266 	if (ndopts.nd_opts_pi) {
267 		struct nd_opt_hdr *pt;
268 		struct nd_opt_prefix_info *pi = NULL;
269 		struct nd_prefix pr;
270 
271 		for (pt = (struct nd_opt_hdr *)ndopts.nd_opts_pi;
272 		     pt <= (struct nd_opt_hdr *)ndopts.nd_opts_pi_end;
273 		     pt = (struct nd_opt_hdr *)((caddr_t)pt +
274 						(pt->nd_opt_len << 3))) {
275 			if (pt->nd_opt_type != ND_OPT_PREFIX_INFORMATION)
276 				continue;
277 			pi = (struct nd_opt_prefix_info *)pt;
278 
279 			if (pi->nd_opt_pi_len != 4) {
280 				nd6log((LOG_INFO,
281 				    "nd6_ra_input: invalid option "
282 				    "len %d for prefix information option, "
283 				    "ignored\n", pi->nd_opt_pi_len));
284 				continue;
285 			}
286 
287 			if (128 < pi->nd_opt_pi_prefix_len) {
288 				nd6log((LOG_INFO,
289 				    "nd6_ra_input: invalid prefix "
290 				    "len %d for prefix information option, "
291 				    "ignored\n", pi->nd_opt_pi_prefix_len));
292 				continue;
293 			}
294 
295 			if (IN6_IS_ADDR_MULTICAST(&pi->nd_opt_pi_prefix)
296 			 || IN6_IS_ADDR_LINKLOCAL(&pi->nd_opt_pi_prefix)) {
297 				nd6log((LOG_INFO,
298 				    "nd6_ra_input: invalid prefix "
299 				    "%s, ignored\n",
300 				    inet_ntop(AF_INET6, &pi->nd_opt_pi_prefix,
301 					src, sizeof(src))));
302 				continue;
303 			}
304 
305 			/* aggregatable unicast address, rfc2374 */
306 			if ((pi->nd_opt_pi_prefix.s6_addr8[0] & 0xe0) == 0x20
307 			 && pi->nd_opt_pi_prefix_len != 64) {
308 				nd6log((LOG_INFO,
309 				    "nd6_ra_input: invalid prefixlen "
310 				    "%d for rfc2374 prefix %s, ignored\n",
311 				    pi->nd_opt_pi_prefix_len,
312 				    inet_ntop(AF_INET6, &pi->nd_opt_pi_prefix,
313 					src, sizeof(src))));
314 				continue;
315 			}
316 
317 			bzero(&pr, sizeof(pr));
318 			pr.ndpr_prefix.sin6_family = AF_INET6;
319 			pr.ndpr_prefix.sin6_len = sizeof(pr.ndpr_prefix);
320 			pr.ndpr_prefix.sin6_addr = pi->nd_opt_pi_prefix;
321 			pr.ndpr_ifp = (struct ifnet *)m->m_pkthdr.rcvif;
322 
323 			pr.ndpr_raf_onlink = (pi->nd_opt_pi_flags_reserved &
324 			     ND_OPT_PI_FLAG_ONLINK) ? 1 : 0;
325 			pr.ndpr_raf_auto = (pi->nd_opt_pi_flags_reserved &
326 			     ND_OPT_PI_FLAG_AUTO) ? 1 : 0;
327 			pr.ndpr_plen = pi->nd_opt_pi_prefix_len;
328 			pr.ndpr_vltime = ntohl(pi->nd_opt_pi_valid_time);
329 			pr.ndpr_pltime = ntohl(pi->nd_opt_pi_preferred_time);
330 			pr.ndpr_lastupdate = time_second;
331 
332 			if (in6_init_prefix_ltimes(&pr))
333 				continue; /* prefix lifetime init failed */
334 
335 			(void)prelist_update(&pr, dr, m);
336 		}
337 	}
338 
339 	/*
340 	 * MTU
341 	 */
342 	if (ndopts.nd_opts_mtu && ndopts.nd_opts_mtu->nd_opt_mtu_len == 1) {
343 		u_long mtu;
344 		u_long maxmtu;
345 
346 		mtu = ntohl(ndopts.nd_opts_mtu->nd_opt_mtu_mtu);
347 
348 		/* lower bound */
349 		if (mtu < IPV6_MMTU) {
350 			nd6log((LOG_INFO, "nd6_ra_input: bogus mtu option "
351 			    "mtu=%lu sent from %s, ignoring\n",
352 			    mtu,
353 			    inet_ntop(AF_INET6, &ip6->ip6_src,
354 				src, sizeof(src))));
355 			goto skip;
356 		}
357 
358 		/* upper bound */
359 		maxmtu = (ndi->maxmtu && ndi->maxmtu < ifp->if_mtu)
360 		    ? ndi->maxmtu : ifp->if_mtu;
361 		if (mtu <= maxmtu) {
362 			int change = (ndi->linkmtu != mtu);
363 
364 			ndi->linkmtu = mtu;
365 			if (change) /* in6_maxmtu may change */
366 				in6_setmaxmtu();
367 		} else {
368 			nd6log((LOG_INFO, "nd6_ra_input: bogus mtu "
369 			    "mtu=%lu sent from %s; "
370 			    "exceeds maxmtu %lu, ignoring\n",
371 			    mtu,
372 			    inet_ntop(AF_INET6, &ip6->ip6_src,
373 				src, sizeof(src)),
374 			    maxmtu));
375 		}
376 	}
377 
378  skip:
379 
380 	/*
381 	 * Source link layer address
382 	 */
383     {
384 	char *lladdr = NULL;
385 	int lladdrlen = 0;
386 
387 	if (ndopts.nd_opts_src_lladdr) {
388 		lladdr = (char *)(ndopts.nd_opts_src_lladdr + 1);
389 		lladdrlen = ndopts.nd_opts_src_lladdr->nd_opt_len << 3;
390 	}
391 
392 	if (lladdr && ((ifp->if_addrlen + 2 + 7) & ~7) != lladdrlen) {
393 		nd6log((LOG_INFO,
394 		    "nd6_ra_input: lladdrlen mismatch for %s "
395 		    "(if %d, RA packet %d)\n",
396 		    inet_ntop(AF_INET6, &saddr6, src, sizeof(src)),
397 		    ifp->if_addrlen, lladdrlen - 2));
398 		goto bad;
399 	}
400 
401 	nd6_cache_lladdr(ifp, &saddr6, lladdr, lladdrlen, ND_ROUTER_ADVERT, 0);
402 
403 	/*
404 	 * Installing a link-layer address might change the state of the
405 	 * router's neighbor cache, which might also affect our on-link
406 	 * detection of adveritsed prefixes.
407 	 */
408 	pfxlist_onlink_check();
409     }
410 
411  freeit:
412 	m_freem(m);
413 	return;
414 
415  bad:
416 	icmp6stat.icp6s_badra++;
417 	m_freem(m);
418 }
419 
420 /*
421  * default router list processing sub routines
422  */
423 void
424 defrouter_addreq(struct nd_defrouter *new)
425 {
426 	struct rt_addrinfo info;
427 	struct sockaddr_in6 def, mask, gate;
428 	struct rtentry *newrt = NULL;
429 	int s;
430 	int error;
431 
432 	memset(&def, 0, sizeof(def));
433 	memset(&mask, 0, sizeof(mask));
434 	memset(&gate, 0, sizeof(gate)); /* for safety */
435 	memset(&info, 0, sizeof(info));
436 
437 	def.sin6_len = mask.sin6_len = gate.sin6_len =
438 	    sizeof(struct sockaddr_in6);
439 	def.sin6_family = mask.sin6_family = gate.sin6_family = AF_INET6;
440 	gate.sin6_addr = new->rtaddr;
441 	gate.sin6_scope_id = 0;	/* XXX */
442 
443 	info.rti_flags = RTF_GATEWAY;
444 	info.rti_info[RTAX_DST] = sin6tosa(&def);
445 	info.rti_info[RTAX_GATEWAY] = sin6tosa(&gate);
446 	info.rti_info[RTAX_NETMASK] = sin6tosa(&mask);
447 
448 	s = splsoftnet();
449 	error = rtrequest1(RTM_ADD, &info, RTP_DEFAULT, &newrt,
450 	    new->ifp->if_rdomain);
451 	if (newrt) {
452 		rt_sendmsg(newrt, RTM_ADD, new->ifp->if_rdomain);
453 		newrt->rt_refcnt--;
454 	}
455 	if (error == 0)
456 		new->installed = 1;
457 	splx(s);
458 	return;
459 }
460 
461 struct nd_defrouter *
462 defrouter_lookup(struct in6_addr *addr, struct ifnet *ifp)
463 {
464 	struct nd_defrouter *dr;
465 
466 	TAILQ_FOREACH(dr, &nd_defrouter, dr_entry)
467 		if (dr->ifp == ifp && IN6_ARE_ADDR_EQUAL(addr, &dr->rtaddr))
468 			return (dr);
469 
470 	return (NULL);		/* search failed */
471 }
472 
473 void
474 defrtrlist_del(struct nd_defrouter *dr)
475 {
476 	struct nd_defrouter *deldr = NULL;
477 	struct in6_ifextra *ext = dr->ifp->if_afdata[AF_INET6];
478 	struct nd_prefix *pr;
479 
480 	/*
481 	 * Flush all the routing table entries that use the router
482 	 * as a next hop.
483 	 */
484 	/* XXX: better condition? */
485 	if (!ip6_forwarding && (dr->ifp->if_xflags & IFXF_AUTOCONF6))
486 		rt6_flush(&dr->rtaddr, dr->ifp);
487 
488 	if (dr->installed) {
489 		deldr = dr;
490 		defrouter_delreq(dr);
491 	}
492 	TAILQ_REMOVE(&nd_defrouter, dr, dr_entry);
493 
494 	/*
495 	 * Also delete all the pointers to the router in each prefix lists.
496 	 */
497 	LIST_FOREACH(pr, &nd_prefix, ndpr_entry) {
498 		struct nd_pfxrouter *pfxrtr;
499 		if ((pfxrtr = pfxrtr_lookup(pr, dr)) != NULL)
500 			pfxrtr_del(pfxrtr);
501 	}
502 	pfxlist_onlink_check();
503 
504 	/*
505 	 * If the router is the primary one, choose a new one.
506 	 * Note that defrouter_select() will remove the current gateway
507 	 * from the routing table.
508 	 */
509 	if (deldr)
510 		defrouter_select();
511 
512 	ext->ndefrouters--;
513 	if (ext->ndefrouters < 0) {
514 		log(LOG_WARNING, "defrtrlist_del: negative count on %s\n",
515 		    dr->ifp->if_xname);
516 	}
517 
518 	free(dr, M_IP6NDP, 0);
519 }
520 
521 /*
522  * Remove the default route for a given router.
523  * This is just a subroutine function for defrouter_select(), and should
524  * not be called from anywhere else.
525  */
526 void
527 defrouter_delreq(struct nd_defrouter *dr)
528 {
529 	struct rt_addrinfo info;
530 	struct sockaddr_in6 def, mask, gw;
531 	struct rtentry *oldrt = NULL;
532 
533 #ifdef DIAGNOSTIC
534 	if (!dr)
535 		panic("dr == NULL in defrouter_delreq");
536 #endif
537 
538 	memset(&info, 0, sizeof(info));
539 	memset(&def, 0, sizeof(def));
540 	memset(&mask, 0, sizeof(mask));
541 	memset(&gw, 0, sizeof(gw));	/* for safety */
542 
543 	def.sin6_len = mask.sin6_len = gw.sin6_len =
544 	    sizeof(struct sockaddr_in6);
545 	def.sin6_family = mask.sin6_family = gw.sin6_family = AF_INET6;
546 	gw.sin6_addr = dr->rtaddr;
547 	gw.sin6_scope_id = 0;	/* XXX */
548 
549 	info.rti_flags = RTF_GATEWAY;
550 	info.rti_info[RTAX_DST] = sin6tosa(&def);
551 	info.rti_info[RTAX_GATEWAY] = sin6tosa(&gw);
552 	info.rti_info[RTAX_NETMASK] = sin6tosa(&mask);
553 
554 	rtrequest1(RTM_DELETE, &info, RTP_DEFAULT, &oldrt,
555 	    dr->ifp->if_rdomain);
556 	if (oldrt) {
557 		rt_sendmsg(oldrt, RTM_DELETE, dr->ifp->if_rdomain);
558 		if (oldrt->rt_refcnt <= 0) {
559 			/*
560 			 * XXX: borrowed from the RTM_DELETE case of
561 			 * rtrequest1().
562 			 */
563 			oldrt->rt_refcnt++;
564 			rtfree(oldrt);
565 		}
566 	}
567 
568 	dr->installed = 0;
569 }
570 
571 /*
572  * remove all default routes from default router list
573  */
574 void
575 defrouter_reset(void)
576 {
577 	struct nd_defrouter *dr;
578 
579 	TAILQ_FOREACH(dr, &nd_defrouter, dr_entry)
580 		defrouter_delreq(dr);
581 
582 	/*
583 	 * XXX should we also nuke any default routers in the kernel, by
584 	 * going through them by rtalloc1()?
585 	 */
586 }
587 
588 /*
589  * Default Router Selection according to Section 6.3.6 of RFC 2461 and
590  * draft-ietf-ipngwg-router-selection:
591  * 1) Routers that are reachable or probably reachable should be preferred.
592  *    If we have more than one (probably) reachable router, prefer ones
593  *    with the highest router preference.
594  * 2) When no routers on the list are known to be reachable or
595  *    probably reachable, routers SHOULD be selected in a round-robin
596  *    fashion, regardless of router preference values.
597  * 3) If the Default Router List is empty, assume that all
598  *    destinations are on-link.
599  *
600  * We assume nd_defrouter is sorted by router preference value.
601  * Since the code below covers both with and without router preference cases,
602  * we do not need to classify the cases by ifdef.
603  *
604  * At this moment, we do not try to install more than one default router,
605  * even when the multipath routing is available, because we're not sure about
606  * the benefits for stub hosts comparing to the risk of making the code
607  * complicated and the possibility of introducing bugs.
608  */
609 void
610 defrouter_select(void)
611 {
612 	int s = splsoftnet();
613 	struct nd_defrouter *dr, *selected_dr = NULL, *installed_dr = NULL;
614 	struct rtentry *rt = NULL;
615 	struct llinfo_nd6 *ln = NULL;
616 
617 	/*
618 	 * This function should be called only when acting as an autoconfigured
619 	 * host.  Although the remaining part of this function is not effective
620 	 * if the node is not an autoconfigured host, we explicitly exclude
621 	 * such cases here for safety.
622 	 */
623 	/* XXX too strict? */
624 	if (ip6_forwarding) {
625 		nd6log((LOG_WARNING,
626 		    "defrouter_select: called unexpectedly (forwarding=%d)\n",
627 		    ip6_forwarding));
628 		splx(s);
629 		return;
630 	}
631 
632 	/*
633 	 * Let's handle easy case (3) first:
634 	 * If default router list is empty, there's nothing to be done.
635 	 */
636 	if (TAILQ_EMPTY(&nd_defrouter)) {
637 		splx(s);
638 		return;
639 	}
640 
641 	/*
642 	 * Search for a (probably) reachable router from the list.
643 	 * We just pick up the first reachable one (if any), assuming that
644 	 * the ordering rule of the list described in defrtrlist_update().
645 	 */
646 	TAILQ_FOREACH(dr, &nd_defrouter, dr_entry) {
647 		if (!(dr->ifp->if_xflags & IFXF_AUTOCONF6))
648 			continue;
649 		if (!selected_dr &&
650 		    (rt = nd6_lookup(&dr->rtaddr, 0, dr->ifp,
651 		     dr->ifp->if_rdomain)) &&
652 		    (ln = (struct llinfo_nd6 *)rt->rt_llinfo) &&
653 		    ND6_IS_LLINFO_PROBREACH(ln)) {
654 			selected_dr = dr;
655 		}
656 
657 		if (dr->installed && !installed_dr)
658 			installed_dr = dr;
659 		else if (dr->installed && installed_dr) {
660 			/* this should not happen.  warn for diagnosis. */
661 			log(LOG_ERR, "defrouter_select: more than one router"
662 			    " is installed\n");
663 		}
664 	}
665 	/*
666 	 * If none of the default routers was found to be reachable,
667 	 * round-robin the list regardless of preference.
668 	 * Otherwise, if we have an installed router, check if the selected
669 	 * (reachable) router should really be preferred to the installed one.
670 	 * We only prefer the new router when the old one is not reachable
671 	 * or when the new one has a really higher preference value.
672 	 */
673 	if (!selected_dr) {
674 		if (!installed_dr || !TAILQ_NEXT(installed_dr, dr_entry))
675 			selected_dr = TAILQ_FIRST(&nd_defrouter);
676 		else
677 			selected_dr = TAILQ_NEXT(installed_dr, dr_entry);
678 	} else if (installed_dr &&
679 	    (rt = nd6_lookup(&installed_dr->rtaddr, 0, installed_dr->ifp,
680 	     installed_dr->ifp->if_rdomain)) &&
681 	    (ln = (struct llinfo_nd6 *)rt->rt_llinfo) &&
682 	    ND6_IS_LLINFO_PROBREACH(ln) &&
683 	    rtpref(selected_dr) <= rtpref(installed_dr)) {
684 		selected_dr = installed_dr;
685 	}
686 
687 	/*
688 	 * If the selected router is different than the installed one,
689 	 * remove the installed router and install the selected one.
690 	 * Note that the selected router is never NULL here.
691 	 */
692 	if (installed_dr != selected_dr) {
693 		if (installed_dr)
694 			defrouter_delreq(installed_dr);
695 		defrouter_addreq(selected_dr);
696 	}
697 
698 	splx(s);
699 	return;
700 }
701 
702 /*
703  * for default router selection
704  * regards router-preference field as a 2-bit signed integer
705  */
706 int
707 rtpref(struct nd_defrouter *dr)
708 {
709 #ifdef RTPREF
710 	switch (dr->flags & ND_RA_FLAG_RTPREF_MASK) {
711 	case ND_RA_FLAG_RTPREF_HIGH:
712 		return RTPREF_HIGH;
713 	case ND_RA_FLAG_RTPREF_MEDIUM:
714 	case ND_RA_FLAG_RTPREF_RSV:
715 		return RTPREF_MEDIUM;
716 	case ND_RA_FLAG_RTPREF_LOW:
717 		return RTPREF_LOW;
718 	default:
719 		/*
720 		 * This case should never happen.  If it did, it would mean a
721 		 * serious bug of kernel internal.  We thus always bark here.
722 		 * Or, can we even panic?
723 		 */
724 		log(LOG_ERR, "rtpref: impossible RA flag %x", dr->flags);
725 		return RTPREF_INVALID;
726 	}
727 	/* NOTREACHED */
728 #else
729 	return 0;
730 #endif
731 }
732 
733 struct nd_defrouter *
734 defrtrlist_update(struct nd_defrouter *new)
735 {
736 	struct nd_defrouter *dr, *n;
737 	struct in6_ifextra *ext = new->ifp->if_afdata[AF_INET6];
738 	int s = splsoftnet();
739 
740 	if ((dr = defrouter_lookup(&new->rtaddr, new->ifp)) != NULL) {
741 		/* entry exists */
742 		if (new->rtlifetime == 0) {
743 			defrtrlist_del(dr);
744 			dr = NULL;
745 		} else {
746 			int oldpref = rtpref(dr);
747 
748 			/* override */
749 			dr->flags = new->flags; /* xxx flag check */
750 			dr->rtlifetime = new->rtlifetime;
751 			dr->expire = new->expire;
752 
753 			if (!dr->installed)
754 				defrouter_select();
755 
756 			/*
757 			 * If the preference does not change, there's no need
758 			 * to sort the entries.
759 			 */
760 			if (rtpref(new) == oldpref) {
761 				splx(s);
762 				return (dr);
763 			}
764 
765 			/*
766 			 * preferred router may be changed, so relocate
767 			 * this router.
768 			 * XXX: calling TAILQ_REMOVE directly is a bad manner.
769 			 * However, since defrtrlist_del() has many side
770 			 * effects, we intentionally do so here.
771 			 * defrouter_select() below will handle routing
772 			 * changes later.
773 			 */
774 			TAILQ_REMOVE(&nd_defrouter, dr, dr_entry);
775 			n = dr;
776 			goto insert;
777 		}
778 		splx(s);
779 		return (dr);
780 	}
781 
782 	/* entry does not exist */
783 	if (new->rtlifetime == 0) {
784 		/* flush all possible redirects */
785 		if (!ip6_forwarding && (new->ifp->if_xflags & IFXF_AUTOCONF6))
786 			rt6_flush(&new->rtaddr, new->ifp);
787 		splx(s);
788 		return (NULL);
789 	}
790 
791 	if (ip6_maxifdefrouters >= 0 &&
792 	    ext->ndefrouters >= ip6_maxifdefrouters) {
793 		splx(s);
794 		return (NULL);
795 	}
796 
797 	n = malloc(sizeof(*n), M_IP6NDP, M_NOWAIT | M_ZERO);
798 	if (n == NULL) {
799 		splx(s);
800 		return (NULL);
801 	}
802 	*n = *new;
803 
804 insert:
805 	/*
806 	 * Insert the new router in the Default Router List;
807 	 * The Default Router List should be in the descending order
808 	 * of router-preference.  Routers with the same preference are
809 	 * sorted in the arriving time order.
810 	 */
811 
812 	/* insert at the end of the group */
813 	TAILQ_FOREACH(dr, &nd_defrouter, dr_entry)
814 		if (rtpref(n) > rtpref(dr))
815 			break;
816 	if (dr)
817 		TAILQ_INSERT_BEFORE(dr, n, dr_entry);
818 	else
819 		TAILQ_INSERT_TAIL(&nd_defrouter, n, dr_entry);
820 
821 	defrouter_select();
822 
823 	ext->ndefrouters++;
824 
825 	splx(s);
826 
827 	return (n);
828 }
829 
830 struct nd_pfxrouter *
831 pfxrtr_lookup(struct nd_prefix *pr, struct nd_defrouter *dr)
832 {
833 	struct nd_pfxrouter *search;
834 
835 	LIST_FOREACH(search, &pr->ndpr_advrtrs, pfr_entry) {
836 		if (search->router == dr)
837 			break;
838 	}
839 
840 	return (search);
841 }
842 
843 void
844 pfxrtr_add(struct nd_prefix *pr, struct nd_defrouter *dr)
845 {
846 	struct nd_pfxrouter *new;
847 
848 	new = malloc(sizeof(*new), M_IP6NDP, M_NOWAIT | M_ZERO);
849 	if (new == NULL)
850 		return;
851 	new->router = dr;
852 
853 	LIST_INSERT_HEAD(&pr->ndpr_advrtrs, new, pfr_entry);
854 
855 	pfxlist_onlink_check();
856 }
857 
858 void
859 pfxrtr_del(struct nd_pfxrouter *pfr)
860 {
861 	LIST_REMOVE(pfr, pfr_entry);
862 	free(pfr, M_IP6NDP, 0);
863 }
864 
865 struct nd_prefix *
866 nd6_prefix_lookup(struct nd_prefix *pr)
867 {
868 	struct nd_prefix *search;
869 
870 	LIST_FOREACH(search, &nd_prefix, ndpr_entry) {
871 		if (pr->ndpr_ifp == search->ndpr_ifp &&
872 		    pr->ndpr_plen == search->ndpr_plen &&
873 		    in6_are_prefix_equal(&pr->ndpr_prefix.sin6_addr,
874 		    &search->ndpr_prefix.sin6_addr, pr->ndpr_plen)) {
875 			break;
876 		}
877 	}
878 
879 	return (search);
880 }
881 
882 void
883 purge_detached(struct ifnet *ifp)
884 {
885 	struct nd_prefix *pr, *pr_next;
886 	struct in6_ifaddr *ia6;
887 	struct ifaddr *ifa, *ifa_next;
888 
889 	LIST_FOREACH_SAFE(pr, &nd_prefix, ndpr_entry, pr_next) {
890 		/*
891 		 * This function is called when we need to make more room for
892 		 * new prefixes rather than keeping old, possibly stale ones.
893 		 * Detached prefixes would be a good candidate; if all routers
894 		 * that advertised the prefix expired, the prefix is also
895 		 * probably stale.
896 		 */
897 		if (pr->ndpr_ifp != ifp ||
898 		    IN6_IS_ADDR_LINKLOCAL(&pr->ndpr_prefix.sin6_addr) ||
899 		    ((pr->ndpr_stateflags & NDPRF_DETACHED) == 0 &&
900 		    !LIST_EMPTY(&pr->ndpr_advrtrs)))
901 			continue;
902 
903 		TAILQ_FOREACH_SAFE(ifa, &ifp->if_addrlist, ifa_list, ifa_next) {
904 			if (ifa->ifa_addr->sa_family != AF_INET6)
905 				continue;
906 			ia6 = ifatoia6(ifa);
907 			if ((ia6->ia6_flags & IN6_IFF_AUTOCONF) ==
908 			    IN6_IFF_AUTOCONF && ia6->ia6_ndpr == pr) {
909 				in6_purgeaddr(ifa);
910 			}
911 		}
912 	}
913 }
914 
915 int
916 nd6_prelist_add(struct nd_prefix *pr, struct nd_defrouter *dr,
917     struct nd_prefix **newp)
918 {
919 	struct nd_prefix *new = NULL;
920 	int i, s;
921 	struct in6_ifextra *ext = pr->ndpr_ifp->if_afdata[AF_INET6];
922 
923 	if (ip6_maxifprefixes >= 0) {
924 		if (ext->nprefixes >= ip6_maxifprefixes / 2)
925 			purge_detached(pr->ndpr_ifp);
926 		if (ext->nprefixes >= ip6_maxifprefixes)
927 			return(ENOMEM);
928 	}
929 
930 	new = malloc(sizeof(*new), M_IP6NDP, M_NOWAIT | M_ZERO);
931 	if (new == NULL)
932 		return ENOMEM;
933 	*new = *pr;
934 	if (newp != NULL)
935 		*newp = new;
936 
937 	/* initialization */
938 	LIST_INIT(&new->ndpr_advrtrs);
939 	in6_prefixlen2mask(&new->ndpr_mask, new->ndpr_plen);
940 	/* make prefix in the canonical form */
941 	for (i = 0; i < 4; i++)
942 		new->ndpr_prefix.sin6_addr.s6_addr32[i] &=
943 		    new->ndpr_mask.s6_addr32[i];
944 
945 	task_set(&new->ndpr_task, nd6_addr_add, new, NULL);
946 
947 	s = splsoftnet();
948 	/* link ndpr_entry to nd_prefix list */
949 	LIST_INSERT_HEAD(&nd_prefix, new, ndpr_entry);
950 	splx(s);
951 
952 	/* ND_OPT_PI_FLAG_ONLINK processing */
953 	if (new->ndpr_raf_onlink) {
954 		char addr[INET6_ADDRSTRLEN];
955 		int e;
956 
957 		if ((e = nd6_prefix_onlink(new)) != 0) {
958 			nd6log((LOG_ERR, "nd6_prelist_add: failed to make "
959 			    "the prefix %s/%d on-link on %s (errno=%d)\n",
960 			    inet_ntop(AF_INET6, &pr->ndpr_prefix.sin6_addr,
961 				addr, sizeof(addr)),
962 			    pr->ndpr_plen, pr->ndpr_ifp->if_xname, e));
963 			/* proceed anyway. XXX: is it correct? */
964 		}
965 	}
966 
967 	if (dr)
968 		pfxrtr_add(new, dr);
969 
970 	ext->nprefixes++;
971 
972 	return 0;
973 }
974 
975 void
976 prelist_remove(struct nd_prefix *pr)
977 {
978 	struct nd_pfxrouter *pfr, *next;
979 	int e, s;
980 	struct in6_ifextra *ext = pr->ndpr_ifp->if_afdata[AF_INET6];
981 
982 	/* make sure to invalidate the prefix until it is really freed. */
983 	pr->ndpr_vltime = 0;
984 	pr->ndpr_pltime = 0;
985 #if 0
986 	/*
987 	 * Though these flags are now meaningless, we'd rather keep the value
988 	 * not to confuse users when executing "ndp -p".
989 	 */
990 	pr->ndpr_raf_onlink = 0;
991 	pr->ndpr_raf_auto = 0;
992 #endif
993 	if ((pr->ndpr_stateflags & NDPRF_ONLINK) != 0 &&
994 	    (e = nd6_prefix_offlink(pr)) != 0) {
995 		char addr[INET6_ADDRSTRLEN];
996 		nd6log((LOG_ERR, "prelist_remove: failed to make %s/%d offlink "
997 		    "on %s, errno=%d\n",
998 		    inet_ntop(AF_INET6, &pr->ndpr_prefix.sin6_addr,
999 			addr, sizeof(addr)),
1000 		    pr->ndpr_plen, pr->ndpr_ifp->if_xname, e));
1001 		/* what should we do? */
1002 	}
1003 
1004 	if (pr->ndpr_refcnt > 0)
1005 		return;		/* notice here? */
1006 
1007 	s = splsoftnet();
1008 
1009 	/* unlink ndpr_entry from nd_prefix list */
1010 	LIST_REMOVE(pr, ndpr_entry);
1011 
1012 	/* free list of routers that adversed the prefix */
1013 	LIST_FOREACH_SAFE(pfr, &pr->ndpr_advrtrs, pfr_entry, next)
1014 		free(pfr, M_IP6NDP, 0);
1015 
1016 	ext->nprefixes--;
1017 	if (ext->nprefixes < 0) {
1018 		log(LOG_WARNING, "prelist_remove: negative count on %s\n",
1019 		    pr->ndpr_ifp->if_xname);
1020 	}
1021 	splx(s);
1022 
1023 	free(pr, M_IP6NDP, 0);
1024 
1025 	pfxlist_onlink_check();
1026 }
1027 
1028 /*
1029  * dr - may be NULL
1030  */
1031 
1032 int
1033 prelist_update(struct nd_prefix *new, struct nd_defrouter *dr, struct mbuf *m)
1034 {
1035 	struct in6_ifaddr *ia6_match = NULL;
1036 	struct ifaddr *ifa;
1037 	struct ifnet *ifp = new->ndpr_ifp;
1038 	struct nd_prefix *pr;
1039 	int s = splsoftnet();
1040 	int error = 0;
1041 	int tempaddr_preferred = 0, autoconf = 0, statique = 0;
1042 	int auth;
1043 	struct in6_addrlifetime lt6_tmp;
1044 	char addr[INET6_ADDRSTRLEN];
1045 
1046 	auth = 0;
1047 	if (m) {
1048 		/*
1049 		 * Authenticity for NA consists authentication for
1050 		 * both IP header and IP datagrams, doesn't it ?
1051 		 */
1052 		auth = (m->m_flags & M_AUTH);
1053 	}
1054 
1055 	if ((pr = nd6_prefix_lookup(new)) != NULL) {
1056 		/*
1057 		 * nd6_prefix_lookup() ensures that pr and new have the same
1058 		 * prefix on a same interface.
1059 		 */
1060 
1061 		/*
1062 		 * Update prefix information.  Note that the on-link (L) bit
1063 		 * and the autonomous (A) bit should NOT be changed from 1
1064 		 * to 0.
1065 		 */
1066 		if (new->ndpr_raf_onlink == 1)
1067 			pr->ndpr_raf_onlink = 1;
1068 		if (new->ndpr_raf_auto == 1)
1069 			pr->ndpr_raf_auto = 1;
1070 		if (new->ndpr_raf_onlink) {
1071 			pr->ndpr_vltime = new->ndpr_vltime;
1072 			pr->ndpr_pltime = new->ndpr_pltime;
1073 			pr->ndpr_preferred = new->ndpr_preferred;
1074 			pr->ndpr_expire = new->ndpr_expire;
1075 			pr->ndpr_lastupdate = new->ndpr_lastupdate;
1076 		}
1077 
1078 		if (new->ndpr_raf_onlink &&
1079 		    (pr->ndpr_stateflags & NDPRF_ONLINK) == 0) {
1080 			int e;
1081 
1082 			if ((e = nd6_prefix_onlink(pr)) != 0) {
1083 				nd6log((LOG_ERR,
1084 				    "prelist_update: failed to make "
1085 				    "the prefix %s/%d on-link on %s "
1086 				    "(errno=%d)\n",
1087 				    inet_ntop(AF_INET6,
1088 					&pr->ndpr_prefix.sin6_addr,
1089 					addr, sizeof(addr)),
1090 				    pr->ndpr_plen, pr->ndpr_ifp->if_xname, e));
1091 				/* proceed anyway. XXX: is it correct? */
1092 			}
1093 		}
1094 
1095 		if (dr && pfxrtr_lookup(pr, dr) == NULL)
1096 			pfxrtr_add(pr, dr);
1097 	} else {
1098 		struct nd_prefix *newpr = NULL;
1099 
1100 		if (new->ndpr_vltime == 0)
1101 			goto end;
1102 		if (new->ndpr_raf_onlink == 0 && new->ndpr_raf_auto == 0)
1103 			goto end;
1104 
1105 		error = nd6_prelist_add(new, dr, &newpr);
1106 		if (error != 0 || newpr == NULL) {
1107 			nd6log((LOG_NOTICE, "prelist_update: "
1108 			    "nd6_prelist_add failed for %s/%d on %s "
1109 			    "errno=%d, returnpr=%p\n",
1110 			    inet_ntop(AF_INET6, &new->ndpr_prefix.sin6_addr,
1111 				addr, sizeof(addr)),
1112 			    new->ndpr_plen, new->ndpr_ifp->if_xname,
1113 			    error, newpr));
1114 			goto end; /* we should just give up in this case. */
1115 		}
1116 
1117 		/*
1118 		 * XXX: from the ND point of view, we can ignore a prefix
1119 		 * with the on-link bit being zero.  However, we need a
1120 		 * prefix structure for references from autoconfigured
1121 		 * addresses.  Thus, we explicitly make sure that the prefix
1122 		 * itself expires now.
1123 		 */
1124 		if (newpr->ndpr_raf_onlink == 0) {
1125 			newpr->ndpr_vltime = 0;
1126 			newpr->ndpr_pltime = 0;
1127 			in6_init_prefix_ltimes(newpr);
1128 		}
1129 
1130 		pr = newpr;
1131 	}
1132 
1133 	/*
1134 	 * Address autoconfiguration based on Section 5.5.3 of RFC 2462.
1135 	 * Note that pr must be non NULL at this point.
1136 	 */
1137 
1138 	/* 5.5.3 (a). Ignore the prefix without the A bit set. */
1139 	if (!new->ndpr_raf_auto)
1140 		goto end;
1141 
1142 	/*
1143 	 * 5.5.3 (b). the link-local prefix should have been ignored in
1144 	 * nd6_ra_input.
1145 	 */
1146 
1147 	/*
1148 	 * 5.5.3 (c). Consistency check on lifetimes: pltime <= vltime.
1149 	 * This should have been done in nd6_ra_input.
1150 	 */
1151 
1152 	/*
1153 	 * 5.5.3 (d). If the prefix advertised does not match the prefix of an
1154 	 * address already in the list, and the Valid Lifetime is not 0,
1155 	 * form an address.  Note that even a manually configured address
1156 	 * should reject autoconfiguration of a new address.
1157 	 */
1158 	TAILQ_FOREACH(ifa, &ifp->if_addrlist, ifa_list) {
1159 		struct in6_ifaddr *ia6;
1160 		int ifa_plen;
1161 		u_int32_t storedlifetime;
1162 
1163 		if (ifa->ifa_addr->sa_family != AF_INET6)
1164 			continue;
1165 
1166 		ia6 = ifatoia6(ifa);
1167 
1168 		/*
1169 		 * Spec is not clear here, but I believe we should concentrate
1170 		 * on unicast (i.e. not anycast) addresses.
1171 		 * XXX: other ia6_flags? detached or duplicated?
1172 		 */
1173 		if ((ia6->ia6_flags & IN6_IFF_ANYCAST) != 0)
1174 			continue;
1175 
1176 		ifa_plen = in6_mask2len(&ia6->ia_prefixmask.sin6_addr, NULL);
1177 		if (ifa_plen != new->ndpr_plen ||
1178 		    !in6_are_prefix_equal(&ia6->ia_addr.sin6_addr,
1179 		    &new->ndpr_prefix.sin6_addr, ifa_plen))
1180 			continue;
1181 
1182 		if (ia6_match == NULL) /* remember the first one */
1183 			ia6_match = ia6;
1184 
1185 		if ((ia6->ia6_flags & IN6_IFF_AUTOCONF) == 0) {
1186 			statique = 1;
1187 			continue;
1188 		}
1189 
1190 		/*
1191 		 * An already autoconfigured address matched.  Now that we
1192 		 * are sure there is at least one matched address, we can
1193 		 * proceed to 5.5.3. (e): update the lifetimes according to the
1194 		 * "two hours" rule and the privacy extension.
1195 		 */
1196 #define TWOHOUR		(120*60)
1197 		/*
1198 		 * RFC2462 introduces the notion of StoredLifetime to the
1199 		 * "two hours" rule as follows:
1200 		 *   the Lifetime associated with the previously autoconfigured
1201 		 *   address.
1202 		 * Our interpretation of this definition is "the remaining
1203 		 * lifetime to expiration at the evaluation time".  One might
1204 		 * be wondering if this interpretation is really conform to the
1205 		 * RFC, because the text can read that "Lifetimes" are never
1206 		 * decreased, and our definition of the "storedlifetime" below
1207 		 * essentially reduces the "Valid Lifetime" advertised in the
1208 		 * previous RA.  But, this is due to the wording of the text,
1209 		 * and our interpretation is the same as an author's intention.
1210 		 * See the discussion in the IETF ipngwg ML in August 2001,
1211 		 * with the Subject "StoredLifetime in RFC 2462".
1212 		 */
1213 		lt6_tmp = ia6->ia6_lifetime;
1214 
1215 		/* RFC 4941 temporary addresses (privacy extension). */
1216 		if (ia6->ia6_flags & IN6_IFF_PRIVACY) {
1217 			/* Do we still have a non-deprecated address? */
1218 			if ((ia6->ia6_flags & IN6_IFF_DEPRECATED) == 0)
1219 				tempaddr_preferred = 1;
1220 			/* Don't extend lifetime for temporary addresses. */
1221 			if (new->ndpr_vltime >= lt6_tmp.ia6t_vltime)
1222 				continue;
1223 			if (new->ndpr_pltime >= lt6_tmp.ia6t_pltime)
1224 				continue;
1225 		} else if ((ia6->ia6_flags & IN6_IFF_DEPRECATED) == 0)
1226 			/* We have a regular SLAAC address. */
1227 			autoconf = 1;
1228 
1229 		if (lt6_tmp.ia6t_vltime == ND6_INFINITE_LIFETIME)
1230 			storedlifetime = ND6_INFINITE_LIFETIME;
1231 		else if (time_second - ia6->ia6_updatetime >
1232 			 lt6_tmp.ia6t_vltime) {
1233 			/*
1234 			 * The case of "invalid" address.  We should usually
1235 			 * not see this case.
1236 			 */
1237 			storedlifetime = 0;
1238 		} else
1239 			storedlifetime = lt6_tmp.ia6t_vltime -
1240 				(time_second - ia6->ia6_updatetime);
1241 		if (TWOHOUR < new->ndpr_vltime ||
1242 		    storedlifetime < new->ndpr_vltime) {
1243 			lt6_tmp.ia6t_vltime = new->ndpr_vltime;
1244 		} else if (storedlifetime <= TWOHOUR
1245 #if 0
1246 			   /*
1247 			    * This condition is logically redundant, so we just
1248 			    * omit it.
1249 			    * See IPng 6712, 6717, and 6721.
1250 			    */
1251 			   && new->ndpr_vltime <= storedlifetime
1252 #endif
1253 			) {
1254 			if (auth) {
1255 				lt6_tmp.ia6t_vltime = new->ndpr_vltime;
1256 			}
1257 		} else {
1258 			/*
1259 			 * new->ndpr_vltime <= TWOHOUR &&
1260 			 * TWOHOUR < storedlifetime
1261 			 */
1262 			lt6_tmp.ia6t_vltime = TWOHOUR;
1263 		}
1264 
1265 		/* The 2 hour rule is not imposed for preferred lifetime. */
1266 		lt6_tmp.ia6t_pltime = new->ndpr_pltime;
1267 
1268 		in6_init_address_ltimes(pr, &lt6_tmp);
1269 
1270 		ia6->ia6_lifetime = lt6_tmp;
1271 		ia6->ia6_updatetime = time_second;
1272 	}
1273 
1274 	if ((!autoconf || ((ifp->if_xflags & IFXF_INET6_NOPRIVACY) == 0 &&
1275 	    !tempaddr_preferred)) && new->ndpr_vltime != 0 &&
1276 	    !((ifp->if_xflags & IFXF_INET6_NOPRIVACY) && statique)) {
1277 		/*
1278 		 * There is no SLAAC address and/or there is no preferred RFC
1279 		 * 4941 temporary address. And the valid prefix lifetime is
1280 		 * non-zero. And there is no static address in the same prefix.
1281 		 * Create new addresses in process context.
1282 		 * Increment prefix refcount to ensure the prefix is not
1283 		 * removed before the task is done.
1284 		 */
1285 		pr->ndpr_refcnt++;
1286 		if (task_add(systq, &pr->ndpr_task) == 0)
1287 			pr->ndpr_refcnt--;
1288 	}
1289 
1290  end:
1291 	splx(s);
1292 	return error;
1293 }
1294 
1295 void
1296 nd6_addr_add(void *prptr, void *arg2)
1297 {
1298 	struct nd_prefix *pr = (struct nd_prefix *)prptr;
1299 	struct in6_ifaddr *ia6 = NULL;
1300 	int autoconf, privacy, s;
1301 
1302 	s = splsoftnet();
1303 
1304 	autoconf = 1;
1305 	privacy = (pr->ndpr_ifp->if_xflags & IFXF_INET6_NOPRIVACY) == 0;
1306 
1307 	if (autoconf && (ia6 = in6_ifadd(pr, 0)) != NULL) {
1308 		ia6->ia6_ndpr = pr;
1309 		pr->ndpr_refcnt++;
1310 	} else
1311 		autoconf = 0;
1312 
1313 	if (privacy && (ia6 = in6_ifadd(pr, 1)) != NULL) {
1314 		ia6->ia6_ndpr = pr;
1315 		pr->ndpr_refcnt++;
1316 	} else
1317 		privacy = 0;
1318 
1319 	/*
1320 	 * A newly added address might affect the status
1321 	 * of other addresses, so we check and update it.
1322 	 * XXX: what if address duplication happens?
1323 	 */
1324 	if (autoconf || privacy)
1325 		pfxlist_onlink_check();
1326 
1327 	/* Decrement prefix refcount now that the task is done. */
1328 	pr->ndpr_refcnt--;
1329 
1330 	splx(s);
1331 }
1332 
1333 /*
1334  * A supplement function used in the on-link detection below;
1335  * detect if a given prefix has a (probably) reachable advertising router.
1336  * XXX: lengthy function name...
1337  */
1338 struct nd_pfxrouter *
1339 find_pfxlist_reachable_router(struct nd_prefix *pr)
1340 {
1341 	struct nd_pfxrouter *pfxrtr;
1342 	struct rtentry *rt;
1343 	struct llinfo_nd6 *ln;
1344 
1345 	LIST_FOREACH(pfxrtr, &pr->ndpr_advrtrs, pfr_entry) {
1346 		if ((rt = nd6_lookup(&pfxrtr->router->rtaddr, 0,
1347 		    pfxrtr->router->ifp, pfxrtr->router->ifp->if_rdomain)) &&
1348 		    (ln = (struct llinfo_nd6 *)rt->rt_llinfo) &&
1349 		    ND6_IS_LLINFO_PROBREACH(ln))
1350 			break;	/* found */
1351 	}
1352 
1353 	return (pfxrtr);
1354 }
1355 
1356 /*
1357  * Check if each prefix in the prefix list has at least one available router
1358  * that advertised the prefix (a router is "available" if its neighbor cache
1359  * entry is reachable or probably reachable).
1360  * If the check fails, the prefix may be off-link, because, for example,
1361  * we have moved from the network but the lifetime of the prefix has not
1362  * expired yet.  So we should not use the prefix if there is another prefix
1363  * that has an available router.
1364  * But, if there is no prefix that has an available router, we still regards
1365  * all the prefixes as on-link.  This is because we can't tell if all the
1366  * routers are simply dead or if we really moved from the network and there
1367  * is no router around us.
1368  */
1369 void
1370 pfxlist_onlink_check(void)
1371 {
1372 	struct nd_prefix *pr;
1373 	struct in6_ifaddr *ia6;
1374 	char addr[INET6_ADDRSTRLEN];
1375 
1376 	/*
1377 	 * Check if there is a prefix that has a reachable advertising
1378 	 * router.
1379 	 */
1380 	LIST_FOREACH(pr, &nd_prefix, ndpr_entry) {
1381 		if (pr->ndpr_raf_onlink && find_pfxlist_reachable_router(pr))
1382 			break;
1383 	}
1384 	if (pr != NULL || !TAILQ_EMPTY(&nd_defrouter)) {
1385 		/*
1386 		 * There is at least one prefix that has a reachable router,
1387 		 * or at least a router which probably does not advertise
1388 		 * any prefixes.  The latter would be the case when we move
1389 		 * to a new link where we have a router that does not provide
1390 		 * prefixes and we configure an address by hand.
1391 		 * Detach prefixes which have no reachable advertising
1392 		 * router, and attach other prefixes.
1393 		 */
1394 		LIST_FOREACH(pr, &nd_prefix, ndpr_entry) {
1395 			/* XXX: a link-local prefix should never be detached */
1396 			if (IN6_IS_ADDR_LINKLOCAL(&pr->ndpr_prefix.sin6_addr))
1397 				continue;
1398 
1399 			/*
1400 			 * we aren't interested in prefixes without the L bit
1401 			 * set.
1402 			 */
1403 			if (pr->ndpr_raf_onlink == 0)
1404 				continue;
1405 
1406 			if ((pr->ndpr_stateflags & NDPRF_DETACHED) == 0 &&
1407 			    find_pfxlist_reachable_router(pr) == NULL)
1408 				pr->ndpr_stateflags |= NDPRF_DETACHED;
1409 			if ((pr->ndpr_stateflags & NDPRF_DETACHED) != 0 &&
1410 			    find_pfxlist_reachable_router(pr) != 0)
1411 				pr->ndpr_stateflags &= ~NDPRF_DETACHED;
1412 		}
1413 	} else {
1414 		/* there is no prefix that has a reachable router */
1415 		LIST_FOREACH(pr, &nd_prefix, ndpr_entry) {
1416 			if (IN6_IS_ADDR_LINKLOCAL(&pr->ndpr_prefix.sin6_addr))
1417 				continue;
1418 
1419 			if (pr->ndpr_raf_onlink == 0)
1420 				continue;
1421 
1422 			if ((pr->ndpr_stateflags & NDPRF_DETACHED) != 0)
1423 				pr->ndpr_stateflags &= ~NDPRF_DETACHED;
1424 		}
1425 	}
1426 
1427 	/*
1428 	 * Remove each interface route associated with a (just) detached
1429 	 * prefix, and reinstall the interface route for a (just) attached
1430 	 * prefix.  Note that all attempt of reinstallation does not
1431 	 * necessarily success, when a same prefix is shared among multiple
1432 	 * interfaces.  Such cases will be handled in nd6_prefix_onlink,
1433 	 * so we don't have to care about them.
1434 	 */
1435 	LIST_FOREACH(pr, &nd_prefix, ndpr_entry) {
1436 		int e;
1437 
1438 		if (IN6_IS_ADDR_LINKLOCAL(&pr->ndpr_prefix.sin6_addr))
1439 			continue;
1440 
1441 		if (pr->ndpr_raf_onlink == 0)
1442 			continue;
1443 
1444 		if ((pr->ndpr_stateflags & NDPRF_DETACHED) != 0 &&
1445 		    (pr->ndpr_stateflags & NDPRF_ONLINK) != 0) {
1446 			if ((e = nd6_prefix_offlink(pr)) != 0) {
1447 				nd6log((LOG_ERR,
1448 				    "pfxlist_onlink_check: failed to "
1449 				    "make %s/%d offlink, errno=%d\n",
1450 				    inet_ntop(AF_INET6,
1451 					&pr->ndpr_prefix.sin6_addr,
1452 					addr, sizeof(addr)),
1453 				    pr->ndpr_plen, e));
1454 			}
1455 		}
1456 		if ((pr->ndpr_stateflags & NDPRF_DETACHED) == 0 &&
1457 		    (pr->ndpr_stateflags & NDPRF_ONLINK) == 0 &&
1458 		    pr->ndpr_raf_onlink) {
1459 			if ((e = nd6_prefix_onlink(pr)) != 0) {
1460 				nd6log((LOG_ERR,
1461 				    "pfxlist_onlink_check: failed to "
1462 				    "make %s/%d offlink, errno=%d\n",
1463 				    inet_ntop(AF_INET6,
1464 					&pr->ndpr_prefix.sin6_addr,
1465 					addr, sizeof(addr)),
1466 				    pr->ndpr_plen, e));
1467 			}
1468 		}
1469 	}
1470 
1471 	/*
1472 	 * Changes on the prefix status might affect address status as well.
1473 	 * Make sure that all addresses derived from an attached prefix are
1474 	 * attached, and that all addresses derived from a detached prefix are
1475 	 * detached.  Note, however, that a manually configured address should
1476 	 * always be attached.
1477 	 * The precise detection logic is same as the one for prefixes.
1478 	 */
1479 	TAILQ_FOREACH(ia6, &in6_ifaddr, ia_list) {
1480 		if (!(ia6->ia6_flags & IN6_IFF_AUTOCONF))
1481 			continue;
1482 
1483 		if (ia6->ia6_ndpr == NULL) {
1484 			/*
1485 			 * This can happen when we first configure the address
1486 			 * (i.e. the address exists, but the prefix does not).
1487 			 * XXX: complicated relationships...
1488 			 */
1489 			continue;
1490 		}
1491 
1492 		if (find_pfxlist_reachable_router(ia6->ia6_ndpr))
1493 			break;
1494 	}
1495 	if (ia6) {
1496 		TAILQ_FOREACH(ia6, &in6_ifaddr, ia_list) {
1497 			if ((ia6->ia6_flags & IN6_IFF_AUTOCONF) == 0)
1498 				continue;
1499 
1500 			if (ia6->ia6_ndpr == NULL) /* XXX: see above. */
1501 				continue;
1502 
1503 			if (find_pfxlist_reachable_router(ia6->ia6_ndpr))
1504 				ia6->ia6_flags &= ~IN6_IFF_DETACHED;
1505 			else
1506 				ia6->ia6_flags |= IN6_IFF_DETACHED;
1507 		}
1508 	}
1509 	else {
1510 		TAILQ_FOREACH(ia6, &in6_ifaddr, ia_list) {
1511 			if ((ia6->ia6_flags & IN6_IFF_AUTOCONF) == 0)
1512 				continue;
1513 
1514 			ia6->ia6_flags &= ~IN6_IFF_DETACHED;
1515 		}
1516 	}
1517 }
1518 
1519 int
1520 nd6_prefix_onlink(struct nd_prefix *pr)
1521 {
1522 	struct rt_addrinfo info;
1523 	struct ifaddr *ifa;
1524 	struct ifnet *ifp = pr->ndpr_ifp;
1525 	struct sockaddr_in6 mask6;
1526 	struct nd_prefix *opr;
1527 	u_long rtflags;
1528 	int error = 0;
1529 	struct rtentry *rt = NULL;
1530 	char addr[INET6_ADDRSTRLEN];
1531 
1532 	/* sanity check */
1533 	if ((pr->ndpr_stateflags & NDPRF_ONLINK) != 0) {
1534 		nd6log((LOG_ERR,
1535 		    "nd6_prefix_onlink: %s/%d is already on-link\n",
1536 		    inet_ntop(AF_INET6,	&pr->ndpr_prefix.sin6_addr,
1537 			addr, sizeof(addr)),
1538 		    pr->ndpr_plen));
1539 		return (EEXIST);
1540 	}
1541 
1542 	/*
1543 	 * Add the interface route associated with the prefix.  Before
1544 	 * installing the route, check if there's the same prefix on another
1545 	 * interface, and the prefix has already installed the interface route.
1546 	 * Although such a configuration is expected to be rare, we explicitly
1547 	 * allow it.
1548 	 */
1549 	LIST_FOREACH(opr, &nd_prefix, ndpr_entry) {
1550 		if (opr == pr)
1551 			continue;
1552 
1553 		if ((opr->ndpr_stateflags & NDPRF_ONLINK) == 0)
1554 			continue;
1555 
1556 		if (opr->ndpr_plen == pr->ndpr_plen &&
1557 		    in6_are_prefix_equal(&pr->ndpr_prefix.sin6_addr,
1558 		    &opr->ndpr_prefix.sin6_addr, pr->ndpr_plen))
1559 			return (0);
1560 	}
1561 
1562 	/*
1563 	 * We prefer link-local addresses as the associated interface address.
1564 	 */
1565 	/* search for a link-local addr */
1566 	ifa = &in6ifa_ifpforlinklocal(ifp,
1567 	    IN6_IFF_NOTREADY | IN6_IFF_ANYCAST)->ia_ifa;
1568 	if (ifa == NULL) {
1569 		TAILQ_FOREACH(ifa, &ifp->if_addrlist, ifa_list) {
1570 			if (ifa->ifa_addr->sa_family == AF_INET6)
1571 				break;
1572 		}
1573 		/* should we care about ia6_flags? */
1574 	}
1575 	if (ifa == NULL) {
1576 		/*
1577 		 * This can still happen, when, for example, we receive an RA
1578 		 * containing a prefix with the L bit set and the A bit clear,
1579 		 * after removing all IPv6 addresses on the receiving
1580 		 * interface.  This should, of course, be rare though.
1581 		 */
1582 		nd6log((LOG_NOTICE,
1583 		    "nd6_prefix_onlink: failed to find any ifaddr"
1584 		    " to add route for a prefix(%s/%d) on %s\n",
1585 		    inet_ntop(AF_INET6,	&pr->ndpr_prefix.sin6_addr,
1586 			addr, sizeof(addr)),
1587 		    pr->ndpr_plen, ifp->if_xname));
1588 		return (0);
1589 	}
1590 
1591 	/*
1592 	 * in6_ifinit() sets nd6_rtrequest to ifa_rtrequest for all ifaddrs.
1593 	 * ifa->ifa_rtrequest = nd6_rtrequest;
1594 	 */
1595 	bzero(&mask6, sizeof(mask6));
1596 	mask6.sin6_len = sizeof(mask6);
1597 	mask6.sin6_addr = pr->ndpr_mask;
1598 	/* rtrequest1() will probably set RTF_UP, but we're not sure. */
1599 	rtflags = RTF_UP;
1600 	if (nd6_need_cache(ifp))
1601 		rtflags |= RTF_CLONING;
1602 	else
1603 		rtflags &= ~RTF_CLONING;
1604 
1605 	bzero(&info, sizeof(info));
1606 	info.rti_flags = rtflags;
1607 	info.rti_info[RTAX_DST] = sin6tosa(&pr->ndpr_prefix);
1608 	info.rti_info[RTAX_GATEWAY] = ifa->ifa_addr;
1609 	info.rti_info[RTAX_NETMASK] = sin6tosa(&mask6);
1610 
1611 	error = rtrequest1(RTM_ADD, &info, RTP_CONNECTED, &rt, ifp->if_rdomain);
1612 	if (error == 0) {
1613 		if (rt != NULL) /* this should be non NULL, though */
1614 			rt_sendmsg(rt, RTM_ADD, ifp->if_rdomain);
1615 		pr->ndpr_stateflags |= NDPRF_ONLINK;
1616 	} else {
1617 		char gw[INET6_ADDRSTRLEN], mask[INET6_ADDRSTRLEN];
1618 		nd6log((LOG_ERR, "nd6_prefix_onlink: failed to add route for a"
1619 		    " prefix (%s/%d) on %s, gw=%s, mask=%s, flags=%lx "
1620 		    "errno = %d\n",
1621 		    inet_ntop(AF_INET6,	&pr->ndpr_prefix.sin6_addr,
1622 			addr, sizeof(addr)),
1623 		    pr->ndpr_plen, ifp->if_xname,
1624 		    inet_ntop(AF_INET6, &satosin6(ifa->ifa_addr)->sin6_addr,
1625 			gw, sizeof(gw)),
1626 		    inet_ntop(AF_INET6, &mask6.sin6_addr, mask, sizeof(mask)),
1627 		    rtflags, error));
1628 	}
1629 
1630 	if (rt != NULL)
1631 		rt->rt_refcnt--;
1632 
1633 	return (error);
1634 }
1635 
1636 int
1637 nd6_prefix_offlink(struct nd_prefix *pr)
1638 {
1639 	struct rt_addrinfo info;
1640 	int error = 0;
1641 	struct ifnet *ifp = pr->ndpr_ifp;
1642 	struct nd_prefix *opr;
1643 	struct sockaddr_in6 sa6, mask6;
1644 	struct rtentry *rt = NULL;
1645 	char addr[INET6_ADDRSTRLEN];
1646 
1647 	/* sanity check */
1648 	if ((pr->ndpr_stateflags & NDPRF_ONLINK) == 0) {
1649 		nd6log((LOG_ERR,
1650 		    "nd6_prefix_offlink: %s/%d is already off-link\n",
1651 		    inet_ntop(AF_INET6, &pr->ndpr_prefix.sin6_addr,
1652 			addr, sizeof(addr)),
1653 		    pr->ndpr_plen));
1654 		return (EEXIST);
1655 	}
1656 
1657 	bzero(&sa6, sizeof(sa6));
1658 	sa6.sin6_family = AF_INET6;
1659 	sa6.sin6_len = sizeof(sa6);
1660 	bcopy(&pr->ndpr_prefix.sin6_addr, &sa6.sin6_addr,
1661 	    sizeof(struct in6_addr));
1662 	bzero(&mask6, sizeof(mask6));
1663 	mask6.sin6_family = AF_INET6;
1664 	mask6.sin6_len = sizeof(sa6);
1665 	bcopy(&pr->ndpr_mask, &mask6.sin6_addr, sizeof(struct in6_addr));
1666 	bzero(&info, sizeof(info));
1667 	info.rti_info[RTAX_DST] = sin6tosa(&sa6);
1668 	info.rti_info[RTAX_NETMASK] = sin6tosa(&mask6);
1669 	error = rtrequest1(RTM_DELETE, &info, RTP_CONNECTED, &rt,
1670 	    ifp->if_rdomain);
1671 	if (error == 0) {
1672 		pr->ndpr_stateflags &= ~NDPRF_ONLINK;
1673 
1674 		/* report the route deletion to the routing socket. */
1675 		if (rt != NULL)
1676 			rt_sendmsg(rt, RTM_DELETE, ifp->if_rdomain);
1677 
1678 		/*
1679 		 * There might be the same prefix on another interface,
1680 		 * the prefix which could not be on-link just because we have
1681 		 * the interface route (see comments in nd6_prefix_onlink).
1682 		 * If there's one, try to make the prefix on-link on the
1683 		 * interface.
1684 		 */
1685 		LIST_FOREACH(opr, &nd_prefix, ndpr_entry) {
1686 			if (opr == pr)
1687 				continue;
1688 
1689 			if ((opr->ndpr_stateflags & NDPRF_ONLINK) != 0)
1690 				continue;
1691 
1692 			/*
1693 			 * KAME specific: detached prefixes should not be
1694 			 * on-link.
1695 			 */
1696 			if ((opr->ndpr_stateflags & NDPRF_DETACHED) != 0)
1697 				continue;
1698 
1699 			if (opr->ndpr_plen == pr->ndpr_plen &&
1700 			    in6_are_prefix_equal(&pr->ndpr_prefix.sin6_addr,
1701 			    &opr->ndpr_prefix.sin6_addr, pr->ndpr_plen)) {
1702 				int e;
1703 
1704 				if ((e = nd6_prefix_onlink(opr)) != 0) {
1705 					nd6log((LOG_ERR,
1706 					    "nd6_prefix_offlink: failed to "
1707 					    "recover a prefix %s/%d from %s "
1708 					    "to %s (errno = %d)\n",
1709 					    inet_ntop(AF_INET6,
1710 						&pr->ndpr_prefix.sin6_addr,
1711 						addr, sizeof(addr)),
1712 					    opr->ndpr_plen, ifp->if_xname,
1713 					    opr->ndpr_ifp->if_xname, e));
1714 				}
1715 			}
1716 		}
1717 	} else {
1718 		/* XXX: can we still set the NDPRF_ONLINK flag? */
1719 		nd6log((LOG_ERR,
1720 		    "nd6_prefix_offlink: failed to delete route: "
1721 		    "%s/%d on %s (errno = %d)\n",
1722 		    inet_ntop(AF_INET6,	&sa6.sin6_addr, addr, sizeof(addr)),
1723 		    pr->ndpr_plen, ifp->if_xname, error));
1724 	}
1725 
1726 	if (rt != NULL) {
1727 		if (rt->rt_refcnt <= 0) {
1728 			/* XXX: we should free the entry ourselves. */
1729 			rt->rt_refcnt++;
1730 			rtfree(rt);
1731 		}
1732 	}
1733 
1734 	return (error);
1735 }
1736 
1737 struct in6_ifaddr *
1738 in6_ifadd(struct nd_prefix *pr, int privacy)
1739 {
1740 	struct ifnet *ifp = pr->ndpr_ifp;
1741 	struct ifaddr *ifa;
1742 	struct in6_aliasreq ifra;
1743 	struct in6_ifaddr *ia6;
1744 	int error, s, plen0;
1745 	struct in6_addr mask, rand_ifid;
1746 	int prefixlen = pr->ndpr_plen;
1747 
1748 	in6_prefixlen2mask(&mask, prefixlen);
1749 
1750 	/*
1751 	 * find a link-local address (will be interface ID).
1752 	 * Is it really mandatory? Theoretically, a global or a site-local
1753 	 * address can be configured without a link-local address, if we
1754 	 * have a unique interface identifier...
1755 	 *
1756 	 * it is not mandatory to have a link-local address, we can generate
1757 	 * interface identifier on the fly.  we do this because:
1758 	 * (1) it should be the easiest way to find interface identifier.
1759 	 * (2) RFC2462 5.4 suggesting the use of the same interface identifier
1760 	 * for multiple addresses on a single interface, and possible shortcut
1761 	 * of DAD.  we omitted DAD for this reason in the past.
1762 	 * (3) a user can prevent autoconfiguration of global address
1763 	 * by removing link-local address by hand (this is partly because we
1764 	 * don't have other way to control the use of IPv6 on a interface.
1765 	 * this has been our design choice - cf. NRL's "ifconfig auto").
1766 	 * (4) it is easier to manage when an interface has addresses
1767 	 * with the same interface identifier, than to have multiple addresses
1768 	 * with different interface identifiers.
1769 	 */
1770 	ifa = &in6ifa_ifpforlinklocal(ifp, 0)->ia_ifa; /* 0 is OK? */
1771 	if (ifa)
1772 		ia6 = ifatoia6(ifa);
1773 	else
1774 		return NULL;
1775 
1776 #if 0 /* don't care link local addr state, and always do DAD */
1777 	/* if link-local address is not eligible, do not autoconfigure. */
1778 	if (ifatoia6(ifa)->ia6_flags & IN6_IFF_NOTREADY) {
1779 		printf("in6_ifadd: link-local address not ready\n");
1780 		return NULL;
1781 	}
1782 #endif
1783 
1784 	/* prefixlen + ifidlen must be equal to 128 */
1785 	plen0 = in6_mask2len(&ia6->ia_prefixmask.sin6_addr, NULL);
1786 	if (prefixlen != plen0) {
1787 		nd6log((LOG_INFO, "in6_ifadd: wrong prefixlen for %s "
1788 		    "(prefix=%d ifid=%d)\n",
1789 		    ifp->if_xname, prefixlen, 128 - plen0));
1790 		return NULL;
1791 	}
1792 
1793 	/* make ifaddr */
1794 
1795 	bzero(&ifra, sizeof(ifra));
1796 	/*
1797 	 * in6_update_ifa() does not use ifra_name, but we accurately set it
1798 	 * for safety.
1799 	 */
1800 	strncpy(ifra.ifra_name, ifp->if_xname, sizeof(ifra.ifra_name));
1801 	ifra.ifra_addr.sin6_family = AF_INET6;
1802 	ifra.ifra_addr.sin6_len = sizeof(struct sockaddr_in6);
1803 	/* prefix */
1804 	bcopy(&pr->ndpr_prefix.sin6_addr, &ifra.ifra_addr.sin6_addr,
1805 	    sizeof(ifra.ifra_addr.sin6_addr));
1806 	ifra.ifra_addr.sin6_addr.s6_addr32[0] &= mask.s6_addr32[0];
1807 	ifra.ifra_addr.sin6_addr.s6_addr32[1] &= mask.s6_addr32[1];
1808 	ifra.ifra_addr.sin6_addr.s6_addr32[2] &= mask.s6_addr32[2];
1809 	ifra.ifra_addr.sin6_addr.s6_addr32[3] &= mask.s6_addr32[3];
1810 
1811 	/* interface ID */
1812 	if (privacy) {
1813 		ifra.ifra_flags |= IN6_IFF_PRIVACY;
1814 		bcopy(&pr->ndpr_prefix.sin6_addr, &rand_ifid,
1815 		    sizeof(rand_ifid));
1816 		in6_get_rand_ifid(ifp, &rand_ifid);
1817 		ifra.ifra_addr.sin6_addr.s6_addr32[0] |=
1818 		    (rand_ifid.s6_addr32[0] & ~mask.s6_addr32[0]);
1819 		ifra.ifra_addr.sin6_addr.s6_addr32[1] |=
1820 		    (rand_ifid.s6_addr32[1] & ~mask.s6_addr32[1]);
1821 		ifra.ifra_addr.sin6_addr.s6_addr32[2] |=
1822 		    (rand_ifid.s6_addr32[2] & ~mask.s6_addr32[2]);
1823 		ifra.ifra_addr.sin6_addr.s6_addr32[3] |=
1824 		    (rand_ifid.s6_addr32[3] & ~mask.s6_addr32[3]);
1825 	} else {
1826 		ifra.ifra_addr.sin6_addr.s6_addr32[0] |=
1827 		    (ia6->ia_addr.sin6_addr.s6_addr32[0] & ~mask.s6_addr32[0]);
1828 		ifra.ifra_addr.sin6_addr.s6_addr32[1] |=
1829 		    (ia6->ia_addr.sin6_addr.s6_addr32[1] & ~mask.s6_addr32[1]);
1830 		ifra.ifra_addr.sin6_addr.s6_addr32[2] |=
1831 		    (ia6->ia_addr.sin6_addr.s6_addr32[2] & ~mask.s6_addr32[2]);
1832 		ifra.ifra_addr.sin6_addr.s6_addr32[3] |=
1833 		    (ia6->ia_addr.sin6_addr.s6_addr32[3] & ~mask.s6_addr32[3]);
1834 	}
1835 
1836 	/* new prefix mask. */
1837 	ifra.ifra_prefixmask.sin6_len = sizeof(struct sockaddr_in6);
1838 	ifra.ifra_prefixmask.sin6_family = AF_INET6;
1839 	bcopy(&mask, &ifra.ifra_prefixmask.sin6_addr,
1840 	    sizeof(ifra.ifra_prefixmask.sin6_addr));
1841 
1842 	/*
1843 	 * lifetime.
1844 	 * XXX: in6_init_address_ltimes would override these values later.
1845 	 * We should reconsider this logic.
1846 	 */
1847 	ifra.ifra_lifetime.ia6t_vltime = pr->ndpr_vltime;
1848 	ifra.ifra_lifetime.ia6t_pltime = pr->ndpr_pltime;
1849 
1850 	if (privacy) {
1851 	    if (ifra.ifra_lifetime.ia6t_vltime > ND6_PRIV_VALID_LIFETIME)
1852 		ifra.ifra_lifetime.ia6t_vltime = ND6_PRIV_VALID_LIFETIME;
1853 	    if (ifra.ifra_lifetime.ia6t_pltime > ND6_PRIV_PREFERRED_LIFETIME)
1854 		ifra.ifra_lifetime.ia6t_pltime = ND6_PRIV_PREFERRED_LIFETIME
1855 			- (arc4random() % ND6_PRIV_MAX_DESYNC_FACTOR);
1856 	}
1857 
1858 	/* XXX: scope zone ID? */
1859 
1860 	ifra.ifra_flags |= IN6_IFF_AUTOCONF; /* obey autoconf */
1861 
1862 	/* allocate ifaddr structure, link into chain, etc. */
1863 	s = splsoftnet();
1864 	error = in6_update_ifa(ifp, &ifra, NULL);
1865 	splx(s);
1866 
1867 	if (error != 0) {
1868 		char addr[INET6_ADDRSTRLEN];
1869 
1870 		nd6log((LOG_ERR,
1871 		    "in6_ifadd: failed to make ifaddr %s on %s (errno=%d)\n",
1872 		    inet_ntop(AF_INET6,	&ifra.ifra_addr.sin6_addr,
1873 			addr, sizeof(addr)),
1874 		    ifp->if_xname, error));
1875 		return (NULL);	/* ifaddr must not have been allocated. */
1876 	}
1877 
1878 	/* this is always non-NULL */
1879 	return (in6ifa_ifpwithaddr(ifp, &ifra.ifra_addr.sin6_addr));
1880 }
1881 
1882 int
1883 in6_init_prefix_ltimes(struct nd_prefix *ndpr)
1884 {
1885 
1886 	/* check if preferred lifetime > valid lifetime.  RFC2462 5.5.3 (c) */
1887 	if (ndpr->ndpr_pltime > ndpr->ndpr_vltime) {
1888 		nd6log((LOG_INFO, "in6_init_prefix_ltimes: preferred lifetime"
1889 		    "(%d) is greater than valid lifetime(%d)\n",
1890 		    (u_int)ndpr->ndpr_pltime, (u_int)ndpr->ndpr_vltime));
1891 		return (EINVAL);
1892 	}
1893 	if (ndpr->ndpr_pltime == ND6_INFINITE_LIFETIME)
1894 		ndpr->ndpr_preferred = 0;
1895 	else
1896 		ndpr->ndpr_preferred = time_second + ndpr->ndpr_pltime;
1897 	if (ndpr->ndpr_vltime == ND6_INFINITE_LIFETIME)
1898 		ndpr->ndpr_expire = 0;
1899 	else
1900 		ndpr->ndpr_expire = time_second + ndpr->ndpr_vltime;
1901 
1902 	return 0;
1903 }
1904 
1905 void
1906 in6_init_address_ltimes(struct nd_prefix *new, struct in6_addrlifetime *lt6)
1907 {
1908 
1909 	/* Valid lifetime must not be updated unless explicitly specified. */
1910 	/* init ia6t_expire */
1911 	if (lt6->ia6t_vltime == ND6_INFINITE_LIFETIME)
1912 		lt6->ia6t_expire = 0;
1913 	else {
1914 		lt6->ia6t_expire = time_second;
1915 		lt6->ia6t_expire += lt6->ia6t_vltime;
1916 	}
1917 
1918 	/* init ia6t_preferred */
1919 	if (lt6->ia6t_pltime == ND6_INFINITE_LIFETIME)
1920 		lt6->ia6t_preferred = 0;
1921 	else {
1922 		lt6->ia6t_preferred = time_second;
1923 		lt6->ia6t_preferred += lt6->ia6t_pltime;
1924 	}
1925 }
1926 
1927 /*
1928  * Delete all the routing table entries that use the specified gateway.
1929  * XXX: this function causes search through all entries of routing table, so
1930  * it shouldn't be called when acting as a router.
1931  */
1932 void
1933 rt6_flush(struct in6_addr *gateway, struct ifnet *ifp)
1934 {
1935 	struct radix_node_head *rnh = rtable_get(ifp->if_rdomain, AF_INET6);
1936 	int s = splsoftnet();
1937 
1938 	/* We'll care only link-local addresses */
1939 	if (!IN6_IS_ADDR_LINKLOCAL(gateway)) {
1940 		splx(s);
1941 		return;
1942 	}
1943 	/* XXX: hack for KAME's link-local address kludge */
1944 	gateway->s6_addr16[1] = htons(ifp->if_index);
1945 
1946 	rnh->rnh_walktree(rnh, rt6_deleteroute, (void *)gateway);
1947 	splx(s);
1948 }
1949 
1950 int
1951 rt6_deleteroute(struct radix_node *rn, void *arg, u_int id)
1952 {
1953 	struct rt_addrinfo info;
1954 	struct rtentry *rt = (struct rtentry *)rn;
1955 	struct in6_addr *gate = (struct in6_addr *)arg;
1956 
1957 	if (rt->rt_gateway == NULL || rt->rt_gateway->sa_family != AF_INET6)
1958 		return (0);
1959 
1960 	if (!IN6_ARE_ADDR_EQUAL(gate, &satosin6(rt->rt_gateway)->sin6_addr))
1961 		return (0);
1962 
1963 	/*
1964 	 * Do not delete a static route.
1965 	 * XXX: this seems to be a bit ad-hoc. Should we consider the
1966 	 * 'cloned' bit instead?
1967 	 */
1968 	if ((rt->rt_flags & RTF_STATIC) != 0)
1969 		return (0);
1970 
1971 	/*
1972 	 * We delete only host route. This means, in particular, we don't
1973 	 * delete default route.
1974 	 */
1975 	if ((rt->rt_flags & RTF_HOST) == 0)
1976 		return (0);
1977 
1978 	bzero(&info, sizeof(info));
1979 	info.rti_flags =  rt->rt_flags;
1980 	info.rti_info[RTAX_DST] = rt_key(rt);
1981 	info.rti_info[RTAX_GATEWAY] = rt->rt_gateway;
1982 	info.rti_info[RTAX_NETMASK] = rt_mask(rt);
1983 	return (rtrequest1(RTM_DELETE, &info, RTP_ANY, NULL, id));
1984 }
1985