xref: /freebsd/sys/netinet6/nd6_nbr.c (revision ca9ac06c99bfd0150b85d4d83c396ce6237c0e05)
1 /*	$FreeBSD$	*/
2 /*	$KAME: nd6_nbr.c,v 1.86 2002/01/21 02:33:04 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 "opt_inet.h"
34 #include "opt_inet6.h"
35 #include "opt_ipsec.h"
36 #include "opt_carp.h"
37 
38 #include <sys/param.h>
39 #include <sys/systm.h>
40 #include <sys/malloc.h>
41 #include <sys/mbuf.h>
42 #include <sys/socket.h>
43 #include <sys/sockio.h>
44 #include <sys/time.h>
45 #include <sys/kernel.h>
46 #include <sys/errno.h>
47 #include <sys/syslog.h>
48 #include <sys/queue.h>
49 #include <sys/callout.h>
50 
51 #include <net/if.h>
52 #include <net/if_types.h>
53 #include <net/if_dl.h>
54 #include <net/route.h>
55 
56 #include <netinet/in.h>
57 #include <netinet/in_var.h>
58 #include <netinet6/in6_var.h>
59 #include <netinet/ip6.h>
60 #include <netinet6/ip6_var.h>
61 #include <netinet6/nd6.h>
62 #include <netinet/icmp6.h>
63 
64 #ifdef DEV_CARP
65 #include <netinet/ip_carp.h>
66 #endif
67 
68 #include <net/net_osdep.h>
69 
70 #define SDL(s) ((struct sockaddr_dl *)s)
71 
72 struct dadq;
73 static struct dadq *nd6_dad_find __P((struct ifaddr *));
74 static void nd6_dad_starttimer __P((struct dadq *, int));
75 static void nd6_dad_stoptimer __P((struct dadq *));
76 static void nd6_dad_timer __P((struct ifaddr *));
77 static void nd6_dad_ns_output __P((struct dadq *, struct ifaddr *));
78 static void nd6_dad_ns_input __P((struct ifaddr *));
79 static void nd6_dad_na_input __P((struct ifaddr *));
80 
81 static int dad_ignore_ns = 0;	/* ignore NS in DAD - specwise incorrect*/
82 static int dad_maxtry = 15;	/* max # of *tries* to transmit DAD packet */
83 
84 /*
85  * Input a Neighbor Solicitation Message.
86  *
87  * Based on RFC 2461
88  * Based on RFC 2462 (duplicated address detection)
89  */
90 void
91 nd6_ns_input(m, off, icmp6len)
92 	struct mbuf *m;
93 	int off, icmp6len;
94 {
95 	struct ifnet *ifp = m->m_pkthdr.rcvif;
96 	struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
97 	struct nd_neighbor_solicit *nd_ns;
98 	struct in6_addr saddr6 = ip6->ip6_src;
99 	struct in6_addr daddr6 = ip6->ip6_dst;
100 	struct in6_addr taddr6;
101 	struct in6_addr myaddr6;
102 	char *lladdr = NULL;
103 	struct ifaddr *ifa = NULL;
104 	int lladdrlen = 0;
105 	int anycast = 0, proxy = 0, tentative = 0;
106 	int tlladdr;
107 	union nd_opts ndopts;
108 	struct sockaddr_dl *proxydl = NULL;
109 
110 #ifndef PULLDOWN_TEST
111 	IP6_EXTHDR_CHECK(m, off, icmp6len,);
112 	nd_ns = (struct nd_neighbor_solicit *)((caddr_t)ip6 + off);
113 #else
114 	IP6_EXTHDR_GET(nd_ns, struct nd_neighbor_solicit *, m, off, icmp6len);
115 	if (nd_ns == NULL) {
116 		icmp6stat.icp6s_tooshort++;
117 		return;
118 	}
119 #endif
120 	ip6 = mtod(m, struct ip6_hdr *); /* adjust pointer for safety */
121 	taddr6 = nd_ns->nd_ns_target;
122 
123 	if (ip6->ip6_hlim != 255) {
124 		nd6log((LOG_ERR,
125 		    "nd6_ns_input: invalid hlim (%d) from %s to %s on %s\n",
126 		    ip6->ip6_hlim, ip6_sprintf(&ip6->ip6_src),
127 		    ip6_sprintf(&ip6->ip6_dst), if_name(ifp)));
128 		goto bad;
129 	}
130 
131 	if (IN6_IS_ADDR_UNSPECIFIED(&saddr6)) {
132 		/* dst has to be solicited node multicast address. */
133 		if (daddr6.s6_addr16[0] == IPV6_ADDR_INT16_MLL &&
134 		    /* don't check ifindex portion */
135 		    daddr6.s6_addr32[1] == 0 &&
136 		    daddr6.s6_addr32[2] == IPV6_ADDR_INT32_ONE &&
137 		    daddr6.s6_addr8[12] == 0xff) {
138 			; /* good */
139 		} else {
140 			nd6log((LOG_INFO, "nd6_ns_input: bad DAD packet "
141 			    "(wrong ip6 dst)\n"));
142 			goto bad;
143 		}
144 	}
145 
146 	if (IN6_IS_ADDR_MULTICAST(&taddr6)) {
147 		nd6log((LOG_INFO, "nd6_ns_input: bad NS target (multicast)\n"));
148 		goto bad;
149 	}
150 
151 	if (IN6_IS_SCOPE_LINKLOCAL(&taddr6))
152 		taddr6.s6_addr16[1] = htons(ifp->if_index);
153 
154 	icmp6len -= sizeof(*nd_ns);
155 	nd6_option_init(nd_ns + 1, icmp6len, &ndopts);
156 	if (nd6_options(&ndopts) < 0) {
157 		nd6log((LOG_INFO,
158 		    "nd6_ns_input: invalid ND option, ignored\n"));
159 		/* nd6_options have incremented stats */
160 		goto freeit;
161 	}
162 
163 	if (ndopts.nd_opts_src_lladdr) {
164 		lladdr = (char *)(ndopts.nd_opts_src_lladdr + 1);
165 		lladdrlen = ndopts.nd_opts_src_lladdr->nd_opt_len << 3;
166 	}
167 
168 	if (IN6_IS_ADDR_UNSPECIFIED(&ip6->ip6_src) && lladdr) {
169 		nd6log((LOG_INFO, "nd6_ns_input: bad DAD packet "
170 		    "(link-layer address option)\n"));
171 		goto bad;
172 	}
173 
174 	/*
175 	 * Attaching target link-layer address to the NA?
176 	 * (RFC 2461 7.2.4)
177 	 *
178 	 * NS IP dst is unicast/anycast			MUST NOT add
179 	 * NS IP dst is solicited-node multicast	MUST add
180 	 *
181 	 * In implementation, we add target link-layer address by default.
182 	 * We do not add one in MUST NOT cases.
183 	 */
184 #if 0 /* too much! */
185 	ifa = (struct ifaddr *)in6ifa_ifpwithaddr(ifp, &daddr6);
186 	if (ifa && (((struct in6_ifaddr *)ifa)->ia6_flags & IN6_IFF_ANYCAST))
187 		tlladdr = 0;
188 	else
189 #endif
190 	if (!IN6_IS_ADDR_MULTICAST(&daddr6))
191 		tlladdr = 0;
192 	else
193 		tlladdr = 1;
194 
195 	/*
196 	 * Target address (taddr6) must be either:
197 	 * (1) Valid unicast/anycast address for my receiving interface,
198 	 * (2) Unicast address for which I'm offering proxy service, or
199 	 * (3) "tentative" address on which DAD is being performed.
200 	 */
201 	/* (1) and (3) check. */
202 #ifdef DEV_CARP
203 	if (ifp->if_carp)
204 		ifa = carp_iamatch6(ifp->if_carp, &taddr6);
205 	if (!ifa)
206 		ifa = (struct ifaddr *)in6ifa_ifpwithaddr(ifp, &taddr6);
207 #else
208 	ifa = (struct ifaddr *)in6ifa_ifpwithaddr(ifp, &taddr6);
209 #endif
210 
211 	/* (2) check. */
212 	if (!ifa) {
213 		struct rtentry *rt;
214 		struct sockaddr_in6 tsin6;
215 		int need_proxy;
216 
217 		bzero(&tsin6, sizeof tsin6);
218 		tsin6.sin6_len = sizeof(struct sockaddr_in6);
219 		tsin6.sin6_family = AF_INET6;
220 		tsin6.sin6_addr = taddr6;
221 
222 		rt = rtalloc1((struct sockaddr *)&tsin6, 0, 0);
223 		need_proxy = (rt && (rt->rt_flags & RTF_ANNOUNCE) != 0 &&
224 		    rt->rt_gateway->sa_family == AF_LINK);
225 		if (rt)
226 			rtfree(rt);
227 		if (need_proxy) {
228 			/*
229 			 * proxy NDP for single entry
230 			 */
231 			ifa = (struct ifaddr *)in6ifa_ifpforlinklocal(ifp,
232 				IN6_IFF_NOTREADY|IN6_IFF_ANYCAST);
233 			if (ifa) {
234 				proxy = 1;
235 				proxydl = SDL(rt->rt_gateway);
236 			}
237 		}
238 	}
239 	if (!ifa) {
240 		/*
241 		 * We've got an NS packet, and we don't have that adddress
242 		 * assigned for us.  We MUST silently ignore it.
243 		 * See RFC2461 7.2.3.
244 		 */
245 		goto freeit;
246 	}
247 	myaddr6 = *IFA_IN6(ifa);
248 	anycast = ((struct in6_ifaddr *)ifa)->ia6_flags & IN6_IFF_ANYCAST;
249 	tentative = ((struct in6_ifaddr *)ifa)->ia6_flags & IN6_IFF_TENTATIVE;
250 	if (((struct in6_ifaddr *)ifa)->ia6_flags & IN6_IFF_DUPLICATED)
251 		goto freeit;
252 
253 	if (lladdr && ((ifp->if_addrlen + 2 + 7) & ~7) != lladdrlen) {
254 		nd6log((LOG_INFO, "nd6_ns_input: lladdrlen mismatch for %s "
255 		    "(if %d, NS packet %d)\n",
256 		    ip6_sprintf(&taddr6),
257 		    ifp->if_addrlen, lladdrlen - 2));
258 		goto bad;
259 	}
260 
261 	if (IN6_ARE_ADDR_EQUAL(&myaddr6, &saddr6)) {
262 		nd6log((LOG_INFO, "nd6_ns_input: duplicate IP6 address %s\n",
263 		    ip6_sprintf(&saddr6)));
264 		goto freeit;
265 	}
266 
267 	/*
268 	 * We have neighbor solicitation packet, with target address equals to
269 	 * one of my tentative address.
270 	 *
271 	 * src addr	how to process?
272 	 * ---		---
273 	 * multicast	of course, invalid (rejected in ip6_input)
274 	 * unicast	somebody is doing address resolution -> ignore
275 	 * unspec	dup address detection
276 	 *
277 	 * The processing is defined in RFC 2462.
278 	 */
279 	if (tentative) {
280 		/*
281 		 * If source address is unspecified address, it is for
282 		 * duplicated address detection.
283 		 *
284 		 * If not, the packet is for addess resolution;
285 		 * silently ignore it.
286 		 */
287 		if (IN6_IS_ADDR_UNSPECIFIED(&saddr6))
288 			nd6_dad_ns_input(ifa);
289 
290 		goto freeit;
291 	}
292 
293 	/*
294 	 * If the source address is unspecified address, entries must not
295 	 * be created or updated.
296 	 * It looks that sender is performing DAD.  Output NA toward
297 	 * all-node multicast address, to tell the sender that I'm using
298 	 * the address.
299 	 * S bit ("solicited") must be zero.
300 	 */
301 	if (IN6_IS_ADDR_UNSPECIFIED(&saddr6)) {
302 		saddr6 = in6addr_linklocal_allnodes;
303 		saddr6.s6_addr16[1] = htons(ifp->if_index);
304 		nd6_na_output(ifp, &saddr6, &taddr6,
305 		    ((anycast || proxy || !tlladdr) ? 0 : ND_NA_FLAG_OVERRIDE) |
306 		    (ip6_forwarding ? ND_NA_FLAG_ROUTER : 0),
307 		    tlladdr, (struct sockaddr *)proxydl);
308 		goto freeit;
309 	}
310 
311 	nd6_cache_lladdr(ifp, &saddr6, lladdr, lladdrlen,
312 	    ND_NEIGHBOR_SOLICIT, 0);
313 
314 	nd6_na_output(ifp, &saddr6, &taddr6,
315 	    ((anycast || proxy || !tlladdr) ? 0 : ND_NA_FLAG_OVERRIDE) |
316 	    (ip6_forwarding ? ND_NA_FLAG_ROUTER : 0) | ND_NA_FLAG_SOLICITED,
317 	    tlladdr, (struct sockaddr *)proxydl);
318  freeit:
319 	m_freem(m);
320 	return;
321 
322  bad:
323 	nd6log((LOG_ERR, "nd6_ns_input: src=%s\n", ip6_sprintf(&saddr6)));
324 	nd6log((LOG_ERR, "nd6_ns_input: dst=%s\n", ip6_sprintf(&daddr6)));
325 	nd6log((LOG_ERR, "nd6_ns_input: tgt=%s\n", ip6_sprintf(&taddr6)));
326 	icmp6stat.icp6s_badns++;
327 	m_freem(m);
328 }
329 
330 /*
331  * Output a Neighbor Solicitation Message. Caller specifies:
332  *	- ICMP6 header source IP6 address
333  *	- ND6 header target IP6 address
334  *	- ND6 header source datalink address
335  *
336  * Based on RFC 2461
337  * Based on RFC 2462 (duplicated address detection)
338  */
339 void
340 nd6_ns_output(ifp, daddr6, taddr6, ln, dad)
341 	struct ifnet *ifp;
342 	const struct in6_addr *daddr6, *taddr6;
343 	struct llinfo_nd6 *ln;	/* for source address determination */
344 	int dad;	/* duplicated address detection */
345 {
346 	struct mbuf *m;
347 	struct ip6_hdr *ip6;
348 	struct nd_neighbor_solicit *nd_ns;
349 	struct in6_ifaddr *ia = NULL;
350 	struct ip6_moptions im6o;
351 	int icmp6len;
352 	int maxlen;
353 	caddr_t mac;
354 	struct ifnet *outif = NULL;
355 
356 	if (IN6_IS_ADDR_MULTICAST(taddr6))
357 		return;
358 
359 	/* estimate the size of message */
360 	maxlen = sizeof(*ip6) + sizeof(*nd_ns);
361 	maxlen += (sizeof(struct nd_opt_hdr) + ifp->if_addrlen + 7) & ~7;
362 	if (max_linkhdr + maxlen >= MCLBYTES) {
363 #ifdef DIAGNOSTIC
364 		printf("nd6_ns_output: max_linkhdr + maxlen >= MCLBYTES "
365 		    "(%d + %d > %d)\n", max_linkhdr, maxlen, MCLBYTES);
366 #endif
367 		return;
368 	}
369 
370 	MGETHDR(m, M_DONTWAIT, MT_DATA);
371 	if (m && max_linkhdr + maxlen >= MHLEN) {
372 		MCLGET(m, M_DONTWAIT);
373 		if ((m->m_flags & M_EXT) == 0) {
374 			m_free(m);
375 			m = NULL;
376 		}
377 	}
378 	if (m == NULL)
379 		return;
380 	m->m_pkthdr.rcvif = NULL;
381 
382 	if (daddr6 == NULL || IN6_IS_ADDR_MULTICAST(daddr6)) {
383 		m->m_flags |= M_MCAST;
384 		im6o.im6o_multicast_ifp = ifp;
385 		im6o.im6o_multicast_hlim = 255;
386 		im6o.im6o_multicast_loop = 0;
387 	}
388 
389 	icmp6len = sizeof(*nd_ns);
390 	m->m_pkthdr.len = m->m_len = sizeof(*ip6) + icmp6len;
391 	m->m_data += max_linkhdr;	/* or MH_ALIGN() equivalent? */
392 
393 	/* fill neighbor solicitation packet */
394 	ip6 = mtod(m, struct ip6_hdr *);
395 	ip6->ip6_flow = 0;
396 	ip6->ip6_vfc &= ~IPV6_VERSION_MASK;
397 	ip6->ip6_vfc |= IPV6_VERSION;
398 	/* ip6->ip6_plen will be set later */
399 	ip6->ip6_nxt = IPPROTO_ICMPV6;
400 	ip6->ip6_hlim = 255;
401 	if (daddr6)
402 		ip6->ip6_dst = *daddr6;
403 	else {
404 		ip6->ip6_dst.s6_addr16[0] = IPV6_ADDR_INT16_MLL;
405 		ip6->ip6_dst.s6_addr16[1] = htons(ifp->if_index);
406 		ip6->ip6_dst.s6_addr32[1] = 0;
407 		ip6->ip6_dst.s6_addr32[2] = IPV6_ADDR_INT32_ONE;
408 		ip6->ip6_dst.s6_addr32[3] = taddr6->s6_addr32[3];
409 		ip6->ip6_dst.s6_addr8[12] = 0xff;
410 	}
411 	if (!dad) {
412 		/*
413 		 * RFC2461 7.2.2:
414 		 * "If the source address of the packet prompting the
415 		 * solicitation is the same as one of the addresses assigned
416 		 * to the outgoing interface, that address SHOULD be placed
417 		 * in the IP Source Address of the outgoing solicitation.
418 		 * Otherwise, any one of the addresses assigned to the
419 		 * interface should be used."
420 		 *
421 		 * We use the source address for the prompting packet
422 		 * (saddr6), if:
423 		 * - saddr6 is given from the caller (by giving "ln"), and
424 		 * - saddr6 belongs to the outgoing interface.
425 		 * Otherwise, we perform a scope-wise match.
426 		 */
427 		struct ip6_hdr *hip6;		/* hold ip6 */
428 		struct in6_addr *saddr6;
429 
430 		if (ln && ln->ln_hold) {
431 			hip6 = mtod(ln->ln_hold, struct ip6_hdr *);
432 			/* XXX pullup? */
433 			if (sizeof(*hip6) < ln->ln_hold->m_len)
434 				saddr6 = &hip6->ip6_src;
435 			else
436 				saddr6 = NULL;
437 		} else
438 			saddr6 = NULL;
439 		if (saddr6 && in6ifa_ifpwithaddr(ifp, saddr6))
440 			bcopy(saddr6, &ip6->ip6_src, sizeof(*saddr6));
441 		else {
442 			ia = in6_ifawithifp(ifp, &ip6->ip6_dst);
443 			if (ia == NULL) {
444 				m_freem(m);
445 				return;
446 			}
447 			ip6->ip6_src = ia->ia_addr.sin6_addr;
448 		}
449 	} else {
450 		/*
451 		 * Source address for DAD packet must always be IPv6
452 		 * unspecified address. (0::0)
453 		 */
454 		bzero(&ip6->ip6_src, sizeof(ip6->ip6_src));
455 	}
456 	nd_ns = (struct nd_neighbor_solicit *)(ip6 + 1);
457 	nd_ns->nd_ns_type = ND_NEIGHBOR_SOLICIT;
458 	nd_ns->nd_ns_code = 0;
459 	nd_ns->nd_ns_reserved = 0;
460 	nd_ns->nd_ns_target = *taddr6;
461 	in6_clearscope(&nd_ns->nd_ns_target); /* XXX */
462 
463 	/*
464 	 * Add source link-layer address option.
465 	 *
466 	 *				spec		implementation
467 	 *				---		---
468 	 * DAD packet			MUST NOT	do not add the option
469 	 * there's no link layer address:
470 	 *				impossible	do not add the option
471 	 * there's link layer address:
472 	 *	Multicast NS		MUST add one	add the option
473 	 *	Unicast NS		SHOULD add one	add the option
474 	 */
475 	if (!dad && (mac = nd6_ifptomac(ifp))) {
476 		int optlen = sizeof(struct nd_opt_hdr) + ifp->if_addrlen;
477 		struct nd_opt_hdr *nd_opt = (struct nd_opt_hdr *)(nd_ns + 1);
478 		/* 8 byte alignments... */
479 		optlen = (optlen + 7) & ~7;
480 
481 		m->m_pkthdr.len += optlen;
482 		m->m_len += optlen;
483 		icmp6len += optlen;
484 		bzero((caddr_t)nd_opt, optlen);
485 		nd_opt->nd_opt_type = ND_OPT_SOURCE_LINKADDR;
486 		nd_opt->nd_opt_len = optlen >> 3;
487 		bcopy(mac, (caddr_t)(nd_opt + 1), ifp->if_addrlen);
488 	}
489 
490 	ip6->ip6_plen = htons((u_short)icmp6len);
491 	nd_ns->nd_ns_cksum = 0;
492 	nd_ns->nd_ns_cksum =
493 	    in6_cksum(m, IPPROTO_ICMPV6, sizeof(*ip6), icmp6len);
494 
495 	ip6_output(m, NULL, NULL, dad ? IPV6_DADOUTPUT : 0, &im6o, &outif, NULL);
496 	if (outif) {
497 		icmp6_ifstat_inc(outif, ifs6_out_msg);
498 		icmp6_ifstat_inc(outif, ifs6_out_neighborsolicit);
499 	}
500 	icmp6stat.icp6s_outhist[ND_NEIGHBOR_SOLICIT]++;
501 }
502 
503 /*
504  * Neighbor advertisement input handling.
505  *
506  * Based on RFC 2461
507  * Based on RFC 2462 (duplicated address detection)
508  *
509  * the following items are not implemented yet:
510  * - proxy advertisement delay rule (RFC2461 7.2.8, last paragraph, SHOULD)
511  * - anycast advertisement delay rule (RFC2461 7.2.7, SHOULD)
512  */
513 void
514 nd6_na_input(m, off, icmp6len)
515 	struct mbuf *m;
516 	int off, icmp6len;
517 {
518 	struct ifnet *ifp = m->m_pkthdr.rcvif;
519 	struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
520 	struct nd_neighbor_advert *nd_na;
521 	struct in6_addr daddr6 = ip6->ip6_dst;
522 	struct in6_addr taddr6;
523 	int flags;
524 	int is_router;
525 	int is_solicited;
526 	int is_override;
527 	char *lladdr = NULL;
528 	int lladdrlen = 0;
529 	struct ifaddr *ifa;
530 	struct llinfo_nd6 *ln;
531 	struct rtentry *rt;
532 	struct sockaddr_dl *sdl;
533 	union nd_opts ndopts;
534 
535 	if (ip6->ip6_hlim != 255) {
536 		nd6log((LOG_ERR,
537 		    "nd6_na_input: invalid hlim (%d) from %s to %s on %s\n",
538 		    ip6->ip6_hlim, ip6_sprintf(&ip6->ip6_src),
539 		    ip6_sprintf(&ip6->ip6_dst), if_name(ifp)));
540 		goto bad;
541 	}
542 
543 #ifndef PULLDOWN_TEST
544 	IP6_EXTHDR_CHECK(m, off, icmp6len,);
545 	nd_na = (struct nd_neighbor_advert *)((caddr_t)ip6 + off);
546 #else
547 	IP6_EXTHDR_GET(nd_na, struct nd_neighbor_advert *, m, off, icmp6len);
548 	if (nd_na == NULL) {
549 		icmp6stat.icp6s_tooshort++;
550 		return;
551 	}
552 #endif
553 	taddr6 = nd_na->nd_na_target;
554 	flags = nd_na->nd_na_flags_reserved;
555 	is_router = ((flags & ND_NA_FLAG_ROUTER) != 0);
556 	is_solicited = ((flags & ND_NA_FLAG_SOLICITED) != 0);
557 	is_override = ((flags & ND_NA_FLAG_OVERRIDE) != 0);
558 
559 	if (IN6_IS_SCOPE_LINKLOCAL(&taddr6))
560 		taddr6.s6_addr16[1] = htons(ifp->if_index);
561 
562 	if (IN6_IS_ADDR_MULTICAST(&taddr6)) {
563 		nd6log((LOG_ERR,
564 		    "nd6_na_input: invalid target address %s\n",
565 		    ip6_sprintf(&taddr6)));
566 		goto bad;
567 	}
568 	if (IN6_IS_ADDR_MULTICAST(&daddr6))
569 		if (is_solicited) {
570 			nd6log((LOG_ERR,
571 			    "nd6_na_input: a solicited adv is multicasted\n"));
572 			goto bad;
573 		}
574 
575 	icmp6len -= sizeof(*nd_na);
576 	nd6_option_init(nd_na + 1, icmp6len, &ndopts);
577 	if (nd6_options(&ndopts) < 0) {
578 		nd6log((LOG_INFO,
579 		    "nd6_na_input: invalid ND option, ignored\n"));
580 		/* nd6_options have incremented stats */
581 		goto freeit;
582 	}
583 
584 	if (ndopts.nd_opts_tgt_lladdr) {
585 		lladdr = (char *)(ndopts.nd_opts_tgt_lladdr + 1);
586 		lladdrlen = ndopts.nd_opts_tgt_lladdr->nd_opt_len << 3;
587 	}
588 
589 	ifa = (struct ifaddr *)in6ifa_ifpwithaddr(ifp, &taddr6);
590 
591 	/*
592 	 * Target address matches one of my interface address.
593 	 *
594 	 * If my address is tentative, this means that there's somebody
595 	 * already using the same address as mine.  This indicates DAD failure.
596 	 * This is defined in RFC 2462.
597 	 *
598 	 * Otherwise, process as defined in RFC 2461.
599 	 */
600 	if (ifa
601 	 && (((struct in6_ifaddr *)ifa)->ia6_flags & IN6_IFF_TENTATIVE)) {
602 		nd6_dad_na_input(ifa);
603 		goto freeit;
604 	}
605 
606 	/* Just for safety, maybe unnecessary. */
607 	if (ifa) {
608 		log(LOG_ERR,
609 		    "nd6_na_input: duplicate IP6 address %s\n",
610 		    ip6_sprintf(&taddr6));
611 		goto freeit;
612 	}
613 
614 	if (lladdr && ((ifp->if_addrlen + 2 + 7) & ~7) != lladdrlen) {
615 		nd6log((LOG_INFO, "nd6_na_input: lladdrlen mismatch for %s "
616 		    "(if %d, NA packet %d)\n", ip6_sprintf(&taddr6),
617 		    ifp->if_addrlen, lladdrlen - 2));
618 		goto bad;
619 	}
620 
621 	/*
622 	 * If no neighbor cache entry is found, NA SHOULD silently be
623 	 * discarded.
624 	 */
625 	rt = nd6_lookup(&taddr6, 0, ifp);
626 	if ((rt == NULL) ||
627 	   ((ln = (struct llinfo_nd6 *)rt->rt_llinfo) == NULL) ||
628 	   ((sdl = SDL(rt->rt_gateway)) == NULL))
629 		goto freeit;
630 
631 	if (ln->ln_state == ND6_LLINFO_INCOMPLETE) {
632 		/*
633 		 * If the link-layer has address, and no lladdr option came,
634 		 * discard the packet.
635 		 */
636 		if (ifp->if_addrlen && !lladdr)
637 			goto freeit;
638 
639 		/*
640 		 * Record link-layer address, and update the state.
641 		 */
642 		sdl->sdl_alen = ifp->if_addrlen;
643 		bcopy(lladdr, LLADDR(sdl), ifp->if_addrlen);
644 		if (is_solicited) {
645 			ln->ln_state = ND6_LLINFO_REACHABLE;
646 			ln->ln_byhint = 0;
647 			if (ln->ln_expire) {
648 				ln->ln_expire = time_second +
649 				    ND_IFINFO(rt->rt_ifp)->reachable;
650 			}
651 		} else {
652 			ln->ln_state = ND6_LLINFO_STALE;
653 			ln->ln_expire = time_second + nd6_gctimer;
654 		}
655 		if ((ln->ln_router = is_router) != 0) {
656 			/*
657 			 * This means a router's state has changed from
658 			 * non-reachable to probably reachable, and might
659 			 * affect the status of associated prefixes..
660 			 */
661 			pfxlist_onlink_check();
662 		}
663 	} else {
664 		int llchange;
665 
666 		/*
667 		 * Check if the link-layer address has changed or not.
668 		 */
669 		if (!lladdr)
670 			llchange = 0;
671 		else {
672 			if (sdl->sdl_alen) {
673 				if (bcmp(lladdr, LLADDR(sdl), ifp->if_addrlen))
674 					llchange = 1;
675 				else
676 					llchange = 0;
677 			} else
678 				llchange = 1;
679 		}
680 
681 		/*
682 		 * This is VERY complex.  Look at it with care.
683 		 *
684 		 * override solicit lladdr llchange	action
685 		 *					(L: record lladdr)
686 		 *
687 		 *	0	0	n	--	(2c)
688 		 *	0	0	y	n	(2b) L
689 		 *	0	0	y	y	(1)    REACHABLE->STALE
690 		 *	0	1	n	--	(2c)   *->REACHABLE
691 		 *	0	1	y	n	(2b) L *->REACHABLE
692 		 *	0	1	y	y	(1)    REACHABLE->STALE
693 		 *	1	0	n	--	(2a)
694 		 *	1	0	y	n	(2a) L
695 		 *	1	0	y	y	(2a) L *->STALE
696 		 *	1	1	n	--	(2a)   *->REACHABLE
697 		 *	1	1	y	n	(2a) L *->REACHABLE
698 		 *	1	1	y	y	(2a) L *->REACHABLE
699 		 */
700 		if (!is_override && (lladdr && llchange)) {	   /* (1) */
701 			/*
702 			 * If state is REACHABLE, make it STALE.
703 			 * no other updates should be done.
704 			 */
705 			if (ln->ln_state == ND6_LLINFO_REACHABLE) {
706 				ln->ln_state = ND6_LLINFO_STALE;
707 				ln->ln_expire = time_second + nd6_gctimer;
708 			}
709 			goto freeit;
710 		} else if (is_override				   /* (2a) */
711 			|| (!is_override && (lladdr && !llchange)) /* (2b) */
712 			|| !lladdr) {				   /* (2c) */
713 			/*
714 			 * Update link-local address, if any.
715 			 */
716 			if (lladdr) {
717 				sdl->sdl_alen = ifp->if_addrlen;
718 				bcopy(lladdr, LLADDR(sdl), ifp->if_addrlen);
719 			}
720 
721 			/*
722 			 * If solicited, make the state REACHABLE.
723 			 * If not solicited and the link-layer address was
724 			 * changed, make it STALE.
725 			 */
726 			if (is_solicited) {
727 				ln->ln_state = ND6_LLINFO_REACHABLE;
728 				ln->ln_byhint = 0;
729 				if (ln->ln_expire) {
730 					ln->ln_expire = time_second +
731 					    ND_IFINFO(ifp)->reachable;
732 				}
733 			} else {
734 				if (lladdr && llchange) {
735 					ln->ln_state = ND6_LLINFO_STALE;
736 					ln->ln_expire = time_second + nd6_gctimer;
737 				}
738 			}
739 		}
740 
741 		if (ln->ln_router && !is_router) {
742 			/*
743 			 * The peer dropped the router flag.
744 			 * Remove the sender from the Default Router List and
745 			 * update the Destination Cache entries.
746 			 */
747 			struct nd_defrouter *dr;
748 			struct in6_addr *in6;
749 			int s;
750 
751 			in6 = &((struct sockaddr_in6 *)rt_key(rt))->sin6_addr;
752 
753 			/*
754 			 * Lock to protect the default router list.
755 			 * XXX: this might be unnecessary, since this function
756 			 * is only called under the network software interrupt
757 			 * context.  However, we keep it just for safety.
758 			 */
759 			s = splnet();
760 			dr = defrouter_lookup(in6, ifp);
761 			if (dr)
762 				defrtrlist_del(dr);
763 			else if (!ip6_forwarding && ip6_accept_rtadv) {
764 				/*
765 				 * Even if the neighbor is not in the default
766 				 * router list, the neighbor may be used
767 				 * as a next hop for some destinations
768 				 * (e.g. redirect case). So we must
769 				 * call rt6_flush explicitly.
770 				 */
771 				rt6_flush(&ip6->ip6_src, ifp);
772 			}
773 			splx(s);
774 		}
775 		ln->ln_router = is_router;
776 	}
777 	rt->rt_flags &= ~RTF_REJECT;
778 	ln->ln_asked = 0;
779 	if (ln->ln_hold) {
780 		/*
781 		 * we assume ifp is not a loopback here, so just set the 2nd
782 		 * argument as the 1st one.
783 		 */
784 		nd6_output(ifp, ifp, ln->ln_hold,
785 			   (struct sockaddr_in6 *)rt_key(rt), rt);
786 		ln->ln_hold = NULL;
787 	}
788 
789  freeit:
790 	m_freem(m);
791 	return;
792 
793  bad:
794 	icmp6stat.icp6s_badna++;
795 	m_freem(m);
796 }
797 
798 /*
799  * Neighbor advertisement output handling.
800  *
801  * Based on RFC 2461
802  *
803  * the following items are not implemented yet:
804  * - proxy advertisement delay rule (RFC2461 7.2.8, last paragraph, SHOULD)
805  * - anycast advertisement delay rule (RFC2461 7.2.7, SHOULD)
806  */
807 void
808 nd6_na_output(ifp, daddr6, taddr6, flags, tlladdr, sdl0)
809 	struct ifnet *ifp;
810 	const struct in6_addr *daddr6, *taddr6;
811 	u_long flags;
812 	int tlladdr;		/* 1 if include target link-layer address */
813 	struct sockaddr *sdl0;	/* sockaddr_dl (= proxy NA) or NULL */
814 {
815 	struct mbuf *m;
816 	struct ip6_hdr *ip6;
817 	struct nd_neighbor_advert *nd_na;
818 	struct in6_ifaddr *ia = NULL;
819 	struct ip6_moptions im6o;
820 	int icmp6len;
821 	int maxlen;
822 	caddr_t mac = NULL;
823 	struct ifnet *outif = NULL;
824 
825 	/* estimate the size of message */
826 	maxlen = sizeof(*ip6) + sizeof(*nd_na);
827 	maxlen += (sizeof(struct nd_opt_hdr) + ifp->if_addrlen + 7) & ~7;
828 	if (max_linkhdr + maxlen >= MCLBYTES) {
829 #ifdef DIAGNOSTIC
830 		printf("nd6_na_output: max_linkhdr + maxlen >= MCLBYTES "
831 		    "(%d + %d > %d)\n", max_linkhdr, maxlen, MCLBYTES);
832 #endif
833 		return;
834 	}
835 
836 	MGETHDR(m, M_DONTWAIT, MT_DATA);
837 	if (m && max_linkhdr + maxlen >= MHLEN) {
838 		MCLGET(m, M_DONTWAIT);
839 		if ((m->m_flags & M_EXT) == 0) {
840 			m_free(m);
841 			m = NULL;
842 		}
843 	}
844 	if (m == NULL)
845 		return;
846 	m->m_pkthdr.rcvif = NULL;
847 
848 	if (IN6_IS_ADDR_MULTICAST(daddr6)) {
849 		m->m_flags |= M_MCAST;
850 		im6o.im6o_multicast_ifp = ifp;
851 		im6o.im6o_multicast_hlim = 255;
852 		im6o.im6o_multicast_loop = 0;
853 	}
854 
855 	icmp6len = sizeof(*nd_na);
856 	m->m_pkthdr.len = m->m_len = sizeof(struct ip6_hdr) + icmp6len;
857 	m->m_data += max_linkhdr;	/* or MH_ALIGN() equivalent? */
858 
859 	/* fill neighbor advertisement packet */
860 	ip6 = mtod(m, struct ip6_hdr *);
861 	ip6->ip6_flow = 0;
862 	ip6->ip6_vfc &= ~IPV6_VERSION_MASK;
863 	ip6->ip6_vfc |= IPV6_VERSION;
864 	ip6->ip6_nxt = IPPROTO_ICMPV6;
865 	ip6->ip6_hlim = 255;
866 	if (IN6_IS_ADDR_UNSPECIFIED(daddr6)) {
867 		/* reply to DAD */
868 		ip6->ip6_dst.s6_addr16[0] = IPV6_ADDR_INT16_MLL;
869 		ip6->ip6_dst.s6_addr16[1] = htons(ifp->if_index);
870 		ip6->ip6_dst.s6_addr32[1] = 0;
871 		ip6->ip6_dst.s6_addr32[2] = 0;
872 		ip6->ip6_dst.s6_addr32[3] = IPV6_ADDR_INT32_ONE;
873 		flags &= ~ND_NA_FLAG_SOLICITED;
874 	} else
875 		ip6->ip6_dst = *daddr6;
876 
877 	/*
878 	 * Select a source whose scope is the same as that of the dest.
879 	 */
880 	ia = in6_ifawithifp(ifp, &ip6->ip6_dst);
881 	if (ia == NULL) {
882 		m_freem(m);
883 		return;
884 	}
885 	ip6->ip6_src = ia->ia_addr.sin6_addr;
886 	nd_na = (struct nd_neighbor_advert *)(ip6 + 1);
887 	nd_na->nd_na_type = ND_NEIGHBOR_ADVERT;
888 	nd_na->nd_na_code = 0;
889 	nd_na->nd_na_target = *taddr6;
890 	in6_clearscope(&nd_na->nd_na_target); /* XXX */
891 
892 	/*
893 	 * "tlladdr" indicates NS's condition for adding tlladdr or not.
894 	 * see nd6_ns_input() for details.
895 	 * Basically, if NS packet is sent to unicast/anycast addr,
896 	 * target lladdr option SHOULD NOT be included.
897 	 */
898 	if (tlladdr) {
899 		/*
900 		 * sdl0 != NULL indicates proxy NA.  If we do proxy, use
901 		 * lladdr in sdl0.  If we are not proxying (sending NA for
902 		 * my address) use lladdr configured for the interface.
903 		 */
904 		if (sdl0 == NULL) {
905 #ifdef DEV_CARP
906 			if (ifp->if_carp)
907 				mac = carp_macmatch6(ifp->if_carp, m, taddr6);
908 			if (mac == NULL)
909 				mac = nd6_ifptomac(ifp);
910 #else
911 			mac = nd6_ifptomac(ifp);
912 #endif
913 		} else if (sdl0->sa_family == AF_LINK) {
914 			struct sockaddr_dl *sdl;
915 			sdl = (struct sockaddr_dl *)sdl0;
916 			if (sdl->sdl_alen == ifp->if_addrlen)
917 				mac = LLADDR(sdl);
918 		}
919 	}
920 	if (tlladdr && mac) {
921 		int optlen = sizeof(struct nd_opt_hdr) + ifp->if_addrlen;
922 		struct nd_opt_hdr *nd_opt = (struct nd_opt_hdr *)(nd_na + 1);
923 
924 		/* roundup to 8 bytes alignment! */
925 		optlen = (optlen + 7) & ~7;
926 
927 		m->m_pkthdr.len += optlen;
928 		m->m_len += optlen;
929 		icmp6len += optlen;
930 		bzero((caddr_t)nd_opt, optlen);
931 		nd_opt->nd_opt_type = ND_OPT_TARGET_LINKADDR;
932 		nd_opt->nd_opt_len = optlen >> 3;
933 		bcopy(mac, (caddr_t)(nd_opt + 1), ifp->if_addrlen);
934 	} else
935 		flags &= ~ND_NA_FLAG_OVERRIDE;
936 
937 	ip6->ip6_plen = htons((u_short)icmp6len);
938 	nd_na->nd_na_flags_reserved = flags;
939 	nd_na->nd_na_cksum = 0;
940 	nd_na->nd_na_cksum =
941 	    in6_cksum(m, IPPROTO_ICMPV6, sizeof(struct ip6_hdr), icmp6len);
942 
943 	ip6_output(m, NULL, NULL, 0, &im6o, &outif, NULL);
944 	if (outif) {
945 		icmp6_ifstat_inc(outif, ifs6_out_msg);
946 		icmp6_ifstat_inc(outif, ifs6_out_neighboradvert);
947 	}
948 	icmp6stat.icp6s_outhist[ND_NEIGHBOR_ADVERT]++;
949 }
950 
951 caddr_t
952 nd6_ifptomac(ifp)
953 	struct ifnet *ifp;
954 {
955 	switch (ifp->if_type) {
956 	case IFT_ARCNET:
957 	case IFT_ETHER:
958 	case IFT_FDDI:
959 	case IFT_IEEE1394:
960 #ifdef IFT_L2VLAN
961 	case IFT_L2VLAN:
962 #endif
963 #ifdef IFT_IEEE80211
964 	case IFT_IEEE80211:
965 #endif
966 #ifdef IFT_CARP
967 	case IFT_CARP:
968 #endif
969 	case IFT_ISO88025:
970 		return ((caddr_t)(ifp + 1));
971 	default:
972 		return NULL;
973 	}
974 }
975 
976 TAILQ_HEAD(dadq_head, dadq);
977 struct dadq {
978 	TAILQ_ENTRY(dadq) dad_list;
979 	struct ifaddr *dad_ifa;
980 	int dad_count;		/* max NS to send */
981 	int dad_ns_tcount;	/* # of trials to send NS */
982 	int dad_ns_ocount;	/* NS sent so far */
983 	int dad_ns_icount;
984 	int dad_na_icount;
985 	struct callout dad_timer_ch;
986 };
987 
988 static struct dadq_head dadq;
989 static int dad_init = 0;
990 
991 static struct dadq *
992 nd6_dad_find(ifa)
993 	struct ifaddr *ifa;
994 {
995 	struct dadq *dp;
996 
997 	for (dp = dadq.tqh_first; dp; dp = dp->dad_list.tqe_next) {
998 		if (dp->dad_ifa == ifa)
999 			return dp;
1000 	}
1001 	return NULL;
1002 }
1003 
1004 static void
1005 nd6_dad_starttimer(dp, ticks)
1006 	struct dadq *dp;
1007 	int ticks;
1008 {
1009 
1010 	callout_reset(&dp->dad_timer_ch, ticks,
1011 	    (void (*) __P((void *)))nd6_dad_timer, (void *)dp->dad_ifa);
1012 }
1013 
1014 static void
1015 nd6_dad_stoptimer(dp)
1016 	struct dadq *dp;
1017 {
1018 
1019 	callout_stop(&dp->dad_timer_ch);
1020 }
1021 
1022 /*
1023  * Start Duplicated Address Detection (DAD) for specified interface address.
1024  */
1025 void
1026 nd6_dad_start(ifa, tick)
1027 	struct ifaddr *ifa;
1028 	int *tick;	/* minimum delay ticks for IFF_UP event */
1029 {
1030 	struct in6_ifaddr *ia = (struct in6_ifaddr *)ifa;
1031 	struct dadq *dp;
1032 
1033 	if (!dad_init) {
1034 		TAILQ_INIT(&dadq);
1035 		dad_init++;
1036 	}
1037 
1038 	/*
1039 	 * If we don't need DAD, don't do it.
1040 	 * There are several cases:
1041 	 * - DAD is disabled (ip6_dad_count == 0)
1042 	 * - the interface address is anycast
1043 	 */
1044 	if (!(ia->ia6_flags & IN6_IFF_TENTATIVE)) {
1045 		log(LOG_DEBUG,
1046 			"nd6_dad_start: called with non-tentative address "
1047 			"%s(%s)\n",
1048 			ip6_sprintf(&ia->ia_addr.sin6_addr),
1049 			ifa->ifa_ifp ? if_name(ifa->ifa_ifp) : "???");
1050 		return;
1051 	}
1052 	if (ia->ia6_flags & IN6_IFF_ANYCAST) {
1053 		ia->ia6_flags &= ~IN6_IFF_TENTATIVE;
1054 		return;
1055 	}
1056 	if (!ip6_dad_count) {
1057 		ia->ia6_flags &= ~IN6_IFF_TENTATIVE;
1058 		return;
1059 	}
1060 	if (!ifa->ifa_ifp)
1061 		panic("nd6_dad_start: ifa->ifa_ifp == NULL");
1062 	if (!(ifa->ifa_ifp->if_flags & IFF_UP)) {
1063 		return;
1064 	}
1065 	if (nd6_dad_find(ifa) != NULL) {
1066 		/* DAD already in progress */
1067 		return;
1068 	}
1069 
1070 	dp = malloc(sizeof(*dp), M_IP6NDP, M_NOWAIT);
1071 	if (dp == NULL) {
1072 		log(LOG_ERR, "nd6_dad_start: memory allocation failed for "
1073 			"%s(%s)\n",
1074 			ip6_sprintf(&ia->ia_addr.sin6_addr),
1075 			ifa->ifa_ifp ? if_name(ifa->ifa_ifp) : "???");
1076 		return;
1077 	}
1078 	bzero(dp, sizeof(*dp));
1079 	callout_init(&dp->dad_timer_ch, 0);
1080 	TAILQ_INSERT_TAIL(&dadq, (struct dadq *)dp, dad_list);
1081 
1082 	nd6log((LOG_DEBUG, "%s: starting DAD for %s\n", if_name(ifa->ifa_ifp),
1083 	    ip6_sprintf(&ia->ia_addr.sin6_addr)));
1084 
1085 	/*
1086 	 * Send NS packet for DAD, ip6_dad_count times.
1087 	 * Note that we must delay the first transmission, if this is the
1088 	 * first packet to be sent from the interface after interface
1089 	 * (re)initialization.
1090 	 */
1091 	dp->dad_ifa = ifa;
1092 	IFAREF(ifa);	/* just for safety */
1093 	dp->dad_count = ip6_dad_count;
1094 	dp->dad_ns_icount = dp->dad_na_icount = 0;
1095 	dp->dad_ns_ocount = dp->dad_ns_tcount = 0;
1096 	if (tick == NULL) {
1097 		nd6_dad_ns_output(dp, ifa);
1098 		nd6_dad_starttimer(dp,
1099 		    ND_IFINFO(ifa->ifa_ifp)->retrans * hz / 1000);
1100 	} else {
1101 		int ntick;
1102 
1103 		if (*tick == 0)
1104 			ntick = arc4random() % (MAX_RTR_SOLICITATION_DELAY * hz);
1105 		else
1106 			ntick = *tick + arc4random() % (hz / 2);
1107 		*tick = ntick;
1108 		nd6_dad_starttimer(dp, ntick);
1109 	}
1110 }
1111 
1112 /*
1113  * terminate DAD unconditionally.  used for address removals.
1114  */
1115 void
1116 nd6_dad_stop(ifa)
1117 	struct ifaddr *ifa;
1118 {
1119 	struct dadq *dp;
1120 
1121 	if (!dad_init)
1122 		return;
1123 	dp = nd6_dad_find(ifa);
1124 	if (!dp) {
1125 		/* DAD wasn't started yet */
1126 		return;
1127 	}
1128 
1129 	nd6_dad_stoptimer(dp);
1130 
1131 	TAILQ_REMOVE(&dadq, (struct dadq *)dp, dad_list);
1132 	free(dp, M_IP6NDP);
1133 	dp = NULL;
1134 	IFAFREE(ifa);
1135 }
1136 
1137 static void
1138 nd6_dad_timer(ifa)
1139 	struct ifaddr *ifa;
1140 {
1141 	int s;
1142 	struct in6_ifaddr *ia = (struct in6_ifaddr *)ifa;
1143 	struct dadq *dp;
1144 
1145 	s = splnet();		/* XXX */
1146 
1147 	/* Sanity check */
1148 	if (ia == NULL) {
1149 		log(LOG_ERR, "nd6_dad_timer: called with null parameter\n");
1150 		goto done;
1151 	}
1152 	dp = nd6_dad_find(ifa);
1153 	if (dp == NULL) {
1154 		log(LOG_ERR, "nd6_dad_timer: DAD structure not found\n");
1155 		goto done;
1156 	}
1157 	if (ia->ia6_flags & IN6_IFF_DUPLICATED) {
1158 		log(LOG_ERR, "nd6_dad_timer: called with duplicated address "
1159 			"%s(%s)\n",
1160 			ip6_sprintf(&ia->ia_addr.sin6_addr),
1161 			ifa->ifa_ifp ? if_name(ifa->ifa_ifp) : "???");
1162 		goto done;
1163 	}
1164 	if ((ia->ia6_flags & IN6_IFF_TENTATIVE) == 0) {
1165 		log(LOG_ERR, "nd6_dad_timer: called with non-tentative address "
1166 			"%s(%s)\n",
1167 			ip6_sprintf(&ia->ia_addr.sin6_addr),
1168 			ifa->ifa_ifp ? if_name(ifa->ifa_ifp) : "???");
1169 		goto done;
1170 	}
1171 
1172 	/* timeouted with IFF_{RUNNING,UP} check */
1173 	if (dp->dad_ns_tcount > dad_maxtry) {
1174 		nd6log((LOG_INFO, "%s: could not run DAD, driver problem?\n",
1175 		    if_name(ifa->ifa_ifp)));
1176 
1177 		TAILQ_REMOVE(&dadq, (struct dadq *)dp, dad_list);
1178 		free(dp, M_IP6NDP);
1179 		dp = NULL;
1180 		IFAFREE(ifa);
1181 		goto done;
1182 	}
1183 
1184 	/* Need more checks? */
1185 	if (dp->dad_ns_ocount < dp->dad_count) {
1186 		/*
1187 		 * We have more NS to go.  Send NS packet for DAD.
1188 		 */
1189 		nd6_dad_ns_output(dp, ifa);
1190 		nd6_dad_starttimer(dp,
1191 		    ND_IFINFO(ifa->ifa_ifp)->retrans * hz / 1000);
1192 	} else {
1193 		/*
1194 		 * We have transmitted sufficient number of DAD packets.
1195 		 * See what we've got.
1196 		 */
1197 		int duplicate;
1198 
1199 		duplicate = 0;
1200 
1201 		if (dp->dad_na_icount) {
1202 			/*
1203 			 * the check is in nd6_dad_na_input(),
1204 			 * but just in case
1205 			 */
1206 			duplicate++;
1207 		}
1208 
1209 		if (dp->dad_ns_icount) {
1210 #if 0 /* heuristics */
1211 			/*
1212 			 * if
1213 			 * - we have sent many(?) DAD NS, and
1214 			 * - the number of NS we sent equals to the
1215 			 *   number of NS we've got, and
1216 			 * - we've got no NA
1217 			 * we may have a faulty network card/driver which
1218 			 * loops back multicasts to myself.
1219 			 */
1220 			if (3 < dp->dad_count
1221 			 && dp->dad_ns_icount == dp->dad_count
1222 			 && dp->dad_na_icount == 0) {
1223 				log(LOG_INFO, "DAD questionable for %s(%s): "
1224 				    "network card loops back multicast?\n",
1225 				    ip6_sprintf(&ia->ia_addr.sin6_addr),
1226 				    if_name(ifa->ifa_ifp));
1227 				/* XXX consider it a duplicate or not? */
1228 				/* duplicate++; */
1229 			} else {
1230 				/* We've seen NS, means DAD has failed. */
1231 				duplicate++;
1232 			}
1233 #else
1234 			/* We've seen NS, means DAD has failed. */
1235 			duplicate++;
1236 #endif
1237 		}
1238 
1239 		if (duplicate) {
1240 			/* (*dp) will be freed in nd6_dad_duplicated() */
1241 			dp = NULL;
1242 			nd6_dad_duplicated(ifa);
1243 		} else {
1244 			/*
1245 			 * We are done with DAD.  No NA came, no NS came.
1246 			 * duplicated address found.
1247 			 */
1248 			ia->ia6_flags &= ~IN6_IFF_TENTATIVE;
1249 
1250 			nd6log((LOG_DEBUG,
1251 			    "%s: DAD complete for %s - no duplicates found\n",
1252 			    if_name(ifa->ifa_ifp),
1253 			    ip6_sprintf(&ia->ia_addr.sin6_addr)));
1254 
1255 			TAILQ_REMOVE(&dadq, (struct dadq *)dp, dad_list);
1256 			free(dp, M_IP6NDP);
1257 			dp = NULL;
1258 			IFAFREE(ifa);
1259 		}
1260 	}
1261 
1262 done:
1263 	splx(s);
1264 }
1265 
1266 void
1267 nd6_dad_duplicated(ifa)
1268 	struct ifaddr *ifa;
1269 {
1270 	struct in6_ifaddr *ia = (struct in6_ifaddr *)ifa;
1271 	struct dadq *dp;
1272 
1273 	dp = nd6_dad_find(ifa);
1274 	if (dp == NULL) {
1275 		log(LOG_ERR, "nd6_dad_duplicated: DAD structure not found\n");
1276 		return;
1277 	}
1278 
1279 	log(LOG_ERR, "%s: DAD detected duplicate IPv6 address %s: "
1280 	    "NS in/out=%d/%d, NA in=%d\n",
1281 	    if_name(ifa->ifa_ifp), ip6_sprintf(&ia->ia_addr.sin6_addr),
1282 	    dp->dad_ns_icount, dp->dad_ns_ocount, dp->dad_na_icount);
1283 
1284 	ia->ia6_flags &= ~IN6_IFF_TENTATIVE;
1285 	ia->ia6_flags |= IN6_IFF_DUPLICATED;
1286 
1287 	/* We are done with DAD, with duplicated address found. (failure) */
1288 	nd6_dad_stoptimer(dp);
1289 
1290 	log(LOG_ERR, "%s: DAD complete for %s - duplicate found\n",
1291 	    if_name(ifa->ifa_ifp), ip6_sprintf(&ia->ia_addr.sin6_addr));
1292 	log(LOG_ERR, "%s: manual intervention required\n",
1293 	    if_name(ifa->ifa_ifp));
1294 
1295 	TAILQ_REMOVE(&dadq, (struct dadq *)dp, dad_list);
1296 	free(dp, M_IP6NDP);
1297 	dp = NULL;
1298 	IFAFREE(ifa);
1299 }
1300 
1301 static void
1302 nd6_dad_ns_output(dp, ifa)
1303 	struct dadq *dp;
1304 	struct ifaddr *ifa;
1305 {
1306 	struct in6_ifaddr *ia = (struct in6_ifaddr *)ifa;
1307 	struct ifnet *ifp = ifa->ifa_ifp;
1308 
1309 	dp->dad_ns_tcount++;
1310 	if ((ifp->if_flags & IFF_UP) == 0) {
1311 #if 0
1312 		printf("%s: interface down?\n", if_name(ifp));
1313 #endif
1314 		return;
1315 	}
1316 	if ((ifp->if_flags & IFF_RUNNING) == 0) {
1317 #if 0
1318 		printf("%s: interface not running?\n", if_name(ifp));
1319 #endif
1320 		return;
1321 	}
1322 
1323 	dp->dad_ns_ocount++;
1324 	nd6_ns_output(ifp, NULL, &ia->ia_addr.sin6_addr, NULL, 1);
1325 }
1326 
1327 static void
1328 nd6_dad_ns_input(ifa)
1329 	struct ifaddr *ifa;
1330 {
1331 	struct in6_ifaddr *ia;
1332 	struct ifnet *ifp;
1333 	const struct in6_addr *taddr6;
1334 	struct dadq *dp;
1335 	int duplicate;
1336 
1337 	if (!ifa)
1338 		panic("ifa == NULL in nd6_dad_ns_input");
1339 
1340 	ia = (struct in6_ifaddr *)ifa;
1341 	ifp = ifa->ifa_ifp;
1342 	taddr6 = &ia->ia_addr.sin6_addr;
1343 	duplicate = 0;
1344 	dp = nd6_dad_find(ifa);
1345 
1346 	/* Quickhack - completely ignore DAD NS packets */
1347 	if (dad_ignore_ns) {
1348 		nd6log((LOG_INFO,
1349 		    "nd6_dad_ns_input: ignoring DAD NS packet for "
1350 		    "address %s(%s)\n", ip6_sprintf(taddr6),
1351 		    if_name(ifa->ifa_ifp)));
1352 		return;
1353 	}
1354 
1355 	/*
1356 	 * if I'm yet to start DAD, someone else started using this address
1357 	 * first.  I have a duplicate and you win.
1358 	 */
1359 	if (!dp || dp->dad_ns_ocount == 0)
1360 		duplicate++;
1361 
1362 	/* XXX more checks for loopback situation - see nd6_dad_timer too */
1363 
1364 	if (duplicate) {
1365 		dp = NULL;	/* will be freed in nd6_dad_duplicated() */
1366 		nd6_dad_duplicated(ifa);
1367 	} else {
1368 		/*
1369 		 * not sure if I got a duplicate.
1370 		 * increment ns count and see what happens.
1371 		 */
1372 		if (dp)
1373 			dp->dad_ns_icount++;
1374 	}
1375 }
1376 
1377 static void
1378 nd6_dad_na_input(ifa)
1379 	struct ifaddr *ifa;
1380 {
1381 	struct dadq *dp;
1382 
1383 	if (!ifa)
1384 		panic("ifa == NULL in nd6_dad_na_input");
1385 
1386 	dp = nd6_dad_find(ifa);
1387 	if (dp)
1388 		dp->dad_na_icount++;
1389 
1390 	/* remove the address. */
1391 	nd6_dad_duplicated(ifa);
1392 }
1393