name6.c revision 144527
1/*	$KAME: name6.c,v 1.25 2000/06/26 16:44:40 itojun Exp $	*/
2
3/*
4 * Copyright (C) 1995, 1996, 1997, 1998, and 1999 WIDE Project.
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 * 3. Neither the name of the project nor the names of its contributors
16 *    may be used to endorse or promote products derived from this software
17 *    without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 */
31/*
32 * ++Copyright++ 1985, 1988, 1993
33 * -
34 * Copyright (c) 1985, 1988, 1993
35 *    The Regents of the University of California.  All rights reserved.
36 *
37 * Redistribution and use in source and binary forms, with or without
38 * modification, are permitted provided that the following conditions
39 * are met:
40 * 1. Redistributions of source code must retain the above copyright
41 *    notice, this list of conditions and the following disclaimer.
42 * 2. Redistributions in binary form must reproduce the above copyright
43 *    notice, this list of conditions and the following disclaimer in the
44 *    documentation and/or other materials provided with the distribution.
45 * 3. All advertising materials mentioning features or use of this software
46 *    must display the following acknowledgement:
47 * 	This product includes software developed by the University of
48 * 	California, Berkeley and its contributors.
49 * 4. Neither the name of the University nor the names of its contributors
50 *    may be used to endorse or promote products derived from this software
51 *    without specific prior written permission.
52 *
53 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
54 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
55 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
56 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
57 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
58 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
59 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
60 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
61 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
62 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
63 * SUCH DAMAGE.
64 * -
65 * Portions Copyright (c) 1993 by Digital Equipment Corporation.
66 *
67 * Permission to use, copy, modify, and distribute this software for any
68 * purpose with or without fee is hereby granted, provided that the above
69 * copyright notice and this permission notice appear in all copies, and that
70 * the name of Digital Equipment Corporation not be used in advertising or
71 * publicity pertaining to distribution of the document or software without
72 * specific, written prior permission.
73 *
74 * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
75 * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
76 * OF MERCHANTABILITY AND FITNESS.   IN NO EVENT SHALL DIGITAL EQUIPMENT
77 * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
78 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
79 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
80 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
81 * SOFTWARE.
82 * -
83 * --Copyright--
84 */
85
86/*
87 *	Atsushi Onoe <onoe@sm.sony.co.jp>
88 */
89
90/*
91 * TODO for thread safe
92 *	use mutex for _hostconf, _hostconf_init.
93 *	rewrite resolvers to be thread safe
94 */
95
96#include <sys/cdefs.h>
97__FBSDID("$FreeBSD: head/lib/libc/net/name6.c 144527 2005-04-02 08:18:33Z ume $");
98
99#include "namespace.h"
100#include <sys/param.h>
101#include <sys/socket.h>
102#include <sys/time.h>
103#include <sys/queue.h>
104#include <netinet/in.h>
105#ifdef INET6
106#include <net/if.h>
107#include <net/if_var.h>
108#include <sys/sysctl.h>
109#include <sys/ioctl.h>
110#include <netinet6/in6_var.h>	/* XXX */
111#endif
112
113#include <arpa/inet.h>
114#include <arpa/nameser.h>
115
116#include <errno.h>
117#include <netdb.h>
118#include <resolv.h>
119#include <stdio.h>
120#include <stdlib.h>
121#include <string.h>
122#include <stdarg.h>
123#include <nsswitch.h>
124#include <pthread.h>
125#include <unistd.h>
126#include "un-namespace.h"
127
128#ifndef _PATH_HOSTS
129#define	_PATH_HOSTS	"/etc/hosts"
130#endif
131
132#ifndef MAXALIASES
133#define	MAXALIASES	10
134#endif
135#ifndef	MAXADDRS
136#define	MAXADDRS	20
137#endif
138#ifndef MAXDNAME
139#define	MAXDNAME	1025
140#endif
141
142#ifdef INET6
143#define	ADDRLEN(af)	((af) == AF_INET6 ? sizeof(struct in6_addr) : \
144					    sizeof(struct in_addr))
145#else
146#define	ADDRLEN(af)	sizeof(struct in_addr)
147#endif
148
149#define	MAPADDR(ab, ina) \
150do {									\
151	memcpy(&(ab)->map_inaddr, ina, sizeof(struct in_addr));		\
152	memset((ab)->map_zero, 0, sizeof((ab)->map_zero));		\
153	memset((ab)->map_one, 0xff, sizeof((ab)->map_one));		\
154} while (0)
155#define	MAPADDRENABLED(flags) \
156	(((flags) & AI_V4MAPPED) || \
157	 (((flags) & AI_V4MAPPED_CFG) && _mapped_addr_enabled()))
158
159union inx_addr {
160	struct in_addr	in_addr;
161#ifdef INET6
162	struct in6_addr	in6_addr;
163#endif
164	struct {
165		u_char	mau_zero[10];
166		u_char	mau_one[2];
167		struct in_addr mau_inaddr;
168	}		map_addr_un;
169#define	map_zero	map_addr_un.mau_zero
170#define	map_one		map_addr_un.mau_one
171#define	map_inaddr	map_addr_un.mau_inaddr
172};
173
174struct policyqueue {
175	TAILQ_ENTRY(policyqueue) pc_entry;
176#ifdef INET6
177	struct in6_addrpolicy pc_policy;
178#endif
179};
180TAILQ_HEAD(policyhead, policyqueue);
181
182#define AIO_SRCFLAG_DEPRECATED	0x1
183
184struct hp_order {
185	union {
186		struct sockaddr_storage aiou_ss;
187		struct sockaddr aiou_sa;
188	} aio_src_un;
189#define aio_srcsa aio_src_un.aiou_sa
190	u_int32_t aio_srcflag;
191	int aio_srcscope;
192	int aio_dstscope;
193	struct policyqueue *aio_srcpolicy;
194	struct policyqueue *aio_dstpolicy;
195	union {
196		struct sockaddr_storage aiou_ss;
197		struct sockaddr aiou_sa;
198	} aio_un;
199#define aio_sa aio_un.aiou_sa
200	int aio_matchlen;
201	u_char *aio_h_addr;
202};
203
204static struct	 hostent *_hpcopy(struct hostent *hp, int *errp);
205static struct	 hostent *_hpaddr(int af, const char *name, void *addr, int *errp);
206static struct	 hostent *_hpmerge(struct hostent *hp1, struct hostent *hp2, int *errp);
207#ifdef INET6
208static struct	 hostent *_hpmapv6(struct hostent *hp, int *errp);
209#endif
210static struct	 hostent *_hpsort(struct hostent *hp);
211static struct	 hostent *_ghbyname(const char *name, int af, int flags, int *errp);
212static char	*_hgetword(char **pp);
213static int	 _mapped_addr_enabled(void);
214
215static struct	 hostent *_hpreorder(struct hostent *hp);
216static int	 get_addrselectpolicy(struct policyhead *);
217static void	 free_addrselectpolicy(struct policyhead *);
218static struct	 policyqueue *match_addrselectpolicy(struct sockaddr *,
219	struct policyhead *);
220static void	 set_source(struct hp_order *, struct policyhead *);
221static int	 matchlen(struct sockaddr *, struct sockaddr *);
222static int	 comp_dst(const void *, const void *);
223static int	 gai_addr2scopetype(struct sockaddr *);
224
225static FILE	*_files_open(int *errp);
226static int	 _files_ghbyname(void *, void *, va_list);
227static int	 _files_ghbyaddr(void *, void *, va_list);
228#ifdef YP
229static int	 _nis_ghbyname(void *, void *, va_list);
230static int	 _nis_ghbyaddr(void *, void *, va_list);
231#endif
232static int	 _dns_ghbyname(void *, void *, va_list);
233static int	 _dns_ghbyaddr(void *, void *, va_list);
234static void	 _dns_shent(int stayopen) __unused;
235static void	 _dns_ehent(void) __unused;
236#ifdef ICMPNL
237static int	 _icmp_ghbyaddr(void *, void *, va_list);
238#endif /* ICMPNL */
239
240/*
241 * XXX: Many dependencies are not thread-safe.  So, we share lock between
242 * getaddrinfo() and getipnodeby*().  Still, we cannot use
243 * getaddrinfo() and getipnodeby*() in conjunction with other
244 * functions which call them.
245 */
246#include "libc_private.h"
247extern pthread_mutex_t __getaddrinfo_thread_lock;
248#define THREAD_LOCK() \
249	if (__isthreaded) _pthread_mutex_lock(&__getaddrinfo_thread_lock);
250#define THREAD_UNLOCK() \
251	if (__isthreaded) _pthread_mutex_unlock(&__getaddrinfo_thread_lock);
252
253/* Host lookup order if nsswitch.conf is broken or nonexistant */
254static const ns_src default_src[] = {
255	{ NSSRC_FILES, NS_SUCCESS },
256	{ NSSRC_DNS, NS_SUCCESS },
257#ifdef ICMPNL
258#define NSSRC_ICMP "icmp"
259	{ NSSRC_ICMP, NS_SUCCESS },
260#endif
261	{ 0 }
262};
263
264/*
265 * Check if kernel supports mapped address.
266 *	implementation dependent
267 */
268#ifdef __KAME__
269#include <sys/sysctl.h>
270#endif /* __KAME__ */
271
272static int
273_mapped_addr_enabled(void)
274{
275	/* implementation dependent check */
276#if defined(__KAME__) && defined(IPV6CTL_MAPPED_ADDR)
277	int mib[4];
278	size_t len;
279	int val;
280
281	mib[0] = CTL_NET;
282	mib[1] = PF_INET6;
283	mib[2] = IPPROTO_IPV6;
284	mib[3] = IPV6CTL_MAPPED_ADDR;
285	len = sizeof(val);
286	if (sysctl(mib, 4, &val, &len, 0, 0) == 0 && val != 0)
287		return 1;
288#endif /* __KAME__ && IPV6CTL_MAPPED_ADDR */
289	return 0;
290}
291
292/*
293 * Functions defined in RFC2553
294 *	getipnodebyname, getipnodebyaddr, freehostent
295 */
296
297static struct hostent *
298_ghbyname(const char *name, int af, int flags, int *errp)
299{
300	struct hostent *hp;
301	int rval;
302
303	static const ns_dtab dtab[] = {
304		NS_FILES_CB(_files_ghbyname, NULL)
305		{ NSSRC_DNS, _dns_ghbyname, NULL },
306		NS_NIS_CB(_nis_ghbyname, NULL)
307		{ 0 }
308	};
309
310	if (flags & AI_ADDRCONFIG) {
311		int s;
312
313		if ((s = _socket(af, SOCK_DGRAM, 0)) < 0)
314			return NULL;
315		/*
316		 * TODO:
317		 * Note that implementation dependent test for address
318		 * configuration should be done everytime called
319		 * (or apropriate interval),
320		 * because addresses will be dynamically assigned or deleted.
321		 */
322		_close(s);
323	}
324
325	rval = _nsdispatch(&hp, dtab, NSDB_HOSTS, "ghbyname", default_src,
326			  name, af, errp);
327	return (rval == NS_SUCCESS) ? hp : NULL;
328}
329
330struct hostent *
331getipnodebyname(const char *name, int af, int flags, int *errp)
332{
333	struct hostent *hp;
334	union inx_addr addrbuf;
335
336	if (af != AF_INET
337#ifdef INET6
338	    && af != AF_INET6
339#endif
340		)
341	{
342		*errp = NO_RECOVERY;
343		return NULL;
344	}
345
346#ifdef INET6
347	/* special case for literal address */
348	if (inet_pton(AF_INET6, name, &addrbuf) == 1) {
349		if (af != AF_INET6) {
350			*errp = HOST_NOT_FOUND;
351			return NULL;
352		}
353		return _hpaddr(af, name, &addrbuf, errp);
354	}
355#endif
356	if (inet_aton(name, (struct in_addr *)&addrbuf) == 1) {
357		if (af != AF_INET) {
358			if (MAPADDRENABLED(flags)) {
359				MAPADDR(&addrbuf, &addrbuf.in_addr);
360			} else {
361				*errp = HOST_NOT_FOUND;
362				return NULL;
363			}
364		}
365		return _hpaddr(af, name, &addrbuf, errp);
366	}
367
368	*errp = HOST_NOT_FOUND;
369	hp = _ghbyname(name, af, flags, errp);
370
371#ifdef INET6
372	if (af == AF_INET6
373	&&  ((flags & AI_ALL) || hp == NULL)
374	&&  (MAPADDRENABLED(flags))) {
375		struct hostent *hp2 = _ghbyname(name, AF_INET, flags, errp);
376		if (hp == NULL)
377			hp = _hpmapv6(hp2, errp);
378		else {
379			if (hp2 && strcmp(hp->h_name, hp2->h_name) != 0) {
380				freehostent(hp2);
381				hp2 = NULL;
382			}
383			hp = _hpmerge(hp, hp2, errp);
384		}
385	}
386#endif
387	return _hpreorder(_hpsort(hp));
388}
389
390struct hostent *
391getipnodebyaddr(const void *src, size_t len, int af, int *errp)
392{
393	struct hostent *hp;
394	int rval;
395#ifdef INET6
396	struct in6_addr addrbuf;
397#else
398	struct in_addr addrbuf;
399#endif
400
401	static const ns_dtab dtab[] = {
402		NS_FILES_CB(_files_ghbyaddr, NULL)
403		{ NSSRC_DNS, _dns_ghbyaddr, NULL },
404		NS_NIS_CB(_nis_ghbyaddr, NULL)
405#ifdef ICMPNL
406		{ NSSRC_ICMP, _icmp_ghbyaddr, NULL },
407#endif
408		{ 0 }
409	};
410
411	*errp = HOST_NOT_FOUND;
412
413	switch (af) {
414	case AF_INET:
415		if (len != sizeof(struct in_addr)) {
416			*errp = NO_RECOVERY;
417			return NULL;
418		}
419		if ((long)src & ~(sizeof(struct in_addr) - 1)) {
420			memcpy(&addrbuf, src, len);
421			src = &addrbuf;
422		}
423		if (((struct in_addr *)src)->s_addr == 0)
424			return NULL;
425		break;
426#ifdef INET6
427	case AF_INET6:
428		if (len != sizeof(struct in6_addr)) {
429			*errp = NO_RECOVERY;
430			return NULL;
431		}
432		if ((long)src & ~(sizeof(struct in6_addr) / 2 - 1)) {	/*XXX*/
433			memcpy(&addrbuf, src, len);
434			src = &addrbuf;
435		}
436		if (IN6_IS_ADDR_UNSPECIFIED((struct in6_addr *)src))
437			return NULL;
438		if (IN6_IS_ADDR_V4MAPPED((struct in6_addr *)src)
439		||  IN6_IS_ADDR_V4COMPAT((struct in6_addr *)src)) {
440			src = (char *)src +
441			    (sizeof(struct in6_addr) - sizeof(struct in_addr));
442			af = AF_INET;
443			len = sizeof(struct in_addr);
444		}
445		break;
446#endif
447	default:
448		*errp = NO_RECOVERY;
449		return NULL;
450	}
451
452	rval = _nsdispatch(&hp, dtab, NSDB_HOSTS, "ghbyaddr", default_src,
453			  src, len, af, errp);
454	return (rval == NS_SUCCESS) ? hp : NULL;
455}
456
457void
458freehostent(struct hostent *ptr)
459{
460	free(ptr);
461}
462
463#if 0
464
465/* XXX: should be deprecated */
466struct hostent *
467getnodebyname(const char *name, int af, int flags)
468{
469	return getipnodebyname(name, af, flags, &h_errno);
470}
471
472#ifdef __warn_references
473__warn_references(getnodebyname,
474	"warning: getnodebyname() deprecated, "
475	"should use getaddrinfo() or getipnodebyname()");
476#endif
477
478struct hostent *
479getnodebyaddr(const void *src, size_t len, int af)
480{
481	return getipnodebyaddr(src, len, af, &h_errno);
482}
483
484#ifdef __warn_references
485__warn_references(getnodebyaddr,
486	"warning: getnodebyaddr() deprecated, "
487	"should use getnameinfo() or getipnodebyaddr()");
488#endif
489
490#endif
491
492/*
493 * Private utility functions
494 */
495
496/*
497 * _hpcopy: allocate and copy hostent structure
498 */
499static struct hostent *
500_hpcopy(struct hostent *hp, int *errp)
501{
502	struct hostent *nhp;
503	char *cp, **pp;
504	int size, addrsize;
505	int nalias = 0, naddr = 0;
506	int al_off;
507	int i;
508
509	if (hp == NULL)
510		return hp;
511
512	/* count size to be allocated */
513	size = sizeof(struct hostent);
514	if (hp->h_name != NULL)
515		size += strlen(hp->h_name) + 1;
516	if ((pp = hp->h_aliases) != NULL) {
517		for (i = 0; *pp != NULL; i++, pp++) {
518			if (**pp != '\0') {
519				size += strlen(*pp) + 1;
520				nalias++;
521			}
522		}
523	}
524	/* adjust alignment */
525	size = ALIGN(size);
526	al_off = size;
527	size += sizeof(char *) * (nalias + 1);
528	addrsize = ALIGN(hp->h_length);
529	if ((pp = hp->h_addr_list) != NULL) {
530		while (*pp++ != NULL)
531			naddr++;
532	}
533	size += addrsize * naddr;
534	size += sizeof(char *) * (naddr + 1);
535
536	/* copy */
537	if ((nhp = (struct hostent *)malloc(size)) == NULL) {
538		*errp = TRY_AGAIN;
539		return NULL;
540	}
541	cp = (char *)&nhp[1];
542	if (hp->h_name != NULL) {
543		nhp->h_name = cp;
544		strcpy(cp, hp->h_name);
545		cp += strlen(cp) + 1;
546	} else
547		nhp->h_name = NULL;
548	nhp->h_aliases = (char **)((char *)nhp + al_off);
549	if ((pp = hp->h_aliases) != NULL) {
550		for (i = 0; *pp != NULL; pp++) {
551			if (**pp != '\0') {
552				nhp->h_aliases[i++] = cp;
553				strcpy(cp, *pp);
554				cp += strlen(cp) + 1;
555			}
556		}
557	}
558	nhp->h_aliases[nalias] = NULL;
559	cp = (char *)&nhp->h_aliases[nalias + 1];
560	nhp->h_addrtype = hp->h_addrtype;
561	nhp->h_length = hp->h_length;
562	nhp->h_addr_list = (char **)cp;
563	if ((pp = hp->h_addr_list) != NULL) {
564		cp = (char *)&nhp->h_addr_list[naddr + 1];
565		for (i = 0; *pp != NULL; pp++) {
566			nhp->h_addr_list[i++] = cp;
567			memcpy(cp, *pp, hp->h_length);
568			cp += addrsize;
569		}
570	}
571	nhp->h_addr_list[naddr] = NULL;
572	return nhp;
573}
574
575/*
576 * _hpaddr: construct hostent structure with one address
577 */
578static struct hostent *
579_hpaddr(int af, const char *name, void *addr, int *errp)
580{
581	struct hostent *hp, hpbuf;
582	char *addrs[2];
583
584	hp = &hpbuf;
585	hp->h_name = (char *)name;
586	hp->h_aliases = NULL;
587	hp->h_addrtype = af;
588	hp->h_length = ADDRLEN(af);
589	hp->h_addr_list = addrs;
590	addrs[0] = (char *)addr;
591	addrs[1] = NULL;
592	return _hpcopy(hp, errp);
593}
594
595/*
596 * _hpmerge: merge 2 hostent structure, arguments will be freed
597 */
598static struct hostent *
599_hpmerge(struct hostent *hp1, struct hostent *hp2, int *errp)
600{
601	int i, j;
602	int naddr, nalias;
603	char **pp;
604	struct hostent *hp, hpbuf;
605	char *aliases[MAXALIASES + 1], *addrs[MAXADDRS + 1];
606	union inx_addr addrbuf[MAXADDRS];
607
608	if (hp1 == NULL)
609		return hp2;
610	if (hp2 == NULL)
611		return hp1;
612
613#define	HP(i)	(i == 1 ? hp1 : hp2)
614	hp = &hpbuf;
615	hp->h_name = (hp1->h_name != NULL ? hp1->h_name : hp2->h_name);
616	hp->h_aliases = aliases;
617	nalias = 0;
618	for (i = 1; i <= 2; i++) {
619		if ((pp = HP(i)->h_aliases) == NULL)
620			continue;
621		for (; nalias < MAXALIASES && *pp != NULL; pp++) {
622			/* check duplicates */
623			for (j = 0; j < nalias; j++)
624				if (strcasecmp(*pp, aliases[j]) == 0)
625					break;
626			if (j == nalias)
627				aliases[nalias++] = *pp;
628		}
629	}
630	aliases[nalias] = NULL;
631#ifdef INET6
632	if (hp1->h_length != hp2->h_length) {
633		hp->h_addrtype = AF_INET6;
634		hp->h_length = sizeof(struct in6_addr);
635	} else {
636#endif
637		hp->h_addrtype = hp1->h_addrtype;
638		hp->h_length = hp1->h_length;
639#ifdef INET6
640	}
641#endif
642	hp->h_addr_list = addrs;
643	naddr = 0;
644	for (i = 1; i <= 2; i++) {
645		if ((pp = HP(i)->h_addr_list) == NULL)
646			continue;
647		if (HP(i)->h_length == hp->h_length) {
648			while (naddr < MAXADDRS && *pp != NULL)
649				addrs[naddr++] = *pp++;
650		} else {
651			/* copy IPv4 addr as mapped IPv6 addr */
652			while (naddr < MAXADDRS && *pp != NULL) {
653				MAPADDR(&addrbuf[naddr], *pp++);
654				addrs[naddr] = (char *)&addrbuf[naddr];
655				naddr++;
656			}
657		}
658	}
659	addrs[naddr] = NULL;
660	hp = _hpcopy(hp, errp);
661	freehostent(hp1);
662	freehostent(hp2);
663	return hp;
664}
665
666/*
667 * _hpmapv6: convert IPv4 hostent into IPv4-mapped IPv6 addresses
668 */
669#ifdef INET6
670static struct hostent *
671_hpmapv6(struct hostent *hp, int *errp)
672{
673	struct hostent *hp6;
674
675	if (hp == NULL)
676		return NULL;
677	if (hp->h_addrtype == AF_INET6)
678		return hp;
679
680	/* make dummy hostent to convert IPv6 address */
681	if ((hp6 = (struct hostent *)malloc(sizeof(struct hostent))) == NULL) {
682		*errp = TRY_AGAIN;
683		return NULL;
684	}
685	hp6->h_name = NULL;
686	hp6->h_aliases = NULL;
687	hp6->h_addrtype = AF_INET6;
688	hp6->h_length = sizeof(struct in6_addr);
689	hp6->h_addr_list = NULL;
690	return _hpmerge(hp6, hp, errp);
691}
692#endif
693
694/*
695 * _hpsort: sort address by sortlist
696 */
697static struct hostent *
698_hpsort(struct hostent *hp)
699{
700	int i, j, n;
701	u_char *ap, *sp, *mp, **pp;
702	char t;
703	char order[MAXADDRS];
704	int nsort = _res.nsort;
705
706	if (hp == NULL || hp->h_addr_list[1] == NULL || nsort == 0)
707		return hp;
708	for (i = 0; (ap = (u_char *)hp->h_addr_list[i]); i++) {
709		for (j = 0; j < nsort; j++) {
710#ifdef INET6
711			if (_res_ext.sort_list[j].af != hp->h_addrtype)
712				continue;
713			sp = (u_char *)&_res_ext.sort_list[j].addr;
714			mp = (u_char *)&_res_ext.sort_list[j].mask;
715#else
716			sp = (u_char *)&_res.sort_list[j].addr;
717			mp = (u_char *)&_res.sort_list[j].mask;
718#endif
719			for (n = 0; n < hp->h_length; n++) {
720				if ((ap[n] & mp[n]) != sp[n])
721					break;
722			}
723			if (n == hp->h_length)
724				break;
725		}
726		order[i] = j;
727	}
728	n = i;
729	pp = (u_char **)hp->h_addr_list;
730	for (i = 0; i < n - 1; i++) {
731		for (j = i + 1; j < n; j++) {
732			if (order[i] > order[j]) {
733				ap = pp[i];
734				pp[i] = pp[j];
735				pp[j] = ap;
736				t = order[i];
737				order[i] = order[j];
738				order[j] = t;
739			}
740		}
741	}
742	return hp;
743}
744
745static char *
746_hgetword(char **pp)
747{
748	char c, *p, *ret;
749	const char *sp;
750	static const char sep[] = "# \t\n";
751
752	ret = NULL;
753	for (p = *pp; (c = *p) != '\0'; p++) {
754		for (sp = sep; *sp != '\0'; sp++) {
755			if (c == *sp)
756				break;
757		}
758		if (c == '#')
759			p[1] = '\0';	/* ignore rest of line */
760		if (ret == NULL) {
761			if (*sp == '\0')
762				ret = p;
763		} else {
764			if (*sp != '\0') {
765				*p++ = '\0';
766				break;
767			}
768		}
769	}
770	*pp = p;
771	if (ret == NULL || *ret == '\0')
772		return NULL;
773	return ret;
774}
775
776/*
777 * _hpreorder: sort address by default address selection
778 */
779static struct hostent *
780_hpreorder(struct hostent *hp)
781{
782	struct hp_order *aio;
783	int i, n;
784	u_char *ap;
785	struct sockaddr *sa;
786	struct policyhead policyhead;
787
788	if (hp == NULL)
789		return hp;
790
791	switch (hp->h_addrtype) {
792	case AF_INET:
793#ifdef INET6
794	case AF_INET6:
795#endif
796		break;
797	default:
798		free_addrselectpolicy(&policyhead);
799		return hp;
800	}
801
802	/* count the number of addrinfo elements for sorting. */
803	for (n = 0; hp->h_addr_list[n] != NULL; n++)
804		;
805
806	/*
807	 * If the number is small enough, we can skip the reordering process.
808	 */
809	if (n <= 1)
810		return hp;
811
812	/* allocate a temporary array for sort and initialization of it. */
813	if ((aio = malloc(sizeof(*aio) * n)) == NULL)
814		return hp;	/* give up reordering */
815	memset(aio, 0, sizeof(*aio) * n);
816
817	/* retrieve address selection policy from the kernel */
818	TAILQ_INIT(&policyhead);
819	if (!get_addrselectpolicy(&policyhead)) {
820		/* no policy is installed into kernel, we don't sort. */
821		free(aio);
822		return hp;
823	}
824
825	for (i = 0; i < n; i++) {
826		ap = (u_char *)hp->h_addr_list[i];
827		aio[i].aio_h_addr = ap;
828		sa = &aio[i].aio_sa;
829		switch (hp->h_addrtype) {
830		case AF_INET:
831			sa->sa_family = AF_INET;
832			sa->sa_len = sizeof(struct sockaddr_in);
833			memcpy(&((struct sockaddr_in *)sa)->sin_addr, ap,
834			    sizeof(struct in_addr));
835			break;
836#ifdef INET6
837		case AF_INET6:
838			if (IN6_IS_ADDR_V4MAPPED((struct in6_addr *)ap)) {
839				sa->sa_family = AF_INET;
840				sa->sa_len = sizeof(struct sockaddr_in);
841				memcpy(&((struct sockaddr_in *)sa)->sin_addr,
842				    &ap[12], sizeof(struct in_addr));
843			} else {
844				sa->sa_family = AF_INET6;
845				sa->sa_len = sizeof(struct sockaddr_in6);
846				memcpy(&((struct sockaddr_in6 *)sa)->sin6_addr,
847				    ap, sizeof(struct in6_addr));
848			}
849			break;
850#endif
851		}
852		aio[i].aio_dstscope = gai_addr2scopetype(sa);
853		aio[i].aio_dstpolicy = match_addrselectpolicy(sa, &policyhead);
854		set_source(&aio[i], &policyhead);
855	}
856
857	/* perform sorting. */
858	qsort(aio, n, sizeof(*aio), comp_dst);
859
860	/* reorder the h_addr_list. */
861	for (i = 0; i < n; i++)
862		hp->h_addr_list[i] = aio[i].aio_h_addr;
863
864	/* cleanup and return */
865	free(aio);
866	free_addrselectpolicy(&policyhead);
867	return hp;
868}
869
870static int
871get_addrselectpolicy(head)
872	struct policyhead *head;
873{
874#ifdef INET6
875	int mib[] = { CTL_NET, PF_INET6, IPPROTO_IPV6, IPV6CTL_ADDRCTLPOLICY };
876	size_t l;
877	char *buf;
878	struct in6_addrpolicy *pol, *ep;
879
880	if (sysctl(mib, sizeof(mib) / sizeof(mib[0]), NULL, &l, NULL, 0) < 0)
881		return (0);
882	if ((buf = malloc(l)) == NULL)
883		return (0);
884	if (sysctl(mib, sizeof(mib) / sizeof(mib[0]), buf, &l, NULL, 0) < 0) {
885		free(buf);
886		return (0);
887	}
888
889	ep = (struct in6_addrpolicy *)(buf + l);
890	for (pol = (struct in6_addrpolicy *)buf; pol + 1 <= ep; pol++) {
891		struct policyqueue *new;
892
893		if ((new = malloc(sizeof(*new))) == NULL) {
894			free_addrselectpolicy(head); /* make the list empty */
895			break;
896		}
897		new->pc_policy = *pol;
898		TAILQ_INSERT_TAIL(head, new, pc_entry);
899	}
900
901	free(buf);
902	return (1);
903#else
904	return (0);
905#endif
906}
907
908static void
909free_addrselectpolicy(head)
910	struct policyhead *head;
911{
912	struct policyqueue *ent, *nent;
913
914	for (ent = TAILQ_FIRST(head); ent; ent = nent) {
915		nent = TAILQ_NEXT(ent, pc_entry);
916		TAILQ_REMOVE(head, ent, pc_entry);
917		free(ent);
918	}
919}
920
921static struct policyqueue *
922match_addrselectpolicy(addr, head)
923	struct sockaddr *addr;
924	struct policyhead *head;
925{
926#ifdef INET6
927	struct policyqueue *ent, *bestent = NULL;
928	struct in6_addrpolicy *pol;
929	int matchlen, bestmatchlen = -1;
930	u_char *mp, *ep, *k, *p, m;
931	struct sockaddr_in6 key;
932
933	switch(addr->sa_family) {
934	case AF_INET6:
935		key = *(struct sockaddr_in6 *)addr;
936		break;
937	case AF_INET:
938		/* convert the address into IPv4-mapped IPv6 address. */
939		memset(&key, 0, sizeof(key));
940		key.sin6_family = AF_INET6;
941		key.sin6_len = sizeof(key);
942		key.sin6_addr.s6_addr[10] = 0xff;
943		key.sin6_addr.s6_addr[11] = 0xff;
944		memcpy(&key.sin6_addr.s6_addr[12],
945		       &((struct sockaddr_in *)addr)->sin_addr, 4);
946		break;
947	default:
948		return(NULL);
949	}
950
951	for (ent = TAILQ_FIRST(head); ent; ent = TAILQ_NEXT(ent, pc_entry)) {
952		pol = &ent->pc_policy;
953		matchlen = 0;
954
955		mp = (u_char *)&pol->addrmask.sin6_addr;
956		ep = mp + 16;	/* XXX: scope field? */
957		k = (u_char *)&key.sin6_addr;
958		p = (u_char *)&pol->addr.sin6_addr;
959		for (; mp < ep && *mp; mp++, k++, p++) {
960			m = *mp;
961			if ((*k & m) != *p)
962				goto next; /* not match */
963			if (m == 0xff) /* short cut for a typical case */
964				matchlen += 8;
965			else {
966				while (m >= 0x80) {
967					matchlen++;
968					m <<= 1;
969				}
970			}
971		}
972
973		/* matched.  check if this is better than the current best. */
974		if (matchlen > bestmatchlen) {
975			bestent = ent;
976			bestmatchlen = matchlen;
977		}
978
979	  next:
980		continue;
981	}
982
983	return(bestent);
984#else
985	return(NULL);
986#endif
987
988}
989
990static void
991set_source(aio, ph)
992	struct hp_order *aio;
993	struct policyhead *ph;
994{
995	struct sockaddr_storage ss = aio->aio_un.aiou_ss;
996	int s, srclen;
997
998	/* set unspec ("no source is available"), just in case */
999	aio->aio_srcsa.sa_family = AF_UNSPEC;
1000	aio->aio_srcscope = -1;
1001
1002	switch(ss.ss_family) {
1003	case AF_INET:
1004		((struct sockaddr_in *)&ss)->sin_port = htons(1);
1005		break;
1006#ifdef INET6
1007	case AF_INET6:
1008		((struct sockaddr_in6 *)&ss)->sin6_port = htons(1);
1009		break;
1010#endif
1011	default:		/* ignore unsupported AFs explicitly */
1012		return;
1013	}
1014
1015	/* open a socket to get the source address for the given dst */
1016	if ((s = _socket(ss.ss_family, SOCK_DGRAM, IPPROTO_UDP)) < 0)
1017		return;		/* give up */
1018	if (_connect(s, (struct sockaddr *)&ss, ss.ss_len) < 0)
1019		goto cleanup;
1020	srclen = ss.ss_len;
1021	if (_getsockname(s, &aio->aio_srcsa, &srclen) < 0) {
1022		aio->aio_srcsa.sa_family = AF_UNSPEC;
1023		goto cleanup;
1024	}
1025	aio->aio_srcscope = gai_addr2scopetype(&aio->aio_srcsa);
1026	aio->aio_srcpolicy = match_addrselectpolicy(&aio->aio_srcsa, ph);
1027	aio->aio_matchlen = matchlen(&aio->aio_srcsa, (struct sockaddr *)&ss);
1028#ifdef INET6
1029	if (ss.ss_family == AF_INET6) {
1030		struct in6_ifreq ifr6;
1031		u_int32_t flags6;
1032
1033		/* XXX: interface name should not be hardcoded */
1034		strncpy(ifr6.ifr_name, "lo0", sizeof(ifr6.ifr_name));
1035		memset(&ifr6, 0, sizeof(ifr6));
1036		memcpy(&ifr6.ifr_addr, &ss, ss.ss_len);
1037		if (_ioctl(s, SIOCGIFAFLAG_IN6, &ifr6) == 0) {
1038			flags6 = ifr6.ifr_ifru.ifru_flags6;
1039			if ((flags6 & IN6_IFF_DEPRECATED))
1040				aio->aio_srcflag |= AIO_SRCFLAG_DEPRECATED;
1041		}
1042	}
1043#endif
1044
1045  cleanup:
1046	_close(s);
1047	return;
1048}
1049
1050static int
1051matchlen(src, dst)
1052	struct sockaddr *src, *dst;
1053{
1054	int match = 0;
1055	u_char *s, *d;
1056	u_char *lim, r;
1057	int addrlen;
1058
1059	switch (src->sa_family) {
1060#ifdef INET6
1061	case AF_INET6:
1062		s = (u_char *)&((struct sockaddr_in6 *)src)->sin6_addr;
1063		d = (u_char *)&((struct sockaddr_in6 *)dst)->sin6_addr;
1064		addrlen = sizeof(struct in6_addr);
1065		lim = s + addrlen;
1066		break;
1067#endif
1068	case AF_INET:
1069		s = (u_char *)&((struct sockaddr_in6 *)src)->sin6_addr;
1070		d = (u_char *)&((struct sockaddr_in6 *)dst)->sin6_addr;
1071		addrlen = sizeof(struct in_addr);
1072		lim = s + addrlen;
1073		break;
1074	default:
1075		return(0);
1076	}
1077
1078	while (s < lim)
1079		if ((r = (*d++ ^ *s++)) != 0) {
1080			while (r < addrlen * 8) {
1081				match++;
1082				r <<= 1;
1083			}
1084			break;
1085		} else
1086			match += 8;
1087	return(match);
1088}
1089
1090static int
1091comp_dst(arg1, arg2)
1092	const void *arg1, *arg2;
1093{
1094	const struct hp_order *dst1 = arg1, *dst2 = arg2;
1095
1096	/*
1097	 * Rule 1: Avoid unusable destinations.
1098	 * XXX: we currently do not consider if an appropriate route exists.
1099	 */
1100	if (dst1->aio_srcsa.sa_family != AF_UNSPEC &&
1101	    dst2->aio_srcsa.sa_family == AF_UNSPEC) {
1102		return(-1);
1103	}
1104	if (dst1->aio_srcsa.sa_family == AF_UNSPEC &&
1105	    dst2->aio_srcsa.sa_family != AF_UNSPEC) {
1106		return(1);
1107	}
1108
1109	/* Rule 2: Prefer matching scope. */
1110	if (dst1->aio_dstscope == dst1->aio_srcscope &&
1111	    dst2->aio_dstscope != dst2->aio_srcscope) {
1112		return(-1);
1113	}
1114	if (dst1->aio_dstscope != dst1->aio_srcscope &&
1115	    dst2->aio_dstscope == dst2->aio_srcscope) {
1116		return(1);
1117	}
1118
1119	/* Rule 3: Avoid deprecated addresses. */
1120	if (dst1->aio_srcsa.sa_family != AF_UNSPEC &&
1121	    dst2->aio_srcsa.sa_family != AF_UNSPEC) {
1122		if (!(dst1->aio_srcflag & AIO_SRCFLAG_DEPRECATED) &&
1123		    (dst2->aio_srcflag & AIO_SRCFLAG_DEPRECATED)) {
1124			return(-1);
1125		}
1126		if ((dst1->aio_srcflag & AIO_SRCFLAG_DEPRECATED) &&
1127		    !(dst2->aio_srcflag & AIO_SRCFLAG_DEPRECATED)) {
1128			return(1);
1129		}
1130	}
1131
1132	/* Rule 4: Prefer home addresses. */
1133	/* XXX: not implemented yet */
1134
1135	/* Rule 5: Prefer matching label. */
1136#ifdef INET6
1137	if (dst1->aio_srcpolicy && dst1->aio_dstpolicy &&
1138	    dst1->aio_srcpolicy->pc_policy.label ==
1139	    dst1->aio_dstpolicy->pc_policy.label &&
1140	    (dst2->aio_srcpolicy == NULL || dst2->aio_dstpolicy == NULL ||
1141	     dst2->aio_srcpolicy->pc_policy.label !=
1142	     dst2->aio_dstpolicy->pc_policy.label)) {
1143		return(-1);
1144	}
1145	if (dst2->aio_srcpolicy && dst2->aio_dstpolicy &&
1146	    dst2->aio_srcpolicy->pc_policy.label ==
1147	    dst2->aio_dstpolicy->pc_policy.label &&
1148	    (dst1->aio_srcpolicy == NULL || dst1->aio_dstpolicy == NULL ||
1149	     dst1->aio_srcpolicy->pc_policy.label !=
1150	     dst1->aio_dstpolicy->pc_policy.label)) {
1151		return(1);
1152	}
1153#endif
1154
1155	/* Rule 6: Prefer higher precedence. */
1156#ifdef INET6
1157	if (dst1->aio_dstpolicy &&
1158	    (dst2->aio_dstpolicy == NULL ||
1159	     dst1->aio_dstpolicy->pc_policy.preced >
1160	     dst2->aio_dstpolicy->pc_policy.preced)) {
1161		return(-1);
1162	}
1163	if (dst2->aio_dstpolicy &&
1164	    (dst1->aio_dstpolicy == NULL ||
1165	     dst2->aio_dstpolicy->pc_policy.preced >
1166	     dst1->aio_dstpolicy->pc_policy.preced)) {
1167		return(1);
1168	}
1169#endif
1170
1171	/* Rule 7: Prefer native transport. */
1172	/* XXX: not implemented yet */
1173
1174	/* Rule 8: Prefer smaller scope. */
1175	if (dst1->aio_dstscope >= 0 &&
1176	    dst1->aio_dstscope < dst2->aio_dstscope) {
1177		return(-1);
1178	}
1179	if (dst2->aio_dstscope >= 0 &&
1180	    dst2->aio_dstscope < dst1->aio_dstscope) {
1181		return(1);
1182	}
1183
1184	/*
1185	 * Rule 9: Use longest matching prefix.
1186	 * We compare the match length in a same AF only.
1187	 */
1188	if (dst1->aio_sa.sa_family == dst2->aio_sa.sa_family) {
1189		if (dst1->aio_matchlen > dst2->aio_matchlen) {
1190			return(-1);
1191		}
1192		if (dst1->aio_matchlen < dst2->aio_matchlen) {
1193			return(1);
1194		}
1195	}
1196
1197	/* Rule 10: Otherwise, leave the order unchanged. */
1198	return(-1);
1199}
1200
1201/*
1202 * Copy from scope.c.
1203 * XXX: we should standardize the functions and link them as standard
1204 * library.
1205 */
1206static int
1207gai_addr2scopetype(sa)
1208	struct sockaddr *sa;
1209{
1210#ifdef INET6
1211	struct sockaddr_in6 *sa6;
1212#endif
1213	struct sockaddr_in *sa4;
1214
1215	switch(sa->sa_family) {
1216#ifdef INET6
1217	case AF_INET6:
1218		sa6 = (struct sockaddr_in6 *)sa;
1219		if (IN6_IS_ADDR_MULTICAST(&sa6->sin6_addr)) {
1220			/* just use the scope field of the multicast address */
1221			return(sa6->sin6_addr.s6_addr[2] & 0x0f);
1222		}
1223		/*
1224		 * Unicast addresses: map scope type to corresponding scope
1225		 * value defined for multcast addresses.
1226		 * XXX: hardcoded scope type values are bad...
1227		 */
1228		if (IN6_IS_ADDR_LOOPBACK(&sa6->sin6_addr))
1229			return(1); /* node local scope */
1230		if (IN6_IS_ADDR_LINKLOCAL(&sa6->sin6_addr))
1231			return(2); /* link-local scope */
1232		if (IN6_IS_ADDR_SITELOCAL(&sa6->sin6_addr))
1233			return(5); /* site-local scope */
1234		return(14);	/* global scope */
1235		break;
1236#endif
1237	case AF_INET:
1238		/*
1239		 * IPv4 pseudo scoping according to RFC 3484.
1240		 */
1241		sa4 = (struct sockaddr_in *)sa;
1242		/* IPv4 autoconfiguration addresses have link-local scope. */
1243		if (((u_char *)&sa4->sin_addr)[0] == 169 &&
1244		    ((u_char *)&sa4->sin_addr)[1] == 254)
1245			return(2);
1246		/* Private addresses have site-local scope. */
1247		if (((u_char *)&sa4->sin_addr)[0] == 10 ||
1248		    (((u_char *)&sa4->sin_addr)[0] == 172 &&
1249		     (((u_char *)&sa4->sin_addr)[1] & 0xf0) == 16) ||
1250		    (((u_char *)&sa4->sin_addr)[0] == 192 &&
1251		     ((u_char *)&sa4->sin_addr)[1] == 168))
1252			return(14);	/* XXX: It should be 5 unless NAT */
1253		/* Loopback addresses have link-local scope. */
1254		if (((u_char *)&sa4->sin_addr)[0] == 127)
1255			return(2);
1256		return(14);
1257		break;
1258	default:
1259		errno = EAFNOSUPPORT; /* is this a good error? */
1260		return(-1);
1261	}
1262}
1263
1264/*
1265 * FILES (/etc/hosts)
1266 */
1267
1268static FILE *
1269_files_open(int *errp)
1270{
1271	FILE *fp;
1272	fp = fopen(_PATH_HOSTS, "r");
1273	if (fp == NULL)
1274		*errp = NO_RECOVERY;
1275	return fp;
1276}
1277
1278static int
1279_files_ghbyname(void *rval, void *cb_data, va_list ap)
1280{
1281	const char *name;
1282	int af;
1283	int *errp;
1284	int match, nalias;
1285	char *p, *line, *addrstr, *cname;
1286	FILE *fp;
1287	struct hostent *rethp, *hp, hpbuf;
1288	char *aliases[MAXALIASES + 1], *addrs[2];
1289	union inx_addr addrbuf;
1290	char buf[BUFSIZ];
1291
1292	name = va_arg(ap, const char *);
1293	af = va_arg(ap, int);
1294	errp = va_arg(ap, int *);
1295
1296	*(struct hostent **)rval = NULL;
1297
1298	if ((fp = _files_open(errp)) == NULL)
1299		return NS_UNAVAIL;
1300	rethp = hp = NULL;
1301
1302	while (fgets(buf, sizeof(buf), fp)) {
1303		line = buf;
1304		if ((addrstr = _hgetword(&line)) == NULL
1305		||  (cname = _hgetword(&line)) == NULL)
1306			continue;
1307		match = (strcasecmp(cname, name) == 0);
1308		nalias = 0;
1309		while ((p = _hgetword(&line)) != NULL) {
1310			if (!match)
1311				match = (strcasecmp(p, name) == 0);
1312			if (nalias < MAXALIASES)
1313				aliases[nalias++] = p;
1314		}
1315		if (!match)
1316			continue;
1317		switch (af) {
1318		case AF_INET:
1319			if (inet_aton(addrstr, (struct in_addr *)&addrbuf)
1320			    != 1) {
1321				*errp = NO_DATA;	/* name found */
1322				continue;
1323			}
1324			break;
1325#ifdef INET6
1326		case AF_INET6:
1327			if (inet_pton(af, addrstr, &addrbuf) != 1) {
1328				*errp = NO_DATA;	/* name found */
1329				continue;
1330			}
1331			break;
1332#endif
1333		}
1334		hp = &hpbuf;
1335		hp->h_name = cname;
1336		hp->h_aliases = aliases;
1337		aliases[nalias] = NULL;
1338		hp->h_addrtype = af;
1339		hp->h_length = ADDRLEN(af);
1340		hp->h_addr_list = addrs;
1341		addrs[0] = (char *)&addrbuf;
1342		addrs[1] = NULL;
1343		hp = _hpcopy(hp, errp);
1344		rethp = _hpmerge(rethp, hp, errp);
1345	}
1346	fclose(fp);
1347	*(struct hostent **)rval = rethp;
1348	return (rethp != NULL) ? NS_SUCCESS : NS_NOTFOUND;
1349}
1350
1351static int
1352_files_ghbyaddr(void *rval, void *cb_data, va_list ap)
1353{
1354	const void *addr;
1355	int addrlen;
1356	int af;
1357	int *errp;
1358	int nalias;
1359	char *p, *line;
1360	FILE *fp;
1361	struct hostent *hp, hpbuf;
1362	char *aliases[MAXALIASES + 1], *addrs[2];
1363	union inx_addr addrbuf;
1364	char buf[BUFSIZ];
1365
1366	addr = va_arg(ap, const void *);
1367	addrlen = va_arg(ap, int);
1368	af = va_arg(ap, int);
1369	errp = va_arg(ap, int *);
1370
1371	*(struct hostent**)rval = NULL;
1372
1373	if ((fp = _files_open(errp)) == NULL)
1374		return NS_UNAVAIL;
1375	hp = NULL;
1376	while (fgets(buf, sizeof(buf), fp)) {
1377		line = buf;
1378		if ((p = _hgetword(&line)) == NULL
1379		||  (af == AF_INET
1380		     ? inet_aton(p, (struct in_addr *)&addrbuf)
1381		     : inet_pton(af, p, &addrbuf)) != 1
1382		||  memcmp(addr, &addrbuf, addrlen) != 0
1383		||  (p = _hgetword(&line)) == NULL)
1384			continue;
1385		hp = &hpbuf;
1386		hp->h_name = p;
1387		hp->h_aliases = aliases;
1388		nalias = 0;
1389		while ((p = _hgetword(&line)) != NULL) {
1390			if (nalias < MAXALIASES)
1391				aliases[nalias++] = p;
1392		}
1393		aliases[nalias] = NULL;
1394		hp->h_addrtype = af;
1395		hp->h_length = addrlen;
1396		hp->h_addr_list = addrs;
1397		addrs[0] = (char *)&addrbuf;
1398		addrs[1] = NULL;
1399		hp = _hpcopy(hp, errp);
1400		break;
1401	}
1402	fclose(fp);
1403	*(struct hostent **)rval = hp;
1404	return (hp != NULL) ? NS_SUCCESS : NS_NOTFOUND;
1405}
1406
1407#ifdef YP
1408/*
1409 * NIS
1410 *
1411 * XXX actually a hack, these are INET4 specific.
1412 */
1413static int
1414_nis_ghbyname(void *rval, void *cb_data, va_list ap)
1415{
1416	const char *name;
1417	int af;
1418	int *errp;
1419	struct hostent *hp = NULL;
1420
1421	name = va_arg(ap, const char *);
1422	af = va_arg(ap, int);
1423	errp = va_arg(ap, int *);
1424
1425	if (af == AF_INET) {
1426		THREAD_LOCK();
1427		hp = _gethostbynisname(name, af);
1428		if (hp != NULL)
1429			hp = _hpcopy(hp, errp);
1430		THREAD_UNLOCK();
1431	}
1432
1433	*(struct hostent **)rval = hp;
1434	return (hp != NULL) ? NS_SUCCESS : NS_NOTFOUND;
1435
1436}
1437
1438static int
1439_nis_ghbyaddr(void *rval, void *cb_data, va_list ap)
1440{
1441	const void *addr;
1442	int addrlen;
1443	int af;
1444	int *errp;
1445	struct hostent *hp = NULL;
1446
1447	addr = va_arg(ap, const void *);
1448	addrlen = va_arg(ap, int);
1449	af = va_arg(ap, int);
1450
1451	if (af == AF_INET) {
1452		THREAD_LOCK();
1453		hp = _gethostbynisaddr(addr, addrlen, af);
1454		if (hp != NULL)
1455			hp = _hpcopy(hp, errp);
1456		THREAD_UNLOCK();
1457	}
1458	*(struct hostent **)rval = hp;
1459	return (hp != NULL) ? NS_SUCCESS : NS_NOTFOUND;
1460}
1461#endif
1462
1463#define	MAXPACKET	(64*1024)
1464
1465typedef union {
1466	HEADER hdr;
1467	u_char buf[MAXPACKET];
1468} querybuf;
1469
1470static struct hostent *getanswer(const querybuf *, int, const char *, int,
1471	    struct hostent *, int *);
1472
1473/*
1474 * we don't need to take care about sorting, nor IPv4 mapped address here.
1475 */
1476static struct hostent *
1477getanswer(answer, anslen, qname, qtype, template, errp)
1478	const querybuf *answer;
1479	int anslen;
1480	const char *qname;
1481	int qtype;
1482	struct hostent *template;
1483	int *errp;
1484{
1485	const HEADER *hp;
1486	const u_char *cp;
1487	int n;
1488	const u_char *eom, *erdata;
1489	char *bp, *ep, **ap, **hap;
1490	int type, class, ancount, qdcount;
1491	int haveanswer, had_error;
1492	char tbuf[MAXDNAME];
1493	const char *tname;
1494	int (*name_ok)(const char *);
1495	static char *h_addr_ptrs[MAXADDRS + 1];
1496	static char *host_aliases[MAXALIASES];
1497	static char hostbuf[8*1024];
1498
1499#define BOUNDED_INCR(x) \
1500	do { \
1501		cp += x; \
1502		if (cp > eom) { \
1503			*errp = NO_RECOVERY; \
1504			return (NULL); \
1505		} \
1506	} while (0)
1507
1508#define BOUNDS_CHECK(ptr, count) \
1509	do { \
1510		if ((ptr) + (count) > eom) { \
1511			*errp = NO_RECOVERY; \
1512			return (NULL); \
1513		} \
1514	} while (0)
1515
1516/* XXX do {} while (0) cannot be put here */
1517#define DNS_ASSERT(x) \
1518	{				\
1519		if (!(x)) {		\
1520			cp += n;	\
1521			continue;	\
1522		}			\
1523	}
1524
1525/* XXX do {} while (0) cannot be put here */
1526#define DNS_FATAL(x) \
1527	{				\
1528		if (!(x)) {		\
1529			had_error++;	\
1530			continue;	\
1531		}			\
1532	}
1533
1534	tname = qname;
1535	template->h_name = NULL;
1536	eom = answer->buf + anslen;
1537	switch (qtype) {
1538	case T_A:
1539	case T_AAAA:
1540		name_ok = res_hnok;
1541		break;
1542	case T_PTR:
1543		name_ok = res_dnok;
1544		break;
1545	default:
1546		return (NULL);	/* XXX should be abort(); */
1547	}
1548	/*
1549	 * find first satisfactory answer
1550	 */
1551	hp = &answer->hdr;
1552	ancount = ntohs(hp->ancount);
1553	qdcount = ntohs(hp->qdcount);
1554	bp = hostbuf;
1555	ep = hostbuf + sizeof hostbuf;
1556	cp = answer->buf;
1557	BOUNDED_INCR(HFIXEDSZ);
1558	if (qdcount != 1) {
1559		*errp = NO_RECOVERY;
1560		return (NULL);
1561	}
1562	n = dn_expand(answer->buf, eom, cp, bp, ep - bp);
1563	if ((n < 0) || !(*name_ok)(bp)) {
1564		*errp = NO_RECOVERY;
1565		return (NULL);
1566	}
1567	BOUNDED_INCR(n + QFIXEDSZ);
1568	if (qtype == T_A || qtype == T_AAAA) {
1569		/* res_send() has already verified that the query name is the
1570		 * same as the one we sent; this just gets the expanded name
1571		 * (i.e., with the succeeding search-domain tacked on).
1572		 */
1573		n = strlen(bp) + 1;		/* for the \0 */
1574		if (n >= MAXHOSTNAMELEN) {
1575			*errp = NO_RECOVERY;
1576			return (NULL);
1577		}
1578		template->h_name = bp;
1579		bp += n;
1580		/* The qname can be abbreviated, but h_name is now absolute. */
1581		qname = template->h_name;
1582	}
1583	ap = host_aliases;
1584	*ap = NULL;
1585	template->h_aliases = host_aliases;
1586	hap = h_addr_ptrs;
1587	*hap = NULL;
1588	template->h_addr_list = h_addr_ptrs;
1589	haveanswer = 0;
1590	had_error = 0;
1591	while (ancount-- > 0 && cp < eom && !had_error) {
1592		n = dn_expand(answer->buf, eom, cp, bp, ep - bp);
1593		DNS_FATAL(n >= 0);
1594		DNS_FATAL((*name_ok)(bp));
1595		cp += n;			/* name */
1596		BOUNDS_CHECK(cp, 3 * INT16SZ + INT32SZ);
1597		type = _getshort(cp);
1598 		cp += INT16SZ;			/* type */
1599		class = _getshort(cp);
1600 		cp += INT16SZ + INT32SZ;	/* class, TTL */
1601		n = _getshort(cp);
1602		cp += INT16SZ;			/* len */
1603		BOUNDS_CHECK(cp, n);
1604		erdata = cp + n;
1605		DNS_ASSERT(class == C_IN);
1606		if ((qtype == T_A || qtype == T_AAAA) && type == T_CNAME) {
1607			if (ap >= &host_aliases[MAXALIASES-1])
1608				continue;
1609			n = dn_expand(answer->buf, eom, cp, tbuf, sizeof tbuf);
1610			DNS_FATAL(n >= 0);
1611			DNS_FATAL((*name_ok)(tbuf));
1612			cp += n;
1613			if (cp != erdata) {
1614				*errp = NO_RECOVERY;
1615				return (NULL);
1616			}
1617			/* Store alias. */
1618			*ap++ = bp;
1619			n = strlen(bp) + 1;	/* for the \0 */
1620			DNS_FATAL(n < MAXHOSTNAMELEN);
1621			bp += n;
1622			/* Get canonical name. */
1623			n = strlen(tbuf) + 1;	/* for the \0 */
1624			DNS_FATAL(n <= ep - bp);
1625			DNS_FATAL(n < MAXHOSTNAMELEN);
1626			strcpy(bp, tbuf);
1627			template->h_name = bp;
1628			bp += n;
1629			continue;
1630		}
1631		if (qtype == T_PTR && type == T_CNAME) {
1632			n = dn_expand(answer->buf, eom, cp, tbuf, sizeof tbuf);
1633			if (n < 0 || !res_dnok(tbuf)) {
1634				had_error++;
1635				continue;
1636			}
1637			cp += n;
1638			if (cp != erdata) {
1639				*errp = NO_RECOVERY;
1640				return (NULL);
1641			}
1642			/* Get canonical name. */
1643			n = strlen(tbuf) + 1;	/* for the \0 */
1644			if (n > ep - bp || n >= MAXHOSTNAMELEN) {
1645				had_error++;
1646				continue;
1647			}
1648			strcpy(bp, tbuf);
1649			tname = bp;
1650			bp += n;
1651			continue;
1652		}
1653		DNS_ASSERT(type == qtype);
1654		switch (type) {
1655		case T_PTR:
1656			DNS_ASSERT(strcasecmp(tname, bp) == 0);
1657			n = dn_expand(answer->buf, eom, cp, bp, ep - bp);
1658			DNS_FATAL(n >= 0);
1659			DNS_FATAL(res_hnok(bp));
1660#if MULTI_PTRS_ARE_ALIASES
1661			cp += n;
1662			if (cp != erdata) {
1663				*errp = NO_RECOVERY;
1664				return (NULL);
1665			}
1666			if (!haveanswer)
1667				template->h_name = bp;
1668			else if (ap < &host_aliases[MAXALIASES-1])
1669				*ap++ = bp;
1670			else
1671				n = -1;
1672			if (n != -1) {
1673				n = strlen(bp) + 1;	/* for the \0 */
1674				if (n >= MAXHOSTNAMELEN) {
1675					had_error++;
1676					break;
1677				}
1678				bp += n;
1679			}
1680			break;
1681#else
1682			template->h_name = bp;
1683			*errp = NETDB_SUCCESS;
1684			return (template);
1685#endif
1686		case T_A:
1687		case T_AAAA:
1688			DNS_ASSERT(strcasecmp(template->h_name, bp) == 0);
1689			DNS_ASSERT(n == template->h_length);
1690			if (!haveanswer) {
1691				int nn;
1692
1693				template->h_name = bp;
1694				nn = strlen(bp) + 1;	/* for the \0 */
1695				bp += nn;
1696			}
1697			bp = (char *)ALIGN(bp);
1698
1699			DNS_FATAL(bp + n < ep);
1700			DNS_ASSERT(hap < &h_addr_ptrs[MAXADDRS-1]);
1701#ifdef FILTER_V4MAPPED
1702			if (type == T_AAAA) {
1703				struct in6_addr in6;
1704				memcpy(&in6, cp, sizeof(in6));
1705				DNS_ASSERT(IN6_IS_ADDR_V4MAPPED(&in6) == 0);
1706			}
1707#endif
1708			bcopy(cp, *hap++ = bp, n);
1709			bp += n;
1710			cp += n;
1711			if (cp != erdata) {
1712				*errp = NO_RECOVERY;
1713				return (NULL);
1714			}
1715			break;
1716		default:
1717			abort();
1718		}
1719		if (!had_error)
1720			haveanswer++;
1721	}
1722	if (haveanswer) {
1723		*ap = NULL;
1724		*hap = NULL;
1725		if (!template->h_name) {
1726			n = strlen(qname) + 1;	/* for the \0 */
1727			if (n > ep - bp || n >= MAXHOSTNAMELEN)
1728				goto no_recovery;
1729			strcpy(bp, qname);
1730			template->h_name = bp;
1731			bp += n;
1732		}
1733		*errp = NETDB_SUCCESS;
1734		return (template);
1735	}
1736 no_recovery:
1737	*errp = NO_RECOVERY;
1738	return (NULL);
1739
1740#undef BOUNDED_INCR
1741#undef BOUNDS_CHECK
1742#undef DNS_ASSERT
1743#undef DNS_FATAL
1744}
1745
1746static int
1747_dns_ghbyname(void *rval, void *cb_data, va_list ap)
1748{
1749	const char *name;
1750	int af;
1751	int *errp;
1752	int n;
1753	struct hostent *hp;
1754	int qtype;
1755	struct hostent hbuf;
1756	querybuf *buf;
1757
1758	name = va_arg(ap, const char *);
1759	af = va_arg(ap, int);
1760	errp = va_arg(ap, int *);
1761
1762	if ((_res.options & RES_INIT) == 0) {
1763		if (res_init() < 0) {
1764			*errp = h_errno;
1765			return NS_UNAVAIL;
1766		}
1767	}
1768	memset(&hbuf, 0, sizeof(hbuf));
1769	hbuf.h_addrtype = af;
1770	hbuf.h_length = ADDRLEN(af);
1771
1772	switch (af) {
1773#ifdef INET6
1774	case AF_INET6:
1775		qtype = T_AAAA;
1776		break;
1777#endif
1778	case AF_INET:
1779		qtype = T_A;
1780		break;
1781	default:
1782		*errp = NO_RECOVERY;
1783		return NS_NOTFOUND;
1784	}
1785	buf = malloc(sizeof(*buf));
1786	if (buf == NULL) {
1787		*errp = NETDB_INTERNAL;
1788		return NS_UNAVAIL;
1789	}
1790	n = res_search(name, C_IN, qtype, buf->buf, sizeof(buf->buf));
1791	if (n < 0) {
1792		free(buf);
1793		*errp = h_errno;
1794		return NS_UNAVAIL;
1795	}
1796	hp = getanswer(buf, n, name, qtype, &hbuf, errp);
1797	free(buf);
1798	if (!hp) {
1799		*errp = NO_RECOVERY;
1800		return NS_NOTFOUND;
1801	}
1802	*(struct hostent **)rval = _hpcopy(&hbuf, errp);
1803	if (*(struct hostent **)rval != NULL)
1804		return NS_SUCCESS;
1805	else if (*errp == TRY_AGAIN)
1806		return NS_TRYAGAIN;
1807	else
1808		return NS_NOTFOUND;
1809}
1810
1811static int
1812_dns_ghbyaddr(void *rval, void *cb_data, va_list ap)
1813{
1814	const void *addr;
1815	int addrlen;
1816	int af;
1817	int *errp;
1818	int n;
1819	int err;
1820	struct hostent *hp;
1821	u_char c, *cp;
1822	char *bp;
1823	struct hostent hbuf;
1824	int na;
1825#ifdef INET6
1826	static const char hex[] = "0123456789abcdef";
1827#endif
1828	querybuf *buf;
1829	char qbuf[MAXDNAME+1];
1830	char *hlist[2];
1831	char *tld6[] = { "ip6.arpa", NULL };
1832	char *tld4[] = { "in-addr.arpa", NULL };
1833	char **tld;
1834
1835	addr = va_arg(ap, const void *);
1836	addrlen = va_arg(ap, int);
1837	af = va_arg(ap, int);
1838	errp = va_arg(ap, int *);
1839
1840	*(struct hostent **)rval = NULL;
1841
1842#ifdef INET6
1843	/* XXX */
1844	if (af == AF_INET6 && IN6_IS_ADDR_LINKLOCAL((struct in6_addr *)addr))
1845		return NS_NOTFOUND;
1846#endif
1847
1848	switch (af) {
1849#ifdef INET6
1850	case AF_INET6:
1851		tld = tld6;
1852		break;
1853#endif
1854	case AF_INET:
1855		tld = tld4;
1856		break;
1857	default:
1858		return NS_NOTFOUND;
1859	}
1860
1861	if ((_res.options & RES_INIT) == 0) {
1862		if (res_init() < 0) {
1863			*errp = h_errno;
1864			return NS_UNAVAIL;
1865		}
1866	}
1867	memset(&hbuf, 0, sizeof(hbuf));
1868	hbuf.h_name = NULL;
1869	hbuf.h_addrtype = af;
1870	hbuf.h_length = addrlen;
1871	na = 0;
1872
1873	buf = malloc(sizeof(*buf));
1874	if (buf == NULL) {
1875		*errp = NETDB_INTERNAL;
1876		return NS_UNAVAIL;
1877	}
1878	err = NS_SUCCESS;
1879	for (/* nothing */; *tld; tld++) {
1880		/*
1881		 * XXX assumes that MAXDNAME is big enough - error checks
1882		 * has been made by callers
1883		 */
1884		n = 0;
1885		bp = qbuf;
1886		cp = (u_char *)addr+addrlen-1;
1887		switch (af) {
1888#ifdef INET6
1889		case AF_INET6:
1890			for (; n < addrlen; n++, cp--) {
1891				c = *cp;
1892				*bp++ = hex[c & 0xf];
1893				*bp++ = '.';
1894				*bp++ = hex[c >> 4];
1895				*bp++ = '.';
1896			}
1897			strcpy(bp, *tld);
1898			break;
1899#endif
1900		case AF_INET:
1901			for (; n < addrlen; n++, cp--) {
1902				c = *cp;
1903				if (c >= 100)
1904					*bp++ = '0' + c / 100;
1905				if (c >= 10)
1906					*bp++ = '0' + (c % 100) / 10;
1907				*bp++ = '0' + c % 10;
1908				*bp++ = '.';
1909			}
1910			strcpy(bp, *tld);
1911			break;
1912		}
1913
1914		n = res_query(qbuf, C_IN, T_PTR, buf->buf, sizeof buf->buf);
1915		if (n < 0) {
1916			*errp = h_errno;
1917			err = NS_UNAVAIL;
1918			continue;
1919		} else if (n > sizeof(buf->buf)) {
1920#if 0
1921			errno = ERANGE; /* XXX is it OK to set errno here? */
1922#endif
1923			*errp = NETDB_INTERNAL;
1924			err = NS_UNAVAIL;
1925			continue;
1926		}
1927		hp = getanswer(buf, n, qbuf, T_PTR, &hbuf, errp);
1928		if (!hp) {
1929			err = NS_NOTFOUND;
1930			continue;
1931		}
1932		free(buf);
1933		hbuf.h_addrtype = af;
1934		hbuf.h_length = addrlen;
1935		hbuf.h_addr_list = hlist;
1936		hlist[0] = (char *)addr;
1937		hlist[1] = NULL;
1938		*(struct hostent **)rval = _hpcopy(&hbuf, errp);
1939		return NS_SUCCESS;
1940	}
1941	free(buf);
1942	return err;
1943}
1944
1945static void
1946_dns_shent(int stayopen)
1947{
1948	if ((_res.options & RES_INIT) == 0) {
1949		if (res_init() < 0)
1950			return;
1951	}
1952	if (stayopen)
1953		_res.options |= RES_STAYOPEN | RES_USEVC;
1954}
1955
1956static void
1957_dns_ehent(void)
1958{
1959	_res.options &= ~(RES_STAYOPEN | RES_USEVC);
1960	res_close();
1961}
1962
1963#ifdef ICMPNL
1964
1965/*
1966 * experimental:
1967 *	draft-ietf-ipngwg-icmp-namelookups-02.txt
1968 *	ifindex is assumed to be encoded in addr.
1969 */
1970#include <sys/uio.h>
1971#include <netinet/ip6.h>
1972#include <netinet/icmp6.h>
1973
1974struct _icmp_host_cache {
1975	struct _icmp_host_cache *hc_next;
1976	int hc_ifindex;
1977	struct in6_addr hc_addr;
1978	char *hc_name;
1979};
1980
1981static char *
1982_icmp_fqdn_query(const struct in6_addr *addr, int ifindex)
1983{
1984	int s;
1985	struct icmp6_filter filter;
1986	struct msghdr msg;
1987	struct cmsghdr *cmsg;
1988	struct in6_pktinfo *pkt;
1989	char cbuf[256];
1990	char buf[1024];
1991	int cc;
1992	struct icmp6_fqdn_query *fq;
1993	struct icmp6_fqdn_reply *fr;
1994	struct _icmp_host_cache *hc;
1995	struct sockaddr_in6 sin6;
1996	struct iovec iov;
1997	fd_set s_fds, fds;
1998	struct timeval tout;
1999	int len;
2000	char *name;
2001	static struct _icmp_host_cache *hc_head;
2002
2003	THREAD_LOCK();
2004	for (hc = hc_head; hc; hc = hc->hc_next) {
2005		if (hc->hc_ifindex == ifindex
2006		&&  IN6_ARE_ADDR_EQUAL(&hc->hc_addr, addr)) {
2007			THREAD_UNLOCK();
2008			return hc->hc_name;	/* XXX: never freed */
2009		}
2010	}
2011
2012	ICMP6_FILTER_SETBLOCKALL(&filter);
2013	ICMP6_FILTER_SETPASS(ICMP6_FQDN_REPLY, &filter);
2014
2015	FD_ZERO(&s_fds);
2016	tout.tv_sec = 0;
2017	tout.tv_usec = 200000;	/*XXX: 200ms*/
2018
2019	fq = (struct icmp6_fqdn_query *)buf;
2020	fq->icmp6_fqdn_type = ICMP6_FQDN_QUERY;
2021	fq->icmp6_fqdn_code = 0;
2022	fq->icmp6_fqdn_cksum = 0;
2023	fq->icmp6_fqdn_id = (u_short)getpid();
2024	fq->icmp6_fqdn_unused = 0;
2025	fq->icmp6_fqdn_cookie[0] = 0;
2026	fq->icmp6_fqdn_cookie[1] = 0;
2027
2028	memset(&sin6, 0, sizeof(sin6));
2029	sin6.sin6_family = AF_INET6;
2030	sin6.sin6_addr = *addr;
2031
2032	memset(&msg, 0, sizeof(msg));
2033	msg.msg_name = (caddr_t)&sin6;
2034	msg.msg_namelen = sizeof(sin6);
2035	msg.msg_iov = &iov;
2036	msg.msg_iovlen = 1;
2037	msg.msg_control = NULL;
2038	msg.msg_controllen = 0;
2039	iov.iov_base = (caddr_t)buf;
2040	iov.iov_len = sizeof(struct icmp6_fqdn_query);
2041
2042	if (ifindex) {
2043		msg.msg_control = cbuf;
2044		msg.msg_controllen = sizeof(cbuf);
2045		cmsg = CMSG_FIRSTHDR(&msg);
2046		cmsg->cmsg_len = CMSG_LEN(sizeof(struct in6_pktinfo));
2047		cmsg->cmsg_level = IPPROTO_IPV6;
2048		cmsg->cmsg_type = IPV6_PKTINFO;
2049		pkt = (struct in6_pktinfo *)&cmsg[1];
2050		memset(&pkt->ipi6_addr, 0, sizeof(struct in6_addr));
2051		pkt->ipi6_ifindex = ifindex;
2052		cmsg = CMSG_NXTHDR(&msg, cmsg);
2053		msg.msg_controllen = (char *)cmsg - cbuf;
2054	}
2055
2056	if ((s = _socket(PF_INET6, SOCK_RAW, IPPROTO_ICMPV6)) < 0)
2057		return NULL;
2058	(void)_setsockopt(s, IPPROTO_ICMPV6, ICMP6_FILTER,
2059			 (char *)&filter, sizeof(filter));
2060	cc = _sendmsg(s, &msg, 0);
2061	if (cc < 0) {
2062		_close(s);
2063		return NULL;
2064	}
2065	FD_SET(s, &s_fds);
2066	for (;;) {
2067		fds = s_fds;
2068		if (_select(s + 1, &fds, NULL, NULL, &tout) <= 0) {
2069			_close(s);
2070			return NULL;
2071		}
2072		len = sizeof(sin6);
2073		cc = _recvfrom(s, buf, sizeof(buf), 0,
2074			      (struct sockaddr *)&sin6, &len);
2075		if (cc <= 0) {
2076			_close(s);
2077			return NULL;
2078		}
2079		if (cc < sizeof(struct ip6_hdr) + sizeof(struct icmp6_hdr))
2080			continue;
2081		if (!IN6_ARE_ADDR_EQUAL(addr, &sin6.sin6_addr))
2082			continue;
2083		fr = (struct icmp6_fqdn_reply *)(buf + sizeof(struct ip6_hdr));
2084		if (fr->icmp6_fqdn_type == ICMP6_FQDN_REPLY)
2085			break;
2086	}
2087	_close(s);
2088	if (fr->icmp6_fqdn_cookie[1] != 0) {
2089		/* rfc1788 type */
2090		name = buf + sizeof(struct ip6_hdr) + sizeof(struct icmp6_hdr) + 4;
2091		len = (buf + cc) - name;
2092	} else {
2093		len = fr->icmp6_fqdn_namelen;
2094		name = fr->icmp6_fqdn_name;
2095	}
2096	if (len <= 0)
2097		return NULL;
2098	name[len] = 0;
2099
2100	if ((hc = (struct _icmp_host_cache *)malloc(sizeof(*hc))) == NULL)
2101		return NULL;
2102	/* XXX: limit number of cached entries */
2103	hc->hc_ifindex = ifindex;
2104	hc->hc_addr = *addr;
2105	hc->hc_name = strdup(name);
2106	THREAD_LOCK();
2107	hc->hc_next = hc_head;
2108	hc_head = hc;
2109	THREAD_UNLOCK();
2110	return hc->hc_name;
2111}
2112
2113static struct hostent *
2114_icmp_ghbyaddr(const void *addr, int addrlen, int af, int *errp)
2115{
2116	char *hname;
2117	int ifindex;
2118	struct in6_addr addr6;
2119
2120	if (af != AF_INET6) {
2121		/*
2122		 * Note: rfc1788 defines Who Are You for IPv4,
2123		 * but no one implements it.
2124		 */
2125		return NULL;
2126	}
2127
2128	memcpy(&addr6, addr, addrlen);
2129	ifindex = (addr6.s6_addr[2] << 8) | addr6.s6_addr[3];
2130	addr6.s6_addr[2] = addr6.s6_addr[3] = 0;
2131
2132	if (!IN6_IS_ADDR_LINKLOCAL(&addr6))
2133		return NULL;	/*XXX*/
2134
2135	if ((hname = _icmp_fqdn_query(&addr6, ifindex)) == NULL)
2136		return NULL;
2137	return _hpaddr(af, hname, &addr6, errp);
2138}
2139#endif /* ICMPNL */
2140