xref: /netbsd-src/lib/libc/net/getaddrinfo.c (revision 946379e7b37692fc43f68eb0d1c10daa0a7f3b6c)
1 /*	$NetBSD: getaddrinfo.c,v 1.113 2015/12/14 22:07:37 christos Exp $	*/
2 /*	$KAME: getaddrinfo.c,v 1.29 2000/08/31 17:26:57 itojun Exp $	*/
3 
4 /*
5  * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
6  * All rights reserved.
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions
10  * are met:
11  * 1. Redistributions of source code must retain the above copyright
12  *    notice, this list of conditions and the following disclaimer.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in the
15  *    documentation and/or other materials provided with the distribution.
16  * 3. Neither the name of the project nor the names of its contributors
17  *    may be used to endorse or promote products derived from this software
18  *    without specific prior written permission.
19  *
20  * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30  * SUCH DAMAGE.
31  */
32 
33 /*
34  * Issues to be discussed:
35  * - Return values.  There are nonstandard return values defined and used
36  *   in the source code.  This is because RFC2553 is silent about which error
37  *   code must be returned for which situation.
38  * - IPv4 classful (shortened) form.  RFC2553 is silent about it.  XNET 5.2
39  *   says to use inet_aton() to convert IPv4 numeric to binary (alows
40  *   classful form as a result).
41  *   current code - disallow classful form for IPv4 (due to use of inet_pton).
42  * - freeaddrinfo(NULL).  RFC2553 is silent about it.  XNET 5.2 says it is
43  *   invalid.
44  *   current code - SEGV on freeaddrinfo(NULL)
45  * Note:
46  * - The code filters out AFs that are not supported by the kernel,
47  *   when globbing NULL hostname (to loopback, or wildcard).  Is it the right
48  *   thing to do?  What is the relationship with post-RFC2553 AI_ADDRCONFIG
49  *   in ai_flags?
50  * - (post-2553) semantics of AI_ADDRCONFIG itself is too vague.
51  *   (1) what should we do against numeric hostname (2) what should we do
52  *   against NULL hostname (3) what is AI_ADDRCONFIG itself.  AF not ready?
53  *   non-loopback address configured?  global address configured?
54  */
55 
56 #include <sys/cdefs.h>
57 #if defined(LIBC_SCCS) && !defined(lint)
58 __RCSID("$NetBSD: getaddrinfo.c,v 1.113 2015/12/14 22:07:37 christos Exp $");
59 #endif /* LIBC_SCCS and not lint */
60 
61 #ifndef RUMP_ACTION
62 #include "namespace.h"
63 #endif
64 #include <sys/types.h>
65 #include <sys/param.h>
66 #include <sys/socket.h>
67 #include <sys/ioctl.h>
68 #include <sys/sysctl.h>
69 #include <net/if.h>
70 #include <netinet/in.h>
71 #include <netinet6/in6_var.h>
72 #include <arpa/inet.h>
73 #include <arpa/nameser.h>
74 #include <assert.h>
75 #include <ctype.h>
76 #include <errno.h>
77 #include <netdb.h>
78 #include <resolv.h>
79 #include <stddef.h>
80 #include <stdio.h>
81 #include <stdlib.h>
82 #include <string.h>
83 #include <unistd.h>
84 #include <ifaddrs.h>
85 
86 #include <syslog.h>
87 #include <stdarg.h>
88 #include <nsswitch.h>
89 
90 #ifdef YP
91 #include <rpc/rpc.h>
92 #include <rpcsvc/yp_prot.h>
93 #include <rpcsvc/ypclnt.h>
94 #endif
95 
96 #include "servent.h"
97 
98 #ifndef RUMP_ACTION
99 #ifdef __weak_alias
100 __weak_alias(getaddrinfo,_getaddrinfo)
101 __weak_alias(allocaddrinfo,_allocaddrinfo)
102 __weak_alias(freeaddrinfo,_freeaddrinfo)
103 __weak_alias(gai_strerror,_gai_strerror)
104 #endif
105 #endif
106 
107 #define SUCCESS 0
108 #define ANY 0
109 #define YES 1
110 #define NO  0
111 
112 static const char in_addrany[] = { 0, 0, 0, 0 };
113 static const char in_loopback[] = { 127, 0, 0, 1 };
114 #ifdef INET6
115 static const char in6_addrany[] = {
116 	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
117 };
118 static const char in6_loopback[] = {
119 	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1
120 };
121 #endif
122 
123 struct policyqueue {
124 	TAILQ_ENTRY(policyqueue) pc_entry;
125 #ifdef INET6
126 	struct in6_addrpolicy pc_policy;
127 #endif
128 };
129 TAILQ_HEAD(policyhead, policyqueue);
130 
131 static const struct afd {
132 	int a_af;
133 	int a_addrlen;
134 	int a_socklen;
135 	int a_off;
136 	const char *a_addrany;
137 	const char *a_loopback;
138 	int a_scoped;
139 } afdl [] = {
140 #ifdef INET6
141 	{PF_INET6, sizeof(struct in6_addr),
142 	 sizeof(struct sockaddr_in6),
143 	 offsetof(struct sockaddr_in6, sin6_addr),
144 	 in6_addrany, in6_loopback, 1},
145 #endif
146 	{PF_INET, sizeof(struct in_addr),
147 	 sizeof(struct sockaddr_in),
148 	 offsetof(struct sockaddr_in, sin_addr),
149 	 in_addrany, in_loopback, 0},
150 	{0, 0, 0, 0, NULL, NULL, 0},
151 };
152 
153 struct explore {
154 	int e_af;
155 	int e_socktype;
156 	int e_protocol;
157 	const char *e_protostr;
158 	int e_wild;
159 #define WILD_AF(ex)		((ex)->e_wild & 0x01)
160 #define WILD_SOCKTYPE(ex)	((ex)->e_wild & 0x02)
161 #define WILD_PROTOCOL(ex)	((ex)->e_wild & 0x04)
162 };
163 
164 static const struct explore explore[] = {
165 #if 0
166 	{ PF_LOCAL, 0, ANY, ANY, NULL, 0x01 },
167 #endif
168 #ifdef INET6
169 	{ PF_INET6, SOCK_DGRAM, IPPROTO_UDP, "udp", 0x07 },
170 	{ PF_INET6, SOCK_STREAM, IPPROTO_TCP, "tcp", 0x07 },
171 	{ PF_INET6, SOCK_RAW, ANY, NULL, 0x05 },
172 #endif
173 	{ PF_INET, SOCK_DGRAM, IPPROTO_UDP, "udp", 0x07 },
174 	{ PF_INET, SOCK_STREAM, IPPROTO_TCP, "tcp", 0x07 },
175 	{ PF_INET, SOCK_RAW, ANY, NULL, 0x05 },
176 	{ PF_UNSPEC, SOCK_DGRAM, IPPROTO_UDP, "udp", 0x07 },
177 	{ PF_UNSPEC, SOCK_STREAM, IPPROTO_TCP, "tcp", 0x07 },
178 	{ PF_UNSPEC, SOCK_RAW, ANY, NULL, 0x05 },
179 	{ -1, 0, 0, NULL, 0 },
180 };
181 
182 #ifdef INET6
183 #define PTON_MAX	16
184 #else
185 #define PTON_MAX	4
186 #endif
187 
188 #define AIO_SRCFLAG_DEPRECATED	0x1
189 
190 struct ai_order {
191 	union {
192 		struct sockaddr_storage aiou_ss;
193 		struct sockaddr aiou_sa;
194 	} aio_src_un;
195 #define aio_srcsa aio_src_un.aiou_sa
196 	u_int32_t aio_srcflag;
197 	int aio_srcscope;
198 	int aio_dstscope;
199 	struct policyqueue *aio_srcpolicy;
200 	struct policyqueue *aio_dstpolicy;
201 	struct addrinfo *aio_ai;
202 	int aio_matchlen;
203 };
204 
205 static const ns_src default_dns_files[] = {
206 	{ NSSRC_FILES,	NS_SUCCESS },
207 	{ NSSRC_DNS,	NS_SUCCESS },
208 	{ 0, 0 }
209 };
210 
211 #define MAXPACKET	(64*1024)
212 
213 typedef union {
214 	HEADER hdr;
215 	u_char buf[MAXPACKET];
216 } querybuf;
217 
218 struct res_target {
219 	struct res_target *next;
220 	const char *name;	/* domain name */
221 	int qclass, qtype;	/* class and type of query */
222 	u_char *answer;		/* buffer to put answer */
223 	int anslen;		/* size of answer buffer */
224 	int n;			/* result length */
225 };
226 
227 struct srvinfo {
228        struct srvinfo *next;
229        char name[MAXDNAME];
230        int port, pri, weight;
231 };
232 
233 static int gai_srvok(const char *);
234 static int str2number(const char *);
235 static int explore_fqdn(const struct addrinfo *, const char *,
236     const char *, struct addrinfo **, struct servent_data *);
237 static int explore_null(const struct addrinfo *,
238     const char *, struct addrinfo **, struct servent_data *);
239 static int explore_numeric(const struct addrinfo *, const char *,
240     const char *, struct addrinfo **, const char *, struct servent_data *);
241 static int explore_numeric_scope(const struct addrinfo *, const char *,
242     const char *, struct addrinfo **, struct servent_data *);
243 static int get_canonname(const struct addrinfo *,
244     struct addrinfo *, const char *);
245 static struct addrinfo *get_ai(const struct addrinfo *,
246     const struct afd *, const char *);
247 static int get_portmatch(const struct addrinfo *, const char *,
248     struct servent_data *);
249 static int get_port(const struct addrinfo *, const char *, int,
250     struct servent_data *);
251 static const struct afd *find_afd(int);
252 static int addrconfig(uint64_t *);
253 static void set_source(struct ai_order *, struct policyhead *,
254     struct servent_data *);
255 static int comp_dst(const void *, const void *);
256 #ifdef INET6
257 static int ip6_str2scopeid(char *, struct sockaddr_in6 *, u_int32_t *);
258 #endif
259 static int gai_addr2scopetype(struct sockaddr *);
260 
261 static int reorder(struct addrinfo *, struct servent_data *);
262 static int get_addrselectpolicy(struct policyhead *);
263 static void free_addrselectpolicy(struct policyhead *);
264 static struct policyqueue *match_addrselectpolicy(struct sockaddr *,
265 	struct policyhead *);
266 static int matchlen(struct sockaddr *, struct sockaddr *);
267 
268 static struct addrinfo *getanswer(res_state, const querybuf *, int,
269     const char *, int, const struct addrinfo *);
270 static void aisort(struct addrinfo *s, res_state res);
271 static struct addrinfo * _dns_query(struct res_target *,
272     const struct addrinfo *, res_state, int);
273 static struct addrinfo * _dns_srv_lookup(const char *, const char *,
274     const struct addrinfo *);
275 static struct addrinfo * _dns_host_lookup(const char *,
276     const struct addrinfo *);
277 static int _dns_getaddrinfo(void *, void *, va_list);
278 static void _sethtent(FILE **);
279 static void _endhtent(FILE **);
280 static struct addrinfo *_gethtent(FILE **, const char *,
281     const struct addrinfo *);
282 static int _files_getaddrinfo(void *, void *, va_list);
283 #ifdef YP
284 static struct addrinfo *_yphostent(char *, const struct addrinfo *);
285 static int _yp_getaddrinfo(void *, void *, va_list);
286 #endif
287 
288 static int res_queryN(const char *, struct res_target *, res_state);
289 static int res_searchN(const char *, struct res_target *, res_state);
290 static int res_querydomainN(const char *, const char *,
291     struct res_target *, res_state);
292 
293 static const char * const ai_errlist[] = {
294 	"Success",
295 	"Address family for hostname not supported",	/* EAI_ADDRFAMILY */
296 	"Temporary failure in name resolution",		/* EAI_AGAIN	  */
297 	"Invalid value for ai_flags",			/* EAI_BADFLAGS	  */
298 	"Non-recoverable failure in name resolution",	/* EAI_FAIL	  */
299 	"ai_family not supported",			/* EAI_FAMILY	  */
300 	"Memory allocation failure",			/* EAI_MEMORY	  */
301 	"No address associated with hostname",		/* EAI_NODATA	  */
302 	"hostname nor servname provided, or not known", /* EAI_NONAME	  */
303 	"servname not supported for ai_socktype",	/* EAI_SERVICE	  */
304 	"ai_socktype not supported",			/* EAI_SOCKTYPE	  */
305 	"System error returned in errno",		/* EAI_SYSTEM	  */
306 	"Invalid value for hints",			/* EAI_BADHINTS	  */
307 	"Resolved protocol is unknown",			/* EAI_PROTOCOL	  */
308 	"Argument buffer overflow",			/* EAI_OVERFLOW	  */
309 	"Unknown error",				/* EAI_MAX	  */
310 };
311 
312 /* XXX macros that make external reference is BAD. */
313 
314 #define GET_AI(ai, afd, addr)					\
315 do {								\
316 	/* external reference: pai, error, and label free */	\
317 	(ai) = get_ai(pai, (afd), (addr));			\
318 	if ((ai) == NULL) {					\
319 		error = EAI_MEMORY;				\
320 		goto free;					\
321 	}							\
322 } while (/*CONSTCOND*/0)
323 
324 #define GET_PORT(ai, serv, svd)					\
325 do {								\
326 	/* external reference: error and label free */		\
327 	error = get_port((ai), (serv), 0, (svd));		\
328 	if (error != 0)						\
329 		goto free;					\
330 } while (/*CONSTCOND*/0)
331 
332 #define GET_CANONNAME(ai, str)					\
333 do {								\
334 	/* external reference: pai, error and label free */	\
335 	error = get_canonname(pai, (ai), (str));		\
336 	if (error != 0)						\
337 		goto free;					\
338 } while (/*CONSTCOND*/0)
339 
340 #define ERR(err)						\
341 do {								\
342 	/* external reference: error, and label bad */		\
343 	error = (err);						\
344 	goto bad;						\
345 	/*NOTREACHED*/						\
346 } while (/*CONSTCOND*/0)
347 
348 #define MATCH_FAMILY(x, y, w)						\
349 	((x) == (y) || (/*CONSTCOND*/(w) && ((x) == PF_UNSPEC ||	\
350 	    (y) == PF_UNSPEC)))
351 #define MATCH(x, y, w)							\
352 	((x) == (y) || (/*CONSTCOND*/(w) && ((x) == ANY || (y) == ANY)))
353 
354 const char *
355 gai_strerror(int ecode)
356 {
357 	if (ecode < 0 || ecode > EAI_MAX)
358 		ecode = EAI_MAX;
359 	return ai_errlist[ecode];
360 }
361 
362 void
363 freeaddrinfo(struct addrinfo *ai)
364 {
365 	struct addrinfo *next;
366 
367 	_DIAGASSERT(ai != NULL);
368 
369 	do {
370 		next = ai->ai_next;
371 		if (ai->ai_canonname)
372 			free(ai->ai_canonname);
373 		/* no need to free(ai->ai_addr) */
374 		free(ai);
375 		ai = next;
376 	} while (ai);
377 }
378 
379 /*
380  * We don't want localization to affect us
381  */
382 #define PERIOD '.'
383 #define hyphenchar(c) ((c) == '-')
384 #define periodchar(c) ((c) == PERIOD)
385 #define underschar(c) ((c) == '_')
386 #define alphachar(c) (((c) >= 'a' && (c) <= 'z') || ((c) >= 'A' && (c) <= 'Z'))
387 #define digitchar(c) ((c) >= '0' && (c) <= '9')
388 
389 #define firstchar(c)  (alphachar(c) || digitchar(c) || underschar(c))
390 #define lastchar(c)   (alphachar(c) || digitchar(c))
391 #define middlechar(c) (lastchar(c) || hyphenchar(c))
392 
393 static int
394 gai_srvok(const char *dn)
395 {
396 	int nch, pch, ch;
397 
398 	for (pch = PERIOD, nch = ch = *dn++; ch != '\0'; pch = ch, ch = nch) {
399 		if (periodchar(ch))
400 			continue;
401 		if (periodchar(pch)) {
402 			if (!firstchar(ch))
403 				return 0;
404 		} else if (periodchar(nch) || nch == '\0') {
405 			if (!lastchar(ch))
406 				return 0;
407 		} else if (!middlechar(ch))
408 			return 0;
409        }
410        return 1;
411 }
412 
413 static in_port_t *
414 getport(struct addrinfo *ai) {
415 	static in_port_t p;
416 
417 	switch (ai->ai_family) {
418 	case AF_INET:
419 		return &((struct sockaddr_in *)(void *)ai->ai_addr)->sin_port;
420 #ifdef INET6
421 	case AF_INET6:
422 		return &((struct sockaddr_in6 *)(void *)ai->ai_addr)->sin6_port;
423 #endif
424 	default:
425 		p = 0;
426 		/* XXX: abort()? */
427 		return &p;
428 	}
429 }
430 
431 static int
432 str2number(const char *p)
433 {
434 	char *ep;
435 	unsigned long v;
436 
437 	_DIAGASSERT(p != NULL);
438 
439 	if (*p == '\0')
440 		return -1;
441 	ep = NULL;
442 	errno = 0;
443 	v = strtoul(p, &ep, 10);
444 	if (errno == 0 && ep && *ep == '\0' && v <= INT_MAX)
445 		return (int)v;
446 	else
447 		return -1;
448 }
449 
450 int
451 getaddrinfo(const char *hostname, const char *servname,
452     const struct addrinfo *hints, struct addrinfo **res)
453 {
454 	struct addrinfo sentinel;
455 	struct addrinfo *cur;
456 	int error = 0;
457 	struct addrinfo ai;
458 	struct addrinfo ai0;
459 	struct addrinfo *pai;
460 	const struct explore *ex;
461 	struct servent_data svd;
462 	uint64_t mask = (uint64_t)~0ULL;
463 	int numeric = 0;
464 
465 	/* hostname is allowed to be NULL */
466 	/* servname is allowed to be NULL */
467 	/* hints is allowed to be NULL */
468 	_DIAGASSERT(res != NULL);
469 
470 	(void)memset(&svd, 0, sizeof(svd));
471 	memset(&sentinel, 0, sizeof(sentinel));
472 	cur = &sentinel;
473 	memset(&ai, 0, sizeof(ai));
474 	pai = &ai;
475 	pai->ai_flags = 0;
476 	pai->ai_family = PF_UNSPEC;
477 	pai->ai_socktype = ANY;
478 	pai->ai_protocol = ANY;
479 	pai->ai_addrlen = 0;
480 	pai->ai_canonname = NULL;
481 	pai->ai_addr = NULL;
482 	pai->ai_next = NULL;
483 
484 	if (hostname == NULL && servname == NULL)
485 		return EAI_NONAME;
486 	if (hints) {
487 		/* error check for hints */
488 		if (hints->ai_addrlen || hints->ai_canonname ||
489 		    hints->ai_addr || hints->ai_next)
490 			ERR(EAI_BADHINTS); /* xxx */
491 		if (hints->ai_flags & ~AI_MASK)
492 			ERR(EAI_BADFLAGS);
493 		switch (hints->ai_family) {
494 		case PF_UNSPEC:
495 		case PF_INET:
496 #ifdef INET6
497 		case PF_INET6:
498 #endif
499 			break;
500 		default:
501 			ERR(EAI_FAMILY);
502 		}
503 		memcpy(pai, hints, sizeof(*pai));
504 
505 		/*
506 		 * if both socktype/protocol are specified, check if they
507 		 * are meaningful combination.
508 		 */
509 		if (pai->ai_socktype != ANY && pai->ai_protocol != ANY) {
510 			for (ex = explore; ex->e_af >= 0; ex++) {
511 				if (pai->ai_family != ex->e_af)
512 					continue;
513 				if (ex->e_socktype == ANY)
514 					continue;
515 				if (ex->e_protocol == ANY)
516 					continue;
517 				if (pai->ai_socktype == ex->e_socktype
518 				 && pai->ai_protocol != ex->e_protocol) {
519 					ERR(EAI_BADHINTS);
520 				}
521 			}
522 		}
523 	}
524 
525 	if ((pai->ai_flags & AI_ADDRCONFIG) != 0 && addrconfig(&mask) == -1)
526 		ERR(EAI_FAIL);
527 
528 	/*
529 	 * check for special cases.  (1) numeric servname is disallowed if
530 	 * socktype/protocol are left unspecified. (2) servname is disallowed
531 	 * for raw and other inet{,6} sockets.
532 	 */
533 	if (MATCH_FAMILY(pai->ai_family, PF_INET, 1)
534 #ifdef PF_INET6
535 	 || MATCH_FAMILY(pai->ai_family, PF_INET6, 1)
536 #endif
537 	    ) {
538 		ai0 = *pai;	/* backup *pai */
539 
540 		if (pai->ai_family == PF_UNSPEC) {
541 #ifdef PF_INET6
542 			pai->ai_family = PF_INET6;
543 #else
544 			pai->ai_family = PF_INET;
545 #endif
546 		}
547 		error = get_portmatch(pai, servname, &svd);
548 		if (error)
549 			goto bad;
550 
551 		*pai = ai0;
552 	}
553 
554 	ai0 = *pai;
555 
556 	/* NULL hostname, or numeric hostname */
557 	for (ex = explore; ex->e_af >= 0; ex++) {
558 		*pai = ai0;
559 
560 		/* ADDRCONFIG check */
561 		if ((((uint64_t)1 << ex->e_af) & mask) == 0)
562 			continue;
563 
564 		/* PF_UNSPEC entries are prepared for DNS queries only */
565 		if (ex->e_af == PF_UNSPEC)
566 			continue;
567 
568 		if (!MATCH_FAMILY(pai->ai_family, ex->e_af, WILD_AF(ex)))
569 			continue;
570 		if (!MATCH(pai->ai_socktype, ex->e_socktype, WILD_SOCKTYPE(ex)))
571 			continue;
572 		if (!MATCH(pai->ai_protocol, ex->e_protocol, WILD_PROTOCOL(ex)))
573 			continue;
574 		if (pai->ai_family == PF_UNSPEC)
575 			pai->ai_family = ex->e_af;
576 		if (pai->ai_socktype == ANY && ex->e_socktype != ANY)
577 			pai->ai_socktype = ex->e_socktype;
578 		if (pai->ai_protocol == ANY && ex->e_protocol != ANY)
579 			pai->ai_protocol = ex->e_protocol;
580 
581 		if (hostname == NULL)
582 			error = explore_null(pai, servname, &cur->ai_next,
583 			    &svd);
584 		else
585 			error = explore_numeric_scope(pai, hostname, servname,
586 			    &cur->ai_next, &svd);
587 
588 		if (error)
589 			goto free;
590 
591 		while (cur->ai_next)
592 			cur = cur->ai_next;
593 	}
594 
595 	/*
596 	 * XXX
597 	 * If numeric representation of AF1 can be interpreted as FQDN
598 	 * representation of AF2, we need to think again about the code below.
599 	 */
600 	if (sentinel.ai_next) {
601 		numeric = 1;
602 		goto good;
603 	}
604 
605 	if (hostname == NULL)
606 		ERR(EAI_NODATA);
607 	if (pai->ai_flags & AI_NUMERICHOST)
608 		ERR(EAI_NONAME);
609 
610 	/*
611 	 * hostname as alphabetical name.
612 	 * we would like to prefer AF_INET6 than AF_INET, so we'll make a
613 	 * outer loop by AFs.
614 	 */
615 	for (ex = explore; ex->e_af >= 0; ex++) {
616 		*pai = ai0;
617 
618 
619 		/* ADDRCONFIG check */
620 		/* PF_UNSPEC entries are prepared for DNS queries only */
621 		if (ex->e_af != PF_UNSPEC &&
622 		    (((uint64_t)1 << ex->e_af) & mask) == 0)
623 			continue;
624 
625 		/* require exact match for family field */
626 		if (pai->ai_family != ex->e_af)
627 			continue;
628 
629 		if (!MATCH(pai->ai_socktype, ex->e_socktype,
630 				WILD_SOCKTYPE(ex))) {
631 			continue;
632 		}
633 		if (!MATCH(pai->ai_protocol, ex->e_protocol,
634 				WILD_PROTOCOL(ex))) {
635 			continue;
636 		}
637 
638 		if (pai->ai_socktype == ANY && ex->e_socktype != ANY)
639 			pai->ai_socktype = ex->e_socktype;
640 		if (pai->ai_protocol == ANY && ex->e_protocol != ANY)
641 			pai->ai_protocol = ex->e_protocol;
642 
643 		error = explore_fqdn(pai, hostname, servname, &cur->ai_next,
644 		    &svd);
645 
646 		while (cur && cur->ai_next)
647 			cur = cur->ai_next;
648 	}
649 
650 	/* XXX */
651 	if (sentinel.ai_next)
652 		error = 0;
653 
654 	if (error)
655 		goto free;
656 
657 	if (sentinel.ai_next) {
658  good:
659 		/*
660 		 * If the returned entry is for an active connection,
661 		 * and the given name is not numeric, reorder the
662 		 * list, so that the application would try the list
663 		 * in the most efficient order.  Since the head entry
664 		 * of the original list may contain ai_canonname and
665 		 * that entry may be moved elsewhere in the new list,
666 		 * we keep the pointer and will  restore it in the new
667 		 * head entry.  (Note that RFC3493 requires the head
668 		 * entry store it when requested by the caller).
669 		 */
670 		if (hints == NULL || !(hints->ai_flags & AI_PASSIVE)) {
671 			if (!numeric) {
672 				char *canonname;
673 
674 				canonname = sentinel.ai_next->ai_canonname;
675 				sentinel.ai_next->ai_canonname = NULL;
676 				(void)reorder(&sentinel, &svd);
677 				if (sentinel.ai_next->ai_canonname == NULL) {
678 					sentinel.ai_next->ai_canonname
679 					    = canonname;
680 				} else if (canonname != NULL)
681 					free(canonname);
682 			}
683 		}
684 		endservent_r(&svd);
685 		*res = sentinel.ai_next;
686 		return SUCCESS;
687 	} else
688 		error = EAI_FAIL;
689  free:
690  bad:
691 	endservent_r(&svd);
692 	if (sentinel.ai_next)
693 		freeaddrinfo(sentinel.ai_next);
694 	*res = NULL;
695 	return error;
696 }
697 
698 static int
699 reorder(struct addrinfo *sentinel, struct servent_data *svd)
700 {
701 	struct addrinfo *ai, **aip;
702 	struct ai_order *aio;
703 	int i, n;
704 	struct policyhead policyhead;
705 
706 	/* count the number of addrinfo elements for sorting. */
707 	for (n = 0, ai = sentinel->ai_next; ai != NULL; ai = ai->ai_next, n++)
708 		;
709 
710 	/*
711 	 * If the number is small enough, we can skip the reordering process.
712 	 */
713 	if (n <= 1)
714 		return(n);
715 
716 	/* allocate a temporary array for sort and initialization of it. */
717 	if ((aio = malloc(sizeof(*aio) * n)) == NULL)
718 		return(n);	/* give up reordering */
719 	memset(aio, 0, sizeof(*aio) * n);
720 
721 	/* retrieve address selection policy from the kernel */
722 	TAILQ_INIT(&policyhead);
723 	if (!get_addrselectpolicy(&policyhead)) {
724 		/* no policy is installed into kernel, we don't sort. */
725 		free(aio);
726 		return (n);
727 	}
728 
729 	for (i = 0, ai = sentinel->ai_next; i < n; ai = ai->ai_next, i++) {
730 		aio[i].aio_ai = ai;
731 		aio[i].aio_dstscope = gai_addr2scopetype(ai->ai_addr);
732 		aio[i].aio_dstpolicy = match_addrselectpolicy(ai->ai_addr,
733 							      &policyhead);
734 		set_source(&aio[i], &policyhead, svd);
735 	}
736 
737 	/* perform sorting. */
738 	qsort(aio, n, sizeof(*aio), comp_dst);
739 
740 	/* reorder the addrinfo chain. */
741 	for (i = 0, aip = &sentinel->ai_next; i < n; i++) {
742 		*aip = aio[i].aio_ai;
743 		aip = &aio[i].aio_ai->ai_next;
744 	}
745 	*aip = NULL;
746 
747 	/* cleanup and return */
748 	free(aio);
749 	free_addrselectpolicy(&policyhead);
750 	return(n);
751 }
752 
753 static int
754 get_addrselectpolicy(struct policyhead *head)
755 {
756 #ifdef INET6
757 	int mib[] = { CTL_NET, PF_INET6, IPPROTO_IPV6, IPV6CTL_ADDRCTLPOLICY };
758 	size_t l;
759 	char *buf;
760 	struct in6_addrpolicy *pol, *ep;
761 
762 	if (sysctl(mib, sizeof(mib) / sizeof(mib[0]), NULL, &l, NULL, 0) < 0)
763 		return (0);
764 	if (l == 0)
765 		return (0);
766 	if ((buf = malloc(l)) == NULL)
767 		return (0);
768 	if (sysctl(mib, sizeof(mib) / sizeof(mib[0]), buf, &l, NULL, 0) < 0) {
769 		free(buf);
770 		return (0);
771 	}
772 
773 	ep = (struct in6_addrpolicy *)(buf + l);
774 	for (pol = (struct in6_addrpolicy *)buf; pol + 1 <= ep; pol++) {
775 		struct policyqueue *new;
776 
777 		if ((new = malloc(sizeof(*new))) == NULL) {
778 			free_addrselectpolicy(head); /* make the list empty */
779 			break;
780 		}
781 		new->pc_policy = *pol;
782 		TAILQ_INSERT_TAIL(head, new, pc_entry);
783 	}
784 
785 	free(buf);
786 	return (1);
787 #else
788 	return (0);
789 #endif
790 }
791 
792 static void
793 free_addrselectpolicy(struct policyhead *head)
794 {
795 	struct policyqueue *ent, *nent;
796 
797 	for (ent = TAILQ_FIRST(head); ent; ent = nent) {
798 		nent = TAILQ_NEXT(ent, pc_entry);
799 		TAILQ_REMOVE(head, ent, pc_entry);
800 		free(ent);
801 	}
802 }
803 
804 static struct policyqueue *
805 match_addrselectpolicy(struct sockaddr *addr, struct policyhead *head)
806 {
807 #ifdef INET6
808 	struct policyqueue *ent, *bestent = NULL;
809 	struct in6_addrpolicy *pol;
810 	int matchlen, bestmatchlen = -1;
811 	u_char *mp, *ep, *k, *p, m;
812 	struct sockaddr_in6 key;
813 
814 	switch(addr->sa_family) {
815 	case AF_INET6:
816 		key = *(struct sockaddr_in6 *)addr;
817 		break;
818 	case AF_INET:
819 		/* convert the address into IPv4-mapped IPv6 address. */
820 		memset(&key, 0, sizeof(key));
821 		key.sin6_family = AF_INET6;
822 		key.sin6_len = sizeof(key);
823 		key.sin6_addr.s6_addr[10] = 0xff;
824 		key.sin6_addr.s6_addr[11] = 0xff;
825 		memcpy(&key.sin6_addr.s6_addr[12],
826 		       &((struct sockaddr_in *)addr)->sin_addr, 4);
827 		break;
828 	default:
829 		return(NULL);
830 	}
831 
832 	for (ent = TAILQ_FIRST(head); ent; ent = TAILQ_NEXT(ent, pc_entry)) {
833 		pol = &ent->pc_policy;
834 		matchlen = 0;
835 
836 		mp = (u_char *)&pol->addrmask.sin6_addr;
837 		ep = mp + 16;	/* XXX: scope field? */
838 		k = (u_char *)&key.sin6_addr;
839 		p = (u_char *)&pol->addr.sin6_addr;
840 		for (; mp < ep && *mp; mp++, k++, p++) {
841 			m = *mp;
842 			if ((*k & m) != *p)
843 				goto next; /* not match */
844 			if (m == 0xff) /* short cut for a typical case */
845 				matchlen += 8;
846 			else {
847 				while (m >= 0x80) {
848 					matchlen++;
849 					m <<= 1;
850 				}
851 			}
852 		}
853 
854 		/* matched.  check if this is better than the current best. */
855 		if (matchlen > bestmatchlen) {
856 			bestent = ent;
857 			bestmatchlen = matchlen;
858 		}
859 
860 	  next:
861 		continue;
862 	}
863 
864 	return(bestent);
865 #else
866 	return(NULL);
867 #endif
868 
869 }
870 
871 static void
872 set_source(struct ai_order *aio, struct policyhead *ph,
873     struct servent_data *svd)
874 {
875 	struct addrinfo ai = *aio->aio_ai;
876 	struct sockaddr_storage ss;
877 	socklen_t srclen;
878 	int s;
879 
880 	/* set unspec ("no source is available"), just in case */
881 	aio->aio_srcsa.sa_family = AF_UNSPEC;
882 	aio->aio_srcscope = -1;
883 
884 	switch(ai.ai_family) {
885 	case AF_INET:
886 #ifdef INET6
887 	case AF_INET6:
888 #endif
889 		break;
890 	default:		/* ignore unsupported AFs explicitly */
891 		return;
892 	}
893 
894 	/* XXX: make a dummy addrinfo to call connect() */
895 	ai.ai_socktype = SOCK_DGRAM;
896 	ai.ai_protocol = IPPROTO_UDP; /* is UDP too specific? */
897 	ai.ai_next = NULL;
898 	memset(&ss, 0, sizeof(ss));
899 	memcpy(&ss, ai.ai_addr, ai.ai_addrlen);
900 	ai.ai_addr = (struct sockaddr *)&ss;
901 	get_port(&ai, "1", 0, svd);
902 
903 	/* open a socket to get the source address for the given dst */
904 	if ((s = socket(ai.ai_family, ai.ai_socktype | SOCK_CLOEXEC,
905 	    ai.ai_protocol)) < 0)
906 		return;		/* give up */
907 	if (connect(s, ai.ai_addr, ai.ai_addrlen) < 0)
908 		goto cleanup;
909 	srclen = ai.ai_addrlen;
910 	if (getsockname(s, &aio->aio_srcsa, &srclen) < 0) {
911 		aio->aio_srcsa.sa_family = AF_UNSPEC;
912 		goto cleanup;
913 	}
914 	aio->aio_srcscope = gai_addr2scopetype(&aio->aio_srcsa);
915 	aio->aio_srcpolicy = match_addrselectpolicy(&aio->aio_srcsa, ph);
916 	aio->aio_matchlen = matchlen(&aio->aio_srcsa, aio->aio_ai->ai_addr);
917 #ifdef INET6
918 	if (ai.ai_family == AF_INET6) {
919 		struct in6_ifreq ifr6;
920 		u_int32_t flags6;
921 
922 		memset(&ifr6, 0, sizeof(ifr6));
923 		memcpy(&ifr6.ifr_addr, ai.ai_addr, ai.ai_addrlen);
924 		if (ioctl(s, SIOCGIFAFLAG_IN6, &ifr6) == 0) {
925 			flags6 = ifr6.ifr_ifru.ifru_flags6;
926 			if ((flags6 & IN6_IFF_DEPRECATED))
927 				aio->aio_srcflag |= AIO_SRCFLAG_DEPRECATED;
928 		}
929 	}
930 #endif
931 
932   cleanup:
933 	close(s);
934 	return;
935 }
936 
937 static int
938 matchlen(struct sockaddr *src, struct sockaddr *dst)
939 {
940 	int match = 0;
941 	u_char *s, *d;
942 	u_char *lim, r;
943 	int addrlen;
944 
945 	switch (src->sa_family) {
946 #ifdef INET6
947 	case AF_INET6:
948 		s = (u_char *)&((struct sockaddr_in6 *)src)->sin6_addr;
949 		d = (u_char *)&((struct sockaddr_in6 *)dst)->sin6_addr;
950 		addrlen = sizeof(struct in6_addr);
951 		lim = s + addrlen;
952 		break;
953 #endif
954 	case AF_INET:
955 		s = (u_char *)&((struct sockaddr_in *)src)->sin_addr;
956 		d = (u_char *)&((struct sockaddr_in *)dst)->sin_addr;
957 		addrlen = sizeof(struct in_addr);
958 		lim = s + addrlen;
959 		break;
960 	default:
961 		return(0);
962 	}
963 
964 	while (s < lim)
965 		if ((r = (*d++ ^ *s++)) != 0) {
966 			while (r < addrlen * 8) {
967 				match++;
968 				r <<= 1;
969 			}
970 			break;
971 		} else
972 			match += 8;
973 	return(match);
974 }
975 
976 static int
977 comp_dst(const void *arg1, const void *arg2)
978 {
979 	const struct ai_order *dst1 = arg1, *dst2 = arg2;
980 
981 	/*
982 	 * Rule 1: Avoid unusable destinations.
983 	 * XXX: we currently do not consider if an appropriate route exists.
984 	 */
985 	if (dst1->aio_srcsa.sa_family != AF_UNSPEC &&
986 	    dst2->aio_srcsa.sa_family == AF_UNSPEC) {
987 		return(-1);
988 	}
989 	if (dst1->aio_srcsa.sa_family == AF_UNSPEC &&
990 	    dst2->aio_srcsa.sa_family != AF_UNSPEC) {
991 		return(1);
992 	}
993 
994 	/* Rule 2: Prefer matching scope. */
995 	if (dst1->aio_dstscope == dst1->aio_srcscope &&
996 	    dst2->aio_dstscope != dst2->aio_srcscope) {
997 		return(-1);
998 	}
999 	if (dst1->aio_dstscope != dst1->aio_srcscope &&
1000 	    dst2->aio_dstscope == dst2->aio_srcscope) {
1001 		return(1);
1002 	}
1003 
1004 	/* Rule 3: Avoid deprecated addresses. */
1005 	if (dst1->aio_srcsa.sa_family != AF_UNSPEC &&
1006 	    dst2->aio_srcsa.sa_family != AF_UNSPEC) {
1007 		if (!(dst1->aio_srcflag & AIO_SRCFLAG_DEPRECATED) &&
1008 		    (dst2->aio_srcflag & AIO_SRCFLAG_DEPRECATED)) {
1009 			return(-1);
1010 		}
1011 		if ((dst1->aio_srcflag & AIO_SRCFLAG_DEPRECATED) &&
1012 		    !(dst2->aio_srcflag & AIO_SRCFLAG_DEPRECATED)) {
1013 			return(1);
1014 		}
1015 	}
1016 
1017 	/* Rule 4: Prefer home addresses. */
1018 	/* XXX: not implemented yet */
1019 
1020 	/* Rule 5: Prefer matching label. */
1021 #ifdef INET6
1022 	if (dst1->aio_srcpolicy && dst1->aio_dstpolicy &&
1023 	    dst1->aio_srcpolicy->pc_policy.label ==
1024 	    dst1->aio_dstpolicy->pc_policy.label &&
1025 	    (dst2->aio_srcpolicy == NULL || dst2->aio_dstpolicy == NULL ||
1026 	     dst2->aio_srcpolicy->pc_policy.label !=
1027 	     dst2->aio_dstpolicy->pc_policy.label)) {
1028 		return(-1);
1029 	}
1030 	if (dst2->aio_srcpolicy && dst2->aio_dstpolicy &&
1031 	    dst2->aio_srcpolicy->pc_policy.label ==
1032 	    dst2->aio_dstpolicy->pc_policy.label &&
1033 	    (dst1->aio_srcpolicy == NULL || dst1->aio_dstpolicy == NULL ||
1034 	     dst1->aio_srcpolicy->pc_policy.label !=
1035 	     dst1->aio_dstpolicy->pc_policy.label)) {
1036 		return(1);
1037 	}
1038 #endif
1039 
1040 	/* Rule 6: Prefer higher precedence. */
1041 #ifdef INET6
1042 	if (dst1->aio_dstpolicy &&
1043 	    (dst2->aio_dstpolicy == NULL ||
1044 	     dst1->aio_dstpolicy->pc_policy.preced >
1045 	     dst2->aio_dstpolicy->pc_policy.preced)) {
1046 		return(-1);
1047 	}
1048 	if (dst2->aio_dstpolicy &&
1049 	    (dst1->aio_dstpolicy == NULL ||
1050 	     dst2->aio_dstpolicy->pc_policy.preced >
1051 	     dst1->aio_dstpolicy->pc_policy.preced)) {
1052 		return(1);
1053 	}
1054 #endif
1055 
1056 	/* Rule 7: Prefer native transport. */
1057 	/* XXX: not implemented yet */
1058 
1059 	/* Rule 8: Prefer smaller scope. */
1060 	if (dst1->aio_dstscope >= 0 &&
1061 	    dst1->aio_dstscope < dst2->aio_dstscope) {
1062 		return(-1);
1063 	}
1064 	if (dst2->aio_dstscope >= 0 &&
1065 	    dst2->aio_dstscope < dst1->aio_dstscope) {
1066 		return(1);
1067 	}
1068 
1069 	/*
1070 	 * Rule 9: Use longest matching prefix.
1071 	 * We compare the match length in a same AF only.
1072 	 */
1073 	if (dst1->aio_ai->ai_addr->sa_family ==
1074 	    dst2->aio_ai->ai_addr->sa_family &&
1075 	    dst1->aio_ai->ai_addr->sa_family != AF_INET) {
1076 		if (dst1->aio_matchlen > dst2->aio_matchlen) {
1077 			return(-1);
1078 		}
1079 		if (dst1->aio_matchlen < dst2->aio_matchlen) {
1080 			return(1);
1081 		}
1082 	}
1083 
1084 	/* Rule 10: Otherwise, leave the order unchanged. */
1085 	return(-1);
1086 }
1087 
1088 /*
1089  * Copy from scope.c.
1090  * XXX: we should standardize the functions and link them as standard
1091  * library.
1092  */
1093 static int
1094 gai_addr2scopetype(struct sockaddr *sa)
1095 {
1096 #ifdef INET6
1097 	struct sockaddr_in6 *sa6;
1098 #endif
1099 	struct sockaddr_in *sa4;
1100 
1101 	switch(sa->sa_family) {
1102 #ifdef INET6
1103 	case AF_INET6:
1104 		sa6 = (struct sockaddr_in6 *)sa;
1105 		if (IN6_IS_ADDR_MULTICAST(&sa6->sin6_addr)) {
1106 			/* just use the scope field of the multicast address */
1107 			return(sa6->sin6_addr.s6_addr[2] & 0x0f);
1108 		}
1109 		/*
1110 		 * Unicast addresses: map scope type to corresponding scope
1111 		 * value defined for multcast addresses.
1112 		 * XXX: hardcoded scope type values are bad...
1113 		 */
1114 		if (IN6_IS_ADDR_LOOPBACK(&sa6->sin6_addr))
1115 			return(1); /* node local scope */
1116 		if (IN6_IS_ADDR_LINKLOCAL(&sa6->sin6_addr))
1117 			return(2); /* link-local scope */
1118 		if (IN6_IS_ADDR_SITELOCAL(&sa6->sin6_addr))
1119 			return(5); /* site-local scope */
1120 		return(14);	/* global scope */
1121 		break;
1122 #endif
1123 	case AF_INET:
1124 		/*
1125 		 * IPv4 pseudo scoping according to RFC 3484.
1126 		 */
1127 		sa4 = (struct sockaddr_in *)sa;
1128 		/* IPv4 autoconfiguration addresses have link-local scope. */
1129 		if (((u_char *)&sa4->sin_addr)[0] == 169 &&
1130 		    ((u_char *)&sa4->sin_addr)[1] == 254)
1131 			return(2);
1132 		/* Private addresses have site-local scope. */
1133 		if (((u_char *)&sa4->sin_addr)[0] == 10 ||
1134 		    (((u_char *)&sa4->sin_addr)[0] == 172 &&
1135 		     (((u_char *)&sa4->sin_addr)[1] & 0xf0) == 16) ||
1136 		    (((u_char *)&sa4->sin_addr)[0] == 192 &&
1137 		     ((u_char *)&sa4->sin_addr)[1] == 168))
1138 			return(14);	/* XXX: It should be 5 unless NAT */
1139 		/* Loopback addresses have link-local scope. */
1140 		if (((u_char *)&sa4->sin_addr)[0] == 127)
1141 			return(2);
1142 		return(14);
1143 		break;
1144 	default:
1145 		errno = EAFNOSUPPORT; /* is this a good error? */
1146 		return(-1);
1147 	}
1148 }
1149 
1150 /*
1151  * FQDN hostname, DNS lookup
1152  */
1153 static int
1154 explore_fqdn(const struct addrinfo *pai, const char *hostname,
1155     const char *servname, struct addrinfo **res, struct servent_data *svd)
1156 {
1157 	struct addrinfo *result;
1158 	struct addrinfo *cur;
1159 	int error = 0;
1160 	static const ns_dtab dtab[] = {
1161 		NS_FILES_CB(_files_getaddrinfo, NULL)
1162 		{ NSSRC_DNS, _dns_getaddrinfo, NULL },	/* force -DHESIOD */
1163 		NS_NIS_CB(_yp_getaddrinfo, NULL)
1164 		NS_NULL_CB
1165 	};
1166 
1167 	_DIAGASSERT(pai != NULL);
1168 	/* hostname may be NULL */
1169 	/* servname may be NULL */
1170 	_DIAGASSERT(res != NULL);
1171 
1172 	result = NULL;
1173 
1174 	/*
1175 	 * if the servname does not match socktype/protocol, ignore it.
1176 	 */
1177 	if (get_portmatch(pai, servname, svd) != 0)
1178 		return 0;
1179 
1180 	switch (nsdispatch(&result, dtab, NSDB_HOSTS, "getaddrinfo",
1181 	    default_dns_files, hostname, pai, servname)) {
1182 	case NS_TRYAGAIN:
1183 		error = EAI_AGAIN;
1184 		goto free;
1185 	case NS_UNAVAIL:
1186 		error = EAI_FAIL;
1187 		goto free;
1188 	case NS_NOTFOUND:
1189 		error = EAI_NONAME;
1190 		goto free;
1191 	case NS_SUCCESS:
1192 		error = 0;
1193 		for (cur = result; cur; cur = cur->ai_next) {
1194 			/* Check for already filled port. */
1195 			if (*getport(cur))
1196 				continue;
1197 			GET_PORT(cur, servname, svd);
1198 			/* canonname should be filled already */
1199 		}
1200 		break;
1201 	}
1202 
1203 	*res = result;
1204 
1205 	return 0;
1206 
1207 free:
1208 	if (result)
1209 		freeaddrinfo(result);
1210 	return error;
1211 }
1212 
1213 /*
1214  * hostname == NULL.
1215  * passive socket -> anyaddr (0.0.0.0 or ::)
1216  * non-passive socket -> localhost (127.0.0.1 or ::1)
1217  */
1218 static int
1219 explore_null(const struct addrinfo *pai, const char *servname,
1220     struct addrinfo **res, struct servent_data *svd)
1221 {
1222 	int s;
1223 	const struct afd *afd;
1224 	struct addrinfo *cur;
1225 	struct addrinfo sentinel;
1226 	int error;
1227 
1228 	_DIAGASSERT(pai != NULL);
1229 	/* servname may be NULL */
1230 	_DIAGASSERT(res != NULL);
1231 
1232 	*res = NULL;
1233 	sentinel.ai_next = NULL;
1234 	cur = &sentinel;
1235 
1236 	/*
1237 	 * filter out AFs that are not supported by the kernel
1238 	 * XXX errno?
1239 	 */
1240 	s = socket(pai->ai_family, SOCK_DGRAM, 0);
1241 	if (s < 0) {
1242 		if (errno != EMFILE)
1243 			return 0;
1244 	} else
1245 		close(s);
1246 
1247 	/*
1248 	 * if the servname does not match socktype/protocol, ignore it.
1249 	 */
1250 	if (get_portmatch(pai, servname, svd) != 0)
1251 		return 0;
1252 
1253 	afd = find_afd(pai->ai_family);
1254 	if (afd == NULL)
1255 		return 0;
1256 
1257 	if (pai->ai_flags & AI_PASSIVE) {
1258 		GET_AI(cur->ai_next, afd, afd->a_addrany);
1259 		/* xxx meaningless?
1260 		 * GET_CANONNAME(cur->ai_next, "anyaddr");
1261 		 */
1262 		GET_PORT(cur->ai_next, servname, svd);
1263 	} else {
1264 		GET_AI(cur->ai_next, afd, afd->a_loopback);
1265 		/* xxx meaningless?
1266 		 * GET_CANONNAME(cur->ai_next, "localhost");
1267 		 */
1268 		GET_PORT(cur->ai_next, servname, svd);
1269 	}
1270 	cur = cur->ai_next;
1271 
1272 	*res = sentinel.ai_next;
1273 	return 0;
1274 
1275 free:
1276 	if (sentinel.ai_next)
1277 		freeaddrinfo(sentinel.ai_next);
1278 	return error;
1279 }
1280 
1281 /*
1282  * numeric hostname
1283  */
1284 static int
1285 explore_numeric(const struct addrinfo *pai, const char *hostname,
1286     const char *servname, struct addrinfo **res, const char *canonname,
1287     struct servent_data *svd)
1288 {
1289 	const struct afd *afd;
1290 	struct addrinfo *cur;
1291 	struct addrinfo sentinel;
1292 	int error;
1293 	char pton[PTON_MAX];
1294 
1295 	_DIAGASSERT(pai != NULL);
1296 	/* hostname may be NULL */
1297 	/* servname may be NULL */
1298 	_DIAGASSERT(res != NULL);
1299 
1300 	*res = NULL;
1301 	sentinel.ai_next = NULL;
1302 	cur = &sentinel;
1303 
1304 	/*
1305 	 * if the servname does not match socktype/protocol, ignore it.
1306 	 */
1307 	if (get_portmatch(pai, servname, svd) != 0)
1308 		return 0;
1309 
1310 	afd = find_afd(pai->ai_family);
1311 	if (afd == NULL)
1312 		return 0;
1313 
1314 	switch (afd->a_af) {
1315 	case AF_INET:
1316 	       /*
1317 		* RFC3493 section 6.1, requires getaddrinfo() to accept
1318 		* AF_INET formats that are accepted by inet_addr(); here
1319 		* we use the equivalent inet_aton() function so we can
1320 		* check for errors. inet_pton() only accepts addresses
1321 		* in the dotted quad format and only in base 10, so we
1322 		* need to treat AF_INET specially.
1323 		*/
1324 		if (inet_aton(hostname, (struct in_addr *)pton) == 1) {
1325 			if (pai->ai_family == afd->a_af ||
1326 			    pai->ai_family == PF_UNSPEC /*?*/) {
1327 				GET_AI(cur->ai_next, afd, pton);
1328 				GET_PORT(cur->ai_next, servname, svd);
1329 				if ((pai->ai_flags & AI_CANONNAME)) {
1330 					/*
1331 					 * Set the numeric address itself as
1332 					 * the canonical name, based on a
1333 					 * clarification in rfc2553bis-03.
1334 					 */
1335 					GET_CANONNAME(cur->ai_next, canonname);
1336 				}
1337 				while (cur && cur->ai_next)
1338 					cur = cur->ai_next;
1339 			} else
1340 				ERR(EAI_FAMILY);	/*xxx*/
1341 		}
1342 		break;
1343 	default:
1344 		if (inet_pton(afd->a_af, hostname, pton) == 1) {
1345 			if (pai->ai_family == afd->a_af ||
1346 			    pai->ai_family == PF_UNSPEC /*?*/) {
1347 				GET_AI(cur->ai_next, afd, pton);
1348 				GET_PORT(cur->ai_next, servname, svd);
1349 				if ((pai->ai_flags & AI_CANONNAME)) {
1350 					/*
1351 					 * Set the numeric address itself as
1352 					 * the canonical name, based on a
1353 					 * clarification in rfc2553bis-03.
1354 					 */
1355 					GET_CANONNAME(cur->ai_next, canonname);
1356 				}
1357 				while (cur->ai_next)
1358 					cur = cur->ai_next;
1359 			} else
1360 				ERR(EAI_FAMILY);	/*xxx*/
1361 		}
1362 		break;
1363 	}
1364 
1365 	*res = sentinel.ai_next;
1366 	return 0;
1367 
1368 free:
1369 bad:
1370 	if (sentinel.ai_next)
1371 		freeaddrinfo(sentinel.ai_next);
1372 	return error;
1373 }
1374 
1375 /*
1376  * numeric hostname with scope
1377  */
1378 static int
1379 explore_numeric_scope(const struct addrinfo *pai, const char *hostname,
1380     const char *servname, struct addrinfo **res, struct servent_data *svd)
1381 {
1382 #if !defined(SCOPE_DELIMITER) || !defined(INET6)
1383 	return explore_numeric(pai, hostname, servname, res, hostname, svd);
1384 #else
1385 	const struct afd *afd;
1386 	struct addrinfo *cur;
1387 	int error;
1388 	char *cp, *hostname2 = NULL, *scope, *addr;
1389 	struct sockaddr_in6 *sin6;
1390 
1391 	_DIAGASSERT(pai != NULL);
1392 	/* hostname may be NULL */
1393 	/* servname may be NULL */
1394 	_DIAGASSERT(res != NULL);
1395 
1396 	/*
1397 	 * if the servname does not match socktype/protocol, ignore it.
1398 	 */
1399 	if (get_portmatch(pai, servname, svd) != 0)
1400 		return 0;
1401 
1402 	afd = find_afd(pai->ai_family);
1403 	if (afd == NULL)
1404 		return 0;
1405 
1406 	if (!afd->a_scoped)
1407 		return explore_numeric(pai, hostname, servname, res, hostname,
1408 		    svd);
1409 
1410 	cp = strchr(hostname, SCOPE_DELIMITER);
1411 	if (cp == NULL)
1412 		return explore_numeric(pai, hostname, servname, res, hostname,
1413 		    svd);
1414 
1415 	/*
1416 	 * Handle special case of <scoped_address><delimiter><scope id>
1417 	 */
1418 	hostname2 = strdup(hostname);
1419 	if (hostname2 == NULL)
1420 		return EAI_MEMORY;
1421 	/* terminate at the delimiter */
1422 	hostname2[cp - hostname] = '\0';
1423 	addr = hostname2;
1424 	scope = cp + 1;
1425 
1426 	error = explore_numeric(pai, addr, servname, res, hostname, svd);
1427 	if (error == 0) {
1428 		u_int32_t scopeid;
1429 
1430 		for (cur = *res; cur; cur = cur->ai_next) {
1431 			if (cur->ai_family != AF_INET6)
1432 				continue;
1433 			sin6 = (struct sockaddr_in6 *)(void *)cur->ai_addr;
1434 			if (ip6_str2scopeid(scope, sin6, &scopeid) == -1) {
1435 				free(hostname2);
1436 				return(EAI_NODATA); /* XXX: is return OK? */
1437 			}
1438 			sin6->sin6_scope_id = scopeid;
1439 		}
1440 	}
1441 
1442 	free(hostname2);
1443 
1444 	return error;
1445 #endif
1446 }
1447 
1448 static int
1449 get_canonname(const struct addrinfo *pai, struct addrinfo *ai, const char *str)
1450 {
1451 
1452 	_DIAGASSERT(pai != NULL);
1453 	_DIAGASSERT(ai != NULL);
1454 	_DIAGASSERT(str != NULL);
1455 
1456 	if ((pai->ai_flags & AI_CANONNAME) != 0) {
1457 		ai->ai_canonname = strdup(str);
1458 		if (ai->ai_canonname == NULL)
1459 			return EAI_MEMORY;
1460 	}
1461 	return 0;
1462 }
1463 
1464 struct addrinfo *
1465 allocaddrinfo(socklen_t addrlen)
1466 {
1467 	struct addrinfo *ai;
1468 
1469 	ai = calloc(sizeof(struct addrinfo) + addrlen, 1);
1470 	if (ai) {
1471 		ai->ai_addr = (void *)(ai+1);
1472 		ai->ai_addrlen = ai->ai_addr->sa_len = addrlen;
1473 	}
1474 
1475 	return ai;
1476 }
1477 
1478 static struct addrinfo *
1479 get_ai(const struct addrinfo *pai, const struct afd *afd, const char *addr)
1480 {
1481 	char *p;
1482 	struct addrinfo *ai;
1483 	struct sockaddr *save;
1484 
1485 	_DIAGASSERT(pai != NULL);
1486 	_DIAGASSERT(afd != NULL);
1487 	_DIAGASSERT(addr != NULL);
1488 
1489 	ai = allocaddrinfo((socklen_t)afd->a_socklen);
1490 	if (ai == NULL)
1491 		return NULL;
1492 
1493 	save = ai->ai_addr;
1494 	memcpy(ai, pai, sizeof(struct addrinfo));
1495 
1496 	/* since we just overwrote all of ai, we have
1497 	   to restore ai_addr and ai_addrlen */
1498 	ai->ai_addr = save;
1499 	ai->ai_addrlen = (socklen_t)afd->a_socklen;
1500 
1501 	ai->ai_addr->sa_family = ai->ai_family = afd->a_af;
1502 	p = (char *)(void *)(ai->ai_addr);
1503 	memcpy(p + afd->a_off, addr, (size_t)afd->a_addrlen);
1504 	return ai;
1505 }
1506 
1507 static int
1508 get_portmatch(const struct addrinfo *ai, const char *servname,
1509     struct servent_data *svd)
1510 {
1511 
1512 	_DIAGASSERT(ai != NULL);
1513 	/* servname may be NULL */
1514 
1515 	return get_port(ai, servname, 1, svd);
1516 }
1517 
1518 static int
1519 get_port(const struct addrinfo *ai, const char *servname, int matchonly,
1520     struct servent_data *svd)
1521 {
1522 	const char *proto;
1523 	struct servent *sp;
1524 	int port;
1525 	int allownumeric;
1526 
1527 	_DIAGASSERT(ai != NULL);
1528 	/* servname may be NULL */
1529 
1530 	if (servname == NULL)
1531 		return 0;
1532 	switch (ai->ai_family) {
1533 	case AF_INET:
1534 #ifdef AF_INET6
1535 	case AF_INET6:
1536 #endif
1537 		break;
1538 	default:
1539 		return 0;
1540 	}
1541 
1542 	switch (ai->ai_socktype) {
1543 	case SOCK_RAW:
1544 		return EAI_SERVICE;
1545 	case SOCK_DGRAM:
1546 	case SOCK_STREAM:
1547 		allownumeric = 1;
1548 		break;
1549 	case ANY:
1550 		/*
1551 		 * This was 0.	It is now 1 so that queries specifying
1552 		 * a NULL hint, or hint without socktype (but, hopefully,
1553 		 * with protocol) and numeric address actually work.
1554 		 */
1555 		allownumeric = 1;
1556 		break;
1557 	default:
1558 		return EAI_SOCKTYPE;
1559 	}
1560 
1561 	port = str2number(servname);
1562 	if (port >= 0) {
1563 		if (!allownumeric)
1564 			return EAI_SERVICE;
1565 		if (port < 0 || port > 65535)
1566 			return EAI_SERVICE;
1567 		port = htons(port);
1568 	} else {
1569 		struct servent sv;
1570 		if (ai->ai_flags & AI_NUMERICSERV)
1571 			return EAI_NONAME;
1572 
1573 		switch (ai->ai_socktype) {
1574 		case SOCK_DGRAM:
1575 			proto = "udp";
1576 			break;
1577 		case SOCK_STREAM:
1578 			proto = "tcp";
1579 			break;
1580 		default:
1581 			proto = NULL;
1582 			break;
1583 		}
1584 
1585 		sp = getservbyname_r(servname, proto, &sv, svd);
1586 		if (sp == NULL)
1587 			return EAI_SERVICE;
1588 		port = sp->s_port;
1589 	}
1590 
1591 	if (!matchonly)
1592 		*getport(__UNCONST(ai)) = port;
1593 	return 0;
1594 }
1595 
1596 static const struct afd *
1597 find_afd(int af)
1598 {
1599 	const struct afd *afd;
1600 
1601 	if (af == PF_UNSPEC)
1602 		return NULL;
1603 	for (afd = afdl; afd->a_af; afd++) {
1604 		if (afd->a_af == af)
1605 			return afd;
1606 	}
1607 	return NULL;
1608 }
1609 
1610 /*
1611  * AI_ADDRCONFIG check: Build a mask containing a bit set for each address
1612  * family configured in the system.
1613  *
1614  */
1615 static int
1616 addrconfig(uint64_t *mask)
1617 {
1618 	struct ifaddrs *ifaddrs, *ifa;
1619 
1620 	if (getifaddrs(&ifaddrs) == -1)
1621 		return -1;
1622 
1623 	*mask = 0;
1624 	for (ifa = ifaddrs; ifa != NULL; ifa = ifa->ifa_next)
1625 		if (ifa->ifa_addr && (ifa->ifa_flags & IFF_UP)) {
1626 			_DIAGASSERT(ifa->ifa_addr->sa_family < 64);
1627 			*mask |= (uint64_t)1 << ifa->ifa_addr->sa_family;
1628 		}
1629 
1630 	freeifaddrs(ifaddrs);
1631 	return 0;
1632 }
1633 
1634 #ifdef INET6
1635 /* convert a string to a scope identifier. XXX: IPv6 specific */
1636 static int
1637 ip6_str2scopeid(char *scope, struct sockaddr_in6 *sin6, u_int32_t *scopeid)
1638 {
1639 	u_long lscopeid;
1640 	struct in6_addr *a6;
1641 	char *ep;
1642 
1643 	_DIAGASSERT(scope != NULL);
1644 	_DIAGASSERT(sin6 != NULL);
1645 	_DIAGASSERT(scopeid != NULL);
1646 
1647 	a6 = &sin6->sin6_addr;
1648 
1649 	/* empty scopeid portion is invalid */
1650 	if (*scope == '\0')
1651 		return -1;
1652 
1653 	if (IN6_IS_ADDR_LINKLOCAL(a6) || IN6_IS_ADDR_MC_LINKLOCAL(a6)) {
1654 		/*
1655 		 * We currently assume a one-to-one mapping between links
1656 		 * and interfaces, so we simply use interface indices for
1657 		 * like-local scopes.
1658 		 */
1659 		*scopeid = if_nametoindex(scope);
1660 		if (*scopeid == 0)
1661 			goto trynumeric;
1662 		return 0;
1663 	}
1664 
1665 	/* still unclear about literal, allow numeric only - placeholder */
1666 	if (IN6_IS_ADDR_SITELOCAL(a6) || IN6_IS_ADDR_MC_SITELOCAL(a6))
1667 		goto trynumeric;
1668 	if (IN6_IS_ADDR_MC_ORGLOCAL(a6))
1669 		goto trynumeric;
1670 	else
1671 		goto trynumeric;	/* global */
1672 
1673 	/* try to convert to a numeric id as a last resort */
1674   trynumeric:
1675 	errno = 0;
1676 	lscopeid = strtoul(scope, &ep, 10);
1677 	*scopeid = (u_int32_t)(lscopeid & 0xffffffffUL);
1678 	if (errno == 0 && ep && *ep == '\0' && *scopeid == lscopeid)
1679 		return 0;
1680 	else
1681 		return -1;
1682 }
1683 #endif
1684 
1685 /* code duplicate with gethnamaddr.c */
1686 
1687 static const char AskedForGot[] =
1688 	"gethostby*.getanswer: asked for \"%s\", got \"%s\"";
1689 
1690 #define maybe_ok(res, nm, ok) (((res)->options & RES_NOCHECKNAME) != 0U || \
1691                                (ok)(nm) != 0)
1692 static struct addrinfo *
1693 getanswer(res_state res, const querybuf *answer, int anslen, const char *qname,
1694     int qtype, const struct addrinfo *pai)
1695 {
1696 	struct addrinfo sentinel, *cur;
1697 	struct addrinfo ai, *aip;
1698 	const struct afd *afd;
1699 	char *canonname;
1700 	const HEADER *hp;
1701 	const u_char *cp;
1702 	int n;
1703 	const u_char *eom;
1704 	char *bp, *ep;
1705 	int type, class, ancount, qdcount;
1706 	int haveanswer, had_error;
1707 	char tbuf[MAXDNAME];
1708 	int (*name_ok) (const char *);
1709 	char hostbuf[8*1024];
1710 	int port, pri, weight;
1711 	struct srvinfo *srvlist, *srv, *csrv;
1712 
1713 	_DIAGASSERT(answer != NULL);
1714 	_DIAGASSERT(qname != NULL);
1715 	_DIAGASSERT(pai != NULL);
1716 	_DIAGASSERT(res != NULL);
1717 
1718 	memset(&sentinel, 0, sizeof(sentinel));
1719 	cur = &sentinel;
1720 
1721 	canonname = NULL;
1722 	eom = answer->buf + anslen;
1723 	switch (qtype) {
1724 	case T_A:
1725 	case T_AAAA:
1726 	case T_ANY:	/*use T_ANY only for T_A/T_AAAA lookup*/
1727 		name_ok = res_hnok;
1728 		break;
1729 	case T_SRV:
1730 		name_ok = gai_srvok;
1731 		break;
1732 	default:
1733 		return NULL;	/* XXX should be abort(); */
1734 	}
1735 	/*
1736 	 * find first satisfactory answer
1737 	 */
1738 	hp = &answer->hdr;
1739 	ancount = ntohs(hp->ancount);
1740 	qdcount = ntohs(hp->qdcount);
1741 	bp = hostbuf;
1742 	ep = hostbuf + sizeof hostbuf;
1743 	cp = answer->buf + HFIXEDSZ;
1744 	if (qdcount != 1) {
1745 		h_errno = NO_RECOVERY;
1746 		return (NULL);
1747 	}
1748 	n = dn_expand(answer->buf, eom, cp, bp, (int)(ep - bp));
1749 	if ((n < 0) || !maybe_ok(res, bp, name_ok)) {
1750 		h_errno = NO_RECOVERY;
1751 		return (NULL);
1752 	}
1753 	cp += n + QFIXEDSZ;
1754 	if (qtype == T_A || qtype == T_AAAA || qtype == T_ANY) {
1755 		/* res_send() has already verified that the query name is the
1756 		 * same as the one we sent; this just gets the expanded name
1757 		 * (i.e., with the succeeding search-domain tacked on).
1758 		 */
1759 		n = (int)strlen(bp) + 1;		/* for the \0 */
1760 		if (n >= MAXHOSTNAMELEN) {
1761 			h_errno = NO_RECOVERY;
1762 			return (NULL);
1763 		}
1764 		canonname = bp;
1765 		bp += n;
1766 		/* The qname can be abbreviated, but h_name is now absolute. */
1767 		qname = canonname;
1768 	}
1769 	haveanswer = 0;
1770 	had_error = 0;
1771 	srvlist = NULL;
1772 	while (ancount-- > 0 && cp < eom && !had_error) {
1773 		n = dn_expand(answer->buf, eom, cp, bp, (int)(ep - bp));
1774 		if ((n < 0) || !maybe_ok(res, bp, name_ok)) {
1775 			had_error++;
1776 			continue;
1777 		}
1778 		cp += n;			/* name */
1779 		type = _getshort(cp);
1780 		cp += INT16SZ;			/* type */
1781 		class = _getshort(cp);
1782 		cp += INT16SZ + INT32SZ;	/* class, TTL */
1783 		n = _getshort(cp);
1784 		cp += INT16SZ;			/* len */
1785 		if (class != C_IN) {
1786 			/* XXX - debug? syslog? */
1787 			cp += n;
1788 			continue;		/* XXX - had_error++ ? */
1789 		}
1790 		if ((qtype == T_A || qtype == T_AAAA || qtype == T_ANY) &&
1791 		    type == T_CNAME) {
1792 			n = dn_expand(answer->buf, eom, cp, tbuf, (int)sizeof tbuf);
1793 			if ((n < 0) || !maybe_ok(res, tbuf, name_ok)) {
1794 				had_error++;
1795 				continue;
1796 			}
1797 			cp += n;
1798 			/* Get canonical name. */
1799 			n = (int)strlen(tbuf) + 1;	/* for the \0 */
1800 			if (n > ep - bp || n >= MAXHOSTNAMELEN) {
1801 				had_error++;
1802 				continue;
1803 			}
1804 			strlcpy(bp, tbuf, (size_t)(ep - bp));
1805 			canonname = bp;
1806 			bp += n;
1807 			continue;
1808 		}
1809 		if (qtype == T_ANY) {
1810 			if (!(type == T_A || type == T_AAAA)) {
1811 				cp += n;
1812 				continue;
1813 			}
1814 		} else if (type != qtype) {
1815 			if (type != T_KEY && type != T_SIG) {
1816 				struct syslog_data sd = SYSLOG_DATA_INIT;
1817 				syslog_r(LOG_NOTICE|LOG_AUTH, &sd,
1818 	       "gethostby*.getanswer: asked for \"%s %s %s\", got type \"%s\"",
1819 				       qname, p_class(C_IN), p_type(qtype),
1820 				       p_type(type));
1821 			}
1822 			cp += n;
1823 			continue;		/* XXX - had_error++ ? */
1824 		}
1825 		switch (type) {
1826 		case T_A:
1827 		case T_AAAA:
1828 			if (strcasecmp(canonname, bp) != 0) {
1829 				struct syslog_data sd = SYSLOG_DATA_INIT;
1830 				syslog_r(LOG_NOTICE|LOG_AUTH, &sd,
1831 				       AskedForGot, canonname, bp);
1832 				cp += n;
1833 				continue;	/* XXX - had_error++ ? */
1834 			}
1835 			if (type == T_A && n != INADDRSZ) {
1836 				cp += n;
1837 				continue;
1838 			}
1839 			if (type == T_AAAA && n != IN6ADDRSZ) {
1840 				cp += n;
1841 				continue;
1842 			}
1843 			if (type == T_AAAA) {
1844 				struct in6_addr in6;
1845 				memcpy(&in6, cp, IN6ADDRSZ);
1846 				if (IN6_IS_ADDR_V4MAPPED(&in6)) {
1847 					cp += n;
1848 					continue;
1849 				}
1850 			}
1851 			if (!haveanswer) {
1852 				int nn;
1853 
1854 				canonname = bp;
1855 				nn = (int)strlen(bp) + 1;	/* for the \0 */
1856 				bp += nn;
1857 			}
1858 
1859 			/* don't overwrite pai */
1860 			ai = *pai;
1861 			ai.ai_family = (type == T_A) ? AF_INET : AF_INET6;
1862 			afd = find_afd(ai.ai_family);
1863 			if (afd == NULL) {
1864 				cp += n;
1865 				continue;
1866 			}
1867 			cur->ai_next = get_ai(&ai, afd, (const char *)cp);
1868 			if (cur->ai_next == NULL)
1869 				had_error++;
1870 			while (cur && cur->ai_next)
1871 				cur = cur->ai_next;
1872 			cp += n;
1873 			break;
1874 		case T_SRV:
1875 			/* Add to SRV list. Insertion sort on priority. */
1876 			pri = _getshort(cp);
1877 			cp += INT16SZ;
1878 			weight = _getshort(cp);
1879 			cp += INT16SZ;
1880 			port = _getshort(cp);
1881 			cp += INT16SZ;
1882 			n = dn_expand(answer->buf, eom, cp, tbuf,
1883 			    (int)sizeof(tbuf));
1884 			if ((n < 0) || !maybe_ok(res, tbuf, res_hnok)) {
1885 				had_error++;
1886 				continue;
1887 			}
1888 			cp += n;
1889 			if (strlen(tbuf) + 1 >= MAXDNAME) {
1890 				had_error++;
1891 				continue;
1892 			}
1893 			srv = malloc(sizeof(*srv));
1894 			if (!srv) {
1895 				had_error++;
1896 				continue;
1897 			}
1898 			strlcpy(srv->name, tbuf, sizeof(srv->name));
1899 			srv->pri = pri;
1900 			srv->weight = weight;
1901 			srv->port = port;
1902 			/* Weight 0 is sorted before other weights. */
1903 			if (!srvlist
1904 			    || srv->pri < srvlist->pri
1905 			    || (srv->pri == srvlist->pri &&
1906 			    (!srv->weight || srvlist->weight))) {
1907 				srv->next = srvlist;
1908 				srvlist = srv;
1909 			} else {
1910 				for (csrv = srvlist;
1911 				    csrv->next && csrv->next->pri <= srv->pri;
1912 				    csrv = csrv->next) {
1913 					if (csrv->next->pri == srv->pri
1914 					    && (!srv->weight ||
1915 					    csrv->next->weight))
1916 						break;
1917 				}
1918 				srv->next = csrv->next;
1919 				csrv->next = srv;
1920 			}
1921 			continue; /* Don't add to haveanswer yet. */
1922 		default:
1923 			abort();
1924 		}
1925 		if (!had_error)
1926 			haveanswer++;
1927 	}
1928 
1929 	if (srvlist) {
1930 		/*
1931 		 * Check for explicit rejection.
1932 		 */
1933 		if (!srvlist->next && !srvlist->name[0]) {
1934 			free(srvlist);
1935 			h_errno = HOST_NOT_FOUND;
1936 			return NULL;
1937 		}
1938 
1939 		while (srvlist) {
1940 			struct res_target q, q2;
1941 
1942 			srv = srvlist;
1943 			srvlist = srvlist->next;
1944 
1945 			/*
1946 			 * Since res_* doesn't give the additional
1947 			 * section, we always look up.
1948 			 */
1949 			memset(&q, 0, sizeof(q));
1950 			memset(&q2, 0, sizeof(q2));
1951 
1952 			q.name = srv->name;
1953 			q.qclass = C_IN;
1954 			q.qtype = T_AAAA;
1955 			q.next = &q2;
1956 			q2.name = srv->name;
1957 			q2.qclass = C_IN;
1958 			q2.qtype = T_A;
1959 
1960 			aip = _dns_query(&q, pai, res, 0);
1961 
1962 			if (aip != NULL) {
1963 				cur->ai_next = aip;
1964 				while (cur && cur->ai_next) {
1965 					cur = cur->ai_next;
1966 					*getport(cur) = htons(srv->port);
1967 					haveanswer++;
1968 				}
1969 			}
1970 			free(srv);
1971 		}
1972 	}
1973 	if (haveanswer) {
1974 		if (!sentinel.ai_next->ai_canonname)
1975 		       (void)get_canonname(pai, sentinel.ai_next,
1976 			   canonname ? canonname : qname);
1977 		h_errno = NETDB_SUCCESS;
1978 		return sentinel.ai_next;
1979 	}
1980 
1981 	/* We could have walked a CNAME chain, */
1982 	/* but the ultimate target may not have what we looked for */
1983 	h_errno = ntohs(hp->ancount) > 0? NO_DATA : NO_RECOVERY;
1984 	return NULL;
1985 }
1986 
1987 #define SORTEDADDR(p)	(((struct sockaddr_in *)(void *)(p->ai_next->ai_addr))->sin_addr.s_addr)
1988 #define SORTMATCH(p, s) ((SORTEDADDR(p) & (s).mask) == (s).addr.s_addr)
1989 
1990 static void
1991 aisort(struct addrinfo *s, res_state res)
1992 {
1993 	struct addrinfo head, *t, *p;
1994 	int i;
1995 
1996 	head.ai_next = NULL;
1997 	t = &head;
1998 
1999 	for (i = 0; i < res->nsort; i++) {
2000 		p = s;
2001 		while (p->ai_next) {
2002 			if ((p->ai_next->ai_family != AF_INET)
2003 			|| SORTMATCH(p, res->sort_list[i])) {
2004 				t->ai_next = p->ai_next;
2005 				t = t->ai_next;
2006 				p->ai_next = p->ai_next->ai_next;
2007 			} else {
2008 				p = p->ai_next;
2009 			}
2010 		}
2011 	}
2012 
2013 	/* add rest of list and reset s to the new list*/
2014 	t->ai_next = s->ai_next;
2015 	s->ai_next = head.ai_next;
2016 }
2017 
2018 static struct addrinfo *
2019 _dns_query(struct res_target *q, const struct addrinfo *pai,
2020     res_state res, int dosearch)
2021 {
2022 	struct res_target *q2 = q->next;
2023  	querybuf *buf, *buf2;
2024 	struct addrinfo sentinel, *cur, *ai;
2025 
2026 #ifdef DNS_DEBUG
2027 	struct res_target *iter;
2028 	for (iter = q; iter; iter = iter->next)
2029 		printf("Query type %d for %s\n", iter->qtype, iter->name);
2030 #endif
2031 
2032  	buf = malloc(sizeof(*buf));
2033  	if (buf == NULL) {
2034  		h_errno = NETDB_INTERNAL;
2035 		return NULL;
2036  	}
2037  	buf2 = malloc(sizeof(*buf2));
2038  	if (buf2 == NULL) {
2039  		free(buf);
2040  		h_errno = NETDB_INTERNAL;
2041 		return NULL;
2042 	}
2043 
2044 	memset(&sentinel, 0, sizeof(sentinel));
2045 	cur = &sentinel;
2046 
2047 	q->answer = buf->buf;
2048 	q->anslen = sizeof(buf->buf);
2049 	if (q2) {
2050 		q2->answer = buf2->buf;
2051 		q2->anslen = sizeof(buf2->buf);
2052 	}
2053 
2054 	if (dosearch) {
2055 		if (res_searchN(q->name, q, res) < 0)
2056 			goto out;
2057 	} else {
2058 		if (res_queryN(q->name, q, res) < 0)
2059 			goto out;
2060 	}
2061 
2062 	ai = getanswer(res, buf, q->n, q->name, q->qtype, pai);
2063 	if (ai) {
2064 		cur->ai_next = ai;
2065 		while (cur && cur->ai_next)
2066 			cur = cur->ai_next;
2067 	}
2068 	if (q2) {
2069 		ai = getanswer(res, buf2, q2->n, q2->name, q2->qtype, pai);
2070 		if (ai)
2071 			cur->ai_next = ai;
2072  	}
2073 	free(buf);
2074 	free(buf2);
2075 	return sentinel.ai_next;
2076 out:
2077 	free(buf);
2078 	free(buf2);
2079 	return NULL;
2080 }
2081 
2082 /*ARGSUSED*/
2083 static struct addrinfo *
2084 _dns_srv_lookup(const char *name, const char *servname,
2085     const struct addrinfo *pai)
2086 {
2087 	static const char * const srvprotos[] = { "tcp", "udp" };
2088 	static const int srvnottype[] = { SOCK_DGRAM, SOCK_STREAM };
2089 	static const int nsrvprotos = 2;
2090 	struct addrinfo sentinel, *cur, *ai;
2091 	struct servent *serv, sv;
2092 	struct servent_data svd;
2093 	struct res_target q;
2094 	res_state res;
2095 	char *tname;
2096 	int i;
2097 
2098 	res = __res_get_state();
2099 	if (res == NULL)
2100 		return NULL;
2101 
2102 	memset(&svd, 0, sizeof(svd));
2103 	memset(&sentinel, 0, sizeof(sentinel));
2104 	cur = &sentinel;
2105 
2106 	/*
2107 	 * Iterate over supported SRV protocols.
2108 	 * (currently UDP and TCP only)
2109 	 */
2110 	for (i = 0; i < nsrvprotos; i++) {
2111 		/*
2112 		 * Check that the caller didn't specify a hint
2113 		 * which precludes this protocol.
2114 		 */
2115 		if (pai->ai_socktype == srvnottype[i])
2116 			continue;
2117 		/*
2118 		 * If the caller specified a port,
2119 		 * then lookup the database for the
2120 		 * official service name.
2121 		 */
2122 		serv = getservbyname_r(servname, srvprotos[i], &sv, &svd);
2123 		if (serv == NULL)
2124 			continue;
2125 
2126 		/*
2127 		 * Construct service DNS name.
2128 		 */
2129 		if (asprintf(&tname, "_%s._%s.%s", serv->s_name, serv->s_proto,
2130 		    name) < 0)
2131 			continue;
2132 
2133 		memset(&q, 0, sizeof(q));
2134 		q.name = tname;
2135 		q.qclass = C_IN;
2136 		q.qtype = T_SRV;
2137 
2138 		/*
2139 		 * Do SRV query.
2140 		 */
2141 		ai = _dns_query(&q, pai, res, 1);
2142 		if (ai) {
2143 			cur->ai_next = ai;
2144 			while (cur && cur->ai_next)
2145 				cur = cur->ai_next;
2146 		}
2147 		free(tname);
2148 	}
2149 
2150 	if (res->nsort)
2151 		aisort(&sentinel, res);
2152 
2153 	__res_put_state(res);
2154 
2155 	return sentinel.ai_next;
2156 }
2157 
2158 /*ARGSUSED*/
2159 static struct addrinfo *
2160 _dns_host_lookup(const char *name, const struct addrinfo *pai)
2161 {
2162 	struct res_target q, q2;
2163 	struct addrinfo sentinel, *ai;
2164 	res_state res;
2165 
2166 	res = __res_get_state();
2167 	if (res == NULL)
2168 		return NULL;
2169 
2170 	memset(&q, 0, sizeof(q2));
2171 	memset(&q2, 0, sizeof(q2));
2172 
2173 	switch (pai->ai_family) {
2174 	case AF_UNSPEC:
2175 		/* prefer IPv6 */
2176 		q.name = name;
2177 		q.qclass = C_IN;
2178 		q.qtype = T_AAAA;
2179 		q.next = &q2;
2180 		q2.name = name;
2181 		q2.qclass = C_IN;
2182 		q2.qtype = T_A;
2183 		break;
2184 	case AF_INET:
2185 		q.name = name;
2186 		q.qclass = C_IN;
2187 		q.qtype = T_A;
2188 		break;
2189 	case AF_INET6:
2190 		q.name = name;
2191 		q.qclass = C_IN;
2192 		q.qtype = T_AAAA;
2193 		break;
2194 	default:
2195 		__res_put_state(res);
2196 		h_errno = NETDB_INTERNAL;
2197 		return NULL;
2198 	}
2199 
2200 	ai = _dns_query(&q, pai, res, 1);
2201 
2202 	memset(&sentinel, 0, sizeof(sentinel));
2203 	sentinel.ai_next = ai;
2204 
2205 	if (ai != NULL && res->nsort)
2206 		aisort(&sentinel, res);
2207 
2208 	__res_put_state(res);
2209 
2210 	return sentinel.ai_next;
2211 }
2212 
2213 /*ARGSUSED*/
2214 static int
2215 _dns_getaddrinfo(void *rv, void *cb_data, va_list ap)
2216 {
2217 	struct addrinfo *ai = NULL;
2218 	const char *name, *servname;
2219 	const struct addrinfo *pai;
2220 
2221 	name = va_arg(ap, char *);
2222 	pai = va_arg(ap, const struct addrinfo *);
2223 	servname = va_arg(ap, char *);
2224 
2225 	/*
2226 	 * Try doing SRV lookup on service first.
2227 	 */
2228 	if (servname
2229 #ifdef AI_SRV
2230 	    && (pai->ai_flags & AI_SRV)
2231 #endif
2232 	    && !(pai->ai_flags & AI_NUMERICSERV)
2233 	    && str2number(servname) == -1) {
2234 
2235 #ifdef DNS_DEBUG
2236 		printf("%s: try SRV lookup\n", __func__);
2237 #endif
2238 		ai = _dns_srv_lookup(name, servname, pai);
2239 	}
2240 
2241 	/*
2242 	 * Do lookup on name.
2243 	 */
2244 	if (ai == NULL) {
2245 
2246 #ifdef DNS_DEBUG
2247 		printf("%s: try HOST lookup\n", __func__);
2248 #endif
2249 		ai = _dns_host_lookup(name, pai);
2250 
2251 		if (ai == NULL) {
2252 			switch (h_errno) {
2253 			case HOST_NOT_FOUND:
2254 			case NO_DATA:	// XXX: Perhaps we could differentiate
2255 					// So that we could return EAI_NODATA?
2256 				return NS_NOTFOUND;
2257 			case TRY_AGAIN:
2258 				return NS_TRYAGAIN;
2259 			default:
2260 				return NS_UNAVAIL;
2261 			}
2262 		}
2263 	}
2264 
2265 	*((struct addrinfo **)rv) = ai;
2266 	return NS_SUCCESS;
2267 }
2268 
2269 static void
2270 _sethtent(FILE **hostf)
2271 {
2272 
2273 	if (!*hostf)
2274 		*hostf = fopen(_PATH_HOSTS, "re");
2275 	else
2276 		rewind(*hostf);
2277 }
2278 
2279 static void
2280 _endhtent(FILE **hostf)
2281 {
2282 
2283 	if (*hostf) {
2284 		(void) fclose(*hostf);
2285 		*hostf = NULL;
2286 	}
2287 }
2288 
2289 static struct addrinfo *
2290 _gethtent(FILE **hostf, const char *name, const struct addrinfo *pai)
2291 {
2292 	char *p;
2293 	char *cp, *tname, *cname;
2294 	struct addrinfo hints, *res0, *res;
2295 	int error;
2296 	const char *addr;
2297 	char hostbuf[8*1024];
2298 
2299 	_DIAGASSERT(name != NULL);
2300 	_DIAGASSERT(pai != NULL);
2301 
2302 	if (!*hostf && !(*hostf = fopen(_PATH_HOSTS, "re")))
2303 		return (NULL);
2304  again:
2305 	if (!(p = fgets(hostbuf, (int)sizeof hostbuf, *hostf)))
2306 		return (NULL);
2307 	if (*p == '#')
2308 		goto again;
2309 	if (!(cp = strpbrk(p, "#\n")))
2310 		goto again;
2311 	*cp = '\0';
2312 	if (!(cp = strpbrk(p, " \t")))
2313 		goto again;
2314 	*cp++ = '\0';
2315 	addr = p;
2316 	/* if this is not something we're looking for, skip it. */
2317 	cname = NULL;
2318 	while (cp && *cp) {
2319 		if (*cp == ' ' || *cp == '\t') {
2320 			cp++;
2321 			continue;
2322 		}
2323 		if (!cname)
2324 			cname = cp;
2325 		tname = cp;
2326 		if ((cp = strpbrk(cp, " \t")) != NULL)
2327 			*cp++ = '\0';
2328 		if (strcasecmp(name, tname) == 0)
2329 			goto found;
2330 	}
2331 	goto again;
2332 
2333 found:
2334 	hints = *pai;
2335 	hints.ai_flags = AI_NUMERICHOST;
2336 	error = getaddrinfo(addr, NULL, &hints, &res0);
2337 	if (error)
2338 		goto again;
2339 	for (res = res0; res; res = res->ai_next) {
2340 		/* cover it up */
2341 		res->ai_flags = pai->ai_flags;
2342 
2343 		if (pai->ai_flags & AI_CANONNAME) {
2344 			if (get_canonname(pai, res, cname) != 0) {
2345 				freeaddrinfo(res0);
2346 				goto again;
2347 			}
2348 		}
2349 	}
2350 	return res0;
2351 }
2352 
2353 /*ARGSUSED*/
2354 static int
2355 _files_getaddrinfo(void *rv, void *cb_data, va_list ap)
2356 {
2357 	const char *name;
2358 	const struct addrinfo *pai;
2359 	struct addrinfo sentinel, *cur;
2360 	struct addrinfo *p;
2361 #ifndef _REENTRANT
2362 	static
2363 #endif
2364 	FILE *hostf = NULL;
2365 
2366 	name = va_arg(ap, char *);
2367 	pai = va_arg(ap, const struct addrinfo *);
2368 
2369 	memset(&sentinel, 0, sizeof(sentinel));
2370 	cur = &sentinel;
2371 
2372 	_sethtent(&hostf);
2373 	while ((p = _gethtent(&hostf, name, pai)) != NULL) {
2374 		cur->ai_next = p;
2375 		while (cur && cur->ai_next)
2376 			cur = cur->ai_next;
2377 	}
2378 	_endhtent(&hostf);
2379 
2380 	*((struct addrinfo **)rv) = sentinel.ai_next;
2381 	if (sentinel.ai_next == NULL)
2382 		return NS_NOTFOUND;
2383 	return NS_SUCCESS;
2384 }
2385 
2386 #ifdef YP
2387 /*ARGSUSED*/
2388 static struct addrinfo *
2389 _yphostent(char *line, const struct addrinfo *pai)
2390 {
2391 	struct addrinfo sentinel, *cur;
2392 	struct addrinfo hints, *res, *res0;
2393 	int error;
2394 	char *p;
2395 	const char *addr, *canonname;
2396 	char *nextline;
2397 	char *cp;
2398 
2399 	_DIAGASSERT(line != NULL);
2400 	_DIAGASSERT(pai != NULL);
2401 
2402 	p = line;
2403 	addr = canonname = NULL;
2404 
2405 	memset(&sentinel, 0, sizeof(sentinel));
2406 	cur = &sentinel;
2407 
2408 nextline:
2409 	/* terminate line */
2410 	cp = strchr(p, '\n');
2411 	if (cp) {
2412 		*cp++ = '\0';
2413 		nextline = cp;
2414 	} else
2415 		nextline = NULL;
2416 
2417 	cp = strpbrk(p, " \t");
2418 	if (cp == NULL) {
2419 		if (canonname == NULL)
2420 			return (NULL);
2421 		else
2422 			goto done;
2423 	}
2424 	*cp++ = '\0';
2425 
2426 	addr = p;
2427 
2428 	while (cp && *cp) {
2429 		if (*cp == ' ' || *cp == '\t') {
2430 			cp++;
2431 			continue;
2432 		}
2433 		if (!canonname)
2434 			canonname = cp;
2435 		if ((cp = strpbrk(cp, " \t")) != NULL)
2436 			*cp++ = '\0';
2437 	}
2438 
2439 	hints = *pai;
2440 	hints.ai_flags = AI_NUMERICHOST;
2441 	error = getaddrinfo(addr, NULL, &hints, &res0);
2442 	if (error == 0) {
2443 		for (res = res0; res; res = res->ai_next) {
2444 			/* cover it up */
2445 			res->ai_flags = pai->ai_flags;
2446 
2447 			if (pai->ai_flags & AI_CANONNAME)
2448 				(void)get_canonname(pai, res, canonname);
2449 		}
2450 	} else
2451 		res0 = NULL;
2452 	if (res0) {
2453 		cur->ai_next = res0;
2454 		while (cur->ai_next)
2455 			cur = cur->ai_next;
2456 	}
2457 
2458 	if (nextline) {
2459 		p = nextline;
2460 		goto nextline;
2461 	}
2462 
2463 done:
2464 	return sentinel.ai_next;
2465 }
2466 
2467 /*ARGSUSED*/
2468 static int
2469 _yp_getaddrinfo(void *rv, void *cb_data, va_list ap)
2470 {
2471 	struct addrinfo sentinel, *cur;
2472 	struct addrinfo *ai = NULL;
2473 	char *ypbuf;
2474 	int ypbuflen, r;
2475 	const char *name;
2476 	const struct addrinfo *pai;
2477 	char *ypdomain;
2478 
2479 	if (_yp_check(&ypdomain) == 0)
2480 		return NS_UNAVAIL;
2481 
2482 	name = va_arg(ap, char *);
2483 	pai = va_arg(ap, const struct addrinfo *);
2484 
2485 	memset(&sentinel, 0, sizeof(sentinel));
2486 	cur = &sentinel;
2487 
2488 	/* hosts.byname is only for IPv4 (Solaris8) */
2489 	if (pai->ai_family == PF_UNSPEC || pai->ai_family == PF_INET) {
2490 		r = yp_match(ypdomain, "hosts.byname", name,
2491 			(int)strlen(name), &ypbuf, &ypbuflen);
2492 		if (r == 0) {
2493 			struct addrinfo ai4;
2494 
2495 			ai4 = *pai;
2496 			ai4.ai_family = AF_INET;
2497 			ai = _yphostent(ypbuf, &ai4);
2498 			if (ai) {
2499 				cur->ai_next = ai;
2500 				while (cur && cur->ai_next)
2501 					cur = cur->ai_next;
2502 			}
2503 		}
2504 		free(ypbuf);
2505 	}
2506 
2507 	/* ipnodes.byname can hold both IPv4/v6 */
2508 	r = yp_match(ypdomain, "ipnodes.byname", name,
2509 		(int)strlen(name), &ypbuf, &ypbuflen);
2510 	if (r == 0) {
2511 		ai = _yphostent(ypbuf, pai);
2512 		if (ai)
2513 			cur->ai_next = ai;
2514 		free(ypbuf);
2515 	}
2516 
2517 	if (sentinel.ai_next == NULL) {
2518 		h_errno = HOST_NOT_FOUND;
2519 		return NS_NOTFOUND;
2520 	}
2521 	*((struct addrinfo **)rv) = sentinel.ai_next;
2522 	return NS_SUCCESS;
2523 }
2524 #endif
2525 
2526 /* resolver logic */
2527 
2528 /*
2529  * Formulate a normal query, send, and await answer.
2530  * Returned answer is placed in supplied buffer "answer".
2531  * Perform preliminary check of answer, returning success only
2532  * if no error is indicated and the answer count is nonzero.
2533  * Return the size of the response on success, -1 on error.
2534  * Error number is left in h_errno.
2535  *
2536  * Caller must parse answer and determine whether it answers the question.
2537  */
2538 static int
2539 res_queryN(const char *name, /* domain name */ struct res_target *target,
2540     res_state res)
2541 {
2542 	u_char buf[MAXPACKET];
2543 	HEADER *hp;
2544 	int n;
2545 	struct res_target *t;
2546 	int rcode;
2547 	int ancount;
2548 
2549 	_DIAGASSERT(name != NULL);
2550 	/* XXX: target may be NULL??? */
2551 
2552 	rcode = NOERROR;
2553 	ancount = 0;
2554 
2555 	for (t = target; t; t = t->next) {
2556 		int class, type;
2557 		u_char *answer;
2558 		int anslen;
2559 
2560 		hp = (HEADER *)(void *)t->answer;
2561 		hp->rcode = NOERROR;	/* default */
2562 
2563 		/* make it easier... */
2564 		class = t->qclass;
2565 		type = t->qtype;
2566 		answer = t->answer;
2567 		anslen = t->anslen;
2568 #ifdef DEBUG
2569 		if (res->options & RES_DEBUG)
2570 			printf(";; res_nquery(%s, %d, %d)\n", name, class, type);
2571 #endif
2572 
2573 		n = res_nmkquery(res, QUERY, name, class, type, NULL, 0, NULL,
2574 		    buf, (int)sizeof(buf));
2575 #ifdef RES_USE_EDNS0
2576 		if (n > 0 && (res->options & RES_USE_EDNS0) != 0)
2577 			n = res_nopt(res, n, buf, (int)sizeof(buf), anslen);
2578 #endif
2579 		if (n <= 0) {
2580 #ifdef DEBUG
2581 			if (res->options & RES_DEBUG)
2582 				printf(";; res_nquery: mkquery failed\n");
2583 #endif
2584 			h_errno = NO_RECOVERY;
2585 			return n;
2586 		}
2587 		n = res_nsend(res, buf, n, answer, anslen);
2588 #if 0
2589 		if (n < 0) {
2590 #ifdef DEBUG
2591 			if (res->options & RES_DEBUG)
2592 				printf(";; res_query: send error\n");
2593 #endif
2594 			h_errno = TRY_AGAIN;
2595 			return n;
2596 		}
2597 #endif
2598 
2599 		if (n < 0 || hp->rcode != NOERROR || ntohs(hp->ancount) == 0) {
2600 			rcode = hp->rcode;	/* record most recent error */
2601 #ifdef DEBUG
2602 			if (res->options & RES_DEBUG)
2603 				printf(";; rcode = %u, ancount=%u\n", hp->rcode,
2604 				    ntohs(hp->ancount));
2605 #endif
2606 			continue;
2607 		}
2608 
2609 		ancount += ntohs(hp->ancount);
2610 
2611 		t->n = n;
2612 	}
2613 
2614 	if (ancount == 0) {
2615 		switch (rcode) {
2616 		case NXDOMAIN:
2617 			h_errno = HOST_NOT_FOUND;
2618 			break;
2619 		case SERVFAIL:
2620 			h_errno = TRY_AGAIN;
2621 			break;
2622 		case NOERROR:
2623 			h_errno = NO_DATA;
2624 			break;
2625 		case FORMERR:
2626 		case NOTIMP:
2627 		case REFUSED:
2628 		default:
2629 			h_errno = NO_RECOVERY;
2630 			break;
2631 		}
2632 		return -1;
2633 	}
2634 	return ancount;
2635 }
2636 
2637 /*
2638  * Formulate a normal query, send, and retrieve answer in supplied buffer.
2639  * Return the size of the response on success, -1 on error.
2640  * If enabled, implement search rules until answer or unrecoverable failure
2641  * is detected.	 Error code, if any, is left in h_errno.
2642  */
2643 static int
2644 res_searchN(const char *name, struct res_target *target, res_state res)
2645 {
2646 	const char *cp, * const *domain;
2647 	HEADER *hp;
2648 	u_int dots;
2649 	char buf[MAXHOSTNAMELEN];
2650 	int trailing_dot, ret, saved_herrno;
2651 	int got_nodata = 0, got_servfail = 0, tried_as_is = 0;
2652 
2653 	_DIAGASSERT(name != NULL);
2654 	_DIAGASSERT(target != NULL);
2655 
2656 	hp = (HEADER *)(void *)target->answer;	/*XXX*/
2657 
2658 	errno = 0;
2659 	h_errno = HOST_NOT_FOUND;	/* default, if we never query */
2660 	dots = 0;
2661 	for (cp = name; *cp; cp++)
2662 		dots += (*cp == '.');
2663 	trailing_dot = 0;
2664 	if (cp > name && *--cp == '.')
2665 		trailing_dot++;
2666 
2667 	/*
2668 	 * if there aren't any dots, it could be a user-level alias
2669 	 */
2670 	if (!dots && (cp = res_hostalias(res, name, buf, sizeof(buf))) != NULL) {
2671 		ret = res_queryN(cp, target, res);
2672 		return ret;
2673 	}
2674 
2675 	/*
2676 	 * If there are dots in the name already, let's just give it a try
2677 	 * 'as is'.  The threshold can be set with the "ndots" option.
2678 	 */
2679 	saved_herrno = -1;
2680 	if (dots >= res->ndots) {
2681 		ret = res_querydomainN(name, NULL, target, res);
2682 		if (ret > 0)
2683 			return (ret);
2684 		saved_herrno = h_errno;
2685 		tried_as_is++;
2686 	}
2687 
2688 	/*
2689 	 * We do at least one level of search if
2690 	 *	- there is no dot and RES_DEFNAME is set, or
2691 	 *	- there is at least one dot, there is no trailing dot,
2692 	 *	  and RES_DNSRCH is set.
2693 	 */
2694 	if ((!dots && (res->options & RES_DEFNAMES)) ||
2695 	    (dots && !trailing_dot && (res->options & RES_DNSRCH))) {
2696 		int done = 0;
2697 
2698 		for (domain = (const char * const *)res->dnsrch;
2699 		   *domain && !done;
2700 		   domain++) {
2701 
2702 			ret = res_querydomainN(name, *domain, target, res);
2703 			if (ret > 0)
2704 				return ret;
2705 
2706 			/*
2707 			 * If no server present, give up.
2708 			 * If name isn't found in this domain,
2709 			 * keep trying higher domains in the search list
2710 			 * (if that's enabled).
2711 			 * On a NO_DATA error, keep trying, otherwise
2712 			 * a wildcard entry of another type could keep us
2713 			 * from finding this entry higher in the domain.
2714 			 * If we get some other error (negative answer or
2715 			 * server failure), then stop searching up,
2716 			 * but try the input name below in case it's
2717 			 * fully-qualified.
2718 			 */
2719 			if (errno == ECONNREFUSED) {
2720 				h_errno = TRY_AGAIN;
2721 				return -1;
2722 			}
2723 
2724 			switch (h_errno) {
2725 			case NO_DATA:
2726 				got_nodata++;
2727 				/* FALLTHROUGH */
2728 			case HOST_NOT_FOUND:
2729 				/* keep trying */
2730 				break;
2731 			case TRY_AGAIN:
2732 				if (hp->rcode == SERVFAIL) {
2733 					/* try next search element, if any */
2734 					got_servfail++;
2735 					break;
2736 				}
2737 				/* FALLTHROUGH */
2738 			default:
2739 				/* anything else implies that we're done */
2740 				done++;
2741 			}
2742 			/*
2743 			 * if we got here for some reason other than DNSRCH,
2744 			 * we only wanted one iteration of the loop, so stop.
2745 			 */
2746 			if (!(res->options & RES_DNSRCH))
2747 				done++;
2748 		}
2749 	}
2750 
2751 	/*
2752 	 * if we have not already tried the name "as is", do that now.
2753 	 * note that we do this regardless of how many dots were in the
2754 	 * name or whether it ends with a dot.
2755 	 */
2756 	if (!tried_as_is) {
2757 		ret = res_querydomainN(name, NULL, target, res);
2758 		if (ret > 0)
2759 			return ret;
2760 	}
2761 
2762 	/*
2763 	 * if we got here, we didn't satisfy the search.
2764 	 * if we did an initial full query, return that query's h_errno
2765 	 * (note that we wouldn't be here if that query had succeeded).
2766 	 * else if we ever got a nodata, send that back as the reason.
2767 	 * else send back meaningless h_errno, that being the one from
2768 	 * the last DNSRCH we did.
2769 	 */
2770 	if (saved_herrno != -1)
2771 		h_errno = saved_herrno;
2772 	else if (got_nodata)
2773 		h_errno = NO_DATA;
2774 	else if (got_servfail)
2775 		h_errno = TRY_AGAIN;
2776 	return -1;
2777 }
2778 
2779 /*
2780  * Perform a call on res_query on the concatenation of name and domain,
2781  * removing a trailing dot from name if domain is NULL.
2782  */
2783 static int
2784 res_querydomainN(const char *name, const char *domain,
2785     struct res_target *target, res_state res)
2786 {
2787 	char nbuf[MAXDNAME];
2788 	const char *longname = nbuf;
2789 	size_t n, d;
2790 
2791 	_DIAGASSERT(name != NULL);
2792 	/* XXX: target may be NULL??? */
2793 
2794 #ifdef DEBUG
2795 	if (res->options & RES_DEBUG)
2796 		printf(";; res_querydomain(%s, %s)\n",
2797 			name, domain?domain:"<Nil>");
2798 #endif
2799 	if (domain == NULL) {
2800 		/*
2801 		 * Check for trailing '.';
2802 		 * copy without '.' if present.
2803 		 */
2804 		n = strlen(name);
2805 		if (n + 1 > sizeof(nbuf)) {
2806 			h_errno = NO_RECOVERY;
2807 			return -1;
2808 		}
2809 		if (n > 0 && name[--n] == '.') {
2810 			strncpy(nbuf, name, n);
2811 			nbuf[n] = '\0';
2812 		} else
2813 			longname = name;
2814 	} else {
2815 		n = strlen(name);
2816 		d = strlen(domain);
2817 		if (n + 1 + d + 1 > sizeof(nbuf)) {
2818 			h_errno = NO_RECOVERY;
2819 			return -1;
2820 		}
2821 		snprintf(nbuf, sizeof(nbuf), "%s.%s", name, domain);
2822 	}
2823 	return res_queryN(longname, target, res);
2824 }
2825 
2826 #ifdef TEST
2827 int
2828 main(int argc, char *argv[]) {
2829 	struct addrinfo *ai, *sai;
2830 	int i, e;
2831 	char buf[1024];
2832 
2833 	for (i = 1; i < argc; i++) {
2834 		if ((e = getaddrinfo(argv[i], NULL, NULL, &sai)) != 0)
2835 			warnx("%s: %s", argv[i], gai_strerror(e));
2836 		for (ai = sai; ai; ai = ai->ai_next) {
2837 			sockaddr_snprintf(buf, sizeof(buf), "%a", ai->ai_addr);
2838              		printf("flags=0x%x family=%d socktype=%d protocol=%d "
2839 			    "addrlen=%zu addr=%s canonname=%s next=%p\n",
2840 			    ai->ai_flags,
2841              		    ai->ai_family,
2842              		    ai->ai_socktype,
2843              		    ai->ai_protocol,
2844              		    (size_t)ai->ai_addrlen,
2845 			    buf,
2846 			    ai->ai_canonname,
2847 			    ai->ai_next);
2848 		}
2849 		if (sai)
2850 			freeaddrinfo(sai);
2851 	}
2852 	return 0;
2853 }
2854 #endif
2855