xref: /openbsd-src/lib/libc/asr/getaddrinfo_async.c (revision 3374c67d44f9b75b98444cbf63020f777792342e)
1 /*	$OpenBSD: getaddrinfo_async.c,v 1.59 2022/12/27 17:10:06 jmc Exp $	*/
2 /*
3  * Copyright (c) 2012 Eric Faurot <eric@openbsd.org>
4  *
5  * Permission to use, copy, modify, and distribute this software for any
6  * purpose with or without fee is hereby granted, provided that the above
7  * copyright notice and this permission notice appear in all copies.
8  *
9  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16  */
17 
18 #include <sys/types.h>
19 #include <sys/socket.h>
20 #include <sys/uio.h>
21 #include <netinet/in.h>
22 #include <arpa/nameser.h>
23 #include <net/if.h>
24 #include <netdb.h>
25 
26 #include <asr.h>
27 #include <errno.h>
28 #include <ifaddrs.h>
29 #include <resolv.h>
30 #include <stdlib.h>
31 #include <string.h>
32 #include <unistd.h>
33 #include <limits.h>
34 
35 #include "asr_private.h"
36 
37 struct match {
38 	int family;
39 	int socktype;
40 	int protocol;
41 };
42 
43 static int getaddrinfo_async_run(struct asr_query *, struct asr_result *);
44 static int get_port(const char *, const char *, int);
45 static int iter_family(struct asr_query *, int);
46 static int addrinfo_add(struct asr_query *, const struct sockaddr *, const char *);
47 static int addrinfo_from_file(struct asr_query *, int,  FILE *);
48 static int addrinfo_from_pkt(struct asr_query *, char *, size_t);
49 static int addrconfig_setup(struct asr_query *);
50 
51 static const struct match matches[] = {
52 	{ PF_INET,	SOCK_DGRAM,	IPPROTO_UDP	},
53 	{ PF_INET,	SOCK_STREAM,	IPPROTO_TCP	},
54 	{ PF_INET,	SOCK_RAW,	0		},
55 	{ PF_INET6,	SOCK_DGRAM,	IPPROTO_UDP	},
56 	{ PF_INET6,	SOCK_STREAM,	IPPROTO_TCP	},
57 	{ PF_INET6,	SOCK_RAW,	0		},
58 	{ -1,		0,		0,		},
59 };
60 
61 #define MATCH_FAMILY(a, b) ((a) == matches[(b)].family || (a) == PF_UNSPEC)
62 #define MATCH_PROTO(a, b) ((a) == matches[(b)].protocol || (a) == 0 || matches[(b)].protocol == 0)
63 /* Do not match SOCK_RAW unless explicitly specified */
64 #define MATCH_SOCKTYPE(a, b) ((a) == matches[(b)].socktype || ((a) == 0 && \
65 				matches[(b)].socktype != SOCK_RAW))
66 
67 enum {
68 	DOM_INIT,
69 	DOM_DOMAIN,
70 	DOM_DONE
71 };
72 
73 struct asr_query *
74 getaddrinfo_async(const char *hostname, const char *servname,
75 	const struct addrinfo *hints, void *asr)
76 {
77 	struct asr_ctx		*ac;
78 	struct asr_query	*as;
79 
80 	if (hints == NULL || (hints->ai_flags & AI_NUMERICHOST) == 0)
81 		ac = _asr_use_resolver(asr);
82 	else
83 		ac = _asr_no_resolver();
84 	if ((as = _asr_async_new(ac, ASR_GETADDRINFO)) == NULL)
85 		goto abort; /* errno set */
86 	as->as_run = getaddrinfo_async_run;
87 
88 	if (hostname) {
89 		if ((as->as.ai.hostname = strdup(hostname)) == NULL)
90 			goto abort; /* errno set */
91 	}
92 	if (servname && (as->as.ai.servname = strdup(servname)) == NULL)
93 		goto abort; /* errno set */
94 	if (hints)
95 		memmove(&as->as.ai.hints, hints, sizeof *hints);
96 	else {
97 		memset(&as->as.ai.hints, 0, sizeof as->as.ai.hints);
98 		as->as.ai.hints.ai_family = PF_UNSPEC;
99 		as->as.ai.hints.ai_flags = AI_ADDRCONFIG;
100 	}
101 
102 	_asr_ctx_unref(ac);
103 	return (as);
104     abort:
105 	if (as)
106 		_asr_async_free(as);
107 	_asr_ctx_unref(ac);
108 	return (NULL);
109 }
110 DEF_WEAK(getaddrinfo_async);
111 
112 static int
113 getaddrinfo_async_run(struct asr_query *as, struct asr_result *ar)
114 {
115 	char		 fqdn[MAXDNAME];
116 	const char	*str;
117 	struct addrinfo	*ai;
118 	int		 i, family, r;
119 	FILE		*f;
120 	union {
121 		struct sockaddr		sa;
122 		struct sockaddr_in	sain;
123 		struct sockaddr_in6	sain6;
124 	} sa;
125 
126     next:
127 	switch (as->as_state) {
128 
129 	case ASR_STATE_INIT:
130 
131 		/*
132 		 * First, make sure the parameters are valid.
133 		 */
134 
135 		as->as_count = 0;
136 
137 		if (as->as.ai.hostname == NULL &&
138 		    as->as.ai.servname == NULL) {
139 			ar->ar_gai_errno = EAI_NONAME;
140 			async_set_state(as, ASR_STATE_HALT);
141 			break;
142 		}
143 
144 		if (as->as.ai.hostname && as->as.ai.hostname[0] == '\0') {
145 			ar->ar_gai_errno = EAI_NODATA;
146 			async_set_state(as, ASR_STATE_HALT);
147 			break;
148 		}
149 
150 		ai = &as->as.ai.hints;
151 
152 		if (ai->ai_addrlen ||
153 		    ai->ai_canonname ||
154 		    ai->ai_addr ||
155 		    ai->ai_next) {
156 			ar->ar_gai_errno = EAI_BADHINTS;
157 			async_set_state(as, ASR_STATE_HALT);
158 			break;
159 		}
160 
161 		if (ai->ai_flags & ~AI_MASK ||
162 		    (ai->ai_flags & AI_CANONNAME && ai->ai_flags & AI_FQDN)) {
163 			ar->ar_gai_errno = EAI_BADFLAGS;
164 			async_set_state(as, ASR_STATE_HALT);
165 			break;
166 		}
167 
168 		if (ai->ai_family != PF_UNSPEC &&
169 		    ai->ai_family != PF_INET &&
170 		    ai->ai_family != PF_INET6) {
171 			ar->ar_gai_errno = EAI_FAMILY;
172 			async_set_state(as, ASR_STATE_HALT);
173 			break;
174 		}
175 
176 		if (ai->ai_socktype &&
177 		    ai->ai_socktype != SOCK_DGRAM  &&
178 		    ai->ai_socktype != SOCK_STREAM &&
179 		    ai->ai_socktype != SOCK_RAW) {
180 			ar->ar_gai_errno = EAI_SOCKTYPE;
181 			async_set_state(as, ASR_STATE_HALT);
182 			break;
183 		}
184 
185 		if (ai->ai_socktype == SOCK_RAW &&
186 		    get_port(as->as.ai.servname, NULL, 1) != 0) {
187 			ar->ar_gai_errno = EAI_SERVICE;
188 			async_set_state(as, ASR_STATE_HALT);
189 			break;
190 		}
191 
192 		/* Restrict result set to configured address families */
193 		if (ai->ai_flags & AI_ADDRCONFIG) {
194 			if (addrconfig_setup(as) == -1) {
195 				ar->ar_errno = errno;
196 				ar->ar_gai_errno = EAI_SYSTEM;
197 				async_set_state(as, ASR_STATE_HALT);
198 				break;
199 			}
200 		}
201 
202 		/* Make sure there is at least a valid combination */
203 		for (i = 0; matches[i].family != -1; i++)
204 			if (MATCH_FAMILY(ai->ai_family, i) &&
205 			    MATCH_SOCKTYPE(ai->ai_socktype, i) &&
206 			    MATCH_PROTO(ai->ai_protocol, i))
207 				break;
208 		if (matches[i].family == -1) {
209 			ar->ar_gai_errno = EAI_BADHINTS;
210 			async_set_state(as, ASR_STATE_HALT);
211 			break;
212 		}
213 
214 		if (ai->ai_protocol == 0 || ai->ai_protocol == IPPROTO_UDP)
215 			as->as.ai.port_udp = get_port(as->as.ai.servname, "udp",
216 			    as->as.ai.hints.ai_flags & AI_NUMERICSERV);
217 		if (ai->ai_protocol == 0 || ai->ai_protocol == IPPROTO_TCP)
218 			as->as.ai.port_tcp = get_port(as->as.ai.servname, "tcp",
219 			    as->as.ai.hints.ai_flags & AI_NUMERICSERV);
220 		if (as->as.ai.port_tcp == -2 || as->as.ai.port_udp == -2 ||
221 		    (as->as.ai.port_tcp == -1 && as->as.ai.port_udp == -1) ||
222 		    (ai->ai_protocol && (as->as.ai.port_udp == -1 ||
223 					 as->as.ai.port_tcp == -1))) {
224 			ar->ar_gai_errno = EAI_SERVICE;
225 			async_set_state(as, ASR_STATE_HALT);
226 			break;
227 		}
228 
229 		ar->ar_gai_errno = 0;
230 
231 		/* If hostname is NULL, use local address */
232 		if (as->as.ai.hostname == NULL) {
233 			for (family = iter_family(as, 1);
234 			    family != -1;
235 			    family = iter_family(as, 0)) {
236 				/*
237 				 * We could use statically built sockaddrs for
238 				 * those, rather than parsing over and over.
239 				 */
240 				if (family == PF_INET)
241 					str = (ai->ai_flags & AI_PASSIVE) ? \
242 						"0.0.0.0" : "127.0.0.1";
243 				else /* PF_INET6 */
244 					str = (ai->ai_flags & AI_PASSIVE) ? \
245 						"::" : "::1";
246 				 /* This can't fail */
247 				_asr_sockaddr_from_str(&sa.sa, family, str);
248 				if ((r = addrinfo_add(as, &sa.sa, NULL))) {
249 					ar->ar_gai_errno = r;
250 					break;
251 				}
252 			}
253 			if (ar->ar_gai_errno == 0 && as->as_count == 0) {
254 				ar->ar_gai_errno = EAI_NODATA;
255 			}
256 			async_set_state(as, ASR_STATE_HALT);
257 			break;
258 		}
259 
260 		/* Try numeric addresses first */
261 		for (family = iter_family(as, 1);
262 		    family != -1;
263 		    family = iter_family(as, 0)) {
264 
265 			if (_asr_sockaddr_from_str(&sa.sa, family,
266 			    as->as.ai.hostname) == -1)
267 				continue;
268 
269 			if ((r = addrinfo_add(as, &sa.sa, NULL)))
270 				ar->ar_gai_errno = r;
271 			break;
272 		}
273 		if (ar->ar_gai_errno || as->as_count) {
274 			async_set_state(as, ASR_STATE_HALT);
275 			break;
276 		}
277 
278 		if (ai->ai_flags & AI_NUMERICHOST) {
279 			ar->ar_gai_errno = EAI_NONAME;
280 			async_set_state(as, ASR_STATE_HALT);
281 			break;
282 		}
283 
284 		/* make sure there are no funny characters in hostname */
285 		if (!hnok_lenient(as->as.ai.hostname)) {
286 			ar->ar_gai_errno = EAI_FAIL;
287 			async_set_state(as, ASR_STATE_HALT);
288 			break;
289 		}
290 
291 		async_set_state(as, ASR_STATE_NEXT_DB);
292 		break;
293 
294 	case ASR_STATE_NEXT_DB:
295 		if (_asr_iter_db(as) == -1) {
296 			async_set_state(as, ASR_STATE_NOT_FOUND);
297 			break;
298 		}
299 		as->as_family_idx = 0;
300 		async_set_state(as, ASR_STATE_SAME_DB);
301 		break;
302 
303 	case ASR_STATE_NEXT_FAMILY:
304 		as->as_family_idx += 1;
305 		if (as->as.ai.hints.ai_family != AF_UNSPEC ||
306 		    AS_FAMILY(as) == -1) {
307 			/* The family was specified, or we have tried all
308 			 * families with this DB.
309 			 */
310 			if (as->as_count) {
311 				ar->ar_gai_errno = 0;
312 				async_set_state(as, ASR_STATE_HALT);
313 			} else
314 				async_set_state(as, ASR_STATE_NEXT_DOMAIN);
315 			break;
316 		}
317 		async_set_state(as, ASR_STATE_SAME_DB);
318 		break;
319 
320 	case ASR_STATE_NEXT_DOMAIN:
321 		/* domain search is only for dns */
322 		if (AS_DB(as) != ASR_DB_DNS) {
323 			async_set_state(as, ASR_STATE_NEXT_DB);
324 			break;
325 		}
326 		as->as_family_idx = 0;
327 
328 		free(as->as.ai.fqdn);
329 		as->as.ai.fqdn = NULL;
330 		r = _asr_iter_domain(as, as->as.ai.hostname, fqdn, sizeof(fqdn));
331 		if (r == -1) {
332 			async_set_state(as, ASR_STATE_NEXT_DB);
333 			break;
334 		}
335 		if (r == 0) {
336 			ar->ar_gai_errno = EAI_FAIL;
337 			async_set_state(as, ASR_STATE_HALT);
338 			break;
339 		}
340 		as->as.ai.fqdn = strdup(fqdn);
341 		if (as->as.ai.fqdn == NULL) {
342 			ar->ar_gai_errno = EAI_MEMORY;
343 			async_set_state(as, ASR_STATE_HALT);
344 			break;
345 		}
346 
347 		async_set_state(as, ASR_STATE_SAME_DB);
348 		break;
349 
350 	case ASR_STATE_SAME_DB:
351 		/* query the current DB again */
352 		switch (AS_DB(as)) {
353 		case ASR_DB_DNS:
354 			if (as->as.ai.fqdn == NULL) {
355 				/* First try, initialize domain iteration */
356 				as->as_dom_flags = 0;
357 				as->as_dom_step = DOM_INIT;
358 				async_set_state(as, ASR_STATE_NEXT_DOMAIN);
359 				break;
360 			}
361 
362 			family = (as->as.ai.hints.ai_family == AF_UNSPEC) ?
363 			    AS_FAMILY(as) : as->as.ai.hints.ai_family;
364 
365 			if (family == AF_INET &&
366 			    as->as_flags & ASYNC_NO_INET) {
367 				async_set_state(as, ASR_STATE_NEXT_FAMILY);
368 				break;
369 			} else if (family == AF_INET6 &&
370 			    as->as_flags & ASYNC_NO_INET6) {
371 				async_set_state(as, ASR_STATE_NEXT_FAMILY);
372 				break;
373 			}
374 
375 			as->as_subq = _res_query_async_ctx(as->as.ai.fqdn,
376 			    C_IN, (family == AF_INET6) ? T_AAAA : T_A,
377 			    as->as_ctx);
378 
379 			if (as->as_subq == NULL) {
380 				if (errno == ENOMEM)
381 					ar->ar_gai_errno = EAI_MEMORY;
382 				else
383 					ar->ar_gai_errno = EAI_FAIL;
384 				async_set_state(as, ASR_STATE_HALT);
385 				break;
386 			}
387 			async_set_state(as, ASR_STATE_SUBQUERY);
388 			break;
389 
390 		case ASR_DB_FILE:
391 			f = fopen(_PATH_HOSTS, "re");
392 			if (f == NULL) {
393 				async_set_state(as, ASR_STATE_NEXT_DB);
394 				break;
395 			}
396 			family = (as->as.ai.hints.ai_family == AF_UNSPEC) ?
397 			    AS_FAMILY(as) : as->as.ai.hints.ai_family;
398 
399 			r = addrinfo_from_file(as, family, f);
400 			if (r == -1) {
401 				if (errno == ENOMEM)
402 					ar->ar_gai_errno = EAI_MEMORY;
403 				else
404 					ar->ar_gai_errno = EAI_FAIL;
405 				async_set_state(as, ASR_STATE_HALT);
406 			} else
407 				async_set_state(as, ASR_STATE_NEXT_FAMILY);
408 			fclose(f);
409 			break;
410 
411 		default:
412 			async_set_state(as, ASR_STATE_NEXT_DB);
413 		}
414 		break;
415 
416 	case ASR_STATE_SUBQUERY:
417 		if ((r = asr_run(as->as_subq, ar)) == ASYNC_COND)
418 			return (ASYNC_COND);
419 
420 		as->as_subq = NULL;
421 
422 		if (ar->ar_datalen == -1) {
423 			async_set_state(as, ASR_STATE_NEXT_FAMILY);
424 			break;
425 		}
426 
427 		r = addrinfo_from_pkt(as, ar->ar_data, ar->ar_datalen);
428 		if (r == -1) {
429 			if (errno == ENOMEM)
430 				ar->ar_gai_errno = EAI_MEMORY;
431 			else
432 				ar->ar_gai_errno = EAI_FAIL;
433 			async_set_state(as, ASR_STATE_HALT);
434 		} else
435 			async_set_state(as, ASR_STATE_NEXT_FAMILY);
436 		free(ar->ar_data);
437 		break;
438 
439 	case ASR_STATE_NOT_FOUND:
440 		/* No result found. Maybe we can try again. */
441 		if (as->as_flags & ASYNC_AGAIN)
442 			ar->ar_gai_errno = EAI_AGAIN;
443 		else
444 			ar->ar_gai_errno = EAI_NODATA;
445 		async_set_state(as, ASR_STATE_HALT);
446 		break;
447 
448 	case ASR_STATE_HALT:
449 		if (ar->ar_gai_errno == 0) {
450 			ar->ar_count = as->as_count;
451 			ar->ar_addrinfo = as->as.ai.aifirst;
452 			as->as.ai.aifirst = NULL;
453 		} else {
454 			ar->ar_count = 0;
455 			ar->ar_addrinfo = NULL;
456 		}
457 		return (ASYNC_DONE);
458 
459 	default:
460 		ar->ar_errno = EOPNOTSUPP;
461 		ar->ar_gai_errno = EAI_SYSTEM;
462 		async_set_state(as, ASR_STATE_HALT);
463 		break;
464 	}
465 	goto next;
466 }
467 
468 /*
469  * Retrieve the port number for the service name "servname" and
470  * the protocol "proto".
471  */
472 static int
473 get_port(const char *servname, const char *proto, int numonly)
474 {
475 	struct servent		se;
476 	struct servent_data	sed;
477 	int			port;
478 	const char		*e;
479 
480 	if (servname == NULL)
481 		return (0);
482 
483 	e = NULL;
484 	port = strtonum(servname, 0, USHRT_MAX, &e);
485 	if (e == NULL)
486 		return (port);
487 	if (errno == ERANGE)
488 		return (-2); /* invalid */
489 	if (numonly)
490 		return (-2);
491 
492 	port = -1;
493 	memset(&sed, 0, sizeof(sed));
494 	if (getservbyname_r(servname, proto, &se, &sed) != -1)
495 		port = ntohs(se.s_port);
496 	endservent_r(&sed);
497 
498 	return (port);
499 }
500 
501 /*
502  * Iterate over the address families that are to be queried. Use the
503  * list on the async context, unless a specific family was given in hints.
504  */
505 static int
506 iter_family(struct asr_query *as, int first)
507 {
508 	if (first) {
509 		as->as_family_idx = 0;
510 		if (as->as.ai.hints.ai_family != PF_UNSPEC)
511 			return as->as.ai.hints.ai_family;
512 		return AS_FAMILY(as);
513 	}
514 
515 	if (as->as.ai.hints.ai_family != PF_UNSPEC)
516 		return (-1);
517 
518 	as->as_family_idx++;
519 
520 	return AS_FAMILY(as);
521 }
522 
523 /*
524  * Use the sockaddr at "sa" to extend the result list on the "as" context,
525  * with the specified canonical name "cname". This function adds one
526  * entry per protocol/socktype match.
527  */
528 static int
529 addrinfo_add(struct asr_query *as, const struct sockaddr *sa, const char *cname)
530 {
531 	struct addrinfo		*ai;
532 	int			 i, port, proto;
533 
534 	for (i = 0; matches[i].family != -1; i++) {
535 		if (matches[i].family != sa->sa_family ||
536 		    !MATCH_SOCKTYPE(as->as.ai.hints.ai_socktype, i) ||
537 		    !MATCH_PROTO(as->as.ai.hints.ai_protocol, i))
538 			continue;
539 
540 		proto = as->as.ai.hints.ai_protocol;
541 		if (!proto)
542 			proto = matches[i].protocol;
543 
544 		if (proto == IPPROTO_TCP)
545 			port = as->as.ai.port_tcp;
546 		else if (proto == IPPROTO_UDP)
547 			port = as->as.ai.port_udp;
548 		else
549 			port = 0;
550 
551 		/* servname specified, but not defined for this protocol */
552 		if (port == -1)
553 			continue;
554 
555 		ai = calloc(1, sizeof(*ai) + sa->sa_len);
556 		if (ai == NULL)
557 			return (EAI_MEMORY);
558 		ai->ai_family = sa->sa_family;
559 		ai->ai_socktype = matches[i].socktype;
560 		ai->ai_protocol = proto;
561 		ai->ai_flags = as->as.ai.hints.ai_flags;
562 		ai->ai_addrlen = sa->sa_len;
563 		ai->ai_addr = (void *)(ai + 1);
564 		if (cname &&
565 		    as->as.ai.hints.ai_flags & (AI_CANONNAME | AI_FQDN)) {
566 			if ((ai->ai_canonname = strdup(cname)) == NULL) {
567 				free(ai);
568 				return (EAI_MEMORY);
569 			}
570 		}
571 		memmove(ai->ai_addr, sa, sa->sa_len);
572 		if (sa->sa_family == PF_INET)
573 			((struct sockaddr_in *)ai->ai_addr)->sin_port =
574 			    htons(port);
575 		else if (sa->sa_family == PF_INET6)
576 			((struct sockaddr_in6 *)ai->ai_addr)->sin6_port =
577 			    htons(port);
578 
579 		if (as->as.ai.aifirst == NULL)
580 			as->as.ai.aifirst = ai;
581 		if (as->as.ai.ailast)
582 			as->as.ai.ailast->ai_next = ai;
583 		as->as.ai.ailast = ai;
584 		as->as_count += 1;
585 	}
586 
587 	return (0);
588 }
589 
590 static int
591 addrinfo_from_file(struct asr_query *as, int family, FILE *f)
592 {
593 	char		*tokens[MAXTOKEN], *c, buf[BUFSIZ + 1];
594 	int		 n, i;
595 	union {
596 		struct sockaddr		sa;
597 		struct sockaddr_in	sain;
598 		struct sockaddr_in6	sain6;
599 	} u;
600 
601 	for (;;) {
602 		n = _asr_parse_namedb_line(f, tokens, MAXTOKEN, buf, sizeof(buf));
603 		if (n == -1)
604 			break; /* ignore errors reading the file */
605 
606 		for (i = 1; i < n; i++) {
607 			if (strcasecmp(as->as.ai.hostname, tokens[i]))
608 				continue;
609 			if (_asr_sockaddr_from_str(&u.sa, family, tokens[0]) == -1)
610 				continue;
611 			break;
612 		}
613 		if (i == n)
614 			continue;
615 
616 		if (as->as.ai.hints.ai_flags & (AI_CANONNAME | AI_FQDN))
617 			c = tokens[1];
618 		else
619 			c = NULL;
620 
621 		if (addrinfo_add(as, &u.sa, c))
622 			return (-1); /* errno set */
623 	}
624 	return (0);
625 }
626 
627 static int
628 addrinfo_from_pkt(struct asr_query *as, char *pkt, size_t pktlen)
629 {
630 	struct asr_unpack	 p;
631 	struct asr_dns_header	 h;
632 	struct asr_dns_query	 q;
633 	struct asr_dns_rr	 rr;
634 	int			 i;
635 	union {
636 		struct sockaddr		sa;
637 		struct sockaddr_in	sain;
638 		struct sockaddr_in6	sain6;
639 	} u;
640 	char		 buf[MAXDNAME], *c;
641 
642 	_asr_unpack_init(&p, pkt, pktlen);
643 	_asr_unpack_header(&p, &h);
644 	for (; h.qdcount; h.qdcount--)
645 		_asr_unpack_query(&p, &q);
646 
647 	for (i = 0; i < h.ancount; i++) {
648 		_asr_unpack_rr(&p, &rr);
649 		if (rr.rr_type != q.q_type ||
650 		    rr.rr_class != q.q_class)
651 			continue;
652 
653 		memset(&u, 0, sizeof u);
654 		if (rr.rr_type == T_A) {
655 			u.sain.sin_len = sizeof u.sain;
656 			u.sain.sin_family = AF_INET;
657 			u.sain.sin_addr = rr.rr.in_a.addr;
658 			u.sain.sin_port = 0;
659 		} else if (rr.rr_type == T_AAAA) {
660 			u.sain6.sin6_len = sizeof u.sain6;
661 			u.sain6.sin6_family = AF_INET6;
662 			u.sain6.sin6_addr = rr.rr.in_aaaa.addr6;
663 			u.sain6.sin6_port = 0;
664 		} else
665 			continue;
666 
667 		if (as->as.ai.hints.ai_flags & AI_CANONNAME) {
668 			_asr_strdname(rr.rr_dname, buf, sizeof buf);
669 			buf[strlen(buf) - 1] = '\0';
670 			c = res_hnok(buf) ? buf : NULL;
671 		} else if (as->as.ai.hints.ai_flags & AI_FQDN)
672 			c = as->as.ai.fqdn;
673 		else
674 			c = NULL;
675 
676 		if (addrinfo_add(as, &u.sa, c))
677 			return (-1); /* errno set */
678 	}
679 	return (0);
680 }
681 
682 static int
683 addrconfig_setup(struct asr_query *as)
684 {
685 	struct ifaddrs		*ifa, *ifa0;
686 	struct if_data		*ifa_data;
687 	struct sockaddr_in	*sinp;
688 	struct sockaddr_in6	*sin6p;
689 	int			 rtable, ifa_rtable = -1;
690 
691 	if (getifaddrs(&ifa0) == -1)
692 		return (-1);
693 
694 	rtable = getrtable();
695 
696 	as->as_flags |= ASYNC_NO_INET | ASYNC_NO_INET6;
697 
698 	for (ifa = ifa0; ifa != NULL; ifa = ifa->ifa_next) {
699 		if (ifa->ifa_addr == NULL)
700 			continue;
701 
702 		switch (ifa->ifa_addr->sa_family) {
703 		case PF_LINK:
704 			/* AF_LINK comes before inet / inet6 on an interface */
705 			ifa_data = (struct if_data *)ifa->ifa_data;
706 			ifa_rtable = ifa_data->ifi_rdomain;
707 			break;
708 		case PF_INET:
709 			if (ifa_rtable != rtable)
710 				continue;
711 
712 			sinp = (struct sockaddr_in *)ifa->ifa_addr;
713 
714 			if (sinp->sin_addr.s_addr == htonl(INADDR_LOOPBACK))
715 				continue;
716 
717 			as->as_flags &= ~ASYNC_NO_INET;
718 			break;
719 		case PF_INET6:
720 			if (ifa_rtable != rtable)
721 				continue;
722 
723 			sin6p = (struct sockaddr_in6 *)ifa->ifa_addr;
724 
725 			if (IN6_IS_ADDR_LOOPBACK(&sin6p->sin6_addr))
726 				continue;
727 
728 			if (IN6_IS_ADDR_LINKLOCAL(&sin6p->sin6_addr))
729 				continue;
730 
731 			as->as_flags &= ~ASYNC_NO_INET6;
732 			break;
733 		}
734 	}
735 
736 	freeifaddrs(ifa0);
737 
738 	return (0);
739 }
740