xref: /openbsd-src/lib/libc/asr/getaddrinfo_async.c (revision fada2b0bd226843a6444c75947c346f81ce1fa83)
1 /*	$OpenBSD: getaddrinfo_async.c,v 1.61 2023/11/21 15:26:56 florian 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, is_localhost = 0;
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 (!(ai->ai_flags & AI_NUMERICHOST))
232 			is_localhost = _asr_is_localhost(as->as.ai.hostname);
233 		/*
234 		 * If hostname is NULL, "localhost" or falls within the
235 		 * ".localhost." domain, use local address.
236 		 * RFC 6761, 6.3:
237 		 * 3. Name resolution APIs and libraries SHOULD recognize
238 		 * localhost names as special and SHOULD always return the IP
239 		 * loopback address for address queries and negative responses
240 		 * for all other query types.  Name resolution APIs SHOULD NOT
241 		 * send queries for localhost names to their configured caching
242 		 * DNS server(s).
243 		 */
244 		if (as->as.ai.hostname == NULL || is_localhost) {
245 			for (family = iter_family(as, 1);
246 			    family != -1;
247 			    family = iter_family(as, 0)) {
248 				/*
249 				 * We could use statically built sockaddrs for
250 				 * those, rather than parsing over and over.
251 				 */
252 				if (family == PF_INET)
253 					str = (ai->ai_flags & AI_PASSIVE &&
254 					    !is_localhost) ? "0.0.0.0" :
255 					    "127.0.0.1";
256 				else /* PF_INET6 */
257 					str = (ai->ai_flags & AI_PASSIVE &&
258 					    !is_localhost) ? "::" : "::1";
259 				 /* This can't fail */
260 				_asr_sockaddr_from_str(&sa.sa, family, str);
261 				if ((r = addrinfo_add(as, &sa.sa, NULL))) {
262 					ar->ar_gai_errno = r;
263 					break;
264 				}
265 			}
266 			if (ar->ar_gai_errno == 0 && as->as_count == 0) {
267 				ar->ar_gai_errno = EAI_NODATA;
268 			}
269 			async_set_state(as, ASR_STATE_HALT);
270 			break;
271 		}
272 
273 		/* Try numeric addresses first */
274 		for (family = iter_family(as, 1);
275 		    family != -1;
276 		    family = iter_family(as, 0)) {
277 
278 			if (_asr_sockaddr_from_str(&sa.sa, family,
279 			    as->as.ai.hostname) == -1)
280 				continue;
281 
282 			if ((r = addrinfo_add(as, &sa.sa, NULL)))
283 				ar->ar_gai_errno = r;
284 			break;
285 		}
286 		if (ar->ar_gai_errno || as->as_count) {
287 			async_set_state(as, ASR_STATE_HALT);
288 			break;
289 		}
290 
291 		if (ai->ai_flags & AI_NUMERICHOST) {
292 			ar->ar_gai_errno = EAI_NONAME;
293 			async_set_state(as, ASR_STATE_HALT);
294 			break;
295 		}
296 
297 		/* make sure there are no funny characters in hostname */
298 		if (!hnok_lenient(as->as.ai.hostname)) {
299 			ar->ar_gai_errno = EAI_FAIL;
300 			async_set_state(as, ASR_STATE_HALT);
301 			break;
302 		}
303 
304 		async_set_state(as, ASR_STATE_NEXT_DB);
305 		break;
306 
307 	case ASR_STATE_NEXT_DB:
308 		if (_asr_iter_db(as) == -1) {
309 			async_set_state(as, ASR_STATE_NOT_FOUND);
310 			break;
311 		}
312 		as->as_family_idx = 0;
313 		async_set_state(as, ASR_STATE_SAME_DB);
314 		break;
315 
316 	case ASR_STATE_NEXT_FAMILY:
317 		as->as_family_idx += 1;
318 		if (as->as.ai.hints.ai_family != AF_UNSPEC ||
319 		    AS_FAMILY(as) == -1) {
320 			/* The family was specified, or we have tried all
321 			 * families with this DB.
322 			 */
323 			if (as->as_count) {
324 				ar->ar_gai_errno = 0;
325 				async_set_state(as, ASR_STATE_HALT);
326 			} else
327 				async_set_state(as, ASR_STATE_NEXT_DOMAIN);
328 			break;
329 		}
330 		async_set_state(as, ASR_STATE_SAME_DB);
331 		break;
332 
333 	case ASR_STATE_NEXT_DOMAIN:
334 		/* domain search is only for dns */
335 		if (AS_DB(as) != ASR_DB_DNS) {
336 			async_set_state(as, ASR_STATE_NEXT_DB);
337 			break;
338 		}
339 		as->as_family_idx = 0;
340 
341 		free(as->as.ai.fqdn);
342 		as->as.ai.fqdn = NULL;
343 		r = _asr_iter_domain(as, as->as.ai.hostname, fqdn, sizeof(fqdn));
344 		if (r == -1) {
345 			async_set_state(as, ASR_STATE_NEXT_DB);
346 			break;
347 		}
348 		if (r == 0) {
349 			ar->ar_gai_errno = EAI_FAIL;
350 			async_set_state(as, ASR_STATE_HALT);
351 			break;
352 		}
353 		as->as.ai.fqdn = strdup(fqdn);
354 		if (as->as.ai.fqdn == NULL) {
355 			ar->ar_gai_errno = EAI_MEMORY;
356 			async_set_state(as, ASR_STATE_HALT);
357 			break;
358 		}
359 
360 		async_set_state(as, ASR_STATE_SAME_DB);
361 		break;
362 
363 	case ASR_STATE_SAME_DB:
364 		/* query the current DB again */
365 		switch (AS_DB(as)) {
366 		case ASR_DB_DNS:
367 			if (as->as.ai.fqdn == NULL) {
368 				/* First try, initialize domain iteration */
369 				as->as_dom_flags = 0;
370 				as->as_dom_step = DOM_INIT;
371 				async_set_state(as, ASR_STATE_NEXT_DOMAIN);
372 				break;
373 			}
374 
375 			family = (as->as.ai.hints.ai_family == AF_UNSPEC) ?
376 			    AS_FAMILY(as) : as->as.ai.hints.ai_family;
377 
378 			if (family == AF_INET &&
379 			    as->as_flags & ASYNC_NO_INET) {
380 				async_set_state(as, ASR_STATE_NEXT_FAMILY);
381 				break;
382 			} else if (family == AF_INET6 &&
383 			    as->as_flags & ASYNC_NO_INET6) {
384 				async_set_state(as, ASR_STATE_NEXT_FAMILY);
385 				break;
386 			}
387 
388 			as->as_subq = _res_query_async_ctx(as->as.ai.fqdn,
389 			    C_IN, (family == AF_INET6) ? T_AAAA : T_A,
390 			    as->as_ctx);
391 
392 			if (as->as_subq == NULL) {
393 				if (errno == ENOMEM)
394 					ar->ar_gai_errno = EAI_MEMORY;
395 				else
396 					ar->ar_gai_errno = EAI_FAIL;
397 				async_set_state(as, ASR_STATE_HALT);
398 				break;
399 			}
400 			async_set_state(as, ASR_STATE_SUBQUERY);
401 			break;
402 
403 		case ASR_DB_FILE:
404 			f = fopen(_PATH_HOSTS, "re");
405 			if (f == NULL) {
406 				async_set_state(as, ASR_STATE_NEXT_DB);
407 				break;
408 			}
409 			family = (as->as.ai.hints.ai_family == AF_UNSPEC) ?
410 			    AS_FAMILY(as) : as->as.ai.hints.ai_family;
411 
412 			r = addrinfo_from_file(as, family, f);
413 			if (r == -1) {
414 				if (errno == ENOMEM)
415 					ar->ar_gai_errno = EAI_MEMORY;
416 				else
417 					ar->ar_gai_errno = EAI_FAIL;
418 				async_set_state(as, ASR_STATE_HALT);
419 			} else
420 				async_set_state(as, ASR_STATE_NEXT_FAMILY);
421 			fclose(f);
422 			break;
423 
424 		default:
425 			async_set_state(as, ASR_STATE_NEXT_DB);
426 		}
427 		break;
428 
429 	case ASR_STATE_SUBQUERY:
430 		if ((r = asr_run(as->as_subq, ar)) == ASYNC_COND)
431 			return (ASYNC_COND);
432 
433 		as->as_subq = NULL;
434 
435 		if (ar->ar_datalen == -1) {
436 			async_set_state(as, ASR_STATE_NEXT_FAMILY);
437 			break;
438 		}
439 
440 		r = addrinfo_from_pkt(as, ar->ar_data, ar->ar_datalen);
441 		if (r == -1) {
442 			if (errno == ENOMEM)
443 				ar->ar_gai_errno = EAI_MEMORY;
444 			else
445 				ar->ar_gai_errno = EAI_FAIL;
446 			async_set_state(as, ASR_STATE_HALT);
447 		} else
448 			async_set_state(as, ASR_STATE_NEXT_FAMILY);
449 		free(ar->ar_data);
450 		break;
451 
452 	case ASR_STATE_NOT_FOUND:
453 		/* No result found. Maybe we can try again. */
454 		if (as->as_flags & ASYNC_AGAIN)
455 			ar->ar_gai_errno = EAI_AGAIN;
456 		else
457 			ar->ar_gai_errno = EAI_NODATA;
458 		async_set_state(as, ASR_STATE_HALT);
459 		break;
460 
461 	case ASR_STATE_HALT:
462 		if (ar->ar_gai_errno == 0) {
463 			ar->ar_count = as->as_count;
464 			ar->ar_addrinfo = as->as.ai.aifirst;
465 			as->as.ai.aifirst = NULL;
466 		} else {
467 			ar->ar_count = 0;
468 			ar->ar_addrinfo = NULL;
469 		}
470 		return (ASYNC_DONE);
471 
472 	default:
473 		ar->ar_errno = EOPNOTSUPP;
474 		ar->ar_gai_errno = EAI_SYSTEM;
475 		async_set_state(as, ASR_STATE_HALT);
476 		break;
477 	}
478 	goto next;
479 }
480 
481 /*
482  * Retrieve the port number for the service name "servname" and
483  * the protocol "proto".
484  */
485 static int
486 get_port(const char *servname, const char *proto, int numonly)
487 {
488 	struct servent		se;
489 	struct servent_data	sed;
490 	int			port;
491 	const char		*e;
492 
493 	if (servname == NULL)
494 		return (0);
495 
496 	e = NULL;
497 	port = strtonum(servname, 0, USHRT_MAX, &e);
498 	if (e == NULL)
499 		return (port);
500 	if (errno == ERANGE)
501 		return (-2); /* invalid */
502 	if (numonly)
503 		return (-2);
504 
505 	port = -1;
506 	memset(&sed, 0, sizeof(sed));
507 	if (getservbyname_r(servname, proto, &se, &sed) != -1)
508 		port = ntohs(se.s_port);
509 	endservent_r(&sed);
510 
511 	return (port);
512 }
513 
514 /*
515  * Iterate over the address families that are to be queried. Use the
516  * list on the async context, unless a specific family was given in hints.
517  */
518 static int
519 iter_family(struct asr_query *as, int first)
520 {
521 	if (first) {
522 		as->as_family_idx = 0;
523 		if (as->as.ai.hints.ai_family != PF_UNSPEC)
524 			return as->as.ai.hints.ai_family;
525 		return AS_FAMILY(as);
526 	}
527 
528 	if (as->as.ai.hints.ai_family != PF_UNSPEC)
529 		return (-1);
530 
531 	as->as_family_idx++;
532 
533 	return AS_FAMILY(as);
534 }
535 
536 /*
537  * Use the sockaddr at "sa" to extend the result list on the "as" context,
538  * with the specified canonical name "cname". This function adds one
539  * entry per protocol/socktype match.
540  */
541 static int
542 addrinfo_add(struct asr_query *as, const struct sockaddr *sa, const char *cname)
543 {
544 	struct addrinfo		*ai;
545 	int			 i, port, proto;
546 
547 	for (i = 0; matches[i].family != -1; i++) {
548 		if (matches[i].family != sa->sa_family ||
549 		    !MATCH_SOCKTYPE(as->as.ai.hints.ai_socktype, i) ||
550 		    !MATCH_PROTO(as->as.ai.hints.ai_protocol, i))
551 			continue;
552 
553 		proto = as->as.ai.hints.ai_protocol;
554 		if (!proto)
555 			proto = matches[i].protocol;
556 
557 		if (proto == IPPROTO_TCP)
558 			port = as->as.ai.port_tcp;
559 		else if (proto == IPPROTO_UDP)
560 			port = as->as.ai.port_udp;
561 		else
562 			port = 0;
563 
564 		/* servname specified, but not defined for this protocol */
565 		if (port == -1)
566 			continue;
567 
568 		ai = calloc(1, sizeof(*ai) + sa->sa_len);
569 		if (ai == NULL)
570 			return (EAI_MEMORY);
571 		ai->ai_family = sa->sa_family;
572 		ai->ai_socktype = matches[i].socktype;
573 		ai->ai_protocol = proto;
574 		ai->ai_flags = as->as.ai.hints.ai_flags;
575 		ai->ai_addrlen = sa->sa_len;
576 		ai->ai_addr = (void *)(ai + 1);
577 		if (cname &&
578 		    as->as.ai.hints.ai_flags & (AI_CANONNAME | AI_FQDN)) {
579 			if ((ai->ai_canonname = strdup(cname)) == NULL) {
580 				free(ai);
581 				return (EAI_MEMORY);
582 			}
583 		}
584 		memmove(ai->ai_addr, sa, sa->sa_len);
585 		if (sa->sa_family == PF_INET)
586 			((struct sockaddr_in *)ai->ai_addr)->sin_port =
587 			    htons(port);
588 		else if (sa->sa_family == PF_INET6)
589 			((struct sockaddr_in6 *)ai->ai_addr)->sin6_port =
590 			    htons(port);
591 
592 		if (as->as.ai.aifirst == NULL)
593 			as->as.ai.aifirst = ai;
594 		if (as->as.ai.ailast)
595 			as->as.ai.ailast->ai_next = ai;
596 		as->as.ai.ailast = ai;
597 		as->as_count += 1;
598 	}
599 
600 	return (0);
601 }
602 
603 static int
604 addrinfo_from_file(struct asr_query *as, int family, FILE *f)
605 {
606 	char		*tokens[MAXTOKEN], *c, buf[BUFSIZ + 1];
607 	int		 n, i;
608 	union {
609 		struct sockaddr		sa;
610 		struct sockaddr_in	sain;
611 		struct sockaddr_in6	sain6;
612 	} u;
613 
614 	for (;;) {
615 		n = _asr_parse_namedb_line(f, tokens, MAXTOKEN, buf, sizeof(buf));
616 		if (n == -1)
617 			break; /* ignore errors reading the file */
618 
619 		for (i = 1; i < n; i++) {
620 			if (strcasecmp(as->as.ai.hostname, tokens[i]))
621 				continue;
622 			if (_asr_sockaddr_from_str(&u.sa, family, tokens[0]) == -1)
623 				continue;
624 			break;
625 		}
626 		if (i == n)
627 			continue;
628 
629 		if (as->as.ai.hints.ai_flags & (AI_CANONNAME | AI_FQDN))
630 			c = tokens[1];
631 		else
632 			c = NULL;
633 
634 		if (addrinfo_add(as, &u.sa, c))
635 			return (-1); /* errno set */
636 	}
637 	return (0);
638 }
639 
640 static int
641 addrinfo_from_pkt(struct asr_query *as, char *pkt, size_t pktlen)
642 {
643 	struct asr_unpack	 p;
644 	struct asr_dns_header	 h;
645 	struct asr_dns_query	 q;
646 	struct asr_dns_rr	 rr;
647 	int			 i;
648 	union {
649 		struct sockaddr		sa;
650 		struct sockaddr_in	sain;
651 		struct sockaddr_in6	sain6;
652 	} u;
653 	char		 buf[MAXDNAME], *c;
654 
655 	_asr_unpack_init(&p, pkt, pktlen);
656 	_asr_unpack_header(&p, &h);
657 	for (; h.qdcount; h.qdcount--)
658 		_asr_unpack_query(&p, &q);
659 
660 	for (i = 0; i < h.ancount; i++) {
661 		_asr_unpack_rr(&p, &rr);
662 		if (rr.rr_type != q.q_type ||
663 		    rr.rr_class != q.q_class)
664 			continue;
665 
666 		memset(&u, 0, sizeof u);
667 		if (rr.rr_type == T_A) {
668 			u.sain.sin_len = sizeof u.sain;
669 			u.sain.sin_family = AF_INET;
670 			u.sain.sin_addr = rr.rr.in_a.addr;
671 			u.sain.sin_port = 0;
672 		} else if (rr.rr_type == T_AAAA) {
673 			u.sain6.sin6_len = sizeof u.sain6;
674 			u.sain6.sin6_family = AF_INET6;
675 			u.sain6.sin6_addr = rr.rr.in_aaaa.addr6;
676 			u.sain6.sin6_port = 0;
677 		} else
678 			continue;
679 
680 		if (as->as.ai.hints.ai_flags & AI_CANONNAME) {
681 			_asr_strdname(rr.rr_dname, buf, sizeof buf);
682 			buf[strlen(buf) - 1] = '\0';
683 			c = res_hnok(buf) ? buf : NULL;
684 		} else if (as->as.ai.hints.ai_flags & AI_FQDN)
685 			c = as->as.ai.fqdn;
686 		else
687 			c = NULL;
688 
689 		if (addrinfo_add(as, &u.sa, c))
690 			return (-1); /* errno set */
691 	}
692 	return (0);
693 }
694 
695 static int
696 addrconfig_setup(struct asr_query *as)
697 {
698 	struct ifaddrs		*ifa, *ifa0;
699 	struct if_data		*ifa_data;
700 	struct sockaddr_in	*sinp;
701 	struct sockaddr_in6	*sin6p;
702 	int			 rtable, ifa_rtable = -1;
703 
704 	if (getifaddrs(&ifa0) == -1)
705 		return (-1);
706 
707 	rtable = getrtable();
708 
709 	as->as_flags |= ASYNC_NO_INET | ASYNC_NO_INET6;
710 
711 	for (ifa = ifa0; ifa != NULL; ifa = ifa->ifa_next) {
712 		if (ifa->ifa_addr == NULL)
713 			continue;
714 
715 		switch (ifa->ifa_addr->sa_family) {
716 		case PF_LINK:
717 			/* AF_LINK comes before inet / inet6 on an interface */
718 			ifa_data = (struct if_data *)ifa->ifa_data;
719 			ifa_rtable = ifa_data->ifi_rdomain;
720 			break;
721 		case PF_INET:
722 			if (ifa_rtable != rtable)
723 				continue;
724 
725 			sinp = (struct sockaddr_in *)ifa->ifa_addr;
726 
727 			if (sinp->sin_addr.s_addr == htonl(INADDR_LOOPBACK))
728 				continue;
729 
730 			as->as_flags &= ~ASYNC_NO_INET;
731 			break;
732 		case PF_INET6:
733 			if (ifa_rtable != rtable)
734 				continue;
735 
736 			sin6p = (struct sockaddr_in6 *)ifa->ifa_addr;
737 
738 			if (IN6_IS_ADDR_LOOPBACK(&sin6p->sin6_addr))
739 				continue;
740 
741 			if (IN6_IS_ADDR_LINKLOCAL(&sin6p->sin6_addr))
742 				continue;
743 
744 			as->as_flags &= ~ASYNC_NO_INET6;
745 			break;
746 		}
747 	}
748 
749 	freeifaddrs(ifa0);
750 
751 	return (0);
752 }
753