2 * Copyright (c) 1988, 1993
3 * The Regents of the University of California. All rights reserved.
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 4. Neither the name of the University nor the names of its contributors
14 * may be used to endorse or promote products derived from this software
15 * without specific prior written permission.
17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * Portions Copyright (c) 1993 by Digital Equipment Corporation.
33 * Permission to use, copy, modify, and distribute this software for any
34 * purpose with or without fee is hereby granted, provided that the above
35 * copyright notice and this permission notice appear in all copies, and that
36 * the name of Digital Equipment Corporation not be used in advertising or
37 * publicity pertaining to distribution of the document or software without
38 * specific, written prior permission.
40 * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
41 * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
42 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL DIGITAL EQUIPMENT
43 * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
44 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
45 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
46 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
51 * Portions Copyright (c) 1996-1999 by Internet Software Consortium.
53 * Permission to use, copy, modify, and distribute this software for any
54 * purpose with or without fee is hereby granted, provided that the above
55 * copyright notice and this permission notice appear in all copies.
57 * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
58 * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
59 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
60 * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
61 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
62 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
63 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
68 #include <sys/types.h>
69 #include <sys/param.h>
70 #include <netinet/in.h>
71 #include <arpa/inet.h>
72 #include <arpa/nameser.h>
77 #include <resolv/resolv-internal.h>
78 #include <resolv/resolv_context.h>
82 #include <shlib-compat.h>
83 #include <scratch_buffer.h>
87 #define MAXPACKET PACKETSZ
89 #define MAXPACKET 65536
92 #define QUERYSIZE (HFIXEDSZ + QFIXEDSZ + MAXCDNAME + 1)
95 __res_context_querydomain (struct resolv_context
*,
96 const char *name
, const char *domain
,
97 int class, int type
, unsigned char *answer
, int anslen
,
98 unsigned char **answerp
, unsigned char **answerp2
, int *nanswerp2
,
99 int *resplen2
, int *answerp2_malloced
);
101 /* Formulate a normal query, send, and await answer. Returned answer
102 is placed in supplied buffer ANSWER. Perform preliminary check of
103 answer, returning success only if no error is indicated and the
104 answer count is nonzero. Return the size of the response on
105 success, -1 on error. Error number is left in h_errno.
107 Caller must parse answer and determine whether it answers the
110 __res_context_query (struct resolv_context
*ctx
, const char *name
,
112 unsigned char *answer
, int anslen
,
113 unsigned char **answerp
, unsigned char **answerp2
,
114 int *nanswerp2
, int *resplen2
, int *answerp2_malloced
)
116 struct __res_state
*statp
= ctx
->resp
;
117 UHEADER
*hp
= (UHEADER
*) answer
;
120 bool retried
= false;
122 /* It requires 2 times QUERYSIZE for type == T_QUERY_A_AND_AAAA. */
123 struct scratch_buffer buf
;
124 scratch_buffer_init (&buf
);
125 _Static_assert (2 * QUERYSIZE
<= sizeof (buf
.__space
.__c
),
126 "scratch_buffer too small");
127 u_char
*query1
= buf
.data
;
129 u_char
*query2
= NULL
;
133 hp
->rcode
= NOERROR
; /* default */
135 if (type
== T_QUERY_A_AND_AAAA
)
137 n
= __res_context_mkquery (ctx
, QUERY
, name
, class, T_A
, NULL
,
141 if ((statp
->options
& (RES_USE_EDNS0
|RES_USE_DNSSEC
)) != 0)
143 /* Use RESOLV_EDNS_BUFFER_SIZE because the receive
144 buffer can be reallocated. */
145 n
= __res_nopt (ctx
, n
, query1
, buf
.length
,
146 RESOLV_EDNS_BUFFER_SIZE
);
152 query2
= buf
.data
+ n
;
153 n
= __res_context_mkquery (ctx
, QUERY
, name
, class, T_AAAA
,
154 NULL
, query2
, buf
.length
- n
);
156 && (statp
->options
& (RES_USE_EDNS0
|RES_USE_DNSSEC
)) != 0)
157 /* Use RESOLV_EDNS_BUFFER_SIZE because the receive
158 buffer can be reallocated. */
159 n
= __res_nopt (ctx
, n
, query2
, buf
.length
,
160 RESOLV_EDNS_BUFFER_SIZE
);
168 n
= __res_context_mkquery (ctx
, QUERY
, name
, class, type
, NULL
,
172 && (statp
->options
& (RES_USE_EDNS0
|RES_USE_DNSSEC
)) != 0)
174 /* Use RESOLV_EDNS_BUFFER_SIZE if the receive buffer
175 can be reallocated. */
180 advertise
= RESOLV_EDNS_BUFFER_SIZE
;
181 n
= __res_nopt (ctx
, n
, query1
, buf
.length
, advertise
);
187 if (__glibc_unlikely (n
<= 0) && !retried
) {
188 /* Retry just in case res_nmkquery failed because of too
189 short buffer. Shouldn't happen. */
190 if (scratch_buffer_set_array_size (&buf
,
191 (type
== T_QUERY_A_AND_AAAA
)
199 if (__glibc_unlikely (n
<= 0)) {
200 RES_SET_H_ERRNO(statp
, NO_RECOVERY
);
201 scratch_buffer_free (&buf
);
205 /* Suppress AAAA lookups if required. __res_handle_no_aaaa
206 checks RES_NOAAAA first, so avoids parsing the
207 just-generated query packet in most cases. nss_dns avoids
208 using T_QUERY_A_AND_AAAA in RES_NOAAAA mode, so there is no
209 need to handle it here. */
210 if (type
== T_AAAA
&& __res_handle_no_aaaa (ctx
, query1
, nquery1
,
212 /* There must be no second query for AAAA queries. The code
213 below is still needed to translate NODATA responses. */
214 assert (query2
== NULL
);
217 assert (answerp
== NULL
|| (void *) *answerp
== (void *) answer
);
218 n
= __res_context_send (ctx
, query1
, nquery1
, query2
, nquery2
,
220 answerp
, answerp2
, nanswerp2
, resplen2
,
224 scratch_buffer_free (&buf
);
226 RES_SET_H_ERRNO(statp
, TRY_AGAIN
);
231 /* __res_context_send might have reallocated the buffer. */
232 hp
= (UHEADER
*) *answerp
;
234 /* We simplify the following tests by assigning HP to HP2 or
235 vice versa. It is easy to verify that this is the same as
236 ignoring all tests of HP or HP2. */
237 if (answerp2
== NULL
|| *resplen2
< (int) sizeof (HEADER
))
243 hp2
= (UHEADER
*) *answerp2
;
244 if (n
< (int) sizeof (HEADER
))
250 /* Make sure both hp and hp2 are defined */
251 assert((hp
!= NULL
) && (hp2
!= NULL
));
253 if ((hp
->rcode
!= NOERROR
|| ntohs(hp
->ancount
) == 0)
254 && (hp2
->rcode
!= NOERROR
|| ntohs(hp2
->ancount
) == 0)) {
255 switch (hp
->rcode
== NOERROR
? hp2
->rcode
: hp
->rcode
) {
257 if ((hp
->rcode
== NOERROR
&& ntohs (hp
->ancount
) != 0)
258 || (hp2
->rcode
== NOERROR
259 && ntohs (hp2
->ancount
) != 0))
261 RES_SET_H_ERRNO(statp
, HOST_NOT_FOUND
);
264 RES_SET_H_ERRNO(statp
, TRY_AGAIN
);
267 if (ntohs (hp
->ancount
) != 0
268 || ntohs (hp2
->ancount
) != 0)
270 RES_SET_H_ERRNO(statp
, NO_DATA
);
274 /* Servers must not reply to AAAA queries with
275 NOTIMP etc but some of them do. */
276 if ((hp
->rcode
== NOERROR
&& ntohs (hp
->ancount
) != 0)
277 || (hp2
->rcode
== NOERROR
278 && ntohs (hp2
->ancount
) != 0))
283 RES_SET_H_ERRNO(statp
, NO_RECOVERY
);
291 libc_hidden_def (__res_context_query
)
293 /* Common part of res_nquery and res_query. */
295 context_query_common (struct resolv_context
*ctx
,
296 const char *name
, int class, int type
,
297 unsigned char *answer
, int anslen
)
301 RES_SET_H_ERRNO (&_res
, NETDB_INTERNAL
);
304 int result
= __res_context_query (ctx
, name
, class, type
, answer
, anslen
,
305 NULL
, NULL
, NULL
, NULL
, NULL
);
306 __resolv_context_put (ctx
);
311 ___res_nquery (res_state statp
,
312 const char *name
, /* Domain name. */
313 int class, int type
, /* Class and type of query. */
314 unsigned char *answer
, /* Buffer to put answer. */
315 int anslen
) /* Size of answer buffer. */
317 return context_query_common
318 (__resolv_context_get_override (statp
), name
, class, type
, answer
, anslen
);
320 versioned_symbol (libc
, ___res_nquery
, res_nquery
, GLIBC_2_34
);
321 #if OTHER_SHLIB_COMPAT (libresolv, GLIBC_2_2, GLIBC_2_34)
322 compat_symbol (libresolv
, ___res_nquery
, __res_nquery
, GLIBC_2_2
);
326 ___res_query (const char *name
, int class, int type
,
327 unsigned char *answer
, int anslen
)
329 return context_query_common
330 (__resolv_context_get (), name
, class, type
, answer
, anslen
);
332 versioned_symbol (libc
, ___res_query
, res_query
, GLIBC_2_34
);
333 #if OTHER_SHLIB_COMPAT (libresolv, GLIBC_2_0, GLIBC_2_2)
334 compat_symbol (libresolv
, ___res_query
, res_query
, GLIBC_2_0
);
336 #if OTHER_SHLIB_COMPAT (libresolv, GLIBC_2_2, GLIBC_2_34)
337 compat_symbol (libresolv
, ___res_query
, __res_query
, GLIBC_2_2
);
340 /* Formulate a normal query, send, and retrieve answer in supplied
341 buffer. Return the size of the response on success, -1 on error.
342 If enabled, implement search rules until answer or unrecoverable
343 failure is detected. Error code, if any, is left in h_errno. */
345 __res_context_search (struct resolv_context
*ctx
,
346 const char *name
, int class, int type
,
347 unsigned char *answer
, int anslen
,
348 unsigned char **answerp
, unsigned char **answerp2
,
349 int *nanswerp2
, int *resplen2
, int *answerp2_malloced
)
351 struct __res_state
*statp
= ctx
->resp
;
353 UHEADER
*hp
= (UHEADER
*) answer
;
354 char tmp
[NS_MAXDNAME
];
356 int trailing_dot
, ret
, saved_herrno
;
357 int got_nodata
= 0, got_servfail
= 0, root_on_list
= 0;
362 RES_SET_H_ERRNO(statp
, HOST_NOT_FOUND
); /* True if we never query. */
365 for (cp
= name
; *cp
!= '\0'; cp
++)
366 dots
+= (*cp
== '.');
368 if (cp
> name
&& *--cp
== '.')
371 /* If there aren't any dots, it could be a user-level alias. */
372 if (!dots
&& (cp
= __res_context_hostalias
373 (ctx
, name
, tmp
, sizeof tmp
))!= NULL
)
374 return __res_context_query (ctx
, cp
, class, type
, answer
,
375 anslen
, answerp
, answerp2
,
376 nanswerp2
, resplen2
, answerp2_malloced
);
379 * If there are enough dots in the name, let's just give it a
380 * try 'as is'. The threshold can be set with the "ndots" option.
381 * Also, query 'as is', if there is a trailing dot in the name.
384 if (dots
>= statp
->ndots
|| trailing_dot
) {
385 ret
= __res_context_querydomain (ctx
, name
, NULL
, class, type
,
386 answer
, anslen
, answerp
,
387 answerp2
, nanswerp2
, resplen2
,
389 if (ret
> 0 || trailing_dot
390 /* If the second response is valid then we use that. */
391 || (ret
== 0 && resplen2
!= NULL
&& *resplen2
> 0))
393 saved_herrno
= h_errno
;
395 if (answerp
&& *answerp
!= answer
) {
399 if (answerp2
&& *answerp2_malloced
)
404 *answerp2_malloced
= 0;
409 * We do at least one level of search if
410 * - there is no dot and RES_DEFNAME is set, or
411 * - there is at least one dot, there is no trailing dot,
412 * and RES_DNSRCH is set.
414 if ((!dots
&& (statp
->options
& RES_DEFNAMES
) != 0) ||
415 (dots
&& !trailing_dot
&& (statp
->options
& RES_DNSRCH
) != 0)) {
418 for (size_t domain_index
= 0; !done
; ++domain_index
) {
419 const char *dname
= __resolv_context_search_list
425 /* __res_context_querydoman concatenates name
426 with dname with a "." in between. If we
427 pass it in dname the "." we got from the
428 configured default search path, we'll end
429 up with "name..", which won't resolve.
430 OTOH, passing it "" will result in "name.",
431 which has the intended effect for both
432 possible representations of the root
436 if (dname
[0] == '\0')
439 ret
= __res_context_querydomain
440 (ctx
, name
, dname
, class, type
,
441 answer
, anslen
, answerp
, answerp2
, nanswerp2
,
442 resplen2
, answerp2_malloced
);
443 if (ret
> 0 || (ret
== 0 && resplen2
!= NULL
447 if (answerp
&& *answerp
!= answer
) {
451 if (answerp2
&& *answerp2_malloced
)
456 *answerp2_malloced
= 0;
460 * If no server present, give up.
461 * If name isn't found in this domain,
462 * keep trying higher domains in the search list
463 * (if that's enabled).
464 * On a NO_DATA error, keep trying, otherwise
465 * a wildcard entry of another type could keep us
466 * from finding this entry higher in the domain.
467 * If we get some other error (negative answer or
468 * server failure), then stop searching up,
469 * but try the input name below in case it's
472 if (errno
== ECONNREFUSED
) {
473 RES_SET_H_ERRNO(statp
, TRY_AGAIN
);
477 switch (statp
->res_h_errno
) {
485 if (hp
->rcode
== SERVFAIL
) {
486 /* try next search element, if any */
492 /* anything else implies that we're done */
496 /* if we got here for some reason other than DNSRCH,
497 * we only wanted one iteration of the loop, so stop.
499 if ((statp
->options
& RES_DNSRCH
) == 0)
505 * If the query has not already been tried as is then try it
506 * unless RES_NOTLDQUERY is set and there were no dots.
508 if ((dots
|| !searched
|| (statp
->options
& RES_NOTLDQUERY
) == 0)
509 && !(tried_as_is
|| root_on_list
)) {
510 ret
= __res_context_querydomain
511 (ctx
, name
, NULL
, class, type
,
512 answer
, anslen
, answerp
, answerp2
, nanswerp2
,
513 resplen2
, answerp2_malloced
);
514 if (ret
> 0 || (ret
== 0 && resplen2
!= NULL
519 /* if we got here, we didn't satisfy the search.
520 * if we did an initial full query, return that query's H_ERRNO
521 * (note that we wouldn't be here if that query had succeeded).
522 * else if we ever got a nodata, send that back as the reason.
523 * else send back meaningless H_ERRNO, that being the one from
524 * the last DNSRCH we did.
526 if (answerp2
&& *answerp2_malloced
)
531 *answerp2_malloced
= 0;
533 if (saved_herrno
!= -1)
534 RES_SET_H_ERRNO(statp
, saved_herrno
);
536 RES_SET_H_ERRNO(statp
, NO_DATA
);
537 else if (got_servfail
)
538 RES_SET_H_ERRNO(statp
, TRY_AGAIN
);
541 libc_hidden_def (__res_context_search
)
543 /* Common part of res_nsearch and res_search. */
545 context_search_common (struct resolv_context
*ctx
,
546 const char *name
, int class, int type
,
547 unsigned char *answer
, int anslen
)
551 RES_SET_H_ERRNO (&_res
, NETDB_INTERNAL
);
554 int result
= __res_context_search (ctx
, name
, class, type
, answer
, anslen
,
555 NULL
, NULL
, NULL
, NULL
, NULL
);
556 __resolv_context_put (ctx
);
561 ___res_nsearch (res_state statp
,
562 const char *name
, /* Domain name. */
563 int class, int type
, /* Class and type of query. */
564 unsigned char *answer
, /* Buffer to put answer. */
565 int anslen
) /* Size of answer. */
567 return context_search_common
568 (__resolv_context_get_override (statp
), name
, class, type
, answer
, anslen
);
570 versioned_symbol (libc
, ___res_nsearch
, res_nsearch
, GLIBC_2_34
);
571 #if OTHER_SHLIB_COMPAT (libresolv, GLIBC_2_2, GLIBC_2_34)
572 compat_symbol (libresolv
, ___res_nsearch
, __res_nsearch
, GLIBC_2_2
);
576 ___res_search (const char *name
, int class, int type
,
577 unsigned char *answer
, int anslen
)
579 return context_search_common
580 (__resolv_context_get (), name
, class, type
, answer
, anslen
);
582 versioned_symbol (libc
, ___res_search
, res_search
, GLIBC_2_34
);
583 #if OTHER_SHLIB_COMPAT (libresolv, GLIBC_2_0, GLIBC_2_2)
584 compat_symbol (libresolv
, ___res_search
, res_search
, GLIBC_2_0
);
586 #if OTHER_SHLIB_COMPAT (libresolv, GLIBC_2_2, GLIBC_2_34)
587 compat_symbol (libresolv
, ___res_search
, __res_search
, GLIBC_2_2
);
590 /* Perform a call on res_query on the concatenation of name and
593 __res_context_querydomain (struct resolv_context
*ctx
,
594 const char *name
, const char *domain
,
596 unsigned char *answer
, int anslen
,
597 unsigned char **answerp
, unsigned char **answerp2
,
598 int *nanswerp2
, int *resplen2
,
599 int *answerp2_malloced
)
601 struct __res_state
*statp
= ctx
->resp
;
603 const char *longname
= nbuf
;
606 if (domain
== NULL
) {
609 /* Decrement N prior to checking it against MAXDNAME
610 so that we detect a wrap to SIZE_MAX and return
611 a reasonable error. */
613 if (n
>= MAXDNAME
- 1) {
614 RES_SET_H_ERRNO(statp
, NO_RECOVERY
);
621 if (n
+ d
+ 1 >= MAXDNAME
) {
622 RES_SET_H_ERRNO(statp
, NO_RECOVERY
);
625 char *p
= __stpcpy (nbuf
, name
);
629 return __res_context_query (ctx
, longname
, class, type
, answer
,
630 anslen
, answerp
, answerp2
, nanswerp2
,
631 resplen2
, answerp2_malloced
);
634 /* Common part of res_nquerydomain and res_querydomain. */
636 context_querydomain_common (struct resolv_context
*ctx
,
637 const char *name
, const char *domain
,
639 unsigned char *answer
, int anslen
)
643 RES_SET_H_ERRNO (&_res
, NETDB_INTERNAL
);
646 int result
= __res_context_querydomain (ctx
, name
, domain
, class, type
,
648 NULL
, NULL
, NULL
, NULL
, NULL
);
649 __resolv_context_put (ctx
);
654 ___res_nquerydomain (res_state statp
,
657 int class, int type
, /* Class and type of query. */
658 unsigned char *answer
, /* Buffer to put answer. */
659 int anslen
) /* Size of answer. */
661 return context_querydomain_common
662 (__resolv_context_get_override (statp
),
663 name
, domain
, class, type
, answer
, anslen
);
665 versioned_symbol (libc
, ___res_nquerydomain
, res_nquerydomain
, GLIBC_2_34
);
666 #if OTHER_SHLIB_COMPAT (libresolv, GLIBC_2_2, GLIBC_2_34)
667 compat_symbol (libresolv
, ___res_nquerydomain
, __res_nquerydomain
, GLIBC_2_2
);
671 ___res_querydomain (const char *name
, const char *domain
, int class, int type
,
672 unsigned char *answer
, int anslen
)
674 return context_querydomain_common
675 (__resolv_context_get (), name
, domain
, class, type
, answer
, anslen
);
677 versioned_symbol (libc
, ___res_querydomain
, res_querydomain
, GLIBC_2_34
);
678 #if OTHER_SHLIB_COMPAT (libresolv, GLIBC_2_0, GLIBC_2_2)
679 compat_symbol (libresolv
, ___res_querydomain
, res_querydomain
, GLIBC_2_0
);
681 #if OTHER_SHLIB_COMPAT (libresolv, GLIBC_2_2, GLIBC_2_34)
682 compat_symbol (libresolv
, ___res_querydomain
, __res_querydomain
, GLIBC_2_2
);