1
/* $NetBSD: res_query.c,v 1.7 2006/01/24 17:41:25 christos Exp $ */
4
* Copyright (c) 1988, 1993
5
* The Regents of the University of California. All rights reserved.
7
* Redistribution and use in source and binary forms, with or without
8
* modification, are permitted provided that the following conditions
10
* 1. Redistributions of source code must retain the above copyright
11
* notice, this list of conditions and the following disclaimer.
12
* 2. Redistributions in binary form must reproduce the above copyright
13
* notice, this list of conditions and the following disclaimer in the
14
* documentation and/or other materials provided with the distribution.
15
* 3. All advertising materials mentioning features or use of this software
16
* must display the following acknowledgement:
17
* This product includes software developed by the University of
18
* California, Berkeley and its contributors.
19
* 4. Neither the name of the University nor the names of its contributors
20
* may be used to endorse or promote products derived from this software
21
* without specific prior written permission.
23
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
37
* Portions Copyright (c) 1993 by Digital Equipment Corporation.
39
* Permission to use, copy, modify, and distribute this software for any
40
* purpose with or without fee is hereby granted, provided that the above
41
* copyright notice and this permission notice appear in all copies, and that
42
* the name of Digital Equipment Corporation not be used in advertising or
43
* publicity pertaining to distribution of the document or software without
44
* specific, written prior permission.
46
* THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
47
* WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
48
* OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL DIGITAL EQUIPMENT
49
* CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
50
* DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
51
* PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
52
* ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
57
* Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
58
* Portions Copyright (c) 1996-1999 by Internet Software Consortium.
60
* Permission to use, copy, modify, and distribute this software for any
61
* purpose with or without fee is hereby granted, provided that the above
62
* copyright notice and this permission notice appear in all copies.
64
* THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
65
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
66
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR
67
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
68
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
69
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
70
* OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
73
#include <sys/cdefs.h>
74
#if defined(LIBC_SCCS) && !defined(lint)
76
static const char sccsid[] = "@(#)res_query.c 8.1 (Berkeley) 6/4/93";
77
static const char rcsid[] = "Id: res_query.c,v 1.2.2.3.4.2 2004/03/16 12:34:19 marka Exp";
79
__RCSID("$NetBSD: res_query.c,v 1.7 2006/01/24 17:41:25 christos Exp $");
81
#endif /* LIBC_SCCS and not lint */
85
#include <sys/types.h>
86
#include <sys/param.h>
87
#include <netinet/in.h>
88
#include <arpa/inet.h>
89
#include "arpa_nameser.h"
93
#ifdef ANDROID_CHANGES
94
#include "resolv_private.h"
103
#define DISABLE_HOST_ALIAS 1
105
/* Options. Leave them on. */
111
#define MAXPACKET PACKETSZ
113
#define MAXPACKET 1024
117
* Formulate a normal query, send, and await answer.
118
* Returned answer is placed in supplied buffer "answer".
119
* Perform preliminary check of answer, returning success only
120
* if no error is indicated and the answer count is nonzero.
121
* Return the size of the response on success, -1 on error.
122
* Error number is left in H_ERRNO.
124
* Caller must parse answer and determine whether it answers the question.
127
res_nquery(res_state statp,
128
const char *name, /* domain name */
129
int class, int type, /* class and type of query */
130
u_char *answer, /* buffer to put answer */
131
int anslen) /* size of answer buffer */
133
u_char buf[MAXPACKET];
134
HEADER *hp = (HEADER *)(void *)answer;
138
oflags = statp->_flags;
141
hp->rcode = NOERROR; /* default */
144
if (statp->options & RES_DEBUG)
145
printf(";; res_query(%s, %d, %d)\n", name, class, type);
148
n = res_nmkquery(statp, QUERY, name, class, type, NULL, 0, NULL,
151
if (n > 0 && (statp->_flags & RES_F_EDNS0ERR) == 0 &&
152
(statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0U)
153
n = res_nopt(statp, n, buf, sizeof(buf), anslen);
157
if (statp->options & RES_DEBUG)
158
printf(";; res_query: mkquery failed\n");
160
RES_SET_H_ERRNO(statp, NO_RECOVERY);
163
n = res_nsend(statp, buf, n, answer, anslen);
166
/* if the query choked with EDNS0, retry without EDNS0 */
167
if ((statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0U &&
168
((oflags ^ statp->_flags) & RES_F_EDNS0ERR) != 0) {
169
statp->_flags |= RES_F_EDNS0ERR;
170
if (statp->options & RES_DEBUG)
171
printf(";; res_nquery: retry without EDNS0\n");
176
if (statp->options & RES_DEBUG)
177
printf(";; res_query: send error\n");
179
RES_SET_H_ERRNO(statp, TRY_AGAIN);
183
if (hp->rcode != NOERROR || ntohs(hp->ancount) == 0) {
185
if (statp->options & RES_DEBUG)
186
printf(";; rcode = (%s), counts = an:%d ns:%d ar:%d\n",
194
RES_SET_H_ERRNO(statp, HOST_NOT_FOUND);
197
RES_SET_H_ERRNO(statp, TRY_AGAIN);
200
RES_SET_H_ERRNO(statp, NO_DATA);
206
RES_SET_H_ERRNO(statp, NO_RECOVERY);
215
* Formulate a normal query, send, and retrieve answer in supplied buffer.
216
* Return the size of the response on success, -1 on error.
217
* If enabled, implement search rules until answer or unrecoverable failure
218
* is detected. Error code, if any, is left in H_ERRNO.
221
res_nsearch(res_state statp,
222
const char *name, /* domain name */
223
int class, int type, /* class and type of query */
224
u_char *answer, /* buffer to put answer */
225
int anslen) /* size of answer */
227
const char *cp, * const *domain;
228
HEADER *hp = (HEADER *)(void *)answer;
229
char tmp[NS_MAXDNAME];
231
int trailing_dot, ret, saved_herrno;
232
int got_nodata = 0, got_servfail = 0, root_on_list = 0;
237
RES_SET_H_ERRNO(statp, HOST_NOT_FOUND); /* True if we never query. */
240
for (cp = name; *cp != '\0'; cp++)
241
dots += (*cp == '.');
243
if (cp > name && *--cp == '.')
246
/* If there aren't any dots, it could be a user-level alias. */
247
if (!dots && (cp = res_hostalias(statp, name, tmp, sizeof tmp))!= NULL)
248
return (res_nquery(statp, cp, class, type, answer, anslen));
251
* If there are enough dots in the name, let's just give it a
252
* try 'as is'. The threshold can be set with the "ndots" option.
253
* Also, query 'as is', if there is a trailing dot in the name.
256
if (dots >= statp->ndots || trailing_dot) {
257
ret = res_nquerydomain(statp, name, NULL, class, type,
259
if (ret > 0 || trailing_dot)
261
saved_herrno = statp->res_h_errno;
266
* We do at least one level of search if
267
* - there is no dot and RES_DEFNAME is set, or
268
* - there is at least one dot, there is no trailing dot,
269
* and RES_DNSRCH is set.
271
if ((!dots && (statp->options & RES_DEFNAMES) != 0U) ||
272
(dots && !trailing_dot && (statp->options & RES_DNSRCH) != 0U)) {
275
for (domain = (const char * const *)statp->dnsrch;
280
if (domain[0][0] == '\0' ||
281
(domain[0][0] == '.' && domain[0][1] == '\0'))
284
ret = res_nquerydomain(statp, name, *domain,
291
* If no server present, give up.
292
* If name isn't found in this domain,
293
* keep trying higher domains in the search list
294
* (if that's enabled).
295
* On a NO_DATA error, keep trying, otherwise
296
* a wildcard entry of another type could keep us
297
* from finding this entry higher in the domain.
298
* If we get some other error (negative answer or
299
* server failure), then stop searching up,
300
* but try the input name below in case it's
303
if (errno == ECONNREFUSED) {
304
RES_SET_H_ERRNO(statp, TRY_AGAIN);
308
switch (statp->res_h_errno) {
316
if (hp->rcode == SERVFAIL) {
317
/* try next search element, if any */
323
/* anything else implies that we're done */
327
/* if we got here for some reason other than DNSRCH,
328
* we only wanted one iteration of the loop, so stop.
330
if ((statp->options & RES_DNSRCH) == 0U)
336
* If the query has not already been tried as is then try it
337
* unless RES_NOTLDQUERY is set and there were no dots.
339
if ((dots || !searched || (statp->options & RES_NOTLDQUERY) == 0U) &&
340
!(tried_as_is || root_on_list)) {
341
ret = res_nquerydomain(statp, name, NULL, class, type,
347
/* if we got here, we didn't satisfy the search.
348
* if we did an initial full query, return that query's H_ERRNO
349
* (note that we wouldn't be here if that query had succeeded).
350
* else if we ever got a nodata, send that back as the reason.
351
* else send back meaningless H_ERRNO, that being the one from
352
* the last DNSRCH we did.
354
if (saved_herrno != -1)
355
RES_SET_H_ERRNO(statp, saved_herrno);
357
RES_SET_H_ERRNO(statp, NO_DATA);
358
else if (got_servfail)
359
RES_SET_H_ERRNO(statp, TRY_AGAIN);
364
* Perform a call on res_query on the concatenation of name and domain,
365
* removing a trailing dot from name if domain is NULL.
368
res_nquerydomain(res_state statp,
371
int class, int type, /* class and type of query */
372
u_char *answer, /* buffer to put answer */
373
int anslen) /* size of answer */
376
const char *longname = nbuf;
380
if (statp->options & RES_DEBUG)
381
printf(";; res_nquerydomain(%s, %s, %d, %d)\n",
382
name, domain?domain:"<Nil>", class, type);
384
if (domain == NULL) {
386
* Check for trailing '.';
387
* copy without '.' if present.
391
RES_SET_H_ERRNO(statp, NO_RECOVERY);
395
if (n >= 0 && name[n] == '.') {
396
strncpy(nbuf, name, (size_t)n);
403
if (n + d + 1 >= MAXDNAME) {
404
RES_SET_H_ERRNO(statp, NO_RECOVERY);
407
sprintf(nbuf, "%s.%s", name, domain);
409
return (res_nquery(statp, longname, class, type, answer, anslen));
413
res_hostalias(const res_state statp, const char *name, char *dst, size_t siz) {