1 /* $NetBSD: res_query.c,v 1.7 2006/01/24 17:41:25 christos Exp $ */
2
3 /*
4 * Copyright (c) 1988, 1993
5 * The Regents of the University of California. All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
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.
22 *
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
33 * SUCH DAMAGE.
34 */
35
36 /*
37 * Portions Copyright (c) 1993 by Digital Equipment Corporation.
38 *
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.
45 *
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
53 * SOFTWARE.
54 */
55
56 /*
57 * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
58 * Portions Copyright (c) 1996-1999 by Internet Software Consortium.
59 *
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.
63 *
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.
71 */
72
73 #include <sys/cdefs.h>
74 #if defined(LIBC_SCCS) && !defined(lint)
75 #ifdef notdef
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";
78 #else
79 __RCSID("$NetBSD: res_query.c,v 1.7 2006/01/24 17:41:25 christos Exp $");
80 #endif
81 #endif /* LIBC_SCCS and not lint */
82
83
84
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>
90 #include <ctype.h>
91 #include <errno.h>
92 #include <netdb.h>
93 #ifdef ANDROID_CHANGES
94 #include "resolv_cache.h"
95 #include "resolv_private.h"
96 #else
97 #include <resolv.h>
98 #endif
99 #include <stdio.h>
100 #include <stdlib.h>
101 #include <unistd.h>
102 #include <string.h>
103
104 #define DISABLE_HOST_ALIAS 1
105
106 /* Options. Leave them on. */
107 #ifndef DEBUG
108 #define DEBUG
109 #endif
110
111 #if PACKETSZ > 1024
112 #define MAXPACKET PACKETSZ
113 #else
114 #define MAXPACKET 1024
115 #endif
116
117 /*
118 * Formulate a normal query, send, and await answer.
119 * Returned answer is placed in supplied buffer "answer".
120 * Perform preliminary check of answer, returning success only
121 * if no error is indicated and the answer count is nonzero.
122 * Return the size of the response on success, -1 on error.
123 * Error number is left in H_ERRNO.
124 *
125 * Caller must parse answer and determine whether it answers the question.
126 */
127 int
res_nquery(res_state statp,const char * name,int class,int type,u_char * answer,int anslen)128 res_nquery(res_state statp,
129 const char *name, /* domain name */
130 int class, int type, /* class and type of query */
131 u_char *answer, /* buffer to put answer */
132 int anslen) /* size of answer buffer */
133 {
134 u_char buf[MAXPACKET];
135 HEADER *hp = (HEADER *)(void *)answer;
136 int n;
137 u_int oflags;
138
139 oflags = statp->_flags;
140
141 again:
142 hp->rcode = NOERROR; /* default */
143
144 #ifdef DEBUG
145 if (statp->options & RES_DEBUG)
146 printf(";; res_query(%s, %d, %d)\n", name, class, type);
147 #endif
148
149 n = res_nmkquery(statp, QUERY, name, class, type, NULL, 0, NULL,
150 buf, sizeof(buf));
151 #ifdef RES_USE_EDNS0
152 if (n > 0 && (statp->_flags & RES_F_EDNS0ERR) == 0 &&
153 (statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0U)
154 n = res_nopt(statp, n, buf, sizeof(buf), anslen);
155 #endif
156 if (n <= 0) {
157 #ifdef DEBUG
158 if (statp->options & RES_DEBUG)
159 printf(";; res_query: mkquery failed\n");
160 #endif
161 RES_SET_H_ERRNO(statp, NO_RECOVERY);
162 return (n);
163 }
164 n = res_nsend(statp, buf, n, answer, anslen);
165 if (n < 0) {
166 #ifdef RES_USE_EDNS0
167 /* if the query choked with EDNS0, retry without EDNS0 */
168 if ((statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0U &&
169 ((oflags ^ statp->_flags) & RES_F_EDNS0ERR) != 0) {
170 statp->_flags |= RES_F_EDNS0ERR;
171 if (statp->options & RES_DEBUG)
172 printf(";; res_nquery: retry without EDNS0\n");
173 goto again;
174 }
175 #endif
176 #ifdef DEBUG
177 if (statp->options & RES_DEBUG)
178 printf(";; res_query: send error\n");
179 #endif
180 RES_SET_H_ERRNO(statp, TRY_AGAIN);
181 return (n);
182 }
183
184 if (hp->rcode != NOERROR || ntohs(hp->ancount) == 0) {
185 #ifdef DEBUG
186 if (statp->options & RES_DEBUG)
187 printf(";; rcode = (%s), counts = an:%d ns:%d ar:%d\n",
188 p_rcode(hp->rcode),
189 ntohs(hp->ancount),
190 ntohs(hp->nscount),
191 ntohs(hp->arcount));
192 #endif
193 switch (hp->rcode) {
194 case NXDOMAIN:
195 RES_SET_H_ERRNO(statp, HOST_NOT_FOUND);
196 break;
197 case SERVFAIL:
198 RES_SET_H_ERRNO(statp, TRY_AGAIN);
199 break;
200 case NOERROR:
201 RES_SET_H_ERRNO(statp, NO_DATA);
202 break;
203 case FORMERR:
204 case NOTIMP:
205 case REFUSED:
206 default:
207 RES_SET_H_ERRNO(statp, NO_RECOVERY);
208 break;
209 }
210 return (-1);
211 }
212 return (n);
213 }
214
215 /*
216 * Formulate a normal query, send, and retrieve answer in supplied buffer.
217 * Return the size of the response on success, -1 on error.
218 * If enabled, implement search rules until answer or unrecoverable failure
219 * is detected. Error code, if any, is left in H_ERRNO.
220 */
221 int
res_nsearch(res_state statp,const char * name,int class,int type,u_char * answer,int anslen)222 res_nsearch(res_state statp,
223 const char *name, /* domain name */
224 int class, int type, /* class and type of query */
225 u_char *answer, /* buffer to put answer */
226 int anslen) /* size of answer */
227 {
228 const char *cp, * const *domain;
229 HEADER *hp = (HEADER *)(void *)answer;
230 char tmp[NS_MAXDNAME];
231 u_int dots;
232 int trailing_dot, ret, saved_herrno;
233 int got_nodata = 0, got_servfail = 0, root_on_list = 0;
234 int tried_as_is = 0;
235 int searched = 0;
236
237 errno = 0;
238 RES_SET_H_ERRNO(statp, HOST_NOT_FOUND); /* True if we never query. */
239
240 dots = 0;
241 for (cp = name; *cp != '\0'; cp++)
242 dots += (*cp == '.');
243 trailing_dot = 0;
244 if (cp > name && *--cp == '.')
245 trailing_dot++;
246
247 /* If there aren't any dots, it could be a user-level alias. */
248 if (!dots && (cp = res_hostalias(statp, name, tmp, sizeof tmp))!= NULL)
249 return (res_nquery(statp, cp, class, type, answer, anslen));
250
251 /*
252 * If there are enough dots in the name, let's just give it a
253 * try 'as is'. The threshold can be set with the "ndots" option.
254 * Also, query 'as is', if there is a trailing dot in the name.
255 */
256 saved_herrno = -1;
257 if (dots >= statp->ndots || trailing_dot) {
258 ret = res_nquerydomain(statp, name, NULL, class, type,
259 answer, anslen);
260 if (ret > 0 || trailing_dot)
261 return (ret);
262 saved_herrno = statp->res_h_errno;
263 tried_as_is++;
264 }
265
266 /*
267 * We do at least one level of search if
268 * - there is no dot and RES_DEFNAME is set, or
269 * - there is at least one dot, there is no trailing dot,
270 * and RES_DNSRCH is set.
271 */
272 if ((!dots && (statp->options & RES_DEFNAMES) != 0U) ||
273 (dots && !trailing_dot && (statp->options & RES_DNSRCH) != 0U)) {
274 int done = 0;
275
276 /* Unfortunately we need to load network-specific info
277 * (dns servers, search domains) before
278 * the domain stuff is tried. Will have a better
279 * fix after thread pools are used as this will
280 * be loaded once for the thread instead of each
281 * time a query is tried.
282 */
283 _resolv_populate_res_for_net(statp);
284
285 for (domain = (const char * const *)statp->dnsrch;
286 *domain && !done;
287 domain++) {
288 searched = 1;
289
290 if (domain[0][0] == '\0' ||
291 (domain[0][0] == '.' && domain[0][1] == '\0'))
292 root_on_list++;
293
294 ret = res_nquerydomain(statp, name, *domain,
295 class, type,
296 answer, anslen);
297 if (ret > 0)
298 return (ret);
299
300 /*
301 * If no server present, give up.
302 * If name isn't found in this domain,
303 * keep trying higher domains in the search list
304 * (if that's enabled).
305 * On a NO_DATA error, keep trying, otherwise
306 * a wildcard entry of another type could keep us
307 * from finding this entry higher in the domain.
308 * If we get some other error (negative answer or
309 * server failure), then stop searching up,
310 * but try the input name below in case it's
311 * fully-qualified.
312 */
313 if (errno == ECONNREFUSED) {
314 RES_SET_H_ERRNO(statp, TRY_AGAIN);
315 return (-1);
316 }
317
318 switch (statp->res_h_errno) {
319 case NO_DATA:
320 got_nodata++;
321 /* FALLTHROUGH */
322 case HOST_NOT_FOUND:
323 /* keep trying */
324 break;
325 case TRY_AGAIN:
326 if (hp->rcode == SERVFAIL) {
327 /* try next search element, if any */
328 got_servfail++;
329 break;
330 }
331 /* FALLTHROUGH */
332 default:
333 /* anything else implies that we're done */
334 done++;
335 }
336
337 /* if we got here for some reason other than DNSRCH,
338 * we only wanted one iteration of the loop, so stop.
339 */
340 if ((statp->options & RES_DNSRCH) == 0U)
341 done++;
342 }
343 }
344
345 /*
346 * If the query has not already been tried as is then try it
347 * unless RES_NOTLDQUERY is set and there were no dots.
348 */
349 if ((dots || !searched || (statp->options & RES_NOTLDQUERY) == 0U) &&
350 !(tried_as_is || root_on_list)) {
351 ret = res_nquerydomain(statp, name, NULL, class, type,
352 answer, anslen);
353 if (ret > 0)
354 return (ret);
355 }
356
357 /* if we got here, we didn't satisfy the search.
358 * if we did an initial full query, return that query's H_ERRNO
359 * (note that we wouldn't be here if that query had succeeded).
360 * else if we ever got a nodata, send that back as the reason.
361 * else send back meaningless H_ERRNO, that being the one from
362 * the last DNSRCH we did.
363 */
364 if (saved_herrno != -1)
365 RES_SET_H_ERRNO(statp, saved_herrno);
366 else if (got_nodata)
367 RES_SET_H_ERRNO(statp, NO_DATA);
368 else if (got_servfail)
369 RES_SET_H_ERRNO(statp, TRY_AGAIN);
370 return (-1);
371 }
372
373 /*
374 * Perform a call on res_query on the concatenation of name and domain,
375 * removing a trailing dot from name if domain is NULL.
376 */
377 int
res_nquerydomain(res_state statp,const char * name,const char * domain,int class,int type,u_char * answer,int anslen)378 res_nquerydomain(res_state statp,
379 const char *name,
380 const char *domain,
381 int class, int type, /* class and type of query */
382 u_char *answer, /* buffer to put answer */
383 int anslen) /* size of answer */
384 {
385 char nbuf[MAXDNAME];
386 const char *longname = nbuf;
387 int n, d;
388
389 #ifdef DEBUG
390 if (statp->options & RES_DEBUG)
391 printf(";; res_nquerydomain(%s, %s, %d, %d)\n",
392 name, domain?domain:"<Nil>", class, type);
393 #endif
394 if (domain == NULL) {
395 /*
396 * Check for trailing '.';
397 * copy without '.' if present.
398 */
399 n = strlen(name);
400 if (n >= MAXDNAME) {
401 RES_SET_H_ERRNO(statp, NO_RECOVERY);
402 return (-1);
403 }
404 n--;
405 if (n >= 0 && name[n] == '.') {
406 strncpy(nbuf, name, (size_t)n);
407 nbuf[n] = '\0';
408 } else
409 longname = name;
410 } else {
411 n = strlen(name);
412 d = strlen(domain);
413 if (n + d + 1 >= MAXDNAME) {
414 RES_SET_H_ERRNO(statp, NO_RECOVERY);
415 return (-1);
416 }
417 snprintf(nbuf, sizeof(nbuf), "%s.%s", name, domain);
418 }
419 return (res_nquery(statp, longname, class, type, answer, anslen));
420 }
421
422 const char *
res_hostalias(const res_state statp,const char * name,char * dst,size_t siz)423 res_hostalias(const res_state statp, const char *name, char *dst, size_t siz) {
424 return (NULL);
425 }
426