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_private.h"
95 #else
96 #include <resolv.h>
97 #endif
98 #include <stdio.h>
99 #include <stdlib.h>
100 #include <unistd.h>
101 #include <string.h>
102
103 #define DISABLE_HOST_ALIAS 1
104
105 /* Options. Leave them on. */
106 #ifndef DEBUG
107 #define DEBUG
108 #endif
109
110 #if PACKETSZ > 1024
111 #define MAXPACKET PACKETSZ
112 #else
113 #define MAXPACKET 1024
114 #endif
115
116 /*
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.
123 *
124 * Caller must parse answer and determine whether it answers the question.
125 */
126 int
res_nquery(res_state statp,const char * name,int class,int type,u_char * answer,int anslen)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 */
132 {
133 u_char buf[MAXPACKET];
134 HEADER *hp = (HEADER *)(void *)answer;
135 int n;
136 u_int oflags;
137
138 oflags = statp->_flags;
139
140 again:
141 hp->rcode = NOERROR; /* default */
142
143 #ifdef DEBUG
144 if (statp->options & RES_DEBUG)
145 printf(";; res_query(%s, %d, %d)\n", name, class, type);
146 #endif
147
148 n = res_nmkquery(statp, QUERY, name, class, type, NULL, 0, NULL,
149 buf, sizeof(buf));
150 #ifdef RES_USE_EDNS0
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);
154 #endif
155 if (n <= 0) {
156 #ifdef DEBUG
157 if (statp->options & RES_DEBUG)
158 printf(";; res_query: mkquery failed\n");
159 #endif
160 RES_SET_H_ERRNO(statp, NO_RECOVERY);
161 return (n);
162 }
163 n = res_nsend(statp, buf, n, answer, anslen);
164 if (n < 0) {
165 #ifdef RES_USE_EDNS0
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");
172 goto again;
173 }
174 #endif
175 #ifdef DEBUG
176 if (statp->options & RES_DEBUG)
177 printf(";; res_query: send error\n");
178 #endif
179 RES_SET_H_ERRNO(statp, TRY_AGAIN);
180 return (n);
181 }
182
183 if (hp->rcode != NOERROR || ntohs(hp->ancount) == 0) {
184 #ifdef DEBUG
185 if (statp->options & RES_DEBUG)
186 printf(";; rcode = (%s), counts = an:%d ns:%d ar:%d\n",
187 p_rcode(hp->rcode),
188 ntohs(hp->ancount),
189 ntohs(hp->nscount),
190 ntohs(hp->arcount));
191 #endif
192 switch (hp->rcode) {
193 case NXDOMAIN:
194 RES_SET_H_ERRNO(statp, HOST_NOT_FOUND);
195 break;
196 case SERVFAIL:
197 RES_SET_H_ERRNO(statp, TRY_AGAIN);
198 break;
199 case NOERROR:
200 RES_SET_H_ERRNO(statp, NO_DATA);
201 break;
202 case FORMERR:
203 case NOTIMP:
204 case REFUSED:
205 default:
206 RES_SET_H_ERRNO(statp, NO_RECOVERY);
207 break;
208 }
209 return (-1);
210 }
211 return (n);
212 }
213
214 /*
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.
219 */
220 int
res_nsearch(res_state statp,const char * name,int class,int type,u_char * answer,int anslen)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 */
226 {
227 const char *cp, * const *domain;
228 HEADER *hp = (HEADER *)(void *)answer;
229 char tmp[NS_MAXDNAME];
230 u_int dots;
231 int trailing_dot, ret, saved_herrno;
232 int got_nodata = 0, got_servfail = 0, root_on_list = 0;
233 int tried_as_is = 0;
234 int searched = 0;
235
236 errno = 0;
237 RES_SET_H_ERRNO(statp, HOST_NOT_FOUND); /* True if we never query. */
238
239 dots = 0;
240 for (cp = name; *cp != '\0'; cp++)
241 dots += (*cp == '.');
242 trailing_dot = 0;
243 if (cp > name && *--cp == '.')
244 trailing_dot++;
245
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));
249
250 /*
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.
254 */
255 saved_herrno = -1;
256 if (dots >= statp->ndots || trailing_dot) {
257 ret = res_nquerydomain(statp, name, NULL, class, type,
258 answer, anslen);
259 if (ret > 0 || trailing_dot)
260 return (ret);
261 saved_herrno = statp->res_h_errno;
262 tried_as_is++;
263 }
264
265 /*
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.
270 */
271 if ((!dots && (statp->options & RES_DEFNAMES) != 0U) ||
272 (dots && !trailing_dot && (statp->options & RES_DNSRCH) != 0U)) {
273 int done = 0;
274
275 for (domain = (const char * const *)statp->dnsrch;
276 *domain && !done;
277 domain++) {
278 searched = 1;
279
280 if (domain[0][0] == '\0' ||
281 (domain[0][0] == '.' && domain[0][1] == '\0'))
282 root_on_list++;
283
284 ret = res_nquerydomain(statp, name, *domain,
285 class, type,
286 answer, anslen);
287 if (ret > 0)
288 return (ret);
289
290 /*
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
301 * fully-qualified.
302 */
303 if (errno == ECONNREFUSED) {
304 RES_SET_H_ERRNO(statp, TRY_AGAIN);
305 return (-1);
306 }
307
308 switch (statp->res_h_errno) {
309 case NO_DATA:
310 got_nodata++;
311 /* FALLTHROUGH */
312 case HOST_NOT_FOUND:
313 /* keep trying */
314 break;
315 case TRY_AGAIN:
316 if (hp->rcode == SERVFAIL) {
317 /* try next search element, if any */
318 got_servfail++;
319 break;
320 }
321 /* FALLTHROUGH */
322 default:
323 /* anything else implies that we're done */
324 done++;
325 }
326
327 /* if we got here for some reason other than DNSRCH,
328 * we only wanted one iteration of the loop, so stop.
329 */
330 if ((statp->options & RES_DNSRCH) == 0U)
331 done++;
332 }
333 }
334
335 /*
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.
338 */
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,
342 answer, anslen);
343 if (ret > 0)
344 return (ret);
345 }
346
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.
353 */
354 if (saved_herrno != -1)
355 RES_SET_H_ERRNO(statp, saved_herrno);
356 else if (got_nodata)
357 RES_SET_H_ERRNO(statp, NO_DATA);
358 else if (got_servfail)
359 RES_SET_H_ERRNO(statp, TRY_AGAIN);
360 return (-1);
361 }
362
363 /*
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.
366 */
367 int
res_nquerydomain(res_state statp,const char * name,const char * domain,int class,int type,u_char * answer,int anslen)368 res_nquerydomain(res_state statp,
369 const char *name,
370 const char *domain,
371 int class, int type, /* class and type of query */
372 u_char *answer, /* buffer to put answer */
373 int anslen) /* size of answer */
374 {
375 char nbuf[MAXDNAME];
376 const char *longname = nbuf;
377 int n, d;
378
379 #ifdef DEBUG
380 if (statp->options & RES_DEBUG)
381 printf(";; res_nquerydomain(%s, %s, %d, %d)\n",
382 name, domain?domain:"<Nil>", class, type);
383 #endif
384 if (domain == NULL) {
385 /*
386 * Check for trailing '.';
387 * copy without '.' if present.
388 */
389 n = strlen(name);
390 if (n >= MAXDNAME) {
391 RES_SET_H_ERRNO(statp, NO_RECOVERY);
392 return (-1);
393 }
394 n--;
395 if (n >= 0 && name[n] == '.') {
396 strncpy(nbuf, name, (size_t)n);
397 nbuf[n] = '\0';
398 } else
399 longname = name;
400 } else {
401 n = strlen(name);
402 d = strlen(domain);
403 if (n + d + 1 >= MAXDNAME) {
404 RES_SET_H_ERRNO(statp, NO_RECOVERY);
405 return (-1);
406 }
407 sprintf(nbuf, "%s.%s", name, domain);
408 }
409 return (res_nquery(statp, longname, class, type, answer, anslen));
410 }
411
412 const char *
res_hostalias(const res_state statp,const char * name,char * dst,size_t siz)413 res_hostalias(const res_state statp, const char *name, char *dst, size_t siz) {
414 return (NULL);
415 }
416