1 /* $NetBSD: res_query.c,v 1.1.1.2 2012/09/09 16:08:08 christos Exp $ */
2
3 /*
4 * Portions Copyright (C) 2004, 2005, 2008 Internet Systems Consortium, Inc. ("ISC")
5 * Portions Copyright (C) 1996-2001, 2003 Internet Software Consortium.
6 *
7 * Permission to use, copy, modify, and/or distribute this software for any
8 * purpose with or without fee is hereby granted, provided that the above
9 * copyright notice and this permission notice appear in all copies.
10 *
11 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
12 * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
13 * AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
14 * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
15 * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
16 * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
17 * PERFORMANCE OF THIS SOFTWARE.
18 */
19
20 /*
21 * Copyright (c) 1988, 1993
22 * The Regents of the University of California. All rights reserved.
23 *
24 * Redistribution and use in source and binary forms, with or without
25 * modification, are permitted provided that the following conditions
26 * are met:
27 * 1. Redistributions of source code must retain the above copyright
28 * notice, this list of conditions and the following disclaimer.
29 * 2. Redistributions in binary form must reproduce the above copyright
30 * notice, this list of conditions and the following disclaimer in the
31 * documentation and/or other materials provided with the distribution.
32 * 3. All advertising materials mentioning features or use of this software
33 * must display the following acknowledgement:
34 * This product includes software developed by the University of
35 * California, Berkeley and its contributors.
36 * 4. Neither the name of the University nor the names of its contributors
37 * may be used to endorse or promote products derived from this software
38 * without specific prior written permission.
39 *
40 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
41 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
42 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
43 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
44 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
45 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
46 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
47 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
48 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
49 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
50 * SUCH DAMAGE.
51 */
52
53 /*
54 * Portions Copyright (c) 1993 by Digital Equipment Corporation.
55 *
56 * Permission to use, copy, modify, and distribute this software for any
57 * purpose with or without fee is hereby granted, provided that the above
58 * copyright notice and this permission notice appear in all copies, and that
59 * the name of Digital Equipment Corporation not be used in advertising or
60 * publicity pertaining to distribution of the document or software without
61 * specific, written prior permission.
62 *
63 * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
64 * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
65 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL DIGITAL EQUIPMENT
66 * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
67 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
68 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
69 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
70 * SOFTWARE.
71 */
72
73 #if defined(LIBC_SCCS) && !defined(lint)
74 static const char sccsid[] = "@(#)res_query.c 8.1 (Berkeley) 6/4/93";
75 static const char rcsid[] = "Id: res_query.c,v 1.11 2008/11/14 02:36:51 marka Exp ";
76 #endif /* LIBC_SCCS and not lint */
77
78 #include "port_before.h"
79 #include <sys/types.h>
80 #include <sys/param.h>
81 #include <netinet/in.h>
82 #include <arpa/inet.h>
83 #include <arpa/nameser.h>
84 #include <ctype.h>
85 #include <errno.h>
86 #include <netdb.h>
87 #include <resolv.h>
88 #include <stdio.h>
89 #include <stdlib.h>
90 #include <string.h>
91 #include "port_after.h"
92
93 /* Options. Leave them on. */
94 #define DEBUG
95
96 #if PACKETSZ > 1024
97 #define MAXPACKET PACKETSZ
98 #else
99 #define MAXPACKET 1024
100 #endif
101
102 /*%
103 * Formulate a normal query, send, and await answer.
104 * Returned answer is placed in supplied buffer "answer".
105 * Perform preliminary check of answer, returning success only
106 * if no error is indicated and the answer count is nonzero.
107 * Return the size of the response on success, -1 on error.
108 * Error number is left in H_ERRNO.
109 *
110 * Caller must parse answer and determine whether it answers the question.
111 */
112 int
res_nquery(res_state statp,const char * name,int class,int type,u_char * answer,int anslen)113 res_nquery(res_state statp,
114 const char *name, /*%< domain name */
115 int class, int type, /*%< class and type of query */
116 u_char *answer, /*%< buffer to put answer */
117 int anslen) /*%< size of answer buffer */
118 {
119 u_char buf[MAXPACKET];
120 HEADER *hp = (HEADER *) answer;
121 u_int oflags;
122 u_char *rdata;
123 int n;
124
125 oflags = statp->_flags;
126
127 again:
128 hp->rcode = NOERROR; /*%< default */
129 #ifdef DEBUG
130 if (statp->options & RES_DEBUG)
131 printf(";; res_query(%s, %d, %d)\n", name, class, type);
132 #endif
133
134 n = res_nmkquery(statp, QUERY, name, class, type, NULL, 0, NULL,
135 buf, sizeof(buf));
136 #ifdef RES_USE_EDNS0
137 if (n > 0 && (statp->_flags & RES_F_EDNS0ERR) == 0 &&
138 (statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC|RES_NSID))) {
139 n = res_nopt(statp, n, buf, sizeof(buf), anslen);
140 rdata = &buf[n];
141 if (n > 0 && (statp->options & RES_NSID) != 0U) {
142 n = res_nopt_rdata(statp, n, buf, sizeof(buf), rdata,
143 NS_OPT_NSID, 0, NULL);
144 }
145 }
146 #endif
147 if (n <= 0) {
148 #ifdef DEBUG
149 if (statp->options & RES_DEBUG)
150 printf(";; res_query: mkquery failed\n");
151 #endif
152 RES_SET_H_ERRNO(statp, NO_RECOVERY);
153 return (n);
154 }
155
156 n = res_nsend(statp, buf, n, answer, anslen);
157 if (n < 0) {
158 #ifdef RES_USE_EDNS0
159 /* if the query choked with EDNS0, retry without EDNS0 */
160 if ((statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0U &&
161 ((oflags ^ statp->_flags) & RES_F_EDNS0ERR) != 0) {
162 statp->_flags |= RES_F_EDNS0ERR;
163 if (statp->options & RES_DEBUG)
164 printf(";; res_nquery: retry without EDNS0\n");
165 goto again;
166 }
167 #endif
168 #ifdef DEBUG
169 if (statp->options & RES_DEBUG)
170 printf(";; res_query: send error\n");
171 #endif
172 RES_SET_H_ERRNO(statp, TRY_AGAIN);
173 return (n);
174 }
175
176 if (hp->rcode != NOERROR || ntohs(hp->ancount) == 0) {
177 #ifdef DEBUG
178 if (statp->options & RES_DEBUG)
179 printf(";; rcode = (%s), counts = an:%d ns:%d ar:%d\n",
180 p_rcode(hp->rcode),
181 ntohs(hp->ancount),
182 ntohs(hp->nscount),
183 ntohs(hp->arcount));
184 #endif
185 switch (hp->rcode) {
186 case NXDOMAIN:
187 RES_SET_H_ERRNO(statp, HOST_NOT_FOUND);
188 break;
189 case SERVFAIL:
190 RES_SET_H_ERRNO(statp, TRY_AGAIN);
191 break;
192 case NOERROR:
193 RES_SET_H_ERRNO(statp, NO_DATA);
194 break;
195 case FORMERR:
196 case NOTIMP:
197 case REFUSED:
198 default:
199 RES_SET_H_ERRNO(statp, NO_RECOVERY);
200 break;
201 }
202 return (-1);
203 }
204 return (n);
205 }
206
207 /*%
208 * Formulate a normal query, send, and retrieve answer in supplied buffer.
209 * Return the size of the response on success, -1 on error.
210 * If enabled, implement search rules until answer or unrecoverable failure
211 * is detected. Error code, if any, is left in H_ERRNO.
212 */
213 int
res_nsearch(res_state statp,const char * name,int class,int type,u_char * answer,int anslen)214 res_nsearch(res_state statp,
215 const char *name, /*%< domain name */
216 int class, int type, /*%< class and type of query */
217 u_char *answer, /*%< buffer to put answer */
218 int anslen) /*%< size of answer */
219 {
220 const char *cp, * const *domain;
221 HEADER *hp = (HEADER *) answer;
222 char tmp[NS_MAXDNAME];
223 u_int dots;
224 int trailing_dot, ret, saved_herrno;
225 int got_nodata = 0, got_servfail = 0, root_on_list = 0;
226 int tried_as_is = 0;
227 int searched = 0;
228
229 errno = 0;
230 RES_SET_H_ERRNO(statp, HOST_NOT_FOUND); /*%< True if we never query. */
231 dots = 0;
232 for (cp = name; *cp != '\0'; cp++)
233 dots += (*cp == '.');
234 trailing_dot = 0;
235 if (cp > name && *--cp == '.')
236 trailing_dot++;
237
238 /* If there aren't any dots, it could be a user-level alias. */
239 if (!dots && (cp = res_hostalias(statp, name, tmp, sizeof tmp))!= NULL)
240 return (res_nquery(statp, cp, class, type, answer, anslen));
241
242 /*
243 * If there are enough dots in the name, let's just give it a
244 * try 'as is'. The threshold can be set with the "ndots" option.
245 * Also, query 'as is', if there is a trailing dot in the name.
246 */
247 saved_herrno = -1;
248 if (dots >= statp->ndots || trailing_dot) {
249 ret = res_nquerydomain(statp, name, NULL, class, type,
250 answer, anslen);
251 if (ret > 0 || trailing_dot)
252 return (ret);
253 saved_herrno = statp->res_h_errno;
254 tried_as_is++;
255 }
256
257 /*
258 * We do at least one level of search if
259 * - there is no dot and RES_DEFNAME is set, or
260 * - there is at least one dot, there is no trailing dot,
261 * and RES_DNSRCH is set.
262 */
263 if ((!dots && (statp->options & RES_DEFNAMES) != 0U) ||
264 (dots && !trailing_dot && (statp->options & RES_DNSRCH) != 0U)) {
265 int done = 0;
266
267 for (domain = (const char * const *)statp->dnsrch;
268 *domain && !done;
269 domain++) {
270 searched = 1;
271
272 if (domain[0][0] == '\0' ||
273 (domain[0][0] == '.' && domain[0][1] == '\0'))
274 root_on_list++;
275
276 ret = res_nquerydomain(statp, name, *domain,
277 class, type,
278 answer, anslen);
279 if (ret > 0)
280 return (ret);
281
282 /*
283 * If no server present, give up.
284 * If name isn't found in this domain,
285 * keep trying higher domains in the search list
286 * (if that's enabled).
287 * On a NO_DATA error, keep trying, otherwise
288 * a wildcard entry of another type could keep us
289 * from finding this entry higher in the domain.
290 * If we get some other error (negative answer or
291 * server failure), then stop searching up,
292 * but try the input name below in case it's
293 * fully-qualified.
294 */
295 if (errno == ECONNREFUSED) {
296 RES_SET_H_ERRNO(statp, TRY_AGAIN);
297 return (-1);
298 }
299
300 switch (statp->res_h_errno) {
301 case NO_DATA:
302 got_nodata++;
303 /* FALLTHROUGH */
304 case HOST_NOT_FOUND:
305 /* keep trying */
306 break;
307 case TRY_AGAIN:
308 if (hp->rcode == SERVFAIL) {
309 /* try next search element, if any */
310 got_servfail++;
311 break;
312 }
313 /* FALLTHROUGH */
314 default:
315 /* anything else implies that we're done */
316 done++;
317 }
318
319 /* if we got here for some reason other than DNSRCH,
320 * we only wanted one iteration of the loop, so stop.
321 */
322 if ((statp->options & RES_DNSRCH) == 0U)
323 done++;
324 }
325 }
326
327 /*
328 * If the query has not already been tried as is then try it
329 * unless RES_NOTLDQUERY is set and there were no dots.
330 */
331 if ((dots || !searched || (statp->options & RES_NOTLDQUERY) == 0U) &&
332 !(tried_as_is || root_on_list)) {
333 ret = res_nquerydomain(statp, name, NULL, class, type,
334 answer, anslen);
335 if (ret > 0)
336 return (ret);
337 }
338
339 /* if we got here, we didn't satisfy the search.
340 * if we did an initial full query, return that query's H_ERRNO
341 * (note that we wouldn't be here if that query had succeeded).
342 * else if we ever got a nodata, send that back as the reason.
343 * else send back meaningless H_ERRNO, that being the one from
344 * the last DNSRCH we did.
345 */
346 if (saved_herrno != -1)
347 RES_SET_H_ERRNO(statp, saved_herrno);
348 else if (got_nodata)
349 RES_SET_H_ERRNO(statp, NO_DATA);
350 else if (got_servfail)
351 RES_SET_H_ERRNO(statp, TRY_AGAIN);
352 return (-1);
353 }
354
355 /*%
356 * Perform a call on res_query on the concatenation of name and domain,
357 * removing a trailing dot from name if domain is NULL.
358 */
359 int
res_nquerydomain(res_state statp,const char * name,const char * domain,int class,int type,u_char * answer,int anslen)360 res_nquerydomain(res_state statp,
361 const char *name,
362 const char *domain,
363 int class, int type, /*%< class and type of query */
364 u_char *answer, /*%< buffer to put answer */
365 int anslen) /*%< size of answer */
366 {
367 char nbuf[MAXDNAME];
368 const char *longname = nbuf;
369 int n, d;
370
371 #ifdef DEBUG
372 if (statp->options & RES_DEBUG)
373 printf(";; res_nquerydomain(%s, %s, %d, %d)\n",
374 name, domain?domain:"<Nil>", class, type);
375 #endif
376 if (domain == NULL) {
377 /*
378 * Check for trailing '.';
379 * copy without '.' if present.
380 */
381 n = strlen(name);
382 if (n >= MAXDNAME) {
383 RES_SET_H_ERRNO(statp, NO_RECOVERY);
384 return (-1);
385 }
386 n--;
387 if (n >= 0 && name[n] == '.') {
388 strncpy(nbuf, name, n);
389 nbuf[n] = '\0';
390 } else
391 longname = name;
392 } else {
393 n = strlen(name);
394 d = strlen(domain);
395 if (n + d + 1 >= MAXDNAME) {
396 RES_SET_H_ERRNO(statp, NO_RECOVERY);
397 return (-1);
398 }
399 sprintf(nbuf, "%s.%s", name, domain);
400 }
401 return (res_nquery(statp, longname, class, type, answer, anslen));
402 }
403
404 const char *
res_hostalias(const res_state statp,const char * name,char * dst,size_t siz)405 res_hostalias(const res_state statp, const char *name, char *dst, size_t siz) {
406 char *file, *cp1, *cp2;
407 char buf[BUFSIZ];
408 FILE *fp;
409
410 if (statp->options & RES_NOALIASES)
411 return (NULL);
412 file = getenv("HOSTALIASES");
413 if (file == NULL || (fp = fopen(file, "r")) == NULL)
414 return (NULL);
415 setbuf(fp, NULL);
416 buf[sizeof(buf) - 1] = '\0';
417 while (fgets(buf, sizeof(buf), fp)) {
418 for (cp1 = buf; *cp1 && !isspace((unsigned char)*cp1); ++cp1)
419 ;
420 if (!*cp1)
421 break;
422 *cp1 = '\0';
423 if (ns_samename(buf, name) == 1) {
424 while (isspace((unsigned char)*++cp1))
425 ;
426 if (!*cp1)
427 break;
428 for (cp2 = cp1 + 1; *cp2 &&
429 !isspace((unsigned char)*cp2); ++cp2)
430 ;
431 *cp2 = '\0';
432 strncpy(dst, cp1, siz - 1);
433 dst[siz - 1] = '\0';
434 fclose(fp);
435 return (dst);
436 }
437 }
438 fclose(fp);
439 return (NULL);
440 }
441
442 /*! \file */
443