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