1/*
2 * Copyright (c) 1988, 1993
3 * The Regents of the University of California. All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 4. Neither the name of the University nor the names of its contributors
14 * may be used to endorse or promote products derived from this software
15 * without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 */
29
30/*
31 * Portions Copyright (c) 1993 by Digital Equipment Corporation.
32 *
33 * Permission to use, copy, modify, and distribute this software for any
34 * purpose with or without fee is hereby granted, provided that the above
35 * copyright notice and this permission notice appear in all copies, and that
36 * the name of Digital Equipment Corporation not be used in advertising or
37 * publicity pertaining to distribution of the document or software without
38 * specific, written prior permission.
39 *
40 * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
41 * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
42 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL DIGITAL EQUIPMENT
43 * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
44 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
45 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
46 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
47 * SOFTWARE.
48 */
49
50/*
51 * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
52 * Portions Copyright (c) 1996-1999 by Internet Software Consortium.
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.
57 *
58 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
59 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
60 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR
61 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
62 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
63 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
64 * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
65 */
66
67#if defined(LIBC_SCCS) && !defined(lint)
68static const char sccsid[] = "@(#)res_query.c 8.1 (Berkeley) 6/4/93";
69static const char rcsid[] = "$Id: res_query.c,v 1.7.18.2 2008/04/03 23:15:15 marka Exp $";
70#endif /* LIBC_SCCS and not lint */
71#include <sys/cdefs.h>
| 1/*
2 * Copyright (c) 1988, 1993
3 * The Regents of the University of California. All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 4. Neither the name of the University nor the names of its contributors
14 * may be used to endorse or promote products derived from this software
15 * without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 */
29
30/*
31 * Portions Copyright (c) 1993 by Digital Equipment Corporation.
32 *
33 * Permission to use, copy, modify, and distribute this software for any
34 * purpose with or without fee is hereby granted, provided that the above
35 * copyright notice and this permission notice appear in all copies, and that
36 * the name of Digital Equipment Corporation not be used in advertising or
37 * publicity pertaining to distribution of the document or software without
38 * specific, written prior permission.
39 *
40 * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
41 * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
42 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL DIGITAL EQUIPMENT
43 * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
44 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
45 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
46 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
47 * SOFTWARE.
48 */
49
50/*
51 * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
52 * Portions Copyright (c) 1996-1999 by Internet Software Consortium.
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.
57 *
58 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
59 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
60 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR
61 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
62 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
63 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
64 * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
65 */
66
67#if defined(LIBC_SCCS) && !defined(lint)
68static const char sccsid[] = "@(#)res_query.c 8.1 (Berkeley) 6/4/93";
69static const char rcsid[] = "$Id: res_query.c,v 1.7.18.2 2008/04/03 23:15:15 marka Exp $";
70#endif /* LIBC_SCCS and not lint */
71#include <sys/cdefs.h>
|
73
74#include "port_before.h"
75#include <sys/types.h>
76#include <sys/param.h>
77#include <netinet/in.h>
78#include <arpa/inet.h>
79#include <arpa/nameser.h>
80#include <ctype.h>
81#include <errno.h>
82#include <netdb.h>
83#include <resolv.h>
84#include <stdio.h>
85#include <stdlib.h>
86#include <string.h>
87#include <unistd.h>
88#include "port_after.h"
89
90/* Options. Leave them on. */
91#define DEBUG
92
93#if PACKETSZ > 1024
94#define MAXPACKET PACKETSZ
95#else
96#define MAXPACKET 1024
97#endif
98
99/*%
100 * Formulate a normal query, send, and await answer.
101 * Returned answer is placed in supplied buffer "answer".
102 * Perform preliminary check of answer, returning success only
103 * if no error is indicated and the answer count is nonzero.
104 * Return the size of the response on success, -1 on error.
105 * Error number is left in H_ERRNO.
106 *
107 * Caller must parse answer and determine whether it answers the question.
108 */
109int
110res_nquery(res_state statp,
111 const char *name, /*%< domain name */
112 int class, int type, /*%< class and type of query */
113 u_char *answer, /*%< buffer to put answer */
114 int anslen) /*%< size of answer buffer */
115{
116 u_char buf[MAXPACKET];
117 HEADER *hp = (HEADER *) answer;
118 u_int oflags;
119 u_char *rdata;
120 int n;
121
122 oflags = statp->_flags;
123
124again:
125 hp->rcode = NOERROR; /*%< default */
126#ifdef DEBUG
127 if (statp->options & RES_DEBUG)
128 printf(";; res_query(%s, %d, %d)\n", name, class, type);
129#endif
130
131 n = res_nmkquery(statp, QUERY, name, class, type, NULL, 0, NULL,
132 buf, sizeof(buf));
133#ifdef RES_USE_EDNS0
134 if (n > 0 && (statp->_flags & RES_F_EDNS0ERR) == 0 &&
135 (statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC|RES_NSID))) {
136 n = res_nopt(statp, n, buf, sizeof(buf), anslen);
137 rdata = &buf[n];
138 if (n > 0 && (statp->options & RES_NSID) != 0U) {
139 n = res_nopt_rdata(statp, n, buf, sizeof(buf), rdata,
140 NS_OPT_NSID, 0, NULL);
141 }
142 }
143#endif
144 if (n <= 0) {
145#ifdef DEBUG
146 if (statp->options & RES_DEBUG)
147 printf(";; res_query: mkquery failed\n");
148#endif
149 RES_SET_H_ERRNO(statp, NO_RECOVERY);
150 return (n);
151 }
152
153 n = res_nsend(statp, buf, n, answer, anslen);
154 if (n < 0) {
155#ifdef RES_USE_EDNS0
156 /* if the query choked with EDNS0, retry without EDNS0 */
157 if ((statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0U &&
158 ((oflags ^ statp->_flags) & RES_F_EDNS0ERR) != 0) {
159 statp->_flags |= RES_F_EDNS0ERR;
160 if (statp->options & RES_DEBUG)
161 printf(";; res_nquery: retry without EDNS0\n");
162 goto again;
163 }
164#endif
165#ifdef DEBUG
166 if (statp->options & RES_DEBUG)
167 printf(";; res_query: send error\n");
168#endif
169 RES_SET_H_ERRNO(statp, TRY_AGAIN);
170 return (n);
171 }
172
173 if (hp->rcode != NOERROR || ntohs(hp->ancount) == 0) {
174#ifdef DEBUG
175 if (statp->options & RES_DEBUG)
176 printf(";; rcode = (%s), counts = an:%d ns:%d ar:%d\n",
177 p_rcode(hp->rcode),
178 ntohs(hp->ancount),
179 ntohs(hp->nscount),
180 ntohs(hp->arcount));
181#endif
182 switch (hp->rcode) {
183 case NXDOMAIN:
184 RES_SET_H_ERRNO(statp, HOST_NOT_FOUND);
185 break;
186 case SERVFAIL:
187 RES_SET_H_ERRNO(statp, TRY_AGAIN);
188 break;
189 case NOERROR:
190 RES_SET_H_ERRNO(statp, NO_DATA);
191 break;
192 case FORMERR:
193 case NOTIMP:
194 case REFUSED:
195 default:
196 RES_SET_H_ERRNO(statp, NO_RECOVERY);
197 break;
198 }
199 return (-1);
200 }
201 return (n);
202}
203
204/*%
205 * Formulate a normal query, send, and retrieve answer in supplied buffer.
206 * Return the size of the response on success, -1 on error.
207 * If enabled, implement search rules until answer or unrecoverable failure
208 * is detected. Error code, if any, is left in H_ERRNO.
209 */
210int
211res_nsearch(res_state statp,
212 const char *name, /*%< domain name */
213 int class, int type, /*%< class and type of query */
214 u_char *answer, /*%< buffer to put answer */
215 int anslen) /*%< size of answer */
216{
217 const char *cp, * const *domain;
218 HEADER *hp = (HEADER *) answer;
219 char tmp[NS_MAXDNAME];
220 u_int dots;
221 int trailing_dot, ret, saved_herrno;
222 int got_nodata = 0, got_servfail = 0, root_on_list = 0;
223 int tried_as_is = 0;
224 int searched = 0;
225
226 errno = 0;
227 RES_SET_H_ERRNO(statp, HOST_NOT_FOUND); /*%< True if we never query. */
228 dots = 0;
229 for (cp = name; *cp != '\0'; cp++)
230 dots += (*cp == '.');
231 trailing_dot = 0;
232 if (cp > name && *--cp == '.')
233 trailing_dot++;
234
235 /* If there aren't any dots, it could be a user-level alias. */
236 if (!dots && (cp = res_hostalias(statp, name, tmp, sizeof tmp))!= NULL)
237 return (res_nquery(statp, cp, class, type, answer, anslen));
238
239 /*
240 * If there are enough dots in the name, let's just give it a
241 * try 'as is'. The threshold can be set with the "ndots" option.
242 * Also, query 'as is', if there is a trailing dot in the name.
243 */
244 saved_herrno = -1;
245 if (dots >= statp->ndots || trailing_dot) {
246 ret = res_nquerydomain(statp, name, NULL, class, type,
247 answer, anslen);
248 if (ret > 0 || trailing_dot)
249 return (ret);
250 if (errno == ECONNREFUSED) {
251 RES_SET_H_ERRNO(statp, TRY_AGAIN);
252 return (-1);
253 }
254 switch (statp->res_h_errno) {
255 case NO_DATA:
256 case HOST_NOT_FOUND:
257 break;
258 case TRY_AGAIN:
259 if (hp->rcode == SERVFAIL)
260 break;
261 /* FALLTHROUGH */
262 default:
263 return (-1);
264 }
265 saved_herrno = statp->res_h_errno;
266 tried_as_is++;
267 }
268
269 /*
270 * We do at least one level of search if
271 * - there is no dot and RES_DEFNAME is set, or
272 * - there is at least one dot, there is no trailing dot,
273 * and RES_DNSRCH is set.
274 */
275 if ((!dots && (statp->options & RES_DEFNAMES) != 0U) ||
276 (dots && !trailing_dot && (statp->options & RES_DNSRCH) != 0U)) {
277 int done = 0;
278
279 for (domain = (const char * const *)statp->dnsrch;
280 *domain && !done;
281 domain++) {
282 searched = 1;
283
284 if (domain[0][0] == '\0' ||
285 (domain[0][0] == '.' && domain[0][1] == '\0'))
286 root_on_list++;
287
288 if (root_on_list && tried_as_is)
289 continue;
290
291 ret = res_nquerydomain(statp, name, *domain,
292 class, type,
293 answer, anslen);
294 if (ret > 0)
295 return (ret);
296
297 /*
298 * If no server present, give up.
299 * If name isn't found in this domain,
300 * keep trying higher domains in the search list
301 * (if that's enabled).
302 * On a NO_DATA error, keep trying, otherwise
303 * a wildcard entry of another type could keep us
304 * from finding this entry higher in the domain.
305 * If we get some other error (negative answer or
306 * server failure), then stop searching up,
307 * but try the input name below in case it's
308 * fully-qualified.
309 */
310 if (errno == ECONNREFUSED) {
311 RES_SET_H_ERRNO(statp, TRY_AGAIN);
312 return (-1);
313 }
314
315 switch (statp->res_h_errno) {
316 case NO_DATA:
317 got_nodata++;
318 /* FALLTHROUGH */
319 case HOST_NOT_FOUND:
320 /* keep trying */
321 break;
322 case TRY_AGAIN:
323 /*
324 * This can occur due to a server failure
325 * (that is, all listed servers have failed),
326 * or all listed servers have timed out.
327 * ((HEADER *)answer)->rcode may not be set
328 * to SERVFAIL in the case of a timeout.
329 *
330 * Either way we must return TRY_AGAIN in
331 * order to avoid non-deterministic
332 * return codes.
333 * For example, loaded name servers or races
334 * against network startup/validation (dhcp,
335 * ppp, etc) can cause the search to timeout
336 * on one search element, e.g. 'fu.bar.com',
337 * and return a definitive failure on the
338 * next search element, e.g. 'fu.'.
339 */
340 got_servfail++;
341 if (hp->rcode == SERVFAIL) {
342 /* try next search element, if any */
343 break;
344 }
345 /* FALLTHROUGH */
346 default:
347 /* anything else implies that we're done */
348 done++;
349 }
350
351 /* if we got here for some reason other than DNSRCH,
352 * we only wanted one iteration of the loop, so stop.
353 */
354 if ((statp->options & RES_DNSRCH) == 0U)
355 done++;
356 }
357 }
358
359 switch (statp->res_h_errno) {
360 case NO_DATA:
361 case HOST_NOT_FOUND:
362 break;
363 case TRY_AGAIN:
364 if (hp->rcode == SERVFAIL)
365 break;
366 /* FALLTHROUGH */
367 default:
368 goto giveup;
369 }
370
371 /*
372 * If the query has not already been tried as is then try it
373 * unless RES_NOTLDQUERY is set and there were no dots.
374 */
375 if ((dots || !searched || (statp->options & RES_NOTLDQUERY) == 0U) &&
376 !(tried_as_is || root_on_list)) {
377 ret = res_nquerydomain(statp, name, NULL, class, type,
378 answer, anslen);
379 if (ret > 0)
380 return (ret);
381 }
382
383 /* if we got here, we didn't satisfy the search.
384 * if we did an initial full query, return that query's H_ERRNO
385 * (note that we wouldn't be here if that query had succeeded).
386 * else if we ever got a nodata, send that back as the reason.
387 * else send back meaningless H_ERRNO, that being the one from
388 * the last DNSRCH we did.
389 */
390giveup:
391 if (saved_herrno != -1)
392 RES_SET_H_ERRNO(statp, saved_herrno);
393 else if (got_nodata)
394 RES_SET_H_ERRNO(statp, NO_DATA);
395 else if (got_servfail)
396 RES_SET_H_ERRNO(statp, TRY_AGAIN);
397 return (-1);
398}
399
400/*%
401 * Perform a call on res_query on the concatenation of name and domain,
402 * removing a trailing dot from name if domain is NULL.
403 */
404int
405res_nquerydomain(res_state statp,
406 const char *name,
407 const char *domain,
408 int class, int type, /*%< class and type of query */
409 u_char *answer, /*%< buffer to put answer */
410 int anslen) /*%< size of answer */
411{
412 char nbuf[MAXDNAME];
413 const char *longname = nbuf;
414 int n, d;
415
416#ifdef DEBUG
417 if (statp->options & RES_DEBUG)
418 printf(";; res_nquerydomain(%s, %s, %d, %d)\n",
419 name, domain?domain:"<Nil>", class, type);
420#endif
421 if (domain == NULL) {
422 /*
423 * Check for trailing '.';
424 * copy without '.' if present.
425 */
426 n = strlen(name);
427 if (n >= MAXDNAME) {
428 RES_SET_H_ERRNO(statp, NO_RECOVERY);
429 return (-1);
430 }
431 n--;
432 if (n >= 0 && name[n] == '.') {
433 strncpy(nbuf, name, n);
434 nbuf[n] = '\0';
435 } else
436 longname = name;
437 } else {
438 n = strlen(name);
439 d = strlen(domain);
440 if (n + d + 1 >= MAXDNAME) {
441 RES_SET_H_ERRNO(statp, NO_RECOVERY);
442 return (-1);
443 }
444 sprintf(nbuf, "%s.%s", name, domain);
445 }
446 return (res_nquery(statp, longname, class, type, answer, anslen));
447}
448
449const char *
450res_hostalias(const res_state statp, const char *name, char *dst, size_t siz) {
451 char *file, *cp1, *cp2;
452 char buf[BUFSIZ];
453 FILE *fp;
454
455 if (statp->options & RES_NOALIASES)
456 return (NULL);
457 if (issetugid())
458 return (NULL);
459 file = getenv("HOSTALIASES");
| 73
74#include "port_before.h"
75#include <sys/types.h>
76#include <sys/param.h>
77#include <netinet/in.h>
78#include <arpa/inet.h>
79#include <arpa/nameser.h>
80#include <ctype.h>
81#include <errno.h>
82#include <netdb.h>
83#include <resolv.h>
84#include <stdio.h>
85#include <stdlib.h>
86#include <string.h>
87#include <unistd.h>
88#include "port_after.h"
89
90/* Options. Leave them on. */
91#define DEBUG
92
93#if PACKETSZ > 1024
94#define MAXPACKET PACKETSZ
95#else
96#define MAXPACKET 1024
97#endif
98
99/*%
100 * Formulate a normal query, send, and await answer.
101 * Returned answer is placed in supplied buffer "answer".
102 * Perform preliminary check of answer, returning success only
103 * if no error is indicated and the answer count is nonzero.
104 * Return the size of the response on success, -1 on error.
105 * Error number is left in H_ERRNO.
106 *
107 * Caller must parse answer and determine whether it answers the question.
108 */
109int
110res_nquery(res_state statp,
111 const char *name, /*%< domain name */
112 int class, int type, /*%< class and type of query */
113 u_char *answer, /*%< buffer to put answer */
114 int anslen) /*%< size of answer buffer */
115{
116 u_char buf[MAXPACKET];
117 HEADER *hp = (HEADER *) answer;
118 u_int oflags;
119 u_char *rdata;
120 int n;
121
122 oflags = statp->_flags;
123
124again:
125 hp->rcode = NOERROR; /*%< default */
126#ifdef DEBUG
127 if (statp->options & RES_DEBUG)
128 printf(";; res_query(%s, %d, %d)\n", name, class, type);
129#endif
130
131 n = res_nmkquery(statp, QUERY, name, class, type, NULL, 0, NULL,
132 buf, sizeof(buf));
133#ifdef RES_USE_EDNS0
134 if (n > 0 && (statp->_flags & RES_F_EDNS0ERR) == 0 &&
135 (statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC|RES_NSID))) {
136 n = res_nopt(statp, n, buf, sizeof(buf), anslen);
137 rdata = &buf[n];
138 if (n > 0 && (statp->options & RES_NSID) != 0U) {
139 n = res_nopt_rdata(statp, n, buf, sizeof(buf), rdata,
140 NS_OPT_NSID, 0, NULL);
141 }
142 }
143#endif
144 if (n <= 0) {
145#ifdef DEBUG
146 if (statp->options & RES_DEBUG)
147 printf(";; res_query: mkquery failed\n");
148#endif
149 RES_SET_H_ERRNO(statp, NO_RECOVERY);
150 return (n);
151 }
152
153 n = res_nsend(statp, buf, n, answer, anslen);
154 if (n < 0) {
155#ifdef RES_USE_EDNS0
156 /* if the query choked with EDNS0, retry without EDNS0 */
157 if ((statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0U &&
158 ((oflags ^ statp->_flags) & RES_F_EDNS0ERR) != 0) {
159 statp->_flags |= RES_F_EDNS0ERR;
160 if (statp->options & RES_DEBUG)
161 printf(";; res_nquery: retry without EDNS0\n");
162 goto again;
163 }
164#endif
165#ifdef DEBUG
166 if (statp->options & RES_DEBUG)
167 printf(";; res_query: send error\n");
168#endif
169 RES_SET_H_ERRNO(statp, TRY_AGAIN);
170 return (n);
171 }
172
173 if (hp->rcode != NOERROR || ntohs(hp->ancount) == 0) {
174#ifdef DEBUG
175 if (statp->options & RES_DEBUG)
176 printf(";; rcode = (%s), counts = an:%d ns:%d ar:%d\n",
177 p_rcode(hp->rcode),
178 ntohs(hp->ancount),
179 ntohs(hp->nscount),
180 ntohs(hp->arcount));
181#endif
182 switch (hp->rcode) {
183 case NXDOMAIN:
184 RES_SET_H_ERRNO(statp, HOST_NOT_FOUND);
185 break;
186 case SERVFAIL:
187 RES_SET_H_ERRNO(statp, TRY_AGAIN);
188 break;
189 case NOERROR:
190 RES_SET_H_ERRNO(statp, NO_DATA);
191 break;
192 case FORMERR:
193 case NOTIMP:
194 case REFUSED:
195 default:
196 RES_SET_H_ERRNO(statp, NO_RECOVERY);
197 break;
198 }
199 return (-1);
200 }
201 return (n);
202}
203
204/*%
205 * Formulate a normal query, send, and retrieve answer in supplied buffer.
206 * Return the size of the response on success, -1 on error.
207 * If enabled, implement search rules until answer or unrecoverable failure
208 * is detected. Error code, if any, is left in H_ERRNO.
209 */
210int
211res_nsearch(res_state statp,
212 const char *name, /*%< domain name */
213 int class, int type, /*%< class and type of query */
214 u_char *answer, /*%< buffer to put answer */
215 int anslen) /*%< size of answer */
216{
217 const char *cp, * const *domain;
218 HEADER *hp = (HEADER *) answer;
219 char tmp[NS_MAXDNAME];
220 u_int dots;
221 int trailing_dot, ret, saved_herrno;
222 int got_nodata = 0, got_servfail = 0, root_on_list = 0;
223 int tried_as_is = 0;
224 int searched = 0;
225
226 errno = 0;
227 RES_SET_H_ERRNO(statp, HOST_NOT_FOUND); /*%< True if we never query. */
228 dots = 0;
229 for (cp = name; *cp != '\0'; cp++)
230 dots += (*cp == '.');
231 trailing_dot = 0;
232 if (cp > name && *--cp == '.')
233 trailing_dot++;
234
235 /* If there aren't any dots, it could be a user-level alias. */
236 if (!dots && (cp = res_hostalias(statp, name, tmp, sizeof tmp))!= NULL)
237 return (res_nquery(statp, cp, class, type, answer, anslen));
238
239 /*
240 * If there are enough dots in the name, let's just give it a
241 * try 'as is'. The threshold can be set with the "ndots" option.
242 * Also, query 'as is', if there is a trailing dot in the name.
243 */
244 saved_herrno = -1;
245 if (dots >= statp->ndots || trailing_dot) {
246 ret = res_nquerydomain(statp, name, NULL, class, type,
247 answer, anslen);
248 if (ret > 0 || trailing_dot)
249 return (ret);
250 if (errno == ECONNREFUSED) {
251 RES_SET_H_ERRNO(statp, TRY_AGAIN);
252 return (-1);
253 }
254 switch (statp->res_h_errno) {
255 case NO_DATA:
256 case HOST_NOT_FOUND:
257 break;
258 case TRY_AGAIN:
259 if (hp->rcode == SERVFAIL)
260 break;
261 /* FALLTHROUGH */
262 default:
263 return (-1);
264 }
265 saved_herrno = statp->res_h_errno;
266 tried_as_is++;
267 }
268
269 /*
270 * We do at least one level of search if
271 * - there is no dot and RES_DEFNAME is set, or
272 * - there is at least one dot, there is no trailing dot,
273 * and RES_DNSRCH is set.
274 */
275 if ((!dots && (statp->options & RES_DEFNAMES) != 0U) ||
276 (dots && !trailing_dot && (statp->options & RES_DNSRCH) != 0U)) {
277 int done = 0;
278
279 for (domain = (const char * const *)statp->dnsrch;
280 *domain && !done;
281 domain++) {
282 searched = 1;
283
284 if (domain[0][0] == '\0' ||
285 (domain[0][0] == '.' && domain[0][1] == '\0'))
286 root_on_list++;
287
288 if (root_on_list && tried_as_is)
289 continue;
290
291 ret = res_nquerydomain(statp, name, *domain,
292 class, type,
293 answer, anslen);
294 if (ret > 0)
295 return (ret);
296
297 /*
298 * If no server present, give up.
299 * If name isn't found in this domain,
300 * keep trying higher domains in the search list
301 * (if that's enabled).
302 * On a NO_DATA error, keep trying, otherwise
303 * a wildcard entry of another type could keep us
304 * from finding this entry higher in the domain.
305 * If we get some other error (negative answer or
306 * server failure), then stop searching up,
307 * but try the input name below in case it's
308 * fully-qualified.
309 */
310 if (errno == ECONNREFUSED) {
311 RES_SET_H_ERRNO(statp, TRY_AGAIN);
312 return (-1);
313 }
314
315 switch (statp->res_h_errno) {
316 case NO_DATA:
317 got_nodata++;
318 /* FALLTHROUGH */
319 case HOST_NOT_FOUND:
320 /* keep trying */
321 break;
322 case TRY_AGAIN:
323 /*
324 * This can occur due to a server failure
325 * (that is, all listed servers have failed),
326 * or all listed servers have timed out.
327 * ((HEADER *)answer)->rcode may not be set
328 * to SERVFAIL in the case of a timeout.
329 *
330 * Either way we must return TRY_AGAIN in
331 * order to avoid non-deterministic
332 * return codes.
333 * For example, loaded name servers or races
334 * against network startup/validation (dhcp,
335 * ppp, etc) can cause the search to timeout
336 * on one search element, e.g. 'fu.bar.com',
337 * and return a definitive failure on the
338 * next search element, e.g. 'fu.'.
339 */
340 got_servfail++;
341 if (hp->rcode == SERVFAIL) {
342 /* try next search element, if any */
343 break;
344 }
345 /* FALLTHROUGH */
346 default:
347 /* anything else implies that we're done */
348 done++;
349 }
350
351 /* if we got here for some reason other than DNSRCH,
352 * we only wanted one iteration of the loop, so stop.
353 */
354 if ((statp->options & RES_DNSRCH) == 0U)
355 done++;
356 }
357 }
358
359 switch (statp->res_h_errno) {
360 case NO_DATA:
361 case HOST_NOT_FOUND:
362 break;
363 case TRY_AGAIN:
364 if (hp->rcode == SERVFAIL)
365 break;
366 /* FALLTHROUGH */
367 default:
368 goto giveup;
369 }
370
371 /*
372 * If the query has not already been tried as is then try it
373 * unless RES_NOTLDQUERY is set and there were no dots.
374 */
375 if ((dots || !searched || (statp->options & RES_NOTLDQUERY) == 0U) &&
376 !(tried_as_is || root_on_list)) {
377 ret = res_nquerydomain(statp, name, NULL, class, type,
378 answer, anslen);
379 if (ret > 0)
380 return (ret);
381 }
382
383 /* if we got here, we didn't satisfy the search.
384 * if we did an initial full query, return that query's H_ERRNO
385 * (note that we wouldn't be here if that query had succeeded).
386 * else if we ever got a nodata, send that back as the reason.
387 * else send back meaningless H_ERRNO, that being the one from
388 * the last DNSRCH we did.
389 */
390giveup:
391 if (saved_herrno != -1)
392 RES_SET_H_ERRNO(statp, saved_herrno);
393 else if (got_nodata)
394 RES_SET_H_ERRNO(statp, NO_DATA);
395 else if (got_servfail)
396 RES_SET_H_ERRNO(statp, TRY_AGAIN);
397 return (-1);
398}
399
400/*%
401 * Perform a call on res_query on the concatenation of name and domain,
402 * removing a trailing dot from name if domain is NULL.
403 */
404int
405res_nquerydomain(res_state statp,
406 const char *name,
407 const char *domain,
408 int class, int type, /*%< class and type of query */
409 u_char *answer, /*%< buffer to put answer */
410 int anslen) /*%< size of answer */
411{
412 char nbuf[MAXDNAME];
413 const char *longname = nbuf;
414 int n, d;
415
416#ifdef DEBUG
417 if (statp->options & RES_DEBUG)
418 printf(";; res_nquerydomain(%s, %s, %d, %d)\n",
419 name, domain?domain:"<Nil>", class, type);
420#endif
421 if (domain == NULL) {
422 /*
423 * Check for trailing '.';
424 * copy without '.' if present.
425 */
426 n = strlen(name);
427 if (n >= MAXDNAME) {
428 RES_SET_H_ERRNO(statp, NO_RECOVERY);
429 return (-1);
430 }
431 n--;
432 if (n >= 0 && name[n] == '.') {
433 strncpy(nbuf, name, n);
434 nbuf[n] = '\0';
435 } else
436 longname = name;
437 } else {
438 n = strlen(name);
439 d = strlen(domain);
440 if (n + d + 1 >= MAXDNAME) {
441 RES_SET_H_ERRNO(statp, NO_RECOVERY);
442 return (-1);
443 }
444 sprintf(nbuf, "%s.%s", name, domain);
445 }
446 return (res_nquery(statp, longname, class, type, answer, anslen));
447}
448
449const char *
450res_hostalias(const res_state statp, const char *name, char *dst, size_t siz) {
451 char *file, *cp1, *cp2;
452 char buf[BUFSIZ];
453 FILE *fp;
454
455 if (statp->options & RES_NOALIASES)
456 return (NULL);
457 if (issetugid())
458 return (NULL);
459 file = getenv("HOSTALIASES");
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