2 * Copyright (c) 1988, 1993
3 * The Regents of the University of California. All rights reserved.
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
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.
17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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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
31 * Portions Copyright (c) 1993 by Digital Equipment Corporation.
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.
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
51 * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
52 * Portions Copyright (c) 1996-1999 by Internet Software Consortium.
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.
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.
67 #if defined(LIBC_SCCS) && !defined(lint)
68 static const char sccsid[] = "@(#)res_query.c 8.1 (Berkeley) 6/4/93";
69 static const char rcsid[] = "$Id: res_query.c,v 1.7.18.1 2005/04/27 05:01:11 sra Exp $";
70 #endif /* LIBC_SCCS and not lint */
71 #include <sys/cdefs.h>
72 __FBSDID("$FreeBSD$");
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>
88 #include "port_after.h"
90 /* Options. Leave them on. */
94 #define MAXPACKET PACKETSZ
96 #define MAXPACKET 1024
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.
107 * Caller must parse answer and determine whether it answers the question.
110 res_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 */
116 u_char buf[MAXPACKET];
117 HEADER *hp = (HEADER *) answer;
121 oflags = statp->_flags;
124 hp->rcode = NOERROR; /*%< default */
126 if (statp->options & RES_DEBUG)
127 printf(";; res_query(%s, %d, %d)\n", name, class, type);
130 n = res_nmkquery(statp, QUERY, name, class, type, NULL, 0, NULL,
133 if (n > 0 && (statp->_flags & RES_F_EDNS0ERR) == 0 &&
134 (statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0U)
135 n = res_nopt(statp, n, buf, sizeof(buf), anslen);
139 if (statp->options & RES_DEBUG)
140 printf(";; res_query: mkquery failed\n");
142 RES_SET_H_ERRNO(statp, NO_RECOVERY);
145 n = res_nsend(statp, buf, n, answer, anslen);
148 /* if the query choked with EDNS0, retry without EDNS0 */
149 if ((statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0U &&
150 ((oflags ^ statp->_flags) & RES_F_EDNS0ERR) != 0) {
151 statp->_flags |= RES_F_EDNS0ERR;
152 if (statp->options & RES_DEBUG)
153 printf(";; res_nquery: retry without EDNS0\n");
158 if (statp->options & RES_DEBUG)
159 printf(";; res_query: send error\n");
161 RES_SET_H_ERRNO(statp, TRY_AGAIN);
165 if (hp->rcode != NOERROR || ntohs(hp->ancount) == 0) {
167 if (statp->options & RES_DEBUG)
168 printf(";; rcode = (%s), counts = an:%d ns:%d ar:%d\n",
176 RES_SET_H_ERRNO(statp, HOST_NOT_FOUND);
179 RES_SET_H_ERRNO(statp, TRY_AGAIN);
182 RES_SET_H_ERRNO(statp, NO_DATA);
188 RES_SET_H_ERRNO(statp, NO_RECOVERY);
197 * Formulate a normal query, send, and retrieve answer in supplied buffer.
198 * Return the size of the response on success, -1 on error.
199 * If enabled, implement search rules until answer or unrecoverable failure
200 * is detected. Error code, if any, is left in H_ERRNO.
203 res_nsearch(res_state statp,
204 const char *name, /*%< domain name */
205 int class, int type, /*%< class and type of query */
206 u_char *answer, /*%< buffer to put answer */
207 int anslen) /*%< size of answer */
209 const char *cp, * const *domain;
210 HEADER *hp = (HEADER *) answer;
211 char tmp[NS_MAXDNAME];
213 int trailing_dot, ret, saved_herrno;
214 int got_nodata = 0, got_servfail = 0, root_on_list = 0;
219 RES_SET_H_ERRNO(statp, HOST_NOT_FOUND); /*%< True if we never query. */
221 for (cp = name; *cp != '\0'; cp++)
222 dots += (*cp == '.');
224 if (cp > name && *--cp == '.')
227 /* If there aren't any dots, it could be a user-level alias. */
228 if (!dots && (cp = res_hostalias(statp, name, tmp, sizeof tmp))!= NULL)
229 return (res_nquery(statp, cp, class, type, answer, anslen));
232 * If there are enough dots in the name, let's just give it a
233 * try 'as is'. The threshold can be set with the "ndots" option.
234 * Also, query 'as is', if there is a trailing dot in the name.
237 if (dots >= statp->ndots || trailing_dot) {
238 ret = res_nquerydomain(statp, name, NULL, class, type,
240 if (ret > 0 || trailing_dot)
242 if (errno == ECONNREFUSED) {
243 RES_SET_H_ERRNO(statp, TRY_AGAIN);
246 switch (statp->res_h_errno) {
251 if (hp->rcode == SERVFAIL)
257 saved_herrno = statp->res_h_errno;
262 * We do at least one level of search if
263 * - there is no dot and RES_DEFNAME is set, or
264 * - there is at least one dot, there is no trailing dot,
265 * and RES_DNSRCH is set.
267 if ((!dots && (statp->options & RES_DEFNAMES) != 0U) ||
268 (dots && !trailing_dot && (statp->options & RES_DNSRCH) != 0U)) {
271 for (domain = (const char * const *)statp->dnsrch;
276 if (domain[0][0] == '\0' ||
277 (domain[0][0] == '.' && domain[0][1] == '\0'))
280 if (root_on_list && tried_as_is)
283 ret = res_nquerydomain(statp, name, *domain,
290 * If no server present, give up.
291 * If name isn't found in this domain,
292 * keep trying higher domains in the search list
293 * (if that's enabled).
294 * On a NO_DATA error, keep trying, otherwise
295 * a wildcard entry of another type could keep us
296 * from finding this entry higher in the domain.
297 * If we get some other error (negative answer or
298 * server failure), then stop searching up,
299 * but try the input name below in case it's
302 if (errno == ECONNREFUSED) {
303 RES_SET_H_ERRNO(statp, TRY_AGAIN);
307 switch (statp->res_h_errno) {
316 * This can occur due to a server failure
317 * (that is, all listed servers have failed),
318 * or all listed servers have timed out.
319 * ((HEADER *)answer)->rcode may not be set
320 * to SERVFAIL in the case of a timeout.
322 * Either way we must return TRY_AGAIN in
323 * order to avoid non-deterministic
325 * For example, loaded name servers or races
326 * against network startup/validation (dhcp,
327 * ppp, etc) can cause the search to timeout
328 * on one search element, e.g. 'fu.bar.com',
329 * and return a definitive failure on the
330 * next search element, e.g. 'fu.'.
333 if (hp->rcode == SERVFAIL) {
334 /* try next search element, if any */
339 /* anything else implies that we're done */
343 /* if we got here for some reason other than DNSRCH,
344 * we only wanted one iteration of the loop, so stop.
346 if ((statp->options & RES_DNSRCH) == 0U)
351 switch (statp->res_h_errno) {
356 if (hp->rcode == SERVFAIL)
364 * If the query has not already been tried as is then try it
365 * unless RES_NOTLDQUERY is set and there were no dots.
367 if ((dots || !searched || (statp->options & RES_NOTLDQUERY) == 0U) &&
368 !(tried_as_is || root_on_list)) {
369 ret = res_nquerydomain(statp, name, NULL, class, type,
375 /* if we got here, we didn't satisfy the search.
376 * if we did an initial full query, return that query's H_ERRNO
377 * (note that we wouldn't be here if that query had succeeded).
378 * else if we ever got a nodata, send that back as the reason.
379 * else send back meaningless H_ERRNO, that being the one from
380 * the last DNSRCH we did.
383 if (saved_herrno != -1)
384 RES_SET_H_ERRNO(statp, saved_herrno);
386 RES_SET_H_ERRNO(statp, NO_DATA);
387 else if (got_servfail)
388 RES_SET_H_ERRNO(statp, TRY_AGAIN);
393 * Perform a call on res_query on the concatenation of name and domain,
394 * removing a trailing dot from name if domain is NULL.
397 res_nquerydomain(res_state statp,
400 int class, int type, /*%< class and type of query */
401 u_char *answer, /*%< buffer to put answer */
402 int anslen) /*%< size of answer */
405 const char *longname = nbuf;
409 if (statp->options & RES_DEBUG)
410 printf(";; res_nquerydomain(%s, %s, %d, %d)\n",
411 name, domain?domain:"<Nil>", class, type);
413 if (domain == NULL) {
415 * Check for trailing '.';
416 * copy without '.' if present.
420 RES_SET_H_ERRNO(statp, NO_RECOVERY);
424 if (n >= 0 && name[n] == '.') {
425 strncpy(nbuf, name, n);
432 if (n + d + 1 >= MAXDNAME) {
433 RES_SET_H_ERRNO(statp, NO_RECOVERY);
436 sprintf(nbuf, "%s.%s", name, domain);
438 return (res_nquery(statp, longname, class, type, answer, anslen));
442 res_hostalias(const res_state statp, const char *name, char *dst, size_t siz) {
443 char *file, *cp1, *cp2;
447 if (statp->options & RES_NOALIASES)
451 file = getenv("HOSTALIASES");
452 if (file == NULL || (fp = fopen(file, "r")) == NULL)
455 buf[sizeof(buf) - 1] = '\0';
456 while (fgets(buf, sizeof(buf), fp)) {
457 for (cp1 = buf; *cp1 && !isspace((unsigned char)*cp1); ++cp1)
462 if (ns_samename(buf, name) == 1) {
463 while (isspace((unsigned char)*++cp1))
467 for (cp2 = cp1 + 1; *cp2 &&
468 !isspace((unsigned char)*cp2); ++cp2)
471 strncpy(dst, cp1, siz - 1);