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 * 3. 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
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
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 1.8.672.2 2008/04/03 10:49:22 marka Exp $";
70 #endif /* LIBC_SCCS and not lint */
72 #include "port_before.h"
73 #include <sys/types.h>
74 #include <sys/param.h>
75 #include <netinet/in.h>
76 #include <arpa/inet.h>
77 #include <arpa/nameser.h>
85 #include "port_after.h"
87 /* Options. Leave them on. */
91 #define MAXPACKET PACKETSZ
93 #define MAXPACKET 1024
97 * Formulate a normal query, send, and await answer.
98 * Returned answer is placed in supplied buffer "answer".
99 * Perform preliminary check of answer, returning success only
100 * if no error is indicated and the answer count is nonzero.
101 * Return the size of the response on success, -1 on error.
102 * Error number is left in H_ERRNO.
104 * Caller must parse answer and determine whether it answers the question.
107 res_nquery(res_state statp,
108 const char *name, /*%< domain name */
109 int class, int type, /*%< class and type of query */
110 u_char *answer, /*%< buffer to put answer */
111 int anslen) /*%< size of answer buffer */
113 u_char buf[MAXPACKET];
114 HEADER *hp = (HEADER *) answer;
119 oflags = statp->_flags;
122 hp->rcode = NOERROR; /*%< default */
124 if (statp->options & RES_DEBUG)
125 printf(";; res_query(%s, %d, %d)\n", name, class, type);
128 n = res_nmkquery(statp, QUERY, name, class, type, NULL, 0, NULL,
131 if (n > 0 && (statp->_flags & RES_F_EDNS0ERR) == 0 &&
132 (statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC|RES_NSID))) {
133 n = res_nopt(statp, n, buf, sizeof(buf), anslen);
135 if (n > 0 && (statp->options & RES_NSID) != 0U) {
136 n = res_nopt_rdata(statp, n, buf, sizeof(buf), rdata,
137 NS_OPT_NSID, 0, NULL);
143 if (statp->options & RES_DEBUG)
144 printf(";; res_query: mkquery failed\n");
146 RES_SET_H_ERRNO(statp, NO_RECOVERY);
150 n = res_nsend(statp, buf, n, answer, anslen);
153 /* if the query choked with EDNS0, retry without EDNS0 */
154 if ((statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0U &&
155 ((oflags ^ statp->_flags) & RES_F_EDNS0ERR) != 0) {
156 statp->_flags |= RES_F_EDNS0ERR;
157 if (statp->options & RES_DEBUG)
158 printf(";; res_nquery: retry without EDNS0\n");
163 if (statp->options & RES_DEBUG)
164 printf(";; res_query: send error\n");
166 RES_SET_H_ERRNO(statp, TRY_AGAIN);
170 if (hp->rcode != NOERROR || ntohs(hp->ancount) == 0) {
172 if (statp->options & RES_DEBUG)
173 printf(";; rcode = (%s), counts = an:%d ns:%d ar:%d\n",
181 RES_SET_H_ERRNO(statp, HOST_NOT_FOUND);
184 RES_SET_H_ERRNO(statp, TRY_AGAIN);
187 RES_SET_H_ERRNO(statp, NO_DATA);
193 RES_SET_H_ERRNO(statp, NO_RECOVERY);
202 * Formulate a normal query, send, and retrieve answer in supplied buffer.
203 * Return the size of the response on success, -1 on error.
204 * If enabled, implement search rules until answer or unrecoverable failure
205 * is detected. Error code, if any, is left in H_ERRNO.
208 res_nsearch(res_state statp,
209 const char *name, /*%< domain name */
210 int class, int type, /*%< class and type of query */
211 u_char *answer, /*%< buffer to put answer */
212 int anslen) /*%< size of answer */
214 const char *cp, * const *domain;
215 HEADER *hp = (HEADER *) answer;
216 char tmp[NS_MAXDNAME];
218 int trailing_dot, ret, saved_herrno;
219 int got_nodata = 0, got_servfail = 0, root_on_list = 0;
224 RES_SET_H_ERRNO(statp, HOST_NOT_FOUND); /*%< True if we never query. */
226 for (cp = name; *cp != '\0'; cp++)
227 dots += (*cp == '.');
229 if (cp > name && *--cp == '.')
232 /* If there aren't any dots, it could be a user-level alias. */
233 if (!dots && (cp = res_hostalias(statp, name, tmp, sizeof tmp))!= NULL)
234 return (res_nquery(statp, cp, class, type, answer, anslen));
237 * If there are enough dots in the name, let's just give it a
238 * try 'as is'. The threshold can be set with the "ndots" option.
239 * Also, query 'as is', if there is a trailing dot in the name.
242 if (dots >= statp->ndots || trailing_dot) {
243 ret = res_nquerydomain(statp, name, NULL, class, type,
245 if (ret > 0 || trailing_dot)
247 saved_herrno = statp->res_h_errno;
252 * We do at least one level of search if
253 * - there is no dot and RES_DEFNAME is set, or
254 * - there is at least one dot, there is no trailing dot,
255 * and RES_DNSRCH is set.
257 if ((!dots && (statp->options & RES_DEFNAMES) != 0U) ||
258 (dots && !trailing_dot && (statp->options & RES_DNSRCH) != 0U)) {
261 for (domain = (const char * const *)statp->dnsrch;
266 if (domain[0][0] == '\0' ||
267 (domain[0][0] == '.' && domain[0][1] == '\0'))
270 ret = res_nquerydomain(statp, name, *domain,
277 * If no server present, give up.
278 * If name isn't found in this domain,
279 * keep trying higher domains in the search list
280 * (if that's enabled).
281 * On a NO_DATA error, keep trying, otherwise
282 * a wildcard entry of another type could keep us
283 * from finding this entry higher in the domain.
284 * If we get some other error (negative answer or
285 * server failure), then stop searching up,
286 * but try the input name below in case it's
289 if (errno == ECONNREFUSED) {
290 RES_SET_H_ERRNO(statp, TRY_AGAIN);
294 switch (statp->res_h_errno) {
302 if (hp->rcode == SERVFAIL) {
303 /* try next search element, if any */
309 /* anything else implies that we're done */
313 /* if we got here for some reason other than DNSRCH,
314 * we only wanted one iteration of the loop, so stop.
316 if ((statp->options & RES_DNSRCH) == 0U)
322 * If the query has not already been tried as is then try it
323 * unless RES_NOTLDQUERY is set and there were no dots.
325 if ((dots || !searched || (statp->options & RES_NOTLDQUERY) == 0U) &&
326 !(tried_as_is || root_on_list)) {
327 ret = res_nquerydomain(statp, name, NULL, class, type,
333 /* if we got here, we didn't satisfy the search.
334 * if we did an initial full query, return that query's H_ERRNO
335 * (note that we wouldn't be here if that query had succeeded).
336 * else if we ever got a nodata, send that back as the reason.
337 * else send back meaningless H_ERRNO, that being the one from
338 * the last DNSRCH we did.
340 if (saved_herrno != -1)
341 RES_SET_H_ERRNO(statp, saved_herrno);
343 RES_SET_H_ERRNO(statp, NO_DATA);
344 else if (got_servfail)
345 RES_SET_H_ERRNO(statp, TRY_AGAIN);
350 * Perform a call on res_query on the concatenation of name and domain,
351 * removing a trailing dot from name if domain is NULL.
354 res_nquerydomain(res_state statp,
357 int class, int type, /*%< class and type of query */
358 u_char *answer, /*%< buffer to put answer */
359 int anslen) /*%< size of answer */
362 const char *longname = nbuf;
366 if (statp->options & RES_DEBUG)
367 printf(";; res_nquerydomain(%s, %s, %d, %d)\n",
368 name, domain?domain:"<Nil>", class, type);
370 if (domain == NULL) {
372 * Check for trailing '.';
373 * copy without '.' if present.
377 RES_SET_H_ERRNO(statp, NO_RECOVERY);
381 if (n >= 0 && name[n] == '.') {
382 strncpy(nbuf, name, n);
389 if (n + d + 1 >= MAXDNAME) {
390 RES_SET_H_ERRNO(statp, NO_RECOVERY);
393 sprintf(nbuf, "%s.%s", name, domain);
395 return (res_nquery(statp, longname, class, type, answer, anslen));
399 res_hostalias(const res_state statp, const char *name, char *dst, size_t siz) {
400 char *file, *cp1, *cp2;
404 if (statp->options & RES_NOALIASES)
406 file = getenv("HOSTALIASES");
407 if (file == NULL || (fp = fopen(file, "r")) == NULL)
410 buf[sizeof(buf) - 1] = '\0';
411 while (fgets(buf, sizeof(buf), fp)) {
412 for (cp1 = buf; *cp1 && !isspace((unsigned char)*cp1); ++cp1)
417 if (ns_samename(buf, name) == 1) {
418 while (isspace((unsigned char)*++cp1))
422 for (cp2 = cp1 + 1; *cp2 &&
423 !isspace((unsigned char)*cp2); ++cp2)
426 strncpy(dst, cp1, siz - 1);