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
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12 * documentation and/or other materials provided with the distribution.
13 * 3. All advertising materials mentioning features or use of this software
14 * must display the following acknowledgement:
15 * This product includes software developed by the University of
16 * California, Berkeley and its contributors.
17 * 4. Neither the name of the University nor the names of its contributors
18 * may be used to endorse or promote products derived from this software
19 * without specific prior written permission.
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
35 * Portions Copyright (c) 1993 by Digital Equipment Corporation.
37 * Permission to use, copy, modify, and distribute this software for any
38 * purpose with or without fee is hereby granted, provided that the above
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40 * the name of Digital Equipment Corporation not be used in advertising or
41 * publicity pertaining to distribution of the document or software without
42 * specific, written prior permission.
44 * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
45 * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
46 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL DIGITAL EQUIPMENT
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48 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
49 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
50 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
55 * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
56 * Portions Copyright (c) 1996-1999 by Internet Software Consortium.
58 * Permission to use, copy, modify, and distribute this software for any
59 * purpose with or without fee is hereby granted, provided that the above
60 * copyright notice and this permission notice appear in all copies.
62 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
63 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
64 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR
65 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
66 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
67 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
68 * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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 1.8.672.2 2008/04/03 10:49:22 marka Exp $";
74 #endif /* LIBC_SCCS and not lint */
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>
89 #include "port_after.h"
91 /* Options. Leave them on. */
95 #define MAXPACKET PACKETSZ
97 #define MAXPACKET 1024
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.
108 * Caller must parse answer and determine whether it answers the question.
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 */
117 u_char buf[MAXPACKET];
118 HEADER *hp = (HEADER *) answer;
123 oflags = statp->_flags;
126 hp->rcode = NOERROR; /*%< default */
128 if (statp->options & RES_DEBUG)
129 printf(";; res_query(%s, %d, %d)\n", name, class, type);
132 n = res_nmkquery(statp, QUERY, name, class, type, NULL, 0, NULL,
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);
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);
147 if (statp->options & RES_DEBUG)
148 printf(";; res_query: mkquery failed\n");
150 RES_SET_H_ERRNO(statp, NO_RECOVERY);
154 n = res_nsend(statp, buf, n, answer, anslen);
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");
167 if (statp->options & RES_DEBUG)
168 printf(";; res_query: send error\n");
170 RES_SET_H_ERRNO(statp, TRY_AGAIN);
174 if (hp->rcode != NOERROR || ntohs(hp->ancount) == 0) {
176 if (statp->options & RES_DEBUG)
177 printf(";; rcode = (%s), counts = an:%d ns:%d ar:%d\n",
185 RES_SET_H_ERRNO(statp, HOST_NOT_FOUND);
188 RES_SET_H_ERRNO(statp, TRY_AGAIN);
191 RES_SET_H_ERRNO(statp, NO_DATA);
197 RES_SET_H_ERRNO(statp, NO_RECOVERY);
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.
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 */
218 const char *cp, * const *domain;
219 HEADER *hp = (HEADER *) answer;
220 char tmp[NS_MAXDNAME];
222 int trailing_dot, ret, saved_herrno;
223 int got_nodata = 0, got_servfail = 0, root_on_list = 0;
228 RES_SET_H_ERRNO(statp, HOST_NOT_FOUND); /*%< True if we never query. */
230 for (cp = name; *cp != '\0'; cp++)
231 dots += (*cp == '.');
233 if (cp > name && *--cp == '.')
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));
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.
246 if (dots >= statp->ndots || trailing_dot) {
247 ret = res_nquerydomain(statp, name, NULL, class, type,
249 if (ret > 0 || trailing_dot)
251 saved_herrno = statp->res_h_errno;
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.
261 if ((!dots && (statp->options & RES_DEFNAMES) != 0U) ||
262 (dots && !trailing_dot && (statp->options & RES_DNSRCH) != 0U)) {
265 for (domain = (const char * const *)statp->dnsrch;
270 if (domain[0][0] == '\0' ||
271 (domain[0][0] == '.' && domain[0][1] == '\0'))
274 ret = res_nquerydomain(statp, name, *domain,
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
293 if (errno == ECONNREFUSED) {
294 RES_SET_H_ERRNO(statp, TRY_AGAIN);
298 switch (statp->res_h_errno) {
306 if (hp->rcode == SERVFAIL) {
307 /* try next search element, if any */
313 /* anything else implies that we're done */
317 /* if we got here for some reason other than DNSRCH,
318 * we only wanted one iteration of the loop, so stop.
320 if ((statp->options & RES_DNSRCH) == 0U)
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.
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,
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.
344 if (saved_herrno != -1)
345 RES_SET_H_ERRNO(statp, saved_herrno);
347 RES_SET_H_ERRNO(statp, NO_DATA);
348 else if (got_servfail)
349 RES_SET_H_ERRNO(statp, TRY_AGAIN);
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.
358 res_nquerydomain(res_state statp,
361 int class, int type, /*%< class and type of query */
362 u_char *answer, /*%< buffer to put answer */
363 int anslen) /*%< size of answer */
366 const char *longname = nbuf;
370 if (statp->options & RES_DEBUG)
371 printf(";; res_nquerydomain(%s, %s, %d, %d)\n",
372 name, domain?domain:"<Nil>", class, type);
374 if (domain == NULL) {
376 * Check for trailing '.';
377 * copy without '.' if present.
381 RES_SET_H_ERRNO(statp, NO_RECOVERY);
385 if (n >= 0 && name[n] == '.') {
386 strncpy(nbuf, name, n);
393 if (n + d + 1 >= MAXDNAME) {
394 RES_SET_H_ERRNO(statp, NO_RECOVERY);
397 sprintf(nbuf, "%s.%s", name, domain);
399 return (res_nquery(statp, longname, class, type, answer, anslen));
403 res_hostalias(const res_state statp, const char *name, char *dst, size_t siz) {
404 char *file, *cp1, *cp2;
408 if (statp->options & RES_NOALIASES)
410 file = getenv("HOSTALIASES");
411 if (file == NULL || (fp = fopen(file, "r")) == NULL)
414 buf[sizeof(buf) - 1] = '\0';
415 while (fgets(buf, sizeof(buf), fp)) {
416 for (cp1 = buf; *cp1 && !isspace((unsigned char)*cp1); ++cp1)
421 if (ns_samename(buf, name) == 1) {
422 while (isspace((unsigned char)*++cp1))
426 for (cp2 = cp1 + 1; *cp2 &&
427 !isspace((unsigned char)*cp2); ++cp2)
430 strncpy(dst, cp1, siz - 1);