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. 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
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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
39 * copyright notice and this permission notice appear in all copies, and that
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
47 * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
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 * Portions Copyright (c) 1996 by Internet Software Consortium.
57 * Permission to use, copy, modify, and distribute this software for any
58 * purpose with or without fee is hereby granted, provided that the above
59 * copyright notice and this permission notice appear in all copies.
61 * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
62 * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
63 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
64 * CONSORTIUM 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
71 #if defined(LIBC_SCCS) && !defined(lint)
72 static char sccsid[] = "@(#)res_query.c 8.1 (Berkeley) 6/4/93";
73 static char orig_rcsid = "From: Id: res_query.c,v 8.14 1997/06/09 17:47:05 halley Exp $";
74 static char rcsid[] = "$Id: res_query.c,v 1.16 1998/06/11 09:03:00 peter Exp $";
75 #endif /* LIBC_SCCS and not lint */
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>
90 #include "res_config.h"
93 #define MAXPACKET PACKETSZ
95 #define MAXPACKET 1024
99 * Formulate a normal query, send, and await answer.
100 * Returned answer is placed in supplied buffer "answer".
101 * Perform preliminary check of answer, returning success only
102 * if no error is indicated and the answer count is nonzero.
103 * Return the size of the response on success, -1 on error.
104 * Error number is left in h_errno.
106 * Caller must parse answer and determine whether it answers the question.
109 res_query(name, class, type, answer, anslen)
110 const char *name; /* domain name */
111 int class, type; /* class and type of query */
112 u_char *answer; /* buffer to put answer */
113 int anslen; /* size of answer buffer */
115 u_char buf[MAXPACKET];
116 HEADER *hp = (HEADER *) answer;
119 hp->rcode = NOERROR; /* default */
121 if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
122 h_errno = NETDB_INTERNAL;
126 if (_res.options & RES_DEBUG)
127 printf(";; res_query(%s, %d, %d)\n", name, class, type);
130 n = res_mkquery(QUERY, name, class, type, NULL, 0, NULL,
134 if (_res.options & RES_DEBUG)
135 printf(";; res_query: mkquery failed\n");
137 h_errno = NO_RECOVERY;
140 n = res_send(buf, n, answer, anslen);
143 if (_res.options & RES_DEBUG)
144 printf(";; res_query: send error\n");
150 if (hp->rcode != NOERROR || ntohs(hp->ancount) == 0) {
152 if (_res.options & RES_DEBUG)
153 printf(";; rcode = %d, ancount=%d\n", hp->rcode,
158 h_errno = HOST_NOT_FOUND;
170 h_errno = NO_RECOVERY;
179 * Formulate a normal query, send, and retrieve answer in supplied buffer.
180 * Return the size of the response on success, -1 on error.
181 * If enabled, implement search rules until answer or unrecoverable failure
182 * is detected. Error code, if any, is left in h_errno.
185 res_search(name, class, type, answer, anslen)
186 const char *name; /* domain name */
187 int class, type; /* class and type of query */
188 u_char *answer; /* buffer to put answer */
189 int anslen; /* size of answer */
191 const char *cp, * const *domain;
192 HEADER *hp = (HEADER *) answer;
194 int trailing_dot, ret, saved_herrno;
195 int got_nodata = 0, got_servfail = 0, tried_as_is = 0;
197 if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
198 h_errno = NETDB_INTERNAL;
202 h_errno = HOST_NOT_FOUND; /* default, if we never query */
204 for (cp = name; *cp; cp++)
205 dots += (*cp == '.');
207 if (cp > name && *--cp == '.')
210 /* If there aren't any dots, it could be a user-level alias */
211 if (!dots && (cp = hostalias(name)) != NULL)
212 return (res_query(cp, class, type, answer, anslen));
215 * If there are dots in the name already, let's just give it a try
216 * 'as is'. The threshold can be set with the "ndots" option.
219 if (dots >= _res.ndots) {
220 ret = res_querydomain(name, NULL, class, type, answer, anslen);
223 saved_herrno = h_errno;
228 * We do at least one level of search if
229 * - there is no dot and RES_DEFNAME is set, or
230 * - there is at least one dot, there is no trailing dot,
231 * and RES_DNSRCH is set.
233 if ((!dots && (_res.options & RES_DEFNAMES)) ||
234 (dots && !trailing_dot && (_res.options & RES_DNSRCH))) {
237 for (domain = (const char * const *)_res.dnsrch;
241 ret = res_querydomain(name, *domain, class, type,
247 * If no server present, give up.
248 * If name isn't found in this domain,
249 * keep trying higher domains in the search list
250 * (if that's enabled).
251 * On a NO_DATA error, keep trying, otherwise
252 * a wildcard entry of another type could keep us
253 * from finding this entry higher in the domain.
254 * If we get some other error (negative answer or
255 * server failure), then stop searching up,
256 * but try the input name below in case it's
259 if (errno == ECONNREFUSED) {
272 if (hp->rcode == SERVFAIL) {
273 /* try next search element, if any */
279 /* anything else implies that we're done */
283 /* if we got here for some reason other than DNSRCH,
284 * we only wanted one iteration of the loop, so stop.
286 if (!(_res.options & RES_DNSRCH))
292 * If we have not already tried the name "as is", do that now.
293 * note that we do this regardless of how many dots were in the
294 * name or whether it ends with a dot unless NOTLDQUERY is set.
296 if (!tried_as_is && (dots || !(_res.options & RES_NOTLDQUERY))) {
297 ret = res_querydomain(name, NULL, class, type, answer, anslen);
302 /* if we got here, we didn't satisfy the search.
303 * if we did an initial full query, return that query's h_errno
304 * (note that we wouldn't be here if that query had succeeded).
305 * else if we ever got a nodata, send that back as the reason.
306 * else send back meaningless h_errno, that being the one from
307 * the last DNSRCH we did.
309 if (saved_herrno != -1)
310 h_errno = saved_herrno;
313 else if (got_servfail)
319 * Perform a call on res_query on the concatenation of name and domain,
320 * removing a trailing dot from name if domain is NULL.
323 res_querydomain(name, domain, class, type, answer, anslen)
324 const char *name, *domain;
325 int class, type; /* class and type of query */
326 u_char *answer; /* buffer to put answer */
327 int anslen; /* size of answer */
330 const char *longname = nbuf;
333 if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
334 h_errno = NETDB_INTERNAL;
338 if (_res.options & RES_DEBUG)
339 printf(";; res_querydomain(%s, %s, %d, %d)\n",
340 name, domain?domain:"<Nil>", class, type);
342 if (domain == NULL) {
344 * Check for trailing '.';
345 * copy without '.' if present.
349 h_errno = NO_RECOVERY;
353 if (n >= 0 && name[n] == '.') {
354 strncpy(nbuf, name, n);
361 if (n + d + 1 >= MAXDNAME) {
362 h_errno = NO_RECOVERY;
365 sprintf(nbuf, "%s.%s", name, domain);
367 return (res_query(longname, class, type, answer, anslen));
374 register char *cp1, *cp2;
378 static char abuf[MAXDNAME];
380 if (_res.options & RES_NOALIASES)
384 file = getenv("HOSTALIASES");
385 if (file == NULL || (fp = fopen(file, "r")) == NULL)
388 buf[sizeof(buf) - 1] = '\0';
389 while (fgets(buf, sizeof(buf), fp)) {
390 for (cp1 = buf; *cp1 && !isspace(*cp1); ++cp1)
395 if (!strcasecmp(buf, name)) {
396 while (isspace(*++cp1))
400 for (cp2 = cp1 + 1; *cp2 && !isspace(*cp2); ++cp2)
402 abuf[sizeof(abuf) - 1] = *cp2 = '\0';
403 strncpy(abuf, cp1, sizeof(abuf) - 1);
413 * Weak aliases for applications that use certain private entry points,
414 * and fail to include <resolv.h>.
417 __weak_reference(__res_query, res_query);
419 __weak_reference(__res_search, res_search);
420 #undef res_querydomain
421 __weak_reference(__res_querydomain, res_querydomain);