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
24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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 #endif /* LIBC_SCCS and not lint */
75 #include <sys/cdefs.h>
76 #include <sys/types.h>
78 #include <sys/types.h>
79 #include <sys/param.h>
80 #include <netinet/in.h>
81 #include <arpa/inet.h>
82 #include <arpa/nameser.h>
91 #include "res_config.h"
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_query(name, class, type, answer, anslen)
111 const char *name; /* domain name */
112 int class, 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;
120 hp->rcode = NOERROR; /* default */
122 if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
123 h_errno = NETDB_INTERNAL;
127 if (_res.options & RES_DEBUG)
128 printf(";; res_query(%s, %d, %d)\n", name, class, type);
131 n = res_mkquery(QUERY, name, class, type, NULL, 0, NULL,
133 if (n > 0 && (_res.options & RES_USE_EDNS0) != 0)
134 n = res_opt(n, buf, sizeof(buf), anslen);
137 if (_res.options & RES_DEBUG)
138 printf(";; res_query: mkquery failed\n");
140 h_errno = NO_RECOVERY;
143 n = res_send(buf, n, answer, anslen);
146 if (_res.options & RES_DEBUG)
147 printf(";; res_query: send error\n");
153 if (hp->rcode != NOERROR || ntohs(hp->ancount) == 0) {
155 if (_res.options & RES_DEBUG)
156 printf(";; rcode = %d, ancount=%d\n", hp->rcode,
161 h_errno = HOST_NOT_FOUND;
173 h_errno = NO_RECOVERY;
182 * Formulate a normal query, send, and retrieve answer in supplied buffer.
183 * Return the size of the response on success, -1 on error.
184 * If enabled, implement search rules until answer or unrecoverable failure
185 * is detected. Error code, if any, is left in h_errno.
188 res_search(name, class, type, answer, anslen)
189 const char *name; /* domain name */
190 int class, type; /* class and type of query */
191 u_char *answer; /* buffer to put answer */
192 int anslen; /* size of answer */
194 const char *cp, * const *domain;
195 HEADER *hp = (HEADER *) answer;
197 int trailing_dot, ret, saved_herrno;
198 int got_nodata = 0, got_servfail = 0, tried_as_is = 0;
200 if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
201 h_errno = NETDB_INTERNAL;
205 h_errno = HOST_NOT_FOUND; /* default, if we never query */
207 for (cp = name; *cp; cp++)
208 dots += (*cp == '.');
210 if (cp > name && *--cp == '.')
213 /* If there aren't any dots, it could be a user-level alias */
214 if (!dots && (cp = hostalias(name)) != NULL)
215 return (res_query(cp, class, type, answer, anslen));
218 * If there are dots in the name already, let's just give it a try
219 * 'as is'. The threshold can be set with the "ndots" option.
222 if (dots >= _res.ndots) {
223 ret = res_querydomain(name, NULL, class, type, answer, anslen);
226 saved_herrno = h_errno;
231 * We do at least one level of search if
232 * - there is no dot and RES_DEFNAME is set, or
233 * - there is at least one dot, there is no trailing dot,
234 * and RES_DNSRCH is set.
236 if ((!dots && (_res.options & RES_DEFNAMES)) ||
237 (dots && !trailing_dot && (_res.options & RES_DNSRCH))) {
240 for (domain = (const char * const *)_res.dnsrch;
244 ret = res_querydomain(name, *domain, class, type,
250 * If no server present, give up.
251 * If name isn't found in this domain,
252 * keep trying higher domains in the search list
253 * (if that's enabled).
254 * On a NO_DATA error, keep trying, otherwise
255 * a wildcard entry of another type could keep us
256 * from finding this entry higher in the domain.
257 * If we get some other error (negative answer or
258 * server failure), then stop searching up,
259 * but try the input name below in case it's
262 if (errno == ECONNREFUSED) {
275 if (hp->rcode == SERVFAIL) {
276 /* try next search element, if any */
282 /* anything else implies that we're done */
286 /* if we got here for some reason other than DNSRCH,
287 * we only wanted one iteration of the loop, so stop.
289 if (!(_res.options & RES_DNSRCH))
295 * If we have not already tried the name "as is", do that now.
296 * note that we do this regardless of how many dots were in the
297 * name or whether it ends with a dot unless NOTLDQUERY is set.
299 if (!tried_as_is && (dots || !(_res.options & RES_NOTLDQUERY))) {
300 ret = res_querydomain(name, NULL, class, type, answer, anslen);
305 /* if we got here, we didn't satisfy the search.
306 * if we did an initial full query, return that query's h_errno
307 * (note that we wouldn't be here if that query had succeeded).
308 * else if we ever got a nodata, send that back as the reason.
309 * else send back meaningless h_errno, that being the one from
310 * the last DNSRCH we did.
312 if (saved_herrno != -1)
313 h_errno = saved_herrno;
316 else if (got_servfail)
322 * Perform a call on res_query on the concatenation of name and domain,
323 * removing a trailing dot from name if domain is NULL.
326 res_querydomain(name, domain, class, type, answer, anslen)
327 const char *name, *domain;
328 int class, type; /* class and type of query */
329 u_char *answer; /* buffer to put answer */
330 int anslen; /* size of answer */
333 const char *longname = nbuf;
336 if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
337 h_errno = NETDB_INTERNAL;
341 if (_res.options & RES_DEBUG)
342 printf(";; res_querydomain(%s, %s, %d, %d)\n",
343 name, domain?domain:"<Nil>", class, type);
345 if (domain == NULL) {
347 * Check for trailing '.';
348 * copy without '.' if present.
352 h_errno = NO_RECOVERY;
356 if (n >= 0 && name[n] == '.') {
357 strncpy(nbuf, name, n);
364 if (n + d + 1 >= MAXDNAME) {
365 h_errno = NO_RECOVERY;
368 sprintf(nbuf, "%s.%s", name, domain);
370 return (res_query(longname, class, type, answer, anslen));
381 static char abuf[MAXDNAME];
383 if (_res.options & RES_NOALIASES)
387 file = getenv("HOSTALIASES");
388 if (file == NULL || (fp = fopen(file, "r")) == NULL)
391 buf[sizeof(buf) - 1] = '\0';
392 while (fgets(buf, sizeof(buf), fp)) {
393 for (cp1 = buf; *cp1 && !isspace((unsigned char)*cp1); ++cp1)
398 if (!strcasecmp(buf, name)) {
399 while (isspace((unsigned char)*++cp1))
403 for (cp2 = cp1 + 1; *cp2 && !isspace((unsigned char)*cp2); ++cp2)
405 abuf[sizeof(abuf) - 1] = *cp2 = '\0';
406 strncpy(abuf, cp1, sizeof(abuf) - 1);
416 * Weak aliases for applications that use certain private entry points,
417 * and fail to include <resolv.h>.
420 __weak_reference(__res_query, res_query);
422 __weak_reference(__res_search, res_search);
423 #undef res_querydomain
424 __weak_reference(__res_querydomain, res_querydomain);