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
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 * Portions Copyright (c) 1996-1999 by Internet Software Consortium.
53 * Permission to use, copy, modify, and distribute this software for any
54 * purpose with or without fee is hereby granted, provided that the above
55 * copyright notice and this permission notice appear in all copies.
57 * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
58 * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
59 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
60 * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
61 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
62 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
63 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
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[] = "$BINDId: res_query.c,v 8.20 2000/02/29 05:39:12 vixie Exp $";
70 #endif /* LIBC_SCCS and not lint */
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>
86 /* Options. Leave them on. */
90 #define MAXPACKET PACKETSZ
92 #define MAXPACKET 65536
95 #define QUERYSIZE (HFIXEDSZ + QFIXEDSZ + MAXCDNAME + 1)
98 __libc_res_nquerydomain(res_state statp, const char *name, const char *domain,
99 int class, int type, u_char *answer, int anslen,
103 * Formulate a normal query, send, and await answer.
104 * Returned answer is placed in supplied buffer "answer".
105 * Perform preliminary check of answer, returning success only
106 * if no error is indicated and the answer count is nonzero.
107 * Return the size of the response on success, -1 on error.
108 * Error number is left in H_ERRNO.
110 * Caller must parse answer and determine whether it answers the question.
113 __libc_res_nquery(res_state statp,
114 const char *name, /* domain name */
115 int class, int type, /* class and type of query */
116 u_char *answer, /* buffer to put answer */
117 int anslen, /* size of answer buffer */
118 u_char **answerp) /* if buffer needs to be enlarged */
121 HEADER *hp = (HEADER *) answer;
122 int n, use_malloc = 0;
123 u_int oflags = statp->_flags;
125 size_t bufsize = QUERYSIZE;
126 buf = alloca (bufsize);
129 hp->rcode = NOERROR; /* default */
132 if (statp->options & RES_DEBUG)
133 printf(";; res_query(%s, %d, %d)\n", name, class, type);
136 n = res_nmkquery(statp, QUERY, name, class, type, NULL, 0, NULL,
139 && (oflags & RES_F_EDNS0ERR) == 0
140 && (statp->options & RES_USE_EDNS0) != 0)
141 n = __res_nopt(statp, n, buf, bufsize, anslen);
142 if (__builtin_expect (n <= 0, 0) && !use_malloc) {
143 /* Retry just in case res_nmkquery failed because of too
144 short buffer. Shouldn't happen. */
146 buf = malloc (bufsize);
152 if (__builtin_expect (n <= 0, 0)) {
153 /* If the query choked with EDNS0, retry without EDNS0. */
154 if ((statp->options & RES_USE_EDNS0) != 0
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");
162 if (statp->options & RES_DEBUG)
163 printf(";; res_query: mkquery failed\n");
165 RES_SET_H_ERRNO(statp, NO_RECOVERY);
170 assert (answerp == NULL || (void *) *answerp == (void *) answer);
171 n = __libc_res_nsend(statp, buf, n, answer, anslen, answerp);
176 if (statp->options & RES_DEBUG)
177 printf(";; res_query: send error\n");
179 RES_SET_H_ERRNO(statp, TRY_AGAIN);
184 /* __libc_res_nsend might have reallocated the buffer. */
185 hp = (HEADER *) *answerp;
187 if (hp->rcode != NOERROR || ntohs(hp->ancount) == 0) {
189 if (statp->options & RES_DEBUG)
190 printf(";; rcode = %d, ancount=%d\n", hp->rcode,
195 RES_SET_H_ERRNO(statp, HOST_NOT_FOUND);
198 RES_SET_H_ERRNO(statp, TRY_AGAIN);
201 RES_SET_H_ERRNO(statp, NO_DATA);
207 RES_SET_H_ERRNO(statp, NO_RECOVERY);
214 libresolv_hidden_def (__libc_res_nquery)
217 res_nquery(res_state statp,
218 const char *name, /* domain name */
219 int class, int type, /* class and type of query */
220 u_char *answer, /* buffer to put answer */
221 int anslen) /* size of answer buffer */
223 return __libc_res_nquery(statp, name, class, type, answer, anslen,
226 libresolv_hidden_def (res_nquery)
229 * Formulate a normal query, send, and retrieve answer in supplied buffer.
230 * Return the size of the response on success, -1 on error.
231 * If enabled, implement search rules until answer or unrecoverable failure
232 * is detected. Error code, if any, is left in H_ERRNO.
235 __libc_res_nsearch(res_state statp,
236 const char *name, /* domain name */
237 int class, int type, /* class and type of query */
238 u_char *answer, /* buffer to put answer */
239 int anslen, /* size of answer */
242 const char *cp, * const *domain;
243 HEADER *hp = (HEADER *) answer;
244 char tmp[NS_MAXDNAME];
246 int trailing_dot, ret, saved_herrno;
247 int got_nodata = 0, got_servfail = 0, root_on_list = 0;
251 RES_SET_H_ERRNO(statp, HOST_NOT_FOUND); /* True if we never query. */
254 for (cp = name; *cp != '\0'; cp++)
255 dots += (*cp == '.');
257 if (cp > name && *--cp == '.')
260 /* If there aren't any dots, it could be a user-level alias. */
261 if (!dots && (cp = res_hostalias(statp, name, tmp, sizeof tmp))!= NULL)
262 return (__libc_res_nquery(statp, cp, class, type, answer,
266 if (statp->options & RES_DEBUG)
267 printf("dots=%d, statp->ndots=%d, trailing_dot=%d, name=%s\n",
268 (int)dots,(int)statp->ndots,(int)trailing_dot,name);
272 * If there are enough dots in the name, let's just give it a
273 * try 'as is'. The threshold can be set with the "ndots" option.
274 * Also, query 'as is', if there is a trailing dot in the name.
277 if (dots >= statp->ndots || trailing_dot) {
278 ret = __libc_res_nquerydomain(statp, name, NULL, class, type,
279 answer, anslen, answerp);
280 if (ret > 0 || trailing_dot)
282 saved_herrno = h_errno;
284 if (answerp && *answerp != answer) {
291 * We do at least one level of search if
292 * - there is no dot and RES_DEFNAME is set, or
293 * - there is at least one dot, there is no trailing dot,
294 * and RES_DNSRCH is set.
296 if ((!dots && (statp->options & RES_DEFNAMES) != 0) ||
297 (dots && !trailing_dot && (statp->options & RES_DNSRCH) != 0)) {
300 for (domain = (const char * const *)statp->dnsrch;
304 if (domain[0][0] == '\0' ||
305 (domain[0][0] == '.' && domain[0][1] == '\0'))
308 ret = __libc_res_nquerydomain(statp, name, *domain,
310 answer, anslen, answerp);
314 if (answerp && *answerp != answer) {
320 * If no server present, give up.
321 * If name isn't found in this domain,
322 * keep trying higher domains in the search list
323 * (if that's enabled).
324 * On a NO_DATA error, keep trying, otherwise
325 * a wildcard entry of another type could keep us
326 * from finding this entry higher in the domain.
327 * If we get some other error (negative answer or
328 * server failure), then stop searching up,
329 * but try the input name below in case it's
332 if (errno == ECONNREFUSED) {
333 RES_SET_H_ERRNO(statp, TRY_AGAIN);
337 switch (statp->res_h_errno) {
345 if (hp->rcode == SERVFAIL) {
346 /* try next search element, if any */
352 /* anything else implies that we're done */
356 /* if we got here for some reason other than DNSRCH,
357 * we only wanted one iteration of the loop, so stop.
359 if ((statp->options & RES_DNSRCH) == 0)
365 * If the name has any dots at all, and no earlier 'as-is' query
366 * for the name, and "." is not on the search list, then try an as-is
369 if (dots && !(tried_as_is || root_on_list)) {
370 ret = __libc_res_nquerydomain(statp, name, NULL, class, type,
371 answer, anslen, answerp);
376 /* if we got here, we didn't satisfy the search.
377 * if we did an initial full query, return that query's H_ERRNO
378 * (note that we wouldn't be here if that query had succeeded).
379 * else if we ever got a nodata, send that back as the reason.
380 * else send back meaningless H_ERRNO, that being the one from
381 * 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);
391 libresolv_hidden_def (__libc_res_nsearch)
394 res_nsearch(res_state statp,
395 const char *name, /* domain name */
396 int class, int type, /* class and type of query */
397 u_char *answer, /* buffer to put answer */
398 int anslen) /* size of answer */
400 return __libc_res_nsearch(statp, name, class, type, answer,
403 libresolv_hidden_def (res_nsearch)
406 * Perform a call on res_query on the concatenation of name and domain,
407 * removing a trailing dot from name if domain is NULL.
410 __libc_res_nquerydomain(res_state statp,
413 int class, int type, /* class and type of query */
414 u_char *answer, /* buffer to put answer */
415 int anslen, /* size of answer */
419 const char *longname = nbuf;
423 if (statp->options & RES_DEBUG)
424 printf(";; res_nquerydomain(%s, %s, %d, %d)\n",
425 name, domain?domain:"<Nil>", class, type);
427 if (domain == NULL) {
429 * Check for trailing '.';
430 * copy without '.' if present.
434 RES_SET_H_ERRNO(statp, NO_RECOVERY);
438 if (n >= 0 && name[n] == '.') {
439 strncpy(nbuf, name, n);
446 if (n + d + 1 >= MAXDNAME) {
447 RES_SET_H_ERRNO(statp, NO_RECOVERY);
450 sprintf(nbuf, "%s.%s", name, domain);
452 return (__libc_res_nquery(statp, longname, class, type, answer,
457 res_nquerydomain(res_state statp,
460 int class, int type, /* class and type of query */
461 u_char *answer, /* buffer to put answer */
462 int anslen) /* size of answer */
464 return __libc_res_nquerydomain(statp, name, domain, class, type,
465 answer, anslen, NULL);
467 libresolv_hidden_def (res_nquerydomain)
470 res_hostalias(const res_state statp, const char *name, char *dst, size_t siz) {
471 char *file, *cp1, *cp2;
475 if (statp->options & RES_NOALIASES)
477 file = getenv("HOSTALIASES");
478 if (file == NULL || (fp = fopen(file, "r")) == NULL)
481 buf[sizeof(buf) - 1] = '\0';
482 while (fgets(buf, sizeof(buf), fp)) {
483 for (cp1 = buf; *cp1 && !isspace(*cp1); ++cp1)
488 if (ns_samename(buf, name) == 1) {
489 while (isspace(*++cp1))
493 for (cp2 = cp1 + 1; *cp2 && !isspace(*cp2); ++cp2)
496 strncpy(dst, cp1, siz - 1);
505 libresolv_hidden_def (res_hostalias)