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.
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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
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21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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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
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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
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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
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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 1.2.2.3.4.2 2004/03/16 12:34:19 marka Exp $";
74 #endif /* LIBC_SCCS and not lint */
75 #include <sys/cdefs.h>
76 __FBSDID("$FreeBSD$");
78 #include "port_before.h"
79 #include <sys/types.h>
80 #include <sys/param.h>
81 #include <netinet/in.h>
82 #include <arpa/inet.h>
83 #include <arpa/nameser.h>
92 #include "port_after.h"
94 /* Options. Leave them on. */
98 #define MAXPACKET PACKETSZ
100 #define MAXPACKET 1024
104 * Formulate a normal query, send, and await answer.
105 * Returned answer is placed in supplied buffer "answer".
106 * Perform preliminary check of answer, returning success only
107 * if no error is indicated and the answer count is nonzero.
108 * Return the size of the response on success, -1 on error.
109 * Error number is left in H_ERRNO.
111 * Caller must parse answer and determine whether it answers the question.
114 res_nquery(res_state statp,
115 const char *name, /* domain name */
116 int class, int type, /* class and type of query */
117 u_char *answer, /* buffer to put answer */
118 int anslen) /* size of answer buffer */
120 u_char buf[MAXPACKET];
121 HEADER *hp = (HEADER *) answer;
125 oflags = statp->_flags;
128 hp->rcode = NOERROR; /* default */
131 if (statp->options & RES_DEBUG)
132 printf(";; res_query(%s, %d, %d)\n", name, class, type);
135 n = res_nmkquery(statp, QUERY, name, class, type, NULL, 0, NULL,
138 if (n > 0 && (statp->_flags & RES_F_EDNS0ERR) == 0 &&
139 (statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0U)
140 n = res_nopt(statp, n, buf, sizeof(buf), anslen);
144 if (statp->options & RES_DEBUG)
145 printf(";; res_query: mkquery failed\n");
147 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. */
227 for (cp = name; *cp != '\0'; cp++)
228 dots += (*cp == '.');
230 if (cp > name && *--cp == '.')
233 /* If there aren't any dots, it could be a user-level alias. */
234 if (!dots && (cp = res_hostalias(statp, name, tmp, sizeof tmp))!= NULL)
235 return (res_nquery(statp, cp, class, type, answer, anslen));
238 * If there are enough dots in the name, let's just give it a
239 * try 'as is'. The threshold can be set with the "ndots" option.
240 * Also, query 'as is', if there is a trailing dot in the name.
243 if (dots >= statp->ndots || trailing_dot) {
244 ret = res_nquerydomain(statp, name, NULL, class, type,
246 if (ret > 0 || trailing_dot)
248 if (errno == ECONNREFUSED) {
249 RES_SET_H_ERRNO(statp, TRY_AGAIN);
252 switch (statp->res_h_errno) {
257 if (hp->rcode == SERVFAIL)
263 saved_herrno = statp->res_h_errno;
268 * We do at least one level of search if
269 * - there is no dot and RES_DEFNAME is set, or
270 * - there is at least one dot, there is no trailing dot,
271 * and RES_DNSRCH is set.
273 if ((!dots && (statp->options & RES_DEFNAMES) != 0U) ||
274 (dots && !trailing_dot && (statp->options & RES_DNSRCH) != 0U)) {
277 for (domain = (const char * const *)statp->dnsrch;
282 if (domain[0][0] == '\0' ||
283 (domain[0][0] == '.' && domain[0][1] == '\0'))
286 if (root_on_list && tried_as_is)
289 ret = res_nquerydomain(statp, name, *domain,
296 * If no server present, give up.
297 * If name isn't found in this domain,
298 * keep trying higher domains in the search list
299 * (if that's enabled).
300 * On a NO_DATA error, keep trying, otherwise
301 * a wildcard entry of another type could keep us
302 * from finding this entry higher in the domain.
303 * If we get some other error (negative answer or
304 * server failure), then stop searching up,
305 * but try the input name below in case it's
308 if (errno == ECONNREFUSED) {
309 RES_SET_H_ERRNO(statp, TRY_AGAIN);
313 switch (statp->res_h_errno) {
322 * This can occur due to a server failure
323 * (that is, all listed servers have failed),
324 * or all listed servers have timed out.
325 * ((HEADER *)answer)->rcode may not be set
326 * to SERVFAIL in the case of a timeout.
328 * Either way we must return TRY_AGAIN in
329 * order to avoid non-deterministic
331 * For example, loaded name servers or races
332 * against network startup/validation (dhcp,
333 * ppp, etc) can cause the search to timeout
334 * on one search element, e.g. 'fu.bar.com',
335 * and return a definitive failure on the
336 * next search element, e.g. 'fu.'.
339 if (hp->rcode == SERVFAIL) {
340 /* try next search element, if any */
345 /* anything else implies that we're done */
349 /* if we got here for some reason other than DNSRCH,
350 * we only wanted one iteration of the loop, so stop.
352 if ((statp->options & RES_DNSRCH) == 0U)
357 switch (statp->res_h_errno) {
362 if (hp->rcode == SERVFAIL)
370 * If the query has not already been tried as is then try it
371 * unless RES_NOTLDQUERY is set and there were no dots.
373 if ((dots || !searched || (statp->options & RES_NOTLDQUERY) == 0U) &&
374 !(tried_as_is || root_on_list)) {
375 ret = res_nquerydomain(statp, name, NULL, class, type,
381 /* if we got here, we didn't satisfy the search.
382 * if we did an initial full query, return that query's H_ERRNO
383 * (note that we wouldn't be here if that query had succeeded).
384 * else if we ever got a nodata, send that back as the reason.
385 * else send back meaningless H_ERRNO, that being the one from
386 * the last DNSRCH we did.
389 if (saved_herrno != -1)
390 RES_SET_H_ERRNO(statp, saved_herrno);
392 RES_SET_H_ERRNO(statp, NO_DATA);
393 else if (got_servfail)
394 RES_SET_H_ERRNO(statp, TRY_AGAIN);
399 * Perform a call on res_query on the concatenation of name and domain,
400 * removing a trailing dot from name if domain is NULL.
403 res_nquerydomain(res_state statp,
406 int class, int type, /* class and type of query */
407 u_char *answer, /* buffer to put answer */
408 int anslen) /* size of answer */
411 const char *longname = nbuf;
415 if (statp->options & RES_DEBUG)
416 printf(";; res_nquerydomain(%s, %s, %d, %d)\n",
417 name, domain?domain:"<Nil>", class, type);
419 if (domain == NULL) {
421 * Check for trailing '.';
422 * copy without '.' if present.
426 RES_SET_H_ERRNO(statp, NO_RECOVERY);
430 if (n >= 0 && name[n] == '.') {
431 strncpy(nbuf, name, n);
438 if (n + d + 1 >= MAXDNAME) {
439 RES_SET_H_ERRNO(statp, NO_RECOVERY);
442 sprintf(nbuf, "%s.%s", name, domain);
444 return (res_nquery(statp, longname, class, type, answer, anslen));
448 res_hostalias(const res_state statp, const char *name, char *dst, size_t siz) {
449 char *file, *cp1, *cp2;
453 if (statp->options & RES_NOALIASES)
457 file = getenv("HOSTALIASES");
458 if (file == NULL || (fp = fopen(file, "r")) == NULL)
461 buf[sizeof(buf) - 1] = '\0';
462 while (fgets(buf, sizeof(buf), fp)) {
463 for (cp1 = buf; *cp1 && !isspace((unsigned char)*cp1); ++cp1)
468 if (ns_samename(buf, name) == 1) {
469 while (isspace((unsigned char)*++cp1))
473 for (cp2 = cp1 + 1; *cp2 &&
474 !isspace((unsigned char)*cp2); ++cp2)
477 strncpy(dst, cp1, siz - 1);