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
19 * without specific prior written permission.
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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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
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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 1.7.18.1 2005/04/27 05:01:11 sra 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;
122 oflags = statp->_flags;
125 hp->rcode = NOERROR; /*%< default */
127 if (statp->options & RES_DEBUG)
128 printf(";; res_query(%s, %d, %d)\n", name, class, type);
131 n = res_nmkquery(statp, QUERY, name, class, type, NULL, 0, NULL,
134 if (n > 0 && (statp->_flags & RES_F_EDNS0ERR) == 0 &&
135 (statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0U)
136 n = res_nopt(statp, n, buf, sizeof(buf), anslen);
140 if (statp->options & RES_DEBUG)
141 printf(";; res_query: mkquery failed\n");
143 RES_SET_H_ERRNO(statp, NO_RECOVERY);
146 n = res_nsend(statp, buf, n, answer, anslen);
149 /* if the query choked with EDNS0, retry without EDNS0 */
150 if ((statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0U &&
151 ((oflags ^ statp->_flags) & RES_F_EDNS0ERR) != 0) {
152 statp->_flags |= RES_F_EDNS0ERR;
153 if (statp->options & RES_DEBUG)
154 printf(";; res_nquery: retry without EDNS0\n");
159 if (statp->options & RES_DEBUG)
160 printf(";; res_query: send error\n");
162 RES_SET_H_ERRNO(statp, TRY_AGAIN);
166 if (hp->rcode != NOERROR || ntohs(hp->ancount) == 0) {
168 if (statp->options & RES_DEBUG)
169 printf(";; rcode = (%s), counts = an:%d ns:%d ar:%d\n",
177 RES_SET_H_ERRNO(statp, HOST_NOT_FOUND);
180 RES_SET_H_ERRNO(statp, TRY_AGAIN);
183 RES_SET_H_ERRNO(statp, NO_DATA);
189 RES_SET_H_ERRNO(statp, NO_RECOVERY);
198 * Formulate a normal query, send, and retrieve answer in supplied buffer.
199 * Return the size of the response on success, -1 on error.
200 * If enabled, implement search rules until answer or unrecoverable failure
201 * is detected. Error code, if any, is left in H_ERRNO.
204 res_nsearch(res_state statp,
205 const char *name, /*%< domain name */
206 int class, int type, /*%< class and type of query */
207 u_char *answer, /*%< buffer to put answer */
208 int anslen) /*%< size of answer */
210 const char *cp, * const *domain;
211 HEADER *hp = (HEADER *) answer;
212 char tmp[NS_MAXDNAME];
214 int trailing_dot, ret, saved_herrno;
215 int got_nodata = 0, got_servfail = 0, root_on_list = 0;
220 RES_SET_H_ERRNO(statp, HOST_NOT_FOUND); /*%< True if we never query. */
222 for (cp = name; *cp != '\0'; cp++)
223 dots += (*cp == '.');
225 if (cp > name && *--cp == '.')
228 /* If there aren't any dots, it could be a user-level alias. */
229 if (!dots && (cp = res_hostalias(statp, name, tmp, sizeof tmp))!= NULL)
230 return (res_nquery(statp, cp, class, type, answer, anslen));
233 * If there are enough dots in the name, let's just give it a
234 * try 'as is'. The threshold can be set with the "ndots" option.
235 * Also, query 'as is', if there is a trailing dot in the name.
238 if (dots >= statp->ndots || trailing_dot) {
239 ret = res_nquerydomain(statp, name, NULL, class, type,
241 if (ret > 0 || trailing_dot)
243 saved_herrno = statp->res_h_errno;
248 * We do at least one level of search if
249 * - there is no dot and RES_DEFNAME is set, or
250 * - there is at least one dot, there is no trailing dot,
251 * and RES_DNSRCH is set.
253 if ((!dots && (statp->options & RES_DEFNAMES) != 0U) ||
254 (dots && !trailing_dot && (statp->options & RES_DNSRCH) != 0U)) {
257 for (domain = (const char * const *)statp->dnsrch;
262 if (domain[0][0] == '\0' ||
263 (domain[0][0] == '.' && domain[0][1] == '\0'))
266 ret = res_nquerydomain(statp, name, *domain,
273 * If no server present, give up.
274 * If name isn't found in this domain,
275 * keep trying higher domains in the search list
276 * (if that's enabled).
277 * On a NO_DATA error, keep trying, otherwise
278 * a wildcard entry of another type could keep us
279 * from finding this entry higher in the domain.
280 * If we get some other error (negative answer or
281 * server failure), then stop searching up,
282 * but try the input name below in case it's
285 if (errno == ECONNREFUSED) {
286 RES_SET_H_ERRNO(statp, TRY_AGAIN);
290 switch (statp->res_h_errno) {
298 if (hp->rcode == SERVFAIL) {
299 /* try next search element, if any */
305 /* anything else implies that we're done */
309 /* if we got here for some reason other than DNSRCH,
310 * we only wanted one iteration of the loop, so stop.
312 if ((statp->options & RES_DNSRCH) == 0U)
318 * If the query has not already been tried as is then try it
319 * unless RES_NOTLDQUERY is set and there were no dots.
321 if ((dots || !searched || (statp->options & RES_NOTLDQUERY) == 0U) &&
322 !(tried_as_is || root_on_list)) {
323 ret = res_nquerydomain(statp, name, NULL, class, type,
329 /* if we got here, we didn't satisfy the search.
330 * if we did an initial full query, return that query's H_ERRNO
331 * (note that we wouldn't be here if that query had succeeded).
332 * else if we ever got a nodata, send that back as the reason.
333 * else send back meaningless H_ERRNO, that being the one from
334 * the last DNSRCH we did.
336 if (saved_herrno != -1)
337 RES_SET_H_ERRNO(statp, saved_herrno);
339 RES_SET_H_ERRNO(statp, NO_DATA);
340 else if (got_servfail)
341 RES_SET_H_ERRNO(statp, TRY_AGAIN);
346 * Perform a call on res_query on the concatenation of name and domain,
347 * removing a trailing dot from name if domain is NULL.
350 res_nquerydomain(res_state statp,
353 int class, int type, /*%< class and type of query */
354 u_char *answer, /*%< buffer to put answer */
355 int anslen) /*%< size of answer */
358 const char *longname = nbuf;
362 if (statp->options & RES_DEBUG)
363 printf(";; res_nquerydomain(%s, %s, %d, %d)\n",
364 name, domain?domain:"<Nil>", class, type);
366 if (domain == NULL) {
368 * Check for trailing '.';
369 * copy without '.' if present.
373 RES_SET_H_ERRNO(statp, NO_RECOVERY);
377 if (n >= 0 && name[n] == '.') {
378 strncpy(nbuf, name, n);
385 if (n + d + 1 >= MAXDNAME) {
386 RES_SET_H_ERRNO(statp, NO_RECOVERY);
389 sprintf(nbuf, "%s.%s", name, domain);
391 return (res_nquery(statp, longname, class, type, answer, anslen));
395 res_hostalias(const res_state statp, const char *name, char *dst, size_t siz) {
396 char *file, *cp1, *cp2;
400 if (statp->options & RES_NOALIASES)
402 file = getenv("HOSTALIASES");
403 if (file == NULL || (fp = fopen(file, "r")) == NULL)
406 buf[sizeof(buf) - 1] = '\0';
407 while (fgets(buf, sizeof(buf), fp)) {
408 for (cp1 = buf; *cp1 && !isspace((unsigned char)*cp1); ++cp1)
413 if (ns_samename(buf, name) == 1) {
414 while (isspace((unsigned char)*++cp1))
418 for (cp2 = cp1 + 1; *cp2 &&
419 !isspace((unsigned char)*cp2); ++cp2)
422 strncpy(dst, cp1, siz - 1);