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
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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
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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
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36 * the name of Digital Equipment Corporation not be used in advertising or
37 * publicity pertaining to distribution of the document or software without
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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
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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 */
72 #include <sys/types.h>
73 #include <sys/param.h>
74 #include <netinet/in.h>
75 #include <arpa/inet.h>
76 #include <arpa/nameser.h>
85 /* Options. Leave them on. */
89 #define MAXPACKET PACKETSZ
91 #define MAXPACKET 65536
94 #define QUERYSIZE (HFIXEDSZ + QFIXEDSZ + MAXCDNAME + 1)
97 __libc_res_nquerydomain(res_state statp, const char *name, const char *domain,
98 int class, int type, u_char *answer, int anslen,
102 * Formulate a normal query, send, and await answer.
103 * Returned answer is placed in supplied buffer "answer".
104 * Perform preliminary check of answer, returning success only
105 * if no error is indicated and the answer count is nonzero.
106 * Return the size of the response on success, -1 on error.
107 * Error number is left in H_ERRNO.
109 * Caller must parse answer and determine whether it answers the question.
112 __libc_res_nquery(res_state statp,
113 const char *name, /* domain name */
114 int class, int type, /* class and type of query */
115 u_char *answer, /* buffer to put answer */
116 int anslen, /* size of answer buffer */
117 u_char **answerp) /* if buffer needs to be enlarged */
120 HEADER *hp = (HEADER *) answer;
121 int n, use_malloc = 0;
123 hp->rcode = NOERROR; /* default */
125 buf = alloca (QUERYSIZE);
128 if (statp->options & RES_DEBUG)
129 printf(";; res_query(%s, %d, %d)\n", name, class, type);
132 n = res_nmkquery(statp, QUERY, name, class, type, NULL, 0, NULL,
134 if (__builtin_expect (n <= 0, 0)) {
135 /* Retry just in case res_nmkquery failed because of too
136 short buffer. Shouldn't happen. */
137 buf = malloc (MAXPACKET);
140 n = res_nmkquery(statp, QUERY, name, class, type, NULL,
141 0, NULL, buf, MAXPACKET);
144 if (__builtin_expect (n <= 0, 0)) {
146 if (statp->options & RES_DEBUG)
147 printf(";; res_query: mkquery failed\n");
149 RES_SET_H_ERRNO(statp, NO_RECOVERY);
154 n = __libc_res_nsend(statp, buf, n, answer, anslen, answerp);
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 = %d, ancount=%d\n", hp->rcode,
174 RES_SET_H_ERRNO(statp, HOST_NOT_FOUND);
177 RES_SET_H_ERRNO(statp, TRY_AGAIN);
180 RES_SET_H_ERRNO(statp, NO_DATA);
186 RES_SET_H_ERRNO(statp, NO_RECOVERY);
195 res_nquery(res_state statp,
196 const char *name, /* domain name */
197 int class, int type, /* class and type of query */
198 u_char *answer, /* buffer to put answer */
199 int anslen) /* size of answer buffer */
201 return __libc_res_nquery(statp, name, class, type, answer, anslen,
206 * Formulate a normal query, send, and retrieve answer in supplied buffer.
207 * Return the size of the response on success, -1 on error.
208 * If enabled, implement search rules until answer or unrecoverable failure
209 * is detected. Error code, if any, is left in H_ERRNO.
212 __libc_res_nsearch(res_state statp,
213 const char *name, /* domain name */
214 int class, int type, /* class and type of query */
215 u_char *answer, /* buffer to put answer */
216 int anslen, /* size of answer */
219 const char *cp, * const *domain;
220 HEADER *hp = (HEADER *) answer;
221 char tmp[NS_MAXDNAME];
223 int trailing_dot, ret, saved_herrno;
224 int got_nodata = 0, got_servfail = 0, root_on_list = 0;
228 RES_SET_H_ERRNO(statp, HOST_NOT_FOUND); /* True if we never query. */
231 for (cp = name; *cp != '\0'; cp++)
232 dots += (*cp == '.');
234 if (cp > name && *--cp == '.')
237 /* If there aren't any dots, it could be a user-level alias. */
238 if (!dots && (cp = res_hostalias(statp, name, tmp, sizeof tmp))!= NULL)
239 return (__libc_res_nquery(statp, cp, class, type, answer,
242 printf("dots=%d, statp->ndots=%d, trailing_dot=%d, name=%s\n",
243 (int)dots,(int)statp->ndots,(int)trailing_dot,name);
246 * If there are enough dots in the name, let's just give it a
247 * try 'as is'. The threshold can be set with the "ndots" option.
248 * Also, query 'as is', if there is a trailing dot in the name.
251 if (dots >= statp->ndots || trailing_dot) {
252 ret = __libc_res_nquerydomain(statp, name, NULL, class, type,
253 answer, anslen, answerp);
254 if (ret > 0 || trailing_dot)
256 saved_herrno = h_errno;
258 if (answerp && *answerp != answer) {
265 * We do at least one level of search if
266 * - there is no dot and RES_DEFNAME is set, or
267 * - there is at least one dot, there is no trailing dot,
268 * and RES_DNSRCH is set.
270 if ((!dots && (statp->options & RES_DEFNAMES) != 0) ||
271 (dots && !trailing_dot && (statp->options & RES_DNSRCH) != 0)) {
274 for (domain = (const char * const *)statp->dnsrch;
278 if (domain[0][0] == '\0' ||
279 (domain[0][0] == '.' && domain[0][1] == '\0'))
282 ret = __libc_res_nquerydomain(statp, name, *domain,
284 answer, anslen, answerp);
288 if (answerp && *answerp != answer) {
294 * If no server present, give up.
295 * If name isn't found in this domain,
296 * keep trying higher domains in the search list
297 * (if that's enabled).
298 * On a NO_DATA error, keep trying, otherwise
299 * a wildcard entry of another type could keep us
300 * from finding this entry higher in the domain.
301 * If we get some other error (negative answer or
302 * server failure), then stop searching up,
303 * but try the input name below in case it's
306 if (errno == ECONNREFUSED) {
307 RES_SET_H_ERRNO(statp, TRY_AGAIN);
311 switch (statp->res_h_errno) {
319 if (hp->rcode == SERVFAIL) {
320 /* try next search element, if any */
326 /* anything else implies that we're done */
330 /* if we got here for some reason other than DNSRCH,
331 * we only wanted one iteration of the loop, so stop.
333 if ((statp->options & RES_DNSRCH) == 0)
339 * If the name has any dots at all, and no earlier 'as-is' query
340 * for the name, and "." is not on the search list, then try an as-is
343 if (dots && !(tried_as_is || root_on_list)) {
344 ret = __libc_res_nquerydomain(statp, name, NULL, class, type,
345 answer, anslen, answerp);
350 /* if we got here, we didn't satisfy the search.
351 * if we did an initial full query, return that query's H_ERRNO
352 * (note that we wouldn't be here if that query had succeeded).
353 * else if we ever got a nodata, send that back as the reason.
354 * else send back meaningless H_ERRNO, that being the one from
355 * the last DNSRCH we did.
357 if (saved_herrno != -1)
358 RES_SET_H_ERRNO(statp, saved_herrno);
360 RES_SET_H_ERRNO(statp, NO_DATA);
361 else if (got_servfail)
362 RES_SET_H_ERRNO(statp, TRY_AGAIN);
367 res_nsearch(res_state statp,
368 const char *name, /* domain name */
369 int class, int type, /* class and type of query */
370 u_char *answer, /* buffer to put answer */
371 int anslen) /* size of answer */
373 return __libc_res_nsearch(statp, name, class, type, answer,
378 * Perform a call on res_query on the concatenation of name and domain,
379 * removing a trailing dot from name if domain is NULL.
382 __libc_res_nquerydomain(res_state statp,
385 int class, int type, /* class and type of query */
386 u_char *answer, /* buffer to put answer */
387 int anslen, /* size of answer */
391 const char *longname = nbuf;
394 write(2,"<<aaaa\n",7);
397 if (statp->options & RES_DEBUG)
398 printf(";; res_nquerydomain(%s, %s, %d, %d)\n",
399 name, domain?domain:"<Nil>", class, type);
401 if (domain == NULL) {
403 * Check for trailing '.';
404 * copy without '.' if present.
408 RES_SET_H_ERRNO(statp, NO_RECOVERY);
412 if (n >= 0 && name[n] == '.') {
413 strncpy(nbuf, name, n);
420 if (n + d + 1 >= MAXDNAME) {
421 RES_SET_H_ERRNO(statp, NO_RECOVERY);
424 sprintf(nbuf, "%s.%s", name, domain);
426 int r = (__libc_res_nquery(statp, longname, class, type, answer,
428 write(2,">>aaaa\n",7);
434 res_nquerydomain(res_state statp,
437 int class, int type, /* class and type of query */
438 u_char *answer, /* buffer to put answer */
439 int anslen) /* size of answer */
441 return __libc_res_nquerydomain(statp, name, domain, class, type,
442 answer, anslen, NULL);
446 res_hostalias(const res_state statp, const char *name, char *dst, size_t siz) {
447 char *file, *cp1, *cp2;
451 if (statp->options & RES_NOALIASES)
453 file = getenv("HOSTALIASES");
454 if (file == NULL || (fp = fopen(file, "r")) == NULL)
457 buf[sizeof(buf) - 1] = '\0';
458 while (fgets(buf, sizeof(buf), fp)) {
459 for (cp1 = buf; *cp1 && !isspace(*cp1); ++cp1)
464 if (ns_samename(buf, name) == 1) {
465 while (isspace(*++cp1))
469 for (cp2 = cp1 + 1; *cp2 && !isspace(*cp2); ++cp2)
472 strncpy(dst, cp1, siz - 1);