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[glibc.git] / resolv / res_query.c
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1 /*
2 * ++Copyright++ 1988, 1993
3 * -
4 * Copyright (c) 1988, 1993
5 * The Regents of the University of California. All rights reserved.
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. All advertising materials mentioning features or use of this software
16 * must display the following acknowledgement:
17 * This product includes software developed by the University of
18 * California, Berkeley and its contributors.
19 * 4. Neither the name of the University nor the names of its contributors
20 * may be used to endorse or promote products derived from this software
21 * without specific prior written permission.
23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33 * SUCH DAMAGE.
34 * -
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
51 * SOFTWARE.
52 * -
53 * --Copyright--
56 #if defined(LIBC_SCCS) && !defined(lint)
57 static char sccsid[] = "@(#)res_query.c 8.1 (Berkeley) 6/4/93";
58 static char rcsid[] = "$Id$";
59 #endif /* LIBC_SCCS and not lint */
61 #include <sys/types.h>
62 #include <sys/param.h>
63 #include <netinet/in.h>
64 #include <arpa/inet.h>
65 #include <arpa/nameser.h>
67 #include <stdio.h>
68 #include <netdb.h>
69 #include <resolv.h>
70 #include <ctype.h>
71 #include <errno.h>
72 #if defined(BSD) && (BSD >= 199306)
73 # include <stdlib.h>
74 # include <string.h>
75 #else
76 # include "../conf/portability.h"
77 #endif
79 #if defined(USE_OPTIONS_H)
80 # include <../conf/options.h>
81 #endif
83 #if PACKETSZ > 1024
84 #define MAXPACKET PACKETSZ
85 #else
86 #define MAXPACKET 1024
87 #endif
89 const char *hostalias __P((const char *));
93 * Formulate a normal query, send, and await answer.
94 * Returned answer is placed in supplied buffer "answer".
95 * Perform preliminary check of answer, returning success only
96 * if no error is indicated and the answer count is nonzero.
97 * Return the size of the response on success, -1 on error.
98 * Error number is left in h_errno.
100 * Caller must parse answer and determine whether it answers the question.
103 res_query(name, class, type, answer, anslen)
104 const char *name; /* domain name */
105 int class, type; /* class and type of query */
106 u_char *answer; /* buffer to put answer */
107 int anslen; /* size of answer buffer */
109 u_char buf[MAXPACKET];
110 register HEADER *hp = (HEADER *) answer;
111 int n;
113 hp->rcode = NOERROR; /* default */
115 if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
116 __set_h_errno (NETDB_INTERNAL);
117 return (-1);
119 #ifdef DEBUG
120 if (_res.options & RES_DEBUG)
121 printf(";; res_query(%s, %d, %d)\n", name, class, type);
122 #endif
124 n = res_mkquery(QUERY, name, class, type, NULL, 0, NULL,
125 buf, sizeof(buf));
126 if (n <= 0) {
127 #ifdef DEBUG
128 if (_res.options & RES_DEBUG)
129 printf(";; res_query: mkquery failed\n");
130 #endif
131 __set_h_errno (NO_RECOVERY);
132 return (n);
134 n = res_send(buf, n, answer, anslen);
135 if (n < 0) {
136 #ifdef DEBUG
137 if (_res.options & RES_DEBUG)
138 printf(";; res_query: send error\n");
139 #endif
140 __set_h_errno (TRY_AGAIN);
141 return (n);
144 if (hp->rcode != NOERROR || ntohs(hp->ancount) == 0) {
145 #ifdef DEBUG
146 if (_res.options & RES_DEBUG)
147 printf(";; rcode = %d, ancount=%d\n", hp->rcode,
148 ntohs(hp->ancount));
149 #endif
150 switch (hp->rcode) {
151 case NXDOMAIN:
152 __set_h_errno (HOST_NOT_FOUND);
153 break;
154 case SERVFAIL:
155 __set_h_errno (TRY_AGAIN);
156 break;
157 case NOERROR:
158 __set_h_errno (NO_DATA);
159 break;
160 case FORMERR:
161 case NOTIMP:
162 case REFUSED:
163 default:
164 __set_h_errno (NO_RECOVERY);
165 break;
167 return (-1);
169 return (n);
173 * Formulate a normal query, send, and retrieve answer in supplied buffer.
174 * Return the size of the response on success, -1 on error.
175 * If enabled, implement search rules until answer or unrecoverable failure
176 * is detected. Error code, if any, is left in h_errno.
179 res_search(name, class, type, answer, anslen)
180 const char *name; /* domain name */
181 int class, type; /* class and type of query */
182 u_char *answer; /* buffer to put answer */
183 int anslen; /* size of answer */
185 register const char *cp, * const *domain;
186 HEADER *hp = (HEADER *) answer;
187 u_int dots;
188 int trailing_dot, ret, saved_herrno;
189 int got_nodata = 0, got_servfail = 0, tried_as_is = 0;
191 if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
192 __set_h_errno (NETDB_INTERNAL);
193 return (-1);
195 __set_errno (0);
196 __set_h_errno (HOST_NOT_FOUND); /* default, if we never query */
197 dots = 0;
198 for (cp = name; *cp; cp++)
199 dots += (*cp == '.');
200 trailing_dot = 0;
201 if (cp > name && *--cp == '.')
202 trailing_dot++;
205 * if there aren't any dots, it could be a user-level alias
207 if (!dots && (cp = __hostalias(name)) != NULL)
208 return (res_query(cp, class, type, answer, anslen));
211 * If there are dots in the name already, let's just give it a try
212 * 'as is'. The threshold can be set with the "ndots" option.
214 saved_herrno = -1;
215 if (dots >= _res.ndots) {
216 ret = res_querydomain(name, NULL, class, type, answer, anslen);
217 if (ret > 0)
218 return (ret);
219 saved_herrno = h_errno;
220 tried_as_is++;
224 * We do at least one level of search if
225 * - there is no dot and RES_DEFNAME is set, or
226 * - there is at least one dot, there is no trailing dot,
227 * and RES_DNSRCH is set.
229 if ((!dots && (_res.options & RES_DEFNAMES)) ||
230 (dots && !trailing_dot && (_res.options & RES_DNSRCH))) {
231 int done = 0;
233 for (domain = (const char * const *)_res.dnsrch;
234 *domain && !done;
235 domain++) {
237 ret = res_querydomain(name, *domain, class, type,
238 answer, anslen);
239 if (ret > 0)
240 return (ret);
243 * If no server present, give up.
244 * If name isn't found in this domain,
245 * keep trying higher domains in the search list
246 * (if that's enabled).
247 * On a NO_DATA error, keep trying, otherwise
248 * a wildcard entry of another type could keep us
249 * from finding this entry higher in the domain.
250 * If we get some other error (negative answer or
251 * server failure), then stop searching up,
252 * but try the input name below in case it's
253 * fully-qualified.
255 if (errno == ECONNREFUSED) {
256 __set_h_errno (TRY_AGAIN);
257 return (-1);
260 switch (h_errno) {
261 case NO_DATA:
262 got_nodata++;
263 /* FALLTHROUGH */
264 case HOST_NOT_FOUND:
265 /* keep trying */
266 break;
267 case TRY_AGAIN:
268 if (hp->rcode == SERVFAIL) {
269 /* try next search element, if any */
270 got_servfail++;
271 break;
273 /* FALLTHROUGH */
274 default:
275 /* anything else implies that we're done */
276 done++;
279 /* if we got here for some reason other than DNSRCH,
280 * we only wanted one iteration of the loop, so stop.
282 if (!(_res.options & RES_DNSRCH))
283 done++;
287 /* if we have not already tried the name "as is", do that now.
288 * note that we do this regardless of how many dots were in the
289 * name or whether it ends with a dot.
291 if (!tried_as_is) {
292 ret = res_querydomain(name, NULL, class, type, answer, anslen);
293 if (ret > 0)
294 return (ret);
297 /* if we got here, we didn't satisfy the search.
298 * if we did an initial full query, return that query's h_errno
299 * (note that we wouldn't be here if that query had succeeded).
300 * else if we ever got a nodata, send that back as the reason.
301 * else send back meaningless h_errno, that being the one from
302 * the last DNSRCH we did.
304 if (saved_herrno != -1)
305 __set_h_errno (saved_herrno);
306 else if (got_nodata)
307 __set_h_errno (NO_DATA);
308 else if (got_servfail)
309 __set_h_errno (TRY_AGAIN);
310 return (-1);
314 * Perform a call on res_query on the concatenation of name and domain,
315 * removing a trailing dot from name if domain is NULL.
318 res_querydomain(name, domain, class, type, answer, anslen)
319 const char *name, *domain;
320 int class, type; /* class and type of query */
321 u_char *answer; /* buffer to put answer */
322 int anslen; /* size of answer */
324 char nbuf[MAXDNAME * 2 + 2];
325 const char *longname = nbuf;
326 int n;
328 if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
329 __set_h_errno (NETDB_INTERNAL);
330 return (-1);
332 #ifdef DEBUG
333 if (_res.options & RES_DEBUG)
334 printf(";; res_querydomain(%s, %s, %d, %d)\n",
335 name, domain?domain:"<Nil>", class, type);
336 #endif
337 if (domain == NULL) {
339 * Check for trailing '.';
340 * copy without '.' if present.
342 n = strlen(name) - 1;
343 if (n != (0 - 1) && name[n] == '.'
344 && n < (int) (sizeof(nbuf) - 1)) {
345 bcopy(name, nbuf, n);
346 nbuf[n] = '\0';
347 } else
348 longname = name;
349 } else
350 sprintf(nbuf, "%.*s.%.*s", MAXDNAME, name, MAXDNAME, domain);
352 return (res_query(longname, class, type, answer, anslen));
355 const char *
356 hostalias(name)
357 register const char *name;
359 register char *cp1, *cp2;
360 FILE *fp;
361 char *file;
362 char buf[BUFSIZ];
363 static char abuf[MAXDNAME];
365 if (_res.options & RES_NOALIASES)
366 return (NULL);
367 file = __secure_getenv("HOSTALIASES");
368 if (file == NULL || (fp = fopen(file, "r")) == NULL)
369 return (NULL);
370 setbuf(fp, NULL);
371 buf[sizeof(buf) - 1] = '\0';
372 while (fgets(buf, sizeof(buf), fp)) {
373 for (cp1 = buf; *cp1 && !isspace(*cp1); ++cp1)
375 if (!*cp1)
376 break;
377 *cp1 = '\0';
378 if (!strcasecmp(buf, name)) {
379 while (isspace(*++cp1))
381 if (!*cp1)
382 break;
383 for (cp2 = cp1 + 1; *cp2 && !isspace(*cp2); ++cp2)
385 abuf[sizeof(abuf) - 1] = *cp2 = '\0';
386 strncpy(abuf, cp1, sizeof(abuf) - 1);
387 fclose(fp);
388 return (abuf);
391 fclose(fp);
392 return (NULL);