1 /*
2 * Copyright (c) 1988, 1993
3 * The Regents of the University of California. All rights reserved.
4 *
5 * Portions copyright (c) 1999, 2000
6 * Intel Corporation.
7 * All rights reserved.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 *
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 *
16 * 2. Redistributions in binary form must reproduce the above copyright
17 * notice, this list of conditions and the following disclaimer in the
18 * documentation and/or other materials provided with the distribution.
19 *
20 * 3. All advertising materials mentioning features or use of this software
21 * must display the following acknowledgement:
22 *
23 * This product includes software developed by the University of
24 * California, Berkeley, Intel Corporation, and its contributors.
25 *
26 * 4. Neither the name of University, Intel Corporation, or their respective
27 * contributors may be used to endorse or promote products derived from
28 * this software without specific prior written permission.
29 *
30 * THIS SOFTWARE IS PROVIDED BY THE REGENTS, INTEL CORPORATION AND
31 * CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING,
32 * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
33 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS,
34 * INTEL CORPORATION OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
35 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
36 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
37 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
38 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
39 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
40 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
41 *
42 */
43
44 /*
45 * Portions Copyright (c) 1993 by Digital Equipment Corporation.
46 *
47 * Permission to use, copy, modify, and distribute this software for any
48 * purpose with or without fee is hereby granted, provided that the above
49 * copyright notice and this permission notice appear in all copies, and that
50 * the name of Digital Equipment Corporation not be used in advertising or
51 * publicity pertaining to distribution of the document or software without
52 * specific, written prior permission.
53 *
54 * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
55 * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
56 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL DIGITAL EQUIPMENT
57 * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
58 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
59 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
60 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
61 * SOFTWARE.
62 */
63
64 /*
65 * Portions Copyright (c) 1996 by Internet Software Consortium.
66 *
67 * Permission to use, copy, modify, and distribute this software for any
68 * purpose with or without fee is hereby granted, provided that the above
69 * copyright notice and this permission notice appear in all copies.
70 *
71 * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
72 * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
73 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
74 * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
75 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
76 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
77 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
78 * SOFTWARE.
79 */
80
81 #if defined(LIBC_SCCS) && !defined(lint)
82 static char sccsid[] = "@(#)res_query.c 8.1 (Berkeley) 6/4/93";
83 static char orig_rcsid = "From: Id: res_query.c,v 8.14 1997/06/09 17:47:05 halley Exp $";
84 static char rcsid[] = "$Id: res_query.c,v 1.1.1.1 2003/11/19 01:51:38 kyu3 Exp $";
85 #endif /* LIBC_SCCS and not lint */
86
87 #include <sys/types.h>
88 #include <sys/param.h>
89 #include <netinet/in.h>
90 #include <arpa/inet.h>
91 #include <arpa/nameser.h>
92 #include <ctype.h>
93 #include <errno.h>
94 #include <netdb.h>
95 #include <resolv.h>
96 #include <stdio.h>
97 #include <stdlib.h>
98 #include <string.h>
99
100 #include "res_config.h"
101
102 #if PACKETSZ > 1024
103 #define MAXPACKET PACKETSZ
104 #else
105 #define MAXPACKET 1024
106 #endif
107
108 /*
109 * Formulate a normal query, send, and await answer.
110 * Returned answer is placed in supplied buffer "answer".
111 * Perform preliminary check of answer, returning success only
112 * if no error is indicated and the answer count is nonzero.
113 * Return the size of the response on success, -1 on error.
114 * Error number is left in h_errno.
115 *
116 * Caller must parse answer and determine whether it answers the question.
117 */
118 int
res_query(const char * name,int class,int type,u_char * answer,int anslen)119 res_query(
120 const char *name, /* domain name */
121 int class, /* class of query */
122 int type, /* type of query */
123 u_char *answer, /* buffer to put answer */
124 int anslen /* size of answer buffer */
125 )
126 {
127 u_char buf[MAXPACKET];
128 HEADER *hp = (HEADER *) answer;
129 int n;
130
131 hp->rcode = NOERROR; /* default */
132
133 if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
134 h_errno = NETDB_INTERNAL;
135 return (-1);
136 }
137 #ifdef DEBUG
138 if (_res.options & RES_DEBUG)
139 printf(";; res_query(%s, %d, %d)\n", name, class, type);
140 #endif
141
142 n = res_mkquery(QUERY, name, class, type, NULL, 0, NULL,
143 buf, sizeof(buf));
144 if (n <= 0) {
145 #ifdef DEBUG
146 if (_res.options & RES_DEBUG)
147 printf(";; res_query: mkquery failed\n");
148 #endif
149 h_errno = NO_RECOVERY;
150 return (n);
151 }
152 n = res_send(buf, n, answer, anslen);
153 if (n < 0) {
154 #ifdef DEBUG
155 if (_res.options & RES_DEBUG)
156 printf(";; res_query: send error\n");
157 #endif
158 h_errno = TRY_AGAIN;
159 return (n);
160 }
161
162 if (hp->rcode != NOERROR || ntohs(hp->ancount) == 0) {
163 #ifdef DEBUG
164 if (_res.options & RES_DEBUG)
165 printf(";; rcode = %d, ancount=%d\n", hp->rcode,
166 ntohs(hp->ancount));
167 #endif
168 switch (hp->rcode) {
169 case NXDOMAIN:
170 h_errno = HOST_NOT_FOUND;
171 break;
172 case SERVFAIL:
173 h_errno = TRY_AGAIN;
174 break;
175 case NOERROR:
176 h_errno = NO_DATA;
177 break;
178 case FORMERR:
179 case NOTIMP:
180 case REFUSED:
181 default:
182 h_errno = NO_RECOVERY;
183 break;
184 }
185 return (-1);
186 }
187 return (n);
188 }
189
190 /*
191 * Formulate a normal query, send, and retrieve answer in supplied buffer.
192 * Return the size of the response on success, -1 on error.
193 * If enabled, implement search rules until answer or unrecoverable failure
194 * is detected. Error code, if any, is left in h_errno.
195 */
196 int
res_search(const char * name,int class,int type,u_char * answer,int anslen)197 res_search(
198 const char *name, /* domain name */
199 int class, /* class of query */
200 int type, /* type of query */
201 u_char *answer, /* buffer to put answer */
202 int anslen /* size of answer */
203 )
204 {
205 const char *cp, * const *domain;
206 HEADER *hp = (HEADER *) answer;
207 u_int dots;
208 int trailing_dot, ret, saved_herrno;
209 int got_nodata = 0, got_servfail = 0, tried_as_is = 0;
210
211 if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
212 h_errno = NETDB_INTERNAL;
213 return (-1);
214 }
215 errno = 0;
216 h_errno = HOST_NOT_FOUND; /* default, if we never query */
217 dots = 0;
218 for (cp = name; *cp; cp++)
219 dots += (*cp == '.');
220 trailing_dot = 0;
221 if (cp > name && *--cp == '.')
222 trailing_dot++;
223
224 /* If there aren't any dots, it could be a user-level alias */
225 if (!dots && (cp = hostalias(name)) != NULL)
226 return (res_query(cp, class, type, answer, anslen));
227
228 /*
229 * If there are dots in the name already, let's just give it a try
230 * 'as is'. The threshold can be set with the "ndots" option.
231 */
232 saved_herrno = -1;
233 if (dots >= _res.ndots) {
234 ret = res_querydomain(name, NULL, class, type, answer, anslen);
235 if (ret > 0)
236 return (ret);
237 saved_herrno = h_errno;
238 tried_as_is++;
239 }
240
241 /*
242 * We do at least one level of search if
243 * - there is no dot and RES_DEFNAME is set, or
244 * - there is at least one dot, there is no trailing dot,
245 * and RES_DNSRCH is set.
246 */
247 if ((!dots && (_res.options & RES_DEFNAMES)) ||
248 (dots && !trailing_dot && (_res.options & RES_DNSRCH))) {
249 int done = 0;
250
251 for (domain = (const char * const *)_res.dnsrch;
252 *domain && !done;
253 domain++) {
254
255 ret = res_querydomain(name, *domain, class, type,
256 answer, anslen);
257 if (ret > 0)
258 return (ret);
259
260 /*
261 * If no server present, give up.
262 * If name isn't found in this domain,
263 * keep trying higher domains in the search list
264 * (if that's enabled).
265 * On a NO_DATA error, keep trying, otherwise
266 * a wildcard entry of another type could keep us
267 * from finding this entry higher in the domain.
268 * If we get some other error (negative answer or
269 * server failure), then stop searching up,
270 * but try the input name below in case it's
271 * fully-qualified.
272 */
273 if (errno == ECONNREFUSED) {
274 h_errno = TRY_AGAIN;
275 return (-1);
276 }
277
278 switch (h_errno) {
279 case NO_DATA:
280 got_nodata++;
281 /* FALLTHROUGH */
282 case HOST_NOT_FOUND:
283 /* keep trying */
284 break;
285 case TRY_AGAIN:
286 if (hp->rcode == SERVFAIL) {
287 /* try next search element, if any */
288 got_servfail++;
289 break;
290 }
291 /* FALLTHROUGH */
292 default:
293 /* anything else implies that we're done */
294 done++;
295 }
296
297 /* if we got here for some reason other than DNSRCH,
298 * we only wanted one iteration of the loop, so stop.
299 */
300 if (!(_res.options & RES_DNSRCH))
301 done++;
302 }
303 }
304
305 /*
306 * If we have not already tried the name "as is", do that now.
307 * note that we do this regardless of how many dots were in the
308 * name or whether it ends with a dot unless NOTLDQUERY is set.
309 */
310 if (!tried_as_is && (dots || !(_res.options & RES_NOTLDQUERY))) {
311 ret = res_querydomain(name, NULL, class, type, answer, anslen);
312 if (ret > 0)
313 return (ret);
314 }
315
316 /* if we got here, we didn't satisfy the search.
317 * if we did an initial full query, return that query's h_errno
318 * (note that we wouldn't be here if that query had succeeded).
319 * else if we ever got a nodata, send that back as the reason.
320 * else send back meaningless h_errno, that being the one from
321 * the last DNSRCH we did.
322 */
323 if (saved_herrno != -1)
324 h_errno = saved_herrno;
325 else if (got_nodata)
326 h_errno = NO_DATA;
327 else if (got_servfail)
328 h_errno = TRY_AGAIN;
329 return (-1);
330 }
331
332 /*
333 * Perform a call on res_query on the concatenation of name and domain,
334 * removing a trailing dot from name if domain is NULL.
335 */
336 int
res_querydomain(const char * name,const char * domain,int class,int type,u_char * answer,int anslen)337 res_querydomain(
338 const char *name,
339 const char *domain,
340 int class, /* class of query */
341 int type, /* type of query */
342 u_char *answer, /* buffer to put answer */
343 int anslen /* size of answer */
344 )
345 {
346 char nbuf[MAXDNAME];
347 const char *longname = nbuf;
348 int n, d;
349
350 if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
351 h_errno = NETDB_INTERNAL;
352 return (-1);
353 }
354 #ifdef DEBUG
355 if (_res.options & RES_DEBUG)
356 printf(";; res_querydomain(%s, %s, %d, %d)\n",
357 name, domain?domain:"<Nil>", class, type);
358 #endif
359 if (domain == NULL) {
360 /*
361 * Check for trailing '.';
362 * copy without '.' if present.
363 */
364 n = (int)strlen(name);
365 if (n >= MAXDNAME) {
366 h_errno = NO_RECOVERY;
367 return (-1);
368 }
369 n--;
370 if (n >= 0 && name[n] == '.') {
371 strncpy(nbuf, name, n);
372 nbuf[n] = '\0';
373 } else
374 longname = name;
375 } else {
376 n = (int)strlen(name);
377 d = (int)strlen(domain);
378 if (n + d + 1 >= MAXDNAME) {
379 h_errno = NO_RECOVERY;
380 return (-1);
381 }
382 sprintf(nbuf, "%s.%s", name, domain);
383 }
384 return (res_query(longname, class, type, answer, anslen));
385 }
386
387 const char *
hostalias(const char * name)388 hostalias(
389 const char *name
390 )
391 {
392 register char *cp1, *cp2;
393 FILE *fp;
394 char *file;
395 char buf[BUFSIZ];
396 static char abuf[MAXDNAME];
397
398 if (_res.options & RES_NOALIASES)
399 return (NULL);
400 #ifdef _ORG_FREEBSD_
401 if (issetugid())
402 return (NULL);
403 #endif
404 file = getenv("HOSTALIASES");
405 if (file == NULL || (fp = fopen(file, "r")) == NULL)
406 return (NULL);
407 setbuf(fp, NULL);
408 buf[sizeof(buf) - 1] = '\0';
409 while (fgets(buf, sizeof(buf), fp)) {
410 for (cp1 = buf; *cp1 && !isspace(*cp1); ++cp1)
411 ;
412 if (!*cp1)
413 break;
414 *cp1 = '\0';
415 if (!strcasecmp(buf, name)) {
416 while (isspace(*++cp1))
417 ;
418 if (!*cp1)
419 break;
420 for (cp2 = cp1 + 1; *cp2 && !isspace(*cp2); ++cp2)
421 ;
422 abuf[sizeof(abuf) - 1] = *cp2 = '\0';
423 strncpy(abuf, cp1, sizeof(abuf) - 1);
424 fclose(fp);
425 return (abuf);
426 }
427 }
428 fclose(fp);
429 return (NULL);
430 }
431