1 /*
2 * Portions Copyright (C) 2004, 2005, 2008 Internet Systems Consortium, Inc. ("ISC")
3 * Portions Copyright (C) 1996-2001, 2003 Internet Software Consortium.
4 *
5 * Permission to use, copy, modify, and/or distribute this software for any
6 * purpose with or without fee is hereby granted, provided that the above
7 * copyright notice and this permission notice appear in all copies.
8 *
9 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
10 * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
11 * AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
12 * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
13 * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
14 * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
15 * PERFORMANCE OF THIS SOFTWARE.
16 */
17
18 /*
19 * Copyright (c) 1988, 1993
20 * The Regents of the University of California. All rights reserved.
21 *
22 * Redistribution and use in source and binary forms, with or without
23 * modification, are permitted provided that the following conditions
24 * are met:
25 * 1. Redistributions of source code must retain the above copyright
26 * notice, this list of conditions and the following disclaimer.
27 * 2. Redistributions in binary form must reproduce the above copyright
28 * notice, this list of conditions and the following disclaimer in the
29 * documentation and/or other materials provided with the distribution.
30 * 3. All advertising materials mentioning features or use of this software
31 * must display the following acknowledgement:
32 * This product includes software developed by the University of
33 * California, Berkeley and its contributors.
34 * 4. Neither the name of the University nor the names of its contributors
35 * may be used to endorse or promote products derived from this software
36 * without specific prior written permission.
37 *
38 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
39 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
40 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
41 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
42 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
43 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
44 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
45 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
46 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
47 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
48 * SUCH DAMAGE.
49 */
50
51 /*
52 * Portions Copyright (c) 1993 by Digital Equipment Corporation.
53 *
54 * Permission to use, copy, modify, and distribute this software for any
55 * purpose with or without fee is hereby granted, provided that the above
56 * copyright notice and this permission notice appear in all copies, and that
57 * the name of Digital Equipment Corporation not be used in advertising or
58 * publicity pertaining to distribution of the document or software without
59 * specific, written prior permission.
60 *
61 * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
62 * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
63 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL DIGITAL EQUIPMENT
64 * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
65 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
66 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
67 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
68 * SOFTWARE.
69 */
70
71 #include "port_before.h"
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>
77 #include <ctype.h>
78 #include <errno.h>
79 #include <netdb.h>
80 #include <resolv.h>
81 #include <stdio.h>
82 #include <stdlib.h>
83 #include <string.h>
84 #include "port_after.h"
85
86 /* Options. Leave them on. */
87 #define DEBUG
88
89 #if PACKETSZ > 1024
90 #define MAXPACKET PACKETSZ
91 #else
92 #define MAXPACKET 1024
93 #endif
94
95 /*%
96 * Formulate a normal query, send, and await answer.
97 * Returned answer is placed in supplied buffer "answer".
98 * Perform preliminary check of answer, returning success only
99 * if no error is indicated and the answer count is nonzero.
100 * Return the size of the response on success, -1 on error.
101 * Error number is left in H_ERRNO.
102 *
103 * Caller must parse answer and determine whether it answers the question.
104 */
105 int
res_nquery(res_state statp,const char * name,int class,int type,u_char * answer,int anslen)106 res_nquery(res_state statp,
107 const char *name, /*%< domain name */
108 int class, int type, /*%< class and type of query */
109 u_char *answer, /*%< buffer to put answer */
110 int anslen) /*%< size of answer buffer */
111 {
112 u_char buf[MAXPACKET];
113 HEADER *hp = (HEADER *) answer;
114 u_int oflags;
115 u_char *rdata;
116 int n;
117
118 oflags = statp->_flags;
119
120 again:
121 hp->rcode = NOERROR; /*%< default */
122 #ifdef DEBUG
123 if (statp->options & RES_DEBUG)
124 printf(";; res_query(%s, %d, %d)\n", name, class, type);
125 #endif
126
127 n = res_nmkquery(statp, QUERY, name, class, type, NULL, 0, NULL,
128 buf, sizeof(buf));
129 #ifdef RES_USE_EDNS0
130 if (n > 0 && (statp->_flags & RES_F_EDNS0ERR) == 0 &&
131 (statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC|RES_NSID))) {
132 n = res_nopt(statp, n, buf, sizeof(buf), anslen);
133 rdata = &buf[n];
134 if (n > 0 && (statp->options & RES_NSID) != 0U) {
135 n = res_nopt_rdata(statp, n, buf, sizeof(buf), rdata,
136 NS_OPT_NSID, 0, NULL);
137 }
138 }
139 #endif
140 if (n <= 0) {
141 #ifdef DEBUG
142 if (statp->options & RES_DEBUG)
143 printf(";; res_query: mkquery failed\n");
144 #endif
145 RES_SET_H_ERRNO(statp, NO_RECOVERY);
146 return (n);
147 }
148
149 n = res_nsend(statp, buf, n, answer, anslen);
150 if (n < 0) {
151 #ifdef RES_USE_EDNS0
152 /* if the query choked with EDNS0, retry without EDNS0 */
153 if ((statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0U &&
154 ((oflags ^ statp->_flags) & RES_F_EDNS0ERR) != 0) {
155 statp->_flags |= RES_F_EDNS0ERR;
156 if (statp->options & RES_DEBUG)
157 printf(";; res_nquery: retry without EDNS0\n");
158 goto again;
159 }
160 #endif
161 #ifdef DEBUG
162 if (statp->options & RES_DEBUG)
163 printf(";; res_query: send error\n");
164 #endif
165 RES_SET_H_ERRNO(statp, TRY_AGAIN);
166 return (n);
167 }
168
169 if (hp->rcode != NOERROR || ntohs(hp->ancount) == 0) {
170 #ifdef DEBUG
171 if (statp->options & RES_DEBUG)
172 printf(";; rcode = (%s), counts = an:%d ns:%d ar:%d\n",
173 p_rcode(hp->rcode),
174 ntohs(hp->ancount),
175 ntohs(hp->nscount),
176 ntohs(hp->arcount));
177 #endif
178 switch (hp->rcode) {
179 case NXDOMAIN:
180 RES_SET_H_ERRNO(statp, HOST_NOT_FOUND);
181 break;
182 case SERVFAIL:
183 RES_SET_H_ERRNO(statp, TRY_AGAIN);
184 break;
185 case NOERROR:
186 RES_SET_H_ERRNO(statp, NO_DATA);
187 break;
188 case FORMERR:
189 case NOTIMP:
190 case REFUSED:
191 default:
192 RES_SET_H_ERRNO(statp, NO_RECOVERY);
193 break;
194 }
195 return (-1);
196 }
197 return (n);
198 }
199
200 /*%
201 * Formulate a normal query, send, and retrieve answer in supplied buffer.
202 * Return the size of the response on success, -1 on error.
203 * If enabled, implement search rules until answer or unrecoverable failure
204 * is detected. Error code, if any, is left in H_ERRNO.
205 */
206 int
res_nsearch(res_state statp,const char * name,int class,int type,u_char * answer,int anslen)207 res_nsearch(res_state statp,
208 const char *name, /*%< domain name */
209 int class, int type, /*%< class and type of query */
210 u_char *answer, /*%< buffer to put answer */
211 int anslen) /*%< size of answer */
212 {
213 const char *cp, * const *domain;
214 HEADER *hp = (HEADER *) answer;
215 char tmp[NS_MAXDNAME];
216 u_int dots;
217 int trailing_dot, ret, saved_herrno;
218 int got_nodata = 0, got_servfail = 0, root_on_list = 0;
219 int tried_as_is = 0;
220 int searched = 0;
221
222 errno = 0;
223 RES_SET_H_ERRNO(statp, HOST_NOT_FOUND); /*%< True if we never query. */
224 dots = 0;
225 for (cp = name; *cp != '\0'; cp++)
226 dots += (*cp == '.');
227 trailing_dot = 0;
228 if (cp > name && *--cp == '.')
229 trailing_dot++;
230
231 /* If there aren't any dots, it could be a user-level alias. */
232 if (!dots && (cp = res_hostalias(statp, name, tmp, sizeof tmp))!= NULL)
233 return (res_nquery(statp, cp, class, type, answer, anslen));
234
235 /*
236 * If there are enough dots in the name, let's just give it a
237 * try 'as is'. The threshold can be set with the "ndots" option.
238 * Also, query 'as is', if there is a trailing dot in the name.
239 */
240 saved_herrno = -1;
241 if (dots >= statp->ndots || trailing_dot) {
242 ret = res_nquerydomain(statp, name, NULL, class, type,
243 answer, anslen);
244 if (ret > 0 || trailing_dot)
245 return (ret);
246 saved_herrno = statp->res_h_errno;
247 tried_as_is++;
248 }
249
250 /*
251 * We do at least one level of search if
252 * - there is no dot and RES_DEFNAME is set, or
253 * - there is at least one dot, there is no trailing dot,
254 * and RES_DNSRCH is set.
255 */
256 if ((!dots && (statp->options & RES_DEFNAMES) != 0U) ||
257 (dots && !trailing_dot && (statp->options & RES_DNSRCH) != 0U)) {
258 int done = 0;
259
260 for (domain = (const char * const *)statp->dnsrch;
261 *domain && !done;
262 domain++) {
263 searched = 1;
264
265 if (domain[0][0] == '\0' ||
266 (domain[0][0] == '.' && domain[0][1] == '\0'))
267 root_on_list++;
268
269 ret = res_nquerydomain(statp, name, *domain,
270 class, type,
271 answer, anslen);
272 if (ret > 0)
273 return (ret);
274
275 /*
276 * If no server present, give up.
277 * If name isn't found in this domain,
278 * keep trying higher domains in the search list
279 * (if that's enabled).
280 * On a NO_DATA error, keep trying, otherwise
281 * a wildcard entry of another type could keep us
282 * from finding this entry higher in the domain.
283 * If we get some other error (negative answer or
284 * server failure), then stop searching up,
285 * but try the input name below in case it's
286 * fully-qualified.
287 */
288 if (errno == ECONNREFUSED) {
289 RES_SET_H_ERRNO(statp, TRY_AGAIN);
290 return (-1);
291 }
292
293 switch (statp->res_h_errno) {
294 case NO_DATA:
295 got_nodata++;
296 /* FALLTHROUGH */
297 case HOST_NOT_FOUND:
298 /* keep trying */
299 break;
300 case TRY_AGAIN:
301 if (hp->rcode == SERVFAIL) {
302 /* try next search element, if any */
303 got_servfail++;
304 break;
305 }
306 /* FALLTHROUGH */
307 default:
308 /* anything else implies that we're done */
309 done++;
310 }
311
312 /* if we got here for some reason other than DNSRCH,
313 * we only wanted one iteration of the loop, so stop.
314 */
315 if ((statp->options & RES_DNSRCH) == 0U)
316 done++;
317 }
318 }
319
320 /*
321 * If the query has not already been tried as is then try it
322 * unless RES_NOTLDQUERY is set and there were no dots.
323 */
324 if ((dots || !searched || (statp->options & RES_NOTLDQUERY) == 0U) &&
325 !(tried_as_is || root_on_list)) {
326 ret = res_nquerydomain(statp, name, NULL, class, type,
327 answer, anslen);
328 if (ret > 0)
329 return (ret);
330 }
331
332 /* if we got here, we didn't satisfy the search.
333 * if we did an initial full query, return that query's H_ERRNO
334 * (note that we wouldn't be here if that query had succeeded).
335 * else if we ever got a nodata, send that back as the reason.
336 * else send back meaningless H_ERRNO, that being the one from
337 * the last DNSRCH we did.
338 */
339 if (saved_herrno != -1)
340 RES_SET_H_ERRNO(statp, saved_herrno);
341 else if (got_nodata)
342 RES_SET_H_ERRNO(statp, NO_DATA);
343 else if (got_servfail)
344 RES_SET_H_ERRNO(statp, TRY_AGAIN);
345 return (-1);
346 }
347
348 /*%
349 * Perform a call on res_query on the concatenation of name and domain,
350 * removing a trailing dot from name if domain is NULL.
351 */
352 int
res_nquerydomain(res_state statp,const char * name,const char * domain,int class,int type,u_char * answer,int anslen)353 res_nquerydomain(res_state statp,
354 const char *name,
355 const char *domain,
356 int class, int type, /*%< class and type of query */
357 u_char *answer, /*%< buffer to put answer */
358 int anslen) /*%< size of answer */
359 {
360 char nbuf[MAXDNAME];
361 const char *longname = nbuf;
362 int n, d;
363
364 #ifdef DEBUG
365 if (statp->options & RES_DEBUG)
366 printf(";; res_nquerydomain(%s, %s, %d, %d)\n",
367 name, domain?domain:"<Nil>", class, type);
368 #endif
369 if (domain == NULL) {
370 /*
371 * Check for trailing '.';
372 * copy without '.' if present.
373 */
374 n = strlen(name);
375 if (n >= MAXDNAME) {
376 RES_SET_H_ERRNO(statp, NO_RECOVERY);
377 return (-1);
378 }
379 n--;
380 if (n >= 0 && name[n] == '.') {
381 strncpy(nbuf, name, n);
382 nbuf[n] = '\0';
383 } else
384 longname = name;
385 } else {
386 n = strlen(name);
387 d = strlen(domain);
388 if (n + d + 1 >= MAXDNAME) {
389 RES_SET_H_ERRNO(statp, NO_RECOVERY);
390 return (-1);
391 }
392 sprintf(nbuf, "%s.%s", name, domain);
393 }
394 return (res_nquery(statp, longname, class, type, answer, anslen));
395 }
396
397 const char *
res_hostalias(const res_state statp,const char * name,char * dst,size_t siz)398 res_hostalias(const res_state statp, const char *name, char *dst, size_t siz) {
399 char *file, *cp1, *cp2;
400 char buf[BUFSIZ];
401 FILE *fp;
402
403 if (statp->options & RES_NOALIASES)
404 return (NULL);
405 file = getenv("HOSTALIASES");
406 if (file == NULL || (fp = fopen(file, "r")) == NULL)
407 return (NULL);
408 setbuf(fp, NULL);
409 buf[sizeof(buf) - 1] = '\0';
410 while (fgets(buf, sizeof(buf), fp)) {
411 for (cp1 = buf; *cp1 && !isspace((unsigned char)*cp1); ++cp1)
412 ;
413 if (!*cp1)
414 break;
415 *cp1 = '\0';
416 if (ns_samename(buf, name) == 1) {
417 while (isspace((unsigned char)*++cp1))
418 ;
419 if (!*cp1)
420 break;
421 for (cp2 = cp1 + 1; *cp2 &&
422 !isspace((unsigned char)*cp2); ++cp2)
423 ;
424 *cp2 = '\0';
425 strncpy(dst, cp1, siz - 1);
426 dst[siz - 1] = '\0';
427 fclose(fp);
428 return (dst);
429 }
430 }
431 fclose(fp);
432 return (NULL);
433 }
434
435 /*! \file */
436