1 /* $OpenBSD: getrrsetbyname.c,v 1.11 2007/10/11 18:36:41 jakob Exp $ */
2
3 /*
4 * Copyright (c) 2001 Jakob Schlyter. All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 *
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 *
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 */
28
29 /*
30 * Portions Copyright (c) 1999-2001 Internet Software Consortium.
31 *
32 * Permission to use, copy, modify, and distribute this software for any
33 * purpose with or without fee is hereby granted, provided that the above
34 * copyright notice and this permission notice appear in all copies.
35 *
36 * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM
37 * DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL
38 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL
39 * INTERNET SOFTWARE CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT,
40 * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING
41 * FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
42 * NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
43 * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
44 */
45
46 /* OPENBSD ORIGINAL: lib/libc/net/getrrsetbyname.c */
47
48 #include "includes.h"
49
50 #if !defined (HAVE_GETRRSETBYNAME) && !defined (HAVE_LDNS)
51
52 #include <stdlib.h>
53 #include <string.h>
54
55 #include <netinet/in.h>
56 #include <arpa/inet.h>
57
58 #include "getrrsetbyname.h"
59
60 #if defined(HAVE_DECL_H_ERRNO) && !HAVE_DECL_H_ERRNO
61 extern int h_errno;
62 #endif
63
64 /* We don't need multithread support here */
65 #ifdef _THREAD_PRIVATE
66 # undef _THREAD_PRIVATE
67 #endif
68 #define _THREAD_PRIVATE(a,b,c) (c)
69
70 #ifndef HAVE__RES_EXTERN
71 struct __res_state _res;
72 #endif
73
74 /* Necessary functions and macros */
75
76 /*
77 * Inline versions of get/put short/long. Pointer is advanced.
78 *
79 * These macros demonstrate the property of C whereby it can be
80 * portable or it can be elegant but rarely both.
81 */
82
83 #ifndef INT32SZ
84 # define INT32SZ 4
85 #endif
86 #ifndef INT16SZ
87 # define INT16SZ 2
88 #endif
89
90 #ifndef GETSHORT
91 #define GETSHORT(s, cp) { \
92 register u_char *t_cp = (u_char *)(cp); \
93 (s) = ((u_int16_t)t_cp[0] << 8) \
94 | ((u_int16_t)t_cp[1]) \
95 ; \
96 (cp) += INT16SZ; \
97 }
98 #endif
99
100 #ifndef GETLONG
101 #define GETLONG(l, cp) { \
102 register u_char *t_cp = (u_char *)(cp); \
103 (l) = ((u_int32_t)t_cp[0] << 24) \
104 | ((u_int32_t)t_cp[1] << 16) \
105 | ((u_int32_t)t_cp[2] << 8) \
106 | ((u_int32_t)t_cp[3]) \
107 ; \
108 (cp) += INT32SZ; \
109 }
110 #endif
111
112 /*
113 * Routines to insert/extract short/long's.
114 */
115
116 #ifndef HAVE__GETSHORT
117 static u_int16_t
_getshort(msgp)118 _getshort(msgp)
119 register const u_char *msgp;
120 {
121 register u_int16_t u;
122
123 GETSHORT(u, msgp);
124 return (u);
125 }
126 #elif defined(HAVE_DECL__GETSHORT) && (HAVE_DECL__GETSHORT == 0)
127 u_int16_t _getshort(register const u_char *);
128 #endif
129
130 #ifndef HAVE__GETLONG
131 static u_int32_t
_getlong(msgp)132 _getlong(msgp)
133 register const u_char *msgp;
134 {
135 register u_int32_t u;
136
137 GETLONG(u, msgp);
138 return (u);
139 }
140 #elif defined(HAVE_DECL__GETLONG) && (HAVE_DECL__GETLONG == 0)
141 u_int32_t _getlong(register const u_char *);
142 #endif
143
144 /* ************** */
145
146 #define ANSWER_BUFFER_SIZE 0xffff
147
148 struct dns_query {
149 char *name;
150 u_int16_t type;
151 u_int16_t class;
152 struct dns_query *next;
153 };
154
155 struct dns_rr {
156 char *name;
157 u_int16_t type;
158 u_int16_t class;
159 u_int16_t ttl;
160 u_int16_t size;
161 void *rdata;
162 struct dns_rr *next;
163 };
164
165 struct dns_response {
166 HEADER header;
167 struct dns_query *query;
168 struct dns_rr *answer;
169 struct dns_rr *authority;
170 struct dns_rr *additional;
171 };
172
173 static struct dns_response *parse_dns_response(const u_char *, int);
174 static struct dns_query *parse_dns_qsection(const u_char *, int,
175 const u_char **, int);
176 static struct dns_rr *parse_dns_rrsection(const u_char *, int, const u_char **,
177 int);
178
179 static void free_dns_query(struct dns_query *);
180 static void free_dns_rr(struct dns_rr *);
181 static void free_dns_response(struct dns_response *);
182
183 static int count_dns_rr(struct dns_rr *, u_int16_t, u_int16_t);
184
185 int
getrrsetbyname(const char * hostname,unsigned int rdclass,unsigned int rdtype,unsigned int flags,struct rrsetinfo ** res)186 getrrsetbyname(const char *hostname, unsigned int rdclass,
187 unsigned int rdtype, unsigned int flags,
188 struct rrsetinfo **res)
189 {
190 struct __res_state *_resp = _THREAD_PRIVATE(_res, _res, &_res);
191 int result;
192 struct rrsetinfo *rrset = NULL;
193 struct dns_response *response = NULL;
194 struct dns_rr *rr;
195 struct rdatainfo *rdata;
196 int length;
197 unsigned int index_ans, index_sig;
198 u_char answer[ANSWER_BUFFER_SIZE];
199
200 /* check for invalid class and type */
201 if (rdclass > 0xffff || rdtype > 0xffff) {
202 result = ERRSET_INVAL;
203 goto fail;
204 }
205
206 /* don't allow queries of class or type ANY */
207 if (rdclass == 0xff || rdtype == 0xff) {
208 result = ERRSET_INVAL;
209 goto fail;
210 }
211
212 /* don't allow flags yet, unimplemented */
213 if (flags) {
214 result = ERRSET_INVAL;
215 goto fail;
216 }
217
218 /* initialize resolver */
219 if ((_resp->options & RES_INIT) == 0 && res_init() == -1) {
220 result = ERRSET_FAIL;
221 goto fail;
222 }
223
224 #ifdef DEBUG
225 _resp->options |= RES_DEBUG;
226 #endif /* DEBUG */
227
228 #ifdef RES_USE_DNSSEC
229 /* turn on DNSSEC if EDNS0 is configured */
230 if (_resp->options & RES_USE_EDNS0)
231 _resp->options |= RES_USE_DNSSEC;
232 #endif /* RES_USE_DNSEC */
233
234 /* make query */
235 length = res_query(hostname, (signed int) rdclass, (signed int) rdtype,
236 answer, sizeof(answer));
237 if (length < 0) {
238 switch(h_errno) {
239 case HOST_NOT_FOUND:
240 result = ERRSET_NONAME;
241 goto fail;
242 case NO_DATA:
243 result = ERRSET_NODATA;
244 goto fail;
245 default:
246 result = ERRSET_FAIL;
247 goto fail;
248 }
249 }
250
251 /* parse result */
252 response = parse_dns_response(answer, length);
253 if (response == NULL) {
254 result = ERRSET_FAIL;
255 goto fail;
256 }
257
258 if (response->header.qdcount != 1) {
259 result = ERRSET_FAIL;
260 goto fail;
261 }
262
263 /* initialize rrset */
264 rrset = calloc(1, sizeof(struct rrsetinfo));
265 if (rrset == NULL) {
266 result = ERRSET_NOMEMORY;
267 goto fail;
268 }
269 rrset->rri_rdclass = response->query->class;
270 rrset->rri_rdtype = response->query->type;
271 rrset->rri_ttl = response->answer->ttl;
272 rrset->rri_nrdatas = response->header.ancount;
273
274 #ifdef HAVE_HEADER_AD
275 /* check for authenticated data */
276 if (response->header.ad == 1)
277 rrset->rri_flags |= RRSET_VALIDATED;
278 #endif
279
280 /* copy name from answer section */
281 rrset->rri_name = strdup(response->answer->name);
282 if (rrset->rri_name == NULL) {
283 result = ERRSET_NOMEMORY;
284 goto fail;
285 }
286
287 /* count answers */
288 rrset->rri_nrdatas = count_dns_rr(response->answer, rrset->rri_rdclass,
289 rrset->rri_rdtype);
290 rrset->rri_nsigs = count_dns_rr(response->answer, rrset->rri_rdclass,
291 T_RRSIG);
292
293 /* allocate memory for answers */
294 rrset->rri_rdatas = calloc(rrset->rri_nrdatas,
295 sizeof(struct rdatainfo));
296 if (rrset->rri_rdatas == NULL) {
297 result = ERRSET_NOMEMORY;
298 goto fail;
299 }
300
301 /* allocate memory for signatures */
302 if (rrset->rri_nsigs > 0) {
303 rrset->rri_sigs = calloc(rrset->rri_nsigs, sizeof(struct rdatainfo));
304 if (rrset->rri_sigs == NULL) {
305 result = ERRSET_NOMEMORY;
306 goto fail;
307 }
308 }
309
310 /* copy answers & signatures */
311 for (rr = response->answer, index_ans = 0, index_sig = 0;
312 rr; rr = rr->next) {
313
314 rdata = NULL;
315
316 if (rr->class == rrset->rri_rdclass &&
317 rr->type == rrset->rri_rdtype)
318 rdata = &rrset->rri_rdatas[index_ans++];
319
320 if (rr->class == rrset->rri_rdclass &&
321 rr->type == T_RRSIG)
322 rdata = &rrset->rri_sigs[index_sig++];
323
324 if (rdata) {
325 rdata->rdi_length = rr->size;
326 rdata->rdi_data = malloc(rr->size);
327
328 if (rdata->rdi_data == NULL) {
329 result = ERRSET_NOMEMORY;
330 goto fail;
331 }
332 memcpy(rdata->rdi_data, rr->rdata, rr->size);
333 }
334 }
335 free_dns_response(response);
336
337 *res = rrset;
338 return (ERRSET_SUCCESS);
339
340 fail:
341 if (rrset != NULL)
342 freerrset(rrset);
343 if (response != NULL)
344 free_dns_response(response);
345 return (result);
346 }
347
348 void
freerrset(struct rrsetinfo * rrset)349 freerrset(struct rrsetinfo *rrset)
350 {
351 u_int16_t i;
352
353 if (rrset == NULL)
354 return;
355
356 if (rrset->rri_rdatas) {
357 for (i = 0; i < rrset->rri_nrdatas; i++) {
358 if (rrset->rri_rdatas[i].rdi_data == NULL)
359 break;
360 free(rrset->rri_rdatas[i].rdi_data);
361 }
362 free(rrset->rri_rdatas);
363 }
364
365 if (rrset->rri_sigs) {
366 for (i = 0; i < rrset->rri_nsigs; i++) {
367 if (rrset->rri_sigs[i].rdi_data == NULL)
368 break;
369 free(rrset->rri_sigs[i].rdi_data);
370 }
371 free(rrset->rri_sigs);
372 }
373
374 if (rrset->rri_name)
375 free(rrset->rri_name);
376 free(rrset);
377 }
378
379 /*
380 * DNS response parsing routines
381 */
382 static struct dns_response *
parse_dns_response(const u_char * answer,int size)383 parse_dns_response(const u_char *answer, int size)
384 {
385 struct dns_response *resp;
386 const u_char *cp;
387
388 /* allocate memory for the response */
389 resp = calloc(1, sizeof(*resp));
390 if (resp == NULL)
391 return (NULL);
392
393 /* initialize current pointer */
394 cp = answer;
395
396 /* copy header */
397 memcpy(&resp->header, cp, HFIXEDSZ);
398 cp += HFIXEDSZ;
399
400 /* fix header byte order */
401 resp->header.qdcount = ntohs(resp->header.qdcount);
402 resp->header.ancount = ntohs(resp->header.ancount);
403 resp->header.nscount = ntohs(resp->header.nscount);
404 resp->header.arcount = ntohs(resp->header.arcount);
405
406 /* there must be at least one query */
407 if (resp->header.qdcount < 1) {
408 free_dns_response(resp);
409 return (NULL);
410 }
411
412 /* parse query section */
413 resp->query = parse_dns_qsection(answer, size, &cp,
414 resp->header.qdcount);
415 if (resp->header.qdcount && resp->query == NULL) {
416 free_dns_response(resp);
417 return (NULL);
418 }
419
420 /* parse answer section */
421 resp->answer = parse_dns_rrsection(answer, size, &cp,
422 resp->header.ancount);
423 if (resp->header.ancount && resp->answer == NULL) {
424 free_dns_response(resp);
425 return (NULL);
426 }
427
428 /* parse authority section */
429 resp->authority = parse_dns_rrsection(answer, size, &cp,
430 resp->header.nscount);
431 if (resp->header.nscount && resp->authority == NULL) {
432 free_dns_response(resp);
433 return (NULL);
434 }
435
436 /* parse additional section */
437 resp->additional = parse_dns_rrsection(answer, size, &cp,
438 resp->header.arcount);
439 if (resp->header.arcount && resp->additional == NULL) {
440 free_dns_response(resp);
441 return (NULL);
442 }
443
444 return (resp);
445 }
446
447 static struct dns_query *
parse_dns_qsection(const u_char * answer,int size,const u_char ** cp,int count)448 parse_dns_qsection(const u_char *answer, int size, const u_char **cp, int count)
449 {
450 struct dns_query *head, *curr, *prev;
451 int i, length;
452 char name[MAXDNAME];
453
454 for (i = 1, head = NULL, prev = NULL; i <= count; i++, prev = curr) {
455
456 /* allocate and initialize struct */
457 curr = calloc(1, sizeof(struct dns_query));
458 if (curr == NULL) {
459 free_dns_query(head);
460 return (NULL);
461 }
462 if (head == NULL)
463 head = curr;
464 if (prev != NULL)
465 prev->next = curr;
466
467 /* name */
468 length = dn_expand(answer, answer + size, *cp, name,
469 sizeof(name));
470 if (length < 0) {
471 free_dns_query(head);
472 return (NULL);
473 }
474 curr->name = strdup(name);
475 if (curr->name == NULL) {
476 free_dns_query(head);
477 return (NULL);
478 }
479 *cp += length;
480
481 /* type */
482 curr->type = _getshort(*cp);
483 *cp += INT16SZ;
484
485 /* class */
486 curr->class = _getshort(*cp);
487 *cp += INT16SZ;
488 }
489
490 return (head);
491 }
492
493 static struct dns_rr *
parse_dns_rrsection(const u_char * answer,int size,const u_char ** cp,int count)494 parse_dns_rrsection(const u_char *answer, int size, const u_char **cp,
495 int count)
496 {
497 struct dns_rr *head, *curr, *prev;
498 int i, length;
499 char name[MAXDNAME];
500
501 for (i = 1, head = NULL, prev = NULL; i <= count; i++, prev = curr) {
502
503 /* allocate and initialize struct */
504 curr = calloc(1, sizeof(struct dns_rr));
505 if (curr == NULL) {
506 free_dns_rr(head);
507 return (NULL);
508 }
509 if (head == NULL)
510 head = curr;
511 if (prev != NULL)
512 prev->next = curr;
513
514 /* name */
515 length = dn_expand(answer, answer + size, *cp, name,
516 sizeof(name));
517 if (length < 0) {
518 free_dns_rr(head);
519 return (NULL);
520 }
521 curr->name = strdup(name);
522 if (curr->name == NULL) {
523 free_dns_rr(head);
524 return (NULL);
525 }
526 *cp += length;
527
528 /* type */
529 curr->type = _getshort(*cp);
530 *cp += INT16SZ;
531
532 /* class */
533 curr->class = _getshort(*cp);
534 *cp += INT16SZ;
535
536 /* ttl */
537 curr->ttl = _getlong(*cp);
538 *cp += INT32SZ;
539
540 /* rdata size */
541 curr->size = _getshort(*cp);
542 *cp += INT16SZ;
543
544 /* rdata itself */
545 curr->rdata = malloc(curr->size);
546 if (curr->rdata == NULL) {
547 free_dns_rr(head);
548 return (NULL);
549 }
550 memcpy(curr->rdata, *cp, curr->size);
551 *cp += curr->size;
552 }
553
554 return (head);
555 }
556
557 static void
free_dns_query(struct dns_query * p)558 free_dns_query(struct dns_query *p)
559 {
560 if (p == NULL)
561 return;
562
563 if (p->name)
564 free(p->name);
565 free_dns_query(p->next);
566 free(p);
567 }
568
569 static void
free_dns_rr(struct dns_rr * p)570 free_dns_rr(struct dns_rr *p)
571 {
572 if (p == NULL)
573 return;
574
575 if (p->name)
576 free(p->name);
577 if (p->rdata)
578 free(p->rdata);
579 free_dns_rr(p->next);
580 free(p);
581 }
582
583 static void
free_dns_response(struct dns_response * p)584 free_dns_response(struct dns_response *p)
585 {
586 if (p == NULL)
587 return;
588
589 free_dns_query(p->query);
590 free_dns_rr(p->answer);
591 free_dns_rr(p->authority);
592 free_dns_rr(p->additional);
593 free(p);
594 }
595
596 static int
count_dns_rr(struct dns_rr * p,u_int16_t class,u_int16_t type)597 count_dns_rr(struct dns_rr *p, u_int16_t class, u_int16_t type)
598 {
599 int n = 0;
600
601 while(p) {
602 if (p->class == class && p->type == type)
603 n++;
604 p = p->next;
605 }
606
607 return (n);
608 }
609
610 #endif /* !defined (HAVE_GETRRSETBYNAME) && !defined (HAVE_LDNS) */
611