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 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 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 * If the system doesn't have _getshort/_getlong or that are not exactly what
114 * we need then use local replacements, avoiding name collisions.
115 */
116 #if !defined(HAVE__GETSHORT) || !defined(HAVE__GETLONG) || \
117 !defined(HAVE_DECL__GETSHORT) || HAVE_DECL__GETSHORT == 0 || \
118 !defined(HAVE_DECL__GETLONG) || HAVE_DECL__GETLONG == 0
119 # ifdef _getshort
120 # undef _getshort
121 # endif
122 # ifdef _getlong
123 # undef _getlong
124 # endif
125 # define _getshort(x) (_ssh_compat_getshort(x))
126 # define _getlong(x) (_ssh_compat_getlong(x))
127 /*
128 * Routines to insert/extract short/long's.
129 */
130 static u_int16_t
_getshort(const u_char * msgp)131 _getshort(const u_char *msgp)
132 {
133 u_int16_t u;
134
135 GETSHORT(u, msgp);
136 return (u);
137 }
138
139 static u_int32_t
_getlong(const u_char * msgp)140 _getlong(const u_char *msgp)
141 {
142 u_int32_t u;
143
144 GETLONG(u, msgp);
145 return (u);
146 }
147 #endif /* missing _getshort/_getlong */
148
149 /* ************** */
150
151 #define ANSWER_BUFFER_SIZE 0xffff
152
153 struct dns_query {
154 char *name;
155 u_int16_t type;
156 u_int16_t class;
157 struct dns_query *next;
158 };
159
160 struct dns_rr {
161 char *name;
162 u_int16_t type;
163 u_int16_t class;
164 u_int16_t ttl;
165 u_int16_t size;
166 void *rdata;
167 struct dns_rr *next;
168 };
169
170 struct dns_response {
171 HEADER header;
172 struct dns_query *query;
173 struct dns_rr *answer;
174 struct dns_rr *authority;
175 struct dns_rr *additional;
176 };
177
178 static struct dns_response *parse_dns_response(const u_char *, int);
179 static struct dns_query *parse_dns_qsection(const u_char *, int,
180 const u_char **, int);
181 static struct dns_rr *parse_dns_rrsection(const u_char *, int, const u_char **,
182 int);
183
184 static void free_dns_query(struct dns_query *);
185 static void free_dns_rr(struct dns_rr *);
186 static void free_dns_response(struct dns_response *);
187
188 static int count_dns_rr(struct dns_rr *, u_int16_t, u_int16_t);
189
190 int
getrrsetbyname(const char * hostname,unsigned int rdclass,unsigned int rdtype,unsigned int flags,struct rrsetinfo ** res)191 getrrsetbyname(const char *hostname, unsigned int rdclass,
192 unsigned int rdtype, unsigned int flags,
193 struct rrsetinfo **res)
194 {
195 struct __res_state *_resp = _THREAD_PRIVATE(_res, _res, &_res);
196 int result;
197 struct rrsetinfo *rrset = NULL;
198 struct dns_response *response = NULL;
199 struct dns_rr *rr;
200 struct rdatainfo *rdata;
201 int length;
202 unsigned int index_ans, index_sig;
203 u_char answer[ANSWER_BUFFER_SIZE];
204
205 /* check for invalid class and type */
206 if (rdclass > 0xffff || rdtype > 0xffff) {
207 result = ERRSET_INVAL;
208 goto fail;
209 }
210
211 /* don't allow queries of class or type ANY */
212 if (rdclass == 0xff || rdtype == 0xff) {
213 result = ERRSET_INVAL;
214 goto fail;
215 }
216
217 /* don't allow flags yet, unimplemented */
218 if (flags) {
219 result = ERRSET_INVAL;
220 goto fail;
221 }
222
223 /* initialize resolver */
224 if ((_resp->options & RES_INIT) == 0 && res_init() == -1) {
225 result = ERRSET_FAIL;
226 goto fail;
227 }
228
229 #ifdef DEBUG
230 _resp->options |= RES_DEBUG;
231 #endif /* DEBUG */
232
233 #ifdef RES_USE_DNSSEC
234 /* turn on DNSSEC if EDNS0 is configured */
235 if (_resp->options & RES_USE_EDNS0)
236 _resp->options |= RES_USE_DNSSEC;
237 #endif /* RES_USE_DNSEC */
238
239 /* make query */
240 length = res_query(hostname, (signed int) rdclass, (signed int) rdtype,
241 answer, sizeof(answer));
242 if (length < 0) {
243 switch(h_errno) {
244 case HOST_NOT_FOUND:
245 result = ERRSET_NONAME;
246 goto fail;
247 case NO_DATA:
248 result = ERRSET_NODATA;
249 goto fail;
250 default:
251 result = ERRSET_FAIL;
252 goto fail;
253 }
254 }
255
256 /* parse result */
257 response = parse_dns_response(answer, length);
258 if (response == NULL) {
259 result = ERRSET_FAIL;
260 goto fail;
261 }
262
263 if (response->header.qdcount != 1) {
264 result = ERRSET_FAIL;
265 goto fail;
266 }
267
268 /* initialize rrset */
269 rrset = calloc(1, sizeof(struct rrsetinfo));
270 if (rrset == NULL) {
271 result = ERRSET_NOMEMORY;
272 goto fail;
273 }
274 rrset->rri_rdclass = response->query->class;
275 rrset->rri_rdtype = response->query->type;
276 rrset->rri_ttl = response->answer->ttl;
277 rrset->rri_nrdatas = response->header.ancount;
278
279 #ifdef HAVE_HEADER_AD
280 /* check for authenticated data */
281 if (response->header.ad == 1)
282 rrset->rri_flags |= RRSET_VALIDATED;
283 #endif
284
285 /* copy name from answer section */
286 rrset->rri_name = strdup(response->answer->name);
287 if (rrset->rri_name == NULL) {
288 result = ERRSET_NOMEMORY;
289 goto fail;
290 }
291
292 /* count answers */
293 rrset->rri_nrdatas = count_dns_rr(response->answer, rrset->rri_rdclass,
294 rrset->rri_rdtype);
295 rrset->rri_nsigs = count_dns_rr(response->answer, rrset->rri_rdclass,
296 T_RRSIG);
297
298 /* allocate memory for answers */
299 rrset->rri_rdatas = calloc(rrset->rri_nrdatas,
300 sizeof(struct rdatainfo));
301 if (rrset->rri_rdatas == NULL) {
302 result = ERRSET_NOMEMORY;
303 goto fail;
304 }
305
306 /* allocate memory for signatures */
307 if (rrset->rri_nsigs > 0) {
308 rrset->rri_sigs = calloc(rrset->rri_nsigs, sizeof(struct rdatainfo));
309 if (rrset->rri_sigs == NULL) {
310 result = ERRSET_NOMEMORY;
311 goto fail;
312 }
313 }
314
315 /* copy answers & signatures */
316 for (rr = response->answer, index_ans = 0, index_sig = 0;
317 rr; rr = rr->next) {
318
319 rdata = NULL;
320
321 if (rr->class == rrset->rri_rdclass &&
322 rr->type == rrset->rri_rdtype)
323 rdata = &rrset->rri_rdatas[index_ans++];
324
325 if (rr->class == rrset->rri_rdclass &&
326 rr->type == T_RRSIG)
327 rdata = &rrset->rri_sigs[index_sig++];
328
329 if (rdata) {
330 rdata->rdi_length = rr->size;
331 if (rr->size != 0) {
332 rdata->rdi_data = malloc(rr->size);
333 if (rdata->rdi_data == NULL) {
334 result = ERRSET_NOMEMORY;
335 goto fail;
336 }
337 memcpy(rdata->rdi_data, rr->rdata, rr->size);
338 }
339 }
340 }
341 free_dns_response(response);
342
343 *res = rrset;
344 return (ERRSET_SUCCESS);
345
346 fail:
347 if (rrset != NULL)
348 freerrset(rrset);
349 if (response != NULL)
350 free_dns_response(response);
351 return (result);
352 }
353
354 void
freerrset(struct rrsetinfo * rrset)355 freerrset(struct rrsetinfo *rrset)
356 {
357 u_int16_t i;
358
359 if (rrset == NULL)
360 return;
361
362 if (rrset->rri_rdatas) {
363 for (i = 0; i < rrset->rri_nrdatas; i++) {
364 if (rrset->rri_rdatas[i].rdi_data == NULL)
365 break;
366 free(rrset->rri_rdatas[i].rdi_data);
367 }
368 free(rrset->rri_rdatas);
369 }
370
371 if (rrset->rri_sigs) {
372 for (i = 0; i < rrset->rri_nsigs; i++) {
373 if (rrset->rri_sigs[i].rdi_data == NULL)
374 break;
375 free(rrset->rri_sigs[i].rdi_data);
376 }
377 free(rrset->rri_sigs);
378 }
379
380 if (rrset->rri_name)
381 free(rrset->rri_name);
382 free(rrset);
383 }
384
385 /*
386 * DNS response parsing routines
387 */
388 static struct dns_response *
parse_dns_response(const u_char * answer,int size)389 parse_dns_response(const u_char *answer, int size)
390 {
391 struct dns_response *resp;
392 const u_char *cp;
393
394 if (size < HFIXEDSZ)
395 return (NULL);
396
397 /* allocate memory for the response */
398 resp = calloc(1, sizeof(*resp));
399 if (resp == NULL)
400 return (NULL);
401
402 /* initialize current pointer */
403 cp = answer;
404
405 /* copy header */
406 memcpy(&resp->header, cp, HFIXEDSZ);
407 cp += HFIXEDSZ;
408
409 /* fix header byte order */
410 resp->header.qdcount = ntohs(resp->header.qdcount);
411 resp->header.ancount = ntohs(resp->header.ancount);
412 resp->header.nscount = ntohs(resp->header.nscount);
413 resp->header.arcount = ntohs(resp->header.arcount);
414
415 /* there must be at least one query */
416 if (resp->header.qdcount < 1) {
417 free_dns_response(resp);
418 return (NULL);
419 }
420
421 /* parse query section */
422 resp->query = parse_dns_qsection(answer, size, &cp,
423 resp->header.qdcount);
424 if (resp->header.qdcount && resp->query == NULL) {
425 free_dns_response(resp);
426 return (NULL);
427 }
428
429 /* parse answer section */
430 resp->answer = parse_dns_rrsection(answer, size, &cp,
431 resp->header.ancount);
432 if (resp->header.ancount && resp->answer == NULL) {
433 free_dns_response(resp);
434 return (NULL);
435 }
436
437 /* parse authority section */
438 resp->authority = parse_dns_rrsection(answer, size, &cp,
439 resp->header.nscount);
440 if (resp->header.nscount && resp->authority == NULL) {
441 free_dns_response(resp);
442 return (NULL);
443 }
444
445 /* parse additional section */
446 resp->additional = parse_dns_rrsection(answer, size, &cp,
447 resp->header.arcount);
448 if (resp->header.arcount && resp->additional == NULL) {
449 free_dns_response(resp);
450 return (NULL);
451 }
452
453 return (resp);
454 }
455
456 static struct dns_query *
parse_dns_qsection(const u_char * answer,int size,const u_char ** cp,int count)457 parse_dns_qsection(const u_char *answer, int size, const u_char **cp, int count)
458 {
459 struct dns_query *head, *curr, *prev;
460 int i, length;
461 char name[MAXDNAME];
462
463 #define NEED(need) \
464 do { \
465 if (*cp + need > answer + size) \
466 goto fail; \
467 } while (0)
468
469 for (i = 1, head = NULL, prev = NULL; i <= count; i++, prev = curr) {
470 if (*cp >= answer + size) {
471 fail:
472 free_dns_query(head);
473 return (NULL);
474 }
475 /* allocate and initialize struct */
476 curr = calloc(1, sizeof(struct dns_query));
477 if (curr == NULL)
478 goto fail;
479 if (head == NULL)
480 head = curr;
481 if (prev != NULL)
482 prev->next = curr;
483
484 /* name */
485 length = dn_expand(answer, answer + size, *cp, name,
486 sizeof(name));
487 if (length < 0) {
488 free_dns_query(head);
489 return (NULL);
490 }
491 curr->name = strdup(name);
492 if (curr->name == NULL) {
493 free_dns_query(head);
494 return (NULL);
495 }
496 NEED(length);
497 *cp += length;
498
499 /* type */
500 NEED(INT16SZ);
501 curr->type = _getshort(*cp);
502 *cp += INT16SZ;
503
504 /* class */
505 NEED(INT16SZ);
506 curr->class = _getshort(*cp);
507 *cp += INT16SZ;
508 }
509 #undef NEED
510
511 return (head);
512 }
513
514 static struct dns_rr *
parse_dns_rrsection(const u_char * answer,int size,const u_char ** cp,int count)515 parse_dns_rrsection(const u_char *answer, int size, const u_char **cp,
516 int count)
517 {
518 struct dns_rr *head, *curr, *prev;
519 int i, length;
520 char name[MAXDNAME];
521
522 #define NEED(need) \
523 do { \
524 if (*cp + need > answer + size) \
525 goto fail; \
526 } while (0)
527
528 for (i = 1, head = NULL, prev = NULL; i <= count; i++, prev = curr) {
529 if (*cp >= answer + size) {
530 fail:
531 free_dns_rr(head);
532 return (NULL);
533 }
534
535 /* allocate and initialize struct */
536 curr = calloc(1, sizeof(struct dns_rr));
537 if (curr == NULL)
538 goto fail;
539 if (head == NULL)
540 head = curr;
541 if (prev != NULL)
542 prev->next = curr;
543
544 /* name */
545 length = dn_expand(answer, answer + size, *cp, name,
546 sizeof(name));
547 if (length < 0) {
548 free_dns_rr(head);
549 return (NULL);
550 }
551 curr->name = strdup(name);
552 if (curr->name == NULL) {
553 free_dns_rr(head);
554 return (NULL);
555 }
556 NEED(length);
557 *cp += length;
558
559 /* type */
560 NEED(INT16SZ);
561 curr->type = _getshort(*cp);
562 *cp += INT16SZ;
563
564 /* class */
565 NEED(INT16SZ);
566 curr->class = _getshort(*cp);
567 *cp += INT16SZ;
568
569 /* ttl */
570 NEED(INT32SZ);
571 curr->ttl = _getlong(*cp);
572 *cp += INT32SZ;
573
574 /* rdata size */
575 NEED(INT16SZ);
576 curr->size = _getshort(*cp);
577 *cp += INT16SZ;
578
579 /* rdata itself */
580 NEED(curr->size);
581 if (curr->size != 0) {
582 if ((curr->rdata = malloc(curr->size)) == NULL) {
583 free_dns_rr(head);
584 return (NULL);
585 }
586 memcpy(curr->rdata, *cp, curr->size);
587 }
588 *cp += curr->size;
589 }
590 #undef NEED
591
592 return (head);
593 }
594
595 static void
free_dns_query(struct dns_query * p)596 free_dns_query(struct dns_query *p)
597 {
598 if (p == NULL)
599 return;
600
601 if (p->name)
602 free(p->name);
603 free_dns_query(p->next);
604 free(p);
605 }
606
607 static void
free_dns_rr(struct dns_rr * p)608 free_dns_rr(struct dns_rr *p)
609 {
610 if (p == NULL)
611 return;
612
613 if (p->name)
614 free(p->name);
615 if (p->rdata)
616 free(p->rdata);
617 free_dns_rr(p->next);
618 free(p);
619 }
620
621 static void
free_dns_response(struct dns_response * p)622 free_dns_response(struct dns_response *p)
623 {
624 if (p == NULL)
625 return;
626
627 free_dns_query(p->query);
628 free_dns_rr(p->answer);
629 free_dns_rr(p->authority);
630 free_dns_rr(p->additional);
631 free(p);
632 }
633
634 static int
count_dns_rr(struct dns_rr * p,u_int16_t class,u_int16_t type)635 count_dns_rr(struct dns_rr *p, u_int16_t class, u_int16_t type)
636 {
637 int n = 0;
638
639 while(p) {
640 if (p->class == class && p->type == type)
641 n++;
642 p = p->next;
643 }
644
645 return (n);
646 }
647
648 #endif /* !defined (HAVE_GETRRSETBYNAME) && !defined (HAVE_LDNS) */
649