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
61extern 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
71struct __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
117static u_int16_t
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)
127u_int16_t _getshort(register const u_char *);
128#endif
129
130#ifndef HAVE__GETLONG
131static u_int32_t
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)
141u_int32_t _getlong(register const u_char *);
142#endif
143
144/* ************** */
145
146#define ANSWER_BUFFER_SIZE 0xffff
147
148struct dns_query {
149	char			*name;
150	u_int16_t		type;
151	u_int16_t		class;
152	struct dns_query	*next;
153};
154
155struct 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
165struct 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
173static struct dns_response *parse_dns_response(const u_char *, int);
174static struct dns_query *parse_dns_qsection(const u_char *, int,
175    const u_char **, int);
176static struct dns_rr *parse_dns_rrsection(const u_char *, int, const u_char **,
177    int);
178
179static void free_dns_query(struct dns_query *);
180static void free_dns_rr(struct dns_rr *);
181static void free_dns_response(struct dns_response *);
182
183static int count_dns_rr(struct dns_rr *, u_int16_t, u_int16_t);
184
185int
186getrrsetbyname(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
340fail:
341	if (rrset != NULL)
342		freerrset(rrset);
343	if (response != NULL)
344		free_dns_response(response);
345	return (result);
346}
347
348void
349freerrset(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 */
382static struct dns_response *
383parse_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
447static struct dns_query *
448parse_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
493static struct dns_rr *
494parse_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
557static void
558free_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
569static void
570free_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
583static void
584free_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
596static int
597count_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