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	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 */
130static u_int16_t
131_getshort(const u_char *msgp)
132{
133	u_int16_t u;
134
135	GETSHORT(u, msgp);
136	return (u);
137}
138
139static u_int32_t
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
153struct dns_query {
154	char			*name;
155	u_int16_t		type;
156	u_int16_t		class;
157	struct dns_query	*next;
158};
159
160struct 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
170struct 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
178static struct dns_response *parse_dns_response(const u_char *, int);
179static struct dns_query *parse_dns_qsection(const u_char *, int,
180    const u_char **, int);
181static struct dns_rr *parse_dns_rrsection(const u_char *, int, const u_char **,
182    int);
183
184static void free_dns_query(struct dns_query *);
185static void free_dns_rr(struct dns_rr *);
186static void free_dns_response(struct dns_response *);
187
188static int count_dns_rr(struct dns_rr *, u_int16_t, u_int16_t);
189
190int
191getrrsetbyname(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			rdata->rdi_data   = malloc(rr->size);
332
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	free_dns_response(response);
341
342	*res = rrset;
343	return (ERRSET_SUCCESS);
344
345fail:
346	if (rrset != NULL)
347		freerrset(rrset);
348	if (response != NULL)
349		free_dns_response(response);
350	return (result);
351}
352
353void
354freerrset(struct rrsetinfo *rrset)
355{
356	u_int16_t i;
357
358	if (rrset == NULL)
359		return;
360
361	if (rrset->rri_rdatas) {
362		for (i = 0; i < rrset->rri_nrdatas; i++) {
363			if (rrset->rri_rdatas[i].rdi_data == NULL)
364				break;
365			free(rrset->rri_rdatas[i].rdi_data);
366		}
367		free(rrset->rri_rdatas);
368	}
369
370	if (rrset->rri_sigs) {
371		for (i = 0; i < rrset->rri_nsigs; i++) {
372			if (rrset->rri_sigs[i].rdi_data == NULL)
373				break;
374			free(rrset->rri_sigs[i].rdi_data);
375		}
376		free(rrset->rri_sigs);
377	}
378
379	if (rrset->rri_name)
380		free(rrset->rri_name);
381	free(rrset);
382}
383
384/*
385 * DNS response parsing routines
386 */
387static struct dns_response *
388parse_dns_response(const u_char *answer, int size)
389{
390	struct dns_response *resp;
391	const u_char *cp;
392
393	if (size < HFIXEDSZ)
394		return (NULL);
395
396	/* allocate memory for the response */
397	resp = calloc(1, sizeof(*resp));
398	if (resp == NULL)
399		return (NULL);
400
401	/* initialize current pointer */
402	cp = answer;
403
404	/* copy header */
405	memcpy(&resp->header, cp, HFIXEDSZ);
406	cp += HFIXEDSZ;
407
408	/* fix header byte order */
409	resp->header.qdcount = ntohs(resp->header.qdcount);
410	resp->header.ancount = ntohs(resp->header.ancount);
411	resp->header.nscount = ntohs(resp->header.nscount);
412	resp->header.arcount = ntohs(resp->header.arcount);
413
414	/* there must be at least one query */
415	if (resp->header.qdcount < 1) {
416		free_dns_response(resp);
417		return (NULL);
418	}
419
420	/* parse query section */
421	resp->query = parse_dns_qsection(answer, size, &cp,
422	    resp->header.qdcount);
423	if (resp->header.qdcount && resp->query == NULL) {
424		free_dns_response(resp);
425		return (NULL);
426	}
427
428	/* parse answer section */
429	resp->answer = parse_dns_rrsection(answer, size, &cp,
430	    resp->header.ancount);
431	if (resp->header.ancount && resp->answer == NULL) {
432		free_dns_response(resp);
433		return (NULL);
434	}
435
436	/* parse authority section */
437	resp->authority = parse_dns_rrsection(answer, size, &cp,
438	    resp->header.nscount);
439	if (resp->header.nscount && resp->authority == NULL) {
440		free_dns_response(resp);
441		return (NULL);
442	}
443
444	/* parse additional section */
445	resp->additional = parse_dns_rrsection(answer, size, &cp,
446	    resp->header.arcount);
447	if (resp->header.arcount && resp->additional == NULL) {
448		free_dns_response(resp);
449		return (NULL);
450	}
451
452	return (resp);
453}
454
455static struct dns_query *
456parse_dns_qsection(const u_char *answer, int size, const u_char **cp, int count)
457{
458	struct dns_query *head, *curr, *prev;
459	int i, length;
460	char name[MAXDNAME];
461
462#define NEED(need) \
463	do { \
464		if (*cp + need > answer + size) \
465			goto fail; \
466	} while (0)
467
468	for (i = 1, head = NULL, prev = NULL; i <= count; i++, prev = curr) {
469		if (*cp >= answer + size) {
470 fail:
471			free_dns_query(head);
472			return (NULL);
473		}
474		/* allocate and initialize struct */
475		curr = calloc(1, sizeof(struct dns_query));
476		if (curr == NULL)
477			goto fail;
478		if (head == NULL)
479			head = curr;
480		if (prev != NULL)
481			prev->next = curr;
482
483		/* name */
484		length = dn_expand(answer, answer + size, *cp, name,
485		    sizeof(name));
486		if (length < 0) {
487			free_dns_query(head);
488			return (NULL);
489		}
490		curr->name = strdup(name);
491		if (curr->name == NULL) {
492			free_dns_query(head);
493			return (NULL);
494		}
495		NEED(length);
496		*cp += length;
497
498		/* type */
499		NEED(INT16SZ);
500		curr->type = _getshort(*cp);
501		*cp += INT16SZ;
502
503		/* class */
504		NEED(INT16SZ);
505		curr->class = _getshort(*cp);
506		*cp += INT16SZ;
507	}
508#undef NEED
509
510	return (head);
511}
512
513static struct dns_rr *
514parse_dns_rrsection(const u_char *answer, int size, const u_char **cp,
515    int count)
516{
517	struct dns_rr *head, *curr, *prev;
518	int i, length;
519	char name[MAXDNAME];
520
521#define NEED(need) \
522	do { \
523		if (*cp + need > answer + size) \
524			goto fail; \
525	} while (0)
526
527	for (i = 1, head = NULL, prev = NULL; i <= count; i++, prev = curr) {
528		if (*cp >= answer + size) {
529 fail:
530			free_dns_rr(head);
531			return (NULL);
532		}
533
534		/* allocate and initialize struct */
535		curr = calloc(1, sizeof(struct dns_rr));
536		if (curr == NULL)
537			goto fail;
538		if (head == NULL)
539			head = curr;
540		if (prev != NULL)
541			prev->next = curr;
542
543		/* name */
544		length = dn_expand(answer, answer + size, *cp, name,
545		    sizeof(name));
546		if (length < 0) {
547			free_dns_rr(head);
548			return (NULL);
549		}
550		curr->name = strdup(name);
551		if (curr->name == NULL) {
552			free_dns_rr(head);
553			return (NULL);
554		}
555		NEED(length);
556		*cp += length;
557
558		/* type */
559		NEED(INT16SZ);
560		curr->type = _getshort(*cp);
561		*cp += INT16SZ;
562
563		/* class */
564		NEED(INT16SZ);
565		curr->class = _getshort(*cp);
566		*cp += INT16SZ;
567
568		/* ttl */
569		NEED(INT32SZ);
570		curr->ttl = _getlong(*cp);
571		*cp += INT32SZ;
572
573		/* rdata size */
574		NEED(INT16SZ);
575		curr->size = _getshort(*cp);
576		*cp += INT16SZ;
577
578		/* rdata itself */
579		NEED(curr->size);
580		curr->rdata = malloc(curr->size);
581		if (curr->rdata == NULL) {
582			free_dns_rr(head);
583			return (NULL);
584		}
585		memcpy(curr->rdata, *cp, curr->size);
586		*cp += curr->size;
587	}
588#undef NEED
589
590	return (head);
591}
592
593static void
594free_dns_query(struct dns_query *p)
595{
596	if (p == NULL)
597		return;
598
599	if (p->name)
600		free(p->name);
601	free_dns_query(p->next);
602	free(p);
603}
604
605static void
606free_dns_rr(struct dns_rr *p)
607{
608	if (p == NULL)
609		return;
610
611	if (p->name)
612		free(p->name);
613	if (p->rdata)
614		free(p->rdata);
615	free_dns_rr(p->next);
616	free(p);
617}
618
619static void
620free_dns_response(struct dns_response *p)
621{
622	if (p == NULL)
623		return;
624
625	free_dns_query(p->query);
626	free_dns_rr(p->answer);
627	free_dns_rr(p->authority);
628	free_dns_rr(p->additional);
629	free(p);
630}
631
632static int
633count_dns_rr(struct dns_rr *p, u_int16_t class, u_int16_t type)
634{
635	int n = 0;
636
637	while(p) {
638		if (p->class == class && p->type == type)
639			n++;
640		p = p->next;
641	}
642
643	return (n);
644}
645
646#endif /*  !defined (HAVE_GETRRSETBYNAME) && !defined (HAVE_LDNS) */
647