getrrsetbyname.c revision 157016 
1/* $OpenBSD: getrrsetbyname.c,v 1.10 2005/03/30 02:58:28 tedu 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#ifndef HAVE_GETRRSETBYNAME
51
52#include "getrrsetbyname.h"
53
54#if defined(HAVE_DECL_H_ERRNO) && !HAVE_DECL_H_ERRNO
55extern int h_errno;
56#endif
57
58/* We don't need multithread support here */
59#ifdef _THREAD_PRIVATE
60# undef _THREAD_PRIVATE
61#endif
62#define _THREAD_PRIVATE(a,b,c) (c)
63struct __res_state _res;
64
65/* Necessary functions and macros */
66
67/*
68 * Inline versions of get/put short/long.  Pointer is advanced.
69 *
70 * These macros demonstrate the property of C whereby it can be
71 * portable or it can be elegant but rarely both.
72 */
73
74#ifndef INT32SZ
75# define INT32SZ	4
76#endif
77#ifndef INT16SZ
78# define INT16SZ	2
79#endif
80
81#ifndef GETSHORT
82#define GETSHORT(s, cp) { \
83	register u_char *t_cp = (u_char *)(cp); \
84	(s) = ((u_int16_t)t_cp[0] << 8) \
85	    | ((u_int16_t)t_cp[1]) \
86	    ; \
87	(cp) += INT16SZ; \
88}
89#endif
90
91#ifndef GETLONG
92#define GETLONG(l, cp) { \
93	register u_char *t_cp = (u_char *)(cp); \
94	(l) = ((u_int32_t)t_cp[0] << 24) \
95	    | ((u_int32_t)t_cp[1] << 16) \
96	    | ((u_int32_t)t_cp[2] << 8) \
97	    | ((u_int32_t)t_cp[3]) \
98	    ; \
99	(cp) += INT32SZ; \
100}
101#endif
102
103/*
104 * Routines to insert/extract short/long's.
105 */
106
107#ifndef HAVE__GETSHORT
108static u_int16_t
109_getshort(msgp)
110	register const u_char *msgp;
111{
112	register u_int16_t u;
113
114	GETSHORT(u, msgp);
115	return (u);
116}
117#elif defined(HAVE_DECL__GETSHORT) && (HAVE_DECL__GETSHORT == 0)
118u_int16_t _getshort(register const u_char *);
119#endif
120
121#ifndef HAVE__GETLONG
122static u_int32_t
123_getlong(msgp)
124	register const u_char *msgp;
125{
126	register u_int32_t u;
127
128	GETLONG(u, msgp);
129	return (u);
130}
131#elif defined(HAVE_DECL__GETLONG) && (HAVE_DECL__GETLONG == 0)
132u_int32_t _getlong(register const u_char *);
133#endif
134
135/* ************** */
136
137#define ANSWER_BUFFER_SIZE 1024*64
138
139struct dns_query {
140	char			*name;
141	u_int16_t		type;
142	u_int16_t		class;
143	struct dns_query	*next;
144};
145
146struct dns_rr {
147	char			*name;
148	u_int16_t		type;
149	u_int16_t		class;
150	u_int16_t		ttl;
151	u_int16_t		size;
152	void			*rdata;
153	struct dns_rr		*next;
154};
155
156struct dns_response {
157	HEADER			header;
158	struct dns_query	*query;
159	struct dns_rr		*answer;
160	struct dns_rr		*authority;
161	struct dns_rr		*additional;
162};
163
164static struct dns_response *parse_dns_response(const u_char *, int);
165static struct dns_query *parse_dns_qsection(const u_char *, int,
166    const u_char **, int);
167static struct dns_rr *parse_dns_rrsection(const u_char *, int, const u_char **,
168    int);
169
170static void free_dns_query(struct dns_query *);
171static void free_dns_rr(struct dns_rr *);
172static void free_dns_response(struct dns_response *);
173
174static int count_dns_rr(struct dns_rr *, u_int16_t, u_int16_t);
175
176int
177getrrsetbyname(const char *hostname, unsigned int rdclass,
178    unsigned int rdtype, unsigned int flags,
179    struct rrsetinfo **res)
180{
181	struct __res_state *_resp = _THREAD_PRIVATE(_res, _res, &_res);
182	int result;
183	struct rrsetinfo *rrset = NULL;
184	struct dns_response *response = NULL;
185	struct dns_rr *rr;
186	struct rdatainfo *rdata;
187	int length;
188	unsigned int index_ans, index_sig;
189	u_char answer[ANSWER_BUFFER_SIZE];
190
191	/* check for invalid class and type */
192	if (rdclass > 0xffff || rdtype > 0xffff) {
193		result = ERRSET_INVAL;
194		goto fail;
195	}
196
197	/* don't allow queries of class or type ANY */
198	if (rdclass == 0xff || rdtype == 0xff) {
199		result = ERRSET_INVAL;
200		goto fail;
201	}
202
203	/* don't allow flags yet, unimplemented */
204	if (flags) {
205		result = ERRSET_INVAL;
206		goto fail;
207	}
208
209	/* initialize resolver */
210	if ((_resp->options & RES_INIT) == 0 && res_init() == -1) {
211		result = ERRSET_FAIL;
212		goto fail;
213	}
214
215#ifdef DEBUG
216	_resp->options |= RES_DEBUG;
217#endif /* DEBUG */
218
219#ifdef RES_USE_DNSSEC
220	/* turn on DNSSEC if EDNS0 is configured */
221	if (_resp->options & RES_USE_EDNS0)
222		_resp->options |= RES_USE_DNSSEC;
223#endif /* RES_USE_DNSEC */
224
225	/* make query */
226	length = res_query(hostname, (signed int) rdclass, (signed int) rdtype,
227	    answer, sizeof(answer));
228	if (length < 0) {
229		switch(h_errno) {
230		case HOST_NOT_FOUND:
231			result = ERRSET_NONAME;
232			goto fail;
233		case NO_DATA:
234			result = ERRSET_NODATA;
235			goto fail;
236		default:
237			result = ERRSET_FAIL;
238			goto fail;
239		}
240	}
241
242	/* parse result */
243	response = parse_dns_response(answer, length);
244	if (response == NULL) {
245		result = ERRSET_FAIL;
246		goto fail;
247	}
248
249	if (response->header.qdcount != 1) {
250		result = ERRSET_FAIL;
251		goto fail;
252	}
253
254	/* initialize rrset */
255	rrset = calloc(1, sizeof(struct rrsetinfo));
256	if (rrset == NULL) {
257		result = ERRSET_NOMEMORY;
258		goto fail;
259	}
260	rrset->rri_rdclass = response->query->class;
261	rrset->rri_rdtype = response->query->type;
262	rrset->rri_ttl = response->answer->ttl;
263	rrset->rri_nrdatas = response->header.ancount;
264
265#ifdef HAVE_HEADER_AD
266	/* check for authenticated data */
267	if (response->header.ad == 1)
268		rrset->rri_flags |= RRSET_VALIDATED;
269#endif
270
271	/* copy name from answer section */
272	rrset->rri_name = strdup(response->answer->name);
273	if (rrset->rri_name == NULL) {
274		result = ERRSET_NOMEMORY;
275		goto fail;
276	}
277
278	/* count answers */
279	rrset->rri_nrdatas = count_dns_rr(response->answer, rrset->rri_rdclass,
280	    rrset->rri_rdtype);
281	rrset->rri_nsigs = count_dns_rr(response->answer, rrset->rri_rdclass,
282	    T_SIG);
283
284	/* allocate memory for answers */
285	rrset->rri_rdatas = calloc(rrset->rri_nrdatas,
286	    sizeof(struct rdatainfo));
287	if (rrset->rri_rdatas == NULL) {
288		result = ERRSET_NOMEMORY;
289		goto fail;
290	}
291
292	/* allocate memory for signatures */
293	rrset->rri_sigs = calloc(rrset->rri_nsigs, sizeof(struct rdatainfo));
294	if (rrset->rri_sigs == NULL) {
295		result = ERRSET_NOMEMORY;
296		goto fail;
297	}
298
299	/* copy answers & signatures */
300	for (rr = response->answer, index_ans = 0, index_sig = 0;
301	    rr; rr = rr->next) {
302
303		rdata = NULL;
304
305		if (rr->class == rrset->rri_rdclass &&
306		    rr->type  == rrset->rri_rdtype)
307			rdata = &rrset->rri_rdatas[index_ans++];
308
309		if (rr->class == rrset->rri_rdclass &&
310		    rr->type  == T_SIG)
311			rdata = &rrset->rri_sigs[index_sig++];
312
313		if (rdata) {
314			rdata->rdi_length = rr->size;
315			rdata->rdi_data   = malloc(rr->size);
316
317			if (rdata->rdi_data == NULL) {
318				result = ERRSET_NOMEMORY;
319				goto fail;
320			}
321			memcpy(rdata->rdi_data, rr->rdata, rr->size);
322		}
323	}
324	free_dns_response(response);
325
326	*res = rrset;
327	return (ERRSET_SUCCESS);
328
329fail:
330	if (rrset != NULL)
331		freerrset(rrset);
332	if (response != NULL)
333		free_dns_response(response);
334	return (result);
335}
336
337void
338freerrset(struct rrsetinfo *rrset)
339{
340	u_int16_t i;
341
342	if (rrset == NULL)
343		return;
344
345	if (rrset->rri_rdatas) {
346		for (i = 0; i < rrset->rri_nrdatas; i++) {
347			if (rrset->rri_rdatas[i].rdi_data == NULL)
348				break;
349			free(rrset->rri_rdatas[i].rdi_data);
350		}
351		free(rrset->rri_rdatas);
352	}
353
354	if (rrset->rri_sigs) {
355		for (i = 0; i < rrset->rri_nsigs; i++) {
356			if (rrset->rri_sigs[i].rdi_data == NULL)
357				break;
358			free(rrset->rri_sigs[i].rdi_data);
359		}
360		free(rrset->rri_sigs);
361	}
362
363	if (rrset->rri_name)
364		free(rrset->rri_name);
365	free(rrset);
366}
367
368/*
369 * DNS response parsing routines
370 */
371static struct dns_response *
372parse_dns_response(const u_char *answer, int size)
373{
374	struct dns_response *resp;
375	const u_char *cp;
376
377	/* allocate memory for the response */
378	resp = calloc(1, sizeof(*resp));
379	if (resp == NULL)
380		return (NULL);
381
382	/* initialize current pointer */
383	cp = answer;
384
385	/* copy header */
386	memcpy(&resp->header, cp, HFIXEDSZ);
387	cp += HFIXEDSZ;
388
389	/* fix header byte order */
390	resp->header.qdcount = ntohs(resp->header.qdcount);
391	resp->header.ancount = ntohs(resp->header.ancount);
392	resp->header.nscount = ntohs(resp->header.nscount);
393	resp->header.arcount = ntohs(resp->header.arcount);
394
395	/* there must be at least one query */
396	if (resp->header.qdcount < 1) {
397		free_dns_response(resp);
398		return (NULL);
399	}
400
401	/* parse query section */
402	resp->query = parse_dns_qsection(answer, size, &cp,
403	    resp->header.qdcount);
404	if (resp->header.qdcount && resp->query == NULL) {
405		free_dns_response(resp);
406		return (NULL);
407	}
408
409	/* parse answer section */
410	resp->answer = parse_dns_rrsection(answer, size, &cp,
411	    resp->header.ancount);
412	if (resp->header.ancount && resp->answer == NULL) {
413		free_dns_response(resp);
414		return (NULL);
415	}
416
417	/* parse authority section */
418	resp->authority = parse_dns_rrsection(answer, size, &cp,
419	    resp->header.nscount);
420	if (resp->header.nscount && resp->authority == NULL) {
421		free_dns_response(resp);
422		return (NULL);
423	}
424
425	/* parse additional section */
426	resp->additional = parse_dns_rrsection(answer, size, &cp,
427	    resp->header.arcount);
428	if (resp->header.arcount && resp->additional == NULL) {
429		free_dns_response(resp);
430		return (NULL);
431	}
432
433	return (resp);
434}
435
436static struct dns_query *
437parse_dns_qsection(const u_char *answer, int size, const u_char **cp, int count)
438{
439	struct dns_query *head, *curr, *prev;
440	int i, length;
441	char name[MAXDNAME];
442
443	for (i = 1, head = NULL, prev = NULL; i <= count; i++, prev = curr) {
444
445		/* allocate and initialize struct */
446		curr = calloc(1, sizeof(struct dns_query));
447		if (curr == NULL) {
448			free_dns_query(head);
449			return (NULL);
450		}
451		if (head == NULL)
452			head = curr;
453		if (prev != NULL)
454			prev->next = curr;
455
456		/* name */
457		length = dn_expand(answer, answer + size, *cp, name,
458		    sizeof(name));
459		if (length < 0) {
460			free_dns_query(head);
461			return (NULL);
462		}
463		curr->name = strdup(name);
464		if (curr->name == NULL) {
465			free_dns_query(head);
466			return (NULL);
467		}
468		*cp += length;
469
470		/* type */
471		curr->type = _getshort(*cp);
472		*cp += INT16SZ;
473
474		/* class */
475		curr->class = _getshort(*cp);
476		*cp += INT16SZ;
477	}
478
479	return (head);
480}
481
482static struct dns_rr *
483parse_dns_rrsection(const u_char *answer, int size, const u_char **cp,
484    int count)
485{
486	struct dns_rr *head, *curr, *prev;
487	int i, length;
488	char name[MAXDNAME];
489
490	for (i = 1, head = NULL, prev = NULL; i <= count; i++, prev = curr) {
491
492		/* allocate and initialize struct */
493		curr = calloc(1, sizeof(struct dns_rr));
494		if (curr == NULL) {
495			free_dns_rr(head);
496			return (NULL);
497		}
498		if (head == NULL)
499			head = curr;
500		if (prev != NULL)
501			prev->next = curr;
502
503		/* name */
504		length = dn_expand(answer, answer + size, *cp, name,
505		    sizeof(name));
506		if (length < 0) {
507			free_dns_rr(head);
508			return (NULL);
509		}
510		curr->name = strdup(name);
511		if (curr->name == NULL) {
512			free_dns_rr(head);
513			return (NULL);
514		}
515		*cp += length;
516
517		/* type */
518		curr->type = _getshort(*cp);
519		*cp += INT16SZ;
520
521		/* class */
522		curr->class = _getshort(*cp);
523		*cp += INT16SZ;
524
525		/* ttl */
526		curr->ttl = _getlong(*cp);
527		*cp += INT32SZ;
528
529		/* rdata size */
530		curr->size = _getshort(*cp);
531		*cp += INT16SZ;
532
533		/* rdata itself */
534		curr->rdata = malloc(curr->size);
535		if (curr->rdata == NULL) {
536			free_dns_rr(head);
537			return (NULL);
538		}
539		memcpy(curr->rdata, *cp, curr->size);
540		*cp += curr->size;
541	}
542
543	return (head);
544}
545
546static void
547free_dns_query(struct dns_query *p)
548{
549	if (p == NULL)
550		return;
551
552	if (p->name)
553		free(p->name);
554	free_dns_query(p->next);
555	free(p);
556}
557
558static void
559free_dns_rr(struct dns_rr *p)
560{
561	if (p == NULL)
562		return;
563
564	if (p->name)
565		free(p->name);
566	if (p->rdata)
567		free(p->rdata);
568	free_dns_rr(p->next);
569	free(p);
570}
571
572static void
573free_dns_response(struct dns_response *p)
574{
575	if (p == NULL)
576		return;
577
578	free_dns_query(p->query);
579	free_dns_rr(p->answer);
580	free_dns_rr(p->authority);
581	free_dns_rr(p->additional);
582	free(p);
583}
584
585static int
586count_dns_rr(struct dns_rr *p, u_int16_t class, u_int16_t type)
587{
588	int n = 0;
589
590	while(p) {
591		if (p->class == class && p->type == type)
592			n++;
593		p = p->next;
594	}
595
596	return (n);
597}
598
599#endif /* !defined(HAVE_GETRRSETBYNAME) */
600