1/*	$NetBSD: getrrsetbyname.c,v 1.6 2020/11/12 19:43:18 christos Exp $	*/
2/* $OpenBSD: getrrsetbyname.c,v 1.10 2005/03/30 02:58:28 tedu Exp $ */
3
4/*
5 * Copyright (c) 2001 Jakob Schlyter. All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 *
11 * 1. Redistributions of source code must retain the above copyright
12 *    notice, this list of conditions and the following disclaimer.
13 *
14 * 2. Redistributions in binary form must reproduce the above copyright
15 *    notice, this list of conditions and the following disclaimer in the
16 *    documentation and/or other materials provided with the distribution.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
19 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
20 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
21 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
22 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
23 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
24 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
25 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
26 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
27 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28 */
29
30/*
31 * Portions Copyright (c) 1999-2001 Internet Software Consortium.
32 *
33 * Permission to use, copy, modify, and distribute this software for any
34 * purpose with or without fee is hereby granted, provided that the above
35 * copyright notice and this permission notice appear in all copies.
36 *
37 * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM
38 * DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL
39 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL
40 * INTERNET SOFTWARE CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT,
41 * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING
42 * FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
43 * NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
44 * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
45 */
46
47/* OPENBSD ORIGINAL: lib/libc/net/getrrsetbyname.c */
48
49#include "includes.h"
50__RCSID("$NetBSD: getrrsetbyname.c,v 1.6 2020/11/12 19:43:18 christos Exp $");
51
52#ifndef HAVE_GETRRSETBYNAME
53
54#include <string.h>
55#include <stdlib.h>
56#include <unistd.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#ifndef __NetBSD__
70struct __res_state _res;
71#else
72#define HAVE__GETSHORT
73#define HAVE__GETLONG
74#endif
75
76/* Necessary functions and macros */
77
78/*
79 * Inline versions of get/put short/long.  Pointer is advanced.
80 *
81 * These macros demonstrate the property of C whereby it can be
82 * portable or it can be elegant but rarely both.
83 */
84
85#ifndef INT32SZ
86# define INT32SZ	4
87#endif
88#ifndef INT16SZ
89# define INT16SZ	2
90#endif
91
92#ifndef GETSHORT
93#define GETSHORT(s, cp) { \
94	register u_char *t_cp = (u_char *)(cp); \
95	(s) = ((u_int16_t)t_cp[0] << 8) \
96	    | ((u_int16_t)t_cp[1]) \
97	    ; \
98	(cp) += INT16SZ; \
99}
100#endif
101
102#ifndef GETLONG
103#define GETLONG(l, cp) { \
104	register u_char *t_cp = (u_char *)(cp); \
105	(l) = ((u_int32_t)t_cp[0] << 24) \
106	    | ((u_int32_t)t_cp[1] << 16) \
107	    | ((u_int32_t)t_cp[2] << 8) \
108	    | ((u_int32_t)t_cp[3]) \
109	    ; \
110	(cp) += INT32SZ; \
111}
112#endif
113
114/*
115 * Routines to insert/extract short/long's.
116 */
117
118#ifndef HAVE__GETSHORT
119static u_int16_t
120_getshort(msgp)
121	register const u_char *msgp;
122{
123	register u_int16_t u;
124
125	GETSHORT(u, msgp);
126	return (u);
127}
128#elif defined(HAVE_DECL__GETSHORT) && (HAVE_DECL__GETSHORT == 0)
129u_int16_t _getshort(register const u_char *);
130#endif
131
132#ifndef HAVE__GETLONG
133static u_int32_t
134_getlong(msgp)
135	register const u_char *msgp;
136{
137	register u_int32_t u;
138
139	GETLONG(u, msgp);
140	return (u);
141}
142#elif defined(HAVE_DECL__GETLONG) && (HAVE_DECL__GETLONG == 0)
143u_int32_t _getlong(register const u_char *);
144#endif
145
146/* ************** */
147
148#define ANSWER_BUFFER_SIZE 1024*64
149
150struct dns_query {
151	char			*name;
152	u_int16_t		type;
153	u_int16_t		class;
154	struct dns_query	*next;
155};
156
157struct dns_rr {
158	char			*name;
159	u_int16_t		type;
160	u_int16_t		class;
161	u_int16_t		ttl;
162	u_int16_t		size;
163	void			*rdata;
164	struct dns_rr		*next;
165};
166
167struct dns_response {
168	HEADER			header;
169	struct dns_query	*query;
170	struct dns_rr		*answer;
171	struct dns_rr		*authority;
172	struct dns_rr		*additional;
173};
174
175static struct dns_response *parse_dns_response(const u_char *, int);
176static struct dns_query *parse_dns_qsection(const u_char *, int,
177    const u_char **, int);
178static struct dns_rr *parse_dns_rrsection(const u_char *, int, const u_char **,
179    int);
180
181static void free_dns_query(struct dns_query *);
182static void free_dns_rr(struct dns_rr *);
183static void free_dns_response(struct dns_response *);
184
185static int count_dns_rr(struct dns_rr *, u_int16_t, u_int16_t);
186
187int
188getrrsetbyname(const char *hostname, unsigned int rdclass,
189    unsigned int rdtype, unsigned int flags,
190    struct rrsetinfo **res)
191{
192	struct __res_state *_resp;
193	int result;
194	unsigned long options;
195	struct rrsetinfo *rrset = NULL;
196	struct dns_response *response = NULL;
197	struct dns_rr *rr;
198	struct rdatainfo *rdata;
199	int length;
200	unsigned int index_ans, index_sig;
201	u_char answer[ANSWER_BUFFER_SIZE];
202
203	/* check for invalid class and type */
204	if (rdclass > 0xffff || rdtype > 0xffff) {
205		return ERRSET_INVAL;
206	}
207
208	/* don't allow queries of class or type ANY */
209	if (rdclass == 0xff || rdtype == 0xff) {
210		return ERRSET_INVAL;
211	}
212
213	/* don't allow flags yet, unimplemented */
214	if (flags) {
215		return ERRSET_INVAL;
216	}
217
218#ifndef __NetBSD__
219	_resp = _THREAD_PRIVATE(_res, _res, &_res);
220	/* initialize resolver */
221	if ((_resp->options & RES_INIT) == 0 && res_init() == -1) {
222		result = ERRSET_FAIL;
223		goto fail;
224	}
225#else
226	_resp = __res_get_state();
227	if (_resp == NULL) {
228		return ERRSET_FAIL;
229	}
230#endif
231	options = _resp->options;
232
233#ifdef DEBUG
234	_resp->options |= RES_DEBUG;
235#endif /* DEBUG */
236
237#ifdef RES_USE_DNSSEC
238	/* turn on DNSSEC if EDNS0 is configured */
239	if (_resp->options & RES_USE_EDNS0)
240		_resp->options |= RES_USE_DNSSEC;
241#endif /* RES_USE_DNSEC */
242
243	/* make query */
244	length = res_nquery(_resp, hostname, (signed int) rdclass,
245	    (signed int) rdtype, answer, sizeof(answer));
246	if (length < 0) {
247		switch(h_errno) {
248		case HOST_NOT_FOUND:
249			result = ERRSET_NONAME;
250			goto fail;
251		case NO_DATA:
252			result = ERRSET_NODATA;
253			goto fail;
254		default:
255			result = ERRSET_FAIL;
256			goto fail;
257		}
258	}
259
260	/* parse result */
261	response = parse_dns_response(answer, length);
262	if (response == NULL) {
263		result = ERRSET_FAIL;
264		goto fail;
265	}
266
267	if (response->header.qdcount != 1) {
268		result = ERRSET_FAIL;
269		goto fail;
270	}
271
272	/* initialize rrset */
273	rrset = calloc(1, sizeof(struct rrsetinfo));
274	if (rrset == NULL) {
275		result = ERRSET_NOMEMORY;
276		goto fail;
277	}
278	rrset->rri_rdclass = response->query->class;
279	rrset->rri_rdtype = response->query->type;
280	rrset->rri_ttl = response->answer->ttl;
281	rrset->rri_nrdatas = response->header.ancount;
282
283#ifdef HAVE_HEADER_AD
284	/* check for authenticated data */
285	if (response->header.ad == 1)
286		rrset->rri_flags |= RRSET_VALIDATED;
287#endif
288
289	/* copy name from answer section */
290	rrset->rri_name = strdup(response->answer->name);
291	if (rrset->rri_name == NULL) {
292		result = ERRSET_NOMEMORY;
293		goto fail;
294	}
295
296	/* count answers */
297	rrset->rri_nrdatas = count_dns_rr(response->answer, rrset->rri_rdclass,
298	    rrset->rri_rdtype);
299	rrset->rri_nsigs = count_dns_rr(response->answer, rrset->rri_rdclass,
300	    T_SIG);
301
302	/* allocate memory for answers */
303	rrset->rri_rdatas = calloc(rrset->rri_nrdatas,
304	    sizeof(struct rdatainfo));
305	if (rrset->rri_rdatas == NULL) {
306		result = ERRSET_NOMEMORY;
307		goto fail;
308	}
309
310	/* allocate memory for signatures */
311	rrset->rri_sigs = calloc(rrset->rri_nsigs, sizeof(struct rdatainfo));
312	if (rrset->rri_sigs == NULL) {
313		result = ERRSET_NOMEMORY;
314		goto fail;
315	}
316
317	/* copy answers & signatures */
318	for (rr = response->answer, index_ans = 0, index_sig = 0;
319	    rr; rr = rr->next) {
320
321		rdata = NULL;
322
323		if (rr->class == rrset->rri_rdclass &&
324		    rr->type  == rrset->rri_rdtype)
325			rdata = &rrset->rri_rdatas[index_ans++];
326
327		if (rr->class == rrset->rri_rdclass &&
328		    rr->type  == T_SIG)
329			rdata = &rrset->rri_sigs[index_sig++];
330
331		if (rdata) {
332			rdata->rdi_length = rr->size;
333			rdata->rdi_data   = malloc(rr->size);
334
335			if (rdata->rdi_data == NULL) {
336				result = ERRSET_NOMEMORY;
337				goto fail;
338			}
339			memcpy(rdata->rdi_data, rr->rdata, rr->size);
340		}
341	}
342	free_dns_response(response);
343
344	*res = rrset;
345	_resp->options = options;
346#ifdef __NetBSD__
347	__res_put_state(_resp);
348#endif
349	return (ERRSET_SUCCESS);
350
351fail:
352	_resp->options = options;
353#ifdef __NetBSD__
354	__res_put_state(_resp);
355#endif
356	if (rrset != NULL)
357		freerrset(rrset);
358	if (response != NULL)
359		free_dns_response(response);
360	return (result);
361}
362
363void
364freerrset(struct rrsetinfo *rrset)
365{
366	u_int16_t i;
367
368	if (rrset == NULL)
369		return;
370
371	if (rrset->rri_rdatas) {
372		for (i = 0; i < rrset->rri_nrdatas; i++) {
373			if (rrset->rri_rdatas[i].rdi_data == NULL)
374				break;
375			free(rrset->rri_rdatas[i].rdi_data);
376		}
377		free(rrset->rri_rdatas);
378	}
379
380	if (rrset->rri_sigs) {
381		for (i = 0; i < rrset->rri_nsigs; i++) {
382			if (rrset->rri_sigs[i].rdi_data == NULL)
383				break;
384			free(rrset->rri_sigs[i].rdi_data);
385		}
386		free(rrset->rri_sigs);
387	}
388
389	if (rrset->rri_name)
390		free(rrset->rri_name);
391	free(rrset);
392}
393
394/*
395 * DNS response parsing routines
396 */
397static struct dns_response *
398parse_dns_response(const u_char *answer, int size)
399{
400	struct dns_response *resp;
401	const u_char *cp;
402
403	/* allocate memory for the response */
404	resp = calloc(1, sizeof(*resp));
405	if (resp == NULL)
406		return (NULL);
407
408	/* initialize current pointer */
409	cp = answer;
410
411	/* copy header */
412	memcpy(&resp->header, cp, HFIXEDSZ);
413	cp += HFIXEDSZ;
414
415	/* fix header byte order */
416	resp->header.qdcount = ntohs(resp->header.qdcount);
417	resp->header.ancount = ntohs(resp->header.ancount);
418	resp->header.nscount = ntohs(resp->header.nscount);
419	resp->header.arcount = ntohs(resp->header.arcount);
420
421	/* there must be at least one query */
422	if (resp->header.qdcount < 1) {
423		free_dns_response(resp);
424		return (NULL);
425	}
426
427	/* parse query section */
428	resp->query = parse_dns_qsection(answer, size, &cp,
429	    resp->header.qdcount);
430	if (resp->header.qdcount && resp->query == NULL) {
431		free_dns_response(resp);
432		return (NULL);
433	}
434
435	/* parse answer section */
436	resp->answer = parse_dns_rrsection(answer, size, &cp,
437	    resp->header.ancount);
438	if (resp->header.ancount && resp->answer == NULL) {
439		free_dns_response(resp);
440		return (NULL);
441	}
442
443	/* parse authority section */
444	resp->authority = parse_dns_rrsection(answer, size, &cp,
445	    resp->header.nscount);
446	if (resp->header.nscount && resp->authority == NULL) {
447		free_dns_response(resp);
448		return (NULL);
449	}
450
451	/* parse additional section */
452	resp->additional = parse_dns_rrsection(answer, size, &cp,
453	    resp->header.arcount);
454	if (resp->header.arcount && resp->additional == NULL) {
455		free_dns_response(resp);
456		return (NULL);
457	}
458
459	return (resp);
460}
461
462static struct dns_query *
463parse_dns_qsection(const u_char *answer, int size, const u_char **cp, int count)
464{
465	struct dns_query *head, *curr, *prev;
466	int i, length;
467	char name[MAXDNAME];
468
469	for (i = 1, head = NULL, prev = NULL; i <= count; i++, prev = curr) {
470
471		/* allocate and initialize struct */
472		curr = calloc(1, sizeof(struct dns_query));
473		if (curr == NULL) {
474			free_dns_query(head);
475			return (NULL);
476		}
477		if (head == NULL)
478			head = curr;
479		if (prev != NULL)
480			prev->next = curr;
481
482		/* name */
483		length = dn_expand(answer, answer + size, *cp, name,
484		    (int)sizeof(name));
485		if (length < 0) {
486			free_dns_query(head);
487			return (NULL);
488		}
489		curr->name = strdup(name);
490		if (curr->name == NULL) {
491			free_dns_query(head);
492			return (NULL);
493		}
494		*cp += length;
495
496		/* type */
497		curr->type = _getshort(*cp);
498		*cp += INT16SZ;
499
500		/* class */
501		curr->class = _getshort(*cp);
502		*cp += INT16SZ;
503	}
504
505	return (head);
506}
507
508static struct dns_rr *
509parse_dns_rrsection(const u_char *answer, int size, const u_char **cp,
510    int count)
511{
512	struct dns_rr *head, *curr, *prev;
513	int i, length;
514	char name[MAXDNAME];
515
516	for (i = 1, head = NULL, prev = NULL; i <= count; i++, prev = curr) {
517
518		/* allocate and initialize struct */
519		curr = calloc(1, sizeof(struct dns_rr));
520		if (curr == NULL) {
521			free_dns_rr(head);
522			return (NULL);
523		}
524		if (head == NULL)
525			head = curr;
526		if (prev != NULL)
527			prev->next = curr;
528
529		/* name */
530		length = dn_expand(answer, answer + size, *cp, name,
531		    (int)sizeof(name));
532		if (length < 0) {
533			free_dns_rr(head);
534			return (NULL);
535		}
536		curr->name = strdup(name);
537		if (curr->name == NULL) {
538			free_dns_rr(head);
539			return (NULL);
540		}
541		*cp += length;
542
543		/* type */
544		curr->type = _getshort(*cp);
545		*cp += INT16SZ;
546
547		/* class */
548		curr->class = _getshort(*cp);
549		*cp += INT16SZ;
550
551		/* ttl */
552		curr->ttl = _getlong(*cp);
553		*cp += INT32SZ;
554
555		/* rdata size */
556		curr->size = _getshort(*cp);
557		*cp += INT16SZ;
558
559		/* rdata itself */
560		curr->rdata = malloc(curr->size);
561		if (curr->rdata == NULL) {
562			free_dns_rr(head);
563			return (NULL);
564		}
565		memcpy(curr->rdata, *cp, curr->size);
566		*cp += curr->size;
567	}
568
569	return (head);
570}
571
572static void
573free_dns_query(struct dns_query *p)
574{
575	if (p == NULL)
576		return;
577
578	if (p->name)
579		free(p->name);
580	free_dns_query(p->next);
581	free(p);
582}
583
584static void
585free_dns_rr(struct dns_rr *p)
586{
587	if (p == NULL)
588		return;
589
590	if (p->name)
591		free(p->name);
592	if (p->rdata)
593		free(p->rdata);
594	free_dns_rr(p->next);
595	free(p);
596}
597
598static void
599free_dns_response(struct dns_response *p)
600{
601	if (p == NULL)
602		return;
603
604	free_dns_query(p->query);
605	free_dns_rr(p->answer);
606	free_dns_rr(p->authority);
607	free_dns_rr(p->additional);
608	free(p);
609}
610
611static int
612count_dns_rr(struct dns_rr *p, u_int16_t class, u_int16_t type)
613{
614	int n = 0;
615
616	while(p) {
617		if (p->class == class && p->type == type)
618			n++;
619		p = p->next;
620	}
621
622	return (n);
623}
624
625#endif /* !defined(HAVE_GETRRSETBYNAME) */
626