xref: /freebsd/crypto/heimdal/lib/roken/resolve.c (revision 1e413cf93298b5b97441a21d9a50fdcd0ee9945e)
1 /*
2  * Copyright (c) 1995 - 2003 Kungliga Tekniska H�gskolan
3  * (Royal Institute of Technology, Stockholm, Sweden).
4  * 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  * 3. Neither the name of the Institute nor the names of its contributors
18  *    may be used to endorse or promote products derived from this software
19  *    without specific prior written permission.
20  *
21  * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31  * SUCH DAMAGE.
32  */
33 
34 #ifdef HAVE_CONFIG_H
35 #include <config.h>
36 #endif
37 #include "roken.h"
38 #ifdef HAVE_ARPA_NAMESER_H
39 #include <arpa/nameser.h>
40 #endif
41 #ifdef HAVE_RESOLV_H
42 #include <resolv.h>
43 #endif
44 #include "resolve.h"
45 
46 #include <assert.h>
47 
48 RCSID("$Id: resolve.c,v 1.38.2.1 2003/04/22 15:02:47 lha Exp $");
49 
50 #undef HAVE_RES_NSEARCH
51 #if (defined(HAVE_RES_SEARCH) || defined(HAVE_RES_NSEARCH)) && defined(HAVE_DN_EXPAND)
52 
53 #define DECL(X) {#X, T_##X}
54 
55 static struct stot{
56     const char *name;
57     int type;
58 }stot[] = {
59     DECL(A),
60     DECL(NS),
61     DECL(CNAME),
62     DECL(SOA),
63     DECL(PTR),
64     DECL(MX),
65     DECL(TXT),
66     DECL(AFSDB),
67     DECL(SIG),
68     DECL(KEY),
69     DECL(SRV),
70     DECL(NAPTR),
71     {NULL, 	0}
72 };
73 
74 int _resolve_debug = 0;
75 
76 int
77 dns_string_to_type(const char *name)
78 {
79     struct stot *p = stot;
80     for(p = stot; p->name; p++)
81 	if(strcasecmp(name, p->name) == 0)
82 	    return p->type;
83     return -1;
84 }
85 
86 const char *
87 dns_type_to_string(int type)
88 {
89     struct stot *p = stot;
90     for(p = stot; p->name; p++)
91 	if(type == p->type)
92 	    return p->name;
93     return NULL;
94 }
95 
96 void
97 dns_free_data(struct dns_reply *r)
98 {
99     struct resource_record *rr;
100     if(r->q.domain)
101 	free(r->q.domain);
102     for(rr = r->head; rr;){
103 	struct resource_record *tmp = rr;
104 	if(rr->domain)
105 	    free(rr->domain);
106 	if(rr->u.data)
107 	    free(rr->u.data);
108 	rr = rr->next;
109 	free(tmp);
110     }
111     free (r);
112 }
113 
114 static int
115 parse_record(const unsigned char *data, const unsigned char *end_data,
116 	     const unsigned char **pp, struct resource_record **rr)
117 {
118     int type, class, ttl, size;
119     int status;
120     char host[MAXDNAME];
121     const unsigned char *p = *pp;
122     status = dn_expand(data, end_data, p, host, sizeof(host));
123     if(status < 0)
124 	return -1;
125     if (p + status + 10 > end_data)
126 	return -1;
127     p += status;
128     type = (p[0] << 8) | p[1];
129     p += 2;
130     class = (p[0] << 8) | p[1];
131     p += 2;
132     ttl = (p[0] << 24) | (p[1] << 16) | (p[2] << 8) | p[3];
133     p += 4;
134     size = (p[0] << 8) | p[1];
135     p += 2;
136 
137     if (p + size > end_data)
138 	return -1;
139 
140     *rr = calloc(1, sizeof(**rr));
141     if(*rr == NULL)
142 	return -1;
143     (*rr)->domain = strdup(host);
144     if((*rr)->domain == NULL) {
145 	free(*rr);
146 	return -1;
147     }
148     (*rr)->type = type;
149     (*rr)->class = class;
150     (*rr)->ttl = ttl;
151     (*rr)->size = size;
152     switch(type){
153     case T_NS:
154     case T_CNAME:
155     case T_PTR:
156 	status = dn_expand(data, end_data, p, host, sizeof(host));
157 	if(status < 0) {
158 	    free(*rr);
159 	    return -1;
160 	}
161 	(*rr)->u.txt = strdup(host);
162 	if((*rr)->u.txt == NULL) {
163 	    free(*rr);
164 	    return -1;
165 	}
166 	break;
167     case T_MX:
168     case T_AFSDB:{
169 	size_t hostlen;
170 
171 	status = dn_expand(data, end_data, p + 2, host, sizeof(host));
172 	if(status < 0){
173 	    free(*rr);
174 	    return -1;
175 	}
176 	if (status + 2 > size) {
177 	    free(*rr);
178 	    return -1;
179 	}
180 
181 	hostlen = strlen(host);
182 	(*rr)->u.mx = (struct mx_record*)malloc(sizeof(struct mx_record) +
183 						hostlen);
184 	if((*rr)->u.mx == NULL) {
185 	    free(*rr);
186 	    return -1;
187 	}
188 	(*rr)->u.mx->preference = (p[0] << 8) | p[1];
189 	strlcpy((*rr)->u.mx->domain, host, hostlen + 1);
190 	break;
191     }
192     case T_SRV:{
193 	size_t hostlen;
194 	status = dn_expand(data, end_data, p + 6, host, sizeof(host));
195 	if(status < 0){
196 	    free(*rr);
197 	    return -1;
198 	}
199 	if (status + 6 > size) {
200 	    free(*rr);
201 	    return -1;
202 	}
203 
204 	hostlen = strlen(host);
205 	(*rr)->u.srv =
206 	    (struct srv_record*)malloc(sizeof(struct srv_record) +
207 				       hostlen);
208 	if((*rr)->u.srv == NULL) {
209 	    free(*rr);
210 	    return -1;
211 	}
212 	(*rr)->u.srv->priority = (p[0] << 8) | p[1];
213 	(*rr)->u.srv->weight = (p[2] << 8) | p[3];
214 	(*rr)->u.srv->port = (p[4] << 8) | p[5];
215 	strlcpy((*rr)->u.srv->target, host, hostlen + 1);
216 	break;
217     }
218     case T_TXT:{
219 	if(size == 0 || size < *p + 1) {
220 	    free(*rr);
221 	    return -1;
222 	}
223 	(*rr)->u.txt = (char*)malloc(*p + 1);
224 	if((*rr)->u.txt == NULL) {
225 	    free(*rr);
226 	    return -1;
227 	}
228 	strncpy((*rr)->u.txt, (char*)p + 1, *p);
229 	(*rr)->u.txt[*p] = '\0';
230 	break;
231     }
232     case T_KEY : {
233 	size_t key_len;
234 
235 	if (size < 4) {
236 	    free(*rr);
237 	    return -1;
238 	}
239 
240 	key_len = size - 4;
241 	(*rr)->u.key = malloc (sizeof(*(*rr)->u.key) + key_len - 1);
242 	if ((*rr)->u.key == NULL) {
243 	    free(*rr);
244 	    return -1;
245 	}
246 
247 	(*rr)->u.key->flags     = (p[0] << 8) | p[1];
248 	(*rr)->u.key->protocol  = p[2];
249 	(*rr)->u.key->algorithm = p[3];
250 	(*rr)->u.key->key_len   = key_len;
251 	memcpy ((*rr)->u.key->key_data, p + 4, key_len);
252 	break;
253     }
254     case T_SIG : {
255 	size_t sig_len, hostlen;
256 
257 	if(size <= 18) {
258 	    free(*rr);
259 	    return -1;
260 	}
261 	status = dn_expand (data, end_data, p + 18, host, sizeof(host));
262 	if (status < 0) {
263 	    free(*rr);
264 	    return -1;
265 	}
266 	if (status + 18 > size) {
267 	    free(*rr);
268 	    return -1;
269 	}
270 
271 	/* the signer name is placed after the sig_data, to make it
272            easy to free this struture; the size calculation below
273            includes the zero-termination if the structure itself.
274 	   don't you just love C?
275 	*/
276 	sig_len = size - 18 - status;
277 	hostlen = strlen(host);
278 	(*rr)->u.sig = malloc(sizeof(*(*rr)->u.sig)
279 			      + hostlen + sig_len);
280 	if ((*rr)->u.sig == NULL) {
281 	    free(*rr);
282 	    return -1;
283 	}
284 	(*rr)->u.sig->type           = (p[0] << 8) | p[1];
285 	(*rr)->u.sig->algorithm      = p[2];
286 	(*rr)->u.sig->labels         = p[3];
287 	(*rr)->u.sig->orig_ttl       = (p[4] << 24) | (p[5] << 16)
288 	    | (p[6] << 8) | p[7];
289 	(*rr)->u.sig->sig_expiration = (p[8] << 24) | (p[9] << 16)
290 	    | (p[10] << 8) | p[11];
291 	(*rr)->u.sig->sig_inception  = (p[12] << 24) | (p[13] << 16)
292 	    | (p[14] << 8) | p[15];
293 	(*rr)->u.sig->key_tag        = (p[16] << 8) | p[17];
294 	(*rr)->u.sig->sig_len        = sig_len;
295 	memcpy ((*rr)->u.sig->sig_data, p + 18 + status, sig_len);
296 	(*rr)->u.sig->signer         = &(*rr)->u.sig->sig_data[sig_len];
297 	strlcpy((*rr)->u.sig->signer, host, hostlen + 1);
298 	break;
299     }
300 
301     case T_CERT : {
302 	size_t cert_len;
303 
304 	if (size < 5) {
305 	    free(*rr);
306 	    return -1;
307 	}
308 
309 	cert_len = size - 5;
310 	(*rr)->u.cert = malloc (sizeof(*(*rr)->u.cert) + cert_len - 1);
311 	if ((*rr)->u.cert == NULL) {
312 	    free(*rr);
313 	    return -1;
314 	}
315 
316 	(*rr)->u.cert->type      = (p[0] << 8) | p[1];
317 	(*rr)->u.cert->tag       = (p[2] << 8) | p[3];
318 	(*rr)->u.cert->algorithm = p[4];
319 	(*rr)->u.cert->cert_len  = cert_len;
320 	memcpy ((*rr)->u.cert->cert_data, p + 5, cert_len);
321 	break;
322     }
323     default:
324 	(*rr)->u.data = (unsigned char*)malloc(size);
325 	if(size != 0 && (*rr)->u.data == NULL) {
326 	    free(*rr);
327 	    return -1;
328 	}
329 	memcpy((*rr)->u.data, p, size);
330     }
331     *pp = p + size;
332     return 0;
333 }
334 
335 #ifndef TEST_RESOLVE
336 static
337 #endif
338 struct dns_reply*
339 parse_reply(const unsigned char *data, size_t len)
340 {
341     const unsigned char *p;
342     int status;
343     int i;
344     char host[MAXDNAME];
345     const unsigned char *end_data = data + len;
346     struct dns_reply *r;
347     struct resource_record **rr;
348 
349     r = calloc(1, sizeof(*r));
350     if (r == NULL)
351 	return NULL;
352 
353     p = data;
354 #if 0
355     /* doesn't work on Crays */
356     memcpy(&r->h, p, sizeof(HEADER));
357     p += sizeof(HEADER);
358 #else
359     memcpy(&r->h, p, 12); /* XXX this will probably be mostly garbage */
360     p += 12;
361 #endif
362     if(ntohs(r->h.qdcount) != 1) {
363 	free(r);
364 	return NULL;
365     }
366     status = dn_expand(data, end_data, p, host, sizeof(host));
367     if(status < 0){
368 	dns_free_data(r);
369 	return NULL;
370     }
371     r->q.domain = strdup(host);
372     if(r->q.domain == NULL) {
373 	dns_free_data(r);
374 	return NULL;
375     }
376     if (p + status + 4 > end_data) {
377 	dns_free_data(r);
378 	return NULL;
379     }
380     p += status;
381     r->q.type = (p[0] << 8 | p[1]);
382     p += 2;
383     r->q.class = (p[0] << 8 | p[1]);
384     p += 2;
385 
386     rr = &r->head;
387     for(i = 0; i < ntohs(r->h.ancount); i++) {
388 	if(parse_record(data, end_data, &p, rr) != 0) {
389 	    dns_free_data(r);
390 	    return NULL;
391 	}
392 	rr = &(*rr)->next;
393     }
394     for(i = 0; i < ntohs(r->h.nscount); i++) {
395 	if(parse_record(data, end_data, &p, rr) != 0) {
396 	    dns_free_data(r);
397 	    return NULL;
398 	}
399 	rr = &(*rr)->next;
400     }
401     for(i = 0; i < ntohs(r->h.arcount); i++) {
402 	if(parse_record(data, end_data, &p, rr) != 0) {
403 	    dns_free_data(r);
404 	    return NULL;
405 	}
406 	rr = &(*rr)->next;
407     }
408     *rr = NULL;
409     return r;
410 }
411 
412 static struct dns_reply *
413 dns_lookup_int(const char *domain, int rr_class, int rr_type)
414 {
415     unsigned char reply[1024];
416     int len;
417 #ifdef HAVE_RES_NSEARCH
418     struct __res_state stat;
419     memset(&stat, 0, sizeof(stat));
420     if(res_ninit(&stat))
421 	return NULL; /* is this the best we can do? */
422 #elif defined(HAVE__RES)
423     u_long old_options = 0;
424 #endif
425 
426     if (_resolve_debug) {
427 #ifdef HAVE_RES_NSEARCH
428 	stat.options |= RES_DEBUG;
429 #elif defined(HAVE__RES)
430         old_options = _res.options;
431 	_res.options |= RES_DEBUG;
432 #endif
433 	fprintf(stderr, "dns_lookup(%s, %d, %s)\n", domain,
434 		rr_class, dns_type_to_string(rr_type));
435     }
436 #ifdef HAVE_RES_NSEARCH
437     len = res_nsearch(&stat, domain, rr_class, rr_type, reply, sizeof(reply));
438 #else
439     len = res_search(domain, rr_class, rr_type, reply, sizeof(reply));
440 #endif
441     if (_resolve_debug) {
442 #if defined(HAVE__RES) && !defined(HAVE_RES_NSEARCH)
443         _res.options = old_options;
444 #endif
445 	fprintf(stderr, "dns_lookup(%s, %d, %s) --> %d\n",
446 		domain, rr_class, dns_type_to_string(rr_type), len);
447     }
448 #ifdef HAVE_RES_NSEARCH
449     res_nclose(&stat);
450 #endif
451     if(len < 0) {
452 	return NULL;
453     } else {
454 	len = min(len, sizeof(reply));
455 	return parse_reply(reply, len);
456     }
457 }
458 
459 struct dns_reply *
460 dns_lookup(const char *domain, const char *type_name)
461 {
462     int type;
463 
464     type = dns_string_to_type(type_name);
465     if(type == -1) {
466 	if(_resolve_debug)
467 	    fprintf(stderr, "dns_lookup: unknown resource type: `%s'\n",
468 		    type_name);
469 	return NULL;
470     }
471     return dns_lookup_int(domain, C_IN, type);
472 }
473 
474 static int
475 compare_srv(const void *a, const void *b)
476 {
477     const struct resource_record *const* aa = a, *const* bb = b;
478 
479     if((*aa)->u.srv->priority == (*bb)->u.srv->priority)
480 	return ((*aa)->u.srv->weight - (*bb)->u.srv->weight);
481     return ((*aa)->u.srv->priority - (*bb)->u.srv->priority);
482 }
483 
484 #ifndef HAVE_RANDOM
485 #define random() rand()
486 #endif
487 
488 /* try to rearrange the srv-records by the algorithm in RFC2782 */
489 void
490 dns_srv_order(struct dns_reply *r)
491 {
492     struct resource_record **srvs, **ss, **headp;
493     struct resource_record *rr;
494     int num_srv = 0;
495 
496 #if defined(HAVE_INITSTATE) && defined(HAVE_SETSTATE)
497     int state[256 / sizeof(int)];
498     char *oldstate;
499 #endif
500 
501     for(rr = r->head; rr; rr = rr->next)
502 	if(rr->type == T_SRV)
503 	    num_srv++;
504 
505     if(num_srv == 0)
506 	return;
507 
508     srvs = malloc(num_srv * sizeof(*srvs));
509     if(srvs == NULL)
510 	return; /* XXX not much to do here */
511 
512     /* unlink all srv-records from the linked list and put them in
513        a vector */
514     for(ss = srvs, headp = &r->head; *headp; )
515 	if((*headp)->type == T_SRV) {
516 	    *ss = *headp;
517 	    *headp = (*headp)->next;
518 	    (*ss)->next = NULL;
519 	    ss++;
520 	} else
521 	    headp = &(*headp)->next;
522 
523     /* sort them by priority and weight */
524     qsort(srvs, num_srv, sizeof(*srvs), compare_srv);
525 
526 #if defined(HAVE_INITSTATE) && defined(HAVE_SETSTATE)
527     oldstate = initstate(time(NULL), (char*)state, sizeof(state));
528 #endif
529 
530     headp = &r->head;
531 
532     for(ss = srvs; ss < srvs + num_srv; ) {
533 	int sum, rnd, count;
534 	struct resource_record **ee, **tt;
535 	/* find the last record with the same priority and count the
536            sum of all weights */
537 	for(sum = 0, tt = ss; tt < srvs + num_srv; tt++) {
538 	    if(*tt == NULL)
539 		continue;
540 	    if((*tt)->u.srv->priority != (*ss)->u.srv->priority)
541 		break;
542 	    sum += (*tt)->u.srv->weight;
543 	}
544 	ee = tt;
545 	/* ss is now the first record of this priority and ee is the
546            first of the next */
547 	while(ss < ee) {
548 	    rnd = random() % (sum + 1);
549 	    for(count = 0, tt = ss; ; tt++) {
550 		if(*tt == NULL)
551 		    continue;
552 		count += (*tt)->u.srv->weight;
553 		if(count >= rnd)
554 		    break;
555 	    }
556 
557 	    assert(tt < ee);
558 
559 	    /* insert the selected record at the tail (of the head) of
560                the list */
561 	    (*tt)->next = *headp;
562 	    *headp = *tt;
563 	    headp = &(*tt)->next;
564 	    sum -= (*tt)->u.srv->weight;
565 	    *tt = NULL;
566 	    while(ss < ee && *ss == NULL)
567 		ss++;
568 	}
569     }
570 
571 #if defined(HAVE_INITSTATE) && defined(HAVE_SETSTATE)
572     setstate(oldstate);
573 #endif
574     free(srvs);
575     return;
576 }
577 
578 #else /* NOT defined(HAVE_RES_SEARCH) && defined(HAVE_DN_EXPAND) */
579 
580 struct dns_reply *
581 dns_lookup(const char *domain, const char *type_name)
582 {
583     return NULL;
584 }
585 
586 void
587 dns_free_data(struct dns_reply *r)
588 {
589 }
590 
591 void
592 dns_srv_order(struct dns_reply *r)
593 {
594 }
595 
596 #endif
597 
598 #ifdef TEST
599 int
600 main(int argc, char **argv)
601 {
602     struct dns_reply *r;
603     struct resource_record *rr;
604     r = dns_lookup(argv[1], argv[2]);
605     if(r == NULL){
606 	printf("No reply.\n");
607 	return 1;
608     }
609     if(r->q.type == T_SRV)
610 	dns_srv_order(r);
611 
612     for(rr = r->head; rr;rr=rr->next){
613 	printf("%-30s %-5s %-6d ", rr->domain, dns_type_to_string(rr->type), rr->ttl);
614 	switch(rr->type){
615 	case T_NS:
616 	case T_CNAME:
617 	case T_PTR:
618 	    printf("%s\n", (char*)rr->u.data);
619 	    break;
620 	case T_A:
621 	    printf("%s\n", inet_ntoa(*rr->u.a));
622 	    break;
623 	case T_MX:
624 	case T_AFSDB:{
625 	    printf("%d %s\n", rr->u.mx->preference, rr->u.mx->domain);
626 	    break;
627 	}
628 	case T_SRV:{
629 	    struct srv_record *srv = rr->u.srv;
630 	    printf("%d %d %d %s\n", srv->priority, srv->weight,
631 		   srv->port, srv->target);
632 	    break;
633 	}
634 	case T_TXT: {
635 	    printf("%s\n", rr->u.txt);
636 	    break;
637 	}
638 	case T_SIG : {
639 	    struct sig_record *sig = rr->u.sig;
640 	    const char *type_string = dns_type_to_string (sig->type);
641 
642 	    printf ("type %u (%s), algorithm %u, labels %u, orig_ttl %u, sig_expiration %u, sig_inception %u, key_tag %u, signer %s\n",
643 		    sig->type, type_string ? type_string : "",
644 		    sig->algorithm, sig->labels, sig->orig_ttl,
645 		    sig->sig_expiration, sig->sig_inception, sig->key_tag,
646 		    sig->signer);
647 	    break;
648 	}
649 	case T_KEY : {
650 	    struct key_record *key = rr->u.key;
651 
652 	    printf ("flags %u, protocol %u, algorithm %u\n",
653 		    key->flags, key->protocol, key->algorithm);
654 	    break;
655 	}
656 	default:
657 	    printf("\n");
658 	    break;
659 	}
660     }
661 
662     return 0;
663 }
664 #endif
665