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 61 extern 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 71 struct __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 #define _getshort(x) (_ssh_compat_getshort(x)) 120 #define _getlong(x) (_ssh_compat_getlong(x)) 121 /* 122 * Routines to insert/extract short/long's. 123 */ 124 static u_int16_t 125 _getshort(const u_char *msgp) 126 { 127 u_int16_t u; 128 129 GETSHORT(u, msgp); 130 return (u); 131 } 132 133 static u_int32_t 134 _getlong(const u_char *msgp) 135 { 136 u_int32_t u; 137 138 GETLONG(u, msgp); 139 return (u); 140 } 141 #endif 142 143 /* ************** */ 144 145 #define ANSWER_BUFFER_SIZE 0xffff 146 147 struct dns_query { 148 char *name; 149 u_int16_t type; 150 u_int16_t class; 151 struct dns_query *next; 152 }; 153 154 struct dns_rr { 155 char *name; 156 u_int16_t type; 157 u_int16_t class; 158 u_int16_t ttl; 159 u_int16_t size; 160 void *rdata; 161 struct dns_rr *next; 162 }; 163 164 struct dns_response { 165 HEADER header; 166 struct dns_query *query; 167 struct dns_rr *answer; 168 struct dns_rr *authority; 169 struct dns_rr *additional; 170 }; 171 172 static struct dns_response *parse_dns_response(const u_char *, int); 173 static struct dns_query *parse_dns_qsection(const u_char *, int, 174 const u_char **, int); 175 static struct dns_rr *parse_dns_rrsection(const u_char *, int, const u_char **, 176 int); 177 178 static void free_dns_query(struct dns_query *); 179 static void free_dns_rr(struct dns_rr *); 180 static void free_dns_response(struct dns_response *); 181 182 static int count_dns_rr(struct dns_rr *, u_int16_t, u_int16_t); 183 184 int 185 getrrsetbyname(const char *hostname, unsigned int rdclass, 186 unsigned int rdtype, unsigned int flags, 187 struct rrsetinfo **res) 188 { 189 struct __res_state *_resp = _THREAD_PRIVATE(_res, _res, &_res); 190 int result; 191 struct rrsetinfo *rrset = NULL; 192 struct dns_response *response = NULL; 193 struct dns_rr *rr; 194 struct rdatainfo *rdata; 195 int length; 196 unsigned int index_ans, index_sig; 197 u_char answer[ANSWER_BUFFER_SIZE]; 198 199 /* check for invalid class and type */ 200 if (rdclass > 0xffff || rdtype > 0xffff) { 201 result = ERRSET_INVAL; 202 goto fail; 203 } 204 205 /* don't allow queries of class or type ANY */ 206 if (rdclass == 0xff || rdtype == 0xff) { 207 result = ERRSET_INVAL; 208 goto fail; 209 } 210 211 /* don't allow flags yet, unimplemented */ 212 if (flags) { 213 result = ERRSET_INVAL; 214 goto fail; 215 } 216 217 /* initialize resolver */ 218 if ((_resp->options & RES_INIT) == 0 && res_init() == -1) { 219 result = ERRSET_FAIL; 220 goto fail; 221 } 222 223 #ifdef DEBUG 224 _resp->options |= RES_DEBUG; 225 #endif /* DEBUG */ 226 227 #ifdef RES_USE_DNSSEC 228 /* turn on DNSSEC if EDNS0 is configured */ 229 if (_resp->options & RES_USE_EDNS0) 230 _resp->options |= RES_USE_DNSSEC; 231 #endif /* RES_USE_DNSEC */ 232 233 /* make query */ 234 length = res_query(hostname, (signed int) rdclass, (signed int) rdtype, 235 answer, sizeof(answer)); 236 if (length < 0) { 237 switch(h_errno) { 238 case HOST_NOT_FOUND: 239 result = ERRSET_NONAME; 240 goto fail; 241 case NO_DATA: 242 result = ERRSET_NODATA; 243 goto fail; 244 default: 245 result = ERRSET_FAIL; 246 goto fail; 247 } 248 } 249 250 /* parse result */ 251 response = parse_dns_response(answer, length); 252 if (response == NULL) { 253 result = ERRSET_FAIL; 254 goto fail; 255 } 256 257 if (response->header.qdcount != 1) { 258 result = ERRSET_FAIL; 259 goto fail; 260 } 261 262 /* initialize rrset */ 263 rrset = calloc(1, sizeof(struct rrsetinfo)); 264 if (rrset == NULL) { 265 result = ERRSET_NOMEMORY; 266 goto fail; 267 } 268 rrset->rri_rdclass = response->query->class; 269 rrset->rri_rdtype = response->query->type; 270 rrset->rri_ttl = response->answer->ttl; 271 rrset->rri_nrdatas = response->header.ancount; 272 273 #ifdef HAVE_HEADER_AD 274 /* check for authenticated data */ 275 if (response->header.ad == 1) 276 rrset->rri_flags |= RRSET_VALIDATED; 277 #endif 278 279 /* copy name from answer section */ 280 rrset->rri_name = strdup(response->answer->name); 281 if (rrset->rri_name == NULL) { 282 result = ERRSET_NOMEMORY; 283 goto fail; 284 } 285 286 /* count answers */ 287 rrset->rri_nrdatas = count_dns_rr(response->answer, rrset->rri_rdclass, 288 rrset->rri_rdtype); 289 rrset->rri_nsigs = count_dns_rr(response->answer, rrset->rri_rdclass, 290 T_RRSIG); 291 292 /* allocate memory for answers */ 293 rrset->rri_rdatas = calloc(rrset->rri_nrdatas, 294 sizeof(struct rdatainfo)); 295 if (rrset->rri_rdatas == NULL) { 296 result = ERRSET_NOMEMORY; 297 goto fail; 298 } 299 300 /* allocate memory for signatures */ 301 if (rrset->rri_nsigs > 0) { 302 rrset->rri_sigs = calloc(rrset->rri_nsigs, sizeof(struct rdatainfo)); 303 if (rrset->rri_sigs == NULL) { 304 result = ERRSET_NOMEMORY; 305 goto fail; 306 } 307 } 308 309 /* copy answers & signatures */ 310 for (rr = response->answer, index_ans = 0, index_sig = 0; 311 rr; rr = rr->next) { 312 313 rdata = NULL; 314 315 if (rr->class == rrset->rri_rdclass && 316 rr->type == rrset->rri_rdtype) 317 rdata = &rrset->rri_rdatas[index_ans++]; 318 319 if (rr->class == rrset->rri_rdclass && 320 rr->type == T_RRSIG) 321 rdata = &rrset->rri_sigs[index_sig++]; 322 323 if (rdata) { 324 rdata->rdi_length = rr->size; 325 rdata->rdi_data = malloc(rr->size); 326 327 if (rdata->rdi_data == NULL) { 328 result = ERRSET_NOMEMORY; 329 goto fail; 330 } 331 memcpy(rdata->rdi_data, rr->rdata, rr->size); 332 } 333 } 334 free_dns_response(response); 335 336 *res = rrset; 337 return (ERRSET_SUCCESS); 338 339 fail: 340 if (rrset != NULL) 341 freerrset(rrset); 342 if (response != NULL) 343 free_dns_response(response); 344 return (result); 345 } 346 347 void 348 freerrset(struct rrsetinfo *rrset) 349 { 350 u_int16_t i; 351 352 if (rrset == NULL) 353 return; 354 355 if (rrset->rri_rdatas) { 356 for (i = 0; i < rrset->rri_nrdatas; i++) { 357 if (rrset->rri_rdatas[i].rdi_data == NULL) 358 break; 359 free(rrset->rri_rdatas[i].rdi_data); 360 } 361 free(rrset->rri_rdatas); 362 } 363 364 if (rrset->rri_sigs) { 365 for (i = 0; i < rrset->rri_nsigs; i++) { 366 if (rrset->rri_sigs[i].rdi_data == NULL) 367 break; 368 free(rrset->rri_sigs[i].rdi_data); 369 } 370 free(rrset->rri_sigs); 371 } 372 373 if (rrset->rri_name) 374 free(rrset->rri_name); 375 free(rrset); 376 } 377 378 /* 379 * DNS response parsing routines 380 */ 381 static struct dns_response * 382 parse_dns_response(const u_char *answer, int size) 383 { 384 struct dns_response *resp; 385 const u_char *cp; 386 387 /* allocate memory for the response */ 388 resp = calloc(1, sizeof(*resp)); 389 if (resp == NULL) 390 return (NULL); 391 392 /* initialize current pointer */ 393 cp = answer; 394 395 /* copy header */ 396 memcpy(&resp->header, cp, HFIXEDSZ); 397 cp += HFIXEDSZ; 398 399 /* fix header byte order */ 400 resp->header.qdcount = ntohs(resp->header.qdcount); 401 resp->header.ancount = ntohs(resp->header.ancount); 402 resp->header.nscount = ntohs(resp->header.nscount); 403 resp->header.arcount = ntohs(resp->header.arcount); 404 405 /* there must be at least one query */ 406 if (resp->header.qdcount < 1) { 407 free_dns_response(resp); 408 return (NULL); 409 } 410 411 /* parse query section */ 412 resp->query = parse_dns_qsection(answer, size, &cp, 413 resp->header.qdcount); 414 if (resp->header.qdcount && resp->query == NULL) { 415 free_dns_response(resp); 416 return (NULL); 417 } 418 419 /* parse answer section */ 420 resp->answer = parse_dns_rrsection(answer, size, &cp, 421 resp->header.ancount); 422 if (resp->header.ancount && resp->answer == NULL) { 423 free_dns_response(resp); 424 return (NULL); 425 } 426 427 /* parse authority section */ 428 resp->authority = parse_dns_rrsection(answer, size, &cp, 429 resp->header.nscount); 430 if (resp->header.nscount && resp->authority == NULL) { 431 free_dns_response(resp); 432 return (NULL); 433 } 434 435 /* parse additional section */ 436 resp->additional = parse_dns_rrsection(answer, size, &cp, 437 resp->header.arcount); 438 if (resp->header.arcount && resp->additional == NULL) { 439 free_dns_response(resp); 440 return (NULL); 441 } 442 443 return (resp); 444 } 445 446 static struct dns_query * 447 parse_dns_qsection(const u_char *answer, int size, const u_char **cp, int count) 448 { 449 struct dns_query *head, *curr, *prev; 450 int i, length; 451 char name[MAXDNAME]; 452 453 for (i = 1, head = NULL, prev = NULL; i <= count; i++, prev = curr) { 454 455 /* allocate and initialize struct */ 456 curr = calloc(1, sizeof(struct dns_query)); 457 if (curr == NULL) { 458 free_dns_query(head); 459 return (NULL); 460 } 461 if (head == NULL) 462 head = curr; 463 if (prev != NULL) 464 prev->next = curr; 465 466 /* name */ 467 length = dn_expand(answer, answer + size, *cp, name, 468 sizeof(name)); 469 if (length < 0) { 470 free_dns_query(head); 471 return (NULL); 472 } 473 curr->name = strdup(name); 474 if (curr->name == NULL) { 475 free_dns_query(head); 476 return (NULL); 477 } 478 *cp += length; 479 480 /* type */ 481 curr->type = _getshort(*cp); 482 *cp += INT16SZ; 483 484 /* class */ 485 curr->class = _getshort(*cp); 486 *cp += INT16SZ; 487 } 488 489 return (head); 490 } 491 492 static struct dns_rr * 493 parse_dns_rrsection(const u_char *answer, int size, const u_char **cp, 494 int count) 495 { 496 struct dns_rr *head, *curr, *prev; 497 int i, length; 498 char name[MAXDNAME]; 499 500 for (i = 1, head = NULL, prev = NULL; i <= count; i++, prev = curr) { 501 502 /* allocate and initialize struct */ 503 curr = calloc(1, sizeof(struct dns_rr)); 504 if (curr == NULL) { 505 free_dns_rr(head); 506 return (NULL); 507 } 508 if (head == NULL) 509 head = curr; 510 if (prev != NULL) 511 prev->next = curr; 512 513 /* name */ 514 length = dn_expand(answer, answer + size, *cp, name, 515 sizeof(name)); 516 if (length < 0) { 517 free_dns_rr(head); 518 return (NULL); 519 } 520 curr->name = strdup(name); 521 if (curr->name == NULL) { 522 free_dns_rr(head); 523 return (NULL); 524 } 525 *cp += length; 526 527 /* type */ 528 curr->type = _getshort(*cp); 529 *cp += INT16SZ; 530 531 /* class */ 532 curr->class = _getshort(*cp); 533 *cp += INT16SZ; 534 535 /* ttl */ 536 curr->ttl = _getlong(*cp); 537 *cp += INT32SZ; 538 539 /* rdata size */ 540 curr->size = _getshort(*cp); 541 *cp += INT16SZ; 542 543 /* rdata itself */ 544 curr->rdata = malloc(curr->size); 545 if (curr->rdata == NULL) { 546 free_dns_rr(head); 547 return (NULL); 548 } 549 memcpy(curr->rdata, *cp, curr->size); 550 *cp += curr->size; 551 } 552 553 return (head); 554 } 555 556 static void 557 free_dns_query(struct dns_query *p) 558 { 559 if (p == NULL) 560 return; 561 562 if (p->name) 563 free(p->name); 564 free_dns_query(p->next); 565 free(p); 566 } 567 568 static void 569 free_dns_rr(struct dns_rr *p) 570 { 571 if (p == NULL) 572 return; 573 574 if (p->name) 575 free(p->name); 576 if (p->rdata) 577 free(p->rdata); 578 free_dns_rr(p->next); 579 free(p); 580 } 581 582 static void 583 free_dns_response(struct dns_response *p) 584 { 585 if (p == NULL) 586 return; 587 588 free_dns_query(p->query); 589 free_dns_rr(p->answer); 590 free_dns_rr(p->authority); 591 free_dns_rr(p->additional); 592 free(p); 593 } 594 595 static int 596 count_dns_rr(struct dns_rr *p, u_int16_t class, u_int16_t type) 597 { 598 int n = 0; 599 600 while(p) { 601 if (p->class == class && p->type == type) 602 n++; 603 p = p->next; 604 } 605 606 return (n); 607 } 608 609 #endif /* !defined (HAVE_GETRRSETBYNAME) && !defined (HAVE_LDNS) */ 610