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 register 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 register 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 * Routines to insert/extract short/long's. 114 */ 115 116 #ifndef HAVE__GETSHORT 117 static u_int16_t 118 _getshort(msgp) 119 register const u_char *msgp; 120 { 121 register u_int16_t u; 122 123 GETSHORT(u, msgp); 124 return (u); 125 } 126 #elif defined(HAVE_DECL__GETSHORT) && (HAVE_DECL__GETSHORT == 0) 127 u_int16_t _getshort(register const u_char *); 128 #endif 129 130 #ifndef HAVE__GETLONG 131 static u_int32_t 132 _getlong(msgp) 133 register const u_char *msgp; 134 { 135 register u_int32_t u; 136 137 GETLONG(u, msgp); 138 return (u); 139 } 140 #elif defined(HAVE_DECL__GETLONG) && (HAVE_DECL__GETLONG == 0) 141 u_int32_t _getlong(register const u_char *); 142 #endif 143 144 /* ************** */ 145 146 #define ANSWER_BUFFER_SIZE 0xffff 147 148 struct dns_query { 149 char *name; 150 u_int16_t type; 151 u_int16_t class; 152 struct dns_query *next; 153 }; 154 155 struct dns_rr { 156 char *name; 157 u_int16_t type; 158 u_int16_t class; 159 u_int16_t ttl; 160 u_int16_t size; 161 void *rdata; 162 struct dns_rr *next; 163 }; 164 165 struct dns_response { 166 HEADER header; 167 struct dns_query *query; 168 struct dns_rr *answer; 169 struct dns_rr *authority; 170 struct dns_rr *additional; 171 }; 172 173 static struct dns_response *parse_dns_response(const u_char *, int); 174 static struct dns_query *parse_dns_qsection(const u_char *, int, 175 const u_char **, int); 176 static struct dns_rr *parse_dns_rrsection(const u_char *, int, const u_char **, 177 int); 178 179 static void free_dns_query(struct dns_query *); 180 static void free_dns_rr(struct dns_rr *); 181 static void free_dns_response(struct dns_response *); 182 183 static int count_dns_rr(struct dns_rr *, u_int16_t, u_int16_t); 184 185 int 186 getrrsetbyname(const char *hostname, unsigned int rdclass, 187 unsigned int rdtype, unsigned int flags, 188 struct rrsetinfo **res) 189 { 190 struct __res_state *_resp = _THREAD_PRIVATE(_res, _res, &_res); 191 int result; 192 struct rrsetinfo *rrset = NULL; 193 struct dns_response *response = NULL; 194 struct dns_rr *rr; 195 struct rdatainfo *rdata; 196 int length; 197 unsigned int index_ans, index_sig; 198 u_char answer[ANSWER_BUFFER_SIZE]; 199 200 /* check for invalid class and type */ 201 if (rdclass > 0xffff || rdtype > 0xffff) { 202 result = ERRSET_INVAL; 203 goto fail; 204 } 205 206 /* don't allow queries of class or type ANY */ 207 if (rdclass == 0xff || rdtype == 0xff) { 208 result = ERRSET_INVAL; 209 goto fail; 210 } 211 212 /* don't allow flags yet, unimplemented */ 213 if (flags) { 214 result = ERRSET_INVAL; 215 goto fail; 216 } 217 218 /* initialize resolver */ 219 if ((_resp->options & RES_INIT) == 0 && res_init() == -1) { 220 result = ERRSET_FAIL; 221 goto fail; 222 } 223 224 #ifdef DEBUG 225 _resp->options |= RES_DEBUG; 226 #endif /* DEBUG */ 227 228 #ifdef RES_USE_DNSSEC 229 /* turn on DNSSEC if EDNS0 is configured */ 230 if (_resp->options & RES_USE_EDNS0) 231 _resp->options |= RES_USE_DNSSEC; 232 #endif /* RES_USE_DNSEC */ 233 234 /* make query */ 235 length = res_query(hostname, (signed int) rdclass, (signed int) rdtype, 236 answer, sizeof(answer)); 237 if (length < 0) { 238 switch(h_errno) { 239 case HOST_NOT_FOUND: 240 result = ERRSET_NONAME; 241 goto fail; 242 case NO_DATA: 243 result = ERRSET_NODATA; 244 goto fail; 245 default: 246 result = ERRSET_FAIL; 247 goto fail; 248 } 249 } 250 251 /* parse result */ 252 response = parse_dns_response(answer, length); 253 if (response == NULL) { 254 result = ERRSET_FAIL; 255 goto fail; 256 } 257 258 if (response->header.qdcount != 1) { 259 result = ERRSET_FAIL; 260 goto fail; 261 } 262 263 /* initialize rrset */ 264 rrset = calloc(1, sizeof(struct rrsetinfo)); 265 if (rrset == NULL) { 266 result = ERRSET_NOMEMORY; 267 goto fail; 268 } 269 rrset->rri_rdclass = response->query->class; 270 rrset->rri_rdtype = response->query->type; 271 rrset->rri_ttl = response->answer->ttl; 272 rrset->rri_nrdatas = response->header.ancount; 273 274 #ifdef HAVE_HEADER_AD 275 /* check for authenticated data */ 276 if (response->header.ad == 1) 277 rrset->rri_flags |= RRSET_VALIDATED; 278 #endif 279 280 /* copy name from answer section */ 281 rrset->rri_name = strdup(response->answer->name); 282 if (rrset->rri_name == NULL) { 283 result = ERRSET_NOMEMORY; 284 goto fail; 285 } 286 287 /* count answers */ 288 rrset->rri_nrdatas = count_dns_rr(response->answer, rrset->rri_rdclass, 289 rrset->rri_rdtype); 290 rrset->rri_nsigs = count_dns_rr(response->answer, rrset->rri_rdclass, 291 T_RRSIG); 292 293 /* allocate memory for answers */ 294 rrset->rri_rdatas = calloc(rrset->rri_nrdatas, 295 sizeof(struct rdatainfo)); 296 if (rrset->rri_rdatas == NULL) { 297 result = ERRSET_NOMEMORY; 298 goto fail; 299 } 300 301 /* allocate memory for signatures */ 302 if (rrset->rri_nsigs > 0) { 303 rrset->rri_sigs = calloc(rrset->rri_nsigs, sizeof(struct rdatainfo)); 304 if (rrset->rri_sigs == NULL) { 305 result = ERRSET_NOMEMORY; 306 goto fail; 307 } 308 } 309 310 /* copy answers & signatures */ 311 for (rr = response->answer, index_ans = 0, index_sig = 0; 312 rr; rr = rr->next) { 313 314 rdata = NULL; 315 316 if (rr->class == rrset->rri_rdclass && 317 rr->type == rrset->rri_rdtype) 318 rdata = &rrset->rri_rdatas[index_ans++]; 319 320 if (rr->class == rrset->rri_rdclass && 321 rr->type == T_RRSIG) 322 rdata = &rrset->rri_sigs[index_sig++]; 323 324 if (rdata) { 325 rdata->rdi_length = rr->size; 326 rdata->rdi_data = malloc(rr->size); 327 328 if (rdata->rdi_data == NULL) { 329 result = ERRSET_NOMEMORY; 330 goto fail; 331 } 332 memcpy(rdata->rdi_data, rr->rdata, rr->size); 333 } 334 } 335 free_dns_response(response); 336 337 *res = rrset; 338 return (ERRSET_SUCCESS); 339 340 fail: 341 if (rrset != NULL) 342 freerrset(rrset); 343 if (response != NULL) 344 free_dns_response(response); 345 return (result); 346 } 347 348 void 349 freerrset(struct rrsetinfo *rrset) 350 { 351 u_int16_t i; 352 353 if (rrset == NULL) 354 return; 355 356 if (rrset->rri_rdatas) { 357 for (i = 0; i < rrset->rri_nrdatas; i++) { 358 if (rrset->rri_rdatas[i].rdi_data == NULL) 359 break; 360 free(rrset->rri_rdatas[i].rdi_data); 361 } 362 free(rrset->rri_rdatas); 363 } 364 365 if (rrset->rri_sigs) { 366 for (i = 0; i < rrset->rri_nsigs; i++) { 367 if (rrset->rri_sigs[i].rdi_data == NULL) 368 break; 369 free(rrset->rri_sigs[i].rdi_data); 370 } 371 free(rrset->rri_sigs); 372 } 373 374 if (rrset->rri_name) 375 free(rrset->rri_name); 376 free(rrset); 377 } 378 379 /* 380 * DNS response parsing routines 381 */ 382 static struct dns_response * 383 parse_dns_response(const u_char *answer, int size) 384 { 385 struct dns_response *resp; 386 const u_char *cp; 387 388 /* allocate memory for the response */ 389 resp = calloc(1, sizeof(*resp)); 390 if (resp == NULL) 391 return (NULL); 392 393 /* initialize current pointer */ 394 cp = answer; 395 396 /* copy header */ 397 memcpy(&resp->header, cp, HFIXEDSZ); 398 cp += HFIXEDSZ; 399 400 /* fix header byte order */ 401 resp->header.qdcount = ntohs(resp->header.qdcount); 402 resp->header.ancount = ntohs(resp->header.ancount); 403 resp->header.nscount = ntohs(resp->header.nscount); 404 resp->header.arcount = ntohs(resp->header.arcount); 405 406 /* there must be at least one query */ 407 if (resp->header.qdcount < 1) { 408 free_dns_response(resp); 409 return (NULL); 410 } 411 412 /* parse query section */ 413 resp->query = parse_dns_qsection(answer, size, &cp, 414 resp->header.qdcount); 415 if (resp->header.qdcount && resp->query == NULL) { 416 free_dns_response(resp); 417 return (NULL); 418 } 419 420 /* parse answer section */ 421 resp->answer = parse_dns_rrsection(answer, size, &cp, 422 resp->header.ancount); 423 if (resp->header.ancount && resp->answer == NULL) { 424 free_dns_response(resp); 425 return (NULL); 426 } 427 428 /* parse authority section */ 429 resp->authority = parse_dns_rrsection(answer, size, &cp, 430 resp->header.nscount); 431 if (resp->header.nscount && resp->authority == NULL) { 432 free_dns_response(resp); 433 return (NULL); 434 } 435 436 /* parse additional section */ 437 resp->additional = parse_dns_rrsection(answer, size, &cp, 438 resp->header.arcount); 439 if (resp->header.arcount && resp->additional == NULL) { 440 free_dns_response(resp); 441 return (NULL); 442 } 443 444 return (resp); 445 } 446 447 static struct dns_query * 448 parse_dns_qsection(const u_char *answer, int size, const u_char **cp, int count) 449 { 450 struct dns_query *head, *curr, *prev; 451 int i, length; 452 char name[MAXDNAME]; 453 454 for (i = 1, head = NULL, prev = NULL; i <= count; i++, prev = curr) { 455 456 /* allocate and initialize struct */ 457 curr = calloc(1, sizeof(struct dns_query)); 458 if (curr == NULL) { 459 free_dns_query(head); 460 return (NULL); 461 } 462 if (head == NULL) 463 head = curr; 464 if (prev != NULL) 465 prev->next = curr; 466 467 /* name */ 468 length = dn_expand(answer, answer + size, *cp, name, 469 sizeof(name)); 470 if (length < 0) { 471 free_dns_query(head); 472 return (NULL); 473 } 474 curr->name = strdup(name); 475 if (curr->name == NULL) { 476 free_dns_query(head); 477 return (NULL); 478 } 479 *cp += length; 480 481 /* type */ 482 curr->type = _getshort(*cp); 483 *cp += INT16SZ; 484 485 /* class */ 486 curr->class = _getshort(*cp); 487 *cp += INT16SZ; 488 } 489 490 return (head); 491 } 492 493 static struct dns_rr * 494 parse_dns_rrsection(const u_char *answer, int size, const u_char **cp, 495 int count) 496 { 497 struct dns_rr *head, *curr, *prev; 498 int i, length; 499 char name[MAXDNAME]; 500 501 for (i = 1, head = NULL, prev = NULL; i <= count; i++, prev = curr) { 502 503 /* allocate and initialize struct */ 504 curr = calloc(1, sizeof(struct dns_rr)); 505 if (curr == NULL) { 506 free_dns_rr(head); 507 return (NULL); 508 } 509 if (head == NULL) 510 head = curr; 511 if (prev != NULL) 512 prev->next = curr; 513 514 /* name */ 515 length = dn_expand(answer, answer + size, *cp, name, 516 sizeof(name)); 517 if (length < 0) { 518 free_dns_rr(head); 519 return (NULL); 520 } 521 curr->name = strdup(name); 522 if (curr->name == NULL) { 523 free_dns_rr(head); 524 return (NULL); 525 } 526 *cp += length; 527 528 /* type */ 529 curr->type = _getshort(*cp); 530 *cp += INT16SZ; 531 532 /* class */ 533 curr->class = _getshort(*cp); 534 *cp += INT16SZ; 535 536 /* ttl */ 537 curr->ttl = _getlong(*cp); 538 *cp += INT32SZ; 539 540 /* rdata size */ 541 curr->size = _getshort(*cp); 542 *cp += INT16SZ; 543 544 /* rdata itself */ 545 curr->rdata = malloc(curr->size); 546 if (curr->rdata == NULL) { 547 free_dns_rr(head); 548 return (NULL); 549 } 550 memcpy(curr->rdata, *cp, curr->size); 551 *cp += curr->size; 552 } 553 554 return (head); 555 } 556 557 static void 558 free_dns_query(struct dns_query *p) 559 { 560 if (p == NULL) 561 return; 562 563 if (p->name) 564 free(p->name); 565 free_dns_query(p->next); 566 free(p); 567 } 568 569 static void 570 free_dns_rr(struct dns_rr *p) 571 { 572 if (p == NULL) 573 return; 574 575 if (p->name) 576 free(p->name); 577 if (p->rdata) 578 free(p->rdata); 579 free_dns_rr(p->next); 580 free(p); 581 } 582 583 static void 584 free_dns_response(struct dns_response *p) 585 { 586 if (p == NULL) 587 return; 588 589 free_dns_query(p->query); 590 free_dns_rr(p->answer); 591 free_dns_rr(p->authority); 592 free_dns_rr(p->additional); 593 free(p); 594 } 595 596 static int 597 count_dns_rr(struct dns_rr *p, u_int16_t class, u_int16_t type) 598 { 599 int n = 0; 600 601 while(p) { 602 if (p->class == class && p->type == type) 603 n++; 604 p = p->next; 605 } 606 607 return (n); 608 } 609 610 #endif /* !defined (HAVE_GETRRSETBYNAME) && !defined (HAVE_LDNS) */ 611