openbsd-compat/getrrsetbyname.c

   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 #ifndef HAVE_GETRRSETBYNAME
  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) */