source3/libads/dns.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3    DNS utility library
   4    Copyright (C) Gerald (Jerry) Carter           2006.
   5    Copyright (C) Jeremy Allison                  2007.
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  19 */
  20
  21 #include "includes.h"
  22
  23 /* AIX resolv.h uses 'class' in struct ns_rr */
  24
  25 #if defined(AIX)
  26 #  if defined(class)
  27 #    undef class
  28 #  endif
  29 #endif  /* AIX */
  30
  31 /* resolver headers */
  32
  33 #include <sys/types.h>
  34 #include <netinet/in.h>
  35 #include <arpa/nameser.h>
  36 #include <resolv.h>
  37 #include <netdb.h>
  38
  39 #define MAX_DNS_PACKET_SIZE 0xffff
  40
  41 #ifdef NS_HFIXEDSZ      /* Bind 8/9 interface */
  42 #if !defined(C_IN)      /* AIX 5.3 already defines C_IN */
  43 #  define C_IN          ns_c_in
  44 #endif
  45 #if !defined(T_A)       /* AIX 5.3 already defines T_A */
  46 #  define T_A           ns_t_a
  47 #endif
  48
  49 #if defined(HAVE_IPV6)
  50 #if !defined(T_AAAA)
  51 #  define T_AAAA        ns_t_aaaa
  52 #endif
  53 #endif
  54
  55 #  define T_SRV         ns_t_srv
  56 #if !defined(T_NS)      /* AIX 5.3 already defines T_NS */
  57 #  define T_NS          ns_t_ns
  58 #endif
  59 #else
  60 #  ifdef HFIXEDSZ
  61 #    define NS_HFIXEDSZ HFIXEDSZ
  62 #  else
  63 #    define NS_HFIXEDSZ sizeof(HEADER)
  64 #  endif        /* HFIXEDSZ */
  65 #  ifdef PACKETSZ
  66 #    define NS_PACKETSZ PACKETSZ
  67 #  else /* 512 is usually the default */
  68 #    define NS_PACKETSZ 512
  69 #  endif        /* PACKETSZ */
  70 #  define T_SRV         33
  71 #endif
  72
  73 /*********************************************************************
  74 *********************************************************************/
  75
  76 static bool ads_dns_parse_query( TALLOC_CTX *ctx, uint8 *start, uint8 *end,
  77                           uint8 **ptr, struct dns_query *q )
  78 {
  79         uint8 *p = *ptr;
  80         char hostname[MAX_DNS_NAME_LENGTH];
  81         int namelen;
  82
  83         ZERO_STRUCTP( q );
  84
  85         if ( !start || !end || !q || !*ptr)
  86                 return False;
  87
  88         /* See RFC 1035 for details. If this fails, then return. */
  89
  90         namelen = dn_expand( start, end, p, hostname, sizeof(hostname) );
  91         if ( namelen < 0 ) {
  92                 return False;
  93         }
  94         p += namelen;
  95         q->hostname = talloc_strdup( ctx, hostname );
  96
  97         /* check that we have space remaining */
  98
  99         if ( PTR_DIFF(p+4, end) > 0 )
 100                 return False;
 101
 102         q->type     = RSVAL( p, 0 );
 103         q->in_class = RSVAL( p, 2 );
 104         p += 4;
 105
 106         *ptr = p;
 107
 108         return True;
 109 }
 110
 111 /*********************************************************************
 112 *********************************************************************/
 113
 114 static bool ads_dns_parse_rr( TALLOC_CTX *ctx, uint8 *start, uint8 *end,
 115                        uint8 **ptr, struct dns_rr *rr )
 116 {
 117         uint8 *p = *ptr;
 118         char hostname[MAX_DNS_NAME_LENGTH];
 119         int namelen;
 120
 121         if ( !start || !end || !rr || !*ptr)
 122                 return -1;
 123
 124         ZERO_STRUCTP( rr );
 125         /* pull the name from the answer */
 126
 127         namelen = dn_expand( start, end, p, hostname, sizeof(hostname) );
 128         if ( namelen < 0 ) {
 129                 return -1;
 130         }
 131         p += namelen;
 132         rr->hostname = talloc_strdup( ctx, hostname );
 133
 134         /* check that we have space remaining */
 135
 136         if ( PTR_DIFF(p+10, end) > 0 )
 137                 return False;
 138
 139         /* pull some values and then skip onto the string */
 140
 141         rr->type     = RSVAL(p, 0);
 142         rr->in_class = RSVAL(p, 2);
 143         rr->ttl      = RIVAL(p, 4);
 144         rr->rdatalen = RSVAL(p, 8);
 145
 146         p += 10;
 147
 148         /* sanity check the available space */
 149
 150         if ( PTR_DIFF(p+rr->rdatalen, end ) > 0 ) {
 151                 return False;
 152
 153         }
 154
 155         /* save a point to the rdata for this section */
 156
 157         rr->rdata = p;
 158         p += rr->rdatalen;
 159
 160         *ptr = p;
 161
 162         return True;
 163 }
 164
 165 /*********************************************************************
 166 *********************************************************************/
 167
 168 static bool ads_dns_parse_rr_srv( TALLOC_CTX *ctx, uint8 *start, uint8 *end,
 169                        uint8 **ptr, struct dns_rr_srv *srv )
 170 {
 171         struct dns_rr rr;
 172         uint8 *p;
 173         char dcname[MAX_DNS_NAME_LENGTH];
 174         int namelen;
 175
 176         if ( !start || !end || !srv || !*ptr)
 177                 return -1;
 178
 179         /* Parse the RR entry.  Coming out of the this, ptr is at the beginning
 180            of the next record */
 181
 182         if ( !ads_dns_parse_rr( ctx, start, end, ptr, &rr ) ) {
 183                 DEBUG(1,("ads_dns_parse_rr_srv: Failed to parse RR record\n"));
 184                 return False;
 185         }
 186
 187         if ( rr.type != T_SRV ) {
 188                 DEBUG(1,("ads_dns_parse_rr_srv: Bad answer type (%d)\n",
 189                                         rr.type));
 190                 return False;
 191         }
 192
 193         p = rr.rdata;
 194
 195         srv->priority = RSVAL(p, 0);
 196         srv->weight   = RSVAL(p, 2);
 197         srv->port     = RSVAL(p, 4);
 198
 199         p += 6;
 200
 201         namelen = dn_expand( start, end, p, dcname, sizeof(dcname) );
 202         if ( namelen < 0 ) {
 203                 DEBUG(1,("ads_dns_parse_rr_srv: Failed to uncompress name!\n"));
 204                 return False;
 205         }
 206
 207         srv->hostname = talloc_strdup( ctx, dcname );
 208
 209         DEBUG(10,("ads_dns_parse_rr_srv: Parsed %s [%u, %u, %u]\n",
 210                   srv->hostname,
 211                   srv->priority,
 212                   srv->weight,
 213                   srv->port));
 214
 215         return True;
 216 }
 217
 218 /*********************************************************************
 219 *********************************************************************/
 220
 221 static bool ads_dns_parse_rr_ns( TALLOC_CTX *ctx, uint8 *start, uint8 *end,
 222                        uint8 **ptr, struct dns_rr_ns *nsrec )
 223 {
 224         struct dns_rr rr;
 225         uint8 *p;
 226         char nsname[MAX_DNS_NAME_LENGTH];
 227         int namelen;
 228
 229         if ( !start || !end || !nsrec || !*ptr)
 230                 return -1;
 231
 232         /* Parse the RR entry.  Coming out of the this, ptr is at the beginning
 233            of the next record */
 234
 235         if ( !ads_dns_parse_rr( ctx, start, end, ptr, &rr ) ) {
 236                 DEBUG(1,("ads_dns_parse_rr_ns: Failed to parse RR record\n"));
 237                 return False;
 238         }
 239
 240         if ( rr.type != T_NS ) {
 241                 DEBUG(1,("ads_dns_parse_rr_ns: Bad answer type (%d)\n",
 242                                         rr.type));
 243                 return False;
 244         }
 245
 246         p = rr.rdata;
 247
 248         /* ame server hostname */
 249
 250         namelen = dn_expand( start, end, p, nsname, sizeof(nsname) );
 251         if ( namelen < 0 ) {
 252                 DEBUG(1,("ads_dns_parse_rr_ns: Failed to uncompress name!\n"));
 253                 return False;
 254         }
 255         nsrec->hostname = talloc_strdup( ctx, nsname );
 256
 257         return True;
 258 }
 259
 260 /*********************************************************************
 261  Sort SRV record list based on weight and priority.  See RFC 2782.
 262 *********************************************************************/
 263
 264 static int dnssrvcmp( struct dns_rr_srv *a, struct dns_rr_srv *b )
 265 {
 266         if ( a->priority == b->priority ) {
 267
 268                 /* randomize entries with an equal weight and priority */
 269                 if ( a->weight == b->weight )
 270                         return 0;
 271
 272                 /* higher weights should be sorted lower */
 273                 if ( a->weight > b->weight )
 274                         return -1;
 275                 else
 276                         return 1;
 277         }
 278
 279         if ( a->priority < b->priority )
 280                 return -1;
 281
 282         return 1;
 283 }
 284
 285 /*********************************************************************
 286  Simple wrapper for a DNS query
 287 *********************************************************************/
 288
 289 #define DNS_FAILED_WAITTIME          30
 290
 291 static NTSTATUS dns_send_req( TALLOC_CTX *ctx, const char *name, int q_type,
 292                               uint8 **buf, int *resp_length )
 293 {
 294         uint8 *buffer = NULL;
 295         size_t buf_len = 0;
 296         int resp_len = NS_PACKETSZ;
 297         static time_t last_dns_check = 0;
 298         static NTSTATUS last_dns_status = NT_STATUS_OK;
 299         time_t now = time(NULL);
 300
 301         /* Try to prevent bursts of DNS lookups if the server is down */
 302
 303         /* Protect against large clock changes */
 304
 305         if ( last_dns_check > now )
 306                 last_dns_check = 0;
 307
 308         /* IF we had a DNS timeout or a bad server and we are still
 309            in the 30 second cache window, just return the previous
 310            status and save the network timeout. */
 311
 312         if ( (NT_STATUS_EQUAL(last_dns_status,NT_STATUS_IO_TIMEOUT) ||
 313               NT_STATUS_EQUAL(last_dns_status,NT_STATUS_CONNECTION_REFUSED)) &&
 314              (last_dns_check+DNS_FAILED_WAITTIME) > now )
 315         {
 316                 DEBUG(10,("last_dns_check: Returning cached status (%s)\n",
 317                           nt_errstr(last_dns_status) ));
 318                 return last_dns_status;
 319         }
 320
 321         /* Send the Query */
 322         do {
 323                 if ( buffer )
 324                         TALLOC_FREE( buffer );
 325
 326                 buf_len = resp_len * sizeof(uint8);
 327
 328                 if (buf_len) {
 329                         if ((buffer = TALLOC_ARRAY(ctx, uint8, buf_len))
 330                                         == NULL ) {
 331                                 DEBUG(0,("ads_dns_lookup_srv: "
 332                                         "talloc() failed!\n"));
 333                                 last_dns_status = NT_STATUS_NO_MEMORY;
 334                                 last_dns_check = time(NULL);
 335                                 return last_dns_status;
 336                         }
 337                 }
 338
 339                 if ((resp_len = res_query(name, C_IN, q_type, buffer, buf_len))
 340                                 < 0 ) {
 341                         DEBUG(3,("ads_dns_lookup_srv: "
 342                                 "Failed to resolve %s (%s)\n",
 343                                 name, strerror(errno)));
 344                         TALLOC_FREE( buffer );
 345                         last_dns_status = NT_STATUS_UNSUCCESSFUL;
 346
 347                         if (errno == ETIMEDOUT) {
 348                                 last_dns_status = NT_STATUS_IO_TIMEOUT;
 349                         }
 350                         if (errno == ECONNREFUSED) {
 351                                 last_dns_status = NT_STATUS_CONNECTION_REFUSED;
 352                         }
 353                         last_dns_check = time(NULL);
 354                         return last_dns_status;
 355                 }
 356
 357                 /* On AIX, Solaris, and possibly some older glibc systems (e.g. SLES8)
 358                    truncated replies never give back a resp_len > buflen
 359                    which ends up causing DNS resolve failures on large tcp DNS replies */
 360
 361                 if (buf_len == resp_len) {
 362                         if (resp_len == MAX_DNS_PACKET_SIZE) {
 363                                 DEBUG(1,("dns_send_req: DNS reply too large when resolving %s\n",
 364                                         name));
 365                                 TALLOC_FREE( buffer );
 366                                 last_dns_status = NT_STATUS_BUFFER_TOO_SMALL;
 367                                 last_dns_check = time(NULL);
 368                                 return last_dns_status;
 369                         }
 370
 371                         resp_len = MIN(resp_len*2, MAX_DNS_PACKET_SIZE);
 372                 }
 373
 374
 375         } while ( buf_len < resp_len && resp_len <= MAX_DNS_PACKET_SIZE );
 376
 377         *buf = buffer;
 378         *resp_length = resp_len;
 379
 380         last_dns_check = time(NULL);
 381         last_dns_status = NT_STATUS_OK;
 382         return last_dns_status;
 383 }
 384
 385 /*********************************************************************
 386  Simple wrapper for a DNS SRV query
 387 *********************************************************************/
 388
 389 static NTSTATUS ads_dns_lookup_srv( TALLOC_CTX *ctx,
 390                                 const char *name,
 391                                 struct dns_rr_srv **dclist,
 392                                 int *numdcs)
 393 {
 394         uint8 *buffer = NULL;
 395         int resp_len = 0;
 396         struct dns_rr_srv *dcs = NULL;
 397         int query_count, answer_count, auth_count, additional_count;
 398         uint8 *p = buffer;
 399         int rrnum;
 400         int idx = 0;
 401         NTSTATUS status;
 402
 403         if ( !ctx || !name || !dclist ) {
 404                 return NT_STATUS_INVALID_PARAMETER;
 405         }
 406
 407         /* Send the request.  May have to loop several times in case
 408            of large replies */
 409
 410         status = dns_send_req( ctx, name, T_SRV, &buffer, &resp_len );
 411         if ( !NT_STATUS_IS_OK(status) ) {
 412                 DEBUG(3,("ads_dns_lookup_srv: Failed to send DNS query (%s)\n",
 413                         nt_errstr(status)));
 414                 return status;
 415         }
 416         p = buffer;
 417
 418         /* For some insane reason, the ns_initparse() et. al. routines are only
 419            available in libresolv.a, and not the shared lib.  Who knows why....
 420            So we have to parse the DNS reply ourselves */
 421
 422         /* Pull the answer RR's count from the header.
 423          * Use the NMB ordering macros */
 424
 425         query_count      = RSVAL( p, 4 );
 426         answer_count     = RSVAL( p, 6 );
 427         auth_count       = RSVAL( p, 8 );
 428         additional_count = RSVAL( p, 10 );
 429
 430         DEBUG(4,("ads_dns_lookup_srv: "
 431                 "%d records returned in the answer section.\n",
 432                 answer_count));
 433
 434         if (answer_count) {
 435                 if ((dcs = TALLOC_ZERO_ARRAY(ctx, struct dns_rr_srv,
 436                                                 answer_count)) == NULL ) {
 437                         DEBUG(0,("ads_dns_lookup_srv: "
 438                                 "talloc() failure for %d char*'s\n",
 439                                 answer_count));
 440                         return NT_STATUS_NO_MEMORY;
 441                 }
 442         } else {
 443                 dcs = NULL;
 444         }
 445
 446         /* now skip the header */
 447
 448         p += NS_HFIXEDSZ;
 449
 450         /* parse the query section */
 451
 452         for ( rrnum=0; rrnum<query_count; rrnum++ ) {
 453                 struct dns_query q;
 454
 455                 if (!ads_dns_parse_query(ctx, buffer,
 456                                         buffer+resp_len, &p, &q)) {
 457                         DEBUG(1,("ads_dns_lookup_srv: "
 458                                  "Failed to parse query record [%d]!\n", rrnum));
 459                         return NT_STATUS_UNSUCCESSFUL;
 460                 }
 461         }
 462
 463         /* now we are at the answer section */
 464
 465         for ( rrnum=0; rrnum<answer_count; rrnum++ ) {
 466                 if (!ads_dns_parse_rr_srv(ctx, buffer, buffer+resp_len,
 467                                         &p, &dcs[rrnum])) {
 468                         DEBUG(1,("ads_dns_lookup_srv: "
 469                                  "Failed to parse answer recordi [%d]!\n", rrnum));
 470                         return NT_STATUS_UNSUCCESSFUL;
 471                 }
 472         }
 473         idx = rrnum;
 474
 475         /* Parse the authority section */
 476         /* just skip these for now */
 477
 478         for ( rrnum=0; rrnum<auth_count; rrnum++ ) {
 479                 struct dns_rr rr;
 480
 481                 if (!ads_dns_parse_rr( ctx, buffer,
 482                                         buffer+resp_len, &p, &rr)) {
 483                         DEBUG(1,("ads_dns_lookup_srv: "
 484                                  "Failed to parse authority record! [%d]\n", rrnum));
 485                         return NT_STATUS_UNSUCCESSFUL;
 486                 }
 487         }
 488
 489         /* Parse the additional records section */
 490
 491         for ( rrnum=0; rrnum<additional_count; rrnum++ ) {
 492                 struct dns_rr rr;
 493                 int i;
 494
 495                 if (!ads_dns_parse_rr(ctx, buffer, buffer+resp_len,
 496                                         &p, &rr)) {
 497                         DEBUG(1,("ads_dns_lookup_srv: Failed "
 498                                  "to parse additional records section! [%d]\n", rrnum));
 499                         return NT_STATUS_UNSUCCESSFUL;
 500                 }
 501
 502                 /* Only interested in A or AAAA records as a shortcut for having
 503                  * to come back later and lookup the name. For multi-homed
 504                  * hosts, the number of additional records and exceed the
 505                  * number of answer records. */
 506
 507                 if (rr.type != T_A || rr.rdatalen != 4) {
 508 #if defined(HAVE_IPV6)
 509                         /* RFC2874 defines A6 records. This
 510                          * requires recusive and horribly complex lookups.
 511                          * Bastards. Ignore this for now.... JRA.
 512                          * Luckily RFC3363 reprecates A6 records.
 513                          */
 514                         if (rr.type != T_AAAA || rr.rdatalen != 16)
 515 #endif
 516                                 continue;
 517                 }
 518
 519                 for ( i=0; i<idx; i++ ) {
 520                         if ( strcmp( rr.hostname, dcs[i].hostname ) == 0 ) {
 521                                 int num_ips = dcs[i].num_ips;
 522                                 struct sockaddr_storage *tmp_ss_s;
 523
 524                                 /* allocate new memory */
 525
 526                                 if (dcs[i].num_ips == 0) {
 527                                         if ((dcs[i].ss_s = TALLOC_ARRAY(dcs,
 528                                                 struct sockaddr_storage, 1 ))
 529                                                         == NULL ) {
 530                                                 return NT_STATUS_NO_MEMORY;
 531                                         }
 532                                 } else {
 533                                         if ((tmp_ss_s = TALLOC_REALLOC_ARRAY(dcs,
 534                                                         dcs[i].ss_s,
 535                                                         struct sockaddr_storage,
 536                                                         dcs[i].num_ips+1))
 537                                                                 == NULL ) {
 538                                                 return NT_STATUS_NO_MEMORY;
 539                                         }
 540
 541                                         dcs[i].ss_s = tmp_ss_s;
 542                                 }
 543                                 dcs[i].num_ips++;
 544
 545                                 /* copy the new IP address */
 546                                 if (rr.type == T_A) {
 547                                         struct in_addr ip;
 548                                         memcpy(&ip, rr.rdata, 4);
 549                                         in_addr_to_sockaddr_storage(
 550                                                         &dcs[i].ss_s[num_ips],
 551                                                         ip);
 552                                 }
 553 #if defined(HAVE_IPV6)
 554                                 if (rr.type == T_AAAA) {
 555                                         struct in6_addr ip6;
 556                                         memcpy(&ip6, rr.rdata, rr.rdatalen);
 557                                         in6_addr_to_sockaddr_storage(
 558                                                         &dcs[i].ss_s[num_ips],
 559                                                         ip6);
 560                                 }
 561 #endif
 562                         }
 563                 }
 564         }
 565
 566         TYPESAFE_QSORT(dcs, idx, dnssrvcmp );
 567
 568         *dclist = dcs;
 569         *numdcs = idx;
 570
 571         return NT_STATUS_OK;
 572 }
 573
 574 /*********************************************************************
 575  Simple wrapper for a DNS NS query
 576 *********************************************************************/
 577
 578 NTSTATUS ads_dns_lookup_ns(TALLOC_CTX *ctx,
 579                                 const char *dnsdomain,
 580                                 struct dns_rr_ns **nslist,
 581                                 int *numns)
 582 {
 583         uint8 *buffer = NULL;
 584         int resp_len = 0;
 585         struct dns_rr_ns *nsarray = NULL;
 586         int query_count, answer_count, auth_count, additional_count;
 587         uint8 *p;
 588         int rrnum;
 589         int idx = 0;
 590         NTSTATUS status;
 591
 592         if ( !ctx || !dnsdomain || !nslist ) {
 593                 return NT_STATUS_INVALID_PARAMETER;
 594         }
 595
 596         /* Send the request.  May have to loop several times in case
 597            of large replies */
 598
 599         status = dns_send_req( ctx, dnsdomain, T_NS, &buffer, &resp_len );
 600         if ( !NT_STATUS_IS_OK(status) ) {
 601                 DEBUG(3,("ads_dns_lookup_ns: Failed to send DNS query (%s)\n",
 602                         nt_errstr(status)));
 603                 return status;
 604         }
 605         p = buffer;
 606
 607         /* For some insane reason, the ns_initparse() et. al. routines are only
 608            available in libresolv.a, and not the shared lib.  Who knows why....
 609            So we have to parse the DNS reply ourselves */
 610
 611         /* Pull the answer RR's count from the header.
 612          * Use the NMB ordering macros */
 613
 614         query_count      = RSVAL( p, 4 );
 615         answer_count     = RSVAL( p, 6 );
 616         auth_count       = RSVAL( p, 8 );
 617         additional_count = RSVAL( p, 10 );
 618
 619         DEBUG(4,("ads_dns_lookup_ns: "
 620                 "%d records returned in the answer section.\n",
 621                 answer_count));
 622
 623         if (answer_count) {
 624                 if ((nsarray = TALLOC_ARRAY(ctx, struct dns_rr_ns,
 625                                                 answer_count)) == NULL ) {
 626                         DEBUG(0,("ads_dns_lookup_ns: "
 627                                 "talloc() failure for %d char*'s\n",
 628                                 answer_count));
 629                         return NT_STATUS_NO_MEMORY;
 630                 }
 631         } else {
 632                 nsarray = NULL;
 633         }
 634
 635         /* now skip the header */
 636
 637         p += NS_HFIXEDSZ;
 638
 639         /* parse the query section */
 640
 641         for ( rrnum=0; rrnum<query_count; rrnum++ ) {
 642                 struct dns_query q;
 643
 644                 if (!ads_dns_parse_query(ctx, buffer, buffer+resp_len,
 645                                         &p, &q)) {
 646                         DEBUG(1,("ads_dns_lookup_ns: "
 647                                 " Failed to parse query record!\n"));
 648                         return NT_STATUS_UNSUCCESSFUL;
 649                 }
 650         }
 651
 652         /* now we are at the answer section */
 653
 654         for ( rrnum=0; rrnum<answer_count; rrnum++ ) {
 655                 if (!ads_dns_parse_rr_ns(ctx, buffer, buffer+resp_len,
 656                                         &p, &nsarray[rrnum])) {
 657                         DEBUG(1,("ads_dns_lookup_ns: "
 658                                 "Failed to parse answer record!\n"));
 659                         return NT_STATUS_UNSUCCESSFUL;
 660                 }
 661         }
 662         idx = rrnum;
 663
 664         /* Parse the authority section */
 665         /* just skip these for now */
 666
 667         for ( rrnum=0; rrnum<auth_count; rrnum++ ) {
 668                 struct dns_rr rr;
 669
 670                 if ( !ads_dns_parse_rr(ctx, buffer, buffer+resp_len,
 671                                         &p, &rr)) {
 672                         DEBUG(1,("ads_dns_lookup_ns: "
 673                                 "Failed to parse authority record!\n"));
 674                         return NT_STATUS_UNSUCCESSFUL;
 675                 }
 676         }
 677
 678         /* Parse the additional records section */
 679
 680         for ( rrnum=0; rrnum<additional_count; rrnum++ ) {
 681                 struct dns_rr rr;
 682                 int i;
 683
 684                 if (!ads_dns_parse_rr(ctx, buffer, buffer+resp_len,
 685                                         &p, &rr)) {
 686                         DEBUG(1,("ads_dns_lookup_ns: Failed "
 687                                 "to parse additional records section!\n"));
 688                         return NT_STATUS_UNSUCCESSFUL;
 689                 }
 690
 691                 /* only interested in A records as a shortcut for having to come
 692                    back later and lookup the name */
 693
 694                 if (rr.type != T_A || rr.rdatalen != 4) {
 695 #if defined(HAVE_IPV6)
 696                         if (rr.type != T_AAAA || rr.rdatalen != 16)
 697 #endif
 698                                 continue;
 699                 }
 700
 701                 for ( i=0; i<idx; i++ ) {
 702                         if (strcmp(rr.hostname, nsarray[i].hostname) == 0) {
 703                                 if (rr.type == T_A) {
 704                                         struct in_addr ip;
 705                                         memcpy(&ip, rr.rdata, 4);
 706                                         in_addr_to_sockaddr_storage(
 707                                                         &nsarray[i].ss,
 708                                                         ip);
 709                                 }
 710 #if defined(HAVE_IPV6)
 711                                 if (rr.type == T_AAAA) {
 712                                         struct in6_addr ip6;
 713                                         memcpy(&ip6, rr.rdata, rr.rdatalen);
 714                                         in6_addr_to_sockaddr_storage(
 715                                                         &nsarray[i].ss,
 716                                                         ip6);
 717                                 }
 718 #endif
 719                         }
 720                 }
 721         }
 722
 723         *nslist = nsarray;
 724         *numns = idx;
 725
 726         return NT_STATUS_OK;
 727 }
 728
 729 /********************************************************************
 730  Query with optional sitename.
 731 ********************************************************************/
 732
 733 static NTSTATUS ads_dns_query_internal(TALLOC_CTX *ctx,
 734                                        const char *servicename,
 735                                        const char *dc_pdc_gc_domains,
 736                                        const char *realm,
 737                                        const char *sitename,
 738                                        struct dns_rr_srv **dclist,
 739                                        int *numdcs )
 740 {
 741         char *name;
 742         if (sitename) {
 743                 name = talloc_asprintf(ctx, "%s._tcp.%s._sites.%s._msdcs.%s",
 744                                        servicename, sitename,
 745                                        dc_pdc_gc_domains, realm);
 746         } else {
 747                 name = talloc_asprintf(ctx, "%s._tcp.%s._msdcs.%s",
 748                                 servicename, dc_pdc_gc_domains, realm);
 749         }
 750         if (!name) {
 751                 return NT_STATUS_NO_MEMORY;
 752         }
 753         return ads_dns_lookup_srv( ctx, name, dclist, numdcs );
 754 }
 755
 756 /********************************************************************
 757  Query for AD DC's.
 758 ********************************************************************/
 759
 760 NTSTATUS ads_dns_query_dcs(TALLOC_CTX *ctx,
 761                            const char *realm,
 762                            const char *sitename,
 763                            struct dns_rr_srv **dclist,
 764                            int *numdcs )
 765 {
 766         NTSTATUS status;
 767
 768         status = ads_dns_query_internal(ctx, "_ldap", "dc", realm, sitename,
 769                                         dclist, numdcs);
 770
 771         if (NT_STATUS_EQUAL(status, NT_STATUS_IO_TIMEOUT) ||
 772             NT_STATUS_EQUAL(status, NT_STATUS_CONNECTION_REFUSED)) {
 773                 return status;
 774         }
 775
 776         if (sitename &&
 777             ((!NT_STATUS_IS_OK(status)) ||
 778              (NT_STATUS_IS_OK(status) && (numdcs == 0)))) {
 779                 /* Sitename DNS query may have failed. Try without. */
 780                 status = ads_dns_query_internal(ctx, "_ldap", "dc", realm,
 781                                                 NULL, dclist, numdcs);
 782         }
 783         return status;
 784 }
 785
 786 /********************************************************************
 787  Query for AD GC's.
 788 ********************************************************************/
 789
 790 NTSTATUS ads_dns_query_gcs(TALLOC_CTX *ctx,
 791                            const char *realm,
 792                            const char *sitename,
 793                            struct dns_rr_srv **dclist,
 794                            int *numdcs )
 795 {
 796         NTSTATUS status;
 797
 798         status = ads_dns_query_internal(ctx, "_ldap", "gc", realm, sitename,
 799                                         dclist, numdcs);
 800
 801         if (NT_STATUS_EQUAL(status, NT_STATUS_IO_TIMEOUT) ||
 802             NT_STATUS_EQUAL(status, NT_STATUS_CONNECTION_REFUSED)) {
 803                 return status;
 804         }
 805
 806         if (sitename &&
 807             ((!NT_STATUS_IS_OK(status)) ||
 808              (NT_STATUS_IS_OK(status) && (numdcs == 0)))) {
 809                 /* Sitename DNS query may have failed. Try without. */
 810                 status = ads_dns_query_internal(ctx, "_ldap", "gc", realm,
 811                                                 NULL, dclist, numdcs);
 812         }
 813         return status;
 814 }
 815
 816 /********************************************************************
 817  Query for AD KDC's.
 818  Even if our underlying kerberos libraries are UDP only, this
 819  is pretty safe as it's unlikely that a KDC supports TCP and not UDP.
 820 ********************************************************************/
 821
 822 NTSTATUS ads_dns_query_kdcs(TALLOC_CTX *ctx,
 823                             const char *dns_forest_name,
 824                             const char *sitename,
 825                             struct dns_rr_srv **dclist,
 826                             int *numdcs )
 827 {
 828         NTSTATUS status;
 829
 830         status = ads_dns_query_internal(ctx, "_kerberos", "dc",
 831                                         dns_forest_name, sitename, dclist,
 832                                         numdcs);
 833
 834         if (NT_STATUS_EQUAL(status, NT_STATUS_IO_TIMEOUT) ||
 835             NT_STATUS_EQUAL(status, NT_STATUS_CONNECTION_REFUSED)) {
 836                 return status;
 837         }
 838
 839         if (sitename &&
 840             ((!NT_STATUS_IS_OK(status)) ||
 841              (NT_STATUS_IS_OK(status) && (numdcs == 0)))) {
 842                 /* Sitename DNS query may have failed. Try without. */
 843                 status = ads_dns_query_internal(ctx, "_kerberos", "dc",
 844                                                 dns_forest_name, NULL,
 845                                                 dclist, numdcs);
 846         }
 847         return status;
 848 }
 849
 850 /********************************************************************
 851  Query for AD PDC. Sitename is obsolete here.
 852 ********************************************************************/
 853
 854 NTSTATUS ads_dns_query_pdc(TALLOC_CTX *ctx,
 855                            const char *dns_domain_name,
 856                            struct dns_rr_srv **dclist,
 857                            int *numdcs )
 858 {
 859         return ads_dns_query_internal(ctx, "_ldap", "pdc", dns_domain_name,
 860                                       NULL, dclist, numdcs);
 861 }
 862
 863 /********************************************************************
 864  Query for AD DC by guid. Sitename is obsolete here.
 865 ********************************************************************/
 866
 867 NTSTATUS ads_dns_query_dcs_guid(TALLOC_CTX *ctx,
 868                                 const char *dns_forest_name,
 869                                 const struct GUID *domain_guid,
 870                                 struct dns_rr_srv **dclist,
 871                                 int *numdcs )
 872 {
 873         /*_ldap._tcp.DomainGuid.domains._msdcs.DnsForestName */
 874
 875         const char *domains;
 876         char *guid_string;
 877
 878         guid_string = GUID_string(ctx, domain_guid);
 879         if (!guid_string) {
 880                 return NT_STATUS_NO_MEMORY;
 881         }
 882
 883         /* little hack */
 884         domains = talloc_asprintf(ctx, "%s.domains", guid_string);
 885         if (!domains) {
 886                 return NT_STATUS_NO_MEMORY;
 887         }
 888         TALLOC_FREE(guid_string);
 889
 890         return ads_dns_query_internal(ctx, "_ldap", domains, dns_forest_name,
 891                                       NULL, dclist, numdcs);
 892 }