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 #include "libads/dns.h"
  23 #include "../librpc/ndr/libndr.h"
  24
  25 /* AIX resolv.h uses 'class' in struct ns_rr */
  26
  27 #if defined(AIX)
  28 #  if defined(class)
  29 #    undef class
  30 #  endif
  31 #endif  /* AIX */
  32
  33 /* resolver headers */
  34
  35 #include <sys/types.h>
  36 #include <netinet/in.h>
  37 #include <arpa/nameser.h>
  38 #include <resolv.h>
  39 #include <netdb.h>
  40
  41 #define MAX_DNS_PACKET_SIZE 0xffff
  42
  43 #ifdef NS_HFIXEDSZ      /* Bind 8/9 interface */
  44 #if !defined(C_IN)      /* AIX 5.3 already defines C_IN */
  45 #  define C_IN          ns_c_in
  46 #endif
  47 #if !defined(T_A)       /* AIX 5.3 already defines T_A */
  48 #  define T_A           ns_t_a
  49 #endif
  50
  51 #if defined(HAVE_IPV6)
  52 #if !defined(T_AAAA)
  53 #  define T_AAAA        ns_t_aaaa
  54 #endif
  55 #endif
  56
  57 #  define T_SRV         ns_t_srv
  58 #if !defined(T_NS)      /* AIX 5.3 already defines T_NS */
  59 #  define T_NS          ns_t_ns
  60 #endif
  61 #else
  62 #  ifdef HFIXEDSZ
  63 #    define NS_HFIXEDSZ HFIXEDSZ
  64 #  else
  65 #    define NS_HFIXEDSZ sizeof(HEADER)
  66 #  endif        /* HFIXEDSZ */
  67 #  ifdef PACKETSZ
  68 #    define NS_PACKETSZ PACKETSZ
  69 #  else /* 512 is usually the default */
  70 #    define NS_PACKETSZ 512
  71 #  endif        /* PACKETSZ */
  72 #  define T_SRV         33
  73 #endif
  74
  75 /*********************************************************************
  76 *********************************************************************/
  77
  78 static bool ads_dns_parse_query( TALLOC_CTX *ctx, uint8 *start, uint8 *end,
  79                           uint8 **ptr, struct dns_query *q )
  80 {
  81         uint8 *p = *ptr;
  82         char hostname[MAX_DNS_NAME_LENGTH];
  83         int namelen;
  84
  85         ZERO_STRUCTP( q );
  86
  87         if ( !start || !end || !q || !*ptr)
  88                 return False;
  89
  90         /* See RFC 1035 for details. If this fails, then return. */
  91
  92         namelen = dn_expand( start, end, p, hostname, sizeof(hostname) );
  93         if ( namelen < 0 ) {
  94                 return False;
  95         }
  96         p += namelen;
  97         q->hostname = talloc_strdup( ctx, hostname );
  98
  99         /* check that we have space remaining */
 100
 101         if ( PTR_DIFF(p+4, end) > 0 )
 102                 return False;
 103
 104         q->type     = RSVAL( p, 0 );
 105         q->in_class = RSVAL( p, 2 );
 106         p += 4;
 107
 108         *ptr = p;
 109
 110         return True;
 111 }
 112
 113 /*********************************************************************
 114 *********************************************************************/
 115
 116 static bool ads_dns_parse_rr( TALLOC_CTX *ctx, uint8 *start, uint8 *end,
 117                        uint8 **ptr, struct dns_rr *rr )
 118 {
 119         uint8 *p = *ptr;
 120         char hostname[MAX_DNS_NAME_LENGTH];
 121         int namelen;
 122
 123         if ( !start || !end || !rr || !*ptr)
 124                 return -1;
 125
 126         ZERO_STRUCTP( rr );
 127         /* pull the name from the answer */
 128
 129         namelen = dn_expand( start, end, p, hostname, sizeof(hostname) );
 130         if ( namelen < 0 ) {
 131                 return -1;
 132         }
 133         p += namelen;
 134         rr->hostname = talloc_strdup( ctx, hostname );
 135
 136         /* check that we have space remaining */
 137
 138         if ( PTR_DIFF(p+10, end) > 0 )
 139                 return False;
 140
 141         /* pull some values and then skip onto the string */
 142
 143         rr->type     = RSVAL(p, 0);
 144         rr->in_class = RSVAL(p, 2);
 145         rr->ttl      = RIVAL(p, 4);
 146         rr->rdatalen = RSVAL(p, 8);
 147
 148         p += 10;
 149
 150         /* sanity check the available space */
 151
 152         if ( PTR_DIFF(p+rr->rdatalen, end ) > 0 ) {
 153                 return False;
 154
 155         }
 156
 157         /* save a point to the rdata for this section */
 158
 159         rr->rdata = p;
 160         p += rr->rdatalen;
 161
 162         *ptr = p;
 163
 164         return True;
 165 }
 166
 167 /*********************************************************************
 168 *********************************************************************/
 169
 170 static bool ads_dns_parse_rr_srv( TALLOC_CTX *ctx, uint8 *start, uint8 *end,
 171                        uint8 **ptr, struct dns_rr_srv *srv )
 172 {
 173         struct dns_rr rr;
 174         uint8 *p;
 175         char dcname[MAX_DNS_NAME_LENGTH];
 176         int namelen;
 177
 178         if ( !start || !end || !srv || !*ptr)
 179                 return -1;
 180
 181         /* Parse the RR entry.  Coming out of the this, ptr is at the beginning
 182            of the next record */
 183
 184         if ( !ads_dns_parse_rr( ctx, start, end, ptr, &rr ) ) {
 185                 DEBUG(1,("ads_dns_parse_rr_srv: Failed to parse RR record\n"));
 186                 return False;
 187         }
 188
 189         if ( rr.type != T_SRV ) {
 190                 DEBUG(1,("ads_dns_parse_rr_srv: Bad answer type (%d)\n",
 191                                         rr.type));
 192                 return False;
 193         }
 194
 195         p = rr.rdata;
 196
 197         srv->priority = RSVAL(p, 0);
 198         srv->weight   = RSVAL(p, 2);
 199         srv->port     = RSVAL(p, 4);
 200
 201         p += 6;
 202
 203         namelen = dn_expand( start, end, p, dcname, sizeof(dcname) );
 204         if ( namelen < 0 ) {
 205                 DEBUG(1,("ads_dns_parse_rr_srv: Failed to uncompress name!\n"));
 206                 return False;
 207         }
 208
 209         srv->hostname = talloc_strdup( ctx, dcname );
 210
 211         DEBUG(10,("ads_dns_parse_rr_srv: Parsed %s [%u, %u, %u]\n",
 212                   srv->hostname,
 213                   srv->priority,
 214                   srv->weight,
 215                   srv->port));
 216
 217         return True;
 218 }
 219
 220 /*********************************************************************
 221 *********************************************************************/
 222
 223 static bool ads_dns_parse_rr_ns( TALLOC_CTX *ctx, uint8 *start, uint8 *end,
 224                        uint8 **ptr, struct dns_rr_ns *nsrec )
 225 {
 226         struct dns_rr rr;
 227         uint8 *p;
 228         char nsname[MAX_DNS_NAME_LENGTH];
 229         int namelen;
 230
 231         if ( !start || !end || !nsrec || !*ptr)
 232                 return -1;
 233
 234         /* Parse the RR entry.  Coming out of the this, ptr is at the beginning
 235            of the next record */
 236
 237         if ( !ads_dns_parse_rr( ctx, start, end, ptr, &rr ) ) {
 238                 DEBUG(1,("ads_dns_parse_rr_ns: Failed to parse RR record\n"));
 239                 return False;
 240         }
 241
 242         if ( rr.type != T_NS ) {
 243                 DEBUG(1,("ads_dns_parse_rr_ns: Bad answer type (%d)\n",
 244                                         rr.type));
 245                 return False;
 246         }
 247
 248         p = rr.rdata;
 249
 250         /* ame server hostname */
 251
 252         namelen = dn_expand( start, end, p, nsname, sizeof(nsname) );
 253         if ( namelen < 0 ) {
 254                 DEBUG(1,("ads_dns_parse_rr_ns: Failed to uncompress name!\n"));
 255                 return False;
 256         }
 257         nsrec->hostname = talloc_strdup( ctx, nsname );
 258
 259         return True;
 260 }
 261
 262 /*********************************************************************
 263  Sort SRV record list based on weight and priority.  See RFC 2782.
 264 *********************************************************************/
 265
 266 static int dnssrvcmp( struct dns_rr_srv *a, struct dns_rr_srv *b )
 267 {
 268         if ( a->priority == b->priority ) {
 269
 270                 /* randomize entries with an equal weight and priority */
 271                 if ( a->weight == b->weight )
 272                         return 0;
 273
 274                 /* higher weights should be sorted lower */
 275                 if ( a->weight > b->weight )
 276                         return -1;
 277                 else
 278                         return 1;
 279         }
 280
 281         if ( a->priority < b->priority )
 282                 return -1;
 283
 284         return 1;
 285 }
 286
 287 /*********************************************************************
 288  Simple wrapper for a DNS query
 289 *********************************************************************/
 290
 291 #define DNS_FAILED_WAITTIME          30
 292
 293 static NTSTATUS dns_send_req( TALLOC_CTX *ctx, const char *name, int q_type,
 294                               uint8 **buf, int *resp_length )
 295 {
 296         uint8 *buffer = NULL;
 297         size_t buf_len = 0;
 298         int resp_len = NS_PACKETSZ;
 299         static time_t last_dns_check = 0;
 300         static NTSTATUS last_dns_status = NT_STATUS_OK;
 301         time_t now = time_mono(NULL);
 302
 303         /* Try to prevent bursts of DNS lookups if the server is down */
 304
 305         /* Protect against large clock changes */
 306
 307         if ( last_dns_check > now )
 308                 last_dns_check = 0;
 309
 310         /* IF we had a DNS timeout or a bad server and we are still
 311            in the 30 second cache window, just return the previous
 312            status and save the network timeout. */
 313
 314         if ( (NT_STATUS_EQUAL(last_dns_status,NT_STATUS_IO_TIMEOUT) ||
 315               NT_STATUS_EQUAL(last_dns_status,NT_STATUS_CONNECTION_REFUSED)) &&
 316              (last_dns_check+DNS_FAILED_WAITTIME) > now )
 317         {
 318                 DEBUG(10,("last_dns_check: Returning cached status (%s)\n",
 319                           nt_errstr(last_dns_status) ));
 320                 return last_dns_status;
 321         }
 322
 323         /* Send the Query */
 324         do {
 325                 if ( buffer )
 326                         TALLOC_FREE( buffer );
 327
 328                 buf_len = resp_len * sizeof(uint8);
 329
 330                 if (buf_len) {
 331                         if ((buffer = TALLOC_ARRAY(ctx, uint8, buf_len))
 332                                         == NULL ) {
 333                                 DEBUG(0,("ads_dns_lookup_srv: "
 334                                         "talloc() failed!\n"));
 335                                 last_dns_status = NT_STATUS_NO_MEMORY;
 336                                 last_dns_check = time_mono(NULL);
 337                                 return last_dns_status;
 338                         }
 339                 }
 340
 341                 if ((resp_len = res_query(name, C_IN, q_type, buffer, buf_len))
 342                                 < 0 ) {
 343                         DEBUG(3,("ads_dns_lookup_srv: "
 344                                 "Failed to resolve %s (%s)\n",
 345                                 name, strerror(errno)));
 346                         TALLOC_FREE( buffer );
 347                         last_dns_status = NT_STATUS_UNSUCCESSFUL;
 348
 349                         if (errno == ETIMEDOUT) {
 350                                 last_dns_status = NT_STATUS_IO_TIMEOUT;
 351                         }
 352                         if (errno == ECONNREFUSED) {
 353                                 last_dns_status = NT_STATUS_CONNECTION_REFUSED;
 354                         }
 355                         last_dns_check = time_mono(NULL);
 356                         return last_dns_status;
 357                 }
 358
 359                 /* On AIX, Solaris, and possibly some older glibc systems (e.g. SLES8)
 360                    truncated replies never give back a resp_len > buflen
 361                    which ends up causing DNS resolve failures on large tcp DNS replies */
 362
 363                 if (buf_len == resp_len) {
 364                         if (resp_len == MAX_DNS_PACKET_SIZE) {
 365                                 DEBUG(1,("dns_send_req: DNS reply too large when resolving %s\n",
 366                                         name));
 367                                 TALLOC_FREE( buffer );
 368                                 last_dns_status = NT_STATUS_BUFFER_TOO_SMALL;
 369                                 last_dns_check = time_mono(NULL);
 370                                 return last_dns_status;
 371                         }
 372
 373                         resp_len = MIN(resp_len*2, MAX_DNS_PACKET_SIZE);
 374                 }
 375
 376
 377         } while ( buf_len < resp_len && resp_len <= MAX_DNS_PACKET_SIZE );
 378
 379         *buf = buffer;
 380         *resp_length = resp_len;
 381
 382         last_dns_check = time_mono(NULL);
 383         last_dns_status = NT_STATUS_OK;
 384         return last_dns_status;
 385 }
 386
 387 /*********************************************************************
 388  Simple wrapper for a DNS SRV query
 389 *********************************************************************/
 390
 391 static NTSTATUS ads_dns_lookup_srv( TALLOC_CTX *ctx,
 392                                 const char *name,
 393                                 struct dns_rr_srv **dclist,
 394                                 int *numdcs)
 395 {
 396         uint8 *buffer = NULL;
 397         int resp_len = 0;
 398         struct dns_rr_srv *dcs = NULL;
 399         int query_count, answer_count, auth_count, additional_count;
 400         uint8 *p = buffer;
 401         int rrnum;
 402         int idx = 0;
 403         NTSTATUS status;
 404
 405         if ( !ctx || !name || !dclist ) {
 406                 return NT_STATUS_INVALID_PARAMETER;
 407         }
 408
 409         /* Send the request.  May have to loop several times in case
 410            of large replies */
 411
 412         status = dns_send_req( ctx, name, T_SRV, &buffer, &resp_len );
 413         if ( !NT_STATUS_IS_OK(status) ) {
 414                 DEBUG(3,("ads_dns_lookup_srv: Failed to send DNS query (%s)\n",
 415                         nt_errstr(status)));
 416                 return status;
 417         }
 418         p = buffer;
 419
 420         /* For some insane reason, the ns_initparse() et. al. routines are only
 421            available in libresolv.a, and not the shared lib.  Who knows why....
 422            So we have to parse the DNS reply ourselves */
 423
 424         /* Pull the answer RR's count from the header.
 425          * Use the NMB ordering macros */
 426
 427         query_count      = RSVAL( p, 4 );
 428         answer_count     = RSVAL( p, 6 );
 429         auth_count       = RSVAL( p, 8 );
 430         additional_count = RSVAL( p, 10 );
 431
 432         DEBUG(4,("ads_dns_lookup_srv: "
 433                 "%d records returned in the answer section.\n",
 434                 answer_count));
 435
 436         if (answer_count) {
 437                 if ((dcs = TALLOC_ZERO_ARRAY(ctx, struct dns_rr_srv,
 438                                                 answer_count)) == NULL ) {
 439                         DEBUG(0,("ads_dns_lookup_srv: "
 440                                 "talloc() failure for %d char*'s\n",
 441                                 answer_count));
 442                         return NT_STATUS_NO_MEMORY;
 443                 }
 444         } else {
 445                 dcs = NULL;
 446         }
 447
 448         /* now skip the header */
 449
 450         p += NS_HFIXEDSZ;
 451
 452         /* parse the query section */
 453
 454         for ( rrnum=0; rrnum<query_count; rrnum++ ) {
 455                 struct dns_query q;
 456
 457                 if (!ads_dns_parse_query(ctx, buffer,
 458                                         buffer+resp_len, &p, &q)) {
 459                         DEBUG(1,("ads_dns_lookup_srv: "
 460                                  "Failed to parse query record [%d]!\n", rrnum));
 461                         return NT_STATUS_UNSUCCESSFUL;
 462                 }
 463         }
 464
 465         /* now we are at the answer section */
 466
 467         for ( rrnum=0; rrnum<answer_count; rrnum++ ) {
 468                 if (!ads_dns_parse_rr_srv(ctx, buffer, buffer+resp_len,
 469                                         &p, &dcs[rrnum])) {
 470                         DEBUG(1,("ads_dns_lookup_srv: "
 471                                  "Failed to parse answer recordi [%d]!\n", rrnum));
 472                         return NT_STATUS_UNSUCCESSFUL;
 473                 }
 474         }
 475         idx = rrnum;
 476
 477         /* Parse the authority section */
 478         /* just skip these for now */
 479
 480         for ( rrnum=0; rrnum<auth_count; rrnum++ ) {
 481                 struct dns_rr rr;
 482
 483                 if (!ads_dns_parse_rr( ctx, buffer,
 484                                         buffer+resp_len, &p, &rr)) {
 485                         DEBUG(1,("ads_dns_lookup_srv: "
 486                                  "Failed to parse authority record! [%d]\n", rrnum));
 487                         return NT_STATUS_UNSUCCESSFUL;
 488                 }
 489         }
 490
 491         /* Parse the additional records section */
 492
 493         for ( rrnum=0; rrnum<additional_count; rrnum++ ) {
 494                 struct dns_rr rr;
 495                 int i;
 496
 497                 if (!ads_dns_parse_rr(ctx, buffer, buffer+resp_len,
 498                                         &p, &rr)) {
 499                         DEBUG(1,("ads_dns_lookup_srv: Failed "
 500                                  "to parse additional records section! [%d]\n", rrnum));
 501                         return NT_STATUS_UNSUCCESSFUL;
 502                 }
 503
 504                 /* Only interested in A or AAAA records as a shortcut for having
 505                  * to come back later and lookup the name. For multi-homed
 506                  * hosts, the number of additional records and exceed the
 507                  * number of answer records. */
 508
 509                 if (rr.type != T_A || rr.rdatalen != 4) {
 510 #if defined(HAVE_IPV6)
 511                         /* RFC2874 defines A6 records. This
 512                          * requires recusive and horribly complex lookups.
 513                          * Bastards. Ignore this for now.... JRA.
 514                          * Luckily RFC3363 reprecates A6 records.
 515                          */
 516                         if (rr.type != T_AAAA || rr.rdatalen != 16)
 517 #endif
 518                                 continue;
 519                 }
 520
 521                 for ( i=0; i<idx; i++ ) {
 522                         if ( strcmp( rr.hostname, dcs[i].hostname ) == 0 ) {
 523                                 int num_ips = dcs[i].num_ips;
 524                                 struct sockaddr_storage *tmp_ss_s;
 525
 526                                 /* allocate new memory */
 527
 528                                 if (dcs[i].num_ips == 0) {
 529                                         if ((dcs[i].ss_s = TALLOC_ARRAY(dcs,
 530                                                 struct sockaddr_storage, 1 ))
 531                                                         == NULL ) {
 532                                                 return NT_STATUS_NO_MEMORY;
 533                                         }
 534                                 } else {
 535                                         if ((tmp_ss_s = TALLOC_REALLOC_ARRAY(dcs,
 536                                                         dcs[i].ss_s,
 537                                                         struct sockaddr_storage,
 538                                                         dcs[i].num_ips+1))
 539                                                                 == NULL ) {
 540                                                 return NT_STATUS_NO_MEMORY;
 541                                         }
 542
 543                                         dcs[i].ss_s = tmp_ss_s;
 544                                 }
 545                                 dcs[i].num_ips++;
 546
 547                                 /* copy the new IP address */
 548                                 if (rr.type == T_A) {
 549                                         struct in_addr ip;
 550                                         memcpy(&ip, rr.rdata, 4);
 551                                         in_addr_to_sockaddr_storage(
 552                                                         &dcs[i].ss_s[num_ips],
 553                                                         ip);
 554                                 }
 555 #if defined(HAVE_IPV6)
 556                                 if (rr.type == T_AAAA) {
 557                                         struct in6_addr ip6;
 558                                         memcpy(&ip6, rr.rdata, rr.rdatalen);
 559                                         in6_addr_to_sockaddr_storage(
 560                                                         &dcs[i].ss_s[num_ips],
 561                                                         ip6);
 562                                 }
 563 #endif
 564                         }
 565                 }
 566         }
 567
 568         TYPESAFE_QSORT(dcs, idx, dnssrvcmp );
 569
 570         *dclist = dcs;
 571         *numdcs = idx;
 572
 573         return NT_STATUS_OK;
 574 }
 575
 576 /*********************************************************************
 577  Simple wrapper for a DNS NS query
 578 *********************************************************************/
 579
 580 NTSTATUS ads_dns_lookup_ns(TALLOC_CTX *ctx,
 581                                 const char *dnsdomain,
 582                                 struct dns_rr_ns **nslist,
 583                                 int *numns)
 584 {
 585         uint8 *buffer = NULL;
 586         int resp_len = 0;
 587         struct dns_rr_ns *nsarray = NULL;
 588         int query_count, answer_count, auth_count, additional_count;
 589         uint8 *p;
 590         int rrnum;
 591         int idx = 0;
 592         NTSTATUS status;
 593
 594         if ( !ctx || !dnsdomain || !nslist ) {
 595                 return NT_STATUS_INVALID_PARAMETER;
 596         }
 597
 598         /* Send the request.  May have to loop several times in case
 599            of large replies */
 600
 601         status = dns_send_req( ctx, dnsdomain, T_NS, &buffer, &resp_len );
 602         if ( !NT_STATUS_IS_OK(status) ) {
 603                 DEBUG(3,("ads_dns_lookup_ns: Failed to send DNS query (%s)\n",
 604                         nt_errstr(status)));
 605                 return status;
 606         }
 607         p = buffer;
 608
 609         /* For some insane reason, the ns_initparse() et. al. routines are only
 610            available in libresolv.a, and not the shared lib.  Who knows why....
 611            So we have to parse the DNS reply ourselves */
 612
 613         /* Pull the answer RR's count from the header.
 614          * Use the NMB ordering macros */
 615
 616         query_count      = RSVAL( p, 4 );
 617         answer_count     = RSVAL( p, 6 );
 618         auth_count       = RSVAL( p, 8 );
 619         additional_count = RSVAL( p, 10 );
 620
 621         DEBUG(4,("ads_dns_lookup_ns: "
 622                 "%d records returned in the answer section.\n",
 623                 answer_count));
 624
 625         if (answer_count) {
 626                 if ((nsarray = TALLOC_ARRAY(ctx, struct dns_rr_ns,
 627                                                 answer_count)) == NULL ) {
 628                         DEBUG(0,("ads_dns_lookup_ns: "
 629                                 "talloc() failure for %d char*'s\n",
 630                                 answer_count));
 631                         return NT_STATUS_NO_MEMORY;
 632                 }
 633         } else {
 634                 nsarray = NULL;
 635         }
 636
 637         /* now skip the header */
 638
 639         p += NS_HFIXEDSZ;
 640
 641         /* parse the query section */
 642
 643         for ( rrnum=0; rrnum<query_count; rrnum++ ) {
 644                 struct dns_query q;
 645
 646                 if (!ads_dns_parse_query(ctx, buffer, buffer+resp_len,
 647                                         &p, &q)) {
 648                         DEBUG(1,("ads_dns_lookup_ns: "
 649                                 " Failed to parse query record!\n"));
 650                         return NT_STATUS_UNSUCCESSFUL;
 651                 }
 652         }
 653
 654         /* now we are at the answer section */
 655
 656         for ( rrnum=0; rrnum<answer_count; rrnum++ ) {
 657                 if (!ads_dns_parse_rr_ns(ctx, buffer, buffer+resp_len,
 658                                         &p, &nsarray[rrnum])) {
 659                         DEBUG(1,("ads_dns_lookup_ns: "
 660                                 "Failed to parse answer record!\n"));
 661                         return NT_STATUS_UNSUCCESSFUL;
 662                 }
 663         }
 664         idx = rrnum;
 665
 666         /* Parse the authority section */
 667         /* just skip these for now */
 668
 669         for ( rrnum=0; rrnum<auth_count; rrnum++ ) {
 670                 struct dns_rr rr;
 671
 672                 if ( !ads_dns_parse_rr(ctx, buffer, buffer+resp_len,
 673                                         &p, &rr)) {
 674                         DEBUG(1,("ads_dns_lookup_ns: "
 675                                 "Failed to parse authority record!\n"));
 676                         return NT_STATUS_UNSUCCESSFUL;
 677                 }
 678         }
 679
 680         /* Parse the additional records section */
 681
 682         for ( rrnum=0; rrnum<additional_count; rrnum++ ) {
 683                 struct dns_rr rr;
 684                 int i;
 685
 686                 if (!ads_dns_parse_rr(ctx, buffer, buffer+resp_len,
 687                                         &p, &rr)) {
 688                         DEBUG(1,("ads_dns_lookup_ns: Failed "
 689                                 "to parse additional records section!\n"));
 690                         return NT_STATUS_UNSUCCESSFUL;
 691                 }
 692
 693                 /* only interested in A records as a shortcut for having to come
 694                    back later and lookup the name */
 695
 696                 if (rr.type != T_A || rr.rdatalen != 4) {
 697 #if defined(HAVE_IPV6)
 698                         if (rr.type != T_AAAA || rr.rdatalen != 16)
 699 #endif
 700                                 continue;
 701                 }
 702
 703                 for ( i=0; i<idx; i++ ) {
 704                         if (strcmp(rr.hostname, nsarray[i].hostname) == 0) {
 705                                 if (rr.type == T_A) {
 706                                         struct in_addr ip;
 707                                         memcpy(&ip, rr.rdata, 4);
 708                                         in_addr_to_sockaddr_storage(
 709                                                         &nsarray[i].ss,
 710                                                         ip);
 711                                 }
 712 #if defined(HAVE_IPV6)
 713                                 if (rr.type == T_AAAA) {
 714                                         struct in6_addr ip6;
 715                                         memcpy(&ip6, rr.rdata, rr.rdatalen);
 716                                         in6_addr_to_sockaddr_storage(
 717                                                         &nsarray[i].ss,
 718                                                         ip6);
 719                                 }
 720 #endif
 721                         }
 722                 }
 723         }
 724
 725         *nslist = nsarray;
 726         *numns = idx;
 727
 728         return NT_STATUS_OK;
 729 }
 730
 731 /********************************************************************
 732  Query with optional sitename.
 733 ********************************************************************/
 734
 735 static NTSTATUS ads_dns_query_internal(TALLOC_CTX *ctx,
 736                                        const char *servicename,
 737                                        const char *dc_pdc_gc_domains,
 738                                        const char *realm,
 739                                        const char *sitename,
 740                                        struct dns_rr_srv **dclist,
 741                                        int *numdcs )
 742 {
 743         char *name;
 744         if (sitename) {
 745                 name = talloc_asprintf(ctx, "%s._tcp.%s._sites.%s._msdcs.%s",
 746                                        servicename, sitename,
 747                                        dc_pdc_gc_domains, realm);
 748         } else {
 749                 name = talloc_asprintf(ctx, "%s._tcp.%s._msdcs.%s",
 750                                 servicename, dc_pdc_gc_domains, realm);
 751         }
 752         if (!name) {
 753                 return NT_STATUS_NO_MEMORY;
 754         }
 755         return ads_dns_lookup_srv( ctx, name, dclist, numdcs );
 756 }
 757
 758 /********************************************************************
 759  Query for AD DC's.
 760 ********************************************************************/
 761
 762 NTSTATUS ads_dns_query_dcs(TALLOC_CTX *ctx,
 763                            const char *realm,
 764                            const char *sitename,
 765                            struct dns_rr_srv **dclist,
 766                            int *numdcs )
 767 {
 768         NTSTATUS status;
 769
 770         status = ads_dns_query_internal(ctx, "_ldap", "dc", realm, sitename,
 771                                         dclist, numdcs);
 772
 773         if (NT_STATUS_EQUAL(status, NT_STATUS_IO_TIMEOUT) ||
 774             NT_STATUS_EQUAL(status, NT_STATUS_CONNECTION_REFUSED)) {
 775                 return status;
 776         }
 777
 778         if (sitename &&
 779             ((!NT_STATUS_IS_OK(status)) ||
 780              (NT_STATUS_IS_OK(status) && (numdcs == 0)))) {
 781                 /* Sitename DNS query may have failed. Try without. */
 782                 status = ads_dns_query_internal(ctx, "_ldap", "dc", realm,
 783                                                 NULL, dclist, numdcs);
 784         }
 785         return status;
 786 }
 787
 788 /********************************************************************
 789  Query for AD GC's.
 790 ********************************************************************/
 791
 792 NTSTATUS ads_dns_query_gcs(TALLOC_CTX *ctx,
 793                            const char *realm,
 794                            const char *sitename,
 795                            struct dns_rr_srv **dclist,
 796                            int *numdcs )
 797 {
 798         NTSTATUS status;
 799
 800         status = ads_dns_query_internal(ctx, "_ldap", "gc", realm, sitename,
 801                                         dclist, numdcs);
 802
 803         if (NT_STATUS_EQUAL(status, NT_STATUS_IO_TIMEOUT) ||
 804             NT_STATUS_EQUAL(status, NT_STATUS_CONNECTION_REFUSED)) {
 805                 return status;
 806         }
 807
 808         if (sitename &&
 809             ((!NT_STATUS_IS_OK(status)) ||
 810              (NT_STATUS_IS_OK(status) && (numdcs == 0)))) {
 811                 /* Sitename DNS query may have failed. Try without. */
 812                 status = ads_dns_query_internal(ctx, "_ldap", "gc", realm,
 813                                                 NULL, dclist, numdcs);
 814         }
 815         return status;
 816 }
 817
 818 /********************************************************************
 819  Query for AD KDC's.
 820  Even if our underlying kerberos libraries are UDP only, this
 821  is pretty safe as it's unlikely that a KDC supports TCP and not UDP.
 822 ********************************************************************/
 823
 824 NTSTATUS ads_dns_query_kdcs(TALLOC_CTX *ctx,
 825                             const char *dns_forest_name,
 826                             const char *sitename,
 827                             struct dns_rr_srv **dclist,
 828                             int *numdcs )
 829 {
 830         NTSTATUS status;
 831
 832         status = ads_dns_query_internal(ctx, "_kerberos", "dc",
 833                                         dns_forest_name, sitename, dclist,
 834                                         numdcs);
 835
 836         if (NT_STATUS_EQUAL(status, NT_STATUS_IO_TIMEOUT) ||
 837             NT_STATUS_EQUAL(status, NT_STATUS_CONNECTION_REFUSED)) {
 838                 return status;
 839         }
 840
 841         if (sitename &&
 842             ((!NT_STATUS_IS_OK(status)) ||
 843              (NT_STATUS_IS_OK(status) && (numdcs == 0)))) {
 844                 /* Sitename DNS query may have failed. Try without. */
 845                 status = ads_dns_query_internal(ctx, "_kerberos", "dc",
 846                                                 dns_forest_name, NULL,
 847                                                 dclist, numdcs);
 848         }
 849         return status;
 850 }
 851
 852 /********************************************************************
 853  Query for AD PDC. Sitename is obsolete here.
 854 ********************************************************************/
 855
 856 NTSTATUS ads_dns_query_pdc(TALLOC_CTX *ctx,
 857                            const char *dns_domain_name,
 858                            struct dns_rr_srv **dclist,
 859                            int *numdcs )
 860 {
 861         return ads_dns_query_internal(ctx, "_ldap", "pdc", dns_domain_name,
 862                                       NULL, dclist, numdcs);
 863 }
 864
 865 /********************************************************************
 866  Query for AD DC by guid. Sitename is obsolete here.
 867 ********************************************************************/
 868
 869 NTSTATUS ads_dns_query_dcs_guid(TALLOC_CTX *ctx,
 870                                 const char *dns_forest_name,
 871                                 const struct GUID *domain_guid,
 872                                 struct dns_rr_srv **dclist,
 873                                 int *numdcs )
 874 {
 875         /*_ldap._tcp.DomainGuid.domains._msdcs.DnsForestName */
 876
 877         const char *domains;
 878         char *guid_string;
 879
 880         guid_string = GUID_string(ctx, domain_guid);
 881         if (!guid_string) {
 882                 return NT_STATUS_NO_MEMORY;
 883         }
 884
 885         /* little hack */
 886         domains = talloc_asprintf(ctx, "%s.domains", guid_string);
 887         if (!domains) {
 888                 return NT_STATUS_NO_MEMORY;
 889         }
 890         TALLOC_FREE(guid_string);
 891
 892         return ads_dns_query_internal(ctx, "_ldap", domains, dns_forest_name,
 893                                       NULL, dclist, numdcs);
 894 }