source/libads/dns.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3    DNS utility library
   4    Copyright (C) Gerald (Jerry) Carter           2006.
   5
   6    This program is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 2 of the License, or
   9    (at your option) any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program; if not, write to the Free Software
  18    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  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 #  define T_SRV         ns_t_srv
  49 #if !defined(T_NS)      /* AIX 5.3 already defines T_NS */
  50 #  define T_NS          ns_t_ns
  51 #endif
  52 #else
  53 #  ifdef HFIXEDSZ
  54 #    define NS_HFIXEDSZ HFIXEDSZ
  55 #  else
  56 #    define NS_HFIXEDSZ sizeof(HEADER)
  57 #  endif        /* HFIXEDSZ */
  58 #  ifdef PACKETSZ
  59 #    define NS_PACKETSZ PACKETSZ
  60 #  else /* 512 is usually the default */
  61 #    define NS_PACKETSZ 512
  62 #  endif        /* PACKETSZ */
  63 #  define T_SRV         33
  64 #endif
  65
  66 /*********************************************************************
  67 *********************************************************************/
  68
  69 static BOOL ads_dns_parse_query( TALLOC_CTX *ctx, uint8 *start, uint8 *end,
  70                           uint8 **ptr, struct dns_query *q )
  71 {
  72         uint8 *p = *ptr;
  73         pstring hostname;
  74         int namelen;
  75
  76         ZERO_STRUCTP( q );
  77
  78         if ( !start || !end || !q || !*ptr)
  79                 return False;
  80
  81         /* See RFC 1035 for details. If this fails, then return. */
  82
  83         namelen = dn_expand( start, end, p, hostname, sizeof(hostname) );
  84         if ( namelen < 0 ) {
  85                 return False;
  86         }
  87         p += namelen;
  88         q->hostname = talloc_strdup( ctx, hostname );
  89
  90         /* check that we have space remaining */
  91
  92         if ( PTR_DIFF(p+4, end) > 0 )
  93                 return False;
  94
  95         q->type     = RSVAL( p, 0 );
  96         q->in_class = RSVAL( p, 2 );
  97         p += 4;
  98
  99         *ptr = p;
 100
 101         return True;
 102 }
 103
 104 /*********************************************************************
 105 *********************************************************************/
 106
 107 static BOOL ads_dns_parse_rr( TALLOC_CTX *ctx, uint8 *start, uint8 *end,
 108                        uint8 **ptr, struct dns_rr *rr )
 109 {
 110         uint8 *p = *ptr;
 111         pstring hostname;
 112         int namelen;
 113
 114         if ( !start || !end || !rr || !*ptr)
 115                 return -1;
 116
 117         ZERO_STRUCTP( rr );
 118         /* pull the name from the answer */
 119
 120         namelen = dn_expand( start, end, p, hostname, sizeof(hostname) );
 121         if ( namelen < 0 ) {
 122                 return -1;
 123         }
 124         p += namelen;
 125         rr->hostname = talloc_strdup( ctx, hostname );
 126
 127         /* check that we have space remaining */
 128
 129         if ( PTR_DIFF(p+10, end) > 0 )
 130                 return False;
 131
 132         /* pull some values and then skip onto the string */
 133
 134         rr->type     = RSVAL(p, 0);
 135         rr->in_class = RSVAL(p, 2);
 136         rr->ttl      = RIVAL(p, 4);
 137         rr->rdatalen = RSVAL(p, 8);
 138
 139         p += 10;
 140
 141         /* sanity check the available space */
 142
 143         if ( PTR_DIFF(p+rr->rdatalen, end ) > 0 ) {
 144                 return False;
 145
 146         }
 147
 148         /* save a point to the rdata for this section */
 149
 150         rr->rdata = p;
 151         p += rr->rdatalen;
 152
 153         *ptr = p;
 154
 155         return True;
 156 }
 157
 158 /*********************************************************************
 159 *********************************************************************/
 160
 161 static BOOL ads_dns_parse_rr_srv( TALLOC_CTX *ctx, uint8 *start, uint8 *end,
 162                        uint8 **ptr, struct dns_rr_srv *srv )
 163 {
 164         struct dns_rr rr;
 165         uint8 *p;
 166         pstring dcname;
 167         int namelen;
 168
 169         if ( !start || !end || !srv || !*ptr)
 170                 return -1;
 171
 172         /* Parse the RR entry.  Coming out of the this, ptr is at the beginning
 173            of the next record */
 174
 175         if ( !ads_dns_parse_rr( ctx, start, end, ptr, &rr ) ) {
 176                 DEBUG(1,("ads_dns_parse_rr_srv: Failed to parse RR record\n"));
 177                 return False;
 178         }
 179
 180         if ( rr.type != T_SRV ) {
 181                 DEBUG(1,("ads_dns_parse_rr_srv: Bad answer type (%d)\n", rr.type));
 182                 return False;
 183         }
 184
 185         p = rr.rdata;
 186
 187         srv->priority = RSVAL(p, 0);
 188         srv->weight   = RSVAL(p, 2);
 189         srv->port     = RSVAL(p, 4);
 190
 191         p += 6;
 192
 193         namelen = dn_expand( start, end, p, dcname, sizeof(dcname) );
 194         if ( namelen < 0 ) {
 195                 DEBUG(1,("ads_dns_parse_rr_srv: Failed to uncompress name!\n"));
 196                 return False;
 197         }
 198         srv->hostname = talloc_strdup( ctx, dcname );
 199
 200         return True;
 201 }
 202
 203 /*********************************************************************
 204 *********************************************************************/
 205
 206 static BOOL ads_dns_parse_rr_ns( TALLOC_CTX *ctx, uint8 *start, uint8 *end,
 207                        uint8 **ptr, struct dns_rr_ns *nsrec )
 208 {
 209         struct dns_rr rr;
 210         uint8 *p;
 211         pstring nsname;
 212         int namelen;
 213
 214         if ( !start || !end || !nsrec || !*ptr)
 215                 return -1;
 216
 217         /* Parse the RR entry.  Coming out of the this, ptr is at the beginning
 218            of the next record */
 219
 220         if ( !ads_dns_parse_rr( ctx, start, end, ptr, &rr ) ) {
 221                 DEBUG(1,("ads_dns_parse_rr_ns: Failed to parse RR record\n"));
 222                 return False;
 223         }
 224
 225         if ( rr.type != T_NS ) {
 226                 DEBUG(1,("ads_dns_parse_rr_ns: Bad answer type (%d)\n", rr.type));
 227                 return False;
 228         }
 229
 230         p = rr.rdata;
 231
 232         /* ame server hostname */
 233
 234         namelen = dn_expand( start, end, p, nsname, sizeof(nsname) );
 235         if ( namelen < 0 ) {
 236                 DEBUG(1,("ads_dns_parse_rr_ns: Failed to uncompress name!\n"));
 237                 return False;
 238         }
 239         nsrec->hostname = talloc_strdup( ctx, nsname );
 240
 241         return True;
 242 }
 243
 244 /*********************************************************************
 245  Sort SRV record list based on weight and priority.  See RFC 2782.
 246 *********************************************************************/
 247
 248 static int dnssrvcmp( struct dns_rr_srv *a, struct dns_rr_srv *b )
 249 {
 250         if ( a->priority == b->priority ) {
 251
 252                 /* randomize entries with an equal weight and priority */
 253                 if ( a->weight == b->weight )
 254                         return 0;
 255
 256                 /* higher weights should be sorted lower */
 257                 if ( a->weight > b->weight )
 258                         return -1;
 259                 else
 260                         return 1;
 261         }
 262
 263         if ( a->priority < b->priority )
 264                 return -1;
 265
 266         return 1;
 267 }
 268
 269 /*********************************************************************
 270  Simple wrapper for a DNS query
 271 *********************************************************************/
 272
 273 static NTSTATUS dns_send_req( TALLOC_CTX *ctx, const char *name, int q_type,
 274                               uint8 **buf, int *resp_length )
 275 {
 276         uint8 *buffer = NULL;
 277         size_t buf_len;
 278         int resp_len = NS_PACKETSZ;
 279
 280         do {
 281                 if ( buffer )
 282                         TALLOC_FREE( buffer );
 283
 284                 buf_len = resp_len * sizeof(uint8);
 285
 286                 if (buf_len) {
 287                         if ( (buffer = TALLOC_ARRAY(ctx, uint8, buf_len)) == NULL ) {
 288                                 DEBUG(0,("ads_dns_lookup_srv: talloc() failed!\n"));
 289                                 return NT_STATUS_NO_MEMORY;
 290                         }
 291                 } else {
 292                         buffer = NULL;
 293                 }
 294
 295                 if ( (resp_len = res_query(name, C_IN, q_type, buffer, buf_len)) < 0 ) {
 296                         DEBUG(3,("ads_dns_lookup_srv: Failed to resolve %s (%s)\n", name, strerror(errno)));
 297                         TALLOC_FREE( buffer );
 298                         if (errno == ETIMEDOUT) {
 299                                 return NT_STATUS_IO_TIMEOUT;
 300                         }
 301                         if (errno == ECONNREFUSED) {
 302                                 return NT_STATUS_CONNECTION_REFUSED;
 303                         }
 304                         return NT_STATUS_UNSUCCESSFUL;
 305                 }
 306         } while ( buf_len < resp_len && resp_len < MAX_DNS_PACKET_SIZE );
 307
 308         *buf = buffer;
 309         *resp_length = resp_len;
 310
 311         return NT_STATUS_OK;
 312 }
 313
 314 /*********************************************************************
 315  Simple wrapper for a DNS SRV query
 316 *********************************************************************/
 317
 318 static NTSTATUS ads_dns_lookup_srv( TALLOC_CTX *ctx, const char *name, struct dns_rr_srv **dclist, int *numdcs )
 319 {
 320         uint8 *buffer = NULL;
 321         int resp_len = 0;
 322         struct dns_rr_srv *dcs = NULL;
 323         int query_count, answer_count, auth_count, additional_count;
 324         uint8 *p = buffer;
 325         int rrnum;
 326         int idx = 0;
 327         NTSTATUS status;
 328
 329         if ( !ctx || !name || !dclist ) {
 330                 return NT_STATUS_INVALID_PARAMETER;
 331         }
 332
 333         /* Send the request.  May have to loop several times in case
 334            of large replies */
 335
 336         status = dns_send_req( ctx, name, T_SRV, &buffer, &resp_len );
 337         if ( !NT_STATUS_IS_OK(status) ) {
 338                 DEBUG(3,("ads_dns_lookup_srv: Failed to send DNS query (%s)\n",
 339                         nt_errstr(status)));
 340                 return status;
 341         }
 342         p = buffer;
 343
 344         /* For some insane reason, the ns_initparse() et. al. routines are only
 345            available in libresolv.a, and not the shared lib.  Who knows why....
 346            So we have to parse the DNS reply ourselves */
 347
 348         /* Pull the answer RR's count from the header.  Use the NMB ordering macros */
 349
 350         query_count      = RSVAL( p, 4 );
 351         answer_count     = RSVAL( p, 6 );
 352         auth_count       = RSVAL( p, 8 );
 353         additional_count = RSVAL( p, 10 );
 354
 355         DEBUG(4,("ads_dns_lookup_srv: %d records returned in the answer section.\n",
 356                 answer_count));
 357
 358         if (answer_count) {
 359                 if ( (dcs = TALLOC_ZERO_ARRAY(ctx, struct dns_rr_srv, answer_count)) == NULL ) {
 360                         DEBUG(0,("ads_dns_lookup_srv: talloc() failure for %d char*'s\n",
 361                                 answer_count));
 362                         return NT_STATUS_NO_MEMORY;
 363                 }
 364         } else {
 365                 dcs = NULL;
 366         }
 367
 368         /* now skip the header */
 369
 370         p += NS_HFIXEDSZ;
 371
 372         /* parse the query section */
 373
 374         for ( rrnum=0; rrnum<query_count; rrnum++ ) {
 375                 struct dns_query q;
 376
 377                 if ( !ads_dns_parse_query( ctx, buffer, buffer+resp_len, &p, &q ) ) {
 378                         DEBUG(1,("ads_dns_lookup_srv: Failed to parse query record!\n"));
 379                         return NT_STATUS_UNSUCCESSFUL;
 380                 }
 381         }
 382
 383         /* now we are at the answer section */
 384
 385         for ( rrnum=0; rrnum<answer_count; rrnum++ ) {
 386                 if ( !ads_dns_parse_rr_srv( ctx, buffer, buffer+resp_len, &p, &dcs[rrnum] ) ) {
 387                         DEBUG(1,("ads_dns_lookup_srv: Failed to parse answer record!\n"));
 388                         return NT_STATUS_UNSUCCESSFUL;
 389                 }
 390         }
 391         idx = rrnum;
 392
 393         /* Parse the authority section */
 394         /* just skip these for now */
 395
 396         for ( rrnum=0; rrnum<auth_count; rrnum++ ) {
 397                 struct dns_rr rr;
 398
 399                 if ( !ads_dns_parse_rr( ctx, buffer, buffer+resp_len, &p, &rr ) ) {
 400                         DEBUG(1,("ads_dns_lookup_srv: Failed to parse authority record!\n"));
 401                         return NT_STATUS_UNSUCCESSFUL;
 402                 }
 403         }
 404
 405         /* Parse the additional records section */
 406
 407         for ( rrnum=0; rrnum<additional_count; rrnum++ ) {
 408                 struct dns_rr rr;
 409                 int i;
 410
 411                 if ( !ads_dns_parse_rr( ctx, buffer, buffer+resp_len, &p, &rr ) ) {
 412                         DEBUG(1,("ads_dns_lookup_srv: Failed to parse additional records section!\n"));
 413                         return NT_STATUS_UNSUCCESSFUL;
 414                 }
 415
 416                 /* only interested in A records as a shortcut for having to come
 417                    back later and lookup the name.  For multi-homed hosts, the
 418                    number of additional records and exceed the number of answer
 419                    records. */
 420
 421
 422                 if ( (rr.type != T_A) || (rr.rdatalen != 4) )
 423                         continue;
 424
 425                 for ( i=0; i<idx; i++ ) {
 426                         if ( strcmp( rr.hostname, dcs[i].hostname ) == 0 ) {
 427                                 int num_ips = dcs[i].num_ips;
 428                                 uint8 *buf;
 429                                 struct in_addr *tmp_ips;
 430
 431                                 /* allocate new memory */
 432
 433                                 if ( dcs[i].num_ips == 0 ) {
 434                                         if ( (dcs[i].ips = TALLOC_ARRAY( dcs,
 435                                                 struct in_addr, 1 )) == NULL )
 436                                         {
 437                                                 return NT_STATUS_NO_MEMORY;
 438                                         }
 439                                 } else {
 440                                         if ( (tmp_ips = TALLOC_REALLOC_ARRAY( dcs, dcs[i].ips,
 441                                                 struct in_addr, dcs[i].num_ips+1)) == NULL )
 442                                         {
 443                                                 return NT_STATUS_NO_MEMORY;
 444                                         }
 445
 446                                         dcs[i].ips = tmp_ips;
 447                                 }
 448                                 dcs[i].num_ips++;
 449
 450                                 /* copy the new IP address */
 451
 452                                 buf = (uint8*)&dcs[i].ips[num_ips].s_addr;
 453                                 memcpy( buf, rr.rdata, 4 );
 454                         }
 455                 }
 456         }
 457
 458         qsort( dcs, idx, sizeof(struct dns_rr_srv), QSORT_CAST dnssrvcmp );
 459
 460         *dclist = dcs;
 461         *numdcs = idx;
 462
 463         return NT_STATUS_OK;
 464 }
 465
 466 /*********************************************************************
 467  Simple wrapper for a DNS NS query
 468 *********************************************************************/
 469
 470 NTSTATUS ads_dns_lookup_ns( TALLOC_CTX *ctx, const char *dnsdomain, struct dns_rr_ns **nslist, int *numns )
 471 {
 472         uint8 *buffer = NULL;
 473         int resp_len = 0;
 474         struct dns_rr_ns *nsarray = NULL;
 475         int query_count, answer_count, auth_count, additional_count;
 476         uint8 *p;
 477         int rrnum;
 478         int idx = 0;
 479         NTSTATUS status;
 480
 481         if ( !ctx || !dnsdomain || !nslist ) {
 482                 return NT_STATUS_INVALID_PARAMETER;
 483         }
 484
 485         /* Send the request.  May have to loop several times in case
 486            of large replies */
 487
 488         status = dns_send_req( ctx, dnsdomain, T_NS, &buffer, &resp_len );
 489         if ( !NT_STATUS_IS_OK(status) ) {
 490                 DEBUG(3,("ads_dns_lookup_ns: Failed to send DNS query (%s)\n",
 491                         nt_errstr(status)));
 492                 return status;
 493         }
 494         p = buffer;
 495
 496         /* For some insane reason, the ns_initparse() et. al. routines are only
 497            available in libresolv.a, and not the shared lib.  Who knows why....
 498            So we have to parse the DNS reply ourselves */
 499
 500         /* Pull the answer RR's count from the header.  Use the NMB ordering macros */
 501
 502         query_count      = RSVAL( p, 4 );
 503         answer_count     = RSVAL( p, 6 );
 504         auth_count       = RSVAL( p, 8 );
 505         additional_count = RSVAL( p, 10 );
 506
 507         DEBUG(4,("ads_dns_lookup_ns: %d records returned in the answer section.\n",
 508                 answer_count));
 509
 510         if (answer_count) {
 511                 if ( (nsarray = TALLOC_ARRAY(ctx, struct dns_rr_ns, answer_count)) == NULL ) {
 512                         DEBUG(0,("ads_dns_lookup_ns: talloc() failure for %d char*'s\n",
 513                                 answer_count));
 514                         return NT_STATUS_NO_MEMORY;
 515                 }
 516         } else {
 517                 nsarray = NULL;
 518         }
 519
 520         /* now skip the header */
 521
 522         p += NS_HFIXEDSZ;
 523
 524         /* parse the query section */
 525
 526         for ( rrnum=0; rrnum<query_count; rrnum++ ) {
 527                 struct dns_query q;
 528
 529                 if ( !ads_dns_parse_query( ctx, buffer, buffer+resp_len, &p, &q ) ) {
 530                         DEBUG(1,("ads_dns_lookup_ns: Failed to parse query record!\n"));
 531                         return NT_STATUS_UNSUCCESSFUL;
 532                 }
 533         }
 534
 535         /* now we are at the answer section */
 536
 537         for ( rrnum=0; rrnum<answer_count; rrnum++ ) {
 538                 if ( !ads_dns_parse_rr_ns( ctx, buffer, buffer+resp_len, &p, &nsarray[rrnum] ) ) {
 539                         DEBUG(1,("ads_dns_lookup_ns: Failed to parse answer record!\n"));
 540                         return NT_STATUS_UNSUCCESSFUL;
 541                 }
 542         }
 543         idx = rrnum;
 544
 545         /* Parse the authority section */
 546         /* just skip these for now */
 547
 548         for ( rrnum=0; rrnum<auth_count; rrnum++ ) {
 549                 struct dns_rr rr;
 550
 551                 if ( !ads_dns_parse_rr( ctx, buffer, buffer+resp_len, &p, &rr ) ) {
 552                         DEBUG(1,("ads_dns_lookup_ns: Failed to parse authority record!\n"));
 553                         return NT_STATUS_UNSUCCESSFUL;
 554                 }
 555         }
 556
 557         /* Parse the additional records section */
 558
 559         for ( rrnum=0; rrnum<additional_count; rrnum++ ) {
 560                 struct dns_rr rr;
 561                 int i;
 562
 563                 if ( !ads_dns_parse_rr( ctx, buffer, buffer+resp_len, &p, &rr ) ) {
 564                         DEBUG(1,("ads_dns_lookup_ns: Failed to parse additional records section!\n"));
 565                         return NT_STATUS_UNSUCCESSFUL;
 566                 }
 567
 568                 /* only interested in A records as a shortcut for having to come
 569                    back later and lookup the name */
 570
 571                 if ( (rr.type != T_A) || (rr.rdatalen != 4) )
 572                         continue;
 573
 574                 for ( i=0; i<idx; i++ ) {
 575                         if ( strcmp( rr.hostname, nsarray[i].hostname ) == 0 ) {
 576                                 uint8 *buf = (uint8*)&nsarray[i].ip.s_addr;
 577                                 memcpy( buf, rr.rdata, 4 );
 578                         }
 579                 }
 580         }
 581
 582         *nslist = nsarray;
 583         *numns = idx;
 584
 585         return NT_STATUS_OK;
 586 }
 587
 588 /****************************************************************************
 589  Store and fetch the AD client sitename.
 590 ****************************************************************************/
 591
 592 #define SITENAME_KEY    "AD_SITENAME/DOMAIN/%s"
 593
 594 static char *sitename_key(const char *realm)
 595 {
 596         char *keystr;
 597
 598         if (asprintf(&keystr, SITENAME_KEY, strupper_static(realm)) == -1) {
 599                 return NULL;
 600         }
 601
 602         return keystr;
 603 }
 604
 605
 606 /****************************************************************************
 607  Store the AD client sitename.
 608  We store indefinately as every new CLDAP query will re-write this.
 609 ****************************************************************************/
 610
 611 BOOL sitename_store(const char *realm, const char *sitename)
 612 {
 613         time_t expire;
 614         BOOL ret = False;
 615         char *key;
 616
 617         if (!gencache_init()) {
 618                 return False;
 619         }
 620
 621         if (!realm || (strlen(realm) == 0)) {
 622                 DEBUG(0,("sitename_store: no realm\n"));
 623                 return False;
 624         }
 625
 626         key = sitename_key(realm);
 627
 628         if (!sitename || (sitename && !*sitename)) {
 629                 DEBUG(5,("sitename_store: deleting empty sitename!\n"));
 630                 ret = gencache_del(key);
 631                 SAFE_FREE(key);
 632                 return ret;
 633         }
 634
 635         expire = get_time_t_max(); /* Store indefinately. */
 636
 637         DEBUG(10,("sitename_store: realm = [%s], sitename = [%s], expire = [%u]\n",
 638                 realm, sitename, (unsigned int)expire ));
 639
 640         ret = gencache_set( key, sitename, expire );
 641         SAFE_FREE(key);
 642         return ret;
 643 }
 644
 645 /****************************************************************************
 646  Fetch the AD client sitename.
 647  Caller must free.
 648 ****************************************************************************/
 649
 650 char *sitename_fetch(const char *realm)
 651 {
 652         char *sitename = NULL;
 653         time_t timeout;
 654         BOOL ret = False;
 655         const char *query_realm;
 656         char *key;
 657
 658         if (!gencache_init()) {
 659                 return False;
 660         }
 661
 662         if (!realm || (strlen(realm) == 0)) {
 663                 query_realm = lp_realm();
 664         } else {
 665                 query_realm = realm;
 666         }
 667
 668         key = sitename_key(query_realm);
 669
 670         ret = gencache_get( key, &sitename, &timeout );
 671         SAFE_FREE(key);
 672         if ( !ret ) {
 673                 DEBUG(5,("sitename_fetch: No stored sitename for %s\n",
 674                         query_realm));
 675         } else {
 676                 DEBUG(5,("sitename_fetch: Returning sitename for %s: \"%s\"\n",
 677                         query_realm, sitename ));
 678         }
 679         return sitename;
 680 }
 681
 682 /****************************************************************************
 683  Did the sitename change ?
 684 ****************************************************************************/
 685
 686 BOOL stored_sitename_changed(const char *realm, const char *sitename)
 687 {
 688         BOOL ret = False;
 689
 690         char *new_sitename;
 691
 692         if (!realm || (strlen(realm) == 0)) {
 693                 DEBUG(0,("stored_sitename_changed: no realm\n"));
 694                 return False;
 695         }
 696
 697         new_sitename = sitename_fetch(realm);
 698
 699         if (sitename && new_sitename && !strequal(sitename, new_sitename)) {
 700                 ret = True;
 701         } else if ((sitename && !new_sitename) ||
 702                         (!sitename && new_sitename)) {
 703                 ret = True;
 704         }
 705         SAFE_FREE(new_sitename);
 706         return ret;
 707 }
 708
 709 /********************************************************************
 710  Query with optional sitename.
 711 ********************************************************************/
 712
 713 NTSTATUS ads_dns_query_internal(TALLOC_CTX *ctx,
 714                                 const char *servicename,
 715                                 const char *realm,
 716                                 const char *sitename,
 717                                 struct dns_rr_srv **dclist,
 718                                 int *numdcs )
 719 {
 720         char *name;
 721         if (sitename) {
 722                 name = talloc_asprintf(ctx, "%s._tcp.%s._sites.dc._msdcs.%s",
 723                                 servicename, sitename, realm );
 724         } else {
 725                 name = talloc_asprintf(ctx, "%s._tcp.dc._msdcs.%s",
 726                                 servicename, realm );
 727         }
 728         if (!name) {
 729                 return NT_STATUS_NO_MEMORY;
 730         }
 731         return ads_dns_lookup_srv( ctx, name, dclist, numdcs );
 732 }
 733
 734 /********************************************************************
 735  Query for AD DC's.
 736 ********************************************************************/
 737
 738 NTSTATUS ads_dns_query_dcs(TALLOC_CTX *ctx,
 739                         const char *realm,
 740                         const char *sitename,
 741                         struct dns_rr_srv **dclist,
 742                         int *numdcs )
 743 {
 744         NTSTATUS status;
 745
 746         status = ads_dns_query_internal(ctx, "_ldap", realm, sitename,
 747                                         dclist, numdcs);
 748
 749         if (NT_STATUS_EQUAL(status, NT_STATUS_IO_TIMEOUT) ||
 750             NT_STATUS_EQUAL(status, NT_STATUS_CONNECTION_REFUSED)) {
 751                 return status;
 752         }
 753
 754         if (sitename && !NT_STATUS_IS_OK(status)) {
 755                 /* Sitename DNS query may have failed. Try without. */
 756                 status = ads_dns_query_internal(ctx, "_ldap", realm, NULL,
 757                                                 dclist, numdcs);
 758         }
 759         return status;
 760 }
 761
 762 /********************************************************************
 763  Query for AD KDC's.
 764  Even if our underlying kerberos libraries are UDP only, this
 765  is pretty safe as it's unlikely that a KDC supports TCP and not UDP.
 766 ********************************************************************/
 767
 768 NTSTATUS ads_dns_query_kdcs(TALLOC_CTX *ctx,
 769                         const char *realm,
 770                         const char *sitename,
 771                         struct dns_rr_srv **dclist,
 772                         int *numdcs )
 773 {
 774         NTSTATUS status;
 775
 776         status = ads_dns_query_internal(ctx, "_kerberos", realm, sitename,
 777                                         dclist, numdcs);
 778
 779         if (NT_STATUS_EQUAL(status, NT_STATUS_IO_TIMEOUT) ||
 780             NT_STATUS_EQUAL(status, NT_STATUS_CONNECTION_REFUSED)) {
 781                 return status;
 782         }
 783
 784         if (sitename && !NT_STATUS_IS_OK(status)) {
 785                 /* Sitename DNS query may have failed. Try without. */
 786                 status = ads_dns_query_internal(ctx, "_kerberos", realm, NULL,
 787                                                 dclist, numdcs);
 788         }
 789         return status;
 790 }