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
 199         srv->hostname = talloc_strdup( ctx, dcname );
 200
 201         DEBUG(10,("ads_dns_parse_rr_srv: Parsed %s [%u, %u, %u]\n",
 202                   srv->hostname,
 203                   srv->priority,
 204                   srv->weight,
 205                   srv->port));
 206
 207         return True;
 208 }
 209
 210 /*********************************************************************
 211 *********************************************************************/
 212
 213 static BOOL ads_dns_parse_rr_ns( TALLOC_CTX *ctx, uint8 *start, uint8 *end,
 214                        uint8 **ptr, struct dns_rr_ns *nsrec )
 215 {
 216         struct dns_rr rr;
 217         uint8 *p;
 218         pstring nsname;
 219         int namelen;
 220
 221         if ( !start || !end || !nsrec || !*ptr)
 222                 return -1;
 223
 224         /* Parse the RR entry.  Coming out of the this, ptr is at the beginning
 225            of the next record */
 226
 227         if ( !ads_dns_parse_rr( ctx, start, end, ptr, &rr ) ) {
 228                 DEBUG(1,("ads_dns_parse_rr_ns: Failed to parse RR record\n"));
 229                 return False;
 230         }
 231
 232         if ( rr.type != T_NS ) {
 233                 DEBUG(1,("ads_dns_parse_rr_ns: Bad answer type (%d)\n", rr.type));
 234                 return False;
 235         }
 236
 237         p = rr.rdata;
 238
 239         /* ame server hostname */
 240
 241         namelen = dn_expand( start, end, p, nsname, sizeof(nsname) );
 242         if ( namelen < 0 ) {
 243                 DEBUG(1,("ads_dns_parse_rr_ns: Failed to uncompress name!\n"));
 244                 return False;
 245         }
 246         nsrec->hostname = talloc_strdup( ctx, nsname );
 247
 248         return True;
 249 }
 250
 251 /*********************************************************************
 252  Sort SRV record list based on weight and priority.  See RFC 2782.
 253 *********************************************************************/
 254
 255 static int dnssrvcmp( struct dns_rr_srv *a, struct dns_rr_srv *b )
 256 {
 257         if ( a->priority == b->priority ) {
 258
 259                 /* randomize entries with an equal weight and priority */
 260                 if ( a->weight == b->weight )
 261                         return 0;
 262
 263                 /* higher weights should be sorted lower */
 264                 if ( a->weight > b->weight )
 265                         return -1;
 266                 else
 267                         return 1;
 268         }
 269
 270         if ( a->priority < b->priority )
 271                 return -1;
 272
 273         return 1;
 274 }
 275
 276 /*********************************************************************
 277  Simple wrapper for a DNS query
 278 *********************************************************************/
 279
 280 static NTSTATUS dns_send_req( TALLOC_CTX *ctx, const char *name, int q_type,
 281                               uint8 **buf, int *resp_length )
 282 {
 283         uint8 *buffer = NULL;
 284         size_t buf_len = 0;
 285         int resp_len = NS_PACKETSZ;
 286
 287         do {
 288                 if ( buffer )
 289                         TALLOC_FREE( buffer );
 290
 291                 buf_len = resp_len * sizeof(uint8);
 292
 293                 if (buf_len) {
 294                         if ( (buffer = TALLOC_ARRAY(ctx, uint8, buf_len)) == NULL ) {
 295                                 DEBUG(0,("ads_dns_lookup_srv: talloc() failed!\n"));
 296                                 return NT_STATUS_NO_MEMORY;
 297                         }
 298                 } else {
 299                         buffer = NULL;
 300                 }
 301
 302                 if ( (resp_len = res_query(name, C_IN, q_type, buffer, buf_len)) < 0 ) {
 303                         DEBUG(3,("ads_dns_lookup_srv: Failed to resolve %s (%s)\n", name, strerror(errno)));
 304                         TALLOC_FREE( buffer );
 305                         if (errno == ETIMEDOUT) {
 306                                 return NT_STATUS_IO_TIMEOUT;
 307                         }
 308                         if (errno == ECONNREFUSED) {
 309                                 return NT_STATUS_CONNECTION_REFUSED;
 310                         }
 311                         return NT_STATUS_UNSUCCESSFUL;
 312                 }
 313
 314                 /* On AIX, Solaris, and possibly some older glibc systems (e.g. SLES8)
 315                    truncated replies never give back a resp_len > buflen
 316                    which ends up causing DNS resolve failures on large tcp DNS replies */
 317
 318                 if (buf_len == resp_len) {
 319                         if (resp_len == MAX_DNS_PACKET_SIZE) {
 320                                 DEBUG(1,("dns_send_req: DNS reply too large when resolving %s\n",
 321                                         name));
 322                                 TALLOC_FREE( buffer );
 323                                 return NT_STATUS_BUFFER_TOO_SMALL;
 324                         }
 325
 326                         resp_len = MIN(resp_len*2, MAX_DNS_PACKET_SIZE);
 327                 }
 328
 329
 330         } while ( buf_len < resp_len && resp_len <= MAX_DNS_PACKET_SIZE );
 331
 332         *buf = buffer;
 333         *resp_length = resp_len;
 334
 335         return NT_STATUS_OK;
 336 }
 337
 338 /*********************************************************************
 339  Simple wrapper for a DNS SRV query
 340 *********************************************************************/
 341
 342 static NTSTATUS ads_dns_lookup_srv( TALLOC_CTX *ctx, const char *name, struct dns_rr_srv **dclist, int *numdcs )
 343 {
 344         uint8 *buffer = NULL;
 345         int resp_len = 0;
 346         struct dns_rr_srv *dcs = NULL;
 347         int query_count, answer_count, auth_count, additional_count;
 348         uint8 *p = buffer;
 349         int rrnum;
 350         int idx = 0;
 351         NTSTATUS status;
 352
 353         if ( !ctx || !name || !dclist ) {
 354                 return NT_STATUS_INVALID_PARAMETER;
 355         }
 356
 357         /* Send the request.  May have to loop several times in case
 358            of large replies */
 359
 360         status = dns_send_req( ctx, name, T_SRV, &buffer, &resp_len );
 361         if ( !NT_STATUS_IS_OK(status) ) {
 362                 DEBUG(3,("ads_dns_lookup_srv: Failed to send DNS query (%s)\n",
 363                         nt_errstr(status)));
 364                 return status;
 365         }
 366         p = buffer;
 367
 368         /* For some insane reason, the ns_initparse() et. al. routines are only
 369            available in libresolv.a, and not the shared lib.  Who knows why....
 370            So we have to parse the DNS reply ourselves */
 371
 372         /* Pull the answer RR's count from the header.  Use the NMB ordering macros */
 373
 374         query_count      = RSVAL( p, 4 );
 375         answer_count     = RSVAL( p, 6 );
 376         auth_count       = RSVAL( p, 8 );
 377         additional_count = RSVAL( p, 10 );
 378
 379         DEBUG(4,("ads_dns_lookup_srv: %d records returned in the answer section.\n",
 380                 answer_count));
 381
 382         if (answer_count) {
 383                 if ( (dcs = TALLOC_ZERO_ARRAY(ctx, struct dns_rr_srv, answer_count)) == NULL ) {
 384                         DEBUG(0,("ads_dns_lookup_srv: talloc() failure for %d char*'s\n",
 385                                 answer_count));
 386                         return NT_STATUS_NO_MEMORY;
 387                 }
 388         } else {
 389                 dcs = NULL;
 390         }
 391
 392         /* now skip the header */
 393
 394         p += NS_HFIXEDSZ;
 395
 396         /* parse the query section */
 397
 398         for ( rrnum=0; rrnum<query_count; rrnum++ ) {
 399                 struct dns_query q;
 400
 401                 if (!ads_dns_parse_query(ctx, buffer,
 402                                         buffer+resp_len, &p, &q)) {
 403                         DEBUG(1,("ads_dns_lookup_srv: "
 404                                  "Failed to parse query record [%d]!\n", rrnum));
 405                         return NT_STATUS_UNSUCCESSFUL;
 406                 }
 407         }
 408
 409         /* now we are at the answer section */
 410
 411         for ( rrnum=0; rrnum<answer_count; rrnum++ ) {
 412                 if (!ads_dns_parse_rr_srv(ctx, buffer, buffer+resp_len,
 413                                         &p, &dcs[rrnum])) {
 414                         DEBUG(1,("ads_dns_lookup_srv: "
 415                                  "Failed to parse answer recordi [%d]!\n", rrnum));
 416                         return NT_STATUS_UNSUCCESSFUL;
 417                 }
 418         }
 419         idx = rrnum;
 420
 421         /* Parse the authority section */
 422         /* just skip these for now */
 423
 424         for ( rrnum=0; rrnum<auth_count; rrnum++ ) {
 425                 struct dns_rr rr;
 426
 427                 if (!ads_dns_parse_rr( ctx, buffer,
 428                                         buffer+resp_len, &p, &rr)) {
 429                         DEBUG(1,("ads_dns_lookup_srv: "
 430                                  "Failed to parse authority record! [%d]\n", rrnum));
 431                         return NT_STATUS_UNSUCCESSFUL;
 432                 }
 433         }
 434
 435         /* Parse the additional records section */
 436
 437         for ( rrnum=0; rrnum<additional_count; rrnum++ ) {
 438                 struct dns_rr rr;
 439                 int i;
 440
 441                 if (!ads_dns_parse_rr(ctx, buffer, buffer+resp_len,
 442                                         &p, &rr)) {
 443                         DEBUG(1,("ads_dns_lookup_srv: Failed "
 444                                  "to parse additional records section! [%d]\n", rrnum));
 445                         return NT_STATUS_UNSUCCESSFUL;
 446                 }
 447
 448                 /* only interested in A records as a shortcut for having to come
 449                    back later and lookup the name.  For multi-homed hosts, the
 450                    number of additional records and exceed the number of answer
 451                    records. */
 452
 453
 454                 if ( (rr.type != T_A) || (rr.rdatalen != 4) )
 455                         continue;
 456
 457                 for ( i=0; i<idx; i++ ) {
 458                         if ( strcmp( rr.hostname, dcs[i].hostname ) == 0 ) {
 459                                 int num_ips = dcs[i].num_ips;
 460                                 uint8 *buf;
 461                                 struct in_addr *tmp_ips;
 462
 463                                 /* allocate new memory */
 464
 465                                 if ( dcs[i].num_ips == 0 ) {
 466                                         if ( (dcs[i].ips = TALLOC_ARRAY( dcs,
 467                                                 struct in_addr, 1 )) == NULL )
 468                                         {
 469                                                 return NT_STATUS_NO_MEMORY;
 470                                         }
 471                                 } else {
 472                                         if ( (tmp_ips = TALLOC_REALLOC_ARRAY( dcs, dcs[i].ips,
 473                                                 struct in_addr, dcs[i].num_ips+1)) == NULL )
 474                                         {
 475                                                 return NT_STATUS_NO_MEMORY;
 476                                         }
 477
 478                                         dcs[i].ips = tmp_ips;
 479                                 }
 480                                 dcs[i].num_ips++;
 481
 482                                 /* copy the new IP address */
 483
 484                                 buf = (uint8*)&dcs[i].ips[num_ips].s_addr;
 485                                 memcpy( buf, rr.rdata, 4 );
 486                         }
 487                 }
 488         }
 489
 490         qsort( dcs, idx, sizeof(struct dns_rr_srv), QSORT_CAST dnssrvcmp );
 491
 492         *dclist = dcs;
 493         *numdcs = idx;
 494
 495         return NT_STATUS_OK;
 496 }
 497
 498 /*********************************************************************
 499  Simple wrapper for a DNS NS query
 500 *********************************************************************/
 501
 502 NTSTATUS ads_dns_lookup_ns( TALLOC_CTX *ctx, const char *dnsdomain, struct dns_rr_ns **nslist, int *numns )
 503 {
 504         uint8 *buffer = NULL;
 505         int resp_len = 0;
 506         struct dns_rr_ns *nsarray = NULL;
 507         int query_count, answer_count, auth_count, additional_count;
 508         uint8 *p;
 509         int rrnum;
 510         int idx = 0;
 511         NTSTATUS status;
 512
 513         if ( !ctx || !dnsdomain || !nslist ) {
 514                 return NT_STATUS_INVALID_PARAMETER;
 515         }
 516
 517         /* Send the request.  May have to loop several times in case
 518            of large replies */
 519
 520         status = dns_send_req( ctx, dnsdomain, T_NS, &buffer, &resp_len );
 521         if ( !NT_STATUS_IS_OK(status) ) {
 522                 DEBUG(3,("ads_dns_lookup_ns: Failed to send DNS query (%s)\n",
 523                         nt_errstr(status)));
 524                 return status;
 525         }
 526         p = buffer;
 527
 528         /* For some insane reason, the ns_initparse() et. al. routines are only
 529            available in libresolv.a, and not the shared lib.  Who knows why....
 530            So we have to parse the DNS reply ourselves */
 531
 532         /* Pull the answer RR's count from the header.  Use the NMB ordering macros */
 533
 534         query_count      = RSVAL( p, 4 );
 535         answer_count     = RSVAL( p, 6 );
 536         auth_count       = RSVAL( p, 8 );
 537         additional_count = RSVAL( p, 10 );
 538
 539         DEBUG(4,("ads_dns_lookup_ns: %d records returned in the answer section.\n",
 540                 answer_count));
 541
 542         if (answer_count) {
 543                 if ( (nsarray = TALLOC_ARRAY(ctx, struct dns_rr_ns, answer_count)) == NULL ) {
 544                         DEBUG(0,("ads_dns_lookup_ns: talloc() failure for %d char*'s\n",
 545                                 answer_count));
 546                         return NT_STATUS_NO_MEMORY;
 547                 }
 548         } else {
 549                 nsarray = NULL;
 550         }
 551
 552         /* now skip the header */
 553
 554         p += NS_HFIXEDSZ;
 555
 556         /* parse the query section */
 557
 558         for ( rrnum=0; rrnum<query_count; rrnum++ ) {
 559                 struct dns_query q;
 560
 561                 if ( !ads_dns_parse_query( ctx, buffer, buffer+resp_len, &p, &q ) ) {
 562                         DEBUG(1,("ads_dns_lookup_ns: Failed to parse query record!\n"));
 563                         return NT_STATUS_UNSUCCESSFUL;
 564                 }
 565         }
 566
 567         /* now we are at the answer section */
 568
 569         for ( rrnum=0; rrnum<answer_count; rrnum++ ) {
 570                 if ( !ads_dns_parse_rr_ns( ctx, buffer, buffer+resp_len, &p, &nsarray[rrnum] ) ) {
 571                         DEBUG(1,("ads_dns_lookup_ns: Failed to parse answer record!\n"));
 572                         return NT_STATUS_UNSUCCESSFUL;
 573                 }
 574         }
 575         idx = rrnum;
 576
 577         /* Parse the authority section */
 578         /* just skip these for now */
 579
 580         for ( rrnum=0; rrnum<auth_count; rrnum++ ) {
 581                 struct dns_rr rr;
 582
 583                 if ( !ads_dns_parse_rr( ctx, buffer, buffer+resp_len, &p, &rr ) ) {
 584                         DEBUG(1,("ads_dns_lookup_ns: Failed to parse authority record!\n"));
 585                         return NT_STATUS_UNSUCCESSFUL;
 586                 }
 587         }
 588
 589         /* Parse the additional records section */
 590
 591         for ( rrnum=0; rrnum<additional_count; rrnum++ ) {
 592                 struct dns_rr rr;
 593                 int i;
 594
 595                 if ( !ads_dns_parse_rr( ctx, buffer, buffer+resp_len, &p, &rr ) ) {
 596                         DEBUG(1,("ads_dns_lookup_ns: Failed to parse additional records section!\n"));
 597                         return NT_STATUS_UNSUCCESSFUL;
 598                 }
 599
 600                 /* only interested in A records as a shortcut for having to come
 601                    back later and lookup the name */
 602
 603                 if ( (rr.type != T_A) || (rr.rdatalen != 4) )
 604                         continue;
 605
 606                 for ( i=0; i<idx; i++ ) {
 607                         if ( strcmp( rr.hostname, nsarray[i].hostname ) == 0 ) {
 608                                 uint8 *buf = (uint8*)&nsarray[i].ip.s_addr;
 609                                 memcpy( buf, rr.rdata, 4 );
 610                         }
 611                 }
 612         }
 613
 614         *nslist = nsarray;
 615         *numns = idx;
 616
 617         return NT_STATUS_OK;
 618 }
 619
 620 /****************************************************************************
 621  Store and fetch the AD client sitename.
 622 ****************************************************************************/
 623
 624 #define SITENAME_KEY    "AD_SITENAME/DOMAIN/%s"
 625
 626 static char *sitename_key(const char *realm)
 627 {
 628         char *keystr;
 629
 630         if (asprintf(&keystr, SITENAME_KEY, strupper_static(realm)) == -1) {
 631                 return NULL;
 632         }
 633
 634         return keystr;
 635 }
 636
 637
 638 /****************************************************************************
 639  Store the AD client sitename.
 640  We store indefinately as every new CLDAP query will re-write this.
 641 ****************************************************************************/
 642
 643 BOOL sitename_store(const char *realm, const char *sitename)
 644 {
 645         time_t expire;
 646         BOOL ret = False;
 647         char *key;
 648
 649         if (!gencache_init()) {
 650                 return False;
 651         }
 652
 653         if (!realm || (strlen(realm) == 0)) {
 654                 DEBUG(0,("sitename_store: no realm\n"));
 655                 return False;
 656         }
 657
 658         key = sitename_key(realm);
 659
 660         if (!sitename || (sitename && !*sitename)) {
 661                 DEBUG(5,("sitename_store: deleting empty sitename!\n"));
 662                 ret = gencache_del(key);
 663                 SAFE_FREE(key);
 664                 return ret;
 665         }
 666
 667         expire = get_time_t_max(); /* Store indefinately. */
 668
 669         DEBUG(10,("sitename_store: realm = [%s], sitename = [%s], expire = [%u]\n",
 670                 realm, sitename, (unsigned int)expire ));
 671
 672         ret = gencache_set( key, sitename, expire );
 673         SAFE_FREE(key);
 674         return ret;
 675 }
 676
 677 /****************************************************************************
 678  Fetch the AD client sitename.
 679  Caller must free.
 680 ****************************************************************************/
 681
 682 char *sitename_fetch(const char *realm)
 683 {
 684         char *sitename = NULL;
 685         time_t timeout;
 686         BOOL ret = False;
 687         const char *query_realm;
 688         char *key;
 689
 690         if (!gencache_init()) {
 691                 return NULL;
 692         }
 693
 694         if (!realm || (strlen(realm) == 0)) {
 695                 query_realm = lp_realm();
 696         } else {
 697                 query_realm = realm;
 698         }
 699
 700         key = sitename_key(query_realm);
 701
 702         ret = gencache_get( key, &sitename, &timeout );
 703         SAFE_FREE(key);
 704         if ( !ret ) {
 705                 DEBUG(5,("sitename_fetch: No stored sitename for %s\n",
 706                         query_realm));
 707         } else {
 708                 DEBUG(5,("sitename_fetch: Returning sitename for %s: \"%s\"\n",
 709                         query_realm, sitename ));
 710         }
 711         return sitename;
 712 }
 713
 714 /****************************************************************************
 715  Did the sitename change ?
 716 ****************************************************************************/
 717
 718 BOOL stored_sitename_changed(const char *realm, const char *sitename)
 719 {
 720         BOOL ret = False;
 721
 722         char *new_sitename;
 723
 724         if (!realm || (strlen(realm) == 0)) {
 725                 DEBUG(0,("stored_sitename_changed: no realm\n"));
 726                 return False;
 727         }
 728
 729         new_sitename = sitename_fetch(realm);
 730
 731         if (sitename && new_sitename && !strequal(sitename, new_sitename)) {
 732                 ret = True;
 733         } else if ((sitename && !new_sitename) ||
 734                         (!sitename && new_sitename)) {
 735                 ret = True;
 736         }
 737         SAFE_FREE(new_sitename);
 738         return ret;
 739 }
 740
 741 /********************************************************************
 742  Query with optional sitename.
 743 ********************************************************************/
 744
 745 NTSTATUS ads_dns_query_internal(TALLOC_CTX *ctx,
 746                                 const char *servicename,
 747                                 const char *realm,
 748                                 const char *sitename,
 749                                 struct dns_rr_srv **dclist,
 750                                 int *numdcs )
 751 {
 752         char *name;
 753         if (sitename) {
 754                 name = talloc_asprintf(ctx, "%s._tcp.%s._sites.dc._msdcs.%s",
 755                                 servicename, sitename, realm );
 756         } else {
 757                 name = talloc_asprintf(ctx, "%s._tcp.dc._msdcs.%s",
 758                                 servicename, realm );
 759         }
 760         if (!name) {
 761                 return NT_STATUS_NO_MEMORY;
 762         }
 763         return ads_dns_lookup_srv( ctx, name, dclist, numdcs );
 764 }
 765
 766 /********************************************************************
 767  Query for AD DC's.
 768 ********************************************************************/
 769
 770 NTSTATUS ads_dns_query_dcs(TALLOC_CTX *ctx,
 771                         const char *realm,
 772                         const char *sitename,
 773                         struct dns_rr_srv **dclist,
 774                         int *numdcs )
 775 {
 776         NTSTATUS status;
 777
 778         status = ads_dns_query_internal(ctx, "_ldap", realm, sitename,
 779                                         dclist, numdcs);
 780
 781         if (NT_STATUS_EQUAL(status, NT_STATUS_IO_TIMEOUT) ||
 782             NT_STATUS_EQUAL(status, NT_STATUS_CONNECTION_REFUSED)) {
 783                 return status;
 784         }
 785
 786         if (sitename && !NT_STATUS_IS_OK(status)) {
 787                 /* Sitename DNS query may have failed. Try without. */
 788                 status = ads_dns_query_internal(ctx, "_ldap", realm, NULL,
 789                                                 dclist, numdcs);
 790         }
 791         return status;
 792 }
 793
 794 /********************************************************************
 795  Query for AD KDC's.
 796  Even if our underlying kerberos libraries are UDP only, this
 797  is pretty safe as it's unlikely that a KDC supports TCP and not UDP.
 798 ********************************************************************/
 799
 800 NTSTATUS ads_dns_query_kdcs(TALLOC_CTX *ctx,
 801                         const char *realm,
 802                         const char *sitename,
 803                         struct dns_rr_srv **dclist,
 804                         int *numdcs )
 805 {
 806         NTSTATUS status;
 807
 808         status = ads_dns_query_internal(ctx, "_kerberos", realm, sitename,
 809                                         dclist, numdcs);
 810
 811         if (NT_STATUS_EQUAL(status, NT_STATUS_IO_TIMEOUT) ||
 812             NT_STATUS_EQUAL(status, NT_STATUS_CONNECTION_REFUSED)) {
 813                 return status;
 814         }
 815
 816         if (sitename && !NT_STATUS_IS_OK(status)) {
 817                 /* Sitename DNS query may have failed. Try without. */
 818                 status = ads_dns_query_internal(ctx, "_kerberos", realm, NULL,
 819                                                 dclist, numdcs);
 820         }
 821         return status;
 822 }