source3/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 3 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, see <http://www.gnu.org/licenses/>.
  18 */
  19
  20 #include "includes.h"
  21
  22 /* AIX resolv.h uses 'class' in struct ns_rr */
  23
  24 #if defined(AIX)
  25 #  if defined(class)
  26 #    undef class
  27 #  endif
  28 #endif  /* AIX */
  29
  30 /* resolver headers */
  31
  32 #include <sys/types.h>
  33 #include <netinet/in.h>
  34 #include <arpa/nameser.h>
  35 #include <resolv.h>
  36 #include <netdb.h>
  37
  38 #define MAX_DNS_PACKET_SIZE 0xffff
  39
  40 #ifdef NS_HFIXEDSZ      /* Bind 8/9 interface */
  41 #if !defined(C_IN)      /* AIX 5.3 already defines C_IN */
  42 #  define C_IN          ns_c_in
  43 #endif
  44 #if !defined(T_A)       /* AIX 5.3 already defines T_A */
  45 #  define T_A           ns_t_a
  46 #endif
  47 #  define T_SRV         ns_t_srv
  48 #if !defined(T_NS)      /* AIX 5.3 already defines T_NS */
  49 #  define T_NS          ns_t_ns
  50 #endif
  51 #else
  52 #  ifdef HFIXEDSZ
  53 #    define NS_HFIXEDSZ HFIXEDSZ
  54 #  else
  55 #    define NS_HFIXEDSZ sizeof(HEADER)
  56 #  endif        /* HFIXEDSZ */
  57 #  ifdef PACKETSZ
  58 #    define NS_PACKETSZ PACKETSZ
  59 #  else /* 512 is usually the default */
  60 #    define NS_PACKETSZ 512
  61 #  endif        /* PACKETSZ */
  62 #  define T_SRV         33
  63 #endif
  64
  65 /*********************************************************************
  66 *********************************************************************/
  67
  68 static BOOL ads_dns_parse_query( TALLOC_CTX *ctx, uint8 *start, uint8 *end,
  69                           uint8 **ptr, struct dns_query *q )
  70 {
  71         uint8 *p = *ptr;
  72         pstring hostname;
  73         int namelen;
  74
  75         ZERO_STRUCTP( q );
  76
  77         if ( !start || !end || !q || !*ptr)
  78                 return False;
  79
  80         /* See RFC 1035 for details. If this fails, then return. */
  81
  82         namelen = dn_expand( start, end, p, hostname, sizeof(hostname) );
  83         if ( namelen < 0 ) {
  84                 return False;
  85         }
  86         p += namelen;
  87         q->hostname = talloc_strdup( ctx, hostname );
  88
  89         /* check that we have space remaining */
  90
  91         if ( PTR_DIFF(p+4, end) > 0 )
  92                 return False;
  93
  94         q->type     = RSVAL( p, 0 );
  95         q->in_class = RSVAL( p, 2 );
  96         p += 4;
  97
  98         *ptr = p;
  99
 100         return True;
 101 }
 102
 103 /*********************************************************************
 104 *********************************************************************/
 105
 106 static BOOL ads_dns_parse_rr( TALLOC_CTX *ctx, uint8 *start, uint8 *end,
 107                        uint8 **ptr, struct dns_rr *rr )
 108 {
 109         uint8 *p = *ptr;
 110         pstring hostname;
 111         int namelen;
 112
 113         if ( !start || !end || !rr || !*ptr)
 114                 return -1;
 115
 116         ZERO_STRUCTP( rr );
 117         /* pull the name from the answer */
 118
 119         namelen = dn_expand( start, end, p, hostname, sizeof(hostname) );
 120         if ( namelen < 0 ) {
 121                 return -1;
 122         }
 123         p += namelen;
 124         rr->hostname = talloc_strdup( ctx, hostname );
 125
 126         /* check that we have space remaining */
 127
 128         if ( PTR_DIFF(p+10, end) > 0 )
 129                 return False;
 130
 131         /* pull some values and then skip onto the string */
 132
 133         rr->type     = RSVAL(p, 0);
 134         rr->in_class = RSVAL(p, 2);
 135         rr->ttl      = RIVAL(p, 4);
 136         rr->rdatalen = RSVAL(p, 8);
 137
 138         p += 10;
 139
 140         /* sanity check the available space */
 141
 142         if ( PTR_DIFF(p+rr->rdatalen, end ) > 0 ) {
 143                 return False;
 144
 145         }
 146
 147         /* save a point to the rdata for this section */
 148
 149         rr->rdata = p;
 150         p += rr->rdatalen;
 151
 152         *ptr = p;
 153
 154         return True;
 155 }
 156
 157 /*********************************************************************
 158 *********************************************************************/
 159
 160 static BOOL ads_dns_parse_rr_srv( TALLOC_CTX *ctx, uint8 *start, uint8 *end,
 161                        uint8 **ptr, struct dns_rr_srv *srv )
 162 {
 163         struct dns_rr rr;
 164         uint8 *p;
 165         pstring dcname;
 166         int namelen;
 167
 168         if ( !start || !end || !srv || !*ptr)
 169                 return -1;
 170
 171         /* Parse the RR entry.  Coming out of the this, ptr is at the beginning
 172            of the next record */
 173
 174         if ( !ads_dns_parse_rr( ctx, start, end, ptr, &rr ) ) {
 175                 DEBUG(1,("ads_dns_parse_rr_srv: Failed to parse RR record\n"));
 176                 return False;
 177         }
 178
 179         if ( rr.type != T_SRV ) {
 180                 DEBUG(1,("ads_dns_parse_rr_srv: Bad answer type (%d)\n", rr.type));
 181                 return False;
 182         }
 183
 184         p = rr.rdata;
 185
 186         srv->priority = RSVAL(p, 0);
 187         srv->weight   = RSVAL(p, 2);
 188         srv->port     = RSVAL(p, 4);
 189
 190         p += 6;
 191
 192         namelen = dn_expand( start, end, p, dcname, sizeof(dcname) );
 193         if ( namelen < 0 ) {
 194                 DEBUG(1,("ads_dns_parse_rr_srv: Failed to uncompress name!\n"));
 195                 return False;
 196         }
 197         srv->hostname = talloc_strdup( ctx, dcname );
 198
 199         return True;
 200 }
 201
 202 /*********************************************************************
 203 *********************************************************************/
 204
 205 static BOOL ads_dns_parse_rr_ns( TALLOC_CTX *ctx, uint8 *start, uint8 *end,
 206                        uint8 **ptr, struct dns_rr_ns *nsrec )
 207 {
 208         struct dns_rr rr;
 209         uint8 *p;
 210         pstring nsname;
 211         int namelen;
 212
 213         if ( !start || !end || !nsrec || !*ptr)
 214                 return -1;
 215
 216         /* Parse the RR entry.  Coming out of the this, ptr is at the beginning
 217            of the next record */
 218
 219         if ( !ads_dns_parse_rr( ctx, start, end, ptr, &rr ) ) {
 220                 DEBUG(1,("ads_dns_parse_rr_ns: Failed to parse RR record\n"));
 221                 return False;
 222         }
 223
 224         if ( rr.type != T_NS ) {
 225                 DEBUG(1,("ads_dns_parse_rr_ns: Bad answer type (%d)\n", rr.type));
 226                 return False;
 227         }
 228
 229         p = rr.rdata;
 230
 231         /* ame server hostname */
 232
 233         namelen = dn_expand( start, end, p, nsname, sizeof(nsname) );
 234         if ( namelen < 0 ) {
 235                 DEBUG(1,("ads_dns_parse_rr_ns: Failed to uncompress name!\n"));
 236                 return False;
 237         }
 238         nsrec->hostname = talloc_strdup( ctx, nsname );
 239
 240         return True;
 241 }
 242
 243 /*********************************************************************
 244  Sort SRV record list based on weight and priority.  See RFC 2782.
 245 *********************************************************************/
 246
 247 static int dnssrvcmp( struct dns_rr_srv *a, struct dns_rr_srv *b )
 248 {
 249         if ( a->priority == b->priority ) {
 250
 251                 /* randomize entries with an equal weight and priority */
 252                 if ( a->weight == b->weight )
 253                         return 0;
 254
 255                 /* higher weights should be sorted lower */
 256                 if ( a->weight > b->weight )
 257                         return -1;
 258                 else
 259                         return 1;
 260         }
 261
 262         if ( a->priority < b->priority )
 263                 return -1;
 264
 265         return 1;
 266 }
 267
 268 /*********************************************************************
 269  Simple wrapper for a DNS query
 270 *********************************************************************/
 271
 272 #define DNS_FAILED_WAITTIME          30
 273
 274 static NTSTATUS dns_send_req( TALLOC_CTX *ctx, const char *name, int q_type,
 275                               uint8 **buf, int *resp_length )
 276 {
 277         uint8 *buffer = NULL;
 278         size_t buf_len;
 279         int resp_len = NS_PACKETSZ;
 280         static time_t last_dns_check = 0;
 281         static NTSTATUS last_dns_status = NT_STATUS_OK;
 282         time_t now = time(NULL);
 283
 284         /* Try to prevent bursts of DNS lookups if the server is down */
 285
 286         /* Protect against large clock changes */
 287
 288         if ( last_dns_check > now )
 289                 last_dns_check = 0;
 290
 291         /* IF we had a DNS timeout or a bad server and we are still
 292            in the 30 second cache window, just return the previous
 293            status and save the network timeout. */
 294
 295         if ( (NT_STATUS_EQUAL(last_dns_status,NT_STATUS_IO_TIMEOUT) ||
 296               NT_STATUS_EQUAL(last_dns_status,NT_STATUS_CONNECTION_REFUSED)) &&
 297              (last_dns_check+DNS_FAILED_WAITTIME) > now )
 298         {
 299                 DEBUG(10,("last_dns_check: Returning cached status (%s)\n",
 300                           nt_errstr(last_dns_status) ));
 301                 return last_dns_status;
 302         }
 303
 304         /* Send the Query */
 305         do {
 306                 if ( buffer )
 307                         TALLOC_FREE( buffer );
 308
 309                 buf_len = resp_len * sizeof(uint8);
 310
 311                 if (buf_len) {
 312                         if ( (buffer = TALLOC_ARRAY(ctx, uint8, buf_len)) == NULL ) {
 313                                 DEBUG(0,("ads_dns_lookup_srv: talloc() failed!\n"));
 314                                 last_dns_status = NT_STATUS_NO_MEMORY;
 315                                 last_dns_check = time(NULL);
 316                                 return last_dns_status;
 317                         }
 318                 }
 319
 320                 if ( (resp_len = res_query(name, C_IN, q_type, buffer, buf_len)) < 0 ) {
 321                         DEBUG(3,("ads_dns_lookup_srv: Failed to resolve %s (%s)\n", name, strerror(errno)));
 322                         TALLOC_FREE( buffer );
 323                         last_dns_status = NT_STATUS_UNSUCCESSFUL;
 324
 325                         if (errno == ETIMEDOUT) {
 326                                 last_dns_status = NT_STATUS_IO_TIMEOUT;
 327                         }
 328                         if (errno == ECONNREFUSED) {
 329                                 last_dns_status = NT_STATUS_CONNECTION_REFUSED;
 330                         }
 331                         last_dns_check = time(NULL);
 332                         return last_dns_status;
 333                 }
 334         } while ( buf_len < resp_len && resp_len < MAX_DNS_PACKET_SIZE );
 335
 336         *buf = buffer;
 337         *resp_length = resp_len;
 338
 339         last_dns_check = time(NULL);
 340         last_dns_status = NT_STATUS_OK;
 341         return last_dns_status;
 342 }
 343
 344 /*********************************************************************
 345  Simple wrapper for a DNS SRV query
 346 *********************************************************************/
 347
 348 static NTSTATUS ads_dns_lookup_srv( TALLOC_CTX *ctx, const char *name, struct dns_rr_srv **dclist, int *numdcs )
 349 {
 350         uint8 *buffer = NULL;
 351         int resp_len = 0;
 352         struct dns_rr_srv *dcs = NULL;
 353         int query_count, answer_count, auth_count, additional_count;
 354         uint8 *p = buffer;
 355         int rrnum;
 356         int idx = 0;
 357         NTSTATUS status;
 358
 359         if ( !ctx || !name || !dclist ) {
 360                 return NT_STATUS_INVALID_PARAMETER;
 361         }
 362
 363         /* Send the request.  May have to loop several times in case
 364            of large replies */
 365
 366         status = dns_send_req( ctx, name, T_SRV, &buffer, &resp_len );
 367         if ( !NT_STATUS_IS_OK(status) ) {
 368                 DEBUG(3,("ads_dns_lookup_srv: Failed to send DNS query (%s)\n",
 369                         nt_errstr(status)));
 370                 return status;
 371         }
 372         p = buffer;
 373
 374         /* For some insane reason, the ns_initparse() et. al. routines are only
 375            available in libresolv.a, and not the shared lib.  Who knows why....
 376            So we have to parse the DNS reply ourselves */
 377
 378         /* Pull the answer RR's count from the header.  Use the NMB ordering macros */
 379
 380         query_count      = RSVAL( p, 4 );
 381         answer_count     = RSVAL( p, 6 );
 382         auth_count       = RSVAL( p, 8 );
 383         additional_count = RSVAL( p, 10 );
 384
 385         DEBUG(4,("ads_dns_lookup_srv: %d records returned in the answer section.\n",
 386                 answer_count));
 387
 388         if (answer_count) {
 389                 if ( (dcs = TALLOC_ZERO_ARRAY(ctx, struct dns_rr_srv, answer_count)) == NULL ) {
 390                         DEBUG(0,("ads_dns_lookup_srv: talloc() failure for %d char*'s\n",
 391                                 answer_count));
 392                         return NT_STATUS_NO_MEMORY;
 393                 }
 394         } else {
 395                 dcs = NULL;
 396         }
 397
 398         /* now skip the header */
 399
 400         p += NS_HFIXEDSZ;
 401
 402         /* parse the query section */
 403
 404         for ( rrnum=0; rrnum<query_count; rrnum++ ) {
 405                 struct dns_query q;
 406
 407                 if ( !ads_dns_parse_query( ctx, buffer, buffer+resp_len, &p, &q ) ) {
 408                         DEBUG(1,("ads_dns_lookup_srv: Failed to parse query record!\n"));
 409                         return NT_STATUS_UNSUCCESSFUL;
 410                 }
 411         }
 412
 413         /* now we are at the answer section */
 414
 415         for ( rrnum=0; rrnum<answer_count; rrnum++ ) {
 416                 if ( !ads_dns_parse_rr_srv( ctx, buffer, buffer+resp_len, &p, &dcs[rrnum] ) ) {
 417                         DEBUG(1,("ads_dns_lookup_srv: Failed to parse answer record!\n"));
 418                         return NT_STATUS_UNSUCCESSFUL;
 419                 }
 420         }
 421         idx = rrnum;
 422
 423         /* Parse the authority section */
 424         /* just skip these for now */
 425
 426         for ( rrnum=0; rrnum<auth_count; rrnum++ ) {
 427                 struct dns_rr rr;
 428
 429                 if ( !ads_dns_parse_rr( ctx, buffer, buffer+resp_len, &p, &rr ) ) {
 430                         DEBUG(1,("ads_dns_lookup_srv: Failed to parse authority record!\n"));
 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, &p, &rr ) ) {
 442                         DEBUG(1,("ads_dns_lookup_srv: Failed to parse additional records section!\n"));
 443                         return NT_STATUS_UNSUCCESSFUL;
 444                 }
 445
 446                 /* only interested in A records as a shortcut for having to come
 447                    back later and lookup the name.  For multi-homed hosts, the
 448                    number of additional records and exceed the number of answer
 449                    records. */
 450
 451
 452                 if ( (rr.type != T_A) || (rr.rdatalen != 4) )
 453                         continue;
 454
 455                 for ( i=0; i<idx; i++ ) {
 456                         if ( strcmp( rr.hostname, dcs[i].hostname ) == 0 ) {
 457                                 int num_ips = dcs[i].num_ips;
 458                                 uint8 *buf;
 459                                 struct in_addr *tmp_ips;
 460
 461                                 /* allocate new memory */
 462
 463                                 if ( dcs[i].num_ips == 0 ) {
 464                                         if ( (dcs[i].ips = TALLOC_ARRAY( dcs,
 465                                                 struct in_addr, 1 )) == NULL )
 466                                         {
 467                                                 return NT_STATUS_NO_MEMORY;
 468                                         }
 469                                 } else {
 470                                         if ( (tmp_ips = TALLOC_REALLOC_ARRAY( dcs, dcs[i].ips,
 471                                                 struct in_addr, dcs[i].num_ips+1)) == NULL )
 472                                         {
 473                                                 return NT_STATUS_NO_MEMORY;
 474                                         }
 475
 476                                         dcs[i].ips = tmp_ips;
 477                                 }
 478                                 dcs[i].num_ips++;
 479
 480                                 /* copy the new IP address */
 481
 482                                 buf = (uint8*)&dcs[i].ips[num_ips].s_addr;
 483                                 memcpy( buf, rr.rdata, 4 );
 484                         }
 485                 }
 486         }
 487
 488         qsort( dcs, idx, sizeof(struct dns_rr_srv), QSORT_CAST dnssrvcmp );
 489
 490         *dclist = dcs;
 491         *numdcs = idx;
 492
 493         return NT_STATUS_OK;
 494 }
 495
 496 /*********************************************************************
 497  Simple wrapper for a DNS NS query
 498 *********************************************************************/
 499
 500 NTSTATUS ads_dns_lookup_ns( TALLOC_CTX *ctx, const char *dnsdomain, struct dns_rr_ns **nslist, int *numns )
 501 {
 502         uint8 *buffer = NULL;
 503         int resp_len = 0;
 504         struct dns_rr_ns *nsarray = NULL;
 505         int query_count, answer_count, auth_count, additional_count;
 506         uint8 *p;
 507         int rrnum;
 508         int idx = 0;
 509         NTSTATUS status;
 510
 511         if ( !ctx || !dnsdomain || !nslist ) {
 512                 return NT_STATUS_INVALID_PARAMETER;
 513         }
 514
 515         /* Send the request.  May have to loop several times in case
 516            of large replies */
 517
 518         status = dns_send_req( ctx, dnsdomain, T_NS, &buffer, &resp_len );
 519         if ( !NT_STATUS_IS_OK(status) ) {
 520                 DEBUG(3,("ads_dns_lookup_ns: Failed to send DNS query (%s)\n",
 521                         nt_errstr(status)));
 522                 return status;
 523         }
 524         p = buffer;
 525
 526         /* For some insane reason, the ns_initparse() et. al. routines are only
 527            available in libresolv.a, and not the shared lib.  Who knows why....
 528            So we have to parse the DNS reply ourselves */
 529
 530         /* Pull the answer RR's count from the header.  Use the NMB ordering macros */
 531
 532         query_count      = RSVAL( p, 4 );
 533         answer_count     = RSVAL( p, 6 );
 534         auth_count       = RSVAL( p, 8 );
 535         additional_count = RSVAL( p, 10 );
 536
 537         DEBUG(4,("ads_dns_lookup_ns: %d records returned in the answer section.\n",
 538                 answer_count));
 539
 540         if (answer_count) {
 541                 if ( (nsarray = TALLOC_ARRAY(ctx, struct dns_rr_ns, answer_count)) == NULL ) {
 542                         DEBUG(0,("ads_dns_lookup_ns: talloc() failure for %d char*'s\n",
 543                                 answer_count));
 544                         return NT_STATUS_NO_MEMORY;
 545                 }
 546         } else {
 547                 nsarray = NULL;
 548         }
 549
 550         /* now skip the header */
 551
 552         p += NS_HFIXEDSZ;
 553
 554         /* parse the query section */
 555
 556         for ( rrnum=0; rrnum<query_count; rrnum++ ) {
 557                 struct dns_query q;
 558
 559                 if ( !ads_dns_parse_query( ctx, buffer, buffer+resp_len, &p, &q ) ) {
 560                         DEBUG(1,("ads_dns_lookup_ns: Failed to parse query record!\n"));
 561                         return NT_STATUS_UNSUCCESSFUL;
 562                 }
 563         }
 564
 565         /* now we are at the answer section */
 566
 567         for ( rrnum=0; rrnum<answer_count; rrnum++ ) {
 568                 if ( !ads_dns_parse_rr_ns( ctx, buffer, buffer+resp_len, &p, &nsarray[rrnum] ) ) {
 569                         DEBUG(1,("ads_dns_lookup_ns: Failed to parse answer record!\n"));
 570                         return NT_STATUS_UNSUCCESSFUL;
 571                 }
 572         }
 573         idx = rrnum;
 574
 575         /* Parse the authority section */
 576         /* just skip these for now */
 577
 578         for ( rrnum=0; rrnum<auth_count; rrnum++ ) {
 579                 struct dns_rr rr;
 580
 581                 if ( !ads_dns_parse_rr( ctx, buffer, buffer+resp_len, &p, &rr ) ) {
 582                         DEBUG(1,("ads_dns_lookup_ns: Failed to parse authority record!\n"));
 583                         return NT_STATUS_UNSUCCESSFUL;
 584                 }
 585         }
 586
 587         /* Parse the additional records section */
 588
 589         for ( rrnum=0; rrnum<additional_count; rrnum++ ) {
 590                 struct dns_rr rr;
 591                 int i;
 592
 593                 if ( !ads_dns_parse_rr( ctx, buffer, buffer+resp_len, &p, &rr ) ) {
 594                         DEBUG(1,("ads_dns_lookup_ns: Failed to parse additional records section!\n"));
 595                         return NT_STATUS_UNSUCCESSFUL;
 596                 }
 597
 598                 /* only interested in A records as a shortcut for having to come
 599                    back later and lookup the name */
 600
 601                 if ( (rr.type != T_A) || (rr.rdatalen != 4) )
 602                         continue;
 603
 604                 for ( i=0; i<idx; i++ ) {
 605                         if ( strcmp( rr.hostname, nsarray[i].hostname ) == 0 ) {
 606                                 uint8 *buf = (uint8*)&nsarray[i].ip.s_addr;
 607                                 memcpy( buf, rr.rdata, 4 );
 608                         }
 609                 }
 610         }
 611
 612         *nslist = nsarray;
 613         *numns = idx;
 614
 615         return NT_STATUS_OK;
 616 }
 617
 618 /****************************************************************************
 619  Store and fetch the AD client sitename.
 620 ****************************************************************************/
 621
 622 #define SITENAME_KEY    "AD_SITENAME/DOMAIN/%s"
 623
 624 static char *sitename_key(const char *realm)
 625 {
 626         char *keystr;
 627
 628         if (asprintf(&keystr, SITENAME_KEY, strupper_static(realm)) == -1) {
 629                 return NULL;
 630         }
 631
 632         return keystr;
 633 }
 634
 635
 636 /****************************************************************************
 637  Store the AD client sitename.
 638  We store indefinately as every new CLDAP query will re-write this.
 639 ****************************************************************************/
 640
 641 BOOL sitename_store(const char *realm, const char *sitename)
 642 {
 643         time_t expire;
 644         BOOL ret = False;
 645         char *key;
 646
 647         if (!gencache_init()) {
 648                 return False;
 649         }
 650
 651         if (!realm || (strlen(realm) == 0)) {
 652                 DEBUG(0,("sitename_store: no realm\n"));
 653                 return False;
 654         }
 655
 656         key = sitename_key(realm);
 657
 658         if (!sitename || (sitename && !*sitename)) {
 659                 DEBUG(5,("sitename_store: deleting empty sitename!\n"));
 660                 ret = gencache_del(key);
 661                 SAFE_FREE(key);
 662                 return ret;
 663         }
 664
 665         expire = get_time_t_max(); /* Store indefinately. */
 666
 667         DEBUG(10,("sitename_store: realm = [%s], sitename = [%s], expire = [%u]\n",
 668                 realm, sitename, (unsigned int)expire ));
 669
 670         ret = gencache_set( key, sitename, expire );
 671         SAFE_FREE(key);
 672         return ret;
 673 }
 674
 675 /****************************************************************************
 676  Fetch the AD client sitename.
 677  Caller must free.
 678 ****************************************************************************/
 679
 680 char *sitename_fetch(const char *realm)
 681 {
 682         char *sitename = NULL;
 683         time_t timeout;
 684         BOOL ret = False;
 685         const char *query_realm;
 686         char *key;
 687
 688         if (!gencache_init()) {
 689                 return False;
 690         }
 691
 692         if (!realm || (strlen(realm) == 0)) {
 693                 query_realm = lp_realm();
 694         } else {
 695                 query_realm = realm;
 696         }
 697
 698         key = sitename_key(query_realm);
 699
 700         ret = gencache_get( key, &sitename, &timeout );
 701         SAFE_FREE(key);
 702         if ( !ret ) {
 703                 DEBUG(5,("sitename_fetch: No stored sitename for %s\n",
 704                         query_realm));
 705         } else {
 706                 DEBUG(5,("sitename_fetch: Returning sitename for %s: \"%s\"\n",
 707                         query_realm, sitename ));
 708         }
 709         return sitename;
 710 }
 711
 712 /****************************************************************************
 713  Did the sitename change ?
 714 ****************************************************************************/
 715
 716 BOOL stored_sitename_changed(const char *realm, const char *sitename)
 717 {
 718         BOOL ret = False;
 719
 720         char *new_sitename;
 721
 722         if (!realm || (strlen(realm) == 0)) {
 723                 DEBUG(0,("stored_sitename_changed: no realm\n"));
 724                 return False;
 725         }
 726
 727         new_sitename = sitename_fetch(realm);
 728
 729         if (sitename && new_sitename && !strequal(sitename, new_sitename)) {
 730                 ret = True;
 731         } else if ((sitename && !new_sitename) ||
 732                         (!sitename && new_sitename)) {
 733                 ret = True;
 734         }
 735         SAFE_FREE(new_sitename);
 736         return ret;
 737 }
 738
 739 /********************************************************************
 740  Query with optional sitename.
 741 ********************************************************************/
 742
 743 static NTSTATUS ads_dns_query_internal(TALLOC_CTX *ctx,
 744                                        const char *servicename,
 745                                        const char *dc_pdc_gc_domains,
 746                                        const char *realm,
 747                                        const char *sitename,
 748                                        struct dns_rr_srv **dclist,
 749                                        int *numdcs )
 750 {
 751         char *name;
 752         if (sitename) {
 753                 name = talloc_asprintf(ctx, "%s._tcp.%s._sites.%s._msdcs.%s",
 754                                        servicename, sitename,
 755                                        dc_pdc_gc_domains, realm);
 756         } else {
 757                 name = talloc_asprintf(ctx, "%s._tcp.%s._msdcs.%s",
 758                                 servicename, dc_pdc_gc_domains, 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", "dc", 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 &&
 787             ((!NT_STATUS_IS_OK(status)) ||
 788              (NT_STATUS_IS_OK(status) && (numdcs == 0)))) {
 789                 /* Sitename DNS query may have failed. Try without. */
 790                 status = ads_dns_query_internal(ctx, "_ldap", "dc", realm,
 791                                                 NULL, dclist, numdcs);
 792         }
 793         return status;
 794 }
 795
 796 /********************************************************************
 797  Query for AD GC's.
 798 ********************************************************************/
 799
 800 NTSTATUS ads_dns_query_gcs(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, "_ldap", "gc", 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 &&
 817             ((!NT_STATUS_IS_OK(status)) ||
 818              (NT_STATUS_IS_OK(status) && (numdcs == 0)))) {
 819                 /* Sitename DNS query may have failed. Try without. */
 820                 status = ads_dns_query_internal(ctx, "_ldap", "gc", realm,
 821                                                 NULL, dclist, numdcs);
 822         }
 823         return status;
 824 }
 825
 826 /********************************************************************
 827  Query for AD KDC's.
 828  Even if our underlying kerberos libraries are UDP only, this
 829  is pretty safe as it's unlikely that a KDC supports TCP and not UDP.
 830 ********************************************************************/
 831
 832 NTSTATUS ads_dns_query_kdcs(TALLOC_CTX *ctx,
 833                             const char *dns_forest_name,
 834                             const char *sitename,
 835                             struct dns_rr_srv **dclist,
 836                             int *numdcs )
 837 {
 838         NTSTATUS status;
 839
 840         status = ads_dns_query_internal(ctx, "_kerberos", "dc",
 841                                         dns_forest_name, sitename, dclist,
 842                                         numdcs);
 843
 844         if (NT_STATUS_EQUAL(status, NT_STATUS_IO_TIMEOUT) ||
 845             NT_STATUS_EQUAL(status, NT_STATUS_CONNECTION_REFUSED)) {
 846                 return status;
 847         }
 848
 849         if (sitename &&
 850             ((!NT_STATUS_IS_OK(status)) ||
 851              (NT_STATUS_IS_OK(status) && (numdcs == 0)))) {
 852                 /* Sitename DNS query may have failed. Try without. */
 853                 status = ads_dns_query_internal(ctx, "_kerberos", "dc",
 854                                                 dns_forest_name, NULL,
 855                                                 dclist, numdcs);
 856         }
 857         return status;
 858 }
 859
 860 /********************************************************************
 861  Query for AD PDC. Sitename is obsolete here.
 862 ********************************************************************/
 863
 864 NTSTATUS ads_dns_query_pdc(TALLOC_CTX *ctx,
 865                            const char *dns_domain_name,
 866                            struct dns_rr_srv **dclist,
 867                            int *numdcs )
 868 {
 869         return ads_dns_query_internal(ctx, "_ldap", "pdc", dns_domain_name,
 870                                       NULL, dclist, numdcs);
 871 }
 872
 873 /********************************************************************
 874  Query for AD DC by guid. Sitename is obsolete here.
 875 ********************************************************************/
 876
 877 NTSTATUS ads_dns_query_dcs_guid(TALLOC_CTX *ctx,
 878                                 const char *dns_forest_name,
 879                                 const struct GUID *domain_guid,
 880                                 struct dns_rr_srv **dclist,
 881                                 int *numdcs )
 882 {
 883         /*_ldap._tcp.DomainGuid.domains._msdcs.DnsForestName */
 884
 885         const char *domains;
 886         const char *guid_string;
 887
 888         guid_string = GUID_string(ctx, domain_guid);
 889         if (!guid_string) {
 890                 return NT_STATUS_NO_MEMORY;
 891         }
 892
 893         /* little hack */
 894         domains = talloc_asprintf(ctx, "%s.domains", guid_string);
 895         if (!domains) {
 896                 return NT_STATUS_NO_MEMORY;
 897         }
 898
 899         return ads_dns_query_internal(ctx, "_ldap", domains, dns_forest_name,
 900                                       NULL, dclist, numdcs);
 901 }