08180a65c0ca21b4c1dfda7329403cd3d8f1c169
[samba.git] / source3 / libads / dns.c
1 /*
2    Unix SMB/CIFS implementation.
3    DNS utility library
4    Copyright (C) Gerald (Jerry) Carter           2006.
5    Copyright (C) Jeremy Allison                  2007.
6
7    This program is free software; you can redistribute it and/or modify
8    it under the terms of the GNU General Public License as published by
9    the Free Software Foundation; either version 3 of the License, or
10    (at your option) any later version.
11
12    This program is distributed in the hope that it will be useful,
13    but WITHOUT ANY WARRANTY; without even the implied warranty of
14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15    GNU General Public License for more details.
16
17    You should have received a copy of the GNU General Public License
18    along with this program.  If not, see <http://www.gnu.org/licenses/>.
19 */
20
21 #include "includes.h"
22 #include "libads/dns.h"
23 #include "../librpc/ndr/libndr.h"
24
25 /* AIX resolv.h uses 'class' in struct ns_rr */
26
27 #if defined(AIX)
28 #  if defined(class)
29 #    undef class
30 #  endif
31 #endif  /* AIX */
32
33 /* resolver headers */
34
35 #include <sys/types.h>
36 #include <netinet/in.h>
37 #include <arpa/nameser.h>
38 #include <resolv.h>
39 #include <netdb.h>
40
41 #define MAX_DNS_PACKET_SIZE 0xffff
42
43 #ifdef NS_HFIXEDSZ      /* Bind 8/9 interface */
44 #if !defined(C_IN)      /* AIX 5.3 already defines C_IN */
45 #  define C_IN          ns_c_in
46 #endif
47 #if !defined(T_A)       /* AIX 5.3 already defines T_A */
48 #  define T_A           ns_t_a
49 #endif
50
51 #if defined(HAVE_IPV6)
52 #if !defined(T_AAAA)
53 #  define T_AAAA        ns_t_aaaa
54 #endif
55 #endif
56
57 #  define T_SRV         ns_t_srv
58 #if !defined(T_NS)      /* AIX 5.3 already defines T_NS */
59 #  define T_NS          ns_t_ns
60 #endif
61 #else
62 #  ifdef HFIXEDSZ
63 #    define NS_HFIXEDSZ HFIXEDSZ
64 #  else
65 #    define NS_HFIXEDSZ sizeof(HEADER)
66 #  endif        /* HFIXEDSZ */
67 #  ifdef PACKETSZ
68 #    define NS_PACKETSZ PACKETSZ
69 #  else /* 512 is usually the default */
70 #    define NS_PACKETSZ 512
71 #  endif        /* PACKETSZ */
72 #  define T_SRV         33
73 #endif
74
75 /*********************************************************************
76 *********************************************************************/
77
78 static bool ads_dns_parse_query( TALLOC_CTX *ctx, uint8 *start, uint8 *end,
79                           uint8 **ptr, struct dns_query *q )
80 {
81         uint8 *p = *ptr;
82         char hostname[MAX_DNS_NAME_LENGTH];
83         int namelen;
84
85         ZERO_STRUCTP( q );
86
87         if ( !start || !end || !q || !*ptr)
88                 return False;
89
90         /* See RFC 1035 for details. If this fails, then return. */
91
92         namelen = dn_expand( start, end, p, hostname, sizeof(hostname) );
93         if ( namelen < 0 ) {
94                 return False;
95         }
96         p += namelen;
97         q->hostname = talloc_strdup( ctx, hostname );
98
99         /* check that we have space remaining */
100
101         if ( PTR_DIFF(p+4, end) > 0 )
102                 return False;
103
104         q->type     = RSVAL( p, 0 );
105         q->in_class = RSVAL( p, 2 );
106         p += 4;
107
108         *ptr = p;
109
110         return True;
111 }
112
113 /*********************************************************************
114 *********************************************************************/
115
116 static bool ads_dns_parse_rr( TALLOC_CTX *ctx, uint8 *start, uint8 *end,
117                        uint8 **ptr, struct dns_rr *rr )
118 {
119         uint8 *p = *ptr;
120         char hostname[MAX_DNS_NAME_LENGTH];
121         int namelen;
122
123         if ( !start || !end || !rr || !*ptr)
124                 return -1;
125
126         ZERO_STRUCTP( rr );
127         /* pull the name from the answer */
128
129         namelen = dn_expand( start, end, p, hostname, sizeof(hostname) );
130         if ( namelen < 0 ) {
131                 return -1;
132         }
133         p += namelen;
134         rr->hostname = talloc_strdup( ctx, hostname );
135
136         /* check that we have space remaining */
137
138         if ( PTR_DIFF(p+10, end) > 0 )
139                 return False;
140
141         /* pull some values and then skip onto the string */
142
143         rr->type     = RSVAL(p, 0);
144         rr->in_class = RSVAL(p, 2);
145         rr->ttl      = RIVAL(p, 4);
146         rr->rdatalen = RSVAL(p, 8);
147
148         p += 10;
149
150         /* sanity check the available space */
151
152         if ( PTR_DIFF(p+rr->rdatalen, end ) > 0 ) {
153                 return False;
154
155         }
156
157         /* save a point to the rdata for this section */
158
159         rr->rdata = p;
160         p += rr->rdatalen;
161
162         *ptr = p;
163
164         return True;
165 }
166
167 /*********************************************************************
168 *********************************************************************/
169
170 static bool ads_dns_parse_rr_srv( TALLOC_CTX *ctx, uint8 *start, uint8 *end,
171                        uint8 **ptr, struct dns_rr_srv *srv )
172 {
173         struct dns_rr rr;
174         uint8 *p;
175         char dcname[MAX_DNS_NAME_LENGTH];
176         int namelen;
177
178         if ( !start || !end || !srv || !*ptr)
179                 return -1;
180
181         /* Parse the RR entry.  Coming out of the this, ptr is at the beginning
182            of the next record */
183
184         if ( !ads_dns_parse_rr( ctx, start, end, ptr, &rr ) ) {
185                 DEBUG(1,("ads_dns_parse_rr_srv: Failed to parse RR record\n"));
186                 return False;
187         }
188
189         if ( rr.type != T_SRV ) {
190                 DEBUG(1,("ads_dns_parse_rr_srv: Bad answer type (%d)\n",
191                                         rr.type));
192                 return False;
193         }
194
195         p = rr.rdata;
196
197         srv->priority = RSVAL(p, 0);
198         srv->weight   = RSVAL(p, 2);
199         srv->port     = RSVAL(p, 4);
200
201         p += 6;
202
203         namelen = dn_expand( start, end, p, dcname, sizeof(dcname) );
204         if ( namelen < 0 ) {
205                 DEBUG(1,("ads_dns_parse_rr_srv: Failed to uncompress name!\n"));
206                 return False;
207         }
208
209         srv->hostname = talloc_strdup( ctx, dcname );
210
211         DEBUG(10,("ads_dns_parse_rr_srv: Parsed %s [%u, %u, %u]\n", 
212                   srv->hostname, 
213                   srv->priority,
214                   srv->weight,
215                   srv->port));
216
217         return True;
218 }
219
220 /*********************************************************************
221 *********************************************************************/
222
223 static bool ads_dns_parse_rr_ns( TALLOC_CTX *ctx, uint8 *start, uint8 *end,
224                        uint8 **ptr, struct dns_rr_ns *nsrec )
225 {
226         struct dns_rr rr;
227         uint8 *p;
228         char nsname[MAX_DNS_NAME_LENGTH];
229         int namelen;
230
231         if ( !start || !end || !nsrec || !*ptr)
232                 return -1;
233
234         /* Parse the RR entry.  Coming out of the this, ptr is at the beginning
235            of the next record */
236
237         if ( !ads_dns_parse_rr( ctx, start, end, ptr, &rr ) ) {
238                 DEBUG(1,("ads_dns_parse_rr_ns: Failed to parse RR record\n"));
239                 return False;
240         }
241
242         if ( rr.type != T_NS ) {
243                 DEBUG(1,("ads_dns_parse_rr_ns: Bad answer type (%d)\n",
244                                         rr.type));
245                 return False;
246         }
247
248         p = rr.rdata;
249
250         /* ame server hostname */
251
252         namelen = dn_expand( start, end, p, nsname, sizeof(nsname) );
253         if ( namelen < 0 ) {
254                 DEBUG(1,("ads_dns_parse_rr_ns: Failed to uncompress name!\n"));
255                 return False;
256         }
257         nsrec->hostname = talloc_strdup( ctx, nsname );
258
259         return True;
260 }
261
262 /*********************************************************************
263  Sort SRV record list based on weight and priority.  See RFC 2782.
264 *********************************************************************/
265
266 static int dnssrvcmp( struct dns_rr_srv *a, struct dns_rr_srv *b )
267 {
268         if ( a->priority == b->priority ) {
269
270                 /* randomize entries with an equal weight and priority */
271                 if ( a->weight == b->weight )
272                         return 0;
273
274                 /* higher weights should be sorted lower */
275                 if ( a->weight > b->weight )
276                         return -1;
277                 else
278                         return 1;
279         }
280
281         if ( a->priority < b->priority )
282                 return -1;
283
284         return 1;
285 }
286
287 /*********************************************************************
288  Simple wrapper for a DNS query
289 *********************************************************************/
290
291 #define DNS_FAILED_WAITTIME          30
292
293 static NTSTATUS dns_send_req( TALLOC_CTX *ctx, const char *name, int q_type,
294                               uint8 **buf, int *resp_length )
295 {
296         uint8 *buffer = NULL;
297         size_t buf_len = 0;
298         int resp_len = NS_PACKETSZ;
299         static time_t last_dns_check = 0;
300         static NTSTATUS last_dns_status = NT_STATUS_OK;
301         time_t now = time_mono(NULL);
302
303         /* Try to prevent bursts of DNS lookups if the server is down */
304
305         /* Protect against large clock changes */
306
307         if ( last_dns_check > now )
308                 last_dns_check = 0;
309
310         /* IF we had a DNS timeout or a bad server and we are still
311            in the 30 second cache window, just return the previous
312            status and save the network timeout. */
313
314         if ( (NT_STATUS_EQUAL(last_dns_status,NT_STATUS_IO_TIMEOUT) ||
315               NT_STATUS_EQUAL(last_dns_status,NT_STATUS_CONNECTION_REFUSED)) &&
316              (last_dns_check+DNS_FAILED_WAITTIME) > now )
317         {
318                 DEBUG(10,("last_dns_check: Returning cached status (%s)\n",
319                           nt_errstr(last_dns_status) ));
320                 return last_dns_status;
321         }
322
323         /* Send the Query */
324         do {
325                 if ( buffer )
326                         TALLOC_FREE( buffer );
327
328                 buf_len = resp_len * sizeof(uint8);
329
330                 if (buf_len) {
331                         if ((buffer = TALLOC_ARRAY(ctx, uint8, buf_len))
332                                         == NULL ) {
333                                 DEBUG(0,("ads_dns_lookup_srv: "
334                                         "talloc() failed!\n"));
335                                 last_dns_status = NT_STATUS_NO_MEMORY;
336                                 last_dns_check = time_mono(NULL);
337                                 return last_dns_status;
338                         }
339                 }
340
341                 if ((resp_len = res_query(name, C_IN, q_type, buffer, buf_len))
342                                 < 0 ) {
343                         DEBUG(3,("ads_dns_lookup_srv: "
344                                 "Failed to resolve %s (%s)\n",
345                                 name, strerror(errno)));
346                         TALLOC_FREE( buffer );
347                         last_dns_status = NT_STATUS_UNSUCCESSFUL;
348
349                         if (errno == ETIMEDOUT) {
350                                 last_dns_status = NT_STATUS_IO_TIMEOUT;
351                         }
352                         if (errno == ECONNREFUSED) {
353                                 last_dns_status = NT_STATUS_CONNECTION_REFUSED;
354                         }
355                         last_dns_check = time_mono(NULL);
356                         return last_dns_status;
357                 }
358
359                 /* On AIX, Solaris, and possibly some older glibc systems (e.g. SLES8)
360                    truncated replies never give back a resp_len > buflen
361                    which ends up causing DNS resolve failures on large tcp DNS replies */
362
363                 if (buf_len == resp_len) {
364                         if (resp_len == MAX_DNS_PACKET_SIZE) {
365                                 DEBUG(1,("dns_send_req: DNS reply too large when resolving %s\n",
366                                         name));
367                                 TALLOC_FREE( buffer );
368                                 last_dns_status = NT_STATUS_BUFFER_TOO_SMALL;
369                                 last_dns_check = time_mono(NULL);
370                                 return last_dns_status;
371                         }
372
373                         resp_len = MIN(resp_len*2, MAX_DNS_PACKET_SIZE);
374                 }
375
376
377         } while ( buf_len < resp_len && resp_len <= MAX_DNS_PACKET_SIZE );
378
379         *buf = buffer;
380         *resp_length = resp_len;
381
382         last_dns_check = time_mono(NULL);
383         last_dns_status = NT_STATUS_OK;
384         return last_dns_status;
385 }
386
387 /*********************************************************************
388  Simple wrapper for a DNS SRV query
389 *********************************************************************/
390
391 static NTSTATUS ads_dns_lookup_srv( TALLOC_CTX *ctx,
392                                 const char *name,
393                                 struct dns_rr_srv **dclist,
394                                 int *numdcs)
395 {
396         uint8 *buffer = NULL;
397         int resp_len = 0;
398         struct dns_rr_srv *dcs = NULL;
399         int query_count, answer_count, auth_count, additional_count;
400         uint8 *p = buffer;
401         int rrnum;
402         int idx = 0;
403         NTSTATUS status;
404         const char *dns_hosts_file;
405
406         if ( !ctx || !name || !dclist ) {
407                 return NT_STATUS_INVALID_PARAMETER;
408         }
409
410         dns_hosts_file = lp_parm_const_string(-1, "resolv", "host file", NULL);
411         if (dns_hosts_file) {
412                 return resolve_dns_hosts_file_as_dns_rr(dns_hosts_file,
413                                                         name, true, ctx,
414                                                         dclist, numdcs);
415         }
416
417         /* Send the request.  May have to loop several times in case
418            of large replies */
419
420         status = dns_send_req( ctx, name, T_SRV, &buffer, &resp_len );
421         if ( !NT_STATUS_IS_OK(status) ) {
422                 DEBUG(3,("ads_dns_lookup_srv: Failed to send DNS query (%s)\n",
423                         nt_errstr(status)));
424                 return status;
425         }
426         p = buffer;
427
428         /* For some insane reason, the ns_initparse() et. al. routines are only
429            available in libresolv.a, and not the shared lib.  Who knows why....
430            So we have to parse the DNS reply ourselves */
431
432         /* Pull the answer RR's count from the header.
433          * Use the NMB ordering macros */
434
435         query_count      = RSVAL( p, 4 );
436         answer_count     = RSVAL( p, 6 );
437         auth_count       = RSVAL( p, 8 );
438         additional_count = RSVAL( p, 10 );
439
440         DEBUG(4,("ads_dns_lookup_srv: "
441                 "%d records returned in the answer section.\n",
442                 answer_count));
443
444         if (answer_count) {
445                 if ((dcs = TALLOC_ZERO_ARRAY(ctx, struct dns_rr_srv,
446                                                 answer_count)) == NULL ) {
447                         DEBUG(0,("ads_dns_lookup_srv: "
448                                 "talloc() failure for %d char*'s\n",
449                                 answer_count));
450                         return NT_STATUS_NO_MEMORY;
451                 }
452         } else {
453                 dcs = NULL;
454         }
455
456         /* now skip the header */
457
458         p += NS_HFIXEDSZ;
459
460         /* parse the query section */
461
462         for ( rrnum=0; rrnum<query_count; rrnum++ ) {
463                 struct dns_query q;
464
465                 if (!ads_dns_parse_query(ctx, buffer,
466                                         buffer+resp_len, &p, &q)) {
467                         DEBUG(1,("ads_dns_lookup_srv: "
468                                  "Failed to parse query record [%d]!\n", rrnum));
469                         return NT_STATUS_UNSUCCESSFUL;
470                 }
471         }
472
473         /* now we are at the answer section */
474
475         for ( rrnum=0; rrnum<answer_count; rrnum++ ) {
476                 if (!ads_dns_parse_rr_srv(ctx, buffer, buffer+resp_len,
477                                         &p, &dcs[rrnum])) {
478                         DEBUG(1,("ads_dns_lookup_srv: "
479                                  "Failed to parse answer recordi [%d]!\n", rrnum));
480                         return NT_STATUS_UNSUCCESSFUL;
481                 }
482         }
483         idx = rrnum;
484
485         /* Parse the authority section */
486         /* just skip these for now */
487
488         for ( rrnum=0; rrnum<auth_count; rrnum++ ) {
489                 struct dns_rr rr;
490
491                 if (!ads_dns_parse_rr( ctx, buffer,
492                                         buffer+resp_len, &p, &rr)) {
493                         DEBUG(1,("ads_dns_lookup_srv: "
494                                  "Failed to parse authority record! [%d]\n", rrnum));
495                         return NT_STATUS_UNSUCCESSFUL;
496                 }
497         }
498
499         /* Parse the additional records section */
500
501         for ( rrnum=0; rrnum<additional_count; rrnum++ ) {
502                 struct dns_rr rr;
503                 int i;
504
505                 if (!ads_dns_parse_rr(ctx, buffer, buffer+resp_len,
506                                         &p, &rr)) {
507                         DEBUG(1,("ads_dns_lookup_srv: Failed "
508                                  "to parse additional records section! [%d]\n", rrnum));
509                         return NT_STATUS_UNSUCCESSFUL;
510                 }
511
512                 /* Only interested in A or AAAA records as a shortcut for having
513                  * to come back later and lookup the name. For multi-homed
514                  * hosts, the number of additional records and exceed the
515                  * number of answer records. */
516
517                 if (rr.type != T_A || rr.rdatalen != 4) {
518 #if defined(HAVE_IPV6)
519                         /* RFC2874 defines A6 records. This
520                          * requires recusive and horribly complex lookups.
521                          * Bastards. Ignore this for now.... JRA.
522                          * Luckily RFC3363 reprecates A6 records.
523                          */
524                         if (rr.type != T_AAAA || rr.rdatalen != 16)
525 #endif
526                                 continue;
527                 }
528
529                 for ( i=0; i<idx; i++ ) {
530                         if ( strcmp( rr.hostname, dcs[i].hostname ) == 0 ) {
531                                 int num_ips = dcs[i].num_ips;
532                                 struct sockaddr_storage *tmp_ss_s;
533
534                                 /* allocate new memory */
535
536                                 if (dcs[i].num_ips == 0) {
537                                         if ((dcs[i].ss_s = TALLOC_ARRAY(dcs,
538                                                 struct sockaddr_storage, 1 ))
539                                                         == NULL ) {
540                                                 return NT_STATUS_NO_MEMORY;
541                                         }
542                                 } else {
543                                         if ((tmp_ss_s = talloc_realloc(dcs,
544                                                         dcs[i].ss_s,
545                                                         struct sockaddr_storage,
546                                                         dcs[i].num_ips+1))
547                                                                 == NULL ) {
548                                                 return NT_STATUS_NO_MEMORY;
549                                         }
550
551                                         dcs[i].ss_s = tmp_ss_s;
552                                 }
553                                 dcs[i].num_ips++;
554
555                                 /* copy the new IP address */
556                                 if (rr.type == T_A) {
557                                         struct in_addr ip;
558                                         memcpy(&ip, rr.rdata, 4);
559                                         in_addr_to_sockaddr_storage(
560                                                         &dcs[i].ss_s[num_ips],
561                                                         ip);
562                                 }
563 #if defined(HAVE_IPV6)
564                                 if (rr.type == T_AAAA) {
565                                         struct in6_addr ip6;
566                                         memcpy(&ip6, rr.rdata, rr.rdatalen);
567                                         in6_addr_to_sockaddr_storage(
568                                                         &dcs[i].ss_s[num_ips],
569                                                         ip6);
570                                 }
571 #endif
572                         }
573                 }
574         }
575
576         TYPESAFE_QSORT(dcs, idx, dnssrvcmp );
577
578         *dclist = dcs;
579         *numdcs = idx;
580
581         return NT_STATUS_OK;
582 }
583
584 /*********************************************************************
585  Simple wrapper for a DNS NS query
586 *********************************************************************/
587
588 NTSTATUS ads_dns_lookup_ns(TALLOC_CTX *ctx,
589                                 const char *dnsdomain,
590                                 struct dns_rr_ns **nslist,
591                                 int *numns)
592 {
593         uint8 *buffer = NULL;
594         int resp_len = 0;
595         struct dns_rr_ns *nsarray = NULL;
596         int query_count, answer_count, auth_count, additional_count;
597         uint8 *p;
598         int rrnum;
599         int idx = 0;
600         NTSTATUS status;
601         const char *dns_hosts_file;
602
603         if ( !ctx || !dnsdomain || !nslist ) {
604                 return NT_STATUS_INVALID_PARAMETER;
605         }
606
607         dns_hosts_file = lp_parm_const_string(-1, "resolv", "host file", NULL);
608         if (dns_hosts_file) {
609                 DEBUG(1, ("NO 'NS' lookup available when using resolv:host file"));
610                 return NT_STATUS_OBJECT_NAME_NOT_FOUND;
611         }
612
613         /* Send the request.  May have to loop several times in case
614            of large replies */
615
616         status = dns_send_req( ctx, dnsdomain, T_NS, &buffer, &resp_len );
617         if ( !NT_STATUS_IS_OK(status) ) {
618                 DEBUG(3,("ads_dns_lookup_ns: Failed to send DNS query (%s)\n",
619                         nt_errstr(status)));
620                 return status;
621         }
622         p = buffer;
623
624         /* For some insane reason, the ns_initparse() et. al. routines are only
625            available in libresolv.a, and not the shared lib.  Who knows why....
626            So we have to parse the DNS reply ourselves */
627
628         /* Pull the answer RR's count from the header.
629          * Use the NMB ordering macros */
630
631         query_count      = RSVAL( p, 4 );
632         answer_count     = RSVAL( p, 6 );
633         auth_count       = RSVAL( p, 8 );
634         additional_count = RSVAL( p, 10 );
635
636         DEBUG(4,("ads_dns_lookup_ns: "
637                 "%d records returned in the answer section.\n",
638                 answer_count));
639
640         if (answer_count) {
641                 if ((nsarray = TALLOC_ARRAY(ctx, struct dns_rr_ns,
642                                                 answer_count)) == NULL ) {
643                         DEBUG(0,("ads_dns_lookup_ns: "
644                                 "talloc() failure for %d char*'s\n",
645                                 answer_count));
646                         return NT_STATUS_NO_MEMORY;
647                 }
648         } else {
649                 nsarray = NULL;
650         }
651
652         /* now skip the header */
653
654         p += NS_HFIXEDSZ;
655
656         /* parse the query section */
657
658         for ( rrnum=0; rrnum<query_count; rrnum++ ) {
659                 struct dns_query q;
660
661                 if (!ads_dns_parse_query(ctx, buffer, buffer+resp_len,
662                                         &p, &q)) {
663                         DEBUG(1,("ads_dns_lookup_ns: "
664                                 " Failed to parse query record!\n"));
665                         return NT_STATUS_UNSUCCESSFUL;
666                 }
667         }
668
669         /* now we are at the answer section */
670
671         for ( rrnum=0; rrnum<answer_count; rrnum++ ) {
672                 if (!ads_dns_parse_rr_ns(ctx, buffer, buffer+resp_len,
673                                         &p, &nsarray[rrnum])) {
674                         DEBUG(1,("ads_dns_lookup_ns: "
675                                 "Failed to parse answer record!\n"));
676                         return NT_STATUS_UNSUCCESSFUL;
677                 }
678         }
679         idx = rrnum;
680
681         /* Parse the authority section */
682         /* just skip these for now */
683
684         for ( rrnum=0; rrnum<auth_count; rrnum++ ) {
685                 struct dns_rr rr;
686
687                 if ( !ads_dns_parse_rr(ctx, buffer, buffer+resp_len,
688                                         &p, &rr)) {
689                         DEBUG(1,("ads_dns_lookup_ns: "
690                                 "Failed to parse authority record!\n"));
691                         return NT_STATUS_UNSUCCESSFUL;
692                 }
693         }
694
695         /* Parse the additional records section */
696
697         for ( rrnum=0; rrnum<additional_count; rrnum++ ) {
698                 struct dns_rr rr;
699                 int i;
700
701                 if (!ads_dns_parse_rr(ctx, buffer, buffer+resp_len,
702                                         &p, &rr)) {
703                         DEBUG(1,("ads_dns_lookup_ns: Failed "
704                                 "to parse additional records section!\n"));
705                         return NT_STATUS_UNSUCCESSFUL;
706                 }
707
708                 /* only interested in A records as a shortcut for having to come
709                    back later and lookup the name */
710
711                 if (rr.type != T_A || rr.rdatalen != 4) {
712 #if defined(HAVE_IPV6)
713                         if (rr.type != T_AAAA || rr.rdatalen != 16)
714 #endif
715                                 continue;
716                 }
717
718                 for ( i=0; i<idx; i++ ) {
719                         if (strcmp(rr.hostname, nsarray[i].hostname) == 0) {
720                                 if (rr.type == T_A) {
721                                         struct in_addr ip;
722                                         memcpy(&ip, rr.rdata, 4);
723                                         in_addr_to_sockaddr_storage(
724                                                         &nsarray[i].ss,
725                                                         ip);
726                                 }
727 #if defined(HAVE_IPV6)
728                                 if (rr.type == T_AAAA) {
729                                         struct in6_addr ip6;
730                                         memcpy(&ip6, rr.rdata, rr.rdatalen);
731                                         in6_addr_to_sockaddr_storage(
732                                                         &nsarray[i].ss,
733                                                         ip6);
734                                 }
735 #endif
736                         }
737                 }
738         }
739
740         *nslist = nsarray;
741         *numns = idx;
742
743         return NT_STATUS_OK;
744 }
745
746 /********************************************************************
747  Query with optional sitename.
748 ********************************************************************/
749
750 static NTSTATUS ads_dns_query_internal(TALLOC_CTX *ctx,
751                                        const char *servicename,
752                                        const char *dc_pdc_gc_domains,
753                                        const char *realm,
754                                        const char *sitename,
755                                        struct dns_rr_srv **dclist,
756                                        int *numdcs )
757 {
758         char *name;
759         if (sitename) {
760                 name = talloc_asprintf(ctx, "%s._tcp.%s._sites.%s._msdcs.%s",
761                                        servicename, sitename,
762                                        dc_pdc_gc_domains, realm);
763         } else {
764                 name = talloc_asprintf(ctx, "%s._tcp.%s._msdcs.%s",
765                                 servicename, dc_pdc_gc_domains, realm);
766         }
767         if (!name) {
768                 return NT_STATUS_NO_MEMORY;
769         }
770         return ads_dns_lookup_srv( ctx, name, dclist, numdcs );
771 }
772
773 /********************************************************************
774  Query for AD DC's.
775 ********************************************************************/
776
777 NTSTATUS ads_dns_query_dcs(TALLOC_CTX *ctx,
778                            const char *realm,
779                            const char *sitename,
780                            struct dns_rr_srv **dclist,
781                            int *numdcs )
782 {
783         NTSTATUS status;
784
785         status = ads_dns_query_internal(ctx, "_ldap", "dc", realm, sitename,
786                                         dclist, numdcs);
787
788         if (NT_STATUS_EQUAL(status, NT_STATUS_IO_TIMEOUT) ||
789             NT_STATUS_EQUAL(status, NT_STATUS_CONNECTION_REFUSED)) {
790                 return status;
791         }
792
793         if (sitename &&
794             ((!NT_STATUS_IS_OK(status)) ||
795              (NT_STATUS_IS_OK(status) && (numdcs == 0)))) {
796                 /* Sitename DNS query may have failed. Try without. */
797                 status = ads_dns_query_internal(ctx, "_ldap", "dc", realm,
798                                                 NULL, dclist, numdcs);
799         }
800         return status;
801 }
802
803 /********************************************************************
804  Query for AD GC's.
805 ********************************************************************/
806
807 NTSTATUS ads_dns_query_gcs(TALLOC_CTX *ctx,
808                            const char *realm,
809                            const char *sitename,
810                            struct dns_rr_srv **dclist,
811                            int *numdcs )
812 {
813         NTSTATUS status;
814
815         status = ads_dns_query_internal(ctx, "_ldap", "gc", realm, sitename,
816                                         dclist, numdcs);
817
818         if (NT_STATUS_EQUAL(status, NT_STATUS_IO_TIMEOUT) ||
819             NT_STATUS_EQUAL(status, NT_STATUS_CONNECTION_REFUSED)) {
820                 return status;
821         }
822
823         if (sitename &&
824             ((!NT_STATUS_IS_OK(status)) ||
825              (NT_STATUS_IS_OK(status) && (numdcs == 0)))) {
826                 /* Sitename DNS query may have failed. Try without. */
827                 status = ads_dns_query_internal(ctx, "_ldap", "gc", realm,
828                                                 NULL, dclist, numdcs);
829         }
830         return status;
831 }
832
833 /********************************************************************
834  Query for AD KDC's.
835  Even if our underlying kerberos libraries are UDP only, this
836  is pretty safe as it's unlikely that a KDC supports TCP and not UDP.
837 ********************************************************************/
838
839 NTSTATUS ads_dns_query_kdcs(TALLOC_CTX *ctx,
840                             const char *dns_forest_name,
841                             const char *sitename,
842                             struct dns_rr_srv **dclist,
843                             int *numdcs )
844 {
845         NTSTATUS status;
846
847         status = ads_dns_query_internal(ctx, "_kerberos", "dc",
848                                         dns_forest_name, sitename, dclist,
849                                         numdcs);
850
851         if (NT_STATUS_EQUAL(status, NT_STATUS_IO_TIMEOUT) ||
852             NT_STATUS_EQUAL(status, NT_STATUS_CONNECTION_REFUSED)) {
853                 return status;
854         }
855
856         if (sitename &&
857             ((!NT_STATUS_IS_OK(status)) ||
858              (NT_STATUS_IS_OK(status) && (numdcs == 0)))) {
859                 /* Sitename DNS query may have failed. Try without. */
860                 status = ads_dns_query_internal(ctx, "_kerberos", "dc",
861                                                 dns_forest_name, NULL,
862                                                 dclist, numdcs);
863         }
864         return status;
865 }
866
867 /********************************************************************
868  Query for AD PDC. Sitename is obsolete here.
869 ********************************************************************/
870
871 NTSTATUS ads_dns_query_pdc(TALLOC_CTX *ctx,
872                            const char *dns_domain_name,
873                            struct dns_rr_srv **dclist,
874                            int *numdcs )
875 {
876         return ads_dns_query_internal(ctx, "_ldap", "pdc", dns_domain_name,
877                                       NULL, dclist, numdcs);
878 }
879
880 /********************************************************************
881  Query for AD DC by guid. Sitename is obsolete here.
882 ********************************************************************/
883
884 NTSTATUS ads_dns_query_dcs_guid(TALLOC_CTX *ctx,
885                                 const char *dns_forest_name,
886                                 const struct GUID *domain_guid,
887                                 struct dns_rr_srv **dclist,
888                                 int *numdcs )
889 {
890         /*_ldap._tcp.DomainGuid.domains._msdcs.DnsForestName */
891
892         const char *domains;
893         char *guid_string;
894
895         guid_string = GUID_string(ctx, domain_guid);
896         if (!guid_string) {
897                 return NT_STATUS_NO_MEMORY;
898         }
899
900         /* little hack */
901         domains = talloc_asprintf(ctx, "%s.domains", guid_string);
902         if (!domains) {
903                 return NT_STATUS_NO_MEMORY;
904         }
905         TALLOC_FREE(guid_string);
906
907         return ads_dns_query_internal(ctx, "_ldap", domains, dns_forest_name,
908                                       NULL, dclist, numdcs);
909 }