2 Unix SMB/CIFS implementation.
4 Copyright (C) Gerald (Jerry) Carter 2006.
5 Copyright (C) Jeremy Allison 2007.
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.
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.
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/>.
22 #include "libads/dns.h"
23 #include "../librpc/ndr/libndr.h"
25 /* AIX resolv.h uses 'class' in struct ns_rr */
33 /* resolver headers */
35 #include <sys/types.h>
36 #include <netinet/in.h>
37 #include <arpa/nameser.h>
41 #define MAX_DNS_PACKET_SIZE 0xffff
43 #ifdef NS_HFIXEDSZ /* Bind 8/9 interface */
44 #if !defined(C_IN) /* AIX 5.3 already defines C_IN */
47 #if !defined(T_A) /* AIX 5.3 already defines T_A */
51 #if defined(HAVE_IPV6)
53 # define T_AAAA ns_t_aaaa
57 # define T_SRV ns_t_srv
58 #if !defined(T_NS) /* AIX 5.3 already defines T_NS */
63 # define NS_HFIXEDSZ HFIXEDSZ
65 # define NS_HFIXEDSZ sizeof(HEADER)
66 # endif /* HFIXEDSZ */
68 # define NS_PACKETSZ PACKETSZ
69 # else /* 512 is usually the default */
70 # define NS_PACKETSZ 512
71 # endif /* PACKETSZ */
75 /*********************************************************************
76 *********************************************************************/
78 static bool ads_dns_parse_query( TALLOC_CTX *ctx, uint8_t *start, uint8_t *end,
79 uint8_t **ptr, struct dns_query *q )
82 char hostname[MAX_DNS_NAME_LENGTH];
87 if ( !start || !end || !q || !*ptr)
90 /* See RFC 1035 for details. If this fails, then return. */
92 namelen = dn_expand( start, end, p, hostname, sizeof(hostname) );
97 q->hostname = talloc_strdup( ctx, hostname );
99 /* check that we have space remaining */
101 if ( PTR_DIFF(p+4, end) > 0 )
104 q->type = RSVAL( p, 0 );
105 q->in_class = RSVAL( p, 2 );
113 /*********************************************************************
114 *********************************************************************/
116 static bool ads_dns_parse_rr( TALLOC_CTX *ctx, uint8_t *start, uint8_t *end,
117 uint8_t **ptr, struct dns_rr *rr )
120 char hostname[MAX_DNS_NAME_LENGTH];
123 if ( !start || !end || !rr || !*ptr)
127 /* pull the name from the answer */
129 namelen = dn_expand( start, end, p, hostname, sizeof(hostname) );
134 rr->hostname = talloc_strdup( ctx, hostname );
136 /* check that we have space remaining */
138 if ( PTR_DIFF(p+10, end) > 0 )
141 /* pull some values and then skip onto the string */
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);
150 /* sanity check the available space */
152 if ( PTR_DIFF(p+rr->rdatalen, end ) > 0 ) {
157 /* save a point to the rdata for this section */
167 /*********************************************************************
168 *********************************************************************/
170 static bool ads_dns_parse_rr_srv( TALLOC_CTX *ctx, uint8_t *start, uint8_t *end,
171 uint8_t **ptr, struct dns_rr_srv *srv )
175 char dcname[MAX_DNS_NAME_LENGTH];
178 if ( !start || !end || !srv || !*ptr)
181 /* Parse the RR entry. Coming out of the this, ptr is at the beginning
182 of the next record */
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"));
189 if ( rr.type != T_SRV ) {
190 DEBUG(1,("ads_dns_parse_rr_srv: Bad answer type (%d)\n",
197 srv->priority = RSVAL(p, 0);
198 srv->weight = RSVAL(p, 2);
199 srv->port = RSVAL(p, 4);
203 namelen = dn_expand( start, end, p, dcname, sizeof(dcname) );
205 DEBUG(1,("ads_dns_parse_rr_srv: Failed to uncompress name!\n"));
209 srv->hostname = talloc_strdup( ctx, dcname );
211 DEBUG(10,("ads_dns_parse_rr_srv: Parsed %s [%u, %u, %u]\n",
220 /*********************************************************************
221 *********************************************************************/
223 static bool ads_dns_parse_rr_ns( TALLOC_CTX *ctx, uint8_t *start, uint8_t *end,
224 uint8_t **ptr, struct dns_rr_ns *nsrec )
228 char nsname[MAX_DNS_NAME_LENGTH];
231 if ( !start || !end || !nsrec || !*ptr)
234 /* Parse the RR entry. Coming out of the this, ptr is at the beginning
235 of the next record */
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"));
242 if ( rr.type != T_NS ) {
243 DEBUG(1,("ads_dns_parse_rr_ns: Bad answer type (%d)\n",
250 /* ame server hostname */
252 namelen = dn_expand( start, end, p, nsname, sizeof(nsname) );
254 DEBUG(1,("ads_dns_parse_rr_ns: Failed to uncompress name!\n"));
257 nsrec->hostname = talloc_strdup( ctx, nsname );
262 /*********************************************************************
263 Sort SRV record list based on weight and priority. See RFC 2782.
264 *********************************************************************/
266 static int dnssrvcmp( struct dns_rr_srv *a, struct dns_rr_srv *b )
268 if ( a->priority == b->priority ) {
270 /* randomize entries with an equal weight and priority */
271 if ( a->weight == b->weight )
274 /* higher weights should be sorted lower */
275 if ( a->weight > b->weight )
281 if ( a->priority < b->priority )
287 /*********************************************************************
288 Simple wrapper for a DNS query
289 *********************************************************************/
291 #define DNS_FAILED_WAITTIME 30
293 static NTSTATUS dns_send_req( TALLOC_CTX *ctx, const char *name, int q_type,
294 uint8_t **buf, int *resp_length )
296 uint8_t *buffer = NULL;
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);
303 /* Try to prevent bursts of DNS lookups if the server is down */
305 /* Protect against large clock changes */
307 if ( last_dns_check > now )
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. */
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 )
318 DEBUG(10,("last_dns_check: Returning cached status (%s)\n",
319 nt_errstr(last_dns_status) ));
320 return last_dns_status;
326 TALLOC_FREE( buffer );
328 buf_len = resp_len * sizeof(uint8_t);
331 if ((buffer = talloc_array(ctx, uint8_t, buf_len))
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;
341 if ((resp_len = res_query(name, C_IN, q_type, buffer, buf_len))
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;
349 if (errno == ETIMEDOUT) {
350 last_dns_status = NT_STATUS_IO_TIMEOUT;
352 if (errno == ECONNREFUSED) {
353 last_dns_status = NT_STATUS_CONNECTION_REFUSED;
355 last_dns_check = time_mono(NULL);
356 return last_dns_status;
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 */
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",
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;
373 resp_len = MIN(resp_len*2, MAX_DNS_PACKET_SIZE);
377 } while ( buf_len < resp_len && resp_len <= MAX_DNS_PACKET_SIZE );
380 *resp_length = resp_len;
382 last_dns_check = time_mono(NULL);
383 last_dns_status = NT_STATUS_OK;
384 return last_dns_status;
387 /*********************************************************************
388 Simple wrapper for a DNS SRV query
389 *********************************************************************/
391 static NTSTATUS ads_dns_lookup_srv( TALLOC_CTX *ctx,
392 const char *dns_hosts_file,
394 struct dns_rr_srv **dclist,
397 uint8_t *buffer = NULL;
399 struct dns_rr_srv *dcs = NULL;
400 int query_count, answer_count, auth_count, additional_count;
406 if ( !ctx || !name || !dclist ) {
407 return NT_STATUS_INVALID_PARAMETER;
410 if (dns_hosts_file) {
411 return resolve_dns_hosts_file_as_dns_rr(dns_hosts_file,
416 /* Send the request. May have to loop several times in case
419 status = dns_send_req( ctx, name, T_SRV, &buffer, &resp_len );
420 if ( !NT_STATUS_IS_OK(status) ) {
421 DEBUG(3,("ads_dns_lookup_srv: Failed to send DNS query (%s)\n",
427 /* For some insane reason, the ns_initparse() et. al. routines are only
428 available in libresolv.a, and not the shared lib. Who knows why....
429 So we have to parse the DNS reply ourselves */
431 /* Pull the answer RR's count from the header.
432 * Use the NMB ordering macros */
434 query_count = RSVAL( p, 4 );
435 answer_count = RSVAL( p, 6 );
436 auth_count = RSVAL( p, 8 );
437 additional_count = RSVAL( p, 10 );
439 DEBUG(4,("ads_dns_lookup_srv: "
440 "%d records returned in the answer section.\n",
444 if ((dcs = talloc_zero_array(ctx, struct dns_rr_srv,
445 answer_count)) == NULL ) {
446 DEBUG(0,("ads_dns_lookup_srv: "
447 "talloc() failure for %d char*'s\n",
449 return NT_STATUS_NO_MEMORY;
455 /* now skip the header */
459 /* parse the query section */
461 for ( rrnum=0; rrnum<query_count; rrnum++ ) {
464 if (!ads_dns_parse_query(ctx, buffer,
465 buffer+resp_len, &p, &q)) {
466 DEBUG(1,("ads_dns_lookup_srv: "
467 "Failed to parse query record [%d]!\n", rrnum));
468 return NT_STATUS_UNSUCCESSFUL;
472 /* now we are at the answer section */
474 for ( rrnum=0; rrnum<answer_count; rrnum++ ) {
475 if (!ads_dns_parse_rr_srv(ctx, buffer, buffer+resp_len,
477 DEBUG(1,("ads_dns_lookup_srv: "
478 "Failed to parse answer recordi [%d]!\n", rrnum));
479 return NT_STATUS_UNSUCCESSFUL;
484 /* Parse the authority section */
485 /* just skip these for now */
487 for ( rrnum=0; rrnum<auth_count; rrnum++ ) {
490 if (!ads_dns_parse_rr( ctx, buffer,
491 buffer+resp_len, &p, &rr)) {
492 DEBUG(1,("ads_dns_lookup_srv: "
493 "Failed to parse authority record! [%d]\n", rrnum));
494 return NT_STATUS_UNSUCCESSFUL;
498 /* Parse the additional records section */
500 for ( rrnum=0; rrnum<additional_count; rrnum++ ) {
504 if (!ads_dns_parse_rr(ctx, buffer, buffer+resp_len,
506 DEBUG(1,("ads_dns_lookup_srv: Failed "
507 "to parse additional records section! [%d]\n", rrnum));
508 return NT_STATUS_UNSUCCESSFUL;
511 /* Only interested in A or AAAA records as a shortcut for having
512 * to come back later and lookup the name. For multi-homed
513 * hosts, the number of additional records and exceed the
514 * number of answer records. */
516 if (rr.type != T_A || rr.rdatalen != 4) {
517 #if defined(HAVE_IPV6)
518 /* RFC2874 defines A6 records. This
519 * requires recusive and horribly complex lookups.
520 * Bastards. Ignore this for now.... JRA.
521 * Luckily RFC3363 reprecates A6 records.
523 if (rr.type != T_AAAA || rr.rdatalen != 16)
528 for ( i=0; i<idx; i++ ) {
529 if ( strcmp( rr.hostname, dcs[i].hostname ) == 0 ) {
530 int num_ips = dcs[i].num_ips;
531 struct sockaddr_storage *tmp_ss_s;
533 /* allocate new memory */
535 if (dcs[i].num_ips == 0) {
536 if ((dcs[i].ss_s = talloc_array(dcs,
537 struct sockaddr_storage, 1 ))
539 return NT_STATUS_NO_MEMORY;
542 if ((tmp_ss_s = talloc_realloc(dcs,
544 struct sockaddr_storage,
547 return NT_STATUS_NO_MEMORY;
550 dcs[i].ss_s = tmp_ss_s;
554 /* copy the new IP address */
555 if (rr.type == T_A) {
557 memcpy(&ip, rr.rdata, 4);
558 in_addr_to_sockaddr_storage(
559 &dcs[i].ss_s[num_ips],
562 #if defined(HAVE_IPV6)
563 if (rr.type == T_AAAA) {
565 memcpy(&ip6, rr.rdata, rr.rdatalen);
566 in6_addr_to_sockaddr_storage(
567 &dcs[i].ss_s[num_ips],
575 TYPESAFE_QSORT(dcs, idx, dnssrvcmp );
583 /*********************************************************************
584 Simple wrapper for a DNS NS query
585 *********************************************************************/
587 NTSTATUS ads_dns_lookup_ns(TALLOC_CTX *ctx,
588 const char *dns_hosts_file,
589 const char *dnsdomain,
590 struct dns_rr_ns **nslist,
593 uint8_t *buffer = NULL;
595 struct dns_rr_ns *nsarray = NULL;
596 int query_count, answer_count, auth_count, additional_count;
602 if ( !ctx || !dnsdomain || !nslist ) {
603 return NT_STATUS_INVALID_PARAMETER;
606 if (dns_hosts_file) {
607 DEBUG(1, ("NO 'NS' lookup available when using resolv:host file"));
608 return NT_STATUS_OBJECT_NAME_NOT_FOUND;
611 /* Send the request. May have to loop several times in case
614 status = dns_send_req( ctx, dnsdomain, T_NS, &buffer, &resp_len );
615 if ( !NT_STATUS_IS_OK(status) ) {
616 DEBUG(3,("ads_dns_lookup_ns: Failed to send DNS query (%s)\n",
622 /* For some insane reason, the ns_initparse() et. al. routines are only
623 available in libresolv.a, and not the shared lib. Who knows why....
624 So we have to parse the DNS reply ourselves */
626 /* Pull the answer RR's count from the header.
627 * Use the NMB ordering macros */
629 query_count = RSVAL( p, 4 );
630 answer_count = RSVAL( p, 6 );
631 auth_count = RSVAL( p, 8 );
632 additional_count = RSVAL( p, 10 );
634 DEBUG(4,("ads_dns_lookup_ns: "
635 "%d records returned in the answer section.\n",
639 if ((nsarray = talloc_array(ctx, struct dns_rr_ns,
640 answer_count)) == NULL ) {
641 DEBUG(0,("ads_dns_lookup_ns: "
642 "talloc() failure for %d char*'s\n",
644 return NT_STATUS_NO_MEMORY;
650 /* now skip the header */
654 /* parse the query section */
656 for ( rrnum=0; rrnum<query_count; rrnum++ ) {
659 if (!ads_dns_parse_query(ctx, buffer, buffer+resp_len,
661 DEBUG(1,("ads_dns_lookup_ns: "
662 " Failed to parse query record!\n"));
663 return NT_STATUS_UNSUCCESSFUL;
667 /* now we are at the answer section */
669 for ( rrnum=0; rrnum<answer_count; rrnum++ ) {
670 if (!ads_dns_parse_rr_ns(ctx, buffer, buffer+resp_len,
671 &p, &nsarray[rrnum])) {
672 DEBUG(1,("ads_dns_lookup_ns: "
673 "Failed to parse answer record!\n"));
674 return NT_STATUS_UNSUCCESSFUL;
679 /* Parse the authority section */
680 /* just skip these for now */
682 for ( rrnum=0; rrnum<auth_count; rrnum++ ) {
685 if ( !ads_dns_parse_rr(ctx, buffer, buffer+resp_len,
687 DEBUG(1,("ads_dns_lookup_ns: "
688 "Failed to parse authority record!\n"));
689 return NT_STATUS_UNSUCCESSFUL;
693 /* Parse the additional records section */
695 for ( rrnum=0; rrnum<additional_count; rrnum++ ) {
699 if (!ads_dns_parse_rr(ctx, buffer, buffer+resp_len,
701 DEBUG(1,("ads_dns_lookup_ns: Failed "
702 "to parse additional records section!\n"));
703 return NT_STATUS_UNSUCCESSFUL;
706 /* only interested in A records as a shortcut for having to come
707 back later and lookup the name */
709 if (rr.type != T_A || rr.rdatalen != 4) {
710 #if defined(HAVE_IPV6)
711 if (rr.type != T_AAAA || rr.rdatalen != 16)
716 for ( i=0; i<idx; i++ ) {
717 if (strcmp(rr.hostname, nsarray[i].hostname) == 0) {
718 if (rr.type == T_A) {
720 memcpy(&ip, rr.rdata, 4);
721 in_addr_to_sockaddr_storage(
725 #if defined(HAVE_IPV6)
726 if (rr.type == T_AAAA) {
728 memcpy(&ip6, rr.rdata, rr.rdatalen);
729 in6_addr_to_sockaddr_storage(
744 /********************************************************************
745 Query with optional sitename.
746 ********************************************************************/
748 static NTSTATUS ads_dns_query_internal(TALLOC_CTX *ctx,
749 const char *dns_hosts_file,
750 const char *servicename,
751 const char *dc_pdc_gc_domains,
753 const char *sitename,
754 struct dns_rr_srv **dclist,
758 if (sitename && strlen(sitename)) {
759 name = talloc_asprintf(ctx, "%s._tcp.%s._sites.%s._msdcs.%s",
760 servicename, sitename,
761 dc_pdc_gc_domains, realm);
763 name = talloc_asprintf(ctx, "%s._tcp.%s._msdcs.%s",
764 servicename, dc_pdc_gc_domains, realm);
767 return NT_STATUS_NO_MEMORY;
769 return ads_dns_lookup_srv(ctx, dns_hosts_file, name, dclist, numdcs);
772 /********************************************************************
774 ********************************************************************/
776 NTSTATUS ads_dns_query_dcs(TALLOC_CTX *ctx,
777 const char *dns_hosts_file,
779 const char *sitename,
780 struct dns_rr_srv **dclist,
785 status = ads_dns_query_internal(ctx, dns_hosts_file, "_ldap", "dc",
786 realm, sitename, dclist, numdcs);
788 if (NT_STATUS_EQUAL(status, NT_STATUS_IO_TIMEOUT) ||
789 NT_STATUS_EQUAL(status, NT_STATUS_CONNECTION_REFUSED)) {
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, dns_hosts_file,
798 "_ldap", "dc", realm,
799 NULL, dclist, numdcs);
804 /********************************************************************
806 ********************************************************************/
808 NTSTATUS ads_dns_query_gcs(TALLOC_CTX *ctx,
809 const char *dns_hosts_file,
811 const char *sitename,
812 struct dns_rr_srv **dclist,
817 status = ads_dns_query_internal(ctx, dns_hosts_file, "_ldap", "gc",
818 realm, sitename, dclist, numdcs);
820 if (NT_STATUS_EQUAL(status, NT_STATUS_IO_TIMEOUT) ||
821 NT_STATUS_EQUAL(status, NT_STATUS_CONNECTION_REFUSED)) {
826 ((!NT_STATUS_IS_OK(status)) ||
827 (NT_STATUS_IS_OK(status) && (numdcs == 0)))) {
828 /* Sitename DNS query may have failed. Try without. */
829 status = ads_dns_query_internal(ctx, dns_hosts_file,
830 "_ldap", "gc", realm,
831 NULL, dclist, numdcs);
836 /********************************************************************
838 Even if our underlying kerberos libraries are UDP only, this
839 is pretty safe as it's unlikely that a KDC supports TCP and not UDP.
840 ********************************************************************/
842 NTSTATUS ads_dns_query_kdcs(TALLOC_CTX *ctx,
843 const char *dns_hosts_file,
844 const char *dns_forest_name,
845 const char *sitename,
846 struct dns_rr_srv **dclist,
851 status = ads_dns_query_internal(ctx, dns_hosts_file, "_kerberos", "dc",
852 dns_forest_name, sitename, dclist,
855 if (NT_STATUS_EQUAL(status, NT_STATUS_IO_TIMEOUT) ||
856 NT_STATUS_EQUAL(status, NT_STATUS_CONNECTION_REFUSED)) {
861 ((!NT_STATUS_IS_OK(status)) ||
862 (NT_STATUS_IS_OK(status) && (numdcs == 0)))) {
863 /* Sitename DNS query may have failed. Try without. */
864 status = ads_dns_query_internal(ctx, dns_hosts_file,
866 dns_forest_name, NULL,
872 /********************************************************************
873 Query for AD PDC. Sitename is obsolete here.
874 ********************************************************************/
876 NTSTATUS ads_dns_query_pdc(TALLOC_CTX *ctx,
877 const char *dns_hosts_file,
878 const char *dns_domain_name,
879 struct dns_rr_srv **dclist,
882 return ads_dns_query_internal(ctx, dns_hosts_file, "_ldap", "pdc",
883 dns_domain_name, NULL, dclist, numdcs);
886 /********************************************************************
887 Query for AD DC by guid. Sitename is obsolete here.
888 ********************************************************************/
890 NTSTATUS ads_dns_query_dcs_guid(TALLOC_CTX *ctx,
891 const char *dns_hosts_file,
892 const char *dns_forest_name,
893 const struct GUID *domain_guid,
894 struct dns_rr_srv **dclist,
897 /*_ldap._tcp.DomainGuid.domains._msdcs.DnsForestName */
902 guid_string = GUID_string(ctx, domain_guid);
904 return NT_STATUS_NO_MEMORY;
908 domains = talloc_asprintf(ctx, "%s.domains", guid_string);
910 return NT_STATUS_NO_MEMORY;
912 TALLOC_FREE(guid_string);
914 return ads_dns_query_internal(ctx, dns_hosts_file, "_ldap", domains,
915 dns_forest_name, NULL, dclist, numdcs);