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 *start, uint8 *end,
79 uint8 **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 *start, uint8 *end,
117 uint8 **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 *start, uint8 *end,
171 uint8 **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 *start, uint8 *end,
224 uint8 **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 **buf, int *resp_length )
296 uint8 *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);
331 if ((buffer = TALLOC_ARRAY(ctx, uint8, 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,
393 struct dns_rr_srv **dclist,
396 uint8 *buffer = NULL;
398 struct dns_rr_srv *dcs = NULL;
399 int query_count, answer_count, auth_count, additional_count;
404 const char *dns_hosts_file;
406 if ( !ctx || !name || !dclist ) {
407 return NT_STATUS_INVALID_PARAMETER;
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,
417 /* Send the request. May have to loop several times in case
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",
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 */
432 /* Pull the answer RR's count from the header.
433 * Use the NMB ordering macros */
435 query_count = RSVAL( p, 4 );
436 answer_count = RSVAL( p, 6 );
437 auth_count = RSVAL( p, 8 );
438 additional_count = RSVAL( p, 10 );
440 DEBUG(4,("ads_dns_lookup_srv: "
441 "%d records returned in the answer section.\n",
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",
450 return NT_STATUS_NO_MEMORY;
456 /* now skip the header */
460 /* parse the query section */
462 for ( rrnum=0; rrnum<query_count; rrnum++ ) {
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;
473 /* now we are at the answer section */
475 for ( rrnum=0; rrnum<answer_count; rrnum++ ) {
476 if (!ads_dns_parse_rr_srv(ctx, buffer, buffer+resp_len,
478 DEBUG(1,("ads_dns_lookup_srv: "
479 "Failed to parse answer recordi [%d]!\n", rrnum));
480 return NT_STATUS_UNSUCCESSFUL;
485 /* Parse the authority section */
486 /* just skip these for now */
488 for ( rrnum=0; rrnum<auth_count; rrnum++ ) {
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;
499 /* Parse the additional records section */
501 for ( rrnum=0; rrnum<additional_count; rrnum++ ) {
505 if (!ads_dns_parse_rr(ctx, buffer, buffer+resp_len,
507 DEBUG(1,("ads_dns_lookup_srv: Failed "
508 "to parse additional records section! [%d]\n", rrnum));
509 return NT_STATUS_UNSUCCESSFUL;
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. */
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.
524 if (rr.type != T_AAAA || rr.rdatalen != 16)
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;
534 /* allocate new memory */
536 if (dcs[i].num_ips == 0) {
537 if ((dcs[i].ss_s = TALLOC_ARRAY(dcs,
538 struct sockaddr_storage, 1 ))
540 return NT_STATUS_NO_MEMORY;
543 if ((tmp_ss_s = TALLOC_REALLOC_ARRAY(dcs,
545 struct sockaddr_storage,
548 return NT_STATUS_NO_MEMORY;
551 dcs[i].ss_s = tmp_ss_s;
555 /* copy the new IP address */
556 if (rr.type == T_A) {
558 memcpy(&ip, rr.rdata, 4);
559 in_addr_to_sockaddr_storage(
560 &dcs[i].ss_s[num_ips],
563 #if defined(HAVE_IPV6)
564 if (rr.type == T_AAAA) {
566 memcpy(&ip6, rr.rdata, rr.rdatalen);
567 in6_addr_to_sockaddr_storage(
568 &dcs[i].ss_s[num_ips],
576 TYPESAFE_QSORT(dcs, idx, dnssrvcmp );
584 /*********************************************************************
585 Simple wrapper for a DNS NS query
586 *********************************************************************/
588 NTSTATUS ads_dns_lookup_ns(TALLOC_CTX *ctx,
589 const char *dnsdomain,
590 struct dns_rr_ns **nslist,
593 uint8 *buffer = NULL;
595 struct dns_rr_ns *nsarray = NULL;
596 int query_count, answer_count, auth_count, additional_count;
601 const char *dns_hosts_file;
603 if ( !ctx || !dnsdomain || !nslist ) {
604 return NT_STATUS_INVALID_PARAMETER;
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;
613 /* Send the request. May have to loop several times in case
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",
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 */
628 /* Pull the answer RR's count from the header.
629 * Use the NMB ordering macros */
631 query_count = RSVAL( p, 4 );
632 answer_count = RSVAL( p, 6 );
633 auth_count = RSVAL( p, 8 );
634 additional_count = RSVAL( p, 10 );
636 DEBUG(4,("ads_dns_lookup_ns: "
637 "%d records returned in the answer section.\n",
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",
646 return NT_STATUS_NO_MEMORY;
652 /* now skip the header */
656 /* parse the query section */
658 for ( rrnum=0; rrnum<query_count; rrnum++ ) {
661 if (!ads_dns_parse_query(ctx, buffer, buffer+resp_len,
663 DEBUG(1,("ads_dns_lookup_ns: "
664 " Failed to parse query record!\n"));
665 return NT_STATUS_UNSUCCESSFUL;
669 /* now we are at the answer section */
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;
681 /* Parse the authority section */
682 /* just skip these for now */
684 for ( rrnum=0; rrnum<auth_count; rrnum++ ) {
687 if ( !ads_dns_parse_rr(ctx, buffer, buffer+resp_len,
689 DEBUG(1,("ads_dns_lookup_ns: "
690 "Failed to parse authority record!\n"));
691 return NT_STATUS_UNSUCCESSFUL;
695 /* Parse the additional records section */
697 for ( rrnum=0; rrnum<additional_count; rrnum++ ) {
701 if (!ads_dns_parse_rr(ctx, buffer, buffer+resp_len,
703 DEBUG(1,("ads_dns_lookup_ns: Failed "
704 "to parse additional records section!\n"));
705 return NT_STATUS_UNSUCCESSFUL;
708 /* only interested in A records as a shortcut for having to come
709 back later and lookup the name */
711 if (rr.type != T_A || rr.rdatalen != 4) {
712 #if defined(HAVE_IPV6)
713 if (rr.type != T_AAAA || rr.rdatalen != 16)
718 for ( i=0; i<idx; i++ ) {
719 if (strcmp(rr.hostname, nsarray[i].hostname) == 0) {
720 if (rr.type == T_A) {
722 memcpy(&ip, rr.rdata, 4);
723 in_addr_to_sockaddr_storage(
727 #if defined(HAVE_IPV6)
728 if (rr.type == T_AAAA) {
730 memcpy(&ip6, rr.rdata, rr.rdatalen);
731 in6_addr_to_sockaddr_storage(
746 /********************************************************************
747 Query with optional sitename.
748 ********************************************************************/
750 static NTSTATUS ads_dns_query_internal(TALLOC_CTX *ctx,
751 const char *servicename,
752 const char *dc_pdc_gc_domains,
754 const char *sitename,
755 struct dns_rr_srv **dclist,
760 name = talloc_asprintf(ctx, "%s._tcp.%s._sites.%s._msdcs.%s",
761 servicename, sitename,
762 dc_pdc_gc_domains, realm);
764 name = talloc_asprintf(ctx, "%s._tcp.%s._msdcs.%s",
765 servicename, dc_pdc_gc_domains, realm);
768 return NT_STATUS_NO_MEMORY;
770 return ads_dns_lookup_srv( ctx, name, dclist, numdcs );
773 /********************************************************************
775 ********************************************************************/
777 NTSTATUS ads_dns_query_dcs(TALLOC_CTX *ctx,
779 const char *sitename,
780 struct dns_rr_srv **dclist,
785 status = ads_dns_query_internal(ctx, "_ldap", "dc", realm, sitename,
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, "_ldap", "dc", realm,
798 NULL, dclist, numdcs);
803 /********************************************************************
805 ********************************************************************/
807 NTSTATUS ads_dns_query_gcs(TALLOC_CTX *ctx,
809 const char *sitename,
810 struct dns_rr_srv **dclist,
815 status = ads_dns_query_internal(ctx, "_ldap", "gc", realm, sitename,
818 if (NT_STATUS_EQUAL(status, NT_STATUS_IO_TIMEOUT) ||
819 NT_STATUS_EQUAL(status, NT_STATUS_CONNECTION_REFUSED)) {
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);
833 /********************************************************************
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 ********************************************************************/
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,
847 status = ads_dns_query_internal(ctx, "_kerberos", "dc",
848 dns_forest_name, sitename, dclist,
851 if (NT_STATUS_EQUAL(status, NT_STATUS_IO_TIMEOUT) ||
852 NT_STATUS_EQUAL(status, NT_STATUS_CONNECTION_REFUSED)) {
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,
867 /********************************************************************
868 Query for AD PDC. Sitename is obsolete here.
869 ********************************************************************/
871 NTSTATUS ads_dns_query_pdc(TALLOC_CTX *ctx,
872 const char *dns_domain_name,
873 struct dns_rr_srv **dclist,
876 return ads_dns_query_internal(ctx, "_ldap", "pdc", dns_domain_name,
877 NULL, dclist, numdcs);
880 /********************************************************************
881 Query for AD DC by guid. Sitename is obsolete here.
882 ********************************************************************/
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,
890 /*_ldap._tcp.DomainGuid.domains._msdcs.DnsForestName */
895 guid_string = GUID_string(ctx, domain_guid);
897 return NT_STATUS_NO_MEMORY;
901 domains = talloc_asprintf(ctx, "%s.domains", guid_string);
903 return NT_STATUS_NO_MEMORY;
905 TALLOC_FREE(guid_string);
907 return ads_dns_query_internal(ctx, "_ldap", domains, dns_forest_name,
908 NULL, dclist, numdcs);