2 Unix SMB/CIFS implementation.
4 Copyright (C) Gerald (Jerry) Carter 2006.
6 This program is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2 of the License, or
9 (at your option) any later version.
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.
16 You should have received a copy of the GNU General Public License
17 along with this program; if not, write to the Free Software
18 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
23 /* AIX resolv.h uses 'class' in struct ns_rr */
31 /* resolver headers */
33 #include <sys/types.h>
34 #include <netinet/in.h>
35 #include <arpa/nameser.h>
39 #define MAX_DNS_PACKET_SIZE 0xffff
43 # define NS_HFIXEDSZ HFIXEDSZ
45 # define NS_HFIXEDSZ 12
49 /*********************************************************************
50 *********************************************************************/
52 static BOOL ads_dns_parse_query( TALLOC_CTX *ctx, uint8 *start, uint8 *end,
53 uint8 **ptr, struct dns_query *q )
61 if ( !start || !end || !q || !*ptr)
64 /* See RFC 1035 for details. If this fails, then return. */
66 namelen = dn_expand( start, end, p, hostname, sizeof(hostname) );
71 q->hostname = talloc_strdup( ctx, hostname );
73 /* check that we have space remaining */
75 if ( PTR_DIFF(p+4, end) > 0 )
78 q->type = RSVAL( p, 0 );
79 q->in_class = RSVAL( p, 2 );
87 /*********************************************************************
88 *********************************************************************/
90 static BOOL ads_dns_parse_rr( TALLOC_CTX *ctx, uint8 *start, uint8 *end,
91 uint8 **ptr, struct dns_rr *rr )
97 if ( !start || !end || !rr || !*ptr)
101 /* pull the name from the answer */
103 namelen = dn_expand( start, end, p, hostname, sizeof(hostname) );
108 rr->hostname = talloc_strdup( ctx, hostname );
110 /* check that we have space remaining */
112 if ( PTR_DIFF(p+10, end) > 0 )
115 /* pull some values and then skip onto the string */
117 rr->type = RSVAL(p, 0);
118 rr->in_class = RSVAL(p, 2);
119 rr->ttl = RIVAL(p, 4);
120 rr->rdatalen = RSVAL(p, 8);
124 /* sanity check the available space */
126 if ( PTR_DIFF(p+rr->rdatalen, end ) > 0 ) {
131 /* save a point to the rdata for this section */
141 /*********************************************************************
142 *********************************************************************/
144 static BOOL ads_dns_parse_rr_srv( TALLOC_CTX *ctx, uint8 *start, uint8 *end,
145 uint8 **ptr, struct dns_rr_srv *srv )
152 if ( !start || !end || !srv || !*ptr)
155 /* Parse the RR entry. Coming out of the this, ptr is at the beginning
156 of the next record */
158 if ( !ads_dns_parse_rr( ctx, start, end, ptr, &rr ) ) {
159 DEBUG(1,("ads_dns_parse_rr_srv: Failed to parse RR record\n"));
163 if ( rr.type != ns_t_srv ) {
164 DEBUG(1,("ads_dns_parse_rr_srv: Bad answer type (%d)\n", rr.type));
170 srv->priority = RSVAL(p, 0);
171 srv->weight = RSVAL(p, 2);
172 srv->port = RSVAL(p, 4);
176 namelen = dn_expand( start, end, p, dcname, sizeof(dcname) );
178 DEBUG(1,("ads_dns_parse_rr_srv: Failed to uncompress name!\n"));
181 srv->hostname = talloc_strdup( ctx, dcname );
187 /*********************************************************************
188 Sort SRV record list based on weight and priority. See RFC 2782.
189 *********************************************************************/
191 static int dnssrvcmp( struct dns_rr_srv *a, struct dns_rr_srv *b )
196 srand( (uint32)time(NULL) );
199 if ( a->priority == b->priority ) {
201 /* randomize entries with an equal weight and priority */
202 if ( a->weight == b->weight )
203 return rand() % 2 ? -1 : 1;
205 /* higher weights should be sorted lower */
206 if ( a->weight > b->weight )
212 if ( a->priority < b->priority )
218 /*********************************************************************
219 Simple wrapper for a DNS SRV query
220 *********************************************************************/
222 NTSTATUS ads_dns_lookup_srv( TALLOC_CTX *ctx, const char *name, struct dns_rr_srv **dclist, int *numdcs )
224 uint8 *buffer = NULL;
226 int resp_len = NS_PACKETSZ;
227 struct dns_rr_srv *dcs = NULL;
228 int query_count, answer_count, auth_count, additional_count;
233 if ( !ctx || !name || !dclist ) {
234 return NT_STATUS_INVALID_PARAMETER;
237 /* Send the request. May have to loop several times in case
242 TALLOC_FREE( buffer );
244 buf_len = resp_len * sizeof(uint8);
246 if ( (buffer = TALLOC_ARRAY(ctx, uint8, buf_len)) == NULL ) {
247 DEBUG(0,("ads_dns_lookup_srv: talloc() failed!\n"));
248 return NT_STATUS_NO_MEMORY;
251 if ( (resp_len = res_query(name, ns_c_in, ns_t_srv, buffer, buf_len)) < 0 ) {
252 DEBUG(1,("ads_dns_lookup_srv: Failed to resolve %s (%s)\n", name, strerror(errno)));
253 TALLOC_FREE( buffer );
254 return NT_STATUS_UNSUCCESSFUL;
256 } while ( buf_len < resp_len && resp_len < MAX_DNS_PACKET_SIZE );
260 /* For some insane reason, the ns_initparse() et. al. routines are only
261 available in libresolv.a, and not the shared lib. Who knows why....
262 So we have to parse the DNS reply ourselves */
264 /* Pull the answer RR's count from the header. Use the NMB ordering macros */
266 query_count = RSVAL( p, 4 );
267 answer_count = RSVAL( p, 6 );
268 auth_count = RSVAL( p, 8 );
269 additional_count = RSVAL( p, 10 );
271 DEBUG(4,("ads_dns_lookup_srv: %d records returned in the answer section.\n",
274 if ( (dcs = TALLOC_ARRAY(ctx, struct dns_rr_srv, answer_count)) == NULL ) {
275 DEBUG(0,("ads_dns_lookup_srv: talloc() failure for %d char*'s\n",
277 return NT_STATUS_NO_MEMORY;
280 /* now skip the header */
284 /* parse the query section */
286 for ( rrnum=0; rrnum<query_count; rrnum++ ) {
289 if ( !ads_dns_parse_query( ctx, buffer, buffer+resp_len, &p, &q ) ) {
290 DEBUG(1,("ads_dns_lookup_srv: Failed to parse query record!\n"));
291 return NT_STATUS_UNSUCCESSFUL;
295 /* now we are at the answer section */
297 for ( rrnum=0; rrnum<answer_count; rrnum++ ) {
298 if ( !ads_dns_parse_rr_srv( ctx, buffer, buffer+resp_len, &p, &dcs[rrnum] ) ) {
299 DEBUG(1,("ads_dns_lookup_srv: Failed to parse answer record!\n"));
300 return NT_STATUS_UNSUCCESSFUL;
305 /* Parse the authority section */
306 /* just skip these for now */
308 for ( rrnum=0; rrnum<auth_count; rrnum++ ) {
311 if ( !ads_dns_parse_rr( ctx, buffer, buffer+resp_len, &p, &rr ) ) {
312 DEBUG(1,("ads_dns_lookup_srv: Failed to parse authority record!\n"));
313 return NT_STATUS_UNSUCCESSFUL;
317 /* Parse the additional records section */
319 for ( rrnum=0; rrnum<additional_count; rrnum++ ) {
323 if ( !ads_dns_parse_rr( ctx, buffer, buffer+resp_len, &p, &rr ) ) {
324 DEBUG(1,("ads_dns_lookup_srv: Failed to parse additional records section!\n"));
325 return NT_STATUS_UNSUCCESSFUL;
328 /* only interested in A records as a shortcut for having to come
329 back later and lookup the name */
331 if ( (rr.type != ns_t_a) || (rr.rdatalen != 4) )
334 for ( i=0; i<idx; i++ ) {
335 if ( strcmp( rr.hostname, dcs[i].hostname ) == 0 ) {
336 uint8 *buf = (uint8*)&dcs[i].ip.s_addr;
337 memcpy( buf, rr.rdata, 4 );
342 qsort( dcs, idx, sizeof(struct dns_rr_srv), QSORT_CAST dnssrvcmp );
350 /********************************************************************
351 ********************************************************************/
353 NTSTATUS ads_dns_query_dcs( TALLOC_CTX *ctx, const char *domain, struct dns_rr_srv **dclist, int *numdcs )
357 snprintf( name, sizeof(name), "_ldap._tcp.dc._msdcs.%s", domain );
359 return ads_dns_lookup_srv( ctx, name, dclist, numdcs );