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-rw-r--r--source3/libads/dns.c353
1 files changed, 353 insertions, 0 deletions
diff --git a/source3/libads/dns.c b/source3/libads/dns.c
new file mode 100644
index 0000000000..0119ae9130
--- /dev/null
+++ b/source3/libads/dns.c
@@ -0,0 +1,353 @@
+/*
+ Unix SMB/CIFS implementation.
+ DNS utility library
+ Copyright (C) Gerald (Jerry) Carter 2006.
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 2 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program; if not, write to the Free Software
+ Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+*/
+
+#include "includes.h"
+
+/* AIX resolv.h uses 'class' in struct ns_rr */
+
+#if defined(AIX)
+# if defined(class)
+# undef class
+# endif
+#endif /* AIX */
+
+/* resolver headers */
+
+#include <sys/types.h>
+#include <netinet/in.h>
+#include <arpa/nameser.h>
+#include <resolv.h>
+#include <netdb.h>
+
+#define MAX_DNS_PACKET_SIZE 0xffff
+
+/*********************************************************************
+*********************************************************************/
+
+static BOOL ads_dns_parse_query( TALLOC_CTX *ctx, uint8 *start, uint8 *end,
+ uint8 **ptr, struct dns_query *q )
+{
+ uint8 *p = *ptr;
+ pstring hostname;
+ int namelen;
+
+ ZERO_STRUCTP( q );
+
+ if ( !start || !end || !q || !*ptr)
+ return False;
+
+ /* See RFC 1035 for details. If this fails, then return. */
+
+ namelen = dn_expand( start, end, p, hostname, sizeof(hostname) );
+ if ( namelen < 0 ) {
+ return False;
+ }
+ p += namelen;
+ q->hostname = talloc_strdup( ctx, hostname );
+
+ /* check that we have space remaining */
+
+ if ( PTR_DIFF(p+4, end) > 0 )
+ return False;
+
+ q->type = RSVAL( p, 0 );
+ q->in_class = RSVAL( p, 2 );
+ p += 4;
+
+ *ptr = p;
+
+ return True;
+}
+
+/*********************************************************************
+*********************************************************************/
+
+static BOOL ads_dns_parse_rr( TALLOC_CTX *ctx, uint8 *start, uint8 *end,
+ uint8 **ptr, struct dns_rr *rr )
+{
+ uint8 *p = *ptr;
+ pstring hostname;
+ int namelen;
+
+ if ( !start || !end || !rr || !*ptr)
+ return -1;
+
+ ZERO_STRUCTP( rr );
+ /* pull the name from the answer */
+
+ namelen = dn_expand( start, end, p, hostname, sizeof(hostname) );
+ if ( namelen < 0 ) {
+ return -1;
+ }
+ p += namelen;
+ rr->hostname = talloc_strdup( ctx, hostname );
+
+ /* check that we have space remaining */
+
+ if ( PTR_DIFF(p+10, end) > 0 )
+ return False;
+
+ /* pull some values and then skip onto the string */
+
+ rr->type = RSVAL(p, 0);
+ rr->in_class = RSVAL(p, 2);
+ rr->ttl = RIVAL(p, 4);
+ rr->rdatalen = RSVAL(p, 8);
+
+ p += 10;
+
+ /* sanity check the available space */
+
+ if ( PTR_DIFF(p+rr->rdatalen, end ) > 0 ) {
+ return False;
+
+ }
+
+ /* save a point to the rdata for this section */
+
+ rr->rdata = p;
+ p += rr->rdatalen;
+
+ *ptr = p;
+
+ return True;
+}
+
+/*********************************************************************
+*********************************************************************/
+
+static BOOL ads_dns_parse_rr_srv( TALLOC_CTX *ctx, uint8 *start, uint8 *end,
+ uint8 **ptr, struct dns_rr_srv *srv )
+{
+ struct dns_rr rr;
+ uint8 *p;
+ pstring dcname;
+ int namelen;
+
+ if ( !start || !end || !srv || !*ptr)
+ return -1;
+
+ /* Parse the RR entry. Coming out of the this, ptr is at the beginning
+ of the next record */
+
+ if ( !ads_dns_parse_rr( ctx, start, end, ptr, &rr ) ) {
+ DEBUG(1,("ads_dns_parse_rr_srv: Failed to parse RR record\n"));
+ return False;
+ }
+
+ if ( rr.type != ns_t_srv ) {
+ DEBUG(1,("ads_dns_parse_rr_srv: Bad answer type (%d)\n", rr.type));
+ return False;
+ }
+
+ p = rr.rdata;
+
+ srv->priority = RSVAL(p, 0);
+ srv->weight = RSVAL(p, 2);
+ srv->port = RSVAL(p, 4);
+
+ p += 6;
+
+ namelen = dn_expand( start, end, p, dcname, sizeof(dcname) );
+ if ( namelen < 0 ) {
+ DEBUG(1,("ads_dns_parse_rr_srv: Failed to uncompress name!\n"));
+ return False;
+ }
+ srv->hostname = talloc_strdup( ctx, dcname );
+
+ return True;
+}
+
+
+/*********************************************************************
+ Sort SRV record list based on weight and priority. See RFC 2782.
+*********************************************************************/
+
+static int dnssrvcmp( struct dns_rr_srv *a, struct dns_rr_srv *b )
+{
+ BOOL init = False;
+
+ if ( !init ) {
+ srand( (uint32)time(NULL) );
+ }
+
+ if ( a->priority == b->priority ) {
+
+ /* randomize entries with an equal weight and priority */
+ if ( a->weight == b->weight )
+ return rand() % 2 ? -1 : 1;
+
+ /* higher weights should be sorted lower */
+ if ( a->weight > b->weight )
+ return -1;
+ else
+ return 1;
+ }
+
+ if ( a->priority < b->priority )
+ return -1;
+
+ return 1;
+}
+
+/*********************************************************************
+ Simple wrapper for a DNS SRV query
+*********************************************************************/
+
+NTSTATUS ads_dns_lookup_srv( TALLOC_CTX *ctx, const char *name, struct dns_rr_srv **dclist, int *numdcs )
+{
+ uint8 *buffer = NULL;
+ size_t buf_len;
+ int resp_len = NS_PACKETSZ;
+ struct dns_rr_srv *dcs = NULL;
+ int query_count, answer_count, auth_count, additional_count;
+ uint8 *p = buffer;
+ int rrnum;
+ int idx = 0;
+
+ if ( !ctx || !name || !dclist ) {
+ return NT_STATUS_INVALID_PARAMETER;
+ }
+
+ /* Send the request. May have to loop several times in case
+ of large replies */
+
+ do {
+ if ( buffer )
+ TALLOC_FREE( buffer );
+
+ buf_len = resp_len * sizeof(uint8);
+
+ if ( (buffer = TALLOC_ARRAY(ctx, uint8, buf_len)) == NULL ) {
+ DEBUG(0,("ads_dns_lookup_srv: talloc() failed!\n"));
+ return NT_STATUS_NO_MEMORY;
+ }
+
+ if ( (resp_len = res_query(name, ns_c_in, ns_t_srv, buffer, buf_len)) < 0 ) {
+ DEBUG(1,("ads_dns_lookup_srv: Failed to resolve %s (%s)\n", name, strerror(errno)));
+ TALLOC_FREE( buffer );
+ return NT_STATUS_UNSUCCESSFUL;
+ }
+ } while ( buf_len < resp_len && resp_len < MAX_DNS_PACKET_SIZE );
+
+ p = buffer;
+
+ /* For some insane reason, the ns_initparse() et. al. routines are only
+ available in libresolv.a, and not the shared lib. Who knows why....
+ So we have to parse the DNS reply ourselves */
+
+ /* Pull the answer RR's count from the header. Use the NMB ordering macros */
+
+ query_count = RSVAL( p, 4 );
+ answer_count = RSVAL( p, 6 );
+ auth_count = RSVAL( p, 8 );
+ additional_count = RSVAL( p, 10 );
+
+ DEBUG(4,("ads_dns_lookup_srv: %d records returned in the answer section.\n",
+ answer_count));
+
+ if ( (dcs = TALLOC_ARRAY(ctx, struct dns_rr_srv, answer_count)) == NULL ) {
+ DEBUG(0,("ads_dns_lookup_srv: talloc() failure for %d char*'s\n",
+ answer_count));
+ return NT_STATUS_NO_MEMORY;
+ }
+
+ /* now skip the header */
+
+ p += NS_HFIXEDSZ;
+
+ /* parse the query section */
+
+ for ( rrnum=0; rrnum<query_count; rrnum++ ) {
+ struct dns_query q;
+
+ if ( !ads_dns_parse_query( ctx, buffer, buffer+resp_len, &p, &q ) ) {
+ DEBUG(1,("ads_dns_lookup_srv: Failed to parse query record!\n"));
+ return NT_STATUS_UNSUCCESSFUL;
+ }
+ }
+
+ /* now we are at the answer section */
+
+ for ( rrnum=0; rrnum<answer_count; rrnum++ ) {
+ if ( !ads_dns_parse_rr_srv( ctx, buffer, buffer+resp_len, &p, &dcs[rrnum] ) ) {
+ DEBUG(1,("ads_dns_lookup_srv: Failed to parse answer record!\n"));
+ return NT_STATUS_UNSUCCESSFUL;
+ }
+ }
+ idx = rrnum;
+
+ /* Parse the authority section */
+ /* just skip these for now */
+
+ for ( rrnum=0; rrnum<auth_count; rrnum++ ) {
+ struct dns_rr rr;
+
+ if ( !ads_dns_parse_rr( ctx, buffer, buffer+resp_len, &p, &rr ) ) {
+ DEBUG(1,("ads_dns_lookup_srv: Failed to parse authority record!\n"));
+ return NT_STATUS_UNSUCCESSFUL;
+ }
+ }
+
+ /* Parse the additional records section */
+
+ for ( rrnum=0; rrnum<additional_count; rrnum++ ) {
+ struct dns_rr rr;
+ int i;
+
+ if ( !ads_dns_parse_rr( ctx, buffer, buffer+resp_len, &p, &rr ) ) {
+ DEBUG(1,("ads_dns_lookup_srv: Failed to parse additional records section!\n"));
+ return NT_STATUS_UNSUCCESSFUL;
+ }
+
+ /* only interested in A records as a shortcut for having to come
+ back later and lookup the name */
+
+ if ( (rr.type != ns_t_a) || (rr.rdatalen != 4) )
+ continue;
+
+ for ( i=0; i<idx; i++ ) {
+ if ( strcmp( rr.hostname, dcs[i].hostname ) == 0 ) {
+ uint8 *buf = (uint8*)&dcs[i].ip.s_addr;
+ memcpy( buf, rr.rdata, 4 );
+ }
+ }
+ }
+
+ qsort( dcs, idx, sizeof(struct dns_rr_srv), QSORT_CAST dnssrvcmp );
+
+ *dclist = dcs;
+ *numdcs = idx;
+
+ return NT_STATUS_OK;
+}
+
+/********************************************************************
+********************************************************************/
+
+NTSTATUS ads_dns_query_dcs( TALLOC_CTX *ctx, const char *domain, struct dns_rr_srv **dclist, int *numdcs )
+{
+ pstring name;
+
+ snprintf( name, sizeof(name), "_ldap._tcp.dc._msdcs.%s", domain );
+
+ return ads_dns_lookup_srv( ctx, name, dclist, numdcs );
+}
+
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