r23784: use the GPLv3 boilerplate as recommended by the FSF and the license text

[vlendec/samba-autobuild/.git] / source3 / libads / dns.c

diff --git a/source3/libads/dns.c b/source3/libads/dns.c
index f16cea25554ed0e540e2af1786c5e1c560d74b8c..96cd54af06e231cda30ec41e6678ec9d8c033ae4 100644 (file)
--- a/source3/libads/dns.c
+++ b/source3/libads/dns.c
@@ -5,7 +5,7 @@
 
    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
+   the Free Software Foundation; either version 3 of the License, or
    (at your option) any later version.
    
    This program is distributed in the hope that it will be useful,
@@ -14,8 +14,7 @@
    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.
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
 #include "includes.h"
@@ -270,45 +269,76 @@ static int dnssrvcmp( struct dns_rr_srv *a, struct dns_rr_srv *b )
  Simple wrapper for a DNS query
 *********************************************************************/
 
+#define DNS_FAILED_WAITTIME          30
+
 static NTSTATUS dns_send_req( TALLOC_CTX *ctx, const char *name, int q_type, 
                               uint8 **buf, int *resp_length )
 {
        uint8 *buffer = NULL;
        size_t buf_len;
        int resp_len = NS_PACKETSZ;     
-       
+       static time_t last_dns_check = 0;
+       static NTSTATUS last_dns_status = NT_STATUS_OK; 
+       time_t now = time(NULL);
+
+       /* Try to prevent bursts of DNS lookups if the server is down */
+
+       /* Protect against large clock changes */
+
+       if ( last_dns_check > now )
+               last_dns_check = 0;
+
+       /* IF we had a DNS timeout or a bad server and we are still 
+          in the 30 second cache window, just return the previous 
+          status and save the network timeout. */
+
+       if ( (NT_STATUS_EQUAL(last_dns_status,NT_STATUS_IO_TIMEOUT) ||
+             NT_STATUS_EQUAL(last_dns_status,NT_STATUS_CONNECTION_REFUSED)) &&
+            (last_dns_check+DNS_FAILED_WAITTIME) > now ) 
+       {
+               DEBUG(10,("last_dns_check: Returning cached status (%s)\n",
+                         nt_errstr(last_dns_status) ));
+               return last_dns_status;
+       }
+
+       /* Send the Query */
        do {
                if ( buffer )
                        TALLOC_FREE( buffer );
                
                buf_len = resp_len * sizeof(uint8);
 
-               if (buf_len) {
+               if (buf_len) {                  
                        if ( (buffer = TALLOC_ARRAY(ctx, uint8, buf_len)) == NULL ) {
                                DEBUG(0,("ads_dns_lookup_srv: talloc() failed!\n"));
-                               return NT_STATUS_NO_MEMORY;
+                               last_dns_status = NT_STATUS_NO_MEMORY;
+                               last_dns_check = time(NULL);
+                               return last_dns_status; 
                        }
-               } else {
-                       buffer = NULL;
                }
 
                if ( (resp_len = res_query(name, C_IN, q_type, buffer, buf_len)) < 0 ) {
                        DEBUG(3,("ads_dns_lookup_srv: Failed to resolve %s (%s)\n", name, strerror(errno)));
                        TALLOC_FREE( buffer );
+                       last_dns_status = NT_STATUS_UNSUCCESSFUL;
+                       
                        if (errno == ETIMEDOUT) {
-                               return NT_STATUS_IO_TIMEOUT;
+                               last_dns_status = NT_STATUS_IO_TIMEOUT;                         
                        }
                        if (errno == ECONNREFUSED) {
-                               return NT_STATUS_CONNECTION_REFUSED;
+                               last_dns_status = NT_STATUS_CONNECTION_REFUSED;                         
                        }
-                       return NT_STATUS_UNSUCCESSFUL;
+                       last_dns_check = time(NULL);
+                       return last_dns_status;
                }
        } while ( buf_len < resp_len && resp_len < MAX_DNS_PACKET_SIZE );
        
        *buf = buffer;
        *resp_length = resp_len;
 
-       return NT_STATUS_OK;
+       last_dns_check = time(NULL);
+       last_dns_status = NT_STATUS_OK; 
+       return last_dns_status;
 }
 
 /*********************************************************************
@@ -606,8 +636,6 @@ static char *sitename_key(const char *realm)
 /****************************************************************************
  Store the AD client sitename.
  We store indefinately as every new CLDAP query will re-write this.
- If the sitename is "Default-First-Site-Name" we don't store it
- as this isn't a valid DNS name.
 ****************************************************************************/
 
 BOOL sitename_store(const char *realm, const char *sitename)
@@ -621,7 +649,7 @@ BOOL sitename_store(const char *realm, const char *sitename)
        }
 
        if (!realm || (strlen(realm) == 0)) {
-               DEBUG(0,("no realm\n"));
+               DEBUG(0,("sitename_store: no realm\n"));
                return False;
        }
        
@@ -692,7 +720,7 @@ BOOL stored_sitename_changed(const char *realm, const char *sitename)
        char *new_sitename;
 
        if (!realm || (strlen(realm) == 0)) {
-               DEBUG(0,("no realm\n"));
+               DEBUG(0,("stored_sitename_changed: no realm\n"));
                return False;
        }