source3/libsmb/conncache.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3
   4    Winbind daemon connection manager
   5
   6    Copyright (C) Tim Potter             2001
   7    Copyright (C) Andrew Bartlett        2002
   8    Copyright (C) Gerald (Jerry) Carter  2003
   9
  10    This program is free software; you can redistribute it and/or modify
  11    it under the terms of the GNU General Public License as published by
  12    the Free Software Foundation; either version 2 of the License, or
  13    (at your option) any later version.
  14
  15    This program is distributed in the hope that it will be useful,
  16    but WITHOUT ANY WARRANTY; without even the implied warranty of
  17    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18    GNU General Public License for more details.
  19
  20    You should have received a copy of the GNU General Public License
  21    along with this program; if not, write to the Free Software
  22    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  23 */
  24
  25
  26 #include "includes.h"
  27
  28 #define FAILED_CONNECTION_CACHE_TIMEOUT 30 /* Seconds between attempts */
  29
  30 #define CONNCACHE_ADDR          1
  31 #define CONNCACHE_NAME          2
  32
  33 /* cache entry contains either a server name **or** and IP address as
  34    the key.  This means that a server could have two entries (one for each key) */
  35
  36 struct failed_connection_cache {
  37         fstring         domain_name;
  38         fstring         controller;
  39         time_t          lookup_time;
  40         NTSTATUS        nt_status;
  41         struct failed_connection_cache *prev, *next;
  42 };
  43
  44 static struct failed_connection_cache *failed_connection_cache;
  45
  46 /**********************************************************************
  47  Check for a previously failed connection
  48 **********************************************************************/
  49
  50 NTSTATUS check_negative_conn_cache( const char *domain, const char *server )
  51 {
  52         struct failed_connection_cache *fcc;
  53         NTSTATUS result = NT_STATUS_UNSUCCESSFUL;
  54
  55         /* can't check if we don't have strings */
  56
  57         if ( !domain || !server )
  58                 return NT_STATUS_OK;
  59
  60         for (fcc = failed_connection_cache; fcc; fcc = fcc->next) {
  61
  62                 if ( !(strequal(domain, fcc->domain_name) && strequal(server, fcc->controller)) )
  63                         continue; /* no match; check the next entry */
  64
  65                 /* we have a match so see if it is still current */
  66
  67                 if ((time(NULL) - fcc->lookup_time) > FAILED_CONNECTION_CACHE_TIMEOUT)
  68                 {
  69                         /* Cache entry has expired, delete it */
  70
  71                         DEBUG(10, ("check_negative_conn_cache: cache entry expired for %s, %s\n",
  72                                 domain, server ));
  73
  74                         DLIST_REMOVE(failed_connection_cache, fcc);
  75                         SAFE_FREE(fcc);
  76
  77                         return NT_STATUS_OK;
  78                 }
  79
  80                 /* The timeout hasn't expired yet so return false */
  81
  82                 DEBUG(10, ("check_negative_conn_cache: returning negative entry for %s, %s\n",
  83                         domain, server ));
  84
  85                 result = fcc->nt_status;
  86                 return result;
  87         }
  88
  89         /* end of function means no cache entry */
  90         return NT_STATUS_OK;
  91 }
  92
  93 /**********************************************************************
  94  Add an entry to the failed conneciton cache (aither a name of dotted
  95  decimal IP
  96 **********************************************************************/
  97
  98 void add_failed_connection_entry(const char *domain, const char *server, NTSTATUS result)
  99 {
 100         struct failed_connection_cache *fcc;
 101
 102         SMB_ASSERT(!NT_STATUS_IS_OK(result));
 103
 104         /* Check we already aren't in the cache.  We always have to have
 105            a domain, but maybe not a specific DC name. */
 106
 107         for (fcc = failed_connection_cache; fcc; fcc = fcc->next) {
 108                 if ( strequal(fcc->domain_name, domain) && strequal(fcc->controller, server) )
 109                 {
 110                         DEBUG(10, ("add_failed_connection_entry: domain %s (%s) already tried and failed\n",
 111                                    domain, server ));
 112                         return;
 113                 }
 114         }
 115
 116         /* Create negative lookup cache entry for this domain and controller */
 117
 118         if ( !(fcc = (struct failed_connection_cache *)malloc(sizeof(struct failed_connection_cache))) )
 119         {
 120                 DEBUG(0, ("malloc failed in add_failed_connection_entry!\n"));
 121                 return;
 122         }
 123
 124         ZERO_STRUCTP(fcc);
 125
 126         fstrcpy( fcc->domain_name, domain );
 127         fstrcpy( fcc->controller, server );
 128         fcc->lookup_time = time(NULL);
 129         fcc->nt_status = result;
 130
 131         DEBUG(10,("add_failed_connection_entry: added domain %s (%s) to failed conn cache\n",
 132                 domain, server ));
 133
 134         DLIST_ADD(failed_connection_cache, fcc);
 135 }
 136
 137 /****************************************************************************
 138 ****************************************************************************/
 139
 140 void flush_negative_conn_cache( void )
 141 {
 142         struct failed_connection_cache *fcc;
 143
 144         fcc = failed_connection_cache;
 145
 146         while (fcc) {
 147                 struct failed_connection_cache *fcc_next;
 148
 149                 fcc_next = fcc->next;
 150                 DLIST_REMOVE(failed_connection_cache, fcc);
 151                 free(fcc);
 152
 153                 fcc = fcc_next;
 154         }
 155
 156 }
 157
 158