source/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 CONNCACHE_ADDR          1
  29 #define CONNCACHE_NAME          2
  30
  31 /* cache entry contains either a server name **or** and IP address as
  32    the key.  This means that a server could have two entries (one for each key) */
  33
  34 struct failed_connection_cache {
  35         fstring         domain_name;
  36         fstring         controller;
  37         time_t          lookup_time;
  38         NTSTATUS        nt_status;
  39         struct failed_connection_cache *prev, *next;
  40 };
  41
  42 static struct failed_connection_cache *failed_connection_cache;
  43
  44 /**********************************************************************
  45  Check for a previously failed connection.
  46  failed_cache_timeout is an a absolute number of seconds after which
  47  we should time this out. If failed_cache_timeout == 0 then time out
  48  immediately. If failed_cache_timeout == -1 then never time out.
  49 **********************************************************************/
  50
  51 NTSTATUS check_negative_conn_cache_timeout( const char *domain, const char *server, unsigned int failed_cache_timeout )
  52 {
  53         struct failed_connection_cache *fcc;
  54         NTSTATUS result = NT_STATUS_UNSUCCESSFUL;
  55
  56         /* can't check if we don't have strings */
  57
  58         if ( !domain || !server )
  59                 return NT_STATUS_OK;
  60
  61         for (fcc = failed_connection_cache; fcc; fcc = fcc->next) {
  62
  63                 if (!(strequal(domain, fcc->domain_name) && strequal(server, fcc->controller))) {
  64                         continue; /* no match; check the next entry */
  65                 }
  66
  67                 /* we have a match so see if it is still current */
  68                 if (failed_cache_timeout != (unsigned int)-1) {
  69                         if (failed_cache_timeout == 0 ||
  70                                         (time(NULL) - fcc->lookup_time) > (time_t)failed_cache_timeout) {
  71                                 /* Cache entry has expired, delete it */
  72
  73                                 DEBUG(10, ("check_negative_conn_cache: cache entry expired for %s, %s\n",
  74                                         domain, server ));
  75
  76                                 DLIST_REMOVE(failed_connection_cache, fcc);
  77                                 SAFE_FREE(fcc);
  78
  79                                 return NT_STATUS_OK;
  80                         }
  81                 }
  82
  83                 /* The timeout hasn't expired yet so return false */
  84
  85                 DEBUG(10, ("check_negative_conn_cache: returning negative entry for %s, %s\n",
  86                         domain, server ));
  87
  88                 result = fcc->nt_status;
  89                 return result;
  90         }
  91
  92         /* end of function means no cache entry */
  93         return NT_STATUS_OK;
  94 }
  95
  96 NTSTATUS check_negative_conn_cache( const char *domain, const char *server)
  97 {
  98         return check_negative_conn_cache_timeout(domain, server, FAILED_CONNECTION_CACHE_TIMEOUT);
  99 }
 100
 101 /**********************************************************************
 102  Add an entry to the failed conneciton cache (aither a name of dotted
 103  decimal IP
 104 **********************************************************************/
 105
 106 void add_failed_connection_entry(const char *domain, const char *server, NTSTATUS result)
 107 {
 108         struct failed_connection_cache *fcc;
 109
 110         SMB_ASSERT(!NT_STATUS_IS_OK(result));
 111
 112         /* Check we already aren't in the cache.  We always have to have
 113            a domain, but maybe not a specific DC name. */
 114
 115         for (fcc = failed_connection_cache; fcc; fcc = fcc->next) {
 116                 if ( strequal(fcc->domain_name, domain) && strequal(fcc->controller, server) ) {
 117                         DEBUG(10, ("add_failed_connection_entry: domain %s (%s) already tried and failed\n",
 118                                    domain, server ));
 119                         /* Update the failed time. */
 120                         fcc->lookup_time = time(NULL);
 121                         return;
 122                 }
 123         }
 124
 125         /* Create negative lookup cache entry for this domain and controller */
 126
 127         if ( !(fcc = SMB_MALLOC_P(struct failed_connection_cache)) ) {
 128                 DEBUG(0, ("malloc failed in add_failed_connection_entry!\n"));
 129                 return;
 130         }
 131
 132         ZERO_STRUCTP(fcc);
 133
 134         fstrcpy( fcc->domain_name, domain );
 135         fstrcpy( fcc->controller, server );
 136         fcc->lookup_time = time(NULL);
 137         fcc->nt_status = result;
 138
 139         DEBUG(10,("add_failed_connection_entry: added domain %s (%s) to failed conn cache\n",
 140                 domain, server ));
 141
 142         DLIST_ADD(failed_connection_cache, fcc);
 143 }
 144
 145 /****************************************************************************
 146 ****************************************************************************/
 147
 148 void flush_negative_conn_cache( void )
 149 {
 150         struct failed_connection_cache *fcc;
 151
 152         fcc = failed_connection_cache;
 153
 154         while (fcc) {
 155                 struct failed_connection_cache *fcc_next;
 156
 157                 fcc_next = fcc->next;
 158                 DLIST_REMOVE(failed_connection_cache, fcc);
 159                 free(fcc);
 160
 161                 fcc = fcc_next;
 162         }
 163
 164 }