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 3 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, see <http://www.gnu.org/licenses/>.
  22 */
  23
  24
  25 #include "includes.h"
  26
  27 #define CONNCACHE_ADDR          1
  28 #define CONNCACHE_NAME          2
  29
  30 /* cache entry contains either a server name **or** and IP address as
  31    the key.  This means that a server could have two entries (one for each key) */
  32
  33 struct failed_connection_cache {
  34         fstring         domain_name;
  35         fstring         controller;
  36         time_t          lookup_time;
  37         NTSTATUS        nt_status;
  38         struct failed_connection_cache *prev, *next;
  39 };
  40
  41 static struct failed_connection_cache *failed_connection_cache;
  42
  43 /**********************************************************************
  44  Check for a previously failed connection.
  45  failed_cache_timeout is an a absolute number of seconds after which
  46  we should time this out. If failed_cache_timeout == 0 then time out
  47  immediately. If failed_cache_timeout == -1 then never time out.
  48 **********************************************************************/
  49
  50 NTSTATUS check_negative_conn_cache_timeout( const char *domain, const char *server, unsigned int failed_cache_timeout )
  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
  66                 /* we have a match so see if it is still current */
  67                 if (failed_cache_timeout != (unsigned int)-1) {
  68                         if (failed_cache_timeout == 0 ||
  69                                         (time(NULL) - fcc->lookup_time) > (time_t)failed_cache_timeout) {
  70                                 /* Cache entry has expired, delete it */
  71
  72                                 DEBUG(10, ("check_negative_conn_cache: cache entry expired for %s, %s\n",
  73                                         domain, server ));
  74
  75                                 DLIST_REMOVE(failed_connection_cache, fcc);
  76                                 SAFE_FREE(fcc);
  77
  78                                 return NT_STATUS_OK;
  79                         }
  80                 }
  81
  82                 /* The timeout hasn't expired yet so return false */
  83
  84                 DEBUG(10, ("check_negative_conn_cache: returning negative entry for %s, %s\n",
  85                         domain, server ));
  86
  87                 result = fcc->nt_status;
  88                 return result;
  89         }
  90
  91         /* end of function means no cache entry */
  92         return NT_STATUS_OK;
  93 }
  94
  95 NTSTATUS check_negative_conn_cache( const char *domain, const char *server)
  96 {
  97         return check_negative_conn_cache_timeout(domain, server, FAILED_CONNECTION_CACHE_TIMEOUT);
  98 }
  99
 100 /**********************************************************************
 101  Add an entry to the failed conneciton cache (aither a name of dotted
 102  decimal IP
 103 **********************************************************************/
 104
 105 void add_failed_connection_entry(const char *domain, const char *server, NTSTATUS result)
 106 {
 107         struct failed_connection_cache *fcc;
 108
 109         SMB_ASSERT(!NT_STATUS_IS_OK(result));
 110
 111         /* Check we already aren't in the cache.  We always have to have
 112            a domain, but maybe not a specific DC name. */
 113
 114         for (fcc = failed_connection_cache; fcc; fcc = fcc->next) {
 115                 if ( strequal(fcc->domain_name, domain) && strequal(fcc->controller, server) ) {
 116                         DEBUG(10, ("add_failed_connection_entry: domain %s (%s) already tried and failed\n",
 117                                    domain, server ));
 118                         /* Update the failed time. */
 119                         fcc->lookup_time = time(NULL);
 120                         return;
 121                 }
 122         }
 123
 124         /* Create negative lookup cache entry for this domain and controller */
 125
 126         if ( !(fcc = SMB_MALLOC_P(struct failed_connection_cache)) ) {
 127                 DEBUG(0, ("malloc failed in add_failed_connection_entry!\n"));
 128                 return;
 129         }
 130
 131         ZERO_STRUCTP(fcc);
 132
 133         fstrcpy( fcc->domain_name, domain );
 134         fstrcpy( fcc->controller, server );
 135         fcc->lookup_time = time(NULL);
 136         fcc->nt_status = result;
 137
 138         DEBUG(10,("add_failed_connection_entry: added domain %s (%s) to failed conn cache\n",
 139                 domain, server ));
 140
 141         DLIST_ADD(failed_connection_cache, fcc);
 142 }
 143
 144 /****************************************************************************
 145 ****************************************************************************/
 146
 147 void flush_negative_conn_cache( void )
 148 {
 149         struct failed_connection_cache *fcc;
 150
 151         fcc = failed_connection_cache;
 152
 153         while (fcc) {
 154                 struct failed_connection_cache *fcc_next;
 155
 156                 fcc_next = fcc->next;
 157                 DLIST_REMOVE(failed_connection_cache, fcc);
 158                 free(fcc);
 159
 160                 fcc = fcc_next;
 161         }
 162
 163 }
 164
 165 /****************************************************************************
 166  Remove all negative entries for a domain. Used when going to online state in
 167  winbindd.
 168 ****************************************************************************/
 169
 170 void flush_negative_conn_cache_for_domain(const char *domain)
 171 {
 172         struct failed_connection_cache *fcc;
 173
 174         fcc = failed_connection_cache;
 175
 176         while (fcc) {
 177                 struct failed_connection_cache *fcc_next;
 178
 179                 fcc_next = fcc->next;
 180
 181                 if (strequal(fcc->domain_name, domain)) {
 182                         DEBUG(10,("flush_negative_conn_cache_for_domain: removed server %s "
 183                                 " from failed cache for domain %s\n",
 184                                 fcc->controller, domain));
 185                         DLIST_REMOVE(failed_connection_cache, fcc);
 186                         free(fcc);
 187                 }
 188
 189                 fcc = fcc_next;
 190         }
 191 }