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    Copyright (C) Marc VanHeyningen      2008
  10    Copyright (C) Volker Lendecke        2009
  11
  12    This program is free software; you can redistribute it and/or modify
  13    it under the terms of the GNU General Public License as published by
  14    the Free Software Foundation; either version 3 of the License, or
  15    (at your option) any later version.
  16
  17    This program is distributed in the hope that it will be useful,
  18    but WITHOUT ANY WARRANTY; without even the implied warranty of
  19    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20    GNU General Public License for more details.
  21
  22    You should have received a copy of the GNU General Public License
  23    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  24 */
  25
  26
  27 #include "includes.h"
  28
  29 /**
  30  * @file
  31  * Negative connection cache implemented in terms of gencache API
  32  *
  33  * The negative connection cache stores names of servers which have
  34  * been unresponsive so that we don't waste time repeatedly trying
  35  * to contact them.  It used to use an in-memory linked list, but
  36  * this limited its utility to a single process
  37  */
  38
  39
  40 /**
  41  * Marshalls the domain and server name into the key for the gencache
  42  * record
  43  *
  44  * @param[in] domain required
  45  * @param[in] server may be a FQDN or an IP address
  46  * @return the resulting string, which the caller is responsible for
  47  *   SAFE_FREE()ing
  48  * @retval NULL returned on error
  49  */
  50 static char *negative_conn_cache_keystr(const char *domain, const char *server)
  51 {
  52         char *keystr = NULL;
  53
  54         if (domain == NULL) {
  55                 return NULL;
  56         }
  57         if (server == NULL)
  58                 server = "";
  59
  60         keystr = talloc_asprintf(talloc_tos(), "NEG_CONN_CACHE/%s,%s",
  61                                  domain, server);
  62         if (keystr == NULL) {
  63                 DEBUG(0, ("negative_conn_cache_keystr: malloc error\n"));
  64         }
  65
  66         return keystr;
  67 }
  68
  69 /**
  70  * Marshalls the NT status into a printable value field for the gencache
  71  * record
  72  *
  73  * @param[in] status
  74  * @return the resulting string, which the caller is responsible for
  75  *   SAFE_FREE()ing
  76  * @retval NULL returned on error
  77  */
  78 static char *negative_conn_cache_valuestr(NTSTATUS status)
  79 {
  80         char *valuestr = NULL;
  81
  82         valuestr = talloc_asprintf(talloc_tos(), "%x", NT_STATUS_V(status));
  83         if (valuestr == NULL) {
  84                 DEBUG(0, ("negative_conn_cache_valuestr: malloc error\n"));
  85         }
  86
  87         return valuestr;
  88 }
  89
  90 /**
  91  * Un-marshalls the NT status from a printable field for the gencache
  92  * record
  93  *
  94  * @param[in] value  The value field from the record
  95  * @return the decoded NT status
  96  * @retval NT_STATUS_OK returned on error
  97  */
  98 static NTSTATUS negative_conn_cache_valuedecode(const char *value)
  99 {
 100         unsigned int v = NT_STATUS_V(NT_STATUS_INTERNAL_ERROR);
 101
 102         if (value == NULL) {
 103                 return NT_STATUS_INTERNAL_ERROR;
 104         }
 105         if (sscanf(value, "%x", &v) != 1) {
 106                 DEBUG(0, ("negative_conn_cache_valuedecode: unable to parse "
 107                           "value field '%s'\n", value));
 108         }
 109         return NT_STATUS(v);
 110 }
 111
 112 /**
 113  * Function passed to gencache_iterate to remove any matching items
 114  * from the list
 115  *
 116  * @param[in] key Key to the record found and to be deleted
 117  * @param[in] value Value to the record (ignored)
 118  * @param[in] timeout Timeout remaining for the record (ignored)
 119  * @param[in] dptr Handle for passing additional data (ignored)
 120  */
 121 static void delete_matches(const char *key, const char *value,
 122     time_t timeout, void *dptr)
 123 {
 124         gencache_del(key);
 125 }
 126
 127
 128 /**
 129  * Checks for a given domain/server record in the negative cache
 130  *
 131  * @param[in] domain
 132  * @param[in] server may be either a FQDN or an IP address
 133  * @return The cached failure status
 134  * @retval NT_STATUS_OK returned if no record is found or an error occurs
 135  */
 136 NTSTATUS check_negative_conn_cache( const char *domain, const char *server)
 137 {
 138         NTSTATUS result = NT_STATUS_OK;
 139         char *key = NULL;
 140         char *value = NULL;
 141
 142         key = negative_conn_cache_keystr(domain, server);
 143         if (key == NULL)
 144                 goto done;
 145
 146         if (gencache_get(key, &value, NULL))
 147                 result = negative_conn_cache_valuedecode(value);
 148  done:
 149         DEBUG(9,("check_negative_conn_cache returning result %d for domain %s "
 150                   "server %s\n", NT_STATUS_V(result), domain, server));
 151         TALLOC_FREE(key);
 152         SAFE_FREE(value);
 153         return result;
 154 }
 155
 156 /**
 157  * Add an entry to the failed connection cache
 158  *
 159  * @param[in] domain
 160  * @param[in] server may be a FQDN or an IP addr in printable form
 161  * @param[in] result error to cache; must not be NT_STATUS_OK
 162  */
 163 void add_failed_connection_entry(const char *domain, const char *server,
 164     NTSTATUS result)
 165 {
 166         char *key = NULL;
 167         char *value = NULL;
 168
 169         if (NT_STATUS_IS_OK(result)) {
 170                 /* Nothing failed here */
 171                 return;
 172         }
 173
 174         key = negative_conn_cache_keystr(domain, server);
 175         if (key == NULL) {
 176                 DEBUG(0, ("add_failed_connection_entry: key creation error\n"));
 177                 goto done;
 178         }
 179
 180         value = negative_conn_cache_valuestr(result);
 181         if (value == NULL) {
 182                 DEBUG(0, ("add_failed_connection_entry: value creation error\n"));
 183                 goto done;
 184         }
 185
 186         if (gencache_set(key, value,
 187                          time(NULL) + FAILED_CONNECTION_CACHE_TIMEOUT))
 188                 DEBUG(9,("add_failed_connection_entry: added domain %s (%s) "
 189                           "to failed conn cache\n", domain, server ));
 190         else
 191                 DEBUG(1,("add_failed_connection_entry: failed to add "
 192                           "domain %s (%s) to failed conn cache\n",
 193                           domain, server));
 194
 195  done:
 196         TALLOC_FREE(key);
 197         TALLOC_FREE(value);
 198         return;
 199 }
 200
 201 /**
 202  * Deletes all records for a specified domain from the negative connection
 203  * cache
 204  *
 205  * @param[in] domain String to match against domain portion of keys, or "*"
 206  *  to match all domains
 207  */
 208 void flush_negative_conn_cache_for_domain(const char *domain)
 209 {
 210         char *key_pattern = NULL;
 211
 212         key_pattern = negative_conn_cache_keystr(domain,"*");
 213         if (key_pattern == NULL) {
 214                 DEBUG(0, ("flush_negative_conn_cache_for_domain: "
 215                           "key creation error\n"));
 216                 goto done;
 217         }
 218
 219         gencache_iterate(delete_matches, NULL, key_pattern);
 220         DEBUG(8, ("flush_negative_conn_cache_for_domain: flushed domain %s\n",
 221                   domain));
 222
 223  done:
 224         TALLOC_FREE(key_pattern);
 225         return;
 226 }