source/libsmb/namecache.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3
   4    NetBIOS name cache module on top of gencache mechanism.
   5
   6    Copyright (C) Tim Potter         2002
   7    Copyright (C) Rafal Szczesniak   2002
   8
   9    This program is free software; you can redistribute it and/or modify
  10    it under the terms of the GNU General Public License as published by
  11    the Free Software Foundation; either version 2 of the License, or
  12    (at your option) any later version.
  13
  14    This program is distributed in the hope that it will be useful,
  15    but WITHOUT ANY WARRANTY; without even the implied warranty of
  16    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17    GNU General Public License for more details.
  18
  19    You should have received a copy of the GNU General Public License
  20    along with this program; if not, write to the Free Software
  21    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  22 */
  23
  24 #include "includes.h"
  25
  26 #define NBTKEY_FMT  "NBT/%s#%02X"
  27
  28
  29 /**
  30  * Initialise namecache system. Function calls gencache
  31  * initialisation function to perform necessary actions
  32  *
  33  * @return true upon successful initialisation of the cache or
  34  *         false on failure
  35  **/
  36
  37 BOOL namecache_enable(void)
  38 {
  39         /*
  40          * Check if name caching disabled by setting the name cache
  41          * timeout to zero.
  42          */
  43
  44         if (lp_name_cache_timeout() == 0) {
  45                 DEBUG(5, ("namecache_enable: disabling netbios name cache\n"));
  46                 return False;
  47         }
  48
  49         /* Init namecache by calling gencache initialisation */
  50
  51         if (!gencache_init()) {
  52                 DEBUG(2, ("namecache_enable: Couldn't initialise namecache on top of gencache.\n"));
  53                 return False;
  54         }
  55
  56         /* I leave it for now, though I don't think we really need this (mimir, 27.09.2002) */
  57         DEBUG(5, ("namecache_enable: enabling netbios namecache, timeout %d "
  58                   "seconds\n", lp_name_cache_timeout()));
  59
  60         return True;
  61 }
  62
  63
  64 /**
  65  * Shutdown namecache. Routine calls gencache close function
  66  * to safely close gencache file.
  67  *
  68  * @return true upon successful shutdown of the cache or
  69  *         false on failure
  70  **/
  71
  72 BOOL namecache_shutdown(void)
  73 {
  74         if (!gencache_shutdown()) {
  75                 DEBUG(2, ("namecache_shutdown: Couldn't close namecache on top of gencache.\n"));
  76                 return False;
  77         }
  78
  79         DEBUG(5, ("namecache_shutdown: netbios namecache closed successfully.\n"));
  80         return True;
  81 }
  82
  83
  84 /**
  85  * Generates a key for netbios name lookups on basis of
  86  * netbios name and type.
  87  * The caller must free returned key string when finished.
  88  *
  89  * @param name netbios name string (case insensitive)
  90  * @param name_type netbios type of the name being looked up
  91  *
  92  * @return string consisted of uppercased name and appended
  93  *         type number
  94  */
  95
  96 static char* namecache_key(const char *name, int name_type)
  97 {
  98         char *keystr;
  99         asprintf(&keystr, NBTKEY_FMT, strupper_static(name), name_type);
 100
 101         return keystr;
 102 }
 103
 104
 105 /**
 106  * Store a name(s) in the name cache
 107  *
 108  * @param name netbios names array
 109  * @param name_type integer netbios name type
 110  * @param num_names number of names being stored
 111  * @param ip_list array of in_addr structures containing
 112  *        ip addresses being stored
 113  **/
 114
 115 BOOL namecache_store(const char *name, int name_type,
 116                      int num_names, struct in_addr *ip_list)
 117 {
 118         time_t expiry;
 119         char *key, *value_string;
 120         int i;
 121
 122         /*
 123          * we use gecache call to avoid annoying debug messages about
 124          * initialised namecache again and again...
 125          */
 126         if (!gencache_init()) return False;
 127
 128         DEBUG(5, ("namecache_store: storing %d address%s for %s#%02x: ",
 129                   num_names, num_names == 1 ? "": "es", name, name_type));
 130
 131         for (i = 0; i < num_names; i++)
 132                 DEBUGADD(5, ("%s%s", inet_ntoa(ip_list[i]),
 133                              i == (num_names - 1) ? "" : ", "));
 134
 135         DEBUGADD(5, ("\n"));
 136
 137         key = namecache_key(name, name_type);
 138
 139         /*
 140          * Cache pdc location or dc lists for only a little while
 141          * otherwise if we lock on to a bad DC we can potentially be
 142          * out of action for the entire cache timeout time!
 143          */
 144
 145         if (name_type == 0x1b || name_type == 0x1c)
 146                 expiry = time(NULL) + 10;
 147         else
 148                 expiry = time(NULL) + lp_name_cache_timeout();
 149
 150         /*
 151          * Generate string representation of ip addresses list
 152          * First, store the number of ip addresses and then
 153          * place each single ip
 154          */
 155         ipstr_list_make(&value_string, ip_list, num_names);
 156
 157         /* set the entry */
 158         return (gencache_set(key, value_string, expiry));
 159 }
 160
 161
 162 /**
 163  * Look up a name in the cache.
 164  *
 165  * @param name netbios name to look up for
 166  * @param name_type netbios name type of @param name
 167  * @param ip_list mallocated list of IP addresses if found in the cache,
 168  *        NULL otherwise
 169  * @param num_names number of entries found
 170  *
 171  * @return true upon successful fetch or
 172  *         false if name isn't found in the cache or has expired
 173  **/
 174
 175 BOOL namecache_fetch(const char *name, int name_type, struct in_addr **ip_list,
 176                      int *num_names)
 177 {
 178         char *key, *value;
 179         time_t timeout;
 180
 181         *num_names = 0;
 182
 183         /* exit now if null pointers were passed as they're required further */
 184         if (!ip_list || !num_names) return False;
 185
 186         if (!gencache_init())
 187                 return False;
 188
 189         /*
 190          * Use gencache interface - lookup the key
 191          */
 192         key = namecache_key(name, name_type);
 193
 194         if (!gencache_get(key, &value, &timeout)) {
 195                 DEBUG(5, ("no entry for %s#%02X found.\n", name, name_type));
 196                 SAFE_FREE(key);
 197                 return False;
 198         } else {
 199                 DEBUG(5, ("name %s#%02X found.\n", name, name_type));
 200         }
 201
 202         /*
 203          * Split up the stored value into the list of IP adresses
 204          */
 205         *num_names = ipstr_list_parse(value, ip_list);
 206
 207         SAFE_FREE(key);
 208         SAFE_FREE(value);
 209         return *num_names > 0;          /* true only if some ip has been fetched */
 210 }
 211
 212
 213 /**
 214  * Delete single namecache entry. Look at the
 215  * gencache_iterate definition.
 216  *
 217  **/
 218
 219 static void flush_netbios_name(const char* key, const char *value, time_t timeout, void* dptr)
 220 {
 221         gencache_del(key);
 222         DEBUG(5, ("Deleting entry %s\n", key));
 223 }
 224
 225
 226 /**
 227  * Flush all names from the name cache.
 228  * It's done by gencache_iterate()
 229  *
 230  * @return True upon successful deletion or
 231  *         False in case of an error
 232  **/
 233
 234 void namecache_flush(void)
 235 {
 236         if (!gencache_init())
 237                 return;
 238
 239         /*
 240          * iterate through each NBT cache's entry and flush it
 241          * by flush_netbios_name function
 242          */
 243         gencache_iterate(flush_netbios_name, NULL, "NBT/*");
 244         DEBUG(5, ("Namecache flushed\n"));
 245 }
 246