source3/lib/gencache.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3
   4    Generic, persistent and shared between processes cache mechanism for use
   5    by various parts of the Samba code
   6
   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 3 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, see <http://www.gnu.org/licenses/>.
  21 */
  22
  23 #include "includes.h"
  24
  25 #undef  DBGC_CLASS
  26 #define DBGC_CLASS DBGC_TDB
  27
  28 #define TIMEOUT_LEN 12
  29 #define CACHE_DATA_FMT  "%12u/%s"
  30 #define READ_CACHE_DATA_FMT_TEMPLATE "%%12u/%%%us"
  31 #define BLOB_TYPE "DATA_BLOB"
  32 #define BLOB_TYPE_LEN 9
  33
  34 static struct tdb_context *cache;
  35
  36 /**
  37  * @file gencache.c
  38  * @brief Generic, persistent and shared between processes cache mechanism
  39  *        for use by various parts of the Samba code
  40  *
  41  **/
  42
  43
  44 /**
  45  * Cache initialisation function. Opens cache tdb file or creates
  46  * it if does not exist.
  47  *
  48  * @return true on successful initialisation of the cache or
  49  *         false on failure
  50  **/
  51
  52 bool gencache_init(void)
  53 {
  54         char* cache_fname = NULL;
  55
  56         /* skip file open if it's already opened */
  57         if (cache) return True;
  58
  59         cache_fname = lock_path("gencache.tdb");
  60
  61         DEBUG(5, ("Opening cache file at %s\n", cache_fname));
  62
  63         cache = tdb_open_log(cache_fname, 0, TDB_DEFAULT,
  64                              O_RDWR|O_CREAT, 0644);
  65
  66         if (!cache && (errno == EACCES)) {
  67                 cache = tdb_open_log(cache_fname, 0, TDB_DEFAULT, O_RDONLY, 0644);
  68                 if (cache) {
  69                         DEBUG(5, ("gencache_init: Opening cache file %s read-only.\n", cache_fname));
  70                 }
  71         }
  72
  73         if (!cache) {
  74                 DEBUG(5, ("Attempt to open gencache.tdb has failed.\n"));
  75                 return False;
  76         }
  77         return True;
  78 }
  79
  80
  81 /**
  82  * Cache shutdown function. Closes opened cache tdb file.
  83  *
  84  * @return true on successful closing the cache or
  85  *         false on failure during cache shutdown
  86  **/
  87
  88 bool gencache_shutdown(void)
  89 {
  90         int ret;
  91         /* tdb_close routine returns -1 on error */
  92         if (!cache) return False;
  93         DEBUG(5, ("Closing cache file\n"));
  94         ret = tdb_close(cache);
  95         cache = NULL;
  96         return ret != -1;
  97 }
  98
  99
 100 /**
 101  * Set an entry in the cache file. If there's no such
 102  * one, then add it.
 103  *
 104  * @param keystr string that represents a key of this entry
 105  * @param value text representation value being cached
 106  * @param timeout time when the value is expired
 107  *
 108  * @retval true when entry is successfuly stored
 109  * @retval false on failure
 110  **/
 111
 112 bool gencache_set(const char *keystr, const char *value, time_t timeout)
 113 {
 114         int ret;
 115         TDB_DATA databuf;
 116         char* valstr = NULL;
 117
 118         if ((keystr == NULL) || (value == NULL)) {
 119                 return false;
 120         }
 121
 122         if (!gencache_init()) return False;
 123
 124         if (asprintf(&valstr, CACHE_DATA_FMT, (int)timeout, value) == -1) {
 125                 return False;
 126         }
 127
 128         databuf = string_term_tdb_data(valstr);
 129         DEBUG(10, ("Adding cache entry with key = %s; value = %s and timeout ="
 130                    " %s (%d seconds %s)\n", keystr, value,ctime(&timeout),
 131                    (int)(timeout - time(NULL)),
 132                    timeout > time(NULL) ? "ahead" : "in the past"));
 133
 134         ret = tdb_store_bystring(cache, keystr, databuf, 0);
 135         SAFE_FREE(valstr);
 136
 137         return ret == 0;
 138 }
 139
 140 /**
 141  * Delete one entry from the cache file.
 142  *
 143  * @param keystr string that represents a key of this entry
 144  *
 145  * @retval true upon successful deletion
 146  * @retval false in case of failure
 147  **/
 148
 149 bool gencache_del(const char *keystr)
 150 {
 151         int ret;
 152
 153         if (keystr == NULL) {
 154                 return false;
 155         }
 156
 157         if (!gencache_init()) return False;
 158
 159         DEBUG(10, ("Deleting cache entry (key = %s)\n", keystr));
 160         ret = tdb_delete_bystring(cache, keystr);
 161
 162         return ret == 0;
 163 }
 164
 165
 166 /**
 167  * Get existing entry from the cache file.
 168  *
 169  * @param keystr string that represents a key of this entry
 170  * @param valstr buffer that is allocated and filled with the entry value
 171  *        buffer's disposing must be done outside
 172  * @param timeout pointer to a time_t that is filled with entry's
 173  *        timeout
 174  *
 175  * @retval true when entry is successfuly fetched
 176  * @retval False for failure
 177  **/
 178
 179 bool gencache_get(const char *keystr, char **valstr, time_t *timeout)
 180 {
 181         TDB_DATA databuf;
 182         time_t t;
 183         char *endptr;
 184
 185         if (keystr == NULL) {
 186                 return false;
 187         }
 188
 189         if (!gencache_init()) {
 190                 return False;
 191         }
 192
 193         databuf = tdb_fetch_bystring(cache, keystr);
 194
 195         if (databuf.dptr == NULL) {
 196                 DEBUG(10, ("Cache entry with key = %s couldn't be found\n",
 197                            keystr));
 198                 return False;
 199         }
 200
 201         t = strtol((const char *)databuf.dptr, &endptr, 10);
 202
 203         if ((endptr == NULL) || (*endptr != '/')) {
 204                 DEBUG(2, ("Invalid gencache data format: %s\n", databuf.dptr));
 205                 SAFE_FREE(databuf.dptr);
 206                 return False;
 207         }
 208
 209         DEBUG(10, ("Returning %s cache entry: key = %s, value = %s, "
 210                    "timeout = %s", t > time(NULL) ? "valid" :
 211                    "expired", keystr, endptr+1, ctime(&t)));
 212
 213         if (t <= time(NULL)) {
 214
 215                 /* We're expired, delete the entry */
 216                 tdb_delete_bystring(cache, keystr);
 217
 218                 SAFE_FREE(databuf.dptr);
 219                 return False;
 220         }
 221
 222         if (valstr) {
 223                 *valstr = SMB_STRDUP(endptr+1);
 224                 if (*valstr == NULL) {
 225                         SAFE_FREE(databuf.dptr);
 226                         DEBUG(0, ("strdup failed\n"));
 227                         return False;
 228                 }
 229         }
 230
 231         SAFE_FREE(databuf.dptr);
 232
 233         if (timeout) {
 234                 *timeout = t;
 235         }
 236
 237         return True;
 238 }
 239
 240 /**
 241  * Get existing entry from the cache file.
 242  *
 243  * @param keystr string that represents a key of this entry
 244  * @param blob DATA_BLOB that is filled with entry's blob
 245  * @param expired pointer to a bool that indicates whether the entry is expired
 246  *
 247  * @retval true when entry is successfuly fetched
 248  * @retval False for failure
 249  **/
 250
 251 bool gencache_get_data_blob(const char *keystr, DATA_BLOB *blob, bool *expired)
 252 {
 253         TDB_DATA databuf;
 254         time_t t;
 255         char *blob_type;
 256         unsigned char *buf = NULL;
 257         bool ret = False;
 258         fstring valstr;
 259         int buflen = 0, len = 0, blob_len = 0;
 260         unsigned char *blob_buf = NULL;
 261
 262         if (keystr == NULL) {
 263                 return false;
 264         }
 265
 266         if (!gencache_init()) {
 267                 return False;
 268         }
 269
 270         databuf = tdb_fetch_bystring(cache, keystr);
 271         if (!databuf.dptr) {
 272                 DEBUG(10,("Cache entry with key = %s couldn't be found\n",
 273                           keystr));
 274                 return False;
 275         }
 276
 277         buf = (unsigned char *)databuf.dptr;
 278         buflen = databuf.dsize;
 279
 280         len += tdb_unpack(buf+len, buflen-len, "fB",
 281                           &valstr,
 282                           &blob_len, &blob_buf);
 283         if (len == -1) {
 284                 goto out;
 285         }
 286
 287         t = strtol(valstr, &blob_type, 10);
 288
 289         if (strcmp(blob_type+1, BLOB_TYPE) != 0) {
 290                 goto out;
 291         }
 292
 293         DEBUG(10,("Returning %s cache entry: key = %s, "
 294                   "timeout = %s", t > time(NULL) ? "valid" :
 295                   "expired", keystr, ctime(&t)));
 296
 297         if (t <= time(NULL)) {
 298                 /* We're expired */
 299                 if (expired) {
 300                         *expired = True;
 301                 }
 302         }
 303
 304         if (blob) {
 305                 *blob = data_blob(blob_buf, blob_len);
 306                 if (!blob->data) {
 307                         goto out;
 308                 }
 309         }
 310
 311         ret = True;
 312  out:
 313         SAFE_FREE(blob_buf);
 314         SAFE_FREE(databuf.dptr);
 315
 316         return ret;
 317 }
 318
 319 /**
 320  * Set an entry in the cache file. If there's no such
 321  * one, then add it.
 322  *
 323  * @param keystr string that represents a key of this entry
 324  * @param blob DATA_BLOB value being cached
 325  * @param timeout time when the value is expired
 326  *
 327  * @retval true when entry is successfuly stored
 328  * @retval false on failure
 329  **/
 330
 331 bool gencache_set_data_blob(const char *keystr, const DATA_BLOB *blob, time_t timeout)
 332 {
 333         bool ret = False;
 334         int tdb_ret;
 335         TDB_DATA databuf;
 336         char *valstr = NULL;
 337         unsigned char *buf = NULL;
 338         int len = 0, buflen = 0;
 339
 340         if ((keystr == NULL) || (blob == NULL)) {
 341                 return false;
 342         }
 343
 344         if (!gencache_init()) {
 345                 return False;
 346         }
 347
 348         if (asprintf(&valstr, "%12u/%s", (int)timeout, BLOB_TYPE) == -1) {
 349                 return False;
 350         }
 351
 352  again:
 353         len = 0;
 354
 355         len += tdb_pack(buf+len, buflen-len, "fB",
 356                         valstr,
 357                         blob->length, blob->data);
 358
 359         if (len == -1) {
 360                 goto out;
 361         }
 362
 363         if (buflen < len) {
 364                 SAFE_FREE(buf);
 365                 buf = SMB_MALLOC_ARRAY(unsigned char, len);
 366                 if (!buf) {
 367                         goto out;
 368                 }
 369                 buflen = len;
 370                 goto again;
 371         }
 372
 373         databuf = make_tdb_data(buf, len);
 374
 375         DEBUG(10,("Adding cache entry with key = %s; "
 376                   "blob size = %d and timeout = %s"
 377                   "(%d seconds %s)\n", keystr, (int)databuf.dsize,
 378                   ctime(&timeout), (int)(timeout - time(NULL)),
 379                   timeout > time(NULL) ? "ahead" : "in the past"));
 380
 381         tdb_ret = tdb_store_bystring(cache, keystr, databuf, 0);
 382         if (tdb_ret == 0) {
 383                 ret = True;
 384         }
 385
 386  out:
 387         SAFE_FREE(valstr);
 388         SAFE_FREE(buf);
 389
 390         return ret;
 391 }
 392
 393 /**
 394  * Iterate through all entries which key matches to specified pattern
 395  *
 396  * @param fn pointer to the function that will be supplied with each single
 397  *        matching cache entry (key, value and timeout) as an arguments
 398  * @param data void pointer to an arbitrary data that is passed directly to the fn
 399  *        function on each call
 400  * @param keystr_pattern pattern the existing entries' keys are matched to
 401  *
 402  **/
 403
 404 struct gencache_iterate_state {
 405         void (*fn)(const char *key, const char *value, time_t timeout,
 406                    void *priv);
 407         const char *pattern;
 408         void *priv;
 409 };
 410
 411 static int gencache_iterate_fn(struct tdb_context *tdb, TDB_DATA key,
 412                                TDB_DATA value, void *priv)
 413 {
 414         struct gencache_iterate_state *state =
 415                 (struct gencache_iterate_state *)priv;
 416         char *keystr;
 417         char *free_key = NULL;
 418         char *valstr;
 419         char *free_val = NULL;
 420         unsigned long u;
 421         time_t timeout;
 422         char *timeout_endp;
 423
 424         if (key.dptr[key.dsize-1] == '\0') {
 425                 keystr = (char *)key.dptr;
 426         } else {
 427                 /* ensure 0-termination */
 428                 keystr = SMB_STRNDUP((char *)key.dptr, key.dsize);
 429                 free_key = keystr;
 430         }
 431
 432         if ((value.dptr == NULL) || (value.dsize <= TIMEOUT_LEN)) {
 433                 goto done;
 434         }
 435
 436         if (fnmatch(state->pattern, keystr, 0) != 0) {
 437                 goto done;
 438         }
 439
 440         if (value.dptr[value.dsize-1] == '\0') {
 441                 valstr = (char *)value.dptr;
 442         } else {
 443                 /* ensure 0-termination */
 444                 valstr = SMB_STRNDUP((char *)value.dptr, value.dsize);
 445                 free_val = valstr;
 446         }
 447
 448         u = strtoul(valstr, &timeout_endp, 10);
 449
 450         if ((*timeout_endp != '/') || ((timeout_endp-valstr) != TIMEOUT_LEN)) {
 451                 goto done;
 452         }
 453
 454         timeout = u;
 455         timeout_endp += 1;
 456
 457         DEBUG(10, ("Calling function with arguments "
 458                    "(key = %s, value = %s, timeout = %s)\n",
 459                    keystr, timeout_endp, ctime(&timeout)));
 460         state->fn(keystr, timeout_endp, timeout, state->priv);
 461
 462  done:
 463         SAFE_FREE(free_key);
 464         SAFE_FREE(free_val);
 465         return 0;
 466 }
 467
 468 void gencache_iterate(void (*fn)(const char* key, const char *value, time_t timeout, void* dptr),
 469                       void* data, const char* keystr_pattern)
 470 {
 471         struct gencache_iterate_state state;
 472
 473         if ((fn == NULL) || (keystr_pattern == NULL)) {
 474                 return;
 475         }
 476
 477         if (!gencache_init()) return;
 478
 479         DEBUG(5, ("Searching cache keys with pattern %s\n", keystr_pattern));
 480
 481         state.fn = fn;
 482         state.pattern = keystr_pattern;
 483         state.priv = data;
 484         tdb_traverse(cache, gencache_iterate_fn, &state);
 485 }