| 1 | /************************************************* |
| 2 | * Exim - an Internet mail transport agent * |
| 3 | *************************************************/ |
| 4 | |
| 5 | /* |
| 6 | * Exim - CDB database lookup module |
| 7 | * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |
| 8 | * |
| 9 | * Copyright (c) 1998 Nigel Metheringham, Planet Online Ltd |
| 10 | * |
| 11 | * This program is free software; you can redistribute it and/or |
| 12 | * modify it under the terms of the GNU General Public License |
| 13 | * as published by the Free Software Foundation; either version 2 |
| 14 | * of the License, or (at your option) any later version. |
| 15 | * |
| 16 | * -------------------------------------------------------------- |
| 17 | * Modified by PH for Exim 4: |
| 18 | * Changed over to using unsigned chars |
| 19 | * Makes use of lf_check_file() for file checking |
| 20 | * -------------------------------------------------------------- |
| 21 | * Modified by The Exim Maintainers 2015: |
| 22 | * const propagation |
| 23 | * -------------------------------------------------------------- |
| 24 | * |
| 25 | * This program is distributed in the hope that it will be useful, |
| 26 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 27 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 28 | * GNU General Public License for more details. |
| 29 | * |
| 30 | * You should have received a copy of the GNU General Public License |
| 31 | * along with this program; if not, write to the Free Software |
| 32 | * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA |
| 33 | * 02111-1307, USA. |
| 34 | * |
| 35 | * |
| 36 | * This code implements Dan Bernstein's Constant DataBase (cdb) spec. |
| 37 | * Information, the spec and sample code for cdb can be obtained from |
| 38 | * http://www.pobox.com/~djb/cdb.html |
| 39 | * |
| 40 | * This implementation borrows some code from Dan Bernstein's |
| 41 | * implementation (which has no license restrictions applied to it). |
| 42 | * This (read-only) implementation is completely contained within |
| 43 | * cdb.[ch] it does *not* link against an external cdb library. |
| 44 | * |
| 45 | * |
| 46 | * There are 2 variants included within this code. One uses MMAP and |
| 47 | * should give better performance especially for multiple lookups on a |
| 48 | * modern machine. The other is the default implementation which is |
| 49 | * used in the case where the MMAP fails or if MMAP was not compiled |
| 50 | * in. this implementation is the same as the original reference cdb |
| 51 | * implementation. The MMAP version is compiled in if the HAVE_MMAP |
| 52 | * preprocessor define is defined - this should be set in the system |
| 53 | * specific os.h file. |
| 54 | * |
| 55 | */ |
| 56 | |
| 57 | |
| 58 | #include "../exim.h" |
| 59 | #include "lf_functions.h" |
| 60 | |
| 61 | #ifdef HAVE_MMAP |
| 62 | # include <sys/mman.h> |
| 63 | /* Not all implementations declare MAP_FAILED */ |
| 64 | # ifndef MAP_FAILED |
| 65 | # define MAP_FAILED ((void *) -1) |
| 66 | # endif /* MAP_FAILED */ |
| 67 | #endif /* HAVE_MMAP */ |
| 68 | |
| 69 | |
| 70 | #define CDB_HASH_SPLIT 256 /* num pieces the hash table is split into */ |
| 71 | #define CDB_HASH_MASK 255 /* mask to and off split value */ |
| 72 | #define CDB_HASH_ENTRY 8 /* how big each offset it */ |
| 73 | #define CDB_HASH_TABLE (CDB_HASH_SPLIT * CDB_HASH_ENTRY) |
| 74 | |
| 75 | /* State information for cdb databases that are open NB while the db |
| 76 | * is open its contents will not change (cdb dbs are normally updated |
| 77 | * atomically by renaming). However the lifetime of one of these |
| 78 | * state structures should be limited - ie a long running daemon |
| 79 | * that opens one may hit problems.... |
| 80 | */ |
| 81 | |
| 82 | struct cdb_state { |
| 83 | int fileno; |
| 84 | off_t filelen; |
| 85 | uschar *cdb_map; |
| 86 | uschar *cdb_offsets; |
| 87 | }; |
| 88 | |
| 89 | /* 32 bit unsigned type - this is an int on all modern machines */ |
| 90 | typedef unsigned int uint32; |
| 91 | |
| 92 | /* |
| 93 | * cdb_hash() |
| 94 | * Internal function to make hash value */ |
| 95 | |
| 96 | static uint32 |
| 97 | cdb_hash(const uschar *buf, unsigned int len) |
| 98 | { |
| 99 | uint32 h; |
| 100 | |
| 101 | h = 5381; |
| 102 | while (len) { |
| 103 | --len; |
| 104 | h += (h << 5); |
| 105 | h ^= (uint32) *buf++; |
| 106 | } |
| 107 | return h; |
| 108 | } |
| 109 | |
| 110 | /* |
| 111 | * cdb_bread() |
| 112 | * Internal function to read len bytes from disk, coping with oddities */ |
| 113 | |
| 114 | static int |
| 115 | cdb_bread(int fd, |
| 116 | uschar *buf, |
| 117 | int len) |
| 118 | { |
| 119 | int r; |
| 120 | while (len > 0) { |
| 121 | do |
| 122 | r = Uread(fd,buf,len); |
| 123 | while ((r == -1) && (errno == EINTR)); |
| 124 | if (r == -1) return -1; |
| 125 | if (r == 0) { errno = EIO; return -1; } |
| 126 | buf += r; |
| 127 | len -= r; |
| 128 | } |
| 129 | return 0; |
| 130 | } |
| 131 | |
| 132 | /* |
| 133 | * cdb_bread() |
| 134 | * Internal function to parse 4 byte number (endian independent) */ |
| 135 | |
| 136 | static uint32 |
| 137 | cdb_unpack(uschar *buf) |
| 138 | { |
| 139 | uint32 num; |
| 140 | num = buf[3]; num <<= 8; |
| 141 | num += buf[2]; num <<= 8; |
| 142 | num += buf[1]; num <<= 8; |
| 143 | num += buf[0]; |
| 144 | return num; |
| 145 | } |
| 146 | |
| 147 | static void cdb_close(void *handle); |
| 148 | |
| 149 | static void * |
| 150 | cdb_open(uschar *filename, |
| 151 | uschar **errmsg) |
| 152 | { |
| 153 | int fileno; |
| 154 | struct cdb_state *cdbp; |
| 155 | struct stat statbuf; |
| 156 | void * mapbuf; |
| 157 | |
| 158 | fileno = Uopen(filename, O_RDONLY, 0); |
| 159 | if (fileno == -1) { |
| 160 | int save_errno = errno; |
| 161 | *errmsg = string_open_failed(errno, "%s for cdb lookup", filename); |
| 162 | errno = save_errno; |
| 163 | return NULL; |
| 164 | } |
| 165 | |
| 166 | if (fstat(fileno, &statbuf) == 0) { |
| 167 | /* If this is a valid file, then it *must* be at least |
| 168 | * CDB_HASH_TABLE bytes long */ |
| 169 | if (statbuf.st_size < CDB_HASH_TABLE) { |
| 170 | int save_errno = errno; |
| 171 | *errmsg = string_open_failed(errno, |
| 172 | "%s too short for cdb lookup", |
| 173 | filename); |
| 174 | errno = save_errno; |
| 175 | return NULL; |
| 176 | } |
| 177 | } else { |
| 178 | int save_errno = errno; |
| 179 | *errmsg = string_open_failed(errno, |
| 180 | "fstat(%s) failed - cannot do cdb lookup", |
| 181 | filename); |
| 182 | errno = save_errno; |
| 183 | return NULL; |
| 184 | } |
| 185 | |
| 186 | /* Having got a file open we need the structure to put things in */ |
| 187 | cdbp = store_get(sizeof(struct cdb_state)); |
| 188 | /* store_get() does not return if memory was not available... */ |
| 189 | /* preload the structure.... */ |
| 190 | cdbp->fileno = fileno; |
| 191 | cdbp->filelen = statbuf.st_size; |
| 192 | cdbp->cdb_map = NULL; |
| 193 | cdbp->cdb_offsets = NULL; |
| 194 | |
| 195 | /* if we are allowed to we use mmap here.... */ |
| 196 | #ifdef HAVE_MMAP |
| 197 | mapbuf = mmap(NULL, |
| 198 | statbuf.st_size, |
| 199 | PROT_READ, |
| 200 | MAP_SHARED, |
| 201 | fileno, |
| 202 | 0); |
| 203 | if (mapbuf != MAP_FAILED) { |
| 204 | /* We have an mmap-ed section. Now we can just use it */ |
| 205 | cdbp->cdb_map = mapbuf; |
| 206 | /* The offsets can be set to the same value since they should |
| 207 | * effectively be cached as well |
| 208 | */ |
| 209 | cdbp->cdb_offsets = mapbuf; |
| 210 | |
| 211 | /* Now return the state struct */ |
| 212 | return(cdbp); |
| 213 | } else { |
| 214 | /* If we got here the map failed. Basically we can ignore |
| 215 | * this since we fall back to slower methods.... |
| 216 | * However lets debug log it... |
| 217 | */ |
| 218 | DEBUG(D_lookup) debug_printf("cdb mmap failed - %d\n", errno); |
| 219 | } |
| 220 | #endif /* HAVE_MMAP */ |
| 221 | |
| 222 | /* In this case we have either not got MMAP allowed, or it failed */ |
| 223 | |
| 224 | /* get a buffer to stash the basic offsets in - this should speed |
| 225 | * things up a lot - especially on multiple lookups */ |
| 226 | cdbp->cdb_offsets = store_get(CDB_HASH_TABLE); |
| 227 | |
| 228 | /* now fill the buffer up... */ |
| 229 | if (cdb_bread(fileno, cdbp->cdb_offsets, CDB_HASH_TABLE) == -1) { |
| 230 | /* read of hash table failed, oh dear, oh..... |
| 231 | * time to give up I think.... |
| 232 | * call the close routine (deallocs the memory), and return NULL */ |
| 233 | *errmsg = string_open_failed(errno, |
| 234 | "cannot read header from %s for cdb lookup", |
| 235 | filename); |
| 236 | cdb_close(cdbp); |
| 237 | return NULL; |
| 238 | } |
| 239 | |
| 240 | /* Everything else done - return the cache structure */ |
| 241 | return cdbp; |
| 242 | } |
| 243 | |
| 244 | |
| 245 | |
| 246 | /************************************************* |
| 247 | * Check entry point * |
| 248 | *************************************************/ |
| 249 | |
| 250 | static BOOL |
| 251 | cdb_check(void *handle, |
| 252 | uschar *filename, |
| 253 | int modemask, |
| 254 | uid_t *owners, |
| 255 | gid_t *owngroups, |
| 256 | uschar **errmsg) |
| 257 | { |
| 258 | struct cdb_state * cdbp = handle; |
| 259 | return lf_check_file(cdbp->fileno, |
| 260 | filename, |
| 261 | S_IFREG, |
| 262 | modemask, |
| 263 | owners, |
| 264 | owngroups, |
| 265 | "cdb", |
| 266 | errmsg) == 0; |
| 267 | } |
| 268 | |
| 269 | |
| 270 | |
| 271 | /************************************************* |
| 272 | * Find entry point * |
| 273 | *************************************************/ |
| 274 | |
| 275 | static int |
| 276 | cdb_find(void *handle, |
| 277 | uschar *filename, |
| 278 | const uschar *keystring, |
| 279 | int key_len, |
| 280 | uschar **result, |
| 281 | uschar **errmsg, |
| 282 | uint *do_cache) |
| 283 | { |
| 284 | struct cdb_state * cdbp = handle; |
| 285 | uint32 item_key_len, |
| 286 | item_dat_len, |
| 287 | key_hash, |
| 288 | item_hash, |
| 289 | item_posn, |
| 290 | cur_offset, |
| 291 | end_offset, |
| 292 | hash_offset_entry, |
| 293 | hash_offset, |
| 294 | hash_offlen, |
| 295 | hash_slotnm; |
| 296 | int loop; |
| 297 | |
| 298 | /* Keep picky compilers happy */ |
| 299 | do_cache = do_cache; |
| 300 | |
| 301 | key_hash = cdb_hash(keystring, key_len); |
| 302 | |
| 303 | hash_offset_entry = CDB_HASH_ENTRY * (key_hash & CDB_HASH_MASK); |
| 304 | hash_offset = cdb_unpack(cdbp->cdb_offsets + hash_offset_entry); |
| 305 | hash_offlen = cdb_unpack(cdbp->cdb_offsets + hash_offset_entry + 4); |
| 306 | |
| 307 | /* If the offset length is zero this key cannot be in the file */ |
| 308 | |
| 309 | if (hash_offlen == 0) |
| 310 | return FAIL; |
| 311 | |
| 312 | hash_slotnm = (key_hash >> 8) % hash_offlen; |
| 313 | |
| 314 | /* check to ensure that the file is not corrupt |
| 315 | * if the hash_offset + (hash_offlen * CDB_HASH_ENTRY) is longer |
| 316 | * than the file, then we have problems.... */ |
| 317 | |
| 318 | if ((hash_offset + (hash_offlen * CDB_HASH_ENTRY)) > cdbp->filelen) |
| 319 | { |
| 320 | *errmsg = string_sprintf("cdb: corrupt cdb file %s (too short)", |
| 321 | filename); |
| 322 | DEBUG(D_lookup) debug_printf("%s\n", *errmsg); |
| 323 | return DEFER; |
| 324 | } |
| 325 | |
| 326 | cur_offset = hash_offset + (hash_slotnm * CDB_HASH_ENTRY); |
| 327 | end_offset = hash_offset + (hash_offlen * CDB_HASH_ENTRY); |
| 328 | |
| 329 | /* if we are allowed to we use mmap here.... */ |
| 330 | |
| 331 | #ifdef HAVE_MMAP |
| 332 | /* make sure the mmap was OK */ |
| 333 | if (cdbp->cdb_map != NULL) |
| 334 | { |
| 335 | uschar * cur_pos = cur_offset + cdbp->cdb_map; |
| 336 | uschar * end_pos = end_offset + cdbp->cdb_map; |
| 337 | |
| 338 | for (loop = 0; (loop < hash_offlen); ++loop) |
| 339 | { |
| 340 | item_hash = cdb_unpack(cur_pos); |
| 341 | cur_pos += 4; |
| 342 | item_posn = cdb_unpack(cur_pos); |
| 343 | cur_pos += 4; |
| 344 | |
| 345 | /* if the position is zero then we have a definite miss */ |
| 346 | |
| 347 | if (item_posn == 0) |
| 348 | return FAIL; |
| 349 | |
| 350 | if (item_hash == key_hash) |
| 351 | { /* matching hash value */ |
| 352 | uschar * item_ptr = cdbp->cdb_map + item_posn; |
| 353 | |
| 354 | item_key_len = cdb_unpack(item_ptr); |
| 355 | item_ptr += 4; |
| 356 | item_dat_len = cdb_unpack(item_ptr); |
| 357 | item_ptr += 4; |
| 358 | |
| 359 | /* check key length matches */ |
| 360 | |
| 361 | if (item_key_len == key_len) |
| 362 | { |
| 363 | /* finally check if key matches */ |
| 364 | if (Ustrncmp(keystring, item_ptr, key_len) == 0) |
| 365 | { |
| 366 | /* we have a match.... * make item_ptr point to data */ |
| 367 | |
| 368 | item_ptr += item_key_len; |
| 369 | |
| 370 | /* ... and the returned result */ |
| 371 | |
| 372 | *result = store_get(item_dat_len + 1); |
| 373 | memcpy(*result, item_ptr, item_dat_len); |
| 374 | (*result)[item_dat_len] = 0; |
| 375 | return OK; |
| 376 | } |
| 377 | } |
| 378 | } |
| 379 | /* handle warp round of table */ |
| 380 | if (cur_pos == end_pos) |
| 381 | cur_pos = cdbp->cdb_map + hash_offset; |
| 382 | } |
| 383 | /* looks like we failed... */ |
| 384 | return FAIL; |
| 385 | } |
| 386 | |
| 387 | #endif /* HAVE_MMAP */ |
| 388 | |
| 389 | for (loop = 0; (loop < hash_offlen); ++loop) |
| 390 | { |
| 391 | uschar packbuf[8]; |
| 392 | |
| 393 | if (lseek(cdbp->fileno, (off_t) cur_offset, SEEK_SET) == -1) return DEFER; |
| 394 | if (cdb_bread(cdbp->fileno, packbuf, 8) == -1) return DEFER; |
| 395 | |
| 396 | item_hash = cdb_unpack(packbuf); |
| 397 | item_posn = cdb_unpack(packbuf + 4); |
| 398 | |
| 399 | /* if the position is zero then we have a definite miss */ |
| 400 | |
| 401 | if (item_posn == 0) |
| 402 | return FAIL; |
| 403 | |
| 404 | if (item_hash == key_hash) |
| 405 | { /* matching hash value */ |
| 406 | if (lseek(cdbp->fileno, (off_t) item_posn, SEEK_SET) == -1) return DEFER; |
| 407 | if (cdb_bread(cdbp->fileno, packbuf, 8) == -1) return DEFER; |
| 408 | |
| 409 | item_key_len = cdb_unpack(packbuf); |
| 410 | |
| 411 | /* check key length matches */ |
| 412 | |
| 413 | if (item_key_len == key_len) |
| 414 | { /* finally check if key matches */ |
| 415 | uschar * item_key = store_get(key_len); |
| 416 | |
| 417 | if (cdb_bread(cdbp->fileno, item_key, key_len) == -1) return DEFER; |
| 418 | if (Ustrncmp(keystring, item_key, key_len) == 0) { |
| 419 | |
| 420 | /* Reclaim some store */ |
| 421 | store_reset(item_key); |
| 422 | |
| 423 | /* matches - get data length */ |
| 424 | item_dat_len = cdb_unpack(packbuf + 4); |
| 425 | |
| 426 | /* then we build a new result string. We know we have enough |
| 427 | memory so disable Coverity errors about the tainted item_dat_ken */ |
| 428 | |
| 429 | *result = store_get(item_dat_len + 1); |
| 430 | /* coverity[tainted_data] */ |
| 431 | if (cdb_bread(cdbp->fileno, *result, item_dat_len) == -1) |
| 432 | return DEFER; |
| 433 | |
| 434 | /* coverity[tainted_data] */ |
| 435 | (*result)[item_dat_len] = 0; |
| 436 | return OK; |
| 437 | } |
| 438 | /* Reclaim some store */ |
| 439 | store_reset(item_key); |
| 440 | } |
| 441 | } |
| 442 | cur_offset += 8; |
| 443 | |
| 444 | /* handle warp round of table */ |
| 445 | if (cur_offset == end_offset) |
| 446 | cur_offset = hash_offset; |
| 447 | } |
| 448 | return FAIL; |
| 449 | } |
| 450 | |
| 451 | |
| 452 | |
| 453 | /************************************************* |
| 454 | * Close entry point * |
| 455 | *************************************************/ |
| 456 | |
| 457 | /* See local README for interface description */ |
| 458 | |
| 459 | static void |
| 460 | cdb_close(void *handle) |
| 461 | { |
| 462 | struct cdb_state * cdbp = handle; |
| 463 | |
| 464 | #ifdef HAVE_MMAP |
| 465 | if (cdbp->cdb_map) { |
| 466 | munmap(CS cdbp->cdb_map, cdbp->filelen); |
| 467 | if (cdbp->cdb_map == cdbp->cdb_offsets) |
| 468 | cdbp->cdb_offsets = NULL; |
| 469 | } |
| 470 | #endif /* HAVE_MMAP */ |
| 471 | |
| 472 | (void)close(cdbp->fileno); |
| 473 | } |
| 474 | |
| 475 | |
| 476 | |
| 477 | /************************************************* |
| 478 | * Version reporting entry point * |
| 479 | *************************************************/ |
| 480 | |
| 481 | /* See local README for interface description. */ |
| 482 | |
| 483 | #include "../version.h" |
| 484 | |
| 485 | void |
| 486 | cdb_version_report(FILE *f) |
| 487 | { |
| 488 | #ifdef DYNLOOKUP |
| 489 | fprintf(f, "Library version: CDB: Exim version %s\n", EXIM_VERSION_STR); |
| 490 | #endif |
| 491 | } |
| 492 | |
| 493 | |
| 494 | lookup_info cdb_lookup_info = { |
| 495 | US"cdb", /* lookup name */ |
| 496 | lookup_absfile, /* uses absolute file name */ |
| 497 | cdb_open, /* open function */ |
| 498 | cdb_check, /* check function */ |
| 499 | cdb_find, /* find function */ |
| 500 | cdb_close, /* close function */ |
| 501 | NULL, /* no tidy function */ |
| 502 | NULL, /* no quoting function */ |
| 503 | cdb_version_report /* version reporting */ |
| 504 | }; |
| 505 | |
| 506 | #ifdef DYNLOOKUP |
| 507 | #define cdb_lookup_module_info _lookup_module_info |
| 508 | #endif |
| 509 | |
| 510 | static lookup_info *_lookup_list[] = { &cdb_lookup_info }; |
| 511 | lookup_module_info cdb_lookup_module_info = { LOOKUP_MODULE_INFO_MAGIC, _lookup_list, 1 }; |
| 512 | |
| 513 | /* End of lookups/cdb.c */ |