1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
6 * Exim - CDB database lookup module
7 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
9 * Copyright (c) 1998 Nigel Metheringham, Planet Online Ltd
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.
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:
23 * --------------------------------------------------------------
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.
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
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
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.
46 * There are 2 varients 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
59 #include "lf_functions.h"
62 # include <sys/mman.h>
63 /* Not all implementations declare MAP_FAILED */
65 # define MAP_FAILED ((void *) -1)
66 # endif /* MAP_FAILED */
67 #endif /* HAVE_MMAP */
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)
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....
89 /* 32 bit unsigned type - this is an int on all modern machines */
90 typedef unsigned int uint32
;
94 * Internal function to make hash value */
97 cdb_hash(uschar
*buf
, unsigned int len
)
105 h
^= (uint32
) *buf
++;
112 * Internal function to read len bytes from disk, coping with oddities */
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; }
134 * Internal function to parse 4 byte number (endian independant) */
137 cdb_unpack(uschar
*buf
)
140 num
= buf
[3]; num
<<= 8;
141 num
+= buf
[2]; num
<<= 8;
142 num
+= buf
[1]; num
<<= 8;
147 static void cdb_close(void *handle
);
150 cdb_open(uschar
*filename
,
154 struct cdb_state
*cdbp
;
158 fileno
= Uopen(filename
, O_RDONLY
, 0);
160 int save_errno
= errno
;
161 *errmsg
= string_open_failed(errno
, "%s for cdb lookup", filename
);
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",
178 int save_errno
= errno
;
179 *errmsg
= string_open_failed(errno
,
180 "fstat(%s) failed - cannot do cdb lookup",
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
;
195 /* if we are allowed to we use mmap here.... */
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
209 cdbp
->cdb_offsets
= mapbuf
;
211 /* Now return the state struct */
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...
218 DEBUG(D_lookup
) debug_printf("cdb mmap failed - %d\n", errno
);
220 #endif /* HAVE_MMAP */
222 /* In this case we have either not got MMAP allowed, or it failed */
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
);
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",
240 /* Everything else done - return the cache structure */
246 /*************************************************
247 * Check entry point *
248 *************************************************/
251 cdb_check(void *handle
,
258 struct cdb_state
* cdbp
= handle
;
259 return lf_check_file(cdbp
->fileno
,
271 /*************************************************
273 *************************************************/
276 cdb_find(void *handle
,
278 const uschar
*keystring
,
284 struct cdb_state
* cdbp
= handle
;
298 /* Keep picky compilers happy */
301 key_hash
= cdb_hash((uschar
*)keystring
, key_len
);
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);
307 /* If the offset length is zero this key cannot be in the file */
308 if (hash_offlen
== 0) {
311 hash_slotnm
= (key_hash
>> 8) % hash_offlen
;
313 /* check to ensure that the file is not corrupt
314 * if the hash_offset + (hash_offlen * CDB_HASH_ENTRY) is longer
315 * than the file, then we have problems.... */
316 if ((hash_offset
+ (hash_offlen
* CDB_HASH_ENTRY
)) > cdbp
->filelen
) {
317 *errmsg
= string_sprintf("cdb: corrupt cdb file %s (too short)",
319 DEBUG(D_lookup
) debug_printf("%s\n", *errmsg
);
323 cur_offset
= hash_offset
+ (hash_slotnm
* CDB_HASH_ENTRY
);
324 end_offset
= hash_offset
+ (hash_offlen
* CDB_HASH_ENTRY
);
325 /* if we are allowed to we use mmap here.... */
327 /* make sure the mmap was OK */
328 if (cdbp
->cdb_map
!= NULL
) {
329 uschar
* cur_pos
= cur_offset
+ cdbp
->cdb_map
;
330 uschar
* end_pos
= end_offset
+ cdbp
->cdb_map
;
331 for (loop
= 0; (loop
< hash_offlen
); ++loop
) {
332 item_hash
= cdb_unpack(cur_pos
);
334 item_posn
= cdb_unpack(cur_pos
);
336 /* if the position is zero then we have a definite miss */
340 if (item_hash
== key_hash
) {
341 /* matching hash value */
342 uschar
* item_ptr
= cdbp
->cdb_map
+ item_posn
;
343 item_key_len
= cdb_unpack(item_ptr
);
345 item_dat_len
= cdb_unpack(item_ptr
);
347 /* check key length matches */
348 if (item_key_len
== key_len
) {
349 /* finally check if key matches */
350 if (Ustrncmp(keystring
, item_ptr
, key_len
) == 0) {
351 /* we have a match....
352 * make item_ptr point to data */
353 item_ptr
+= item_key_len
;
354 /* ... and the returned result */
355 *result
= store_get(item_dat_len
+ 1);
356 memcpy(*result
, item_ptr
, item_dat_len
);
357 (*result
)[item_dat_len
] = 0;
362 /* handle warp round of table */
363 if (cur_pos
== end_pos
)
364 cur_pos
= cdbp
->cdb_map
+ hash_offset
;
366 /* looks like we failed... */
369 #endif /* HAVE_MMAP */
370 for (loop
= 0; (loop
< hash_offlen
); ++loop
) {
372 if (lseek(cdbp
->fileno
, (off_t
) cur_offset
,SEEK_SET
) == -1) return DEFER
;
373 if (cdb_bread(cdbp
->fileno
, packbuf
,8) == -1) return DEFER
;
374 item_hash
= cdb_unpack(packbuf
);
375 item_posn
= cdb_unpack(packbuf
+ 4);
376 /* if the position is zero then we have a definite miss */
380 if (item_hash
== key_hash
) {
381 /* matching hash value */
382 if (lseek(cdbp
->fileno
, (off_t
) item_posn
, SEEK_SET
) == -1) return DEFER
;
383 if (cdb_bread(cdbp
->fileno
, packbuf
, 8) == -1) return DEFER
;
384 item_key_len
= cdb_unpack(packbuf
);
385 /* check key length matches */
386 if (item_key_len
== key_len
) {
387 /* finally check if key matches */
388 uschar
* item_key
= store_get(key_len
);
389 if (cdb_bread(cdbp
->fileno
, item_key
, key_len
) == -1) return DEFER
;
390 if (Ustrncmp(keystring
, item_key
, key_len
) == 0) {
391 /* Reclaim some store */
392 store_reset(item_key
);
393 /* matches - get data length */
394 item_dat_len
= cdb_unpack(packbuf
+ 4);
395 /* then we build a new result string */
396 *result
= store_get(item_dat_len
+ 1);
397 if (cdb_bread(cdbp
->fileno
, *result
, item_dat_len
) == -1)
399 (*result
)[item_dat_len
] = 0;
402 /* Reclaim some store */
403 store_reset(item_key
);
408 /* handle warp round of table */
409 if (cur_offset
== end_offset
)
410 cur_offset
= hash_offset
;
417 /*************************************************
418 * Close entry point *
419 *************************************************/
421 /* See local README for interface description */
424 cdb_close(void *handle
)
426 struct cdb_state
* cdbp
= handle
;
430 munmap(CS cdbp
->cdb_map
, cdbp
->filelen
);
431 if (cdbp
->cdb_map
== cdbp
->cdb_offsets
)
432 cdbp
->cdb_offsets
= NULL
;
434 #endif /* HAVE_MMAP */
436 (void)close(cdbp
->fileno
);
441 /*************************************************
442 * Version reporting entry point *
443 *************************************************/
445 /* See local README for interface description. */
447 #include "../version.h"
450 cdb_version_report(FILE *f
)
453 fprintf(f
, "Library version: CDB: Exim version %s\n", EXIM_VERSION_STR
);
458 lookup_info cdb_lookup_info
= {
459 US
"cdb", /* lookup name */
460 lookup_absfile
, /* uses absolute file name */
461 cdb_open
, /* open function */
462 cdb_check
, /* check function */
463 cdb_find
, /* find function */
464 cdb_close
, /* close function */
465 NULL
, /* no tidy function */
466 NULL
, /* no quoting function */
467 cdb_version_report
/* version reporting */
471 #define cdb_lookup_module_info _lookup_module_info
474 static lookup_info
*_lookup_list
[] = { &cdb_lookup_info
};
475 lookup_module_info cdb_lookup_module_info
= { LOOKUP_MODULE_INFO_MAGIC
, _lookup_list
, 1 };
477 /* End of lookups/cdb.c */