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f1e894f3 | 1 | /* $Cambridge: exim/src/src/lookups/cdb.c,v 1.3 2005/06/27 14:29:44 ph10 Exp $ */ |
0756eb3c PH |
2 | |
3 | /************************************************* | |
4 | * Exim - an Internet mail transport agent * | |
5 | *************************************************/ | |
6 | ||
7 | /* | |
8 | * Exim - CDB database lookup module | |
9 | * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | |
10 | * | |
11 | * Copyright (c) 1998 Nigel Metheringham, Planet Online Ltd | |
12 | * | |
13 | * This program is free software; you can redistribute it and/or | |
14 | * modify it under the terms of the GNU General Public License | |
15 | * as published by the Free Software Foundation; either version 2 | |
16 | * of the License, or (at your option) any later version. | |
17 | * | |
18 | * -------------------------------------------------------------- | |
19 | * Modified by PH for Exim 4: | |
20 | * Changed over to using unsigned chars | |
21 | * Makes use of lf_check_file() for file checking | |
22 | * -------------------------------------------------------------- | |
23 | * | |
24 | * This program is distributed in the hope that it will be useful, | |
25 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
26 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
27 | * GNU General Public License for more details. | |
28 | * | |
29 | * You should have received a copy of the GNU General Public License | |
30 | * along with this program; if not, write to the Free Software | |
31 | * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA | |
32 | * 02111-1307, USA. | |
33 | * | |
34 | * | |
35 | * This code implements Dan Bernstein's Constant DataBase (cdb) spec. | |
36 | * Information, the spec and sample code for cdb can be obtained from | |
37 | * http://www.pobox.com/~djb/cdb.html | |
38 | * | |
39 | * This implementation borrows some code from Dan Bernstein's | |
40 | * implementation (which has no license restrictions applied to it). | |
41 | * This (read-only) implementation is completely contained within | |
42 | * cdb.[ch] it does *not* link against an external cdb library. | |
43 | * | |
44 | * | |
45 | * There are 2 varients included within this code. One uses MMAP and | |
46 | * should give better performance especially for multiple lookups on a | |
47 | * modern machine. The other is the default implementation which is | |
48 | * used in the case where the MMAP fails or if MMAP was not compiled | |
49 | * in. this implementation is the same as the original reference cdb | |
50 | * implementation. The MMAP version is compiled in if the HAVE_MMAP | |
51 | * preprocessor define is defined - this should be set in the system | |
52 | * specific os.h file. | |
53 | * | |
54 | */ | |
55 | ||
56 | ||
57 | #include "../exim.h" | |
58 | #include "lf_functions.h" | |
0756eb3c PH |
59 | |
60 | #ifdef HAVE_MMAP | |
61 | # include <sys/mman.h> | |
62 | /* Not all implementations declare MAP_FAILED */ | |
63 | # ifndef MAP_FAILED | |
64 | # define MAP_FAILED ((void *) -1) | |
65 | # endif /* MAP_FAILED */ | |
66 | #endif /* HAVE_MMAP */ | |
67 | ||
68 | ||
69 | #define CDB_HASH_SPLIT 256 /* num pieces the hash table is split into */ | |
70 | #define CDB_HASH_MASK 255 /* mask to and off split value */ | |
71 | #define CDB_HASH_ENTRY 8 /* how big each offset it */ | |
72 | #define CDB_HASH_TABLE (CDB_HASH_SPLIT * CDB_HASH_ENTRY) | |
73 | ||
74 | /* State information for cdb databases that are open NB while the db | |
75 | * is open its contents will not change (cdb dbs are normally updated | |
76 | * atomically by renaming). However the lifetime of one of these | |
77 | * state structures should be limited - ie a long running daemon | |
78 | * that opens one may hit problems.... | |
79 | */ | |
80 | ||
81 | struct cdb_state { | |
82 | int fileno; | |
83 | off_t filelen; | |
84 | uschar *cdb_map; | |
85 | uschar *cdb_offsets; | |
86 | }; | |
87 | ||
88 | /* 32 bit unsigned type - this is an int on all modern machines */ | |
89 | typedef unsigned int uint32; | |
90 | ||
91 | /* | |
92 | * cdb_hash() | |
93 | * Internal function to make hash value */ | |
94 | ||
95 | static uint32 | |
96 | cdb_hash(uschar *buf, unsigned int len) | |
97 | { | |
98 | uint32 h; | |
99 | ||
100 | h = 5381; | |
101 | while (len) { | |
102 | --len; | |
103 | h += (h << 5); | |
104 | h ^= (uint32) *buf++; | |
105 | } | |
106 | return h; | |
107 | } | |
108 | ||
109 | /* | |
110 | * cdb_bread() | |
111 | * Internal function to read len bytes from disk, coping with oddities */ | |
112 | ||
113 | static int | |
114 | cdb_bread(int fd, | |
115 | uschar *buf, | |
116 | int len) | |
117 | { | |
118 | int r; | |
119 | while (len > 0) { | |
120 | do | |
121 | r = Uread(fd,buf,len); | |
122 | while ((r == -1) && (errno == EINTR)); | |
123 | if (r == -1) return -1; | |
124 | if (r == 0) { errno = EIO; return -1; } | |
125 | buf += r; | |
126 | len -= r; | |
127 | } | |
128 | return 0; | |
129 | } | |
130 | ||
131 | /* | |
132 | * cdb_bread() | |
133 | * Internal function to parse 4 byte number (endian independant) */ | |
134 | ||
135 | static uint32 | |
136 | cdb_unpack(uschar *buf) | |
137 | { | |
138 | uint32 num; | |
139 | num = buf[3]; num <<= 8; | |
140 | num += buf[2]; num <<= 8; | |
141 | num += buf[1]; num <<= 8; | |
142 | num += buf[0]; | |
143 | return num; | |
144 | } | |
145 | ||
e6d225ae DW |
146 | static void cdb_close(void *handle); |
147 | ||
148 | static void * | |
0756eb3c PH |
149 | cdb_open(uschar *filename, |
150 | uschar **errmsg) | |
151 | { | |
152 | int fileno; | |
153 | struct cdb_state *cdbp; | |
154 | struct stat statbuf; | |
155 | void * mapbuf; | |
156 | ||
157 | fileno = Uopen(filename, O_RDONLY, 0); | |
158 | if (fileno == -1) { | |
159 | int save_errno = errno; | |
160 | *errmsg = string_open_failed(errno, "%s for cdb lookup", filename); | |
161 | errno = save_errno; | |
162 | return NULL; | |
163 | } | |
164 | ||
165 | if (fstat(fileno, &statbuf) == 0) { | |
166 | /* If this is a valid file, then it *must* be at least | |
167 | * CDB_HASH_TABLE bytes long */ | |
168 | if (statbuf.st_size < CDB_HASH_TABLE) { | |
169 | int save_errno = errno; | |
170 | *errmsg = string_open_failed(errno, | |
0d7eb84a | 171 | "%s too short for cdb lookup", |
0756eb3c PH |
172 | filename); |
173 | errno = save_errno; | |
174 | return NULL; | |
175 | } | |
176 | } else { | |
177 | int save_errno = errno; | |
178 | *errmsg = string_open_failed(errno, | |
179 | "fstat(%s) failed - cannot do cdb lookup", | |
180 | filename); | |
181 | errno = save_errno; | |
182 | return NULL; | |
183 | } | |
184 | ||
185 | /* Having got a file open we need the structure to put things in */ | |
186 | cdbp = store_get(sizeof(struct cdb_state)); | |
187 | /* store_get() does not return if memory was not available... */ | |
188 | /* preload the structure.... */ | |
189 | cdbp->fileno = fileno; | |
190 | cdbp->filelen = statbuf.st_size; | |
191 | cdbp->cdb_map = NULL; | |
192 | cdbp->cdb_offsets = NULL; | |
193 | ||
194 | /* if we are allowed to we use mmap here.... */ | |
195 | #ifdef HAVE_MMAP | |
196 | mapbuf = mmap(NULL, | |
197 | statbuf.st_size, | |
198 | PROT_READ, | |
199 | MAP_SHARED, | |
200 | fileno, | |
201 | 0); | |
202 | if (mapbuf != MAP_FAILED) { | |
203 | /* We have an mmap-ed section. Now we can just use it */ | |
204 | cdbp->cdb_map = mapbuf; | |
205 | /* The offsets can be set to the same value since they should | |
206 | * effectively be cached as well | |
207 | */ | |
208 | cdbp->cdb_offsets = mapbuf; | |
209 | ||
210 | /* Now return the state struct */ | |
211 | return(cdbp); | |
212 | } else { | |
213 | /* If we got here the map failed. Basically we can ignore | |
214 | * this since we fall back to slower methods.... | |
215 | * However lets debug log it... | |
216 | */ | |
217 | DEBUG(D_lookup) debug_printf("cdb mmap failed - %d\n", errno); | |
218 | } | |
219 | #endif /* HAVE_MMAP */ | |
220 | ||
221 | /* In this case we have either not got MMAP allowed, or it failed */ | |
222 | ||
223 | /* get a buffer to stash the basic offsets in - this should speed | |
224 | * things up a lot - especially on multiple lookups */ | |
225 | cdbp->cdb_offsets = store_get(CDB_HASH_TABLE); | |
226 | ||
227 | /* now fill the buffer up... */ | |
228 | if (cdb_bread(fileno, cdbp->cdb_offsets, CDB_HASH_TABLE) == -1) { | |
229 | /* read of hash table failed, oh dear, oh..... | |
230 | * time to give up I think.... | |
231 | * call the close routine (deallocs the memory), and return NULL */ | |
232 | *errmsg = string_open_failed(errno, | |
233 | "cannot read header from %s for cdb lookup", | |
234 | filename); | |
235 | cdb_close(cdbp); | |
236 | return NULL; | |
237 | } | |
238 | ||
239 | /* Everything else done - return the cache structure */ | |
240 | return cdbp; | |
241 | } | |
242 | ||
243 | ||
244 | ||
245 | /************************************************* | |
246 | * Check entry point * | |
247 | *************************************************/ | |
248 | ||
e6d225ae | 249 | static BOOL |
0756eb3c PH |
250 | cdb_check(void *handle, |
251 | uschar *filename, | |
252 | int modemask, | |
253 | uid_t *owners, | |
254 | gid_t *owngroups, | |
255 | uschar **errmsg) | |
256 | { | |
257 | struct cdb_state * cdbp = handle; | |
258 | return lf_check_file(cdbp->fileno, | |
259 | filename, | |
260 | S_IFREG, | |
261 | modemask, | |
262 | owners, | |
263 | owngroups, | |
264 | "cdb", | |
265 | errmsg) == 0; | |
266 | } | |
267 | ||
268 | ||
269 | ||
270 | /************************************************* | |
271 | * Find entry point * | |
272 | *************************************************/ | |
273 | ||
e6d225ae | 274 | static int |
0756eb3c PH |
275 | cdb_find(void *handle, |
276 | uschar *filename, | |
277 | uschar *keystring, | |
278 | int key_len, | |
279 | uschar **result, | |
280 | uschar **errmsg, | |
281 | BOOL *do_cache) | |
282 | { | |
283 | struct cdb_state * cdbp = handle; | |
284 | uint32 item_key_len, | |
285 | item_dat_len, | |
286 | key_hash, | |
287 | item_hash, | |
288 | item_posn, | |
289 | cur_offset, | |
290 | end_offset, | |
291 | hash_offset_entry, | |
292 | hash_offset, | |
293 | hash_offlen, | |
294 | hash_slotnm; | |
295 | int loop; | |
296 | ||
297 | /* Keep picky compilers happy */ | |
298 | do_cache = do_cache; | |
299 | ||
300 | key_hash = cdb_hash((uschar *)keystring, key_len); | |
301 | ||
302 | hash_offset_entry = CDB_HASH_ENTRY * (key_hash & CDB_HASH_MASK); | |
303 | hash_offset = cdb_unpack(cdbp->cdb_offsets + hash_offset_entry); | |
304 | hash_offlen = cdb_unpack(cdbp->cdb_offsets + hash_offset_entry + 4); | |
305 | ||
306 | /* If the offset length is zero this key cannot be in the file */ | |
307 | if (hash_offlen == 0) { | |
308 | return FAIL; | |
309 | } | |
310 | hash_slotnm = (key_hash >> 8) % hash_offlen; | |
311 | ||
312 | /* check to ensure that the file is not corrupt | |
313 | * if the hash_offset + (hash_offlen * CDB_HASH_ENTRY) is longer | |
314 | * than the file, then we have problems.... */ | |
315 | if ((hash_offset + (hash_offlen * CDB_HASH_ENTRY)) > cdbp->filelen) { | |
316 | *errmsg = string_sprintf("cdb: corrupt cdb file %s (too short)", | |
317 | filename); | |
318 | DEBUG(D_lookup) debug_printf("%s\n", *errmsg); | |
319 | return DEFER; | |
320 | } | |
321 | ||
322 | cur_offset = hash_offset + (hash_slotnm * CDB_HASH_ENTRY); | |
323 | end_offset = hash_offset + (hash_offlen * CDB_HASH_ENTRY); | |
324 | /* if we are allowed to we use mmap here.... */ | |
325 | #ifdef HAVE_MMAP | |
326 | /* make sure the mmap was OK */ | |
327 | if (cdbp->cdb_map != NULL) { | |
328 | uschar * cur_pos = cur_offset + cdbp->cdb_map; | |
329 | uschar * end_pos = end_offset + cdbp->cdb_map; | |
330 | for (loop = 0; (loop < hash_offlen); ++loop) { | |
331 | item_hash = cdb_unpack(cur_pos); | |
332 | cur_pos += 4; | |
333 | item_posn = cdb_unpack(cur_pos); | |
334 | cur_pos += 4; | |
335 | /* if the position is zero then we have a definite miss */ | |
336 | if (item_posn == 0) | |
337 | return FAIL; | |
338 | ||
339 | if (item_hash == key_hash) { | |
340 | /* matching hash value */ | |
341 | uschar * item_ptr = cdbp->cdb_map + item_posn; | |
342 | item_key_len = cdb_unpack(item_ptr); | |
343 | item_ptr += 4; | |
344 | item_dat_len = cdb_unpack(item_ptr); | |
345 | item_ptr += 4; | |
346 | /* check key length matches */ | |
347 | if (item_key_len == key_len) { | |
348 | /* finally check if key matches */ | |
349 | if (Ustrncmp(keystring, item_ptr, key_len) == 0) { | |
350 | /* we have a match.... | |
351 | * make item_ptr point to data */ | |
352 | item_ptr += item_key_len; | |
353 | /* ... and the returned result */ | |
354 | *result = store_get(item_dat_len + 1); | |
355 | memcpy(*result, item_ptr, item_dat_len); | |
356 | (*result)[item_dat_len] = 0; | |
357 | return OK; | |
358 | } | |
359 | } | |
360 | } | |
361 | /* handle warp round of table */ | |
362 | if (cur_pos == end_pos) | |
363 | cur_pos = cdbp->cdb_map + hash_offset; | |
364 | } | |
365 | /* looks like we failed... */ | |
366 | return FAIL; | |
367 | } | |
368 | #endif /* HAVE_MMAP */ | |
369 | for (loop = 0; (loop < hash_offlen); ++loop) { | |
370 | uschar packbuf[8]; | |
371 | if (lseek(cdbp->fileno, (off_t) cur_offset,SEEK_SET) == -1) return DEFER; | |
372 | if (cdb_bread(cdbp->fileno, packbuf,8) == -1) return DEFER; | |
373 | item_hash = cdb_unpack(packbuf); | |
374 | item_posn = cdb_unpack(packbuf + 4); | |
375 | /* if the position is zero then we have a definite miss */ | |
376 | if (item_posn == 0) | |
377 | return FAIL; | |
378 | ||
379 | if (item_hash == key_hash) { | |
380 | /* matching hash value */ | |
381 | if (lseek(cdbp->fileno, (off_t) item_posn, SEEK_SET) == -1) return DEFER; | |
382 | if (cdb_bread(cdbp->fileno, packbuf, 8) == -1) return DEFER; | |
383 | item_key_len = cdb_unpack(packbuf); | |
384 | /* check key length matches */ | |
385 | if (item_key_len == key_len) { | |
386 | /* finally check if key matches */ | |
387 | uschar * item_key = store_get(key_len); | |
388 | if (cdb_bread(cdbp->fileno, item_key, key_len) == -1) return DEFER; | |
389 | if (Ustrncmp(keystring, item_key, key_len) == 0) { | |
390 | /* Reclaim some store */ | |
391 | store_reset(item_key); | |
392 | /* matches - get data length */ | |
393 | item_dat_len = cdb_unpack(packbuf + 4); | |
394 | /* then we build a new result string */ | |
395 | *result = store_get(item_dat_len + 1); | |
396 | if (cdb_bread(cdbp->fileno, *result, item_dat_len) == -1) | |
397 | return DEFER; | |
398 | (*result)[item_dat_len] = 0; | |
399 | return OK; | |
400 | } | |
401 | /* Reclaim some store */ | |
402 | store_reset(item_key); | |
403 | } | |
404 | } | |
405 | cur_offset += 8; | |
406 | ||
407 | /* handle warp round of table */ | |
408 | if (cur_offset == end_offset) | |
409 | cur_offset = hash_offset; | |
410 | } | |
411 | return FAIL; | |
412 | } | |
413 | ||
414 | ||
415 | ||
416 | /************************************************* | |
417 | * Close entry point * | |
418 | *************************************************/ | |
419 | ||
420 | /* See local README for interface description */ | |
421 | ||
e6d225ae | 422 | static void |
0756eb3c PH |
423 | cdb_close(void *handle) |
424 | { | |
425 | struct cdb_state * cdbp = handle; | |
426 | ||
427 | #ifdef HAVE_MMAP | |
428 | if (cdbp->cdb_map) { | |
429 | munmap(CS cdbp->cdb_map, cdbp->filelen); | |
430 | if (cdbp->cdb_map == cdbp->cdb_offsets) | |
431 | cdbp->cdb_offsets = NULL; | |
432 | } | |
433 | #endif /* HAVE_MMAP */ | |
434 | ||
f1e894f3 | 435 | (void)close(cdbp->fileno); |
0756eb3c PH |
436 | } |
437 | ||
6545de78 PP |
438 | |
439 | ||
440 | /************************************************* | |
441 | * Version reporting entry point * | |
442 | *************************************************/ | |
443 | ||
444 | /* See local README for interface description. */ | |
445 | ||
446 | #include "../version.h" | |
447 | ||
448 | void | |
449 | cdb_version_report(FILE *f) | |
450 | { | |
451 | #ifdef DYNLOOKUP | |
452 | fprintf(f, "Library version: CDB: Exim version %s\n", EXIM_VERSION_STR); | |
453 | #endif | |
454 | } | |
455 | ||
456 | ||
e6d225ae DW |
457 | lookup_info cdb_lookup_info = { |
458 | US"cdb", /* lookup name */ | |
459 | lookup_absfile, /* uses absolute file name */ | |
460 | cdb_open, /* open function */ | |
461 | cdb_check, /* check function */ | |
462 | cdb_find, /* find function */ | |
463 | cdb_close, /* close function */ | |
464 | NULL, /* no tidy function */ | |
6545de78 PP |
465 | NULL, /* no quoting function */ |
466 | cdb_version_report /* version reporting */ | |
e6d225ae DW |
467 | }; |
468 | ||
469 | #ifdef DYNLOOKUP | |
470 | #define cdb_lookup_module_info _lookup_module_info | |
471 | #endif | |
472 | ||
473 | static lookup_info *_lookup_list[] = { &cdb_lookup_info }; | |
474 | lookup_module_info cdb_lookup_module_info = { LOOKUP_MODULE_INFO_MAGIC, _lookup_list, 1 }; | |
475 | ||
0756eb3c | 476 | /* End of lookups/cdb.c */ |