1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
5 /* Copyright (c) University of Cambridge 1995 - 2009 */
6 /* See the file NOTICE for conditions of use and distribution. */
12 /* Functions for accessing Exim's hints database, which consists of a number of
13 different DBM files. This module does not contain code for reading DBM files
14 for (e.g.) alias expansion. That is all contained within the general search
15 functions. As Exim now has support for several DBM interfaces, all the relevant
16 functions are called as macros.
18 All the data in Exim's database is in the nature of *hints*. Therefore it
19 doesn't matter if it gets destroyed by accident. These functions are not
20 supposed to implement a "safe" database.
22 Keys are passed in as C strings, and the terminating zero *is* used when
23 building the dbm files. This just makes life easier when scanning the files
26 Synchronization is required on the database files, and this is achieved by
27 means of locking on independent lock files. (Earlier attempts to lock on the
28 DBM files themselves were never completely successful.) Since callers may in
29 general want to do more than one read or write while holding the lock, there
30 are separate open and close functions. However, the calling modules should
31 arrange to hold the locks for the bare minimum of time. */
35 /*************************************************
36 * Berkeley DB error callback *
37 *************************************************/
39 /* For Berkeley DB >= 2, we can define a function to be called in case of DB
40 errors. This should help with debugging strange DB problems, e.g. getting "File
41 exists" when you try to open a db file. The API for this function was changed
44 #if defined(USE_DB) && defined(DB_VERSION_STRING)
46 #if DB_VERSION_MAJOR > 4 || (DB_VERSION_MAJOR == 4 && DB_VERSION_MINOR >= 3)
47 dbfn_bdb_error_callback(const DB_ENV *dbenv, const char *pfx, const char *msg)
51 dbfn_bdb_error_callback(const char *pfx, char *msg)
55 log_write(0, LOG_MAIN, "Berkeley DB error: %s", msg);
62 /*************************************************
63 * Open and lock a database file *
64 *************************************************/
66 /* Used for accessing Exim's hints databases.
69 name The single-component name of one of Exim's database files.
70 flags Either O_RDONLY or O_RDWR, indicating the type of open required;
71 O_RDWR implies "create if necessary"
72 dbblock Points to an open_db block to be filled in.
73 lof If TRUE, write to the log for actual open failures (locking failures
76 Returns: NULL if the open failed, or the locking failed. After locking
77 failures, errno is zero.
79 On success, dbblock is returned. This contains the dbm pointer and
80 the fd of the locked lock file.
82 There are some calls that use O_RDWR|O_CREAT for the flags. Having discovered
83 this in December 2005, I'm not sure if this is correct or not, but for the
84 moment I haven't changed them.
88 dbfn_open(uschar *name, int flags, open_db *dbblock, BOOL lof)
91 BOOL read_only = flags == O_RDONLY;
96 /* The first thing to do is to open a separate file on which to lock. This
97 ensures that Exim has exclusive use of the database before it even tries to
98 open it. Early versions tried to lock on the open database itself, but that
99 gave rise to mysterious problems from time to time - it was suspected that some
100 DB libraries "do things" on their open() calls which break the interlocking.
101 The lock file is never written to, but we open it for writing so we can get a
102 write lock if required. If it does not exist, we create it. This is done
103 separately so we know when we have done it, because when running as root we
104 need to change the ownership - see the bottom of this function. We also try to
105 make the directory as well, just in case. We won't be doing this many times
106 unnecessarily, because usually the lock file will be there. If the directory
107 exists, there is no error. */
109 sprintf(CS buffer, "%s/db/%s.lockfile", spool_directory, name);
111 if ((dbblock->lockfd = Uopen(buffer, O_RDWR, EXIMDB_LOCKFILE_MODE)) < 0)
114 (void)directory_make(spool_directory, US"db", EXIMDB_DIRECTORY_MODE, TRUE);
115 dbblock->lockfd = Uopen(buffer, O_RDWR|O_CREAT, EXIMDB_LOCKFILE_MODE);
118 if (dbblock->lockfd < 0)
120 log_write(0, LOG_MAIN, "%s",
121 string_open_failed(errno, "database lock file %s", buffer));
122 errno = 0; /* Indicates locking failure */
126 /* Now we must get a lock on the opened lock file; do this with a blocking
127 lock that times out. */
129 lock_data.l_type = read_only? F_RDLCK : F_WRLCK;
130 lock_data.l_whence = lock_data.l_start = lock_data.l_len = 0;
132 DEBUG(D_hints_lookup|D_retry|D_route|D_deliver)
133 debug_printf("locking %s\n", buffer);
135 sigalrm_seen = FALSE;
136 alarm(EXIMDB_LOCK_TIMEOUT);
137 rc = fcntl(dbblock->lockfd, F_SETLKW, &lock_data);
140 if (sigalrm_seen) errno = ETIMEDOUT;
143 log_write(0, LOG_MAIN|LOG_PANIC, "Failed to get %s lock for %s: %s",
144 read_only? "read" : "write", buffer,
145 (errno == ETIMEDOUT)? "timed out" : strerror(errno));
146 (void)close(dbblock->lockfd);
147 errno = 0; /* Indicates locking failure */
151 DEBUG(D_hints_lookup) debug_printf("locked %s\n", buffer);
153 /* At this point we have an opened and locked separate lock file, that is,
154 exclusive access to the database, so we can go ahead and open it. If we are
155 expected to create it, don't do so at first, again so that we can detect
156 whether we need to change its ownership (see comments about the lock file
157 above.) There have been regular reports of crashes while opening hints
158 databases - often this is caused by non-matching db.h and the library. To make
159 it easy to pin this down, there are now debug statements on either side of the
162 sprintf(CS buffer, "%s/db/%s", spool_directory, name);
163 DEBUG(D_hints_lookup) debug_printf("EXIM_DBOPEN(%s)\n", buffer);
164 EXIM_DBOPEN(buffer, flags, EXIMDB_MODE, &(dbblock->dbptr));
165 DEBUG(D_hints_lookup) debug_printf("returned from EXIM_DBOPEN\n");
167 if (dbblock->dbptr == NULL && errno == ENOENT && flags == O_RDWR)
169 DEBUG(D_hints_lookup)
170 debug_printf("%s appears not to exist: trying to create\n", buffer);
172 EXIM_DBOPEN(buffer, flags|O_CREAT, EXIMDB_MODE, &(dbblock->dbptr));
173 DEBUG(D_hints_lookup) debug_printf("returned from EXIM_DBOPEN\n");
178 /* If we are running as root and this is the first access to the database, its
179 files will be owned by root. We want them to be owned by exim. We detect this
180 situation by noting above when we had to create the lock file or the database
181 itself. Because the different dbm libraries use different extensions for their
182 files, I don't know of any easier way of arranging this than scanning the
183 directory for files with the appropriate base name. At least this deals with
184 the lock file at the same time. Also, the directory will typically have only
185 half a dozen files, so the scan will be quick.
187 This code is placed here, before the test for successful opening, because there
188 was a case when a file was created, but the DBM library still returned NULL
189 because of some problem. It also sorts out the lock file if that was created
190 but creation of the database file failed. */
192 if (created && geteuid() == root_uid)
196 uschar *lastname = Ustrrchr(buffer, '/') + 1;
197 int namelen = Ustrlen(name);
200 dd = opendir(CS buffer);
202 while ((ent = readdir(dd)) != NULL)
204 if (Ustrncmp(ent->d_name, name, namelen) == 0)
207 Ustrcpy(lastname, ent->d_name);
208 if (Ustat(buffer, &statbuf) >= 0 && statbuf.st_uid != exim_uid)
210 DEBUG(D_hints_lookup) debug_printf("ensuring %s is owned by exim\n", buffer);
211 if (Uchown(buffer, exim_uid, exim_gid))
212 DEBUG(D_hints_lookup) debug_printf("failed setting %s to owned by exim\n", buffer);
220 /* If the open has failed, return NULL, leaving errno set. If lof is TRUE,
221 log the event - also for debugging - but not if the file just doesn't exist. */
223 if (dbblock->dbptr == NULL)
225 if (save_errno != ENOENT)
228 log_write(0, LOG_MAIN, "%s", string_open_failed(save_errno, "DB file %s",
231 DEBUG(D_hints_lookup)
232 debug_printf("%s", CS string_open_failed(save_errno, "DB file %s\n",
235 (void)close(dbblock->lockfd);
240 DEBUG(D_hints_lookup)
241 debug_printf("opened hints database %s: flags=%s\n", buffer,
242 (flags == O_RDONLY)? "O_RDONLY" : (flags == O_RDWR)? "O_RDWR" :
243 (flags == (O_RDWR|O_CREAT))? "O_RDWR|O_CREAT" : "??");
245 /* Pass back the block containing the opened database handle and the open fd
254 /*************************************************
255 * Unlock and close a database file *
256 *************************************************/
258 /* Closing a file automatically unlocks it, so after closing the database, just
261 Argument: a pointer to an open database block
266 dbfn_close(open_db *dbblock)
268 EXIM_DBCLOSE(dbblock->dbptr);
269 (void)close(dbblock->lockfd);
275 /*************************************************
276 * Read from database file *
277 *************************************************/
279 /* Passing back the pointer unchanged is useless, because there is
280 no guarantee of alignment. Since all the records used by Exim need
281 to be properly aligned to pick out the timestamps, etc., we might as
282 well do the copying centrally here.
284 Most calls don't need the length, so there is a macro called dbfn_read which
285 has two arguments; it calls this function adding NULL as the third.
288 dbblock a pointer to an open database block
289 key the key of the record to be read
290 length a pointer to an int into which to return the length, if not NULL
292 Returns: a pointer to the retrieved record, or
293 NULL if the record is not found
297 dbfn_read_with_length(open_db *dbblock, uschar *key, int *length)
300 EXIM_DATUM key_datum, result_datum;
302 DEBUG(D_hints_lookup) debug_printf("dbfn_read: key=%s\n", key);
304 EXIM_DATUM_INIT(key_datum); /* Some DBM libraries require the datum */
305 EXIM_DATUM_INIT(result_datum); /* to be cleared before use. */
306 EXIM_DATUM_DATA(key_datum) = CS key;
307 EXIM_DATUM_SIZE(key_datum) = Ustrlen(key) + 1;
309 if (!EXIM_DBGET(dbblock->dbptr, key_datum, result_datum)) return NULL;
311 yield = store_get(EXIM_DATUM_SIZE(result_datum));
312 memcpy(yield, EXIM_DATUM_DATA(result_datum), EXIM_DATUM_SIZE(result_datum));
313 if (length != NULL) *length = EXIM_DATUM_SIZE(result_datum);
315 EXIM_DATUM_FREE(result_datum); /* Some DBM libs require freeing */
321 /*************************************************
322 * Write to database file *
323 *************************************************/
327 dbblock a pointer to an open database block
328 key the key of the record to be written
329 ptr a pointer to the record to be written
330 length the length of the record to be written
332 Returns: the yield of the underlying dbm or db "write" function. If this
333 is dbm, the value is zero for OK.
337 dbfn_write(open_db *dbblock, uschar *key, void *ptr, int length)
339 EXIM_DATUM key_datum, value_datum;
340 dbdata_generic *gptr = (dbdata_generic *)ptr;
341 gptr->time_stamp = time(NULL);
343 DEBUG(D_hints_lookup) debug_printf("dbfn_write: key=%s\n", key);
345 EXIM_DATUM_INIT(key_datum); /* Some DBM libraries require the datum */
346 EXIM_DATUM_INIT(value_datum); /* to be cleared before use. */
347 EXIM_DATUM_DATA(key_datum) = CS key;
348 EXIM_DATUM_SIZE(key_datum) = Ustrlen(key) + 1;
349 EXIM_DATUM_DATA(value_datum) = CS ptr;
350 EXIM_DATUM_SIZE(value_datum) = length;
351 return EXIM_DBPUT(dbblock->dbptr, key_datum, value_datum);
356 /*************************************************
357 * Delete record from database file *
358 *************************************************/
362 dbblock a pointer to an open database block
363 key the key of the record to be deleted
365 Returns: the yield of the underlying dbm or db "delete" function.
369 dbfn_delete(open_db *dbblock, uschar *key)
371 EXIM_DATUM key_datum;
372 EXIM_DATUM_INIT(key_datum); /* Some DBM libraries require clearing */
373 EXIM_DATUM_DATA(key_datum) = CS key;
374 EXIM_DATUM_SIZE(key_datum) = Ustrlen(key) + 1;
375 return EXIM_DBDEL(dbblock->dbptr, key_datum);
380 /*************************************************
381 * Scan the keys of a database file *
382 *************************************************/
386 dbblock a pointer to an open database block
387 start TRUE if starting a new scan
388 FALSE if continuing with the current scan
389 cursor a pointer to a pointer to a cursor anchor, for those dbm libraries
390 that use the notion of a cursor
392 Returns: the next record from the file, or
393 NULL if there are no more
397 dbfn_scan(open_db *dbblock, BOOL start, EXIM_CURSOR **cursor)
399 EXIM_DATUM key_datum, value_datum;
401 value_datum = value_datum; /* dummy; not all db libraries use this */
403 /* Some dbm require an initialization */
405 if (start) EXIM_DBCREATE_CURSOR(dbblock->dbptr, cursor);
407 EXIM_DATUM_INIT(key_datum); /* Some DBM libraries require the datum */
408 EXIM_DATUM_INIT(value_datum); /* to be cleared before use. */
410 yield = (EXIM_DBSCAN(dbblock->dbptr, key_datum, value_datum, start, *cursor))?
411 US EXIM_DATUM_DATA(key_datum) : NULL;
413 /* Some dbm require a termination */
415 if (!yield) EXIM_DBDELETE_CURSOR(*cursor);
421 /*************************************************
422 **************************************************
423 * Stand-alone test program *
424 **************************************************
425 *************************************************/
430 main(int argc, char **cargv)
433 int max_db = sizeof(dbblock)/sizeof(open_db);
437 dbdata_wait *dbwait = NULL;
438 uschar **argv = USS cargv;
440 uschar structbuffer[1024];
444 printf("Usage: test_dbfn directory\n");
445 printf("The subdirectory called \"db\" in the given directory is used for\n");
446 printf("the files used in this test program.\n");
452 spool_directory = argv[1];
453 debug_selector = D_all - D_memory;
455 big_buffer = malloc(big_buffer_size);
457 for (i = 0; i < max_db; i++) dbblock[i].dbptr = NULL;
459 printf("\nExim's db functions tester: interface type is %s\n", EXIM_DBTYPE);
460 printf("DBM library: ");
462 #ifdef DB_VERSION_STRING
463 printf("Berkeley DB: %s\n", DB_VERSION_STRING);
464 #elif defined(BTREEVERSION) && defined(HASHVERSION)
466 printf("probably Berkeley DB version 1.8x (native mode)\n");
468 printf("probably Berkeley DB version 1.8x (compatibility mode)\n");
470 #elif defined(_DBM_RDONLY) || defined(dbm_dirfno)
471 printf("probably ndbm\n");
472 #elif defined(USE_TDB)
473 printf("using tdb\n");
476 printf("probably GDBM (native mode)\n");
478 printf("probably GDBM (compatibility mode)\n");
482 /* Test the functions */
484 printf("\nTest the functions\n> ");
486 while (Ufgets(buffer, 256, stdin) != NULL)
488 int len = Ustrlen(buffer);
492 uschar *cmd = buffer;
493 while (len > 0 && isspace((uschar)buffer[len-1])) len--;
496 if (isdigit((uschar)*cmd))
499 while (isdigit((uschar)*cmd)) cmd++;
500 while (isspace((uschar)*cmd)) cmd++;
503 if (Ustrncmp(cmd, "open", 4) == 0)
508 while (isspace((uschar)*s)) s++;
510 for (i = 0; i < max_db; i++)
511 if (dbblock[i].dbptr == NULL) break;
515 printf("Too many open databases\n> ");
520 odb = dbfn_open(s, O_RDWR, dbblock + i, TRUE);
526 printf("opened %d\n", current);
528 /* Other error cases will have written messages */
529 else if (errno == ENOENT)
531 printf("open failed: %s%s\n", strerror(errno),
533 " (or other Berkeley DB error)"
541 else if (Ustrncmp(cmd, "write", 5) == 0)
544 uschar *key = cmd + 5;
549 printf("No current database\n");
553 while (isspace((uschar)*key)) key++;
555 while (*data != 0 && !isspace((uschar)*data)) data++;
557 while (isspace((uschar)*data)) data++;
559 dbwait = (dbdata_wait *)(&structbuffer);
560 Ustrcpy(dbwait->text, data);
564 rc = dbfn_write(dbblock + current, key, dbwait,
565 Ustrlen(data) + sizeof(dbdata_wait));
567 if (rc != 0) printf("Failed: %s\n", strerror(errno));
570 else if (Ustrncmp(cmd, "read", 4) == 0)
572 uschar *key = cmd + 4;
575 printf("No current database\n");
578 while (isspace((uschar)*key)) key++;
581 dbwait = (dbdata_wait *)dbfn_read_with_length(dbblock+ current, key, NULL);
583 printf("%s\n", (dbwait == NULL)? "<not found>" : CS dbwait->text);
586 else if (Ustrncmp(cmd, "delete", 6) == 0)
588 uschar *key = cmd + 6;
591 printf("No current database\n");
594 while (isspace((uschar)*key)) key++;
595 dbfn_delete(dbblock + current, key);
598 else if (Ustrncmp(cmd, "scan", 4) == 0)
601 BOOL startflag = TRUE;
603 uschar keybuffer[256];
606 printf("No current database\n");
610 while ((key = dbfn_scan(dbblock + current, startflag, &cursor)) != NULL)
613 Ustrcpy(keybuffer, key);
614 dbwait = (dbdata_wait *)dbfn_read_with_length(dbblock + current,
616 printf("%s: %s\n", keybuffer, dbwait->text);
619 printf("End of scan\n");
622 else if (Ustrncmp(cmd, "close", 5) == 0)
625 while (isspace((uschar)*s)) s++;
627 if (i >= max_db || dbblock[i].dbptr == NULL) printf("Not open\n"); else
630 dbfn_close(dbblock + i);
632 dbblock[i].dbptr = NULL;
633 if (i == current) current = -1;
637 else if (Ustrncmp(cmd, "file", 4) == 0)
640 while (isspace((uschar)*s)) s++;
642 if (i >= max_db || dbblock[i].dbptr == NULL) printf("Not open\n");
646 else if (Ustrncmp(cmd, "time", 4) == 0)
648 showtime = ~showtime;
649 printf("Timing %s\n", showtime? "on" : "off");
652 else if (Ustrcmp(cmd, "q") == 0 || Ustrncmp(cmd, "quit", 4) == 0) break;
654 else if (Ustrncmp(cmd, "help", 4) == 0)
656 printf("close [<number>] close file [<number>]\n");
657 printf("delete <key> remove record from current file\n");
658 printf("file <number> make file <number> current\n");
659 printf("open <name> open db file\n");
660 printf("q[uit] exit program\n");
661 printf("read <key> read record from current file\n");
662 printf("scan scan current file\n");
663 printf("time time display on/off\n");
664 printf("write <key> <rest-of-line> write record to current file\n");
667 else printf("Eh?\n");
669 if (showtime && stop >= start)
670 printf("start=%d stop=%d difference=%d\n", (int)start, (int)stop,
671 (int)(stop - start));
676 for (i = 0; i < max_db; i++)
678 if (dbblock[i].dbptr != NULL)
680 printf("\nClosing %d", i);
681 dbfn_close(dbblock + i);