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 (void)Uchown(buffer, exim_uid, exim_gid);
219 /* If the open has failed, return NULL, leaving errno set. If lof is TRUE,
220 log the event - also for debugging - but not if the file just doesn't exist. */
222 if (dbblock->dbptr == NULL)
224 if (save_errno != ENOENT)
227 log_write(0, LOG_MAIN, "%s", string_open_failed(save_errno, "DB file %s",
230 DEBUG(D_hints_lookup)
231 debug_printf("%s", CS string_open_failed(save_errno, "DB file %s\n",
234 (void)close(dbblock->lockfd);
239 DEBUG(D_hints_lookup)
240 debug_printf("opened hints database %s: flags=%s\n", buffer,
241 (flags == O_RDONLY)? "O_RDONLY" : (flags == O_RDWR)? "O_RDWR" :
242 (flags == (O_RDWR|O_CREAT))? "O_RDWR|O_CREAT" : "??");
244 /* Pass back the block containing the opened database handle and the open fd
253 /*************************************************
254 * Unlock and close a database file *
255 *************************************************/
257 /* Closing a file automatically unlocks it, so after closing the database, just
260 Argument: a pointer to an open database block
265 dbfn_close(open_db *dbblock)
267 EXIM_DBCLOSE(dbblock->dbptr);
268 (void)close(dbblock->lockfd);
274 /*************************************************
275 * Read from database file *
276 *************************************************/
278 /* Passing back the pointer unchanged is useless, because there is
279 no guarantee of alignment. Since all the records used by Exim need
280 to be properly aligned to pick out the timestamps, etc., we might as
281 well do the copying centrally here.
283 Most calls don't need the length, so there is a macro called dbfn_read which
284 has two arguments; it calls this function adding NULL as the third.
287 dbblock a pointer to an open database block
288 key the key of the record to be read
289 length a pointer to an int into which to return the length, if not NULL
291 Returns: a pointer to the retrieved record, or
292 NULL if the record is not found
296 dbfn_read_with_length(open_db *dbblock, uschar *key, int *length)
299 EXIM_DATUM key_datum, result_datum;
301 DEBUG(D_hints_lookup) debug_printf("dbfn_read: key=%s\n", key);
303 EXIM_DATUM_INIT(key_datum); /* Some DBM libraries require the datum */
304 EXIM_DATUM_INIT(result_datum); /* to be cleared before use. */
305 EXIM_DATUM_DATA(key_datum) = CS key;
306 EXIM_DATUM_SIZE(key_datum) = Ustrlen(key) + 1;
308 if (!EXIM_DBGET(dbblock->dbptr, key_datum, result_datum)) return NULL;
310 yield = store_get(EXIM_DATUM_SIZE(result_datum));
311 memcpy(yield, EXIM_DATUM_DATA(result_datum), EXIM_DATUM_SIZE(result_datum));
312 if (length != NULL) *length = EXIM_DATUM_SIZE(result_datum);
314 EXIM_DATUM_FREE(result_datum); /* Some DBM libs require freeing */
320 /*************************************************
321 * Write to database file *
322 *************************************************/
326 dbblock a pointer to an open database block
327 key the key of the record to be written
328 ptr a pointer to the record to be written
329 length the length of the record to be written
331 Returns: the yield of the underlying dbm or db "write" function. If this
332 is dbm, the value is zero for OK.
336 dbfn_write(open_db *dbblock, uschar *key, void *ptr, int length)
338 EXIM_DATUM key_datum, value_datum;
339 dbdata_generic *gptr = (dbdata_generic *)ptr;
340 gptr->time_stamp = time(NULL);
342 DEBUG(D_hints_lookup) debug_printf("dbfn_write: key=%s\n", key);
344 EXIM_DATUM_INIT(key_datum); /* Some DBM libraries require the datum */
345 EXIM_DATUM_INIT(value_datum); /* to be cleared before use. */
346 EXIM_DATUM_DATA(key_datum) = CS key;
347 EXIM_DATUM_SIZE(key_datum) = Ustrlen(key) + 1;
348 EXIM_DATUM_DATA(value_datum) = CS ptr;
349 EXIM_DATUM_SIZE(value_datum) = length;
350 return EXIM_DBPUT(dbblock->dbptr, key_datum, value_datum);
355 /*************************************************
356 * Delete record from database file *
357 *************************************************/
361 dbblock a pointer to an open database block
362 key the key of the record to be deleted
364 Returns: the yield of the underlying dbm or db "delete" function.
368 dbfn_delete(open_db *dbblock, uschar *key)
370 EXIM_DATUM key_datum;
371 EXIM_DATUM_INIT(key_datum); /* Some DBM libraries require clearing */
372 EXIM_DATUM_DATA(key_datum) = CS key;
373 EXIM_DATUM_SIZE(key_datum) = Ustrlen(key) + 1;
374 return EXIM_DBDEL(dbblock->dbptr, key_datum);
379 /*************************************************
380 * Scan the keys of a database file *
381 *************************************************/
385 dbblock a pointer to an open database block
386 start TRUE if starting a new scan
387 FALSE if continuing with the current scan
388 cursor a pointer to a pointer to a cursor anchor, for those dbm libraries
389 that use the notion of a cursor
391 Returns: the next record from the file, or
392 NULL if there are no more
396 dbfn_scan(open_db *dbblock, BOOL start, EXIM_CURSOR **cursor)
398 EXIM_DATUM key_datum, value_datum;
400 value_datum = value_datum; /* dummy; not all db libraries use this */
402 /* Some dbm require an initialization */
404 if (start) EXIM_DBCREATE_CURSOR(dbblock->dbptr, cursor);
406 EXIM_DATUM_INIT(key_datum); /* Some DBM libraries require the datum */
407 EXIM_DATUM_INIT(value_datum); /* to be cleared before use. */
409 yield = (EXIM_DBSCAN(dbblock->dbptr, key_datum, value_datum, start, *cursor))?
410 US EXIM_DATUM_DATA(key_datum) : NULL;
412 /* Some dbm require a termination */
414 if (!yield) EXIM_DBDELETE_CURSOR(*cursor);
420 /*************************************************
421 **************************************************
422 * Stand-alone test program *
423 **************************************************
424 *************************************************/
429 main(int argc, char **cargv)
432 int max_db = sizeof(dbblock)/sizeof(open_db);
436 dbdata_wait *dbwait = NULL;
437 uschar **argv = USS cargv;
439 uschar structbuffer[1024];
443 printf("Usage: test_dbfn directory\n");
444 printf("The subdirectory called \"db\" in the given directory is used for\n");
445 printf("the files used in this test program.\n");
451 spool_directory = argv[1];
452 debug_selector = D_all - D_memory;
454 big_buffer = malloc(big_buffer_size);
456 for (i = 0; i < max_db; i++) dbblock[i].dbptr = NULL;
458 printf("\nExim's db functions tester: interface type is %s\n", EXIM_DBTYPE);
459 printf("DBM library: ");
461 #ifdef DB_VERSION_STRING
462 printf("Berkeley DB: %s\n", DB_VERSION_STRING);
463 #elif defined(BTREEVERSION) && defined(HASHVERSION)
465 printf("probably Berkeley DB version 1.8x (native mode)\n");
467 printf("probably Berkeley DB version 1.8x (compatibility mode)\n");
469 #elif defined(_DBM_RDONLY) || defined(dbm_dirfno)
470 printf("probably ndbm\n");
471 #elif defined(USE_TDB)
472 printf("using tdb\n");
475 printf("probably GDBM (native mode)\n");
477 printf("probably GDBM (compatibility mode)\n");
481 /* Test the functions */
483 printf("\nTest the functions\n> ");
485 while (Ufgets(buffer, 256, stdin) != NULL)
487 int len = Ustrlen(buffer);
491 uschar *cmd = buffer;
492 while (len > 0 && isspace((uschar)buffer[len-1])) len--;
495 if (isdigit((uschar)*cmd))
498 while (isdigit((uschar)*cmd)) cmd++;
499 while (isspace((uschar)*cmd)) cmd++;
502 if (Ustrncmp(cmd, "open", 4) == 0)
507 while (isspace((uschar)*s)) s++;
509 for (i = 0; i < max_db; i++)
510 if (dbblock[i].dbptr == NULL) break;
514 printf("Too many open databases\n> ");
519 odb = dbfn_open(s, O_RDWR, dbblock + i, TRUE);
525 printf("opened %d\n", current);
527 /* Other error cases will have written messages */
528 else if (errno == ENOENT)
530 printf("open failed: %s%s\n", strerror(errno),
532 " (or other Berkeley DB error)"
540 else if (Ustrncmp(cmd, "write", 5) == 0)
543 uschar *key = cmd + 5;
548 printf("No current database\n");
552 while (isspace((uschar)*key)) key++;
554 while (*data != 0 && !isspace((uschar)*data)) data++;
556 while (isspace((uschar)*data)) data++;
558 dbwait = (dbdata_wait *)(&structbuffer);
559 Ustrcpy(dbwait->text, data);
563 rc = dbfn_write(dbblock + current, key, dbwait,
564 Ustrlen(data) + sizeof(dbdata_wait));
566 if (rc != 0) printf("Failed: %s\n", strerror(errno));
569 else if (Ustrncmp(cmd, "read", 4) == 0)
571 uschar *key = cmd + 4;
574 printf("No current database\n");
577 while (isspace((uschar)*key)) key++;
580 dbwait = (dbdata_wait *)dbfn_read_with_length(dbblock+ current, key, NULL);
582 printf("%s\n", (dbwait == NULL)? "<not found>" : CS dbwait->text);
585 else if (Ustrncmp(cmd, "delete", 6) == 0)
587 uschar *key = cmd + 6;
590 printf("No current database\n");
593 while (isspace((uschar)*key)) key++;
594 dbfn_delete(dbblock + current, key);
597 else if (Ustrncmp(cmd, "scan", 4) == 0)
600 BOOL startflag = TRUE;
602 uschar keybuffer[256];
605 printf("No current database\n");
609 while ((key = dbfn_scan(dbblock + current, startflag, &cursor)) != NULL)
612 Ustrcpy(keybuffer, key);
613 dbwait = (dbdata_wait *)dbfn_read_with_length(dbblock + current,
615 printf("%s: %s\n", keybuffer, dbwait->text);
618 printf("End of scan\n");
621 else if (Ustrncmp(cmd, "close", 5) == 0)
624 while (isspace((uschar)*s)) s++;
626 if (i >= max_db || dbblock[i].dbptr == NULL) printf("Not open\n"); else
629 dbfn_close(dbblock + i);
631 dbblock[i].dbptr = NULL;
632 if (i == current) current = -1;
636 else if (Ustrncmp(cmd, "file", 4) == 0)
639 while (isspace((uschar)*s)) s++;
641 if (i >= max_db || dbblock[i].dbptr == NULL) printf("Not open\n");
645 else if (Ustrncmp(cmd, "time", 4) == 0)
647 showtime = ~showtime;
648 printf("Timing %s\n", showtime? "on" : "off");
651 else if (Ustrcmp(cmd, "q") == 0 || Ustrncmp(cmd, "quit", 4) == 0) break;
653 else if (Ustrncmp(cmd, "help", 4) == 0)
655 printf("close [<number>] close file [<number>]\n");
656 printf("delete <key> remove record from current file\n");
657 printf("file <number> make file <number> current\n");
658 printf("open <name> open db file\n");
659 printf("q[uit] exit program\n");
660 printf("read <key> read record from current file\n");
661 printf("scan scan current file\n");
662 printf("time time display on/off\n");
663 printf("write <key> <rest-of-line> write record to current file\n");
666 else printf("Eh?\n");
668 if (showtime && stop >= start)
669 printf("start=%d stop=%d difference=%d\n", (int)start, (int)stop,
670 (int)(stop - start));
675 for (i = 0; i < max_db; i++)
677 if (dbblock[i].dbptr != NULL)
679 printf("\nClosing %d", i);
680 dbfn_close(dbblock + i);