1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
5 /* Copyright (c) University of Cambridge 1995 - 2015 */
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;
94 uschar dirname[256], filename[256];
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 snprintf(CS dirname, sizeof(dirname), "%s/db", spool_directory);
110 snprintf(CS filename, sizeof(filename), "%s/%s.lockfile", dirname, name);
112 if ((dbblock->lockfd = Uopen(filename, O_RDWR, EXIMDB_LOCKFILE_MODE)) < 0)
115 (void)directory_make(spool_directory, US"db", EXIMDB_DIRECTORY_MODE, TRUE);
116 dbblock->lockfd = Uopen(filename, O_RDWR|O_CREAT, EXIMDB_LOCKFILE_MODE);
119 if (dbblock->lockfd < 0)
121 log_write(0, LOG_MAIN, "%s",
122 string_open_failed(errno, "database lock file %s", filename));
123 errno = 0; /* Indicates locking failure */
127 /* Now we must get a lock on the opened lock file; do this with a blocking
128 lock that times out. */
130 lock_data.l_type = read_only? F_RDLCK : F_WRLCK;
131 lock_data.l_whence = lock_data.l_start = lock_data.l_len = 0;
133 DEBUG(D_hints_lookup|D_retry|D_route|D_deliver)
134 debug_printf("locking %s\n", filename);
136 sigalrm_seen = FALSE;
137 alarm(EXIMDB_LOCK_TIMEOUT);
138 rc = fcntl(dbblock->lockfd, F_SETLKW, &lock_data);
141 if (sigalrm_seen) errno = ETIMEDOUT;
144 log_write(0, LOG_MAIN|LOG_PANIC, "Failed to get %s lock for %s: %s",
145 read_only ? "read" : "write", filename,
146 errno == ETIMEDOUT ? "timed out" : strerror(errno));
147 (void)close(dbblock->lockfd);
148 errno = 0; /* Indicates locking failure */
152 DEBUG(D_hints_lookup) debug_printf("locked %s\n", filename);
154 /* At this point we have an opened and locked separate lock file, that is,
155 exclusive access to the database, so we can go ahead and open it. If we are
156 expected to create it, don't do so at first, again so that we can detect
157 whether we need to change its ownership (see comments about the lock file
158 above.) There have been regular reports of crashes while opening hints
159 databases - often this is caused by non-matching db.h and the library. To make
160 it easy to pin this down, there are now debug statements on either side of the
163 snprintf(CS filename, sizeof(filename), "%s/%s", dirname, name);
164 EXIM_DBOPEN(filename, dirname, flags, EXIMDB_MODE, &(dbblock->dbptr));
166 if (!dbblock->dbptr && errno == ENOENT && flags == O_RDWR)
168 DEBUG(D_hints_lookup)
169 debug_printf("%s appears not to exist: trying to create\n", filename);
171 EXIM_DBOPEN(filename, dirname, flags|O_CREAT, EXIMDB_MODE, &(dbblock->dbptr));
176 /* If we are running as root and this is the first access to the database, its
177 files will be owned by root. We want them to be owned by exim. We detect this
178 situation by noting above when we had to create the lock file or the database
179 itself. Because the different dbm libraries use different extensions for their
180 files, I don't know of any easier way of arranging this than scanning the
181 directory for files with the appropriate base name. At least this deals with
182 the lock file at the same time. Also, the directory will typically have only
183 half a dozen files, so the scan will be quick.
185 This code is placed here, before the test for successful opening, because there
186 was a case when a file was created, but the DBM library still returned NULL
187 because of some problem. It also sorts out the lock file if that was created
188 but creation of the database file failed. */
190 if (created && geteuid() == root_uid)
194 uschar *lastname = Ustrrchr(filename, '/') + 1;
195 int namelen = Ustrlen(name);
198 dd = opendir(CS filename);
200 while ((ent = readdir(dd)))
201 if (Ustrncmp(ent->d_name, name, namelen) == 0)
204 Ustrcpy(lastname, ent->d_name);
205 if (Ustat(filename, &statbuf) >= 0 && statbuf.st_uid != exim_uid)
207 DEBUG(D_hints_lookup) debug_printf("ensuring %s is owned by exim\n", filename);
208 if (Uchown(filename, exim_uid, exim_gid))
209 DEBUG(D_hints_lookup) debug_printf("failed setting %s to owned by exim\n", filename);
216 /* If the open has failed, return NULL, leaving errno set. If lof is TRUE,
217 log the event - also for debugging - but debug only if the file just doesn't
222 if (lof && save_errno != ENOENT)
223 log_write(0, LOG_MAIN, "%s", string_open_failed(save_errno, "DB file %s",
226 DEBUG(D_hints_lookup)
227 debug_printf("%s\n", CS string_open_failed(save_errno, "DB file %s",
229 (void)close(dbblock->lockfd);
234 DEBUG(D_hints_lookup)
235 debug_printf("opened hints database %s: flags=%s\n", filename,
236 flags == O_RDONLY ? "O_RDONLY"
237 : flags == O_RDWR ? "O_RDWR"
238 : flags == (O_RDWR|O_CREAT) ? "O_RDWR|O_CREAT"
241 /* Pass back the block containing the opened database handle and the open fd
250 /*************************************************
251 * Unlock and close a database file *
252 *************************************************/
254 /* Closing a file automatically unlocks it, so after closing the database, just
257 Argument: a pointer to an open database block
262 dbfn_close(open_db *dbblock)
264 EXIM_DBCLOSE(dbblock->dbptr);
265 (void)close(dbblock->lockfd);
266 DEBUG(D_hints_lookup) debug_printf("closed hints database and lockfile\n");
272 /*************************************************
273 * Read from database file *
274 *************************************************/
276 /* Passing back the pointer unchanged is useless, because there is
277 no guarantee of alignment. Since all the records used by Exim need
278 to be properly aligned to pick out the timestamps, etc., we might as
279 well do the copying centrally here.
281 Most calls don't need the length, so there is a macro called dbfn_read which
282 has two arguments; it calls this function adding NULL as the third.
285 dbblock a pointer to an open database block
286 key the key of the record to be read
287 length a pointer to an int into which to return the length, if not NULL
289 Returns: a pointer to the retrieved record, or
290 NULL if the record is not found
294 dbfn_read_with_length(open_db *dbblock, const uschar *key, int *length)
297 EXIM_DATUM key_datum, result_datum;
298 int klen = Ustrlen(key) + 1;
299 uschar * key_copy = store_get(klen);
301 memcpy(key_copy, key, klen);
303 DEBUG(D_hints_lookup) debug_printf("dbfn_read: key=%s\n", key);
305 EXIM_DATUM_INIT(key_datum); /* Some DBM libraries require the datum */
306 EXIM_DATUM_INIT(result_datum); /* to be cleared before use. */
307 EXIM_DATUM_DATA(key_datum) = CS key_copy;
308 EXIM_DATUM_SIZE(key_datum) = klen;
310 if (!EXIM_DBGET(dbblock->dbptr, key_datum, result_datum)) return NULL;
312 yield = store_get(EXIM_DATUM_SIZE(result_datum));
313 memcpy(yield, EXIM_DATUM_DATA(result_datum), EXIM_DATUM_SIZE(result_datum));
314 if (length != NULL) *length = EXIM_DATUM_SIZE(result_datum);
316 EXIM_DATUM_FREE(result_datum); /* Some DBM libs require freeing */
322 /*************************************************
323 * Write to database file *
324 *************************************************/
328 dbblock a pointer to an open database block
329 key the key of the record to be written
330 ptr a pointer to the record to be written
331 length the length of the record to be written
333 Returns: the yield of the underlying dbm or db "write" function. If this
334 is dbm, the value is zero for OK.
338 dbfn_write(open_db *dbblock, const uschar *key, void *ptr, int length)
340 EXIM_DATUM key_datum, value_datum;
341 dbdata_generic *gptr = (dbdata_generic *)ptr;
342 int klen = Ustrlen(key) + 1;
343 uschar * key_copy = store_get(klen);
345 memcpy(key_copy, key, klen);
346 gptr->time_stamp = time(NULL);
348 DEBUG(D_hints_lookup) debug_printf("dbfn_write: key=%s\n", key);
350 EXIM_DATUM_INIT(key_datum); /* Some DBM libraries require the datum */
351 EXIM_DATUM_INIT(value_datum); /* to be cleared before use. */
352 EXIM_DATUM_DATA(key_datum) = CS key_copy;
353 EXIM_DATUM_SIZE(key_datum) = klen;
354 EXIM_DATUM_DATA(value_datum) = CS ptr;
355 EXIM_DATUM_SIZE(value_datum) = length;
356 return EXIM_DBPUT(dbblock->dbptr, key_datum, value_datum);
361 /*************************************************
362 * Delete record from database file *
363 *************************************************/
367 dbblock a pointer to an open database block
368 key the key of the record to be deleted
370 Returns: the yield of the underlying dbm or db "delete" function.
374 dbfn_delete(open_db *dbblock, const uschar *key)
376 int klen = Ustrlen(key) + 1;
377 uschar * key_copy = store_get(klen);
379 memcpy(key_copy, key, klen);
380 EXIM_DATUM key_datum;
381 EXIM_DATUM_INIT(key_datum); /* Some DBM libraries require clearing */
382 EXIM_DATUM_DATA(key_datum) = CS key_copy;
383 EXIM_DATUM_SIZE(key_datum) = klen;
384 return EXIM_DBDEL(dbblock->dbptr, key_datum);
389 /*************************************************
390 * Scan the keys of a database file *
391 *************************************************/
395 dbblock a pointer to an open database block
396 start TRUE if starting a new scan
397 FALSE if continuing with the current scan
398 cursor a pointer to a pointer to a cursor anchor, for those dbm libraries
399 that use the notion of a cursor
401 Returns: the next record from the file, or
402 NULL if there are no more
406 dbfn_scan(open_db *dbblock, BOOL start, EXIM_CURSOR **cursor)
408 EXIM_DATUM key_datum, value_datum;
410 value_datum = value_datum; /* dummy; not all db libraries use this */
412 /* Some dbm require an initialization */
414 if (start) EXIM_DBCREATE_CURSOR(dbblock->dbptr, cursor);
416 EXIM_DATUM_INIT(key_datum); /* Some DBM libraries require the datum */
417 EXIM_DATUM_INIT(value_datum); /* to be cleared before use. */
419 yield = (EXIM_DBSCAN(dbblock->dbptr, key_datum, value_datum, start, *cursor))?
420 US EXIM_DATUM_DATA(key_datum) : NULL;
422 /* Some dbm require a termination */
424 if (!yield) EXIM_DBDELETE_CURSOR(*cursor);
430 /*************************************************
431 **************************************************
432 * Stand-alone test program *
433 **************************************************
434 *************************************************/
439 main(int argc, char **cargv)
442 int max_db = sizeof(dbblock)/sizeof(open_db);
446 dbdata_wait *dbwait = NULL;
447 uschar **argv = USS cargv;
449 uschar structbuffer[1024];
453 printf("Usage: test_dbfn directory\n");
454 printf("The subdirectory called \"db\" in the given directory is used for\n");
455 printf("the files used in this test program.\n");
461 spool_directory = argv[1];
462 debug_selector = D_all - D_memory;
464 big_buffer = malloc(big_buffer_size);
466 for (i = 0; i < max_db; i++) dbblock[i].dbptr = NULL;
468 printf("\nExim's db functions tester: interface type is %s\n", EXIM_DBTYPE);
469 printf("DBM library: ");
471 #ifdef DB_VERSION_STRING
472 printf("Berkeley DB: %s\n", DB_VERSION_STRING);
473 #elif defined(BTREEVERSION) && defined(HASHVERSION)
475 printf("probably Berkeley DB version 1.8x (native mode)\n");
477 printf("probably Berkeley DB version 1.8x (compatibility mode)\n");
479 #elif defined(_DBM_RDONLY) || defined(dbm_dirfno)
480 printf("probably ndbm\n");
481 #elif defined(USE_TDB)
482 printf("using tdb\n");
485 printf("probably GDBM (native mode)\n");
487 printf("probably GDBM (compatibility mode)\n");
491 /* Test the functions */
493 printf("\nTest the functions\n> ");
495 while (Ufgets(buffer, 256, stdin) != NULL)
497 int len = Ustrlen(buffer);
501 uschar *cmd = buffer;
502 while (len > 0 && isspace((uschar)buffer[len-1])) len--;
505 if (isdigit((uschar)*cmd))
508 while (isdigit((uschar)*cmd)) cmd++;
509 while (isspace((uschar)*cmd)) cmd++;
512 if (Ustrncmp(cmd, "open", 4) == 0)
517 while (isspace((uschar)*s)) s++;
519 for (i = 0; i < max_db; i++)
520 if (dbblock[i].dbptr == NULL) break;
524 printf("Too many open databases\n> ");
529 odb = dbfn_open(s, O_RDWR, dbblock + i, TRUE);
535 printf("opened %d\n", current);
537 /* Other error cases will have written messages */
538 else if (errno == ENOENT)
540 printf("open failed: %s%s\n", strerror(errno),
542 " (or other Berkeley DB error)"
550 else if (Ustrncmp(cmd, "write", 5) == 0)
553 uschar *key = cmd + 5;
558 printf("No current database\n");
562 while (isspace((uschar)*key)) key++;
564 while (*data != 0 && !isspace((uschar)*data)) data++;
566 while (isspace((uschar)*data)) data++;
568 dbwait = (dbdata_wait *)(&structbuffer);
569 Ustrcpy(dbwait->text, data);
573 rc = dbfn_write(dbblock + current, key, dbwait,
574 Ustrlen(data) + sizeof(dbdata_wait));
576 if (rc != 0) printf("Failed: %s\n", strerror(errno));
579 else if (Ustrncmp(cmd, "read", 4) == 0)
581 uschar *key = cmd + 4;
584 printf("No current database\n");
587 while (isspace((uschar)*key)) key++;
590 dbwait = (dbdata_wait *)dbfn_read_with_length(dbblock+ current, key, NULL);
592 printf("%s\n", (dbwait == NULL)? "<not found>" : CS dbwait->text);
595 else if (Ustrncmp(cmd, "delete", 6) == 0)
597 uschar *key = cmd + 6;
600 printf("No current database\n");
603 while (isspace((uschar)*key)) key++;
604 dbfn_delete(dbblock + current, key);
607 else if (Ustrncmp(cmd, "scan", 4) == 0)
610 BOOL startflag = TRUE;
612 uschar keybuffer[256];
615 printf("No current database\n");
619 while ((key = dbfn_scan(dbblock + current, startflag, &cursor)) != NULL)
622 Ustrcpy(keybuffer, key);
623 dbwait = (dbdata_wait *)dbfn_read_with_length(dbblock + current,
625 printf("%s: %s\n", keybuffer, dbwait->text);
628 printf("End of scan\n");
631 else if (Ustrncmp(cmd, "close", 5) == 0)
634 while (isspace((uschar)*s)) s++;
636 if (i >= max_db || dbblock[i].dbptr == NULL) printf("Not open\n"); else
639 dbfn_close(dbblock + i);
641 dbblock[i].dbptr = NULL;
642 if (i == current) current = -1;
646 else if (Ustrncmp(cmd, "file", 4) == 0)
649 while (isspace((uschar)*s)) s++;
651 if (i >= max_db || dbblock[i].dbptr == NULL) printf("Not open\n");
655 else if (Ustrncmp(cmd, "time", 4) == 0)
657 showtime = ~showtime;
658 printf("Timing %s\n", showtime? "on" : "off");
661 else if (Ustrcmp(cmd, "q") == 0 || Ustrncmp(cmd, "quit", 4) == 0) break;
663 else if (Ustrncmp(cmd, "help", 4) == 0)
665 printf("close [<number>] close file [<number>]\n");
666 printf("delete <key> remove record from current file\n");
667 printf("file <number> make file <number> current\n");
668 printf("open <name> open db file\n");
669 printf("q[uit] exit program\n");
670 printf("read <key> read record from current file\n");
671 printf("scan scan current file\n");
672 printf("time time display on/off\n");
673 printf("write <key> <rest-of-line> write record to current file\n");
676 else printf("Eh?\n");
678 if (showtime && stop >= start)
679 printf("start=%d stop=%d difference=%d\n", (int)start, (int)stop,
680 (int)(stop - start));
685 for (i = 0; i < max_db; i++)
687 if (dbblock[i].dbptr != NULL)
689 printf("\nClosing %d", i);
690 dbfn_close(dbblock + i);