summaryrefslogtreecommitdiffstats
path: root/src/dbfn.c
diff options
context:
space:
mode:
Diffstat (limited to 'src/dbfn.c')
-rw-r--r--src/dbfn.c681
1 files changed, 681 insertions, 0 deletions
diff --git a/src/dbfn.c b/src/dbfn.c
new file mode 100644
index 0000000..ea94b7f
--- /dev/null
+++ b/src/dbfn.c
@@ -0,0 +1,681 @@
+/*************************************************
+* Exim - an Internet mail transport agent *
+*************************************************/
+
+/* Copyright (c) The Exim Maintainers 2020 - 2022 */
+/* Copyright (c) University of Cambridge 1995 - 2018 */
+/* See the file NOTICE for conditions of use and distribution. */
+
+
+#include "exim.h"
+
+/* We have buffers holding path names for database files.
+PATH_MAX could be used here, but would be wasting memory, as we deal
+with database files like $spooldirectory/db/<name> */
+#define PATHLEN 256
+
+
+/* Functions for accessing Exim's hints database, which consists of a number of
+different DBM files. This module does not contain code for reading DBM files
+for (e.g.) alias expansion. That is all contained within the general search
+functions. As Exim now has support for several DBM interfaces, all the relevant
+functions are called as macros.
+
+All the data in Exim's database is in the nature of *hints*. Therefore it
+doesn't matter if it gets destroyed by accident. These functions are not
+supposed to implement a "safe" database.
+
+Keys are passed in as C strings, and the terminating zero *is* used when
+building the dbm files. This just makes life easier when scanning the files
+sequentially.
+
+Synchronization is required on the database files, and this is achieved by
+means of locking on independent lock files. (Earlier attempts to lock on the
+DBM files themselves were never completely successful.) Since callers may in
+general want to do more than one read or write while holding the lock, there
+are separate open and close functions. However, the calling modules should
+arrange to hold the locks for the bare minimum of time. */
+
+
+
+/*************************************************
+* Open and lock a database file *
+*************************************************/
+
+/* Used for accessing Exim's hints databases.
+
+Arguments:
+ name The single-component name of one of Exim's database files.
+ flags Either O_RDONLY or O_RDWR, indicating the type of open required;
+ O_RDWR implies "create if necessary"
+ dbblock Points to an open_db block to be filled in.
+ lof If TRUE, write to the log for actual open failures (locking failures
+ are always logged).
+ panic If TRUE, panic on failure to create the db directory
+
+Returns: NULL if the open failed, or the locking failed. After locking
+ failures, errno is zero.
+
+ On success, dbblock is returned. This contains the dbm pointer and
+ the fd of the locked lock file.
+
+There are some calls that use O_RDWR|O_CREAT for the flags. Having discovered
+this in December 2005, I'm not sure if this is correct or not, but for the
+moment I haven't changed them.
+*/
+
+open_db *
+dbfn_open(uschar *name, int flags, open_db *dbblock, BOOL lof, BOOL panic)
+{
+int rc, save_errno;
+BOOL read_only = flags == O_RDONLY;
+flock_t lock_data;
+uschar dirname[PATHLEN], filename[PATHLEN];
+
+DEBUG(D_hints_lookup) acl_level++;
+
+/* The first thing to do is to open a separate file on which to lock. This
+ensures that Exim has exclusive use of the database before it even tries to
+open it. Early versions tried to lock on the open database itself, but that
+gave rise to mysterious problems from time to time - it was suspected that some
+DB libraries "do things" on their open() calls which break the interlocking.
+The lock file is never written to, but we open it for writing so we can get a
+write lock if required. If it does not exist, we create it. This is done
+separately so we know when we have done it, because when running as root we
+need to change the ownership - see the bottom of this function. We also try to
+make the directory as well, just in case. We won't be doing this many times
+unnecessarily, because usually the lock file will be there. If the directory
+exists, there is no error. */
+
+snprintf(CS dirname, sizeof(dirname), "%s/db", spool_directory);
+snprintf(CS filename, sizeof(filename), "%s/%s.lockfile", dirname, name);
+
+priv_drop_temp(exim_uid, exim_gid);
+if ((dbblock->lockfd = Uopen(filename, O_RDWR, EXIMDB_LOCKFILE_MODE)) < 0)
+ {
+ (void)directory_make(spool_directory, US"db", EXIMDB_DIRECTORY_MODE, panic);
+ dbblock->lockfd = Uopen(filename, O_RDWR|O_CREAT, EXIMDB_LOCKFILE_MODE);
+ }
+priv_restore();
+
+if (dbblock->lockfd < 0)
+ {
+ log_write(0, LOG_MAIN, "%s",
+ string_open_failed("database lock file %s", filename));
+ errno = 0; /* Indicates locking failure */
+ DEBUG(D_hints_lookup) acl_level--;
+ return NULL;
+ }
+
+/* Now we must get a lock on the opened lock file; do this with a blocking
+lock that times out. */
+
+lock_data.l_type = read_only? F_RDLCK : F_WRLCK;
+lock_data.l_whence = lock_data.l_start = lock_data.l_len = 0;
+
+DEBUG(D_hints_lookup|D_retry|D_route|D_deliver)
+ debug_printf_indent("locking %s\n", filename);
+
+sigalrm_seen = FALSE;
+ALARM(EXIMDB_LOCK_TIMEOUT);
+rc = fcntl(dbblock->lockfd, F_SETLKW, &lock_data);
+ALARM_CLR(0);
+
+if (sigalrm_seen) errno = ETIMEDOUT;
+if (rc < 0)
+ {
+ log_write(0, LOG_MAIN|LOG_PANIC, "Failed to get %s lock for %s: %s",
+ read_only ? "read" : "write", filename,
+ errno == ETIMEDOUT ? "timed out" : strerror(errno));
+ (void)close(dbblock->lockfd);
+ errno = 0; /* Indicates locking failure */
+ DEBUG(D_hints_lookup) acl_level--;
+ return NULL;
+ }
+
+DEBUG(D_hints_lookup) debug_printf_indent("locked %s\n", filename);
+
+/* At this point we have an opened and locked separate lock file, that is,
+exclusive access to the database, so we can go ahead and open it. If we are
+expected to create it, don't do so at first, again so that we can detect
+whether we need to change its ownership (see comments about the lock file
+above.) There have been regular reports of crashes while opening hints
+databases - often this is caused by non-matching db.h and the library. To make
+it easy to pin this down, there are now debug statements on either side of the
+open call. */
+
+snprintf(CS filename, sizeof(filename), "%s/%s", dirname, name);
+
+priv_drop_temp(exim_uid, exim_gid);
+dbblock->dbptr = exim_dbopen(filename, dirname, flags, EXIMDB_MODE);
+if (!dbblock->dbptr && errno == ENOENT && flags == O_RDWR)
+ {
+ DEBUG(D_hints_lookup)
+ debug_printf_indent("%s appears not to exist: trying to create\n", filename);
+ dbblock->dbptr = exim_dbopen(filename, dirname, flags|O_CREAT, EXIMDB_MODE);
+ }
+save_errno = errno;
+priv_restore();
+
+/* If the open has failed, return NULL, leaving errno set. If lof is TRUE,
+log the event - also for debugging - but debug only if the file just doesn't
+exist. */
+
+if (!dbblock->dbptr)
+ {
+ errno = save_errno;
+ if (lof && save_errno != ENOENT)
+ log_write(0, LOG_MAIN, "%s", string_open_failed("DB file %s",
+ filename));
+ else
+ DEBUG(D_hints_lookup)
+ debug_printf_indent("%s\n", CS string_open_failed("DB file %s",
+ filename));
+ (void)close(dbblock->lockfd);
+ errno = save_errno;
+ DEBUG(D_hints_lookup) acl_level--;
+ return NULL;
+ }
+
+DEBUG(D_hints_lookup)
+ debug_printf_indent("opened hints database %s: flags=%s\n", filename,
+ flags == O_RDONLY ? "O_RDONLY"
+ : flags == O_RDWR ? "O_RDWR"
+ : flags == (O_RDWR|O_CREAT) ? "O_RDWR|O_CREAT"
+ : "??");
+
+/* Pass back the block containing the opened database handle and the open fd
+for the lock. */
+
+return dbblock;
+}
+
+
+
+
+/*************************************************
+* Unlock and close a database file *
+*************************************************/
+
+/* Closing a file automatically unlocks it, so after closing the database, just
+close the lock file.
+
+Argument: a pointer to an open database block
+Returns: nothing
+*/
+
+void
+dbfn_close(open_db *dbblock)
+{
+exim_dbclose(dbblock->dbptr);
+(void)close(dbblock->lockfd);
+DEBUG(D_hints_lookup)
+ { debug_printf_indent("closed hints database and lockfile\n"); acl_level--; }
+}
+
+
+
+
+/*************************************************
+* Read from database file *
+*************************************************/
+
+/* Passing back the pointer unchanged is useless, because there is
+no guarantee of alignment. Since all the records used by Exim need
+to be properly aligned to pick out the timestamps, etc., we might as
+well do the copying centrally here.
+
+Most calls don't need the length, so there is a macro called dbfn_read which
+has two arguments; it calls this function adding NULL as the third.
+
+Arguments:
+ dbblock a pointer to an open database block
+ key the key of the record to be read
+ length a pointer to an int into which to return the length, if not NULL
+
+Returns: a pointer to the retrieved record, or
+ NULL if the record is not found
+*/
+
+void *
+dbfn_read_with_length(open_db *dbblock, const uschar *key, int *length)
+{
+void *yield;
+EXIM_DATUM key_datum, result_datum;
+int klen = Ustrlen(key) + 1;
+uschar * key_copy = store_get(klen, key);
+
+memcpy(key_copy, key, klen);
+
+DEBUG(D_hints_lookup) debug_printf_indent("dbfn_read: key=%s\n", key);
+
+exim_datum_init(&key_datum); /* Some DBM libraries require the datum */
+exim_datum_init(&result_datum); /* to be cleared before use. */
+exim_datum_data_set(&key_datum, key_copy);
+exim_datum_size_set(&key_datum, klen);
+
+if (!exim_dbget(dbblock->dbptr, &key_datum, &result_datum)) return NULL;
+
+/* Assume the data store could have been tainted. Properly, we should
+store the taint status with the data. */
+
+yield = store_get(exim_datum_size_get(&result_datum), GET_TAINTED);
+memcpy(yield, exim_datum_data_get(&result_datum), exim_datum_size_get(&result_datum));
+if (length) *length = exim_datum_size_get(&result_datum);
+
+exim_datum_free(&result_datum); /* Some DBM libs require freeing */
+return yield;
+}
+
+
+/* Read a record. If the length is not as expected then delete it, write
+an error log line, delete the record and return NULL.
+Use this for fixed-size records (so not retry or wait records).
+
+Arguments:
+ dbblock a pointer to an open database block
+ key the key of the record to be read
+ length the expected record length
+
+Returns: a pointer to the retrieved record, or
+ NULL if the record is not found/bad
+*/
+
+void *
+dbfn_read_enforce_length(open_db * dbblock, const uschar * key, size_t length)
+{
+int rlen;
+void * yield = dbfn_read_with_length(dbblock, key, &rlen);
+
+if (yield)
+ {
+ if (rlen == length) return yield;
+ log_write(0, LOG_MAIN|LOG_PANIC, "Bad db record size for '%s'", key);
+ dbfn_delete(dbblock, key);
+ }
+return NULL;
+}
+
+
+/*************************************************
+* Write to database file *
+*************************************************/
+
+/*
+Arguments:
+ dbblock a pointer to an open database block
+ key the key of the record to be written
+ ptr a pointer to the record to be written
+ length the length of the record to be written
+
+Returns: the yield of the underlying dbm or db "write" function. If this
+ is dbm, the value is zero for OK.
+*/
+
+int
+dbfn_write(open_db *dbblock, const uschar *key, void *ptr, int length)
+{
+EXIM_DATUM key_datum, value_datum;
+dbdata_generic *gptr = (dbdata_generic *)ptr;
+int klen = Ustrlen(key) + 1;
+uschar * key_copy = store_get(klen, key);
+
+memcpy(key_copy, key, klen);
+gptr->time_stamp = time(NULL);
+
+DEBUG(D_hints_lookup) debug_printf_indent("dbfn_write: key=%s\n", key);
+
+exim_datum_init(&key_datum); /* Some DBM libraries require the datum */
+exim_datum_init(&value_datum); /* to be cleared before use. */
+exim_datum_data_set(&key_datum, key_copy);
+exim_datum_size_set(&key_datum, klen);
+exim_datum_data_set(&value_datum, ptr);
+exim_datum_size_set(&value_datum, length);
+return exim_dbput(dbblock->dbptr, &key_datum, &value_datum);
+}
+
+
+
+/*************************************************
+* Delete record from database file *
+*************************************************/
+
+/*
+Arguments:
+ dbblock a pointer to an open database block
+ key the key of the record to be deleted
+
+Returns: the yield of the underlying dbm or db "delete" function.
+*/
+
+int
+dbfn_delete(open_db *dbblock, const uschar *key)
+{
+int klen = Ustrlen(key) + 1;
+uschar * key_copy = store_get(klen, key);
+EXIM_DATUM key_datum;
+
+DEBUG(D_hints_lookup) debug_printf_indent("dbfn_delete: key=%s\n", key);
+
+memcpy(key_copy, key, klen);
+exim_datum_init(&key_datum); /* Some DBM libraries require clearing */
+exim_datum_data_set(&key_datum, key_copy);
+exim_datum_size_set(&key_datum, klen);
+return exim_dbdel(dbblock->dbptr, &key_datum);
+}
+
+
+
+/*************************************************
+* Scan the keys of a database file *
+*************************************************/
+
+/*
+Arguments:
+ dbblock a pointer to an open database block
+ start TRUE if starting a new scan
+ FALSE if continuing with the current scan
+ cursor a pointer to a pointer to a cursor anchor, for those dbm libraries
+ that use the notion of a cursor
+
+Returns: the next record from the file, or
+ NULL if there are no more
+*/
+
+uschar *
+dbfn_scan(open_db *dbblock, BOOL start, EXIM_CURSOR **cursor)
+{
+EXIM_DATUM key_datum, value_datum;
+uschar *yield;
+
+DEBUG(D_hints_lookup) debug_printf_indent("dbfn_scan\n");
+
+/* Some dbm require an initialization */
+
+if (start) *cursor = exim_dbcreate_cursor(dbblock->dbptr);
+
+exim_datum_init(&key_datum); /* Some DBM libraries require the datum */
+exim_datum_init(&value_datum); /* to be cleared before use. */
+
+yield = exim_dbscan(dbblock->dbptr, &key_datum, &value_datum, start, *cursor)
+ ? US exim_datum_data_get(&key_datum) : NULL;
+
+/* Some dbm require a termination */
+
+if (!yield) exim_dbdelete_cursor(*cursor);
+return yield;
+}
+
+
+
+/*************************************************
+**************************************************
+* Stand-alone test program *
+**************************************************
+*************************************************/
+
+#ifdef STAND_ALONE
+
+int
+main(int argc, char **cargv)
+{
+open_db dbblock[8];
+int max_db = sizeof(dbblock)/sizeof(open_db);
+int current = -1;
+int showtime = 0;
+int i;
+dbdata_wait *dbwait = NULL;
+uschar **argv = USS cargv;
+uschar buffer[256];
+uschar structbuffer[1024];
+
+if (argc != 2)
+ {
+ printf("Usage: test_dbfn directory\n");
+ printf("The subdirectory called \"db\" in the given directory is used for\n");
+ printf("the files used in this test program.\n");
+ return 1;
+ }
+
+/* Initialize */
+
+spool_directory = argv[1];
+debug_selector = D_all - D_memory;
+debug_file = stderr;
+big_buffer = malloc(big_buffer_size);
+
+for (i = 0; i < max_db; i++) dbblock[i].dbptr = NULL;
+
+printf("\nExim's db functions tester: interface type is %s\n", EXIM_DBTYPE);
+printf("DBM library: ");
+
+#ifdef DB_VERSION_STRING
+printf("Berkeley DB: %s\n", DB_VERSION_STRING);
+#elif defined(BTREEVERSION) && defined(HASHVERSION)
+ #ifdef USE_DB
+ printf("probably Berkeley DB version 1.8x (native mode)\n");
+ #else
+ printf("probably Berkeley DB version 1.8x (compatibility mode)\n");
+ #endif
+#elif defined(_DBM_RDONLY) || defined(dbm_dirfno)
+printf("probably ndbm\n");
+#elif defined(USE_TDB)
+printf("using tdb\n");
+#else
+ #ifdef USE_GDBM
+ printf("probably GDBM (native mode)\n");
+ #else
+ printf("probably GDBM (compatibility mode)\n");
+ #endif
+#endif
+
+/* Test the functions */
+
+printf("\nTest the functions\n> ");
+
+while (Ufgets(buffer, 256, stdin) != NULL)
+ {
+ int len = Ustrlen(buffer);
+ int count = 1;
+ clock_t start = 1;
+ clock_t stop = 0;
+ uschar *cmd = buffer;
+ while (len > 0 && isspace((uschar)buffer[len-1])) len--;
+ buffer[len] = 0;
+
+ if (isdigit((uschar)*cmd))
+ {
+ count = Uatoi(cmd);
+ while (isdigit((uschar)*cmd)) cmd++;
+ while (isspace((uschar)*cmd)) cmd++;
+ }
+
+ if (Ustrncmp(cmd, "open", 4) == 0)
+ {
+ int i;
+ open_db *odb;
+ uschar *s = cmd + 4;
+ while (isspace((uschar)*s)) s++;
+
+ for (i = 0; i < max_db; i++)
+ if (dbblock[i].dbptr == NULL) break;
+
+ if (i >= max_db)
+ {
+ printf("Too many open databases\n> ");
+ continue;
+ }
+
+ start = clock();
+ odb = dbfn_open(s, O_RDWR, dbblock + i, TRUE, TRUE);
+ stop = clock();
+
+ if (odb)
+ {
+ current = i;
+ printf("opened %d\n", current);
+ }
+ /* Other error cases will have written messages */
+ else if (errno == ENOENT)
+ {
+ printf("open failed: %s%s\n", strerror(errno),
+ #ifdef USE_DB
+ " (or other Berkeley DB error)"
+ #else
+ ""
+ #endif
+ );
+ }
+ }
+
+ else if (Ustrncmp(cmd, "write", 5) == 0)
+ {
+ int rc = 0;
+ uschar *key = cmd + 5;
+ uschar *data;
+
+ if (current < 0)
+ {
+ printf("No current database\n");
+ continue;
+ }
+
+ while (isspace((uschar)*key)) key++;
+ data = key;
+ while (*data != 0 && !isspace((uschar)*data)) data++;
+ *data++ = 0;
+ while (isspace((uschar)*data)) data++;
+
+ dbwait = (dbdata_wait *)(&structbuffer);
+ Ustrcpy(dbwait->text, data);
+
+ start = clock();
+ while (count-- > 0)
+ rc = dbfn_write(dbblock + current, key, dbwait,
+ Ustrlen(data) + sizeof(dbdata_wait));
+ stop = clock();
+ if (rc != 0) printf("Failed: %s\n", strerror(errno));
+ }
+
+ else if (Ustrncmp(cmd, "read", 4) == 0)
+ {
+ uschar *key = cmd + 4;
+ if (current < 0)
+ {
+ printf("No current database\n");
+ continue;
+ }
+ while (isspace((uschar)*key)) key++;
+ start = clock();
+ while (count-- > 0)
+ dbwait = (dbdata_wait *)dbfn_read_with_length(dbblock+ current, key, NULL);
+ stop = clock();
+ printf("%s\n", (dbwait == NULL)? "<not found>" : CS dbwait->text);
+ }
+
+ else if (Ustrncmp(cmd, "delete", 6) == 0)
+ {
+ uschar *key = cmd + 6;
+ if (current < 0)
+ {
+ printf("No current database\n");
+ continue;
+ }
+ while (isspace((uschar)*key)) key++;
+ dbfn_delete(dbblock + current, key);
+ }
+
+ else if (Ustrncmp(cmd, "scan", 4) == 0)
+ {
+ EXIM_CURSOR *cursor;
+ BOOL startflag = TRUE;
+ uschar *key;
+ uschar keybuffer[256];
+ if (current < 0)
+ {
+ printf("No current database\n");
+ continue;
+ }
+ start = clock();
+ while ((key = dbfn_scan(dbblock + current, startflag, &cursor)) != NULL)
+ {
+ startflag = FALSE;
+ Ustrcpy(keybuffer, key);
+ dbwait = (dbdata_wait *)dbfn_read_with_length(dbblock + current,
+ keybuffer, NULL);
+ printf("%s: %s\n", keybuffer, dbwait->text);
+ }
+ stop = clock();
+ printf("End of scan\n");
+ }
+
+ else if (Ustrncmp(cmd, "close", 5) == 0)
+ {
+ uschar *s = cmd + 5;
+ while (isspace((uschar)*s)) s++;
+ i = Uatoi(s);
+ if (i >= max_db || dbblock[i].dbptr == NULL) printf("Not open\n"); else
+ {
+ start = clock();
+ dbfn_close(dbblock + i);
+ stop = clock();
+ dbblock[i].dbptr = NULL;
+ if (i == current) current = -1;
+ }
+ }
+
+ else if (Ustrncmp(cmd, "file", 4) == 0)
+ {
+ uschar *s = cmd + 4;
+ while (isspace((uschar)*s)) s++;
+ i = Uatoi(s);
+ if (i >= max_db || dbblock[i].dbptr == NULL) printf("Not open\n");
+ else current = i;
+ }
+
+ else if (Ustrncmp(cmd, "time", 4) == 0)
+ {
+ showtime = ~showtime;
+ printf("Timing %s\n", showtime? "on" : "off");
+ }
+
+ else if (Ustrcmp(cmd, "q") == 0 || Ustrncmp(cmd, "quit", 4) == 0) break;
+
+ else if (Ustrncmp(cmd, "help", 4) == 0)
+ {
+ printf("close [<number>] close file [<number>]\n");
+ printf("delete <key> remove record from current file\n");
+ printf("file <number> make file <number> current\n");
+ printf("open <name> open db file\n");
+ printf("q[uit] exit program\n");
+ printf("read <key> read record from current file\n");
+ printf("scan scan current file\n");
+ printf("time time display on/off\n");
+ printf("write <key> <rest-of-line> write record to current file\n");
+ }
+
+ else printf("Eh?\n");
+
+ if (showtime && stop >= start)
+ printf("start=%d stop=%d difference=%d\n", (int)start, (int)stop,
+ (int)(stop - start));
+
+ printf("> ");
+ }
+
+for (i = 0; i < max_db; i++)
+ {
+ if (dbblock[i].dbptr != NULL)
+ {
+ printf("\nClosing %d", i);
+ dbfn_close(dbblock + i);
+ }
+ }
+
+printf("\n");
+return 0;
+}
+
+#endif
+
+/* End of dbfn.c */
generated by cgit v1.2.3 (git 2.39.1) at 2024-05-03 06:14:09 +0000