2 Unix SMB/CIFS implementation.
3 Samba internal messaging functions
4 Copyright (C) Andrew Tridgell 2000
5 Copyright (C) 2001 by Martin Pool
7 This program is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2 of the License, or
10 (at your option) any later version.
12 This program is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with this program; if not, write to the Free Software
19 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
23 @defgroups messages Internal messaging framework
27 This module is used for internal messaging between Samba daemons.
29 The idea is that if a part of Samba wants to do communication with
30 another Samba process then it will do a message_register() of a
31 dispatch function, and use message_send_pid() to send messages to
34 The dispatch function is given the pid of the sender, and it can
35 use that to reply by message_send_pid(). See ping_message() for a
38 This system doesn't have any inherent size limitations but is not
39 very efficient for large messages or when messages are sent in very
46 /* the locking database handle */
47 static TDB_CONTEXT *tdb;
48 static int received_signal;
50 /* change the message version with any incompatible changes in the protocol */
51 #define MESSAGE_VERSION 1
61 /* we have a linked list of dispatch handlers */
62 static struct dispatch_fns {
63 struct dispatch_fns *next, *prev;
65 void (*fn)(int msg_type, pid_t pid, void *buf, size_t len);
68 /****************************************************************************
69 Notifications come in as signals.
70 ****************************************************************************/
72 static void sig_usr1(void)
78 /****************************************************************************
79 A useful function for testing the message system.
80 ****************************************************************************/
82 void ping_message(int msg_type, pid_t src, void *buf, size_t len)
84 char *msg = buf ? buf : "none";
85 DEBUG(1,("INFO: Received PING message from PID %u [%s]\n",(unsigned int)src, msg));
86 message_send_pid(src, MSG_PONG, buf, len, True);
89 /****************************************************************************
90 Return current debug level.
91 ****************************************************************************/
93 void debuglevel_message(int msg_type, pid_t src, void *buf, size_t len)
95 DEBUG(1,("INFO: Received REQ_DEBUGLEVEL message from PID %u\n",(unsigned int)src));
96 message_send_pid(src, MSG_DEBUGLEVEL, DEBUGLEVEL_CLASS, sizeof(DEBUGLEVEL_CLASS), True);
99 /****************************************************************************
100 Initialise the messaging functions.
101 ****************************************************************************/
103 BOOL message_init(void)
105 if (tdb) return True;
107 tdb = tdb_open_log(lock_path("messages.tdb"),
108 0, TDB_CLEAR_IF_FIRST|TDB_DEFAULT,
109 O_RDWR|O_CREAT,0600);
112 DEBUG(0,("ERROR: Failed to initialise messages database\n"));
116 CatchSignal(SIGUSR1, SIGNAL_CAST sig_usr1);
118 message_register(MSG_PING, ping_message);
119 message_register(MSG_REQ_DEBUGLEVEL, debuglevel_message);
124 /*******************************************************************
125 Form a static tdb key from a pid.
126 ******************************************************************/
128 static TDB_DATA message_key_pid(pid_t pid)
133 slprintf(key, sizeof(key)-1, "PID/%d", (int)pid);
135 kbuf.dptr = (char *)key;
136 kbuf.dsize = strlen(key)+1;
140 /****************************************************************************
141 Notify a process that it has a message. If the process doesn't exist
142 then delete its record in the database.
143 ****************************************************************************/
145 static BOOL message_notify(pid_t pid)
147 if (kill(pid, SIGUSR1) == -1) {
148 if (errno == ESRCH) {
149 DEBUG(2,("pid %d doesn't exist - deleting messages record\n", (int)pid));
150 tdb_delete(tdb, message_key_pid(pid));
152 DEBUG(2,("message to process %d failed - %s\n", (int)pid, strerror(errno)));
159 /****************************************************************************
160 Send a message to a particular pid.
161 ****************************************************************************/
163 BOOL message_send_pid(pid_t pid, int msg_type, const void *buf, size_t len,
164 BOOL duplicates_allowed)
168 struct message_rec rec;
171 rec.msg_version = MESSAGE_VERSION;
172 rec.msg_type = msg_type;
174 rec.src = sys_getpid();
177 kbuf = message_key_pid(pid);
179 /* lock the record for the destination */
180 tdb_chainlock(tdb, kbuf);
182 dbuf = tdb_fetch(tdb, kbuf);
185 /* its a new record */
186 p = (void *)malloc(len + sizeof(rec));
189 memcpy(p, &rec, sizeof(rec));
190 if (len > 0) memcpy((void *)((char*)p+sizeof(rec)), buf, len);
193 dbuf.dsize = len + sizeof(rec);
194 tdb_store(tdb, kbuf, dbuf, TDB_REPLACE);
199 if (!duplicates_allowed) {
201 struct message_rec prec;
203 for(ptr = (char *)dbuf.dptr; ptr < dbuf.dptr + dbuf.dsize; ) {
205 * First check if the message header matches, then, if it's a non-zero
206 * sized message, check if the data matches. If so it's a duplicate and
207 * we can discard it. JRA.
210 if (!memcmp(ptr, &rec, sizeof(rec))) {
211 if (!len || (len && !memcmp( ptr + sizeof(rec), buf, len))) {
212 DEBUG(10,("message_send_pid: discarding duplicate message.\n"));
213 SAFE_FREE(dbuf.dptr);
214 tdb_chainunlock(tdb, kbuf);
218 memcpy(&prec, ptr, sizeof(prec));
219 ptr += sizeof(rec) + prec.len;
223 /* we're adding to an existing entry */
224 p = (void *)malloc(dbuf.dsize + len + sizeof(rec));
227 memcpy(p, dbuf.dptr, dbuf.dsize);
228 memcpy((void *)((char*)p+dbuf.dsize), &rec, sizeof(rec));
229 if (len > 0) memcpy((void *)((char*)p+dbuf.dsize+sizeof(rec)), buf, len);
231 SAFE_FREE(dbuf.dptr);
233 dbuf.dsize += len + sizeof(rec);
234 tdb_store(tdb, kbuf, dbuf, TDB_REPLACE);
235 SAFE_FREE(dbuf.dptr);
238 tdb_chainunlock(tdb, kbuf);
239 errno = 0; /* paranoia */
240 return message_notify(pid);
243 tdb_chainunlock(tdb, kbuf);
244 errno = 0; /* paranoia */
248 /****************************************************************************
249 Retrieve the next message for the current process.
250 ****************************************************************************/
252 static BOOL message_recv(int *msg_type, pid_t *src, void **buf, size_t *len)
256 struct message_rec rec;
258 kbuf = message_key_pid(sys_getpid());
260 tdb_chainlock(tdb, kbuf);
262 dbuf = tdb_fetch(tdb, kbuf);
263 if (dbuf.dptr == NULL || dbuf.dsize == 0) goto failed;
265 memcpy(&rec, dbuf.dptr, sizeof(rec));
267 if (rec.msg_version != MESSAGE_VERSION) {
268 DEBUG(0,("message version %d received (expected %d)\n", rec.msg_version, MESSAGE_VERSION));
273 (*buf) = (void *)malloc(rec.len);
274 if (!(*buf)) goto failed;
276 memcpy(*buf, dbuf.dptr+sizeof(rec), rec.len);
282 *msg_type = rec.msg_type;
285 if (dbuf.dsize - (sizeof(rec)+rec.len) > 0)
286 memmove(dbuf.dptr, dbuf.dptr+sizeof(rec)+rec.len, dbuf.dsize - (sizeof(rec)+rec.len));
287 dbuf.dsize -= sizeof(rec)+rec.len;
290 tdb_delete(tdb, kbuf);
292 tdb_store(tdb, kbuf, dbuf, TDB_REPLACE);
294 SAFE_FREE(dbuf.dptr);
295 tdb_chainunlock(tdb, kbuf);
299 tdb_chainunlock(tdb, kbuf);
303 /****************************************************************************
304 Receive and dispatch any messages pending for this process.
305 Notice that all dispatch handlers for a particular msg_type get called,
306 so you can register multiple handlers for a message.
307 ****************************************************************************/
309 void message_dispatch(void)
315 struct dispatch_fns *dfn;
318 if (!received_signal) return;
320 DEBUG(10,("message_dispatch: received_signal = %d\n", received_signal));
324 while (message_recv(&msg_type, &src, &buf, &len)) {
325 DEBUG(10,("message_dispatch: received msg_type=%d src_pid=%d\n",
326 msg_type, (int) src));
328 for (dfn = dispatch_fns; dfn; dfn = dfn->next) {
329 if (dfn->msg_type == msg_type) {
330 DEBUG(10,("message_dispatch: processing message of type %d.\n", msg_type));
331 dfn->fn(msg_type, src, buf, len);
336 DEBUG(5,("message_dispatch: warning: no handlers registed for "
337 "msg_type %d in pid%d\n",
338 msg_type, getpid()));
344 /****************************************************************************
345 Register a dispatch function for a particular message type.
346 ****************************************************************************/
348 void message_register(int msg_type,
349 void (*fn)(int msg_type, pid_t pid, void *buf, size_t len))
351 struct dispatch_fns *dfn;
353 dfn = (struct dispatch_fns *)malloc(sizeof(*dfn));
359 dfn->msg_type = msg_type;
362 DLIST_ADD(dispatch_fns, dfn);
366 DEBUG(0,("message_register: Not enough memory. malloc failed!\n"));
370 /****************************************************************************
371 De-register the function for a particular message type.
372 ****************************************************************************/
374 void message_deregister(int msg_type)
376 struct dispatch_fns *dfn, *next;
378 for (dfn = dispatch_fns; dfn; dfn = next) {
380 if (dfn->msg_type == msg_type) {
381 DLIST_REMOVE(dispatch_fns, dfn);
395 /****************************************************************************
396 Send one of the messages for the broadcast.
397 ****************************************************************************/
399 static int traverse_fn(TDB_CONTEXT *the_tdb, TDB_DATA kbuf, TDB_DATA dbuf, void *state)
401 struct connections_data crec;
402 struct msg_all *msg_all = (struct msg_all *)state;
404 if (dbuf.dsize != sizeof(crec))
407 memcpy(&crec, dbuf.dptr, sizeof(crec));
412 /* if the msg send fails because the pid was not found (i.e. smbd died),
413 * the msg has already been deleted from the messages.tdb.*/
414 if (!message_send_pid(crec.pid, msg_all->msg_type,
415 msg_all->buf, msg_all->len,
416 msg_all->duplicates)) {
418 /* if the pid was not found delete the entry from connections.tdb */
419 if (errno == ESRCH) {
420 DEBUG(2,("pid %u doesn't exist - deleting connections %d [%s]\n",
421 (unsigned int)crec.pid, crec.cnum, crec.name));
422 tdb_delete(the_tdb, kbuf);
430 * Send a message to all smbd processes.
432 * It isn't very efficient, but should be OK for the sorts of
433 * applications that use it. When we need efficient broadcast we can add
436 * @param n_sent Set to the number of messages sent. This should be
437 * equal to the number of processes, but be careful for races.
439 * @return True for success.
441 BOOL message_send_all(TDB_CONTEXT *conn_tdb, int msg_type,
442 const void *buf, size_t len,
443 BOOL duplicates_allowed,
446 struct msg_all msg_all;
448 msg_all.msg_type = msg_type;
451 msg_all.duplicates = duplicates_allowed;
454 tdb_traverse(conn_tdb, traverse_fn, &msg_all);
456 *n_sent = msg_all.n_sent;
464 lock the messaging tdb based on a string - this is used as a primitive form of mutex
465 between smbd instances.
467 BOOL message_named_mutex(const char *name)
471 if (!message_init()) return False;
474 key.dsize = strlen(name)+1;
476 return (tdb_chainlock(tdb, key) == 0);
482 void message_named_mutex_release(const char *name)
487 key.dsize = strlen(name)+1;
489 tdb_chainunlock(tdb, key);