2 Unix SMB/CIFS implementation.
3 Samba internal messaging functions
4 Copyright (C) Andrew Tridgell 2000
5 Copyright (C) 2001 by Martin Pool
6 Copyright (C) 2002 by Jeremy Allison
8 This program is free software; you can redistribute it and/or modify
9 it under the terms of the GNU General Public License as published by
10 the Free Software Foundation; either version 2 of the License, or
11 (at your option) any later version.
13 This program is distributed in the hope that it will be useful,
14 but WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 GNU General Public License for more details.
18 You should have received a copy of the GNU General Public License
19 along with this program; if not, write to the Free Software
20 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
24 @defgroup messages Internal messaging framework
28 @brief Module for internal messaging between Samba daemons.
30 The idea is that if a part of Samba wants to do communication with
31 another Samba process then it will do a message_register() of a
32 dispatch function, and use message_send_pid() to send messages to
35 The dispatch function is given the pid of the sender, and it can
36 use that to reply by message_send_pid(). See ping_message() for a
39 @caution Dispatch functions must be able to cope with incoming
40 messages on an *odd* byte boundary.
42 This system doesn't have any inherent size limitations but is not
43 very efficient for large messages or when messages are sent in very
50 /* the locking database handle */
51 static TDB_CONTEXT *tdb;
52 static int received_signal;
54 /* change the message version with any incompatible changes in the protocol */
55 #define MESSAGE_VERSION 1
65 /* we have a linked list of dispatch handlers */
66 static struct dispatch_fns {
67 struct dispatch_fns *next, *prev;
69 void (*fn)(int msg_type, pid_t pid, void *buf, size_t len);
72 /****************************************************************************
73 Notifications come in as signals.
74 ****************************************************************************/
76 static void sig_usr1(void)
82 /****************************************************************************
83 A useful function for testing the message system.
84 ****************************************************************************/
86 static void ping_message(int msg_type, pid_t src, void *buf, size_t len)
88 const char *msg = buf ? buf : "none";
89 DEBUG(1,("INFO: Received PING message from PID %u [%s]\n",(unsigned int)src, msg));
90 message_send_pid(src, MSG_PONG, buf, len, True);
93 /****************************************************************************
94 Initialise the messaging functions.
95 ****************************************************************************/
97 BOOL message_init(void)
101 tdb = tdb_open_log(lock_path("messages.tdb"),
102 0, TDB_CLEAR_IF_FIRST|TDB_DEFAULT,
103 O_RDWR|O_CREAT,0600);
106 DEBUG(0,("ERROR: Failed to initialise messages database\n"));
110 CatchSignal(SIGUSR1, SIGNAL_CAST sig_usr1);
112 message_register(MSG_PING, ping_message);
114 /* Register some debugging related messages */
116 register_msg_pool_usage();
117 register_dmalloc_msgs();
122 /*******************************************************************
123 Form a static tdb key from a pid.
124 ******************************************************************/
126 static TDB_DATA message_key_pid(pid_t pid)
131 slprintf(key, sizeof(key)-1, "PID/%d", (int)pid);
133 kbuf.dptr = (char *)key;
134 kbuf.dsize = strlen(key)+1;
138 /****************************************************************************
139 Notify a process that it has a message. If the process doesn't exist
140 then delete its record in the database.
141 ****************************************************************************/
143 static BOOL message_notify(pid_t pid)
146 * Doing kill with a non-positive pid causes messages to be
147 * sent to places we don't want.
152 if (kill(pid, SIGUSR1) == -1) {
153 if (errno == ESRCH) {
154 DEBUG(2,("pid %d doesn't exist - deleting messages record\n", (int)pid));
155 tdb_delete(tdb, message_key_pid(pid));
157 DEBUG(2,("message to process %d failed - %s\n", (int)pid, strerror(errno)));
164 /****************************************************************************
165 Send a message to a particular pid.
166 ****************************************************************************/
168 static BOOL message_send_pid_internal(pid_t pid, int msg_type, const void *buf, size_t len,
169 BOOL duplicates_allowed, unsigned int timeout)
174 struct message_rec rec;
176 struct message_rec prec;
179 * Doing kill with a non-positive pid causes messages to be
180 * sent to places we don't want.
185 rec.msg_version = MESSAGE_VERSION;
186 rec.msg_type = msg_type;
188 rec.src = sys_getpid();
191 kbuf = message_key_pid(pid);
193 dbuf.dptr = (void *)SMB_MALLOC(len + sizeof(rec));
197 memcpy(dbuf.dptr, &rec, sizeof(rec));
199 memcpy((void *)((char*)dbuf.dptr+sizeof(rec)), buf, len);
201 dbuf.dsize = len + sizeof(rec);
203 if (duplicates_allowed) {
205 /* If duplicates are allowed we can just append the message and return. */
207 /* lock the record for the destination */
209 if (tdb_chainlock_with_timeout(tdb, kbuf, timeout) == -1) {
210 DEBUG(0,("message_send_pid_internal: failed to get chainlock with timeout %ul.\n", timeout));
214 if (tdb_chainlock(tdb, kbuf) == -1) {
215 DEBUG(0,("message_send_pid_internal: failed to get chainlock.\n"));
219 tdb_append(tdb, kbuf, dbuf);
220 tdb_chainunlock(tdb, kbuf);
222 SAFE_FREE(dbuf.dptr);
223 errno = 0; /* paranoia */
224 return message_notify(pid);
227 /* lock the record for the destination */
229 if (tdb_chainlock_with_timeout(tdb, kbuf, timeout) == -1) {
230 DEBUG(0,("message_send_pid_internal: failed to get chainlock with timeout %ul.\n", timeout));
234 if (tdb_chainlock(tdb, kbuf) == -1) {
235 DEBUG(0,("message_send_pid_internal: failed to get chainlock.\n"));
240 old_dbuf = tdb_fetch(tdb, kbuf);
242 if (!old_dbuf.dptr) {
243 /* its a new record */
245 tdb_store(tdb, kbuf, dbuf, TDB_REPLACE);
246 tdb_chainunlock(tdb, kbuf);
248 SAFE_FREE(dbuf.dptr);
249 errno = 0; /* paranoia */
250 return message_notify(pid);
253 /* Not a new record. Check for duplicates. */
255 for(ptr = (char *)old_dbuf.dptr; ptr < old_dbuf.dptr + old_dbuf.dsize; ) {
257 * First check if the message header matches, then, if it's a non-zero
258 * sized message, check if the data matches. If so it's a duplicate and
259 * we can discard it. JRA.
262 if (!memcmp(ptr, &rec, sizeof(rec))) {
263 if (!len || (len && !memcmp( ptr + sizeof(rec), buf, len))) {
264 tdb_chainunlock(tdb, kbuf);
265 DEBUG(10,("message_send_pid_internal: discarding duplicate message.\n"));
266 SAFE_FREE(dbuf.dptr);
267 SAFE_FREE(old_dbuf.dptr);
271 memcpy(&prec, ptr, sizeof(prec));
272 ptr += sizeof(rec) + prec.len;
275 /* we're adding to an existing entry */
277 tdb_append(tdb, kbuf, dbuf);
278 tdb_chainunlock(tdb, kbuf);
280 SAFE_FREE(old_dbuf.dptr);
281 SAFE_FREE(dbuf.dptr);
283 errno = 0; /* paranoia */
284 return message_notify(pid);
287 /****************************************************************************
288 Send a message to a particular pid - no timeout.
289 ****************************************************************************/
291 BOOL message_send_pid(pid_t pid, int msg_type, const void *buf, size_t len, BOOL duplicates_allowed)
293 return message_send_pid_internal(pid, msg_type, buf, len, duplicates_allowed, 0);
296 /****************************************************************************
297 Send a message to a particular pid, with timeout in seconds.
298 ****************************************************************************/
300 BOOL message_send_pid_with_timeout(pid_t pid, int msg_type, const void *buf, size_t len,
301 BOOL duplicates_allowed, unsigned int timeout)
303 return message_send_pid_internal(pid, msg_type, buf, len, duplicates_allowed, timeout);
306 /****************************************************************************
307 Count the messages pending for a particular pid. Expensive....
308 ****************************************************************************/
310 unsigned int messages_pending_for_pid(pid_t pid)
315 unsigned int message_count = 0;
317 kbuf = message_key_pid(sys_getpid());
319 dbuf = tdb_fetch(tdb, kbuf);
320 if (dbuf.dptr == NULL || dbuf.dsize == 0) {
321 SAFE_FREE(dbuf.dptr);
325 for (buf = dbuf.dptr; dbuf.dsize > sizeof(struct message_rec);) {
326 struct message_rec rec;
327 memcpy(&rec, buf, sizeof(rec));
328 buf += (sizeof(rec) + rec.len);
329 dbuf.dsize -= (sizeof(rec) + rec.len);
333 SAFE_FREE(dbuf.dptr);
334 return message_count;
337 /****************************************************************************
338 Retrieve all messages for the current process.
339 ****************************************************************************/
341 static BOOL retrieve_all_messages(char **msgs_buf, size_t *total_len)
347 ZERO_STRUCT(null_dbuf);
352 kbuf = message_key_pid(sys_getpid());
354 if (tdb_chainlock(tdb, kbuf) == -1)
357 dbuf = tdb_fetch(tdb, kbuf);
359 * Replace with an empty record to keep the allocated
362 tdb_store(tdb, kbuf, null_dbuf, TDB_REPLACE);
363 tdb_chainunlock(tdb, kbuf);
365 if (dbuf.dptr == NULL || dbuf.dsize == 0) {
366 SAFE_FREE(dbuf.dptr);
370 *msgs_buf = dbuf.dptr;
371 *total_len = dbuf.dsize;
376 /****************************************************************************
377 Parse out the next message for the current process.
378 ****************************************************************************/
380 static BOOL message_recv(char *msgs_buf, size_t total_len, int *msg_type, pid_t *src, char **buf, size_t *len)
382 struct message_rec rec;
383 char *ret_buf = *buf;
388 if (total_len - (ret_buf - msgs_buf) < sizeof(rec))
391 memcpy(&rec, ret_buf, sizeof(rec));
392 ret_buf += sizeof(rec);
394 if (rec.msg_version != MESSAGE_VERSION) {
395 DEBUG(0,("message version %d received (expected %d)\n", rec.msg_version, MESSAGE_VERSION));
400 if (total_len - (ret_buf - msgs_buf) < rec.len)
405 *msg_type = rec.msg_type;
412 /****************************************************************************
413 Receive and dispatch any messages pending for this process.
414 Notice that all dispatch handlers for a particular msg_type get called,
415 so you can register multiple handlers for a message.
416 *NOTE*: Dispatch functions must be able to cope with incoming
417 messages on an *odd* byte boundary.
418 ****************************************************************************/
420 void message_dispatch(void)
426 size_t len, total_len;
427 struct dispatch_fns *dfn;
430 if (!received_signal)
433 DEBUG(10,("message_dispatch: received_signal = %d\n", received_signal));
437 if (!retrieve_all_messages(&msgs_buf, &total_len))
440 for (buf = msgs_buf; message_recv(msgs_buf, total_len, &msg_type, &src, &buf, &len); buf += len) {
441 DEBUG(10,("message_dispatch: received msg_type=%d src_pid=%u\n",
442 msg_type, (unsigned int) src));
444 for (dfn = dispatch_fns; dfn; dfn = dfn->next) {
445 if (dfn->msg_type == msg_type) {
446 DEBUG(10,("message_dispatch: processing message of type %d.\n", msg_type));
447 dfn->fn(msg_type, src, len ? (void *)buf : NULL, len);
452 DEBUG(5,("message_dispatch: warning: no handlers registed for "
453 "msg_type %d in pid %u\n",
454 msg_type, (unsigned int)sys_getpid()));
460 /****************************************************************************
461 Register a dispatch function for a particular message type.
462 *NOTE*: Dispatch functions must be able to cope with incoming
463 messages on an *odd* byte boundary.
464 ****************************************************************************/
466 void message_register(int msg_type,
467 void (*fn)(int msg_type, pid_t pid, void *buf, size_t len))
469 struct dispatch_fns *dfn;
471 dfn = SMB_MALLOC_P(struct dispatch_fns);
477 dfn->msg_type = msg_type;
480 DLIST_ADD(dispatch_fns, dfn);
484 DEBUG(0,("message_register: Not enough memory. malloc failed!\n"));
488 /****************************************************************************
489 De-register the function for a particular message type.
490 ****************************************************************************/
492 void message_deregister(int msg_type)
494 struct dispatch_fns *dfn, *next;
496 for (dfn = dispatch_fns; dfn; dfn = next) {
498 if (dfn->msg_type == msg_type) {
499 DLIST_REMOVE(dispatch_fns, dfn);
514 /****************************************************************************
515 Send one of the messages for the broadcast.
516 ****************************************************************************/
518 static int traverse_fn(TDB_CONTEXT *the_tdb, TDB_DATA kbuf, TDB_DATA dbuf, void *state)
520 struct connections_data crec;
521 struct msg_all *msg_all = (struct msg_all *)state;
523 if (dbuf.dsize != sizeof(crec))
526 memcpy(&crec, dbuf.dptr, sizeof(crec));
531 /* Don't send if the receiver hasn't registered an interest. */
533 if(!(crec.bcast_msg_flags & msg_all->msg_flag))
536 /* If the msg send fails because the pid was not found (i.e. smbd died),
537 * the msg has already been deleted from the messages.tdb.*/
539 if (!message_send_pid(crec.pid, msg_all->msg_type,
540 msg_all->buf, msg_all->len,
541 msg_all->duplicates)) {
543 /* If the pid was not found delete the entry from connections.tdb */
545 if (errno == ESRCH) {
546 DEBUG(2,("pid %u doesn't exist - deleting connections %d [%s]\n",
547 (unsigned int)crec.pid, crec.cnum, crec.name));
548 tdb_delete(the_tdb, kbuf);
556 * Send a message to all smbd processes.
558 * It isn't very efficient, but should be OK for the sorts of
559 * applications that use it. When we need efficient broadcast we can add
562 * @param n_sent Set to the number of messages sent. This should be
563 * equal to the number of processes, but be careful for races.
565 * @retval True for success.
567 BOOL message_send_all(TDB_CONTEXT *conn_tdb, int msg_type,
568 const void *buf, size_t len,
569 BOOL duplicates_allowed,
572 struct msg_all msg_all;
574 msg_all.msg_type = msg_type;
576 msg_all.msg_flag = FLAG_MSG_GENERAL;
577 else if (msg_type > 1000 && msg_type < 2000)
578 msg_all.msg_flag = FLAG_MSG_NMBD;
579 else if (msg_type > 2000 && msg_type < 2100)
580 msg_all.msg_flag = FLAG_MSG_PRINT_NOTIFY;
581 else if (msg_type > 2100 && msg_type < 3000)
582 msg_all.msg_flag = FLAG_MSG_PRINT_GENERAL;
583 else if (msg_type > 3000 && msg_type < 4000)
584 msg_all.msg_flag = FLAG_MSG_SMBD;
590 msg_all.duplicates = duplicates_allowed;
593 tdb_traverse(conn_tdb, traverse_fn, &msg_all);
595 *n_sent = msg_all.n_sent;