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 @defgroups messages Internal messaging framework
28 This module is used 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 *NOTE*: 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);
117 /*******************************************************************
118 Form a static tdb key from a pid.
119 ******************************************************************/
121 static TDB_DATA message_key_pid(pid_t pid)
126 slprintf(key, sizeof(key)-1, "PID/%d", (int)pid);
128 kbuf.dptr = (char *)key;
129 kbuf.dsize = strlen(key)+1;
133 /****************************************************************************
134 Notify a process that it has a message. If the process doesn't exist
135 then delete its record in the database.
136 ****************************************************************************/
138 static BOOL message_notify(pid_t pid)
141 * Doing kill with a non-positive pid causes messages to be
142 * sent to places we don't want.
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 static BOOL message_send_pid_internal(pid_t pid, int msg_type, const void *buf, size_t len,
164 BOOL duplicates_allowed, unsigned int timeout)
169 struct message_rec rec;
171 struct message_rec prec;
174 * Doing kill with a non-positive pid causes messages to be
175 * sent to places we don't want.
180 rec.msg_version = MESSAGE_VERSION;
181 rec.msg_type = msg_type;
183 rec.src = sys_getpid();
186 kbuf = message_key_pid(pid);
188 dbuf.dptr = (void *)malloc(len + sizeof(rec));
192 memcpy(dbuf.dptr, &rec, sizeof(rec));
194 memcpy((void *)((char*)dbuf.dptr+sizeof(rec)), buf, len);
196 dbuf.dsize = len + sizeof(rec);
198 if (duplicates_allowed) {
200 /* If duplicates are allowed we can just append the message and return. */
202 /* lock the record for the destination */
204 if (tdb_chainlock_with_timeout(tdb, kbuf, timeout) == -1) {
205 DEBUG(0,("message_send_pid_internal: failed to get chainlock with timeout %ul.\n", timeout));
209 if (tdb_chainlock(tdb, kbuf) == -1) {
210 DEBUG(0,("message_send_pid_internal: failed to get chainlock.\n"));
214 tdb_append(tdb, kbuf, dbuf);
215 tdb_chainunlock(tdb, kbuf);
217 SAFE_FREE(dbuf.dptr);
218 errno = 0; /* paranoia */
219 return message_notify(pid);
222 /* lock the record for the destination */
224 if (tdb_chainlock_with_timeout(tdb, kbuf, timeout) == -1) {
225 DEBUG(0,("message_send_pid_internal: failed to get chainlock with timeout %ul.\n", timeout));
229 if (tdb_chainlock(tdb, kbuf) == -1) {
230 DEBUG(0,("message_send_pid_internal: failed to get chainlock.\n"));
235 old_dbuf = tdb_fetch(tdb, kbuf);
237 if (!old_dbuf.dptr) {
238 /* its a new record */
240 tdb_store(tdb, kbuf, dbuf, TDB_REPLACE);
241 tdb_chainunlock(tdb, kbuf);
243 SAFE_FREE(dbuf.dptr);
244 errno = 0; /* paranoia */
245 return message_notify(pid);
248 /* Not a new record. Check for duplicates. */
250 for(ptr = (char *)old_dbuf.dptr; ptr < old_dbuf.dptr + old_dbuf.dsize; ) {
252 * First check if the message header matches, then, if it's a non-zero
253 * sized message, check if the data matches. If so it's a duplicate and
254 * we can discard it. JRA.
257 if (!memcmp(ptr, &rec, sizeof(rec))) {
258 if (!len || (len && !memcmp( ptr + sizeof(rec), buf, len))) {
259 tdb_chainunlock(tdb, kbuf);
260 DEBUG(10,("message_send_pid_internal: discarding duplicate message.\n"));
261 SAFE_FREE(dbuf.dptr);
262 SAFE_FREE(old_dbuf.dptr);
266 memcpy(&prec, ptr, sizeof(prec));
267 ptr += sizeof(rec) + prec.len;
270 /* we're adding to an existing entry */
272 tdb_append(tdb, kbuf, dbuf);
273 tdb_chainunlock(tdb, kbuf);
275 SAFE_FREE(old_dbuf.dptr);
276 SAFE_FREE(dbuf.dptr);
278 errno = 0; /* paranoia */
279 return message_notify(pid);
282 /****************************************************************************
283 Send a message to a particular pid - no timeout.
284 ****************************************************************************/
286 BOOL message_send_pid(pid_t pid, int msg_type, const void *buf, size_t len, BOOL duplicates_allowed)
288 return message_send_pid_internal(pid, msg_type, buf, len, duplicates_allowed, 0);
291 /****************************************************************************
292 Send a message to a particular pid, with timeout in seconds.
293 ****************************************************************************/
295 BOOL message_send_pid_with_timeout(pid_t pid, int msg_type, const void *buf, size_t len,
296 BOOL duplicates_allowed, unsigned int timeout)
298 return message_send_pid_internal(pid, msg_type, buf, len, duplicates_allowed, timeout);
301 /****************************************************************************
302 Retrieve all messages for the current process.
303 ****************************************************************************/
305 static BOOL retrieve_all_messages(char **msgs_buf, size_t *total_len)
311 ZERO_STRUCT(null_dbuf);
316 kbuf = message_key_pid(sys_getpid());
318 tdb_chainlock(tdb, kbuf);
319 dbuf = tdb_fetch(tdb, kbuf);
321 * Replace with an empty record to keep the allocated
324 tdb_store(tdb, kbuf, null_dbuf, TDB_REPLACE);
325 tdb_chainunlock(tdb, kbuf);
327 if (dbuf.dptr == NULL || dbuf.dsize == 0) {
328 SAFE_FREE(dbuf.dptr);
332 *msgs_buf = dbuf.dptr;
333 *total_len = dbuf.dsize;
338 /****************************************************************************
339 Parse out the next message for the current process.
340 ****************************************************************************/
342 static BOOL message_recv(char *msgs_buf, size_t total_len, int *msg_type, pid_t *src, char **buf, size_t *len)
344 struct message_rec rec;
345 char *ret_buf = *buf;
350 if (total_len - (ret_buf - msgs_buf) < sizeof(rec))
353 memcpy(&rec, ret_buf, sizeof(rec));
354 ret_buf += sizeof(rec);
356 if (rec.msg_version != MESSAGE_VERSION) {
357 DEBUG(0,("message version %d received (expected %d)\n", rec.msg_version, MESSAGE_VERSION));
362 if (total_len - (ret_buf - msgs_buf) < rec.len)
367 *msg_type = rec.msg_type;
374 /****************************************************************************
375 Receive and dispatch any messages pending for this process.
376 Notice that all dispatch handlers for a particular msg_type get called,
377 so you can register multiple handlers for a message.
378 *NOTE*: Dispatch functions must be able to cope with incoming
379 messages on an *odd* byte boundary.
380 ****************************************************************************/
382 void message_dispatch(void)
388 size_t len, total_len;
389 struct dispatch_fns *dfn;
392 if (!received_signal)
395 DEBUG(10,("message_dispatch: received_signal = %d\n", received_signal));
399 if (!retrieve_all_messages(&msgs_buf, &total_len))
402 for (buf = msgs_buf; message_recv(msgs_buf, total_len, &msg_type, &src, &buf, &len); buf += len) {
403 DEBUG(10,("message_dispatch: received msg_type=%d src_pid=%u\n",
404 msg_type, (unsigned int) src));
406 for (dfn = dispatch_fns; dfn; dfn = dfn->next) {
407 if (dfn->msg_type == msg_type) {
408 DEBUG(10,("message_dispatch: processing message of type %d.\n", msg_type));
409 dfn->fn(msg_type, src, len ? (void *)buf : NULL, len);
414 DEBUG(5,("message_dispatch: warning: no handlers registed for "
415 "msg_type %d in pid %u\n",
416 msg_type, (unsigned int)sys_getpid()));
422 /****************************************************************************
423 Register a dispatch function for a particular message type.
424 *NOTE*: Dispatch functions must be able to cope with incoming
425 messages on an *odd* byte boundary.
426 ****************************************************************************/
428 void message_register(int msg_type,
429 void (*fn)(int msg_type, pid_t pid, void *buf, size_t len))
431 struct dispatch_fns *dfn;
433 dfn = (struct dispatch_fns *)malloc(sizeof(*dfn));
439 dfn->msg_type = msg_type;
442 DLIST_ADD(dispatch_fns, dfn);
446 DEBUG(0,("message_register: Not enough memory. malloc failed!\n"));
450 /****************************************************************************
451 De-register the function for a particular message type.
452 ****************************************************************************/
454 void message_deregister(int msg_type)
456 struct dispatch_fns *dfn, *next;
458 for (dfn = dispatch_fns; dfn; dfn = next) {
460 if (dfn->msg_type == msg_type) {
461 DLIST_REMOVE(dispatch_fns, dfn);
476 /****************************************************************************
477 Send one of the messages for the broadcast.
478 ****************************************************************************/
480 static int traverse_fn(TDB_CONTEXT *the_tdb, TDB_DATA kbuf, TDB_DATA dbuf, void *state)
482 struct connections_data crec;
483 struct msg_all *msg_all = (struct msg_all *)state;
485 if (dbuf.dsize != sizeof(crec))
488 memcpy(&crec, dbuf.dptr, sizeof(crec));
493 /* Don't send if the receiver hasn't registered an interest. */
495 if(!(crec.bcast_msg_flags & msg_all->msg_flag))
498 /* If the msg send fails because the pid was not found (i.e. smbd died),
499 * the msg has already been deleted from the messages.tdb.*/
501 if (!message_send_pid(crec.pid, msg_all->msg_type,
502 msg_all->buf, msg_all->len,
503 msg_all->duplicates)) {
505 /* If the pid was not found delete the entry from connections.tdb */
507 if (errno == ESRCH) {
508 DEBUG(2,("pid %u doesn't exist - deleting connections %d [%s]\n",
509 (unsigned int)crec.pid, crec.cnum, crec.name));
510 tdb_delete(the_tdb, kbuf);
518 * Send a message to all smbd processes.
520 * It isn't very efficient, but should be OK for the sorts of
521 * applications that use it. When we need efficient broadcast we can add
524 * @param n_sent Set to the number of messages sent. This should be
525 * equal to the number of processes, but be careful for races.
527 * @return True for success.
529 BOOL message_send_all(TDB_CONTEXT *conn_tdb, int msg_type,
530 const void *buf, size_t len,
531 BOOL duplicates_allowed,
534 struct msg_all msg_all;
536 msg_all.msg_type = msg_type;
538 msg_all.msg_flag = FLAG_MSG_GENERAL;
539 else if (msg_type > 1000 && msg_type < 2000)
540 msg_all.msg_flag = FLAG_MSG_NMBD;
541 else if (msg_type > 2000 && msg_type < 3000)
542 msg_all.msg_flag = FLAG_MSG_PRINTING;
543 else if (msg_type > 3000 && msg_type < 4000)
544 msg_all.msg_flag = FLAG_MSG_SMBD;
550 msg_all.duplicates = duplicates_allowed;
553 tdb_traverse(conn_tdb, traverse_fn, &msg_all);
555 *n_sent = msg_all.n_sent;