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
60 struct process_id dest
;
61 struct process_id src
;
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
, struct process_id pid
, void *buf
, size_t len
);
72 /****************************************************************************
73 Notifications come in as signals.
74 ****************************************************************************/
76 static void sig_usr1(void)
79 sys_select_signal(SIGUSR1
);
82 /****************************************************************************
83 A useful function for testing the message system.
84 ****************************************************************************/
86 static void ping_message(int msg_type
, struct process_id src
,
87 void *buf
, size_t len
)
89 const char *msg
= buf
? buf
: "none";
90 DEBUG(1,("INFO: Received PING message from PID %s [%s]\n",
91 procid_str_static(&src
), msg
));
92 message_send_pid(src
, MSG_PONG
, buf
, len
, True
);
95 /****************************************************************************
96 Initialise the messaging functions.
97 ****************************************************************************/
99 BOOL
message_init(void)
101 if (tdb
) return True
;
103 tdb
= tdb_open_log(lock_path("messages.tdb"),
104 0, TDB_CLEAR_IF_FIRST
|TDB_DEFAULT
,
105 O_RDWR
|O_CREAT
,0600);
108 DEBUG(0,("ERROR: Failed to initialise messages database\n"));
112 CatchSignal(SIGUSR1
, SIGNAL_CAST sig_usr1
);
114 message_register(MSG_PING
, ping_message
);
116 /* Register some debugging related messages */
118 register_msg_pool_usage();
119 register_dmalloc_msgs();
124 /*******************************************************************
125 Form a static tdb key from a pid.
126 ******************************************************************/
128 static TDB_DATA
message_key_pid(struct process_id pid
)
133 slprintf(key
, sizeof(key
)-1, "PID/%s", procid_str_static(&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(struct process_id procid
)
147 pid_t pid
= procid
.pid
;
149 * Doing kill with a non-positive pid causes messages to be
150 * sent to places we don't want.
155 if (kill(pid
, SIGUSR1
) == -1) {
156 if (errno
== ESRCH
) {
157 DEBUG(2,("pid %d doesn't exist - deleting messages record\n", (int)pid
));
158 tdb_delete(tdb
, message_key_pid(procid
));
160 DEBUG(2,("message to process %d failed - %s\n", (int)pid
, strerror(errno
)));
167 /****************************************************************************
168 Send a message to a particular pid.
169 ****************************************************************************/
171 static BOOL
message_send_pid_internal(struct process_id pid
, int msg_type
,
172 const void *buf
, size_t len
,
173 BOOL duplicates_allowed
,
174 unsigned int timeout
)
179 struct message_rec rec
;
181 struct message_rec prec
;
184 * Doing kill with a non-positive pid causes messages to be
185 * sent to places we don't want.
188 SMB_ASSERT(procid_to_pid(&pid
) > 0);
190 rec
.msg_version
= MESSAGE_VERSION
;
191 rec
.msg_type
= msg_type
;
193 rec
.src
= procid_self();
196 kbuf
= message_key_pid(pid
);
198 dbuf
.dptr
= (void *)SMB_MALLOC(len
+ sizeof(rec
));
202 memcpy(dbuf
.dptr
, &rec
, sizeof(rec
));
204 memcpy((void *)((char*)dbuf
.dptr
+sizeof(rec
)), buf
, len
);
206 dbuf
.dsize
= len
+ sizeof(rec
);
208 if (duplicates_allowed
) {
210 /* If duplicates are allowed we can just append the message and return. */
212 /* lock the record for the destination */
214 if (tdb_chainlock_with_timeout(tdb
, kbuf
, timeout
) == -1) {
215 DEBUG(0,("message_send_pid_internal: failed to get chainlock with timeout %ul.\n", timeout
));
219 if (tdb_chainlock(tdb
, kbuf
) == -1) {
220 DEBUG(0,("message_send_pid_internal: failed to get chainlock.\n"));
224 tdb_append(tdb
, kbuf
, dbuf
);
225 tdb_chainunlock(tdb
, kbuf
);
227 SAFE_FREE(dbuf
.dptr
);
228 errno
= 0; /* paranoia */
229 return message_notify(pid
);
232 /* lock the record for the destination */
234 if (tdb_chainlock_with_timeout(tdb
, kbuf
, timeout
) == -1) {
235 DEBUG(0,("message_send_pid_internal: failed to get chainlock with timeout %ul.\n", timeout
));
239 if (tdb_chainlock(tdb
, kbuf
) == -1) {
240 DEBUG(0,("message_send_pid_internal: failed to get chainlock.\n"));
245 old_dbuf
= tdb_fetch(tdb
, kbuf
);
247 if (!old_dbuf
.dptr
) {
248 /* its a new record */
250 tdb_store(tdb
, kbuf
, dbuf
, TDB_REPLACE
);
251 tdb_chainunlock(tdb
, kbuf
);
253 SAFE_FREE(dbuf
.dptr
);
254 errno
= 0; /* paranoia */
255 return message_notify(pid
);
258 /* Not a new record. Check for duplicates. */
260 for(ptr
= (char *)old_dbuf
.dptr
; ptr
< old_dbuf
.dptr
+ old_dbuf
.dsize
; ) {
262 * First check if the message header matches, then, if it's a non-zero
263 * sized message, check if the data matches. If so it's a duplicate and
264 * we can discard it. JRA.
267 if (!memcmp(ptr
, &rec
, sizeof(rec
))) {
268 if (!len
|| (len
&& !memcmp( ptr
+ sizeof(rec
), buf
, len
))) {
269 tdb_chainunlock(tdb
, kbuf
);
270 DEBUG(10,("message_send_pid_internal: discarding duplicate message.\n"));
271 SAFE_FREE(dbuf
.dptr
);
272 SAFE_FREE(old_dbuf
.dptr
);
276 memcpy(&prec
, ptr
, sizeof(prec
));
277 ptr
+= sizeof(rec
) + prec
.len
;
280 /* we're adding to an existing entry */
282 tdb_append(tdb
, kbuf
, dbuf
);
283 tdb_chainunlock(tdb
, kbuf
);
285 SAFE_FREE(old_dbuf
.dptr
);
286 SAFE_FREE(dbuf
.dptr
);
288 errno
= 0; /* paranoia */
289 return message_notify(pid
);
292 /****************************************************************************
293 Send a message to a particular pid - no timeout.
294 ****************************************************************************/
296 BOOL
message_send_pid(struct process_id pid
, int msg_type
, const void *buf
, size_t len
, BOOL duplicates_allowed
)
298 return message_send_pid_internal(pid
, msg_type
, buf
, len
, duplicates_allowed
, 0);
301 /****************************************************************************
302 Send a message to a particular pid, with timeout in seconds.
303 ****************************************************************************/
305 BOOL
message_send_pid_with_timeout(struct process_id pid
, int msg_type
, const void *buf
, size_t len
,
306 BOOL duplicates_allowed
, unsigned int timeout
)
308 return message_send_pid_internal(pid
, msg_type
, buf
, len
, duplicates_allowed
, timeout
);
311 /****************************************************************************
312 Count the messages pending for a particular pid. Expensive....
313 ****************************************************************************/
315 unsigned int messages_pending_for_pid(struct process_id pid
)
320 unsigned int message_count
= 0;
322 kbuf
= message_key_pid(pid
);
324 dbuf
= tdb_fetch(tdb
, kbuf
);
325 if (dbuf
.dptr
== NULL
|| dbuf
.dsize
== 0) {
326 SAFE_FREE(dbuf
.dptr
);
330 for (buf
= dbuf
.dptr
; dbuf
.dsize
> sizeof(struct message_rec
);) {
331 struct message_rec rec
;
332 memcpy(&rec
, buf
, sizeof(rec
));
333 buf
+= (sizeof(rec
) + rec
.len
);
334 dbuf
.dsize
-= (sizeof(rec
) + rec
.len
);
338 SAFE_FREE(dbuf
.dptr
);
339 return message_count
;
342 /****************************************************************************
343 Retrieve all messages for the current process.
344 ****************************************************************************/
346 static BOOL
retrieve_all_messages(char **msgs_buf
, size_t *total_len
)
352 ZERO_STRUCT(null_dbuf
);
357 kbuf
= message_key_pid(pid_to_procid(sys_getpid()));
359 if (tdb_chainlock(tdb
, kbuf
) == -1)
362 dbuf
= tdb_fetch(tdb
, kbuf
);
364 * Replace with an empty record to keep the allocated
367 tdb_store(tdb
, kbuf
, null_dbuf
, TDB_REPLACE
);
368 tdb_chainunlock(tdb
, kbuf
);
370 if (dbuf
.dptr
== NULL
|| dbuf
.dsize
== 0) {
371 SAFE_FREE(dbuf
.dptr
);
375 *msgs_buf
= dbuf
.dptr
;
376 *total_len
= dbuf
.dsize
;
381 /****************************************************************************
382 Parse out the next message for the current process.
383 ****************************************************************************/
385 static BOOL
message_recv(char *msgs_buf
, size_t total_len
, int *msg_type
,
386 struct process_id
*src
, char **buf
, size_t *len
)
388 struct message_rec rec
;
389 char *ret_buf
= *buf
;
394 if (total_len
- (ret_buf
- msgs_buf
) < sizeof(rec
))
397 memcpy(&rec
, ret_buf
, sizeof(rec
));
398 ret_buf
+= sizeof(rec
);
400 if (rec
.msg_version
!= MESSAGE_VERSION
) {
401 DEBUG(0,("message version %d received (expected %d)\n", rec
.msg_version
, MESSAGE_VERSION
));
406 if (total_len
- (ret_buf
- msgs_buf
) < rec
.len
)
411 *msg_type
= rec
.msg_type
;
418 /****************************************************************************
419 Receive and dispatch any messages pending for this process.
420 Notice that all dispatch handlers for a particular msg_type get called,
421 so you can register multiple handlers for a message.
422 *NOTE*: Dispatch functions must be able to cope with incoming
423 messages on an *odd* byte boundary.
424 ****************************************************************************/
426 void message_dispatch(void)
429 struct process_id src
;
432 size_t len
, total_len
;
433 struct dispatch_fns
*dfn
;
436 if (!received_signal
)
439 DEBUG(10,("message_dispatch: received_signal = %d\n", received_signal
));
443 if (!retrieve_all_messages(&msgs_buf
, &total_len
))
446 for (buf
= msgs_buf
; message_recv(msgs_buf
, total_len
, &msg_type
, &src
, &buf
, &len
); buf
+= len
) {
447 DEBUG(10,("message_dispatch: received msg_type=%d "
448 "src_pid=%u\n", msg_type
,
449 (unsigned int) procid_to_pid(&src
)));
451 for (dfn
= dispatch_fns
; dfn
; dfn
= dfn
->next
) {
452 if (dfn
->msg_type
== msg_type
) {
453 DEBUG(10,("message_dispatch: processing message of type %d.\n", msg_type
));
454 dfn
->fn(msg_type
, src
, len
? (void *)buf
: NULL
, len
);
459 DEBUG(5,("message_dispatch: warning: no handlers registed for "
460 "msg_type %d in pid %u\n",
461 msg_type
, (unsigned int)sys_getpid()));
467 /****************************************************************************
468 Register a dispatch function for a particular message type.
469 *NOTE*: Dispatch functions must be able to cope with incoming
470 messages on an *odd* byte boundary.
471 ****************************************************************************/
473 void message_register(int msg_type
,
474 void (*fn
)(int msg_type
, struct process_id pid
,
475 void *buf
, size_t len
))
477 struct dispatch_fns
*dfn
;
479 dfn
= SMB_MALLOC_P(struct dispatch_fns
);
485 dfn
->msg_type
= msg_type
;
488 DLIST_ADD(dispatch_fns
, dfn
);
492 DEBUG(0,("message_register: Not enough memory. malloc failed!\n"));
496 /****************************************************************************
497 De-register the function for a particular message type.
498 ****************************************************************************/
500 void message_deregister(int msg_type
)
502 struct dispatch_fns
*dfn
, *next
;
504 for (dfn
= dispatch_fns
; dfn
; dfn
= next
) {
506 if (dfn
->msg_type
== msg_type
) {
507 DLIST_REMOVE(dispatch_fns
, dfn
);
522 /****************************************************************************
523 Send one of the messages for the broadcast.
524 ****************************************************************************/
526 static int traverse_fn(TDB_CONTEXT
*the_tdb
, TDB_DATA kbuf
, TDB_DATA dbuf
, void *state
)
528 struct connections_data crec
;
529 struct msg_all
*msg_all
= (struct msg_all
*)state
;
531 if (dbuf
.dsize
!= sizeof(crec
))
534 memcpy(&crec
, dbuf
.dptr
, sizeof(crec
));
539 /* Don't send if the receiver hasn't registered an interest. */
541 if(!(crec
.bcast_msg_flags
& msg_all
->msg_flag
))
544 /* If the msg send fails because the pid was not found (i.e. smbd died),
545 * the msg has already been deleted from the messages.tdb.*/
547 if (!message_send_pid(crec
.pid
, msg_all
->msg_type
,
548 msg_all
->buf
, msg_all
->len
,
549 msg_all
->duplicates
)) {
551 /* If the pid was not found delete the entry from connections.tdb */
553 if (errno
== ESRCH
) {
554 DEBUG(2,("pid %s doesn't exist - deleting connections %d [%s]\n",
555 procid_str_static(&crec
.pid
),
556 crec
.cnum
, crec
.name
));
557 tdb_delete(the_tdb
, kbuf
);
565 * Send a message to all smbd processes.
567 * It isn't very efficient, but should be OK for the sorts of
568 * applications that use it. When we need efficient broadcast we can add
571 * @param n_sent Set to the number of messages sent. This should be
572 * equal to the number of processes, but be careful for races.
574 * @retval True for success.
576 BOOL
message_send_all(TDB_CONTEXT
*conn_tdb
, int msg_type
,
577 const void *buf
, size_t len
,
578 BOOL duplicates_allowed
,
581 struct msg_all msg_all
;
583 msg_all
.msg_type
= msg_type
;
585 msg_all
.msg_flag
= FLAG_MSG_GENERAL
;
586 else if (msg_type
> 1000 && msg_type
< 2000)
587 msg_all
.msg_flag
= FLAG_MSG_NMBD
;
588 else if (msg_type
> 2000 && msg_type
< 2100)
589 msg_all
.msg_flag
= FLAG_MSG_PRINT_NOTIFY
;
590 else if (msg_type
> 2100 && msg_type
< 3000)
591 msg_all
.msg_flag
= FLAG_MSG_PRINT_GENERAL
;
592 else if (msg_type
> 3000 && msg_type
< 4000)
593 msg_all
.msg_flag
= FLAG_MSG_SMBD
;
599 msg_all
.duplicates
= duplicates_allowed
;
602 tdb_traverse(conn_tdb
, traverse_fn
, &msg_all
);
604 *n_sent
= msg_all
.n_sent
;
609 * Block and unblock receiving of messages. Allows removal of race conditions
610 * when doing a fork and changing message disposition.
613 void message_block(void)
615 BlockSignals(True
, SIGUSR1
);
618 void message_unblock(void)
620 BlockSignals(False
, SIGUSR1
);