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,
74 /****************************************************************************
76 ****************************************************************************/
78 void gfree_messages(void)
80 struct dispatch_fns *dfn, *next;
82 /* delete the dispatch_fns list */
86 DLIST_REMOVE(dispatch_fns, dfn);
92 /****************************************************************************
93 Notifications come in as signals.
94 ****************************************************************************/
96 static void sig_usr1(void)
99 sys_select_signal(SIGUSR1);
102 /****************************************************************************
103 A useful function for testing the message system.
104 ****************************************************************************/
106 static void ping_message(int msg_type, struct process_id src,
107 void *buf, size_t len, void *private_data)
109 const char *msg = buf ? (const char *)buf : "none";
111 DEBUG(1,("INFO: Received PING message from PID %s [%s]\n",
112 procid_str_static(&src), msg));
113 message_send_pid(src, MSG_PONG, buf, len, True);
116 /****************************************************************************
117 Initialise the messaging functions.
118 ****************************************************************************/
120 BOOL message_init(void)
127 tdb = tdb_open_log(lock_path("messages.tdb"),
128 0, TDB_CLEAR_IF_FIRST|TDB_DEFAULT,
129 O_RDWR|O_CREAT,0600);
132 DEBUG(0,("ERROR: Failed to initialise messages database\n"));
136 /* Activate the per-hashchain freelist */
137 tdb_set_max_dead(tdb, 5);
139 CatchSignal(SIGUSR1, SIGNAL_CAST sig_usr1);
141 message_register(MSG_PING, ping_message, NULL);
143 /* Register some debugging related messages */
145 register_msg_pool_usage();
146 register_dmalloc_msgs();
151 /*******************************************************************
152 Form a static tdb key from a pid.
153 ******************************************************************/
155 static TDB_DATA message_key_pid(struct process_id pid)
160 slprintf(key, sizeof(key)-1, "PID/%s", procid_str_static(&pid));
162 kbuf.dptr = (uint8 *)key;
163 kbuf.dsize = strlen(key)+1;
167 /****************************************************************************
168 Notify a process that it has a message. If the process doesn't exist
169 then delete its record in the database.
170 ****************************************************************************/
172 static NTSTATUS message_notify(struct process_id procid)
174 pid_t pid = procid.pid;
176 uid_t euid = geteuid();
179 * Doing kill with a non-positive pid causes messages to be
180 * sent to places we don't want.
186 become_root_uid_only();
189 ret = kill(pid, SIGUSR1);
192 unbecome_root_uid_only();
196 if (errno == ESRCH) {
197 DEBUG(2,("pid %d doesn't exist - deleting messages record\n",
199 tdb_delete(tdb, message_key_pid(procid));
202 * INVALID_HANDLE is the closest I can think of -- vl
204 return NT_STATUS_INVALID_HANDLE;
207 DEBUG(2,("message to process %d failed - %s\n", (int)pid,
211 * No call to map_nt_error_from_unix -- don't want to link in
212 * errormap.o into lots of utils.
215 if (errno == EINVAL) return NT_STATUS_INVALID_PARAMETER;
216 if (errno == EPERM) return NT_STATUS_ACCESS_DENIED;
217 return NT_STATUS_UNSUCCESSFUL;
223 /****************************************************************************
224 Send a message to a particular pid.
225 ****************************************************************************/
227 static NTSTATUS message_send_pid_internal(struct process_id pid, int msg_type,
228 const void *buf, size_t len,
229 BOOL duplicates_allowed,
230 unsigned int timeout)
235 struct message_rec rec;
237 struct message_rec prec;
239 /* NULL pointer means implicit length zero. */
241 SMB_ASSERT(len == 0);
245 * Doing kill with a non-positive pid causes messages to be
246 * sent to places we don't want.
249 SMB_ASSERT(procid_to_pid(&pid) > 0);
251 rec.msg_version = MESSAGE_VERSION;
252 rec.msg_type = msg_type;
254 rec.src = procid_self();
255 rec.len = buf ? len : 0;
257 kbuf = message_key_pid(pid);
259 dbuf.dptr = (uint8 *)SMB_MALLOC(len + sizeof(rec));
261 return NT_STATUS_NO_MEMORY;
264 memcpy(dbuf.dptr, &rec, sizeof(rec));
266 memcpy((void *)((char*)dbuf.dptr+sizeof(rec)), buf, len);
268 dbuf.dsize = len + sizeof(rec);
270 if (duplicates_allowed) {
272 /* If duplicates are allowed we can just append the message and return. */
274 /* lock the record for the destination */
276 if (tdb_chainlock_with_timeout(tdb, kbuf, timeout) == -1) {
277 DEBUG(0,("message_send_pid_internal: failed to get "
278 "chainlock with timeout %ul.\n", timeout));
279 return NT_STATUS_IO_TIMEOUT;
282 if (tdb_chainlock(tdb, kbuf) == -1) {
283 DEBUG(0,("message_send_pid_internal: failed to get "
285 return NT_STATUS_LOCK_NOT_GRANTED;
288 tdb_append(tdb, kbuf, dbuf);
289 tdb_chainunlock(tdb, kbuf);
291 SAFE_FREE(dbuf.dptr);
292 errno = 0; /* paranoia */
293 return message_notify(pid);
296 /* lock the record for the destination */
298 if (tdb_chainlock_with_timeout(tdb, kbuf, timeout) == -1) {
299 DEBUG(0,("message_send_pid_internal: failed to get chainlock "
300 "with timeout %ul.\n", timeout));
301 return NT_STATUS_IO_TIMEOUT;
304 if (tdb_chainlock(tdb, kbuf) == -1) {
305 DEBUG(0,("message_send_pid_internal: failed to get "
307 return NT_STATUS_LOCK_NOT_GRANTED;
311 old_dbuf = tdb_fetch(tdb, kbuf);
313 if (!old_dbuf.dptr) {
314 /* its a new record */
316 tdb_store(tdb, kbuf, dbuf, TDB_REPLACE);
317 tdb_chainunlock(tdb, kbuf);
319 SAFE_FREE(dbuf.dptr);
320 errno = 0; /* paranoia */
321 return message_notify(pid);
324 /* Not a new record. Check for duplicates. */
326 for(ptr = old_dbuf.dptr; ptr < old_dbuf.dptr + old_dbuf.dsize; ) {
328 * First check if the message header matches, then, if it's a non-zero
329 * sized message, check if the data matches. If so it's a duplicate and
330 * we can discard it. JRA.
333 if (!memcmp(ptr, &rec, sizeof(rec))) {
334 if (!len || (len && !memcmp( ptr + sizeof(rec), buf, len))) {
335 tdb_chainunlock(tdb, kbuf);
336 DEBUG(10,("message_send_pid_internal: discarding "
337 "duplicate message.\n"));
338 SAFE_FREE(dbuf.dptr);
339 SAFE_FREE(old_dbuf.dptr);
343 memcpy(&prec, ptr, sizeof(prec));
344 ptr += sizeof(rec) + prec.len;
347 /* we're adding to an existing entry */
349 tdb_append(tdb, kbuf, dbuf);
350 tdb_chainunlock(tdb, kbuf);
352 SAFE_FREE(old_dbuf.dptr);
353 SAFE_FREE(dbuf.dptr);
355 errno = 0; /* paranoia */
356 return message_notify(pid);
359 /****************************************************************************
360 Send a message to a particular pid - no timeout.
361 ****************************************************************************/
363 NTSTATUS message_send_pid(struct process_id pid, int msg_type, const void *buf,
364 size_t len, BOOL duplicates_allowed)
366 return message_send_pid_internal(pid, msg_type, buf, len,
367 duplicates_allowed, 0);
370 /****************************************************************************
371 Send a message to a particular pid, with timeout in seconds.
372 ****************************************************************************/
374 NTSTATUS message_send_pid_with_timeout(struct process_id pid, int msg_type,
375 const void *buf, size_t len,
376 BOOL duplicates_allowed, unsigned int timeout)
378 return message_send_pid_internal(pid, msg_type, buf, len, duplicates_allowed,
382 /****************************************************************************
383 Count the messages pending for a particular pid. Expensive....
384 ****************************************************************************/
386 unsigned int messages_pending_for_pid(struct process_id pid)
391 unsigned int message_count = 0;
393 kbuf = message_key_pid(pid);
395 dbuf = tdb_fetch(tdb, kbuf);
396 if (dbuf.dptr == NULL || dbuf.dsize == 0) {
397 SAFE_FREE(dbuf.dptr);
401 for (buf = dbuf.dptr; dbuf.dsize > sizeof(struct message_rec);) {
402 struct message_rec rec;
403 memcpy(&rec, buf, sizeof(rec));
404 buf += (sizeof(rec) + rec.len);
405 dbuf.dsize -= (sizeof(rec) + rec.len);
409 SAFE_FREE(dbuf.dptr);
410 return message_count;
413 /****************************************************************************
414 Retrieve all messages for the current process.
415 ****************************************************************************/
417 static BOOL retrieve_all_messages(char **msgs_buf, size_t *total_len)
423 ZERO_STRUCT(null_dbuf);
428 kbuf = message_key_pid(pid_to_procid(sys_getpid()));
430 if (tdb_chainlock(tdb, kbuf) == -1)
433 dbuf = tdb_fetch(tdb, kbuf);
435 * Replace with an empty record to keep the allocated
438 tdb_store(tdb, kbuf, null_dbuf, TDB_REPLACE);
439 tdb_chainunlock(tdb, kbuf);
441 if (dbuf.dptr == NULL || dbuf.dsize == 0) {
442 SAFE_FREE(dbuf.dptr);
446 *msgs_buf = (char *)dbuf.dptr;
447 *total_len = dbuf.dsize;
452 /****************************************************************************
453 Parse out the next message for the current process.
454 ****************************************************************************/
456 static BOOL message_recv(char *msgs_buf, size_t total_len, int *msg_type,
457 struct process_id *src, char **buf, size_t *len)
459 struct message_rec rec;
460 char *ret_buf = *buf;
465 if (total_len - (ret_buf - msgs_buf) < sizeof(rec))
468 memcpy(&rec, ret_buf, sizeof(rec));
469 ret_buf += sizeof(rec);
471 if (rec.msg_version != MESSAGE_VERSION) {
472 DEBUG(0,("message version %d received (expected %d)\n", rec.msg_version, MESSAGE_VERSION));
477 if (total_len - (ret_buf - msgs_buf) < rec.len)
482 *msg_type = rec.msg_type;
489 /****************************************************************************
490 Receive and dispatch any messages pending for this process.
491 JRA changed Dec 13 2006. Only one message handler now permitted per type.
492 *NOTE*: Dispatch functions must be able to cope with incoming
493 messages on an *odd* byte boundary.
494 ****************************************************************************/
496 void message_dispatch(void)
499 struct process_id src;
502 size_t len, total_len;
505 if (!received_signal)
508 DEBUG(10,("message_dispatch: received_signal = %d\n", received_signal));
512 if (!retrieve_all_messages(&msgs_buf, &total_len))
515 for (buf = msgs_buf; message_recv(msgs_buf, total_len, &msg_type, &src, &buf, &len); buf += len) {
516 struct dispatch_fns *dfn;
518 DEBUG(10,("message_dispatch: received msg_type=%d "
519 "src_pid=%u\n", msg_type,
520 (unsigned int) procid_to_pid(&src)));
523 for (dfn = dispatch_fns; dfn; dfn = dfn->next) {
524 if (dfn->msg_type == msg_type) {
525 DEBUG(10,("message_dispatch: processing message of type %d.\n", msg_type));
526 dfn->fn(msg_type, src,
527 len ? (void *)buf : NULL, len,
534 DEBUG(5,("message_dispatch: warning: no handler registed for "
535 "msg_type %d in pid %u\n",
536 msg_type, (unsigned int)sys_getpid()));
542 /****************************************************************************
543 Register/replace a dispatch function for a particular message type.
544 JRA changed Dec 13 2006. Only one message handler now permitted per type.
545 *NOTE*: Dispatch functions must be able to cope with incoming
546 messages on an *odd* byte boundary.
547 ****************************************************************************/
549 void message_register(int msg_type,
550 void (*fn)(int msg_type, struct process_id pid,
551 void *buf, size_t len,
555 struct dispatch_fns *dfn;
557 for (dfn = dispatch_fns; dfn; dfn = dfn->next) {
558 if (dfn->msg_type == msg_type) {
564 dfn = SMB_MALLOC_P(struct dispatch_fns);
570 dfn->msg_type = msg_type;
572 dfn->private_data = private_data;
574 DLIST_ADD(dispatch_fns, dfn);
578 DEBUG(0,("message_register: Not enough memory. malloc failed!\n"));
582 /****************************************************************************
583 De-register the function for a particular message type.
584 ****************************************************************************/
586 void message_deregister(int msg_type)
588 struct dispatch_fns *dfn, *next;
590 for (dfn = dispatch_fns; dfn; dfn = next) {
592 if (dfn->msg_type == msg_type) {
593 DLIST_REMOVE(dispatch_fns, dfn);
609 /****************************************************************************
610 Send one of the messages for the broadcast.
611 ****************************************************************************/
613 static int traverse_fn(TDB_CONTEXT *the_tdb, TDB_DATA kbuf, TDB_DATA dbuf, void *state)
615 struct connections_data crec;
616 struct msg_all *msg_all = (struct msg_all *)state;
619 if (dbuf.dsize != sizeof(crec))
622 memcpy(&crec, dbuf.dptr, sizeof(crec));
627 /* Don't send if the receiver hasn't registered an interest. */
629 if(!(crec.bcast_msg_flags & msg_all->msg_flag))
632 /* If the msg send fails because the pid was not found (i.e. smbd died),
633 * the msg has already been deleted from the messages.tdb.*/
635 status = message_send_pid(crec.pid, msg_all->msg_type,
636 msg_all->buf, msg_all->len,
637 msg_all->duplicates);
639 if (NT_STATUS_EQUAL(status, NT_STATUS_INVALID_HANDLE)) {
641 /* If the pid was not found delete the entry from connections.tdb */
643 DEBUG(2,("pid %s doesn't exist - deleting connections %d [%s]\n",
644 procid_str_static(&crec.pid), crec.cnum, crec.name));
645 tdb_delete(the_tdb, kbuf);
652 * Send a message to all smbd processes.
654 * It isn't very efficient, but should be OK for the sorts of
655 * applications that use it. When we need efficient broadcast we can add
658 * @param n_sent Set to the number of messages sent. This should be
659 * equal to the number of processes, but be careful for races.
661 * @retval True for success.
663 BOOL message_send_all(TDB_CONTEXT *conn_tdb, int msg_type,
664 const void *buf, size_t len,
665 BOOL duplicates_allowed,
668 struct msg_all msg_all;
670 msg_all.msg_type = msg_type;
672 msg_all.msg_flag = FLAG_MSG_GENERAL;
673 else if (msg_type > 1000 && msg_type < 2000)
674 msg_all.msg_flag = FLAG_MSG_NMBD;
675 else if (msg_type > 2000 && msg_type < 2100)
676 msg_all.msg_flag = FLAG_MSG_PRINT_NOTIFY;
677 else if (msg_type > 2100 && msg_type < 3000)
678 msg_all.msg_flag = FLAG_MSG_PRINT_GENERAL;
679 else if (msg_type > 3000 && msg_type < 4000)
680 msg_all.msg_flag = FLAG_MSG_SMBD;
686 msg_all.duplicates = duplicates_allowed;
689 tdb_traverse(conn_tdb, traverse_fn, &msg_all);
691 *n_sent = msg_all.n_sent;
696 * Block and unblock receiving of messages. Allows removal of race conditions
697 * when doing a fork and changing message disposition.
700 void message_block(void)
702 BlockSignals(True, SIGUSR1);
705 void message_unblock(void)
707 BlockSignals(False, SIGUSR1);
711 * Samba4 API wrapper around the Samba3 implementation. Yes, I know, we could
712 * import the whole Samba4 thing, but I want notify.c from Samba4 in first.
715 struct messaging_callback {
716 struct messaging_callback *prev, *next;
718 void (*fn)(struct messaging_context *msg, void *private_data,
720 struct server_id server_id, DATA_BLOB *data);
724 struct messaging_context {
726 struct messaging_callback *callbacks;
729 static int messaging_context_destructor(struct messaging_context *ctx)
731 struct messaging_callback *cb;
733 for (cb = ctx->callbacks; cb; cb = cb->next) {
735 * We unconditionally remove all instances of our callback
736 * from the tdb basis.
738 message_deregister(cb->msg_type);
743 struct messaging_context *messaging_init(TALLOC_CTX *mem_ctx,
744 struct server_id server_id,
745 struct event_context *ev)
747 struct messaging_context *ctx;
749 if (!(ctx = TALLOC_ZERO_P(mem_ctx, struct messaging_context))) {
754 talloc_set_destructor(ctx, messaging_context_destructor);
758 static void messaging_callback(int msg_type, struct process_id pid,
759 void *buf, size_t len, void *private_data)
761 struct messaging_context *ctx = talloc_get_type_abort(
762 private_data, struct messaging_context);
763 struct messaging_callback *cb, *next;
765 for (cb = ctx->callbacks; cb; cb = next) {
767 * Allow a callback to remove itself
771 if (msg_type == cb->msg_type) {
775 blob.data = (uint8 *)buf;
779 cb->fn(ctx, cb->private_data, msg_type, id, &blob);
785 * Register a dispatch function for a particular message type. Allow multiple
788 NTSTATUS messaging_register(struct messaging_context *ctx, void *private_data,
790 void (*fn)(struct messaging_context *msg,
793 struct server_id server_id,
796 struct messaging_callback *cb;
798 if (!(cb = talloc(ctx, struct messaging_callback))) {
799 return NT_STATUS_NO_MEMORY;
802 cb->msg_type = msg_type;
804 cb->private_data = private_data;
806 DLIST_ADD(ctx->callbacks, cb);
807 message_register(msg_type, messaging_callback, ctx);
812 De-register the function for a particular message type.
814 void messaging_deregister(struct messaging_context *ctx, uint32_t msg_type,
817 struct messaging_callback *cb, *next;
819 for (cb = ctx->callbacks; cb; cb = next) {
821 if ((cb->msg_type == msg_type)
822 && (cb->private_data == private_data)) {
823 DLIST_REMOVE(ctx->callbacks, cb);
830 Send a message to a particular server
832 NTSTATUS messaging_send(struct messaging_context *msg,
833 struct server_id server,
834 uint32_t msg_type, DATA_BLOB *data)
836 return message_send_pid_internal(server.id, msg_type, data->data,
837 data->length, True, 0);