2 Unix SMB/Netbios implementation.
4 Samba internal messaging functions
5 Copyright (C) Andrew Tridgell 2000
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.
22 /* this module is used for internal messaging between Samba daemons.
24 The idea is that if a part of Samba wants to do communication with
25 another Samba process then it will do a message_register() of a
26 dispatch function, and use message_send_pid() to send messages to
29 This system doesn't have any inherent size limitations but is not
30 very efficient for large messages or when messages are sent in very
37 /* the locking database handle */
38 static TDB_CONTEXT *tdb;
39 static int received_signal;
41 /* change the message version with any incompatible changes in the protocol */
42 #define MESSAGE_VERSION 1
52 /* we have a linked list of dispatch handlers */
53 static struct dispatch_fns {
54 struct dispatch_fns *next, *prev;
56 void (*fn)(int msg_type, pid_t pid, void *buf, size_t len);
59 /****************************************************************************
60 notifications come in as signals
61 ****************************************************************************/
62 static void sig_usr1(void)
68 /****************************************************************************
69 a useful function for testing the message system
70 ****************************************************************************/
71 void ping_message(int msg_type, pid_t src, void *buf, size_t len)
73 DEBUG(1,("INFO: Received PING message from PID %u\n",(unsigned int)src));
74 message_send_pid(src, MSG_PONG, buf, len, True);
76 /****************************************************************************
77 return current debug level
78 ****************************************************************************/
79 void debuglevel_message(int msg_type, pid_t src, void *buf, size_t len)
81 DEBUG(1,("INFO: Received REQ_DEBUGLEVEL message from PID %u\n",(unsigned int)src));
82 message_send_pid(src, MSG_DEBUGLEVEL, DEBUGLEVEL_CLASS, sizeof(DEBUGLEVEL_CLASS), True);
85 /****************************************************************************
86 Initialise the messaging functions.
87 ****************************************************************************/
88 BOOL message_init(void)
92 tdb = tdb_open_log(lock_path("messages.tdb"),
93 0, TDB_CLEAR_IF_FIRST|TDB_DEFAULT,
97 DEBUG(0,("ERROR: Failed to initialise messages database\n"));
101 CatchSignal(SIGUSR1, SIGNAL_CAST sig_usr1);
103 message_register(MSG_PING, ping_message);
104 message_register(MSG_REQ_DEBUGLEVEL, debuglevel_message);
110 /*******************************************************************
111 form a static tdb key from a pid
112 ******************************************************************/
113 static TDB_DATA message_key_pid(pid_t pid)
118 slprintf(key, sizeof(key)-1, "PID/%d", (int)pid);
120 kbuf.dptr = (char *)key;
121 kbuf.dsize = strlen(key)+1;
126 /****************************************************************************
127 notify a process that it has a message. If the process doesn't exist
128 then delete its record in the database
129 ****************************************************************************/
130 static BOOL message_notify(pid_t pid)
132 if (kill(pid, SIGUSR1) == -1) {
133 if (errno == ESRCH) {
134 DEBUG(2,("pid %d doesn't exist - deleting messages record\n", (int)pid));
135 tdb_delete(tdb, message_key_pid(pid));
137 DEBUG(2,("message to process %d failed - %s\n", (int)pid, strerror(errno)));
144 /****************************************************************************
145 send a message to a particular pid
146 ****************************************************************************/
147 BOOL message_send_pid(pid_t pid, int msg_type, void *buf, size_t len, BOOL duplicates_allowed)
151 struct message_rec rec;
154 rec.msg_version = MESSAGE_VERSION;
155 rec.msg_type = msg_type;
157 rec.src = sys_getpid();
160 kbuf = message_key_pid(pid);
162 /* lock the record for the destination */
163 tdb_chainlock(tdb, kbuf);
165 dbuf = tdb_fetch(tdb, kbuf);
168 /* its a new record */
169 p = (void *)malloc(len + sizeof(rec));
172 memcpy(p, &rec, sizeof(rec));
173 if (len > 0) memcpy((void *)((char*)p+sizeof(rec)), buf, len);
176 dbuf.dsize = len + sizeof(rec);
177 tdb_store(tdb, kbuf, dbuf, TDB_REPLACE);
182 if (!duplicates_allowed) {
184 struct message_rec prec;
186 for(ptr = (char *)dbuf.dptr; ptr < dbuf.dptr + dbuf.dsize; ) {
188 * First check if the message header matches, then, if it's a non-zero
189 * sized message, check if the data matches. If so it's a duplicate and
190 * we can discard it. JRA.
193 if (!memcmp(ptr, &rec, sizeof(rec))) {
194 if (!len || (len && !memcmp( ptr + sizeof(rec), (char *)buf, len))) {
195 DEBUG(10,("message_send_pid: discarding duplicate message.\n"));
196 SAFE_FREE(dbuf.dptr);
197 tdb_chainunlock(tdb, kbuf);
201 memcpy(&prec, ptr, sizeof(prec));
202 ptr += sizeof(rec) + prec.len;
206 /* we're adding to an existing entry */
207 p = (void *)malloc(dbuf.dsize + len + sizeof(rec));
210 memcpy(p, dbuf.dptr, dbuf.dsize);
211 memcpy((void *)((char*)p+dbuf.dsize), &rec, sizeof(rec));
212 if (len > 0) memcpy((void *)((char*)p+dbuf.dsize+sizeof(rec)), buf, len);
214 SAFE_FREE(dbuf.dptr);
216 dbuf.dsize += len + sizeof(rec);
217 tdb_store(tdb, kbuf, dbuf, TDB_REPLACE);
218 SAFE_FREE(dbuf.dptr);
221 tdb_chainunlock(tdb, kbuf);
222 errno = 0; /* paranoia */
223 return message_notify(pid);
226 tdb_chainunlock(tdb, kbuf);
227 errno = 0; /* paranoia */
233 /****************************************************************************
234 retrieve the next message for the current process
235 ****************************************************************************/
236 static BOOL message_recv(int *msg_type, pid_t *src, void **buf, size_t *len)
240 struct message_rec rec;
242 kbuf = message_key_pid(sys_getpid());
244 tdb_chainlock(tdb, kbuf);
246 dbuf = tdb_fetch(tdb, kbuf);
247 if (dbuf.dptr == NULL || dbuf.dsize == 0) goto failed;
249 memcpy(&rec, dbuf.dptr, sizeof(rec));
251 if (rec.msg_version != MESSAGE_VERSION) {
252 DEBUG(0,("message version %d received (expected %d)\n", rec.msg_version, MESSAGE_VERSION));
257 (*buf) = (void *)malloc(rec.len);
258 if (!(*buf)) goto failed;
260 memcpy(*buf, dbuf.dptr+sizeof(rec), rec.len);
266 *msg_type = rec.msg_type;
269 if (dbuf.dsize - (sizeof(rec)+rec.len) > 0)
270 memmove(dbuf.dptr, dbuf.dptr+sizeof(rec)+rec.len, dbuf.dsize - (sizeof(rec)+rec.len));
271 dbuf.dsize -= sizeof(rec)+rec.len;
274 tdb_delete(tdb, kbuf);
276 tdb_store(tdb, kbuf, dbuf, TDB_REPLACE);
278 SAFE_FREE(dbuf.dptr);
279 tdb_chainunlock(tdb, kbuf);
283 tdb_chainunlock(tdb, kbuf);
288 /****************************************************************************
289 receive and dispatch any messages pending for this process
290 notice that all dispatch handlers for a particular msg_type get called,
291 so you can register multiple handlers for a message
292 ****************************************************************************/
293 void message_dispatch(void)
299 struct dispatch_fns *dfn;
301 if (!received_signal)
304 DEBUG(10,("message_dispatch: received_signal = %d\n", received_signal));
307 while (message_recv(&msg_type, &src, &buf, &len)) {
308 for (dfn = dispatch_fns; dfn; dfn = dfn->next) {
309 if (dfn->msg_type == msg_type) {
310 DEBUG(10,("message_dispatch: processing message of type %d.\n", msg_type));
311 dfn->fn(msg_type, src, buf, len);
319 /****************************************************************************
320 register a dispatch function for a particular message type
321 ****************************************************************************/
322 void message_register(int msg_type,
323 void (*fn)(int msg_type, pid_t pid, void *buf, size_t len))
325 struct dispatch_fns *dfn;
327 dfn = (struct dispatch_fns *)malloc(sizeof(*dfn));
333 dfn->msg_type = msg_type;
336 DLIST_ADD(dispatch_fns, dfn);
340 DEBUG(0,("message_register: Not enough memory. malloc failed!\n"));
344 /****************************************************************************
345 de-register the function for a particular message type
346 ****************************************************************************/
347 void message_deregister(int msg_type)
349 struct dispatch_fns *dfn, *next;
351 for (dfn = dispatch_fns; dfn; dfn = next) {
353 if (dfn->msg_type == msg_type) {
354 DLIST_REMOVE(dispatch_fns, dfn);
367 /****************************************************************************
368 send one of the messages for the broadcast
369 ****************************************************************************/
370 static int traverse_fn(TDB_CONTEXT *the_tdb, TDB_DATA kbuf, TDB_DATA dbuf, void *state)
372 struct connections_data crec;
373 struct msg_all *msg_all = (struct msg_all *)state;
375 if (dbuf.dsize != sizeof(crec))
378 memcpy(&crec, dbuf.dptr, sizeof(crec));
383 /* if the msg send fails because the pid was not found (i.e. smbd died),
384 * the msg has already been deleted from the messages.tdb.*/
385 if (!message_send_pid(crec.pid, msg_all->msg_type, msg_all->buf, msg_all->len,
386 msg_all->duplicates)) {
388 /* if the pid was not found delete the entry from connections.tdb */
389 if (errno == ESRCH) {
390 DEBUG(2,("pid %u doesn't exist - deleting connections %d [%s]\n",
391 (unsigned int)crec.pid, crec.cnum, crec.name));
392 tdb_delete(the_tdb, kbuf);
398 /****************************************************************************
399 this is a useful function for sending messages to all smbd processes.
400 It isn't very efficient, but should be OK for the sorts of applications that
401 use it. When we need efficient broadcast we can add it.
402 ****************************************************************************/
403 BOOL message_send_all(TDB_CONTEXT *conn_tdb, int msg_type, void *buf, size_t len, BOOL duplicates_allowed)
405 struct msg_all msg_all;
407 msg_all.msg_type = msg_type;
410 msg_all.duplicates = duplicates_allowed;
412 tdb_traverse(conn_tdb, traverse_fn, &msg_all);