2 Unix SMB/CIFS implementation.
3 Samba internal messaging functions
4 Copyright (C) 2007 by Volker Lendecke
6 This program is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2 of the License, or
9 (at your option) any later version.
11 This program is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with this program; if not, write to the Free Software
18 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
22 @defgroup messages Internal messaging framework
26 @brief Module for internal messaging between Samba daemons.
28 The idea is that if a part of Samba wants to do communication with
29 another Samba process then it will do a message_register() of a
30 dispatch function, and use message_send_pid() to send messages to
33 The dispatch function is given the pid of the sender, and it can
34 use that to reply by message_send_pid(). See ping_message() for a
37 @caution Dispatch functions must be able to cope with incoming
38 messages on an *odd* byte boundary.
40 This system doesn't have any inherent size limitations but is not
41 very efficient for large messages or when messages are sent in very
47 #include "librpc/gen_ndr/messaging.h"
48 #include "librpc/gen_ndr/ndr_messaging.h"
50 /* the locking database handle */
51 static int received_signal;
53 static NTSTATUS messaging_tdb_send(struct messaging_context *msg_ctx,
54 struct server_id pid, int msg_type,
55 const DATA_BLOB *data,
56 struct messaging_backend *backend);
58 /****************************************************************************
59 Notifications come in as signals.
60 ****************************************************************************/
62 static void sig_usr1(void)
65 sys_select_signal(SIGUSR1);
68 static int messaging_tdb_destructor(struct messaging_backend *tdb_ctx)
70 TDB_CONTEXT *tdb = (TDB_CONTEXT *)tdb_ctx->private_data;
75 /****************************************************************************
76 Initialise the messaging functions.
77 ****************************************************************************/
79 NTSTATUS messaging_tdb_init(struct messaging_context *msg_ctx,
81 struct messaging_backend **presult)
83 struct messaging_backend *result;
86 if (!(result = TALLOC_P(mem_ctx, struct messaging_backend))) {
87 DEBUG(0, ("talloc failed\n"));
88 return NT_STATUS_NO_MEMORY;
91 tdb = tdb_open_log(lock_path("messages.tdb"),
92 0, TDB_CLEAR_IF_FIRST|TDB_DEFAULT,
96 NTSTATUS status = map_nt_error_from_unix(errno);
97 DEBUG(0, ("ERROR: Failed to initialise messages database: "
98 "%s\n", strerror(errno)));
105 /* Activate the per-hashchain freelist */
106 tdb_set_max_dead(tdb, 5);
108 CatchSignal(SIGUSR1, SIGNAL_CAST sig_usr1);
110 result->private_data = (void *)tdb;
111 result->send_fn = messaging_tdb_send;
113 talloc_set_destructor(result, messaging_tdb_destructor);
119 /*******************************************************************
120 Form a static tdb key from a pid.
121 ******************************************************************/
123 static TDB_DATA message_key_pid(struct server_id pid)
128 slprintf(key, sizeof(key)-1, "PID/%s", procid_str_static(&pid));
130 kbuf.dptr = (uint8 *)key;
131 kbuf.dsize = strlen(key)+1;
136 Fetch the messaging array for a process
139 static NTSTATUS messaging_tdb_fetch(TDB_CONTEXT *msg_tdb,
142 struct messaging_array **presult)
144 struct messaging_array *result;
149 if (!(result = TALLOC_ZERO_P(mem_ctx, struct messaging_array))) {
150 return NT_STATUS_NO_MEMORY;
153 data = tdb_fetch(msg_tdb, key);
155 if (data.dptr == NULL) {
160 blob = data_blob_const(data.dptr, data.dsize);
162 status = ndr_pull_struct_blob(
163 &blob, result, result,
164 (ndr_pull_flags_fn_t)ndr_pull_messaging_array);
166 SAFE_FREE(data.dptr);
168 if (!NT_STATUS_IS_OK(status)) {
173 if (DEBUGLEVEL >= 10) {
174 DEBUG(10, ("messaging_tdb_fetch:\n"));
175 NDR_PRINT_DEBUG(messaging_array, result);
183 Store a messaging array for a pid
186 static NTSTATUS messaging_tdb_store(TDB_CONTEXT *msg_tdb,
188 struct messaging_array *array)
196 if (array->num_messages == 0) {
197 tdb_delete(msg_tdb, key);
201 if (!(mem_ctx = talloc_new(array))) {
202 return NT_STATUS_NO_MEMORY;
205 status = ndr_push_struct_blob(
206 &blob, mem_ctx, array,
207 (ndr_push_flags_fn_t)ndr_push_messaging_array);
209 if (!NT_STATUS_IS_OK(status)) {
210 talloc_free(mem_ctx);
214 if (DEBUGLEVEL >= 10) {
215 DEBUG(10, ("messaging_tdb_store:\n"));
216 NDR_PRINT_DEBUG(messaging_array, array);
219 data.dptr = blob.data;
220 data.dsize = blob.length;
222 ret = tdb_store(msg_tdb, key, data, TDB_REPLACE);
223 TALLOC_FREE(mem_ctx);
225 return (ret == 0) ? NT_STATUS_OK : NT_STATUS_INTERNAL_DB_CORRUPTION;
228 /****************************************************************************
229 Notify a process that it has a message. If the process doesn't exist
230 then delete its record in the database.
231 ****************************************************************************/
233 static NTSTATUS message_notify(struct server_id procid)
235 pid_t pid = procid.pid;
237 uid_t euid = geteuid();
240 * Doing kill with a non-positive pid causes messages to be
241 * sent to places we don't want.
247 /* If we're not root become so to send the message. */
249 set_effective_uid(0);
252 ret = kill(pid, SIGUSR1);
255 /* Go back to who we were. */
256 int saved_errno = errno;
257 restore_re_uid_fromroot();
266 * Something has gone wrong
269 DEBUG(2,("message to process %d failed - %s\n", (int)pid,
273 * No call to map_nt_error_from_unix -- don't want to link in
274 * errormap.o into lots of utils.
277 if (errno == ESRCH) return NT_STATUS_INVALID_HANDLE;
278 if (errno == EINVAL) return NT_STATUS_INVALID_PARAMETER;
279 if (errno == EPERM) return NT_STATUS_ACCESS_DENIED;
280 return NT_STATUS_UNSUCCESSFUL;
283 /****************************************************************************
284 Send a message to a particular pid.
285 ****************************************************************************/
287 static NTSTATUS messaging_tdb_send(struct messaging_context *msg_ctx,
288 struct server_id pid, int msg_type,
289 const DATA_BLOB *data,
290 struct messaging_backend *backend)
292 struct messaging_array *msg_array;
293 struct messaging_rec *rec;
296 TDB_DATA key = message_key_pid(pid);
297 TDB_CONTEXT *tdb = (TDB_CONTEXT *)backend->private_data;
299 /* NULL pointer means implicit length zero. */
301 SMB_ASSERT(data->length == 0);
305 * Doing kill with a non-positive pid causes messages to be
306 * sent to places we don't want.
309 SMB_ASSERT(procid_to_pid(&pid) > 0);
311 if (!(mem_ctx = talloc_init("message_send_pid"))) {
312 return NT_STATUS_NO_MEMORY;
315 if (tdb_chainlock(tdb, key) == -1) {
316 TALLOC_FREE(mem_ctx);
317 return NT_STATUS_LOCK_NOT_GRANTED;
320 status = messaging_tdb_fetch(tdb, key, mem_ctx, &msg_array);
322 if (!NT_STATUS_IS_OK(status)) {
326 if ((msg_type & MSG_FLAG_LOWPRIORITY)
327 && (msg_array->num_messages > 1000)) {
328 DEBUG(5, ("Dropping message for PID %s\n",
329 procid_str_static(&pid)));
330 status = NT_STATUS_INSUFFICIENT_RESOURCES;
334 if (!(rec = TALLOC_REALLOC_ARRAY(mem_ctx, msg_array->messages,
335 struct messaging_rec,
336 msg_array->num_messages+1))) {
337 status = NT_STATUS_NO_MEMORY;
341 rec[msg_array->num_messages].msg_version = MESSAGE_VERSION;
342 rec[msg_array->num_messages].msg_type = msg_type & MSG_TYPE_MASK;
343 rec[msg_array->num_messages].dest = pid;
344 rec[msg_array->num_messages].src = procid_self();
345 rec[msg_array->num_messages].buf = *data;
347 msg_array->messages = rec;
348 msg_array->num_messages += 1;
350 status = messaging_tdb_store(tdb, key, msg_array);
352 if (!NT_STATUS_IS_OK(status)) {
356 status = message_notify(pid);
358 if (NT_STATUS_EQUAL(status, NT_STATUS_INVALID_HANDLE)) {
359 DEBUG(2, ("pid %s doesn't exist - deleting messages record\n",
360 procid_str_static(&pid)));
361 tdb_delete(tdb, message_key_pid(pid));
365 tdb_chainunlock(tdb, key);
366 TALLOC_FREE(mem_ctx);
370 /****************************************************************************
371 Retrieve all messages for the current process.
372 ****************************************************************************/
374 static NTSTATUS retrieve_all_messages(TDB_CONTEXT *msg_tdb,
376 struct messaging_array **presult)
378 struct messaging_array *result;
379 TDB_DATA key = message_key_pid(procid_self());
382 if (tdb_chainlock(msg_tdb, key) == -1) {
383 return NT_STATUS_LOCK_NOT_GRANTED;
386 status = messaging_tdb_fetch(msg_tdb, key, mem_ctx, &result);
389 * We delete the record here, tdb_set_max_dead keeps it around
391 tdb_delete(msg_tdb, key);
392 tdb_chainunlock(msg_tdb, key);
394 if (NT_STATUS_IS_OK(status)) {
401 /****************************************************************************
402 Receive and dispatch any messages pending for this process.
403 JRA changed Dec 13 2006. Only one message handler now permitted per type.
404 *NOTE*: Dispatch functions must be able to cope with incoming
405 messages on an *odd* byte boundary.
406 ****************************************************************************/
408 void message_dispatch(struct messaging_context *msg_ctx)
410 struct messaging_array *msg_array = NULL;
411 TDB_CONTEXT *tdb = (TDB_CONTEXT *)(msg_ctx->local->private_data);
414 if (!received_signal)
417 DEBUG(10, ("message_dispatch: received_signal = %d\n",
422 if (!NT_STATUS_IS_OK(retrieve_all_messages(tdb, NULL, &msg_array))) {
426 for (i=0; i<msg_array->num_messages; i++) {
427 messaging_dispatch_rec(msg_ctx, &msg_array->messages[i]);
430 TALLOC_FREE(msg_array);