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 3 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 static int received_signal;
52 static NTSTATUS messaging_tdb_send(struct messaging_context *msg_ctx,
53 struct server_id pid, int msg_type,
54 const DATA_BLOB *data,
55 struct messaging_backend *backend);
57 /****************************************************************************
58 Notifications come in as signals.
59 ****************************************************************************/
61 static void sig_usr1(void)
64 sys_select_signal(SIGUSR1);
67 static int messaging_tdb_destructor(struct messaging_backend *tdb_ctx)
69 TDB_CONTEXT *tdb = (TDB_CONTEXT *)tdb_ctx->private_data;
74 /****************************************************************************
75 Initialise the messaging functions.
76 ****************************************************************************/
78 NTSTATUS messaging_tdb_init(struct messaging_context *msg_ctx,
80 struct messaging_backend **presult)
82 struct messaging_backend *result;
85 if (!(result = TALLOC_P(mem_ctx, struct messaging_backend))) {
86 DEBUG(0, ("talloc failed\n"));
87 return NT_STATUS_NO_MEMORY;
90 tdb = tdb_open_log(lock_path("messages.tdb"),
91 0, TDB_CLEAR_IF_FIRST|TDB_DEFAULT,
95 NTSTATUS status = map_nt_error_from_unix(errno);
96 DEBUG(0, ("ERROR: Failed to initialise messages database: "
97 "%s\n", strerror(errno)));
104 /* Activate the per-hashchain freelist */
105 tdb_set_max_dead(tdb, 5);
107 CatchSignal(SIGUSR1, SIGNAL_CAST sig_usr1);
109 result->private_data = (void *)tdb;
110 result->send_fn = messaging_tdb_send;
112 talloc_set_destructor(result, messaging_tdb_destructor);
118 /*******************************************************************
119 Form a static tdb key from a pid.
120 ******************************************************************/
122 static TDB_DATA message_key_pid(struct server_id pid)
127 slprintf(key, sizeof(key)-1, "PID/%s", procid_str_static(&pid));
129 kbuf.dptr = (uint8 *)key;
130 kbuf.dsize = strlen(key)+1;
135 Fetch the messaging array for a process
138 static NTSTATUS messaging_tdb_fetch(TDB_CONTEXT *msg_tdb,
141 struct messaging_array **presult)
143 struct messaging_array *result;
148 if (!(result = TALLOC_ZERO_P(mem_ctx, struct messaging_array))) {
149 return NT_STATUS_NO_MEMORY;
152 data = tdb_fetch(msg_tdb, key);
154 if (data.dptr == NULL) {
159 blob = data_blob_const(data.dptr, data.dsize);
161 status = ndr_pull_struct_blob(
162 &blob, result, result,
163 (ndr_pull_flags_fn_t)ndr_pull_messaging_array);
165 SAFE_FREE(data.dptr);
167 if (!NT_STATUS_IS_OK(status)) {
172 if (DEBUGLEVEL >= 10) {
173 DEBUG(10, ("messaging_tdb_fetch:\n"));
174 NDR_PRINT_DEBUG(messaging_array, result);
182 Store a messaging array for a pid
185 static NTSTATUS messaging_tdb_store(TDB_CONTEXT *msg_tdb,
187 struct messaging_array *array)
195 if (array->num_messages == 0) {
196 tdb_delete(msg_tdb, key);
200 if (!(mem_ctx = talloc_new(array))) {
201 return NT_STATUS_NO_MEMORY;
204 status = ndr_push_struct_blob(
205 &blob, mem_ctx, array,
206 (ndr_push_flags_fn_t)ndr_push_messaging_array);
208 if (!NT_STATUS_IS_OK(status)) {
209 talloc_free(mem_ctx);
213 if (DEBUGLEVEL >= 10) {
214 DEBUG(10, ("messaging_tdb_store:\n"));
215 NDR_PRINT_DEBUG(messaging_array, array);
218 data.dptr = blob.data;
219 data.dsize = blob.length;
221 ret = tdb_store(msg_tdb, key, data, TDB_REPLACE);
222 TALLOC_FREE(mem_ctx);
224 return (ret == 0) ? NT_STATUS_OK : NT_STATUS_INTERNAL_DB_CORRUPTION;
227 /****************************************************************************
228 Notify a process that it has a message. If the process doesn't exist
229 then delete its record in the database.
230 ****************************************************************************/
232 static NTSTATUS message_notify(struct server_id procid)
234 pid_t pid = procid.pid;
236 uid_t euid = geteuid();
239 * Doing kill with a non-positive pid causes messages to be
240 * sent to places we don't want.
246 /* If we're not root become so to send the message. */
248 set_effective_uid(0);
251 ret = kill(pid, SIGUSR1);
254 /* Go back to who we were. */
255 int saved_errno = errno;
256 restore_re_uid_fromroot();
265 * Something has gone wrong
268 DEBUG(2,("message to process %d failed - %s\n", (int)pid,
272 * No call to map_nt_error_from_unix -- don't want to link in
273 * errormap.o into lots of utils.
276 if (errno == ESRCH) return NT_STATUS_INVALID_HANDLE;
277 if (errno == EINVAL) return NT_STATUS_INVALID_PARAMETER;
278 if (errno == EPERM) return NT_STATUS_ACCESS_DENIED;
279 return NT_STATUS_UNSUCCESSFUL;
282 /****************************************************************************
283 Send a message to a particular pid.
284 ****************************************************************************/
286 static NTSTATUS messaging_tdb_send(struct messaging_context *msg_ctx,
287 struct server_id pid, int msg_type,
288 const DATA_BLOB *data,
289 struct messaging_backend *backend)
291 struct messaging_array *msg_array;
292 struct messaging_rec *rec;
295 TDB_DATA key = message_key_pid(pid);
296 TDB_CONTEXT *tdb = (TDB_CONTEXT *)backend->private_data;
298 /* NULL pointer means implicit length zero. */
300 SMB_ASSERT(data->length == 0);
304 * Doing kill with a non-positive pid causes messages to be
305 * sent to places we don't want.
308 SMB_ASSERT(procid_to_pid(&pid) > 0);
310 if (!(mem_ctx = talloc_init("message_send_pid"))) {
311 return NT_STATUS_NO_MEMORY;
314 if (tdb_chainlock(tdb, key) == -1) {
315 TALLOC_FREE(mem_ctx);
316 return NT_STATUS_LOCK_NOT_GRANTED;
319 status = messaging_tdb_fetch(tdb, key, mem_ctx, &msg_array);
321 if (!NT_STATUS_IS_OK(status)) {
325 if ((msg_type & MSG_FLAG_LOWPRIORITY)
326 && (msg_array->num_messages > 1000)) {
327 DEBUG(5, ("Dropping message for PID %s\n",
328 procid_str_static(&pid)));
329 status = NT_STATUS_INSUFFICIENT_RESOURCES;
333 if (!(rec = TALLOC_REALLOC_ARRAY(mem_ctx, msg_array->messages,
334 struct messaging_rec,
335 msg_array->num_messages+1))) {
336 status = NT_STATUS_NO_MEMORY;
340 rec[msg_array->num_messages].msg_version = MESSAGE_VERSION;
341 rec[msg_array->num_messages].msg_type = msg_type & MSG_TYPE_MASK;
342 rec[msg_array->num_messages].dest = pid;
343 rec[msg_array->num_messages].src = procid_self();
344 rec[msg_array->num_messages].buf = *data;
346 msg_array->messages = rec;
347 msg_array->num_messages += 1;
349 status = messaging_tdb_store(tdb, key, msg_array);
351 if (!NT_STATUS_IS_OK(status)) {
355 status = message_notify(pid);
357 if (NT_STATUS_EQUAL(status, NT_STATUS_INVALID_HANDLE)) {
358 DEBUG(2, ("pid %s doesn't exist - deleting messages record\n",
359 procid_str_static(&pid)));
360 tdb_delete(tdb, message_key_pid(pid));
364 tdb_chainunlock(tdb, key);
365 TALLOC_FREE(mem_ctx);
369 /****************************************************************************
370 Retrieve all messages for the current process.
371 ****************************************************************************/
373 static NTSTATUS retrieve_all_messages(TDB_CONTEXT *msg_tdb,
375 struct messaging_array **presult)
377 struct messaging_array *result;
378 TDB_DATA key = message_key_pid(procid_self());
381 if (tdb_chainlock(msg_tdb, key) == -1) {
382 return NT_STATUS_LOCK_NOT_GRANTED;
385 status = messaging_tdb_fetch(msg_tdb, key, mem_ctx, &result);
388 * We delete the record here, tdb_set_max_dead keeps it around
390 tdb_delete(msg_tdb, key);
391 tdb_chainunlock(msg_tdb, key);
393 if (NT_STATUS_IS_OK(status)) {
400 /****************************************************************************
401 Receive and dispatch any messages pending for this process.
402 JRA changed Dec 13 2006. Only one message handler now permitted per type.
403 *NOTE*: Dispatch functions must be able to cope with incoming
404 messages on an *odd* byte boundary.
405 ****************************************************************************/
407 void message_dispatch(struct messaging_context *msg_ctx)
409 struct messaging_array *msg_array = NULL;
410 TDB_CONTEXT *tdb = (TDB_CONTEXT *)(msg_ctx->local->private_data);
413 if (!received_signal)
416 DEBUG(10, ("message_dispatch: received_signal = %d\n",
421 if (!NT_STATUS_IS_OK(retrieve_all_messages(tdb, NULL, &msg_array))) {
425 for (i=0; i<msg_array->num_messages; i++) {
426 messaging_dispatch_rec(msg_ctx, &msg_array->messages[i]);
429 TALLOC_FREE(msg_array);