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, see <http://www.gnu.org/licenses/>.
21 @defgroup messages Internal messaging framework
25 @brief Module for internal messaging between Samba daemons.
27 The idea is that if a part of Samba wants to do communication with
28 another Samba process then it will do a message_register() of a
29 dispatch function, and use message_send_pid() to send messages to
32 The dispatch function is given the pid of the sender, and it can
33 use that to reply by message_send_pid(). See ping_message() for a
36 @caution Dispatch functions must be able to cope with incoming
37 messages on an *odd* byte boundary.
39 This system doesn't have any inherent size limitations but is not
40 very efficient for large messages or when messages are sent in very
46 #include "librpc/gen_ndr/messaging.h"
47 #include "librpc/gen_ndr/ndr_messaging.h"
49 static sig_atomic_t received_signal;
51 static NTSTATUS messaging_tdb_send(struct messaging_context *msg_ctx,
52 struct server_id pid, int msg_type,
53 const DATA_BLOB *data,
54 struct messaging_backend *backend);
56 /****************************************************************************
57 Notifications come in as signals.
58 ****************************************************************************/
60 static void sig_usr1(void)
63 sys_select_signal(SIGUSR1);
66 static int messaging_tdb_destructor(struct messaging_backend *tdb_ctx)
68 struct tdb_wrap *tdb = (struct tdb_wrap *)tdb_ctx->private_data;
73 /****************************************************************************
74 Initialise the messaging functions.
75 ****************************************************************************/
77 NTSTATUS messaging_tdb_init(struct messaging_context *msg_ctx,
79 struct messaging_backend **presult)
81 struct messaging_backend *result;
84 if (!(result = TALLOC_P(mem_ctx, struct messaging_backend))) {
85 DEBUG(0, ("talloc failed\n"));
86 return NT_STATUS_NO_MEMORY;
89 tdb = tdb_wrap_open(result, lock_path("messages.tdb"),
90 0, TDB_CLEAR_IF_FIRST|TDB_DEFAULT,
94 NTSTATUS status = map_nt_error_from_unix(errno);
95 DEBUG(0, ("ERROR: Failed to initialise messages database: "
96 "%s\n", strerror(errno)));
103 /* Activate the per-hashchain freelist */
104 tdb_set_max_dead(tdb->tdb, 5);
106 CatchSignal(SIGUSR1, SIGNAL_CAST sig_usr1);
108 result->private_data = (void *)tdb;
109 result->send_fn = messaging_tdb_send;
111 talloc_set_destructor(result, messaging_tdb_destructor);
117 /*******************************************************************
118 Form a static tdb key from a pid.
119 ******************************************************************/
121 static TDB_DATA message_key_pid(TALLOC_CTX *mem_ctx, struct server_id pid)
126 key = talloc_asprintf(talloc_tos(), "PID/%s", procid_str_static(&pid));
128 SMB_ASSERT(key != NULL);
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;
147 enum ndr_err_code ndr_err;
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 ndr_err = ndr_pull_struct_blob(
163 &blob, result, NULL, result,
164 (ndr_pull_flags_fn_t)ndr_pull_messaging_array);
166 SAFE_FREE(data.dptr);
168 if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
170 return ndr_map_error2ntstatus(ndr_err);
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)
192 enum ndr_err_code ndr_err;
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 ndr_err = ndr_push_struct_blob(
206 &blob, mem_ctx, NULL, array,
207 (ndr_push_flags_fn_t)ndr_push_messaging_array);
209 if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
210 talloc_free(mem_ctx);
211 return ndr_map_error2ntstatus(ndr_err);
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 struct tdb_wrap *tdb = (struct tdb_wrap *)backend->private_data;
297 TALLOC_CTX *frame = talloc_stackframe();
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 key = message_key_pid(frame, pid);
313 if (tdb_chainlock(tdb->tdb, key) == -1) {
315 return NT_STATUS_LOCK_NOT_GRANTED;
318 status = messaging_tdb_fetch(tdb->tdb, key, talloc_tos(), &msg_array);
320 if (!NT_STATUS_IS_OK(status)) {
324 if ((msg_type & MSG_FLAG_LOWPRIORITY)
325 && (msg_array->num_messages > 1000)) {
326 DEBUG(5, ("Dropping message for PID %s\n",
327 procid_str_static(&pid)));
328 status = NT_STATUS_INSUFFICIENT_RESOURCES;
332 if (!(rec = TALLOC_REALLOC_ARRAY(talloc_tos(), msg_array->messages,
333 struct messaging_rec,
334 msg_array->num_messages+1))) {
335 status = NT_STATUS_NO_MEMORY;
339 rec[msg_array->num_messages].msg_version = MESSAGE_VERSION;
340 rec[msg_array->num_messages].msg_type = msg_type & MSG_TYPE_MASK;
341 rec[msg_array->num_messages].dest = pid;
342 rec[msg_array->num_messages].src = procid_self();
343 rec[msg_array->num_messages].buf = *data;
345 msg_array->messages = rec;
346 msg_array->num_messages += 1;
348 status = messaging_tdb_store(tdb->tdb, key, msg_array);
350 if (!NT_STATUS_IS_OK(status)) {
354 status = message_notify(pid);
356 if (NT_STATUS_EQUAL(status, NT_STATUS_INVALID_HANDLE)) {
357 DEBUG(2, ("pid %s doesn't exist - deleting messages record\n",
358 procid_str_static(&pid)));
359 tdb_delete(tdb->tdb, message_key_pid(talloc_tos(), pid));
363 tdb_chainunlock(tdb->tdb, key);
368 /****************************************************************************
369 Retrieve all messages for the current process.
370 ****************************************************************************/
372 static NTSTATUS retrieve_all_messages(TDB_CONTEXT *msg_tdb,
374 struct messaging_array **presult)
376 struct messaging_array *result;
377 TDB_DATA key = message_key_pid(mem_ctx, procid_self());
380 if (tdb_chainlock(msg_tdb, key) == -1) {
381 TALLOC_FREE(key.dptr);
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)) {
397 TALLOC_FREE(key.dptr);
402 /****************************************************************************
403 Receive and dispatch any messages pending for this process.
404 JRA changed Dec 13 2006. Only one message handler now permitted per type.
405 *NOTE*: Dispatch functions must be able to cope with incoming
406 messages on an *odd* byte boundary.
407 ****************************************************************************/
409 void message_dispatch(struct messaging_context *msg_ctx)
411 struct messaging_array *msg_array = NULL;
412 struct tdb_wrap *tdb = (struct tdb_wrap *)
413 (msg_ctx->local->private_data);
416 if (!received_signal)
419 DEBUG(10, ("message_dispatch: received_signal = %d\n",
424 if (!NT_STATUS_IS_OK(retrieve_all_messages(tdb->tdb, NULL,
429 for (i=0; i<msg_array->num_messages; i++) {
430 messaging_dispatch_rec(msg_ctx, &msg_array->messages[i]);
433 TALLOC_FREE(msg_array);