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 "system/filesys.h"
47 #include "librpc/gen_ndr/messaging.h"
48 #include "librpc/gen_ndr/ndr_messaging.h"
51 struct messaging_tdb_context {
52 struct messaging_context *msg_ctx;
54 struct tevent_signal *se;
55 int received_messages;
58 static NTSTATUS messaging_tdb_send(struct messaging_context *msg_ctx,
59 struct server_id pid, int msg_type,
60 const DATA_BLOB *data,
61 struct messaging_backend *backend);
62 static void message_dispatch(struct messaging_context *msg_ctx);
64 static void messaging_tdb_signal_handler(struct tevent_context *ev_ctx,
65 struct tevent_signal *se,
66 int signum, int count,
67 void *_info, void *private_data)
69 struct messaging_tdb_context *ctx = talloc_get_type(private_data,
70 struct messaging_tdb_context);
72 ctx->received_messages++;
74 DEBUG(10, ("messaging_tdb_signal_handler: sig[%d] count[%d] msgs[%d]\n",
75 signum, count, ctx->received_messages));
77 message_dispatch(ctx->msg_ctx);
80 /****************************************************************************
81 Initialise the messaging functions.
82 ****************************************************************************/
84 NTSTATUS messaging_tdb_init(struct messaging_context *msg_ctx,
86 struct messaging_backend **presult)
88 struct messaging_backend *result;
89 struct messaging_tdb_context *ctx;
91 if (!(result = TALLOC_P(mem_ctx, struct messaging_backend))) {
92 DEBUG(0, ("talloc failed\n"));
93 return NT_STATUS_NO_MEMORY;
96 ctx = TALLOC_ZERO_P(result, struct messaging_tdb_context);
98 DEBUG(0, ("talloc failed\n"));
100 return NT_STATUS_NO_MEMORY;
102 result->private_data = ctx;
103 result->send_fn = messaging_tdb_send;
105 ctx->msg_ctx = msg_ctx;
107 ctx->tdb = tdb_wrap_open(ctx, lock_path("messages.tdb"), 0,
108 TDB_CLEAR_IF_FIRST|TDB_DEFAULT|TDB_VOLATILE|TDB_INCOMPATIBLE_HASH,
109 O_RDWR|O_CREAT,0600);
112 NTSTATUS status = map_nt_error_from_unix(errno);
113 DEBUG(2, ("ERROR: Failed to initialise messages database: "
114 "%s\n", strerror(errno)));
119 ctx->se = tevent_add_signal(msg_ctx->event_ctx,
122 messaging_tdb_signal_handler,
125 NTSTATUS status = map_nt_error_from_unix(errno);
126 DEBUG(0, ("ERROR: Failed to initialise messages signal handler: "
127 "%s\n", strerror(errno)));
138 bool messaging_tdb_parent_init(TALLOC_CTX *mem_ctx)
143 * Open the tdb in the parent process (smbd) so that our
144 * CLEAR_IF_FIRST optimization in tdb_reopen_all can properly
148 db = tdb_wrap_open(mem_ctx, lock_path("messages.tdb"), 0,
149 TDB_CLEAR_IF_FIRST|TDB_DEFAULT|TDB_VOLATILE|TDB_INCOMPATIBLE_HASH,
150 O_RDWR|O_CREAT,0600);
152 DEBUG(1, ("could not open messaging.tdb: %s\n",
159 /*******************************************************************
160 Form a static tdb key from a pid.
161 ******************************************************************/
163 static TDB_DATA message_key_pid(TALLOC_CTX *mem_ctx, struct server_id pid)
168 key = talloc_asprintf(talloc_tos(), "PID/%s", procid_str_static(&pid));
170 SMB_ASSERT(key != NULL);
172 kbuf.dptr = (uint8 *)key;
173 kbuf.dsize = strlen(key)+1;
178 Fetch the messaging array for a process
181 static NTSTATUS messaging_tdb_fetch(TDB_CONTEXT *msg_tdb,
184 struct messaging_array **presult)
186 struct messaging_array *result;
189 enum ndr_err_code ndr_err;
191 if (!(result = TALLOC_ZERO_P(mem_ctx, struct messaging_array))) {
192 return NT_STATUS_NO_MEMORY;
195 data = tdb_fetch(msg_tdb, key);
197 if (data.dptr == NULL) {
202 blob = data_blob_const(data.dptr, data.dsize);
204 ndr_err = ndr_pull_struct_blob(
205 &blob, result, result,
206 (ndr_pull_flags_fn_t)ndr_pull_messaging_array);
208 SAFE_FREE(data.dptr);
210 if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
212 return ndr_map_error2ntstatus(ndr_err);
215 if (DEBUGLEVEL >= 10) {
216 DEBUG(10, ("messaging_tdb_fetch:\n"));
217 NDR_PRINT_DEBUG(messaging_array, result);
225 Store a messaging array for a pid
228 static NTSTATUS messaging_tdb_store(TDB_CONTEXT *msg_tdb,
230 struct messaging_array *array)
234 enum ndr_err_code ndr_err;
238 if (array->num_messages == 0) {
239 tdb_delete(msg_tdb, key);
243 if (!(mem_ctx = talloc_new(array))) {
244 return NT_STATUS_NO_MEMORY;
247 ndr_err = ndr_push_struct_blob(&blob, mem_ctx, array,
248 (ndr_push_flags_fn_t)ndr_push_messaging_array);
250 if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
251 talloc_free(mem_ctx);
252 return ndr_map_error2ntstatus(ndr_err);
255 if (DEBUGLEVEL >= 10) {
256 DEBUG(10, ("messaging_tdb_store:\n"));
257 NDR_PRINT_DEBUG(messaging_array, array);
260 data.dptr = blob.data;
261 data.dsize = blob.length;
263 ret = tdb_store(msg_tdb, key, data, TDB_REPLACE);
264 TALLOC_FREE(mem_ctx);
266 return (ret == 0) ? NT_STATUS_OK : NT_STATUS_INTERNAL_DB_CORRUPTION;
269 /****************************************************************************
270 Notify a process that it has a message. If the process doesn't exist
271 then delete its record in the database.
272 ****************************************************************************/
274 static NTSTATUS message_notify(struct server_id procid)
276 pid_t pid = procid.pid;
278 uid_t euid = geteuid();
281 * Doing kill with a non-positive pid causes messages to be
282 * sent to places we don't want.
288 /* If we're not root become so to send the message. */
290 set_effective_uid(0);
293 ret = kill(pid, SIGUSR1);
296 /* Go back to who we were. */
297 int saved_errno = errno;
298 restore_re_uid_fromroot();
307 * Something has gone wrong
310 DEBUG(2,("message to process %d failed - %s\n", (int)pid,
314 * No call to map_nt_error_from_unix -- don't want to link in
315 * errormap.o into lots of utils.
318 if (errno == ESRCH) return NT_STATUS_INVALID_HANDLE;
319 if (errno == EINVAL) return NT_STATUS_INVALID_PARAMETER;
320 if (errno == EPERM) return NT_STATUS_ACCESS_DENIED;
321 return NT_STATUS_UNSUCCESSFUL;
324 /****************************************************************************
325 Send a message to a particular pid.
326 ****************************************************************************/
328 static NTSTATUS messaging_tdb_send(struct messaging_context *msg_ctx,
329 struct server_id pid, int msg_type,
330 const DATA_BLOB *data,
331 struct messaging_backend *backend)
333 struct messaging_tdb_context *ctx = talloc_get_type(backend->private_data,
334 struct messaging_tdb_context);
335 struct messaging_array *msg_array;
336 struct messaging_rec *rec;
339 struct tdb_wrap *tdb = ctx->tdb;
340 TALLOC_CTX *frame = talloc_stackframe();
342 /* NULL pointer means implicit length zero. */
344 SMB_ASSERT(data->length == 0);
348 * Doing kill with a non-positive pid causes messages to be
349 * sent to places we don't want.
352 SMB_ASSERT(procid_to_pid(&pid) > 0);
354 key = message_key_pid(frame, pid);
356 if (tdb_chainlock(tdb->tdb, key) == -1) {
358 return NT_STATUS_LOCK_NOT_GRANTED;
361 status = messaging_tdb_fetch(tdb->tdb, key, talloc_tos(), &msg_array);
363 if (!NT_STATUS_IS_OK(status)) {
367 if ((msg_type & MSG_FLAG_LOWPRIORITY)
368 && (msg_array->num_messages > 1000)) {
369 DEBUG(5, ("Dropping message for PID %s\n",
370 procid_str_static(&pid)));
371 status = NT_STATUS_INSUFFICIENT_RESOURCES;
375 if (!(rec = TALLOC_REALLOC_ARRAY(talloc_tos(), msg_array->messages,
376 struct messaging_rec,
377 msg_array->num_messages+1))) {
378 status = NT_STATUS_NO_MEMORY;
382 rec[msg_array->num_messages].msg_version = MESSAGE_VERSION;
383 rec[msg_array->num_messages].msg_type = msg_type & MSG_TYPE_MASK;
384 rec[msg_array->num_messages].dest = pid;
385 rec[msg_array->num_messages].src = msg_ctx->id;
386 rec[msg_array->num_messages].buf = *data;
388 msg_array->messages = rec;
389 msg_array->num_messages += 1;
391 status = messaging_tdb_store(tdb->tdb, key, msg_array);
393 if (!NT_STATUS_IS_OK(status)) {
397 status = message_notify(pid);
399 if (NT_STATUS_EQUAL(status, NT_STATUS_INVALID_HANDLE)) {
400 DEBUG(2, ("pid %s doesn't exist - deleting messages record\n",
401 procid_str_static(&pid)));
402 tdb_delete(tdb->tdb, message_key_pid(talloc_tos(), pid));
406 tdb_chainunlock(tdb->tdb, key);
411 /****************************************************************************
412 Retrieve all messages for a process.
413 ****************************************************************************/
415 static NTSTATUS retrieve_all_messages(TDB_CONTEXT *msg_tdb,
418 struct messaging_array **presult)
420 struct messaging_array *result;
421 TDB_DATA key = message_key_pid(mem_ctx, id);
424 if (tdb_chainlock(msg_tdb, key) == -1) {
425 TALLOC_FREE(key.dptr);
426 return NT_STATUS_LOCK_NOT_GRANTED;
429 status = messaging_tdb_fetch(msg_tdb, key, mem_ctx, &result);
432 * We delete the record here, tdb_set_max_dead keeps it around
434 tdb_delete(msg_tdb, key);
435 tdb_chainunlock(msg_tdb, key);
437 if (NT_STATUS_IS_OK(status)) {
441 TALLOC_FREE(key.dptr);
446 /****************************************************************************
447 Receive and dispatch any messages pending for this process.
448 JRA changed Dec 13 2006. Only one message handler now permitted per type.
449 *NOTE*: Dispatch functions must be able to cope with incoming
450 messages on an *odd* byte boundary.
451 ****************************************************************************/
453 static void message_dispatch(struct messaging_context *msg_ctx)
455 struct messaging_tdb_context *ctx = talloc_get_type(msg_ctx->local->private_data,
456 struct messaging_tdb_context);
457 struct messaging_array *msg_array = NULL;
458 struct tdb_wrap *tdb = ctx->tdb;
462 if (ctx->received_messages == 0) {
466 DEBUG(10, ("message_dispatch: received_messages = %d\n",
467 ctx->received_messages));
469 status = retrieve_all_messages(tdb->tdb, msg_ctx->id, NULL, &msg_array);
470 if (!NT_STATUS_IS_OK(status)) {
471 DEBUG(0, ("message_dispatch: failed to retrieve messages: %s\n",
476 ctx->received_messages = 0;
478 for (i=0; i<msg_array->num_messages; i++) {
479 messaging_dispatch_rec(msg_ctx, &msg_array->messages[i]);
482 TALLOC_FREE(msg_array);