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 struct messaging_tdb_context {
50 struct messaging_context *msg_ctx;
52 struct tevent_signal *se;
53 int received_messages;
56 static NTSTATUS messaging_tdb_send(struct messaging_context *msg_ctx,
57 struct server_id pid, int msg_type,
58 const DATA_BLOB *data,
59 struct messaging_backend *backend);
60 static void message_dispatch(struct messaging_context *msg_ctx);
62 static void messaging_tdb_signal_handler(struct tevent_context *ev_ctx,
63 struct tevent_signal *se,
64 int signum, int count,
65 void *_info, void *private_data)
67 struct messaging_tdb_context *ctx = talloc_get_type(private_data,
68 struct messaging_tdb_context);
70 ctx->received_messages++;
72 DEBUG(10, ("messaging_tdb_signal_handler: sig[%d] count[%d] msgs[%d]\n",
73 signum, count, ctx->received_messages));
75 message_dispatch(ctx->msg_ctx);
78 /****************************************************************************
79 Initialise the messaging functions.
80 ****************************************************************************/
82 NTSTATUS messaging_tdb_init(struct messaging_context *msg_ctx,
84 struct messaging_backend **presult)
86 struct messaging_backend *result;
87 struct messaging_tdb_context *ctx;
89 if (!(result = TALLOC_P(mem_ctx, struct messaging_backend))) {
90 DEBUG(0, ("talloc failed\n"));
91 return NT_STATUS_NO_MEMORY;
94 ctx = TALLOC_ZERO_P(result, struct messaging_tdb_context);
96 DEBUG(0, ("talloc failed\n"));
98 return NT_STATUS_NO_MEMORY;
100 result->private_data = ctx;
101 result->send_fn = messaging_tdb_send;
103 ctx->msg_ctx = msg_ctx;
105 ctx->tdb = tdb_wrap_open(ctx, lock_path("messages.tdb"), 0,
106 TDB_CLEAR_IF_FIRST|TDB_DEFAULT|TDB_VOLATILE,
107 O_RDWR|O_CREAT,0600);
110 NTSTATUS status = map_nt_error_from_unix(errno);
111 DEBUG(0, ("ERROR: Failed to initialise messages database: "
112 "%s\n", strerror(errno)));
117 ctx->se = tevent_add_signal(msg_ctx->event_ctx,
120 messaging_tdb_signal_handler,
123 NTSTATUS status = map_nt_error_from_unix(errno);
124 DEBUG(0, ("ERROR: Failed to initialise messages signal handler: "
125 "%s\n", strerror(errno)));
136 /*******************************************************************
137 Form a static tdb key from a pid.
138 ******************************************************************/
140 static TDB_DATA message_key_pid(TALLOC_CTX *mem_ctx, struct server_id pid)
145 key = talloc_asprintf(talloc_tos(), "PID/%s", procid_str_static(&pid));
147 SMB_ASSERT(key != NULL);
149 kbuf.dptr = (uint8 *)key;
150 kbuf.dsize = strlen(key)+1;
155 Fetch the messaging array for a process
158 static NTSTATUS messaging_tdb_fetch(TDB_CONTEXT *msg_tdb,
161 struct messaging_array **presult)
163 struct messaging_array *result;
166 enum ndr_err_code ndr_err;
168 if (!(result = TALLOC_ZERO_P(mem_ctx, struct messaging_array))) {
169 return NT_STATUS_NO_MEMORY;
172 data = tdb_fetch(msg_tdb, key);
174 if (data.dptr == NULL) {
179 blob = data_blob_const(data.dptr, data.dsize);
181 ndr_err = ndr_pull_struct_blob(
182 &blob, result, NULL, result,
183 (ndr_pull_flags_fn_t)ndr_pull_messaging_array);
185 SAFE_FREE(data.dptr);
187 if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
189 return ndr_map_error2ntstatus(ndr_err);
192 if (DEBUGLEVEL >= 10) {
193 DEBUG(10, ("messaging_tdb_fetch:\n"));
194 NDR_PRINT_DEBUG(messaging_array, result);
202 Store a messaging array for a pid
205 static NTSTATUS messaging_tdb_store(TDB_CONTEXT *msg_tdb,
207 struct messaging_array *array)
211 enum ndr_err_code ndr_err;
215 if (array->num_messages == 0) {
216 tdb_delete(msg_tdb, key);
220 if (!(mem_ctx = talloc_new(array))) {
221 return NT_STATUS_NO_MEMORY;
224 ndr_err = ndr_push_struct_blob(
225 &blob, mem_ctx, NULL, array,
226 (ndr_push_flags_fn_t)ndr_push_messaging_array);
228 if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
229 talloc_free(mem_ctx);
230 return ndr_map_error2ntstatus(ndr_err);
233 if (DEBUGLEVEL >= 10) {
234 DEBUG(10, ("messaging_tdb_store:\n"));
235 NDR_PRINT_DEBUG(messaging_array, array);
238 data.dptr = blob.data;
239 data.dsize = blob.length;
241 ret = tdb_store(msg_tdb, key, data, TDB_REPLACE);
242 TALLOC_FREE(mem_ctx);
244 return (ret == 0) ? NT_STATUS_OK : NT_STATUS_INTERNAL_DB_CORRUPTION;
247 /****************************************************************************
248 Notify a process that it has a message. If the process doesn't exist
249 then delete its record in the database.
250 ****************************************************************************/
252 static NTSTATUS message_notify(struct server_id procid)
254 pid_t pid = procid.pid;
256 uid_t euid = geteuid();
259 * Doing kill with a non-positive pid causes messages to be
260 * sent to places we don't want.
266 /* If we're not root become so to send the message. */
268 set_effective_uid(0);
271 ret = kill(pid, SIGUSR1);
274 /* Go back to who we were. */
275 int saved_errno = errno;
276 restore_re_uid_fromroot();
285 * Something has gone wrong
288 DEBUG(2,("message to process %d failed - %s\n", (int)pid,
292 * No call to map_nt_error_from_unix -- don't want to link in
293 * errormap.o into lots of utils.
296 if (errno == ESRCH) return NT_STATUS_INVALID_HANDLE;
297 if (errno == EINVAL) return NT_STATUS_INVALID_PARAMETER;
298 if (errno == EPERM) return NT_STATUS_ACCESS_DENIED;
299 return NT_STATUS_UNSUCCESSFUL;
302 /****************************************************************************
303 Send a message to a particular pid.
304 ****************************************************************************/
306 static NTSTATUS messaging_tdb_send(struct messaging_context *msg_ctx,
307 struct server_id pid, int msg_type,
308 const DATA_BLOB *data,
309 struct messaging_backend *backend)
311 struct messaging_tdb_context *ctx = talloc_get_type(backend->private_data,
312 struct messaging_tdb_context);
313 struct messaging_array *msg_array;
314 struct messaging_rec *rec;
317 struct tdb_wrap *tdb = ctx->tdb;
318 TALLOC_CTX *frame = talloc_stackframe();
320 /* NULL pointer means implicit length zero. */
322 SMB_ASSERT(data->length == 0);
326 * Doing kill with a non-positive pid causes messages to be
327 * sent to places we don't want.
330 SMB_ASSERT(procid_to_pid(&pid) > 0);
332 key = message_key_pid(frame, pid);
334 if (tdb_chainlock(tdb->tdb, key) == -1) {
336 return NT_STATUS_LOCK_NOT_GRANTED;
339 status = messaging_tdb_fetch(tdb->tdb, key, talloc_tos(), &msg_array);
341 if (!NT_STATUS_IS_OK(status)) {
345 if ((msg_type & MSG_FLAG_LOWPRIORITY)
346 && (msg_array->num_messages > 1000)) {
347 DEBUG(5, ("Dropping message for PID %s\n",
348 procid_str_static(&pid)));
349 status = NT_STATUS_INSUFFICIENT_RESOURCES;
353 if (!(rec = TALLOC_REALLOC_ARRAY(talloc_tos(), msg_array->messages,
354 struct messaging_rec,
355 msg_array->num_messages+1))) {
356 status = NT_STATUS_NO_MEMORY;
360 rec[msg_array->num_messages].msg_version = MESSAGE_VERSION;
361 rec[msg_array->num_messages].msg_type = msg_type & MSG_TYPE_MASK;
362 rec[msg_array->num_messages].dest = pid;
363 rec[msg_array->num_messages].src = procid_self();
364 rec[msg_array->num_messages].buf = *data;
366 msg_array->messages = rec;
367 msg_array->num_messages += 1;
369 status = messaging_tdb_store(tdb->tdb, key, msg_array);
371 if (!NT_STATUS_IS_OK(status)) {
375 status = message_notify(pid);
377 if (NT_STATUS_EQUAL(status, NT_STATUS_INVALID_HANDLE)) {
378 DEBUG(2, ("pid %s doesn't exist - deleting messages record\n",
379 procid_str_static(&pid)));
380 tdb_delete(tdb->tdb, message_key_pid(talloc_tos(), pid));
384 tdb_chainunlock(tdb->tdb, key);
389 /****************************************************************************
390 Retrieve all messages for the current process.
391 ****************************************************************************/
393 static NTSTATUS retrieve_all_messages(TDB_CONTEXT *msg_tdb,
395 struct messaging_array **presult)
397 struct messaging_array *result;
398 TDB_DATA key = message_key_pid(mem_ctx, procid_self());
401 if (tdb_chainlock(msg_tdb, key) == -1) {
402 TALLOC_FREE(key.dptr);
403 return NT_STATUS_LOCK_NOT_GRANTED;
406 status = messaging_tdb_fetch(msg_tdb, key, mem_ctx, &result);
409 * We delete the record here, tdb_set_max_dead keeps it around
411 tdb_delete(msg_tdb, key);
412 tdb_chainunlock(msg_tdb, key);
414 if (NT_STATUS_IS_OK(status)) {
418 TALLOC_FREE(key.dptr);
423 /****************************************************************************
424 Receive and dispatch any messages pending for this process.
425 JRA changed Dec 13 2006. Only one message handler now permitted per type.
426 *NOTE*: Dispatch functions must be able to cope with incoming
427 messages on an *odd* byte boundary.
428 ****************************************************************************/
430 static void message_dispatch(struct messaging_context *msg_ctx)
432 struct messaging_tdb_context *ctx = talloc_get_type(msg_ctx->local->private_data,
433 struct messaging_tdb_context);
434 struct messaging_array *msg_array = NULL;
435 struct tdb_wrap *tdb = ctx->tdb;
439 if (ctx->received_messages == 0) {
443 DEBUG(10, ("message_dispatch: received_messages = %d\n",
444 ctx->received_messages));
446 status = retrieve_all_messages(tdb->tdb, NULL, &msg_array);
447 if (!NT_STATUS_IS_OK(status)) {
448 DEBUG(0, ("message_dispatch: failed to retrieve messages: %s\n",
453 ctx->received_messages = 0;
455 for (i=0; i<msg_array->num_messages; i++) {
456 messaging_dispatch_rec(msg_ctx, &msg_array->messages[i]);
459 TALLOC_FREE(msg_array);