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samba-mirror/source3/lib/messages_local.c
Volker Lendecke b05c7b9783 r23408: Remove a bogus comment
(This used to be commit 0442e680ee)
2007-10-10 12:23:14 -05:00

433 lines
11 KiB
C

/*
Unix SMB/CIFS implementation.
Samba internal messaging functions
Copyright (C) 2007 by Volker Lendecke
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
/**
@defgroup messages Internal messaging framework
@{
@file messages.c
@brief Module for internal messaging between Samba daemons.
The idea is that if a part of Samba wants to do communication with
another Samba process then it will do a message_register() of a
dispatch function, and use message_send_pid() to send messages to
that process.
The dispatch function is given the pid of the sender, and it can
use that to reply by message_send_pid(). See ping_message() for a
simple example.
@caution Dispatch functions must be able to cope with incoming
messages on an *odd* byte boundary.
This system doesn't have any inherent size limitations but is not
very efficient for large messages or when messages are sent in very
quick succession.
*/
#include "includes.h"
#include "librpc/gen_ndr/messaging.h"
#include "librpc/gen_ndr/ndr_messaging.h"
static int received_signal;
static NTSTATUS messaging_tdb_send(struct messaging_context *msg_ctx,
struct server_id pid, int msg_type,
const DATA_BLOB *data,
struct messaging_backend *backend);
/****************************************************************************
Notifications come in as signals.
****************************************************************************/
static void sig_usr1(void)
{
received_signal = 1;
sys_select_signal(SIGUSR1);
}
static int messaging_tdb_destructor(struct messaging_backend *tdb_ctx)
{
TDB_CONTEXT *tdb = (TDB_CONTEXT *)tdb_ctx->private_data;
tdb_close(tdb);
return 0;
}
/****************************************************************************
Initialise the messaging functions.
****************************************************************************/
NTSTATUS messaging_tdb_init(struct messaging_context *msg_ctx,
TALLOC_CTX *mem_ctx,
struct messaging_backend **presult)
{
struct messaging_backend *result;
TDB_CONTEXT *tdb;
if (!(result = TALLOC_P(mem_ctx, struct messaging_backend))) {
DEBUG(0, ("talloc failed\n"));
return NT_STATUS_NO_MEMORY;
}
tdb = tdb_open_log(lock_path("messages.tdb"),
0, TDB_CLEAR_IF_FIRST|TDB_DEFAULT,
O_RDWR|O_CREAT,0600);
if (!tdb) {
NTSTATUS status = map_nt_error_from_unix(errno);
DEBUG(0, ("ERROR: Failed to initialise messages database: "
"%s\n", strerror(errno)));
TALLOC_FREE(result);
return status;
}
sec_init();
/* Activate the per-hashchain freelist */
tdb_set_max_dead(tdb, 5);
CatchSignal(SIGUSR1, SIGNAL_CAST sig_usr1);
result->private_data = (void *)tdb;
result->send_fn = messaging_tdb_send;
talloc_set_destructor(result, messaging_tdb_destructor);
*presult = result;
return NT_STATUS_OK;
}
/*******************************************************************
Form a static tdb key from a pid.
******************************************************************/
static TDB_DATA message_key_pid(struct server_id pid)
{
static char key[20];
TDB_DATA kbuf;
slprintf(key, sizeof(key)-1, "PID/%s", procid_str_static(&pid));
kbuf.dptr = (uint8 *)key;
kbuf.dsize = strlen(key)+1;
return kbuf;
}
/*
Fetch the messaging array for a process
*/
static NTSTATUS messaging_tdb_fetch(TDB_CONTEXT *msg_tdb,
TDB_DATA key,
TALLOC_CTX *mem_ctx,
struct messaging_array **presult)
{
struct messaging_array *result;
TDB_DATA data;
DATA_BLOB blob;
NTSTATUS status;
if (!(result = TALLOC_ZERO_P(mem_ctx, struct messaging_array))) {
return NT_STATUS_NO_MEMORY;
}
data = tdb_fetch(msg_tdb, key);
if (data.dptr == NULL) {
*presult = result;
return NT_STATUS_OK;
}
blob = data_blob_const(data.dptr, data.dsize);
status = ndr_pull_struct_blob(
&blob, result, result,
(ndr_pull_flags_fn_t)ndr_pull_messaging_array);
SAFE_FREE(data.dptr);
if (!NT_STATUS_IS_OK(status)) {
TALLOC_FREE(result);
return status;
}
if (DEBUGLEVEL >= 10) {
DEBUG(10, ("messaging_tdb_fetch:\n"));
NDR_PRINT_DEBUG(messaging_array, result);
}
*presult = result;
return NT_STATUS_OK;
}
/*
Store a messaging array for a pid
*/
static NTSTATUS messaging_tdb_store(TDB_CONTEXT *msg_tdb,
TDB_DATA key,
struct messaging_array *array)
{
TDB_DATA data;
DATA_BLOB blob;
NTSTATUS status;
TALLOC_CTX *mem_ctx;
int ret;
if (array->num_messages == 0) {
tdb_delete(msg_tdb, key);
return NT_STATUS_OK;
}
if (!(mem_ctx = talloc_new(array))) {
return NT_STATUS_NO_MEMORY;
}
status = ndr_push_struct_blob(
&blob, mem_ctx, array,
(ndr_push_flags_fn_t)ndr_push_messaging_array);
if (!NT_STATUS_IS_OK(status)) {
talloc_free(mem_ctx);
return status;
}
if (DEBUGLEVEL >= 10) {
DEBUG(10, ("messaging_tdb_store:\n"));
NDR_PRINT_DEBUG(messaging_array, array);
}
data.dptr = blob.data;
data.dsize = blob.length;
ret = tdb_store(msg_tdb, key, data, TDB_REPLACE);
TALLOC_FREE(mem_ctx);
return (ret == 0) ? NT_STATUS_OK : NT_STATUS_INTERNAL_DB_CORRUPTION;
}
/****************************************************************************
Notify a process that it has a message. If the process doesn't exist
then delete its record in the database.
****************************************************************************/
static NTSTATUS message_notify(struct server_id procid)
{
pid_t pid = procid.pid;
int ret;
uid_t euid = geteuid();
/*
* Doing kill with a non-positive pid causes messages to be
* sent to places we don't want.
*/
SMB_ASSERT(pid > 0);
if (euid != 0) {
/* If we're not root become so to send the message. */
save_re_uid();
set_effective_uid(0);
}
ret = kill(pid, SIGUSR1);
if (euid != 0) {
/* Go back to who we were. */
int saved_errno = errno;
restore_re_uid_fromroot();
errno = saved_errno;
}
if (ret == 0) {
return NT_STATUS_OK;
}
/*
* Something has gone wrong
*/
DEBUG(2,("message to process %d failed - %s\n", (int)pid,
strerror(errno)));
/*
* No call to map_nt_error_from_unix -- don't want to link in
* errormap.o into lots of utils.
*/
if (errno == ESRCH) return NT_STATUS_INVALID_HANDLE;
if (errno == EINVAL) return NT_STATUS_INVALID_PARAMETER;
if (errno == EPERM) return NT_STATUS_ACCESS_DENIED;
return NT_STATUS_UNSUCCESSFUL;
}
/****************************************************************************
Send a message to a particular pid.
****************************************************************************/
static NTSTATUS messaging_tdb_send(struct messaging_context *msg_ctx,
struct server_id pid, int msg_type,
const DATA_BLOB *data,
struct messaging_backend *backend)
{
struct messaging_array *msg_array;
struct messaging_rec *rec;
TALLOC_CTX *mem_ctx;
NTSTATUS status;
TDB_DATA key = message_key_pid(pid);
TDB_CONTEXT *tdb = (TDB_CONTEXT *)backend->private_data;
/* NULL pointer means implicit length zero. */
if (!data->data) {
SMB_ASSERT(data->length == 0);
}
/*
* Doing kill with a non-positive pid causes messages to be
* sent to places we don't want.
*/
SMB_ASSERT(procid_to_pid(&pid) > 0);
if (!(mem_ctx = talloc_init("message_send_pid"))) {
return NT_STATUS_NO_MEMORY;
}
if (tdb_chainlock(tdb, key) == -1) {
TALLOC_FREE(mem_ctx);
return NT_STATUS_LOCK_NOT_GRANTED;
}
status = messaging_tdb_fetch(tdb, key, mem_ctx, &msg_array);
if (!NT_STATUS_IS_OK(status)) {
goto done;
}
if ((msg_type & MSG_FLAG_LOWPRIORITY)
&& (msg_array->num_messages > 1000)) {
DEBUG(5, ("Dropping message for PID %s\n",
procid_str_static(&pid)));
status = NT_STATUS_INSUFFICIENT_RESOURCES;
goto done;
}
if (!(rec = TALLOC_REALLOC_ARRAY(mem_ctx, msg_array->messages,
struct messaging_rec,
msg_array->num_messages+1))) {
status = NT_STATUS_NO_MEMORY;
goto done;
}
rec[msg_array->num_messages].msg_version = MESSAGE_VERSION;
rec[msg_array->num_messages].msg_type = msg_type & MSG_TYPE_MASK;
rec[msg_array->num_messages].dest = pid;
rec[msg_array->num_messages].src = procid_self();
rec[msg_array->num_messages].buf = *data;
msg_array->messages = rec;
msg_array->num_messages += 1;
status = messaging_tdb_store(tdb, key, msg_array);
if (!NT_STATUS_IS_OK(status)) {
goto done;
}
status = message_notify(pid);
if (NT_STATUS_EQUAL(status, NT_STATUS_INVALID_HANDLE)) {
DEBUG(2, ("pid %s doesn't exist - deleting messages record\n",
procid_str_static(&pid)));
tdb_delete(tdb, message_key_pid(pid));
}
done:
tdb_chainunlock(tdb, key);
TALLOC_FREE(mem_ctx);
return status;
}
/****************************************************************************
Retrieve all messages for the current process.
****************************************************************************/
static NTSTATUS retrieve_all_messages(TDB_CONTEXT *msg_tdb,
TALLOC_CTX *mem_ctx,
struct messaging_array **presult)
{
struct messaging_array *result;
TDB_DATA key = message_key_pid(procid_self());
NTSTATUS status;
if (tdb_chainlock(msg_tdb, key) == -1) {
return NT_STATUS_LOCK_NOT_GRANTED;
}
status = messaging_tdb_fetch(msg_tdb, key, mem_ctx, &result);
/*
* We delete the record here, tdb_set_max_dead keeps it around
*/
tdb_delete(msg_tdb, key);
tdb_chainunlock(msg_tdb, key);
if (NT_STATUS_IS_OK(status)) {
*presult = result;
}
return status;
}
/****************************************************************************
Receive and dispatch any messages pending for this process.
JRA changed Dec 13 2006. Only one message handler now permitted per type.
*NOTE*: Dispatch functions must be able to cope with incoming
messages on an *odd* byte boundary.
****************************************************************************/
void message_dispatch(struct messaging_context *msg_ctx)
{
struct messaging_array *msg_array = NULL;
TDB_CONTEXT *tdb = (TDB_CONTEXT *)(msg_ctx->local->private_data);
uint32 i;
if (!received_signal)
return;
DEBUG(10, ("message_dispatch: received_signal = %d\n",
received_signal));
received_signal = 0;
if (!NT_STATUS_IS_OK(retrieve_all_messages(tdb, NULL, &msg_array))) {
return;
}
for (i=0; i<msg_array->num_messages; i++) {
messaging_dispatch_rec(msg_ctx, &msg_array->messages[i]);
}
TALLOC_FREE(msg_array);
}
/** @} **/