mirror of
https://github.com/samba-team/samba.git
synced 2024-12-24 21:34:56 +03:00
7f5fefb7bb
per type - this is all we use right now and makes
re-entrancy problems with deleting handlers with
a message dispatch loop go away.
Jeremy.
(This used to be commit 2e9b6faeae
)
675 lines
18 KiB
C
675 lines
18 KiB
C
/*
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Unix SMB/CIFS implementation.
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Samba internal messaging functions
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Copyright (C) Andrew Tridgell 2000
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Copyright (C) 2001 by Martin Pool
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Copyright (C) 2002 by Jeremy Allison
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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/**
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@defgroup messages Internal messaging framework
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@{
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@file messages.c
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@brief Module for internal messaging between Samba daemons.
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The idea is that if a part of Samba wants to do communication with
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another Samba process then it will do a message_register() of a
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dispatch function, and use message_send_pid() to send messages to
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that process.
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The dispatch function is given the pid of the sender, and it can
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use that to reply by message_send_pid(). See ping_message() for a
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simple example.
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@caution Dispatch functions must be able to cope with incoming
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messages on an *odd* byte boundary.
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This system doesn't have any inherent size limitations but is not
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very efficient for large messages or when messages are sent in very
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quick succession.
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*/
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#include "includes.h"
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/* the locking database handle */
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static TDB_CONTEXT *tdb;
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static int received_signal;
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/* change the message version with any incompatible changes in the protocol */
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#define MESSAGE_VERSION 1
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struct message_rec {
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int msg_version;
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int msg_type;
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struct process_id dest;
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struct process_id src;
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size_t len;
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};
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/* we have a linked list of dispatch handlers */
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static struct dispatch_fns {
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struct dispatch_fns *next, *prev;
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int msg_type;
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void (*fn)(int msg_type, struct process_id pid, void *buf, size_t len);
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} *dispatch_fns;
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/****************************************************************************
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Free global objects.
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****************************************************************************/
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void gfree_messages(void)
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{
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struct dispatch_fns *dfn, *next;
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/* delete the dispatch_fns list */
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dfn = dispatch_fns;
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while( dfn ) {
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next = dfn->next;
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DLIST_REMOVE(dispatch_fns, dfn);
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SAFE_FREE(dfn);
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dfn = next;
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}
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}
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/****************************************************************************
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Notifications come in as signals.
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****************************************************************************/
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static void sig_usr1(void)
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{
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received_signal = 1;
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sys_select_signal(SIGUSR1);
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}
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/****************************************************************************
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A useful function for testing the message system.
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****************************************************************************/
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static void ping_message(int msg_type, struct process_id src,
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void *buf, size_t len)
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{
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const char *msg = buf ? (const char *)buf : "none";
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DEBUG(1,("INFO: Received PING message from PID %s [%s]\n",
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procid_str_static(&src), msg));
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message_send_pid(src, MSG_PONG, buf, len, True);
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}
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/****************************************************************************
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Initialise the messaging functions.
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****************************************************************************/
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BOOL message_init(void)
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{
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sec_init();
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if (tdb)
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return True;
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tdb = tdb_open_log(lock_path("messages.tdb"),
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0, TDB_CLEAR_IF_FIRST|TDB_DEFAULT,
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O_RDWR|O_CREAT,0600);
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if (!tdb) {
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DEBUG(0,("ERROR: Failed to initialise messages database\n"));
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return False;
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}
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CatchSignal(SIGUSR1, SIGNAL_CAST sig_usr1);
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message_register(MSG_PING, ping_message);
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/* Register some debugging related messages */
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register_msg_pool_usage();
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register_dmalloc_msgs();
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return True;
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}
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/*******************************************************************
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Form a static tdb key from a pid.
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******************************************************************/
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static TDB_DATA message_key_pid(struct process_id pid)
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{
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static char key[20];
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TDB_DATA kbuf;
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slprintf(key, sizeof(key)-1, "PID/%s", procid_str_static(&pid));
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kbuf.dptr = (char *)key;
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kbuf.dsize = strlen(key)+1;
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return kbuf;
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}
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/****************************************************************************
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Notify a process that it has a message. If the process doesn't exist
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then delete its record in the database.
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****************************************************************************/
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static BOOL message_notify(struct process_id procid)
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{
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pid_t pid = procid.pid;
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int ret;
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uid_t euid = geteuid();
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/*
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* Doing kill with a non-positive pid causes messages to be
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* sent to places we don't want.
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*/
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SMB_ASSERT(pid > 0);
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if (euid != 0) {
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become_root_uid_only();
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}
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ret = kill(pid, SIGUSR1);
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if (euid != 0) {
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unbecome_root_uid_only();
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}
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if (ret == -1) {
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if (errno == ESRCH) {
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DEBUG(2,("pid %d doesn't exist - deleting messages record\n", (int)pid));
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tdb_delete(tdb, message_key_pid(procid));
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} else {
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DEBUG(2,("message to process %d failed - %s\n", (int)pid, strerror(errno)));
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}
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return False;
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}
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return True;
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}
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/****************************************************************************
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Send a message to a particular pid.
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****************************************************************************/
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static BOOL message_send_pid_internal(struct process_id pid, int msg_type,
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const void *buf, size_t len,
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BOOL duplicates_allowed,
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unsigned int timeout)
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{
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TDB_DATA kbuf;
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TDB_DATA dbuf;
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TDB_DATA old_dbuf;
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struct message_rec rec;
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char *ptr;
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struct message_rec prec;
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/* NULL pointer means implicit length zero. */
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if (!buf) {
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SMB_ASSERT(len == 0);
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}
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/*
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* Doing kill with a non-positive pid causes messages to be
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* sent to places we don't want.
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*/
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SMB_ASSERT(procid_to_pid(&pid) > 0);
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rec.msg_version = MESSAGE_VERSION;
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rec.msg_type = msg_type;
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rec.dest = pid;
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rec.src = procid_self();
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rec.len = buf ? len : 0;
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kbuf = message_key_pid(pid);
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dbuf.dptr = (char *)SMB_MALLOC(len + sizeof(rec));
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if (!dbuf.dptr)
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return False;
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memcpy(dbuf.dptr, &rec, sizeof(rec));
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if (len > 0 && buf)
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memcpy((void *)((char*)dbuf.dptr+sizeof(rec)), buf, len);
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dbuf.dsize = len + sizeof(rec);
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if (duplicates_allowed) {
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/* If duplicates are allowed we can just append the message and return. */
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/* lock the record for the destination */
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if (timeout) {
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if (tdb_chainlock_with_timeout(tdb, kbuf, timeout) == -1) {
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DEBUG(0,("message_send_pid_internal: failed to get chainlock with timeout %ul.\n", timeout));
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return False;
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}
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} else {
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if (tdb_chainlock(tdb, kbuf) == -1) {
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DEBUG(0,("message_send_pid_internal: failed to get chainlock.\n"));
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return False;
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}
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}
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tdb_append(tdb, kbuf, dbuf);
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tdb_chainunlock(tdb, kbuf);
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SAFE_FREE(dbuf.dptr);
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errno = 0; /* paranoia */
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return message_notify(pid);
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}
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/* lock the record for the destination */
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if (timeout) {
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if (tdb_chainlock_with_timeout(tdb, kbuf, timeout) == -1) {
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DEBUG(0,("message_send_pid_internal: failed to get chainlock with timeout %ul.\n", timeout));
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return False;
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}
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} else {
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if (tdb_chainlock(tdb, kbuf) == -1) {
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DEBUG(0,("message_send_pid_internal: failed to get chainlock.\n"));
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return False;
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}
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}
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old_dbuf = tdb_fetch(tdb, kbuf);
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if (!old_dbuf.dptr) {
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/* its a new record */
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tdb_store(tdb, kbuf, dbuf, TDB_REPLACE);
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tdb_chainunlock(tdb, kbuf);
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SAFE_FREE(dbuf.dptr);
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errno = 0; /* paranoia */
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return message_notify(pid);
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}
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/* Not a new record. Check for duplicates. */
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for(ptr = (char *)old_dbuf.dptr; ptr < old_dbuf.dptr + old_dbuf.dsize; ) {
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/*
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* First check if the message header matches, then, if it's a non-zero
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* sized message, check if the data matches. If so it's a duplicate and
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* we can discard it. JRA.
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*/
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if (!memcmp(ptr, &rec, sizeof(rec))) {
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if (!len || (len && !memcmp( ptr + sizeof(rec), buf, len))) {
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tdb_chainunlock(tdb, kbuf);
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DEBUG(10,("message_send_pid_internal: discarding duplicate message.\n"));
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SAFE_FREE(dbuf.dptr);
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SAFE_FREE(old_dbuf.dptr);
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return True;
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}
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}
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memcpy(&prec, ptr, sizeof(prec));
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ptr += sizeof(rec) + prec.len;
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}
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/* we're adding to an existing entry */
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tdb_append(tdb, kbuf, dbuf);
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tdb_chainunlock(tdb, kbuf);
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SAFE_FREE(old_dbuf.dptr);
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SAFE_FREE(dbuf.dptr);
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errno = 0; /* paranoia */
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return message_notify(pid);
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}
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/****************************************************************************
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Send a message to a particular pid - no timeout.
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****************************************************************************/
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BOOL message_send_pid(struct process_id pid, int msg_type, const void *buf, size_t len, BOOL duplicates_allowed)
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{
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return message_send_pid_internal(pid, msg_type, buf, len, duplicates_allowed, 0);
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}
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/****************************************************************************
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Send a message to a particular pid, with timeout in seconds.
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****************************************************************************/
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BOOL message_send_pid_with_timeout(struct process_id pid, int msg_type, const void *buf, size_t len,
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BOOL duplicates_allowed, unsigned int timeout)
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{
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return message_send_pid_internal(pid, msg_type, buf, len, duplicates_allowed, timeout);
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}
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/****************************************************************************
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Count the messages pending for a particular pid. Expensive....
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****************************************************************************/
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unsigned int messages_pending_for_pid(struct process_id pid)
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{
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TDB_DATA kbuf;
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TDB_DATA dbuf;
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char *buf;
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unsigned int message_count = 0;
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kbuf = message_key_pid(pid);
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dbuf = tdb_fetch(tdb, kbuf);
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if (dbuf.dptr == NULL || dbuf.dsize == 0) {
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SAFE_FREE(dbuf.dptr);
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return 0;
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}
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for (buf = dbuf.dptr; dbuf.dsize > sizeof(struct message_rec);) {
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struct message_rec rec;
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memcpy(&rec, buf, sizeof(rec));
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buf += (sizeof(rec) + rec.len);
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dbuf.dsize -= (sizeof(rec) + rec.len);
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message_count++;
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}
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SAFE_FREE(dbuf.dptr);
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return message_count;
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}
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/****************************************************************************
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Retrieve all messages for the current process.
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****************************************************************************/
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static BOOL retrieve_all_messages(char **msgs_buf, size_t *total_len)
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{
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TDB_DATA kbuf;
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TDB_DATA dbuf;
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TDB_DATA null_dbuf;
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ZERO_STRUCT(null_dbuf);
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*msgs_buf = NULL;
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*total_len = 0;
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kbuf = message_key_pid(pid_to_procid(sys_getpid()));
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if (tdb_chainlock(tdb, kbuf) == -1)
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return False;
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dbuf = tdb_fetch(tdb, kbuf);
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/*
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* Replace with an empty record to keep the allocated
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* space in the tdb.
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*/
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tdb_store(tdb, kbuf, null_dbuf, TDB_REPLACE);
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tdb_chainunlock(tdb, kbuf);
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if (dbuf.dptr == NULL || dbuf.dsize == 0) {
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SAFE_FREE(dbuf.dptr);
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return False;
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}
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*msgs_buf = dbuf.dptr;
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*total_len = dbuf.dsize;
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return True;
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}
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/****************************************************************************
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Parse out the next message for the current process.
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****************************************************************************/
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static BOOL message_recv(char *msgs_buf, size_t total_len, int *msg_type,
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struct process_id *src, char **buf, size_t *len)
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{
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struct message_rec rec;
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char *ret_buf = *buf;
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*buf = NULL;
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*len = 0;
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if (total_len - (ret_buf - msgs_buf) < sizeof(rec))
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return False;
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memcpy(&rec, ret_buf, sizeof(rec));
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ret_buf += sizeof(rec);
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if (rec.msg_version != MESSAGE_VERSION) {
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DEBUG(0,("message version %d received (expected %d)\n", rec.msg_version, MESSAGE_VERSION));
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return False;
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}
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if (rec.len > 0) {
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if (total_len - (ret_buf - msgs_buf) < rec.len)
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return False;
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}
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*len = rec.len;
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*msg_type = rec.msg_type;
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*src = rec.src;
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*buf = ret_buf;
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return True;
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}
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/****************************************************************************
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Receive and dispatch any messages pending for this process.
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JRA changed Dec 13 2006. Only one message handler now permitted per type.
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*NOTE*: Dispatch functions must be able to cope with incoming
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messages on an *odd* byte boundary.
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****************************************************************************/
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void message_dispatch(void)
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{
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int msg_type;
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struct process_id src;
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char *buf;
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char *msgs_buf;
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size_t len, total_len;
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int n_handled;
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if (!received_signal)
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return;
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DEBUG(10,("message_dispatch: received_signal = %d\n", received_signal));
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received_signal = 0;
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if (!retrieve_all_messages(&msgs_buf, &total_len))
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return;
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for (buf = msgs_buf; message_recv(msgs_buf, total_len, &msg_type, &src, &buf, &len); buf += len) {
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struct dispatch_fns *dfn, *next;
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DEBUG(10,("message_dispatch: received msg_type=%d "
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"src_pid=%u\n", msg_type,
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(unsigned int) procid_to_pid(&src)));
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n_handled = 0;
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for (dfn = dispatch_fns; dfn; dfn = next) {
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next = dfn->next;
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if (dfn->msg_type == msg_type) {
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DEBUG(10,("message_dispatch: processing message of type %d.\n", msg_type));
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dfn->fn(msg_type, src, len ? (void *)buf : NULL, len);
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n_handled++;
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}
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}
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if (!n_handled) {
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DEBUG(5,("message_dispatch: warning: no handlers registed for "
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"msg_type %d in pid %u\n",
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msg_type, (unsigned int)sys_getpid()));
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}
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}
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SAFE_FREE(msgs_buf);
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}
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/****************************************************************************
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Register/replace a dispatch function for a particular message type.
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JRA changed Dec 13 2006. Only one message handler now permitted per type.
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*NOTE*: Dispatch functions must be able to cope with incoming
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messages on an *odd* byte boundary.
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****************************************************************************/
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void message_register(int msg_type,
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void (*fn)(int msg_type, struct process_id pid,
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void *buf, size_t len))
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{
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struct dispatch_fns *dfn;
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for (dfn = dispatch_fns; dfn; dfn = dfn->next) {
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if (dfn->msg_type == msg_type) {
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dfn->fn = fn;
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return;
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}
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}
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dfn = SMB_MALLOC_P(struct dispatch_fns);
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if (dfn != NULL) {
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ZERO_STRUCTPN(dfn);
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dfn->msg_type = msg_type;
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dfn->fn = fn;
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DLIST_ADD(dispatch_fns, dfn);
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}
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else {
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DEBUG(0,("message_register: Not enough memory. malloc failed!\n"));
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}
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}
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/****************************************************************************
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De-register the function for a particular message type.
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****************************************************************************/
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void message_deregister(int msg_type)
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{
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struct dispatch_fns *dfn, *next;
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for (dfn = dispatch_fns; dfn; dfn = next) {
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next = dfn->next;
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if (dfn->msg_type == msg_type) {
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DLIST_REMOVE(dispatch_fns, dfn);
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SAFE_FREE(dfn);
|
|
return;
|
|
}
|
|
}
|
|
}
|
|
|
|
struct msg_all {
|
|
int msg_type;
|
|
uint32 msg_flag;
|
|
const void *buf;
|
|
size_t len;
|
|
BOOL duplicates;
|
|
int n_sent;
|
|
};
|
|
|
|
/****************************************************************************
|
|
Send one of the messages for the broadcast.
|
|
****************************************************************************/
|
|
|
|
static int traverse_fn(TDB_CONTEXT *the_tdb, TDB_DATA kbuf, TDB_DATA dbuf, void *state)
|
|
{
|
|
struct connections_data crec;
|
|
struct msg_all *msg_all = (struct msg_all *)state;
|
|
|
|
if (dbuf.dsize != sizeof(crec))
|
|
return 0;
|
|
|
|
memcpy(&crec, dbuf.dptr, sizeof(crec));
|
|
|
|
if (crec.cnum != -1)
|
|
return 0;
|
|
|
|
/* Don't send if the receiver hasn't registered an interest. */
|
|
|
|
if(!(crec.bcast_msg_flags & msg_all->msg_flag))
|
|
return 0;
|
|
|
|
/* If the msg send fails because the pid was not found (i.e. smbd died),
|
|
* the msg has already been deleted from the messages.tdb.*/
|
|
|
|
if (!message_send_pid(crec.pid, msg_all->msg_type,
|
|
msg_all->buf, msg_all->len,
|
|
msg_all->duplicates)) {
|
|
|
|
/* If the pid was not found delete the entry from connections.tdb */
|
|
|
|
if (errno == ESRCH) {
|
|
DEBUG(2,("pid %s doesn't exist - deleting connections %d [%s]\n",
|
|
procid_str_static(&crec.pid),
|
|
crec.cnum, crec.name));
|
|
tdb_delete(the_tdb, kbuf);
|
|
}
|
|
}
|
|
msg_all->n_sent++;
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* Send a message to all smbd processes.
|
|
*
|
|
* It isn't very efficient, but should be OK for the sorts of
|
|
* applications that use it. When we need efficient broadcast we can add
|
|
* it.
|
|
*
|
|
* @param n_sent Set to the number of messages sent. This should be
|
|
* equal to the number of processes, but be careful for races.
|
|
*
|
|
* @retval True for success.
|
|
**/
|
|
BOOL message_send_all(TDB_CONTEXT *conn_tdb, int msg_type,
|
|
const void *buf, size_t len,
|
|
BOOL duplicates_allowed,
|
|
int *n_sent)
|
|
{
|
|
struct msg_all msg_all;
|
|
|
|
msg_all.msg_type = msg_type;
|
|
if (msg_type < 1000)
|
|
msg_all.msg_flag = FLAG_MSG_GENERAL;
|
|
else if (msg_type > 1000 && msg_type < 2000)
|
|
msg_all.msg_flag = FLAG_MSG_NMBD;
|
|
else if (msg_type > 2000 && msg_type < 2100)
|
|
msg_all.msg_flag = FLAG_MSG_PRINT_NOTIFY;
|
|
else if (msg_type > 2100 && msg_type < 3000)
|
|
msg_all.msg_flag = FLAG_MSG_PRINT_GENERAL;
|
|
else if (msg_type > 3000 && msg_type < 4000)
|
|
msg_all.msg_flag = FLAG_MSG_SMBD;
|
|
else
|
|
return False;
|
|
|
|
msg_all.buf = buf;
|
|
msg_all.len = len;
|
|
msg_all.duplicates = duplicates_allowed;
|
|
msg_all.n_sent = 0;
|
|
|
|
tdb_traverse(conn_tdb, traverse_fn, &msg_all);
|
|
if (n_sent)
|
|
*n_sent = msg_all.n_sent;
|
|
return True;
|
|
}
|
|
|
|
/*
|
|
* Block and unblock receiving of messages. Allows removal of race conditions
|
|
* when doing a fork and changing message disposition.
|
|
*/
|
|
|
|
void message_block(void)
|
|
{
|
|
BlockSignals(True, SIGUSR1);
|
|
}
|
|
|
|
void message_unblock(void)
|
|
{
|
|
BlockSignals(False, SIGUSR1);
|
|
}
|
|
/** @} **/
|