summaryrefslogtreecommitdiff
path: root/source4/lib/messages.c
diff options
context:
space:
mode:
Diffstat (limited to 'source4/lib/messages.c')
-rw-r--r--source4/lib/messages.c566
1 files changed, 566 insertions, 0 deletions
diff --git a/source4/lib/messages.c b/source4/lib/messages.c
new file mode 100644
index 0000000000..cb26b356bd
--- /dev/null
+++ b/source4/lib/messages.c
@@ -0,0 +1,566 @@
+/*
+ Unix SMB/CIFS implementation.
+ Samba internal messaging functions
+ Copyright (C) Andrew Tridgell 2000
+ Copyright (C) 2001 by Martin Pool
+ Copyright (C) 2002 by Jeremy Allison
+
+ 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"
+
+/* the locking database handle */
+static TDB_CONTEXT *tdb;
+static int received_signal;
+
+/* change the message version with any incompatible changes in the protocol */
+#define MESSAGE_VERSION 1
+
+struct message_rec {
+ int msg_version;
+ int msg_type;
+ pid_t dest;
+ pid_t src;
+ size_t len;
+};
+
+/* we have a linked list of dispatch handlers */
+static struct dispatch_fns {
+ struct dispatch_fns *next, *prev;
+ int msg_type;
+ void (*fn)(int msg_type, pid_t pid, void *buf, size_t len);
+} *dispatch_fns;
+
+/****************************************************************************
+ Notifications come in as signals.
+****************************************************************************/
+
+static void sig_usr1(void)
+{
+ received_signal = 1;
+ sys_select_signal();
+}
+
+/****************************************************************************
+ A useful function for testing the message system.
+****************************************************************************/
+
+static void ping_message(int msg_type, pid_t src, void *buf, size_t len)
+{
+ const char *msg = buf ? buf : "none";
+ DEBUG(1,("INFO: Received PING message from PID %u [%s]\n",(unsigned int)src, msg));
+ message_send_pid(src, MSG_PONG, buf, len, True);
+}
+
+/****************************************************************************
+ Initialise the messaging functions.
+****************************************************************************/
+
+BOOL message_init(void)
+{
+ TALLOC_CTX *mem_ctx;
+
+ if (tdb) return True;
+
+ mem_ctx = talloc_init("message_init");
+ if (!mem_ctx) {
+ DEBUG(0,("ERROR: No memory to initialise messages database\n"));
+ return False;
+ }
+ tdb = tdb_open_log(lock_path(mem_ctx, "messages.tdb"),
+ 0, TDB_CLEAR_IF_FIRST|TDB_DEFAULT,
+ O_RDWR|O_CREAT,0600);
+ talloc_destroy(mem_ctx);
+
+ if (!tdb) {
+ DEBUG(0,("ERROR: Failed to initialise messages database\n"));
+ return False;
+ }
+
+ CatchSignal(SIGUSR1, SIGNAL_CAST sig_usr1);
+
+ message_register(MSG_PING, ping_message);
+
+ return True;
+}
+
+/*******************************************************************
+ Form a static tdb key from a pid.
+******************************************************************/
+
+static TDB_DATA message_key_pid(pid_t pid)
+{
+ static char key[20];
+ TDB_DATA kbuf;
+
+ slprintf(key, sizeof(key)-1, "PID/%d", (int)pid);
+
+ kbuf.dptr = (char *)key;
+ kbuf.dsize = strlen(key)+1;
+ return kbuf;
+}
+
+/****************************************************************************
+ Notify a process that it has a message. If the process doesn't exist
+ then delete its record in the database.
+****************************************************************************/
+
+static BOOL message_notify(pid_t pid)
+{
+ /*
+ * Doing kill with a non-positive pid causes messages to be
+ * sent to places we don't want.
+ */
+
+ SMB_ASSERT(pid > 0);
+
+ if (kill(pid, SIGUSR1) == -1) {
+ if (errno == ESRCH) {
+ DEBUG(2,("pid %d doesn't exist - deleting messages record\n", (int)pid));
+ tdb_delete(tdb, message_key_pid(pid));
+ } else {
+ DEBUG(2,("message to process %d failed - %s\n", (int)pid, strerror(errno)));
+ }
+ return False;
+ }
+ return True;
+}
+
+/****************************************************************************
+ Send a message to a particular pid.
+****************************************************************************/
+
+static BOOL message_send_pid_internal(pid_t pid, int msg_type, const void *buf, size_t len,
+ BOOL duplicates_allowed, unsigned int timeout)
+{
+ TDB_DATA kbuf;
+ TDB_DATA dbuf;
+ TDB_DATA old_dbuf;
+ struct message_rec rec;
+ char *ptr;
+ struct message_rec prec;
+
+ /*
+ * Doing kill with a non-positive pid causes messages to be
+ * sent to places we don't want.
+ */
+
+ SMB_ASSERT(pid > 0);
+
+ rec.msg_version = MESSAGE_VERSION;
+ rec.msg_type = msg_type;
+ rec.dest = pid;
+ rec.src = getpid();
+ rec.len = len;
+
+ kbuf = message_key_pid(pid);
+
+ dbuf.dptr = (void *)malloc(len + sizeof(rec));
+ if (!dbuf.dptr)
+ return False;
+
+ memcpy(dbuf.dptr, &rec, sizeof(rec));
+ if (len > 0)
+ memcpy((void *)((char*)dbuf.dptr+sizeof(rec)), buf, len);
+
+ dbuf.dsize = len + sizeof(rec);
+
+ if (duplicates_allowed) {
+
+ /* If duplicates are allowed we can just append the message and return. */
+
+ /* lock the record for the destination */
+ if (timeout) {
+ if (tdb_chainlock_with_timeout(tdb, kbuf, timeout) == -1) {
+ DEBUG(0,("message_send_pid_internal: failed to get chainlock with timeout %ul.\n", timeout));
+ return False;
+ }
+ } else {
+ if (tdb_chainlock(tdb, kbuf) == -1) {
+ DEBUG(0,("message_send_pid_internal: failed to get chainlock.\n"));
+ return False;
+ }
+ }
+ tdb_append(tdb, kbuf, dbuf);
+ tdb_chainunlock(tdb, kbuf);
+
+ SAFE_FREE(dbuf.dptr);
+ errno = 0; /* paranoia */
+ return message_notify(pid);
+ }
+
+ /* lock the record for the destination */
+ if (timeout) {
+ if (tdb_chainlock_with_timeout(tdb, kbuf, timeout) == -1) {
+ DEBUG(0,("message_send_pid_internal: failed to get chainlock with timeout %ul.\n", timeout));
+ return False;
+ }
+ } else {
+ if (tdb_chainlock(tdb, kbuf) == -1) {
+ DEBUG(0,("message_send_pid_internal: failed to get chainlock.\n"));
+ return False;
+ }
+ }
+
+ old_dbuf = tdb_fetch(tdb, kbuf);
+
+ if (!old_dbuf.dptr) {
+ /* its a new record */
+
+ tdb_store(tdb, kbuf, dbuf, TDB_REPLACE);
+ tdb_chainunlock(tdb, kbuf);
+
+ SAFE_FREE(dbuf.dptr);
+ errno = 0; /* paranoia */
+ return message_notify(pid);
+ }
+
+ /* Not a new record. Check for duplicates. */
+
+ for(ptr = (char *)old_dbuf.dptr; ptr < old_dbuf.dptr + old_dbuf.dsize; ) {
+ /*
+ * First check if the message header matches, then, if it's a non-zero
+ * sized message, check if the data matches. If so it's a duplicate and
+ * we can discard it. JRA.
+ */
+
+ if (!memcmp(ptr, &rec, sizeof(rec))) {
+ if (!len || (len && !memcmp( ptr + sizeof(rec), buf, len))) {
+ tdb_chainunlock(tdb, kbuf);
+ DEBUG(10,("message_send_pid_internal: discarding duplicate message.\n"));
+ SAFE_FREE(dbuf.dptr);
+ SAFE_FREE(old_dbuf.dptr);
+ return True;
+ }
+ }
+ memcpy(&prec, ptr, sizeof(prec));
+ ptr += sizeof(rec) + prec.len;
+ }
+
+ /* we're adding to an existing entry */
+
+ tdb_append(tdb, kbuf, dbuf);
+ tdb_chainunlock(tdb, kbuf);
+
+ SAFE_FREE(old_dbuf.dptr);
+ SAFE_FREE(dbuf.dptr);
+
+ errno = 0; /* paranoia */
+ return message_notify(pid);
+}
+
+/****************************************************************************
+ Send a message to a particular pid - no timeout.
+****************************************************************************/
+
+BOOL message_send_pid(pid_t pid, int msg_type, const void *buf, size_t len, BOOL duplicates_allowed)
+{
+ return message_send_pid_internal(pid, msg_type, buf, len, duplicates_allowed, 0);
+}
+
+/****************************************************************************
+ Send a message to a particular pid, with timeout in seconds.
+****************************************************************************/
+
+BOOL message_send_pid_with_timeout(pid_t pid, int msg_type, const void *buf, size_t len,
+ BOOL duplicates_allowed, unsigned int timeout)
+{
+ return message_send_pid_internal(pid, msg_type, buf, len, duplicates_allowed, timeout);
+}
+
+/****************************************************************************
+ Retrieve all messages for the current process.
+****************************************************************************/
+
+static BOOL retrieve_all_messages(char **msgs_buf, size_t *total_len)
+{
+ TDB_DATA kbuf;
+ TDB_DATA dbuf;
+ TDB_DATA null_dbuf;
+
+ ZERO_STRUCT(null_dbuf);
+
+ *msgs_buf = NULL;
+ *total_len = 0;
+
+ kbuf = message_key_pid(getpid());
+
+ tdb_chainlock(tdb, kbuf);
+ dbuf = tdb_fetch(tdb, kbuf);
+ /*
+ * Replace with an empty record to keep the allocated
+ * space in the tdb.
+ */
+ tdb_store(tdb, kbuf, null_dbuf, TDB_REPLACE);
+ tdb_chainunlock(tdb, kbuf);
+
+ if (dbuf.dptr == NULL || dbuf.dsize == 0) {
+ SAFE_FREE(dbuf.dptr);
+ return False;
+ }
+
+ *msgs_buf = dbuf.dptr;
+ *total_len = dbuf.dsize;
+
+ return True;
+}
+
+/****************************************************************************
+ Parse out the next message for the current process.
+****************************************************************************/
+
+static BOOL message_recv(char *msgs_buf, size_t total_len, int *msg_type, pid_t *src, char **buf, size_t *len)
+{
+ struct message_rec rec;
+ char *ret_buf = *buf;
+
+ *buf = NULL;
+ *len = 0;
+
+ if (total_len - (ret_buf - msgs_buf) < sizeof(rec))
+ return False;
+
+ memcpy(&rec, ret_buf, sizeof(rec));
+ ret_buf += sizeof(rec);
+
+ if (rec.msg_version != MESSAGE_VERSION) {
+ DEBUG(0,("message version %d received (expected %d)\n", rec.msg_version, MESSAGE_VERSION));
+ return False;
+ }
+
+ if (rec.len > 0) {
+ if (total_len - (ret_buf - msgs_buf) < rec.len)
+ return False;
+ }
+
+ *len = rec.len;
+ *msg_type = rec.msg_type;
+ *src = rec.src;
+ *buf = ret_buf;
+
+ return True;
+}
+
+/****************************************************************************
+ Receive and dispatch any messages pending for this process.
+ Notice that all dispatch handlers for a particular msg_type get called,
+ so you can register multiple handlers for a message.
+ *NOTE*: Dispatch functions must be able to cope with incoming
+ messages on an *odd* byte boundary.
+****************************************************************************/
+
+void message_dispatch(void)
+{
+ int msg_type;
+ pid_t src;
+ char *buf;
+ char *msgs_buf;
+ size_t len, total_len;
+ struct dispatch_fns *dfn;
+ int n_handled;
+
+ if (!received_signal)
+ return;
+
+ DEBUG(10,("message_dispatch: received_signal = %d\n", received_signal));
+
+ received_signal = 0;
+
+ if (!retrieve_all_messages(&msgs_buf, &total_len))
+ return;
+
+ for (buf = msgs_buf; message_recv(msgs_buf, total_len, &msg_type, &src, &buf, &len); buf += len) {
+ DEBUG(10,("message_dispatch: received msg_type=%d src_pid=%u\n",
+ msg_type, (unsigned int) src));
+ n_handled = 0;
+ for (dfn = dispatch_fns; dfn; dfn = dfn->next) {
+ if (dfn->msg_type == msg_type) {
+ DEBUG(10,("message_dispatch: processing message of type %d.\n", msg_type));
+ dfn->fn(msg_type, src, len ? (void *)buf : NULL, len);
+ n_handled++;
+ }
+ }
+ if (!n_handled) {
+ DEBUG(5,("message_dispatch: warning: no handlers registed for "
+ "msg_type %d in pid %u\n",
+ msg_type, (unsigned int)getpid()));
+ }
+ }
+ SAFE_FREE(msgs_buf);
+}
+
+/****************************************************************************
+ Register a dispatch function for a particular message type.
+ *NOTE*: Dispatch functions must be able to cope with incoming
+ messages on an *odd* byte boundary.
+****************************************************************************/
+
+void message_register(int msg_type,
+ void (*fn)(int msg_type, pid_t pid, void *buf, size_t len))
+{
+ struct dispatch_fns *dfn;
+
+ dfn = (struct dispatch_fns *)malloc(sizeof(*dfn));
+
+ if (dfn != NULL) {
+
+ ZERO_STRUCTPN(dfn);
+
+ dfn->msg_type = msg_type;
+ dfn->fn = fn;
+
+ DLIST_ADD(dispatch_fns, dfn);
+ }
+ else {
+
+ DEBUG(0,("message_register: Not enough memory. malloc failed!\n"));
+ }
+}
+
+/****************************************************************************
+ De-register the function for a particular message type.
+****************************************************************************/
+
+void message_deregister(int msg_type)
+{
+ struct dispatch_fns *dfn, *next;
+
+ for (dfn = dispatch_fns; dfn; dfn = next) {
+ next = dfn->next;
+ if (dfn->msg_type == msg_type) {
+ DLIST_REMOVE(dispatch_fns, dfn);
+ SAFE_FREE(dfn);
+ }
+ }
+}
+
+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 %u doesn't exist - deleting connections %d [%s]\n",
+ (unsigned int)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 < 3000)
+ msg_all.msg_flag = FLAG_MSG_PRINTING;
+ 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;
+}
+/** @} **/
generated by cgit (git 2.34.1) at 2024-06-29 23:08:46 +0000