messages.c

samba-3.0.22.tar.gz 编译smb服务器的源码

BOOL message_send_pid_with_timeout(struct process_id 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);
}

/****************************************************************************
 Count the messages pending for a particular pid. Expensive....
****************************************************************************/

unsigned int messages_pending_for_pid(struct process_id pid)
{
	TDB_DATA kbuf;
	TDB_DATA dbuf;
	char *buf;
	unsigned int message_count = 0;

	kbuf = message_key_pid(pid);

	dbuf = tdb_fetch(tdb, kbuf);
	if (dbuf.dptr == NULL || dbuf.dsize == 0) {
		SAFE_FREE(dbuf.dptr);
		return 0;
	}

	for (buf = dbuf.dptr; dbuf.dsize > sizeof(struct message_rec);) {
		struct message_rec rec;
		memcpy(&rec, buf, sizeof(rec));
		buf += (sizeof(rec) + rec.len);
		dbuf.dsize -= (sizeof(rec) + rec.len);
		message_count++;
	}

	SAFE_FREE(dbuf.dptr);
	return message_count;
}

/****************************************************************************
 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(pid_to_procid(sys_getpid()));

	if (tdb_chainlock(tdb, kbuf) == -1)
		return False;

	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,
			 struct process_id *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;
	struct process_id 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) procid_to_pid(&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)sys_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, struct process_id pid,
				 void *buf, size_t len))
{
	struct dispatch_fns *dfn;

	dfn = SMB_MALLOC_P(struct dispatch_fns);

	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 %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;
}
/** @} **/