Adding upstream version 2.6.7+dfsg.upstream/2.6.7+dfsgupstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

23 files changed, 8503 insertions, 0 deletions

diff --git a/servers/slapd/back-monitor/Makefile.in b/servers/slapd/back-monitor/Makefile.in
new file mode 100644
index 0000000..e3b30a0
--- /dev/null
+++ b/servers/slapd/back-monitor/Makefile.in
@@ -0,0 +1,49 @@
+# Makefile.in for back-monitor
+# $OpenLDAP$
+## This work is part of OpenLDAP Software <http://www.openldap.org/>.
+##
+## Copyright 1998-2022 The OpenLDAP Foundation.
+## All rights reserved.
+##
+## Redistribution and use in source and binary forms, with or without
+## modification, are permitted only as authorized by the OpenLDAP
+## Public License.
+##
+## A copy of this license is available in the file LICENSE in the
+## top-level directory of the distribution or, alternatively, at
+## <http://www.OpenLDAP.org/license.html>.
+
+SRCS = init.c search.c compare.c modify.c bind.c \
+	operational.c \
+	cache.c entry.c \
+	backend.c database.c thread.c conn.c rww.c log.c \
+	operation.c sent.c listener.c time.c overlay.c
+OBJS = init.lo search.lo compare.lo modify.lo bind.lo \
+	operational.lo \
+	cache.lo entry.lo \
+	backend.lo database.lo thread.lo conn.lo rww.lo log.lo \
+	operation.lo sent.lo listener.lo time.lo overlay.lo
+
+LDAP_INCDIR= ../../../include
+LDAP_LIBDIR= ../../../libraries
+
+BUILD_OPT = "--enable-monitor"
+BUILD_MOD = yes
+
+mod_DEFS = -DSLAPD_IMPORT
+MOD_DEFS = $(yes_DEFS)
+
+shared_LDAP_LIBS = $(LDAP_LIBLDAP_LA) $(LDAP_LIBLBER_LA)
+NT_LINK_LIBS = -L.. -lslapd $(@BUILD_LIBS_DYNAMIC@_LDAP_LIBS)
+UNIX_LINK_LIBS = $(@BUILD_LIBS_DYNAMIC@_LDAP_LIBS)
+
+LIBBASE = back_monitor
+
+XINCPATH = -I.. -I$(srcdir)/.. -I$(srcdir)/../slapi
+XDEFS = $(MODULES_CPPFLAGS)
+
+all-local-lib:	../.backend
+
+../.backend: lib$(LIBBASE).a
+	@touch $@
+
diff --git a/servers/slapd/back-monitor/README b/servers/slapd/back-monitor/README
new file mode 100644
index 0000000..38dc360
--- /dev/null
+++ b/servers/slapd/back-monitor/README
@@ -0,0 +1,243 @@
+MONITOR BACKEND
+
+	NAME: 	back-monitor
+
+	Backend for monitoring the server's activity.
+
+
+
+COMPILE AND CONFIGURATION OPTIONS
+
+It must be explicitly enabled by configuring with 
+
+	--enable-monitor
+
+set; then it must be activated by placing in slapd.conf the database
+configure directive
+
+	database	monitor
+
+The suffix "cn=Monitor" is implicitly activated (it cannot be given
+as a suffix of the database as usually done for conventional backends).
+Note that the "cn=Monitor" naming context appears in the rootDSE
+in the attribute monitorContext
+
+A bind operation is provided; at present it allows to bind as the
+backend rootdn.  As a result, the backend supports the rootdn/rootpw 
+directives (only simple bind at present).
+
+
+
+NAMING CONTEXT AND TREE STRUCTURE
+
+The backend naming context is "cn=Monitor"; the first level entries 
+represent the monitored subsystems.  It is implemented in a modular way,
+to ease the addition of new subsystems.
+
+
+
+SCHEMA
+
+All the subsystems get a default "cn" attribute, represented by the
+subsystem's name, and they all have "top", "monitor" and "extensibleObject"
+objectclasses.
+"extensibleObject" is used, and the "description" attribute 
+is used to hold the monitor information of each entry.
+
+
+
+FUNCTIONALITY
+
+Most of the subsystems contain an additional depth level, represented
+by detailed item monitoring.
+All the entries undergo an update operation, if a related method is
+defined, prior to being returned.  Moreover, there's a mechanism to
+allow volatile entries to be defined, and generated on the fly when
+requested.  As an instance, the connection statistics are updated
+at each request, while each active connection data is created on the
+fly.
+
+One nice feature of this solution is that granular ACLs can be applied 
+to each entry.
+
+
+
+OPERATIONS
+
+The backend currently supports:
+
+	bind
+	compare
+	modify
+	search
+
+
+
+SUBSYSTEMS
+
+Currently some subsystems are partially supported.  "Partially"
+means their entries are correctly generated, but sometimes only 
+partially useful information is provided.
+
+The subsystems are:
+
+	Backends
+	Connections
+	Databases
+	Listener
+	Log
+	Operations
+	Overlays
+	SASL
+	Statistics
+	Threads
+	Time
+	TLS
+	Read/Write Waiters
+
+
+
+BACKENDS SUBSYSTEMS
+
+The main entry contains the type of backends enabled at compile time;
+the subentries, for each backend, contain the type of the backend.
+It should also contain the modules that have been loaded if dynamic 
+backends are enabled.
+
+
+
+CONNECTIONS
+
+The main entry is empty; it should contain some statistics on the number 
+of connections.
+Dynamic subentries are created for each open connection, with stats on
+the activity on that connection (the format will be detailed later).
+There are two special subentries that show the number of total and
+current connections respectively.
+
+
+
+DATABASES SUBSYSTEM
+
+The main entry contains the naming context of each configured database; 
+the subentries contain, for each database, the type and the naming
+context.
+
+
+
+LISTENER SUBSYSTEM
+
+It contains the description of the devices the server is currently 
+listening on
+
+
+
+LOG SUBSYSTEM
+
+It contains the currently active log items.  The "Log" subsystem allows 
+user modify operations on the "description" attribute, whose values MUST 
+be in the list of admittable log switches:
+
+	Trace
+	Packets
+	Args
+	Conns
+	BER
+	Filter
+	Config		(useless)
+	ACL
+	Stats
+	Stats2
+	Shell
+	Parse
+	Cache		(deprecated)
+	Index
+
+These values can be added, replaced or deleted; they affect what 
+messages are sent to the syslog device.
+
+
+
+OPERATIONS SUBSYSTEM
+
+It shows some statistics on the operations performed by the server:
+
+	Initiated
+	Completed
+
+and for each operation type, i.e.:
+
+	Bind
+        Unbind
+        Add
+        Delete
+        Modrdn
+        Modify
+        Compare
+        Search
+        Abandon
+        Extended
+
+
+
+OVERLAYS SUBSYSTEM
+
+The main entry contains the type of overlays available at run-time;
+the subentries, for each overlay, contain the type of the overlay.
+It should also contain the modules that have been loaded if dynamic 
+overlays are enabled.
+
+
+
+SASL
+
+Currently empty.
+
+
+
+STATISTICS SUBSYSTEM
+
+It shows some statistics on the data sent by the server:
+
+	Bytes
+	PDU
+	Entries
+	Referrals
+
+
+
+THREADS SUBSYSTEM
+
+It contains the maximum number of threads enabled at startup and the 
+current backload.
+
+
+
+TIME SUBSYSTEM
+
+It contains two subentries with the start time and the current time 
+of the server.
+
+
+
+TLS
+
+Currently empty.
+
+
+
+READ/WRITE WAITERS SUBSYSTEM
+
+It contains the number of current read waiters.
+
+
+
+NOTES
+
+This document is in a very early stage of maturity and will 
+probably be rewritten many times before the monitor backend is released.
+
+
+
+AUTHOR:	Pierangelo Masarati <ando@OpenLDAP.org>
+
diff --git a/servers/slapd/back-monitor/back-monitor.h b/servers/slapd/back-monitor/back-monitor.h
new file mode 100644
index 0000000..27966d7
--- /dev/null
+++ b/servers/slapd/back-monitor/back-monitor.h
@@ -0,0 +1,334 @@
+/* back-monitor.h - ldap monitor back-end header file */
+/* $OpenLDAP$ */
+/* This work is part of OpenLDAP Software <http://www.openldap.org/>.
+ *
+ * Copyright 2001-2022 The OpenLDAP Foundation.
+ * Portions Copyright 2001-2003 Pierangelo Masarati.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted only as authorized by the OpenLDAP
+ * Public License.
+ *
+ * A copy of this license is available in file LICENSE in the
+ * top-level directory of the distribution or, alternatively, at
+ * <http://www.OpenLDAP.org/license.html>.
+ */
+/* ACKNOWLEDGEMENTS:
+ * This work was initially developed by Pierangelo Masarati for inclusion
+ * in OpenLDAP Software.
+ */
+
+#ifndef _BACK_MONITOR_H_
+#define _BACK_MONITOR_H_
+
+#include <ldap_pvt.h>
+#include <ldap_pvt_thread.h>
+#include <ldap_avl.h>
+#include <slap.h>
+
+LDAP_BEGIN_DECL
+
+/* define if si_ad_labeledURI is removed from slap_schema */
+#undef MONITOR_DEFINE_LABELEDURI
+
+typedef struct monitor_callback_t {
+	int				(*mc_update)( Operation *op, SlapReply *rs, Entry *e, void *priv );
+						/* update callback
+						   for user-defined entries */
+	int				(*mc_modify)( Operation *op, SlapReply *rs, Entry *e, void *priv );
+						/* modify callback
+						   for user-defined entries */
+	int				(*mc_free)( Entry *e, void **priv );
+						/* delete callback
+						   for user-defined entries */
+	void				(*mc_dispose)( void **priv );
+						/* dispose callback
+						   to dispose of the callback
+						   private data itself */
+	void				*mc_private;	/* opaque pointer to
+						   private data */
+	struct monitor_callback_t	*mc_next;
+} monitor_callback_t;
+
+
+typedef struct monitor_entry_t {
+	ldap_pvt_thread_mutex_t	mp_mutex;	/* entry mutex */
+	Entry			*mp_next;	/* pointer to next sibling */
+	Entry			*mp_children;	/* pointer to first child */
+	Entry			*mp_last;	/* pointer to last child */
+	struct monitor_subsys_t	*mp_info;	/* subsystem info */
+#define mp_type		mp_info->mss_type
+	unsigned long		mp_flags;	/* flags */
+
+#define	MONITOR_F_NONE		0x0000U
+#define MONITOR_F_SUB		0x0001U		/* subentry of subsystem */
+#define MONITOR_F_PERSISTENT	0x0010U		/* persistent entry */
+#define MONITOR_F_PERSISTENT_CH	0x0020U		/* subsystem generates 
+						   persistent entries */
+#define MONITOR_F_VOLATILE	0x0040U		/* volatile entry */
+#define MONITOR_F_VOLATILE_CH	0x0080U		/* subsystem generates 
+						   volatile entries */
+#define MONITOR_F_EXTERNAL	0x0100U		/* externally added - don't free */
+/* NOTE: flags with 0xF0000000U mask are reserved for subsystem internals */
+
+	struct monitor_callback_t	*mp_cb;		/* callback sequence */
+	void		*mp_private;
+} monitor_entry_t;
+
+struct entry_limbo_t;			/* in init.c */
+
+typedef struct monitor_info_t {
+
+	/*
+	 * Internal data
+	 *
+	 * Lock order:
+	 * - cache first, then entry
+	 * - DIT in preorder DFS
+	 */
+	Avlnode			*mi_cache;
+	ldap_pvt_thread_mutex_t	mi_cache_lock;
+
+	/*
+	 * Config parameters
+	 */
+	struct berval		mi_startTime;		/* don't free it! */
+	struct berval		mi_creatorsName;	/* don't free it! */
+	struct berval		mi_ncreatorsName;	/* don't free it! */
+
+	/*
+	 * Specific schema entities
+	 */
+	ObjectClass		*mi_oc_monitor;
+	ObjectClass		*mi_oc_monitorServer;
+	ObjectClass		*mi_oc_monitorContainer;
+	ObjectClass		*mi_oc_monitorCounterObject;
+	ObjectClass		*mi_oc_monitorOperation;
+	ObjectClass		*mi_oc_monitorConnection;
+	ObjectClass		*mi_oc_managedObject;
+	ObjectClass		*mi_oc_monitoredObject;
+
+	AttributeDescription	*mi_ad_monitoredInfo;
+	AttributeDescription	*mi_ad_managedInfo;
+	AttributeDescription	*mi_ad_monitorCounter;
+	AttributeDescription	*mi_ad_monitorOpCompleted;
+	AttributeDescription	*mi_ad_monitorOpInitiated;
+	AttributeDescription	*mi_ad_monitorConnectionNumber;
+	AttributeDescription	*mi_ad_monitorConnectionAuthzDN;
+	AttributeDescription	*mi_ad_monitorConnectionLocalAddress;
+	AttributeDescription	*mi_ad_monitorConnectionPeerAddress;
+	AttributeDescription	*mi_ad_monitorTimestamp;
+	AttributeDescription	*mi_ad_monitorOverlay;
+	AttributeDescription	*mi_ad_monitorConnectionProtocol;
+	AttributeDescription	*mi_ad_monitorConnectionOpsReceived;
+	AttributeDescription	*mi_ad_monitorConnectionOpsExecuting;
+	AttributeDescription	*mi_ad_monitorConnectionOpsPending;
+	AttributeDescription	*mi_ad_monitorConnectionOpsCompleted;
+	AttributeDescription	*mi_ad_monitorConnectionGet;
+	AttributeDescription	*mi_ad_monitorConnectionRead;
+	AttributeDescription	*mi_ad_monitorConnectionWrite;
+	AttributeDescription	*mi_ad_monitorConnectionMask;
+	AttributeDescription	*mi_ad_monitorConnectionListener;
+	AttributeDescription	*mi_ad_monitorConnectionPeerDomain;
+	AttributeDescription	*mi_ad_monitorConnectionStartTime;
+	AttributeDescription	*mi_ad_monitorConnectionActivityTime;
+	AttributeDescription	*mi_ad_monitorIsShadow;
+	AttributeDescription	*mi_ad_monitorUpdateRef;
+	AttributeDescription	*mi_ad_monitorRuntimeConfig;
+	AttributeDescription	*mi_ad_monitorSuperiorDN;
+	AttributeDescription	*mi_ad_monitorConnectionOpsAsync;
+	AttributeDescription	*mi_ad_monitorLogLevel;
+	AttributeDescription	*mi_ad_monitorDebugLevel;
+
+	/*
+	 * Generic description attribute
+	 */
+	AttributeDescription	*mi_ad_readOnly;
+	AttributeDescription	*mi_ad_restrictedOperation;
+
+	struct entry_limbo_t	*mi_entry_limbo;
+} monitor_info_t;
+
+/*
+ * DNs
+ */
+
+enum {
+	SLAPD_MONITOR_BACKEND = 0,
+	SLAPD_MONITOR_CONN,
+	SLAPD_MONITOR_DATABASE,
+	SLAPD_MONITOR_LISTENER,
+	SLAPD_MONITOR_LOG,
+	SLAPD_MONITOR_OPS,
+	SLAPD_MONITOR_OVERLAY,
+	SLAPD_MONITOR_SASL,
+	SLAPD_MONITOR_SENT,
+	SLAPD_MONITOR_THREAD,
+	SLAPD_MONITOR_TIME,
+	SLAPD_MONITOR_TLS,
+	SLAPD_MONITOR_RWW,
+
+	SLAPD_MONITOR_LAST
+};
+
+#define SLAPD_MONITOR_AT		"cn"
+
+#define SLAPD_MONITOR_BACKEND_NAME	"Backends"
+#define SLAPD_MONITOR_BACKEND_RDN	\
+	SLAPD_MONITOR_AT "=" SLAPD_MONITOR_BACKEND_NAME
+#define SLAPD_MONITOR_BACKEND_DN	\
+	SLAPD_MONITOR_BACKEND_RDN "," SLAPD_MONITOR_DN
+
+#define SLAPD_MONITOR_CONN_NAME		"Connections"
+#define SLAPD_MONITOR_CONN_RDN	\
+	SLAPD_MONITOR_AT "=" SLAPD_MONITOR_CONN_NAME
+#define SLAPD_MONITOR_CONN_DN	\
+	SLAPD_MONITOR_CONN_RDN "," SLAPD_MONITOR_DN
+
+#define SLAPD_MONITOR_DATABASE_NAME	"Databases"
+#define SLAPD_MONITOR_DATABASE_RDN	\
+	SLAPD_MONITOR_AT "=" SLAPD_MONITOR_DATABASE_NAME
+#define SLAPD_MONITOR_DATABASE_DN	\
+	SLAPD_MONITOR_DATABASE_RDN "," SLAPD_MONITOR_DN
+
+#define SLAPD_MONITOR_LISTENER_NAME	"Listeners"
+#define SLAPD_MONITOR_LISTENER_RDN	\
+	SLAPD_MONITOR_AT "=" SLAPD_MONITOR_LISTENER_NAME
+#define SLAPD_MONITOR_LISTENER_DN	\
+	SLAPD_MONITOR_LISTENER_RDN "," SLAPD_MONITOR_DN
+
+#define SLAPD_MONITOR_LOG_NAME		"Log"
+#define SLAPD_MONITOR_LOG_RDN	\
+	SLAPD_MONITOR_AT "=" SLAPD_MONITOR_LOG_NAME
+#define SLAPD_MONITOR_LOG_DN	\
+	SLAPD_MONITOR_LOG_RDN "," SLAPD_MONITOR_DN
+
+#define SLAPD_MONITOR_OPS_NAME		"Operations"
+#define SLAPD_MONITOR_OPS_RDN	\
+	SLAPD_MONITOR_AT "=" SLAPD_MONITOR_OPS_NAME
+#define SLAPD_MONITOR_OPS_DN	\
+	SLAPD_MONITOR_OPS_RDN "," SLAPD_MONITOR_DN
+
+#define SLAPD_MONITOR_OVERLAY_NAME	"Overlays"
+#define SLAPD_MONITOR_OVERLAY_RDN  \
+	SLAPD_MONITOR_AT "=" SLAPD_MONITOR_OVERLAY_NAME
+#define SLAPD_MONITOR_OVERLAY_DN   \
+	SLAPD_MONITOR_OVERLAY_RDN "," SLAPD_MONITOR_DN
+
+#define SLAPD_MONITOR_SASL_NAME		"SASL"
+#define SLAPD_MONITOR_SASL_RDN	\
+	SLAPD_MONITOR_AT "=" SLAPD_MONITOR_SASL_NAME
+#define SLAPD_MONITOR_SASL_DN	\
+	SLAPD_MONITOR_SASL_RDN "," SLAPD_MONITOR_DN
+
+#define SLAPD_MONITOR_SENT_NAME		"Statistics"
+#define SLAPD_MONITOR_SENT_RDN	\
+	SLAPD_MONITOR_AT "=" SLAPD_MONITOR_SENT_NAME
+#define SLAPD_MONITOR_SENT_DN	\
+	SLAPD_MONITOR_SENT_RDN "," SLAPD_MONITOR_DN
+
+#define SLAPD_MONITOR_THREAD_NAME	"Threads"
+#define SLAPD_MONITOR_THREAD_RDN	\
+	SLAPD_MONITOR_AT "=" SLAPD_MONITOR_THREAD_NAME
+#define SLAPD_MONITOR_THREAD_DN	\
+	SLAPD_MONITOR_THREAD_RDN "," SLAPD_MONITOR_DN
+
+#define SLAPD_MONITOR_TIME_NAME		"Time"
+#define SLAPD_MONITOR_TIME_RDN  \
+	SLAPD_MONITOR_AT "=" SLAPD_MONITOR_TIME_NAME
+#define SLAPD_MONITOR_TIME_DN   \
+	SLAPD_MONITOR_TIME_RDN "," SLAPD_MONITOR_DN
+
+#define SLAPD_MONITOR_TLS_NAME		"TLS"
+#define SLAPD_MONITOR_TLS_RDN	\
+	SLAPD_MONITOR_AT "=" SLAPD_MONITOR_TLS_NAME
+#define SLAPD_MONITOR_TLS_DN	\
+	SLAPD_MONITOR_TLS_RDN "," SLAPD_MONITOR_DN
+
+#define SLAPD_MONITOR_RWW_NAME		"Waiters"
+#define SLAPD_MONITOR_RWW_RDN	\
+	SLAPD_MONITOR_AT "=" SLAPD_MONITOR_RWW_NAME
+#define SLAPD_MONITOR_RWW_DN	\
+	SLAPD_MONITOR_RWW_RDN "," SLAPD_MONITOR_DN
+
+typedef struct monitor_subsys_t {
+	char		*mss_name;
+	struct berval	mss_rdn;
+	struct berval	mss_dn;
+	struct berval	mss_ndn;
+	struct berval	mss_desc[ 3 ];
+	int		mss_flags;
+#define MONITOR_F_OPENED	0x10000000U
+
+#define MONITOR_HAS_VOLATILE_CH( mp ) \
+	( ( mp )->mp_flags & MONITOR_F_VOLATILE_CH )
+#define MONITOR_HAS_CHILDREN( mp ) \
+	( ( mp )->mp_children || MONITOR_HAS_VOLATILE_CH( mp ) )
+
+	/* initialize entry and subentries */
+	int		( *mss_open )( BackendDB *, struct monitor_subsys_t *ms );
+	/* destroy structure */
+	int		( *mss_destroy )( BackendDB *, struct monitor_subsys_t *ms );
+	/* update existing dynamic entry and subentries */
+	int		( *mss_update )( Operation *, SlapReply *, Entry * );
+	/* create new dynamic subentries */
+	int		( *mss_create )( Operation *, SlapReply *,
+				struct berval *ndn, Entry *, Entry ** );
+	/* modify entry and subentries */
+	int		( *mss_modify )( Operation *, SlapReply *, Entry * );
+
+	void		*mss_private;
+} monitor_subsys_t;
+
+extern BackendDB *be_monitor;
+
+/* increase this bufsize if entries in string form get too big */
+#define BACKMONITOR_BUFSIZE	8192
+
+typedef int (monitor_cbfunc)( struct berval *ndn, monitor_callback_t *cb,
+	struct berval *base, int scope, struct berval *filter );
+
+typedef int (monitor_cbafunc)( struct berval *ndn, Attribute *a,
+	monitor_callback_t *cb,
+	struct berval *base, int scope, struct berval *filter );
+
+typedef struct monitor_extra_t {
+	int (*is_configured)(void);
+	monitor_subsys_t * (*get_subsys)( const char *name );
+	monitor_subsys_t * (*get_subsys_by_dn)( struct berval *ndn, int sub );
+
+	int (*register_subsys)( monitor_subsys_t *ms );
+	int (*register_backend)( BackendInfo *bi );
+	int (*register_database)( BackendDB *be, struct berval *ndn_out );
+	int (*register_overlay_info)( slap_overinst *on );
+	int (*register_overlay)( BackendDB *be, slap_overinst *on, struct berval *ndn_out );
+	int (*register_entry)( Entry *e, monitor_callback_t *cb,
+		monitor_subsys_t *ms, unsigned long flags );
+	int (*register_entry_parent)( Entry *e, monitor_callback_t *cb,
+		monitor_subsys_t *ms, unsigned long flags,
+		struct berval *base, int scope, struct berval *filter );
+	monitor_cbafunc *register_entry_attrs;
+	monitor_cbfunc *register_entry_callback;
+
+	int (*unregister_entry)( struct berval *ndn );
+	monitor_cbfunc *unregister_entry_parent;
+	monitor_cbafunc *unregister_entry_attrs;
+	monitor_cbfunc *unregister_entry_callback;
+	Entry * (*entry_stub)( struct berval *pdn,
+		struct berval *pndn,
+		struct berval *rdn,
+		ObjectClass *oc,
+		struct berval *create,
+		struct berval *modify );
+	monitor_entry_t * (*entrypriv_create)( void );
+	int (*register_subsys_late)( monitor_subsys_t *ms );
+	Entry * (*entry_get_unlocked)( struct berval *ndn );
+} monitor_extra_t;
+
+LDAP_END_DECL
+
+#include "proto-back-monitor.h"
+
+#endif /* _back_monitor_h_ */
+
diff --git a/servers/slapd/back-monitor/backend.c b/servers/slapd/back-monitor/backend.c
new file mode 100644
index 0000000..d3afdf1
--- /dev/null
+++ b/servers/slapd/back-monitor/backend.c
@@ -0,0 +1,152 @@
+/* backend.c - deals with backend subsystem */
+/* $OpenLDAP$ */
+/* This work is part of OpenLDAP Software <http://www.openldap.org/>.
+ *
+ * Copyright 2001-2022 The OpenLDAP Foundation.
+ * Portions Copyright 2001-2003 Pierangelo Masarati.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted only as authorized by the OpenLDAP
+ * Public License.
+ *
+ * A copy of this license is available in file LICENSE in the
+ * top-level directory of the distribution or, alternatively, at
+ * <http://www.OpenLDAP.org/license.html>.
+ */
+/* ACKNOWLEDGEMENTS:
+ * This work was initially developed by Pierangelo Masarati for inclusion
+ * in OpenLDAP Software.
+ */
+
+
+#include "portable.h"
+
+#include <stdio.h>
+#include <ac/string.h>
+
+#include "slap.h"
+#include "back-monitor.h"
+
+/*
+ * initializes backend subentries
+ */
+int
+monitor_subsys_backend_init(
+	BackendDB		*be,
+	monitor_subsys_t	*ms
+)
+{
+	monitor_info_t		*mi;
+	Entry			*e_backend;
+	int			i;
+	monitor_entry_t		*mp;
+	monitor_subsys_t	*ms_database;
+	BackendInfo			*bi;
+
+	mi = ( monitor_info_t * )be->be_private;
+
+	ms_database = monitor_back_get_subsys( SLAPD_MONITOR_DATABASE_NAME );
+	if ( ms_database == NULL ) {
+		Debug( LDAP_DEBUG_ANY,
+			"monitor_subsys_backend_init: "
+			"unable to get "
+			"\"" SLAPD_MONITOR_DATABASE_NAME "\" "
+			"subsystem\n" );
+		return -1;
+	}
+
+	if ( monitor_cache_get( mi, &ms->mss_ndn, &e_backend ) ) {
+		Debug( LDAP_DEBUG_ANY,
+			"monitor_subsys_backend_init: "
+			"unable to get entry \"%s\"\n",
+			ms->mss_ndn.bv_val );
+		return( -1 );
+	}
+
+	i = -1;
+	LDAP_STAILQ_FOREACH( bi, &backendInfo, bi_next ) {
+		char 		buf[ BACKMONITOR_BUFSIZE ];
+		BackendDB	*be;
+		struct berval 	bv;
+		int		j;
+		Entry		*e;
+
+		i++;
+
+		bv.bv_len = snprintf( buf, sizeof( buf ), "cn=Backend %d", i );
+		bv.bv_val = buf;
+
+		e = monitor_entry_stub( &ms->mss_dn, &ms->mss_ndn, &bv,
+			mi->mi_oc_monitoredObject, NULL, NULL );
+
+		if ( e == NULL ) {
+			Debug( LDAP_DEBUG_ANY,
+				"monitor_subsys_backend_init: "
+				"unable to create entry \"cn=Backend %d,%s\"\n",
+				i, ms->mss_ndn.bv_val );
+			return( -1 );
+		}
+		
+		ber_str2bv( bi->bi_type, 0, 0, &bv );
+		attr_merge_normalize_one( e, mi->mi_ad_monitoredInfo,
+				&bv, NULL );
+		attr_merge_normalize_one( e_backend, mi->mi_ad_monitoredInfo,
+				&bv, NULL );
+
+		attr_merge_normalize_one( e, mi->mi_ad_monitorRuntimeConfig,
+			bi->bi_cf_ocs == NULL ? (struct berval *)&slap_false_bv :
+				(struct berval *)&slap_true_bv, NULL );
+
+		if ( bi->bi_controls ) {
+			int j;
+
+			for ( j = 0; bi->bi_controls[ j ]; j++ ) {
+				ber_str2bv( bi->bi_controls[ j ], 0, 0, &bv );
+				attr_merge_one( e, slap_schema.si_ad_supportedControl,
+						&bv, &bv );
+			}
+		}
+
+		j = -1;
+		LDAP_STAILQ_FOREACH( be, &backendDB, be_next ) {
+			char		buf[ SLAP_LDAPDN_MAXLEN ];
+			struct berval	dn;
+			
+			j++;
+
+			if ( be->bd_info != bi ) {
+				continue;
+			}
+
+			snprintf( buf, sizeof( buf ), "cn=Database %d,%s",
+					j, ms_database->mss_dn.bv_val );
+
+			ber_str2bv( buf, 0, 0, &dn );
+			attr_merge_normalize_one( e, slap_schema.si_ad_seeAlso,
+					&dn, NULL );
+		}
+		
+		mp = monitor_entrypriv_create();
+		if ( mp == NULL ) {
+			return -1;
+		}
+		e->e_private = ( void * )mp;
+		mp->mp_info = ms;
+		mp->mp_flags = ms->mss_flags | MONITOR_F_SUB;
+
+		if ( monitor_cache_add( mi, e, e_backend ) ) {
+			Debug( LDAP_DEBUG_ANY,
+				"monitor_subsys_backend_init: "
+				"unable to add entry \"cn=Backend %d,%s\"\n",
+				i,
+					ms->mss_ndn.bv_val );
+			return( -1 );
+		}
+	}
+	
+	monitor_cache_release( mi, e_backend );
+
+	return( 0 );
+}
+
diff --git a/servers/slapd/back-monitor/bind.c b/servers/slapd/back-monitor/bind.c
new file mode 100644
index 0000000..718c001
--- /dev/null
+++ b/servers/slapd/back-monitor/bind.c
@@ -0,0 +1,48 @@
+/* bind.c - monitor backend bind routine */
+/* $OpenLDAP$ */
+/* This work is part of OpenLDAP Software <http://www.openldap.org/>.
+ *
+ * Copyright 2001-2022 The OpenLDAP Foundation.
+ * Portions Copyright 2001-2003 Pierangelo Masarati.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted only as authorized by the OpenLDAP
+ * Public License.
+ *
+ * A copy of this license is available in file LICENSE in the
+ * top-level directory of the distribution or, alternatively, at
+ * <http://www.OpenLDAP.org/license.html>.
+ */
+/* ACKNOWLEDGEMENTS:
+ * This work was initially developed by Pierangelo Masarati for inclusion
+ * in OpenLDAP Software.
+ */
+
+#include "portable.h"
+
+#include <stdio.h>
+
+#include <slap.h>
+#include "back-monitor.h"
+
+/*
+ * At present, only rootdn can bind with simple bind
+ */
+
+int
+monitor_back_bind( Operation *op, SlapReply *rs )
+{
+	Debug(LDAP_DEBUG_ARGS, "==> monitor_back_bind: dn: %s\n", 
+			op->o_req_dn.bv_val );
+
+	if ( be_isroot_pw( op ) ) {
+		return LDAP_SUCCESS;
+	}
+
+	rs->sr_err = LDAP_INVALID_CREDENTIALS;
+	send_ldap_result( op, rs );
+
+	return rs->sr_err;
+}
+
diff --git a/servers/slapd/back-monitor/cache.c b/servers/slapd/back-monitor/cache.c
new file mode 100644
index 0000000..990c88e
--- /dev/null
+++ b/servers/slapd/back-monitor/cache.c
@@ -0,0 +1,486 @@
+/* cache.c - routines to maintain an in-core cache of entries */
+/* $OpenLDAP$ */
+/* This work is part of OpenLDAP Software <http://www.openldap.org/>.
+ *
+ * Copyright 2001-2022 The OpenLDAP Foundation.
+ * Portions Copyright 2001-2003 Pierangelo Masarati.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted only as authorized by the OpenLDAP
+ * Public License.
+ *
+ * A copy of this license is available in file LICENSE in the
+ * top-level directory of the distribution or, alternatively, at
+ * <http://www.OpenLDAP.org/license.html>.
+ */
+/* ACKNOWLEDGEMENTS:
+ * This work was initially developed by Pierangelo Masarati for inclusion
+ * in OpenLDAP Software.
+ */
+
+#include "portable.h"
+
+#include <stdio.h>
+#include "ac/string.h"
+
+#include "slap.h"
+
+#include "back-monitor.h"
+
+/*
+ * The cache maps DNs to Entries.
+ * Each entry, on turn, holds the list of its children in the e_private field.
+ * This is used by search operation to perform onelevel and subtree candidate
+ * selection.
+ */
+typedef struct monitor_cache_t {
+	struct berval		mc_ndn;
+	Entry   		*mc_e;
+} monitor_cache_t;
+
+/*
+ * compares entries based on the dn
+ */
+int
+monitor_cache_cmp(
+	const void	*c1,
+	const void	*c2 )
+{
+	monitor_cache_t 	*cc1 = ( monitor_cache_t * )c1;
+	monitor_cache_t 	*cc2 = ( monitor_cache_t * )c2;
+
+	/*
+	 * case sensitive, because the dn MUST be normalized
+	 */
+	return ber_bvcmp( &cc1->mc_ndn, &cc2->mc_ndn );
+}
+
+/*
+ * checks for duplicate entries
+ */
+int
+monitor_cache_dup(
+	void		*c1,
+	void		*c2 )
+{
+	monitor_cache_t *cc1 = ( monitor_cache_t * )c1;
+	monitor_cache_t *cc2 = ( monitor_cache_t * )c2;
+
+	/*
+	 * case sensitive, because the dn MUST be normalized
+	 */
+	return ber_bvcmp( &cc1->mc_ndn, &cc2->mc_ndn ) == 0 ? -1 : 0;
+}
+
+/*
+ * adds an entry to the cache and inits the mutex
+ */
+int
+monitor_cache_add(
+	monitor_info_t	*mi,
+	Entry		*e,
+	Entry		*parent )
+{
+	monitor_cache_t tmp_mc, *mc, *pmc = NULL;
+	Entry **ep = NULL, *prev = NULL;
+	int		rc = -1;
+
+	assert( mi != NULL );
+	assert( e != NULL );
+
+	dnParent( &e->e_nname, &tmp_mc.mc_ndn );
+
+	mc = ( monitor_cache_t * )ch_malloc( sizeof( monitor_cache_t ) );
+	mc->mc_ndn = e->e_nname;
+	mc->mc_e = e;
+
+	if ( parent ) {
+		/* Shortcut, but follow lock order as a fallback */
+		if ( ldap_pvt_thread_mutex_trylock( &mi->mi_cache_lock ) ) {
+			monitor_cache_release( mi, parent );
+			ldap_pvt_thread_mutex_lock( &mi->mi_cache_lock );
+			monitor_cache_lock( parent );
+		}
+	} else {
+		ldap_pvt_thread_mutex_lock( &mi->mi_cache_lock );
+	}
+
+	/* Allow database root be added */
+	if ( parent == NULL && mi->mi_cache != NULL ) {
+		pmc = ldap_avl_find( mi->mi_cache, &tmp_mc, monitor_cache_cmp );
+		if ( pmc == NULL ) {
+			goto done;
+		}
+		parent = pmc->mc_e;
+		monitor_cache_lock( parent );
+	}
+
+	rc = ldap_avl_insert( &mi->mi_cache, mc,
+			monitor_cache_cmp, monitor_cache_dup );
+	if ( rc != LDAP_SUCCESS ) {
+		goto done;
+	}
+
+	if ( parent != NULL ) {
+		monitor_entry_t *mp = parent->e_private;
+
+		if ( mp->mp_children ) {
+			monitor_entry_t *tail;
+
+			monitor_cache_lock( mp->mp_last );
+			tail = mp->mp_last->e_private;
+			tail->mp_next = e;
+			monitor_cache_release( mi, mp->mp_last );
+			mp->mp_last = e;
+		} else {
+			mp->mp_children = mp->mp_last = e;
+		}
+	}
+
+done:
+	if ( pmc != NULL ) {
+		monitor_cache_release( mi, parent );
+	}
+	ldap_pvt_thread_mutex_unlock( &mi->mi_cache_lock );
+
+	if ( rc != LDAP_SUCCESS ) {
+		ch_free( mc );
+	}
+	return rc;
+}
+
+/*
+ * locks the entry (no r/w)
+ */
+int
+monitor_cache_lock(
+	Entry		*e )
+{
+	monitor_entry_t *mp;
+
+	assert( e != NULL );
+	assert( e->e_private != NULL );
+
+	mp = ( monitor_entry_t * )e->e_private;
+	ldap_pvt_thread_mutex_lock( &mp->mp_mutex );
+
+	return( 0 );
+}
+
+/*
+ * tries to lock the entry (no r/w)
+ */
+int
+monitor_cache_trylock(
+	Entry		*e )
+{
+	monitor_entry_t *mp;
+
+	assert( e != NULL );
+	assert( e->e_private != NULL );
+
+	mp = ( monitor_entry_t * )e->e_private;
+	return ldap_pvt_thread_mutex_trylock( &mp->mp_mutex );
+}
+
+/*
+ * gets an entry from the cache based on the normalized dn 
+ * with mutex locked
+ */
+int
+monitor_cache_get(
+	monitor_info_t	*mi,
+	struct berval	*ndn,
+	Entry		**ep )
+{
+	monitor_cache_t tmp_mc, *mc;
+
+	assert( mi != NULL );
+	assert( ndn != NULL );
+	assert( ep != NULL );
+
+	*ep = NULL;
+
+	tmp_mc.mc_ndn = *ndn;
+
+	ldap_pvt_thread_mutex_lock( &mi->mi_cache_lock );
+	mc = ( monitor_cache_t * )ldap_avl_find( mi->mi_cache,
+			( caddr_t )&tmp_mc, monitor_cache_cmp );
+
+	if ( mc != NULL ) {
+		/* entry is returned with mutex locked */
+		monitor_cache_lock( mc->mc_e );
+		*ep = mc->mc_e;
+	}
+
+	ldap_pvt_thread_mutex_unlock( &mi->mi_cache_lock );
+
+	return ( *ep == NULL ? -1 : 0 );
+}
+
+/*
+ * gets an entry from the cache based on the normalized dn 
+ * with mutex locked
+ */
+int
+monitor_cache_remove(
+	monitor_info_t	*mi,
+	struct berval	*ndn,
+	Entry		**ep )
+{
+	monitor_cache_t tmp_mc, *mc;
+	struct berval	pndn;
+
+	assert( mi != NULL );
+	assert( ndn != NULL );
+	assert( ep != NULL );
+
+	*ep = NULL;
+
+	dnParent( ndn, &pndn );
+
+retry:;
+	ldap_pvt_thread_mutex_lock( &mi->mi_cache_lock );
+
+	tmp_mc.mc_ndn = *ndn;
+	mc = ( monitor_cache_t * )ldap_avl_find( mi->mi_cache,
+			( caddr_t )&tmp_mc, monitor_cache_cmp );
+
+	if ( mc != NULL ) {
+		monitor_cache_t *pmc;
+
+		tmp_mc.mc_ndn = pndn;
+		pmc = ( monitor_cache_t * )ldap_avl_find( mi->mi_cache,
+			( caddr_t )&tmp_mc, monitor_cache_cmp );
+		if ( pmc != NULL ) {
+			monitor_entry_t	*mp = (monitor_entry_t *)mc->mc_e->e_private,
+					*pmp = (monitor_entry_t *)pmc->mc_e->e_private;
+			Entry		**entryp, *prev = NULL;
+
+			monitor_cache_lock( pmc->mc_e );
+
+			for ( entryp = &pmp->mp_children; *entryp != NULL;  ) {
+				monitor_entry_t	*next = (monitor_entry_t *)(*entryp)->e_private;
+
+				monitor_cache_lock( *entryp );
+				if ( next == mp ) {
+					if ( mc->mc_e == pmp->mp_last ) {
+						pmp->mp_last = prev;
+					}
+					*entryp = next->mp_next;
+					entryp = NULL;
+					break;
+				}
+
+				if ( prev != NULL ) {
+					monitor_cache_release( mi, prev );
+				}
+				prev = *entryp;
+				entryp = &next->mp_next;
+			}
+			if ( prev ) {
+				monitor_cache_release( mi, prev );
+			}
+
+			if ( entryp != NULL ) {
+				Debug( LDAP_DEBUG_ANY,
+					"monitor_cache_remove(\"%s\"): "
+					"not in parent's list\n",
+					ndn->bv_val );
+			}
+
+			/* either succeeded, and the entry is no longer
+			 * in its parent's list, or failed, and the
+			 * entry is neither mucked with nor returned */
+			monitor_cache_release( mi, pmc->mc_e );
+
+			if ( entryp == NULL ) {
+				monitor_cache_t *tmpmc;
+
+				tmp_mc.mc_ndn = *ndn;
+				tmpmc = ldap_avl_delete( &mi->mi_cache,
+					( caddr_t )&tmp_mc, monitor_cache_cmp );
+				assert( tmpmc == mc );
+
+				*ep = mc->mc_e;
+				ch_free( mc );
+				mc = NULL;
+
+				/* NOTE: we destroy the mutex, but otherwise
+				 * leave the private data around; specifically,
+				 * callbacks need be freed by someone else */
+
+				ldap_pvt_thread_mutex_destroy( &mp->mp_mutex );
+				mp->mp_next = NULL;
+				mp->mp_children = NULL;
+				mp->mp_last = NULL;
+			}
+
+		}
+
+		if ( mc ) {
+			monitor_cache_release( mi, mc->mc_e );
+		}
+	}
+
+	ldap_pvt_thread_mutex_unlock( &mi->mi_cache_lock );
+
+	return ( *ep == NULL ? -1 : 0 );
+}
+
+/*
+ * If the entry exists in cache, it is returned in locked status;
+ * otherwise, if the parent exists, if it may generate volatile 
+ * descendants an attempt to generate the required entry is
+ * performed and, if successful, the entry is returned
+ */
+int
+monitor_cache_dn2entry(
+	Operation		*op,
+	SlapReply		*rs,
+	struct berval		*ndn,
+	Entry			**ep,
+	Entry			**matched )
+{
+	monitor_info_t *mi = (monitor_info_t *)op->o_bd->be_private;
+	int 			rc;
+	struct berval		p_ndn = BER_BVNULL;
+	Entry 			*e_parent;
+	monitor_entry_t 	*mp;
+		
+	assert( mi != NULL );
+	assert( ndn != NULL );
+	assert( ep != NULL );
+	assert( matched != NULL );
+
+	*matched = NULL;
+
+	if ( !dnIsSuffix( ndn, &op->o_bd->be_nsuffix[ 0 ] ) ) {
+		return( -1 );
+	}
+
+	rc = monitor_cache_get( mi, ndn, ep );
+       	if ( !rc && *ep != NULL ) {
+		return( 0 );
+	}
+
+	/* try with parent/ancestors */
+	if ( BER_BVISNULL( ndn ) ) {
+		BER_BVSTR( &p_ndn, "" );
+
+	} else {
+		dnParent( ndn, &p_ndn );
+	}
+
+	rc = monitor_cache_dn2entry( op, rs, &p_ndn, &e_parent, matched );
+	if ( rc || e_parent == NULL ) {
+		return( -1 );
+	}
+
+	mp = ( monitor_entry_t * )e_parent->e_private;
+	rc = -1;
+	if ( mp->mp_flags & MONITOR_F_VOLATILE_CH ) {
+		/* parent entry generates volatile children */
+		rc = monitor_entry_create( op, rs, ndn, e_parent, ep );
+	}
+
+	if ( !rc ) {
+		monitor_cache_lock( *ep );
+		monitor_cache_release( mi, e_parent );
+
+	} else {
+		*matched = e_parent;
+	}
+	
+	return( rc );
+}
+
+/*
+ * releases the lock of the entry; if it is marked as volatile, it is
+ * destroyed.
+ */
+int
+monitor_cache_release(
+	monitor_info_t	*mi,
+	Entry		*e )
+{
+	monitor_entry_t *mp;
+
+	assert( mi != NULL );
+	assert( e != NULL );
+	assert( e->e_private != NULL );
+	
+	mp = ( monitor_entry_t * )e->e_private;
+
+	if ( mp->mp_flags & MONITOR_F_VOLATILE ) {
+		ldap_pvt_thread_mutex_unlock( &mp->mp_mutex );
+		ldap_pvt_thread_mutex_destroy( &mp->mp_mutex );
+		ch_free( mp );
+		e->e_private = NULL;
+		entry_free( e );
+
+		return( 0 );
+	}
+	
+	ldap_pvt_thread_mutex_unlock( &mp->mp_mutex );
+
+	return( 0 );
+}
+
+static void
+monitor_entry_destroy( void *v_mc )
+{
+	monitor_cache_t		*mc = (monitor_cache_t *)v_mc;
+
+	if ( mc->mc_e != NULL ) {
+		monitor_entry_t *mp;
+
+		assert( mc->mc_e->e_private != NULL );
+	
+		mp = ( monitor_entry_t * )mc->mc_e->e_private;
+
+		if ( mp->mp_cb ) {
+			monitor_callback_t	*cb;
+
+			for ( cb = mp->mp_cb; cb != NULL; ) {
+				monitor_callback_t	*next = cb->mc_next;
+
+				if ( cb->mc_free ) {
+					(void)cb->mc_free( mc->mc_e, &cb->mc_private );
+				}
+				ch_free( mp->mp_cb );
+
+				cb = next;
+			}
+		}
+
+		ldap_pvt_thread_mutex_destroy( &mp->mp_mutex );
+
+		ch_free( mp );
+		mc->mc_e->e_private = NULL;
+		entry_free( mc->mc_e );
+	}
+
+	ch_free( mc );
+}
+
+int
+monitor_cache_destroy(
+	monitor_info_t	*mi )
+{
+	if ( mi->mi_cache ) {
+		ldap_avl_free( mi->mi_cache, monitor_entry_destroy );
+	}
+
+	return 0;
+}
+
+int monitor_back_release(
+	Operation *op,
+	Entry *e,
+	int rw )
+{
+	monitor_info_t	*mi = ( monitor_info_t * )op->o_bd->be_private;
+	return monitor_cache_release( mi, e );
+}
diff --git a/servers/slapd/back-monitor/compare.c b/servers/slapd/back-monitor/compare.c
new file mode 100644
index 0000000..e17b4f1
--- /dev/null
+++ b/servers/slapd/back-monitor/compare.c
@@ -0,0 +1,76 @@
+/* compare.c - monitor backend compare routine */
+/* $OpenLDAP$ */
+/* This work is part of OpenLDAP Software <http://www.openldap.org/>.
+ *
+ * Copyright 2001-2022 The OpenLDAP Foundation.
+ * Portions Copyright 2001-2003 Pierangelo Masarati.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted only as authorized by the OpenLDAP
+ * Public License.
+ *
+ * A copy of this license is available in file LICENSE in the
+ * top-level directory of the distribution or, alternatively, at
+ * <http://www.OpenLDAP.org/license.html>.
+ */
+/* ACKNOWLEDGEMENTS:
+ * This work was initially developed by Pierangelo Masarati for inclusion
+ * in OpenLDAP Software.
+ */
+
+#include "portable.h"
+
+#include <stdio.h>
+
+#include <slap.h>
+#include "back-monitor.h"
+
+int
+monitor_back_compare( Operation *op, SlapReply *rs )
+{
+	monitor_info_t	*mi = ( monitor_info_t * ) op->o_bd->be_private;
+	Entry           *e, *matched = NULL;
+	int		rc;
+
+	/* get entry with reader lock */
+	monitor_cache_dn2entry( op, rs, &op->o_req_ndn, &e, &matched );
+	if ( e == NULL ) {
+		rs->sr_err = LDAP_NO_SUCH_OBJECT;
+		if ( matched ) {
+			if ( !access_allowed_mask( op, matched,
+					slap_schema.si_ad_entry,
+					NULL, ACL_DISCLOSE, NULL, NULL ) )
+			{
+				/* do nothing */ ;
+			} else {
+				rs->sr_matched = matched->e_dn;
+			}
+		}
+		send_ldap_result( op, rs );
+		if ( matched ) {
+			monitor_cache_release( mi, matched );
+			rs->sr_matched = NULL;
+		}
+
+		return rs->sr_err;
+	}
+
+	monitor_entry_update( op, rs, e );
+	rs->sr_err = slap_compare_entry( op, e, op->orc_ava );
+	rc = rs->sr_err;
+	switch ( rc ) {
+	case LDAP_COMPARE_FALSE:
+	case LDAP_COMPARE_TRUE:
+		rc = LDAP_SUCCESS;
+		break;
+	}
+		
+	send_ldap_result( op, rs );
+	rs->sr_err = rc;
+
+	monitor_cache_release( mi, e );
+
+	return rs->sr_err;
+}
+
diff --git a/servers/slapd/back-monitor/conn.c b/servers/slapd/back-monitor/conn.c
new file mode 100644
index 0000000..adfb626
--- /dev/null
+++ b/servers/slapd/back-monitor/conn.c
@@ -0,0 +1,526 @@
+/* conn.c - deal with connection subsystem */
+/* $OpenLDAP$ */
+/* This work is part of OpenLDAP Software <http://www.openldap.org/>.
+ *
+ * Copyright 2001-2022 The OpenLDAP Foundation.
+ * Portions Copyright 2001-2003 Pierangelo Masarati.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted only as authorized by the OpenLDAP
+ * Public License.
+ *
+ * A copy of this license is available in file LICENSE in the
+ * top-level directory of the distribution or, alternatively, at
+ * <http://www.OpenLDAP.org/license.html>.
+ */
+/* ACKNOWLEDGEMENTS:
+ * This work was initially developed by Pierangelo Masarati for inclusion
+ * in OpenLDAP Software.
+ */
+
+#include "portable.h"
+
+#include <stdio.h>
+#include <ac/string.h>
+
+#include "slap.h"
+#include "lutil.h"
+#include "back-monitor.h"
+
+static int
+monitor_subsys_conn_update(
+	Operation		*op,
+	SlapReply		*rs,
+	Entry                   *e );
+
+static int 
+monitor_subsys_conn_create( 
+	Operation		*op,
+	SlapReply		*rs,
+	struct berval		*ndn,
+	Entry 			*e_parent,
+	Entry			**ep );
+
+int
+monitor_subsys_conn_init(
+	BackendDB		*be,
+	monitor_subsys_t	*ms )
+{
+	monitor_info_t	*mi;
+	Entry		*e, *e_conn;
+	monitor_entry_t	*mp;
+	char		buf[ BACKMONITOR_BUFSIZE ];
+	struct berval	bv;
+
+	assert( be != NULL );
+
+	ms->mss_update = monitor_subsys_conn_update;
+	ms->mss_create = monitor_subsys_conn_create;
+
+	mi = ( monitor_info_t * )be->be_private;
+
+	if ( monitor_cache_get( mi, &ms->mss_ndn, &e_conn ) ) {
+		Debug( LDAP_DEBUG_ANY,
+			"monitor_subsys_conn_init: "
+			"unable to get entry \"%s\"\n",
+			ms->mss_ndn.bv_val );
+		return( -1 );
+	}
+
+	mp = ( monitor_entry_t * )e_conn->e_private;
+
+	/*
+	 * Max file descriptors
+	 */
+	BER_BVSTR( &bv, "cn=Max File Descriptors" );
+	e = monitor_entry_stub( &ms->mss_dn, &ms->mss_ndn, &bv,
+		mi->mi_oc_monitorCounterObject, NULL, NULL );
+	
+	if ( e == NULL ) {
+		Debug( LDAP_DEBUG_ANY,
+			"monitor_subsys_conn_init: "
+			"unable to create entry \"%s,%s\"\n",
+			bv.bv_val, ms->mss_ndn.bv_val );
+		return( -1 );
+	}
+
+	if ( dtblsize ) {
+		bv.bv_val = buf;
+		bv.bv_len = snprintf( buf, sizeof( buf ), "%d", dtblsize );
+
+	} else {
+		BER_BVSTR( &bv, "0" );
+	}
+	attr_merge_one( e, mi->mi_ad_monitorCounter, &bv, NULL );
+	
+	mp = monitor_entrypriv_create();
+	if ( mp == NULL ) {
+		return -1;
+	}
+	e->e_private = ( void * )mp;
+	mp->mp_info = ms;
+	mp->mp_flags = ms->mss_flags \
+		| MONITOR_F_SUB | MONITOR_F_PERSISTENT;
+	mp->mp_flags &= ~MONITOR_F_VOLATILE_CH;
+
+	if ( monitor_cache_add( mi, e, e_conn ) ) {
+		Debug( LDAP_DEBUG_ANY,
+			"monitor_subsys_conn_init: "
+			"unable to add entry \"cn=Total,%s\"\n",
+			ms->mss_ndn.bv_val );
+		return( -1 );
+	}
+
+	/*
+	 * Total conns
+	 */
+	BER_BVSTR( &bv, "cn=Total" );
+	e = monitor_entry_stub( &ms->mss_dn, &ms->mss_ndn, &bv,
+		mi->mi_oc_monitorCounterObject, NULL, NULL );
+	
+	if ( e == NULL ) {
+		Debug( LDAP_DEBUG_ANY,
+			"monitor_subsys_conn_init: "
+			"unable to create entry \"cn=Total,%s\"\n",
+			ms->mss_ndn.bv_val );
+		return( -1 );
+	}
+	
+	BER_BVSTR( &bv, "-1" );
+	attr_merge_one( e, mi->mi_ad_monitorCounter, &bv, NULL );
+	
+	mp = monitor_entrypriv_create();
+	if ( mp == NULL ) {
+		return -1;
+	}
+	e->e_private = ( void * )mp;
+	mp->mp_info = ms;
+	mp->mp_flags = ms->mss_flags \
+		| MONITOR_F_SUB | MONITOR_F_PERSISTENT;
+	mp->mp_flags &= ~MONITOR_F_VOLATILE_CH;
+
+	if ( monitor_cache_add( mi, e, e_conn ) ) {
+		Debug( LDAP_DEBUG_ANY,
+			"monitor_subsys_conn_init: "
+			"unable to add entry \"cn=Total,%s\"\n",
+			ms->mss_ndn.bv_val );
+		return( -1 );
+	}
+
+	/*
+	 * Current conns
+	 */
+	BER_BVSTR( &bv, "cn=Current" );
+	e = monitor_entry_stub( &ms->mss_dn, &ms->mss_ndn, &bv,
+		mi->mi_oc_monitorCounterObject, NULL, NULL );
+
+	if ( e == NULL ) {
+		Debug( LDAP_DEBUG_ANY,
+			"monitor_subsys_conn_init: "
+			"unable to create entry \"cn=Current,%s\"\n",
+			ms->mss_ndn.bv_val );
+		return( -1 );
+	}
+	
+	BER_BVSTR( &bv, "0" );
+	attr_merge_one( e, mi->mi_ad_monitorCounter, &bv, NULL );
+	
+	mp = monitor_entrypriv_create();
+	if ( mp == NULL ) {
+		return -1;
+	}
+	e->e_private = ( void * )mp;
+	mp->mp_info = ms;
+	mp->mp_flags = ms->mss_flags \
+		| MONITOR_F_SUB | MONITOR_F_PERSISTENT;
+	mp->mp_flags &= ~MONITOR_F_VOLATILE_CH;
+
+	if ( monitor_cache_add( mi, e, e_conn ) ) {
+		Debug( LDAP_DEBUG_ANY,
+			"monitor_subsys_conn_init: "
+			"unable to add entry \"cn=Current,%s\"\n",
+			ms->mss_ndn.bv_val );
+		return( -1 );
+	}
+	
+	monitor_cache_release( mi, e_conn );
+
+	return( 0 );
+}
+
+static int
+monitor_subsys_conn_update(
+	Operation		*op,
+	SlapReply		*rs,
+	Entry                   *e )
+{
+	monitor_info_t	*mi = ( monitor_info_t * )op->o_bd->be_private;
+
+	long 			n = -1;
+	static struct berval	total_bv = BER_BVC( "cn=total" ),
+				current_bv = BER_BVC( "cn=current" );
+	struct berval		rdn;
+
+	assert( mi != NULL );
+	assert( e != NULL );
+
+	dnRdn( &e->e_nname, &rdn );
+	
+	if ( dn_match( &rdn, &total_bv ) ) {
+		n = connections_nextid() - SLAPD_SYNC_SYNCCONN_OFFSET;
+
+	} else if ( dn_match( &rdn, &current_bv ) ) {
+		Connection	*c;
+		ber_socket_t	connindex;
+
+		for ( n = 0, c = connection_first( &connindex );
+				c != NULL;
+				n++, c = connection_next( c, &connindex ) )
+		{
+			/* Ignore outbound connections */
+			if ( c->c_conn_state == SLAP_C_CLIENT )
+				n--;
+		}
+		connection_done( c );
+	}
+
+	if ( n != -1 ) {
+		Attribute	*a;
+		char		buf[LDAP_PVT_INTTYPE_CHARS(long)];
+		ber_len_t	len;
+
+		a = attr_find( e->e_attrs, mi->mi_ad_monitorCounter );
+		if ( a == NULL ) {
+			return( -1 );
+		}
+
+		snprintf( buf, sizeof( buf ), "%ld", n );
+		len = strlen( buf );
+		if ( len > a->a_vals[ 0 ].bv_len ) {
+			a->a_vals[ 0 ].bv_val = ber_memrealloc( a->a_vals[ 0 ].bv_val, len + 1 );
+		}
+		a->a_vals[ 0 ].bv_len = len;
+		AC_MEMCPY( a->a_vals[ 0 ].bv_val, buf, len + 1 );
+
+		/* FIXME: touch modifyTimestamp? */
+	}
+
+	return SLAP_CB_CONTINUE;
+}
+
+static int
+conn_create(
+	monitor_info_t		*mi,
+	Connection		*c,
+	Entry			**ep,
+	monitor_subsys_t	*ms )
+{
+	monitor_entry_t *mp;
+	struct tm	tm;
+	char		buf[ BACKMONITOR_BUFSIZE ];
+	char		buf2[ LDAP_LUTIL_GENTIME_BUFSIZE ];
+	char		buf3[ LDAP_LUTIL_GENTIME_BUFSIZE ];
+
+	struct berval bv, ctmbv, mtmbv;
+	struct berval bv_unknown= BER_BVC("unknown");
+
+	Entry		*e;
+
+	assert( c != NULL );
+	assert( ep != NULL );
+
+	ldap_pvt_gmtime( &c->c_starttime, &tm );
+
+	ctmbv.bv_len = lutil_gentime( buf2, sizeof( buf2 ), &tm );
+	ctmbv.bv_val = buf2;
+
+	ldap_pvt_gmtime( &c->c_activitytime, &tm );
+	mtmbv.bv_len = lutil_gentime( buf3, sizeof( buf3 ), &tm );
+	mtmbv.bv_val = buf3;
+
+	bv.bv_len = snprintf( buf, sizeof( buf ),
+		"cn=Connection %ld", c->c_connid );
+	bv.bv_val = buf;
+	e = monitor_entry_stub( &ms->mss_dn, &ms->mss_ndn, &bv, 
+		mi->mi_oc_monitorConnection, &ctmbv, &mtmbv );
+
+	if ( e == NULL) {
+		Debug( LDAP_DEBUG_ANY,
+			"monitor_subsys_conn_create: "
+			"unable to create entry "
+			"\"cn=Connection %ld,%s\"\n",
+			c->c_connid, 
+			ms->mss_dn.bv_val );
+		return( -1 );
+	}
+
+#ifdef MONITOR_LEGACY_CONN
+	/* NOTE: this will disappear, as the exploded data
+	 * has been moved to dedicated attributes */
+	bv.bv_len = snprintf( buf, sizeof( buf ),
+			"%ld "
+			": %ld "
+			": %ld/%ld/%ld/%ld "
+			": %ld/%ld/%ld "
+			": %s%s%s%s%s%s "
+			": %s "
+			": %s "
+			": %s "
+			": %s "
+			": %s "
+			": %s "
+			": %s",
+			c->c_connid,
+			(long) c->c_protocol,
+			c->c_n_ops_received, c->c_n_ops_executing,
+				c->c_n_ops_pending, c->c_n_ops_completed,
+			
+			/* add low-level counters here */
+			c->c_n_get, c->c_n_read, c->c_n_write,
+			
+			c->c_currentber ? "r" : "",
+			c->c_writewaiter ? "w" : "",
+			LDAP_STAILQ_EMPTY( &c->c_ops ) ? "" : "x",
+			LDAP_STAILQ_EMPTY( &c->c_pending_ops ) ? "" : "p",
+			connection_state2str( c->c_conn_state ),
+			c->c_sasl_bind_in_progress ? "S" : "",
+			
+			c->c_dn.bv_len ? c->c_dn.bv_val : SLAPD_ANONYMOUS,
+			
+			c->c_listener_url.bv_val,
+			BER_BVISNULL( &c->c_peer_domain )
+				? "" : c->c_peer_domain.bv_val,
+			BER_BVISNULL( &c->c_peer_name )
+				? "" : c->c_peer_name.bv_val,
+			c->c_sock_name.bv_val,
+			
+			buf2,
+			buf3 );
+	attr_merge_normalize_one( e, mi->mi_ad_monitoredInfo, &bv, NULL );
+#endif /* MONITOR_LEGACY_CONN */
+
+	bv.bv_len = snprintf( buf, sizeof( buf ), "%lu", c->c_connid );
+	attr_merge_one( e, mi->mi_ad_monitorConnectionNumber, &bv, NULL );
+
+	bv.bv_len = snprintf( buf, sizeof( buf ), "%ld", (long) c->c_protocol );
+	attr_merge_normalize_one( e, mi->mi_ad_monitorConnectionProtocol, &bv, NULL );
+
+	bv.bv_len = snprintf( buf, sizeof( buf ), "%ld", c->c_n_ops_received );
+	attr_merge_one( e, mi->mi_ad_monitorConnectionOpsReceived, &bv, NULL );
+
+	bv.bv_len = snprintf( buf, sizeof( buf ), "%ld", c->c_n_ops_executing );
+	attr_merge_one( e, mi->mi_ad_monitorConnectionOpsExecuting, &bv, NULL );
+
+	bv.bv_len = snprintf( buf, sizeof( buf ), "%ld", c->c_n_ops_pending );
+	attr_merge_one( e, mi->mi_ad_monitorConnectionOpsPending, &bv, NULL );
+
+	bv.bv_len = snprintf( buf, sizeof( buf ), "%ld", c->c_n_ops_completed );
+	attr_merge_one( e, mi->mi_ad_monitorConnectionOpsCompleted, &bv, NULL );
+
+	bv.bv_len = snprintf( buf, sizeof( buf ), "%ld", c->c_n_ops_async );
+	attr_merge_one( e, mi->mi_ad_monitorConnectionOpsAsync, &bv, NULL );
+
+	bv.bv_len = snprintf( buf, sizeof( buf ), "%ld", c->c_n_get );
+	attr_merge_one( e, mi->mi_ad_monitorConnectionGet, &bv, NULL );
+
+	bv.bv_len = snprintf( buf, sizeof( buf ), "%ld", c->c_n_read );
+	attr_merge_one( e, mi->mi_ad_monitorConnectionRead, &bv, NULL );
+
+	bv.bv_len = snprintf( buf, sizeof( buf ), "%ld", c->c_n_write );
+	attr_merge_one( e, mi->mi_ad_monitorConnectionWrite, &bv, NULL );
+
+	bv.bv_len = snprintf( buf, sizeof( buf ), "%s%s%s%s%s%s",
+			c->c_currentber ? "r" : "",
+			c->c_writewaiter ? "w" : "",
+			LDAP_STAILQ_EMPTY( &c->c_ops ) ? "" : "x",
+			LDAP_STAILQ_EMPTY( &c->c_pending_ops ) ? "" : "p",
+			connection_state2str( c->c_conn_state ),
+			c->c_sasl_bind_in_progress ? "S" : "" );
+	attr_merge_normalize_one( e, mi->mi_ad_monitorConnectionMask, &bv, NULL );
+
+	attr_merge_one( e, mi->mi_ad_monitorConnectionAuthzDN,
+		&c->c_dn, &c->c_ndn );
+
+	/* NOTE: client connections leave the c_peer_* fields NULL */
+	assert( !BER_BVISNULL( &c->c_listener_url ) );
+	attr_merge_normalize_one( e, mi->mi_ad_monitorConnectionListener,
+		&c->c_listener_url, NULL );
+
+	attr_merge_normalize_one( e, mi->mi_ad_monitorConnectionPeerDomain,
+		BER_BVISNULL( &c->c_peer_domain ) ? &bv_unknown : &c->c_peer_domain,
+		NULL );
+
+	attr_merge_normalize_one( e, mi->mi_ad_monitorConnectionPeerAddress,
+		BER_BVISNULL( &c->c_peer_name ) ? &bv_unknown : &c->c_peer_name,
+		NULL );
+
+	assert( !BER_BVISNULL( &c->c_sock_name ) );
+	attr_merge_normalize_one( e, mi->mi_ad_monitorConnectionLocalAddress,
+		&c->c_sock_name, NULL );
+
+	attr_merge_normalize_one( e, mi->mi_ad_monitorConnectionStartTime, &ctmbv, NULL );
+
+	attr_merge_normalize_one( e, mi->mi_ad_monitorConnectionActivityTime, &mtmbv, NULL );
+
+	mp = monitor_entrypriv_create();
+	if ( mp == NULL ) {
+		return LDAP_OTHER;
+	}
+	e->e_private = ( void * )mp;
+	mp->mp_info = ms;
+	mp->mp_flags = MONITOR_F_SUB | MONITOR_F_VOLATILE;
+
+	*ep = e;
+
+	return SLAP_CB_CONTINUE;
+}
+
+static int 
+monitor_subsys_conn_create( 
+	Operation		*op,
+	SlapReply		*rs,
+	struct berval		*ndn,
+	Entry 			*e_parent,
+	Entry			**ep )
+{
+	monitor_info_t	*mi = ( monitor_info_t * )op->o_bd->be_private;
+
+	int			rc = SLAP_CB_CONTINUE;
+	monitor_subsys_t	*ms;
+
+	assert( mi != NULL );
+	assert( e_parent != NULL );
+	assert( ep != NULL );
+
+	ms = (( monitor_entry_t *)e_parent->e_private)->mp_info;
+
+	*ep = NULL;
+
+	if ( ndn == NULL ) {
+		Connection	*c;
+		ber_socket_t	connindex;
+		Entry		*e = NULL,
+				*e_tmp = NULL;
+
+		/* create all the children of e_parent */
+		for ( c = connection_first( &connindex );
+				c != NULL;
+				c = connection_next( c, &connindex ) )
+		{
+			monitor_entry_t 	*mp;
+
+			/* ignore outbound for now, nothing to show */
+			if ( c->c_conn_state == SLAP_C_CLIENT )
+				continue;
+
+			if ( conn_create( mi, c, &e, ms ) != SLAP_CB_CONTINUE
+					|| e == NULL )
+			{
+				for ( ; e_tmp != NULL; ) {
+					mp = ( monitor_entry_t * )e_tmp->e_private;
+					e = mp->mp_next;
+
+					ch_free( mp );
+					e_tmp->e_private = NULL;
+					entry_free( e_tmp );
+
+					e_tmp = e;
+				}
+				rc = rs->sr_err = LDAP_OTHER;
+				break;
+			}
+			mp = ( monitor_entry_t * )e->e_private;
+			mp->mp_next = e_tmp;
+			e_tmp = e;
+		}
+		connection_done( c );
+		*ep = e;
+
+	} else {
+		Connection		*c;
+		ber_socket_t		connindex;
+		unsigned long 		connid;
+		char			*next = NULL;
+		static struct berval	nconn_bv = BER_BVC( "cn=connection " );
+
+		rc = LDAP_NO_SUCH_OBJECT;
+	       
+		/* create exactly the required entry;
+		 * the normalized DN must start with "cn=connection ",
+		 * followed by the connection id, followed by
+		 * the RDN separator "," */
+		if ( ndn->bv_len <= nconn_bv.bv_len
+				|| strncmp( ndn->bv_val, nconn_bv.bv_val, nconn_bv.bv_len ) != 0 )
+		{
+			return -1;
+		}
+		
+		connid = strtol( &ndn->bv_val[ nconn_bv.bv_len ], &next, 10 );
+		if ( next[ 0 ] != ',' ) {
+			return ( rs->sr_err = LDAP_OTHER );
+		}
+
+		for ( c = connection_first( &connindex );
+				c != NULL;
+				c = connection_next( c, &connindex ) )
+		{
+			if ( c->c_connid == connid ) {
+				rc = conn_create( mi, c, ep, ms );
+				if ( rc != SLAP_CB_CONTINUE ) {
+					rs->sr_err = rc;
+
+				} else if ( *ep == NULL ) {
+					rc = rs->sr_err = LDAP_OTHER;
+				}
+
+				break;
+			}
+		}
+		
+		connection_done( c );
+	}
+
+	return rc;
+}
+
diff --git a/servers/slapd/back-monitor/database.c b/servers/slapd/back-monitor/database.c
new file mode 100644
index 0000000..dc1100d
--- /dev/null
+++ b/servers/slapd/back-monitor/database.c
@@ -0,0 +1,1000 @@
+/* database.c - deals with database subsystem */
+/* $OpenLDAP$ */
+/* This work is part of OpenLDAP Software <http://www.openldap.org/>.
+ *
+ * Copyright 2001-2022 The OpenLDAP Foundation.
+ * Portions Copyright 2001-2003 Pierangelo Masarati.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted only as authorized by the OpenLDAP
+ * Public License.
+ *
+ * A copy of this license is available in file LICENSE in the
+ * top-level directory of the distribution or, alternatively, at
+ * <http://www.OpenLDAP.org/license.html>.
+ */
+/* ACKNOWLEDGEMENTS:
+ * This work was initially developed by Pierangelo Masarati for inclusion
+ * in OpenLDAP Software.
+ */
+
+#include "portable.h"
+
+#include <stdio.h>
+#include <ac/string.h>
+#include <ac/unistd.h>
+
+#include "slap.h"
+#include "back-monitor.h"
+
+#if defined(LDAP_SLAPI)
+#include "slapi.h"
+static int monitor_back_add_plugin( monitor_info_t *mi, Backend *be, Entry *e );
+#endif /* defined(LDAP_SLAPI) */
+
+static int
+monitor_subsys_database_modify(
+	Operation	*op,
+	SlapReply	*rs,
+	Entry		*e );
+
+static struct restricted_ops_t {
+	struct berval	op;
+	unsigned int	tag;
+} restricted_ops[] = {
+	{ BER_BVC( "add" ),			SLAP_RESTRICT_OP_ADD },
+	{ BER_BVC( "bind" ),			SLAP_RESTRICT_OP_BIND },
+	{ BER_BVC( "compare" ),			SLAP_RESTRICT_OP_COMPARE },
+	{ BER_BVC( "delete" ),			SLAP_RESTRICT_OP_DELETE },
+	{ BER_BVC( "extended" ),		SLAP_RESTRICT_OP_EXTENDED },
+	{ BER_BVC( "modify" ),			SLAP_RESTRICT_OP_MODIFY },
+	{ BER_BVC( "rename" ),			SLAP_RESTRICT_OP_RENAME },
+	{ BER_BVC( "search" ),			SLAP_RESTRICT_OP_SEARCH },
+	{ BER_BVNULL,				0 }
+}, restricted_exops[] = {
+	{ BER_BVC( LDAP_EXOP_START_TLS ),	SLAP_RESTRICT_EXOP_START_TLS },
+	{ BER_BVC( LDAP_EXOP_MODIFY_PASSWD ),	SLAP_RESTRICT_EXOP_MODIFY_PASSWD },
+	{ BER_BVC( LDAP_EXOP_WHO_AM_I ),	SLAP_RESTRICT_EXOP_WHOAMI },
+	{ BER_BVC( LDAP_EXOP_CANCEL ),	SLAP_RESTRICT_EXOP_CANCEL },
+	{ BER_BVNULL,				0 }
+};
+
+static int
+init_readOnly( monitor_info_t *mi, Entry *e, slap_mask_t restrictops )
+{
+	struct berval	*tf = ( ( restrictops & SLAP_RESTRICT_OP_MASK ) == SLAP_RESTRICT_OP_WRITES ) ?
+		(struct berval *)&slap_true_bv : (struct berval *)&slap_false_bv;
+
+	return attr_merge_one( e, mi->mi_ad_readOnly, tf, NULL );
+}
+
+static int
+init_restrictedOperation( monitor_info_t *mi, Entry *e, slap_mask_t restrictops )
+{
+	int	i, rc;
+
+	for ( i = 0; restricted_ops[ i ].op.bv_val; i++ ) {
+		if ( restrictops & restricted_ops[ i ].tag ) {
+			rc = attr_merge_one( e, mi->mi_ad_restrictedOperation,
+					&restricted_ops[ i ].op,
+					&restricted_ops[ i ].op );
+			if ( rc ) {
+				return rc;
+			}
+		}
+	}
+
+	for ( i = 0; restricted_exops[ i ].op.bv_val; i++ ) {
+		if ( restrictops & restricted_exops[ i ].tag ) {
+			rc = attr_merge_one( e, mi->mi_ad_restrictedOperation,
+					&restricted_exops[ i ].op,
+					&restricted_exops[ i ].op );
+			if ( rc ) {
+				return rc;
+			}
+		}
+	}
+
+	return LDAP_SUCCESS;
+}
+
+static int
+monitor_subsys_overlay_init_one(
+	monitor_info_t		*mi,
+	BackendDB		*be,
+	monitor_subsys_t	*ms,
+	monitor_subsys_t	*ms_overlay,
+	slap_overinst		*on,
+	Entry			*e_database,
+	Entry			**ep_overlay )
+{
+	char			buf[ BACKMONITOR_BUFSIZE ];
+	int			j, o;
+	Entry			*e_overlay;
+	slap_overinst		*on2;
+	slap_overinfo		*oi = NULL;
+	BackendInfo		*bi;
+	monitor_entry_t		*mp_overlay;
+	struct berval		bv;
+
+	assert( overlay_is_over( be ) );
+
+	oi = (slap_overinfo *)be->bd_info->bi_private;
+	bi = oi->oi_orig;
+
+	/* find the overlay number, o */
+	for ( o = 0, on2 = oi->oi_list; on2 && on2 != on; on2 = on2->on_next, o++ )
+		;
+
+	if ( on2 == NULL ) {
+		return -1;
+	}
+
+	/* find the overlay type number, j */
+	for ( on2 = overlay_next( NULL ), j = 0; on2; on2 = overlay_next( on2 ), j++ ) {
+		if ( on2->on_bi.bi_type == on->on_bi.bi_type ) {
+			break;
+		}
+	}
+	assert( on2 != NULL );
+
+	bv.bv_len = snprintf( buf, sizeof( buf ), "cn=Overlay %d", o );
+	bv.bv_val = buf;
+
+	e_overlay = monitor_entry_stub( &e_database->e_name, &e_database->e_nname, &bv,
+		mi->mi_oc_monitoredObject, NULL, NULL );
+
+	if ( e_overlay == NULL ) {
+		Debug( LDAP_DEBUG_ANY,
+			"monitor_subsys_overlay_init_one: "
+			"unable to create entry "
+			"\"cn=Overlay %d,%s\"\n",
+			o, e_database->e_name.bv_val );
+		return( -1 );
+	}
+	ber_str2bv( on->on_bi.bi_type, 0, 0, &bv );
+	attr_merge_normalize_one( e_overlay, mi->mi_ad_monitoredInfo, &bv, NULL );
+
+	bv.bv_len = snprintf( buf, sizeof( buf ), "cn=Overlay %d,%s",
+		j, ms_overlay->mss_dn.bv_val );
+	bv.bv_val = buf;
+	attr_merge_normalize_one( e_overlay, slap_schema.si_ad_seeAlso,
+		&bv, NULL );
+
+	if ( SLAP_MONITOR( be ) ) {
+		attr_merge( e_overlay, slap_schema.si_ad_monitorContext,
+				be->be_suffix, be->be_nsuffix );
+
+	} else {
+		attr_merge( e_overlay, slap_schema.si_ad_namingContexts,
+				be->be_suffix, be->be_nsuffix );
+	}
+
+	mp_overlay = monitor_entrypriv_create();
+	if ( mp_overlay == NULL ) {
+		return -1;
+	}
+	e_overlay->e_private = ( void * )mp_overlay;
+	mp_overlay->mp_info = ms;
+	mp_overlay->mp_flags = ms->mss_flags | MONITOR_F_SUB;
+	
+	if ( monitor_cache_add( mi, e_overlay, e_database ) ) {
+		Debug( LDAP_DEBUG_ANY,
+			"monitor_subsys_overlay_init_one: "
+			"unable to add entry "
+			"\"cn=Overlay %d,%s\"\n",
+			o, e_database->e_name.bv_val );
+		return -1;
+	}
+
+	*ep_overlay = e_overlay;
+	return 0;
+}
+
+static int
+monitor_subsys_database_init_one(
+	monitor_info_t		*mi,
+	BackendDB		*be,
+	monitor_subsys_t	*ms,
+	monitor_subsys_t	*ms_backend,
+	monitor_subsys_t	*ms_overlay,
+	struct berval		*rdn,
+	Entry			*e_database,
+	struct slap_overinst	*overlay,
+	Entry			**ep )
+{
+	char			buf[ BACKMONITOR_BUFSIZE ];
+	int			j;
+	slap_overinfo		*oi = NULL;
+	BackendInfo		*bi, *bi2;
+	Entry			*e;
+	monitor_entry_t		*mp;
+	char			*rdnval = strchr( rdn->bv_val, '=' ) + 1;
+	struct berval		bv;
+
+	bi = be->bd_info;
+
+	if ( be->be_suffix == NULL ) {
+		Debug( LDAP_DEBUG_ANY,
+			"monitor_subsys_database_init_one: "
+			"missing suffix for %s\n",
+			rdnval );
+		return( -1 );
+	}
+
+	if ( overlay_is_over( be ) ) {
+		oi = (slap_overinfo *)be->bd_info->bi_private;
+		bi = oi->oi_orig;
+	}
+
+	e = monitor_entry_stub( &ms->mss_dn, &ms->mss_ndn, rdn,
+		mi->mi_oc_monitoredObject, NULL, NULL );
+
+	if ( e == NULL ) {
+		Debug( LDAP_DEBUG_ANY,
+			"monitor_subsys_database_init_one: "
+			"unable to create entry \"%s,%s\"\n",
+			rdn->bv_val, ms->mss_dn.bv_val );
+		return( -1 );
+	}
+
+	ber_str2bv( bi->bi_type, 0, 0, &bv );
+	attr_merge_normalize_one( e, mi->mi_ad_monitoredInfo, &bv, NULL );
+	attr_merge_one( e, mi->mi_ad_monitorIsShadow,
+		SLAP_SHADOW( be ) ? (struct berval *)&slap_true_bv :
+			(struct berval *)&slap_false_bv, NULL );
+
+	if ( SLAP_MONITOR( be ) ) {
+		attr_merge( e, slap_schema.si_ad_monitorContext,
+				be->be_suffix, be->be_nsuffix );
+		attr_merge( e_database, slap_schema.si_ad_monitorContext,
+				be->be_suffix, be->be_nsuffix );
+
+	} else {
+		attr_merge( e, slap_schema.si_ad_namingContexts,
+			be->be_suffix, be->be_nsuffix );
+		attr_merge( e_database, slap_schema.si_ad_namingContexts,
+			be->be_suffix, be->be_nsuffix );
+
+		if ( SLAP_GLUE_SUBORDINATE( be ) ) {
+			BackendDB *sup_be = select_backend( &be->be_nsuffix[ 0 ], 1 );
+			if ( sup_be == NULL ) {
+				Debug( LDAP_DEBUG_ANY,
+					"monitor_subsys_database_init: "
+					"unable to get superior for %s\n",
+					be->be_suffix[ 0 ].bv_val );
+
+			} else {
+				attr_merge( e, mi->mi_ad_monitorSuperiorDN,
+					sup_be->be_suffix, sup_be->be_nsuffix );
+			}
+		}
+	}
+
+	(void)init_readOnly( mi, e, be->be_restrictops );
+	(void)init_restrictedOperation( mi, e, be->be_restrictops );
+
+	if ( SLAP_SHADOW( be ) && be->be_update_refs ) {
+		attr_merge_normalize( e, mi->mi_ad_monitorUpdateRef,
+				be->be_update_refs, NULL );
+	}
+
+	if ( oi != NULL ) {
+		slap_overinst	*on = oi->oi_list,
+				*on1 = on;
+
+		for ( ; on; on = on->on_next ) {
+			slap_overinst		*on2;
+
+			for ( on2 = on1; on2 != on; on2 = on2->on_next ) {
+				if ( on2->on_bi.bi_type == on->on_bi.bi_type ) {
+					break;
+				}
+			}
+
+			if ( on2 != on ) {
+				break;
+			}
+			
+			ber_str2bv( on->on_bi.bi_type, 0, 0, &bv );
+			attr_merge_normalize_one( e, mi->mi_ad_monitorOverlay,
+					&bv, NULL );
+
+			/* find the overlay number, j */
+			for ( on2 = overlay_next( NULL ), j = 0; on2; on2 = overlay_next( on2 ), j++ ) {
+				if ( on2->on_bi.bi_type == on->on_bi.bi_type ) {
+					break;
+				}
+			}
+			assert( on2 != NULL );
+
+			snprintf( buf, sizeof( buf ), 
+				"cn=Overlay %d,%s", 
+				j, ms_overlay->mss_dn.bv_val );
+			ber_str2bv( buf, 0, 0, &bv );
+			attr_merge_normalize_one( e,
+					slap_schema.si_ad_seeAlso,
+					&bv, NULL );
+		}
+	}
+
+	j = -1;
+	LDAP_STAILQ_FOREACH( bi2, &backendInfo, bi_next ) {
+		j++;
+		if ( bi2->bi_type == bi->bi_type ) {
+			snprintf( buf, sizeof( buf ), 
+				"cn=Backend %d,%s", 
+				j, ms_backend->mss_dn.bv_val );
+			bv.bv_val = buf;
+			bv.bv_len = strlen( buf );
+			attr_merge_normalize_one( e,
+					slap_schema.si_ad_seeAlso,
+					&bv, NULL );
+			break;
+		}
+	}
+	/* we must find it! */
+	assert( j >= 0 );
+
+	mp = monitor_entrypriv_create();
+	if ( mp == NULL ) {
+		return -1;
+	}
+	e->e_private = ( void * )mp;
+	mp->mp_info = ms;
+	mp->mp_flags = ms->mss_flags
+		| MONITOR_F_SUB;
+	mp->mp_private = be;
+
+	if ( monitor_cache_add( mi, e, e_database ) ) {
+		Debug( LDAP_DEBUG_ANY,
+			"monitor_subsys_database_init_one: "
+			"unable to add entry \"%s,%s\"\n",
+			rdn->bv_val, ms->mss_dn.bv_val );
+		return( -1 );
+	}
+
+#if defined(LDAP_SLAPI)
+	monitor_back_add_plugin( mi, be, e );
+#endif /* defined(LDAP_SLAPI) */
+
+	if ( oi != NULL ) {
+		Entry		*e_overlay;
+		slap_overinst	*on = oi->oi_list;
+
+		for ( ; on; on = on->on_next ) {
+			monitor_subsys_overlay_init_one( mi, be,
+				ms, ms_overlay, on, e, &e_overlay );
+			if ( overlay == on ) {
+				*ep = e_overlay;
+			}
+		}
+	}
+	if ( overlay == NULL ) {
+		*ep = e;
+	}
+
+	return 0;
+}
+
+static int
+monitor_back_register_database_and_overlay(
+	BackendDB		*be,
+	struct slap_overinst	*on,
+	struct berval		*ndn_out )
+{
+	monitor_info_t		*mi;
+	Entry			*e_database, *e = NULL;
+	int			i, rc;
+	monitor_entry_t		*mp;
+	monitor_subsys_t	*ms_backend,
+				*ms_database,
+				*ms_overlay;
+	struct berval		bv;
+	char			buf[ BACKMONITOR_BUFSIZE ];
+
+	assert( be_monitor != NULL );
+
+	if ( !monitor_subsys_is_opened() ) {
+		if ( on ) {
+			return monitor_back_register_overlay_limbo( be, on, ndn_out );
+
+		} else {
+			return monitor_back_register_database_limbo( be, ndn_out );
+		}
+	}
+
+	mi = ( monitor_info_t * )be_monitor->be_private;
+
+	ms_backend = monitor_back_get_subsys( SLAPD_MONITOR_BACKEND_NAME );
+	if ( ms_backend == NULL ) {
+		Debug( LDAP_DEBUG_ANY,
+			"monitor_back_register_database: "
+			"unable to get "
+			"\"" SLAPD_MONITOR_BACKEND_NAME "\" "
+			"subsystem\n" );
+		return -1;
+	}
+
+	ms_database = monitor_back_get_subsys( SLAPD_MONITOR_DATABASE_NAME );
+	if ( ms_database == NULL ) {
+		Debug( LDAP_DEBUG_ANY,
+			"monitor_back_register_database: "
+			"unable to get "
+			"\"" SLAPD_MONITOR_DATABASE_NAME "\" "
+			"subsystem\n" );
+		return -1;
+	}
+
+	ms_overlay = monitor_back_get_subsys( SLAPD_MONITOR_OVERLAY_NAME );
+	if ( ms_overlay == NULL ) {
+		Debug( LDAP_DEBUG_ANY,
+			"monitor_back_register_database: "
+			"unable to get "
+			"\"" SLAPD_MONITOR_OVERLAY_NAME "\" "
+			"subsystem\n" );
+		return -1;
+	}
+
+	if ( monitor_cache_get( mi, &ms_database->mss_ndn, &e_database ) ) {
+		Debug( LDAP_DEBUG_ANY,
+			"monitor_subsys_database_init: "
+			"unable to get entry \"%s\"\n",
+			ms_database->mss_ndn.bv_val );
+		return( -1 );
+	}
+
+	/* FIXME: It's only safe since we're paused */
+	mp = ( monitor_entry_t * )e_database->e_private;
+	for ( i = -1, e = mp->mp_children; e; i++ ) {
+		mp = ( monitor_entry_t * )e->e_private;
+
+		assert( mp != NULL );
+		if ( mp->mp_private == be->bd_self ) {
+			rc = 0;
+			goto done;
+		}
+		e = mp->mp_next;
+	}
+
+	bv.bv_val = buf;
+	bv.bv_len = snprintf( buf, sizeof( buf ), "cn=Database %d", i );
+	if ( bv.bv_len >= sizeof( buf ) ) {
+		rc = -1;
+		goto done;
+	}
+	
+	rc = monitor_subsys_database_init_one( mi, be,
+		ms_database, ms_backend, ms_overlay, &bv, e_database, on, &e );
+	if ( rc != 0 ) {
+		goto done;
+	}
+
+done:;
+	monitor_cache_release( mi, e_database );
+	if ( rc == 0 && ndn_out && e ) {
+		*ndn_out = e->e_nname;
+	}
+
+	return rc;
+}
+
+int
+monitor_back_register_database(
+	BackendDB		*be,
+	struct berval		*ndn_out )
+{
+	return monitor_back_register_database_and_overlay( be, NULL, ndn_out );
+}
+
+int
+monitor_back_register_overlay(
+	BackendDB		*be,
+	struct slap_overinst	*on,
+	struct berval		*ndn_out )
+{
+	return monitor_back_register_database_and_overlay( be, on, ndn_out );
+}
+
+int
+monitor_subsys_database_init(
+	BackendDB		*be,
+	monitor_subsys_t	*ms )
+{
+	monitor_info_t		*mi;
+	Entry			*e_database, *e;
+	int			i, rc;
+	monitor_subsys_t	*ms_backend,
+				*ms_overlay;
+	struct berval		bv;
+
+	assert( be != NULL );
+
+	ms->mss_modify = monitor_subsys_database_modify;
+
+	mi = ( monitor_info_t * )be->be_private;
+
+	ms_backend = monitor_back_get_subsys( SLAPD_MONITOR_BACKEND_NAME );
+	if ( ms_backend == NULL ) {
+		Debug( LDAP_DEBUG_ANY,
+			"monitor_subsys_database_init: "
+			"unable to get "
+			"\"" SLAPD_MONITOR_BACKEND_NAME "\" "
+			"subsystem\n" );
+		return -1;
+	}
+
+	ms_overlay = monitor_back_get_subsys( SLAPD_MONITOR_OVERLAY_NAME );
+	if ( ms_overlay == NULL ) {
+		Debug( LDAP_DEBUG_ANY,
+			"monitor_subsys_database_init: "
+			"unable to get "
+			"\"" SLAPD_MONITOR_OVERLAY_NAME "\" "
+			"subsystem\n" );
+		return -1;
+	}
+
+	if ( monitor_cache_get( mi, &ms->mss_ndn, &e_database ) ) {
+		Debug( LDAP_DEBUG_ANY,
+			"monitor_subsys_database_init: "
+			"unable to get entry \"%s\"\n",
+			ms->mss_ndn.bv_val );
+		return( -1 );
+	}
+
+	(void)init_readOnly( mi, e_database, frontendDB->be_restrictops );
+	(void)init_restrictedOperation( mi, e_database, frontendDB->be_restrictops );
+
+	BER_BVSTR( &bv, "cn=Frontend" );
+	rc = monitor_subsys_database_init_one( mi, frontendDB,
+		ms, ms_backend, ms_overlay, &bv, e_database, NULL, &e );
+	if ( rc != 0 ) {
+		return rc;
+	}
+
+	i = -1;
+	LDAP_STAILQ_FOREACH( be, &backendDB, be_next ) {
+		char		buf[ BACKMONITOR_BUFSIZE ];
+
+		bv.bv_val = buf;
+		bv.bv_len = snprintf( buf, sizeof( buf ), "cn=Database %d", ++i );
+		if ( bv.bv_len >= sizeof( buf ) ) {
+			return -1;
+		}
+		
+		rc = monitor_subsys_database_init_one( mi, be,
+			ms, ms_backend, ms_overlay, &bv, e_database, NULL, &e );
+		if ( rc != 0 ) {
+			return rc;
+		}
+	}
+	
+	monitor_cache_release( mi, e_database );
+
+	return( 0 );
+}
+
+/*
+ * v: array of values
+ * cur: must not contain the tags corresponding to the values in v
+ * delta: will contain the tags corresponding to the values in v
+ */
+static int
+value_mask( BerVarray v, slap_mask_t cur, slap_mask_t *delta )
+{
+	for ( ; !BER_BVISNULL( v ); v++ ) {
+		struct restricted_ops_t		*rops;
+		int				i;
+
+		if ( OID_LEADCHAR( v->bv_val[ 0 ] ) ) {
+			rops = restricted_exops;
+
+		} else {
+			rops = restricted_ops;
+		}
+
+		for ( i = 0; !BER_BVISNULL( &rops[ i ].op ); i++ ) {
+			if ( ber_bvstrcasecmp( v, &rops[ i ].op ) != 0 ) {
+				continue;
+			}
+
+			if ( rops[ i ].tag & *delta ) {
+				return LDAP_OTHER;
+			}
+
+			if ( rops[ i ].tag & cur ) {
+				return LDAP_OTHER;
+			}
+
+			cur |= rops[ i ].tag;
+			*delta |= rops[ i ].tag;
+
+			break;
+		}
+
+		if ( BER_BVISNULL( &rops[ i ].op ) ) {
+			return LDAP_INVALID_SYNTAX;
+		}
+	}
+
+	return LDAP_SUCCESS;
+}
+
+static int
+monitor_subsys_database_modify(
+	Operation	*op,
+	SlapReply	*rs,
+	Entry		*e )
+{
+	monitor_info_t	*mi = (monitor_info_t *)op->o_bd->be_private;
+	int		rc = LDAP_OTHER;
+	Attribute	*save_attrs, *a;
+	Modifications	*ml;
+	Backend		*be;
+	int		ro_gotval = 1, i, n;
+	slap_mask_t	rp_add = 0, rp_delete = 0, rp_cur;
+	struct berval	*tf;
+	
+	i = sscanf( e->e_nname.bv_val, "cn=database %d,", &n );
+	if ( i != 1 ) {
+		return SLAP_CB_CONTINUE;
+	}
+
+	if ( n < 0 || n >= nBackendDB ) {
+		rs->sr_text = "invalid database index";
+		return ( rs->sr_err = LDAP_NO_SUCH_OBJECT );
+	}
+
+	LDAP_STAILQ_FOREACH( be, &backendDB, be_next ) {
+		if ( n == 0 ) {
+			break;
+		}
+		n--;
+	}
+	/* do not allow some changes on back-monitor (needs work)... */
+	if ( SLAP_MONITOR( be ) ) {
+		rs->sr_text = "no modifications allowed to monitor database entry";
+		return ( rs->sr_err = LDAP_UNWILLING_TO_PERFORM );
+	}
+		
+	rp_cur = be->be_restrictops;
+
+	save_attrs = e->e_attrs;
+	e->e_attrs = attrs_dup( e->e_attrs );
+
+	for ( ml = op->orm_modlist; ml; ml = ml->sml_next ) {
+		Modification *mod = &ml->sml_mod;
+
+		if ( mod->sm_desc == mi->mi_ad_readOnly ) {
+			int	val = -1;
+
+			if ( mod->sm_values ) {
+				if ( !BER_BVISNULL( &mod->sm_values[ 1 ] ) ) {
+					rs->sr_text = "attempting to modify multiple values of single-valued attribute";
+					rc = rs->sr_err = LDAP_CONSTRAINT_VIOLATION;
+					goto done;
+				}
+
+				if ( bvmatch( &slap_true_bv, mod->sm_values )) {
+					val = 1;
+
+				} else if ( bvmatch( &slap_false_bv, mod->sm_values )) {
+					val = 0;
+
+				} else {
+					assert( 0 );
+					rc = rs->sr_err = LDAP_INVALID_SYNTAX;
+					goto done;
+				}
+			}
+
+			switch ( mod->sm_op ) {
+			case LDAP_MOD_DELETE:
+				if ( ro_gotval < 1 ) {
+					rc = rs->sr_err = LDAP_CONSTRAINT_VIOLATION;
+					goto done;
+				}
+				ro_gotval--;
+
+				if ( val == 0 && ( rp_cur & SLAP_RESTRICT_OP_WRITES ) == SLAP_RESTRICT_OP_WRITES ) {
+					rc = rs->sr_err = LDAP_NO_SUCH_ATTRIBUTE;
+					goto done;
+				}
+				
+				if ( val == 1 && ( rp_cur & SLAP_RESTRICT_OP_WRITES ) != SLAP_RESTRICT_OP_WRITES ) {
+					rc = rs->sr_err = LDAP_NO_SUCH_ATTRIBUTE;
+					goto done;
+				}
+				
+				break;
+
+			case LDAP_MOD_REPLACE:
+				ro_gotval = 0;
+				/* fall thru */
+
+			case LDAP_MOD_ADD:
+				if ( ro_gotval > 0 ) {
+					rc = rs->sr_err = LDAP_CONSTRAINT_VIOLATION;
+					goto done;
+				}
+				ro_gotval++;
+
+				if ( val == 1 ) {
+					rp_add |= (~rp_cur) & SLAP_RESTRICT_OP_WRITES;
+					rp_cur |= SLAP_RESTRICT_OP_WRITES;
+					rp_delete &= ~SLAP_RESTRICT_OP_WRITES;
+					
+				} else if ( val == 0 ) {
+					rp_delete |= rp_cur & SLAP_RESTRICT_OP_WRITES;
+					rp_cur &= ~SLAP_RESTRICT_OP_WRITES;
+					rp_add &= ~SLAP_RESTRICT_OP_WRITES;
+				}
+				break;
+
+			default:
+				rc = rs->sr_err = LDAP_OTHER;
+				goto done;
+			}
+
+		} else if ( mod->sm_desc == mi->mi_ad_restrictedOperation ) {
+			slap_mask_t	mask = 0;
+
+			switch ( mod->sm_op ) {
+			case LDAP_MOD_DELETE:
+				if ( mod->sm_values == NULL ) {
+					rp_delete = rp_cur;
+					rp_cur = 0;
+					rp_add = 0;
+					break;
+				}
+				rc = value_mask( mod->sm_values, ~rp_cur, &mask );
+				if ( rc == LDAP_SUCCESS ) {
+					rp_delete |= mask;
+					rp_add &= ~mask;
+					rp_cur &= ~mask;
+
+				} else if ( rc == LDAP_OTHER ) {
+					rc = LDAP_NO_SUCH_ATTRIBUTE;
+				}
+				break;
+
+			case LDAP_MOD_REPLACE:
+				rp_delete = rp_cur;
+				rp_cur = 0;
+				rp_add = 0;
+				/* fall thru */
+
+			case LDAP_MOD_ADD:
+				rc = value_mask( mod->sm_values, rp_cur, &mask );
+				if ( rc == LDAP_SUCCESS ) {
+					rp_add |= mask;
+					rp_cur |= mask;
+					rp_delete &= ~mask;
+
+				} else if ( rc == LDAP_OTHER ) {
+					rc = rs->sr_err = LDAP_TYPE_OR_VALUE_EXISTS;
+				}
+				break;
+
+			default:
+				rc = rs->sr_err = LDAP_OTHER;
+				break;
+			}
+
+			if ( rc != LDAP_SUCCESS ) {
+				goto done;
+			}
+
+		} else if ( is_at_operational( mod->sm_desc->ad_type )) {
+		/* accept all operational attributes */
+			attr_delete( &e->e_attrs, mod->sm_desc );
+			rc = attr_merge( e, mod->sm_desc, mod->sm_values,
+				mod->sm_nvalues );
+			if ( rc ) {
+				rc = rs->sr_err = LDAP_OTHER;
+				break;
+			}
+
+		} else {
+			rc = rs->sr_err = LDAP_UNWILLING_TO_PERFORM;
+			break;
+		}
+	}
+
+	/* sanity checks: */
+	if ( ro_gotval < 1 ) {
+		rc = rs->sr_err = LDAP_CONSTRAINT_VIOLATION;
+		goto done;
+	}
+
+	if ( ( rp_cur & SLAP_RESTRICT_OP_EXTENDED ) && ( rp_cur & SLAP_RESTRICT_EXOP_MASK ) ) {
+		rc = rs->sr_err = LDAP_CONSTRAINT_VIOLATION;
+		goto done;
+	}
+
+	if ( rp_delete & rp_add ) {
+		rc = rs->sr_err = LDAP_OTHER;
+		goto done;
+	}
+
+	/* check current value of readOnly */
+	if ( ( rp_cur & SLAP_RESTRICT_OP_WRITES ) == SLAP_RESTRICT_OP_WRITES ) {
+		tf = (struct berval *)&slap_true_bv;
+
+	} else {
+		tf = (struct berval *)&slap_false_bv;
+	}
+
+	a = attr_find( e->e_attrs, mi->mi_ad_readOnly );
+	if ( a == NULL ) {
+		rc = LDAP_OTHER;
+		goto done;
+	}
+
+	if ( !bvmatch( &a->a_vals[ 0 ], tf ) ) {
+		attr_delete( &e->e_attrs, mi->mi_ad_readOnly );
+		rc = attr_merge_one( e, mi->mi_ad_readOnly, tf, tf );
+	}
+
+	if ( rc == LDAP_SUCCESS ) {
+		if ( rp_delete ) {
+			if ( rp_delete == be->be_restrictops ) {
+				attr_delete( &e->e_attrs, mi->mi_ad_restrictedOperation );
+
+			} else {
+				a = attr_find( e->e_attrs, mi->mi_ad_restrictedOperation );
+				if ( a == NULL ) {
+					rc = rs->sr_err = LDAP_OTHER;
+					goto done;
+				}
+
+				for ( i = 0; !BER_BVISNULL( &restricted_ops[ i ].op ); i++ ) {
+					if ( rp_delete & restricted_ops[ i ].tag ) {
+						int	j;
+					
+						for ( j = 0; !BER_BVISNULL( &a->a_nvals[ j ] ); j++ ) {
+							int		k;
+
+							if ( !bvmatch( &a->a_nvals[ j ], &restricted_ops[ i ].op ) ) {
+								continue;
+							}
+
+							ch_free( a->a_vals[ j ].bv_val );
+							ch_free( a->a_nvals[ j ].bv_val );
+
+							for ( k = j + 1; !BER_BVISNULL( &a->a_nvals[ k ] ); k++ ) {
+								a->a_vals[ k - 1 ] = a->a_vals[ k ];
+								a->a_nvals[ k - 1 ] = a->a_nvals[ k ];
+							}
+	
+							BER_BVZERO( &a->a_vals[ k - 1 ] );
+							BER_BVZERO( &a->a_nvals[ k - 1 ] );
+							a->a_numvals--;
+						}
+					}
+				}
+				
+				for ( i = 0; !BER_BVISNULL( &restricted_exops[ i ].op ); i++ ) {
+					if ( rp_delete & restricted_exops[ i ].tag ) {
+						int	j;
+					
+						for ( j = 0; !BER_BVISNULL( &a->a_nvals[ j ] ); j++ ) {
+							int		k;
+
+							if ( !bvmatch( &a->a_nvals[ j ], &restricted_exops[ i ].op ) ) {
+								continue;
+							}
+
+							ch_free( a->a_vals[ j ].bv_val );
+							ch_free( a->a_nvals[ j ].bv_val );
+
+							for ( k = j + 1; !BER_BVISNULL( &a->a_nvals[ k ] ); k++ ) {
+								a->a_vals[ k - 1 ] = a->a_vals[ k ];
+								a->a_nvals[ k - 1 ] = a->a_nvals[ k ];
+							}
+	
+							BER_BVZERO( &a->a_vals[ k - 1 ] );
+							BER_BVZERO( &a->a_nvals[ k - 1 ] );
+							a->a_numvals--;
+						}
+					}
+				}
+
+				if ( a->a_vals == NULL ) {
+					assert( a->a_numvals == 0 );
+
+					attr_delete( &e->e_attrs, mi->mi_ad_restrictedOperation );
+				}
+			}
+		}
+
+		if ( rp_add ) {
+			for ( i = 0; !BER_BVISNULL( &restricted_ops[ i ].op ); i++ ) {
+				if ( rp_add & restricted_ops[ i ].tag ) {
+					attr_merge_one( e, mi->mi_ad_restrictedOperation,
+							&restricted_ops[ i ].op,
+							&restricted_ops[ i ].op );
+				}
+			}
+
+			for ( i = 0; !BER_BVISNULL( &restricted_exops[ i ].op ); i++ ) {
+				if ( rp_add & restricted_exops[ i ].tag ) {
+					attr_merge_one( e, mi->mi_ad_restrictedOperation,
+							&restricted_exops[ i ].op,
+							&restricted_exops[ i ].op );
+				}
+			}
+		}
+	}
+
+	be->be_restrictops = rp_cur;
+
+done:;
+	if ( rc == LDAP_SUCCESS ) {
+		attrs_free( save_attrs );
+		rc = SLAP_CB_CONTINUE;
+
+	} else {
+		Attribute *tmp = e->e_attrs;
+		e->e_attrs = save_attrs;
+		attrs_free( tmp );
+	}
+	return rc;
+}
+
+#if defined(LDAP_SLAPI)
+static int
+monitor_back_add_plugin( monitor_info_t *mi, Backend *be, Entry *e_database )
+{
+	Slapi_PBlock	*pCurrentPB; 
+	int		i, rc = LDAP_SUCCESS;
+
+	if ( slapi_int_pblock_get_first( be, &pCurrentPB ) != LDAP_SUCCESS ) {
+		/*
+		 * LDAP_OTHER is returned if no plugins are installed
+		 */
+		rc = LDAP_OTHER;
+		goto done;
+	}
+
+	i = 0;
+	do {
+		Slapi_PluginDesc	*srchdesc;
+		char			buf[ BACKMONITOR_BUFSIZE ];
+		struct berval		bv;
+
+		rc = slapi_pblock_get( pCurrentPB, SLAPI_PLUGIN_DESCRIPTION,
+				&srchdesc );
+		if ( rc != LDAP_SUCCESS ) {
+			goto done;
+		}
+		if ( srchdesc ) {
+			snprintf( buf, sizeof(buf),
+					"plugin %d name: %s; "
+					"vendor: %s; "
+					"version: %s; "
+					"description: %s", 
+					i,
+					srchdesc->spd_id,
+					srchdesc->spd_vendor,
+					srchdesc->spd_version,
+					srchdesc->spd_description );
+		} else {
+			snprintf( buf, sizeof(buf),
+					"plugin %d name: <no description available>", i );
+		}
+
+		ber_str2bv( buf, 0, 0, &bv );
+		attr_merge_normalize_one( e_database,
+				mi->mi_ad_monitoredInfo, &bv, NULL );
+
+		i++;
+
+	} while ( ( slapi_int_pblock_get_next( &pCurrentPB ) == LDAP_SUCCESS )
+			&& ( pCurrentPB != NULL ) );
+
+done:
+	return rc;
+}
+#endif /* defined(LDAP_SLAPI) */
diff --git a/servers/slapd/back-monitor/entry.c b/servers/slapd/back-monitor/entry.c
new file mode 100644
index 0000000..027dcc3
--- /dev/null
+++ b/servers/slapd/back-monitor/entry.c
@@ -0,0 +1,236 @@
+/* entry.c - monitor backend entry handling routines */
+/* $OpenLDAP$ */
+/* This work is part of OpenLDAP Software <http://www.openldap.org/>.
+ *
+ * Copyright 2001-2022 The OpenLDAP Foundation.
+ * Portions Copyright 2001-2003 Pierangelo Masarati.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted only as authorized by the OpenLDAP
+ * Public License.
+ *
+ * A copy of this license is available in file LICENSE in the
+ * top-level directory of the distribution or, alternatively, at
+ * <http://www.OpenLDAP.org/license.html>.
+ */
+/* ACKNOWLEDGEMENTS:
+ * This work was initially developed by Pierangelo Masarati for inclusion
+ * in OpenLDAP Software.
+ */
+
+#include "portable.h"
+
+#include <slap.h>
+#include "back-monitor.h"
+
+int
+monitor_entry_update(
+	Operation		*op,
+	SlapReply		*rs,
+	Entry 			*e
+)
+{
+	monitor_info_t	*mi = ( monitor_info_t * )op->o_bd->be_private;
+	monitor_entry_t *mp;
+
+	int		rc = SLAP_CB_CONTINUE;
+
+	assert( mi != NULL );
+	assert( e != NULL );
+	assert( e->e_private != NULL );
+
+	mp = ( monitor_entry_t * )e->e_private;
+
+	if ( mp->mp_cb ) {
+		struct monitor_callback_t	*mc;
+
+		for ( mc = mp->mp_cb; mc; mc = mc->mc_next ) {
+			if ( mc->mc_update ) {
+				rc = mc->mc_update( op, rs, e, mc->mc_private );
+				if ( rc != SLAP_CB_CONTINUE ) {
+					break;
+				}
+			}
+		}
+	}
+
+	if ( rc == SLAP_CB_CONTINUE && mp->mp_info && mp->mp_info->mss_update ) {
+		rc = mp->mp_info->mss_update( op, rs, e );
+	}
+
+	if ( rc == SLAP_CB_CONTINUE ) {
+		rc = LDAP_SUCCESS;
+	}
+
+	return rc;
+}
+
+int
+monitor_entry_create(
+	Operation		*op,
+	SlapReply		*rs,
+	struct berval		*ndn,
+	Entry			*e_parent,
+	Entry			**ep )
+{
+	monitor_info_t	*mi = ( monitor_info_t * )op->o_bd->be_private;
+	monitor_entry_t *mp;
+
+	int		rc = SLAP_CB_CONTINUE;
+
+	assert( mi != NULL );
+	assert( e_parent != NULL );
+	assert( e_parent->e_private != NULL );
+	assert( ep != NULL );
+
+	mp = ( monitor_entry_t * )e_parent->e_private;
+
+	if ( mp->mp_info && mp->mp_info->mss_create ) {
+		rc = mp->mp_info->mss_create( op, rs, ndn, e_parent, ep );
+	}
+
+	if ( rc == SLAP_CB_CONTINUE ) {
+		rc = LDAP_SUCCESS;
+	}
+	
+	return rc;
+}
+
+int
+monitor_entry_modify(
+	Operation		*op,
+	SlapReply		*rs,
+	Entry 			*e
+)
+{
+	monitor_info_t	*mi = ( monitor_info_t * )op->o_bd->be_private;
+	monitor_entry_t *mp;
+
+	int		rc = SLAP_CB_CONTINUE;
+
+	assert( mi != NULL );
+	assert( e != NULL );
+	assert( e->e_private != NULL );
+
+	mp = ( monitor_entry_t * )e->e_private;
+
+	if ( mp->mp_cb ) {
+		struct monitor_callback_t	*mc;
+
+		for ( mc = mp->mp_cb; mc; mc = mc->mc_next ) {
+			if ( mc->mc_modify ) {
+				rc = mc->mc_modify( op, rs, e, mc->mc_private );
+				if ( rc != SLAP_CB_CONTINUE ) {
+					break;
+				}
+			}
+		}
+	}
+
+	if ( rc == SLAP_CB_CONTINUE && mp->mp_info && mp->mp_info->mss_modify ) {
+		rc = mp->mp_info->mss_modify( op, rs, e );
+	}
+
+	if ( rc == SLAP_CB_CONTINUE ) {
+		rc = LDAP_SUCCESS;
+	}
+
+	return rc;
+}
+
+int
+monitor_entry_test_flags(
+	monitor_entry_t		*mp,
+	int			cond
+)
+{
+	assert( mp != NULL );
+
+	return( ( mp->mp_flags & cond ) || ( mp->mp_info->mss_flags & cond ) );
+}
+
+monitor_entry_t *
+monitor_back_entrypriv_create( void )
+{
+	monitor_entry_t	*mp;
+
+	mp = ( monitor_entry_t * )ch_calloc( sizeof( monitor_entry_t ), 1 );
+
+	mp->mp_next = NULL;
+	mp->mp_children = NULL;
+	mp->mp_info = NULL;
+	mp->mp_flags = MONITOR_F_NONE;
+	mp->mp_cb = NULL;
+
+	ldap_pvt_thread_mutex_init( &mp->mp_mutex );
+
+	return mp;
+}
+
+Entry *
+monitor_entry_stub(
+	struct berval *pdn,
+	struct berval *pndn,
+	struct berval *rdn,
+	ObjectClass *oc,
+	struct berval *create,
+	struct berval *modify
+)
+{
+	monitor_info_t *mi;
+	AttributeDescription *nad = NULL;
+	Entry *e;
+	struct berval nat;
+	char *ptr;
+	const char *text;
+	int rc;
+
+	mi = ( monitor_info_t * )be_monitor->be_private;
+
+	nat = *rdn;
+	ptr = strchr( nat.bv_val, '=' );
+	nat.bv_len = ptr - nat.bv_val;
+	rc = slap_bv2ad( &nat, &nad, &text );
+	if ( rc )
+		return NULL;
+
+	e = entry_alloc();
+	if ( e ) {
+		struct berval nrdn;
+
+		rdnNormalize( 0, NULL, NULL, rdn, &nrdn, NULL );
+		build_new_dn( &e->e_name, pdn, rdn, NULL );
+		build_new_dn( &e->e_nname, pndn, &nrdn, NULL );
+		ber_memfree( nrdn.bv_val );
+		nat.bv_val = ptr + 1;
+		nat.bv_len = rdn->bv_len - ( nat.bv_val - rdn->bv_val );
+		attr_merge_normalize_one( e, slap_schema.si_ad_objectClass,
+			&oc->soc_cname, NULL );
+		attr_merge_normalize_one( e, slap_schema.si_ad_structuralObjectClass,
+			&oc->soc_cname, NULL );
+		attr_merge_normalize_one( e, nad, &nat, NULL );
+		attr_merge_one( e, slap_schema.si_ad_creatorsName, &mi->mi_creatorsName,
+			&mi->mi_ncreatorsName );
+		attr_merge_one( e, slap_schema.si_ad_modifiersName, &mi->mi_creatorsName,
+			&mi->mi_ncreatorsName );
+		attr_merge_normalize_one( e, slap_schema.si_ad_createTimestamp,
+			create ? create : &mi->mi_startTime, NULL );
+		attr_merge_normalize_one( e, slap_schema.si_ad_modifyTimestamp,
+			modify ? modify : &mi->mi_startTime, NULL );
+	}
+	return e;
+}
+
+Entry *
+monitor_entry_get_unlocked(
+	struct berval *ndn
+)
+{
+	monitor_info_t *mi = ( monitor_info_t * )be_monitor->be_private;
+	Entry *ret = NULL;
+
+	if ( !monitor_cache_get( mi, ndn, &ret ))
+		monitor_cache_release( mi, ret );
+	return ret;
+}
diff --git a/servers/slapd/back-monitor/init.c b/servers/slapd/back-monitor/init.c
new file mode 100644
index 0000000..af79fb4
--- /dev/null
+++ b/servers/slapd/back-monitor/init.c
@@ -0,0 +1,2567 @@
+/* init.c - initialize monitor backend */
+/* $OpenLDAP$ */
+/* This work is part of OpenLDAP Software <http://www.openldap.org/>.
+ *
+ * Copyright 2001-2022 The OpenLDAP Foundation.
+ * Portions Copyright 2001-2003 Pierangelo Masarati.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted only as authorized by the OpenLDAP
+ * Public License.
+ *
+ * A copy of this license is available in file LICENSE in the
+ * top-level directory of the distribution or, alternatively, at
+ * <http://www.OpenLDAP.org/license.html>.
+ */
+/* ACKNOWLEDGEMENTS:
+ * This work was initially developed by Pierangelo Masarati for inclusion
+ * in OpenLDAP Software.
+ */
+
+#include "portable.h"
+
+#include <stdio.h>
+#include <ac/string.h>
+
+#include <lutil.h>
+#include "slap.h"
+#include "slap-config.h"
+#include "lber_pvt.h"
+#include "back-monitor.h"
+
+#include "slap-config.h"
+
+#undef INTEGRATE_CORE_SCHEMA
+
+/*
+ * used by many functions to add description to entries
+ *
+ * WARNING: be_monitor may change as new databases are added,
+ * so it should not be used outside monitor_back_db_init()
+ * until monitor_back_db_open is called.
+ */
+BackendDB			*be_monitor;
+
+static struct monitor_subsys_t	**monitor_subsys;
+static int			monitor_subsys_opened;
+static monitor_info_t		monitor_info;
+static const monitor_extra_t monitor_extra = {
+	monitor_back_is_configured,
+	monitor_back_get_subsys,
+	monitor_back_get_subsys_by_dn,
+
+	monitor_back_register_subsys,
+	monitor_back_register_backend,
+	monitor_back_register_database,
+	monitor_back_register_overlay_info,
+	monitor_back_register_overlay,
+	monitor_back_register_entry,
+	monitor_back_register_entry_parent,
+	monitor_back_register_entry_attrs,
+	monitor_back_register_entry_callback,
+
+	monitor_back_unregister_entry,
+	monitor_back_unregister_entry_parent,
+	monitor_back_unregister_entry_attrs,
+	monitor_back_unregister_entry_callback,
+
+	monitor_back_entry_stub,
+	monitor_back_entrypriv_create,
+	monitor_back_register_subsys_late,
+	monitor_back_entry_get_unlocked
+};
+	
+
+/*
+ * subsystem data
+ *
+ * the known subsystems are added to the subsystems
+ * array at backend initialization; other subsystems
+ * may be added by calling monitor_back_register_subsys()
+ * before the database is opened (e.g. by other backends
+ * or by overlays or modules).
+ */
+static struct monitor_subsys_t known_monitor_subsys[] = {
+	{ 
+		SLAPD_MONITOR_BACKEND_NAME, 
+		BER_BVNULL, BER_BVNULL, BER_BVNULL,
+		{ BER_BVC( "This subsystem contains information about available backends." ),
+			BER_BVNULL },
+		MONITOR_F_PERSISTENT_CH,
+		monitor_subsys_backend_init,
+		NULL,	/* destroy */
+		NULL,   /* update */
+		NULL,   /* create */
+		NULL	/* modify */
+       	}, { 
+		SLAPD_MONITOR_CONN_NAME,
+		BER_BVNULL, BER_BVNULL, BER_BVNULL,
+		{ BER_BVC( "This subsystem contains information about connections." ),
+			BER_BVNULL },
+		MONITOR_F_VOLATILE_CH,
+		monitor_subsys_conn_init,
+		NULL,	/* destroy */
+		NULL,   /* update */
+		NULL,   /* create */
+		NULL	/* modify */
+       	}, { 
+		SLAPD_MONITOR_DATABASE_NAME, 	
+		BER_BVNULL, BER_BVNULL, BER_BVNULL,
+		{ BER_BVC( "This subsystem contains information about configured databases." ),
+			BER_BVNULL },
+		MONITOR_F_PERSISTENT_CH,
+		monitor_subsys_database_init,
+		NULL,	/* destroy */
+		NULL,   /* update */
+		NULL,   /* create */
+		NULL	/* modify */
+       	}, { 
+		SLAPD_MONITOR_LISTENER_NAME, 	
+		BER_BVNULL, BER_BVNULL, BER_BVNULL,
+		{ BER_BVC( "This subsystem contains information about active listeners." ),
+			BER_BVNULL },
+		MONITOR_F_PERSISTENT_CH,
+		monitor_subsys_listener_init,
+		NULL,	/* destroy */
+		NULL,	/* update */
+		NULL,	/* create */
+		NULL	/* modify */
+       	}, { 
+		SLAPD_MONITOR_LOG_NAME,
+		BER_BVNULL, BER_BVNULL, BER_BVNULL,
+		{ BER_BVC( "This subsystem contains information about logging." ),
+			BER_BVC( "Set the \"monitorLogLevel\" or \"monitorDebugLevel\" attributes to the desired levels." ),
+			BER_BVNULL },
+		MONITOR_F_NONE,
+		monitor_subsys_log_init,
+		NULL,	/* destroy */
+		NULL,	/* update */
+		NULL,   /* create */
+		NULL,	/* modify */
+       	}, { 
+		SLAPD_MONITOR_OPS_NAME,
+		BER_BVNULL, BER_BVNULL, BER_BVNULL,
+		{ BER_BVC( "This subsystem contains information about performed operations." ),
+			BER_BVNULL },
+		MONITOR_F_PERSISTENT_CH,
+		monitor_subsys_ops_init,
+		NULL,	/* destroy */
+		NULL,	/* update */
+		NULL,   /* create */
+		NULL,	/* modify */
+       	}, { 
+		SLAPD_MONITOR_OVERLAY_NAME,
+		BER_BVNULL, BER_BVNULL, BER_BVNULL,
+		{ BER_BVC( "This subsystem contains information about available overlays." ),
+			BER_BVNULL },
+		MONITOR_F_PERSISTENT_CH,
+		monitor_subsys_overlay_init,
+		NULL,	/* destroy */
+		NULL,	/* update */
+		NULL,   /* create */
+		NULL,	/* modify */
+	}, { 
+		SLAPD_MONITOR_SASL_NAME, 	
+		BER_BVNULL, BER_BVNULL, BER_BVNULL,
+		{ BER_BVC( "This subsystem contains information about SASL." ),
+			BER_BVNULL },
+		MONITOR_F_NONE,
+		NULL,   /* init */
+		NULL,	/* destroy */
+		NULL,   /* update */
+		NULL,   /* create */
+		NULL	/* modify */
+       	}, { 
+		SLAPD_MONITOR_SENT_NAME,
+		BER_BVNULL, BER_BVNULL, BER_BVNULL,
+		{ BER_BVC( "This subsystem contains statistics." ),
+			BER_BVNULL },
+		MONITOR_F_PERSISTENT_CH,
+		monitor_subsys_sent_init,
+		NULL,	/* destroy */
+		NULL,   /* update */
+		NULL,   /* create */
+		NULL,	/* modify */
+       	}, { 
+		SLAPD_MONITOR_THREAD_NAME, 	
+		BER_BVNULL, BER_BVNULL, BER_BVNULL,
+		{ BER_BVC( "This subsystem contains information about threads." ),
+			BER_BVNULL },
+		MONITOR_F_PERSISTENT_CH,
+		monitor_subsys_thread_init,
+		NULL,	/* destroy */
+		NULL,   /* update */
+		NULL,   /* create */
+		NULL	/* modify */
+       	}, { 
+		SLAPD_MONITOR_TIME_NAME,
+		BER_BVNULL, BER_BVNULL, BER_BVNULL,
+		{ BER_BVC( "This subsystem contains information about time." ),
+			BER_BVNULL },
+		MONITOR_F_PERSISTENT_CH,
+		monitor_subsys_time_init,
+		NULL,	/* destroy */
+		NULL,   /* update */
+		NULL,   /* create */
+		NULL,	/* modify */
+       	}, { 
+		SLAPD_MONITOR_TLS_NAME,
+		BER_BVNULL, BER_BVNULL, BER_BVNULL,
+		{ BER_BVC( "This subsystem contains information about TLS." ),
+			BER_BVNULL },
+		MONITOR_F_NONE,
+		NULL,   /* init */
+		NULL,	/* destroy */
+		NULL,   /* update */
+		NULL,   /* create */
+		NULL	/* modify */
+       	}, { 
+		SLAPD_MONITOR_RWW_NAME,
+		BER_BVNULL, BER_BVNULL, BER_BVNULL,
+		{ BER_BVC( "This subsystem contains information about read/write waiters." ),
+			BER_BVNULL },
+		MONITOR_F_PERSISTENT_CH,
+		monitor_subsys_rww_init,
+		NULL,	/* destroy */
+		NULL,   /* update */
+		NULL, 	/* create */
+		NULL	/* modify */
+       	}, { NULL }
+};
+
+int
+monitor_subsys_is_opened( void )
+{
+	return monitor_subsys_opened;
+}
+
+int
+monitor_back_register_subsys(
+	monitor_subsys_t	*ms )
+{
+	int	i = 0;
+
+	if ( monitor_subsys ) {
+		for ( ; monitor_subsys[ i ] != NULL; i++ )
+			/* just count'em */ ;
+	}
+
+	monitor_subsys = ch_realloc( monitor_subsys,
+			( 2 + i ) * sizeof( monitor_subsys_t * ) );
+
+	if ( monitor_subsys == NULL ) {
+		return -1;
+	}
+
+	monitor_subsys[ i ] = ms;
+	monitor_subsys[ i + 1 ] = NULL;
+
+	/* if a subsystem is registered __AFTER__ subsystem 
+	 * initialization (depending on the sequence the databases
+	 * are listed in slapd.conf), init it */
+	if ( monitor_subsys_is_opened() ) {
+
+		/* FIXME: this should only be possible
+		 * if be_monitor is already initialized */
+		assert( be_monitor != NULL );
+
+		if ( ms->mss_open && ( *ms->mss_open )( be_monitor, ms ) ) {
+			return -1;
+		}
+
+		ms->mss_flags |= MONITOR_F_OPENED;
+	}
+
+	return 0;
+}
+
+enum {
+	LIMBO_ENTRY,
+	LIMBO_ENTRY_PARENT,
+	LIMBO_ATTRS,
+	LIMBO_CB,
+	LIMBO_BACKEND,
+	LIMBO_DATABASE,
+	LIMBO_OVERLAY_INFO,
+	LIMBO_OVERLAY,
+	LIMBO_SUBSYS,
+
+	LIMBO_LAST
+};
+
+typedef struct entry_limbo_t {
+	int			el_type;
+	BackendInfo		*el_bi;
+	BackendDB		*el_be;
+	slap_overinst		*el_on;
+	Entry			*el_e;
+	Attribute		*el_a;
+	struct berval		*el_ndn;
+	struct berval		el_nbase;
+	int			el_scope;
+	struct berval		el_filter;
+	monitor_callback_t	*el_cb;
+	monitor_subsys_t	*el_mss;
+	unsigned long		el_flags;
+	struct entry_limbo_t	*el_next;
+} entry_limbo_t;
+
+int
+monitor_back_is_configured( void )
+{
+	return be_monitor != NULL;
+}
+
+int
+monitor_back_register_subsys_late(
+	monitor_subsys_t	*ms )
+{
+	entry_limbo_t	**elpp, el = { 0 };
+	monitor_info_t 	*mi;
+
+	if ( be_monitor == NULL ) {
+		Debug( LDAP_DEBUG_ANY,
+			"monitor_back_register_subsys_late: "
+			"monitor database not configured.\n" );
+		return -1;
+	}
+
+	/* everything is ready, can register already */
+	if ( monitor_subsys_is_opened() ) {
+		return monitor_back_register_subsys( ms );
+	}
+
+	mi = ( monitor_info_t * )be_monitor->be_private;
+
+
+	el.el_type = LIMBO_SUBSYS;
+
+	el.el_mss = ms;
+
+	for ( elpp = &mi->mi_entry_limbo;
+			*elpp;
+			elpp = &(*elpp)->el_next )
+		/* go to last */;
+
+	*elpp = (entry_limbo_t *)ch_malloc( sizeof( entry_limbo_t ) );
+
+	el.el_next = NULL;
+	**elpp = el;
+
+	return 0;
+}
+
+int
+monitor_back_register_backend(
+	BackendInfo		*bi )
+{
+	return -1;
+}
+
+int
+monitor_back_register_overlay_info(
+	slap_overinst		*on )
+{
+	return -1;
+}
+
+int
+monitor_back_register_backend_limbo(
+	BackendInfo		*bi )
+{
+	return -1;
+}
+
+int
+monitor_back_register_database_limbo(
+	BackendDB		*be,
+	struct berval		*ndn_out )
+{
+	entry_limbo_t	**elpp, el = { 0 };
+	monitor_info_t 	*mi;
+
+	if ( be_monitor == NULL ) {
+		Debug( LDAP_DEBUG_ANY,
+			"monitor_back_register_database_limbo: "
+			"monitor database not configured.\n" );
+		return -1;
+	}
+
+	mi = ( monitor_info_t * )be_monitor->be_private;
+
+
+	el.el_type = LIMBO_DATABASE;
+
+	el.el_be = be->bd_self;
+	el.el_ndn = ndn_out;
+	
+	for ( elpp = &mi->mi_entry_limbo;
+			*elpp;
+			elpp = &(*elpp)->el_next )
+		/* go to last */;
+
+	*elpp = (entry_limbo_t *)ch_malloc( sizeof( entry_limbo_t ) );
+
+	el.el_next = NULL;
+	**elpp = el;
+
+	return 0;
+}
+
+int
+monitor_back_register_overlay_info_limbo(
+	slap_overinst		*on )
+{
+	return -1;
+}
+
+int
+monitor_back_register_overlay_limbo(
+	BackendDB		*be,
+	struct slap_overinst	*on,
+	struct berval		*ndn_out )
+{
+	entry_limbo_t	**elpp, el = { 0 };
+	monitor_info_t 	*mi;
+
+	if ( be_monitor == NULL ) {
+		Debug( LDAP_DEBUG_ANY,
+			"monitor_back_register_overlay_limbo: "
+			"monitor database not configured.\n" );
+		return -1;
+	}
+
+	mi = ( monitor_info_t * )be_monitor->be_private;
+
+
+	el.el_type = LIMBO_OVERLAY;
+
+	el.el_be = be->bd_self;
+	el.el_on = on;
+	el.el_ndn = ndn_out;
+	
+	for ( elpp = &mi->mi_entry_limbo;
+			*elpp;
+			elpp = &(*elpp)->el_next )
+		/* go to last */;
+
+	*elpp = (entry_limbo_t *)ch_malloc( sizeof( entry_limbo_t ) );
+
+	el.el_next = NULL;
+	**elpp = el;
+
+	return 0;
+}
+
+int
+monitor_back_register_entry(
+	Entry			*e,
+	monitor_callback_t	*cb,
+	monitor_subsys_t	*mss,
+	unsigned long		flags )
+{
+	monitor_info_t 	*mi;
+	int rc = 0;
+
+	if ( be_monitor == NULL ) {
+		Debug( LDAP_DEBUG_ANY,
+			"monitor_back_register_entry(\"%s\"): "
+			"monitor database not configured.\n",
+			e->e_name.bv_val );
+		return -1;
+	}
+
+	mi = ( monitor_info_t * )be_monitor->be_private;
+
+	assert( mi != NULL );
+	assert( e != NULL );
+	assert( e->e_private == NULL );
+	
+	if ( monitor_subsys_is_opened() ) {
+		Entry		*e_parent = NULL, *e_new = NULL;
+		struct berval	pdn = BER_BVNULL;
+		monitor_entry_t *mp = NULL,
+				*mp_parent = NULL;
+
+		if ( monitor_cache_get( mi, &e->e_nname, &e_parent ) == 0 ) {
+			/* entry exists */
+			Debug( LDAP_DEBUG_ANY,
+				"monitor_back_register_entry(\"%s\"): "
+				"entry exists\n",
+				e->e_name.bv_val );
+			monitor_cache_release( mi, e_parent );
+			return -1;
+		}
+
+		dnParent( &e->e_nname, &pdn );
+		if ( monitor_cache_get( mi, &pdn, &e_parent ) != 0 ) {
+			/* parent does not exist */
+			Debug( LDAP_DEBUG_ANY,
+				"monitor_back_register_entry(\"%s\"): "
+				"parent \"%s\" not found\n",
+				e->e_name.bv_val, pdn.bv_val );
+			return -1;
+		}
+
+		assert( e_parent->e_private != NULL );
+		mp_parent = ( monitor_entry_t * )e_parent->e_private;
+
+		if ( mp_parent->mp_flags & MONITOR_F_VOLATILE ) {
+			/* entry is volatile; cannot append children */
+			Debug( LDAP_DEBUG_ANY,
+				"monitor_back_register_entry(\"%s\"): "
+				"parent \"%s\" is volatile\n",
+				e->e_name.bv_val, e_parent->e_name.bv_val );
+			rc = -1;
+			goto done;
+		}
+
+		mp = monitor_entrypriv_create();
+		if ( mp == NULL ) {
+			Debug( LDAP_DEBUG_ANY,
+				"monitor_back_register_entry(\"%s\"): "
+				"monitor_entrypriv_create() failed\n",
+				e->e_name.bv_val );
+			rc = -1;
+			goto done;
+		}
+
+		e_new = entry_dup( e );
+		if ( e_new == NULL ) {
+			Debug( LDAP_DEBUG_ANY,
+				"monitor_back_register_entry(\"%s\"): "
+				"entry_dup() failed\n",
+				e->e_name.bv_val );
+			rc = -1;
+			goto done;
+		}
+		
+		e_new->e_private = ( void * )mp;
+		if ( mss != NULL ) {
+			mp->mp_info = mss;
+			mp->mp_flags = flags;
+
+		} else {
+			mp->mp_info = mp_parent->mp_info;
+			mp->mp_flags = mp_parent->mp_flags | MONITOR_F_SUB;
+		}
+		mp->mp_cb = cb;
+
+		if ( monitor_cache_add( mi, e_new, e_parent ) ) {
+			Debug( LDAP_DEBUG_ANY,
+				"monitor_back_register_entry(\"%s\"): "
+				"unable to add entry\n",
+				e->e_name.bv_val );
+			rc = -1;
+			goto done;
+		}
+
+done:;
+		if ( rc ) {
+			if ( mp ) {
+				ch_free( mp );
+			}
+			if ( e_new ) {
+				e_new->e_private = NULL;
+				entry_free( e_new );
+			}
+		}
+
+		if ( e_parent ) {
+			monitor_cache_release( mi, e_parent );
+		}
+
+	} else {
+		entry_limbo_t	**elpp, el = { 0 };
+
+		el.el_type = LIMBO_ENTRY;
+
+		el.el_e = entry_dup( e );
+		if ( el.el_e == NULL ) {
+			Debug( LDAP_DEBUG_ANY,
+				"monitor_back_register_entry(\"%s\"): "
+				"entry_dup() failed\n",
+				e->e_name.bv_val );
+			return -1;
+		}
+		
+		el.el_cb = cb;
+		el.el_mss = mss;
+		el.el_flags = flags;
+
+		for ( elpp = &mi->mi_entry_limbo;
+				*elpp;
+				elpp = &(*elpp)->el_next )
+			/* go to last */;
+
+		*elpp = (entry_limbo_t *)ch_malloc( sizeof( entry_limbo_t ) );
+		if ( *elpp == NULL ) {
+			el.el_e->e_private = NULL;
+			entry_free( el.el_e );
+			return -1;
+		}
+
+		el.el_next = NULL;
+		**elpp = el;
+	}
+
+	return rc;
+}
+
+int
+monitor_back_register_entry_parent(
+	Entry			*e,
+	monitor_callback_t	*cb,
+	monitor_subsys_t	*mss,
+	unsigned long		flags,
+	struct berval		*nbase,
+	int			scope,
+	struct berval		*filter )
+{
+	monitor_info_t 	*mi;
+	struct berval	ndn = BER_BVNULL;
+
+	if ( be_monitor == NULL ) {
+		Debug( LDAP_DEBUG_ANY,
+			"monitor_back_register_entry_parent(base=\"%s\" scope=%s filter=\"%s\"): "
+			"monitor database not configured.\n",
+			BER_BVISNULL( nbase ) ? "" : nbase->bv_val,
+			ldap_pvt_scope2str( scope ),
+			BER_BVISNULL( filter ) ? "" : filter->bv_val );
+		return -1;
+	}
+
+	mi = ( monitor_info_t * )be_monitor->be_private;
+
+	assert( mi != NULL );
+	assert( e != NULL );
+	assert( e->e_private == NULL );
+
+	if ( BER_BVISNULL( filter ) ) {
+		/* need a filter */
+		Debug( LDAP_DEBUG_ANY,
+			"monitor_back_register_entry_parent(\"\"): "
+			"need a valid filter\n" );
+		return -1;
+	}
+
+	if ( monitor_subsys_is_opened() ) {
+		Entry		*e_parent = NULL, *e_new = NULL;
+		struct berval	e_name = BER_BVNULL,
+				e_nname = BER_BVNULL;
+		monitor_entry_t *mp = NULL,
+				*mp_parent = NULL;
+		int		rc = 0;
+
+		if ( monitor_search2ndn( nbase, scope, filter, &ndn ) ) {
+			/* entry does not exist */
+			Debug( LDAP_DEBUG_ANY,
+				"monitor_back_register_entry_parent(\"\"): "
+				"base=\"%s\" scope=%s filter=\"%s\": "
+				"unable to find entry\n",
+				nbase->bv_val ? nbase->bv_val : "\"\"",
+				ldap_pvt_scope2str( scope ),
+				filter->bv_val );
+			return -1;
+		}
+
+		if ( monitor_cache_get( mi, &ndn, &e_parent ) != 0 ) {
+			/* entry does not exist */
+			Debug( LDAP_DEBUG_ANY,
+				"monitor_back_register_entry_parent(\"%s\"): "
+				"parent entry does not exist\n",
+				ndn.bv_val );
+			rc = -1;
+			goto done;
+		}
+
+		assert( e_parent->e_private != NULL );
+		mp_parent = ( monitor_entry_t * )e_parent->e_private;
+
+		if ( mp_parent->mp_flags & MONITOR_F_VOLATILE ) {
+			/* entry is volatile; cannot append callback */
+			Debug( LDAP_DEBUG_ANY,
+				"monitor_back_register_entry_parent(\"%s\"): "
+				"entry is volatile\n",
+				e_parent->e_name.bv_val );
+			rc = -1;
+			goto done;
+		}
+
+		build_new_dn( &e_name, &e_parent->e_name, &e->e_name, NULL );
+		build_new_dn( &e_nname, &e_parent->e_nname, &e->e_nname, NULL );
+
+		if ( monitor_cache_get( mi, &e_nname, &e_new ) == 0 ) {
+			/* entry already exists */
+			Debug( LDAP_DEBUG_ANY,
+				"monitor_back_register_entry_parent(\"%s\"): "
+				"entry already exists\n",
+				e_name.bv_val );
+			monitor_cache_release( mi, e_new );
+			e_new = NULL;
+			rc = -1;
+			goto done;
+		}
+
+		mp = monitor_entrypriv_create();
+		if ( mp == NULL ) {
+			Debug( LDAP_DEBUG_ANY,
+				"monitor_back_register_entry_parent(\"%s\"): "
+				"monitor_entrypriv_create() failed\n",
+				e->e_name.bv_val );
+			rc = -1;
+			goto done;
+		}
+
+		e_new = entry_dup( e );
+		if ( e_new == NULL ) {
+			Debug( LDAP_DEBUG_ANY,
+				"monitor_back_register_entry(\"%s\"): "
+				"entry_dup() failed\n",
+				e->e_name.bv_val );
+			rc = -1;
+			goto done;
+		}
+		ch_free( e_new->e_name.bv_val );
+		ch_free( e_new->e_nname.bv_val );
+		e_new->e_name = e_name;
+		e_new->e_nname = e_nname;
+		
+		e_new->e_private = ( void * )mp;
+		if ( mss != NULL ) {
+			mp->mp_info = mss;
+			mp->mp_flags = flags;
+
+		} else {
+			mp->mp_info = mp_parent->mp_info;
+			mp->mp_flags = mp_parent->mp_flags | MONITOR_F_SUB;
+		}
+		mp->mp_cb = cb;
+
+		if ( monitor_cache_add( mi, e_new, e_parent ) ) {
+			Debug( LDAP_DEBUG_ANY,
+				"monitor_back_register_entry(\"%s\"): "
+				"unable to add entry\n",
+				e->e_name.bv_val );
+			rc = -1;
+			goto done;
+		}
+
+done:;
+		if ( !BER_BVISNULL( &ndn ) ) {
+			ch_free( ndn.bv_val );
+		}
+
+		if ( rc ) {
+			if ( mp ) {
+				ch_free( mp );
+			}
+			if ( e_new ) {
+				e_new->e_private = NULL;
+				entry_free( e_new );
+			}
+		}
+
+		if ( e_parent ) {
+			monitor_cache_release( mi, e_parent );
+		}
+
+	} else {
+		entry_limbo_t	**elpp = NULL, el = { 0 };
+
+		el.el_type = LIMBO_ENTRY_PARENT;
+
+		el.el_e = entry_dup( e );
+		if ( el.el_e == NULL ) {
+			Debug( LDAP_DEBUG_ANY,
+				"monitor_back_register_entry(\"%s\"): "
+				"entry_dup() failed\n",
+				e->e_name.bv_val );
+			goto done_limbo;
+		}
+		
+		if ( !BER_BVISNULL( nbase ) ) {
+			ber_dupbv( &el.el_nbase, nbase );
+		}
+
+		el.el_scope = scope;
+		if ( !BER_BVISNULL( filter ) ) {
+			ber_dupbv( &el.el_filter, filter  );
+		}
+
+		el.el_cb = cb;
+		el.el_mss = mss;
+		el.el_flags = flags;
+
+		for ( elpp = &mi->mi_entry_limbo;
+				*elpp;
+				elpp = &(*elpp)->el_next )
+			/* go to last */;
+
+		*elpp = (entry_limbo_t *)ch_malloc( sizeof( entry_limbo_t ) );
+		if ( *elpp == NULL ) {
+			goto done_limbo;
+		}
+
+done_limbo:;
+		if ( *elpp != NULL ) {
+			el.el_next = NULL;
+			**elpp = el;
+
+		} else {
+			if ( !BER_BVISNULL( &el.el_filter ) ) {
+				ch_free( el.el_filter.bv_val );
+			}
+			if ( !BER_BVISNULL( &el.el_nbase ) ) {
+				ch_free( el.el_nbase.bv_val );
+			}
+			entry_free( el.el_e );
+			return -1;
+		}
+	}
+
+	return 0;
+}
+
+static int
+monitor_search2ndn_cb( Operation *op, SlapReply *rs )
+{
+	if ( rs->sr_type == REP_SEARCH ) {
+		struct berval	*ndn = op->o_callback->sc_private;
+
+		if ( !BER_BVISNULL( ndn ) ) {
+			rs->sr_err = LDAP_SIZELIMIT_EXCEEDED;
+			ch_free( ndn->bv_val );
+			BER_BVZERO( ndn );
+			return rs->sr_err;
+		}
+		
+		ber_dupbv( ndn, &rs->sr_entry->e_nname );
+	}
+
+	return 0;
+}
+
+int
+monitor_search2ndn(
+	struct berval	*nbase,
+	int		scope,
+	struct berval	*filter,
+	struct berval	*ndn )
+{
+	Connection	conn = { 0 };
+	OperationBuffer	opbuf;
+	Operation	*op;
+	void	*thrctx;
+	SlapReply	rs = { REP_RESULT };
+	slap_callback	cb = { NULL, monitor_search2ndn_cb, NULL, NULL };
+	int		rc;
+
+	BER_BVZERO( ndn );
+
+	if ( be_monitor == NULL ) {
+		return -1;
+	}
+
+	thrctx = ldap_pvt_thread_pool_context();
+	connection_fake_init2( &conn, &opbuf, thrctx, 0 );
+	op = &opbuf.ob_op;
+
+	op->o_tag = LDAP_REQ_SEARCH;
+
+	/* use global malloc for now */
+	if ( op->o_tmpmemctx ) {
+		op->o_tmpmemctx = NULL;
+	}
+	op->o_tmpmfuncs = &ch_mfuncs;
+
+	op->o_bd = be_monitor;
+	if ( nbase == NULL || BER_BVISNULL( nbase ) ) {
+		ber_dupbv_x( &op->o_req_dn, &op->o_bd->be_suffix[ 0 ],
+				op->o_tmpmemctx );
+		ber_dupbv_x( &op->o_req_ndn, &op->o_bd->be_nsuffix[ 0 ],
+				op->o_tmpmemctx );
+
+	} else {
+		if ( dnPrettyNormal( NULL, nbase, &op->o_req_dn, &op->o_req_ndn,
+					op->o_tmpmemctx ) ) {
+			return -1;
+		}
+	}
+
+	op->o_callback = &cb;
+	cb.sc_private = (void *)ndn;
+
+	op->ors_scope = scope;
+	op->ors_filter = str2filter_x( op, filter->bv_val );
+	if ( op->ors_filter == NULL ) {
+		rc = LDAP_OTHER;
+		goto cleanup;
+	}
+	ber_dupbv_x( &op->ors_filterstr, filter, op->o_tmpmemctx );
+	op->ors_attrs = slap_anlist_no_attrs;
+	op->ors_attrsonly = 0;
+	op->ors_tlimit = SLAP_NO_LIMIT;
+	op->ors_slimit = 1;
+	op->ors_limit = NULL;
+	op->ors_deref = LDAP_DEREF_NEVER;
+
+	op->o_nocaching = 1;
+	op->o_managedsait = SLAP_CONTROL_NONCRITICAL;
+
+	op->o_dn = be_monitor->be_rootdn;
+	op->o_ndn = be_monitor->be_rootndn;
+
+	rc = op->o_bd->be_search( op, &rs );
+
+cleanup:;
+	if ( op->ors_filter != NULL ) {
+		filter_free_x( op, op->ors_filter, 1 );
+	}
+	if ( !BER_BVISNULL( &op->ors_filterstr ) ) {
+		op->o_tmpfree( op->ors_filterstr.bv_val, op->o_tmpmemctx );
+	}
+	if ( !BER_BVISNULL( &op->o_req_dn ) ) {
+		op->o_tmpfree( op->o_req_dn.bv_val, op->o_tmpmemctx );
+	}
+	if ( !BER_BVISNULL( &op->o_req_ndn ) ) {
+		op->o_tmpfree( op->o_req_ndn.bv_val, op->o_tmpmemctx );
+	}
+
+	if ( rc != 0 ) {
+		return rc;
+	}
+
+	switch ( rs.sr_err ) {
+	case LDAP_SUCCESS:
+		if ( BER_BVISNULL( ndn ) ) {
+			rc = -1;
+		}
+		break;
+			
+	case LDAP_SIZELIMIT_EXCEEDED:
+	default:
+		if ( !BER_BVISNULL( ndn ) ) {
+			ber_memfree( ndn->bv_val );
+			BER_BVZERO( ndn );
+		}
+		rc = -1;
+		break;
+	}
+
+	return rc;
+}
+
+int
+monitor_back_register_entry_attrs(
+	struct berval		*ndn_in,
+	Attribute		*a,
+	monitor_callback_t	*cb,
+	struct berval		*nbase,
+	int			scope,
+	struct berval		*filter )
+{
+	monitor_info_t 	*mi;
+	struct berval	ndn = BER_BVNULL;
+	char		*fname = ( a == NULL ? "callback" : "attrs" );
+	struct berval	empty_bv = BER_BVC("");
+
+	if ( nbase == NULL ) nbase = &empty_bv;
+	if ( filter == NULL ) filter = &empty_bv;
+
+	if ( be_monitor == NULL ) {
+		Debug(LDAP_DEBUG_ANY,
+		      "monitor_back_register_entry_%s(base=\"%s\" scope=%s filter=\"%s\"): " "monitor database not configured.\n\n",
+		      fname, BER_BVISNULL(nbase) ? "" : nbase->bv_val,
+		      ldap_pvt_scope2str(scope),
+		      BER_BVISNULL(filter) ? "" : filter->bv_val );
+
+		return -1;
+	}
+
+	mi = ( monitor_info_t * )be_monitor->be_private;
+
+	assert( mi != NULL );
+
+	if ( ndn_in != NULL ) {
+		ndn = *ndn_in;
+	}
+
+	if ( a == NULL && cb == NULL ) {
+		/* nothing to do */
+		return -1;
+	}
+
+	if ( ( ndn_in == NULL || BER_BVISNULL( &ndn ) )
+			&& BER_BVISNULL( filter ) )
+	{
+		/* need a filter */
+		Debug( LDAP_DEBUG_ANY,
+			"monitor_back_register_entry_%s(\"\"): "
+			"need a valid filter\n",
+			fname );
+		return -1;
+	}
+
+	if ( monitor_subsys_is_opened() ) {
+		Entry			*e = NULL;
+		Attribute		**atp = NULL;
+		monitor_entry_t 	*mp = NULL;
+		monitor_callback_t	**mcp = NULL;
+		int			rc = 0;
+		int			freeit = 0;
+
+		if ( BER_BVISNULL( &ndn ) ) {
+			if ( monitor_search2ndn( nbase, scope, filter, &ndn ) ) {
+				Debug(LDAP_DEBUG_ANY,
+				      "monitor_back_register_entry_%s(\"\"): " "base=\"%s\" scope=%s filter=\"%s\": " "unable to find entry\n\n",
+				      fname,
+				      nbase->bv_val ? nbase->bv_val : "\"\"",
+				      ldap_pvt_scope2str(scope),
+				      filter->bv_val );
+				return -1;
+			}
+
+			freeit = 1;
+		}
+
+		if ( monitor_cache_get( mi, &ndn, &e ) != 0 ) {
+			/* entry does not exist */
+			Debug( LDAP_DEBUG_ANY,
+				"monitor_back_register_entry_%s(\"%s\"): "
+				"entry does not exist\n",
+				fname, ndn.bv_val );
+			rc = -1;
+			goto done;
+		}
+
+		assert( e->e_private != NULL );
+		mp = ( monitor_entry_t * )e->e_private;
+
+		if ( mp->mp_flags & MONITOR_F_VOLATILE ) {
+			/* entry is volatile; cannot append callback */
+			Debug( LDAP_DEBUG_ANY,
+				"monitor_back_register_entry_%s(\"%s\"): "
+				"entry is volatile\n",
+				fname, e->e_name.bv_val );
+			rc = -1;
+			goto done;
+		}
+
+		if ( a ) {
+			for ( atp = &e->e_attrs; *atp; atp = &(*atp)->a_next )
+				/* just get to last */ ;
+
+			for ( ; a != NULL; a = a->a_next ) {
+				assert( a->a_desc != NULL );
+				assert( a->a_vals != NULL );
+
+				if ( attr_find( e->e_attrs, a->a_desc ) ) {
+					attr_merge( e, a->a_desc, a->a_vals,
+						a->a_nvals == a->a_vals ? NULL : a->a_nvals );
+
+				} else {
+					*atp = attr_dup( a );
+					if ( *atp == NULL ) {
+						Debug( LDAP_DEBUG_ANY,
+							"monitor_back_register_entry_%s(\"%s\"): "
+							"attr_dup() failed\n",
+							fname, e->e_name.bv_val );
+						rc = -1;
+						goto done;
+					}
+					atp = &(*atp)->a_next;
+				}
+			}
+		}
+
+		if ( cb ) {
+			for ( mcp = &mp->mp_cb; *mcp; mcp = &(*mcp)->mc_next )
+				/* go to tail */ ;
+		
+			/* NOTE: we do not clear cb->mc_next, so this function
+			 * can be used to append a list of callbacks */
+			(*mcp) = cb;
+		}
+
+done:;
+		if ( rc ) {
+			if ( atp && *atp ) {
+				attrs_free( *atp );
+				*atp = NULL;
+			}
+		}
+
+		if ( freeit ) {
+			ber_memfree( ndn.bv_val );
+		}
+
+		if ( e ) {
+			monitor_cache_release( mi, e );
+		}
+
+	} else {
+		entry_limbo_t	**elpp, el = { 0 };
+
+		el.el_type = LIMBO_ATTRS;
+		el.el_ndn = ndn_in;
+		if ( !BER_BVISNULL( nbase ) ) {
+			ber_dupbv( &el.el_nbase, nbase);
+		}
+		el.el_scope = scope;
+		if ( !BER_BVISNULL( filter ) ) {
+			ber_dupbv( &el.el_filter, filter  );
+		}
+
+		el.el_a = attrs_dup( a );
+		el.el_cb = cb;
+
+		for ( elpp = &mi->mi_entry_limbo;
+				*elpp;
+				elpp = &(*elpp)->el_next )
+			/* go to last */;
+
+		*elpp = (entry_limbo_t *)ch_malloc( sizeof( entry_limbo_t ) );
+		if ( *elpp == NULL ) {
+			if ( !BER_BVISNULL( &el.el_filter ) ) {
+				ch_free( el.el_filter.bv_val );
+			}
+			if ( el.el_a != NULL ) {
+				attrs_free( el.el_a );
+			}
+			if ( !BER_BVISNULL( &el.el_nbase ) ) {
+				ch_free( &el.el_nbase.bv_val );
+			}
+			return -1;
+		}
+
+		el.el_next = NULL;
+		**elpp = el;
+	}
+
+	return 0;
+}
+
+int
+monitor_back_register_entry_callback(
+	struct berval		*ndn,
+	monitor_callback_t	*cb,
+	struct berval		*nbase,
+	int			scope,
+	struct berval		*filter )
+{
+	return monitor_back_register_entry_attrs( ndn, NULL, cb,
+			nbase, scope, filter );
+}
+
+/*
+ * TODO: add corresponding calls to remove installed callbacks, entries
+ * and so, in case the entity that installed them is removed (e.g. a 
+ * database, via back-config)
+ */
+int
+monitor_back_unregister_entry(
+	struct berval	*ndn )
+{
+	monitor_info_t 	*mi;
+
+	if ( be_monitor == NULL ) {
+		Debug( LDAP_DEBUG_ANY,
+			"monitor_back_unregister_entry(\"%s\"): "
+			"monitor database not configured.\n",
+			ndn->bv_val );
+
+		return -1;
+	}
+
+	/* entry will be regularly freed, and resources released
+	 * according to callbacks */
+	if ( slapd_shutdown ) {
+		return 0;
+	}
+
+	mi = ( monitor_info_t * )be_monitor->be_private;
+
+	assert( mi != NULL );
+
+	if ( monitor_subsys_is_opened() ) {
+		Entry			*e = NULL;
+		monitor_entry_t 	*mp = NULL;
+		monitor_callback_t	*cb = NULL;
+
+		if ( monitor_cache_remove( mi, ndn, &e ) != 0 ) {
+			/* entry does not exist */
+			Debug( LDAP_DEBUG_ANY,
+				"monitor_back_unregister_entry(\"%s\"): "
+				"entry removal failed.\n",
+				ndn->bv_val );
+			return -1;
+		}
+
+		mp = (monitor_entry_t *)e->e_private;
+		assert( mp != NULL );
+
+		for ( cb = mp->mp_cb; cb != NULL; ) {
+			monitor_callback_t	*next = cb->mc_next;
+
+			if ( cb->mc_free ) {
+				(void)cb->mc_free( e, &cb->mc_private );
+			}
+			ch_free( cb );
+
+			cb = next;
+		}
+
+		ch_free( mp );
+		e->e_private = NULL;
+		entry_free( e );
+
+	} else {
+		entry_limbo_t	**elpp;
+
+		for ( elpp = &mi->mi_entry_limbo;
+			*elpp;
+			elpp = &(*elpp)->el_next )
+		{
+			entry_limbo_t	*elp = *elpp;
+
+			if ( elp->el_type == LIMBO_ENTRY
+				&& dn_match( ndn, &elp->el_e->e_nname ) )
+			{
+				monitor_callback_t	*cb, *next;
+
+				for ( cb = elp->el_cb; cb; cb = next ) {
+					/* FIXME: call callbacks? */
+					next = cb->mc_next;
+					if ( cb->mc_dispose ) {
+						cb->mc_dispose( &cb->mc_private );
+					}
+					ch_free( cb );
+				}
+				assert( elp->el_e != NULL );
+				elp->el_e->e_private = NULL;
+				entry_free( elp->el_e );
+				*elpp = elp->el_next;
+				ch_free( elp );
+				elpp = NULL;
+				break;
+			}
+		}
+
+		if ( elpp != NULL ) {
+			/* not found!  where did it go? */
+			return 1;
+		}
+	}
+
+	return 0;
+}
+
+int
+monitor_back_unregister_entry_parent(
+	struct berval		*nrdn,
+	monitor_callback_t	*target_cb,
+	struct berval		*nbase,
+	int			scope,
+	struct berval		*filter )
+{
+	monitor_info_t 	*mi;
+	struct berval	ndn = BER_BVNULL;
+
+	if ( be_monitor == NULL ) {
+		Debug( LDAP_DEBUG_ANY,
+			"monitor_back_unregister_entry_parent(base=\"%s\" scope=%s filter=\"%s\"): "
+			"monitor database not configured.\n",
+			BER_BVISNULL( nbase ) ? "" : nbase->bv_val,
+			ldap_pvt_scope2str( scope ),
+			BER_BVISNULL( filter ) ? "" : filter->bv_val );
+
+		return -1;
+	}
+
+	/* entry will be regularly freed, and resources released
+	 * according to callbacks */
+	if ( slapd_shutdown ) {
+		return 0;
+	}
+
+	mi = ( monitor_info_t * )be_monitor->be_private;
+
+	assert( mi != NULL );
+
+	if ( ( nrdn == NULL || BER_BVISNULL( nrdn ) )
+			&& BER_BVISNULL( filter ) )
+	{
+		/* need a filter */
+		Debug( LDAP_DEBUG_ANY,
+			"monitor_back_unregister_entry_parent(\"\"): "
+			"need a valid filter\n" );
+		return -1;
+	}
+
+	if ( monitor_subsys_is_opened() ) {
+		Entry			*e = NULL;
+		monitor_entry_t 	*mp = NULL;
+
+		if ( monitor_search2ndn( nbase, scope, filter, &ndn ) ) {
+			/* entry does not exist */
+			Debug( LDAP_DEBUG_ANY,
+				"monitor_back_unregister_entry_parent(\"\"): "
+				"base=\"%s\" scope=%s filter=\"%s\": "
+				"unable to find entry\n",
+				nbase->bv_val ? nbase->bv_val : "\"\"",
+				ldap_pvt_scope2str( scope ),
+				filter->bv_val );
+			return -1;
+		}
+
+		if ( monitor_cache_remove( mi, &ndn, &e ) != 0 ) {
+			/* entry does not exist */
+			Debug( LDAP_DEBUG_ANY,
+				"monitor_back_unregister_entry(\"%s\"): "
+				"entry removal failed.\n",
+				ndn.bv_val );
+			ber_memfree( ndn.bv_val );
+			return -1;
+		}
+		ber_memfree( ndn.bv_val );
+
+		mp = (monitor_entry_t *)e->e_private;
+		assert( mp != NULL );
+
+		if ( target_cb != NULL ) {
+			monitor_callback_t	**cbp;
+
+			for ( cbp = &mp->mp_cb; *cbp != NULL; cbp = &(*cbp)->mc_next ) {
+				if ( *cbp == target_cb ) {
+					if ( (*cbp)->mc_free ) {
+						(void)(*cbp)->mc_free( e, &(*cbp)->mc_private );
+					}
+					*cbp = (*cbp)->mc_next;
+					ch_free( target_cb );
+					break;
+				}
+			}
+		}
+
+
+		ch_free( mp );
+		e->e_private = NULL;
+		entry_free( e );
+
+	} else {
+		entry_limbo_t	**elpp;
+
+		for ( elpp = &mi->mi_entry_limbo;
+			*elpp;
+			elpp = &(*elpp)->el_next )
+		{
+			entry_limbo_t	*elp = *elpp;
+
+			if ( elp->el_type == LIMBO_ENTRY_PARENT
+				&& dn_match( nrdn, &elp->el_e->e_nname )
+				&& dn_match( nbase, &elp->el_nbase )
+				&& scope == elp->el_scope
+				&& bvmatch( filter, &elp->el_filter ) )
+			{
+				monitor_callback_t	*cb, *next;
+
+				for ( cb = elp->el_cb; cb; cb = next ) {
+					/* FIXME: call callbacks? */
+					next = cb->mc_next;
+					if ( cb->mc_dispose ) {
+						cb->mc_dispose( &cb->mc_private );
+					}
+					ch_free( cb );
+				}
+				assert( elp->el_e != NULL );
+				elp->el_e->e_private = NULL;
+				entry_free( elp->el_e );
+				if ( !BER_BVISNULL( &elp->el_nbase ) ) {
+					ch_free( elp->el_nbase.bv_val );
+				}
+				if ( !BER_BVISNULL( &elp->el_filter ) ) {
+					ch_free( elp->el_filter.bv_val );
+				}
+				*elpp = elp->el_next;
+				ch_free( elp );
+				elpp = NULL;
+				break;
+			}
+		}
+
+		if ( elpp != NULL ) {
+			/* not found!  where did it go? */
+			return 1;
+		}
+	}
+
+	return 0;
+}
+
+int
+monitor_back_unregister_entry_attrs(
+	struct berval		*ndn_in,
+	Attribute		*target_a,
+	monitor_callback_t	*target_cb,
+	struct berval		*nbase,
+	int			scope,
+	struct berval		*filter )
+{
+	monitor_info_t 	*mi;
+	struct berval	ndn = BER_BVNULL;
+	char		*fname = ( target_a == NULL ? "callback" : "attrs" );
+
+	if ( be_monitor == NULL ) {
+		Debug(LDAP_DEBUG_ANY,
+		      "monitor_back_unregister_entry_%s(base=\"%s\" scope=%s filter=\"%s\"): " "monitor database not configured.\n\n",
+		      fname, BER_BVISNULL(nbase) ? "" : nbase->bv_val,
+		      ldap_pvt_scope2str(scope),
+		      BER_BVISNULL(filter) ? "" : filter->bv_val );
+
+		return -1;
+	}
+
+	/* entry will be regularly freed, and resources released
+	 * according to callbacks */
+	if ( slapd_shutdown ) {
+		return 0;
+	}
+
+	mi = ( monitor_info_t * )be_monitor->be_private;
+
+	assert( mi != NULL );
+
+	if ( ndn_in != NULL ) {
+		ndn = *ndn_in;
+	}
+
+	if ( target_a == NULL && target_cb == NULL ) {
+		/* nothing to do */
+		return -1;
+	}
+
+	if ( ( ndn_in == NULL || BER_BVISNULL( &ndn ) )
+			&& BER_BVISNULL( filter ) )
+	{
+		/* need a filter */
+		Debug( LDAP_DEBUG_ANY,
+			"monitor_back_unregister_entry_%s(\"\"): "
+			"need a valid filter\n",
+			fname );
+		return -1;
+	}
+
+	if ( monitor_subsys_is_opened() ) {
+		Entry			*e = NULL;
+		monitor_entry_t 	*mp = NULL;
+		int			freeit = 0;
+
+		if ( BER_BVISNULL( &ndn ) ) {
+			if ( monitor_search2ndn( nbase, scope, filter, &ndn ) ) {
+				Debug(LDAP_DEBUG_ANY,
+				      "monitor_back_unregister_entry_%s(\"\"): " "base=\"%s\" scope=%d filter=\"%s\": " "unable to find entry\n\n",
+				      fname,
+				      nbase->bv_val ? nbase->bv_val : "\"\"",
+				      scope, filter->bv_val );
+				return -1;
+			}
+
+			freeit = 1;
+		}
+
+		if ( monitor_cache_get( mi, &ndn, &e ) != 0 ) {
+			/* entry does not exist */
+			Debug( LDAP_DEBUG_ANY,
+				"monitor_back_unregister_entry(\"%s\"): "
+				"entry removal failed.\n",
+				ndn.bv_val );
+			return -1;
+		}
+
+		mp = (monitor_entry_t *)e->e_private;
+		assert( mp != NULL );
+
+		if ( target_cb != NULL ) {
+			monitor_callback_t	**cbp;
+
+			for ( cbp = &mp->mp_cb; *cbp != NULL; cbp = &(*cbp)->mc_next ) {
+				if ( *cbp == target_cb ) {
+					if ( (*cbp)->mc_free ) {
+						(void)(*cbp)->mc_free( e, &(*cbp)->mc_private );
+					}
+					*cbp = (*cbp)->mc_next;
+					ch_free( target_cb );
+					break;
+				}
+			}
+		}
+
+		if ( target_a != NULL ) {
+			Attribute	*a;
+
+			for ( a = target_a; a != NULL; a = a->a_next ) {
+				Modification	mod = { 0 };
+				const char	*text;
+				char		textbuf[ SLAP_TEXT_BUFLEN ];
+
+				mod.sm_op = LDAP_MOD_DELETE;
+				mod.sm_desc = a->a_desc;
+				mod.sm_values = a->a_vals;
+				mod.sm_nvalues = a->a_nvals;
+
+				(void)modify_delete_values( e, &mod, 1,
+					&text, textbuf, sizeof( textbuf ) );
+			}
+		}
+
+		if ( freeit ) {
+			ber_memfree( ndn.bv_val );
+		}
+
+		monitor_cache_release( mi, e );
+
+	} else {
+		entry_limbo_t	**elpp;
+
+		for ( elpp = &mi->mi_entry_limbo;
+			*elpp;
+			elpp = &(*elpp)->el_next )
+		{
+			entry_limbo_t	*elp = *elpp;
+
+			if ( elp->el_type == LIMBO_ATTRS
+				&& dn_match( nbase, &elp->el_nbase )
+				&& scope == elp->el_scope
+				&& bvmatch( filter, &elp->el_filter ) )
+			{
+				monitor_callback_t	*cb, *next;
+
+				for ( cb = elp->el_cb; cb; cb = next ) {
+					/* FIXME: call callbacks? */
+					next = cb->mc_next;
+					if ( cb->mc_dispose ) {
+						cb->mc_dispose( &cb->mc_private );
+					}
+					ch_free( cb );
+				}
+				assert( elp->el_e == NULL );
+				if ( elp->el_a != NULL ) {
+					attrs_free( elp->el_a );
+				}
+				if ( !BER_BVISNULL( &elp->el_nbase ) ) {
+					ch_free( elp->el_nbase.bv_val );
+				}
+				if ( !BER_BVISNULL( &elp->el_filter ) ) {
+					ch_free( elp->el_filter.bv_val );
+				}
+				*elpp = elp->el_next;
+				ch_free( elp );
+				elpp = NULL;
+				break;
+			}
+		}
+
+		if ( elpp != NULL ) {
+			/* not found!  where did it go? */
+			return 1;
+		}
+	}
+
+	return 0;
+}
+
+int
+monitor_back_unregister_entry_callback(
+	struct berval		*ndn,
+	monitor_callback_t	*cb,
+	struct berval		*nbase,
+	int			scope,
+	struct berval		*filter )
+{
+	/* TODO: lookup entry (by ndn, if not NULL, and/or by callback);
+	 * unregister the callback; if a is not null, unregister the
+	 * given attrs.  In any case, call cb->cb_free */
+	return monitor_back_unregister_entry_attrs( ndn,
+		NULL, cb, nbase, scope, filter );
+}
+
+monitor_subsys_t *
+monitor_back_get_subsys( const char *name )
+{
+	if ( monitor_subsys != NULL ) {
+		int	i;
+		
+		for ( i = 0; monitor_subsys[ i ] != NULL; i++ ) {
+			if ( strcasecmp( monitor_subsys[ i ]->mss_name, name ) == 0 ) {
+				return monitor_subsys[ i ];
+			}
+		}
+	}
+
+	return NULL;
+}
+
+monitor_subsys_t *
+monitor_back_get_subsys_by_dn(
+	struct berval	*ndn,
+	int		sub )
+{
+	if ( monitor_subsys != NULL ) {
+		int	i;
+
+		if ( sub ) {
+			for ( i = 0; monitor_subsys[ i ] != NULL; i++ ) {
+				if ( dnIsSuffix( ndn, &monitor_subsys[ i ]->mss_ndn ) ) {
+					return monitor_subsys[ i ];
+				}
+			}
+
+		} else {
+			for ( i = 0; monitor_subsys[ i ] != NULL; i++ ) {
+				if ( dn_match( ndn, &monitor_subsys[ i ]->mss_ndn ) ) {
+					return monitor_subsys[ i ];
+				}
+			}
+		}
+	}
+
+	return NULL;
+}
+
+int
+monitor_back_initialize(
+	BackendInfo	*bi )
+{
+	static char		*controls[] = {
+		LDAP_CONTROL_MANAGEDSAIT,
+		NULL
+	};
+
+	static ConfigTable monitorcfg[] = {
+		{ NULL, NULL, 0, 0, 0, ARG_IGNORED,
+			NULL, NULL, NULL, NULL }
+	};
+
+	static ConfigOCs monitorocs[] = {
+		{ "( OLcfgDbOc:4.1 "
+			"NAME 'olcMonitorConfig' "
+			"DESC 'Monitor backend configuration' "
+			"SUP olcDatabaseConfig "
+			")",
+			 	Cft_Database, monitorcfg },
+		{ NULL, 0, NULL }
+	};
+
+	struct m_s {
+		char	*schema;
+		slap_mask_t flags;
+		int	offset;
+	} moc[] = {
+		{ "( 1.3.6.1.4.1.4203.666.3.16.1 "
+			"NAME 'monitor' "
+			"DESC 'OpenLDAP system monitoring' "
+			"SUP top STRUCTURAL "
+			"MUST cn "
+			"MAY ( "
+				"description "
+				"$ seeAlso "
+				"$ labeledURI "
+				"$ monitoredInfo "
+				"$ managedInfo "
+				"$ monitorOverlay "
+			") )", SLAP_OC_OPERATIONAL|SLAP_OC_HIDE,
+			offsetof(monitor_info_t, mi_oc_monitor) },
+		{ "( 1.3.6.1.4.1.4203.666.3.16.2 "
+			"NAME 'monitorServer' "
+			"DESC 'Server monitoring root entry' "
+			"SUP monitor STRUCTURAL )", SLAP_OC_OPERATIONAL|SLAP_OC_HIDE,
+			offsetof(monitor_info_t, mi_oc_monitorServer) },
+		{ "( 1.3.6.1.4.1.4203.666.3.16.3 "
+			"NAME 'monitorContainer' "
+			"DESC 'monitor container class' "
+			"SUP monitor STRUCTURAL )", SLAP_OC_OPERATIONAL|SLAP_OC_HIDE,
+			offsetof(monitor_info_t, mi_oc_monitorContainer) },
+		{ "( 1.3.6.1.4.1.4203.666.3.16.4 "
+			"NAME 'monitorCounterObject' "
+			"DESC 'monitor counter class' "
+			"SUP monitor STRUCTURAL )", SLAP_OC_OPERATIONAL|SLAP_OC_HIDE,
+			offsetof(monitor_info_t, mi_oc_monitorCounterObject) },
+		{ "( 1.3.6.1.4.1.4203.666.3.16.5 "
+			"NAME 'monitorOperation' "
+			"DESC 'monitor operation class' "
+			"SUP monitor STRUCTURAL )", SLAP_OC_OPERATIONAL|SLAP_OC_HIDE,
+			offsetof(monitor_info_t, mi_oc_monitorOperation) },
+		{ "( 1.3.6.1.4.1.4203.666.3.16.6 "
+			"NAME 'monitorConnection' "
+			"DESC 'monitor connection class' "
+			"SUP monitor STRUCTURAL )", SLAP_OC_OPERATIONAL|SLAP_OC_HIDE,
+			offsetof(monitor_info_t, mi_oc_monitorConnection) },
+		{ "( 1.3.6.1.4.1.4203.666.3.16.7 "
+			"NAME 'managedObject' "
+			"DESC 'monitor managed entity class' "
+			"SUP monitor STRUCTURAL )", SLAP_OC_OPERATIONAL|SLAP_OC_HIDE,
+			offsetof(monitor_info_t, mi_oc_managedObject) },
+		{ "( 1.3.6.1.4.1.4203.666.3.16.8 "
+			"NAME 'monitoredObject' "
+			"DESC 'monitor monitored entity class' "
+			"SUP monitor STRUCTURAL )", SLAP_OC_OPERATIONAL|SLAP_OC_HIDE,
+			offsetof(monitor_info_t, mi_oc_monitoredObject) },
+		{ NULL, 0, -1 }
+	}, mat[] = {
+		{ "( 1.3.6.1.4.1.4203.666.1.55.1 "
+			"NAME 'monitoredInfo' "
+			"DESC 'monitored info' "
+			/* "SUP name " */
+			"EQUALITY caseIgnoreMatch "
+			"SUBSTR caseIgnoreSubstringsMatch "
+			"SYNTAX 1.3.6.1.4.1.1466.115.121.1.15{32768} "
+			"NO-USER-MODIFICATION "
+			"USAGE dSAOperation )", SLAP_AT_HIDE,
+			offsetof(monitor_info_t, mi_ad_monitoredInfo) },
+		{ "( 1.3.6.1.4.1.4203.666.1.55.2 "
+			"NAME 'managedInfo' "
+			"DESC 'monitor managed info' "
+			"SUP name )", SLAP_AT_HIDE,
+			offsetof(monitor_info_t, mi_ad_managedInfo) },
+		{ "( 1.3.6.1.4.1.4203.666.1.55.3 "
+			"NAME 'monitorCounter' "
+			"DESC 'monitor counter' "
+			"EQUALITY integerMatch "
+			"ORDERING integerOrderingMatch "
+			"SYNTAX 1.3.6.1.4.1.1466.115.121.1.27 "
+			"NO-USER-MODIFICATION "
+			"USAGE dSAOperation )", SLAP_AT_HIDE,
+			offsetof(monitor_info_t, mi_ad_monitorCounter) },
+		{ "( 1.3.6.1.4.1.4203.666.1.55.4 "
+			"NAME 'monitorOpCompleted' "
+			"DESC 'monitor completed operations' "
+			"SUP monitorCounter "
+			"NO-USER-MODIFICATION "
+			"USAGE dSAOperation )", SLAP_AT_FINAL|SLAP_AT_HIDE,
+			offsetof(monitor_info_t, mi_ad_monitorOpCompleted) },
+		{ "( 1.3.6.1.4.1.4203.666.1.55.5 "
+			"NAME 'monitorOpInitiated' "
+			"DESC 'monitor initiated operations' "
+			"SUP monitorCounter "
+			"NO-USER-MODIFICATION "
+			"USAGE dSAOperation )", SLAP_AT_FINAL|SLAP_AT_HIDE,
+			offsetof(monitor_info_t, mi_ad_monitorOpInitiated) },
+		{ "( 1.3.6.1.4.1.4203.666.1.55.6 "
+			"NAME 'monitorConnectionNumber' "
+			"DESC 'monitor connection number' "
+			"SUP monitorCounter "
+			"NO-USER-MODIFICATION "
+			"USAGE dSAOperation )", SLAP_AT_FINAL|SLAP_AT_HIDE,
+			offsetof(monitor_info_t, mi_ad_monitorConnectionNumber) },
+		{ "( 1.3.6.1.4.1.4203.666.1.55.7 "
+			"NAME 'monitorConnectionAuthzDN' "
+			"DESC 'monitor connection authorization DN' "
+			/* "SUP distinguishedName " */
+			"EQUALITY distinguishedNameMatch "
+			"SYNTAX 1.3.6.1.4.1.1466.115.121.1.12 "
+			"NO-USER-MODIFICATION "
+			"USAGE dSAOperation )", SLAP_AT_FINAL|SLAP_AT_HIDE,
+			offsetof(monitor_info_t, mi_ad_monitorConnectionAuthzDN) },
+		{ "( 1.3.6.1.4.1.4203.666.1.55.8 "
+			"NAME 'monitorConnectionLocalAddress' "
+			"DESC 'monitor connection local address' "
+			"SUP monitoredInfo "
+			"NO-USER-MODIFICATION "
+			"USAGE dSAOperation )", SLAP_AT_FINAL|SLAP_AT_HIDE,
+			offsetof(monitor_info_t, mi_ad_monitorConnectionLocalAddress) },
+		{ "( 1.3.6.1.4.1.4203.666.1.55.9 "
+			"NAME 'monitorConnectionPeerAddress' "
+			"DESC 'monitor connection peer address' "
+			"SUP monitoredInfo "
+			"NO-USER-MODIFICATION "
+			"USAGE dSAOperation )", SLAP_AT_FINAL|SLAP_AT_HIDE,
+			offsetof(monitor_info_t, mi_ad_monitorConnectionPeerAddress) },
+		{ "( 1.3.6.1.4.1.4203.666.1.55.10 "
+			"NAME 'monitorTimestamp' "
+			"DESC 'monitor timestamp' "
+			"EQUALITY generalizedTimeMatch "
+			"ORDERING generalizedTimeOrderingMatch "
+			"SYNTAX 1.3.6.1.4.1.1466.115.121.1.24 "
+			"SINGLE-VALUE "
+			"NO-USER-MODIFICATION "
+			"USAGE dSAOperation )", SLAP_AT_FINAL|SLAP_AT_HIDE,
+			offsetof(monitor_info_t, mi_ad_monitorTimestamp) },
+		{ "( 1.3.6.1.4.1.4203.666.1.55.11 "
+			"NAME 'monitorOverlay' "
+			"DESC 'name of overlays defined for a given database' "
+			"SUP monitoredInfo "
+			"NO-USER-MODIFICATION "
+			"USAGE dSAOperation )", SLAP_AT_HIDE,
+			offsetof(monitor_info_t, mi_ad_monitorOverlay) },
+		{ "( 1.3.6.1.4.1.4203.666.1.55.12 "
+			"NAME 'readOnly' "
+			"DESC 'read/write status of a given database' "
+			"EQUALITY booleanMatch "
+			"SYNTAX 1.3.6.1.4.1.1466.115.121.1.7 "
+			"SINGLE-VALUE "
+			"USAGE dSAOperation )", SLAP_AT_HIDE,
+			offsetof(monitor_info_t, mi_ad_readOnly) },
+		{ "( 1.3.6.1.4.1.4203.666.1.55.13 "
+			"NAME 'restrictedOperation' "
+			"DESC 'name of restricted operation for a given database' "
+			"SUP managedInfo )", SLAP_AT_HIDE,
+			offsetof(monitor_info_t, mi_ad_restrictedOperation ) },
+		{ "( 1.3.6.1.4.1.4203.666.1.55.14 "
+			"NAME 'monitorConnectionProtocol' "
+			"DESC 'monitor connection protocol' "
+			"SUP monitoredInfo "
+			"NO-USER-MODIFICATION "
+			"USAGE dSAOperation )", SLAP_AT_FINAL|SLAP_AT_HIDE,
+			offsetof(monitor_info_t, mi_ad_monitorConnectionProtocol) },
+		{ "( 1.3.6.1.4.1.4203.666.1.55.15 "
+			"NAME 'monitorConnectionOpsReceived' "
+			"DESC 'monitor number of operations received by the connection' "
+			"SUP monitorCounter "
+			"NO-USER-MODIFICATION "
+			"USAGE dSAOperation )", SLAP_AT_FINAL|SLAP_AT_HIDE,
+			offsetof(monitor_info_t, mi_ad_monitorConnectionOpsReceived) },
+		{ "( 1.3.6.1.4.1.4203.666.1.55.16 "
+			"NAME 'monitorConnectionOpsExecuting' "
+			"DESC 'monitor number of operations in execution within the connection' "
+			"SUP monitorCounter "
+			"NO-USER-MODIFICATION "
+			"USAGE dSAOperation )", SLAP_AT_FINAL|SLAP_AT_HIDE,
+			offsetof(monitor_info_t, mi_ad_monitorConnectionOpsExecuting) },
+		{ "( 1.3.6.1.4.1.4203.666.1.55.17 "
+			"NAME 'monitorConnectionOpsPending' "
+			"DESC 'monitor number of pending operations within the connection' "
+			"SUP monitorCounter "
+			"NO-USER-MODIFICATION "
+			"USAGE dSAOperation )", SLAP_AT_FINAL|SLAP_AT_HIDE,
+			offsetof(monitor_info_t, mi_ad_monitorConnectionOpsPending) },
+		{ "( 1.3.6.1.4.1.4203.666.1.55.18 "
+			"NAME 'monitorConnectionOpsCompleted' "
+			"DESC 'monitor number of operations completed within the connection' "
+			"SUP monitorCounter "
+			"NO-USER-MODIFICATION "
+			"USAGE dSAOperation )", SLAP_AT_FINAL|SLAP_AT_HIDE,
+			offsetof(monitor_info_t, mi_ad_monitorConnectionOpsCompleted) },
+		{ "( 1.3.6.1.4.1.4203.666.1.55.19 "
+			"NAME 'monitorConnectionGet' "
+			"DESC 'number of times connection_get() was called so far' "
+			"SUP monitorCounter "
+			"NO-USER-MODIFICATION "
+			"USAGE dSAOperation )", SLAP_AT_FINAL|SLAP_AT_HIDE,
+			offsetof(monitor_info_t, mi_ad_monitorConnectionGet) },
+		{ "( 1.3.6.1.4.1.4203.666.1.55.20 "
+			"NAME 'monitorConnectionRead' "
+			"DESC 'number of times connection_read() was called so far' "
+			"SUP monitorCounter "
+			"NO-USER-MODIFICATION "
+			"USAGE dSAOperation )", SLAP_AT_FINAL|SLAP_AT_HIDE,
+			offsetof(monitor_info_t, mi_ad_monitorConnectionRead) },
+		{ "( 1.3.6.1.4.1.4203.666.1.55.21 "
+			"NAME 'monitorConnectionWrite' "
+			"DESC 'number of times connection_write() was called so far' "
+			"SUP monitorCounter "
+			"NO-USER-MODIFICATION "
+			"USAGE dSAOperation )", SLAP_AT_FINAL|SLAP_AT_HIDE,
+			offsetof(monitor_info_t, mi_ad_monitorConnectionWrite) },
+		{ "( 1.3.6.1.4.1.4203.666.1.55.22 "
+			"NAME 'monitorConnectionMask' "
+			"DESC 'monitor connection mask' "
+			"SUP monitoredInfo "
+			"NO-USER-MODIFICATION "
+			"USAGE dSAOperation )", SLAP_AT_FINAL|SLAP_AT_HIDE,
+			offsetof(monitor_info_t, mi_ad_monitorConnectionMask) },
+		{ "( 1.3.6.1.4.1.4203.666.1.55.23 "
+			"NAME 'monitorConnectionListener' "
+			"DESC 'monitor connection listener' "
+			"SUP monitoredInfo "
+			"NO-USER-MODIFICATION "
+			"USAGE dSAOperation )", SLAP_AT_FINAL|SLAP_AT_HIDE,
+			offsetof(monitor_info_t, mi_ad_monitorConnectionListener) },
+		{ "( 1.3.6.1.4.1.4203.666.1.55.24 "
+			"NAME 'monitorConnectionPeerDomain' "
+			"DESC 'monitor connection peer domain' "
+			"SUP monitoredInfo "
+			"NO-USER-MODIFICATION "
+			"USAGE dSAOperation )", SLAP_AT_FINAL|SLAP_AT_HIDE,
+			offsetof(monitor_info_t, mi_ad_monitorConnectionPeerDomain) },
+		{ "( 1.3.6.1.4.1.4203.666.1.55.25 "
+			"NAME 'monitorConnectionStartTime' "
+			"DESC 'monitor connection start time' "
+			"SUP monitorTimestamp "
+			"SINGLE-VALUE "
+			"NO-USER-MODIFICATION "
+			"USAGE dSAOperation )", SLAP_AT_FINAL|SLAP_AT_HIDE,
+			offsetof(monitor_info_t, mi_ad_monitorConnectionStartTime) },
+		{ "( 1.3.6.1.4.1.4203.666.1.55.26 "
+			"NAME 'monitorConnectionActivityTime' "
+			"DESC 'monitor connection activity time' "
+			"SUP monitorTimestamp "
+			"SINGLE-VALUE "
+			"NO-USER-MODIFICATION "
+			"USAGE dSAOperation )", SLAP_AT_FINAL|SLAP_AT_HIDE,
+			offsetof(monitor_info_t, mi_ad_monitorConnectionActivityTime) },
+		{ "( 1.3.6.1.4.1.4203.666.1.55.27 "
+			"NAME 'monitorIsShadow' "
+			"DESC 'TRUE if the database is shadow' "
+			"EQUALITY booleanMatch "
+			"SYNTAX 1.3.6.1.4.1.1466.115.121.1.7 "
+			"SINGLE-VALUE "
+			"USAGE dSAOperation )", SLAP_AT_HIDE,
+			offsetof(monitor_info_t, mi_ad_monitorIsShadow) },
+		{ "( 1.3.6.1.4.1.4203.666.1.55.28 "
+			"NAME 'monitorUpdateRef' "
+			"DESC 'update referral for shadow databases' "
+			"SUP monitoredInfo "
+			"SINGLE-VALUE "
+			"USAGE dSAOperation )", SLAP_AT_HIDE,
+			offsetof(monitor_info_t, mi_ad_monitorUpdateRef) },
+		{ "( 1.3.6.1.4.1.4203.666.1.55.29 "
+			"NAME 'monitorRuntimeConfig' "
+			"DESC 'TRUE if component allows runtime configuration' "
+			"EQUALITY booleanMatch "
+			"SYNTAX 1.3.6.1.4.1.1466.115.121.1.7 "
+			"SINGLE-VALUE "
+			"USAGE dSAOperation )", SLAP_AT_HIDE,
+			offsetof(monitor_info_t, mi_ad_monitorRuntimeConfig) },
+		{ "( 1.3.6.1.4.1.4203.666.1.55.30 "
+			"NAME 'monitorSuperiorDN' "
+			"DESC 'monitor superior DN' "
+			/* "SUP distinguishedName " */
+			"EQUALITY distinguishedNameMatch "
+			"SYNTAX 1.3.6.1.4.1.1466.115.121.1.12 "
+			"NO-USER-MODIFICATION "
+			"USAGE dSAOperation )", SLAP_AT_FINAL|SLAP_AT_HIDE,
+			offsetof(monitor_info_t, mi_ad_monitorSuperiorDN) },
+		{ "( 1.3.6.1.4.1.4203.666.1.55.31 "
+			"NAME 'monitorConnectionOpsAsync' "
+			"DESC 'monitor number of asynchronous operations in execution within the connection' "
+			"SUP monitorCounter "
+			"NO-USER-MODIFICATION "
+			"USAGE dSAOperation )", SLAP_AT_FINAL|SLAP_AT_HIDE,
+			offsetof(monitor_info_t, mi_ad_monitorConnectionOpsAsync) },
+		{ "( 1.3.6.1.4.1.4203.666.1.55.32 "
+			"NAME 'monitorLogLevel' "
+			"DESC 'current slapd log level' "
+			"EQUALITY caseIgnoreMatch "
+			"SUBSTR caseIgnoreSubstringsMatch "
+			"SYNTAX 1.3.6.1.4.1.1466.115.121.1.15 "
+			"USAGE dSAOperation )", SLAP_AT_FINAL|SLAP_AT_HIDE,
+			offsetof(monitor_info_t, mi_ad_monitorLogLevel) },
+		{ "( 1.3.6.1.4.1.4203.666.1.55.33 "
+			"NAME 'monitorDebugLevel' "
+			"DESC 'current slapd debug level' "
+			"EQUALITY caseIgnoreMatch "
+			"SUBSTR caseIgnoreSubstringsMatch "
+			"SYNTAX 1.3.6.1.4.1.1466.115.121.1.15 "
+			"USAGE dSAOperation )", SLAP_AT_FINAL|SLAP_AT_HIDE,
+			offsetof(monitor_info_t, mi_ad_monitorDebugLevel) },
+		{ NULL, 0, -1 }
+	};
+
+	static struct {
+		char			*name;
+		char			*oid;
+	}		s_oid[] = {
+		{ "olmAttributes",			"1.3.6.1.4.1.4203.666.1.55" },
+		{ "olmSubSystemAttributes",		"olmAttributes:0" },
+		{ "olmGenericAttributes",		"olmSubSystemAttributes:0" },
+		{ "olmDatabaseAttributes",		"olmSubSystemAttributes:1" },
+		{ "olmOverlayAttributes",		"olmSubSystemAttributes:2" },
+		{ "olmModuleAttributes",		"olmSubSystemAttributes:3" },
+
+		/* for example, back-mdb specific attrs
+		 * are in "olmDatabaseAttributes:12"
+		 *
+		 * NOTE: developers, please record here OID assignments
+		 * for other modules */
+
+		{ "olmObjectClasses",			"1.3.6.1.4.1.4203.666.3.16" },
+		{ "olmSubSystemObjectClasses",		"olmObjectClasses:0" },
+		{ "olmGenericObjectClasses",		"olmSubSystemObjectClasses:0" },
+		{ "olmDatabaseObjectClasses",		"olmSubSystemObjectClasses:1" },
+		{ "olmOverlayObjectClasses",		"olmSubSystemObjectClasses:2" },
+		{ "olmModuleObjectClasses",			"olmSubSystemObjectClasses:3" },
+
+		/* for example, back-mdb specific objectClasses
+		 * are in "olmDatabaseObjectClasses:12"
+		 *
+		 * NOTE: developers, please record here OID assignments
+		 * for other modules */
+
+		{ NULL }
+	};
+
+	int			i, rc;
+	monitor_info_t		*mi = &monitor_info;
+	ConfigArgs c;
+	char	*argv[ 3 ];
+
+	argv[ 0 ] = "monitor";
+	c.argv = argv;
+	c.argc = 3;
+	c.fname = argv[0];
+
+	for ( i = 0; s_oid[ i ].name; i++ ) {
+		argv[ 1 ] = s_oid[ i ].name;
+		argv[ 2 ] = s_oid[ i ].oid;
+
+		if ( parse_oidm( &c, 0, NULL ) != 0 ) {
+			Debug( LDAP_DEBUG_ANY,
+				"monitor_back_initialize: unable to add "
+				"objectIdentifier \"%s=%s\"\n",
+				s_oid[ i ].name, s_oid[ i ].oid );
+			return 1;
+		}
+	}
+
+	/* schema integration */
+	for ( i = 0; mat[ i ].schema; i++ ) {
+		int			code;
+		AttributeDescription **ad =
+			((AttributeDescription **)&(((char *)mi)[ mat[ i ].offset ]));
+
+		*ad = NULL;
+		code = register_at( mat[ i ].schema, ad, 0 );
+
+		if ( code ) {
+			Debug( LDAP_DEBUG_ANY,
+				"monitor_back_db_init: register_at failed\n" );
+			return -1;
+		}
+		(*ad)->ad_type->sat_flags |= mat[ i ].flags;
+	}
+
+	for ( i = 0; moc[ i ].schema; i++ ) {
+		int			code;
+		ObjectClass		**Oc =
+			((ObjectClass **)&(((char *)mi)[ moc[ i ].offset ]));
+
+		code = register_oc( moc[ i ].schema, Oc, 0 );
+		if ( code ) {
+			Debug( LDAP_DEBUG_ANY,
+				"monitor_back_db_init: register_oc failed\n" );
+			return -1;
+		}
+		(*Oc)->soc_flags |= moc[ i ].flags;
+	}
+
+	bi->bi_controls = controls;
+
+	bi->bi_init = 0;
+	bi->bi_open = 0;
+	bi->bi_config = monitor_back_config;
+	bi->bi_close = 0;
+	bi->bi_destroy = 0;
+
+	bi->bi_db_init = monitor_back_db_init;
+#if 0
+	bi->bi_db_config = monitor_back_db_config;
+#endif
+	bi->bi_db_open = monitor_back_db_open;
+	bi->bi_db_close = 0;
+	bi->bi_db_destroy = monitor_back_db_destroy;
+
+	bi->bi_op_bind = monitor_back_bind;
+	bi->bi_op_unbind = 0;
+	bi->bi_op_search = monitor_back_search;
+	bi->bi_op_compare = monitor_back_compare;
+	bi->bi_op_modify = monitor_back_modify;
+	bi->bi_op_modrdn = 0;
+	bi->bi_op_add = 0;
+	bi->bi_op_delete = 0;
+	bi->bi_op_abandon = 0;
+
+	bi->bi_extended = 0;
+
+	bi->bi_entry_release_rw = monitor_back_release;
+	bi->bi_chk_referrals = 0;
+	bi->bi_operational = monitor_back_operational;
+
+	/*
+	 * hooks for slap tools
+	 */
+	bi->bi_tool_entry_open = 0;
+	bi->bi_tool_entry_close = 0;
+	bi->bi_tool_entry_first = 0;
+	bi->bi_tool_entry_first_x = 0;
+	bi->bi_tool_entry_next = 0;
+	bi->bi_tool_entry_get = 0;
+	bi->bi_tool_entry_put = 0;
+	bi->bi_tool_entry_reindex = 0;
+	bi->bi_tool_sync = 0;
+	bi->bi_tool_dn2id_get = 0;
+	bi->bi_tool_entry_modify = 0;
+
+	bi->bi_connection_init = 0;
+	bi->bi_connection_destroy = 0;
+
+	bi->bi_extra = (void *)&monitor_extra;
+
+	/*
+	 * configuration objectClasses (fake)
+	 */
+	bi->bi_cf_ocs = monitorocs;
+
+	rc = config_register_schema( monitorcfg, monitorocs );
+	if ( rc ) {
+		return rc;
+	}
+
+	return 0;
+}
+
+int
+monitor_back_db_init(
+	BackendDB	*be,
+	ConfigReply	*c)
+{
+	int			rc;
+	struct berval		dn = BER_BVC( SLAPD_MONITOR_DN ),
+				pdn,
+				ndn;
+	BackendDB		*be2;
+
+	monitor_subsys_t	*ms;
+
+	/*
+	 * database monitor can be defined once only
+	 */
+	if ( be_monitor != NULL ) {
+		if (c) {
+			snprintf(c->msg, sizeof(c->msg),"only one monitor database allowed");
+		}
+		return( -1 );
+	}
+	be_monitor = be;
+
+	/*
+	 * register subsys
+	 */
+	for ( ms = known_monitor_subsys; ms->mss_name != NULL; ms++ ) {
+		if ( monitor_back_register_subsys( ms ) ) {
+			return -1;
+		}
+	}
+
+	/* indicate system schema supported */
+	SLAP_BFLAGS(be) |= SLAP_BFLAG_MONITOR;
+
+	rc = dnPrettyNormal( NULL, &dn, &pdn, &ndn, NULL );
+	if( rc != LDAP_SUCCESS ) {
+		Debug( LDAP_DEBUG_ANY,
+			"unable to normalize/pretty monitor DN \"%s\" (%d)\n",
+			dn.bv_val, rc );
+		return -1;
+	}
+
+	ber_bvarray_add( &be->be_suffix, &pdn );
+	ber_bvarray_add( &be->be_nsuffix, &ndn );
+
+	/* NOTE: only one monitor database is allowed,
+	 * so we use static storage */
+	ldap_pvt_thread_mutex_init( &monitor_info.mi_cache_lock );
+
+	be->be_private = &monitor_info;
+
+	be2 = select_backend( &ndn, 0 );
+	if ( be2 != be ) {
+		char	*type = be2->bd_info->bi_type;
+
+		if ( overlay_is_over( be2 ) ) {
+			slap_overinfo	*oi = (slap_overinfo *)be2->bd_info->bi_private;
+			type = oi->oi_orig->bi_type;
+		}
+
+		if (c) {
+			snprintf(c->msg, sizeof(c->msg),
+					"\"monitor\" database serving namingContext \"%s\" "
+					"is hidden by \"%s\" database serving namingContext \"%s\".\n",
+					pdn.bv_val, type, be2->be_nsuffix[ 0 ].bv_val );
+		}
+		return -1;
+	}
+
+	return 0;
+}
+
+static void
+monitor_back_destroy_limbo_entry(
+	entry_limbo_t	*el,
+	int		dispose )
+{
+	if ( el->el_e ) {
+		entry_free( el->el_e );
+	}
+	if ( el->el_a ) {
+		attrs_free( el->el_a );
+	}
+	if ( !BER_BVISNULL( &el->el_nbase ) ) {
+		ber_memfree( el->el_nbase.bv_val );
+	}
+	if ( !BER_BVISNULL( &el->el_filter ) ) {
+		ber_memfree( el->el_filter.bv_val );
+	}
+
+	/* NOTE: callbacks are not copied; so only free them
+	 * if disposing of */
+	if ( el->el_cb && dispose != 0 ) {
+		monitor_callback_t *next;
+
+		for ( ; el->el_cb; el->el_cb = next ) {
+			next = el->el_cb->mc_next;
+			if ( el->el_cb->mc_dispose ) {
+				el->el_cb->mc_dispose( &el->el_cb->mc_private );
+			}
+			ch_free( el->el_cb );
+		}
+	}
+
+	ch_free( el );
+}
+
+int
+monitor_back_db_open(
+	BackendDB	*be,
+	ConfigReply	*cr)
+{
+	monitor_info_t 		*mi = (monitor_info_t *)be->be_private;
+	struct monitor_subsys_t	**ms;
+	Entry 			*e, *root;
+	monitor_entry_t		*mp;
+	int			i;
+	struct berval		bv, rdn = BER_BVC(SLAPD_MONITOR_DN);
+	struct tm		tms;
+	static char		tmbuf[ LDAP_LUTIL_GENTIME_BUFSIZE ];
+	struct berval	desc[] = {
+		BER_BVC("This subtree contains monitoring/managing objects."),
+		BER_BVC("This object contains information about this server."),
+		BER_BVC("Most of the information is held in operational"
+		" attributes, which must be explicitly requested."),
+		BER_BVNULL };
+
+	int			retcode = 0;
+
+	assert( be_monitor != NULL );
+	if ( be != be_monitor ) {
+		be_monitor = be;
+	}
+
+	/*
+	 * Start
+	 */
+	ldap_pvt_gmtime( &starttime, &tms );
+	lutil_gentime( tmbuf, sizeof(tmbuf), &tms );
+
+	mi->mi_startTime.bv_val = tmbuf;
+	mi->mi_startTime.bv_len = strlen( tmbuf );
+
+	if ( BER_BVISEMPTY( &be->be_rootdn ) ) {
+		BER_BVSTR( &mi->mi_creatorsName, SLAPD_ANONYMOUS );
+		BER_BVSTR( &mi->mi_ncreatorsName, SLAPD_ANONYMOUS );
+	} else {
+		mi->mi_creatorsName = be->be_rootdn;
+		mi->mi_ncreatorsName = be->be_rootndn;
+	}
+
+	/*
+	 * creates the "cn=Monitor" entry 
+	 */
+	e = monitor_entry_stub( NULL, NULL, &rdn, mi->mi_oc_monitorServer,
+		NULL, NULL );
+
+	if ( e == NULL) {
+		Debug( LDAP_DEBUG_ANY,
+			"unable to create \"%s\" entry\n",
+			SLAPD_MONITOR_DN );
+		return( -1 );
+	}
+
+	attr_merge_normalize( e, slap_schema.si_ad_description, desc, NULL );
+
+	bv.bv_val = strchr( (char *) Versionstr, '$' );
+	if ( bv.bv_val != NULL ) {
+		char	*end;
+
+		bv.bv_val++;
+		for ( ; bv.bv_val[ 0 ] == ' '; bv.bv_val++ )
+			;
+
+		end = strchr( bv.bv_val, '$' );
+		if ( end != NULL ) {
+			end--;
+
+			for ( ; end > bv.bv_val && end[ 0 ] == ' '; end-- )
+				;
+
+			end++;
+
+			bv.bv_len = end - bv.bv_val;
+
+		} else {
+			bv.bv_len = strlen( bv.bv_val );
+		}
+
+		if ( attr_merge_normalize_one( e, mi->mi_ad_monitoredInfo,
+					&bv, NULL ) ) {
+			Debug( LDAP_DEBUG_ANY,
+				"unable to add monitoredInfo to \"%s\" entry\n",
+				SLAPD_MONITOR_DN );
+			return( -1 );
+		}
+	}
+
+	mp = monitor_entrypriv_create();
+	if ( mp == NULL ) {
+		return -1;
+	}
+	e->e_private = ( void * )mp;
+
+	if ( monitor_cache_add( mi, e, NULL ) ) {
+		Debug( LDAP_DEBUG_ANY,
+			"unable to add entry \"%s\" to cache\n",
+			SLAPD_MONITOR_DN );
+		return -1;
+	}
+	root = e;
+
+	/*	
+	 * Create all the subsystem specific entries
+	 */
+	for ( i = 0; monitor_subsys[ i ] != NULL; i++ ) {
+		int 		len = strlen( monitor_subsys[ i ]->mss_name );
+		struct berval	dn;
+		int		rc;
+
+		dn.bv_len = len + sizeof( "cn=" ) - 1;
+		dn.bv_val = ch_calloc( sizeof( char ), dn.bv_len + 1 );
+		strcpy( dn.bv_val, "cn=" );
+		strcat( dn.bv_val, monitor_subsys[ i ]->mss_name );
+		rc = dnPretty( NULL, &dn, &monitor_subsys[ i ]->mss_rdn, NULL );
+		free( dn.bv_val );
+		if ( rc != LDAP_SUCCESS ) {
+			Debug( LDAP_DEBUG_ANY,
+				"monitor RDN \"%s\" is invalid\n", 
+				dn.bv_val );
+			return( -1 );
+		}
+
+		e = monitor_entry_stub( &root->e_name, &root->e_nname,
+			&monitor_subsys[ i ]->mss_rdn, mi->mi_oc_monitorContainer,
+			NULL, NULL );
+
+		if ( e == NULL) {
+			Debug( LDAP_DEBUG_ANY,
+				"unable to create \"%s\" entry\n", 
+				monitor_subsys[ i ]->mss_dn.bv_val );
+			return( -1 );
+		}
+		monitor_subsys[i]->mss_dn = e->e_name;
+		monitor_subsys[i]->mss_ndn = e->e_nname;
+
+		if ( !BER_BVISNULL( &monitor_subsys[ i ]->mss_desc[ 0 ] ) ) {
+			attr_merge_normalize( e, slap_schema.si_ad_description,
+					monitor_subsys[ i ]->mss_desc, NULL );
+		}
+
+		mp = monitor_entrypriv_create();
+		if ( mp == NULL ) {
+			return -1;
+		}
+		e->e_private = ( void * )mp;
+		mp->mp_info = monitor_subsys[ i ];
+		mp->mp_flags = monitor_subsys[ i ]->mss_flags;
+
+		if ( monitor_cache_add( mi, e, root ) ) {
+			Debug( LDAP_DEBUG_ANY,
+				"unable to add entry \"%s\" to cache\n",
+				monitor_subsys[ i ]->mss_dn.bv_val );
+			return -1;
+		}
+	}
+
+	assert( be != NULL );
+
+	be->be_private = mi;
+	
+	/*
+	 * opens the monitor backend subsystems
+	 */
+	for ( ms = monitor_subsys; ms[ 0 ] != NULL; ms++ ) {
+		if ( ms[ 0 ]->mss_open && ms[ 0 ]->mss_open( be, ms[ 0 ] ) ) {
+			return( -1 );
+		}
+		ms[ 0 ]->mss_flags |= MONITOR_F_OPENED;
+	}
+
+	monitor_subsys_opened = 1;
+
+	if ( mi->mi_entry_limbo ) {
+		entry_limbo_t	*el = mi->mi_entry_limbo;
+
+		for ( ; el; ) {
+			entry_limbo_t	*tmp;
+			int		rc;
+
+			switch ( el->el_type ) {
+			case LIMBO_ENTRY:
+				rc = monitor_back_register_entry(
+						el->el_e,
+						el->el_cb,
+						el->el_mss,
+						el->el_flags );
+				break;
+
+			case LIMBO_ENTRY_PARENT:
+				rc = monitor_back_register_entry_parent(
+						el->el_e,
+						el->el_cb,
+						el->el_mss,
+						el->el_flags,
+						&el->el_nbase,
+						el->el_scope,
+						&el->el_filter );
+				break;
+				
+
+			case LIMBO_ATTRS:
+				rc = monitor_back_register_entry_attrs(
+						el->el_ndn,
+						el->el_a,
+						el->el_cb,
+						&el->el_nbase,
+						el->el_scope,
+						&el->el_filter );
+				break;
+
+			case LIMBO_CB:
+				rc = monitor_back_register_entry_callback(
+						el->el_ndn,
+						el->el_cb,
+						&el->el_nbase,
+						el->el_scope,
+						&el->el_filter );
+				break;
+
+			case LIMBO_BACKEND:
+				rc = monitor_back_register_backend( el->el_bi );
+				break;
+
+			case LIMBO_DATABASE:
+				rc = monitor_back_register_database( el->el_be, el->el_ndn );
+				break;
+
+			case LIMBO_OVERLAY_INFO:
+				rc = monitor_back_register_overlay_info( el->el_on );
+				break;
+
+			case LIMBO_OVERLAY:
+				rc = monitor_back_register_overlay( el->el_be, el->el_on, el->el_ndn );
+				break;
+
+			case LIMBO_SUBSYS:
+				rc = monitor_back_register_subsys( el->el_mss );
+				break;
+
+			default:
+				assert( 0 );
+			}
+
+			tmp = el;
+			el = el->el_next;
+			monitor_back_destroy_limbo_entry( tmp, rc );
+
+			if ( rc != 0 ) {
+				/* try all, but report error at end */
+				retcode = 1;
+			}
+		}
+
+		mi->mi_entry_limbo = NULL;
+	}
+
+	return retcode;
+}
+
+int
+monitor_back_config(
+	BackendInfo	*bi,
+	const char	*fname,
+	int		lineno,
+	int		argc,
+	char		**argv )
+{
+	/*
+	 * eventually, will hold backend specific configuration parameters
+	 */
+	return SLAP_CONF_UNKNOWN;
+}
+
+#if 0
+int
+monitor_back_db_config(
+	Backend     *be,
+	const char  *fname,
+	int         lineno,
+	int         argc,
+	char        **argv )
+{
+	monitor_info_t	*mi = ( monitor_info_t * )be->be_private;
+
+	/*
+	 * eventually, will hold database specific configuration parameters
+	 */
+	return SLAP_CONF_UNKNOWN;
+}
+#endif
+
+int
+monitor_back_db_destroy(
+	BackendDB	*be,
+	ConfigReply	*cr)
+{
+	monitor_info_t	*mi = ( monitor_info_t * )be->be_private;
+
+	if ( mi == NULL ) {
+		return -1;
+	}
+
+	/*
+	 * FIXME: destroys all the data
+	 */
+	/* NOTE: mi points to static storage; don't free it */
+	
+	(void)monitor_cache_destroy( mi );
+
+	if ( monitor_subsys ) {
+		int	i;
+
+		for ( i = 0; monitor_subsys[ i ] != NULL; i++ ) {
+			if ( !BER_BVISNULL( &monitor_subsys[ i ]->mss_rdn ) ) {
+				ch_free( monitor_subsys[ i ]->mss_rdn.bv_val );
+			}
+
+			if ( monitor_subsys[ i ]->mss_destroy ) {
+				monitor_subsys[ i ]->mss_destroy( be, monitor_subsys[ i ] );
+			}
+		}
+
+		ch_free( monitor_subsys );
+	}
+
+	if ( mi->mi_entry_limbo ) {
+		entry_limbo_t	*el = mi->mi_entry_limbo;
+
+		for ( ; el; ) {
+			entry_limbo_t *tmp = el;
+			el = el->el_next;
+			monitor_back_destroy_limbo_entry( tmp, 1 );
+		}
+	}
+	
+	ldap_pvt_thread_mutex_destroy( &monitor_info.mi_cache_lock );
+
+	be->be_private = NULL;
+
+	return 0;
+}
diff --git a/servers/slapd/back-monitor/listener.c b/servers/slapd/back-monitor/listener.c
new file mode 100644
index 0000000..18e5d01
--- /dev/null
+++ b/servers/slapd/back-monitor/listener.c
@@ -0,0 +1,131 @@
+/* listener.c - deals with listener subsystem */
+/* $OpenLDAP$ */
+/* This work is part of OpenLDAP Software <http://www.openldap.org/>.
+ *
+ * Copyright 2001-2022 The OpenLDAP Foundation.
+ * Portions Copyright 2001-2003 Pierangelo Masarati.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted only as authorized by the OpenLDAP
+ * Public License.
+ *
+ * A copy of this license is available in file LICENSE in the
+ * top-level directory of the distribution or, alternatively, at
+ * <http://www.OpenLDAP.org/license.html>.
+ */
+/* ACKNOWLEDGEMENTS:
+ * This work was initially developed by Pierangelo Masarati for inclusion
+ * in OpenLDAP Software.
+ */
+
+#include "portable.h"
+
+#include <stdio.h>
+#include <ac/string.h>
+
+#include "slap.h"
+#include "back-monitor.h"
+
+int
+monitor_subsys_listener_init(
+	BackendDB		*be,
+	monitor_subsys_t	*ms
+)
+{
+	monitor_info_t	*mi;
+	Entry		*e_listener;
+	int		i;
+	monitor_entry_t	*mp;
+	Listener	**l;
+
+	assert( be != NULL );
+
+	if ( ( l = slapd_get_listeners() ) == NULL ) {
+		if ( slapMode & SLAP_TOOL_MODE ) {
+			return 0;
+		}
+
+		Debug( LDAP_DEBUG_ANY,
+			"monitor_subsys_listener_init: "
+			"unable to get listeners\n" );
+		return( -1 );
+	}
+
+	mi = ( monitor_info_t * )be->be_private;
+
+	if ( monitor_cache_get( mi, &ms->mss_ndn, &e_listener ) ) {
+		Debug( LDAP_DEBUG_ANY,
+			"monitor_subsys_listener_init: "
+			"unable to get entry \"%s\"\n",
+			ms->mss_ndn.bv_val );
+		return( -1 );
+	}
+
+	for ( i = 0; l[ i ]; i++ ) {
+		char 		buf[ BACKMONITOR_BUFSIZE ];
+		Entry		*e;
+		struct berval bv;
+
+		bv.bv_len = snprintf( buf, sizeof( buf ),
+				"cn=Listener %d", i );
+		bv.bv_val = buf;
+		e = monitor_entry_stub( &ms->mss_dn, &ms->mss_ndn, &bv,
+			mi->mi_oc_monitoredObject, NULL, NULL );
+
+		if ( e == NULL ) {
+			Debug( LDAP_DEBUG_ANY,
+				"monitor_subsys_listener_init: "
+				"unable to create entry \"cn=Listener %d,%s\"\n",
+				i, ms->mss_ndn.bv_val );
+			return( -1 );
+		}
+
+		attr_merge_normalize_one( e, mi->mi_ad_monitorConnectionLocalAddress,
+				&l[ i ]->sl_name, NULL );
+
+		attr_merge_normalize_one( e, slap_schema.si_ad_labeledURI,
+				&l[ i ]->sl_url, NULL );
+
+#ifdef HAVE_TLS
+		if ( l[ i ]->sl_is_tls ) {
+			struct berval bv;
+
+			BER_BVSTR( &bv, "TLS" );
+			attr_merge_normalize_one( e, mi->mi_ad_monitoredInfo,
+					&bv, NULL );
+		}
+#endif /* HAVE_TLS */
+#ifdef LDAP_CONNECTIONLESS
+		if ( l[ i ]->sl_is_udp ) {
+			struct berval bv;
+
+			BER_BVSTR( &bv, "UDP" );
+			attr_merge_normalize_one( e, mi->mi_ad_monitoredInfo,
+					&bv, NULL );
+		}
+#endif /* HAVE_TLS */
+
+		mp = monitor_entrypriv_create();
+		if ( mp == NULL ) {
+			return -1;
+		}
+		e->e_private = ( void * )mp;
+		mp->mp_info = ms;
+		mp->mp_flags = ms->mss_flags
+			| MONITOR_F_SUB;
+
+		if ( monitor_cache_add( mi, e, e_listener ) ) {
+			Debug( LDAP_DEBUG_ANY,
+				"monitor_subsys_listener_init: "
+				"unable to add entry \"cn=Listener %d,%s\"\n",
+				i, ms->mss_ndn.bv_val );
+			return( -1 );
+		}
+	}
+	
+	monitor_cache_release( mi, e_listener );
+
+	return( 0 );
+}
+
diff --git a/servers/slapd/back-monitor/log.c b/servers/slapd/back-monitor/log.c
new file mode 100644
index 0000000..c3d7d53
--- /dev/null
+++ b/servers/slapd/back-monitor/log.c
@@ -0,0 +1,468 @@
+/* log.c - deal with log subsystem */
+/* $OpenLDAP$ */
+/* This work is part of OpenLDAP Software <http://www.openldap.org/>.
+ *
+ * Copyright 2001-2022 The OpenLDAP Foundation.
+ * Portions Copyright 2001-2003 Pierangelo Masarati.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted only as authorized by the OpenLDAP
+ * Public License.
+ *
+ * A copy of this license is available in file LICENSE in the
+ * top-level directory of the distribution or, alternatively, at
+ * <http://www.OpenLDAP.org/license.html>.
+ */
+/* ACKNOWLEDGEMENTS:
+ * This work was initially developed by Pierangelo Masarati for inclusion
+ * in OpenLDAP Software.
+ */
+
+#include "portable.h"
+
+#include <stdio.h>
+
+#include <ac/string.h>
+
+#include "slap.h"
+#include <lber_pvt.h>
+#include "lutil.h"
+#include "ldif.h"
+#include "back-monitor.h"
+
+static int 
+monitor_subsys_log_open( 
+	BackendDB		*be,
+	monitor_subsys_t	*ms );
+
+static int 
+monitor_subsys_log_modify( 
+	Operation		*op,
+	SlapReply		*rs,
+	Entry 			*e );
+
+/*
+ * log mutex
+ */
+ldap_pvt_thread_mutex_t		monitor_log_mutex;
+
+static int add_values( Operation *op, Entry *e, Modification *mod, int *newlevel );
+static int delete_values( Operation *op, Entry *e, Modification *mod, int *newlevel );
+static int replace_values( Operation *op, Entry *e, Modification *mod, int *newlevel );
+
+/*
+ * initializes log subentry
+ */
+int
+monitor_subsys_log_init(
+	BackendDB		*be,
+	monitor_subsys_t	*ms )
+{
+	ldap_pvt_thread_mutex_init( &monitor_log_mutex );
+	ms->mss_modify = monitor_subsys_log_modify;
+
+	return monitor_subsys_log_open( be, ms );
+}
+
+/*
+ * opens log subentry
+ */
+int
+monitor_subsys_log_open(
+	BackendDB		*be,
+	monitor_subsys_t	*ms )
+{
+	BerVarray	bva = NULL;
+	monitor_info_t	*mi = ( monitor_info_t * )be->be_private;
+	Entry *e = NULL;
+
+	if ( loglevel2bvarray( slap_debug_get(), &bva ) == 0 && bva != NULL ) {
+		if ( monitor_cache_get( mi, &ms->mss_ndn, &e ) ) {
+			Debug( LDAP_DEBUG_ANY,
+				"monitor_subsys_log_init: "
+				"unable to get entry \"%s\"\n",
+				ms->mss_ndn.bv_val );
+			ber_bvarray_free( bva );
+			return( -1 );
+		}
+
+		attr_merge_normalize( e, mi->mi_ad_monitorDebugLevel, bva, NULL );
+		ber_bvarray_free( bva );
+		bva = NULL;
+	}
+
+	if ( loglevel2bvarray( slap_syslog_get(), &bva ) == 0 && bva != NULL ) {
+		if ( !e && monitor_cache_get( mi, &ms->mss_ndn, &e ) ) {
+			Debug( LDAP_DEBUG_ANY,
+				"monitor_subsys_log_init: "
+				"unable to get entry \"%s\"\n",
+				ms->mss_ndn.bv_val );
+			ber_bvarray_free( bva );
+			return( -1 );
+		}
+
+		attr_merge_normalize( e, mi->mi_ad_monitorLogLevel, bva, NULL );
+		ber_bvarray_free( bva );
+	}
+
+	if ( e )
+		monitor_cache_release( mi, e );
+
+	return( 0 );
+}
+
+static int 
+monitor_subsys_log_modify( 
+	Operation		*op,
+	SlapReply		*rs,
+	Entry 			*e )
+{
+	monitor_info_t	*mi = ( monitor_info_t * )op->o_bd->be_private;
+	int		rc = LDAP_OTHER;
+	int		newdebug, newsyslog, *newptr;
+	Attribute	*save_attrs;
+	Modifications	*modlist = op->orm_modlist;
+	Modifications	*ml;
+
+	ldap_pvt_thread_mutex_lock( &monitor_log_mutex );
+
+	newdebug = slap_debug_get();
+	newsyslog = slap_syslog_get();
+
+	save_attrs = e->e_attrs;
+	e->e_attrs = attrs_dup( e->e_attrs );
+
+	for ( ml = modlist; ml != NULL; ml = ml->sml_next ) {
+		Modification	*mod = &ml->sml_mod;
+
+		/*
+		 * accept all operational attributes;
+		 * this includes modifiersName and modifyTimestamp
+		 * if lastmod is "on"
+		 */
+		if ( is_at_operational( mod->sm_desc->ad_type ) ) {
+			( void ) attr_delete( &e->e_attrs, mod->sm_desc );
+			rc = rs->sr_err = attr_merge( e, mod->sm_desc,
+					mod->sm_values, mod->sm_nvalues );
+			if ( rc != LDAP_SUCCESS ) {
+				break;
+			}
+			continue;
+
+		/*
+		 * only the monitorDebugLevel and monitorLogLevel attributes can be modified
+		 */
+		} else {
+			if ( mod->sm_desc == mi->mi_ad_monitorDebugLevel ) {
+				newptr = &newdebug;
+			} else if ( mod->sm_desc == mi->mi_ad_monitorLogLevel ) {
+				newptr = &newsyslog;
+			} else {
+				rc = rs->sr_err = LDAP_UNWILLING_TO_PERFORM;
+				break;
+			}
+		}
+
+		switch ( mod->sm_op ) {
+		case LDAP_MOD_ADD:
+			rc = add_values( op, e, mod, newptr );
+			break;
+			
+		case LDAP_MOD_DELETE:
+			rc = delete_values( op, e, mod, newptr );
+			break;
+
+		case LDAP_MOD_REPLACE:
+			rc = replace_values( op, e, mod, newptr );
+			break;
+
+		default:
+			rc = LDAP_OTHER;
+			break;
+		}
+
+		if ( rc != LDAP_SUCCESS ) {
+			rs->sr_err = rc;
+			break;
+		}
+	}
+
+	/* set the new debug level */
+	if ( rc == LDAP_SUCCESS ) {
+		const char	*text;
+		static char	textbuf[ BACKMONITOR_BUFSIZE ];
+
+		/* check for abandon */
+		if ( op->o_abandon ) {
+			rc = rs->sr_err = SLAPD_ABANDON;
+
+			goto cleanup;
+		}
+
+		/* check that the entry still obeys the schema */
+		rc = entry_schema_check( op, e, save_attrs, 0, 0, NULL,
+			&text, textbuf, sizeof( textbuf ) );
+		if ( rc != LDAP_SUCCESS ) {
+			rs->sr_err = rc;
+			goto cleanup;
+		}
+
+		/*
+		 * Do we need to protect this with a mutex?
+		 */
+		slap_syslog_set( newsyslog );
+		slap_debug_set( newdebug );
+	}
+
+cleanup:;
+	if ( rc == LDAP_SUCCESS ) {
+		attrs_free( save_attrs );
+
+	} else {
+		attrs_free( e->e_attrs );
+		e->e_attrs = save_attrs;
+	}
+	
+	ldap_pvt_thread_mutex_unlock( &monitor_log_mutex );
+
+	if ( rc == LDAP_SUCCESS ) {
+		rc = SLAP_CB_CONTINUE;
+	}
+
+	return rc;
+}
+
+static int
+check_constraints( Modification *mod, int *newlevel )
+{
+	int		i;
+
+	if ( mod->sm_nvalues != NULL ) {
+		ber_bvarray_free( mod->sm_nvalues );
+		mod->sm_nvalues = NULL;
+	}
+
+	for ( i = 0; !BER_BVISNULL( &mod->sm_values[ i ] ); i++ ) {
+		int		l;
+		struct berval	bv;
+
+		if ( str2loglevel( mod->sm_values[ i ].bv_val, &l ) ) {
+			return LDAP_CONSTRAINT_VIOLATION;
+		}
+
+		if ( loglevel2bv( l, &bv ) ) {
+			return LDAP_CONSTRAINT_VIOLATION;
+		}
+		
+		assert( bv.bv_len == mod->sm_values[ i ].bv_len );
+		
+		AC_MEMCPY( mod->sm_values[ i ].bv_val,
+				bv.bv_val, bv.bv_len );
+
+		*newlevel |= l;
+	}
+
+	return LDAP_SUCCESS;
+}	
+
+static int 
+add_values( Operation *op, Entry *e, Modification *mod, int *newlevel )
+{
+	Attribute	*a;
+	int		i, rc;
+	MatchingRule 	*mr = mod->sm_desc->ad_type->sat_equality;
+
+	assert( mod->sm_values != NULL );
+
+	rc = check_constraints( mod, newlevel );
+	if ( rc != LDAP_SUCCESS ) {
+		return rc;
+	}
+
+	a = attr_find( e->e_attrs, mod->sm_desc );
+
+	if ( a != NULL ) {
+		/* "managedInfo" SHOULD have appropriate rules ... */
+		if ( mr == NULL || !mr->smr_match ) {
+			return LDAP_INAPPROPRIATE_MATCHING;
+		}
+
+		for ( i = 0; !BER_BVISNULL( &mod->sm_values[ i ] ); i++ ) {
+			int rc;
+			int j;
+			const char *text = NULL;
+			struct berval asserted;
+
+			rc = asserted_value_validate_normalize(
+				mod->sm_desc, mr, SLAP_MR_EQUALITY,
+				&mod->sm_values[ i ], &asserted, &text,
+				op->o_tmpmemctx );
+
+			if ( rc != LDAP_SUCCESS ) {
+				return rc;
+			}
+
+			for ( j = 0; !BER_BVISNULL( &a->a_vals[ j ] ); j++ ) {
+				int match;
+				int rc = value_match( &match, mod->sm_desc, mr,
+					0, &a->a_nvals[ j ], &asserted, &text );
+
+				if ( rc == LDAP_SUCCESS && match == 0 ) {
+					free( asserted.bv_val );
+					return LDAP_TYPE_OR_VALUE_EXISTS;
+				}
+			}
+
+			free( asserted.bv_val );
+		}
+	}
+
+	/* no - add them */
+	rc = attr_merge_normalize( e, mod->sm_desc, mod->sm_values,
+		op->o_tmpmemctx );
+	if ( rc != LDAP_SUCCESS ) {
+		return rc;
+	}
+
+	return LDAP_SUCCESS;
+}
+
+static int
+delete_values( Operation *op, Entry *e, Modification *mod, int *newlevel )
+{
+	int             i, j, k, found, rc, nl = 0;
+	Attribute       *a;
+	MatchingRule 	*mr = mod->sm_desc->ad_type->sat_equality;
+
+	/* delete the entire attribute */
+	if ( mod->sm_values == NULL ) {
+		int rc = attr_delete( &e->e_attrs, mod->sm_desc );
+
+		if ( rc ) {
+			rc = LDAP_NO_SUCH_ATTRIBUTE;
+
+		} else {
+			*newlevel = 0;
+			rc = LDAP_SUCCESS;
+		}
+		return rc;
+	}
+
+	rc = check_constraints( mod, &nl );
+	if ( rc != LDAP_SUCCESS ) {
+		return rc;
+	}
+
+	*newlevel &= ~nl;
+
+	if ( mr == NULL || !mr->smr_match ) {
+		/* disallow specific attributes from being deleted if
+		 * no equality rule */
+		return LDAP_INAPPROPRIATE_MATCHING;
+	}
+
+	/* delete specific values - find the attribute first */
+	if ( (a = attr_find( e->e_attrs, mod->sm_desc )) == NULL ) {
+		return( LDAP_NO_SUCH_ATTRIBUTE );
+	}
+
+	/* find each value to delete */
+	for ( i = 0; !BER_BVISNULL( &mod->sm_values[ i ] ); i++ ) {
+		int rc;
+		const char *text = NULL;
+
+		struct berval asserted;
+
+		rc = asserted_value_validate_normalize(
+				mod->sm_desc, mr, SLAP_MR_EQUALITY,
+				&mod->sm_values[ i ], &asserted, &text,
+				op->o_tmpmemctx );
+
+		if( rc != LDAP_SUCCESS ) return rc;
+
+		found = 0;
+		for ( j = 0; !BER_BVISNULL( &a->a_vals[ j ] ); j++ ) {
+			int match;
+			int rc = value_match( &match, mod->sm_desc, mr,
+				0, &a->a_nvals[ j ], &asserted, &text );
+
+			if( rc == LDAP_SUCCESS && match != 0 ) {
+				continue;
+			}
+
+			/* found a matching value */
+			found = 1;
+
+			/* delete it */
+			if ( a->a_nvals != a->a_vals ) {
+				free( a->a_nvals[ j ].bv_val );
+				for ( k = j + 1; !BER_BVISNULL( &a->a_nvals[ k ] ); k++ ) {
+					a->a_nvals[ k - 1 ] = a->a_nvals[ k ];
+				}
+				BER_BVZERO( &a->a_nvals[ k - 1 ] );
+			}
+
+			free( a->a_vals[ j ].bv_val );
+			for ( k = j + 1; !BER_BVISNULL( &a->a_vals[ k ] ); k++ ) {
+				a->a_vals[ k - 1 ] = a->a_vals[ k ];
+			}
+			BER_BVZERO( &a->a_vals[ k - 1 ] );
+			a->a_numvals--;
+
+			break;
+		}
+
+		free( asserted.bv_val );
+
+		/* looked through them all w/o finding it */
+		if ( ! found ) {
+			return LDAP_NO_SUCH_ATTRIBUTE;
+		}
+	}
+
+	/* if no values remain, delete the entire attribute */
+	if ( BER_BVISNULL( &a->a_vals[ 0 ] ) ) {
+		assert( a->a_numvals == 0 );
+
+		/* should already be zero */
+		*newlevel = 0;
+		
+		if ( attr_delete( &e->e_attrs, mod->sm_desc ) ) {
+			return LDAP_NO_SUCH_ATTRIBUTE;
+		}
+	}
+
+	return LDAP_SUCCESS;
+}
+
+static int
+replace_values( Operation *op, Entry *e, Modification *mod, int *newlevel )
+{
+	int rc;
+
+	if ( mod->sm_values != NULL ) {
+		*newlevel = 0;
+		rc = check_constraints( mod, newlevel );
+		if ( rc != LDAP_SUCCESS ) {
+			return rc;
+		}
+	}
+
+	rc = attr_delete( &e->e_attrs, mod->sm_desc );
+
+	if ( rc != LDAP_SUCCESS && rc != LDAP_NO_SUCH_ATTRIBUTE ) {
+		return rc;
+	}
+
+	if ( mod->sm_values != NULL ) {
+		rc = attr_merge_normalize( e, mod->sm_desc, mod->sm_values,
+				op->o_tmpmemctx );
+		if ( rc != LDAP_SUCCESS ) {
+			return rc;
+		}
+	}
+
+	return LDAP_SUCCESS;
+}
+
diff --git a/servers/slapd/back-monitor/modify.c b/servers/slapd/back-monitor/modify.c
new file mode 100644
index 0000000..bc6543f
--- /dev/null
+++ b/servers/slapd/back-monitor/modify.c
@@ -0,0 +1,90 @@
+/* modify.c - monitor backend modify routine */
+/* $OpenLDAP$ */
+/* This work is part of OpenLDAP Software <http://www.openldap.org/>.
+ *
+ * Copyright 2001-2022 The OpenLDAP Foundation.
+ * Portions Copyright 2001-2003 Pierangelo Masarati.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted only as authorized by the OpenLDAP
+ * Public License.
+ *
+ * A copy of this license is available in file LICENSE in the
+ * top-level directory of the distribution or, alternatively, at
+ * <http://www.OpenLDAP.org/license.html>.
+ */
+/* ACKNOWLEDGEMENTS:
+ * This work was initially developed by Pierangelo Masarati for inclusion
+ * in OpenLDAP Software.
+ */
+
+#include "portable.h"
+
+#include <stdio.h>
+
+#include <ac/string.h>
+#include <ac/socket.h>
+
+#include "slap.h"
+#include "back-monitor.h"
+#include "proto-back-monitor.h"
+
+int
+monitor_back_modify( Operation *op, SlapReply *rs )
+{
+	int 		rc = 0;
+	monitor_info_t	*mi = ( monitor_info_t * )op->o_bd->be_private;
+	Entry		*matched;
+	Entry		*e;
+
+	Debug(LDAP_DEBUG_ARGS, "monitor_back_modify:\n" );
+
+	/* acquire and lock entry */
+	monitor_cache_dn2entry( op, rs, &op->o_req_ndn, &e, &matched );
+	if ( e == NULL ) {
+		rs->sr_err = LDAP_NO_SUCH_OBJECT;
+		if ( matched ) {
+			if ( !access_allowed_mask( op, matched,
+					slap_schema.si_ad_entry,
+					NULL, ACL_DISCLOSE, NULL, NULL ) )
+			{
+				/* do nothing */ ;
+			} else {
+				rs->sr_matched = matched->e_dn;
+			}
+		}
+		send_ldap_result( op, rs );
+		if ( matched != NULL ) {
+			rs->sr_matched = NULL;
+			monitor_cache_release( mi, matched );
+		}
+		return rs->sr_err;
+	}
+
+	if ( !acl_check_modlist( op, e, op->orm_modlist )) {
+		rc = LDAP_INSUFFICIENT_ACCESS;
+
+	} else {
+		assert( !SLAP_SHADOW( op->o_bd ) );
+		slap_mods_opattrs( op, &op->orm_modlist, 0 );
+
+		rc = monitor_entry_modify( op, rs, e );
+	}
+
+	if ( rc != LDAP_SUCCESS ) {
+		if ( !access_allowed_mask( op, e, slap_schema.si_ad_entry,
+				NULL, ACL_DISCLOSE, NULL, NULL ) )
+		{
+			rc = LDAP_NO_SUCH_OBJECT;
+		}
+	}
+
+	rs->sr_err = rc;
+	send_ldap_result( op, rs );
+
+	monitor_cache_release( mi, e );
+
+	return rs->sr_err;
+}
+
diff --git a/servers/slapd/back-monitor/operation.c b/servers/slapd/back-monitor/operation.c
new file mode 100644
index 0000000..921ee95
--- /dev/null
+++ b/servers/slapd/back-monitor/operation.c
@@ -0,0 +1,237 @@
+/* operation.c - deal with operation subsystem */
+/* $OpenLDAP$ */
+/* This work is part of OpenLDAP Software <http://www.openldap.org/>.
+ *
+ * Copyright 2001-2022 The OpenLDAP Foundation.
+ * Portions Copyright 2001-2003 Pierangelo Masarati.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted only as authorized by the OpenLDAP
+ * Public License.
+ *
+ * A copy of this license is available in file LICENSE in the
+ * top-level directory of the distribution or, alternatively, at
+ * <http://www.OpenLDAP.org/license.html>.
+ */
+/* ACKNOWLEDGEMENTS:
+ * This work was initially developed by Pierangelo Masarati for inclusion
+ * in OpenLDAP Software.
+ */
+
+#include "portable.h"
+
+#include <stdio.h>
+#include <ac/string.h>
+
+#include "slap.h"
+#include "back-monitor.h"
+#include "lber_pvt.h"
+
+struct monitor_ops_t {
+	struct berval	rdn;
+	struct berval	nrdn;
+} monitor_op[] = {
+	{ BER_BVC( "cn=Bind" ),		BER_BVNULL },
+	{ BER_BVC( "cn=Unbind" ),	BER_BVNULL },
+	{ BER_BVC( "cn=Search" ),	BER_BVNULL },
+	{ BER_BVC( "cn=Compare" ),	BER_BVNULL },
+	{ BER_BVC( "cn=Modify" ),	BER_BVNULL },
+	{ BER_BVC( "cn=Modrdn" ),	BER_BVNULL },
+	{ BER_BVC( "cn=Add" ),		BER_BVNULL },
+	{ BER_BVC( "cn=Delete" ),	BER_BVNULL },
+	{ BER_BVC( "cn=Abandon" ),	BER_BVNULL },
+	{ BER_BVC( "cn=Extended" ),	BER_BVNULL },
+	{ BER_BVNULL,			BER_BVNULL }
+};
+
+static int
+monitor_subsys_ops_destroy(
+	BackendDB		*be,
+	monitor_subsys_t	*ms );
+
+static int
+monitor_subsys_ops_update(
+	Operation		*op,
+	SlapReply		*rs,
+	Entry                   *e );
+
+int
+monitor_subsys_ops_init(
+	BackendDB		*be,
+	monitor_subsys_t	*ms )
+{
+	monitor_info_t	*mi;
+	
+	Entry		*e_op;
+	monitor_entry_t	*mp;
+	int 		i;
+	struct berval	bv_zero = BER_BVC( "0" );
+
+	assert( be != NULL );
+
+	ms->mss_destroy = monitor_subsys_ops_destroy;
+	ms->mss_update = monitor_subsys_ops_update;
+
+	mi = ( monitor_info_t * )be->be_private;
+
+	if ( monitor_cache_get( mi,
+			&ms->mss_ndn, &e_op ) )
+	{
+		Debug( LDAP_DEBUG_ANY,
+			"monitor_subsys_ops_init: "
+			"unable to get entry \"%s\"\n",
+			ms->mss_ndn.bv_val );
+		return( -1 );
+	}
+
+	attr_merge_one( e_op, mi->mi_ad_monitorOpInitiated, &bv_zero, NULL );
+	attr_merge_one( e_op, mi->mi_ad_monitorOpCompleted, &bv_zero, NULL );
+
+	for ( i = 0; i < SLAP_OP_LAST; i++ ) {
+		struct berval	rdn;
+		Entry		*e;
+		struct berval bv;
+
+		/*
+		 * Initiated ops
+		 */
+		e = monitor_entry_stub( &ms->mss_dn, &ms->mss_ndn, &monitor_op[i].rdn,
+			mi->mi_oc_monitorOperation, NULL, NULL );
+
+		if ( e == NULL ) {
+			Debug( LDAP_DEBUG_ANY,
+				"monitor_subsys_ops_init: "
+				"unable to create entry \"%s,%s\"\n",
+				monitor_op[ i ].rdn.bv_val,
+				ms->mss_ndn.bv_val );
+			return( -1 );
+		}
+
+		BER_BVSTR( &bv, "0" );
+		attr_merge_one( e, mi->mi_ad_monitorOpInitiated, &bv, NULL );
+		attr_merge_one( e, mi->mi_ad_monitorOpCompleted, &bv, NULL );
+
+		/* steal normalized RDN */
+		dnRdn( &e->e_nname, &rdn );
+		ber_dupbv( &monitor_op[ i ].nrdn, &rdn );
+	
+		mp = monitor_entrypriv_create();
+		if ( mp == NULL ) {
+			return -1;
+		}
+		e->e_private = ( void * )mp;
+		mp->mp_info = ms;
+		mp->mp_flags = ms->mss_flags \
+			| MONITOR_F_SUB | MONITOR_F_PERSISTENT;
+
+		if ( monitor_cache_add( mi, e, e_op ) ) {
+			Debug( LDAP_DEBUG_ANY,
+				"monitor_subsys_ops_init: "
+				"unable to add entry \"%s,%s\"\n",
+				monitor_op[ i ].rdn.bv_val,
+				ms->mss_ndn.bv_val );
+			return( -1 );
+		}
+	}
+
+	monitor_cache_release( mi, e_op );
+
+	return( 0 );
+}
+
+static int
+monitor_subsys_ops_destroy(
+	BackendDB		*be,
+	monitor_subsys_t	*ms )
+{
+	int		i;
+
+	for ( i = 0; i < SLAP_OP_LAST; i++ ) {
+		if ( !BER_BVISNULL( &monitor_op[ i ].nrdn ) ) {
+			ch_free( monitor_op[ i ].nrdn.bv_val );
+		}
+	}
+
+	return 0;
+}
+
+static int
+monitor_subsys_ops_update(
+	Operation		*op,
+	SlapReply		*rs,
+	Entry                   *e )
+{
+	monitor_info_t		*mi = ( monitor_info_t * )op->o_bd->be_private;
+
+	ldap_pvt_mp_t		nInitiated = LDAP_PVT_MP_INIT,
+				nCompleted = LDAP_PVT_MP_INIT;
+	struct berval		rdn;
+	int 			i;
+	Attribute		*a;
+	slap_counters_t *sc;
+	static struct berval	bv_ops = BER_BVC( "cn=operations" );
+
+	assert( mi != NULL );
+	assert( e != NULL );
+
+	dnRdn( &e->e_nname, &rdn );
+
+	if ( dn_match( &rdn, &bv_ops ) ) {
+		ldap_pvt_mp_init( nInitiated );
+		ldap_pvt_mp_init( nCompleted );
+
+		ldap_pvt_thread_mutex_lock( &slap_counters.sc_mutex );
+		ldap_pvt_mp_add( nInitiated, slap_counters.sc_ops_initiated );
+		ldap_pvt_mp_add( nCompleted, slap_counters.sc_ops_completed );
+		for ( sc = slap_counters.sc_next; sc; sc = sc->sc_next ) {
+			ldap_pvt_thread_mutex_lock( &sc->sc_mutex );
+			ldap_pvt_mp_add( nInitiated, sc->sc_ops_initiated );
+			ldap_pvt_mp_add( nCompleted, sc->sc_ops_completed );
+			ldap_pvt_thread_mutex_unlock( &sc->sc_mutex );
+		}
+		ldap_pvt_thread_mutex_unlock( &slap_counters.sc_mutex );
+		
+	} else {
+		for ( i = 0; i < SLAP_OP_LAST; i++ ) {
+			if ( dn_match( &rdn, &monitor_op[ i ].nrdn ) )
+			{
+				ldap_pvt_thread_mutex_lock( &slap_counters.sc_mutex );
+				ldap_pvt_mp_init_set( nInitiated, slap_counters.sc_ops_initiated_[ i ] );
+				ldap_pvt_mp_init_set( nCompleted, slap_counters.sc_ops_completed_[ i ] );
+				for ( sc = slap_counters.sc_next; sc; sc = sc->sc_next ) {
+					ldap_pvt_thread_mutex_lock( &sc->sc_mutex );
+					ldap_pvt_mp_add( nInitiated, sc->sc_ops_initiated_[ i ] );
+					ldap_pvt_mp_add( nCompleted, sc->sc_ops_completed_[ i ] );
+					ldap_pvt_thread_mutex_unlock( &sc->sc_mutex );
+				}
+				ldap_pvt_thread_mutex_unlock( &slap_counters.sc_mutex );
+				break;
+			}
+		}
+
+		if ( i == SLAP_OP_LAST ) {
+			/* not found ... */
+			return( 0 );
+		}
+	}
+
+	a = attr_find( e->e_attrs, mi->mi_ad_monitorOpInitiated );
+	assert ( a != NULL );
+
+	/* NOTE: no minus sign is allowed in the counters... */
+	UI2BV( &a->a_vals[ 0 ], nInitiated );
+	ldap_pvt_mp_clear( nInitiated );
+	
+	a = attr_find( e->e_attrs, mi->mi_ad_monitorOpCompleted );
+	assert ( a != NULL );
+
+	/* NOTE: no minus sign is allowed in the counters... */
+	UI2BV( &a->a_vals[ 0 ], nCompleted );
+	ldap_pvt_mp_clear( nCompleted );
+
+	/* FIXME: touch modifyTimestamp? */
+
+	return SLAP_CB_CONTINUE;
+}
+
diff --git a/servers/slapd/back-monitor/operational.c b/servers/slapd/back-monitor/operational.c
new file mode 100644
index 0000000..994b254
--- /dev/null
+++ b/servers/slapd/back-monitor/operational.c
@@ -0,0 +1,72 @@
+/* operational.c - monitor backend operational attributes function */
+/* $OpenLDAP$ */
+/* This work is part of OpenLDAP Software <http://www.openldap.org/>.
+ *
+ * Copyright 2001-2022 The OpenLDAP Foundation.
+ * Portions Copyright 2001-2003 Pierangelo Masarati.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted only as authorized by the OpenLDAP
+ * Public License.
+ *
+ * A copy of this license is available in file LICENSE in the
+ * top-level directory of the distribution or, alternatively, at
+ * <http://www.OpenLDAP.org/license.html>.
+ */
+/* ACKNOWLEDGEMENTS:
+ * This work was initially developed by Pierangelo Masarati for inclusion
+ * in OpenLDAP Software.
+ */
+
+#include "portable.h"
+
+#include <stdio.h>
+
+#include <ac/string.h>
+#include <ac/socket.h>
+
+#include "slap.h"
+#include "back-monitor.h"
+#include "proto-back-monitor.h"
+
+/*
+ * sets the supported operational attributes (if required)
+ */
+
+int
+monitor_back_operational(
+	Operation	*op,
+	SlapReply	*rs )
+{
+	Attribute	**ap;
+
+	assert( rs->sr_entry != NULL );
+
+	for ( ap = &rs->sr_operational_attrs; *ap; ap = &(*ap)->a_next ) {
+		if ( (*ap)->a_desc == slap_schema.si_ad_hasSubordinates ) {
+			break;
+		}
+	}
+
+	if ( *ap == NULL &&
+		attr_find( rs->sr_entry->e_attrs, slap_schema.si_ad_hasSubordinates ) == NULL &&
+		( SLAP_OPATTRS( rs->sr_attr_flags ) ||
+			ad_inlist( slap_schema.si_ad_hasSubordinates, rs->sr_attrs ) ) )
+	{
+		int			hs;
+		monitor_entry_t	*mp;
+
+		mp = ( monitor_entry_t * )rs->sr_entry->e_private;
+
+		assert( mp != NULL );
+
+		hs = MONITOR_HAS_CHILDREN( mp );
+		*ap = slap_operational_hasSubordinate( hs );
+		assert( *ap != NULL );
+		ap = &(*ap)->a_next;
+	}
+	
+	return LDAP_SUCCESS;
+}
+
diff --git a/servers/slapd/back-monitor/overlay.c b/servers/slapd/back-monitor/overlay.c
new file mode 100644
index 0000000..aac6767
--- /dev/null
+++ b/servers/slapd/back-monitor/overlay.c
@@ -0,0 +1,133 @@
+/* overlay.c - deals with overlay subsystem */
+/* This work is part of OpenLDAP Software <http://www.openldap.org/>.
+ *
+ * Copyright 2001-2022 The OpenLDAP Foundation.
+ * Portions Copyright 2001-2003 Pierangelo Masarati.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted only as authorized by the OpenLDAP
+ * Public License.
+ *
+ * A copy of this license is available in file LICENSE in the
+ * top-level directory of the distribution or, alternatively, at
+ * <http://www.OpenLDAP.org/license.html>.
+ */
+/* ACKNOWLEDGEMENTS:
+ * This work was initially developed by Pierangelo Masarati for inclusion
+ * in OpenLDAP Software.
+ */
+
+
+#include "portable.h"
+
+#include <stdio.h>
+#include <ac/string.h>
+
+#include "slap.h"
+#include "back-monitor.h"
+
+/*
+ * initializes overlay subentries
+ */
+int
+monitor_subsys_overlay_init(
+	BackendDB		*be,
+	monitor_subsys_t	*ms
+)
+{
+	monitor_info_t		*mi;
+	Entry			*e_overlay;
+	int			i;
+	monitor_entry_t		*mp;
+	slap_overinst		*on;
+	monitor_subsys_t	*ms_database;
+
+	mi = ( monitor_info_t * )be->be_private;
+
+	ms_database = monitor_back_get_subsys( SLAPD_MONITOR_DATABASE_NAME );
+	if ( ms_database == NULL ) {
+		Debug( LDAP_DEBUG_ANY,
+			"monitor_subsys_backend_init: "
+			"unable to get "
+			"\"" SLAPD_MONITOR_DATABASE_NAME "\" "
+			"subsystem\n" );
+		return -1;
+	}
+
+	if ( monitor_cache_get( mi, &ms->mss_ndn, &e_overlay ) ) {
+		Debug( LDAP_DEBUG_ANY,
+			"monitor_subsys_overlay_init: "
+			"unable to get entry \"%s\"\n",
+			ms->mss_ndn.bv_val );
+		return( -1 );
+	}
+
+	for ( on = overlay_next( NULL ), i = 0; on; on = overlay_next( on ), i++ ) {
+		char 		buf[ BACKMONITOR_BUFSIZE ];
+		struct berval 	bv;
+		int		j;
+		Entry		*e;
+		BackendDB	*be;
+
+		bv.bv_len = snprintf( buf, sizeof( buf ), "cn=Overlay %d", i );
+		bv.bv_val = buf;
+		e = monitor_entry_stub( &ms->mss_dn, &ms->mss_ndn, &bv,
+			mi->mi_oc_monitoredObject, NULL, NULL );
+		if ( e == NULL ) {
+			Debug( LDAP_DEBUG_ANY,
+				"monitor_subsys_overlay_init: "
+				"unable to create entry \"cn=Overlay %d,%s\"\n",
+				i, ms->mss_ndn.bv_val );
+			return( -1 );
+		}
+		ber_str2bv( on->on_bi.bi_type, 0, 0, &bv );
+		attr_merge_normalize_one( e, mi->mi_ad_monitoredInfo, &bv, NULL );
+		attr_merge_normalize_one( e, mi->mi_ad_monitorRuntimeConfig,
+			on->on_bi.bi_cf_ocs ? (struct berval *)&slap_true_bv :
+				(struct berval *)&slap_false_bv, NULL );
+		
+		attr_merge_normalize_one( e_overlay, mi->mi_ad_monitoredInfo,
+				&bv, NULL );
+
+		j = -1;
+		LDAP_STAILQ_FOREACH( be, &backendDB, be_next ) {
+			char		buf[ SLAP_LDAPDN_MAXLEN ];
+			struct berval	dn;
+
+			j++;
+			if ( !overlay_is_inst( be, on->on_bi.bi_type ) ) {
+				continue;
+			}
+
+			snprintf( buf, sizeof( buf ), "cn=Database %d,%s",
+					j, ms_database->mss_dn.bv_val );
+
+			ber_str2bv( buf, 0, 0, &dn );
+			attr_merge_normalize_one( e, slap_schema.si_ad_seeAlso,
+					&dn, NULL );
+		}
+		
+		mp = monitor_entrypriv_create();
+		if ( mp == NULL ) {
+			return -1;
+		}
+		e->e_private = ( void * )mp;
+		mp->mp_info = ms;
+		mp->mp_flags = ms->mss_flags
+			| MONITOR_F_SUB;
+
+		if ( monitor_cache_add( mi, e, e_overlay ) ) {
+			Debug( LDAP_DEBUG_ANY,
+				"monitor_subsys_overlay_init: "
+				"unable to add entry \"cn=Overlay %d,%s\"\n",
+				i, ms->mss_ndn.bv_val );
+			return( -1 );
+		}
+	}
+	
+	monitor_cache_release( mi, e_overlay );
+
+	return( 0 );
+}
+
diff --git a/servers/slapd/back-monitor/proto-back-monitor.h b/servers/slapd/back-monitor/proto-back-monitor.h
new file mode 100644
index 0000000..662ac6d
--- /dev/null
+++ b/servers/slapd/back-monitor/proto-back-monitor.h
@@ -0,0 +1,343 @@
+/* $OpenLDAP$ */
+/* This work is part of OpenLDAP Software <http://www.openldap.org/>.
+ *
+ * Copyright 2001-2022 The OpenLDAP Foundation.
+ * Portions Copyright 2001-2003 Pierangelo Masarati.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted only as authorized by the OpenLDAP
+ * Public License.
+ *
+ * A copy of this license is available in file LICENSE in the
+ * top-level directory of the distribution or, alternatively, at
+ * <http://www.OpenLDAP.org/license.html>.
+ */
+/* ACKNOWLEDGEMENTS:
+ * This work was initially developed by Pierangelo Masarati for inclusion
+ * in OpenLDAP Software.
+ */
+
+#ifndef _PROTO_BACK_MONITOR
+#define _PROTO_BACK_MONITOR
+
+#include <ldap_cdefs.h>
+
+LDAP_BEGIN_DECL
+
+/*
+ * backends
+ */
+int
+monitor_subsys_backend_init LDAP_P((
+	BackendDB		*be,
+	monitor_subsys_t	*ms ));
+
+/*
+ * cache
+ */
+extern int
+monitor_cache_cmp LDAP_P((
+	const void		*c1,
+	const void		*c2 ));
+extern int
+monitor_cache_dup LDAP_P((
+	void			*c1,
+	void			*c2 ));
+extern int
+monitor_cache_add LDAP_P((
+	monitor_info_t		*mi,
+	Entry			*e,
+	Entry			*parent ));
+extern int
+monitor_cache_get LDAP_P((
+	monitor_info_t		*mi,
+	struct berval		*ndn,
+	Entry			**ep ));
+extern int
+monitor_cache_remove LDAP_P((
+	monitor_info_t		*mi,
+	struct berval		*ndn,
+	Entry			**ep ));
+extern int
+monitor_cache_dn2entry LDAP_P((
+	Operation		*op,
+	SlapReply		*rs,
+	struct berval		*ndn,
+	Entry			**ep,
+	Entry			**matched ));
+extern int
+monitor_cache_lock LDAP_P((
+	Entry			*e ));
+extern int
+monitor_cache_release LDAP_P((
+	monitor_info_t		*mi,
+	Entry			*e ));
+
+extern int
+monitor_cache_destroy LDAP_P((
+	monitor_info_t		*mi ));
+
+extern int
+monitor_back_release(
+	Operation *op,
+	Entry *e,
+	int rw );
+
+/*
+ * connections
+ */
+extern int
+monitor_subsys_conn_init LDAP_P((
+	BackendDB		*be,
+	monitor_subsys_t	*ms ));
+
+/*
+ * databases 
+ */
+extern int
+monitor_subsys_database_init LDAP_P((
+	BackendDB		*be,
+	monitor_subsys_t	*ms ));
+
+/*
+ * entry
+ */
+extern int
+monitor_entry_update LDAP_P((
+	Operation		*op,
+	SlapReply		*rs,
+	Entry			*e ));
+extern int
+monitor_entry_create LDAP_P((
+	Operation		*op,
+	SlapReply		*rs,
+	struct berval		*ndn,
+	Entry			*e_parent,
+	Entry			**ep ));
+extern int
+monitor_entry_modify LDAP_P((
+	Operation		*op,
+	SlapReply		*rs,
+	Entry			*e ));
+extern int
+monitor_entry_test_flags LDAP_P((
+	monitor_entry_t		*mp,
+	int			cond ));
+extern monitor_entry_t *
+monitor_back_entrypriv_create LDAP_P((
+	void ));
+extern Entry *
+monitor_back_entry_stub LDAP_P((
+	struct berval	*pdn,
+	struct berval	*pndn,
+	struct berval	*rdn,
+	ObjectClass		*oc,
+	struct berval	*create,
+	struct berval	*modify ));
+extern Entry *
+monitor_back_entry_get_unlocked LDAP_P((
+	struct berval	*ndn ));
+
+#define monitor_entrypriv_create monitor_back_entrypriv_create
+#define monitor_entry_stub monitor_back_entry_stub
+#define monitor_entry_get_unlocked monitor_back_entry_get_unlocked
+
+/*
+ * init
+ */
+extern int
+monitor_subsys_is_opened LDAP_P((
+	void ));
+extern int
+monitor_back_register_subsys LDAP_P((
+	monitor_subsys_t	*ms ));
+extern int
+monitor_back_register_subsys_late LDAP_P((
+	monitor_subsys_t	*ms ));
+extern int
+monitor_back_register_backend LDAP_P((
+	BackendInfo		*bi ));
+extern int
+monitor_back_register_database LDAP_P((
+	BackendDB		*be,
+	struct berval	*ndn ));
+extern int
+monitor_back_register_overlay_info LDAP_P((
+	slap_overinst		*on ));
+extern int
+monitor_back_register_overlay LDAP_P((
+	BackendDB		*be,
+	struct slap_overinst	*on,
+	struct berval		*ndn_out ));
+extern int
+monitor_back_register_backend_limbo LDAP_P((
+	BackendInfo		*bi ));
+extern int
+monitor_back_register_database_limbo LDAP_P((
+	BackendDB		*be,
+	struct berval		*ndn_out ));
+extern int
+monitor_back_register_overlay_info_limbo LDAP_P((
+	slap_overinst		*on ));
+extern int
+monitor_back_register_overlay_limbo LDAP_P((
+	BackendDB		*be,
+	struct slap_overinst	*on,
+	struct berval		*ndn_out ));
+extern monitor_subsys_t *
+monitor_back_get_subsys LDAP_P((
+	const char		*name ));
+extern monitor_subsys_t *
+monitor_back_get_subsys_by_dn LDAP_P((
+	struct berval		*ndn,
+	int			sub ));
+extern int
+monitor_back_is_configured LDAP_P(( void ));
+extern int
+monitor_back_register_entry LDAP_P((
+	Entry			*e,
+	monitor_callback_t	*cb,
+	monitor_subsys_t	*mss,
+	unsigned long		flags ));
+extern int
+monitor_back_register_entry_parent LDAP_P((
+	Entry			*e,
+	monitor_callback_t	*cb,
+	monitor_subsys_t	*mss,
+	unsigned long		flags,
+	struct berval		*base,
+	int			scope,
+	struct berval		*filter ));
+extern int
+monitor_search2ndn LDAP_P((
+	struct berval		*base,
+	int			scope,
+	struct berval		*filter,
+	struct berval		*ndn ));
+extern int
+monitor_back_register_entry_attrs LDAP_P((
+	struct berval		*ndn,
+	Attribute		*a,
+	monitor_callback_t	*cb,
+	struct berval		*base,
+	int			scope,
+	struct berval		*filter ));
+extern int
+monitor_back_register_entry_callback LDAP_P((
+	struct berval		*ndn,
+	monitor_callback_t	*cb,
+	struct berval		*base,
+	int			scope,
+	struct berval		*filter ));
+extern int
+monitor_back_unregister_entry LDAP_P((
+	struct berval		*ndn ));
+extern int
+monitor_back_unregister_entry_parent LDAP_P((
+	struct berval		*nrdn,
+	monitor_callback_t	*target_cb,
+	struct berval		*base,
+	int			scope,
+	struct berval		*filter ));
+extern int
+monitor_back_unregister_entry_attrs LDAP_P((
+	struct berval		*ndn,
+	Attribute		*a,
+	monitor_callback_t	*cb,
+	struct berval		*base,
+	int			scope,
+	struct berval		*filter ));
+extern int
+monitor_back_unregister_entry_callback LDAP_P((
+	struct berval		*ndn,
+	monitor_callback_t	*cb,
+	struct berval		*base,
+	int			scope,
+	struct berval		*filter ));
+
+/*
+ * listener
+ */
+extern int
+monitor_subsys_listener_init LDAP_P((
+	BackendDB		*be,
+	monitor_subsys_t	*ms ));
+
+/*
+ * log
+ */
+extern int
+monitor_subsys_log_init LDAP_P((
+	BackendDB		*be,
+	monitor_subsys_t	*ms ));
+
+/*
+ * operations
+ */
+extern int
+monitor_subsys_ops_init LDAP_P((
+	BackendDB		*be,
+	monitor_subsys_t	*ms ));
+
+/*
+ * overlay
+ */
+extern int
+monitor_subsys_overlay_init LDAP_P((
+	BackendDB		*be,
+	monitor_subsys_t	*ms ));
+
+/*
+ * sent
+ */
+extern int
+monitor_subsys_sent_init LDAP_P((
+	BackendDB		*be,
+	monitor_subsys_t	*ms ));
+
+/*
+ * threads
+ */
+extern int
+monitor_subsys_thread_init LDAP_P((
+	BackendDB		*be,
+	monitor_subsys_t	*ms ));
+
+/*
+ * time
+ */
+extern int monitor_subsys_time_init LDAP_P((
+	BackendDB		*be,
+	monitor_subsys_t	*ms ));
+
+/*
+ * waiters
+ */
+extern int
+monitor_subsys_rww_init LDAP_P((
+	BackendDB		*be,
+	monitor_subsys_t	*ms ));
+
+/*
+ * former external.h
+ */
+
+extern BI_init			monitor_back_initialize;
+
+extern BI_db_init		monitor_back_db_init;
+extern BI_db_open		monitor_back_db_open;
+extern BI_config		monitor_back_config;
+extern BI_db_destroy		monitor_back_db_destroy;
+extern BI_db_config		monitor_back_db_config;
+
+extern BI_op_search		monitor_back_search;
+extern BI_op_compare		monitor_back_compare;
+extern BI_op_modify		monitor_back_modify;
+extern BI_op_bind		monitor_back_bind;
+extern BI_operational		monitor_back_operational;
+
+LDAP_END_DECL
+
+#endif /* _PROTO_BACK_MONITOR */
+
diff --git a/servers/slapd/back-monitor/rww.c b/servers/slapd/back-monitor/rww.c
new file mode 100644
index 0000000..db1b318
--- /dev/null
+++ b/servers/slapd/back-monitor/rww.c
@@ -0,0 +1,225 @@
+/* readw.c - deal with read waiters subsystem */
+/* $OpenLDAP$ */
+/* This work is part of OpenLDAP Software <http://www.openldap.org/>.
+ *
+ * Copyright 2001-2022 The OpenLDAP Foundation.
+ * Portions Copyright 2001-2003 Pierangelo Masarati.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted only as authorized by the OpenLDAP
+ * Public License.
+ *
+ * A copy of this license is available in file LICENSE in the
+ * top-level directory of the distribution or, alternatively, at
+ * <http://www.OpenLDAP.org/license.html>.
+ */
+/* ACKNOWLEDGEMENTS:
+ * This work was initially developed by Pierangelo Masarati for inclusion
+ * in OpenLDAP Software.
+ */
+
+#include "portable.h"
+
+#include <stdio.h>
+#include <ac/string.h>
+
+#include "slap.h"
+#include "lutil.h"
+#include "back-monitor.h"
+
+static int
+monitor_subsys_rww_destroy(
+	BackendDB		*be,
+	monitor_subsys_t	*ms );
+
+static int
+monitor_subsys_rww_update(
+	Operation		*op,
+	SlapReply		*rs,
+	Entry                   *e );
+
+enum {
+	MONITOR_RWW_READ = 0,
+	MONITOR_RWW_WRITE,
+
+	MONITOR_RWW_LAST
+};
+
+static struct monitor_rww_t {
+	struct berval	rdn;
+	struct berval	nrdn;
+} monitor_rww[] = {
+	{ BER_BVC("cn=Read"),		BER_BVNULL },
+	{ BER_BVC("cn=Write"),		BER_BVNULL },
+	{ BER_BVNULL,			BER_BVNULL }
+};
+
+int
+monitor_subsys_rww_init(
+	BackendDB		*be,
+	monitor_subsys_t	*ms )
+{
+	monitor_info_t	*mi;
+	
+	Entry		*e_conn;
+	monitor_entry_t	*mp;
+	int			i;
+
+	assert( be != NULL );
+
+	ms->mss_destroy = monitor_subsys_rww_destroy;
+	ms->mss_update = monitor_subsys_rww_update;
+
+	mi = ( monitor_info_t * )be->be_private;
+
+	if ( monitor_cache_get( mi, &ms->mss_ndn, &e_conn ) ) {
+		Debug( LDAP_DEBUG_ANY,
+			"monitor_subsys_rww_init: "
+			"unable to get entry \"%s\"\n",
+			ms->mss_ndn.bv_val );
+		return( -1 );
+	}
+
+	for ( i = 0; i < MONITOR_RWW_LAST; i++ ) {
+		struct berval		nrdn, bv;
+		Entry			*e;
+		
+		e = monitor_entry_stub( &ms->mss_dn, &ms->mss_ndn, &monitor_rww[i].rdn,
+			mi->mi_oc_monitorCounterObject, NULL, NULL );
+		if ( e == NULL ) {
+			Debug( LDAP_DEBUG_ANY,
+				"monitor_subsys_rww_init: "
+				"unable to create entry \"cn=Read,%s\"\n",
+				ms->mss_ndn.bv_val );
+			return( -1 );
+		}
+
+		/* steal normalized RDN */
+		dnRdn( &e->e_nname, &nrdn );
+		ber_dupbv( &monitor_rww[ i ].nrdn, &nrdn );
+	
+		BER_BVSTR( &bv, "0" );
+		attr_merge_one( e, mi->mi_ad_monitorCounter, &bv, NULL );
+	
+		mp = monitor_entrypriv_create();
+		if ( mp == NULL ) {
+			return -1;
+		}
+		e->e_private = ( void * )mp;
+		mp->mp_info = ms;
+		mp->mp_flags = ms->mss_flags \
+			| MONITOR_F_SUB | MONITOR_F_PERSISTENT;
+
+		if ( monitor_cache_add( mi, e, e_conn ) ) {
+			Debug( LDAP_DEBUG_ANY,
+				"monitor_subsys_rww_init: "
+				"unable to add entry \"%s,%s\"\n",
+				monitor_rww[ i ].rdn.bv_val,
+				ms->mss_ndn.bv_val );
+			return( -1 );
+		}
+	}
+
+	monitor_cache_release( mi, e_conn );
+
+	return( 0 );
+}
+
+static int
+monitor_subsys_rww_destroy(
+	BackendDB		*be,
+	monitor_subsys_t	*ms )
+{
+	int		i;
+
+	for ( i = 0; i < MONITOR_RWW_LAST; i++ ) {
+		ber_memfree_x( monitor_rww[ i ].nrdn.bv_val, NULL );
+	}
+
+	return 0;
+}
+
+static int
+monitor_subsys_rww_update(
+	Operation		*op,
+	SlapReply		*rs,
+	Entry                   *e )
+{
+	monitor_info_t *mi = (monitor_info_t *)op->o_bd->be_private;
+	Connection	*c;
+	ber_socket_t	connindex;
+	long		nconns, nwritewaiters, nreadwaiters;
+
+	int		i;
+	struct berval	nrdn;
+
+	Attribute	*a;
+	char 		buf[LDAP_PVT_INTTYPE_CHARS(long)];
+	long		num = 0;
+	ber_len_t	len;
+
+	assert( mi != NULL );
+	assert( e != NULL );
+
+	dnRdn( &e->e_nname, &nrdn );
+
+	for ( i = 0; !BER_BVISNULL( &monitor_rww[ i ].nrdn ); i++ ) {
+		if ( dn_match( &nrdn, &monitor_rww[ i ].nrdn ) ) {
+			break;
+		}
+	}
+
+	if ( i == MONITOR_RWW_LAST ) {
+		return SLAP_CB_CONTINUE;
+	}
+
+	nconns = nwritewaiters = nreadwaiters = 0;
+	for ( c = connection_first( &connindex );
+			c != NULL;
+			c = connection_next( c, &connindex ), nconns++ )
+	{
+		if ( c->c_writewaiter ) {
+			nwritewaiters++;
+		}
+
+		/* FIXME: ?!? */
+		if ( c->c_currentber != NULL ) {
+			nreadwaiters++;
+		}
+	}
+	connection_done(c);
+
+	switch ( i ) {
+	case MONITOR_RWW_READ:
+		num = nreadwaiters;
+		break;
+
+	case MONITOR_RWW_WRITE:
+		num = nwritewaiters;
+		break;
+
+	default:
+		assert( 0 );
+	}
+
+	snprintf( buf, sizeof( buf ), "%ld", num );
+
+	a = attr_find( e->e_attrs, mi->mi_ad_monitorCounter );
+	assert( a != NULL );
+	len = strlen( buf );
+	if ( len > a->a_vals[ 0 ].bv_len ) {
+		a->a_vals[ 0 ].bv_val = ber_memrealloc( a->a_vals[ 0 ].bv_val, len + 1 );
+		if ( BER_BVISNULL( &a->a_vals[ 0 ] ) ) {
+			BER_BVZERO( &a->a_vals[ 0 ] );
+			return SLAP_CB_CONTINUE;
+		}
+	}
+	AC_MEMCPY( a->a_vals[ 0 ].bv_val, buf, len + 1 );
+	a->a_vals[ 0 ].bv_len = len;
+
+	/* FIXME: touch modifyTimestamp? */
+
+	return SLAP_CB_CONTINUE;
+}
+
diff --git a/servers/slapd/back-monitor/search.c b/servers/slapd/back-monitor/search.c
new file mode 100644
index 0000000..f58ff11
--- /dev/null
+++ b/servers/slapd/back-monitor/search.c
@@ -0,0 +1,275 @@
+/* search.c - monitor backend search function */
+/* $OpenLDAP$ */
+/* This work is part of OpenLDAP Software <http://www.openldap.org/>.
+ *
+ * Copyright 2001-2022 The OpenLDAP Foundation.
+ * Portions Copyright 2001-2003 Pierangelo Masarati.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted only as authorized by the OpenLDAP
+ * Public License.
+ *
+ * A copy of this license is available in file LICENSE in the
+ * top-level directory of the distribution or, alternatively, at
+ * <http://www.OpenLDAP.org/license.html>.
+ */
+/* ACKNOWLEDGEMENTS:
+ * This work was initially developed by Pierangelo Masarati for inclusion
+ * in OpenLDAP Software.
+ */
+
+#include "portable.h"
+
+#include <stdio.h>
+
+#include <ac/string.h>
+#include <ac/socket.h>
+
+#include "slap.h"
+#include "back-monitor.h"
+#include "proto-back-monitor.h"
+
+static void
+monitor_find_children(
+	Operation *op,
+	SlapReply *rs,
+	Entry *e_parent,
+	Entry **nonv,
+	Entry **vol
+)
+{
+	monitor_entry_t *mp;
+
+	mp = ( monitor_entry_t * )e_parent->e_private;
+	*nonv = mp->mp_children;
+
+	if ( MONITOR_HAS_VOLATILE_CH( mp ) ) {
+		monitor_entry_create( op, rs, NULL, e_parent, vol );
+	}
+}
+
+static int
+monitor_send_children(
+	Operation	*op,
+	SlapReply	*rs,
+	Entry		*e_nonvolatile,
+	Entry		*e_ch,
+	int		sub )
+{
+	monitor_info_t	*mi = ( monitor_info_t * )op->o_bd->be_private;
+	Entry 			*e,
+				*e_tmp;
+	monitor_entry_t *mp;
+	int			rc,
+				nonvolatile = 0;
+
+	e = e_nonvolatile;
+
+	/* no volatile entries? */
+	if ( e_ch == NULL ) {
+		/* no persistent entries? return */
+		if ( e == NULL ) {
+			return LDAP_SUCCESS;
+		}
+
+	/* volatile entries */
+	} else {
+		/* if no persistent, return only volatile */
+		if ( e == NULL ) {
+			e = e_ch;
+
+		/* else append persistent to volatile */
+		} else {
+			e_tmp = e_ch;
+			do {
+				mp = ( monitor_entry_t * )e_tmp->e_private;
+				e_tmp = mp->mp_next;
+	
+				if ( e_tmp == NULL ) {
+					mp->mp_next = e;
+					break;
+				}
+			} while ( e_tmp );
+			e = e_ch;
+		}
+	}
+
+	/* return entries */
+	for ( ; e != NULL; e = e_tmp ) {
+		Entry *sub_nv = NULL, *sub_ch = NULL, *locked = e;
+
+		monitor_cache_lock( e );
+		monitor_entry_update( op, rs, e );
+
+		if ( e == e_nonvolatile )
+			nonvolatile = 1;
+
+		mp = ( monitor_entry_t * )e->e_private;
+		e_tmp = mp->mp_next;
+
+		if ( op->o_abandon ) {
+			rc = SLAPD_ABANDON;
+			goto freeout;
+		}
+
+		if ( sub )
+			monitor_find_children( op, rs, e, &sub_nv, &sub_ch );
+
+		rc = test_filter( op, e, op->oq_search.rs_filter );
+		if ( rc == LDAP_COMPARE_TRUE ) {
+			rs->sr_entry = e;
+			rc = send_search_entry( op, rs );
+			if ( rc ) {
+				for ( e = sub_ch; e != NULL; e = sub_nv ) {
+					mp = ( monitor_entry_t * )e->e_private;
+					sub_nv = mp->mp_next;
+					monitor_cache_lock( e );
+					monitor_cache_release( mi, e );
+				}
+				goto freeout;
+			}
+		}
+		if ( sub_nv == NULL ) {
+			monitor_cache_release( mi, locked );
+			locked = NULL;
+		}
+
+		if ( sub ) {
+			rc = monitor_send_children( op, rs, sub_nv, sub_ch, sub );
+			if ( rc ) {
+freeout:
+				if ( locked ) {
+					monitor_cache_release( mi, locked );
+				}
+				if ( nonvolatile == 0 ) {
+					for ( ; e_tmp != NULL; ) {
+						mp = ( monitor_entry_t * )e_tmp->e_private;
+						e = e_tmp;
+						e_tmp = mp->mp_next;
+						monitor_cache_lock( e );
+						monitor_cache_release( mi, e );
+	
+						if ( e_tmp == e_nonvolatile ) {
+							break;
+						}
+					}
+				}
+
+				return( rc );
+			}
+		}
+		if ( locked ) {
+			monitor_cache_release( mi, locked );
+		}
+	}
+	
+	return LDAP_SUCCESS;
+}
+
+int
+monitor_back_search( Operation *op, SlapReply *rs )
+{
+	monitor_info_t	*mi = ( monitor_info_t * )op->o_bd->be_private;
+	int		rc = LDAP_SUCCESS;
+	Entry		*e = NULL, *matched = NULL;
+	Entry		*e_nv = NULL, *e_ch = NULL;
+	slap_mask_t	mask;
+
+	Debug( LDAP_DEBUG_TRACE, "=> monitor_back_search\n" );
+
+
+	/* get entry with reader lock */
+	monitor_cache_dn2entry( op, rs, &op->o_req_ndn, &e, &matched );
+	if ( e == NULL ) {
+		rs->sr_err = LDAP_NO_SUCH_OBJECT;
+		if ( matched ) {
+			if ( !access_allowed_mask( op, matched,
+					slap_schema.si_ad_entry,
+					NULL, ACL_DISCLOSE, NULL, NULL ) )
+			{
+				/* do nothing */ ;
+			} else {
+				rs->sr_matched = matched->e_dn;
+			}
+		}
+
+		send_ldap_result( op, rs );
+		if ( matched ) {
+			monitor_cache_release( mi, matched );
+			rs->sr_matched = NULL;
+		}
+
+		return rs->sr_err;
+	}
+
+	/* NOTE: __NEW__ "search" access is required
+	 * on searchBase object */
+	if ( !access_allowed_mask( op, e, slap_schema.si_ad_entry,
+				NULL, ACL_SEARCH, NULL, &mask ) )
+	{
+		monitor_cache_release( mi, e );
+
+		if ( !ACL_GRANT( mask, ACL_DISCLOSE ) ) {
+			rs->sr_err = LDAP_NO_SUCH_OBJECT;
+		} else {
+			rs->sr_err = LDAP_INSUFFICIENT_ACCESS;
+		}
+
+		send_ldap_result( op, rs );
+
+		return rs->sr_err;
+	}
+
+	rs->sr_attrs = op->oq_search.rs_attrs;
+	switch ( op->oq_search.rs_scope ) {
+	case LDAP_SCOPE_BASE:
+		monitor_entry_update( op, rs, e );
+		rc = test_filter( op, e, op->oq_search.rs_filter );
+ 		if ( rc == LDAP_COMPARE_TRUE ) {
+			rs->sr_entry = e;
+			rs->sr_flags = REP_ENTRY_MUSTRELEASE;
+			send_search_entry( op, rs );
+			rs->sr_entry = NULL;
+		} else {
+			monitor_cache_release( mi, e );
+		}
+		rc = LDAP_SUCCESS;
+		break;
+
+	case LDAP_SCOPE_ONELEVEL:
+	case LDAP_SCOPE_SUBORDINATE:
+		monitor_find_children( op, rs, e, &e_nv, &e_ch );
+		rc = monitor_send_children( op, rs, e_nv, e_ch,
+			op->oq_search.rs_scope == LDAP_SCOPE_SUBORDINATE );
+		monitor_cache_release( mi, e );
+		break;
+
+	case LDAP_SCOPE_SUBTREE:
+		monitor_entry_update( op, rs, e );
+		monitor_find_children( op, rs, e, &e_nv, &e_ch );
+		rc = test_filter( op, e, op->oq_search.rs_filter );
+		if ( rc == LDAP_COMPARE_TRUE ) {
+			rs->sr_entry = e;
+			send_search_entry( op, rs );
+			rs->sr_entry = NULL;
+		}
+
+		rc = monitor_send_children( op, rs, e_nv, e_ch, 1 );
+		monitor_cache_release( mi, e );
+		break;
+
+	default:
+		rc = LDAP_UNWILLING_TO_PERFORM;
+		monitor_cache_release( mi, e );
+	}
+
+	rs->sr_attrs = NULL;
+	rs->sr_err = rc;
+	if ( rs->sr_err != SLAPD_ABANDON ) {
+		send_ldap_result( op, rs );
+	}
+
+	return rs->sr_err;
+}
+
diff --git a/servers/slapd/back-monitor/sent.c b/servers/slapd/back-monitor/sent.c
new file mode 100644
index 0000000..24cc3b6
--- /dev/null
+++ b/servers/slapd/back-monitor/sent.c
@@ -0,0 +1,234 @@
+/* sent.c - deal with data sent subsystem */
+/* $OpenLDAP$ */
+/* This work is part of OpenLDAP Software <http://www.openldap.org/>.
+ *
+ * Copyright 2001-2022 The OpenLDAP Foundation.
+ * Portions Copyright 2001-2003 Pierangelo Masarati.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted only as authorized by the OpenLDAP
+ * Public License.
+ *
+ * A copy of this license is available in file LICENSE in the
+ * top-level directory of the distribution or, alternatively, at
+ * <http://www.OpenLDAP.org/license.html>.
+ */
+/* ACKNOWLEDGEMENTS:
+ * This work was initially developed by Pierangelo Masarati for inclusion
+ * in OpenLDAP Software.
+ */
+
+#include "portable.h"
+
+#include <stdio.h>
+#include <ac/string.h>
+
+#include "slap.h"
+#include "back-monitor.h"
+
+static int
+monitor_subsys_sent_destroy(
+	BackendDB		*be,
+	monitor_subsys_t	*ms );
+
+static int
+monitor_subsys_sent_update(
+	Operation		*op,
+	SlapReply		*rs,
+	Entry                   *e );
+
+enum {
+	MONITOR_SENT_BYTES = 0,
+	MONITOR_SENT_PDU,
+	MONITOR_SENT_ENTRIES,
+	MONITOR_SENT_REFERRALS,
+
+	MONITOR_SENT_LAST
+};
+
+struct monitor_sent_t {
+	struct berval	rdn;
+	struct berval	nrdn;
+} monitor_sent[] = {
+	{ BER_BVC("cn=Bytes"),		BER_BVNULL },
+	{ BER_BVC("cn=PDU"),		BER_BVNULL },
+	{ BER_BVC("cn=Entries"),	BER_BVNULL },
+	{ BER_BVC("cn=Referrals"),	BER_BVNULL },
+	{ BER_BVNULL,			BER_BVNULL }
+};
+
+int
+monitor_subsys_sent_init(
+	BackendDB		*be,
+	monitor_subsys_t	*ms )
+{
+	monitor_info_t	*mi;
+	
+	Entry		*e_sent;
+	monitor_entry_t	*mp;
+	int			i;
+
+	assert( be != NULL );
+
+	ms->mss_destroy = monitor_subsys_sent_destroy;
+	ms->mss_update = monitor_subsys_sent_update;
+
+	mi = ( monitor_info_t * )be->be_private;
+
+	if ( monitor_cache_get( mi, &ms->mss_ndn, &e_sent ) ) {
+		Debug( LDAP_DEBUG_ANY,
+			"monitor_subsys_sent_init: "
+			"unable to get entry \"%s\"\n",
+			ms->mss_ndn.bv_val );
+		return( -1 );
+	}
+
+	for ( i = 0; i < MONITOR_SENT_LAST; i++ ) {
+		struct berval		nrdn, bv;
+		Entry			*e;
+
+		e = monitor_entry_stub( &ms->mss_dn, &ms->mss_ndn,
+			&monitor_sent[i].rdn, mi->mi_oc_monitorCounterObject,
+			NULL, NULL );
+			
+		if ( e == NULL ) {
+			Debug( LDAP_DEBUG_ANY,
+				"monitor_subsys_sent_init: "
+				"unable to create entry \"%s,%s\"\n",
+				monitor_sent[ i ].rdn.bv_val,
+				ms->mss_ndn.bv_val );
+			return( -1 );
+		}
+
+		/* steal normalized RDN */
+		dnRdn( &e->e_nname, &nrdn );
+		ber_dupbv( &monitor_sent[ i ].nrdn, &nrdn );
+	
+		BER_BVSTR( &bv, "0" );
+		attr_merge_one( e, mi->mi_ad_monitorCounter, &bv, NULL );
+	
+		mp = monitor_entrypriv_create();
+		if ( mp == NULL ) {
+			return -1;
+		}
+		e->e_private = ( void * )mp;
+		mp->mp_info = ms;
+		mp->mp_flags = ms->mss_flags \
+			| MONITOR_F_SUB | MONITOR_F_PERSISTENT;
+
+		if ( monitor_cache_add( mi, e, e_sent ) ) {
+			Debug( LDAP_DEBUG_ANY,
+				"monitor_subsys_sent_init: "
+				"unable to add entry \"%s,%s\"\n",
+				monitor_sent[ i ].rdn.bv_val,
+				ms->mss_ndn.bv_val );
+			return( -1 );
+		}
+	}
+
+	monitor_cache_release( mi, e_sent );
+
+	return( 0 );
+}
+
+static int
+monitor_subsys_sent_destroy(
+	BackendDB		*be,
+	monitor_subsys_t	*ms )
+{
+	int		i;
+
+	for ( i = 0; i < MONITOR_SENT_LAST; i++ ) {
+		if ( !BER_BVISNULL( &monitor_sent[ i ].nrdn ) ) {
+			ch_free( monitor_sent[ i ].nrdn.bv_val );
+		}
+	}
+
+	return 0;
+}
+
+static int
+monitor_subsys_sent_update(
+	Operation		*op,
+	SlapReply		*rs,
+	Entry                   *e )
+{
+	monitor_info_t	*mi = ( monitor_info_t *)op->o_bd->be_private;
+	
+	struct berval		nrdn;
+	ldap_pvt_mp_t		n;
+	Attribute		*a;
+	slap_counters_t *sc;
+	int			i;
+
+	assert( mi != NULL );
+	assert( e != NULL );
+
+	dnRdn( &e->e_nname, &nrdn );
+
+	for ( i = 0; i < MONITOR_SENT_LAST; i++ ) {
+		if ( dn_match( &nrdn, &monitor_sent[ i ].nrdn ) ) {
+			break;
+		}
+	}
+
+	if ( i == MONITOR_SENT_LAST ) {
+		return SLAP_CB_CONTINUE;
+	}
+
+	ldap_pvt_thread_mutex_lock(&slap_counters.sc_mutex);
+	switch ( i ) {
+	case MONITOR_SENT_ENTRIES:
+		ldap_pvt_mp_init_set( n, slap_counters.sc_entries );
+		for ( sc = slap_counters.sc_next; sc; sc = sc->sc_next ) {
+			ldap_pvt_thread_mutex_lock( &sc->sc_mutex );
+			ldap_pvt_mp_add( n, sc->sc_entries );
+			ldap_pvt_thread_mutex_unlock( &sc->sc_mutex );
+		}
+		break;
+
+	case MONITOR_SENT_REFERRALS:
+		ldap_pvt_mp_init_set( n, slap_counters.sc_refs );
+		for ( sc = slap_counters.sc_next; sc; sc = sc->sc_next ) {
+			ldap_pvt_thread_mutex_lock( &sc->sc_mutex );
+			ldap_pvt_mp_add( n, sc->sc_refs );
+			ldap_pvt_thread_mutex_unlock( &sc->sc_mutex );
+		}
+		break;
+
+	case MONITOR_SENT_PDU:
+		ldap_pvt_mp_init_set( n, slap_counters.sc_pdu );
+		for ( sc = slap_counters.sc_next; sc; sc = sc->sc_next ) {
+			ldap_pvt_thread_mutex_lock( &sc->sc_mutex );
+			ldap_pvt_mp_add( n, sc->sc_pdu );
+			ldap_pvt_thread_mutex_unlock( &sc->sc_mutex );
+		}
+		break;
+
+	case MONITOR_SENT_BYTES:
+		ldap_pvt_mp_init_set( n, slap_counters.sc_bytes );
+		for ( sc = slap_counters.sc_next; sc; sc = sc->sc_next ) {
+			ldap_pvt_thread_mutex_lock( &sc->sc_mutex );
+			ldap_pvt_mp_add( n, sc->sc_bytes );
+			ldap_pvt_thread_mutex_unlock( &sc->sc_mutex );
+		}
+		break;
+
+	default:
+		assert(0);
+	}
+	ldap_pvt_thread_mutex_unlock(&slap_counters.sc_mutex);
+	
+	a = attr_find( e->e_attrs, mi->mi_ad_monitorCounter );
+	assert( a != NULL );
+
+	/* NOTE: no minus sign is allowed in the counters... */
+	UI2BV( &a->a_vals[ 0 ], n );
+	ldap_pvt_mp_clear( n );
+
+	/* FIXME: touch modifyTimestamp? */
+
+	return SLAP_CB_CONTINUE;
+}
+
diff --git a/servers/slapd/back-monitor/thread.c b/servers/slapd/back-monitor/thread.c
new file mode 100644
index 0000000..a29a875
--- /dev/null
+++ b/servers/slapd/back-monitor/thread.c
@@ -0,0 +1,344 @@
+/* thread.c - deal with thread subsystem */
+/* $OpenLDAP$ */
+/* This work is part of OpenLDAP Software <http://www.openldap.org/>.
+ *
+ * Copyright 2001-2022 The OpenLDAP Foundation.
+ * Portions Copyright 2001-2003 Pierangelo Masarati.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted only as authorized by the OpenLDAP
+ * Public License.
+ *
+ * A copy of this license is available in file LICENSE in the
+ * top-level directory of the distribution or, alternatively, at
+ * <http://www.OpenLDAP.org/license.html>.
+ */
+/* ACKNOWLEDGEMENTS:
+ * This work was initially developed by Pierangelo Masarati for inclusion
+ * in OpenLDAP Software.
+ */
+
+#include "portable.h"
+
+#include <stdio.h>
+#include <ac/string.h>
+
+#include "slap.h"
+#include "back-monitor.h"
+
+#include <ldap_rq.h>
+
+typedef enum {
+	MT_UNKNOWN,
+	MT_RUNQUEUE,
+	MT_TASKLIST,
+
+	MT_LAST
+} monitor_thread_t;
+
+static struct {
+	struct berval			rdn;
+	struct berval			desc;
+	struct berval			nrdn;
+	ldap_pvt_thread_pool_param_t	param;
+	monitor_thread_t		mt;
+}		mt[] = {
+	{ BER_BVC( "cn=Max" ),
+		BER_BVC("Maximum number of threads as configured"),
+		BER_BVNULL,	LDAP_PVT_THREAD_POOL_PARAM_MAX,		MT_UNKNOWN },
+	{ BER_BVC( "cn=Max Pending" ),
+		BER_BVC("Maximum number of pending threads"),
+		BER_BVNULL,	LDAP_PVT_THREAD_POOL_PARAM_MAX_PENDING,	MT_UNKNOWN },
+	{ BER_BVC( "cn=Open" ),		
+		BER_BVC("Number of open threads"),
+		BER_BVNULL,	LDAP_PVT_THREAD_POOL_PARAM_OPEN,	MT_UNKNOWN },
+	{ BER_BVC( "cn=Starting" ),	
+		BER_BVC("Number of threads being started"),
+		BER_BVNULL,	LDAP_PVT_THREAD_POOL_PARAM_STARTING,	MT_UNKNOWN },
+	{ BER_BVC( "cn=Active" ),	
+		BER_BVC("Number of active threads"),
+		BER_BVNULL,	LDAP_PVT_THREAD_POOL_PARAM_ACTIVE,	MT_UNKNOWN },
+	{ BER_BVC( "cn=Pending" ),	
+		BER_BVC("Number of pending threads"),
+		BER_BVNULL,	LDAP_PVT_THREAD_POOL_PARAM_PENDING,	MT_UNKNOWN },
+	{ BER_BVC( "cn=Backload" ),	
+		BER_BVC("Number of active plus pending threads"),
+		BER_BVNULL,	LDAP_PVT_THREAD_POOL_PARAM_BACKLOAD,	MT_UNKNOWN },
+#if 0	/* not meaningful right now */
+	{ BER_BVC( "cn=Active Max" ),
+		BER_BVNULL,
+		BER_BVNULL,	LDAP_PVT_THREAD_POOL_PARAM_ACTIVE_MAX,	MT_UNKNOWN },
+	{ BER_BVC( "cn=Pending Max" ),
+		BER_BVNULL,
+		BER_BVNULL,	LDAP_PVT_THREAD_POOL_PARAM_PENDING_MAX,	MT_UNKNOWN },
+	{ BER_BVC( "cn=Backload Max" ),
+		BER_BVNULL,
+		BER_BVNULL,	LDAP_PVT_THREAD_POOL_PARAM_BACKLOAD_MAX,MT_UNKNOWN },
+#endif
+	{ BER_BVC( "cn=State" ),
+		BER_BVC("Thread pool state"),
+		BER_BVNULL,	LDAP_PVT_THREAD_POOL_PARAM_STATE,	MT_UNKNOWN },
+
+	{ BER_BVC( "cn=Runqueue" ),
+		BER_BVC("Queue of running threads - besides those handling operations"),
+		BER_BVNULL,	LDAP_PVT_THREAD_POOL_PARAM_UNKNOWN,	MT_RUNQUEUE },
+	{ BER_BVC( "cn=Tasklist" ),
+		BER_BVC("List of running plus standby threads - besides those handling operations"),
+		BER_BVNULL,	LDAP_PVT_THREAD_POOL_PARAM_UNKNOWN,	MT_TASKLIST },
+
+	{ BER_BVNULL }
+};
+
+static int 
+monitor_subsys_thread_update( 
+	Operation		*op,
+	SlapReply		*rs,
+	Entry 			*e );
+
+/*
+ * initializes log subentry
+ */
+int
+monitor_subsys_thread_init(
+	BackendDB       	*be,
+	monitor_subsys_t	*ms )
+{
+	monitor_info_t	*mi;
+	monitor_entry_t	*mp;
+	Entry		*e, *e_thread;
+	int		i;
+
+	ms->mss_update = monitor_subsys_thread_update;
+
+	mi = ( monitor_info_t * )be->be_private;
+
+	if ( monitor_cache_get( mi, &ms->mss_ndn, &e_thread ) ) {
+		Debug( LDAP_DEBUG_ANY,
+			"monitor_subsys_thread_init: unable to get entry \"%s\"\n",
+			ms->mss_dn.bv_val );
+		return( -1 );
+	}
+
+	for ( i = 0; !BER_BVISNULL( &mt[ i ].rdn ); i++ ) {
+		static char	buf[ BACKMONITOR_BUFSIZE ];
+		int		count = -1;
+		char		*state = NULL;
+		struct berval	bv = BER_BVNULL;
+
+		/*
+		 * Max
+		 */
+		e = monitor_entry_stub( &ms->mss_dn, &ms->mss_ndn,
+			&mt[ i ].rdn,
+			mi->mi_oc_monitoredObject, NULL, NULL );
+		if ( e == NULL ) {
+			Debug( LDAP_DEBUG_ANY,
+				"monitor_subsys_thread_init: "
+				"unable to create entry \"%s,%s\"\n",
+				mt[ i ].rdn.bv_val,
+				ms->mss_ndn.bv_val );
+			return( -1 );
+		}
+
+		/* NOTE: reference to the normalized DN of the entry,
+		 * under the assumption it's not modified */
+		dnRdn( &e->e_nname, &mt[ i ].nrdn );
+
+		switch ( mt[ i ].param ) {
+		case LDAP_PVT_THREAD_POOL_PARAM_UNKNOWN:
+			break;
+
+		case LDAP_PVT_THREAD_POOL_PARAM_STATE:
+			if ( ldap_pvt_thread_pool_query( &connection_pool,
+				mt[ i ].param, (void *)&state ) == 0 )
+			{
+				ber_str2bv( state, 0, 0, &bv );
+
+			} else {
+				BER_BVSTR( &bv, "unknown" );
+			}
+			break;
+
+		default:
+			/* NOTE: in case of error, it'll be set to -1 */
+			(void)ldap_pvt_thread_pool_query( &connection_pool,
+				mt[ i ].param, (void *)&count );
+			bv.bv_val = buf;
+			bv.bv_len = snprintf( buf, sizeof( buf ), "%d", count );
+			break;
+		}
+
+		if ( !BER_BVISNULL( &bv ) ) {
+			attr_merge_normalize_one( e, mi->mi_ad_monitoredInfo, &bv, NULL );
+		}
+
+		if ( !BER_BVISNULL( &mt[ i ].desc ) ) {
+			attr_merge_normalize_one( e,
+				slap_schema.si_ad_description,
+				&mt[ i ].desc, NULL );
+		}
+	
+		mp = monitor_entrypriv_create();
+		if ( mp == NULL ) {
+			return -1;
+		}
+		e->e_private = ( void * )mp;
+		mp->mp_info = ms;
+		mp->mp_flags = ms->mss_flags \
+			| MONITOR_F_SUB | MONITOR_F_PERSISTENT;
+
+		if ( monitor_cache_add( mi, e, e_thread ) ) {
+			Debug( LDAP_DEBUG_ANY,
+				"monitor_subsys_thread_init: "
+				"unable to add entry \"%s,%s\"\n",
+				mt[ i ].rdn.bv_val,
+				ms->mss_dn.bv_val );
+			return( -1 );
+		}
+	}
+
+	monitor_cache_release( mi, e_thread );
+
+	return( 0 );
+}
+
+static int 
+monitor_subsys_thread_update( 
+	Operation		*op,
+	SlapReply		*rs,
+	Entry 			*e )
+{
+	monitor_info_t	*mi = ( monitor_info_t * )op->o_bd->be_private;
+	Attribute		*a;
+	BerVarray		vals = NULL;
+	char 			buf[ BACKMONITOR_BUFSIZE ];
+	struct berval		rdn, bv;
+	int			which, i;
+	struct re_s		*re;
+	int			count = -1;
+	char			*state = NULL;
+
+	assert( mi != NULL );
+
+	dnRdn( &e->e_nname, &rdn );
+
+	for ( i = 0; !BER_BVISNULL( &mt[ i ].nrdn ); i++ ) {
+		if ( dn_match( &mt[ i ].nrdn, &rdn ) ) {
+			break;
+		}
+	}
+
+	which = i;
+	if ( BER_BVISNULL( &mt[ which ].nrdn ) ) {
+		return SLAP_CB_CONTINUE;
+	}
+
+	a = attr_find( e->e_attrs, mi->mi_ad_monitoredInfo );
+
+	switch ( mt[ which ].param ) {
+	case LDAP_PVT_THREAD_POOL_PARAM_UNKNOWN:
+		switch ( mt[ which ].mt ) {
+		case MT_RUNQUEUE:
+			if ( a != NULL ) {
+				if ( a->a_nvals != a->a_vals ) {
+					ber_bvarray_free( a->a_nvals );
+				}
+				ber_bvarray_free( a->a_vals );
+				a->a_vals = NULL;
+				a->a_nvals = NULL;
+				a->a_numvals = 0;
+			}
+
+			i = 0;
+			bv.bv_val = buf;
+			ldap_pvt_thread_mutex_lock( &slapd_rq.rq_mutex );
+			LDAP_STAILQ_FOREACH( re, &slapd_rq.run_list, rnext ) {
+				bv.bv_len = snprintf( buf, sizeof( buf ), "{%d}%s(%s)",
+					i, re->tname, re->tspec );
+				if ( bv.bv_len < sizeof( buf ) ) {
+					value_add_one( &vals, &bv );
+				}
+				i++;
+			}
+			ldap_pvt_thread_mutex_unlock( &slapd_rq.rq_mutex );
+	
+			if ( vals ) {
+				attr_merge_normalize( e, mi->mi_ad_monitoredInfo, vals, NULL );
+				ber_bvarray_free( vals );
+
+			} else {
+				attr_delete( &e->e_attrs, mi->mi_ad_monitoredInfo );
+			}
+			break;
+
+		case MT_TASKLIST:
+			if ( a != NULL ) {
+				if ( a->a_nvals != a->a_vals ) {
+					ber_bvarray_free( a->a_nvals );
+				}
+				ber_bvarray_free( a->a_vals );
+				a->a_vals = NULL;
+				a->a_nvals = NULL;
+				a->a_numvals = 0;
+			}
+	
+			i = 0;
+			bv.bv_val = buf;
+			ldap_pvt_thread_mutex_lock( &slapd_rq.rq_mutex );
+			LDAP_STAILQ_FOREACH( re, &slapd_rq.task_list, tnext ) {
+				bv.bv_len = snprintf( buf, sizeof( buf ), "{%d}%s(%s)",
+					i, re->tname, re->tspec );
+				if ( bv.bv_len < sizeof( buf ) ) {
+					value_add_one( &vals, &bv );
+				}
+				i++;
+			}
+			ldap_pvt_thread_mutex_unlock( &slapd_rq.rq_mutex );
+	
+			if ( vals ) {
+				attr_merge_normalize( e, mi->mi_ad_monitoredInfo, vals, NULL );
+				ber_bvarray_free( vals );
+
+			} else {
+				attr_delete( &e->e_attrs, mi->mi_ad_monitoredInfo );
+			}
+			break;
+
+		default:
+			assert( 0 );
+		}
+		break;
+
+	case LDAP_PVT_THREAD_POOL_PARAM_STATE:
+		if ( a == NULL ) {
+			return rs->sr_err = LDAP_OTHER;
+		}
+		if ( ldap_pvt_thread_pool_query( &connection_pool,
+			mt[ i ].param, (void *)&state ) == 0 )
+		{
+			ber_str2bv( state, 0, 0, &bv );
+			ber_bvreplace( &a->a_vals[ 0 ], &bv );
+		}
+		break;
+
+	default:
+		if ( a == NULL ) {
+			return rs->sr_err = LDAP_OTHER;
+		}
+		if ( ldap_pvt_thread_pool_query( &connection_pool,
+			mt[ i ].param, (void *)&count ) == 0 )
+		{
+			bv.bv_val = buf;
+			bv.bv_len = snprintf( buf, sizeof( buf ), "%d", count );
+			if ( bv.bv_len < sizeof( buf ) ) {
+				ber_bvreplace( &a->a_vals[ 0 ], &bv );
+			}
+		}
+		break;
+	}
+
+	/* FIXME: touch modifyTimestamp? */
+
+	return SLAP_CB_CONTINUE;
+}
diff --git a/servers/slapd/back-monitor/time.c b/servers/slapd/back-monitor/time.c
new file mode 100644
index 0000000..53e0ac6
--- /dev/null
+++ b/servers/slapd/back-monitor/time.c
@@ -0,0 +1,234 @@
+/* time.c - deal with time subsystem */
+/* $OpenLDAP$ */
+/* This work is part of OpenLDAP Software <http://www.openldap.org/>.
+ *
+ * Copyright 2001-2022 The OpenLDAP Foundation.
+ * Portions Copyright 2001-2003 Pierangelo Masarati.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted only as authorized by the OpenLDAP
+ * Public License.
+ *
+ * A copy of this license is available in file LICENSE in the
+ * top-level directory of the distribution or, alternatively, at
+ * <http://www.OpenLDAP.org/license.html>.
+ */
+/* ACKNOWLEDGEMENTS:
+ * This work was initially developed by Pierangelo Masarati for inclusion
+ * in OpenLDAP Software.
+ */
+
+#include "portable.h"
+
+#include <stdio.h>
+#include <ac/string.h>
+#include <ac/time.h>
+
+
+#include "slap.h"
+#include <lutil.h>
+#include "proto-slap.h"
+#include "back-monitor.h"
+
+static int
+monitor_subsys_time_update(
+	Operation		*op,
+	SlapReply		*rs,
+	Entry                   *e );
+
+int
+monitor_subsys_time_init(
+	BackendDB		*be,
+	monitor_subsys_t	*ms )
+{
+	monitor_info_t	*mi;
+	
+	Entry		*e, *e_time;
+	monitor_entry_t	*mp;
+	struct berval	bv, value;
+
+	assert( be != NULL );
+
+	ms->mss_update = monitor_subsys_time_update;
+
+	mi = ( monitor_info_t * )be->be_private;
+
+	if ( monitor_cache_get( mi,
+			&ms->mss_ndn, &e_time ) ) {
+		Debug( LDAP_DEBUG_ANY,
+			"monitor_subsys_time_init: "
+			"unable to get entry \"%s\"\n",
+			ms->mss_ndn.bv_val );
+		return( -1 );
+	}
+
+	BER_BVSTR( &bv, "cn=Start" );
+	e = monitor_entry_stub( &ms->mss_dn, &ms->mss_ndn, &bv,
+		mi->mi_oc_monitoredObject, NULL, NULL );
+	if ( e == NULL ) {
+		Debug( LDAP_DEBUG_ANY,
+			"monitor_subsys_time_init: "
+			"unable to create entry \"%s,%s\"\n",
+			bv.bv_val, ms->mss_ndn.bv_val );
+		return( -1 );
+	}
+	attr_merge_normalize_one( e, mi->mi_ad_monitorTimestamp,
+		&mi->mi_startTime, NULL );
+	
+	mp = monitor_entrypriv_create();
+	if ( mp == NULL ) {
+		return -1;
+	}
+	e->e_private = ( void * )mp;
+	mp->mp_info = ms;
+	mp->mp_flags = ms->mss_flags \
+		| MONITOR_F_SUB | MONITOR_F_PERSISTENT;
+
+	if ( monitor_cache_add( mi, e, e_time ) ) {
+		Debug( LDAP_DEBUG_ANY,
+			"monitor_subsys_time_init: "
+			"unable to add entry \"%s,%s\"\n",
+			bv.bv_val, ms->mss_ndn.bv_val );
+		return( -1 );
+	}
+	
+	/*
+	 * Current
+	 */
+	BER_BVSTR( &bv, "cn=Current" );
+	e = monitor_entry_stub( &ms->mss_dn, &ms->mss_ndn, &bv,
+		mi->mi_oc_monitoredObject, NULL, NULL );
+	if ( e == NULL ) {
+		Debug( LDAP_DEBUG_ANY,
+			"monitor_subsys_time_init: "
+			"unable to create entry \"%s,%s\"\n",
+			bv.bv_val, ms->mss_ndn.bv_val );
+		return( -1 );
+	}
+	attr_merge_normalize_one( e, mi->mi_ad_monitorTimestamp,
+		&mi->mi_startTime, NULL );
+
+	mp = monitor_entrypriv_create();
+	if ( mp == NULL ) {
+		return -1;
+	}
+	e->e_private = ( void * )mp;
+	mp->mp_info = ms;
+	mp->mp_flags = ms->mss_flags \
+		| MONITOR_F_SUB | MONITOR_F_PERSISTENT;
+
+	if ( monitor_cache_add( mi, e, e_time ) ) {
+		Debug( LDAP_DEBUG_ANY,
+			"monitor_subsys_time_init: "
+			"unable to add entry \"%s,%s\"\n",
+			bv.bv_val, ms->mss_ndn.bv_val );
+		return( -1 );
+	}
+	
+	/*
+	 * Uptime
+	 */
+	BER_BVSTR( &bv, "cn=Uptime" );
+	e = monitor_entry_stub( &ms->mss_dn, &ms->mss_ndn, &bv,
+		mi->mi_oc_monitoredObject, NULL, NULL );
+	if ( e == NULL ) {
+		Debug( LDAP_DEBUG_ANY,
+			"monitor_subsys_time_init: "
+			"unable to create entry \"%s,%s\"\n",
+			bv.bv_val, ms->mss_ndn.bv_val );
+		return( -1 );
+	}
+	BER_BVSTR( &value, "0" );
+	attr_merge_normalize_one( e, mi->mi_ad_monitoredInfo,
+		&value, NULL );
+
+	mp = monitor_entrypriv_create();
+	if ( mp == NULL ) {
+		return -1;
+	}
+	e->e_private = ( void * )mp;
+	mp->mp_info = ms;
+	mp->mp_flags = ms->mss_flags \
+		| MONITOR_F_SUB | MONITOR_F_PERSISTENT;
+
+	if ( monitor_cache_add( mi, e, e_time ) ) {
+		Debug( LDAP_DEBUG_ANY,
+			"monitor_subsys_time_init: "
+			"unable to add entry \"%s,%s\"\n",
+			bv.bv_val, ms->mss_ndn.bv_val );
+		return( -1 );
+	}
+	
+	monitor_cache_release( mi, e_time );
+
+	return( 0 );
+}
+
+static int
+monitor_subsys_time_update(
+	Operation		*op,
+	SlapReply		*rs,
+	Entry                   *e )
+{
+	monitor_info_t		*mi = ( monitor_info_t * )op->o_bd->be_private;
+	static struct berval	bv_current = BER_BVC( "cn=current" ),
+				bv_uptime = BER_BVC( "cn=uptime" );
+	struct berval		rdn;
+
+	assert( mi != NULL );
+	assert( e != NULL );
+
+	dnRdn( &e->e_nname, &rdn );
+	
+	if ( dn_match( &rdn, &bv_current ) ) {
+		struct tm	tm;
+		char		tmbuf[ LDAP_LUTIL_GENTIME_BUFSIZE ];
+		Attribute	*a;
+		ber_len_t	len;
+		time_t		currtime;
+
+		currtime = slap_get_time();
+
+		ldap_pvt_gmtime( &currtime, &tm );
+		lutil_gentime( tmbuf, sizeof( tmbuf ), &tm );
+
+		len = strlen( tmbuf );
+
+		a = attr_find( e->e_attrs, mi->mi_ad_monitorTimestamp );
+		if ( a == NULL ) {
+			return rs->sr_err = LDAP_OTHER;
+		}
+
+		assert( len == a->a_vals[ 0 ].bv_len );
+		AC_MEMCPY( a->a_vals[ 0 ].bv_val, tmbuf, len );
+
+		/* FIXME: touch modifyTimestamp? */
+
+	} else if ( dn_match( &rdn, &bv_uptime ) ) {
+		Attribute	*a;
+		double		diff;
+		char		buf[ BACKMONITOR_BUFSIZE ];
+		struct berval	bv;
+
+		a = attr_find( e->e_attrs, mi->mi_ad_monitoredInfo );
+		if ( a == NULL ) {
+			return rs->sr_err = LDAP_OTHER;
+		}
+
+		diff = difftime( slap_get_time(), starttime );
+		bv.bv_len = snprintf( buf, sizeof( buf ), "%lu",
+			(unsigned long) diff );
+		bv.bv_val = buf;
+
+		ber_bvreplace( &a->a_vals[ 0 ], &bv );
+		if ( a->a_nvals != a->a_vals ) {
+			ber_bvreplace( &a->a_nvals[ 0 ], &bv );
+		}
+
+		/* FIXME: touch modifyTimestamp? */
+	}
+
+	return SLAP_CB_CONTINUE;
+}
+