Adding upstream version 2.4.47+dfsg.upstream/2.4.47+dfsgupstream

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

1 files changed, 1434 insertions, 0 deletions

diff --git a/servers/slapd/overlays/sssvlv.c b/servers/slapd/overlays/sssvlv.c
new file mode 100644
index 0000000..dff2929
--- /dev/null
+++ b/servers/slapd/overlays/sssvlv.c
@@ -0,0 +1,1434 @@
+/* sssvlv.c - server side sort / virtual list view */
+/* $OpenLDAP$ */
+/* This work is part of OpenLDAP Software <http://www.openldap.org/>.
+ *
+ * Copyright 2009-2018 The OpenLDAP Foundation.
+ * Portions copyright 2009 Symas Corporation.
+ * 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>.
+ */
+/* ACKNOWLEDGEMENTS:
+ * This work was initially developed by Howard Chu for inclusion in
+ * OpenLDAP Software. Support for multiple sorts per connection added
+ * by Raphael Ouazana.
+ */
+
+#include "portable.h"
+
+#ifdef SLAPD_OVER_SSSVLV
+
+#include <stdio.h>
+
+#include <ac/string.h>
+#include <ac/ctype.h>
+
+#include <avl.h>
+
+#include "slap.h"
+#include "lutil.h"
+#include "config.h"
+
+#include "../../../libraries/liblber/lber-int.h"	/* ber_rewind */
+
+/* RFC2891: Server Side Sorting
+ * RFC2696: Paged Results
+ */
+#ifndef LDAP_MATCHRULE_IDENTIFIER
+#define LDAP_MATCHRULE_IDENTIFIER      0x80L
+#define LDAP_REVERSEORDER_IDENTIFIER   0x81L
+#define LDAP_ATTRTYPES_IDENTIFIER      0x80L
+#endif
+
+/* draft-ietf-ldapext-ldapv3-vlv-09.txt: Virtual List Views
+ */
+#ifndef LDAP_VLVBYINDEX_IDENTIFIER
+#define LDAP_VLVBYINDEX_IDENTIFIER	   0xa0L
+#define LDAP_VLVBYVALUE_IDENTIFIER     0x81L
+#define LDAP_VLVCONTEXT_IDENTIFIER     0x04L
+
+#define LDAP_VLV_SSS_MISSING	0x4C
+#define LDAP_VLV_RANGE_ERROR	0x4D
+#endif
+
+#define SAFESTR(macro_str, macro_def) ((macro_str) ? (macro_str) : (macro_def))
+
+#define SSSVLV_DEFAULT_MAX_KEYS	5
+#define SSSVLV_DEFAULT_MAX_REQUEST_PER_CONN 5
+
+#define NO_PS_COOKIE (PagedResultsCookie) -1
+#define NO_VC_CONTEXT (unsigned long) -1
+
+typedef struct vlv_ctrl {
+	int vc_before;
+	int vc_after;
+	int	vc_offset;
+	int vc_count;
+	struct berval vc_value;
+	unsigned long vc_context;
+} vlv_ctrl;
+
+typedef struct sort_key
+{
+	AttributeDescription	*sk_ad;
+	MatchingRule			*sk_ordering;
+	int						sk_direction;	/* 1=normal, -1=reverse */
+} sort_key;
+
+typedef struct sort_ctrl {
+	int sc_nkeys;
+	sort_key sc_keys[1];
+} sort_ctrl;
+
+
+typedef struct sort_node
+{
+	int sn_conn;
+	int sn_session;
+	struct berval sn_dn;
+	struct berval *sn_vals;
+} sort_node;
+
+typedef struct sssvlv_info
+{
+	int svi_max;	/* max concurrent sorts */
+	int svi_num;	/* current # sorts */
+	int svi_max_keys;	/* max sort keys per request */
+	int svi_max_percon; /* max concurrent sorts per con */
+} sssvlv_info;
+
+typedef struct sort_op
+{
+	Avlnode	*so_tree;
+	sort_ctrl *so_ctrl;
+	sssvlv_info *so_info;
+	int so_paged;
+	int so_page_size;
+	int so_nentries;
+	int so_vlv;
+	int so_vlv_rc;
+	int so_vlv_target;
+	int so_session;
+	unsigned long so_vcontext;
+	int so_running;
+} sort_op;
+
+/* There is only one conn table for all overlay instances */
+/* Each conn can handle one session by context */
+static sort_op ***sort_conns;
+static ldap_pvt_thread_mutex_t sort_conns_mutex;
+static int ov_count;
+static const char *debug_header = "sssvlv";
+
+static int sss_cid;
+static int vlv_cid;
+
+/* RFC 2981 Section 2.2
+ * If a sort key is a multi-valued attribute, and an entry happens to
+ * have multiple values for that attribute and no other controls are
+ * present that affect the sorting order, then the server SHOULD use the
+ * least value (according to the ORDERING rule for that attribute).
+ */
+static struct berval* select_value(
+	Attribute		*attr,
+	sort_key			*key )
+{
+	struct berval* ber1, *ber2;
+	MatchingRule *mr = key->sk_ordering;
+	unsigned i;
+	int cmp;
+
+	ber1 = &(attr->a_nvals[0]);
+	ber2 = ber1+1;
+	for ( i = 1; i < attr->a_numvals; i++,ber2++ ) {
+		mr->smr_match( &cmp, 0, mr->smr_syntax, mr, ber1, ber2 );
+		if ( cmp > 0 ) {
+			ber1 = ber2;
+		}
+	}
+
+	Debug(LDAP_DEBUG_TRACE, "%s: value selected for compare: %s\n",
+		debug_header,
+		SAFESTR(ber1->bv_val, "<Empty>"),
+		0);
+
+	return ber1;
+}
+
+static int node_cmp( const void* val1, const void* val2 )
+{
+	sort_node *sn1 = (sort_node *)val1;
+	sort_node *sn2 = (sort_node *)val2;
+	sort_ctrl *sc;
+	MatchingRule *mr;
+	int i, cmp = 0;
+	assert( sort_conns[sn1->sn_conn]
+		&& sort_conns[sn1->sn_conn][sn1->sn_session]
+		&& sort_conns[sn1->sn_conn][sn1->sn_session]->so_ctrl );
+	sc = sort_conns[sn1->sn_conn][sn1->sn_session]->so_ctrl;
+
+	for ( i=0; cmp == 0 && i<sc->sc_nkeys; i++ ) {
+		if ( BER_BVISNULL( &sn1->sn_vals[i] )) {
+			if ( BER_BVISNULL( &sn2->sn_vals[i] ))
+				cmp = 0;
+			else
+				cmp = sc->sc_keys[i].sk_direction;
+		} else if ( BER_BVISNULL( &sn2->sn_vals[i] )) {
+			cmp = sc->sc_keys[i].sk_direction * -1;
+		} else {
+			mr = sc->sc_keys[i].sk_ordering;
+			mr->smr_match( &cmp, 0, mr->smr_syntax, mr,
+				&sn1->sn_vals[i], &sn2->sn_vals[i] );
+			if ( cmp )
+				cmp *= sc->sc_keys[i].sk_direction;
+		}
+	}
+	return cmp;
+}
+
+static int node_insert( const void *val1, const void *val2 )
+{
+	/* Never return equal so that new entries are always inserted */
+	return node_cmp( val1, val2 ) < 0 ? -1 : 1;
+}
+
+static int pack_vlv_response_control(
+	Operation		*op,
+	SlapReply		*rs,
+	sort_op			*so,
+	LDAPControl	**ctrlsp )
+{
+	LDAPControl			*ctrl;
+	BerElementBuffer	berbuf;
+	BerElement			*ber		= (BerElement *)&berbuf;
+	struct berval		cookie, bv;
+	int					rc;
+
+	ber_init2( ber, NULL, LBER_USE_DER );
+	ber_set_option( ber, LBER_OPT_BER_MEMCTX, &op->o_tmpmemctx );
+
+	rc = ber_printf( ber, "{iie", so->so_vlv_target, so->so_nentries,
+		so->so_vlv_rc );
+
+	if ( rc != -1 && so->so_vcontext ) {
+		cookie.bv_val = (char *)&so->so_vcontext;
+		cookie.bv_len = sizeof(so->so_vcontext);
+		rc = ber_printf( ber, "tO", LDAP_VLVCONTEXT_IDENTIFIER, &cookie );
+	}
+
+	if ( rc != -1 ) {
+		rc = ber_printf( ber, "}" );
+	}
+
+	if ( rc != -1 ) {
+		rc = ber_flatten2( ber, &bv, 0 );
+	}
+
+	if ( rc != -1 ) {
+		ctrl = (LDAPControl *)op->o_tmpalloc( sizeof(LDAPControl)+
+			bv.bv_len, op->o_tmpmemctx );
+		ctrl->ldctl_oid			= LDAP_CONTROL_VLVRESPONSE;
+		ctrl->ldctl_iscritical	= 0;
+		ctrl->ldctl_value.bv_val = (char *)(ctrl+1);
+		ctrl->ldctl_value.bv_len = bv.bv_len;
+		AC_MEMCPY( ctrl->ldctl_value.bv_val, bv.bv_val, bv.bv_len );
+		ctrlsp[0] = ctrl;
+	} else {
+		ctrlsp[0] = NULL;
+		rs->sr_err = LDAP_OTHER;
+	}
+
+	ber_free_buf( ber );
+
+	return rs->sr_err;
+}
+
+static int pack_pagedresult_response_control(
+	Operation		*op,
+	SlapReply		*rs,
+	sort_op			*so,
+	LDAPControl	**ctrlsp )
+{
+	LDAPControl			*ctrl;
+	BerElementBuffer	berbuf;
+	BerElement			*ber		= (BerElement *)&berbuf;
+	PagedResultsCookie	resp_cookie;
+	struct berval		cookie, bv;
+	int					rc;
+
+	ber_init2( ber, NULL, LBER_USE_DER );
+	ber_set_option( ber, LBER_OPT_BER_MEMCTX, &op->o_tmpmemctx );
+
+	if ( so->so_nentries > 0 ) {
+		resp_cookie		= ( PagedResultsCookie )so->so_tree;
+		cookie.bv_len	= sizeof( PagedResultsCookie );
+		cookie.bv_val	= (char *)&resp_cookie;
+	} else {
+		resp_cookie		= ( PagedResultsCookie )0;
+		BER_BVZERO( &cookie );
+	}
+
+	op->o_conn->c_pagedresults_state.ps_cookie = resp_cookie;
+	op->o_conn->c_pagedresults_state.ps_count
+		= ((PagedResultsState *)op->o_pagedresults_state)->ps_count
+		  + rs->sr_nentries;
+
+	rc = ber_printf( ber, "{iO}", so->so_nentries, &cookie );
+	if ( rc != -1 ) {
+		rc = ber_flatten2( ber, &bv, 0 );
+	}
+
+	if ( rc != -1 ) {
+		ctrl = (LDAPControl *)op->o_tmpalloc( sizeof(LDAPControl)+
+			bv.bv_len, op->o_tmpmemctx );
+		ctrl->ldctl_oid			= LDAP_CONTROL_PAGEDRESULTS;
+		ctrl->ldctl_iscritical	= 0;
+		ctrl->ldctl_value.bv_val = (char *)(ctrl+1);
+		ctrl->ldctl_value.bv_len = bv.bv_len;
+		AC_MEMCPY( ctrl->ldctl_value.bv_val, bv.bv_val, bv.bv_len );
+		ctrlsp[0] = ctrl;
+	} else {
+		ctrlsp[0] = NULL;
+		rs->sr_err = LDAP_OTHER;
+	}
+
+	ber_free_buf( ber );
+
+	return rs->sr_err;
+}
+
+static int pack_sss_response_control(
+	Operation		*op,
+	SlapReply		*rs,
+	LDAPControl	**ctrlsp )
+{
+	LDAPControl			*ctrl;
+	BerElementBuffer	berbuf;
+	BerElement			*ber		= (BerElement *)&berbuf;
+	struct berval		bv;
+	int					rc;
+
+	ber_init2( ber, NULL, LBER_USE_DER );
+	ber_set_option( ber, LBER_OPT_BER_MEMCTX, &op->o_tmpmemctx );
+
+	/* Pack error code */
+	rc = ber_printf(ber, "{e}", rs->sr_err);
+
+	if ( rc != -1)
+		rc = ber_flatten2( ber, &bv, 0 );
+
+	if ( rc != -1 ) {
+		ctrl = (LDAPControl *)op->o_tmpalloc( sizeof(LDAPControl)+
+			bv.bv_len, op->o_tmpmemctx );
+		ctrl->ldctl_oid			= LDAP_CONTROL_SORTRESPONSE;
+		ctrl->ldctl_iscritical	= 0;
+		ctrl->ldctl_value.bv_val = (char *)(ctrl+1);
+		ctrl->ldctl_value.bv_len = bv.bv_len;
+		AC_MEMCPY( ctrl->ldctl_value.bv_val, bv.bv_val, bv.bv_len );
+		ctrlsp[0] = ctrl;
+	} else {
+		ctrlsp[0] = NULL;
+		rs->sr_err = LDAP_OTHER;
+	}
+
+	ber_free_buf( ber );
+
+	return rs->sr_err;
+}
+
+/* Return the session id or -1 if unknown */
+static int find_session_by_so(
+	int svi_max_percon,
+	int conn_id,
+	sort_op *so )
+{
+	int sess_id;
+	if (so == NULL) {
+		return -1;
+	}
+	for (sess_id = 0; sess_id < svi_max_percon; sess_id++) {
+		if ( sort_conns[conn_id] && sort_conns[conn_id][sess_id] == so )
+			return sess_id;
+	}
+	return -1;
+}
+
+/* Return the session id or -1 if unknown */
+static int find_session_by_context(
+	int svi_max_percon,
+	int conn_id,
+	unsigned long vc_context,
+	PagedResultsCookie ps_cookie )
+{
+	int sess_id;
+	for(sess_id = 0; sess_id < svi_max_percon; sess_id++) {
+		if( sort_conns[conn_id] && sort_conns[conn_id][sess_id] &&
+		    ( sort_conns[conn_id][sess_id]->so_vcontext == vc_context || 
+                      (PagedResultsCookie) sort_conns[conn_id][sess_id]->so_tree == ps_cookie ) )
+			return sess_id;
+	}
+	return -1;
+}
+
+static int find_next_session(
+	int svi_max_percon,
+	int conn_id )
+{
+	int sess_id;
+	assert(sort_conns[conn_id] != NULL);
+	for(sess_id = 0; sess_id < svi_max_percon; sess_id++) {
+		if(!sort_conns[conn_id][sess_id]) {
+			return sess_id;
+		}
+	}
+	if (sess_id >= svi_max_percon) {
+		return -1;
+	} else {
+		return sess_id;
+	}
+}
+	
+static void free_sort_op( Connection *conn, sort_op *so )
+{
+	int sess_id;
+		
+	ldap_pvt_thread_mutex_lock( &sort_conns_mutex );
+	sess_id = find_session_by_so( so->so_info->svi_max_percon, conn->c_conn_idx, so );
+	if ( sess_id > -1 ) {
+	    sort_conns[conn->c_conn_idx][sess_id] = NULL;
+	    so->so_info->svi_num--;
+	}
+	ldap_pvt_thread_mutex_unlock( &sort_conns_mutex );
+	
+	if ( sess_id > -1 ){
+	    if ( so->so_tree ) {
+		    if ( so->so_paged > SLAP_CONTROL_IGNORED ) {
+			    Avlnode *cur_node, *next_node;
+			    cur_node = so->so_tree;
+			    while ( cur_node ) {
+				    next_node = tavl_next( cur_node, TAVL_DIR_RIGHT );
+				    ch_free( cur_node->avl_data );
+				    ber_memfree( cur_node );
+
+				    cur_node = next_node;
+			    }
+		    } else {
+			    tavl_free( so->so_tree, ch_free );
+		    }
+		    so->so_tree = NULL;
+	    }
+
+	    ch_free( so );
+	}
+}
+
+static void free_sort_ops( Connection *conn, sort_op **sos, int svi_max_percon )
+{
+	int sess_id;
+	sort_op *so;
+
+	for( sess_id = 0; sess_id < svi_max_percon ; sess_id++ ) {
+		so = sort_conns[conn->c_conn_idx][sess_id];
+		if ( so ) {
+			free_sort_op( conn, so );
+			sort_conns[conn->c_conn_idx][sess_id] = NULL;
+		}
+	}
+}
+	
+static void send_list(
+	Operation		*op,
+	SlapReply		*rs,
+	sort_op			*so)
+{
+	Avlnode	*cur_node, *tmp_node;
+	vlv_ctrl *vc = op->o_controls[vlv_cid];
+	int i, j, dir, rc;
+	BackendDB *be;
+	Entry *e;
+	LDAPControl *ctrls[2];
+
+	rs->sr_attrs = op->ors_attrs;
+
+	/* FIXME: it may be better to just flatten the tree into
+	 * an array before doing all of this...
+	 */
+
+	/* Are we just counting an offset? */
+	if ( BER_BVISNULL( &vc->vc_value )) {
+		if ( vc->vc_offset == vc->vc_count ) {
+			/* wants the last entry in the list */
+			cur_node = tavl_end(so->so_tree, TAVL_DIR_RIGHT);
+			so->so_vlv_target = so->so_nentries;
+		} else if ( vc->vc_offset == 1 ) {
+			/* wants the first entry in the list */
+			cur_node = tavl_end(so->so_tree, TAVL_DIR_LEFT);
+			so->so_vlv_target = 1;
+		} else {
+			int target;
+			/* Just iterate to the right spot */
+			if ( vc->vc_count && vc->vc_count != so->so_nentries ) {
+				if ( vc->vc_offset > vc->vc_count )
+					goto range_err;
+				target = so->so_nentries * vc->vc_offset / vc->vc_count;
+			} else {
+				if ( vc->vc_offset > so->so_nentries ) {
+range_err:
+					so->so_vlv_rc = LDAP_VLV_RANGE_ERROR;
+					pack_vlv_response_control( op, rs, so, ctrls );
+					ctrls[1] = NULL;
+					slap_add_ctrls( op, rs, ctrls );
+					rs->sr_err = LDAP_VLV_ERROR;
+					return;
+				}
+				target = vc->vc_offset;
+			}
+			so->so_vlv_target = target;
+			/* Start at left and go right, or start at right and go left? */
+			if ( target < so->so_nentries / 2 ) {
+				cur_node = tavl_end(so->so_tree, TAVL_DIR_LEFT);
+				dir = TAVL_DIR_RIGHT;
+			} else {
+				cur_node = tavl_end(so->so_tree, TAVL_DIR_RIGHT);
+				dir = TAVL_DIR_LEFT;
+				target = so->so_nentries - target + 1;
+			}
+			for ( i=1; i<target; i++ )
+				cur_node = tavl_next( cur_node, dir );
+		}
+	} else {
+	/* we're looking for a specific value */
+		sort_ctrl *sc = so->so_ctrl;
+		MatchingRule *mr = sc->sc_keys[0].sk_ordering;
+		sort_node *sn;
+		struct berval bv;
+
+		if ( mr->smr_normalize ) {
+			rc = mr->smr_normalize( SLAP_MR_VALUE_OF_SYNTAX,
+				mr->smr_syntax, mr, &vc->vc_value, &bv, op->o_tmpmemctx );
+			if ( rc ) {
+				so->so_vlv_rc = LDAP_INAPPROPRIATE_MATCHING;
+				pack_vlv_response_control( op, rs, so, ctrls );
+				ctrls[1] = NULL;
+				slap_add_ctrls( op, rs, ctrls );
+				rs->sr_err = LDAP_VLV_ERROR;
+				return;
+			}
+		} else {
+			bv = vc->vc_value;
+		}
+
+		sn = op->o_tmpalloc( sizeof(sort_node) +
+			sc->sc_nkeys * sizeof(struct berval), op->o_tmpmemctx );
+		sn->sn_vals = (struct berval *)(sn+1);
+		sn->sn_conn = op->o_conn->c_conn_idx;
+		sn->sn_session = find_session_by_so( so->so_info->svi_max_percon, op->o_conn->c_conn_idx, so );
+		sn->sn_vals[0] = bv;
+		for (i=1; i<sc->sc_nkeys; i++) {
+			BER_BVZERO( &sn->sn_vals[i] );
+		}
+		cur_node = tavl_find3( so->so_tree, sn, node_cmp, &j );
+		/* didn't find >= match */
+		if ( j > 0 ) {
+			if ( cur_node )
+				cur_node = tavl_next( cur_node, TAVL_DIR_RIGHT );
+		}
+		op->o_tmpfree( sn, op->o_tmpmemctx );
+
+		if ( !cur_node ) {
+			so->so_vlv_target = so->so_nentries + 1;
+		} else {
+			sort_node *sn = so->so_tree->avl_data;
+			/* start from the left or the right side? */
+			mr->smr_match( &i, 0, mr->smr_syntax, mr, &bv, &sn->sn_vals[0] );
+			if ( i > 0 ) {
+				tmp_node = tavl_end(so->so_tree, TAVL_DIR_RIGHT);
+				dir = TAVL_DIR_LEFT;
+			} else {
+				tmp_node = tavl_end(so->so_tree, TAVL_DIR_LEFT);
+				dir = TAVL_DIR_RIGHT;
+			}
+			for (i=0; tmp_node != cur_node;
+				tmp_node = tavl_next( tmp_node, dir ), i++);
+			so->so_vlv_target = (dir == TAVL_DIR_RIGHT) ? i+1 : so->so_nentries - i;
+		}
+		if ( bv.bv_val != vc->vc_value.bv_val )
+			op->o_tmpfree( bv.bv_val, op->o_tmpmemctx );
+	}
+	if ( !cur_node ) {
+		i = 1;
+		cur_node = tavl_end(so->so_tree, TAVL_DIR_RIGHT);
+	} else {
+		i = 0;
+	}
+	for ( ; i<vc->vc_before; i++ ) {
+		tmp_node = tavl_next( cur_node, TAVL_DIR_LEFT );
+		if ( !tmp_node ) break;
+		cur_node = tmp_node;
+	}
+	j = i + vc->vc_after + 1;
+	be = op->o_bd;
+	for ( i=0; i<j; i++ ) {
+		sort_node *sn = cur_node->avl_data;
+
+		if ( slapd_shutdown ) break;
+
+		op->o_bd = select_backend( &sn->sn_dn, 0 );
+		e = NULL;
+		rc = be_entry_get_rw( op, &sn->sn_dn, NULL, NULL, 0, &e );
+
+		if ( e && rc == LDAP_SUCCESS ) {
+			rs->sr_entry = e;
+			rs->sr_flags = REP_ENTRY_MUSTRELEASE;
+			rs->sr_err = send_search_entry( op, rs );
+			if ( rs->sr_err == LDAP_UNAVAILABLE )
+				break;
+		}
+		cur_node = tavl_next( cur_node, TAVL_DIR_RIGHT );
+		if ( !cur_node ) break;
+	}
+	so->so_vlv_rc = LDAP_SUCCESS;
+
+	op->o_bd = be;
+}
+
+static void send_page( Operation *op, SlapReply *rs, sort_op *so )
+{
+	Avlnode		*cur_node		= so->so_tree;
+	Avlnode		*next_node		= NULL;
+	BackendDB *be = op->o_bd;
+	Entry *e;
+	int rc;
+
+	rs->sr_attrs = op->ors_attrs;
+
+	while ( cur_node && rs->sr_nentries < so->so_page_size ) {
+		sort_node *sn = cur_node->avl_data;
+
+		if ( slapd_shutdown ) break;
+
+		next_node = tavl_next( cur_node, TAVL_DIR_RIGHT );
+
+		op->o_bd = select_backend( &sn->sn_dn, 0 );
+		e = NULL;
+		rc = be_entry_get_rw( op, &sn->sn_dn, NULL, NULL, 0, &e );
+
+		ch_free( cur_node->avl_data );
+		ber_memfree( cur_node );
+
+		cur_node = next_node;
+		so->so_nentries--;
+
+		if ( e && rc == LDAP_SUCCESS ) {
+			rs->sr_entry = e;
+			rs->sr_flags = REP_ENTRY_MUSTRELEASE;
+			rs->sr_err = send_search_entry( op, rs );
+			if ( rs->sr_err == LDAP_UNAVAILABLE )
+				break;
+		}
+	}
+
+	/* Set the first entry to send for the next page */
+	so->so_tree = next_node;
+	if ( next_node )
+		next_node->avl_left = NULL;
+
+	op->o_bd = be;
+}
+
+static void send_entry(
+	Operation		*op,
+	SlapReply		*rs,
+	sort_op			*so)
+{
+	Debug(LDAP_DEBUG_TRACE,
+		"%s: response control: status=%d, text=%s\n",
+		debug_header, rs->sr_err, SAFESTR(rs->sr_text, "<None>"));
+
+	if ( !so->so_tree )
+		return;
+
+	/* RFC 2891: If critical then send the entries iff they were
+	 * succesfully sorted.  If non-critical send all entries
+	 * whether they were sorted or not.
+	 */
+	if ( (op->o_ctrlflag[sss_cid] != SLAP_CONTROL_CRITICAL) ||
+		 (rs->sr_err == LDAP_SUCCESS) )
+	{
+		if ( so->so_vlv > SLAP_CONTROL_IGNORED ) {
+			send_list( op, rs, so );
+		} else {
+			/* Get the first node to send */
+			Avlnode *start_node = tavl_end(so->so_tree, TAVL_DIR_LEFT);
+			so->so_tree = start_node;
+
+			if ( so->so_paged <= SLAP_CONTROL_IGNORED ) {
+				/* Not paged result search.  Send all entries.
+				 * Set the page size to the number of entries
+				 * so that send_page() will send all entries.
+				 */
+				so->so_page_size = so->so_nentries;
+			}
+
+			send_page( op, rs, so );
+		}
+	}
+}
+
+static void send_result(
+	Operation		*op,
+	SlapReply		*rs,
+	sort_op			*so)
+{
+	LDAPControl *ctrls[3];
+	int rc, i = 0;
+
+	rc = pack_sss_response_control( op, rs, ctrls );
+	if ( rc == LDAP_SUCCESS ) {
+		i++;
+		rc = -1;
+		if ( so->so_paged > SLAP_CONTROL_IGNORED ) {
+			rc = pack_pagedresult_response_control( op, rs, so, ctrls+1 );
+		} else if ( so->so_vlv > SLAP_CONTROL_IGNORED ) {
+			rc = pack_vlv_response_control( op, rs, so, ctrls+1 );
+		}
+		if ( rc == LDAP_SUCCESS )
+			i++;
+	}
+	ctrls[i] = NULL;
+
+	if ( ctrls[0] != NULL )
+		slap_add_ctrls( op, rs, ctrls );
+	send_ldap_result( op, rs );
+
+	if ( so->so_tree == NULL ) {
+		/* Search finished, so clean up */
+		free_sort_op( op->o_conn, so );
+	} else {
+	    so->so_running = 0;
+	}
+}
+
+static int sssvlv_op_response(
+	Operation	*op,
+	SlapReply	*rs )
+{
+	sort_ctrl *sc = op->o_controls[sss_cid];
+	sort_op *so = op->o_callback->sc_private;
+
+	if ( rs->sr_type == REP_SEARCH ) {
+		int i;
+		size_t len;
+		sort_node *sn, *sn2;
+		struct berval *bv;
+		char *ptr;
+
+		len = sizeof(sort_node) + sc->sc_nkeys * sizeof(struct berval) +
+			rs->sr_entry->e_nname.bv_len + 1;
+		sn = op->o_tmpalloc( len, op->o_tmpmemctx );
+		sn->sn_vals = (struct berval *)(sn+1);
+
+		/* Build tmp list of key values */
+		for ( i=0; i<sc->sc_nkeys; i++ ) {
+			Attribute *a = attr_find( rs->sr_entry->e_attrs,
+				sc->sc_keys[i].sk_ad );
+			if ( a ) {
+				if ( a->a_numvals > 1 ) {
+					bv = select_value( a, &sc->sc_keys[i] );
+				} else {
+					bv = a->a_nvals;
+				}
+				sn->sn_vals[i] = *bv;
+				len += bv->bv_len + 1;
+			} else {
+				BER_BVZERO( &sn->sn_vals[i] );
+			}
+		}
+
+		/* Now dup into regular memory */
+		sn2 = ch_malloc( len );
+		sn2->sn_vals = (struct berval *)(sn2+1);
+		AC_MEMCPY( sn2->sn_vals, sn->sn_vals,
+				sc->sc_nkeys * sizeof(struct berval));
+
+		ptr = (char *)(sn2->sn_vals + sc->sc_nkeys);
+		sn2->sn_dn.bv_val = ptr;
+		sn2->sn_dn.bv_len = rs->sr_entry->e_nname.bv_len;
+		AC_MEMCPY( ptr, rs->sr_entry->e_nname.bv_val,
+			rs->sr_entry->e_nname.bv_len );
+		ptr += rs->sr_entry->e_nname.bv_len;
+		*ptr++ = '\0';
+		for ( i=0; i<sc->sc_nkeys; i++ ) {
+			if ( !BER_BVISNULL( &sn2->sn_vals[i] )) {
+				AC_MEMCPY(ptr, sn2->sn_vals[i].bv_val, sn2->sn_vals[i].bv_len);
+				sn2->sn_vals[i].bv_val = ptr;
+				ptr += sn2->sn_vals[i].bv_len;
+				*ptr++ = '\0';
+			}
+		}
+		op->o_tmpfree( sn, op->o_tmpmemctx );
+		sn = sn2;
+		sn->sn_conn = op->o_conn->c_conn_idx;
+		sn->sn_session = find_session_by_so( so->so_info->svi_max_percon, op->o_conn->c_conn_idx, so );
+
+		/* Insert into the AVL tree */
+		tavl_insert(&(so->so_tree), sn, node_insert, avl_dup_error);
+
+		so->so_nentries++;
+
+		/* Collected the keys so that they can be sorted.  Thus, stop
+		 * the entry from propagating.
+		 */
+		rs->sr_err = LDAP_SUCCESS;
+	}
+	else if ( rs->sr_type == REP_RESULT ) {
+		/* Remove serversort response callback.
+		 * We don't want the entries that we are about to send to be
+		 * processed by serversort response again.
+		 */
+		if ( op->o_callback->sc_response == sssvlv_op_response ) {
+			op->o_callback = op->o_callback->sc_next;
+		}
+
+		send_entry( op, rs, so );
+		send_result( op, rs, so );
+	}
+
+	return rs->sr_err;
+}
+
+static int sssvlv_op_search(
+	Operation		*op,
+	SlapReply		*rs)
+{
+	slap_overinst			*on			= (slap_overinst *)op->o_bd->bd_info;
+	sssvlv_info				*si			= on->on_bi.bi_private;
+	int						rc			= SLAP_CB_CONTINUE;
+	int	ok;
+	sort_op *so = NULL, so2;
+	sort_ctrl *sc;
+	PagedResultsState *ps;
+	vlv_ctrl *vc;
+	int sess_id;
+
+	if ( op->o_ctrlflag[sss_cid] <= SLAP_CONTROL_IGNORED ) {
+		if ( op->o_ctrlflag[vlv_cid] > SLAP_CONTROL_IGNORED ) {
+			LDAPControl *ctrls[2];
+			so2.so_vcontext = 0;
+			so2.so_vlv_target = 0;
+			so2.so_nentries = 0;
+			so2.so_vlv_rc = LDAP_VLV_SSS_MISSING;
+			so2.so_vlv = op->o_ctrlflag[vlv_cid];
+			rc = pack_vlv_response_control( op, rs, &so2, ctrls );
+			if ( rc == LDAP_SUCCESS ) {
+				ctrls[1] = NULL;
+				slap_add_ctrls( op, rs, ctrls );
+			}
+			rs->sr_err = LDAP_VLV_ERROR;
+			rs->sr_text = "Sort control is required with VLV";
+			goto leave;
+		}
+		/* Not server side sort so just continue */
+		return SLAP_CB_CONTINUE;
+	}
+
+	Debug(LDAP_DEBUG_TRACE,
+		"==> sssvlv_search: <%s> %s, control flag: %d\n",
+		op->o_req_dn.bv_val, op->ors_filterstr.bv_val,
+		op->o_ctrlflag[sss_cid]);
+
+	sc = op->o_controls[sss_cid];
+	if ( sc->sc_nkeys > si->svi_max_keys ) {
+		rs->sr_text = "Too many sort keys";
+		rs->sr_err = LDAP_UNWILLING_TO_PERFORM;
+		goto leave;
+	}
+
+	ps = ( op->o_pagedresults > SLAP_CONTROL_IGNORED ) ?
+		(PagedResultsState*)(op->o_pagedresults_state) : NULL;
+	vc = op->o_ctrlflag[vlv_cid] > SLAP_CONTROL_IGNORED ?
+		op->o_controls[vlv_cid] : NULL;
+
+	if ( ps && vc ) {
+		rs->sr_text = "VLV incompatible with PagedResults";
+		rs->sr_err = LDAP_UNWILLING_TO_PERFORM;
+		goto leave;
+	}
+
+	ok = 1;
+	ldap_pvt_thread_mutex_lock( &sort_conns_mutex );
+	/* Is there already a sort running on this conn? */
+	sess_id = find_session_by_context( si->svi_max_percon, op->o_conn->c_conn_idx, vc ? vc->vc_context : NO_VC_CONTEXT, ps ? ps->ps_cookie : NO_PS_COOKIE );
+	if ( sess_id >= 0 ) {
+		so = sort_conns[op->o_conn->c_conn_idx][sess_id];
+		
+		if( so->so_running > 0 ){
+		    /* another thread is handling, response busy to client */
+		    so = NULL;
+		    ok = 0;
+		} else {
+		
+		    /* Is it a continuation of a VLV search? */
+		    if ( !vc || so->so_vlv <= SLAP_CONTROL_IGNORED ||
+			    vc->vc_context != so->so_vcontext ) {
+			    /* Is it a continuation of a paged search? */
+			    if ( !ps || so->so_paged <= SLAP_CONTROL_IGNORED ||
+				    op->o_conn->c_pagedresults_state.ps_cookie != ps->ps_cookie ) {
+				    ok = 0;
+			    } else if ( !ps->ps_size ) {
+			    /* Abandoning current request */
+				    ok = 0;
+				    so->so_nentries = 0;
+				    rs->sr_err = LDAP_SUCCESS;
+			    }
+		    }
+		    if (( vc && so->so_paged > SLAP_CONTROL_IGNORED ) ||
+			    ( ps && so->so_vlv > SLAP_CONTROL_IGNORED )) {
+			    /* changed from paged to vlv or vice versa, abandon */
+			    ok = 0;
+			    so->so_nentries = 0;
+			    rs->sr_err = LDAP_UNWILLING_TO_PERFORM;
+		    }
+
+		    if ( ok ) {
+			/* occupy before mutex unlock */
+			so->so_running = 1;
+		    }
+		
+		}
+	/* Are there too many running overall? */
+	} else if ( si->svi_num >= si->svi_max ) {
+		ok = 0;
+	} else if ( ( sess_id = find_next_session(si->svi_max_percon, op->o_conn->c_conn_idx ) ) < 0 ) {
+		ok = 0;
+	} else {
+		/* OK, this connection now has a sort running */
+		si->svi_num++;
+		sort_conns[op->o_conn->c_conn_idx][sess_id] = &so2;
+		sort_conns[op->o_conn->c_conn_idx][sess_id]->so_session = sess_id;
+	}
+	ldap_pvt_thread_mutex_unlock( &sort_conns_mutex );
+	if ( ok ) {
+		/* If we're a global overlay, this check got bypassed */
+		if ( !op->ors_limit && limits_check( op, rs ))
+			return rs->sr_err;
+		/* are we continuing a VLV search? */
+		if ( so && vc && vc->vc_context ) {
+			so->so_ctrl = sc;
+			send_list( op, rs, so );
+			send_result( op, rs, so );
+			rc = LDAP_SUCCESS;
+		/* are we continuing a paged search? */
+		} else if ( so && ps && ps->ps_cookie ) {
+			so->so_ctrl = sc;
+			send_page( op, rs, so );
+			send_result( op, rs, so );
+			rc = LDAP_SUCCESS;
+		} else {
+			slap_callback *cb = op->o_tmpalloc( sizeof(slap_callback),
+				op->o_tmpmemctx );
+			/* Install serversort response callback to handle a new search */
+			if ( ps || vc ) {
+				so = ch_calloc( 1, sizeof(sort_op));
+			} else {
+				so = op->o_tmpcalloc( 1, sizeof(sort_op), op->o_tmpmemctx );
+			}
+			sort_conns[op->o_conn->c_conn_idx][sess_id] = so;
+
+			cb->sc_cleanup		= NULL;
+			cb->sc_response		= sssvlv_op_response;
+			cb->sc_next			= op->o_callback;
+			cb->sc_private		= so;
+			cb->sc_writewait	= NULL;
+
+			so->so_tree = NULL;
+			so->so_ctrl = sc;
+			so->so_info = si;
+			if ( ps ) {
+				so->so_paged = op->o_pagedresults;
+				so->so_page_size = ps->ps_size;
+				op->o_pagedresults = SLAP_CONTROL_IGNORED;
+			} else {
+				so->so_paged = 0;
+				so->so_page_size = 0;
+				if ( vc ) {
+					so->so_vlv = op->o_ctrlflag[vlv_cid];
+					so->so_vlv_target = 0;
+					so->so_vlv_rc = 0;
+				} else {
+					so->so_vlv = SLAP_CONTROL_NONE;
+				}
+			}
+			so->so_session = sess_id;
+			so->so_vlv = op->o_ctrlflag[vlv_cid];
+			so->so_vcontext = (unsigned long)so;
+			so->so_nentries = 0;
+			so->so_running = 1;
+
+			op->o_callback		= cb;
+		}
+	} else {
+		if ( so && !so->so_nentries ) {
+			free_sort_op( op->o_conn, so );
+		} else {
+			rs->sr_text = "Other sort requests already in progress";
+			rs->sr_err = LDAP_BUSY;
+		}
+leave:
+		rc = rs->sr_err;
+		send_ldap_result( op, rs );
+	}
+
+	return rc;
+}
+
+static int get_ordering_rule(
+	AttributeDescription	*ad,
+	struct berval			*matchrule,
+	SlapReply				*rs,
+	MatchingRule			**ordering )
+{
+	MatchingRule* mr;
+
+	if ( matchrule && matchrule->bv_val ) {
+		mr = mr_find( matchrule->bv_val );
+		if ( mr == NULL ) {
+			rs->sr_err = LDAP_INAPPROPRIATE_MATCHING;
+			rs->sr_text = "serverSort control: No ordering rule";
+			Debug(LDAP_DEBUG_TRACE, "%s: no ordering rule function for %s\n",
+				debug_header, matchrule->bv_val, 0);
+		}
+	}
+	else {
+		mr = ad->ad_type->sat_ordering;
+		if ( mr == NULL ) {
+			rs->sr_err = LDAP_INAPPROPRIATE_MATCHING;
+			rs->sr_text = "serverSort control: No ordering rule";
+			Debug(LDAP_DEBUG_TRACE,
+				"%s: no ordering rule specified and no default ordering rule for attribute %s\n",
+				debug_header, ad->ad_cname.bv_val, 0);
+		}
+	}
+
+	*ordering = mr;
+	return rs->sr_err;
+}
+
+static int count_key(BerElement *ber)
+{
+	char *end;
+	ber_len_t len;
+	ber_tag_t tag;
+	int count = 0;
+
+	/* Server Side Sort Control is a SEQUENCE of SEQUENCE */
+	for ( tag = ber_first_element( ber, &len, &end );
+		  tag == LBER_SEQUENCE;
+		  tag = ber_next_element( ber, &len, end ))
+	{
+		tag = ber_skip_tag( ber, &len );
+		ber_skip_data( ber, len );
+		++count;
+	}
+	ber_rewind( ber );
+
+	return count;
+}
+
+static int build_key(
+	BerElement		*ber,
+	SlapReply		*rs,
+	sort_key			*key )
+{
+	struct berval attr;
+	struct berval matchrule = BER_BVNULL;
+	ber_int_t reverse = 0;
+	ber_tag_t tag;
+	ber_len_t len;
+	MatchingRule *ordering = NULL;
+	AttributeDescription *ad = NULL;
+	const char *text;
+
+	if (( tag = ber_scanf( ber, "{" )) == LBER_ERROR ) {
+		rs->sr_text = "serverSort control: decoding error";
+		rs->sr_err = LDAP_PROTOCOL_ERROR;
+		return rs->sr_err;
+	}
+
+	if (( tag = ber_scanf( ber, "m", &attr )) == LBER_ERROR ) {
+		rs->sr_text = "serverSort control: attribute decoding error";
+		rs->sr_err = LDAP_PROTOCOL_ERROR;
+		return rs->sr_err;
+	}
+
+	tag = ber_peek_tag( ber, &len );
+	if ( tag == LDAP_MATCHRULE_IDENTIFIER ) {
+		if (( tag = ber_scanf( ber, "m", &matchrule )) == LBER_ERROR ) {
+			rs->sr_text = "serverSort control: matchrule decoding error";
+			rs->sr_err = LDAP_PROTOCOL_ERROR;
+			return rs->sr_err;
+		}
+		tag = ber_peek_tag( ber, &len );
+	}
+
+	if ( tag == LDAP_REVERSEORDER_IDENTIFIER ) {
+		if (( tag = ber_scanf( ber, "b", &reverse )) == LBER_ERROR ) {
+			rs->sr_text = "serverSort control: reverse decoding error";
+			rs->sr_err = LDAP_PROTOCOL_ERROR;
+			return rs->sr_err;
+		}
+	}
+
+	if (( tag = ber_scanf( ber, "}" )) == LBER_ERROR ) {
+		rs->sr_text = "serverSort control: decoding error";
+		rs->sr_err = LDAP_PROTOCOL_ERROR;
+		return rs->sr_err;
+	}
+
+	if ( slap_bv2ad( &attr, &ad, &text ) != LDAP_SUCCESS ) {
+		rs->sr_text =
+			"serverSort control: Unrecognized attribute type in sort key";
+		Debug(LDAP_DEBUG_TRACE,
+			"%s: Unrecognized attribute type in sort key: %s\n",
+			debug_header, SAFESTR(attr.bv_val, "<None>"), 0);
+		rs->sr_err = LDAP_NO_SUCH_ATTRIBUTE;
+		return rs->sr_err;
+	}
+
+	/* get_ordering_rule will set sr_err and sr_text */
+	get_ordering_rule( ad, &matchrule, rs, &ordering );
+	if ( rs->sr_err != LDAP_SUCCESS ) {
+		return rs->sr_err;
+	}
+
+	key->sk_ad = ad;
+	key->sk_ordering = ordering;
+	key->sk_direction = reverse ? -1 : 1;
+
+	return rs->sr_err;
+}
+
+/* Conforms to RFC4510 re: Criticality, original RFC2891 spec is broken
+ * Also see ITS#7253 for discussion
+ */
+static int sss_parseCtrl(
+	Operation		*op,
+	SlapReply		*rs,
+	LDAPControl		*ctrl )
+{
+	BerElementBuffer	berbuf;
+	BerElement			*ber;
+	ber_tag_t		tag;
+	ber_len_t		len;
+	int					i;
+	sort_ctrl	*sc;
+
+	rs->sr_err = LDAP_PROTOCOL_ERROR;
+
+	if ( op->o_ctrlflag[sss_cid] > SLAP_CONTROL_IGNORED ) {
+		rs->sr_text = "sorted results control specified multiple times";
+	} else if ( BER_BVISNULL( &ctrl->ldctl_value ) ) {
+		rs->sr_text = "sorted results control value is absent";
+	} else if ( BER_BVISEMPTY( &ctrl->ldctl_value ) ) {
+		rs->sr_text = "sorted results control value is empty";
+	} else {
+		rs->sr_err = LDAP_SUCCESS;
+	}
+	if ( rs->sr_err != LDAP_SUCCESS )
+		return rs->sr_err;
+
+	op->o_ctrlflag[sss_cid] = ctrl->ldctl_iscritical ?
+		SLAP_CONTROL_CRITICAL : SLAP_CONTROL_NONCRITICAL;
+
+	ber = (BerElement *)&berbuf;
+	ber_init2( ber, &ctrl->ldctl_value, 0 );
+	i = count_key( ber );
+
+	sc = op->o_tmpalloc( sizeof(sort_ctrl) +
+		(i-1) * sizeof(sort_key), op->o_tmpmemctx );
+	sc->sc_nkeys = i;
+	op->o_controls[sss_cid] = sc;
+
+	/* peel off initial sequence */
+	ber_scanf( ber, "{" );
+
+	i = 0;
+	do {
+		if ( build_key( ber, rs, &sc->sc_keys[i] ) != LDAP_SUCCESS )
+			break;
+		i++;
+		tag = ber_peek_tag( ber, &len );
+	} while ( tag != LBER_DEFAULT );
+
+	return rs->sr_err;
+}
+
+static int vlv_parseCtrl(
+	Operation		*op,
+	SlapReply		*rs,
+	LDAPControl		*ctrl )
+{
+	BerElementBuffer	berbuf;
+	BerElement			*ber;
+	ber_tag_t		tag;
+	ber_len_t		len;
+	vlv_ctrl	*vc, vc2;
+
+	rs->sr_err = LDAP_PROTOCOL_ERROR;
+	rs->sr_text = NULL;
+
+	if ( op->o_ctrlflag[vlv_cid] > SLAP_CONTROL_IGNORED ) {
+		rs->sr_text = "vlv control specified multiple times";
+	} else if ( BER_BVISNULL( &ctrl->ldctl_value ) ) {
+		rs->sr_text = "vlv control value is absent";
+	} else if ( BER_BVISEMPTY( &ctrl->ldctl_value ) ) {
+		rs->sr_text = "vlv control value is empty";
+	}
+	if ( rs->sr_text != NULL )
+		return rs->sr_err;
+
+	op->o_ctrlflag[vlv_cid] = ctrl->ldctl_iscritical ?
+		SLAP_CONTROL_CRITICAL : SLAP_CONTROL_NONCRITICAL;
+
+	ber = (BerElement *)&berbuf;
+	ber_init2( ber, &ctrl->ldctl_value, 0 );
+
+	rs->sr_err = LDAP_PROTOCOL_ERROR;
+
+	tag = ber_scanf( ber, "{ii", &vc2.vc_before, &vc2.vc_after );
+	if ( tag == LBER_ERROR ) {
+		return rs->sr_err;
+	}
+
+	tag = ber_peek_tag( ber, &len );
+	if ( tag == LDAP_VLVBYINDEX_IDENTIFIER ) {
+		tag = ber_scanf( ber, "{ii}", &vc2.vc_offset, &vc2.vc_count );
+		if ( tag == LBER_ERROR )
+			return rs->sr_err;
+		BER_BVZERO( &vc2.vc_value );
+	} else if ( tag == LDAP_VLVBYVALUE_IDENTIFIER ) {
+		tag = ber_scanf( ber, "m", &vc2.vc_value );
+		if ( tag == LBER_ERROR || BER_BVISNULL( &vc2.vc_value ))
+			return rs->sr_err;
+	} else {
+		return rs->sr_err;
+	}
+	tag = ber_peek_tag( ber, &len );
+	if ( tag == LDAP_VLVCONTEXT_IDENTIFIER ) {
+		struct berval bv;
+		tag = ber_scanf( ber, "m", &bv );
+		if ( tag == LBER_ERROR || bv.bv_len != sizeof(vc2.vc_context))
+			return rs->sr_err;
+		AC_MEMCPY( &vc2.vc_context, bv.bv_val, bv.bv_len );
+	} else {
+		vc2.vc_context = 0;
+	}
+
+	vc = op->o_tmpalloc( sizeof(vlv_ctrl), op->o_tmpmemctx );
+	*vc = vc2;
+	op->o_controls[vlv_cid] = vc;
+	rs->sr_err = LDAP_SUCCESS;
+
+	return rs->sr_err;
+}
+
+static int sssvlv_connection_destroy( BackendDB *be, Connection *conn )
+{
+	slap_overinst	*on		= (slap_overinst *)be->bd_info;
+	sssvlv_info *si = on->on_bi.bi_private;
+
+	if ( sort_conns[conn->c_conn_idx] ) {
+		free_sort_ops( conn, sort_conns[conn->c_conn_idx], si->svi_max_percon );
+	}
+
+	return LDAP_SUCCESS;
+}
+
+static int sssvlv_db_open(
+	BackendDB		*be,
+	ConfigReply		*cr )
+{
+	slap_overinst	*on = (slap_overinst *)be->bd_info;
+	sssvlv_info *si = on->on_bi.bi_private;
+	int rc;
+	int conn_index;
+
+	/* If not set, default to 1/2 of available threads */
+	if ( !si->svi_max )
+		si->svi_max = connection_pool_max / 2;
+
+	if ( dtblsize && !sort_conns ) {
+		ldap_pvt_thread_mutex_init( &sort_conns_mutex );
+		/* accommodate for c_conn_idx == -1 */
+		sort_conns = ch_calloc( dtblsize + 1, sizeof(sort_op **) );
+		for ( conn_index = 0 ; conn_index < dtblsize + 1 ; conn_index++ ) {
+			sort_conns[conn_index] = ch_calloc( si->svi_max_percon, sizeof(sort_op *) );
+		}
+		sort_conns++;
+	}
+
+	rc = overlay_register_control( be, LDAP_CONTROL_SORTREQUEST );
+	if ( rc == LDAP_SUCCESS )
+		rc = overlay_register_control( be, LDAP_CONTROL_VLVREQUEST );
+	return rc;
+}
+
+static ConfigTable sssvlv_cfg[] = {
+	{ "sssvlv-max", "num",
+		2, 2, 0, ARG_INT|ARG_OFFSET,
+			(void *)offsetof(sssvlv_info, svi_max),
+		"( OLcfgOvAt:21.1 NAME 'olcSssVlvMax' "
+			"DESC 'Maximum number of concurrent Sort requests' "
+			"SYNTAX OMsInteger SINGLE-VALUE )", NULL, NULL },
+	{ "sssvlv-maxkeys", "num",
+		2, 2, 0, ARG_INT|ARG_OFFSET,
+			(void *)offsetof(sssvlv_info, svi_max_keys),
+		"( OLcfgOvAt:21.2 NAME 'olcSssVlvMaxKeys' "
+			"DESC 'Maximum number of Keys in a Sort request' "
+			"SYNTAX OMsInteger SINGLE-VALUE )", NULL, NULL },
+	{ "sssvlv-maxperconn", "num",
+		2, 2, 0, ARG_INT|ARG_OFFSET,
+			(void *)offsetof(sssvlv_info, svi_max_percon),
+		"( OLcfgOvAt:21.3 NAME 'olcSssVlvMaxPerConn' "
+			"DESC 'Maximum number of concurrent paged search requests per connection' "
+			"SYNTAX OMsInteger SINGLE-VALUE )", NULL, NULL },
+	{ NULL, NULL, 0, 0, 0, ARG_IGNORED }
+};
+
+static ConfigOCs sssvlv_ocs[] = {
+	{ "( OLcfgOvOc:21.1 "
+		"NAME 'olcSssVlvConfig' "
+		"DESC 'SSS VLV configuration' "
+		"SUP olcOverlayConfig "
+		"MAY ( olcSssVlvMax $ olcSssVlvMaxKeys $ olcSssVlvMaxPerConn ) )",
+		Cft_Overlay, sssvlv_cfg, NULL, NULL },
+	{ NULL, 0, NULL }
+};
+
+static int sssvlv_db_init(
+	BackendDB		*be,
+	ConfigReply		*cr)
+{
+	slap_overinst	*on = (slap_overinst *)be->bd_info;
+	sssvlv_info *si;
+
+	if ( ov_count == 0 ) {
+		int rc;
+
+		rc = register_supported_control2( LDAP_CONTROL_SORTREQUEST,
+			SLAP_CTRL_SEARCH,
+			NULL,
+			sss_parseCtrl,
+			1 /* replace */,
+			&sss_cid );
+		if ( rc != LDAP_SUCCESS ) {
+			Debug( LDAP_DEBUG_ANY, "Failed to register Sort Request control '%s' (%d)\n",
+				LDAP_CONTROL_SORTREQUEST, rc, 0 );
+			return rc;
+		}
+
+		rc = register_supported_control2( LDAP_CONTROL_VLVREQUEST,
+			SLAP_CTRL_SEARCH,
+			NULL,
+			vlv_parseCtrl,
+			1 /* replace */,
+			&vlv_cid );
+		if ( rc != LDAP_SUCCESS ) {
+			Debug( LDAP_DEBUG_ANY, "Failed to register VLV Request control '%s' (%d)\n",
+				LDAP_CONTROL_VLVREQUEST, rc, 0 );
+#ifdef SLAP_CONFIG_DELETE
+			overlay_unregister_control( be, LDAP_CONTROL_SORTREQUEST );
+			unregister_supported_control( LDAP_CONTROL_SORTREQUEST );
+#endif /* SLAP_CONFIG_DELETE */
+			return rc;
+		}
+	}
+	
+	si = (sssvlv_info *)ch_malloc(sizeof(sssvlv_info));
+	on->on_bi.bi_private = si;
+
+	si->svi_max = 0;
+	si->svi_num = 0;
+	si->svi_max_keys = SSSVLV_DEFAULT_MAX_KEYS;
+	si->svi_max_percon = SSSVLV_DEFAULT_MAX_REQUEST_PER_CONN;
+
+	ov_count++;
+
+	return LDAP_SUCCESS;
+}
+
+static int sssvlv_db_destroy(
+	BackendDB		*be,
+	ConfigReply		*cr )
+{
+	slap_overinst	*on = (slap_overinst *)be->bd_info;
+	sssvlv_info *si = (sssvlv_info *)on->on_bi.bi_private;
+	int conn_index;
+
+	ov_count--;
+	if ( !ov_count && sort_conns) {
+		sort_conns--;
+		for ( conn_index = 0 ; conn_index < dtblsize + 1 ; conn_index++ ) {
+			ch_free(sort_conns[conn_index]);
+		}
+		ch_free(sort_conns);
+		ldap_pvt_thread_mutex_destroy( &sort_conns_mutex );
+	}
+
+#ifdef SLAP_CONFIG_DELETE
+	overlay_unregister_control( be, LDAP_CONTROL_SORTREQUEST );
+	overlay_unregister_control( be, LDAP_CONTROL_VLVREQUEST );
+	if ( ov_count == 0 ) {
+		unregister_supported_control( LDAP_CONTROL_SORTREQUEST );
+		unregister_supported_control( LDAP_CONTROL_VLVREQUEST );
+	}
+#endif /* SLAP_CONFIG_DELETE */
+
+	if ( si ) {
+		ch_free( si );
+		on->on_bi.bi_private = NULL;
+	}
+	return LDAP_SUCCESS;
+}
+
+static slap_overinst sssvlv;
+
+int sssvlv_initialize()
+{
+	int rc;
+
+	sssvlv.on_bi.bi_type				= "sssvlv";
+	sssvlv.on_bi.bi_db_init				= sssvlv_db_init;
+	sssvlv.on_bi.bi_db_destroy			= sssvlv_db_destroy;
+	sssvlv.on_bi.bi_db_open				= sssvlv_db_open;
+	sssvlv.on_bi.bi_connection_destroy	= sssvlv_connection_destroy;
+	sssvlv.on_bi.bi_op_search			= sssvlv_op_search;
+
+	sssvlv.on_bi.bi_cf_ocs = sssvlv_ocs;
+
+	rc = config_register_schema( sssvlv_cfg, sssvlv_ocs );
+	if ( rc )
+		return rc;
+
+	rc = overlay_register( &sssvlv );
+	if ( rc != LDAP_SUCCESS ) {
+		Debug( LDAP_DEBUG_ANY, "Failed to register server side sort overlay\n", 0, 0, 0 );
+	}
+
+	return rc;
+}
+
+#if SLAPD_OVER_SSSVLV == SLAPD_MOD_DYNAMIC
+int init_module( int argc, char *argv[])
+{
+	return sssvlv_initialize();
+}
+#endif
+
+#endif /* SLAPD_OVER_SSSVLV */