connection.c

/* $OpenLDAP$ */
/* This work is part of OpenLDAP Software <http://www.openldap.org/>.
 *
 * Copyright 1998-2014 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>.
 */
/* Portions Copyright (c) 1995 Regents of the University of Michigan.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that this notice is preserved and that due credit is given
 * to the University of Michigan at Ann Arbor. The name of the University
 * may not be used to endorse or promote products derived from this
 * software without specific prior written permission. This software
 * is provided ``as is'' without express or implied warranty.
 */

#include "portable.h"

#include <stdio.h>
#ifdef HAVE_LIMITS_H
#include <limits.h>
#endif

#include <ac/socket.h>
#include <ac/errno.h>
#include <ac/string.h>
#include <ac/time.h>
#include <ac/unistd.h>

#include "lutil.h"
#include "slap.h"

#ifdef LDAP_CONNECTIONLESS
#include "../../libraries/liblber/lber-int.h"	/* ber_int_sb_read() */
#endif

#ifdef LDAP_SLAPI
#include "slapi/slapi.h"
#endif

/* protected by connections_mutex */
static ldap_pvt_thread_mutex_t connections_mutex;
static Connection *connections = NULL;

static ldap_pvt_thread_mutex_t conn_nextid_mutex;
static unsigned long conn_nextid = SLAPD_SYNC_SYNCCONN_OFFSET;

static const char conn_lost_str[] = "connection lost";

const char *
connection_state2str( int state )
{
	switch( state ) {
	case SLAP_C_INVALID:	return "!";
	case SLAP_C_INACTIVE:	return "|";
	case SLAP_C_CLOSING:	return "C";
	case SLAP_C_ACTIVE:		return "";
	case SLAP_C_BINDING:	return "B";
	case SLAP_C_CLIENT:		return "L";
	}

	return "?";
}

static Connection* connection_get( ber_socket_t s );

typedef struct conn_readinfo {
	Operation *op;
	ldap_pvt_thread_start_t *func;
	void *arg;
	void *ctx;
	int nullop;
} conn_readinfo;

static int connection_input( Connection *c, conn_readinfo *cri );
static void connection_close( Connection *c );

static int connection_op_activate( Operation *op );
static void connection_op_queue( Operation *op );
static int connection_resched( Connection *conn );
static void connection_abandon( Connection *conn );
static void connection_destroy( Connection *c );

static ldap_pvt_thread_start_t connection_operation;

/*
 * Initialize connection management infrastructure.
 */
int connections_init(void)
{
	int i;

	assert( connections == NULL );

	if( connections != NULL) {
		Debug( LDAP_DEBUG_ANY, "connections_init: already initialized.\n",
			0, 0, 0 );
		return -1;
	}

	/* should check return of every call */
	ldap_pvt_thread_mutex_init( &connections_mutex );
	ldap_pvt_thread_mutex_init( &conn_nextid_mutex );

	connections = (Connection *) ch_calloc( dtblsize, sizeof(Connection) );

	if( connections == NULL ) {
		Debug( LDAP_DEBUG_ANY, "connections_init: "
			"allocation (%d*%ld) of connection array failed\n",
			dtblsize, (long) sizeof(Connection), 0 );
		return -1;
	}

	assert( connections[0].c_struct_state == SLAP_C_UNINITIALIZED );
	assert( connections[dtblsize-1].c_struct_state == SLAP_C_UNINITIALIZED );

	for (i=0; i<dtblsize; i++) connections[i].c_conn_idx = i;

	/*
	 * per entry initialization of the Connection array initialization
	 * will be done by connection_init()
	 */ 

	return 0;
}

/*
 * Destroy connection management infrastructure.
 */

int connections_destroy(void)
{
	ber_socket_t i;

	/* should check return of every call */

	if( connections == NULL) {
		Debug( LDAP_DEBUG_ANY, "connections_destroy: nothing to destroy.\n",
			0, 0, 0 );
		return -1;
	}

	for ( i = 0; i < dtblsize; i++ ) {
		if( connections[i].c_struct_state != SLAP_C_UNINITIALIZED ) {
			ber_sockbuf_free( connections[i].c_sb );
			ldap_pvt_thread_mutex_destroy( &connections[i].c_mutex );
			ldap_pvt_thread_mutex_destroy( &connections[i].c_write1_mutex );
			ldap_pvt_thread_mutex_destroy( &connections[i].c_write2_mutex );
			ldap_pvt_thread_cond_destroy( &connections[i].c_write1_cv );
			ldap_pvt_thread_cond_destroy( &connections[i].c_write2_cv );
#ifdef LDAP_SLAPI
			if ( slapi_plugins_used ) {
				slapi_int_free_object_extensions( SLAPI_X_EXT_CONNECTION,
					&connections[i] );
			}
#endif
		}
	}

	free( connections );
	connections = NULL;

	ldap_pvt_thread_mutex_destroy( &connections_mutex );
	ldap_pvt_thread_mutex_destroy( &conn_nextid_mutex );
	return 0;
}

/*
 * shutdown all connections
 */
int connections_shutdown(void)
{
	ber_socket_t i;

	for ( i = 0; i < dtblsize; i++ ) {
		if( connections[i].c_struct_state != SLAP_C_UNINITIALIZED ) {
			ldap_pvt_thread_mutex_lock( &connections[i].c_mutex );
			if( connections[i].c_struct_state == SLAP_C_USED ) {

				/* give persistent clients a chance to cleanup */
				if( connections[i].c_conn_state == SLAP_C_CLIENT ) {
					ldap_pvt_thread_pool_submit( &connection_pool,
					connections[i].c_clientfunc, connections[i].c_clientarg );
				} else {
					/* c_mutex is locked */
					connection_closing( &connections[i], "slapd shutdown" );
					connection_close( &connections[i] );
				}
			}
			ldap_pvt_thread_mutex_unlock( &connections[i].c_mutex );
		}
	}

	return 0;
}

/*
 * Timeout idle connections.
 */
int connections_timeout_idle(time_t now)
{
	int i = 0, writers = 0;
	ber_socket_t connindex;
	Connection* c;
	time_t old;

	old = slapd_get_writetime();

	for( c = connection_first( &connindex );
		c != NULL;
		c = connection_next( c, &connindex ) )
	{
		/* Don't timeout a slow-running request or a persistent
		 * outbound connection. But if it has a writewaiter, see
		 * if the waiter has been there too long.
		 */
		if(( c->c_n_ops_executing && !c->c_writewaiter)
			|| c->c_conn_state == SLAP_C_CLIENT ) {
			continue;
		}

		if( global_idletimeout && 
			difftime( c->c_activitytime+global_idletimeout, now) < 0 ) {
			/* close it */
			connection_closing( c, "idletimeout" );
			connection_close( c );
			i++;
			continue;
		}
		if ( c->c_writewaiter && global_writetimeout ) {
			writers = 1;
			if( difftime( c->c_activitytime+global_writetimeout, now) < 0 ) {
				/* close it */
				connection_closing( c, "writetimeout" );
				connection_close( c );
				i++;
				continue;
			}
		}
	}
	connection_done( c );
	if ( old && !writers )
		slapd_clr_writetime( old );

	return i;
}

/* Drop all client connections */
void connections_drop()
{
	Connection* c;
	ber_socket_t connindex;

	for( c = connection_first( &connindex );
		c != NULL;
		c = connection_next( c, &connindex ) )
	{
		/* Don't close a slow-running request or a persistent
		 * outbound connection.
		 */
		if(( c->c_n_ops_executing && !c->c_writewaiter)
			|| c->c_conn_state == SLAP_C_CLIENT ) {
			continue;
		}
		connection_closing( c, "dropping" );
		connection_close( c );
	}
	connection_done( c );
}

static Connection* connection_get( ber_socket_t s )
{
	Connection *c;

	Debug( LDAP_DEBUG_ARGS,
		"connection_get(%ld)\n",
		(long) s, 0, 0 );

	assert( connections != NULL );

	if(s == AC_SOCKET_INVALID) return NULL;

	assert( s < dtblsize );
	c = &connections[s];

	if( c != NULL ) {
		ldap_pvt_thread_mutex_lock( &c->c_mutex );

		assert( c->c_struct_state != SLAP_C_UNINITIALIZED );

		if( c->c_struct_state != SLAP_C_USED ) {
			/* connection must have been closed due to resched */

			Debug( LDAP_DEBUG_CONNS,
				"connection_get(%d): connection not used\n",
				s, 0, 0 );
			assert( c->c_conn_state == SLAP_C_INVALID );
			assert( c->c_sd == AC_SOCKET_INVALID );

			ldap_pvt_thread_mutex_unlock( &c->c_mutex );
			return NULL;
		}

		Debug( LDAP_DEBUG_TRACE,
			"connection_get(%d): got connid=%lu\n",
			s, c->c_connid, 0 );

		c->c_n_get++;

		assert( c->c_struct_state == SLAP_C_USED );
		assert( c->c_conn_state != SLAP_C_INVALID );
		assert( c->c_sd != AC_SOCKET_INVALID );

#ifndef SLAPD_MONITOR
		if ( global_idletimeout > 0 )
#endif /* ! SLAPD_MONITOR */
		{
			c->c_activitytime = slap_get_time();
		}
	}

	return c;
}

static void connection_return( Connection *c )
{
	ldap_pvt_thread_mutex_unlock( &c->c_mutex );
}

Connection * connection_init(
	ber_socket_t s,
	Listener *listener,
	const char* dnsname,
	const char* peername,
	int flags,
	slap_ssf_t ssf,
	struct berval *authid
	LDAP_PF_LOCAL_SENDMSG_ARG(struct berval *peerbv))
{
	unsigned long id;
	Connection *c;
	int doinit = 0;
	ber_socket_t sfd = SLAP_FD2SOCK(s);

	assert( connections != NULL );

	assert( listener != NULL );
	assert( dnsname != NULL );
	assert( peername != NULL );

#ifndef HAVE_TLS
	assert( !( flags & CONN_IS_TLS ));
#endif

	if( s == AC_SOCKET_INVALID ) {
		Debug( LDAP_DEBUG_ANY,
			"connection_init: init of socket %ld invalid.\n", (long)s, 0, 0 );
		return NULL;
	}

	assert( s >= 0 );
	assert( s < dtblsize );
	c = &connections[s];
	if( c->c_struct_state == SLAP_C_UNINITIALIZED ) {
		doinit = 1;
	} else {
		assert( c->c_struct_state == SLAP_C_UNUSED );
	}

	if( doinit ) {
		c->c_send_ldap_result = slap_send_ldap_result;
		c->c_send_search_entry = slap_send_search_entry;
		c->c_send_search_reference = slap_send_search_reference;
		c->c_send_ldap_extended = slap_send_ldap_extended;
		c->c_send_ldap_intermediate = slap_send_ldap_intermediate;

		BER_BVZERO( &c->c_authmech );
		BER_BVZERO( &c->c_dn );
		BER_BVZERO( &c->c_ndn );

		c->c_listener = NULL;
		BER_BVZERO( &c->c_peer_domain );
		BER_BVZERO( &c->c_peer_name );

		LDAP_STAILQ_INIT(&c->c_ops);
		LDAP_STAILQ_INIT(&c->c_pending_ops);

#ifdef LDAP_X_TXN
		c->c_txn = CONN_TXN_INACTIVE;
		c->c_txn_backend = NULL;
		LDAP_STAILQ_INIT(&c->c_txn_ops);
#endif

		BER_BVZERO( &c->c_sasl_bind_mech );
		c->c_sasl_done = 0;
		c->c_sasl_authctx = NULL;
		c->c_sasl_sockctx = NULL;
		c->c_sasl_extra = NULL;
		c->c_sasl_bindop = NULL;

		c->c_sb = ber_sockbuf_alloc( );

		{
			ber_len_t max = sockbuf_max_incoming;
			ber_sockbuf_ctrl( c->c_sb, LBER_SB_OPT_SET_MAX_INCOMING, &max );
		}

		c->c_currentber = NULL;

		/* should check status of thread calls */
		ldap_pvt_thread_mutex_init( &c->c_mutex );
		ldap_pvt_thread_mutex_init( &c->c_write1_mutex );
		ldap_pvt_thread_mutex_init( &c->c_write2_mutex );
		ldap_pvt_thread_cond_init( &c->c_write1_cv );
		ldap_pvt_thread_cond_init( &c->c_write2_cv );

#ifdef LDAP_SLAPI
		if ( slapi_plugins_used ) {
			slapi_int_create_object_extensions( SLAPI_X_EXT_CONNECTION, c );
		}
#endif
	}

	ldap_pvt_thread_mutex_lock( &c->c_mutex );

	assert( BER_BVISNULL( &c->c_authmech ) );
	assert( BER_BVISNULL( &c->c_dn ) );
	assert( BER_BVISNULL( &c->c_ndn ) );
	assert( c->c_listener == NULL );
	assert( BER_BVISNULL( &c->c_peer_domain ) );
	assert( BER_BVISNULL( &c->c_peer_name ) );
	assert( LDAP_STAILQ_EMPTY(&c->c_ops) );
	assert( LDAP_STAILQ_EMPTY(&c->c_pending_ops) );
#ifdef LDAP_X_TXN
	assert( c->c_txn == CONN_TXN_INACTIVE );
	assert( c->c_txn_backend == NULL );
	assert( LDAP_STAILQ_EMPTY(&c->c_txn_ops) );
#endif
	assert( BER_BVISNULL( &c->c_sasl_bind_mech ) );
	assert( c->c_sasl_done == 0 );
	assert( c->c_sasl_authctx == NULL );
	assert( c->c_sasl_sockctx == NULL );
	assert( c->c_sasl_extra == NULL );
	assert( c->c_sasl_bindop == NULL );
	assert( c->c_currentber == NULL );
	assert( c->c_writewaiter == 0);
	assert( c->c_writers == 0);

	c->c_listener = listener;
	c->c_sd = s;

	if ( flags & CONN_IS_CLIENT ) {
		c->c_connid = 0;
		ldap_pvt_thread_mutex_lock( &connections_mutex );
		c->c_conn_state = SLAP_C_CLIENT;
		c->c_struct_state = SLAP_C_USED;
		ldap_pvt_thread_mutex_unlock( &connections_mutex );
		c->c_close_reason = "?";			/* should never be needed */
		ber_sockbuf_ctrl( c->c_sb, LBER_SB_OPT_SET_FD, &sfd );
		ldap_pvt_thread_mutex_unlock( &c->c_mutex );

		return c;
	}

	ber_str2bv( dnsname, 0, 1, &c->c_peer_domain );
	ber_str2bv( peername, 0, 1, &c->c_peer_name );

	c->c_n_ops_received = 0;
	c->c_n_ops_executing = 0;
	c->c_n_ops_pending = 0;
	c->c_n_ops_completed = 0;

	c->c_n_get = 0;
	c->c_n_read = 0;
	c->c_n_write = 0;

	/* set to zero until bind, implies LDAP_VERSION3 */
	c->c_protocol = 0;

#ifndef SLAPD_MONITOR
	if ( global_idletimeout > 0 )
#endif /* ! SLAPD_MONITOR */
	{
		c->c_activitytime = c->c_starttime = slap_get_time();
	}

#ifdef LDAP_CONNECTIONLESS
	c->c_is_udp = 0;
	if( flags & CONN_IS_UDP ) {
		c->c_is_udp = 1;
#ifdef LDAP_DEBUG
		ber_sockbuf_add_io( c->c_sb, &ber_sockbuf_io_debug,
			LBER_SBIOD_LEVEL_PROVIDER, (void*)"udp_" );
#endif
		ber_sockbuf_add_io( c->c_sb, &ber_sockbuf_io_udp,
			LBER_SBIOD_LEVEL_PROVIDER, (void *)&sfd );
		ber_sockbuf_add_io( c->c_sb, &ber_sockbuf_io_readahead,
			LBER_SBIOD_LEVEL_PROVIDER, NULL );
	} else
#endif /* LDAP_CONNECTIONLESS */
#ifdef LDAP_PF_LOCAL
	if ( flags & CONN_IS_IPC ) {
#ifdef LDAP_DEBUG
		ber_sockbuf_add_io( c->c_sb, &ber_sockbuf_io_debug,
			LBER_SBIOD_LEVEL_PROVIDER, (void*)"ipc_" );
#endif
		ber_sockbuf_add_io( c->c_sb, &ber_sockbuf_io_fd,
			LBER_SBIOD_LEVEL_PROVIDER, (void *)&sfd );
#ifdef LDAP_PF_LOCAL_SENDMSG
		if ( !BER_BVISEMPTY( peerbv ))
			ber_sockbuf_ctrl( c->c_sb, LBER_SB_OPT_UNGET_BUF, peerbv );
#endif
	} else
#endif /* LDAP_PF_LOCAL */
	{
#ifdef LDAP_DEBUG
		ber_sockbuf_add_io( c->c_sb, &ber_sockbuf_io_debug,
			LBER_SBIOD_LEVEL_PROVIDER, (void*)"tcp_" );
#endif
		ber_sockbuf_add_io( c->c_sb, &ber_sockbuf_io_tcp,
			LBER_SBIOD_LEVEL_PROVIDER, (void *)&sfd );
	}

#ifdef LDAP_DEBUG
	ber_sockbuf_add_io( c->c_sb, &ber_sockbuf_io_debug,
		INT_MAX, (void*)"ldap_" );
#endif

	if( ber_sockbuf_ctrl( c->c_sb, LBER_SB_OPT_SET_NONBLOCK,
		c /* non-NULL */ ) < 0 )
	{
		Debug( LDAP_DEBUG_ANY,
			"connection_init(%d, %s): set nonblocking failed\n",
			s, c->c_peer_name.bv_val, 0 );
	}

	ldap_pvt_thread_mutex_lock( &conn_nextid_mutex );
	id = c->c_connid = conn_nextid++;
	ldap_pvt_thread_mutex_unlock( &conn_nextid_mutex );

	ldap_pvt_thread_mutex_lock( &connections_mutex );
	c->c_conn_state = SLAP_C_INACTIVE;
	c->c_struct_state = SLAP_C_USED;
	ldap_pvt_thread_mutex_unlock( &connections_mutex );
	c->c_close_reason = "?";			/* should never be needed */

	c->c_ssf = c->c_transport_ssf = ssf;
	c->c_tls_ssf = 0;

#ifdef HAVE_TLS
	if ( flags & CONN_IS_TLS ) {
		c->c_is_tls = 1;
		c->c_needs_tls_accept = 1;
	} else {
		c->c_is_tls = 0;
		c->c_needs_tls_accept = 0;
	}
#endif

	slap_sasl_open( c, 0 );
	slap_sasl_external( c, ssf, authid );

	slapd_add_internal( s, 1 );

	backend_connection_init(c);
	ldap_pvt_thread_mutex_unlock( &c->c_mutex );

	if ( !(flags & CONN_IS_UDP ))
		Statslog( LDAP_DEBUG_STATS,
			"conn=%ld fd=%ld ACCEPT from %s (%s)\n",
			id, (long) s, peername, listener->sl_name.bv_val, 0 );

	return c;
}

void connection2anonymous( Connection *c )
{
	assert( connections != NULL );
	assert( c != NULL );

	{
		ber_len_t max = sockbuf_max_incoming;
		ber_sockbuf_ctrl( c->c_sb, LBER_SB_OPT_SET_MAX_INCOMING, &max );
	}

	if ( !BER_BVISNULL( &c->c_authmech ) ) {
		ch_free(c->c_authmech.bv_val);
	}
	BER_BVZERO( &c->c_authmech );

	if ( !BER_BVISNULL( &c->c_dn ) ) {
		ch_free(c->c_dn.bv_val);
	}
	BER_BVZERO( &c->c_dn );

	if ( !BER_BVISNULL( &c->c_ndn ) ) {
		ch_free(c->c_ndn.bv_val);
	}
	BER_BVZERO( &c->c_ndn );

	if ( !BER_BVISNULL( &c->c_sasl_authz_dn ) ) {
		ber_memfree_x( c->c_sasl_authz_dn.bv_val, NULL );
	}
	BER_BVZERO( &c->c_sasl_authz_dn );

	c->c_authz_backend = NULL;
}

static void
connection_destroy( Connection *c )
{
	unsigned long	connid;
	const char		*close_reason;
	Sockbuf			*sb;
	ber_socket_t	sd;

	assert( connections != NULL );
	assert( c != NULL );
	assert( c->c_struct_state != SLAP_C_UNUSED );
	assert( c->c_conn_state != SLAP_C_INVALID );
	assert( LDAP_STAILQ_EMPTY(&c->c_ops) );
	assert( LDAP_STAILQ_EMPTY(&c->c_pending_ops) );
#ifdef LDAP_X_TXN
	assert( c->c_txn == CONN_TXN_INACTIVE );
	assert( c->c_txn_backend == NULL );
	assert( LDAP_STAILQ_EMPTY(&c->c_txn_ops) );
#endif
	assert( c->c_writewaiter == 0);
	assert( c->c_writers == 0);

	/* only for stats (print -1 as "%lu" may give unexpected results ;) */
	connid = c->c_connid;
	close_reason = c->c_close_reason;

	ldap_pvt_thread_mutex_lock( &connections_mutex );
	c->c_struct_state = SLAP_C_PENDING;
	ldap_pvt_thread_mutex_unlock( &connections_mutex );

	backend_connection_destroy(c);

	c->c_protocol = 0;
	c->c_connid = -1;

	c->c_activitytime = c->c_starttime = 0;

	connection2anonymous( c );
	c->c_listener = NULL;

	if(c->c_peer_domain.bv_val != NULL) {
		free(c->c_peer_domain.bv_val);
	}
	BER_BVZERO( &c->c_peer_domain );
	if(c->c_peer_name.bv_val != NULL) {
		free(c->c_peer_name.bv_val);
	}
	BER_BVZERO( &c->c_peer_name );

	c->c_sasl_bind_in_progress = 0;
	if(c->c_sasl_bind_mech.bv_val != NULL) {
		free(c->c_sasl_bind_mech.bv_val);
	}
	BER_BVZERO( &c->c_sasl_bind_mech );

	slap_sasl_close( c );

	if ( c->c_currentber != NULL ) {
		ber_free( c->c_currentber, 1 );
		c->c_currentber = NULL;
	}


#ifdef LDAP_SLAPI
	/* call destructors, then constructors; avoids unnecessary allocation */
	if ( slapi_plugins_used ) {
		slapi_int_clear_object_extensions( SLAPI_X_EXT_CONNECTION, c );
	}
#endif

	sd = c->c_sd;
	c->c_sd = AC_SOCKET_INVALID;
	c->c_conn_state = SLAP_C_INVALID;
	c->c_struct_state = SLAP_C_UNUSED;
	c->c_close_reason = "?";			/* should never be needed */

	sb = c->c_sb;
	c->c_sb = ber_sockbuf_alloc( );
	{
		ber_len_t max = sockbuf_max_incoming;
		ber_sockbuf_ctrl( c->c_sb, LBER_SB_OPT_SET_MAX_INCOMING, &max );
	}

	/* c must be fully reset by this point; when we call slapd_remove
	 * it may get immediately reused by a new connection.
	 */
	if ( sd != AC_SOCKET_INVALID ) {
		slapd_remove( sd, sb, 1, 0, 0 );

		if ( close_reason == NULL ) {
			Statslog( LDAP_DEBUG_STATS, "conn=%lu fd=%ld closed\n",
				connid, (long) sd, 0, 0, 0 );
		} else {
			Statslog( LDAP_DEBUG_STATS, "conn=%lu fd=%ld closed (%s)\n",
				connid, (long) sd, close_reason, 0, 0 );
		}
	}
}

int connection_valid( Connection *c )
{
	/* c_mutex must be locked by caller */

	assert( c != NULL );

	return c->c_struct_state == SLAP_C_USED &&
		c->c_conn_state >= SLAP_C_ACTIVE &&
		c->c_conn_state <= SLAP_C_CLIENT;
}

static void connection_abandon( Connection *c )
{
	/* c_mutex must be locked by caller */

	Operation *o, *next, op = {0};
	Opheader ohdr = {0};

	op.o_hdr = &ohdr;
	op.o_conn = c;
	op.o_connid = c->c_connid;
	op.o_tag = LDAP_REQ_ABANDON;

	for ( o = LDAP_STAILQ_FIRST( &c->c_ops ); o; o=next ) {
		SlapReply rs = {REP_RESULT};

		next = LDAP_STAILQ_NEXT( o, o_next );
		op.orn_msgid = o->o_msgid;
		o->o_abandon = 1;
		op.o_bd = frontendDB;
		frontendDB->be_abandon( &op, &rs );
	}

#ifdef LDAP_X_TXN
	/* remove operations in pending transaction */
	while ( (o = LDAP_STAILQ_FIRST( &c->c_txn_ops )) != NULL) {
		LDAP_STAILQ_REMOVE_HEAD( &c->c_txn_ops, o_next );
		LDAP_STAILQ_NEXT(o, o_next) = NULL;
		slap_op_free( o, NULL );
	}

	/* clear transaction */
	c->c_txn_backend = NULL;
	c->c_txn = CONN_TXN_INACTIVE;
#endif

	/* remove pending operations */
	while ( (o = LDAP_STAILQ_FIRST( &c->c_pending_ops )) != NULL) {
		LDAP_STAILQ_REMOVE_HEAD( &c->c_pending_ops, o_next );
		LDAP_STAILQ_NEXT(o, o_next) = NULL;
		slap_op_free( o, NULL );
	}
}

static void
connection_wake_writers( Connection *c )
{
	/* wake write blocked operations */
	ldap_pvt_thread_mutex_lock( &c->c_write1_mutex );
	if ( c->c_writers > 0 ) {
		c->c_writers = -c->c_writers;
		ldap_pvt_thread_cond_broadcast( &c->c_write1_cv );
		ldap_pvt_thread_mutex_unlock( &c->c_write1_mutex );
		if ( c->c_writewaiter ) {
			ldap_pvt_thread_mutex_lock( &c->c_write2_mutex );
			ldap_pvt_thread_cond_signal( &c->c_write2_cv );
			slapd_clr_write( c->c_sd, 1 );
			ldap_pvt_thread_mutex_unlock( &c->c_write2_mutex );
		}
		ldap_pvt_thread_mutex_lock( &c->c_write1_mutex );
		while ( c->c_writers ) {
			ldap_pvt_thread_cond_wait( &c->c_write1_cv, &c->c_write1_mutex );
		}
		ldap_pvt_thread_mutex_unlock( &c->c_write1_mutex );
	} else {
		ldap_pvt_thread_mutex_unlock( &c->c_write1_mutex );
		slapd_clr_write( c->c_sd, 1 );
	}
}

void connection_closing( Connection *c, const char *why )
{
	assert( connections != NULL );
	assert( c != NULL );

	if ( c->c_struct_state != SLAP_C_USED ) return;

	assert( c->c_conn_state != SLAP_C_INVALID );

	/* c_mutex must be locked by caller */

	if( c->c_conn_state != SLAP_C_CLOSING ) {
		Debug( LDAP_DEBUG_CONNS,
			"connection_closing: readying conn=%lu sd=%d for close\n",
			c->c_connid, c->c_sd, 0 );
		/* update state to closing */
		c->c_conn_state = SLAP_C_CLOSING;
		c->c_close_reason = why;

		/* don't listen on this port anymore */
		slapd_clr_read( c->c_sd, 0 );

		/* abandon active operations */
		connection_abandon( c );

		/* wake write blocked operations */
		connection_wake_writers( c );

	} else if( why == NULL && c->c_close_reason == conn_lost_str ) {
		/* Client closed connection after doing Unbind. */
		c->c_close_reason = NULL;
	}
}

static void
connection_close( Connection *c )
{
	assert( connections != NULL );
	assert( c != NULL );

	if ( c->c_struct_state != SLAP_C_USED ) return;

	assert( c->c_conn_state == SLAP_C_CLOSING );

	/* NOTE: c_mutex should be locked by caller */

	if ( !LDAP_STAILQ_EMPTY(&c->c_ops) ||
		!LDAP_STAILQ_EMPTY(&c->c_pending_ops) )
	{
		Debug( LDAP_DEBUG_CONNS,
			"connection_close: deferring conn=%lu sd=%d\n",
			c->c_connid, c->c_sd, 0 );
		return;
	}

	Debug( LDAP_DEBUG_TRACE, "connection_close: conn=%lu sd=%d\n",
		c->c_connid, c->c_sd, 0 );

	connection_destroy( c );
}

unsigned long connections_nextid(void)
{
	unsigned long id;
	assert( connections != NULL );

	ldap_pvt_thread_mutex_lock( &conn_nextid_mutex );

	id = conn_nextid;

	ldap_pvt_thread_mutex_unlock( &conn_nextid_mutex );

	return id;
}

/*
 * Loop through the connections:
 *
 *	for (c = connection_first(&i); c; c = connection_next(c, &i)) ...;
 *	connection_done(c);
 *
 * 'i' is the cursor, initialized by connection_first().
 * 'c_mutex' is locked in the returned connection.  The functions must
 * be passed the previous return value so they can unlock it again.
 */

Connection* connection_first( ber_socket_t *index )
{
	assert( connections != NULL );
	assert( index != NULL );

	ldap_pvt_thread_mutex_lock( &connections_mutex );
	for( *index = 0; *index < dtblsize; (*index)++) {
		if( connections[*index].c_struct_state != SLAP_C_UNINITIALIZED ) {
			break;
		}
	}
	ldap_pvt_thread_mutex_unlock( &connections_mutex );

	return connection_next(NULL, index);
}

/* Next connection in loop, see connection_first() */
Connection* connection_next( Connection *c, ber_socket_t *index )
{
	assert( connections != NULL );
	assert( index != NULL );
	assert( *index <= dtblsize );

	if( c != NULL ) ldap_pvt_thread_mutex_unlock( &c->c_mutex );

	c = NULL;

	ldap_pvt_thread_mutex_lock( &connections_mutex );
	for(; *index < dtblsize; (*index)++) {
		int c_struct;
		if( connections[*index].c_struct_state == SLAP_C_UNINITIALIZED ) {
			/* FIXME: accessing c_conn_state without locking c_mutex */
			assert( connections[*index].c_conn_state == SLAP_C_INVALID );
			continue;
		}

		if( connections[*index].c_struct_state == SLAP_C_USED ) {
			c = &connections[(*index)++];
			if ( ldap_pvt_thread_mutex_trylock( &c->c_mutex )) {
				/* avoid deadlock */
				ldap_pvt_thread_mutex_unlock( &connections_mutex );
				ldap_pvt_thread_mutex_lock( &c->c_mutex );
				ldap_pvt_thread_mutex_lock( &connections_mutex );
				if ( c->c_struct_state != SLAP_C_USED ) {
					ldap_pvt_thread_mutex_unlock( &c->c_mutex );
					c = NULL;
					continue;
				}
			}
			assert( c->c_conn_state != SLAP_C_INVALID );
			break;
		}

		c_struct = connections[*index].c_struct_state;
		if ( c_struct == SLAP_C_PENDING )
			continue;
		assert( c_struct == SLAP_C_UNUSED );
		/* FIXME: accessing c_conn_state without locking c_mutex */
		assert( connections[*index].c_conn_state == SLAP_C_INVALID );
	}

	ldap_pvt_thread_mutex_unlock( &connections_mutex );
	return c;
}

/* End connection loop, see connection_first() */
void connection_done( Connection *c )
{
	assert( connections != NULL );

	if( c != NULL ) ldap_pvt_thread_mutex_unlock( &c->c_mutex );
}

/*
 * connection_activity - handle the request operation op on connection
 * conn.  This routine figures out what kind of operation it is and
 * calls the appropriate stub to handle it.
 */

#ifdef SLAPD_MONITOR
/* FIXME: returns 0 in case of failure */
#define INCR_OP_INITIATED(index) \
	do { \
		ldap_pvt_thread_mutex_lock( &op->o_counters->sc_mutex ); \
		ldap_pvt_mp_add_ulong(op->o_counters->sc_ops_initiated_[(index)], 1); \
		ldap_pvt_thread_mutex_unlock( &op->o_counters->sc_mutex ); \
	} while (0)
#define INCR_OP_COMPLETED(index) \
	do { \
		ldap_pvt_thread_mutex_lock( &op->o_counters->sc_mutex ); \
		ldap_pvt_mp_add_ulong(op->o_counters->sc_ops_completed, 1); \
		ldap_pvt_mp_add_ulong(op->o_counters->sc_ops_completed_[(index)], 1); \
		ldap_pvt_thread_mutex_unlock( &op->o_counters->sc_mutex ); \
	} while (0)
#else /* !SLAPD_MONITOR */
#define INCR_OP_INITIATED(index) do { } while (0)
#define INCR_OP_COMPLETED(index) \
	do { \
		ldap_pvt_thread_mutex_lock( &op->o_counters->sc_mutex ); \
		ldap_pvt_mp_add_ulong(op->o_counters->sc_ops_completed, 1); \
		ldap_pvt_thread_mutex_unlock( &op->o_counters->sc_mutex ); \
	} while (0)
#endif /* !SLAPD_MONITOR */

/*
 * NOTE: keep in sync with enum in slapd.h
 */
static BI_op_func *opfun[] = {
	do_bind,
	do_unbind,
	do_search,
	do_compare,
	do_modify,
	do_modrdn,
	do_add,
	do_delete,
	do_abandon,
	do_extended,