connection.c

/* $OpenLDAP$ */
/* This work is part of OpenLDAP Software <http://www.openldap.org/>.
 *
 * Copyright 1998-2005 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_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 = 0;

/* structure state (protected by connections_mutex) */
#define SLAP_C_UNINITIALIZED	0x00	/* MUST BE ZERO (0) */
#define SLAP_C_UNUSED			0x01
#define SLAP_C_USED				0x02

/* connection state (protected by c_mutex ) */
#define SLAP_C_INVALID			0x00	/* MUST BE ZERO (0) */
#define SLAP_C_INACTIVE			0x01	/* zero threads */
#define SLAP_C_ACTIVE			0x02	/* one or more threads */
#define SLAP_C_BINDING			0x03	/* binding */
#define SLAP_C_CLOSING			0x04	/* closing */
#define SLAP_C_CLIENT			0x05	/* outbound client conn */

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

	return "?";
}

static Connection* connection_get( ber_socket_t s );

static int connection_input( Connection *c );
static void connection_close( Connection *c );

static int connection_op_activate( 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_write_mutex );
			ldap_pvt_thread_cond_destroy( &connections[i].c_write_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;

	ldap_pvt_thread_mutex_lock( &connections_mutex );

	for ( i = 0; i < dtblsize; i++ ) {
		if( connections[i].c_struct_state != SLAP_C_USED ) {
			continue;
		}
		/* 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 );
			continue;
		}

		ldap_pvt_thread_mutex_lock( &connections[i].c_mutex );

		/* connections_mutex and c_mutex are locked */
		connection_closing( &connections[i] );
		connection_close( &connections[i] );

		ldap_pvt_thread_mutex_unlock( &connections[i].c_mutex );
	}

	ldap_pvt_thread_mutex_unlock( &connections_mutex );

	return 0;
}

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

	for( c = connection_first( &connindex );
		c != NULL;
		c = connection_next( c, &connindex ) )
	{
		/* Don't timeout a slow-running request or a persistent
		 * outbound connection */
		if( c->c_n_ops_executing ||
			c->c_conn_state == SLAP_C_CLIENT ) continue;

		if( difftime( c->c_activitytime+global_idletimeout, now) < 0 ) {
			/* close it */
			connection_closing( c );
			connection_close( c );
			i++;
		}
	}
	connection_done( c );

	return i;
}

static Connection* connection_get( ber_socket_t s )
{
	/* connections_mutex should be locked by caller */

	Connection *c;

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

	assert( connections != NULL );

	if(s == AC_SOCKET_INVALID) {
		return NULL;
	}

#ifndef HAVE_WINSOCK
	c = &connections[s];

	assert( c->c_struct_state != SLAP_C_UNINITIALIZED );

#else
	c = NULL;
	{
		ber_socket_t i, sd;

		for(i=0; i<dtblsize; i++) {
			if( connections[i].c_struct_state == SLAP_C_UNINITIALIZED ) {
				assert( connections[i].c_conn_state == SLAP_C_INVALID );
				assert( connections[i].c_sb == 0 );
				break;
			}

			ber_sockbuf_ctrl( connections[i].c_sb,
				LBER_SB_OPT_GET_FD, &sd );

			if( connections[i].c_struct_state == SLAP_C_UNUSED ) {
				assert( connections[i].c_conn_state == SLAP_C_INVALID );
				assert( sd == AC_SOCKET_INVALID );
				continue;
			}

			/* state can actually change from used -> unused by resched,
			 * so don't assert details here.
			 */

			if( sd == s ) {
				c = &connections[i];
				break;
			}
		}
	}
#endif

	if( c != NULL ) {
		ber_socket_t	sd;

		ldap_pvt_thread_mutex_lock( &c->c_mutex );

		ber_sockbuf_ctrl( c->c_sb, LBER_SB_OPT_GET_FD, &sd );
		if( c->c_struct_state != SLAP_C_USED ) {
			/* connection must have been closed due to resched */

			assert( c->c_conn_state == SLAP_C_INVALID );
			assert( sd == AC_SOCKET_INVALID );

			Debug( LDAP_DEBUG_TRACE,
				"connection_get(%d): connection not used\n",
				s, 0, 0 );

			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( 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 );
}

long connection_init(
	ber_socket_t s,
	Listener *listener,
	const char* dnsname,
	const char* peername,
	int flags,
	slap_ssf_t ssf,
	struct berval *authid )
{
	unsigned long id;
	Connection *c;

	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 -1;
	}

	assert( s >= 0 );
#ifndef HAVE_WINSOCK
	assert( s < dtblsize );
#endif

	ldap_pvt_thread_mutex_lock( &connections_mutex );

#ifndef HAVE_WINSOCK
	c = &connections[s];

#else
	{
		ber_socket_t i;
		c = NULL;

		for( i=0; i < dtblsize; i++) {
			ber_socket_t	sd;

			if( connections[i].c_struct_state == SLAP_C_UNINITIALIZED ) {
				assert( connections[i].c_sb == 0 );
				c = &connections[i];
				break;
			}

			sd = AC_SOCKET_INVALID;
			if (connections[i].c_sb != NULL) {
				ber_sockbuf_ctrl( connections[i].c_sb,
					LBER_SB_OPT_GET_FD, &sd );
			}

			if( connections[i].c_struct_state == SLAP_C_UNUSED ) {
				assert( sd == AC_SOCKET_INVALID );
				c = &connections[i];
				break;
			}

			if( connections[i].c_conn_state == SLAP_C_CLIENT ) {
				continue;
			}

			assert( connections[i].c_struct_state == SLAP_C_USED );
			assert( connections[i].c_conn_state != SLAP_C_INVALID );
			assert( sd != AC_SOCKET_INVALID );
		}

		if( c == NULL ) {
			Debug( LDAP_DEBUG_ANY,
				"connection_init(%d): connection table full "
				"(%d/%d)\n", s, i, dtblsize);
			ldap_pvt_thread_mutex_unlock( &connections_mutex );
			return -1;
		}
	}
#endif

	assert( c != NULL );

	if( c->c_struct_state == SLAP_C_UNINITIALIZED ) {
		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;
#ifdef LDAP_RES_INTERMEDIATE
		c->c_send_ldap_intermediate = slap_send_ldap_intermediate;
#endif

		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);

		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_write_mutex );
		ldap_pvt_thread_cond_init( &c->c_write_cv );

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

		c->c_struct_state = SLAP_C_UNUSED;
	}

	ldap_pvt_thread_mutex_lock( &c->c_mutex );

	assert( c->c_struct_state == SLAP_C_UNUSED );
	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) );
	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);

	c->c_listener = listener;

	if ( flags == CONN_IS_CLIENT ) {
		c->c_conn_state = SLAP_C_CLIENT;
		c->c_struct_state = SLAP_C_USED;
		ber_sockbuf_ctrl( c->c_sb, LBER_SB_OPT_SET_FD, &s );
		ldap_pvt_thread_mutex_unlock( &c->c_mutex );
		ldap_pvt_thread_mutex_unlock( &connections_mutex );

		return 0;
	}

	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 *)&s );
		ber_sockbuf_add_io( c->c_sb, &ber_sockbuf_io_readahead,
			LBER_SBIOD_LEVEL_PROVIDER, NULL );
	} else
#endif
	{
#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 *)&s );
	}

#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 );

	c->c_conn_state = SLAP_C_INACTIVE;
	c->c_struct_state = SLAP_C_USED;

	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 );

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

	backend_connection_init(c);

	return id;
}

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 )
{
	/* note: connections_mutex should be locked by caller */
	ber_socket_t	sd;
	unsigned long	connid;

	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( c->c_writewaiter == 0);

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

	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;
	}

	ber_sockbuf_ctrl( c->c_sb, LBER_SB_OPT_GET_FD, &sd );
	if ( sd != AC_SOCKET_INVALID ) {
		slapd_remove( sd, 1, 0 );

		Statslog( LDAP_DEBUG_STATS,
			"conn=%lu fd=%ld closed\n",
			connid, (long) sd, 0, 0, 0 );
	}

	ber_sockbuf_free( 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->c_conn_state = SLAP_C_INVALID;
	c->c_struct_state = SLAP_C_UNUSED;

#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
}

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

	int state;
	assert( c != NULL );
	assert( c->c_struct_state == SLAP_C_USED );

	state = c->c_conn_state;

	assert( state != SLAP_C_INVALID );

	return state == SLAP_C_CLOSING;
}

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

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

	/* 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 );
	}
}

void connection_closing( Connection *c )
{
	assert( connections != NULL );
	assert( c != NULL );
	assert( c->c_struct_state == SLAP_C_USED );
	assert( c->c_conn_state != SLAP_C_INVALID );

	/* c_mutex must be locked by caller */

	if( c->c_conn_state != SLAP_C_CLOSING ) {
		ber_socket_t	sd;

		ber_sockbuf_ctrl( c->c_sb, LBER_SB_OPT_GET_FD, &sd );
		Debug( LDAP_DEBUG_TRACE,
			"connection_closing: readying conn=%lu sd=%d for close\n",
			c->c_connid, sd, 0 );
		/* update state to closing */
		c->c_conn_state = SLAP_C_CLOSING;

		/* don't listen on this port anymore */
		slapd_clr_read( sd, 1 );

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

		/* wake write blocked operations */
		slapd_clr_write( sd, 1 );
		if ( c->c_writewaiter ) {
			ldap_pvt_thread_cond_signal( &c->c_write_cv );
			ldap_pvt_thread_mutex_unlock( &c->c_mutex );
			ldap_pvt_thread_yield();
			ldap_pvt_thread_mutex_lock( &c->c_mutex );
		}
	}
}

static void connection_close( Connection *c )
{
	ber_socket_t	sd;

	assert( connections != NULL );
	assert( c != NULL );
	assert( c->c_struct_state == SLAP_C_USED );
	assert( c->c_conn_state == SLAP_C_CLOSING );

	/* note: connections_mutex and c_mutex should be locked by caller */

	ber_sockbuf_ctrl( c->c_sb, LBER_SB_OPT_GET_FD, &sd );
	if( !LDAP_STAILQ_EMPTY(&c->c_ops) ) {
		Debug( LDAP_DEBUG_TRACE,
			"connection_close: deferring conn=%lu sd=%d\n",
			c->c_connid, sd, 0 );
		return;
	}

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

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

	ldap_pvt_thread_mutex_lock( &connections_mutex );

	id = conn_nextid;

	ldap_pvt_thread_mutex_unlock( &connections_mutex );

	return id;
}

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

	ldap_pvt_thread_mutex_lock( &connections_mutex );

	*index = 0;

	return connection_next(NULL, index);
}

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;

	for(; *index < dtblsize; (*index)++) {
		if( connections[*index].c_struct_state == SLAP_C_UNINITIALIZED ) {
			assert( connections[*index].c_conn_state == SLAP_C_INVALID );
#ifndef HAVE_WINSOCK
			continue;
#else
			break;
#endif
		}

		if( connections[*index].c_struct_state == SLAP_C_USED ) {
			assert( connections[*index].c_conn_state != SLAP_C_INVALID );
			c = &connections[(*index)++];
			break;
		}

		assert( connections[*index].c_struct_state == SLAP_C_UNUSED );
		assert( connections[*index].c_conn_state == SLAP_C_INVALID );
	}

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

	return c;
}

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

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

	ldap_pvt_thread_mutex_unlock( &connections_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( &slap_counters.sc_ops_mutex ); \
		ldap_pvt_mp_add_ulong(slap_counters.sc_ops_initiated_[(index)], 1); \
		ldap_pvt_thread_mutex_unlock( &slap_counters.sc_ops_mutex ); \
	} while (0)
#define INCR_OP_COMPLETED(index) \