FreeRDP/libfreerdp/core/nego.c
2012-08-14 17:09:01 -04:00

950 lines
21 KiB
C

/**
* FreeRDP: A Remote Desktop Protocol Client
* RDP Protocol Security Negotiation
*
* Copyright 2011 Marc-Andre Moreau <marcandre.moreau@gmail.com>
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <stdio.h>
#include <string.h>
#include <freerdp/constants.h>
#include <freerdp/utils/memory.h>
#include "tpkt.h"
#include "nego.h"
#include "transport.h"
static const char* const NEGO_STATE_STRINGS[] =
{
"NEGO_STATE_INITIAL",
"NEGO_STATE_NLA",
"NEGO_STATE_TLS",
"NEGO_STATE_RDP",
"NEGO_STATE_FAIL",
"NEGO_STATE_FINAL"
};
static const char PROTOCOL_SECURITY_STRINGS[3][4] =
{
"RDP",
"TLS",
"NLA"
};
boolean nego_security_connect(rdpNego* nego);
/**
* Negotiate protocol security and connect.
* @param nego
* @return
*/
boolean nego_connect(rdpNego* nego)
{
if (nego->state == NEGO_STATE_INITIAL)
{
if (nego->enabled_protocols[PROTOCOL_NLA] > 0)
nego->state = NEGO_STATE_NLA;
else if (nego->enabled_protocols[PROTOCOL_TLS] > 0)
nego->state = NEGO_STATE_TLS;
else if (nego->enabled_protocols[PROTOCOL_RDP] > 0)
nego->state = NEGO_STATE_RDP;
else
{
DEBUG_NEGO("No security protocol is enabled");
nego->state = NEGO_STATE_FAIL;
}
if (!nego->security_layer_negotiation_enabled)
{
DEBUG_NEGO("Security Layer Negotiation is disabled");
/* attempt only the highest enabled protocol (see nego_attempt_*) */
nego->enabled_protocols[PROTOCOL_NLA] = 0;
nego->enabled_protocols[PROTOCOL_TLS] = 0;
nego->enabled_protocols[PROTOCOL_RDP] = 0;
if(nego->state == NEGO_STATE_NLA)
{
nego->enabled_protocols[PROTOCOL_NLA] = 1;
nego->selected_protocol = PROTOCOL_NLA;
}
else if (nego->state == NEGO_STATE_TLS)
{
nego->enabled_protocols[PROTOCOL_TLS] = 1;
nego->selected_protocol = PROTOCOL_TLS;
}
else if (nego->state == NEGO_STATE_RDP)
{
nego->enabled_protocols[PROTOCOL_RDP] = 1;
nego->selected_protocol = PROTOCOL_RDP;
}
}
if(!nego_send_preconnection_pdu(nego))
{
DEBUG_NEGO("Failed to send preconnection information");
nego->state = NEGO_STATE_FINAL;
return false;
}
}
do
{
DEBUG_NEGO("state: %s", NEGO_STATE_STRINGS[nego->state]);
nego_send(nego);
if (nego->state == NEGO_STATE_FAIL)
{
DEBUG_NEGO("Protocol Security Negotiation Failure");
nego->state = NEGO_STATE_FINAL;
return false;
}
}
while (nego->state != NEGO_STATE_FINAL);
DEBUG_NEGO("Negotiated %s security", PROTOCOL_SECURITY_STRINGS[nego->selected_protocol]);
/* update settings with negotiated protocol security */
nego->transport->settings->requested_protocols = nego->requested_protocols;
nego->transport->settings->selected_protocol = nego->selected_protocol;
nego->transport->settings->negotiationFlags = nego->flags;
if(nego->selected_protocol == PROTOCOL_RDP)
{
nego->transport->settings->encryption = true;
nego->transport->settings->encryption_method = ENCRYPTION_METHOD_40BIT | ENCRYPTION_METHOD_128BIT | ENCRYPTION_METHOD_FIPS;
nego->transport->settings->encryption_level = ENCRYPTION_LEVEL_CLIENT_COMPATIBLE;
}
/* finally connect security layer (if not already done) */
if(!nego_security_connect(nego))
{
DEBUG_NEGO("Failed to connect with %s security", PROTOCOL_SECURITY_STRINGS[nego->selected_protocol]);
return false;
}
return true;
}
/* connect to selected security layer */
boolean nego_security_connect(rdpNego* nego)
{
if(!nego->tcp_connected)
{
nego->security_connected = false;
}
else if (!nego->security_connected)
{
if (nego->selected_protocol == PROTOCOL_NLA)
{
DEBUG_NEGO("nego_security_connect with PROTOCOL_NLA");
nego->security_connected = transport_connect_nla(nego->transport);
}
else if (nego->selected_protocol == PROTOCOL_TLS )
{
DEBUG_NEGO("nego_security_connect with PROTOCOL_TLS");
nego->security_connected = transport_connect_tls(nego->transport);
}
else if (nego->selected_protocol == PROTOCOL_RDP)
{
DEBUG_NEGO("nego_security_connect with PROTOCOL_RDP");
nego->security_connected = transport_connect_rdp(nego->transport);
}
else
{
DEBUG_NEGO("cannot connect security layer because no protocol has been selected yet.");
}
}
return nego->security_connected;
}
/**
* Connect TCP layer.
* @param nego
* @return
*/
boolean nego_tcp_connect(rdpNego* nego)
{
if (!nego->tcp_connected)
nego->tcp_connected = transport_connect(nego->transport, nego->hostname, nego->port);
return nego->tcp_connected;
}
/**
* Connect TCP layer. For direct approach, connect security layer as well.
* @param nego
* @return
*/
boolean nego_transport_connect(rdpNego* nego)
{
nego_tcp_connect(nego);
if (nego->tcp_connected && !nego->security_layer_negotiation_enabled)
return nego_security_connect(nego);
return nego->tcp_connected;
}
/**
* Disconnect TCP layer.
* @param nego
* @return
*/
int nego_transport_disconnect(rdpNego* nego)
{
if (nego->tcp_connected)
transport_disconnect(nego->transport);
nego->tcp_connected = 0;
nego->security_connected = 0;
return 1;
}
/**
* Send preconnection information if enabled.
* @param nego
* @return
*/
boolean nego_send_preconnection_pdu(rdpNego* nego)
{
STREAM* s;
uint32 cbSize;
UNICONV* uniconv;
uint16 cchPCB_times2 = 0;
char* wszPCB = NULL;
if (!nego->send_preconnection_pdu)
return true;
DEBUG_NEGO("Sending preconnection PDU");
if (!nego_tcp_connect(nego))
return false;
/* it's easier to always send the version 2 PDU, and it's just 2 bytes overhead */
cbSize = PRECONNECTION_PDU_V2_MIN_SIZE;
if (nego->preconnection_blob)
{
size_t size;
uniconv = freerdp_uniconv_new();
wszPCB = freerdp_uniconv_out(uniconv, nego->preconnection_blob, &size);
cchPCB_times2 = (uint16) size;
freerdp_uniconv_free(uniconv);
cchPCB_times2 += 2; /* zero-termination */
cbSize += cchPCB_times2;
}
s = transport_send_stream_init(nego->transport, cbSize);
stream_write_uint32(s, cbSize); /* cbSize */
stream_write_uint32(s, 0); /* Flags */
stream_write_uint32(s, PRECONNECTION_PDU_V2); /* Version */
stream_write_uint32(s, nego->preconnection_id); /* Id */
stream_write_uint16(s, cchPCB_times2 / 2); /* cchPCB */
if (wszPCB)
{
stream_write(s, wszPCB, cchPCB_times2); /* wszPCB */
xfree(wszPCB);
}
if (transport_write(nego->transport, s) < 0)
return false;
return true;
}
/**
* Attempt negotiating NLA + TLS security.
* @param nego
*/
void nego_attempt_nla(rdpNego* nego)
{
nego->requested_protocols = PROTOCOL_NLA | PROTOCOL_TLS;
DEBUG_NEGO("Attempting NLA security");
if (!nego_transport_connect(nego))
{
nego->state = NEGO_STATE_FAIL;
return;
}
if (!nego_send_negotiation_request(nego))
{
nego->state = NEGO_STATE_FAIL;
return;
}
if (!nego_recv_response(nego))
{
nego->state = NEGO_STATE_FAIL;
return;
}
DEBUG_NEGO("state: %s", NEGO_STATE_STRINGS[nego->state]);
if (nego->state != NEGO_STATE_FINAL)
{
nego_transport_disconnect(nego);
if (nego->enabled_protocols[PROTOCOL_TLS] > 0)
nego->state = NEGO_STATE_TLS;
else if (nego->enabled_protocols[PROTOCOL_RDP] > 0)
nego->state = NEGO_STATE_RDP;
else
nego->state = NEGO_STATE_FAIL;
}
}
/**
* Attempt negotiating TLS security.
* @param nego
*/
void nego_attempt_tls(rdpNego* nego)
{
nego->requested_protocols = PROTOCOL_TLS;
DEBUG_NEGO("Attempting TLS security");
if (!nego_transport_connect(nego))
{
nego->state = NEGO_STATE_FAIL;
return;
}
if (!nego_send_negotiation_request(nego))
{
nego->state = NEGO_STATE_FAIL;
return;
}
if (!nego_recv_response(nego))
{
nego->state = NEGO_STATE_FAIL;
return;
}
if (nego->state != NEGO_STATE_FINAL)
{
nego_transport_disconnect(nego);
if (nego->enabled_protocols[PROTOCOL_RDP] > 0)
nego->state = NEGO_STATE_RDP;
else
nego->state = NEGO_STATE_FAIL;
}
}
/**
* Attempt negotiating standard RDP security.
* @param nego
*/
void nego_attempt_rdp(rdpNego* nego)
{
nego->requested_protocols = PROTOCOL_RDP;
DEBUG_NEGO("Attempting RDP security");
if (!nego_transport_connect(nego))
{
nego->state = NEGO_STATE_FAIL;
return;
}
if (!nego_send_negotiation_request(nego))
{
nego->state = NEGO_STATE_FAIL;
return;
}
if (!nego_recv_response(nego))
{
nego->state = NEGO_STATE_FAIL;
return;
}
}
/**
* Wait to receive a negotiation response
* @param nego
*/
boolean nego_recv_response(rdpNego* nego)
{
STREAM* s = transport_recv_stream_init(nego->transport, 1024);
if (transport_read(nego->transport, s) < 0)
return false;
return nego_recv(nego->transport, s, nego);
}
/**
* Receive protocol security negotiation message.\n
* @msdn{cc240501}
* @param transport transport
* @param s stream
* @param extra nego pointer
*/
boolean nego_recv(rdpTransport* transport, STREAM* s, void* extra)
{
uint8 li;
uint8 type;
rdpNego* nego = (rdpNego*) extra;
if (tpkt_read_header(s) == 0)
return false;
li = tpdu_read_connection_confirm(s);
if (li > 6)
{
/* rdpNegData (optional) */
stream_read_uint8(s, type); /* Type */
switch (type)
{
case TYPE_RDP_NEG_RSP:
nego_process_negotiation_response(nego, s);
DEBUG_NEGO("selected_protocol: %d", nego->selected_protocol);
/* enhanced security selected ? */
if (nego->selected_protocol)
{
if ((nego->selected_protocol == PROTOCOL_NLA) &&
(!nego->enabled_protocols[PROTOCOL_NLA]))
{
nego->state = NEGO_STATE_FAIL;
}
if ((nego->selected_protocol == PROTOCOL_TLS) &&
(!nego->enabled_protocols[PROTOCOL_TLS]))
{
nego->state = NEGO_STATE_FAIL;
}
}
else if (!nego->enabled_protocols[PROTOCOL_RDP])
{
nego->state = NEGO_STATE_FAIL;
}
break;
case TYPE_RDP_NEG_FAILURE:
nego_process_negotiation_failure(nego, s);
break;
}
}
else
{
DEBUG_NEGO("no rdpNegData");
if (!nego->enabled_protocols[PROTOCOL_RDP])
nego->state = NEGO_STATE_FAIL;
else
nego->state = NEGO_STATE_FINAL;
}
return true;
}
/**
* Read protocol security negotiation request message.\n
* @param nego
* @param s stream
*/
boolean nego_read_request(rdpNego* nego, STREAM* s)
{
uint8 li;
uint8 c;
uint8 type;
tpkt_read_header(s);
li = tpdu_read_connection_request(s);
if (li != stream_get_left(s) + 6)
{
printf("Incorrect TPDU length indicator.\n");
return false;
}
if (stream_get_left(s) > 8)
{
/* Optional routingToken or cookie, ending with CR+LF */
while (stream_get_left(s) > 0)
{
stream_read_uint8(s, c);
if (c != '\x0D')
continue;
stream_peek_uint8(s, c);
if (c != '\x0A')
continue;
stream_seek_uint8(s);
break;
}
}
if (stream_get_left(s) >= 8)
{
/* rdpNegData (optional) */
stream_read_uint8(s, type); /* Type */
if (type != TYPE_RDP_NEG_REQ)
{
printf("Incorrect negotiation request type %d\n", type);
return false;
}
nego_process_negotiation_request(nego, s);
}
return true;
}
/**
* Send protocol security negotiation message.
* @param nego
*/
void nego_send(rdpNego* nego)
{
if (nego->state == NEGO_STATE_NLA)
nego_attempt_nla(nego);
else if (nego->state == NEGO_STATE_TLS)
nego_attempt_tls(nego);
else if (nego->state == NEGO_STATE_RDP)
nego_attempt_rdp(nego);
else
DEBUG_NEGO("invalid negotiation state for sending");
}
/**
* Send RDP Negotiation Request (RDP_NEG_REQ).\n
* @msdn{cc240500}\n
* @msdn{cc240470}
* @param nego
*/
boolean nego_send_negotiation_request(rdpNego* nego)
{
STREAM* s;
int length;
uint8 *bm, *em;
s = transport_send_stream_init(nego->transport, 256);
length = TPDU_CONNECTION_REQUEST_LENGTH;
stream_get_mark(s, bm);
stream_seek(s, length);
if (nego->routing_token != NULL)
{
stream_write(s, nego->routing_token->data, nego->routing_token->length);
length += nego->routing_token->length;
}
else if (nego->cookie != NULL)
{
int cookie_length = strlen(nego->cookie);
stream_write(s, "Cookie: mstshash=", 17);
stream_write(s, (uint8*) nego->cookie, cookie_length);
stream_write_uint8(s, 0x0D); /* CR */
stream_write_uint8(s, 0x0A); /* LF */
length += cookie_length + 19;
}
DEBUG_NEGO("requested_protocols: %d", nego->requested_protocols);
if (nego->requested_protocols > PROTOCOL_RDP)
{
/* RDP_NEG_DATA must be present for TLS and NLA */
stream_write_uint8(s, TYPE_RDP_NEG_REQ);
stream_write_uint8(s, 0); /* flags, must be set to zero */
stream_write_uint16(s, 8); /* RDP_NEG_DATA length (8) */
stream_write_uint32(s, nego->requested_protocols); /* requestedProtocols */
length += 8;
}
stream_get_mark(s, em);
stream_set_mark(s, bm);
tpkt_write_header(s, length);
tpdu_write_connection_request(s, length - 5);
stream_set_mark(s, em);
if (transport_write(nego->transport, s) < 0)
return false;
return true;
}
/**
* Process Negotiation Request from Connection Request message.
* @param nego
* @param s
*/
void nego_process_negotiation_request(rdpNego* nego, STREAM* s)
{
uint8 flags;
uint16 length;
DEBUG_NEGO("RDP_NEG_REQ");
stream_read_uint8(s, flags);
stream_read_uint16(s, length);
stream_read_uint32(s, nego->requested_protocols);
DEBUG_NEGO("requested_protocols: %d", nego->requested_protocols);
nego->state = NEGO_STATE_FINAL;
}
/**
* Process Negotiation Response from Connection Confirm message.
* @param nego
* @param s
*/
void nego_process_negotiation_response(rdpNego* nego, STREAM* s)
{
uint16 length;
DEBUG_NEGO("RDP_NEG_RSP");
stream_read_uint8(s, nego->flags);
stream_read_uint16(s, length);
stream_read_uint32(s, nego->selected_protocol);
nego->state = NEGO_STATE_FINAL;
}
/**
* Process Negotiation Failure from Connection Confirm message.
* @param nego
* @param s
*/
void nego_process_negotiation_failure(rdpNego* nego, STREAM* s)
{
uint8 flags;
uint16 length;
uint32 failureCode;
DEBUG_NEGO("RDP_NEG_FAILURE");
stream_read_uint8(s, flags);
stream_read_uint16(s, length);
stream_read_uint32(s, failureCode);
switch (failureCode)
{
case SSL_REQUIRED_BY_SERVER:
DEBUG_NEGO("Error: SSL_REQUIRED_BY_SERVER");
break;
case SSL_NOT_ALLOWED_BY_SERVER:
DEBUG_NEGO("Error: SSL_NOT_ALLOWED_BY_SERVER");
break;
case SSL_CERT_NOT_ON_SERVER:
DEBUG_NEGO("Error: SSL_CERT_NOT_ON_SERVER");
break;
case INCONSISTENT_FLAGS:
DEBUG_NEGO("Error: INCONSISTENT_FLAGS");
break;
case HYBRID_REQUIRED_BY_SERVER:
DEBUG_NEGO("Error: HYBRID_REQUIRED_BY_SERVER");
break;
default:
DEBUG_NEGO("Error: Unknown protocol security error %d", failureCode);
break;
}
nego->state = NEGO_STATE_FAIL;
}
/**
* Send RDP Negotiation Response (RDP_NEG_RSP).\n
* @param nego
*/
boolean nego_send_negotiation_response(rdpNego* nego)
{
STREAM* s;
uint8* bm;
uint8* em;
int length;
boolean status;
rdpSettings* settings;
status = true;
settings = nego->transport->settings;
s = transport_send_stream_init(nego->transport, 256);
length = TPDU_CONNECTION_CONFIRM_LENGTH;
stream_get_mark(s, bm);
stream_seek(s, length);
if (nego->selected_protocol > PROTOCOL_RDP)
{
/* RDP_NEG_DATA must be present for TLS and NLA */
stream_write_uint8(s, TYPE_RDP_NEG_RSP);
stream_write_uint8(s, EXTENDED_CLIENT_DATA_SUPPORTED); /* flags */
stream_write_uint16(s, 8); /* RDP_NEG_DATA length (8) */
stream_write_uint32(s, nego->selected_protocol); /* selectedProtocol */
length += 8;
}
else if (!settings->rdp_security)
{
stream_write_uint8(s, TYPE_RDP_NEG_FAILURE);
stream_write_uint8(s, 0); /* flags */
stream_write_uint16(s, 8); /* RDP_NEG_DATA length (8) */
/*
* TODO: Check for other possibilities,
* like SSL_NOT_ALLOWED_BY_SERVER.
*/
printf("nego_send_negotiation_response: client supports only Standard RDP Security\n");
stream_write_uint32(s, SSL_REQUIRED_BY_SERVER);
length += 8;
status = false;
}
stream_get_mark(s, em);
stream_set_mark(s, bm);
tpkt_write_header(s, length);
tpdu_write_connection_confirm(s, length - 5);
stream_set_mark(s, em);
if (transport_write(nego->transport, s) < 0)
return false;
if (status)
{
/* update settings with negotiated protocol security */
settings->requested_protocols = nego->requested_protocols;
settings->selected_protocol = nego->selected_protocol;
if (settings->selected_protocol == PROTOCOL_RDP)
{
settings->tls_security = false;
settings->nla_security = false;
settings->rdp_security = true;
if (!settings->local)
{
settings->encryption = true;
settings->encryption_method = ENCRYPTION_METHOD_40BIT | ENCRYPTION_METHOD_128BIT | ENCRYPTION_METHOD_FIPS;
settings->encryption_level = ENCRYPTION_LEVEL_CLIENT_COMPATIBLE;
}
if (settings->encryption && settings->server_key == NULL && settings->rdp_key_file == NULL)
return false;
}
else if (settings->selected_protocol == PROTOCOL_TLS)
{
settings->tls_security = true;
settings->nla_security = false;
settings->rdp_security = false;
settings->encryption = false;
settings->encryption_method = ENCRYPTION_METHOD_NONE;
settings->encryption_level = ENCRYPTION_LEVEL_NONE;
}
else if (settings->selected_protocol == PROTOCOL_NLA)
{
settings->tls_security = true;
settings->nla_security = true;
settings->rdp_security = false;
settings->encryption = false;
settings->encryption_method = ENCRYPTION_METHOD_NONE;
settings->encryption_level = ENCRYPTION_LEVEL_NONE;
}
}
return status;
}
/**
* Initialize NEGO state machine.
* @param nego
*/
void nego_init(rdpNego* nego)
{
nego->state = NEGO_STATE_INITIAL;
nego->requested_protocols = PROTOCOL_RDP;
nego->transport->recv_callback = nego_recv;
nego->transport->recv_extra = (void*) nego;
nego->flags = 0;
}
/**
* Create a new NEGO state machine instance.
* @param transport
* @return
*/
rdpNego* nego_new(struct rdp_transport * transport)
{
rdpNego* nego = (rdpNego*) xzalloc(sizeof(rdpNego));
if (nego != NULL)
{
nego->transport = transport;
nego_init(nego);
}
return nego;
}
/**
* Free NEGO state machine.
* @param nego
*/
void nego_free(rdpNego* nego)
{
xfree(nego);
}
/**
* Set target hostname and port.
* @param nego
* @param hostname
* @param port
*/
void nego_set_target(rdpNego* nego, char* hostname, int port)
{
nego->hostname = hostname;
nego->port = port;
}
/**
* Enable security layer negotiation.
* @param nego pointer to the negotiation structure
* @param enable_rdp whether to enable security layer negotiation (true for enabled, false for disabled)
*/
void nego_set_negotiation_enabled(rdpNego* nego, boolean security_layer_negotiation_enabled)
{
DEBUG_NEGO("Enabling security layer negotiation: %s", security_layer_negotiation_enabled ? "true" : "false");
nego->security_layer_negotiation_enabled = security_layer_negotiation_enabled;
}
/**
* Enable RDP security protocol.
* @param nego pointer to the negotiation structure
* @param enable_rdp whether to enable normal RDP protocol (true for enabled, false for disabled)
*/
void nego_enable_rdp(rdpNego* nego, boolean enable_rdp)
{
DEBUG_NEGO("Enabling RDP security: %s", enable_rdp ? "true" : "false");
nego->enabled_protocols[PROTOCOL_RDP] = enable_rdp;
}
/**
* Enable TLS security protocol.
* @param nego pointer to the negotiation structure
* @param enable_tls whether to enable TLS + RDP protocol (true for enabled, false for disabled)
*/
void nego_enable_tls(rdpNego* nego, boolean enable_tls)
{
DEBUG_NEGO("Enabling TLS security: %s", enable_tls ? "true" : "false");
nego->enabled_protocols[PROTOCOL_TLS] = enable_tls;
}
/**
* Enable NLA security protocol.
* @param nego pointer to the negotiation structure
* @param enable_nla whether to enable network level authentication protocol (true for enabled, false for disabled)
*/
void nego_enable_nla(rdpNego* nego, boolean enable_nla)
{
DEBUG_NEGO("Enabling NLA security: %s", enable_nla ? "true" : "false");
nego->enabled_protocols[PROTOCOL_NLA] = enable_nla;
}
/**
* Set routing token.
* @param nego
* @param routing_token
*/
void nego_set_routing_token(rdpNego* nego, rdpBlob* routing_token)
{
nego->routing_token = routing_token;
}
/**
* Set cookie.
* @param nego
* @param cookie
*/
void nego_set_cookie(rdpNego* nego, char* cookie)
{
nego->cookie = cookie;
}
/**
* Enable / disable preconnection PDU.
* @param nego
* @param send_pcpdu
*/
void nego_set_send_preconnection_pdu(rdpNego* nego, boolean send_pcpdu)
{
nego->send_preconnection_pdu = send_pcpdu;
}
/**
* Set preconnection id.
* @param nego
* @param id
*/
void nego_set_preconnection_id(rdpNego* nego, uint32 id)
{
nego->preconnection_id = id;
}
/**
* Set preconnection blob.
* @param nego
* @param blob
*/
void nego_set_preconnection_blob(rdpNego* nego, char* blob)
{
nego->preconnection_blob = blob;
}