GameNetworkingSockets/examples/example_chat.cpp

//====== Copyright Valve Corporation, All rights reserved. ====================
//
// Example client/server chat application using SteamNetworkingSockets

#include <assert.h>
#include <stdio.h>
#include <stdarg.h>
#include <string.h>
#include <algorithm>
#include <string>
#include <random>
#include <chrono>
#include <thread>
#include <mutex>
#include <queue>
#include <map>
#include <cctype>

#include <steam/steamnetworkingsockets.h>
#include <steam/isteamnetworkingutils.h>
#ifndef STEAMNETWORKINGSOCKETS_OPENSOURCE
#include <steam/steam_api.h>
#endif

#ifdef WIN32
	#include <windows.h> // Ug, for NukeProcess -- see below
#else
	#include <unistd.h>
	#include <signal.h>
#endif

/////////////////////////////////////////////////////////////////////////////
//
// Common stuff
//
/////////////////////////////////////////////////////////////////////////////

bool g_bQuit = false;

SteamNetworkingMicroseconds g_logTimeZero;

// We do this because I won't want to figure out how to cleanly shut
// down the thread that is reading from stdin.
static void NukeProcess( int rc )
{
	#ifdef WIN32
		ExitProcess( rc );
	#else
		kill( getpid(), SIGKILL );
	#endif
}

static void DebugOutput( ESteamNetworkingSocketsDebugOutputType eType, const char *pszMsg )
{
	SteamNetworkingMicroseconds time = SteamNetworkingUtils()->GetLocalTimestamp() - g_logTimeZero;
	printf( "%10.6f %s\n", time*1e-6, pszMsg );
	fflush(stdout);
	if ( eType == k_ESteamNetworkingSocketsDebugOutputType_Bug )
	{
		fflush(stdout);
		fflush(stderr);
		NukeProcess(1);
	}
}

static void FatalError( const char *fmt, ... )
{
	char text[ 2048 ];
	va_list ap;
	va_start( ap, fmt );
	vsprintf( text, fmt, ap );
	va_end(ap);
	char *nl = strchr( text, '\0' ) - 1;
	if ( nl >= text && *nl == '\n' )
		*nl = '\0';
	DebugOutput( k_ESteamNetworkingSocketsDebugOutputType_Bug, text );
}

static void Printf( const char *fmt, ... )
{
	char text[ 2048 ];
	va_list ap;
	va_start( ap, fmt );
	vsprintf( text, fmt, ap );
	va_end(ap);
	char *nl = strchr( text, '\0' ) - 1;
	if ( nl >= text && *nl == '\n' )
		*nl = '\0';
	DebugOutput( k_ESteamNetworkingSocketsDebugOutputType_Msg, text );
}

static void InitSteamDatagramConnectionSockets()
{
	#ifdef STEAMNETWORKINGSOCKETS_OPENSOURCE
		SteamDatagramErrMsg errMsg;
		if ( !GameNetworkingSockets_Init( nullptr, errMsg ) )
			FatalError( "GameNetworkingSockets_Init failed.  %s", errMsg );
	#else
		SteamDatagramClient_SetAppID( 570 ); // Just set something, doesn't matter what
		//SteamDatagramClient_SetUniverse( k_EUniverseDev );

		SteamDatagramErrMsg errMsg;
		if ( !SteamDatagramClient_Init( true, errMsg ) )
			FatalError( "SteamDatagramClient_Init failed.  %s", errMsg );

		// Disable authentication when running with Steam, for this
		// example, since we're not a real app.
		//
		// Authentication is disabled automatically in the open-source
		// version since we don't have a trusted third party to issue
		// certs.
		SteamNetworkingUtils()->SetGlobalConfigValueInt32( k_ESteamNetworkingConfig_IP_AllowWithoutAuth, 1 );
	#endif

	g_logTimeZero = SteamNetworkingUtils()->GetLocalTimestamp();

	SteamNetworkingUtils()->SetDebugOutputFunction( k_ESteamNetworkingSocketsDebugOutputType_Msg, DebugOutput );
}

static void ShutdownSteamDatagramConnectionSockets()
{
	// Give connections time to finish up.  This is an application layer protocol
	// here, it's not TCP.  Note that if you have an application and you need to be
	// more sure about cleanup, you won't be able to do this.  You will need to send
	// a message and then either wait for the peer to close the connection, or
	// you can pool the connection to see if any reliable data is pending.
	std::this_thread::sleep_for( std::chrono::milliseconds( 500 ) );

	#ifdef STEAMNETWORKINGSOCKETS_OPENSOURCE
		GameNetworkingSockets_Kill();
	#else
		SteamDatagramClient_Kill();
	#endif
}

/////////////////////////////////////////////////////////////////////////////
//
// Non-blocking console user input.  Sort of.
// Why is this so hard?
//
/////////////////////////////////////////////////////////////////////////////

std::mutex mutexUserInputQueue;
std::queue< std::string > queueUserInput;

std::thread *s_pThreadUserInput = nullptr;

void LocalUserInput_Init()
{
	s_pThreadUserInput = new std::thread( []()
	{
		while ( !g_bQuit )
		{
			char szLine[ 4000 ];
			if ( !fgets( szLine, sizeof(szLine), stdin ) )
			{
				// Well, you would hope that you could close the handle
				// from the other thread to trigger this.  Nope.
				if ( g_bQuit )
					return;
				g_bQuit = true;
				Printf( "Failed to read on stdin, quitting\n" );
				break;
			}

			mutexUserInputQueue.lock();
			queueUserInput.push( std::string( szLine ) );
			mutexUserInputQueue.unlock();
		}
	} );
}

void LocalUserInput_Kill()
{
// Does not work.  We won't clean up, we'll just nuke the process.
//	g_bQuit = true;
//	_close( fileno( stdin ) );
//
//	if ( s_pThreadUserInput )
//	{
//		s_pThreadUserInput->join();
//		delete s_pThreadUserInput;
//		s_pThreadUserInput = nullptr;
//	}
}

// You really gotta wonder what kind of pedantic garbage was
// going through the minds of people who designed std::string
// that they decided not to include trim.
// https://stackoverflow.com/questions/216823/whats-the-best-way-to-trim-stdstring

// trim from start (in place)
static inline void ltrim(std::string &s) {
    s.erase(s.begin(), std::find_if(s.begin(), s.end(), [](int ch) {
        return !std::isspace(ch);
    }));
}

// trim from end (in place)
static inline void rtrim(std::string &s) {
    s.erase(std::find_if(s.rbegin(), s.rend(), [](int ch) {
        return !std::isspace(ch);
    }).base(), s.end());
}


// Read the next line of input from stdin, if anything is available.
bool LocalUserInput_GetNext( std::string &result )
{
	bool got_input = false;
	mutexUserInputQueue.lock();
	while ( !queueUserInput.empty() && !got_input )
	{
		result = queueUserInput.front();
		queueUserInput.pop();
		ltrim(result);
		rtrim(result);
		got_input = !result.empty(); // ignore blank lines
	}
	mutexUserInputQueue.unlock();
	return got_input;
}

/////////////////////////////////////////////////////////////////////////////
//
// ChatServer
//
/////////////////////////////////////////////////////////////////////////////

class ChatServer : private ISteamNetworkingSocketsCallbacks
{
public:
	void Run( uint16 nPort )
	{
		// Select instance to use.  For now we'll always use the default.
		// But we could use SteamGameServerNetworkingSockets() on Steam.
		m_pInterface = SteamNetworkingSockets();

		// Start listening
		SteamNetworkingIPAddr serverLocalAddr;
		serverLocalAddr.Clear();
		serverLocalAddr.m_port = nPort;
		m_hListenSock = m_pInterface->CreateListenSocketIP( serverLocalAddr, 0, nullptr );
		if ( m_hListenSock == k_HSteamListenSocket_Invalid )
			FatalError( "Failed to listen on port %d", nPort );
		m_hPollGroup = m_pInterface->CreatePollGroup();
		if ( m_hPollGroup == k_HSteamNetPollGroup_Invalid )
			FatalError( "Failed to listen on port %d", nPort );
		Printf( "Server listening on port %d\n", nPort );

		while ( !g_bQuit )
		{
			PollIncomingMessages();
			PollConnectionStateChanges();
			PollLocalUserInput();
			std::this_thread::sleep_for( std::chrono::milliseconds( 10 ) );
		}

		// Close all the connections
		Printf( "Closing connections...\n" );
		for ( auto it: m_mapClients )
		{
			// Send them one more goodbye message.  Note that we also have the
			// connection close reason as a place to send final data.  However,
			// that's usually best left for more diagnostic/debug text not actual
			// protocol strings.
			SendStringToClient( it.first, "Server is shutting down.  Goodbye." );

			// Close the connection.  We use "linger mode" to ask SteamNetworkingSockets
			// to flush this out and close gracefully.
			m_pInterface->CloseConnection( it.first, 0, "Server Shutdown", true );
		}
		m_mapClients.clear();

		m_pInterface->CloseListenSocket( m_hListenSock );
		m_hListenSock = k_HSteamListenSocket_Invalid;

		m_pInterface->DestroyPollGroup( m_hPollGroup );
		m_hPollGroup = k_HSteamNetPollGroup_Invalid;
	}
private:

	HSteamListenSocket m_hListenSock;
	HSteamNetPollGroup m_hPollGroup;
	ISteamNetworkingSockets *m_pInterface;

	struct Client_t
	{
		std::string m_sNick;
	};

	std::map< HSteamNetConnection, Client_t > m_mapClients;

	void SendStringToClient( HSteamNetConnection conn, const char *str )
	{
		m_pInterface->SendMessageToConnection( conn, str, (uint32)strlen(str), k_nSteamNetworkingSend_Reliable, nullptr );
	}

	void SendStringToAllClients( const char *str, HSteamNetConnection except = k_HSteamNetConnection_Invalid )
	{
		for ( auto &c: m_mapClients )
		{
			if ( c.first != except )
				SendStringToClient( c.first, str );
		}
	}

	void PollIncomingMessages()
	{
		char temp[ 1024 ];

		while ( !g_bQuit )
		{
			ISteamNetworkingMessage *pIncomingMsg = nullptr;
			int numMsgs = m_pInterface->ReceiveMessagesOnPollGroup( m_hPollGroup, &pIncomingMsg, 1 );
			if ( numMsgs == 0 )
				break;
			if ( numMsgs < 0 )
				FatalError( "Error checking for messages" );
			assert( numMsgs == 1 && pIncomingMsg );
			auto itClient = m_mapClients.find( pIncomingMsg->m_conn );
			assert( itClient != m_mapClients.end() );

			// '\0'-terminate it to make it easier to parse
			std::string sCmd;
			sCmd.assign( (const char *)pIncomingMsg->m_pData, pIncomingMsg->m_cbSize );
			const char *cmd = sCmd.c_str();

			// We don't need this anymore.
			pIncomingMsg->Release();

			// Check for known commands.  None of this example code is secure or robust.
			// Don't write a real server like this, please.

			if ( strncmp( cmd, "/nick", 5 ) == 0 )
			{
				const char *nick = cmd+5;
				while ( isspace(*nick) )
					++nick;

				// Let everybody else know they changed their name
				sprintf( temp, "%s shall henceforth be known as %s", itClient->second.m_sNick.c_str(), nick );
				SendStringToAllClients( temp, itClient->first );

				// Respond to client
				sprintf( temp, "Ye shall henceforth be known as %s", nick );
				SendStringToClient( itClient->first, temp );

				// Actually change their name
				SetClientNick( itClient->first, nick );
				continue;
			}

			// Assume it's just a ordinary chat message, dispatch to everybody else
			sprintf( temp, "%s: %s", itClient->second.m_sNick.c_str(), cmd );
			SendStringToAllClients( temp, itClient->first );
		}
	}

	void PollConnectionStateChanges()
	{
		m_pInterface->RunCallbacks( this );
	}

	void PollLocalUserInput()
	{
		std::string cmd;
		while ( !g_bQuit && LocalUserInput_GetNext( cmd ))
		{
			if ( strcmp( cmd.c_str(), "/quit" ) == 0 )
			{
				g_bQuit = true;
				Printf( "Shutting down server" );
				break;
			}

			// That's the only command we support
			Printf( "The server only knows one command: '/quit'" );
		}
	}

	void SetClientNick( HSteamNetConnection hConn, const char *nick )
	{

		// Remember their nick
		m_mapClients[hConn].m_sNick = nick;

		// Set the connection name, too, which is useful for debugging
		m_pInterface->SetConnectionName( hConn, nick );
	}

	virtual void OnSteamNetConnectionStatusChanged( SteamNetConnectionStatusChangedCallback_t *pInfo ) override
	{
		char temp[1024];

		// What's the state of the connection?
		switch ( pInfo->m_info.m_eState )
		{
			case k_ESteamNetworkingConnectionState_None:
				// NOTE: We will get callbacks here when we destroy connections.  You can ignore these.
				break;

			case k_ESteamNetworkingConnectionState_ClosedByPeer:
			case k_ESteamNetworkingConnectionState_ProblemDetectedLocally:
			{
				// Ignore if they were not previously connected.  (If they disconnected
				// before we accepted the connection.)
				if ( pInfo->m_eOldState == k_ESteamNetworkingConnectionState_Connected )
				{

					// Locate the client.  Note that it should have been found, because this
					// is the only codepath where we remove clients (except on shutdown),
					// and connection change callbacks are dispatched in queue order.
					auto itClient = m_mapClients.find( pInfo->m_hConn );
					assert( itClient != m_mapClients.end() );

					// Select appropriate log messages
					const char *pszDebugLogAction;
					if ( pInfo->m_info.m_eState == k_ESteamNetworkingConnectionState_ProblemDetectedLocally )
					{
						pszDebugLogAction = "problem detected locally";
						sprintf( temp, "Alas, %s hath fallen into shadow.  (%s)", itClient->second.m_sNick.c_str(), pInfo->m_info.m_szEndDebug );
					}
					else
					{
						// Note that here we could check the reason code to see if
						// it was a "usual" connection or an "unusual" one.
						pszDebugLogAction = "closed by peer";
						sprintf( temp, "%s hath departed", itClient->second.m_sNick.c_str() );
					}

					// Spew something to our own log.  Note that because we put their nick
					// as the connection description, it will show up, along with their
					// transport-specific data (e.g. their IP address)
					Printf( "Connection %s %s, reason %d: %s\n",
						pInfo->m_info.m_szConnectionDescription,
						pszDebugLogAction,
						pInfo->m_info.m_eEndReason,
						pInfo->m_info.m_szEndDebug
					);

					m_mapClients.erase( itClient );

					// Send a message so everybody else knows what happened
					SendStringToAllClients( temp );
				}
				else
				{
					assert( pInfo->m_eOldState == k_ESteamNetworkingConnectionState_Connecting );
				}

				// Clean up the connection.  This is important!
				// The connection is "closed" in the network sense, but
				// it has not been destroyed.  We must close it on our end, too
				// to finish up.  The reason information do not matter in this case,
				// and we cannot linger because it's already closed on the other end,
				// so we just pass 0's.
				m_pInterface->CloseConnection( pInfo->m_hConn, 0, nullptr, false );
				break;
			}

			case k_ESteamNetworkingConnectionState_Connecting:
			{
				// This must be a new connection
				assert( m_mapClients.find( pInfo->m_hConn ) == m_mapClients.end() );

				Printf( "Connection request from %s", pInfo->m_info.m_szConnectionDescription );

				// A client is attempting to connect
				// Try to accept the connection.
				if ( m_pInterface->AcceptConnection( pInfo->m_hConn ) != k_EResultOK )
				{
					// This could fail.  If the remote host tried to connect, but then
					// disconnected, the connection may already be half closed.  Just
					// destroy whatever we have on our side.
					m_pInterface->CloseConnection( pInfo->m_hConn, 0, nullptr, false );
					Printf( "Can't accept connection.  (It was already closed?)" );
					break;
				}

				// Assign the poll group
				if ( !m_pInterface->SetConnectionPollGroup( pInfo->m_hConn, m_hPollGroup ) )
				{
					m_pInterface->CloseConnection( pInfo->m_hConn, 0, nullptr, false );
					Printf( "Failed to set poll group?" );
					break;
				}

				// Generate a random nick.  A random temporary nick
				// is really dumb and not how you would write a real chat server.
				// You would want them to have some sort of signon message,
				// and you would keep their client in a state of limbo (connected,
				// but not logged on) until them.  I'm trying to keep this example
				// code really simple.
				char nick[ 64 ];
				sprintf( nick, "BraveWarrior%d", 10000 + ( rand() % 100000 ) );

				// Send them a welcome message
				sprintf( temp, "Welcome, stranger.  Thou art known to us for now as '%s'; upon thine command '/nick' we shall know thee otherwise.", nick ); 
				SendStringToClient( pInfo->m_hConn, temp ); 

				// Also send them a list of everybody who is already connected
				if ( m_mapClients.empty() )
				{
					SendStringToClient( pInfo->m_hConn, "Thou art utterly alone." ); 
				}
				else
				{
					sprintf( temp, "%d companions greet you:", (int)m_mapClients.size() ); 
					for ( auto &c: m_mapClients )
						SendStringToClient( pInfo->m_hConn, c.second.m_sNick.c_str() ); 
				}

				// Let everybody else know who they are for now
				sprintf( temp, "Hark!  A stranger hath joined this merry host.  For now we shall call them '%s'", nick ); 
				SendStringToAllClients( temp, pInfo->m_hConn ); 

				// Add them to the client list, using std::map wacky syntax
				m_mapClients[ pInfo->m_hConn ];
				SetClientNick( pInfo->m_hConn, nick );
				break;
			}

			case k_ESteamNetworkingConnectionState_Connected:
				// We will get a callback immediately after accepting the connection.
				// Since we are the server, we can ignore this, it's not news to us.
				break;

			default:
				// Silences -Wswitch
				break;
		}
	}
};

/////////////////////////////////////////////////////////////////////////////
//
// ChatClient
//
/////////////////////////////////////////////////////////////////////////////

class ChatClient : private ISteamNetworkingSocketsCallbacks
{
public:
	void Run( const SteamNetworkingIPAddr &serverAddr )
	{
		// Select instance to use.  For now we'll always use the default.
		m_pInterface = SteamNetworkingSockets();

		// Start connecting
		char szAddr[ SteamNetworkingIPAddr::k_cchMaxString ];
		serverAddr.ToString( szAddr, sizeof(szAddr), true );
		Printf( "Connecting to chat server at %s", szAddr );
		m_hConnection = m_pInterface->ConnectByIPAddress( serverAddr, 0, nullptr );
		if ( m_hConnection == k_HSteamNetConnection_Invalid )
			FatalError( "Failed to create connection" );

		while ( !g_bQuit )
		{
			PollIncomingMessages();
			PollConnectionStateChanges();
			PollLocalUserInput();
			std::this_thread::sleep_for( std::chrono::milliseconds( 10 ) );
		}
	}
private:

	HSteamNetConnection m_hConnection;
	ISteamNetworkingSockets *m_pInterface;

	void PollIncomingMessages()
	{
		while ( !g_bQuit )
		{
			ISteamNetworkingMessage *pIncomingMsg = nullptr;
			int numMsgs = m_pInterface->ReceiveMessagesOnConnection( m_hConnection, &pIncomingMsg, 1 );
			if ( numMsgs == 0 )
				break;
			if ( numMsgs < 0 )
				FatalError( "Error checking for messages" );

			// Just echo anything we get from the server
			fwrite( pIncomingMsg->m_pData, 1, pIncomingMsg->m_cbSize, stdout );
			fputc( '\n', stdout );

			// We don't need this anymore.
			pIncomingMsg->Release();
		}
	}

	void PollConnectionStateChanges()
	{
		m_pInterface->RunCallbacks( this );
	}

	void PollLocalUserInput()
	{
		std::string cmd;
		while ( !g_bQuit && LocalUserInput_GetNext( cmd ))
		{

			// Check for known commands
			if ( strcmp( cmd.c_str(), "/quit" ) == 0 )
			{
				g_bQuit = true;
				Printf( "Disconnecting from chat server" );

				// Close the connection gracefully.
				// We use linger mode to ask for any remaining reliable data
				// to be flushed out.  But remember this is an application
				// protocol on UDP.  See ShutdownSteamDatagramConnectionSockets
				m_pInterface->CloseConnection( m_hConnection, 0, "Goodbye", true );
				break;
			}

			// Anything else, just send it to the server and let them parse it
			m_pInterface->SendMessageToConnection( m_hConnection, cmd.c_str(), (uint32)cmd.length(), k_nSteamNetworkingSend_Reliable, nullptr );
		}
	}

	virtual void OnSteamNetConnectionStatusChanged( SteamNetConnectionStatusChangedCallback_t *pInfo ) override
	{
		assert( pInfo->m_hConn == m_hConnection || m_hConnection == k_HSteamNetConnection_Invalid );

		// What's the state of the connection?
		switch ( pInfo->m_info.m_eState )
		{
			case k_ESteamNetworkingConnectionState_None:
				// NOTE: We will get callbacks here when we destroy connections.  You can ignore these.
				break;

			case k_ESteamNetworkingConnectionState_ClosedByPeer:
			case k_ESteamNetworkingConnectionState_ProblemDetectedLocally:
			{
				g_bQuit = true;

				// Print an appropriate message
				if ( pInfo->m_eOldState == k_ESteamNetworkingConnectionState_Connecting )
				{
					// Note: we could distinguish between a timeout, a rejected connection,
					// or some other transport problem.
					Printf( "We sought the remote host, yet our efforts were met with defeat.  (%s)", pInfo->m_info.m_szEndDebug );
				}
				else if ( pInfo->m_info.m_eState == k_ESteamNetworkingConnectionState_ProblemDetectedLocally )
				{
					Printf( "Alas, troubles beset us; we have lost contact with the host.  (%s)", pInfo->m_info.m_szEndDebug );
				}
				else
				{
					// NOTE: We could check the reason code for a normal disconnection
					Printf( "The host hath bidden us farewell.  (%s)", pInfo->m_info.m_szEndDebug );
				}

				// Clean up the connection.  This is important!
				// The connection is "closed" in the network sense, but
				// it has not been destroyed.  We must close it on our end, too
				// to finish up.  The reason information do not matter in this case,
				// and we cannot linger because it's already closed on the other end,
				// so we just pass 0's.
				m_pInterface->CloseConnection( pInfo->m_hConn, 0, nullptr, false );
				m_hConnection = k_HSteamNetConnection_Invalid;
				break;
			}

			case k_ESteamNetworkingConnectionState_Connecting:
				// We will get this callback when we start connecting.
				// We can ignore this.
				break;

			case k_ESteamNetworkingConnectionState_Connected:
				Printf( "Connected to server OK" );
				break;

			default:
				// Silences -Wswitch
				break;
		}
	}
};

const uint16 DEFAULT_SERVER_PORT = 27020;

void PrintUsageAndExit( int rc = 1 )
{
	fflush(stderr);
	printf(
R"usage(Usage:
    example_chat client SERVER_ADDR
    example_chat server [--port PORT]
)usage"
	);
	fflush(stdout);
	exit(rc);
}

int main( int argc, const char *argv[] )
{
	bool bServer = false;
	bool bClient = false;
	int nPort = DEFAULT_SERVER_PORT;
	SteamNetworkingIPAddr addrServer; addrServer.Clear();

	for ( int i = 1 ; i < argc ; ++i )
	{
		if ( !bClient && !bServer )
		{
			if ( !strcmp( argv[i], "client" ) )
			{
				bClient = true;
				continue;
			}
			if ( !strcmp( argv[i], "server" ) )
			{
				bServer = true;
				continue;
			}
		}
		if ( !strcmp( argv[i], "--port" ) )
		{
			++i;
			if ( i >= argc )
				PrintUsageAndExit();
			nPort = atoi( argv[i] );
			if ( nPort <= 0 || nPort > 65535 )
				FatalError( "Invalid port %d", nPort );
			continue;
		}

		// Anything else, must be server address to connect to
		if ( bClient && addrServer.IsIPv6AllZeros() )
		{
			if ( !addrServer.ParseString( argv[i] ) )
				FatalError( "Invalid server address '%s'", argv[i] );
			if ( addrServer.m_port == 0 )
				addrServer.m_port = DEFAULT_SERVER_PORT;
			continue;
		}

		PrintUsageAndExit();
	}

	if ( bClient == bServer || ( bClient && addrServer.IsIPv6AllZeros() ) )
		PrintUsageAndExit();

	// Create client and server sockets
	InitSteamDatagramConnectionSockets();
	LocalUserInput_Init();

	if ( bClient )
	{
		ChatClient client;
		client.Run( addrServer );
	}
	else
	{
		ChatServer server;
		server.Run( (uint16)nPort );
	}

	ShutdownSteamDatagramConnectionSockets();

	// Ug, why is there no simple solution for portable, non-blocking console user input?
	// Just nuke the process
	//LocalUserInput_Kill();
	NukeProcess(0);
}