Query game port on server create (#63)

* Query game port on server create

Seems to work okay with real game servers

* Only warn on wrong line endings instead of error

package-lock.json

@@ -8,6 +8,7 @@
 			"license": "MIT",
 			"dependencies": {
 				"bad-words": "^3.0.4",
+				"bit-buffer": "^0.2.5",
 				"dotenv": "^10.0.0",
 				"fastify": "^3.24.0",
 				"fastify-cors": "^6.0.2",
@@ -371,6 +372,11 @@
 				"node": ">=8"
 			}
 		},
+		"node_modules/bit-buffer": {
+			"version": "0.2.5",
+			"resolved": "https://registry.npmjs.org/bit-buffer/-/bit-buffer-0.2.5.tgz",
+			"integrity": "sha512-x1yGnmXvFg6e3DiyRztElbcn1bsCTFSoM/ncAzY62uE0JdTl5xlKJd0ooqLYoPbhdsnpehSIQrdIvclcZJYwiA=="
+		},
 		"node_modules/block-stream": {
 			"version": "0.0.9",
 			"resolved": "https://registry.npmjs.org/block-stream/-/block-stream-0.0.9.tgz",
@@ -4111,6 +4117,11 @@
 			"integrity": "sha512-jDctJ/IVQbZoJykoeHbhXpOlNBqGNcwXJKJog42E5HDPUwQTSdjCHdihjj0DlnheQ7blbT6dHOafNAiS8ooQKA==",
 			"dev": true
 		},
+		"bit-buffer": {
+			"version": "0.2.5",
+			"resolved": "https://registry.npmjs.org/bit-buffer/-/bit-buffer-0.2.5.tgz",
+			"integrity": "sha512-x1yGnmXvFg6e3DiyRztElbcn1bsCTFSoM/ncAzY62uE0JdTl5xlKJd0ooqLYoPbhdsnpehSIQrdIvclcZJYwiA=="
+		},
 		"block-stream": {
 			"version": "0.0.9",
 			"resolved": "https://registry.npmjs.org/block-stream/-/block-stream-0.0.9.tgz",

package.json

@@ -16,6 +16,7 @@
 	},
 	"dependencies": {
 		"bad-words": "^3.0.4",
+		"bit-buffer": "^0.2.5",
 		"dotenv": "^10.0.0",
 		"fastify": "^3.24.0",
 		"fastify-cors": "^6.0.2",

server/gameserver.js

@@ -4,6 +4,7 @@ const { GameServer, GetGameServers, AddGameServer, RemoveGameServer, GetGhostSer
 const asyncHttp = require( path.join( __dirname, "../shared/asynchttp.js" ) )
 const pjson = require( path.join( __dirname, "../shared/pjson.js" ) )
 const { minimumVersion } = require( path.join( __dirname, "../shared/version.js" ) )
+const { QueryServerPort } = require( path.join( __dirname, "../shared/udp_query.js" ) )
 const Filter = require( "bad-words" )
 let filter = new Filter()
 
@@ -35,6 +36,9 @@ async function TryVerifyServer( request )
 	if ( !authServerResponse || authServerResponse.toString() != VERIFY_STRING )
 		return 1
 
+	let gamePortDoesRespond = await QueryServerPort( request.ip, request.query.port )
+	if( !gamePortDoesRespond ) return 1
+
 	return 0
 }
 

shared/a2s_challenge_query.js

@@ -0,0 +1,192 @@
+///// Credit to R5Reloaded for the following code /////
+
+/// Netmessages ///
+const BitBuffer = require( "bit-buffer" )
+
+const R5Messages = {
+	a2s_getchallenge: function( uid )
+	{
+		let buf = Buffer.alloc( 1600 )
+		let stream = new BitBuffer.BitStream( buf )
+
+		stream.writeInt32( -1 )
+		stream.writeUint8( "H".charCodeAt( 0 ) )
+		stream.writeASCIIString( "connect" )
+
+		stream.writeUint32( Number( uid & 0xffffffffn ) )
+		stream.writeUint32( Number( uid >> 32n ) )
+
+		stream.writeUint8( 2 )
+
+		const ret = stream.buffer.slice( stream.buffer.byteOffset, stream.byteIndex ) // ???
+		return ret
+	}
+}
+/// Netmessages END ///
+
+/// Crypto ///
+const crypto = require( "crypto" )
+
+class rSrcNetCrypto
+{
+	constructor( key )
+	{
+		this.key = Buffer.from( key, "base64" )
+		this.aad = Buffer.from(
+			"\x01\x02\x03\x04\x05\x06\x07\x08\t\n\x0b\x0c\r\x0e\x0f\x10",
+			"ascii"
+		)
+		//this.iv = Buffer.from("aaaaaaaaaaaaaaaaaaaaaaaa", "hex")
+	}
+
+	encrypt( data, bytes = -1 )
+	{
+		this.iv = crypto.randomBytes( 12 )
+
+		let cipher = crypto.createCipheriv( "aes-128-gcm", this.key, this.iv )
+		cipher.setAAD( this.aad )
+
+		let encrypted = Buffer.concat( [
+			cipher.update( data.slice( 0, bytes > 0 ? bytes : data.length ) ),
+			cipher.final(),
+		] )
+
+		let tag = cipher.getAuthTag()
+
+		const ret = Buffer.concat( [this.iv, tag, encrypted] )
+
+		return ret
+	}
+
+	decrypt( packet_data )
+	{
+		let iv = packet_data.slice( 0, 12 )
+		let tag = packet_data.slice( 12, 16 )
+		let data = packet_data.slice( 12 + 16, packet_data.length )
+
+		let decipher = crypto.createDecipheriv( "aes-128-gcm", this.key, iv )
+
+		decipher.setAAD( this.aad )
+		decipher.setAuthTag( tag )
+
+		try
+		{
+			return Buffer.concat( [decipher.update( data ), decipher.final()] )
+		}
+		catch ( e )
+		{
+			return Buffer.from( "000000000000000000000000" )
+		}
+	}
+}
+/// Crypto END ///
+
+/// Networking ///
+const dgram = require( "dgram" )
+const { EventEmitter } = require( "stream" )
+
+class rSrcNetClient
+{
+	constructor( owner )
+	{
+		this._owner = owner
+	}
+
+	onMessage( msg, rinfo )
+	{
+		if ( rinfo.address != this.ip || rinfo.port != this.port )
+		{
+			//console.log("Mismatch?", rinfo)
+			return
+		}
+
+		const decryptedData = this._owner.crypto.decrypt( msg )
+		this._owner.emit( "data", decryptedData )
+	}
+
+	send( data, bytes = -1 )
+	{
+		const enc = this._owner.crypto.encrypt( data, bytes )
+		this.socket.send( enc, this.port, this.ip )
+	}
+
+	connect( ip, port )
+	{
+		this.ip = ip
+		this.port = port
+		this.socket = dgram.createSocket( {
+			type: "udp4",
+			reuseAddr: false,
+		} )
+
+		const data = R5Messages.a2s_getchallenge( this._owner.connectionSettings.uid )
+		const enc = this._owner.crypto.encrypt( data )
+
+		this.socket.bind(
+			{
+				port: 0,
+				exclusive: true,
+				//exclusive: false,
+			},
+			() =>
+			{
+				this.bindPort = this.socket.address().port
+				this.socket.send( enc, this.port, this.ip )
+			}
+		)
+
+		this.socket.on( "message", this.onMessage.bind( this ) )
+	}
+
+	close()
+	{
+		this.socket.close()
+	}
+}
+/// Networking END ///
+
+/// Main client class ///
+class rSrcClient extends EventEmitter
+{
+	constructor( constgs )
+	{
+		super()
+
+		this.connectionSettings = constgs
+
+		this.crypto = new rSrcNetCrypto( this.connectionSettings.encryptionKey )
+		this.net = new rSrcNetClient( this )
+
+		this.on( "data", this.onData.bind( this ) )
+	}
+
+	connect()
+	{
+		this.net.connect( this.connectionSettings.ip, this.connectionSettings.port )
+	}
+
+	onData( data )
+	{
+		if ( data.readInt32LE() != -1 )
+			return // not connectionless
+
+		if ( data.readUint8( 4 ) != 73 )
+			return // not challenge response
+
+		if ( data.readBigInt64LE( 9 ) != this.connectionSettings.uid )
+			return // challenge not for this uid
+
+		const challenge = data.readInt32LE( 5 )
+		this.emit( "challenge", challenge )
+
+		this.net.close()
+	}
+
+	close()
+	{
+		this.net.close()
+	}
+}
+/// Main client class END ///
+
+module.exports = rSrcClient

shared/udp_query.js

@@ -0,0 +1,33 @@
+const rSrcClient = require( "./a2s_challenge_query" )
+
+const encryptionKey = "WDNWLmJYQ2ZlM0VoTid3Yg==" // standard r2 encryption key
+
+function QueryServerPort( ip, port )
+{
+	return new Promise( resolve =>
+	{
+		const client = new rSrcClient( {
+			encryptionKey,
+			ip,
+			port,
+			uid: 1000000001337n,
+		} )
+
+		let queryTimeout = setTimeout( () =>
+		{
+			resolve( false ) // return false on timeout reached
+		}, 1000 )
+
+		client.on( "challenge", async () =>
+		{
+			clearTimeout( queryTimeout )
+			resolve( true ) // return true on challenge response
+		} )
+
+		client.connect() // attempt to connect to the game server
+	} )
+}
+
+module.exports = {
+	QueryServerPort
+}