local SOCK5 proxy demo

localSOCK5ProxyDemo

net = require("net")
util = require("util")

AUTHENTICATION = 
  NOAUTH: 0x00
	GSSAOI: 0x01
	USERPASS: 0x02
	NONE:0xFF

ADDRTYPE = 
	IP_V4: 0x01
	DNS: 0x03
	IP_v6: 0x04
 
REQUEST_CMD = 
	CONNECT: 0x01
	BIND: 0x02
	UDP_ASSOCIATE: 0x03
 
REP_CMD_TYPE = 
	SUCCEEDED: 0x00
	GENERAL_SOCKS_SERVER_FAILURE: 0x01
	CONNECTION_NOT_ALLOWED_BY_RULESET: 0x02
	NETWORK_UNREACHABLE: 0x03
	HOST_UNREACHABLE: 0x04
	CONNECTION_REFUSED: 0x05
	TTL_EXPIRED: 0x06
	COMMAND_NOT_SUPPRTED: 0x07
	ADDRESS_TYPE_NOT_SUPPORTED: 0x08
	TO_XFF_UNASSIGNED: 0x09

SOCKS_VER = 0x05
inetNtoa = (buf)->
	buf[0] + "." + buf[1] + "." + buf[2] + "." + buf[3]

innetAton = (ipStr)->
	parts = ipStr.split(".")
	unless parts.length is 4
		null
	buf = new Buffer(4)
	i = 0;
	while i < 4
		buf[i] = +parts[i]
		i++
	buf

server = net.createServer (connection)->
	stage =0
	headerLength = 0
	remote = 0
	cachedPiess = []

	connection.on "data",(data)->
		if stage is 5
			connection.pause() unless remote.write(data)

		if stage is 0
			tempBuf = new Buffer(2)
			tempBuf.writeUInt8 SOCKS_VER,0
			tempBuf.writeUInt8 REP_CMD_TYPE.SUCCEEDED,1
			connection.write tempBuf
			stage = 1
			return

		if stage is 1
			try
				cmd = data[1]
				addrType = data[3]
				unless cmd is REQUEST_CMD.CONNECT
					util.log("unsupported cmd: " + cmd)
					reply = new Buffer(4)
					reply.writeUInt8 SOCKS_VER,0
					reply.writeUInt8 REP_CMD_TYPE.COMMAND_NOT_SUPPRTED ,1
					reply.writeUInt8 0x00,2
					reply.writeUInt8 0x00,3
					reply.writeUInt8 0x01,3
					connection.end reply
					return

				if addrType is ADDRTYPE.DNS
					addrLen = data[4]	
				else unless addrType is ADDRTYPE.IP_v4
					util.log("unsupported addrtype: " + addrtype)
					connection.end()
					return


				if addrType is ADDRTYPE.IP_v4
					remoteAddr = inetNtoa(data.slice(4,8))
					remotePort = data.readUInt16BE(8)
					headerLength = 10
				else
					# DNS
					remoteAddr = data.slice(5, 5 + addrLen).toString("binary")
					remotePort = data.readUInt16BE(5 + addrLen)
					headerLength = 5 + addrLen + 2
				buf = new Buffer(10)
				# REP_CMD_TYPE.SUCCEEDED
				buf.write("\u0005\u0000\u0000\u0001", 0, 4, "binary")
				buf.write("\u0000\u0000\u0000\u0000", 4, 4, "binary")
				buf.writeInt16BE(2222, 8)
				connection.write(buf)
				
				remote = net.connect(remotePort,remoteAddr,()->
						util.log("connecting " + remoteAddr + ":" + remotePort);
						i = 0
						while i < cachedPiess.length
							piece = cachedPiess[i]
							remote.write piece
							i++
						stage = 5
					)

				remote.on "data",(data)->
					remote.pause unless connection.write(data)

				remote.on "end",()->
					cachedPiess = null
					connection.end()

				remote.on "error",(e)->
					cachedPiess = null
					util.log("remote " + remoteAddr + ":" + remotePort + " error: " + e);
					if stage is 4
						connection.destroy()
					else
						connection.end()

				remote.on "drain",()->
					connection.resume()

				remote.setTimeout 3000,()=>
					connection.end()
					remote.destroy()

				if data.length > headerLength
					buf = new Buffer( data.length - headerLength)
					data.copy(buf,0,headerLength)
					cachedPiess.push buf
					buf = null
				stage = 4

			catch e
				util.log e
				connection.destroy()
				remote.destroy() if remote

		else
			cachedPiess.push(data) if stage is 4

	connection.on "end",()->
		remote.destroy() if remote

	connection.on "error",(e)->
		util.log("local error: " + e)
		remote.destroy() if remote

	connection.on "drain",()->
		remote.resume() if remote and stage is 5

	connection.setTimeout 3000,()=>
		remote.destroy() if remote
		connection.destroy()

server.on "error",(e)->
	util.log("Address in use, aborting") if e.code is "EADDRINUSE"
	process.exit 1

server.listen 1989