Simple middleware tool to test websocket connection

middle.py

## By BingLi224
## 00:57 THA 30/04/2019
##
## Simple middleware tool to test websocket connection.
##
## Use http://demos.kaazing.com/echo/ as a free websocket testing server/client.
## 1) run this script
## 2) open http://demos.kaazing.com/echo/
## 3) set "Location" to "ws://localhost:8888/echo"
## 4) monitor the connection in console

import select
import socket
import re

def middle ( ) :
	## echo server
	url = "demos.kaazing.com"

	## my server
	my_server = ( "localhost", 8888 )

	print ( "Listening [" + my_server [ 0 ] + ":" + str ( my_server [ 1 ] ) + "]" )

	## listen for browser
	serv = socket.socket ( )
	serv.bind ( my_server )
	serv.listen ( 1 )
	conn, addr = serv.accept ( )
	data = conn.recv ( 2000 ).decode ( 'utf-8' )
	host = re.findall ( r'\nHost:\s(.+?)\r?\n', data, re.MULTILINE | re.DOTALL )
	origin = re.findall ( r'\nOrigin:\s(.+?)\r?\n', data, re.MULTILINE | re.DOTALL )

	print ( "=== FROM STARTER ===" )
	print ( data )

	print ( host )
	print ( origin )

	## replace the target
	data = re.sub ( host [ 0 ], url, data, 1 ) ## will send to echo server
	data = re.sub ( origin [ 0 ], my_server [ 0 ] + ":" + str ( my_server [ 1 ] ), data, 1 ) ## from my server

	print ( "=== EDITED DATA ===" )
	print ( data )

	## conn to kaazing
	print ( "=== CONNECT TO ECHO ===" )
	echo = socket.socket ( )
	echo.connect ( ( "demos.kaazing.com", 80 ) )

	## forward to kaazing
	print ( "=== FORWARD TO ECHO ===" )
	echo.sendall ( data.encode ( 'utf-8' ) )
	
	conn.setblocking ( 0 )  ## non-block
	echo.setblocking ( 0 )  ## non-block

	readables = [ conn, echo ]

	print ( "=== WAIT FOR ANY INCOMES === " )
	while ( 1 ) :
		readable, writable, exceptions = select.select ( readables, [ ], readables, 60.0 ) 

		if not ( readable or writable or exceptions ) :
			break   ## timeout

		try :
			for r in readable :
				if r is conn :
					data = conn.recv ( 2000 )
					print ( " === FROM STARTER [%d] ===" % len(data) )
					print ( data )
					echo.sendall ( data )
					if not data :
						raise Exception
				elif r is echo :
					data = echo.recv ( 2000 )
					print ( " === FROM ECHO [%d] ===" % len(data) )
					print ( data )
					conn.sendall ( data )
					if not data :
						raise Exception
				else :
					data = r.recv ( 2000 )
					print ( " === FROM UNKNOWN === " )
					print ( data )
					if len ( data ) == 0 :
						raise Exception
		except Exception as e :
			print ( e )
			break

	## end
	echo.close ( )
	conn.close ( )

middle ( )