Refactor au_test_harness into modules and refactor to use worker design.

bin/au_test_harness/cros_test_proxy.py

 # Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+"""Module containing various classes pertaining to inserting a proxy in a test.
+"""
+
 import os
 import select
 import socket
 import SocketServer
 import threading
 
 class Filter(object):
   """Base class for data filters.
-  
+
      Pass subclass of this to CrosTestProxy which will perform whatever
      connection manipulation you prefer.
   """
-  
+
   def setup(self):
     """This setup method is called once per connection."""
     pass
-  
+
   def InBound(self, data):
     """This method is called once per packet of incoming data.
-    
+
        The value returned is what is sent through the proxy. If
        None is returned, the connection will be closed.
     """
-    return data 
+    return data
 
   def OutBound(self, data):
     """This method is called once per packet of outgoing data.
-    
+
        The value returned is what is sent through the proxy. If
        None is returned, the connection will be closed.
     """
-    return data 
+    return data
 
 
 class CrosTestProxy(SocketServer.ThreadingMixIn, SocketServer.TCPServer):
   """A transparent proxy for simulating network errors"""
-  
+
   class _Handler(SocketServer.BaseRequestHandler):
     """Proxy connection handler that passes data though a filter"""
 
     def setup(self):
       """Setup is called once for each connection proxied."""
       self.server.filter.setup()
-  
+
     def handle(self):
       """Handles each incoming connection.
-      
+
          Opens a new connection to the port we are proxing to, then
          passes each packet along in both directions after passing
          them through the filter object passed in.
       """
       # Open outgoing socket
       s_in = self.request
       s_out = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
       s_out.connect((self.server.address_out, self.server.port_out))
 
       while True:
         rlist, wlist, xlist = select.select([s_in, s_out], [], [])
-             
+
         if s_in in rlist:
           data = s_in.recv(1024)
           data = self.server.filter.InBound(data)
           if not data: break
           try:
             # If there is any error sending data, close both connections.
             s_out.sendall(data)
           except socket.error:
             break
 
         if s_out in rlist:
           data = s_out.recv(1024)
           data = self.server.filter.OutBound(data)
           if not data: break
           try:
             # If there is any error sending data, close both connections.
             s_in.sendall(data)
           except socket.error:
             break
 
       s_in.close()
       s_out.close()
-  
+
   def __init__(self,
                filter,
                port_in=8081,
-               address_out='127.0.0.1', port_out=8080):    
+               address_out='127.0.0.1', port_out=8080):
     """Configures the proxy object.
-      
+
     Args:
       filter: An instance of a subclass of Filter.
       port_in: Port on which to listen for incoming connections.
       address_out: Address to which outgoing connections will go.
       address_port: Port to which outgoing connections will go.
     """
     self.port_in = port_in
     self.address_out = address_out
     self.port_out = port_out
     self.filter = filter
-    
+
     try:
         SocketServer.TCPServer.__init__(self,
                                         ('', port_in),
                                         self._Handler)
     except socket.error:
       os.system('sudo netstat -l --tcp -n -p')
       raise
 
   def serve_forever_in_thread(self):
     """Helper method to start the server in a new background thread."""
     server_thread = threading.Thread(target=self.serve_forever)
     server_thread.setDaemon(True)
     server_thread.start()
-    
+
     return server_thread