Use different proxy ports, and log port conflicts. Hopefully works around

build problems, and will give better diagnostics if not.

Change-Id: I2f7a5d9b2e0c63a8189ad212125c7a5c0178c3c4

BUG=10567
TEST=

Review URL: http://codereview.chromium.org/6331007

bin/cros_au_test_harness.py

@@ -139,15 +139,14 @@ class AUTest(object):
     Warning(err.stdout)
     self.fail('We managed to update when failure was expected')
 
-  def AttemptUpdateWithFilter(self, filter):
+  def AttemptUpdateWithFilter(self, filter, proxy_port=8081):
     """Update through a proxy, with a specified filter, and expect success."""
 
     self.PrepareBase(self.target_image_path)
 
     # The devserver runs at port 8080 by default. We assume that here, and
-    # start our proxy at 8081. We then tell our update tools to have the
-    # client connect to 8081 instead of 8080.
-    proxy_port = 8081
+    # start our proxy at a different. We then tell our update tools to
+    # have the client connect to our proxy_port instead of 8080.
     proxy = cros_test_proxy.CrosTestProxy(port_in=proxy_port,
                                           address_out='127.0.0.1',
                                           port_out=8080,
@@ -350,7 +349,7 @@ class AUTest(object):
         self.data_size += len(data)
         return data
 
-    self.AttemptUpdateWithFilter(InterruptionFilter())
+    self.AttemptUpdateWithFilter(InterruptionFilter(), proxy_port=8082)
 
   def testDelayedUpdate(self):
     """Tests what happens if some data is delayed during update delivery"""
@@ -380,7 +379,7 @@ class AUTest(object):
         self.data_size += len(data)
         return data
 
-    self.AttemptUpdateWithFilter(DelayedFilter())
+    self.AttemptUpdateWithFilter(DelayedFilter(), proxy_port=8083)
 
   def SimpleTest(self):
     """A simple update that updates once from a base image to a target.

lib/cros_test_proxy.py

@@ -2,6 +2,7 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import os
 import select
 import socket
 import SocketServer
@@ -100,9 +101,13 @@ class CrosTestProxy(SocketServer.ThreadingMixIn, SocketServer.TCPServer):
     self.port_out = port_out
     self.filter = filter
     
-    SocketServer.TCPServer.__init__(self,
-                                    ('', port_in),
-                                    self._Handler)
+    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."""