Make host port availability detection more robust.

build/android/pylib/ports.py

 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """Functions that deal with local and device ports."""
 
 import contextlib
 import fcntl
 import httplib
 import logging
 import os
-import re
 import socket
 import traceback
 
-from pylib import cmd_helper
 from pylib import constants
 
 
 # The following two methods are used to allocate the port source for various
 # types of test servers. Because some net-related tests can be run on shards at
 # same time, it's important to have a mechanism to allocate the port
 # process-safe. In here, we implement the safe port allocation by leveraging
 # flock.
 def ResetTestServerPortAllocation():
   """Resets the port allocation to start from TEST_SERVER_PORT_FIRST.
@@ skipping 23 matching lines @@
   ports_tried = []
   try:
     fp_lock = open(constants.TEST_SERVER_PORT_LOCKFILE, 'w')
     fcntl.flock(fp_lock, fcntl.LOCK_EX)
     # Get current valid port and calculate next valid port.
     if not os.path.exists(constants.TEST_SERVER_PORT_FILE):
       ResetTestServerPortAllocation()
     with open(constants.TEST_SERVER_PORT_FILE, 'r+') as fp:
       port = int(fp.read())
       ports_tried.append(port)
-      while IsHostPortUsed(port):
+      while not IsHostPortAvailable(port):
         port += 1
         ports_tried.append(port)
       if (port > constants.TEST_SERVER_PORT_LAST or
           port < constants.TEST_SERVER_PORT_FIRST):
         port = 0
       else:
         fp.seek(0, os.SEEK_SET)
         fp.write('%d' % (port + 1))
   except Exception as e:
-    logging.info(e)
+    logging.error(e)
   finally:
     if fp_lock:
       fcntl.flock(fp_lock, fcntl.LOCK_UN)
       fp_lock.close()
   if port:
     logging.info('Allocate port %d for test server.', port)
   else:
     logging.error('Could not allocate port for test server. '
                   'List of ports tried: %s', str(ports_tried))
   return port
 
 
-def IsHostPortUsed(host_port):
-  """Checks whether the specified host port is used or not.
-
-  Uses -n -P to inhibit the conversion of host/port numbers to host/port names.
+def IsHostPortAvailable(host_port):
+  """Checks whether the specified host port is available.
 
   Args:
-    host_port: Port on host we want to check.
+    host_port: Port on host to check.
 
   Returns:
-    True if the port on host is already used, otherwise returns False.
+    True if the port on host is available, otherwise returns False.
   """
-  port_info = '(\*)|(127\.0\.0\.1)|(localhost):%d' % host_port
-  # TODO(jnd): Find a better way to filter the port. Note that connecting to the
-  # socket and closing it would leave it in the TIME_WAIT state. Setting
-  # SO_LINGER on it and then closing it makes the Python HTTP server crash.
-  re_port = re.compile(port_info, re.MULTILINE)
-  if re_port.search(cmd_helper.GetCmdOutput(['lsof', '-nPi:%d' % host_port])):
+  s = socket.socket()
+  try:
+    s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
+    s.bind(('', host_port))
+    s.close()
     return True
-  return False
+  except socket.error:
+    return False
 
 
 def IsDevicePortUsed(device, device_port, state=''):
   """Checks whether the specified device port is used or not.
 
   Args:
     device: A DeviceUtils instance.
     device_port: Port on device we want to check.
     state: String of the specified state. Default is empty string, which
            means any state.
@@ skipping 55 matching lines @@
         client_error = ('Bad response: %s %s version %s\n  ' %
                         (r.status, r.reason, r.version) +
                         '\n  '.join([': '.join(h) for h in r.getheaders()]))
     except (httplib.HTTPException, socket.error) as e:
       # Probably too quick connecting: try again.
       exception_error_msgs = traceback.format_exception_only(type(e), e)
       if exception_error_msgs:
         client_error = ''.join(exception_error_msgs)
   # Only returns last client_error.
   return (False, client_error or 'Timeout')