build/android/pylib/ports.py

   1 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 # Use of this source code is governed by a BSD-style license that can be
   3 # found in the LICENSE file.
   4
   5 """Functions that deal with local and device ports."""
   6
   7 import contextlib
   8 import fcntl
   9 import httplib
  10 import logging
  11 import os
  12 import socket
  13 import traceback
  14
  15 from pylib import constants
  16
  17
  18 # The following two methods are used to allocate the port source for various
  19 # types of test servers. Because some net-related tests can be run on shards at
  20 # same time, it's important to have a mechanism to allocate the port
  21 # process-safe. In here, we implement the safe port allocation by leveraging
  22 # flock.
  23 def ResetTestServerPortAllocation():
  24   """Resets the port allocation to start from TEST_SERVER_PORT_FIRST.
  25
  26   Returns:
  27     Returns True if reset successes. Otherwise returns False.
  28   """
  29   try:
  30     with open(constants.TEST_SERVER_PORT_FILE, 'w') as fp:
  31       fp.write('%d' % constants.TEST_SERVER_PORT_FIRST)
  32     if os.path.exists(constants.TEST_SERVER_PORT_LOCKFILE):
  33       os.unlink(constants.TEST_SERVER_PORT_LOCKFILE)
  34     return True
  35   except Exception as e:
  36     logging.error(e)
  37   return False
  38
  39
  40 def AllocateTestServerPort():
  41   """Allocates a port incrementally.
  42
  43   Returns:
  44     Returns a valid port which should be in between TEST_SERVER_PORT_FIRST and
  45     TEST_SERVER_PORT_LAST. Returning 0 means no more valid port can be used.
  46   """
  47   port = 0
  48   ports_tried = []
  49   try:
  50     fp_lock = open(constants.TEST_SERVER_PORT_LOCKFILE, 'w')
  51     fcntl.flock(fp_lock, fcntl.LOCK_EX)
  52     # Get current valid port and calculate next valid port.
  53     if not os.path.exists(constants.TEST_SERVER_PORT_FILE):
  54       ResetTestServerPortAllocation()
  55     with open(constants.TEST_SERVER_PORT_FILE, 'r+') as fp:
  56       port = int(fp.read())
  57       ports_tried.append(port)
  58       while not IsHostPortAvailable(port):
  59         port += 1
  60         ports_tried.append(port)
  61       if (port > constants.TEST_SERVER_PORT_LAST or
  62           port < constants.TEST_SERVER_PORT_FIRST):
  63         port = 0
  64       else:
  65         fp.seek(0, os.SEEK_SET)
  66         fp.write('%d' % (port + 1))
  67   except Exception as e:
  68     logging.error(e)
  69   finally:
  70     if fp_lock:
  71       fcntl.flock(fp_lock, fcntl.LOCK_UN)
  72       fp_lock.close()
  73   if port:
  74     logging.info('Allocate port %d for test server.', port)
  75   else:
  76     logging.error('Could not allocate port for test server. '
  77                   'List of ports tried: %s', str(ports_tried))
  78   return port
  79
  80
  81 def IsHostPortAvailable(host_port):
  82   """Checks whether the specified host port is available.
  83
  84   Args:
  85     host_port: Port on host to check.
  86
  87   Returns:
  88     True if the port on host is available, otherwise returns False.
  89   """
  90   s = socket.socket()
  91   try:
  92     s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
  93     s.bind(('', host_port))
  94     s.close()
  95     return True
  96   except socket.error:
  97     return False
  98
  99
 100 def IsDevicePortUsed(device, device_port, state=''):
 101   """Checks whether the specified device port is used or not.
 102
 103   Args:
 104     device: A DeviceUtils instance.
 105     device_port: Port on device we want to check.
 106     state: String of the specified state. Default is empty string, which
 107            means any state.
 108
 109   Returns:
 110     True if the port on device is already used, otherwise returns False.
 111   """
 112   base_url = '127.0.0.1:%d' % device_port
 113   netstat_results = device.RunShellCommand('netstat')
 114   for single_connect in netstat_results:
 115     # Column 3 is the local address which we want to check with.
 116     connect_results = single_connect.split()
 117     if connect_results[0] != 'tcp':
 118       continue
 119     if len(connect_results) < 6:
 120       raise Exception('Unexpected format while parsing netstat line: ' +
 121                       single_connect)
 122     is_state_match = connect_results[5] == state if state else True
 123     if connect_results[3] == base_url and is_state_match:
 124       return True
 125   return False
 126
 127
 128 def IsHttpServerConnectable(host, port, tries=3, command='GET', path='/',
 129                             expected_read='', timeout=2):
 130   """Checks whether the specified http server is ready to serve request or not.
 131
 132   Args:
 133     host: Host name of the HTTP server.
 134     port: Port number of the HTTP server.
 135     tries: How many times we want to test the connection. The default value is
 136            3.
 137     command: The http command we use to connect to HTTP server. The default
 138              command is 'GET'.
 139     path: The path we use when connecting to HTTP server. The default path is
 140           '/'.
 141     expected_read: The content we expect to read from the response. The default
 142                    value is ''.
 143     timeout: Timeout (in seconds) for each http connection. The default is 2s.
 144
 145   Returns:
 146     Tuple of (connect status, client error). connect status is a boolean value
 147     to indicate whether the server is connectable. client_error is the error
 148     message the server returns when connect status is false.
 149   """
 150   assert tries >= 1
 151   for i in xrange(0, tries):
 152     client_error = None
 153     try:
 154       with contextlib.closing(httplib.HTTPConnection(
 155           host, port, timeout=timeout)) as http:
 156         # Output some debug information when we have tried more than 2 times.
 157         http.set_debuglevel(i >= 2)
 158         http.request(command, path)
 159         r = http.getresponse()
 160         content = r.read()
 161         if r.status == 200 and r.reason == 'OK' and content == expected_read:
 162           return (True, '')
 163         client_error = ('Bad response: %s %s version %s\n  ' %
 164                         (r.status, r.reason, r.version) +
 165                         '\n  '.join([': '.join(h) for h in r.getheaders()]))
 166     except (httplib.HTTPException, socket.error) as e:
 167       # Probably too quick connecting: try again.
 168       exception_error_msgs = traceback.format_exception_only(type(e), e)
 169       if exception_error_msgs:
 170         client_error = ''.join(exception_error_msgs)
 171   # Only returns last client_error.
 172   return (False, client_error or 'Timeout')