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
5import android_commands
6import constants
7import logging
8import os
9import subprocess
10import time
11
12
13class FakeDns(object):
14  """Wrapper class for the fake_dns tool."""
15  _FAKE_DNS_PATH = constants.TEST_EXECUTABLE_DIR + '/fake_dns'
16
17  def __init__(self, adb, build_type):
18    """
19      Args:
20        adb: the AndroidCommands to use.
21        build_type: 'Release' or 'Debug'.
22    """
23    self._adb = adb
24    self._build_type = build_type
25    self._fake_dns = None
26    self._original_dns = None
27
28  def _PushAndStartFakeDns(self):
29    """Starts the fake_dns server that replies all name queries 127.0.0.1.
30
31    Returns:
32      subprocess instance connected to the fake_dns process on the device.
33    """
34    self._adb.PushIfNeeded(
35        os.path.join(constants.CHROME_DIR, 'out', self._build_type, 'fake_dns'),
36        FakeDns._FAKE_DNS_PATH)
37    return subprocess.Popen(
38        ['adb', '-s', self._adb._adb.GetSerialNumber(),
39         'shell', '%s -D' % FakeDns._FAKE_DNS_PATH])
40
41  def SetUp(self):
42    """Configures the system to point to a DNS server that replies 127.0.0.1.
43
44    This can be used in combination with the forwarder to forward all web
45    traffic to a replay server.
46
47    The TearDown() method will perform all cleanup.
48    """
49    self._adb.RunShellCommand('ip route add 8.8.8.0/24 via 127.0.0.1 dev lo')
50    self._fake_dns = self._PushAndStartFakeDns()
51    self._original_dns = self._adb.RunShellCommand('getprop net.dns1')[0]
52    self._adb.RunShellCommand('setprop net.dns1 127.0.0.1')
53    time.sleep(2)  # Time for server to start and the setprop to take effect.
54
55  def TearDown(self):
56    """Shuts down the fake_dns."""
57    if self._fake_dns:
58      if not self._original_dns or self._original_dns == '127.0.0.1':
59        logging.warning('Bad original DNS, falling back to Google DNS.')
60        self._original_dns = '8.8.8.8'
61      self._adb.RunShellCommand('setprop net.dns1 %s' % self._original_dns)
62      self._fake_dns.kill()
63      self._adb.RunShellCommand('ip route del 8.8.8.0/24 via 127.0.0.1 dev lo')
64