michael@0: # Copyright (c) 2012 The Chromium Authors. All rights reserved.
michael@0: # Use of this source code is governed by a BSD-style license that can be
michael@0: # found in the LICENSE file.
michael@0: 
michael@0: import android_commands
michael@0: import constants
michael@0: import logging
michael@0: import os
michael@0: import subprocess
michael@0: import time
michael@0: 
michael@0: 
michael@0: class FakeDns(object):
michael@0:   """Wrapper class for the fake_dns tool."""
michael@0:   _FAKE_DNS_PATH = constants.TEST_EXECUTABLE_DIR + '/fake_dns'
michael@0: 
michael@0:   def __init__(self, adb, build_type):
michael@0:     """
michael@0:       Args:
michael@0:         adb: the AndroidCommands to use.
michael@0:         build_type: 'Release' or 'Debug'.
michael@0:     """
michael@0:     self._adb = adb
michael@0:     self._build_type = build_type
michael@0:     self._fake_dns = None
michael@0:     self._original_dns = None
michael@0: 
michael@0:   def _PushAndStartFakeDns(self):
michael@0:     """Starts the fake_dns server that replies all name queries 127.0.0.1.
michael@0: 
michael@0:     Returns:
michael@0:       subprocess instance connected to the fake_dns process on the device.
michael@0:     """
michael@0:     self._adb.PushIfNeeded(
michael@0:         os.path.join(constants.CHROME_DIR, 'out', self._build_type, 'fake_dns'),
michael@0:         FakeDns._FAKE_DNS_PATH)
michael@0:     return subprocess.Popen(
michael@0:         ['adb', '-s', self._adb._adb.GetSerialNumber(),
michael@0:          'shell', '%s -D' % FakeDns._FAKE_DNS_PATH])
michael@0: 
michael@0:   def SetUp(self):
michael@0:     """Configures the system to point to a DNS server that replies 127.0.0.1.
michael@0: 
michael@0:     This can be used in combination with the forwarder to forward all web
michael@0:     traffic to a replay server.
michael@0: 
michael@0:     The TearDown() method will perform all cleanup.
michael@0:     """
michael@0:     self._adb.RunShellCommand('ip route add 8.8.8.0/24 via 127.0.0.1 dev lo')
michael@0:     self._fake_dns = self._PushAndStartFakeDns()
michael@0:     self._original_dns = self._adb.RunShellCommand('getprop net.dns1')[0]
michael@0:     self._adb.RunShellCommand('setprop net.dns1 127.0.0.1')
michael@0:     time.sleep(2)  # Time for server to start and the setprop to take effect.
michael@0: 
michael@0:   def TearDown(self):
michael@0:     """Shuts down the fake_dns."""
michael@0:     if self._fake_dns:
michael@0:       if not self._original_dns or self._original_dns == '127.0.0.1':
michael@0:         logging.warning('Bad original DNS, falling back to Google DNS.')
michael@0:         self._original_dns = '8.8.8.8'
michael@0:       self._adb.RunShellCommand('setprop net.dns1 %s' % self._original_dns)
michael@0:       self._fake_dns.kill()
michael@0:       self._adb.RunShellCommand('ip route del 8.8.8.0/24 via 127.0.0.1 dev lo')