[android] Upstream / sync most of build/android and build/android/pylib.

build/android/pylib/fake_dns.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.
+
+import android_commands
+import constants
+import logging
+import os
+import subprocess
+import time
+
+
+class FakeDns(object):
+  """Wrapper class for the fake_dns tool."""
+  _FAKE_DNS_PATH = '/data/local/tmp/fake_dns'
+
+  def __init__(self, adb):
+    """
+      Args:
+        adb: the AndroidCommands to use.
+    """
+    self._adb = adb
+    self._fake_dns = None
+    self._original_dns = None
+
+  def _PushAndStartFakeDns(self):
+    """Starts the fake_dns server that replies all name queries 127.0.0.1.
+
+    Returns:
+      subprocess instance connected to the fake_dns process on the device.
+    """
+    self._adb.PushIfNeeded(
+        os.path.join(constants.CHROME_DIR, 'out', 'Release', 'fake_dns'),
+        FakeDns._FAKE_DNS_PATH)
+    return subprocess.Popen(
+        ['adb', '-s', self._adb._adb.GetSerialNumber(),
+         'shell', '%s -D' % FakeDns._FAKE_DNS_PATH])
+
+  def SetUp(self):
+    """Configures the system to point to a DNS server that replies 127.0.0.1.
+
+    This can be used in combination with the forwarder to forward all web
+    traffic to a replay server.
+
+    The TearDown() method will perform all cleanup.
+    """
+    self._adb.RunShellCommand('ip route add 8.8.8.0/24 via 127.0.0.1 dev lo')
+    self._fake_dns = self._PushAndStartFakeDns()
+    self._original_dns = self._adb.RunShellCommand('getprop net.dns1')[0]
+    self._adb.RunShellCommand('setprop net.dns1 127.0.0.1')
+    time.sleep(2)  # Time for server to start and the setprop to take effect.
+
+  def TearDown(self):
+    """Shuts down the fake_dns."""
+    if self._fake_dns:
+      if not self._original_dns or self._original_dns == '127.0.0.1':
+        logging.warning('Bad original DNS, falling back to Google DNS.')
+        self._original_dns = '8.8.8.8'
+      self._adb.RunShellCommand('setprop net.dns1 %s' % self._original_dns)
+      self._fake_dns.kill()
+      self._adb.RunShellCommand('ip route del 8.8.8.0/24 via 127.0.0.1 dev lo')