- Checks the OS and runs the appropriate commands for Dummynet (ipfw)

- Added pipe rule flush handling
- Also fixed a bug preventing any rule settings other than default from being 
  used no matter what preset was chosen
- Fixed some comments.

BUGS=none
TEST= Windows and linux
Review URL: https://webrtc-codereview.appspot.com/1158006

git-svn-id: http://webrtc.googlecode.com/svn/trunk@3639 4adac7df-926f-26a2-2b94-8c16560cd09d

tools/network_emulator/emulate.py

@@ -9,15 +9,16 @@
 
 """Script for constraining traffic on the local machine."""
 
+
 import logging
 import optparse
-import os
 import socket
 import sys
 
 import config
 import network_emulator
 
+
 _DEFAULT_LOG_LEVEL = logging.INFO
 
 # Default port range to apply network constraints on.
@@ -68,7 +69,7 @@ def _parse_args():
       'ID Name                       Receive     Send    Queue  Delay   loss \n'
       '-- ----                      ---------   -------- ----- ------- ------\n'
       '%s\n' % presets_string))
-  parser.add_option('-p', '--preset', type='int', default=2,
+  parser.add_option('-p', '--preset', type='int', default=_DEFAULT_PRESET_ID,
                     help=('ConnectionConfig configuration, specified by ID. '
                           'Default: %default'))
   parser.add_option('-r', '--receive-bw', type='int',
@@ -98,11 +99,11 @@ def _parse_args():
 
   options = parser.parse_args()[0]
 
-  # Find preset by ID, if specified:
+  # Find preset by ID, if specified.
   if options.preset and not _PRESETS_DICT.has_key(options.preset):
     parser.error('Invalid preset: %s' % options.preset)
 
-  # Simple validation of the IP address, if supplied:
+  # Simple validation of the IP address, if supplied.
   if options.target_ip:
     try:
       socket.inet_aton(options.target_ip)
@@ -133,27 +134,21 @@ def _set_logger(verbose):
 
 
 def _main():
-  """Checks arguments, permissions and runs a network emulation."""
-  if os.name != 'posix':
-    print >> sys.stderr, 'This script is only supported on Linux and Mac.'
-    return 1
-
   options = _parse_args()
 
   # Build a configuration object. Override any preset configuration settings if
   # a value of a setting was also given as a flag.
   connection_config = _PRESETS_DICT[options.preset]
-  if options.receive_bw:
+  if options.receive_bw is not _DEFAULT_PRESET.receive_bw_kbps:
     connection_config.receive_bw_kbps = options.receive_bw
-  if options.send_bw:
+  if options.send_bw is not _DEFAULT_PRESET.send_bw_kbps:
     connection_config.send_bw_kbps = options.send_bw
-  if options.delay:
+  if options.delay is not _DEFAULT_PRESET.delay_ms:
     connection_config.delay_ms = options.delay
-  if options.packet_loss:
+  if options.packet_loss is not _DEFAULT_PRESET.packet_loss_percent:
     connection_config.packet_loss_percent = options.packet_loss
-  if options.queue:
+  if options.queue is not _DEFAULT_PRESET.queue_slots:
     connection_config.queue_slots = options.queue
-
   emulator = network_emulator.NetworkEmulator(connection_config,
                                               options.port_range)
   try:

tools/network_emulator/network_emulator.py

@@ -9,6 +9,7 @@
 
 """Script for constraining traffic on the local machine."""
 
+import ctypes
 import logging
 import os
 import subprocess
@@ -88,21 +89,26 @@ class NetworkEmulator(object):
       NetworkEmulatorError: If permissions to run Dummynet commands are not
       available.
     """
-    if os.geteuid() != 0:
+    try:
-      _run_shell_command(
+      if os.getuid() != 0:
-          ['sudo', '-n', 'ipfw', '-h'],
+        raise NetworkEmulatorError('You must run this script with sudo.')
-          msg=('Cannot run \'ipfw\' command. This script must be run as '
+    except AttributeError:
-               'root or have password-less sudo access to this command.'))
 
-  @staticmethod
+    # AttributeError will be raised on Windows.
-  def cleanup():
+      if ctypes.windll.shell32.IsUserAnAdmin() == 0:
+        raise NetworkEmulatorError('You must run this script with administrator'
+                                   'privileges.')
+
+  def cleanup(self):
     """Stops the network emulation by flushing all Dummynet rules.
 
     Notice that this will flush any rules that may have been created previously
     before starting the emulation.
     """
-    _run_shell_command(['sudo', 'ipfw', '-f', 'flush'],
+    self._run_ipfw_command(['-f', 'flush'],
                             'Failed to flush Dummynet rules!')
+    self._run_ipfw_command(['-f', 'pipe', 'flush'],
+                            'Failed to flush Dummynet pipes!')
 
   def _create_dummynet_rule(self, pipe_id, from_address, to_address,
                             port_range):
@@ -121,11 +127,11 @@ class NetworkEmulator(object):
         each rule being added.
     """
     self._rule_counter += 100
-    add_part = ['sudo', 'ipfw', 'add', self._rule_counter, 'pipe', pipe_id,
+    add_part = ['add', self._rule_counter, 'pipe', pipe_id,
                 'ip', 'from', from_address, 'to', to_address]
-    _run_shell_command(add_part + ['src-port', '%s-%s' % port_range],
+    self._run_ipfw_command(add_part + ['src-port', '%s-%s' % port_range],
                             'Failed to add Dummynet src-port rule.')
-    _run_shell_command(add_part + ['dst-port', '%s-%s' % port_range],
+    self._run_ipfw_command(add_part + ['dst-port', '%s-%s' % port_range],
                             'Failed to add Dummynet dst-port rule.')
     return self._rule_counter
 
@@ -142,7 +148,7 @@ class NetworkEmulator(object):
         The ID of the pipe, starting at 1.
     """
     self._pipe_counter += 1
-    cmd = ['sudo', 'ipfw', 'pipe', self._pipe_counter, 'config',
+    cmd = ['pipe', self._pipe_counter, 'config',
            'bw', str(bandwidth_kbps/8) + 'KByte/s',
            'delay', '%sms' % delay_ms,
            'plr', (packet_loss_percent/100.0),
@@ -150,10 +156,13 @@ class NetworkEmulator(object):
     error_message = 'Failed to create Dummynet pipe. '
     if sys.platform.startswith('linux'):
       error_message += ('Make sure you have loaded the ipfw_mod.ko module to '
-                        'your kernel (sudo insmod /path/to/ipfw_mod.ko)')
+                        'your kernel (sudo insmod /path/to/ipfw_mod.ko).')
-    _run_shell_command(cmd, error_message)
+    self._run_ipfw_command(cmd, error_message)
     return self._pipe_counter
 
+  def _run_ipfw_command(self, command, msg=None):
+    """Executes a command and it prefixes the appropriate command for
+       Windows or Linux/UNIX.
 
 def _run_shell_command(command, msg=None):
   """Executes a command.
@@ -162,20 +171,22 @@ def _run_shell_command(command, msg=None):
     command: Command list to execute.
     msg: Message describing the error in case the command fails.
 
-  Returns:
-    The standard output from running the command.
-
     Raises:
       NetworkEmulatorError: If command fails. Message is set by the msg
       parameter.
     """
-  cmd_list = [str(x) for x in command]
+    if sys.platform == 'win32':
-  cmd = ' '.join(cmd_list)
+      ipfw_command = ['ipfw.exe']
-  logging.debug('Running command: %s', cmd)
+    else:
+      ipfw_command = ['sudo', '-n', 'ipfw']
 
+    cmd_list = ipfw_command[:] + [str(x) for x in command]
+    cmd_string = ' '.join(cmd_list)
+    logging.debug('Running command: %s', cmd_string)
     process = subprocess.Popen(cmd_list, stdout=subprocess.PIPE,
                                stderr=subprocess.PIPE)
     output, error = process.communicate()
     if process.returncode != 0:
-    raise NetworkEmulatorError(msg, cmd, process.returncode, output, error)
+      raise NetworkEmulatorError(msg, cmd_string, process.returncode, output,
+                                 error)
     return output.strip()