media/tools/constrained_network_server/cn.py

   1 #!/usr/bin/env python
   2 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
   3 # Use of this source code is governed by a BSD-style license that can be
   4 # found in the LICENSE file.
   5
   6 """A script for configuring constraint networks.
   7
   8 Sets up a constrained network configuration on a specific port. Traffic on this
   9 port will be redirected to another local server port.
  10
  11 The configuration includes bandwidth, latency, and packet loss.
  12 """
  13
  14 import collections
  15 import logging
  16 import optparse
  17 import traffic_control
  18
  19 # Default logging is ERROR. Use --verbose to enable DEBUG logging.
  20 _DEFAULT_LOG_LEVEL = logging.ERROR
  21
  22 Dispatcher = collections.namedtuple('Dispatcher', ['dispatch', 'requires_ports',
  23                                                    'desc'])
  24
  25 # Map of command names to traffic_control functions.
  26 COMMANDS = {
  27     # Adds a new constrained network configuration.
  28     'add': Dispatcher(traffic_control.CreateConstrainedPort,
  29                       requires_ports=True, desc='Add a new constrained port.'),
  30
  31     # Deletes an existing constrained network configuration.
  32     'del': Dispatcher(traffic_control.DeleteConstrainedPort,
  33                       requires_ports=True, desc='Delete a constrained port.'),
  34
  35     # Deletes all constrained network configurations.
  36     'teardown': Dispatcher(traffic_control.TearDown,
  37                            requires_ports=False,
  38                            desc='Teardown all constrained ports.')
  39 }
  40
  41
  42 def _ParseArgs():
  43   """Define and parse command-line arguments.
  44
  45   Returns:
  46     tuple as (command, configuration):
  47     command: one of the possible commands to setup, delete or teardown the
  48              constrained network.
  49     configuration: a map of constrained network properties to their values.
  50   """
  51   parser = optparse.OptionParser()
  52
  53   indent_first = parser.formatter.indent_increment
  54   opt_width = parser.formatter.help_position - indent_first
  55
  56   cmd_usage = []
  57   for s in COMMANDS:
  58     cmd_usage.append('%*s%-*s%s' %
  59                      (indent_first, '', opt_width, s, COMMANDS[s].desc))
  60
  61   parser.usage = ('usage: %%prog {%s} [options]\n\n%s' %
  62                   ('|'.join(COMMANDS.keys()), '\n'.join(cmd_usage)))
  63
  64   parser.add_option('--port', type='int',
  65                     help='The port to apply traffic control constraints to.')
  66   parser.add_option('--server-port', type='int',
  67                     help='Port to forward traffic on --port to.')
  68   parser.add_option('--bandwidth', type='int',
  69                     help='Bandwidth of the network in kbit/s.')
  70   parser.add_option('--latency', type='int',
  71                     help=('Latency (delay) added to each outgoing packet in '
  72                           'ms.'))
  73   parser.add_option('--loss', type='int',
  74                     help='Packet-loss percentage on outgoing packets. ')
  75   parser.add_option('--interface', type='string',
  76                     help=('Interface to setup constraints on. Use "lo" for a '
  77                           'local client.'))
  78   parser.add_option('-v', '--verbose', action='store_true', dest='verbose',
  79                     default=False, help='Turn on verbose output.')
  80   options, args = parser.parse_args()
  81
  82   _SetLogger(options.verbose)
  83
  84   # Check a valid command was entered
  85   if not args or args[0].lower() not in COMMANDS:
  86     parser.error('Please specify a command {%s}.' % '|'.join(COMMANDS.keys()))
  87   user_cmd = args[0].lower()
  88
  89   # Check if required options are available
  90   if COMMANDS[user_cmd].requires_ports:
  91     if not (options.port and options.server_port):
  92       parser.error('Please provide port and server-port values.')
  93
  94   config = {
  95       'port': options.port,
  96       'server_port': options.server_port,
  97       'interface': options.interface,
  98       'latency': options.latency,
  99       'bandwidth': options.bandwidth,
 100       'loss': options.loss
 101   }
 102   return user_cmd, config
 103
 104
 105 def _SetLogger(verbose):
 106   log_level = _DEFAULT_LOG_LEVEL
 107   if verbose:
 108     log_level = logging.DEBUG
 109   logging.basicConfig(level=log_level, format='%(message)s')
 110
 111
 112 def Main():
 113   """Get the command and configuration of the network to set up."""
 114   user_cmd, config = _ParseArgs()
 115
 116   try:
 117     COMMANDS[user_cmd].dispatch(config)
 118   except traffic_control.TrafficControlError as e:
 119     logging.error('Error: %s\n\nOutput: %s', e.msg, e.error)
 120
 121
 122 if __name__ == '__main__':
 123   Main()