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#!/usr/bin/python
# Copyright 2016 Google Inc. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""Utilities for configuring IP address forwarding."""
import logging
import os
class NetworkUtils(object):
"""System network Ethernet interface utilities."""
def __init__(self, logger=logging):
"""Constructor.
Args:
logger: logger object, used to write to SysLog and serial port.
"""
self.logger = logger
self.interfaces = self._CreateInterfaceMap()
def _CreateInterfaceMap(self):
"""Generate a dictionary mapping MAC address to Ethernet interfaces.
Returns:
dict, string MAC addresses mapped to the string network interface name.
"""
interfaces = {}
for interface in os.listdir('/sys/class/net'):
try:
mac_address = open(
'/sys/class/net/%s/address' % interface).read().strip()
except (IOError, OSError) as e:
message = 'Unable to determine MAC address for %s. %s.'
self.logger.warning(message, interface, str(e))
else:
interfaces[mac_address] = interface
return interfaces
def GetNetworkInterface(self, mac_address):
"""Get the name of the network interface associated with a MAC address.
Args:
mac_address: string, the hardware address of the network interface.
Returns:
string, the network interface associated with a MAC address or None.
"""
return self.interfaces.get(mac_address)
def IsEnabled(self, interface):
"""Check whether a network interface is enabled.
Args:
interface: string, the network interface.
Returns:
bool, True if the network interface is enabled.
"""
try:
state = open('/sys/class/net/%s/operstate' % interface).read().strip()
except (IOError, OSError) as e:
message = 'Unable to determine the state for %s. %s.'
self.logger.warning(message, interface, str(e))
return False
else:
return 'up' == state
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