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#!/usr/bin/python
# Copyright 2018 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 re
import subprocess
try:
# The following modules are required by IpForwardingUtilsIfconfig.
import netifaces
import netaddr
except ImportError:
netifaces = None
netaddr = None
IP_REGEX = re.compile(r'\A(\d{1,3}\.){3}\d{1,3}\Z')
IP_ALIAS_REGEX = re.compile(r'\A(\d{1,3}\.){3}\d{1,3}/\d{1,2}\Z')
class IpForwardingUtilsBase(object):
"""System IP address configuration utilities."""
def ParseForwardedIps(self, forwarded_ips):
"""Parse and validate forwarded IP addresses.
Args:
forwarded_ips: list, the IP address strings to parse.
Returns:
list, the valid IP address strings.
"""
pass
def GetForwardedIps(self, interface, interface_ip=None):
"""Retrieve the list of configured forwarded IP addresses.
Args:
interface: string, the output device to query.
interface_ip: string, current interface ip address.
Returns:
list, the IP address strings.
"""
pass
def AddForwardedIp(self, address, interface):
"""Configure a new IP address on the network interface.
Args:
address: string, the IP address to configure.
interface: string, the output device to use.
"""
pass
def RemoveForwardedIp(self, address, interface):
"""Delete an IP address on the network interface.
Args:
address: string, the IP address to configure.
interface: string, the output device to use.
"""
pass
class IpForwardingUtilsIproute(IpForwardingUtilsBase):
"""System IP address configuration utilities.
Command used to add IPs:
ip route add to local $IP/32 dev eth0 proto 66
Command used to fetch list of configured IPs:
ip route ls table local type local dev eth0 scope host proto 66
"""
def __init__(self, logger, proto_id=None):
"""Constructor.
Args:
logger: logger object, used to write to SysLog and serial port.
proto_id: string, the routing protocol identifier for Google IP changes.
"""
self.logger = logger
self.proto_id = proto_id or '66'
def _CreateRouteOptions(self, **kwargs):
"""Create a dictionary of parameters to append to the ip route command.
Args:
**kwargs: dict, the string parameters to update in the ip route command.
Returns:
dict, the string parameters to append to the ip route command.
"""
options = {
'proto': self.proto_id,
'scope': 'host',
}
options.update(kwargs)
return options
def _RunIpRoute(self, args=None, options=None):
"""Run a command with ip route and return the response.
Args:
args: list, the string ip route command args to execute.
options: dict, the string parameters to append to the ip route command.
Returns:
string, the standard output from the ip route command execution.
"""
args = args or []
options = options or {}
command = ['ip', 'route']
command.extend(args)
for item in options.items():
command.extend(item)
try:
process = subprocess.Popen(
command, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
stdout, stderr = process.communicate()
except OSError as e:
self.logger.warning('Exception running %s. %s.', command, str(e))
else:
if process.returncode:
message = 'Non-zero exit status running %s. %s.'
self.logger.warning(message, command, stderr.strip())
else:
return stdout.decode('utf-8', 'replace')
return ''
def ParseForwardedIps(self, forwarded_ips):
"""Parse and validate forwarded IP addresses.
Args:
forwarded_ips: list, the IP address strings to parse.
Returns:
list, the valid IP address strings.
"""
addresses = []
forwarded_ips = forwarded_ips or []
for ip in forwarded_ips:
if ip and (IP_REGEX.match(ip) or IP_ALIAS_REGEX.match(ip)):
addresses.append(ip[:-3] if ip.endswith('/32') else ip)
else:
self.logger.warning('Could not parse IP address: "%s".', ip)
return addresses
def GetForwardedIps(self, interface, interface_ip=None):
"""Retrieve the list of configured forwarded IP addresses.
Args:
interface: string, the output device to query.
interface_ip: string, current interface ip address.
Returns:
list, the IP address strings.
"""
args = ['ls', 'table', 'local', 'type', 'local']
options = self._CreateRouteOptions(dev=interface)
result = self._RunIpRoute(args=args, options=options)
result = re.sub(r'local\s', r'', result)
return self.ParseForwardedIps(result.split())
def AddForwardedIp(self, address, interface):
"""Configure a new IP address on the network interface.
Args:
address: string, the IP address to configure.
interface: string, the output device to use.
"""
address = address if IP_ALIAS_REGEX.match(address) else '%s/32' % address
args = ['add', 'to', 'local', address]
options = self._CreateRouteOptions(dev=interface)
self._RunIpRoute(args=args, options=options)
def RemoveForwardedIp(self, address, interface):
"""Delete an IP address on the network interface.
Args:
address: string, the IP address to configure.
interface: string, the output device to use.
"""
address = address if IP_ALIAS_REGEX.match(address) else '%s/32' % address
args = ['delete', 'to', 'local', address]
options = self._CreateRouteOptions(dev=interface)
self._RunIpRoute(args=args, options=options)
class IpForwardingUtilsIfconfig(IpForwardingUtilsBase):
"""System IP address configuration utilities."""
def __init__(self, logger):
"""Constructor.
Args:
logger: logger object, used to write to SysLog and serial port.
"""
self.logger = logger
def _RunIfconfig(self, args=None, options=None):
"""Run a command with ifconfig and return the response.
Args:
args: list, the string ip route command args to execute.
options: dict, the string parameters to append to the ip route command.
Returns:
string, the standard output from the ip route command execution.
"""
args = args or []
options = options or {}
command = ['ifconfig']
command.extend(args)
for item in options.items():
command.extend(item)
try:
process = subprocess.Popen(
command, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
stdout, stderr = process.communicate()
except OSError as e:
self.logger.warning('Exception running %s. %s.', command, str(e))
else:
if process.returncode:
message = 'Non-zero exit status running %s. %s.'
self.logger.warning(message, command, stderr.strip())
else:
return stdout.decode('utf-8', 'replace')
return ''
def ParseForwardedIps(self, forwarded_ips):
"""Parse and validate forwarded IP addresses.
Args:
forwarded_ips: list, the IP address strings to parse.
Returns:
list, the valid IP address strings.
"""
addresses = []
forwarded_ips = forwarded_ips or []
for ip in forwarded_ips:
if ip and (IP_REGEX.match(ip) or IP_ALIAS_REGEX.match(ip)):
addresses.extend([str(addr) for addr in list(netaddr.IPNetwork(ip))])
else:
self.logger.warning('Could not parse IP address: "%s".', ip)
return addresses
def GetForwardedIps(self, interface, interface_ip=None):
"""Retrieve the list of configured forwarded IP addresses.
Args:
interface: string, the output device to query.
interface_ip: string, current interface ip address.
Returns:
list, the IP address strings.
"""
try:
ips = netifaces.ifaddresses(interface)
ips = ips[netifaces.AF_INET]
except (ValueError, IndexError):
return []
forwarded_ips = []
for ip in ips:
if ip['addr'] != interface_ip:
full_addr = '%s/%d' % (ip['addr'], netaddr.IPAddress(ip['netmask']).netmask_bits())
forwarded_ips.append(full_addr)
return self.ParseForwardedIps(forwarded_ips)
def AddForwardedIp(self, address, interface):
"""Configure a new IP address on the network interface.
Args:
address: string, the IP address to configure.
interface: string, the output device to use.
"""
for ip in list(netaddr.IPNetwork(address)):
self._RunIfconfig(args=[interface, 'alias', '%s/32' % str(ip)])
def RemoveForwardedIp(self, address, interface):
"""Delete an IP address on the network interface.
Args:
address: string, the IP address to configure.
interface: string, the output device to use.
"""
ip = netaddr.IPNetwork(address)
self._RunIfconfig(args=[interface, '-alias', str(ip.ip)])
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