271 lines
9.1 KiB
Python
271 lines
9.1 KiB
Python
# vim: tabstop=4 shiftwidth=4 softtabstop=4
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# Copyright 2012 OpenStack LLC
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# All Rights Reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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import abc
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import logging
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import os
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import re
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import StringIO
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import tempfile
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import netaddr
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from quantum.agent.linux import utils
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from quantum.openstack.common import cfg
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from quantum.openstack.common import importutils
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LOG = logging.getLogger(__name__)
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OPTS = [
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cfg.StrOpt('dhcp_confs',
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default='$state_path/dhcp',
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help='Location to store DHCP server config files'),
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cfg.IntOpt('dhcp_lease_time',
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default=120,
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help='Lifetime of a DHCP lease in seconds'),
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cfg.StrOpt('dhcp_domain',
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default='openstacklocal',
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help='Domain to use for building the hostnames'),
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cfg.StrOpt('dnsmasq_config_file',
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help='Override the default dnsmasq settings with this file'),
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cfg.StrOpt('dnsmasq_dns_server',
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help='Use another DNS server before any in /etc/resolv.conf.'),
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]
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IPV4 = 4
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IPV6 = 6
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UDP = 'udp'
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TCP = 'tcp'
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DNS_PORT = 53
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DHCPV4_PORT = 67
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DHCPV6_PORT = 467
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class DhcpBase(object):
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__metaclass__ = abc.ABCMeta
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def __init__(self, conf, network, root_helper='sudo',
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device_delegate=None):
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self.conf = conf
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self.network = network
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self.root_helper = root_helper
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self.device_delegate = device_delegate
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@abc.abstractmethod
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def enable(self):
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"""Enables DHCP for this network."""
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@abc.abstractmethod
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def disable(self):
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"""Disable dhcp for this network."""
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def restart(self):
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"""Restart the dhcp service for the network."""
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self.disable()
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self.enable()
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@abc.abstractproperty
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def active(self):
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"""Boolean representing the running state of the DHCP server."""
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@abc.abstractmethod
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def reload_allocations(self):
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"""Force the DHCP server to reload the assignment database."""
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class DhcpLocalProcess(DhcpBase):
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PORTS = []
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def enable(self):
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"""Enables DHCP for this network by spawning a local process."""
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if self.active:
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self.reload_allocations()
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return
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self.device_delegate.setup(self.network, reuse_existing=True)
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self.spawn_process()
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def disable(self):
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"""Disable DHCP for this network by killing the local process."""
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pid = self.pid
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if self.active:
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utils.execute(['kill', '-9', pid], self.root_helper)
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self.device_delegate.destroy(self.network)
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elif pid:
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LOG.debug(_('DHCP for %s pid %d is stale, ignoring command') %
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(self.network.id, pid))
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else:
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LOG.debug(_('No DHCP started for %s') % self.network.id)
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def get_conf_file_name(self, kind, ensure_conf_dir=False):
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"""Returns the file name for a given kind of config file."""
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confs_dir = os.path.abspath(os.path.normpath(self.conf.dhcp_confs))
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conf_dir = os.path.join(confs_dir, self.network.id)
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if ensure_conf_dir:
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if not os.path.isdir(conf_dir):
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os.makedirs(conf_dir, 0755)
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return os.path.join(conf_dir, kind)
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def _get_value_from_conf_file(self, kind, converter=None):
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"""A helper function to read a value from one of the state files."""
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file_name = self.get_conf_file_name(kind)
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msg = _('Error while reading %s')
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try:
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with open(file_name, 'r') as f:
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try:
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return converter and converter(f.read()) or f.read()
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except ValueError, e:
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msg = _('Unable to convert value in %s')
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except IOError, e:
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msg = _('Unable to access %s')
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LOG.debug(msg % file_name)
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return None
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@property
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def pid(self):
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"""Last known pid for the DHCP process spawned for this network."""
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return self._get_value_from_conf_file('pid', int)
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@property
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def active(self):
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pid = self.pid
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cmd = ['cat', '/proc/%s/cmdline' % pid]
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try:
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return self.network.id in utils.execute(cmd, self.root_helper)
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except RuntimeError, e:
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return False
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@abc.abstractmethod
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def spawn_process(self):
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pass
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class Dnsmasq(DhcpLocalProcess):
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# The ports that need to be opened when security policies are active
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# on the Quantum port used for DHCP. These are provided as a convenience
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# for users of this class.
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PORTS = {IPV4: [(UDP, DNS_PORT), (TCP, DNS_PORT), (UDP, DHCPV4_PORT)],
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IPV6: [(UDP, DNS_PORT), (TCP, DNS_PORT), (UDP, DHCPV6_PORT)],
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}
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_TAG_PREFIX = 'tag%d'
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def spawn_process(self):
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"""Spawns a Dnsmasq process for the network."""
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interface_name = self.device_delegate.get_interface_name(self.network)
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cmd = [
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'NETWORK_ID=%s' % self.network.id,
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# TODO (mark): this is dhcpbridge script we'll need to know
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# when an IP address has been released
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'dnsmasq',
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'--no-hosts',
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'--no-resolv',
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'--strict-order',
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'--bind-interfaces',
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'--interface=%s' % interface_name,
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'--except-interface=lo',
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'--domain=%s' % self.conf.dhcp_domain,
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'--pid-file=%s' % self.get_conf_file_name('pid',
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ensure_conf_dir=True),
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#TODO (mark): calculate value from cidr (defaults to 150)
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#'--dhcp-lease-max=%s' % ?,
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'--dhcp-hostsfile=%s' % self._output_hosts_file(),
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'--dhcp-optsfile=%s' % self._output_opts_file(),
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'--leasefile-ro',
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]
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for i, subnet in enumerate(self.network.subnets):
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if subnet.ip_version == 4:
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mode = 'static'
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else:
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# TODO (mark): how do we indicate other options
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# ra-only, slaac, ra-nameservers, and ra-stateless.
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mode = 'static'
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cmd.append('--dhcp-range=set:%s,%s,%s,%ss' %
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(self._TAG_PREFIX % i,
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netaddr.IPNetwork(subnet.cidr).network,
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mode,
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self.conf.dhcp_lease_time))
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if self.conf.dnsmasq_config_file:
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cmd.append('--conf-file=%s' % self.conf.dnsmasq_config_file)
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if self.conf.dnsmasq_dns_server:
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cmd.append('--server=%s' % self.conf.dnsmasq_dns_server)
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utils.execute(cmd, self.root_helper)
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def reload_allocations(self):
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"""Rebuilds the dnsmasq config and signal the dnsmasq to reload."""
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self._output_hosts_file()
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self._output_opts_file()
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utils.execute(['kill', '-HUP', self.pid], self.root_helper)
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LOG.debug(_('Reloading allocations for network: %s') % self.network.id)
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def _output_hosts_file(self):
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"""Writes a dnsmasq compatible hosts file."""
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r = re.compile('[:.]')
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buf = StringIO.StringIO()
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for port in self.network.ports:
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for alloc in port.fixed_ips:
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name = '%s.%s' % (r.sub('-', alloc.ip_address),
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self.conf.dhcp_domain)
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buf.write('%s,%s,%s\n' %
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(port.mac_address, name, alloc.ip_address))
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name = self.get_conf_file_name('host')
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replace_file(name, buf.getvalue())
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return name
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def _output_opts_file(self):
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"""Write a dnsmasq compatible options file."""
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# TODO (mark): add support for nameservers
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options = []
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for i, subnet in enumerate(self.network.subnets):
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if subnet.ip_version == 6:
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continue
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else:
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options.append((self._TAG_PREFIX % i,
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'option',
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'router',
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subnet.gateway_ip))
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name = self.get_conf_file_name('opts')
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replace_file(name, '\n'.join(['tag:%s,%s:%s,%s' % o for o in options]))
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return name
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def replace_file(file_name, data):
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"""Replaces the contents of file_name with data in a safe manner.
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First write to a temp file and then rename. Since POSIX renames are
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atomic, the file is unlikely to be corrupted by competing writes.
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We create the tempfile on the same device to ensure that it can be renamed.
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"""
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base_dir = os.path.dirname(os.path.abspath(file_name))
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tmp_file = tempfile.NamedTemporaryFile('w+', dir=base_dir, delete=False)
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tmp_file.write(data)
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tmp_file.close()
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os.chmod(tmp_file.name, 0644)
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os.rename(tmp_file.name, file_name)
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