text: #
  #    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.
  
  import re
  
  import netaddr
  from oslo_concurrency import lockutils
  from oslo_log import log as logging
  
  from neutron.agent.linux import utils as linux_utils
  from neutron.common import constants as n_const
  from neutron.common import exceptions as n_exc
  
  LOG = logging.getLogger(__name__)
  CONTRACK_MGRS = {}
  MAX_CONNTRACK_ZONES = 65535
  
  
  @lockutils.synchronized('conntrack')
  def get_conntrack(get_rules_for_table_func, filtered_ports, unfiltered_ports,
                    execute=None, namespace=None, zone_per_port=False):
      try:
          return CONTRACK_MGRS[namespace]
      except KeyError:
          ipconntrack = IpConntrackManager(get_rules_for_table_func,
                                           filtered_ports, unfiltered_ports,
                                           execute, namespace, zone_per_port)
          CONTRACK_MGRS[namespace] = ipconntrack
          return CONTRACK_MGRS[namespace]
  
  
  class IpConntrackManager(object):
      """Smart wrapper for ip conntrack."""
  
      def __init__(self, get_rules_for_table_func, filtered_ports,
                   unfiltered_ports, execute=None, namespace=None,
                   zone_per_port=False):
          self.get_rules_for_table_func = get_rules_for_table_func
          self.execute = execute or linux_utils.execute
          self.namespace = namespace
          self.filtered_ports = filtered_ports
          self.unfiltered_ports = unfiltered_ports
          self.zone_per_port = zone_per_port  # zone per port vs per network
          self._populate_initial_zone_map()
  
      @staticmethod
      def _generate_conntrack_cmd_by_rule(rule, namespace):
          ethertype = rule.get('ethertype')
          protocol = rule.get('protocol')
          direction = rule.get('direction')
          cmd = ['conntrack', '-D']
          if protocol:
              cmd.extend(['-p', str(protocol)])
          cmd.extend(['-f', str(ethertype).lower()])
          cmd.append('-d' if direction == 'ingress' else '-s')
          cmd_ns = []
          if namespace:
              cmd_ns.extend(['ip', 'netns', 'exec', namespace])
          cmd_ns.extend(cmd)
          return cmd_ns
  
      def _get_conntrack_cmds(self, device_info_list, rule, remote_ip=None):
          conntrack_cmds = set()
          cmd = self._generate_conntrack_cmd_by_rule(rule, self.namespace)
          ethertype = rule.get('ethertype')
          for device_info in device_info_list:
              zone_id = self.get_device_zone(device_info, create=False)
              if not zone_id:
                  LOG.debug("No zone for device %(dev)s. Will not try to "
                            "clear conntrack state. Zone map: %(zm)s",
                            {'dev': device_info['device'],
                             'zm': self._device_zone_map})
                  continue
              ips = device_info.get('fixed_ips', [])
              for ip in ips:
                  net = netaddr.IPNetwork(ip)
                  if str(net.version) not in ethertype:
                      continue
                  ip_cmd = [str(net.ip), '-w', zone_id]
                  if remote_ip and str(
                          netaddr.IPNetwork(remote_ip).version) in ethertype:
                      if rule.get('direction') == 'ingress':
                          direction = '-s'
                      else:
                          direction = '-d'
                      ip_cmd.extend([direction, str(remote_ip)])
                  conntrack_cmds.add(tuple(cmd + ip_cmd))
          return conntrack_cmds
  
      def _delete_conntrack_state(self, device_info_list, rule, remote_ip=None):
          conntrack_cmds = self._get_conntrack_cmds(device_info_list,
                                                    rule, remote_ip)
          for cmd in conntrack_cmds:
              try:
                  self.execute(list(cmd), run_as_root=True,
                               check_exit_code=True,
                               extra_ok_codes=[1])
              except RuntimeError:
                  LOG.exception("Failed execute conntrack command %s", cmd)
  
      def delete_conntrack_state_by_rule(self, device_info_list, rule):
          self._delete_conntrack_state(device_info_list, rule)
  
      def delete_conntrack_state_by_remote_ips(self, device_info_list,
                                               ethertype, remote_ips):
          for direction in ['ingress', 'egress']:
              rule = {'ethertype': str(ethertype).lower(),
                      'direction': direction}
              if remote_ips:
                  for remote_ip in remote_ips:
                      self._delete_conntrack_state(
                          device_info_list, rule, remote_ip)
              else:
                  self._delete_conntrack_state(device_info_list, rule)
  
      def _populate_initial_zone_map(self):
          """Setup the map between devices and zones based on current rules."""
          self._device_zone_map = {}
          rules = self.get_rules_for_table_func('raw')
          for rule in rules:
              match = re.match(r'.* --physdev-in (?P<dev>[a-zA-Z0-9\-]+)'
                               r'.* -j CT --zone (?P<zone>\d+).*', rule)
              if match:
                  # strip off any prefix that the interface is using
                  short_port_id = (match.group('dev')
                      [n_const.LINUX_DEV_PREFIX_LEN:])
                  self._device_zone_map[short_port_id] = int(match.group('zone'))
          LOG.debug("Populated conntrack zone map: %s", self._device_zone_map)
  
      def _device_key(self, port):
          # we have to key the device_zone_map based on the fragment of the
          # UUID that shows up in the interface name. This is because the initial
          # map is populated strictly based on interface names that we don't know
          # the full UUID of.
          if self.zone_per_port:
              identifier = port['device'][n_const.LINUX_DEV_PREFIX_LEN:]
          else:
              identifier = port['network_id']
          return identifier[:(n_const.LINUX_DEV_LEN -
                            n_const.LINUX_DEV_PREFIX_LEN)]
  
      def get_device_zone(self, port, create=True):
          device_key = self._device_key(port)
          try:
              return self._device_zone_map[device_key]
          except KeyError:
              if create:
                  return self._generate_device_zone(device_key)
  
      def _free_zones_from_removed_ports(self):
          """Clears any entries from the zone map of removed ports."""
          existing_ports = [
              self._device_key(port)
              for port in (list(self.filtered_ports.values()) +
                           list(self.unfiltered_ports.values()))
          ]
          removed = set(self._device_zone_map) - set(existing_ports)
          for dev in removed:
              self._device_zone_map.pop(dev, None)
  
      def _generate_device_zone(self, short_device_id):
          """Generates a unique conntrack zone for the passed in ID."""
          try:
              zone = self._find_open_zone()
          except n_exc.CTZoneExhaustedError:
              # Free some zones and try again, repeat failure will not be caught
              self._free_zones_from_removed_ports()
              zone = self._find_open_zone()
  
          self._device_zone_map[short_device_id] = zone
          LOG.debug("Assigned CT zone %(z)s to device %(dev)s.",
                    {'z': zone, 'dev': short_device_id})
          return self._device_zone_map[short_device_id]
  
      def _find_open_zone(self):
          # call set to dedup because old ports may be mapped to the same zone.
          zones_in_use = sorted(set(self._device_zone_map.values()))
          if not zones_in_use:
              return 1
          # attempt to increment onto the highest used zone first. if we hit the
          # end, go back and look for any gaps left by removed devices.
          last = zones_in_use[-1]
          if last < MAX_CONNTRACK_ZONES:
              return last + 1
          for index, used in enumerate(zones_in_use):
              if used - index != 1:
                  # gap found, let's use it!
                  return index + 1
          # conntrack zones exhausted :( :(
          raise n_exc.CTZoneExhaustedError()
  