text: # Copyright (c) 2015 OpenStack Foundation
  #
  #    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 binascii
  import collections
  
  import netaddr
  from neutron_lib import constants as lib_constants
  from neutron_lib import exceptions
  from oslo_log import log as logging
  from oslo_utils import excutils
  import six
  
  from neutron.agent.l3 import dvr_fip_ns
  from neutron.agent.l3 import dvr_router_base
  from neutron.agent.linux import ip_lib
  from neutron.common import constants as n_const
  from neutron.common import utils as common_utils
  
  LOG = logging.getLogger(__name__)
  # xor-folding mask used for IPv6 rule index
  MASK_30 = 0x3fffffff
  
  # Tracks the arp entry cache
  Arp_entry = collections.namedtuple(
      'Arp_entry', 'ip mac subnet_id operation')
  
  
  class DvrLocalRouter(dvr_router_base.DvrRouterBase):
      def __init__(self, host, *args, **kwargs):
          super(DvrLocalRouter, self).__init__(host, *args, **kwargs)
  
          self.floating_ips_dict = {}
          # Linklocal subnet for router and floating IP namespace link
          self.rtr_fip_subnet = None
          self.rtr_fip_connect = False
          self.fip_ns = None
          self._pending_arp_set = set()
  
      def migrate_centralized_floating_ip(self, fip, interface_name, device):
          # Remove the centralized fip first and then add fip to the host
          ip_cidr = common_utils.ip_to_cidr(fip['floating_ip_address'])
          self.floating_ip_removed_dist(ip_cidr)
          # Now add the floating_ip to the current host
          self.floating_ip_added_dist(fip, ip_cidr)
  
      def floating_forward_rules(self, fip):
          """Override this function defined in router_info for dvr routers."""
          if not self.fip_ns:
              return []
  
          if fip.get(lib_constants.DVR_SNAT_BOUND):
              return []
  
          # For dvr_no_external node should not process any floating IP
          # iptables rules.
          if (self.agent_conf.agent_mode ==
                  lib_constants.L3_AGENT_MODE_DVR_NO_EXTERNAL):
              return []
  
          fixed_ip = fip['fixed_ip_address']
          floating_ip = fip['floating_ip_address']
          rtr_2_fip_name = self.fip_ns.get_rtr_ext_device_name(self.router_id)
          dnat_from_floatingip_to_fixedip = (
              'PREROUTING', '-d %s/32 -i %s -j DNAT --to-destination %s' % (
                  floating_ip, rtr_2_fip_name, fixed_ip))
          snat_from_fixedip_to_floatingip = (
              'float-snat', '-s %s/32 -j SNAT --to-source %s' % (
                  fixed_ip, floating_ip))
          return [dnat_from_floatingip_to_fixedip,
                  snat_from_fixedip_to_floatingip]
  
      def floating_mangle_rules(self, floating_ip, fixed_ip, internal_mark):
          if not self.fip_ns:
              return []
  
          rtr_2_fip_name = self.fip_ns.get_rtr_ext_device_name(self.router_id)
          mark_traffic_to_floating_ip = (
              'floatingip', '-d %s/32 -i %s -j MARK --set-xmark %s' % (
                  floating_ip, rtr_2_fip_name, internal_mark))
          mark_traffic_from_fixed_ip = (
              'FORWARD', '-s %s/32 -j $float-snat' % fixed_ip)
          return [mark_traffic_to_floating_ip, mark_traffic_from_fixed_ip]
  
      def add_centralized_floatingip(self, fip, fip_cidr):
          """Implements floatingip in centralized network node.
          This is a dummy function and is overridden in dvr_edge_router.py
          to add the floatingip function to the snat namespace.
          """
  
      def remove_centralized_floatingip(self, fip_cidr):
          """Removes floatingip from centralized network node.
          This is a dummy function and is overridden in dvr_edge_router.py
          to remove the floatingip function from the snat namespace.
          """
  
      def floating_ip_added_dist(self, fip, fip_cidr):
          """Add floating IP to respective namespace based on agent mode."""
          if fip.get(lib_constants.DVR_SNAT_BOUND):
              floating_ip_status = self.add_centralized_floatingip(fip, fip_cidr)
              return floating_ip_status
          if not self._check_if_floatingip_bound_to_host(fip):
              # TODO(Swami): Need to figure out what status
              # should be returned when the floating IP is
              # not destined for this agent and if the floating
              # IP is configured in a different compute host.
              # This should not happen once we fix the server
              # side code, but still a check to make sure if
              # the floating IP is intended for this host should
              # be done.
              return
  
          # dvr_no_external host should not process any floating IP route rules.
          if (self.agent_conf.agent_mode ==
                  lib_constants.L3_AGENT_MODE_DVR_NO_EXTERNAL):
              return
  
          floating_ip = fip['floating_ip_address']
          fixed_ip = fip['fixed_ip_address']
          self._add_floating_ip_rule(floating_ip, fixed_ip)
          fip_2_rtr_name = self.fip_ns.get_int_device_name(self.router_id)
          # Add routing rule in fip namespace
          fip_ns_name = self.fip_ns.get_name()
          if self.rtr_fip_subnet is None:
              self.rtr_fip_subnet = self.fip_ns.local_subnets.allocate(
                  self.router_id)
          rtr_2_fip, __ = self.rtr_fip_subnet.get_pair()
          device = ip_lib.IPDevice(fip_2_rtr_name, namespace=fip_ns_name)
          device.route.add_route(fip_cidr, str(rtr_2_fip.ip))
          interface_name = (
              self.fip_ns.get_ext_device_name(
                  self.fip_ns.agent_gateway_port['id']))
          ip_lib.send_ip_addr_adv_notif(fip_ns_name,
                                        interface_name,
                                        floating_ip)
          return lib_constants.FLOATINGIP_STATUS_ACTIVE
  
      def _add_floating_ip_rule(self, floating_ip, fixed_ip):
          rule_pr = self.fip_ns.allocate_rule_priority(floating_ip)
          self.floating_ips_dict[floating_ip] = (fixed_ip, rule_pr)
          ip_rule = ip_lib.IPRule(namespace=self.ns_name)
          ip_rule.rule.add(ip=fixed_ip,
                           table=dvr_fip_ns.FIP_RT_TBL,
                           priority=rule_pr)
  
      def _remove_floating_ip_rule(self, floating_ip):
          if floating_ip in self.floating_ips_dict:
              fixed_ip, rule_pr = self.floating_ips_dict[floating_ip]
              ip_rule = ip_lib.IPRule(namespace=self.ns_name)
              ip_rule.rule.delete(ip=fixed_ip,
                                  table=dvr_fip_ns.FIP_RT_TBL,
                                  priority=rule_pr)
              self.fip_ns.deallocate_rule_priority(floating_ip)
              # TODO(rajeev): Handle else case - exception/log?
  
      def floating_ip_removed_dist(self, fip_cidr):
          """Remove floating IP from FIP namespace."""
          centralized_fip_cidrs = self.get_centralized_fip_cidr_set()
          if fip_cidr in centralized_fip_cidrs:
              self.remove_centralized_floatingip(fip_cidr)
              return
          floating_ip = fip_cidr.split('/')[0]
          fip_2_rtr_name = self.fip_ns.get_int_device_name(self.router_id)
          if self.rtr_fip_subnet is None:
              self.rtr_fip_subnet = self.fip_ns.local_subnets.lookup(
                  self.router_id)
          if self.rtr_fip_subnet:
              rtr_2_fip, fip_2_rtr = self.rtr_fip_subnet.get_pair()
              fip_ns_name = self.fip_ns.get_name()
              self._remove_floating_ip_rule(floating_ip)
  
              device = ip_lib.IPDevice(fip_2_rtr_name, namespace=fip_ns_name)
  
              device.route.delete_route(fip_cidr, str(rtr_2_fip.ip))
  
      def floating_ip_moved_dist(self, fip):
          """Handle floating IP move between fixed IPs."""
          floating_ip = fip['floating_ip_address']
          self._remove_floating_ip_rule(floating_ip)
          self._add_floating_ip_rule(floating_ip, fip['fixed_ip_address'])
  
      def add_floating_ip(self, fip, interface_name, device):
          # Special Handling for DVR - update FIP namespace
          ip_cidr = common_utils.ip_to_cidr(fip['floating_ip_address'])
          return self.floating_ip_added_dist(fip, ip_cidr)
  
      def remove_floating_ip(self, device, ip_cidr):
          self.floating_ip_removed_dist(ip_cidr)
  
      def move_floating_ip(self, fip):
          self.floating_ip_moved_dist(fip)
          return lib_constants.FLOATINGIP_STATUS_ACTIVE
  
      def _get_internal_port(self, subnet_id):
          """Return internal router port based on subnet_id."""
          router_ports = self.router.get(lib_constants.INTERFACE_KEY, [])
          for port in router_ports:
              fips = port['fixed_ips']
              for f in fips:
                  if f['subnet_id'] == subnet_id:
                      return port
  
      def _cache_arp_entry(self, ip, mac, subnet_id, operation):
          """Cache the arp entries if device not ready."""
          arp_entry_tuple = Arp_entry(ip=ip,
                                      mac=mac,
                                      subnet_id=subnet_id,
                                      operation=operation)
          self._pending_arp_set.add(arp_entry_tuple)
  
      def _process_arp_cache_for_internal_port(self, subnet_id):
          """Function to process the cached arp entries."""
          arp_remove = set()
          for arp_entry in self._pending_arp_set:
              if subnet_id == arp_entry.subnet_id:
                  try:
                      state = self._update_arp_entry(
                          arp_entry.ip, arp_entry.mac,
                          arp_entry.subnet_id, arp_entry.operation)
                  except Exception:
                      state = False
                  if state:
                      # If the arp update was successful, then
                      # go ahead and add it to the remove set
                      arp_remove.add(arp_entry)
  
          self._pending_arp_set -= arp_remove
  
      def _delete_arp_cache_for_internal_port(self, subnet_id):
          """Function to delete the cached arp entries."""
          arp_delete = set()
          for arp_entry in self._pending_arp_set:
              if subnet_id == arp_entry.subnet_id:
                  arp_delete.add(arp_entry)
          self._pending_arp_set -= arp_delete
  
      def _update_arp_entry(self, ip, mac, subnet_id, operation):
          """Add or delete arp entry into router namespace for the subnet."""
          port = self._get_internal_port(subnet_id)
          # update arp entry only if the subnet is attached to the router
          if not port:
              return False
  
          try:
              # TODO(mrsmith): optimize the calls below for bulk calls
              interface_name = self.get_internal_device_name(port['id'])
              device = ip_lib.IPDevice(interface_name, namespace=self.ns_name)
              if device.exists():
                  if operation == 'add':
                      device.neigh.add(ip, mac)
                  elif operation == 'delete':
                      device.neigh.delete(ip, mac)
                  return True
              else:
                  if operation == 'add':
                      LOG.warning("Device %s does not exist so ARP entry "
                                  "cannot be updated, will cache "
                                  "information to be applied later "
                                  "when the device exists",
                                  device)
                      self._cache_arp_entry(ip, mac, subnet_id, operation)
                  return False
          except Exception:
              with excutils.save_and_reraise_exception():
                  LOG.exception("DVR: Failed updating arp entry")
  
      def _set_subnet_arp_info(self, subnet_id):
          """Set ARP info retrieved from Plugin for existing ports."""
          # TODO(Carl) Can we eliminate the need to make this RPC while
          # processing a router.
          subnet_ports = self.agent.get_ports_by_subnet(subnet_id)
          ignored_device_owners = (
              lib_constants.ROUTER_INTERFACE_OWNERS +
              tuple(common_utils.get_dvr_allowed_address_pair_device_owners()))
  
          for p in subnet_ports:
              if p['device_owner'] not in ignored_device_owners:
                  for fixed_ip in p['fixed_ips']:
                      self._update_arp_entry(fixed_ip['ip_address'],
                                             p['mac_address'],
                                             subnet_id,
                                             'add')
          self._process_arp_cache_for_internal_port(subnet_id)
  
      @staticmethod
      def _get_snat_idx(ip_cidr):
          """Generate index for DVR snat rules and route tables.
  
          The index value has to be 32 bits or less but more than the system
          generated entries i.e. 32768. For IPv4 use the numeric value of the
          cidr. For IPv6 generate a crc32 bit hash and xor-fold to 30 bits.
          Use the freed range to extend smaller values so that they become
          greater than system generated entries.
          """
          net = netaddr.IPNetwork(ip_cidr)
          if net.version == 6:
              if isinstance(ip_cidr, six.text_type):
                  ip_cidr = ip_cidr.encode()  # Needed for Python 3.x
              # the crc32 & 0xffffffff is for Python 2.6 and 3.0 compatibility
              snat_idx = binascii.crc32(ip_cidr) & 0xffffffff
              # xor-fold the hash to reserve upper range to extend smaller values
              snat_idx = (snat_idx >> 30) ^ (snat_idx & MASK_30)
              if snat_idx < 32768:
                  snat_idx = snat_idx + MASK_30
          else:
              snat_idx = net.value
          return snat_idx
  
      def _delete_gateway_device_if_exists(self, ns_ip_device, gw_ip_addr,
                                           snat_idx):
          try:
              ns_ip_device.route.delete_gateway(gw_ip_addr,
                                          table=snat_idx)
          except exceptions.DeviceNotFoundError:
              pass
  
      def _stale_ip_rule_cleanup(self, ns_ipr, ns_ipd, ip_version):
          ip_rules_list = ns_ipr.rule.list_rules(ip_version)
          snat_table_list = []
          for ip_rule in ip_rules_list:
              snat_table = ip_rule['table']
              priority = ip_rule['priority']
              if snat_table in ['local', 'default', 'main']:
                  continue
              if (ip_version == lib_constants.IP_VERSION_4 and
                  snat_table in range(dvr_fip_ns.FIP_PR_START,
                                      dvr_fip_ns.FIP_PR_END)):
                  continue
              gateway_cidr = ip_rule['from']
              ns_ipr.rule.delete(ip=gateway_cidr,
                                 table=snat_table,
                                 priority=priority)
              snat_table_list.append(snat_table)
          for tb in snat_table_list:
              ns_ipd.route.flush(ip_version, table=tb)
  
      def gateway_redirect_cleanup(self, rtr_interface):
          ns_ipr = ip_lib.IPRule(namespace=self.ns_name)
          ns_ipd = ip_lib.IPDevice(rtr_interface, namespace=self.ns_name)
          self._stale_ip_rule_cleanup(ns_ipr, ns_ipd, lib_constants.IP_VERSION_4)
          self._stale_ip_rule_cleanup(ns_ipr, ns_ipd, lib_constants.IP_VERSION_6)
  
      def _snat_redirect_modify(self, gateway, sn_port, sn_int, is_add):
          """Adds or removes rules and routes for SNAT redirection."""
          cmd = ['net.ipv4.conf.%s.send_redirects=0' % sn_int]
          try:
              ns_ipr = ip_lib.IPRule(namespace=self.ns_name)
              ns_ipd = ip_lib.IPDevice(sn_int, namespace=self.ns_name)
              for port_fixed_ip in sn_port['fixed_ips']:
                  # Iterate and find the gateway IP address matching
                  # the IP version
                  port_ip_addr = port_fixed_ip['ip_address']
                  port_ip_vers = netaddr.IPAddress(port_ip_addr).version
                  for gw_fixed_ip in gateway['fixed_ips']:
                      gw_ip_addr = gw_fixed_ip['ip_address']
                      if netaddr.IPAddress(gw_ip_addr).version == port_ip_vers:
                          sn_port_cidr = common_utils.ip_to_cidr(
                              port_ip_addr, port_fixed_ip['prefixlen'])
                          snat_idx = self._get_snat_idx(sn_port_cidr)
                          if is_add:
                              ns_ipd.route.add_gateway(gw_ip_addr,
                                                       table=snat_idx)
                              ns_ipr.rule.add(ip=sn_port_cidr,
                                              table=snat_idx,
                                              priority=snat_idx)
                              ip_lib.sysctl(cmd, namespace=self.ns_name)
                          else:
                              self._delete_gateway_device_if_exists(ns_ipd,
                                                                    gw_ip_addr,
                                                                    snat_idx)
                              ns_ipr.rule.delete(ip=sn_port_cidr,
                                                 table=snat_idx,
                                                 priority=snat_idx)
          except Exception:
              if is_add:
                  exc = 'DVR: error adding redirection logic'
              else:
                  exc = ('DVR: snat remove failed to clear the rule '
                         'and device')
              LOG.exception(exc)
  
      def _snat_redirect_add(self, gateway, sn_port, sn_int):
          """Adds rules and routes for SNAT redirection."""
          self._snat_redirect_modify(gateway, sn_port, sn_int, is_add=True)
  
      def _snat_redirect_remove(self, gateway, sn_port, sn_int):
          """Removes rules and routes for SNAT redirection."""
          self._snat_redirect_modify(gateway, sn_port, sn_int, is_add=False)
  
      def internal_network_added(self, port):
          super(DvrLocalRouter, self).internal_network_added(port)
  
          # NOTE: The following function _set_subnet_arp_info
          # should be called to dynamically populate the arp
          # entries for the dvr services ports into the router
          # namespace. This does not have dependency on the
          # external_gateway port or the agent_mode.
          ex_gw_port = self.get_ex_gw_port()
          for subnet in port['subnets']:
              self._set_subnet_arp_info(subnet['id'])
              if ex_gw_port:
                  # Check for address_scopes here if gateway exists.
                  address_scopes_match = self._check_if_address_scopes_match(
                      port, ex_gw_port)
                  if (address_scopes_match and
                      (self.agent_conf.agent_mode in
                          [lib_constants.L3_AGENT_MODE_DVR,
                           lib_constants.L3_AGENT_MODE_DVR_SNAT])):
                      self._add_interface_routing_rule_to_router_ns(port)
                      self._add_interface_route_to_fip_ns(port)
          self._snat_redirect_add_from_port(port)
  
      def _snat_redirect_add_from_port(self, port):
          ex_gw_port = self.get_ex_gw_port()
          if not ex_gw_port:
              return
          address_scopes_match = self._check_if_address_scopes_match(
              port, ex_gw_port)
          if (address_scopes_match and
              (self.agent_conf.agent_mode in
                  [lib_constants.L3_AGENT_MODE_DVR,
                   lib_constants.L3_AGENT_MODE_DVR_SNAT])):
              return
          sn_port = self.get_snat_port_for_internal_port(port)
          if not sn_port:
              return
  
          interface_name = self.get_internal_device_name(port['id'])
          self._snat_redirect_add(sn_port, port, interface_name)
  
      def _dvr_internal_network_removed(self, port):
          # Clean up the cached arp entries related to the port subnet
          for subnet in port['subnets']:
              self._delete_arp_cache_for_internal_port(subnet)
  
          if not self.ex_gw_port:
              return
  
          # Delete DVR address_scope static route for the removed interface
          # Check for address_scopes here.
          address_scopes_match = self._check_if_address_scopes_match(
              port, self.ex_gw_port)
          if (address_scopes_match and
              (self.agent_conf.agent_mode in
                  [lib_constants.L3_AGENT_MODE_DVR,
                   lib_constants.L3_AGENT_MODE_DVR_SNAT])):
              self._delete_interface_route_in_fip_ns(port)
              self._delete_interface_routing_rule_in_router_ns(port)
              # If address scopes match there is no need to cleanup the
              # snat redirect rules, hence return here.
              return
          sn_port = self.get_snat_port_for_internal_port(port, self.snat_ports)
          if not sn_port:
              return
  
          # DVR handling code for SNAT
          interface_name = self.get_internal_device_name(port['id'])
          self._snat_redirect_remove(sn_port, port, interface_name)
  
      def internal_network_removed(self, port):
          self._dvr_internal_network_removed(port)
          super(DvrLocalRouter, self).internal_network_removed(port)
  
      def get_floating_agent_gw_interface(self, ext_net_id):
          """Filter Floating Agent GW port for the external network."""
          fip_ports = self.router.get(n_const.FLOATINGIP_AGENT_INTF_KEY, [])
          return next(
              (p for p in fip_ports if p['network_id'] == ext_net_id), None)
  
      def get_snat_external_device_interface_name(self, port_id):
          pass
  
      def get_external_device_interface_name(self, ex_gw_port):
          fip_int = self.fip_ns.get_int_device_name(self.router_id)
          if ip_lib.device_exists(fip_int, namespace=self.fip_ns.get_name()):
              return self.fip_ns.get_rtr_ext_device_name(self.router_id)
  
      def enable_snat_redirect_rules(self, ex_gw_port):
          for p in self.internal_ports:
              gateway = self.get_snat_port_for_internal_port(p)
              if not gateway:
                  continue
              address_scopes_match = self._check_if_address_scopes_match(
                  p, ex_gw_port)
              if (not address_scopes_match or
                  (self.agent_conf.agent_mode ==
                      lib_constants.L3_AGENT_MODE_DVR_NO_EXTERNAL)):
                  internal_dev = self.get_internal_device_name(p['id'])
                  self._snat_redirect_add(gateway, p, internal_dev)
  
      def disable_snat_redirect_rules(self, ex_gw_port):
          for p in self.internal_ports:
              gateway = self.get_snat_port_for_internal_port(
                  p, self.snat_ports)
              if not gateway:
                  continue
              address_scopes_match = self._check_if_address_scopes_match(
                  p, ex_gw_port)
              if (not address_scopes_match or
                  (self.agent_conf.agent_mode ==
                      lib_constants.L3_AGENT_MODE_DVR_NO_EXTERNAL)):
                  internal_dev = self.get_internal_device_name(p['id'])
                  self._snat_redirect_remove(gateway, p, internal_dev)
  
      def external_gateway_added(self, ex_gw_port, interface_name):
          # TODO(Carl) Refactor external_gateway_added/updated/removed to use
          # super class implementation where possible.  Looks like preserve_ips,
          # and ns_name are the key differences.
          cmd = ['net.ipv4.conf.all.send_redirects=0']
          ip_lib.sysctl(cmd, namespace=self.ns_name)
  
          self.enable_snat_redirect_rules(ex_gw_port)
          for port in self.get_snat_interfaces():
              for ip in port['fixed_ips']:
                  self._update_arp_entry(ip['ip_address'],
                                         port['mac_address'],
                                         ip['subnet_id'],
                                         'add')
  
      def external_gateway_updated(self, ex_gw_port, interface_name):
          pass
  
      def process_floating_ip_nat_rules(self):
          """Configure NAT rules for the router's floating IPs.
  
          Configures iptables rules for the floating ips of the given router
          """
          # Clear out all iptables rules for floating ips
          self.iptables_manager.ipv4['nat'].clear_rules_by_tag('floating_ip')
  
          floating_ips = self.get_floating_ips()
          # Loop once to ensure that floating ips are configured.
          for fip in floating_ips:
              # If floating IP is snat_bound, then the iptables rule should
              # not be installed to qrouter namespace, since the mixed snat
              # namespace may already install it.
              if fip.get(lib_constants.DVR_SNAT_BOUND):
                  continue
              # Rebuild iptables rules for the floating ip.
              for chain, rule in self.floating_forward_rules(fip):
                  self.iptables_manager.ipv4['nat'].add_rule(
                      chain, rule, tag='floating_ip')
  
          self.iptables_manager.apply()
  
      def external_gateway_removed(self, ex_gw_port, interface_name):
          # TODO(Carl) Should this be calling process_snat_dnat_for_fip?
          self.process_floating_ip_nat_rules()
          if self.fip_ns:
              to_fip_interface_name = (
                  self.get_external_device_interface_name(ex_gw_port))
              self.process_floating_ip_addresses(to_fip_interface_name)
              # Remove the router to fip namespace connection after the
              # gateway is removed.
              self.fip_ns.delete_rtr_2_fip_link(self)
              self.rtr_fip_connect = False
          # NOTE:_snat_redirect_remove should be only called when the
          # gateway is cleared and should not be called when the gateway
          # is moved or rescheduled.
          if not self.router.get('gw_port'):
              self.disable_snat_redirect_rules(ex_gw_port)
  
      def _handle_router_snat_rules(self, ex_gw_port, interface_name):
          """Configures NAT rules for Floating IPs for DVR."""
  
          self.iptables_manager.ipv4['nat'].empty_chain('POSTROUTING')
          self.iptables_manager.ipv4['nat'].empty_chain('snat')
  
          ex_gw_port = self.get_ex_gw_port()
          if not ex_gw_port:
              return
  
          ext_device_name = self.get_external_device_interface_name(ex_gw_port)
          floatingips = self.get_floating_ips()
          if not ext_device_name or not floatingips:
              # Without router to fip device, or without any floating ip,
              # the snat rules should not be added
              return
  
          # Add back the jump to float-snat
          self.iptables_manager.ipv4['nat'].add_rule('snat', '-j $float-snat')
  
          rule = self._prevent_snat_for_internal_traffic_rule(ext_device_name)
          self.iptables_manager.ipv4['nat'].add_rule(*rule)
  
      def _get_address_scope_mark(self):
          # Prepare address scope iptables rule for internal ports
          internal_ports = self.router.get(lib_constants.INTERFACE_KEY, [])
          ports_scopemark = self._get_port_devicename_scopemark(
              internal_ports, self.get_internal_device_name)
          # DVR local router will use rfp port as external port
          ext_port = self.get_ex_gw_port()
          if not ext_port:
              return ports_scopemark
  
          ext_device_name = self.get_external_device_interface_name(ext_port)
          if not ext_device_name:
              return ports_scopemark
  
          ext_scope = self._get_external_address_scope()
          ext_scope_mark = self.get_address_scope_mark_mask(ext_scope)
          ports_scopemark[lib_constants.IP_VERSION_4][ext_device_name] = (
              ext_scope_mark)
          return ports_scopemark
  
      def _check_if_floatingip_bound_to_host(self, fip):
          """Check if the floating IP is bound to this host."""
          return self.host in (fip.get('host'), fip.get('dest_host'))
  
      def process_external(self):
          if self.agent_conf.agent_mode != (
              lib_constants.L3_AGENT_MODE_DVR_NO_EXTERNAL):
              ex_gw_port = self.get_ex_gw_port()
              if ex_gw_port:
                  self.create_dvr_external_gateway_on_agent(ex_gw_port)
                  self.connect_rtr_2_fip()
          super(DvrLocalRouter, self).process_external()
  
      def _check_rtr_2_fip_connect(self):
          """Checks if the rtr to fip connect exists, if not sets to false."""
          fip_ns_name = self.fip_ns.get_name()
          if ip_lib.network_namespace_exists(fip_ns_name):
              fip_2_rtr_name = self.fip_ns.get_int_device_name(self.router_id)
              if not ip_lib.device_exists(fip_2_rtr_name, namespace=fip_ns_name):
                  self.rtr_fip_connect = False
  
      def connect_rtr_2_fip(self):
          self._check_rtr_2_fip_connect()
          if self.fip_ns.agent_gateway_port and not self.rtr_fip_connect:
              ex_gw_port = self.get_ex_gw_port()
              self.fip_ns.create_rtr_2_fip_link(self)
              self.set_address_scope_interface_routes(ex_gw_port)
              self.rtr_fip_connect = True
              self.routes_updated([], self.router['routes'])
  
      def _check_if_address_scopes_match(self, int_port, ex_gw_port):
          """Checks and returns the matching state for v4 or v6 scopes."""
          int_port_addr_scopes = int_port.get('address_scopes', {})
          ext_port_addr_scopes = ex_gw_port.get('address_scopes', {})
          key = (
              lib_constants.IP_VERSION_6 if self._port_has_ipv6_subnet(int_port)
              else lib_constants.IP_VERSION_4)
          # NOTE: DVR does not support IPv6 for the floating namespace yet, so
          # until we fix it, we probably should use the snat redirect path for
          # the ports that have IPv6 address configured.
          int_port_addr_value = int_port_addr_scopes.get(str(key))
          # If the address scope of the interface is none, then don't need
          # to compare and just return.
          if int_port_addr_value is None:
              return False
          if ((key != lib_constants.IP_VERSION_6) and
                  int_port_addr_scopes.get(str(key)) in
                  ext_port_addr_scopes.values()):
              return True
          return False
  
      def _delete_interface_route_in_fip_ns(self, router_port):
          rtr_2_fip_ip, fip_2_rtr_name = self.get_rtr_fip_ip_and_interface_name()
          fip_ns_name = self.fip_ns.get_name()
          if ip_lib.network_namespace_exists(fip_ns_name):
              device = ip_lib.IPDevice(fip_2_rtr_name, namespace=fip_ns_name)
              if not device.exists():
                  return
              for subnet in router_port['subnets']:
                  rtr_port_cidr = subnet['cidr']
                  device.route.delete_route(rtr_port_cidr, str(rtr_2_fip_ip))
  
      def _add_interface_route_to_fip_ns(self, router_port):
          rtr_2_fip_ip, fip_2_rtr_name = self.get_rtr_fip_ip_and_interface_name()
          fip_ns_name = self.fip_ns.get_name()
          if ip_lib.network_namespace_exists(fip_ns_name):
              device = ip_lib.IPDevice(fip_2_rtr_name, namespace=fip_ns_name)
              if not device.exists():
                  return
              for subnet in router_port['subnets']:
                  rtr_port_cidr = subnet['cidr']
                  device.route.add_route(rtr_port_cidr, str(rtr_2_fip_ip))
  
      def _add_interface_routing_rule_to_router_ns(self, router_port):
          ip_rule = ip_lib.IPRule(namespace=self.ns_name)
          for subnet in router_port['subnets']:
              rtr_port_cidr = subnet['cidr']
              ip_rule.rule.add(ip=rtr_port_cidr,
                               table=dvr_fip_ns.FIP_RT_TBL,
                               priority=dvr_fip_ns.FAST_PATH_EXIT_PR)
  
      def _delete_interface_routing_rule_in_router_ns(self, router_port):
          ip_rule = ip_lib.IPRule(namespace=self.ns_name)
          for subnet in router_port['subnets']:
              rtr_port_cidr = subnet['cidr']
              ip_rule.rule.delete(ip=rtr_port_cidr,
                                  table=dvr_fip_ns.FIP_RT_TBL,
                                  priority=dvr_fip_ns.FAST_PATH_EXIT_PR)
  
      def get_rtr_fip_ip_and_interface_name(self):
          """Function that returns the router to fip interface name and ip."""
          if self.rtr_fip_subnet is None:
              self.rtr_fip_subnet = self.fip_ns.local_subnets.allocate(
                  self.router_id)
          rtr_2_fip, __ = self.rtr_fip_subnet.get_pair()
          fip_2_rtr_name = self.fip_ns.get_int_device_name(self.router_id)
          return rtr_2_fip.ip, fip_2_rtr_name
  
      def set_address_scope_interface_routes(self, ex_gw_port):
          """Sets routing rules for router interfaces if addr scopes match."""
          for port in self.internal_ports:
              if self._check_if_address_scopes_match(port, ex_gw_port):
                  self._add_interface_routing_rule_to_router_ns(port)
                  self._add_interface_route_to_fip_ns(port)
  
      def create_dvr_external_gateway_on_agent(self, ex_gw_port):
          fip_agent_port = self.get_floating_agent_gw_interface(
              ex_gw_port['network_id'])
          if not fip_agent_port:
              fip_agent_port = self.agent.plugin_rpc.get_agent_gateway_port(
                  self.agent.context, ex_gw_port['network_id'])
              LOG.debug("FloatingIP agent gateway port received from the "
                        "plugin: %s", fip_agent_port)
          self.fip_ns.create_or_update_gateway_port(fip_agent_port)
  
      def update_routing_table(self, operation, route):
          # TODO(Swami): The static routes should be added to the
          # specific namespace based on the availability of the
          # network interfaces. In the case of DVR the static routes
          # for local internal router networks can be added to the
          # snat_namespace and router_namespace but should not be
          # added to the fip namespace. Likewise the static routes
          # for the external router networks should only be added to
          # the snat_namespace and fip_namespace.
          # The current code adds static routes to all namespaces in
          # order to reduce the complexity. This should be revisited
          # later.
          if self.fip_ns and self.fip_ns.agent_gateway_port:
              fip_ns_name = self.fip_ns.get_name()
              agent_gw_port = self.fip_ns.agent_gateway_port
              route_apply = self._check_if_route_applicable_to_fip_namespace(
                  route, agent_gw_port)
              if route_apply:
                  if self.rtr_fip_subnet is None:
                      self.rtr_fip_subnet = self.fip_ns.local_subnets.allocate(
                          self.router_id)
                  rtr_2_fip, fip_2_rtr = self.rtr_fip_subnet.get_pair()
                  tbl_index = self._get_snat_idx(fip_2_rtr)
                  self._update_fip_route_table_with_next_hop_routes(
                      operation, route, fip_ns_name, tbl_index)
          super(DvrLocalRouter, self).update_routing_table(operation, route)
  
      def _update_fip_route_table_with_next_hop_routes(
          self, operation, route, fip_ns_name, tbl_index):
          cmd = ['ip', 'route', operation, 'to', route['destination'],
                 'via', route['nexthop'], 'table', tbl_index]
          ip_wrapper = ip_lib.IPWrapper(namespace=fip_ns_name)
          if ip_wrapper.netns.exists(fip_ns_name):
              ip_wrapper.netns.execute(cmd, check_exit_code=False)
          else:
              LOG.debug("The FIP namespace %(ns)s does not exist for "
                        "router %(id)s",
                        {'ns': fip_ns_name, 'id': self.router_id})
  
      def _check_if_route_applicable_to_fip_namespace(
          self, route, agent_gateway_port):
          ip_cidrs = common_utils.fixed_ip_cidrs(agent_gateway_port['fixed_ips'])
          nexthop_cidr = netaddr.IPAddress(route['nexthop'])
          for gw_cidr in ip_cidrs:
              gw_subnet_cidr = netaddr.IPNetwork(gw_cidr)
              # NOTE: In the case of DVR routers apply the extra routes
              # on the FIP namespace only if it is associated with the
              # external agent gateway subnets.
              if nexthop_cidr in gw_subnet_cidr:
                  return True
          return False
  
      def get_router_cidrs(self, device):
          """As no floatingip will be set on the rfp device. Get floatingip from
          the route of fip namespace.
          """
          if not self.fip_ns:
              return set()
  
          fip_ns_name = self.fip_ns.get_name()
          fip_2_rtr_name = self.fip_ns.get_int_device_name(self.router_id)
          device = ip_lib.IPDevice(fip_2_rtr_name, namespace=fip_ns_name)
          if not device.exists():
              return set()
  
          if self.rtr_fip_subnet is None:
              self.rtr_fip_subnet = self.fip_ns.local_subnets.allocate(
                  self.router_id)
          rtr_2_fip, _fip_2_rtr = self.rtr_fip_subnet.get_pair()
          exist_routes = device.route.list_routes(
              lib_constants.IP_VERSION_4, via=str(rtr_2_fip.ip))
          return {common_utils.ip_to_cidr(route['cidr'])
                  for route in exist_routes}
  
      def process(self):
          ex_gw_port = self.get_ex_gw_port()
          if ex_gw_port:
              self.fip_ns = self.agent.get_fip_ns(ex_gw_port['network_id'])
              self.fip_ns.scan_fip_ports(self)
  
          super(DvrLocalRouter, self).process()
  