text: # vim: tabstop=4 shiftwidth=4 softtabstop=4
  #
  # Copyright 2013 VMware.  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.
  #
  
  from abc import abstractmethod
  
  from oslo.config import cfg
  
  from neutron.api import extensions
  from neutron.api.v2 import attributes
  from neutron.api.v2 import base
  from neutron import manager
  from neutron import quota
  
  
  RESOURCE_NAME = "network_gateway"
  # Use dash for alias and collection name
  EXT_ALIAS = RESOURCE_NAME.replace('_', '-')
  COLLECTION_NAME = "%ss" % EXT_ALIAS
  DEVICE_ID_ATTR = 'id'
  IFACE_NAME_ATTR = 'interface_name'
  
  # Attribute Map for Network Gateway Resource
  # TODO(salvatore-orlando): add admin state as other neutron resources
  RESOURCE_ATTRIBUTE_MAP = {
      COLLECTION_NAME: {
          'id': {'allow_post': False, 'allow_put': False,
                 'is_visible': True},
          'name': {'allow_post': True, 'allow_put': True,
                   'validate': {'type:string': None},
                   'is_visible': True, 'default': ''},
          'default': {'allow_post': False, 'allow_put': False,
                      'is_visible': True},
          'devices': {'allow_post': True, 'allow_put': False,
                      'validate': {'type:device_list': None},
                      'is_visible': True},
          'ports': {'allow_post': False, 'allow_put': False,
                    'default': [],
                    'is_visible': True},
          'tenant_id': {'allow_post': True, 'allow_put': False,
                        'validate': {'type:string': None},
                        'required_by_policy': True,
                        'is_visible': True}
      }
  }
  
  
  def _validate_device_list(data, valid_values=None):
      """Validate the list of service definitions."""
      if not data:
          # Devices must be provided
          msg = _("Cannot create a gateway with an empty device list")
          return msg
      try:
          for device in data:
              key_specs = {DEVICE_ID_ATTR:
                           {'type:regex': attributes.UUID_PATTERN,
                            'required': True},
                           IFACE_NAME_ATTR:
                           {'type:string': None,
                            'required': False}}
              err_msg = attributes._validate_dict(
                  device, key_specs=key_specs)
              if err_msg:
                  return err_msg
              unexpected_keys = [key for key in device if key not in key_specs]
              if unexpected_keys:
                  err_msg = (_("Unexpected keys found in device description:%s")
                             % ",".join(unexpected_keys))
                  return err_msg
      except TypeError:
          return (_("%s: provided data are not iterable") %
                  _validate_device_list.__name__)
  
  nw_gw_quota_opts = [
      cfg.IntOpt('quota_network_gateway',
                 default=5,
                 help=_('Number of network gateways allowed per tenant, '
                        '-1 for unlimited'))
  ]
  
  cfg.CONF.register_opts(nw_gw_quota_opts, 'QUOTAS')
  
  attributes.validators['type:device_list'] = _validate_device_list
  
  
  class Networkgw(object):
      """API extension for Layer-2 Gateway support.
  
      The Layer-2 gateway feature allows for connecting neutron networks
      with external networks at the layer-2 level. No assumption is made on
      the location of the external network, which might not even be directly
      reachable from the hosts where the VMs are deployed.
  
      This is achieved by instantiating 'network gateways', and then connecting
      Neutron network to them.
      """
  
      @classmethod
      def get_name(cls):
          return "Network Gateway"
  
      @classmethod
      def get_alias(cls):
          return EXT_ALIAS
  
      @classmethod
      def get_description(cls):
          return "Connects Neutron networks with external networks at layer 2."
  
      @classmethod
      def get_namespace(cls):
          return "http://docs.openstack.org/ext/network-gateway/api/v1.0"
  
      @classmethod
      def get_updated(cls):
          return "2014-01-01T00:00:00-00:00"
  
      @classmethod
      def get_resources(cls):
          """Returns Ext Resources."""
          plugin = manager.NeutronManager.get_plugin()
          params = RESOURCE_ATTRIBUTE_MAP.get(COLLECTION_NAME, dict())
  
          member_actions = {'connect_network': 'PUT',
                            'disconnect_network': 'PUT'}
  
          # register quotas for network gateways
          quota.QUOTAS.register_resource_by_name(RESOURCE_NAME)
          collection_name = COLLECTION_NAME.replace('_', '-')
          controller = base.create_resource(collection_name,
                                            RESOURCE_NAME,
                                            plugin, params,
                                            member_actions=member_actions)
          return [extensions.ResourceExtension(COLLECTION_NAME,
                                               controller,
                                               member_actions=member_actions)]
  
      def get_extended_resources(self, version):
          if version == "2.0":
              return RESOURCE_ATTRIBUTE_MAP
          else:
              return {}
  
  
  class NetworkGatewayPluginBase(object):
  
      @abstractmethod
      def create_network_gateway(self, context, network_gateway):
          pass
  
      @abstractmethod
      def update_network_gateway(self, context, id, network_gateway):
          pass
  
      @abstractmethod
      def get_network_gateway(self, context, id, fields=None):
          pass
  
      @abstractmethod
      def delete_network_gateway(self, context, id):
          pass
  
      @abstractmethod
      def get_network_gateways(self, context, filters=None, fields=None):
          pass
  
      @abstractmethod
      def connect_network(self, context, network_gateway_id,
                          network_mapping_info):
          pass
  
      @abstractmethod
      def disconnect_network(self, context, network_gateway_id,
                             network_mapping_info):
          pass
  