# Copyright 2012 VMware, 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.

import uuid

from oslo.config import cfg
from oslo.db import exception as db_exc
from oslo.utils import excutils
from sqlalchemy import exc as sql_exc
from sqlalchemy.orm import exc as sa_exc
import webob.exc

from neutron.api import extensions as neutron_extensions
from neutron.api.v2 import attributes as attr
from neutron.api.v2 import base
from neutron.common import constants
from neutron.common import exceptions as n_exc
from neutron.common import utils
from neutron import context as q_context
from neutron.db import agentschedulers_db
from neutron.db import allowedaddresspairs_db as addr_pair_db
from neutron.db import db_base_plugin_v2
from neutron.db import external_net_db
from neutron.db import extraroute_db
from neutron.db import l3_db
from neutron.db import l3_dvr_db
from neutron.db import l3_gwmode_db
from neutron.db import models_v2
from neutron.db import portbindings_db
from neutron.db import portsecurity_db
from neutron.db import quota_db  # noqa
from neutron.db import securitygroups_db
from neutron.extensions import allowedaddresspairs as addr_pair
from neutron.extensions import external_net as ext_net_extn
from neutron.extensions import extraroute
from neutron.extensions import l3
from neutron.extensions import multiprovidernet as mpnet
from neutron.extensions import portbindings as pbin
from neutron.extensions import portsecurity as psec
from neutron.extensions import providernet as pnet
from neutron.extensions import securitygroup as ext_sg
from neutron.i18n import _LE, _LI, _LW
from neutron.openstack.common import lockutils
from neutron.openstack.common import log as logging
from neutron.plugins.common import constants as plugin_const
from neutron.plugins import vmware
from neutron.plugins.vmware.api_client import exception as api_exc
from neutron.plugins.vmware.common import config  # noqa
from neutron.plugins.vmware.common import exceptions as nsx_exc
from neutron.plugins.vmware.common import nsx_utils
from neutron.plugins.vmware.common import securitygroups as sg_utils
from neutron.plugins.vmware.common import sync
from neutron.plugins.vmware.common import utils as c_utils
from neutron.plugins.vmware.dbexts import db as nsx_db
from neutron.plugins.vmware.dbexts import maclearning as mac_db
from neutron.plugins.vmware.dbexts import networkgw_db
from neutron.plugins.vmware.dbexts import qos_db
from neutron.plugins.vmware import dhcpmeta_modes
from neutron.plugins.vmware.extensions import maclearning as mac_ext
from neutron.plugins.vmware.extensions import networkgw
from neutron.plugins.vmware.extensions import qos
from neutron.plugins.vmware.nsxlib import l2gateway as l2gwlib
from neutron.plugins.vmware.nsxlib import queue as queuelib
from neutron.plugins.vmware.nsxlib import router as routerlib
from neutron.plugins.vmware.nsxlib import secgroup as secgrouplib
from neutron.plugins.vmware.nsxlib import switch as switchlib

LOG = logging.getLogger(__name__)

NSX_NOSNAT_RULES_ORDER = 10
NSX_FLOATINGIP_NAT_RULES_ORDER = 224
NSX_EXTGW_NAT_RULES_ORDER = 255
NSX_DEFAULT_NEXTHOP = '1.1.1.1'


class NsxPluginV2(addr_pair_db.AllowedAddressPairsMixin,
                  agentschedulers_db.DhcpAgentSchedulerDbMixin,
                  db_base_plugin_v2.NeutronDbPluginV2,
                  dhcpmeta_modes.DhcpMetadataAccess,
                  l3_dvr_db.L3_NAT_with_dvr_db_mixin,
                  external_net_db.External_net_db_mixin,
                  extraroute_db.ExtraRoute_db_mixin,
                  l3_gwmode_db.L3_NAT_db_mixin,
                  mac_db.MacLearningDbMixin,
                  networkgw_db.NetworkGatewayMixin,
                  portbindings_db.PortBindingMixin,
                  portsecurity_db.PortSecurityDbMixin,
                  qos_db.QoSDbMixin,
                  securitygroups_db.SecurityGroupDbMixin):

    supported_extension_aliases = ["allowed-address-pairs",
                                   "binding",
                                   "dvr",
                                   "ext-gw-mode",
                                   "extraroute",
                                   "mac-learning",
                                   "multi-provider",
                                   "network-gateway",
                                   "nvp-qos",
                                   "port-security",
                                   "provider",
                                   "qos-queue",
                                   "quotas",
                                   "external-net",
                                   "router",
                                   "security-group"]

    __native_bulk_support = True
    __native_pagination_support = True
    __native_sorting_support = True

    # Map nova zones to cluster for easy retrieval
    novazone_cluster_map = {}

    def __init__(self):
        super(NsxPluginV2, self).__init__()
        config.validate_config_options()
        # TODO(salv-orlando): Replace These dicts with
        # collections.defaultdict for better handling of default values
        # Routines for managing logical ports in NSX
        self.port_special_owners = [l3_db.DEVICE_OWNER_ROUTER_GW,
                                    l3_db.DEVICE_OWNER_ROUTER_INTF]
        self._port_drivers = {
            'create': {l3_db.DEVICE_OWNER_ROUTER_GW:
                       self._nsx_create_ext_gw_port,
                       l3_db.DEVICE_OWNER_FLOATINGIP:
                       self._nsx_create_fip_port,
                       l3_db.DEVICE_OWNER_ROUTER_INTF:
                       self._nsx_create_router_port,
                       networkgw_db.DEVICE_OWNER_NET_GW_INTF:
                       self._nsx_create_l2_gw_port,
                       'default': self._nsx_create_port},
            'delete': {l3_db.DEVICE_OWNER_ROUTER_GW:
                       self._nsx_delete_ext_gw_port,
                       l3_db.DEVICE_OWNER_ROUTER_INTF:
                       self._nsx_delete_router_port,
                       l3_db.DEVICE_OWNER_FLOATINGIP:
                       self._nsx_delete_fip_port,
                       networkgw_db.DEVICE_OWNER_NET_GW_INTF:
                       self._nsx_delete_port,
                       'default': self._nsx_delete_port}
        }

        neutron_extensions.append_api_extensions_path([vmware.NSX_EXT_PATH])
        self.nsx_opts = cfg.CONF.NSX
        self.nsx_sync_opts = cfg.CONF.NSX_SYNC
        self.cluster = nsx_utils.create_nsx_cluster(
            cfg.CONF,
            self.nsx_opts.concurrent_connections,
            self.nsx_opts.nsx_gen_timeout)

        self.base_binding_dict = {
            pbin.VIF_TYPE: pbin.VIF_TYPE_OVS,
            pbin.VIF_DETAILS: {
                # TODO(rkukura): Replace with new VIF security details
                pbin.CAP_PORT_FILTER:
                'security-group' in self.supported_extension_aliases}}

        self._extend_fault_map()
        self.setup_dhcpmeta_access()
        # Set this flag to false as the default gateway has not
        # been yet updated from the config file
        self._is_default_net_gw_in_sync = False
        # Create a synchronizer instance for backend sync
        self._synchronizer = sync.NsxSynchronizer(
            self.safe_reference, self.cluster,
            self.nsx_sync_opts.state_sync_interval,
            self.nsx_sync_opts.min_sync_req_delay,
            self.nsx_sync_opts.min_chunk_size,
            self.nsx_sync_opts.max_random_sync_delay)

    def _ensure_default_network_gateway(self):
        if self._is_default_net_gw_in_sync:
            return
        # Add the gw in the db as default, and unset any previous default
        def_l2_gw_uuid = self.cluster.default_l2_gw_service_uuid
        try:
            ctx = q_context.get_admin_context()
            self._unset_default_network_gateways(ctx)
            if not def_l2_gw_uuid:
                return
            try:
                def_network_gw = self._get_network_gateway(ctx,
                                                           def_l2_gw_uuid)
            except networkgw_db.GatewayNotFound:
                # Create in DB only - don't go to backend
                def_gw_data = {'id': def_l2_gw_uuid,
                               'name': 'default L2 gateway service',
                               'devices': []}
                gw_res_name = networkgw.GATEWAY_RESOURCE_NAME.replace('-', '_')
                def_network_gw = super(
                    NsxPluginV2, self).create_network_gateway(
                        ctx, {gw_res_name: def_gw_data})
            # In any case set is as default
            self._set_default_network_gateway(ctx, def_network_gw['id'])
            # Ensure this method is executed only once
            self._is_default_net_gw_in_sync = True
        except Exception:
            with excutils.save_and_reraise_exception():
                LOG.exception(_LE("Unable to process default l2 gw service: "
                                  "%s"),
                              def_l2_gw_uuid)

    def _build_ip_address_list(self, context, fixed_ips, subnet_ids=None):
        """Build ip_addresses data structure for logical router port.

        No need to perform validation on IPs - this has already been
        done in the l3_db mixin class.
        """
        ip_addresses = []
        for ip in fixed_ips:
            if not subnet_ids or (ip['subnet_id'] in subnet_ids):
                subnet = self._get_subnet(context, ip['subnet_id'])
                ip_prefix = '%s/%s' % (ip['ip_address'],
                                       subnet['cidr'].split('/')[1])
                ip_addresses.append(ip_prefix)
        return ip_addresses

    def _create_and_attach_router_port(self, cluster, context,
                                       nsx_router_id, port_data,
                                       attachment_type, attachment,
                                       attachment_vlan=None,
                                       subnet_ids=None):
        # Use a fake IP address if gateway port is not 'real'
        ip_addresses = (port_data.get('fake_ext_gw') and
                        ['0.0.0.0/31'] or
                        self._build_ip_address_list(context,
                                                    port_data['fixed_ips'],
                                                    subnet_ids))
        try:
            lrouter_port = routerlib.create_router_lport(
                cluster, nsx_router_id, port_data.get('tenant_id', 'fake'),
                port_data.get('id', 'fake'), port_data.get('name', 'fake'),
                port_data.get('admin_state_up', True), ip_addresses,
                port_data.get('mac_address'))
            LOG.debug("Created NSX router port:%s", lrouter_port['uuid'])
        except api_exc.NsxApiException:
            LOG.exception(_LE("Unable to create port on NSX logical router "
                              "%s"),
                          nsx_router_id)
            raise nsx_exc.NsxPluginException(
                err_msg=_("Unable to create logical router port for neutron "
                          "port id %(port_id)s on router %(nsx_router_id)s") %
                {'port_id': port_data.get('id'),
                 'nsx_router_id': nsx_router_id})
        self._update_router_port_attachment(cluster, context, nsx_router_id,
                                            port_data, lrouter_port['uuid'],
                                            attachment_type, attachment,
                                            attachment_vlan)
        return lrouter_port

    def _update_router_gw_info(self, context, router_id, info):
        # NOTE(salvatore-orlando): We need to worry about rollback of NSX
        # configuration in case of failures in the process
        # Ref. LP bug 1102301
        router = self._get_router(context, router_id)
        # Check whether SNAT rule update should be triggered
        # NSX also supports multiple external networks so there is also
        # the possibility that NAT rules should be replaced
        current_ext_net_id = router.gw_port_id and router.gw_port.network_id
        new_ext_net_id = info and info.get('network_id')
        # SNAT should be enabled unless info['enable_snat'] is
        # explicitly set to false
        enable_snat = new_ext_net_id and info.get('enable_snat', True)
        # Remove if ext net removed, changed, or if snat disabled
        remove_snat_rules = (current_ext_net_id and
                             new_ext_net_id != current_ext_net_id or
                             router.enable_snat and not enable_snat)
        # Add rules if snat is enabled, and if either the external network
        # changed or snat was previously disabled
        # NOTE: enable_snat == True implies new_ext_net_id != None
        add_snat_rules = (enable_snat and
                          (new_ext_net_id != current_ext_net_id or
                           not router.enable_snat))
        router = super(NsxPluginV2, self)._update_router_gw_info(
            context, router_id, info, router=router)
        # Add/Remove SNAT rules as needed
        # Create an elevated context for dealing with metadata access
        # cidrs which are created within admin context
        ctx_elevated = context.elevated()
        if remove_snat_rules or add_snat_rules:
            cidrs = self._find_router_subnets_cidrs(ctx_elevated, router_id)
        nsx_router_id = nsx_utils.get_nsx_router_id(
            context.session, self.cluster, router_id)
        if remove_snat_rules:
            # Be safe and concede NAT rules might not exist.
            # Therefore use min_num_expected=0
            for cidr in cidrs:
                routerlib.delete_nat_rules_by_match(
                    self.cluster, nsx_router_id, "SourceNatRule",
                    max_num_expected=1, min_num_expected=0,
                    raise_on_len_mismatch=False,
                    source_ip_addresses=cidr)
        if add_snat_rules:
            ip_addresses = self._build_ip_address_list(
                ctx_elevated, router.gw_port['fixed_ips'])
            # Set the SNAT rule for each subnet (only first IP)
            for cidr in cidrs:
                cidr_prefix = int(cidr.split('/')[1])
                routerlib.create_lrouter_snat_rule(
                    self.cluster, nsx_router_id,
                    ip_addresses[0].split('/')[0],
                    ip_addresses[0].split('/')[0],
                    order=NSX_EXTGW_NAT_RULES_ORDER - cidr_prefix,
                    match_criteria={'source_ip_addresses': cidr})

    def _update_router_port_attachment(self, cluster, context,
                                       nsx_router_id, port_data,
                                       nsx_router_port_id,
                                       attachment_type,
                                       attachment,
                                       attachment_vlan=None):
        if not nsx_router_port_id:
            nsx_router_port_id = self._find_router_gw_port(context, port_data)
        try:
            routerlib.plug_router_port_attachment(cluster, nsx_router_id,
                                                  nsx_router_port_id,
                                                  attachment,
                                                  attachment_type,
                                                  attachment_vlan)
            LOG.debug("Attached %(att)s to NSX router port %(port)s",
                      {'att': attachment, 'port': nsx_router_port_id})
        except api_exc.NsxApiException:
            # Must remove NSX logical port
            routerlib.delete_router_lport(cluster, nsx_router_id,
                                          nsx_router_port_id)
            LOG.exception(_LE("Unable to plug attachment in NSX logical "
                              "router port %(r_port_id)s, associated with "
                              "Neutron %(q_port_id)s"),
                          {'r_port_id': nsx_router_port_id,
                           'q_port_id': port_data.get('id')})
            raise nsx_exc.NsxPluginException(
                err_msg=(_("Unable to plug attachment in router port "
                           "%(r_port_id)s for neutron port id %(q_port_id)s "
                           "on router %(router_id)s") %
                         {'r_port_id': nsx_router_port_id,
                          'q_port_id': port_data.get('id'),
                          'router_id': nsx_router_id}))

    def _get_port_by_device_id(self, context, device_id, device_owner):
        """Retrieve ports associated with a specific device id.

        Used for retrieving all neutron ports attached to a given router.
        """
        port_qry = context.session.query(models_v2.Port)
        return port_qry.filter_by(
            device_id=device_id,
            device_owner=device_owner,).all()

    def _find_router_subnets_cidrs(self, context, router_id):
        """Retrieve subnets attached to the specified router."""
        ports = self._get_port_by_device_id(context, router_id,
                                            l3_db.DEVICE_OWNER_ROUTER_INTF)
        # No need to check for overlapping CIDRs
        cidrs = []
        for port in ports:
            for ip in port.get('fixed_ips', []):
                cidrs.append(self._get_subnet(context,
                                              ip.subnet_id).cidr)
        return cidrs

    def _nsx_find_lswitch_for_port(self, context, port_data):
        network = self._get_network(context, port_data['network_id'])
        network_bindings = nsx_db.get_network_bindings(
            context.session, port_data['network_id'])
        max_ports = self.nsx_opts.max_lp_per_overlay_ls
        allow_extra_lswitches = False
        for network_binding in network_bindings:
            if network_binding.binding_type in (c_utils.NetworkTypes.FLAT,
                                                c_utils.NetworkTypes.VLAN):
                max_ports = self.nsx_opts.max_lp_per_bridged_ls
                allow_extra_lswitches = True
                break
        try:
            return self._handle_lswitch_selection(
                context, self.cluster, network, network_bindings,
                max_ports, allow_extra_lswitches)
        except api_exc.NsxApiException:
            err_desc = _("An exception occurred while selecting logical "
                         "switch for the port")
            LOG.exception(err_desc)
            raise nsx_exc.NsxPluginException(err_msg=err_desc)

    def _nsx_create_port_helper(self, session, ls_uuid, port_data,
                                do_port_security=True):
        # Convert Neutron security groups identifiers into NSX security
        # profiles identifiers
        nsx_sec_profile_ids = [
            nsx_utils.get_nsx_security_group_id(
                session, self.cluster, neutron_sg_id) for
            neutron_sg_id in (port_data[ext_sg.SECURITYGROUPS] or [])]
        return switchlib.create_lport(self.cluster,
                                      ls_uuid,
                                      port_data['tenant_id'],
                                      port_data['id'],
                                      port_data['name'],
                                      port_data['device_id'],
                                      port_data['admin_state_up'],
                                      port_data['mac_address'],
                                      port_data['fixed_ips'],
                                      port_data[psec.PORTSECURITY],
                                      nsx_sec_profile_ids,
                                      port_data.get(qos.QUEUE),
                                      port_data.get(mac_ext.MAC_LEARNING),
                                      port_data.get(addr_pair.ADDRESS_PAIRS))

    def _handle_create_port_exception(self, context, port_id,
                                      ls_uuid, lp_uuid):
        with excutils.save_and_reraise_exception():
            # rollback nsx logical port only if it was successfully
            # created on NSX. Should this command fail the original
            # exception will be raised.
            if lp_uuid:
                # Remove orphaned port from NSX
                switchlib.delete_port(self.cluster, ls_uuid, lp_uuid)
            # rollback the neutron-nsx port mapping
            nsx_db.delete_neutron_nsx_port_mapping(context.session,
                                                   port_id)
            LOG.exception(_LE("An exception occurred while creating the "
                              "neutron port %s on the NSX plaform"), port_id)

    def _nsx_create_port(self, context, port_data):
        """Driver for creating a logical switch port on NSX platform."""
        # FIXME(salvatore-orlando): On the NSX platform we do not really have
        # external networks. So if as user tries and create a "regular" VIF
        # port on an external network we are unable to actually create.
        # However, in order to not break unit tests, we need to still create
        # the DB object and return success
        if self._network_is_external(context, port_data['network_id']):
            LOG.info(_LI("NSX plugin does not support regular VIF ports on "
                         "external networks. Port %s will be down."),
                     port_data['network_id'])
            # No need to actually update the DB state - the default is down
            return port_data
        lport = None
        selected_lswitch = None
        try:
            selected_lswitch = self._nsx_find_lswitch_for_port(context,
                                                               port_data)
            lport = self._nsx_create_port_helper(context.session,
                                                 selected_lswitch['uuid'],
                                                 port_data,
                                                 True)
            nsx_db.add_neutron_nsx_port_mapping(
                context.session, port_data['id'],
                selected_lswitch['uuid'], lport['uuid'])
            if port_data['device_owner'] not in self.port_special_owners:
                switchlib.plug_vif_interface(
                    self.cluster, selected_lswitch['uuid'],
                    lport['uuid'], "VifAttachment", port_data['id'])
            LOG.debug("_nsx_create_port completed for port %(name)s "
                      "on network %(network_id)s. The new port id is "
                      "%(id)s.", port_data)
        except (api_exc.NsxApiException, n_exc.NeutronException):
            self._handle_create_port_exception(
                context, port_data['id'],
                selected_lswitch and selected_lswitch['uuid'],
                lport and lport['uuid'])
        except db_exc.DBError as e:
            if (port_data['device_owner'] == constants.DEVICE_OWNER_DHCP and
                isinstance(e.inner_exception, sql_exc.IntegrityError)):
                LOG.warning(
                    _LW("Concurrent network deletion detected; Back-end "
                        "Port %(nsx_id)s creation to be rolled back for "
                        "Neutron port: %(neutron_id)s"),
                    {'nsx_id': lport['uuid'],
                     'neutron_id': port_data['id']})
                if selected_lswitch and lport:
                    try:
                        switchlib.delete_port(self.cluster,
                                              selected_lswitch['uuid'],
                                              lport['uuid'])
                    except n_exc.NotFound:
                        LOG.debug("NSX Port %s already gone", lport['uuid'])

    def _nsx_delete_port(self, context, port_data):
        # FIXME(salvatore-orlando): On the NSX platform we do not really have
        # external networks. So deleting regular ports from external networks
        # does not make sense. However we cannot raise as this would break
        # unit tests.
        if self._network_is_external(context, port_data['network_id']):
            LOG.info(_LI("NSX plugin does not support regular VIF ports on "
                         "external networks. Port %s will be down."),
                     port_data['network_id'])
            return
        nsx_switch_id, nsx_port_id = nsx_utils.get_nsx_switch_and_port_id(
            context.session, self.cluster, port_data['id'])
        if not nsx_port_id:
            LOG.debug("Port '%s' was already deleted on NSX platform", id)
            return
        # TODO(bgh): if this is a bridged network and the lswitch we just got
        # back will have zero ports after the delete we should garbage collect
        # the lswitch.
        try:
            switchlib.delete_port(self.cluster, nsx_switch_id, nsx_port_id)
            LOG.debug("_nsx_delete_port completed for port %(port_id)s "
                      "on network %(net_id)s",
                      {'port_id': port_data['id'],
                       'net_id': port_data['network_id']})
        except n_exc.NotFound:
            LOG.warning(_LW("Port %s not found in NSX"), port_data['id'])

    def _nsx_delete_router_port(self, context, port_data):
        # Delete logical router port
        nsx_router_id = nsx_utils.get_nsx_router_id(
            context.session, self.cluster, port_data['device_id'])
        nsx_switch_id, nsx_port_id = nsx_utils.get_nsx_switch_and_port_id(
            context.session, self.cluster, port_data['id'])
        if not nsx_port_id:
            LOG.warn(
                _LW("Neutron port %(port_id)s not found on NSX backend. "
                    "Terminating delete operation. A dangling router port "
                    "might have been left on router %(router_id)s"),
                {'port_id': port_data['id'],
                 'router_id': nsx_router_id})
            return
        try:
            routerlib.delete_peer_router_lport(self.cluster,
                                               nsx_router_id,
                                               nsx_switch_id,
                                               nsx_port_id)
        except api_exc.NsxApiException:
            # Do not raise because the issue might as well be that the
            # router has already been deleted, so there would be nothing
            # to do here
            LOG.exception(_LE("Ignoring exception as this means the peer "
                              "for port '%s' has already been deleted."),
                          nsx_port_id)

        # Delete logical switch port
        self._nsx_delete_port(context, port_data)

    def _nsx_create_router_port(self, context, port_data):
        """Driver for creating a switch port to be connected to a router."""
        # No router ports on external networks!
        if self._network_is_external(context, port_data['network_id']):
            raise nsx_exc.NsxPluginException(
                err_msg=(_("It is not allowed to create router interface "
                           "ports on external networks as '%s'") %
                         port_data['network_id']))
        ls_port = None
        selected_lswitch = None
        try:
            selected_lswitch = self._nsx_find_lswitch_for_port(
                context, port_data)
            # Do not apply port security here!
            ls_port = self._nsx_create_port_helper(
                context.session, selected_lswitch['uuid'],
                port_data, False)
            # Assuming subnet being attached is on first fixed ip
            # element in port data
            subnet_id = port_data['fixed_ips'][0]['subnet_id']
            nsx_router_id = nsx_utils.get_nsx_router_id(
                context.session, self.cluster, port_data['device_id'])
            # Create peer port on logical router
            self._create_and_attach_router_port(
                self.cluster, context, nsx_router_id, port_data,
                "PatchAttachment", ls_port['uuid'],
                subnet_ids=[subnet_id])
            nsx_db.add_neutron_nsx_port_mapping(
                context.session, port_data['id'],
                selected_lswitch['uuid'], ls_port['uuid'])
            LOG.debug("_nsx_create_router_port completed for port "
                      "%(name)s on network %(network_id)s. The new "
                      "port id is %(id)s.",
                      port_data)
        except (api_exc.NsxApiException, n_exc.NeutronException):
            self._handle_create_port_exception(
                context, port_data['id'],
                selected_lswitch and selected_lswitch['uuid'],
                ls_port and ls_port['uuid'])

    def _find_router_gw_port(self, context, port_data):
        router_id = port_data['device_id']
        if not router_id:
            raise n_exc.BadRequest(_("device_id field must be populated in "
                                   "order to create an external gateway "
                                   "port for network %s"),
                                   port_data['network_id'])
        nsx_router_id = nsx_utils.get_nsx_router_id(
            context.session, self.cluster, router_id)
        lr_port = routerlib.find_router_gw_port(context, self.cluster,
                                                nsx_router_id)
        if not lr_port:
            raise nsx_exc.NsxPluginException(
                err_msg=(_("The gateway port for the NSX router %s "
                           "was not found on the backend")
                         % nsx_router_id))
        return lr_port

    @lockutils.synchronized('vmware', 'neutron-')
    def _nsx_create_ext_gw_port(self, context, port_data):
        """Driver for creating an external gateway port on NSX platform."""
        # TODO(salvatore-orlando): Handle NSX resource
        # rollback when something goes not quite as expected
        lr_port = self._find_router_gw_port(context, port_data)
        ip_addresses = self._build_ip_address_list(context,
                                                   port_data['fixed_ips'])
        # This operation actually always updates a NSX logical port
        # instead of creating one. This is because the gateway port
        # is created at the same time as the NSX logical router, otherwise
        # the fabric status of the NSX router will be down.
        # admin_status should always be up for the gateway port
        # regardless of what the user specifies in neutron
        nsx_router_id = nsx_utils.get_nsx_router_id(
            context.session, self.cluster, port_data['device_id'])
        routerlib.update_router_lport(self.cluster,
                                      nsx_router_id,
                                      lr_port['uuid'],
                                      port_data['tenant_id'],
                                      port_data['id'],
                                      port_data['name'],
                                      True,
                                      ip_addresses)
        ext_network = self.get_network(context, port_data['network_id'])
        if ext_network.get(pnet.NETWORK_TYPE) == c_utils.NetworkTypes.L3_EXT:
            # Update attachment
            physical_network = (ext_network[pnet.PHYSICAL_NETWORK] or
                                self.cluster.default_l3_gw_service_uuid)
            self._update_router_port_attachment(
                self.cluster, context, nsx_router_id, port_data,
                lr_port['uuid'],
                "L3GatewayAttachment",
                physical_network,
                ext_network[pnet.SEGMENTATION_ID])

        LOG.debug("_nsx_create_ext_gw_port completed on external network "
                  "%(ext_net_id)s, attached to router:%(router_id)s. "
                  "NSX port id is %(nsx_port_id)s",
                  {'ext_net_id': port_data['network_id'],
                   'router_id': nsx_router_id,
                   'nsx_port_id': lr_port['uuid']})

    @lockutils.synchronized('vmware', 'neutron-')
    def _nsx_delete_ext_gw_port(self, context, port_data):
        lr_port = self._find_router_gw_port(context, port_data)
        # TODO(salvatore-orlando): Handle NSX resource
        # rollback when something goes not quite as expected
        try:
            # Delete is actually never a real delete, otherwise the NSX
            # logical router will stop working
            router_id = port_data['device_id']
            nsx_router_id = nsx_utils.get_nsx_router_id(
                context.session, self.cluster, router_id)
            routerlib.update_router_lport(self.cluster,
                                          nsx_router_id,
                                          lr_port['uuid'],
                                          port_data['tenant_id'],
                                          port_data['id'],
                                          port_data['name'],
                                          True,
                                          ['0.0.0.0/31'])
            # Reset attachment
            self._update_router_port_attachment(
                self.cluster, context, nsx_router_id, port_data,
                lr_port['uuid'],
                "L3GatewayAttachment",
                self.cluster.default_l3_gw_service_uuid)

        except api_exc.ResourceNotFound:
            raise nsx_exc.NsxPluginException(
                err_msg=_("Logical router resource %s not found "
                          "on NSX platform") % router_id)
        except api_exc.NsxApiException:
            raise nsx_exc.NsxPluginException(
                err_msg=_("Unable to update logical router"
                          "on NSX Platform"))
        LOG.debug("_nsx_delete_ext_gw_port completed on external network "
                  "%(ext_net_id)s, attached to NSX router:%(router_id)s",
                  {'ext_net_id': port_data['network_id'],
                   'router_id': nsx_router_id})

    def _nsx_create_l2_gw_port(self, context, port_data):
        """Create a switch port, and attach it to a L2 gateway attachment."""
        # FIXME(salvatore-orlando): On the NSX platform we do not really have
        # external networks. So if as user tries and create a "regular" VIF
        # port on an external network we are unable to actually create.
        # However, in order to not break unit tests, we need to still create
        # the DB object and return success
        if self._network_is_external(context, port_data['network_id']):
            LOG.info(_LI("NSX plugin does not support regular VIF ports on "
                         "external networks. Port %s will be down."),
                     port_data['network_id'])
            # No need to actually update the DB state - the default is down
            return port_data
        lport = None
        try:
            selected_lswitch = self._nsx_find_lswitch_for_port(
                context, port_data)
            lport = self._nsx_create_port_helper(
                context.session,
                selected_lswitch['uuid'],
                port_data,
                True)
            nsx_db.add_neutron_nsx_port_mapping(
                context.session, port_data['id'],
                selected_lswitch['uuid'], lport['uuid'])
            l2gwlib.plug_l2_gw_service(
                self.cluster,
                selected_lswitch['uuid'],
                lport['uuid'],
                port_data['device_id'],
                int(port_data.get('gw:segmentation_id') or 0))
        except Exception:
            with excutils.save_and_reraise_exception():
                if lport:
                    switchlib.delete_port(self.cluster,
                                          selected_lswitch['uuid'],
                                          lport['uuid'])
        LOG.debug("_nsx_create_l2_gw_port completed for port %(name)s "
                  "on network %(network_id)s. The new port id "
                  "is %(id)s.", port_data)

    def _nsx_create_fip_port(self, context, port_data):
        # As we do not create ports for floating IPs in NSX,
        # this is a no-op driver
        pass

    def _nsx_delete_fip_port(self, context, port_data):
        # As we do not create ports for floating IPs in NSX,
        # this is a no-op driver
        pass

    def _extend_fault_map(self):
        """Extends the Neutron Fault Map.

        Exceptions specific to the NSX Plugin are mapped to standard
        HTTP Exceptions.
        """
        base.FAULT_MAP.update({nsx_exc.InvalidNovaZone:
                               webob.exc.HTTPBadRequest,
                               nsx_exc.NoMorePortsException:
                               webob.exc.HTTPBadRequest,
                               nsx_exc.MaintenanceInProgress:
                               webob.exc.HTTPServiceUnavailable,
                               nsx_exc.InvalidSecurityCertificate:
                               webob.exc.HTTPBadRequest})

    def _validate_provider_create(self, context, network):
        segments = network.get(mpnet.SEGMENTS)
        if not attr.is_attr_set(segments):
            return

        mpnet.check_duplicate_segments(segments)
        for segment in segments:
            network_type = segment.get(pnet.NETWORK_TYPE)
            physical_network = segment.get(pnet.PHYSICAL_NETWORK)
            physical_network_set = attr.is_attr_set(physical_network)
            segmentation_id = segment.get(pnet.SEGMENTATION_ID)
            network_type_set = attr.is_attr_set(network_type)
            segmentation_id_set = attr.is_attr_set(segmentation_id)

            # If the physical_network_uuid isn't passed in use the default one.
            if not physical_network_set:
                physical_network = cfg.CONF.default_tz_uuid

            err_msg = None
            if not network_type_set:
                err_msg = _("%s required") % pnet.NETWORK_TYPE
            elif network_type in (c_utils.NetworkTypes.GRE,
                                  c_utils.NetworkTypes.STT,
                                  c_utils.NetworkTypes.FLAT):
                if segmentation_id_set:
                    err_msg = _("Segmentation ID cannot be specified with "
                                "flat network type")
            elif network_type == c_utils.NetworkTypes.VLAN:
                if not segmentation_id_set:
                    err_msg = _("Segmentation ID must be specified with "
                                "vlan network type")
                elif (segmentation_id_set and
                      not utils.is_valid_vlan_tag(segmentation_id)):
                    err_msg = (_("%(segmentation_id)s out of range "
                                 "(%(min_id)s through %(max_id)s)") %
                               {'segmentation_id': segmentation_id,
                                'min_id': constants.MIN_VLAN_TAG,
                                'max_id': constants.MAX_VLAN_TAG})
                else:
                    # Verify segment is not already allocated
                    bindings = (
                        nsx_db.get_network_bindings_by_vlanid_and_physical_net(
                            context.session, segmentation_id,
                            physical_network)
                    )
                    if bindings:
                        raise n_exc.VlanIdInUse(
                            vlan_id=segmentation_id,
                            physical_network=physical_network)
            elif network_type == c_utils.NetworkTypes.L3_EXT:
                if (segmentation_id_set and
                    not utils.is_valid_vlan_tag(segmentation_id)):
                    err_msg = (_("%(segmentation_id)s out of range "
                                 "(%(min_id)s through %(max_id)s)") %
                               {'segmentation_id': segmentation_id,
                                'min_id': constants.MIN_VLAN_TAG,
                                'max_id': constants.MAX_VLAN_TAG})
            else:
                err_msg = (_("%(net_type_param)s %(net_type_value)s not "
                             "supported") %
                           {'net_type_param': pnet.NETWORK_TYPE,
                            'net_type_value': network_type})
            if err_msg:
                raise n_exc.InvalidInput(error_message=err_msg)
            # TODO(salvatore-orlando): Validate tranport zone uuid
            # which should be specified in physical_network

    def _extend_network_dict_provider(self, context, network,
                                      multiprovider=None, bindings=None):
        if not bindings:
            bindings = nsx_db.get_network_bindings(context.session,
                                                   network['id'])
        if not multiprovider:
            multiprovider = nsx_db.is_multiprovider_network(context.session,
                                                            network['id'])
        # With NSX plugin 'normal' overlay networks will have no binding
        # TODO(salvatore-orlando) make sure users can specify a distinct
        # phy_uuid as 'provider network' for STT net type
        if bindings:
            if not multiprovider:
                # network came in through provider networks api
                network[pnet.NETWORK_TYPE] = bindings[0].binding_type
                network[pnet.PHYSICAL_NETWORK] = bindings[0].phy_uuid
                network[pnet.SEGMENTATION_ID] = bindings[0].vlan_id
            else:
                # network come in though multiprovider networks api
                network[mpnet.SEGMENTS] = [
                    {pnet.NETWORK_TYPE: binding.binding_type,
                     pnet.PHYSICAL_NETWORK: binding.phy_uuid,
                     pnet.SEGMENTATION_ID: binding.vlan_id}
                    for binding in bindings]

    def extend_port_dict_binding(self, port_res, port_db):
        super(NsxPluginV2, self).extend_port_dict_binding(port_res, port_db)
        port_res[pbin.VNIC_TYPE] = pbin.VNIC_NORMAL

    def _handle_lswitch_selection(self, context, cluster, network,
                                  network_bindings, max_ports,
                                  allow_extra_lswitches):
        lswitches = nsx_utils.fetch_nsx_switches(
            context.session, cluster, network.id)
        try:
            return [ls for ls in lswitches
                    if (ls['_relations']['LogicalSwitchStatus']
                        ['lport_count'] < max_ports)].pop(0)
        except IndexError:
            # Too bad, no switch available
            LOG.debug("No switch has available ports (%d checked)",
                      len(lswitches))
        if allow_extra_lswitches:
            # The 'main' logical switch is either the only one available
            # or the one where the 'multi_lswitch' tag was set
            while lswitches:
                main_ls = lswitches.pop(0)
                tag_dict = dict((x['scope'], x['tag'])
                                for x in main_ls['tags'])
                if 'multi_lswitch' in tag_dict:
                    break
            else:
                # by construction this statement is hit if there is only one
                # logical switch and the multi_lswitch tag has not been set.
                # The tag must therefore be added.
                tags = main_ls['tags']
                tags.append({'tag': 'True', 'scope': 'multi_lswitch'})
                switchlib.update_lswitch(cluster,
                                         main_ls['uuid'],
                                         main_ls['display_name'],
                                         network['tenant_id'],
                                         tags=tags)
            transport_zone_config = self._convert_to_nsx_transport_zones(
                cluster, network, bindings=network_bindings)
            selected_lswitch = switchlib.create_lswitch(
                cluster, network.id, network.tenant_id,
                "%s-ext-%s" % (network.name, len(lswitches)),
                transport_zone_config)
            # add a mapping between the neutron network and the newly
            # created logical switch
            nsx_db.add_neutron_nsx_network_mapping(
                context.session, network.id, selected_lswitch['uuid'])
            return selected_lswitch
        else:
            LOG.error(_LE("Maximum number of logical ports reached for "
                          "logical network %s"), network.id)
            raise nsx_exc.NoMorePortsException(network=network.id)

    def _convert_to_nsx_transport_zones(self, cluster, network=None,
                                        bindings=None):
        # TODO(salv-orlando): Remove this method and call nsx-utils direct
        return nsx_utils.convert_to_nsx_transport_zones(
            cluster.default_tz_uuid, network, bindings,
            default_transport_type=cfg.CONF.NSX.default_transport_type)

    def _convert_to_transport_zones_dict(self, network):
        """Converts the provider request body to multiprovider.
        Returns: True if request is multiprovider False if provider
        and None if neither.
        """
        if any(attr.is_attr_set(network.get(f))
               for f in (pnet.NETWORK_TYPE, pnet.PHYSICAL_NETWORK,
                         pnet.SEGMENTATION_ID)):
            if attr.is_attr_set(network.get(mpnet.SEGMENTS)):
                raise mpnet.SegmentsSetInConjunctionWithProviders()
            # convert to transport zone list
            network[mpnet.SEGMENTS] = [
                {pnet.NETWORK_TYPE: network[pnet.NETWORK_TYPE],
                 pnet.PHYSICAL_NETWORK: network[pnet.PHYSICAL_NETWORK],
                 pnet.SEGMENTATION_ID: network[pnet.SEGMENTATION_ID]}]
            del network[pnet.NETWORK_TYPE]
            del network[pnet.PHYSICAL_NETWORK]
            del network[pnet.SEGMENTATION_ID]
            return False
        if attr.is_attr_set(mpnet.SEGMENTS):
            return True

    def create_network(self, context, network):
        net_data = network['network']
        tenant_id = self._get_tenant_id_for_create(context, net_data)
        self._ensure_default_security_group(context, tenant_id)
        # Process the provider network extension
        provider_type = self._convert_to_transport_zones_dict(net_data)
        self._validate_provider_create(context, net_data)
        # Replace ATTR_NOT_SPECIFIED with None before sending to NSX
        for key, value in network['network'].iteritems():
            if value is attr.ATTR_NOT_SPECIFIED:
                net_data[key] = None
        # FIXME(arosen) implement admin_state_up = False in NSX
        if net_data['admin_state_up'] is False:
            LOG.warning(_LW("Network with admin_state_up=False are not yet "
                            "supported by this plugin. Ignoring setting for "
                            "network %s"), net_data.get('name', '<unknown>'))
        transport_zone_config = self._convert_to_nsx_transport_zones(
            self.cluster, net_data)
        external = net_data.get(ext_net_extn.EXTERNAL)
        # NOTE(salv-orlando): Pre-generating uuid for Neutron
        # network. This will be removed once the network create operation
        # becomes an asynchronous task
        net_data['id'] = str(uuid.uuid4())
        if (not attr.is_attr_set(external) or
            attr.is_attr_set(external) and not external):
            lswitch = switchlib.create_lswitch(
                self.cluster, net_data['id'],
                tenant_id, net_data.get('name'),
                transport_zone_config,
                shared=net_data.get(attr.SHARED))

        with context.session.begin(subtransactions=True):
            new_net = super(NsxPluginV2, self).create_network(context,
                                                              network)
            # Process port security extension
            self._process_network_port_security_create(
                context, net_data, new_net)
            # DB Operations for setting the network as external
            self._process_l3_create(context, new_net, net_data)
            # Process QoS queue extension
            net_queue_id = net_data.get(qos.QUEUE)
            if net_queue_id:
                # Raises if not found
                self.get_qos_queue(context, net_queue_id)
                self._process_network_queue_mapping(
                    context, new_net, net_queue_id)
            # Add mapping between neutron network and NSX switch
            if (not attr.is_attr_set(external) or
                attr.is_attr_set(external) and not external):
                nsx_db.add_neutron_nsx_network_mapping(
                    context.session, new_net['id'],
                    lswitch['uuid'])
            if (net_data.get(mpnet.SEGMENTS) and
                isinstance(provider_type, bool)):
                net_bindings = []
                for tz in net_data[mpnet.SEGMENTS]:
                    segmentation_id = tz.get(pnet.SEGMENTATION_ID, 0)
                    segmentation_id_set = attr.is_attr_set(segmentation_id)
                    if not segmentation_id_set:
                        segmentation_id = 0
                    net_bindings.append(nsx_db.add_network_binding(
                        context.session, new_net['id'],
                        tz.get(pnet.NETWORK_TYPE),
                        tz.get(pnet.PHYSICAL_NETWORK),
                        segmentation_id))
                if provider_type:
                    nsx_db.set_multiprovider_network(context.session,
                                                     new_net['id'])
                self._extend_network_dict_provider(context, new_net,
                                                   provider_type,
                                                   net_bindings)
        self.handle_network_dhcp_access(context, new_net,
                                        action='create_network')
        return new_net

    def delete_network(self, context, id):
        external = self._network_is_external(context, id)
        # Before removing entry from Neutron DB, retrieve NSX switch
        # identifiers for removing them from backend
        if not external:
            lswitch_ids = nsx_utils.get_nsx_switch_ids(
                context.session, self.cluster, id)
        with context.session.begin(subtransactions=True):
            self._process_l3_delete(context, id)
            nsx_db.delete_network_bindings(context.session, id)
            super(NsxPluginV2, self).delete_network(context, id)

        # Do not go to NSX for external networks
        if not external:
            try:
                switchlib.delete_networks(self.cluster, id, lswitch_ids)
            except n_exc.NotFound:
                LOG.warning(_LW("The following logical switches were not "
                                "found on the NSX backend:%s"), lswitch_ids)
        self.handle_network_dhcp_access(context, id, action='delete_network')
        LOG.debug("Delete network complete for network: %s", id)

    def get_network(self, context, id, fields=None):
        with context.session.begin(subtransactions=True):
            # goto to the plugin DB and fetch the network
            network = self._get_network(context, id)
            if (self.nsx_sync_opts.always_read_status or
                fields and 'status' in fields):
                # External networks are not backed by nsx lswitches
                if not network.external:
                    # Perform explicit state synchronization
                    self._synchronizer.synchronize_network(context, network)
            # Don't do field selection here otherwise we won't be able
            # to add provider networks fields
            net_result = self._make_network_dict(network)
            self._extend_network_dict_provider(context, net_result)
        return self._fields(net_result, fields)

    def get_networks(self, context, filters=None, fields=None,
                     sorts=None, limit=None, marker=None,
                     page_reverse=False):
        filters = filters or {}
        with context.session.begin(subtransactions=True):
            networks = (
                super(NsxPluginV2, self).get_networks(
                    context, filters, fields, sorts,
                    limit, marker, page_reverse))
            for net in networks:
                self._extend_network_dict_provider(context, net)
        return [self._fields(network, fields) for network in networks]

    def update_network(self, context, id, network):
        pnet._raise_if_updates_provider_attributes(network['network'])
        if network["network"].get("admin_state_up") is False:
            raise NotImplementedError(_("admin_state_up=False networks "
                                        "are not supported."))
        with context.session.begin(subtransactions=True):
            net = super(NsxPluginV2, self).update_network(context, id, network)
            if psec.PORTSECURITY in network['network']:
                self._process_network_port_security_update(
                    context, network['network'], net)
            net_queue_id = network['network'].get(qos.QUEUE)
            if net_queue_id:
                self._delete_network_queue_mapping(context, id)
                self._process_network_queue_mapping(context, net, net_queue_id)
            self._process_l3_update(context, net, network['network'])
            self._extend_network_dict_provider(context, net)
        # If provided, update port name on backend; treat backend failures as
        # not critical (log error, but do not raise)
        if 'name' in network['network']:
            # in case of chained switches update name only for the first one
            nsx_switch_ids = nsx_utils.get_nsx_switch_ids(
                context.session, self.cluster, id)
            if not nsx_switch_ids or len(nsx_switch_ids) < 1:
                LOG.warn(_LW("Unable to find NSX mappings for neutron "
                             "network:%s"), id)
            try:
                switchlib.update_lswitch(self.cluster,
                                         nsx_switch_ids[0],
                                         network['network']['name'])
            except api_exc.NsxApiException as e:
                LOG.warn(_LW("Logical switch update on NSX backend failed. "
                             "Neutron network id:%(net_id)s; "
                             "NSX lswitch id:%(lswitch_id)s;"
                             "Error:%(error)s"),
                         {'net_id': id, 'lswitch_id': nsx_switch_ids[0],
                          'error': e})

        return net

    def create_port(self, context, port):
        # If PORTSECURITY is not the default value ATTR_NOT_SPECIFIED
        # then we pass the port to the policy engine. The reason why we don't
        # pass the value to the policy engine when the port is
        # ATTR_NOT_SPECIFIED is for the case where a port is created on a
        # shared network that is not owned by the tenant.
        port_data = port['port']
        # Set port status as 'DOWN'. This will be updated by backend sync.
        port_data['status'] = constants.PORT_STATUS_DOWN
        with context.session.begin(subtransactions=True):
            # First we allocate port in neutron database
            neutron_db = super(NsxPluginV2, self).create_port(context, port)
            neutron_port_id = neutron_db['id']
            # Update fields obtained from neutron db (eg: MAC address)
            port["port"].update(neutron_db)
            self.handle_port_metadata_access(context, neutron_db)
            # port security extension checks
            (port_security, has_ip) = self._determine_port_security_and_has_ip(
                context, port_data)
            port_data[psec.PORTSECURITY] = port_security
            self._process_port_port_security_create(
                context, port_data, neutron_db)
            # allowed address pair checks
            if attr.is_attr_set(port_data.get(addr_pair.ADDRESS_PAIRS)):
                if not port_security:
                    raise addr_pair.AddressPairAndPortSecurityRequired()
                else:
                    self._process_create_allowed_address_pairs(
                        context, neutron_db,
                        port_data[addr_pair.ADDRESS_PAIRS])
            else:
                # remove ATTR_NOT_SPECIFIED
                port_data[addr_pair.ADDRESS_PAIRS] = []

            # security group extension checks
            if port_security and has_ip:
                self._ensure_default_security_group_on_port(context, port)
            elif attr.is_attr_set(port_data.get(ext_sg.SECURITYGROUPS)):
                raise psec.PortSecurityAndIPRequiredForSecurityGroups()
            port_data[ext_sg.SECURITYGROUPS] = (
                self._get_security_groups_on_port(context, port))
            self._process_port_create_security_group(
                context, port_data, port_data[ext_sg.SECURITYGROUPS])
            # QoS extension checks
            port_queue_id = self._check_for_queue_and_create(
                context, port_data)
            self._process_port_queue_mapping(
                context, port_data, port_queue_id)
            if (isinstance(port_data.get(mac_ext.MAC_LEARNING), bool)):
                self._create_mac_learning_state(context, port_data)
            elif mac_ext.MAC_LEARNING in port_data:
                port_data.pop(mac_ext.MAC_LEARNING)
            self._process_portbindings_create_and_update(context,
                                                         port['port'],
                                                         port_data)
            # For some reason the port bindings DB mixin does not handle
            # the VNIC_TYPE attribute, which is required by nova for
            # setting up VIFs.
            context.session.flush()
            port_data[pbin.VNIC_TYPE] = pbin.VNIC_NORMAL

        # DB Operation is complete, perform NSX operation
        try:
            port_data = port['port'].copy()
            port_create_func = self._port_drivers['create'].get(
                port_data['device_owner'],
                self._port_drivers['create']['default'])
            port_create_func(context, port_data)
            LOG.debug("port created on NSX backend for tenant "
                      "%(tenant_id)s: (%(id)s)", port_data)
        except n_exc.NotFound:
            LOG.warning(_LW("Logical switch for network %s was not "
                            "found in NSX."), port_data['network_id'])
            # Put port in error on neutron DB
            with context.session.begin(subtransactions=True):
                port = self._get_port(context, neutron_port_id)
                port_data['status'] = constants.PORT_STATUS_ERROR
                port['status'] = port_data['status']
                context.session.add(port)
        except Exception:
            # Port must be removed from neutron DB
            with excutils.save_and_reraise_exception():
                LOG.error(_LE("Unable to create port or set port "
                              "attachment in NSX."))
                with context.session.begin(subtransactions=True):
                    self._delete_port(context, neutron_port_id)

        self.handle_port_dhcp_access(context, port_data, action='create_port')
        return port_data

    def update_port(self, context, id, port):
        delete_security_groups = self._check_update_deletes_security_groups(
            port)
        has_security_groups = self._check_update_has_security_groups(port)
        delete_addr_pairs = self._check_update_deletes_allowed_address_pairs(
            port)
        has_addr_pairs = self._check_update_has_allowed_address_pairs(port)

        with context.session.begin(subtransactions=True):
            ret_port = super(NsxPluginV2, self).update_port(
                context, id, port)
            # Save current mac learning state to check whether it's
            # being updated or not
            old_mac_learning_state = ret_port.get(mac_ext.MAC_LEARNING)
            # copy values over - except fixed_ips as
            # they've already been processed
            port['port'].pop('fixed_ips', None)
            ret_port.update(port['port'])
            tenant_id = self._get_tenant_id_for_create(context, ret_port)

            # populate port_security setting
            if psec.PORTSECURITY not in port['port']:
                ret_port[psec.PORTSECURITY] = self._get_port_security_binding(
                    context, id)
            has_ip = self._ip_on_port(ret_port)
            # validate port security and allowed address pairs
            if not ret_port[psec.PORTSECURITY]:
                #  has address pairs in request
                if has_addr_pairs:
                    raise addr_pair.AddressPairAndPortSecurityRequired()
                elif not delete_addr_pairs:
                    # check if address pairs are in db
                    ret_port[addr_pair.ADDRESS_PAIRS] = (
                        self.get_allowed_address_pairs(context, id))
                    if ret_port[addr_pair.ADDRESS_PAIRS]:
                        raise addr_pair.AddressPairAndPortSecurityRequired()

            if (delete_addr_pairs or has_addr_pairs):
                # delete address pairs and read them in
                self._delete_allowed_address_pairs(context, id)
                self._process_create_allowed_address_pairs(
                    context, ret_port, ret_port[addr_pair.ADDRESS_PAIRS])
            # checks if security groups were updated adding/modifying
            # security groups, port security is set and port has ip
            if not (has_ip and ret_port[psec.PORTSECURITY]):
                if has_security_groups:
                    raise psec.PortSecurityAndIPRequiredForSecurityGroups()
                # Update did not have security groups passed in. Check
                # that port does not have any security groups already on it.
                filters = {'port_id': [id]}
                security_groups = (
                    super(NsxPluginV2, self)._get_port_security_group_bindings(
                        context, filters)
                )
                if security_groups and not delete_security_groups:
                    raise psec.PortSecurityPortHasSecurityGroup()

            if (delete_security_groups or has_security_groups):
                # delete the port binding and read it with the new rules.
                self._delete_port_security_group_bindings(context, id)
                sgids = self._get_security_groups_on_port(context, port)
                self._process_port_create_security_group(context, ret_port,
                                                         sgids)

            if psec.PORTSECURITY in port['port']:
                self._process_port_port_security_update(
                    context, port['port'], ret_port)

            port_queue_id = self._check_for_queue_and_create(
                context, ret_port)
            # Populate the mac learning attribute
            new_mac_learning_state = port['port'].get(mac_ext.MAC_LEARNING)
            if (new_mac_learning_state is not None and
                old_mac_learning_state != new_mac_learning_state):
                self._update_mac_learning_state(context, id,
                                                new_mac_learning_state)
                ret_port[mac_ext.MAC_LEARNING] = new_mac_learning_state
            self._delete_port_queue_mapping(context, ret_port['id'])
            self._process_port_queue_mapping(context, ret_port,
                                             port_queue_id)
            LOG.debug("Updating port: %s", port)
            nsx_switch_id, nsx_port_id = nsx_utils.get_nsx_switch_and_port_id(
                context.session, self.cluster, id)
            # Convert Neutron security groups identifiers into NSX security
            # profiles identifiers
            nsx_sec_profile_ids = [
                nsx_utils.get_nsx_security_group_id(
                    context.session, self.cluster, neutron_sg_id) for
                neutron_sg_id in (ret_port[ext_sg.SECURITYGROUPS] or [])]

            if nsx_port_id:
                try:
                    switchlib.update_port(
                        self.cluster, nsx_switch_id, nsx_port_id,
                        id, tenant_id,
                        ret_port['name'],
                        ret_port['device_id'],
                        ret_port['admin_state_up'],
                        ret_port['mac_address'],
                        ret_port['fixed_ips'],
                        ret_port[psec.PORTSECURITY],
                        nsx_sec_profile_ids,
                        ret_port[qos.QUEUE],
                        ret_port.get(mac_ext.MAC_LEARNING),
                        ret_port.get(addr_pair.ADDRESS_PAIRS))

                    # Update the port status from nsx. If we fail here hide it
                    # since the port was successfully updated but we were not
                    # able to retrieve the status.
                    ret_port['status'] = switchlib.get_port_status(
                        self.cluster, nsx_switch_id,
                        nsx_port_id)
                # FIXME(arosen) improve exception handling.
                except Exception:
                    ret_port['status'] = constants.PORT_STATUS_ERROR
                    LOG.exception(_LE("Unable to update port id: %s."),
                                  nsx_port_id)

            # If nsx_port_id is not in database or in nsx put in error state.
            else:
                ret_port['status'] = constants.PORT_STATUS_ERROR

            self._process_portbindings_create_and_update(context,
                                                         port['port'],
                                                         ret_port)
        return ret_port

    def delete_port(self, context, id, l3_port_check=True,
                    nw_gw_port_check=True):
        """Deletes a port on a specified Virtual Network.

        If the port contains a remote interface attachment, the remote
        interface is first un-plugged and then the port is deleted.

        :returns: None
        :raises: exception.PortInUse
        :raises: exception.PortNotFound
        :raises: exception.NetworkNotFound
        """
        # if needed, check to see if this is a port owned by
        # a l3 router.  If so, we should prevent deletion here
        if l3_port_check:
            self.prevent_l3_port_deletion(context, id)
        neutron_db_port = self.get_port(context, id)
        # Perform the same check for ports owned by layer-2 gateways
        if nw_gw_port_check:
            self.prevent_network_gateway_port_deletion(context,
                                                       neutron_db_port)
        port_delete_func = self._port_drivers['delete'].get(
            neutron_db_port['device_owner'],
            self._port_drivers['delete']['default'])

        port_delete_func(context, neutron_db_port)
        self.disassociate_floatingips(context, id)
        with context.session.begin(subtransactions=True):
            queue = self._get_port_queue_bindings(context, {'port_id': [id]})
            # metadata_dhcp_host_route
            self.handle_port_metadata_access(
                context, neutron_db_port, is_delete=True)
            super(NsxPluginV2, self).delete_port(context, id)
            # Delete qos queue if possible
            if queue:
                self.delete_qos_queue(context, queue[0]['queue_id'], False)
        self.handle_port_dhcp_access(
            context, neutron_db_port, action='delete_port')

    def get_port(self, context, id, fields=None):
        with context.session.begin(subtransactions=True):
            if (self.nsx_sync_opts.always_read_status or
                fields and 'status' in fields):
                # Perform explicit state synchronization
                db_port = self._get_port(context, id)
                self._synchronizer.synchronize_port(
                    context, db_port)
                return self._make_port_dict(db_port, fields)
            else:
                return super(NsxPluginV2, self).get_port(context, id, fields)

    def get_router(self, context, id, fields=None):
        if (self.nsx_sync_opts.always_read_status or
            fields and 'status' in fields):
            db_router = self._get_router(context, id)
            # Perform explicit state synchronization
            self._synchronizer.synchronize_router(
                context, db_router)
            return self._make_router_dict(db_router, fields)
        else:
            return super(NsxPluginV2, self).get_router(context, id, fields)

    def _create_lrouter(self, context, router, nexthop):
        tenant_id = self._get_tenant_id_for_create(context, router)
        distributed = router.get('distributed')
        try:
            lrouter = routerlib.create_lrouter(
                self.cluster, router['id'],
                tenant_id, router['name'], nexthop,
                distributed=attr.is_attr_set(distributed) and distributed)
        except nsx_exc.InvalidVersion:
            msg = _("Cannot create a distributed router with the NSX "
                    "platform currently in execution. Please, try "
                    "without specifying the 'distributed' attribute.")
            LOG.exception(msg)
            raise n_exc.BadRequest(resource='router', msg=msg)
        except api_exc.NsxApiException:
            err_msg = _("Unable to create logical router on NSX Platform")
            LOG.exception(err_msg)
            raise nsx_exc.NsxPluginException(err_msg=err_msg)

        # Create the port here - and update it later if we have gw_info
        try:
            self._create_and_attach_router_port(
                self.cluster, context, lrouter['uuid'], {'fake_ext_gw': True},
                "L3GatewayAttachment",
                self.cluster.default_l3_gw_service_uuid)
        except nsx_exc.NsxPluginException:
            LOG.exception(_LE("Unable to create L3GW port on logical router "
                              "%(router_uuid)s. Verify Default Layer-3 "
                              "Gateway service %(def_l3_gw_svc)s id is "
                              "correct"),
                          {'router_uuid': lrouter['uuid'],
                           'def_l3_gw_svc':
                           self.cluster.default_l3_gw_service_uuid})
            # Try and remove logical router from NSX
            routerlib.delete_lrouter(self.cluster, lrouter['uuid'])
            # Return user a 500 with an apter message
            raise nsx_exc.NsxPluginException(
                err_msg=(_("Unable to create router %s on NSX backend") %
                         router['id']))
        lrouter['status'] = plugin_const.ACTIVE
        return lrouter

    def create_router(self, context, router):
        # NOTE(salvatore-orlando): We completely override this method in
        # order to be able to use the NSX ID as Neutron ID
        # TODO(salvatore-orlando): Propose upstream patch for allowing
        # 3rd parties to specify IDs as we do with l2 plugin
        r = router['router']
        has_gw_info = False
        tenant_id = self._get_tenant_id_for_create(context, r)
        # default value to set - nsx wants it (even if we don't have it)
        nexthop = NSX_DEFAULT_NEXTHOP
        # if external gateway info are set, then configure nexthop to
        # default external gateway
        if 'external_gateway_info' in r and r.get('external_gateway_info'):
            has_gw_info = True
            gw_info = r['external_gateway_info']
            del r['external_gateway_info']
            # The following DB read will be performed again when updating
            # gateway info. This is not great, but still better than
            # creating NSX router here and updating it later
            network_id = (gw_info.get('network_id', None) if gw_info
                          else None)
            if network_id:
                ext_net = self._get_network(context, network_id)
                if not ext_net.external:
                    msg = (_("Network '%s' is not a valid external "
                             "network") % network_id)
                    raise n_exc.BadRequest(resource='router', msg=msg)
                if ext_net.subnets:
                    ext_subnet = ext_net.subnets[0]
                    nexthop = ext_subnet.gateway_ip
        # NOTE(salv-orlando): Pre-generating uuid for Neutron
        # router. This will be removed once the router create operation
        # becomes an asynchronous task
        neutron_router_id = str(uuid.uuid4())
        r['id'] = neutron_router_id
        lrouter = self._create_lrouter(context, r, nexthop)
        # Update 'distributed' with value returned from NSX
        # This will be useful for setting the value if the API request
        # did not specify any value for the 'distributed' attribute
        # Platforms older than 3.x do not support the attribute
        r['distributed'] = lrouter.get('distributed', False)
        # TODO(salv-orlando): Deal with backend object removal in case
        # of db failures
        with context.session.begin(subtransactions=True):
            # Transaction nesting is needed to avoid foreign key violations
            # when processing the distributed router binding
            with context.session.begin(subtransactions=True):
                router_db = l3_db.Router(id=neutron_router_id,
                                         tenant_id=tenant_id,
                                         name=r['name'],
                                         admin_state_up=r['admin_state_up'],
                                         status=lrouter['status'])
                context.session.add(router_db)
                self._process_extra_attr_router_create(context, router_db, r)
                # Ensure neutron router is moved into the transaction's buffer
                context.session.flush()
                # Add mapping between neutron and nsx identifiers
                nsx_db.add_neutron_nsx_router_mapping(
                    context.session, router_db['id'], lrouter['uuid'])

        if has_gw_info:
            # NOTE(salv-orlando): This operation has been moved out of the
            # database transaction since it performs several NSX queries,
            # ithis ncreasing the risk of deadlocks between eventlet and
            # sqlalchemy operations.
            # Set external gateway and remove router in case of failure
            try:
                self._update_router_gw_info(context, router_db['id'], gw_info)
            except (n_exc.NeutronException, api_exc.NsxApiException):
                with excutils.save_and_reraise_exception():
                    # As setting gateway failed, the router must be deleted
                    # in order to ensure atomicity
                    router_id = router_db['id']
                    LOG.warn(_LW("Failed to set gateway info for router being "
                                 "created:%s - removing router"), router_id)
                    self.delete_router(context, router_id)
                    LOG.info(_LI("Create router failed while setting external "
                                 "gateway. Router:%s has been removed from "
                                 "DB and backend"),
                             router_id)
        return self._make_router_dict(router_db)

    def _update_lrouter(self, context, router_id, name, nexthop, routes=None):
        nsx_router_id = nsx_utils.get_nsx_router_id(
            context.session, self.cluster, router_id)
        return routerlib.update_lrouter(
            self.cluster, nsx_router_id, name,
            nexthop, routes=routes)

    def _update_lrouter_routes(self, context, router_id, routes):
        nsx_router_id = nsx_utils.get_nsx_router_id(
            context.session, self.cluster, router_id)
        routerlib.update_explicit_routes_lrouter(
            self.cluster, nsx_router_id, routes)

    def update_router(self, context, router_id, router):
        # Either nexthop is updated or should be kept as it was before
        r = router['router']
        nexthop = None
        if 'external_gateway_info' in r and r.get('external_gateway_info'):
            gw_info = r['external_gateway_info']
            # The following DB read will be performed again when updating
            # gateway info. This is not great, but still better than
            # creating NSX router here and updating it later
            network_id = (gw_info.get('network_id', None) if gw_info
                          else None)
            if network_id:
                ext_net = self._get_network(context, network_id)
                if not ext_net.external:
                    msg = (_("Network '%s' is not a valid external "
                             "network") % network_id)
                    raise n_exc.BadRequest(resource='router', msg=msg)
                if ext_net.subnets:
                    ext_subnet = ext_net.subnets[0]
                    nexthop = ext_subnet.gateway_ip
        try:
            for route in r.get('routes', []):
                if route['destination'] == '0.0.0.0/0':
                    msg = _("'routes' cannot contain route '0.0.0.0/0', "
                            "this must be updated through the default "
                            "gateway attribute")
                    raise n_exc.BadRequest(resource='router', msg=msg)
            previous_routes = self._update_lrouter(
                context, router_id, r.get('name'),
                nexthop, routes=r.get('routes'))
        # NOTE(salv-orlando): The exception handling below is not correct, but
        # unfortunately nsxlib raises a neutron notfound exception when an
        # object is not found in the underlying backend
        except n_exc.NotFound:
            # Put the router in ERROR status
            with context.session.begin(subtransactions=True):
                router_db = self._get_router(context, router_id)
                router_db['status'] = constants.NET_STATUS_ERROR
            raise nsx_exc.NsxPluginException(
                err_msg=_("Logical router %s not found "
                          "on NSX Platform") % router_id)
        except api_exc.NsxApiException:
            raise nsx_exc.NsxPluginException(
                err_msg=_("Unable to update logical router on NSX Platform"))
        except nsx_exc.InvalidVersion:
            msg = _("Request cannot contain 'routes' with the NSX "
                    "platform currently in execution. Please, try "
                    "without specifying the static routes.")
            LOG.exception(msg)
            raise n_exc.BadRequest(resource='router', msg=msg)
        try:
            return super(NsxPluginV2, self).update_router(context,
                                                          router_id, router)
        except (extraroute.InvalidRoutes,
                extraroute.RouterInterfaceInUseByRoute,
                extraroute.RoutesExhausted):
            with excutils.save_and_reraise_exception():
                # revert changes made to NSX
                self._update_lrouter_routes(
                    context, router_id, previous_routes)

    def _delete_lrouter(self, context, router_id, nsx_router_id):
        # The neutron router id (router_id) is ignored in this routine,
        # but used in plugins deriving from this one
        routerlib.delete_lrouter(self.cluster, nsx_router_id)

    def delete_router(self, context, router_id):
        with context.session.begin(subtransactions=True):
            # TODO(salv-orlando): This call should have no effect on delete
            # router, but if it does, it should not happen within a
            # transaction, and it should be restored on rollback
            self.handle_router_metadata_access(
                context, router_id, interface=None)
            # Pre-delete checks
            # NOTE(salv-orlando): These checks will be repeated anyway when
            # calling the superclass. This is wasteful, but is the simplest
            # way of ensuring a consistent removal of the router both in
            # the neutron Database and in the NSX backend.
            # TODO(salv-orlando): split pre-delete checks and actual
            # deletion in superclass.

            # Ensure that the router is not used
            fips = self.get_floatingips_count(
                context.elevated(), filters={'router_id': [router_id]})
            if fips:
                raise l3.RouterInUse(router_id=router_id)

            device_filter = {'device_id': [router_id],
                             'device_owner': [l3_db.DEVICE_OWNER_ROUTER_INTF]}
            ports = self._core_plugin.get_ports_count(context.elevated(),
                                                      filters=device_filter)
            if ports:
                raise l3.RouterInUse(router_id=router_id)

        nsx_router_id = nsx_utils.get_nsx_router_id(
            context.session, self.cluster, router_id)
        # It is safe to remove the router from the database, so remove it
        # from the backend
        try:
            self._delete_lrouter(context, router_id, nsx_router_id)
        except n_exc.NotFound:
            # This is not a fatal error, but needs to be logged
            LOG.warning(_LW("Logical router '%s' not found "
                            "on NSX Platform"), router_id)
        except api_exc.NsxApiException:
            raise nsx_exc.NsxPluginException(
                err_msg=(_("Unable to delete logical router '%s' "
                           "on NSX Platform") % nsx_router_id))
        # Remove the NSX mapping first in order to ensure a mapping to
        # a non-existent NSX router is not left in the DB in case of
        # failure while removing the router from the neutron DB
        try:
            nsx_db.delete_neutron_nsx_router_mapping(
                context.session, router_id)
        except db_exc.DBError as d_exc:
            # Do not make this error fatal
            LOG.warn(_LW("Unable to remove NSX mapping for Neutron router "
                         "%(router_id)s because of the following exception:"
                         "%(d_exc)s"), {'router_id': router_id,
                                        'd_exc': str(d_exc)})
        # Perform the actual delete on the Neutron DB
        super(NsxPluginV2, self).delete_router(context, router_id)

    def _add_subnet_snat_rule(self, context, router, subnet):
        gw_port = router.gw_port
        if gw_port and router.enable_snat:
            # There is a change gw_port might have multiple IPs
            # In that case we will consider only the first one
            if gw_port.get('fixed_ips'):
                snat_ip = gw_port['fixed_ips'][0]['ip_address']
                cidr_prefix = int(subnet['cidr'].split('/')[1])
                nsx_router_id = nsx_utils.get_nsx_router_id(
                    context.session, self.cluster, router['id'])
                routerlib.create_lrouter_snat_rule(
                    self.cluster, nsx_router_id, snat_ip, snat_ip,
                    order=NSX_EXTGW_NAT_RULES_ORDER - cidr_prefix,
                    match_criteria={'source_ip_addresses': subnet['cidr']})

    def _delete_subnet_snat_rule(self, context, router, subnet):
        # Remove SNAT rule if external gateway is configured
        if router.gw_port:
            nsx_router_id = nsx_utils.get_nsx_router_id(
                context.session, self.cluster, router['id'])
            routerlib.delete_nat_rules_by_match(
                self.cluster, nsx_router_id, "SourceNatRule",
                max_num_expected=1, min_num_expected=1,
                raise_on_len_mismatch=False,
                source_ip_addresses=subnet['cidr'])

    def add_router_interface(self, context, router_id, interface_info):
        # When adding interface by port_id we need to create the
        # peer port on the nsx logical router in this routine
        port_id = interface_info.get('port_id')
        router_iface_info = super(NsxPluginV2, self).add_router_interface(
            context, router_id, interface_info)
        # router_iface_info will always have a subnet_id attribute
        subnet_id = router_iface_info['subnet_id']
        nsx_router_id = nsx_utils.get_nsx_router_id(
            context.session, self.cluster, router_id)
        if port_id:
            port_data = self.get_port(context, port_id)
            # If security groups are present we need to remove them as
            # this is a router port and disable port security.
            if port_data['security_groups']:
                self.update_port(context, port_id,
                                 {'port': {'security_groups': [],
                                           psec.PORTSECURITY: False}})
            nsx_switch_id, nsx_port_id = nsx_utils.get_nsx_switch_and_port_id(
                context.session, self.cluster, port_id)
            # Unplug current attachment from lswitch port
            switchlib.plug_vif_interface(self.cluster, nsx_switch_id,
                                         nsx_port_id, "NoAttachment")
            # Create logical router port and plug patch attachment
            self._create_and_attach_router_port(
                self.cluster, context, nsx_router_id, port_data,
                "PatchAttachment", nsx_port_id, subnet_ids=[subnet_id])
        subnet = self._get_subnet(context, subnet_id)
        # If there is an external gateway we need to configure the SNAT rule.
        # Fetch router from DB
        router = self._get_router(context, router_id)
        self._add_subnet_snat_rule(context, router, subnet)
        routerlib.create_lrouter_nosnat_rule(
            self.cluster, nsx_router_id,
            order=NSX_NOSNAT_RULES_ORDER,
            match_criteria={'destination_ip_addresses': subnet['cidr']})

        # Ensure the NSX logical router has a connection to a 'metadata access'
        # network (with a proxy listening on its DHCP port), by creating it
        # if needed.
        self.handle_router_metadata_access(
            context, router_id, interface=router_iface_info)
        LOG.debug("Add_router_interface completed for subnet:%(subnet_id)s "
                  "and router:%(router_id)s",
                  {'subnet_id': subnet_id, 'router_id': router_id})
        return router_iface_info

    def remove_router_interface(self, context, router_id, interface_info):
        # The code below is duplicated from base class, but comes handy
        # as we need to retrieve the router port id before removing the port
        subnet = None
        subnet_id = None
        if 'port_id' in interface_info:
            port_id = interface_info['port_id']
            # find subnet_id - it is need for removing the SNAT rule
            port = self._get_port(context, port_id)
            if port.get('fixed_ips'):
                subnet_id = port['fixed_ips'][0]['subnet_id']
            if not (port['device_owner'] == l3_db.DEVICE_OWNER_ROUTER_INTF and
                    port['device_id'] == router_id):
                raise l3.RouterInterfaceNotFound(router_id=router_id,
                                                 port_id=port_id)
        elif 'subnet_id' in interface_info:
            subnet_id = interface_info['subnet_id']
            subnet = self._get_subnet(context, subnet_id)
            rport_qry = context.session.query(models_v2.Port)
            ports = rport_qry.filter_by(
                device_id=router_id,
                device_owner=l3_db.DEVICE_OWNER_ROUTER_INTF,
                network_id=subnet['network_id'])
            for p in ports:
                if p['fixed_ips'][0]['subnet_id'] == subnet_id:
                    port_id = p['id']
                    break
            else:
                raise l3.RouterInterfaceNotFoundForSubnet(router_id=router_id,
                                                          subnet_id=subnet_id)
        # Finally remove the data from the Neutron DB
        # This will also destroy the port on the logical switch
        info = super(NsxPluginV2, self).remove_router_interface(
            context, router_id, interface_info)

        try:
            # Ensure the connection to the 'metadata access network'
            # is removed  (with the network) if this the last subnet
            # on the router
            self.handle_router_metadata_access(
                context, router_id, interface=info)
            if not subnet:
                subnet = self._get_subnet(context, subnet_id)
            router = self._get_router(context, router_id)
            # If router is enabled_snat = False there are no snat rules to
            # delete.
            if router.enable_snat:
                self._delete_subnet_snat_rule(context, router, subnet)
            # Relax the minimum expected number as the nosnat rules
            # do not exist in 2.x deployments
            nsx_router_id = nsx_utils.get_nsx_router_id(
                context.session, self.cluster, router_id)
            routerlib.delete_nat_rules_by_match(
                self.cluster, nsx_router_id, "NoSourceNatRule",
                max_num_expected=1, min_num_expected=0,
                raise_on_len_mismatch=False,
                destination_ip_addresses=subnet['cidr'])
        except n_exc.NotFound:
            LOG.error(_LE("Logical router resource %s not found "
                          "on NSX platform"), router_id)
        except api_exc.NsxApiException:
            raise nsx_exc.NsxPluginException(
                err_msg=(_("Unable to update logical router"
                           "on NSX Platform")))
        return info

    def _retrieve_and_delete_nat_rules(self, context, floating_ip_address,
                                       internal_ip, nsx_router_id,
                                       min_num_rules_expected=0):
        """Finds and removes NAT rules from a NSX router."""
        # NOTE(salv-orlando): The context parameter is ignored in this method
        # but used by derived classes
        try:
            # Remove DNAT rule for the floating IP
            routerlib.delete_nat_rules_by_match(
                self.cluster, nsx_router_id, "DestinationNatRule",
                max_num_expected=1,
                min_num_expected=min_num_rules_expected,
                destination_ip_addresses=floating_ip_address)

            # Remove SNAT rules for the floating IP
            routerlib.delete_nat_rules_by_match(
                self.cluster, nsx_router_id, "SourceNatRule",
                max_num_expected=1,
                min_num_expected=min_num_rules_expected,
                source_ip_addresses=internal_ip)
            routerlib.delete_nat_rules_by_match(
                self.cluster, nsx_router_id, "SourceNatRule",
                max_num_expected=1,
                min_num_expected=min_num_rules_expected,
                destination_ip_addresses=internal_ip)

        except api_exc.NsxApiException:
            with excutils.save_and_reraise_exception():
                LOG.exception(_LE("An error occurred while removing NAT rules "
                                  "on the NSX platform for floating ip:%s"),
                              floating_ip_address)
        except nsx_exc.NatRuleMismatch:
            # Do not surface to the user
            LOG.warning(_LW("An incorrect number of matching NAT rules "
                            "was found on the NSX platform"))

    def _remove_floatingip_address(self, context, fip_db):
        # Remove floating IP address from logical router port
        # Fetch logical port of router's external gateway
        router_id = fip_db.router_id
        nsx_router_id = nsx_utils.get_nsx_router_id(
            context.session, self.cluster, router_id)
        nsx_gw_port_id = routerlib.find_router_gw_port(
            context, self.cluster, nsx_router_id)['uuid']
        ext_neutron_port_db = self._get_port(context.elevated(),
                                             fip_db.floating_port_id)
        nsx_floating_ips = self._build_ip_address_list(
            context.elevated(), ext_neutron_port_db['fixed_ips'])
        routerlib.update_lrouter_port_ips(self.cluster,
                                          nsx_router_id,
                                          nsx_gw_port_id,
                                          ips_to_add=[],
                                          ips_to_remove=nsx_floating_ips)

    def _get_fip_assoc_data(self, context, fip, floatingip_db):
        if (('fixed_ip_address' in fip and fip['fixed_ip_address']) and
            not ('port_id' in fip and fip['port_id'])):
            msg = _("fixed_ip_address cannot be specified without a port_id")
            raise n_exc.BadRequest(resource='floatingip', msg=msg)
        port_id = internal_ip = router_id = None
        if 'port_id' in fip and fip['port_id']:
            fip_qry = context.session.query(l3_db.FloatingIP)
            port_id, internal_ip, router_id = self.get_assoc_data(
                context,
                fip,
                floatingip_db['floating_network_id'])
            try:
                fip_qry.filter_by(
                    fixed_port_id=fip['port_id'],
                    floating_network_id=floatingip_db['floating_network_id'],
                    fixed_ip_address=internal_ip).one()
                raise l3.FloatingIPPortAlreadyAssociated(
                    port_id=fip['port_id'],
                    fip_id=floatingip_db['id'],
                    floating_ip_address=floatingip_db['floating_ip_address'],
                    fixed_ip=floatingip_db['fixed_ip_address'],
                    net_id=floatingip_db['floating_network_id'])
            except sa_exc.NoResultFound:
                pass
        return (port_id, internal_ip, router_id)

    def _floatingip_status(self, floatingip_db, associated):
        if (associated and
            floatingip_db['status'] != constants.FLOATINGIP_STATUS_ACTIVE):
            return constants.FLOATINGIP_STATUS_ACTIVE
        elif (not associated and
              floatingip_db['status'] != constants.FLOATINGIP_STATUS_DOWN):
            return constants.FLOATINGIP_STATUS_DOWN
        # in any case ensure the status is not reset by this method!
        return floatingip_db['status']

    def _update_fip_assoc(self, context, fip, floatingip_db, external_port):
        """Update floating IP association data.

        Overrides method from base class.
        The method is augmented for creating NAT rules in the process.
        """
        # Store router currently serving the floating IP
        old_router_id = floatingip_db.router_id
        port_id, internal_ip, router_id = self._get_fip_assoc_data(
            context, fip, floatingip_db)
        floating_ip = floatingip_db['floating_ip_address']
        # If there's no association router_id will be None
        if router_id:
            nsx_router_id = nsx_utils.get_nsx_router_id(
                context.session, self.cluster, router_id)
            self._retrieve_and_delete_nat_rules(
                context, floating_ip, internal_ip, nsx_router_id)
            # Fetch logical port of router's external gateway
        # Fetch logical port of router's external gateway
        nsx_floating_ips = self._build_ip_address_list(
            context.elevated(), external_port['fixed_ips'])
        floating_ip = floatingip_db['floating_ip_address']
        # Retrieve and delete existing NAT rules, if any
        if old_router_id:
            nsx_old_router_id = nsx_utils.get_nsx_router_id(
                context.session, self.cluster, old_router_id)
            # Retrieve the current internal ip
            _p, _s, old_internal_ip = self._internal_fip_assoc_data(
                context, {'id': floatingip_db.id,
                          'port_id': floatingip_db.fixed_port_id,
                          'fixed_ip_address': floatingip_db.fixed_ip_address,
                          'tenant_id': floatingip_db.tenant_id})
            nsx_gw_port_id = routerlib.find_router_gw_port(
                context, self.cluster, nsx_old_router_id)['uuid']
            self._retrieve_and_delete_nat_rules(
                context, floating_ip, old_internal_ip, nsx_old_router_id)
            routerlib.update_lrouter_port_ips(
                self.cluster, nsx_old_router_id, nsx_gw_port_id,
                ips_to_add=[], ips_to_remove=nsx_floating_ips)

        if router_id:
            nsx_gw_port_id = routerlib.find_router_gw_port(
                context, self.cluster, nsx_router_id)['uuid']
            # Re-create NAT rules only if a port id is specified
            if fip.get('port_id'):
                try:
                    # Setup DNAT rules for the floating IP
                    routerlib.create_lrouter_dnat_rule(
                        self.cluster, nsx_router_id, internal_ip,
                        order=NSX_FLOATINGIP_NAT_RULES_ORDER,
                        match_criteria={'destination_ip_addresses':
                                        floating_ip})
                    # Setup SNAT rules for the floating IP
                    # Create a SNAT rule for enabling connectivity to the
                    # floating IP from the same network as the internal port
                    # Find subnet id for internal_ip from fixed_ips
                    internal_port = self._get_port(context, port_id)
                    # Cchecks not needed on statements below since otherwise
                    # _internal_fip_assoc_data would have raised
                    subnet_ids = [ip['subnet_id'] for ip in
                                  internal_port['fixed_ips'] if
                                  ip['ip_address'] == internal_ip]
                    internal_subnet_cidr = self._build_ip_address_list(
                        context, internal_port['fixed_ips'],
                        subnet_ids=subnet_ids)[0]
                    routerlib.create_lrouter_snat_rule(
                        self.cluster, nsx_router_id, floating_ip, floating_ip,
                        order=NSX_NOSNAT_RULES_ORDER - 1,
                        match_criteria={'source_ip_addresses':
                                        internal_subnet_cidr,
                                        'destination_ip_addresses':
                                        internal_ip})
                    # setup snat rule such that src ip of a IP packet when
                    # using floating is the floating ip itself.
                    routerlib.create_lrouter_snat_rule(
                        self.cluster, nsx_router_id, floating_ip, floating_ip,
                        order=NSX_FLOATINGIP_NAT_RULES_ORDER,
                        match_criteria={'source_ip_addresses': internal_ip})

                    # Add Floating IP address to router_port
                    routerlib.update_lrouter_port_ips(
                        self.cluster, nsx_router_id, nsx_gw_port_id,
                        ips_to_add=nsx_floating_ips, ips_to_remove=[])
                except api_exc.NsxApiException:
                    LOG.exception(_LE("An error occurred while creating NAT "
                                      "rules on the NSX platform for floating "
                                      "ip:%(floating_ip)s mapped to "
                                      "internal ip:%(internal_ip)s"),
                                  {'floating_ip': floating_ip,
                                   'internal_ip': internal_ip})
                    msg = _("Failed to update NAT rules for floatingip update")
                    raise nsx_exc.NsxPluginException(err_msg=msg)
        # Update also floating ip status (no need to call base class method)
        floatingip_db.update(
            {'fixed_ip_address': internal_ip,
             'fixed_port_id': port_id,
             'router_id': router_id,
             'status': self._floatingip_status(floatingip_db, router_id)})

    def delete_floatingip(self, context, id):
        fip_db = self._get_floatingip(context, id)
        # Check whether the floating ip is associated or not
        if fip_db.fixed_port_id:
            nsx_router_id = nsx_utils.get_nsx_router_id(
                context.session, self.cluster, fip_db.router_id)
            self._retrieve_and_delete_nat_rules(context,
                                                fip_db.floating_ip_address,
                                                fip_db.fixed_ip_address,
                                                nsx_router_id,
                                                min_num_rules_expected=1)
            # Remove floating IP address from logical router port
            self._remove_floatingip_address(context, fip_db)
        return super(NsxPluginV2, self).delete_floatingip(context, id)

    def disassociate_floatingips(self, context, port_id):
        try:
            fip_qry = context.session.query(l3_db.FloatingIP)
            fip_dbs = fip_qry.filter_by(fixed_port_id=port_id)

            for fip_db in fip_dbs:
                nsx_router_id = nsx_utils.get_nsx_router_id(
                    context.session, self.cluster, fip_db.router_id)
                self._retrieve_and_delete_nat_rules(context,
                                                    fip_db.floating_ip_address,
                                                    fip_db.fixed_ip_address,
                                                    nsx_router_id,
                                                    min_num_rules_expected=1)
                self._remove_floatingip_address(context, fip_db)
        except sa_exc.NoResultFound:
            LOG.debug("The port '%s' is not associated with floating IPs",
                      port_id)
        except n_exc.NotFound:
            LOG.warning(_LW("Nat rules not found in nsx for port: %s"), id)

        # NOTE(ihrachys): L3 agent notifications don't make sense for
        # NSX VMWare plugin since there is no L3 agent in such setup, so
        # disabling them here.
        super(NsxPluginV2, self).disassociate_floatingips(
            context, port_id, do_notify=False)

    def create_network_gateway(self, context, network_gateway):
        """Create a layer-2 network gateway.

        Create the gateway service on NSX platform and corresponding data
        structures in Neutron datase.
        """
        gw_data = network_gateway[networkgw.GATEWAY_RESOURCE_NAME]
        tenant_id = self._get_tenant_id_for_create(context, gw_data)
        # Ensure the default gateway in the config file is in sync with the db
        self._ensure_default_network_gateway()
        # Validate provided gateway device list
        self._validate_device_list(context, tenant_id, gw_data)
        devices = gw_data['devices']
        # Populate default physical network where not specified
        for device in devices:
            if not device.get('interface_name'):
                device['interface_name'] = self.cluster.default_interface_name
        try:
            # Replace Neutron device identifiers with NSX identifiers
            dev_map = dict((dev['id'], dev['interface_name']) for
                           dev in devices)
            nsx_devices = []
            for db_device in self._query_gateway_devices(
                context, filters={'id': [device['id'] for device in devices]}):
                nsx_devices.append(
                    {'id': db_device['nsx_id'],
                     'interface_name': dev_map[db_device['id']]})
            nsx_res = l2gwlib.create_l2_gw_service(
                self.cluster, tenant_id, gw_data['name'], nsx_devices)
            nsx_uuid = nsx_res.get('uuid')
        except api_exc.Conflict:
            raise nsx_exc.L2GatewayAlreadyInUse(gateway=gw_data['name'])
        except api_exc.NsxApiException:
            err_msg = _("Unable to create l2_gw_service for: %s") % gw_data
            LOG.exception(err_msg)
            raise nsx_exc.NsxPluginException(err_msg=err_msg)
        gw_data['id'] = nsx_uuid
        return super(NsxPluginV2, self).create_network_gateway(
            context, network_gateway, validate_device_list=False)

    def delete_network_gateway(self, context, gateway_id):
        """Remove a layer-2 network gateway.

        Remove the gateway service from NSX platform and corresponding data
        structures in Neutron datase.
        """
        # Ensure the default gateway in the config file is in sync with the db
        self._ensure_default_network_gateway()
        with context.session.begin(subtransactions=True):
            try:
                super(NsxPluginV2, self).delete_network_gateway(
                    context, gateway_id)
                l2gwlib.delete_l2_gw_service(self.cluster, gateway_id)
            except api_exc.ResourceNotFound:
                # Do not cause a 500 to be returned to the user if
                # the corresponding NSX resource does not exist
                LOG.exception(_LE("Unable to remove gateway service from "
                                  "NSX plaform - the resource was not found"))

    def get_network_gateway(self, context, id, fields=None):
        # Ensure the default gateway in the config file is in sync with the db
        self._ensure_default_network_gateway()
        return super(NsxPluginV2, self).get_network_gateway(context,
                                                            id, fields)

    def get_network_gateways(self, context, filters=None, fields=None,
                             sorts=None, limit=None, marker=None,
                             page_reverse=False):
        # Ensure the default gateway in the config file is in sync with the db
        self._ensure_default_network_gateway()
        # Ensure the tenant_id attribute is populated on returned gateways
        return super(NsxPluginV2, self).get_network_gateways(
            context, filters, fields, sorts, limit, marker, page_reverse)

    def update_network_gateway(self, context, id, network_gateway):
        # Ensure the default gateway in the config file is in sync with the db
        self._ensure_default_network_gateway()
        # Update gateway on backend when there's a name change
        name = network_gateway[networkgw.GATEWAY_RESOURCE_NAME].get('name')
        if name:
            try:
                l2gwlib.update_l2_gw_service(self.cluster, id, name)
            except api_exc.NsxApiException:
                # Consider backend failures as non-fatal, but still warn
                # because this might indicate something dodgy is going on
                LOG.warn(_LW("Unable to update name on NSX backend "
                             "for network gateway: %s"), id)
        return super(NsxPluginV2, self).update_network_gateway(
            context, id, network_gateway)

    def connect_network(self, context, network_gateway_id,
                        network_mapping_info):
        # Ensure the default gateway in the config file is in sync with the db
        self._ensure_default_network_gateway()
        try:
            return super(NsxPluginV2, self).connect_network(
                context, network_gateway_id, network_mapping_info)
        except api_exc.Conflict:
            raise nsx_exc.L2GatewayAlreadyInUse(gateway=network_gateway_id)

    def disconnect_network(self, context, network_gateway_id,
                           network_mapping_info):
        # Ensure the default gateway in the config file is in sync with the db
        self._ensure_default_network_gateway()
        return super(NsxPluginV2, self).disconnect_network(
            context, network_gateway_id, network_mapping_info)

    def _get_nsx_device_id(self, context, device_id):
        return self._get_gateway_device(context, device_id)['nsx_id']

    def _rollback_gw_device(self, context, device_id, gw_data=None,
                            new_status=None, is_create=False):
        LOG.error(_LE("Rolling back database changes for gateway device %s "
                      "because of an error in the NSX backend"), device_id)
        with context.session.begin(subtransactions=True):
            query = self._model_query(
                context, networkgw_db.NetworkGatewayDevice).filter(
                    networkgw_db.NetworkGatewayDevice.id == device_id)
            if is_create:
                query.delete(synchronize_session=False)
            else:
                super(NsxPluginV2, self).update_gateway_device(
                    context, device_id,
                    {networkgw.DEVICE_RESOURCE_NAME: gw_data})
                if new_status:
                    query.update({'status': new_status},
                                 synchronize_session=False)

    # TODO(salv-orlando): Handlers for Gateway device operations should be
    # moved into the appropriate nsx_handlers package once the code for the
    # blueprint nsx-async-backend-communication merges
    def create_gateway_device_handler(self, context, gateway_device,
                                      client_certificate):
        neutron_id = gateway_device['id']
        try:
            nsx_res = l2gwlib.create_gateway_device(
                self.cluster,
                gateway_device['tenant_id'],
                gateway_device['name'],
                neutron_id,
                self.cluster.default_tz_uuid,
                gateway_device['connector_type'],
                gateway_device['connector_ip'],
                client_certificate)

            # Fetch status (it needs another NSX API call)
            device_status = nsx_utils.get_nsx_device_status(self.cluster,
                                                            nsx_res['uuid'])

            # set NSX GW device in neutron database and update status
            with context.session.begin(subtransactions=True):
                query = self._model_query(
                    context, networkgw_db.NetworkGatewayDevice).filter(
                        networkgw_db.NetworkGatewayDevice.id == neutron_id)
                query.update({'status': device_status,
                              'nsx_id': nsx_res['uuid']},
                             synchronize_session=False)
            LOG.debug("Neutron gateway device: %(neutron_id)s; "
                      "NSX transport node identifier: %(nsx_id)s; "
                      "Operational status: %(status)s.",
                      {'neutron_id': neutron_id,
                       'nsx_id': nsx_res['uuid'],
                       'status': device_status})
            return device_status
        except (nsx_exc.InvalidSecurityCertificate, api_exc.NsxApiException):
            with excutils.save_and_reraise_exception():
                self._rollback_gw_device(context, neutron_id, is_create=True)

    def update_gateway_device_handler(self, context, gateway_device,
                                      old_gateway_device_data,
                                      client_certificate):
        nsx_id = gateway_device['nsx_id']
        neutron_id = gateway_device['id']
        try:
            l2gwlib.update_gateway_device(
                self.cluster,
                nsx_id,
                gateway_device['tenant_id'],
                gateway_device['name'],
                neutron_id,
                self.cluster.default_tz_uuid,
                gateway_device['connector_type'],
                gateway_device['connector_ip'],
                client_certificate)

            # Fetch status (it needs another NSX API call)
            device_status = nsx_utils.get_nsx_device_status(self.cluster,
                                                            nsx_id)
            # update status
            with context.session.begin(subtransactions=True):
                query = self._model_query(
                    context, networkgw_db.NetworkGatewayDevice).filter(
                        networkgw_db.NetworkGatewayDevice.id == neutron_id)
                query.update({'status': device_status},
                             synchronize_session=False)
            LOG.debug("Neutron gateway device: %(neutron_id)s; "
                      "NSX transport node identifier: %(nsx_id)s; "
                      "Operational status: %(status)s.",
                      {'neutron_id': neutron_id,
                       'nsx_id': nsx_id,
                       'status': device_status})
            return device_status
        except (nsx_exc.InvalidSecurityCertificate, api_exc.NsxApiException):
            with excutils.save_and_reraise_exception():
                self._rollback_gw_device(context, neutron_id,
                                         gw_data=old_gateway_device_data)
        except n_exc.NotFound:
            # The gateway device was probably deleted in the backend.
            # The DB change should be rolled back and the status must
            # be put in error
            with excutils.save_and_reraise_exception():
                self._rollback_gw_device(context, neutron_id,
                                         gw_data=old_gateway_device_data,
                                         new_status=networkgw_db.ERROR)

    def get_gateway_device(self, context, device_id, fields=None):
        # Get device from database
        gw_device = super(NsxPluginV2, self).get_gateway_device(
            context, device_id, fields, include_nsx_id=True)
        # Fetch status from NSX
        nsx_id = gw_device['nsx_id']
        device_status = nsx_utils.get_nsx_device_status(self.cluster, nsx_id)
        # TODO(salv-orlando): Asynchronous sync for gateway device status
        # Update status in database
        with context.session.begin(subtransactions=True):
            query = self._model_query(
                context, networkgw_db.NetworkGatewayDevice).filter(
                    networkgw_db.NetworkGatewayDevice.id == device_id)
            query.update({'status': device_status},
                         synchronize_session=False)
        gw_device['status'] = device_status
        return gw_device

    def get_gateway_devices(self, context, filters=None, fields=None,
                            sorts=None, limit=None, marker=None,
                            page_reverse=False):
        # Get devices from database
        devices = super(NsxPluginV2, self).get_gateway_devices(
            context, filters, fields, include_nsx_id=True)
        # Fetch operational status from NSX, filter by tenant tag
        # TODO(salv-orlando): Asynchronous sync for gateway device status
        tenant_id = context.tenant_id if not context.is_admin else None
        nsx_statuses = nsx_utils.get_nsx_device_statuses(self.cluster,
                                                         tenant_id)
        # Update statuses in database
        with context.session.begin(subtransactions=True):
            for device in devices:
                new_status = nsx_statuses.get(device['nsx_id'])
                if new_status:
                    device['status'] = new_status
        return devices

    def create_gateway_device(self, context, gateway_device):
        # NOTE(salv-orlando): client-certificate will not be stored
        # in the database
        device_data = gateway_device[networkgw.DEVICE_RESOURCE_NAME]
        client_certificate = device_data.pop('client_certificate')
        gw_device = super(NsxPluginV2, self).create_gateway_device(
            context, gateway_device)
        # DB operation was successful, perform NSX operation
        gw_device['status'] = self.create_gateway_device_handler(
            context, gw_device, client_certificate)
        return gw_device

    def update_gateway_device(self, context, device_id,
                              gateway_device):
        # NOTE(salv-orlando): client-certificate will not be stored
        # in the database
        client_certificate = (
            gateway_device[networkgw.DEVICE_RESOURCE_NAME].pop(
                'client_certificate', None))
        # Retrive current state from DB in case a rollback should be needed
        old_gw_device_data = super(NsxPluginV2, self).get_gateway_device(
            context, device_id, include_nsx_id=True)
        gw_device = super(NsxPluginV2, self).update_gateway_device(
            context, device_id, gateway_device, include_nsx_id=True)
        # DB operation was successful, perform NSX operation
        gw_device['status'] = self.update_gateway_device_handler(
            context, gw_device, old_gw_device_data, client_certificate)
        gw_device.pop('nsx_id')
        return gw_device

    def delete_gateway_device(self, context, device_id):
        nsx_device_id = self._get_nsx_device_id(context, device_id)
        super(NsxPluginV2, self).delete_gateway_device(
            context, device_id)
        # DB operation was successful, perform NSX operation
        # TODO(salv-orlando): State consistency with neutron DB
        # should be ensured even in case of backend failures
        try:
            l2gwlib.delete_gateway_device(self.cluster, nsx_device_id)
        except n_exc.NotFound:
            LOG.warn(_LW("Removal of gateway device: %(neutron_id)s failed on "
                         "NSX backend (NSX id:%(nsx_id)s) because the NSX "
                         "resource was not found"),
                     {'neutron_id': device_id, 'nsx_id': nsx_device_id})
        except api_exc.NsxApiException:
            with excutils.save_and_reraise_exception():
                # In this case a 500 should be returned
                LOG.exception(_LE("Removal of gateway device: %(neutron_id)s "
                                  "failed on NSX backend (NSX id:%(nsx_id)s). "
                                  "Neutron and NSX states have diverged."),
                              {'neutron_id': device_id,
                               'nsx_id': nsx_device_id})

    def create_security_group(self, context, security_group, default_sg=False):
        """Create security group.

        If default_sg is true that means we are creating a default security
        group and we don't need to check if one exists.
        """
        s = security_group.get('security_group')

        tenant_id = self._get_tenant_id_for_create(context, s)
        if not default_sg:
            self._ensure_default_security_group(context, tenant_id)
        # NOTE(salv-orlando): Pre-generating Neutron ID for security group.
        neutron_id = str(uuid.uuid4())
        nsx_secgroup = secgrouplib.create_security_profile(
            self.cluster, tenant_id, neutron_id, s)
        with context.session.begin(subtransactions=True):
            s['id'] = neutron_id
            sec_group = super(NsxPluginV2, self).create_security_group(
                context, security_group, default_sg)
            context.session.flush()
            # Add mapping between neutron and nsx identifiers
            nsx_db.add_neutron_nsx_security_group_mapping(
                context.session, neutron_id, nsx_secgroup['uuid'])
        return sec_group

    def update_security_group(self, context, secgroup_id, security_group):
        secgroup = (super(NsxPluginV2, self).
                    update_security_group(context,
                                          secgroup_id,
                                          security_group))
        if ('name' in security_group['security_group'] and
            secgroup['name'] != 'default'):
            nsx_sec_profile_id = nsx_utils.get_nsx_security_group_id(
                context.session, self.cluster, secgroup_id)
            try:
                name = security_group['security_group']['name']
                secgrouplib.update_security_profile(
                    self.cluster, nsx_sec_profile_id, name)
            except (n_exc.NotFound, api_exc.NsxApiException) as e:
                # Reverting the DB change is not really worthwhile
                # for a mismatch between names. It's the rules that
                # we care about.
                LOG.error(_LE('Error while updating security profile '
                              '%(uuid)s with name %(name)s: %(error)s.'),
                          {'uuid': secgroup_id, 'name': name, 'error': e})
        return secgroup

    def delete_security_group(self, context, security_group_id):
        """Delete a security group.

        :param security_group_id: security group rule to remove.
        """
        with context.session.begin(subtransactions=True):
            security_group = super(NsxPluginV2, self).get_security_group(
                context, security_group_id)
            if not security_group:
                raise ext_sg.SecurityGroupNotFound(id=security_group_id)

            if security_group['name'] == 'default' and not context.is_admin:
                raise ext_sg.SecurityGroupCannotRemoveDefault()

            filters = {'security_group_id': [security_group['id']]}
            if super(NsxPluginV2, self)._get_port_security_group_bindings(
                context, filters):
                raise ext_sg.SecurityGroupInUse(id=security_group['id'])
            nsx_sec_profile_id = nsx_utils.get_nsx_security_group_id(
                context.session, self.cluster, security_group_id)

            try:
                secgrouplib.delete_security_profile(
                    self.cluster, nsx_sec_profile_id)
            except n_exc.NotFound:
                # The security profile was not found on the backend
                # do not fail in this case.
                LOG.warning(_LW("The NSX security profile %(sec_profile_id)s, "
                                "associated with the Neutron security group "
                                "%(sec_group_id)s was not found on the "
                                "backend"),
                            {'sec_profile_id': nsx_sec_profile_id,
                             'sec_group_id': security_group_id})
            except api_exc.NsxApiException:
                # Raise and fail the operation, as there is a problem which
                # prevented the sec group from being removed from the backend
                LOG.exception(_LE("An exception occurred while removing the "
                                  "NSX security profile %(sec_profile_id)s, "
                                  "associated with Netron security group "
                                  "%(sec_group_id)s"),
                              {'sec_profile_id': nsx_sec_profile_id,
                               'sec_group_id': security_group_id})
                raise nsx_exc.NsxPluginException(
                    _("Unable to remove security group %s from backend"),
                    security_group['id'])
            return super(NsxPluginV2, self).delete_security_group(
                context, security_group_id)

    def _validate_security_group_rules(self, context, rules):
        for rule in rules['security_group_rules']:
            r = rule.get('security_group_rule')
            port_based_proto = (self._get_ip_proto_number(r['protocol'])
                                in securitygroups_db.IP_PROTOCOL_MAP.values())
            if (not port_based_proto and
                (r['port_range_min'] is not None or
                 r['port_range_max'] is not None)):
                msg = (_("Port values not valid for "
                         "protocol: %s") % r['protocol'])
                raise n_exc.BadRequest(resource='security_group_rule',
                                       msg=msg)
        return super(NsxPluginV2, self)._validate_security_group_rules(context,
                                                                       rules)

    def create_security_group_rule(self, context, security_group_rule):
        """Create a single security group rule."""
        bulk_rule = {'security_group_rules': [security_group_rule]}
        return self.create_security_group_rule_bulk(context, bulk_rule)[0]

    def create_security_group_rule_bulk(self, context, security_group_rule):
        """Create security group rules.

        :param security_group_rule: list of rules to create
        """
        s = security_group_rule.get('security_group_rules')

        # TODO(arosen) is there anyway we could avoid having the update of
        # the security group rules in nsx outside of this transaction?
        with context.session.begin(subtransactions=True):
            security_group_id = self._validate_security_group_rules(
                context, security_group_rule)
            # Check to make sure security group exists
            security_group = super(NsxPluginV2, self).get_security_group(
                context, security_group_id)

            if not security_group:
                raise ext_sg.SecurityGroupNotFound(id=security_group_id)
            # Check for duplicate rules
            self._check_for_duplicate_rules(context, s)
            # gather all the existing security group rules since we need all
            # of them to PUT to NSX.
            existing_rules = self.get_security_group_rules(
                context, {'security_group_id': [security_group['id']]})
            combined_rules = sg_utils.merge_security_group_rules_with_current(
                context.session, self.cluster, s, existing_rules)
            nsx_sec_profile_id = nsx_utils.get_nsx_security_group_id(
                context.session, self.cluster, security_group_id)
            secgrouplib.update_security_group_rules(self.cluster,
                                                    nsx_sec_profile_id,
                                                    combined_rules)
            return super(
                NsxPluginV2, self).create_security_group_rule_bulk_native(
                    context, security_group_rule)

    def delete_security_group_rule(self, context, sgrid):
        """Delete a security group rule
        :param sgrid: security group id to remove.
        """
        with context.session.begin(subtransactions=True):
            # determine security profile id
            security_group_rule = (
                super(NsxPluginV2, self).get_security_group_rule(
                    context, sgrid))
            if not security_group_rule:
                raise ext_sg.SecurityGroupRuleNotFound(id=sgrid)

            sgid = security_group_rule['security_group_id']
            current_rules = self.get_security_group_rules(
                context, {'security_group_id': [sgid]})
            current_rules_nsx = sg_utils.get_security_group_rules_nsx_format(
                context.session, self.cluster, current_rules, True)

            sg_utils.remove_security_group_with_id_and_id_field(
                current_rules_nsx, sgrid)
            nsx_sec_profile_id = nsx_utils.get_nsx_security_group_id(
                context.session, self.cluster, sgid)
            secgrouplib.update_security_group_rules(
                self.cluster, nsx_sec_profile_id, current_rules_nsx)
            return super(NsxPluginV2, self).delete_security_group_rule(context,
                                                                       sgrid)

    def create_qos_queue(self, context, qos_queue, check_policy=True):
        q = qos_queue.get('qos_queue')
        self._validate_qos_queue(context, q)
        q['id'] = queuelib.create_lqueue(self.cluster, q)
        return super(NsxPluginV2, self).create_qos_queue(context, qos_queue)

    def delete_qos_queue(self, context, queue_id, raise_in_use=True):
        filters = {'queue_id': [queue_id]}
        queues = self._get_port_queue_bindings(context, filters)
        if queues:
            if raise_in_use:
                raise qos.QueueInUseByPort()
            else:
                return
        queuelib.delete_lqueue(self.cluster, queue_id)
        return super(NsxPluginV2, self).delete_qos_queue(context, queue_id)
