# 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 netaddr
from oslo_db import exception as db_exc
from oslo_log import log as logging
from oslo_utils import uuidutils
import sqlalchemy as sa
from sqlalchemy import orm
from sqlalchemy.orm import exc
from sqlalchemy.orm import scoped_session

from neutron.api.v2 import attributes
from neutron.callbacks import events
from neutron.callbacks import exceptions
from neutron.callbacks import registry
from neutron.callbacks import resources
from neutron.common import constants
from neutron.common import utils
from neutron.db import api as db_api
from neutron.db import db_base_plugin_v2
from neutron.db import model_base
from neutron.db import models_v2
from neutron.extensions import securitygroup as ext_sg


LOG = logging.getLogger(__name__)

IP_PROTOCOL_MAP = {constants.PROTO_NAME_TCP: constants.PROTO_NUM_TCP,
                   constants.PROTO_NAME_UDP: constants.PROTO_NUM_UDP,
                   constants.PROTO_NAME_ICMP: constants.PROTO_NUM_ICMP,
                   constants.PROTO_NAME_ICMP_V6: constants.PROTO_NUM_ICMP_V6}


class SecurityGroup(model_base.BASEV2, models_v2.HasId, models_v2.HasTenant):
    """Represents a v2 neutron security group."""

    name = sa.Column(sa.String(255))
    description = sa.Column(sa.String(255))


class DefaultSecurityGroup(model_base.BASEV2):
    __tablename__ = 'default_security_group'

    tenant_id = sa.Column(sa.String(255), primary_key=True, nullable=False)
    security_group_id = sa.Column(sa.String(36),
                                  sa.ForeignKey("securitygroups.id",
                                                ondelete="CASCADE"),
                                  nullable=False)
    security_group = orm.relationship(
        SecurityGroup, lazy='joined',
        backref=orm.backref('default_security_group', cascade='all,delete'),
        primaryjoin="SecurityGroup.id==DefaultSecurityGroup.security_group_id",
    )


class SecurityGroupPortBinding(model_base.BASEV2):
    """Represents binding between neutron ports and security profiles."""

    port_id = sa.Column(sa.String(36),
                        sa.ForeignKey("ports.id",
                                      ondelete='CASCADE'),
                        primary_key=True)
    security_group_id = sa.Column(sa.String(36),
                                  sa.ForeignKey("securitygroups.id"),
                                  primary_key=True)

    # Add a relationship to the Port model in order to instruct SQLAlchemy to
    # eagerly load security group bindings
    ports = orm.relationship(
        models_v2.Port,
        backref=orm.backref("security_groups",
                            lazy='joined', cascade='delete'))


class SecurityGroupRule(model_base.BASEV2, models_v2.HasId,
                        models_v2.HasTenant):
    """Represents a v2 neutron security group rule."""

    security_group_id = sa.Column(sa.String(36),
                                  sa.ForeignKey("securitygroups.id",
                                                ondelete="CASCADE"),
                                  nullable=False)

    remote_group_id = sa.Column(sa.String(36),
                                sa.ForeignKey("securitygroups.id",
                                              ondelete="CASCADE"),
                                nullable=True)

    direction = sa.Column(sa.Enum('ingress', 'egress',
                                  name='securitygrouprules_direction'))
    ethertype = sa.Column(sa.String(40))
    protocol = sa.Column(sa.String(40))
    port_range_min = sa.Column(sa.Integer)
    port_range_max = sa.Column(sa.Integer)
    remote_ip_prefix = sa.Column(sa.String(255))
    security_group = orm.relationship(
        SecurityGroup,
        backref=orm.backref('rules', cascade='all,delete', lazy='joined'),
        primaryjoin="SecurityGroup.id==SecurityGroupRule.security_group_id")
    source_group = orm.relationship(
        SecurityGroup,
        backref=orm.backref('source_rules', cascade='all,delete'),
        primaryjoin="SecurityGroup.id==SecurityGroupRule.remote_group_id")


class SecurityGroupDbMixin(ext_sg.SecurityGroupPluginBase):
    """Mixin class to add security group to db_base_plugin_v2."""

    __native_bulk_support = True

    def create_security_group_bulk(self, context, security_group_rule):
        return self._create_bulk('security_group', context,
                                 security_group_rule)

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

        If default_sg is true that means we are a default security group for
        a given tenant if it does not exist.
        """
        s = security_group['security_group']
        kwargs = {
            'context': context,
            'security_group': s,
            'is_default': default_sg,
        }
        # NOTE(armax): a callback exception here will prevent the request
        # from being processed. This is a hook point for backend's validation;
        # we raise to propagate the reason for the failure.
        try:
            registry.notify(
                resources.SECURITY_GROUP, events.BEFORE_CREATE, self,
                **kwargs)
        except exceptions.CallbackFailure as e:
            raise ext_sg.SecurityGroupConflict(reason=e)

        tenant_id = self._get_tenant_id_for_create(context, s)

        if not default_sg:
            self._ensure_default_security_group(context, tenant_id)

        with db_api.autonested_transaction(context.session):
            security_group_db = SecurityGroup(id=s.get('id') or (
                                              uuidutils.generate_uuid()),
                                              description=s['description'],
                                              tenant_id=tenant_id,
                                              name=s['name'])
            context.session.add(security_group_db)
            if default_sg:
                context.session.add(DefaultSecurityGroup(
                    security_group=security_group_db,
                    tenant_id=security_group_db['tenant_id']))
            for ethertype in ext_sg.sg_supported_ethertypes:
                if default_sg:
                    # Allow intercommunication
                    ingress_rule = SecurityGroupRule(
                        id=uuidutils.generate_uuid(), tenant_id=tenant_id,
                        security_group=security_group_db,
                        direction='ingress',
                        ethertype=ethertype,
                        source_group=security_group_db)
                    context.session.add(ingress_rule)

                egress_rule = SecurityGroupRule(
                    id=uuidutils.generate_uuid(), tenant_id=tenant_id,
                    security_group=security_group_db,
                    direction='egress',
                    ethertype=ethertype)
                context.session.add(egress_rule)

        secgroup_dict = self._make_security_group_dict(security_group_db)

        kwargs['security_group'] = secgroup_dict
        registry.notify(resources.SECURITY_GROUP, events.AFTER_CREATE, self,
                        **kwargs)
        return secgroup_dict

    def get_security_groups(self, context, filters=None, fields=None,
                            sorts=None, limit=None,
                            marker=None, page_reverse=False, default_sg=False):

        # If default_sg is True do not call _ensure_default_security_group()
        # so this can be done recursively. Context.tenant_id is checked
        # because all the unit tests do not explicitly set the context on
        # GETS. TODO(arosen)  context handling can probably be improved here.
        if not default_sg and context.tenant_id:
            tenant_id = filters.get('tenant_id')
            if tenant_id:
                tenant_id = tenant_id[0]
            else:
                tenant_id = context.tenant_id
            self._ensure_default_security_group(context, tenant_id)
        marker_obj = self._get_marker_obj(context, 'security_group', limit,
                                          marker)
        return self._get_collection(context,
                                    SecurityGroup,
                                    self._make_security_group_dict,
                                    filters=filters, fields=fields,
                                    sorts=sorts,
                                    limit=limit, marker_obj=marker_obj,
                                    page_reverse=page_reverse)

    def get_security_groups_count(self, context, filters=None):
        return self._get_collection_count(context, SecurityGroup,
                                          filters=filters)

    def get_security_group(self, context, id, fields=None, tenant_id=None):
        """Tenant id is given to handle the case when creating a security
        group rule on behalf of another use.
        """

        if tenant_id:
            tmp_context_tenant_id = context.tenant_id
            context.tenant_id = tenant_id

        try:
            with context.session.begin(subtransactions=True):
                ret = self._make_security_group_dict(self._get_security_group(
                                                     context, id), fields)
                ret['security_group_rules'] = self.get_security_group_rules(
                    context, {'security_group_id': [id]})
        finally:
            if tenant_id:
                context.tenant_id = tmp_context_tenant_id
        return ret

    def _get_security_group(self, context, id):
        try:
            query = self._model_query(context, SecurityGroup)
            sg = query.filter(SecurityGroup.id == id).one()

        except exc.NoResultFound:
            raise ext_sg.SecurityGroupNotFound(id=id)
        return sg

    def delete_security_group(self, context, id):
        filters = {'security_group_id': [id]}
        ports = self._get_port_security_group_bindings(context, filters)
        if ports:
            raise ext_sg.SecurityGroupInUse(id=id)
        # confirm security group exists
        sg = self._get_security_group(context, id)

        if sg['name'] == 'default' and not context.is_admin:
            raise ext_sg.SecurityGroupCannotRemoveDefault()
        kwargs = {
            'context': context,
            'security_group_id': id,
            'security_group': sg,
        }
        # NOTE(armax): a callback exception here will prevent the request
        # from being processed. This is a hook point for backend's validation;
        # we raise to propagate the reason for the failure.
        try:
            registry.notify(
                resources.SECURITY_GROUP, events.BEFORE_DELETE, self,
                **kwargs)
        except exceptions.CallbackFailure as e:
            reason = _('cannot be deleted due to %s') % e
            raise ext_sg.SecurityGroupInUse(id=id, reason=reason)

        with context.session.begin(subtransactions=True):
            context.session.delete(sg)

        kwargs.pop('security_group')
        registry.notify(resources.SECURITY_GROUP, events.AFTER_DELETE, self,
                        **kwargs)

    def update_security_group(self, context, id, security_group):
        s = security_group['security_group']

        kwargs = {
            'context': context,
            'security_group_id': id,
            'security_group': s,
        }
        # NOTE(armax): a callback exception here will prevent the request
        # from being processed. This is a hook point for backend's validation;
        # we raise to propagate the reason for the failure.
        try:
            registry.notify(
                resources.SECURITY_GROUP, events.BEFORE_UPDATE, self,
                **kwargs)
        except exceptions.CallbackFailure as e:
            raise ext_sg.SecurityGroupConflict(reason=e)

        with context.session.begin(subtransactions=True):
            sg = self._get_security_group(context, id)
            if sg['name'] == 'default' and 'name' in s:
                raise ext_sg.SecurityGroupCannotUpdateDefault()
            sg.update(s)
        sg_dict = self._make_security_group_dict(sg)

        kwargs['security_group'] = sg_dict
        registry.notify(resources.SECURITY_GROUP, events.AFTER_UPDATE, self,
                        **kwargs)
        return sg_dict

    def _make_security_group_dict(self, security_group, fields=None):
        res = {'id': security_group['id'],
               'name': security_group['name'],
               'tenant_id': security_group['tenant_id'],
               'description': security_group['description']}
        res['security_group_rules'] = [self._make_security_group_rule_dict(r)
                                       for r in security_group.rules]
        return self._fields(res, fields)

    def _make_security_group_binding_dict(self, security_group, fields=None):
        res = {'port_id': security_group['port_id'],
               'security_group_id': security_group['security_group_id']}
        return self._fields(res, fields)

    def _create_port_security_group_binding(self, context, port_id,
                                            security_group_id):
        with context.session.begin(subtransactions=True):
            db = SecurityGroupPortBinding(port_id=port_id,
                                          security_group_id=security_group_id)
            context.session.add(db)

    def _get_port_security_group_bindings(self, context,
                                          filters=None, fields=None):
        return self._get_collection(context,
                                    SecurityGroupPortBinding,
                                    self._make_security_group_binding_dict,
                                    filters=filters, fields=fields)

    def _delete_port_security_group_bindings(self, context, port_id):
        query = self._model_query(context, SecurityGroupPortBinding)
        bindings = query.filter(
            SecurityGroupPortBinding.port_id == port_id)
        with context.session.begin(subtransactions=True):
            for binding in bindings:
                context.session.delete(binding)

    def create_security_group_rule_bulk(self, context, security_group_rules):
        return self._create_bulk('security_group_rule', context,
                                 security_group_rules)

    def create_security_group_rule_bulk_native(self, context,
                                               security_group_rules):
        rules = security_group_rules['security_group_rules']
        scoped_session(context.session)
        security_group_id = self._validate_security_group_rules(
            context, security_group_rules)
        with context.session.begin(subtransactions=True):
            if not self.get_security_group(context, security_group_id):
                raise ext_sg.SecurityGroupNotFound(id=security_group_id)

            self._check_for_duplicate_rules(context, rules)
            ret = []
            for rule_dict in rules:
                res_rule_dict = self._create_security_group_rule(
                    context, rule_dict, validate=False)
                ret.append(res_rule_dict)
            return ret

    def create_security_group_rule(self, context, security_group_rule):
        return self._create_security_group_rule(context, security_group_rule)

    def _create_security_group_rule(self, context, security_group_rule,
                                    validate=True):
        if validate:
            self._validate_security_group_rule(context, security_group_rule)
            self._check_for_duplicate_rules_in_db(context, security_group_rule)

        rule_dict = security_group_rule['security_group_rule']
        kwargs = {
            'context': context,
            'security_group_rule': rule_dict
        }
        # NOTE(armax): a callback exception here will prevent the request
        # from being processed. This is a hook point for backend's validation;
        # we raise to propagate the reason for the failure.
        try:
            registry.notify(
                resources.SECURITY_GROUP_RULE, events.BEFORE_CREATE, self,
                **kwargs)
        except exceptions.CallbackFailure as e:
            raise ext_sg.SecurityGroupConflict(reason=e)

        tenant_id = self._get_tenant_id_for_create(context, rule_dict)
        with context.session.begin(subtransactions=True):
            db = SecurityGroupRule(
                id=(rule_dict.get('id') or uuidutils.generate_uuid()),
                tenant_id=tenant_id,
                security_group_id=rule_dict['security_group_id'],
                direction=rule_dict['direction'],
                remote_group_id=rule_dict.get('remote_group_id'),
                ethertype=rule_dict['ethertype'],
                protocol=rule_dict['protocol'],
                port_range_min=rule_dict['port_range_min'],
                port_range_max=rule_dict['port_range_max'],
                remote_ip_prefix=rule_dict.get('remote_ip_prefix'))
            context.session.add(db)
        res_rule_dict = self._make_security_group_rule_dict(db)
        kwargs['security_group_rule'] = res_rule_dict
        registry.notify(
            resources.SECURITY_GROUP_RULE, events.AFTER_CREATE, self,
            **kwargs)
        return res_rule_dict

    def _get_ip_proto_number(self, protocol):
        if protocol is None:
            return
        # According to bug 1381379, protocol is always set to string to avoid
        # problems with comparing int and string in PostgreSQL. Here this
        # string is converted to int to give an opportunity to use it as
        # before.
        return int(IP_PROTOCOL_MAP.get(protocol, protocol))

    def _validate_port_range(self, rule):
        """Check that port_range is valid."""
        if (rule['port_range_min'] is None and
            rule['port_range_max'] is None):
            return
        if not rule['protocol']:
            raise ext_sg.SecurityGroupProtocolRequiredWithPorts()
        ip_proto = self._get_ip_proto_number(rule['protocol'])
        if ip_proto in [constants.PROTO_NUM_TCP, constants.PROTO_NUM_UDP]:
            if (rule['port_range_min'] is not None and
                rule['port_range_max'] is not None and
                rule['port_range_min'] <= rule['port_range_max']):
                pass
            else:
                raise ext_sg.SecurityGroupInvalidPortRange()
        elif ip_proto == constants.PROTO_NUM_ICMP:
            for attr, field in [('port_range_min', 'type'),
                                ('port_range_max', 'code')]:
                if rule[attr] is not None and not (0 <= rule[attr] <= 255):
                    raise ext_sg.SecurityGroupInvalidIcmpValue(
                        field=field, attr=attr, value=rule[attr])
            if (rule['port_range_min'] is None and
                    rule['port_range_max'] is not None):
                raise ext_sg.SecurityGroupMissingIcmpType(
                    value=rule['port_range_max'])

    def _validate_single_tenant_and_group(self, security_group_rules):
        """Check that all rules belong to the same security group and tenant
        """
        sg_groups = set()
        tenants = set()
        for rule_dict in security_group_rules['security_group_rules']:
            rule = rule_dict['security_group_rule']
            sg_groups.add(rule['security_group_id'])
            if len(sg_groups) > 1:
                raise ext_sg.SecurityGroupNotSingleGroupRules()

            tenants.add(rule['tenant_id'])
            if len(tenants) > 1:
                raise ext_sg.SecurityGroupRulesNotSingleTenant()
        return sg_groups.pop()

    def _validate_security_group_rule(self, context, security_group_rule):
        rule = security_group_rule['security_group_rule']
        self._validate_port_range(rule)
        self._validate_ip_prefix(rule)

        if rule['remote_ip_prefix'] and rule['remote_group_id']:
            raise ext_sg.SecurityGroupRemoteGroupAndRemoteIpPrefix()

        remote_group_id = rule['remote_group_id']
        # Check that remote_group_id exists for tenant
        if remote_group_id:
            self.get_security_group(context, remote_group_id,
                                    tenant_id=rule['tenant_id'])

        security_group_id = rule['security_group_id']

        # Confirm that the tenant has permission
        # to add rules to this security group.
        self.get_security_group(context, security_group_id,
                                tenant_id=rule['tenant_id'])
        return security_group_id

    def _validate_security_group_rules(self, context, security_group_rules):
        sg_id = self._validate_single_tenant_and_group(security_group_rules)
        for rule in security_group_rules['security_group_rules']:
            self._validate_security_group_rule(context, rule)
        return sg_id

    def _make_security_group_rule_dict(self, security_group_rule, fields=None):
        res = {'id': security_group_rule['id'],
               'tenant_id': security_group_rule['tenant_id'],
               'security_group_id': security_group_rule['security_group_id'],
               'ethertype': security_group_rule['ethertype'],
               'direction': security_group_rule['direction'],
               'protocol': security_group_rule['protocol'],
               'port_range_min': security_group_rule['port_range_min'],
               'port_range_max': security_group_rule['port_range_max'],
               'remote_ip_prefix': security_group_rule['remote_ip_prefix'],
               'remote_group_id': security_group_rule['remote_group_id']}

        return self._fields(res, fields)

    def _make_security_group_rule_filter_dict(self, security_group_rule):
        sgr = security_group_rule['security_group_rule']
        res = {'tenant_id': [sgr['tenant_id']],
               'security_group_id': [sgr['security_group_id']],
               'direction': [sgr['direction']]}

        include_if_present = ['protocol', 'port_range_max', 'port_range_min',
                              'ethertype', 'remote_ip_prefix',
                              'remote_group_id']
        for key in include_if_present:
            value = sgr.get(key)
            if value:
                res[key] = [value]
        return res

    def _check_for_duplicate_rules(self, context, security_group_rules):
        for i in security_group_rules:
            found_self = False
            for j in security_group_rules:
                if i['security_group_rule'] == j['security_group_rule']:
                    if found_self:
                        raise ext_sg.DuplicateSecurityGroupRuleInPost(rule=i)
                    found_self = True

            self._check_for_duplicate_rules_in_db(context, i)

    def _check_for_duplicate_rules_in_db(self, context, security_group_rule):
        # Check in database if rule exists
        filters = self._make_security_group_rule_filter_dict(
            security_group_rule)
        db_rules = self.get_security_group_rules(context, filters)
        # Note(arosen): the call to get_security_group_rules wildcards
        # values in the filter that have a value of [None]. For
        # example, filters = {'remote_group_id': [None]} will return
        # all security group rules regardless of their value of
        # remote_group_id. Therefore it is not possible to do this
        # query unless the behavior of _get_collection()
        # is changed which cannot be because other methods are already
        # relying on this behavior. Therefore, we do the filtering
        # below to check for these corner cases.
        for db_rule in db_rules:
            # need to remove id from db_rule for matching
            id = db_rule.pop('id')
            if (security_group_rule['security_group_rule'] == db_rule):
                raise ext_sg.SecurityGroupRuleExists(id=id)

    def _validate_ip_prefix(self, rule):
        """Check that a valid cidr was specified as remote_ip_prefix

        No need to check that it is in fact an IP address as this is already
        validated by attribute validators.
        Check that rule ethertype is consistent with remote_ip_prefix ip type.
        Add mask to ip_prefix if absent (192.168.1.10 -> 192.168.1.10/32).
        """
        input_prefix = rule['remote_ip_prefix']
        if input_prefix:
            addr = netaddr.IPNetwork(input_prefix)
            # set input_prefix to always include the netmask:
            rule['remote_ip_prefix'] = str(addr)
            # check consistency of ethertype with addr version
            if rule['ethertype'] != "IPv%d" % (addr.version):
                raise ext_sg.SecurityGroupRuleParameterConflict(
                    ethertype=rule['ethertype'], cidr=input_prefix)

    def get_security_group_rules(self, context, filters=None, fields=None,
                                 sorts=None, limit=None, marker=None,
                                 page_reverse=False):
        marker_obj = self._get_marker_obj(context, 'security_group_rule',
                                          limit, marker)
        return self._get_collection(context,
                                    SecurityGroupRule,
                                    self._make_security_group_rule_dict,
                                    filters=filters, fields=fields,
                                    sorts=sorts,
                                    limit=limit, marker_obj=marker_obj,
                                    page_reverse=page_reverse)

    def get_security_group_rules_count(self, context, filters=None):
        return self._get_collection_count(context, SecurityGroupRule,
                                          filters=filters)

    def get_security_group_rule(self, context, id, fields=None):
        security_group_rule = self._get_security_group_rule(context, id)
        return self._make_security_group_rule_dict(security_group_rule, fields)

    def _get_security_group_rule(self, context, id):
        try:
            query = self._model_query(context, SecurityGroupRule)
            sgr = query.filter(SecurityGroupRule.id == id).one()
        except exc.NoResultFound:
            raise ext_sg.SecurityGroupRuleNotFound(id=id)
        return sgr

    def delete_security_group_rule(self, context, id):
        kwargs = {
            'context': context,
            'security_group_rule_id': id
        }
        # NOTE(armax): a callback exception here will prevent the request
        # from being processed. This is a hook point for backend's validation;
        # we raise to propagate the reason for the failure.
        try:
            registry.notify(
                resources.SECURITY_GROUP_RULE, events.BEFORE_DELETE, self,
                **kwargs)
        except exceptions.CallbackFailure as e:
            reason = _('cannot be deleted due to %s') % e
            raise ext_sg.SecurityGroupRuleInUse(id=id, reason=reason)

        with context.session.begin(subtransactions=True):
            query = self._model_query(context, SecurityGroupRule).filter(
                SecurityGroupRule.id == id)
            try:
                # As there is a filter on a primary key it is not possible for
                # MultipleResultsFound to be raised
                context.session.delete(query.one())
            except exc.NoResultFound:
                raise ext_sg.SecurityGroupRuleNotFound(id=id)

        registry.notify(
            resources.SECURITY_GROUP_RULE, events.AFTER_DELETE, self,
            **kwargs)

    def _extend_port_dict_security_group(self, port_res, port_db):
        # Security group bindings will be retrieved from the sqlalchemy
        # model. As they're loaded eagerly with ports because of the
        # joined load they will not cause an extra query.
        security_group_ids = [sec_group_mapping['security_group_id'] for
                              sec_group_mapping in port_db.security_groups]
        port_res[ext_sg.SECURITYGROUPS] = security_group_ids
        return port_res

    # Register dict extend functions for ports
    db_base_plugin_v2.NeutronDbPluginV2.register_dict_extend_funcs(
        attributes.PORTS, ['_extend_port_dict_security_group'])

    def _process_port_create_security_group(self, context, port,
                                            security_group_ids):
        if attributes.is_attr_set(security_group_ids):
            for security_group_id in security_group_ids:
                self._create_port_security_group_binding(context, port['id'],
                                                         security_group_id)
        # Convert to list as a set might be passed here and
        # this has to be serialized
        port[ext_sg.SECURITYGROUPS] = (security_group_ids and
                                       list(security_group_ids) or [])

    def _ensure_default_security_group(self, context, tenant_id):
        """Create a default security group if one doesn't exist.

        :returns: the default security group id for given tenant.
        """
        # Make no more than two attempts
        for attempts in (1, 2):
            try:
                query = self._model_query(context, DefaultSecurityGroup)
                default_group = query.filter_by(tenant_id=tenant_id).one()
                return default_group['security_group_id']
            except exc.NoResultFound as ex:
                if attempts > 1:
                    # the second iteration means that attempt to add default
                    # group failed with duplicate error. Since we're still
                    # not seeing this group we're most probably inside a
                    # transaction with REPEATABLE READ isolation level ->
                    # need to restart the whole transaction
                    raise db_exc.RetryRequest(ex)

                security_group = {
                    'security_group':
                        {'name': 'default',
                         'tenant_id': tenant_id,
                         'description': _('Default security group')}
                }
                try:
                    security_group = self.create_security_group(
                        context, security_group, default_sg=True)
                    return security_group['id']
                except db_exc.DBDuplicateEntry as ex:
                    # default security group was created concurrently
                    LOG.debug("Duplicate default security group %s was "
                              "not created", ex.value)

    def _get_security_groups_on_port(self, context, port):
        """Check that all security groups on port belong to tenant.

        :returns: all security groups IDs on port belonging to tenant.
        """
        port = port['port']
        if not attributes.is_attr_set(port.get(ext_sg.SECURITYGROUPS)):
            return
        if port.get('device_owner') and utils.is_port_trusted(port):
            return

        port_sg = port.get(ext_sg.SECURITYGROUPS, [])
        filters = {'id': port_sg}
        tenant_id = port.get('tenant_id')
        if tenant_id:
            filters['tenant_id'] = [tenant_id]
        valid_groups = set(g['id'] for g in
                           self.get_security_groups(context, fields=['id'],
                                                    filters=filters))

        requested_groups = set(port_sg)
        port_sg_missing = requested_groups - valid_groups
        if port_sg_missing:
            raise ext_sg.SecurityGroupNotFound(id=', '.join(port_sg_missing))

        return requested_groups

    def _ensure_default_security_group_on_port(self, context, port):
        # we don't apply security groups for dhcp, router
        port = port['port']
        if port.get('device_owner') and utils.is_port_trusted(port):
            return
        tenant_id = self._get_tenant_id_for_create(context, port)
        default_sg = self._ensure_default_security_group(context, tenant_id)
        if not attributes.is_attr_set(port.get(ext_sg.SECURITYGROUPS)):
            port[ext_sg.SECURITYGROUPS] = [default_sg]

    def _check_update_deletes_security_groups(self, port):
        """Return True if port has as a security group and it's value
        is either [] or not is_attr_set, otherwise return False
        """
        if (ext_sg.SECURITYGROUPS in port['port'] and
            not (attributes.is_attr_set(port['port'][ext_sg.SECURITYGROUPS])
                 and port['port'][ext_sg.SECURITYGROUPS] != [])):
            return True
        return False

    def _check_update_has_security_groups(self, port):
        """Return True if port has security_groups attribute set and
        its not empty, or False otherwise.
        This method is called both for port create and port update.
        """
        if (ext_sg.SECURITYGROUPS in port['port'] and
            (attributes.is_attr_set(port['port'][ext_sg.SECURITYGROUPS]) and
             port['port'][ext_sg.SECURITYGROUPS] != [])):
            return True
        return False

    def update_security_group_on_port(self, context, id, port,
                                      original_port, updated_port):
        """Update security groups on port.

        This method returns a flag which indicates request notification
        is required and does not perform notification itself.
        It is because another changes for the port may require notification.
        """
        need_notify = False
        port_updates = port['port']
        if (ext_sg.SECURITYGROUPS in port_updates and
            not utils.compare_elements(
                original_port.get(ext_sg.SECURITYGROUPS),
                port_updates[ext_sg.SECURITYGROUPS])):
            # delete the port binding and read it with the new rules
            port_updates[ext_sg.SECURITYGROUPS] = (
                self._get_security_groups_on_port(context, port))
            self._delete_port_security_group_bindings(context, id)
            self._process_port_create_security_group(
                context,
                updated_port,
                port_updates[ext_sg.SECURITYGROUPS])
            need_notify = True
        else:
            updated_port[ext_sg.SECURITYGROUPS] = (
                original_port[ext_sg.SECURITYGROUPS])
        return need_notify
