def create_subnet(context, subnet):
    """Create a subnet.

    Create a subnet which represents a range of IP addresses
    that can be allocated to devices

    : param context: neutron api request context
    : param subnet: dictionary describing the subnet, with keys
        as listed in the RESOURCE_ATTRIBUTE_MAP object in
        neutron/api/v2/attributes.py.  All keys will be populated.
    """
    LOG.info("create_subnet for tenant %s" % context.tenant_id)
    net_id = subnet["subnet"]["network_id"]

    net = db_api.network_find(context, id=net_id, scope=db_api.ONE)
    if not net:
        raise exceptions.NetworkNotFound(net_id=net_id)

    sub_attrs = subnet["subnet"]

    _validate_subnet_cidr(context, net_id, sub_attrs["cidr"])

    cidr = netaddr.IPNetwork(sub_attrs["cidr"])
    gateway_ip = utils.pop_param(sub_attrs, "gateway_ip", str(cidr[1]))
    dns_ips = utils.pop_param(sub_attrs, "dns_nameservers", [])
    host_routes = utils.pop_param(sub_attrs, "host_routes", [])
    allocation_pools = utils.pop_param(sub_attrs, "allocation_pools", [])
    sub_attrs["network"] = net

    new_subnet = db_api.subnet_create(context, **sub_attrs)

    default_route = None
    for route in host_routes:
        netaddr_route = netaddr.IPNetwork(route["destination"])
        if netaddr_route.value == routes.DEFAULT_ROUTE.value:
            default_route = route
            gateway_ip = default_route["nexthop"]
        new_subnet["routes"].append(db_api.route_create(
            context, cidr=route["destination"], gateway=route["nexthop"]))

    if default_route is None:
        new_subnet["routes"].append(db_api.route_create(
            context, cidr=str(routes.DEFAULT_ROUTE), gateway=gateway_ip))

    for dns_ip in dns_ips:
        new_subnet["dns_nameservers"].append(db_api.dns_create(
            context, ip=netaddr.IPAddress(dns_ip)))

    if allocation_pools:
        exclude = netaddr.IPSet([cidr])
        for p in allocation_pools:
            x = netaddr.IPSet(netaddr.IPRange(p["start"], p["end"]))
            exclude = exclude - x
        new_subnet["ip_policy"] = db_api.ip_policy_create(context,
                                                          exclude=exclude)
    subnet_dict = v._make_subnet_dict(new_subnet,
                                      default_route=routes.DEFAULT_ROUTE)
    subnet_dict["gateway_ip"] = gateway_ip
    return subnet_dict

def _adapt_provider_nets(context, network):
    # TODO(mdietz) going to ignore all the boundary and network
    #             type checking for now.
    attrs = network["network"]
    net_type = utils.pop_param(attrs, pnet.NETWORK_TYPE)
    phys_net = utils.pop_param(attrs, pnet.PHYSICAL_NETWORK)
    seg_id = utils.pop_param(attrs, pnet.SEGMENTATION_ID)
    return net_type, phys_net, seg_id

def update_network(context, id, network):
    """Update values of a network.

    : param context: neutron api request context
    : param id: UUID representing the network to update.
    : param network: dictionary with keys indicating fields to update.
        valid keys are those that have a value of True for 'allow_put'
        as listed in the RESOURCE_ATTRIBUTE_MAP object in
        neutron/api/v2/attributes.py.
    """
    LOG.info("update_network %s for tenant %s" %
             (id, context.tenant_id))
    with context.session.begin():
        net = db_api.network_find(context, id=id, scope=db_api.ONE)
        if not net:
            raise exceptions.NetworkNotFound(net_id=id)
        net_dict = network["network"]
        utils.pop_param(net_dict, "network_plugin")
        if not context.is_admin and "ipam_strategy" in net_dict:
            utils.pop_param(net_dict, "ipam_strategy")
        net = db_api.network_update(context, net, **net_dict)

    return v._make_network_dict(net)

def create_subnet(context, subnet):
    """Create a subnet.

    Create a subnet which represents a range of IP addresses
    that can be allocated to devices

    : param context: neutron api request context
    : param subnet: dictionary describing the subnet, with keys
        as listed in the RESOURCE_ATTRIBUTE_MAP object in
        neutron/api/v2/attributes.py.  All keys will be populated.
    """
    LOG.info("create_subnet for tenant %s" % context.tenant_id)
    net_id = subnet["subnet"]["network_id"]

    with context.session.begin():
        net = db_api.network_find(context, id=net_id, scope=db_api.ONE)
        if not net:
            raise exceptions.NetworkNotFound(net_id=net_id)

        sub_attrs = subnet["subnet"]

        _validate_subnet_cidr(context, net_id, sub_attrs["cidr"])

        cidr = netaddr.IPNetwork(sub_attrs["cidr"])

        err_vals = {'cidr': sub_attrs["cidr"], 'network_id': net_id}
        err = _("Requested subnet with cidr: %(cidr)s for "
                "network: %(network_id)s. Prefix is too small, must be a "
                "larger subnet. A prefix less than /%(prefix)s is required.")

        if cidr.version == 6 and cidr.prefixlen > 64:
            err_vals["prefix"] = 65
            err_msg = err % err_vals
            raise exceptions.InvalidInput(error_message=err_msg)
        elif cidr.version == 4 and cidr.prefixlen > 30:
            err_vals["prefix"] = 31
            err_msg = err % err_vals
            raise exceptions.InvalidInput(error_message=err_msg)

        gateway_ip = utils.pop_param(sub_attrs, "gateway_ip", str(cidr[1]))
        dns_ips = utils.pop_param(sub_attrs, "dns_nameservers", [])
        host_routes = utils.pop_param(sub_attrs, "host_routes", [])
        allocation_pools = utils.pop_param(sub_attrs, "allocation_pools", None)

        if not context.is_admin and "segment_id" in sub_attrs:
            sub_attrs.pop("segment_id")

        sub_attrs["network"] = net

        new_subnet = db_api.subnet_create(context, **sub_attrs)

        default_route = None
        for route in host_routes:
            netaddr_route = netaddr.IPNetwork(route["destination"])
            if netaddr_route.value == routes.DEFAULT_ROUTE.value:
                if default_route:
                    raise q_exc.DuplicateRouteConflict(
                        subnet_id=new_subnet["id"])

                default_route = route
                gateway_ip = default_route["nexthop"]
            new_subnet["routes"].append(db_api.route_create(
                context, cidr=route["destination"], gateway=route["nexthop"]))

        if gateway_ip and default_route is None:
            new_subnet["routes"].append(db_api.route_create(
                context, cidr=str(routes.DEFAULT_ROUTE), gateway=gateway_ip))

        for dns_ip in dns_ips:
            new_subnet["dns_nameservers"].append(db_api.dns_create(
                context, ip=netaddr.IPAddress(dns_ip)))

        if isinstance(allocation_pools, list) and allocation_pools:
            subnet_net = netaddr.IPNetwork(new_subnet["cidr"])
            cidrset = netaddr.IPSet(
                netaddr.IPRange(
                    netaddr.IPAddress(subnet_net.first),
                    netaddr.IPAddress(subnet_net.last)).cidrs())
            for p in allocation_pools:
                start = netaddr.IPAddress(p["start"])
                end = netaddr.IPAddress(p["end"])
                cidrset -= netaddr.IPSet(netaddr.IPRange(
                    netaddr.IPAddress(start),
                    netaddr.IPAddress(end)).cidrs())
            default_cidrset = models.IPPolicy.get_ip_policy_cidrs(new_subnet)
            cidrset.update(default_cidrset)
            cidrs = [str(x.cidr) for x in cidrset.iter_cidrs()]
            new_subnet["ip_policy"] = db_api.ip_policy_create(context,
                                                              exclude=cidrs)

    subnet_dict = v._make_subnet_dict(new_subnet)
    subnet_dict["gateway_ip"] = gateway_ip

    notifier_api.notify(context,
                        notifier_api.publisher_id("network"),
                        "ip_block.create",
                        notifier_api.CONF.default_notification_level,
                        dict(tenant_id=subnet_dict["tenant_id"],
                             ip_block_id=subnet_dict["id"],
                             created_at=new_subnet["created_at"]))
#.........这里部分代码省略.........

def create_subnet(context, subnet):
    """Create a subnet.

    Create a subnet which represents a range of IP addresses
    that can be allocated to devices

    : param context: neutron api request context
    : param subnet: dictionary describing the subnet, with keys
        as listed in the RESOURCE_ATTRIBUTE_MAP object in
        neutron/api/v2/attributes.py.  All keys will be populated.
    """
    LOG.info("create_subnet for tenant %s" % context.tenant_id)
    net_id = subnet["subnet"]["network_id"]

    with context.session.begin():
        net = db_api.network_find(context, None, None, None, False,
                                  id=net_id, scope=db_api.ONE)
        if not net:
            raise exceptions.NetworkNotFound(net_id=net_id)

        sub_attrs = subnet["subnet"]

        always_pop = ["enable_dhcp", "ip_version", "first_ip", "last_ip",
                      "_cidr"]
        admin_only = ["segment_id", "do_not_use", "created_at",
                      "next_auto_assign_ip"]
        utils.filter_body(context, sub_attrs, admin_only, always_pop)

        _validate_subnet_cidr(context, net_id, sub_attrs["cidr"])

        cidr = netaddr.IPNetwork(sub_attrs["cidr"])

        err_vals = {'cidr': sub_attrs["cidr"], 'network_id': net_id}
        err = _("Requested subnet with cidr: %(cidr)s for "
                "network: %(network_id)s. Prefix is too small, must be a "
                "larger subnet. A prefix less than /%(prefix)s is required.")

        if cidr.version == 6 and cidr.prefixlen > 64:
            err_vals["prefix"] = 65
            err_msg = err % err_vals
            raise exceptions.InvalidInput(error_message=err_msg)
        elif cidr.version == 4 and cidr.prefixlen > 30:
            err_vals["prefix"] = 31
            err_msg = err % err_vals
            raise exceptions.InvalidInput(error_message=err_msg)
        # Enforce subnet quotas
        net_subnets = get_subnets(context,
                                  filters=dict(network_id=net_id))
        if not context.is_admin:
            v4_count, v6_count = 0, 0
            for subnet in net_subnets:
                if netaddr.IPNetwork(subnet['cidr']).version == 6:
                    v6_count += 1
                else:
                    v4_count += 1

            if cidr.version == 6:
                tenant_quota_v6 = context.session.query(qdv.Quota).filter_by(
                    tenant_id=context.tenant_id,
                    resource='v6_subnets_per_network').first()
                if tenant_quota_v6 != -1:
                    quota.QUOTAS.limit_check(
                        context, context.tenant_id,
                        v6_subnets_per_network=v6_count + 1)
            else:
                tenant_quota_v4 = context.session.query(qdv.Quota).filter_by(
                    tenant_id=context.tenant_id,
                    resource='v4_subnets_per_network').first()
                if tenant_quota_v4 != -1:
                    quota.QUOTAS.limit_check(
                        context, context.tenant_id,
                        v4_subnets_per_network=v4_count + 1)

        # See RM981. The default behavior of setting a gateway unless
        # explicitly asked to not is no longer desirable.
        gateway_ip = utils.pop_param(sub_attrs, "gateway_ip")
        dns_ips = utils.pop_param(sub_attrs, "dns_nameservers", [])
        host_routes = utils.pop_param(sub_attrs, "host_routes", [])
        allocation_pools = utils.pop_param(sub_attrs, "allocation_pools", None)

        sub_attrs["network"] = net
        new_subnet = db_api.subnet_create(context, **sub_attrs)

        cidrs = []
        alloc_pools = allocation_pool.AllocationPools(sub_attrs["cidr"],
                                                      allocation_pools)
        if isinstance(allocation_pools, list):
            cidrs = alloc_pools.get_policy_cidrs()

        quota.QUOTAS.limit_check(
            context,
            context.tenant_id,
            alloc_pools_per_subnet=len(alloc_pools))

        ip_policies.ensure_default_policy(cidrs, [new_subnet])
        new_subnet["ip_policy"] = db_api.ip_policy_create(context,
                                                          exclude=cidrs)

        quota.QUOTAS.limit_check(context, context.tenant_id,
                                 routes_per_subnet=len(host_routes))
#.........这里部分代码省略.........

def update_subnet(context, id, subnet):
    """Update values of a subnet.

    : param context: neutron api request context
    : param id: UUID representing the subnet to update.
    : param subnet: dictionary with keys indicating fields to update.
        valid keys are those that have a value of True for 'allow_put'
        as listed in the RESOURCE_ATTRIBUTE_MAP object in
        neutron/api/v2/attributes.py.
    """
    LOG.info("update_subnet %s for tenant %s" %
             (id, context.tenant_id))

    with context.session.begin():
        subnet_db = db_api.subnet_find(context, None, None, None, False, id=id,
                                       scope=db_api.ONE)
        if not subnet_db:
            raise exceptions.SubnetNotFound(id=id)

        s = subnet["subnet"]
        always_pop = ["_cidr", "cidr", "first_ip", "last_ip", "ip_version",
                      "segment_id", "network_id"]
        admin_only = ["do_not_use", "created_at", "tenant_id",
                      "next_auto_assign_ip", "enable_dhcp"]
        utils.filter_body(context, s, admin_only, always_pop)

        dns_ips = utils.pop_param(s, "dns_nameservers", [])
        host_routes = utils.pop_param(s, "host_routes", [])
        gateway_ip = utils.pop_param(s, "gateway_ip", None)
        allocation_pools = utils.pop_param(s, "allocation_pools", None)
        if not CONF.QUARK.allow_allocation_pool_update:
            if allocation_pools:
                raise exceptions.BadRequest(
                    resource="subnets",
                    msg="Allocation pools cannot be updated.")
            alloc_pools = allocation_pool.AllocationPools(
                subnet_db["cidr"],
                policies=models.IPPolicy.get_ip_policy_cidrs(subnet_db))
        else:
            alloc_pools = allocation_pool.AllocationPools(subnet_db["cidr"],
                                                          allocation_pools)

        quota.QUOTAS.limit_check(
            context,
            context.tenant_id,
            alloc_pools_per_subnet=len(alloc_pools))
        if gateway_ip:
            alloc_pools.validate_gateway_excluded(gateway_ip)
            default_route = None
            for route in host_routes:
                netaddr_route = netaddr.IPNetwork(route["destination"])
                if netaddr_route.value == routes.DEFAULT_ROUTE.value:
                    default_route = route
                    break

            if default_route is None:
                route_model = db_api.route_find(
                    context, cidr=str(routes.DEFAULT_ROUTE), subnet_id=id,
                    scope=db_api.ONE)
                if route_model:
                    db_api.route_update(context, route_model,
                                        gateway=gateway_ip)
                else:
                    db_api.route_create(context,
                                        cidr=str(routes.DEFAULT_ROUTE),
                                        gateway=gateway_ip, subnet_id=id)

        if dns_ips:
            subnet_db["dns_nameservers"] = []
            quota.QUOTAS.limit_check(context, context.tenant_id,
                                     dns_nameservers_per_subnet=len(dns_ips))

        for dns_ip in dns_ips:
            subnet_db["dns_nameservers"].append(db_api.dns_create(
                context,
                ip=netaddr.IPAddress(dns_ip)))

        if host_routes:
            subnet_db["routes"] = []
            quota.QUOTAS.limit_check(context, context.tenant_id,
                                     routes_per_subnet=len(host_routes))

        for route in host_routes:
            subnet_db["routes"].append(db_api.route_create(
                context, cidr=route["destination"], gateway=route["nexthop"]))
        if CONF.QUARK.allow_allocation_pool_update:
            if isinstance(allocation_pools, list):
                cidrs = alloc_pools.get_policy_cidrs()
                ip_policies.ensure_default_policy(cidrs, [subnet_db])
                subnet_db["ip_policy"] = db_api.ip_policy_update(
                    context, subnet_db["ip_policy"], exclude=cidrs)
                # invalidate the cache
                db_api.subnet_update_set_alloc_pool_cache(context, subnet_db)
        subnet = db_api.subnet_update(context, subnet_db, **s)
    return v._make_subnet_dict(subnet)

def create_port(context, port):
    """Create a port

    Create a port which is a connection point of a device (e.g., a VM
    NIC) to attach to a L2 Neutron network.
    : param context: neutron api request context
    : param port: dictionary describing the port, with keys
        as listed in the RESOURCE_ATTRIBUTE_MAP object in
        neutron/api/v2/attributes.py.  All keys will be populated.
    """
    LOG.info("create_port for tenant %s" % context.tenant_id)
    port_attrs = port["port"]

    admin_only = ["mac_address", "device_owner", "bridge", "admin_state_up",
                  "use_forbidden_mac_range"]
    utils.filter_body(context, port_attrs, admin_only=admin_only)

    port_attrs = port["port"]
    mac_address = utils.pop_param(port_attrs, "mac_address", None)
    use_forbidden_mac_range = utils.pop_param(port_attrs,
                                              "use_forbidden_mac_range", False)
    segment_id = utils.pop_param(port_attrs, "segment_id")
    fixed_ips = utils.pop_param(port_attrs, "fixed_ips")
    if "device_id" not in port_attrs:
        port_attrs['device_id'] = ""
    device_id = port_attrs['device_id']
    net_id = port_attrs["network_id"]

    port_id = uuidutils.generate_uuid()

    net = db_api.network_find(context, None, None, None, False, id=net_id,
                              scope=db_api.ONE)

    if not net:
        raise exceptions.NetworkNotFound(net_id=net_id)
    _raise_if_unauthorized(context.tenant_id, net)

    # NOTE (Perkins): If a device_id is given, try to prevent multiple ports
    # from being created for a device already attached to the network
    if device_id:
        existing_ports = db_api.port_find(context,
                                          network_id=net_id,
                                          device_id=device_id,
                                          scope=db_api.ONE)
        if existing_ports:
            raise exceptions.BadRequest(
                resource="port", msg="This device is already connected to the "
                "requested network via another port")

    # Try to fail early on quotas and save ourselves some db overhead
    if fixed_ips:
        quota.QUOTAS.limit_check(context, context.tenant_id,
                                 fixed_ips_per_port=len(fixed_ips))

    if not STRATEGY.is_parent_network(net_id):
        # We don't honor segmented networks when they aren't "shared"
        segment_id = None
        port_count = db_api.port_count_all(context, network_id=[net_id],
                                           tenant_id=[context.tenant_id])
        quota.QUOTAS.limit_check(
            context, context.tenant_id,
            ports_per_network=port_count + 1)
    else:
        if not segment_id:
            raise q_exc.AmbiguousNetworkId(net_id=net_id)

    ipam_driver = ipam.IPAM_REGISTRY.get_strategy(net["ipam_strategy"])

    net_driver = registry.DRIVER_REGISTRY.get_driver(net["network_plugin"])

    # TODO(anyone): security groups are not currently supported on port create,
    #               nor on isolated networks today. Please see RM8615
    security_groups = utils.pop_param(port_attrs, "security_groups")
    if security_groups is not None:
        raise q_exc.SecurityGroupsNotImplemented()

    group_ids, security_groups = _make_security_group_list(context,
                                                           security_groups)
    quota.QUOTAS.limit_check(context, context.tenant_id,
                             security_groups_per_port=len(group_ids))
    addresses = []
    backend_port = None

    with utils.CommandManager().execute() as cmd_mgr:
        @cmd_mgr.do
        def _allocate_ips(fixed_ips, net, port_id, segment_id, mac):
            fixed_ip_kwargs = {}
            if fixed_ips:
                if STRATEGY.is_parent_network(net_id) and not context.is_admin:
                    raise exceptions.NotAuthorized()

                ips, subnets = split_and_validate_requested_subnets(context,
                                                                    net_id,
                                                                    segment_id,
                                                                    fixed_ips)
                fixed_ip_kwargs["ip_addresses"] = ips
                fixed_ip_kwargs["subnets"] = subnets

            ipam_driver.allocate_ip_address(
                context, addresses, net["id"], port_id,
#.........这里部分代码省略.........

def update_port(context, id, port):
    """Update values of a port.

    : param context: neutron api request context
    : param id: UUID representing the port to update.
    : param port: dictionary with keys indicating fields to update.
        valid keys are those that have a value of True for 'allow_put'
        as listed in the RESOURCE_ATTRIBUTE_MAP object in
        neutron/api/v2/attributes.py.
    """
    LOG.info("update_port %s for tenant %s" % (id, context.tenant_id))
    port_db = db_api.port_find(context, id=id, scope=db_api.ONE)
    if not port_db:
        raise exceptions.PortNotFound(port_id=id)

    port_dict = port["port"]
    fixed_ips = port_dict.pop("fixed_ips", None)

    admin_only = ["mac_address", "device_owner", "bridge", "admin_state_up",
                  "device_id"]
    always_filter = ["network_id", "backend_key"]
    utils.filter_body(context, port_dict, admin_only=admin_only,
                      always_filter=always_filter)

    # Pre-check the requested fixed_ips before making too many db trips.
    # Note that this is the only check we need, since this call replaces
    # the entirety of the IP addresses document if fixed_ips are provided.
    if fixed_ips:
        quota.QUOTAS.limit_check(context, context.tenant_id,
                                 fixed_ips_per_port=len(fixed_ips))

    # TODO(anyone): security groups are not currently supported on port create,
    #               nor on isolated networks today. Please see RM8615
    new_security_groups = utils.pop_param(port_dict, "security_groups")
    if new_security_groups is not None:
        if not STRATEGY.is_parent_network(port_db["network_id"]):
            raise q_exc.TenantNetworkSecurityGroupsNotImplemented()

    if new_security_groups is not None and not port_db["device_id"]:
        raise q_exc.SecurityGroupsRequireDevice()

    group_ids, security_group_mods = _make_security_group_list(
        context, new_security_groups)
    quota.QUOTAS.limit_check(context, context.tenant_id,
                             security_groups_per_port=len(group_ids))

    if fixed_ips is not None:
        # NOTE(mdietz): we want full control over IPAM since
        #              we're allocating by subnet instead of
        #              network.
        ipam_driver = ipam.IPAM_REGISTRY.get_strategy(
            ipam.QuarkIpamANY.get_name())

        addresses, subnet_ids = [], []
        ip_addresses = {}

        for fixed_ip in fixed_ips:
            subnet_id = fixed_ip.get("subnet_id")
            ip_address = fixed_ip.get("ip_address")
            if not (subnet_id or ip_address):
                raise exceptions.BadRequest(
                    resource="fixed_ips",
                    msg="subnet_id or ip_address required")

            if ip_address and not subnet_id:
                raise exceptions.BadRequest(
                    resource="fixed_ips",
                    msg="subnet_id required for ip_address allocation")

            if subnet_id and ip_address:
                ip_netaddr = netaddr.IPAddress(ip_address).ipv6()
                ip_addresses[ip_netaddr] = subnet_id
            else:
                subnet_ids.append(subnet_id)

        port_ips = set([netaddr.IPAddress(int(a["address"]))
                        for a in port_db["ip_addresses"]])
        new_ips = set([a for a in ip_addresses.keys()])

        ips_to_allocate = list(new_ips - port_ips)
        ips_to_deallocate = list(port_ips - new_ips)

        for ip in ips_to_allocate:
            if ip in ip_addresses:
                # NOTE: Fix for RM10187 - we were losing the list of IPs if
                #       more than one IP was to be allocated. Track an
                #       aggregate list instead, and add it to the running total
                #       after each allocate
                allocated = []
                ipam_driver.allocate_ip_address(
                    context, allocated, port_db["network_id"],
                    port_db["id"], reuse_after=None, ip_addresses=[ip],
                    subnets=[ip_addresses[ip]])
                addresses.extend(allocated)

        for ip in ips_to_deallocate:
            ipam_driver.deallocate_ips_by_port(
                context, port_db, ip_address=ip)

        for subnet_id in subnet_ids:
#.........这里部分代码省略.........

def create_network(context, network):
    """Create a network.

    Create a network which represents an L2 network segment which
    can have a set of subnets and ports associated with it.
    : param context: neutron api request context
    : param network: dictionary describing the network, with keys
        as listed in the RESOURCE_ATTRIBUTE_MAP object in
        neutron/api/v2/attributes.py.  All keys will be populated.
    """
    LOG.info("create_network for tenant %s" % context.tenant_id)

    with context.session.begin():
        net_attrs = network["network"]
        subs = net_attrs.pop("subnets", [])
        # Enforce subnet quotas
        if not context.is_admin:
            if len(subs) > 0:
                v4_count, v6_count = 0, 0
                for s in subs:
                    version = netaddr.IPNetwork(s['subnet']['cidr']).version
                    if version == 6:
                        v6_count += 1
                    else:
                        v4_count += 1
                if v4_count > 0:
                    tenant_q_v4 = context.session.query(qdb.Quota).filter_by(
                        tenant_id=context.tenant_id,
                        resource='v4_subnets_per_network').first()
                    if tenant_q_v4 != -1:
                        quota.QUOTAS.limit_check(
                            context,
                            context.tenant_id,
                            v4_subnets_per_network=v4_count)
                if v6_count > 0:
                    tenant_q_v6 = context.session.query(qdb.Quota).filter_by(
                        tenant_id=context.tenant_id,
                        resource='v6_subnets_per_network').first()
                    if tenant_q_v6 != -1:
                        quota.QUOTAS.limit_check(
                            context,
                            context.tenant_id,
                            v6_subnets_per_network=v6_count)
        # Generate a uuid that we're going to hand to the backend and db
        net_uuid = utils.pop_param(net_attrs, "id", None)
        net_type = None
        if net_uuid and context.is_admin:
            net = db_api.network_find(context, id=net_uuid, scope=db_api.ONE)
            net_type = utils.pop_param(net_attrs, "network_plugin", None)
            if net:
                raise q_exc.NetworkAlreadyExists(id=net_uuid)
        else:
            net_uuid = uuidutils.generate_uuid()

        # TODO(mdietz) this will be the first component registry hook, but
        #             lets make it work first
        pnet_type, phys_net, seg_id = _adapt_provider_nets(context, network)

        ipam_strategy = utils.pop_param(net_attrs, "ipam_strategy", None)
        if not ipam_strategy or not context.is_admin:
            ipam_strategy = CONF.QUARK.default_ipam_strategy

        if not ipam.IPAM_REGISTRY.is_valid_strategy(ipam_strategy):
            raise q_exc.InvalidIpamStrategy(strat=ipam_strategy)
        net_attrs["ipam_strategy"] = ipam_strategy

        # NOTE(mdietz) I think ideally we would create the providernet
        # elsewhere as a separate driver step that could be
        # kept in a plugin and completely removed if desired. We could
        # have a pre-callback/observer on the netdriver create_network
        # that gathers any additional parameters from the network dict

        default_net_type = net_type or CONF.QUARK.default_network_type
        net_driver = registry.DRIVER_REGISTRY.get_driver(default_net_type)
        net_driver.create_network(context, net_attrs["name"],
                                  network_id=net_uuid, phys_type=pnet_type,
                                  phys_net=phys_net, segment_id=seg_id)

        net_attrs["id"] = net_uuid
        net_attrs["tenant_id"] = context.tenant_id
        net_attrs["network_plugin"] = default_net_type
        new_net = db_api.network_create(context, **net_attrs)

        new_subnets = []
        for sub in subs:
            sub["subnet"]["network_id"] = new_net["id"]
            sub["subnet"]["tenant_id"] = context.tenant_id
            s = db_api.subnet_create(context, **sub["subnet"])
            new_subnets.append(s)
        new_net["subnets"] = new_subnets

        # if not security_groups.get_security_groups(
        #        context,
        #        filters={"id": security_groups.DEFAULT_SG_UUID}):
        #    security_groups._create_default_security_group(context)
    return v._make_network_dict(new_net)

def create_port(context, port):
    """Create a port

    Create a port which is a connection point of a device (e.g., a VM
    NIC) to attach to a L2 Neutron network.
    : param context: neutron api request context
    : param port: dictionary describing the port, with keys
        as listed in the RESOURCE_ATTRIBUTE_MAP object in
        neutron/api/v2/attributes.py.  All keys will be populated.
    """
    LOG.info("create_port for tenant %s" % context.tenant_id)

    port_attrs = port["port"]
    mac_address = utils.pop_param(port_attrs, "mac_address", None)
    segment_id = utils.pop_param(port_attrs, "segment_id")
    fixed_ips = utils.pop_param(port_attrs, "fixed_ips")
    net_id = port_attrs["network_id"]
    device_id = port_attrs["device_id"]

    port_id = uuidutils.generate_uuid()

    net = db_api.network_find(context, id=net_id, scope=db_api.ONE)
    if not net:
        raise exceptions.NetworkNotFound(net_id=net_id)

    if not STRATEGY.is_parent_network(net_id):
        # We don't honor segmented networks when they aren't "shared"
        segment_id = None
        port_count = db_api.port_count_all(context, network_id=[net_id],
                                           tenant_id=[context.tenant_id])

        quota.QUOTAS.limit_check(
            context, context.tenant_id,
            ports_per_network=port_count + 1)
    else:
        if not segment_id:
            raise q_exc.AmbiguousNetworkId(net_id=net_id)

    ipam_driver = ipam.IPAM_REGISTRY.get_strategy(net["ipam_strategy"])
    net_driver = registry.DRIVER_REGISTRY.get_driver(net["network_plugin"])
    group_ids, security_groups = v.make_security_group_list(
        context, port["port"].pop("security_groups", None))

    addresses = []
    mac = None
    backend_port = None

    with utils.CommandManager().execute() as cmd_mgr:
        @cmd_mgr.do
        def _allocate_ips(fixed_ips, net, port_id, segment_id, mac):
            if fixed_ips:
                for fixed_ip in fixed_ips:
                    subnet_id = fixed_ip.get("subnet_id")
                    ip_address = fixed_ip.get("ip_address")
                    if not (subnet_id and ip_address):
                        raise exceptions.BadRequest(
                            resource="fixed_ips",
                            msg="subnet_id and ip_address required")
                    ipam_driver.allocate_ip_address(
                        context, addresses, net["id"], port_id,
                        CONF.QUARK.ipam_reuse_after, segment_id=segment_id,
                        ip_address=ip_address, subnets=[subnet_id],
                        mac_address=mac)
            else:
                ipam_driver.allocate_ip_address(
                    context, addresses, net["id"], port_id,
                    CONF.QUARK.ipam_reuse_after, segment_id=segment_id,
                    mac_address=mac)

        @cmd_mgr.undo
        def _allocate_ips_undo(addr):
            LOG.info("Rolling back IP addresses...")
            if addresses:
                for address in addresses:
                    try:
                        with context.session.begin():
                            ipam_driver.deallocate_ip_address(context, address)
                    except Exception:
                        LOG.exception("Couldn't release IP %s" % address)

        @cmd_mgr.do
        def _allocate_mac(net, port_id, mac_address):
            mac = ipam_driver.allocate_mac_address(
                context, net["id"], port_id, CONF.QUARK.ipam_reuse_after,
                mac_address=mac_address)
            return mac

        @cmd_mgr.undo
        def _allocate_mac_undo(mac):
            LOG.info("Rolling back MAC address...")
            if mac:
                try:
                    with context.session.begin():
                        ipam_driver.deallocate_mac_address(context,
                                                           mac["address"])
                except Exception:
                    LOG.exception("Couldn't release MAC %s" % mac)

        @cmd_mgr.do
        def _allocate_backend_port(mac, addresses, net, port_id):
#.........这里部分代码省略.........

def create_subnet(context, subnet):
    """Create a subnet.

    Create a subnet which represents a range of IP addresses
    that can be allocated to devices

    : param context: neutron api request context
    : param subnet: dictionary describing the subnet, with keys
        as listed in the RESOURCE_ATTRIBUTE_MAP object in
        neutron/api/v2/attributes.py.  All keys will be populated.
    """
    LOG.info("create_subnet for tenant %s" % context.tenant_id)
    net_id = subnet["subnet"]["network_id"]

    with context.session.begin():
        net = db_api.network_find(context, id=net_id, scope=db_api.ONE)
        if not net:
            raise exceptions.NetworkNotFound(net_id=net_id)

        sub_attrs = subnet["subnet"]

        _validate_subnet_cidr(context, net_id, sub_attrs["cidr"])

        cidr = netaddr.IPNetwork(sub_attrs["cidr"])
        gateway_ip = utils.pop_param(sub_attrs, "gateway_ip", str(cidr[1]))
        dns_ips = utils.pop_param(sub_attrs, "dns_nameservers", [])
        host_routes = utils.pop_param(sub_attrs, "host_routes", [])
        allocation_pools = utils.pop_param(sub_attrs, "allocation_pools", None)
        sub_attrs["network"] = net

        new_subnet = db_api.subnet_create(context, **sub_attrs)

        default_route = None
        for route in host_routes:
            netaddr_route = netaddr.IPNetwork(route["destination"])
            if netaddr_route.value == routes.DEFAULT_ROUTE.value:
                default_route = route
                gateway_ip = default_route["nexthop"]
            new_subnet["routes"].append(db_api.route_create(
                context, cidr=route["destination"], gateway=route["nexthop"]))

        if default_route is None:
            new_subnet["routes"].append(db_api.route_create(
                context, cidr=str(routes.DEFAULT_ROUTE), gateway=gateway_ip))

        for dns_ip in dns_ips:
            new_subnet["dns_nameservers"].append(db_api.dns_create(
                context, ip=netaddr.IPAddress(dns_ip)))

        if isinstance(allocation_pools, list):
            ranges = []
            cidrset = netaddr.IPSet([netaddr.IPNetwork(new_subnet["cidr"])])
            for p in allocation_pools:
                cidrset -= netaddr.IPSet(netaddr.IPRange(p["start"], p["end"]))
            non_allocation_pools = v._pools_from_cidr(cidrset)
            for p in non_allocation_pools:
                r = netaddr.IPRange(p["start"], p["end"])
                ranges.append(dict(
                    length=len(r),
                    offset=int(r[0]) - int(cidr[0])))
            new_subnet["ip_policy"] = db_api.ip_policy_create(context,
                                                              exclude=ranges)

    subnet_dict = v._make_subnet_dict(new_subnet,
                                      default_route=routes.DEFAULT_ROUTE)
    subnet_dict["gateway_ip"] = gateway_ip

    notifier_api.notify(context,
                        notifier_api.publisher_id("network"),
                        "ip_block.create",
                        notifier_api.CONF.default_notification_level,
                        dict(tenant_id=subnet_dict["tenant_id"],
                             ip_block_id=subnet_dict["id"],
                             created_at=new_subnet["created_at"]))

    return subnet_dict

def create_port(context, port):
    """Create a port

    Create a port which is a connection point of a device (e.g., a VM
    NIC) to attach to a L2 Neutron network.
    : param context: neutron api request context
    : param port: dictionary describing the port, with keys
        as listed in the RESOURCE_ATTRIBUTE_MAP object in
        neutron/api/v2/attributes.py.  All keys will be populated.
    """
    LOG.info("create_port for tenant %s" % context.tenant_id)

    port_attrs = port["port"]
    mac_address = utils.pop_param(port_attrs, "mac_address", None)
    segment_id = utils.pop_param(port_attrs, "segment_id")
    fixed_ips = utils.pop_param(port_attrs, "fixed_ips")
    net_id = port_attrs["network_id"]
    addresses = []

    with context.session.begin():
        port_id = uuidutils.generate_uuid()

        net = db_api.network_find(context, id=net_id, segment_id=segment_id, scope=db_api.ONE)
        if not net:
            # Maybe it's a tenant network
            net = db_api.network_find(context, id=net_id, scope=db_api.ONE)
            if not net:
                raise exceptions.NetworkNotFound(net_id=net_id)

        if not STRATEGY.is_parent_network(net_id):
            quota.QUOTAS.limit_check(context, context.tenant_id, ports_per_network=len(net.get("ports", [])) + 1)

        ipam_driver = ipam.IPAM_REGISTRY.get_strategy(net["ipam_strategy"])
        if fixed_ips:
            for fixed_ip in fixed_ips:
                subnet_id = fixed_ip.get("subnet_id")
                ip_address = fixed_ip.get("ip_address")
                if not (subnet_id and ip_address):
                    raise exceptions.BadRequest(resource="fixed_ips", msg="subnet_id and ip_address required")
                addresses.extend(
                    ipam_driver.allocate_ip_address(
                        context, net["id"], port_id, CONF.QUARK.ipam_reuse_after, ip_address=ip_address
                    )
                )
        else:
            addresses.extend(ipam_driver.allocate_ip_address(context, net["id"], port_id, CONF.QUARK.ipam_reuse_after))

        group_ids, security_groups = v.make_security_group_list(context, port["port"].pop("security_groups", None))
        mac = ipam_driver.allocate_mac_address(
            context, net["id"], port_id, CONF.QUARK.ipam_reuse_after, mac_address=mac_address
        )
        mac_address_string = str(netaddr.EUI(mac["address"], dialect=netaddr.mac_unix))
        address_pairs = [
            {"mac_address": mac_address_string, "ip_address": address.get("address_readable", "")}
            for address in addresses
        ]
        net_driver = registry.DRIVER_REGISTRY.get_driver(net["network_plugin"])
        backend_port = net_driver.create_port(
            context, net["id"], port_id=port_id, security_groups=group_ids, allowed_pairs=address_pairs
        )

        port_attrs["network_id"] = net["id"]
        port_attrs["id"] = port_id
        port_attrs["security_groups"] = security_groups

        LOG.info("Including extra plugin attrs: %s" % backend_port)
        port_attrs.update(backend_port)
        new_port = db_api.port_create(
            context, addresses=addresses, mac_address=mac["address"], backend_key=backend_port["uuid"], **port_attrs
        )

        # Include any driver specific bits
    return v._make_port_dict(new_port)

def create_port(context, port):
    """Create a port

    Create a port which is a connection point of a device (e.g., a VM
    NIC) to attach to a L2 Neutron network.
    : param context: neutron api request context
    : param port: dictionary describing the port, with keys
        as listed in the RESOURCE_ATTRIBUTE_MAP object in
        neutron/api/v2/attributes.py.  All keys will be populated.
    """
    LOG.info("create_port for tenant %s" % context.tenant_id)

    port_attrs = port["port"]
    mac_address = utils.pop_param(port_attrs, "mac_address", None)
    segment_id = utils.pop_param(port_attrs, "segment_id")
    fixed_ips = utils.pop_param(port_attrs, "fixed_ips")
    net_id = port_attrs["network_id"]
    addresses = []

    port_id = uuidutils.generate_uuid()

    net = db_api.network_find(context, id=net_id, shared=True,
                              segment_id=segment_id, scope=db_api.ONE)
    if not net:
        # Maybe it's a tenant network
        net = db_api.network_find(context, id=net_id, scope=db_api.ONE)
        if not net:
            raise exceptions.NetworkNotFound(net_id=net_id)

    quota.QUOTAS.limit_check(
        context, context.tenant_id,
        ports_per_network=len(net.get('ports', [])) + 1)

    if fixed_ips:
        for fixed_ip in fixed_ips:
            subnet_id = fixed_ip.get("subnet_id")
            ip_address = fixed_ip.get("ip_address")
            if not (subnet_id and ip_address):
                raise exceptions.BadRequest(
                    resource="fixed_ips",
                    msg="subnet_id and ip_address required")
            addresses.append(ipam_driver.allocate_ip_address(
                context, net["id"], port_id, CONF.QUARK.ipam_reuse_after,