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// Copyright 2018 Google LLC. 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.
package expr
import (
"encoding/binary"
"fmt"
"github.com/google/nftables/binaryutil"
"github.com/mdlayher/netlink"
"golang.org/x/sys/unix"
)
// Numgen defines Numgen expression structure
type Numgen struct {
Register uint32
Modulus uint32
Type uint32
Offset uint32
}
func (e *Numgen) marshal(fam byte) ([]byte, error) {
// Currently only two types are supported, failing if Type is not of two known types
switch e.Type {
case unix.NFT_NG_INCREMENTAL:
case unix.NFT_NG_RANDOM:
default:
return nil, fmt.Errorf("unsupported numgen type %d", e.Type)
}
data, err := netlink.MarshalAttributes([]netlink.Attribute{
{Type: unix.NFTA_NG_DREG, Data: binaryutil.BigEndian.PutUint32(e.Register)},
{Type: unix.NFTA_NG_MODULUS, Data: binaryutil.BigEndian.PutUint32(e.Modulus)},
{Type: unix.NFTA_NG_TYPE, Data: binaryutil.BigEndian.PutUint32(e.Type)},
{Type: unix.NFTA_NG_OFFSET, Data: binaryutil.BigEndian.PutUint32(e.Offset)},
})
if err != nil {
return nil, err
}
return netlink.MarshalAttributes([]netlink.Attribute{
{Type: unix.NFTA_EXPR_NAME, Data: []byte("numgen\x00")},
{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: data},
})
}
func (e *Numgen) unmarshal(fam byte, data []byte) error {
ad, err := netlink.NewAttributeDecoder(data)
if err != nil {
return err
}
ad.ByteOrder = binary.BigEndian
for ad.Next() {
switch ad.Type() {
case unix.NFTA_NG_DREG:
e.Register = ad.Uint32()
case unix.NFTA_NG_MODULUS:
e.Modulus = ad.Uint32()
case unix.NFTA_NG_TYPE:
e.Type = ad.Uint32()
case unix.NFTA_NG_OFFSET:
e.Offset = ad.Uint32()
}
}
return ad.Err()
}
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