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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"
"github.com/google/nftables/binaryutil"
"github.com/mdlayher/netlink"
"golang.org/x/sys/unix"
)
type Bitwise struct {
SourceRegister uint32
DestRegister uint32
Len uint32
Mask []byte
Xor []byte
}
func (e *Bitwise) marshal(fam byte) ([]byte, error) {
mask, err := netlink.MarshalAttributes([]netlink.Attribute{
{Type: unix.NFTA_DATA_VALUE, Data: e.Mask},
})
if err != nil {
return nil, err
}
xor, err := netlink.MarshalAttributes([]netlink.Attribute{
{Type: unix.NFTA_DATA_VALUE, Data: e.Xor},
})
if err != nil {
return nil, err
}
data, err := netlink.MarshalAttributes([]netlink.Attribute{
{Type: unix.NFTA_BITWISE_SREG, Data: binaryutil.BigEndian.PutUint32(e.SourceRegister)},
{Type: unix.NFTA_BITWISE_DREG, Data: binaryutil.BigEndian.PutUint32(e.DestRegister)},
{Type: unix.NFTA_BITWISE_LEN, Data: binaryutil.BigEndian.PutUint32(e.Len)},
{Type: unix.NLA_F_NESTED | unix.NFTA_BITWISE_MASK, Data: mask},
{Type: unix.NLA_F_NESTED | unix.NFTA_BITWISE_XOR, Data: xor},
})
if err != nil {
return nil, err
}
return netlink.MarshalAttributes([]netlink.Attribute{
{Type: unix.NFTA_EXPR_NAME, Data: []byte("bitwise\x00")},
{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: data},
})
}
func (e *Bitwise) 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_BITWISE_SREG:
e.SourceRegister = ad.Uint32()
case unix.NFTA_BITWISE_DREG:
e.DestRegister = ad.Uint32()
case unix.NFTA_BITWISE_LEN:
e.Len = ad.Uint32()
case unix.NFTA_BITWISE_MASK:
// Since NFTA_BITWISE_MASK is nested, it requires additional decoding
ad.Nested(func(nad *netlink.AttributeDecoder) error {
for nad.Next() {
switch nad.Type() {
case unix.NFTA_DATA_VALUE:
e.Mask = nad.Bytes()
}
}
return nil
})
case unix.NFTA_BITWISE_XOR:
// Since NFTA_BITWISE_XOR is nested, it requires additional decoding
ad.Nested(func(nad *netlink.AttributeDecoder) error {
for nad.Next() {
switch nad.Type() {
case unix.NFTA_DATA_VALUE:
e.Xor = nad.Bytes()
}
}
return nil
})
}
}
return ad.Err()
}
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