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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"
)
const (
// NFTA_TPROXY_FAMILY defines attribute for a table family
NFTA_TPROXY_FAMILY = 0x01
// NFTA_TPROXY_REG_ADDR defines attribute for a register carrying redirection address value
NFTA_TPROXY_REG_ADDR = 0x02
// NFTA_TPROXY_REG_PORT defines attribute for a register carrying redirection port value
NFTA_TPROXY_REG_PORT = 0x03
)
// TProxy defines struct with parameters for the transparent proxy
type TProxy struct {
Family byte
TableFamily byte
RegAddr uint32
RegPort uint32
}
func (e *TProxy) marshal(fam byte) ([]byte, error) {
attrs := []netlink.Attribute{
{Type: NFTA_TPROXY_FAMILY, Data: binaryutil.BigEndian.PutUint32(uint32(e.Family))},
{Type: NFTA_TPROXY_REG_PORT, Data: binaryutil.BigEndian.PutUint32(e.RegPort)},
}
if e.RegAddr != 0 {
attrs = append(attrs, netlink.Attribute{
Type: NFTA_TPROXY_REG_ADDR,
Data: binaryutil.BigEndian.PutUint32(e.RegAddr),
})
}
data, err := netlink.MarshalAttributes(attrs)
if err != nil {
return nil, err
}
return netlink.MarshalAttributes([]netlink.Attribute{
{Type: unix.NFTA_EXPR_NAME, Data: []byte("tproxy\x00")},
{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: data},
})
}
func (e *TProxy) 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 NFTA_TPROXY_FAMILY:
e.Family = ad.Uint8()
case NFTA_TPROXY_REG_PORT:
e.RegPort = ad.Uint32()
case NFTA_TPROXY_REG_ADDR:
e.RegAddr = ad.Uint32()
}
}
return ad.Err()
}
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