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// Copyright 2023 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"
"golang.org/x/sys/unix"
"github.com/google/nftables/binaryutil"
"github.com/mdlayher/netlink"
)
type Socket struct {
Key SocketKey
Level uint32
Register uint32
}
type SocketKey uint32
const (
// TODO, Once the constants below are available in golang.org/x/sys/unix, switch to use those.
NFTA_SOCKET_KEY = 1
NFTA_SOCKET_DREG = 2
NFTA_SOCKET_LEVEL = 3
NFT_SOCKET_TRANSPARENT = 0
NFT_SOCKET_MARK = 1
NFT_SOCKET_WILDCARD = 2
NFT_SOCKET_CGROUPV2 = 3
SocketKeyTransparent SocketKey = NFT_SOCKET_TRANSPARENT
SocketKeyMark SocketKey = NFT_SOCKET_MARK
SocketKeyWildcard SocketKey = NFT_SOCKET_WILDCARD
SocketKeyCgroupv2 SocketKey = NFT_SOCKET_CGROUPV2
)
func (e *Socket) marshal(fam byte) ([]byte, error) {
// NOTE: Socket.Level is only used when Socket.Key == SocketKeyCgroupv2. But `nft` always encoding it. Check link below:
// http://git.netfilter.org/nftables/tree/src/netlink_linearize.c?id=0583bac241ea18c9d7f61cb20ca04faa1e043b78#n319
exprData, err := netlink.MarshalAttributes(
[]netlink.Attribute{
{Type: NFTA_SOCKET_DREG, Data: binaryutil.BigEndian.PutUint32(e.Register)},
{Type: NFTA_SOCKET_KEY, Data: binaryutil.BigEndian.PutUint32(uint32(e.Key))},
{Type: NFTA_SOCKET_LEVEL, Data: binaryutil.BigEndian.PutUint32(uint32(e.Level))},
},
)
if err != nil {
return nil, err
}
return netlink.MarshalAttributes([]netlink.Attribute{
{Type: unix.NFTA_EXPR_NAME, Data: []byte("socket\x00")},
{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: exprData},
})
}
func (e *Socket) 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_SOCKET_DREG:
e.Register = ad.Uint32()
case NFTA_SOCKET_KEY:
e.Key = SocketKey(ad.Uint32())
case NFTA_SOCKET_LEVEL:
e.Level = ad.Uint32()
}
}
return ad.Err()
}
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