87 lines
2.4 KiB
Go
87 lines
2.4 KiB
Go
// Copyright 2018 Google LLC. All Rights Reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package expr
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import (
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"encoding/binary"
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"github.com/google/nftables/binaryutil"
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"github.com/mdlayher/netlink"
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"golang.org/x/sys/unix"
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)
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const (
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// NFTA_TPROXY_FAMILY defines attribute for a table family
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NFTA_TPROXY_FAMILY = 0x01
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// NFTA_TPROXY_REG_ADDR defines attribute for a register carrying redirection address value
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NFTA_TPROXY_REG_ADDR = 0x02
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// NFTA_TPROXY_REG_PORT defines attribute for a register carrying redirection port value
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NFTA_TPROXY_REG_PORT = 0x03
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)
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// TProxy defines struct with parameters for the transparent proxy
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type TProxy struct {
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Family byte
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TableFamily byte
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RegAddr uint32
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RegPort uint32
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}
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func (e *TProxy) marshal(fam byte) ([]byte, error) {
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data, err := e.marshalData(fam)
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if err != nil {
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return nil, err
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}
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return netlink.MarshalAttributes([]netlink.Attribute{
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{Type: unix.NFTA_EXPR_NAME, Data: []byte("tproxy\x00")},
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{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: data},
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})
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}
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func (e *TProxy) marshalData(fam byte) ([]byte, error) {
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attrs := []netlink.Attribute{
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{Type: NFTA_TPROXY_FAMILY, Data: binaryutil.BigEndian.PutUint32(uint32(e.Family))},
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{Type: NFTA_TPROXY_REG_PORT, Data: binaryutil.BigEndian.PutUint32(e.RegPort)},
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}
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if e.RegAddr != 0 {
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attrs = append(attrs, netlink.Attribute{
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Type: NFTA_TPROXY_REG_ADDR,
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Data: binaryutil.BigEndian.PutUint32(e.RegAddr),
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})
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}
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return netlink.MarshalAttributes(attrs)
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}
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func (e *TProxy) unmarshal(fam byte, data []byte) error {
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ad, err := netlink.NewAttributeDecoder(data)
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if err != nil {
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return err
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}
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ad.ByteOrder = binary.BigEndian
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for ad.Next() {
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switch ad.Type() {
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case NFTA_TPROXY_FAMILY:
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e.Family = ad.Uint8()
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case NFTA_TPROXY_REG_PORT:
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e.RegPort = ad.Uint32()
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case NFTA_TPROXY_REG_ADDR:
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e.RegAddr = ad.Uint32()
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}
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}
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return ad.Err()
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}
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