107 lines
3.1 KiB
Go
107 lines
3.1 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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type ExthdrOp uint32
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const (
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ExthdrOpIpv6 ExthdrOp = unix.NFT_EXTHDR_OP_IPV6
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ExthdrOpTcpopt ExthdrOp = unix.NFT_EXTHDR_OP_TCPOPT
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)
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type Exthdr struct {
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DestRegister uint32
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Type uint8
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Offset uint32
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Len uint32
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Flags uint32
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Op ExthdrOp
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SourceRegister uint32
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}
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func (e *Exthdr) 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("exthdr\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 *Exthdr) marshalData(fam byte) ([]byte, error) {
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var attr []netlink.Attribute
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// Operations are differentiated by the Op and whether the SourceRegister
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// or DestRegister is set. Mixing them results in EOPNOTSUPP.
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if e.SourceRegister != 0 {
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attr = []netlink.Attribute{
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{Type: unix.NFTA_EXTHDR_SREG, Data: binaryutil.BigEndian.PutUint32(e.SourceRegister)}}
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} else {
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attr = []netlink.Attribute{
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{Type: unix.NFTA_EXTHDR_DREG, Data: binaryutil.BigEndian.PutUint32(e.DestRegister)}}
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}
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attr = append(attr,
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netlink.Attribute{Type: unix.NFTA_EXTHDR_TYPE, Data: []byte{e.Type}},
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netlink.Attribute{Type: unix.NFTA_EXTHDR_OFFSET, Data: binaryutil.BigEndian.PutUint32(e.Offset)},
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netlink.Attribute{Type: unix.NFTA_EXTHDR_LEN, Data: binaryutil.BigEndian.PutUint32(e.Len)},
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netlink.Attribute{Type: unix.NFTA_EXTHDR_OP, Data: binaryutil.BigEndian.PutUint32(uint32(e.Op))})
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// Flags is only set if DREG is set
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if e.DestRegister != 0 {
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attr = append(attr,
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netlink.Attribute{Type: unix.NFTA_EXTHDR_FLAGS, Data: binaryutil.BigEndian.PutUint32(e.Flags)})
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}
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return netlink.MarshalAttributes(attr)
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}
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func (e *Exthdr) 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 unix.NFTA_EXTHDR_DREG:
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e.DestRegister = ad.Uint32()
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case unix.NFTA_EXTHDR_TYPE:
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e.Type = ad.Uint8()
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case unix.NFTA_EXTHDR_OFFSET:
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e.Offset = ad.Uint32()
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case unix.NFTA_EXTHDR_LEN:
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e.Len = ad.Uint32()
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case unix.NFTA_EXTHDR_FLAGS:
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e.Flags = ad.Uint32()
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case unix.NFTA_EXTHDR_OP:
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e.Op = ExthdrOp(ad.Uint32())
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case unix.NFTA_EXTHDR_SREG:
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e.SourceRegister = 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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