95 lines
2.1 KiB
Go
95 lines
2.1 KiB
Go
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// 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 userdata implements a TLV parser/serializer for libnftables-compatible comments
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package userdata
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import (
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"bytes"
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"encoding/binary"
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)
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type Type byte
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// TLV type values are defined in:
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// https://git.netfilter.org/iptables/tree/iptables/nft.c?id=73611d5582e72367a698faf1b5301c836e981465#n1659
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const (
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TypeComment Type = iota
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TypeEbtablesPolicy
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TypesCount
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)
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func Append(udata []byte, typ Type, data []byte) []byte {
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udata = append(udata, byte(typ), byte(len(data)))
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udata = append(udata, data...)
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return udata
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}
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func Get(udata []byte, styp Type) []byte {
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for {
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if len(udata) < 2 {
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break
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}
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typ := Type(udata[0])
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length := int(udata[1])
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data := udata[2 : 2+length]
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if styp == typ {
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return data
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}
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if len(udata) < 2+length {
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break
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} else {
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udata = udata[2+length:]
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}
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}
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return nil
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}
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func AppendUint32(udata []byte, typ Type, num uint32) []byte {
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data := binary.LittleEndian.AppendUint32(nil, num)
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return Append(udata, typ, data)
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}
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func GetUint32(udata []byte, typ Type) (uint32, bool) {
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data := Get(udata, typ)
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if data == nil {
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return 0, false
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}
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return binary.LittleEndian.Uint32(data), true
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}
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func AppendString(udata []byte, typ Type, str string) []byte {
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data := append([]byte(str), 0)
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return Append(udata, typ, data)
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}
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func GetString(udata []byte, typ Type) (string, bool) {
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data := Get(udata, typ)
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if data == nil {
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return "", false
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}
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data, _ = bytes.CutSuffix(data, []byte{0})
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return string(data), true
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}
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