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108 lines
2.9 KiB
108 lines
2.9 KiB
// Copyright 2012 Google, Inc. All rights reserved.
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//
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// Use of this source code is governed by a BSD-style license
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// that can be found in the LICENSE file in the root of the source
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// tree.
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package gopacket
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// LayerClass is a set of LayerTypes, used for grabbing one of a number of
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// different types from a packet.
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type LayerClass interface {
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// Contains returns true if the given layer type should be considered part
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// of this layer class.
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Contains(LayerType) bool
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// LayerTypes returns the set of all layer types in this layer class.
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// Note that this may not be a fast operation on all LayerClass
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// implementations.
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LayerTypes() []LayerType
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}
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// Contains implements LayerClass.
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func (l LayerType) Contains(a LayerType) bool {
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return l == a
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}
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// LayerTypes implements LayerClass.
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func (l LayerType) LayerTypes() []LayerType {
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return []LayerType{l}
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}
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// LayerClassSlice implements a LayerClass with a slice.
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type LayerClassSlice []bool
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// Contains returns true if the given layer type should be considered part
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// of this layer class.
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func (s LayerClassSlice) Contains(t LayerType) bool {
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return int(t) < len(s) && s[t]
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}
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// LayerTypes returns all layer types in this LayerClassSlice.
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// Because of LayerClassSlice's implementation, this could be quite slow.
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func (s LayerClassSlice) LayerTypes() (all []LayerType) {
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for i := 0; i < len(s); i++ {
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if s[i] {
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all = append(all, LayerType(i))
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}
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}
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return
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}
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// NewLayerClassSlice creates a new LayerClassSlice by creating a slice of
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// size max(types) and setting slice[t] to true for each type t. Note, if
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// you implement your own LayerType and give it a high value, this WILL create
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// a very large slice.
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func NewLayerClassSlice(types []LayerType) LayerClassSlice {
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var max LayerType
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for _, typ := range types {
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if typ > max {
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max = typ
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}
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}
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t := make([]bool, int(max+1))
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for _, typ := range types {
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t[typ] = true
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}
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return t
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}
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// LayerClassMap implements a LayerClass with a map.
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type LayerClassMap map[LayerType]bool
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// Contains returns true if the given layer type should be considered part
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// of this layer class.
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func (m LayerClassMap) Contains(t LayerType) bool {
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return m[t]
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}
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// LayerTypes returns all layer types in this LayerClassMap.
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func (m LayerClassMap) LayerTypes() (all []LayerType) {
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for t := range m {
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all = append(all, t)
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}
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return
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}
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// NewLayerClassMap creates a LayerClassMap and sets map[t] to true for each
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// type in types.
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func NewLayerClassMap(types []LayerType) LayerClassMap {
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m := LayerClassMap{}
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for _, typ := range types {
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m[typ] = true
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}
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return m
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}
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// NewLayerClass creates a LayerClass, attempting to be smart about which type
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// it creates based on which types are passed in.
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func NewLayerClass(types []LayerType) LayerClass {
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for _, typ := range types {
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if typ > maxLayerType {
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// NewLayerClassSlice could create a very large object, so instead create
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// a map.
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return NewLayerClassMap(types)
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}
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}
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return NewLayerClassSlice(types)
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}
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