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Diffstat (limited to 'vendor/github.com/google/gopacket/layertype.go')
-rw-r--r-- | vendor/github.com/google/gopacket/layertype.go | 111 |
1 files changed, 111 insertions, 0 deletions
diff --git a/vendor/github.com/google/gopacket/layertype.go b/vendor/github.com/google/gopacket/layertype.go new file mode 100644 index 0000000..3abfee1 --- /dev/null +++ b/vendor/github.com/google/gopacket/layertype.go @@ -0,0 +1,111 @@ +// Copyright 2012 Google, Inc. All rights reserved. +// +// Use of this source code is governed by a BSD-style license +// that can be found in the LICENSE file in the root of the source +// tree. + +package gopacket + +import ( + "fmt" + "strconv" +) + +// LayerType is a unique identifier for each type of layer. This enumeration +// does not match with any externally available numbering scheme... it's solely +// usable/useful within this library as a means for requesting layer types +// (see Packet.Layer) and determining which types of layers have been decoded. +// +// New LayerTypes may be created by calling gopacket.RegisterLayerType. +type LayerType int64 + +// LayerTypeMetadata contains metadata associated with each LayerType. +type LayerTypeMetadata struct { + // Name is the string returned by each layer type's String method. + Name string + // Decoder is the decoder to use when the layer type is passed in as a + // Decoder. + Decoder Decoder +} + +type layerTypeMetadata struct { + inUse bool + LayerTypeMetadata +} + +// DecodersByLayerName maps layer names to decoders for those layers. +// This allows users to specify decoders by name to a program and have that +// program pick the correct decoder accordingly. +var DecodersByLayerName = map[string]Decoder{} + +const maxLayerType = 2000 + +var ltMeta [maxLayerType]layerTypeMetadata +var ltMetaMap = map[LayerType]layerTypeMetadata{} + +// RegisterLayerType creates a new layer type and registers it globally. +// The number passed in must be unique, or a runtime panic will occur. Numbers +// 0-999 are reserved for the gopacket library. Numbers 1000-1999 should be +// used for common application-specific types, and are very fast. Any other +// number (negative or >= 2000) may be used for uncommon application-specific +// types, and are somewhat slower (they require a map lookup over an array +// index). +func RegisterLayerType(num int, meta LayerTypeMetadata) LayerType { + if 0 <= num && num < maxLayerType { + if ltMeta[num].inUse { + panic("Layer type already exists") + } + } else { + if ltMetaMap[LayerType(num)].inUse { + panic("Layer type already exists") + } + } + return OverrideLayerType(num, meta) +} + +// OverrideLayerType acts like RegisterLayerType, except that if the layer type +// has already been registered, it overrides the metadata with the passed-in +// metadata intead of panicing. +func OverrideLayerType(num int, meta LayerTypeMetadata) LayerType { + if 0 <= num && num < maxLayerType { + ltMeta[num] = layerTypeMetadata{ + inUse: true, + LayerTypeMetadata: meta, + } + } else { + ltMetaMap[LayerType(num)] = layerTypeMetadata{ + inUse: true, + LayerTypeMetadata: meta, + } + } + DecodersByLayerName[meta.Name] = meta.Decoder + return LayerType(num) +} + +// Decode decodes the given data using the decoder registered with the layer +// type. +func (t LayerType) Decode(data []byte, c PacketBuilder) error { + var d Decoder + if 0 <= int(t) && int(t) < maxLayerType { + d = ltMeta[int(t)].Decoder + } else { + d = ltMetaMap[t].Decoder + } + if d != nil { + return d.Decode(data, c) + } + return fmt.Errorf("Layer type %v has no associated decoder", t) +} + +// String returns the string associated with this layer type. +func (t LayerType) String() (s string) { + if 0 <= int(t) && int(t) < maxLayerType { + s = ltMeta[int(t)].Name + } else { + s = ltMetaMap[t].Name + } + if s == "" { + s = strconv.Itoa(int(t)) + } + return +} |