diff options
Diffstat (limited to 'vendor/github.com/google/gopacket/layers/mpls.go')
-rw-r--r-- | vendor/github.com/google/gopacket/layers/mpls.go | 87 |
1 files changed, 87 insertions, 0 deletions
diff --git a/vendor/github.com/google/gopacket/layers/mpls.go b/vendor/github.com/google/gopacket/layers/mpls.go new file mode 100644 index 0000000..83079a0 --- /dev/null +++ b/vendor/github.com/google/gopacket/layers/mpls.go @@ -0,0 +1,87 @@ +// 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 layers + +import ( + "encoding/binary" + "errors" + "github.com/google/gopacket" +) + +// MPLS is the MPLS packet header. +type MPLS struct { + BaseLayer + Label uint32 + TrafficClass uint8 + StackBottom bool + TTL uint8 +} + +// LayerType returns gopacket.LayerTypeMPLS. +func (m *MPLS) LayerType() gopacket.LayerType { return LayerTypeMPLS } + +// ProtocolGuessingDecoder attempts to guess the protocol of the bytes it's +// given, then decode the packet accordingly. Its algorithm for guessing is: +// If the packet starts with byte 0x45-0x4F: IPv4 +// If the packet starts with byte 0x60-0x6F: IPv6 +// Otherwise: Error +// See draft-hsmit-isis-aal5mux-00.txt for more detail on this approach. +type ProtocolGuessingDecoder struct{} + +func (ProtocolGuessingDecoder) Decode(data []byte, p gopacket.PacketBuilder) error { + switch data[0] { + // 0x40 | header_len, where header_len is at least 5. + case 0x45, 0x46, 0x47, 0x48, 0x49, 0x4a, 0x4b, 0x4c, 0x4d, 0x4e, 0x4f: + return decodeIPv4(data, p) + // IPv6 can start with any byte whose first 4 bits are 0x6. + case 0x60, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6e, 0x6f: + return decodeIPv6(data, p) + } + return errors.New("Unable to guess protocol of packet data") +} + +// MPLSPayloadDecoder is the decoder used to data encapsulated by each MPLS +// layer. MPLS contains no type information, so we have to explicitly decide +// which decoder to use. This is initially set to ProtocolGuessingDecoder, our +// simple attempt at guessing protocols based on the first few bytes of data +// available to us. However, if you know that in your environment MPLS always +// encapsulates a specific protocol, you may reset this. +var MPLSPayloadDecoder gopacket.Decoder = ProtocolGuessingDecoder{} + +func decodeMPLS(data []byte, p gopacket.PacketBuilder) error { + decoded := binary.BigEndian.Uint32(data[:4]) + mpls := &MPLS{ + Label: decoded >> 12, + TrafficClass: uint8(decoded>>9) & 0x7, + StackBottom: decoded&0x100 != 0, + TTL: uint8(decoded), + BaseLayer: BaseLayer{data[:4], data[4:]}, + } + p.AddLayer(mpls) + if mpls.StackBottom { + return p.NextDecoder(MPLSPayloadDecoder) + } + return p.NextDecoder(gopacket.DecodeFunc(decodeMPLS)) +} + +// SerializeTo writes the serialized form of this layer into the +// SerializationBuffer, implementing gopacket.SerializableLayer. +// See the docs for gopacket.SerializableLayer for more info. +func (m *MPLS) SerializeTo(b gopacket.SerializeBuffer, opts gopacket.SerializeOptions) error { + bytes, err := b.PrependBytes(4) + if err != nil { + return err + } + encoded := m.Label << 12 + encoded |= uint32(m.TrafficClass) << 9 + encoded |= uint32(m.TTL) + if m.StackBottom { + encoded |= 0x100 + } + binary.BigEndian.PutUint32(bytes, encoded) + return nil +} |