diff options
Diffstat (limited to 'vendor/github.com/google/gopacket/layers/gre.go')
| -rw-r--r-- | vendor/github.com/google/gopacket/layers/gre.go | 185 |
1 files changed, 185 insertions, 0 deletions
diff --git a/vendor/github.com/google/gopacket/layers/gre.go b/vendor/github.com/google/gopacket/layers/gre.go new file mode 100644 index 0000000..15d5290 --- /dev/null +++ b/vendor/github.com/google/gopacket/layers/gre.go @@ -0,0 +1,185 @@ +// 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" + + "github.com/google/gopacket" +) + +// GRE is a Generic Routing Encapsulation header. +type GRE struct { + BaseLayer + ChecksumPresent, RoutingPresent, KeyPresent, SeqPresent, StrictSourceRoute bool + RecursionControl, Flags, Version uint8 + Protocol EthernetType + Checksum, Offset uint16 + Key, Seq uint32 + *GRERouting +} + +// GRERouting is GRE routing information, present if the RoutingPresent flag is +// set. +type GRERouting struct { + AddressFamily uint16 + SREOffset, SRELength uint8 + RoutingInformation []byte + Next *GRERouting +} + +// LayerType returns gopacket.LayerTypeGRE. +func (g *GRE) LayerType() gopacket.LayerType { return LayerTypeGRE } + +// DecodeFromBytes decodes the given bytes into this layer. +func (g *GRE) DecodeFromBytes(data []byte, df gopacket.DecodeFeedback) error { + g.ChecksumPresent = data[0]&0x80 != 0 + g.RoutingPresent = data[0]&0x40 != 0 + g.KeyPresent = data[0]&0x20 != 0 + g.SeqPresent = data[0]&0x10 != 0 + g.StrictSourceRoute = data[0]&0x08 != 0 + g.RecursionControl = data[0] & 0x7 + g.Flags = data[1] >> 3 + g.Version = data[1] & 0x7 + g.Protocol = EthernetType(binary.BigEndian.Uint16(data[2:4])) + offset := 4 + if g.ChecksumPresent || g.RoutingPresent { + g.Checksum = binary.BigEndian.Uint16(data[offset : offset+2]) + g.Offset = binary.BigEndian.Uint16(data[offset+2 : offset+4]) + offset += 4 + } + if g.KeyPresent { + g.Key = binary.BigEndian.Uint32(data[offset : offset+4]) + offset += 4 + } + if g.SeqPresent { + g.Seq = binary.BigEndian.Uint32(data[offset : offset+4]) + offset += 4 + } + if g.RoutingPresent { + tail := &g.GRERouting + for { + sre := &GRERouting{ + AddressFamily: binary.BigEndian.Uint16(data[offset : offset+2]), + SREOffset: data[offset+2], + SRELength: data[offset+3], + } + sre.RoutingInformation = data[offset+4 : offset+4+int(sre.SRELength)] + offset += 4 + int(sre.SRELength) + if sre.AddressFamily == 0 && sre.SRELength == 0 { + break + } + (*tail) = sre + tail = &sre.Next + } + } + g.BaseLayer = BaseLayer{data[:offset], data[offset:]} + return nil +} + +// SerializeTo writes the serialized form of this layer into the SerializationBuffer, +// implementing gopacket.SerializableLayer. See the docs for gopacket.SerializableLayer for more info. +func (g *GRE) SerializeTo(b gopacket.SerializeBuffer, opts gopacket.SerializeOptions) error { + size := 4 + if g.ChecksumPresent || g.RoutingPresent { + size += 4 + } + if g.KeyPresent { + size += 4 + } + if g.SeqPresent { + size += 4 + } + if g.RoutingPresent { + r := g.GRERouting + for r != nil { + size += 4 + int(r.SRELength) + r = r.Next + } + size += 4 + } + buf, err := b.PrependBytes(size) + if err != nil { + return err + } + // Reset any potentially dirty memory in the first 2 bytes, as these use OR to set flags. + buf[0] = 0 + buf[1] = 0 + if g.ChecksumPresent { + buf[0] |= 0x80 + } + if g.RoutingPresent { + buf[0] |= 0x40 + } + if g.KeyPresent { + buf[0] |= 0x20 + } + if g.SeqPresent { + buf[0] |= 0x10 + } + if g.StrictSourceRoute { + buf[0] |= 0x08 + } + buf[0] |= g.RecursionControl + buf[1] |= g.Flags << 3 + buf[1] |= g.Version + binary.BigEndian.PutUint16(buf[2:4], uint16(g.Protocol)) + offset := 4 + if g.ChecksumPresent || g.RoutingPresent { + // Don't write the checksum value yet, as we may need to compute it, + // which requires the entire header be complete. + // Instead we zeroize the memory in case it is dirty. + buf[offset] = 0 + buf[offset+1] = 0 + binary.BigEndian.PutUint16(buf[offset+2:offset+4], g.Offset) + offset += 4 + } + if g.KeyPresent { + binary.BigEndian.PutUint32(buf[offset:offset+4], g.Key) + offset += 4 + } + if g.SeqPresent { + binary.BigEndian.PutUint32(buf[offset:offset+4], g.Seq) + offset += 4 + } + if g.RoutingPresent { + sre := g.GRERouting + for sre != nil { + binary.BigEndian.PutUint16(buf[offset:offset+2], sre.AddressFamily) + buf[offset+2] = sre.SREOffset + buf[offset+3] = sre.SRELength + copy(buf[offset+4:offset+4+int(sre.SRELength)], sre.RoutingInformation) + offset += 4 + int(sre.SRELength) + sre = sre.Next + } + // Terminate routing field with a "NULL" SRE. + binary.BigEndian.PutUint32(buf[offset:offset+4], 0) + } + if g.ChecksumPresent { + if opts.ComputeChecksums { + g.Checksum = tcpipChecksum(b.Bytes(), 0) + } + + binary.BigEndian.PutUint16(buf[4:6], g.Checksum) + } + return nil +} + +// CanDecode returns the set of layer types that this DecodingLayer can decode. +func (g *GRE) CanDecode() gopacket.LayerClass { + return LayerTypeGRE +} + +// NextLayerType returns the layer type contained by this DecodingLayer. +func (g *GRE) NextLayerType() gopacket.LayerType { + return g.Protocol.LayerType() +} + +func decodeGRE(data []byte, p gopacket.PacketBuilder) error { + g := &GRE{} + return decodingLayerDecoder(g, data, p) +} |