TUN-6666: Define packet package

This package defines IP and ICMP packet, decoders, encoder and flow

vendor/github.com/google/gopacket/layers/dot1q.go

@@ -0,0 +1,75 @@
+// Copyright 2012 Google, Inc. All rights reserved.
+// Copyright 2009-2011 Andreas Krennmair. 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"
+	"fmt"
+	"github.com/google/gopacket"
+)
+
+// Dot1Q is the packet layer for 802.1Q VLAN headers.
+type Dot1Q struct {
+	BaseLayer
+	Priority       uint8
+	DropEligible   bool
+	VLANIdentifier uint16
+	Type           EthernetType
+}
+
+// LayerType returns gopacket.LayerTypeDot1Q
+func (d *Dot1Q) LayerType() gopacket.LayerType { return LayerTypeDot1Q }
+
+// DecodeFromBytes decodes the given bytes into this layer.
+func (d *Dot1Q) DecodeFromBytes(data []byte, df gopacket.DecodeFeedback) error {
+	if len(data) < 4 {
+		df.SetTruncated()
+		return fmt.Errorf("802.1Q tag length %d too short", len(data))
+	}
+	d.Priority = (data[0] & 0xE0) >> 5
+	d.DropEligible = data[0]&0x10 != 0
+	d.VLANIdentifier = binary.BigEndian.Uint16(data[:2]) & 0x0FFF
+	d.Type = EthernetType(binary.BigEndian.Uint16(data[2:4]))
+	d.BaseLayer = BaseLayer{Contents: data[:4], Payload: data[4:]}
+	return nil
+}
+
+// CanDecode returns the set of layer types that this DecodingLayer can decode.
+func (d *Dot1Q) CanDecode() gopacket.LayerClass {
+	return LayerTypeDot1Q
+}
+
+// NextLayerType returns the layer type contained by this DecodingLayer.
+func (d *Dot1Q) NextLayerType() gopacket.LayerType {
+	return d.Type.LayerType()
+}
+
+func decodeDot1Q(data []byte, p gopacket.PacketBuilder) error {
+	d := &Dot1Q{}
+	return decodingLayerDecoder(d, data, p)
+}
+
+// SerializeTo writes the serialized form of this layer into the
+// SerializationBuffer, implementing gopacket.SerializableLayer.
+// See the docs for gopacket.SerializableLayer for more info.
+func (d *Dot1Q) SerializeTo(b gopacket.SerializeBuffer, opts gopacket.SerializeOptions) error {
+	bytes, err := b.PrependBytes(4)
+	if err != nil {
+		return err
+	}
+	if d.VLANIdentifier > 0xFFF {
+		return fmt.Errorf("vlan identifier %v is too high", d.VLANIdentifier)
+	}
+	firstBytes := uint16(d.Priority)<<13 | d.VLANIdentifier
+	if d.DropEligible {
+		firstBytes |= 0x1000
+	}
+	binary.BigEndian.PutUint16(bytes, firstBytes)
+	binary.BigEndian.PutUint16(bytes[2:], uint16(d.Type))
+	return nil
+}