TUN-6666: Define packet package

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

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

@@ -0,0 +1,93 @@
+// 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"
+	"fmt"
+	"github.com/google/gopacket"
+)
+
+type RUDP struct {
+	BaseLayer
+	SYN, ACK, EACK, RST, NUL bool
+	Version                  uint8
+	HeaderLength             uint8
+	SrcPort, DstPort         RUDPPort
+	DataLength               uint16
+	Seq, Ack, Checksum       uint32
+	VariableHeaderArea       []byte
+	// RUDPHeaderSyn contains SYN information for the RUDP packet,
+	// if the SYN flag is set
+	*RUDPHeaderSYN
+	// RUDPHeaderEack contains EACK information for the RUDP packet,
+	// if the EACK flag is set.
+	*RUDPHeaderEACK
+}
+
+type RUDPHeaderSYN struct {
+	MaxOutstandingSegments, MaxSegmentSize, OptionFlags uint16
+}
+
+type RUDPHeaderEACK struct {
+	SeqsReceivedOK []uint32
+}
+
+// LayerType returns gopacket.LayerTypeRUDP.
+func (r *RUDP) LayerType() gopacket.LayerType { return LayerTypeRUDP }
+
+func decodeRUDP(data []byte, p gopacket.PacketBuilder) error {
+	r := &RUDP{
+		SYN:          data[0]&0x80 != 0,
+		ACK:          data[0]&0x40 != 0,
+		EACK:         data[0]&0x20 != 0,
+		RST:          data[0]&0x10 != 0,
+		NUL:          data[0]&0x08 != 0,
+		Version:      data[0] & 0x3,
+		HeaderLength: data[1],
+		SrcPort:      RUDPPort(data[2]),
+		DstPort:      RUDPPort(data[3]),
+		DataLength:   binary.BigEndian.Uint16(data[4:6]),
+		Seq:          binary.BigEndian.Uint32(data[6:10]),
+		Ack:          binary.BigEndian.Uint32(data[10:14]),
+		Checksum:     binary.BigEndian.Uint32(data[14:18]),
+	}
+	if r.HeaderLength < 9 {
+		return fmt.Errorf("RUDP packet with too-short header length %d", r.HeaderLength)
+	}
+	hlen := int(r.HeaderLength) * 2
+	r.Contents = data[:hlen]
+	r.Payload = data[hlen : hlen+int(r.DataLength)]
+	r.VariableHeaderArea = data[18:hlen]
+	headerData := r.VariableHeaderArea
+	switch {
+	case r.SYN:
+		if len(headerData) != 6 {
+			return fmt.Errorf("RUDP packet invalid SYN header length: %d", len(headerData))
+		}
+		r.RUDPHeaderSYN = &RUDPHeaderSYN{
+			MaxOutstandingSegments: binary.BigEndian.Uint16(headerData[:2]),
+			MaxSegmentSize:         binary.BigEndian.Uint16(headerData[2:4]),
+			OptionFlags:            binary.BigEndian.Uint16(headerData[4:6]),
+		}
+	case r.EACK:
+		if len(headerData)%4 != 0 {
+			return fmt.Errorf("RUDP packet invalid EACK header length: %d", len(headerData))
+		}
+		r.RUDPHeaderEACK = &RUDPHeaderEACK{make([]uint32, len(headerData)/4)}
+		for i := 0; i < len(headerData); i += 4 {
+			r.SeqsReceivedOK[i/4] = binary.BigEndian.Uint32(headerData[i : i+4])
+		}
+	}
+	p.AddLayer(r)
+	p.SetTransportLayer(r)
+	return p.NextDecoder(gopacket.LayerTypePayload)
+}
+
+func (r *RUDP) TransportFlow() gopacket.Flow {
+	return gopacket.NewFlow(EndpointRUDPPort, []byte{byte(r.SrcPort)}, []byte{byte(r.DstPort)})
+}