TUN-6666: Define packet package

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

vendor/github.com/google/gopacket/base.go

@@ -0,0 +1,178 @@
+// 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"
+)
+
+// Layer represents a single decoded packet layer (using either the
+// OSI or TCP/IP definition of a layer).  When decoding, a packet's data is
+// broken up into a number of layers.  The caller may call LayerType() to
+// figure out which type of layer they've received from the packet.  Optionally,
+// they may then use a type assertion to get the actual layer type for deep
+// inspection of the data.
+type Layer interface {
+	// LayerType is the gopacket type for this layer.
+	LayerType() LayerType
+	// LayerContents returns the set of bytes that make up this layer.
+	LayerContents() []byte
+	// LayerPayload returns the set of bytes contained within this layer, not
+	// including the layer itself.
+	LayerPayload() []byte
+}
+
+// Payload is a Layer containing the payload of a packet.  The definition of
+// what constitutes the payload of a packet depends on previous layers; for
+// TCP and UDP, we stop decoding above layer 4 and return the remaining
+// bytes as a Payload.  Payload is an ApplicationLayer.
+type Payload []byte
+
+// LayerType returns LayerTypePayload
+func (p Payload) LayerType() LayerType { return LayerTypePayload }
+
+// LayerContents returns the bytes making up this layer.
+func (p Payload) LayerContents() []byte { return []byte(p) }
+
+// LayerPayload returns the payload within this layer.
+func (p Payload) LayerPayload() []byte { return nil }
+
+// Payload returns this layer as bytes.
+func (p Payload) Payload() []byte { return []byte(p) }
+
+// String implements fmt.Stringer.
+func (p Payload) String() string { return fmt.Sprintf("%d byte(s)", len(p)) }
+
+// GoString implements fmt.GoStringer.
+func (p Payload) GoString() string { return LongBytesGoString([]byte(p)) }
+
+// CanDecode implements DecodingLayer.
+func (p Payload) CanDecode() LayerClass { return LayerTypePayload }
+
+// NextLayerType implements DecodingLayer.
+func (p Payload) NextLayerType() LayerType { return LayerTypeZero }
+
+// DecodeFromBytes implements DecodingLayer.
+func (p *Payload) DecodeFromBytes(data []byte, df DecodeFeedback) error {
+	*p = Payload(data)
+	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 (p Payload) SerializeTo(b SerializeBuffer, opts SerializeOptions) error {
+	bytes, err := b.PrependBytes(len(p))
+	if err != nil {
+		return err
+	}
+	copy(bytes, p)
+	return nil
+}
+
+// decodePayload decodes data by returning it all in a Payload layer.
+func decodePayload(data []byte, p PacketBuilder) error {
+	payload := &Payload{}
+	if err := payload.DecodeFromBytes(data, p); err != nil {
+		return err
+	}
+	p.AddLayer(payload)
+	p.SetApplicationLayer(payload)
+	return nil
+}
+
+// Fragment is a Layer containing a fragment of a larger frame, used by layers
+// like IPv4 and IPv6 that allow for fragmentation of their payloads.
+type Fragment []byte
+
+// LayerType returns LayerTypeFragment
+func (p *Fragment) LayerType() LayerType { return LayerTypeFragment }
+
+// LayerContents implements Layer.
+func (p *Fragment) LayerContents() []byte { return []byte(*p) }
+
+// LayerPayload implements Layer.
+func (p *Fragment) LayerPayload() []byte { return nil }
+
+// Payload returns this layer as a byte slice.
+func (p *Fragment) Payload() []byte { return []byte(*p) }
+
+// String implements fmt.Stringer.
+func (p *Fragment) String() string { return fmt.Sprintf("%d byte(s)", len(*p)) }
+
+// CanDecode implements DecodingLayer.
+func (p *Fragment) CanDecode() LayerClass { return LayerTypeFragment }
+
+// NextLayerType implements DecodingLayer.
+func (p *Fragment) NextLayerType() LayerType { return LayerTypeZero }
+
+// DecodeFromBytes implements DecodingLayer.
+func (p *Fragment) DecodeFromBytes(data []byte, df DecodeFeedback) error {
+	*p = Fragment(data)
+	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 (p *Fragment) SerializeTo(b SerializeBuffer, opts SerializeOptions) error {
+	bytes, err := b.PrependBytes(len(*p))
+	if err != nil {
+		return err
+	}
+	copy(bytes, *p)
+	return nil
+}
+
+// decodeFragment decodes data by returning it all in a Fragment layer.
+func decodeFragment(data []byte, p PacketBuilder) error {
+	payload := &Fragment{}
+	if err := payload.DecodeFromBytes(data, p); err != nil {
+		return err
+	}
+	p.AddLayer(payload)
+	p.SetApplicationLayer(payload)
+	return nil
+}
+
+// These layers correspond to Internet Protocol Suite (TCP/IP) layers, and their
+// corresponding OSI layers, as best as possible.
+
+// LinkLayer is the packet layer corresponding to TCP/IP layer 1 (OSI layer 2)
+type LinkLayer interface {
+	Layer
+	LinkFlow() Flow
+}
+
+// NetworkLayer is the packet layer corresponding to TCP/IP layer 2 (OSI
+// layer 3)
+type NetworkLayer interface {
+	Layer
+	NetworkFlow() Flow
+}
+
+// TransportLayer is the packet layer corresponding to the TCP/IP layer 3 (OSI
+// layer 4)
+type TransportLayer interface {
+	Layer
+	TransportFlow() Flow
+}
+
+// ApplicationLayer is the packet layer corresponding to the TCP/IP layer 4 (OSI
+// layer 7), also known as the packet payload.
+type ApplicationLayer interface {
+	Layer
+	Payload() []byte
+}
+
+// ErrorLayer is a packet layer created when decoding of the packet has failed.
+// Its payload is all the bytes that we were unable to decode, and the returned
+// error details why the decoding failed.
+type ErrorLayer interface {
+	Layer
+	Error() error
+}