adding vendor folder

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

@@ -0,0 +1,198 @@
+// 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"
+)
+
+// DecodingLayer is an interface for packet layers that can decode themselves.
+//
+// The important part of DecodingLayer is that they decode themselves in-place.
+// Calling DecodeFromBytes on a DecodingLayer totally resets the entire layer to
+// the new state defined by the data passed in.  A returned error leaves the
+// DecodingLayer in an unknown intermediate state, thus its fields should not be
+// trusted.
+//
+// Because the DecodingLayer is resetting its own fields, a call to
+// DecodeFromBytes should normally not require any memory allocation.
+type DecodingLayer interface {
+	// DecodeFromBytes resets the internal state of this layer to the state
+	// defined by the passed-in bytes.  Slices in the DecodingLayer may
+	// reference the passed-in data, so care should be taken to copy it
+	// first should later modification of data be required before the
+	// DecodingLayer is discarded.
+	DecodeFromBytes(data []byte, df DecodeFeedback) error
+	// CanDecode returns the set of LayerTypes this DecodingLayer can
+	// decode.  For Layers that are also DecodingLayers, this will most
+	// often be that Layer's LayerType().
+	CanDecode() LayerClass
+	// NextLayerType returns the LayerType which should be used to decode
+	// the LayerPayload.
+	NextLayerType() LayerType
+	// LayerPayload is the set of bytes remaining to decode after a call to
+	// DecodeFromBytes.
+	LayerPayload() []byte
+}
+
+// DecodingLayerParser parses a given set of layer types.  See DecodeLayers for
+// more information on how DecodingLayerParser should be used.
+type DecodingLayerParser struct {
+	// DecodingLayerParserOptions is the set of options available to the
+	// user to define the parser's behavior.
+	DecodingLayerParserOptions
+	first    LayerType
+	decoders map[LayerType]DecodingLayer
+	df       DecodeFeedback
+	// Truncated is set when a decode layer detects that the packet has been
+	// truncated.
+	Truncated bool
+}
+
+// AddDecodingLayer adds a decoding layer to the parser.  This adds support for
+// the decoding layer's CanDecode layers to the parser... should they be
+// encountered, they'll be parsed.
+func (l *DecodingLayerParser) AddDecodingLayer(d DecodingLayer) {
+	for _, typ := range d.CanDecode().LayerTypes() {
+		l.decoders[typ] = d
+	}
+}
+
+// SetTruncated is used by DecodingLayers to set the Truncated boolean in the
+// DecodingLayerParser.  Users should simply read Truncated after calling
+// DecodeLayers.
+func (l *DecodingLayerParser) SetTruncated() {
+	l.Truncated = true
+}
+
+// NewDecodingLayerParser creates a new DecodingLayerParser and adds in all
+// of the given DecodingLayers with AddDecodingLayer.
+//
+// Each call to DecodeLayers will attempt to decode the given bytes first by
+// treating them as a 'first'-type layer, then by using NextLayerType on
+// subsequently decoded layers to find the next relevant decoder.  Should a
+// deoder not be available for the layer type returned by NextLayerType,
+// decoding will stop.
+func NewDecodingLayerParser(first LayerType, decoders ...DecodingLayer) *DecodingLayerParser {
+	dlp := &DecodingLayerParser{
+		decoders: make(map[LayerType]DecodingLayer),
+		first:    first,
+	}
+	dlp.df = dlp // Cast this once to the interface
+	for _, d := range decoders {
+		dlp.AddDecodingLayer(d)
+	}
+	return dlp
+}
+
+// DecodeLayers decodes as many layers as possible from the given data.  It
+// initially treats the data as layer type 'typ', then uses NextLayerType on
+// each subsequent decoded layer until it gets to a layer type it doesn't know
+// how to parse.
+//
+// For each layer successfully decoded, DecodeLayers appends the layer type to
+// the decoded slice.  DecodeLayers truncates the 'decoded' slice initially, so
+// there's no need to empty it yourself.
+//
+// This decoding method is about an order of magnitude faster than packet
+// decoding, because it only decodes known layers that have already been
+// allocated.  This means it doesn't need to allocate each layer it returns...
+// instead it overwrites the layers that already exist.
+//
+// Example usage:
+//    func main() {
+//      var eth layers.Ethernet
+//      var ip4 layers.IPv4
+//      var ip6 layers.IPv6
+//      var tcp layers.TCP
+//      var udp layers.UDP
+//      var payload gopacket.Payload
+//      parser := gopacket.NewDecodingLayerParser(layers.LayerTypeEthernet, &eth, &ip4, &ip6, &tcp, &udp, &payload)
+//      var source gopacket.PacketDataSource = getMyDataSource()
+//      decodedLayers := make([]gopacket.LayerType, 0, 10)
+//      for {
+//        data, _, err := source.ReadPacketData()
+//        if err == nil {
+//          fmt.Println("Error reading packet data: ", err)
+//          continue
+//        }
+//        fmt.Println("Decoding packet")
+//        err = parser.DecodeLayers(data, &decodedLayers)
+//        for _, typ := range decodedLayers {
+//          fmt.Println("  Successfully decoded layer type", typ)
+//          switch typ {
+//            case layers.LayerTypeEthernet:
+//              fmt.Println("    Eth ", eth.SrcMAC, eth.DstMAC)
+//            case layers.LayerTypeIPv4:
+//              fmt.Println("    IP4 ", ip4.SrcIP, ip4.DstIP)
+//            case layers.LayerTypeIPv6:
+//              fmt.Println("    IP6 ", ip6.SrcIP, ip6.DstIP)
+//            case layers.LayerTypeTCP:
+//              fmt.Println("    TCP ", tcp.SrcPort, tcp.DstPort)
+//            case layers.LayerTypeUDP:
+//              fmt.Println("    UDP ", udp.SrcPort, udp.DstPort)
+//          }
+//        }
+//        if decodedLayers.Truncated {
+//          fmt.Println("  Packet has been truncated")
+//        }
+//        if err != nil {
+//          fmt.Println("  Error encountered:", err)
+//        }
+//      }
+//    }
+//
+// If DecodeLayers is unable to decode the next layer type, it will return the
+// error UnsupportedLayerType.
+func (l *DecodingLayerParser) DecodeLayers(data []byte, decoded *[]LayerType) (err error) {
+	l.Truncated = false
+	if !l.IgnorePanic {
+		defer panicToError(&err)
+	}
+	typ := l.first
+	*decoded = (*decoded)[:0] // Truncated decoded layers.
+	for len(data) > 0 {
+		decoder, ok := l.decoders[typ]
+		if !ok {
+			return UnsupportedLayerType(typ)
+		} else if err = decoder.DecodeFromBytes(data, l.df); err != nil {
+			return err
+		}
+		*decoded = append(*decoded, typ)
+		typ = decoder.NextLayerType()
+		data = decoder.LayerPayload()
+	}
+	return nil
+}
+
+// UnsupportedLayerType is returned by DecodingLayerParser if DecodeLayers
+// encounters a layer type that the DecodingLayerParser has no decoder for.
+type UnsupportedLayerType LayerType
+
+// Error implements the error interface, returning a string to say that the
+// given layer type is unsupported.
+func (e UnsupportedLayerType) Error() string {
+	return fmt.Sprintf("No decoder for layer type %v", LayerType(e))
+}
+
+func panicToError(e *error) {
+	if r := recover(); r != nil {
+		*e = fmt.Errorf("panic: %v", r)
+	}
+}
+
+// DecodingLayerParserOptions provides options to affect the behavior of a given
+// DecodingLayerParser.
+type DecodingLayerParserOptions struct {
+	// IgnorePanic determines whether a DecodingLayerParser should stop
+	// panics on its own (by returning them as an error from DecodeLayers)
+	// or should allow them to raise up the stack.  Handling errors does add
+	// latency to the process of decoding layers, but is much safer for
+	// callers.  IgnorePanic defaults to false, thus if the caller does
+	// nothing decode panics will be returned as errors.
+	IgnorePanic bool
+}