优化抓包性能

vendor/github.com/google/gopacket/layers/gen2.go

@@ -0,0 +1,104 @@
+// 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.
+
+// +build ignore
+
+// This binary handles creating string constants and function templates for enums.
+//
+//  go run gen.go | gofmt > enums_generated.go
+package main
+
+import (
+	"fmt"
+	"log"
+	"os"
+	"text/template"
+	"time"
+)
+
+const fmtString = `// Copyright 2012 Google, Inc. All rights reserved.
+
+package layers
+
+// Created by gen2.go, don't edit manually
+// Generated at %s
+
+import (
+  "fmt"
+
+  "github.com/google/gopacket"
+)
+
+`
+
+var funcsTmpl = template.Must(template.New("foo").Parse(`
+// Decoder calls {{.Name}}Metadata.DecodeWith's decoder.
+func (a {{.Name}}) Decode(data []byte, p gopacket.PacketBuilder) error {
+	return {{.Name}}Metadata[a].DecodeWith.Decode(data, p)
+}
+// String returns {{.Name}}Metadata.Name.
+func (a {{.Name}}) String() string {
+	return {{.Name}}Metadata[a].Name
+}
+// LayerType returns {{.Name}}Metadata.LayerType.
+func (a {{.Name}}) LayerType() gopacket.LayerType {
+	return {{.Name}}Metadata[a].LayerType
+}
+
+type errorDecoderFor{{.Name}} int
+func (a *errorDecoderFor{{.Name}}) Decode(data []byte, p gopacket.PacketBuilder) error {
+  return a
+}
+func (a *errorDecoderFor{{.Name}}) Error() string {
+  return fmt.Sprintf("Unable to decode {{.Name}} %d", int(*a))
+}
+
+var errorDecodersFor{{.Name}} [{{.Num}}]errorDecoderFor{{.Name}}
+var {{.Name}}Metadata [{{.Num}}]EnumMetadata
+
+func initUnknownTypesFor{{.Name}}() {
+  for i := 0; i < {{.Num}}; i++ {
+    errorDecodersFor{{.Name}}[i] = errorDecoderFor{{.Name}}(i)
+    {{.Name}}Metadata[i] = EnumMetadata{
+      DecodeWith: &errorDecodersFor{{.Name}}[i],
+      Name: "Unknown{{.Name}}",
+    }
+  }
+}
+`))
+
+func main() {
+	fmt.Fprintf(os.Stderr, "Writing results to stdout\n")
+	fmt.Printf(fmtString, time.Now())
+	types := []struct {
+		Name string
+		Num  int
+	}{
+		{"LinkType", 256},
+		{"EthernetType", 65536},
+		{"PPPType", 65536},
+		{"IPProtocol", 256},
+		{"SCTPChunkType", 256},
+		{"PPPoECode", 256},
+		{"FDDIFrameControl", 256},
+		{"EAPOLType", 256},
+		{"ProtocolFamily", 256},
+		{"Dot11Type", 256},
+		{"USBTransportType", 256},
+	}
+
+	fmt.Println("func init() {")
+	for _, t := range types {
+		fmt.Printf("initUnknownTypesFor%s()\n", t.Name)
+	}
+	fmt.Println("initActualTypeData()")
+	fmt.Println("}")
+	for _, t := range types {
+		if err := funcsTmpl.Execute(os.Stdout, t); err != nil {
+			log.Fatalf("Failed to execute template %s: %v", t.Name, err)
+		}
+	}
+}