WIP: middleware/dnstap (#711)

middleware/dnstap add

vendor/github.com/dnstap/golang-dnstap/TextOutput.go

@@ -0,0 +1,86 @@
+/*
+ * Copyright (c) 2014 by Farsight Security, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package dnstap
+
+import (
+	"bufio"
+	"io"
+	"log"
+	"os"
+
+	"github.com/golang/protobuf/proto"
+)
+
+type TextFormatFunc func(*Dnstap) ([]byte, bool)
+
+type TextOutput struct {
+	format        TextFormatFunc
+	outputChannel chan []byte
+	wait          chan bool
+	writer        *bufio.Writer
+}
+
+func NewTextOutput(writer io.Writer, format TextFormatFunc) (o *TextOutput) {
+	o = new(TextOutput)
+	o.format = format
+	o.outputChannel = make(chan []byte, outputChannelSize)
+	o.writer = bufio.NewWriter(writer)
+	o.wait = make(chan bool)
+	return
+}
+
+func NewTextOutputFromFilename(fname string, format TextFormatFunc) (o *TextOutput, err error) {
+	if fname == "" || fname == "-" {
+		return NewTextOutput(os.Stdout, format), nil
+	}
+	writer, err := os.Create(fname)
+	if err != nil {
+		return
+	}
+	return NewTextOutput(writer, format), nil
+}
+
+func (o *TextOutput) GetOutputChannel() chan []byte {
+	return o.outputChannel
+}
+
+func (o *TextOutput) RunOutputLoop() {
+	dt := &Dnstap{}
+	for frame := range o.outputChannel {
+		if err := proto.Unmarshal(frame, dt); err != nil {
+			log.Fatalf("dnstap.TextOutput: proto.Unmarshal() failed: %s\n", err)
+			break
+		}
+		buf, ok := o.format(dt)
+		if !ok {
+			log.Fatalf("dnstap.TextOutput: text format function failed\n")
+			break
+		}
+		if _, err := o.writer.Write(buf); err != nil {
+			log.Fatalf("dnstap.TextOutput: write failed: %s\n", err)
+			break
+		}
+		o.writer.Flush()
+	}
+	close(o.wait)
+}
+
+func (o *TextOutput) Close() {
+	close(o.outputChannel)
+	<-o.wait
+	o.writer.Flush()
+}