WIP: middleware/dnstap (#711)

middleware/dnstap add

vendor/github.com/farsightsec/golang-framestream/Encoder.go

@@ -0,0 +1,99 @@
+/*
+ * 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 framestream
+
+import (
+	"bufio"
+	"encoding/binary"
+	"io"
+)
+
+type EncoderOptions struct {
+	ContentType   []byte
+	Bidirectional bool
+}
+
+type Encoder struct {
+	writer *bufio.Writer
+	reader *bufio.Reader
+	opt    EncoderOptions
+	buf    []byte
+}
+
+func NewEncoder(w io.Writer, opt *EncoderOptions) (enc *Encoder, err error) {
+	if opt == nil {
+		opt = &EncoderOptions{}
+	}
+	enc = &Encoder{
+		writer: bufio.NewWriter(w),
+		opt:    *opt,
+	}
+
+	if opt.Bidirectional {
+		r, ok := w.(io.Reader)
+		if !ok {
+			return nil, ErrType
+		}
+		enc.reader = bufio.NewReader(r)
+		ready := ControlReady
+		ready.SetContentType(opt.ContentType)
+		if err = ready.EncodeFlush(enc.writer); err != nil {
+			return
+		}
+
+		var accept ControlFrame
+		if err = accept.DecodeTypeEscape(enc.reader, CONTROL_ACCEPT); err != nil {
+			return
+		}
+
+		if !accept.MatchContentType(opt.ContentType) {
+			return nil, ErrContentTypeMismatch
+		}
+	}
+
+	// Write the start control frame.
+	start := ControlStart
+	start.SetContentType(opt.ContentType)
+	err = start.Encode(enc.writer)
+	if err != nil {
+		return
+	}
+
+	return
+}
+
+func (enc *Encoder) Close() (err error) {
+	err = ControlStop.EncodeFlush(enc.writer)
+	if err != nil || !enc.opt.Bidirectional {
+		return
+	}
+
+	var finish ControlFrame
+	return finish.DecodeTypeEscape(enc.reader, CONTROL_FINISH)
+}
+
+func (enc *Encoder) Write(frame []byte) (n int, err error) {
+	err = binary.Write(enc.writer, binary.BigEndian, uint32(len(frame)))
+	if err != nil {
+		return
+	}
+	return enc.writer.Write(frame)
+}
+
+func (enc *Encoder) Flush() error {
+	return enc.writer.Flush()
+}