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/*
* 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()
}
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