584 lines
16 KiB
Go
584 lines
16 KiB
Go
// Copyright 2011 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package websocket
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// This file implements a protocol of hybi draft.
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// http://tools.ietf.org/html/draft-ietf-hybi-thewebsocketprotocol-17
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import (
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"bufio"
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"bytes"
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"crypto/rand"
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"crypto/sha1"
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"encoding/base64"
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"encoding/binary"
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"fmt"
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"io"
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"io/ioutil"
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"net/http"
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"net/url"
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"strings"
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)
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const (
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websocketGUID = "258EAFA5-E914-47DA-95CA-C5AB0DC85B11"
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closeStatusNormal = 1000
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closeStatusGoingAway = 1001
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closeStatusProtocolError = 1002
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closeStatusUnsupportedData = 1003
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closeStatusFrameTooLarge = 1004
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closeStatusNoStatusRcvd = 1005
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closeStatusAbnormalClosure = 1006
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closeStatusBadMessageData = 1007
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closeStatusPolicyViolation = 1008
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closeStatusTooBigData = 1009
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closeStatusExtensionMismatch = 1010
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maxControlFramePayloadLength = 125
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)
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var (
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ErrBadMaskingKey = &ProtocolError{"bad masking key"}
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ErrBadPongMessage = &ProtocolError{"bad pong message"}
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ErrBadClosingStatus = &ProtocolError{"bad closing status"}
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ErrUnsupportedExtensions = &ProtocolError{"unsupported extensions"}
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ErrNotImplemented = &ProtocolError{"not implemented"}
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handshakeHeader = map[string]bool{
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"Host": true,
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"Upgrade": true,
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"Connection": true,
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"Sec-Websocket-Key": true,
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"Sec-Websocket-Origin": true,
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"Sec-Websocket-Version": true,
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"Sec-Websocket-Protocol": true,
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"Sec-Websocket-Accept": true,
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}
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)
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// A hybiFrameHeader is a frame header as defined in hybi draft.
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type hybiFrameHeader struct {
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Fin bool
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Rsv [3]bool
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OpCode byte
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Length int64
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MaskingKey []byte
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data *bytes.Buffer
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}
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// A hybiFrameReader is a reader for hybi frame.
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type hybiFrameReader struct {
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reader io.Reader
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header hybiFrameHeader
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pos int64
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length int
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}
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func (frame *hybiFrameReader) Read(msg []byte) (n int, err error) {
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n, err = frame.reader.Read(msg)
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if frame.header.MaskingKey != nil {
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for i := 0; i < n; i++ {
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msg[i] = msg[i] ^ frame.header.MaskingKey[frame.pos%4]
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frame.pos++
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}
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}
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return n, err
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}
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func (frame *hybiFrameReader) PayloadType() byte { return frame.header.OpCode }
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func (frame *hybiFrameReader) HeaderReader() io.Reader {
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if frame.header.data == nil {
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return nil
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}
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if frame.header.data.Len() == 0 {
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return nil
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}
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return frame.header.data
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}
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func (frame *hybiFrameReader) TrailerReader() io.Reader { return nil }
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func (frame *hybiFrameReader) Len() (n int) { return frame.length }
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// A hybiFrameReaderFactory creates new frame reader based on its frame type.
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type hybiFrameReaderFactory struct {
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*bufio.Reader
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}
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// NewFrameReader reads a frame header from the connection, and creates new reader for the frame.
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// See Section 5.2 Base Framing protocol for detail.
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// http://tools.ietf.org/html/draft-ietf-hybi-thewebsocketprotocol-17#section-5.2
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func (buf hybiFrameReaderFactory) NewFrameReader() (frame frameReader, err error) {
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hybiFrame := new(hybiFrameReader)
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frame = hybiFrame
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var header []byte
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var b byte
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// First byte. FIN/RSV1/RSV2/RSV3/OpCode(4bits)
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b, err = buf.ReadByte()
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if err != nil {
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return
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}
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header = append(header, b)
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hybiFrame.header.Fin = ((header[0] >> 7) & 1) != 0
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for i := 0; i < 3; i++ {
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j := uint(6 - i)
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hybiFrame.header.Rsv[i] = ((header[0] >> j) & 1) != 0
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}
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hybiFrame.header.OpCode = header[0] & 0x0f
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// Second byte. Mask/Payload len(7bits)
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b, err = buf.ReadByte()
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if err != nil {
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return
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}
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header = append(header, b)
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mask := (b & 0x80) != 0
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b &= 0x7f
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lengthFields := 0
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switch {
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case b <= 125: // Payload length 7bits.
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hybiFrame.header.Length = int64(b)
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case b == 126: // Payload length 7+16bits
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lengthFields = 2
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case b == 127: // Payload length 7+64bits
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lengthFields = 8
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}
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for i := 0; i < lengthFields; i++ {
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b, err = buf.ReadByte()
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if err != nil {
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return
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}
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if lengthFields == 8 && i == 0 { // MSB must be zero when 7+64 bits
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b &= 0x7f
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}
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header = append(header, b)
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hybiFrame.header.Length = hybiFrame.header.Length*256 + int64(b)
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}
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if mask {
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// Masking key. 4 bytes.
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for i := 0; i < 4; i++ {
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b, err = buf.ReadByte()
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if err != nil {
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return
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}
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header = append(header, b)
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hybiFrame.header.MaskingKey = append(hybiFrame.header.MaskingKey, b)
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}
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}
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hybiFrame.reader = io.LimitReader(buf.Reader, hybiFrame.header.Length)
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hybiFrame.header.data = bytes.NewBuffer(header)
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hybiFrame.length = len(header) + int(hybiFrame.header.Length)
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return
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}
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// A HybiFrameWriter is a writer for hybi frame.
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type hybiFrameWriter struct {
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writer *bufio.Writer
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header *hybiFrameHeader
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}
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func (frame *hybiFrameWriter) Write(msg []byte) (n int, err error) {
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var header []byte
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var b byte
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if frame.header.Fin {
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b |= 0x80
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}
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for i := 0; i < 3; i++ {
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if frame.header.Rsv[i] {
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j := uint(6 - i)
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b |= 1 << j
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}
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}
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b |= frame.header.OpCode
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header = append(header, b)
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if frame.header.MaskingKey != nil {
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b = 0x80
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} else {
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b = 0
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}
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lengthFields := 0
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length := len(msg)
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switch {
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case length <= 125:
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b |= byte(length)
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case length < 65536:
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b |= 126
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lengthFields = 2
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default:
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b |= 127
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lengthFields = 8
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}
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header = append(header, b)
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for i := 0; i < lengthFields; i++ {
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j := uint((lengthFields - i - 1) * 8)
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b = byte((length >> j) & 0xff)
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header = append(header, b)
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}
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if frame.header.MaskingKey != nil {
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if len(frame.header.MaskingKey) != 4 {
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return 0, ErrBadMaskingKey
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}
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header = append(header, frame.header.MaskingKey...)
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frame.writer.Write(header)
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data := make([]byte, length)
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for i := range data {
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data[i] = msg[i] ^ frame.header.MaskingKey[i%4]
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}
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frame.writer.Write(data)
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err = frame.writer.Flush()
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return length, err
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}
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frame.writer.Write(header)
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frame.writer.Write(msg)
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err = frame.writer.Flush()
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return length, err
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}
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func (frame *hybiFrameWriter) Close() error { return nil }
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type hybiFrameWriterFactory struct {
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*bufio.Writer
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needMaskingKey bool
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}
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func (buf hybiFrameWriterFactory) NewFrameWriter(payloadType byte) (frame frameWriter, err error) {
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frameHeader := &hybiFrameHeader{Fin: true, OpCode: payloadType}
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if buf.needMaskingKey {
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frameHeader.MaskingKey, err = generateMaskingKey()
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if err != nil {
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return nil, err
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}
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}
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return &hybiFrameWriter{writer: buf.Writer, header: frameHeader}, nil
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}
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type hybiFrameHandler struct {
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conn *Conn
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payloadType byte
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}
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func (handler *hybiFrameHandler) HandleFrame(frame frameReader) (frameReader, error) {
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if handler.conn.IsServerConn() {
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// The client MUST mask all frames sent to the server.
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if frame.(*hybiFrameReader).header.MaskingKey == nil {
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handler.WriteClose(closeStatusProtocolError)
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return nil, io.EOF
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}
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} else {
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// The server MUST NOT mask all frames.
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if frame.(*hybiFrameReader).header.MaskingKey != nil {
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handler.WriteClose(closeStatusProtocolError)
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return nil, io.EOF
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}
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}
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if header := frame.HeaderReader(); header != nil {
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io.Copy(ioutil.Discard, header)
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}
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switch frame.PayloadType() {
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case ContinuationFrame:
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frame.(*hybiFrameReader).header.OpCode = handler.payloadType
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case TextFrame, BinaryFrame:
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handler.payloadType = frame.PayloadType()
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case CloseFrame:
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return nil, io.EOF
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case PingFrame, PongFrame:
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b := make([]byte, maxControlFramePayloadLength)
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n, err := io.ReadFull(frame, b)
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if err != nil && err != io.EOF && err != io.ErrUnexpectedEOF {
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return nil, err
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}
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io.Copy(ioutil.Discard, frame)
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if frame.PayloadType() == PingFrame {
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if _, err := handler.WritePong(b[:n]); err != nil {
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return nil, err
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}
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}
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return nil, nil
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}
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return frame, nil
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}
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func (handler *hybiFrameHandler) WriteClose(status int) (err error) {
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handler.conn.wio.Lock()
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defer handler.conn.wio.Unlock()
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w, err := handler.conn.frameWriterFactory.NewFrameWriter(CloseFrame)
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if err != nil {
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return err
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}
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msg := make([]byte, 2)
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binary.BigEndian.PutUint16(msg, uint16(status))
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_, err = w.Write(msg)
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w.Close()
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return err
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}
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func (handler *hybiFrameHandler) WritePong(msg []byte) (n int, err error) {
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handler.conn.wio.Lock()
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defer handler.conn.wio.Unlock()
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w, err := handler.conn.frameWriterFactory.NewFrameWriter(PongFrame)
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if err != nil {
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return 0, err
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}
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n, err = w.Write(msg)
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w.Close()
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return n, err
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}
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// newHybiConn creates a new WebSocket connection speaking hybi draft protocol.
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func newHybiConn(config *Config, buf *bufio.ReadWriter, rwc io.ReadWriteCloser, request *http.Request) *Conn {
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if buf == nil {
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br := bufio.NewReader(rwc)
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bw := bufio.NewWriter(rwc)
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buf = bufio.NewReadWriter(br, bw)
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}
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ws := &Conn{config: config, request: request, buf: buf, rwc: rwc,
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frameReaderFactory: hybiFrameReaderFactory{buf.Reader},
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frameWriterFactory: hybiFrameWriterFactory{
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buf.Writer, request == nil},
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PayloadType: TextFrame,
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defaultCloseStatus: closeStatusNormal}
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ws.frameHandler = &hybiFrameHandler{conn: ws}
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return ws
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}
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// generateMaskingKey generates a masking key for a frame.
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func generateMaskingKey() (maskingKey []byte, err error) {
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maskingKey = make([]byte, 4)
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if _, err = io.ReadFull(rand.Reader, maskingKey); err != nil {
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return
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}
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return
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}
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// generateNonce generates a nonce consisting of a randomly selected 16-byte
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// value that has been base64-encoded.
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func generateNonce() (nonce []byte) {
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key := make([]byte, 16)
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if _, err := io.ReadFull(rand.Reader, key); err != nil {
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panic(err)
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}
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nonce = make([]byte, 24)
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base64.StdEncoding.Encode(nonce, key)
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return
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}
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// removeZone removes IPv6 zone identifier from host.
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// E.g., "[fe80::1%en0]:8080" to "[fe80::1]:8080"
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func removeZone(host string) string {
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if !strings.HasPrefix(host, "[") {
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return host
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}
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i := strings.LastIndex(host, "]")
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if i < 0 {
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return host
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}
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j := strings.LastIndex(host[:i], "%")
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if j < 0 {
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return host
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}
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return host[:j] + host[i:]
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}
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// getNonceAccept computes the base64-encoded SHA-1 of the concatenation of
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// the nonce ("Sec-WebSocket-Key" value) with the websocket GUID string.
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func getNonceAccept(nonce []byte) (expected []byte, err error) {
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h := sha1.New()
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if _, err = h.Write(nonce); err != nil {
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return
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}
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if _, err = h.Write([]byte(websocketGUID)); err != nil {
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return
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}
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expected = make([]byte, 28)
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base64.StdEncoding.Encode(expected, h.Sum(nil))
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return
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}
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// Client handshake described in draft-ietf-hybi-thewebsocket-protocol-17
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func hybiClientHandshake(config *Config, br *bufio.Reader, bw *bufio.Writer) (err error) {
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bw.WriteString("GET " + config.Location.RequestURI() + " HTTP/1.1\r\n")
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// According to RFC 6874, an HTTP client, proxy, or other
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// intermediary must remove any IPv6 zone identifier attached
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// to an outgoing URI.
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bw.WriteString("Host: " + removeZone(config.Location.Host) + "\r\n")
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bw.WriteString("Upgrade: websocket\r\n")
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bw.WriteString("Connection: Upgrade\r\n")
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nonce := generateNonce()
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if config.handshakeData != nil {
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nonce = []byte(config.handshakeData["key"])
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}
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bw.WriteString("Sec-WebSocket-Key: " + string(nonce) + "\r\n")
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bw.WriteString("Origin: " + strings.ToLower(config.Origin.String()) + "\r\n")
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if config.Version != ProtocolVersionHybi13 {
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return ErrBadProtocolVersion
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}
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bw.WriteString("Sec-WebSocket-Version: " + fmt.Sprintf("%d", config.Version) + "\r\n")
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if len(config.Protocol) > 0 {
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bw.WriteString("Sec-WebSocket-Protocol: " + strings.Join(config.Protocol, ", ") + "\r\n")
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}
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// TODO(ukai): send Sec-WebSocket-Extensions.
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err = config.Header.WriteSubset(bw, handshakeHeader)
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if err != nil {
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return err
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}
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bw.WriteString("\r\n")
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if err = bw.Flush(); err != nil {
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return err
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}
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resp, err := http.ReadResponse(br, &http.Request{Method: "GET"})
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if err != nil {
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return err
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}
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if resp.StatusCode != 101 {
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return ErrBadStatus
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}
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if strings.ToLower(resp.Header.Get("Upgrade")) != "websocket" ||
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strings.ToLower(resp.Header.Get("Connection")) != "upgrade" {
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return ErrBadUpgrade
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}
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expectedAccept, err := getNonceAccept(nonce)
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if err != nil {
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return err
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}
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if resp.Header.Get("Sec-WebSocket-Accept") != string(expectedAccept) {
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return ErrChallengeResponse
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}
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if resp.Header.Get("Sec-WebSocket-Extensions") != "" {
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return ErrUnsupportedExtensions
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}
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offeredProtocol := resp.Header.Get("Sec-WebSocket-Protocol")
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if offeredProtocol != "" {
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protocolMatched := false
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for i := 0; i < len(config.Protocol); i++ {
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if config.Protocol[i] == offeredProtocol {
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protocolMatched = true
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break
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}
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}
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if !protocolMatched {
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return ErrBadWebSocketProtocol
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}
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config.Protocol = []string{offeredProtocol}
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}
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return nil
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}
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// newHybiClientConn creates a client WebSocket connection after handshake.
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func newHybiClientConn(config *Config, buf *bufio.ReadWriter, rwc io.ReadWriteCloser) *Conn {
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return newHybiConn(config, buf, rwc, nil)
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}
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// A HybiServerHandshaker performs a server handshake using hybi draft protocol.
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type hybiServerHandshaker struct {
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*Config
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accept []byte
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}
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func (c *hybiServerHandshaker) ReadHandshake(buf *bufio.Reader, req *http.Request) (code int, err error) {
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c.Version = ProtocolVersionHybi13
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if req.Method != "GET" {
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return http.StatusMethodNotAllowed, ErrBadRequestMethod
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}
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// HTTP version can be safely ignored.
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if strings.ToLower(req.Header.Get("Upgrade")) != "websocket" ||
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!strings.Contains(strings.ToLower(req.Header.Get("Connection")), "upgrade") {
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return http.StatusBadRequest, ErrNotWebSocket
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}
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key := req.Header.Get("Sec-Websocket-Key")
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if key == "" {
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return http.StatusBadRequest, ErrChallengeResponse
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}
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version := req.Header.Get("Sec-Websocket-Version")
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switch version {
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case "13":
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c.Version = ProtocolVersionHybi13
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default:
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return http.StatusBadRequest, ErrBadWebSocketVersion
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}
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var scheme string
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if req.TLS != nil {
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scheme = "wss"
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} else {
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scheme = "ws"
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}
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c.Location, err = url.ParseRequestURI(scheme + "://" + req.Host + req.URL.RequestURI())
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if err != nil {
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return http.StatusBadRequest, err
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}
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protocol := strings.TrimSpace(req.Header.Get("Sec-Websocket-Protocol"))
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if protocol != "" {
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protocols := strings.Split(protocol, ",")
|
|
for i := 0; i < len(protocols); i++ {
|
|
c.Protocol = append(c.Protocol, strings.TrimSpace(protocols[i]))
|
|
}
|
|
}
|
|
c.accept, err = getNonceAccept([]byte(key))
|
|
if err != nil {
|
|
return http.StatusInternalServerError, err
|
|
}
|
|
return http.StatusSwitchingProtocols, nil
|
|
}
|
|
|
|
// Origin parses the Origin header in req.
|
|
// If the Origin header is not set, it returns nil and nil.
|
|
func Origin(config *Config, req *http.Request) (*url.URL, error) {
|
|
var origin string
|
|
switch config.Version {
|
|
case ProtocolVersionHybi13:
|
|
origin = req.Header.Get("Origin")
|
|
}
|
|
if origin == "" {
|
|
return nil, nil
|
|
}
|
|
return url.ParseRequestURI(origin)
|
|
}
|
|
|
|
func (c *hybiServerHandshaker) AcceptHandshake(buf *bufio.Writer) (err error) {
|
|
if len(c.Protocol) > 0 {
|
|
if len(c.Protocol) != 1 {
|
|
// You need choose a Protocol in Handshake func in Server.
|
|
return ErrBadWebSocketProtocol
|
|
}
|
|
}
|
|
buf.WriteString("HTTP/1.1 101 Switching Protocols\r\n")
|
|
buf.WriteString("Upgrade: websocket\r\n")
|
|
buf.WriteString("Connection: Upgrade\r\n")
|
|
buf.WriteString("Sec-WebSocket-Accept: " + string(c.accept) + "\r\n")
|
|
if len(c.Protocol) > 0 {
|
|
buf.WriteString("Sec-WebSocket-Protocol: " + c.Protocol[0] + "\r\n")
|
|
}
|
|
// TODO(ukai): send Sec-WebSocket-Extensions.
|
|
if c.Header != nil {
|
|
err := c.Header.WriteSubset(buf, handshakeHeader)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
}
|
|
buf.WriteString("\r\n")
|
|
return buf.Flush()
|
|
}
|
|
|
|
func (c *hybiServerHandshaker) NewServerConn(buf *bufio.ReadWriter, rwc io.ReadWriteCloser, request *http.Request) *Conn {
|
|
return newHybiServerConn(c.Config, buf, rwc, request)
|
|
}
|
|
|
|
// newHybiServerConn returns a new WebSocket connection speaking hybi draft protocol.
|
|
func newHybiServerConn(config *Config, buf *bufio.ReadWriter, rwc io.ReadWriteCloser, request *http.Request) *Conn {
|
|
return newHybiConn(config, buf, rwc, request)
|
|
}
|