826 lines
20 KiB
Go
826 lines
20 KiB
Go
// Copyright 2013 The Gorilla WebSocket 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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import (
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"bufio"
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"encoding/binary"
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"errors"
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"io"
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"io/ioutil"
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"math/rand"
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"net"
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"strconv"
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"time"
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)
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const (
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maxFrameHeaderSize = 2 + 8 + 4 // Fixed header + length + mask
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maxControlFramePayloadSize = 125
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finalBit = 1 << 7
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maskBit = 1 << 7
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writeWait = time.Second
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defaultReadBufferSize = 4096
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defaultWriteBufferSize = 4096
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continuationFrame = 0
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noFrame = -1
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)
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// Close codes defined in RFC 6455, section 11.7.
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const (
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CloseNormalClosure = 1000
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CloseGoingAway = 1001
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CloseProtocolError = 1002
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CloseUnsupportedData = 1003
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CloseNoStatusReceived = 1005
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CloseAbnormalClosure = 1006
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CloseInvalidFramePayloadData = 1007
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ClosePolicyViolation = 1008
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CloseMessageTooBig = 1009
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CloseMandatoryExtension = 1010
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CloseInternalServerErr = 1011
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CloseTLSHandshake = 1015
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)
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// The message types are defined in RFC 6455, section 11.8.
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const (
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// TextMessage denotes a text data message. The text message payload is
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// interpreted as UTF-8 encoded text data.
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TextMessage = 1
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// BinaryMessage denotes a binary data message.
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BinaryMessage = 2
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// CloseMessage denotes a close control message. The optional message
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// payload contains a numeric code and text. Use the FormatCloseMessage
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// function to format a close message payload.
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CloseMessage = 8
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// PingMessage denotes a ping control message. The optional message payload
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// is UTF-8 encoded text.
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PingMessage = 9
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// PongMessage denotes a ping control message. The optional message payload
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// is UTF-8 encoded text.
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PongMessage = 10
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)
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// ErrCloseSent is returned when the application writes a message to the
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// connection after sending a close message.
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var ErrCloseSent = errors.New("websocket: close sent")
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// ErrReadLimit is returned when reading a message that is larger than the
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// read limit set for the connection.
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var ErrReadLimit = errors.New("websocket: read limit exceeded")
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// netError satisfies the net Error interface.
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type netError struct {
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msg string
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temporary bool
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timeout bool
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}
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func (e *netError) Error() string { return e.msg }
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func (e *netError) Temporary() bool { return e.temporary }
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func (e *netError) Timeout() bool { return e.timeout }
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// closeError represents close frame.
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type closeError struct {
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code int
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text string
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}
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func (e *closeError) Error() string {
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return "websocket: close " + strconv.Itoa(e.code) + " " + e.text
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}
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var (
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errWriteTimeout = &netError{msg: "websocket: write timeout", timeout: true}
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errUnexpectedEOF = &closeError{code: CloseAbnormalClosure, text: io.ErrUnexpectedEOF.Error()}
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errBadWriteOpCode = errors.New("websocket: bad write message type")
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errWriteClosed = errors.New("websocket: write closed")
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errInvalidControlFrame = errors.New("websocket: invalid control frame")
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)
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func hideTempErr(err error) error {
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if e, ok := err.(net.Error); ok && e.Temporary() {
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err = &netError{msg: e.Error(), timeout: e.Timeout()}
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}
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return err
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}
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func isControl(frameType int) bool {
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return frameType == CloseMessage || frameType == PingMessage || frameType == PongMessage
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}
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func isData(frameType int) bool {
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return frameType == TextMessage || frameType == BinaryMessage
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}
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func maskBytes(key [4]byte, pos int, b []byte) int {
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for i := range b {
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b[i] ^= key[pos&3]
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pos++
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}
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return pos & 3
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}
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func newMaskKey() [4]byte {
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n := rand.Uint32()
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return [4]byte{byte(n), byte(n >> 8), byte(n >> 16), byte(n >> 24)}
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}
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// Conn represents a WebSocket connection.
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type Conn struct {
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conn net.Conn
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isServer bool
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subprotocol string
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// Write fields
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mu chan bool // used as mutex to protect write to conn and closeSent
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closeSent bool // true if close message was sent
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// Message writer fields.
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writeErr error
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writeBuf []byte // frame is constructed in this buffer.
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writePos int // end of data in writeBuf.
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writeFrameType int // type of the current frame.
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writeSeq int // incremented to invalidate message writers.
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writeDeadline time.Time
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// Read fields
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readErr error
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br *bufio.Reader
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readRemaining int64 // bytes remaining in current frame.
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readFinal bool // true the current message has more frames.
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readSeq int // incremented to invalidate message readers.
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readLength int64 // Message size.
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readLimit int64 // Maximum message size.
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readMaskPos int
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readMaskKey [4]byte
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handlePong func(string) error
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handlePing func(string) error
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}
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func newConn(conn net.Conn, isServer bool, readBufferSize, writeBufferSize int) *Conn {
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mu := make(chan bool, 1)
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mu <- true
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if readBufferSize == 0 {
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readBufferSize = defaultReadBufferSize
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}
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if writeBufferSize == 0 {
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writeBufferSize = defaultWriteBufferSize
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}
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c := &Conn{
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isServer: isServer,
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br: bufio.NewReaderSize(conn, readBufferSize),
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conn: conn,
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mu: mu,
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readFinal: true,
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writeBuf: make([]byte, writeBufferSize+maxFrameHeaderSize),
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writeFrameType: noFrame,
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writePos: maxFrameHeaderSize,
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}
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c.SetPingHandler(nil)
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c.SetPongHandler(nil)
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return c
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}
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// Subprotocol returns the negotiated protocol for the connection.
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func (c *Conn) Subprotocol() string {
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return c.subprotocol
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}
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// Close closes the underlying network connection without sending or waiting for a close frame.
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func (c *Conn) Close() error {
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return c.conn.Close()
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}
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// LocalAddr returns the local network address.
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func (c *Conn) LocalAddr() net.Addr {
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return c.conn.LocalAddr()
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}
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// RemoteAddr returns the remote network address.
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func (c *Conn) RemoteAddr() net.Addr {
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return c.conn.RemoteAddr()
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}
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// Write methods
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func (c *Conn) write(frameType int, deadline time.Time, bufs ...[]byte) error {
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<-c.mu
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defer func() { c.mu <- true }()
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if c.closeSent {
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return ErrCloseSent
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} else if frameType == CloseMessage {
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c.closeSent = true
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}
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c.conn.SetWriteDeadline(deadline)
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for _, buf := range bufs {
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if len(buf) > 0 {
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n, err := c.conn.Write(buf)
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if n != len(buf) {
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// Close on partial write.
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c.conn.Close()
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}
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if err != nil {
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return err
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}
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}
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}
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return nil
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}
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// WriteControl writes a control message with the given deadline. The allowed
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// message types are CloseMessage, PingMessage and PongMessage.
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func (c *Conn) WriteControl(messageType int, data []byte, deadline time.Time) error {
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if !isControl(messageType) {
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return errBadWriteOpCode
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}
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if len(data) > maxControlFramePayloadSize {
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return errInvalidControlFrame
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}
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b0 := byte(messageType) | finalBit
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b1 := byte(len(data))
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if !c.isServer {
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b1 |= maskBit
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}
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buf := make([]byte, 0, maxFrameHeaderSize+maxControlFramePayloadSize)
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buf = append(buf, b0, b1)
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if c.isServer {
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buf = append(buf, data...)
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} else {
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key := newMaskKey()
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buf = append(buf, key[:]...)
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buf = append(buf, data...)
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maskBytes(key, 0, buf[6:])
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}
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d := time.Hour * 1000
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if !deadline.IsZero() {
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d = deadline.Sub(time.Now())
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if d < 0 {
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return errWriteTimeout
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}
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}
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timer := time.NewTimer(d)
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select {
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case <-c.mu:
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timer.Stop()
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case <-timer.C:
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return errWriteTimeout
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}
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defer func() { c.mu <- true }()
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if c.closeSent {
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return ErrCloseSent
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} else if messageType == CloseMessage {
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c.closeSent = true
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}
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c.conn.SetWriteDeadline(deadline)
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n, err := c.conn.Write(buf)
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if n != 0 && n != len(buf) {
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c.conn.Close()
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}
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return err
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}
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// NextWriter returns a writer for the next message to send. The writer's
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// Close method flushes the complete message to the network.
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//
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// There can be at most one open writer on a connection. NextWriter closes the
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// previous writer if the application has not already done so.
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//
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// The NextWriter method and the writers returned from the method cannot be
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// accessed by more than one goroutine at a time.
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func (c *Conn) NextWriter(messageType int) (io.WriteCloser, error) {
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if c.writeErr != nil {
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return nil, c.writeErr
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}
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if c.writeFrameType != noFrame {
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if err := c.flushFrame(true, nil); err != nil {
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return nil, err
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}
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}
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if !isControl(messageType) && !isData(messageType) {
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return nil, errBadWriteOpCode
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}
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c.writeFrameType = messageType
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return messageWriter{c, c.writeSeq}, nil
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}
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func (c *Conn) flushFrame(final bool, extra []byte) error {
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length := c.writePos - maxFrameHeaderSize + len(extra)
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// Check for invalid control frames.
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if isControl(c.writeFrameType) &&
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(!final || length > maxControlFramePayloadSize) {
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c.writeSeq++
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c.writeFrameType = noFrame
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c.writePos = maxFrameHeaderSize
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return errInvalidControlFrame
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}
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b0 := byte(c.writeFrameType)
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if final {
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b0 |= finalBit
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}
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b1 := byte(0)
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if !c.isServer {
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b1 |= maskBit
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}
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// Assume that the frame starts at beginning of c.writeBuf.
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framePos := 0
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if c.isServer {
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// Adjust up if mask not included in the header.
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framePos = 4
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}
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switch {
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case length >= 65536:
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c.writeBuf[framePos] = b0
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c.writeBuf[framePos+1] = b1 | 127
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binary.BigEndian.PutUint64(c.writeBuf[framePos+2:], uint64(length))
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case length > 125:
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framePos += 6
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c.writeBuf[framePos] = b0
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c.writeBuf[framePos+1] = b1 | 126
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binary.BigEndian.PutUint16(c.writeBuf[framePos+2:], uint16(length))
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default:
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framePos += 8
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c.writeBuf[framePos] = b0
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c.writeBuf[framePos+1] = b1 | byte(length)
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}
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if !c.isServer {
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key := newMaskKey()
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copy(c.writeBuf[maxFrameHeaderSize-4:], key[:])
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maskBytes(key, 0, c.writeBuf[maxFrameHeaderSize:c.writePos])
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if len(extra) > 0 {
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c.writeErr = errors.New("websocket: internal error, extra used in client mode")
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return c.writeErr
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}
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}
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// Write the buffers to the connection.
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c.writeErr = c.write(c.writeFrameType, c.writeDeadline, c.writeBuf[framePos:c.writePos], extra)
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// Setup for next frame.
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c.writePos = maxFrameHeaderSize
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c.writeFrameType = continuationFrame
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if final {
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c.writeSeq++
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c.writeFrameType = noFrame
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}
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return c.writeErr
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}
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type messageWriter struct {
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c *Conn
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seq int
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}
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func (w messageWriter) err() error {
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c := w.c
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if c.writeSeq != w.seq {
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return errWriteClosed
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}
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if c.writeErr != nil {
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return c.writeErr
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}
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return nil
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}
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func (w messageWriter) ncopy(max int) (int, error) {
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n := len(w.c.writeBuf) - w.c.writePos
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if n <= 0 {
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if err := w.c.flushFrame(false, nil); err != nil {
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return 0, err
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}
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n = len(w.c.writeBuf) - w.c.writePos
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}
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if n > max {
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n = max
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}
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return n, nil
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}
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func (w messageWriter) write(final bool, p []byte) (int, error) {
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if err := w.err(); err != nil {
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return 0, err
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}
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if len(p) > 2*len(w.c.writeBuf) && w.c.isServer {
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// Don't buffer large messages.
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err := w.c.flushFrame(final, p)
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if err != nil {
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return 0, err
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}
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return len(p), nil
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}
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nn := len(p)
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for len(p) > 0 {
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n, err := w.ncopy(len(p))
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if err != nil {
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return 0, err
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}
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copy(w.c.writeBuf[w.c.writePos:], p[:n])
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w.c.writePos += n
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p = p[n:]
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}
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return nn, nil
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}
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func (w messageWriter) Write(p []byte) (int, error) {
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return w.write(false, p)
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}
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func (w messageWriter) WriteString(p string) (int, error) {
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if err := w.err(); err != nil {
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return 0, err
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}
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nn := len(p)
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for len(p) > 0 {
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n, err := w.ncopy(len(p))
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if err != nil {
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return 0, err
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}
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copy(w.c.writeBuf[w.c.writePos:], p[:n])
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w.c.writePos += n
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p = p[n:]
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}
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return nn, nil
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}
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func (w messageWriter) ReadFrom(r io.Reader) (nn int64, err error) {
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if err := w.err(); err != nil {
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return 0, err
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}
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for {
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if w.c.writePos == len(w.c.writeBuf) {
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err = w.c.flushFrame(false, nil)
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if err != nil {
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break
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}
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}
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var n int
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n, err = r.Read(w.c.writeBuf[w.c.writePos:])
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w.c.writePos += n
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nn += int64(n)
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if err != nil {
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if err == io.EOF {
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err = nil
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}
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break
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}
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}
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return nn, err
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}
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func (w messageWriter) Close() error {
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if err := w.err(); err != nil {
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return err
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}
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return w.c.flushFrame(true, nil)
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}
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// WriteMessage is a helper method for getting a writer using NextWriter,
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// writing the message and closing the writer.
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func (c *Conn) WriteMessage(messageType int, data []byte) error {
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wr, err := c.NextWriter(messageType)
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if err != nil {
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return err
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}
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w := wr.(messageWriter)
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if _, err := w.write(true, data); err != nil {
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return err
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}
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if c.writeSeq == w.seq {
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if err := c.flushFrame(true, nil); err != nil {
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return err
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}
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}
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return nil
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}
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// SetWriteDeadline sets the write deadline on the underlying network
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// connection. After a write has timed out, the websocket state is corrupt and
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// all future writes will return an error. A zero value for t means writes will
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// not time out.
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func (c *Conn) SetWriteDeadline(t time.Time) error {
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c.writeDeadline = t
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return nil
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}
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|
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// Read methods
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// readFull is like io.ReadFull except that io.EOF is never returned.
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func (c *Conn) readFull(p []byte) (err error) {
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var n int
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for n < len(p) && err == nil {
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var nn int
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nn, err = c.br.Read(p[n:])
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n += nn
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}
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if n == len(p) {
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err = nil
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} else if err == io.EOF {
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err = errUnexpectedEOF
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}
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return
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}
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func (c *Conn) advanceFrame() (int, error) {
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// 1. Skip remainder of previous frame.
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if c.readRemaining > 0 {
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if _, err := io.CopyN(ioutil.Discard, c.br, c.readRemaining); err != nil {
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return noFrame, err
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}
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}
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// 2. Read and parse first two bytes of frame header.
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var b [8]byte
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if err := c.readFull(b[:2]); err != nil {
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return noFrame, err
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}
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final := b[0]&finalBit != 0
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frameType := int(b[0] & 0xf)
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reserved := int((b[0] >> 4) & 0x7)
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mask := b[1]&maskBit != 0
|
|
c.readRemaining = int64(b[1] & 0x7f)
|
|
|
|
if reserved != 0 {
|
|
return noFrame, c.handleProtocolError("unexpected reserved bits " + strconv.Itoa(reserved))
|
|
}
|
|
|
|
switch frameType {
|
|
case CloseMessage, PingMessage, PongMessage:
|
|
if c.readRemaining > maxControlFramePayloadSize {
|
|
return noFrame, c.handleProtocolError("control frame length > 125")
|
|
}
|
|
if !final {
|
|
return noFrame, c.handleProtocolError("control frame not final")
|
|
}
|
|
case TextMessage, BinaryMessage:
|
|
if !c.readFinal {
|
|
return noFrame, c.handleProtocolError("message start before final message frame")
|
|
}
|
|
c.readFinal = final
|
|
case continuationFrame:
|
|
if c.readFinal {
|
|
return noFrame, c.handleProtocolError("continuation after final message frame")
|
|
}
|
|
c.readFinal = final
|
|
default:
|
|
return noFrame, c.handleProtocolError("unknown opcode " + strconv.Itoa(frameType))
|
|
}
|
|
|
|
// 3. Read and parse frame length.
|
|
|
|
switch c.readRemaining {
|
|
case 126:
|
|
if err := c.readFull(b[:2]); err != nil {
|
|
return noFrame, err
|
|
}
|
|
c.readRemaining = int64(binary.BigEndian.Uint16(b[:2]))
|
|
case 127:
|
|
if err := c.readFull(b[:8]); err != nil {
|
|
return noFrame, err
|
|
}
|
|
c.readRemaining = int64(binary.BigEndian.Uint64(b[:8]))
|
|
}
|
|
|
|
// 4. Handle frame masking.
|
|
|
|
if mask != c.isServer {
|
|
return noFrame, c.handleProtocolError("incorrect mask flag")
|
|
}
|
|
|
|
if mask {
|
|
c.readMaskPos = 0
|
|
if err := c.readFull(c.readMaskKey[:]); err != nil {
|
|
return noFrame, err
|
|
}
|
|
}
|
|
|
|
// 5. For text and binary messages, enforce read limit and return.
|
|
|
|
if frameType == continuationFrame || frameType == TextMessage || frameType == BinaryMessage {
|
|
|
|
c.readLength += c.readRemaining
|
|
if c.readLimit > 0 && c.readLength > c.readLimit {
|
|
c.WriteControl(CloseMessage, FormatCloseMessage(CloseMessageTooBig, ""), time.Now().Add(writeWait))
|
|
return noFrame, ErrReadLimit
|
|
}
|
|
|
|
return frameType, nil
|
|
}
|
|
|
|
// 6. Read control frame payload.
|
|
|
|
var payload []byte
|
|
if c.readRemaining > 0 {
|
|
payload = make([]byte, c.readRemaining)
|
|
c.readRemaining = 0
|
|
if err := c.readFull(payload); err != nil {
|
|
return noFrame, err
|
|
}
|
|
if c.isServer {
|
|
maskBytes(c.readMaskKey, 0, payload)
|
|
}
|
|
}
|
|
|
|
// 7. Process control frame payload.
|
|
|
|
switch frameType {
|
|
case PongMessage:
|
|
if err := c.handlePong(string(payload)); err != nil {
|
|
return noFrame, err
|
|
}
|
|
case PingMessage:
|
|
if err := c.handlePing(string(payload)); err != nil {
|
|
return noFrame, err
|
|
}
|
|
case CloseMessage:
|
|
c.WriteControl(CloseMessage, []byte{}, time.Now().Add(writeWait))
|
|
closeCode := CloseNoStatusReceived
|
|
closeText := ""
|
|
if len(payload) >= 2 {
|
|
closeCode = int(binary.BigEndian.Uint16(payload))
|
|
closeText = string(payload[2:])
|
|
}
|
|
switch closeCode {
|
|
case CloseNormalClosure, CloseGoingAway:
|
|
return noFrame, io.EOF
|
|
default:
|
|
return noFrame, &closeError{code: closeCode, text: closeText}
|
|
}
|
|
}
|
|
|
|
return frameType, nil
|
|
}
|
|
|
|
func (c *Conn) handleProtocolError(message string) error {
|
|
c.WriteControl(CloseMessage, FormatCloseMessage(CloseProtocolError, message), time.Now().Add(writeWait))
|
|
return errors.New("websocket: " + message)
|
|
}
|
|
|
|
// NextReader returns the next data message received from the peer. The
|
|
// returned messageType is either TextMessage or BinaryMessage.
|
|
//
|
|
// There can be at most one open reader on a connection. NextReader discards
|
|
// the previous message if the application has not already consumed it.
|
|
//
|
|
// The NextReader method and the readers returned from the method cannot be
|
|
// accessed by more than one goroutine at a time.
|
|
func (c *Conn) NextReader() (messageType int, r io.Reader, err error) {
|
|
|
|
c.readSeq++
|
|
c.readLength = 0
|
|
|
|
for c.readErr == nil {
|
|
frameType, err := c.advanceFrame()
|
|
if err != nil {
|
|
c.readErr = hideTempErr(err)
|
|
break
|
|
}
|
|
if frameType == TextMessage || frameType == BinaryMessage {
|
|
return frameType, messageReader{c, c.readSeq}, nil
|
|
}
|
|
}
|
|
return noFrame, nil, c.readErr
|
|
}
|
|
|
|
type messageReader struct {
|
|
c *Conn
|
|
seq int
|
|
}
|
|
|
|
func (r messageReader) Read(b []byte) (int, error) {
|
|
|
|
if r.seq != r.c.readSeq {
|
|
return 0, io.EOF
|
|
}
|
|
|
|
for r.c.readErr == nil {
|
|
|
|
if r.c.readRemaining > 0 {
|
|
if int64(len(b)) > r.c.readRemaining {
|
|
b = b[:r.c.readRemaining]
|
|
}
|
|
n, err := r.c.br.Read(b)
|
|
r.c.readErr = hideTempErr(err)
|
|
if r.c.isServer {
|
|
r.c.readMaskPos = maskBytes(r.c.readMaskKey, r.c.readMaskPos, b[:n])
|
|
}
|
|
r.c.readRemaining -= int64(n)
|
|
return n, r.c.readErr
|
|
}
|
|
|
|
if r.c.readFinal {
|
|
r.c.readSeq++
|
|
return 0, io.EOF
|
|
}
|
|
|
|
frameType, err := r.c.advanceFrame()
|
|
switch {
|
|
case err != nil:
|
|
r.c.readErr = hideTempErr(err)
|
|
case frameType == TextMessage || frameType == BinaryMessage:
|
|
r.c.readErr = errors.New("websocket: internal error, unexpected text or binary in Reader")
|
|
}
|
|
}
|
|
|
|
err := r.c.readErr
|
|
if err == io.EOF && r.seq == r.c.readSeq {
|
|
err = errUnexpectedEOF
|
|
}
|
|
return 0, err
|
|
}
|
|
|
|
// ReadMessage is a helper method for getting a reader using NextReader and
|
|
// reading from that reader to a buffer.
|
|
func (c *Conn) ReadMessage() (messageType int, p []byte, err error) {
|
|
var r io.Reader
|
|
messageType, r, err = c.NextReader()
|
|
if err != nil {
|
|
return messageType, nil, err
|
|
}
|
|
p, err = ioutil.ReadAll(r)
|
|
return messageType, p, err
|
|
}
|
|
|
|
// SetReadDeadline sets the read deadline on the underlying network connection.
|
|
// After a read has timed out, the websocket connection state is corrupt and
|
|
// all future reads will return an error. A zero value for t means reads will
|
|
// not time out.
|
|
func (c *Conn) SetReadDeadline(t time.Time) error {
|
|
return c.conn.SetReadDeadline(t)
|
|
}
|
|
|
|
// SetReadLimit sets the maximum size for a message read from the peer. If a
|
|
// message exceeds the limit, the connection sends a close frame to the peer
|
|
// and returns ErrReadLimit to the application.
|
|
func (c *Conn) SetReadLimit(limit int64) {
|
|
c.readLimit = limit
|
|
}
|
|
|
|
// SetPingHandler sets the handler for ping messages received from the peer.
|
|
// The default ping handler sends a pong to the peer.
|
|
func (c *Conn) SetPingHandler(h func(string) error) {
|
|
if h == nil {
|
|
h = func(message string) error {
|
|
c.WriteControl(PongMessage, []byte(message), time.Now().Add(writeWait))
|
|
return nil
|
|
}
|
|
}
|
|
c.handlePing = h
|
|
}
|
|
|
|
// SetPongHandler sets the handler for pong messages received from the peer.
|
|
// The default pong handler does nothing.
|
|
func (c *Conn) SetPongHandler(h func(string) error) {
|
|
if h == nil {
|
|
h = func(string) error { return nil }
|
|
}
|
|
c.handlePong = h
|
|
}
|
|
|
|
// UnderlyingConn returns the internal net.Conn. This can be used to further
|
|
// modifications to connection specific flags.
|
|
func (c *Conn) UnderlyingConn() net.Conn {
|
|
return c.conn
|
|
}
|
|
|
|
// FormatCloseMessage formats closeCode and text as a WebSocket close message.
|
|
func FormatCloseMessage(closeCode int, text string) []byte {
|
|
buf := make([]byte, 2+len(text))
|
|
binary.BigEndian.PutUint16(buf, uint16(closeCode))
|
|
copy(buf[2:], text)
|
|
return buf
|
|
}
|