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// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Package websocket implements a client and server for the WebSocket protocol
// as specified in RFC 6455.
//
// This package currently lacks some features found in an alternative
// and more actively maintained WebSocket package:
//
// https://godoc.org/github.com/gorilla/websocket
//
package websocket // import "golang.org/x/net/websocket"
import (
"bufio"
"crypto/tls"
"encoding/json"
"errors"
"io"
"io/ioutil"
"net"
"net/http"
"net/url"
"sync"
"time"
)
const (
ProtocolVersionHybi13 = 13
ProtocolVersionHybi = ProtocolVersionHybi13
SupportedProtocolVersion = "13"
ContinuationFrame = 0
TextFrame = 1
BinaryFrame = 2
CloseFrame = 8
PingFrame = 9
PongFrame = 10
UnknownFrame = 255
DefaultMaxPayloadBytes = 32 << 20 // 32MB
)
// ProtocolError represents WebSocket protocol errors.
type ProtocolError struct {
ErrorString string
}
func (err *ProtocolError) Error() string { return err.ErrorString }
var (
ErrBadProtocolVersion = &ProtocolError{"bad protocol version"}
ErrBadScheme = &ProtocolError{"bad scheme"}
ErrBadStatus = &ProtocolError{"bad status"}
ErrBadUpgrade = &ProtocolError{"missing or bad upgrade"}
ErrBadWebSocketOrigin = &ProtocolError{"missing or bad WebSocket-Origin"}
ErrBadWebSocketLocation = &ProtocolError{"missing or bad WebSocket-Location"}
ErrBadWebSocketProtocol = &ProtocolError{"missing or bad WebSocket-Protocol"}
ErrBadWebSocketVersion = &ProtocolError{"missing or bad WebSocket Version"}
ErrChallengeResponse = &ProtocolError{"mismatch challenge/response"}
ErrBadFrame = &ProtocolError{"bad frame"}
ErrBadFrameBoundary = &ProtocolError{"not on frame boundary"}
ErrNotWebSocket = &ProtocolError{"not websocket protocol"}
ErrBadRequestMethod = &ProtocolError{"bad method"}
ErrNotSupported = &ProtocolError{"not supported"}
)
// ErrFrameTooLarge is returned by Codec's Receive method if payload size
// exceeds limit set by Conn.MaxPayloadBytes
var ErrFrameTooLarge = errors.New("websocket: frame payload size exceeds limit")
// Addr is an implementation of net.Addr for WebSocket.
type Addr struct {
*url.URL
}
// Network returns the network type for a WebSocket, "websocket".
func (addr *Addr) Network() string { return "websocket" }
// Config is a WebSocket configuration
type Config struct {
// A WebSocket server address.
Location *url.URL
// A Websocket client origin.
Origin *url.URL
// WebSocket subprotocols.
Protocol []string
// WebSocket protocol version.
Version int
// TLS config for secure WebSocket (wss).
TlsConfig *tls.Config
// Additional header fields to be sent in WebSocket opening handshake.
Header http.Header
// Dialer used when opening websocket connections.
Dialer *net.Dialer
handshakeData map[string]string
}
// serverHandshaker is an interface to handle WebSocket server side handshake.
type serverHandshaker interface {
// ReadHandshake reads handshake request message from client.
// Returns http response code and error if any.
ReadHandshake(buf *bufio.Reader, req *http.Request) (code int, err error)
// AcceptHandshake accepts the client handshake request and sends
// handshake response back to client.
AcceptHandshake(buf *bufio.Writer) (err error)
// NewServerConn creates a new WebSocket connection.
NewServerConn(buf *bufio.ReadWriter, rwc io.ReadWriteCloser, request *http.Request) (conn *Conn)
}
// frameReader is an interface to read a WebSocket frame.
type frameReader interface {
// Reader is to read payload of the frame.
io.Reader
// PayloadType returns payload type.
PayloadType() byte
// HeaderReader returns a reader to read header of the frame.
HeaderReader() io.Reader
// TrailerReader returns a reader to read trailer of the frame.
// If it returns nil, there is no trailer in the frame.
TrailerReader() io.Reader
// Len returns total length of the frame, including header and trailer.
Len() int
}
// frameReaderFactory is an interface to creates new frame reader.
type frameReaderFactory interface {
NewFrameReader() (r frameReader, err error)
}
// frameWriter is an interface to write a WebSocket frame.
type frameWriter interface {
// Writer is to write payload of the frame.
io.WriteCloser
}
// frameWriterFactory is an interface to create new frame writer.
type frameWriterFactory interface {
NewFrameWriter(payloadType byte) (w frameWriter, err error)
}
type frameHandler interface {
HandleFrame(frame frameReader) (r frameReader, err error)
WriteClose(status int) (err error)
}
// Conn represents a WebSocket connection.
//
// Multiple goroutines may invoke methods on a Conn simultaneously.
type Conn struct {
config *Config
request *http.Request
buf *bufio.ReadWriter
rwc io.ReadWriteCloser
rio sync.Mutex
frameReaderFactory
frameReader
wio sync.Mutex
frameWriterFactory
frameHandler
PayloadType byte
defaultCloseStatus int
// MaxPayloadBytes limits the size of frame payload received over Conn
// by Codec's Receive method. If zero, DefaultMaxPayloadBytes is used.
MaxPayloadBytes int
}
// Read implements the io.Reader interface:
// it reads data of a frame from the WebSocket connection.
// if msg is not large enough for the frame data, it fills the msg and next Read
// will read the rest of the frame data.
// it reads Text frame or Binary frame.
func (ws *Conn) Read(msg []byte) (n int, err error) {
ws.rio.Lock()
defer ws.rio.Unlock()
again:
if ws.frameReader == nil {
frame, err := ws.frameReaderFactory.NewFrameReader()
if err != nil {
return 0, err
}
ws.frameReader, err = ws.frameHandler.HandleFrame(frame)
if err != nil {
return 0, err
}
if ws.frameReader == nil {
goto again
}
}
n, err = ws.frameReader.Read(msg)
if err == io.EOF {
if trailer := ws.frameReader.TrailerReader(); trailer != nil {
io.Copy(ioutil.Discard, trailer)
}
ws.frameReader = nil
goto again
}
return n, err
}
// Write implements the io.Writer interface:
// it writes data as a frame to the WebSocket connection.
func (ws *Conn) Write(msg []byte) (n int, err error) {
ws.wio.Lock()
defer ws.wio.Unlock()
w, err := ws.frameWriterFactory.NewFrameWriter(ws.PayloadType)
if err != nil {
return 0, err
}
n, err = w.Write(msg)
w.Close()
return n, err
}
// Close implements the io.Closer interface.
func (ws *Conn) Close() error {
err := ws.frameHandler.WriteClose(ws.defaultCloseStatus)
err1 := ws.rwc.Close()
if err != nil {
return err
}
return err1
}
// IsClientConn reports whether ws is a client-side connection.
func (ws *Conn) IsClientConn() bool { return ws.request == nil }
// IsServerConn reports whether ws is a server-side connection.
func (ws *Conn) IsServerConn() bool { return ws.request != nil }
// LocalAddr returns the WebSocket Origin for the connection for client, or
// the WebSocket location for server.
func (ws *Conn) LocalAddr() net.Addr {
if ws.IsClientConn() {
return &Addr{ws.config.Origin}
}
return &Addr{ws.config.Location}
}
// RemoteAddr returns the WebSocket location for the connection for client, or
// the Websocket Origin for server.
func (ws *Conn) RemoteAddr() net.Addr {
if ws.IsClientConn() {
return &Addr{ws.config.Location}
}
return &Addr{ws.config.Origin}
}
var errSetDeadline = errors.New("websocket: cannot set deadline: not using a net.Conn")
// SetDeadline sets the connection's network read & write deadlines.
func (ws *Conn) SetDeadline(t time.Time) error {
if conn, ok := ws.rwc.(net.Conn); ok {
return conn.SetDeadline(t)
}
return errSetDeadline
}
// SetReadDeadline sets the connection's network read deadline.
func (ws *Conn) SetReadDeadline(t time.Time) error {
if conn, ok := ws.rwc.(net.Conn); ok {
return conn.SetReadDeadline(t)
}
return errSetDeadline
}
// SetWriteDeadline sets the connection's network write deadline.
func (ws *Conn) SetWriteDeadline(t time.Time) error {
if conn, ok := ws.rwc.(net.Conn); ok {
return conn.SetWriteDeadline(t)
}
return errSetDeadline
}
// Config returns the WebSocket config.
func (ws *Conn) Config() *Config { return ws.config }
// Request returns the http request upgraded to the WebSocket.
// It is nil for client side.
func (ws *Conn) Request() *http.Request { return ws.request }
// Codec represents a symmetric pair of functions that implement a codec.
type Codec struct {
Marshal func(v interface{}) (data []byte, payloadType byte, err error)
Unmarshal func(data []byte, payloadType byte, v interface{}) (err error)
}
// Send sends v marshaled by cd.Marshal as single frame to ws.
func (cd Codec) Send(ws *Conn, v interface{}) (err error) {
data, payloadType, err := cd.Marshal(v)
if err != nil {
return err
}
ws.wio.Lock()
defer ws.wio.Unlock()
w, err := ws.frameWriterFactory.NewFrameWriter(payloadType)
if err != nil {
return err
}
_, err = w.Write(data)
w.Close()
return err
}
// Receive receives single frame from ws, unmarshaled by cd.Unmarshal and stores
// in v. The whole frame payload is read to an in-memory buffer; max size of
// payload is defined by ws.MaxPayloadBytes. If frame payload size exceeds
// limit, ErrFrameTooLarge is returned; in this case frame is not read off wire
// completely. The next call to Receive would read and discard leftover data of
// previous oversized frame before processing next frame.
func (cd Codec) Receive(ws *Conn, v interface{}) (err error) {
ws.rio.Lock()
defer ws.rio.Unlock()
if ws.frameReader != nil {
_, err = io.Copy(ioutil.Discard, ws.frameReader)
if err != nil {
return err
}
ws.frameReader = nil
}
again:
frame, err := ws.frameReaderFactory.NewFrameReader()
if err != nil {
return err
}
frame, err = ws.frameHandler.HandleFrame(frame)
if err != nil {
return err
}
if frame == nil {
goto again
}
maxPayloadBytes := ws.MaxPayloadBytes
if maxPayloadBytes == 0 {
maxPayloadBytes = DefaultMaxPayloadBytes
}
if hf, ok := frame.(*hybiFrameReader); ok && hf.header.Length > int64(maxPayloadBytes) {
// payload size exceeds limit, no need to call Unmarshal
//
// set frameReader to current oversized frame so that
// the next call to this function can drain leftover
// data before processing the next frame
ws.frameReader = frame
return ErrFrameTooLarge
}
payloadType := frame.PayloadType()
data, err := ioutil.ReadAll(frame)
if err != nil {
return err
}
return cd.Unmarshal(data, payloadType, v)
}
func marshal(v interface{}) (msg []byte, payloadType byte, err error) {
switch data := v.(type) {
case string:
return []byte(data), TextFrame, nil
case []byte:
return data, BinaryFrame, nil
}
return nil, UnknownFrame, ErrNotSupported
}
func unmarshal(msg []byte, payloadType byte, v interface{}) (err error) {
switch data := v.(type) {
case *string:
*data = string(msg)
return nil
case *[]byte:
*data = msg
return nil
}
return ErrNotSupported
}
/*
Message is a codec to send/receive text/binary data in a frame on WebSocket connection.
To send/receive text frame, use string type.
To send/receive binary frame, use []byte type.
Trivial usage:
import "websocket"
// receive text frame
var message string
websocket.Message.Receive(ws, &message)
// send text frame
message = "hello"
websocket.Message.Send(ws, message)
// receive binary frame
var data []byte
websocket.Message.Receive(ws, &data)
// send binary frame
data = []byte{0, 1, 2}
websocket.Message.Send(ws, data)
*/
var Message = Codec{marshal, unmarshal}
func jsonMarshal(v interface{}) (msg []byte, payloadType byte, err error) {
msg, err = json.Marshal(v)
return msg, TextFrame, err
}
func jsonUnmarshal(msg []byte, payloadType byte, v interface{}) (err error) {
return json.Unmarshal(msg, v)
}
/*
JSON is a codec to send/receive JSON data in a frame from a WebSocket connection.
Trivial usage:
import "websocket"
type T struct {
Msg string
Count int
}
// receive JSON type T
var data T
websocket.JSON.Receive(ws, &data)
// send JSON type T
websocket.JSON.Send(ws, data)
*/
var JSON = Codec{jsonMarshal, jsonUnmarshal}