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181 lines
6.8 KiB
Go
181 lines
6.8 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 implements the WebSocket protocol defined in RFC 6455.
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//
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// Overview
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//
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// The Conn type represents a WebSocket connection. A server application uses
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// the Upgrade function from an Upgrader object with a HTTP request handler
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// to get a pointer to a Conn:
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//
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// var upgrader = websocket.Upgrader{
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// ReadBufferSize: 1024,
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// WriteBufferSize: 1024,
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// }
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//
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// func handler(w http.ResponseWriter, r *http.Request) {
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// conn, err := upgrader.Upgrade(w, r, nil)
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// if err != nil {
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// log.Println(err)
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// return
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// }
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// ... Use conn to send and receive messages.
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// }
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//
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// Call the connection's WriteMessage and ReadMessage methods to send and
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// receive messages as a slice of bytes. This snippet of code shows how to echo
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// messages using these methods:
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//
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// for {
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// messageType, p, err := conn.ReadMessage()
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// if err != nil {
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// return
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// }
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// if err = conn.WriteMessage(messageType, p); err != nil {
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// return err
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// }
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// }
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//
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// In above snippet of code, p is a []byte and messageType is an int with value
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// websocket.BinaryMessage or websocket.TextMessage.
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//
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// An application can also send and receive messages using the io.WriteCloser
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// and io.Reader interfaces. To send a message, call the connection NextWriter
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// method to get an io.WriteCloser, write the message to the writer and close
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// the writer when done. To receive a message, call the connection NextReader
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// method to get an io.Reader and read until io.EOF is returned. This snippet
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// shows how to echo messages using the NextWriter and NextReader methods:
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//
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// for {
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// messageType, r, err := conn.NextReader()
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// if err != nil {
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// return
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// }
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// w, err := conn.NextWriter(messageType)
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// if err != nil {
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// return err
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// }
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// if _, err := io.Copy(w, r); err != nil {
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// return err
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// }
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// if err := w.Close(); err != nil {
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// return err
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// }
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// }
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//
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// Data Messages
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//
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// The WebSocket protocol distinguishes between text and binary data messages.
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// Text messages are interpreted as UTF-8 encoded text. The interpretation of
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// binary messages is left to the application.
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//
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// This package uses the TextMessage and BinaryMessage integer constants to
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// identify the two data message types. The ReadMessage and NextReader methods
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// return the type of the received message. The messageType argument to the
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// WriteMessage and NextWriter methods specifies the type of a sent message.
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//
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// It is the application's responsibility to ensure that text messages are
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// valid UTF-8 encoded text.
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//
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// Control Messages
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//
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// The WebSocket protocol defines three types of control messages: close, ping
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// and pong. Call the connection WriteControl, WriteMessage or NextWriter
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// methods to send a control message to the peer.
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//
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// Connections handle received close messages by sending a close message to the
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// peer and returning a *CloseError from the the NextReader, ReadMessage or the
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// message Read method.
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//
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// Connections handle received ping and pong messages by invoking callback
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// functions set with SetPingHandler and SetPongHandler methods. The callback
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// functions are called from the NextReader, ReadMessage and the message Read
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// methods.
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//
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// The default ping handler sends a pong to the peer. The application's reading
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// goroutine can block for a short time while the handler writes the pong data
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// to the connection.
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//
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// The application must read the connection to process ping, pong and close
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// messages sent from the peer. If the application is not otherwise interested
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// in messages from the peer, then the application should start a goroutine to
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// read and discard messages from the peer. A simple example is:
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//
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// func readLoop(c *websocket.Conn) {
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// for {
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// if _, _, err := c.NextReader(); err != nil {
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// c.Close()
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// break
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// }
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// }
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// }
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//
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// Concurrency
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//
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// Connections support one concurrent reader and one concurrent writer.
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//
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// Applications are responsible for ensuring that no more than one goroutine
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// calls the write methods (NextWriter, SetWriteDeadline, WriteMessage,
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// WriteJSON, EnableWriteCompression, SetCompressionLevel) concurrently and
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// that no more than one goroutine calls the read methods (NextReader,
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// SetReadDeadline, ReadMessage, ReadJSON, SetPongHandler, SetPingHandler)
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// concurrently.
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//
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// The Close and WriteControl methods can be called concurrently with all other
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// methods.
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//
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// Origin Considerations
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//
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// Web browsers allow Javascript applications to open a WebSocket connection to
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// any host. It's up to the server to enforce an origin policy using the Origin
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// request header sent by the browser.
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//
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// The Upgrader calls the function specified in the CheckOrigin field to check
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// the origin. If the CheckOrigin function returns false, then the Upgrade
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// method fails the WebSocket handshake with HTTP status 403.
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//
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// If the CheckOrigin field is nil, then the Upgrader uses a safe default: fail
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// the handshake if the Origin request header is present and not equal to the
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// Host request header.
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//
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// An application can allow connections from any origin by specifying a
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// function that always returns true:
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//
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// var upgrader = websocket.Upgrader{
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// CheckOrigin: func(r *http.Request) bool { return true },
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// }
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//
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// The deprecated Upgrade function does not enforce an origin policy. It's the
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// application's responsibility to check the Origin header before calling
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// Upgrade.
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//
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// Compression EXPERIMENTAL
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//
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// Per message compression extensions (RFC 7692) are experimentally supported
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// by this package in a limited capacity. Setting the EnableCompression option
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// to true in Dialer or Upgrader will attempt to negotiate per message deflate
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// support.
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//
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// var upgrader = websocket.Upgrader{
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// EnableCompression: true,
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// }
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//
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// If compression was successfully negotiated with the connection's peer, any
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// message received in compressed form will be automatically decompressed.
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// All Read methods will return uncompressed bytes.
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//
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// Per message compression of messages written to a connection can be enabled
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// or disabled by calling the corresponding Conn method:
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//
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// conn.EnableWriteCompression(false)
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//
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// Currently this package does not support compression with "context takeover".
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// This means that messages must be compressed and decompressed in isolation,
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// without retaining sliding window or dictionary state across messages. For
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// more details refer to RFC 7692.
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//
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// Use of compression is experimental and may result in decreased performance.
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package websocket
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