| // Copyright 2013 The Gorilla WebSocket 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 the WebSocket protocol defined in RFC 6455. |
| // |
| // Overview |
| // |
| // The Conn type represents a WebSocket connection. A server application calls |
| // the Upgrader.Upgrade method from an HTTP request handler to get a *Conn: |
| // |
| // var upgrader = websocket.Upgrader{ |
| // ReadBufferSize: 1024, |
| // WriteBufferSize: 1024, |
| // } |
| // |
| // func handler(w http.ResponseWriter, r *http.Request) { |
| // conn, err := upgrader.Upgrade(w, r, nil) |
| // if err != nil { |
| // log.Println(err) |
| // return |
| // } |
| // ... Use conn to send and receive messages. |
| // } |
| // |
| // Call the connection's WriteMessage and ReadMessage methods to send and |
| // receive messages as a slice of bytes. This snippet of code shows how to echo |
| // messages using these methods: |
| // |
| // for { |
| // messageType, p, err := conn.ReadMessage() |
| // if err != nil { |
| // return |
| // } |
| // if err := conn.WriteMessage(messageType, p); err != nil { |
| // return err |
| // } |
| // } |
| // |
| // In above snippet of code, p is a []byte and messageType is an int with value |
| // websocket.BinaryMessage or websocket.TextMessage. |
| // |
| // An application can also send and receive messages using the io.WriteCloser |
| // and io.Reader interfaces. To send a message, call the connection NextWriter |
| // method to get an io.WriteCloser, write the message to the writer and close |
| // the writer when done. To receive a message, call the connection NextReader |
| // method to get an io.Reader and read until io.EOF is returned. This snippet |
| // shows how to echo messages using the NextWriter and NextReader methods: |
| // |
| // for { |
| // messageType, r, err := conn.NextReader() |
| // if err != nil { |
| // return |
| // } |
| // w, err := conn.NextWriter(messageType) |
| // if err != nil { |
| // return err |
| // } |
| // if _, err := io.Copy(w, r); err != nil { |
| // return err |
| // } |
| // if err := w.Close(); err != nil { |
| // return err |
| // } |
| // } |
| // |
| // Data Messages |
| // |
| // The WebSocket protocol distinguishes between text and binary data messages. |
| // Text messages are interpreted as UTF-8 encoded text. The interpretation of |
| // binary messages is left to the application. |
| // |
| // This package uses the TextMessage and BinaryMessage integer constants to |
| // identify the two data message types. The ReadMessage and NextReader methods |
| // return the type of the received message. The messageType argument to the |
| // WriteMessage and NextWriter methods specifies the type of a sent message. |
| // |
| // It is the application's responsibility to ensure that text messages are |
| // valid UTF-8 encoded text. |
| // |
| // Control Messages |
| // |
| // The WebSocket protocol defines three types of control messages: close, ping |
| // and pong. Call the connection WriteControl, WriteMessage or NextWriter |
| // methods to send a control message to the peer. |
| // |
| // Connections handle received close messages by sending a close message to the |
| // peer and returning a *CloseError from the the NextReader, ReadMessage or the |
| // message Read method. |
| // |
| // Connections handle received ping and pong messages by invoking callback |
| // functions set with SetPingHandler and SetPongHandler methods. The callback |
| // functions are called from the NextReader, ReadMessage and the message Read |
| // methods. |
| // |
| // The default ping handler sends a pong to the peer. The application's reading |
| // goroutine can block for a short time while the handler writes the pong data |
| // to the connection. |
| // |
| // The application must read the connection to process ping, pong and close |
| // messages sent from the peer. If the application is not otherwise interested |
| // in messages from the peer, then the application should start a goroutine to |
| // read and discard messages from the peer. A simple example is: |
| // |
| // func readLoop(c *websocket.Conn) { |
| // for { |
| // if _, _, err := c.NextReader(); err != nil { |
| // c.Close() |
| // break |
| // } |
| // } |
| // } |
| // |
| // Concurrency |
| // |
| // Connections support one concurrent reader and one concurrent writer. |
| // |
| // Applications are responsible for ensuring that no more than one goroutine |
| // calls the write methods (NextWriter, SetWriteDeadline, WriteMessage, |
| // WriteJSON, EnableWriteCompression, SetCompressionLevel) concurrently and |
| // that no more than one goroutine calls the read methods (NextReader, |
| // SetReadDeadline, ReadMessage, ReadJSON, SetPongHandler, SetPingHandler) |
| // concurrently. |
| // |
| // The Close and WriteControl methods can be called concurrently with all other |
| // methods. |
| // |
| // Origin Considerations |
| // |
| // Web browsers allow Javascript applications to open a WebSocket connection to |
| // any host. It's up to the server to enforce an origin policy using the Origin |
| // request header sent by the browser. |
| // |
| // The Upgrader calls the function specified in the CheckOrigin field to check |
| // the origin. If the CheckOrigin function returns false, then the Upgrade |
| // method fails the WebSocket handshake with HTTP status 403. |
| // |
| // If the CheckOrigin field is nil, then the Upgrader uses a safe default: fail |
| // the handshake if the Origin request header is present and not equal to the |
| // Host request header. |
| // |
| // An application can allow connections from any origin by specifying a |
| // function that always returns true: |
| // |
| // var upgrader = websocket.Upgrader{ |
| // CheckOrigin: func(r *http.Request) bool { return true }, |
| // } |
| // |
| // The deprecated package-level Upgrade function does not perform origin |
| // checking. The application is responsible for checking the Origin header |
| // before calling the Upgrade function. |
| // |
| // Compression EXPERIMENTAL |
| // |
| // Per message compression extensions (RFC 7692) are experimentally supported |
| // by this package in a limited capacity. Setting the EnableCompression option |
| // to true in Dialer or Upgrader will attempt to negotiate per message deflate |
| // support. |
| // |
| // var upgrader = websocket.Upgrader{ |
| // EnableCompression: true, |
| // } |
| // |
| // If compression was successfully negotiated with the connection's peer, any |
| // message received in compressed form will be automatically decompressed. |
| // All Read methods will return uncompressed bytes. |
| // |
| // Per message compression of messages written to a connection can be enabled |
| // or disabled by calling the corresponding Conn method: |
| // |
| // conn.EnableWriteCompression(false) |
| // |
| // Currently this package does not support compression with "context takeover". |
| // This means that messages must be compressed and decompressed in isolation, |
| // without retaining sliding window or dictionary state across messages. For |
| // more details refer to RFC 7692. |
| // |
| // Use of compression is experimental and may result in decreased performance. |
| package websocket |