|
1 // Copyright 2013 The Gorilla WebSocket Authors. All rights reserved. |
|
2 // Use of this source code is governed by a BSD-style |
|
3 // license that can be found in the LICENSE file. |
|
4 |
|
5 // Package websocket implements the WebSocket protocol defined in RFC 6455. |
|
6 // |
|
7 // Overview |
|
8 // |
|
9 // The Conn type represents a WebSocket connection. A server application calls |
|
10 // the Upgrader.Upgrade method from an HTTP request handler to get a *Conn: |
|
11 // |
|
12 // var upgrader = websocket.Upgrader{ |
|
13 // ReadBufferSize: 1024, |
|
14 // WriteBufferSize: 1024, |
|
15 // } |
|
16 // |
|
17 // func handler(w http.ResponseWriter, r *http.Request) { |
|
18 // conn, err := upgrader.Upgrade(w, r, nil) |
|
19 // if err != nil { |
|
20 // log.Println(err) |
|
21 // return |
|
22 // } |
|
23 // ... Use conn to send and receive messages. |
|
24 // } |
|
25 // |
|
26 // Call the connection's WriteMessage and ReadMessage methods to send and |
|
27 // receive messages as a slice of bytes. This snippet of code shows how to echo |
|
28 // messages using these methods: |
|
29 // |
|
30 // for { |
|
31 // messageType, p, err := conn.ReadMessage() |
|
32 // if err != nil { |
|
33 // log.Println(err) |
|
34 // return |
|
35 // } |
|
36 // if err := conn.WriteMessage(messageType, p); err != nil { |
|
37 // log.Println(err) |
|
38 // return |
|
39 // } |
|
40 // } |
|
41 // |
|
42 // In above snippet of code, p is a []byte and messageType is an int with value |
|
43 // websocket.BinaryMessage or websocket.TextMessage. |
|
44 // |
|
45 // An application can also send and receive messages using the io.WriteCloser |
|
46 // and io.Reader interfaces. To send a message, call the connection NextWriter |
|
47 // method to get an io.WriteCloser, write the message to the writer and close |
|
48 // the writer when done. To receive a message, call the connection NextReader |
|
49 // method to get an io.Reader and read until io.EOF is returned. This snippet |
|
50 // shows how to echo messages using the NextWriter and NextReader methods: |
|
51 // |
|
52 // for { |
|
53 // messageType, r, err := conn.NextReader() |
|
54 // if err != nil { |
|
55 // return |
|
56 // } |
|
57 // w, err := conn.NextWriter(messageType) |
|
58 // if err != nil { |
|
59 // return err |
|
60 // } |
|
61 // if _, err := io.Copy(w, r); err != nil { |
|
62 // return err |
|
63 // } |
|
64 // if err := w.Close(); err != nil { |
|
65 // return err |
|
66 // } |
|
67 // } |
|
68 // |
|
69 // Data Messages |
|
70 // |
|
71 // The WebSocket protocol distinguishes between text and binary data messages. |
|
72 // Text messages are interpreted as UTF-8 encoded text. The interpretation of |
|
73 // binary messages is left to the application. |
|
74 // |
|
75 // This package uses the TextMessage and BinaryMessage integer constants to |
|
76 // identify the two data message types. The ReadMessage and NextReader methods |
|
77 // return the type of the received message. The messageType argument to the |
|
78 // WriteMessage and NextWriter methods specifies the type of a sent message. |
|
79 // |
|
80 // It is the application's responsibility to ensure that text messages are |
|
81 // valid UTF-8 encoded text. |
|
82 // |
|
83 // Control Messages |
|
84 // |
|
85 // The WebSocket protocol defines three types of control messages: close, ping |
|
86 // and pong. Call the connection WriteControl, WriteMessage or NextWriter |
|
87 // methods to send a control message to the peer. |
|
88 // |
|
89 // Connections handle received close messages by calling the handler function |
|
90 // set with the SetCloseHandler method and by returning a *CloseError from the |
|
91 // NextReader, ReadMessage or the message Read method. The default close |
|
92 // handler sends a close message to the peer. |
|
93 // |
|
94 // Connections handle received ping messages by calling the handler function |
|
95 // set with the SetPingHandler method. The default ping handler sends a pong |
|
96 // message to the peer. |
|
97 // |
|
98 // Connections handle received pong messages by calling the handler function |
|
99 // set with the SetPongHandler method. The default pong handler does nothing. |
|
100 // If an application sends ping messages, then the application should set a |
|
101 // pong handler to receive the corresponding pong. |
|
102 // |
|
103 // The control message handler functions are called from the NextReader, |
|
104 // ReadMessage and message reader Read methods. The default close and ping |
|
105 // handlers can block these methods for a short time when the handler writes to |
|
106 // the connection. |
|
107 // |
|
108 // The application must read the connection to process close, ping and pong |
|
109 // messages sent from the peer. If the application is not otherwise interested |
|
110 // in messages from the peer, then the application should start a goroutine to |
|
111 // read and discard messages from the peer. A simple example is: |
|
112 // |
|
113 // func readLoop(c *websocket.Conn) { |
|
114 // for { |
|
115 // if _, _, err := c.NextReader(); err != nil { |
|
116 // c.Close() |
|
117 // break |
|
118 // } |
|
119 // } |
|
120 // } |
|
121 // |
|
122 // Concurrency |
|
123 // |
|
124 // Connections support one concurrent reader and one concurrent writer. |
|
125 // |
|
126 // Applications are responsible for ensuring that no more than one goroutine |
|
127 // calls the write methods (NextWriter, SetWriteDeadline, WriteMessage, |
|
128 // WriteJSON, EnableWriteCompression, SetCompressionLevel) concurrently and |
|
129 // that no more than one goroutine calls the read methods (NextReader, |
|
130 // SetReadDeadline, ReadMessage, ReadJSON, SetPongHandler, SetPingHandler) |
|
131 // concurrently. |
|
132 // |
|
133 // The Close and WriteControl methods can be called concurrently with all other |
|
134 // methods. |
|
135 // |
|
136 // Origin Considerations |
|
137 // |
|
138 // Web browsers allow Javascript applications to open a WebSocket connection to |
|
139 // any host. It's up to the server to enforce an origin policy using the Origin |
|
140 // request header sent by the browser. |
|
141 // |
|
142 // The Upgrader calls the function specified in the CheckOrigin field to check |
|
143 // the origin. If the CheckOrigin function returns false, then the Upgrade |
|
144 // method fails the WebSocket handshake with HTTP status 403. |
|
145 // |
|
146 // If the CheckOrigin field is nil, then the Upgrader uses a safe default: fail |
|
147 // the handshake if the Origin request header is present and the Origin host is |
|
148 // not equal to the Host request header. |
|
149 // |
|
150 // The deprecated package-level Upgrade function does not perform origin |
|
151 // checking. The application is responsible for checking the Origin header |
|
152 // before calling the Upgrade function. |
|
153 // |
|
154 // Compression EXPERIMENTAL |
|
155 // |
|
156 // Per message compression extensions (RFC 7692) are experimentally supported |
|
157 // by this package in a limited capacity. Setting the EnableCompression option |
|
158 // to true in Dialer or Upgrader will attempt to negotiate per message deflate |
|
159 // support. |
|
160 // |
|
161 // var upgrader = websocket.Upgrader{ |
|
162 // EnableCompression: true, |
|
163 // } |
|
164 // |
|
165 // If compression was successfully negotiated with the connection's peer, any |
|
166 // message received in compressed form will be automatically decompressed. |
|
167 // All Read methods will return uncompressed bytes. |
|
168 // |
|
169 // Per message compression of messages written to a connection can be enabled |
|
170 // or disabled by calling the corresponding Conn method: |
|
171 // |
|
172 // conn.EnableWriteCompression(false) |
|
173 // |
|
174 // Currently this package does not support compression with "context takeover". |
|
175 // This means that messages must be compressed and decompressed in isolation, |
|
176 // without retaining sliding window or dictionary state across messages. For |
|
177 // more details refer to RFC 7692. |
|
178 // |
|
179 // Use of compression is experimental and may result in decreased performance. |
|
180 package websocket |