README
¶
Gorilla WebSocket
Gorilla WebSocket is a Go implementation of the WebSocket protocol.
Documentation
Status
The Gorilla WebSocket package provides a complete and tested implementation of the WebSocket protocol. The package API is stable.
Installation
go get github.com/gorilla/websocket
Protocol Compliance
The Gorilla WebSocket package passes the server tests in the Autobahn WebSockets Test Suite using the application in the examples/autobahn subdirectory.
Gorilla WebSocket compared with other packages
| gorilla | go.net | |
|---|---|---|
| Protocol support | RFC 6455 | RFC 6455 |
| Limit size of received message | Yes | No |
| Send pings and receive pongs | Yes | No |
| Send close message | Yes | No |
| Read message using io.Reader | Yes | No, see note |
| Write message using io.WriteCloser | Yes | No, see note |
| Encode, decode JSON message | Yes | Yes |
Note: The go.net io.Reader and io.Writer operate across WebSocket message boundaries. Read returns when the input buffer is full or a message boundary is encountered, Each call to Write sends a message. The Gorilla io.Reader and io.WriteCloser operate on a single WebSocket message.
Documentation
¶
Overview ¶
Package websocket implements the WebSocket protocol defined in RFC 6455.
Overview ¶
The Conn type represents a WebSocket connection. A server application calls the Upgrade function from an HTTP request handler to get a pointer to a Conn:
func handler(w http.ResponseWriter, r *http.Request) {
conn, err := websocket.Upgrade(w, r.Header, nil, 1024, 1024)
if _, ok := err.(websocket.HandshakeError); ok {
http.Error(w, "Not a websocket handshake", 400)
return
} else if err != nil {
log.Println(err)
return
}
... Use conn to send and receive messages.
}
Call the connection WriteMessage and ReadMessages 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.WriteMessaage(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 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 ping and pong messages by invoking a callback function set with SetPingHandler and SetPongHandler methods. These callback functions can be invoked from the ReadMessage method, the NextReader method or from a call to the data message reader returned from NextReader.
Connections handle received close messages by returning an error from the ReadMessage method, the NextReader method or from a call to the data message reader returned from NextReader.
Concurrency ¶
A Conn supports a single concurrent caller to the write methods (NextWriter, SetWriteDeadline, WriteMessage) and a single concurrent caller to the read methods (NextReader, SetReadDeadline, ReadMessage). The Close and WriteControl methods can be called concurrently with all other methods.
Index ¶
- Constants
- Variables
- func FormatCloseMessage(closeCode int, text string) []byte
- func ReadJSON(c *Conn, v interface{}) error
- func Subprotocols(r *http.Request) []string
- func WriteJSON(c *Conn, v interface{}) error
- type Conn
- func (c *Conn) Close() error
- func (c *Conn) LocalAddr() net.Addr
- func (c *Conn) NextReader() (messageType int, r io.Reader, err error)
- func (c *Conn) NextWriter(messageType int) (io.WriteCloser, error)
- func (c *Conn) ReadJSON(v interface{}) error
- func (c *Conn) ReadMessage() (messageType int, p []byte, err error)
- func (c *Conn) RemoteAddr() net.Addr
- func (c *Conn) SetPingHandler(h func(string) error)
- func (c *Conn) SetPongHandler(h func(string) error)
- func (c *Conn) SetReadDeadline(t time.Time) error
- func (c *Conn) SetReadLimit(limit int64)
- func (c *Conn) SetWriteDeadline(t time.Time) error
- func (c *Conn) WriteControl(messageType int, data []byte, deadline time.Time) error
- func (c *Conn) WriteJSON(v interface{}) error
- func (c *Conn) WriteMessage(messageType int, data []byte) error
- type HandshakeError
Constants ¶
const ( CloseNormalClosure = 1000 CloseGoingAway = 1001 CloseProtocolError = 1002 CloseUnsupportedData = 1003 CloseNoStatusReceived = 1005 CloseAbnormalClosure = 1006 CloseInvalidFramePayloadData = 1007 ClosePolicyViolation = 1008 CloseMessageTooBig = 1009 CloseMandatoryExtension = 1010 CloseInternalServerErr = 1011 CloseTLSHandshake = 1015 )
Close codes defined in RFC 6455, section 11.7.
const ( // TextMessage denotes a text data message. The text message payload is // interpreted as UTF-8 encoded text data. TextMessage = 1 // BinaryMessage denotes a binary data message. BinaryMessage = 2 // CloseMessage denotes a close control message. The optional message // payload contains a numeric code and text. Use the FormatCloseMessage // function to format a close message payload. CloseMessage = 8 // PingMessage denotes a ping control message. The optional message payload // is UTF-8 encoded text. PingMessage = 9 // PongMessage denotes a ping control message. The optional message payload // is UTF-8 encoded text. PongMessage = 10 )
The message types are defined in RFC 6455, section 11.8.
Variables ¶
var ( ErrCloseSent = errors.New("websocket: close sent") ErrReadLimit = errors.New("websocket: read limit exceeded") )
var ErrBadHandshake = errors.New("websocket: bad handshake")
ErrBadHandshake is returned when the server response to opening handshake is invalid.
Functions ¶
func FormatCloseMessage ¶
SetPongHandler sets the handler for FormatCloseMessage formats closeCode and text as a WebSocket close message.
func Subprotocols ¶
Subprotocols returns the subprotocols requested by the client in the Sec-Websocket-Protocol header.
Types ¶
type Conn ¶
type Conn struct {
// contains filtered or unexported fields
}
Conn represents a WebSocket connection.
func NewClient ¶
func NewClient(netConn net.Conn, u *url.URL, requestHeader http.Header, readBufSize, writeBufSize int) (c *Conn, response *http.Response, err error)
NewClient creates a new client connection using the given net connection. The URL u specifies the host and request URI. Use requestHeader to specify the origin (Origin), subprotocols (Set-WebSocket-Protocol) and cookies (Cookie). Use the response.Header to get the selected subprotocol (Sec-WebSocket-Protocol) and cookies (Set-Cookie).
If the WebSocket handshake fails, ErrBadHandshake is returned along with a non-nil *http.Response so that callers can handle redirects, authentication, etc.
func Upgrade ¶
func Upgrade(w http.ResponseWriter, r *http.Request, responseHeader http.Header, readBufSize, writeBufSize int) (*Conn, error)
Upgrade upgrades the HTTP server connection to the WebSocket protocol.
The application is responsible for checking the request origin before calling Upgrade. An example implementation of the same origin policy is:
if req.Header.Get("Origin") != "http://"+req.Host {
http.Error(w, "Origin not allowed", 403)
return
}
If the endpoint supports WebSocket subprotocols, then the application is responsible for selecting a subprotocol that is acceptable to the client and echoing that value back to the client. Use the Subprotocols function to get the list of protocols specified by the client. Use the Sec-Websocket-Protocol response header to echo the selected protocol back to the client.
Appilcations can set cookies by adding a Set-Cookie header to the response header.
If the request is not a valid WebSocket handshake, then Upgrade returns an error of type HandshakeError. Applications should handle this error by replying to the client with an HTTP error response.
func (*Conn) Close ¶
Close closes the underlying network connection without sending or waiting for a close frame.
func (*Conn) NextReader ¶
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 (*Conn) NextWriter ¶
func (c *Conn) NextWriter(messageType int) (io.WriteCloser, error)
NextWriter returns a writer for the next message to send. The writer's Close method flushes the complete message to the network.
There can be at most one open writer on a connection. NextWriter closes the previous writer if the application has not already done so.
The NextWriter method and the writers returned from the method cannot be accessed by more than one goroutine at a time.
func (*Conn) ReadJSON ¶
ReadJSON reads the next JSON-encoded message from the connection and stores it in the value pointed to by v.
See the documentation for the encoding/json Marshal function for details about the conversion of JSON to a Go value.
func (*Conn) ReadMessage ¶
ReadMessage is a helper method for getting a reader using NextReader and reading from that reader to a buffer.
func (*Conn) RemoteAddr ¶
RemoteAddr returns the remote network address.
func (*Conn) SetPingHandler ¶
SetPingHandler sets the handler for ping messages received from the peer. The default ping handler sends a pong to the peer.
func (*Conn) SetPongHandler ¶
SetPongHandler sets then handler for pong messages received from the peer. The default pong handler does nothing.
func (*Conn) SetReadDeadline ¶
SetReadDeadline sets the deadline for future calls to NextReader and the io.Reader returned from NextReader. If the deadline is reached, the call will fail with a timeout instead of blocking. A zero value for t means that the methods will not time out.
func (*Conn) SetReadLimit ¶
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 (*Conn) SetWriteDeadline ¶
SetWriteDeadline sets the deadline for future calls to NextWriter and the io.WriteCloser returned from NextWriter. If the deadline is reached, the call will fail with a timeout instead of blocking. A zero value for t means Write will not time out. Even if Write times out, it may return n > 0, indicating that some of the data was successfully written.
func (*Conn) WriteControl ¶
WriteControl writes a control message with the given deadline. The allowed message types are CloseMessage, PingMessage and PongMessage.
type HandshakeError ¶
type HandshakeError struct {
// contains filtered or unexported fields
}
HandshakeError describes an error with the handshake from the peer.
func (HandshakeError) Error ¶
func (e HandshakeError) Error() string
Source Files