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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
import (
"bufio"
"fmt"
"io"
"net/http"
)
func newServerConn(rwc io.ReadWriteCloser, buf *bufio.ReadWriter, req *http.Request, config *Config, handshake func(*Config, *http.Request) error) (conn *Conn, err error) {
var hs serverHandshaker = &hybiServerHandshaker{Config: config}
code, err := hs.ReadHandshake(buf.Reader, req)
if err == ErrBadWebSocketVersion {
fmt.Fprintf(buf, "HTTP/1.1 %03d %s\r\n", code, http.StatusText(code))
fmt.Fprintf(buf, "Sec-WebSocket-Version: %s\r\n", SupportedProtocolVersion)
buf.WriteString("\r\n")
buf.WriteString(err.Error())
buf.Flush()
return
}
if err != nil {
fmt.Fprintf(buf, "HTTP/1.1 %03d %s\r\n", code, http.StatusText(code))
buf.WriteString("\r\n")
buf.WriteString(err.Error())
buf.Flush()
return
}
if handshake != nil {
err = handshake(config, req)
if err != nil {
code = http.StatusForbidden
fmt.Fprintf(buf, "HTTP/1.1 %03d %s\r\n", code, http.StatusText(code))
buf.WriteString("\r\n")
buf.Flush()
return
}
}
err = hs.AcceptHandshake(buf.Writer)
if err != nil {
code = http.StatusBadRequest
fmt.Fprintf(buf, "HTTP/1.1 %03d %s\r\n", code, http.StatusText(code))
buf.WriteString("\r\n")
buf.Flush()
return
}
conn = hs.NewServerConn(buf, rwc, req)
return
}
// Server represents a server of a WebSocket.
type Server struct {
// Config is a WebSocket configuration for new WebSocket connection.
Config
// Handshake is an optional function in WebSocket handshake.
// For example, you can check, or don't check Origin header.
// Another example, you can select config.Protocol.
Handshake func(*Config, *http.Request) error
// Handler handles a WebSocket connection.
Handler
}
// ServeHTTP implements the http.Handler interface for a WebSocket
func (s Server) ServeHTTP(w http.ResponseWriter, req *http.Request) {
s.serveWebSocket(w, req)
}
func (s Server) serveWebSocket(w http.ResponseWriter, req *http.Request) {
rwc, buf, err := w.(http.Hijacker).Hijack()
if err != nil {
panic("Hijack failed: " + err.Error())
}
// The server should abort the WebSocket connection if it finds
// the client did not send a handshake that matches with protocol
// specification.
defer rwc.Close()
conn, err := newServerConn(rwc, buf, req, &s.Config, s.Handshake)
if err != nil {
return
}
if conn == nil {
panic("unexpected nil conn")
}
s.Handler(conn)
}
// Handler is a simple interface to a WebSocket browser client.
// It checks if Origin header is valid URL by default.
// You might want to verify websocket.Conn.Config().Origin in the func.
// If you use Server instead of Handler, you could call websocket.Origin and
// check the origin in your Handshake func. So, if you want to accept
// non-browser clients, which do not send an Origin header, set a
// Server.Handshake that does not check the origin.
type Handler func(*Conn)
func checkOrigin(config *Config, req *http.Request) (err error) {
config.Origin, err = Origin(config, req)
if err == nil && config.Origin == nil {
return fmt.Errorf("null origin")
}
return err
}
// ServeHTTP implements the http.Handler interface for a WebSocket
func (h Handler) ServeHTTP(w http.ResponseWriter, req *http.Request) {
s := Server{Handler: h, Handshake: checkOrigin}
s.serveWebSocket(w, req)
}