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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 (
"http"
"io"
"strings"
)
/*
Handler is an interface to a WebSocket.
A trivial example server:
package main
import (
"http"
"io"
"websocket"
)
// Echo the data received on the Web Socket.
func EchoServer(ws *websocket.Conn) {
io.Copy(ws, ws);
}
func main() {
http.Handle("/echo", websocket.Handler(EchoServer));
err := http.ListenAndServe(":12345", nil);
if err != nil {
panic("ListenAndServe: " + err.String())
}
}
*/
type Handler func(*Conn)
/*
Gets key number from Sec-WebSocket-Key<n>: field as described
in 5.2 Sending the server's opening handshake, 4.
*/
func getKeyNumber(s string) (r uint32) {
// 4. Let /key-number_n/ be the digits (characters in the range
// U+0030 DIGIT ZERO (0) to U+0039 DIGIT NINE (9)) in /key_1/,
// interpreted as a base ten integer, ignoring all other characters
// in /key_n/.
r = 0
for i := 0; i < len(s); i++ {
if s[i] >= '0' && s[i] <= '9' {
r = r*10 + uint32(s[i]) - '0'
}
}
return
}
// ServeHTTP implements the http.Handler interface for a Web Socket
func (f Handler) ServeHTTP(w http.ResponseWriter, req *http.Request) {
rwc, buf, err := w.Hijack()
if err != nil {
panic("Hijack failed: " + err.String())
return
}
// 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()
if req.Method != "GET" {
return
}
// HTTP version can be safely ignored.
if strings.ToLower(req.Header["Upgrade"]) != "websocket" ||
strings.ToLower(req.Header["Connection"]) != "upgrade" {
return
}
// TODO(ukai): check Host
origin, found := req.Header["Origin"]
if !found {
return
}
key1, found := req.Header["Sec-Websocket-Key1"]
if !found {
return
}
key2, found := req.Header["Sec-Websocket-Key2"]
if !found {
return
}
key3 := make([]byte, 8)
if _, err := io.ReadFull(buf, key3); err != nil {
return
}
var location string
if w.UsingTLS() {
location = "wss://" + req.Host + req.URL.RawPath
} else {
location = "ws://" + req.Host + req.URL.RawPath
}
// Step 4. get key number in Sec-WebSocket-Key<n> fields.
keyNumber1 := getKeyNumber(key1)
keyNumber2 := getKeyNumber(key2)
// Step 5. get number of spaces in Sec-WebSocket-Key<n> fields.
space1 := uint32(strings.Count(key1, " "))
space2 := uint32(strings.Count(key2, " "))
if space1 == 0 || space2 == 0 {
return
}
// Step 6. key number must be an integral multiple of spaces.
if keyNumber1%space1 != 0 || keyNumber2%space2 != 0 {
return
}
// Step 7. let part be key number divided by spaces.
part1 := keyNumber1 / space1
part2 := keyNumber2 / space2
// Step 8. let challenge to be concatination of part1, part2 and key3.
// Step 9. get MD5 fingerprint of challenge.
response, err := getChallengeResponse(part1, part2, key3)
if err != nil {
return
}
// Step 10. send response status line.
buf.WriteString("HTTP/1.1 101 WebSocket Protocol Handshake\r\n")
// Step 11. send response headers.
buf.WriteString("Upgrade: WebSocket\r\n")
buf.WriteString("Connection: Upgrade\r\n")
buf.WriteString("Sec-WebSocket-Location: " + location + "\r\n")
buf.WriteString("Sec-WebSocket-Origin: " + origin + "\r\n")
protocol, found := req.Header["Sec-Websocket-Protocol"]
if found {
buf.WriteString("Sec-WebSocket-Protocol: " + protocol + "\r\n")
}
// Step 12. send CRLF.
buf.WriteString("\r\n")
// Step 13. send response data.
buf.Write(response)
if err := buf.Flush(); err != nil {
return
}
ws := newConn(origin, location, protocol, buf, rwc)
f(ws)
}
/*
Draft75Handler is an interface to a WebSocket based on the
(soon obsolete) draft-hixie-thewebsocketprotocol-75.
*/
type Draft75Handler func(*Conn)
// ServeHTTP implements the http.Handler interface for a Web Socket.
func (f Draft75Handler) ServeHTTP(w http.ResponseWriter, req *http.Request) {
if req.Method != "GET" || req.Proto != "HTTP/1.1" {
w.WriteHeader(http.StatusBadRequest)
io.WriteString(w, "Unexpected request")
return
}
if req.Header["Upgrade"] != "WebSocket" {
w.WriteHeader(http.StatusBadRequest)
io.WriteString(w, "missing Upgrade: WebSocket header")
return
}
if req.Header["Connection"] != "Upgrade" {
w.WriteHeader(http.StatusBadRequest)
io.WriteString(w, "missing Connection: Upgrade header")
return
}
origin, found := req.Header["Origin"]
if !found {
w.WriteHeader(http.StatusBadRequest)
io.WriteString(w, "missing Origin header")
return
}
rwc, buf, err := w.Hijack()
if err != nil {
panic("Hijack failed: " + err.String())
return
}
defer rwc.Close()
var location string
if w.UsingTLS() {
location = "wss://" + req.Host + req.URL.RawPath
} else {
location = "ws://" + req.Host + req.URL.RawPath
}
// TODO(ukai): verify origin,location,protocol.
buf.WriteString("HTTP/1.1 101 Web Socket Protocol Handshake\r\n")
buf.WriteString("Upgrade: WebSocket\r\n")
buf.WriteString("Connection: Upgrade\r\n")
buf.WriteString("WebSocket-Origin: " + origin + "\r\n")
buf.WriteString("WebSocket-Location: " + location + "\r\n")
protocol, found := req.Header["Websocket-Protocol"]
// canonical header key of WebSocket-Protocol.
if found {
buf.WriteString("WebSocket-Protocol: " + protocol + "\r\n")
}
buf.WriteString("\r\n")
if err := buf.Flush(); err != nil {
return
}
ws := newConn(origin, location, protocol, buf, rwc)
f(ws)
}
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