Add WebSocket server framework hooked into http.

R=r, rsc
https://golang.org/cl/156071

src/pkg/websocket/client.go

@@ -0,0 +1,136 @@
+// 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";
+	"http";
+	"io";
+	"net";
+	"os";
+)
+
+type ProtocolError struct {
+	os.ErrorString;
+}
+
+var (
+	ErrBadStatus		= &ProtocolError{"bad status"};
+	ErrNoUpgrade		= &ProtocolError{"no upgrade"};
+	ErrBadUpgrade		= &ProtocolError{"bad upgrade"};
+	ErrNoWebSocketOrigin	= &ProtocolError{"no WebSocket-Origin"};
+	ErrBadWebSocketOrigin	= &ProtocolError{"bad WebSocket-Origin"};
+	ErrNoWebSocketLocation	= &ProtocolError{"no WebSocket-Location"};
+	ErrBadWebSocketLocation	= &ProtocolError{"bad WebSocket-Location"};
+	ErrNoWebSocketProtocol	= &ProtocolError{"no WebSocket-Protocol"};
+	ErrBadWebSocketProtocol	= &ProtocolError{"bad WebSocket-Protocol"};
+)
+
+// newClient creates a new Web Socket client connection.
+func newClient(resourceName, host, origin, location, protocol string, rwc io.ReadWriteCloser) (ws *Conn, err os.Error) {
+	br := bufio.NewReader(rwc);
+	bw := bufio.NewWriter(rwc);
+	err = handshake(resourceName, host, origin, location, protocol, br, bw);
+	if err != nil {
+		return
+	}
+	buf := bufio.NewReadWriter(br, bw);
+	ws = newConn(origin, location, protocol, buf, rwc);
+	return;
+}
+
+// Dial opens new Web Socket client connection.
+//
+// A trivial example client is:
+//
+// package main
+//
+// import (
+//  "websocket"
+//  "strings"
+// )
+//
+// func main() {
+//    ws, err := websocket.Dial("ws://localhost/ws", "", "http://localhost/");
+//    if err != nil {
+//        panic("Dial: ", err.String())
+//    }
+//    if _, err := ws.Write(strings.Bytes("hello, world!\n")); err != nil {
+//        panic("Write: ", err.String())
+//    }
+//    var msg = make([]byte, 512);
+//    if n, err := ws.Read(msg); err != nil {
+//        panic("Read: ", err.String())
+//    }
+//    // msg[0:n]
+// }
+
+func Dial(url, protocol, origin string) (ws *Conn, err os.Error) {
+	parsedUrl, err := http.ParseURL(url);
+	if err != nil {
+		return
+	}
+	client, err := net.Dial("tcp", "", parsedUrl.Host);
+	if err != nil {
+		return
+	}
+	return newClient(parsedUrl.Path, parsedUrl.Host, origin, url, protocol, client);
+}
+
+func handshake(resourceName, host, origin, location, protocol string, br *bufio.Reader, bw *bufio.Writer) (err os.Error) {
+	bw.WriteString("GET " + resourceName + " HTTP/1.1\r\n");
+	bw.WriteString("Upgrade: WebSocket\r\n");
+	bw.WriteString("Connection: Upgrade\r\n");
+	bw.WriteString("Host: " + host + "\r\n");
+	bw.WriteString("Origin: " + origin + "\r\n");
+	if protocol != "" {
+		bw.WriteString("WebSocket-Protocol: " + protocol + "\r\n")
+	}
+	bw.WriteString("\r\n");
+	bw.Flush();
+	resp, err := http.ReadResponse(br);
+	if err != nil {
+		return
+	}
+	if resp.Status != "101 Web Socket Protocol Handshake" {
+		return ErrBadStatus
+	}
+	upgrade, found := resp.Header["Upgrade"];
+	if !found {
+		return ErrNoUpgrade
+	}
+	if upgrade != "WebSocket" {
+		return ErrBadUpgrade
+	}
+	connection, found := resp.Header["Connection"];
+	if !found || connection != "Upgrade" {
+		return ErrBadUpgrade
+	}
+
+	ws_origin, found := resp.Header["Websocket-Origin"];
+	if !found {
+		return ErrNoWebSocketOrigin
+	}
+	if ws_origin != origin {
+		return ErrBadWebSocketOrigin
+	}
+	ws_location, found := resp.Header["Websocket-Location"];
+	if !found {
+		return ErrNoWebSocketLocation
+	}
+	if ws_location != location {
+		return ErrBadWebSocketLocation
+	}
+	if protocol != "" {
+		ws_protocol, found := resp.Header["Websocket-Protocol"];
+		if !found {
+			return ErrNoWebSocketProtocol
+		}
+		if ws_protocol != protocol {
+			return ErrBadWebSocketProtocol
+		}
+	}
+	return;
+}