websocket: Add support for secure WebSockets

Fixes #842.
Fixes #1061.

R=rsc
CC=golang-dev
https://golang.org/cl/2119042

src/pkg/http/server.go

@@ -63,6 +63,7 @@ type Conn struct {
 	header          map[string]string // reply header parameters
 	written         int64             // number of bytes written in body
 	status          int               // status code passed to WriteHeader
+	usingTLS        bool              // a flag indicating connection over TLS
 }
 
 // Create new connection from rwc.
@@ -73,6 +74,7 @@ func newConn(rwc net.Conn, handler Handler) (c *Conn, err os.Error) {
 	}
 	c.handler = handler
 	c.rwc = rwc
+	_, c.usingTLS = rwc.(*tls.Conn)
 	br := bufio.NewReader(rwc)
 	bw := bufio.NewWriter(rwc)
 	c.buf = bufio.NewReadWriter(br, bw)
@@ -151,6 +153,11 @@ func (c *Conn) readRequest() (req *Request, err os.Error) {
 	return req, nil
 }
 
+// UsingTLS returns true if the connection uses transport layer security (TLS).
+func (c *Conn) UsingTLS() bool {
+	return c.usingTLS
+}
+
 // SetHeader sets a header line in the eventual reply.
 // For example, SetHeader("Content-Type", "text/html; charset=utf-8")
 // will result in the header line

src/pkg/websocket/client.go

@@ -8,6 +8,7 @@ import (
 	"bufio"
 	"bytes"
 	"container/vector"
+	"crypto/tls"
 	"fmt"
 	"http"
 	"io"
@@ -22,6 +23,7 @@ type ProtocolError struct {
 }
 
 var (
+	ErrBadScheme            = os.ErrorString("bad scheme")
 	ErrBadStatus            = &ProtocolError{"bad status"}
 	ErrBadUpgrade           = &ProtocolError{"missing or bad upgrade"}
 	ErrBadWebSocketOrigin   = &ProtocolError{"missing or bad WebSocket-Origin"}
@@ -31,6 +33,17 @@ var (
 	secKeyRandomChars       [0x30 - 0x21 + 0x7F - 0x3A]byte
 )
 
+type DialError struct {
+	URL      string
+	Protocol string
+	Origin   string
+	Error    os.Error
+}
+
+func (e *DialError) String() string {
+	return "websocket.Dial " + e.URL + ": " + e.Error.String()
+}
+
 func init() {
 	i := 0
 	for ch := byte(0x21); ch < 0x30; ch++ {
@@ -86,15 +99,35 @@ A trivial example client:
 	}
 */
 func Dial(url, protocol, origin string) (ws *Conn, err os.Error) {
+	var client net.Conn
+
 	parsedUrl, err := http.ParseURL(url)
 	if err != nil {
-		return
+		goto Error
+	}
+
+	switch parsedUrl.Scheme {
+	case "ws":
+		client, err = net.Dial("tcp", "", parsedUrl.Host)
+
+	case "wss":
+		client, err = tls.Dial("tcp", "", parsedUrl.Host)
+
+	default:
+		err = ErrBadScheme
 	}
-	client, err := net.Dial("tcp", "", parsedUrl.Host)
 	if err != nil {
-		return
+		goto Error
 	}
-	return newClient(parsedUrl.RawPath, parsedUrl.Host, origin, url, protocol, client, handshake)
+
+	ws, err = newClient(parsedUrl.RawPath, parsedUrl.Host, origin, url, protocol, client, handshake)
+	if err != nil {
+		goto Error
+	}
+	return
+
+Error:
+	return nil, &DialError{url, protocol, origin, err}
 }
 
 /*

src/pkg/websocket/server.go

@@ -97,7 +97,12 @@ func (f Handler) ServeHTTP(c *http.Conn, req *http.Request) {
 		return
 	}
 
-	location := "ws://" + req.Host + req.URL.RawPath
+	var location string
+	if c.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)
@@ -185,7 +190,13 @@ func (f Draft75Handler) ServeHTTP(c *http.Conn, req *http.Request) {
 		return
 	}
 	defer rwc.Close()
-	location := "ws://" + req.Host + req.URL.RawPath
+
+	var location string
+	if c.UsingTLS() {
+		location = "wss://" + req.Host + req.URL.RawPath
+	} else {
+		location = "ws://" + req.Host + req.URL.RawPath
+	}
 
 	// TODO(ukai): verify origin,location,protocol.