http: fix TLS handshake blocking server accept loop

Fixes #2263

R=golang-dev, adg
CC=golang-dev
https://golang.org/cl/5076042

src/pkg/http/serve_test.go

@@ -545,6 +545,19 @@ func TestTLSServer(t *testing.T) {
 		}
 	}))
 	defer ts.Close()
+
+	// Connect an idle TCP connection to this server before we run
+	// our real tests.  This idle connection used to block forever
+	// in the TLS handshake, preventing future connections from
+	// being accepted. It may prevent future accidental blocking
+	// in newConn.
+	idleConn, err := net.Dial("tcp", ts.Listener.Addr().String())
+	if err != nil {
+		t.Fatalf("Dial: %v", err)
+	}
+	defer idleConn.Close()
+	time.AfterFunc(10e9, func() { t.Fatalf("Timeout") })
+
 	if !strings.HasPrefix(ts.URL, "https://") {
 		t.Fatalf("expected test TLS server to start with https://, got %q", ts.URL)
 	}

src/pkg/http/server.go

@@ -178,13 +178,6 @@ func (srv *Server) newConn(rwc net.Conn) (c *conn, err os.Error) {
 	br := bufio.NewReader(c.lr)
 	bw := bufio.NewWriter(rwc)
 	c.buf = bufio.NewReadWriter(br, bw)
-
-	if tlsConn, ok := rwc.(*tls.Conn); ok {
-		tlsConn.Handshake()
-		c.tlsState = new(tls.ConnectionState)
-		*c.tlsState = tlsConn.ConnectionState()
-	}
-
 	return c, nil
 }
 
@@ -562,6 +555,12 @@ func (c *conn) serve() {
 		log.Print(buf.String())
 	}()
 
+	if tlsConn, ok := c.rwc.(*tls.Conn); ok {
+		tlsConn.Handshake()
+		c.tlsState = new(tls.ConnectionState)
+		*c.tlsState = tlsConn.ConnectionState()
+	}
+
 	for {
 		w, err := c.readRequest()
 		if err != nil {