runtime/internal/lib/websocket/hybrid.go

// Copyright 2015 The Vanadium 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 (
	"net"
	"time"

	"v.io/x/ref/runtime/internal/lib/tcputil"

	"v.io/v23/context"
)

// TODO(jhahn): Figure out a way for this mapping to be shared.
var mapWebSocketToTCP = map[string]string{"ws": "tcp", "ws4": "tcp4", "ws6": "tcp6", "wsh": "tcp", "wsh4": "tcp4", "wsh6": "tcp6", "tcp": "tcp", "tcp4": "tcp4", "tcp6": "tcp6"}

// HybridDial returns net.Conn that can be used with a HybridListener but
// always uses tcp. A client must specifically elect to use websockets by
// calling websocket.Dialer. The returned net.Conn will report 'tcp' as its
// Network.
func HybridDial(ctx *context.T, network, address string, timeout time.Duration) (net.Conn, error) {
	tcp := mapWebSocketToTCP[network]
	conn, err := net.DialTimeout(tcp, address, timeout)
	if err != nil {
		return nil, err
	}
	if err := tcputil.EnableTCPKeepAlive(conn); err != nil {
		return nil, err
	}
	return conn, nil
}

// HybridResolve performs a DNS resolution on the network, address and always
// returns tcp as its Network.
func HybridResolve(ctx *context.T, network, address string) (string, string, error) {
	tcp := mapWebSocketToTCP[network]
	tcpAddr, err := net.ResolveTCPAddr(tcp, address)
	if err != nil {
		return "", "", err
	}
	return tcp, tcpAddr.String(), nil
}

// HybridListener returns a net.Listener that supports both tcp and
// websockets over the same, single, port. A listen address of
// --v23.tcp.protocol=wsh --v23.tcp.address=127.0.0.1:8101 means
// that port 8101 can accept connections that use either tcp or websocket.
// The listener looks at the first 4 bytes of the incoming data stream
// to decide if it's a websocket protocol or not. These must be 'GET ' for
// websockets, all other protocols must guarantee to not send 'GET ' as the
// first four bytes of the payload.
func HybridListener(ctx *context.T, protocol, address string) (net.Listener, error) {
	return listener(protocol, address, true)
}