syncthing/lib/connections/connections_tcp.go

// Copyright (C) 2015 The Syncthing Authors.
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this file,
// You can obtain one at http://mozilla.org/MPL/2.0/.

package connections

import (
	"crypto/tls"
	"net"
	"net/url"
	"strings"

	"github.com/syncthing/syncthing/lib/dialer"
	"github.com/syncthing/syncthing/lib/model"
)

func init() {
	for _, network := range []string{"tcp", "tcp4", "tcp6"} {
		dialers[network] = makeTCPDialer(network)
		listeners[network] = makeTCPListener(network)
	}

}

func makeTCPDialer(network string) DialerFactory {
	return func(uri *url.URL, tlsCfg *tls.Config) (*tls.Conn, error) {
		// Check that there is a port number in uri.Host, otherwise add one.
		host, port, err := net.SplitHostPort(uri.Host)
		if err != nil && strings.HasPrefix(err.Error(), "missing port") {
			// addr is on the form "1.2.3.4"
			uri.Host = net.JoinHostPort(uri.Host, "22000")
		} else if err == nil && port == "" {
			// addr is on the form "1.2.3.4:"
			uri.Host = net.JoinHostPort(host, "22000")
		}

		// Don't try to resolve the address before dialing. The dialer may be a
		// proxy, and we should let the proxy do the resolving in that case.
		conn, err := dialer.Dial(network, uri.Host)
		if err != nil {
			l.Debugln(err)
			return nil, err
		}

		tc := tls.Client(conn, tlsCfg)
		err = tc.Handshake()
		if err != nil {
			tc.Close()
			return nil, err
		}

		return tc, nil
	}
}

func makeTCPListener(network string) ListenerFactory {
	return func(uri *url.URL, tlsCfg *tls.Config, conns chan<- model.IntermediateConnection) {
		tcaddr, err := net.ResolveTCPAddr(network, uri.Host)
		if err != nil {
			l.Fatalln("listen (BEP/tcp):", err)
			return
		}
		listener, err := net.ListenTCP(network, tcaddr)
		if err != nil {
			l.Fatalln("listen (BEP/tcp):", err)
			return
		}

		for {
			conn, err := listener.Accept()
			if err != nil {
				l.Warnln("Accepting connection (BEP/tcp):", err)
				continue
			}

			l.Debugln("connect from", conn.RemoteAddr())

			err = dialer.SetTCPOptions(conn.(*net.TCPConn))
			if err != nil {
				l.Infoln(err)
			}

			tc := tls.Server(conn, tlsCfg)
			err = tc.Handshake()
			if err != nil {
				l.Infoln("TLS handshake (BEP/tcp):", err)
				tc.Close()
				continue
			}

			conns <- model.IntermediateConnection{
				tc, model.ConnectionTypeDirectAccept,
			}
		}
	}
}