9b660c1959
This makes the various protocol priorities configurable among the other options. With this, it's possible to prefer QUIC over TCP for WAN connections, for example. Both sides need to be similarly configured for this to work properly. The default priority order remains the same as previously (TCP, QUIC, Relay, with LAN better than WAN). To make this happen I made each dialer & listener more priority aware, and moved the check for whether a connection is LAN or not into the dialer / listener -- this is the new "lanChecker" type that's passed around.
242 lines
5.8 KiB
Go
242 lines
5.8 KiB
Go
// Copyright (C) 2016 The Syncthing Authors.
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//
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// This Source Code Form is subject to the terms of the Mozilla Public
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// License, v. 2.0. If a copy of the MPL was not distributed with this file,
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// You can obtain one at https://mozilla.org/MPL/2.0/.
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package connections
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import (
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"context"
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"crypto/tls"
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"net"
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"net/url"
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"sync"
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"time"
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"github.com/syncthing/syncthing/lib/config"
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"github.com/syncthing/syncthing/lib/connections/registry"
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"github.com/syncthing/syncthing/lib/dialer"
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"github.com/syncthing/syncthing/lib/nat"
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"github.com/syncthing/syncthing/lib/svcutil"
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)
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func init() {
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factory := &tcpListenerFactory{}
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for _, scheme := range []string{"tcp", "tcp4", "tcp6"} {
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listeners[scheme] = factory
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}
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}
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type tcpListener struct {
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svcutil.ServiceWithError
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onAddressesChangedNotifier
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uri *url.URL
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cfg config.Wrapper
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tlsCfg *tls.Config
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conns chan internalConn
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factory listenerFactory
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registry *registry.Registry
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lanChecker *lanChecker
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natService *nat.Service
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mapping *nat.Mapping
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laddr net.Addr
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mut sync.RWMutex
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}
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func (t *tcpListener) serve(ctx context.Context) error {
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tcaddr, err := net.ResolveTCPAddr(t.uri.Scheme, t.uri.Host)
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if err != nil {
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l.Infoln("Listen (BEP/tcp):", err)
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return err
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}
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lc := net.ListenConfig{
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Control: dialer.ReusePortControl,
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}
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listener, err := lc.Listen(context.TODO(), t.uri.Scheme, tcaddr.String())
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if err != nil {
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l.Infoln("Listen (BEP/tcp):", err)
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return err
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}
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defer listener.Close()
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// We might bind to :0, so use the port we've been given.
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tcaddr = listener.Addr().(*net.TCPAddr)
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t.notifyAddressesChanged(t)
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defer t.clearAddresses(t)
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t.registry.Register(t.uri.Scheme, tcaddr)
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defer t.registry.Unregister(t.uri.Scheme, tcaddr)
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l.Infof("TCP listener (%v) starting", tcaddr)
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defer l.Infof("TCP listener (%v) shutting down", tcaddr)
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mapping := t.natService.NewMapping(nat.TCP, tcaddr.IP, tcaddr.Port)
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mapping.OnChanged(func() {
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t.notifyAddressesChanged(t)
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})
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// Should be called after t.mapping is nil'ed out.
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defer t.natService.RemoveMapping(mapping)
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t.mut.Lock()
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t.mapping = mapping
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t.laddr = tcaddr
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t.mut.Unlock()
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defer func() {
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t.mut.Lock()
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t.mapping = nil
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t.laddr = nil
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t.mut.Unlock()
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}()
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acceptFailures := 0
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const maxAcceptFailures = 10
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// :(, but what can you do.
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tcpListener := listener.(*net.TCPListener)
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for {
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_ = tcpListener.SetDeadline(time.Now().Add(time.Second))
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conn, err := tcpListener.Accept()
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select {
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case <-ctx.Done():
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if err == nil {
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conn.Close()
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}
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return nil
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default:
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}
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if err != nil {
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if err, ok := err.(*net.OpError); !ok || !err.Timeout() {
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l.Warnln("Listen (BEP/tcp): Accepting connection:", err)
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acceptFailures++
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if acceptFailures > maxAcceptFailures {
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// Return to restart the listener, because something
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// seems permanently damaged.
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return err
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}
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// Slightly increased delay for each failure.
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time.Sleep(time.Duration(acceptFailures) * time.Second)
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}
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continue
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}
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acceptFailures = 0
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l.Debugln("Listen (BEP/tcp): connect from", conn.RemoteAddr())
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if err := dialer.SetTCPOptions(conn); err != nil {
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l.Debugln("Listen (BEP/tcp): setting tcp options:", err)
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}
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if tc := t.cfg.Options().TrafficClass; tc != 0 {
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if err := dialer.SetTrafficClass(conn, tc); err != nil {
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l.Debugln("Listen (BEP/tcp): setting traffic class:", err)
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}
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}
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tc := tls.Server(conn, t.tlsCfg)
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if err := tlsTimedHandshake(tc); err != nil {
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l.Infoln("Listen (BEP/tcp): TLS handshake:", err)
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tc.Close()
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continue
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}
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priority := t.cfg.Options().ConnectionPriorityTCPWAN
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isLocal := t.lanChecker.isLAN(conn.RemoteAddr())
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if isLocal {
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priority = t.cfg.Options().ConnectionPriorityTCPLAN
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}
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t.conns <- newInternalConn(tc, connTypeTCPServer, isLocal, priority)
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}
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}
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func (t *tcpListener) URI() *url.URL {
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return t.uri
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}
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func (t *tcpListener) WANAddresses() []*url.URL {
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t.mut.RLock()
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uris := []*url.URL{
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maybeReplacePort(t.uri, t.laddr),
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}
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if t.mapping != nil {
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addrs := t.mapping.ExternalAddresses()
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for _, addr := range addrs {
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uri := *t.uri
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// Does net.JoinHostPort internally
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uri.Host = addr.String()
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uris = append(uris, &uri)
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// For every address with a specified IP, add one without an IP,
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// just in case the specified IP is still internal (router behind DMZ).
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if len(addr.IP) != 0 && !addr.IP.IsUnspecified() {
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uri = *t.uri
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addr.IP = nil
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uri.Host = addr.String()
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uris = append(uris, &uri)
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}
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}
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}
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t.mut.RUnlock()
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// If we support ReusePort, add an unspecified zero port address, which will be resolved by the discovery server
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// in hopes that TCP punch through works.
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if dialer.SupportsReusePort {
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uri := *t.uri
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uri.Host = "0.0.0.0:0"
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uris = append([]*url.URL{&uri}, uris...)
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}
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return uris
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}
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func (t *tcpListener) LANAddresses() []*url.URL {
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t.mut.RLock()
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uri := maybeReplacePort(t.uri, t.laddr)
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t.mut.RUnlock()
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addrs := []*url.URL{uri}
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addrs = append(addrs, getURLsForAllAdaptersIfUnspecified(uri.Scheme, uri)...)
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return addrs
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}
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func (t *tcpListener) String() string {
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return t.uri.String()
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}
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func (t *tcpListener) Factory() listenerFactory {
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return t.factory
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}
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func (t *tcpListener) NATType() string {
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return "unknown"
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}
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type tcpListenerFactory struct{}
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func (f *tcpListenerFactory) New(uri *url.URL, cfg config.Wrapper, tlsCfg *tls.Config, conns chan internalConn, natService *nat.Service, registry *registry.Registry, lanChecker *lanChecker) genericListener {
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l := &tcpListener{
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uri: fixupPort(uri, config.DefaultTCPPort),
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cfg: cfg,
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tlsCfg: tlsCfg,
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conns: conns,
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natService: natService,
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factory: f,
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registry: registry,
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lanChecker: lanChecker,
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}
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l.ServiceWithError = svcutil.AsService(l.serve, l.String())
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return l
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}
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func (tcpListenerFactory) Valid(_ config.Configuration) error {
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// Always valid
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return nil
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}
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