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// Copyright (C) 2019 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/.
// +build go1.12
package connections
import (
"context"
"crypto/tls"
"net"
"net/url"
"strings"
"sync"
"sync/atomic"
"time"
"github.com/lucas-clemente/quic-go"
"github.com/syncthing/syncthing/lib/config"
"github.com/syncthing/syncthing/lib/connections/registry"
"github.com/syncthing/syncthing/lib/nat"
"github.com/syncthing/syncthing/lib/stun"
"github.com/syncthing/syncthing/lib/util"
)
func init() {
factory := &quicListenerFactory{}
for _, scheme := range []string{"quic", "quic4", "quic6"} {
listeners[scheme] = factory
}
}
type quicListener struct {
util.ServiceWithError
nat atomic.Value
onAddressesChangedNotifier
uri *url.URL
cfg config.Wrapper
tlsCfg *tls.Config
conns chan internalConn
factory listenerFactory
address *url.URL
mut sync.Mutex
}
func (t *quicListener) OnNATTypeChanged(natType stun.NATType) {
if natType != stun.NATUnknown {
l.Infof("%s detected NAT type: %s", t.uri, natType)
}
t.nat.Store(natType)
}
func (t *quicListener) OnExternalAddressChanged(address *stun.Host, via string) {
var uri *url.URL
if address != nil {
copy := *t.uri
uri = ©
uri.Host = address.TransportAddr()
}
t.mut.Lock()
existingAddress := t.address
t.address = uri
t.mut.Unlock()
if uri != nil && (existingAddress == nil || existingAddress.String() != uri.String()) {
l.Infof("%s resolved external address %s (via %s)", t.uri, uri.String(), via)
t.notifyAddressesChanged(t)
} else if uri == nil && existingAddress != nil {
t.notifyAddressesChanged(t)
}
}
func (t *quicListener) serve(ctx context.Context) error {
network := strings.Replace(t.uri.Scheme, "quic", "udp", -1)
packetConn, err := net.ListenPacket(network, t.uri.Host)
if err != nil {
l.Infoln("Listen (BEP/quic):", err)
return err
}
defer func() { _ = packetConn.Close() }()
svc, conn := stun.New(t.cfg, t, packetConn)
defer func() { _ = conn.Close() }()
go svc.Serve()
defer svc.Stop()
registry.Register(t.uri.Scheme, conn)
defer registry.Unregister(t.uri.Scheme, conn)
listener, err := quic.Listen(conn, t.tlsCfg, quicConfig)
if err != nil {
l.Infoln("Listen (BEP/quic):", err)
return err
}
defer listener.Close()
l.Infof("QUIC listener (%v) starting", packetConn.LocalAddr())
defer l.Infof("QUIC listener (%v) shutting down", packetConn.LocalAddr())
acceptFailures := 0
const maxAcceptFailures = 10
for {
select {
case <-ctx.Done():
return nil
default:
}
session, err := listener.Accept(ctx)
if err == context.Canceled {
return nil
} else if err != nil {
l.Infoln("Listen (BEP/quic): Accepting connection:", err)
acceptFailures++
if acceptFailures > maxAcceptFailures {
// Return to restart the listener, because something
// seems permanently damaged.
return err
}
// Slightly increased delay for each failure.
time.Sleep(time.Duration(acceptFailures) * time.Second)
continue
}
acceptFailures = 0
l.Debugln("connect from", session.RemoteAddr())
streamCtx, cancel := context.WithTimeout(ctx, quicOperationTimeout)
stream, err := session.AcceptStream(streamCtx)
cancel()
if err != nil {
l.Debugf("failed to accept stream from %s: %v", session.RemoteAddr(), err)
_ = session.CloseWithError(1, err.Error())
continue
}
t.conns <- internalConn{&quicTlsConn{session, stream, nil}, connTypeQUICServer, quicPriority}
}
}
func (t *quicListener) URI() *url.URL {
return t.uri
}
func (t *quicListener) WANAddresses() []*url.URL {
uris := t.LANAddresses()
t.mut.Lock()
if t.address != nil {
uris = append(uris, t.address)
}
t.mut.Unlock()
return uris
}
func (t *quicListener) LANAddresses() []*url.URL {
return []*url.URL{t.uri}
}
func (t *quicListener) String() string {
return t.uri.String()
}
func (t *quicListener) Factory() listenerFactory {
return t.factory
}
func (t *quicListener) NATType() string {
v := t.nat.Load().(stun.NATType)
if v == stun.NATUnknown || v == stun.NATError {
return "unknown"
}
return v.String()
}
type quicListenerFactory struct{}
func (f *quicListenerFactory) Valid(config.Configuration) error {
return nil
}
func (f *quicListenerFactory) New(uri *url.URL, cfg config.Wrapper, tlsCfg *tls.Config, conns chan internalConn, natService *nat.Service) genericListener {
l := &quicListener{
uri: fixupPort(uri, config.DefaultQUICPort),
cfg: cfg,
tlsCfg: tlsCfg,
conns: conns,
factory: f,
}
l.ServiceWithError = util.AsServiceWithError(l.serve, l.String())
l.nat.Store(stun.NATUnknown)
return l
}
func (quicListenerFactory) Enabled(cfg config.Configuration) bool {
return true
}
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