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tcp_listen.go
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tcp_listen.go
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// Copyright (C) 2016 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 https://mozilla.org/MPL/2.0/.
package connections
import (
"crypto/tls"
"net"
"net/url"
"sync"
"time"
"github.com/syncthing/syncthing/lib/config"
"github.com/syncthing/syncthing/lib/dialer"
"github.com/syncthing/syncthing/lib/nat"
)
func init() {
factory := &tcpListenerFactory{}
for _, scheme := range []string{"tcp", "tcp4", "tcp6"} {
listeners[scheme] = factory
}
}
type tcpListener struct {
onAddressesChangedNotifier
uri *url.URL
cfg *config.Wrapper
tlsCfg *tls.Config
stop chan struct{}
conns chan internalConn
factory listenerFactory
natService *nat.Service
mapping *nat.Mapping
err error
mut sync.RWMutex
}
func (t *tcpListener) Serve() {
t.mut.Lock()
t.err = nil
t.mut.Unlock()
tcaddr, err := net.ResolveTCPAddr(t.uri.Scheme, t.uri.Host)
if err != nil {
t.mut.Lock()
t.err = err
t.mut.Unlock()
l.Infoln("listen (BEP/tcp):", err)
return
}
listener, err := net.ListenTCP(t.uri.Scheme, tcaddr)
if err != nil {
t.mut.Lock()
t.err = err
t.mut.Unlock()
l.Infoln("listen (BEP/tcp):", err)
return
}
defer listener.Close()
l.Infof("TCP listener (%v) starting", listener.Addr())
defer l.Infof("TCP listener (%v) shutting down", listener.Addr())
mapping := t.natService.NewMapping(nat.TCP, tcaddr.IP, tcaddr.Port)
mapping.OnChanged(func(_ *nat.Mapping, _, _ []nat.Address) {
t.notifyAddressesChanged(t)
})
defer t.natService.RemoveMapping(mapping)
t.mut.Lock()
t.mapping = mapping
t.mut.Unlock()
for {
listener.SetDeadline(time.Now().Add(time.Second))
conn, err := listener.Accept()
select {
case <-t.stop:
if err == nil {
conn.Close()
}
t.mut.Lock()
t.mapping = nil
t.mut.Unlock()
return
default:
}
if err != nil {
if err, ok := err.(*net.OpError); !ok || !err.Timeout() {
l.Warnln("Accepting connection (BEP/tcp):", err)
}
continue
}
l.Debugln("connect from", conn.RemoteAddr())
err = dialer.SetTCPOptions(conn)
if err != nil {
l.Infoln(err)
}
err = dialer.SetTrafficClass(conn, t.cfg.Options().TrafficClass)
if err != nil {
l.Debugf("failed to set traffic class: %s", err)
}
tc := tls.Server(conn, t.tlsCfg)
err = tlsTimedHandshake(tc)
if err != nil {
l.Infoln("TLS handshake (BEP/tcp):", err)
tc.Close()
continue
}
t.conns <- internalConn{tc, connTypeTCPServer, tcpPriority}
}
}
func (t *tcpListener) Stop() {
close(t.stop)
}
func (t *tcpListener) URI() *url.URL {
return t.uri
}
func (t *tcpListener) WANAddresses() []*url.URL {
uris := t.LANAddresses()
t.mut.RLock()
if t.mapping != nil {
addrs := t.mapping.ExternalAddresses()
for _, addr := range addrs {
uri := *t.uri
// Does net.JoinHostPort internally
uri.Host = addr.String()
uris = append(uris, &uri)
// For every address with a specified IP, add one without an IP,
// just in case the specified IP is still internal (router behind DMZ).
if len(addr.IP) != 0 && !addr.IP.IsUnspecified() {
uri = *t.uri
addr.IP = nil
uri.Host = addr.String()
uris = append(uris, &uri)
}
}
}
t.mut.RUnlock()
return uris
}
func (t *tcpListener) LANAddresses() []*url.URL {
return []*url.URL{t.uri}
}
func (t *tcpListener) Error() error {
t.mut.RLock()
err := t.err
t.mut.RUnlock()
return err
}
func (t *tcpListener) String() string {
return t.uri.String()
}
func (t *tcpListener) Factory() listenerFactory {
return t.factory
}
type tcpListenerFactory struct{}
func (f *tcpListenerFactory) New(uri *url.URL, cfg *config.Wrapper, tlsCfg *tls.Config, conns chan internalConn, natService *nat.Service) genericListener {
return &tcpListener{
uri: fixupPort(uri, config.DefaultTCPPort),
cfg: cfg,
tlsCfg: tlsCfg,
conns: conns,
natService: natService,
stop: make(chan struct{}),
factory: f,
}
}
func (tcpListenerFactory) Enabled(cfg config.Configuration) bool {
return true
}