lib/connections: Support setting traffic class (fixes #3790)

lib/config/optionsconfiguration.go

@@ -41,6 +41,7 @@ type OptionsConfiguration struct {
 	OverwriteRemoteDevNames bool     `xml:"overwriteRemoteDeviceNamesOnConnect" json:"overwriteRemoteDeviceNamesOnConnect" default:"false"`
 	TempIndexMinBlocks      int      `xml:"tempIndexMinBlocks" json:"tempIndexMinBlocks" default:"10"`
 	UnackedNotificationIDs  []string `xml:"unackedNotificationID" json:"unackedNotificationIDs"`
+	TrafficClass            int      `xml:"trafficClass" json:"trafficClass"`
 
 	DeprecatedUPnPEnabled  bool     `xml:"upnpEnabled,omitempty" json:"-"`
 	DeprecatedUPnPLeaseM   int      `xml:"upnpLeaseMinutes,omitempty" json:"-"`

lib/connections/relay_dial.go

@@ -45,6 +45,11 @@ func (d *relayDialer) Dial(id protocol.DeviceID, uri *url.URL) (internalConn, er
 		return internalConn{}, err
 	}
 
+	err = dialer.SetTrafficClass(conn, d.cfg.Options().TrafficClass)
+	if err != nil {
+		l.Debugf("failed to set traffic class: %s", err)
+	}
+
 	var tc *tls.Conn
 	if inv.ServerSocket {
 		tc = tls.Server(conn, d.tlsCfg)

lib/connections/relay_listen.go

@@ -29,6 +29,7 @@ type relayListener struct {
 	onAddressesChangedNotifier
 
 	uri     *url.URL
+	cfg     *config.Wrapper
 	tlsCfg  *tls.Config
 	conns   chan internalConn
 	factory listenerFactory
@@ -79,6 +80,11 @@ func (t *relayListener) Serve() {
 				l.Infoln(err)
 			}
 
+			err = dialer.SetTrafficClass(conn, t.cfg.Options().TrafficClass)
+			if err != nil {
+				l.Debugf("failed to set traffic class: %s", err)
+			}
+
 			var tc *tls.Conn
 			if inv.ServerSocket {
 				tc = tls.Server(conn, t.tlsCfg)
@@ -170,6 +176,7 @@ type relayListenerFactory struct{}
 func (f *relayListenerFactory) New(uri *url.URL, cfg *config.Wrapper, tlsCfg *tls.Config, conns chan internalConn, natService *nat.Service) genericListener {
 	return &relayListener{
 		uri:     uri,
+		cfg:     cfg,
 		tlsCfg:  tlsCfg,
 		conns:   conns,
 		factory: f,

lib/connections/tcp_dial.go

@@ -39,6 +39,16 @@ func (d *tcpDialer) Dial(id protocol.DeviceID, uri *url.URL) (internalConn, erro
 		return internalConn{}, err
 	}
 
+	err = dialer.SetTCPOptions(conn)
+	if err != nil {
+		l.Infoln(err)
+	}
+
+	err = dialer.SetTrafficClass(conn, d.cfg.Options().TrafficClass)
+	if err != nil {
+		l.Debugf("failed to set traffic class: %s", err)
+	}
+
 	tc := tls.Client(conn, d.tlsCfg)
 	err = tlsTimedHandshake(tc)
 	if err != nil {

lib/connections/tcp_listen.go

@@ -30,6 +30,7 @@ type tcpListener struct {
 	onAddressesChangedNotifier
 
 	uri     *url.URL
+	cfg     *config.Wrapper
 	tlsCfg  *tls.Config
 	stop    chan struct{}
 	conns   chan internalConn
@@ -107,6 +108,11 @@ func (t *tcpListener) Serve() {
 			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 {
@@ -176,6 +182,7 @@ 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),
+		cfg:        cfg,
 		tlsCfg:     tlsCfg,
 		conns:      conns,
 		natService: natService,

lib/dialer/public.go

@@ -10,6 +10,9 @@ import (
 	"fmt"
 	"net"
 	"time"
+
+	"golang.org/x/net/ipv4"
+	"golang.org/x/net/ipv6"
 )
 
 // Dial tries dialing via proxy if a proxy is configured, and falls back to
@@ -75,3 +78,22 @@ func SetTCPOptions(conn net.Conn) error {
 		return fmt.Errorf("unknown connection type %T", conn)
 	}
 }
+
+func SetTrafficClass(conn net.Conn, class int) error {
+	switch conn := conn.(type) {
+	case *net.TCPConn:
+		e1 := ipv4.NewConn(conn).SetTOS(class)
+		e2 := ipv6.NewConn(conn).SetTrafficClass(class)
+
+		if e1 != nil {
+			return e1
+		}
+		return e2
+
+	case dialerConn:
+		return SetTrafficClass(conn.Conn, class)
+
+	default:
+		return fmt.Errorf("unknown connection type %T", conn)
+	}
+}