Add ping support for WireGuard endpoint

transport/wireguard/device_nat.go

@@ -0,0 +1,85 @@
+package wireguard
+
+import (
+	"github.com/sagernet/sing-box/adapter"
+	"github.com/sagernet/sing-tun"
+	"github.com/sagernet/sing/common/buf"
+)
+
+var _ Device = (*natDeviceWrapper)(nil)
+
+type natDeviceWrapper struct {
+	Device
+	gVisorOutbound
+	packetOutbound chan *buf.Buffer
+	mapping        *tun.NatMapping
+	writer         *tun.NatWriter
+	buffer         [][]byte
+}
+
+func NewNATDevice(upstream Device, ipRewrite bool) NatDevice {
+	wrapper := &natDeviceWrapper{
+		Device:         upstream,
+		gVisorOutbound: newGVisorOutbound(),
+		packetOutbound: make(chan *buf.Buffer, 256),
+		mapping:        tun.NewNatMapping(ipRewrite),
+	}
+	if ipRewrite {
+		wrapper.writer = tun.NewNatWriter(upstream.Inet4Address(), upstream.Inet6Address())
+	}
+	return wrapper
+}
+
+func (d *natDeviceWrapper) Write(bufs [][]byte, offset int) (int, error) {
+	for _, buffer := range bufs {
+		handled, err := d.mapping.WritePacket(buffer[offset:])
+		if handled {
+			if err != nil {
+				return 0, err
+			}
+		} else {
+			d.buffer = append(d.buffer, buffer)
+		}
+	}
+	if len(d.buffer) > 0 {
+		_, err := d.Device.Write(d.buffer, offset)
+		if err != nil {
+			return 0, err
+		}
+		d.buffer = d.buffer[:0]
+	}
+	return 0, nil
+}
+
+func (d *natDeviceWrapper) CreateDestination(metadata adapter.InboundContext, routeContext tun.DirectRouteContext) (tun.DirectRouteDestination, error) {
+	session := tun.DirectRouteSession{
+		Source:      metadata.Source.Addr,
+		Destination: metadata.Destination.Addr,
+	}
+	d.mapping.CreateSession(session, routeContext)
+	return &natDestinationWrapper{d, session}, nil
+}
+
+var _ tun.DirectRouteDestination = (*natDestinationWrapper)(nil)
+
+type natDestinationWrapper struct {
+	device  *natDeviceWrapper
+	session tun.DirectRouteSession
+}
+
+func (d *natDestinationWrapper) WritePacket(buffer *buf.Buffer) error {
+	if d.device.writer != nil {
+		d.device.writer.RewritePacket(buffer.Bytes())
+	}
+	d.device.packetOutbound <- buffer
+	return nil
+}
+
+func (d *natDestinationWrapper) Close() error {
+	d.device.mapping.DeleteSession(d.session)
+	return nil
+}
+
+func (d *natDestinationWrapper) Timeout() bool {
+	return false
+}