Add proxy support for ICMP echo request

transport/wireguard/device_nat.go

@@ -0,0 +1,103 @@
+package wireguard
+
+import (
+	"context"
+	"sync/atomic"
+	"time"
+
+	"github.com/sagernet/sing-box/adapter"
+	"github.com/sagernet/sing-box/log"
+	"github.com/sagernet/sing-tun"
+	"github.com/sagernet/sing-tun/ping"
+	"github.com/sagernet/sing/common/buf"
+	"github.com/sagernet/sing/common/logger"
+)
+
+var _ Device = (*natDeviceWrapper)(nil)
+
+type natDeviceWrapper struct {
+	Device
+	ctx            context.Context
+	logger         logger.ContextLogger
+	packetOutbound chan *buf.Buffer
+	rewriter       *ping.Rewriter
+	buffer         [][]byte
+}
+
+func NewNATDevice(ctx context.Context, logger logger.ContextLogger, upstream Device) NatDevice {
+	wrapper := &natDeviceWrapper{
+		Device:         upstream,
+		ctx:            ctx,
+		logger:         logger,
+		packetOutbound: make(chan *buf.Buffer, 256),
+		rewriter:       ping.NewRewriter(ctx, logger, upstream.Inet4Address(), upstream.Inet6Address()),
+	}
+	return wrapper
+}
+
+func (d *natDeviceWrapper) Read(bufs [][]byte, sizes []int, offset int) (n int, err error) {
+	select {
+	case packet := <-d.packetOutbound:
+		defer packet.Release()
+		sizes[0] = copy(bufs[0][offset:], packet.Bytes())
+		return 1, nil
+	default:
+	}
+	return d.Device.Read(bufs, sizes, offset)
+}
+
+func (d *natDeviceWrapper) Write(bufs [][]byte, offset int) (int, error) {
+	for _, buffer := range bufs {
+		handled, err := d.rewriter.WriteBack(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, timeout time.Duration) (tun.DirectRouteDestination, error) {
+	ctx := log.ContextWithNewID(d.ctx)
+	session := tun.DirectRouteSession{
+		Source:      metadata.Source.Addr,
+		Destination: metadata.Destination.Addr,
+	}
+	d.rewriter.CreateSession(session, routeContext)
+	d.logger.InfoContext(ctx, "linked ", metadata.Network, " connection from ", metadata.Source.AddrString(), " to ", metadata.Destination.AddrString())
+	return &natDestination{device: d, session: session}, nil
+}
+
+var _ tun.DirectRouteDestination = (*natDestination)(nil)
+
+type natDestination struct {
+	device  *natDeviceWrapper
+	session tun.DirectRouteSession
+	closed  atomic.Bool
+}
+
+func (d *natDestination) WritePacket(buffer *buf.Buffer) error {
+	d.device.rewriter.RewritePacket(buffer.Bytes())
+	d.device.packetOutbound <- buffer
+	return nil
+}
+
+func (d *natDestination) Close() error {
+	d.closed.Store(true)
+	d.device.rewriter.DeleteSession(d.session)
+	return nil
+}
+
+func (d *natDestination) IsClosed() bool {
+	return d.closed.Load()
+}