init: tun support with sing-tun

app/internal/tun/log.go

@@ -0,0 +1,62 @@
+package tun
+
+import (
+	"github.com/sagernet/sing/common/logger"
+	"go.uber.org/zap"
+)
+
+var _ logger.Logger = (*singLogger)(nil)
+
+type singLogger struct {
+	tag       string
+	zapLogger *zap.Logger
+}
+
+func (l *singLogger) Trace(args ...any) {
+	if l.zapLogger == nil {
+		return
+	}
+	l.zapLogger.Debug(l.tag, zap.Any("args", args))
+}
+
+func (l *singLogger) Debug(args ...any) {
+	if l.zapLogger == nil {
+		return
+	}
+	l.zapLogger.Debug(l.tag, zap.Any("args", args))
+}
+
+func (l *singLogger) Info(args ...any) {
+	if l.zapLogger == nil {
+		return
+	}
+	l.zapLogger.Info(l.tag, zap.Any("args", args))
+}
+
+func (l *singLogger) Warn(args ...any) {
+	if l.zapLogger == nil {
+		return
+	}
+	l.zapLogger.Warn(l.tag, zap.Any("args", args))
+}
+
+func (l *singLogger) Error(args ...any) {
+	if l.zapLogger == nil {
+		return
+	}
+	l.zapLogger.Error(l.tag, zap.Any("args", args))
+}
+
+func (l *singLogger) Fatal(args ...any) {
+	if l.zapLogger == nil {
+		return
+	}
+	l.zapLogger.Fatal(l.tag, zap.Any("args", args))
+}
+
+func (l *singLogger) Panic(args ...any) {
+	if l.zapLogger == nil {
+		return
+	}
+	l.zapLogger.Panic(l.tag, zap.Any("args", args))
+}

app/internal/tun/server.go

@@ -0,0 +1,211 @@
+package tun
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"io"
+	"net"
+	"net/netip"
+
+	"github.com/apernet/hysteria/core/client"
+	tun "github.com/sagernet/sing-tun"
+	"github.com/sagernet/sing/common/buf"
+	"github.com/sagernet/sing/common/metadata"
+	"github.com/sagernet/sing/common/network"
+	"go.uber.org/zap"
+)
+
+type Server struct {
+	HyClient    client.Client
+	EventLogger EventLogger
+
+	// for debugging
+	Logger *zap.Logger
+
+	IfName     string
+	MTU        uint32
+	UDPTimeout int64 // in seconds
+
+	// required by system stack
+	Inet4Address []netip.Prefix
+	Inet6Address []netip.Prefix
+
+	tunIf    tun.Tun
+	tunStack tun.Stack
+}
+
+type EventLogger interface {
+	TCPRequest(addr, reqAddr string)
+	TCPError(addr, reqAddr string, err error)
+	UDPRequest(addr string)
+	UDPError(addr string, err error)
+}
+
+func (s *Server) Start() error {
+	tunOpts := tun.Options{
+		Name:         s.IfName,
+		Inet4Address: s.Inet4Address,
+		Inet6Address: s.Inet6Address,
+		MTU:          s.MTU,
+		GSO:          true,
+		Logger: &singLogger{
+			tag:       "tun",
+			zapLogger: s.Logger,
+		},
+	}
+	tunIf, err := tun.New(tunOpts)
+	if err != nil {
+		return fmt.Errorf("failed to create tun interface: %w", err)
+	}
+	s.tunIf = tunIf
+
+	tunStack, err := tun.NewStack("system", tun.StackOptions{
+		Context:    context.Background(),
+		Tun:        tunIf,
+		TunOptions: tunOpts,
+		UDPTimeout: s.UDPTimeout,
+		Handler:    &tunHandler{s},
+		Logger: &singLogger{
+			tag:       "tun-stack",
+			zapLogger: s.Logger,
+		},
+	})
+	if err != nil {
+		return fmt.Errorf("failed to create tun stack: %w", err)
+	}
+	s.tunStack = tunStack
+	err = tunStack.Start()
+	if err != nil {
+		return fmt.Errorf("failed to start tun stack: %w", err)
+	}
+	return nil
+}
+
+func (s *Server) Close() error {
+	var ifErr, stackErr error
+	if s.tunIf != nil {
+		ifErr = s.tunIf.Close()
+	}
+	if s.tunStack != nil {
+		stackErr = s.tunStack.Close()
+	}
+	return errors.Join(ifErr, stackErr)
+}
+
+type tunHandler struct {
+	*Server
+}
+
+var _ tun.Handler = (*tunHandler)(nil)
+
+func (t *tunHandler) NewConnection(ctx context.Context, conn net.Conn, m metadata.Metadata) error {
+	addr := m.Source.String()
+	reqAddr := m.Destination.String()
+	if t.EventLogger != nil {
+		t.EventLogger.TCPRequest(addr, reqAddr)
+	}
+	var closeErr error
+	defer func() {
+		if t.EventLogger != nil {
+			t.EventLogger.TCPError(addr, reqAddr, closeErr)
+		}
+	}()
+	rc, err := t.HyClient.TCP(reqAddr)
+	if err != nil {
+		closeErr = err
+		// the returned err is ignored by caller
+		return nil
+	}
+	defer rc.Close()
+
+	// start forwarding
+	copyErrChan := make(chan error, 3)
+	go func() {
+		<-ctx.Done()
+		copyErrChan <- ctx.Err()
+	}()
+	go func() {
+		_, copyErr := io.Copy(rc, conn)
+		copyErrChan <- copyErr
+	}()
+	go func() {
+		_, copyErr := io.Copy(conn, rc)
+		copyErrChan <- copyErr
+	}()
+	closeErr = <-copyErrChan
+	return nil
+}
+
+func (t *tunHandler) NewPacketConnection(ctx context.Context, conn network.PacketConn, m metadata.Metadata) error {
+	addr := m.Source.String()
+	if t.EventLogger != nil {
+		t.EventLogger.UDPRequest(addr)
+	}
+	var closeErr error
+	defer func() {
+		if t.EventLogger != nil {
+			t.EventLogger.UDPError(addr, closeErr)
+		}
+	}()
+	rc, err := t.HyClient.UDP()
+	if err != nil {
+		closeErr = err
+		// the returned err is simply called into NewError again
+		return nil
+	}
+	defer rc.Close()
+
+	// start forwarding
+	copyErrChan := make(chan error, 3)
+	go func() {
+		<-ctx.Done()
+		copyErrChan <- ctx.Err()
+	}()
+	// local <- remote
+	go func() {
+		for {
+			bs, from, err := rc.Receive()
+			if err != nil {
+				copyErrChan <- err
+				return
+			}
+			var fromAddr metadata.Socksaddr
+			if ap, perr := netip.ParseAddrPort(from); perr == nil {
+				fromAddr = metadata.SocksaddrFromNetIP(ap)
+			} else {
+				fromAddr.Fqdn = from
+			}
+			err = conn.WritePacket(buf.As(bs), fromAddr)
+			if err != nil {
+				copyErrChan <- err
+				return
+			}
+		}
+	}()
+	// local -> remote
+	go func() {
+		buffer := buf.NewPacket()
+		defer buffer.Release()
+
+		for {
+			buffer.Reset()
+			addr, err := conn.ReadPacket(buffer)
+			if err != nil {
+				copyErrChan <- err
+				return
+			}
+			err = rc.Send(buffer.Bytes(), addr.String())
+			if err != nil {
+				copyErrChan <- err
+				return
+			}
+		}
+	}()
+	closeErr = <-copyErrChan
+	return nil
+}
+
+func (t *tunHandler) NewError(ctx context.Context, err error) {
+	// unused
+}