Add tun inbound for linux

inbound/builder.go

@@ -34,6 +34,8 @@ func New(ctx context.Context, router adapter.Router, logger log.Logger, index in
 		return NewMixed(ctx, router, inboundLogger, options.Tag, options.MixedOptions), nil
 	case C.TypeShadowsocks:
 		return NewShadowsocks(ctx, router, inboundLogger, options.Tag, options.ShadowsocksOptions)
+	case C.TypeTun:
+		return NewTun(ctx, router, inboundLogger, options.Tag, options.TunOptions)
 	default:
 		return nil, E.New("unknown inbound type: ", options.Type)
 	}

inbound/default.go

@@ -231,12 +231,16 @@ func (a *myInboundAdapter) newError(err error) {
 }
 
 func (a *myInboundAdapter) NewError(ctx context.Context, err error) {
+	NewError(a.logger, ctx, err)
+}
+
+func NewError(logger log.Logger, ctx context.Context, err error) {
 	common.Close(err)
 	if E.IsClosed(err) {
-		a.logger.WithContext(ctx).Debug("connection closed")
+		logger.WithContext(ctx).Debug("connection closed")
 		return
 	}
-	a.logger.WithContext(ctx).Error(err)
+	logger.WithContext(ctx).Error(err)
 }
 
 func (a *myInboundAdapter) writePacket(buffer *buf.Buffer, destination M.Socksaddr) error {

inbound/tun.go

@@ -0,0 +1,142 @@
+//go:build !no_tun
+
+package inbound
+
+import (
+	"context"
+	"net"
+	"net/netip"
+	"os"
+	"runtime"
+	"strconv"
+	"strings"
+
+	"github.com/sagernet/sing-box/adapter"
+	"github.com/sagernet/sing-box/common/tun"
+	C "github.com/sagernet/sing-box/constant"
+	"github.com/sagernet/sing-box/log"
+	"github.com/sagernet/sing-box/option"
+	E "github.com/sagernet/sing/common/exceptions"
+	F "github.com/sagernet/sing/common/format"
+	M "github.com/sagernet/sing/common/metadata"
+	N "github.com/sagernet/sing/common/network"
+)
+
+var _ adapter.Inbound = (*Tun)(nil)
+
+type Tun struct {
+	tag string
+
+	ctx     context.Context
+	router  adapter.Router
+	logger  log.Logger
+	options option.TunInboundOptions
+
+	tunFd uintptr
+	tun   *tun.GVisorTun
+}
+
+func NewTun(ctx context.Context, router adapter.Router, logger log.Logger, tag string, options option.TunInboundOptions) (*Tun, error) {
+	return &Tun{
+		tag:     tag,
+		ctx:     ctx,
+		router:  router,
+		logger:  logger,
+		options: options,
+	}, nil
+}
+
+func (t *Tun) Type() string {
+	return C.TypeTun
+}
+
+func (t *Tun) Tag() string {
+	return t.tag
+}
+
+func (t *Tun) Start() error {
+	tunName := t.options.InterfaceName
+	if tunName == "" {
+		tunName = mkInterfaceName()
+	}
+	var mtu uint32
+	if t.options.MTU != 0 {
+		mtu = t.options.MTU
+	} else {
+		mtu = 1500
+	}
+
+	tunFd, err := tun.Open(tunName)
+	if err != nil {
+		return E.Cause(err, "create tun interface")
+	}
+	err = tun.Configure(tunName, netip.Prefix(t.options.Inet4Address), netip.Prefix(t.options.Inet6Address), mtu)
+	if err != nil {
+		return E.Cause(err, "configure tun interface")
+	}
+	t.tunFd = tunFd
+	t.tun = tun.NewGVisor(t.ctx, tunFd, mtu, t)
+	err = t.tun.Start()
+	if err != nil {
+		return err
+	}
+	t.logger.Info("started at ", tunName)
+	return nil
+}
+
+func (t *Tun) Close() error {
+	return E.Errors(
+		t.tun.Close(),
+		os.NewFile(t.tunFd, "tun").Close(),
+	)
+}
+
+func (t *Tun) NewConnection(ctx context.Context, conn net.Conn, upstreamMetadata M.Metadata) error {
+	t.logger.WithContext(ctx).Info("inbound connection from ", upstreamMetadata.Source)
+	t.logger.WithContext(ctx).Info("inbound connection to ", upstreamMetadata.Destination)
+	var metadata adapter.InboundContext
+	metadata.Inbound = t.tag
+	metadata.Network = C.NetworkTCP
+	metadata.Source = upstreamMetadata.Source
+	metadata.Destination = upstreamMetadata.Destination
+	return t.router.RouteConnection(ctx, conn, metadata)
+}
+
+func (t *Tun) NewPacketConnection(ctx context.Context, conn N.PacketConn, upstreamMetadata M.Metadata) error {
+	t.logger.WithContext(ctx).Info("inbound packet connection from ", upstreamMetadata.Source)
+	t.logger.WithContext(ctx).Info("inbound packet connection to ", upstreamMetadata.Destination)
+	var metadata adapter.InboundContext
+	metadata.Inbound = t.tag
+	metadata.Network = C.NetworkUDP
+	metadata.Source = upstreamMetadata.Source
+	metadata.Destination = upstreamMetadata.Destination
+	return t.router.RoutePacketConnection(ctx, conn, metadata)
+}
+
+func (t *Tun) NewError(ctx context.Context, err error) {
+	NewError(t.logger, ctx, err)
+}
+
+func mkInterfaceName() (tunName string) {
+	switch runtime.GOOS {
+	case "darwin":
+		tunName = "utun"
+	default:
+		tunName = "tun"
+	}
+	interfaces, err := net.Interfaces()
+	if err != nil {
+		return
+	}
+	var tunIndex int
+	for _, netInterface := range interfaces {
+		if strings.HasPrefix(netInterface.Name, tunName) {
+			index, parseErr := strconv.ParseInt(netInterface.Name[len(tunName):], 10, 16)
+			if parseErr == nil {
+				tunIndex = int(index) + 1
+			}
+		}
+	}
+	tunName = F.ToString(tunName, tunIndex)
+	return
+}

inbound/tun_disabled.go

@@ -0,0 +1,16 @@
+//go:build no_tun
+
+package inbound
+
+import (
+	"context"
+
+	"github.com/sagernet/sing-box/adapter"
+	"github.com/sagernet/sing-box/log"
+	"github.com/sagernet/sing-box/option"
+	E "github.com/sagernet/sing/common/exceptions"
+)
+
+func NewTun(ctx context.Context, router adapter.Router, logger log.Logger, tag string, options option.TunInboundOptions) (adapter.Inbound, error) {
+	return nil, E.New("tun disabled in this build")
+}