Add RDP sniffer

common/sniff/rdp.go

@@ -0,0 +1,90 @@
+package sniff
+
+import (
+	"context"
+	"encoding/binary"
+	"io"
+	"os"
+
+	"github.com/sagernet/sing-box/adapter"
+	C "github.com/sagernet/sing-box/constant"
+	"github.com/sagernet/sing/common/rw"
+)
+
+func RDP(_ context.Context, metadata *adapter.InboundContext, reader io.Reader) error {
+	var tpktVersion uint8
+	err := binary.Read(reader, binary.BigEndian, &tpktVersion)
+	if err != nil {
+		return err
+	}
+	if tpktVersion != 0x03 {
+		return os.ErrInvalid
+	}
+
+	var tpktReserved uint8
+	err = binary.Read(reader, binary.BigEndian, &tpktReserved)
+	if err != nil {
+		return err
+	}
+	if tpktReserved != 0x00 {
+		return os.ErrInvalid
+	}
+
+	var tpktLength uint16
+	err = binary.Read(reader, binary.BigEndian, &tpktLength)
+	if err != nil {
+		return err
+	}
+
+	if tpktLength != 19 {
+		return os.ErrInvalid
+	}
+
+	var cotpLength uint8
+	err = binary.Read(reader, binary.BigEndian, &cotpLength)
+	if err != nil {
+		return err
+	}
+
+	if cotpLength != 14 {
+		return os.ErrInvalid
+	}
+
+	var cotpTpduType uint8
+	err = binary.Read(reader, binary.BigEndian, &cotpTpduType)
+	if err != nil {
+		return err
+	}
+	if cotpTpduType != 0xE0 {
+		return os.ErrInvalid
+	}
+
+	err = rw.SkipN(reader, 5)
+	if err != nil {
+		return err
+	}
+
+	var rdpType uint8
+	err = binary.Read(reader, binary.BigEndian, &rdpType)
+	if err != nil {
+		return err
+	}
+	if rdpType != 0x01 {
+		return os.ErrInvalid
+	}
+	var rdpFlags uint8
+	err = binary.Read(reader, binary.BigEndian, &rdpFlags)
+	if err != nil {
+		return err
+	}
+	var rdpLength uint8
+	err = binary.Read(reader, binary.BigEndian, &rdpLength)
+	if err != nil {
+		return err
+	}
+	if rdpLength != 8 {
+		return os.ErrInvalid
+	}
+	metadata.Protocol = C.ProtocolRDP
+	return nil
+}

common/sniff/rdp_test.go

@@ -0,0 +1,25 @@
+package sniff_test
+
+import (
+	"bytes"
+	"context"
+	"encoding/hex"
+	"testing"
+
+	"github.com/sagernet/sing-box/adapter"
+	"github.com/sagernet/sing-box/common/sniff"
+	C "github.com/sagernet/sing-box/constant"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestSniffRDP(t *testing.T) {
+	t.Parallel()
+
+	pkt, err := hex.DecodeString("030000130ee00000000000010008000b000000010008000b000000")
+	require.NoError(t, err)
+	var metadata adapter.InboundContext
+	err = sniff.RDP(context.TODO(), &metadata, bytes.NewReader(pkt))
+	require.NoError(t, err)
+	require.Equal(t, C.ProtocolRDP, metadata.Protocol)
+}