feat: add draft support for trojan

Author: mrhaoxx

tcp/detect.go

@@ -172,3 +172,16 @@ func DetectMinecraft(r io.Reader, _ *Conn) string {
 	}
 	return ""
 }
+
+func DetectTROJAN(r io.Reader, conn *Conn) string {
+	var buf = make([]byte, 58)
+	n, err := r.Read(buf)
+	if err != nil || n != 58 {
+		return ""
+	}
+
+	if reflect.DeepEqual(buf[56:58], []byte("\r\n")) {
+		return "TROJAN"
+	}
+	return ""
+}

trojan/metadata.go

@@ -0,0 +1,126 @@
+package trojan
+
+import (
+	"encoding/binary"
+	"errors"
+	"fmt"
+	"io"
+	"net"
+	"strconv"
+)
+
+type Command byte
+
+type AddressType byte
+
+type Metadata struct {
+	Command
+	*Address
+}
+
+const (
+	IPv4       AddressType = 1
+	DomainName AddressType = 3
+	IPv6       AddressType = 4
+)
+
+type Address struct {
+	DomainName  string
+	Port        int
+	NetworkType string
+	net.IP
+	AddressType
+}
+
+func (r *Metadata) ReadFrom(rr io.Reader) error {
+	byteBuf := [1]byte{}
+	_, err := io.ReadFull(rr, byteBuf[:])
+	if err != nil {
+		return err
+	}
+	r.Command = Command(byteBuf[0])
+	r.Address = new(Address)
+	err = r.Address.ReadFrom(rr)
+	if err != nil {
+		return errors.New("failed to parse address")
+	}
+	return nil
+}
+
+func (a *Address) ReadFrom(r io.Reader) error {
+	byteBuf := [1]byte{}
+	_, err := io.ReadFull(r, byteBuf[:])
+	if err != nil {
+		return fmt.Errorf("unable to read ATYP: %w", err)
+	}
+	a.AddressType = AddressType(byteBuf[0])
+	switch a.AddressType {
+	case IPv4:
+		var buf [6]byte
+		_, err := io.ReadFull(r, buf[:])
+		if err != nil {
+			return fmt.Errorf("failed to read IPv4: %w", err)
+		}
+		a.IP = buf[0:4]
+		a.Port = int(binary.BigEndian.Uint16(buf[4:6]))
+	case IPv6:
+		var buf [18]byte
+		_, err := io.ReadFull(r, buf[:])
+		if err != nil {
+			return fmt.Errorf("failed to read IPv6: %w", err)
+		}
+		a.IP = buf[0:16]
+		a.Port = int(binary.BigEndian.Uint16(buf[16:18]))
+	case DomainName:
+		_, err := io.ReadFull(r, byteBuf[:])
+		length := byteBuf[0]
+		if err != nil {
+			return fmt.Errorf("failed to read domain name length: %w", err)
+		}
+		buf := make([]byte, length+2)
+		_, err = io.ReadFull(r, buf)
+		if err != nil {
+			return fmt.Errorf("failed to read domain name: %w", err)
+		}
+		host := buf[0:length]
+		if ip := net.ParseIP(string(host)); ip != nil {
+			a.IP = ip
+			if ip.To4() != nil {
+				a.AddressType = IPv4
+			} else {
+				a.AddressType = IPv6
+			}
+		} else {
+			a.DomainName = string(host)
+		}
+		a.Port = int(binary.BigEndian.Uint16(buf[length : length+2]))
+	default:
+		return fmt.Errorf("invalid ATYP %s", strconv.FormatInt(int64(a.AddressType), 10))
+	}
+	return nil
+}
+
+func (a *Address) WriteTo(w io.Writer) error {
+	_, err := w.Write([]byte{byte(a.AddressType)})
+	if err != nil {
+		return err
+	}
+	switch a.AddressType {
+	case DomainName:
+		w.Write([]byte{byte(len(a.DomainName))})
+		_, err = w.Write([]byte(a.DomainName))
+	case IPv4:
+		_, err = w.Write(a.IP.To4())
+	case IPv6:
+		_, err = w.Write(a.IP.To16())
+	default:
+		return fmt.Errorf("invalid ATYP %s", strconv.FormatInt(int64(a.AddressType), 10))
+	}
+	if err != nil {
+		return err
+	}
+	port := [2]byte{}
+	binary.BigEndian.PutUint16(port[:], uint16(a.Port))
+	_, err = w.Write(port[:])
+	return err
+}