chore: better handwritten addons parsing

Author: wwqgtxx

transport/vless/addons.go

@@ -11,35 +11,48 @@ func ReadAddons(data []byte) (*Addons, error) {
 	reader := bytes.NewReader(data)
 	var addons Addons
 	for reader.Len() > 0 {
-		protoHeader, err := reader.ReadByte()
+		tag, err := binary.ReadUvarint(reader)
 		if err != nil {
 			return nil, err
 		}
-		switch protoHeader {
-		case (1 << 3) | 2:
-			flowLen, err := binary.ReadUvarint(reader)
+		number, typ := int32(tag>>3), int8(tag&7)
+		switch typ {
+		case 0: // VARINT
+			_, err = binary.ReadUvarint(reader)
 			if err != nil {
 				return nil, err
 			}
-			flowBytes := make([]byte, flowLen)
-			_, err = io.ReadFull(reader, flowBytes)
+		case 5: // I32
+			var i32 [4]byte
+			_, err = io.ReadFull(reader, i32[:])
 			if err != nil {
 				return nil, err
 			}
-			addons.Flow = string(flowBytes)
-		case (2 << 3) | 2:
-			seedLen, err := binary.ReadUvarint(reader)
+		case 1: // I64
+			var i64 [8]byte
+			_, err = io.ReadFull(reader, i64[:])
 			if err != nil {
 				return nil, err
 			}
-			seedBytes := make([]byte, seedLen)
-			_, err = io.ReadFull(reader, seedBytes)
+		case 2: // LEN
+			var bytesLen uint64
+			bytesLen, err = binary.ReadUvarint(reader)
 			if err != nil {
 				return nil, err
 			}
-			addons.Seed = seedBytes
-		default:
-			return nil, fmt.Errorf("unknown protobuf message header: %v", protoHeader)
+			bytesData := make([]byte, bytesLen)
+			_, err = io.ReadFull(reader, bytesData)
+			if err != nil {
+				return nil, err
+			}
+			switch number {
+			case 1:
+				addons.Flow = string(bytesData)
+			case 2:
+				addons.Seed = bytesData
+			}
+		default: // group (3,4) has been deprecated we unneeded support
+			return nil, fmt.Errorf("unknown protobuf message tag: %v", tag)
 		}
 	}
 	return &addons, nil
@@ -48,14 +61,22 @@ func ReadAddons(data []byte) (*Addons, error) {
 func WriteAddons(addons *Addons) []byte {
 	var writer bytes.Buffer
 	if len(addons.Flow) > 0 {
-		writer.WriteByte((1 << 3) | 2)
-		writer.Write(binary.AppendUvarint(nil, uint64(len(addons.Flow))))
+		WriteUvarint(&writer, (1<<3)|2) // (field << 3) bit-or wire_type encoded as uint32 varint
+		WriteUvarint(&writer, uint64(len(addons.Flow)))
 		writer.WriteString(addons.Flow)
 	}
 	if len(addons.Seed) > 0 {
-		writer.WriteByte((2 << 3) | 2)
-		writer.Write(binary.AppendUvarint(nil, uint64(len(addons.Seed))))
+		WriteUvarint(&writer, (2<<3)|2) // (field << 3) bit-or wire_type encoded as uint32 varint
+		WriteUvarint(&writer, uint64(len(addons.Seed)))
 		writer.Write(addons.Seed)
 	}
 	return writer.Bytes()
 }
+
+func WriteUvarint(writer *bytes.Buffer, x uint64) {
+	for x >= 0x80 {
+		writer.WriteByte(byte(x) | 0x80)
+		x >>= 7
+	}
+	writer.WriteByte(byte(x))
+}