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|
package core
import (
"encoding/binary"
"fmt"
"io"
"strings"
)
type Marshaler interface {
Marshal() []any
}
type DataType uint8
const (
TypeUnknown DataType = 0x00
TypeHandshake = 0x01
TypePing = 0x02
TypePong = 0x03
TypeTest = 0xFF
)
type Handshake struct {
Version uint8
}
func (h Handshake) Marshal() []any {
return []any{h.Version}
}
func ReadHandshake(r io.Reader) (Handshake, error) {
var d Handshake
err := read(r, &d.Version)
return d, err
}
type Test struct {
Message string
}
func ReadTest(r io.Reader) (Test, error) {
var d Test
err := readString(r, &d.Message)
return d, err
}
func (h Test) Marshal() []any {
return []any{append([]byte(h.Message), 0x0)}
}
func Read(r io.Reader) (any, error) {
dType, err := ReadDataType(r)
if err != nil {
return nil, fmt.Errorf("cannot read data type", err)
}
switch dType {
case TypeUnknown:
return nil, fmt.Errorf("cannot read data type 0x00 (TypeUnknown)")
case TypeHandshake:
return ReadHandshake(r)
case TypeTest:
return ReadTest(r)
default:
return nil, fmt.Errorf("unsupported type: %v", dType)
}
}
func ReadDataType(r io.Reader) (DataType, error) {
var data uint8
if err := read(r, &data); err != nil {
return TypeUnknown, err
}
dType := DataType(data)
return dType, nil
}
func readString(r io.Reader, ptr *string) error {
var (
sb strings.Builder
buf byte
)
for {
if err := read(r, &buf); err != nil {
return err
}
if buf == 0x0 {
break
}
if err := sb.WriteByte(buf); err != nil {
fmt.Errorf("cannot write byte to string buffer: %v", err)
}
}
*ptr = sb.String()
return nil
}
func read(r io.Reader, ptr any) error {
err := binary.Read(r, binary.BigEndian, ptr)
if err != nil {
return fmt.Errorf("cannot read: %v", err)
}
return nil
}
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