new server

models/message.go

@@ -1,6 +1,48 @@
 package models
 
+import (
+	"encoding/binary"
+	"errors"
+)
+
 type Message struct {
-	Type    int8
-	Payload interface{}
+	Type    uint16
+	Version uint16
+	Payload []byte
+}
+
+func (m *Message) Encode() []byte {
+	payloadLen := len(m.Payload)
+	if payloadLen > 0xFFFF {
+		return nil
+	}
+
+	buf := make([]byte, 8+payloadLen)
+
+	binary.LittleEndian.PutUint16(buf[0:2], m.Type)
+	binary.LittleEndian.PutUint16(buf[2:4], m.Version)
+	binary.LittleEndian.PutUint16(buf[4:6], uint16(payloadLen))
+
+	copy(buf[8:], m.Payload)
+	return buf
+}
+
+func Decode(data []byte) (*Message, error) {
+	if len(data) < 8 {
+		return nil, errors.New("message too short")
+	}
+
+	payloadLen := binary.LittleEndian.Uint16(data[4:6])
+	if len(data) != int(8+payloadLen) {
+		return nil, errors.New("invalid payload length")
+	}
+
+	msg := &Message{
+		Type:    binary.LittleEndian.Uint16(data[0:2]),
+		Version: binary.LittleEndian.Uint16(data[2:4]),
+		Payload: make([]byte, payloadLen),
+	}
+
+	copy(msg.Payload, data[8:])
+	return msg, nil
 }