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types/types.go

@@ -12,8 +12,69 @@
 
 package types
 
+import (
+	"encoding/json"
+	"math/rand"
+)
+
 type Msg struct {
 	MsgID int    `json:"msg_id"`
 	Seq   int64  `json:"seq"`
 	Msg   string `json:"msg"`
 }
+
+type pkg struct {
+	N  int
+	V1 []byte
+	V2 []byte
+	V3 []byte
+}
+
+func Marshal(msg *Msg) ([]byte, error) {
+	data, err := json.Marshal(msg)
+	if err != nil {
+		return nil, err
+	}
+	pk := &pkg{}
+	l := len(data)
+	for i := 0; i < l; i += 2 {
+		pk.N = 1
+		pk.V1 = append(pk.V1, data[i])
+		pk.V2 = append(pk.V2, uint8(rand.Intn(256)))
+		if i+1 < l {
+			pk.N = 2
+			pk.V3 = append(pk.V3, data[i+1])
+		}
+	}
+	return json.Marshal(pk)
+}
+
+func Unmarshal(data []byte) (*Msg, error) {
+	var pk = &pkg{}
+	err := json.Unmarshal(data, pk)
+	if err != nil {
+		return nil, err
+	}
+
+	var mds []byte
+	if pk.N == 1 {
+		l := len(pk.V3)
+		for i, v := range pk.V1 {
+			mds = append(mds, v)
+			if i < l {
+				mds = append(mds, pk.V3[i])
+			}
+		}
+	} else {
+		l := len(pk.V1)
+		for i, v := range pk.V3 {
+			if i < l {
+				mds = append(mds, pk.V1[i])
+			}
+			mds = append(mds, v)
+		}
+	}
+	res := &Msg{}
+	err = json.Unmarshal(mds, res)
+	return res, err
+}