From f426b7b2cc3e630d4090004a5a883f8816c8eef8 Mon Sep 17 00:00:00 2001
From: wenyifan <evan.wen@movit-tech.com>
Date: Mon, 5 Sep 2022 16:08:24 +0800
Subject: [PATCH] update

---
 shadow/packer.go | 21 +++++++++++----------
 1 file changed, 11 insertions(+), 10 deletions(-)

diff --git a/shadow/packer.go b/shadow/packer.go
index 38bc828..1f8edad 100644
--- a/shadow/packer.go
+++ b/shadow/packer.go
@@ -8,7 +8,8 @@ import (
 )
 
 var (
-	AppDataHeader = []byte{0x17, 0x3, 0x3}
+	AppDataHeader = []byte("GGGGGGGG")
+	HeaderLength  = len(AppDataHeader)
 )
 
 type PackAppData struct {
@@ -17,11 +18,11 @@ type PackAppData struct {
 
 func (m PackAppData) Read(p []byte) (n int, err error) {
 	buf := make([]byte, 32*1024)
-	read, err := m.Conn.Read(buf[0:5])
-	if bytes.Equal(buf[0:3], AppDataHeader) {
-		u := int(binary.BigEndian.Uint16(buf[3:5]))
-		r, err := m.Conn.Read(buf[5 : u+5])
-		copy(p, buf[5:r+5])
+	read, err := m.Conn.Read(buf[0 : HeaderLength+2])
+	if bytes.Equal(buf[0:HeaderLength], AppDataHeader) {
+		u := int(binary.BigEndian.Uint16(buf[HeaderLength : HeaderLength+2]))
+		r, err := m.Conn.Read(buf[HeaderLength+2 : u+HeaderLength+2])
+		copy(p, buf[HeaderLength+2:r+HeaderLength+2])
 		return r, err
 	} else {
 		fmt.Println("Header is not present")
@@ -30,12 +31,12 @@ func (m PackAppData) Read(p []byte) (n int, err error) {
 }
 
 func (m PackAppData) Write(p []byte) (n int, err error) {
-	t := make([]byte, len(p)+5)
+	t := make([]byte, len(p)+HeaderLength+2)
 	copy(t[0:], AppDataHeader)
-	binary.BigEndian.PutUint16(t[3:], uint16(len(p)))
-	copy(t[5:], p)
+	binary.BigEndian.PutUint16(t[HeaderLength:], uint16(len(p)))
+	copy(t[HeaderLength+2:], p)
 	write, err := m.Conn.Write(t)
-	write = write - 5
+	write = write - HeaderLength - 2
 	return write, err
 }