From d854e0096c80e1a125a01d6bed47be6a5d30fec2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E6=BA=90=E6=96=87=E9=9B=A8?=
 <41315874+fumiama@users.noreply.github.com>
Date: Sun, 15 May 2022 19:37:34 +0800
Subject: [PATCH] add crc chksum

---
 gold/head/packet.go | 12 +++++++++---
 gold/link/recv.go   |  6 ++++++
 2 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/gold/head/packet.go b/gold/head/packet.go
index d7b3170..1ef28f7 100644
--- a/gold/head/packet.go
+++ b/gold/head/packet.go
@@ -4,6 +4,7 @@ import (
 	"encoding/binary"
 	"encoding/hex"
 	"errors"
+	"hash/crc64"
 	"net"
 
 	"github.com/fumiama/WireGold/helper"
@@ -56,8 +57,12 @@ func NewPacket(proto uint8, srcPort uint16, dst net.IP, dstPort uint16, data []b
 
 // Unmarshal 将 data 的数据解码到自身
 func (p *Packet) Unmarshal(data []byte) (complete bool, err error) {
-	if len(data) < 12 {
-		err = errors.New("data len < 12")
+	if len(data) < 60 {
+		err = errors.New("data len < 60")
+		return
+	}
+	if crc64.Checksum(data[:52], crc64.MakeTable(crc64.ISO)) != binary.LittleEndian.Uint64(data[52:60]) {
+		err = errors.New("bad crc checksum")
 		return
 	}
 
@@ -91,7 +96,7 @@ func (p *Packet) Unmarshal(data []byte) (complete bool, err error) {
 	}
 
 	if p.rembytes > 0 {
-		p.rembytes -= uint32(copy(p.Data[flags<<3:], data[52:]))
+		p.rembytes -= uint32(copy(p.Data[flags<<3:], data[60:]))
 	}
 
 	complete = p.rembytes == 0
@@ -129,6 +134,7 @@ func (p *Packet) Marshal(src net.IP, teatype uint8, datasz uint32, offset uint16
 		w.Write(p.Src.To4())
 		w.Write(p.Dst.To4())
 		w.Write(p.Hash[:])
+		w.WriteUInt64(crc64.Checksum(w.Bytes(), crc64.MakeTable(crc64.ISO)))
 		w.Write(p.Data)
 	})
 }
diff --git a/gold/link/recv.go b/gold/link/recv.go
index cf5337c..74c16dc 100644
--- a/gold/link/recv.go
+++ b/gold/link/recv.go
@@ -15,7 +15,13 @@ func (l *Link) Read() *head.Packet {
 }
 
 func (m *Me) wait(data []byte) *head.Packet {
+	if len(data) < 60 { // not a valid packet
+		return nil
+	}
 	flags := binary.LittleEndian.Uint16(data[10:12])
+	if flags&0x8000 == 0x8000 { // not a valid packet
+		return nil
+	}
 	logrus.Debugln("[recv]", len(data), "bytes data with flag", hex.EncodeToString(data[10:12]))
 	if flags == 0 || flags == 0x4000 {
 		h := head.SelectPacket()