check checksum before load snapshot

server.go

@@ -4,10 +4,12 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
+	"hash/crc32"
 	"io/ioutil"
 	"os"
 	"path"
 	"sort"
+	"strconv"
 	"sync"
 	"time"
 )
@@ -1048,9 +1050,9 @@ func (s *Server) LoadSnapshot() error {
 	// TODO check checksum first
 
 	var snapshotBytes []byte
-	var checksum []byte
+	var checksumByte []byte
 
-	n, err := fmt.Fscanf(file, "%08x\n", &checksum)
+	n, err := fmt.Fscanf(file, "%v\n", &checksumByte)
 
 	if err != nil {
 		return err
@@ -1060,17 +1062,36 @@ func (s *Server) LoadSnapshot() error {
 		return errors.New("Bad snapshot file")
 	}
 
-	snapshotBytes, _ = ioutil.ReadAll(file)
-	debugln(string(snapshotBytes))
-
-	err = json.Unmarshal(snapshotBytes, &s.lastSnapshot)
+	checksum, err := strconv.ParseUint(string(checksumByte), 10, 32)
 
 	if err != nil {
 		return err
 	}
 
+	snapshotBytes, _ = ioutil.ReadAll(file)
+	debugln(string(snapshotBytes))
+
+	// Generate checksum.
+	byteChecksum := crc32.ChecksumIEEE(snapshotBytes)
+
+	if uint32(checksum) != byteChecksum {
+		fmt.Println(checksum, " ", byteChecksum)
+		return errors.New("bad snapshot file")
+	}
+
+	err = json.Unmarshal(snapshotBytes, &s.lastSnapshot)
+
+	if err != nil {
+		fmt.Println("unmarshal error")
+		return err
+	}
+
 	err = s.stateMachine.Recovery(s.lastSnapshot.State)
 
+	if err != nil {
+		fmt.Println("recovery error")
+	}
+
 	for _, peerName := range s.lastSnapshot.Peers {
 		s.AddPeer(peerName)
 	}

snapshot.go

@@ -45,7 +45,7 @@ func (ss *Snapshot) Save() error {
 	checksum := crc32.ChecksumIEEE(b)
 
 	// Write snapshot with checksum.
-	if _, err = fmt.Fprintf(file, "%08x\n", checksum); err != nil {
+	if _, err = fmt.Fprintf(file, "%v\n", checksum); err != nil {
 		return err
 	}