refactor add check header token

internal/util/jwt.go

@@ -1,6 +1,7 @@
 package util
 
 import (
+	"fmt"
 	"time"
 
 	"github.com/golang-jwt/jwt/v4"
@@ -35,6 +36,9 @@ func CreateToken(username string, userid uint64) (string, error) {
 func GetUser(tokenString string) string {
 	userClaim := &UserClaim{}
 	token, err := jwt.ParseWithClaims(tokenString, userClaim, func(token *jwt.Token) (interface{}, error) {
+		if _, ok := token.Method.(*jwt.SigningMethodHMAC); !ok {
+			return nil, fmt.Errorf("unexpected signing method: %v", token.Header["alg"])
+		}
 		return []byte(secretKey), nil
 	})
 	if err != nil {