我的登录表单代码有什么问题？

Question

I got this code as part of my login form, but I tried and I can still login without even using a password. I changed everything to be case sensitive, my code seems to have no syntax errors, and I'm stumped.

if ($_POST['login']) {

$query= "SELECT * FROM users WHERE email='".mysqli_real_escape_string($link, $_POST['loginemail'])."' AND password='".md5(md5($_POST['loginemail'])+$_POST['loginpassword'])."' LIMIT 1";
$result= mysqli_query($link, $query);
$row= mysqli_fetch_array($result);

if ($row) {

    $_SESSION['id']= $row['id'];
  header("location:mainpage.php");

 } else {

  $error= "We could not find any user with the submitted informations!";
}

}

Answer 1

kindly do the following in order to troubleshoot the above

1. Enable error reporting in the beginning of script add below: error_reporting(E_ALL); ini_set('display_errors', 1);
2. var_dump the query and run in phpmyadmin / mysql console - ensure that everything is correct

The above will most likely show the problem if not then do post the corresponding html

Answer 2

I see you have twice the login + password received in your query. Is encrypted twice is not an issue? One hash is enough. For security, md5 () is not the best method, hash () is much better ( http://php.net/manual/fr/function.hash.php ). Especially with sha512 for $algo parameter. If you mutlitplies md5 , the imprint will never be good. Example with md5() :

$query= "SELECT * FROM users 
WHERE 
email='".mysqli_real_escape_string($link, $_POST['loginemail'])."' 
AND 
password='".hash('md5', $_POST['loginemail']+$_POST['loginpassword'])."' 
LIMIT 1";

Answer 3

Your not checked how many records are present in the result. Replace your code with bellow code, will work fine.

if ($_POST['login']) {

$query= "SELECT * FROM users WHERE email='".mysqli_real_escape_string($link, $_POST['loginemail'])."' AND password='".md5(md5($_POST['loginemail'])+$_POST['loginpassword'])."' LIMIT 1";
$result= mysqli_query($link, $query);


if ($result->num_rows==1) {
    $row= mysqli_fetch_array($result);    
    $_SESSION['id']= $row['id'];
    header("location:mainpage.php");
    exit(0);//Best practice to quit the execution after done the page redirection.
 } else {

  $error= "We could not find any user with the submitted informations!";
}

}