Difficulty validating the login

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I have this code for an application from an online store but since I’m new in php I’m having some difficulty validating the login because when submitting the form it accepts everything you have written, whether the user exists in the database or not. What I’m missing from?

php menu.:

<!doctype html>
<html>
<head>
  <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
  <title>Menu</title>


<?php
include ("estilos.php");
?>

</head>
<body>

<!-- menu -->
  <div class="menu">
    <ul>
      <p><img src="imagens/logo.png" height="50px" width="50px"></p>
      <p><h2>LOJA ONLINE LUIS NARCISO</h2></p>
      <li><?php echo "<a href='index.php'> Produtos </a>";?></li>
      <li><?php echo "<a href='carrinho.php'> Carrinho </a>";?></li>
      <li><?php echo "<a href='forum.php'> Fórum </a>";?></li>
      <li><?php echo "<a href='consultas.php'> Consultas </a>";?></li>
      <li><?php echo "<a href='login.php'> Login/Registar </a>";?></li>
      <li><?php
      session_start();
      if(!isset($_SESSION['username'])){
        echo "<font color='white'>Olá&nbsp&nbsp<b>convidado</font>";
      } else {
        echo "<font color='white'>Olá&nbsp&nbsp<b>".$_SESSION['username']."</b><a href='logout.php'>Logout</a></font>";
      };
      ?></li>
    </ul>
  </div>

</body>
</html>

login.php:

<!doctype html>
<html>
<head>
  <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
  <title>Carrinho</title>

<?php
include ("menu.php");
?>

</head>
<body>

    <!-- conteudo -->
    <div class="conteudo">
      <p><h1> Login/Registar </h1></p>

        <!-- formulario login -->
        <?php

        if(!isset($_SESSION['username']) ){
          if(!isset($_SESSION['']) and !isset($_SESSION['tentativas'])){
            $_SESSION['codigo']=md5(rand());
            $_SESSION['tentativas']=0;
            $_SESSION['tempo_espera']=0;
          }
          if($_POST){
            $_SESSION['tentativas']++;
            if($_SESSION['tentativas']>10 and $_SESSION['tempo_espera']==0){
              $_SESSION['tempo_espera']=time()+120;
            } else {
              if($_SESSION['codigo']==$_POST['codigo']){
                $conexao = mysqli_connect("localhost", "root", "", "loja_online_lnarciso");
                $hash = md5($_POST['password']);
                $query = "SELECT * FROM utilizadores WHERE username = '{$_POST['username']}' and password = '{$hash}'";
                $resultado = mysqli_query($conexao,$query);
                $_SESSION['username']=$_POST['username'];
                header("Location: {$_SERVER['PHP_SELF']}");
              } else {
                echo "formulário inválido!</br>";
              }
          }

          } else if($_SESSION['tentativas']<10) {
          ?>

        <form method="POST" action="">
          <table align="center" width="300" border="0">

            <tr>
              <td><label>ENTRAR</label></td>
            </tr>
            <tr>
              <td><label>Username</label></td>
              <td><input type="text" name="username"><br></td>
            </tr>
            <tr>
              <td><label>Password</label></td>
              <td><input type="password" name="password"><br></td>
            </tr>
            <tr>
              <td>&nbsp;</td>
              <input type="hidden" name="codigo" value="<?php echo $_SESSION['codigo']; ?>" />
              <td><input type="submit" value="login"></td>
            </tr>
            <tr>
              <td><?php echo "<a href='utilizadores.php'><font color='black'> Registar </a></font>";?></td>
            </tr>

          </table>
        </form>

        <?php }
        if($_SESSION['tempo_espera'] < time() and $_SESSION['tentativas']>10){
          $_SESSION['tempo_espera']=0;
          $_SESSION['tentativas']=0;
        }
      } else {
          echo "<center>Login efetuado com sucesso!</center>";
      }
        ?>

    </div>

</body>
</html>
php sql oop

  • Why are you in one condition $_POST, without any logical verification ?

1 answer

0

The code is not actually checking whether or not the user exists in the table. Analyzing the following lines...

$query = "SELECT * FROM utilizadores WHERE username = '{$_POST['username']}' and password = '{$hash}'";
$resultado = mysqli_query($conexao,$query);
$_SESSION['username']=$_POST['username'];

... note that in the first the query was prepared in the table; in the second the query was executed; but in the third, whether or not valid data returned, entered the user in the session, that is, the user login has been made.

You can test whether you returned a line in the result set:

$query = "SELECT * FROM utilizadores WHERE username = '{$_POST['username']}' and password = '{$hash}'";
$resultado = mysqli_query($conexao,$query);
// Confere se o validou o usuário
if(mysqli_num_rows($resultado) > 0) // "> 0" não é obrigatório            
    // Efetua o login
    $_SESSION['username']=$_POST['username'];
else
    // Destroy o valor da sessão só para garantir
    unset($_SESSION['username']);

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