Untitled

<?php
session_start();
include "config.php";
if(isset($_POST['username']) && isset($_POST['password'])){
$username  = $_POST['username'];
$password  = $_POST['password'];
$query = $mysqli->query("SELECT * from prueba where username='$username' and password='$password'");
$row   = $query->fetch_assoc();
$user  = $row['username'];
$pass  = $row['password'];
$id    = $row['id_usuario'];
$bloquear = $row['bloquear'];
$usado = $row['usado'];

$sessionid=session_id();

if($username==$user && $password==$pass and $row>1){
  $query = $mysqli->query("UPDATE  prueba set idses='$sessionid' where id_usuario='$id'");

$query = $mysqli->query("SELECT * from prueba where id_usuario='$id' and idses='$sessionid'");
$row   = $query->fetch_assoc();

if($row['idses'] != $sessionid ){
alert('ya habia una sesión por favor logueate de nuevo');
echo "<script>window.location.href='contenido.php'</script>";
}
else{
  echo "<script>window.location.href='contenido.php'</script>";
}

$_SESSION['username']=$user;
$_SESSION['id_usuario']=$id;


?>
<script>window.location.href='contenido.php'</script>
<?php
}
else{

echo  "<script>window.location.href='curso_WWK9x9.php?errorusuario=si'</script>";
}
}
?>
<!DOCTYPE html>
<html lang="en">
  <head>
    <meta http-equiv="content-type" content="text/html; charset=UTF-8">
    <meta charset="utf-8">
    <title>Bienvenido</title>
    <meta name="generator" content="Bootply" />
    <meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1">
    <link href="css/bootstrap.min.css" rel="stylesheet">
    <link href="//netdna.bootstrapcdn.com/font-awesome/3.2.1/css/font-awesome.min.css" rel="stylesheet">
    <!--[if lt IE 9]>
      <script src="//html5shim.googlecode.com/svn/trunk/html5.js"></script>
    <![endif]-->

<link href="css/hoja.css" rel="stylesheet">

    <link href="css/styles.css" rel="stylesheet">


  </head>
  <body>
  <div class="container" >
<CENTER><h1 STYLE="color:white;">Bienvenido</h1></CENTER>
<br>
<center><img src="http://www.argoscursaradio.com/descargas/cursos/2016/cursonew/argoslogoblanco.png" class="img-responsive"   width="50%"  /></center>

<div class="col-md-4">

</div>
<?php  $error=$_GET["errorusuario"]; ?>

<!-- inicia div medio -->
<div class="col-md-4">
<center>
<section class="login-form">
        <form method="post">

          <input type="text" name="username" placeholder="usuario" required class="form-control input-lg"  style="margin-bottom: 20px;" />
          <input type="password" class="form-control input-lg" name="password" id="password" placeholder="Contraseña" style="margin-bottom: 20px;"  required="" />
          <button type="submit" name="go" class="btn btn-lg btn-primary btn-block">Entrar</button>
          <?php
if($error=="si"){
echo "<font color=red><center><b>Datos incorrectos</b></center></font>";
}?>
        </form>
        <center>
          <div id="final">
          <h3>Siguenos</h3>
          <div class="btn-group">
          <a class="btn btn-twitter" href="https://twitter.com/argoscursa" target="_blank"><i class="icon-twitter icon-large"></i> Twitter</a>
          <a class="btn btn-facebook" href="https://www.facebook.com/ArgosCursa-159244994166107/timeline/" target="_blank"><i class="icon-facebook icon-large"></i> Facebook</a>
          </div>
          <br>
          <p> ArgosCursa Derechos Reservados 2016 <p><br>
          <a href="aviso.php" style="color:white;">Aviso de Privacidad</a>
          </div>
        </center>
</section>
</center>
</div> <!-- termina div medio -->
<div class="col-md-4"></div>
</div>
</div>
<!-- script references -->
<script src="//ajax.googleapis.com/ajax/libs/jquery/2.0.2/jquery.min.js"></script>
<script src="js/bootstrap.min.js"></script>
</body>
</html>