Untitled

<?PHP
///must have this session_start, or it wont work
session_start();
//get the database connection
require_once("db.php");
//see if they are already logged in, if so they go to members page
if(isset($_SESSION['logged']) == true) {
  header("Location: index.php");
}
// see if you have submitted the log in form
if (isset($_POST['submit'])) {
    // see if they filled in username and password
   if(!$_POST['username'] || !$_POST['password']) {
     echo "<body bgcolor='black' text='white' link='white' alink='white' vlink='white'>You did not fill in a required field.</body>";
   }
   // encrypt the password, must have this function in registering script! or they will never match.
function enchsetenev($toencode,$times)
{
    $salt = 's+(_a*';
    for($zo=0;$zo<$times;$zo=$zo+1)
    {
        $toencode = hash('sha512',$salt.$toencode);
        $toencode = md5($toencode.$salt);
    }
    return $toencode;
}
$password = enchsetenev("{$_POST['password']}",500);
   // changing the $_POST so its easier to type, etc.
   $username = ($_POST['username']);
   $ip = $_SERVER['REMOTE_ADDR'];
   // checks it against the database
   $check = mysql_query("SELECT username, password FROM user WHERE username = '$username' AND password='$password'")or die(mysql_error());
    $now = mysql_query("SELECT COUNT(id) FROM `user` WHERE online != 'Offline' AND ip = '{$ip}'") or die(mysql_error());
// checks if you have 2 accounts logged on already
    $nw = mysql_fetch_array($now);
    if($nw['COUNT(id)'] == 2) { echo "<body bgcolor='black' text='white' link='white' alink='white' vlink='white'>You already have 2 accounts on already. Log one out first</body>";  }
   //Gives error if user doesn't exist
   $check2 = mysql_num_rows($check);
   if ($check2 == 0) {
     echo "<body bgcolor='black' text='white' link='white' alink='white' vlink='white'>That username / password combination does not exist.</body>";
}
  // if login is ok then we add a cookie
  $_SESSION['username'] = ($_POST['username']);
  $_SESSION['logged'] = true;
// update online status
$q=mysql_query("UPDATE `user` SET online='At Home',ip='{$ip}' WHERE username='{$_SESSION['username']}'") or die(mysql_error());

  //then redirect them to the members area
header("Location: index.php");
  } else {
?>
        <body bgcolor='black' text='white' link='white' alink='white' vlink='white'>
<table bgcolor='black' bordercolor='1166ff' border='1' align='center'><tr><td>
    <form action="<?PHP echo $_SERVER['PHP_SELF']; ?>" method="POST">
<table border="0" align="center">
<tr><td colspan="2"><h3 align="center"><u>Login</u></h1></td></tr>
<tr><td>Username:</td><td>
<input type="text" name="username" maxlength="40">
</td></tr>
<tr><td>Password:</td><td>
<input type="password" name="password" maxlength="50">
</td></tr>
<tr><td colspan="2" align="right">
<input type="submit" name="submit" value="Login">
</td></tr>
</table></tr></td></table>
</form>
<center><a href='reg.php'>Click Here to Create an Account</a></center></body><?PHP } ?>