<?php

function createsessions($username)
{
    $salt=uniqid(rand(), true);
    setcookie('cusername',hash('sha512',$username.$salt),time()+3600);
    setcookie('cid',hash('sha512',session_id(),$salt),time()+3600);
    setcookie('cauth',hash('sha512','yes',$salt),time()+3600);
    session_register();
    $_SESSION['susername'] = hash('sha512',$username,$salt);
    $_SESSION['sid'] = hash('sha512',session_id(),$salt);
    $_SESSION['sauth'] = hash('sha512','yes',$salt);
}

function deletesessions()
{
    unset($_SESSION['susername']);
    unset($_SESSION['sid']);
    unset($_SESSION['sauth']);
    session_unset();
    session_destroy();
    setcookie('cusername','',time()-3600);
    setcookie('cid','',time()-3600);
    setcookie('cauth','',time()-3600);
}

function login($username,$password) {
    $username = mysql_real_escape_string( stripslashes($_POST['username']));
    $password = mysql_real_escape_string( stripslashes($_POST['password']));

    $salt = '10367001714ecbe6c5f01862.28316256';
    $salt2 = '10868308824ecbe6c5f01750.38838567';
    $eusername = hash("sha512",$username.$salt2);
    $epassword = hash("sha512",$password.$salt);

    $saltquery = mysql_query("SELECT `usernamesalt` AND `passwordsalt` FROM `users` WHERE username='".$eusername."'");
        while($row = mysql_fetch_row($saltquery)) {
            $usernamesalt = $row['0'];
            $passwordsalt = $row['1'];
    }

    $check = mysql_query("SELECT * FROM `users` WHERE username='".$eusername."' and password='".$epassword."' LIMIT 1");
    $count = mysql_num_rows($check);
    if($count == 1)
    {
    return true;
    } else {
    return false;
    }
}

function checkauth() {
    if (isset($_SESSION['susername']) && isset($_SESSION['sid']) && isset($_SESSION['sauth']) && isset($_COOKIE['cusername']) && isset($_COOKIE['cid']) && isset ($_COOKIE['cauth'])) {
        if ($_SESSION['sid'] && $_COOKIES['cid'] == session_id && $_SESSION['susername'] && $_COOKIE['cusername'] == $_POST['username']) {
        return true;
        }
    }
    if (login($_POST['username'],$_POST['password'])) {
        createsessions($_POST['username']);
        return true;
    } else {
        deletesessions();
        return false;
    }
}

function loginform() {
    echo "
        <form method='POST' action='login.php'>
        <input type='text' name='username'><br>
        <input type='text' name='password'>
        <input type='submit' name='login' value='Submit'>
        </form>";
}
?>