<?php
require_once("conf/login_conf.php");

if (isset($_GET['destroy'])) {
    $destr = clearData($_GET['destroy'],"int");
    if ($destr === 1) {
        session_destroy();
        setcookie("u","");
        setcookie("p","");
    } else {
        header("Location:".$_SERVER['HTTP_REFERER']);
    }
}

if (isset($_POST['submit'])) {
    if (isset($_POST['login'])) {
        $login = clearData($_POST['login'],"string");
        $pass = md5(clearData($_POST['pass'],"string"));
        $sql = "SELECT user_email,user_pass FROM user WHERE user_email='$login'";
        $res = mysql_query($sql,$dblink_us) or die(mysql_error());
        while ($row = mysql_fetch_assoc($res)){
            if ($pass == $row['user_pass']) {
                $_SESSION['user'] = $row['user_email'];
                if (isset($_POST['remember'])) {
                    setcookie("u",$login,time()+3600,"",$_SERVER['HTTP_HOST'], False, True);
                    setcookie("p",$pass,time()+3600,"",$_SERVER['HTTP_HOST'], False, True);
                }
                header("Location:".$_SERVER['HTTP_REFERER']);
            }
        }
        $_SESSION['warning'] = "логин или пароль неверен";
        header("Location:".$_SERVER['HTTP_REFERER']);
    }
} else {
    header("Location: index.php");
}
mysql_close($dblink_us);

<?php
//определяем константы для подключения к бд
define("HOST_USERS","localhost");
define("USER_USERS","general");
define("PASS_USERS","54321");
define("DB_USERS","users");
//подключение к СУБД
$dblink_us = mysql_connect(HOST_USERS,USER_USERS,PASS_USERS) or die (mysql_error());
//выбираем БД
mysql_select_db(DB_USERS,$dblink_us);
//установка кодировки UTF8
mysql_query("SET NAMES utf8",$dblink_us);
mysql_query("set character_set_client='utf8'",$dblink_us);
mysql_query("set character_set_results='utf8",$dblink_us);
mysql_query("set collation_connection='utf8_general_ci'",$dblink_us);

//сессия
session_start();

//функция "очистки" данных
function clearData ($data, $type="string")
{
    switch ($type)
    {
        case "string" :
            return mysql_real_escape_string(trim(strip_tags($data)));
        case "int" :
            return abs((int)$data);
    }
}

mysql_query("SET NAMES utf8",$dblink_us);

(int)$data

if (isset($_COOKIE['u'])) {
    if (!isset($_SESSION['user'])) {
        header("Location: login.php");
    }
}

if (isset($_COOKIE['u'])) {
    $u = clearData($_COOKIE['u'],"string");
    $p = clearData($_COOKIE['p'],"string");
    $sqlc = "SELECT user_email,user_pass FROM user WHERE user_email='$u'";
    $resc = mysql_query($sqlc,$dblink_us);
    $rowc = mysql_num_rows($resc);
    if ($rowc>0) {
        $c = mysql_fetch_assoc($resc);
        if ($p == $c['user_pass']) {
            $_SESSION['user'] = $c['user_email'];
        }
    } else {
        setcookie("u","");
        setcookie("p","");
    }
    header("Location: index.php");
}

if ($rowc)