<?php
require_once('config.php');
require_once('class.db.php');

function file_force_download($file, $conn) {
  if (file_exists($file)) {
    if (ob_get_level()) {
      ob_end_clean();
    }
    header('Content-Description: File Transfer');
    header('Content-Type: application/octet-stream');
    header('Content-Disposition: attachment; filename=' . basename($file));
    header('Content-Transfer-Encoding: binary');
    header('Expires: 0');
    header('Cache-Control: must-revalidate');
    header('Pragma: public');
    header('Content-Length: ' . filesize($file));

    if ($fd = fopen($file, 'rb')) {
      while (!feof($fd)) {
        print fread($fd, 1024);
      }
      fclose($fd);
    }

    // close session
    $hash = sha1($_SERVER["HTTP_USER_AGENT"]);
    $ip = $_SERVER["REMOTE_ADDR"];
        $database = new DB();
        $conn--;
        if($conn==0){
            $delete = [
                'ip' => $ip,
                'hash' => $hash
            ];
            $deleted = $database->delete('sessions', $delete, 1);
        }else{
            $record = [
                'conn' => $conn
            ];
            $where_clause = [
                'ip' => $ip,
                'hash' => $hash
            ];
            $updated = $database->update('sessions', $record, $where_clause, 1);
        }

    exit;
  }
}

function check_access(&$connections){
    $database = new DB();
    $hash = sha1($_SERVER["HTTP_USER_AGENT"]);
    $ip = $_SERVER["REMOTE_ADDR"];
    $conn = 1;

    $query = "SELECT conn FROM sessions WHERE ip='$ip' AND hash='$hash'";
    if( $database->num_rows( $query ) > 0 )
    {
        list($curr_conn) = $database->get_row( $query );
        $conn = $curr_conn + 1;
        if($conn > 3) return false;

        $record = [
            'conn' => $conn
        ];
        $where_clause = [
            'ip' => $ip,
            'hash' => $hash
        ];
        $updated = $database->update('sessions', $record, $where_clause, 1);

    }else{
        $record = [
            'ip' => $ip,
            'hash' => $hash,
            'conn' => 1
        ];
        $add_query = $database->insert('sessions', $record);
    }
    $connections = $conn;
    return true;
}

$check = ['site1.su', 'site2.ru'];

if(!in_array($_SERVER['SERVER_NAME'], $check)){
    if(empty($config['access_denied'])){
        header("HTTP/1.1 500 Internal Server Error");
    }else{
        // redirect
        header("Location: ".$config['access_denied'], true, 303);
    }
}
$conn=0;
$access = check_access($conn);
if(!$access){
    if(empty($config['limit_exceeded'])){
        header("HTTP/1.1 500 Internal Server Error");
    }else{
        // redirect
        header("Location: ".$config['limit_exceeded'], true, 303);
    }
}
$file = $_GET['f'];
file_force_download($config['origin'].$file, $conn);