Force File Download with PHP

download.php

<?php
/*
 * Force File Download.
 * Usage: http://example.com/download.php?file=./uploads/image.jpg
 *
 * There are a couple of *ninja* exit() as security guarantee, adapt as necessary.
 *
 */

// Grab the requested file's name.
$file_name = filter_input(INPUT_GET, 'file', FILTER_SANITIZE_STRING);

// Make sure it's a file before doing anything!
if (!is_file($file_name)) {
    http_response_code(404);
    exit;
}

// Required for IE.
if (ini_get('zlib.output_compression')) {
    ini_set('zlib.output_compression', 'Off');
}

// Get the file mime type using the file extension.
switch (strtolower(substr(strrchr($file_name, '.'), 1))) {
    case 'pdf':
        $mime = 'application/pdf';
        break;
    case 'zip':
        $mime = 'application/zip';
        break;
    case 'jpeg':
    case 'jpg':
        $mime = 'image/jpg';
        break;
    case 'mp3':
        $mime = 'audio/mpeg3';
        break;
    default:
        exit();
}

header('Pragma: public');   // Required.
header('Expires: 0');   // No cache.
header('Cache-Control: must-revalidate, post-check=0, pre-check=0');
header('Last-Modified: ' . gmdate('D, d M Y H:i:s', filemtime($file_name)) . ' GMT');
header('Cache-Control: private', false);
header('Content-Type: ' . $mime);
header('Content-Disposition: attachment; filename="' . basename($file_name) . '"');
header('Content-Transfer-Encoding: binary');
header('Content-Length: ' . filesize($file_name));  // Provide file size.
header('Connection: close');
readfile($file_name);   // Push it out.
exit();