download.php

<?php
/**
 * Copyright 2012 Armand Niculescu - MediaDivision.com
 * Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
 * 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
 * THIS SOFTWARE IS PROVIDED BY THE FREEBSD PROJECT "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FREEBSD PROJECT OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
/**
 * This version is modified to be used as an example for authentication on Stack Overflow for the question:
 *   http://stackoverflow.com/questions/16004906/how-to-prevent-non-members-from-directly-accessing-private-content-with-php
 * This modification does not imply a fully working example - as the authorization needs to be put in place
 * correctly by the user of the script.
 */


// hide notices
@ini_set('error_reporting', E_ALL & ~ E_NOTICE);

//- turn off compression on the server
@apache_setenv('no-gzip', 1);
@ini_set('zlib.output_compression', 'Off');

// get the file request, throw error if nothing supplied
if(!isset($_REQUEST['file']) || empty($_REQUEST['file']))
{
    header("HTTP/1.0 400 Bad Request");
    exit;
}

/******************************
 * PERFORM AUTHORIZATION HERE *
 *   The following is added   *
 ******************************/
if($_SESSION['validated'] !== true) {
    //Not authorized to download, send header and exit
    header("HTTP/1.0 401 Unauthorized");
    exit;
}

// sanitize the file request, keep just the name and extension
// also, replaces the file location with a preset one ('./content/' in this example)
$file_path  = $_REQUEST['file'];
$path_parts = pathinfo($file_path);
$file_name  = $path_parts['basename'];
$file_ext   = $path_parts['extension'];
$file_path  = './content/' . $file_name;

// allow a file to be streamed instead of sent as an attachment
$is_attachment = isset($_REQUEST['stream']) ? false : true;

// make sure the file exists
if (is_file($file_path))
{
    $file_size  = filesize($file_path);
    $file = @fopen($file_path,"rb");
    if ($file)
    {
        // set the headers, prevent caching
        header("Pragma: public");
        header("Expires: -1");
        header("Cache-Control: public, must-revalidate, post-check=0, pre-check=0");
        header("Content-Disposition: attachment; filename=\"$file_name\"");

        // set appropriate headers for attachment or streamed file
        if ($is_attachment)
                header("Content-Disposition: attachment; filename=\"$file_name\"");
        else
                header('Content-Disposition: inline;');

        // set the mime type based on extension, add yours if needed.
        $ctype_default = "application/octet-stream";
        $content_types = array(
                "exe" => "application/octet-stream",
                "zip" => "application/zip",
                "mp3" => "audio/mpeg",
                "mpg" => "video/mpeg",
                "avi" => "video/x-msvideo",
        );
        $ctype = isset($content_types[$file_ext]) ? $content_types[$file_ext] : $ctype_default;
        header("Content-Type: " . $ctype);

        //check if http_range is sent by browser (or download manager)
        if(isset($_SERVER['HTTP_RANGE']))
        {
            list($size_unit, $range_orig) = explode('=', $_SERVER['HTTP_RANGE'], 2);
            if ($size_unit == 'bytes')
            {
                //multiple ranges could be specified at the same time, but for simplicity only serve the first range
                //http://tools.ietf.org/id/draft-ietf-http-range-retrieval-00.txt
                list($range, $extra_ranges) = explode(',', $range_orig, 2);
            }
            else
            {
                $range = '';
                header('HTTP/1.1 416 Requested Range Not Satisfiable');
                exit;
            }
        }
        else
        {
            $range = '';
        }

        //figure out download piece from range (if set)
        list($seek_start, $seek_end) = explode('-', $range, 2);

        //set start and end based on range (if set), else set defaults
        //also check for invalid ranges.
        $seek_end   = (empty($seek_end)) ? ($file_size - 1) : min(abs(intval($seek_end)),($file_size - 1));
        $seek_start = (empty($seek_start) || $seek_end < abs(intval($seek_start))) ? 0 : max(abs(intval($seek_start)),0);

        //Only send partial content header if downloading a piece of the file (IE workaround)
        if ($seek_start > 0 || $seek_end < ($file_size - 1))
        {
            header('HTTP/1.1 206 Partial Content');
            header('Content-Range: bytes '.$seek_start.'-'.$seek_end.'/'.$file_size);
            header('Content-Length: '.($seek_end - $seek_start + 1));
        }
        else
          header("Content-Length: $file_size");

        header('Accept-Ranges: bytes');

        set_time_limit(0);
        fseek($file, $seek_start);

        while(!feof($file))
        {
            print(@fread($file, 1024*8));
            ob_flush();
            flush();
            if (connection_status()!=0)
            {
                @fclose($file);
                exit;
            }
        }

        // file save was a success
        @fclose($file);
        exit;
    }
    else
    {
        // file couldn't be opened
        header("HTTP/1.0 500 Internal Server Error");
        exit;
    }
}
else
{
    // file does not exist
    header("HTTP/1.0 404 Not Found");
    exit;
}
?>