Multi-Part PHP Download Script

This script provides a download path for files that are not within the web root. For example, you could host files from /w/media when your web root is /w/web, therefor giving you more control over your media file downloads (security, statistics, etc.). It supports multi-part downloads.

Features

• Multipart download support (allows multi-threaded client downloads).
• Download resume after failure.
• Very large file support. Files are split into chunks for download, limiting memory usage.
• Key based download. Hides file path information from browser.

Dependencies

• Apache setup and configured with PHP and .htaccess support.
• Apache must support URL rewrites.
• $content_base and $default_content must be included in PHP open_base() path.
• PHP must be able to run code via exec() [PHP filesize() int overflow workaround]
• The 'file' command must be installed (on most Linux systems by default) [mime type detection]

Usage

This script tricks the web browser/downloader into thinking that the file being downloaded is a simple directory based download. Here's how it works.

1. Define your $content_base. If the file you want to download is in /w/media/file.mp4, then
   $content_base = /w/media/.

2. Setup your download directory. Drop the entire download directory into your web root. For example, if your web root is /w/web then your download directory could be /w/web/download. So, now you can call the download script by pointing your browser at http://{hostname}/download.

3. Create a download key. Within the page you are going to link from, take the full path of the file you want to download, remove the $content_base (i.e. /w/media/file.mp4 becomes file.mp4) and encode the string in PHP with base64_encode($string). This is your download key.

4. Create a link to the download script. You can down combine everything into a working download link. It should be in the following format. You can change this by modifying the rewrite rule in the .htaccess file.

http://{hostname}/download/key/{download_key}/name/{file_name}.{file_extension}

5. Display the link to a user, pass it to a media player, or do whatever else you need to do.

Legal

Copyright 2011 Matthew Colf mattcolf@mattcolf.com

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.