How can I give download access to files outside public_html directory?

Question

I have files stored outside the public_html folder for security purposes. However, I would like to link to specific files somehow where a user could download one of these files.

I am using a jquery script that allows me to specify a server PATH as an upload folder, and it does upload outside the public_html folder.

The only problem is it requires me to specify a URL to the "upload path" which is used to download the files. I thought I might be able to something like:

public_html/redirect (contains htaccess which forwards all requests to "hiding" folder)

hiding (outside public_html)

A user clicks /redirect/file.doc and they download a file located at hiding/file.doc

Is this possible? If not, how can I give specific file download access to files outside of my public_html directory? I know I've seen it done on other scripts before...

Answer 1

You can do this with "php download handler":

You can use method like this one to return file contents and file information headers to users browser, just make sure that nothing else is outputted before this.

I suggest that you put this to separate file and call that for example download.php.

function returnFile( $filename ) {
    // Check if file exists, if it is not here return false:
    if ( !file_exists( $filename )) return false;
    header('Content-Description: File Transfer');
    header('Content-Type: application/octet-stream');
    // Suggest better filename for browser to use when saving file:
    header('Content-Disposition: attachment; filename='.basename($filename));
    header('Content-Transfer-Encoding: binary');
    // Caching headers:
    header('Expires: 0');
    header('Cache-Control: must-revalidate, post-check=0, pre-check=0');
    header('Pragma: public');
    // This should be set:
    header('Content-Length: ' . filesize($filename));
    // Clean output buffer without sending it, alternatively you can do ob_end_clean(); to also turn off buffering.
    ob_clean();
    // And flush buffers, don't know actually why but php manual seems recommending it:
    flush();
    // Read file and output it's contents:
    readfile( $filename );
    // You need to exit after that or at least make sure that anything other is not echoed out:
    exit;
}

Extending it for basic use:

// Added to download.php
if (isset($_GET['file'])) {
    $filename = '/home/username/public_files/'.$_GET['file'];
    returnFile( $filename );
}

Warning:

This is basic example and does not take into account that user may try to take some evil advantages of $_GET that is not properly sanitized.

This means basically that user can for example retrieve passwd file or some other sensitive information if certain conditions apply.

For example, retrieving /etc/passwd:

Just point browser to http://server.com/download.php?file=../../../etc/passwd and server returns that file. So before real use you should find out how to properly check and sanitize any user supplied arguments.