How Can I Implement Resumable Downloads in PHP While Protecting File Paths?

Resumable Downloads in PHP Scripting

When tunneling file downloads through PHP scripts to safeguard file paths, it becomes evident that default methods do not support resumable downloads. To address this issue, consider the following solution:

The crux of supporting resumable downloads is to implement partial content handling. To initiate this, send the Accept-Ranges: bytes header in all responses, indicating support for partial content.

Upon receiving a request with the Range: bytes=x-y header, parse the range specified by the client. Open the file, seek to byte x, and send the requested y - x bytes. Additionally, set the response status to HTTP/1.0 206 Partial Content.

Here is a basic PHP code snippet that loosely follows this approach:

$filesize = filesize($file);

if (isset($_SERVER['HTTP_RANGE'])) {
    $partialContent = true;
    preg_match('/bytes=(\d+)-(\d+)?/', $_SERVER['HTTP_RANGE'], $matches);

    $offset = intval($matches[1]);
    $length = intval($matches[2]) - $offset;
} else {
    $partialContent = false;
}

$file = fopen($file, 'r');
fseek($file, $offset);

$data = fread($file, $length);
fclose($file);

if ($partialContent) {
    header('HTTP/1.1 206 Partial Content');
    header('Content-Range: bytes ' . $offset . '-' . ($offset + $length) . '/' . $filesize);
}

header('Content-Type: ' . $ctype);
header('Content-Length: ' . $filesize);
header('Content-Disposition: attachment; filename="' . $fileName . '"');
header('Accept-Ranges: bytes');

print($data);

By incorporating this mechanism, you enable resumable downloads while maintaining the privacy of file locations by utilizing PHP scripting for tunneling.

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