Resumable downloads when using PHP to send the fil

Question

We are using a PHP scripting for tunnelling file downloads, since we don't want to expose the absolute path of downloadable file:

header("Content-Type: $ctype");
header("Content-Length: " . filesize($file));
header("Content-Disposition: attachment; filename=\"$fileName\"");
readfile($file);

Unfortunately we noticed that downloads passed through this script can't be resumed by the end user.

Is there any way to support resumable downloads with such a PHP-based solution?

Answer 1

You could use the below code for byte range request support across any browser

    <?php
$file = 'YouTube360p.mp4';
$fileLoc = $file;
$filesize = filesize($file);
$offset = 0;
$fileLength = $filesize;
$length = $filesize - 1;

if ( isset($_SERVER['HTTP_RANGE']) ) {
    // if the HTTP_RANGE header is set we're dealing with partial content

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

    $offset = intval($matches[1]);
    $tempLength = intval($matches[2]) - 0;
    if($tempLength != 0)
    {
        $length = $tempLength;
    }
    $fileLength = ($length - $offset) + 1;
} else {
    $partialContent = false;
    $offset = $length;
}

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

// seek to the requested offset, this is 0 if it's not a partial content request
fseek($file, $offset);

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

fclose($file);

if ( $partialContent ) {
    // output the right headers for partial content
    header('HTTP/1.1 206 Partial Content');
}

// output the regular HTTP headers
header('Content-Type: ' . mime_content_type($fileLoc));
header('Content-Length: ' . $fileLength);
header('Content-Disposition: inline; filename="' . $file . '"');
header('Accept-Ranges: bytes');
header('Content-Range: bytes ' . $offset . '-' . $length . '/' . $filesize);

// don't forget to send the data too
print($data);
?>

Answer 2

This worked very well for me: https://github.com/pomle/php-serveFilePartial

Answer 3

Yes. Support byteranges. See RFC 2616 section 14.35 .

It basically means that you should read the Range header, and start serving the file from the specified offset.

This means that you can't use readfile(), since that serves the whole file. Instead, use fopen() first, then fseek() to the correct position, and then use fpassthru() to serve the file.

Answer 4

If you're willing to install a new PECL module, the easiest way to support resumeable downloads with PHP is through http_send_file(), like this

<?php
http_send_content_disposition("document.pdf", true);
http_send_content_type("application/pdf");
http_throttle(0.1, 2048);
http_send_file("../report.pdf");
?>

source : http://www.php.net/manual/en/function.http-send-file.php

We use it to serve database-stored content and it works like a charm !

Answer 5

A really nice way to solve this without having to "roll your own" PHP code is to use the mod_xsendfile Apache module. Then in PHP, you just set the appropriate headers. Apache gets to do its thing.

header("X-Sendfile: /path/to/file");
header("Content-Type: application/octet-stream");
header("Content-Disposition: attachment; file=\"filename\"");

Answer 6

The top answer has various bugs.

1. The major bug: It doesn't handle Range header correctly. bytes a-b should mean [a, b] instead of [a, b), and bytes a- is not handled.
2. The minor bug: It doesn't use buffer to handle output. This may consume too much memory and cause low speed for large files.

Here's my modified code:

// TODO: configurations here
$fileName = "File Name";
$file = "File Path";
$bufferSize = 2097152;

$filesize = filesize($file);
$offset = 0;
$length = $filesize;
if (isset($_SERVER['HTTP_RANGE'])) {
    // if the HTTP_RANGE header is set we're dealing with partial content
    // find the requested range
    // this might be too simplistic, apparently the client can request
    // multiple ranges, which can become pretty complex, so ignore it for now
    preg_match('/bytes=(\d+)-(\d+)?/', $_SERVER['HTTP_RANGE'], $matches);
    $offset = intval($matches[1]);
    $end = $matches[2] || $matches[2] === '0' ? intval($matches[2]) : $filesize - 1;
    $length = $end + 1 - $offset;
    // output the right headers for partial content
    header('HTTP/1.1 206 Partial Content');
    header("Content-Range: bytes $offset-$end/$filesize");
}
// output the regular HTTP headers
header('Content-Type: ' . mime_content_type($file));
header("Content-Length: $filesize");
header("Content-Disposition: attachment; filename=\"$fileName\"");
header('Accept-Ranges: bytes');

$file = fopen($file, 'r');
// seek to the requested offset, this is 0 if it's not a partial content request
fseek($file, $offset);
// don't forget to send the data too
ini_set('memory_limit', '-1');
while ($length >= $bufferSize)
{
    print(fread($file, $bufferSize));
    $length -= $bufferSize;
}
if ($length) print(fread($file, $length));
fclose($file);