Logo Questions Linux Laravel Mysql Ubuntu Git Menu
 

PHP Remote file streaming with Resume Support

Firstly, I am aware of similar question being asked before.

The subject pretty much explains the question but still,

the file is hosted on another server, the user will download file via my script, streamed to him...

But the problem is user can't resume it once paused...any solutions?

like image 209
born2hack Avatar asked Dec 12 '09 18:12

born2hack


2 Answers

You can try implementing your own download script using Accept-Ranges and Content-Range here is a prof of concept :

set_time_limit(0);
$download = new ResumeDownload("word.dir.txt", 50000); //delay about in microsecs 
$download->process();

Using Internet Download Manager

Start

Start

Paused

Paused

Paused State

Paused State

Resume

Resume

Finished

enter image description here

Class Used

class ResumeDownload {
    private $file;
    private $name;
    private $boundary;
    private $delay = 0;
    private $size = 0;

    function __construct($file, $delay = 0) {
        if (! is_file($file)) {
            header("HTTP/1.1 400 Invalid Request");
            die("<h3>File Not Found</h3>");
        }

        $this->size = filesize($file);
        $this->file = fopen($file, "r");
        $this->boundary = md5($file);
        $this->delay = $delay;
        $this->name = basename($file);
    }

    public function process() {
        $ranges = NULL;
        $t = 0;
        if ($_SERVER['REQUEST_METHOD'] == 'GET' && isset($_SERVER['HTTP_RANGE']) && $range = stristr(trim($_SERVER['HTTP_RANGE']), 'bytes=')) {
            $range = substr($range, 6);
            $ranges = explode(',', $range);
            $t = count($ranges);
        }

        header("Accept-Ranges: bytes");
        header("Content-Type: application/octet-stream");
        header("Content-Transfer-Encoding: binary");
        header(sprintf('Content-Disposition: attachment; filename="%s"', $this->name));

        if ($t > 0) {
            header("HTTP/1.1 206 Partial content");
            $t === 1 ? $this->pushSingle($range) : $this->pushMulti($ranges);
        } else {
            header("Content-Length: " . $this->size);
            $this->readFile();
        }

        flush();
    }

    private function pushSingle($range) {
        $start = $end = 0;
        $this->getRange($range, $start, $end);
        header("Content-Length: " . ($end - $start + 1));
        header(sprintf("Content-Range: bytes %d-%d/%d", $start, $end, $this->size));
        fseek($this->file, $start);
        $this->readBuffer($end - $start + 1);
        $this->readFile();
    }

    private function pushMulti($ranges) {
        $length = $start = $end = 0;
        $output = "";

        $tl = "Content-type: application/octet-stream\r\n";
        $formatRange = "Content-range: bytes %d-%d/%d\r\n\r\n";

        foreach ( $ranges as $range ) {
            $this->getRange($range, $start, $end);
            $length += strlen("\r\n--$this->boundary\r\n");
            $length += strlen($tl);
            $length += strlen(sprintf($formatRange, $start, $end, $this->size));
            $length += $end - $start + 1;
        }
        $length += strlen("\r\n--$this->boundary--\r\n");
        header("Content-Length: $length");
        header("Content-Type: multipart/x-byteranges; boundary=$this->boundary");
        foreach ( $ranges as $range ) {
            $this->getRange($range, $start, $end);
            echo "\r\n--$this->boundary\r\n";
            echo $tl;
            echo sprintf($formatRange, $start, $end, $this->size);
            fseek($this->file, $start);
            $this->readBuffer($end - $start + 1);
        }
        echo "\r\n--$this->boundary--\r\n";
    }

    private function getRange($range, &$start, &$end) {
        list($start, $end) = explode('-', $range);

        $fileSize = $this->size;
        if ($start == '') {
            $tmp = $end;
            $end = $fileSize - 1;
            $start = $fileSize - $tmp;
            if ($start < 0)
                $start = 0;
        } else {
            if ($end == '' || $end > $fileSize - 1)
                $end = $fileSize - 1;
        }

        if ($start > $end) {
            header("Status: 416 Requested range not satisfiable");
            header("Content-Range: */" . $fileSize);
            exit();
        }

        return array(
                $start,
                $end
        );
    }

    private function readFile() {
        while ( ! feof($this->file) ) {
            echo fgets($this->file);
            flush();
            usleep($this->delay);
        }
    }

    private function readBuffer($bytes, $size = 1024) {
        $bytesLeft = $bytes;
        while ( $bytesLeft > 0 && ! feof($this->file) ) {
            $bytesLeft > $size ? $bytesRead = $size : $bytesRead = $bytesLeft;
            $bytesLeft -= $bytesRead;
            echo fread($this->file, $bytesRead);
            flush();
            usleep($this->delay);
        }
    }
}

File Used

like image 114
Baba Avatar answered Nov 15 '22 15:11

Baba


If you're using PHP to serve the file, you have to implement all resuming logic yourself.

You'll have to send Accept-Ranges and respond appropriately to Ranges.

That's a chunk of work. It might be easier to use mod_proxy.

like image 34
Kornel Avatar answered Nov 15 '22 15:11

Kornel