PHP Remote file streaming with Resume Support

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

Paused

Paused State

Resume

Finished

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

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.

What's the purpose of this? hiding urls only or just allowing members to download?

The way you described it, it's a bit tricky ...

1. The remote server your script will download from should support resuming downloads.
2. Your php script should check for 'Accept-Range' header & pass it through to the remote server (using sockets is your best option I guess) so your script is actually acting as a proxy.