HTTPDownload.php

<?php

function download($path, $name, $range = null)
{
    if (!file_exists($path)) {
        header("HTTP/1.1 404 Not Found");
        exit();
    }
    header("Pragma: public");
    header("Expires: -1");
    header("Cache-Control: must-revalidate, post-check=0, pre-check=0");
    header("Content-Type: application/octet-stream"); 
    header("Content-Disposition: attachment; filename='{$name}'");
    header("Accept-Ranges: bytes");

    if (!empty($range)) {
        list($size_unit, $range_orig) = explode('=', $range, 2);
        if ($size_unit == "bytes") {
            list($range, $extra_ranges) = explode(',', $range_orig, 2);
        } else {
            $range = "";
            header('HTTP/1.1 416 Requested Range Not Satisfiable');
            exit();
        }
    } else {
        $range = "";
    }

    $file_size  = filesize($path);
    list($seek_start, $seek_end) = explode('-', $range, 2);
    $seek_end   = (empty($seek_end)) ? ($file_size - 1) : min(abs(intval($seek_end)), ($file_size - 1));
    $seek_start = (empty($seek_start) || $seek_end < abs(intval($seek_start))) ? 0 : max(abs(intval($seek_start)), 0);

    if ($seek_start > 0 || $seek_end < ($file_size - 1)) {
        header("HTTP/1.1 206 Partial Content");
        header("Content-Range: bytes {$seek_start}-{$seek_end}/{$file_size}");
        header("Content-Length: ".($seek_end - $seek_start + 1));
    } else {
        header("Content-Length: {$file_size}");
    }

    $fd = fopen($path, "rb");
    fseek($fd, $seek_start);
    while(!feof($fd)) {
        echo fread($fd, 4096);
        ob_flush();
        if (connection_status() != 0) {
            @fclose($fd);
            exit;
        }
    } 

    fclose($fd);
}
?>