PHP Download Script

Posted on: 15 January 2011
By: admin
This is a PHP script that can be used to manage the download process. The advantages of using PHP script for handling the download process is we can prevent user to download the file directly, we can also limit the download speed to the desired speed, and we can also count how many times that file has been downloaded.
The script below has some features such as :
Configurable download speed.
Resumable download capability.

<?php
// If user click the download link
if(isset($_GET['filename'])){
        // The directory of downloadable files
        // This directory should be unaccessible from web
        $file_dir="/tmp/";
        // Replace the slash and backslash character with empty string
        // The slash and backslash character can be dangerous
        $file_name=str_replace("/", "", $_GET['filename']);
        $file_name=str_replace("\\", "", $file_name);
        // If the requested file is exist
        if(file_exists($file_dir.$file_name)){
                // Get the file size
                $file_size=filesize($file_dir.$file_name);
                // Open the file
                $fh=fopen($file_dir.$file_name, "r");
                // Download speed in KB/s
                $speed=5;
                // Initialize the range of bytes to be transferred
                $start=0;
                $end=$file_size-1;
                // Check HTTP_RANGE variable
                if(isset($_SERVER['HTTP_RANGE']) &&
                        preg_match('/^bytes=(\d+)-(\d*)/', $_SERVER['HTTP_RANGE'], $arr)){
                        
                        // Starting byte
                        $start=$arr[1];
                        if($arr[2]){
                                // Ending byte
                                $end=$arr[2];
                        }
                }
                // Check if starting and ending byte is valid
                if($start>$end || $start>=$file_size){
                        header("HTTP/1.1 416 Requested Range Not Satisfiable");
                        header("Content-Length: 0");
                }
                else{
                        // For the first time download
                        if($start==0 && $end==$file_size){
                                // Send HTTP OK header
                                header("HTTP/1.1 200 OK");
                        }
                        else{
                                // For resume download
                                // Send Partial Content header
                                header("HTTP/1.1 206 Partial Content");
                                // Send Content-Range header
                                header("Content-Range: bytes ".$start."-".$end."/".$file_size);
                        }
                        // Bytes left
                        $left=$end-$start+1;
                        // Send the other headers
                        header("Content-Type: application/octet-stream");
                        header("Accept-Ranges: bytes");
                        // Content length should be the bytes left
                        header("Content-Length: ".$left);
                        header("Content-Disposition: attachment; filename=".$file_name);
                        
                        // Read file from the given starting bytes
                        fseek($fh, $start);
                        // Loop while there are bytes left
                        while($left>0){
                                // Bytes to be transferred
                                // according to the defined speed
                                $bytes=$speed*1024;
                                // Read file per size
                                echo fread($fh, $bytes);
                                // Flush the content to client
                                flush();
                                // Substract bytes left with the tranferred bytes
                                $left-=$bytes;
                                // Delay for 1 second
                                sleep(1);
                        }
                }
                fclose($fh);
        }
        else{
                // If the requested file is not exist
                // Display error message
                echo "File not found!";
        }
        
        exit();
}
?>
<html>
<head>
        <title>Home</title>
</head>
<body>
        <a href="index.php?filename=file.pdf">Download</a>
</body>
</html>
?>
Tags:
php
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Anonymous (not verified)
Sun, 08/14/2011 - 23:25
You are here

PHP Download Script

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