1 simultaneous download + force waiting time + Amazon S3

Question

I must say this is the first time I ask anything here, and I'm not a developer, so please be patient with my lack of knownledge. This requirement is for a website I am creating with some friends, so it's not that I'm making money with this.

This is the problem: I want to implement some kind of restriction to downloads, very much in the same way Rapidshare or any other file sharing service does:

1. The user should be able to download only 1 file simultaneously

2. The user should wait before being able to download another file, let's say 2 hours.

However, I am not trying to create a file sharing website. I am going to upload all the files to Amazon S3, and the only thing I need is to be able to restrict the downloads. I will create the links to the files. I don't care if users are registered or not, they should be able to download anyway.

The website is built in Joomla!, which uses Apache + MySQL. The files would be located at Amazon's servers.

My question is the following. Is there any way to implement this in a not-so-extremely-complicated way? Do you know some script or web-service that could help me get this done?

I have looked around, but the only thing I've found are Payment gateways, and we don't plan to charge for downloads.

Any help will be much appreciated.

Thanks!

UPDATE: I solved this problem using this script: http://www.vibralogix.com/linklokurl/features.php

Answer 1

As far as I know, there is no way to check on the current status of a download from S3. Having said that, S3 really does have plenty of bandwidth available, so I wouldn't worry too much about overloading their servers :) Just last week, Amazon announced that S3 is now serving an average of 650,000 objects / second.

If you want to implement something like @Pushpesh's solution in PHP, one solution would be to use the Amazon SDK for PHP and do something like this:

<?php
#Generate presigned S3 URL to download S3 object from

# Include AWS SDK for PHP and create S3
require_once("./aws-sdk/sdk.class.php"); 

$s3 = new AmazonS3();

# Let S3 know which file we want to be downloading
$s3_bucket_name = "yours3bucketname";
$s3_object_path = "folder1/object1.zip";
$s3_url_lifetime = "10 minutes";
$filename = "download.zip";

#Check whether the user has already downloaded a file in last two hours
$user_can_download = true; 

if($user_can_download) { 
    $s3_url = $s3->get_object_url($s3_bucket_name, $s3_object_path, $s3_url_lifetime, array('response' => array('content-type' => 'application/force-download', 'content-disposition' => 'attachment; filename={$filename}')));
    header("Location: {$s3_url}"); 
}
else { 
    echo "Sorry, you need to wait a bit longer before you can download a file again...";
}
?>

This uses the get_object_url function, which generates pre-signed URLs that allow you to let others download files you've set to private in S3 without making these files publicly available.

As you can see, the link this generates will only be valid for 10 minutes, and it's a unique link. So you can safely let people download from this link without having to worry about people spreading the link: the link will have expired. The only way people can get a new, valid link is to go through your download script, which will refuse to generate a new link if the IP/user that is trying to initiate a download has already exceeded their usage limit. It's important that you set these files to private in S3, though: if you make them publicly available, this won't do much good. You probably also want to take a look at the docs for the S3 API that generates these pre-signed URLs.

Answer 2

You can monitor user downloads by their ip address, store it in a database along with the time at which the user downloaded and the session id (with hashes of course) and check this before each download request. If the current time is less than 2 hours within the same session, block requests, else give them the download.

Table Structure:

Id       Ip_Addr      Session_Hash   Timestamp
1        10.123.13.67 sdhiehh_09#    1978478656
2        78.86.56.11  mkdhfBH&^#     1282973867
3        54.112.192.10 _)*knbh       1445465565

This is a very basic implementation. I'm sure more robust methods exist. Hope this helps.

Answer 3

If there is no plugin for that you won't be able to do it the easy way by adding a script or copy & paste "some" code.

So either hire somebody or you'll need to learn what you need to approach the task an your own, in other words learn how to program. Your question already contains the steps you need to implement: Record who is downloading what and when and keep track of the status of the download.

I have not tried to track a download status before but I'm not sure if it is possible to get the status somehow directly from the server that is sending the file. But you can get it from the client: Download Status with PHP and JavaScript

I'm further not sure if this will work properly in your scenario because the file will come from S3.

S3 itself has a so called feature "query string protection":

With Query string authentication, you have the ability to share Amazon S3 objects through URLs that are valid for a predefined expiration time.

So you need to lookup the S3 API to figure out how to implement this.

What you could try is to send an ajax request to your server when the user clicked the download link, send the amazon s3 link your server generated back as a response and have the client side javascript somehow trigger that file download then.

Answer 4

Only 2 ways comes to my mind - you either copy a file with unique hash and let apache serve it.. then you don't have any control over when user actually ends his download (or starts). Useful for big files. Another way is to pass it through php. Still, you would need to kill download session in case user stops download.