file URL on s3 to match files on website hosted elsewhere - url

Question

First I apologize if this is a duplicate because I've looked everywhere and the answers are either for slightly different scenarios or I just can't get them to work.
My scenario:
Hosting a Drupal site on a platform that does not support files larger than 250mb. Client wants a zip file that is 500mb to be hosted on the site and the reasoning is so that the url to the file is the same as any other file on the site. They want the ability to easily remove the file and replace it with a new large file in the future.
UPDATE:
I was successful masking an s3 file url with CNAME for a subdomain, but that will not resolve the issue that it is a slightly different URL and would require it's own ssl cert.
I'm using the s3fs module to set the default file location for the site to the s3 bucket. Now while setting up a file manager module, elfinder, I can't get it to know the new location to manage the files. Elfinder assumes they are in the local default files location. Once I've resolved this, I can tackle the cname.

Answer 1

This is not a complete answer, just a bit of code i cannot put inside the comment.
This code generates temporary link to download private files, that stored on S3 bucket.
Use it like this:
$url = el_s3_getTemporaryLink('myaccesskey','mysecretkey','mybucket','linux.png', 1);// this link is alive for one minute.
Which will output something like: https://mybucket.s3.amazonaws.com/?sometoken
You can put that inside links like:
l('Download now', $url, ['external'=>true]);
<?php
if(!function_exists('el_crypto_hmacSHA1')){
/**
* Calculate the HMAC SHA1 hash of a string.
*
* #param string $key The key to hash against
* #param string $data The data to hash
* #param int $blocksize Optional blocksize
* #return string HMAC SHA1
*/
function el_crypto_hmacSHA1($key, $data, $blocksize = 64) {
if (strlen($key) > $blocksize) $key = pack('H*', sha1($key));
$key = str_pad($key, $blocksize, chr(0x00));
$ipad = str_repeat(chr(0x36), $blocksize);
$opad = str_repeat(chr(0x5c), $blocksize);
$hmac = pack( 'H*', sha1(
($key ^ $opad) . pack( 'H*', sha1(
($key ^ $ipad) . $data
))
));
return base64_encode($hmac);
}
}
if(!function_exists('el_s3_getTemporaryLink')){
/**
* Create temporary URLs to your protected Amazon S3 files.
*
* #param string $accessKey Your Amazon S3 access key
* #param string $secretKey Your Amazon S3 secret key
* #param string $bucket The bucket (bucket.s3.amazonaws.com)
* #param string $path The target file path
* #param int $expires In minutes
* #return string Temporary Amazon S3 URL
* #see http://awsdocs.s3.amazonaws.com/S3/20060301/s3-dg-20060301.pdf
*/
function el_s3_getTemporaryLink($accessKey, $secretKey, $bucket, $path, $expires = 5) {
// Calculate expiry time
$expires = time() + intval(floatval($expires) * 60);
// Fix the path; encode and sanitize
$path = str_replace('%2F', '/', rawurlencode($path = ltrim($path, '/')));
// Path for signature starts with the bucket
$signpath = '/'. $bucket .'/'. $path;
// S3 friendly string to sign
$signsz = implode("\n", $pieces = array('GET', null, null, $expires, $signpath));
// Calculate the hash
$signature = el_crypto_hmacSHA1($secretKey, $signsz);
// Glue the URL ...
$url = sprintf('http://%s.s3.amazonaws.com/%s', $bucket, $path);
// ... to the query string ...
$qs = http_build_query($pieces = array(
'AWSAccessKeyId' => $accessKey,
'Expires' => $expires,
'Signature' => $signature,
));
// ... and return the URL!
return $url.'?'.$qs;
}
}