How can I get my Amazon S3 encoding function to understand subfolders inside buckets? - amazon-s3

Question

I wrote the following function to encode my S3 links so that they handle Amazon's S3 encoding system to protect links. The trouble is that it only works if the file is in the bucket. If I make a subfolder to the bucket and stick the file in there, it's not working. What am I doing wrong?
function encodeS3($sURL,$sAccessKey,$sSecretKey,$nExpireMinutes = 5) {
$sFile = basename($sURL);
$sBucket = basename(str_replace('/' . $sFile,'',$sURL));
$asQuery = array(
'AWSAccessKeyId' => $sAccessKey,
);
$nExpireSecs = absint( $nExpireMinutes ) * 60;
$nExpireSecs = time() + absint( $nExpireSecs );
$asQuery[ 'Expires' ] = $nExpireSecs;
$sAmazonText = "GET\n\n\n{$nExpireSecs}\n/{$sBucket}/{$sFile}";
$asQuery[ 'Signature' ] = urlencode( base64_encode( ( hash_hmac( 'sha1', utf8_encode( $sAmazonText ), $sSecretKey, TRUE ) ) ) );
$s = add_query_arg( $asQuery, "https://s3.amazonaws.com/{$sBucket}/{$sFile}" );
return esc_url($s);
}

Answer 1

I just needed to change the way I was parsing the URL.
function encodeS3($sURL,$sAccessKey,$sSecretKey,$nExpireMinutes = 5) {
/*
$sFile = basename($sURL);
$sBucket = basename(str_replace('/' . $sFile,'',$sURL));
*/
$sURL = str_replace('https://','',$sURL);
$sURL = str_replace('http://','',$sURL);
$sURL = str_replace(urlencode('https://'),'',$sURL);
$sURL = str_replace(urlencode('http://'),'',$sURL);
$asParts = explode('/',$sURL);
array_shift($asParts);
$sBucket = array_shift($asParts);
$sFile = implode('/',$asParts);
$asQuery = array(
'AWSAccessKeyId' => $sAccessKey,
);
$nExpireSecs = absint( $nExpireMinutes ) * 60;
$nExpireSecs = time() + absint( $nExpireSecs );
$asQuery[ 'Expires' ] = $nExpireSecs;
$sAmazonText = "GET\n\n\n{$nExpireSecs}\n/{$sBucket}/{$sFile}";
$asQuery[ 'Signature' ] = urlencode( base64_encode( ( hash_hmac( 'sha1', utf8_encode( $sAmazonText ), $sSecretKey, TRUE ) ) ) );
$s = add_query_arg( $asQuery, "https://s3.amazonaws.com/{$sBucket}/{$sFile}" );
return esc_url($s);
}
BTW, the above uses some functions that are only available in WordPress. If you need straight PHP, you'll have to adjust this.