PHP, Dropbox API, OAuth signature and Non-latin symbols - php

Question

I have the PHP application integrated with Dropbox API. It worked good but since some time ago it stopped to work with non-latin symbols.
For example, if i try to create a dropbox folder with the API and use Cyrillic letters in folder name then API requests fail with error {"error": "Unauthorized"}
I have the PHP function
function createOAuthSignature($apiurl, $params, $oauth_secret, $oauth_token_secret, $method='GET'){
$urlencoded_apiurl = urlencode($apiurl);
$urlencoded_params = urlencode($params);
$basestring = $method .'&'.$urlencoded_apiurl.'&'.$urlencoded_params;
$oauth_signature = base64_encode(hash_hmac('sha1', $basestring, $oauth_secret.'&'.$oauth_token_secret, true));
$oauth_signature = urlencode($oauth_signature);
return $oauth_signature;
}
And the calling code is
$fullname = $parent . $foldername;
$fullnameEnc = rawurlencode($fullname);
$apiurl = $this->api_url .'fileops/create_folder/';
$params = 'oauth_consumer_key='.$this->oauth_consumer_key
.'&oauth_nonce='. $this->createNonce()
.'&oauth_signature_method=HMAC-SHA1'
.'&oauth_timestamp='. time()
.'&oauth_token='.$oauth_token
.'&oauth_version=1.0'
.'&path='. $fullnameEnc
.'&root=dropbox';
$oauth_signature = $this->createOAuthSignature($apiurl, $params, $this->oauth_secret, $oauth_token_secret);
$params .= '&oauth_signature='.$oauth_signature;
$action = $apiurl .'?'. $params;
$s = $this->curl->get($action);
What can be the problem there? I presume it is related to signature generating. But what is wrong there? This code worked fine just couple weeks ago.
Thanks

Answer 1

As Greg mentioned in a comment above, we're investigating, but if you want to switch to PLAINTEXT signing, it's quite easy. Change createOAuthSignature to just do this:
function createOAuthSignature($apiurl, $params, $oauth_secret, $oauth_token_secret, $method='GET'){
return urlencode($oauth_secret.'&'.$oauth_token_secret);
}
And in the calling code, change the signature method to PLAINTEXT:
$params = ...
.'&oauth_signature_method=PLAINTEXT'
...