[Mediawiki-api] action=upload throws 'uploaddisabled'

[Platonides]

Will Preston wrote:
>             curl_setopt($ch, CURLOPT_URL,
> "http://$server_name/w/api.php?action=upload&token=$edittoken&filename=$filename&url=http://$server_name/upload_tmp/$filename");

Are these variables already urlencoded?