Nlibcurl.rpl
The version of curl shipped with the Wii U includes a few extra options, mostly for configuring the SSL implementation.
Extra options
These options are passed to curl_easy_setopt.
CURLOPT_NSSL_CONTEXT
value: 210
The NSSLContext obtained from calling NSSLCreateContext. Required for SSL connections.
CURLOPT_UNKNOWN_211
value: 211
nn_ec.rpl sets this to 3.
CURLOPT_UNKNOWN_215
value: 215
nn_ec.rpl sets this to 0, doesn't appear to be handled in the actual library itself (returns an error?)