Set allowed protocols
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_PROTOCOLS, long bitmask);
Pass a long that holds a bitmask of CURLPROTO_* defines. If used, this bitmask limits what protocols libcurl may use in the transfer. This allows you to have a libcurl built to support a wide range of protocols but still limit specific transfers to only be allowed to use a subset of them. By default libcurl will accept all protocols it supports. See also CURLOPT_REDIR_PROTOCOLS(3).
All protocols built-in
Added in 7.19.4
Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not.