I would like to add support for CURLOPT_PROTOCOLS and CURLOPT_REDIR_PROTOCOLS (in curl_easy_setopt), but that requires some design choices to be made.

Both the options get a long that holds a bitmask of CURLPROTO_* defines from "curl.h", so:
1) In order to add those options to lua-curl, CURLPROTOs should be exposed somewhere in the lua module (note that the order in which protocols are listed in curl_version_info_data.protocols doesn't reflect the CURLPROTOs defines values, so they are not useful in this case);
2) keeping the api style, the new lua functions will accept one and only one long; in that case, since lua5.1 doesn't have official support for bitwise operations, users of that version must rely on external libraries for computing the protocols bitmask. Despite that seems cumbersome to me, I think that lua-curl won't benefit from a change in the api style.

Discussing the matter before implementing anything would be nice