Stop using cURL for backend

[LPGhatguy]

The libcurl API is not very nice to bind to, I should rewrite the library targeting a new HTTP backend if I can.

[MikuAuahDark]

Maybe you can get inspiration from this? https://bitbucket.org/bartbes/lua-https

It uses Schannel in Windows and NSURL for macOS and iOS. Unfortunately, I don't think it's possible to interact with Objective-C code and for Linux you still have to rely on cURL.

[LPGhatguy]

I also took a try at making an async HTTP library for Lua awhile ago: https://github.com/LPGhatguy/lua-async-http

[MikuAuahDark]

I mentioned that specifically because lua-https, indeed supports https. If your async HTTP library can't do HTTPS then it's a downgrade of luajit-request, which, I'm sure the reason why people use this library in the first place.

As per async, you can always use timeout of 0 seconds on recv/select so you know exactly when to yield. I use this approach with LuaSocket in a dedicated game server, since the server runs single threaded, and I can't use Lanes due to thread safety issue, I used timeout of 0 and check if I really return value.

[LPGhatguy]

The library I linked does do HTTPS, using platform APIs. No HTTP library is very useful without HTTPS support in 2020. 😅