Stk-code: Allow WAN without use of online.supertuxkart.net

[DarkArc]

After some investigation, it seems SuperTuxKart only allows WAN play if a user is associated with the server, and a connection can be validated against online.supertuxkart.net.

This creates unnecessary coupling with online.supertuxkart.net. If online.supertuxkart.net is ever down, that inherently breaks multiplayer for all servers, and there's no option for direct connection.

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Motivation:

I discovered this after struggling through what I originally believed to be a block on an IP range my game server resides on. Eventually it was determined that my host was blocking all traffic to/from digitial ocean due to a large number of attacks against their network.

[Alayan-stk-2]

The server list is retrieved by the clients from the addons website.

While the server could otherwise work independently, there would be no way for users to discover your server even exist, limiting its use to people to which you'd give the direct IP address to connect to (and as it's impractical, it wouldn't be used except possibly by your friends).

[DarkArc]

While the server could otherwise work independently, there would be no way for users to discover your server even exist, limiting its use to people to which you'd give the direct IP address to connect to (and as it's impractical, it wouldn't be used except possibly by your friends).

I'm okay with that, it's been pretty standard that, that be an option in my experience. Some groups also prefer to hide their servers -- ex for use in tournaments -- to prevent exposure to DDoS attacks.

[cgarz]

This should be an option.
Direct connection has been in most things for decades. It definitely wouldn't be impractical.
Certainly less impractical than telling everyone to install hamachi or something.

[Benau]

I added "LAN server can be connected too by typing your server public address (with port) in Enter server address dialog without relying on stk-addons." in NETWORKING.md, actually some stk fans already knows this https://github.com/supertuxkart/stk-code/issues/4295

[DarkArc]

This works for WAN servers?

[Benau]

if WAN player wants to connect your hidden server they need to type ip address anyway

[Benau]

you can disable validation player in xml so anyone without stk-addons account can connect by typing address too, some current stk servers already have that