Warn the players about potential VPN/tunnel usage over LAN netplay if the ping is too high

[JesseTG]

What would you like to see?

Players trying to use a VPN or tunnel for LAN netplay (as integrated by #242) aren't given any indication that what they're doing won't work; they'll just get in-game errors and timeouts. Unless we make it very obvious when and why this happens, I'll likely have to field a ton of support requests from hapless players who just want to trade Pokemon. This has already happened with the standalone team, and will probably happen again if this isn't addressed before the next release.

Local wireless for DS games expect very low latency, because they were implemented under the assumption that players would be sitting a few feet apart from each other. The Internet can't provide the <10ms ping needed for these games to work, which is why this form of netplay will only work on a LAN.

The challenge here is that there's no reliable way to definitely check for improper LAN usage; even if the netpacket interface exposed the other client's IP address, a VPN-linked node might still have a local address. So the next best solution is to track the ping time and display a warning if it exceeds some threshold. I'm gonna arbitrarily say a 20ms rolling average, but the specifics are negotiable.

Terms

• I agree to follow the code of conduct.
• I understand that melonDS DS is not developed or maintained by the authors of melonDS.
• I understand that the author develops this core in his spare time, and that he is under no obligation to respond to this feature request.