Server Status Ping API

[stephan-gh]

Adds an API for #331 to the SpongeAPI. This implements most things mentioned there except direct access to protocol versions, instead there is a (currently) read-only wrapper around them as GameVersion.

I decided to use the newer names from the protocol rewrite in 1.7 instead of the older names from the legacy ping. That's why "server list ping" is "status ping" and "MotD" is "description" now. This matches these names to the ones used in the protocol and the Minecraft source, and should also prevent confusion about "MotD" in the server list, or "MotD" as the message if you join a server (like used by Essentials) in the future.

[dobrakmato]

Is Favicon the right name for the class? Wouldn't the ServerIcon or just Icon be better?

[stephan-gh]

@dobrakmato Favicon is the named used in the protocol and in Minecraft internally. It's the name I have always used for this, but I can change it if others agree that it should be named differently.

[maxov]

throws IOException, FileNotFoundException

[stephan-gh]

This is already included in IOException (FileNotFoundException is a subclass of IOException) and IntelliJ IDEA doesn't stop with complaining that it is already defined.

[maxov]

This seems mostly okay, but I would also try to consider the 'streaming favicon' use case, a-la ServerListPlus 😉. How would one implement that in this API? Could they? Most likely that would require a ProtocolLib analog, but still an interesting thought.

[stephan-gh]

@gratimax I have considered that, but as explained in #331 (comment), it's basically just a bug on the client that is making this possible, there is nothing in the protocol that would allow this. The client is just not validating the packets sent by the server, so by resending the status response packet again and again it will keep the connection open infinitely.

This is not hard to fix on the client and requires quite some modifications on the server (and has some other problems on the client caused by this), so this is not something that should be in the SpongeAPI. However, it should be possible for mods to extend this API and add new functionality.

[Aaron1011]

The precise effect of cancelling this event should be documented, as a Vanilla client always expects a response.

[stephan-gh]

@Aaron1011 Added.