* Make the legacy ping handler more reliable
The Minecraft server often fails to respond to old ("legacy") pings
from old Minecraft versions using the protocol used before the switch
to Netty in Minecraft 1.7.
Due to packet fragmentation[1], we might not have all needed bytes
available when the LegacyPingHandler is called. In this case, it will
run into an error, remove the handler and continue using the modern
protocol.
This is unlikely to happen for the first two revisions of the legacy
ping protocol (used in Minecraft 1.5.x and older) since the request
consists of only one or two bytes, but happens frequently for the
last/third revision introduced in Minecraft 1.6.
It has much larger, variable packet sizes due to the inclusion of
the virtual host (the hostname/port used to connect to the server).
The solution[2] is simple: If we find more than two matching bytes,
we buffer the remaining bytes until we have enough to fully read and
respond to the request.
[1]: https://netty.io/wiki/user-guide-for-4.x.html#wiki-h3-11
[2]: https://netty.io/wiki/user-guide-for-4.x.html#wiki-h4-13
* Add legacy ping support to PaperServerListPingEvent
Add a new method to StatusClient check if the client is a legacy
client that does not support all of the features provided in the
event.
Some plugins (e.g. older builds of EssentialsX) assume that
ServerListPingEvent.getSampleText() returns a mutable copy of
the player sample list. This was the case until it was refactored
on top of the new API introduced in #980.
As a result, they may run into an error when trying to modify the
returned list directly. Modify getSampleText() to return a mutable
copy (a plain ArrayList) to mimic the old behavior.
* Drop original implementation for old player sample API
* Add extended PaperServerListPingEvent
Add a new event that extends the original ServerListPingEvent
and allows full control of the response sent to the client.
* Implement deprecated player sample API
Minecrell