ProtocolLib/Readme.md
2012-10-12 00:49:47 +02:00

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Markdown

ProtocolLib
===========
Certain tasks are impossible to perform with the standard Bukkit API, and may require
working with and even modify Minecraft directly. A common technique is to modify incoming
and outgoing [packets](http://www.wiki.vg/Protocol), or inject custom packets into the
stream. This is quite cumbersome to do, however, and most implementations will break
as soon as a new version of Minecraft has been released, mostly due to obfuscation.
Critically, different plugins that use this approach may _hook_ into the same classes,
with unpredictable outcomes. More than often this causes plugins to crash, but it may also
lead to more subtle bugs.
### Resources
* [JavaDoc](http://aadnk.github.com/ProtocolLib/Javadoc/)
Building
--------
You can compile this project yourself by using the latest version of Maven.
A new API
---------
__ProtocolLib__ attempts to solve this problem by providing a event API, much like Bukkit,
that allow plugins to monitor, modify or cancel packets sent and received. But more importantly,
the API also hides all the gritty, obfuscated classes with a simple index based read/write system.
You no longer have to reference CraftBukkit!
### Using ProtocolLib
To use the library, first add ProtocolLib.jar to your Java build path. Then, add ProtocolLib
as a dependency (or soft-dependency, if you can live without it) to your plugin.yml file:
depends: [ProtocolLib]
Future versions will be available in a public Maven repository, possibly on Maven central. But it
will always be possible to reference ProtocolLib manually.
Then get a reference to ProtocolManager in onLoad() and you're good to go.
private ProtocolManager protocolManager;
public void onLoad() {
protocolManager = ProtocolLibrary.getProtocolManager();
}
To listen for packets sent by the server to a client, add a server-side listener:
// Disable all sound effects
protocolManager.addPacketListener(
new PacketAdapter(this, ConnectionSide.SERVER_SIDE, ListenerPriority.NORMAL, 0x3E) {
@Override
public void onPacketSending(PacketEvent event) {
// Item packets
switch (event.getPacketID()) {
case 0x3E: // Sound effect
event.setCancelled(true);
break;
}
}
});
It's also possible to read and modify the content of these packets. For instance, you can create a global
censor by listening for Packet3Chat events:
// Censor
protocolManager.addPacketListener(
new PacketAdapter(this, ConnectionSide.CLIENT_SIDE, ListenerPriority.NORMAL, 0x03) {
@Override
public void onPacketReceiving(PacketEvent event) {
if (event.getPacketID() == 0x03) {
try {
PacketContainer packet = event.getPacket();
String message = packet.getSpecificModifier(String.class).read(0);
if (message.contains("shit") || message.contains("damn")) {
event.setCancelled(true);
event.getPlayer().sendMessage("Bad manners!");
}
} catch (FieldAccessException e) {
getLogger().log(Level.SEVERE, "Couldn't access field.", e);
}
}
}
});
### Sending packets
Normally, you might have to do something ugly like the following:
Packet60Explosion fakeExplosion = new Packet60Explosion();
fakeExplosion.a = player.getLocation().getX();
fakeExplosion.b = player.getLocation().getY();
fakeExplosion.c = player.getLocation().getZ();
fakeExplosion.d = 3.0F;
fakeExplosion.e = new ArrayList<Object>();
((CraftPlayer) player).getHandle().netServerHandler.sendPacket(fakeExplosion);
But with ProtocolLib, you can turn that into something more manageable. Notice that
you don't have to create an ArrayList this version:
PacketContainer fakeExplosion = protocolManager.createPacket(60);
fakeExplosion.getSpecificModifier(double.class).
write(0, player.getLocation().getX()).
write(1, player.getLocation().getY()).
write(2, player.getLocation().getZ());
fakeExplosion.getSpecificModifier(float.class).
write(0, 3.0F);
protocolManager.sendServerPacket(player, fakeExplosion);
Compatiblity
------------
One of the main goals of this project was to achieve maximum compatibility with CraftBukkit. And the end
result is quite flexible - in tests I successfully ran an unmodified ProtocolLib on CraftBukkit 1.8.0, and
it should be resiliant against future changes. It's likely that I won't have to update ProtocolLib for
anything but bug and performance fixes.
How is this possible? It all comes down to reflection in the end. Essentially, no name is hard coded -
every field, method and class is deduced by looking at field types, package names or parameter
types. It's remarkably consistent across different versions.
### Incompatiblity
The following plugins (to be expanded) are not compatible with ProtocolLib: