While it may seem better to use a Spout PacketListener, we can't prevent other spout listeners from stopping the listener chain. For instance, Orebfuscator does supports Spout, but does this by cancelling every chunk packet and sending them to be processed and sent by Orebfuscator only. This can never be made compatible with other plugins. So, we choose to add some overhead and inject our proxy onto Spout. Fortunately, Spout injects the proxy using a player listener on LOWEST, so we get to override Spout again with our HIGHEST. The proxy method should be generic enough to handle most proxy types. |
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ItemDisguise | ||
ProtocolLib | ||
Readme.md |
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, 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
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]
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 achive 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: