PacketEventsSK

Appearance

Packet Listening ​

To listen to packets with PacketEventsSK you can use a single syntax element: On Packet. Let's break it down.

Packet Processing ​

Packets in Minecraft are always processed on what is called the netty threads. This is a group of worker threads that handle all network communication for the server. This means that if you want to intercept a packet, your code must be processed on the same threads (note that you can still read the packets on the other threads). The problem with this is that most of paper's API is not thread safe and can only be accessed on what is called the main thread (or sync thread).

Netty Processing ​

This processing type should be used for the interception of packets.

applescript
# "netty processed" ensures the packet is processed on the netty threads.
# This is the default process type for the event.
on any packet netty processed:
    if event-packet is clientbound entity metadata packet:
        # This packet won't be sent
        cancel packet
    else if event-packet is serverbound chat message packet:
        # This packet won't be received
        cancel packet
    else if event-packet is clientbound entity metadata packet:
        # this is a clone of the packet's meta
        set {_meta} to packet meta of event-packet
        set meta glowing state of {_meta} to true
        # Sets to the clone
        set packet meta of event-packet to {_meta}

DANGER

Minecraft is not thread safe, you can not access most of paper's API on the netty threads. If you want to access paper's API, you must switch back to the main thread. Look into Run Task (SkBee) Run Section (Skript-Reflect).

Sync Processing ​

This processing type should be used for interacting with paper's API with the data of a packet.

applescript
on clientbound entity velocity sync processed:
	set {_id} to packet entity id of event-packet
	# this is not thread safe, thus sync processed
	set {_entity} to entity with id {_id}
	kill {_entity}

Async Processing ​

This processing type should be used for heavy computation with the data of a packet. (Think anticheats analyzing movement packets)

applescript
on clientbound entity velocity async processed:
    # ... heavy computation ...

DANGER

Minecraft is not thread safe, you can not access most of paper's API on the netty threads. If you want to access paper's API, you must switch back to the main thread. Look into Run Task (SkBee) Run Section (Skript-Reflect).

Listening to All Packets ​

This is how you can listen to all packets sent or received by the server.

applescript
on any packet:
    # event-packet and event-player are retrievable
    # ... code ...

Listening to a Packet Type ​

In PacketEventsSK packet types are defined by 2 parts, the direction (serverbound or clientbound) and the packet name (e.g. entity metadata). You can find a list of all packet types on SkDocs Packet Type

Here's an example:

applescript
on clientbound entity metadata packet:
    # event-packet and event-player are retrievable
    # ... code ...

Listening Priority ​

There are 2 priorities when it comes to the on packet event: the bukkit event priority and the packet processing priority.

  • The bukkit event priority is the same as the one used in normal bukkit events and can be set with the with priority syntax element.
  • The PacketEvents priority is a separate priority that controls the listener priority within PacketEvents and can be set using the with packet priority syntax element.

Both have 6 levels: monitor, lowest, low, normal, high and highest.

The priority for events is from the perspective of who should have the last say on the result, so lowest gets called first then all the way to highest and then monitor goes last.

applescript
on any packet with packet priority monitor:
    # This will be the last listener to receive the packet 
    # and will only view the contents of the packet,
    # you won't be able to modify under a "monitor" packet priority