Implement pre via version injection support for spigot module

[ytnoos]

Since Retrooper gave us the opportunity to possibly accept the pre-via patch, here we are. I merged my patch with the fixes [1] [2] made by @Axionize, whom I thank very much for contributing and making this possible. Currently, an old version of this patch is used by both Grim and LPX.

By default, PacketEvents keeps the standard post-Via behavior.
Pre-Via support is enabled dynamically when a Pre-Via listener is registered: in order to do that just override isPreVia() in your listener:

@Override
public boolean isPreVia() {
    return true;
}

I apologize in advance for any errors and look forward to hearing from you if any changes or improvements to the code are needed.

[SpigotRCE]

Damn

[3add]

W

[florianreuth]

Pure ViaVersion evilness:tm:

[booky10]

Hm, I'm not quite sure whether it is a good idea to lock this behavior behind a setting - would it be possible to dynamically inject our handlers if someone wants to register a pre-via listener?

[ytnoos]

Hm, I'm not quite sure whether it is a good idea to lock this behavior behind a setting - would it be possible to dynamically inject our handlers if someone wants to register a pre-via listener?

Injection is mostly done during PacketEvents init, and since anyone can register listeners at any time, it would mean that in order to do it correctly, we would reinject server channel and all connected players the first time a pre-via listener is registered. I think it can be done but the possibility of creating new problems increases. Is it worth it?

[booky10]

The problem with settings is that they are shared globally across all plugins using packetevents (except when you're shading)
If some random plugin decides they want to disable pre-via injection, this affects all other plugins using packetevents and may lead to unexpected behavior

I can take a look at dynamic injection later

[retrooper]

After some thought, dynamic injection may actually be the smartest option here. Based on the type of listener the developer(s) register, a handler (pre or post ViaVersion) will be added to the pipeline (dynamically). If developers register both, then we will have two handlers for incoming packets and two for outgoing. I think this is actually a decent solution, the only issue is PacketEvents has an internal listener which, by default, listens post ViaVersion. So on PE installations, the post ViaVersion handler would always be there no matter what.

[ytnoos]

I haven't tested this yet, let me know if the logic is fine. I couldn't find any other way to actually intercept registered listeners without exposing methods to EventManager that anyone could call

[NikV2]

Looking forward towards this pull request!

[ytnoos]

Tested on 1.8.8 and 1.21.8 and works well!

[retrooper]

I suppose we can start reviewing and editing this PR. I have not received any PR from Axionize, a Grim maintainer.

[retrooper]

So far, I've not been able to reach a resolution with the Grim team. I can start reviewing this PR starting on April 20th; feel free to send me reminders around that time. If possible, could you resolve the conflicts? @ytnoos

[ytnoos]

Don't review it yet. I'm still testing a few new things

[Dg32z]

[17:31:19 INFO]: [packetevents] Failed to map the Packet ID 334 to a PacketType constant. Bound: CLIENT, Connection state: LOGIN, Server version: 1.20.4
[17:31:19 INFO]: [packetevents] Disconnected Dg32z_ due to an invalid packet!
[17:31:19 INFO]: Dg32z_ lost connection: Invalid packet

It seems that support for some server versions has been broken

[ytnoos]

[17:31:19 INFO]: [packetevents] Failed to map the Packet ID 334 to a PacketType constant. Bound: CLIENT, Connection state: LOGIN, Server version: 1.20.4 [17:31:19 INFO]: [packetevents] Disconnected Dg32z_ due to an invalid packet! [17:31:19 INFO]: Dg32z_ lost connection: Invalid packet

It seems that support for some server versions has been broken

Can you tell me client version and plugin list?

[Dg32z]

[17:31:19 INFO]: [packetevents] Failed to map the Packet ID 334 to a PacketType constant. Bound: CLIENT, Connection state: LOGIN, Server version: 1.20.4 [17:31:19 INFO]: [packetevents] Disconnected Dg32z_ due to an invalid packet! [17:31:19 INFO]: Dg32z_ lost connection: Invalid packet
It seems that support for some server versions has been broken

Can you tell me client version and plugin list?

pl
[19:34:11 INFO]: Server Plugins (13):
[19:34:11 INFO]: Paper Plugins:
[19:34:11 INFO]: - PlugManX
[19:34:11 INFO]: Bukkit Plugins:
[19:34:11 INFO]: - CHAOS-BadWordFilter, Citizens, FastAsyncWorldEdit, LPX, LuckPerms, packetevents, PlaceholderAPI, spark, TAB, ViaBackwards
[19:34:11 INFO]: ViaRewind, ViaVersion
[19:34:12 INFO]: This server is running Paper version git-Paper-499 (MC: 1.20.4) (Implementing API version 1.20.4-R0.1-SNAPSHOT) (Git: 9de3f75 on ver/1.20.4)
You are running the latest version
Previous version: 1.21.8-60-29c8822 (MC: 1.21.8)
[19:34:23 INFO]: UUID of player Dg32z_ is b2707b1a-668e-36d2-ac98-782173baa7b8
[19:34:23 INFO]: [packetevents] Failed to map the Packet ID 39465 to a PacketType constant. Bound: CLIENT, Connection state: LOGIN, Server version: 1.20.4
[19:34:23 INFO]: [packetevents] Disconnected null due to an invalid packet!
[19:34:23 INFO]: com.mojang.authlib.GameProfile@2b09b26[id=b2707b1a-668e-36d2-ac98-782173baa7b8,name=Dg32z_,properties={}] lost connection: Disconnected, while in configuration phase null
plugman unload
[19:34:26 INFO]: [PlugMan] You must specify a plugin.
[19:34:26 INFO]: - Command: Unload
[19:34:26 INFO]: - Description: Unload a plugin.
[19:34:26 INFO]: - Usage: plugman
ver
[19:34:27 INFO]: This server is running Paper version git-Paper-499 (MC: 1.20.4) (Implementing API version 1.20.4-R0.1-SNAPSHOT) (Git: 9de3f75 on ver/1.20.4)
You are running the latest version
Previous version: 1.21.8-60-29c8822 (MC: 1.21.8)

[Dg32z]

[17:31:19 INFO]: [packetevents] Failed to map the Packet ID 334 to a PacketType constant. Bound: CLIENT, Connection state: LOGIN, Server version: 1.20.4 [17:31:19 INFO]: [packetevents] Disconnected Dg32z_ due to an invalid packet! [17:31:19 INFO]: Dg32z_ lost connection: Invalid packet
It seems that support for some server versions has been broken

Can you tell me client version and plugin list?

ClientVersion: 1.20.4
It seems like this issue occurs in 1.20x server versions

[ytnoos]

@Dg32z try this version, apparently the encoder was not in the right spot compared to the compression.

I also fixed the fact that the PreViaInternalListener was always forcing packetevents to inject pre-via handlers.

[Dg32z]

@Dg32z try this version, apparently the encoder was not in the right spot compared to the compression.

I also fixed the fact that the PreViaInternalListener was always forcing packetevents to inject pre-via handlers.

seem fixed
I tested it on 1.20.4 and 1.8.8, and it works well