windopper · March 14, 2022 11:55 · Mar 14, 2022
diff --git a/PacketListener.java b/PacketListener.java
@@ -0,0 +1,62 @@
+import io.netty.channel.*;
+import net.minecraft.network.protocol.game.PacketPlayInUseEntity;
+import org.bukkit.Bukkit;
+import org.bukkit.craftbukkit.v1_17_R1.entity.CraftPlayer;
+import org.bukkit.entity.Player;
+import org.bukkit.event.EventHandler;
+import org.bukkit.event.Listener;
+import org.bukkit.event.player.PlayerJoinEvent;
+import org.bukkit.event.player.PlayerQuitEvent;
+
+import java.lang.reflect.Field;
+
+public class PacketListener implements Listener {
+    @EventHandler
+    public void PlayerJoinEvent(PlayerJoinEvent event) {
+        Player player = event.getPlayer();
+        injectPlayer(player);
+    }
+    @EventHandler
+    public void PlayerQuitEvent(PlayerQuitEvent event) {
+        Player player = event.getPlayer();
+        removePlayer(player);
+    }
+    private void removePlayer(Player player) {
+        Channel channel = ((CraftPlayer) player).getHandle().b.a.k;
+        channel.eventLoop().submit(() -> {
+            channel.pipeline().remove(player.getName());
+            return null;
+        });
+    }
+
+    private void injectPlayer(Player player) {
+        ChannelDuplexHandler channelDuplexHandler = new ChannelDuplexHandler() {
+            @Override
+            public void channelRead(ChannelHandlerContext ctx, Object packet) throws Exception {
+                if(packet instanceof PacketPlayInUseEntity packetPlayInUseEntity) {
+                    int entityId = (int) getValue(packetPlayInUseEntity, "a");
+                    Bukkit.broadcastMessage("entityId : "+entityId);
+                }
+
+                super.channelRead(ctx, packet);
+            }
+        };
+
+        ChannelPipeline pipeline = ((CraftPlayer) player).getHandle().b.a.k.pipeline();
+        pipeline.addBefore("packet_handler", player.getName(), channelDuplexHandler);
+    }
+
+    private Object getValue(Object object, String fieldName) {
+        Object result = null;
+        try {
+            Field field = object.getClass().getDeclaredField(fieldName);
+            field.setAccessible(true);
+            result = field.get(object);
+            field.setAccessible(false);
+        }
+        catch(Exception e) {
+            e.printStackTrace();
+        }
+        return result;
+    }
+}