From f08a412db57f65795e3a23ea9923c268ef55df4c Mon Sep 17 00:00:00 2001
From: EnZaXD <florian.michael07@gmail.com>
Date: Thu, 31 Oct 2024 10:22:57 +0100
Subject: [PATCH] Drop idle packets where only horizontal collision changed in
 1.21->1.21.2 (#4220)

---
 .../v1_21to1_21_2/Protocol1_21To1_21_2.java   |  2 +
 .../rewriter/EntityPacketRewriter1_21_2.java  | 27 +++++++++---
 .../storage/GroundFlagTracker.java            | 43 +++++++++++++++++++
 3 files changed, 66 insertions(+), 6 deletions(-)
 create mode 100644 common/src/main/java/com/viaversion/viaversion/protocols/v1_21to1_21_2/storage/GroundFlagTracker.java

diff --git a/common/src/main/java/com/viaversion/viaversion/protocols/v1_21to1_21_2/Protocol1_21To1_21_2.java b/common/src/main/java/com/viaversion/viaversion/protocols/v1_21to1_21_2/Protocol1_21To1_21_2.java
index 89508784d..bd2296787 100644
--- a/common/src/main/java/com/viaversion/viaversion/protocols/v1_21to1_21_2/Protocol1_21To1_21_2.java
+++ b/common/src/main/java/com/viaversion/viaversion/protocols/v1_21to1_21_2/Protocol1_21To1_21_2.java
@@ -49,6 +49,7 @@ import com.viaversion.viaversion.protocols.v1_21to1_21_2.rewriter.ParticleRewrit
 import com.viaversion.viaversion.protocols.v1_21to1_21_2.storage.BundleStateTracker;
 import com.viaversion.viaversion.protocols.v1_21to1_21_2.storage.ChunkLoadTracker;
 import com.viaversion.viaversion.protocols.v1_21to1_21_2.storage.EntityTracker1_21_2;
+import com.viaversion.viaversion.protocols.v1_21to1_21_2.storage.GroundFlagTracker;
 import com.viaversion.viaversion.protocols.v1_21to1_21_2.storage.PlayerPositionStorage;
 import com.viaversion.viaversion.rewriter.AttributeRewriter;
 import com.viaversion.viaversion.rewriter.SoundRewriter;
@@ -234,6 +235,7 @@ public final class Protocol1_21To1_21_2 extends AbstractProtocol<ClientboundPack
         connection.put(new BundleStateTracker());
         connection.put(new PlayerPositionStorage());
         connection.put(new ChunkLoadTracker());
+        connection.put(new GroundFlagTracker());
     }
 
     @Override
diff --git a/common/src/main/java/com/viaversion/viaversion/protocols/v1_21to1_21_2/rewriter/EntityPacketRewriter1_21_2.java b/common/src/main/java/com/viaversion/viaversion/protocols/v1_21to1_21_2/rewriter/EntityPacketRewriter1_21_2.java
index 8de0551dc..2638a44ff 100644
--- a/common/src/main/java/com/viaversion/viaversion/protocols/v1_21to1_21_2/rewriter/EntityPacketRewriter1_21_2.java
+++ b/common/src/main/java/com/viaversion/viaversion/protocols/v1_21to1_21_2/rewriter/EntityPacketRewriter1_21_2.java
@@ -40,6 +40,7 @@ import com.viaversion.viaversion.protocols.v1_21to1_21_2.storage.BundleStateTrac
 import com.viaversion.viaversion.protocols.v1_21to1_21_2.storage.ChunkLoadTracker;
 import com.viaversion.viaversion.protocols.v1_21to1_21_2.storage.ClientVehicleStorage;
 import com.viaversion.viaversion.protocols.v1_21to1_21_2.storage.EntityTracker1_21_2;
+import com.viaversion.viaversion.protocols.v1_21to1_21_2.storage.GroundFlagTracker;
 import com.viaversion.viaversion.protocols.v1_21to1_21_2.storage.PlayerPositionStorage;
 import com.viaversion.viaversion.rewriter.EntityRewriter;
 import com.viaversion.viaversion.rewriter.RegistryDataRewriter;
@@ -163,6 +164,7 @@ public final class EntityPacketRewriter1_21_2 extends EntityRewriter<Clientbound
 
             trackWorldDataByKey1_20_5(wrapper.user(), dimensionId, world);
 
+            wrapper.user().put(new GroundFlagTracker());
             wrapper.user().remove(ClientVehicleStorage.class);
         });
 
@@ -314,7 +316,7 @@ public final class EntityPacketRewriter1_21_2 extends EntityRewriter<Clientbound
             wrapper.passthrough(Types.DOUBLE); // X
             wrapper.passthrough(Types.DOUBLE); // Y
             wrapper.passthrough(Types.DOUBLE); // Z
-            readOnGround(wrapper);
+            handleOnGround(wrapper);
         });
         protocol.registerServerbound(ServerboundPackets1_21_2.MOVE_PLAYER_POS_ROT, wrapper -> {
             final double x = wrapper.passthrough(Types.DOUBLE); // X
@@ -322,7 +324,7 @@ public final class EntityPacketRewriter1_21_2 extends EntityRewriter<Clientbound
             final double z = wrapper.passthrough(Types.DOUBLE); // Z
             final float yaw = wrapper.passthrough(Types.FLOAT); // Yaw
             final float pitch = wrapper.passthrough(Types.FLOAT); // Pitch
-            readOnGround(wrapper);
+            handleOnGround(wrapper);
 
             final PlayerPositionStorage playerPositionStorage = wrapper.user().get(PlayerPositionStorage.class);
             if (playerPositionStorage.checkCaptureNextPlayerPositionPacket()) {
@@ -335,9 +337,19 @@ public final class EntityPacketRewriter1_21_2 extends EntityRewriter<Clientbound
         protocol.registerServerbound(ServerboundPackets1_21_2.MOVE_PLAYER_ROT, wrapper -> {
             wrapper.passthrough(Types.FLOAT); // Yaw
             wrapper.passthrough(Types.FLOAT); // Pitch
-            readOnGround(wrapper);
+            handleOnGround(wrapper);
+        });
+        protocol.registerServerbound(ServerboundPackets1_21_2.MOVE_PLAYER_STATUS_ONLY, wrapper -> {
+            final GroundFlagTracker tracker = wrapper.user().get(GroundFlagTracker.class);
+            final boolean prevOnGround = tracker.onGround();
+            final boolean prevHorizontalCollision = tracker.horizontalCollision();
+
+            handleOnGround(wrapper);
+            if (prevOnGround == tracker.onGround() && prevHorizontalCollision != tracker.horizontalCollision()) {
+                // Newer clients will send idle packets even though the on ground state didn't change, ignore them
+                wrapper.cancel();
+            }
         });
-        protocol.registerServerbound(ServerboundPackets1_21_2.MOVE_PLAYER_STATUS_ONLY, this::readOnGround);
         protocol.registerServerbound(ServerboundPackets1_21_2.ACCEPT_TELEPORTATION, wrapper -> {
             final PlayerPositionStorage playerPositionStorage = wrapper.user().get(PlayerPositionStorage.class);
             if (playerPositionStorage.checkHasPlayerPosition()) {
@@ -370,9 +382,12 @@ public final class EntityPacketRewriter1_21_2 extends EntityRewriter<Clientbound
         return registryDataRewriter;
     }
 
-    private void readOnGround(final PacketWrapper wrapper) {
+    private void handleOnGround(final PacketWrapper wrapper) {
+        final GroundFlagTracker tracker = wrapper.user().get(GroundFlagTracker.class);
+
         final short data = wrapper.read(Types.UNSIGNED_BYTE);
-        wrapper.write(Types.BOOLEAN, (data & 1) != 0); // On ground, ignoring horizontal collision data
+        wrapper.write(Types.BOOLEAN, tracker.setOnGround((data & 1) != 0)); // Ignoring horizontal collision data
+        tracker.setHorizontalCollision((data & 2) != 0);
     }
 
     private void storeEntityPositionRotation(final PacketWrapper wrapper, final boolean position, final boolean rotation) {
diff --git a/common/src/main/java/com/viaversion/viaversion/protocols/v1_21to1_21_2/storage/GroundFlagTracker.java b/common/src/main/java/com/viaversion/viaversion/protocols/v1_21to1_21_2/storage/GroundFlagTracker.java
new file mode 100644
index 000000000..0d44d8829
--- /dev/null
+++ b/common/src/main/java/com/viaversion/viaversion/protocols/v1_21to1_21_2/storage/GroundFlagTracker.java
@@ -0,0 +1,43 @@
+/*
+ * This file is part of ViaVersion - https://github.com/ViaVersion/ViaVersion
+ * Copyright (C) 2016-2024 ViaVersion and contributors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+package com.viaversion.viaversion.protocols.v1_21to1_21_2.storage;
+
+import com.viaversion.viaversion.api.connection.StorableObject;
+
+public final class GroundFlagTracker implements StorableObject {
+
+    private boolean onGround;
+    private boolean horizontalCollision;
+
+    public boolean onGround() {
+        return this.onGround;
+    }
+
+    public boolean setOnGround(boolean onGround) {
+        return this.onGround = onGround;
+    }
+
+    public boolean horizontalCollision() {
+        return this.horizontalCollision;
+    }
+
+    public void setHorizontalCollision(boolean horizontalCollision) {
+        this.horizontalCollision = horizontalCollision;
+    }
+
+}