SakuraMC/patches/server/0012-Slice-Packet-obfuscation-and-reduction.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Cryptite <cryptite@gmail.com>
Date: Wed, 6 Oct 2021 11:03:01 -0500
Subject: [PATCH] (Slice) Packet obfuscation and reduction

Minecraft is overzealous about packet updates for Entities. In Loka's case, we want to reduce as many unnecessary
packet updates as possible. This patch is likely to be updated over and over in terms of reducing packet sends.

In summary, this patch creates the concept of a "foreignValue" of a packet's data. We treat packets in two ways:
1) The packet sent to the player itself (the normal way). This always has all of the values as usual.
2) The packet data as seen by any other (foreign) players.

This patch adds the ability to set a "foreignValue" for an entity value so as to obfuscate data received by other players.
The current packets modified/obfuscated are the following:

    # This reduces the amount of health packet updates as well which is great for players in combat.

    # Air level packets are sent PER-TICK, and as such a player with any change in air level will only spam themselves
    # with packets instead of every single player within tracking distance

diff --git a/src/main/java/net/minecraft/network/syncher/SynchedEntityData.java b/src/main/java/net/minecraft/network/syncher/SynchedEntityData.java
index 0f99733660f91280e4c6262cf75b3c9cae86f65a..ba9f8fe6fafc54bbdfb104de28af4b392feb4483 100644
--- a/src/main/java/net/minecraft/network/syncher/SynchedEntityData.java
+++ b/src/main/java/net/minecraft/network/syncher/SynchedEntityData.java
@@ -22,6 +22,7 @@ public class SynchedEntityData {
     private final SyncedDataHolder entity;
     private final SynchedEntityData.DataItem<?>[] itemsById;
     private boolean isDirty;
+    private boolean isForeignDirty; // Slice
 
     SynchedEntityData(SyncedDataHolder trackedEntity, SynchedEntityData.DataItem<?>[] entries) {
         this.entity = trackedEntity;
@@ -63,6 +64,16 @@ public class SynchedEntityData {
     }
 
     public <T> void set(EntityDataAccessor<T> key, T value, boolean force) {
+        // Slice start
+        this.set(key, value, null, force);
+    }
+
+    public <T> void set(EntityDataAccessor<T> key, T value, T foreignValue) {
+        this.set(key, value, foreignValue, false);
+    }
+
+    public <T> void set(EntityDataAccessor<T> key, T value, T foreignValue, boolean force) {
+        // Slice end
         SynchedEntityData.DataItem<T> datawatcher_item = this.getItem(key);
 
         if (force || ObjectUtils.notEqual(value, datawatcher_item.getValue())) {
@@ -72,6 +83,12 @@ public class SynchedEntityData {
             this.isDirty = true;
         }
 
+        // Slice start
+        if (foreignValue != null && ObjectUtils.notEqual(foreignValue, datawatcher_item.getForeignValue())) {
+            datawatcher_item.setForeignValue(foreignValue);
+            this.isForeignDirty = true;
+        }
+        // Slice end
     }
 
     // CraftBukkit start - add method from above
@@ -81,6 +98,12 @@ public class SynchedEntityData {
     }
     // CraftBukkit end
 
+    // Slice start
+    public boolean isForeignDirty() {
+        return this.isForeignDirty;
+    }
+    // Slice end
+
     public boolean isDirty() {
         return this.isDirty;
     }
@@ -108,6 +131,29 @@ public class SynchedEntityData {
         }
     }
 
+    // Slice start
+    @Nullable
+    public List<SynchedEntityData.DataValue<?>> packForeignDirty(List<DataValue<?>> unpackedData) {
+        List<SynchedEntityData.DataValue<?>> list = null;
+
+        for (DataValue<?> dataItem : unpackedData) {
+            DataItem<?> item = this.itemsById[dataItem.id()];
+            if (item.isDirty(true)) {
+                item.setForeignDirty(false);
+
+                if (list == null) {
+                    list = new ArrayList<>();
+                }
+
+                list.add(item.copy(true));
+            }
+        }
+
+        this.isForeignDirty = false;
+        return list;
+    }
+    // Slice end
+
     @Nullable
     public List<SynchedEntityData.DataValue<?>> getNonDefaultValues() {
         List<SynchedEntityData.DataValue<?>> list = null;
@@ -171,11 +217,14 @@ public class SynchedEntityData {
         T value;
         private final T initialValue;
         private boolean dirty;
+        @Nullable T foreignValue = null; // Slice
+        private boolean foreignDirty; // Slice
 
         public DataItem(EntityDataAccessor<T> data, T value) {
             this.accessor = data;
             this.initialValue = value;
             this.value = value;
+            this.foreignDirty = true; // Slice
         }
 
         public EntityDataAccessor<T> getAccessor() {
@@ -202,6 +251,35 @@ public class SynchedEntityData {
             return this.initialValue.equals(this.value);
         }
 
+        // Slice start
+        public void setForeignValue(T foreignValue) {
+            this.foreignValue = foreignValue;
+            this.foreignDirty = true;
+        }
+
+        public @Nullable T getForeignValue() {
+            return this.foreignValue;
+        }
+
+        public boolean isDirty(boolean foreign) {
+            if (foreign) {
+                //There must be a foreign value in order for this to be dirty, otherwise we consider this a normal
+                //value and check the normal dirty flag.
+                return this.foreignValue == null || this.foreignDirty;
+            }
+
+            return this.dirty;
+        }
+
+        public void setForeignDirty(boolean dirty) {
+            this.foreignDirty = dirty;
+        }
+
+        public SynchedEntityData.DataValue<T> copy(boolean foreign) {
+            return SynchedEntityData.DataValue.create(this.accessor, this.accessor.serializer().copy((foreign && this.foreignValue != null ? this.foreignValue : this.value)));
+        }
+        // Slice end
+
         public SynchedEntityData.DataValue<T> value() {
             return SynchedEntityData.DataValue.create(this.accessor, this.value);
         }
diff --git a/src/main/java/net/minecraft/server/level/ServerEntity.java b/src/main/java/net/minecraft/server/level/ServerEntity.java
index a2279262c93408c11f5d2290b48fd794975e8cfe..09975c9be245207281b616f77c768aa048b0c140 100644
--- a/src/main/java/net/minecraft/server/level/ServerEntity.java
+++ b/src/main/java/net/minecraft/server/level/ServerEntity.java
@@ -148,7 +148,7 @@ public class ServerEntity {
             }
         }
 
-        if (this.forceStateResync || this.tickCount % this.updateInterval == 0 || this.entity.hasImpulse || this.entity.getEntityData().isDirty()) { // Paper - fix desync when a player is added to the tracker
+        if (this.forceStateResync || this.tickCount % this.updateInterval == 0 || this.entity.hasImpulse || this.entity.getEntityData().isForeignDirty()) { // Slice// Paper - fix desync when a player is added to the tracker
             int i;
             int j;
 
@@ -390,7 +390,15 @@ public class ServerEntity {
 
         if (list != null) {
             this.trackedDataValues = datawatcher.getNonDefaultValues();
-            this.broadcastAndSend(new ClientboundSetEntityDataPacket(this.entity.getId(), list));
+            // Slice start
+            if (!(this.entity instanceof ServerPlayer)) {
+                list = datawatcher.packForeignDirty(list);
+            }
+
+            if (list != null) {
+                this.broadcastAndSend(new ClientboundSetEntityDataPacket(this.entity.getId(), list));
+            }
+            // Slice end
         }
 
         if (this.entity instanceof LivingEntity) {
diff --git a/src/main/java/net/minecraft/world/entity/Entity.java b/src/main/java/net/minecraft/world/entity/Entity.java
index 88d01e59869f8e6c528fb3ae1485cd86a23cb383..6f330f99a80f291bce638b0769e5ed00c283ac78 100644
--- a/src/main/java/net/minecraft/world/entity/Entity.java
+++ b/src/main/java/net/minecraft/world/entity/Entity.java
@@ -3470,7 +3470,7 @@ public abstract class Entity implements SyncedDataHolder, Nameable, EntityAccess
             this.entityData.markDirty(Entity.DATA_AIR_SUPPLY_ID);
             return;
         }
-        this.entityData.set(Entity.DATA_AIR_SUPPLY_ID, event.getAmount());
+        this.entityData.set(Entity.DATA_AIR_SUPPLY_ID, event.getAmount(), getMaxAirSupply()); // Slice
         // CraftBukkit end
     }
 
diff --git a/src/main/java/net/minecraft/world/entity/item/FallingBlockEntity.java b/src/main/java/net/minecraft/world/entity/item/FallingBlockEntity.java
index b6a4753252b748c06a62b7faa6b05c1fb904d62e..86e12495ce807ba06210535350caa7db5e15d139 100644
--- a/src/main/java/net/minecraft/world/entity/item/FallingBlockEntity.java
+++ b/src/main/java/net/minecraft/world/entity/item/FallingBlockEntity.java
@@ -111,7 +111,7 @@ public class FallingBlockEntity extends Entity {
     }
 
     public void setStartPos(BlockPos pos) {
-        this.entityData.set(FallingBlockEntity.DATA_START_POS, pos);
+        this.entityData.set(FallingBlockEntity.DATA_START_POS, pos, BlockPos.ZERO); // Slice
     }
 
     public BlockPos getStartPos() {
diff --git a/src/main/java/net/minecraft/world/entity/item/PrimedTnt.java b/src/main/java/net/minecraft/world/entity/item/PrimedTnt.java
index 09f09a8fbf0eee62295001ce5b7ed5329445d2b0..16340c2f8a948136c9fe0b2314c9ec7cbee74937 100644
--- a/src/main/java/net/minecraft/world/entity/item/PrimedTnt.java
+++ b/src/main/java/net/minecraft/world/entity/item/PrimedTnt.java
@@ -182,7 +182,7 @@ public class PrimedTnt extends Entity implements TraceableEntity {
     }
 
     public void setFuse(int fuse) {
-        this.entityData.set(PrimedTnt.DATA_FUSE_ID, fuse);
+        this.entityData.set(PrimedTnt.DATA_FUSE_ID, fuse, (fuse / 10) * 10); // Slice
     }
 
     public int getFuse() {
diff --git a/src/main/java/net/minecraft/world/entity/player/Player.java b/src/main/java/net/minecraft/world/entity/player/Player.java
index 686374e89e41b0917791264f3281f7384835bca8..74130ccef989757b81507f084cc30a0e593ecaf3 100644
--- a/src/main/java/net/minecraft/world/entity/player/Player.java
+++ b/src/main/java/net/minecraft/world/entity/player/Player.java
@@ -645,7 +645,7 @@ public abstract class Player extends LivingEntity {
     public void increaseScore(int score) {
         int j = this.getScore();
 
-        this.entityData.set(Player.DATA_SCORE_ID, j + score);
+        this.entityData.set(Player.DATA_SCORE_ID, j + score, 0); // Slice
     }
 
     public void startAutoSpinAttack(int riptideTicks) {