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 37e193f57938047c8b886ed7d2816411392f94b4..6ca522b4a56eb210e15c914d13615ef497b33626 100644
--- a/src/main/java/net/minecraft/network/syncher/SynchedEntityData.java
+++ b/src/main/java/net/minecraft/network/syncher/SynchedEntityData.java
@@ -34,6 +34,7 @@ public class SynchedEntityData {
     private final Int2ObjectMap<SynchedEntityData.DataItem<?>> itemsById = new Int2ObjectOpenHashMap();
     // private final ReadWriteLock lock = new ReentrantReadWriteLock(); // Spigot - not required
     private boolean isDirty;
+    private boolean isForeignDirty; // Slice
 
     public SynchedEntityData(Entity trackedEntity) {
         this.entity = trackedEntity;
@@ -135,6 +136,12 @@ public class SynchedEntityData {
     }
 
     public <T> void set(EntityDataAccessor<T> key, T value) {
+        // Slice start
+        this.set(key, value, null);
+    }
+
+    public <T> void set(EntityDataAccessor<T> key, T value, T foreignValue) {
+        // Slice end
         SynchedEntityData.DataItem<T> datawatcher_item = this.getItem(key);
 
         if (ObjectUtils.notEqual(value, datawatcher_item.getValue())) {
@@ -144,6 +151,12 @@ 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
@@ -153,6 +166,12 @@ public class SynchedEntityData {
     }
     // CraftBukkit end
 
+    // Slice start
+    public boolean isForeignDirty() {
+        return this.isForeignDirty;
+    }
+    // Slice end
+
     public boolean isDirty() {
         return this.isDirty;
     }
@@ -185,6 +204,29 @@ public class SynchedEntityData {
         return list;
     }
 
+    // Slice start
+    @Nullable
+    public List<SynchedEntityData.DataValue<?>> packForeignDirty(List<DataValue<?>> unpackedData) {
+        List<SynchedEntityData.DataValue<?>> list = null;
+
+        for (DataValue<?> dataItem : unpackedData) {
+            DataItem<?> item = itemsById.get(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;
@@ -291,11 +333,14 @@ 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() {
@@ -322,6 +367,35 @@ 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 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 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.getSerializer().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 190e9761087baec5827d722a8281f0ffb6798341..18676547ee697bea691c0ee69df5906455c5f238 100644
--- a/src/main/java/net/minecraft/server/level/ServerEntity.java
+++ b/src/main/java/net/minecraft/server/level/ServerEntity.java
@@ -129,7 +129,7 @@ public class ServerEntity {
             }
         }
 
-        if (this.tickCount % this.updateInterval == 0 || this.entity.hasImpulse || this.entity.getEntityData().isDirty()) {
+        if (this.tickCount % this.updateInterval == 0 || this.entity.hasImpulse || this.entity.getEntityData().isForeignDirty()) { // Slice
             int i;
             int j;
 
@@ -367,7 +367,15 @@ 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 c0fb35497cfab69e5d28a70a2756f0d74a406630..35c4253e1ee951c31958bb9275a4f497fd5b16bb 100644
--- a/src/main/java/net/minecraft/world/entity/Entity.java
+++ b/src/main/java/net/minecraft/world/entity/Entity.java
@@ -3131,7 +3131,7 @@ public abstract class Entity implements Nameable, EntityAccess, CommandSource {
             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 3559457024f5c9bef4c44a27514e338c7d2b4172..6b85eecde57a809391d531bb11d189d0a25ccfdc 100644
--- a/src/main/java/net/minecraft/world/entity/item/FallingBlockEntity.java
+++ b/src/main/java/net/minecraft/world/entity/item/FallingBlockEntity.java
@@ -107,7 +107,7 @@ 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 5761b786f036df1516189edd67ea4439d64c6ea8..c2f04fca63ebef48a3092b60c703277abcb9b586 100644
--- a/src/main/java/net/minecraft/world/entity/item/PrimedTnt.java
+++ b/src/main/java/net/minecraft/world/entity/item/PrimedTnt.java
@@ -171,7 +171,7 @@ public class PrimedTnt extends Entity {
     }
 
     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 1116116e4ba6c5ecec400cd371b70b9e14efd92b..407401198c21dd5887aa3b7d86cdb112ef369007 100644
--- a/src/main/java/net/minecraft/world/entity/player/Player.java
+++ b/src/main/java/net/minecraft/world/entity/player/Player.java
@@ -637,7 +637,7 @@ 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) {