SakuraMC/patches/server/0013-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 58b602e550258c1062ee940bc46538dac95d8979..50c6647ef3755c3712bf095c14c820019d6318e1 100644
--- a/src/main/java/net/minecraft/network/syncher/SynchedEntityData.java
+++ b/src/main/java/net/minecraft/network/syncher/SynchedEntityData.java
@@ -39,6 +39,7 @@ public class SynchedEntityData {
     private static final int GROW_FACTOR = 8;
     private SynchedEntityData.DataItem<?>[] itemsArray = new SynchedEntityData.DataItem<?>[DEFAULT_ENTRY_COUNT];
     // Paper end - Perf: array backed synched entity data
+    private boolean isForeignDirty; // Slice
 
     public SynchedEntityData(Entity trackedEntity) {
         this.entity = trackedEntity;
@@ -165,6 +166,16 @@ 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())) {
@@ -174,6 +185,12 @@ 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
@@ -183,6 +200,12 @@ public class SynchedEntityData {
     }
     // CraftBukkit end
 
+    // Slice start
+    public boolean isForeignDirty() {
+        return this.isForeignDirty;
+    }
+    // Slice end
+
     public boolean isDirty() {
         return this.isDirty;
     }
@@ -215,6 +238,29 @@ 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;
@@ -339,11 +385,14 @@ 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() {
@@ -370,6 +419,35 @@ 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 cce8f45c15b9a9acfbf9b769f7670cfd0969d62f..4237442c649845ffb0ff613e6c76ca478191e950 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.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;
 
@@ -401,11 +401,23 @@ public class ServerEntity {
     }
     
     // Sakura start - visibility api
-    private void broadcastEntityData(List<SynchedEntityData.DataValue<?>> packedValues) {
+    private void broadcastEntityData(SynchedEntityData datawatcher, List<SynchedEntityData.DataValue<?>> packedValues) {
         Packet<?> packet0 = new ClientboundSetEntityDataPacket(this.entity.getId(), packedValues);
         Packet<?> packet1 = null;
 
-        if (this.entity.isPrimedTNT) {
+        // Slice start
+        if (this.entity instanceof ServerPlayer serverPlayer) {
+            serverPlayer.connection.send(packet0);
+        }
+
+        packedValues = datawatcher.packForeignDirty(packedValues);
+
+        if (packedValues != null) {
+            packet0 = new ClientboundSetEntityDataPacket(this.entity.getId(), packedValues);
+        }
+
+        if (packedValues != null && this.entity.isPrimedTNT) {
+            // Slice end
             var copyOfDirtyItems = Lists.newArrayList(packedValues);
             copyOfDirtyItems.removeIf((data) -> data.id() == 8);
 
@@ -432,7 +444,7 @@ public class ServerEntity {
 
         if (list != null) {
             this.trackedDataValues = datawatcher.getNonDefaultValues();
-            this.broadcastEntityData(list); // Sakura - visibility api
+            this.broadcastEntityData(datawatcher, list); // Sakura - visibility api
         }
 
         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 9ee8a871714167c9b71c926a8ad41e0e6bb2d4e3..72b1fba4430cb2063b5305ee28758dffed272b8a 100644
--- a/src/main/java/net/minecraft/world/entity/Entity.java
+++ b/src/main/java/net/minecraft/world/entity/Entity.java
@@ -3418,7 +3418,7 @@ public abstract class Entity implements Nameable, EntityAccess, CommandSource, S
             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 1b8c7da956f43f1bebb3ad73d66a22a55fb0e3f5..b8687b3c6386288609cfb1980da2ee727acae03e 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 7a5ea7e0ea063eb0355dea89746a0e581548d131..90f10473ae441d68333cd497c718a3c982544533 100644
--- a/src/main/java/net/minecraft/world/entity/item/PrimedTnt.java
+++ b/src/main/java/net/minecraft/world/entity/item/PrimedTnt.java
@@ -189,7 +189,7 @@ 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 567704f61034363e48ef2a5b5566ebdc91682297..74dcfabdc66ef289b8d6a5c6606579b5321af1db 100644
--- a/src/main/java/net/minecraft/world/entity/player/Player.java
+++ b/src/main/java/net/minecraft/world/entity/player/Player.java
@@ -646,7 +646,7 @@ 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) {