From 067c93a63a375fb2eb48fd99d147297a31e6f62b Mon Sep 17 00:00:00 2001
From: Nassim Jahnke <jahnke.nassim@gmail.com>
Date: Sat, 25 Sep 2021 10:11:43 +0200
Subject: [PATCH] Cancel null block entity nbt updates

---
 .../packets/BlockItemPackets1_16_2.java       | 19 ++++++-------------
 .../packets/BlockItemPackets1_18.java         |  9 ++++++++-
 2 files changed, 14 insertions(+), 14 deletions(-)

diff --git a/common/src/main/java/com/viaversion/viabackwards/protocol/protocol1_16_1to1_16_2/packets/BlockItemPackets1_16_2.java b/common/src/main/java/com/viaversion/viabackwards/protocol/protocol1_16_1to1_16_2/packets/BlockItemPackets1_16_2.java
index f3dd8e42..e290c1cb 100644
--- a/common/src/main/java/com/viaversion/viabackwards/protocol/protocol1_16_1to1_16_2/packets/BlockItemPackets1_16_2.java
+++ b/common/src/main/java/com/viaversion/viabackwards/protocol/protocol1_16_1to1_16_2/packets/BlockItemPackets1_16_2.java
@@ -21,14 +21,12 @@ import com.viaversion.viabackwards.api.rewriters.TranslatableRewriter;
 import com.viaversion.viabackwards.protocol.protocol1_16_1to1_16_2.Protocol1_16_1To1_16_2;
 import com.viaversion.viaversion.api.minecraft.BlockChangeRecord;
 import com.viaversion.viaversion.api.minecraft.BlockChangeRecord1_8;
-import com.viaversion.viaversion.api.minecraft.Position;
 import com.viaversion.viaversion.api.minecraft.chunks.Chunk;
 import com.viaversion.viaversion.api.minecraft.chunks.ChunkSection;
 import com.viaversion.viaversion.api.protocol.remapper.PacketRemapper;
 import com.viaversion.viaversion.api.type.Type;
 import com.viaversion.viaversion.libs.opennbt.tag.builtin.CompoundTag;
 import com.viaversion.viaversion.libs.opennbt.tag.builtin.IntArrayTag;
-import com.viaversion.viaversion.libs.opennbt.tag.builtin.IntTag;
 import com.viaversion.viaversion.libs.opennbt.tag.builtin.ListTag;
 import com.viaversion.viaversion.libs.opennbt.tag.builtin.StringTag;
 import com.viaversion.viaversion.libs.opennbt.tag.builtin.Tag;
@@ -98,13 +96,8 @@ public class BlockItemPackets1_16_2 extends com.viaversion.viabackwards.api.rewr
                     }
 
                     for (CompoundTag blockEntity : chunk.getBlockEntities()) {
-                        if (blockEntity == null) continue;
-
-                        IntTag x = blockEntity.get("x");
-                        IntTag y = blockEntity.get("y");
-                        IntTag z = blockEntity.get("z");
-                        if (x != null && y != null && z != null) {
-                            handleBlockEntity(blockEntity, new Position(x.asInt(), y.asShort(), z.asInt()));
+                        if (blockEntity != null) {
+                            handleBlockEntity(blockEntity);
                         }
                     }
                 });
@@ -114,10 +107,10 @@ public class BlockItemPackets1_16_2 extends com.viaversion.viabackwards.api.rewr
         protocol.registerClientbound(ClientboundPackets1_16_2.BLOCK_ENTITY_DATA, new PacketRemapper() {
             @Override
             public void registerMap() {
+                map(Type.POSITION1_14);
+                map(Type.UNSIGNED_BYTE);
                 handler(wrapper -> {
-                    Position position = wrapper.passthrough(Type.POSITION1_14);
-                    wrapper.passthrough(Type.UNSIGNED_BYTE);
-                    handleBlockEntity(wrapper.passthrough(Type.NBT), position);
+                    handleBlockEntity(wrapper.passthrough(Type.NBT));
                 });
             }
         });
@@ -161,7 +154,7 @@ public class BlockItemPackets1_16_2 extends com.viaversion.viabackwards.api.rewr
         });
     }
 
-    private void handleBlockEntity(CompoundTag tag, Position position) {
+    private void handleBlockEntity(CompoundTag tag) {
         StringTag idTag = tag.get("id");
         if (idTag == null) return;
         if (idTag.getValue().equals("minecraft:skull")) {
diff --git a/common/src/main/java/com/viaversion/viabackwards/protocol/protocol1_17_1to1_18/packets/BlockItemPackets1_18.java b/common/src/main/java/com/viaversion/viabackwards/protocol/protocol1_17_1to1_18/packets/BlockItemPackets1_18.java
index 3a89c90f..35a7ca1d 100644
--- a/common/src/main/java/com/viaversion/viabackwards/protocol/protocol1_17_1to1_18/packets/BlockItemPackets1_18.java
+++ b/common/src/main/java/com/viaversion/viabackwards/protocol/protocol1_17_1to1_18/packets/BlockItemPackets1_18.java
@@ -89,6 +89,13 @@ public final class BlockItemPackets1_18 extends ItemRewriter<Protocol1_17_1To1_1
                 map(Type.POSITION1_14);
                 handler(wrapper -> {
                     final int id = wrapper.read(Type.VAR_INT);
+                    final CompoundTag tag = wrapper.read(Type.NBT);
+                    if (tag == null) {
+                        // Cancel nbt-less updates (screw open commandblocks)
+                        wrapper.cancel();
+                        return;
+                    }
+
                     final int mappedId = BlockEntityIds.mappedId(id);
                     if (mappedId == -1) {
                         wrapper.cancel();
@@ -131,13 +138,13 @@ public final class BlockItemPackets1_18 extends ItemRewriter<Protocol1_17_1To1_1
 
                     final List<CompoundTag> blockEntityTags = new ArrayList<>(oldChunk.blockEntities().size());
                     for (final BlockEntity blockEntity : oldChunk.blockEntities()) {
-                        final CompoundTag tag = blockEntity.tag() != null ? blockEntity.tag() : new CompoundTag();
                         final String id = protocol.getMappingData().blockEntities().get(blockEntity.typeId());
                         if (id == null) {
                             // Shrug
                             continue;
                         }
 
+                        final CompoundTag tag = blockEntity.tag() != null ? blockEntity.tag() : new CompoundTag();
                         blockEntityTags.add(tag);
                         tag.put("x", new IntTag((oldChunk.getX() << 4) + blockEntity.sectionX()));
                         tag.put("y", new IntTag(blockEntity.y()));