Scissors/patches/server/0028-Block-server-side-chunkbans.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Telesphoreo <me@telesphoreo.me>
Date: Thu, 8 Jun 2023 19:41:10 -0500
Subject: [PATCH] Block server side chunkbans


diff --git a/src/main/java/net/minecraft/network/PacketEncoder.java b/src/main/java/net/minecraft/network/PacketEncoder.java
index fbfadeb83719b81f42724e79c59e92ed88fdece7..bcb9d99359fb3e03c86d7429d9bcfe63b6c0f5d5 100644
--- a/src/main/java/net/minecraft/network/PacketEncoder.java
+++ b/src/main/java/net/minecraft/network/PacketEncoder.java
@@ -6,9 +6,18 @@ import io.netty.channel.ChannelHandlerContext;
 import io.netty.handler.codec.MessageToByteEncoder;
 import io.papermc.paper.adventure.PaperAdventure; // Paper
 import java.io.IOException;
+import java.util.Collections;
+
+import net.minecraft.ChatFormatting;
+import net.minecraft.core.NonNullList;
+import net.minecraft.nbt.CompoundTag;
+import net.minecraft.network.chat.Component;
+import net.minecraft.network.chat.SignedMessageBody;
 import net.minecraft.network.protocol.Packet;
 import net.minecraft.network.protocol.PacketFlow;
+import net.minecraft.network.protocol.game.*;
 import net.minecraft.util.profiling.jfr.JvmProfiler;
+import net.minecraft.world.item.ItemStack;
 import org.slf4j.Logger;
 
 public class PacketEncoder extends MessageToByteEncoder<Packet<?>> {
@@ -19,6 +28,23 @@ public class PacketEncoder extends MessageToByteEncoder<Packet<?>> {
         this.flow = side;
     }
 
+    // Scissors start
+    private static int tryWrite(Packet packet, FriendlyByteBuf friendlyByteBuf, ChannelHandlerContext channelHandlerContext, int i) {
+        friendlyByteBuf.writeVarInt(i);
+        friendlyByteBuf.adventure$locale = channelHandlerContext.channel().attr(PaperAdventure.LOCALE_ATTRIBUTE).get();
+
+        int j = friendlyByteBuf.writerIndex();
+        packet.write(friendlyByteBuf);
+        int k = friendlyByteBuf.writerIndex() - j;
+        int packetLength = friendlyByteBuf.readableBytes();
+        if (k > 8388608 || packetLength > MAX_PACKET_SIZE) {
+            throw new SkipPacketException(new IllegalArgumentException("Packet too big (is " + k + "): " + packet));
+        }
+
+        return k;
+    }
+    // Scissors end
+
     protected void encode(ChannelHandlerContext channelHandlerContext, Packet<?> packet, ByteBuf byteBuf) throws Exception {
         ConnectionProtocol connectionProtocol = channelHandlerContext.channel().attr(Connection.ATTRIBUTE_PROTOCOL).get();
         if (connectionProtocol == null) {
@@ -33,38 +59,66 @@ public class PacketEncoder extends MessageToByteEncoder<Packet<?>> {
                 throw new IOException("Can't serialize unregistered packet");
             } else {
                 FriendlyByteBuf friendlyByteBuf = new FriendlyByteBuf(byteBuf);
-                friendlyByteBuf.writeVarInt(i);
-                friendlyByteBuf.adventure$locale = channelHandlerContext.channel().attr(PaperAdventure.LOCALE_ATTRIBUTE).get(); // Paper
 
+                // Scissors start
+                int k;
                 try {
-                    int j = friendlyByteBuf.writerIndex();
-                    packet.write(friendlyByteBuf);
-                    int k = friendlyByteBuf.writerIndex() - j;
-                    if (false && k > 8388608) { // Paper - disable
-                        throw new IllegalArgumentException("Packet too big (is " + k + ", should be less than 8388608): " + packet);
-                    } else {
-                        int l = channelHandlerContext.channel().attr(Connection.ATTRIBUTE_PROTOCOL).get().getId();
-                        JvmProfiler.INSTANCE.onPacketSent(l, i, channelHandlerContext.channel().remoteAddress(), k);
-                    }
+                    k = tryWrite(packet, friendlyByteBuf, channelHandlerContext, i);
                 } catch (Throwable var10) {
-                    LOGGER.error("Packet encoding of packet ID {} threw (skippable? {})", i, packet.isSkippable(), var10); // Paper - Give proper error message
-                    if (packet.isSkippable()) {
-                        throw new SkipPacketException(var10);
-                    } else {
-                        throw var10;
+                    packet = capPacket(packet, i);
+                    if (packet == null) {
+                        throw new SkipPacketException(new IllegalArgumentException("Packet too big: " + packet));
                     }
+                    friendlyByteBuf.clear();
+                    k = tryWrite(packet, friendlyByteBuf, channelHandlerContext, i);
                 }
 
-                // Paper start
-                int packetLength = friendlyByteBuf.readableBytes();
-                if (packetLength > MAX_PACKET_SIZE) {
-                    throw new PacketTooLargeException(packet, packetLength);
-                }
-                // Paper end
+                int l = channelHandlerContext.channel().attr(Connection.ATTRIBUTE_PROTOCOL).get().getId();
+                JvmProfiler.INSTANCE.onPacketSent(l, i, channelHandlerContext.channel().remoteAddress(), k);
+                // Scissors end
             }
         }
     }
 
+    // Scissors start
+    private static Packet capPacket(Packet packet, int i) {
+        if (packet instanceof ClientboundBlockEntityDataPacket blockEntityDataPacket) {
+            packet = new ClientboundBlockEntityDataPacket(blockEntityDataPacket.getPos(), blockEntityDataPacket.getType(), new CompoundTag());
+        } else if (packet instanceof ClientboundLevelChunkPacketData chunkPacket) {
+            chunkPacket.clearNBT();
+        } else if (packet instanceof ClientboundSetEntityDataPacket) {
+            return null; // Skip
+        } else if (packet instanceof ClientboundContainerSetContentPacket containerSetContentPacket) {
+            packet = new ClientboundContainerSetContentPacket(containerSetContentPacket.getContainerId(), containerSetContentPacket.getStateId(), NonNullList.create(), ItemStack.EMPTY);
+        } else if (packet instanceof ClientboundSetEquipmentPacket setEquipmentPacket) {
+            packet = new ClientboundSetEquipmentPacket(setEquipmentPacket.getEntity(), Collections.emptyList());
+        } else if (packet instanceof ClientboundContainerSetSlotPacket containerSetSlotPacket) {
+            packet = new ClientboundContainerSetSlotPacket(containerSetSlotPacket.getContainerId(), containerSetSlotPacket.getStateId(), containerSetSlotPacket.getSlot(), ItemStack.EMPTY);
+        } else if (packet instanceof ClientboundMapItemDataPacket mapItemDataPacket) {
+            packet = new ClientboundMapItemDataPacket(mapItemDataPacket.getMapId(), mapItemDataPacket.getScale(), mapItemDataPacket.isLocked(), null, null);
+        } else if (packet instanceof ClientboundSystemChatPacket) {
+            return null;
+        } else if (packet instanceof ClientboundDisguisedChatPacket) {
+            return null;
+        } else if (packet instanceof ClientboundPlayerChatPacket playerChatPacket) {
+            final SignedMessageBody.Packed body = playerChatPacket.body();
+            packet = new ClientboundPlayerChatPacket(playerChatPacket.sender(), // Not sending this packet results in a kick when someone says something.
+                playerChatPacket.index(),
+                playerChatPacket.signature(),
+                playerChatPacket.body(),
+                Component.empty().append("** Message too large **").withStyle(ChatFormatting.RED),
+                playerChatPacket.filterMask(),
+                playerChatPacket.chatType()
+            );
+        } else {
+            LOGGER.error("Packet with ID {} was too large and was not caught. Please report this to the Scissors developers.", i);
+            return null;
+        }
+
+        return packet;
+    }
+    // Scissors end
+
     // Paper start
     private static int MAX_PACKET_SIZE = 8388608;
 
diff --git a/src/main/java/net/minecraft/network/protocol/game/ClientboundBlockEntityDataPacket.java b/src/main/java/net/minecraft/network/protocol/game/ClientboundBlockEntityDataPacket.java
index 3944852921335c78a04a9dc301882ab5b152b1ed..96ee53c7cc862e059328c5cdf5e07f309df6a79e 100644
--- a/src/main/java/net/minecraft/network/protocol/game/ClientboundBlockEntityDataPacket.java
+++ b/src/main/java/net/minecraft/network/protocol/game/ClientboundBlockEntityDataPacket.java
@@ -24,7 +24,7 @@ public class ClientboundBlockEntityDataPacket implements Packet<ClientGamePacket
         return create(blockEntity, BlockEntity::getUpdateTag);
     }
 
-    private ClientboundBlockEntityDataPacket(BlockPos pos, BlockEntityType<?> blockEntityType, CompoundTag nbt) {
+    public ClientboundBlockEntityDataPacket(BlockPos pos, BlockEntityType<?> blockEntityType, CompoundTag nbt) { // Scissors - private -> public
         this.pos = pos;
         this.type = blockEntityType;
         this.tag = nbt.isEmpty() ? null : nbt;
diff --git a/src/main/java/net/minecraft/network/protocol/game/ClientboundLevelChunkPacketData.java b/src/main/java/net/minecraft/network/protocol/game/ClientboundLevelChunkPacketData.java
index 39b879f21f958dbd91ab0f74e5d4f3c74928fc33..688287c637a0d4b28d630b7304a3c2cf339bdf54 100644
--- a/src/main/java/net/minecraft/network/protocol/game/ClientboundLevelChunkPacketData.java
+++ b/src/main/java/net/minecraft/network/protocol/game/ClientboundLevelChunkPacketData.java
@@ -33,6 +33,13 @@ public class ClientboundLevelChunkPacketData {
     }
     // Paper end
 
+    // Scissors start
+    public void clearNBT() {
+        this.blockEntitiesData.clear();
+        this.extraPackets.clear();
+    }
+    // Scissors end
+
     // Paper start - Anti-Xray - Add chunk packet info
     @Deprecated @io.papermc.paper.annotation.DoNotUse public ClientboundLevelChunkPacketData(LevelChunk chunk) { this(chunk, null); }
     public ClientboundLevelChunkPacketData(LevelChunk chunk, com.destroystokyo.paper.antixray.ChunkPacketInfo<net.minecraft.world.level.block.state.BlockState> chunkPacketInfo) {
@@ -58,6 +65,7 @@ public class ClientboundLevelChunkPacketData {
         int totalTileEntities = 0; // Paper
 
         for(Map.Entry<BlockPos, BlockEntity> entry2 : chunk.getBlockEntities().entrySet()) {
+            if (this.extraPackets.size() > 50) break; // Scissors - Limit extraPackets size
             // Paper start
             if (++totalTileEntities > TE_LIMIT) {
                 var packet = entry2.getValue().getUpdatePacket();