From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Nassim Jahnke <nassim@njahnke.dev>
Date: Wed, 1 Dec 2021 12:36:25 +0100
Subject: [PATCH] Prevent sending oversized item data in equipment and metadata

Co-authored-by: Jake Potrebic <jake.m.potrebic@gmail.com>

diff --git a/src/main/java/io/papermc/paper/util/DataSanitizationUtil.java b/src/main/java/io/papermc/paper/util/DataSanitizationUtil.java
new file mode 100644
index 0000000000000000000000000000000000000000..e9436f8a73ee0a02096d66e14d73edaae28d5a41
--- /dev/null
+++ b/src/main/java/io/papermc/paper/util/DataSanitizationUtil.java
@@ -0,0 +1,100 @@
+package io.papermc.paper.util;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.function.UnaryOperator;
+import net.minecraft.network.RegistryFriendlyByteBuf;
+import net.minecraft.network.codec.StreamCodec;
+import net.minecraft.world.item.ItemStack;
+import net.minecraft.world.item.Items;
+import net.minecraft.world.item.component.BundleContents;
+import net.minecraft.world.item.component.ChargedProjectiles;
+import net.minecraft.world.item.component.ItemContainerContents;
+import org.checkerframework.checker.nullness.qual.NonNull;
+import org.checkerframework.framework.qual.DefaultQualifier;
+
+@DefaultQualifier(NonNull.class)
+public final class DataSanitizationUtil {
+
+    private static final ThreadLocal<DataSanitizer> DATA_SANITIZER = ThreadLocal.withInitial(DataSanitizer::new);
+
+    public static DataSanitizer start(final boolean sanitize) {
+        final DataSanitizer sanitizer = DATA_SANITIZER.get();
+        if (sanitize) {
+            sanitizer.start();
+        }
+        return sanitizer;
+    }
+
+    public static final StreamCodec<RegistryFriendlyByteBuf, ChargedProjectiles> CHARGED_PROJECTILES = codec(ChargedProjectiles.STREAM_CODEC, DataSanitizationUtil::sanitizeChargedProjectiles);
+    public static final StreamCodec<RegistryFriendlyByteBuf, BundleContents> BUNDLE_CONTENTS = codec(BundleContents.STREAM_CODEC, DataSanitizationUtil::sanitizeBundleContents);
+    public static final StreamCodec<RegistryFriendlyByteBuf, ItemContainerContents> CONTAINER = codec(ItemContainerContents.STREAM_CODEC, contents -> ItemContainerContents.EMPTY);
+
+    private static ChargedProjectiles sanitizeChargedProjectiles(final ChargedProjectiles projectiles) {
+        if (projectiles.isEmpty()) {
+            return projectiles;
+        }
+        final List<ItemStack> items = projectiles.getItems();
+        final List<ItemStack> sanitized = new ArrayList<>();
+        for (int i = 0; i < Math.min(items.size(), 3); i++) {
+            // we want to preserve item type as vanilla client can change visuals based on type
+            sanitized.add(new ItemStack(items.get(i).getItemHolder()));
+        }
+        return ChargedProjectiles.of(sanitized);
+    }
+
+    private static BundleContents sanitizeBundleContents(final BundleContents contents) {
+        // Bundles change their texture based on their fullness.
+        int sizeUsed = 0;
+        for (final ItemStack item : contents.items()) {
+            final int scale = 64 / item.getMaxStackSize();
+            sizeUsed += scale * item.getCount();
+        }
+        // Now we add a single fake item that uses the same amount of slots as all other items.
+        final List<ItemStack> items = new ArrayList<>();
+        items.add(new ItemStack(Items.PAPER, sizeUsed));
+        return new BundleContents(items);
+    }
+
+    private static <B, A> StreamCodec<B, A> codec(final StreamCodec<B, A> delegate, final UnaryOperator<A> sanitizer) {
+        return new DataSanitizationCodec<>(delegate, sanitizer);
+    }
+
+    private record DataSanitizationCodec<B, A>(StreamCodec<B, A> delegate, UnaryOperator<A> sanitizer) implements StreamCodec<B, A> {
+
+        @Override
+        public @NonNull A decode(final @NonNull B buf) {
+            return this.delegate.decode(buf);
+        }
+
+        @Override
+        public void encode(final @NonNull B buf, final @NonNull A value) {
+            if (!DATA_SANITIZER.get().value().get()) {
+                this.delegate.encode(buf, value);
+            } else {
+                this.delegate.encode(buf, this.sanitizer.apply(value));
+            }
+        }
+    }
+
+    public record DataSanitizer(AtomicBoolean value) implements AutoCloseable {
+
+        public DataSanitizer() {
+            this(new AtomicBoolean(false));
+        }
+
+        public void start() {
+            this.value.compareAndSet(false, true);
+        }
+
+        @Override
+        public void close() {
+            this.value.compareAndSet(true, false);
+        }
+    }
+
+    private DataSanitizationUtil() {
+    }
+
+}
diff --git a/src/main/java/net/minecraft/core/component/DataComponents.java b/src/main/java/net/minecraft/core/component/DataComponents.java
index c9aef759c1485da753e820f9b509117ca50a31e4..60757f8df706cba92350d73503b73913cff3bcfc 100644
--- a/src/main/java/net/minecraft/core/component/DataComponents.java
+++ b/src/main/java/net/minecraft/core/component/DataComponents.java
@@ -138,10 +138,10 @@ public class DataComponents {
         "map_post_processing", builder -> builder.networkSynchronized(MapPostProcessing.STREAM_CODEC)
     );
     public static final DataComponentType<ChargedProjectiles> CHARGED_PROJECTILES = register(
-        "charged_projectiles", builder -> builder.persistent(ChargedProjectiles.CODEC).networkSynchronized(ChargedProjectiles.STREAM_CODEC).cacheEncoding()
+        "charged_projectiles", builder -> builder.persistent(ChargedProjectiles.CODEC).networkSynchronized(io.papermc.paper.util.DataSanitizationUtil.CHARGED_PROJECTILES).cacheEncoding() // Paper - sanitize charged projectiles
     );
     public static final DataComponentType<BundleContents> BUNDLE_CONTENTS = register(
-        "bundle_contents", builder -> builder.persistent(BundleContents.CODEC).networkSynchronized(BundleContents.STREAM_CODEC).cacheEncoding()
+        "bundle_contents", builder -> builder.persistent(BundleContents.CODEC).networkSynchronized(io.papermc.paper.util.DataSanitizationUtil.BUNDLE_CONTENTS).cacheEncoding() // Paper - sanitize bundle contents
     );
     public static final DataComponentType<PotionContents> POTION_CONTENTS = register(
         "potion_contents", builder -> builder.persistent(PotionContents.CODEC).networkSynchronized(PotionContents.STREAM_CODEC).cacheEncoding()
@@ -208,7 +208,7 @@ public class DataComponents {
         "pot_decorations", builder -> builder.persistent(PotDecorations.CODEC).networkSynchronized(PotDecorations.STREAM_CODEC).cacheEncoding()
     );
     public static final DataComponentType<ItemContainerContents> CONTAINER = register(
-        "container", builder -> builder.persistent(ItemContainerContents.CODEC).networkSynchronized(ItemContainerContents.STREAM_CODEC).cacheEncoding()
+        "container", builder -> builder.persistent(ItemContainerContents.CODEC).networkSynchronized(io.papermc.paper.util.DataSanitizationUtil.CONTAINER).cacheEncoding() // Paper - sanitize container contents
     );
     public static final DataComponentType<BlockItemStateProperties> BLOCK_STATE = register(
         "block_state", builder -> builder.persistent(BlockItemStateProperties.CODEC).networkSynchronized(BlockItemStateProperties.STREAM_CODEC).cacheEncoding()
diff --git a/src/main/java/net/minecraft/network/protocol/game/ClientboundSetEntityDataPacket.java b/src/main/java/net/minecraft/network/protocol/game/ClientboundSetEntityDataPacket.java
index 59c1c103545f04fd35e6932df64a9910a1d74cd7..56bde49e6b7790155b032d0be40961d566ab89e9 100644
--- a/src/main/java/net/minecraft/network/protocol/game/ClientboundSetEntityDataPacket.java
+++ b/src/main/java/net/minecraft/network/protocol/game/ClientboundSetEntityDataPacket.java
@@ -19,9 +19,11 @@ public record ClientboundSetEntityDataPacket(int id, List<SynchedEntityData.Data
     }
 
     private static void pack(List<SynchedEntityData.DataValue<?>> trackedValues, RegistryFriendlyByteBuf buf) {
+        try (var ignored = io.papermc.paper.util.DataSanitizationUtil.start(true)) { // Paper - data sanitization
         for (SynchedEntityData.DataValue<?> dataValue : trackedValues) {
             dataValue.write(buf);
         }
+        } // Paper - data sanitization
 
         buf.writeByte(255);
     }
diff --git a/src/main/java/net/minecraft/network/protocol/game/ClientboundSetEquipmentPacket.java b/src/main/java/net/minecraft/network/protocol/game/ClientboundSetEquipmentPacket.java
index e092a486c4041ab1cfe9e29c88d0d94528a6e9a6..3945ca04ede578121b370592482ac917f2d4cf96 100644
--- a/src/main/java/net/minecraft/network/protocol/game/ClientboundSetEquipmentPacket.java
+++ b/src/main/java/net/minecraft/network/protocol/game/ClientboundSetEquipmentPacket.java
@@ -19,6 +19,13 @@ public class ClientboundSetEquipmentPacket implements Packet<ClientGamePacketLis
     private final List<Pair<EquipmentSlot, ItemStack>> slots;
 
     public ClientboundSetEquipmentPacket(int id, List<Pair<EquipmentSlot, ItemStack>> equipmentList) {
+        // Paper start - data sanitization
+        this(id, equipmentList, false);
+    }
+    private boolean sanitize = false;
+    public ClientboundSetEquipmentPacket(int id, List<Pair<EquipmentSlot, ItemStack>> equipmentList, boolean sanitize) {
+        this.sanitize = sanitize;
+        // Paper end - data sanitization
         this.entity = id;
         this.slots = equipmentList;
     }
@@ -41,6 +48,7 @@ public class ClientboundSetEquipmentPacket implements Packet<ClientGamePacketLis
         buf.writeVarInt(this.entity);
         int i = this.slots.size();
 
+        try (var ignored = io.papermc.paper.util.DataSanitizationUtil.start(this.sanitize)) {  // Paper - data sanitization
         for (int j = 0; j < i; j++) {
             Pair<EquipmentSlot, ItemStack> pair = this.slots.get(j);
             EquipmentSlot equipmentSlot = pair.getFirst();
@@ -49,6 +57,7 @@ public class ClientboundSetEquipmentPacket implements Packet<ClientGamePacketLis
             buf.writeByte(bl ? k | -128 : k);
             ItemStack.OPTIONAL_STREAM_CODEC.encode(buf, pair.getSecond());
         }
+        } // Paper - data sanitization
     }
 
     @Override
diff --git a/src/main/java/net/minecraft/server/level/ServerEntity.java b/src/main/java/net/minecraft/server/level/ServerEntity.java
index 0e7ace92522fbd4cef7b2c2b8a0f8b86c2cce192..1d849ce4e2c85f149af25318b8ffb6dcef6c6788 100644
--- a/src/main/java/net/minecraft/server/level/ServerEntity.java
+++ b/src/main/java/net/minecraft/server/level/ServerEntity.java
@@ -349,7 +349,7 @@ public class ServerEntity {
             }
 
             if (!list.isEmpty()) {
-                sender.accept(new ClientboundSetEquipmentPacket(this.entity.getId(), list));
+                sender.accept(new ClientboundSetEquipmentPacket(this.entity.getId(), list, true)); // Paper - data sanitization
             }
             ((LivingEntity) this.entity).detectEquipmentUpdatesPublic(); // CraftBukkit - SPIGOT-3789: sync again immediately after sending
         }
diff --git a/src/main/java/net/minecraft/server/network/ServerGamePacketListenerImpl.java b/src/main/java/net/minecraft/server/network/ServerGamePacketListenerImpl.java
index 60c65af218d533d53b765ba2175fed163c32c126..a0f5839719ca0ce6ed048229f074041b4f64cc97 100644
--- a/src/main/java/net/minecraft/server/network/ServerGamePacketListenerImpl.java
+++ b/src/main/java/net/minecraft/server/network/ServerGamePacketListenerImpl.java
@@ -2732,7 +2732,7 @@ public class ServerGamePacketListenerImpl extends ServerCommonPacketListenerImpl
                                 entity.refreshEntityData(ServerGamePacketListenerImpl.this.player);
                                 // SPIGOT-7136 - Allays
                                 if (entity instanceof Allay) {
-                                    ServerGamePacketListenerImpl.this.send(new ClientboundSetEquipmentPacket(entity.getId(), Arrays.stream(net.minecraft.world.entity.EquipmentSlot.values()).map((slot) -> Pair.of(slot, ((LivingEntity) entity).getItemBySlot(slot).copy())).collect(Collectors.toList())));
+                                    ServerGamePacketListenerImpl.this.send(new ClientboundSetEquipmentPacket(entity.getId(), Arrays.stream(net.minecraft.world.entity.EquipmentSlot.values()).map((slot) -> Pair.of(slot, ((LivingEntity) entity).getItemBySlot(slot).copy())).collect(Collectors.toList()), true)); // Paper - sanitize
                                     ServerGamePacketListenerImpl.this.player.containerMenu.sendAllDataToRemote();
                                 }
                             }
diff --git a/src/main/java/net/minecraft/world/entity/LivingEntity.java b/src/main/java/net/minecraft/world/entity/LivingEntity.java
index 66707853328b6b23771c88abd0cf5a7ef766bb71..7a6c8a64bd119fd1f2fc245f84cbb332ecd937e3 100644
--- a/src/main/java/net/minecraft/world/entity/LivingEntity.java
+++ b/src/main/java/net/minecraft/world/entity/LivingEntity.java
@@ -3322,7 +3322,7 @@ public abstract class LivingEntity extends Entity implements Attackable {
             }
 
         });
-        ((ServerLevel) this.level()).getChunkSource().broadcast(this, new ClientboundSetEquipmentPacket(this.getId(), list));
+        ((ServerLevel) this.level()).getChunkSource().broadcast(this, new ClientboundSetEquipmentPacket(this.getId(), list, true)); // Paper - data sanitization
     }
 
     private ItemStack getLastArmorItem(EquipmentSlot slot) {
