Introduce support for Minecraft 1.21: Add ReflectionWrapper21, ChunkHider21, and enhance version compatibility across systems.

SpigotCore/SpigotCore_21/build.gradle.kts

@@ -37,4 +37,7 @@ dependencies {
 
     compileOnly(libs.paperapi21)
     compileOnly(libs.nms21)
+    compileOnly(libs.datafixer)
+    compileOnly(libs.netty)
+    compileOnly(libs.authlib)
 }

SpigotCore/SpigotCore_21/src/de/steamwar/techhider/ChunkHider21.java

@@ -0,0 +1,155 @@
+/*
+ *   This file is a part of the SteamWar software.
+ *
+ *   Copyright (C) 2025 SteamWar.de-Serverteam
+ *
+ *   This program is free software: you can redistribute it and/or modify
+ *   it under the terms of the GNU Affero General Public License as published by
+ *   the Free Software Foundation, either version 3 of the License, or
+ *   (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ *   GNU Affero General Public License for more details.
+ *
+ *   You should have received a copy of the GNU Affero General Public License
+ *   along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package de.steamwar.techhider;
+
+import de.steamwar.Reflection;
+import io.netty.buffer.ByteBuf;
+import io.netty.buffer.Unpooled;
+import net.minecraft.network.protocol.game.ClientboundLevelChunkPacketData;
+import net.minecraft.network.protocol.game.ClientboundLevelChunkWithLightPacket;
+import net.minecraft.util.SimpleBitStorage;
+import net.minecraft.world.level.block.entity.BlockEntityType;
+import org.bukkit.entity.Player;
+
+import java.util.List;
+import java.util.Set;
+import java.util.function.BiFunction;
+import java.util.function.UnaryOperator;
+import java.util.stream.Collectors;
+
+public class ChunkHider21 implements ChunkHider {
+    @Override
+    public Class<?> mapChunkPacket() {
+        return ClientboundLevelChunkWithLightPacket.class;
+    }
+
+    private static final UnaryOperator<Object> chunkPacketCloner = ProtocolUtils.shallowCloneGenerator(ClientboundLevelChunkWithLightPacket.class);
+    private static final UnaryOperator<Object> chunkDataCloner = ProtocolUtils.shallowCloneGenerator(ClientboundLevelChunkPacketData.class);
+
+    private static final Reflection.Field<Integer> chunkXField = Reflection.getField(ClientboundLevelChunkWithLightPacket.class, int.class, 0);
+    private static final Reflection.Field<Integer> chunkZField = Reflection.getField(ClientboundLevelChunkWithLightPacket.class, int.class, 1);
+    private static final Reflection.Field<ClientboundLevelChunkPacketData> chunkData = Reflection.getField(ClientboundLevelChunkWithLightPacket.class, ClientboundLevelChunkPacketData.class, 0);
+
+    private static final Reflection.Field<byte[]> dataField = Reflection.getField(ClientboundLevelChunkPacketData.class, byte[].class, 0);
+    private static final Reflection.Field<List> tileEntities = Reflection.getField(ClientboundLevelChunkPacketData.class, List.class, 0);
+
+    @Override
+    public BiFunction<Player, Object, Object> chunkHiderGenerator(TechHider techHider) {
+        return (p, packet) -> {
+            int chunkX = chunkXField.get(packet);
+            int chunkZ = chunkZField.get(packet);
+            if (techHider.getLocationEvaluator().skipChunk(p, chunkX, chunkZ))
+                return packet;
+
+            packet = chunkPacketCloner.apply(packet);
+            Object dataWrapper = chunkDataCloner.apply(chunkData.get(packet));
+
+            Set<String> hiddenBlockEntities = techHider.getHiddenBlockEntities();
+            tileEntities.set(dataWrapper, ((List<?>)tileEntities.get(dataWrapper)).stream().filter(te -> tileEntityVisible(hiddenBlockEntities, te)).collect(Collectors.toList()));
+
+            ByteBuf in = Unpooled.wrappedBuffer(dataField.get(dataWrapper));
+            ByteBuf out = Unpooled.buffer(in.readableBytes() + 64);
+            for(int yOffset = p.getWorld().getMinHeight(); yOffset < p.getWorld().getMaxHeight(); yOffset += 16) {
+                SectionHider section = new SectionHider(p, techHider, in, out, chunkX, yOffset/16, chunkZ);
+                section.copyBlockCount();
+
+                blocks(section);
+                biomes(section);
+            }
+
+            if (in.readableBytes() != 0) {
+                throw new IllegalStateException("ChunkHider21: Incomplete chunk data, " + in.readableBytes() + " bytes left");
+            }
+
+            byte[] data = new byte[out.readableBytes()];
+            out.readBytes(data);
+            dataField.set(dataWrapper, data);
+
+            chunkData.set(packet, dataWrapper);
+            return packet;
+        };
+    }
+
+    public static final Class<?> tileEntity = Reflection.getClass("net.minecraft.network.protocol.game.ClientboundLevelChunkPacketData$BlockEntityInfo");
+    protected static final Reflection.Field<BlockEntityType> entityType = Reflection.getField(tileEntity, BlockEntityType.class, 0);
+    private static final Class<?> builtInRegestries = Reflection.getClass("net.minecraft.core.registries.BuiltInRegistries");
+    private static final Class<?> registry = Reflection.getClass("net.minecraft.core.Registry");
+    private static final Reflection.Field<?> nameField = Reflection.getField(builtInRegestries, "BLOCK_ENTITY_TYPE", registry);
+    private static final Class<?> resourceLocation = Reflection.getClass("net.minecraft.resources.ResourceLocation");
+    private static final Reflection.Method getKey = Reflection.getTypedMethod(registry, "getKey", resourceLocation, Object.class);
+    private static final Reflection.Method getName = Reflection.getTypedMethod(resourceLocation, "getPath", String.class);
+    protected boolean tileEntityVisible(Set<String> hiddenBlockEntities, Object tile) {
+        return !hiddenBlockEntities.contains(getName.invoke(getKey.invoke(nameField.get(null), entityType.get(tile))));
+    }
+
+    private void blocks(SectionHider section) {
+        section.copyBitsPerBlock();
+
+        boolean singleValued = section.getBitsPerBlock() == 0;
+        if (singleValued) {
+            int value = ProtocolUtils.readVarInt(section.getIn());
+            ProtocolUtils.writeVarInt(section.getOut(), !section.isSkipSection() && section.getObfuscate().contains(value) ? section.getTarget() : value);
+            return;
+        } else {
+            section.processPalette();
+        }
+
+        if (section.isSkipSection() || (!section.blockPrecise() && section.isPaletted())) {
+            section.skipNewDataArray(4096);
+            return;
+        }
+
+        SimpleBitStorage values = new SimpleBitStorage(section.getBitsPerBlock(), 4096, section.readNewDataArray(4096));
+
+        for (int y = 0; y < 16; y++) {
+            for (int z = 0; z < 16; z++) {
+                for (int x = 0; x < 16; x++) {
+                    int pos = (((y * 16) + z) * 16) + x;
+
+                    switch (section.test(x, y, z)) {
+                        case SKIP:
+                            break;
+                        case CHECK:
+                            if (!section.getObfuscate().contains(values.get(pos)))
+                                break;
+                        case HIDE:
+                            values.set(pos, section.getTarget());
+                            break;
+                        case HIDE_AIR:
+                        default:
+                            values.set(pos, section.getAir());
+                    }
+                }
+            }
+        }
+
+        section.writeDataArray(values.getRaw());
+    }
+
+    private void biomes(SectionHider section) {
+        section.copyBitsPerBlock();
+        if(section.getBitsPerBlock() == 0) {
+            section.copyVarInt();
+        } else if(section.getBitsPerBlock() < 6) {
+            section.skipPalette();
+            section.skipNewDataArray(64);
+        }
+    }
+}