Add option to replace ping packets by using container acks

Closes ViaVersion/ViaVersion#2624

common/src/main/java/com/viaversion/viabackwards/ViaBackwardsConfig.java

@@ -31,6 +31,7 @@ public class ViaBackwardsConfig extends Config implements com.viaversion.viaback
     private boolean addTeamColorToPrefix;
     private boolean fix1_13FacePlayer;
     private boolean alwaysShowOriginalMobName;
+    private boolean handlePingsAsInvAcknowledgements;
 
     public ViaBackwardsConfig(File configFile) {
         super(configFile);
@@ -47,6 +48,7 @@ public class ViaBackwardsConfig extends Config implements com.viaversion.viaback
         addTeamColorToPrefix = getBoolean("add-teamcolor-to-prefix", true);
         fix1_13FacePlayer = getBoolean("fix-1_13-face-player", false);
         alwaysShowOriginalMobName = getBoolean("always-show-original-mob-name", true);
+        handlePingsAsInvAcknowledgements = getBoolean("handle-pings-as-inv-acknowledgements", false);
     }
 
     @Override
@@ -69,6 +71,11 @@ public class ViaBackwardsConfig extends Config implements com.viaversion.viaback
         return alwaysShowOriginalMobName;
     }
 
+    @Override
+    public boolean handlePingsAsInvAcknowledgements() {
+        return handlePingsAsInvAcknowledgements || Boolean.getBoolean("com.viaversion.handlePingsAsInvAcknowledgements");
+    }
+
     @Override
     public URL getDefaultConfigURL() {
         return getClass().getClassLoader().getResource("assets/viabackwards/config.yml");

common/src/main/java/com/viaversion/viabackwards/api/ViaBackwardsConfig.java

@@ -46,4 +46,6 @@ public interface ViaBackwardsConfig {
      * @return true if enabled
      */
     boolean alwaysShowOriginalMobName();
+
+    boolean handlePingsAsInvAcknowledgements();
 }

common/src/main/java/com/viaversion/viabackwards/protocol/protocol1_11_1to1_12/packets/BlockItemPackets1_12.java

@@ -145,7 +145,7 @@ public class BlockItemPackets1_12 extends LegacyBlockItemRewriter<Protocol1_11_1
 
                             // Apologize (may happen in some cases, maybe if inventory is full?)
                             PacketWrapper confirm = wrapper.create(ServerboundPackets1_12.WINDOW_CONFIRMATION);
-                            confirm.write(Type.BYTE, wrapper.get(Type.UNSIGNED_BYTE, 0).byteValue());
+                            confirm.write(Type.UNSIGNED_BYTE, wrapper.get(Type.UNSIGNED_BYTE, 0));
                             confirm.write(Type.SHORT, wrapper.get(Type.SHORT, 1));
                             confirm.write(Type.BOOLEAN, false); // Success - not used
 

common/src/main/java/com/viaversion/viabackwards/protocol/protocol1_16_4to1_17/Protocol1_16_4To1_17.java

@@ -17,12 +17,14 @@
  */
 package com.viaversion.viabackwards.protocol.protocol1_16_4to1_17;
 
+import com.viaversion.viabackwards.ViaBackwards;
 import com.viaversion.viabackwards.api.BackwardsProtocol;
 import com.viaversion.viabackwards.api.data.BackwardsMappings;
 import com.viaversion.viabackwards.api.rewriters.SoundRewriter;
 import com.viaversion.viabackwards.api.rewriters.TranslatableRewriter;
 import com.viaversion.viabackwards.protocol.protocol1_16_4to1_17.packets.BlockItemPackets1_17;
 import com.viaversion.viabackwards.protocol.protocol1_16_4to1_17.packets.EntityPackets1_17;
+import com.viaversion.viabackwards.protocol.protocol1_16_4to1_17.storage.PingRequests;
 import com.viaversion.viaversion.api.connection.UserConnection;
 import com.viaversion.viaversion.api.minecraft.RegistryType;
 import com.viaversion.viaversion.api.minecraft.TagData;
@@ -186,8 +188,21 @@ public final class Protocol1_16_4To1_17 extends BackwardsProtocol<ClientboundPac
                 handler(wrapper -> {
                     wrapper.cancel();
 
-                    // Plugins expecting a real response will have to handle this accordingly themselves
                     int id = wrapper.read(Type.INT);
+                    short shortId = (short) id;
+                    if (id == shortId && ViaBackwards.getConfig().handlePingsAsInvAcknowledgements()) {
+                        wrapper.user().get(PingRequests.class).addId(shortId);
+
+                        // Send inventory acknowledgement to replace ping packet functionality in the unsigned byte range
+                        PacketWrapper acknowledgementPacket = wrapper.create(ClientboundPackets1_16_2.WINDOW_CONFIRMATION);
+                        acknowledgementPacket.write(Type.UNSIGNED_BYTE, (short) 0); // Inventory id
+                        acknowledgementPacket.write(Type.SHORT, shortId); // Confirmation id
+                        acknowledgementPacket.write(Type.BOOLEAN, false); // Accepted
+                        acknowledgementPacket.send(Protocol1_16_4To1_17.class);
+                        return;
+                    }
+
+                    // Plugins expecting a real response will have to handle this accordingly themselves
                     PacketWrapper pongPacket = wrapper.create(ServerboundPackets1_17.PONG);
                     pongPacket.write(Type.INT, id);
                     pongPacket.sendToServer(Protocol1_16_4To1_17.class);
@@ -233,6 +248,7 @@ public final class Protocol1_16_4To1_17 extends BackwardsProtocol<ClientboundPac
     @Override
     public void init(UserConnection user) {
         addEntityTracker(user, new EntityTrackerBase(user, Entity1_17Types.PLAYER));
+        user.put(new PingRequests());
     }
 
     @Override

common/src/main/java/com/viaversion/viabackwards/protocol/protocol1_16_4to1_17/packets/BlockItemPackets1_17.java

@@ -17,11 +17,13 @@
  */
 package com.viaversion.viabackwards.protocol.protocol1_16_4to1_17.packets;
 
+import com.viaversion.viabackwards.ViaBackwards;
 import com.viaversion.viabackwards.api.rewriters.ItemRewriter;
 import com.viaversion.viabackwards.api.rewriters.MapColorRewriter;
 import com.viaversion.viabackwards.api.rewriters.TranslatableRewriter;
 import com.viaversion.viabackwards.protocol.protocol1_16_4to1_17.Protocol1_16_4To1_17;
 import com.viaversion.viabackwards.protocol.protocol1_16_4to1_17.data.MapColorRewrites;
+import com.viaversion.viabackwards.protocol.protocol1_16_4to1_17.storage.PingRequests;
 import com.viaversion.viaversion.api.data.entity.EntityTracker;
 import com.viaversion.viaversion.api.minecraft.BlockChangeRecord;
 import com.viaversion.viaversion.api.minecraft.chunks.Chunk;
@@ -34,6 +36,7 @@ import com.viaversion.viaversion.protocols.protocol1_16_2to1_16_1.ServerboundPac
 import com.viaversion.viaversion.protocols.protocol1_16_2to1_16_1.types.Chunk1_16_2Type;
 import com.viaversion.viaversion.protocols.protocol1_16to1_15_2.data.RecipeRewriter1_16;
 import com.viaversion.viaversion.protocols.protocol1_17to1_16_4.ClientboundPackets1_17;
+import com.viaversion.viaversion.protocols.protocol1_17to1_16_4.ServerboundPackets1_17;
 import com.viaversion.viaversion.protocols.protocol1_17to1_16_4.types.Chunk1_17Type;
 import com.viaversion.viaversion.rewriter.BlockRewriter;
 
@@ -92,7 +95,27 @@ public final class BlockItemPackets1_17 extends ItemRewriter<Protocol1_16_4To1_1
                 });
             }
         });
-        protocol.cancelServerbound(ServerboundPackets1_16_2.WINDOW_CONFIRMATION);
+        protocol.registerServerbound(ServerboundPackets1_16_2.WINDOW_CONFIRMATION, null, new PacketRemapper() {
+            @Override
+            public void registerMap() {
+                handler(wrapper -> {
+                    wrapper.cancel();
+                    if (!ViaBackwards.getConfig().handlePingsAsInvAcknowledgements()) {
+                        return;
+                    }
+
+                    // Handle ping packet replacement
+                    short inventoryId = wrapper.read(Type.UNSIGNED_BYTE);
+                    short confirmationId = wrapper.read(Type.SHORT);
+                    boolean accepted = wrapper.read(Type.BOOLEAN);
+                    if (inventoryId == 0 && accepted && wrapper.user().get(PingRequests.class).removeId(confirmationId)) {
+                        PacketWrapper pongPacket = wrapper.create(ServerboundPackets1_17.PONG);
+                        pongPacket.write(Type.INT, (int) confirmationId);
+                        pongPacket.sendToServer(Protocol1_16_4To1_17.class);
+                    }
+                });
+            }
+        });
 
         protocol.registerClientbound(ClientboundPackets1_17.SPAWN_PARTICLE, new PacketRemapper() {
             @Override

common/src/main/java/com/viaversion/viabackwards/protocol/protocol1_16_4to1_17/storage/PingRequests.java

@@ -0,0 +1,34 @@
+/*
+ * This file is part of ViaVersion - https://github.com/ViaVersion/ViaVersion
+ * Copyright (C) 2016-2021 ViaVersion and contributors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+package com.viaversion.viabackwards.protocol.protocol1_16_4to1_17.storage;
+
+import com.viaversion.viaversion.api.connection.StorableObject;
+import com.viaversion.viaversion.libs.fastutil.ints.IntOpenHashSet;
+import com.viaversion.viaversion.libs.fastutil.ints.IntSet;
+
+public final class PingRequests implements StorableObject {
+    private final IntSet ids = new IntOpenHashSet();
+
+    public void addId(short id) {
+        ids.add(id);
+    }
+
+    public boolean removeId(short id) {
+        return ids.remove(id);
+    }
+}

common/src/main/resources/assets/viabackwards/config.yml

@@ -11,4 +11,8 @@ add-custom-enchants-into-lore: true
 add-teamcolor-to-prefix: true
 #
 # Converts the 1.13 face look-at packet for 1.12- players. Requires a bit of extra caching.
-fix-1_13-face-player: false
+fix-1_13-face-player: false
+#
+# Sends inventory acknowledgement packets to act as a replacement for ping packets for sub 1.17 clients.
+# This only takes effect for ids in the short range. Useful for anticheat compatibility.
+handle-pings-as-inv-acknowledgements: false