Fix: UpstreamPacketHandlers' own packet handlers' exceptions not getting caught and logged (#6575)

Author: onebeastchris

core/src/main/java/org/geysermc/geyser/network/CodecProcessor.java

@@ -89,6 +89,7 @@
 import org.cloudburstmc.protocol.bedrock.packet.SubChunkRequestPacket;
 import org.cloudburstmc.protocol.bedrock.packet.SubClientLoginPacket;
 import org.cloudburstmc.protocol.common.util.VarInts;
+import org.geysermc.geyser.network.netty.IllegalPacketException;
 
 /**
  * Processes the Bedrock codec to remove or modify unused or unsafe packets and fields.
@@ -103,12 +104,12 @@ class CodecProcessor {
     static final BedrockPacketSerializer ILLEGAL_SERIALIZER = new BedrockPacketSerializer<>() {
         @Override
         public void serialize(ByteBuf buffer, BedrockCodecHelper helper, BedrockPacket packet) {
-            throw new IllegalArgumentException("Server tried to send unused packet " + packet.getClass().getSimpleName() + "!");
+            throw new IllegalPacketException("Server tried to send unused packet " + packet.getClass().getSimpleName() + "!");
         }
 
         @Override
         public void deserialize(ByteBuf buffer, BedrockCodecHelper helper, BedrockPacket packet) {
-            throw new IllegalArgumentException("Client tried to send unused packet " + packet.getClass().getSimpleName() + "!");
+            throw new IllegalPacketException("Client tried to send unused packet " + packet.getClass().getSimpleName() + "!");
         }
     };
 
@@ -131,14 +132,14 @@ public void deserialize(ByteBuf buffer, BedrockCodecHelper helper, BedrockPacket
     private static final BedrockPacketSerializer<InventoryContentPacket> INVENTORY_CONTENT_SERIALIZER_V748 = new InventoryContentSerializer_v748() {
         @Override
         public void deserialize(ByteBuf buffer, BedrockCodecHelper helper, InventoryContentPacket packet) {
-            throw new IllegalArgumentException("Client cannot send InventoryContentPacket in server-auth inventory environment!");
+            throw new IllegalPacketException("Client cannot send InventoryContentPacket in server-auth inventory environment!");
         }
     };
 
     private static final BedrockPacketSerializer<InventoryContentPacket> INVENTORY_CONTENT_SERIALIZER_V1001 = new InventoryContentSerializer_v1001() {
         @Override
         public void deserialize(ByteBuf buffer, BedrockCodecHelper helper, InventoryContentPacket packet) {
-            throw new IllegalArgumentException("Client cannot send InventoryContentPacket in server-auth inventory environment!");
+            throw new IllegalPacketException("Client cannot send InventoryContentPacket in server-auth inventory environment!");
         }
     };
 
@@ -148,35 +149,35 @@ public void deserialize(ByteBuf buffer, BedrockCodecHelper helper, InventoryCont
     private static final BedrockPacketSerializer<InventorySlotPacket> INVENTORY_SLOT_SERIALIZER_V748 = new InventorySlotSerializer_v748() {
         @Override
         public void deserialize(ByteBuf buffer, BedrockCodecHelper helper, InventorySlotPacket packet) {
-            throw new IllegalArgumentException("Client cannot send InventorySlotPacket in server-auth inventory environment!");
+            throw new IllegalPacketException("Client cannot send InventorySlotPacket in server-auth inventory environment!");
         }
     };
 
     private static final BedrockPacketSerializer<InventorySlotPacket> INVENTORY_SLOT_SERIALIZER_V975 = new InventorySlotSerializer_v975() {
         @Override
         public void deserialize(ByteBuf buffer, BedrockCodecHelper helper, InventorySlotPacket packet) {
-            throw new IllegalArgumentException("Client cannot send InventorySlotPacket in server-auth inventory environment!");
+            throw new IllegalPacketException("Client cannot send InventorySlotPacket in server-auth inventory environment!");
         }
     };
 
     private static final BedrockPacketSerializer<MovePlayerPacket> MOVE_PLAYER_SERIALIZER = new MovePlayerSerializer_v419() {
         @Override
         public void deserialize(ByteBuf buffer, BedrockCodecHelper helper, MovePlayerPacket packet) {
-            throw new IllegalArgumentException("Client cannot send MovePlayerPacket in server-auth movement environment!");
+            throw new IllegalPacketException("Client cannot send MovePlayerPacket in server-auth movement environment!");
         }
     };
 
     private static final BedrockPacketSerializer<MoveEntityAbsolutePacket> MOVE_ENTITY_SERIALIZER_V291 = new MoveEntityAbsoluteSerializer_v291() {
         @Override
         public void deserialize(ByteBuf buffer, BedrockCodecHelper helper, MoveEntityAbsolutePacket packet) {
-            throw new IllegalArgumentException("Client cannot send MoveEntityAbsolutePacket in server-auth movement environment!");
+            throw new IllegalPacketException("Client cannot send MoveEntityAbsolutePacket in server-auth movement environment!");
         }
     };
 
     private static final BedrockPacketSerializer<MoveEntityAbsolutePacket> MOVE_ENTITY_SERIALIZER_V975 = new MoveEntityAbsoluteSerializer_v975() {
         @Override
         public void deserialize(ByteBuf buffer, BedrockCodecHelper helper, MoveEntityAbsolutePacket packet) {
-            throw new IllegalArgumentException("Client cannot send MoveEntityAbsolutePacket in server-auth movement environment!");
+            throw new IllegalPacketException("Client cannot send MoveEntityAbsolutePacket in server-auth movement environment!");
         }
     };
 
@@ -396,7 +397,7 @@ private static void fakeItemDescriptorRead(ByteBuf buffer) {
                     VarInts.readInt(buffer); // netId
                     break;
                 default:
-                    throw new IllegalArgumentException("Not oneOf<ItemStackNetId, ItemStackRequestId, ItemStackLegacyRequestId>");
+                    throw new IllegalPacketException("Not oneOf<ItemStackNetId, ItemStackRequestId, ItemStackLegacyRequestId>");
             }
         }
         VarInts.readUnsignedInt(buffer); // block runtime id

core/src/main/java/org/geysermc/geyser/network/GeyserServerInitializer.java

@@ -33,7 +33,6 @@
 import org.cloudburstmc.netty.channel.raknet.config.RakChannelOption;
 import org.cloudburstmc.protocol.bedrock.BedrockPeer;
 import org.cloudburstmc.protocol.bedrock.BedrockServerSession;
-import org.cloudburstmc.protocol.bedrock.netty.codec.packet.BedrockPacketCodec;
 import org.cloudburstmc.protocol.bedrock.netty.initializer.BedrockServerInitializer;
 import org.geysermc.geyser.GeyserImpl;
 import org.geysermc.geyser.session.GeyserSession;
@@ -66,7 +65,10 @@ public void initSession(@NonNull BedrockServerSession bedrockServerSession) {
 
             if (!bedrockServerSession.isSubClient()) {
                 Channel channel = bedrockServerSession.getPeer().getChannel();
-                channel.pipeline().addAfter(BedrockPacketCodec.NAME, InvalidPacketHandler.NAME, new InvalidPacketHandler(session));
+                // Added after BedrockPeer, not BedrockPacketCodec to ensure exceptions thrown while dispatching
+                // to the packet handler also get here if no other handler exists
+                // FIXME not ideal for e.g. UpstreamPacketHandler having a couple of its own packet handlers
+                channel.pipeline().addAfter(BedrockPeer.NAME, InvalidPacketHandler.NAME, new InvalidPacketHandler(session));
             }
 
             bedrockServerSession.setPacketHandler(new UpstreamPacketHandler(this.geyser, session));

core/src/main/java/org/geysermc/geyser/network/InvalidPacketHandler.java

@@ -30,6 +30,7 @@
 import lombok.RequiredArgsConstructor;
 import org.geysermc.geyser.GeyserImpl;
 import org.geysermc.geyser.GeyserLogger;
+import org.geysermc.geyser.network.netty.IllegalPacketException;
 import org.geysermc.geyser.session.GeyserSession;
 
 import java.util.stream.Stream;
@@ -49,7 +50,7 @@ public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws E
 
         GeyserLogger logger = GeyserImpl.getInstance().getLogger();
 
-        if (!(rootCause instanceof IllegalArgumentException)) {
+        if (!(rootCause instanceof IllegalPacketException)) {
             // Kick users that cause exceptions
             logger.error("Exception caught in session of " + session.bedrockUsername(), cause);
             session.disconnect("An internal error occurred!");

core/src/main/java/org/geysermc/geyser/network/UpstreamPacketHandler.java

@@ -51,7 +51,6 @@
 import org.cloudburstmc.protocol.bedrock.packet.SetTitlePacket;
 import org.cloudburstmc.protocol.common.PacketSignal;
 import org.cloudburstmc.protocol.common.util.Zlib;
-import org.geysermc.api.util.BedrockPlatform;
 import org.geysermc.geyser.Constants;
 import org.geysermc.geyser.GeyserImpl;
 import org.geysermc.geyser.api.event.bedrock.SessionInitializeEvent;
@@ -168,10 +167,8 @@ public PacketSignal handle(RequestNetworkSettingsPacket packet) {
         }
 
         // New since 1.19.30 - sent before login packet
-        PacketCompressionAlgorithm algorithm = PacketCompressionAlgorithm.ZLIB;
-
         NetworkSettingsPacket responsePacket = new NetworkSettingsPacket();
-        responsePacket.setCompressionAlgorithm(algorithm);
+        responsePacket.setCompressionAlgorithm(PacketCompressionAlgorithm.ZLIB);
         responsePacket.setCompressionThreshold(512);
         session.sendUpstreamPacketImmediately(responsePacket);
         session.getUpstream().getSession().getPeer().setCompression(compressionStrategy);

core/src/main/java/org/geysermc/geyser/network/netty/IllegalPacketException.java

@@ -0,0 +1,38 @@
+/*
+ * Copyright (c) 2026 GeyserMC. http://geysermc.org
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ *
+ * @author GeyserMC
+ * @link https://github.com/GeyserMC/Geyser
+ */
+
+package org.geysermc.geyser.network.netty;
+
+import org.geysermc.geyser.network.InvalidPacketHandler;
+
+/**
+ * A wrapper for an {@link IllegalArgumentException} thrown for invalid packets only
+ * Used in {@link InvalidPacketHandler} to identify the exception cause
+ */
+public class IllegalPacketException extends IllegalArgumentException {
+    public IllegalPacketException(String message) {
+        super(message);
+    }
+}