#3808: Do not decode packets that we don't handle

protocol/src/main/java/net/md_5/bungee/protocol/AbstractPacketHandler.java

@@ -8,7 +8,6 @@ import net.md_5.bungee.protocol.packet.ClearTitles;
 import net.md_5.bungee.protocol.packet.ClientChat;
 import net.md_5.bungee.protocol.packet.ClientCommand;
 import net.md_5.bungee.protocol.packet.ClientSettings;
-import net.md_5.bungee.protocol.packet.ClientStatus;
 import net.md_5.bungee.protocol.packet.Commands;
 import net.md_5.bungee.protocol.packet.CookieRequest;
 import net.md_5.bungee.protocol.packet.CookieResponse;
@@ -128,10 +127,6 @@ public abstract class AbstractPacketHandler
     {
     }
 
-    public void handle(ClientStatus clientStatus) throws Exception
-    {
-    }
-
     public void handle(PlayerListItem playerListItem) throws Exception
     {
     }

protocol/src/main/java/net/md_5/bungee/protocol/Protocol.java

@@ -131,7 +131,8 @@ public enum Protocol
                     map( ProtocolConstants.MINECRAFT_1_21_2, 0x2C ),
                     map( ProtocolConstants.MINECRAFT_1_21_5, 0x2B )
             );
-            TO_CLIENT.registerPacket( Chat.class,
+            TO_CLIENT.registerPacket(
+                    Chat.class,
                     Chat::new,
                     map( ProtocolConstants.MINECRAFT_1_8, 0x02 ),
                     map( ProtocolConstants.MINECRAFT_1_9, 0x0F ),
@@ -337,6 +338,7 @@ public enum Protocol
             TO_CLIENT.registerPacket(
                     Title.class,
                     Title::new,
+                    RegisterType.ENCODE,
                     map( ProtocolConstants.MINECRAFT_1_8, 0x45 ),
                     map( ProtocolConstants.MINECRAFT_1_12, 0x47 ),
                     map( ProtocolConstants.MINECRAFT_1_12_1, 0x48 ),
@@ -358,6 +360,7 @@ public enum Protocol
             TO_CLIENT.registerPacket(
                     ClearTitles.class,
                     ClearTitles::new,
+                    RegisterType.ENCODE,
                     map( ProtocolConstants.MINECRAFT_1_17, 0x10 ),
                     map( ProtocolConstants.MINECRAFT_1_19, 0x0D ),
                     map( ProtocolConstants.MINECRAFT_1_19_3, 0x0C ),
@@ -368,6 +371,7 @@ public enum Protocol
             TO_CLIENT.registerPacket(
                     Subtitle.class,
                     Subtitle::new,
+                    RegisterType.ENCODE,
                     map( ProtocolConstants.MINECRAFT_1_17, 0x57 ),
                     map( ProtocolConstants.MINECRAFT_1_18, 0x58 ),
                     map( ProtocolConstants.MINECRAFT_1_19_1, 0x5B ),
@@ -382,6 +386,7 @@ public enum Protocol
             TO_CLIENT.registerPacket(
                     TitleTimes.class,
                     TitleTimes::new,
+                    RegisterType.ENCODE,
                     map( ProtocolConstants.MINECRAFT_1_17, 0x5A ),
                     map( ProtocolConstants.MINECRAFT_1_18, 0x5B ),
                     map( ProtocolConstants.MINECRAFT_1_19_1, 0x5E ),
@@ -396,6 +401,7 @@ public enum Protocol
             TO_CLIENT.registerPacket(
                     SystemChat.class,
                     SystemChat::new,
+                    RegisterType.ENCODE,
                     map( ProtocolConstants.MINECRAFT_1_19, 0x5F ),
                     map( ProtocolConstants.MINECRAFT_1_19_1, 0x62 ),
                     map( ProtocolConstants.MINECRAFT_1_19_3, 0x60 ),
@@ -409,6 +415,7 @@ public enum Protocol
             TO_CLIENT.registerPacket(
                     PlayerListHeaderFooter.class,
                     PlayerListHeaderFooter::new,
+                    RegisterType.ENCODE,
                     map( ProtocolConstants.MINECRAFT_1_8, 0x47 ),
                     map( ProtocolConstants.MINECRAFT_1_9, 0x48 ),
                     map( ProtocolConstants.MINECRAFT_1_9_4, 0x47 ),
@@ -433,6 +440,7 @@ public enum Protocol
             TO_CLIENT.registerPacket(
                     EntityStatus.class,
                     EntityStatus::new,
+                    RegisterType.ENCODE,
                     map( ProtocolConstants.MINECRAFT_1_8, 0x1A ),
                     map( ProtocolConstants.MINECRAFT_1_9, 0x1B ),
                     map( ProtocolConstants.MINECRAFT_1_13, 0x1C ),
@@ -466,6 +474,7 @@ public enum Protocol
             TO_CLIENT.registerPacket(
                     GameState.class,
                     GameState::new,
+                    RegisterType.ENCODE,
                     map( ProtocolConstants.MINECRAFT_1_15, 0x1F ),
                     map( ProtocolConstants.MINECRAFT_1_16, 0x1E ),
                     map( ProtocolConstants.MINECRAFT_1_16_2, 0x1D ),
@@ -482,6 +491,7 @@ public enum Protocol
             TO_CLIENT.registerPacket(
                     ViewDistance.class,
                     ViewDistance::new,
+                    RegisterType.ENCODE,
                     map( ProtocolConstants.MINECRAFT_1_14, 0x41 ),
                     map( ProtocolConstants.MINECRAFT_1_15, 0x42 ),
                     map( ProtocolConstants.MINECRAFT_1_16, 0x41 ),
@@ -547,6 +557,7 @@ public enum Protocol
             TO_CLIENT.registerPacket(
                     StoreCookie.class,
                     StoreCookie::new,
+                    RegisterType.ENCODE,
                     map( ProtocolConstants.MINECRAFT_1_20_5, 0x6B ),
                     map( ProtocolConstants.MINECRAFT_1_21_2, 0x72 ),
                     map( ProtocolConstants.MINECRAFT_1_21_5, 0x71 )
@@ -554,29 +565,34 @@ public enum Protocol
             TO_CLIENT.registerPacket(
                     Transfer.class,
                     Transfer::new,
+                    RegisterType.ENCODE,
                     map( ProtocolConstants.MINECRAFT_1_20_5, 0x73 ),
                     map( ProtocolConstants.MINECRAFT_1_21_2, 0x7A )
             );
             TO_CLIENT.registerPacket(
                     DisconnectReportDetails.class,
                     DisconnectReportDetails::new,
+                    RegisterType.ENCODE,
                     map( ProtocolConstants.MINECRAFT_1_21, 0x7A ),
                     map( ProtocolConstants.MINECRAFT_1_21_2, 0x81 )
             );
             TO_CLIENT.registerPacket(
                     ServerLinks.class,
                     ServerLinks::new,
+                    RegisterType.ENCODE,
                     map( ProtocolConstants.MINECRAFT_1_21, 0x7B ),
                     map( ProtocolConstants.MINECRAFT_1_21_2, 0x82 )
             );
             TO_CLIENT.registerPacket(
                     ClearDialog.class,
                     ClearDialog::new,
+                    RegisterType.ENCODE,
                     map( ProtocolConstants.MINECRAFT_1_21_6, 0x84 )
             );
             TO_CLIENT.registerPacket(
                     ShowDialog.class,
                     ShowDialog::new,
+                    RegisterType.ENCODE,
                     map( ProtocolConstants.MINECRAFT_1_21_6, 0x85 )
             );
 
@@ -841,31 +857,37 @@ public enum Protocol
             TO_CLIENT.registerPacket(
                     StoreCookie.class,
                     StoreCookie::new,
+                    RegisterType.ENCODE,
                     map( ProtocolConstants.MINECRAFT_1_20_5, 0x0A )
             );
             TO_CLIENT.registerPacket(
                     Transfer.class,
                     Transfer::new,
+                    RegisterType.ENCODE,
                     map( ProtocolConstants.MINECRAFT_1_20_5, 0x0B )
             );
             TO_CLIENT.registerPacket(
                     DisconnectReportDetails.class,
                     DisconnectReportDetails::new,
+                    RegisterType.ENCODE,
                     map( ProtocolConstants.MINECRAFT_1_21, 0x0F )
             );
             TO_CLIENT.registerPacket(
                     ServerLinks.class,
                     ServerLinks::new,
+                    RegisterType.ENCODE,
                     map( ProtocolConstants.MINECRAFT_1_21, 0x10 )
             );
             TO_CLIENT.registerPacket(
                     ClearDialog.class,
                     ClearDialog::new,
+                    RegisterType.ENCODE,
                     map( ProtocolConstants.MINECRAFT_1_21_6, 0x11 )
             );
             TO_CLIENT.registerPacket(
                     ShowDialogDirect.class,
                     ShowDialogDirect::new,
+                    RegisterType.ENCODE,
                     map( ProtocolConstants.MINECRAFT_1_21_6, 0x12 )
             );
 
@@ -957,6 +979,26 @@ public enum Protocol
         private final int packetID;
     }
 
+    private enum RegisterType
+    {
+        // packet is registered to be encoded (only sent, never handled)
+        ENCODE,
+        // packet is registered to be decoded (only handled never modified)
+        DECODE,
+        // packet is registered to be both, encoded and decoded
+        BOTH;
+
+        public boolean encode()
+        {
+            return this == BOTH || this == ENCODE;
+        }
+
+        public boolean decode()
+        {
+            return this == BOTH || this == DECODE;
+        }
+    }
+
     // Helper method
     private static ProtocolMapping map(int protocol, int id)
     {
@@ -1010,6 +1052,11 @@ public enum Protocol
         }
 
         private void registerPacket(Class<? extends DefinedPacket> packetClass, Supplier<? extends DefinedPacket> constructor, ProtocolMapping... mappings)
+        {
+            registerPacket( packetClass, constructor, RegisterType.BOTH, mappings );
+        }
+
+        private void registerPacket(Class<? extends DefinedPacket> packetClass, Supplier<? extends DefinedPacket> constructor, RegisterType registerType, ProtocolMapping... mappings)
         {
             int mappingIndex = 0;
             ProtocolMapping mapping = mappings[mappingIndex];
@@ -1042,11 +1089,18 @@ public enum Protocol
 
                 ProtocolData data = protocols.get( protocol );
                 Preconditions.checkState( data.packetConstructors[mapping.packetID] == null, "Duplicate packet mapping (%s)", mapping.packetID );
+                Preconditions.checkState( !data.packetMap.containsKey( packetClass ), "Duplicate packet mapping (%s)", mapping.packetID );
 
+                if ( registerType.encode() )
+                {
                     data.packetMap.put( packetClass, mapping.packetID );
+                }
+                if ( registerType.decode() )
+                {
                     data.packetConstructors[mapping.packetID] = constructor;
                 }
             }
+        }
 
         public boolean hasPacket(Class<? extends DefinedPacket> packet, int version)
         {

protocol/src/main/java/net/md_5/bungee/protocol/packet/ClientStatus.java

@@ -1,37 +0,0 @@
-package net.md_5.bungee.protocol.packet;
-
-import io.netty.buffer.ByteBuf;
-import lombok.AllArgsConstructor;
-import lombok.Data;
-import lombok.EqualsAndHashCode;
-import lombok.NoArgsConstructor;
-import net.md_5.bungee.protocol.AbstractPacketHandler;
-import net.md_5.bungee.protocol.DefinedPacket;
-
-@Data
-@NoArgsConstructor
-@AllArgsConstructor
-@EqualsAndHashCode(callSuper = false)
-public class ClientStatus extends DefinedPacket
-{
-
-    private byte payload;
-
-    @Override
-    public void read(ByteBuf buf)
-    {
-        payload = buf.readByte();
-    }
-
-    @Override
-    public void write(ByteBuf buf)
-    {
-        buf.writeByte( payload );
-    }
-
-    @Override
-    public void handle(AbstractPacketHandler handler) throws Exception
-    {
-        handler.handle( this );
-    }
-}