PaperMC/patches/server/0273-Handle-Large-Packets-disconnecting-client.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Aikar <aikar@aikar.co>
Date: Tue, 27 Nov 2018 21:18:06 -0500
Subject: [PATCH] Handle Large Packets disconnecting client

If a players inventory is too big to send in a single packet,
split the inventory set into multiple packets instead.

diff --git a/src/main/java/net/minecraft/network/Connection.java b/src/main/java/net/minecraft/network/Connection.java
index 02b3f5c67b47a098f7fe15ddba0df6cb586a9ae5..157f055df00faf3a7870df8109e84fdb12f55964 100644
--- a/src/main/java/net/minecraft/network/Connection.java
+++ b/src/main/java/net/minecraft/network/Connection.java
@@ -156,6 +156,22 @@ public class Connection extends SimpleChannelInboundHandler<Packet<?>> {
     }
 
     public void exceptionCaught(ChannelHandlerContext channelhandlercontext, Throwable throwable) {
+        // Paper start - Handle large packets disconnecting client
+        if (throwable instanceof io.netty.handler.codec.EncoderException && throwable.getCause() instanceof PacketEncoder.PacketTooLargeException packetTooLargeException) {
+            final Packet<?> packet = packetTooLargeException.getPacket();
+            final io.netty.util.Attribute<ConnectionProtocol.CodecData<?>> codecDataAttribute = channelhandlercontext.channel().attr(packetTooLargeException.codecKey);
+            if (packet.packetTooLarge(this)) {
+                ProtocolSwapHandler.swapProtocolIfNeeded(codecDataAttribute, packet);
+                return;
+            } else if (packet.isSkippable()) {
+                Connection.LOGGER.debug("Skipping packet due to errors", throwable.getCause());
+                ProtocolSwapHandler.swapProtocolIfNeeded(codecDataAttribute, packet);
+                return;
+            } else {
+                throwable = throwable.getCause();
+            }
+        }
+        // Paper end - Handle large packets disconnecting client
         if (throwable instanceof SkipPacketException) {
             Connection.LOGGER.debug("Skipping packet due to errors", throwable.getCause());
         } else {
diff --git a/src/main/java/net/minecraft/network/PacketEncoder.java b/src/main/java/net/minecraft/network/PacketEncoder.java
index 7070d093c80033b61a9c8495bc56153d986b6b03..61f05f34ca33837c643f2915e753ec3935a38314 100644
--- a/src/main/java/net/minecraft/network/PacketEncoder.java
+++ b/src/main/java/net/minecraft/network/PacketEncoder.java
@@ -41,7 +41,7 @@ public class PacketEncoder extends MessageToByteEncoder<Packet<?>> {
                     int j = friendlyByteBuf.writerIndex();
                     packet.write(friendlyByteBuf);
                     int k = friendlyByteBuf.writerIndex() - j;
-                    if (k > 8388608) {
+                    if (false && k > 8388608) { // Paper - Handle large packets disconnecting client; disable
                         throw new IllegalArgumentException("Packet too big (is " + k + ", should be less than 8388608): " + packet);
                     }
 
@@ -54,10 +54,35 @@ public class PacketEncoder extends MessageToByteEncoder<Packet<?>> {
 
                     throw var13;
                 } finally {
+                    // Paper start - Handle large packets disconnecting client
+                    int packetLength = friendlyByteBuf.readableBytes();
+                    if (packetLength > MAX_PACKET_SIZE) {
+                        throw new PacketTooLargeException(packet, this.codecKey, packetLength);
+                    }
+                    // Paper end - Handle large packets disconnecting client
                     ProtocolSwapHandler.swapProtocolIfNeeded(attribute, packet);
                 }
 
             }
         }
     }
+
+    // Paper start
+    private static int MAX_PACKET_SIZE = 8388608;
+
+    public static class PacketTooLargeException extends RuntimeException {
+        private final Packet<?> packet;
+        public final AttributeKey<ConnectionProtocol.CodecData<?>> codecKey;
+
+        PacketTooLargeException(Packet<?> packet, AttributeKey<ConnectionProtocol.CodecData<?>> codecKey, int packetLength) {
+            super("PacketTooLarge - " + packet.getClass().getSimpleName() + " is " + packetLength + ". Max is " + MAX_PACKET_SIZE);
+            this.packet = packet;
+            this.codecKey = codecKey;
+        }
+
+        public Packet<?> getPacket() {
+            return this.packet;
+        }
+    }
+    // Paper end
 }
diff --git a/src/main/java/net/minecraft/network/protocol/Packet.java b/src/main/java/net/minecraft/network/protocol/Packet.java
index 700418bb0c9fbed3f161611881b1e222248ca4eb..cc658a61065d5c0021a4b88fa58b40211b94f8ec 100644
--- a/src/main/java/net/minecraft/network/protocol/Packet.java
+++ b/src/main/java/net/minecraft/network/protocol/Packet.java
@@ -10,6 +10,12 @@ public interface Packet<T extends PacketListener> {
 
     void handle(T listener);
 
+    // Paper start
+    default boolean packetTooLarge(net.minecraft.network.Connection manager) {
+        return false;
+    }
+    // Paper end
+
     default boolean isSkippable() {
         return false;
     }
diff --git a/src/main/java/net/minecraft/network/protocol/game/ClientboundContainerSetContentPacket.java b/src/main/java/net/minecraft/network/protocol/game/ClientboundContainerSetContentPacket.java
index 0e076173033278587df2b5dfbd01cc9005651eb5..dbd8b9b09b82c1b75e8be9dc7416d9f0863c8c87 100644
--- a/src/main/java/net/minecraft/network/protocol/game/ClientboundContainerSetContentPacket.java
+++ b/src/main/java/net/minecraft/network/protocol/game/ClientboundContainerSetContentPacket.java
@@ -31,6 +31,16 @@ public class ClientboundContainerSetContentPacket implements Packet<ClientGamePa
         this.carriedItem = buf.readItem();
     }
 
+    // Paper start
+    @Override
+    public boolean packetTooLarge(net.minecraft.network.Connection manager) {
+        for (int i = 0 ; i < this.items.size() ; i++) {
+            manager.send(new ClientboundContainerSetSlotPacket(this.containerId, this.stateId, i, this.items.get(i)));
+        }
+        return true;
+    }
+    // Paper end
+
     @Override
     public void write(FriendlyByteBuf buf) {
         buf.writeByte(this.containerId);
diff --git a/src/main/java/net/minecraft/network/protocol/game/ClientboundLevelChunkPacketData.java b/src/main/java/net/minecraft/network/protocol/game/ClientboundLevelChunkPacketData.java
index 932cca4d957c1fc212b7a514ea23e8dc7ab5b9d9..f47eeb70661661610ef1a96dd9da67785825c126 100644
--- a/src/main/java/net/minecraft/network/protocol/game/ClientboundLevelChunkPacketData.java
+++ b/src/main/java/net/minecraft/network/protocol/game/ClientboundLevelChunkPacketData.java
@@ -50,7 +50,7 @@ public class ClientboundLevelChunkPacketData {
             throw new RuntimeException("Can't read heightmap in packet for [" + x + ", " + z + "]");
         } else {
             int i = buf.readVarInt();
-            if (i > 2097152) {
+            if (i > 2097152) { // Paper - diff on change - if this changes, update PacketEncoder
                 throw new RuntimeException("Chunk Packet trying to allocate too much memory on read.");
             } else {
                 this.buffer = new byte[i];