Paper/patches/server/0300-Limit-Client-Sign-length-more.patch
Spottedleaf 01a13871de
Rewrite chunk system (#8177)
Patch documentation to come

Issues with the old system that are fixed now:
- World generation does not scale with cpu cores effectively.
- Relies on the main thread for scheduling and maintaining chunk state, dropping chunk load/generate rates at lower tps.
- Unreliable prioritisation of chunk gen/load calls that block the main thread.
- Shutdown logic is utterly unreliable, as it has to wait for all chunks to unload - is it guaranteed that the chunk system is in a state on shutdown that it can reliably do this? Watchdog shutdown also typically failed due to thread checks, which is now resolved.
- Saving of data is not unified (i.e can save chunk data without saving entity data, poses problems for desync if shutdown is really abnormal.
- Entities are not loaded with chunks. This caused quite a bit of headache for Chunk#getEntities API, but now the new chunk system loads entities with chunks so that they are ready whenever the chunk loads in. Effectively brings the behavior back to 1.16 era, but still storing entities in their own separate regionfiles.

The above list is not complete. The patch documentation will complete it.

New chunk system hard relies on starlight and dataconverter, and most importantly the new concurrent utilities in ConcurrentUtil.

Some of the old async chunk i/o interface (i.e the old file io thread reroutes _some_ calls to the new file io thread) is kept for plugin compat reasons. It will be removed in the next major version of minecraft.

The old legacy chunk system patches have been moved to the removed folder in case we need them again.
2022-09-26 01:02:51 -07:00

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From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Aikar <aikar@aikar.co>
Date: Wed, 27 Feb 2019 22:18:40 -0500
Subject: [PATCH] Limit Client Sign length more
modified clients can send more data from the client
to the server and it would get stored on the sign as sent.
Mojang has a limit of 384 which is much higher than reasonable.
the client can barely render around 16 characters as-is, but formatting
codes can get it to be more than 16 actual length.
Set a limit of 80 which should give an average of 16 characters 2
sets of legacy formatting codes which should be plenty for all uses.
This does not strip any existing data from the NBT as plugins
may use this for storing data out of the rendered area.
it only impacts data sent from the client.
Set -DPaper.maxSignLength=XX to change limit or -1 to disable
diff --git a/src/main/java/net/minecraft/server/network/ServerGamePacketListenerImpl.java b/src/main/java/net/minecraft/server/network/ServerGamePacketListenerImpl.java
index ac5f70ee86cc5a01b046e8e610434742448e3919..1c1ba459535296e029a8d39a5f78d60eb29cdb71 100644
--- a/src/main/java/net/minecraft/server/network/ServerGamePacketListenerImpl.java
+++ b/src/main/java/net/minecraft/server/network/ServerGamePacketListenerImpl.java
@@ -296,6 +296,7 @@ public class ServerGamePacketListenerImpl implements ServerPlayerConnection, Tic
private final LastSeenMessagesValidator lastSeenMessagesValidator;
private final FutureChain chatMessageChain;
private static final long KEEPALIVE_LIMIT = Long.getLong("paper.playerconnection.keepalive", 30) * 1000; // Paper - provide property to set keepalive limit
+ private static final int MAX_SIGN_LINE_LENGTH = Integer.getInteger("Paper.maxSignLength", 80); // Paper
public ServerGamePacketListenerImpl(MinecraftServer server, Connection connection, ServerPlayer player) {
this.lastChatTimeStamp = new AtomicReference(Instant.EPOCH);
@@ -3296,7 +3297,19 @@ public class ServerGamePacketListenerImpl implements ServerPlayerConnection, Tic
@Override
public void handleSignUpdate(ServerboundSignUpdatePacket packet) {
- List<String> list = (List) Stream.of(packet.getLines()).map(ChatFormatting::stripFormatting).collect(Collectors.toList());
+ // Paper start - cap line length - modified clients can send longer data than normal
+ String[] lines = packet.getLines();
+ for (int i = 0; i < lines.length; ++i) {
+ if (MAX_SIGN_LINE_LENGTH > 0 && lines[i].length() > MAX_SIGN_LINE_LENGTH) {
+ // This handles multibyte characters as 1
+ int offset = lines[i].codePoints().limit(MAX_SIGN_LINE_LENGTH).map(Character::charCount).sum();
+ if (offset < lines[i].length()) {
+ lines[i] = lines[i].substring(0, offset); // this will break any filtering, but filtering is NYI as of 1.17
+ }
+ }
+ }
+ List<String> list = (List) Stream.of(lines).map(ChatFormatting::stripFormatting).collect(Collectors.toList());
+ // Paper end
this.filterTextPacket(list).thenAcceptAsync((list1) -> {
this.updateSignText(packet, list1);