From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001 From: Aikar 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 3cad1ccf74b078496db5dfe9d0bb55636c059634..ea267989024ac8546584231f439f1d5c8da6c6ea 100644 --- a/src/main/java/net/minecraft/server/network/ServerGamePacketListenerImpl.java +++ b/src/main/java/net/minecraft/server/network/ServerGamePacketListenerImpl.java @@ -288,6 +288,7 @@ public class ServerGamePacketListenerImpl extends ServerCommonPacketListenerImpl private final MessageSignatureCache messageSignatureCache; private final FutureChain chatMessageChain; private boolean waitingForSwitchToConfig; + private static final int MAX_SIGN_LINE_LENGTH = Integer.getInteger("Paper.maxSignLength", 80); // Paper public ServerGamePacketListenerImpl(MinecraftServer server, Connection connection, ServerPlayer player, CommonListenerCookie clientData) { super(server, connection, clientData, player); // CraftBukkit @@ -3051,7 +3052,19 @@ public class ServerGamePacketListenerImpl extends ServerCommonPacketListenerImpl @Override public void handleSignUpdate(ServerboundSignUpdatePacket packet) { - List 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 list = (List) Stream.of(lines).map(ChatFormatting::stripFormatting).collect(Collectors.toList()); + // Paper end this.filterTextPacket(list).thenAcceptAsync((list1) -> { this.updateSignText(packet, list1);