More conservative filtering

this now only drops consecutive packets with identical buffers, and only when instructed to.
This is good enough to fix both right- and left-click spam bugs as of 1.21.100.

src/network/FilterNoisyPacketException.php

@@ -0,0 +1,31 @@
+<?php
+
+/*
+ *
+ *  ____            _        _   __  __ _                  __  __ ____
+ * |  _ \ ___   ___| | _____| |_|  \/  (_)_ __   ___      |  \/  |  _ \
+ * | |_) / _ \ / __| |/ / _ \ __| |\/| | | '_ \ / _ \_____| |\/| | |_) |
+ * |  __/ (_) | (__|   <  __/ |_| |  | | | | | |  __/_____| |  | |  __/
+ * |_|   \___/ \___|_|\_\___|\__|_|  |_|_|_| |_|\___|     |_|  |_|_|
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * @author PocketMine Team
+ * @link http://www.pocketmine.net/
+ *
+ *
+ */
+
+declare(strict_types=1);
+
+namespace pocketmine\network;
+
+/**
+ * Thrown by packet handlers to instruct network sessions to drop repeated packets.
+ */
+final class FilterNoisyPacketException extends \RuntimeException{
+
+}

src/network/mcpe/NetworkSession.php

@@ -36,6 +36,7 @@ use pocketmine\lang\Translatable;
 use pocketmine\math\Vector3;
 use pocketmine\nbt\tag\CompoundTag;
 use pocketmine\nbt\tag\StringTag;
+use pocketmine\network\FilterNoisyPacketException;
 use pocketmine\network\mcpe\cache\ChunkCache;
 use pocketmine\network\mcpe\compression\CompressBatchPromise;
 use pocketmine\network\mcpe\compression\Compressor;
@@ -146,6 +147,8 @@ class NetworkSession{
 	private const INCOMING_GAME_PACKETS_PER_TICK = 2;
 	private const INCOMING_GAME_PACKETS_BUFFER_TICKS = 100;
 
+	private const INCOMING_PACKET_BATCH_HARD_LIMIT = 300;
+
 	private PacketRateLimiter $packetBatchLimiter;
 	private PacketRateLimiter $gamePacketLimiter;
 
@@ -387,18 +390,15 @@ class NetworkSession{
 	}
 
 	private function checkRepeatedPacketFilter(string $buffer) : bool{
-		//TODO: would be great if we didn't repeat reading the ID inside PacketPool
-		$dummy = 0;
-		$packetId = Binary::readUnsignedVarInt($buffer, $dummy);
-
-		if(isset($this->repeatedPacketFilters[$packetId])){
-			if($buffer === $this->repeatedPacketFilters[$packetId]){
-				$this->repeatedPacketFilterStats[$packetId]++;
+		if($buffer === $this->noisyPacketBuffer){
+			$this->noisyPacketsDropped++;
 			return true;
 		}
-
-			$this->repeatedPacketFilters[$packetId] = $buffer;
-		}
+		//stop filtering once we see a packet with a different buffer
+		//this won't be any good for interleaved spammy packets, but we haven't seen any of those so far, and this
+		//is the simplest and most conservative filter we can do
+		$this->noisyPacketBuffer = "";
+		$this->noisyPacketsDropped = 0;
 
 		return false;
 	}
@@ -453,9 +453,17 @@ class NetworkSession{
 				$decompressed = $payload;
 			}
 
+			$count = 0;
 			try{
 				$stream = new BinaryStream($decompressed);
 				foreach(PacketBatch::decodeRaw($stream) as $buffer){
+					if(++$count >= self::INCOMING_PACKET_BATCH_HARD_LIMIT){
+						//this should be well more than enough; under normal conditions the game packet rate limiter
+						//will kick in well before this. This is only here to make sure we can't get huge batches of
+						//noisy packets to bog down the server, since those aren't counted by the regular limiter.
+						throw new PacketHandlingException("Reached hard limit of " . self::INCOMING_PACKET_BATCH_HARD_LIMIT . " per batch packet");
+					}
+
 					if($this->checkRepeatedPacketFilter($buffer)){
 						continue;
 					}
@@ -471,6 +479,8 @@ class NetworkSession{
 					}catch(PacketHandlingException $e){
 						$this->logger->debug($packet->getName() . ": " . base64_encode($buffer));
 						throw PacketHandlingException::wrap($e, "Error processing " . $packet->getName());
+					}catch(FilterNoisyPacketException){
+						$this->noisyPacketBuffer = $buffer;
 					}
 					if(!$this->isConnected()){
 						//handling this packet may have caused a disconnection

src/network/mcpe/handler/InGamePacketHandler.php

@@ -44,6 +44,7 @@ use pocketmine\math\Facing;
 use pocketmine\math\Vector3;
 use pocketmine\nbt\tag\CompoundTag;
 use pocketmine\nbt\tag\StringTag;
+use pocketmine\network\FilterNoisyPacketException;
 use pocketmine\network\mcpe\InventoryManager;
 use pocketmine\network\mcpe\NetworkSession;
 use pocketmine\network\mcpe\protocol\ActorEventPacket;
@@ -473,6 +474,22 @@ class InGamePacketHandler extends PacketHandler{
 
 		switch($data->getActionType()){
 			case UseItemTransactionData::ACTION_CLICK_BLOCK:
+				//TODO: start hack for client spam bug
+				$clickPos = $data->getClickPosition();
+				$spamBug = ($this->lastRightClickData !== null &&
+					microtime(true) - $this->lastRightClickTime < 0.1 && //100ms
+					$this->lastRightClickData->getPlayerPosition()->distanceSquared($data->getPlayerPosition()) < 0.00001 &&
+					$this->lastRightClickData->getBlockPosition()->equals($data->getBlockPosition()) &&
+					$this->lastRightClickData->getClickPosition()->distanceSquared($clickPos) < 0.00001 //signature spam bug has 0 distance, but allow some error
+				);
+				//get rid of continued spam if the player clicks and holds right-click
+				$this->lastRightClickData = $data;
+				$this->lastRightClickTime = microtime(true);
+				if($spamBug){
+					throw new FilterNoisyPacketException();
+				}
+				//TODO: end hack for client spam bug
+
 				self::validateFacing($data->getFace());
 
 				$blockPos = $data->getBlockPosition();
@@ -724,7 +741,9 @@ class InGamePacketHandler extends PacketHandler{
 	}
 
 	public function handleAnimate(AnimatePacket $packet) : bool{
-		return true; //Not used
+		//this spams harder than a firehose on left click if "Improved Input Response" is enabled, and we don't even
+		//use it anyway :<
+		throw new FilterNoisyPacketException();
 	}
 
 	public function handleContainerClose(ContainerClosePacket $packet) : bool{