InGamePacketHandler.php

<?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\mcpe\handler;
 
use pocketmine\block\BaseSign;
use pocketmine\block\Lectern;
use pocketmine\block\tile\Sign;
use pocketmine\block\utils\SignText;
use pocketmine\entity\Attribute;
use pocketmine\entity\InvalidSkinException;
use pocketmine\event\player\PlayerEditBookEvent;
use pocketmine\inventory\transaction\action\DropItemAction;
use pocketmine\inventory\transaction\InventoryTransaction;
use pocketmine\inventory\transaction\TransactionBuilder;
use pocketmine\inventory\transaction\TransactionCancelledException;
use pocketmine\inventory\transaction\TransactionValidationException;
use pocketmine\item\VanillaItems;
use pocketmine\item\WritableBook;
use pocketmine\item\WritableBookPage;
use pocketmine\item\WrittenBook;
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\convert\ItemTranslator;
use pocketmine\network\mcpe\InventoryManager;
use pocketmine\network\mcpe\NetworkSession;
use pocketmine\network\mcpe\protocol\ActorEventPacket;
use pocketmine\network\mcpe\protocol\ActorPickRequestPacket;
use pocketmine\network\mcpe\protocol\AnimatePacket;
use pocketmine\network\mcpe\protocol\BlockActorDataPacket;
use pocketmine\network\mcpe\protocol\BlockPickRequestPacket;
use pocketmine\network\mcpe\protocol\BookEditPacket;
use pocketmine\network\mcpe\protocol\CommandRequestPacket;
use pocketmine\network\mcpe\protocol\ContainerClosePacket;
use pocketmine\network\mcpe\protocol\EmotePacket;
use pocketmine\network\mcpe\protocol\InteractPacket;
use pocketmine\network\mcpe\protocol\InventoryTransactionPacket;
use pocketmine\network\mcpe\protocol\ItemStackRequestPacket;
use pocketmine\network\mcpe\protocol\ItemStackResponsePacket;
use pocketmine\network\mcpe\protocol\LecternUpdatePacket;
use pocketmine\network\mcpe\protocol\LevelSoundEventPacket;
use pocketmine\network\mcpe\protocol\MobArmorEquipmentPacket;
use pocketmine\network\mcpe\protocol\MobEquipmentPacket;
use pocketmine\network\mcpe\protocol\ModalFormResponsePacket;
use pocketmine\network\mcpe\protocol\MovePlayerPacket;
use pocketmine\network\mcpe\protocol\NetworkStackLatencyPacket;
use pocketmine\network\mcpe\protocol\PlayerActionPacket;
use pocketmine\network\mcpe\protocol\PlayerAuthInputPacket;
use pocketmine\network\mcpe\protocol\PlayerHotbarPacket;
use pocketmine\network\mcpe\protocol\PlayerSkinPacket;
use pocketmine\network\mcpe\protocol\RequestChunkRadiusPacket;
use pocketmine\network\mcpe\protocol\serializer\BitSet;
use pocketmine\network\mcpe\protocol\SetActorMotionPacket;
use pocketmine\network\mcpe\protocol\SetPlayerGameTypePacket;
use pocketmine\network\mcpe\protocol\SpawnExperienceOrbPacket;
use pocketmine\network\mcpe\protocol\TextPacket;
use pocketmine\network\mcpe\protocol\types\BlockPosition;
use pocketmine\network\mcpe\protocol\types\inventory\ContainerIds;
use pocketmine\network\mcpe\protocol\types\inventory\MismatchTransactionData;
use pocketmine\network\mcpe\protocol\types\inventory\NetworkInventoryAction;
use pocketmine\network\mcpe\protocol\types\inventory\NormalTransactionData;
use pocketmine\network\mcpe\protocol\types\inventory\PredictedResult;
use pocketmine\network\mcpe\protocol\types\inventory\ReleaseItemTransactionData;
use pocketmine\network\mcpe\protocol\types\inventory\stackrequest\ItemStackRequest;
use pocketmine\network\mcpe\protocol\types\inventory\stackresponse\ItemStackResponse;
use pocketmine\network\mcpe\protocol\types\inventory\UseItemOnEntityTransactionData;
use pocketmine\network\mcpe\protocol\types\inventory\UseItemTransactionData;
use pocketmine\network\mcpe\protocol\types\PlayerAction;
use pocketmine\network\mcpe\protocol\types\PlayerAuthInputFlags;
use pocketmine\network\mcpe\protocol\types\PlayerBlockActionStopBreak;
use pocketmine\network\mcpe\protocol\types\PlayerBlockActionWithBlockInfo;
use pocketmine\network\PacketHandlingException;
use pocketmine\player\Player;
use pocketmine\utils\AssumptionFailedError;
use pocketmine\utils\Limits;
use pocketmine\utils\TextFormat;
use pocketmine\utils\Utils;
use pocketmine\world\format\Chunk;
use function array_push;
use function count;
use function fmod;
use function get_debug_type;
use function implode;
use function in_array;
use function is_infinite;
use function is_nan;
use function json_decode;
use function max;
use function mb_strlen;
use function microtime;
use function sprintf;
use function str_starts_with;
use function strlen;
use const JSON_THROW_ON_ERROR;
 
#[SilentDiscard(ActorEventPacket::class, comment: "Not needed")]
#[SilentDiscard(LevelSoundEventPacket::class, comment: "Sounds are always handled server side")]
#[SilentDiscard(MobArmorEquipmentPacket::class, comment: "Not needed")]
#[SilentDiscard(MovePlayerPacket::class, comment: "Not needed, noisy debug when landing on ground")]
#[SilentDiscard(NetworkStackLatencyPacket::class, comment: "Not used, noisy debug")]
#[SilentDiscard(PlayerHotbarPacket::class, comment: "Not needed")]
#[SilentDiscard(SetActorMotionPacket::class, comment: "Not needed, erroneously sent by client when in a vehicle")]
#[SilentDiscard(SpawnExperienceOrbPacket::class, comment: "XP drops should be server-calculated")]
class InGamePacketHandler extends PacketHandler{
    private const MAX_FORM_RESPONSE_SIZE = 10 * 1024; //10 KiB should be more than enough
    private const MAX_FORM_RESPONSE_DEPTH = 2; //modal/simple will be 1, custom forms 2 - they will never contain anything other than string|int|float|bool|null
 
    //TODO: The client-side per-page character limit is inconsistent for non-ASCII text,
    //allowing input beyond 256 chars. Use a slightly higher bounded soft limit to
    //prevent rejected edits while still mitigating book-bomb attacks
    private const PAGE_LENGTH_SOFT_LIMIT_CHARS = 512;
 
    protected float $lastRightClickTime = 0.0;
    protected ?UseItemTransactionData $lastRightClickData = null;
 
    protected ?Vector3 $lastPlayerAuthInputPosition = null;
    protected ?float $lastPlayerAuthInputYaw = null;
    protected ?float $lastPlayerAuthInputPitch = null;
    protected ?BitSet $lastPlayerAuthInputFlags = null;
 
    protected ?BlockPosition $lastBlockAttacked = null;
 
    public bool $forceMoveSync = false;
 
    protected ?string $lastRequestedFullSkinId = null;
 
    public function __construct(
        private Player $player,
        private NetworkSession $session,
        private InventoryManager $inventoryManager
    ){}
 
    public function handleText(TextPacket $packet) : bool{
        if($packet->type === TextPacket::TYPE_CHAT){
            return $this->player->chat($packet->message);
        }
 
        return false;
    }
 
    private function resolveOnOffInputFlags(BitSet $inputFlags, int $startFlag, int $stopFlag) : ?bool{
        $enabled = $inputFlags->get($startFlag);
        $disabled = $inputFlags->get($stopFlag);
        if($enabled !== $disabled){
            return $enabled;
        }
        //neither flag was set, or both were set
        return null;
    }
 
    public function handlePlayerAuthInput(PlayerAuthInputPacket $packet) : bool{
        $rawPos = $packet->getPosition();
        $rawYaw = $packet->getYaw();
        $rawPitch = $packet->getPitch();
        foreach([$rawPos->x, $rawPos->y, $rawPos->z, $rawYaw, $packet->getHeadYaw(), $rawPitch] as $float){
            if(is_infinite($float) || is_nan($float)){
                $this->session->getLogger()->debug("Invalid movement received, contains NAN/INF components");
                return false;
            }
        }
 
        if($rawYaw !== $this->lastPlayerAuthInputYaw || $rawPitch !== $this->lastPlayerAuthInputPitch){
            $this->lastPlayerAuthInputYaw = $rawYaw;
            $this->lastPlayerAuthInputPitch = $rawPitch;
 
            $yaw = fmod($rawYaw, 360);
            $pitch = fmod($rawPitch, 360);
            if($yaw < 0){
                $yaw += 360;
            }
 
            $this->player->setRotation($yaw, $pitch);
        }
 
        $hasMoved = $this->lastPlayerAuthInputPosition === null || !$this->lastPlayerAuthInputPosition->equals($rawPos);
        $newPos = $rawPos->subtract(0, 1.62, 0)->round(4);
 
        if($this->forceMoveSync && $hasMoved){
            $curPos = $this->player->getLocation();
 
            if($newPos->distanceSquared($curPos) > 1){  //Tolerate up to 1 block to avoid problems with client-sided physics when spawning in blocks
                $this->session->getLogger()->debug("Got outdated pre-teleport movement, received " . $newPos . ", expected " . $curPos);
                //Still getting movements from before teleport, ignore them
                return true;
            }
 
            // Once we get a movement within a reasonable distance, treat it as a teleport ACK and remove position lock
            $this->forceMoveSync = false;
        }
 
        $inputFlags = $packet->getInputFlags();
        if($this->lastPlayerAuthInputFlags === null || !$inputFlags->equals($this->lastPlayerAuthInputFlags)){
            $this->lastPlayerAuthInputFlags = $inputFlags;
 
            $sneakPressed = $inputFlags->get(PlayerAuthInputFlags::SNEAKING);
 
            $sneaking = $this->resolveOnOffInputFlags($inputFlags, PlayerAuthInputFlags::START_SNEAKING, PlayerAuthInputFlags::STOP_SNEAKING);
            $sprinting = $this->resolveOnOffInputFlags($inputFlags, PlayerAuthInputFlags::START_SPRINTING, PlayerAuthInputFlags::STOP_SPRINTING);
            $swimming = $this->resolveOnOffInputFlags($inputFlags, PlayerAuthInputFlags::START_SWIMMING, PlayerAuthInputFlags::STOP_SWIMMING);
            $gliding = $this->resolveOnOffInputFlags($inputFlags, PlayerAuthInputFlags::START_GLIDING, PlayerAuthInputFlags::STOP_GLIDING);
            $flying = $this->resolveOnOffInputFlags($inputFlags, PlayerAuthInputFlags::START_FLYING, PlayerAuthInputFlags::STOP_FLYING);
            $mismatch =
                (!$this->player->toggleSneak($sneaking ?? $this->player->isSneaking(), $sneakPressed)) |
                ($sprinting !== null && !$this->player->toggleSprint($sprinting)) |
                ($swimming !== null && !$this->player->toggleSwim($swimming)) |
                ($gliding !== null && !$this->player->toggleGlide($gliding)) |
                ($flying !== null && !$this->player->toggleFlight($flying));
            if((bool) $mismatch){
                $this->player->sendData([$this->player]);
            }
 
            if($inputFlags->get(PlayerAuthInputFlags::START_JUMPING)){
                $this->player->jump();
            }
            if($inputFlags->get(PlayerAuthInputFlags::MISSED_SWING)){
                $this->player->missSwing();
            }
        }
 
        if(!$this->forceMoveSync && $hasMoved){
            $this->lastPlayerAuthInputPosition = $rawPos;
            //TODO: this packet has WAYYYYY more useful information that we're not using
            $this->player->handleMovement($newPos);
        }
 
        $packetHandled = true;
 
        $useItemTransaction = $packet->getItemInteractionData();
        if($useItemTransaction !== null){
            if(count($useItemTransaction->getTransactionData()->getActions()) > 100){
                throw new PacketHandlingException("Too many actions in item use transaction");
            }
 
            $this->inventoryManager->setCurrentItemStackRequestId($useItemTransaction->getRequestId());
            $this->inventoryManager->addRawPredictedSlotChanges($useItemTransaction->getTransactionData()->getActions());
            if(!$this->handleUseItemTransaction($useItemTransaction->getTransactionData())){
                $packetHandled = false;
                $this->session->getLogger()->debug("Unhandled transaction in PlayerAuthInputPacket (type " . $useItemTransaction->getTransactionData()->getActionType() . ")");
            }else{
                $this->inventoryManager->syncMismatchedPredictedSlotChanges();
            }
            $this->inventoryManager->setCurrentItemStackRequestId(null);
        }
 
        $itemStackRequest = $packet->getItemStackRequest();
        $itemStackResponseBuilder = $itemStackRequest !== null ? $this->handleSingleItemStackRequest($itemStackRequest) : null;
 
        //itemstack request or transaction may set predictions for the outcome of these actions, so these need to be
        //processed last
        $blockActions = $packet->getBlockActions();
        if($blockActions !== null){
            if(count($blockActions) > 100){
                throw new PacketHandlingException("Too many block actions in PlayerAuthInputPacket");
            }
            foreach(Utils::promoteKeys($blockActions) as $k => $blockAction){
                $actionHandled = false;
                if($blockAction instanceof PlayerBlockActionStopBreak){
                    $actionHandled = $this->handlePlayerActionFromData($blockAction->getActionType(), new BlockPosition(0, 0, 0), Facing::DOWN);
                }elseif($blockAction instanceof PlayerBlockActionWithBlockInfo){
                    $actionHandled = $this->handlePlayerActionFromData($blockAction->getActionType(), $blockAction->getBlockPosition(), $blockAction->getFace());
                }
 
                if(!$actionHandled){
                    $packetHandled = false;
                    $this->session->getLogger()->debug("Unhandled player block action at offset $k in PlayerAuthInputPacket");
                }
            }
        }
 
        if($itemStackRequest !== null){
            $itemStackResponse = $itemStackResponseBuilder?->build() ?? new ItemStackResponse(ItemStackResponse::RESULT_ERROR, $itemStackRequest->getRequestId());
            $this->session->sendDataPacket(ItemStackResponsePacket::create([$itemStackResponse]));
        }
 
        return $packetHandled;
    }
 
    public function handleInventoryTransaction(InventoryTransactionPacket $packet) : bool{
        $result = true;
 
        if(count($packet->trData->getActions()) > 50){
            throw new PacketHandlingException("Too many actions in inventory transaction");
        }
        if($packet->requestChangedSlots !== null && count($packet->requestChangedSlots) > 10){
            throw new PacketHandlingException("Too many slot sync requests in inventory transaction");
        }
 
        $this->inventoryManager->setCurrentItemStackRequestId($packet->requestId);
        $this->inventoryManager->addRawPredictedSlotChanges($packet->trData->getActions());
 
        if($packet->trData instanceof NormalTransactionData){
            $result = $this->handleNormalTransaction($packet->trData, $packet->requestId);
        }elseif($packet->trData instanceof MismatchTransactionData){
            $this->session->getLogger()->debug("Mismatch transaction received");
            $this->inventoryManager->requestSyncAll();
            $result = true;
        }elseif($packet->trData instanceof UseItemTransactionData){
            $result = $this->handleUseItemTransaction($packet->trData);
        }elseif($packet->trData instanceof UseItemOnEntityTransactionData){
            $result = $this->handleUseItemOnEntityTransaction($packet->trData);
        }elseif($packet->trData instanceof ReleaseItemTransactionData){
            $result = $this->handleReleaseItemTransaction($packet->trData);
        }
 
        $this->inventoryManager->syncMismatchedPredictedSlotChanges();
 
        //requestChangedSlots asks the server to always send out the contents of the specified slots, even if they
        //haven't changed. Handling these is necessary to ensure the client inventory stays in sync if the server
        //rejects the transaction. The most common example of this is equipping armor by right-click, which doesn't send
        //a legacy prediction action for the destination armor slot.
        if($packet->requestChangedSlots !== null){
            foreach($packet->requestChangedSlots as $containerInfo){
                foreach($containerInfo->getChangedSlotIndexes() as $netSlot){
                    [$windowId, $slot] = ItemStackContainerIdTranslator::translate($containerInfo->getContainerId(), $this->inventoryManager->getCurrentWindowId(), $netSlot);
                    $inventoryAndSlot = $this->inventoryManager->locateWindowAndSlot($windowId, $slot);
                    if($inventoryAndSlot !== null){ //trigger the normal slot sync logic
                        $this->inventoryManager->onSlotChange($inventoryAndSlot[0], $inventoryAndSlot[1]);
                    }
                }
            }
        }
 
        $this->inventoryManager->setCurrentItemStackRequestId(null);
        return $result;
    }
 
    private function executeInventoryTransaction(InventoryTransaction $transaction, int $requestId) : bool{
        $this->player->setUsingItem(false);
 
        $this->inventoryManager->setCurrentItemStackRequestId($requestId);
        $this->inventoryManager->addTransactionPredictedSlotChanges($transaction);
        try{
            $transaction->execute();
        }catch(TransactionValidationException $e){
            $this->inventoryManager->requestSyncAll();
            $logger = $this->session->getLogger();
            $logger->debug("Invalid inventory transaction $requestId: " . $e->getMessage());
 
            return false;
        }catch(TransactionCancelledException){
            $this->session->getLogger()->debug("Inventory transaction $requestId cancelled by a plugin");
 
            return false;
        }finally{
            $this->inventoryManager->syncMismatchedPredictedSlotChanges();
            $this->inventoryManager->setCurrentItemStackRequestId(null);
        }
 
        return true;
    }
 
    private function handleNormalTransaction(NormalTransactionData $data, int $itemStackRequestId) : bool{
        //When the ItemStackRequest system is used, this transaction type is used for dropping items by pressing Q.
        //I don't know why they don't just use ItemStackRequest for that too, which already supports dropping items by
        //clicking them outside an open inventory menu, but for now it is what it is.
        //Fortunately, this means we can be much stricter about the validation criteria.
 
        $actionCount = count($data->getActions());
        if($actionCount > 2){
            if($actionCount > 5){
                throw new PacketHandlingException("Too many actions ($actionCount) in normal inventory transaction");
            }
 
            //Due to a bug in the game, this transaction type is still sent when a player edits a book. We don't need
            //these transactions for editing books, since we have BookEditPacket, so we can just ignore them.
            $this->session->getLogger()->debug("Ignoring normal inventory transaction with $actionCount actions (drop-item should have exactly 2 actions)");
            return false;
        }
 
        $sourceSlot = null;
        $clientItemStack = null;
        $droppedCount = null;
 
        foreach($data->getActions() as $networkInventoryAction){
            if($networkInventoryAction->sourceType === NetworkInventoryAction::SOURCE_WORLD && $networkInventoryAction->inventorySlot === NetworkInventoryAction::ACTION_MAGIC_SLOT_DROP_ITEM){
                $droppedCount = $networkInventoryAction->newItem->getItemStack()->getCount();
                if($droppedCount <= 0){
                    throw new PacketHandlingException("Expected positive count for dropped item");
                }
            }elseif($networkInventoryAction->sourceType === NetworkInventoryAction::SOURCE_CONTAINER && $networkInventoryAction->windowId === ContainerIds::INVENTORY){
                //mobile players can drop an item from a non-selected hotbar slot
                $sourceSlot = $networkInventoryAction->inventorySlot;
                $clientItemStack = $networkInventoryAction->oldItem->getItemStack();
            }else{
                $this->session->getLogger()->debug("Unexpected inventory action type $networkInventoryAction->sourceType in drop item transaction");
                return false;
            }
        }
        if($sourceSlot === null || $clientItemStack === null || $droppedCount === null){
            $this->session->getLogger()->debug("Missing information in drop item transaction, need source slot, client item stack and dropped count");
            return false;
        }
 
        $inventory = $this->player->getInventory();
 
        if(!$inventory->slotExists($sourceSlot)){
            return false; //TODO: size desync??
        }
 
        $sourceSlotItem = $inventory->getItem($sourceSlot);
        if($sourceSlotItem->getCount() < $droppedCount){
            return false;
        }
        $serverItemStack = $this->session->getTypeConverter()->coreItemStackToNet($sourceSlotItem);
        //Sadly we don't have itemstack IDs here, so we have to compare the basic item properties to ensure that we're
        //dropping the item the client expects (inventory might be out of sync with the client).
        if(
            $serverItemStack->getId() !== $clientItemStack->getId() ||
            $serverItemStack->getMeta() !== $clientItemStack->getMeta() ||
            $serverItemStack->getCount() !== $clientItemStack->getCount() ||
            $serverItemStack->getBlockRuntimeId() !== $clientItemStack->getBlockRuntimeId()
            //Raw extraData may not match because of TAG_Compound key ordering differences, and decoding it to compare
            //is costly. Assume that we're in sync if id+meta+count+runtimeId match.
            //NB: Make sure $clientItemStack isn't used to create the dropped item, as that would allow the client
            //to change the item NBT since we're not validating it.
        ){
            return false;
        }
 
        //this modifies $sourceSlotItem
        $droppedItem = $sourceSlotItem->pop($droppedCount);
 
        $builder = new TransactionBuilder();
        $builder->getInventory($inventory)->setItem($sourceSlot, $sourceSlotItem);
        $builder->addAction(new DropItemAction($droppedItem));
 
        $transaction = new InventoryTransaction($this->player, $builder->generateActions());
        return $this->executeInventoryTransaction($transaction, $itemStackRequestId);
    }
 
    private function handleUseItemTransaction(UseItemTransactionData $data) : bool{
        $this->player->selectHotbarSlot($data->getHotbarSlot());
 
        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->getFace() === $data->getFace() &&
                    $this->lastRightClickData->getPlayerPosition()->distanceSquared($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();
                $vBlockPos = new Vector3($blockPos->getX(), $blockPos->getY(), $blockPos->getZ());
                $this->player->interactBlock($vBlockPos, $data->getFace(), $clickPos);
                if($data->getClientInteractPrediction() === PredictedResult::SUCCESS){
                    //If the item has an associated blockstate ID, this means it will only place one block.
                    //We can avoid syncing the adjacent blocks of the place position in this case, since that's only
                    //necessary if there might be multiple blocks around the placement location affected.
                    //Adjacents of the clicked block are still always synced, since it's too complicated to figure out
                    //if the client might've predicted something in this case. However, since the clicked block is always
                    //"behind" the placed block, this shouldn't affect bridging or fast placement.
                    //This would be much easier if the client would just tell us which blocks it thinks changed...
                    $syncAdjacentFace = null;
                    if($data->getItemInHand()->getItemStack()->getBlockRuntimeId() === ItemTranslator::NO_BLOCK_RUNTIME_ID){
                        $this->session->getLogger()->debug("Placing held item might place multiple blocks client-side; doing full adjacent sync");
                        $syncAdjacentFace = $data->getFace();
                    }
                    $this->syncBlocksNearby($vBlockPos, $syncAdjacentFace);
                }
                return true;
            case UseItemTransactionData::ACTION_CLICK_AIR:
                if($this->player->isUsingItem()){
                    if(!$this->player->consumeHeldItem()){
                        $hungerAttr = $this->player->getAttributeMap()->get(Attribute::HUNGER) ?? throw new AssumptionFailedError();
                        $hungerAttr->markSynchronized(false);
                    }
                    //TODO: workaround goat horns getting stuck in the "using item" state
                    //this timed-trigger behaviour is also used for other items apart from food
                    //in the future we'll generalise this logic and add proper hooks for it
                    $this->player->setUsingItem(false);
                    return true;
                }
                $this->player->useHeldItem();
                return true;
        }
 
        return false;
    }
 
    private static function validateFacing(int $facing) : void{
        if(!in_array($facing, Facing::ALL, true)){
            throw new PacketHandlingException("Invalid facing value $facing");
        }
    }
 
    private function syncBlocksNearby(Vector3 $blockPos, ?int $face) : void{
        if($blockPos->distanceSquared($this->player->getLocation()) < 10000){
            $blocks = $blockPos->sidesArray();
            if($face !== null){
                $sidePos = $blockPos->getSide($face);
 
                array_push($blocks, ...$sidePos->sidesArray()); //getAllSides() on each of these will include $blockPos and $sidePos because they are next to each other
            }else{
                $blocks[] = $blockPos;
            }
            foreach($this->player->getWorld()->createBlockUpdatePackets($blocks) as $packet){
                $this->session->sendDataPacket($packet);
            }
        }
    }
 
    private function handleUseItemOnEntityTransaction(UseItemOnEntityTransactionData $data) : bool{
        $target = $this->player->getWorld()->getEntity($data->getActorRuntimeId());
        //TODO: HACK! We really shouldn't be keeping disconnected players (and generally flagged-for-despawn entities)
        //in the world's entity table, but changing that is too risky for a hotfix. This workaround will do for now.
        if($target === null || $target->isFlaggedForDespawn()){
            return false;
        }
 
        $this->player->selectHotbarSlot($data->getHotbarSlot());
 
        switch($data->getActionType()){
            case UseItemOnEntityTransactionData::ACTION_INTERACT:
                $this->player->interactEntity($target, $data->getClickPosition());
                return true;
            case UseItemOnEntityTransactionData::ACTION_ATTACK:
                $this->player->attackEntity($target);
                return true;
        }
 
        return false;
    }
 
    private function handleReleaseItemTransaction(ReleaseItemTransactionData $data) : bool{
        $this->player->selectHotbarSlot($data->getHotbarSlot());
 
        if($data->getActionType() === ReleaseItemTransactionData::ACTION_RELEASE){
            $this->player->releaseHeldItem();
            return true;
        }
 
        return false;
    }
 
    private function handleSingleItemStackRequest(ItemStackRequest $request) : ?ItemStackResponseBuilder{
        if(count($request->getActions()) > 60){
            //recipe book auto crafting can affect all slots of the inventory when consuming inputs or producing outputs
            //this means there could be as many as 50 CraftingConsumeInput actions or Place (taking the result) actions
            //in a single request (there are certain ways items can be arranged which will result in the same stack
            //being taken from multiple times, but this is behaviour with a calculable limit)
            //this means there SHOULD be AT MOST 53 actions in a single request, but 60 is a nice round number.
            //n64Stacks = ?
            //n1Stacks = 45 - n64Stacks
            //nItemsRequiredFor1Craft = 9
            //nResults = floor((n1Stacks + (n64Stacks * 64)) / nItemsRequiredFor1Craft)
            //nTakeActionsTotal = floor(64 / nResults) + max(1, 64 % nResults) + ((nResults * nItemsRequiredFor1Craft) - (n64Stacks * 64))
            throw new PacketHandlingException("Too many actions in ItemStackRequest");
        }
        $executor = new ItemStackRequestExecutor($this->player, $this->inventoryManager, $request);
        try{
            $transaction = $executor->generateInventoryTransaction();
            if($transaction !== null){
                $result = $this->executeInventoryTransaction($transaction, $request->getRequestId());
            }else{
                $result = true; //predictions only, just send responses
            }
        }catch(ItemStackRequestProcessException $e){
            $result = false;
            $this->session->getLogger()->debug("ItemStackRequest #" . $request->getRequestId() . " failed: " . $e->getMessage());
            $this->session->getLogger()->debug(implode("\n", Utils::printableExceptionInfo($e)));
            $this->inventoryManager->requestSyncAll();
        }
 
        return $result ? $executor->getItemStackResponseBuilder() : null;
    }
 
    public function handleItemStackRequest(ItemStackRequestPacket $packet) : bool{
        $responses = [];
        if(count($packet->getRequests()) > 80){
            //TODO: we can probably lower this limit, but this will do for now
            throw new PacketHandlingException("Too many requests in ItemStackRequestPacket");
        }
        foreach($packet->getRequests() as $request){
            $responses[] = $this->handleSingleItemStackRequest($request)?->build() ?? new ItemStackResponse(ItemStackResponse::RESULT_ERROR, $request->getRequestId());
        }
 
        $this->session->sendDataPacket(ItemStackResponsePacket::create($responses));
 
        return true;
    }
 
    public function handleMobEquipment(MobEquipmentPacket $packet) : bool{
        if($packet->windowId === ContainerIds::OFFHAND){
            return true; //this happens when we put an item into the offhand
        }
        if($packet->windowId === ContainerIds::INVENTORY){
            $this->inventoryManager->onClientSelectHotbarSlot($packet->hotbarSlot);
            if(!$this->player->selectHotbarSlot($packet->hotbarSlot)){
                $this->inventoryManager->syncSelectedHotbarSlot();
            }
            return true;
        }
        return false;
    }
 
    public function handleInteract(InteractPacket $packet) : bool{
        if($packet->action === InteractPacket::ACTION_MOUSEOVER){
            //TODO HACK: silence useless spam (MCPE 1.8)
            //due to some messy Mojang hacks, it sends this when changing the held item now, which causes us to think
            //the inventory was closed when it wasn't.
            //this is also sent whenever entity metadata updates, which can get really spammy.
            //TODO: implement handling for this where it matters
            return true;
        }
        $target = $this->player->getWorld()->getEntity($packet->targetActorRuntimeId);
        if($target === null){
            return false;
        }
        if($packet->action === InteractPacket::ACTION_OPEN_INVENTORY && $target === $this->player){
            $this->inventoryManager->onClientOpenMainInventory();
            return true;
        }
        return false; //TODO
    }
 
    public function handleBlockPickRequest(BlockPickRequestPacket $packet) : bool{
        return $this->player->pickBlock(new Vector3($packet->blockPosition->getX(), $packet->blockPosition->getY(), $packet->blockPosition->getZ()), $packet->addUserData);
    }
 
    public function handleActorPickRequest(ActorPickRequestPacket $packet) : bool{
        return $this->player->pickEntity($packet->actorUniqueId);
    }
 
    public function handlePlayerAction(PlayerActionPacket $packet) : bool{
        return $this->handlePlayerActionFromData($packet->action, $packet->blockPosition, $packet->face);
    }
 
    private function handlePlayerActionFromData(int $action, BlockPosition $blockPosition, int $face) : bool{
        $pos = new Vector3($blockPosition->getX(), $blockPosition->getY(), $blockPosition->getZ());
 
        switch($action){
            case PlayerAction::START_BREAK:
            case PlayerAction::CONTINUE_DESTROY_BLOCK: //destroy the next block while holding down left click
                self::validateFacing($face);
                if($this->lastBlockAttacked !== null && $blockPosition->equals($this->lastBlockAttacked)){
                    //the client will send CONTINUE_DESTROY_BLOCK for the currently targeted block directly before it
                    //sends PREDICT_DESTROY_BLOCK, but also when it starts to break the block
                    //this seems like a bug in the client and would cause spurious left-click events if we allowed it to
                    //be delivered to the player
                    $this->session->getLogger()->debug("Ignoring PlayerAction $action on $pos because we were already destroying this block");
                    break;
                }
                if(!$this->player->attackBlock($pos, $face)){
                    $this->syncBlocksNearby($pos, $face);
                }
                $this->lastBlockAttacked = $blockPosition;
 
                break;
 
            case PlayerAction::ABORT_BREAK:
            case PlayerAction::STOP_BREAK:
                $this->player->stopBreakBlock($pos);
                $this->lastBlockAttacked = null;
                break;
            case PlayerAction::START_SLEEPING:
                //unused
                break;
            case PlayerAction::STOP_SLEEPING:
                $this->player->stopSleep();
                break;
            case PlayerAction::CRACK_BREAK:
                self::validateFacing($face);
                $this->player->continueBreakBlock($pos, $face);
                $this->lastBlockAttacked = $blockPosition;
                break;
            case PlayerAction::INTERACT_BLOCK: //TODO: ignored (for now)
                break;
            case PlayerAction::CREATIVE_PLAYER_DESTROY_BLOCK:
                //in server auth block breaking, we get PREDICT_DESTROY_BLOCK anyway, so this action is redundant
                break;
            case PlayerAction::PREDICT_DESTROY_BLOCK:
                self::validateFacing($face);
                if(!$this->player->breakBlock($pos)){
                    $this->syncBlocksNearby($pos, $face);
                }
                $this->lastBlockAttacked = null;
                break;
            case PlayerAction::START_ITEM_USE_ON:
            case PlayerAction::STOP_ITEM_USE_ON:
                //TODO: this has no obvious use and seems only used for analytics in vanilla - ignore it
                break;
            default:
                $this->session->getLogger()->debug("Unhandled/unknown player action type " . $action);
                return false;
        }
 
        $this->player->setUsingItem(false);
 
        return true;
    }
 
    public function handleAnimate(AnimatePacket $packet) : bool{
        //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{
        $this->inventoryManager->onClientRemoveWindow($packet->windowId);
        return true;
    }
 
    private function updateSignText(CompoundTag $nbt, string $tagName, bool $frontFace, BaseSign $block, Vector3 $pos) : bool{
        $textTag = $nbt->getTag($tagName);
        if(!$textTag instanceof CompoundTag){
            throw new PacketHandlingException("Invalid tag type " . get_debug_type($textTag) . " for tag \"$tagName\" in sign update data");
        }
        $textBlobTag = $textTag->getTag(Sign::TAG_TEXT_BLOB);
        if(!$textBlobTag instanceof StringTag){
            throw new PacketHandlingException("Invalid tag type " . get_debug_type($textBlobTag) . " for tag \"" . Sign::TAG_TEXT_BLOB . "\" in sign update data");
        }
 
        try{
            $text = SignText::fromBlob($textBlobTag->getValue());
        }catch(\InvalidArgumentException $e){
            throw PacketHandlingException::wrap($e, "Invalid sign text update");
        }
 
        $oldText = $block->getFaceText($frontFace);
        if($text->getLines() === $oldText->getLines()){
            return false;
        }
 
        try{
            if(!$block->updateFaceText($this->player, $frontFace, $text)){
                foreach($this->player->getWorld()->createBlockUpdatePackets([$pos]) as $updatePacket){
                    $this->session->sendDataPacket($updatePacket);
                }
                return false;
            }
            return true;
        }catch(\UnexpectedValueException $e){
            throw PacketHandlingException::wrap($e);
        }
    }
 
    public function handleBlockActorData(BlockActorDataPacket $packet) : bool{
        $pos = new Vector3($packet->blockPosition->getX(), $packet->blockPosition->getY(), $packet->blockPosition->getZ());
        if($pos->distanceSquared($this->player->getLocation()) > 10000){
            return false;
        }
 
        $block = $this->player->getLocation()->getWorld()->getBlock($pos);
        $nbt = $packet->nbt->getRoot();
        if(!($nbt instanceof CompoundTag)) throw new AssumptionFailedError("PHPStan should ensure this is a CompoundTag"); //for phpstorm's benefit
 
        if($block instanceof BaseSign){
            if(!$this->updateSignText($nbt, Sign::TAG_FRONT_TEXT, true, $block, $pos)){
                //only one side can be updated at a time
                $this->updateSignText($nbt, Sign::TAG_BACK_TEXT, false, $block, $pos);
            }
 
            return true;
        }
 
        return false;
    }
 
    public function handleSetPlayerGameType(SetPlayerGameTypePacket $packet) : bool{
        $gameMode = $this->session->getTypeConverter()->protocolGameModeToCore($packet->gamemode);
        if($gameMode !== $this->player->getGamemode()){
            //Set this back to default. TODO: handle this properly
            $this->session->syncGameMode($this->player->getGamemode(), true);
        }
        return true;
    }
 
    public function handleRequestChunkRadius(RequestChunkRadiusPacket $packet) : bool{
        $this->player->setViewDistance($packet->radius);
 
        return true;
    }
 
    public function handleCommandRequest(CommandRequestPacket $packet) : bool{
        if(str_starts_with($packet->command, '/')){
            $this->player->chat($packet->command);
            return true;
        }
        return false;
    }
 
    public function handlePlayerSkin(PlayerSkinPacket $packet) : bool{
        if($packet->skin->getFullSkinId() === $this->lastRequestedFullSkinId){
            //TODO: HACK! In 1.19.60, the client sends its skin back to us if we sent it a skin different from the one
            //it's using. We need to prevent this from causing a feedback loop.
            $this->session->getLogger()->debug("Refused duplicate skin change request");
            return true;
        }
        $this->lastRequestedFullSkinId = $packet->skin->getFullSkinId();
 
        $this->session->getLogger()->debug("Processing skin change request");
        try{
            $skin = $this->session->getTypeConverter()->getSkinAdapter()->fromSkinData($packet->skin);
        }catch(InvalidSkinException $e){
            throw PacketHandlingException::wrap($e, "Invalid skin in PlayerSkinPacket");
        }
        return $this->player->changeSkin($skin, $packet->newSkinName, $packet->oldSkinName);
    }
 
    private function checkBookText(string $string, string $fieldName, int $softLimit, int $hardLimit, bool &$cancel) : string{
        if(strlen($string) > $hardLimit){
            throw new PacketHandlingException(sprintf("Book %s must be at most %d bytes, but have %d bytes", $fieldName, $hardLimit, strlen($string)));
        }
 
        $result = TextFormat::clean($string, false);
        //strlen() is O(1), mb_strlen() is O(n)
        if(strlen($result) > $softLimit * 4 || mb_strlen($result, 'UTF-8') > $softLimit){
            $cancel = true;
            $this->session->getLogger()->debug("Cancelled book edit due to $fieldName exceeded soft limit of $softLimit chars");
        }
 
        return $result;
    }
 
    public function handleBookEdit(BookEditPacket $packet) : bool{
        $inventory = $this->player->getInventory();
        if(!$inventory->slotExists($packet->inventorySlot)){
            return false;
        }
        //TODO: break this up into book API things
        $oldBook = $inventory->getItem($packet->inventorySlot);
        if(!($oldBook instanceof WritableBook)){
            return false;
        }
 
        $newBook = clone $oldBook;
        $modifiedPages = [];
        $cancel = false;
        switch($packet->type){
            case BookEditPacket::TYPE_REPLACE_PAGE:
                $text = self::checkBookText($packet->text, "page text", self::PAGE_LENGTH_SOFT_LIMIT_CHARS, WritableBookPage::PAGE_LENGTH_HARD_LIMIT_BYTES, $cancel);
                if($packet->pageNumber < 0){
                    throw new PacketHandlingException("Page number cannot be negative");
                }
                $newBook->setPageText($packet->pageNumber, $text);
                $modifiedPages[] = $packet->pageNumber;
                break;
            case BookEditPacket::TYPE_ADD_PAGE:
                if(!$newBook->pageExists($packet->pageNumber)){
                    //this may only come before a page which already exists
                    //TODO: the client can send insert-before actions on trailing client-side pages which cause odd behaviour on the server
                    return false;
                }
                $text = self::checkBookText($packet->text, "page text", self::PAGE_LENGTH_SOFT_LIMIT_CHARS, WritableBookPage::PAGE_LENGTH_HARD_LIMIT_BYTES, $cancel);
                $newBook->insertPage($packet->pageNumber, $text);
                $modifiedPages[] = $packet->pageNumber;
                break;
            case BookEditPacket::TYPE_DELETE_PAGE:
                if(!$newBook->pageExists($packet->pageNumber)){
                    return false;
                }
                $newBook->deletePage($packet->pageNumber);
                $modifiedPages[] = $packet->pageNumber;
                break;
            case BookEditPacket::TYPE_SWAP_PAGES:
                if($packet->pageNumber < 0 || $packet->secondaryPageNumber < 0){
                    throw new PacketHandlingException("Page numbers cannot be negative");
                }
                if(!$newBook->pageExists($packet->pageNumber) || !$newBook->pageExists($packet->secondaryPageNumber)){
                    //the client will create pages on its own without telling us until it tries to switch them
                    $newBook->addPage(max($packet->pageNumber, $packet->secondaryPageNumber));
                }
                $newBook->swapPages($packet->pageNumber, $packet->secondaryPageNumber);
                $modifiedPages = [$packet->pageNumber, $packet->secondaryPageNumber];
                break;
            case BookEditPacket::TYPE_SIGN_BOOK:
                $title = self::checkBookText($packet->title, "title", 16, Limits::INT16_MAX, $cancel);
                //this one doesn't have a limit in vanilla, so we have to improvise
                $author = self::checkBookText($packet->author, "author", 256, Limits::INT16_MAX, $cancel);
 
                $newBook = VanillaItems::WRITTEN_BOOK()
                    ->setPages($oldBook->getPages())
                    ->setAuthor($author)
                    ->setTitle($title)
                    ->setGeneration(WrittenBook::GENERATION_ORIGINAL);
                break;
            default:
                return false;
        }
 
        //for redundancy, in case of protocol changes, we don't want to pass these directly
        $action = match($packet->type){
            BookEditPacket::TYPE_REPLACE_PAGE => PlayerEditBookEvent::ACTION_REPLACE_PAGE,
            BookEditPacket::TYPE_ADD_PAGE => PlayerEditBookEvent::ACTION_ADD_PAGE,
            BookEditPacket::TYPE_DELETE_PAGE => PlayerEditBookEvent::ACTION_DELETE_PAGE,
            BookEditPacket::TYPE_SWAP_PAGES => PlayerEditBookEvent::ACTION_SWAP_PAGES,
            BookEditPacket::TYPE_SIGN_BOOK => PlayerEditBookEvent::ACTION_SIGN_BOOK,
            default => throw new AssumptionFailedError("We already filtered unknown types in the switch above")
        };
 
        /*
         * Plugins may have created books with more than 50 pages; we allow plugins to do this, but not players.
         * Don't allow the page count to grow past 50, but allow deleting, swapping or altering text of existing pages.
         */
        $oldPageCount = count($oldBook->getPages());
        $newPageCount = count($newBook->getPages());
        if(($newPageCount > $oldPageCount && $newPageCount > 50)){
            $this->session->getLogger()->debug("Cancelled book edit due to adding too many pages (new page count would be $newPageCount)");
            $cancel = true;
        }
 
        $event = new PlayerEditBookEvent($this->player, $oldBook, $newBook, $action, $modifiedPages);
        if($cancel){
            $event->cancel();
        }
 
        $event->call();
        if($event->isCancelled()){
            return true;
        }
 
        $this->player->getInventory()->setItem($packet->inventorySlot, $event->getNewBook());
 
        return true;
    }
 
    public function handleModalFormResponse(ModalFormResponsePacket $packet) : bool{
        if($packet->cancelReason !== null){
            //TODO: make APIs for this to allow plugins to use this information
            return $this->player->onFormSubmit($packet->formId, null);
        }elseif($packet->formData !== null){
            if(strlen($packet->formData) > self::MAX_FORM_RESPONSE_SIZE){
                throw new PacketHandlingException("Form response data too large, refusing to decode (received" . strlen($packet->formData) . " bytes, max " . self::MAX_FORM_RESPONSE_SIZE . " bytes)");
            }
            if(!$this->player->hasPendingForm($packet->formId)){
                $this->session->getLogger()->debug("Got unexpected response for form $packet->formId");
                return false;
            }
            try{
                $responseData = json_decode($packet->formData, true, self::MAX_FORM_RESPONSE_DEPTH, JSON_THROW_ON_ERROR);
            }catch(\JsonException $e){
                throw PacketHandlingException::wrap($e, "Failed to decode form response data");
            }
            return $this->player->onFormSubmit($packet->formId, $responseData);
        }else{
            throw new PacketHandlingException("Expected either formData or cancelReason to be set in ModalFormResponsePacket");
        }
    }
 
    public function handleLecternUpdate(LecternUpdatePacket $packet) : bool{
        $pos = $packet->blockPosition;
        $chunkX = $pos->getX() >> Chunk::COORD_BIT_SIZE;
        $chunkZ = $pos->getZ() >> Chunk::COORD_BIT_SIZE;
        $world = $this->player->getWorld();
        if(!$world->isChunkLoaded($chunkX, $chunkZ) || $world->isChunkLocked($chunkX, $chunkZ)){
            return false;
        }
 
        $lectern = $world->getBlockAt($pos->getX(), $pos->getY(), $pos->getZ());
        if($lectern instanceof Lectern && $this->player->canInteract($lectern->getPosition(), 15)){
            if(!$lectern->onPageTurn($packet->page)){
                $this->syncBlocksNearby($lectern->getPosition(), null);
            }
            return true;
        }
 
        return false;
    }
 
    public function handleEmote(EmotePacket $packet) : bool{
        $this->player->emote($packet->getEmoteId());
        return true;
    }
}