Skip to content

NetworkSession: add support for discarding repeated packets before th… #6715

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
wants to merge 2 commits into
base: minor-next
Choose a base branch
from
Open

NetworkSession: add support for discarding repeated packets before th… #6715

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
14b70c0
NetworkSession: add support for discarding repeated packets before th…
dktapps May 28, 2025
9946ea9
get rid of the old hack
dktapps May 28, 2025
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
57 changes: 57 additions & 0 deletions src/network/mcpe/NetworkSession.php
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -58,6 +58,7 @@
use pocketmine\network\mcpe\protocol\ClientboundCloseFormPacket;
use pocketmine\network\mcpe\protocol\ClientboundPacket;
use pocketmine\network\mcpe\protocol\DisconnectPacket;
use pocketmine\network\mcpe\protocol\InventoryTransactionPacket;
use pocketmine\network\mcpe\protocol\ModalFormRequestPacket;
use pocketmine\network\mcpe\protocol\MovePlayerPacket;
use pocketmine\network\mcpe\protocol\NetworkChunkPublisherUpdatePacket;
Expand Down Expand Up @@ -109,6 +110,7 @@
use pocketmine\Server;
use pocketmine\timings\Timings;
use pocketmine\utils\AssumptionFailedError;
use pocketmine\utils\Binary;
use pocketmine\utils\BinaryDataException;
use pocketmine\utils\BinaryStream;
use pocketmine\utils\ObjectSet;
Expand Down Expand Up @@ -194,6 +196,17 @@ class NetworkSession{
*/
private ObjectSet $disposeHooks;

/**
* @var string[]
* @phpstan-var array<int, string>
*/
private array $repeatedPacketFilters = [];
/**
* @var int[]
* @phpstan-var array<int, int>
*/
private array $repeatedPacketFilterStats = [];

public function __construct(
private Server $server,
private NetworkSessionManager $manager,
Expand Down Expand Up @@ -221,6 +234,8 @@ public function __construct(
$this->onSessionStartSuccess(...)
));

$this->addRepeatedPacketFilter(InventoryTransactionPacket::NETWORK_ID);

$this->manager->add($this);
$this->logger->info($this->server->getLanguage()->translate(KnownTranslationFactory::pocketmine_network_session_open()));
}
Expand Down Expand Up @@ -350,6 +365,44 @@ public function setHandler(?PacketHandler $handler) : void{
}
}

public function addRepeatedPacketFilter(int $packetId) : void{
$this->repeatedPacketFilters[$packetId] = "";
$this->repeatedPacketFilterStats[$packetId] = 0;
}

public function removeRepeatedPacketFilter(int $packetId) : void{
unset($this->repeatedPacketFilters[$packetId]);
unset($this->repeatedPacketFilterStats[$packetId]);
}

/**
* Returns the stats for repeated packet filters, indexed by packet ID.
* The value is the number of times a packet was dropped due to being repeated.
*
* @return int[]
* @phpstan-return array<int, int>
*/
public function getRepeatedPacketFilterStats() : array{
return $this->repeatedPacketFilterStats;
}

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]++;
return true;
}

$this->repeatedPacketFilters[$packetId] = $buffer;
}

return false;
}

/**
* @throws PacketHandlingException
*/
Expand Down Expand Up @@ -403,6 +456,10 @@ public function handleEncoded(string $payload) : void{
try{
$stream = new BinaryStream($decompressed);
foreach(PacketBatch::decodeRaw($stream) as $buffer){
if($this->checkRepeatedPacketFilter($buffer)){
continue;
}

$this->gamePacketLimiter->decrement();
$packet = $this->packetPool->getPacket($buffer);
if($packet === null){
Expand Down
22 changes: 1 addition & 21 deletions src/network/mcpe/handler/InGamePacketHandler.php
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -116,7 +116,6 @@
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;
Expand All @@ -128,9 +127,6 @@
class InGamePacketHandler extends PacketHandler{
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

protected float $lastRightClickTime = 0.0;
protected ?UseItemTransactionData $lastRightClickData = null;

protected ?Vector3 $lastPlayerAuthInputPosition = null;
protected ?float $lastPlayerAuthInputYaw = null;
protected ?float $lastPlayerAuthInputPitch = null;
Expand Down Expand Up @@ -471,27 +467,11 @@ private function handleUseItemTransaction(UseItemTransactionData $data) : bool{

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){
return true;
}
//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);
$this->player->interactBlock($vBlockPos, $data->getFace(), $data->getClickPosition());
//always sync this in case plugins caused a different result than the client expected
//we *could* try to enhance detection of plugin-altered behaviour, but this would require propagating
//more information up the stack. For now I think this is good enough.
Expand Down