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NetworkSession: extract rate limiting functionality into its own unit, and apply a separate rate limit to game packets

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Dylan K. Taylor
2023-04-10 13:53:15 +01:00
parent 7b55c984bf
commit 24374297e7
2 changed files with 91 additions and 37 deletions
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80
src/network/mcpe/PacketRateLimiter.php Normal file
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<?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;
use pocketmine\network\PacketHandlingException;
use function intdiv;
use function min;
final class PacketRateLimiter{
/**
* At most this many more packets can be received. If this reaches zero, any additional packets received will cause
* the player to be kicked from the server.
* This number is increased every tick up to a maximum limit, and decreased by one every time a packet is received.
*/
private int $budget;
private int $lastUpdateTimeNs;
private int $maxBudget;
public function __construct(
private string $name,
private int $averagePerTick,
int $maxBufferTicks,
private int $updateFrequencyNs = 50_000_000,
){
$this->maxBudget = $this->averagePerTick * $maxBufferTicks;
$this->budget = $this->maxBudget;
$this->lastUpdateTimeNs = hrtime(true);
}
/**
* @throws PacketHandlingException if the rate limit has been exceeded
*/
public function decrement(int $amount = 1) : void{
if($this->budget <= 0){
$this->update();
if($this->budget <= 0){
throw new PacketHandlingException("Exceeded rate limit for \"$this->name\"");
}
}
$this->budget -= $amount;
}
public function update() : void{
$nowNs = hrtime(true);
$timeSinceLastUpdateNs = $nowNs - $this->lastUpdateTimeNs;
if($timeSinceLastUpdateNs > $this->updateFrequencyNs){
$ticksSinceLastUpdate = intdiv($timeSinceLastUpdateNs, $this->updateFrequencyNs);
/*
* If the server takes an abnormally long time to process a tick, add the budget for time difference to
* compensate. This extra budget may be very large, but it will disappear the next time a normal update
* occurs. This ensures that backlogs during a large lag spike don't cause everyone to get kicked.
* As long as all the backlogged packets are processed before the next tick, everything should be OK for
* clients behaving normally.
*/
$this->budget = min($this->budget, $this->maxBudget) + ($this->averagePerTick * 2 * $ticksSinceLastUpdate);
$this->lastUpdateTimeNs = $nowNs;
}
}
}