EncapsulatedPacket.php

<?php
 
/*
 * This file is part of RakLib.
 * Copyright (C) 2014-2022 PocketMine Team <https://github.com/pmmp/RakLib>
 *
 * RakLib is not affiliated with Jenkins Software LLC nor RakNet.
 *
 * RakLib is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 */
 
declare(strict_types=1);
 
namespace raklib\protocol;
 
use pocketmine\utils\Binary;
use pocketmine\utils\BinaryDataException;
use pocketmine\utils\BinaryStream;
use function ceil;
use function chr;
use function strlen;
 
class EncapsulatedPacket{
    private const RELIABILITY_SHIFT = 5;
    private const RELIABILITY_FLAGS = 0b111 << self::RELIABILITY_SHIFT;
 
    private const SPLIT_FLAG = 0b00010000;
 
    public const SPLIT_INFO_LENGTH = 4 + 2 + 4; //split count (4) + split ID (2) + split index (4)
 
    public int $reliability;
    public ?int $messageIndex = null;
    public ?int $sequenceIndex = null;
    public ?int $orderIndex = null;
    public ?int $orderChannel = null;
    public ?SplitPacketInfo $splitInfo = null;
    public string $buffer = "";
    public ?int $identifierACK = null;
 
    public static function fromBinary(BinaryStream $stream) : EncapsulatedPacket{
        $packet = new EncapsulatedPacket();
 
        $flags = $stream->getByte();
        $packet->reliability = $reliability = ($flags & self::RELIABILITY_FLAGS) >> self::RELIABILITY_SHIFT;
        $hasSplit = ($flags & self::SPLIT_FLAG) !== 0;
 
        $length = (int) ceil($stream->getShort() / 8);
        if($length === 0){
            throw new BinaryDataException("Encapsulated payload length cannot be zero");
        }
 
        if(PacketReliability::isReliable($reliability)){
            $packet->messageIndex = $stream->getLTriad();
        }
 
        if(PacketReliability::isSequenced($reliability)){
            $packet->sequenceIndex = $stream->getLTriad();
        }
 
        if(PacketReliability::isSequencedOrOrdered($reliability)){
            $packet->orderIndex = $stream->getLTriad();
            $packet->orderChannel = $stream->getByte();
        }
 
        if($hasSplit){
            $splitCount = $stream->getInt();
            $splitID = $stream->getShort();
            $splitIndex = $stream->getInt();
            $packet->splitInfo = new SplitPacketInfo($splitID, $splitIndex, $splitCount);
        }
 
        $packet->buffer = $stream->get($length);
        return $packet;
    }
 
    public function toBinary() : string{
        return
            chr(($this->reliability << self::RELIABILITY_SHIFT) | ($this->splitInfo !== null ? self::SPLIT_FLAG : 0)) .
            Binary::writeShort(strlen($this->buffer) << 3) .
            (PacketReliability::isReliable($this->reliability) ? Binary::writeLTriad($this->messageIndex) : "") .
            (PacketReliability::isSequenced($this->reliability) ? Binary::writeLTriad($this->sequenceIndex) : "") .
            (PacketReliability::isSequencedOrOrdered($this->reliability) ? Binary::writeLTriad($this->orderIndex) . chr($this->orderChannel) : "") .
            ($this->splitInfo !== null ? Binary::writeInt($this->splitInfo->getTotalPartCount()) . Binary::writeShort($this->splitInfo->getId()) . Binary::writeInt($this->splitInfo->getPartIndex()) : "")
            . $this->buffer;
    }
 
    public function getHeaderLength() : int{
        return
            1 + //reliability
            2 + //length
            (PacketReliability::isReliable($this->reliability) ? 3 : 0) + //message index
            (PacketReliability::isSequenced($this->reliability) ? 3 : 0) + //sequence index
            (PacketReliability::isSequencedOrOrdered($this->reliability) ? 3 + 1 : 0) + //order index (3) + order channel (1)
            ($this->splitInfo !== null ? self::SPLIT_INFO_LENGTH : 0);
    }
 
    public function getTotalLength() : int{
        return $this->getHeaderLength() + strlen($this->buffer);
    }
 
    public function __toString() : string{
        return $this->toBinary();
    }
}