DataPacket: account for splitscreen header when decoding

src/pocketmine/network/mcpe/protocol/DataPacket.php

@@ -39,6 +39,12 @@ abstract class DataPacket extends NetworkBinaryStream{
 
 	public const NETWORK_ID = 0;
 
+	public const PID_MASK = 0x3ff; //10 bits
+
+	private const SUBCLIENT_ID_MASK = 0x03; //2 bits
+	private const SENDER_SUBCLIENT_ID_SHIFT = 10;
+	private const RECIPIENT_SUBCLIENT_ID_SHIFT = 12;
+
 	/** @var bool */
 	public $isEncoded = false;
 	/** @var CachedEncapsulatedPacket|null */
@@ -92,10 +98,13 @@ abstract class DataPacket extends NetworkBinaryStream{
 	 * @throws \UnexpectedValueException
 	 */
 	protected function decodeHeader(){
-		$pid = $this->getUnsignedVarInt();
+		$header = $this->getUnsignedVarInt();
+		$pid = $header & self::PID_MASK;
 		if($pid !== static::NETWORK_ID){
 			throw new \UnexpectedValueException("Expected " . static::NETWORK_ID . " for packet ID, got $pid");
 		}
+		$this->senderSubId = ($header >> self::SENDER_SUBCLIENT_ID_SHIFT) & self::SUBCLIENT_ID_MASK;
+		$this->recipientSubId = ($header >> self::RECIPIENT_SUBCLIENT_ID_SHIFT) & self::SUBCLIENT_ID_MASK;
 	}
 
 	/**
@@ -123,7 +132,11 @@ abstract class DataPacket extends NetworkBinaryStream{
 	 * @return void
 	 */
 	protected function encodeHeader(){
-		$this->putUnsignedVarInt(static::NETWORK_ID);
+		$this->putUnsignedVarInt(
+			static::NETWORK_ID |
+			($this->senderSubId << self::SENDER_SUBCLIENT_ID_SHIFT) |
+			($this->recipientSubId << self::RECIPIENT_SUBCLIENT_ID_SHIFT)
+		);
 	}
 
 	/**

src/pocketmine/network/mcpe/protocol/PacketPool.php

@@ -196,7 +196,7 @@ class PacketPool{
 	 */
 	public static function getPacket(string $buffer) : DataPacket{
 		$offset = 0;
-		$pk = static::getPacketById(Binary::readUnsignedVarInt($buffer, $offset));
+		$pk = static::getPacketById(Binary::readUnsignedVarInt($buffer, $offset) & DataPacket::PID_MASK);
 		$pk->setBuffer($buffer, $offset);
 
 		return $pk;

tests/phpunit/network/mcpe/protocol/DataPacketTest.php

@@ -0,0 +1,42 @@
+<?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\protocol;
+
+use PHPUnit\Framework\TestCase;
+
+class DataPacketTest extends TestCase{
+
+	public function testHeaderFidelity() : void{
+		$pk = new TestPacket();
+		$pk->senderSubId = 3;
+		$pk->recipientSubId = 2;
+		$pk->encode();
+
+		$pk2 = new TestPacket();
+		$pk2->setBuffer($pk->getBuffer());
+		$pk2->decode();
+		self::assertSame($pk2->senderSubId, 3);
+		self::assertSame($pk2->recipientSubId, 2);
+	}
+}

tests/phpunit/network/mcpe/protocol/TestPacket.php

@@ -0,0 +1,34 @@
+<?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\protocol;
+
+use pocketmine\network\mcpe\NetworkSession;
+
+class TestPacket extends DataPacket{
+	public const NETWORK_ID = 1023;
+
+	public function handle(NetworkSession $handler) : bool{
+		return false;
+	}
+}