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// SPDX-License-Identifier: GPL-3.0-only
// SPDX-FileCopyrightText: 2026 Project Tick
// SPDX-FileContributor: Project Tick Team
/*
* ProjT Launcher - Minecraft Launcher
* Copyright (C) 2026 Project Tick
*
* This program 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, version 3.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, write to the Free Software Foundation,
* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
#include <qtconcurrentrun.h>
#include <QJsonDocument>
#include <QJsonObject>
#include <QObject>
#include <QTcpSocket>
#include <Exception.h>
#include "Json.h"
#include "McClient.h"
// 7 first bits
#define SEGMENT_BITS 0x7F
// last bit
#define CONTINUE_BIT 0x80
McClient::McClient(QObject* parent, QString domain, QString ip, short port)
: QObject(parent),
m_domain(domain),
m_ip(ip),
m_port(port)
{}
void McClient::getStatusData()
{
qDebug() << "Connecting to socket..";
connect(&m_socket,
&QTcpSocket::connected,
this,
[this]()
{
qDebug() << "Connected to socket successfully";
sendRequest();
connect(&m_socket, &QTcpSocket::readyRead, this, &McClient::readRawResponse);
});
connect(&m_socket,
&QTcpSocket::errorOccurred,
this,
[this]() { emitFail("Socket disconnected: " + m_socket.errorString()); });
m_socket.connectToHost(m_ip, m_port);
}
void McClient::sendRequest()
{
QByteArray data;
writeVarInt(data, 0x00); // packet ID
writeVarInt(data, 763); // hardcoded protocol version (763 = 1.20.1)
writeVarInt(data, m_domain.size()); // server address length
writeString(data, m_domain.toStdString()); // server address
writeFixedInt(data, m_port, 2); // server port
writeVarInt(data, 0x01); // next state
writePacketToSocket(data); // send handshake packet
writeVarInt(data, 0x00); // packet ID
writePacketToSocket(data); // send status packet
}
void McClient::readRawResponse()
{
if (m_responseReadState == 2)
{
return;
}
m_resp.append(m_socket.readAll());
if (m_responseReadState == 0 && m_resp.size() >= 5)
{
m_wantedRespLength = readVarInt(m_resp);
m_responseReadState = 1;
}
if (m_responseReadState == 1 && m_resp.size() >= m_wantedRespLength)
{
if (m_resp.size() > m_wantedRespLength)
{
qDebug() << "Warning: Packet length doesn't match actual packet size (" << m_wantedRespLength
<< " expected vs " << m_resp.size() << " received)";
}
parseResponse();
m_responseReadState = 2;
}
}
void McClient::parseResponse()
{
qDebug() << "Received response successfully";
int packetID = readVarInt(m_resp);
if (packetID != 0x00)
{
throw Exception(QString("Packet ID doesn't match expected value (0x00 vs 0x%1)").arg(packetID, 0, 16));
}
Q_UNUSED(readVarInt(m_resp)); // json length
// 'resp' should now be the JSON string
QJsonDocument doc = QJsonDocument::fromJson(m_resp);
emitSucceed(doc.object());
}
// From https://wiki.vg/Protocol#VarInt_and_VarLong
void McClient::writeVarInt(QByteArray& data, int value)
{
while ((value & ~SEGMENT_BITS))
{ // check if the value is too big to fit in 7 bits
// Write 7 bits
data.append((value & SEGMENT_BITS) | CONTINUE_BIT);
// Erase theses 7 bits from the value to write
// Note: >>> means that the sign bit is shifted with the rest of the number rather than being left alone
value >>= 7;
}
data.append(value);
}
// From https://wiki.vg/Protocol#VarInt_and_VarLong
int McClient::readVarInt(QByteArray& data)
{
int value = 0;
int position = 0;
char currentByte;
while (position < 32)
{
currentByte = readByte(data);
value |= (currentByte & SEGMENT_BITS) << position;
if ((currentByte & CONTINUE_BIT) == 0)
break;
position += 7;
}
if (position >= 32)
throw Exception("VarInt is too big");
return value;
}
char McClient::readByte(QByteArray& data)
{
if (data.isEmpty())
{
throw Exception("No more bytes to read");
}
char byte = data.at(0);
data.remove(0, 1);
return byte;
}
// write number with specified size in big endian format
void McClient::writeFixedInt(QByteArray& data, int value, int size)
{
for (int i = size - 1; i >= 0; i--)
{
data.append((value >> (i * 8)) & 0xFF);
}
}
void McClient::writeString(QByteArray& data, const std::string& value)
{
data.append(value.c_str());
}
void McClient::writePacketToSocket(QByteArray& data)
{
// we prefix the packet with its length
QByteArray dataWithSize;
writeVarInt(dataWithSize, data.size());
dataWithSize.append(data);
// write it to the socket
m_socket.write(dataWithSize);
m_socket.flush();
data.clear();
}
void McClient::emitFail(QString error)
{
qDebug() << "Minecraft server ping for status error:" << error;
emit failed(error);
emit finished();
}
void McClient::emitSucceed(QJsonObject data)
{
emit succeeded(data);
emit finished();
}
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