The Metin2 Server

The Old Metin2 Project aims at improving and maintaining the 2014 Metin2 game files up to modern standards. The goal is to archive the game as it was in order to preserve it for the future and enable nostalgic players to have a good time.

For-profit usage of this material is certainly illegal without the proper licensing agreements and is hereby discouraged (not legal advice). Even so, the nature of this project is HIGHLY EXPERIMENTAL - bugs are to be expected for now.

1. Building and usage

A. Use Docker to instantly bring up a server (recommended)

We aim to provide Docker images which just work for your convenience. A Docker Compose project is maintained in the Deployment project. Please head over there for further instructions.

B. Build the binaries yourself (for advanced users)

Sadly, we're unable to provide hand-holding services. You should have some C++ development experience going forward with this route.

A Linux environment is strongly recommended, preferably of the Ubuntu/Debian variety. This project is also compatible with WSL, even though WSL can be buggy at times. FreeBSD/Windows compatibility is untested and unsupported for the time being - there are other projects out there if that's what you want.

On your Linux box, install the dependencies for vcpkg and the other libraries we're going to install.

apt-get update
apt-get install -y git cmake build-essential tar curl zip unzip pkg-config autoconf python3 libncurses5-dev

Also install DevIL (1.7.8) and the BSD compatibility library:

apt-get install -y libdevil-dev libbsd-dev

Install vcpkg according to the lastest instructions.

Build and install the required libraries:

vcpkg install boost-system cryptopp effolkronium-random libmysql libevent lzo fmt spdlog argon2

Then, it's time to build your binaries. Your commands should look along the lines of:

mkdir build/
cd build && cmake -DCMAKE_TOOLCHAIN_FILE=/path/to/vcpkg/scripts/buildsystems/vcpkg.cmake ..
make -j $(nproc)

If everything goes right, you should now have compiled binaries you should just be able to use as a drop-in replacement for your BSD binaries in your favourite serverfiles.

2. Development

The preferred IDE in order to develop and debug the server is CLion, baked by the fine Czech folks at JetBrains. Educational licenses are available if you're elligible.

Make sure you install all the dependencies mentioned in the "Build the binaries yourself" section.
Inside a WSL environment, a remote SSH one or directly on a Linux machine, just clone this repository and open it with CLion.
Set up "Run/Debug Configurations" of the "CMake Application" type for the db, auth, and game services, using the "db" target for the former and the "game" target for the latter two. Make sure each service has its own working directory with all the required configuration and game files.
Optionally, add a "Compound" configuration containing these three configurations in order to start them at once.
Of course, you'll need a MySQL 5.x database, Valgrind and any other development goodies you wish. Also, a lot of time.

3. Improvements

Major improvements

The binaries run on 64-bit Linux with the network stack being partially rewritten in Libevent.
CMake build system mainly based on vcpkg. Docker-friendly architectural approach.
HackShield and other proprietary binaries were successfully yeeted, the project only has open-source dependencies.
Included gamefiles from TMP4's server files (2023.08.05 version).

Minor improvements

Removed unused functionalities (time bombs, activation servers, other Korean stuff)
Switched to the effolkronium/random PRNG instead of the standard C functions.
Refactored macros to modern C++ functions.
Network settings are manually configurable through the PUBLIC_IP, PUBLIC_BIND_IP, INTERNAL_IP, INTERNAL_BIND_IP settings in the CONFIG file. (Might need further work)
Refactored logging to use spdlog for more consistent function calls.
Refactored login code to use Argon2ID.

4. Bugfixes

WARNING: This project is based on the "kraizy" leak. That was over 10 years ago. A lot of exploits and bugs were discovered since then. Most of these public bugs are UNPATCHED. This is a very serious security risk and one of the reasons this project is still experimental.

Gameplay

Fixed invisibility bug on login/respawn/teleport etc.
Fixed player level not updating (thread)

Exploits

See the warning above :(

Architectural

Fixed various bugs caused by the migration of the codebase to 64-bit (some C/C++ data types have different lengths based on the CPU architecture)
Fixed buffer overruns and hardcoded limits in the MAP_ALLOW parsing routines.
Fixed quest server timers cancellation bug which could cause a server crash - (thread).
Fixed buffer overruns and integer overflows in SQL queries.

5. Further plans

Migrate conf.txt and CONFIG to a modern dotenv-like format, which would enable pretty nice Docker images.
Add a health check to the Docker image.
Use the fmt library for safe and modern string formatting.
Handle kernel signals (SIGTERM, SIGHUP etc.) for gracefully shutting down the game server.
Improve memory safety.
Use fixed width integer types instead of Microsoft-style typedefs.
Convert C-style strings to C++ std::string.
Perform static and runtime analysis.
Find and implement other fitting improvements from projects such as Vanilla's core, TMP's serverfiles.
Find time to take care of this project.

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