Phantom - GTA V Multiplayer Framework (Educational Purpose Only)

Disclaimer:
This project is for educational purposes only.
It is not intended for cheating, piracy, or violating the terms of service of any software.
The authors are not responsible for any misuse of this code.

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Overview

Phantom is an experimental framework that demonstrates the technical foundations required to implement a custom multiplayer system in Grand Theft Auto V.

Inspired by popular multiplayer mods (like FiveM, RageMP, and AltV), this repository explores:

• DLL injection techniques
• Game memory manipulation and pattern scanning
• Hooking native GTA V functions (VMT hooks, Microsoft Detours)
• D3D11 overlay rendering (Ultralight HTML/CSS/JS)
• WebSocket networking with FlatBuffers serialization
• Async multiplayer server architecture

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Architecture

The project consists of a C++26 injection toolchain and an async Rust server:

Component	Language	Type	Purpose
Phantom.Hook	C++26	Static lib	Core hooking engine: memory abstractions, pattern scanning, VMT/Detours hooks, D3D11 hook, input hook, fiber manager, native invoker
Phantom.Client	C++26	DLL (client.dll)	Injected into GTA V: game state, entity management, script thread, Ultralight overlay, WebSocket client
Phantom.Launcher	C++26	Executable	DLL injector: finds/launches GTA V, injects client.dll
Phantom.Shared	C++26	Static lib	Shared constants, entity types, FlatBuffers schema
Server	Rust	Binary	Async Tokio WebSocket server with player sessions and entity sync

Dependency Graph

Phantom.Launcher --> Phantom.Shared
Phantom.Client  --> Phantom.Hook --> Phantom.Shared
Phantom.Client  --> Phantom.Shared

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Requirements

• Windows 10+ (x64)
• Visual Studio 2022 (C++ Desktop Development workload, v143 toolset)
• Rust toolchain (for the server)
• Third-party dependencies (see below)

Third-Party Dependencies

Dependency	Purpose
Microsoft Detours	Inline function hooking
Ultralight	HTML/CSS/JS overlay rendering
spdlog	Logging
Google Test	C++ testing framework
FlatBuffers	Cross-language serialization
IXWebSocket	WebSocket client (C++)

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Build

C++ (Client, Hook, Launcher)

1. Clone the repository
2. Place third-party dependencies in the appropriate include/lib paths (see Directory.Build.props and each .vcxproj for expected paths)
3. Open Phantom.sln in Visual Studio 2022
4. Build in Debug|x64 or Release|x64

Rust Server

cd server
cargo build --release

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Usage

1. Start the server:

   cd server
   cargo run --release

2. Launch GTA V and inject:

   # Launch GTA V and inject automatically
   Phantom.Launcher.exe --launch
   
   # Or inject into an already running GTA V
   Phantom.Launcher.exe --attach

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Project Structure

Phantom.sln
├── Phantom.Hook/              # Static lib — hooking engine
│   ├── include/hook/          # Public headers
│   └── src/                   # Implementation
├── Phantom.Client/            # DLL — injected into GTA V
│   ├── include/client/        # Public headers
│   ├── src/                   # Implementation
│   └── ui/                    # HTML/CSS/JS overlay assets
├── Phantom.Launcher/          # Executable — DLL injector
│   ├── include/launcher/
│   └── src/
├── Phantom.Shared/            # Static lib — shared types
│   ├── include/shared/
│   └── src/
├── Phantom.Hook.Tests/        # Google Test suite
├── Phantom.Client.Tests/
├── Phantom.Launcher.Tests/
├── server/                    # Rust async server
│   └── src/
├── Directory.Build.props      # Shared C++26 build settings
├── .clang-format              # Code formatting rules
├── .clang-tidy                # Static analysis config
└── CLAUDE.md                  # Detailed project documentation

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Key Technical Details

• C++26 with /std:c++latest — uses std::expected, concepts, structured bindings
• No exceptions — all error handling via std::expected<T, Error>
• RAII everywhere — ScopedHandle, VMTHook, DetoursHook auto-cleanup
• Overlay is swappable — IOverlay interface allows replacing Ultralight with CEF
• FlatBuffers schema at Phantom.Shared/include/shared/messages.fbs is the protocol source of truth
• Crossmap (hook/crossmap.h) translates GTA V native hashes between game versions — currently a stub

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License

This project is provided as-is for educational purposes. See individual third-party dependency licenses for their terms.