# Unity Anti Mod Loader Framework

A lightweight, zero-dependency C# security utility for Unity games designed to detect unauthorized mod loader frameworks (**MelonLoader** and **BepInEx**) using fast filesystem verification (`File.Exists` & `Directory.Exists`) and DLL proxy heuristic checks.

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## Features

- **MelonLoader Detection**:
  - Detects core directory structures (`MelonLoader/`, `MelonLoader/Dependencies/`, `Mods/`, `UserLibs/`).
  - Scans for bootstrap DLLs and loader hooks (`version.dll`, `winmm.dll`, `MelonLoader.dll`, `Bootstrap.dll`).
- **BepInEx Detection**:
  - Detects core directory structures (`BepInEx/`, `BepInEx/core/`, `BepInEx/plugins/`, `BepInEx/patchers/`).
  - Scans for Unity Doorstop files and injection proxies (`winhttp.dll`, `doorstop_config.ini`, `BepInEx.Core.dll`, `0Harmony.dll`).
- **Zero Overhead**: Synchronous filesystem checks executed at startup before scene load with 0 runtime GC pressure.
- **Cross-Platform Compatibility**: Fully compatible with Unity Standalone Windows (x86 / x64), macOS, and Linux builds.

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## Detection Mechanism

Mod loaders for Unity games rely on DLL proxying / hijacking to intercept the engine runtime before `UnityPlayer.dll` initializes:
1. **BepInEx**: Uses Unity Doorstop (`winhttp.dll` or `doorstop_config.ini`) and places assemblies inside the `BepInEx/` directory.
2. **MelonLoader**: Uses native proxy DLLs (`version.dll` or `winmm.dll`) and initializes modules inside `MelonLoader/Dependencies/`.

`Unity-AntiModLoader` inspects the active game execution root using `Application.dataPath` parent resolution and queries standard path signatures.

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## Quick Start

### Basic Check

```csharp
using UnityEngine;
using UnityAntiModLoader;

public class SecurityBootstrapper : MonoBehaviour
{
    private void Awake()
    {
        if (AntiModLoader.IsAnyModLoaderPresent())
        {
            Debug.LogError("[Security] Mod loader detected! Terminating game.");
            Application.Quit();
        }
    }
}
```

### Detailed Detection Results

```csharp
using System.Collections.Generic;
using UnityEngine;
using UnityAntiModLoader;
using UnityAntiModLoader.Models;

public class GameSecurityManager : MonoBehaviour
{
    private void Start()
    {
        List<ModDetectionResult> results = AntiModLoader.RunFullCheck();

        foreach (ModDetectionResult result in results)
        {
            Debug.LogWarning($"Detected Framework: {result.FrameworkName}");
            Debug.LogWarning($"Severity Level: {result.Severity}");
            
            foreach (string artifact in result.DetectedArtifacts)
            {
                Debug.LogWarning($"  -> Artifact: {artifact}");
            }
        }
    }
}
```

---

## Project Structure

```
src/
├── Detectors/
│   ├── BepInExDetector.cs      # BepInEx files, doorstop configs & proxy DLL checks
│   └── MelonLoaderDetector.cs  # MelonLoader directory & version.dll checks
├── Example/
│   └── ModDetectionListener.cs # Example MonoBehaviour integration & auto-quit
├── Models/
│   └── ModDetectionResult.cs   # Detection result data container & severity enum
└── AntiModLoader.cs            # Primary entry point & game root resolver
```

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## License

Released under the [MIT License](LICENSE).