ZeroDrop - Full Stack Command Execution App

A full-stack application that allows Android clients to send command line instructions and MySQL queries to a Node.js server for remote execution. Built with Express.js backend and Jetpack Compose frontend.

🏗️ Architecture

┌─────────────────┐    HTTP/HTTPS    ┌─────────────────┐
│   Android App   │ ────────────────► │   Node.js API   │
│ (Jetpack Compose) │                  │   (Express.js)  │
└─────────────────┘                  └─────────────────┘
                                               │
                                               ▼
                                      ┌─────────────────┐
                                      │   MySQL DB      │
                                      │                 │
                                      └─────────────────┘

🚀 Features

• Remote Command Execution: Execute system commands on the server from Android app
• MySQL Query Interface: Run database queries remotely with results returned to mobile client
• JWT Authentication: Secure login/register system with token-based authentication
• Modern UI: Clean Android interface built with Jetpack Compose
• Network Communication: RESTful API communication between client and server
• Port Forwarding Support: Easy development setup with VS Code port forwarding

📋 Prerequisites

Server Requirements

• Node.js (v14 or higher)
• MySQL Server
• VS Code (for development with port forwarding)

Android Requirements

• Android Studio
• Android SDK (API level 25+)
• Kotlin support

🛠️ Installation & Setup

1. Server Setup (Node.js/Express)

# Clone the repository
git clone https://github.com/Janadasroor/ZeroDrop.git
cd zerodrop/server

# Install dependencies
npm install

# Create environment variables file (Optional)
cp .env.example .env

# Make .env file in server folder (important) with your configuration
# DB_HOST=localhost
# DB_USER=your_mysql_user
# DB_PASS=your_mysql_password
# DB_NAME=zerodrop
# ACCESS_TOKEN_SECRET=make_strong_one
# REFRESH_TOKEN_SECRET=make_strong_one

# Start the server
npm start

2. Android App Setup

• Navigate to Android project
• Open client/ZeroDrop_Demo in Android Studio

3. VS Code Port Forwarding Configuration

1. Configure Port Forwarding:

   • It should be found near the terminal tab

2. Make Port Public:

   • In the Ports panel, right-click on your forwarded port
   • Select "Port Visibility" → "Public"
   • Copy the generated public URL (e.g., https://abc123-3000.preview.app.github.dev)

4. Configure Android Network Module

• Edit the file app/src/main/java/com/janad/zerodrop/data/api/NetworkModule.kt:

    // Replace with your VS Code port forwarding public URL
    private const val BASE_URL = "https://your-forwarded-url.preview.app.github.dev/"

📡 API Endpoints

Authentication

• POST /auth/register - User registration
• POST /auth/login - User login

Commands & Queries

• POST /run/command - Execute system command
• POST /run/query - Execute MySQL query

Example API Usage

// Login Request
POST /auth/login
{
  "email": "email",
  "password": "password123"
}

// Command Execution
POST /run/command
Headers: { "Authorization": "Bearer <token>" }
{
  "command": "ls -la"
}

// MySQL Query
POST /run/query
Headers: { "Authorization": "Bearer <token>" }
{
  "query": "SELECT * FROM admins LIMIT 5"
}

📱 Android App Structure

app/src/main/java/com/janad/zerodrop/
├── data/
│   ├── api/
│   │   ├── ApiService.kt
│   │   └── NetworkModule.kt          # ← Configure server URL here
└── MainActivity.kt

🔧 Development Workflow

For Server Development:

1. Make code changes
2. Server automatically reloads on code changes
3. Port forwarding automatically updates

For Android Development:

1. Update NetworkModule.kt with new forwarded URL if needed
2. Build and run Android app
3. Test API communication

Switching Between Environments:

// Development (VS Code Port Forwarding)
private const val BASE_URL = "https://abc123-3000.preview.app.github.dev/"

// Production
private const val BASE_URL = "https://your-production-server.com/"

// Local Development if you don't like to forward the port 
private const val BASE_URL = "http://10.0.2.2:3000/" // Android Emulator
// or
private const val BASE_URL = "http://192.168.1.100:3000/" // Physical Device
//This is your development machine ip on the same local network http://192.168.1.100

🔒 Security Considerations

• JWT access token refreshing every 5 minutes
• All API endpoints (except auth) require valid authentication
• Command execution is logged and monitored
• Database queries are parameterized to prevent SQL injection
• HTTPS required for production deployment

🐛 Troubleshooting

Common Issues:

1. Network Connection Failed

   • Verify VS Code port forwarding is active and public
   • Check NetworkModule.kt has correct URL
   • Ensure Android device/emulator has internet access

2. Authentication Failed

   • Check JWT token validity
   • Verify server is running and accessible
   • Confirm user credentials are correct

3. Command Execution Failed

   • Check server permissions for command execution
   • Verify MySQL connection settings
   • Review server logs for detailed error messages

📝 License

This project is licensed under the MIT License - see the LICENSE file for details.

👨‍💻 Author

Janada Sroor