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README.md

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+# DNS Service
+
+[![License: MIT](https://img.shields.io/badge/License-MIT-yellow.svg)](https://opensource.org/licenses/MIT)
+
+A lightweight DNS management service written in C with a web-based interface for configuring DNS settings and managing dnsmasq configuration.
+
+## Features
+
+- **Web Interface**: Modern responsive web UI for DNS configuration
+- **DNS Settings Management**: Configure upstream DNS servers, local domains, and cache settings
+- **DHCP Configuration**: Enable/disable DHCP with range configuration
+- **File Management**: Direct editing of configuration files
+- **SSL/TLS Support**: Optional HTTPS with certificate configuration
+- **JSON Configuration**: Easy-to-manage JSON-based configuration
+- **Cross-platform**: Supports multiple build systems (Make, CMake, Meson)
+
+## Architecture
+
+The service consists of:
+- **HTTP/HTTPS Server**: Built on Mongoose web server
+- **REST API**: JSON-based API for configuration management
+- **Web Interface**: Bootstrap-based responsive UI
+- **Configuration Parser**: Custom dnsmasq config parser
+- **File Operations**: Safe file reading/writing utilities
+
+## API Endpoints
+
+| Method | Endpoint | Description |
+|--------|----------|-------------|
+| GET | `/api/settings` | Get current DNS settings |
+| POST | `/api/settings` | Update DNS settings |
+| GET | `/api/settings/file` | Get raw configuration file |
+| POST | `/api/settings/file` | Update configuration file |
+| GET | `/#` | Serve web interface |
+
+## Requirements
+
+### Build Dependencies
+- GCC compiler with C23 support
+- OpenSSL development libraries
+- pthread library
+
+### System Dependencies
+- dnsmasq (for DNS service functionality)
+- SSL certificates (for HTTPS support)
+
+## Installation
+
+### Using Make
+```bash
+make
+```
+
+### Using CMake
+```bash
+mkdir build && cd build
+cmake ..
+make
+```
+
+### Using Meson
+```bash
+meson setup builddir
+meson compile -C builddir
+```
+
+## Configuration
+
+Edit `config.json` to configure the service:
+
+```json
+{
+    "address": "0.0.0.0:8321",
+    "tls_address": "0.0.0.0:8322",
+    "web": "./web",
+    "tls_enabled": true,
+    "tls_cert": "/path/to/certificate.crt",
+    "tls_key": "/path/to/private.key",
+    "system_initialization": "rc",
+    "dnsmasq_config": "/etc/dnsmasq.conf"
+}
+```
+
+### Configuration Parameters
+
+- `address`: HTTP server bind address and port
+- `tls_address`: HTTPS server bind address and port
+- `web`: Path to web interface files
+- `tls_enabled`: Enable/disable HTTPS support
+- `tls_cert`: Path to SSL certificate file
+- `tls_key`: Path to SSL private key file
+- `system_initialization`: System initialization type
+- `dnsmasq_config`: Path to dnsmasq configuration file
+
+## Usage
+
+### Starting the Service
+```bash
+./dns_service
+```
+
+The service will start HTTP server on the configured address (default: `0.0.0.0:8321`) and optionally HTTPS server if TLS is enabled.
+
+### Web Interface
+
+Navigate to `http://localhost:8321` (or your configured address) to access the web interface where you can:
+
+- Configure upstream DNS servers
+- Manage local domain mappings
+- Enable/disable DHCP with range settings
+- Adjust DNS cache size
+- Edit configuration files directly
+
+### API Usage
+
+#### Get Current Settings
+```bash
+curl -X GET http://localhost:8321/api/settings
+```
+
+#### Update Settings
+```bash
+curl -X POST http://localhost:8321/api/settings \
+  -H "Content-Type: application/json" \
+  -d '{"cache_size": 1000, "resolv": ["8.8.8.8", "8.8.4.4"]}'
+```
+
+## Development
+
+### Project Structure
+```
+dns_service_c/
+├── src/
+│   ├── lib/           # Third-party libraries
+│   │   ├── mongoose.c # HTTP server
+│   │   ├── cJSON.c    # JSON parser
+│   │   └── ...
+│   ├── main.c         # Application entry point
+│   ├── config.c       # Configuration management
+│   ├── settings.c     # DNS settings handlers
+│   └── ...
+├── web/               # Web interface files
+│   ├── index.html
+│   ├── css/
+│   └── js/
+├── config.json        # Service configuration
+└── README.md
+```
+
+### Building for Development
+```bash
+# With debug symbols
+make CFLAGS="-Wall -g -std=gnu2x -DDEBUG"
+
+# Clean build
+make clean && make
+```
+
+### Code Style
+The project uses `.clang-format` for consistent code formatting:
+```bash
+clang-format -i src/*.c src/*.h
+```
+
+## Security Considerations
+
+- The service runs with system privileges to modify DNS configuration
+- HTTPS is strongly recommended for production deployments
+- Ensure proper file permissions on certificate files
+- Consider firewall rules to restrict access to management interface
+
+## Troubleshooting
+
+### Common Issues
+
+1. **Permission denied when accessing dnsmasq config**
+   - Ensure the service has read/write permissions to the dnsmasq configuration file
+   - Run with appropriate privileges or adjust file permissions
+
+2. **SSL/TLS certificate errors**
+   - Verify certificate and key file paths in `config.json`
+   - Ensure certificate files have correct permissions
+   - Check certificate validity and format
+
+3. **Port binding errors**
+   - Verify ports are not already in use
+   - Check firewall settings
+   - Ensure proper privileges for binding to privileged ports
+
+### Logging
+The service uses Mongoose's built-in logging. Set log level in code or use debug build for verbose output.
+
+## Contributing
+
+1. Fork the repository
+2. Create a feature branch
+3. Make your changes following the existing code style
+4. Test your changes thoroughly
+5. Submit a pull request
+
+## License
+
+This project is licensed under the MIT License - see the [LICENSE](LICENSE) file for details.
+
+### Third-party Libraries
+
+This project includes the following third-party libraries:
+
+- **Mongoose**: HTTP/WebSocket server library
+- **cJSON**: JSON parser library
+
+Please refer to their respective licenses for usage terms.
+
+## Support
+
+For issues and questions, please check the project's issue tracker or documentation.