mdnscpp

mdnscpp is a lightweight C++ library for browsing mDNS (Multicast DNS) services, also known as DNS-SD (DNS-based Service Discovery). It provides a unified API to discover services across platforms using one of the following backends:

• Bonjour / dns_sd (macOS, iOS)
• Avahi (Linux)
• Win32 API (Windows)

The main goal of this library is to abstract away platform-specific implementations, enabling developers to write portable mDNS client code.

✨ Features

• Cross-platform support
• Automatic backend selection
• Asynchronous event-driven design
• Sorted service result listing
• Simple and consistent C++ API

🔄 Event Loop Abstraction

mdnscpp internally abstracts the event loop to allow flexibility and seamless integration with different runtime environments. This makes the library adaptable for a variety of use cases, from simple command-line tools to full-featured GUI or server applications.

Built-in Event Loop Implementations

• Default Poll-Based Loop
  A minimal, platform-independent implementation using poll()—intended primarily for testing and standalone use.

• libuv Integration
  Full support for libuv, enabling integration with applications already using the libuv event loop (e.g. Node.js backends or other asynchronous systems).

Extensibility

The event loop system is designed with extensibility in mind. Future or user-contributed integrations could include support for other frameworks such as Boost.Asio.

This architecture ensures that mdnscpp can be embedded cleanly into existing systems without imposing its own threading or timing model.

🔧 Requirements

• C++17 or later
• Platform-specific mDNS backend:
  • dns_sd.h (Bonjour) on macOS/iOS
  • avahi-client and avahi-common on Linux
  • Native DNS-SD support on Windows

---

🛠️ Building

You can build mdnscpp using CMake:

cmake -Bbuild
cmake --build build -j4

🚀 Example Usage

#include <iostream>

#include <mdnscpp/DefaultLoop.h>
#include <mdnscpp/Platform.h>
#include <mdnscpp/utils.h>

int main(int argc, const char **argv)
{
    mdnscpp::DefaultLoop loop;

    auto platform = mdnscpp::createPlatform(loop);

    auto browser = platform->createBrowser("_http_", "_tcp", [](auto browser) {
        auto results = mdnscpp::getSortedList(browser->getResults());
        std::cout << "Results (" << results.size() << "): " << std::endl;
        for (const auto &result : results)
        {
            std::cout << result.describe() << std::endl;
        }
    });

    loop.run();
    return 0;
}

This example sets up a service browser for services advertising _oca._tcp, prints out sorted results, and runs the event loop until interrupted.

📦 API Overview

• mdnscpp::DefaultLoop - Event loop abstraction
• mdnscpp::createPlatform() - Initializes platform-specific backend
• Platform::createBrowser() - Starts browsing for a given service type
• Browser::getResults() - Access discovered services
• mdnscpp::getSortedList() - Helper to get sorted service list
• ServiceResult::describe() - Returns a human-readable description of the result

🙋‍♂️ Contributions

Contributions, suggestions, and bug reports are welcome! Please open an issue or submit a pull request.

📫 Contact

For questions or feedback, feel free to reach out or open an issue on the repository.

📜 License

This library is released under the terms of the MIT License.

Copyright (c) 2024-2025 Arne Gödeke