GNU libmicrohttpd

GNU libmicrohttpd is an open source library designed to facilitate the integration of high-performance HTTP server functionality into diverse software applications. This makes it easy to provide and deliver web services from within an existing software application, enabling communication between all kinds of devices for all kinds of purposes. Originally developed over 17 years ago, libmicrohttpd offers developers a reliable and efficient solution for embedding lightweight web server capabilities. As a critical component in numerous projects, ranging from embedded systems to content delivery networks, libmicrohttpd’s versatility and robust feature set have cemented its status as a popular choice among developers.

The libmicrohttpd project is undergoing significant maintenance and enhancement efforts to ensure its continued relevance and reliability. These efforts include the development of a new Application Programming Interface (API), restructuring of the codebase for improved modularity, and expansion of the automated testing suite to enhance security and stability. Investing in these improvements recognizes libmicrohttpd’s position as a cornerstone tool for building HTTP servers, and contributing to the long-term sustainability and security of the FOSS ecosystem.

GNU libmicrohttpd provides a robust and efficient framework for various applications to also delivering HTTP (web) pages. The HTTP protocol is a cornerstone of online communication, facilitating data exchange between clients and servers. libmicrohttpd’s lightweight nature and high-performance capabilities make it an invaluable tool for developers seeking to incorporate web server functionality into their projects, regardless of scale or complexity. Whether utilized in embedded systems, content delivery networks, or other software applications, libmicrohttpd plays a pivotal role in enabling reliable and efficient communication over the web.

Thousands of projects and businesses use libmicrohttpd, including NASA (Earth Observation satellite data distribution), Sony televisions, security cameras, medical testing laboratories, and numerous Free Software projects. To name just a few: GNUnet, Kodi, GNU Taler, Retroshare, P4P Portal, Gnome Music Player Client CallHome, Open Lighting Architecture, and systemd (journal gatewayd).

The Sovereign Tech Fund is commissioning improvements to GNU libmicrohttpd that increase the library’s security, resilience, and ease of use, for many critical applications, while also making it more compatible with the latest standards and clients which will contribute to its long term sustainability. The improvements include the development of a new Application Programming Interface (API), restructuring the codebase for modularity and ease of maintenance, and expand the automated testing suite, to provide more comprehensive and deeper testing.

1. API Enhancement and Refinement:
   • Develop and document the microhttpd (MHD) v2 API to encompass all features of MHD v1 while enhancing usability, safety, and adaptability.
   • Divide the API into six functional groups, including core HTTP request processing, HTTP POST body parsing, WebSocket support, TLS support, HTTP client authentication, and introspection.
2. Core Functionality Strengthening:
   • Implement and test core HTTP request processing functionality, including support for different event loop styles and HTTP response generation.
   • Develop a convenience API for incremental parsing of HTTP POST data to improve safety and ease of use.
3. Enhancing Protocol Support:
   • Implement WebSocket support to accommodate modern web applications.
   • Integrate and test TLS support with options for underlying libraries and runtime flexibility.
   • Implement HTTP authentication support for secure application authentication mechanisms.
4. API Documentation and Migration:
   • Document the complete v2 API in the microhttpd handbook and update tutorials with examples.
   • Develop a migration guide for transitioning existing code to the new API.
   • Evaluate the migration process by transforming an existing service to utilize the new API.
5. Performance Evaluation and Validation:
   • Conduct a detailed performance evaluation comparing microhttpd v1 to v2 and address any significant regressions.
   • Validate code compilation across various platforms and architectures.
   • Perform extensive code analysis and expand the testing suite with automated fuzzing.
6. Protocol Evolution and Integration:
   • Add support for HTTP/2 to improve performance for certain use cases.
   • Integrate HTTP/3 support by leveraging existing QUIC transport libraries for UDP-based communication.