GSoC Work Product: GNUnet over HTTP/3

Goals of the Project.

This project aimed to implement a new communicator for GNUnet's Transport Next Generation (TNG) using the HTTP/3 protocol.

What I did.

We chose ngtcp2 and nghttp3 for their stability and adherence to RFC standards. I began by studying communicator fundamentals and analyzing relevant code examples. I then created a QUIC communicator using libngtcp2, implementing essential communication features. Building on this, I integrated libnghttp3 to support HTTP/3 layer communication. After establishing basic uni-directional communication, I proceeded to implement bi-directional capabilities. With the help and guidance of my mentors, I completed the above work, including the selection and design of message transmission methods and the implementation of code.

The current state.

We have two branches, dev/shichao/http3 for basic communication and dev/shichao/http3bidirect for bi-directional communication. They can pass the basic tests. However, we found that there were occasional failures during the test. We currently assume that this is caused by the test harness not being able to process the received data packets in time.

What's left to do.

There are still many areas that can be improved in the HTTP/3 communicator, such as using CID map instead of IP address map. In addition, in bi-directional communication, the server's sending rate is slightly lower than the client's transmission rate, and this will be optimized in the future. Finally, integrating the Peer Identity into the TLS handshake in order to authenticate the peers is a natural feature to implement.

What code got merged (or not) upstream.

All the code is available upstream in the master branch and will be available with the next release.

Challenges I Encountered.

Initially, I was unfamiliar with the ngtcp2 and nghttp3 libraries. While there were some examples available, I found limited guidance for more advanced usage. Through careful study and experimentation, I gradually gained a deeper understanding of these libraries. But in this process, I have a deeper understanding of QUIC and HTTP/3 protocols, and also improved my coding skills.