Split AF_XDP socket implementation from s2n-quic-xdp into its own project/crate

[OliverGavin]

Problem:

More of an opportunity than a problem :)

There are a limited number of options for Rust users who need an AF_XDP socket;

• https://crates.io/crates/xdpilone seems nice and simple but the license isn’t suitable for many
• https://crates.io/crates/xdpsock doesn’t seem to let me use my own maps (also doesn’t seem to be maintained)
• https://crates.io/crates/xsk-rs also doesn’t seem to let me use my own maps?
• https://crates.io/crates/afxdp doesn’t seem to be maintained

But then I see you have made https://crates.io/crates/s2n-quic-xdp which is actively maintained and seems to be attempting to create a safe interface. However, much of this crate is tangled with s2n needs so the lower level APIs are private and not yet documented. There would also be an opportunity to improve on those lower level APIs to make them a little more intuitive and safer.

Solution:

Create a new crate (could be later moved from this project) which offers a safe and general purpose AF_XDP socket implementation with documentation. Optional features to offer integration with Aya could also be considered.

• Does this change what s2n-quic sends over the wire?
  no
• Does this change any public APIs?
  yes

Requirements / Acceptance Criteria:

• RFC links: Links to relevant RFC(s)
• Related Issues: Link any relevant issues
  • Short term ask: Expose lower level AF_XDP socket functions #2404
  • Documentation: Write AF-XDP user guide #2011
• Will the Usage Guide or other documentation need to be updated?
  • yes
• Testing: How will this change be tested? Call out new integration tests, functional tests, or particularly interesting/important unit tests.
  • Existing tests should cover any regressions (assuming they exist). New tests would likely be needed for a general purpose release of the proposed crate.