Add support for XDP/AF_XDP zero-copy integration in shoes #112
Description
Body:
Feature Request / Proposal
Summary:
I propose adding support for XDP/AF_XDP zero-copy packet reception in shoes. The goal is to allow shoes to directly receive packets from a specified port (e.g., 443) using AF_XDP sockets, bypassing the kernel TCP/IP stack for high-performance use cases, while maintaining normal TCP/IP processing for other ports. This would enable a single-port high-performance zero-copy proxy setup for protocols like VLESS, AnyTLS, and HY2.
Motivation:
Improve CPU efficiency for high-throughput TCP/TLS traffic.
Reduce user-space/kernel-space copy overhead.
Allow users to selectively accelerate critical ports (e.g., 443) without affecting other services.
Provide a foundation for integrating kernel TLS offload (kTLS) with shoes in the future.
Proposed Implementation:
Introduce an AF_XDP socket layer in shoes.
Add a TCP/UDP user-space stack to handle packets received from AF_XDP.
Maintain compatibility with the existing transport and application layers (VLESS, AnyTLS, HY2, etc.).
Allow configuration to specify which ports should be redirected to AF_XDP.
Ensure fallback: traffic on non-specified ports continues to use the kernel TCP/IP stack.
Benefits:
CPU usage reduction for high-concurrency TCP/TLS workloads.
Zero-copy packet processing for selected ports.
Flexibility: only accelerate high-priority traffic.
Foundation for future high-performance user-space TLS handling.
Additional Context / References:
Similar zero-copy approaches are commonly used in high-performance proxy servers (e.g., sing-box with AF_XDP experimental implementations).