[Research/Kernel]: Implement Layer 2 XDP (eXpress Data Path) Dynamic Driver-Level Socket Redirect for Zero-Copy Failov

Problem

Even with standard eBPF transport layer hooks, network packets still must pass through the Linux networking stack software layers before reaching our Go user-space proxy router. At multi-gigabit line-rate traffic speeds, passing data frames up the stack triggers microsecond execution bottlenecks and constraints CPU throughput during massive cluster failovers.

Proposed Solution

Prototype a driver-level connection rerouting engine within cmd/daemon/xdp_failover.c utilizing eBPF XDP (eXpress Data Path) XDP_REDIRECT actions.

• Intercept incoming network data frames directly at the Network Interface Card (NIC) driver ring buffer before the kernel context allocates a single system memory block.
• Map global backend cluster node health states natively inside an active eBPF BPF_MAP_TYPE_HASH configuration ring.
• When an upstream server drop signal triggers, the driver-level eBPF filter must immediately update packet MAC/IP fields natively inside the network card and flush the frame back out (XDP_REDIRECT) to a healthy worker node under < 500 microseconds—completely bypassing the entire host OS kernel memory networking stack.

Alternatives

• Layer 4 transport intercept loops, which are highly defensible but still require full CPU network packet parsing round-trips up the kernel layer stack.

Use Case

Creates the ultimate mathematical performance boundary: line-rate software failover operation execution moving data packets directly on the silicon hardware ring with literal 0ms host OS kernel processing load.

Additional Notes

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Start by reading cmd/daemon/xdp_failover.c and the issue's description of the existing eBPF transport-layer path. Define the prototype around XDP_REDIRECT, backend health state handling, packet MAC/IP updates, and failover routing. Done means packets are redirected to a healthy worker while meeting the stated under-500-microsecond target.