feat(relay): add Ethernet forwarding decisions

Add socket-free relay forwarding logic for Ethernet datagrams. The future QUIC
relay loop can now ask the room registry which peer IDs should receive a frame
instead of embedding switching policy in network IO code.

Forwarding validates that the ingress peer belongs to the room, drops malformed
Ethernet frames, rejects client frames whose source MAC does not match the MAC
announced during admission, never reflects frames back to ingress, routes known
client unicasts directly, and floods broadcast/multicast or unknown unicast
frames to the other room peers. The decision reports shared observability action
and drop-reason values so the networking layer can log consistently.

This still does not send bytes over QUIC; it only defines the room-local switch
decision that the datagram loop will use.

Test Plan:
- cargo fmt --check
- cargo test --workspace
- cargo clippy --workspace --all-targets -- -D warnings

Refs: PLAN.md Switching model

This commit is contained in:

ddidderr

2026-05-21 17:28:17 +02:00

parent 879cb689a4

commit b3d1a9c046

4 changed files with 250 additions and 1 deletions

									
										README.md
									
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				@@ -45,6 +45,7 @@ Public relay binary and relay-owned room state:

				- room admission for clients and gateways

				- one gateway per room, duplicate client MAC rejection, and room limits

				- stable effective room MTU chosen before Ethernet datagrams flow

				- Ethernet datagram forwarding decisions with no ingress reflection

				## Build