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feat(gateway): bridge relay and LAN frames

The gateway now runs the actual frame bridge after relay admission. It registers
the AF_PACKET socket with Tokio using AsyncFd, reads valid LAN Ethernet frames
and forwards them as relay datagrams, and writes valid relay Ethernet datagrams
back to the LAN socket.

The packet socket is opened nonblocking so the bridge can shut down cleanly on
Ctrl-C without leaving a blocking recv thread behind. Existing send_ethernet and
recv_ethernet helpers now share the same validation and encoding helpers used by
the bridge.

This still needs a privileged LAN-host smoke test with a real wired interface,
but the compile-time and loopback coverage now include the gateway relay side of
the bridge and the non-root-safe packet-socket validation.

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

Refs: PLAN.md gateway AF_PACKET to relay bridge loop

2026-05-21 18:16:04 +02:00

2.8 KiB

Raw Blame History

softlan-vpn

Monorepo for a Layer 2 over QUIC LAN party bridge.

Workspace crates

lanparty-proto: shared frame format, MAC validation, MTU helpers.
lanparty-ctrl: control-plane messages (join/hello/role/version).
lanparty-obs: shared diagnostics/logging event models.
lanparty-client-core: platform-agnostic client session state.
lanparty-client-win: Windows TAP + route/metric handling binary.
lanparty-gateway: Linux AF_PACKET gateway binary.
lanparty-relay: public QUIC relay binary.

`lanparty-proto`

Transport-agnostic tunnel contract shared by all binaries:

overlay datagram header encoding and decoding
Ethernet frame header parsing
MAC address parsing and identity validation
QUIC datagram to TAP MTU budget helpers

`lanparty-ctrl`

Reliable control-plane schema shared by the QUIC stream handlers:

endpoint hello messages with role, room, MAC, and datagram budget
server welcome, reject, peer lifecycle, stats, and disconnect messages
room-code, role/MAC, peer-id, and effective-MTU validation
length-prefixed JSON control frames for reliable QUIC streams

`lanparty-obs`

Shared diagnostics and structured logging vocabulary:

gateway/relay frame logs with MACs, ethertype, length, peer, and action
tunnel counters shared by control messages and runtime diagnostics
client connectivity/TAP diagnostics and user-facing status messages

`lanparty-relay`

Public relay binary and relay-owned room state:

QUIC endpoint binding and first-stream hello/welcome admission
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
live Ethernet datagram forwarding with no ingress reflection
L2 safety filters for jumbo, switch-control, DHCP-server, and IPv6-RA frames
peer leave cleanup for room membership and MAC indexes

Build

cargo check --workspace

Relay

cargo run -p lanparty-relay -- --listen 443/udp

--listen accepts either a socket address or a UDP port shorthand such as 443/udp. The relay binds a QUIC endpoint, accepts a control-stream hello, replies with welcome or reject, and forwards live Ethernet QUIC datagrams between accepted peers in the same room. It currently uses a generated self-signed development certificate; production certificate and client trust handling remain future work.

Gateway

cargo run -p lanparty-gateway -- \
  --relay 203.0.113.10:443 \
  --server-name lanparty-relay.local \
  --relay-ca-cert relay-cert.der \
  --room ROOM1 \
  --interface eth0

The gateway connects to the relay as role = gateway, completes the control-stream hello/welcome handshake, opens an AF_PACKET socket on the LAN interface, and bridges Ethernet frames between the relay and wired LAN until shutdown.

2.8 KiB Raw Blame History