Add the reliable control-plane schema that will run over QUIC streams. This
covers the phase-1 handshake shape without mixing in relay sockets, TAP access,
or gateway packet IO.
The schema includes endpoint hello messages with role, room, MAC, and datagram
budget, plus server welcome, rejection, peer lifecycle, stats, and disconnect
messages. Constructors and validation enforce room-code syntax, client MAC
identity rules, reserved peer IDs, and effective TAP MTU limits. Decoded control
messages can be validated explicitly so serde input cannot silently bypass the
same invariants.
The actual stream codec remains future work; this commit only fixes the typed
contract the codec will carry.
Test Plan:
- cargo fmt --check
- cargo test --workspace
- cargo clippy --workspace --all-targets -- -D warnings
Refs: PLAN.md reliable QUIC control stream requirements
Build the shared protocol contract that the client, gateway, and relay will use
for Ethernet datagrams. The MVP needs these pieces agreed on before socket or
TAP work can be reasoned about safely.
This adds strict MAC parsing and client identity validation, Ethernet header
inspection, fixed overlay datagram encoding and decoding, and MTU helpers for
the no-fragmentation QUIC datagram design. The protocol crate stays
transport-agnostic so platform and network code can depend on it without
pulling in OS-specific behavior.
Remaining work is to put these primitives behind the control-plane handshake,
relay forwarding loop, Windows TAP client, and Linux AF_PACKET gateway.
Test Plan:
- cargo fmt --check
- cargo test --workspace
- cargo clippy --workspace --all-targets -- -D warnings
Refs: PLAN.md Phase 1: prove the illusion
ddidderr
