[release] softlan-vpn v0.1.0

First release of softlan-vpn, a low-latency virtual Layer 2 gaming VPN and Ethernet bridge built on QUIC datagrams. This release introduces the initial workspace architecture, crates, and operational components: - lanparty-relay: QUIC-based Layer 2 VPN relay server with room-level isolation, learning switch (CAM table), anti-spoofing MAC validation, safety filters against rogue DHCP servers and IPv6 Router Advertisements, token-bucket rate limiters, and development TLS certificate generation. - lanparty-gateway: Linux Layer 2 gateway bridge utilizing raw AF_PACKET sockets in promiscuous mode to bridge physical LAN segments to remote VPN rooms with carrier checking and datagram budget enforcement. - lanparty-client-win: Windows client CLI and session engine integrating TAP-Windows6 adapter I/O, scoped IP route management (relay host route pinning, default route suppression, metric configuration), and real-time terminal diagnostics. - lanparty-proto, lanparty-ctrl, lanparty-obs, lanparty-net: Protocol primitives, control stream codec, observability reporting, and network resolution helpers. Initial release is documented in CHANGELOG.md adhering to Keep a Changelog and Semantic Versioning. Test Plan: - `just clippy` -- passed - `just fmt` -- passed - `just test` -- passed (118 tests across all crates) - `git diff --cached --check` -- passed Refs: CHANGELOG.md "[0.1.0]", AGENTS.md "Versioning Policy"
justfile, AGENTS.md
2026-08-16 10:39:04 +02:00 · 2026-08-16 10:36:27 +02:00 · 2026-08-16 10:33:28 +02:00
23 changed files with 669 additions and 346 deletions
@@ -0,0 +1,19 @@
+# Agent Instructions
+
+## Commit Policy
+
+Automatically commit changes once a full feature, bugfix, refactor, or other
+coherent unit of work is finished. Do not wait for the user to ask for a commit.
+
+## Versioning Policy
+
+Only update the version, when the user explicitly asks for it.
+
+### Guidelines for how to update the version
+
+1. Use `cargo set-version` to bump the version. Decide, based on the actual
+   changes, based on semver semantics, if major, minor or patch needs to be
+   bumped.
+2. Update the CHANGELOG.md file accordingly.
+3. Create a release commit.
+4. Tag the release commit in the style of previous versioning tags.
@@ -0,0 +1,47 @@
+# Changelog
+
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
+and this project adheres to
+[Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+## [Unreleased]
+
+## [0.1.0] - 2026-08-16
+
+### Added
+
+- **QUIC-based Layer 2 VPN Relay (`lanparty-relay`)**:
+  - Room-isolated virtual Layer 2 Ethernet switching over QUIC datagrams
+    (`quinn` / `rustls`).
+  - Learning switch (CAM table) for unicast frame forwarding and
+    broadcast/multicast flooding.
+  - L2 safety filters: client source MAC anti-spoofing, rogue DHCPv4/DHCPv6
+    server reply filtering, IPv6 Router Advertisement suppression (including
+    behind extension headers), IPv6 fragment filtering, remote VLAN tag
+    filtering, and malformed frame rejection.
+  - Token-bucket rate limiting for broadcast, unknown unicast, and total client
+    bandwidth.
+  - Development TLS certificate generation helper.
+- **Linux Physical Gateway Bridge (`lanparty-gateway`)**:
+  - Promiscuous `AF_PACKET` raw socket bridge connecting local physical LAN
+    networks to virtual relay rooms.
+  - Ingress/egress datagram budget enforcement, carrier validation, and
+    self-injection filtering.
+- **Windows Client (`lanparty-client-win`, `lanparty-client-core`,
+  `lanparty-client-tap`, `lanparty-client-route`)**:
+  - TAP-Windows6 adapter management and Ethernet frame I/O.
+  - Scoped Windows IP route management: relay host route pinning, TAP default
+    route suppression, and interface metric configuration.
+  - Virtual MAC persistence and reconnect handling.
+  - Real-time diagnostic reporting for RTT, LAN DHCP lease state, gateway
+    presence, and frame flow counters.
+- **Shared Infrastructure**:
+  - Protocol primitives (`lanparty-proto`) for datagram framing, MTU
+    negotiation, and safety classifications.
+  - Control plane (`lanparty-ctrl`) for room admission, peer lifecycle events,
+    and stats snapshots.
+  - Observability suite (`lanparty-obs`) for structured frame logging and
+    diagnostic formatting.
+  - Network address resolution utilities (`lanparty-net`).
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@@ -181,9 +181,9 @@ dependencies = [

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 [[package]]
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 dependencies = [
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 "quote",
- "syn 2.0.119",
+ "syn 3.0.3",
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 [[package]]
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 [[package]]
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 [[package]]
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@@ -716,9 +716,9 @@ checksum = "a89322df9ebe1c1578d689c92318e070967d1042b512afbe49518723f4e6d5cd"

 [[package]]
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 [[package]]
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@@ -836,9 +836,9 @@ dependencies = [

 [[package]]
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+version = "0.14.9"
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@@ -888,9 +888,9 @@ dependencies = [

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@@ -914,9 +914,9 @@ dependencies = [

 [[package]]
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@@ -951,9 +951,9 @@ checksum = "f87165f0995f63a9fbeea62b64d10b4d9d8e78ec6d7d51fb2125fda7bb36788f"

 [[package]]
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 [[package]]
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@@ -1177,9 +1177,9 @@ dependencies = [

 [[package]]
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@@ -1237,13 +1237,13 @@ dependencies = [

 [[package]]
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 dependencies = [
 "proc-macro2",
 "quote",
- "syn 2.0.119",
+ "syn 3.0.3",
 ]

 [[package]]
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 [[package]]
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@@ -1315,9 +1315,9 @@ dependencies = [

 [[package]]
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@@ -1325,9 +1325,9 @@ dependencies = [

 [[package]]
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@@ -1338,9 +1338,9 @@ dependencies = [

 [[package]]
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 dependencies = [
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@@ -20,15 +20,15 @@ edition = "2024"
 [workspace.dependencies]
 anyhow = "1"
 bytes = "1"
-clap = { version = "4.6.1", features = ["derive"] }
-getrandom = "0.4.2"
+clap = { version = "4.6.6", features = ["derive"] }
+getrandom = "0.4.3"
 libc = "0.2"
-quinn = "0.11.9"
-rcgen = "0.14.8"
+quinn = "0.11.11"
+rcgen = "0.14.9"
 rustls = { version = "0.23", default-features = false, features = ["ring", "std"] }
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"
 thiserror = "2"
-tokio = { version = "1.52.3", features = ["macros", "net", "rt-multi-thread", "signal", "sync", "time"] }
+tokio = { version = "1.53.1", features = ["macros", "net", "rt-multi-thread", "signal", "sync", "time"] }
 tracing = "0.1"
 windows-sys = "0.61.2"
@@ -1,14 +1,23 @@
+# PLAN
+
 What I want to do:

-A simple one-click Layer 2 tunnel software (Windows 11 client) to bridge people who cannot participate in person at a LAN party to the LAN party. And a simple server endpoint (Linux) software that runs physically at the LAN party and bridges the tunneled traffic and the real LAN network.
+A simple one-click Layer 2 tunnel software (Windows 11 client) to bridge people
+who cannot participate in person at a LAN party to the LAN party. And a simple
+server endpoint (Linux) software that runs physically at the LAN party and
+bridges the tunneled traffic and the real LAN network.

-I already talked a bit with different AIs about how to do this, here's the current plan:
+I already talked a bit with different AIs about how to do this, here's the
+current plan:

-# LAN Party Tunnel Plan
+## LAN Party Tunnel Plan

 Build a **TAP-based L2-over-QUIC tunnel**.

-The remote Windows client gets a real virtual Ethernet adapter. Ethernet frames from that adapter are sent over QUIC to a public relay. The relay forwards them to a Linux gateway at the LAN party. The Linux gateway injects those frames onto the physical LAN and captures replies.
+The remote Windows client gets a real virtual Ethernet adapter. Ethernet frames
+from that adapter are sent over QUIC to a public relay. The relay forwards them
+to a Linux gateway at the LAN party. The Linux gateway injects those frames onto
+the physical LAN and captures replies.

 ```text
 Windows game
@@ -21,13 +30,10 @@ Windows game
  ⇄ physical Ethernet LAN
 ```

-No WireGuard.
-No Npcap.
-No Windows bridge.
-No packet rewriting from the user’s real NIC.
-No tunnel fragmentation for MVP.
+No WireGuard. No Npcap. No Windows bridge. No packet rewriting from the user’s
+real NIC. No tunnel fragmentation for MVP.

-## Goal
+### Goal

 The remote player should do this:

@@ -53,11 +59,12 @@ The public server does this:
 lanparty-relay --listen 443/udp
 ```

-UDP/443 is a good default, but the port must be configurable because some networks block QUIC/UDP.
+UDP/443 is a good default, but the port must be configurable because some
+networks block QUIC/UDP.

-## Components
+### Components

-### 1. Windows client: `lanparty-client.exe`
+#### 1. Windows client: `lanparty-client.exe`

 Written in Rust.

@@ -75,9 +82,13 @@ Responsibilities:
 - keep the relay connection routed through the real internet NIC
 ```

-Use a real TAP/Ethernet adapter. `tap-windows6` is an NDIS TAP-Windows driver used by OpenVPN and other apps, which is the right class of device here because we need Ethernet frames, not just IP packets. ([GitHub][1])
+Use a real TAP/Ethernet adapter. `tap-windows6` is an NDIS TAP-Windows driver
+used by OpenVPN and other apps, which is the right class of device here because
+we need Ethernet frames, not just IP packets. ([GitHub][1])

-Do **not** use Wintun for this design. Wintun is L3/TUN-style and does not give you the Ethernet/L2 behavior needed for ARP, DHCP, broadcast discovery, and old LAN games.
+Do **not** use Wintun for this design. Wintun is L3/TUN-style and does not give
+you the Ethernet/L2 behavior needed for ARP, DHCP, broadcast discovery, and old
+LAN games.

 The TAP adapter is the remote player’s LAN-party identity.

@@ -88,7 +99,7 @@ Game sends ARP/broadcast/multicast through TAP
 Client tunnels the Ethernet frames
 ```

-### 2. Linux gateway: `lanparty-gateway`
+#### 2. Linux gateway: `lanparty-gateway`

 Runs on the physical LAN party machine.

@@ -104,15 +115,23 @@ Responsibilities:
 - periodically refresh switch CAM table entries
 ```

-Use Linux `AF_PACKET` / `SOCK_RAW` on the real wired NIC. Packet sockets operate at device-driver / OSI Layer 2 level, and `SOCK_RAW` includes the link-layer header, which is exactly what we need for Ethernet frames. ([man7.org][2])
+Use Linux `AF_PACKET` / `SOCK_RAW` on the real wired NIC. Packet sockets operate
+at device-driver / OSI Layer 2 level, and `SOCK_RAW` includes the link-layer
+header, which is exactly what we need for Ethernet frames. ([man7.org][2])

-For MVP, run as root. Later, reduce privileges. Opening raw sockets and changing/promiscuous network behavior needs elevated networking privileges; `CAP_NET_ADMIN` covers things like setting promiscuous mode, and `CAP_NET_RAW` covers raw packet access. ([man7.org][3])
+For MVP, run as root. Later, reduce privileges. Opening raw sockets and
+changing/promiscuous network behavior needs elevated networking privileges;
+`CAP_NET_ADMIN` covers things like setting promiscuous mode, and `CAP_NET_RAW`
+covers raw packet access. ([man7.org][3])

-No Linux bridge is needed for MVP. No `br0`. No moving the host’s IP from `eth0` to a bridge. The gateway daemon directly captures and injects frames on the physical NIC.
+No Linux bridge is needed for MVP. No `br0`. No moving the host’s IP from `eth0`
+to a bridge. The gateway daemon directly captures and injects frames on the
+physical NIC.

-Wired Ethernet only. No Wi-Fi gateway mode for MVP. Managed Wi-Fi NICs are not reliable for arbitrary source-MAC injection.
+Wired Ethernet only. No Wi-Fi gateway mode for MVP. Managed Wi-Fi NICs are not
+reliable for arbitrary source-MAC injection.

-### 3. Public relay: `lanparty-relay`
+#### 3. Public relay: `lanparty-relay`

 Runs on VPS/public server.

@@ -139,7 +158,7 @@ gateway → outbound QUIC → relay

 No port forwarding. No NAT traversal pain. Direct P2P can come later.

-## Transport
+### Transport

 Use QUIC.

@@ -158,11 +177,16 @@ disconnect reason
 future auth
 ```

-Use QUIC DATAGRAM for Ethernet frames. QUIC DATAGRAM is specifically the unreliable datagram extension for QUIC, which fits Ethernet/game traffic better than reliable streams because old frames should not block newer frames. ([IETF Datatracker][4])
+Use QUIC DATAGRAM for Ethernet frames. QUIC DATAGRAM is specifically the
+unreliable datagram extension for QUIC, which fits Ethernet/game traffic better
+than reliable streams because old frames should not block newer frames. ([IETF
+Datatracker][4])

-Rust QUIC implementation: start with `quinn`. It exposes `Connection::max_datagram_size()`, which returns the maximum datagram payload size or `None` if datagrams are unsupported/disabled. ([Docs.rs][5])
+Rust QUIC implementation: start with `quinn`. It exposes
+`Connection::max_datagram_size()`, which returns the maximum datagram payload
+size or `None` if datagrams are unsupported/disabled. ([Docs.rs][5])

-## No fragmentation for MVP
+### No fragmentation for MVP

 Do **not** fragment Ethernet frames inside the overlay.

@@ -200,9 +224,10 @@ tap_mtu <= quic_max_datagram_size
           - safety_margin
 ```

-No fragment table. No reassembly timeout. No “one lost fragment kills the whole Ethernet frame.” Add fragmentation later only if testing proves it is necessary.
+No fragment table. No reassembly timeout. No “one lost fragment kills the whole
+Ethernet frame.” Add fragmentation later only if testing proves it is necessary.

-## Overlay frame format
+### Overlay frame format

 Keep the outer routing header small and stable.

@@ -226,13 +251,16 @@ clear routing header
 encrypted Ethernet payload
 ```

-MVP can skip payload encryption beyond QUIC, but the wire format should not make later E2E encryption painful.
+MVP can skip payload encryption beyond QUIC, but the wire format should not make
+later E2E encryption painful.

-## Trust model
+### Trust model

 MVP relay sees plaintext Ethernet frames.

-QUIC encrypts traffic on the wire, but because the relay terminates QUIC connections, it decrypts frames from clients and re-encrypts them to the gateway.
+QUIC encrypts traffic on the wire, but because the relay terminates QUIC
+connections, it decrypts frames from clients and re-encrypts them to the
+gateway.

 That is acceptable for a LAN-party MVP, but it should be explicitly documented.

@@ -246,7 +274,7 @@ relay only sees room id, peer id, size, timing

 Do not retrofit this into a bad packet format later. Reserve the shape now.

-## Switching model
+### Switching model

 Treat the whole thing as a tiny user-space Ethernet switch.

@@ -285,7 +313,7 @@ LAN frames go to matching remote client or all clients if broadcast/multicast

 But MAC learning belongs in the real design.

-## MAC identity
+### MAC identity

 Each Windows client needs a unique locally administered unicast MAC.

@@ -295,7 +323,8 @@ Example range:
 02:xx:xx:xx:xx:xx
 ```

-Generate once per install or per profile. Store it. Configure TAP with it. Announce it during join.
+Generate once per install or per profile. Store it. Configure TAP with it.
+Announce it during join.

 Relay must reject:

@@ -315,11 +344,13 @@ maybe 2 later for weird cases

 This is your responsibility, not the user’s.

-## Linux gateway CAM-table refresh
+### Linux gateway CAM-table refresh

-The physical LAN switch must learn that remote clients’ MACs live behind the gateway port.
+The physical LAN switch must learn that remote clients’ MACs live behind the
+gateway port.

-That happens when the gateway injects frames onto the LAN using the remote client’s source MAC.
+That happens when the gateway injects frames onto the LAN using the remote
+client’s source MAC.

 But switch CAM entries age out. So the gateway should periodically refresh them.

@@ -330,7 +361,8 @@ for each connected remote MAC:
  inject a tiny harmless Ethernet frame with that MAC as source
 ```

-The exact frame can be decided during implementation, but the goal is simple: keep the LAN switch mapping the remote MAC to the gateway’s physical port.
+The exact frame can be decided during implementation, but the goal is simple:
+keep the LAN switch mapping the remote MAC to the gateway’s physical port.

 Phase 1 success criterion:

@@ -340,9 +372,10 @@ remote client MAC appears in the LAN switch MAC table on the gateway port

 If that is false, the L2 illusion is broken.

-## Safety filters
+### Safety filters

-Remote clients must not be allowed to spray arbitrary L2 control-plane junk onto the real LAN.
+Remote clients must not be allowed to spray arbitrary L2 control-plane junk onto
+the real LAN.

 Drop remote → LAN unconditionally:

@@ -368,7 +401,8 @@ Also drop LAN → remote:

 No remote Windows client needs to see switch/control-plane traffic.

-EAPOL is especially important: remote clients should never be able to interfere with 802.1X or port authentication behavior on the physical switch.
+EAPOL is especially important: remote clients should never be able to interfere
+with 802.1X or port authentication behavior on the physical switch.

 Add rate limits:

@@ -379,11 +413,12 @@ Add rate limits:
 - malformed packet disconnect threshold
 ```

-## Windows routing / metric handling
+### Windows routing / metric handling

 The TAP adapter may receive DHCP from the party LAN. That is good.

-But if DHCP gives it a default gateway, Windows might try to route the relay connection through the tunnel itself. That would break the tunnel.
+But if DHCP gives it a default gateway, Windows might try to route the relay
+connection through the tunnel itself. That would break the tunnel.

 Client startup should:

@@ -396,7 +431,8 @@ Client startup should:
 6. detect and neutralize TAP default-route takeover
 ```

-The TAP should be preferred for the party LAN subnet, but it must not steal general internet traffic.
+The TAP should be preferred for the party LAN subnet, but it must not steal
+general internet traffic.

 Also strongly recommend uncommon LAN party subnets:

@@ -409,9 +445,10 @@ bad:  192.168.178.0/24

 Duplicate subnet with a remote user’s home LAN will be painful.

-## Relay placement / latency
+### Relay placement / latency

-Relay-as-data-path is the right MVP. It makes the product work through NAT immediately.
+Relay-as-data-path is the right MVP. It makes the product work through NAT
+immediately.

 But latency becomes:

@@ -421,7 +458,10 @@ client → relay → gateway

 So relay location matters.

-For Europe/Germany-focused usage, put the relay near the expected players and LAN site, e.g. Frankfurt/Nuremberg/Amsterdam depending on hosting. Later, add direct QUIC path attempts with relay fallback, but do not block MVP on NAT traversal.
+For Europe/Germany-focused usage, put the relay near the expected players and
+LAN site, e.g. Frankfurt/Nuremberg/Amsterdam depending on hosting. Later, add
+direct QUIC path attempts with relay fallback, but do not block MVP on NAT
+traversal.

 Design the room protocol so future modes are possible:

@@ -431,7 +471,7 @@ mode = direct-p2p
 mode = direct-failed-relay-fallback
 ```

-## Logging / diagnostics
+### Logging / diagnostics

 Phase 1 should log heavily.

@@ -473,9 +513,9 @@ Broadcast traffic flowing
 Warning: TAP received default route, adjusted metric
 ```

-## Phase plan
+### Phase plan

-### Phase 1: prove the illusion
+#### Phase 1: prove the illusion

 Manual, ugly, real.

@@ -500,7 +540,7 @@ Success criteria:
 - one real LAN game discovers or joins a LAN server
 ```

-### Phase 2: multi-client
+#### Phase 2: multi-client

 ```text
 - multiple Windows clients
@@ -512,7 +552,7 @@ Success criteria:
 - reconnect handling
 ```

-### Phase 3: safety and correctness
+#### Phase 3: safety and correctness

 ```text
 - L2 control-plane filters
@@ -524,7 +564,7 @@ Success criteria:
 - better malformed-frame handling
 ```

-### Phase 4: product UX
+#### Phase 4: product UX

 ```text
 - Windows installer
@@ -536,9 +576,11 @@ Success criteria:
 - logs export button
 ```

-Driver signing and TAP bundling must be validated early. `tap-windows6` is the right kind of driver, but Windows driver installation/signing is a product risk, not something to handwave. ([GitHub][1])
+Driver signing and TAP bundling must be validated early. `tap-windows6` is the
+right kind of driver, but Windows driver installation/signing is a product risk,
+not something to handwave. ([GitHub][1])

-### Phase 5: better security and latency
+#### Phase 5: better security and latency

 ```text
 - invite tokens / auth
@@ -549,7 +591,7 @@ Driver signing and TAP bundling must be validated early. `tap-windows6` is the r
 - regional relay selection
 ```

-## Explicit non-goals
+### Explicit non-goals

 For MVP, do not build:

@@ -565,14 +607,29 @@ For MVP, do not build:
 - full internet VPN mode
 ```

-## One-sentence version
+### One-sentence version

-Build a **Rust Windows TAP client + public QUIC relay + Linux AF_PACKET gateway** that carries one small-MTU Ethernet frame per QUIC datagram, gives each remote player a unique virtual MAC on the real LAN, filters dangerous L2 control traffic, and keeps the physical LAN gateway as the only machine touching the real LAN.
+Build a **Rust Windows TAP client + public QUIC relay + Linux AF_PACKET
+gateway** that carries one small-MTU Ethernet frame per QUIC datagram, gives
+each remote player a unique virtual MAC on the real LAN, filters dangerous L2
+control traffic, and keeps the physical LAN gateway as the only machine touching
+the real LAN.

-[1]: https://github.com/OpenVPN/tap-windows6?utm_source=chatgpt.com "OpenVPN/tap-windows6: Windows TAP driver (NDIS 6)"
-[2]: https://man7.org/linux/man-pages/man7/packet.7.html?utm_source=chatgpt.com "packet(7) - Linux manual page"
-[3]: https://man7.org/linux/man-pages/man7/capabilities.7.html?utm_source=chatgpt.com "capabilities(7) - Linux manual page"
-[4]: https://datatracker.ietf.org/doc/html/rfc9221?utm_source=chatgpt.com "RFC 9221 - An Unreliable Datagram Extension to QUIC"
-[5]: https://docs.rs/quinn/latest/quinn/struct.Connection.html?utm_source=chatgpt.com "Connection in quinn - Rust"
+[1]:
+  <https://github.com/OpenVPN/tap-windows6?utm_source=chatgpt.com>
+  "OpenVPN/tap-windows6: Windows TAP driver (NDIS 6)"
+[2]:
+  <https://man7.org/linux/man-pages/man7/packet.7.html?utm_source=chatgpt.com>
+  "packet(7) - Linux manual page"
+[3]:
+  <https://man7.org/linux/man-pages/man7/capabilities.7.html?utm_source=chatgpt.com>
+  "capabilities(7) - Linux manual page"
+[4]:
+  <https://datatracker.ietf.org/doc/html/rfc9221?utm_source=chatgpt.com>
+  "RFC 9221 - An Unreliable Datagram Extension to QUIC"
+[5]:
+  <https://docs.rs/quinn/latest/quinn/struct.Connection.html?utm_source=chatgpt.com>
+  "Connection in quinn - Rust"

-I want a mono-repo, Rust code, crates into a "crates" folder, one cargo workspace.
+I want a mono-repo, Rust code, crates into a "crates" folder, one cargo
+workspace.
@@ -82,7 +82,8 @@ Windows route-table boundary:
 - unicast IP address snapshots for TAP diagnostics
 - scoped host-route pinning for the relay IP on the pre-TAP interface
 - host-route pin matching for relay-route verification after TAP activation
- reuse of an already-existing matching relay host route without deleting it on exit
+- reuse of an already-existing matching relay host route without deleting it on
+  exit
 - non-Windows builds return a clear unsupported-platform error

 ### `lanparty-client-tap`
@@ -109,9 +110,9 @@ Public relay binary and relay-owned room state:
 - per-peer egress budget checks against the negotiated datagram size
 - reliable `PeerJoined`/`PeerLeft` notifications plus gateway identity in
  welcome messages
- L2 safety filters for invalid-source, jumbo, switch-control, remote VLAN
-  tags, remote IPv6 fragments, IPv4/IPv6 DHCP-server, and IPv6-RA frames,
-  including frames behind ordinary IPv6 extension headers
+- L2 safety filters for invalid-source, jumbo, switch-control, remote VLAN tags,
+  remote IPv6 fragments, IPv4/IPv6 DHCP-server, and IPv6-RA frames, including
+  frames behind ordinary IPv6 extension headers
 - client broadcast/multicast, unknown-unicast, and total bandwidth limiting
 - malformed peer datagram disconnect threshold
 - peer stats control events retained for relay diagnostics
@@ -129,9 +130,9 @@ cargo build --release -p lanparty-relay -p lanparty-gateway
 git diff --check
 ```

-These checks cover the local Rust code and the real client/relay/gateway
-session paths that can run without Windows TAP or LAN hardware. For the Windows
-client build and the manual MVP end-to-end proof, see [TESTING.md](TESTING.md).
+These checks cover the local Rust code and the real client/relay/gateway session
+paths that can run without Windows TAP or LAN hardware. For the Windows client
+build and the manual MVP end-to-end proof, see [TESTING.md](TESTING.md).

 ## Relay

@@ -147,24 +148,24 @@ self-signed development certificate; `--dev-cert-der-out` writes that
 certificate so the gateway and client can pin it in development. Production
 certificate handling remains future work. Ethernet forwarding decisions are
 logged with room, peer, MAC, ethertype, action, drop reason, and target count.
-Safety-policy rejects use the `filtered` action so they are distinguishable
-from malformed/unknown-destination drops and rate limits.
-Malformed peer datagrams log their per-peer count before the relay disconnects
-peers that cross the malformed-datagram threshold.
-Relay egress skips caused by a target peer's smaller datagram budget are logged
-with the ingress peer, target peer, encoded length, and target budget.
-Ingress datagrams larger than the sending peer's negotiated datagram budget are
-dropped before decode/forwarding and logged with `reason=datagram_budget`.
-Unknown unicast from a client is forwarded only to the gateway port; unknown
-unicast from the gateway is dropped instead of flooded to every remote client.
-When a peer joins or leaves, the relay sends a reliable lifecycle control event
-to peers that are still present in the room. Newly joined peers also receive
-`PeerJoined` events for peers that were already present, and catch-up delivery
-is part of the accepted handshake rather than a best-effort follow-up. When a
-client joins, the relay notifies existing peers before the client receives its
-welcome, so gateways can seed client MAC state before that client starts
-sending frames. When a gateway joins, the relay gives the gateway the current
-client list before notifying clients that the gateway is available.
+Safety-policy rejects use the `filtered` action so they are distinguishable from
+malformed/unknown-destination drops and rate limits. Malformed peer datagrams
+log their per-peer count before the relay disconnects peers that cross the
+malformed-datagram threshold. Relay egress skips caused by a target peer's
+smaller datagram budget are logged with the ingress peer, target peer, encoded
+length, and target budget. Ingress datagrams larger than the sending peer's
+negotiated datagram budget are dropped before decode/forwarding and logged with
+`reason=datagram_budget`. Unknown unicast from a client is forwarded only to the
+gateway port; unknown unicast from the gateway is dropped instead of flooded to
+every remote client. When a peer joins or leaves, the relay sends a reliable
+lifecycle control event to peers that are still present in the room. Newly
+joined peers also receive `PeerJoined` events for peers that were already
+present, and catch-up delivery is part of the accepted handshake rather than a
+best-effort follow-up. When a client joins, the relay notifies existing peers
+before the client receives its welcome, so gateways can seed client MAC state
+before that client starts sending frames. When a gateway joins, the relay gives
+the gateway the current client list before notifying clients that the gateway is
+available.

 ### MVP Trust Model

@@ -195,41 +196,38 @@ and completes the control-stream hello/welcome handshake. That startup order
 keeps an invalid, wireless, or unplugged interface from briefly advertising a
 gateway that cannot bridge. Once both sides are ready, it bridges Ethernet
 frames between the relay and wired LAN until shutdown. It captures whole LAN
-frames up to the
-overlay payload-length ceiling before deciding whether they fit the tunnel. It
-never fragments Ethernet frames; LAN frames with invalid source MACs, L2
-control-plane traffic, jumbo frames, frames above the negotiated TAP MTU, or
-encoded datagrams exceeding the negotiated QUIC budget are counted, dropped,
-and logged locally instead of stopping the bridge or consuming relay bandwidth.
-Remote frames received from
-the relay are safety-checked again before LAN injection and must use the
-announced virtual MAC for their source peer, so invalid-source, forged-source,
-L2 control-plane, remote VLAN, DHCP-server, IPv6 Router Advertisement, IPv6
-fragment, jumbo, and over-TAP-MTU frames cannot cross the gateway's final
-physical-LAN boundary even if they reached the gateway over QUIC.
-`--relay` accepts a DNS name or socket address; bare hosts default to UDP/443.
-The gateway rejects Linux interfaces that sysfs identifies as Wi-Fi, and rejects
-wired interfaces whose sysfs carrier state reports no link; managed wireless
-NICs are not supported for the physical LAN bridge.
-It tracks remote-client MACs from relay lifecycle events and periodically emits
-small CAM refresh frames, logged with `reason=periodic`, so the physical
-switch keeps those MACs associated with the gateway port. A newly observed
-client also triggers an immediate CAM refresh frame logged with
-`reason=peer_joined` instead of waiting for the first periodic refresh tick.
-When control events and frame work are both ready, the bridge handles the
-lifecycle event first so first packets after a client joins use the freshest
-remote-MAC state available locally. Gateway
-frame logs include direction, peer id when present, MACs, ethertype/length,
-frame length, action, and drop reason. The gateway also tracks frame/datagram
-counters and periodically sends stats snapshots to the relay. Malformed or runt
-LAN frames are counted and logged as dropped instead of disappearing before
-accounting. It drops unrelated LAN unicast locally once the destination is known
-not to be a connected remote client, so busy LAN traffic is not sent to the
-public relay just to be discarded there. Relay lifecycle events seed and retire
-remote-client MACs for CAM refresh and LAN-destination filtering even before
-that client sends traffic. On shutdown, the gateway sends a best-effort
-disconnect control message before closing QUIC so the relay can report the
-intended reason.
+frames up to the overlay payload-length ceiling before deciding whether they fit
+the tunnel. It never fragments Ethernet frames; LAN frames with invalid source
+MACs, L2 control-plane traffic, jumbo frames, frames above the negotiated TAP
+MTU, or encoded datagrams exceeding the negotiated QUIC budget are counted,
+dropped, and logged locally instead of stopping the bridge or consuming relay
+bandwidth. Remote frames received from the relay are safety-checked again before
+LAN injection and must use the announced virtual MAC for their source peer, so
+invalid-source, forged-source, L2 control-plane, remote VLAN, DHCP-server, IPv6
+Router Advertisement, IPv6 fragment, jumbo, and over-TAP-MTU frames cannot cross
+the gateway's final physical-LAN boundary even if they reached the gateway over
+QUIC. `--relay` accepts a DNS name or socket address; bare hosts default to
+UDP/443. The gateway rejects Linux interfaces that sysfs identifies as Wi-Fi,
+and rejects wired interfaces whose sysfs carrier state reports no link; managed
+wireless NICs are not supported for the physical LAN bridge. It tracks
+remote-client MACs from relay lifecycle events and periodically emits small CAM
+refresh frames, logged with `reason=periodic`, so the physical switch keeps
+those MACs associated with the gateway port. A newly observed client also
+triggers an immediate CAM refresh frame logged with `reason=peer_joined` instead
+of waiting for the first periodic refresh tick. When control events and frame
+work are both ready, the bridge handles the lifecycle event first so first
+packets after a client joins use the freshest remote-MAC state available
+locally. Gateway frame logs include direction, peer id when present, MACs,
+ethertype/length, frame length, action, and drop reason. The gateway also tracks
+frame/datagram counters and periodically sends stats snapshots to the relay.
+Malformed or runt LAN frames are counted and logged as dropped instead of
+disappearing before accounting. It drops unrelated LAN unicast locally once the
+destination is known not to be a connected remote client, so busy LAN traffic is
+not sent to the public relay just to be discarded there. Relay lifecycle events
+seed and retire remote-client MACs for CAM refresh and LAN-destination filtering
+even before that client sends traffic. On shutdown, the gateway sends a
+best-effort disconnect control message before closing QUIC so the relay can
+report the intended reason.

 ## Windows Client

@@ -246,24 +244,21 @@ path depends on TAP-Windows6 and Windows route protection. Non-Windows builds
 are useful for type checking, but they fail before tunnel setup instead of
 joining a room without a TAP adapter. On Windows, the binary connects to the
 relay as `role = client` with a generated locally administered virtual MAC
-persisted in
-`lanparty-client-identity.json`. Before resolving or connecting to the relay,
-it writes the generated tunnel MAC to the selected TAP driver's
+persisted in `lanparty-client-identity.json`. Before resolving or connecting to
+the relay, it writes the generated tunnel MAC to the selected TAP driver's
 `NetworkAddress` registry setting and marks TAP media disconnected. That clears
 stale connected state from a previous crashed run without letting the TAP
 adapter influence relay DNS or route selection. The client then resolves the
 relay endpoint, pins a host route for the resolved relay IP on the current
-pre-TAP interface, verifies that Windows is using that host route, completes
-the control-stream hello/welcome handshake, verifies the host route again after
-TAP activation, and bridges Ethernet frames between the relay and the
-TAP-Windows6 adapter until shutdown. `--relay` accepts a DNS name or socket
-address; bare hosts default to UDP/443.
-TAP frames whose source MAC does not match that generated tunnel MAC are
-dropped locally before they can consume relay bandwidth; the relay still
-enforces the same source-MAC rule.
-If the exact relay host route already exists, the client uses it and leaves it
-alone on exit. The startup status reports whether the relay already has a LAN
-gateway for the room.
+pre-TAP interface, verifies that Windows is using that host route, completes the
+control-stream hello/welcome handshake, verifies the host route again after TAP
+activation, and bridges Ethernet frames between the relay and the TAP-Windows6
+adapter until shutdown. `--relay` accepts a DNS name or socket address; bare
+hosts default to UDP/443. TAP frames whose source MAC does not match that
+generated tunnel MAC are dropped locally before they can consume relay
+bandwidth; the relay still enforces the same source-MAC rule. If the exact relay
+host route already exists, the client uses it and leaves it alone on exit. The
+startup status reports whether the relay already has a LAN gateway for the room.
 `--virtual-mac` can still override the stored identity for manual testing. On
 Windows it sets the TAP IP interface MTU to the relay-selected MTU, marks the
 TAP media connected for the scoped client run, and reports the driver MAC/MTU
@@ -271,40 +266,37 @@ before forwarding frames, along with the TAP interface index/LUID. The client
 applies a scoped TAP interface metric and disables TAP default routes while it
 runs, periodically rechecks that the relay route remains pinned, then restores
 the previous route policy and TAP media status on exit. Startup prints a warning
-when TAP default routes were enabled
-before the scoped protection was applied. Startup still fails before bridging
-if the driver-reported MAC does not match the tunnel identity, because an
-already-initialized Windows TAP adapter may need to be disabled/enabled or
-reinstalled before it reloads the configured `NetworkAddress`.
-If exactly one TAP-Windows6 adapter is installed, the client opens it
-automatically. If multiple TAP-Windows6 adapters are installed, startup fails
-until `--tap-instance-id` selects the intended adapter by NetCfgInstanceId /
-InterfaceGuid. `--list-tap-adapters` prints the TAP adapter ids and exits
-without connecting.
-It prints and reports client diagnostics snapshots with relay reachability,
-LAN-gateway presence, route-pinning, QUIC datagram budget, relay RTT, TAP
-status/IP, broadcast frame flow, frame/datagram counters, and drops. The
-periodic diagnostics refresh the TAP unicast IP so DHCP results that arrive
-after bridging starts become visible in later status lines, preferring a
+when TAP default routes were enabled before the scoped protection was applied.
+Startup still fails before bridging if the driver-reported MAC does not match
+the tunnel identity, because an already-initialized Windows TAP adapter may need
+to be disabled/enabled or reinstalled before it reloads the configured
+`NetworkAddress`. If exactly one TAP-Windows6 adapter is installed, the client
+opens it automatically. If multiple TAP-Windows6 adapters are installed, startup
+fails until `--tap-instance-id` selects the intended adapter by NetCfgInstanceId
+/ InterfaceGuid. `--list-tap-adapters` prints the TAP adapter ids and exits
+without connecting. It prints and reports client diagnostics snapshots with
+relay reachability, LAN-gateway presence, route-pinning, QUIC datagram budget,
+relay RTT, TAP status/IP, broadcast frame flow, frame/datagram counters, and
+drops. The periodic diagnostics refresh the TAP unicast IP so DHCP results that
+arrive after bridging starts become visible in later status lines, preferring a
 non-link-local IPv4 address when Windows reports several TAP addresses. Each
-snapshot also emits short user-facing lines such as relay/gateway connection status,
-relay-route and TAP readiness warnings, DHCP address presence, relay RTT, and
-broadcast-flow confirmation. One-way broadcast diagnostics distinguish frames
-sent toward the LAN from broadcast frames received back from the LAN. Malformed frames
-read from TAP, invalid or unauthorized source-MAC frames, L2 control-plane
-traffic, remote VLAN tags, DHCP server replies, IPv6 Router Advertisements, IPv6
-fragments, jumbo frames, frames above the negotiated TAP MTU, and TAP frames
-whose encoded datagrams exceed the negotiated QUIC budget are counted and
-dropped before relay send without stopping the bridge. Relayed LAN frames are
-also safety-checked before TAP writes, so switch-control traffic,
+snapshot also emits short user-facing lines such as relay/gateway connection
+status, relay-route and TAP readiness warnings, DHCP address presence, relay
+RTT, and broadcast-flow confirmation. One-way broadcast diagnostics distinguish
+frames sent toward the LAN from broadcast frames received back from the LAN.
+Malformed frames read from TAP, invalid or unauthorized source-MAC frames, L2
+control-plane traffic, remote VLAN tags, DHCP server replies, IPv6 Router
+Advertisements, IPv6 fragments, jumbo frames, frames above the negotiated TAP
+MTU, and TAP frames whose encoded datagrams exceed the negotiated QUIC budget
+are counted and dropped before relay send without stopping the bridge. Relayed
+LAN frames are also safety-checked before TAP writes, so switch-control traffic,
 invalid-source frames, jumbo frames, and over-TAP-MTU frames stay out of the
-Windows adapter even if they reached the client over QUIC.
-Misdirected unicast frames not addressed to the client's virtual MAC are also
-counted, skipped, and logged with the drop reason; accepted TAP-to-relay and
-relay-to-TAP frames are logged with direction, peer id, MACs, ethertype/length,
-frame length, action, and drop reason. TAP device read/write errors still stop
-the bridge.
-Relay lifecycle events are logged as they arrive, including gateway joins and
-peer leaves. The client remembers peer identities from join and catch-up events
-and from the initial welcome, so later leave logs can identify a disconnected
-LAN gateway or client MAC when that peer was known.
+Windows adapter even if they reached the client over QUIC. Misdirected unicast
+frames not addressed to the client's virtual MAC are also counted, skipped, and
+logged with the drop reason; accepted TAP-to-relay and relay-to-TAP frames are
+logged with direction, peer id, MACs, ethertype/length, frame length, action,
+and drop reason. TAP device read/write errors still stop the bridge. Relay
+lifecycle events are logged as they arrive, including gateway joins and peer
+leaves. The client remembers peer identities from join and catch-up events and
+from the initial welcome, so later leave logs can identify a disconnected LAN
+gateway or client MAC when that peer was known.
@@ -58,8 +58,8 @@ Windows TAP IPv4:
 - Gateway: Linux machine plugged into the LAN party switch with wired Ethernet.
 - Client: Windows 11 machine with TAP-Windows6 installed.

-Use the same room code everywhere, for example `ROOM1`.
-Start order is relay first, gateway second, Windows client last.
+Use the same room code everywhere, for example `ROOM1`. Start order is relay
+first, gateway second, Windows client last.

 ## Log Capture

@@ -153,8 +153,8 @@ Linux:   ./target/release/lanparty-gateway
 Windows: .\target\release\lanparty-client-win.exe
 ```

-The Windows client must run elevated because it opens TAP and edits routes.
-The gateway usually needs root because it opens an AF_PACKET raw socket.
+The Windows client must run elevated because it opens TAP and edits routes. The
+gateway usually needs root because it opens an AF_PACKET raw socket.

 ## Start The Relay

@@ -196,8 +196,8 @@ sudo ./target/release/lanparty-gateway \
 ```

 Use the real wired LAN interface name for `--interface`. `--iface` is accepted
-as a shorter alias. Do not use Wi-Fi. The gateway fails before joining the
-relay if sysfs reports no Ethernet carrier.
+as a shorter alias. Do not use Wi-Fi. The gateway fails before joining the relay
+if sysfs reports no Ethernet carrier.

 Expected gateway output:

@@ -245,7 +245,8 @@ one explicitly:
 Expected client output:

 ```text
-prepared TAP adapter ... MAC ... configured and media disconnected before relay connect
+prepared TAP adapter ... MAC ... configured and media disconnected before relay
+connect
 relay route pinned before TAP ...
 relay route verified before TAP activation ...
 lanparty-client-win connecting virtual MAC ... to relay ... room ROOM1
@@ -261,11 +262,10 @@ relay event: LAN gateway connected as peer ...

 The route pin line ends with `(created)` or `(already existed)`. Either is OK.
 `already existed` usually means a matching relay host route was already present,
-for example after a previous crashed test run.
-You may also see TAP IPv4/IPv6 MTU, metric, and default-route protection lines
-between the connect and TAP-open lines. Those are expected.
-The lifecycle event may appear after the bridge starts because event logging
-begins once TAP and route protection are ready.
+for example after a previous crashed test run. You may also see TAP IPv4/IPv6
+MTU, metric, and default-route protection lines between the connect and TAP-open
+lines. Those are expected. The lifecycle event may appear after the bridge
+starts because event logging begins once TAP and route protection are ready.

 The first diagnostics line may show `IP unknown`. After DHCP succeeds, a later
 line should show:
@@ -274,8 +274,8 @@ line should show:
 DHCP received: 10.x.x.x
 ```

-If Windows reports both a `169.254.x.x` TAP address and a real LAN IPv4
-address, the client diagnostics should prefer the real LAN address.
+If Windows reports both a `169.254.x.x` TAP address and a real LAN IPv4 address,
+the client diagnostics should prefer the real LAN address.

 ## Verify The Tunnel

@@ -395,10 +395,9 @@ drop_reason=RateLimit

 On gateway `LanToRemote` logs, `UnknownDestination` usually means the gateway
 captured unrelated LAN unicast and dropped it locally instead of sending it to
-the relay.
-`TapMtuExceeded` means a host emitted an Ethernet frame larger than the
-negotiated tunnel MTU; occasional drops can happen while testing software that
-does not honor the smaller adapter MTU yet.
+the relay. `TapMtuExceeded` means a host emitted an Ethernet frame larger than
+the negotiated tunnel MTU; occasional drops can happen while testing software
+that does not honor the smaller adapter MTU yet.

 Drops that should be investigated if they dominate:

@@ -414,8 +413,8 @@ drop_reason=Ipv6Fragment
 ```

 On gateway `RemoteToLan` logs, `UnauthorizedSourceMac` means the relayed peer id
-did not match the client MAC announced by lifecycle events. If it repeats,
-check relay lifecycle logs and duplicate-MAC rejection first.
+did not match the client MAC announced by lifecycle events. If it repeats, check
+relay lifecycle logs and duplicate-MAC rejection first.

 ## Troubleshooting

@@ -454,11 +453,11 @@ If ping fails but DHCP worked, check Windows firewall, the target LAN host
 firewall, and whether the LAN subnet conflicts with the client's home LAN.
 Uncommon LAN subnets such as `10.73.42.0/24` are safer than `192.168.0.0/24`.

-If switch MAC learning does not show the Windows client MAC on the gateway
-port, look for `gateway CAM refresh ... reason=peer_joined` immediately after
-join and `gateway CAM refresh ... reason=periodic` about once per minute after
-that. If those lines are present but the switch still does not learn it, check
-the selected gateway interface and switch port first.
+If switch MAC learning does not show the Windows client MAC on the gateway port,
+look for `gateway CAM refresh ... reason=peer_joined` immediately after join and
+`gateway CAM refresh ... reason=periodic` about once per minute after that. If
+those lines are present but the switch still does not learn it, check the
+selected gateway interface and switch port first.

 ## Cleanup

@@ -21,15 +21,29 @@ use std::{
 use anyhow::{Context, Result, bail};
 use bytes::Bytes;
 use lanparty_ctrl::{
-    CONTROL_LENGTH_PREFIX_LEN, ControlMessage, DisconnectReason, EndpointHello,
-    MAX_CONTROL_MESSAGE_LEN, RELAY_ALPN, RoomCode, ServerWelcome, decode_control_frame,
+    CONTROL_LENGTH_PREFIX_LEN,
+    ControlMessage,
+    DisconnectReason,
+    EndpointHello,
+    MAX_CONTROL_MESSAGE_LEN,
+    RELAY_ALPN,
+    RoomCode,
+    ServerWelcome,
+    decode_control_frame,
    encode_control_message,
 };
 use lanparty_obs::{DropReason, QuicDiagnostics, TunnelStats};
 use lanparty_proto::{
-    EthernetFrame, FrameType, MacAddr, OVERLAY_FLAGS_NONE, decode_datagram, encode_datagram,
-    ethernet_frame_exceeds_tap_mtu, gateway_lan_safety_drop_reason,
-    remote_client_safety_drop_reason, validate_datagram_budget,
+    EthernetFrame,
+    FrameType,
+    MacAddr,
+    OVERLAY_FLAGS_NONE,
+    decode_datagram,
+    encode_datagram,
+    ethernet_frame_exceeds_tap_mtu,
+    gateway_lan_safety_drop_reason,
+    remote_client_safety_drop_reason,
+    validate_datagram_budget,
 };
 use quinn::{ClientConfig, Endpoint, crypto::rustls::QuicClientConfig};
 use rustls::pki_types::CertificateDer;
@@ -6,10 +6,13 @@ edition.workspace = true
 [dependencies]
 anyhow.workspace = true

-[target.'cfg(windows)'.dependencies]
-windows-sys = { workspace = true, features = [
-  "Win32_Foundation",
-  "Win32_NetworkManagement_IpHelper",
-  "Win32_NetworkManagement_Ndis",
-  "Win32_Networking_WinSock",
-] }
+[target."cfg(windows)".dependencies]
+windows-sys = {
+  workspace = true,
+  features = [
+    "Win32_Foundation",
+    "Win32_NetworkManagement_IpHelper",
+    "Win32_NetworkManagement_Ndis",
+    "Win32_Networking_WinSock",
+  ]
+}
@@ -286,9 +286,15 @@ mod windows;
 pub use windows::{PinnedRelayRoute, best_route_to, interface_identity_from_guid, pin_relay_route};
 #[cfg(windows)]
 pub use windows::{
-    ScopedDefaultRoutes, ScopedInterfaceMetric, ScopedInterfaceMtu, interface_metric,
-    interface_mtu, interface_unicast_addresses, set_scoped_default_routes_disabled,
-    set_scoped_interface_metric, set_scoped_interface_mtu,
+    ScopedDefaultRoutes,
+    ScopedInterfaceMetric,
+    ScopedInterfaceMtu,
+    interface_metric,
+    interface_mtu,
+    interface_unicast_addresses,
+    set_scoped_default_routes_disabled,
+    set_scoped_interface_metric,
+    set_scoped_interface_mtu,
 };

 #[cfg(not(windows))]
@@ -1,34 +1,62 @@
 use std::{
-    fmt, io,
+    fmt,
+    io,
    net::{IpAddr, Ipv4Addr, Ipv6Addr},
    ptr::{null, null_mut},
    slice,
 };

 use anyhow::{Context, Result, bail};
-use windows_sys::Win32::{
-    Foundation::{ERROR_OBJECT_ALREADY_EXISTS, ERROR_SUCCESS},
-    NetworkManagement::{
-        IpHelper::{
-            ConvertInterfaceGuidToLuid, ConvertInterfaceLuidToIndex, CreateIpForwardEntry2,
-            DeleteIpForwardEntry2, FreeMibTable, GetBestRoute2, GetIpInterfaceEntry,
-            GetUnicastIpAddressTable, IP_ADDRESS_PREFIX, InitializeIpForwardEntry,
-            InitializeIpInterfaceEntry, MIB_IPFORWARD_ROW2, MIB_IPINTERFACE_ROW,
-            MIB_UNICASTIPADDRESS_ROW, MIB_UNICASTIPADDRESS_TABLE, SetIpInterfaceEntry,
+use windows_sys::{
+    Win32::{
+        Foundation::{ERROR_OBJECT_ALREADY_EXISTS, ERROR_SUCCESS},
+        NetworkManagement::{
+            IpHelper::{
+                ConvertInterfaceGuidToLuid,
+                ConvertInterfaceLuidToIndex,
+                CreateIpForwardEntry2,
+                DeleteIpForwardEntry2,
+                FreeMibTable,
+                GetBestRoute2,
+                GetIpInterfaceEntry,
+                GetUnicastIpAddressTable,
+                IP_ADDRESS_PREFIX,
+                InitializeIpForwardEntry,
+                InitializeIpInterfaceEntry,
+                MIB_IPFORWARD_ROW2,
+                MIB_IPINTERFACE_ROW,
+                MIB_UNICASTIPADDRESS_ROW,
+                MIB_UNICASTIPADDRESS_TABLE,
+                SetIpInterfaceEntry,
+            },
+            Ndis::NET_LUID_LH,
+        },
+        Networking::WinSock::{
+            AF_INET,
+            AF_INET6,
+            AF_UNSPEC,
+            IN_ADDR,
+            IN_ADDR_0,
+            IN6_ADDR,
+            IN6_ADDR_0,
+            RouteProtocolNetMgmt,
+            SOCKADDR_IN,
+            SOCKADDR_IN6,
+            SOCKADDR_IN6_0,
+            SOCKADDR_INET,
        },
-        Ndis::NET_LUID_LH,
-    },
-    Networking::WinSock::{
-        AF_INET, AF_INET6, AF_UNSPEC, IN_ADDR, IN_ADDR_0, IN6_ADDR, IN6_ADDR_0,
-        RouteProtocolNetMgmt, SOCKADDR_IN, SOCKADDR_IN6, SOCKADDR_IN6_0, SOCKADDR_INET,
    },
+    core::GUID,
 };
-use windows_sys::core::GUID;

 use crate::{
-    InterfaceMetricSnapshot, InterfaceMtuSnapshot, InterfaceUnicastAddress, IpInterfaceFamily,
+    InterfaceMetricSnapshot,
+    InterfaceMtuSnapshot,
+    InterfaceUnicastAddress,
+    IpInterfaceFamily,
+    NetworkInterfaceIdentity,
+    RouteSnapshot,
 };
-use crate::{NetworkInterfaceIdentity, RouteSnapshot};

 pub fn interface_identity_from_guid(interface_guid: &str) -> Result<NetworkInterfaceIdentity> {
    let guid = parse_interface_guid(interface_guid)?;
@@ -7,11 +7,14 @@ edition.workspace = true
 anyhow.workspace = true
 lanparty-proto = { path = "../lanparty-proto" }

-[target.'cfg(windows)'.dependencies]
-windows-sys = { workspace = true, features = [
-  "Win32_Foundation",
-  "Win32_Security",
-  "Win32_Storage_FileSystem",
-  "Win32_System_IO",
-  "Win32_System_Registry",
-] }
+[target."cfg(windows)".dependencies]
+windows-sys = {
+  workspace = true,
+  features = [
+    "Win32_Foundation",
+    "Win32_Security",
+    "Win32_Storage_FileSystem",
+    "Win32_System_IO",
+    "Win32_System_Registry",
+  ]
+}
@@ -8,25 +8,51 @@ use anyhow::{Context, Result, bail};
 use lanparty_proto::MacAddr;
 use windows_sys::Win32::{
    Foundation::{
-        CloseHandle, ERROR_FILE_NOT_FOUND, ERROR_MORE_DATA, ERROR_NO_MORE_ITEMS, ERROR_SUCCESS,
-        GENERIC_READ, GENERIC_WRITE, HANDLE, INVALID_HANDLE_VALUE,
+        CloseHandle,
+        ERROR_FILE_NOT_FOUND,
+        ERROR_MORE_DATA,
+        ERROR_NO_MORE_ITEMS,
+        ERROR_SUCCESS,
+        GENERIC_READ,
+        GENERIC_WRITE,
+        HANDLE,
+        INVALID_HANDLE_VALUE,
    },
    Storage::FileSystem::{
-        CreateFileW, FILE_ATTRIBUTE_SYSTEM, FILE_SHARE_READ, FILE_SHARE_WRITE, OPEN_EXISTING,
-        ReadFile, WriteFile,
+        CreateFileW,
+        FILE_ATTRIBUTE_SYSTEM,
+        FILE_SHARE_READ,
+        FILE_SHARE_WRITE,
+        OPEN_EXISTING,
+        ReadFile,
+        WriteFile,
    },
    System::{
        IO::DeviceIoControl,
        Registry::{
-            HKEY, HKEY_LOCAL_MACHINE, KEY_READ, KEY_SET_VALUE, REG_SZ, RegCloseKey, RegEnumKeyExW,
-            RegOpenKeyExW, RegQueryValueExW, RegSetValueExW,
+            HKEY,
+            HKEY_LOCAL_MACHINE,
+            KEY_READ,
+            KEY_SET_VALUE,
+            REG_SZ,
+            RegCloseKey,
+            RegEnumKeyExW,
+            RegOpenKeyExW,
+            RegQueryValueExW,
+            RegSetValueExW,
        },
    },
 };

 use crate::{
-    TAP_ADAPTER_KEY, TapAdapterInfo, is_tap_component_id, tap_ioctl_get_mac, tap_ioctl_get_mtu,
-    tap_ioctl_set_media_status, tap_network_address_value, validate_tap_ethernet_frame,
+    TAP_ADAPTER_KEY,
+    TapAdapterInfo,
+    is_tap_component_id,
+    tap_ioctl_get_mac,
+    tap_ioctl_get_mtu,
+    tap_ioctl_set_media_status,
+    tap_network_address_value,
+    validate_tap_ethernet_frame,
 };

 #[derive(Debug)]
@@ -14,5 +14,5 @@ lanparty-obs = { path = "../lanparty-obs" }
 lanparty-proto = { path = "../lanparty-proto" }
 tokio.workspace = true

-[target.'cfg(windows)'.dependencies]
+[target."cfg(windows)".dependencies]
 lanparty-client-route = { path = "../lanparty-client-route" }
@@ -12,14 +12,23 @@ use std::{sync::mpsc, thread, time::Duration};
 use anyhow::{Context, Result, bail};
 use clap::Parser;
 use lanparty_client_core::{
-    ClientIdentity, ClientIdentityStore, ClientSession, ClientSessionConfig, connect_client,
+    ClientIdentity,
+    ClientIdentityStore,
+    ClientSession,
+    ClientSessionConfig,
+    connect_client,
 };
 #[cfg(windows)]
 use lanparty_client_core::{ClientReceiveOutcome, ClientRelayIo};
 #[cfg(windows)]
 use lanparty_client_route::{
-    IpInterfaceFamily, NetworkInterfaceIdentity, PinnedRelayRoute, RouteSnapshot,
-    ScopedDefaultRoutes, ScopedInterfaceMetric, ScopedInterfaceMtu,
+    IpInterfaceFamily,
+    NetworkInterfaceIdentity,
+    PinnedRelayRoute,
+    RouteSnapshot,
+    ScopedDefaultRoutes,
+    ScopedInterfaceMetric,
+    ScopedInterfaceMtu,
 };
 #[cfg(windows)]
 use lanparty_client_tap::TapAdapter;
@@ -1263,11 +1272,12 @@ mod tests {
        time::{SystemTime, UNIX_EPOCH},
    };

-    use super::*;
    use lanparty_ctrl::{DisconnectReason, PeerInfo};
    use lanparty_net::DEFAULT_RELAY_PORT;
    use lanparty_obs::{QuicDiagnostics, TunnelStats};

+    use super::*;
+
    #[cfg(not(windows))]
    #[test]
    fn rejects_runtime_on_non_windows() {
@@ -9,8 +9,12 @@ use std::{fmt, str::FromStr};
 mod codec;

 pub use codec::{
-    CONTROL_LENGTH_PREFIX_LEN, ControlCodecError, MAX_CONTROL_MESSAGE_LEN,
-    complete_control_frame_len, decode_control_frame, encode_control_message,
+    CONTROL_LENGTH_PREFIX_LEN,
+    ControlCodecError,
+    MAX_CONTROL_MESSAGE_LEN,
+    complete_control_frame_len,
+    decode_control_frame,
+    encode_control_message,
 };
 pub use lanparty_obs::TunnelStats;
 use lanparty_proto::{MIN_USEFUL_TAP_MTU, MacAddr, MtuError, recommended_tap_mtu};
@@ -23,27 +23,42 @@ use anyhow::{Context, Result, bail};
 use bytes::Bytes;
 use clap::Parser;
 use lanparty_ctrl::{
-    CONTROL_LENGTH_PREFIX_LEN, ControlMessage, DisconnectReason, EndpointHello,
-    MAX_CONTROL_MESSAGE_LEN, PeerInfo, RELAY_ALPN, Role, RoomCode, ServerWelcome,
-    decode_control_frame, encode_control_message,
+    CONTROL_LENGTH_PREFIX_LEN,
+    ControlMessage,
+    DisconnectReason,
+    EndpointHello,
+    MAX_CONTROL_MESSAGE_LEN,
+    PeerInfo,
+    RELAY_ALPN,
+    Role,
+    RoomCode,
+    ServerWelcome,
+    decode_control_frame,
+    encode_control_message,
 };
 use lanparty_net::RelayEndpoint;
 use lanparty_obs::{DropReason, TunnelStats};
 #[cfg(target_os = "linux")]
 use lanparty_obs::{FrameAction, FrameDirection, FrameLog};
 use lanparty_proto::{
-    EthernetFrame, FrameType, MacAddr, OVERLAY_FLAGS_NONE, decode_datagram, encode_datagram,
-    ethernet_frame_exceeds_tap_mtu, gateway_lan_safety_drop_reason,
-    remote_client_safety_drop_reason, validate_datagram_budget,
+    EthernetFrame,
+    FrameType,
+    MacAddr,
+    OVERLAY_FLAGS_NONE,
+    decode_datagram,
+    encode_datagram,
+    ethernet_frame_exceeds_tap_mtu,
+    gateway_lan_safety_drop_reason,
+    remote_client_safety_drop_reason,
+    validate_datagram_budget,
 };
+#[cfg(target_os = "linux")]
+pub use packet::PacketSocket;
 use quinn::{ClientConfig, Endpoint, crypto::rustls::QuicClientConfig};
 use rustls::pki_types::CertificateDer;
 #[cfg(target_os = "linux")]
 use tokio::io::unix::AsyncFd;

-#[cfg(target_os = "linux")]
-pub use packet::PacketSocket;
-
 const MAX_CONTROL_FRAME_LEN: usize = CONTROL_LENGTH_PREFIX_LEN + MAX_CONTROL_MESSAGE_LEN;
 const DISCONNECT_DRAIN_TIMEOUT: Duration = Duration::from_millis(250);
 #[cfg(target_os = "linux")]
@@ -1146,7 +1161,7 @@ mod tests {
        let help = String::from_utf8(help).unwrap();

        assert!(
-            help.contains("[aliases: --iface]"),
+            help.contains("[alias: --iface]") || help.contains("[aliases: --iface]"),
            "gateway help should advertise --iface alias:\n{help}"
        );
    }
@@ -1,6 +1,7 @@
 use std::{
    ffi::CString,
-    fs, io,
+    fs,
+    io,
    os::fd::{AsRawFd, FromRawFd, OwnedFd, RawFd},
    path::Path,
 };
@@ -11,22 +11,46 @@ mod overlay;
 mod safety;

 pub use ethernet::{
-    ETHERNET_HEADER_LEN, EthernetFrame, MAX_STANDARD_ETHERNET_FRAME_LEN,
-    MAX_STANDARD_ETHERNET_PAYLOAD_LEN, MIN_ETHERNET_FRAME_LEN,
+    ETHERNET_HEADER_LEN,
+    EthernetFrame,
+    MAX_STANDARD_ETHERNET_FRAME_LEN,
+    MAX_STANDARD_ETHERNET_PAYLOAD_LEN,
+    MIN_ETHERNET_FRAME_LEN,
 };
 pub use mac::{MacAddr, MacParseError};
 pub use mtu::{
-    DEFAULT_DATAGRAM_SAFETY_MARGIN, DEFAULT_TAP_MTU, MIN_USEFUL_TAP_MTU, MtuError,
-    ethernet_frame_exceeds_tap_mtu, max_ethernet_frame_len_for_tap_mtu, max_tap_mtu_for_datagram,
+    DEFAULT_DATAGRAM_SAFETY_MARGIN,
+    DEFAULT_TAP_MTU,
+    MIN_USEFUL_TAP_MTU,
+    MtuError,
+    ethernet_frame_exceeds_tap_mtu,
+    max_ethernet_frame_len_for_tap_mtu,
+    max_tap_mtu_for_datagram,
    recommended_tap_mtu,
 };
 pub use overlay::{
-    FrameType, OVERLAY_FLAGS_NONE, OVERLAY_HEADER_LEN, OVERLAY_MAGIC, OVERLAY_VERSION,
-    OverlayHeader, OverlayPacket, ProtoError, decode_datagram, encode_datagram,
+    FrameType,
+    OVERLAY_FLAGS_NONE,
+    OVERLAY_HEADER_LEN,
+    OVERLAY_MAGIC,
+    OVERLAY_VERSION,
+    OverlayHeader,
+    OverlayPacket,
+    ProtoError,
+    decode_datagram,
+    encode_datagram,
    validate_datagram_budget,
 };
 pub use safety::{
-    ETHERTYPE_8021AD, ETHERTYPE_8021Q, ETHERTYPE_EAPOL, ETHERTYPE_IPV4, ETHERTYPE_IPV6,
-    ETHERTYPE_LLDP, ETHERTYPE_QINQ, ETHERTYPE_SLOW_PROTOCOLS, EthernetSafetyDrop,
-    gateway_lan_safety_drop_reason, remote_client_safety_drop_reason,
+    ETHERTYPE_8021AD,
+    ETHERTYPE_8021Q,
+    ETHERTYPE_EAPOL,
+    ETHERTYPE_IPV4,
+    ETHERTYPE_IPV6,
+    ETHERTYPE_LLDP,
+    ETHERTYPE_QINQ,
+    ETHERTYPE_SLOW_PROTOCOLS,
+    EthernetSafetyDrop,
+    gateway_lan_safety_drop_reason,
+    remote_client_safety_drop_reason,
 };
@@ -9,18 +9,28 @@ mod server;

 use std::{collections::HashMap, time::Instant};

+pub use config::{ConfigError, DEFAULT_RELAY_PORT, ListenEndpoint, RelayArgs, RelayConfig};
 use lanparty_ctrl::{
-    ControlError, EndpointHello, PeerInfo, Reject, RejectReason, Role, RoomCode, ServerWelcome,
+    ControlError,
+    EndpointHello,
+    PeerInfo,
+    Reject,
+    RejectReason,
+    Role,
+    RoomCode,
+    ServerWelcome,
 };
 use lanparty_obs::{DropReason, FrameAction};
 use lanparty_proto::{
-    EthernetFrame, MacAddr, ethernet_frame_exceeds_tap_mtu, gateway_lan_safety_drop_reason,
-    recommended_tap_mtu, remote_client_safety_drop_reason,
+    EthernetFrame,
+    MacAddr,
+    ethernet_frame_exceeds_tap_mtu,
+    gateway_lan_safety_drop_reason,
+    recommended_tap_mtu,
+    remote_client_safety_drop_reason,
 };
-use thiserror::Error;
-
-pub use config::{ConfigError, DEFAULT_RELAY_PORT, ListenEndpoint, RelayArgs, RelayConfig};
 pub use server::RelayServer;
+use thiserror::Error;

 pub const DEFAULT_MAX_CLIENTS_PER_ROOM: usize = 16;
 const MEBIBYTE: u64 = 1024 * 1024;
@@ -769,9 +779,10 @@ fn reject_control_error(error: ControlError) -> Reject {
 mod tests {
    use std::time::{Duration, Instant};

-    use super::*;
    use lanparty_proto::MAX_STANDARD_ETHERNET_FRAME_LEN;

+    use super::*;
+
    fn room() -> RoomCode {
        RoomCode::new("ABCD").unwrap()
    }
@@ -1,20 +1,42 @@
-use std::{fs, net::SocketAddr, path::Path, sync::Arc};
+use std::{collections::HashMap, fs, net::SocketAddr, path::Path, sync::Arc};

 use anyhow::{Context, Result, anyhow, bail};
 use bytes::Bytes;
 use lanparty_ctrl::{
-    CONTROL_LENGTH_PREFIX_LEN, ControlCodecError, ControlMessage, DisconnectReason, EndpointHello,
-    MAX_CONTROL_MESSAGE_LEN, PeerInfo, RELAY_ALPN, Reject, RejectReason, Role, RoomCode,
-    ServerWelcome, decode_control_frame, encode_control_message,
+    CONTROL_LENGTH_PREFIX_LEN,
+    ControlCodecError,
+    ControlMessage,
+    DisconnectReason,
+    EndpointHello,
+    MAX_CONTROL_MESSAGE_LEN,
+    PeerInfo,
+    RELAY_ALPN,
+    Reject,
+    RejectReason,
+    Role,
+    RoomCode,
+    ServerWelcome,
+    decode_control_frame,
+    encode_control_message,
 };
 use lanparty_obs::{DropReason, FrameDirection, FrameLog, TunnelStats};
 use lanparty_proto::{
-    EthernetFrame, FrameType, OVERLAY_FLAGS_NONE, decode_datagram, encode_datagram,
+    EthernetFrame,
+    FrameType,
+    OVERLAY_FLAGS_NONE,
+    decode_datagram,
+    encode_datagram,
+};
+use quinn::{
+    Endpoint,
+    Incoming,
+    RecvStream,
+    SendStream,
+    ServerConfig,
+    TransportConfig,
+    crypto::rustls::QuicServerConfig,
 };
-use quinn::crypto::rustls::QuicServerConfig;
-use quinn::{Endpoint, Incoming, RecvStream, SendStream, ServerConfig, TransportConfig};
 use rustls::pki_types::{CertificateDer, PrivateKeyDer, PrivatePkcs8KeyDer};
-use std::collections::HashMap;
 use tokio::sync::Mutex;

 use crate::{ForwardingDecision, RelayConfig, RoomRegistry};
@@ -1014,13 +1036,17 @@ mod tests {
    use lanparty_ctrl::{RoomCode, decode_control_frame, encode_control_message};
    use lanparty_gateway::{GatewayConfig, connect_gateway};
    use lanparty_proto::{
-        ETHERNET_HEADER_LEN, ETHERTYPE_IPV4, FrameType, MacAddr, decode_datagram, encode_datagram,
+        ETHERNET_HEADER_LEN,
+        ETHERTYPE_IPV4,
+        FrameType,
+        MacAddr,
+        decode_datagram,
+        encode_datagram,
    };
    use quinn::{ClientConfig, crypto::rustls::QuicClientConfig};

-    use crate::{DEFAULT_MAX_CLIENTS_PER_ROOM, ListenEndpoint};
-
    use super::*;
+    use crate::{DEFAULT_MAX_CLIENTS_PER_ROOM, ListenEndpoint};

    const ETHERTYPE_ARP: u16 = 0x0806;
    const ARP_REQUEST: u16 = 1;
@@ -0,0 +1,35 @@
+set positional-arguments
+
+run *args:
+    cargo run -- "$@"
+
+build:
+    cargo build
+
+build-release:
+    cargo build --release
+
+build-production:
+    cargo build --profile production
+
+fmt:
+    cargo +nightly fmt
+    tombi format
+    fd -tf -e md -x prettier --write --prose-wrap always --print-width 80
+    rumdl check --flavor commonmark --fix
+    just --fmt
+
+_fix:
+    cargo fix --workspace --all-targets --all-features
+    cargo clippy --fix --workspace --all-targets --all-features
+
+fix: _fix fmt
+
+clippy:
+    cargo clippy --workspace --all-targets --all-features -- -D warnings
+
+test:
+    cargo test --workspace --all-targets --all-features
+
+clean:
+    cargo clean
@@ -0,0 +1,3 @@
+group_imports = "StdExternalCrate"
+imports_granularity = "Crate"
+imports_layout = "HorizontalVertical"