Files
parking_solution/wiki/concepts/device-discovery.md
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julian 355026dcf7 Remove UHPPOTE/ZKTeco; Dingtian is the only access driver
Neither UHPPOTE nor ZKTeco is used — the Dingtian relay controller was chosen
and verified. Remove their code and re-scope the wiki.

Code:
- delete access-uhppote.ts, uhppoted.d.ts, access.ts (zkteco/esp32-relay stubs),
  and the three uhppote-*.mjs hardware test scripts.
- remove the `uhppoted` npm dependency from @parking/devices and @parking/server.
- unregister uhppote/zkteco/esp32-relay from the driver registry; drop their
  exports. Catalog access drivers = dingtian only. Build green (5/5).
- refresh now-stale example comments (registry/interfaces/setup/api) to use
  current examples; keep the two "UHPPOTE blocker" references that explain why
  the precondition capability exists.

Wiki (kept pages, re-scoped):
- uhppote-controller, zkteco-controller -> rejected/historical with callouts;
  uhppote-vs-esp32 -> historical (detection-vs-prevention lens still useful).
- re-point all "current device" framing (standing-decisions, bom, overview,
  open-questions, device-registry, device-discovery, index) to dingtian-relay.
- transferable concepts (network-isolation, event-log-ingestion, barrier-not-a-
  door, threat-model) untouched. Raw source immutable. Links lint clean.
2026-06-14 14:28:52 +02:00

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Markdown

---
type: concept
tags: [parking, architecture, devices, setup]
sources: [parking-system-architecture]
updated: 2026-06-15
---
# Device Discovery
An optional driver capability: **find devices on the LAN** so the admin doesn't have to type
connection details by hand during [[first-run-setup]]. Modeled generically so any driver can
opt in.
> Implementation-derived (from `@parking/devices` + setup API/UI), not the source doc.
## The capability
A driver may implement `DiscoverableDriver` — `discover() => DiscoveredDevice[]`. Each found
device carries an `id`, a `label`, a `config` blob to **auto-fill** the setup form, and `info`
(firmware, MAC, …). The [[device-registry]]'s `isDiscoverable()` guard lets the system treat it
as optional; the setup catalog returns a `discoverable` list of driver ids.
> **No current driver implements discovery.** The [[dingtian-relay]] board uses a fixed IP
> (entered/known at setup). The capability remains for future UDP-discoverable devices (cameras
> via ONVIF, etc.). The worked example below is the (removed) UHPPOTE driver — kept because the
> **broadcast gotchas are transferable** to any UDP discovery we add later.
## UHPPOTE discovery (historical example)
The [[uhppote-controller]] supported discovery natively: a **UDP broadcast** (`get-devices` on
port `60000`) that **every controller on the LAN answers** with its serial, IP, netmask, gateway,
MAC, firmware version, and date. The `uhppoted` lib exposed this as `getDevices(ctx)`; the
(now-removed) `uhppote` driver mapped each result into a `DiscoveredDevice` (serial → id, IP →
host). **Was verified on real hardware** (serial 225088491).
### Broadcast gotchas (learned the hard way — see [[wsl-dev-networking]])
These cost real debugging time; the (removed) `uhppote` driver handled all three, and any future
UDP-discovery driver will need to as well:
1. **Broadcast to the *subnet-directed* address, not the global `255.255.255.255`.** The
`uhppoted` lib only calls `setBroadcast(true)` when the target matches a **local interface's
subnet broadcast** (e.g. `10.0.10.255`). For the global address it skips it, so the `send`
fails with **`EACCES`**. The driver computes the subnet broadcast from `os.networkInterfaces()`.
2. **A host with multiple interfaces must broadcast on *all* subnets.** With several NICs (LAN,
VPN/Tailscale, docker bridges) the controller is on only one. Picking the first interface
misses it; the driver broadcasts on every subnet and dedupes by serial.
3. **For *unicast* ops (status / open), the lib's `Config` broadcast must match the target's
subnet** — it governs reply routing, so a mismatched broadcast makes `getStatus` time out even
though `openDoor` "succeeds". The driver sets the broadcast per the target host's subnet. (This
was the health-check "offline/timeout" bug: a 5 s timeout dropped to 24 ms once fixed.)
Also: concurrent `uhppoted` calls collide on the `:60001` reply-listener port (EACCES / dropped
replies), so the driver **serializes** all controller I/O. Override the broadcast with
`UHPPOTE_BROADCAST` for unusual setups.
## Flow
1. The setup catalog flags `uhppote` as discoverable.
2. Admin clicks **Scan** → `GET /api/setup/discover/:driverId` (admin-only).
3. The server runs `discover()` and **health-checks each found device** so the admin sees
reachability before assigning.
4. Selecting a result **auto-fills serial + host**; the admin then assigns it to a lane.
## Deployment notes
- Discovery is an **L2 broadcast**: the host and controller must share a layer-2 segment. Works
on the isolated device VLAN ([[network-isolation]]). A routed/NAT'd network (e.g. WSL2 NAT mode
— see [[wsl-dev-networking]]) blocks it entirely.
- Discovery shares the same unauthenticated UDP exposure as everything else UHPPOTE — another
reason the controllers live on an isolated VLAN ([[uhppote-udp-protocol]]).
- Cameras (Hikvision/Dahua via ONVIF/WS-Discovery) could implement the same interface later.