Dingtian input push: HTTP Digest auth + auto-config on assign

Secure the device→backend input push, and configure it automatically when the
admin assigns the device (no manual URL/secret entry).

Auth — HTTP Digest (chosen by hardware testing: the device can't push to a
self-signed HTTPS backend, but does Digest correctly; a URL token is sniffable/
logged):
- digest-auth.ts: MD5 qop=auth challenge/verify, single-use nonces (replay
  resistance). Password never crosses the wire.
- push route: Digest + source-IP allowlist; per-device pushUser/pushPassword from
  lane_devices. Still not behind the SPA cookie/CSRF auth (machine call). The
  signed event log remains the real anti-fraud guarantee.

Auto-config on assign:
- setup assign: for push-capable devices, generate Digest creds, call
  configureInputPush to write them + the push URLs to the device, store the creds
  (password not echoed back). net.ts derives the backend IP on the device's
  subnet (BACKEND_HOST_IP override).
- driver configureInputPush sets auth=2 + creds; PushConfig carries the creds.
- removed the earlier URL-token approach.

Two hard-won device-write bugs fixed in the driver:
- configApi now sets an explicit Content-Length — the device silently ignores
  chunked request bodies (Node's default without Content-Length), so every config
  write looked successful ({"status":0}) but did nothing. This was the root cause
  of the session's "writes don't apply" mystery.
- #writeConfig polls until the change is verified, retrying (the device reboots on
  apply; back-to-back writes were lost). The `pass` field caps at 31 chars, so the
  generated password is 24 hex chars.

Verified on hardware: assign auto-configures the device; all 4 inputs then push
with Digest auth, zero failures. wiki/device-input-flow updated.

apps/server/src/routes/devices.ts

@@ -1,54 +1,82 @@
-import type { FastifyInstance, FastifyRequest } from "fastify";
+import type { FastifyInstance, FastifyReply, FastifyRequest } from "fastify";
+import { eq, laneDevices, type Db } from "@parking/db";
 import { deviceEvents } from "../device-events.js";
+import { verifyDigest } from "../digest-auth.js";
 
 // Inbound device push endpoints. The Dingtian board's "Input Link URL" feature
 // HTTP-calls us when an input (button) fires — no polling. We translate the
 // push into an internal device event; the entry flow decides what to do
-// (print a ticket, then command the relay). See wiki/entities/dingtian-relay.md.
+// (print a ticket, then command the relay). See wiki/concepts/device-input-flow.md.
 //
-// AUTH: these are machine-to-machine calls FROM the device, which can't do the
-// SPA's cookie/CSRF auth. They are intentionally NOT behind requireRole. Trust
-// does NOT come from this request — every barrier open is a host decision
-// recorded as a signed event, so an out-of-band/forged open has no matching
-// signed event and shows up as an anomaly (see wiki/concepts/append-only-event-chain
-// and threat-model). A shared-secret check can be layered on later as
-// defence-in-depth; on a flat network it isn't the security boundary.
+// AUTH: HTTP Digest (the device can do Digest but not HTTPS-to-self-signed —
+// both tested on hardware). The password is never sent on the wire; the secret
+// is NOT in the URL. Per-device credentials live in lane_devices (written on
+// assign). This is defence-in-depth on a flat network; the signed event log is
+// the real anti-fraud guarantee (an open with no matching signed event is an
+// anomaly). Source-IP is also checked. NOT behind the SPA cookie/CSRF auth
+// (machine call from the device).
 
 interface InputParams {
   deviceId: string;
   n: string;
+  edge: string;
 }
 
-export async function deviceRoutes(app: FastifyInstance): Promise<void> {
-  // Dingtian input ON-edge push (button pressed). The device is configured
-  // (via input_link_url) to call this path for each input. GET or POST both
-  // accepted — the device's method is configurable; the URL carries the input.
-  const handler = (edge: "on" | "off") =>
-    async (req: FastifyRequest<{ Params: InputParams }>) => {
-      const { deviceId, n } = req.params;
-      const input = Number(n);
-      app.log.info(`[dingtian:${deviceId}] input ${input} ${edge} (push)`);
-      deviceEvents.emitInput({
-        driverId: "dingtian",
-        deviceId,
-        input,
-        edge,
-        at: new Date().toISOString(),
-        source: "push",
-      });
-      return { ok: true };
-    };
+interface DingtianDeviceConfig {
+  host?: string;
+  pushUser?: string;
+  pushPassword?: string;
+}
+
+function clientIp(req: FastifyRequest): string {
+  return req.ip.replace(/^::ffff:/, "");
+}
+
+export async function deviceRoutes(app: FastifyInstance, db: Db): Promise<void> {
+  const handle = async (req: FastifyRequest<{ Params: InputParams }>, reply: FastifyReply) => {
+    const { deviceId, n, edge } = req.params;
+
+    const row = await db.select().from(laneDevices).where(eq(laneDevices.id, deviceId)).get();
+    const cfg = row?.config as DingtianDeviceConfig | undefined;
+
+    // Unknown device / not a dingtian / no push creds / wrong source IP → 404.
+    if (
+      !row ||
+      row.driverId !== "dingtian" ||
+      !cfg?.pushUser ||
+      !cfg.pushPassword ||
+      !cfg.host ||
+      clientIp(req) !== cfg.host
+    ) {
+      app.log.warn(`rejected device push: device=${deviceId} ip=${clientIp(req)}`);
+      return reply.code(404).send({ error: "not found" });
+    }
+
+    // Digest auth — issues a 401 challenge on first hit; the device retries with
+    // the hashed response (verifyDigest sends the challenge + returns false).
+    if (!verifyDigest(req, reply, { user: cfg.pushUser, password: cfg.pushPassword })) {
+      return; // 401 already sent
+    }
+
+    const input = Number(n);
+    const ed = edge === "off" ? "off" : "on";
+    app.log.info(`[dingtian:${deviceId}] input ${input} ${ed} (push)`);
+    deviceEvents.emitInput({
+      driverId: "dingtian",
+      deviceId,
+      input,
+      edge: ed,
+      at: new Date().toISOString(),
+      source: "push",
+    });
+    return { ok: true };
+  };
 
   for (const method of ["GET", "POST"] as const) {
     app.route({
       method,
-      url: "/api/devices/dingtian/:deviceId/input/:n/on",
-      handler: handler("on"),
-    });
-    app.route({
-      method,
-      url: "/api/devices/dingtian/:deviceId/input/:n/off",
-      handler: handler("off"),
+      url: "/api/devices/dingtian/:deviceId/input/:n/:edge",
+      handler: handle,
     });
   }
 }