tesla-roadtrip/server/routes/owner.ts

import { Router } from 'express';
import crypto from 'node:crypto';
import { env } from '../config/env.js';
import { createLogger } from '../lib/logger.js';
import {
  clearOwnerCookie,
  isOwnerAuthenticated,
  setOwnerCookie,
  verifyOwnerSecret,
} from '../lib/ownerAuth.js';

const log = createLogger('owner');
const router = Router();

// ─── Device pair-code store (in-memory) ─────────────────────────────────────
// 6-digit short codes minted by an already-logged-in owner session so a
// touchscreen device (the Tesla in-car browser) can log in without retyping
// the long OWNER_SECRET.
//
// Defence in depth — 6 digits is only ~20 bits of entropy on its own:
//   - single-use (delete on success)
//   - 5-minute TTL
//   - per-code failure cap: a code self-destructs after 5 wrong guesses
//   - per-IP rate limit (req.ip via 'trust proxy' = 1, not spoofable)
//   - global rate limit across all IPs (defeats parallel-IP brute force)
const PAIR_CODE_TTL_MS = 5 * 60 * 1000;
const MAX_FAILED_PER_CODE = 5;
const MAX_REDEEM_PER_IP_PER_MIN = 8;
const MAX_REDEEM_GLOBAL_PER_MIN = 30;

interface PairCodeEntry { expiresAt: number; failures: number }
const pairCodes = new Map<string, PairCodeEntry>();
const redeemAttemptsByIp = new Map<string, number[]>();
let redeemAttemptsGlobal: number[] = [];

function cleanPairCodes(): void {
  const now = Date.now();
  for (const [k, v] of pairCodes) if (v.expiresAt < now) pairCodes.delete(k);
}

function recordAttempt(ip: string): { ipLimited: boolean; globalLimited: boolean } {
  const now = Date.now();
  const ipArr = (redeemAttemptsByIp.get(ip) || []).filter(t => now - t < 60_000);
  ipArr.push(now);
  redeemAttemptsByIp.set(ip, ipArr);
  redeemAttemptsGlobal = redeemAttemptsGlobal.filter(t => now - t < 60_000);
  redeemAttemptsGlobal.push(now);
  return {
    ipLimited: ipArr.length > MAX_REDEEM_PER_IP_PER_MIN,
    globalLimited: redeemAttemptsGlobal.length > MAX_REDEEM_GLOBAL_PER_MIN,
  };
}

router.get('/api/auth/owner/status', (req, res) => {
  res.json({
    authenticated: isOwnerAuthenticated(req),
    required: !!env.ownerSecret,
  });
});

router.post('/api/auth/owner', (req, res) => {
  if (!env.ownerSecret) {
    res.status(503).json({ ok: false, reason: 'owner_auth_not_configured' });
    return;
  }
  const { secret } = (req.body || {}) as { secret?: unknown };
  if (!verifyOwnerSecret(secret)) {
    res.status(401).json({ ok: false, reason: 'invalid_secret' });
    return;
  }
  setOwnerCookie(res);
  res.json({ ok: true });
});

router.post('/api/auth/owner/logout', (_req, res) => {
  clearOwnerCookie(res);
  res.json({ ok: true });
});

// ─── Pair code: mint one (requires owner session) ──────────────────────────
router.post('/api/auth/owner/pair-code', (req, res) => {
  if (!isOwnerAuthenticated(req)) {
    res.status(401).json({ ok: false, reason: 'auth_required' });
    return;
  }
  cleanPairCodes();
  // Cap concurrent codes per host to a sane number.
  if (pairCodes.size > 32) {
    res.status(429).json({ ok: false, reason: 'too_many_codes' });
    return;
  }
  let code: string;
  do {
    code = String(crypto.randomInt(100_000, 1_000_000));
  } while (pairCodes.has(code));
  pairCodes.set(code, { expiresAt: Date.now() + PAIR_CODE_TTL_MS, failures: 0 });
  res.json({ ok: true, code, expiresInS: Math.floor(PAIR_CODE_TTL_MS / 1000) });
});

// Mark a failed redeem against every currently-active code. With 6-digit
// entropy, an attacker brute-forcing the keyspace doesn't know which code
// the owner minted — but every wrong guess they make burns life from the
// real code. Five misses during a code's TTL is enough to invalidate it
// and force the owner to re-mint, which defeats parallel-IP brute force.
function markFailureAgainstActiveCodes(): void {
  for (const [code, entry] of pairCodes) {
    entry.failures += 1;
    if (entry.failures > MAX_FAILED_PER_CODE) {
      pairCodes.delete(code);
    }
  }
}

// ─── Pair code: redeem on a new device ──────────────────────────────────────
router.post('/api/auth/owner/pair-redeem', (req, res) => {
  // req.ip is trustworthy because we set 'trust proxy' = 1 in server/index.ts.
  // Do NOT fall back to the X-Forwarded-For header — it's client-controlled.
  const ip = req.ip || 'unknown';
  const { ipLimited, globalLimited } = recordAttempt(ip);
  if (ipLimited || globalLimited) {
    log.warn({ ip, ipLimited, globalLimited }, 'pair-redeem rate limited');
    res.status(429).json({ ok: false, reason: 'rate_limited' });
    return;
  }
  const { code } = (req.body || {}) as { code?: unknown };
  if (typeof code !== 'string' || !/^\d{6}$/.test(code)) {
    markFailureAgainstActiveCodes();
    res.status(400).json({ ok: false, reason: 'bad_code' });
    return;
  }
  cleanPairCodes();
  const entry = pairCodes.get(code);
  if (!entry) {
    markFailureAgainstActiveCodes();
    res.status(401).json({ ok: false, reason: 'invalid_or_expired' });
    return;
  }
  // Success: consume the code, set the cookie.
  pairCodes.delete(code);
  setOwnerCookie(res);
  log.info({ ip }, 'Device paired via owner pair code');
  res.json({ ok: true });
});

export default router;