Feat: refactor routes.js express entrypoint config

Feat: express config script refactor

Feat: add state and settingsCache files

lib/middlewares/filterOldRequests.js

@@ -0,0 +1,27 @@
+const state = require('./state')
+const logger = require('../logger')
+
+const CLOCK_SKEW = 60 * 1000
+const REQUEST_TTL = 3 * 60 * 1000
+const THROTTLE_CLOCK_SKEW = 60 * 1000
+
+function filterOldRequests (req, res, next) {
+  const deviceTime = req.deviceTime
+  const deviceId = req.deviceId
+  const timestamp = Date.now()
+  const delta = timestamp - Date.parse(deviceTime)
+
+  const shouldTrigger = !state.canLogClockSkewMap[deviceId] ||
+    timestamp - state.canLogClockSkewMap[deviceId] >= THROTTLE_CLOCK_SKEW
+
+  if (delta > CLOCK_SKEW && shouldTrigger) {
+    state.canLogClockSkewMap[deviceId] = timestamp
+    logger.error('Clock skew with lamassu-machine[%s] too high [%ss], adjust lamassu-machine clock',
+      req.deviceName, (delta / 1000).toFixed(2))
+  }
+
+  if (delta > REQUEST_TTL) return res.status(408).json({ error: 'stale' })
+  next()
+}
+
+module.exports = filterOldRequests