feat(feedback): Rate-Limit und Spam-Erkennung für Feedback-Formular

Schützt den Feedback-Endpunkt vor Missbrauch durch pro-Nutzer-Limits, Honeypot, Zeitprüfung und einfache Inhaltsheuristiken.

Co-authored-by: Cursor <cursoragent@cursor.com>

server/src/middleware/feedbackProtection.ts

@@ -0,0 +1,79 @@
+import rateLimit from 'express-rate-limit'
+import type { AuthedRequest } from './auth.js'
+
+const MIN_SUBMIT_MS = 2_000
+const MAX_SUBMIT_MS = 60 * 60 * 1000
+const DUPLICATE_WINDOW_MS = 10 * 60 * 1000
+const MAX_URLS = 8
+const MAX_REPEATED_CHAR = 40
+
+const recentByUser = new Map<string, { hash: string; at: number }>()
+
+function normalizeMessage(message: string): string {
+  return message.trim().toLowerCase().replace(/\s+/g, ' ')
+}
+
+function countUrls(message: string): number {
+  const matches = message.match(/https?:\/\/|www\./gi)
+  return matches?.length ?? 0
+}
+
+function hasExcessiveRepeatedChars(message: string): boolean {
+  return /(.)\1{39,}/.test(message)
+}
+
+function pruneRecentEntries(now: number): void {
+  for (const [userId, entry] of recentByUser) {
+    if (now - entry.at > DUPLICATE_WINDOW_MS) {
+      recentByUser.delete(userId)
+    }
+  }
+}
+
+export type FeedbackSpamVerdict = 'ok' | 'silent_reject' | 'reject'
+
+export function analyzeFeedbackSpam(
+  userId: string,
+  payload: { message: string; website?: unknown; openedAt?: unknown }
+): FeedbackSpamVerdict {
+  if (typeof payload.website === 'string' && payload.website.trim()) {
+    return 'silent_reject'
+  }
+
+  if (typeof payload.openedAt === 'number' && Number.isFinite(payload.openedAt)) {
+    const elapsed = Date.now() - payload.openedAt
+    if (elapsed < MIN_SUBMIT_MS || elapsed > MAX_SUBMIT_MS) {
+      return 'silent_reject'
+    }
+  }
+
+  const normalized = normalizeMessage(payload.message)
+  const now = Date.now()
+  pruneRecentEntries(now)
+
+  const previous = recentByUser.get(userId)
+  if (previous && previous.hash === normalized && now - previous.at < DUPLICATE_WINDOW_MS) {
+    return 'reject'
+  }
+
+  if (countUrls(payload.message) > MAX_URLS || hasExcessiveRepeatedChars(payload.message)) {
+    return 'reject'
+  }
+
+  recentByUser.set(userId, { hash: normalized, at: now })
+  return 'ok'
+}
+
+export const feedbackLimiter = rateLimit({
+  windowMs: 15 * 60 * 1000,
+  max: 5,
+  standardHeaders: true,
+  legacyHeaders: false,
+  keyGenerator: (req) => (req as AuthedRequest).userId ?? req.ip ?? 'unknown',
+  handler: (_req, res) => {
+    res.status(429).json({
+      error: 'Too many feedback submissions. Please try again later.',
+      code: 'RATE_LIMITED'
+    })
+  }
+})

server/src/routes/feedback.ts

@@ -1,6 +1,7 @@
 import { Router } from 'express'
 import { isNtfyConfigured, sendFeedbackViaNtfy } from '../services/ntfyNotify.js'
 import { requireUser } from '../middleware/auth.js'
+import { analyzeFeedbackSpam, feedbackLimiter } from '../middleware/feedbackProtection.js'
 
 const router = Router()
 
@@ -25,14 +26,24 @@ router.get('/status', requireUser, (_req, res) => {
   res.json({ enabled: isNtfyConfigured() })
 })
 
-router.post('/', requireUser, async (req: any, res) => {
+router.post('/', requireUser, feedbackLimiter, async (req: any, res) => {
   try {
     if (!isNtfyConfigured()) {
       return res.status(503).json({ error: 'Feedback is not configured on this server' })
     }
 
-    const { category, message, username, contactEmail, logbookId, logbookTitle, appVersion, pageUrl } =
-      req.body ?? {}
+    const {
+      category,
+      message,
+      username,
+      contactEmail,
+      logbookId,
+      logbookTitle,
+      appVersion,
+      pageUrl,
+      website,
+      openedAt
+    } = req.body ?? {}
 
     if (typeof category !== 'string' || !VALID_CATEGORIES.has(category)) {
       return res.status(400).json({ error: 'Invalid category' })
@@ -55,6 +66,21 @@ router.post('/', requireUser, async (req: any, res) => {
       }
     }
 
+    const spamVerdict = analyzeFeedbackSpam(req.userId, {
+      message: trimmedMessage,
+      website,
+      openedAt
+    })
+    if (spamVerdict === 'silent_reject') {
+      return res.json({ ok: true })
+    }
+    if (spamVerdict === 'reject') {
+      return res.status(400).json({
+        error: 'This feedback could not be sent. Please change your message and try again.',
+        code: 'SPAM_DETECTED'
+      })
+    }
+
     await sendFeedbackViaNtfy({
       category,
       message: trimmedMessage,