fix(auth): add account+IP brute-force rate limiting

middleware/authRateLimiter.js

@@ -0,0 +1,116 @@
+const crypto = require('crypto');
+const { client_logger } = require('../utils/analyticsLogger');
+
+const AUTH_ATTEMPT_WINDOW_MS = Math.max(60 * 1000, parseInt(process.env.AUTH_ATTEMPT_WINDOW_MS || `${15 * 60 * 1000}`, 10));
+const AUTH_ATTEMPT_MAX = Math.max(1, parseInt(process.env.AUTH_ATTEMPT_MAX || '5', 10));
+const AUTH_BLOCK_BASE_MS = Math.max(30 * 1000, parseInt(process.env.AUTH_BLOCK_BASE_MS || `${5 * 60 * 1000}`, 10));
+const AUTH_BLOCK_MAX_MS = Math.max(AUTH_BLOCK_BASE_MS, parseInt(process.env.AUTH_BLOCK_MAX_MS || `${60 * 60 * 1000}`, 10));
+
+const limiterStore = new Map();
+let lastPruneAt = 0;
+
+const getClientIp = (req) => {
+    const forwarded = req.headers['x-forwarded-for']?.split(',')[0]?.trim();
+    const rawIp = forwarded || req.ip || req.connection?.remoteAddress || 'unknown';
+    return rawIp.replace('::ffff:', '');
+};
+
+const hashValue = (value) =>
+    crypto.createHash('sha256').update(String(value)).digest('hex').slice(0, 16);
+
+const getIdentity = (req, mode) => {
+    if (mode === 'token') {
+        const token = (req.body?.token || '').trim();
+        return token ? `token:${hashValue(token)}` : 'token:anonymous';
+    }
+    const username = (req.body?.username || req.body?.email || '').trim().toLowerCase();
+    return username ? `acct:${hashValue(username)}` : 'acct:anonymous';
+};
+
+const getLimiterKey = (req, mode) => `${mode}:${getIdentity(req, mode)}:ip:${getClientIp(req)}`;
+
+const getOrInitRecord = (key, now) => {
+    const existing = limiterStore.get(key);
+    if (existing) {
+        return existing;
+    }
+    const record = {
+        count: 0,
+        windowStartedAt: now,
+        blockedUntil: 0,
+        blockLevel: 0,
+    };
+    limiterStore.set(key, record);
+    return record;
+};
+
+const computeBlockMs = (blockLevel) =>
+    Math.min(AUTH_BLOCK_BASE_MS * (2 ** Math.max(0, blockLevel - 1)), AUTH_BLOCK_MAX_MS);
+
+const authRateLimiter = (mode) => (req, res, next) => {
+    const now = Date.now();
+    if (now - lastPruneAt > 5 * 60 * 1000) {
+        for (const [storeKey, storeValue] of limiterStore.entries()) {
+            const isWindowExpired = now - storeValue.windowStartedAt > AUTH_ATTEMPT_WINDOW_MS;
+            const isNotBlocked = storeValue.blockedUntil <= now;
+            if (isWindowExpired && isNotBlocked) {
+                limiterStore.delete(storeKey);
+            }
+        }
+        lastPruneAt = now;
+    }
+    const key = getLimiterKey(req, mode);
+    const record = getOrInitRecord(key, now);
+
+    if (now - record.windowStartedAt > AUTH_ATTEMPT_WINDOW_MS) {
+        record.count = 0;
+        record.windowStartedAt = now;
+    }
+
+    if (record.blockedUntil > now) {
+        const retryAfterSec = Math.ceil((record.blockedUntil - now) / 1000);
+        res.set('Retry-After', retryAfterSec.toString());
+        client_logger.capture({
+            distinctId: 'app_level',
+            event: 'security@auth@rate_limited',
+            properties: {
+                route: req.originalUrl,
+                method: req.method,
+                mode,
+                keyHash: hashValue(key),
+                retryAfterSec,
+                blockLevel: record.blockLevel,
+            }
+        });
+        return res.status(429).json({ status: 'Too many attempts. Please try again later.' });
+    }
+
+    record.count += 1;
+    if (record.count > AUTH_ATTEMPT_MAX) {
+        record.blockLevel += 1;
+        const blockMs = computeBlockMs(record.blockLevel);
+        record.blockedUntil = now + blockMs;
+        record.count = 0;
+        record.windowStartedAt = now;
+        res.set('Retry-After', Math.ceil(blockMs / 1000).toString());
+        client_logger.capture({
+            distinctId: 'app_level',
+            event: 'security@auth@rate_limited',
+            properties: {
+                route: req.originalUrl,
+                method: req.method,
+                mode,
+                keyHash: hashValue(key),
+                retryAfterSec: Math.ceil(blockMs / 1000),
+                blockLevel: record.blockLevel,
+            }
+        });
+        return res.status(429).json({ status: 'Too many attempts. Please try again later.' });
+    }
+
+    return next();
+};
+
+module.exports = {
+    authRateLimiter,
+};