🛡️ Sentinel: Add dual rate-limiting for auth server actions

.github/workflows/ci.yml

@@ -45,6 +45,8 @@ jobs:
           fetch-depth: 0
 
       - uses: pnpm/action-setup@v6
+        with:
+          version: 11.14.0
 
       - uses: actions/setup-node@v7
         with:
@@ -134,6 +136,8 @@ jobs:
       - uses: actions/checkout@v7
 
       - uses: pnpm/action-setup@v6
+        with:
+          version: 11.14.0
 
       - uses: actions/setup-node@v7
         with:
@@ -196,6 +200,8 @@ jobs:
       - uses: actions/checkout@v7
 
       - uses: pnpm/action-setup@v6
+        with:
+          version: 11.14.0
 
       - uses: actions/setup-node@v7
         with:

.github/workflows/sentry-alert.yml

@@ -27,6 +27,8 @@ jobs:
       - uses: actions/checkout@v7
 
       - uses: pnpm/action-setup@v6
+        with:
+          version: 11.14.0
 
       - uses: actions/setup-node@v7
         with:

package.json

@@ -72,5 +72,5 @@
       "eslint --fix"
     ]
   },
-  "packageManager": "pnpm@11.13.0+sha512.88d94724d8f2e6c186744a5584c6e59ecac869ec7ba15e9cb4cd628e8dc7066820b2481d8ee3b51ea8da323a7378068aa58c556a3720d32b7c20a051d088363a"
+  "packageManager": "pnpm@11.14.0"
 }

src/app/actions/auth.ts

@@ -15,7 +15,7 @@ import {
   getSession,
 } from '@/lib/auth';
 import { logger } from '@/lib/logger';
-import { rateLimit } from '@/lib/rate-limit';
+import { rateLimitDual } from '@/lib/rate-limit';
 import {
   hashClaimToken,
   PLACEHOLDER_PASSWORD_PREFIX,
@@ -32,7 +32,7 @@ import {
 // ---------------------------------------------------------------------------
 
 export const signUpAction = createSafeAction(signUpSchema, async (data) => {
-  const rl = rateLimit(`signup:${data.email.toLowerCase()}`, 5, 60_000);
+  const rl = await rateLimitDual('signup', data.email.toLowerCase());
   if (!rl.allowed) {
     throw new Error(`Too many attempts. Try again in ${rl.retryAfterSeconds}s.`);
   }
@@ -123,9 +123,9 @@ export const signUpAction = createSafeAction(signUpSchema, async (data) => {
 // ---------------------------------------------------------------------------
 
 export const signInAction = createSafeAction(signInSchema, async (data) => {
-  // Rate-limit BEFORE any DB or scrypt work — the sync scrypt verify is
-  // exactly what an attacker would use to burn the event loop.
-  const rl = rateLimit(`signin:${data.email.toLowerCase()}`, 5, 60_000);
+  // Rate-limit BEFORE any DB or scrypt work — dual rate limit checks IP first,
+  // then target email, blunting brute force, account lockout DoS, and loop abuse.
+  const rl = await rateLimitDual('signin', data.email.toLowerCase());
   if (!rl.allowed) {
     throw new Error(`Too many attempts. Try again in ${rl.retryAfterSeconds}s.`);
   }

src/lib/__tests__/rate-limit.test.ts

@@ -0,0 +1,53 @@
+import { describe, it, expect, beforeEach, vi } from 'vitest';
+import { rateLimit, rateLimitDual, resetRateLimits } from '../rate-limit';
+
+// Mock next/headers
+vi.mock('next/headers', () => ({
+  headers: vi.fn().mockResolvedValue({
+    get: (header: string) => {
+      if (header === 'x-forwarded-for') return '192.168.1.100, 10.0.0.1';
+      if (header === 'x-real-ip') return '192.168.1.100';
+      return null;
+    },
+  }),
+}));
+
+describe('rate-limit module', () => {
+  beforeEach(() => {
+    resetRateLimits();
+  });
+
+  describe('rateLimit', () => {
+    it('allows hits up to limit and blocks subsequent hits', () => {
+      for (let i = 0; i < 3; i++) {
+        const res = rateLimit('test-key', 3, 60_000);
+        expect(res.allowed).toBe(true);
+      }
+      const blocked = rateLimit('test-key', 3, 60_000);
+      expect(blocked.allowed).toBe(false);
+      expect(blocked.retryAfterSeconds).toBeGreaterThan(0);
+    });
+  });
+
+  describe('rateLimitDual', () => {
+    it('enforces target rate limit when IP is within bounds', async () => {
+      const email = 'user@example.com';
+      for (let i = 0; i < 5; i++) {
+        const res = await rateLimitDual('signin', email, { limit: 5, ipLimit: 10 });
+        expect(res.allowed).toBe(true);
+      }
+      const blocked = await rateLimitDual('signin', email, { limit: 5, ipLimit: 10 });
+      expect(blocked.allowed).toBe(false);
+    });
+
+    it('enforces IP rate limit prior to target limit', async () => {
+      for (let i = 0; i < 3; i++) {
+        const res = await rateLimitDual('signin', `user${i}@example.com`, { limit: 5, ipLimit: 3 });
+        expect(res.allowed).toBe(true);
+      }
+      // IP limit reached (3 hits from 192.168.1.100)
+      const blockedByIp = await rateLimitDual('signin', 'newuser@example.com', { limit: 5, ipLimit: 3 });
+      expect(blockedByIp.allowed).toBe(false);
+    });
+  });
+});

src/lib/rate-limit.ts

@@ -8,6 +8,7 @@
  */
 
 import 'server-only';
+import { headers } from 'next/headers';
 
 const buckets = new Map<string, number[]>();
 
@@ -17,6 +18,41 @@ export interface RateLimitResult {
   retryAfterSeconds: number;
 }
 
+export interface RateLimitOptions {
+  /** Maximum hits for the target key (default: 5) */
+  limit?: number;
+  /** Maximum hits for the client IP (default: 10) */
+  ipLimit?: number;
+  /** Sliding window duration in ms (default: 60,000 / 1 min) */
+  windowMs?: number;
+}
+
+/**
+ * Resets all rate-limiting buckets. Intended for unit tests.
+ */
+export function resetRateLimits(): void {
+  buckets.clear();
+}
+
+/**
+ * Retrieve client IP address from incoming HTTP headers safely.
+ */
+export async function getClientIp(): Promise<string | null> {
+  try {
+    const reqHeaders = await headers();
+    const xff = reqHeaders.get('x-forwarded-for');
+    if (xff) {
+      const clientIp = xff.split(',')[0]?.trim();
+      if (clientIp) return clientIp;
+    }
+    const realIp = reqHeaders.get('x-real-ip');
+    if (realIp) return realIp.trim();
+  } catch {
+    // headers() throws if called outside request context
+  }
+  return null;
+}
+
 /**
  * Record a hit for `key` and report whether it stays within `limit` hits
  * per `windowMs`. Denied hits are not recorded (a blocked attacker doesn't
@@ -47,3 +83,28 @@ export function rateLimit(key: string, limit = 5, windowMs = 60_000): RateLimitR
 
   return { allowed: true, retryAfterSeconds: 0 };
 }
+
+/**
+ * Dual rate-limiter that checks both client IP and target key (e.g. email).
+ * Crucially, IP limit is evaluated FIRST to prevent an IP-blocked attacker
+ * from consuming or polluting target-based buckets (preventing Account Lockout DoS).
+ */
+export async function rateLimitDual(
+  actionPrefix: string,
+  targetKey: string,
+  options: RateLimitOptions = {},
+): Promise<RateLimitResult> {
+  const windowMs = options.windowMs ?? 60_000;
+  const targetLimit = options.limit ?? 5;
+  const ipLimit = options.ipLimit ?? 10;
+
+  const ip = await getClientIp();
+  if (ip) {
+    const ipRes = rateLimit(`${actionPrefix}:ip:${ip}`, ipLimit, windowMs);
+    if (!ipRes.allowed) {
+      return ipRes;
+    }
+  }
+
+  return rateLimit(`${actionPrefix}:target:${targetKey}`, targetLimit, windowMs);
+}