From 4ca9042bcd20787e178e52960eee90dc83a19aef Mon Sep 17 00:00:00 2001
From: Naomi Carrigan <commits@nhcarrigan.com>
Date: Sat, 5 Jul 2025 16:09:36 -0700
Subject: [PATCH] feat: add cache to block IPs from brute force attempts

---
 server/src/cache/blockedIps.ts         |  7 +++++
 server/src/hooks/ips.ts                | 36 ++++++++++++++++++++++++++
 server/src/index.ts                    |  2 ++
 server/src/modules/getIpFromRequest.ts | 25 ++++++++++++++++++
 server/src/routes/announcement.ts      | 10 ++++++-
 5 files changed, 79 insertions(+), 1 deletion(-)
 create mode 100644 server/src/cache/blockedIps.ts
 create mode 100644 server/src/hooks/ips.ts
 create mode 100644 server/src/modules/getIpFromRequest.ts

diff --git a/server/src/cache/blockedIps.ts b/server/src/cache/blockedIps.ts
new file mode 100644
index 0000000..5277359
--- /dev/null
+++ b/server/src/cache/blockedIps.ts
@@ -0,0 +1,7 @@
+/**
+ * @copyright nhcarrigan
+ * @license Naomi's Public License
+ * @author Naomi Carrigan
+ */
+
+export const blockedIps: Array<{ ip: string; ttl: Date }> = [];
diff --git a/server/src/hooks/ips.ts b/server/src/hooks/ips.ts
new file mode 100644
index 0000000..d892adc
--- /dev/null
+++ b/server/src/hooks/ips.ts
@@ -0,0 +1,36 @@
+/**
+ * @copyright nhcarrigan
+ * @license Naomi's Public License
+ * @author Naomi Carrigan
+ */
+
+import { blockedIps } from "../cache/blockedIps.js";
+import { getIpFromRequest } from "../modules/getIpFromRequest.js";
+import type { onRequestHookHandler } from "fastify";
+
+/**
+ * Ensures that form submissions only come from our web application.
+ * @param request - The request payload from the server.
+ * @param response - The reply handler from Fastify.
+ * @returns A Fastify reply if the request is invalid, otherwise undefined.
+ */
+// eslint-disable-next-line @typescript-eslint/no-misused-promises -- For reasons I cannot comprehend, Fastify seems to require us to return a request?
+export const ipHook: onRequestHookHandler = async(request, response) => {
+  const ip = getIpFromRequest(request);
+  const ipRecord = blockedIps.find(
+    (record) => {
+      return record.ip === ip && record.ttl > new Date();
+    },
+  );
+  if (ipRecord && ipRecord.ttl > new Date()) {
+    return await response.
+      status(403).
+      send({
+        error: `Your IP address (${ipRecord.ip}) has been blocked until ${ipRecord.ttl.toISOString()}, to protect our API against brute-force attacks.`,
+      });
+  }
+  if (ipRecord && ipRecord.ttl <= new Date()) {
+    blockedIps.splice(blockedIps.indexOf(ipRecord), 1);
+  }
+  return undefined;
+};
diff --git a/server/src/index.ts b/server/src/index.ts
index 0eee3a0..f85d544 100644
--- a/server/src/index.ts
+++ b/server/src/index.ts
@@ -6,6 +6,7 @@
 
 import fastify from "fastify";
 import { corsHook } from "./hooks/cors.js";
+import { ipHook } from "./hooks/ips.js";
 import { announcementRoutes } from "./routes/announcement.js";
 import { baseRoutes } from "./routes/base.js";
 import { logger } from "./utils/logger.js";
@@ -15,6 +16,7 @@ const server = fastify({
 });
 
 server.addHook("preHandler", corsHook);
+server.addHook("preHandler", ipHook);
 
 server.register(baseRoutes);
 server.register(announcementRoutes);
diff --git a/server/src/modules/getIpFromRequest.ts b/server/src/modules/getIpFromRequest.ts
new file mode 100644
index 0000000..5050dfe
--- /dev/null
+++ b/server/src/modules/getIpFromRequest.ts
@@ -0,0 +1,25 @@
+/**
+ * @copyright nhcarrigan
+ * @license Naomi's Public License
+ * @author Naomi Carrigan
+ */
+
+import type { FastifyRequest } from "fastify";
+
+/**
+ * Parses an IP address from a request, first looking for the
+ * Cloudflare headers, then falling back to the request IP.
+ * @param request - The Fastify request object.
+ * @returns The IP address as a string.
+ */
+export const getIpFromRequest = (request: FastifyRequest): string => {
+  const header
+    = request.headers["X-Forwarded-For"] ?? request.headers["Cf-Connecting-IP"];
+  if (typeof header === "string") {
+    return header;
+  }
+  if (Array.isArray(header)) {
+    return header[0] ?? header.join(", ");
+  }
+  return request.ip;
+};
diff --git a/server/src/routes/announcement.ts b/server/src/routes/announcement.ts
index 1b20680..ac2e98e 100644
--- a/server/src/routes/announcement.ts
+++ b/server/src/routes/announcement.ts
@@ -4,11 +4,15 @@
  * @author Naomi Carrigan
  */
 
+import { blockedIps } from "../cache/blockedIps.js";
 import { database } from "../db/database.js";
 import { announceOnDiscord } from "../modules/announceOnDiscord.js";
 import { announceOnForum } from "../modules/announceOnForum.js";
+import { getIpFromRequest } from "../modules/getIpFromRequest.js";
 import type { FastifyPluginAsync } from "fastify";
 
+const oneDay = 24 * 60 * 60 * 1000;
+
 /**
  * Mounts the entry routes for the application. These routes
  * should not require CORS, as they are used by external services
@@ -34,10 +38,14 @@ export const announcementRoutes: FastifyPluginAsync = async(server) => {
     async(request, reply) => {
       const token = request.headers.authorization;
       if (token === undefined || token !== process.env.ANNOUNCEMENT_TOKEN) {
+        blockedIps.push({
+          ip:  getIpFromRequest(request),
+          ttl: new Date(Date.now() + oneDay),
+        });
         return await reply.status(401).send({
           error:
             // eslint-disable-next-line stylistic/max-len -- Big boi string.
-            "This endpoint requires a special auth token. If you believe you should have access, please contact Naomi.",
+            "This endpoint requires a special auth token. If you believe you should have access, please contact Naomi. To protect our services, your IP has been blocked from all routes for 24 hours.",
         });
       }