tight

src/server.ts

@@ -8,19 +8,53 @@ import { readFileSync } from "node:fs";
 import { minify } from "uglify-js";
 const app = express();
 
+const allowedSites = new Set(
+  (process.env.ALLOWED_SITES || "")
+    .split(",")
+    .map(s => s.trim().toLowerCase())
+    .filter(Boolean)
+);
+
 const clientJS =
   minify(readFileSync("src/clientAnalytics.js", "utf8")).code;
 
 app.use(bodyParser.json({ limit: "512kb" }));
 app.use(
-  cors()
+  cors({
+    origin: (origin, callback) => {
+      if (!origin) return callback(null, true);
+      try {
+        const host = new URL(origin).hostname.toLowerCase();
+        if (allowedSites.size === 0 || allowedSites.has(host)) {
+          return callback(null, true);
+        }
+        return callback(new Error("Not allowed by CORS"));
+      } catch {
+        return callback(new Error("Invalid Origin"));
+      }
+    },
+    methods: ["GET", "POST", "OPTIONS"],
+    allowedHeaders: ["Content-Type"],
+  })
 );
 
 if (process.env.TRUST_PROXY) {
   app.set("trust proxy", true);
 }
 app.options("*path", (req, res) => {
-  res.set("Access-Control-Allow-Origin", "*");
+  const origin = req.get("Origin") || "";
+  let ok = true;
+  if (allowedSites.size > 0) {
+    try {
+      const host = new URL(origin).hostname.toLowerCase();
+      ok = allowedSites.has(host);
+    } catch {
+      ok = false;
+    }
+  }
+  if (!ok) return res.sendStatus(403);
+  res.set("Vary", "Origin");
+  res.set("Access-Control-Allow-Origin", origin || "*");
   res.set("Access-Control-Allow-Methods", "GET,POST,OPTIONS");
   res.set("Access-Control-Allow-Headers", "Content-Type");
   res.sendStatus(204);
@@ -108,6 +142,10 @@ app.post("/some-cool-endpoint", (req, res) => {
     } catch (err) {
     }
   }
+  site = (site || "").toLowerCase();
+  if (allowedSites.size > 0 && !allowedSites.has(site)) {
+    return res.sendStatus(403);
+  }
 
   eventCounter.labels(site, e.type, country, device, browser, os).inc();
 
@@ -136,9 +174,14 @@ app.get("/js", async (req, res) => {
   const partial_url = req.protocol + "://" + req.get("host");
 
   const url = new URL(partial_url + req.url);
-  const id = url.searchParams.get("site") || url.hostname;
+  const id = (url.searchParams.get("site") || url.hostname || "").toLowerCase();
+  if (allowedSites.size > 0 && !allowedSites.has(id)) {
+    res.status(403).send("site not allowed");
+    return;
+  }
 
   res.set('Content-Type', 'text/javascript')
+  res.set('Vary', 'Origin')
   res.end(clientJS.replace(
     "some_misc_string", partial_url
   ).replace("some_site_string", id)