From 4965b476c9eb6405932d8e0b51039ac64e983525 Mon Sep 17 00:00:00 2001
From: Ruben Verborgh <ruben@verborgh.org>
Date: Wed, 2 Sep 2020 16:04:36 +0200
Subject: [PATCH] feat: Send server identification

---
 src/server/ExpressHttpServer.ts            | 15 +++++++++++++--
 test/unit/server/ExpressHttpServer.test.ts |  7 +++++++
 2 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/src/server/ExpressHttpServer.ts b/src/server/ExpressHttpServer.ts
index 3658ddf51..e2f64b346 100644
--- a/src/server/ExpressHttpServer.ts
+++ b/src/server/ExpressHttpServer.ts
@@ -1,6 +1,6 @@
 import { Server } from 'http';
 import cors from 'cors';
-import express from 'express';
+import express, { Express } from 'express';
 import { HttpHandler } from './HttpHandler';
 
 export class ExpressHttpServer {
@@ -12,7 +12,18 @@ export class ExpressHttpServer {
 
   public listen(port?: number): Server {
     const app = express();
+    this.setup(app);
+    return app.listen(port);
+  }
 
+  protected setup(app: Express): void {
+    // Set up server identification
+    app.use((request, response, done): void => {
+      response.setHeader('X-Powered-By', 'Community Solid Server');
+      done();
+    });
+
+    // Set up Cross-Origin Resource Sharing (CORS)
     app.use(cors({
       // Based on https://github.com/solid/solid-spec/blob/master/recommendations-server.md#cors---cross-origin-resource-sharing
       // By default origin is always '*', this forces it to be the origin header if there is one
@@ -20,6 +31,7 @@ export class ExpressHttpServer {
       methods: [ 'GET', 'HEAD', 'OPTIONS', 'POST', 'PUT', 'PATCH', 'DELETE' ],
     }));
 
+    // Delegate to the main handler
     app.use(async(request, response, done): Promise<void> => {
       try {
         await this.handler.handleSafe({ request, response });
@@ -31,6 +43,5 @@ export class ExpressHttpServer {
         done();
       }
     });
-    return app.listen(port);
   }
 }
diff --git a/test/unit/server/ExpressHttpServer.test.ts b/test/unit/server/ExpressHttpServer.test.ts
index eeb0ed78b..a33a50a95 100644
--- a/test/unit/server/ExpressHttpServer.test.ts
+++ b/test/unit/server/ExpressHttpServer.test.ts
@@ -42,6 +42,13 @@ describe('ExpressHttpServer', (): void => {
     server.close();
   });
 
+  it('sends server identification in the X-Powered-By header.', async(): Promise<void> => {
+    const res = await request(server).get('/');
+    expect(res.header).toEqual(expect.objectContaining({
+      'x-powered-by': 'Community Solid Server',
+    }));
+  });
+
   it('returns CORS headers for an OPTIONS request.', async(): Promise<void> => {
     const res = await request(server)
       .options('/')