add httpStaticMiddleware before serve static files

packages/node_modules/node-red/red.js

@@ -423,6 +423,11 @@ httpsPromise.then(function(startupHttps) {
     // }
     if (settings.httpStatic) {
         let appUseMem = {};
+        let httpStaticMiddleware = (req, res, next) => next()
+        if (typeof settings.httpStaticMiddleware === 'function' || isArray(settings.httpStaticMiddleware)) {
+          httpStaticMiddleware = settings.httpStaticMiddleware
+        }
+    
         for (let si = 0; si < settings.httpStatic.length; si++) {
             const sp = settings.httpStatic[si];
             const filePath = sp.path;
@@ -434,7 +439,7 @@ httpsPromise.then(function(startupHttps) {
             if (settings.httpStaticAuth) {
                 app.use(thisRoot, basicAuthMiddleware(settings.httpStaticAuth.user, settings.httpStaticAuth.pass));
             }
-            app.use(thisRoot, express.static(filePath));
+            app.use(thisRoot, httpStaticMiddleware, express.static(filePath));
         }
     }
 

packages/node_modules/node-red/settings.js

@@ -239,6 +239,18 @@ module.exports = {
      */
     //httpStaticRoot: '/static/',
 
+    /** The following property can be used to add a custom middleware function
+     * in front of all static files. This allows custom authentication to be
+     * applied to all http in nodes, or any other sort of common request processing.
+     * It can be a single function or an array of middleware functions.
+     */
+    // httpStaticMiddleware: [
+    //   require('compression')({ threshold: 0}),
+    //   function(req,res,next) {
+    //     // for example
+    //     next();
+    //   },
+    // ],
 /*******************************************************************************
  * Runtime Settings
  *  - lang