moves whitelist to config and catches errors

cli/defaults/siteConfig.json

@@ -18,7 +18,8 @@
     "host": "https://www.example.com",
     "description": "A decentralized hosting platform built on LBRY",
     "twitter": false,
-    "blockListEndpoint": "https://api.lbry.com/file/list_blocked"
+    "blockListEndpoint": "https://api.lbry.com/file/list_blocked",
+    "corsWhitelist": []
   },
   "publishing": {
     "primaryClaimAddress": null,

server/index.js

@@ -24,7 +24,7 @@ const processTrending = require('./utils/processTrending');
 const { setRouteDataInContextMiddleware } = require('./middleware/httpContextMiddleware');
 
 const {
-  details: { port: PORT, blockListEndpoint },
+  details: { port: PORT, blockListEndpoint, corsWhitelist, host },
   startup: { performChecks, performUpdates },
 } = require('@config/siteConfig');
 
@@ -83,23 +83,36 @@ function Server() {
 
     // set HTTP headers to protect against well-known web vulnerabilties
     app.use(helmet());
-    // open cors for lbry.tv lbry.tech localhost lbry.com
-    var whitelist = [
-      'https://lbry.com',
-      'https://lbry.tech',
-      'https://lbry.tv',
-      'http://localhost',
-      'http://localhost:1337',
+    // open cors for site/config:host (current instance)
+    var originWhitelist = [
+      host
     ];
-    var corsOptions = {
+    // whitelist is found in site/config:details:
+    // enter corsWhitelist: ["*"] to allow all
+    // enter your domains otherwise:["https://example.com", ...]
+    if ( corsWhitelist && corsWhitelist.length ) {
+      originWhitelist = originWhitelist.concat(corsWhitelist);
+    }
+
+    var corsOptions = originWhitelist && originWhitelist.includes('*')
+    ? {
+      "origin": "*",
+      "methods": "GET,HEAD,PUT,PATCH,POST,DELETE",
+      "preflightContinue": false,
+      "optionsSuccessStatus": 204
+    }
+    : {
       origin: function(origin, callback) {
-        if (whitelist.indexOf(origin) !== -1) {
+        if ((origin === undefined) || originWhitelist.indexOf(origin) !== -1) {
           callback(null, true);
         } else {
-          callback(new Error('Not allowed by CORS'));
+          let error = new Error(`CORS has blocked this website from access. Contact an administrator from ${host} if you feel this is in error.`);
+          error.code = "ECORS"
+          callback(error);
         }
       },
     };
+
     app.use(cors(corsOptions));
     // Support per-request http-context
     app.use(httpContext.middleware);
@@ -166,6 +179,16 @@ function Server() {
       );
     });
 
+    app.use( (error, req, res, next) => {
+      if (error.code === 'ECORS'){
+        res.status(403);
+        res.send({message: error})
+      } else {
+        res.status(520);
+        res.send({ message: error });
+      }
+    })
+
     this.app = app;
   };
   this.createServer = () => {