Allow configuring allowed CORS origins for suggest (#1282)

- Support single-server testing and a local dev server (like Next) that is on a different port from the shields server
- Refactor config schema

With this change, the suggestions work locally in #1273.

doc/self-hosting.md

@@ -139,8 +139,17 @@ If you want to host the frontend on a separate server, such as cloud storage
 or a CDN, you can do that. Just copy the built `index.html` there.
 
 To help out users, you can make the Shields server redirect the server root.
-Set the `FRONTEND_REDIRECT_URL` environment variable:
+Set the `REDIRECT_URI` environment variable:
 
 ```sh
-FRONTEND_REDIRECT_URL=http://my-custom-shields.s3.amazonaws.com/
+REDIRECT_URI=http://my-custom-shields.s3.amazonaws.com/
 ```
+
+If you want to use server suggestions, you should also set `ALLOWED_ORIGIN`:
+
+```sh
+ALLOWED_ORIGIN=http://my-custom-shields.s3.amazonaws.com,https://my-custom-shields.s3.amazonaws.com
+```
+
+This should be a comma-separated list of allowed origin headers. They should
+not have paths or trailing slashes.

lib/server-config.js

@@ -4,25 +4,51 @@
 // should be injected into other components needing it.
 
 const url = require('url');
+const envFlag = require('node-env-flag');
 
-const secureServer = !!process.env.HTTPS;
-const serverPort = +process.env.PORT || +process.argv[2] || (secureServer ? 443 : 80);
-const bindAddress = process.env.BIND_ADDRESS || process.argv[3] || '::';
+function envArray(envVar, defaultValue, delimiter) {
+  delimiter = delimiter || ',';
+  if (envVar) {
+    return envVar.split(delimiter);
+  } else {
+    return defaultValue;
+  }
+}
+
+const isSecure = envFlag(process.env.HTTPS, false);
+const port = +process.env.PORT || +process.argv[2] || (isSecure ? 443 : 80);
+const address = process.env.BIND_ADDRESS || process.argv[3] || '::';
+const baseUri = url.format({
+  protocol: isSecure ? 'https' : 'http',
+  hostname: address,
+  port,
+  pathname: '/',
+});
+
+// The base URI provides a suitable value for development. Production should
+// configure this.
+const allowedOrigin = envArray(process.env.ALLOWED_ORIGIN, baseUri.replace(/\/$/, ''), ',');
 
 const config = {
-  secureServer,
-  secureServerKey: process.env.HTTPS_KEY,
-  secureServerCert: process.env.HTTPS_CRT,
-  serverPort,
-  bindAddress,
-  githubApiUrl: process.env.GITHUB_URL || 'https://api.github.com',
-  frontendUri: url.format({
-    protocol: secureServer ? 'https' : 'http',
-    hostname: bindAddress,
-    port: serverPort,
-    pathname: '/',
-  }),
-  frontendRedirectUrl: process.env.FRONTEND_REDIRECT_URL || process.env.INFOSITE,
+  bind: {
+    port,
+    address,
+  },
+  ssl: {
+    isSecure,
+    key: process.env.HTTPS_KEY,
+    cert: process.env.HTTPS_CRT,
+  },
+  baseUri,
+  redirectUri: process.env.REDIRECT_URI || process.env.INFOSITE,
+  cors: {
+    allowedOrigin,
+  },
+  services: {
+    github: {
+      baseUri: process.env.GITHUB_URL || 'https://api.github.com',
+    },
+  },
 };
 
 module.exports = config;

lib/suggest.js

@@ -12,15 +12,20 @@ const githubApiUrl = process.env.GITHUB_URL || 'https://api.github.com';
 //    - link: target as a string URL.
 //    - badge: shields image URL.
 //    - name: string
-function suggest (data, end, ask) {
-  const origin = ask.req.headers['origin'];
-  if (/^https?:\/\/shields\.io$/.test(origin)) {
-    ask.res.setHeader('Access-Control-Allow-Origin', origin);
-  } else {
-    ask.res.setHeader('Access-Control-Allow-Origin', 'null');
-    end({err: 'Disallowed'});
-    return;
+function suggest (allowedOrigin, data, end, ask) {
+  // Same-host requests may be made in development or in single-server
+  // testing. These are legitimate, but do not have an origin header.
+  const origin = ask.req.headers.origin;
+  if (origin) {
+    if (allowedOrigin.includes(origin)) {
+      ask.res.setHeader('Access-Control-Allow-Origin', origin);
+    } else {
+      ask.res.setHeader('Access-Control-Allow-Origin', 'null');
+      end({err: 'Disallowed'});
+      return;
+    }
   }
+
   let url;
   try {
     url = nodeUrl.parse(data.url);
@@ -122,8 +127,10 @@ function githubLicense (user, repo) {
   });
 }
 
-function setRoutes (camp) {
-  camp.ajax.on('suggest/v1', suggest);
+function setRoutes (allowedOrigin, camp) {
+  camp.ajax.on(
+    'suggest/v1',
+    (data, end, ask) => suggest(allowedOrigin, data, end, ask));
 }
 
 module.exports = {

server.js

@@ -95,15 +95,15 @@ const {
 } = require('./lib/github-provider');
 
 const serverStartTime = new Date((new Date()).toGMTString());
-const { githubApiUrl } = config;
+const githubApiUrl = config.services.github.baseUri;
 
 const camp = require('camp').start({
   documentRoot: path.join(__dirname, 'public'),
-  port: config.serverPort,
-  hostname: config.bindAddress,
-  secure: config.secureServer,
-  cert: config.secureServerCert,
-  key: config.secureServerKey,
+  port: config.bind.port,
+  hostname: config.bind.address,
+  secure: config.ssl.isSecure,
+  cert: config.ssl.cert,
+  key: config.ssl.key,
 });
 
 function reset() {
@@ -123,8 +123,7 @@ module.exports = {
   stop
 };
 
-log('Server is starting up');
-log(config.frontendUri);
+log(`Server is starting up: ${config.baseUri}`);
 
 analytics.load();
 analytics.scheduleAutosaving();
@@ -135,7 +134,7 @@ if (serverSecrets && serverSecrets.gh_client_id) {
   githubAuth.setRoutes(camp);
 }
 
-suggest.setRoutes(camp);
+suggest.setRoutes(config.cors.allowedOrigin, camp);
 
 camp.notfound(/\.(svg|png|gif|jpg|json)/, function(query, match, end, request) {
     var format = match[1];
@@ -7518,10 +7517,10 @@ function(data, match, end, ask) {
   }
 });
 
-if (config.frontendRedirectUrl) {
+if (config.redirectUri) {
   camp.route(/^\/$/, (data, match, end, ask) => {
     ask.res.statusCode = 302;
-    ask.res.setHeader('Location', config.frontendRedirectUrl);
+    ask.res.setHeader('Location', config.redirectUri);
     ask.res.end();
   });
 }