From 42f91cf01eb40777010d3226366c62db6b990847 Mon Sep 17 00:00:00 2001
From: Juan Pablo Garcia Ripa <sarabadu@gmail.com>
Date: Tue, 5 Oct 2021 23:58:45 +0200
Subject: [PATCH] add glob option to cors origin config

Signed-off-by: Juan Pablo Garcia Ripa <sarabadu@gmail.com>
---
 packages/backend-common/package.json          |  2 ++
 .../src/service/lib/config.test.ts            | 34 ++++++++++++++++++-
 .../backend-common/src/service/lib/config.ts  | 20 ++++++++++-
 yarn.lock                                     |  7 ++++
 4 files changed, 61 insertions(+), 2 deletions(-)

diff --git a/packages/backend-common/package.json b/packages/backend-common/package.json
index 29018ef8c8..3c426d780a 100644
--- a/packages/backend-common/package.json
+++ b/packages/backend-common/package.json
@@ -57,6 +57,7 @@
     "knex": "^0.95.1",
     "lodash": "^4.17.21",
     "logform": "^2.1.1",
+    "micromatch": "^4.0.4",
     "minimatch": "^3.0.4",
     "minimist": "^1.2.5",
     "morgan": "^1.10.0",
@@ -84,6 +85,7 @@
     "@types/concat-stream": "^1.6.0",
     "@types/fs-extra": "^9.0.3",
     "@types/http-errors": "^1.6.3",
+    "@types/micromatch": "^4.0.2",
     "@types/minimist": "^1.2.0",
     "@types/mock-fs": "^4.13.0",
     "@types/morgan": "^1.9.0",
diff --git a/packages/backend-common/src/service/lib/config.test.ts b/packages/backend-common/src/service/lib/config.test.ts
index f2f0c88cfb..10c2d705ca 100644
--- a/packages/backend-common/src/service/lib/config.test.ts
+++ b/packages/backend-common/src/service/lib/config.test.ts
@@ -15,7 +15,7 @@
  */
 
 import { ConfigReader } from '@backstage/config';
-import { readCspOptions } from './config';
+import { readCorsOptions, readCspOptions } from './config';
 
 describe('config', () => {
   describe('readCspOptions', () => {
@@ -42,4 +42,36 @@ describe('config', () => {
       expect(() => readCspOptions(config)).toThrow(/wanted string-array/);
     });
   });
+
+  describe('readCorsOptions', () => {
+    it('reads single string', () => {
+      const config = new ConfigReader({ cors: { origin: 'https://*.value*' } });
+      const cors = readCorsOptions(config);
+      expect(cors).toEqual(
+        expect.objectContaining({
+          origin: expect.any(RegExp),
+        }),
+      );
+
+      const origin = cors?.origin as RegExp;
+      expect(origin.test('https://a.value')).toBe(true);
+      expect(origin.test('http://a.value')).toBe(false);
+    });
+
+    it('reads string array', () => {
+      const config = new ConfigReader({
+        cors: { origin: ['https://*.value*', 'http(s|)://*.value*'] },
+      });
+      const cors = readCorsOptions(config);
+      expect(cors).toEqual(
+        expect.objectContaining({
+          origin: expect.any(Array),
+        }),
+      );
+      const origin = cors?.origin as RegExp[];
+      expect(origin[0].test('https://a.value')).toBe(true);
+      expect(origin[1].test('https://a.value')).toBe(true);
+      expect(origin[1].test('http://a.value')).toBe(true);
+    });
+  });
 });
diff --git a/packages/backend-common/src/service/lib/config.ts b/packages/backend-common/src/service/lib/config.ts
index 77ef925403..5d46e2fccf 100644
--- a/packages/backend-common/src/service/lib/config.ts
+++ b/packages/backend-common/src/service/lib/config.ts
@@ -16,6 +16,7 @@
 
 import { Config } from '@backstage/config';
 import { CorsOptions } from 'cors';
+import { makeRe } from 'micromatch';
 
 export type BaseOptions = {
   listenPort?: string | number;
@@ -112,7 +113,7 @@ export function readCorsOptions(config: Config): CorsOptions | undefined {
   }
 
   return removeUnknown({
-    origin: getOptionalStringOrStrings(cc, 'origin'),
+    origin: getOptionalGlobOrGlobs(cc, 'origin'),
     methods: getOptionalStringOrStrings(cc, 'methods'),
     allowedHeaders: getOptionalStringOrStrings(cc, 'allowedHeaders'),
     exposedHeaders: getOptionalStringOrStrings(cc, 'exposedHeaders'),
@@ -217,6 +218,23 @@ function getOptionalStringOrStrings(
   throw new Error(`Expected string or array of strings, got ${typeof value}`);
 }
 
+function getOptionalGlobOrGlobs(
+  config: Config,
+  key: string,
+): RegExp | RegExp[] | undefined {
+  const value = config.getOptional(key);
+  if (value === undefined) {
+    return value;
+  }
+  if (typeof value === 'string') {
+    return makeRe(value, { debug: true });
+  }
+  if (isStringArray(value)) {
+    return value.map(val => makeRe(val));
+  }
+  throw new Error(`Expected string or array of strings, got ${typeof value}`);
+}
+
 function isStringArray(value: any): value is string[] {
   if (!Array.isArray(value)) {
     return false;
diff --git a/yarn.lock b/yarn.lock
index c961b6045b..ca1483daf5 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -7088,6 +7088,13 @@
   dependencies:
     "@types/braces" "*"
 
+"@types/micromatch@^4.0.2":
+  version "4.0.2"
+  resolved "https://registry.npmjs.org/@types/micromatch/-/micromatch-4.0.2.tgz#ce29c8b166a73bf980a5727b1e4a4d099965151d"
+  integrity sha512-oqXqVb0ci19GtH0vOA/U2TmHTcRY9kuZl4mqUxe0QmJAlIW13kzhuK5pi1i9+ngav8FjpSb9FVS/GE00GLX1VA==
+  dependencies:
+    "@types/braces" "*"
+
 "@types/mime-types@^2.1.0":
   version "2.1.0"
   resolved "https://registry.npmjs.org/@types/mime-types/-/mime-types-2.1.0.tgz#9ca52cda363f699c69466c2a6ccdaad913ea7a73"