fix: it should handle already encoded parts in the URL when redirecting

__tests__/redirector.ts

@@ -105,6 +105,22 @@ describe('GET /r/:postId', () => {
       .expect(302)
       .expect('Location', 'http://localhost:5002/posts/p1-p1');
   });
+
+  it('should not escape already encoded URL', async () => {
+    await con
+      .getRepository(ArticlePost)
+      .update(
+        { id: 'p1' },
+        { url: 'http://p1.com/hello%20world/%f0%9f%9a%80-to-the-🌔' },
+      );
+    return request(app.server)
+      .get('/r/p1')
+      .expect(302)
+      .expect(
+        'Location',
+        'http://p1.com/hello%20world/%f0%9f%9a%80-to-the-%F0%9F%8C%94?ref=dailydev',
+      );
+  });
 });
 
 describe('GET /:id/profile-image', () => {

src/common/encodeurl.ts

@@ -0,0 +1,52 @@
+/*!
+ * encodeurl
+ * Copyright(c) 2016 Douglas Christopher Wilson
+ * MIT Licensed
+ */
+
+/**
+ * RegExp to match non-URL code points, *after* encoding (i.e. not including "%")
+ * and including invalid escape sequences.
+ * @private
+ */
+
+const ENCODE_CHARS_REGEXP =
+  /(?:[^\x21\x23-\x3B\x3D\x3F-\x5F\x61-\x7A\x7C\x7E]|%(?:[^0-9A-Fa-f]|[0-9A-Fa-f][^0-9A-Fa-f]|$))+/g;
+
+/**
+ * RegExp to match unmatched surrogate pair.
+ * @private
+ */
+
+const UNMATCHED_SURROGATE_PAIR_REGEXP =
+  /(^|[^\uD800-\uDBFF])[\uDC00-\uDFFF]|[\uD800-\uDBFF]([^\uDC00-\uDFFF]|$)/g;
+
+/**
+ * String to replace unmatched surrogate pair with.
+ * @private
+ */
+
+const UNMATCHED_SURROGATE_PAIR_REPLACE = '$1\uFFFD$2';
+
+/**
+ * Encode a URL to a percent-encoded form, excluding already-encoded sequences.
+ *
+ * This function will take an already-encoded URL and encode all the non-URL
+ * code points. This function will not encode the "%" character unless it is
+ * not part of a valid sequence (`%20` will be left as-is, but `%foo` will
+ * be encoded as `%25foo`).
+ *
+ * This encode is meant to be "safe" and does not throw errors. It will try as
+ * hard as it can to properly encode the given URL, including replacing any raw,
+ * unpaired surrogate pairs with the Unicode replacement character prior to
+ * encoding.
+ *
+ * @param {string} url
+ * @return {string}
+ * @public
+ */
+
+export const encodeUrl = (url: string): string =>
+  String(url)
+    .replace(UNMATCHED_SURROGATE_PAIR_REGEXP, UNMATCHED_SURROGATE_PAIR_REPLACE)
+    .replace(ENCODE_CHARS_REGEXP, encodeURI);

src/routes/redirector.ts

@@ -3,6 +3,7 @@ import { FastifyInstance } from 'fastify';
 import { ArticlePost, Post } from '../entity';
 import { getDiscussionLink, notifyView } from '../common';
 import createOrGetConnection from '../db';
+import { encodeUrl } from '../common/encodeurl';
 
 export default async function (fastify: FastifyInstance): Promise<void> {
   fastify.get<{ Params: { postId: string }; Querystring: { a?: string } }>(
@@ -35,7 +36,7 @@ export default async function (fastify: FastifyInstance): Promise<void> {
       }
       const url = new URL(post.url);
       url.searchParams.append('ref', 'dailydev');
-      const encodedUri = encodeURI(url.href);
+      const encodedUri = encodeUrl(url.href);
       if (req.isBot) {
         return res.status(302).redirect(encodedUri);
       }