fix(fetch): properly redirect non-ascii location header url

lib/web/fetch/util.js

@@ -44,7 +44,8 @@ function responseLocationURL (response, requestFragment) {
   // 3. If location is a header value, then set location to the result of
   //    parsing location with response’s URL.
   if (location !== null && isValidHeaderValue(location)) {
-    location = new URL(location, responseURL(response))
+    // Make sure location is properly encoded.
+    location = new URL(Buffer.from(location, 'ascii').toString('utf8'), responseURL(response))
   }
 
   // 4. If location is a URL whose fragment is null, then set location’s

test/fetch/fetch-url-after-redirect.js

@@ -38,3 +38,53 @@ test('after redirecting the url of the response is set to the target url', async
 
   assert.strictEqual(response.url, `http://127.0.0.1:${port}/target`)
 })
+
+test('location header with non-ASCII character redirects to a properly encoded url', async (t) => {
+  /**
+   * @example
+   * ```ts
+   * const server = createServer((req, res) => {
+   *   // redirect -> %EC%95%88%EB%85%95 (안녕), not %C3%AC%C2%95%C2%88%C3%AB%C2%85%C2%95
+   *   if (res.req.url.endsWith('/redirect')) {
+   *     const path = String.fromCharCode.apply(
+   *       null,
+   *       encodeURIComponent('안녕')
+   *         .split('%')
+   *         .slice(1)
+   *         .map(n => parseInt(n, 16))
+   *     )
+   *     res.writeHead(302, {
+   *       Location: `/${path}`
+   *     })
+   *     return res.end()
+   *   }
+   * })
+   * ```
+   */
+  const encodedPath = encodeURIComponent('안녕')
+  const nonEncodedPath = String.fromCharCode.apply(
+    null,
+    encodeURIComponent('안녕')
+      .split('%')
+      .slice(1)
+      .map(n => parseInt(n, 16))
+  )
+
+  const server = createServer((req, res) => {
+    if (res.req.url.endsWith('/redirect')) {
+      res.writeHead(302, undefined, { Location: `/${nonEncodedPath}` })
+      res.end()
+    } else {
+      res.writeHead(200, 'dummy', { 'Content-Type': 'text/plain' })
+      res.end()
+    }
+  })
+  t.after(closeServerAsPromise(server))
+
+  const listenAsync = promisify(server.listen.bind(server))
+  await listenAsync(0)
+  const { port } = server.address()
+  const response = await fetch(`http://127.0.0.1:${port}/redirect`)
+
+  assert.strictEqual(response.url, `http://127.0.0.1:${port}/${encodedPath}`)
+})