refactor to match Next behavior

Author: sommeeeer

packages/open-next/src/core/routing/util.ts

@@ -1,5 +1,6 @@
 import crypto from "node:crypto";
 import type { OutgoingHttpHeaders } from "node:http";
+import { parse as parseQs, stringify as stringifyQs } from "node:querystring";
 import { Readable } from "node:stream";
 
 import { BuildId, HtmlPages, NextConfig } from "config/index.js";
@@ -442,31 +443,39 @@ export async function invalidateCDNOnRequest(
  * Normalizes the Location header to either be a relative path or a full URL.
  * If the Location header is relative to the origin, it will return a relative path.
  * If it is an absolute URL, it will return the full URL.
- * Both cases will ensure that the Location value is properly encoded according to RFC
+ * Redirects from Next config query parameters are encoded using `stringifyQs`
+ * Redirects from the middleware the query parameters are not encoded.
  *
  * @param location The Location header value
  * @param baseUrl The base URL to use for relative paths (i.e the original request URL)
- * @returns An encoded absolute or relative Location header value
+ * @param encodeQuery Optional flag to indicate if query parameters should be encoded in the Location header
+ * @returns An absolute or relative Location header value
  */
 export function normalizeLocationHeader(
   location: string,
   baseUrl: string,
+  encodeQuery = false,
 ): string {
   if (!URL.canParse(location)) {
     // If the location is not a valid URL, return it as-is
     return location;
   }
 
-  const locationUrl = new URL(location);
+  const locationURL = new URL(location);
   const origin = new URL(baseUrl).origin;
 
-  // Encode the search parameters to ensure they are valid according to RFC
-  const searchParams = locationUrl.searchParams.toString();
-  const encodedSearch = searchParams ? `?${searchParams}` : "";
-  const href = `${locationUrl.origin}${locationUrl.pathname}${encodedSearch}${locationUrl.hash}`;
-
+  // Redirects from the middleware do not encode the query parameters
+  let search = locationURL.search;
+  // If encodeQuery is true, we need to encode the query parameters
+  // This is used for redirects from Next config
+  // We could have used URLSearchParams, but that encodes it too much. stringify from querystring uses encodeURIComponent
+  // which is what Next.js does for redirects from the config
+  if (encodeQuery) {
+    search = search ? `?${stringifyQs(parseQs(search.slice(1)))}` : "";
+  }
+  const href = `${locationURL.origin}${locationURL.pathname}${search}${locationURL.hash}`;
   // The URL is relative if the origin is the same as the base URL's origin
-  if (locationUrl.origin === origin) {
+  if (locationURL.origin === origin) {
     return href.slice(origin.length);
   }
   return href;

packages/open-next/src/core/routingHandler.ts

@@ -109,10 +109,10 @@ export default async function routingHandler(
     const redirect = handleRedirects(eventOrResult, RoutesManifest.redirects);
     if (redirect) {
       // We need to encode the value in the Location header to make sure it is valid according to RFC
-      // https://stackoverflow.com/a/7654605/16587222
       redirect.headers.Location = normalizeLocationHeader(
         redirect.headers.Location as string,
         event.url,
+        true,
       );
       debug("redirect", redirect);
       return redirect;