From 016aaa665f25c170d067e2f8acf7d719b258f495 Mon Sep 17 00:00:00 2001
From: Dorseuil Nicolas <nicodorseuil@yahoo.fr>
Date: Thu, 1 Feb 2024 21:54:54 +0100
Subject: [PATCH 1/2] fix trailing slash redirect to external domain

---
 .../open-next/src/adapters/routing/matcher.ts | 20 ++++++++++++++-----
 .../tests/appRouter/trailing.test.ts          |  5 +++++
 2 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/packages/open-next/src/adapters/routing/matcher.ts b/packages/open-next/src/adapters/routing/matcher.ts
index d77e47b5b..5982214b3 100644
--- a/packages/open-next/src/adapters/routing/matcher.ts
+++ b/packages/open-next/src/adapters/routing/matcher.ts
@@ -169,11 +169,13 @@ export function handleRewrites<T extends RewriteDefinition>(
   };
 }
 
-export function handleRedirects(
-  event: InternalEvent,
-  redirects: RedirectDefinition[],
-): InternalResult | undefined {
+function handleTrailingSlashRedirect(event: InternalEvent) {
   if (!NextConfig.skipTrailingSlashRedirect) {
+    const url = new URL(event.url, "http://localhost");
+    // Someone is trying to redirect to a different origin, let's not do that
+    if (url.host !== "localhost") {
+      return false;
+    }
     if (
       NextConfig.trailingSlash &&
       !event.headers["x-nextjs-data"] &&
@@ -211,7 +213,15 @@ export function handleRedirects(
         isBase64Encoded: false,
       };
     }
-  }
+  } else return false;
+}
+
+export function handleRedirects(
+  event: InternalEvent,
+  redirects: RedirectDefinition[],
+): InternalResult | undefined {
+  const trailingSlashRedirect = handleTrailingSlashRedirect(event);
+  if (trailingSlashRedirect) return trailingSlashRedirect;
   const { internalEvent, __rewrite } = handleRewrites(
     event,
     redirects.filter((r) => !r.internal),
diff --git a/packages/tests-e2e/tests/appRouter/trailing.test.ts b/packages/tests-e2e/tests/appRouter/trailing.test.ts
index aeffc92ed..a64a22610 100644
--- a/packages/tests-e2e/tests/appRouter/trailing.test.ts
+++ b/packages/tests-e2e/tests/appRouter/trailing.test.ts
@@ -15,3 +15,8 @@ test("trailingSlash redirect with search parameters", async ({ page }) => {
   );
   expect(response?.request().url()).toMatch(/\/ssr\?happy=true$/);
 });
+
+test("trailingSlash redirect to external domain", async ({ page, baseURL }) => {
+  const response = await page.goto(`${baseURL}//sst.dev/`);
+  expect(response?.status()).toBe(404);
+});

From 72766a81b157fafbdff29fe4d616aab09aeefee8 Mon Sep 17 00:00:00 2001
From: conico974 <nicodorseuil@yahoo.fr>
Date: Thu, 1 Feb 2024 23:58:27 +0100
Subject: [PATCH 2/2] changeset

---
 .changeset/tame-hotels-tell.md | 6 ++++++
 1 file changed, 6 insertions(+)
 create mode 100644 .changeset/tame-hotels-tell.md

diff --git a/.changeset/tame-hotels-tell.md b/.changeset/tame-hotels-tell.md
new file mode 100644
index 000000000..b966b6f51
--- /dev/null
+++ b/.changeset/tame-hotels-tell.md
@@ -0,0 +1,6 @@
+---
+"open-next": patch
+"tests-e2e": patch
+---
+
+Fix trailing slash redirect to external domain