From ec1b1188d482eb6b519c4340f5ce2c25ecd9f87a Mon Sep 17 00:00:00 2001
From: Lucas Michot <lucas@semalead.com>
Date: Mon, 11 Oct 2021 19:38:00 +0200
Subject: [PATCH] Do not let SetCacheHeaders override the eTag.

---
 src/Illuminate/Http/Middleware/SetCacheHeaders.php | 2 +-
 tests/Http/Middleware/CacheTest.php                | 9 +++++++++
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/src/Illuminate/Http/Middleware/SetCacheHeaders.php b/src/Illuminate/Http/Middleware/SetCacheHeaders.php
index b42dc2f2f822..770a523ae249 100644
--- a/src/Illuminate/Http/Middleware/SetCacheHeaders.php
+++ b/src/Illuminate/Http/Middleware/SetCacheHeaders.php
@@ -30,7 +30,7 @@ public function handle($request, Closure $next, $options = [])
         }
 
         if (isset($options['etag']) && $options['etag'] === true) {
-            $options['etag'] = md5($response->getContent());
+            $options['etag'] = $response->getEtag() ?? md5($response->getContent());
         }
 
         if (isset($options['last_modified'])) {
diff --git a/tests/Http/Middleware/CacheTest.php b/tests/Http/Middleware/CacheTest.php
index 0f75ed79d3a9..20b6579fff86 100644
--- a/tests/Http/Middleware/CacheTest.php
+++ b/tests/Http/Middleware/CacheTest.php
@@ -63,6 +63,15 @@ public function testGenerateEtag()
         $this->assertSame('max-age=100, public, s-maxage=200', $response->headers->get('Cache-Control'));
     }
 
+    public function testDoesNotOverrideEtag()
+    {
+        $response = (new Cache)->handle(new Request, function () {
+            return (new Response('some content'))->setEtag('XYZ');
+        }, 'etag');
+
+        $this->assertSame('"XYZ"', $response->getEtag());
+    }
+
     public function testIsNotModified()
     {
         $request = new Request;