fix: rsc content-type header not matching with charset (#70033)

`charset` can be included in the `content-type` header which currently causes `RSC` detection to fail when it shouldn't so this relaxes the check to just ensure the RSC `content-type` includes the expected type not an exact match. --------- Co-authored-by: JJ Kasper <jj@jjsweb.site>
vercel · Sep 16, 2024 · 02f886a · 02f886a
1 parent 3842680
commit 02f886a
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Showing 3 changed files with 10 additions and 4 deletions.
diff --git a/packages/next/src/client/components/router-reducer/fetch-server-response.ts b/packages/next/src/client/components/router-reducer/fetch-server-response.ts
@@ -178,7 +178,7 @@ export async function fetchServerResponse(
     const interception = !!res.headers.get('vary')?.includes(NEXT_URL)
     const isPrerender = !!res.headers.get(NEXT_IS_PRERENDER_HEADER)
     const postponed = !!res.headers.get(NEXT_DID_POSTPONE_HEADER)
-    let isFlightResponse = contentType === RSC_CONTENT_TYPE_HEADER
+    let isFlightResponse = contentType.startsWith(RSC_CONTENT_TYPE_HEADER)
 
     if (process.env.NODE_ENV === 'production') {
       if (process.env.__NEXT_CONFIG_OUTPUT === 'export') {

diff --git a/packages/next/src/client/components/router-reducer/reducers/server-action-reducer.ts b/packages/next/src/client/components/router-reducer/reducers/server-action-reducer.ts
@@ -113,7 +113,7 @@ async function fetchServerAction(
 
   const contentType = res.headers.get('content-type')
 
-  if (contentType === RSC_CONTENT_TYPE_HEADER) {
+  if (contentType?.startsWith(RSC_CONTENT_TYPE_HEADER)) {
     const response: ActionFlightResponse = await createFromFetch(
       Promise.resolve(res),
       {

diff --git a/packages/next/src/server/app-render/action-handler.ts b/packages/next/src/server/app-render/action-handler.ts
@@ -218,7 +218,9 @@ async function createForwardedActionResponse(
       },
     })
 
-    if (response.headers.get('content-type') === RSC_CONTENT_TYPE_HEADER) {
+    if (
+      response.headers.get('content-type')?.startsWith(RSC_CONTENT_TYPE_HEADER)
+    ) {
       // copy the headers from the redirect response to the response we're sending
       for (const [key, value] of response.headers) {
         if (!actionsForbiddenHeaders.includes(key)) {
@@ -340,7 +342,11 @@ async function createRedirectRenderResult(
         },
       })
 
-      if (response.headers.get('content-type') === RSC_CONTENT_TYPE_HEADER) {
+      if (
+        response.headers
+          .get('content-type')
+          ?.startsWith(RSC_CONTENT_TYPE_HEADER)
+      ) {
         // copy the headers from the redirect response to the response we're sending
         for (const [key, value] of response.headers) {
           if (!actionsForbiddenHeaders.includes(key)) {