From 47b0f43fc26ef1545b351bf4289364cad5700a83 Mon Sep 17 00:00:00 2001
From: Steven <steven@ceriously.com>
Date: Mon, 25 Oct 2021 19:56:53 -0400
Subject: [PATCH 1/5] Fix middleware header propegation

---
 packages/next/server/next-server.ts                    | 10 +++++++++-
 .../middleware-core/pages/responses/_middleware.js     |  5 +++++
 .../pages/responses/deep/_middleware.js                | 10 ++++++++++
 .../middleware-core/pages/responses/deep/index.js      | 10 ++++++++++
 test/integration/middleware-core/test/index.test.js    | 10 ++++++++++
 5 files changed, 44 insertions(+), 1 deletion(-)
 create mode 100644 test/integration/middleware-core/pages/responses/deep/_middleware.js
 create mode 100644 test/integration/middleware-core/pages/responses/deep/index.js

diff --git a/packages/next/server/next-server.ts b/packages/next/server/next-server.ts
index 0d9149777e1f863..eeb401de1a870ea 100644
--- a/packages/next/server/next-server.ts
+++ b/packages/next/server/next-server.ts
@@ -624,7 +624,7 @@ export default class Server {
 
     const subreq = params.request.headers[`x-middleware-subrequest`]
     const subrequests = typeof subreq === 'string' ? subreq.split(':') : []
-
+    const allHeaders = new Headers()
     let result: FetchEventResult | null = null
 
     for (const middleware of this.middleware || []) {
@@ -667,6 +667,10 @@ export default class Server {
           },
         })
 
+        for (let [key, value] of result.response.headers) {
+          allHeaders.set(key, value)
+        }
+
         if (!this.renderOpts.dev) {
           result.waitUntil.catch((error) => {
             console.error(`Uncaught: middleware waitUntil errored`, error)
@@ -681,6 +685,10 @@ export default class Server {
 
     if (!result) {
       this.render404(params.request, params.response, params.parsed)
+    } else {
+      for (let [key, value] of allHeaders) {
+        result.response.headers.set(key, value)
+      }
     }
 
     return result
diff --git a/test/integration/middleware-core/pages/responses/_middleware.js b/test/integration/middleware-core/pages/responses/_middleware.js
index 246ab0a18d479af..c1adb758b6f3e74 100644
--- a/test/integration/middleware-core/pages/responses/_middleware.js
+++ b/test/integration/middleware-core/pages/responses/_middleware.js
@@ -15,6 +15,11 @@ export async function middleware(request, ev) {
     next.headers.set('x-nested-header', 'valid')
   }
 
+  // Ensure deep can override top header
+  if (url.searchParams.get('override-me') === 'true') {
+    next.headers.set('x-override-me', 'top')
+  }
+
   // Sends a header
   if (url.pathname === '/responses/header') {
     next.headers.set('x-first-header', 'valid')
diff --git a/test/integration/middleware-core/pages/responses/deep/_middleware.js b/test/integration/middleware-core/pages/responses/deep/_middleware.js
new file mode 100644
index 000000000000000..1f9b62f08522abe
--- /dev/null
+++ b/test/integration/middleware-core/pages/responses/deep/_middleware.js
@@ -0,0 +1,10 @@
+import { NextResponse } from 'next/server'
+
+export async function middleware(request, _event) {
+  const next = NextResponse.next()
+  next.headers.set('x-deep-header', 'valid')
+  if (request.nextUrl.searchParams.get('override-me') === 'true') {
+    next.headers.set('x-override-me', 'deep')
+  }
+  return next
+}
diff --git a/test/integration/middleware-core/pages/responses/deep/index.js b/test/integration/middleware-core/pages/responses/deep/index.js
new file mode 100644
index 000000000000000..5d2341782b7d411
--- /dev/null
+++ b/test/integration/middleware-core/pages/responses/deep/index.js
@@ -0,0 +1,10 @@
+function Deep() {
+  return (
+    <div>
+      <h1>Deep</h1>
+      <p>This is a deep page with deep middleware, check the headers</p>
+    </div>
+  )
+}
+
+export default Deep
diff --git a/test/integration/middleware-core/test/index.test.js b/test/integration/middleware-core/test/index.test.js
index 121375f254f725e..2ba0cd5b22f8078 100644
--- a/test/integration/middleware-core/test/index.test.js
+++ b/test/integration/middleware-core/test/index.test.js
@@ -325,6 +325,16 @@ function responseTests(locale = '') {
     )
     expect(res.headers.get('x-first-header')).toBe('valid')
   })
+
+  it(`${locale} should respond with top level headers and override with deep headers`, async () => {
+    const res = await fetchViaHTTP(
+      context.appPort,
+      `${locale}/responses/deep?nested-header=true&override-me=true`
+    )
+    expect(res.headers.get('x-nested-header')).toBe('valid')
+    expect(res.headers.get('x-deep-header')).toBe('valid')
+    expect(res.headers.get('x-override-me')).toBe('deep')
+  })
 }
 
 function interfaceTests(locale = '') {

From 5a08c013633cefeb0b7fdbd10fd48745925ed6c7 Mon Sep 17 00:00:00 2001
From: Steven <steven@ceriously.com>
Date: Mon, 25 Oct 2021 22:24:13 -0400
Subject: [PATCH 2/5] Fix appending headers

---
 packages/next/server/next-server.ts           |  2 +-
 packages/next/server/web/utils.ts             | 22 +++++++++----------
 .../pages/responses/_middleware.js            |  6 ++---
 .../pages/responses/deep/_middleware.js       |  4 ++--
 .../middleware-core/test/index.test.js        |  4 ++--
 5 files changed, 19 insertions(+), 19 deletions(-)

diff --git a/packages/next/server/next-server.ts b/packages/next/server/next-server.ts
index eeb401de1a870ea..cfe3191d4f50601 100644
--- a/packages/next/server/next-server.ts
+++ b/packages/next/server/next-server.ts
@@ -668,7 +668,7 @@ export default class Server {
         })
 
         for (let [key, value] of result.response.headers) {
-          allHeaders.set(key, value)
+          allHeaders.append(key, value)
         }
 
         if (!this.renderOpts.dev) {
diff --git a/packages/next/server/web/utils.ts b/packages/next/server/web/utils.ts
index 3f2b8cb989403bf..57521b9236a97d4 100644
--- a/packages/next/server/web/utils.ts
+++ b/packages/next/server/web/utils.ts
@@ -20,25 +20,25 @@ export function notImplemented(name: string, method: string): any {
   )
 }
 
-export function fromNodeHeaders(object: NodeHeaders) {
-  const headers: { [k: string]: string } = {}
-  for (let headerKey in object) {
-    const headerValue = object[headerKey]
-    if (Array.isArray(headerValue)) {
-      headers[headerKey] = headerValue.join('; ')
-    } else if (headerValue) {
-      headers[headerKey] = String(headerValue)
+export function fromNodeHeaders(object: NodeHeaders): Headers {
+  const headers = new Headers()
+  for (let [key, value] of Object.entries(object)) {
+    const values = Array.isArray(value) ? value : [value]
+    for (let v of values) {
+      if (v !== undefined) {
+        headers.append(key, v)
+      }
     }
   }
   return headers
 }
 
 export function toNodeHeaders(headers?: Headers): NodeHeaders {
-  const object: NodeHeaders = {}
+  const result: NodeHeaders = {}
   if (headers) {
     for (const [key, value] of headers.entries()) {
-      object[key] = value.includes(';') ? value.split(';') : value
+      result[key] = value
     }
   }
-  return object
+  return result
 }
diff --git a/test/integration/middleware-core/pages/responses/_middleware.js b/test/integration/middleware-core/pages/responses/_middleware.js
index c1adb758b6f3e74..03f31e1c251cc81 100644
--- a/test/integration/middleware-core/pages/responses/_middleware.js
+++ b/test/integration/middleware-core/pages/responses/_middleware.js
@@ -15,9 +15,9 @@ export async function middleware(request, ev) {
     next.headers.set('x-nested-header', 'valid')
   }
 
-  // Ensure deep can override top header
-  if (url.searchParams.get('override-me') === 'true') {
-    next.headers.set('x-override-me', 'top')
+  // Ensure deep can append to this value
+  if (url.searchParams.get('append-me') === 'true') {
+    next.headers.append('x-append-me', 'top')
   }
 
   // Sends a header
diff --git a/test/integration/middleware-core/pages/responses/deep/_middleware.js b/test/integration/middleware-core/pages/responses/deep/_middleware.js
index 1f9b62f08522abe..296476e9035a392 100644
--- a/test/integration/middleware-core/pages/responses/deep/_middleware.js
+++ b/test/integration/middleware-core/pages/responses/deep/_middleware.js
@@ -3,8 +3,8 @@ import { NextResponse } from 'next/server'
 export async function middleware(request, _event) {
   const next = NextResponse.next()
   next.headers.set('x-deep-header', 'valid')
-  if (request.nextUrl.searchParams.get('override-me') === 'true') {
-    next.headers.set('x-override-me', 'deep')
+  if (request.nextUrl.searchParams.get('append-me') === 'true') {
+    next.headers.append('x-append-me', 'deep')
   }
   return next
 }
diff --git a/test/integration/middleware-core/test/index.test.js b/test/integration/middleware-core/test/index.test.js
index 2ba0cd5b22f8078..480f3f94854e4dd 100644
--- a/test/integration/middleware-core/test/index.test.js
+++ b/test/integration/middleware-core/test/index.test.js
@@ -329,11 +329,11 @@ function responseTests(locale = '') {
   it(`${locale} should respond with top level headers and override with deep headers`, async () => {
     const res = await fetchViaHTTP(
       context.appPort,
-      `${locale}/responses/deep?nested-header=true&override-me=true`
+      `${locale}/responses/deep?nested-header=true&append-me=true`
     )
     expect(res.headers.get('x-nested-header')).toBe('valid')
     expect(res.headers.get('x-deep-header')).toBe('valid')
-    expect(res.headers.get('x-override-me')).toBe('deep')
+    expect(res.headers.get('x-append-me')).toBe('top, deep')
   })
 }
 

From d31615b858aa8abe605924b735c32d80c244aaa9 Mon Sep 17 00:00:00 2001
From: Steven <steven@ceriously.com>
Date: Mon, 25 Oct 2021 22:37:47 -0400
Subject: [PATCH 3/5] Special case `Set-Cookie`

---
 packages/next/server/next-server.ts                         | 6 +++++-
 packages/next/server/web/utils.ts                           | 4 ++++
 .../middleware-core/pages/responses/_middleware.js          | 5 +++++
 .../middleware-core/pages/responses/deep/_middleware.js     | 3 +++
 test/integration/middleware-core/test/index.test.js         | 3 ++-
 5 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/packages/next/server/next-server.ts b/packages/next/server/next-server.ts
index cfe3191d4f50601..d9b6b7fb48b049e 100644
--- a/packages/next/server/next-server.ts
+++ b/packages/next/server/next-server.ts
@@ -1164,7 +1164,11 @@ export default class Server {
 
           for (const [key, value] of result.response.headers.entries()) {
             if (key !== 'content-encoding') {
-              res.setHeader(key, value)
+              if (key.toLowerCase() === 'set-cookie') {
+                res.setHeader(key, value.split(', '))
+              } else {
+                res.setHeader(key, value)
+              }
             }
           }
 
diff --git a/packages/next/server/web/utils.ts b/packages/next/server/web/utils.ts
index 57521b9236a97d4..130ad3bc7e21a86 100644
--- a/packages/next/server/web/utils.ts
+++ b/packages/next/server/web/utils.ts
@@ -38,6 +38,10 @@ export function toNodeHeaders(headers?: Headers): NodeHeaders {
   if (headers) {
     for (const [key, value] of headers.entries()) {
       result[key] = value
+      if (key.toLowerCase() === 'set-cookie') {
+        console.log('the value of the cookie header is' + value)
+        result[key] = value.split(', ')
+      }
     }
   }
   return result
diff --git a/test/integration/middleware-core/pages/responses/_middleware.js b/test/integration/middleware-core/pages/responses/_middleware.js
index 03f31e1c251cc81..6329017ec0d6e59 100644
--- a/test/integration/middleware-core/pages/responses/_middleware.js
+++ b/test/integration/middleware-core/pages/responses/_middleware.js
@@ -20,6 +20,11 @@ export async function middleware(request, ev) {
     next.headers.append('x-append-me', 'top')
   }
 
+  // Ensure deep can append to this value
+  if (url.searchParams.get('cookie-me') === 'true') {
+    next.headers.append('set-cookie', 'chocochip')
+  }
+
   // Sends a header
   if (url.pathname === '/responses/header') {
     next.headers.set('x-first-header', 'valid')
diff --git a/test/integration/middleware-core/pages/responses/deep/_middleware.js b/test/integration/middleware-core/pages/responses/deep/_middleware.js
index 296476e9035a392..4d7262838413b75 100644
--- a/test/integration/middleware-core/pages/responses/deep/_middleware.js
+++ b/test/integration/middleware-core/pages/responses/deep/_middleware.js
@@ -6,5 +6,8 @@ export async function middleware(request, _event) {
   if (request.nextUrl.searchParams.get('append-me') === 'true') {
     next.headers.append('x-append-me', 'deep')
   }
+  if (request.nextUrl.searchParams.get('cookie-me') === 'true') {
+    next.headers.append('set-cookie', 'oatmeal')
+  }
   return next
 }
diff --git a/test/integration/middleware-core/test/index.test.js b/test/integration/middleware-core/test/index.test.js
index 480f3f94854e4dd..75ce6db001e67da 100644
--- a/test/integration/middleware-core/test/index.test.js
+++ b/test/integration/middleware-core/test/index.test.js
@@ -329,11 +329,12 @@ function responseTests(locale = '') {
   it(`${locale} should respond with top level headers and override with deep headers`, async () => {
     const res = await fetchViaHTTP(
       context.appPort,
-      `${locale}/responses/deep?nested-header=true&append-me=true`
+      `${locale}/responses/deep?nested-header=true&append-me=true&cookie-me=true`
     )
     expect(res.headers.get('x-nested-header')).toBe('valid')
     expect(res.headers.get('x-deep-header')).toBe('valid')
     expect(res.headers.get('x-append-me')).toBe('top, deep')
+    expect(res.headers.raw()['set-cookie']).toEqual(['chocochip', 'oatmeal'])
   })
 }
 

From 86097d81ba97d10c3e614e099d3dda4cd673d59b Mon Sep 17 00:00:00 2001
From: Steven <steven@ceriously.com>
Date: Mon, 25 Oct 2021 22:46:00 -0400
Subject: [PATCH 4/5] Remove console.log()

---
 packages/next/server/web/utils.ts | 1 -
 1 file changed, 1 deletion(-)

diff --git a/packages/next/server/web/utils.ts b/packages/next/server/web/utils.ts
index 130ad3bc7e21a86..1f789163d66a605 100644
--- a/packages/next/server/web/utils.ts
+++ b/packages/next/server/web/utils.ts
@@ -39,7 +39,6 @@ export function toNodeHeaders(headers?: Headers): NodeHeaders {
     for (const [key, value] of headers.entries()) {
       result[key] = value
       if (key.toLowerCase() === 'set-cookie') {
-        console.log('the value of the cookie header is' + value)
         result[key] = value.split(', ')
       }
     }

From 9d26acadaa21e2dd4d0bdf9805a2c79770d1a8bd Mon Sep 17 00:00:00 2001
From: Steven <steven@ceriously.com>
Date: Mon, 25 Oct 2021 22:50:27 -0400
Subject: [PATCH 5/5] Cleanup tests

---
 .../middleware-core/pages/responses/deep/_middleware.js   | 8 ++------
 test/integration/middleware-core/test/index.test.js       | 2 +-
 2 files changed, 3 insertions(+), 7 deletions(-)

diff --git a/test/integration/middleware-core/pages/responses/deep/_middleware.js b/test/integration/middleware-core/pages/responses/deep/_middleware.js
index 4d7262838413b75..28974fdeb1284e4 100644
--- a/test/integration/middleware-core/pages/responses/deep/_middleware.js
+++ b/test/integration/middleware-core/pages/responses/deep/_middleware.js
@@ -3,11 +3,7 @@ import { NextResponse } from 'next/server'
 export async function middleware(request, _event) {
   const next = NextResponse.next()
   next.headers.set('x-deep-header', 'valid')
-  if (request.nextUrl.searchParams.get('append-me') === 'true') {
-    next.headers.append('x-append-me', 'deep')
-  }
-  if (request.nextUrl.searchParams.get('cookie-me') === 'true') {
-    next.headers.append('set-cookie', 'oatmeal')
-  }
+  next.headers.append('x-append-me', 'deep')
+  next.headers.append('set-cookie', 'oatmeal')
   return next
 }
diff --git a/test/integration/middleware-core/test/index.test.js b/test/integration/middleware-core/test/index.test.js
index 75ce6db001e67da..d359dfa15f50849 100644
--- a/test/integration/middleware-core/test/index.test.js
+++ b/test/integration/middleware-core/test/index.test.js
@@ -326,7 +326,7 @@ function responseTests(locale = '') {
     expect(res.headers.get('x-first-header')).toBe('valid')
   })
 
-  it(`${locale} should respond with top level headers and override with deep headers`, async () => {
+  it(`${locale} should respond with top level headers and append deep headers`, async () => {
     const res = await fetchViaHTTP(
       context.appPort,
       `${locale}/responses/deep?nested-header=true&append-me=true&cookie-me=true`