From 8f1c9a2c4a6ee5ceb1de405437eb8d559ea15ac6 Mon Sep 17 00:00:00 2001
From: Michael Harrington <kibiz0r@gmail.com>
Date: Tue, 16 Jul 2024 12:11:38 -0400
Subject: [PATCH 1/3] test: added test expecting request headers to get
 lowercased

---
 __tests__/integration.js | 36 +++++++++++++++++++++++++++++++++++-
 1 file changed, 35 insertions(+), 1 deletion(-)

diff --git a/__tests__/integration.js b/__tests__/integration.js
index f1c09a99..2e6ee91d 100644
--- a/__tests__/integration.js
+++ b/__tests__/integration.js
@@ -103,6 +103,40 @@ describe.each(EACH_MATRIX)('%s:%s: integration tests', (eventSourceName, framewo
     expect(response).toEqual(expectedResponse)
   })
 
+  test('headers get lowercased', async () => {
+    app = express()
+    router = express.Router()
+    app.use('/', router)
+    serverlessExpressInstance = serverlessExpress({ app })
+    router.get('/foo', (req, res) => {
+      const xHeaders = Object.fromEntries(
+        Object.entries(req.headers).filter(([name]) => name.startsWith('x-header-'))
+      )
+      res.json({ xHeaders })
+    })
+    const event = makeEvent({
+      eventSourceName: 'apiGatewayV1',
+      path: '/foo',
+      httpMethod: 'GET',
+      multiValueHeaders: undefined,
+      headers: {
+        'X-Header-One': 'Value1',
+        'x-header-two': 'Value2'
+      }
+    })
+    const response = await serverlessExpressInstance(event)
+    const expectedResponse = makeResponse({
+      eventSourceName: 'apiGatewayV1',
+      body: JSON.stringify({
+        xHeaders: {
+          'x-header-one': 'Value1',
+          'x-header-two': 'Value2'
+        }
+      })
+    })
+    expect(response).toMatchObject(expectedResponse)
+  })
+
   test('resolutionMode = CALLBACK', (done) => {
     const jsonResponse = { data: { name: 'Brett' } }
     router.get('/users', (req, res) => {
@@ -287,7 +321,7 @@ describe.each(EACH_MATRIX)('%s:%s: integration tests', (eventSourceName, framewo
     const response = await serverlessExpressInstance(event)
     const expectedResponse = makeResponse({
       eventSourceName,
-      body: JSON.stringify({ data: { name: name } }),
+      body: JSON.stringify({ data: { name } }),
       multiValueHeaders: {
         'content-length': ['29'],
         etag: ['W/"1d-9ERga12t1e/5eBdg3k9zfIvAfWo"']

From 8eb4a449bf94efd7080805cc1b75261abaf1896b Mon Sep 17 00:00:00 2001
From: Michael Harrington <kibiz0r@gmail.com>
Date: Tue, 16 Jul 2024 12:13:01 -0400
Subject: [PATCH 2/3] fix: delegate to http.IncomingMessage for header
 lowercasing/aliasing logic

---
 src/request.js | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/request.js b/src/request.js
index a50e45f3..451a843a 100644
--- a/src/request.js
+++ b/src/request.js
@@ -15,6 +15,11 @@ module.exports = class ServerlessRequest extends http.IncomingMessage {
       destroy: Function.prototype
     })
 
+    // IncomingMessage has a lot of logic for when to lowercase or alias well-known header names,
+    // so we delegate to that logic here
+    const rawHeaders = Object.entries(headers).flat()
+    this._addHeaderLines(rawHeaders, rawHeaders.length)
+
     Object.assign(this, {
       ip: remoteAddress,
       complete: true,
@@ -22,7 +27,6 @@ module.exports = class ServerlessRequest extends http.IncomingMessage {
       httpVersionMajor: '1',
       httpVersionMinor: '1',
       method,
-      headers,
       body,
       url
     })

From bef14dcc33197d17671ee50977d5aadc3d862ae9 Mon Sep 17 00:00:00 2001
From: Michael Harrington <kibiz0r@gmail.com>
Date: Tue, 16 Jul 2024 12:39:05 -0400
Subject: [PATCH 3/3] refactor: slight optimization since we know the size of
 the 2D headers array

---
 src/request.js | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/request.js b/src/request.js
index 451a843a..53450c4e 100644
--- a/src/request.js
+++ b/src/request.js
@@ -17,7 +17,12 @@ module.exports = class ServerlessRequest extends http.IncomingMessage {
 
     // IncomingMessage has a lot of logic for when to lowercase or alias well-known header names,
     // so we delegate to that logic here
-    const rawHeaders = Object.entries(headers).flat()
+    const headerEntries = Object.entries(headers)
+    const rawHeaders = new Array(headerEntries.length * 2)
+    for (let i = 0; i < headerEntries.length; i++) {
+      rawHeaders[i * 2] = headerEntries[i][0]
+      rawHeaders[i * 2 + 1] = headerEntries[i][1]
+    }
     this._addHeaderLines(rawHeaders, rawHeaders.length)
 
     Object.assign(this, {