From 4fbb5880283ba0fad54374baeb572ca706b804e6 Mon Sep 17 00:00:00 2001
From: Joey Thies <jthies@lululemon.com>
Date: Wed, 4 Sep 2024 16:15:36 -0700
Subject: [PATCH] fix(apig-v1-adapter): lowercase request headers

remove log

rework lowercase request header options

performance minded util function

remove unneeded option assignment

add some docs

grammar

tweaks

prefer for..of loop
---
 src/adapters/aws/api-gateway-v1.adapter.ts       | 12 +++++++++++-
 src/core/headers.ts                              |  9 +++++++++
 test/adapters/aws/api-gateway-v1.adapter.spec.ts | 16 ++++++++++++++++
 www/docs/main/adapters/aws/api-gateway-v1.mdx    |  9 +++++++++
 4 files changed, 45 insertions(+), 1 deletion(-)

diff --git a/src/adapters/aws/api-gateway-v1.adapter.ts b/src/adapters/aws/api-gateway-v1.adapter.ts
index f0175511..1724aeea 100644
--- a/src/adapters/aws/api-gateway-v1.adapter.ts
+++ b/src/adapters/aws/api-gateway-v1.adapter.ts
@@ -8,6 +8,7 @@ import type {
   GetResponseAdapterProps,
   OnErrorProps,
 } from '../../contracts';
+import { keysToLowercase } from '../../core';
 import {
   type StripBasePathFn,
   buildStripBasePath,
@@ -42,6 +43,13 @@ export interface ApiGatewayV1Options {
    * @defaultValue true
    */
   throwOnChunkedTransferEncoding?: boolean;
+
+  /**
+   * Emulates the behavior of Node.js `http` module by ensuring all request headers are lowercase.
+   *
+   * @defaultValue false
+   */
+  lowercaseRequestHeaders?: boolean;
 }
 
 /**
@@ -122,7 +130,9 @@ export class ApiGatewayV1Adapter
    */
   public getRequest(event: APIGatewayProxyEvent): AdapterRequest {
     const method = event.httpMethod;
-    const headers = { ...event.headers };
+    const headers = this.options?.lowercaseRequestHeaders
+      ? keysToLowercase(event.headers)
+      : { ...event.headers };
 
     for (const multiValueHeaderKey of Object.keys(
       event.multiValueHeaders || {},
diff --git a/src/core/headers.ts b/src/core/headers.ts
index 1bb43bdc..28e15d8c 100644
--- a/src/core/headers.ts
+++ b/src/core/headers.ts
@@ -151,3 +151,12 @@ export function parseHeaders(
 
   return result;
 }
+
+export function keysToLowercase<T extends Record<string, unknown>>(
+  obj: T,
+): { [K in keyof T as Lowercase<string & K>]: T[K] } {
+  const result: any = {};
+  for (const [k, v] of Object.entries(obj)) result[k.toLowerCase()] = v;
+
+  return result as { [K in keyof T as Lowercase<string & K>]: T[K] };
+}
diff --git a/test/adapters/aws/api-gateway-v1.adapter.spec.ts b/test/adapters/aws/api-gateway-v1.adapter.spec.ts
index 75536483..6e29f3c2 100644
--- a/test/adapters/aws/api-gateway-v1.adapter.spec.ts
+++ b/test/adapters/aws/api-gateway-v1.adapter.spec.ts
@@ -75,6 +75,22 @@ describe(ApiGatewayV1Adapter.name, () => {
       expect(result).toHaveProperty('path', resultPath);
     });
 
+    it('should return lowercase request headers if option `lowercaseRequestHeaders` is `true`', () => {
+      const method = 'GET';
+      const path = '/events';
+
+      adapter = new ApiGatewayV1Adapter({ lowercaseRequestHeaders: true });
+      const event = createApiGatewayV1(method, path);
+      event.headers['Cookie'] = 'test=test;';
+
+      const { headers } = adapter.getRequest(event);
+
+      expect(headers).not.toHaveProperty('Cookie');
+      expect(headers).toHaveProperty('cookie');
+      expect(headers).not.toHaveProperty('Accept');
+      expect(headers).toHaveProperty('accept');
+    });
+
     it('should return the correct mapping for the request when it has no body', () => {
       const method = 'GET';
       const path = '/users';
diff --git a/www/docs/main/adapters/aws/api-gateway-v1.mdx b/www/docs/main/adapters/aws/api-gateway-v1.mdx
index 99ba18a5..0c37415c 100644
--- a/www/docs/main/adapters/aws/api-gateway-v1.mdx
+++ b/www/docs/main/adapters/aws/api-gateway-v1.mdx
@@ -119,6 +119,15 @@ When you configure your API with some `basePath` like `/prod`, you should either
 
 :::
 
+You can also ensure request headers are lowercase like the default behavior of Node.js `http` module by setting the `lowercaseRequestHeaders` option to `true`.
+
+:::caution
+
+ApiGateway may already be ensuring your headers are lowercase but it may be worth confirming in your own system as many libraries in the Node.js ecosystem will assume this lowercasing.
+
+:::
+
+
 ## Usage
 
 To add support to AWS API Gateway V1 you do the following: