feat: make header name case insensitive

Author: coderbyheart

src/corsHeaders.ts

@@ -1,12 +1,14 @@
 import type { APIGatewayProxyEventHeaders } from 'aws-lambda'
+import { parseHeaders } from './parseHeaders.js'
 
 const allowedDomains = [
 	/^https?:\/\/localhost:/,
 	/^https:\/\/hello\.nrfcloud\.com$/,
 ]
 const defaultOrigin = 'https://hello.nrfcloud.com'
 const origin = (event: { headers: APIGatewayProxyEventHeaders }): string => {
-	const origin = event.headers.origin ?? defaultOrigin.toString()
+	const origin =
+		parseHeaders(event.headers).get('origin') ?? defaultOrigin.toString()
 
 	if (allowedDomains.find((rx) => rx.test(origin)) !== undefined) return origin
 

src/parseHeaders.spec.ts

@@ -0,0 +1,24 @@
+import assert from 'assert'
+import { describe, it } from 'node:test'
+import { parseHeaders } from './parseHeaders.js'
+
+void describe('parseHeaders()', () => {
+	void it('should parse both lowercase and uppercase headers', () => {
+		const headers = {
+			'content-type': 'application/json',
+			'Content-Length': '1234',
+			'x-custom-header': 'value',
+		}
+
+		const parsedHeaders = parseHeaders(headers)
+
+		assert.deepEqual(
+			parsedHeaders,
+			new Map([
+				['content-type', 'application/json'],
+				['content-length', '1234'],
+				['x-custom-header', 'value'],
+			]),
+		)
+	})
+})

src/parseHeaders.ts

@@ -0,0 +1,13 @@
+/**
+ * Returns a Map of headers with keys in lowercase.
+ * This is useful for consistent header handling, especially in environments
+ * where header keys may be case-insensitive.
+ */
+export const parseHeaders = (
+	headers: Record<string, string | undefined>,
+): Map<string, string | null> => {
+	return Object.entries(headers).reduce((h, [key, value]) => {
+		h.set(key.toLowerCase(), value ?? null)
+		return h
+	}, new Map())
+}

src/validateInput.ts

@@ -10,6 +10,7 @@ import type {
 	APIGatewayProxyStructuredResultV2,
 	Context,
 } from 'aws-lambda'
+import { parseHeaders } from './parseHeaders.js'
 import { tryAsJSON } from './tryAsJSON.js'
 
 export class ValidationFailedError extends Error {
@@ -34,12 +35,10 @@ export const validateInput = <Schema extends TSchema>(
 	return {
 		before: async (req) => {
 			let reqBody = {}
-			if (
-				(req.event.headers?.['content-type'] ?? '').includes(
-					'application/json',
-				) &&
-				parseInt(req.event.headers?.['content-length'] ?? '0', 10) > 0
-			) {
+			const headers = parseHeaders(req.event.headers)
+			const contentType = headers.get('content-type') ?? ''
+			const contentLength = parseInt(headers.get('content-length') ?? '0', 10)
+			if (contentType.includes('application/json') && contentLength > 0) {
 				reqBody = tryAsJSON(req.event.body) ?? {}
 			}
 			const input = mapInput?.(req.event) ?? {

src/validateResponse.ts

@@ -5,6 +5,7 @@ import {
 import type middy from '@middy/core'
 import type { TSchema } from '@sinclair/typebox'
 import type { ValueError } from '@sinclair/typebox/errors'
+import { parseHeaders } from './parseHeaders.js'
 import { tryAsJSON } from './tryAsJSON.js'
 import { ValidationFailedError } from './validateInput.js'
 
@@ -25,13 +26,13 @@ export const validateResponse = <ResponseSchema extends TSchema>(
 	return {
 		after: async (req) => {
 			const body = req.response?.body
+			const headers = parseHeaders(req.response.headers)
+			const contentType = headers.get('content-type') ?? ''
+
 			if ((body?.length ?? 0) === 0) {
 				console.debug(`[validateResponse]`, `Response body is empty`)
 			}
-			if (
-				(req.response.headers['content-type']?.includes('application/json') ??
-					false) === false
-			) {
+			if ((contentType?.includes('application/json') ?? false) === false) {
 				console.debug(`[validateResponse]`, `Response body is not JSON`)
 			}
 			const maybeValid = validator(tryAsJSON(req.response.body))