lowercase header keys - fixes #1127

Author: Rich-Harris

.changeset/three-laws-appear.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/kit': patch
+---
+
+Normalize keys of headers from server side requests

packages/kit/src/runtime/server/endpoint.js

@@ -1,3 +1,5 @@
+import { lowercase_keys } from './utils.js';
+
 /**
  * @param {import('types/endpoint').ServerRequest} request
  * @param {import('types/internal').SSREndpoint} route
@@ -19,7 +21,7 @@ export default async function render_route(request, route) {
 			if (typeof response !== 'object') {
 				return {
 					status: 500,
-					body: `Invalid response from route ${request.path}; 
+					body: `Invalid response from route ${request.path};
 						 expected an object, got ${typeof response}`,
 					headers: {}
 				};
@@ -41,15 +43,3 @@ export default async function render_route(request, route) {
 		}
 	}
 }
-
-/** @param {Record<string, string>} obj */
-function lowercase_keys(obj) {
-	/** @type {Record<string, string>} */
-	const clone = {};
-
-	for (const key in obj) {
-		clone[key.toLowerCase()] = obj[key];
-	}
-
-	return clone;
-}

packages/kit/src/runtime/server/index.js

@@ -2,6 +2,7 @@ import render_page from './page/index.js';
 import { render_response } from './page/render.js';
 import render_endpoint from './endpoint.js';
 import { parse_body } from './parse_body/index.js';
+import { lowercase_keys } from './utils.js';
 
 /**
  * @param {import('types/hooks').Incoming} incoming
@@ -22,6 +23,7 @@ export async function respond(incoming, options, state = {}) {
 
 	const incoming_with_body = {
 		...incoming,
+		headers: lowercase_keys(incoming.headers),
 		body: parse_body(incoming)
 	};
 

packages/kit/src/runtime/server/utils.js

@@ -0,0 +1,11 @@
+/** @param {Record<string, string>} obj */
+export function lowercase_keys(obj) {
+	/** @type {Record<string, string>} */
+	const clone = {};
+
+	for (const key in obj) {
+		clone[key.toLowerCase()] = obj[key];
+	}
+
+	return clone;
+}