fixup! fix: ensure we do not rewrite external Origin headers in wrang…

…ler dev

fixtures/worker-app/src/index.js

@@ -15,9 +15,10 @@ export default {
 	async fetch(request) {
 		console.log("request log");
 
-		const { pathname } = new URL(request.url);
+		const { pathname, origin } = new URL(request.url);
 		if (pathname === "/random") return new Response(hexEncode(randomBytes(8)));
 		if (pathname === "/error") throw new Error("Oops!");
+		if (pathname === "/redirect") return Response.redirect(`${origin}/foo`);
 		if (request.headers.get("X-Test-URL") !== null) {
 			return new Response(request.url);
 		}

fixtures/worker-app/tests/index.test.ts

@@ -124,4 +124,19 @@ describe("'wrangler dev' correctly renders pages", () => {
 		expect(text).toContain(`HOST:prod.example.org`);
 		expect(text).toContain(`ORIGIN:http://foo.com`);
 	});
+
+	it("rewrites response headers containing the emulated host", async ({
+		expect,
+	}) => {
+		// This /redirect request will add a Location header that points to prod.example.com/foo
+		// But we should rewrite this back to that of the proxy.
+		const response = await fetch(`http://${ip}:${port}/redirect`, {
+			redirect: "manual",
+		});
+		expect(response.status).toBe(302);
+		expect(await response.text()).toEqual("");
+		expect(response.headers.get("Location")).toEqual(
+			`http://${ip}:${port}/foo`
+		);
+	});
 });

packages/wrangler/templates/startDevWorker/ProxyWorker.ts

@@ -143,7 +143,8 @@ export class ProxyWorker implements DurableObject {
 			// explicitly NOT await-ing this promise, we are in a loop and want to process the whole queue quickly + synchronously
 			void fetch(userWorkerUrl, new Request(request, { headers }))
 				.then((res) => {
-					rewriteUrlRelatedHeaders(headers, innerUrl, outerUrl);
+					res = new Response(res.body, res);
+					rewriteUrlRelatedHeaders(res.headers, innerUrl, outerUrl);
 
 					if (isHtmlResponse(res)) {
 						res = insertLiveReloadScript(request, res, this.env, proxyData);
@@ -305,10 +306,12 @@ function insertLiveReloadScript(
 function rewriteUrlRelatedHeaders(headers: Headers, from: URL, to: URL) {
 	headers.forEach((value, key) => {
 		if (typeof value === "string" && value.includes(from.host)) {
+			console.log("updating", key, value);
 			headers.set(
 				key,
 				value.replaceAll(from.origin, to.origin).replaceAll(from.host, to.host)
 			);
+			console.log("updated", key, headers.get(key));
 		}
 	});
 }