refactor(miniflare): centralize internal paths and move platform proxy endpoint

.changeset/brave-planes-dance.md

@@ -0,0 +1,7 @@
+---
+"miniflare": patch
+---
+
+Move internal proxy endpoint to reserved `/cdn-cgi/` path
+
+The internal HTTP endpoint used by `getPlatformProxy` has been moved to a reserved path. This is an internal change with no impact on the `getPlatformProxy` API.

packages/miniflare/src/index.ts

@@ -133,6 +133,7 @@ import {
 	CacheHeaders,
 	CoreBindings,
 	CoreHeaders,
+	CorePaths,
 	LogLevel,
 	Mutex,
 	SharedHeaders,
@@ -1384,7 +1385,7 @@ export class Miniflare {
 		const { pathname } = new URL(req.url ?? "", "http://localhost");
 
 		// If this is the path for live-reload, handle the request
-		if (pathname === "/cdn-cgi/mf/reload") {
+		if (pathname === CorePaths.LIVE_RELOAD) {
 			this.#liveReloadServer.handleUpgrade(req, socket, head, (ws) => {
 				this.#liveReloadServer.emit("connection", ws, req);
 			});

packages/miniflare/src/plugins/core/constants.ts

@@ -1,3 +1,4 @@
+import { CorePaths } from "../../workers";
 import type {
 	DoRawQueryResult,
 	DoSqlWithParams,
@@ -12,9 +13,9 @@ export const SERVICE_LOCAL_EXPLORER = `${CORE_PLUGIN_NAME}:local-explorer`;
 // Disk service for local explorer UI assets
 export const LOCAL_EXPLORER_DISK = `${CORE_PLUGIN_NAME}:local-explorer-disk`;
 // URL path prefix where the local explorer UI is served
-export const LOCAL_EXPLORER_BASE_PATH = "/cdn-cgi/explorer";
+export const LOCAL_EXPLORER_BASE_PATH = CorePaths.EXPLORER;
 // URL path prefix for the local explorer API endpoints
-export const LOCAL_EXPLORER_API_PATH = `${LOCAL_EXPLORER_BASE_PATH}/api`;
+export const LOCAL_EXPLORER_API_PATH = `${CorePaths.EXPLORER}/api`;
 // Service prefix for all regular user workers
 const SERVICE_USER_PREFIX = `${CORE_PLUGIN_NAME}:user`;
 // Service prefix for `workerd`'s builtin services (network, external, disk)

packages/miniflare/src/plugins/core/proxy/client.ts

@@ -10,6 +10,7 @@ import { prefixStream, readPrefix } from "../../../shared";
 import {
 	Awaitable,
 	CoreHeaders,
+	CorePaths,
 	createHTTPReducers,
 	createHTTPRevivers,
 	isDurableObjectStub,
@@ -97,7 +98,10 @@ export class ProxyClient {
 	#bridge: ProxyClientBridge;
 
 	constructor(runtimeEntryURL: URL, dispatchFetch: DispatchFetch) {
-		this.#bridge = new ProxyClientBridge(runtimeEntryURL, dispatchFetch);
+		this.#bridge = new ProxyClientBridge(
+			new URL(CorePaths.PLATFORM_PROXY, runtimeEntryURL),
+			dispatchFetch
+		);
 	}
 
 	// Lazily initialise proxies as required
@@ -120,7 +124,7 @@ export class ProxyClient {
 	setRuntimeEntryURL(runtimeEntryURL: URL) {
 		// This function will be called whenever the runtime restarts. The URL may
 		// be different if the port has changed.
-		this.#bridge.url = runtimeEntryURL;
+		this.#bridge.url = new URL(CorePaths.PLATFORM_PROXY, runtimeEntryURL);
 	}
 
 	dispose(): Promise<void> {
@@ -720,9 +724,12 @@ class ProxyStubHandler<T extends object>
 	#fetcherFetchCall(args: unknown[]) {
 		// @ts-expect-error `...args` isn't type-safe here, but `undici` should
 		//  validate types at runtime, and throw appropriate errors
-		const request = new Request(...args);
+		const userRequest = new Request(...args);
+		// Create a new request with the proxy URL, preserving the original request
+		const request = new Request(this.bridge.url, userRequest);
 		// If adding new headers here, remember to `delete()` them in `ProxyServer`
 		// before calling `fetch()`.
+		request.headers.set(CoreHeaders.OP_ORIGINAL_URL, userRequest.url);
 		request.headers.set(CoreHeaders.OP_SECRET, PROXY_SECRET_HEX);
 		request.headers.set(CoreHeaders.OP, ProxyOps.CALL);
 		request.headers.set(CoreHeaders.OP_TARGET, this.#stringifiedTarget);

packages/miniflare/src/plugins/core/proxy/fetch-sync.ts

@@ -50,18 +50,18 @@ let dispatcher;
 
 port.addEventListener("message", async (event) => {
   const { id, method, url, headers, body } = event.data;
-  if (dispatcherUrl !== url) {
-    dispatcherUrl = url;
-    dispatcher = new Pool(url, {
-      connect: { rejectUnauthorized: false },
-      // Disable timeouts for local dev — long-running responses (streaming,
+  try {
+    if (dispatcherUrl !== url) {
+      dispatcherUrl = url;
+      dispatcher = new Pool(new URL(url).origin, {
+        connect: { rejectUnauthorized: false },
+              // Disable timeouts for local dev — long-running responses (streaming,
       // slow uploads, long-polling) should not be killed by undici defaults.
       headersTimeout: 0,
       bodyTimeout: 0,
-    });
-  }
-  headers["${CoreHeaders.OP_SYNC}"] = "true";
-  try {
+      });
+    }
+    headers["${CoreHeaders.OP_SYNC}"] = "true";
     // body cannot be a ReadableStream, so no need to specify duplex
     const response = await fetch(url, { method, headers, body, dispatcher });
     const responseBody = response.headers.get("${CoreHeaders.OP_RESULT_TYPE}") === "ReadableStream"
@@ -86,9 +86,10 @@ port.addEventListener("message", async (event) => {
       // If error failed to serialise, post simplified version
       port.postMessage({ id, error: new Error(String(error)) });
     }
+  } finally {
+    Atomics.store(notifyHandle, /* index */ 0, /* value */ 1);
+    Atomics.notify(notifyHandle, /* index */ 0);
   }
-  Atomics.store(notifyHandle, /* index */ 0, /* value */ 1);
-  Atomics.notify(notifyHandle, /* index */ 0);
 });
 
 port.start();

packages/miniflare/src/workers/core/constants.ts

@@ -1,3 +1,24 @@
+/**
+ * Reserved `/cdn-cgi/` paths for internal Miniflare endpoints.
+ * These paths are reserved by Cloudflare's network and won't conflict with user routes.
+ */
+export const CorePaths = {
+	/** Magic proxy used by getPlatformProxy */
+	PLATFORM_PROXY: "/cdn-cgi/platform-proxy",
+	/** Trigger scheduled event handlers */
+	SCHEDULED: "/cdn-cgi/handler/scheduled",
+	/** Trigger email event handlers */
+	EMAIL: "/cdn-cgi/handler/email",
+	/** Handler path prefix for validation */
+	HANDLER_PREFIX: "/cdn-cgi/handler/",
+	/** Live reload WebSocket endpoint */
+	LIVE_RELOAD: "/cdn-cgi/mf/reload",
+	/** Local explorer UI and API */
+	EXPLORER: "/cdn-cgi/explorer",
+	/** Legacy way to trigger scheduled event handlers */
+	LEGACY_SCHEDULED: "/cdn-cgi/mf/scheduled",
+} as const;
+
 export const CoreHeaders = {
 	CUSTOM_FETCH_SERVICE: "MF-Custom-Fetch-Service",
 	CUSTOM_NODE_SERVICE: "MF-Custom-Node-Service",
@@ -25,6 +46,7 @@ export const CoreHeaders = {
 	OP_SYNC: "MF-Op-Sync",
 	OP_STRINGIFIED_SIZE: "MF-Op-Stringified-Size",
 	OP_RESULT_TYPE: "MF-Op-Result-Type",
+	OP_ORIGINAL_URL: "MF-Op-Original-URL",
 } as const;
 
 export const CoreBindings = {

packages/miniflare/src/workers/core/entry.worker.ts

@@ -9,9 +9,8 @@ import {
 	yellow,
 } from "kleur/colors";
 import { HttpError, LogLevel, SharedHeaders } from "miniflare:shared";
-import { LOCAL_EXPLORER_BASE_PATH } from "../../plugins/core/constants";
 import { isCompressedByCloudflareFL } from "../../shared/mime-types";
-import { CoreBindings, CoreHeaders } from "./constants";
+import { CoreBindings, CoreHeaders, CorePaths } from "./constants";
 import { handleEmail } from "./email";
 import { STATUS_CODES } from "./http";
 import { matchRoutes, WorkerRoute } from "./routing";
@@ -469,9 +468,14 @@ export default <ExportedHandler<Env>>{
 				};
 		request = new Request(request, { cf });
 
-		// The magic proxy client (used by getPlatformProxy) will always specify an operation
-		const isProxy = request.headers.get(CoreHeaders.OP) !== null;
-		if (isProxy) return handleProxy(request, env);
+		// The magic proxy client (used by getPlatformProxy)
+		if (new URL(request.url).pathname === CorePaths.PLATFORM_PROXY) {
+			if (request.headers.get(CoreHeaders.OP) !== null) {
+				return handleProxy(request, env);
+			}
+
+			return new Response("Invalid proxy request", { status: 400 });
+		}
 
 		// `dispatchFetch()` will always inject this header. When
 		// calling this function, we never want to display the pretty-error page.
@@ -487,8 +491,8 @@ export default <ExportedHandler<Env>>{
 			if (env[CoreBindings.SERVICE_LOCAL_EXPLORER]) {
 				const preRewriteUrl = new URL(request.url);
 				if (
-					preRewriteUrl.pathname === LOCAL_EXPLORER_BASE_PATH ||
-					preRewriteUrl.pathname.startsWith(`${LOCAL_EXPLORER_BASE_PATH}/`)
+					preRewriteUrl.pathname === CorePaths.EXPLORER ||
+					preRewriteUrl.pathname.startsWith(`${CorePaths.EXPLORER}/`)
 				) {
 					validateLocalExplorerRequest(
 						request,
@@ -514,18 +518,18 @@ export default <ExportedHandler<Env>>{
 		try {
 			if (env[CoreBindings.SERVICE_LOCAL_EXPLORER]) {
 				if (
-					url.pathname === LOCAL_EXPLORER_BASE_PATH ||
-					url.pathname.startsWith(`${LOCAL_EXPLORER_BASE_PATH}/`)
+					url.pathname === CorePaths.EXPLORER ||
+					url.pathname.startsWith(`${CorePaths.EXPLORER}/`)
 				) {
 					return await env[CoreBindings.SERVICE_LOCAL_EXPLORER].fetch(request);
 				}
 			}
 			if (env[CoreBindings.TRIGGER_HANDLERS]) {
 				if (
-					url.pathname === "/cdn-cgi/handler/scheduled" ||
-					/* legacy URL path */ url.pathname === "/cdn-cgi/mf/scheduled"
+					url.pathname === CorePaths.SCHEDULED ||
+					/* legacy URL path */ url.pathname === CorePaths.LEGACY_SCHEDULED
 				) {
-					if (url.pathname === "/cdn-cgi/mf/scheduled") {
+					if (url.pathname === CorePaths.LEGACY_SCHEDULED) {
 						ctx.waitUntil(
 							env[CoreBindings.SERVICE_LOOPBACK].fetch(
 								"http://localhost/core/log",
@@ -534,15 +538,15 @@ export default <ExportedHandler<Env>>{
 									headers: {
 										[SharedHeaders.LOG_LEVEL]: LogLevel.WARN.toString(),
 									},
-									body: `Triggering scheduled handlers via a request to \`/cdn-cgi/mf/scheduled\` is deprecated, and will be removed in a future version of Miniflare. Instead, send a request to \`/cdn-cgi/handler/scheduled\``,
+									body: `Triggering scheduled handlers via a request to \`${CorePaths.LEGACY_SCHEDULED}\` is deprecated, and will be removed in a future version of Miniflare. Instead, send a request to \`${CorePaths.SCHEDULED}\``,
 								}
 							)
 						);
 					}
 					return await handleScheduled(url.searchParams, service);
 				}
 
-				if (url.pathname === "/cdn-cgi/handler/email") {
+				if (url.pathname === CorePaths.EMAIL) {
 					return await handleEmail(
 						url.searchParams,
 						request,
@@ -552,9 +556,9 @@ export default <ExportedHandler<Env>>{
 					);
 				}
 
-				if (url.pathname.startsWith("/cdn-cgi/handler/")) {
+				if (url.pathname.startsWith(CorePaths.HANDLER_PREFIX)) {
 					return new Response(
-						`"${url.pathname}" is not a valid handler. Did you mean to use "/cdn-cgi/handler/scheduled" or "/cdn-cgi/handler/email"?`,
+						`"${url.pathname}" is not a valid handler. Did you mean to use "${CorePaths.SCHEDULED}" or "${CorePaths.EMAIL}"?`,
 						{ status: 404 }
 					);
 				}

packages/miniflare/src/workers/core/proxy.worker.ts

@@ -270,14 +270,17 @@ export class ProxyServer implements DurableObject {
 
 			// See `isFetcherFetch()` comment for why this special
 			if (isFetcherFetch(targetName, keyHeader)) {
-				const originalUrl = request.headers.get(CoreHeaders.ORIGINAL_URL);
+				const originalUrl =
+					request.headers.get(CoreHeaders.OP_ORIGINAL_URL) ??
+					request.headers.get(CoreHeaders.ORIGINAL_URL);
 				const url = new URL(originalUrl ?? request.url);
 				// Create a new request to allow header mutation and use original URL
 				request = new Request(url, request);
 				request.headers.delete(CoreHeaders.OP_SECRET);
 				request.headers.delete(CoreHeaders.OP);
 				request.headers.delete(CoreHeaders.OP_TARGET);
 				request.headers.delete(CoreHeaders.OP_KEY);
+				request.headers.delete(CoreHeaders.OP_ORIGINAL_URL);
 				request.headers.delete(CoreHeaders.ORIGINAL_URL);
 				request.headers.delete(CoreHeaders.DISABLE_PRETTY_ERROR);
 				return func.call(target, request);

packages/miniflare/test/plugins/core/proxy/client.spec.ts

@@ -5,6 +5,7 @@ import { text } from "node:stream/consumers";
 import { ReadableStream, WritableStream } from "node:stream/web";
 import util from "node:util";
 import {
+	CorePaths,
 	DeferredPromise,
 	fetch,
 	MessageEvent,
@@ -56,6 +57,28 @@ describe("ProxyClient", () => {
 		expect(event.data).toBe("echo:hello");
 	});
 
+	test("preserves original URL for service binding fetch", async ({
+		expect,
+	}) => {
+		const mf = new Miniflare({
+			script: nullScript,
+			serviceBindings: {
+				CUSTOM(request: Request) {
+					return new Response(request.url);
+				},
+			},
+		});
+		useDispose(mf);
+
+		const { CUSTOM } = await mf.getBindings<{
+			CUSTOM: ReplaceWorkersTypes<Fetcher>;
+		}>();
+
+		const url = "https://placeholder/path?query=value";
+		const res = await CUSTOM.fetch(url);
+		expect(await res.text()).toBe(url);
+	});
+
 	test("supports serialising multiple ReadableStreams, Blobs and Files", async ({
 		expect,
 	}) => {
@@ -329,32 +352,38 @@ describe("ProxyClient", () => {
 		const mf = new Miniflare({ script: nullScript });
 		useDispose(mf);
 		const url = await mf.ready;
+		const proxyUrl = new URL(CorePaths.PLATFORM_PROXY, url);
 
 		// Check validates `Host` header
 		const statusPromise = new DeferredPromise<number>();
 		const req = http.get(
-			url,
+			proxyUrl,
 			{ setHost: false, headers: { "MF-Op": "GET", Host: "localhost" } },
 			(res) => statusPromise.resolve(res.statusCode ?? 0)
 		);
 		req.on("error", (error) => statusPromise.reject(error));
 		expect(await statusPromise).toBe(401);
 
 		// Check validates `MF-Op-Secret` header
-		let res = await fetch(url, {
+		let res = await fetch(proxyUrl, {
 			headers: { "MF-Op": "GET" }, // (missing)
 		});
 		expect(res.status).toBe(401);
 		await res.arrayBuffer(); // (drain)
-		res = await fetch(url, {
+		res = await fetch(proxyUrl, {
 			headers: { "MF-Op": "GET", "MF-Op-Secret": "aaaa" }, // (too short)
 		});
 		expect(res.status).toBe(401);
 		await res.arrayBuffer(); // (drain)
-		res = await fetch(url, {
+		res = await fetch(proxyUrl, {
 			headers: { "MF-Op": "GET", "MF-Op-Secret": "a".repeat(32) }, // (wrong)
 		});
 		expect(res.status).toBe(401);
 		await res.arrayBuffer(); // (drain)
+
+		// Check requests to proxy path without MF-Op header return 400
+		res = await fetch(proxyUrl);
+		expect(res.status).toBe(400);
+		await res.arrayBuffer(); // (drain)
 	});
 });