Native support for Websockets

packages/kit/src/exports/public.d.ts

@@ -19,6 +19,8 @@ import {
 } from '../types/private.js';
 import { BuildData, SSRNodeLoader, SSRRoute, ValidatedConfig } from 'types';
 import type { PluginOptions } from '@sveltejs/vite-plugin-svelte';
+import type { IncomingMessage } from 'node:http';
+import type { Duplex } from 'node:stream';
 
 export { PrerenderOption } from '../types/private.js';
 
@@ -315,7 +317,7 @@ export interface KitConfig {
 	/**
 	 * The directory where SvelteKit keeps its stuff, including static assets (such as JS and CSS) and internally-used routes.
 	 *
-	 * If `paths.assets` is specified, there will be two app directories — `${paths.assets}/${appDir}` and `${paths.base}/${appDir}`.
+	 * If `paths.assets` is specified, there will be two app directories - `${paths.assets}/${appDir}` and `${paths.base}/${appDir}`.
 	 * @default "_app"
 	 */
 	appDir?: string;
@@ -548,10 +550,10 @@ export interface KitConfig {
 		/**
 		 * How to respond to HTTP errors encountered while prerendering the app.
 		 *
-		 * - `'fail'` — fail the build
+		 * - `'fail'` - fail the build
 		 * - `'ignore'` - silently ignore the failure and continue
-		 * - `'warn'` — continue, but print a warning
-		 * - `(details) => void` — a custom error handler that takes a `details` object with `status`, `path`, `referrer`, `referenceType` and `message` properties. If you `throw` from this function, the build will fail
+		 * - `'warn'` - continue, but print a warning
+		 * - `(details) => void` - a custom error handler that takes a `details` object with `status`, `path`, `referrer`, `referenceType` and `message` properties. If you `throw` from this function, the build will fail
 		 *
 		 * ```js
 		 * /// file: svelte.config.js
@@ -580,10 +582,10 @@ export interface KitConfig {
 		/**
 		 * How to respond when hash links from one prerendered page to another don't correspond to an `id` on the destination page.
 		 *
-		 * - `'fail'` — fail the build
+		 * - `'fail'` - fail the build
 		 * - `'ignore'` - silently ignore the failure and continue
-		 * - `'warn'` — continue, but print a warning
-		 * - `(details) => void` — a custom error handler that takes a `details` object with `path`, `id`, `referrers` and `message` properties. If you `throw` from this function, the build will fail
+		 * - `'warn'` - continue, but print a warning
+		 * - `(details) => void` - a custom error handler that takes a `details` object with `path`, `id`, `referrers` and `message` properties. If you `throw` from this function, the build will fail
 		 *
 		 * @default "fail"
 		 * @since 1.15.7
@@ -592,10 +594,10 @@ export interface KitConfig {
 		/**
 		 * How to respond when an entry generated by the `entries` export doesn't match the route it was generated from.
 		 *
-		 * - `'fail'` — fail the build
+		 * - `'fail'` - fail the build
 		 * - `'ignore'` - silently ignore the failure and continue
-		 * - `'warn'` — continue, but print a warning
-		 * - `(details) => void` — a custom error handler that takes a `details` object with `generatedFromId`, `entry`, `matchedId` and `message` properties. If you `throw` from this function, the build will fail
+		 * - `'warn'` - continue, but print a warning
+		 * - `(details) => void` - a custom error handler that takes a `details` object with `generatedFromId`, `entry`, `matchedId` and `message` properties. If you `throw` from this function, the build will fail
 		 *
 		 * @default "fail"
 		 * @since 1.16.0
@@ -685,8 +687,8 @@ export interface KitConfig {
  */
 export type Handle = (input: {
 	event: RequestEvent;
-	resolve(event: RequestEvent, opts?: ResolveOptions): MaybePromise<Response>;
-}) => MaybePromise<Response>;
+	resolve(event: RequestEvent, opts?: ResolveOptions): MaybePromise<void | Response>;
+}) => MaybePromise<void | Response>;
 
 /**
  * The server-side [`handleError`](https://svelte.dev/docs/kit/hooks#shared-hooks-handleError) hook runs when an unexpected error is thrown while responding to a request.
@@ -785,9 +787,9 @@ export interface LoadEvent<
 	 *	}
 	 *	```
 	 *
-	 * Setting the same header multiple times (even in separate `load` functions) is an error — you can only set a given header once.
+	 * Setting the same header multiple times (even in separate `load` functions) is an error - you can only set a given header once.
 	 *
-	 * You cannot add a `set-cookie` header with `setHeaders` — use the [`cookies`](https://svelte.dev/docs/kit/@sveltejs-kit#Cookies) API in a server-only `load` function instead.
+	 * You cannot add a `set-cookie` header with `setHeaders` - use the [`cookies`](https://svelte.dev/docs/kit/@sveltejs-kit#Cookies) API in a server-only `load` function instead.
 	 *
 	 * `setHeaders` has no effect when a `load` function runs in the browser.
 	 */
@@ -802,7 +804,7 @@ export interface LoadEvent<
 	/**
 	 * This function declares that the `load` function has a _dependency_ on one or more URLs or custom identifiers, which can subsequently be used with [`invalidate()`](https://svelte.dev/docs/kit/$app-navigation#invalidate) to cause `load` to rerun.
 	 *
-	 * Most of the time you won't need this, as `fetch` calls `depends` on your behalf — it's only necessary if you're using a custom API client that bypasses `fetch`.
+	 * Most of the time you won't need this, as `fetch` calls `depends` on your behalf - it's only necessary if you're using a custom API client that bypasses `fetch`.
 	 *
 	 * URLs can be absolute or relative to the page being loaded, and must be [encoded](https://developer.mozilla.org/en-US/docs/Glossary/percent-encoding).
 	 *
@@ -1076,6 +1078,10 @@ export interface RequestEvent<
 	 * The original request object
 	 */
 	request: Request;
+		/**
+	 * The upgrade request object
+	 */
+	upgrade?: {request: IncomingMessage, socket: Duplex, head: Buffer}
 	/**
 	 * Info about the current route
 	 */
@@ -1103,9 +1109,9 @@ export interface RequestEvent<
 	 *	}
 	 *	```
 	 *
-	 * Setting the same header multiple times (even in separate `load` functions) is an error — you can only set a given header once.
+	 * Setting the same header multiple times (even in separate `load` functions) is an error - you can only set a given header once.
 	 *
-	 * You cannot add a `set-cookie` header with `setHeaders` — use the [`cookies`](https://svelte.dev/docs/kit/@sveltejs-kit#Cookies) API instead.
+	 * You cannot add a `set-cookie` header with `setHeaders` - use the [`cookies`](https://svelte.dev/docs/kit/@sveltejs-kit#Cookies) API instead.
 	 */
 	setHeaders(headers: Record<string, string>): void;
 	/**
@@ -1133,6 +1139,16 @@ export type RequestHandler<
 	RouteId extends string | null = string | null
 > = (event: RequestEvent<Params, RouteId>) => MaybePromise<Response>;
 
+/**
+ * A `(event: UpgradeEvent) => void` function exported from a `+server.js` file with the name UPGRADE and handles server upgrade requests.
+ *
+ * It receives `Params` as the first generic argument, which you can skip by using [generated types](https://svelte.dev/docs/kit/types#Generated-types) instead.
+ */
+export type UpgradeHandler<
+	Params extends Partial<Record<string, string>> = Partial<Record<string, string>>,
+	RouteId extends string | null = string | null
+> = (event: RequestEvent<Params, RouteId>) => MaybePromise<void>;
+
 export interface ResolveOptions {
 	/**
 	 * Applies custom transforms to HTML. If `done` is true, it's the final chunk. Chunks are not guaranteed to be well-formed HTML
@@ -1226,7 +1242,7 @@ export interface ServerLoadEvent<
 	/**
 	 * This function declares that the `load` function has a _dependency_ on one or more URLs or custom identifiers, which can subsequently be used with [`invalidate()`](https://svelte.dev/docs/kit/$app-navigation#invalidate) to cause `load` to rerun.
 	 *
-	 * Most of the time you won't need this, as `fetch` calls `depends` on your behalf — it's only necessary if you're using a custom API client that bypasses `fetch`.
+	 * Most of the time you won't need this, as `fetch` calls `depends` on your behalf - it's only necessary if you're using a custom API client that bypasses `fetch`.
 	 *
 	 * URLs can be absolute or relative to the page being loaded, and must be [encoded](https://developer.mozilla.org/en-US/docs/Glossary/percent-encoding).
 	 *

packages/kit/src/exports/vite/dev/index.js

@@ -43,7 +43,7 @@ export async function dev(vite, vite_config, svelte_config) {
 	globalThis.fetch = (info, init) => {
 		if (typeof info === 'string' && !SCHEME.test(info)) {
 			throw new Error(
-				`Cannot use relative URL (${info}) with global fetch — use \`event.fetch\` instead: https://svelte.dev/docs/kit/web-standards#fetch-apis`
+				`Cannot use relative URL (${info}) with global fetch - use \`event.fetch\` instead: https://svelte.dev/docs/kit/web-standards#fetch-apis`
 			);
 		}
 
@@ -431,6 +431,52 @@ export async function dev(vite, vite_config, svelte_config) {
 		// serving routes with those names. See https://github.com/vitejs/vite/issues/7363
 		remove_static_middlewares(vite.middlewares);
 
+		vite.httpServer?.on('upgrade', async (req, socket, head) => {
+			const base = `${vite.config.server.https ? 'wss' : 'ws'}://${
+				req.headers[':authority'] || req.headers.host
+			}`;
+
+			// we have to import `Server` before calling `set_assets`
+			const { Server } = /** @type {import('types').ServerModule} */ (
+				await vite.ssrLoadModule(`${runtime_base}/server/index.js`, { fixStacktrace: true })
+			);
+
+			const server = new Server(manifest);
+
+			await server.init({
+				env,
+				read: (file) => createReadableStream(from_fs(file))
+			});
+
+			const request = await getRequest({
+				base,
+				request: req
+			});
+
+			await server.respond(
+				request,
+				{
+					getClientAddress: () => {
+						const { remoteAddress } = req.socket;
+						if (remoteAddress) return remoteAddress;
+						throw new Error('Could not determine clientAddress');
+					},
+					read: (file) => {
+						if (file in manifest._.server_assets) {
+							return fs.readFileSync(from_fs(file));
+						}
+
+						return fs.readFileSync(path.join(svelte_config.kit.files.assets, file));
+					},
+					before_handle: (event, config, prerender) => {
+						async_local_storage.enterWith({ event, config, prerender });
+					},
+					emulator
+				},
+				{ request: req, socket, head }
+			);
+		});
+
 		vite.middlewares.use(async (req, res) => {
 			// Vite's base middleware strips out the base path. Restore it
 			const original_url = req.url;
@@ -521,24 +567,28 @@ export async function dev(vite, vite_config, svelte_config) {
 					return;
 				}
 
-				const rendered = await server.respond(request, {
-					getClientAddress: () => {
-						const { remoteAddress } = req.socket;
-						if (remoteAddress) return remoteAddress;
-						throw new Error('Could not determine clientAddress');
-					},
-					read: (file) => {
-						if (file in manifest._.server_assets) {
-							return fs.readFileSync(from_fs(file));
-						}
+				const rendered = await server.respond(
+					request,
+					{
+						getClientAddress: () => {
+							const { remoteAddress } = req.socket;
+							if (remoteAddress) return remoteAddress;
+							throw new Error('Could not determine clientAddress');
+						},
+						read: (file) => {
+							if (file in manifest._.server_assets) {
+								return fs.readFileSync(from_fs(file));
+							}
 
-						return fs.readFileSync(path.join(svelte_config.kit.files.assets, file));
+							return fs.readFileSync(path.join(svelte_config.kit.files.assets, file));
+						},
+						before_handle: (event, config, prerender) => {
+							async_local_storage.enterWith({ event, config, prerender });
+						},
+						emulator
 					},
-					before_handle: (event, config, prerender) => {
-						async_local_storage.enterWith({ event, config, prerender });
-					},
-					emulator
-				});
+					undefined
+				);
 
 				if (rendered.status === 404) {
 					// @ts-expect-error

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

@@ -71,3 +71,4 @@ export function read(asset) {
 
 	throw new Error(`Asset does not exist: ${file}`);
 }
+

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

@@ -7,7 +7,7 @@ import { method_not_allowed } from './utils.js';
  * @param {import('@sveltejs/kit').RequestEvent} event
  * @param {import('types').SSREndpoint} mod
  * @param {import('types').SSRState} state
- * @returns {Promise<Response>}
+ * @returns {Promise<Response | void>}
  */
 export async function render_endpoint(event, mod, state) {
 	const method = /** @type {import('types').HttpMethod} */ (event.request.method);
@@ -40,28 +40,36 @@ export async function render_endpoint(event, mod, state) {
 	}
 
 	try {
-		let response = await handler(
-			/** @type {import('@sveltejs/kit').RequestEvent<Record<string, any>>} */ (event)
-		);
-
-		if (!(response instanceof Response)) {
-			throw new Error(
-				`Invalid response from route ${event.url.pathname}: handler should return a Response object`
+		if (method === 'GET' && event.request.headers.has('upgrade') && event.upgrade && mod.UPGRADE) {
+			console.log('upgrade');
+			await mod.UPGRADE(/** @type {import('@sveltejs/kit').RequestEvent<Record<string, any>>} */ (event));
+		} else {
+			console.log('not upgrade');
+			let response = await handler(
+				/** @type {import('@sveltejs/kit').RequestEvent<Record<string, any>>} */ (event)
 			);
-		}
 
-		if (state.prerendering) {
-			// the returned Response might have immutable Headers
-			// so we should clone them before trying to mutate them
-			response = new Response(response.body, {
-				status: response.status,
-				statusText: response.statusText,
-				headers: new Headers(response.headers)
-			});
-			response.headers.set('x-sveltekit-prerender', String(prerender));
+			if (!(response instanceof Response)) {
+				throw new Error(
+					`Invalid response from route ${event.url.pathname}: handler should return a Response object`
+				);
+			}
+
+			if (state.prerendering) {
+				// the returned Response might have immutable Headers
+				// so we should clone them before trying to mutate them
+				response = new Response(response.body, {
+					status: response.status,
+					statusText: response.statusText,
+					headers: new Headers(response.headers)
+				});
+				response.headers.set('x-sveltekit-prerender', String(prerender));
+			}
+
+			console.log(response);
+
+			return response;
 		}
-
-		return response;
 	} catch (e) {
 		if (e instanceof Redirect) {
 			return new Response(undefined, {

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

@@ -93,12 +93,13 @@ export class Server {
 	/**
 	 * @param {Request} request
 	 * @param {import('types').RequestOptions} options
+	 * @param {{request: import('http').IncomingMessage, socket: import('stream').Duplex , head: Buffer}?} webhookRequest
 	 */
-	async respond(request, options) {
+	async respond(request, options, webhookRequest) {
 		return respond(request, this.#options, this.#manifest, {
 			...options,
 			error: false,
 			depth: 0
-		});
+		}, webhookRequest);
 	}
 }