Move websocket routes into a separate app

This is mostly so we don't have to do any wacky patching but it also
makes it so we don't have to keep checking if the request is a web
socket request every time we add middleware.

src/node/wsRouter.ts

@@ -0,0 +1,57 @@
+import * as express from "express"
+import * as expressCore from "express-serve-static-core"
+import * as http from "http"
+import * as net from "net"
+
+export const handleUpgrade = (app: express.Express, server: http.Server): void => {
+  server.on("upgrade", (req, socket, head) => {
+    socket.on("error", () => socket.destroy())
+
+    req.ws = socket
+    req.head = head
+    req._ws_handled = false
+
+    // Send the request off to be handled by Express.
+    ;(app as any).handle(req, new http.ServerResponse(req), () => {
+      if (!req._ws_handled) {
+        socket.destroy(new Error("Not found"))
+      }
+    })
+  })
+}
+
+export interface WebsocketRequest extends express.Request {
+  ws: net.Socket
+  head: Buffer
+}
+
+interface InternalWebsocketRequest extends WebsocketRequest {
+  _ws_handled: boolean
+}
+
+export type WebSocketHandler = (
+  req: WebsocketRequest,
+  res: express.Response,
+  next: express.NextFunction,
+) => void | Promise<void>
+
+export class WebsocketRouter {
+  public readonly router = express.Router()
+
+  public ws(route: expressCore.PathParams, ...handlers: WebSocketHandler[]): void {
+    this.router.get(
+      route,
+      ...handlers.map((handler) => {
+        const wrapped: express.Handler = (req, res, next) => {
+          ;(req as InternalWebsocketRequest)._ws_handled = true
+          return handler(req as WebsocketRequest, res, next)
+        }
+        return wrapped
+      }),
+    )
+  }
+}
+
+export function Router(): WebsocketRouter {
+  return new WebsocketRouter()
+}