Add proxy provider

It'll be able to handle /proxy requests as well as subdomains.

src/node/app/proxy.ts

@@ -0,0 +1,83 @@
+import * as http from "http"
+import { HttpCode, HttpError } from "../../common/http"
+import { AuthType, HttpProvider, HttpProviderOptions, HttpResponse, Route } from "../http"
+
+/**
+ * Proxy HTTP provider.
+ */
+export class ProxyHttpProvider extends HttpProvider {
+  public constructor(options: HttpProviderOptions, private readonly proxyDomains: string[]) {
+    super(options)
+  }
+
+  public async handleRequest(route: Route): Promise<HttpResponse> {
+    if (this.options.auth !== AuthType.Password || route.requestPath !== "/index.html") {
+      throw new HttpError("Not found", HttpCode.NotFound)
+    }
+    const payload = this.proxy(route.base.replace(/^\//, ""))
+    if (!payload) {
+      throw new HttpError("Not found", HttpCode.NotFound)
+    }
+    return payload
+  }
+
+  public async getRoot(route: Route, error?: Error): Promise<HttpResponse> {
+    const response = await this.getUtf8Resource(this.rootPath, "src/browser/pages/login.html")
+    response.content = response.content.replace(/{{ERROR}}/, error ? `<div class="error">${error.message}</div>` : "")
+    return this.replaceTemplates(route, response)
+  }
+
+  /**
+   * Return a response if the request should be proxied. Anything that ends in a
+   * proxy domain and has a subdomain should be proxied. The port is found in
+   * the top-most subdomain.
+   *
+   * For example, if the proxy domain is `coder.com` then `8080.coder.com` and
+   * `test.8080.coder.com` will both proxy to `8080` but `8080.test.coder.com`
+   * will have an error because `test` isn't a port. If the proxy domain was
+   * `test.coder.com` then it would work.
+   */
+  public maybeProxy(request: http.IncomingMessage): HttpResponse | undefined {
+    const host = request.headers.host
+    if (!host || !this.proxyDomains) {
+      return undefined
+    }
+
+    const proxyDomain = this.proxyDomains.find((d) => host.endsWith(d))
+    if (!proxyDomain) {
+      return undefined
+    }
+
+    const proxyDomainLength = proxyDomain.split(".").length
+    const portStr = host
+      .split(".")
+      .slice(0, -proxyDomainLength)
+      .pop()
+
+    if (!portStr) {
+      return undefined
+    }
+
+    return this.proxy(portStr)
+  }
+
+  private proxy(portStr: string): HttpResponse {
+    if (!portStr) {
+      return {
+        code: HttpCode.BadRequest,
+        content: "Port must be provided",
+      }
+    }
+    const port = parseInt(portStr, 10)
+    if (isNaN(port)) {
+      return {
+        code: HttpCode.BadRequest,
+        content: `"${portStr}" is not a valid number`,
+      }
+    }
+    return {
+      code: HttpCode.Ok,
+      content: `will proxy this to ${port}`,
+    }
+  }
+}

src/node/entry.ts

@@ -5,6 +5,7 @@ import { CliMessage } from "../../lib/vscode/src/vs/server/ipc"
 import { ApiHttpProvider } from "./app/api"
 import { DashboardHttpProvider } from "./app/dashboard"
 import { LoginHttpProvider } from "./app/login"
+import { ProxyHttpProvider } from "./app/proxy"
 import { StaticHttpProvider } from "./app/static"
 import { UpdateHttpProvider } from "./app/update"
 import { VscodeHttpProvider } from "./app/vscode"
@@ -35,14 +36,6 @@ const main = async (args: Args): Promise<void> => {
   const auth = args.auth || AuthType.Password
   const originalPassword = auth === AuthType.Password && (process.env.PASSWORD || (await generatePassword()))
 
-  /**
-   * Domains can be in the form `coder.com` or `*.coder.com`. Either way,
-   * `[number].coder.com` will be proxied to `number`.
-   */
-  const normalizeProxyDomains = (domains?: string[]): string[] => {
-    return domains ? domains.map((d) => d.replace(/^\*\./, "")).filter((d, i) => domains.indexOf(d) === i) : []
-  }
-
   // Spawn the main HTTP server.
   const options: HttpServerOptions = {
     auth,
@@ -50,7 +43,6 @@ const main = async (args: Args): Promise<void> => {
     host: args.host || (args.auth === AuthType.Password && typeof args.cert !== "undefined" ? "0.0.0.0" : "localhost"),
     password: originalPassword ? hash(originalPassword) : undefined,
     port: typeof args.port !== "undefined" ? args.port : process.env.PORT ? parseInt(process.env.PORT, 10) : 8080,
-    proxyDomains: normalizeProxyDomains(args["proxy-domain"]),
     socket: args.socket,
     ...(args.cert && !args.cert.value
       ? await generateCertificate()
@@ -64,13 +56,23 @@ const main = async (args: Args): Promise<void> => {
     throw new Error("--cert-key is missing")
   }
 
+  /**
+   * Domains can be in the form `coder.com` or `*.coder.com`. Either way,
+   * `[number].coder.com` will be proxied to `number`.
+   */
+  const proxyDomains = args["proxy-domain"]
+    ? args["proxy-domain"].map((d) => d.replace(/^\*\./, "")).filter((d, i, arr) => arr.indexOf(d) === i)
+    : []
+
   const httpServer = new HttpServer(options)
   const vscode = httpServer.registerHttpProvider("/", VscodeHttpProvider, args)
   const api = httpServer.registerHttpProvider("/api", ApiHttpProvider, httpServer, vscode, args["user-data-dir"])
   const update = httpServer.registerHttpProvider("/update", UpdateHttpProvider, !args["disable-updates"])
+  const proxy = httpServer.registerHttpProvider("/proxy", ProxyHttpProvider, proxyDomains)
   httpServer.registerHttpProvider("/login", LoginHttpProvider)
   httpServer.registerHttpProvider("/static", StaticHttpProvider)
   httpServer.registerHttpProvider("/dashboard", DashboardHttpProvider, api, update)
+  httpServer.registerProxy(proxy)
 
   ipcMain().onDispose(() => httpServer.dispose())
 
@@ -100,13 +102,11 @@ const main = async (args: Args): Promise<void> => {
     logger.info("  - Not serving HTTPS")
   }
 
-  if (options.proxyDomains && options.proxyDomains.length === 1) {
-    logger.info(`  - Proxying *.${options.proxyDomains[0]}`)
-  } else if (options.proxyDomains && options.proxyDomains.length > 1) {
+  if (proxyDomains.length === 1) {
+    logger.info(`  - Proxying *.${proxyDomains[0]}`)
+  } else if (proxyDomains && proxyDomains.length > 1) {
     logger.info("  - Proxying the following domains:")
-    options.proxyDomains.forEach((domain) => {
-      logger.info(`    - *.${domain}`)
-    })
+    proxyDomains.forEach((domain) => logger.info(`    - *.${domain}`))
   }
 
   logger.info(`Automatic updates are ${update.enabled ? "enabled" : "disabled"}`)

src/node/http.ts

@@ -99,7 +99,6 @@ export interface HttpServerOptions {
   readonly commit?: string
   readonly host?: string
   readonly password?: string
-  readonly proxyDomains?: string[]
   readonly port?: number
   readonly socket?: string
 }
@@ -395,6 +394,10 @@ export interface HttpProvider3<A1, A2, A3, T> {
   new (options: HttpProviderOptions, a1: A1, a2: A2, a3: A3): T
 }
 
+export interface HttpProxyProvider {
+  maybeProxy(request: http.IncomingMessage): HttpResponse | undefined
+}
+
 /**
  * An HTTP server. Its main role is to route incoming HTTP requests to the
  * appropriate provider for that endpoint then write out the response. It also
@@ -407,6 +410,7 @@ export class HttpServer {
   private readonly providers = new Map<string, HttpProvider>()
   private readonly heart: Heart
   private readonly socketProvider = new SocketProxyProvider()
+  private proxy?: HttpProxyProvider
 
   public constructor(private readonly options: HttpServerOptions) {
     this.heart = new Heart(path.join(xdgLocalDir, "heartbeat"), async () => {
@@ -481,6 +485,14 @@ export class HttpServer {
     return p
   }
 
+  /**
+   * Register a provider as a proxy. It will be consulted before any other
+   * provider.
+   */
+  public registerProxy(proxy: HttpProxyProvider): void {
+    this.proxy = proxy
+  }
+
   /**
    * Start listening on the specified port.
    */
@@ -551,8 +563,12 @@ export class HttpServer {
         response.end()
       }
     }
+
     try {
-      const payload = this.maybeRedirect(request, route) || (await route.provider.handleRequest(route, request))
+      const payload =
+        (this.proxy && this.proxy.maybeProxy(request)) ||
+        this.maybeRedirect(request, route) ||
+        (await route.provider.handleRequest(route, request))
       if (!payload) {
         throw new HttpError("Not found", HttpCode.NotFound)
       }