Add flag to enable permessage-deflate

Author: code-asher

src/node/cli.ts

@@ -6,6 +6,11 @@ import * as path from "path"
 import { Args as VsArgs } from "../../typings/ipc"
 import { canConnect, generateCertificate, generatePassword, humanPath, paths } from "./util"
 
+export enum Feature {
+  /** Web socket compression. */
+  PermessageDeflate = "permessage-deflate",
+}
+
 export enum AuthType {
   Password = "password",
   None = "none",
@@ -35,6 +40,7 @@ export interface Args extends VsArgs {
   "cert-key"?: string
   "disable-telemetry"?: boolean
   "disable-update-check"?: boolean
+  enable?: string[]
   help?: boolean
   host?: string
   json?: boolean
@@ -128,6 +134,9 @@ const options: Options<Required<Args>> = {
       "Disable update check. Without this flag, code-server checks every 6 hours against the latest github release and \n" +
       "then notifies you once every week that a new release is available.",
   },
+  // --enable can be used to enable experimental features. These features
+  // provide no guarantees.
+  enable: { type: "string[]" },
   help: { type: "boolean", short: "h", description: "Show this output." },
   json: { type: "boolean" },
   open: { type: "boolean", description: "Open in browser on startup. Does not work remotely." },

src/node/entry.ts

@@ -8,6 +8,7 @@ import { createApp, ensureAddress } from "./app"
 import {
   AuthType,
   DefaultedArgs,
+  Feature,
   optionDescriptions,
   parse,
   readConfigFile,
@@ -146,6 +147,17 @@ const main = async (args: DefaultedArgs): Promise<void> => {
     }
   }
 
+  if (args.enable && args.enable.length > 0) {
+    logger.info("Enabling features:")
+    args.enable.forEach((feature) => {
+      if (Object.values(Feature).includes(feature as Feature)) {
+        logger.info(`  - "${feature}"`)
+      } else {
+        logger.error(`  X "${feature}" (unknown feature)`)
+      }
+    })
+  }
+
   if (!args.socket && args.open) {
     // The web socket doesn't seem to work if browsing with 0.0.0.0.
     const openAddress = serverAddress.replace("://0.0.0.0", "://localhost")

src/node/routes/vscode.ts

@@ -8,6 +8,7 @@ import { Emitter } from "../../common/emitter"
 import { HttpCode, HttpError } from "../../common/http"
 import { getFirstString } from "../../common/util"
 import { isDevMode, rootPath, version } from "../constants"
+import { Feature } from "../cli"
 import { authenticated, ensureAuthenticated, redirect, replaceTemplates } from "../http"
 import { getMediaMime, pathToFsPath } from "../util"
 import { VscodeProvider } from "../vscode"
@@ -209,14 +210,21 @@ wsRouter.ws("/", ensureAuthenticated, async (req) => {
     `Sec-WebSocket-Accept: ${reply}`,
   ]
 
+  // See if the browser reports it supports web socket compression.
   // TODO: Parse this header properly.
   const extensions = req.headers["sec-websocket-extensions"]
-  const permessageDeflate = extensions ? extensions.includes("permessage-deflate") : false
-  if (permessageDeflate) {
+  const isCompressionSupported = extensions ? extensions.includes("permessage-deflate") : false
+
+  // TODO: For now we only use compression if the user enables it.
+  const isCompressionEnabled = !!req.args.enable?.includes(Feature.PermessageDeflate)
+
+  const useCompression = isCompressionEnabled && isCompressionSupported
+  if (useCompression) {
+    // This response header tells the browser the server supports compression.
     responseHeaders.push("Sec-WebSocket-Extensions: permessage-deflate; server_max_window_bits=15")
   }
 
   req.ws.write(responseHeaders.join("\r\n") + "\r\n\r\n")
 
-  await vscode.sendWebsocket(req.ws, req.query, permessageDeflate)
+  await vscode.sendWebsocket(req.ws, req.query, useCompression)
 })

test/unit/cli.test.ts

@@ -39,6 +39,10 @@ describe("parser", () => {
   it("should parse all available options", () => {
     expect(
       parse([
+        "--enable",
+        "feature1",
+        "--enable",
+        "feature2",
         "--bind-addr=192.169.0.1:8080",
         "--auth",
         "none",
@@ -82,6 +86,7 @@ describe("parser", () => {
       cert: {
         value: path.resolve("baz"),
       },
+      enable: ["feature1", "feature2"],
       "extensions-dir": path.resolve("foo"),
       "extra-builtin-extensions-dir": [path.resolve("bazzle")],
       "extra-extensions-dir": [path.resolve("nozzle")],