Add flag to enable permessage-deflate

Author: code-asher

src/node/cli.ts

@@ -35,6 +35,7 @@ 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 +129,7 @@ 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: { type: "string[]" }, // There is no support for this flag.
   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

@@ -21,6 +21,7 @@ import * as proxyAgent from "./proxy_agent"
 import { register } from "./routes"
 import { humanPath, isFile, open } from "./util"
 import { isChild, wrapper } from "./wrapper"
+import { enableFeature } from "./feature"
 
 export const runVsCodeCli = (args: DefaultedArgs): void => {
   logger.debug("forking vs code cli...")
@@ -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 (enableFeature(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/feature.ts

@@ -0,0 +1,29 @@
+export enum Feature {
+  /** Web socket compression. */
+  PermessageDeflate = "permessage-deflate",
+}
+
+const enabledFeatures: Feature[] = []
+
+/**
+ * Enable the specified feature.
+ *
+ * Return true if the feature was enabled or false if it's invalid.
+ */
+export function enableFeature(feature: string) {
+  for (const key in Feature) {
+    if (Feature[key as keyof typeof Feature] === feature) {
+      enabledFeatures.push(feature as Feature)
+      return true
+    }
+  }
+  return false
+}
+
+/**
+ * Return true if the feature is enabled. Features are always enabled in
+ * development mode to ensure we are testing them.
+ */
+export function isFeatureEnabled(feature: Feature) {
+  return enabledFeatures.includes(feature)
+}

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, isFeatureEnabled } from "../feature"
 import { authenticated, ensureAuthenticated, redirect, replaceTemplates } from "../http"
 import { getMediaMime, pathToFsPath } from "../util"
 import { VscodeProvider } from "../vscode"
@@ -213,7 +214,9 @@ wsRouter.ws("/", ensureAuthenticated, async (req) => {
   // it's stable (see zlib issues).
   // TODO: Parse this header properly.
   const extensions = req.headers["sec-websocket-extensions"]
-  const permessageDeflate = extensions ? extensions.includes("permessage-deflate") && isDevMode : false
+  const permessageDeflate = extensions
+    ? extensions.includes("permessage-deflate") && isFeatureEnabled(Feature.PermessageDeflate)
+    : false
   if (permessageDeflate) {
     responseHeaders.push("Sec-WebSocket-Extensions: permessage-deflate; server_max_window_bits=15")
   }

test/unit/feature.test.ts

@@ -0,0 +1,16 @@
+import { Feature, enableFeature, isFeatureEnabled } from "../../src/node/feature"
+
+describe("feature", () => {
+  it("should have no features enabled", () => {
+    expect(isFeatureEnabled(Feature.PermessageDeflate)).toStrictEqual(false)
+  })
+
+  it("should enable features", () => {
+    expect(enableFeature(Feature.PermessageDeflate)).toStrictEqual(true)
+    expect(isFeatureEnabled(Feature.PermessageDeflate)).toStrictEqual(true)
+  })
+
+  it("should not add invalid features", () => {
+    expect(enableFeature("invalid")).toStrictEqual(false)
+  })
+})