Import X-Download-Options (ienoopen) middleware

This imports the [ienoopen package][0] into this repo. You can find its
prior history in the old repo's source code, but now I'm moving Helmet
to be a monorepo.

[0]: https://github.com/helmetjs/ienoopen

bin/.eslintrc.json

@@ -0,0 +1,5 @@
+{
+  "env": {
+    "es6": true
+  }
+}

bin/build-middleware-package.js

@@ -0,0 +1,81 @@
+#!/usr/bin/env node
+const path = require("path");
+const fs = require("fs").promises;
+const os = require("os");
+const crypto = require("crypto");
+
+const PROJECT_ROOT_PATH = path.join(__dirname, "..");
+const getRootFilePath = (filename) => path.join(PROJECT_ROOT_PATH, filename);
+
+async function main(argv) {
+  if (argv.length !== 3) {
+    throw new Error("Incorrect number of arguments");
+  }
+
+  const stagingDirectoryPath = path.join(
+    os.tmpdir(),
+    `helmet-middleware-release-${argv[2]}-${crypto
+      .randomBytes(8)
+      .toString("hex")}`
+  );
+
+  const getSourceFilePath = (filename) =>
+    path.join(PROJECT_ROOT_PATH, "middlewares", argv[2], filename);
+  const getDistFilePath = (filename) =>
+    path.join(PROJECT_ROOT_PATH, "dist", "middlewares", argv[2], filename);
+  const getStagingFilePath = (filename) =>
+    path.join(stagingDirectoryPath, filename);
+
+  const packageFiles = require(getSourceFilePath("package-files.json"));
+
+  const packageJson = {
+    author: "Adam Baldwin <[email protected]> (https://evilpacket.net)",
+    contributors: ["Evan Hahn <[email protected]> (https://evanhahn.com)"],
+    license: "MIT",
+    homepage: "https://helmetjs.github.io/",
+    bugs: {
+      url: "https://github.com/helmetjs/helmet/issues",
+      email: "[email protected]",
+    },
+    repository: {
+      type: "git",
+      url: "git://github.com/helmetjs/helmet.git",
+    },
+    engines: {
+      node: ">=4.0.0",
+    },
+    files: ["CHANGELOG.md", "LICENSE", "README.md", ...packageFiles],
+    main: "index.js",
+    typings: "index.d.ts",
+    ...require(getSourceFilePath("package-overrides.json")),
+  };
+
+  await fs.mkdir(stagingDirectoryPath, { recursive: true, mode: 0o700 });
+  await Promise.all([
+    fs.writeFile(
+      getStagingFilePath("package.json"),
+      JSON.stringify(packageJson, null, 2)
+    ),
+    fs.copyFile(
+      getSourceFilePath("README.md"),
+      getStagingFilePath("README.md")
+    ),
+    fs.copyFile(
+      getSourceFilePath("CHANGELOG.md"),
+      getStagingFilePath("CHANGELOG.md")
+    ),
+    fs.copyFile(getRootFilePath("LICENSE"), getStagingFilePath("LICENSE")),
+    ...packageFiles.map((filename) =>
+      fs.copyFile(getDistFilePath(filename), getStagingFilePath(filename))
+    ),
+  ]);
+
+  console.log(
+    `Staged ${packageJson.name}@${packageJson.version} in ${stagingDirectoryPath}`
+  );
+}
+
+main(process.argv).catch((err) => {
+  console.error(err);
+  process.exit(1);
+});

index.ts

@@ -1,4 +1,5 @@
 import { IncomingMessage, ServerResponse } from "http";
+import xDownloadOptions from "./middlewares/x-download-options";
 import depd = require("depd");
 
 interface HelmetOptions {
@@ -130,7 +131,7 @@ helmet.expectCt = require("expect-ct");
 helmet.frameguard = require("frameguard");
 helmet.hidePoweredBy = require("hide-powered-by");
 helmet.hsts = require("hsts");
-helmet.ieNoOpen = require("ienoopen");
+helmet.ieNoOpen = xDownloadOptions;
 helmet.noSniff = require("dont-sniff-mimetype");
 helmet.permittedCrossDomainPolicies = require("helmet-crossdomain");
 helmet.referrerPolicy = require("referrer-policy");

middlewares/x-download-options/CHANGELOG.md

@@ -0,0 +1,21 @@
+# Changelog
+
+## Unreleased
+
+### Changed
+
+- Excluded more files from npm package
+
+## 1.1.0 - 2019-03-10
+
+### Added
+
+- Added TypeScript type definitions. See [#1](https://github.com/helmetjs/ienoopen/pull/1) and [helmetjs/helmet#188](https://github.com/helmetjs/helmet/issues/188)
+- Created a changelog
+
+### Changed
+
+- Updated documentation
+- Excluded some files from npm package
+
+Changes in versions 1.0.0 and below can be found in [Helmet's changelog](https://github.com/helmetjs/helmet/blob/master/CHANGELOG.md).

middlewares/x-download-options/README.md

@@ -0,0 +1,12 @@
+# X-Download-Options middleware
+
+This middleware sets the `X-Download-Options` header to `noopen` to prevent Internet Explorer users from executing downloads in your site's context.
+
+```javascript
+const ienoopen = require("ienoopen");
+app.use(ienoopen());
+```
+
+Some web applications will serve untrusted HTML for download. By default, some versions of IE will allow you to open those HTML files _in the context of your site_, which means that an untrusted HTML page could start doing bad things in the context of your pages. For more, see [this MSDN blog post](http://blogs.msdn.com/b/ie/archive/2008/07/02/ie8-security-part-v-comprehensive-protection.aspx).
+
+This is pretty obscure, fixing a small bug on IE only. No real drawbacks other than performance/bandwidth of setting the headers, though.

middlewares/x-download-options/index.ts

@@ -0,0 +1,17 @@
+import { IncomingMessage, ServerResponse } from "http";
+
+function xDownloadOptionsMiddleware(
+  _req: IncomingMessage,
+  res: ServerResponse,
+  next: () => void
+): void {
+  res.setHeader("X-Download-Options", "noopen");
+  next();
+}
+
+function xDownloadOptions() {
+  return xDownloadOptionsMiddleware;
+}
+
+module.exports = xDownloadOptions;
+export default xDownloadOptions;

middlewares/x-download-options/package-files.json

@@ -0,0 +1 @@
+["index.js", "index.d.ts"]

middlewares/x-download-options/package-overrides.json

@@ -0,0 +1,11 @@
+{
+  "name": "ienoopen",
+  "contributors": [
+    "Evan Hahn <[email protected]> (https://evanhahn.com)",
+    "Nathan Shively-Sanders <[email protected]> (https://github.com/sandersn)"
+  ],
+  "description": "Middleware to set `X-Download-Options` header for IE8 security",
+  "version": "1.1.0",
+  "keywords": ["express", "security", "x-download-options"],
+  "homepage": "https://helmetjs.github.io/docs/ienoopen/"
+}

package.json

@@ -36,7 +36,8 @@
     "LICENSE",
     "README.md",
     "SECURITY.md",
-    "dist/index.js"
+    "dist/index.js",
+    "dist/middlewares/x-download-options/index.js"
   ],
   "dependencies": {
     "depd": "2.0.0",
@@ -50,7 +51,6 @@
     "hide-powered-by": "1.1.0",
     "hpkp": "2.0.0",
     "hsts": "2.2.0",
-    "ienoopen": "1.1.0",
     "nocache": "2.1.0",
     "referrer-policy": "1.2.0",
     "x-xss-protection": "1.3.0"
@@ -79,6 +79,7 @@
     "format": "prettier --write '**/*{md,js,json,ts}'",
     "clean": "rm -rf dist",
     "build": "npm run clean && tsc",
+    "build-middleware-package": "npm run build && ./bin/build-middleware-package.js",
     "test": "jest"
   },
   "license": "MIT",

test/helpers.ts

@@ -0,0 +1,28 @@
+import { IncomingMessage, ServerResponse } from "http";
+import connect = require("connect");
+import supertest = require("supertest");
+
+interface MiddlewareFunction {
+  (req: IncomingMessage, res: ServerResponse, next: () => void): void;
+}
+
+export async function check(
+  middleware: MiddlewareFunction,
+  expectedHeaders: Readonly<{ [headerName: string]: string | null }>
+): Promise<void> {
+  const app = connect()
+    .use(middleware)
+    .use((_req: IncomingMessage, res: ServerResponse) => {
+      res.end("Hello world!");
+    });
+
+  const { header } = await supertest(app).get("/").expect(200, "Hello world!");
+
+  for (const [headerName, headerValue] of Object.entries(expectedHeaders)) {
+    if (headerValue === null) {
+      expect(header).not.toHaveProperty(headerName);
+    } else {
+      expect(header).toHaveProperty(headerName, headerValue);
+    }
+  }
+}

test/index.test.ts

@@ -3,6 +3,7 @@ import helmet = require("..");
 import { IncomingMessage, ServerResponse } from "http";
 import connect = require("connect");
 import request = require("supertest");
+import xDowloadOptions from "../middlewares/x-download-options";
 
 describe("helmet", function () {
   describe("module aliases", function () {
@@ -107,9 +108,8 @@ describe("helmet", function () {
       expect(helmet.hsts).toBe(pkg);
     });
 
-    it('aliases "ienoopen"', function () {
-      const pkg = require("ienoopen");
-      expect(helmet.ieNoOpen).toBe(pkg);
+    it("aliases the X-Download-Options middleware to helmet.ieNoOpen", () => {
+      expect(helmet.ieNoOpen.name).toBe(xDowloadOptions.name);
     });
 
     // This test will be removed in helmet@4.

test/x-download-options.test.ts

@@ -0,0 +1,10 @@
+import { check } from "./helpers";
+import xDownloadOptions from "../middlewares/x-download-options";
+
+describe("X-Download-Options middleware", () => {
+  it('sets "X-Download-Options: noopen"', async () => {
+    await check(xDownloadOptions(), {
+      "x-download-options": "noopen",
+    });
+  });
+});

tsconfig.json

@@ -1,6 +1,6 @@
 {
   "compilerOptions": {
-    "declaration": false,
+    "declaration": true,
     "esModuleInterop": true,
     "module": "commonjs",
     "noFallthroughCasesInSwitch": true,