npm package discovery and stats viewer.

Discover Tips

  • General search

    [free text search, go nuts!]

  • Package details

    pkg:[package-name]

  • User packages

    @[username]

Sponsor

Optimize Toolset

I’ve always been into building performant and accessible sites, but lately I’ve been taking it extremely seriously. So much so that I’ve been building a tool to help me optimize and monitor the sites that I build to make sure that I’m making an attempt to offer the best experience to those who visit them. If you’re into performant, accessible and SEO friendly sites, you might like it too! You can check it out at Optimize Toolset.

About

Hi, 👋, I’m Ryan Hefner  and I built this site for me, and you! The goal of this site was to provide an easy way for me to check the stats on my npm packages, both for prioritizing issues and updates, and to give me a little kick in the pants to keep up on stuff.

As I was building it, I realized that I was actually using the tool to build the tool, and figured I might as well put this out there and hopefully others will find it to be a fast and useful way to search and browse npm packages as I have.

If you’re interested in other things I’m working on, follow me on Twitter or check out the open source projects I’ve been publishing on GitHub.

I am also working on a Twitter bot for this site to tweet the most popular, newest, random packages from npm. Please follow that account now and it will start sending out packages soon–ish.

Open Software & Tools

This site wouldn’t be possible without the immense generosity and tireless efforts from the people who make contributions to the world and share their work via open source initiatives. Thank you 🙏

© 2024 – Pkg Stats / Ryan Hefner

express-header-blocker

v1.1.0

Published

Prohibit access for the particular header orders with auto training

Downloads

3

Readme

express-header-blocker

A library that provides middleware to block requests based on the order of certain headers

Installation

npm install express-header-blocker

Usage

Import the middleware

const headerBlocker = require("express-header-blocker");

Apply the middleware to specific routes or globally to all routes

// Apply globally to all routes
app.use(headerOrderBlockerMiddleware());

// Apply to specific routes
app.post('/secure-route', headerOrderBlockerMiddleware(), (req, res) => {
    ...
});

Options

The middleware accepts an options object with the following properties:

  • isModelLearningEnabled: A boolean value that determines whether the middleware should enable model learning. When enabled, the middleware will learn and block new header orders that are not explicitly defined in the onlyAnalyzeHeaders configuration but can be swapped to the memento. (Default: false)

  • onlyAnalyzeHeaders: An array of header names (case-insensitive) that should be analyzed by the middleware. If provided, only the specified headers will be considered for header order analysis. (Default: [] - meaning all headers will be considered)

  • sensitivity: An integer that sets the sensitivity level of the header order analysis. The sensitivity determines how tolerant the middleware should be towards different header orders. Higher values make the middleware more permissive. (Default: 2)

Configure the middleware when applying it if needed

const options = {
  isModelLearningEnabled: true,
  onlyAnalyzeHeaders: ["user-agent", "content-type"],
  sensitivity: 3,
};

app.use(headerOrderBlockerMiddleware(options));

Blocking Header Orders

The middleware maintains a collection of blocked header orders. If a request's header order matches a blocked order or can be transformed into a blocked order within the specified sensitivity level, the request will be blocked.

To block a specific header order manually, you can use the req.block() method within the route handler:

app.post("/block-custom-order", (req, res) => {
  req.block();

  res.send("request is blocked due to a custom order");
});

Examples

  1. Blocking Specific Header Order
const options = {
  onlyAnalyzeHeaders: ["authorization", "user-agent"],
  sensitivity: 2,
};

app.use(headerOrderBlockerMiddleware(options));

The middleware will only analyze the 'Authorization' and 'User-Agent' headers for order anomalies and block requests that match a blocked order within a sensitivity of 2.

  1. Enabling Model Learning
const options = {
  isModelLearningEnabled: true,
  onlyAnalyzeHeaders: ["accept", "content-type"],
};

app.use(headerOrderBlockerMiddleware(options));

With model learning enabled, the middleware will start learning from blocked headers, and if it encounters a new header order that requires blocking, it will add it to the blocked headers collection.

Full example

const express = require("express");

const headerBlocker = require("express-header-blocker");

const PORT = 3000;

const app = express();

app.use(
  headerBlocker({
    isModelLearningEnabled: false,
    onlyAnalyzeHeaders: [
      "host",
      "accept",
      "user-agent",
      "accept-encoding",
      "accept-language",
    ],
  })
);

app.use("/", (req, res, next) => {
  if (req.blocked) {
    return res.send("blocked");
  }

  next();
});

app.get("/", (_, res) => {
  res.send(
    `<form method="post" action="/block"><button type="submit">Block me</button></form>`
  );
});

app.post("/block", (req, res) => {
  req.block();

  return res.send("you are now blocked");
});

app.listen(PORT);