Proxy middleware for Nuxt framework. (usage in the comment)

hash.js

import crypto from 'crypto';

export function randomHex(length) {
  return crypto.randomBytes(length / 2).toString('hex');
}

export function createHash(url, secretKey) {
  const randomHexStr = randomHex(64); 
  const timestamp = Date.now(); 

  const hmacPayload = `${randomHexStr}:${url}:${timestamp}`;
  const hmac = crypto.createHmac('sha256', secretKey).update(hmacPayload).digest('hex');

  return `${randomHexStr}:${timestamp}:${hmac}`;
}

export function verifyHash(hash, url, secretKey) {
  const [randomHexStr, timestamp, hmac] = hash.split(':');

  if (!randomHexStr || !timestamp || !hmac) {
    console.error('Invalid hash structure');
    return false;
  }

  // Validate timestamp (e.g., within 5 minutes)
  const timeDifference = Date.now() - parseInt(timestamp, 10);
  const maxAllowedTime = 5 * 60 * 1000; // 5 minutes in milliseconds
  if (timeDifference > maxAllowedTime) {
    console.error('Hash expired');
    return false;
  }

  // Recompute the HMAC
  const hmacPayload = `${randomHexStr}:${url}:${timestamp}`;
  const expectedHmac = crypto.createHmac('sha256', secretKey).update(hmacPayload).digest('hex');

  // Validate HMAC
  if (expectedHmac !== hmac) {
    console.error('HMAC mismatch');
    return false;
  }

  return true;
}

proxy.js

import HttpProxy from 'http-proxy';
import { createHash } from '~/utils/hash';

const proxy = new HttpProxy();

export default fromNodeMiddleware((req, res, next) => {
  const { apiTarget: API_TARGET, secretKey: SECRET_KEY, useVerifyHash } = useRuntimeConfig();
  
  if (req.url.startsWith('/api')) {
    proxy.web(
        req,
        res,
        {
          target: API_TARGET,
        },
        next,
    );

    proxy.on('proxyReq', (proxyReq, req, res) => {
      if (useVerifyHash) {
        const hash = createHash(req.url, SECRET_KEY);
        proxyReq.setHeader('x-verify-hash', hash)
      }
    })
  }


  else next()
})

Install

npm install http-proxy

Usage

Create the following files in your project:
middleware/proxy.js
utils/hash.js

Add the following config to your nuxt.config

runtimeConfig: {
    apiTarget: process.env.API_TARGET || 'http://localhost:4000',
    useVerifyHash: true,
    secretKey: process.env.SECRET_KEY || 'abcdef-123456'
  },

  serverMiddleware: [
    { path: '/api', handler: '~/middleware/proxy.js' },
  ],

Middleware config

apiTarget: Your main endpoint
useVerifyHash: If set to true, proxy will add a hash to the header of each proxy request then in the target server you can check if the verifyHash value In the header, is correct or not.
secretKey: a key is used for hashing

If you use the verifyHash, REMOVE the verifyHash function from your front-end project