@small-tech/auto-encrypt/lib/staging/monkeyPatchTls.js

Automatically provisions and renews Let’s Encrypt TLS certificates on Node.js https servers (including Kitten, Polka, Express.js, etc.)

/**
 * Monkey patches the TLS module to accept run-time root and intermediary Certificate Authority (CA) certificates.
 *
 * Based on the method provided by David Barral at https://link.medium.com/6xHYLeUVq5.
 *
 * @module
 * @copyright Copyright © 2020 Aral Balkan, Small Technology Foundation.
 * @license AGPLv3 or later.
 */
import fs from 'fs'
import tls from 'tls'
import path from 'path'
import { fileURLToPath } from 'url'

const __dirname = fileURLToPath(new URL('.', import.meta.url))

/**
 * Monkey patches the TLS module to accept the Let’s Encrypt staging certificate.
 *
 * @alias module:lib/MonkeyPatchTls
 */
export default function monkeyPatchTLS () {
  const originalCreateSecureContext = tls.createSecureContext

  let pem = fs
  .readFileSync(path.join(__dirname, 'fakelerootx1.pem'), { encoding: 'ascii' })
  .replace(/\r\n/g, "\n")

  const certificates = pem.match(/-----BEGIN CERTIFICATE-----\n[\s\S]+?\n-----END CERTIFICATE-----/g)

  tls.createSecureContext = options => {
    const context = originalCreateSecureContext(options)

    certificates.forEach(certificate => {
      context.context.addCACert(certificate.trim())
    })

    return context
  }
}