node-postgres/packages/pg/lib/stream.js

const { getStream, getSecureStream } = getStreamFuncs()

module.exports = {
  /**
   * Get a socket stream compatible with the current runtime environment.
   * @returns {Duplex}
   */
  getStream,
  /**
   * Get a TLS secured socket, compatible with the current environment,
   * using the socket and other settings given in `options`.
   * @returns {Duplex}
   */
  getSecureStream,
}

/**
 * The stream functions that work in Node.js
 */
function getNodejsStreamFuncs() {
  function getStream(ssl) {
    const net = require('net')
    return new net.Socket()
  }

  function getSecureStream(options) {
    var tls = require('tls')
    return tls.connect(options)
  }
  return {
    getStream,
    getSecureStream,
  }
}

/**
 * The stream functions that work in Cloudflare Workers
 */
function getCloudflareStreamFuncs() {
  function getStream(ssl) {
    const { CloudflareSocket } = require('pg-cloudflare')
    return new CloudflareSocket(ssl)
  }

  function getSecureStream(options) {
    options.socket.startTls(options)
    return options.socket
  }
  return {
    getStream,
    getSecureStream,
  }
}

/**
 * Are we running in a Cloudflare Worker?
 *
 * @returns true if the code is currently running inside a Cloudflare Worker.
 */
function isCloudflareRuntime() {
  // Since 2022-03-21 the `global_navigator` compatibility flag is on for Cloudflare Workers
  // which means that `navigator.userAgent` will be defined.
  if (typeof navigator === 'object' && navigator !== null && typeof navigator.userAgent === 'string') {
    return navigator.userAgent === 'Cloudflare-Workers'
  }
  // In case `navigator` or `navigator.userAgent` is not defined then try a more sneaky approach
  if (typeof Response === 'function') {
    const resp = new Response(null, { cf: { thing: true } })
    if (typeof resp.cf === 'object' && resp.cf !== null && resp.cf.thing) {
      return true
    }
  }
  return false
}

function getStreamFuncs() {
  if (isCloudflareRuntime()) {
    return getCloudflareStreamFuncs()
  }
  return getNodejsStreamFuncs()
}