refactor: tighten up cloudflare detection

packages/pg/lib/stream.js

@@ -1,28 +1,81 @@
+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,
+}
+
 /**
- * Get a socket stream compatible with the current runtime environment.
- * @returns {Duplex}
+ * The stream functions that work in Node.js
  */
-module.exports.getStream = function getStream(ssl) {
-  const net = require('net')
-  if (typeof net.Socket === 'function') {
+function getNodejsStreamFuncs() {
+  function getStream(ssl) {
+    const net = require('net')
     return new net.Socket()
-  } else {
-    const { CloudflareSocket } = require('pg-cloudflare')
-    return new CloudflareSocket(ssl)
+  }
+
+  function getSecureStream(options) {
+    var tls = require('tls')
+    return tls.connect(options)
+  }
+  return {
+    getStream,
+    getSecureStream,
   }
 }
 
 /**
- * Get a TLS secured socket, compatible with the current environment,
- * using the socket and other settings given in `options`.
- * @returns {Duplex}
+ * The stream functions that work in Cloudflare Workers
  */
-module.exports.getSecureStream = function getSecureStream(options) {
-  var tls = require('tls')
-  if (tls.connect) {
-    return tls.connect(options)
-  } else {
+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()
 }