Add uuid generation functions that uses high quality RNG.

vendor/uuid/rng.js

@@ -0,0 +1,44 @@
+/*
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ *
+ * Copyright (c) 2016 Andrey Antukh <niwi@niwi.nz>
+*/
+
+"use strict";
+
+goog.provide("uuid.rng");
+
+goog.scope(function() {
+  uuid.rng.getBytes = null;
+
+  // Check if nodejs rng is available (high quality);
+  if (goog.global.require !== undefined) {
+    const crypto = goog.global.require("crypto");
+
+    uuid.rng.getBytes = function(n) {
+      return crypto.randomBytes(n);
+    };
+  }
+  // Check if whatwg rng is available (high quality);
+  else if (goog.global.crypto.getRandomValues !== undefined) {
+    uuid.rng.getBytes = function(n) {
+      const buf = new Uint8Array(16);
+      goog.global.crypto.getRandomValues(buf);
+      return buf;
+    };
+  }
+  // Switch Back to the Math.random (low quality);
+  else {
+    console.warn("No high quality RNG available, switching back to Math.random.");
+    uuid.rng.getBytes = function(n) {
+      const buf = new Array(16);
+      for (let i = 0, r; i < 16; i++) {
+        if ((i & 0x03) === 0) { r = Math.random() * 0x100000000; }
+        buf[i] = r >>> ((i & 0x03) << 3) & 0xff;
+      }
+      return buf;
+    };
+  }
+});