Add crypto.getRandomValues() (#2327)

js/get_random_values.ts

@@ -0,0 +1,35 @@
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+import * as msg from "gen/cli/msg_generated";
+import * as flatbuffers from "./flatbuffers";
+import * as dispatch from "./dispatch";
+import { assert } from "./util";
+
+function req(
+  typedArray: ArrayBufferView
+): [flatbuffers.Builder, msg.Any, flatbuffers.Offset, ArrayBufferView] {
+  const builder = flatbuffers.createBuilder();
+  const inner = msg.GetRandomValues.createGetRandomValues(builder);
+  return [builder, msg.Any.GetRandomValues, inner, typedArray];
+}
+
+/** Synchronously collects cryptographically secure random values. The
+ * underlying CSPRNG in use is Rust's `rand::rngs::ThreadRng`.
+ *
+ *       const arr = new Uint8Array(32);
+ *       crypto.getRandomValues(arr);
+ */
+export function getRandomValues<
+  T extends
+    | Int8Array
+    | Uint8Array
+    | Uint8ClampedArray
+    | Int16Array
+    | Uint16Array
+    | Int32Array
+    | Uint32Array
+>(typedArray: T): T {
+  assert(typedArray !== null, "Input must not be null");
+  assert(typedArray.length <= 65536, "Input must not be longer than 65536");
+  dispatch.sendSync(...req(typedArray as ArrayBufferView));
+  return typedArray;
+}