refactor(node/crypto): port polyfill to Rust for randomInt, randomFil…

…l, randomFillSync (#18658)

Pretty much as per the title, I'd welcome some feedback especially
around the
array/buffer handling in the two randomFill functions.

cli/tests/unit_node/internal/_randomFill_test.ts

@@ -6,6 +6,7 @@ import {
   assertNotEquals,
   assertThrows,
 } from "../../../../test_util/std/testing/asserts.ts";
+import { deferred } from "../../../../test_util/std/async/deferred.ts";
 
 const validateNonZero = (buf: Buffer) => {
   if (!buf.some((ch) => ch > 0)) throw new Error("Error");
@@ -15,14 +16,18 @@ const validateZero = (buf: Buffer) => {
   buf.forEach((val) => assertEquals(val, 0));
 };
 
-Deno.test("[node/crypto.randomFill]", () => {
+Deno.test("[node/crypto.randomFill]", async () => {
+  const promise = deferred();
   const buf = Buffer.alloc(10);
   const before = buf.toString("hex");
 
   randomFill(buf, 5, 5, (_err, bufTwo) => {
     const after = bufTwo?.toString("hex");
     assertEquals(before.slice(0, 10), after?.slice(0, 10));
+    promise.resolve(true);
   });
+
+  await promise;
 });
 
 Deno.test("[node/crypto.randomFillSync]", () => {

ext/node/crypto/mod.rs

@@ -9,6 +9,8 @@ use deno_core::StringOrBuffer;
 use deno_core::ZeroCopyBuf;
 use hkdf::Hkdf;
 use num_bigint::BigInt;
+use rand::distributions::Distribution;
+use rand::distributions::Uniform;
 use rand::Rng;
 use std::future::Future;
 use std::rc::Rc;
@@ -478,3 +480,13 @@ pub async fn op_node_hkdf_async(
   })
   .await?
 }
+
+#[op]
+pub fn op_node_random_int(min: i32, max: i32) -> Result<i32, AnyError> {
+  let mut rng = rand::thread_rng();
+  // Uniform distribution is required to avoid Modulo Bias
+  // https://en.wikipedia.org/wiki/Fisher–Yates_shuffle#Modulo_bias
+  let dist = Uniform::from(min..max);
+
+  Ok(dist.sample(&mut rng))
+}

ext/node/lib.rs

@@ -194,6 +194,7 @@ deno_core::extension!(deno_node,
     crypto::op_node_generate_secret,
     crypto::op_node_generate_secret_async,
     crypto::op_node_sign,
+    crypto::op_node_random_int,
     crypto::x509::op_node_x509_parse,
     crypto::x509::op_node_x509_ca,
     crypto::x509::op_node_x509_check_email,

ext/node/polyfills/internal/crypto/_randomFill.ts

@@ -1,8 +1,10 @@
 // Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
-import randomBytes, {
+import {
   MAX_SIZE as kMaxUint32,
 } from "ext:deno_node/internal/crypto/_randomBytes.ts";
 import { Buffer } from "ext:deno_node/buffer.ts";
+const { core } = globalThis.__bootstrap;
+const { ops } = core;
 
 const kBufferMaxLength = 0x7fffffff;
 
@@ -62,11 +64,14 @@ export default function randomFill(
   assertOffset(offset as number, buf.length);
   assertSize(size as number, offset as number, buf.length);
 
-  randomBytes(size as number, (err, bytes) => {
-    if (err) return cb!(err, buf);
-    bytes?.copy(buf, offset as number);
-    cb!(null, buf);
-  });
+  core.opAsync("op_node_generate_secret_async", Math.floor(size as number))
+    .then(
+      (randomData: Uint8Array) => {
+        const randomBuf = Buffer.from(randomData.buffer);
+        randomBuf.copy(buf, offset as number, 0, size as number);
+        cb!(null, buf);
+      },
+    );
 }
 
 export function randomFillSync(buf: Buffer, offset = 0, size?: number) {
@@ -76,9 +81,10 @@ export function randomFillSync(buf: Buffer, offset = 0, size?: number) {
 
   assertSize(size, offset, buf.length);
 
-  const bytes = randomBytes(size);
-
-  bytes.copy(buf, offset);
+  const bytes: Uint8Array = new Uint8Array(Math.floor(size));
+  ops.op_node_generate_secret(bytes);
+  const bytesBuf: Buffer = Buffer.from(bytes.buffer);
+  bytesBuf.copy(buf, offset, 0, size);
 
   return buf;
 }

ext/node/polyfills/internal/crypto/_randomInt.ts

@@ -1,4 +1,6 @@
 // Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
+const ops = globalThis.Deno.core.ops;
+
 export default function randomInt(max: number): number;
 export default function randomInt(min: number, max: number): number;
 export default function randomInt(
@@ -40,16 +42,9 @@ export default function randomInt(
     throw new Error("Min is bigger than Max!");
   }
 
-  const randomBuffer = new Uint32Array(1);
-
-  globalThis.crypto.getRandomValues(randomBuffer);
-
-  const randomNumber = randomBuffer[0] / (0xffffffff + 1);
-
   min = Math.ceil(min);
   max = Math.floor(max);
-
-  const result = Math.floor(randomNumber * (max - min)) + min;
+  const result = ops.op_node_random_int(min, max);
 
   if (cb) {
     cb(null, result);