1 files changed, 84 insertions, 0 deletions
diff --git a/ext/node/polyfills/internal/crypto/_randomFill.ts b/ext/node/polyfills/internal/crypto/_randomFill.ts
new file mode 100644
index 000000000..045072696
--- /dev/null
+++ b/ext/node/polyfills/internal/crypto/_randomFill.ts
@@ -0,0 +1,84 @@
+// Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
+import randomBytes, {
+  MAX_SIZE as kMaxUint32,
+} from "internal:deno_node/polyfills/internal/crypto/_randomBytes.ts";
+import { Buffer } from "internal:deno_node/polyfills/buffer.ts";
+
+const kBufferMaxLength = 0x7fffffff;
+
+function assertOffset(offset: number, length: number) {
+  if (offset > kMaxUint32 || offset < 0) {
+    throw new TypeError("offset must be a uint32");
+  }
+
+  if (offset > kBufferMaxLength || offset > length) {
+    throw new RangeError("offset out of range");
+  }
+}
+
+function assertSize(size: number, offset: number, length: number) {
+  if (size > kMaxUint32 || size < 0) {
+    throw new TypeError("size must be a uint32");
+  }
+
+  if (size + offset > length || size > kBufferMaxLength) {
+    throw new RangeError("buffer too small");
+  }
+}
+
+export default function randomFill(
+  buf: Buffer,
+  cb: (err: Error | null, buf: Buffer) => void,
+): void;
+
+export default function randomFill(
+  buf: Buffer,
+  offset: number,
+  cb: (err: Error | null, buf: Buffer) => void,
+): void;
+
+export default function randomFill(
+  buf: Buffer,
+  offset: number,
+  size: number,
+  cb: (err: Error | null, buf: Buffer) => void,
+): void;
+
+export default function randomFill(
+  buf: Buffer,
+  offset?: number | ((err: Error | null, buf: Buffer) => void),
+  size?: number | ((err: Error | null, buf: Buffer) => void),
+  cb?: (err: Error | null, buf: Buffer) => void,
+) {
+  if (typeof offset === "function") {
+    cb = offset;
+    offset = 0;
+    size = buf.length;
+  } else if (typeof size === "function") {
+    cb = size;
+    size = buf.length - Number(offset as number);
+  }
+
+  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);
+  });
+}
+
+export function randomFillSync(buf: Buffer, offset = 0, size?: number) {
+  assertOffset(offset, buf.length);
+
+  if (size === undefined) size = buf.length - offset;
+
+  assertSize(size, offset, buf.length);
+
+  const bytes = randomBytes(size);
+
+  bytes.copy(buf, offset);
+
+  return buf;
+}