refactor: replace isBuffer check with isUint8Array

Author: nbbeeken

src/client-side-encryption/auto_encrypter.ts

@@ -10,7 +10,7 @@ import { MongoDBResponse, type MongoDBResponseConstructor } from '../cmap/wire_p
 import { getMongoDBClientEncryption } from '../deps';
 import { MongoRuntimeError } from '../error';
 import { MongoClient, type MongoClientOptions } from '../mongo_client';
-import { MongoDBCollectionNamespace } from '../utils';
+import { isUint8Array, MongoDBCollectionNamespace } from '../utils';
 import * as cryptoCallbacks from './crypto_callbacks';
 import { MongoCryptInvalidArgumentError } from './errors';
 import { MongocryptdManager } from './mongocryptd_manager';
@@ -480,7 +480,7 @@ export class AutoEncrypter {
   ): Promise<Document> {
     const buffer = MongoDBResponse.is(response)
       ? response.toBytes()
-      : Buffer.isBuffer(response)
+      : isUint8Array(response)
       ? response
       : serialize(response, options);
 

src/utils.ts

@@ -64,6 +64,19 @@ export const ByteUtils = {
   }
 };
 
+/**
+ * Returns true if value is a Uint8Array or a Buffer
+ * @param value - any value that may be a Uint8Array
+ */
+export function isUint8Array(value: unknown): value is Uint8Array {
+  return (
+    value != null &&
+    typeof value === 'object' &&
+    Symbol.toStringTag in value &&
+    value[Symbol.toStringTag] === 'Uint8Array'
+  );
+}
+
 /**
  * Determines if a connection's address matches a user provided list
  * of domain wildcards.

test/unit/utils.test.ts

@@ -7,6 +7,7 @@ import {
   HostAddress,
   hostMatchesWildcards,
   isHello,
+  isUint8Array,
   LEGACY_HELLO_COMMAND,
   List,
   matchesParentDomain,
@@ -981,4 +982,29 @@ describe('driver utils', function () {
       });
     });
   });
+
+  describe('isUint8Array()', () => {
+    describe('when given a UintArray', () =>
+      it('returns true', () => expect(isUint8Array(Uint8Array.from([1]))).to.be.true));
+
+    describe('when given a Buffer', () =>
+      it('returns true', () => expect(isUint8Array(Buffer.from([1]))).to.be.true));
+
+    describe('when given a value that does not have `Uint8Array` at Symbol.toStringTag', () => {
+      it('returns false', () => {
+        const weirdArray = Uint8Array.from([1]);
+        Object.defineProperty(weirdArray, Symbol.toStringTag, { value: 'blah' });
+        expect(isUint8Array(weirdArray)).to.be.false;
+      });
+    });
+
+    describe('when given null', () =>
+      it('returns false', () => expect(isUint8Array(null)).to.be.false));
+
+    describe('when given a non object', () =>
+      it('returns false', () => expect(isUint8Array('')).to.be.false));
+
+    describe('when given an object that does not respond to Symbol.toStringTag', () =>
+      it('returns false', () => expect(isUint8Array(Object.create(null))).to.be.false));
+  });
 });