refactor: Replace rfdc with klona

Author: rekmarks

packages/json-rpc-engine/package.json

@@ -72,7 +72,7 @@
     "@metamask/utils": "^11.8.1",
     "@types/deep-freeze-strict": "^1.1.0",
     "deep-freeze-strict": "^1.1.1",
-    "rfdc": "^1.4.1"
+    "klona": "^2.0.6"
   },
   "devDependencies": {
     "@lavamoat/allow-scripts": "^3.0.4",

packages/json-rpc-engine/src/v2/asLegacyMiddleware.ts

@@ -43,7 +43,8 @@ export function asLegacyMiddleware<
     propagateToRequest(req, context);
 
     if (result !== undefined) {
-      res.result = deepClone(result) as ResultConstraint<Request>;
+      // Unclear why the `as unknown` is needed here, but the cast is safe.
+      res.result = deepClone(result) as unknown as ResultConstraint<Request>;
       return undefined;
     }
     return next();

packages/json-rpc-engine/src/v2/compatibility-utils.test.ts

@@ -28,6 +28,43 @@ describe('compatibility-utils', () => {
       expect(clonedRequest).toStrictEqual(request);
       expect(clonedRequest).not.toBe(request);
     });
+
+    it('produces a mutable clone of a frozen object', () => {
+      const request = Object.freeze({
+        jsonrpc,
+        method: 'test_method' as string,
+        params: Object.freeze([1, 2, 3]),
+        id: 1,
+      });
+
+      const clonedRequest = deepClone(request);
+
+      expect(clonedRequest).toStrictEqual(request);
+      expect(clonedRequest).not.toBe(request);
+      expect(Object.isFrozen(clonedRequest)).toBe(false);
+      expect(Object.isFrozen(clonedRequest.params)).toBe(false);
+
+      clonedRequest.method = 'modified_method';
+      clonedRequest.params[1] = 42;
+
+      expect(request.method).toBe('test_method');
+      expect(clonedRequest.params[1]).toBe(42);
+    });
+
+    it('ignores symbol properties', () => {
+      const symbolProp = Symbol('test');
+      const request = {
+        jsonrpc,
+        method: 'test_method' as string,
+        params: [1, 2, 3],
+        id: 1,
+        [symbolProp]: 'value',
+      };
+
+      const clonedRequest = deepClone(request);
+      // @ts-expect-error - Symbol properties are omitted
+      expect(clonedRequest[symbolProp]).toBeUndefined();
+    });
   });
 
   describe('fromLegacyRequest', () => {

packages/json-rpc-engine/src/v2/compatibility-utils.ts

@@ -1,24 +1,36 @@
 import { getMessageFromCode, JsonRpcError } from '@metamask/rpc-errors';
 import type { Json } from '@metamask/utils';
 import { hasProperty, isObject } from '@metamask/utils';
-import rfdc from 'rfdc';
+// ATTN: We must NOT use 'klona/full' here because it freezes properties on the clone.
+import { klona } from 'klona';
 
 import { MiddlewareContext } from './MiddlewareContext';
 import { stringify, type JsonRpcRequest } from './utils';
 
 // Legacy engine compatibility utils
 
 /**
- * Create a deep clone of a value. Assumes acyclical objects. Ignores the
- * prototype chain.
+ * Create a deep clone of a value as follows:
+ * - Assumes acyclical objects
+ * - Does not copy property descriptors (i.e. uses mutable defaults)
+ * - Ignores non-enumerable properties
+ * - Ignores getters and setters
  *
+ * @throws If the value is an object with a circular reference.
  * @param value - The value to clone.
  * @returns The cloned value.
  */
-export const deepClone = rfdc({
-  circles: false,
-  proto: false,
-});
+export const deepClone = <T>(value: T): DeepCloned<T> =>
+  klona(value) as DeepCloned<T>;
+
+// Matching the default implementation of klona, this type:
+// - Removes readonly modifiers
+// - Excludes non-enumerable / symbol properties
+type DeepCloned<T> = T extends readonly (infer U)[]
+  ? DeepCloned<U>[]
+  : T extends object
+    ? { -readonly [K in keyof T & (string | number)]: DeepCloned<T[K]> }
+    : T;
 
 /**
  * Standard JSON-RPC request properties.

yarn.lock

@@ -3833,7 +3833,7 @@ __metadata:
     deepmerge: "npm:^4.2.2"
     jest: "npm:^27.5.1"
     jest-it-up: "npm:^2.0.2"
-    rfdc: "npm:^1.4.1"
+    klona: "npm:^2.0.6"
     ts-jest: "npm:^27.1.4"
     typedoc: "npm:^0.24.8"
     typescript: "npm:~5.2.2"
@@ -13794,7 +13794,7 @@ __metadata:
   languageName: node
   linkType: hard
 
-"rfdc@npm:^1.3.0, rfdc@npm:^1.4.1":
+"rfdc@npm:^1.3.0":
   version: 1.4.1
   resolution: "rfdc@npm:1.4.1"
   checksum: 10/2f3d11d3d8929b4bfeefc9acb03aae90f971401de0add5ae6c5e38fec14f0405e6a4aad8fdb76344bfdd20c5193110e3750cbbd28ba86d73729d222b6cf4a729