feat: Add createOriginMiddleware function

packages/json-rpc-engine/CHANGELOG.md

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+
+- Add `createOriginMiddleware` utility ([#8522](https://github.com/MetaMask/core/pull/8522))
+
 ## [10.2.4]
 
 ### Fixed

packages/json-rpc-engine/src/v2/createOriginMiddleware.test.ts

@@ -0,0 +1,19 @@
+import { makeRequest } from '../../tests/utils';
+import { createOriginMiddleware } from './createOriginMiddleware';
+import { JsonRpcEngineV2 } from './JsonRpcEngineV2';
+
+describe('createOriginMiddleware', () => {
+  it('sets the origin on the context object', async () => {
+    const origin = 'https://metamask.io';
+    const middleware = createOriginMiddleware(origin);
+
+    const engine = JsonRpcEngineV2.create({
+      middleware: [
+        middleware,
+        ({ context }): string => context.assertGet('origin'),
+      ],
+    });
+
+    expect(await engine.handle(makeRequest())).toBe(origin);
+  });
+});

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

@@ -0,0 +1,18 @@
+import { JsonRpcMiddleware } from './JsonRpcEngineV2';
+import { MiddlewareContext } from './MiddlewareContext';
+import { Json, JsonRpcRequest } from './utils';
+
+/**
+ * Create a middleware function that adds `origin` to the middleware context.
+ *
+ * @param origin - The origin.
+ * @returns The middleware.
+ */
+export function createOriginMiddleware<
+  Context extends MiddlewareContext<{ origin: string }>,
+>(origin: string): JsonRpcMiddleware<JsonRpcRequest, Json, Context> {
+  return ({ context, next }) => {
+    context.set('origin', origin);
+    return next();
+  };
+}

packages/json-rpc-engine/src/v2/index.test.ts

@@ -9,6 +9,7 @@ describe('@metamask/json-rpc-engine/v2', () => {
         "JsonRpcServer",
         "MiddlewareContext",
         "asLegacyMiddleware",
+        "createOriginMiddleware",
         "createScaffoldMiddleware",
         "getUniqueId",
         "isNotification",

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

@@ -1,5 +1,6 @@
 export { asLegacyMiddleware } from './asLegacyMiddleware';
 export { getUniqueId } from '../getUniqueId';
+export { createOriginMiddleware } from './createOriginMiddleware';
 export { createScaffoldMiddleware } from './createScaffoldMiddleware';
 export { JsonRpcEngineV2 } from './JsonRpcEngineV2';
 export type {