feat: implement message size validation to prevent excessive payloads

packages/sdk/src/config.ts

@@ -73,3 +73,5 @@ export const EXTENSION_EVENTS = {
   CONNECT: 'connect',
   CONNECTED: 'connected',
 };
+
+export const MAX_MESSAGE_LENGTH = 1_000_000; // 1MB limit

packages/sdk/src/services/MobilePortStream/write.test.ts

@@ -1,4 +1,5 @@
 import { Buffer } from 'buffer';
+import { MAX_MESSAGE_LENGTH } from '../../config';
 import { write } from './write';
 
 describe('write function', () => {
@@ -77,4 +78,50 @@ describe('write function', () => {
       new Error('MobilePortStream - disconnected'),
     );
   });
+
+  describe('Message Size Validation', () => {
+    beforeEach(() => {
+      jest.clearAllMocks();
+      global.window = {
+        location: { href: 'http://example.com' },
+        ReactNativeWebView: { postMessage: mockPostMessage },
+      } as any;
+    });
+
+    it('should reject messages exceeding MAX_MESSAGE_LENGTH', () => {
+      const largeData = {
+        data: {
+          jsonrpc: '2.0',
+          method: 'test_method',
+          params: ['x'.repeat(MAX_MESSAGE_LENGTH)],
+        },
+      };
+
+      write(largeData, 'utf-8', cb);
+
+      expect(cb).toHaveBeenCalledWith(
+        expect.objectContaining({
+          message: expect.stringMatching(
+            /Message size \d+ exceeds maximum allowed size of \d+ bytes/u,
+          ),
+        }),
+      );
+      expect(mockPostMessage).not.toHaveBeenCalled();
+    });
+
+    it('should accept messages within MAX_MESSAGE_LENGTH', () => {
+      const validData = {
+        data: {
+          jsonrpc: '2.0',
+          method: 'test_method',
+          params: ['x'.repeat(100)],
+        },
+      };
+
+      write(validData, 'utf-8', cb);
+
+      expect(cb).toHaveBeenCalledWith();
+      expect(mockPostMessage).toHaveBeenCalled();
+    });
+  });
 });

packages/sdk/src/services/MobilePortStream/write.ts

@@ -1,4 +1,5 @@
 import { Buffer } from 'buffer';
+import { MAX_MESSAGE_LENGTH } from '../../config';
 
 /**
  * Handles communication between the in-app browser and MetaMask mobile application.
@@ -15,6 +16,7 @@ export function write(
   cb: (error?: Error | null) => void,
 ) {
   try {
+    let stringifiedData: string;
     if (Buffer.isBuffer(chunk)) {
       const data: {
         type: 'Buffer';
@@ -23,18 +25,30 @@ export function write(
       } = chunk.toJSON();
 
       data._isBuffer = true;
-      window.ReactNativeWebView?.postMessage(
-        JSON.stringify({ ...data, origin: window.location.href }),
-      );
+      stringifiedData = JSON.stringify({
+        ...data,
+        origin: window.location.href,
+      });
     } else {
       if (chunk.data) {
         chunk.data.toNative = true;
       }
 
-      window.ReactNativeWebView?.postMessage(
-        JSON.stringify({ ...chunk, origin: window.location.href }),
+      stringifiedData = JSON.stringify({
+        ...chunk,
+        origin: window.location.href,
+      });
+    }
+
+    if (stringifiedData.length > MAX_MESSAGE_LENGTH) {
+      return cb(
+        new Error(
+          `Message size ${stringifiedData.length} exceeds maximum allowed size of ${MAX_MESSAGE_LENGTH} bytes`,
+        ),
       );
     }
+
+    window.ReactNativeWebView?.postMessage(stringifiedData);
   } catch (err) {
     return cb(new Error('MobilePortStream - disconnected'));
   }

packages/sdk/src/services/RemoteCommunicationPostMessageStream/write.test.ts

@@ -1,9 +1,9 @@
-import { Ethereum } from '../Ethereum'; // Adjust the import based on your project structure
 import { RemoteCommunicationPostMessageStream } from '../../PostMessageStream/RemoteCommunicationPostMessageStream'; // Adjust the import based on your project structure
-import { METHODS_TO_REDIRECT } from '../../config';
+import { MAX_MESSAGE_LENGTH, METHODS_TO_REDIRECT } from '../../config';
 import * as loggerModule from '../../utils/logger'; // Adjust the import based on your project structure
-import { write } from './write'; // Adjust the import based on your project structure
+import { Ethereum } from '../Ethereum'; // Adjust the import based on your project structure
 import { extractMethod } from './extractMethod';
+import { write } from './write'; // Adjust the import based on your project structure
 
 jest.mock('./extractMethod');
 jest.mock('../Ethereum');
@@ -162,11 +162,22 @@ describe('write function', () => {
       mockIsMobileWeb.mockReturnValue(false);
       mockIsSecure.mockReturnValue(true);
       mockGetChannelId.mockReturnValue('some_channel_id');
+      mockIsMetaMaskInstalled.mockReturnValue(true);
+      mockGetKeyInfo.mockReturnValue({ ecies: { public: 'test_public_key' } });
+      mockHasDeeplinkProtocol.mockReturnValue(false);
     });
 
     it('should redirect if method exists in METHODS_TO_REDIRECT', async () => {
       mockExtractMethod.mockReturnValue({
         method: Object.keys(METHODS_TO_REDIRECT)[0],
+        data: {
+          data: {
+            jsonrpc: '2.0',
+            method: Object.keys(METHODS_TO_REDIRECT)[0],
+            params: [],
+          },
+        },
+        triggeredInstaller: false,
       });
 
       await write(
@@ -239,4 +250,71 @@ describe('write function', () => {
       expect(spyLogger).toHaveBeenCalled();
     });
   });
+
+  describe('Message Size Validation', () => {
+    it('should reject messages exceeding MAX_MESSAGE_LENGTH', async () => {
+      mockGetChannelId.mockReturnValue('some_channel_id');
+      mockIsReady.mockReturnValue(true);
+      mockIsConnected.mockReturnValue(true);
+
+      // Mock extractMethod to return large data
+      const largeData = {
+        jsonrpc: '2.0',
+        method: 'eth_call',
+        params: ['x'.repeat(MAX_MESSAGE_LENGTH + 1)],
+      };
+
+      mockExtractMethod.mockReturnValue({
+        method: 'eth_call',
+        data: {
+          data: largeData,
+        },
+      });
+
+      await write(
+        mockRemoteCommunicationPostMessageStream,
+        { jsonrpc: '2.0', method: 'eth_call' },
+        'utf8',
+        callback,
+      );
+
+      // Don't test for exact error message, just verify it contains the key parts
+      expect(callback).toHaveBeenCalledWith(
+        expect.objectContaining({
+          message: expect.stringMatching(
+            /Message size \d+ exceeds maximum allowed size of \d+ bytes/u,
+          ),
+        }),
+      );
+      expect(mockSendMessage).not.toHaveBeenCalled();
+    });
+
+    it('should accept messages within MAX_MESSAGE_LENGTH', async () => {
+      mockGetChannelId.mockReturnValue('some_channel_id');
+      mockIsReady.mockReturnValue(true);
+      mockIsConnected.mockReturnValue(true);
+
+      // Mock extractMethod to return valid-sized data
+      mockExtractMethod.mockReturnValue({
+        method: 'eth_call',
+        data: {
+          data: {
+            jsonrpc: '2.0',
+            method: 'eth_call',
+            params: ['x'.repeat(100)],
+          },
+        },
+      });
+
+      await write(
+        mockRemoteCommunicationPostMessageStream,
+        { jsonrpc: '2.0', method: 'eth_call' },
+        'utf8',
+        callback,
+      );
+
+      expect(callback).toHaveBeenCalledWith();
+      expect(mockSendMessage).toHaveBeenCalled();
+    });
+  });
 });

packages/sdk/src/services/RemoteCommunicationPostMessageStream/write.ts

@@ -1,5 +1,9 @@
 import { RemoteCommunicationPostMessageStream } from '../../PostMessageStream/RemoteCommunicationPostMessageStream';
-import { METHODS_TO_REDIRECT, RPC_METHODS } from '../../config';
+import {
+  METHODS_TO_REDIRECT,
+  RPC_METHODS,
+  MAX_MESSAGE_LENGTH,
+} from '../../config';
 import {
   METAMASK_CONNECT_BASE_URL,
   METAMASK_DEEPLINK_BASE,
@@ -57,11 +61,17 @@ export async function write(
     deeplinkProtocolAvailable && mobileWeb && authorized;
 
   try {
-    console.warn(
-      `[RCPMS: _write()] triggeredInstaller=${triggeredInstaller} activeDeeplinkProtocol=${activeDeeplinkProtocol}`,
-    );
-
     if (!triggeredInstaller) {
+      // Check message size before sending
+      const stringifiedData = JSON.stringify(data?.data);
+      if (stringifiedData.length > MAX_MESSAGE_LENGTH) {
+        return callback(
+          new Error(
+            `Message size ${stringifiedData.length} exceeds maximum allowed size of ${MAX_MESSAGE_LENGTH} bytes`,
+          ),
+        );
+      }
+
       // The only reason not to send via network is because the rpc call will be sent in the deeplink
       instance.state.remote
         ?.sendMessage(data?.data)