feat(metrics): add eth-chainlist domain check to isPublicEndpointUrl cp-13.17.0 (#39623)

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## **Description**

Add eth-chainlist domain checking to isPublicEndpointUrl to improve
coverage for identifying public RPC endpoints in metrics. If a domain is
defined in eth-chainlist (cached), it's considered public and safe to
report.

Initialization only happens in background context to avoid ~300KB memory
footprint in UI.

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## **Changelog**

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CHANGELOG entry: null

## **Related issues**

Fixes: https://consensyssoftware.atlassian.net/browse/WPC-354

## **Manual testing steps**

```gherkin
Feature: RPC domain analytics

  Scenario: Verify rpc_domain shows actual host when switching to public RPC via banner
    # Setup - Add Ink network with local RPC
    Given user navigates to Settings → Networks → Add Network
    And user adds Ink network (Chain ID: 57073) with local RPC endpoint: http://127.0.0.1:8545
    And user also adds public RPC endpoint: https://rpc-qnd.inkonchain.com
    And user sets the local RPC as the default endpoint
    And user switches to Ink network
    
    # Trigger degraded state
    When user disconnects local RPC (or it becomes unavailable)
    And user waits for banner showing "Still connecting to Ink..."
    
    # Trigger RPC update from banner
    Then the "Update RPC" button appears on the banner
    When user clicks "Update RPC" on the banner
    And user is navigated to Edit Network screen
    And user switches default RPC to https://rpc-qnd.inkonchain.com
    
    # Verify analytics in Segment
    When user checks Segment dashboard for "Network Connection Banner RPC Updated" event
    Then the event property from_rpc_domain should be "custom" (local RPC is private)
    And the event property to_rpc_domain should be "rpc-qnd.inkonchain.com" (known public domain)

  Scenario: Verify rpc_domain for Infura networks using Switch to MetaMask default
    # Setup - Configure Arbitrum with local RPC
    Given user starts a local Ganache server: npx ganache --chain.chainId 42161
    And user navigates to Settings → Networks → Arbitrum One
    And user adds a new RPC endpoint: http://127.0.0.1:8545
    And user sets the local RPC as the default endpoint
    
    # Trigger degraded state
    When user stops the Ganache server (Ctrl+C)
    And user waits for banner showing "Still connecting to Arbitrum One..."
    
    # Switch to Infura via banner button
    Then the "Switch to MetaMask default RPC" button appears on the banner
    When user clicks "Switch to MetaMask default RPC"
    Then the toast "Updated to MetaMask default" appears
    
    # Verify analytics
    When user checks Segment for "Network Connection Banner Switch To MetaMask Default RPC Clicked"
    Then rpc_domain should be "custom" (the local RPC being switched from)
```

## **Screenshots/Recordings**

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before and after of your change. -->

### **Before**

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### **After**

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## **Pre-merge author checklist**

- [ ] I've followed [MetaMask Contributor
Docs](https://github.com/MetaMask/contributor-docs) and [MetaMask
Extension Coding
Standards](https://github.com/MetaMask/metamask-extension/blob/main/.github/guidelines/CODING_GUIDELINES.md).
- [ ] I've completed the PR template to the best of my ability
- [ ] I’ve included tests if applicable
- [ ] I’ve documented my code using [JSDoc](https://jsdoc.app/) format
if applicable
- [ ] I’ve applied the right labels on the PR (see [labeling
guidelines](https://github.com/MetaMask/metamask-extension/blob/main/.github/guidelines/LABELING_GUIDELINES.md)).
Not required for external contributors.

## **Pre-merge reviewer checklist**

- [ ] I've manually tested the PR (e.g. pull and build branch, run the
app, test code being changed).
- [ ] I confirm that this PR addresses all acceptance criteria described
in the ticket it closes and includes the necessary testing evidence such
as recordings and or screenshots.


<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> **Medium Risk**
> Changes privacy/analytics sanitization for RPC URLs by expanding
what’s considered “public” and moving the check behind a background RPC
call; misclassification could leak domains to metrics or over-redact
valid public endpoints.
> 
> **Overview**
> **Expands `isPublicEndpointUrl` to cover chainlist-known RPC
domains.** The public-endpoint check is moved into
`app/scripts/lib/util.ts`, now optionally allowing any hostname found in
the cached safe chainlist while explicitly filtering out `localhost`, IP
literals (v4/v6), and RFC 6761 special-use/reserved domains.
> 
> **Routes public-endpoint checks through the background for UI
metrics.** UI analytics in `useNetworkConnectionBanner` and the networks
form now call `submitRequestToBackground('isPublicEndpointUrl', [url])`
(with added error isolation), and the background controller exposes this
method using the runtime Infura project id. Tests were updated
accordingly, and `ip-regex` was added as a dependency.
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
f5769e0. This will update automatically
on new commits. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

Author: cryptodev-2s

app/scripts/lib/network-controller/messenger-action-handlers.test.ts

@@ -1,5 +1,5 @@
 import { HttpError } from '@metamask/controller-utils';
-import * as networkUtilsModule from '../../../../shared/lib/network-utils';
+import * as utilModule from '../util';
 import {
   onRpcEndpointDegraded,
   onRpcEndpointUnavailable,
@@ -14,8 +14,8 @@ describe('onRpcEndpointUnavailable', () => {
     Parameters<typeof networkControllerUtilsModule.shouldCreateRpcServiceEvents>
   >;
   let isPublicEndpointUrlMock: jest.SpyInstance<
-    ReturnType<typeof networkUtilsModule.isPublicEndpointUrl>,
-    Parameters<typeof networkUtilsModule.isPublicEndpointUrl>
+    ReturnType<typeof utilModule.isPublicEndpointUrl>,
+    Parameters<typeof utilModule.isPublicEndpointUrl>
   >;
 
   beforeEach(() => {
@@ -24,10 +24,7 @@ describe('onRpcEndpointUnavailable', () => {
       'shouldCreateRpcServiceEvents',
     );
 
-    isPublicEndpointUrlMock = jest.spyOn(
-      networkUtilsModule,
-      'isPublicEndpointUrl',
-    );
+    isPublicEndpointUrlMock = jest.spyOn(utilModule, 'isPublicEndpointUrl');
   });
 
   it('calls shouldCreateRpcServiceEvents with the correct parameters', () => {
@@ -170,8 +167,8 @@ describe('onRpcEndpointDegraded', () => {
     Parameters<typeof networkControllerUtilsModule.shouldCreateRpcServiceEvents>
   >;
   let isPublicEndpointUrlMock: jest.SpyInstance<
-    ReturnType<typeof networkUtilsModule.isPublicEndpointUrl>,
-    Parameters<typeof networkUtilsModule.isPublicEndpointUrl>
+    ReturnType<typeof utilModule.isPublicEndpointUrl>,
+    Parameters<typeof utilModule.isPublicEndpointUrl>
   >;
 
   beforeEach(() => {
@@ -180,10 +177,7 @@ describe('onRpcEndpointDegraded', () => {
       'shouldCreateRpcServiceEvents',
     );
 
-    isPublicEndpointUrlMock = jest.spyOn(
-      networkUtilsModule,
-      'isPublicEndpointUrl',
-    );
+    isPublicEndpointUrlMock = jest.spyOn(utilModule, 'isPublicEndpointUrl');
   });
 
   it('calls shouldCreateRpcServiceEvents with the correct parameters', () => {

app/scripts/lib/network-controller/messenger-action-handlers.ts

@@ -5,7 +5,7 @@ import {
   MetaMetricsEventName,
 } from '../../../../shared/constants/metametrics';
 import { onlyKeepHost } from '../../../../shared/lib/only-keep-host';
-import { isPublicEndpointUrl } from '../../../../shared/lib/network-utils';
+import { isPublicEndpointUrl } from '../util';
 import MetaMetricsController from '../../controllers/metametrics-controller';
 import { shouldCreateRpcServiceEvents } from './utils';
 

app/scripts/lib/util.test.js

@@ -30,6 +30,8 @@ import {
   extractRpcDomain,
   isKnownDomain,
   initializeRpcProviderDomains,
+  isPublicEndpointUrl,
+  isSpecialUseDomain,
 } from './util';
 
 // Mock the module
@@ -608,4 +610,145 @@ describe('app utils', () => {
       expect(extractRpcDomain('https://')).toBe('invalid');
     });
   });
+
+  describe('isPublicEndpointUrl', () => {
+    const MOCK_INFURA_PROJECT_ID = 'test-project-id';
+
+    it('should return true for Infura URLs', () => {
+      expect(
+        isPublicEndpointUrl(
+          `https://mainnet.infura.io/v3/${MOCK_INFURA_PROJECT_ID}`,
+          MOCK_INFURA_PROJECT_ID,
+        ),
+      ).toBe(true);
+    });
+
+    it('should return false for unknown URLs', () => {
+      expect(
+        isPublicEndpointUrl(
+          'https://unknown.example.com',
+          MOCK_INFURA_PROJECT_ID,
+        ),
+      ).toBe(false);
+    });
+
+    describe('localhost and IP addresses', () => {
+      it('should return false for localhost', () => {
+        expect(
+          isPublicEndpointUrl('http://localhost:8545', MOCK_INFURA_PROJECT_ID),
+        ).toBe(false);
+      });
+
+      it('should return false for any IPv4 address', () => {
+        // Loopback
+        expect(
+          isPublicEndpointUrl('http://127.0.0.1:8545', MOCK_INFURA_PROJECT_ID),
+        ).toBe(false);
+        // Private ranges
+        expect(
+          isPublicEndpointUrl('http://10.0.0.1:8545', MOCK_INFURA_PROJECT_ID),
+        ).toBe(false);
+        expect(
+          isPublicEndpointUrl(
+            'http://192.168.1.1:8545',
+            MOCK_INFURA_PROJECT_ID,
+          ),
+        ).toBe(false);
+        // Public IPs should also return false (public providers use domain names)
+        expect(
+          isPublicEndpointUrl('http://8.8.8.8:8545', MOCK_INFURA_PROJECT_ID),
+        ).toBe(false);
+      });
+
+      it('should return false for any IPv6 address', () => {
+        expect(
+          isPublicEndpointUrl('http://[::1]:8545', MOCK_INFURA_PROJECT_ID),
+        ).toBe(false);
+        expect(
+          isPublicEndpointUrl(
+            'http://[2001:db8::1]:8545',
+            MOCK_INFURA_PROJECT_ID,
+          ),
+        ).toBe(false);
+      });
+    });
+  });
+
+  describe('isSpecialUseDomain', () => {
+    describe('RFC 6761 special-use TLDs', () => {
+      it('should return true for .test TLD', () => {
+        expect(isSpecialUseDomain('myapp.test')).toBe(true);
+        expect(isSpecialUseDomain('rpc.myapp.test')).toBe(true);
+      });
+
+      it('should return true for .localhost TLD', () => {
+        expect(isSpecialUseDomain('myapp.localhost')).toBe(true);
+        expect(isSpecialUseDomain('rpc.myapp.localhost')).toBe(true);
+      });
+
+      it('should return true for .invalid TLD', () => {
+        expect(isSpecialUseDomain('myapp.invalid')).toBe(true);
+        expect(isSpecialUseDomain('rpc.myapp.invalid')).toBe(true);
+      });
+
+      it('should return true for .example TLD', () => {
+        expect(isSpecialUseDomain('myapp.example')).toBe(true);
+        expect(isSpecialUseDomain('rpc.myapp.example')).toBe(true);
+      });
+
+      it('should return true for .local TLD', () => {
+        expect(isSpecialUseDomain('myapp.local')).toBe(true);
+        expect(isSpecialUseDomain('rpc.myapp.local')).toBe(true);
+      });
+    });
+
+    describe('RFC 6761 reserved example domains', () => {
+      it('should return true for example.com', () => {
+        expect(isSpecialUseDomain('example.com')).toBe(true);
+        expect(isSpecialUseDomain('rpc.example.com')).toBe(true);
+        expect(isSpecialUseDomain('api.rpc.example.com')).toBe(true);
+      });
+
+      it('should return true for example.net', () => {
+        expect(isSpecialUseDomain('example.net')).toBe(true);
+        expect(isSpecialUseDomain('rpc.example.net')).toBe(true);
+        expect(isSpecialUseDomain('api.rpc.example.net')).toBe(true);
+      });
+
+      it('should return true for example.org', () => {
+        expect(isSpecialUseDomain('example.org')).toBe(true);
+        expect(isSpecialUseDomain('rpc.example.org')).toBe(true);
+        expect(isSpecialUseDomain('api.rpc.example.org')).toBe(true);
+      });
+    });
+
+    describe('case insensitivity', () => {
+      it('should be case insensitive', () => {
+        expect(isSpecialUseDomain('EXAMPLE.COM')).toBe(true);
+        expect(isSpecialUseDomain('MyApp.TEST')).toBe(true);
+        expect(isSpecialUseDomain('RPC.Example.Org')).toBe(true);
+      });
+    });
+
+    describe('valid public domains', () => {
+      it('should return false for regular domains', () => {
+        expect(isSpecialUseDomain('infura.io')).toBe(false);
+        expect(isSpecialUseDomain('mainnet.infura.io')).toBe(false);
+        expect(isSpecialUseDomain('alchemy.com')).toBe(false);
+        expect(isSpecialUseDomain('rpc.ankr.com')).toBe(false);
+      });
+
+      it('should return false for domains containing but not ending with special TLDs', () => {
+        expect(isSpecialUseDomain('test-rpc.com')).toBe(false);
+        expect(isSpecialUseDomain('example-provider.io')).toBe(false);
+        expect(isSpecialUseDomain('localhost-rpc.net')).toBe(false);
+      });
+    });
+
+    describe('edge cases', () => {
+      it('should return false for empty string', () => {
+        expect(isSpecialUseDomain('')).toBe(false);
+      });
+    });
+  });
 });