Fix malformed ActivityPub handles for email-based logins #2082

obenland · 2025-08-19T17:20:57Z

Fixes #2070.

Proposed changes:

Modified get_preferred_username() method in includes/model/class-user.php to detect email-based logins and sanitize them using sanitize_title()
Added comprehensive test coverage in tests/includes/model/class-test-user.php to verify proper email username sanitization
Ensures ActivityPub handles are properly formatted as @[email protected] instead of malformed @[email protected]@domain.com

Other information:

Have you written new tests for your changes, if applicable?

Testing instructions:

Setup

Install and activate the ActivityPub plugin in a WordPress test environment
Install and configure Site Kit with Google authentication (or manually create a user with email-based login)

Test Case 1: Email-based Login from Site Kit

Create a test user via Site Kit Google login, which typically creates a username like [email protected]
Navigate to the user's ActivityPub profile page or use the webfinger endpoint
Expected result: ActivityPub handle should be @[email protected]
Previous buggy behavior: Handle was malformed as @[email protected]@yourdomain.com

Test Case 2: Manual Email-based Username

Create a user with login name [email protected]
Check their ActivityPub handle via webfinger or profile
Expected result: Handle should be @[email protected]

Test Case 3: Normal Username (Regression Test)

Create a user with normal login name normaluser
Check their ActivityPub handle
Expected result: Handle should be @[email protected] (unchanged behavior)

Test Case 4: Run Unit Tests

npm run env-test -- --filter=test_email_username_sanitization

Expected result: All tests should pass

Changelog entry

Automatically create a changelog entry from the details below.

Changelog Entry Details

Significance

Patch

Type

Fixed - for any bug fixes

Message

Fix malformed ActivityPub handles for users with email-based logins (e.g., from Site Kit Google authentication)

Sanitize email-based usernames (e.g., from Site Kit Google login) to prevent malformed ActivityPub handles like @[email protected]@domain.com. - Modified get_preferred_username() to detect and sanitize email logins - Added comprehensive test coverage for email username sanitization - Ensures proper webfinger format without double @ symbols Fixes #2070.

Copilot

Pull Request Overview

This PR fixes malformed ActivityPub handles for users with email-based login names, such as those created through Site Kit Google authentication. The issue occurred when usernames containing "@" symbols resulted in double "@" symbols in ActivityPub handles.

Modified get_preferred_username() to sanitize email-based usernames using sanitize_title()
Added comprehensive test coverage to verify proper email username sanitization
Ensures ActivityPub handles are properly formatted without malformed double "@" symbols

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
includes/model/class-user.php	Modified `get_preferred_username()` to detect and sanitize email-based login names
tests/includes/model/class-test-user.php	Added comprehensive test cases for email username sanitization scenarios

_{Tip: Customize your code reviews with copilot-instructions.md. Create the file or learn how to get started.}

Prefixed str_contains with a backslash to ensure the global PHP function is used, preventing potential issues with overridden or namespaced functions.

…Automattic/wordpress-activitypub into fix/email-username-sanitization

Fix PHPCS alignment warnings for variable assignments.

Jiwoon-Kim · 2025-08-19T18:19:45Z

The profile URL is generated as:
https://travel-in-busan.com/author/kimjiwoon75gmail-com/

To maintain consistency with the ActivityPub handle, instead of replacing @ with a hyphen, the @ should be omitted entirely.

👉 Desired format:
@[email protected]

is not very “clean” as a username.

It may be worth considering a redirect mechanism in the future so that such legacy usernames can point to a cleaner, newly chosen identifier.

Of course, this would also require solving the name collision problem (e.g., if two users try to adopt the same “cleaned” username).

👉 In practice, this would mean:

Keep the legacy handle for backwards compatibility.

Allow the user/admin to register a new canonical handle.

Set up a redirect/alias system so that old mentions and followers still resolve correctly.

This should be addressed together with the ability for users to edit their blog profile handle. For example, mechanisms that allow arbitrary manipulation of the handle—such as using the posts page slug as the handle—should be prevented. The goal is to maintain consistency and integrity of ActivityPub handles across posts and profiles.

Use explicit string replacement instead of sanitize_title() to ensure dots are converted to dashes as expected by tests. Also use filter_var() for proper email validation.

Jiwoon-Kim · 2025-08-25T17:17:36Z

https://wordpress.org/support/topic/activitypub-handle-format-issue-with-google-login/#post-18612844

pfefferle · 2025-08-25T17:26:19Z

@obenland you use a different formatter than core, so it is not possible to run a webfinger lookup. I think core simply removes the @ instead of replacing it with a -.

pfefferle · 2025-08-25T17:30:33Z

includes/model/class-user.php

+
+		// Handle cases where login is an email address (e.g., from Site Kit Google login).
+		if ( \filter_var( $login, FILTER_VALIDATE_EMAIL ) ) {
+			$login = \str_replace( array( '@', '.' ), '-', $login );


What about:

Suggested change

$login = \str_replace( array( '@', '.' ), '-', $login );

$login = \sanitize_title( $login );

???

pfefferle · 2025-08-25T17:32:55Z

includes/model/class-user.php

+
+		// Handle cases where login is an email address (e.g., from Site Kit Google login).
+		if ( \filter_var( $login, FILTER_VALIDATE_EMAIL ) ) {
+			$login = \str_replace( array( '@', '.' ), '-', $login );


this might be even better and should be the same result:

Suggested change

$login = \str_replace( array( '@', '.' ), '-', $login );

$login = \get_the_author_meta( 'user_nicename', $this->_id );

I guess it comes down to the expectations we have towards what makes for an appealing handle. a49da59 moved away from sanitize_title() to transition fediverse handles from usernamegmail-com to username-gmail-com.

The latter might be a bit nicer, but happy to defer if you have another preference. I don't feel strongly about it.

It might look nicer, but it breaks the lookup! If you stick with the custom formatter you would have to also add support to the Users::get_by_* functions

Thanks that's helpful!

Updated the logic in User::get_preferred_username() to use the user's nicename when the login is an email address, instead of replacing '@' and '.' with dashes. Adjusted related tests to match the new behavior.

Copilot AI review requested due to automatic review settings August 19, 2025 17:20

obenland self-assigned this Aug 19, 2025

obenland requested a review from pfefferle August 19, 2025 17:20

Add changelog

477d973

Copilot AI reviewed Aug 19, 2025

View reviewed changes

obenland added 3 commits August 19, 2025 12:24

Add global namespace to str_contains in User model

5eeb2ed

Prefixed str_contains with a backslash to ensure the global PHP function is used, preventing potential issues with overridden or namespaced functions.

Merge branch 'fix/email-username-sanitization' of https://github.com/…

e89eb14

…Automattic/wordpress-activitypub into fix/email-username-sanitization

Fix code style alignment in test

1a3d797

Fix PHPCS alignment warnings for variable assignments.

This comment was marked as duplicate.

Sign in to view

Jiwoon-Kim mentioned this pull request Aug 19, 2025

ActivityPub Handle Format Issue with Google Login google/site-kit-wp#11256

Open

Fix email username sanitization logic

a49da59

Use explicit string replacement instead of sanitize_title() to ensure dots are converted to dashes as expected by tests. Also use filter_var() for proper email validation.

pfefferle reviewed Aug 25, 2025

View reviewed changes

Use user_nicename for preferred username from email

1f7c98a

Updated the logic in User::get_preferred_username() to use the user's nicename when the login is an email address, instead of replacing '@' and '.' with dashes. Adjusted related tests to match the new behavior.

pfefferle approved these changes Aug 25, 2025

View reviewed changes

Merge branch 'trunk' into fix/email-username-sanitization

cd59f2b

obenland merged commit 4cc26df into trunk Aug 25, 2025
13 checks passed

obenland deleted the fix/email-username-sanitization branch August 25, 2025 19:43

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Uh oh!

Fix malformed ActivityPub handles for email-based logins #2082

Fix malformed ActivityPub handles for email-based logins #2082

Uh oh!

obenland commented Aug 19, 2025

Uh oh!

Copilot AI left a comment

Uh oh!

This comment was marked as duplicate.

Jiwoon-Kim commented Aug 19, 2025 •

edited

Loading

Uh oh!

Jiwoon-Kim commented Aug 25, 2025

Uh oh!

pfefferle commented Aug 25, 2025 •

edited

Loading

Uh oh!

pfefferle Aug 25, 2025

Uh oh!

pfefferle Aug 25, 2025

Uh oh!

obenland Aug 25, 2025

Uh oh!

pfefferle Aug 25, 2025

Uh oh!

obenland Aug 25, 2025

Uh oh!

Uh oh!

Uh oh!

	$login = \str_replace( array( '@', '.' ), '-', $login );
	$login = \sanitize_title( $login );

	$login = \str_replace( array( '@', '.' ), '-', $login );
	$login = \get_the_author_meta( 'user_nicename', $this->_id );

Fix malformed ActivityPub handles for email-based logins #2082

Fix malformed ActivityPub handles for email-based logins #2082

Uh oh!

Conversation

obenland commented Aug 19, 2025

Proposed changes:

Other information:

Testing instructions:

Setup

Test Case 1: Email-based Login from Site Kit

Test Case 2: Manual Email-based Username

Test Case 3: Normal Username (Regression Test)

Test Case 4: Run Unit Tests

Changelog entry

Significance

Type

Message

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull Request Overview

Reviewed Changes

Uh oh!

This comment was marked as duplicate.

Jiwoon-Kim commented Aug 19, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

Jiwoon-Kim commented Aug 25, 2025

Uh oh!

pfefferle commented Aug 25, 2025 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

pfefferle Aug 25, 2025

Choose a reason for hiding this comment

Uh oh!

pfefferle Aug 25, 2025

Choose a reason for hiding this comment

Uh oh!

obenland Aug 25, 2025

Choose a reason for hiding this comment

Uh oh!

pfefferle Aug 25, 2025

Choose a reason for hiding this comment

Uh oh!

obenland Aug 25, 2025

Choose a reason for hiding this comment

Uh oh!

Uh oh!

Uh oh!

Jiwoon-Kim commented Aug 19, 2025 •

edited

Loading

pfefferle commented Aug 25, 2025 •

edited

Loading