Add filter to prevent user creation during site creation

[mackensen]

We administer a multisite environment with external (LDAP) authentication configured. We do not allow local accounts. Our procedure when creating a new site is to add the soon-to-be-administrator from external authentication to the top-level site (if they did not already exist) before creating the site. If someone misses that first step, we wind up with an unwanted local account which then has to be fixed. What would be cool is a filter/hook in wp-admin/network/site-new.php that attaches to email_exists and lets you stop the site creation process if the user doesn't exist.

[SergeyBiryukov]

A workaround:

function wp33631_check_for_existing_user_during_site_creation() {
	if ( ! isset( $_REQUEST['action'] ) || 'add-site' !== $_REQUEST['action'] ) {
		return;
	}

	if ( ! email_exists( $_POST['blog']['email'] ) ) {
		wp_die( 'User does not exist.' );
	}
}
add_action( 'admin_init', 'wp33631_check_for_existing_user_during_site_creation' );

[mackensen]

Working on this at WCUS Contributor Day. I've added a new action network_site_new_created_user_pending which fires immediately before user creation, so you could hook into it with a simple wp_die or whatever else you might want to do. I could see external auth attempting to auto provision the account.

[rachelbaker]

@mackensen Looks like you have wrong parameter type in the inline docs for the filter. Can you check it?

[mackensen]

Corrected param type

[rachelbaker]

Fixed spacing and added version to inline docs

[rachelbaker]

In 35786:

Multisite: Add hook before a new user is created during the creation of a new site.

New network_site_new_created_user_pending action fires before a new user will be created via the network site-new.php page.

Props mackensen
Fixes #33631

[jeremyfelt]

We can probably tighten up the naming on this a bit to be more clear. Nothing is pending yet, as we still need to go through some other user checks to see if the email is valid before continuing. Using pre_ seems to make sense. I've added 33631.2.diff​ with this change.

Thoughts?

[rachelbaker]

In 35789:

Multisite: Clarify purpose of hook from [35786] and match our naming convention.

network_site_new_created_user_pending -> pre_network_site_new_created_user

See #33631

[DrewAPicture]

In 36826:

Docs: Minorly improve the hook doc summary for the pre_network_site_new_created_user action, introduced in [35786].

See #33631. See #35986.