Restrict the user access in multi site for non-assigned blogs

Question

What is the better way to restrict a user of any role being logging into a blog of wordpress multisite network if he/she is not assigned to that particular blog as a user even though he is an administrator of another blog in that network. I hope it can be done using get_blogs_of_user( $user ); function where $user is the username of person who trying to login.

EDIT: My code as follows.

 $info = array();
    $info['user_login'] = $_POST['username'];
    $info['user_password'] = $_POST['password'];
    $info['remember'] = true;

 $user_signon = wp_signon($info, false);
    if (is_wp_error($user_signon)) {
        echo json_encode(array('loggedin' => false, 'message' => __('Invalid Credentials.')));
    } else {
    $get_blogs = get_blogs_of_user(get_user_by('login',$info['user_login'])->ID);
    $is_has_access = array_search(get_current_blog_id(), array_column($get_blogs, 'userblog_id'));
    if (!$is_has_access) {
         wp_logout();
        echo json_encode(array('loggedin' => false, 'message' => __('You have no permission to access.')));
    } else {
            echo json_encode(array('loggedin' => true, 'message' => __('Login successful')));
       }
    }

Is there any better ways?

Answer 1

is_user_logged_in() is a pluggable function, which means you can override its functionality. That's probably where I'd start.

Something like this may do what you're looking for. This is untested code and comes with no warranties of any kind.

function is_user_logged_in() {
    $user = wp_get_current_user();
    $current_blog_id = get_current_blog_id();
    $allowed = false;
    $blogs_of_user = get_blogs_of_user( $user->ID );
    foreach( $blogs_of_user as $blog ) {
        if( $blog->userblog_id == $current_blog_id ) {
            $allowed = true;
        }
    }

    if( ! $allowed ) {
        return false;
    }

    return $user->exists();

}

References

• Pluggable Functions
• is_user_logged_in()
• wp_get_current_user()
• get_current_blog_id()
• get_blogs_of_user()