WordPress Multisite with Azure B2C redirect_urls after Login

Question

My WP multisite has more than 300 sites which means I need to store all 300 redirect_urls in Azure AD B2C, but this number of redirect_urls cannot be stored in AD B2C as the maximum number of redirect URIs is 256.

What I do is that when the user logs in through www.abc1.com/wp-admin, it first redirects to B2C login page with the default redirect URL (www.abc.com) that I set. Once the token is verified, the user is redirected to their site (www.abc1.com).

But it doesn't seem to work. I am even not sure if it is the best approach to redirect the user to site they want to access by this way.

//fetch the user' site id and redirect to the site.
$user_blogs = get_blogs_of_user($userID);
if (!empty($user_blogs)) {
$siteInfo = array();
foreach ($user_blogs as $site_id => $site_values) {
$siteInfo[] = $site_values->siteurl;
}
$redirect_url = $siteInfo[0] ; // to the primary site..
}

// Set cookies to authenticate on WP side
wp_set_auth_cookie($userID);

//Redirect to primary site that assigned to the user
wp_safe_redirect($redirect_url);

Answer 1

I can see a few issues with this approach:

1. If the user doesn't belong to a site yet, they won't get redirected correctly because $redirect_url won't be defined.
2. If the user belongs to more than 1 site, they will always be redirected to the site with the lowest ID, not necessarily the one they're trying to log into.

Have you tried any Azure SSO plugins? I built an intranet for a client that uses Azure for employees to log into the site, and we had great results using Single Sign-on with Azure Active Directory (for WordPress). It's supposed to work with multisite; you'll just need to make sure it's configured correctly on each site.