wp_validate_redirect()

wp_validate_redirect() — Validates a URL for use in a redirect. Checks whether the $location is using an allowed host, if it has an absolute path. A plugin can therefore set or remove allowed host(s) to or from the list. If the host is not allowed, then the redirect is to $fallback_url supplied.

Inputs: $location (string): The redirect to validate. $fallback_url (string): The value to return if $location is not allowed.

Returns string: Redirect-sanitized URL.