Firestore restrict to certain users

gistfile1.txt

function getAllowedUser() {
  return get(/databases/$(database)/documents/settings/allowedUsers) 
} 

function validUser() { 
  let allowedUsers = getAllowedUser(); 
  return request.auth.token.email in allowedUsers.data.emails 
    || 
   request.auth.token.email.split("@")[1] in allowedUsers.data.domains 
  }
  
match /{document=**} { 
  allow read, write: if request.auth != null && validUser() && request.auth.token.email_verified 
}