CSRF with req.evn['rack.session']

[456asf]

def safe?
  return req.get? || req.head? ||
    req.params["csrf_token"] == token ||#token create every time new one
    req.env["HTTP_X_CSRF_TOKEN"] == token
end
Change code ...
def existing_token
  session[:csrf_token]
end

def safe?
  return req.get? || req.head? ||
    req.params["csrf_token"] == existing_token ||
    req.env["HTTP_X_CSRF_TOKEN"] == existing_token
end

Also 
 def session
          return req.env["rack.session"]
        end

return nil with errors  like this 
undefined method `[]' for nil:NilClass session[:csrf_token] ||= SecureRandom.base64(32) ^^^^^^^^^^^^^