class Acme::Client

def fetch_chain(response, limit = 10)
  links = response.headers['link']
  if limit.zero? || links.nil? || links['up'].nil?
    []
  else
    issuer = connection.get(links['up'])
    [OpenSSL::X509::Certificate.new(issuer.body), *fetch_chain(issuer, limit - 1)]
  end
end