class Acme::Client::CertificateRequest

def add_extension(csr)
  return if @names.size <= 1
  extension = OpenSSL::X509::ExtensionFactory.new.create_extension(
    'subjectAltName', @names.map { |name| "DNS:#{name}" }.join(', '), false
  )
  csr.add_attribute(
    OpenSSL::X509::Attribute.new(
      'extReq',
      OpenSSL::ASN1::Set.new([OpenSSL::ASN1::Sequence.new([extension])])
    )
  )
end