class HTTPClient::SSPINegotiateAuth

def get(req)
  return nil unless SSPIEnabled || GSSAPIEnabled
  target_uri = req.header.request_uri
  domain_uri, param = @challenge.find { |uri, v|
    Util.uri_part_of(target_uri, uri)
  }
  return nil unless param
  state = param[:state]
  authenticator = param[:authenticator]
  authphrase = param[:authphrase]
  case state
  when :init
    if SSPIEnabled
      authenticator = param[:authenticator] = Win32::SSPI::NegotiateAuth.new
      return authenticator.get_initial_token(@scheme)
    else # use GSSAPI
      authenticator = param[:authenticator] = GSSAPI::Simple.new(domain_uri.host, 'HTTP')
      # Base64 encode the context token
      return [authenticator.init_context].pack('m').gsub(/\n/,'')
    end
  when :response
    @challenge.delete(domain_uri)
    if SSPIEnabled
      return authenticator.complete_authentication(authphrase)
    else # use GSSAPI
      return authenticator.init_context(authphrase.unpack('m').pop)
    end
  end
  nil
end