class HTTPClient::NegotiateAuth

def challenge(uri, param_str)

Challenge handler: remember URL and challenge token for response. 
def challenge(uri, param_str)
  return false unless NTLMEnabled
  if param_str.nil? or @challenge[uri].nil?
    c = @challenge[uri] = {}
    c[:state] = :init
    c[:authphrase] = ""
  else
    c = @challenge[uri]
    c[:state] = :response
    c[:authphrase] = param_str
  end
  true
end