chubarovNick/thunderer

module Thunderer
  # This class is an extension for the Faye::RackAdapter.
  # It is used inside of Thunderer.faye_app.
  class FayeExtension
    # Callback to handle incoming Faye messages. This authenticates both
    # subscribe and publish calls.
    def incoming(message, callback)
      if message['channel'] == '/meta/subscribe'
        authenticate_subscribe(message)
      elsif message['channel'] !~ %r{^/meta/}
        authenticate_publish(message)
      end
      callback.call(message)
    end

  private

    # Ensure the subscription signature is correct and that it has not expired.
    def authenticate_subscribe(message)
      subscription = Thunderer.subscription(:channel => message['subscription'], :timestamp => message['ext']['thunderer_timestamp'])
      if message['ext']['thunderer_signature'] != subscription[:signature]
        message['error'] = 'Incorrect signature.'
      elsif Thunderer.signature_expired? message['ext']['thunderer_timestamp'].to_i
        message['error'] = 'Signature has expired.'
      end
    end

    # Ensures the secret token is correct before publishing.
    def authenticate_publish(message)
      if Thunderer.config.secret_token.nil?
        raise Error, 'No secret_token config set, ensure thunderer.yml is loaded properly.'
      elsif message['ext']['thunderer_secret_token'] != Thunderer.config.secret_token

        message['error'] = 'Incorrect token.'
      else
        message['ext']['thunderer_secret_token'] = nil
      end
    end
  end
end