def cmd_pass(param)
      send_response "202 User already logged in" and return unless @user.nil?
      send_param_required and return if param.nil?
      send_response "530 password with no username" and return if @requested_user.nil?

      # return an error message if:
      #  - the specified username isn't in our system
      #  - the password is wrong

      @driver.authenticate(@requested_user, param) do |result|
        if result
          @name_prefix = "/"
          @user = @requested_user
          @requested_user = nil
          send_response "230 OK, password correct"
        else
          @user = nil
          send_response "530 incorrect login. not logged in."
        end
      end
    end
def cmd_pass(param)
      send_response "202 User already logged in" and return unless @user.nil?
      send_param_required and return if param.nil?
      send_response "530 password with no username" and return if @requested_user.nil?

      # return an error message if:
      #  - the specified username isn't in our system
      #  - the password is wrong

      @driver.authenticate(@requested_user, param) do |result|
        if result
          @name_prefix = "/"
          @user = @requested_user
          @requested_user = nil
          send_response "230 OK, password correct"
        else
          @user = nil
          send_response "530 incorrect login. not logged in."
        end
      end
    end
handle the PASS FTP command. This is the second stage of a user logging in