Re: [tcpm] [Technical Errata Reported] RFC7413 (4239)

[Joe Touch <[e-mail]>]

On 1/23/2015 7:57 PM, Matthew Luckie wrote:
>>> Notes
>>> -----
>>> A Nil fast-open option has an option length of 2.
>>
>> Agreed.
>>
>>> A length field of zero would mean an invalid TCP option.
>>
>> Disagree. The correct reason is, IMO:
>>
>> 	The Nil option has no bytes beyond the Kind and Length
>> 	fields required in all TCP options, and the Length field
>> 	includes the space used for Kind and Length.
>>
>> The interpretation of an option with a 0 length should not be discussed
>> in the errata or future updates to this doc; it is out of scope.
>>
>> (AFAICT, if it were observed, the entire segment would have to be deemed
>> invalid, not just that individual option. But that's not germane to this
>> errata).
>
> I do not think that the reasoning behind this errata needs to be
> discussed in future updates to the RFC (I put my reasoning in the
> Notes field of the errata form) but I absolutely believe that a TCP
> option defined after RFC793 with a length of zero is an invalid option
> that will cause a TCP receiver to stop processing the options.

It should be interpreted as a malformed segment, not simply stop the 
processing of the options.

Joe