Re: [IPFIX] [Technical Errata Reported] RFC7011 (7413)

On first glance, this seems (1) correct and (2) a useful clarification, and superior to both of the other proposed possible fixes. So I think this one can be verified.

> On 3 Apr 2023, at 01:17, RFC Errata System <rfc-editor@rfc-editor.org> wrote:
> 
> The following errata report has been submitted for RFC7011,
> "Specification of the IP Flow Information Export (IPFIX) Protocol for the Exchange of Flow Information".
> 
> --------------------------------------
> You may review the report below and at:
> https://www.rfc-editor.org/errata/eid7413
> 
> --------------------------------------
> Type: Technical
> Reported by: Michael Duggan <mwd@cert.org>
> 
> Section: 3.4.1
> 
> Original Text
> -------------
> Field Count
> 
>      Number of fields in this Template Record.
> 
> Corrected Text
> --------------
> Field Count
> 
>      Number of fields in this Template Record.  The Field Count MUST NOT be zero.
> 
> The sum of the Field Lengths of the Field Specifiers of a Template Record MUST NOT be zero.
> 
> Notes
> -----
> If the size of data record corresponding to a template can ever be zero, then  the only valid size for such a data set is the size of the set header.  For normal cases any size greater than that of the set header is a valid size, since records are read from a set until the number of octets remaining is less than the smallest possible record size for that set.  If a record size can be zero, then any number of bytes past the header cannot be padding (is not smaller than the smallest record), and a conforming implementation might return an infinite number of zero-sized records.  As this could cause a denial of service situation, rejecting templates that define zero-sized records seems to be the simplest solution.
> 
> Similar text may be necessary for Option Template records, though the fact that the scope count MUST be non-zero may negate the necessity.
> 
> Other possible fixes:
> * Require all Field Specifiers to have a non-zero Field Length.  This may be an even simpler solution, but I can envision uses for zero-sized data elements, especially for elements that MAY be of variable length.
> * Require a conforming implementation to reject or ignore data sets for zero-sized templates.
> 
> Instructions:
> -------------
> This erratum is currently posted as "Reported". If necessary, please
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> rejected. When a decision is reached, the verifying party  
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> 
> --------------------------------------
> RFC7011 (draft-ietf-ipfix-protocol-rfc5101bis-10)
> --------------------------------------
> Title               : Specification of the IP Flow Information Export (IPFIX) Protocol for the Exchange of Flow Information
> Publication Date    : September 2013
> Author(s)           : B. Claise, Ed., B. Trammell, Ed., P. Aitken
> Category            : INTERNET STANDARD
> Source              : IP Flow Information Export
> Area                : Operations and Management
> Stream              : IETF
> Verifying Party     : IESG
> 
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