[AFS3-std] rxgk key version number of value zero

[Benjamin Kaduk]

On Tue, 11 Dec 2012, Simon Wilkinson wrote:

>
> On 11 Dec 2012, at 20:05, Michael Meffie wrote:
>
>>   The Checksum field allows for an optional packet checksum.  A zero
>>   checksum field value means that checksums are not being computed.  An
>>   Rx security protocol (identified by the security field, described
>>   below) may choose to use this field to transport some checksum of the
>>   packet that is computed and verified by it (for example, rxkad uses
>>   this field for a cryptographic header checksum).  Rx itself makes no
>>   use of the checksum field.
>
> Technically, this is a "spare" field that rxkad hijacked to use for 
> checksums. I don't think there's any particular problem with rxgk 
> assigning it a different meaning. One possible consideration is that the 
> OpenAFS RX stack notes the presence of non-zero values here, and the 
> rx_IsUsingPktCksum() function will return true if it has seen any in the 
> life of the connection. However, the only caller of this function in the 
> OpenAFS code is rxkad, and I don't think it makes much sense outside of 
> rxkad itself.

Thanks for adding the confirmation.  I was pretty sure that we didn't 
care, but explicitly discussing the issue on-list seems preferable to 
silently making assumptions.

-Ben