Re: Proposed Resolution to Issue 198: Attribute Concatenation/Splitting

[Barney Wolff <barney@databus.com>]

On Thu, Sep 28, 2006 at 11:27:23PM -0700, Bernard Aboba wrote:
>   Tag
> 
>      The Tag field is one octet, and MUST always be present.  It is
>      used to identify the filter rule that is represented.  Where a
>      single filter rule exceeds 253 octets in length, the rule MUST be
>      encoded across multiple NAS-Filter-Rule attributes, each with the
>      same Tag value; Tag values MUST be unique for each filter rule
>      present in a RADIUS packet with the exception of a Tag value of
>      '0' (0x30).  The value of '0' (0x30) in the Tag field indicates
>      that the attribute contains a filter rule that does not exceed 253
>      octets in length; as a result attributes with a Tag value of 0x30
>      MUST NOT be concatenated, and one or more Filter-Rule attributes
>      with a tag value of 0x30 may be included in a single RADIUS
>      packet, each describing a single filter rule.

May I suggest that NAS-Filter-Rule attributes with different tag values
MUST NOT appear between the segments into which a long rule is split?
There is no benefit to the sender to allowing anything else, and
considerable nuisance to the receiver.

Also, I suggest that a rule which is not split MUST have tag value '0'.
Again, there is no value to the sender for anything else, and this way
the receiver can know whether a rule is going to be extended.  Perhaps
the language implying that a rule <252 octets MUST NOT be split should
be made more explicit, too.

As an aside, it is a general misfeature of RADIUS that senders are
allowed to do things, such as random ordering of attributes, that have
little value for the sender but cause hardship for the receiver.  We are
all so used to this nuisance that we hardly perceive it as such.

-- 
Barney Wolff         I never met a computer I didn't like.

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