Opened 11 years ago

#23 new enhancement

Which elements a particular normative passage applies to

Reported by: worley@… Owned by:
Priority: major Milestone:
Component: rfc4244bis Version:
Severity: In WG Last Call Keywords:
Cc:

Description

In regard to the general notes in section 4.1:

Prior to any application usage of the information by the UAC (e.g., debug), the validity SHOULD be ascertained. The entries SHOULD be evaluated to determine gaps in indices, which could indicate that an entry has been maliciously removed. Either way, an application SHOULD be aware of potentially missing information. The interpretation of the information in the History-Info header by a UAC in a request depends upon the specific applications supported by the UAC. Application considerations and guidelines are provided in section 7.

It's not clear why this is phrased to refer only to UACs, as UASs seem to be the most likely application, and in any case, there is no particular limitation the what SIP elements might want to examine History-Info. A better phrasing would be:

Prior to any application usage of the information by a SIP element (e.g., debugging of request routing), the validity of the History-Info values SHOULD be ascertained. An application SHOULD be aware of the possibility of missing or incorrect values. The interpretation of the information in the History-Info header by a UAS in a request depends upon the specific applications supported by the UAS. Application considerations and guidelines are provided in section 7.

This is an instance of a more general exposition problem: Many normative parts of the exposition specifically identify their target as UAS, UAC, proxy, etc. even though the processing described applies to a larger class of elements.

For instance, there are behaviors that are specific to "any element that receives a request containing History-Info", but (IIRC), the same rules are stated separately for UASs and proxies.

Similarly, since both proxies and UACs can act on 3xx responses, the rules for handling redirection should be labeled as such.

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