[asterisk-users] Invite + decreasing sequence number => 500 Error?

[Benoit Panizzon]

Hi Matt

> It's not a bug - decrementing the CSeq header field value is directly in
> violation of RFC 3261.  From section 22.2:
> 
>    When a UAC resubmits a request with its credentials after receiving a
>    401 (Unauthorized) or 407 (Proxy Authentication Required) response,
>    it MUST increment the CSeq header field value as it would normally
>    when sending an updated request.

I sent this to the developers of the C3 Softswitch.

They answered by quoting this part from RFC 3261, 8.1.3.5 Processing 4xx 
Responses:

   If a 401 (Unauthorized) or 407 (Proxy Authentication Required)
   response is received, the UAC SHOULD follow the authorization
   procedures of Section 22.2 and Section 22.3 to retry the request with
   credentials.
[...]
   In all of the above cases, the request is retried by creating a new
   request with the appropriate modifications.  This new request
   constitutes a new transaction and SHOULD have the same value of the
   Call-ID, To, and From of the previous request, but the CSeq should
   contain a new sequence number that is one higher than the previous.

Here it says it should, so a lower CSEQ is allowed and asterisk is wrong they 
say.

Well I'll quote them the _MUST_ part of section 22.2

Thanks

Benoit Panizzon
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