Re: [Sipp-users] Via problem with CANCEL and INVITE

[Olivier J. <oja...@gm...>]

On 3/29/06, Artur Silveira da Cunha <Art...@al...> wr=
ote:
> Hi,
>
> A coworker transmits me the following problem with INVITE and CANCEL and
> how to resolve VIA headers with sipp.
>
> The INVITE has several VIA lines in the header
> The CANCEL normally has only one VIA header
>
> He has the following scenario:
>
> <rcv INVITE> // fullfill the [last_Via] parameter
>    // regexp Via header with $1, fullfull only one VIA line and the
> other VIA lines are lost
> <send reply>  // VIA can be fulfilled with [last_Via]
>
> <rcv CANCEL> // fullfill the [last_Via] parameter
> <reply 200 OK> // VIA can be fulfilled with [last_Via]
> ...
> <send  BYE> // can't use the [last_Via] because it is the CANCEL
> originated, and it don't knows how to store the VIA headers from the
> INVITE request
>
> Has somebody a solution for this problem?

Hello Artur,

you can use a regexp to store the VIAs headers from the invite,
provided that you know which header comes next. Example, with next
header being a From:
  <recv request=3D"INVITE" crlf=3D"true">
     <action>
     <ereg regexp=3D"Via:(.*)From:"
           search_in=3D"msg"
           check_it=3D"true"
           assign_to=3D"1,2" />
     </action>
  </recv>

Variable 1 contains the entire Via....From matching regexp. Variable 2
contains only the expression in parenthesis. This is known as
"sub-expressions" (see
http://sipp.sourceforge.net/doc1.1/reference.html#action_regexp)

Then, you re-use the content of variable [$2] when sending the BYE.
Note that CRs are still there, so you will have to concatenate [$2]
and the next line, like this:

      Via:[$2]Contact: <sip:[local_ip]:[local_port];transport=3D[transport]=
>
      Content-Length: 0

Let us know if it works,
Olivier.