[SR-Users] To Header Manipulation

[Daniel-Constantin Mierla]

Hello,

change operations over parts of sip headers are not simple "set"
operations, see these FAQ items for a better understanding of what
happens there:

  *
https://www.kamailio.org/wiki/tutorials/faq/main#why_changes_made_to_headers_or
  *
https://www.kamailio.org/wiki/tutorials/faq/main#why_parts_of_fromto_header_app

I just added the second one to be more focused on this specific case.

Cheers,
Daniel

On 14.10.20 21:00, Sam Ware wrote:
> Wondering if this is intended behavior.  We have a customer doing some
> craziness with the TO header.  They are including their tech prefix in
> the TO header as well as the RURI.  It doesn't cause any issue in our
> systems but apparently it does with one of our vendors.  In an effect
> to prevent the issue, we thought we would check if the tech prefix was
> added on the TO header and remove it.  
>
> Initially, I tried this by changing the $tU variable.  
>
>     $avp(tp_len) = $(avp(techprefix){s.len}) + 1; # Get the Length of
>     the Tech Prefix and add 1 for the # or *
>     $tU = $(tU{s.strip, $avp(tp_len)});
>
>
> The result ended up with the duplication of the DNIS: sut
> <sip:911999#1812555111118125551111 at 172.16.3.45:5060
> <http://1812555111118125551111@172.16.3.45:5060>>
> Where 911999# was the tech prefix and 18125551111 is the DNIS which
> was still an issue for the vendor.
>
> Through additional reading, I found the suggestion to use
> the uac_replace_to function in the UAC module which I implemented as
> follows:
>
>     $avp(new_to_hdr_uri) = $(tu{re.subst,/sip:(.*[\*#])(.*)/sip:\2/});
>     uac_replace_to("$avp(new_to_hdr_uri)");
>
>
> This resulted in the original TO header username to be appended at the
> end of the uri: sut
> <sip:18125551111 at 172.16.3.45:5060911999#18125551111
> <http://sip:18125551111@172.16.3.45:5060911999#18125551111>>
>
> Wondering if I am doing something wrong or this is the way these
> functions are designed to protect the TO header contents for Dialog
> matching.
>
>
> -- 
> Sam  D Ware
>
>
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-- 
Daniel-Constantin Mierla -- www.asipto.com
www.twitter.com/miconda -- www.linkedin.com/in/miconda
Funding: https://www.paypal.me/dcmierla

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