[SR-Users] add_contact_alias and handle_ruri_alias vs fix_nated_contact

[Klaus Darilion]

On 16.03.2012 17:14, yufei.tao wrote:
> Hi
>
> I have been using fix_nated_register/fix_nated_contact for NAT traversal
> and all worked fine. I've come across add_contact_alias and
> handle_ruri_alias:
> http://sip-router.org/wiki/tutorials/alias-example
> where it says:
>
> "The benefits of using add_contact_alias() and handle_ruri_alias()
> functions instead of conventional NAT traversal solutions are:
>
>   *
>     Request-URI in requests to UAs behind NATs is always what UAs expect
>   *
>     Re-use of tcp/tls sessions between proxy and UAs
>
> "
> I assumed the 'conventional NAT traversal solution' here means
> fix_nated_contact?

yes

> I understand the first point, in that the R-URI always contains what the
> client puts in the contact hf.

yes

> But for the second point, about tcp/tls reuse, does fix_nated_contact do
> the same trick, or does add_contact_alias and handle_ruri_alias give you
> more benefit over fix_nated_contact? So far I feel they achieve the same
> thing but would like this confirmed/corrected.

They achieve both the same. I don't remember the problems anymore which 
caused add_contact_alias() to be implemented. IIRC I think it was that 
some clients did not put "transport=tcp" into the Contact header and 
thus the fix_anted_contact missed the transport - add_contact_alias 
always adds the transport protocol. But that is just a guess, I may be 
wrong.

klaus