[SR-Users] Add Header

[Daniel Tryba]

On Thursday 27 February 2014 18:06:13 Tony Turner wrote:
> is it possible with Kamailio to have customers calls come in on a trusted
> IP and when they send calls we add a header with a [client id] which we
> can remove on the next ip switch upstream
> 
> So example
> 
> Call comes in from customer with IP:
> their trusted IP source xx.xx.xx.xx
> add header with their client ID

Offcourse this is possible. I do something similar to indicat to upstream sip 
servers the call is accounted for.

I store trusted IPs in the address table and check for INVITES from those IPs. 
If one matches I make a lookup in the usr_preferences table to figure out what 
client it is for:

route[AUTHENTICATE]
{
        if(!is_method("REGISTER") && allow_address("3", "$si", "$sp") && 
$proto=="tcp")
        {
                if(!avp_db_query("select username from usr_preferences where 
attribute='ip_authentication' and (value='$si:$sp' or value like '$si:%') 
order by length(value) limit 1"))
                {
                        sl_send_reply("403", "Not Allowed");
                        exit;
                }

                $avp(au)=$avp(i:1);
        }
        else
        {
                 #normal authentication
...

append_hf() to append a header. Be sure to remove the header from all incoming 
requests first (remove_hf()).

BTW this is insecure for udp traffic. If someone is able to spoof source 
adresses this might be abused, hence the tcp only condition.

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