[SR-Users] UAC authentication challenge response using KEMI/app_ruby

[Andrew White]

Hi all,

I’ve gotten a little closer.

After setting my $avp(arealm) to an empty string, I’ve been able to get a Authorization response sent. It appears that my trunk in this case regularly responds from different realms, which is an issue I’ll have to deal with another time.

Since then, I’m now sending a valid Authorization header back in a second invite, however I’m also sending an identical invite immediately after:

https://i.imgur.com/lmuglwu.png <https://i.imgur.com/lmuglwu.png>

The code block generating this is the same as below, but with the append_branch():

 if KSR::UAC.uac_auth() then
    KSR <http://ksr.info/>.info <http://ksr.info/>("UAC authed, relaying")
    KSR::COREX.append_branch()
    KSR::TM.t_relay()
  else

Removing the t_relay() obviously stops any response at all, and removing the append_branch means only an ACK is sent.

Can anyone point me the right way here?

Thanks!
________________________________

Andrew White - Director
uConnected
Email: andrew at uconnected.com.au <mailto:andrew at uconnected.com.au>
Web: www.uConnected.com.au <http://www.uconnected.com.au/>

> On 5 Apr 2019, at 2:07 pm, Andrew White <andrew at uconnected.com.au> wrote:
> 
> Hi all,
> 
> I’m continuing on my quest to use app_ruby for my logic - it’s working very well so far!
> 
> The last major hurdle I’ve come across is UAC response to WWW challenge. On my outbound path, the correct URIs for From and To are set based on provider requirements, and the INVITE is sent using t_relay():
> 
> def ksr_route_to_trunk()
>   KSR.info("Route to trunk")
>   if KSR::TM.t_is_set("failure_route") < 0 then
>     KSR::TM.t_on_failure("ksr_failure_manage_trunk")
>   end
> 
>   # Relay
>   KSR::PV.sets("$fu", "sip:#{$uacs[trunk]['r_username']}@#{$uacs[trunk]['r_domain']}")
>   KSR::PV.sets("$fn", '')
>   new_uri = "sip:61400123123@ <sip:61400123123@>#{uacs[trunk]['r_domain']}"
>   KSR.info("New URI is #{new_uri}")
> 
>   KSR.seturi(uri)
>   KSR::UAC.uac_replace_to('', uri)
> 
>   KSR::TM.t_relay()
>   exit
> end
> 
> I’ve stripped it back, but this function is great and works perfectly. An INVITE is sent to the correct place, and the trunk receives the INVITE. It then responds with a 401/WWW-Authenticate.
> 
> My failure route is called fine. Below is the stripped down code:
> 
> def ksr_failure_manage_trunk()
>   exit if KSR::TM.t_is_canceled() > 0
>   KSR.info("Hit trunk failure manage route")
>   KSR::PV.sets("$avp(auser)", 'user')
>   KSR::PV.sets("$avp(apass)", 'pass')
>   KSR::PV.sets("$avp(arealm)", 'test.local')
>   KSR.info("AVPs: #{KSR::PV.gete("$avp(auser)")} #{KSR::PV.gete("$avp(apass)")} #{KSR::PV.gete("$avp(arealm)")}")
> 
>   if KSR::UAC.uac_auth() then
>     KSR.info("UAC authed, relaying")
>     KSR::TM.t_relay()
>   else
>     KSR.info("UAC NOT authed, no relay")
>   end
>   exit
> 
> end
> 
> Also the AVP values are set (I believe) correctly:
> 
> modparam("uac", "auth_username_avp", "$avp(auser)")
> modparam("uac", "auth_password_avp", "$avp(apass)")
> modparam("uac", "auth_realm_avp", "$avp(arealm)")
> 
> This throws the following complaint, and doesn’t send a new response back to the trunk:
> 
> Apr  5 02:55:22 ip-10-0-0-2 /usr/local/sbin/kamailio[26870]: ERROR: {1 102 INVITE 3a84da15272da66e527a79144c48516c at 10.0.0.20 <mailto:3a84da15272da66e527a79144c48516c at 10.0.0.20>:5060} tm [t_fwd.c:1728]: t_forward_nonack(): no branches for forwarding
> Apr  5 02:55:22 ip-10-0-0-2 /usr/local/sbin/kamailio[26870]: ERROR: {1 102 INVITE 3a84da15272da66e527a79144c48516c at 10.0.0.20 <mailto:3a84da15272da66e527a79144c48516c at 10.0.0.20>:5060} tm [tm.c:1619]: _w_t_relay_to(): t_forward_noack failed
> 
> I don’t understand branches very well, however after some digging around, I appended KSR::COREX.append_branch() in before the t_relay() in the failure. This stops the error and now we send an ACK and a new INVITE, but still without the expected authorisation header.
> 
> I feel like my lack of understanding about branches is the issue here - I seem to be sending an INVITE, but not adding the auth header that I suspect is being generated somewhere!
> 
> Thanks for your help.
> 
> ________________________________
> 
> Andrew White - Director
> uConnected
> Email: andrew at uconnected.com.au <mailto:andrew at uconnected.com.au>
> Web: www.uConnected.com.au

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