Hi,

You can also inspect the SDP and look for private or public IPs and perform some logic based on that.

sdp_get_line_startswith("$avp(sdp_media_ip)", "c=");

if (is_ip_rfc1918("$(avp(sdp_media_ip){s.select,2, })")) {}

The delimiter for the transformation is an empty space in this case.

Hope this helps.

Regards,

Grant

From: sr-users <sr-users-bounces@lists.kamailio.org> On Behalf Of David Villasmil
Sent: donderdag 21 november 2019 09:38
To: Kamailio (SER) - Users Mailing List <sr-users@lists.kamailio.org>
Subject: Re: [SR-Users] How to retrieve local socket that will be used to send a message from the branch route

[EXTERNAL EMAIL]

Hello,

I'm not sure this is the best or even the right way, but i do that by figuring out where the call is coming from.

In my case, an INVITE from an RFC1918 IP address will always be internal to external and vice versa.

 i.e.:

    # If the Source IP is an RFC1918 address, it's coming from an internal endpoint, so the call is going out
    if (is_ip_rfc1918("$si")) {
        $dlg_var(rtp_direction) = "direction=internal direction=external";
    } else {
        $dlg_var(rtp_direction) = "direction=external direction=internal";
    }

You may even check both origin and destination domain ($du) and configure rtpengine accordingly.

onsend_route {
    xlog("L_ERR", "[onsend_route] Packet going to $du\n" );
    if (is_ip_rfc1918("$si") && is_ip_rfc1918("$du") ) {
        # call is internal to internal 

    } else if (is_ip_rfc1918("$si") && !is_ip_rfc1918("$du")) {
        # call is internal to external 

    } else if (!is_ip_rfc1918("$si") && !is_ip_rfc1918("$du")) {
        # call is external to external 

    } else if (!is_ip_rfc1918("$si") && is_ip_rfc1918("$du")) {
        # call is external to internal
    }
}

Hope that makes sense and help you a little.

Regards,

David Villasmil

email: david.villasmil.work@gmail.com

phone: +34669448337

On Thu, Nov 21, 2019 at 6:11 AM Patrick Wakano <pwakano@gmail.com> wrote:

Hello list,

Hope you are all doing well!

I am trying to figure out a way to retrieve the local socket the t_relay() has decided to use in a mhomed=1 env. Is there a way to do that? I couldn't find any variable other than the $snd ones that maybe have this info, but I am not using onsend_route anyway.....

I am after this value because this is what I can use to figure out if I need to engage RTPEngine with parameters "external, internal", "external, external", "internal, external" or "internal, internal". In my case, my server is in between two networks, and calls can traverse or can be routed back to the same interface depending on what was decide by the LCR module. Signalling is fine, but engaging the RTPEngine must be done with the correct parameters to get the correct IPs in the SDP, other else I get one way audio in the call.....

Any help is much appreciated!

Thank you!

Kind regards,

Patrick Wakano

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