For posterity and to help other people since this doesnt appear to be common request, this is what i did to get it working.  Basically, i switched to using uac_redirect.so module, save the headers returned from the 300 reply, and then send new invite with those headers using get_redirects().

# Manage incoming replies in transaction context

onreply_route[MANAGE_REPLY] {

    xdbg("DBG: incoming reply\n");

    if(status=~"[12][0-9][0-9]") {

        route(NATMANAGE);

    }

    if (t_check_status("3[0-9][0-9]")) {

        xlog("L_INFO", "DBG: got 3xx redirect");

        # grab the header from the 300 redirect and save it to add to invite

        $shv(identity) = $hdr(Identity);

        xlog("L_INFO","DBG: manage_reply: redirect identity: [$shv(identity)]");

    }

    return;

}

# Manage failure routing cases

failure_route[MANAGE_FAILURE] {

    route(NATMANAGE);

    if (t_is_canceled()) exit;

    if (t_check_status("3[0-9][0-9]")) {

        xlog("L_INFO", "DBG: following 3xx redirect");

        xlog("L_INFO","DBG: manage_failure: redirect identity: [$shv(identity)]");

        # add the saved header onto the new invite(s) being sent out

        append_hf("Identity: $shv(identity)\r\n");

        get_redirects("*:1");

        route(RELAY);

        exit;

    }

    return;

}

Rob Green​​​​ Chief Information Officer (CIO)

Tel:  1-352-218-1490 Cell:  1-407-620-0932 Email:  rob.green@nuwave.com Web:  www.nuwave.com

This communication is the Property of NUWAVE Communications and may contain confidential or privileged information. Unauthorized use of this communication is strictly prohibited and may be unlawful. If you have received this communication in Error, Please immediately notify the sender by reply e-mail and destroy all copies of the communication and any attachments.

---

From: Rob Green via sr-users <sr-users@lists.kamailio.org>
Sent: Friday, June 7, 2024 7:47 PM
To: sr-users@lists.kamailio.org <sr-users@lists.kamailio.org>
Cc: Rob Green <rob.green@nuwave.com>
Subject: [SR-Users] handling 300 redirect requests

 

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I am trying to proxy a request from server A to server C with me being server B.  i send the invite from A to B, then i need to send to server R which returns back to me a 300 redirect, which i then need to take the answer from the Contsct and then proxy the original invite from A to C.  server A can not handle 3xx responses and must be proxied.  I havent been able to find any examples where the 300 is intercepted and a new invite to the target is sent.  i have the following code but it results in no new INVITE and the original session is hung until it is canceled.    Any idea what i may be doing wrong?  In the example below i am just hardcoding the uri for the new invite instead of getting from the Contact as a debug exercise.  I am using Kamailio 5.7.3

route[HANDLEREDIRECT] {

    xlog("L_INFO", "DBG: HANDLEREDIRECT");

      msg_apply_changes();

      $var(test) = $hdr(Contact);

    xlog("L_INFO","DBG: redirect headers  [$var(test)]: from=[$fu] from_user=[$fU], to=[$tu] to_user=[$tU]");

      # send to gateway

    $var(new_uri) = "sip:" + $tU + "@" + "gateway";

    if ($var(new_uri) != "") {

        xlog("DBG: Redirecting to: $var(new_uri)\n");

        $ru = $var(new_uri);

   $tu = $ru;

     record_route();

  route(RELAY);

     exit;

# i have also tried using 

   #t_newtran();

# and

   #t_relay();

    } else {

        xlog("DBG: No contact header found in 300 response\n");

    }

}

# Manage outgoing branches

branch_route[MANAGE_BRANCH] {

    xdbg("DBG: new branch [$T_branch_idx] to $ru\n");

        xlog("L_INFO", "DBG: manage branch");

    route(NATMANAGE);

    return;

}

onreply_route[MANAGE_REPLY] {

    xdbg("DBG: incoming reply\n");

    xlog("L_INFO", "DBG: manage reply");

    if (t_check_status("3[0-9][0-9]")) {

        xlog("L_INFO", "DBG: got 3xx redirect");

        route(HANDLEREDIRECT);

        drop;

    }

    return;

}

I also tried using uac_redirect module, but it stalls the incoming invite also, and i cant figure out how to modify the uri from the contact before sending (to add params)

# Manage failure routing cases

failure_route[MANAGE_FAILURE] {

    route(NATMANAGE);

    if (t_is_canceled()) exit;

     if (t_check_status("3[0-9][0-9]")) {

          xlog("L_INFO", "DBG: following 3xx redirect");

       get_redirects("3:1");

       t_relay();

       exit;

     }

}

Rob Green​​​​ Chief Information Officer (CIO)

Tel:  1-352-218-1490 Cell:  1-407-620-0932 Email:  rob.green@nuwave.com Web:  www.nuwave.com

This communication is the Property of NUWAVE Communications and may contain confidential or privileged information. Unauthorized use of this communication is strictly prohibited and may be unlawful. If you have received this communication in Error, Please immediately notify the sender by reply e-mail and destroy all copies of the communication and any attachments.

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