[SR-Users] Redirects - are q values required to implement serial forking?

[Brandon Armstead]

Mike,

    Your likely running into an issue where your changes are not actually
applied.  Check out msg_apply_changes() or something of the such.

On Mon, Nov 12, 2018 at 6:52 AM Mike Montgomery <mmontgomery at trust-tek.com>
wrote:

> We have a situation where we get a redirect from a carrier with a list of
> carriers to send the transaction to in the contact header. None of the
> carriers in the contact header have q values assigned.
>
> We have implemented our redirect handling logic using the UAC_REDIRECT
> module (get_redirects()) with help from TM module (t-load_contacts(),
> t_next_contact()). (failure_route code is at bottom of this note)
>
> We find that when we receive a contact header with q values, we can launch
> requests serially using t_next_contact() and individually work through the
> contact list until we get a positive response. When we get a redirect with
> no q values in the contact header we find that all contacts get loaded and
> launched in parallel.
>
> Although not stated in the documentation, it appears that in order to
> implement serial contact redirect handling, q values must be present in the
> contact header. Based on this assumption, and knowing that the redirecting
> carrier cannot include q values, we have attempted to modify the contact
> header and find that we are unable to add q values to the contact header.
>
> We have attempted without success to use remove_hf("Contact”) followed
> by append_hf("Contact: $(avp(contact)) \r\n”); where $(avp(contact)) is the
> avp where we have rewritten the contact header to include q values.
>
> Any guidance on how to handle this issue is appreciated.
>
> _________________________________________________________-
>
> Our failure route code:
>         if (t_check_status("3[0-9][0-9]")) {
>                 xlog("L_INFO", "----> REDIRECT Contact Header -->
> $T_rpl($ct) --- Method $rm --- From $T_req($fu) --- To $T_req($tu) ---
> Destination $T_req($du) \n");
>                 get_redirects("*:*");
>
>                 if (!t_load_contacts()) {
>                         xlog("L_INFO", "-t_load_contacts() FAILED /n");
>                 };
>
>                         xlog("L_INFO", "####->LOAD CONTACT LIST
> $xavp(tm_contacts[0]=>uri) \n");
>
>                 if (t_next_contacts()) {
>                         xlog("L_INFO", "-t_next_contact() loaded
> successfully /n");
>                         xlog("L_INFO", "####-> NEXT CONTACT LIST
> $xavp(tm_contacts[0]=>uri) \n");
>                 };
>                 t_on_failure("serial");
>
>                 if(t_relay()){
>                     xlog("L_INFO","----->Relayed in MANAGE_FAILURE ---
> Method $rm --- Contact Header $ct \n");
>                  };
>                 exit;
>         } else {
>                 xlog("L_INFO","-----> NO REDIRECT --- Method $rm ---
> Contact Header $ct \n");
>                 exit;
>         }
>
> failure_route["serial"] {
>         xlog ("L_INFO", "Entered failure_route(serial) /n");
>         if (t_check_status("3[0-9][0-9]")) {
>                 xlog("L_INFO", "----> DOUBLE REDIRECT Contact Header -->
> $T_rpl($ct) --- Method $rm --- From $T_req($fu) --- To $T_req($tu) ---
> Destination $T_req($du) \n");
>                 $xavp(tm_contacts[*]) = $null;
>                 xlog("L_INFO", "XXX-> tm_contacts reset to Null
> $xavp(tm_contacts[0]=>uri)\n");
>
>                 get_redirects("*:*");
>
>                 if (!t_load_contacts()) {
>                         xlog("L_INFO", "-t_load_contacts() FAILED /n");
>                 };
>
>                         xlog("L_INFO", "####-> LOAD 2 CONTACT LIST
> $xavp(tm_contacts[0]=>uri) \n");
>
>         }
>         if (!t_next_contacts()) {
>                 exit;
>         }
>
>         xlog("L_INFO", "-t_next_contact() loaded successfully /n");
>         xlog("L_INFO", "####-> NEXT CONTACT LIST
> $xavp(tm_contacts[0]=>uri) \n");
>
>         t_on_failure("serial");
>         if(t_relay()){
>             xlog("L_INFO","----->Relayed in failure_route(serial) ---
> Method $rm --- Contact Header $ct \n");
>         };
> }
>
> Best Regards,
>
>  Mike Montgomery
>  Principal, Trusted Technical Services, Inc.
>  o - 919 924 4703  x3000
>  m - 919 539 6133
>
>
> _______________________________________________
> Kamailio (SER) - Users Mailing List
> sr-users at lists.kamailio.org
> https://lists.kamailio.org/cgi-bin/mailman/listinfo/sr-users
>
-- 
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