[Users] OpenSER as a Load Balancer for Asterisk and RE-INVITEs
Christian Schlatter
cs at unc.edu
Sun Mar 25 20:46:31 CEST 2007
Edoardo Serra wrote:
> Hi all,
> I have an OpenSER acting as a registrar server and as a load
> balancer (with dispatcher module) for a cluster of PSTN Gateways based
> on Asterisk.
>
> When an inbound call is coming from the PSTN, Asterisks dial
> SIP/user at openser and the call is properly forwarded to the correct user
> in OpenSER location table
>
> But, if the user wants, for example, to put the call On-Hold, its user
> agent sends a RE-INVITE to OpenSER.
> My problem is that OpenSER (correctly) dispatch the call to a random
> Asterisk GW, and, if it's not the GW which is handling the call, On-Hold
> does not work and another call is originated.
The call hold RE-INVITE issued by the called UA should include an R-URI
including the contact address of the GW who initiated the SIP call. So
if a call comes from asterisk.1 the RE-INVITE should include a R-URI
like "INVITE sip:ip.of.asterisk.1" (depending of what asterisk.1 puts in
its contact header).
In your script you always call ds_select_dst and the RE-INVITEs get
routed to a destination from the dispatcher destination set instead of
using the R-URI to route the call to the correct GW.
Since you record route each request you could test if the following works:
> # loose-route processing
> if (loose_route()) {
> # mark routing logic in request
> append_hf("P-hint: rr-enforced\r\n");
>
> # don't do ds_select_dst here since the R-URI
> # of RE-INVITEs should
> # contain the correct GW address
> t_relay();
> exit;
> };
Christian
>
> Tnx in advance for help
>
> Edoardo
>
> My openser.cfg follows
>
> # $Id: ser.cfg,v 1.21.4.1 2003/11/10 15:35:15 andrei Exp $
> # ----------- global configuration parameters ------------------------
>
> check_via=yes # (cmd. line: -v)
> dns=no # (cmd. line: -r)
> rev_dns=no # (cmd. line: -R)
> fifo="/tmp/ser_fifo"
>
> #uid=nobody
> #gid=nobody
>
> # ------------------ module loading ----------------------------------
> loadmodule "/usr/lib/openser/modules/sl.so"
> loadmodule "/usr/lib/openser/modules/tm.so"
> loadmodule "/usr/lib/openser/modules/rr.so"
> loadmodule "/usr/lib/openser/modules/maxfwd.so"
> loadmodule "/usr/lib/openser/modules/usrloc.so"
> loadmodule "/usr/lib/openser/modules/registrar.so"
> loadmodule "/usr/lib/openser/modules/nathelper.so"
> loadmodule "/usr/lib/openser/modules/textops.so"
> loadmodule "/usr/lib/openser/modules/exec.so"
> loadmodule "/usr/lib/openser/modules/uri.so"
> loadmodule "/usr/lib/openser/modules/uri_db.so"
> loadmodule "/usr/lib/openser/modules/dispatcher.so"
> loadmodule "/usr/lib/openser/modules/mysql.so"
> loadmodule "/usr/lib/openser/modules/auth.so"
> loadmodule "/usr/lib/openser/modules/auth_db.so"
>
> modparam("usrloc", "db_mode", 2)
> modparam("usrloc", "db_url", "mysql://user:pass@192.168.252.5/openser")
> modparam("usrloc", "timer_interval", 120)
> modparam("auth_db", "calculate_ha1", 0)
> modparam("auth_db", "db_url", "mysql://user:pass@192.168.252.5/db")
> modparam("uri_db", "db_url", "mysql://user:pass@192.168.252.5/openser")
> modparam("rr", "enable_full_lr", 1)
> modparam("registrar", "nat_flag", 6)
> modparam("registrar", "max_expires", 3600)
> modparam("registrar", "min_expires", 60)
> modparam("registrar", "append_branches", 0)
> modparam("registrar", "desc_time_order", 1)
> modparam("nathelper", "natping_interval", 20) # Ping interval 20 s
> modparam("nathelper", "ping_nated_only", 1) # Ping only clients behind
> NAT
> modparam("dispatcher", "force_dst", 1)
>
> # ------------------------- request routing logic -------------------
> # main routing logic
>
> route{
> if (!mf_process_maxfwd_header("10")) {
> sl_send_reply("483","Too Many Hops");
> exit;
> };
> if ( msg:len > max_len ) {
> sl_send_reply("513", "Message too big");
> exit;
> };
>
> if ( (method=="OPTIONS") || (method=="SUBSCRIBE") ||
> (method=="NOTIFY") ) {
> sl_send_reply("405", "Method Not Allowed");
> exit;
> }
>
> if (!method=="REGISTER") {
> record_route();
> };
>
>
> if ((src_ip==ip.of.asterisk.1) || (src_ip==ip.of.asterisk.1)) {
> if (!lookup("location")) {
> sl_send_reply("486", "Busy here");
> exit;
> };
> if (!t_relay()) {
> sl_reply_error();
> };
> exit;
> };
>
> if (nat_uac_test("3")) {
> if ((method=="REGISTER") || (method=="INVITE") ||
> (method=="OPTIONS")) {
> fix_nated_contact();
> force_rport();
> setflag(6); # Mark as NATed
> }
> }
>
> if (method=="REGISTER") {
> if (!proxy_authorize("exorsa", "openser_view")) {
> proxy_challenge("exorsa", "0");
> exit;
> }
> if (!check_to()) {
> sl_send_reply("403", "Digest username and URI
> username do NOT match! Stay away!");
> exit;
> }
>
> save("location");
>
> exit;
> };
>
>
> if (method=="INVITE") {
> if (!proxy_authorize("exorsa", "openser_view")) {
> proxy_challenge("exorsa", "0");
> exit;
> }
>
> if (!check_from()) {
> sl_send_reply("403", "Digest username and URI username do
> NOT match! Stay away!");
> exit;
> }
> }
>
> # loose-route processing
> if (loose_route()) {
> # mark routing logic in request
> append_hf("P-hint: rr-enforced\r\n");
> route(1);
> exit;
> };
>
> if (!uri==myself) {
> # mark routing logic in request
> append_hf("P-hint: outbound\r\n");
> route(1);
> exit;
> };
>
> append_hf("P-hint: usrloc applied\r\n");
> route(1);
> }
>
> route[1]
> {
> # !! Nathelper
> if (uri=~"[@:](192\.168\.|10\.|172\.(1[6-9]|2[0-9]|3[0-1])\.)"
> && !search("^Route:")){
> sl_send_reply("479", "We don't forward to private IP
> addresses");
> exit;
> };
>
> # NAT processing of replies; apply to all transactions (for
> example,
> # re-INVITEs from public to private UA are hard to identify as
> # NATed at the moment of request processing); look at replies
> t_on_reply("1");
>
> if ((src_ip!=ip.of.asterisk.1) && (src_ip!=ip.of.asterisk.2)) {
> ds_select_dst("1", "0");
> }
>
> if (!t_relay()) {
> sl_reply_error();
> };
> }
>
> # !! Nathelper
> onreply_route[1] {
> # NATed transaction ?
> if (isflagset(6) && status =~ "(183)|2[0-9][0-9]") {
> fix_nated_contact();
> # otherwise, is it a transaction behind a NAT and we did not
> # know at time of request processing ? (RFC1918 contacts)
> } else if (nat_uac_test("1")) {
> fix_nated_contact();
> };
> }
>
>
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