[sr-dev] [kamailio] missing BYE when 2 redundant kamailio servers share the same database (#110)

[mading087]

Hi, all

I'm trying to set up 2 kamailio servers for active-active redundancy. The two kamailio severs share the the same database with db_mode=3, and no registration replication. Use pjsua2 as SIP client for testing. The test setup is as follows:

kamailio server 1(k1): 10.0.1.30:5061
kamailio server 2(k2): 10.0.1.32:5061
sip client c1: sip:16317 at 10.0.1.30
sip client c2: sip:72316 at 10.0.1.30

c1 is registered with k1.
c2 is registered with k2.

When c1 calls c2, the call flow is as follows:
INVITE:
c1------>k1------>k2------>c2
200 OK:
c1<------k1<------k2<------c2

So far, the INVITE works. c1 and c2 can establish a call. However, when c2 hangs up and sends BYE, the BYE is forwarded all the way to k1, and then k1 gives a 500 server error.
The log on k1 seems to indicate k1 was attempting to create a TLS connection to itself instead of using the existing TLS connection to c1 to forward the BYE.

BYE:
c1       k1<------k2<------c2
           |
           |------->Connection refused/500

Here is the kamailio log on k1:
Mar 16 10:34:21 kamailio.sip.com /usr/sbin/kamailio[13396]: ERROR: <core> [tcp_main.c:2740]: tcpconn_1st_send(): connect 10.0.1.30:55999 failed (RST) Connection refused
Mar 16 10:34:21 kamailio.sip.com /usr/sbin/kamailio[13396]: ERROR: <core> [tcp_main.c:2750]: tcpconn_1st_send(): 10.0.1.30:55999: connect & send  for 0x7fc96a68a1a0 failed: Connection refused (111)

This is the routing logic for BYE in kamailio.cfg:
                if (loose_route()) {
                        route(DLGURI);
                        if (is_method("BYE")) {
                                xlog("L_DBG", "=====BYE $ru from $fu $si:$sp to $du=====\n");
                                dlg_manage();
                                setflag(FLT_ACC); # do accounting ...
                                setflag(FLT_ACCFAILED); # ... even if the transaction fails
                        }
                        else if ( is_method("ACK") ) {
                                # ACK is forwarded statelessy
                                route(NATMANAGE);
                        }
                        else if ( is_method("NOTIFY") ) {
                                # Add Record-Route for in-dialog NOTIFY as per RFC 6665.
                                record_route();
                        }
                        route(RELAY);
                        exit;
                } else {......

If I add location based routing for BYE from peer kamailio, then the BYE seems to be forwarded correctly:
                if (loose_route()) {
                        route(DLGURI);
                        if (is_method("BYE")) {
                                xlog("L_DBG", "=====BYE $ru from $fu $si:$sp to $du=====\n");
                                dlg_manage();
                                setflag(FLT_ACC); # do accounting ...
                                setflag(FLT_ACCFAILED); # ... even if the transaction fails
                                # If BYE coming from Kamailio  peer, route BYE by location
                                $var(peerlist)=$sel(cfg_get.trusted.peers);
                                $var(i) = 0;
                                while($var(i)<$(var(peerlist){param.count})) {
                                        xlog("L_DBG", "=====$(var(peerlist){param.count})=====$(var(peerlist){param.valueat,$var(i)})=====\n");
                                        if(src_ip==$(var(peerlist){param.valueat,$var(i)})) {
                                                lookup("location");
                                                xlog("L_DBG", "=====BYE from $fu $si:$sp to $du=====\n");
                                                break;
                                        }
                                        $var(i) = $var(i) + 1;
                                }
                        }
                        else if ( is_method("ACK") ) {
                                # ACK is forwarded statelessy
                                route(NATMANAGE);
                        }
                        else if ( is_method("NOTIFY") ) {
                                # Add Record-Route for in-dialog NOTIFY as per RFC 6665.
                                record_route();
                        }
                        route(RELAY);
                        exit;
                } else {......

My first question is why k1 loose_route sends the BYE to itself instead of the client. Is this a bug? 
My next question is whether the above location routing for BYE from peer kamailio a good/safe approach.

Thanks


---
Reply to this email directly or view it on GitHub:
https://github.com/kamailio/kamailio/issues/110
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