Record-Route not added by proxy in DNS target > 1

[akafazov]

When OverSIP makes DNS based load balancing to route traffic to two or more SIP proxies, the Record-Route header is added only when forwarding to the first DNS target, but not to any of the subsequent ones. This might lead to incorrect routes in SUBSCRIBE/NOTIFY scenarios, so that NOTIFY requests are not being routed to the client.

In our case we have OverSIP taking WSS traffic and forwarding it to two SIP proxies. The IPs of the SIP proxies are resolved by DNS.
If one of the SIP proxies behind OverSIP is offline, SIP REGISTER is sent 4 times to the first target (DNS IP has 2 targets for the hostname) and the 5th REGISTER goes to the SIP proxy that is online. In this case the subsequent SUBSCRIBE messages do not have the Record-Route headers added to them, which leads to incorrect routing for the following NOTIFYs.

[ibc]

Thanks for the report. Let me please some days until I can get deeper into this.

[ibc]

May you please show which kind of DNS entries produces the issue? Are they NAPTR? SRV? both?

[ibc]

If it's possible for you, please try commenting lines from 444 to 449 here:

https://github.com/versatica/OverSIP/blob/master/lib/oversip/sip/client_transaction.rb#L444