Implement DNS SRV failover

Our DNS SRV failover support is only limited to TCP (or TLS) connect failure, which in this case pjsip will automatically retries the next server. But even then, there is no mechanism to flag that a server has been failing, which means that the next request may try the same server again and triggering the failover again.

What we’ve been suggesting is to implement the failover mechanism in the application layer. In this case, the application queries the list of available servers either with gethostbyname, DNS SRV, or by other means. It then specifies which server to use by putting the IP address as proxy parameter (i.e. Route header) in the account config. The mechanism to test the wellness of a server and when to initiate the failover is totally controlled by the application. The application can change which server to use by changing the account proxy setting with pjsua_acc_modify().