Have libpaf connect to all addresses of DNS-based address

[m-ronnblom]

For TLS or TCP type server addresses, libpaf should resolve the DNS name and connect to all IPv4 and IPv6 addresses, treating each A och AAA record as a separate server.

Current libpaf relies on XCM for name resolution, which in turn relies on glibc and the system's configuration, and picks one addresses out of those available for a particular DNS FQDN.

Considering the change in semantics, this new behavior should only be exhibited if it is explicitly enabled (in the domains file).

[m-ronnblom]

The use-all-DNS-FQDN-IPs would lead to the same credentials (cert, key, and trusted CA bundle) to be used for all servers under a particular DNS name.

[m-ronnblom]

Should there be a way to handle multi-homed servers residing behind the same DNS FQDN?

[m-ronnblom]

libpaf would need to poll DNS to see if the number or contents of records for a particular domain changes. In essence, the DNS hostname will provide the same information as are in the domain file (i.e., a list of server addresses. but minus "extra" such as tlsCertificateFile).

Polling frequency should be determined by the DNS TTL.