Fetching FQDN?

[jszwedko]

Thanks for this crate!

I was just wondering what you thought about adding a mechanism to fetch the fully qualified domain name (similar to hostname --fqdn).

[svartalf]

Yeah, it would be nice to have it, but it needs a bit more investigation first how would it work both for Windows and POSIX-compatible systems.

So far it looks like GetComputerNameExW in combination with ComputerNamePhysicalDnsFullyQualified flag can be used for Windows.
As for POSIX, seems like this approach would be our solution.

It sounds promising so far, but it would be better to double check everything first.

[magistau]

I should note that GNU libc apparently returns FQDN for gethostname: https://www.gnu.org/software/libc/manual/html_node/Host-Identification.html. And macOS does that too.
I mean, I stumbled upon this issue while I was searching why a certain Rust utility gives a different hostname from its original bash version which uses scutil.

[pemensik]

Note: hostname -f may not work on many Linux systems, where myhostname nss plugin is used in /etc/nsswitch.conf. If you have it installed and enabled before DNS, it may prevent obtaining FQDN. It just stops search domains appending in DNS. Compare outputs of getent ahosts -s dns $HOSTNAME | head -1 and getent ahosts -s myhostname $HOSTNAME | head -1, when you have relative only hostname set (without dots) and have search domain used in /etc/resolv.conf.

[pemensik]

Unfortunately there does not seem to be good alternative machanism, which would be reliable. At least not simple way of getting this by normal system API.