Description of problem:


systemd-resolve 10.0.0.1

returns long hosts names with the exception of the nodes own ip address
which returns a short hostname.

Version-Release number of selected component (if applicable):

systemd-239-48.el8.x86_64

How reproducible:

Every time

Steps to Reproduce:
1.  systemctl start systemd-resolved
2.  systemd-resolve $(hostname -i)


Actual results:

A short hostname is returned e.g 'bag8' 


2002:1448:d10:3f::100:3c4%eth0: bag8

-- Information acquired via protocol LLMNR/IPv6 in 1.8ms.
-- Data is authenticated: yes
187.184.84.112%eth0: bag8

-- Information acquired via protocol LLMNR/IPv4 in 762us.
-- Data is authenticated: yes



Expected results:

The long hostname is returned e.g. 'bag8.mydomain'


Additional info:

As commented this is only for the ip of the machine. When you run it
the lookup for any other ip address in the world including machines
in the same dns domain then the long name is returned.

This results in weirdness like this in python for instance.

python 3.6.8 (default, May  8 2021, 09:11:34) 
[GCC 8.4.1 20210423 (Red Hat 8.4.1-2)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import socket
>>> socket.getfqdn()
'bag8'
>>> socket.gethostname()
'bag8.mydomain'


For completeness on this node

hostname 

is returning the full name.

I also tested a fedora rawhide node and this does behave itself
so I assume something fixed in systemd at some point.

Below full names are returned.


[root@rawhide ~]# systemd-resolve $(hostname -i)
fe80::f816:3eff:feb3:2db9%2: rawhide.mydomain.ch   -- link: eth0
                             rawhide           -- link: eth0
                             rawhide.local     -- link: eth0

-- Information acquired via protocol DNS in 118.3ms.
-- Data is authenticated: yes; Data was acquired via local or encrypted transport: yes                                                          
-- Data from: synthetic
2002:1558:d01:59::100:22c: rawhide.ipv6.mydomain.ch -- link: eth0

-- Information acquired via protocol DNS in 1.4ms.
-- Data is authenticated: no; Data was acquired via local or encrypted transport: no                                                            
-- Data from: network
188.18.121.31: rawhide.mydomain.ch                -- link: eth0

-- Information acquired via protocol DNS in 990us.
-- Data is authenticated: no; Data was acquired via local or encrypted transport: no                                                            
-- Data from: network