Check 'hostname' instead of 'hostname -s' in sethostname

[tomvil]

Why I did it

I noticed that /etc/hosts file is getting constantly filled with new records when dhclient is enabled.

root@test:~# cat /etc/hosts | wc -l
246

DHCP is providing FQDN, while we check only against short hostname and this will never match.

root@test:~# hostname
test.lab.com
root@test:~# hostname -s
test

And DHCP offer:

root@test:~# tcpdump -i eth0 -n -vv port 67 or port 68
tcpdump: listening on eth0, link-type EN10MB (Ethernet), snapshot length 262144 bytes
...
	    Hostname (12), length 30: "test.lab.com"
...

sethostname6 also uses hostname instead of hostname -s

Work item tracking

• Microsoft ADO (number only):

How I did it

I changed current_host_name variable to be hostname value instead of hostname -s

How to verify it

• Enable DHCP client on the switch
• Receive offer with FQDN hostname option
• Without this fix everytime new entry will be added to /etc/hosts
• With this fix no new entry will be added

Which release branch to backport (provide reason below if selected)

• 201811
• 201911
• 202006
• 202012
• 202106
• 202111
• 202205
• 202211
• 202305
• 202405

Tested branch (Please provide the tested image version)

202405

Description for the changelog

Change current_host_name value to hostname instead of hostname -s in sethostname file

Link to config_db schema for YANG module changes

A picture of a cute animal (not mandatory but encouraged)

[linux-foundation-easycla]

• ✅login: tomvil / (defe72d)

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