op-mode: T6626: Fix for show dhcpv6 server leases

[natali-rs1985]

Change Summary

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Code style update (formatting, renaming)
• Refactoring (no functional changes)
• Migration from an old Vyatta component to vyos-1x, please link to related PR inside obsoleted component
• Other (please describe):

Related Task(s)

• https://vyos.dev/T6626

Related PR(s)

Component(s) name

op-mode

Proposed changes

How to test

vyos@vyos# cat /config/dhcpdv6.leases
# The format of this file is documented in the dhcpd.leases(5) manual page.
# This lease file was written by isc-dhcp-4.4.3-P1

# authoring-byte-order entry is generated, DO NOT DELETE
authoring-byte-order little-endian;

server-duid "\000\001\000\001.>X\261\014\337l\370\000\001";

ia-pd "\036\000\000\000\000\0048\202l\266\345\257IJ\236c\245\212\000\204D\014" {
  cltt 4 2024/09/13 14:38:45;
  iaprefix 2001:db8:1:ffe0::/60 {
    binding state active;
    preferred-life 4294967295;
    max-life 4294967295;
    ends never;
    set shared-networkname = "LAN";
  }
}

server-duid "\000\001\000\001.>X\261\014\337l\370\000\001";

ia-pd "\036\000\000\000\000\0048\202l\266\345\257IJ\236c\245\212\000\204D\014" {
  cltt 4 2024/09/13 14:55:43;
  iaprefix 2001:db8:1:ffe0::/60 {
    binding state released;
    preferred-life 4294967295;
    max-life 4294967295;
    ends never;
  }
}

ia-pd "\036\000\000\000\000\0048\202l\266\345\257IJ\236c\245\212\000\204D\014" {
  cltt 4 2024/09/13 14:56:08;
  iaprefix 2001:db8:1:fff0::/60 {
    binding state active;
    preferred-life 4294967295;
    max-life 4294967295;
    ends never;
    set shared-networkname = "LAN";
  }
}

ia-na "\334\005\2750\000\004\004\360.\224\341h\033#\243\261d\344'\275b6" {
  cltt 5 2024/09/13 14:22:18;
  iaaddr fd00::1:0:0:ffff:b1d9 {
    binding state active;
    preferred-life 7200;
    max-life 7500;
    ends 5 2024/09/13 16:27:18;
  }
}

Before the fix:

vyos@vyos:~$ show dhcpv6 server leases 
Traceback (most recent call last):
  File "/usr/libexec/vyos/op_mode/dhcp.py", line 438, in <module>
    res = vyos.opmode.run(sys.modules[__name__])
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3/dist-packages/vyos/opmode.py", line 263, in run
    res = func(**args)
          ^^^^^^^^^^^^
  File "/usr/libexec/vyos/op_mode/dhcp.py", line 265, in _wrapper
    return func(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^
  File "/usr/libexec/vyos/op_mode/dhcp.py", line 322, in show_server_leases
    return _get_formatted_server_leases(lease_data, family=family)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/libexec/vyos/op_mode/dhcp.py", line 175, in _get_formatted_server_leases
    end =  _utc_to_local(end).strftime('%Y/%m/%d %H:%M:%S')
           ^^^^^^^^^^^^^^^^^^
  File "/usr/libexec/vyos/op_mode/dhcp.py", line 47, in _utc_to_local
    return datetime.fromtimestamp((datetime.fromtimestamp(utc_dt) - datetime(1970, 1, 1)).total_seconds())
                                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
TypeError: 'NoneType' object cannot be interpreted as an integer

After the fix:

vyos@vyos# run show dhcpv6 server leases
IPv6 address           State     Last communication    Lease expiration     Remaining    Type               Pool    DUID
---------------------  --------  --------------------  -------------------  -----------  -----------------  ------  -----------------------------------------------------
2001:db8:1:ffe0::/60   released  2024/09/13 14:55:43   -                    -            prefix delegation          00:04:38:82:6c:b6:e5:af:49:4a:9e:63:a5:8a:00:84:44:0c
2001:db8:1:fff0::/60   active    2024/09/13 14:56:08   -                    -            prefix delegation  LAN     00:04:38:82:6c:b6:e5:af:49:4a:9e:63:a5:8a:00:84:44:0c
fd00::1:0:0:ffff:b1d9  active    2024/09/13 14:22:18   2024/09/13 16:27:18  2:54:36      non-temporary              00:04:04:f0:2e:94:e1:68:1b:23:a3:b1:64:e4:27:bd:62:36
[edit]

Smoketest result

Checklist:

• I have read the CONTRIBUTING document
• I have linked this PR to one or more Phabricator Task(s)
• I have run the components SMOKETESTS if applicable
• My commit headlines contain a valid Task id
• My change requires a change to the documentation
• I have updated the documentation accordingly

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