T6351: CGNAT add verification if the pool exists (backport #3464)

[mergify]

Change Summary

Add verification if the external/internal pools are exists before we can use them in the source and translation rules

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/T6351

Related PR(s)

Component(s) name

cgnat

Proposed changes

How to test

Use not exists pool name in the rules (in this example fake-pool):

set nat cgnat pool external ext1 external-port-range '1024-65535'
set nat cgnat pool external ext1 per-user-limit port '2000'
set nat cgnat pool external ext1 range 192.168.122.222/32
set nat cgnat pool internal int1 range '100.64.0.0/28'

set nat cgnat rule 10 source pool 'fake-pool'
set nat cgnat rule 10 translation pool 'ext1'

Before the fix:

vyos@r4# commit
[ nat cgnat ]
VyOS had an issue completing a command.

Report time:      2024-05-16 15:23:29
Image version:    VyOS 1.5-rolling-202405140019
Release train:    current

Built by:         autobuild@vyos.net
Built on:         Tue 14 May 2024 02:55 UTC
Build UUID:       c30a637d-f3c1-473e-8af6-03c9bfaf0729
Build commit ID:  3463386246a9ac

Architecture:     x86_64
Boot via:         installed image
System type:      KVM guest

Hardware vendor:  QEMU
Hardware model:   Standard PC (Q35 + ICH9, 2009)
Hardware S/N:     
Hardware UUID:    166cfd25-7d3a-4eca-9ef6-0b655c9acf0f

Traceback (most recent call last):
  File "/usr/libexec/vyos/conf_mode/nat_cgnat.py", line 284, in <module>
    generate(c)
  File "/usr/libexec/vyos/conf_mode/nat_cgnat.py", line 240, in generate
    i_count = IPOperations(int_range).get_ips_count()
              ^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/libexec/vyos/conf_mode/nat_cgnat.py", line 39, in __init__
    self.ip_network = ipaddress.ip_network(ip_prefix) if '/' in ip_prefix else None
                                                         ^^^^^^^^^^^^^^^^
TypeError: argument of type 'NoneType' is not iterable



[[nat cgnat]] failed
Commit failed
[edit]
vyos@r4#

After the fix:

vyos@r4# commit
[ nat cgnat ]
Internal pool "fake-pool" does not exist!

[[nat cgnat]] failed
Commit failed
[edit]
vyos@r4# 

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

---

This is an automatic backport of pull request #3464 done by [Mergify](https://mergify.com).

[mergify]

Cherry-pick of c4cee2b has failed:

On branch mergify/bp/sagitta/pr-3464
Your branch is up to date with 'origin/sagitta'.

You are currently cherry-picking commit c4cee2b7c.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Unmerged paths:
  (use "git add/rm <file>..." as appropriate to mark resolution)
	deleted by us:   src/conf_mode/nat_cgnat.py

no changes added to commit (use "git add" and/or "git commit -a")

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

[sever-sever]

We do not have CGNAT for 1.4