op-mode: T3435: Fix SNAT any address and DNAT port dict check

[sever-sever]

Change Summary

Op-mode
If the NAT source address in not exists, use 'any'
Add check if 'port' exists in the dictionary

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://phabricator.vyos.net/T3435

Component(s) name

nat

Proposed changes

How to test

VyOS configuration:

set nat destination rule 120 destination address '203.0.113.1'
set nat destination rule 120 inbound-interface 'eth0'
set nat destination rule 120 protocol 'tcp'
set nat destination rule 120 translation address '192.0.2.40'

set nat source rule 10 description 'Masquerade to NAT'
set nat source rule 10 outbound-interface 'eth0'
set nat source rule 10 translation address 'masquerade'

Before Fix:

vyos@r14:~$ show nat destination rules 
Traceback (most recent call last):
  File "/usr/libexec/vyos/op_mode/show_nat_rules.py", line 102, in <module>
    if isinstance(tran_addr_json['port'],int):
Rule       Destination                                        Translation                                        Inbound Interface
----       -----------                                        -----------                                        -----------------
KeyError: 'port'
vyos@r14:~$

vyos@r14:~$ show nat source rules 
Rule       Source                                             Translation                                        Outbound Interface
----       ------                                             -----------                                        ------------------
Traceback (most recent call last):
  File "/usr/libexec/vyos/op_mode/show_nat_rules.py", line 114, in <module>
    print(format_nat_rule.format(rule, srcdests[0], tran_addr, interface))
IndexError: list index out of range

After fix:

vyos@r14# run show nat destination rules 
Rule       Destination                                        Translation                                        Inbound Interface
----       -----------                                        -----------                                        -----------------
120        tcp                                                192.0.2.40                                         eth0      
           203.0.113.1                                                                                                     
[edit]
vyos@r14# 
[edit]
vyos@r14# run show nat source  rules 
Rule       Source                                             Translation                                        Outbound Interface
----       ------                                             -----------                                        ------------------
10         any                                                masquerade                                         eth0      
[edit]
vyos@r14# 

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