T5148: Fix OpenVPN plugin dir variable

[sever-sever]

Change Summary

Jinja2 template uses {{ plugin_dir }} that it gets from the interface-openvpn.py variable plugin_dir but the correct var should be as part of 'openvpn' dictionary i.e. openvpn['plugin_dir']

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/T5148

Component(s) name

Proposed changes

How to test

OpenVPN configuration:

set interfaces openvpn vtun10 description 'Server foo'
set interfaces openvpn vtun10 encryption cipher 'aes256'
set interfaces openvpn vtun10 hash 'sha512'
set interfaces openvpn vtun10 local-host '203.0.113.1'
set interfaces openvpn vtun10 local-port '1194'
set interfaces openvpn vtun10 mode 'server'
set interfaces openvpn vtun10 persistent-tunnel
set interfaces openvpn vtun10 protocol 'udp'
set interfaces openvpn vtun10 server client client1 ip '10.10.0.10'
set interfaces openvpn vtun10 server domain-name 'vyos.net'
set interfaces openvpn vtun10 server max-connections '250'
set interfaces openvpn vtun10 server mfa totp
set interfaces openvpn vtun10 server name-server '172.16.254.30'
set interfaces openvpn vtun10 server subnet '10.10.0.0/24'
set interfaces openvpn vtun10 server topology 'subnet'
set interfaces openvpn vtun10 tls ca-certificate 'ca'
set interfaces openvpn vtun10 tls certificate 'cert'
set interfaces openvpn vtun10 tls dh-params 'dh'
set interfaces openvpn vtun10 tls tls-version-min '1.0'

Before fix we get incorrect plugin_path

plugin "/openvpn-otp.so" "otp_secrets=/config/auth/openvpn/vtun10-otp-secrets otp_slop=180 totp_t0=0 totp_step=30 totp_digits=6 password_is_cr=1"

And OpenVPN cannot start:

Apr 10 13:17:38 r14 openvpn-vtun10[13114]: PLUGIN_INIT: could not load plugin shared object /openvpn-otp.so: /openvpn-otp.so: cannot open shared object file: No such file or directory: No such file or directory (errno=2)
Apr 10 13:17:38 r14 openvpn-vtun10[13114]: Exiting due to fatal error
Apr 10 13:17:38 r14 systemd[1]: openvpn@vtun10.service: Main process exited, code=exited, status=1/FAILURE
Apr 10 13:17:38 r14 systemd[1]: openvpn@vtun10.service: Failed with result 'exit-code'.
Apr 10 13:17:38 r14 systemd[1]: Failed to start openvpn@vtun10.service - OpenVPN connection to vtun10

After fix:

plugin "/usr/lib/openvpn/openvpn-otp.so" "otp_secrets=/config/auth/openvpn/vtun10-otp-secrets otp_slop=180 totp_t0=0 totp_step=30 totp_digits=6 password_is_cr=1"

Show interfaces

vyos@r14# run show interfaces openvpn 
Codes: S - State, L - Link, u - Up, D - Down, A - Admin Down
Interface        IP Address                        S/L  Description
---------        ----------                        ---  -----------
vtun10           10.10.0.1/24                      u/u  Server foo

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

[sarthurdev]

We should probably have a smoketest for the OTP plugin too.

[dmbaturin]

@sarthurdev Smoke tests for OTP is a good point indeed.