Fix health-check listener monitor to accommodate the default 0.0.0.0 address

[uhppoted]

Ref. uhppoted/uhppoted#14

The health check listener address monitor checks the device listener address against the configured system listener address which fails when the configured listener address is set to the default ALL address (0.0.0.0):

		if !expected.IP.Equal(address.IP) || (expected.Port != address.Port) {
                   ...
               }

(cf. healthcheck.go:L385)

With the default 0.0.0.0 address, the 'expected' health address check should match against at least:

• 127.0.0.1
• the public IPv4 address
• (optionally) a configured address

Notes

1. Ideally the health check should verify that the IP address to which the system event listener is bound is reachable via the controller's configured listener address.

[uhppoted]

Reworked health check to match controller listen address against all IPv4 addresses exposed by the installed network interfaces when the listen address is INADDR_ANY (0.0.0.0). Provisionally excludes the loopback address (127.0.0.1) on the grounds that the loopback address is probably only used by simulated devices.

Tested on MacOS and Ubuntu 22.04LTS.

[uhppoted]

Fixed in release v0.8.1

[uhppoted]

Ref. uhppoted/uhppoted#14 (reply in thread)

netip.AddrFromSlice is prefixing an IPv4 address with :ffff::

2022/08/03 10:14:19 WARN  UTC0311-L0x 201020304  incorrect listener address/port: 192.168.1.100:60001
>>>>>>>> [192.168.1.100:60001]
>>>>>>>> DEBUG true ::ffff:192.168.1.100 60001
2022/08/03 10:14:19 WARN  UTC0311-L0x 303986753  incorrect listener address/port: 192.168.1.100:60001
```

Explicitly convert address to an IPv4 address before checking.

[twystd]

May possibly be related to changes in the netip package:

• net: UDPAddr's (and possibly TCPAddr's) AddrPort returns addresses with the wrong IP version

[twystd]

Explicitly converted IP addresses to IPv4 addresses in the health check. Pending confirmation and release (and unit test).

[uhppoted]

Closing - release in v0.8.2