fix ping tests on unsupported unix platforms

[wfurt]

This is recent regression I bump to while running tests on FreeBSD.

#64625 assumes we would use ping utility only on Linux.
But that is how it works on pretty much on all UNIX like systems and macOS(like) is rare and recent exception.
(event if the list of actual variations is annoyingly long)

This PR generally flips the condition and it assumes we would use ping unless we know we don't have to.
That should make it work again for Solaris(like) and (Free)BSD(like) OSes.

cc: @am11 @Thefrank

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Issue Details

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This is recent regression I bump to while running tests on FreeBSD.

#64625 assumes we would use ping utility only on Linux.
But that is how it works on pretty much on all UNIX like systems and macOS(like) is rare and recent exception.
(event if the list of actual variations is annoyingly long)

This PR generally flips the condition and it assumes we would use ping unless we know we don't have to.
That should make it work again for Solaris(like) and (Free)BSD(like) OSes.

cc: @am11 @Thefrank

Author:	wfurt
Assignees:	wfurt
Labels:	area-System.Net, os-freebsd
Milestone:	-

[am11]

@wfurt, some network areas are quite involved and I didn't had enough time, so I previously asked community (#illumos channel on IRC) for help to port System.Net.* namespaces. The difference in /proc (we rely on procfs heavily for network statistics) alone is quite significant: on Linux it has text files that we conveniently read with System.IO.File.ReadAllLines/Text etc., whereas on illumos/Solaris it has binary files that requires read(struct)), so it is a large workitem for someone well-familiar with low-level networking APIs (that's not me 🙂).
Currently, only System.Runtime, corelib etc. works on illumos.

However, for ping utility, the manpage https://illumos.org/man/1m/ping says there are two forms. The first form supports timeout but not the count (npackets). The second form supports vice versa (uses default timeout of 20 sec). -c is traffic class, different than other Unices where it means count. e.g.

# First form: with default (1 sec)  timeout. simple "alive or not" reply
$ ping github.com

# First form: with specified timeout of 8 seconds
$ ping github.com 8

# Second form: send indefinite number of packets, with ttl 2 intervals
#         (default interval is 1 sec, can be set with -I with min value 0.011 sec):
#         (default size is 56 bytes and shown in output as 64 (56+8)):
$ ping -s -t 20 github.com

# Second form: send 4 packets of size 40 bytes (32 +8 which it will add), with minimum interval 0.011 sec:
$ ping -s -t 20 -I 0.011 github.com 32 4

Capability.CanUseRawSockets(TestSettings.GetLocalIPAddress().AddressFamily);

I think once System.Net is ported to illumos/Solaris, with capabilities queries, this path will work as well.

[rzikm]

LGTM

[Thefrank]

LGTM.
This should be fine for now for what is currently un/supported, but as it was noted, this can get messy fast with all the different variations out there and their differing handling.

[wfurt]

thanks for update @am11. When the time comes we may have more updates in production code that handles arguments.
This was really meant as test fix to sync up with reality. Since we don't have CI it is easy to miss the work-in-progress platforms.