Implement DatagramSocket and friends on Native

[armanbilge]

@lavrov I think you've been waiting for this one 😄 I've published it as 3.8-a43eaac. If you have a chance to try it, please let me know if there are any issues!

It's based on typelevel#3240, but I'll wait to PR it separately because that one is so big already.

[lavrov]

@armanbilge you are right, UDP support is a blocker for one of my projects. This made me follow recent development in polling runtime space and it looks great!

Is this supposed to work on MacOS? I quickly tried your build and got

java.io.IOException: Can't assign requested address
	at java.lang.StackTrace$.currentStackTrace$$anonfun$1(Unknown Source)
	at java.lang.StackTrace$$$Lambda$2.applyVoid(Unknown Source)
	at apply @ fs2.io.net.FdPollingDatagramSocket.write$$anonfun$1(Unknown Source)
	at pollWriteRec @ fs2.io.net.FdPollingDatagramSocket.write(Unknown Source)
	at main @ Main.main(Unknown Source)
	at flatMap @ Main$.run$$anonfun$1(Unknown Source)

UPDATE:
It seems the problem was in a bind address: i had to set it explicitly to ip"0.0.0.0":

Network[IO].openDatagramSocket(Some(ip"0.0.0.0"))

I will give it more extensive testing later on.

[armanbilge]

It seems the problem was in a bind address: i had to set it explicitly to ip"0.0.0.0"

Oh, that's interesting. Thanks for trying that, I will investigate it too.

If bind address is None it should use loopback, maybe that is behaving strangely on macOS 🤔

fs2/io/native/src/main/scala/fs2/io/net/FdPollingDatagramSocketGroup.scala

Line 48 in a43eaac

address <- Resource.eval(address.fold(IpAddress.loopback)(_.resolve))

[lavrov]

If bind address is None it should use loopback, maybe that is behaving strangely on macOS 🤔

JVM version promises binding to "all interfaces".

https://github.com/typelevel/fs2/blob/d7f1b71a8d7badb8a7ef0a8a5468807f9e384358/io/js-jvm/src/main/scala/fs2/io/net/DatagramSocketGroup.scala#L33

[armanbilge]

Aha, thanks, that would be the problem 😁