Add support for IPV6_TCLASS and IPV6_RECVTCLASS

[duskmoon314]

A simple implementation of the IPV6_TCLASS and IPV6_RECVTCLASS modeled after the existing IP_TOS and IP_RECVTOS implementations.

close #363

[Thomasdezeeuw]

Can you switch the ordering of the functions, first the getter than the setter.

[duskmoon314]

Done

Should I remove let recv_tos = i32::from(recv_tos); too?

[Thomasdezeeuw]

Should I remove let recv_tos = i32::from(recv_tos); too?

Sure 👍

[Thomasdezeeuw]

@duskmoon314 can you fix the failing CI for Windows? See https://github.com/rust-lang/socket2/actions/runs/3740167945/jobs/6348219101

[duskmoon314]

Sure. I am looking for MS documentation on this setting

[duskmoon314]

It seems that Microsoft doesn't allow modifying the traffic class of IPv6 win-socket as in Unix-like OS.

For IPv4, using IP_TOS is allowed and may correspond to history. And the doc notes that QoS API is recommended:

Do not use. Type of Service (TOS) settings should only be set using the Quality of Service API. See Differentiated Services in the Quality of Service section of the Platform SDK for more information.

https://learn.microsoft.com/en-us/windows/win32/winsock/ipproto-ip-socket-options

And for IPv6, no IPV6_TCLASS is mentioned in the doc. So this is probably why the test fails since I assume it is usable and just not be mentioned.

I am considering adding target_os = windows to the cfg not attribute. Any suggestions?

[Thomasdezeeuw]

I am considering adding target_os = windows to the cfg not attribute. Any suggestions?

Yes, that's the way to go I think. However if it's not available on Windows it need to be behind the all feature and we'll likely want to move it to sys/unix.rs. For an example see

socket2/src/sys/unix.rs

Lines 1048 to 1076 in fa67e04

	#[cfg(all(
	feature = "all",
	any(
	target_os = "android",
	target_os = "dragonfly",
	target_os = "freebsd",
	target_os = "fuchsia",
	target_os = "illumos",
	target_os = "linux",
	target_os = "netbsd",
	target_os = "openbsd"
	)
	))]
	#[cfg_attr(
	docsrs,
	doc(cfg(all(
	feature = "all",
	any(
	target_os = "android",
	target_os = "dragonfly",
	target_os = "freebsd",
	target_os = "fuchsia",
	target_os = "illumos",
	target_os = "linux",
	target_os = "netbsd",
	target_os = "openbsd"
	)
	)))
	)]

[duskmoon314]

Sure. I will modify the code ASAP.

[Thomasdezeeuw]

I'll squash the commit I've added.

[Thomasdezeeuw]

Thanks @duskmoon314!