support for listening on any interface

[icorderi]

Some deployments require us to be able able continue listening even when the interfaces available change underneath us.

To do so, we must join a multicast group on any interface.

[icorderi]

@GGist

As of right now,

• the code works on Linux, should work on the bsd's
• I have verified it fails on macOS and,
• I'm uncertain about Windows.

I'm still not sure about keeping:

#[cfg(not(linux))]
fn listen_any_on_port(port: u16) -> SSDPResult<SSDPReceiver<Self::Message>> {
    Self::listen_on_port(port)
}

Having it fallback to listening on interfaces that are present at that moment is a bit misleading.

---

It would be nice to figure out why macOS is rejecting interface 0. If you can verify it works on Windows we can change the code to be flagged as #[cfg(not(macos))] until we figure out how to make it work on it.

---

The first couple commits are on PR #36

[GGist]

@icorderi I agree that it is a bit confusing, though I also agree that this functionality is valuable.

I can confirm on Windows that joining with interface 0 will not work as intended as Windows will just join on the default interface if passed 0. The last time interface 0 came up in a previous PR I could not find out any way to achieve Linux like behavior for interface 0 on Windows.

The code looks good. Go ahead and remove this bit:

// Is is possible that binding on interface 0 works on the ipv6 stack in windows
// I have not tested it

And I'll merge it in.

Thanks!

[GGist]

On second thought, I think we should go ahead and just remove listen_any_on_port for non Linux platforms.

[icorderi]

@GGist, removed the non-linux platform bits

[GGist]

Thanks!