Add IPv6 support

[pznamensky]

It seems that mesh doesn't support IPv6 at the moment.

mesh/router.go

Line 102 in f76d3ef

localAddr, err := net.ResolveTCPAddr("tcp4", net.JoinHostPort(router.Host, fmt.Sprint(router.Port)))

We use IPv6 almost everywhere. And in the most cases we don't have any IPv4 addreses except 127.0.0.1.
I guess we are not alone with such setup.
Is it possible to add IPv6 support?

[rade]

Is it possible to add IPv6 support?

Sure. Shouldn't be hard. PRs welcome.

[pznamensky]

I'm not sure that it is the right way, but simple replacing tcp4 with tcp in net.ResolveTCPAddr(), net.ListenTCP() and net.DialTCP() does the trick.
I've tested mesh with prometheus alertmanager when servers have only IPv4 or only IPv6.
And this works as expected.
But when servers work both with IPv4 and IPv6 connections establish only using single address family.

[rade]

But when servers work both with IPv4 and IPv6 connections establish only using single address family.

Which one? I believe the general rule is that when there is a choice, IPv6 should be used.

[pznamensky]

I'm sorry for the delay.
But as far as I remember both were used.
Several times used IPv4. And several times used IPv6.

[mpalmer]

Since mesh peer identity isn't based on address, it shouldn't matter which address family is used to connect.