internal/wgfreebsd: support for new FreeBSD kernel interface

[mdlayher]

@mattmacy is working on a FreeBSD kernel implementation of WireGuard at https://github.com/mattmacy/wg-fbsd and the repo is going to be moved to https://git.zx2c4.com/wireguard-freebsd/about/ soon. We should support this interface.

[afeiszli]

@mdlayher Is there still no support for FreeBSD with wgctrl-go? Just ran into an issue trying to retrieve the interface while attempting to integrate on FreeBSD.

[mdlayher]

No work has been done on FreeBSD kernel interfaces at this point. Userspace should work fine.

[afeiszli]

@mdlayher is there any way to tell wgctrl to use userspace when calling wgctrl.New? If not, is there a way to trick it into thinking it should be using userspace? I think that would be sufficient for our purposes.

[mdlayher]

You shouldn't need to care about the underlying implementation. If wireguard-go or similar is running and exposes a control socket, it should be picked up automatically. We look for sockets using https://github.com/WireGuard/wgctrl-go/blob/master/internal/wguser/conn_unix.go#L19-L26. If they exist at a different path, that path would need to be added too.

[afeiszli]

I'm definitely missing something. Not sure which path sockets get added to, but wireguard was installed on freebsd using:

pkg install wireguard

There is an active, functioning interface, but no /var/run/wireguard

root@freebsd-machine:~ # wg
interface: wg0
  public key: XXXXXXXXXXXXX
  private key: (hidden)
  listening port: 51821

peer: YYYYYYYYYYYYYY
  endpoint: 1.2.3.4:51821
  allowed ips: 10.101.0.1/32
  latest handshake: 29 seconds ago
  transfer: 5.09 KiB received, 20.28 KiB sent
  persistent keepalive: every 20 seconds

root@freebsd-machine:~ # sockstat -l
?        ?          ?     ?  udp6   *:51821               *:*
?        ?          ?     ?  udp4   *:51821               *:*

and wgctrl.New() returns no devices.

[mdlayher]

Based on https://www.freshports.org/net/wireguard, you're probably using the kernel module implementation, which is not supported yet.

[stv0g]

I've started with implementation. Much of the code is similar to the OpenBSD kernel interface with the exception of the encoding which uses FreeBSD's nv(9) library.

I am currently using CGo to link against libnv which might not be optimal but got me started the fastest.

@mdlayher Is it acceptable to use CGo for wgctrl-go? Or do we need to implement a pure Go implementation of libnv?

There is already an incompatible Golang implementation for OpenZFS nvlist here: https://pkg.go.dev/git.dolansoft.org/lorenz/go-zfs/nvlist

[mdlayher]

Nice work! I have no objections to starting with cgo. Presumably that library is widely used on freebsd anyway?

[stv0g]

I have no objections to starting with cgo.

Thanks. I will try to finish the the ConfigureDevice() today and add some tests.

Presumably that library is widely used on freebsd anyway?

Yes, it ships with the standard installation.

[stv0g]

@mdlayher I just pushed a version to #126 which implements the full client interface.

I've tested it with my own code on an ARM64 FreeBSD VM running on my M1 Mac with Parallels.