Re: [PATCH] FreeBSD default tun name patch

[Kyle Evans <kevans@freebsd.org>]

On Sun, Mar 7, 2021 at 9:45 AM kayrus <kay.diam@gmail.com> wrote:
>
> This change allows to omit the tun interface name setting in FreeBSD. When name
> is not set, kernel automatically picks up the tun name and index.
> ---
>  tun/tun_freebsd.go | 34 ++++++++++++++++++----------------
>  1 file changed, 18 insertions(+), 16 deletions(-)
>

Hi,

I'm a little confused by what's going on here -- folks are wanting to
use the assigned name from the tuntap cloner, or is it just a desire
to not require that a new name be specified? The latter seems
incompatible with how the Linux counterpart works, but perhaps Linux
doesn't assign a name/unit when opening /dev/net/tun like we do.

Thanks,

Kyle Evans


> diff --git a/tun/tun_freebsd.go b/tun/tun_freebsd.go
> index 12b44da..1883aad 100644
> --- a/tun/tun_freebsd.go
> +++ b/tun/tun_freebsd.go
> @@ -346,22 +346,24 @@ func CreateTUN(name string, mtu int) (Device, error) {
>                 return nil, fmt.Errorf("Unable to set nd6 flags for %s: %w", assignedName, errno)
>         }
>
> -       // Rename the interface
> -       var newnp [unix.IFNAMSIZ]byte
> -       copy(newnp[:], name)
> -       var ifr ifreq_ptr
> -       copy(ifr.Name[:], assignedName)
> -       ifr.Data = uintptr(unsafe.Pointer(&newnp[0]))
> -       _, _, errno = unix.Syscall(
> -               unix.SYS_IOCTL,
> -               uintptr(confd),
> -               uintptr(unix.SIOCSIFNAME),
> -               uintptr(unsafe.Pointer(&ifr)),
> -       )
> -       if errno != 0 {
> -               tunFile.Close()
> -               tunDestroy(assignedName)
> -               return nil, fmt.Errorf("Failed to rename %s to %s: %w", assignedName, name, errno)
> +       if name != "" {
> +               // Rename the interface
> +               var newnp [unix.IFNAMSIZ]byte
> +               copy(newnp[:], name)
> +               var ifr ifreq_ptr
> +               copy(ifr.Name[:], assignedName)
> +               ifr.Data = uintptr(unsafe.Pointer(&newnp[0]))
> +               _, _, errno = unix.Syscall(
> +                       unix.SYS_IOCTL,
> +                       uintptr(confd),
> +                       uintptr(unix.SIOCSIFNAME),
> +                       uintptr(unsafe.Pointer(&ifr)),
> +               )
> +               if errno != 0 {
> +                       tunFile.Close()
> +                       tunDestroy(assignedName)
> +                       return nil, fmt.Errorf("Failed to rename %s to %s: %w", assignedName, name, errno)
> +               }
>         }
>
>         return CreateTUNFromFile(tunFile, mtu)
> --
> 2.25.1
>