Re: bin/58016: wg-userspace(8) requires explicit route setup

[Taylor R Campbell <riastradh%NetBSD.org@localhost>]

If I change wg-userspace(8) to do

	ifmode = IFF_BROADCAST|IFF_MULTICAST;
	if (ioctl(fd, TUNSIFMODE, &ifmode) == -1) {
		close(fd);
		fd = -1;
	}

when creating the tun(4) interface, then ifconfig(8) output looks like
this instead:

# ifconfig tun0
tun0: flags=0x8043<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
        status: active
        inet6 fd01::2/64 flags 0
        inet6 fe80::9afa:9bff:fe60:a0d2%tun0/64 flags 0 scopeid 0x4
        inet 10.1.0.2/24 broadcast 10.1.0.255 flags 0

And both inet and inet6 routes work as expected on 10.1.0.0/24
addresses:

# route -n get -inet 10.1.0.1
   route to: 10.1.0.1
destination: 10.1.0.0
       mask: 255.255.255.0
 local addr: 10.1.0.2
  interface: tun0
      flags: 0x41<UP,DONE>
 recvpipe  sendpipe  ssthresh  rtt,msec    rttvar  hopcount      mtu     expire
       0         0         0         0         0         0         0         0

# route -n get -inet6 fd01::1
   route to: fd01::1
destination: fd01::
       mask: ffff:ffff:ffff:ffff::
 local addr: fd01::2
  interface: tun0
      flags: 0x141<UP,DONE,CONNECTED>
 recvpipe  sendpipe  ssthresh  rtt,msec    rttvar  hopcount      mtu     expire
       0         0         0         0         0         0         0         0

(Still unclear on why, in the default IFF_POINTOPOINT setting of
tun(4), an explicit route is needed only for IPv4 while the system
automagically adds the necessary route for IPv6.)