On Tue, Nov 01, 2022 at 01:57:21PM +0000, Klemens Nanni wrote:
> vifscreate() is used to create all virtual interfaces up-front and is
> always called at the beginning of netstart, whether an explicit list of
> interfaces is passed or none, i.e. all are to be configured.
>
> Yet, to check the given interface exists, ifstart() uses ifcreate()
> which obviously tries to create interfaces.
>
> When ifstart() is run for every hostname.if(5) file, every virtual
> interface is guaranteed to exist thanks to vifscreate().
>
> Nonexistent physical interfaces with an existent config, e.g. urndis(4)
> and cdce(4), will be skipped by ifstart() due to the failed ifcreate()
> call, but not without ifcreate() trying the impossible:
>
> $ ifconfig urndis0
> urndis0: no such interface
> # sh /etc/netstart -n urndis0
> { ifconfig urndis0 || ifconfig urndis0 create; }
> ifconfig urndis0 inet6 autoconf
> ifconfig urndis0 inet autoconf
>
> This dry-run output does NOT match what netstart would really do:
>
> # sh -x /etc/netstart urndis0 2>&1 | tail -n4
> + vifscreate urndis0
> + ifstart urndis0
> + defaultroute
> + return
>
> Here, ifstart() runs but bails out on the failing ifcreate() call and
> thus skips configuring urndis0 entirely.
>
>
> So clarify the comment and replace the ifcreate() call with a simpler,
> more obvious `ifconfig' check, which is exactly what ifcreate() boils
> down to for existing interfaces:
>
> # sh ./netstart -n urndis0 ; echo $?
> 0
>
> Actual steps taken remain the same, i.e. none, as the new dry-run output
> truthfully tells:
>
> # sh -x ./netstart urndis0 2>&1 | tail -n4
> + vifscreate urndis0
> + ifstart urndis0
> + defaultroute
> + return
>
>
> Virtual interfaces are now also created only once:
>
> # sh /etc/netstart -n veb0
> { ifconfig veb0 || ifconfig veb0 create; }
> { ifconfig veb0 || ifconfig veb0 create; }
> ifconfig veb0 description 'vmd(4) uplink'
> ifconfig veb0 up
> # sh ./netstart -n veb0
> { ifconfig veb0 || ifconfig veb0 create; }
> ifconfig veb0 description 'vmd(4) uplink'
> ifconfig veb0 up
>
> Feedback? OK?
Ping.
netstart and the installer's copy still remain in sync as best as
possible: the installer keeps creating interfaces as it doesn't have
any of this create-virtual-interfaces-up-front logic at all.
Index: netstart
===================================================================
RCS file: /cvs/src/etc/netstart,v
retrieving revision 1.229
diff -u -p -r1.229 netstart
--- netstart 5 Nov 2022 12:06:05 -0000 1.229
+++ netstart 9 Nov 2022 13:14:46 -0000
@@ -152,8 +152,8 @@ ifstart() {
chown -LR root:wheel $_hn
fi
- # Check for ifconfig'able interface, except if -n option is specified.
- ifcreate $_if || return
+ # Skip missing physical interface, virtual ones were created up front.
+ ifconfig $_if >/dev/null 2>&1 || return
# Parse the hostname.if(5) file and fill _cmds array with interface
# configuration commands.
