dhclient appears to misinterpret the exit status of dhclient-script

[Ryan Moeller]

Nice catch! Apparently this was fixed in OpenBSD 11 years ago, before they nuked the whole script thing.
https://github.com/openbsd/src/commit/b215a882fd7e98ff38505d62bfc539bee124e0ee

> On Feb 7, 2019, at 6:45 PM, Nash Kaminski <nashkaminski at gmail.com> wrote:
> 
> Hello,
> 
> I have been attempting to debug a peculiar issue with dhclient on a
> vanilla FreeBSD 11.2 system where it appears that even if
> dhclient-script returns nonzero when invoked in response to a protocol
> timeout, dhclient continues as if the address was bound successfully,
> as opposed to the protocol being restarted after the defined retry
> interval.
> 
> After some investigation, it appears that the root cause of this
> behavior is a result of the lower byte of the exit status being
> returned, instead of the upper byte containing the return code, on
> line 2319 of sbin/dhclient/dhclient.c (Ref:
> https://github.com/freebsd/freebsd/blob/releng/11.2/sbin/dhclient/dhclient.c#L2319).
> 
> Making the following change makes dhclient behave as expected. Am I
> missing something or is there indeed a significant bug here?
> 
> Index: sbin/dhclient/dhclient.c
> ===================================================================
> --- sbin/dhclient/dhclient.c    (revision 342377)
> +++ sbin/dhclient/dhclient.c    (working copy)
> @@ -2316,7 +2316,7 @@
>        if (ip)
>                script_flush_env(ip->client);
> 
> -       return (wstatus & 0xff);
> +       return WEXITSTATUS(wstatus);
> 
> }
> 
> 
> - Nash
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