Date: Wed, 22 Aug 2012 03:16:30 +0400 From: Slawa Olhovchenkov <slw@zxy.spb.ru> To: John Baldwin <jhb@freebsd.org> Cc: Garrett Cooper <yanegomi@gmail.com>, freebsd-current@freebsd.org, lev@freebsd.org, current@freebsd.org, Peter Jeremy <peterjeremy@acm.org> Subject: Re: r239356: does it mean, that synchronous dhcp and dhcplcinet with disabled devd gone? Message-ID: <20120821231630.GF88729@zxy.spb.ru> In-Reply-To: <201208211725.23381.jhb@freebsd.org> References: <20120821095527.GA33206@hell.ukr.net> <1959717636.20120821155308@serebryakov.spb.ru> <201208210934.31484.jhb@freebsd.org> <201208211725.23381.jhb@freebsd.org>
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On Tue, Aug 21, 2012 at 05:25:23PM -0400, John Baldwin wrote:
> On Tuesday, August 21, 2012 9:34:31 am John Baldwin wrote:
> > On Tuesday, August 21, 2012 7:53:08 am Lev Serebryakov wrote:
> > > Hello, Garrett.
> > > You wrote 21 августа 2012 г., 15:40:35:
> > >
> > > GC>> Try reverting r239356 -- if that works, then please let jhb@ know.
> > > LS> I'm confused by this commit, because it seems (from comment alone),
> > > LS> that dhclient will not work without devd anymore (with "synchronous
> > > LS> dhcp" option in rc.conf).
> > > LS> Am I right?
> > > And if I'm right about understanding what this change does, it is
> > > POLA violation for sure. Both consequences: unable to use dhcclient
> > > without devd (user will need to restart it by hands after each cable
> > > unplugging event) and removing IP address from interface on cable
> > > unplugging or other interface down event but before lease is expired.
> > >
> > > If I'm right in understanding this commit, I vote to back it out and
> > > find better solution, may be, two new options: one to remove IP and
> > > one to exit on interface down. And default behavior should be OLD
> > > ONE about IP address in any case and OLD ONE about exit in case when
> > > dhclient isn't started by devd, but by rc scripts directly.
> >
> > Humm. devd is the more common case, and we explicitly don't use devd to start
> > dhclient on boot even when devd is enabled (so out of the box dhcp would first
> > be started by rc, but would be restarted by devd).
> >
> > Another option is to rework dhclient to work like it does on OpenBSD where it
> > renews its lease if the link bounces, but to not exit when the link goes down.
> > That case would fix the currently broken case that you unplug your cable, take
> > your laptop over to another network (e.g. take it home if suspend/resume
> > works), then plug it back in and are still stuck with your old IP.
>
> Ok, this is what I came up with, somewhat loosely based on OpenBSD's dhclient.
> I tested that it survives the following:
>
> - Unplugging/replugging does not kill an existing ssh session
> - Using ifconfig down/up does not kill an existing ssh session
> - Plugging into a different network does cause dhclient to negotiate
> a new lease on the new network
Assign address on interface manualy cause exiting dhcpclient?
> I've removed the bits to clear the old configuration if dhclient exits due to
> 'ifconfig down', and dhclient no longer exits on link down, but instead tracks
> the link state and enters the 'reboot' state when the link goes up.
>
> Index: dhcpd.h
> ===================================================================
> --- dhcpd.h (revision 239498)
> +++ dhcpd.h (working copy)
> @@ -208,6 +208,7 @@
> int errors;
> int dead;
> u_int16_t index;
> + int linkstat;
> };
>
> struct timeout {
> Index: dhclient.c
> ===================================================================
> --- dhclient.c (revision 239498)
> +++ dhclient.c (working copy)
> @@ -218,6 +218,7 @@
> struct sockaddr *sa;
> struct iaddr a;
> ssize_t n;
> + int linkstat;
>
> n = read(routefd, &msg, sizeof(msg));
> rtm = (struct rt_msghdr *)msg;
> @@ -278,10 +279,14 @@
> ifi->name);
> goto die;
> }
> - if (!interface_link_status(ifi->name)) {
> - warning("Interface %s is down, dhclient exiting",
> - ifi->name);
> - goto die;
> + linkstat = interface_link_status(ifi->name);
> + if (linkstat != ifi->linkstat) {
> + debug("%s link state %s -> %s", ifi->name,
> + ifi->linkstat ? "up" : "down",
> + linkstat ? "up" : "down");
> + ifi->linkstat = linkstat;
> + if (linkstat)
> + state_reboot(ifi);
> }
> break;
> case RTM_IFANNOUNCE:
> @@ -321,8 +326,6 @@
>
> die:
> script_init("FAIL", NULL);
> - if (ifi->client->active)
> - script_write_params("old_", ifi->client->active);
> if (ifi->client->alias)
> script_write_params("alias_", ifi->client->alias);
> script_go();
> @@ -437,6 +440,7 @@
> }
> fprintf(stderr, " got link\n");
> }
> + ifi->linkstat = 1;
>
> if ((nullfd = open(_PATH_DEVNULL, O_RDWR, 0)) == -1)
> error("cannot open %s: %m", _PATH_DEVNULL);
>
> --
> John Baldwin
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