Re: Ctrl-c abort of dhclient during rc.d start aborts all network configuration

From: Brooks Davis (brooks_at_one-eyed-alien.net)
Date: 08/31/05

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    Date: Wed, 31 Aug 2005 14:04:57 -0700
To: Robert Watson <rwatson@FreeBSD.org>

    On Wed, Aug 31, 2005 at 09:42:58PM +0100, Robert Watson wrote:
    >
    > On Wed, 31 Aug 2005, Brooks Davis wrote:
    >
    > >The wait should be 10 seconds plus some startup time.
    >
    > It seemed a bit longer, but maybe I was counting fast. I'll time it next
    > time and see if there's more going on there.

    It seems longer, but here's what I got with a quick trial:

    # time dhclient em0
    em0: no link .............. giving up
           11.05 real 0.00 user 0.01 sys

    > >>(1) It would be good to configure lo0 first.
    > >
    > >Interfaces are configured in order of index by default. If lo0 were
    > >attached sooner, it would be configured sooner. I'm somewhat tempted to
    > >change it from it's current (apparently bogus) position in the startup
    > >process at SI_SUB_PROTO_IFATTACHDOMAIN to SI_SUB_INIT_IF/SI_ORDER_ANY
    > >and push the l2com attachments from SI_ORDER_ANY to SI_ORDER_MIDDLE.
    > >Strictly speaking I think lo(4) should be SI_SUB_PSEUDO, but moving it
    > >up so it attached first makes some sense given how critical it is.
    > >
    > >Alternativly, one could add code to sort the result of "ifconfig -l" to
    > >configure lo0 first.
    >
    > I wonder if we could sed out lo0 from the automatic list and just
    > configure it first by fiat? While if_loop is in theory optional, it turns
    > out not to be very practical using our default boot scripts (since many
    > tools assume you can bind 0.0.0.0).

    That's probably a good idea though we don't have sed yet at this point
    in the process. I believe in practice, if you have either INET or INET6
    compiled in and don't load lo you'll panic in the routing code.

    > >>(2) If a dhclient is ctrl-c'd, it would be nice if the rest of the network
    > >> configuration continued.
    > >
    > >I don't see any code in the startup scripts that would cause them to
    > >exit on failure so the issue is probalby that the signal is being
    > >delivered to the /etc/rc.d/netif instance. I don't really know what the
    > >solution to that is.
    >
    > Me neither. All I know is that I don't remember seeing this before.

    I think I'll add a "trap : 3" like fsck has.

    > >>The printing of '.'s in dhclient is also a bit excessive.
    > >
    > >Hanging with no output seems even less unhelpful. :( Longer term I want
    > >to get rid of syncronous calls to dhclient in the startup process, but I
    > >haven't had time to work on it and IMO, it's a bit late in the game for
    > >6.0.
    >
    > I thought a bit about this, but concluded that we probably still have
    > components that assume a one IP (no more, no less) world, and slide by now
    > due to luck. A gradual conversion towards the assumptions of changing IPs
    > has been happening over time (vis natd -dynamic), but perhaps we need to
    > accelerate it some by forcing the issue in 7.x after 6.0 gets out the
    > door?

    I definitely think this is something we need to work on for 7.x.
    Fortunately, I think Apple has probably shaken out the bugs in the big
    applications like bind and apache since they have a nice, dynamic
    interface configuration process.

    -- Brooks
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