Re: r239356: does it mean, that synchronous dhcp and dhcplcinet with disabled devd gone?

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_at_ 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)
> _at__at_ -208,6 +208,7 _at__at_
>  	int			 errors;
>  	int			 dead;
>  	u_int16_t		 index;
> +	int			 linkstat;
>  };
>  
>  struct timeout {
> Index: dhclient.c
> ===================================================================
> --- dhclient.c	(revision 239498)
> +++ dhclient.c	(working copy)
> _at__at_ -218,6 +218,7 _at__at_
>  	struct sockaddr *sa;
>  	struct iaddr a;
>  	ssize_t n;
> +	int linkstat;
>  
>  	n = read(routefd, &msg, sizeof(msg));
>  	rtm = (struct rt_msghdr *)msg;
> _at__at_ -278,10 +279,14 _at__at_
>  			    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:
> _at__at_ -321,8 +326,6 _at__at_
>  
>  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();
> _at__at_ -437,6 +440,7 _at__at_
>  		}
>  		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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