Re: dhclient cause up/down cycle after 239356 ?

On Wednesday, August 22, 2012 1:28:22 pm Vitalij Satanivskij wrote:
> ok next round :) 
> 
> dhclient updated to Revision 239564 
> 
> with fxp : 
> 
> Aug 22 20:06:48 home kernel: fxp0: link state changed to DOWN
> Aug 22 20:06:48 home dhclient: New Subnet Mask (fxp0): 255.255.255.0
> Aug 22 20:06:48 home dhclient: New Broadcast Address (fxp0): xx.xx.xx.255
> Aug 22 20:06:48 home dhclient: New Routers (fxp0): xx.xx.xx.1
> Aug 22 20:06:50 home kernel: fxp0: link state changed to UP
> Aug 22 20:06:53 home dhclient: New IP Address (fxp0): xx.xx.xx.xx
> Aug 22 20:06:53 home kernel: fxp0: link state changed to DOWN
> Aug 22 20:06:53 home dhclient: New Subnet Mask (fxp0): 255.255.255.0
> Aug 22 20:06:53 home dhclient: New Broadcast Address (fxp0): xx.xx.xx.255
> Aug 22 20:06:53 home dhclient: New Routers (fxp0): xx.xx.xx.xx
> Aug 22 20:06:55 home kernel: fxp0: link state changed to UP
> Aug 22 20:07:01 home dhclient: New IP Address (fxp0): xx.xx.xx.xx
> Aug 22 20:07:01 home kernel: fxp0: link state changed to DOWN
> Aug 22 20:07:01 home dhclient: New Subnet Mask (fxp0): 255.255.255.0
> Aug 22 20:07:01 home dhclient: New Broadcast Address (fxp0): xx.xx.xx.255
> Aug 22 20:07:01 home dhclient: New Routers (fxp0): xx.xx.xx.xx
> Aug 22 20:07:03 home kernel: fxp0: link state changed to UP
> Aug 22 20:07:07 home dhclient: New IP Address (fxp0): xx.xx.xx.xx
> Aug 22 20:07:07 home kernel: fxp0: link state changed to DOWN
> Aug 22 20:07:07 home dhclient: New Subnet Mask (fxp0): 255.255.255.0
> Aug 22 20:07:07 home dhclient: New Broadcast Address (fxp0): xx.xx.xx.255
> Aug 22 20:07:07 home dhclient: New Routers (fxp0): xx.xx.xx.xx
> Aug 22 20:07:09 home kernel: fxp0: link state changed to UP
> Aug 22 20:07:13 home dhclient: New IP Address (fxp0): xx.xx.xx.xx
> Aug 22 20:07:13 home kernel: fxp0: link state changed to DOWN
> Aug 22 20:07:13 home dhclient: New Subnet Mask (fxp0): 255.255.255.0
> Aug 22 20:07:13 home dhclient: New Broadcast Address (fxp0): xx.xx.xx.255
> Aug 22 20:07:13 home dhclient: New Routers (fxp0): xx.xx.xx.xx
> Aug 22 20:07:15 home kernel: fxp0: link state changed to UP

Hmm.  Perhaps we could use a debouncer to ignore "short" link flaps?  Kind of
gross (and OpenBSD doesn't do this).  For now this change basically ignores
link up events if they occur with 5 seconds of the link down event.  The 5 is
hardcoded which is kind of yuck.

Index: dhcpd.h
===================================================================
--- dhcpd.h	(revision 239564)
+++ dhcpd.h	(working copy)
_at__at_ -209,6 +209,7 _at__at_
 	int			 dead;
 	u_int16_t		 index;
 	int			 linkstat;
+	time_t			 linktime;
 };
 
 struct timeout {
Index: dhclient.c
===================================================================
--- dhclient.c	(revision 239564)
+++ dhclient.c	(working copy)
_at__at_ -285,8 +285,14 _at__at_
 			    ifi->linkstat ? "up" : "down",
 			    linkstat ? "up" : "down");
 			ifi->linkstat = linkstat;
-			if (linkstat)
+
+			/*
+			 * XXX: Hardcoded 5 second grace window on
+			 * link flaps.
+			 */
+			if (linkstat && (cur_time - ifi->linktime) >= 5)
 				state_reboot(ifi);
+			ifi->linktime = cur_time;
 		}
 		break;
 	case RTM_IFANNOUNCE:
_at__at_ -441,6 +447,7 _at__at_
 		fprintf(stderr, " got link\n");
 	}
 	ifi->linkstat = 1;
+	ifi->linktime = cur_time;
 
 	if ((nullfd = open(_PATH_DEVNULL, O_RDWR, 0)) == -1)
 		error("cannot open %s: %m", _PATH_DEVNULL);

-- 
John Baldwin