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Date:      Thu, 7 Mar 2019 23:03:39 +0000 (UTC)
From:      "Bjoern A. Zeeb" <bz@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r344904 - head/sys/netinet6
Message-ID:  <201903072303.x27N3dqr033758@repo.freebsd.org>
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Author: bz
Date: Thu Mar  7 23:03:39 2019
New Revision: 344904
URL: https://svnweb.freebsd.org/changeset/base/344904

Log:
  Update for IETF draft-ietf-6man-ipv6only-flag.
  
  When we roam between networks and our link-state goes down, automatically remove
  the IPv6-Only flag from the interface.  Otherwise we might switch from an
  IPv6-only to and IPv4-only network and the flag would stay and we would prevent
  IPv4 from working.
  
  While the actual function call to clear the flag is under EXPERIMENTAL,
  the eventhandler is not as we might want to re-use it for other
  functionality on link-down event (such was re-calculate default routers
  for example if there is more than one).
  
  Reviewed by:	hrs
  Differential Revision:	https://reviews.freebsd.org/D19487

Modified:
  head/sys/netinet6/nd6.c
  head/sys/netinet6/nd6.h
  head/sys/netinet6/nd6_rtr.c

Modified: head/sys/netinet6/nd6.c
==============================================================================
--- head/sys/netinet6/nd6.c	Thu Mar  7 22:56:39 2019	(r344903)
+++ head/sys/netinet6/nd6.c	Thu Mar  7 23:03:39 2019	(r344904)
@@ -113,7 +113,7 @@ VNET_DEFINE(int, nd6_debug) = 1;
 VNET_DEFINE(int, nd6_debug) = 0;
 #endif
 
-static eventhandler_tag lle_event_eh, iflladdr_event_eh;
+static eventhandler_tag lle_event_eh, iflladdr_event_eh, ifnet_link_event_eh;
 
 VNET_DEFINE(struct nd_drhead, nd_defrouter);
 VNET_DEFINE(struct nd_prhead, nd_prefix);
@@ -233,6 +233,8 @@ nd6_init(void)
 		    NULL, EVENTHANDLER_PRI_ANY);
 		iflladdr_event_eh = EVENTHANDLER_REGISTER(iflladdr_event,
 		    nd6_iflladdr, NULL, EVENTHANDLER_PRI_ANY);
+		ifnet_link_event_eh = EVENTHANDLER_REGISTER(ifnet_link_event,
+		    nd6_ifnet_link_event, NULL, EVENTHANDLER_PRI_ANY);
 	}
 }
 
@@ -244,6 +246,7 @@ nd6_destroy()
 	callout_drain(&V_nd6_slowtimo_ch);
 	callout_drain(&V_nd6_timer_ch);
 	if (IS_DEFAULT_VNET(curvnet)) {
+		EVENTHANDLER_DEREGISTER(ifnet_link_event, ifnet_link_event_eh);
 		EVENTHANDLER_DEREGISTER(lle_event, lle_event_eh);
 		EVENTHANDLER_DEREGISTER(iflladdr_event, iflladdr_event_eh);
 	}

Modified: head/sys/netinet6/nd6.h
==============================================================================
--- head/sys/netinet6/nd6.h	Thu Mar  7 22:56:39 2019	(r344903)
+++ head/sys/netinet6/nd6.h	Thu Mar  7 23:03:39 2019	(r344904)
@@ -476,6 +476,7 @@ void nd6_dad_stop(struct ifaddr *);
 /* nd6_rtr.c */
 void nd6_rs_input(struct mbuf *, int, int);
 void nd6_ra_input(struct mbuf *, int, int);
+void nd6_ifnet_link_event(void *, struct ifnet *, int);
 void defrouter_reset(void);
 void defrouter_select_fib(int fibnum);
 void defrouter_select(void);

Modified: head/sys/netinet6/nd6_rtr.c
==============================================================================
--- head/sys/netinet6/nd6_rtr.c	Thu Mar  7 22:56:39 2019	(r344903)
+++ head/sys/netinet6/nd6_rtr.c	Thu Mar  7 23:03:39 2019	(r344904)
@@ -285,7 +285,32 @@ defrtr_ipv6_only_ifp(struct ifnet *ifp)
 	/* Send notification of flag change. */
 #endif
 }
+
+static void
+defrtr_ipv6_only_ipf_down(struct ifnet *ifp)
+{
+
+	IF_AFDATA_WLOCK(ifp);
+	ND_IFINFO(ifp)->flags &= ~ND6_IFF_IPV6_ONLY;
+	IF_AFDATA_WUNLOCK(ifp);
+}
 #endif	/* EXPERIMENTAL */
+
+void
+nd6_ifnet_link_event(void *arg __unused, struct ifnet *ifp, int linkstate)
+{
+
+	/*
+	 * XXX-BZ we might want to trigger re-evaluation of our default router
+	 * availability. E.g., on link down the default router might be
+	 * unreachable but a different interface might still have connectivity.
+	 */
+
+#ifdef EXPERIMENTAL
+	if (linkstate == LINK_STATE_DOWN)
+		defrtr_ipv6_only_ipf_down(ifp);
+#endif
+}
 
 /*
  * Receive Router Advertisement Message.

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