Prevent the nd6_addr_add() work queue task from adding multiple addresses

for the same prefix. Tested by giovanni@, steven@, Dennis den Brok.
ok dlg miod claudio

1 files changed, 37 insertions, 1 deletions

diff --git a/sys/netinet6/nd6_rtr.c b/sys/netinet6/nd6_rtr.c
index e96d15a5a31..f783f0c4489 100644
--- a/sys/netinet6/nd6_rtr.c
+++ b/sys/netinet6/nd6_rtr.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: nd6_rtr.c,v 1.54 2010/09/24 14:10:52 jsing Exp $	*/
+/*	$OpenBSD: nd6_rtr.c,v 1.55 2011/02/24 01:25:17 stsp Exp $	*/
 /*	$KAME: nd6_rtr.c,v 1.97 2001/02/07 11:09:13 itojun Exp $	*/
 
 /*
@@ -1297,6 +1297,42 @@ nd6_addr_add(void *prptr, void *arg2)
 {
 	struct nd_prefix *pr = (struct nd_prefix *)prptr;
 	struct in6_ifaddr *ia6 = NULL;
+	struct ifaddr *ifa;
+	int ifa_plen;
+
+	/* Because prelist_update() runs in interrupt context it may run
+	 * again before this work queue task is run, causing multiple work
+	 * queue tasks to be scheduled all of which add addresses for the
+	 * same prefix. So check again if a non-deprecated address has already
+	 * been autoconfigured for this prefix. */
+	TAILQ_FOREACH(ifa, &pr->ndpr_ifp->if_addrlist, ifa_list) {
+		if (ifa->ifa_addr->sa_family != AF_INET6)
+			continue;
+
+		ia6 = (struct in6_ifaddr *)ifa;
+
+		/*
+		 * Spec is not clear here, but I believe we should concentrate
+		 * on unicast (i.e. not anycast) addresses.
+		 * XXX: other ia6_flags? detached or duplicated?
+		 */
+		if ((ia6->ia6_flags & IN6_IFF_ANYCAST) != 0)
+			continue;
+
+		if ((ia6->ia6_flags & IN6_IFF_AUTOCONF) == 0)
+			continue;
+
+		if ((ia6->ia6_flags & IN6_IFF_DEPRECATED) != 0)
+			continue;
+
+		ifa_plen = in6_mask2len(&ia6->ia_prefixmask.sin6_addr, NULL);
+		if (ifa_plen == pr->ndpr_plen &&
+		    in6_are_prefix_equal(&ia6->ia_addr.sin6_addr,
+		    &pr->ndpr_prefix.sin6_addr, ifa_plen)) {
+			pr->ndpr_refcnt--;
+			return;
+		}
+	}
 
 	if ((ia6 = in6_ifadd(pr)) != NULL) {
 		ia6->ia6_ndpr = pr;