[src/trunk]: src/sys/netinet Only check target address collision if the sende...

[roy <roy%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/3be4e7961df8
branches:  trunk
changeset: 351994:3be4e7961df8
user:      roy <roy%NetBSD.org@localhost>
date:      Thu Mar 09 08:41:56 2017 +0000

description:
Only check target address collision if the sender address is the null
address (ie a DAD probe) or our matching address is either TENTATIVE
or DUPLICATED.

diffstat:

 sys/netinet/if_arp.c |  16 ++++++++++++----
 1 files changed, 12 insertions(+), 4 deletions(-)

diffs (40 lines):

diff -r 1075aed63081 -r 3be4e7961df8 sys/netinet/if_arp.c
--- a/sys/netinet/if_arp.c      Thu Mar 09 08:27:18 2017 +0000
+++ b/sys/netinet/if_arp.c      Thu Mar 09 08:41:56 2017 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: if_arp.c,v 1.244 2017/02/24 13:42:18 roy Exp $ */
+/*     $NetBSD: if_arp.c,v 1.245 2017/03/09 08:41:56 roy Exp $ */
 
 /*-
  * Copyright (c) 1998, 2000, 2008 The NetBSD Foundation, Inc.
@@ -68,7 +68,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: if_arp.c,v 1.244 2017/02/24 13:42:18 roy Exp $");
+__KERNEL_RCSID(0, "$NetBSD: if_arp.c,v 1.245 2017/03/09 08:41:56 roy Exp $");
 
 #ifdef _KERNEL_OPT
 #include "opt_ddb.h"
@@ -1163,11 +1163,19 @@
                goto out;
        }
 
-       /* DAD check, RFC 5227 */
+       /*
+        * DAD check, RFC 5227.
+        * Collision on sender address is always a duplicate.
+        * Collision on target address is only a duplicate IF
+        * the sender address is the null host (ie a DAD probe) AND
+        * our address is in the TENTATIVE state.
+        * DUPLICATED state is also checked so that processing stops here
+        * and an error can be logged.
+        */
        if (do_dad &&
            (in_hosteq(isaddr, myaddr) ||
            (in_nullhost(isaddr) && in_hosteq(itaddr, myaddr)
-           && ISSET(m->m_flags, M_BCAST)))) /* Allow Unicast Poll, RFC 1122 */
+           && ia->ia4_flags & (IN_IFF_TENTATIVE | IN_IFF_DUPLICATED))))
        {
                arp_dad_duplicated((struct ifaddr *)ia,
                    lla_snprintf(llabuf, ar_sha(ah), ah->ar_hln));