Do not return EEXIST if the same address is added twice.

Reported by sebastisa@.

ok sebasitia@, stsp@, florian@, vgross@

1 files changed, 12 insertions, 5 deletions

diff --git a/sys/netinet6/in6.c b/sys/netinet6/in6.c
index 1072a8a780d..a2c6b67b223 100644
--- a/sys/netinet6/in6.c
+++ b/sys/netinet6/in6.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: in6.c,v 1.181 2015/12/03 13:13:42 tedu Exp $	*/
+/*	$OpenBSD: in6.c,v 1.182 2015/12/22 10:01:01 mpi Exp $	*/
 /*	$KAME: in6.c,v 1.372 2004/06/14 08:14:21 itojun Exp $	*/
 
 /*
@@ -444,7 +444,7 @@ in6_control(struct socket *so, u_long cmd, caddr_t data, struct ifnet *ifp)
 
 	case SIOCAIFADDR_IN6:
 	{
-		int plen, error = 0;
+		int plen, error = 0, newifaddr = 0;
 
 		/* reject read-only flags */
 		if ((ifra->ifra_flags & IN6_IFF_DUPLICATED) != 0 ||
@@ -454,12 +454,15 @@ in6_control(struct socket *so, u_long cmd, caddr_t data, struct ifnet *ifp)
 			return (EINVAL);
 		}
 
+		if (ia6 == NULL)
+			newifaddr = 1;
+
 		/*
 		 * Make the address tentative before joining multicast
 		 * addresses, so that corresponding MLD responses would
 		 * not have a tentative source address.
 		 */
-		if ((ia6 == NULL) && in6if_do_dad(ifp))
+		if (newifaddr && in6if_do_dad(ifp))
 			ifra->ifra_flags |= IN6_IFF_TENTATIVE;
 
 		/*
@@ -477,8 +480,9 @@ in6_control(struct socket *so, u_long cmd, caddr_t data, struct ifnet *ifp)
 		splx(s);
 		if (error != 0)
 			return (error);
-		if ((ia6 = in6ifa_ifpwithaddr(ifp, &ifra->ifra_addr.sin6_addr))
-		    == NULL) {
+
+		ia6 = in6ifa_ifpwithaddr(ifp, &ifra->ifra_addr.sin6_addr);
+		if (ia6 == NULL) {
 			/*
 			 * this can happen when the user specify the 0 valid
 			 * lifetime.
@@ -486,6 +490,9 @@ in6_control(struct socket *so, u_long cmd, caddr_t data, struct ifnet *ifp)
 			break;
 		}
 
+		if (!newifaddr)
+			break;
+
 		/* Perform DAD, if needed. */
 		if (ia6->ia6_flags & IN6_IFF_TENTATIVE)
 			nd6_dad_start(&ia6->ia_ifa);