--- src/sys/netinet6/in6.c	2008/04/20 13:44:26	1.29
+++ src/sys/netinet6/in6.c	2008/10/03 07:59:20	1.30
@@ -1784,6 +1784,34 @@ in6ifa_ifpwithaddr(struct ifnet *ifp, st
 }
 
 /*
+ * find the internet address on a given interface corresponding to a neighbor's
+ * address.
+ */
+struct in6_ifaddr *
+in6ifa_ifplocaladdr(const struct ifnet *ifp, const struct in6_addr *addr)
+{
+	struct ifaddr *ifa;
+	struct in6_ifaddr *ia;
+	struct ifaddr_container *ifac;
+
+	TAILQ_FOREACH(ifac, &ifp->if_addrheads[mycpuid], ifa_link) {
+		ifa = ifac->ifa;
+
+		if (ifa->ifa_addr == NULL)
+			continue;	/* just for safety */
+		if (ifa->ifa_addr->sa_family != AF_INET6)
+			continue;
+		ia = (struct in6_ifaddr *)ifa;
+		if (IN6_ARE_MASKED_ADDR_EQUAL(addr,
+				&ia->ia_addr.sin6_addr,
+				&ia->ia_prefixmask.sin6_addr))
+			return ia;
+	}
+
+	return NULL;
+}
+
+/*
  * Convert IP6 address to printable (loggable) representation.
  */
 static char digits[] = "0123456789abcdef";