net: if: Join/leave pre-defined IPv6 multicast groups

When we setup the network interface, add predefined IPv6 multicast
groups into the network interface. When interface is taken down,
then leave all the multicast groups that joined.
See RFC 4291 ch 2.8 for details.

Change-Id: If17d3e8c75157a02aa93c92e2fb499619c1484cf
Signed-off-by: Jukka Rissanen <jukka.rissanen@linux.intel.com>

subsys/net/ip/net_if.c

@@ -246,6 +246,56 @@ struct net_if *net_if_get_default(void)
 
 #if defined(CONFIG_NET_IPV6)
 
+#if defined(CONFIG_NET_IPV6_MLD)
+static void join_mcast_allnodes(struct net_if *iface)
+{
+	struct in6_addr addr;
+
+	net_ipv6_addr_create_ll_allnodes_mcast(&addr);
+	net_ipv6_mld_join(iface, &addr);
+}
+
+static void join_mcast_solicit_node(struct net_if *iface,
+				    struct in6_addr *my_addr)
+{
+	struct in6_addr addr;
+
+	/* Join to needed multicast groups, RFC 4291 ch 2.8 */
+	net_ipv6_addr_create_solicited_node(my_addr, &addr);
+	net_ipv6_mld_join(iface, &addr);
+}
+
+static void leave_mcast_allnodes(struct net_if *iface)
+{
+	struct in6_addr addr;
+
+	net_ipv6_addr_create_ll_allnodes_mcast(&addr);
+	net_ipv6_mld_leave(iface, &addr);
+}
+
+static void leave_mcast_solicit_node_all(struct net_if *iface)
+{
+	struct in6_addr addr;
+	int i;
+
+	for (i = 0; i < NET_IF_MAX_IPV6_MADDR; i++) {
+		if (!iface->ipv6.mcast[i].is_used) {
+			continue;
+		}
+
+		net_ipv6_addr_create_solicited_node(
+			&iface->ipv6.mcast[i].address.in6_addr, &addr);
+
+		net_ipv6_mld_leave(iface, &addr);
+	}
+}
+#else
+#define join_mcast_allnodes(...)
+#define join_mcast_solicit_node(...)
+#define leave_mcast_allnodes(...)
+#define leave_mcast_solicit_node_all(...)
+#endif /* CONFIG_NET_IPV6_MLD */
+
 #if defined(CONFIG_NET_IPV6_DAD)
 #define DAD_TIMEOUT (MSEC_PER_SEC / 10)
 
@@ -271,6 +321,17 @@ static void dad_timeout(struct k_work *work)
 		 * in this case as the address is our own one.
 		 */
 		net_ipv6_nbr_rm(iface, &ifaddr->address.in6_addr);
+
+		/* We join the allnodes group from here so that we have
+		 * a link local address defined. If done from ifup(),
+		 * we would only get unspecified address as a source
+		 * address. The allnodes multicast group is only joined
+		 * once in this case as the net_ipv6_mcast_join() checks
+		 * if we have already joined.
+		 */
+		join_mcast_allnodes(iface);
+
+		join_mcast_solicit_node(iface, &ifaddr->address.in6_addr);
 	}
 }
 
@@ -1121,6 +1182,12 @@ uint32_t net_if_ipv6_calc_reachable_time(struct net_if *iface)
 		(MAX_RANDOM_FACTOR * iface->base_reachable_time -
 		 MIN_RANDOM_FACTOR * iface->base_reachable_time);
 }
+
+#else /* CONFIG_NET_IPV6 */
+#define join_mcast_allnodes(...)
+#define join_mcast_solicit_node(...)
+#define leave_mcast_allnodes(...)
+#define leave_mcast_solicit_node_all(...)
 #endif /* CONFIG_NET_IPV6 */
 
 #if defined(CONFIG_NET_IPV4)
@@ -1407,6 +1474,10 @@ done:
 #if defined(CONFIG_NET_IPV6_DAD)
 	NET_DBG("Starting DAD for iface %p", iface);
 	net_if_start_dad(iface);
+#else
+	/* Join the IPv6 multicast groups even if DAD is disabled */
+	join_mcast_allnodes(iface);
+	join_mcast_solicit_node(iface, &iface->ipv6.mcast[0].address.in6_addr);
 #endif
 
 #if defined(CONFIG_NET_IPV6_ND)
@@ -1425,6 +1496,12 @@ int net_if_down(struct net_if *iface)
 
 	NET_DBG("iface %p", iface);
 
+	/* FIXME: Make sure that the IPV6 mcast leave message
+	 * gets actually sent.
+	 */
+	leave_mcast_allnodes(iface);
+	leave_mcast_solicit_node_all(iface);
+
 	/* If the L2 does not support enable just clear the flag */
 	if (!iface->l2->enable) {
 		goto done;

tests/net/context/prj.conf

@@ -13,6 +13,7 @@ CONFIG_RANDOM_GENERATOR=y
 CONFIG_TEST_RANDOM_GENERATOR=y
 CONFIG_NET_IPV6_ND=n
 CONFIG_NET_IPV6_DAD=n
+CONFIG_NET_IPV6_MLD=n
 CONFIG_NET_NBUF_TX_COUNT=10
 CONFIG_NET_NBUF_RX_COUNT=5
 CONFIG_NET_NBUF_RX_DATA_COUNT=10

tests/net/iface/prj.conf

@@ -10,6 +10,7 @@ CONFIG_SYS_LOG_SHOW_COLOR=y
 CONFIG_RANDOM_GENERATOR=y
 CONFIG_TEST_RANDOM_GENERATOR=y
 CONFIG_NET_IPV6_DAD=n
+CONFIG_NET_IPV6_MLD=n
 CONFIG_NET_NBUF_TX_COUNT=10
 CONFIG_NET_NBUF_RX_COUNT=5
 CONFIG_NET_NBUF_RX_DATA_COUNT=10

tests/net/route/prj.conf

@@ -10,6 +10,7 @@ CONFIG_SYS_LOG_SHOW_COLOR=y
 CONFIG_RANDOM_GENERATOR=y
 CONFIG_TEST_RANDOM_GENERATOR=y
 CONFIG_NET_IPV6_DAD=n
+CONFIG_NET_IPV6_MLD=n
 CONFIG_NET_NBUF_TX_COUNT=10
 CONFIG_NET_NBUF_RX_COUNT=5
 CONFIG_NET_NBUF_RX_DATA_COUNT=5

tests/net/rpl/prj.conf

@@ -11,6 +11,7 @@ CONFIG_RANDOM_GENERATOR=y
 CONFIG_TEST_RANDOM_GENERATOR=y
 CONFIG_NET_IPV6_ND=n
 CONFIG_NET_IPV6_DAD=n
+CONFIG_NET_IPV6_MLD=n
 CONFIG_NET_IF_MCAST_IPV6_ADDR_COUNT=3
 CONFIG_NET_NBUF_TX_COUNT=10
 CONFIG_NET_NBUF_RX_COUNT=5