net: ip: route: Add support to search mcast route by iface

This commit adds the possibility to check for a multicast route on a
given interface

Signed-off-by: Cristian Bulacu <cristian.bulacu@nxp.com>

Author: Cristib05

subsys/net/ip/route.c

@@ -957,6 +957,30 @@ net_route_mcast_lookup(struct in6_addr *group)
 
 	return NULL;
 }
+
+struct net_route_entry_mcast *
+net_route_mcast_lookup_by_iface(struct in6_addr *group, struct net_if *iface)
+{
+	ARRAY_FOR_EACH_PTR(route_mcast_entries, route) {
+		if (!route->is_used) {
+			continue;
+		}
+
+		ARRAY_FOR_EACH(route->ifaces, i) {
+			if (!route->ifaces[i] || route->ifaces[i] != iface) {
+				continue;
+			}
+
+			if (net_ipv6_is_prefix(group->s6_addr,
+						route->group.s6_addr,
+						route->prefix_len)) {
+				return route;
+			}
+		}
+	}
+
+	return NULL;
+}
 #endif /* CONFIG_NET_ROUTE_MCAST */
 
 bool net_route_get_info(struct net_if *iface,

subsys/net/ip/route.h

@@ -272,6 +272,17 @@ bool net_route_mcast_del(struct net_route_entry_mcast *route);
 struct net_route_entry_mcast *
 net_route_mcast_lookup(struct in6_addr *group);
 
+/**
+ * @brief Lookup a multicast routing entry on a given interface.
+ *
+ * @param group IPv6 multicast group address
+ * @param iface Network interface to check
+ *
+ * @return Routing entry corresponding to this multicast group and interface.
+ */
+struct net_route_entry_mcast *
+net_route_mcast_lookup_by_iface(struct in6_addr *group, struct net_if *iface);
+
 /**
  * @brief Add an interface to multicast routing entry.
  *