net: ip: Introduce mesh_local flag

include/net/net_if.h

@@ -75,7 +75,10 @@ struct net_if_addr {
 	/** Is this IP address used or not */
 	u8_t is_used : 1;
 
-	u8_t _unused : 6;
+	/** Is this IP address usage limited to the subnet (mesh) or not */
+	u8_t is_mesh_local : 1;
+
+	u8_t _unused : 5;
 };
 
 /**

subsys/net/ip/net_if.c

@@ -1970,6 +1970,13 @@ static struct in6_addr *net_if_ipv6_get_best_match(struct net_if *iface,
 
 		len = get_diff_ipv6(dst, &ipv6->unicast[i].address.in6_addr);
 		if (len >= *best_so_far) {
+			/* Mesh local address can only be selected for the same
+			 * subnet.
+			 */
+			if (ipv6->unicast[i].is_mesh_local && len < 64) {
+				continue;
+			}
+
 			*best_so_far = len;
 			src = &ipv6->unicast[i].address.in6_addr;
 		}

subsys/net/ip/net_shell.c

@@ -348,11 +348,12 @@ static void iface_cb(struct net_if *iface, void *user_data)
 			continue;
 		}
 
-		PR("\t%s %s %s%s\n",
+		PR("\t%s %s %s%s%s\n",
 		   net_sprint_ipv6_addr(&unicast->address.in6_addr),
 		   addrtype2str(unicast->addr_type),
 		   addrstate2str(unicast->addr_state),
-		   unicast->is_infinite ? " infinite" : "");
+		   unicast->is_infinite ? " infinite" : "",
+		   unicast->is_mesh_local ? " meshlocal" : "");
 		count++;
 	}
 

subsys/net/l2/openthread/openthread_utils.c

@@ -12,6 +12,7 @@ LOG_MODULE_DECLARE(net_l2_openthread, CONFIG_OPENTHREAD_L2_LOG_LEVEL);
 #include <net/openthread.h>
 
 #include <openthread/ip6.h>
+#include <openthread/thread.h>
 
 #include "openthread_utils.h"
 
@@ -25,6 +26,15 @@ static bool is_anycast_locator(const otNetifAddress *address)
 	       address->mAddress.mFields.m8[14] == ALOC16_MASK;
 }
 
+static bool is_mesh_local(struct openthread_context *context,
+			  const u8_t *address)
+{
+	const otMeshLocalPrefix *ml_prefix =
+				otThreadGetMeshLocalPrefix(context->instance);
+
+	return (memcmp(address, ml_prefix->m8, sizeof(ml_prefix)) == 0);
+}
+
 int pkt_list_add(struct openthread_context *context, struct net_pkt *pkt)
 {
 	u16_t i_idx = context->pkt_list_in_idx;
@@ -77,6 +87,7 @@ void pkt_list_remove_last(struct openthread_context *context)
 void add_ipv6_addr_to_zephyr(struct openthread_context *context)
 {
 	const otNetifAddress *address;
+	struct net_if_addr *if_addr;
 
 	for (address = otIp6GetUnicastAddresses(context->instance);
 	     address; address = address->mNext) {
@@ -94,9 +105,18 @@ void add_ipv6_addr_to_zephyr(struct openthread_context *context)
 				       buf, sizeof(buf))));
 		}
 
-		net_if_ipv6_addr_add(context->iface,
-				     (struct in6_addr *)(&address->mAddress),
-				     NET_ADDR_ANY, 0);
+		if_addr = net_if_ipv6_addr_add(
+					context->iface,
+					(struct in6_addr *)(&address->mAddress),
+					NET_ADDR_AUTOCONF, 0);
+
+		if (if_addr == NULL) {
+			NET_ERR("Cannot add OpenThread unicast address");
+			continue;
+		}
+
+		if_addr->is_mesh_local = is_mesh_local(
+					context, address->mAddress.mFields.m8);
 	}
 }
 
@@ -124,6 +144,9 @@ void add_ipv6_addr_to_ot(struct openthread_context *context)
 		}
 	}
 
+	ipv6->unicast[i].is_mesh_local = is_mesh_local(
+			context, ipv6->unicast[i].address.in6_addr.s6_addr);
+
 	addr.mValid = true;
 	addr.mPreferred = true;
 	addr.mPrefixLength = 64;