create multicast forward check for PBBR

Author: Mika Tervonen

source/6LoWPAN/Thread/thread_bbr_api.c

@@ -517,6 +517,34 @@ static int thread_border_relay_to_leader_cb(int8_t service_id, uint8_t source_ad
 }
 
 #ifdef HAVE_THREAD_BORDER_ROUTER
+static bool thread_bbr_default_route_exists(struct protocol_interface_info_entry *cur, uint8_t prefix_ptr[8])
+{
+    uint16_t rloc16 = mac_helper_mac16_address_get(cur);
+    ns_list_foreach(thread_network_data_prefix_cache_entry_t, prefix, &cur->thread_info->networkDataStorage.localPrefixList) {
+
+        if (prefix_ptr &&
+                (prefix->servicesPrefixLen != 64 ||
+                 memcmp(prefix_ptr, prefix->servicesPrefix, 8) != 0)) {
+            // Only matching prefixes are counted
+            continue;
+        }
+
+        ns_list_foreach(thread_network_server_data_entry_t, br, &prefix->borderRouterList) {
+            if (br->routerID == 0xfffe) {
+                continue;
+            }
+            if (!br->P_default_route) {
+                continue;
+            }
+            if (rloc16 != br->routerID) {
+                // different default route exists
+                return true;
+            }
+        }
+    }
+    return false;
+}
+
 static bool thread_bbr_i_host_prefix(struct protocol_interface_info_entry *cur, uint8_t prefix_ptr[8], uint8_t *br_count, bool *i_am_lowest)
 {
     bool i_host_this_prefix = false;
@@ -600,14 +628,15 @@ static void thread_bbr_network_data_send(thread_bbr_t *this, uint8_t prefix[8],
     this->br_info_published = true;
 }
 
-static void thread_bbr_routing_enable(thread_bbr_t *this)
+static void thread_bbr_routing_enable(thread_bbr_t *this, bool multicast_routing_enabled)
 {
     if (this->routing_enabled) {
         return;
     }
     tr_info("br: enable routing");
     // Start multicast proxying
-    multicast_fwd_set_forwarding(this->interface_id, true);
+    // We do not enable multicast forwarding as there is other default router present in network
+    multicast_fwd_set_forwarding(this->interface_id, multicast_routing_enabled);
     this->routing_enabled = true;
 }
 
@@ -663,7 +692,13 @@ static void thread_bbr_status_check(thread_bbr_t *this, uint32_t seconds)
 
     // Check from network data are we currently BR or not and change routing state
     if (this->br_hosted) {
-        thread_bbr_routing_enable(this);
+
+        //If there is a default router present in any prefix other than us we do not forward multicast
+        //This prevents multicasts to different interfaces where Thread Mesh is forwarder
+        bool forward_multicast = !thread_bbr_default_route_exists(cur, NULL);
+        thread_extension_bbr_mcast_fwd_check(cur->id, &forward_multicast);
+
+        thread_bbr_routing_enable(this, forward_multicast);
     } else {
         thread_bbr_routing_disable(this);
     }

source/6LoWPAN/Thread/thread_extension_bbr.c

@@ -1526,4 +1526,26 @@ void thread_extension_bbr_status_override_set(uint8_t dua_status, uint8_t dua_co
     ba_response_status_count = ba_failure_count;
 }
 
+void thread_extension_bbr_mcast_fwd_check(int8_t interface_id, bool *multicast_fwd)
+{
+    thread_pbbr_t *this = thread_bbr_find_by_interface(interface_id);
+    protocol_interface_info_entry_t *cur = protocol_stack_interface_info_get_by_id(this->interface_id);
+
+    if (!cur || !this || multicast_fwd) {
+        return;
+    }
+
+    if (this->pbbr_started) {
+        //We are Primary BBR so we always forward multicast
+        *multicast_fwd = true;
+        return;
+    }
+    if (0 == thread_extension_primary_bbr_get(cur, NULL, NULL, NULL, NULL)) {
+        // We are secondary BBR we newer forward
+        *multicast_fwd = false;
+        return;
+    }
+    // No modification made
+}
+
 #endif //HAVE_THREAD_BORDER_ROUTER && HAVE_THREAD_V2

source/6LoWPAN/Thread/thread_extension_bbr.h

@@ -60,6 +60,7 @@ void thread_extension_bbr_old_partition_data_clean(int8_t interface_id);
 void thread_extension_bbr_status_override_get(uint8_t *dua_status, uint8_t *dua_count, uint8_t *ba_failure_count);
 void thread_extension_bbr_status_override_set(uint8_t dua_status, uint8_t dua_count, uint8_t ba_failure_count);
 void thread_extension_status_override_count_set(uint8_t value);
+void thread_extension_bbr_mcast_fwd_check(int8_t interface_id, bool *multicast_fwd);
 
 
 #else
@@ -77,6 +78,7 @@ void thread_extension_status_override_count_set(uint8_t value);
 #define thread_extension_bbr_status_override_get(dua_status, dua_count, ba_failure_count);
 #define thread_extension_bbr_status_override_set(dua_status, dua_count, ba_failure_count);
 #define thread_extension_status_override_count_set(value)
+#define thread_extension_bbr_mcast_fwd_check(interface_id, multicast_fwd)
 #endif
 
 #ifdef __cplusplus