[telemetry] add more information about external routes

This commit removed `NodeDivergenceInfo` and added `ExternalRoutes`
messaged, to make it standalone.

The `ExternalRoutes` has three bool fields:
 - `has_default_route_added`: if leader network data has route ::/0
 - `has_ula_route_added`: if leader network data has route fc00::/7
 - `has_others_route_added`: if leader network has others route

src/common/types.hpp

@@ -387,6 +387,14 @@ class Ip6Prefix
      */
     bool IsDefaultRoutePrefix(void) const { return (*this == Ip6Prefix("::", 0)); }
 
+    /**
+     * This method checks if the object is the ULA prefix ("fc00::/7")
+     *
+     * @returns true if the object is the ULA prefix, false otherwise.
+     *
+     */
+    bool IsUlaPrefix(void) const { return (*this == Ip6Prefix("fc00::", 7)); }
+
     Ip6Address mPrefix; ///< The IPv6 prefix.
     uint8_t    mLength; ///< The IPv6 prefix length (in bits).
 };

src/proto/thread_telemetry.proto

@@ -496,14 +496,17 @@ message TelemetryData {
     optional uint32 global_unicast_address_count = 7;
   }
 
-  // infomation on divergent BRs resulted from multi-AIL
-  // TODO: add more fields to this message to provide more information
-  message NodeDivergenceInfo {
-    // Indicate whether the BR's external route is published
-    optional bool route_ail = 1;
+  // Message to indicate the information of external routes in network data.
+  message ExternalRoutes {
+    // Indicates whether the a zero-length prefix (::/0) added from this BR
+    optional bool has_default_route_added = 1;
 
-    // Indicate whether the BR's external route is published as default route
-    optional bool route_default = 2;
+    // Indicates whether the a ULA prefix (fc00::/7) added from this BR
+    optional bool has_ula_route_added = 2;
+
+    // Indicates whether the other prefixes (other than "::/0" or "fc00::/7") added
+    // from this BR. (BR is a managed infrastructure router).
+    optional bool has_others_route_added = 3;
   }
 
   message WpanBorderRouter {
@@ -543,8 +546,8 @@ message TelemetryData {
     // Information about the infra link
     optional InfraLinkInfo infra_link_info = 12;
 
-    // Information about the node divergence (multi-AIL)
-    optional NodeDivergenceInfo node_divergence_info = 13;
+    // Information about the external routes in network data.
+    optional ExternalRoutes external_route_info = 13;
   }
 
   message RcpStabilityStatistics {

src/utils/thread_helper.cpp

@@ -921,10 +921,11 @@ void ThreadHelper::DetachGracefullyCallback(void)
 
 #if OTBR_ENABLE_TELEMETRY_DATA_API
 #if OTBR_ENABLE_BORDER_ROUTING
-void ThreadHelper::GetNodeDivergenceInfo(threadnetwork::TelemetryData_NodeDivergenceInfo *aNodeDivergenceInfo)
+void ThreadHelper::GetExternalRouteInfo(threadnetwork::TelemetryData_ExternalRoutes *aExternalRouteInfo)
 {
-    bool      isExternalRouteAdded = false;
-    bool      isDefaultRouteAdded  = false;
+    bool      isDefaultRouteAdded = false;
+    bool      isUlaRouteAdded     = false;
+    bool      isOthersRouteAdded  = false;
     Ip6Prefix prefix;
     uint16_t  rloc16 = otThreadGetRloc16(mInstance);
 
@@ -938,18 +939,24 @@ void ThreadHelper::GetNodeDivergenceInfo(threadnetwork::TelemetryData_NodeDiverg
             continue;
         }
 
-        isExternalRouteAdded = true;
-
         prefix.Set(config.mPrefix);
         if (prefix.IsDefaultRoutePrefix())
         {
             isDefaultRouteAdded = true;
-            break;
+        }
+        else if (prefix.IsUlaPrefix())
+        {
+            isUlaRouteAdded = true;
+        }
+        else
+        {
+            isOthersRouteAdded = true;
         }
     }
 
-    aNodeDivergenceInfo->set_route_ail(isExternalRouteAdded);
-    aNodeDivergenceInfo->set_route_default(isDefaultRouteAdded);
+    aExternalRouteInfo->set_has_default_route_added(isDefaultRouteAdded);
+    aExternalRouteInfo->set_has_ula_route_added(isUlaRouteAdded);
+    aExternalRouteInfo->set_has_others_route_added(isOthersRouteAdded);
 }
 #endif // OTBR_ENABLE_BORDER_ROUTING
 
@@ -1315,8 +1322,9 @@ otError ThreadHelper::RetrieveTelemetryData(Mdns::Publisher *aPublisher, threadn
         }
         // End of InfraLinkInfo section.
 
-        // NodeDivergenceInfo section
-        GetNodeDivergenceInfo(wpanBorderRouter->mutable_node_divergence_info());
+        // ExternalRoutes section
+        GetExternalRouteInfo(wpanBorderRouter->mutable_external_route_info());
+
 #endif
 
 #if OTBR_ENABLE_SRP_ADVERTISING_PROXY

src/utils/thread_helper.hpp

@@ -303,7 +303,7 @@ class ThreadHelper
     void ActiveDatasetChangedCallback(void);
 
 #if OTBR_ENABLE_TELEMETRY_DATA_API && OTBR_ENABLE_BORDER_ROUTING
-    void GetNodeDivergenceInfo(threadnetwork::TelemetryData_NodeDivergenceInfo *aNodeDivergenceInfo);
+    void GetExternalRouteInfo(threadnetwork::TelemetryData_ExternalRoutes *aExternalRouteInfo);
 #endif
 
     otInstance *mInstance;