rpc: expose graph synced status within GetInfo

lnrpc/rpc.proto

@@ -1343,6 +1343,9 @@ message GetInfoResponse {
 
     /// The color of the current node in hex code format
     string color = 17 [json_name = "color"];
+
+    // Whether we consider ourselves synced with the public channel graph.
+    bool synced_to_graph = 18 [json_name = "synced_to_graph"];
 }
 
 message Chain {

lnrpc/rpc.swagger.json

@@ -2218,6 +2218,11 @@
         "color": {
           "type": "string",
           "title": "/ The color of the current node in hex code format"
+        },
+        "synced_to_graph": {
+          "type": "boolean",
+          "format": "boolean",
+          "description": "Whether we consider ourselves synced with the public channel graph."
         }
       }
     },

rpcserver.go

@@ -2029,6 +2029,8 @@ func (r *rpcServer) GetInfo(ctx context.Context,
 		uris[i] = fmt.Sprintf("%s@%s", encodedIDPub, addr.String())
 	}
 
+	isGraphSynced := r.server.authGossiper.SyncManager().IsGraphSynced()
+
 	// TODO(roasbeef): add synced height n stuff
 	return &lnrpc.GetInfoResponse{
 		IdentityPubkey:      encodedIDPub,
@@ -2046,6 +2048,7 @@ func (r *rpcServer) GetInfo(ctx context.Context,
 		Color:               routing.EncodeHexColor(nodeAnn.RGBColor),
 		BestHeaderTimestamp: int64(bestHeaderTimestamp),
 		Version:             build.Version(),
+		SyncedToGraph:       isGraphSynced,
 	}, nil
 }