Merge pull request #2521 from joostjager/sendtosingleroute

lnrpc: deprecate SendToRoute with more than one route

lnrpc/rpc.proto

@@ -781,8 +781,16 @@ message SendToRouteRequest {
     /// An optional hex-encoded payment hash to be used for the HTLC.
     string payment_hash_string = 2;
 
-    /// The set of routes that should be used to attempt to complete the payment.
-    repeated Route routes = 3;
+    /**
+    Deprecated. The set of routes that should be used to attempt to complete the
+    payment. The possibility to pass in multiple routes is deprecated and 
+    instead the single route field below should be used in combination with the 
+    streaming variant of SendToRoute.
+    */
+    repeated Route routes = 3 [deprecated = true];
+
+    /// Route that should be used to attempt to complete the payment.
+    Route route = 4;
 }
 
 message ChannelPoint {

lnrpc/rpc.swagger.json

@@ -2911,7 +2911,11 @@
           "items": {
             "$ref": "#/definitions/lnrpcRoute"
           },
-          "description": "/ The set of routes that should be used to attempt to complete the payment."
+          "description": "*\nDeprecated. The set of routes that should be used to attempt to complete the\npayment. The possibility to pass in multiple routes is deprecated and \ninstead the single route field below should be used in combination with the \nstreaming variant of SendToRoute."
+        },
+        "route": {
+          "$ref": "#/definitions/lnrpcRoute",
+          "description": "/ Route that should be used to attempt to complete the payment."
         }
       }
     },

rpcserver.go

@@ -2565,25 +2565,7 @@ func (r *rpcServer) SendToRoute(stream lnrpc.Lightning_SendToRouteServer) error
 
 			graph := r.server.chanDB.ChannelGraph()
 
-			if len(req.Routes) == 0 {
-				return nil, fmt.Errorf("unable to send, no routes provided")
-			}
-
-			routes := make([]*routing.Route, len(req.Routes))
-			for i, rpcroute := range req.Routes {
-				route, err := r.unmarshallRoute(rpcroute, graph)
-				if err != nil {
-					return nil, err
-				}
-				routes[i] = route
-			}
-
-			return &rpcPaymentRequest{
-				SendRequest: &lnrpc.SendRequest{
-					PaymentHash: req.PaymentHash,
-				},
-				routes: routes,
-			}, nil
+			return unmarshallSendToRouteRequest(req, graph)
 		},
 		send: func(r *lnrpc.SendResponse) error {
 			// Calling stream.Send concurrently is not safe.
@@ -2594,6 +2576,43 @@ func (r *rpcServer) SendToRoute(stream lnrpc.Lightning_SendToRouteServer) error
 	})
 }
 
+// unmarshallSendToRouteRequest unmarshalls an rpc sendtoroute request
+func unmarshallSendToRouteRequest(req *lnrpc.SendToRouteRequest,
+	graph *channeldb.ChannelGraph) (*rpcPaymentRequest, error) {
+
+	switch {
+	case len(req.Routes) == 0 && req.Route == nil:
+		return nil, fmt.Errorf("unable to send, no routes provided")
+	case len(req.Routes) > 0 && req.Route != nil:
+		return nil, fmt.Errorf("cannot use both route and routes field")
+	}
+
+	var routes []*routing.Route
+	if len(req.Routes) > 0 {
+		routes = make([]*routing.Route, len(req.Routes))
+		for i, rpcroute := range req.Routes {
+			route, err := unmarshallRoute(rpcroute, graph)
+			if err != nil {
+				return nil, err
+			}
+			routes[i] = route
+		}
+	} else {
+		route, err := unmarshallRoute(req.Route, graph)
+		if err != nil {
+			return nil, err
+		}
+		routes = []*routing.Route{route}
+	}
+
+	return &rpcPaymentRequest{
+		SendRequest: &lnrpc.SendRequest{
+			PaymentHash: req.PaymentHash,
+		},
+		routes: routes,
+	}, nil
+}
+
 // rpcPaymentIntent is a small wrapper struct around the of values we can
 // receive from a client over RPC if they wish to send a payment. We'll either
 // extract these fields from a payment request (which may include routing
@@ -3027,21 +3046,12 @@ func (r *rpcServer) SendToRouteSync(ctx context.Context,
 
 	graph := r.server.chanDB.ChannelGraph()
 
-	routes := make([]*routing.Route, len(req.Routes))
-	for i, route := range req.Routes {
-		route, err := r.unmarshallRoute(route, graph)
-		if err != nil {
-			return nil, err
-		}
-		routes[i] = route
+	paymentRequest, err := unmarshallSendToRouteRequest(req, graph)
+	if err != nil {
+		return nil, err
 	}
 
-	return r.sendPaymentSync(ctx, &rpcPaymentRequest{
-		SendRequest: &lnrpc.SendRequest{
-			PaymentHashString: req.PaymentHashString,
-		},
-		routes: routes,
-	})
+	return r.sendPaymentSync(ctx, paymentRequest)
 }
 
 // sendPaymentSync is the synchronous variant of sendPayment. It will block and
@@ -4024,7 +4034,7 @@ func unmarshallHop(graph *channeldb.ChannelGraph, hop *lnrpc.Hop,
 
 // unmarshallRoute unmarshalls an rpc route. For hops that don't specify a
 // pubkey, the channel graph is queried.
-func (r *rpcServer) unmarshallRoute(rpcroute *lnrpc.Route,
+func unmarshallRoute(rpcroute *lnrpc.Route,
 	graph *channeldb.ChannelGraph) (*routing.Route, error) {
 
 	sourceNode, err := graph.SourceNode()