buildroute use lnd default

cmd/lncli/cmd_payments.go

@@ -17,7 +17,6 @@ import (
 	"github.com/btcsuite/btcd/btcutil"
 	"github.com/jedib0t/go-pretty/v6/table"
 	"github.com/jedib0t/go-pretty/v6/text"
-	"github.com/lightningnetwork/lnd/chainreg"
 	"github.com/lightningnetwork/lnd/lnrpc"
 	"github.com/lightningnetwork/lnd/lnrpc/routerrpc"
 	"github.com/lightningnetwork/lnd/lntypes"
@@ -1556,7 +1555,18 @@ var buildRouteCommand = cli.Command{
 	Name:     "buildroute",
 	Category: "Payments",
 	Usage:    "Build a route from a list of hop pubkeys.",
-	Action:   actionDecorator(buildRoute),
+	Description: `
+	Builds a sphinx route for the supplied hops (public keys). Make sure to
+	use a custom final_cltv_delta to create the route depending on the
+	restrictions in the invoice otherwise LND will use its default specified
+	via the bitcoin.timelockdelta setting (default 80).
+	If the final_cltv_delta mismatch you will likely see the error
+	INCORRECT_OR_UNKNOWN_PAYMENT_DETAILS returned by the receiving node.
+
+	Moreover a payment_addr has to be provided if the invoice supplied it as
+	well otherwise the payment will be rejected by the receiving node.
+	`,
+	Action: actionDecorator(buildRoute),
 	Flags: []cli.Flag{
 		cli.Int64Flag{
 			Name: "amt",
@@ -1566,8 +1576,8 @@ var buildRouteCommand = cli.Command{
 		cli.Int64Flag{
 			Name: "final_cltv_delta",
 			Usage: "number of blocks the last hop has to reveal " +
-				"the preimage",
-			Value: chainreg.DefaultBitcoinTimeLockDelta,
+				"the preimage; if not set the default lnd " +
+				"final_cltv_delta is used",
 		},
 		cli.StringFlag{
 			Name:  "hops",
@@ -1622,10 +1632,11 @@ func buildRoute(ctx *cli.Context) error {
 		payAddr []byte
 		err     error
 	)
+
 	if ctx.IsSet("payment_addr") {
 		payAddr, err = hex.DecodeString(ctx.String("payment_addr"))
 		if err != nil {
-			return fmt.Errorf("error parsing payment_addr: %v", err)
+			return fmt.Errorf("error parsing payment_addr: %w", err)
 		}
 	}
 

docs/release-notes/release-notes-0.18.0.md

@@ -148,6 +148,9 @@
   the ability to specify multiple outgoing channel ids for the `sendpayment`
   command.
 
+* [Use the default LND value in the buildroute rpc command for the
+  final cltv delta](https://github.com/lightningnetwork/lnd/pull/8387).
+
 ## Code Health
 
 * [Remove Litecoin code](https://github.com/lightningnetwork/lnd/pull/7867).

lnrpc/routerrpc/router.proto

@@ -124,6 +124,10 @@ service Router {
     BuildRoute builds a fully specified route based on a list of hop public
     keys. It retrieves the relevant channel policies from the graph in order to
     calculate the correct fees and time locks.
+    Note that LND will use its default final_cltv_delta if no value is supplied.
+    Make sure to add the correct final_cltv_delta depending on the invoice
+    restriction. Moreover the caller has to make sure to provide the
+    payment_addr if the route is paying an invoice which signaled it.
     */
     rpc BuildRoute (BuildRouteRequest) returns (BuildRouteResponse);
 

lnrpc/routerrpc/router.swagger.json

@@ -293,7 +293,7 @@
     },
     "/v2/router/route": {
       "post": {
-        "summary": "lncli: `buildroute`\nBuildRoute builds a fully specified route based on a list of hop public\nkeys. It retrieves the relevant channel policies from the graph in order to\ncalculate the correct fees and time locks.",
+        "summary": "lncli: `buildroute`\nBuildRoute builds a fully specified route based on a list of hop public\nkeys. It retrieves the relevant channel policies from the graph in order to\ncalculate the correct fees and time locks.\nNote that LND will use its default final_cltv_delta if no value is supplied.\nMake sure to add the correct final_cltv_delta depending on the invoice\nrestriction. Moreover the caller has to make sure to provide the\npayment_addr if the route is paying an invoice which signaled it.",
         "operationId": "Router_BuildRoute",
         "responses": {
           "200": {

lnrpc/routerrpc/router_server.go

@@ -999,6 +999,12 @@ func (s *Server) BuildRoute(ctx context.Context,
 		payAddr = &backingPayAddr
 	}
 
+	if req.FinalCltvDelta == 0 {
+		req.FinalCltvDelta = int32(
+			s.cfg.RouterBackend.DefaultFinalCltvDelta,
+		)
+	}
+
 	// Build the route and return it to the caller.
 	route, err := s.cfg.Router.BuildRoute(
 		amt, hops, outgoingChan, req.FinalCltvDelta, payAddr,