fix the lsps2 cltv delta check

It was wrongly assumed that the lsp had to enforce a cltv delta +2. It is
actually the recipient creating invoices with a cltv delta +2, but the LSP does
not have anything to do with that.

.github/workflows/integration_tests.yaml

@@ -153,7 +153,6 @@ jobs:
           testLsps2GetInfo,
           testLsps2Buy,
           testLsps2HappyFlow,
-          testLsps2Cltv,
           testLsps2NoBalance,
           testLsps2ZeroConfUtxo
         ]

itest/lspd_test.go

@@ -210,11 +210,6 @@ var allTestCases = []*testCase{
 		test:    testLsps2HappyFlow,
 		isLsps2: true,
 	},
-	{
-		name:    "testLsps2Cltv",
-		test:    testLsps2Cltv,
-		isLsps2: true,
-	},
 	{
 		name:    "testLsps2NoBalance",
 		test:    testLsps2NoBalance,

itest/lsps2_cltv_test.go

@@ -1,66 +0,0 @@
-package itest
-
-import (
-	"log"
-	"time"
-
-	"github.com/breez/lntest"
-	"github.com/breez/lspd/lsps2"
-	"github.com/stretchr/testify/assert"
-)
-
-func testLsps2Cltv(p *testParams) {
-	alice := lntest.NewClnNode(p.h, p.m, "Alice")
-	alice.Start()
-	alice.Fund(10000000)
-	p.lsp.LightningNode().Fund(10000000)
-
-	log.Print("Opening channel between Alice and the lsp")
-	channel := alice.OpenChannel(p.lsp.LightningNode(), &lntest.OpenChannelOptions{
-		AmountSat: publicChanAmount,
-	})
-	aliceLspScid := alice.WaitForChannelReady(channel)
-
-	log.Print("Connecting bob to lspd")
-	p.BreezClient().Node().ConnectPeer(p.lsp.LightningNode())
-
-	// Make sure everything is activated.
-	<-time.After(htlcInterceptorDelay)
-
-	log.Printf("Calling lsps2.get_info")
-	info := Lsps2GetInfo(p.BreezClient(), p.Lsp(), lsps2.GetInfoRequest{
-		Token: &WorkingToken,
-	})
-
-	outerAmountMsat := uint64(2100000)
-	innerAmountMsat := lsps2CalculateInnerAmountMsat(p.lsp, outerAmountMsat, info.OpeningFeeParamsMenu[0])
-	p.BreezClient().SetHtlcAcceptor(innerAmountMsat)
-
-	log.Printf("Calling lsps2.buy")
-	buyResp := Lsps2Buy(p.BreezClient(), p.Lsp(), lsps2.BuyRequest{
-		OpeningFeeParams: *info.OpeningFeeParamsMenu[0],
-		PaymentSizeMsat:  &outerAmountMsat,
-	})
-
-	log.Printf("Adding bob's invoices")
-	description := "Please pay me"
-	_, outerInvoice := GenerateLsps2Invoices(p.BreezClient(),
-		generateInvoicesRequest{
-			innerAmountMsat: innerAmountMsat,
-			outerAmountMsat: outerAmountMsat,
-			description:     description,
-			lsp:             p.lsp,
-		},
-		buyResp.JitChannelScid)
-
-	// TODO: Fix race waiting for htlc interceptor.
-	log.Printf("Waiting %v to allow htlc interceptor to activate.", htlcInterceptorDelay)
-	<-time.After(htlcInterceptorDelay)
-	log.Printf("Alice paying")
-	route := constructRoute(p.Lsp().LightningNode(), p.BreezClient().Node(), aliceLspScid, lntest.NewShortChanIDFromString(buyResp.JitChannelScid), outerAmountMsat)
-
-	// Increment the delay by one (should be incremented by 2), so the cltv delta is too little.
-	route.Hops[0].Delay++
-	_, err := alice.PayViaRoute(outerAmountMsat, outerInvoice.paymentHash, outerInvoice.paymentSecret, route)
-	assert.Contains(p.t, err.Error(), "WIRE_INCORRECT_CLTV_EXPIRY")
-}

lsps2/intercept_handler.go

@@ -278,9 +278,9 @@ func (i *Interceptor) processPart(payment *paymentState, part *partState) {
 		}
 	}
 
-	// Make sure the cltv delta is enough (actual cltv delta + 2).
+	// Make sure the cltv delta is enough.
 	if int64(part.req.IncomingExpiry)-int64(part.req.OutgoingExpiry) <
-		int64(i.config.TimeLockDelta)+2 {
+		int64(i.config.TimeLockDelta) {
 		i.failPart(payment, part, common.FAILURE_INCORRECT_CLTV_EXPIRY)
 		return
 	}

lsps2/intercept_test.go

@@ -314,13 +314,13 @@ func Test_NoMpp_AmtAboveMaximum(t *testing.T) {
 }
 
 // Asserts that a no-MPP+var-invoice mode payment fails when the cltv delta is
-// less than cltv delta + 2.
+// less than cltv delta.
 func Test_NoMpp_CltvDeltaBelowMinimum(t *testing.T) {
 	ctx, cancel := context.WithCancel(context.Background())
 	defer cancel()
 	i := setupInterceptor(ctx, nil)
 
-	res := i.Intercept(createPart(&part{cltvDelta: 145}))
+	res := i.Intercept(createPart(&part{cltvDelta: 143}))
 	assert.Equal(t, common.INTERCEPT_FAIL_HTLC_WITH_CODE, res.Action)
 	assert.Equal(t, common.FAILURE_INCORRECT_CLTV_EXPIRY, res.FailureCode)
 	assertEmpty(t, i)
@@ -533,13 +533,13 @@ func Test_Mpp_BadSecondPart_ThirdPartCompletes(t *testing.T) {
 }
 
 // Asserts that a MPP+fixed-invoice mode payment fails when the cltv delta is
-// less than cltv delta + 2.
+// less than cltv delta.
 func Test_Mpp_CltvDeltaBelowMinimum(t *testing.T) {
 	ctx, cancel := context.WithCancel(context.Background())
 	defer cancel()
 	i := setupInterceptor(ctx, &interceptP{store: mppStore()})
 
-	res := i.Intercept(createPart(&part{cltvDelta: 145}))
+	res := i.Intercept(createPart(&part{cltvDelta: 143}))
 	assert.Equal(t, common.INTERCEPT_FAIL_HTLC_WITH_CODE, res.Action)
 	assert.Equal(t, common.FAILURE_INCORRECT_CLTV_EXPIRY, res.FailureCode)
 	assertEmpty(t, i)