itest: add testSendToRouteFailHTLCTimeout to check SendToRouteV2

itest/list_on_test.go

@@ -662,4 +662,8 @@ var allTestCases = []*lntest.TestCase{
 		Name:     "payment succeeded htlc remote swept",
 		TestFunc: testPaymentSucceededHTLCRemoteSwept,
 	},
+	{
+		Name:     "send to route failed htlc timeout",
+		TestFunc: testSendToRouteFailHTLCTimeout,
+	},
 }

itest/lnd_payment_test.go

@@ -19,6 +19,7 @@ import (
 	"github.com/lightningnetwork/lnd/lntest/rpc"
 	"github.com/lightningnetwork/lnd/lntest/wait"
 	"github.com/lightningnetwork/lnd/lntypes"
+	"github.com/lightningnetwork/lnd/lnwire"
 	"github.com/stretchr/testify/require"
 )
 
@@ -1211,3 +1212,219 @@ func sendPaymentInterceptAndCancel(ht *lntest.HarnessTest,
 	// Cancel the context, which will disconnect the above interceptor.
 	cancelInterceptor()
 }
+
+// testSendToRouteFailHTLCTimeout is similar to
+// testPaymentFailedHTLCLocalSwept. The only difference is the `SendPayment` is
+// replaced with `SendToRouteV2`. It checks that when an outgoing HTLC is timed
+// out and claimed onchain via the timeout path, the payment will be marked as
+// failed. This test creates a topology from Alice -> Bob, and let Alice send
+// payments to Bob. Bob then goes offline, such that Alice's outgoing HTLC will
+// time out. Alice will also be restarted to make sure resumed payments are
+// also marked as failed.
+func testSendToRouteFailHTLCTimeout(ht *lntest.HarnessTest) {
+	success := ht.Run("fail payment", func(t *testing.T) {
+		st := ht.Subtest(t)
+		runSendToRouteFailHTLCTimeout(st, false)
+	})
+	if !success {
+		return
+	}
+
+	ht.Run("fail resumed payment", func(t *testing.T) {
+		st := ht.Subtest(t)
+		runTestPaymentHTLCTimeout(st, true)
+	})
+}
+
+// runSendToRouteFailHTLCTimeout is the helper function that actually runs the
+// testSendToRouteFailHTLCTimeout.
+func runSendToRouteFailHTLCTimeout(ht *lntest.HarnessTest, restartAlice bool) {
+	// Set the feerate to be 10 sat/vb.
+	ht.SetFeeEstimate(2500)
+
+	// Open a channel with 100k satoshis between Alice and Bob with Alice
+	// being the sole funder of the channel.
+	chanAmt := btcutil.Amount(100_000)
+	openChannelParams := lntest.OpenChannelParams{
+		Amt: chanAmt,
+	}
+
+	// Create a two hop network: Alice -> Bob.
+	chanPoints, nodes := createSimpleNetwork(ht, nil, 2, openChannelParams)
+	chanPoint := chanPoints[0]
+	alice, bob := nodes[0], nodes[1]
+
+	// We now create two payments, one above dust and the other below dust,
+	// and we should see different behavior in terms of when the payment
+	// will be marked as failed due to the HTLC timeout.
+	//
+	// First, create random preimages.
+	preimage := ht.RandomPreimage()
+	dustPreimage := ht.RandomPreimage()
+
+	// Get the preimage hashes.
+	payHash := preimage.Hash()
+	dustPayHash := dustPreimage.Hash()
+
+	// Create an hold invoice for Bob which expects a payment of 10k
+	// satoshis from Alice.
+	const paymentAmt = 20_000
+	req := &invoicesrpc.AddHoldInvoiceRequest{
+		Value: paymentAmt,
+		Hash:  payHash[:],
+		// Use a small CLTV value so we can mine fewer blocks.
+		CltvExpiry: finalCltvDelta,
+	}
+	invoice := bob.RPC.AddHoldInvoice(req)
+
+	// Create another hold invoice for Bob which expects a payment of 1k
+	// satoshis from Alice.
+	const dustAmt = 1000
+	req = &invoicesrpc.AddHoldInvoiceRequest{
+		Value: dustAmt,
+		Hash:  dustPayHash[:],
+		// Use a small CLTV value so we can mine fewer blocks.
+		CltvExpiry: finalCltvDelta,
+	}
+	dustInvoice := bob.RPC.AddHoldInvoice(req)
+
+	// Construct a route to send the non-dust payment.
+	go func() {
+		// Query the route to send the payment.
+		routesReq := &lnrpc.QueryRoutesRequest{
+			PubKey:         bob.PubKeyStr,
+			Amt:            paymentAmt,
+			FinalCltvDelta: finalCltvDelta,
+		}
+		routes := alice.RPC.QueryRoutes(routesReq)
+		require.Len(ht, routes.Routes, 1)
+
+		route := routes.Routes[0]
+		require.Len(ht, route.Hops, 1)
+
+		// Modify the hop to include MPP info.
+		route.Hops[0].MppRecord = &lnrpc.MPPRecord{
+			PaymentAddr: invoice.PaymentAddr,
+			TotalAmtMsat: int64(
+				lnwire.NewMSatFromSatoshis(paymentAmt),
+			),
+		}
+
+		// Send the payment with the modified value.
+		req := &routerrpc.SendToRouteRequest{
+			PaymentHash: payHash[:],
+			Route:       route,
+		}
+
+		// Send the payment and expect no error.
+		attempt := alice.RPC.SendToRouteV2(req)
+		require.Equal(ht, lnrpc.HTLCAttempt_FAILED, attempt.Status)
+	}()
+
+	// Check that the payment is in-flight.
+	ht.AssertPaymentStatus(alice, preimage, lnrpc.Payment_IN_FLIGHT)
+
+	// Construct a route to send the dust payment.
+	go func() {
+		// Query the route to send the payment.
+		routesReq := &lnrpc.QueryRoutesRequest{
+			PubKey:         bob.PubKeyStr,
+			Amt:            dustAmt,
+			FinalCltvDelta: finalCltvDelta,
+		}
+		routes := alice.RPC.QueryRoutes(routesReq)
+		require.Len(ht, routes.Routes, 1)
+
+		route := routes.Routes[0]
+		require.Len(ht, route.Hops, 1)
+
+		// Modify the hop to include MPP info.
+		route.Hops[0].MppRecord = &lnrpc.MPPRecord{
+			PaymentAddr: dustInvoice.PaymentAddr,
+			TotalAmtMsat: int64(
+				lnwire.NewMSatFromSatoshis(dustAmt),
+			),
+		}
+
+		// Send the payment with the modified value.
+		req := &routerrpc.SendToRouteRequest{
+			PaymentHash: dustPayHash[:],
+			Route:       route,
+		}
+
+		// Send the payment and expect no error.
+		attempt := alice.RPC.SendToRouteV2(req)
+		require.Equal(ht, lnrpc.HTLCAttempt_FAILED, attempt.Status)
+	}()
+
+	// Check that the dust payment is in-flight.
+	ht.AssertPaymentStatus(alice, dustPreimage, lnrpc.Payment_IN_FLIGHT)
+
+	// Bob should have two incoming HTLC.
+	ht.AssertIncomingHTLCActive(bob, chanPoint, payHash[:])
+	ht.AssertIncomingHTLCActive(bob, chanPoint, dustPayHash[:])
+
+	// Alice should have two outgoing HTLCs.
+	ht.AssertOutgoingHTLCActive(alice, chanPoint, payHash[:])
+	ht.AssertOutgoingHTLCActive(alice, chanPoint, dustPayHash[:])
+
+	// Let Bob go offline.
+	ht.Shutdown(bob)
+
+	// We'll now mine enough blocks to trigger Alice to broadcast her
+	// commitment transaction due to the fact that the HTLC is about to
+	// timeout. With the default outgoing broadcast delta of zero, this
+	// will be the same height as the htlc expiry height.
+	numBlocks := padCLTV(
+		uint32(req.CltvExpiry - lncfg.DefaultOutgoingBroadcastDelta),
+	)
+	ht.MineEmptyBlocks(int(numBlocks - 1))
+
+	// Restart Alice if requested.
+	if restartAlice {
+		// Restart Alice to test the resumed payment is canceled.
+		ht.RestartNode(alice)
+	}
+
+	// We now subscribe to the payment status.
+	payStream := alice.RPC.TrackPaymentV2(payHash[:])
+	dustPayStream := alice.RPC.TrackPaymentV2(dustPayHash[:])
+
+	// Mine a block to confirm Alice's closing transaction.
+	ht.MineBlocksAndAssertNumTxes(1, 1)
+
+	// Now the channel is closed, we expect different behaviors based on
+	// whether the HTLC is a dust. For dust payment, it should be failed
+	// now as the HTLC won't go onchain. For non-dust payment, it should
+	// still be inflight. It won't be marked as failed unless the outgoing
+	// HTLC is resolved onchain.
+	//
+	// Check that the dust payment is failed in both the stream and DB.
+	ht.AssertPaymentStatus(alice, dustPreimage, lnrpc.Payment_FAILED)
+	ht.AssertPaymentStatusFromStream(dustPayStream, lnrpc.Payment_FAILED)
+
+	// Check that the non-dust payment is still in-flight.
+	//
+	// NOTE: we don't check the payment status from the stream here as
+	// there's no new status being sent.
+	ht.AssertPaymentStatus(alice, preimage, lnrpc.Payment_IN_FLIGHT)
+
+	// We now have two possible cases for the non-dust payment:
+	// - Bob stays offline, and Alice will sweep her outgoing HTLC, which
+	//   makes the payment failed.
+	// - Bob comes back online, and claims the HTLC on Alice's commitment
+	//   via direct preimage spend, hence racing against Alice onchain. If
+	//   he succeeds, Alice should mark the payment as succeeded.
+	//
+	// TODO(yy): test the second case once we have the RPC to clean
+	// mempool.
+
+	// Since Alice's force close transaction has been confirmed, she should
+	// sweep her outgoing HTLC in next block.
+	ht.MineBlocksAndAssertNumTxes(2, 1)
+
+	// We expect the non-dust payment to marked as failed in Alice's
+	// database and also from her stream.
+	ht.AssertPaymentStatus(alice, preimage, lnrpc.Payment_FAILED)
+	ht.AssertPaymentStatusFromStream(payStream, lnrpc.Payment_FAILED)
+}