Merge pull request #9023 from ellemouton/testHTLCPersistenceAcrossRestart

lnwallet: correctly set UpdateAddHTLC.BlindingPoint on reload from disk

Author: guggero

docs/release-notes/release-notes-0.18.3.md

@@ -59,7 +59,11 @@ commitment when the channel was force closed.
 
 * We'll now always send [channel updates to our remote peer for open
   channels](https://github.com/lightningnetwork/lnd/pull/8963).
-
+ 
+* [Fix a bug](https://github.com/lightningnetwork/lnd/pull/9023) that would
+  cause UpdateAddHTLC message with blinding point fields to not be re-forwarded
+  correctly on restart.
+ 
 # New Features
 ## Functional Enhancements
 ## RPC Additions

itest/list_on_test.go

@@ -578,6 +578,10 @@ var allTestCases = []*lntest.TestCase{
 		Name:     "update pending open channels",
 		TestFunc: testUpdateOnPendingOpenChannels,
 	},
+	{
+		Name:     "blinded payment htlc re-forward",
+		TestFunc: testBlindedPaymentHTLCReForward,
+	},
 	{
 		Name:     "query blinded route",
 		TestFunc: testQueryBlindedRoutes,

itest/lnd_route_blinding_test.go

@@ -1424,3 +1424,68 @@ func testMPPToMultipleBlindedPaths(ht *lntest.HarnessTest) {
 		ht.AssertNumWaitingClose(hn, 0)
 	}
 }
+
+// testBlindedPaymentHTLCReForward tests that an UpdateAddHTLC message is
+// correctly persisted, reloaded and resent to the next peer on restart in the
+// case where the sending peer does not get a chance to send the message before
+// restarting. This test specifically tests that this is done correctly for
+// a blinded path payment since this adds a new blinding point field to
+// UpdateAddHTLC which we need to ensure gets included in the message on
+// restart.
+func testBlindedPaymentHTLCReForward(ht *lntest.HarnessTest) {
+	// Setup a test case.
+	ctx, testCase := newBlindedForwardTest(ht)
+	defer testCase.cleanup()
+
+	// Set up network with carol interceptor.
+	testCase.setupNetwork(ctx, true)
+
+	// Let dave create invoice.
+	blindedPaymentPath := testCase.buildBlindedPath()
+	route := testCase.createRouteToBlinded(10_000_000, blindedPaymentPath)
+
+	// Once our interceptor is set up, we can send the blinded payment.
+	hash := sha256.Sum256(testCase.preimage[:])
+	sendReq := &routerrpc.SendToRouteRequest{
+		PaymentHash: hash[:],
+		Route:       route,
+	}
+
+	// In a goroutine, we let Alice pay the invoice from dave.
+	done := make(chan struct{})
+	go func() {
+		defer close(done)
+
+		htlcAttempt, err := testCase.ht.Alice.RPC.Router.SendToRouteV2(
+			ctx, sendReq,
+		)
+		require.NoError(testCase.ht, err)
+		require.Equal(
+			testCase.ht, lnrpc.HTLCAttempt_SUCCEEDED,
+			htlcAttempt.Status,
+		)
+	}()
+
+	// Wait for the HTLC to be active on Alice and Bob's channels.
+	ht.AssertOutgoingHTLCActive(ht.Alice, testCase.channels[0], hash[:])
+	ht.AssertOutgoingHTLCActive(ht.Bob, testCase.channels[1], hash[:])
+
+	// Intercept the forward on Carol's link. At this point, we know she
+	// has received the HTLC and so will persist this packet.
+	_, err := testCase.carolInterceptor.Recv()
+	require.NoError(ht, err)
+
+	// Now, restart Carol. This time, don't require an interceptor. This
+	// means that Carol should load up any previously persisted
+	// UpdateAddHTLC messages and continue the processing of them.
+	ht.RestartNodeWithExtraArgs(
+		testCase.carol, []string{"--bitcoin.timelockdelta=18"},
+	)
+
+	// Now, wait for the payment to complete.
+	select {
+	case <-done:
+	case <-time.After(defaultTimeout):
+		require.Fail(ht, "timeout waiting for sending payment")
+	}
+}

lnwallet/channel.go

@@ -205,7 +205,7 @@ func PayDescsFromRemoteLogUpdates(chanID lnwire.ShortChannelID, height uint64,
 					Height: height,
 					Index:  uint16(i),
 				},
-				BlindingPoint: pd.BlindingPoint,
+				BlindingPoint: wireMsg.BlindingPoint,
 			}
 			pd.OnionBlob = make([]byte, len(wireMsg.OnionBlob))
 			copy(pd.OnionBlob[:], wireMsg.OnionBlob[:])