lnd.xprv/lntest/itest/lnd_multi-hop_htlc_receiver_chain_claim_test.go

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package itest
import (
"context"
"time"
"github.com/btcsuite/btcd/wire"
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"github.com/lightningnetwork/lnd/lncfg"
"github.com/lightningnetwork/lnd/lnrpc"
"github.com/lightningnetwork/lnd/lnrpc/invoicesrpc"
"github.com/lightningnetwork/lnd/lnrpc/routerrpc"
"github.com/lightningnetwork/lnd/lntest"
"github.com/lightningnetwork/lnd/lntest/wait"
"github.com/lightningnetwork/lnd/lntypes"
"github.com/stretchr/testify/require"
)
// testMultiHopReceiverChainClaim tests that in the multi-hop setting, if the
// receiver of an HTLC knows the preimage, but wasn't able to settle the HTLC
// off-chain, then it goes on chain to claim the HTLC uing the HTLC success
// transaction. In this scenario, the node that sent the outgoing HTLC should
// extract the preimage from the sweep transaction, and finish settling the
// HTLC backwards into the route.
func testMultiHopReceiverChainClaim(net *lntest.NetworkHarness, t *harnessTest,
alice, bob *lntest.HarnessNode, c commitType) {
ctxb := context.Background()
// First, we'll create a three hop network: Alice -> Bob -> Carol, with
// Carol refusing to actually settle or directly cancel any HTLC's
// self.
aliceChanPoint, bobChanPoint, carol := createThreeHopNetwork(
t, net, alice, bob, false, c,
)
// Clean up carol's node when the test finishes.
defer shutdownAndAssert(net, t, carol)
// With the network active, we'll now add a new hodl invoice at Carol's
// end. Make sure the cltv expiry delta is large enough, otherwise Bob
// won't send out the outgoing htlc.
const invoiceAmt = 100000
preimage := lntypes.Preimage{1, 2, 4}
payHash := preimage.Hash()
invoiceReq := &invoicesrpc.AddHoldInvoiceRequest{
Value: invoiceAmt,
CltvExpiry: 40,
Hash: payHash[:],
}
ctxt, cancel := context.WithTimeout(ctxb, defaultTimeout)
defer cancel()
carolInvoice, err := carol.AddHoldInvoice(ctxt, invoiceReq)
require.NoError(t.t, err)
// Now that we've created the invoice, we'll send a single payment from
// Alice to Carol. We won't wait for the response however, as Carol
// will not immediately settle the payment.
ctx, cancel := context.WithCancel(ctxb)
defer cancel()
_, err = alice.RouterClient.SendPaymentV2(
ctx, &routerrpc.SendPaymentRequest{
PaymentRequest: carolInvoice.PaymentRequest,
TimeoutSeconds: 60,
FeeLimitMsat: noFeeLimitMsat,
},
)
require.NoError(t.t, err)
// At this point, all 3 nodes should now have an active channel with
// the created HTLC pending on all of them.
nodes := []*lntest.HarnessNode{alice, bob, carol}
err = wait.NoError(func() error {
return assertActiveHtlcs(nodes, payHash[:])
}, defaultTimeout)
require.NoError(t.t, err)
// Wait for carol to mark invoice as accepted. There is a small gap to
// bridge between adding the htlc to the channel and executing the exit
// hop logic.
waitForInvoiceAccepted(t, carol, payHash)
restartBob, err := net.SuspendNode(bob)
require.NoError(t.t, err)
// Settle invoice. This will just mark the invoice as settled, as there
// is no link anymore to remove the htlc from the commitment tx. For
// this test, it is important to actually settle and not leave the
// invoice in the accepted state, because without a known preimage, the
// channel arbitrator won't go to chain.
ctx, cancel = context.WithTimeout(ctxb, defaultTimeout)
defer cancel()
_, err = carol.SettleInvoice(ctx, &invoicesrpc.SettleInvoiceMsg{
Preimage: preimage[:],
})
require.NoError(t.t, err)
// Increase the fee estimate so that the following force close tx will
// be cpfp'ed.
net.SetFeeEstimate(30000)
// Now we'll mine enough blocks to prompt carol to actually go to the
// chain in order to sweep her HTLC since the value is high enough.
// TODO(roasbeef): modify once go to chain policy changes
numBlocks := padCLTV(uint32(
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invoiceReq.CltvExpiry - lncfg.DefaultIncomingBroadcastDelta,
))
_, err = net.Miner.Node.Generate(numBlocks)
require.NoError(t.t, err)
// At this point, Carol should broadcast her active commitment
// transaction in order to go to the chain and sweep her HTLC. If there
// are anchors, Carol also sweeps hers.
expectedTxes := 1
if c == commitTypeAnchors {
expectedTxes = 2
}
_, err = getNTxsFromMempool(
net.Miner.Node, expectedTxes, minerMempoolTimeout,
)
require.NoError(t.t, err)
bobFundingTxid, err := lnrpc.GetChanPointFundingTxid(bobChanPoint)
require.NoError(t.t, err)
carolFundingPoint := wire.OutPoint{
Hash: *bobFundingTxid,
Index: bobChanPoint.OutputIndex,
}
// The commitment transaction should be spending from the funding
// transaction.
closingTx := getSpendingTxInMempool(
t, net.Miner.Node, minerMempoolTimeout, carolFundingPoint,
)
closingTxid := closingTx.TxHash()
// Confirm the commitment.
mineBlocks(t, net, 1, expectedTxes)
// Restart bob again.
err = restartBob()
require.NoError(t.t, err)
// After the force close transaction is mined, Carol should broadcast
// her second level HTLC transaction. Bob will broadcast a sweep tx to
// sweep his output in the channel with Carol. When Bob notices Carol's
// second level transaction in the mempool, he will extract the preimage
// and settle the HTLC back off-chain. Bob will also sweep his anchor,
// if present.
expectedTxes = 2
if c == commitTypeAnchors {
expectedTxes = 3
}
txes, err := getNTxsFromMempool(
net.Miner.Node, expectedTxes, minerMempoolTimeout,
)
require.NoError(t.t, err)
// All transactions should be spending from the commitment transaction.
assertAllTxesSpendFrom(t, txes, closingTxid)
// We'll now mine an additional block which should confirm both the
// second layer transactions.
_, err = net.Miner.Node.Generate(1)
require.NoError(t.t, err)
time.Sleep(time.Second * 4)
// TODO(roasbeef): assert bob pending state as well
// Carol's pending channel report should now show two outputs under
// limbo: her commitment output, as well as the second-layer claim
// output.
pendingChansRequest := &lnrpc.PendingChannelsRequest{}
ctxt, _ = context.WithTimeout(ctxb, defaultTimeout)
pendingChanResp, err := carol.PendingChannels(ctxt, pendingChansRequest)
require.NoError(t.t, err)
require.NotZero(t.t, len(pendingChanResp.PendingForceClosingChannels))
forceCloseChan := pendingChanResp.PendingForceClosingChannels[0]
require.NotZero(t.t, forceCloseChan.LimboBalance)
// The pending HTLC carol has should also now be in stage 2.
require.Len(t.t, forceCloseChan.PendingHtlcs, 1)
require.Equal(t.t, uint32(2), forceCloseChan.PendingHtlcs[0].Stage)
// Once the second-level transaction confirmed, Bob should have
// extracted the preimage from the chain, and sent it back to Alice,
// clearing the HTLC off-chain.
nodes = []*lntest.HarnessNode{alice}
err = wait.NoError(func() error {
return assertNumActiveHtlcs(nodes, 0)
}, defaultTimeout)
require.NoError(t.t, err)
// If we mine 4 additional blocks, then both outputs should now be
// mature.
_, err = net.Miner.Node.Generate(defaultCSV)
require.NoError(t.t, err)
// We should have a new transaction in the mempool.
_, err = waitForTxInMempool(net.Miner.Node, minerMempoolTimeout)
require.NoError(t.t, err)
// Finally, if we mine an additional block to confirm these two sweep
// transactions, Carol should not show a pending channel in her report
// afterwards.
_, err = net.Miner.Node.Generate(1)
require.NoError(t.t, err)
ctxt, _ = context.WithTimeout(ctxb, defaultTimeout)
err = waitForNumChannelPendingForceClose(ctxt, carol, 0, nil)
require.NoError(t.t, err)
// The invoice should show as settled for Carol, indicating that it was
// swept on-chain.
invoicesReq := &lnrpc.ListInvoiceRequest{}
invoicesResp, err := carol.ListInvoices(ctxb, invoicesReq)
require.NoError(t.t, err)
require.Len(t.t, invoicesResp.Invoices, 1)
invoice := invoicesResp.Invoices[0]
require.Equal(t.t, lnrpc.Invoice_SETTLED, invoice.State)
require.Equal(t.t, int64(invoiceAmt), invoice.AmtPaidSat)
// Finally, check that the Alice's payment is correctly marked
// succeeded.
ctxt, _ = context.WithTimeout(ctxt, defaultTimeout)
err = checkPaymentStatus(
ctxt, alice, preimage, lnrpc.Payment_SUCCEEDED,
)
require.NoError(t.t, err)
// We'll close out the channel between Alice and Bob, then shutdown
// carol to conclude the test.
ctxt, _ = context.WithTimeout(ctxb, channelCloseTimeout)
closeChannelAndAssertType(
ctxt, t, net, alice, aliceChanPoint,
false, false,
)
}