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

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package itest
import (
"context"
"fmt"
"github.com/btcsuite/btcd/wire"
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"github.com/lightningnetwork/lnd"
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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"
)
// testMultiHopHtlcLocalChainClaim tests that in a multi-hop HTLC scenario, if
// we force close a channel with an incoming HTLC, and later find out the
// preimage via the witness beacon, we properly settle the HTLC on-chain using
// the HTLC success transaction in order to ensure we don't lose any funds.
func testMultiHopHtlcLocalChainClaim(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, 3}
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)
// Increase the fee estimate so that the following force close tx will
// be cpfp'ed.
net.SetFeeEstimate(30000)
// At this point, Bob decides that he wants to exit the channel
// immediately, so he force closes his commitment transaction.
ctxt, _ = context.WithTimeout(ctxb, channelCloseTimeout)
bobForceClose := closeChannelAndAssertType(
ctxt, t, net, bob, aliceChanPoint, c == commitTypeAnchors, true,
)
// Alice will sweep her commitment output immediately. If there are
// anchors, Alice will also sweep hers.
expectedTxes := 1
if c == commitTypeAnchors {
expectedTxes = 2
}
_, err = waitForNTxsInMempool(
net.Miner.Node, expectedTxes, minerMempoolTimeout,
)
require.NoError(t.t, err)
// Suspend Bob to force Carol to go to chain.
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)
// We'll now mine enough blocks so Carol decides that she needs to go
// on-chain to claim the HTLC as Bob has been inactive.
numBlocks := padCLTV(uint32(invoiceReq.CltvExpiry -
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lncfg.DefaultIncomingBroadcastDelta))
_, err = net.Miner.Node.Generate(numBlocks)
require.NoError(t.t, err)
// Carol's commitment transaction should now be in the mempool. If there
// is an anchor, Carol will sweep that too.
_, err = waitForNTxsInMempool(
net.Miner.Node, expectedTxes, minerMempoolTimeout,
)
require.NoError(t.t, err)
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bobFundingTxid, err := lnd.GetChanPointFundingTxid(bobChanPoint)
require.NoError(t.t, err)
carolFundingPoint := wire.OutPoint{
Hash: *bobFundingTxid,
Index: bobChanPoint.OutputIndex,
}
// Look up the closing transaction. It should be spending from the
// funding transaction,
closingTx := getSpendingTxInMempool(
t, net.Miner.Node, minerMempoolTimeout, carolFundingPoint,
)
closingTxid := closingTx.TxHash()
// Mine a block that should confirm the commit tx, the anchor if present
// and the coinbase.
block := mineBlocks(t, net, 1, expectedTxes)[0]
require.Len(t.t, block.Transactions, expectedTxes+1)
assertTxInBlock(t, block, &closingTxid)
// Restart bob again.
err = restartBob()
require.NoError(t.t, err)
// After the force close transacion is mined, Carol should broadcast her
// second level HTLC transacion. Bob will broadcast a sweep tx to sweep
// his output in the channel with Carol. He can do this immediately, as
// the output is not timelocked since Carol was the one force closing.
// If there are anchors on the commitment, Bob will also sweep his
// anchor.
expectedTxes = 2
if c == commitTypeAnchors {
expectedTxes = 3
}
txes, err := getNTxsFromMempool(
net.Miner.Node, expectedTxes, minerMempoolTimeout,
)
require.NoError(t.t, err)
// Both Carol's second level transaction and Bob's sweep should be
// spending from the commitment transaction.
assertAllTxesSpendFrom(t, txes, closingTxid)
// At this point we suspend Alice to make sure she'll handle the
// on-chain settle after a restart.
restartAlice, err := net.SuspendNode(alice)
require.NoError(t.t, err)
// Mine a block to confirm the two transactions (+ the coinbase).
block = mineBlocks(t, net, 1, expectedTxes)[0]
require.Len(t.t, block.Transactions, expectedTxes+1)
var secondLevelMaturity uint32
switch c {
// If this is a channel of the anchor type, we will subtract one block
// from the default CSV, as the Sweeper will handle the input, and the Sweeper
// sweeps the input as soon as the lock expires.
case commitTypeAnchors:
secondLevelMaturity = defaultCSV - 1
// For non-anchor channel types, the nursery will handle sweeping the
// second level output, and it will wait one extra block before
// sweeping it.
default:
secondLevelMaturity = defaultCSV
}
// Keep track of the second level tx maturity.
carolSecondLevelCSV := secondLevelMaturity
// When Bob notices Carol's second level transaction in the block, he
// will extract the preimage and broadcast a second level tx to claim
// the HTLC in his (already closed) channel with Alice.
bobSecondLvlTx, err := waitForTxInMempool(
net.Miner.Node, minerMempoolTimeout,
)
require.NoError(t.t, err)
// It should spend from the commitment in the channel with Alice.
tx, err := net.Miner.Node.GetRawTransaction(bobSecondLvlTx)
require.NoError(t.t, err)
require.Equal(
t.t, *bobForceClose, tx.MsgTx().TxIn[0].PreviousOutPoint.Hash,
)
// At this point, Bob should have broadcast his second layer success
// transaction, and should have sent it to the nursery for incubation.
ctxt, _ = context.WithTimeout(ctxb, defaultTimeout)
err = waitForNumChannelPendingForceClose(
ctxt, bob, 1, func(c *lnrpcForceCloseChannel) error {
if c.Channel.LocalBalance != 0 {
return nil
}
if len(c.PendingHtlcs) != 1 {
return fmt.Errorf("bob should have pending " +
"htlc but doesn't")
}
if c.PendingHtlcs[0].Stage != 1 {
return fmt.Errorf("bob's htlc should have "+
"advanced to the first stage but was "+
"stage: %v", c.PendingHtlcs[0].Stage)
}
return nil
},
)
require.NoError(t.t, err)
// We'll now mine a block which should confirm Bob's second layer
// transaction.
block = mineBlocks(t, net, 1, 1)[0]
require.Len(t.t, block.Transactions, 2)
assertTxInBlock(t, block, bobSecondLvlTx)
// Keep track of Bob's second level maturity, and decrement our track
// of Carol's.
bobSecondLevelCSV := secondLevelMaturity
carolSecondLevelCSV--
// Now that the preimage from Bob has hit the chain, restart Alice to
// ensure she'll pick it up.
err = restartAlice()
require.NoError(t.t, err)
// If we then mine 3 additional blocks, Carol's second level tx should
// mature, and she can pull the funds from it with a sweep tx.
_, err = net.Miner.Node.Generate(carolSecondLevelCSV)
require.NoError(t.t, err)
bobSecondLevelCSV -= carolSecondLevelCSV
carolSweep, err := waitForTxInMempool(net.Miner.Node, minerMempoolTimeout)
require.NoError(t.t, err)
// Mining one additional block, Bob's second level tx is mature, and he
// can sweep the output.
block = mineBlocks(t, net, bobSecondLevelCSV, 1)[0]
assertTxInBlock(t, block, carolSweep)
bobSweep, err := waitForTxInMempool(net.Miner.Node, minerMempoolTimeout)
require.NoError(t.t, err)
// Make sure it spends from the second level tx.
tx, err = net.Miner.Node.GetRawTransaction(bobSweep)
require.NoError(t.t, err)
require.Equal(
t.t, *bobSecondLvlTx, tx.MsgTx().TxIn[0].PreviousOutPoint.Hash,
)
// When we mine one additional block, that will confirm Bob's sweep.
// Now Bob should have no pending channels anymore, as this just
// resolved it by the confirmation of the sweep transaction.
block = mineBlocks(t, net, 1, 1)[0]
assertTxInBlock(t, block, bobSweep)
ctxt, _ = context.WithTimeout(ctxb, defaultTimeout)
err = waitForNumChannelPendingForceClose(ctxt, bob, 0, nil)
require.NoError(t.t, err)
assertNodeNumChannels(t, bob, 0)
// Also Carol should have no channels left (open nor pending).
err = waitForNumChannelPendingForceClose(ctxt, carol, 0, nil)
require.NoError(t.t, err)
assertNodeNumChannels(t, carol, 0)
// 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)
}