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

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package itest
import (
"context"
"time"
"github.com/btcsuite/btcd/chaincfg/chainhash"
"github.com/btcsuite/btcd/wire"
"github.com/btcsuite/btcutil"
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"github.com/lightningnetwork/lnd/lncfg"
"github.com/lightningnetwork/lnd/lnrpc"
"github.com/lightningnetwork/lnd/lnrpc/routerrpc"
"github.com/lightningnetwork/lnd/lntest"
"github.com/lightningnetwork/lnd/lntest/wait"
"github.com/stretchr/testify/require"
)
// testMultiHopHtlcLocalTimeout tests that in a multi-hop HTLC scenario, if the
// outgoing HTLC is about to time out, then we'll go to chain in order to claim
// it using the HTLC timeout transaction. Any dust HTLC's should be immediately
// canceled backwards. Once the timeout has been reached, then we should sweep
// it on-chain, and cancel the HTLC backwards.
func testMultiHopHtlcLocalTimeout(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, true, c,
)
// Clean up carol's node when the test finishes.
defer shutdownAndAssert(net, t, carol)
time.Sleep(time.Second * 1)
// Now that our channels are set up, we'll send two HTLC's from Alice
// to Carol. The first HTLC will be universally considered "dust",
// while the second will be a proper fully valued HTLC.
const (
dustHtlcAmt = btcutil.Amount(100)
htlcAmt = btcutil.Amount(300_000)
finalCltvDelta = 40
)
ctx, cancel := context.WithCancel(ctxb)
defer cancel()
// We'll create two random payment hashes unknown to carol, then send
// each of them by manually specifying the HTLC details.
carolPubKey := carol.PubKey[:]
dustPayHash := makeFakePayHash(t)
payHash := makeFakePayHash(t)
_, err := alice.RouterClient.SendPaymentV2(
ctx, &routerrpc.SendPaymentRequest{
Dest: carolPubKey,
Amt: int64(dustHtlcAmt),
PaymentHash: dustPayHash,
FinalCltvDelta: finalCltvDelta,
TimeoutSeconds: 60,
FeeLimitMsat: noFeeLimitMsat,
},
)
require.NoError(t.t, err)
_, err = alice.RouterClient.SendPaymentV2(
ctx, &routerrpc.SendPaymentRequest{
Dest: carolPubKey,
Amt: int64(htlcAmt),
PaymentHash: payHash,
FinalCltvDelta: finalCltvDelta,
TimeoutSeconds: 60,
FeeLimitMsat: noFeeLimitMsat,
},
)
require.NoError(t.t, err)
// Verify that all nodes in the path now have two HTLC's with the
// proper parameters.
nodes := []*lntest.HarnessNode{alice, bob, carol}
err = wait.NoError(func() error {
return assertActiveHtlcs(nodes, dustPayHash, payHash)
}, defaultTimeout)
require.NoError(t.t, err)
// Increase the fee estimate so that the following force close tx will
// be cpfp'ed.
net.SetFeeEstimate(30000)
// We'll now mine enough blocks to trigger Bob's broadcast of his
// 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(
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uint32(finalCltvDelta - lncfg.DefaultOutgoingBroadcastDelta),
)
_, err = net.Miner.Node.Generate(numBlocks)
require.NoError(t.t, err)
// Bob's force close transaction should now be found in the mempool. If
// there are anchors, we also expect Bob's anchor sweep.
expectedTxes := 1
if c == commitTypeAnchors {
expectedTxes = 2
}
bobFundingTxid, err := lnrpc.GetChanPointFundingTxid(bobChanPoint)
require.NoError(t.t, err)
_, err = waitForNTxsInMempool(
net.Miner.Node, expectedTxes, minerMempoolTimeout,
)
require.NoError(t.t, err)
closeTx := getSpendingTxInMempool(
t, net.Miner.Node, minerMempoolTimeout, wire.OutPoint{
Hash: *bobFundingTxid,
Index: bobChanPoint.OutputIndex,
},
)
closeTxid := closeTx.TxHash()
// Mine a block to confirm the closing transaction.
mineBlocks(t, net, 1, expectedTxes)
// At this point, Bob should have canceled backwards the dust HTLC
// that we sent earlier. This means Alice should now only have a single
// HTLC on her channel.
nodes = []*lntest.HarnessNode{alice}
err = wait.NoError(func() error {
return assertActiveHtlcs(nodes, payHash)
}, defaultTimeout)
require.NoError(t.t, err)
// With the closing transaction confirmed, we should expect Bob's HTLC
// timeout transaction to be broadcast due to the expiry being reached.
// If there are anchors, we also expect Carol's anchor sweep now.
txes, err := getNTxsFromMempool(
net.Miner.Node, expectedTxes, minerMempoolTimeout,
)
require.NoError(t.t, err)
// Lookup the timeout transaction that is expected to spend from the
// closing tx. We distinguish it from a possibly anchor sweep by value.
var htlcTimeout *chainhash.Hash
for _, tx := range txes {
prevOp := tx.TxIn[0].PreviousOutPoint
require.Equal(t.t, closeTxid, prevOp.Hash)
// Assume that the timeout tx doesn't spend an output of exactly
// the size of the anchor.
if closeTx.TxOut[prevOp.Index].Value != anchorSize {
hash := tx.TxHash()
htlcTimeout = &hash
}
}
require.NotNil(t.t, htlcTimeout)
// We'll mine the remaining blocks in order to generate the sweep
// transaction of Bob's commitment output. The commitment was just
// mined at the current tip and the sweep will be broadcast so it can
// be mined at the tip+defaultCSV'th block, so mine one less to be able
// to make mempool assertions.
mineBlocks(t, net, defaultCSV-1, expectedTxes)
// Check that the sweep spends from the mined commitment.
txes, err = getNTxsFromMempool(net.Miner.Node, 1, minerMempoolTimeout)
require.NoError(t.t, err)
assertAllTxesSpendFrom(t, txes, closeTxid)
// Bob's pending channel report should show that he has a commitment
// output awaiting sweeping, and also that there's an outgoing HTLC
// output pending.
pendingChansRequest := &lnrpc.PendingChannelsRequest{}
ctxt, _ := context.WithTimeout(ctxb, defaultTimeout)
pendingChanResp, err := bob.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)
require.NotZero(t.t, len(forceCloseChan.PendingHtlcs))
// Mine a block to confirm Bob's commit sweep tx and assert it was in
// fact mined.
block := mineBlocks(t, net, 1, 1)[0]
commitSweepTxid := txes[0].TxHash()
assertTxInBlock(t, block, &commitSweepTxid)
// Mine an additional block to prompt Bob to broadcast their second
// layer sweep due to the CSV on the HTLC timeout output.
mineBlocks(t, net, 1, 0)
assertSpendingTxInMempool(
t, net.Miner.Node, minerMempoolTimeout, wire.OutPoint{
Hash: *htlcTimeout,
Index: 0,
},
)
// The block should have confirmed Bob's HTLC timeout transaction.
// Therefore, at this point, there should be no active HTLC's on the
// commitment transaction from Alice -> Bob.
nodes = []*lntest.HarnessNode{alice}
err = wait.NoError(func() error {
return assertNumActiveHtlcs(nodes, 0)
}, defaultTimeout)
require.NoError(t.t, err)
// At this point, Bob should show that the pending HTLC has advanced to
// the second stage and is to be swept.
ctxt, _ = context.WithTimeout(ctxb, defaultTimeout)
pendingChanResp, err = bob.PendingChannels(ctxt, pendingChansRequest)
require.NoError(t.t, err)
forceCloseChan = pendingChanResp.PendingForceClosingChannels[0]
require.Equal(t.t, uint32(2), forceCloseChan.PendingHtlcs[0].Stage)
// Next, we'll mine a final block that should confirm the second-layer
// sweeping transaction.
_, err = net.Miner.Node.Generate(1)
require.NoError(t.t, err)
// Once this transaction has been confirmed, Bob should detect that he
// no longer has any pending channels.
ctxt, _ = context.WithTimeout(ctxb, defaultTimeout)
err = waitForNumChannelPendingForceClose(ctxt, bob, 0, nil)
require.NoError(t.t, err)
// Coop close channel, expect no anchors.
ctxt, _ = context.WithTimeout(ctxb, channelCloseTimeout)
closeChannelAndAssertType(
ctxt, t, net, alice, aliceChanPoint, false, false,
)
}