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

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// +build rpctest
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package itest
import (
"context"
"fmt"
"time"
"github.com/btcsuite/btcd/wire"
"github.com/davecgh/go-spew/spew"
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"github.com/lightningnetwork/lnd"
"github.com/lightningnetwork/lnd/lnrpc"
"github.com/lightningnetwork/lnd/lnrpc/invoicesrpc"
"github.com/lightningnetwork/lnd/lntest"
"github.com/lightningnetwork/lnd/lntypes"
)
// testMultiHopHtlcRemoteChainClaim tests that in the multi-hop HTLC scenario,
// if the remote party goes to chain while we have an incoming HTLC, then when
// we found out the preimage via the witness beacon, we properly settle the
// HTLC on-chain in order to ensure that we don't lose any funds.
func testMultiHopHtlcRemoteChainClaim(net *lntest.NetworkHarness, t *harnessTest) {
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, false,
)
// 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, 5}
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)
if err != nil {
t.Fatalf("unable to add invoice: %v", 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()
alicePayStream, err := net.Alice.SendPayment(ctx)
if err != nil {
t.Fatalf("unable to create payment stream for alice: %v", err)
}
err = alicePayStream.Send(&lnrpc.SendRequest{
PaymentRequest: carolInvoice.PaymentRequest,
})
if err != nil {
t.Fatalf("unable to send payment: %v", err)
}
// At this point, all 3 nodes should now have an active channel with
// the created HTLC pending on all of them.
var predErr error
nodes := []*lntest.HarnessNode{net.Alice, net.Bob, carol}
err = lntest.WaitPredicate(func() bool {
predErr = assertActiveHtlcs(nodes, payHash[:])
if predErr != nil {
return false
}
return true
}, time.Second*15)
if err != nil {
t.Fatalf("htlc mismatch: %v", predErr)
}
// 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)
// Next, Alice decides that she wants to exit the channel, so she'll
// immediately force close the channel by broadcast her commitment
// transaction.
ctxt, _ = context.WithTimeout(ctxb, channelCloseTimeout)
aliceForceClose := closeChannelAndAssert(ctxt, t, net, net.Alice,
aliceChanPoint, true)
// Wait for the channel to be marked pending force close.
ctxt, _ = context.WithTimeout(ctxb, defaultTimeout)
err = waitForChannelPendingForceClose(ctxt, net.Alice, aliceChanPoint)
if err != nil {
t.Fatalf("channel not pending force close: %v", err)
}
// Mine enough blocks for Alice to sweep her funds from the force
// closed channel.
_, err = net.Miner.Node.Generate(defaultCSV)
if err != nil {
t.Fatalf("unable to generate blocks: %v", err)
}
// Alice should now sweep her funds.
_, err = waitForTxInMempool(net.Miner.Node, minerMempoolTimeout)
if err != nil {
t.Fatalf("unable to find sweeping tx in mempool: %v", err)
}
// Suspend bob, so Carol is forced to go on chain.
restartBob, err := net.SuspendNode(net.Bob)
if err != nil {
t.Fatalf("unable to suspend bob: %v", 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[:],
})
if err != nil {
t.Fatalf("settle invoice: %v", 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-
lnd.DefaultIncomingBroadcastDelta) - defaultCSV)
if _, err := net.Miner.Node.Generate(numBlocks); err != nil {
t.Fatalf("unable to generate blocks")
}
// Carol's commitment transaction should now be in the mempool.
txids, err := waitForNTxsInMempool(net.Miner.Node, 1, minerMempoolTimeout)
if err != nil {
t.Fatalf("transactions not found in mempool: %v", err)
}
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bobFundingTxid, err := lnd.GetChanPointFundingTxid(bobChanPoint)
if err != nil {
t.Fatalf("unable to get txid: %v", err)
}
carolFundingPoint := wire.OutPoint{
Hash: *bobFundingTxid,
Index: bobChanPoint.OutputIndex,
}
// The transaction should be spending from the funding transaction
commitHash := txids[0]
tx1, err := net.Miner.Node.GetRawTransaction(commitHash)
if err != nil {
t.Fatalf("unable to get txn: %v", err)
}
if tx1.MsgTx().TxIn[0].PreviousOutPoint != carolFundingPoint {
t.Fatalf("commit transaction not spending fundingtx: %v",
spew.Sdump(tx1))
}
// Mine a block, which should contain the commitment.
block := mineBlocks(t, net, 1, 1)[0]
if len(block.Transactions) != 2 {
t.Fatalf("expected 2 transactions in block, got %v",
len(block.Transactions))
}
assertTxInBlock(t, block, commitHash)
// Restart bob again.
if err := restartBob(); err != nil {
t.Fatalf("unable to restart bob: %v", 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.
commitSpends, err := waitForNTxsInMempool(net.Miner.Node, 2,
minerMempoolTimeout)
if err != nil {
t.Fatalf("transactions not found in mempool: %v", err)
}
// Both Carol's second level transaction and Bob's sweep should be
// spending from the commitment transaction.
for _, txid := range commitSpends {
tx, err := net.Miner.Node.GetRawTransaction(txid)
if err != nil {
t.Fatalf("unable to get txn: %v", err)
}
if tx.MsgTx().TxIn[0].PreviousOutPoint.Hash != *commitHash {
t.Fatalf("tx did not spend from commitment tx")
}
}
// Mine a block to confirm the two transactions (+ coinbase).
block = mineBlocks(t, net, 1, 2)[0]
if len(block.Transactions) != 3 {
t.Fatalf("expected 3 transactions in block, got %v",
len(block.Transactions))
}
for _, txid := range commitSpends {
assertTxInBlock(t, block, txid)
}
// Keep track of the second level tx maturity.
carolSecondLevelCSV := uint32(defaultCSV)
// When Bob notices Carol's second level transaction in the block, he
// will extract the preimage and broadcast a sweep tx to directly claim
// the HTLC in his (already closed) channel with Alice.
bobHtlcSweep, err := waitForTxInMempool(net.Miner.Node,
minerMempoolTimeout)
if err != nil {
t.Fatalf("transactions not found in mempool: %v", err)
}
// It should spend from the commitment in the channel with Alice.
tx, err := net.Miner.Node.GetRawTransaction(bobHtlcSweep)
if err != nil {
t.Fatalf("unable to get txn: %v", err)
}
if tx.MsgTx().TxIn[0].PreviousOutPoint.Hash != *aliceForceClose {
t.Fatalf("tx did not spend from alice's force close tx")
}
// We'll now mine a block which should confirm Bob's HTLC sweep
// transaction.
block = mineBlocks(t, net, 1, 1)[0]
if len(block.Transactions) != 2 {
t.Fatalf("expected 2 transactions in block, got %v",
len(block.Transactions))
}
assertTxInBlock(t, block, bobHtlcSweep)
carolSecondLevelCSV--
// Now that the sweeping transaction has been confirmed, Bob should now
// recognize that all contracts have been fully resolved, and show no
// pending close channels.
pendingChansRequest := &lnrpc.PendingChannelsRequest{}
err = lntest.WaitPredicate(func() bool {
ctxt, _ = context.WithTimeout(ctxb, defaultTimeout)
pendingChanResp, err := net.Bob.PendingChannels(
ctxt, pendingChansRequest,
)
if err != nil {
predErr = fmt.Errorf("unable to query for pending "+
"channels: %v", err)
return false
}
if len(pendingChanResp.PendingForceClosingChannels) != 0 {
predErr = fmt.Errorf("bob still has pending channels "+
"but shouldn't: %v", spew.Sdump(pendingChanResp))
return false
}
return true
}, time.Second*15)
if err != nil {
t.Fatalf(predErr.Error())
}
// If we then mine 3 additional blocks, Carol's second level tx will
// mature, and she should pull the funds.
if _, err := net.Miner.Node.Generate(carolSecondLevelCSV); err != nil {
t.Fatalf("unable to generate block: %v", err)
}
carolSweep, err := waitForTxInMempool(net.Miner.Node, minerMempoolTimeout)
if err != nil {
t.Fatalf("unable to find Carol's sweeping transaction: %v", err)
}
// When Carol's sweep gets confirmed, she should have no more pending
// channels.
block = mineBlocks(t, net, 1, 1)[0]
assertTxInBlock(t, block, carolSweep)
pendingChansRequest = &lnrpc.PendingChannelsRequest{}
err = lntest.WaitPredicate(func() bool {
ctxt, _ = context.WithTimeout(ctxb, defaultTimeout)
pendingChanResp, err := carol.PendingChannels(
ctxt, pendingChansRequest,
)
if err != nil {
predErr = fmt.Errorf("unable to query for pending "+
"channels: %v", err)
return false
}
if len(pendingChanResp.PendingForceClosingChannels) != 0 {
predErr = fmt.Errorf("carol still has pending channels "+
"but shouldn't: %v", spew.Sdump(pendingChanResp))
return false
}
return true
}, time.Second*15)
if err != nil {
t.Fatalf(predErr.Error())
}
// The invoice should show as settled for Carol, indicating that it was
// swept on-chain.
invoicesReq := &lnrpc.ListInvoiceRequest{}
invoicesResp, err := carol.ListInvoices(ctxb, invoicesReq)
if err != nil {
t.Fatalf("unable to retrieve invoices: %v", err)
}
if len(invoicesResp.Invoices) != 1 {
t.Fatalf("expected 1 invoice, got %d", len(invoicesResp.Invoices))
}
invoice := invoicesResp.Invoices[0]
if invoice.State != lnrpc.Invoice_SETTLED {
t.Fatalf("expected invoice to be settled on chain")
}
if invoice.AmtPaidSat != invoiceAmt {
t.Fatalf("expected invoice to be settled with %d sat, got "+
"%d sat", invoiceAmt, invoice.AmtPaidSat)
}
}