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

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// +build rpctest
package itest
import (
"context"
"fmt"
"time"
"github.com/btcsuite/btcd/chaincfg/chainhash"
"github.com/btcsuite/btcd/wire"
"github.com/btcsuite/btcutil"
"github.com/davecgh/go-spew/spew"
"github.com/lightningnetwork/lnd"
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"github.com/lightningnetwork/lnd/lncfg"
"github.com/lightningnetwork/lnd/lnrpc"
"github.com/lightningnetwork/lnd/lntest"
"github.com/lightningnetwork/lnd/lntest/wait"
)
// 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(30000)
finalCltvDelta = 40
)
ctx, cancel := context.WithCancel(ctxb)
defer cancel()
alicePayStream, err := alice.SendPayment(ctx)
if err != nil {
t.Fatalf("unable to create payment stream for alice: %v", err)
}
// 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 = alicePayStream.Send(&lnrpc.SendRequest{
Dest: carolPubKey,
Amt: int64(dustHtlcAmt),
PaymentHash: dustPayHash,
FinalCltvDelta: finalCltvDelta,
})
if err != nil {
t.Fatalf("unable to send alice htlc: %v", err)
}
err = alicePayStream.Send(&lnrpc.SendRequest{
Dest: carolPubKey,
Amt: int64(htlcAmt),
PaymentHash: payHash,
FinalCltvDelta: finalCltvDelta,
})
if err != nil {
t.Fatalf("unable to send alice htlc: %v", err)
}
// Verify that all nodes in the path now have two HTLC's with the
// proper parameters.
var predErr error
nodes := []*lntest.HarnessNode{alice, bob, carol}
err = wait.Predicate(func() bool {
predErr = assertActiveHtlcs(nodes, dustPayHash, payHash)
if predErr != nil {
return false
}
return true
}, time.Second*15)
if err != nil {
t.Fatalf("htlc mismatch: %v", predErr)
}
// 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),
)
if _, err := net.Miner.Node.Generate(numBlocks); err != nil {
t.Fatalf("unable to generate blocks: %v", 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 := lnd.GetChanPointFundingTxid(bobChanPoint)
if err != nil {
t.Fatalf("unable to get txid: %v", err)
}
_, err = waitForNTxsInMempool(
net.Miner.Node, expectedTxes, minerMempoolTimeout,
)
if err != nil {
t.Fatalf("unable to find closing txid: %v", 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.Predicate(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)
}
// 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)
if err != nil {
t.Fatalf("unable to find bob's htlc timeout tx: %v", 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
if prevOp.Hash != closeTxid {
t.Fatalf("tx not spending from closing tx")
}
// 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
}
}
if htlcTimeout == nil {
t.Fatalf("htlc timeout tx not found in mempool")
}
// We'll mine the remaining blocks in order to generate the sweep
// transaction of Bob's commitment output.
mineBlocks(t, net, defaultCSV, expectedTxes)
// Check that the sweep spends from the mined commitment.
txes, err = getNTxsFromMempool(net.Miner.Node, 1, minerMempoolTimeout)
if err != nil {
t.Fatalf("sweep not found: %v", 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)
if err != nil {
t.Fatalf("unable to query for pending channels: %v", err)
}
if len(pendingChanResp.PendingForceClosingChannels) == 0 {
t.Fatalf("bob should have pending for close chan but doesn't")
}
forceCloseChan := pendingChanResp.PendingForceClosingChannels[0]
if forceCloseChan.LimboBalance == 0 {
t.Fatalf("bob should have nonzero limbo balance instead "+
"has: %v", forceCloseChan.LimboBalance)
}
if len(forceCloseChan.PendingHtlcs) == 0 {
t.Fatalf("bob should have pending htlc but doesn't")
}
// Now we'll mine an additional block, which should confirm Bob's commit
// sweep. This block should also prompt Bob to broadcast their second
// layer sweep due to the CSV on the HTLC timeout output.
mineBlocks(t, net, 1, 1)
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.Predicate(func() bool {
predErr = assertNumActiveHtlcs(nodes, 0)
if predErr != nil {
return false
}
return true
}, time.Second*15)
if err != nil {
t.Fatalf("alice's channel still has active htlc's: %v", predErr)
}
// 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)
if err != nil {
t.Fatalf("unable to query for pending channels: %v", err)
}
forceCloseChan = pendingChanResp.PendingForceClosingChannels[0]
if forceCloseChan.PendingHtlcs[0].Stage != 2 {
t.Fatalf("bob's htlc should have advanced to the second stage: %v", err)
}
// Next, we'll mine a final block that should confirm the second-layer
// sweeping transaction.
if _, err := net.Miner.Node.Generate(1); err != nil {
t.Fatalf("unable to generate blocks: %v", err)
}
// Once this transaction has been confirmed, Bob should detect that he
// no longer has any pending channels.
err = wait.Predicate(func() bool {
ctxt, _ = context.WithTimeout(ctxb, defaultTimeout)
pendingChanResp, err = 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())
}
// Coop close channel, expect no anchors.
ctxt, _ = context.WithTimeout(ctxb, channelCloseTimeout)
closeChannelAndAssertType(
ctxt, t, net, alice, aliceChanPoint, false,
false,
)
}