lnd.xprv/contractcourt/chain_watcher_test.go

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package contractcourt
import (
"bytes"
"crypto/sha256"
"fmt"
"testing"
"time"
"github.com/btcsuite/btcd/chaincfg/chainhash"
"github.com/btcsuite/btcd/wire"
"github.com/lightningnetwork/lnd/chainntnfs"
"github.com/lightningnetwork/lnd/channeldb"
"github.com/lightningnetwork/lnd/input"
"github.com/lightningnetwork/lnd/lnwallet"
"github.com/lightningnetwork/lnd/lnwire"
)
type mockNotifier struct {
spendChan chan *chainntnfs.SpendDetail
epochChan chan *chainntnfs.BlockEpoch
confChan chan *chainntnfs.TxConfirmation
}
func (m *mockNotifier) RegisterConfirmationsNtfn(txid *chainhash.Hash, _ []byte, numConfs,
heightHint uint32) (*chainntnfs.ConfirmationEvent, error) {
return &chainntnfs.ConfirmationEvent{
Confirmed: m.confChan,
}, nil
}
func (m *mockNotifier) RegisterBlockEpochNtfn(
bestBlock *chainntnfs.BlockEpoch) (*chainntnfs.BlockEpochEvent, error) {
return &chainntnfs.BlockEpochEvent{
Epochs: m.epochChan,
Cancel: func() {},
}, nil
}
func (m *mockNotifier) Start() error {
return nil
}
func (m *mockNotifier) Stop() error {
return nil
}
func (m *mockNotifier) RegisterSpendNtfn(outpoint *wire.OutPoint, _ []byte,
heightHint uint32) (*chainntnfs.SpendEvent, error) {
return &chainntnfs.SpendEvent{
Spend: m.spendChan,
Cancel: func() {},
}, nil
}
// TestChainWatcherRemoteUnilateralClose tests that the chain watcher is able
// to properly detect a normal unilateral close by the remote node using their
// lowest commitment.
func TestChainWatcherRemoteUnilateralClose(t *testing.T) {
t.Parallel()
// First, we'll create two channels which already have established a
// commitment contract between themselves.
aliceChannel, bobChannel, cleanUp, err := lnwallet.CreateTestChannels()
if err != nil {
t.Fatalf("unable to create test channels: %v", err)
}
defer cleanUp()
// With the channels created, we'll now create a chain watcher instance
// which will be watching for any closes of Alice's channel.
aliceNotifier := &mockNotifier{
spendChan: make(chan *chainntnfs.SpendDetail),
}
aliceChainWatcher, err := newChainWatcher(chainWatcherConfig{
chanState: aliceChannel.State(),
notifier: aliceNotifier,
signer: aliceChannel.Signer,
extractStateNumHint: lnwallet.GetStateNumHint,
})
if err != nil {
t.Fatalf("unable to create chain watcher: %v", err)
}
err = aliceChainWatcher.Start()
if err != nil {
t.Fatalf("unable to start chain watcher: %v", err)
}
defer aliceChainWatcher.Stop()
// We'll request a new channel event subscription from Alice's chain
// watcher.
chanEvents := aliceChainWatcher.SubscribeChannelEvents()
// If we simulate an immediate broadcast of the current commitment by
// Bob, then the chain watcher should detect this case.
bobCommit := bobChannel.State().LocalCommitment.CommitTx
bobTxHash := bobCommit.TxHash()
bobSpend := &chainntnfs.SpendDetail{
SpenderTxHash: &bobTxHash,
SpendingTx: bobCommit,
}
aliceNotifier.spendChan <- bobSpend
// We should get a new spend event over the remote unilateral close
// event channel.
var uniClose *lnwallet.UnilateralCloseSummary
select {
case uniClose = <-chanEvents.RemoteUnilateralClosure:
case <-time.After(time.Second * 15):
t.Fatalf("didn't receive unilateral close event")
}
// The unilateral close should have properly located Alice's output in
// the commitment transaction.
if uniClose.CommitResolution == nil {
t.Fatalf("unable to find alice's commit resolution")
}
}
func addFakeHTLC(t *testing.T, htlcAmount lnwire.MilliSatoshi, id uint64,
aliceChannel, bobChannel *lnwallet.LightningChannel) {
preimage := bytes.Repeat([]byte{byte(id)}, 32)
paymentHash := sha256.Sum256(preimage)
var returnPreimage [32]byte
copy(returnPreimage[:], preimage)
htlc := &lnwire.UpdateAddHTLC{
ID: uint64(id),
PaymentHash: paymentHash,
Amount: htlcAmount,
Expiry: uint32(5),
}
if _, err := aliceChannel.AddHTLC(htlc, nil); err != nil {
t.Fatalf("alice unable to add htlc: %v", err)
}
if _, err := bobChannel.ReceiveHTLC(htlc); err != nil {
t.Fatalf("bob unable to recv add htlc: %v", err)
}
}
// TestChainWatcherRemoteUnilateralClosePendingCommit tests that the chain
// watcher is able to properly detect a unilateral close wherein the remote
// node broadcasts their newly received commitment, without first revoking the
// old one.
func TestChainWatcherRemoteUnilateralClosePendingCommit(t *testing.T) {
t.Parallel()
// First, we'll create two channels which already have established a
// commitment contract between themselves.
aliceChannel, bobChannel, cleanUp, err := lnwallet.CreateTestChannels()
if err != nil {
t.Fatalf("unable to create test channels: %v", err)
}
defer cleanUp()
// With the channels created, we'll now create a chain watcher instance
// which will be watching for any closes of Alice's channel.
aliceNotifier := &mockNotifier{
spendChan: make(chan *chainntnfs.SpendDetail),
}
aliceChainWatcher, err := newChainWatcher(chainWatcherConfig{
chanState: aliceChannel.State(),
notifier: aliceNotifier,
signer: aliceChannel.Signer,
extractStateNumHint: lnwallet.GetStateNumHint,
})
if err != nil {
t.Fatalf("unable to create chain watcher: %v", err)
}
if err := aliceChainWatcher.Start(); err != nil {
t.Fatalf("unable to start chain watcher: %v", err)
}
defer aliceChainWatcher.Stop()
// We'll request a new channel event subscription from Alice's chain
// watcher.
chanEvents := aliceChainWatcher.SubscribeChannelEvents()
// Next, we'll create a fake HTLC just so we can advance Alice's
// channel state to a new pending commitment on her remote commit chain
// for Bob.
htlcAmount := lnwire.NewMSatFromSatoshis(20000)
addFakeHTLC(t, htlcAmount, 0, aliceChannel, bobChannel)
// With the HTLC added, we'll now manually initiate a state transition
// from Alice to Bob.
_, _, err = aliceChannel.SignNextCommitment()
if err != nil {
t.Fatal(err)
}
// At this point, we'll now Bob broadcasting this new pending unrevoked
// commitment.
bobPendingCommit, err := aliceChannel.State().RemoteCommitChainTip()
if err != nil {
t.Fatal(err)
}
// We'll craft a fake spend notification with Bob's actual commitment.
// The chain watcher should be able to detect that this is a pending
// commit broadcast based on the state hints in the commitment.
bobCommit := bobPendingCommit.Commitment.CommitTx
bobTxHash := bobCommit.TxHash()
bobSpend := &chainntnfs.SpendDetail{
SpenderTxHash: &bobTxHash,
SpendingTx: bobCommit,
}
aliceNotifier.spendChan <- bobSpend
// We should get a new spend event over the remote unilateral close
// event channel.
var uniClose *lnwallet.UnilateralCloseSummary
select {
case uniClose = <-chanEvents.RemoteUnilateralClosure:
case <-time.After(time.Second * 15):
t.Fatalf("didn't receive unilateral close event")
}
// The unilateral close should have properly located Alice's output in
// the commitment transaction.
if uniClose.CommitResolution == nil {
t.Fatalf("unable to find alice's commit resolution")
}
}
// dlpTestCase is a speical struct that we'll use to generate randomized test
// cases for the main TestChainWatcherDataLossProtect test. This struct has a
// special Generate method that will generate a random state number, and a
// broadcast state number which is greater than that state number.
type dlpTestCase struct {
BroadcastStateNum uint8
NumUpdates uint8
}
// TestChainWatcherDataLossProtect tests that if we've lost data (and are
// behind the remote node), then we'll properly detect this case and dispatch a
// remote force close using the obtained data loss commitment point.
func TestChainWatcherDataLossProtect(t *testing.T) {
t.Parallel()
// dlpScenario is our primary quick check testing function for this
// test as whole. It ensures that if the remote party broadcasts a
// commitment that is beyond our best known commitment for them, and
// they don't have a pending commitment (one we sent but which hasn't
// been revoked), then we'll properly detect this case, and execute the
// DLP protocol on our end.
//
// broadcastStateNum is the number that we'll trick Alice into thinking
// was broadcast, while numUpdates is the actual number of updates
// we'll execute. Both of these will be random 8-bit values generated
// by testing/quick.
dlpScenario := func(t *testing.T, testCase dlpTestCase) bool {
// First, we'll create two channels which already have
// established a commitment contract between themselves.
aliceChannel, bobChannel, cleanUp, err := lnwallet.CreateTestChannels()
if err != nil {
t.Fatalf("unable to create test channels: %v", err)
}
defer cleanUp()
// With the channels created, we'll now create a chain watcher
// instance which will be watching for any closes of Alice's
// channel.
aliceNotifier := &mockNotifier{
spendChan: make(chan *chainntnfs.SpendDetail),
}
aliceChainWatcher, err := newChainWatcher(chainWatcherConfig{
chanState: aliceChannel.State(),
notifier: aliceNotifier,
signer: aliceChannel.Signer,
extractStateNumHint: func(*wire.MsgTx,
[lnwallet.StateHintSize]byte) uint64 {
// We'll return the "fake" broadcast commitment
// number so we can simulate broadcast of an
// arbitrary state.
return uint64(testCase.BroadcastStateNum)
},
})
if err != nil {
t.Fatalf("unable to create chain watcher: %v", err)
}
if err := aliceChainWatcher.Start(); err != nil {
t.Fatalf("unable to start chain watcher: %v", err)
}
defer aliceChainWatcher.Stop()
// Based on the number of random updates for this state, make a
// new HTLC to add to the commitment, and then lock in a state
// transition.
const htlcAmt = 1000
for i := 0; i < int(testCase.NumUpdates); i++ {
addFakeHTLC(
t, 1000, uint64(i), aliceChannel, bobChannel,
)
err := lnwallet.ForceStateTransition(
aliceChannel, bobChannel,
)
if err != nil {
t.Errorf("unable to trigger state "+
"transition: %v", err)
return false
}
}
// We'll request a new channel event subscription from Alice's
// chain watcher so we can be notified of our fake close below.
chanEvents := aliceChainWatcher.SubscribeChannelEvents()
// Otherwise, we'll feed in this new state number as a response
// to the query, and insert the expected DLP commit point.
dlpPoint := aliceChannel.State().RemoteCurrentRevocation
err = aliceChannel.State().MarkDataLoss(dlpPoint)
if err != nil {
t.Errorf("unable to insert dlp point: %v", err)
return false
}
// Now we'll trigger the channel close event to trigger the
// scenario.
bobCommit := bobChannel.State().LocalCommitment.CommitTx
bobTxHash := bobCommit.TxHash()
bobSpend := &chainntnfs.SpendDetail{
SpenderTxHash: &bobTxHash,
SpendingTx: bobCommit,
}
aliceNotifier.spendChan <- bobSpend
// We should get a new uni close resolution that indicates we
// processed the DLP scenario.
var uniClose *lnwallet.UnilateralCloseSummary
select {
case uniClose = <-chanEvents.RemoteUnilateralClosure:
// If we processed this as a DLP case, then the remote
// party's commitment should be blank, as we don't have
// this up to date state.
blankCommit := channeldb.ChannelCommitment{}
if uniClose.RemoteCommit.FeePerKw != blankCommit.FeePerKw {
t.Errorf("DLP path not executed")
return false
}
// The resolution should have also read the DLP point
// we stored above, and used that to derive their sweep
// key for this output.
sweepTweak := input.SingleTweakBytes(
dlpPoint,
aliceChannel.State().LocalChanCfg.PaymentBasePoint.PubKey,
)
commitResolution := uniClose.CommitResolution
resolutionTweak := commitResolution.SelfOutputSignDesc.SingleTweak
if !bytes.Equal(sweepTweak, resolutionTweak) {
t.Errorf("sweep key mismatch: expected %x got %x",
sweepTweak, resolutionTweak)
return false
}
return true
case <-time.After(time.Second * 5):
t.Errorf("didn't receive unilateral close event")
return false
}
}
testCases := []dlpTestCase{
// For our first scenario, we'll ensure that if we're on state 1,
// and the remote party broadcasts state 2 and we don't have a
// pending commit for them, then we'll properly detect this as a
// DLP scenario.
{
BroadcastStateNum: 2,
NumUpdates: 1,
},
// We've completed a single update, but the remote party broadcasts
// a state that's 5 states byeond our best known state. We've lost
// data, but only partially, so we should enter a DLP secnario.
{
BroadcastStateNum: 6,
NumUpdates: 1,
},
// Similar to the case above, but we've done more than one
// update.
{
BroadcastStateNum: 6,
NumUpdates: 3,
},
// We've done zero updates, but our channel peer broadcasts a
// state beyond our knowledge.
{
BroadcastStateNum: 10,
NumUpdates: 0,
},
}
for _, testCase := range testCases {
testName := fmt.Sprintf("num_updates=%v,broadcast_state_num=%v",
testCase.NumUpdates, testCase.BroadcastStateNum)
testCase := testCase
t.Run(testName, func(t *testing.T) {
t.Parallel()
if !dlpScenario(t, testCase) {
t.Fatalf("test %v failed", testName)
}
})
}
}