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, Cancel: func() {}, }, 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) Started() bool { return true } 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( channeldb.SingleFunderTweaklessBit, ) 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 *RemoteUnilateralCloseInfo 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( channeldb.SingleFunderTweaklessBit, ) 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 *RemoteUnilateralCloseInfo 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 special 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 } func executeStateTransitions(t *testing.T, htlcAmount lnwire.MilliSatoshi, aliceChannel, bobChannel *lnwallet.LightningChannel, numUpdates uint8) error { for i := 0; i < int(numUpdates); i++ { addFakeHTLC( t, htlcAmount, uint64(i), aliceChannel, bobChannel, ) err := lnwallet.ForceStateTransition(aliceChannel, bobChannel) if err != nil { return err } } return nil } // 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( channeldb.SingleFunderBit, ) 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 err = executeStateTransitions( t, htlcAmt, aliceChannel, bobChannel, testCase.NumUpdates, ) 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 *RemoteUnilateralCloseInfo 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) } }) } } // TestChainWatcherLocalForceCloseDetect tests we're able to always detect our // commitment output based on only the outputs present on the transaction. func TestChainWatcherLocalForceCloseDetect(t *testing.T) { t.Parallel() // localForceCloseScenario is the primary test we'll use to execute our // table driven tests. We'll assert that for any number of state // updates, and if the commitment transaction has our output or not, // we're able to properly detect a local force close. localForceCloseScenario := func(t *testing.T, numUpdates uint8, remoteOutputOnly, localOutputOnly bool) bool { // First, we'll create two channels which already have // established a commitment contract between themselves. aliceChannel, bobChannel, cleanUp, err := lnwallet.CreateTestChannels( channeldb.SingleFunderBit, ) 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 execute a number of state transitions based on the // randomly selected number from testing/quick. We do this to // get more coverage of various state hint encodings beyond 0 // and 1. const htlcAmt = 1000 err = executeStateTransitions( t, htlcAmt, aliceChannel, bobChannel, numUpdates, ) 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() // Next, we'll obtain Alice's commitment transaction and // trigger a force close. This should cause her to detect a // local force close, and dispatch a local close event. aliceCommit := aliceChannel.State().LocalCommitment.CommitTx // Since this is Alice's commitment, her output is always first // since she's the one creating the HTLCs (lower balance). In // order to simulate the commitment only having the remote // party's output, we'll remove Alice's output. if remoteOutputOnly { aliceCommit.TxOut = aliceCommit.TxOut[1:] } if localOutputOnly { aliceCommit.TxOut = aliceCommit.TxOut[:1] } aliceTxHash := aliceCommit.TxHash() aliceSpend := &chainntnfs.SpendDetail{ SpenderTxHash: &aliceTxHash, SpendingTx: aliceCommit, } aliceNotifier.spendChan <- aliceSpend // We should get a local force close event from Alice as she // should be able to detect the close based on the commitment // outputs. select { case <-chanEvents.LocalUnilateralClosure: return true case <-time.After(time.Second * 5): t.Errorf("didn't get local for close for state #%v", numUpdates) return false } } // For our test cases, we'll ensure that we test having a remote output // present and absent with non or some number of updates in the channel. testCases := []struct { numUpdates uint8 remoteOutputOnly bool localOutputOnly bool }{ { numUpdates: 0, remoteOutputOnly: true, }, { numUpdates: 0, remoteOutputOnly: false, }, { numUpdates: 0, localOutputOnly: true, }, { numUpdates: 20, remoteOutputOnly: false, }, { numUpdates: 20, remoteOutputOnly: true, }, { numUpdates: 20, localOutputOnly: true, }, } for _, testCase := range testCases { testName := fmt.Sprintf( "num_updates=%v,remote_output=%v,local_output=%v", testCase.numUpdates, testCase.remoteOutputOnly, testCase.localOutputOnly, ) testCase := testCase t.Run(testName, func(t *testing.T) { t.Parallel() localForceCloseScenario( t, testCase.numUpdates, testCase.remoteOutputOnly, testCase.localOutputOnly, ) }) } }