multi: add bitcoind drivers and tests

chainntnfs/bitcoindnotify/bitcoind.go

@@ -0,0 +1,679 @@
+package bitcoindnotify
+
+import (
+	"errors"
+	"fmt"
+	"sync"
+	"sync/atomic"
+	"time"
+
+	"github.com/lightningnetwork/lnd/chainntnfs"
+	"github.com/roasbeef/btcd/btcjson"
+	"github.com/roasbeef/btcd/chaincfg"
+	"github.com/roasbeef/btcd/chaincfg/chainhash"
+	"github.com/roasbeef/btcd/rpcclient"
+	"github.com/roasbeef/btcd/wire"
+	"github.com/roasbeef/btcutil"
+	"github.com/roasbeef/btcwallet/chain"
+)
+
+const (
+
+	// notifierType uniquely identifies this concrete implementation of the
+	// ChainNotifier interface.
+	notifierType = "bitcoind"
+
+	// reorgSafetyLimit is assumed maximum depth of a chain reorganization.
+	// After this many confirmation, transaction confirmation info will be
+	// pruned.
+	reorgSafetyLimit = 100
+)
+
+var (
+	// ErrChainNotifierShuttingDown is used when we are trying to
+	// measure a spend notification when notifier is already stopped.
+	ErrChainNotifierShuttingDown = errors.New("chainntnfs: system interrupt " +
+		"while attempting to register for spend notification.")
+)
+
+// chainUpdate encapsulates an update to the current main chain. This struct is
+// used as an element within an unbounded queue in order to avoid blocking the
+// main rpc dispatch rule.
+type chainUpdate struct {
+	blockHash   *chainhash.Hash
+	blockHeight int32
+}
+
+// txUpdate encapsulates a transaction related notification sent from bitcoind
+// to the registered RPC client. This struct is used as an element within an
+// unbounded queue in order to avoid blocking the main rpc dispatch rule.
+type txUpdate struct {
+	tx      *btcutil.Tx
+	details *btcjson.BlockDetails
+}
+
+// TODO(roasbeef): generalize struct below:
+//  * move chans to config, allow outside callers to handle send conditions
+
+// BitcoindNotifier implements the ChainNotifier interface using a bitcoind
+// chain client. Multiple concurrent clients are supported. All notifications
+// are achieved via non-blocking sends on client channels.
+type BitcoindNotifier struct {
+	spendClientCounter uint64 // To be used atomically.
+	epochClientCounter uint64 // To be used atomically.
+
+	started int32 // To be used atomically.
+	stopped int32 // To be used atomically.
+
+	heightMtx  sync.RWMutex
+	bestHeight int32
+
+	chainConn *chain.BitcoindClient
+
+	notificationCancels  chan interface{}
+	notificationRegistry chan interface{}
+
+	spendNotifications map[wire.OutPoint]map[uint64]*spendNotification
+
+	txConfNotifier *chainntnfs.TxConfNotifier
+
+	blockEpochClients map[uint64]*blockEpochRegistration
+
+	wg   sync.WaitGroup
+	quit chan struct{}
+}
+
+// Ensure BitcoindNotifier implements the ChainNotifier interface at compile
+// time.
+var _ chainntnfs.ChainNotifier = (*BitcoindNotifier)(nil)
+
+// New returns a new BitcoindNotifier instance. This function assumes the
+// bitcoind node  detailed in the passed configuration is already running, and
+// willing to accept RPC requests and new zmq clients.
+func New(config *rpcclient.ConnConfig, zmqConnect string,
+	params chaincfg.Params) (*BitcoindNotifier, error) {
+	notifier := &BitcoindNotifier{
+		notificationCancels:  make(chan interface{}),
+		notificationRegistry: make(chan interface{}),
+
+		blockEpochClients: make(map[uint64]*blockEpochRegistration),
+
+		spendNotifications: make(map[wire.OutPoint]map[uint64]*spendNotification),
+
+		quit: make(chan struct{}),
+	}
+
+	// Disable connecting to bitcoind within the rpcclient.New method. We
+	// defer establishing the connection to our .Start() method.
+	config.DisableConnectOnNew = true
+	config.DisableAutoReconnect = false
+	chainConn, err := chain.NewBitcoindClient(&params, config.Host,
+		config.User, config.Pass, zmqConnect, 100*time.Millisecond)
+	if err != nil {
+		return nil, err
+	}
+	notifier.chainConn = chainConn
+
+	return notifier, nil
+}
+
+// Start connects to the running bitcoind node over websockets, registers for
+// block notifications, and finally launches all related helper goroutines.
+func (b *BitcoindNotifier) Start() error {
+	// Already started?
+	if atomic.AddInt32(&b.started, 1) != 1 {
+		return nil
+	}
+
+	// Connect to bitcoind, and register for notifications on connected,
+	// and disconnected blocks.
+	if err := b.chainConn.Start(); err != nil {
+		return err
+	}
+	if err := b.chainConn.NotifyBlocks(); err != nil {
+		return err
+	}
+
+	_, currentHeight, err := b.chainConn.GetBestBlock()
+	if err != nil {
+		return err
+	}
+
+	b.heightMtx.Lock()
+	b.bestHeight = currentHeight
+	b.heightMtx.Unlock()
+
+	b.txConfNotifier = chainntnfs.NewTxConfNotifier(
+		uint32(currentHeight), reorgSafetyLimit)
+
+	b.wg.Add(1)
+	go b.notificationDispatcher()
+
+	return nil
+}
+
+// Stop shutsdown the BitcoindNotifier.
+func (b *BitcoindNotifier) Stop() error {
+	// Already shutting down?
+	if atomic.AddInt32(&b.stopped, 1) != 1 {
+		return nil
+	}
+
+	// Shutdown the rpc client, this gracefully disconnects from bitcoind,
+	// and cleans up all related resources.
+	b.chainConn.Stop()
+
+	close(b.quit)
+	b.wg.Wait()
+
+	// Notify all pending clients of our shutdown by closing the related
+	// notification channels.
+	for _, spendClients := range b.spendNotifications {
+		for _, spendClient := range spendClients {
+			close(spendClient.spendChan)
+		}
+	}
+	for _, epochClient := range b.blockEpochClients {
+		close(epochClient.epochChan)
+	}
+	b.txConfNotifier.TearDown()
+
+	return nil
+}
+
+// blockNtfn packages a notification of a connected/disconnected block along
+// with its height at the time.
+type blockNtfn struct {
+	sha    *chainhash.Hash
+	height int32
+}
+
+// notificationDispatcher is the primary goroutine which handles client
+// notification registrations, as well as notification dispatches.
+func (b *BitcoindNotifier) notificationDispatcher() {
+out:
+	for {
+		select {
+		case cancelMsg := <-b.notificationCancels:
+			switch msg := cancelMsg.(type) {
+			case *spendCancel:
+				chainntnfs.Log.Infof("Cancelling spend "+
+					"notification for out_point=%v, "+
+					"spend_id=%v", msg.op, msg.spendID)
+
+				// Before we attempt to close the spendChan,
+				// ensure that the notification hasn't already
+				// yet been dispatched.
+				if outPointClients, ok := b.spendNotifications[msg.op]; ok {
+					close(outPointClients[msg.spendID].spendChan)
+					delete(b.spendNotifications[msg.op], msg.spendID)
+				}
+
+			case *epochCancel:
+				chainntnfs.Log.Infof("Cancelling epoch "+
+					"notification, epoch_id=%v", msg.epochID)
+
+				// First, close the cancel channel for this
+				// specific client, and wait for the client to
+				// exit.
+				close(b.blockEpochClients[msg.epochID].cancelChan)
+				b.blockEpochClients[msg.epochID].wg.Wait()
+
+				// Once the client has exited, we can then
+				// safely close the channel used to send epoch
+				// notifications, in order to notify any
+				// listeners that the intent has been
+				// cancelled.
+				close(b.blockEpochClients[msg.epochID].epochChan)
+				delete(b.blockEpochClients, msg.epochID)
+
+			}
+		case registerMsg := <-b.notificationRegistry:
+			switch msg := registerMsg.(type) {
+			case *spendNotification:
+				chainntnfs.Log.Infof("New spend subscription: "+
+					"utxo=%v", msg.targetOutpoint)
+				op := *msg.targetOutpoint
+
+				if _, ok := b.spendNotifications[op]; !ok {
+					b.spendNotifications[op] = make(map[uint64]*spendNotification)
+				}
+				b.spendNotifications[op][msg.spendID] = msg
+				b.chainConn.NotifySpent([]*wire.OutPoint{&op})
+			case *confirmationsNotification:
+				chainntnfs.Log.Infof("New confirmations "+
+					"subscription: txid=%v, numconfs=%v",
+					msg.TxID, msg.NumConfirmations)
+
+				// Lookup whether the transaction is already included in the
+				// active chain.
+				txConf, err := b.historicalConfDetails(msg.TxID)
+				if err != nil {
+					chainntnfs.Log.Error(err)
+				}
+				b.heightMtx.RLock()
+				err = b.txConfNotifier.Register(&msg.ConfNtfn, txConf)
+				if err != nil {
+					chainntnfs.Log.Error(err)
+				}
+				b.heightMtx.RUnlock()
+			case *blockEpochRegistration:
+				chainntnfs.Log.Infof("New block epoch subscription")
+				b.blockEpochClients[msg.epochID] = msg
+			}
+
+		case ntfn := <-b.chainConn.Notifications():
+			switch item := ntfn.(type) {
+			case chain.BlockConnected:
+				b.heightMtx.Lock()
+				if item.Height != b.bestHeight+1 {
+					chainntnfs.Log.Warnf("Received blocks out of order: "+
+						"current height=%d, new height=%d",
+						b.bestHeight, item.Height)
+					b.heightMtx.Unlock()
+					continue
+				}
+				b.bestHeight = item.Height
+
+				rawBlock, err := b.chainConn.GetBlock(&item.Hash)
+				if err != nil {
+					chainntnfs.Log.Errorf("Unable to get block: %v", err)
+					b.heightMtx.Unlock()
+					continue
+				}
+
+				chainntnfs.Log.Infof("New block: height=%v, sha=%v",
+					item.Height, item.Hash)
+
+				b.notifyBlockEpochs(item.Height, &item.Hash)
+
+				txns := btcutil.NewBlock(rawBlock).Transactions()
+				err = b.txConfNotifier.ConnectTip(&item.Hash,
+					uint32(item.Height), txns)
+				if err != nil {
+					chainntnfs.Log.Error(err)
+				}
+				b.heightMtx.Unlock()
+				continue
+
+			case chain.BlockDisconnected:
+				b.heightMtx.Lock()
+				if item.Height != b.bestHeight {
+					chainntnfs.Log.Warnf("Received blocks "+
+						"out of order: current height="+
+						"%d, disconnected height=%d",
+						b.bestHeight, item.Height)
+					b.heightMtx.Unlock()
+					continue
+				}
+				b.bestHeight = item.Height - 1
+
+				chainntnfs.Log.Infof("Block disconnected from "+
+					"main chain: height=%v, sha=%v",
+					item.Height, item.Hash)
+
+				err := b.txConfNotifier.DisconnectTip(
+					uint32(item.Height))
+				if err != nil {
+					chainntnfs.Log.Error(err)
+				}
+				b.heightMtx.Unlock()
+
+			case chain.RelevantTx:
+				tx := item.TxRecord.MsgTx
+				// First, check if this transaction spends an output
+				// that has an existing spend notification for it.
+				for i, txIn := range tx.TxIn {
+					prevOut := txIn.PreviousOutPoint
+
+					// If this transaction indeed does spend an
+					// output which we have a registered
+					// notification for, then create a spend
+					// summary, finally sending off the details to
+					// the notification subscriber.
+					if clients, ok := b.spendNotifications[prevOut]; ok {
+						spenderSha := tx.TxHash()
+						spendDetails := &chainntnfs.SpendDetail{
+							SpentOutPoint:     &prevOut,
+							SpenderTxHash:     &spenderSha,
+							SpendingTx:        &tx,
+							SpenderInputIndex: uint32(i),
+						}
+						// TODO(roasbeef): after change to
+						// loadfilter, only notify on block
+						// inclusion?
+						if item.Block != nil {
+							spendDetails.SpendingHeight = item.Block.Height
+						} else {
+							b.heightMtx.RLock()
+							spendDetails.SpendingHeight = b.bestHeight + 1
+							b.heightMtx.RUnlock()
+						}
+
+						for _, ntfn := range clients {
+							chainntnfs.Log.Infof("Dispatching "+
+								"spend notification for "+
+								"outpoint=%v", ntfn.targetOutpoint)
+							ntfn.spendChan <- spendDetails
+
+							// Close spendChan to ensure that any calls to Cancel will not
+							// block. This is safe to do since the channel is buffered, and the
+							// message can still be read by the receiver.
+							close(ntfn.spendChan)
+						}
+						delete(b.spendNotifications, prevOut)
+					}
+				}
+			}
+
+		case <-b.quit:
+			break out
+		}
+	}
+	b.wg.Done()
+}
+
+// historicalConfDetails looks up whether a transaction is already included in a
+// block in the active chain and, if so, returns details about the confirmation.
+func (b *BitcoindNotifier) historicalConfDetails(txid *chainhash.Hash,
+) (*chainntnfs.TxConfirmation, error) {
+
+	// If the transaction already has some or all of the confirmations,
+	// then we may be able to dispatch it immediately.
+	// TODO: fall back to scanning blocks if txindex isn't on.
+	tx, err := b.chainConn.GetRawTransactionVerbose(txid)
+	if err != nil || tx == nil || tx.BlockHash == "" {
+		if err == nil {
+			return nil, nil
+		}
+		// Do not return an error if the transaction was not found.
+		if jsonErr, ok := err.(*btcjson.RPCError); ok {
+			if jsonErr.Code == btcjson.ErrRPCNoTxInfo {
+				return nil, nil
+			}
+		}
+		return nil, fmt.Errorf("unable to query for txid(%v): %v", txid, err)
+	}
+
+	// As we need to fully populate the returned TxConfirmation struct,
+	// grab the block in which the transaction was confirmed so we can
+	// locate its exact index within the block.
+	blockHash, err := chainhash.NewHashFromStr(tx.BlockHash)
+	if err != nil {
+		return nil, fmt.Errorf("unable to get block hash %v for historical "+
+			"dispatch: %v", tx.BlockHash, err)
+	}
+	block, err := b.chainConn.GetBlockVerbose(blockHash)
+	if err != nil {
+		return nil, fmt.Errorf("unable to get block hash: %v", err)
+	}
+
+	// If the block obtained, locate the transaction's index within the
+	// block so we can give the subscriber full confirmation details.
+	txIndex := -1
+	targetTxidStr := txid.String()
+	for i, txHash := range block.Tx {
+		if txHash == targetTxidStr {
+			txIndex = i
+			break
+		}
+	}
+
+	if txIndex == -1 {
+		return nil, fmt.Errorf("unable to locate tx %v in block %v",
+			txid, blockHash)
+	}
+
+	txConf := chainntnfs.TxConfirmation{
+		BlockHash:   blockHash,
+		BlockHeight: uint32(block.Height),
+		TxIndex:     uint32(txIndex),
+	}
+	return &txConf, nil
+}
+
+// notifyBlockEpochs notifies all registered block epoch clients of the newly
+// connected block to the main chain.
+func (b *BitcoindNotifier) notifyBlockEpochs(newHeight int32, newSha *chainhash.Hash) {
+	epoch := &chainntnfs.BlockEpoch{
+		Height: newHeight,
+		Hash:   newSha,
+	}
+
+	for _, epochClient := range b.blockEpochClients {
+		b.wg.Add(1)
+		epochClient.wg.Add(1)
+		go func(ntfnChan chan *chainntnfs.BlockEpoch, cancelChan chan struct{},
+			clientWg *sync.WaitGroup) {
+
+			// TODO(roasbeef): move to goroutine per client, use sync queue
+
+			defer clientWg.Done()
+			defer b.wg.Done()
+
+			select {
+			case ntfnChan <- epoch:
+
+			case <-cancelChan:
+				return
+
+			case <-b.quit:
+				return
+			}
+
+		}(epochClient.epochChan, epochClient.cancelChan, &epochClient.wg)
+	}
+}
+
+// spendNotification couples a target outpoint along with the channel used for
+// notifications once a spend of the outpoint has been detected.
+type spendNotification struct {
+	targetOutpoint *wire.OutPoint
+
+	spendChan chan *chainntnfs.SpendDetail
+
+	spendID uint64
+}
+
+// spendCancel is a message sent to the BitcoindNotifier when a client wishes
+// to cancel an outstanding spend notification that has yet to be dispatched.
+type spendCancel struct {
+	// op is the target outpoint of the notification to be cancelled.
+	op wire.OutPoint
+
+	// spendID the ID of the notification to cancel.
+	spendID uint64
+}
+
+// RegisterSpendNtfn registers an intent to be notified once the target
+// outpoint has been spent by a transaction on-chain. Once a spend of the target
+// outpoint has been detected, the details of the spending event will be sent
+// across the 'Spend' channel.
+func (b *BitcoindNotifier) RegisterSpendNtfn(outpoint *wire.OutPoint,
+	_ uint32) (*chainntnfs.SpendEvent, error) {
+
+	if err := b.chainConn.NotifySpent([]*wire.OutPoint{outpoint}); err != nil {
+		return nil, err
+	}
+
+	ntfn := &spendNotification{
+		targetOutpoint: outpoint,
+		spendChan:      make(chan *chainntnfs.SpendDetail, 1),
+		spendID:        atomic.AddUint64(&b.spendClientCounter, 1),
+	}
+
+	select {
+	case <-b.quit:
+		return nil, ErrChainNotifierShuttingDown
+	case b.notificationRegistry <- ntfn:
+	}
+
+	// The following conditional checks to ensure that when a spend notification
+	// is registered, the output hasn't already been spent. If the output
+	// is no longer in the UTXO set, the chain will be rescanned from the point
+	// where the output was added. The rescan will dispatch the notification.
+	txout, err := b.chainConn.GetTxOut(&outpoint.Hash, outpoint.Index, true)
+	if err != nil {
+		return nil, err
+	}
+
+	if txout == nil {
+		// TODO: fall back to scanning blocks if txindex isn't on.
+		transaction, err := b.chainConn.GetRawTransactionVerbose(&outpoint.Hash)
+		if err != nil {
+			jsonErr, ok := err.(*btcjson.RPCError)
+			if !ok || jsonErr.Code != btcjson.ErrRPCNoTxInfo {
+				return nil, err
+			}
+		}
+
+		if transaction != nil {
+			blockhash, err := chainhash.NewHashFromStr(transaction.BlockHash)
+			if err != nil {
+				return nil, err
+			}
+
+			// Rewind the rescan, since the btcwallet bitcoind
+			// back-end doesn't support that.
+			blockHeight, err := b.chainConn.GetBlockHeight(blockhash)
+			if err != nil {
+				return nil, err
+			}
+			b.heightMtx.Lock()
+			currentHeight := b.bestHeight
+			b.bestHeight = blockHeight
+			for i := currentHeight; i > blockHeight; i-- {
+				err = b.txConfNotifier.DisconnectTip(uint32(i))
+				if err != nil {
+					return nil, err
+				}
+			}
+			b.heightMtx.Unlock()
+
+			ops := []*wire.OutPoint{outpoint}
+			if err := b.chainConn.Rescan(blockhash, nil, ops); err != nil {
+				chainntnfs.Log.Errorf("Rescan for spend "+
+					"notification txout failed: %v", err)
+				return nil, err
+			}
+		}
+	}
+
+	return &chainntnfs.SpendEvent{
+		Spend: ntfn.spendChan,
+		Cancel: func() {
+			cancel := &spendCancel{
+				op:      *outpoint,
+				spendID: ntfn.spendID,
+			}
+
+			// Submit spend cancellation to notification dispatcher.
+			select {
+			case b.notificationCancels <- cancel:
+				// Cancellation is being handled, drain the spend chan until it is
+				// closed before yielding to the caller.
+				for {
+					select {
+					case _, ok := <-ntfn.spendChan:
+						if !ok {
+							return
+						}
+					case <-b.quit:
+						return
+					}
+				}
+			case <-b.quit:
+			}
+		},
+	}, nil
+}
+
+// confirmationNotification represents a client's intent to receive a
+// notification once the target txid reaches numConfirmations confirmations.
+type confirmationsNotification struct {
+	chainntnfs.ConfNtfn
+}
+
+// RegisterConfirmationsNtfn registers a notification with BitcoindNotifier
+// which will be triggered once the txid reaches numConfs number of
+// confirmations.
+func (b *BitcoindNotifier) RegisterConfirmationsNtfn(txid *chainhash.Hash,
+	numConfs, _ uint32) (*chainntnfs.ConfirmationEvent, error) {
+
+	ntfn := &confirmationsNotification{
+		chainntnfs.ConfNtfn{
+			TxID:             txid,
+			NumConfirmations: numConfs,
+			Event:            chainntnfs.NewConfirmationEvent(),
+		},
+	}
+
+	select {
+	case <-b.quit:
+		return nil, ErrChainNotifierShuttingDown
+	case b.notificationRegistry <- ntfn:
+		return ntfn.Event, nil
+	}
+}
+
+// blockEpochRegistration represents a client's intent to receive a
+// notification with each newly connected block.
+type blockEpochRegistration struct {
+	epochID uint64
+
+	epochChan chan *chainntnfs.BlockEpoch
+
+	cancelChan chan struct{}
+
+	wg sync.WaitGroup
+}
+
+// epochCancel is a message sent to the BitcoindNotifier when a client wishes
+// to cancel an outstanding epoch notification that has yet to be dispatched.
+type epochCancel struct {
+	epochID uint64
+}
+
+// RegisterBlockEpochNtfn returns a BlockEpochEvent which subscribes the
+// caller to receive notifications, of each new block connected to the main
+// chain.
+func (b *BitcoindNotifier) RegisterBlockEpochNtfn() (*chainntnfs.BlockEpochEvent, error) {
+	registration := &blockEpochRegistration{
+		epochChan:  make(chan *chainntnfs.BlockEpoch, 20),
+		cancelChan: make(chan struct{}),
+		epochID:    atomic.AddUint64(&b.epochClientCounter, 1),
+	}
+
+	select {
+	case <-b.quit:
+		return nil, errors.New("chainntnfs: system interrupt while " +
+			"attempting to register for block epoch notification.")
+	case b.notificationRegistry <- registration:
+		return &chainntnfs.BlockEpochEvent{
+			Epochs: registration.epochChan,
+			Cancel: func() {
+				cancel := &epochCancel{
+					epochID: registration.epochID,
+				}
+
+				// Submit epoch cancellation to notification dispatcher.
+				select {
+				case b.notificationCancels <- cancel:
+					// Cancellation is being handled, drain the epoch channel until it is
+					// closed before yielding to caller.
+					for {
+						select {
+						case _, ok := <-registration.epochChan:
+							if !ok {
+								return
+							}
+						case <-b.quit:
+							return
+						}
+					}
+				case <-b.quit:
+				}
+			},
+		}, nil
+	}
+}

chainntnfs/bitcoindnotify/driver.go

@@ -0,0 +1,53 @@
+package bitcoindnotify
+
+import (
+	"fmt"
+
+	"github.com/lightningnetwork/lnd/chainntnfs"
+	"github.com/roasbeef/btcd/chaincfg"
+	"github.com/roasbeef/btcd/rpcclient"
+)
+
+// createNewNotifier creates a new instance of the ChainNotifier interface
+// implemented by BitcoindNotifier.
+func createNewNotifier(args ...interface{}) (chainntnfs.ChainNotifier, error) {
+	if len(args) != 3 {
+		return nil, fmt.Errorf("incorrect number of arguments to "+
+			".New(...), expected 3, instead passed %v", len(args))
+	}
+
+	config, ok := args[0].(*rpcclient.ConnConfig)
+	if !ok {
+		return nil, fmt.Errorf("first argument to bitcoindnotifier." +
+			"New is incorrect, expected a *rpcclient.ConnConfig")
+	}
+
+	zmqConnect, ok := args[1].(string)
+	if !ok {
+		return nil, fmt.Errorf("second argument to bitcoindnotifier." +
+			"New is incorrect, expected a string")
+	}
+
+	params, ok := args[2].(chaincfg.Params)
+	if !ok {
+		return nil, fmt.Errorf("third argument to bitcoindnotifier." +
+			"New is incorrect, expected a chaincfg.Params")
+	}
+
+	return New(config, zmqConnect, params)
+}
+
+// init registers a driver for the BtcdNotifier concrete implementation of the
+// chainntnfs.ChainNotifier interface.
+func init() {
+	// Register the driver.
+	notifier := &chainntnfs.NotifierDriver{
+		NotifierType: notifierType,
+		New:          createNewNotifier,
+	}
+
+	if err := chainntnfs.RegisterNotifier(notifier); err != nil {
+		panic(fmt.Sprintf("failed to register notifier driver '%s': %v",
+			notifierType, err))
+	}
+}

chainntnfs/interface_test.go

@@ -5,7 +5,9 @@ import (
 	"fmt"
 	"io/ioutil"
 	"log"
+	"math/rand"
 	"os"
+	"os/exec"
 	"path/filepath"
 	"sync"
 	"testing"
@@ -13,6 +15,7 @@ import (
 
 	"github.com/lightninglabs/neutrino"
 	"github.com/lightningnetwork/lnd/chainntnfs"
+	"github.com/ltcsuite/ltcd/btcjson"
 	"github.com/roasbeef/btcd/chaincfg/chainhash"
 	"github.com/roasbeef/btcwallet/walletdb"
 
@@ -24,6 +27,10 @@ import (
 	"github.com/roasbeef/btcd/wire"
 	"github.com/roasbeef/btcutil"
 
+	// Required to auto-register the bitcoind backed ChainNotifier
+	// implementation.
+	_ "github.com/lightningnetwork/lnd/chainntnfs/bitcoindnotify"
+
 	// Required to auto-register the btcd backed ChainNotifier
 	// implementation.
 	_ "github.com/lightningnetwork/lnd/chainntnfs/btcdnotify"
@@ -32,7 +39,8 @@ import (
 	// implementation.
 	_ "github.com/lightningnetwork/lnd/chainntnfs/neutrinonotify"
 
-	_ "github.com/roasbeef/btcwallet/walletdb/bdb" // Required to register the boltdb walletdb implementation.
+	// Required to register the boltdb walletdb implementation.
+	_ "github.com/roasbeef/btcwallet/walletdb/bdb"
 )
 
 var (
@@ -43,7 +51,7 @@ var (
 		0x1e, 0xb, 0x4c, 0xfd, 0x9e, 0xc5, 0x8c, 0xe9,
 	}
 
-	netParams       = &chaincfg.SimNetParams
+	netParams       = &chaincfg.RegressionNetParams
 	privKey, pubKey = btcec.PrivKeyFromBytes(btcec.S256(), testPrivKey)
 	addrPk, _       = btcutil.NewAddressPubKey(pubKey.SerializeCompressed(),
 		netParams)
@@ -65,6 +73,39 @@ func getTestTxId(miner *rpctest.Harness) (*chainhash.Hash, error) {
 	return miner.SendOutputs(outputs, 10)
 }
 
+func waitForMempoolTx(r *rpctest.Harness, txid *chainhash.Hash) error {
+	var found bool
+	var tx *btcutil.Tx
+	var err error
+	timeout := time.After(10 * time.Second)
+	for !found {
+		// Do a short wait
+		select {
+		case <-timeout:
+			return fmt.Errorf("timeout after 10s")
+		default:
+		}
+		time.Sleep(100 * time.Millisecond)
+
+		// Check for the harness' knowledge of the txid
+		tx, err = r.Node.GetRawTransaction(txid)
+		if err != nil {
+			switch e := err.(type) {
+			case *btcjson.RPCError:
+				if e.Code == btcjson.ErrRPCNoTxInfo {
+					continue
+				}
+			default:
+			}
+			return err
+		}
+		if tx != nil && tx.MsgTx().TxHash() == *txid {
+			found = true
+		}
+	}
+	return nil
+}
+
 func testSingleConfirmationNotification(miner *rpctest.Harness,
 	notifier chainntnfs.ChainNotifier, t *testing.T) {
 
@@ -80,6 +121,11 @@ func testSingleConfirmationNotification(miner *rpctest.Harness,
 		t.Fatalf("unable to create test tx: %v", err)
 	}
 
+	err = waitForMempoolTx(miner, txid)
+	if err != nil {
+		t.Fatalf("tx not relayed to miner: %v", err)
+	}
+
 	_, currentHeight, err := miner.Node.GetBestBlock()
 	if err != nil {
 		t.Fatalf("unable to get current height: %v", err)
@@ -143,6 +189,11 @@ func testMultiConfirmationNotification(miner *rpctest.Harness,
 		t.Fatalf("unable to create test addr: %v", err)
 	}
 
+	err = waitForMempoolTx(miner, txid)
+	if err != nil {
+		t.Fatalf("tx not relayed to miner: %v", err)
+	}
+
 	_, currentHeight, err := miner.Node.GetBestBlock()
 	if err != nil {
 		t.Fatalf("unable to get current height: %v", err)
@@ -201,6 +252,11 @@ func testBatchConfirmationNotification(miner *rpctest.Harness,
 			t.Fatalf("unable to register ntfn: %v", err)
 		}
 		confIntents[i] = confIntent
+		err = waitForMempoolTx(miner, txid)
+		if err != nil {
+			t.Fatalf("tx not relayed to miner: %v", err)
+		}
+
 	}
 
 	initialConfHeight := uint32(currentHeight + 1)
@@ -252,6 +308,11 @@ func createSpendableOutput(miner *rpctest.Harness,
 		t.Fatalf("unable to create test addr: %v", err)
 	}
 
+	err = waitForMempoolTx(miner, txid)
+	if err != nil {
+		t.Fatalf("tx not relayed to miner: %v", err)
+	}
+
 	// Mine a single block which should include that txid above.
 	if _, err := miner.Node.Generate(1); err != nil {
 		t.Fatalf("unable to generate single block: %v", err)
@@ -342,6 +403,11 @@ func testSpendNotification(miner *rpctest.Harness,
 		t.Fatalf("unable to broadcast tx: %v", err)
 	}
 
+	err = waitForMempoolTx(miner, spenderSha)
+	if err != nil {
+		t.Fatalf("tx not relayed to miner: %v", err)
+	}
+
 	// Now we mine a single block, which should include our spend. The
 	// notification should also be sent off.
 	if _, err := miner.Node.Generate(1); err != nil {
@@ -453,6 +519,11 @@ func testMultiClientConfirmationNotification(miner *rpctest.Harness,
 		t.Fatalf("unable to create test tx: %v", err)
 	}
 
+	err = waitForMempoolTx(miner, txid)
+	if err != nil {
+		t.Fatalf("tx not relayed to miner: %v", err)
+	}
+
 	var wg sync.WaitGroup
 	const (
 		numConfsClients = 5
@@ -514,6 +585,11 @@ func testTxConfirmedBeforeNtfnRegistration(miner *rpctest.Harness,
 		t.Fatalf("unable to create test tx: %v", err)
 	}
 
+	err = waitForMempoolTx(miner, txid3)
+	if err != nil {
+		t.Fatalf("tx not relayed to miner: %v", err)
+	}
+
 	// Generate another block containing tx 3, but we won't register conf
 	// notifications for this tx until much later. The notifier must check
 	// older blocks when the confirmation event is registered below to ensure
@@ -529,11 +605,21 @@ func testTxConfirmedBeforeNtfnRegistration(miner *rpctest.Harness,
 		t.Fatalf("unable to create test tx: %v", err)
 	}
 
+	err = waitForMempoolTx(miner, txid1)
+	if err != nil {
+		t.Fatalf("tx not relayed to miner: %v", err)
+	}
+
 	txid2, err := getTestTxId(miner)
 	if err != nil {
 		t.Fatalf("unable to create test tx: %v", err)
 	}
 
+	err = waitForMempoolTx(miner, txid2)
+	if err != nil {
+		t.Fatalf("tx not relayed to miner: %v", err)
+	}
+
 	_, currentHeight, err := miner.Node.GetBestBlock()
 	if err != nil {
 		t.Fatalf("unable to get current height: %v", err)
@@ -654,6 +740,11 @@ func testLazyNtfnConsumer(miner *rpctest.Harness,
 		t.Fatalf("unable to create test tx: %v", err)
 	}
 
+	err = waitForMempoolTx(miner, txid)
+	if err != nil {
+		t.Fatalf("tx not relayed to miner: %v", err)
+	}
+
 	_, currentHeight, err := miner.Node.GetBestBlock()
 	if err != nil {
 		t.Fatalf("unable to get current height: %v", err)
@@ -686,6 +777,11 @@ func testLazyNtfnConsumer(miner *rpctest.Harness,
 		t.Fatalf("unable to create test tx: %v", err)
 	}
 
+	err = waitForMempoolTx(miner, txid)
+	if err != nil {
+		t.Fatalf("tx not relayed to miner: %v", err)
+	}
+
 	_, currentHeight, err = miner.Node.GetBestBlock()
 	if err != nil {
 		t.Fatalf("unable to get current height: %v", err)
@@ -736,6 +832,11 @@ func testSpendBeforeNtfnRegistration(miner *rpctest.Harness,
 		t.Fatalf("unable to create test addr: %v", err)
 	}
 
+	err = waitForMempoolTx(miner, txid)
+	if err != nil {
+		t.Fatalf("tx not relayed to miner: %v", err)
+	}
+
 	// Mine a single block which should include that txid above.
 	if _, err := miner.Node.Generate(1); err != nil {
 		t.Fatalf("unable to generate single block: %v", err)
@@ -789,6 +890,11 @@ func testSpendBeforeNtfnRegistration(miner *rpctest.Harness,
 		t.Fatalf("unable to brodacst tx: %v", err)
 	}
 
+	err = waitForMempoolTx(miner, spenderSha)
+	if err != nil {
+		t.Fatalf("tx not relayed to miner: %v", err)
+	}
+
 	// Now we mine an additional block, which should include our spend.
 	if _, err := miner.Node.Generate(1); err != nil {
 		t.Fatalf("unable to generate single block: %v", err)
@@ -877,6 +983,11 @@ func testCancelSpendNtfn(node *rpctest.Harness,
 		t.Fatalf("unable to brodacst tx: %v", err)
 	}
 
+	err = waitForMempoolTx(node, spenderSha)
+	if err != nil {
+		t.Fatalf("tx not relayed to miner: %v", err)
+	}
+
 	// Now we mine a single block, which should include our spend. The
 	// notification should also be sent off.
 	if _, err := node.Node.Generate(1); err != nil {
@@ -1021,6 +1132,11 @@ func testReorgConf(miner *rpctest.Harness, notifier chainntnfs.ChainNotifier,
 		t.Fatalf("unable to create test tx: %v", err)
 	}
 
+	err = waitForMempoolTx(miner, txid)
+	if err != nil {
+		t.Fatalf("tx not relayed to miner: %v", err)
+	}
+
 	_, currentHeight, err := miner.Node.GetBestBlock()
 	if err != nil {
 		t.Fatalf("unable to get current height: %v", err)
@@ -1094,11 +1210,16 @@ func testReorgConf(miner *rpctest.Harness, notifier chainntnfs.ChainNotifier,
 		t.Fatalf("unable to get raw tx: %v", err)
 	}
 
-	_, err = miner2.Node.SendRawTransaction(tx.MsgTx(), false)
+	txid, err = miner2.Node.SendRawTransaction(tx.MsgTx(), false)
 	if err != nil {
 		t.Fatalf("unable to get send tx: %v", err)
 	}
 
+	err = waitForMempoolTx(miner, txid)
+	if err != nil {
+		t.Fatalf("tx not relayed to miner: %v", err)
+	}
+
 	_, err = miner.Node.Generate(3)
 	if err != nil {
 		t.Fatalf("unable to generate single block: %v", err)
@@ -1206,12 +1327,73 @@ func TestInterfaces(t *testing.T) {
 
 		switch notifierType {
 
+		case "bitcoind":
+			// Start a bitcoind instance.
+			tempBitcoindDir, err := ioutil.TempDir("", "bitcoind")
+			if err != nil {
+				t.Fatalf("Unable to create temp dir: %v", err)
+			}
+			zmqPath := "ipc:///" + tempBitcoindDir + "/weks.socket"
+			cleanUp1 := func() {
+				os.RemoveAll(tempBitcoindDir)
+			}
+			cleanUp = cleanUp1
+			rpcPort := rand.Int()%(65536-1024) + 1024
+			bitcoind := exec.Command(
+				"bitcoind",
+				"-datadir="+tempBitcoindDir,
+				"-regtest",
+				"-connect="+p2pAddr,
+				"-txindex",
+				"-rpcauth=weks:469e9bb14ab2360f8e226efed5ca6f"+
+					"d$507c670e800a95284294edb5773b05544b"+
+					"220110063096c221be9933c82d38e1",
+				fmt.Sprintf("-rpcport=%d", rpcPort),
+				"-disablewallet",
+				"-zmqpubrawblock="+zmqPath,
+				"-zmqpubrawtx="+zmqPath,
+			)
+			err = bitcoind.Start()
+			if err != nil {
+				cleanUp1()
+				t.Fatalf("Couldn't start bitcoind: %v", err)
+			}
+			cleanUp2 := func() {
+				bitcoind.Process.Kill()
+				bitcoind.Wait()
+				cleanUp1()
+			}
+			cleanUp = cleanUp2
+
+			// Wait for the bitcoind instance to start up.
+			time.Sleep(time.Second)
+
+			// Start the FilteredChainView implementation instance.
+			config := rpcclient.ConnConfig{
+				Host: fmt.Sprintf(
+					"127.0.0.1:%d", rpcPort),
+				User:                 "weks",
+				Pass:                 "weks",
+				DisableAutoReconnect: false,
+				DisableConnectOnNew:  true,
+				DisableTLS:           true,
+				HTTPPostMode:         true,
+			}
+
+			notifier, err = notifierDriver.New(&config, zmqPath,
+				*netParams)
+			if err != nil {
+				t.Fatalf("unable to create %v notifier: %v",
+					notifierType, err)
+			}
+
 		case "btcd":
 			notifier, err = notifierDriver.New(&rpcConfig)
 			if err != nil {
 				t.Fatalf("unable to create %v notifier: %v",
 					notifierType, err)
 			}
+			cleanUp = func() {}
 
 		case "neutrino":
 			spvDir, err := ioutil.TempDir("", "neutrino")

glide.lock

@@ -1,5 +1,5 @@
-hash: 8438e391bed32638a8e14402992af50b7656b380f69741cf8422584c2e1f2b31
-updated: 2017-12-13T15:13:22.311098343-08:00
+hash: d145c16f2f9cfdf4937eb8b7cdd65919a8c351593a179acc23f2cbca5b42f34b
+updated: 2017-12-22T23:45:25.148488338-07:00
 imports:
 - name: github.com/aead/chacha20
   version: d31a916ded42d1640b9d89a26f8abd53cc96790c
@@ -86,6 +86,8 @@ imports:
   version: 946bd9fbed05568b0f3cd188353d8aa28f38b688
   subpackages:
   - internal/socket
+- name: github.com/pebbe/zmq4
+  version: 90d69e412a09549f2e90bac70fbb449081f1e5c1
 - name: github.com/roasbeef/btcd
   version: 9978b939c33973be19b932fa7b936079bb7ba38d
   subpackages:

glide.yaml

@@ -24,6 +24,7 @@ import:
   - txscript
   - wire
   - connmgr
+- package: github.com/pebbe/zmq4
 - package: github.com/roasbeef/btcrpcclient
   version: d0f4db8b4dad0ca3d569b804f21247c3dd96acbb
 - package: github.com/roasbeef/btcutil

lnwallet/btcwallet/blockchain.go

@@ -29,23 +29,7 @@ var (
 //
 // This method is a part of the lnwallet.BlockChainIO interface.
 func (b *BtcWallet) GetBestBlock() (*chainhash.Hash, int32, error) {
-	switch backend := b.chain.(type) {
-
-	case *chain.NeutrinoClient:
-		header, height, err := backend.CS.BlockHeaders.ChainTip()
-		if err != nil {
-			return nil, -1, err
-		}
-
-		blockHash := header.BlockHash()
-		return &blockHash, int32(height), nil
-
-	case *chain.RPCClient:
-		return backend.GetBestBlock()
-
-	default:
-		return nil, -1, fmt.Errorf("unknown backend")
-	}
+	return b.chain.GetBestBlock()
 }
 
 // GetUtxo returns the original output referenced by the passed outpoint.
@@ -100,6 +84,26 @@ func (b *BtcWallet) GetUtxo(op *wire.OutPoint, heightHint uint32) (*wire.TxOut,
 			PkScript: pkScript,
 		}, nil
 
+	case *chain.BitcoindClient:
+		txout, err := backend.GetTxOut(&op.Hash, op.Index, false)
+		if err != nil {
+			return nil, err
+		} else if txout == nil {
+			return nil, ErrOutputSpent
+		}
+
+		pkScript, err := hex.DecodeString(txout.ScriptPubKey.Hex)
+		if err != nil {
+			return nil, err
+		}
+
+		return &wire.TxOut{
+			// Sadly, gettxout returns the output value in BTC
+			// instead of satoshis.
+			Value:    int64(txout.Value * 1e8),
+			PkScript: pkScript,
+		}, nil
+
 	default:
 		return nil, fmt.Errorf("unknown backend")
 	}
@@ -109,27 +113,7 @@ func (b *BtcWallet) GetUtxo(op *wire.OutPoint, heightHint uint32) (*wire.TxOut,
 //
 // This method is a part of the lnwallet.BlockChainIO interface.
 func (b *BtcWallet) GetBlock(blockHash *chainhash.Hash) (*wire.MsgBlock, error) {
-	switch backend := b.chain.(type) {
-
-	case *chain.NeutrinoClient:
-		block, err := backend.CS.GetBlockFromNetwork(*blockHash)
-		if err != nil {
-			return nil, err
-		}
-
-		return block.MsgBlock(), nil
-
-	case *chain.RPCClient:
-		block, err := backend.GetBlock(blockHash)
-		if err != nil {
-			return nil, err
-		}
-
-		return block, nil
-
-	default:
-		return nil, fmt.Errorf("unknown backend")
-	}
+	return b.chain.GetBlock(blockHash)
 }
 
 // GetBlockHash returns the hash of the block in the best blockchain at the
@@ -137,29 +121,7 @@ func (b *BtcWallet) GetBlock(blockHash *chainhash.Hash) (*wire.MsgBlock, error)
 //
 // This method is a part of the lnwallet.BlockChainIO interface.
 func (b *BtcWallet) GetBlockHash(blockHeight int64) (*chainhash.Hash, error) {
-	switch backend := b.chain.(type) {
-
-	case *chain.NeutrinoClient:
-		height := uint32(blockHeight)
-		blockHeader, err := backend.CS.BlockHeaders.FetchHeaderByHeight(height)
-		if err != nil {
-			return nil, err
-		}
-
-		blockHash := blockHeader.BlockHash()
-		return &blockHash, nil
-
-	case *chain.RPCClient:
-		blockHash, err := backend.GetBlockHash(blockHeight)
-		if err != nil {
-			return nil, err
-		}
-
-		return blockHash, nil
-
-	default:
-		return nil, fmt.Errorf("unknown backend")
-	}
+	return b.chain.GetBlockHash(blockHeight)
 }
 
 // A compile time check to ensure that BtcWallet implements the BlockChainIO

lnwallet/btcwallet/btcwallet.go

@@ -119,6 +119,17 @@ func New(cfg Config) (*BtcWallet, error) {
 	}, nil
 }
 
+// BackEnd returns the underlying ChainService's name as a string.
+//
+// This is a part of the WalletController interface.
+func (b *BtcWallet) BackEnd() string {
+	if b.chain != nil {
+		return b.chain.BackEnd()
+	}
+
+	return ""
+}
+
 // Start initializes the underlying rpc connection, the wallet itself, and
 // begins syncing to the current available blockchain state.
 //
@@ -668,22 +679,9 @@ func (b *BtcWallet) IsSynced() (bool, error) {
 
 	// Next, query the chain backend to grab the info about the tip of the
 	// main chain.
-	switch backend := b.cfg.ChainSource.(type) {
-	case *chain.NeutrinoClient:
-		header, height, err := backend.CS.BlockHeaders.ChainTip()
-		if err != nil {
-			return false, err
-		}
-
-		bh := header.BlockHash()
-		bestHash = &bh
-		bestHeight = int32(height)
-
-	case *chain.RPCClient:
-		bestHash, bestHeight, err = backend.GetBestBlock()
-		if err != nil {
-			return false, err
-		}
+	bestHash, bestHeight, err = b.cfg.ChainSource.GetBestBlock()
+	if err != nil {
+		return false, err
 	}
 
 	// If the wallet hasn't yet fully synced to the node's best chain tip,
@@ -696,21 +694,9 @@ func (b *BtcWallet) IsSynced() (bool, error) {
 	// still may not yet be synced as the chain backend may still be
 	// catching up to the main chain. So we'll grab the block header in
 	// order to make a guess based on the current time stamp.
-	var blockHeader *wire.BlockHeader
-	switch backend := b.cfg.ChainSource.(type) {
-
-	case *chain.NeutrinoClient:
-		bh, _, err := backend.CS.BlockHeaders.FetchHeader(bestHash)
-		if err != nil {
-			return false, err
-		}
-		blockHeader = bh
-
-	case *chain.RPCClient:
-		blockHeader, err = backend.GetBlockHeader(bestHash)
-		if err != nil {
-			return false, err
-		}
+	blockHeader, err := b.cfg.ChainSource.GetBlockHeader(bestHash)
+	if err != nil {
+		return false, err
 	}
 
 	// If the timestamp no the best header is more than 2 hours in the

lnwallet/btcwallet/driver.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 
 	"github.com/lightningnetwork/lnd/lnwallet"
+	"github.com/roasbeef/btcwallet/chain"
 )
 
 const (
@@ -36,6 +37,7 @@ func init() {
 	driver := &lnwallet.WalletDriver{
 		WalletType: walletType,
 		New:        createNewWallet,
+		BackEnds:   chain.BackEnds,
 	}
 
 	if err := lnwallet.RegisterWallet(driver); err != nil {

lnwallet/fee_estimator.go

@@ -1,6 +1,8 @@
 package lnwallet
 
 import (
+	"encoding/json"
+
 	"github.com/roasbeef/btcd/blockchain"
 	"github.com/roasbeef/btcd/rpcclient"
 	"github.com/roasbeef/btcutil"
@@ -200,3 +202,145 @@ func (b *BtcdFeeEstimator) fetchEstimatePerByte(confTarget uint32) (btcutil.Amou
 // A compile-time assertion to ensure that BtcdFeeEstimator implements the
 // FeeEstimator interface.
 var _ FeeEstimator = (*BtcdFeeEstimator)(nil)
+
+// BitcoindFeeEstimator is an implementation of the FeeEstimator interface
+// backed by the RPC interface of an active bitcoind node. This implementation
+// will proxy any fee estimation requests to bitcoind's RPC interace.
+type BitcoindFeeEstimator struct {
+	// fallBackFeeRate is the fall back fee rate in satoshis per byte that
+	// is returned if the fee estimator does not yet have enough data to
+	// actually produce fee estimates.
+	fallBackFeeRate btcutil.Amount
+
+	bitcoindConn *rpcclient.Client
+}
+
+// NewBitcoindFeeEstimator creates a new BitcoindFeeEstimator given a fully
+// populated rpc config that is able to successfully connect and authenticate
+// with the bitcoind node, and also a fall back fee rate. The fallback fee rate
+// is used in the occasion that the estimator has insufficient data, or returns
+// zero for a fee estimate.
+func NewBitcoindFeeEstimator(rpcConfig rpcclient.ConnConfig,
+	fallBackFeeRate btcutil.Amount) (*BitcoindFeeEstimator, error) {
+
+	rpcConfig.DisableConnectOnNew = true
+	rpcConfig.DisableAutoReconnect = false
+	rpcConfig.DisableTLS = true
+	rpcConfig.HTTPPostMode = true
+	chainConn, err := rpcclient.New(&rpcConfig, nil)
+	if err != nil {
+		return nil, err
+	}
+
+	return &BitcoindFeeEstimator{
+		fallBackFeeRate: fallBackFeeRate,
+		bitcoindConn:    chainConn,
+	}, nil
+}
+
+// Start signals the FeeEstimator to start any processes or goroutines
+// it needs to perform its duty.
+//
+// NOTE: This method is part of the FeeEstimator interface.
+func (b *BitcoindFeeEstimator) Start() error {
+	return nil
+}
+
+// Stop stops any spawned goroutines and cleans up the resources used
+// by the fee estimator.
+//
+// NOTE: This method is part of the FeeEstimator interface.
+func (b *BitcoindFeeEstimator) Stop() error {
+	return nil
+}
+
+// EstimateFeePerByte takes in a target for the number of blocks until an
+// initial confirmation and returns the estimated fee expressed in
+// satoshis/byte.
+func (b *BitcoindFeeEstimator) EstimateFeePerByte(numBlocks uint32) (btcutil.Amount, error) {
+	feeEstimate, err := b.fetchEstimatePerByte(numBlocks)
+	switch {
+	// If the estimator doesn't have enough data, or returns an error, then
+	// to return a proper value, then we'll return the default fall back
+	// fee rate.
+	case err != nil:
+		walletLog.Errorf("unable to query estimator: %v", err)
+		fallthrough
+
+	case feeEstimate == 0:
+		return b.fallBackFeeRate, nil
+	}
+
+	return feeEstimate, nil
+}
+
+// EstimateFeePerWeight takes in a target for the number of blocks until an
+// initial confirmation and returns the estimated fee expressed in
+// satoshis/weight.
+func (b *BitcoindFeeEstimator) EstimateFeePerWeight(numBlocks uint32) (btcutil.Amount, error) {
+	feePerByte, err := b.EstimateFeePerByte(numBlocks)
+	if err != nil {
+		return 0, err
+	}
+
+	// We'll scale down the fee per byte to fee per weight, as for each raw
+	// byte, there's 1/4 unit of weight mapped to it.
+	satWeight := feePerByte / blockchain.WitnessScaleFactor
+
+	// If this ends up scaling down to a zero sat/weight amount, then we'll
+	// use the default fallback fee rate.
+	// TODO(aakselrod): maybe use the per-byte rate if it's non-zero?
+	// Otherwise, we can return a higher sat/byte than sat/weight.
+	if satWeight == 0 {
+		return b.fallBackFeeRate / blockchain.WitnessScaleFactor, nil
+	}
+
+	return satWeight, nil
+}
+
+// fetchEstimate returns a fee estimate for a transaction be be confirmed in
+// confTarget blocks. The estimate is returned in sat/byte.
+func (b *BitcoindFeeEstimator) fetchEstimatePerByte(confTarget uint32) (btcutil.Amount, error) {
+	// First, we'll send an "estimatesmartfee" command as a raw request,
+	// since it isn't supported by btcd but is available in bitcoind.
+	target, err := json.Marshal(uint64(confTarget))
+	if err != nil {
+		return 0, err
+	}
+	// TODO: Allow selection of economical/conservative modifiers.
+	resp, err := b.bitcoindConn.RawRequest("estimatesmartfee",
+		[]json.RawMessage{target})
+	if err != nil {
+		return 0, err
+	}
+
+	// Next, we'll parse the response to get the BTC per KB.
+	feeEstimate := struct {
+		Feerate float64 `json:"feerate"`
+	}{}
+	err = json.Unmarshal(resp, &feeEstimate)
+	if err != nil {
+		return 0, err
+	}
+
+	// Next, we'll convert the returned value to satoshis, as it's
+	// currently returned in BTC.
+	satPerKB, err := btcutil.NewAmount(feeEstimate.Feerate)
+	if err != nil {
+		return 0, err
+	}
+
+	// The value returned is expressed in fees per KB, while we want
+	// fee-per-byte, so we'll divide by 1024 to map to satoshis-per-byte
+	// before returning the estimate.
+	satPerByte := satPerKB / 1024
+
+	walletLog.Debugf("Returning %v sat/byte for conf target of %v",
+		int64(satPerByte), confTarget)
+
+	return satPerByte, nil
+}
+
+// A compile-time assertion to ensure that BitcoindFeeEstimator implements the
+// FeeEstimator interface.
+var _ FeeEstimator = (*BitcoindFeeEstimator)(nil)

lnwallet/interface.go

@@ -207,6 +207,11 @@ type WalletController interface {
 	// Stop signals the wallet for shutdown. Shutdown may entail closing
 	// any active sockets, database handles, stopping goroutines, etc.
 	Stop() error
+
+	// BackEnd returns a name for the wallet's backing chain service,
+	// which could be e.g. btcd, bitcoind, neutrino, or another consensus
+	// service.
+	BackEnd() string
 }
 
 // BlockChainIO is a dedicated source which will be used to obtain queries
@@ -288,6 +293,10 @@ type WalletDriver struct {
 	// initialization flexibility, thereby accommodating several potential
 	// WalletController implementations.
 	New func(args ...interface{}) (WalletController, error)
+
+	// BackEnds returns a list of available chain service drivers for the
+	// wallet driver. This could be e.g. bitcoind, btcd, neutrino, etc.
+	BackEnds func() []string
 }
 
 var (

lnwallet/interface_test.go

@@ -5,8 +5,10 @@ import (
 	"encoding/hex"
 	"fmt"
 	"io/ioutil"
+	"math/rand"
 	"net"
 	"os"
+	"os/exec"
 	"path/filepath"
 	"reflect"
 	"runtime"
@@ -17,7 +19,10 @@ import (
 	"github.com/boltdb/bolt"
 	"github.com/davecgh/go-spew/spew"
 
+	"github.com/lightninglabs/neutrino"
 	"github.com/roasbeef/btcwallet/chain"
+	"github.com/roasbeef/btcwallet/walletdb"
+	_ "github.com/roasbeef/btcwallet/walletdb/bdb"
 
 	"github.com/lightningnetwork/lnd/chainntnfs"
 	"github.com/lightningnetwork/lnd/chainntnfs/btcdnotify"
@@ -25,10 +30,10 @@ import (
 	"github.com/lightningnetwork/lnd/lnwallet"
 	"github.com/lightningnetwork/lnd/lnwallet/btcwallet"
 	"github.com/lightningnetwork/lnd/lnwire"
+	"github.com/roasbeef/btcd/btcjson"
 	"github.com/roasbeef/btcd/chaincfg"
 	"github.com/roasbeef/btcd/chaincfg/chainhash"
 	"github.com/roasbeef/btcd/rpcclient"
-	_ "github.com/roasbeef/btcwallet/walletdb/bdb"
 
 	"github.com/roasbeef/btcd/btcec"
 	"github.com/roasbeef/btcd/integration/rpctest"
@@ -76,7 +81,7 @@ var (
 		0x69, 0x49, 0x18, 0x83, 0x31, 0x98, 0x47, 0x53,
 	}
 
-	netParams = &chaincfg.SimNetParams
+	netParams = &chaincfg.RegressionNetParams
 	chainHash = netParams.GenesisHash
 
 	_, alicePub = btcec.PrivKeyFromBytes(btcec.S256(), testHdSeed[:])
@@ -145,6 +150,12 @@ func calcStaticFee(numHTLCs int) btcutil.Amount {
 func loadTestCredits(miner *rpctest.Harness, w *lnwallet.LightningWallet,
 	numOutputs, btcPerOutput int) error {
 
+	// For initial neutrino connection, wait a second.
+	// TODO(aakselrod): Eliminate the need for this.
+	switch w.BackEnd() {
+	case "neutrino":
+		time.Sleep(time.Second)
+	}
 	// Using the mining node, spend from a coinbase output numOutputs to
 	// give us btcPerOutput with each output.
 	satoshiPerOutput := int64(btcPerOutput * 1e8)
@@ -188,6 +199,7 @@ func loadTestCredits(miner *rpctest.Harness, w *lnwallet.LightningWallet,
 
 	// Wait until the wallet has finished syncing up to the main chain.
 	ticker := time.NewTicker(100 * time.Millisecond)
+	timeout := time.After(30 * time.Second)
 
 	for range ticker.C {
 		balance, err := w.ConfirmedBalance(1, false)
@@ -197,6 +209,17 @@ func loadTestCredits(miner *rpctest.Harness, w *lnwallet.LightningWallet,
 		if balance == expectedBalance {
 			break
 		}
+		select {
+		case <-timeout:
+			synced, err := w.IsSynced()
+			if err != nil {
+				return err
+			}
+			return fmt.Errorf("timed out after 30 seconds "+
+				"waiting for balance %v, current balance %v, "+
+				"synced: %t", expectedBalance, balance, synced)
+		default:
+		}
 	}
 	ticker.Stop()
 
@@ -222,7 +245,7 @@ func createTestWallet(tempTestDir string, miningNode *rpctest.Harness,
 		WalletController: wc,
 		Signer:           signer,
 		ChainIO:          bio,
-		FeeEstimator:     lnwallet.StaticFeeEstimator{FeeRate: 250},
+		FeeEstimator:     lnwallet.StaticFeeEstimator{FeeRate: 10},
 		DefaultConstraints: channeldb.ChannelConstraints{
 			DustLimit:        500,
 			MaxPendingAmount: lnwire.NewMSatFromSatoshis(btcutil.SatoshiPerBitcoin) * 100,
@@ -343,6 +366,9 @@ func testDualFundingReservationWorkflow(miner *rpctest.Harness,
 		bobFundingSigs, bobCommitSig,
 	)
 	if err != nil {
+		for _, in := range aliceChanReservation.FinalFundingTx().TxIn {
+			fmt.Println(in.PreviousOutPoint.String())
+		}
 		t.Fatalf("unable to consume alice's sigs: %v", err)
 	}
 	_, err = bobChanReservation.CompleteReservation(
@@ -384,6 +410,10 @@ func testDualFundingReservationWorkflow(miner *rpctest.Harness,
 
 	// Mine a single block, the funding transaction should be included
 	// within this block.
+	err = waitForMempoolTx(miner, &fundingSha)
+	if err != nil {
+		t.Fatalf("tx not relayed to miner: %v", err)
+	}
 	blockHashes, err := miner.Node.Generate(1)
 	if err != nil {
 		t.Fatalf("unable to generate block: %v", err)
@@ -402,6 +432,16 @@ func testDualFundingReservationWorkflow(miner *rpctest.Harness,
 
 	assertReservationDeleted(aliceChanReservation, t)
 	assertReservationDeleted(bobChanReservation, t)
+
+	// Wait for wallets to catch up to prevent issues in subsequent tests.
+	err = waitForWalletSync(miner, alice)
+	if err != nil {
+		t.Fatalf("unable to sync alice: %v", err)
+	}
+	err = waitForWalletSync(miner, bob)
+	if err != nil {
+		t.Fatalf("unable to sync bob: %v", err)
+	}
 }
 
 func testFundingTransactionLockedOutputs(miner *rpctest.Harness,
@@ -759,6 +799,10 @@ func testSingleFunderReservationWorkflow(miner *rpctest.Harness,
 
 	// Mine a single block, the funding transaction should be included
 	// within this block.
+	err = waitForMempoolTx(miner, &fundingSha)
+	if err != nil {
+		t.Fatalf("tx not relayed to miner: %v", err)
+	}
 	blockHashes, err := miner.Node.Generate(1)
 	if err != nil {
 		t.Fatalf("unable to generate block: %v", err)
@@ -768,7 +812,8 @@ func testSingleFunderReservationWorkflow(miner *rpctest.Harness,
 		t.Fatalf("unable to find block: %v", err)
 	}
 	if len(block.Transactions) != 2 {
-		t.Fatalf("funding transaction wasn't mined: %v", err)
+		t.Fatalf("funding transaction wasn't mined: %d",
+			len(block.Transactions))
 	}
 	blockTx := block.Transactions[1]
 	if blockTx.TxHash() != fundingSha {
@@ -815,8 +860,10 @@ func testListTransactionDetails(miner *rpctest.Harness,
 	}
 
 	// Next, fetch all the current transaction details.
-	// TODO(roasbeef): use ntfn client here instead?
-	time.Sleep(time.Second * 2)
+	err = waitForWalletSync(miner, alice)
+	if err != nil {
+		t.Fatalf("Couldn't sync Alice's wallet: %v", err)
+	}
 	txDetails, err := alice.ListTransactionDetails()
 	if err != nil {
 		t.Fatalf("unable to fetch tx details: %v", err)
@@ -905,6 +952,10 @@ func testListTransactionDetails(miner *rpctest.Harness,
 	if err != nil {
 		t.Fatalf("unable to create burn tx: %v", err)
 	}
+	err = waitForMempoolTx(miner, burnTXID)
+	if err != nil {
+		t.Fatalf("tx not relayed to miner: %v", err)
+	}
 	burnBlock, err := miner.Node.Generate(1)
 	if err != nil {
 		t.Fatalf("unable to mine block: %v", err)
@@ -912,7 +963,10 @@ func testListTransactionDetails(miner *rpctest.Harness,
 
 	// Fetch the transaction details again, the new transaction should be
 	// shown as debiting from the wallet's balance.
-	time.Sleep(time.Second * 2)
+	err = waitForWalletSync(miner, alice)
+	if err != nil {
+		t.Fatalf("Couldn't sync Alice's wallet: %v", err)
+	}
 	txDetails, err = alice.ListTransactionDetails()
 	if err != nil {
 		t.Fatalf("unable to fetch tx details: %v", err)
@@ -955,7 +1009,7 @@ func testTransactionSubscriptions(miner *rpctest.Harness,
 	// implementation of the WalletController.
 	txClient, err := alice.SubscribeTransactions()
 	if err != nil {
-		t.Fatalf("unable to generate tx subscription: %v", err)
+		t.Skipf("unable to generate tx subscription: %v", err)
 	}
 	defer txClient.Cancel()
 
@@ -964,25 +1018,33 @@ func testTransactionSubscriptions(miner *rpctest.Harness,
 		numTxns   = 3
 	)
 	unconfirmedNtfns := make(chan struct{})
-	go func() {
-		for i := 0; i < numTxns; i++ {
-			txDetail := <-txClient.UnconfirmedTransactions()
-			if txDetail.NumConfirmations != 0 {
-				t.Fatalf("incorrect number of confs, expected %v got %v",
-					0, txDetail.NumConfirmations)
+	switch alice.BackEnd() {
+	case "neutrino":
+		// Neutrino doesn't listen for unconfirmed transactions.
+	default:
+		go func() {
+			for i := 0; i < numTxns; i++ {
+				txDetail := <-txClient.UnconfirmedTransactions()
+				if txDetail.NumConfirmations != 0 {
+					t.Fatalf("incorrect number of confs, "+
+						"expected %v got %v", 0,
+						txDetail.NumConfirmations)
+				}
+				if txDetail.Value != outputAmt {
+					t.Fatalf("incorrect output amt, "+
+						"expected %v got %v", outputAmt,
+						txDetail.Value)
+				}
+				if txDetail.BlockHash != nil {
+					t.Fatalf("block hash should be nil, "+
+						"is instead %v",
+						txDetail.BlockHash)
+				}
 			}
-			if txDetail.Value != outputAmt {
-				t.Fatalf("incorrect output amt, expected %v got %v",
-					outputAmt, txDetail.Value)
-			}
-			if txDetail.BlockHash != nil {
-				t.Fatalf("block hash should be nil, is instead %v",
-					txDetail.BlockHash)
-			}
-		}
 
-		close(unconfirmedNtfns)
-	}()
+			close(unconfirmedNtfns)
+		}()
+	}
 
 	// Next, fetch a fresh address from the wallet, create 3 new outputs
 	// with the pkScript.
@@ -1000,17 +1062,27 @@ func testTransactionSubscriptions(miner *rpctest.Harness,
 			Value:    outputAmt,
 			PkScript: script,
 		}
-		if _, err := miner.SendOutputs([]*wire.TxOut{output}, 10); err != nil {
+		txid, err := miner.SendOutputs([]*wire.TxOut{output}, 10)
+		if err != nil {
 			t.Fatalf("unable to send coinbase: %v", err)
 		}
+		err = waitForMempoolTx(miner, txid)
+		if err != nil {
+			t.Fatalf("tx not relayed to miner: %v", err)
+		}
 	}
 
-	// We should receive a notification for all three transactions
-	// generated above.
-	select {
-	case <-time.After(time.Second * 5):
-		t.Fatalf("transactions not received after 3 seconds")
-	case <-unconfirmedNtfns: // Fall through on successs
+	switch alice.BackEnd() {
+	case "neutrino":
+		// Neutrino doesn't listen for on unconfirmed transactions.
+	default:
+		// We should receive a notification for all three transactions
+		// generated above.
+		select {
+		case <-time.After(time.Second * 10):
+			t.Fatalf("transactions not received after 10 seconds")
+		case <-unconfirmedNtfns: // Fall through on successs
+		}
 	}
 
 	confirmedNtfns := make(chan struct{})
@@ -1018,12 +1090,12 @@ func testTransactionSubscriptions(miner *rpctest.Harness,
 		for i := 0; i < numTxns; i++ {
 			txDetail := <-txClient.ConfirmedTransactions()
 			if txDetail.NumConfirmations != 1 {
-				t.Fatalf("incorrect number of confs, expected %v got %v",
-					1, txDetail.NumConfirmations)
+				t.Fatalf("incorrect number of confs for %s, expected %v got %v",
+					txDetail.Hash, 1, txDetail.NumConfirmations)
 			}
 			if txDetail.Value != outputAmt {
-				t.Fatalf("incorrect output amt, expected %v got %v",
-					outputAmt, txDetail.Value)
+				t.Fatalf("incorrect output amt, expected %v got %v in txid %s",
+					outputAmt, txDetail.Value, txDetail.Hash)
 			}
 		}
 		close(confirmedNtfns)
@@ -1039,7 +1111,7 @@ func testTransactionSubscriptions(miner *rpctest.Harness,
 	// since they should be mined in the next block.
 	select {
 	case <-time.After(time.Second * 5):
-		t.Fatalf("transactions not received after 3 seconds")
+		t.Fatalf("transactions not received after 5 seconds")
 	case <-confirmedNtfns: // Fall through on success
 	}
 }
@@ -1088,7 +1160,7 @@ func testSignOutputUsingTweaks(r *rpctest.Harness,
 		// generate a regular p2wkh from that.
 		pubkeyHash := btcutil.Hash160(tweakedKey.SerializeCompressed())
 		keyAddr, err := btcutil.NewAddressWitnessPubKeyHash(pubkeyHash,
-			&chaincfg.SimNetParams)
+			&chaincfg.RegressionNetParams)
 		if err != nil {
 			t.Fatalf("unable to create addr: %v", err)
 		}
@@ -1110,6 +1182,10 @@ func testSignOutputUsingTweaks(r *rpctest.Harness,
 
 		// Query for the transaction generated above so we can located
 		// the index of our output.
+		err = waitForMempoolTx(r, txid)
+		if err != nil {
+			t.Fatalf("tx not relayed to miner: %v", err)
+		}
 		tx, err := r.Node.GetRawTransaction(txid)
 		if err != nil {
 			t.Fatalf("unable to query for tx: %v", err)
@@ -1197,7 +1273,7 @@ func testReorgWalletBalance(r *rpctest.Harness, w *lnwallet.LightningWallet,
 	}
 
 	// Give wallet time to catch up.
-	err = waitForWalletSync(w)
+	err = waitForWalletSync(r, w)
 	if err != nil {
 		t.Fatalf("unable to sync wallet: %v", err)
 	}
@@ -1222,16 +1298,21 @@ func testReorgWalletBalance(r *rpctest.Harness, w *lnwallet.LightningWallet,
 		Value:    1e8,
 		PkScript: script,
 	}
-	if _, err = w.SendOutputs([]*wire.TxOut{output}, 10); err != nil {
+	txid, err := w.SendOutputs([]*wire.TxOut{output}, 10)
+	if err != nil {
 		t.Fatalf("unable to send outputs: %v", err)
 	}
+	err = waitForMempoolTx(r, txid)
+	if err != nil {
+		t.Fatalf("tx not relayed to miner: %v", err)
+	}
 	_, err = r.Node.Generate(50)
 	if err != nil {
 		t.Fatalf("unable to generate blocks on passed node: %v", err)
 	}
 
 	// Give wallet time to catch up.
-	err = waitForWalletSync(w)
+	err = waitForWalletSync(r, w)
 	if err != nil {
 		t.Fatalf("unable to sync wallet: %v", err)
 	}
@@ -1277,32 +1358,34 @@ func testReorgWalletBalance(r *rpctest.Harness, w *lnwallet.LightningWallet,
 	// one block on the passed miner and two on the created miner,
 	// connecting them, and waiting for them to sync.
 	for i := 0; i < 5; i++ {
-		peers, err := r2.Node.GetPeerInfo()
-		if err != nil {
-			t.Fatalf("unable to get peer info: %v", err)
-		}
-		numPeers := len(peers)
-		err = r2.Node.AddNode(r.P2PAddress(), rpcclient.ANRemove)
-		if err != nil {
-			t.Fatalf("unable to disconnect mining nodes: %v", err)
-		}
 		// Wait for disconnection
 		timeout := time.After(30 * time.Second)
-		for true {
+		stillConnected := true
+		var peers []btcjson.GetPeerInfoResult
+		for stillConnected {
 			// Allow for timeout
+			time.Sleep(100 * time.Millisecond)
 			select {
 			case <-timeout:
 				t.Fatalf("timeout waiting for miner disconnect")
 			default:
 			}
+			err = r2.Node.AddNode(r.P2PAddress(), rpcclient.ANRemove)
+			if err != nil {
+				t.Fatalf("unable to disconnect mining nodes: %v",
+					err)
+			}
 			peers, err = r2.Node.GetPeerInfo()
 			if err != nil {
 				t.Fatalf("unable to get peer info: %v", err)
 			}
-			if len(peers) < numPeers {
-				break
+			stillConnected = false
+			for _, peer := range peers {
+				if peer.Addr == r.P2PAddress() {
+					stillConnected = true
+					break
+				}
 			}
-			time.Sleep(100 * time.Millisecond)
 		}
 		_, err = r.Node.Generate(2)
 		if err != nil {
@@ -1318,8 +1401,16 @@ func testReorgWalletBalance(r *rpctest.Harness, w *lnwallet.LightningWallet,
 		// Step 5: Reconnect the miners and wait for them to synchronize.
 		err = r2.Node.AddNode(r.P2PAddress(), rpcclient.ANAdd)
 		if err != nil {
-			t.Fatalf("unable to connect mining nodes together: %v",
-				err)
+			switch err := err.(type) {
+			case *btcjson.RPCError:
+				if err.Code != -8 {
+					t.Fatalf("unable to connect mining "+
+						"nodes together: %v", err)
+				}
+			default:
+				t.Fatalf("unable to connect mining nodes "+
+					"together: %v", err)
+			}
 		}
 		err = rpctest.JoinNodes([]*rpctest.Harness{r2, r},
 			rpctest.Blocks)
@@ -1328,7 +1419,7 @@ func testReorgWalletBalance(r *rpctest.Harness, w *lnwallet.LightningWallet,
 		}
 
 		// Give wallet time to catch up.
-		err = waitForWalletSync(w)
+		err = waitForWalletSync(r, w)
 		if err != nil {
 			t.Fatalf("unable to sync wallet: %v", err)
 		}
@@ -1405,21 +1496,78 @@ func clearWalletStates(a, b *lnwallet.LightningWallet) error {
 	return b.Cfg.Database.Wipe()
 }
 
-func waitForWalletSync(w *lnwallet.LightningWallet) error {
-	var synced bool
+func waitForMempoolTx(r *rpctest.Harness, txid *chainhash.Hash) error {
+	var found bool
+	var tx *btcutil.Tx
 	var err error
 	timeout := time.After(10 * time.Second)
-	for !synced {
-		synced, err = w.IsSynced()
-		if err != nil {
-			return err
-		}
+	for !found {
+		// Do a short wait
 		select {
 		case <-timeout:
 			return fmt.Errorf("timeout after 10s")
 		default:
 		}
 		time.Sleep(100 * time.Millisecond)
+
+		// Check for the harness' knowledge of the txid
+		tx, err = r.Node.GetRawTransaction(txid)
+		if err != nil {
+			switch e := err.(type) {
+			case *btcjson.RPCError:
+				if e.Code == btcjson.ErrRPCNoTxInfo {
+					continue
+				}
+			default:
+			}
+			return err
+		}
+		if tx != nil && tx.MsgTx().TxHash() == *txid {
+			found = true
+		}
+	}
+	return nil
+}
+
+func waitForWalletSync(r *rpctest.Harness, w *lnwallet.LightningWallet) error {
+	var synced bool
+	var err error
+	var bestHash, knownHash *chainhash.Hash
+	var bestHeight, knownHeight int32
+	timeout := time.After(10 * time.Second)
+	for !synced {
+		// Do a short wait
+		select {
+		case <-timeout:
+			return fmt.Errorf("timeout after 10s")
+		default:
+		}
+		time.Sleep(100 * time.Millisecond)
+
+		// Check whether the chain source of the wallet is caught up to
+		// the harness it's supposed to be catching up to.
+		bestHash, bestHeight, err = r.Node.GetBestBlock()
+		if err != nil {
+			return err
+		}
+		knownHash, knownHeight, err = w.Cfg.ChainIO.GetBestBlock()
+		if err != nil {
+			return err
+		}
+		if knownHeight != bestHeight {
+			continue
+		}
+		if *knownHash != *bestHash {
+			return fmt.Errorf("hash at height %d doesn't match: "+
+				"expected %s, got %s", bestHeight, bestHash,
+				knownHash)
+		}
+
+		// Check for synchronization.
+		synced, err = w.IsSynced()
+		if err != nil {
+			return err
+		}
 	}
 	return nil
 }
@@ -1454,7 +1602,7 @@ func TestLightningWallet(t *testing.T) {
 	}
 
 	// Next mine enough blocks in order for segwit and the CSV package
-	// soft-fork to activate on SimNet.
+	// soft-fork to activate on RegNet.
 	numBlocks := netParams.MinerConfirmationWindow * 2
 	if _, err := miningNode.Node.Generate(numBlocks); err != nil {
 		t.Fatalf("unable to generate blocks: %v", err)
@@ -1470,6 +1618,22 @@ func TestLightningWallet(t *testing.T) {
 		t.Fatalf("unable to start notifier: %v", err)
 	}
 
+	for _, walletDriver := range lnwallet.RegisteredWallets() {
+		for _, backEnd := range walletDriver.BackEnds() {
+			runTests(t, walletDriver, backEnd, miningNode,
+				rpcConfig, chainNotifier)
+		}
+	}
+}
+
+// runTests runs all of the tests for a single interface implementation and
+// chain back-end combination. This makes it easier to use `defer` as well as
+// factoring out the test logic from the loop which cycles through the
+// interface implementations.
+func runTests(t *testing.T, walletDriver *lnwallet.WalletDriver,
+	backEnd string, miningNode *rpctest.Harness,
+	rpcConfig rpcclient.ConnConfig,
+	chainNotifier *btcdnotify.BtcdNotifier) {
 	var (
 		bio lnwallet.BlockChainIO
 
@@ -1478,107 +1642,230 @@ func TestLightningWallet(t *testing.T) {
 
 		aliceWalletController lnwallet.WalletController
 		bobWalletController   lnwallet.WalletController
+
+		feeEstimator lnwallet.FeeEstimator
 	)
-	for _, walletDriver := range lnwallet.RegisteredWallets() {
-		tempTestDirAlice, err := ioutil.TempDir("", "lnwallet")
-		if err != nil {
-			t.Fatalf("unable to create temp directory: %v", err)
-		}
-		defer os.RemoveAll(tempTestDirAlice)
 
-		tempTestDirBob, err := ioutil.TempDir("", "lnwallet")
-		if err != nil {
-			t.Fatalf("unable to create temp directory: %v", err)
-		}
-		defer os.RemoveAll(tempTestDirBob)
+	tempTestDirAlice, err := ioutil.TempDir("", "lnwallet")
+	if err != nil {
+		t.Fatalf("unable to create temp directory: %v", err)
+	}
+	defer os.RemoveAll(tempTestDirAlice)
 
-		walletType := walletDriver.WalletType
-		switch walletType {
-		case "btcwallet":
-			aliceChainRPC, err := chain.NewRPCClient(netParams,
+	tempTestDirBob, err := ioutil.TempDir("", "lnwallet")
+	if err != nil {
+		t.Fatalf("unable to create temp directory: %v", err)
+	}
+	defer os.RemoveAll(tempTestDirBob)
+
+	walletType := walletDriver.WalletType
+	switch walletType {
+	case "btcwallet":
+		var aliceClient, bobClient chain.Interface
+		switch backEnd {
+		case "btcd":
+			feeEstimator, err = lnwallet.NewBtcdFeeEstimator(
+				rpcConfig, 250)
+			if err != nil {
+				t.Fatalf("unable to create btcd fee estimator: %v",
+					err)
+			}
+			aliceClient, err = chain.NewRPCClient(netParams,
 				rpcConfig.Host, rpcConfig.User, rpcConfig.Pass,
 				rpcConfig.Certificates, false, 20)
 			if err != nil {
 				t.Fatalf("unable to make chain rpc: %v", err)
 			}
-			aliceWalletConfig := &btcwallet.Config{
-				PrivatePass:  []byte("alice-pass"),
-				HdSeed:       aliceHDSeed[:],
-				DataDir:      tempTestDirAlice,
-				NetParams:    netParams,
-				ChainSource:  aliceChainRPC,
-				FeeEstimator: lnwallet.StaticFeeEstimator{FeeRate: 250},
-			}
-			aliceWalletController, err = walletDriver.New(aliceWalletConfig)
-			if err != nil {
-				t.Fatalf("unable to create btcwallet: %v", err)
-			}
-			aliceSigner = aliceWalletController.(*btcwallet.BtcWallet)
-
-			bobChainRPC, err := chain.NewRPCClient(netParams,
+			bobClient, err = chain.NewRPCClient(netParams,
 				rpcConfig.Host, rpcConfig.User, rpcConfig.Pass,
 				rpcConfig.Certificates, false, 20)
 			if err != nil {
 				t.Fatalf("unable to make chain rpc: %v", err)
 			}
-			bobWalletConfig := &btcwallet.Config{
-				PrivatePass:  []byte("bob-pass"),
-				HdSeed:       bobHDSeed[:],
-				DataDir:      tempTestDirBob,
-				NetParams:    netParams,
-				ChainSource:  bobChainRPC,
-				FeeEstimator: lnwallet.StaticFeeEstimator{FeeRate: 250},
-			}
-			bobWalletController, err = walletDriver.New(bobWalletConfig)
+		case "neutrino":
+			feeEstimator = lnwallet.StaticFeeEstimator{FeeRate: 250}
+			// Set some package-level variable to speed up
+			// operation for tests.
+			neutrino.WaitForMoreCFHeaders = time.Millisecond * 100
+			neutrino.BanDuration = time.Millisecond * 100
+			neutrino.QueryTimeout = time.Millisecond * 500
+			neutrino.QueryNumRetries = 2
+			// Start Alice - open a database, start a neutrino
+			// instance, and initialize a btcwallet driver for it.
+			aliceDB, err := walletdb.Create("bdb",
+				tempTestDirAlice+"/neutrino.db")
 			if err != nil {
-				t.Fatalf("unable to create btcwallet: %v", err)
+				t.Fatalf("unable to create DB: %v", err)
+			}
+			defer aliceDB.Close()
+			aliceChain, err := neutrino.NewChainService(
+				neutrino.Config{
+					DataDir:     tempTestDirAlice,
+					Database:    aliceDB,
+					Namespace:   []byte("alice"),
+					ChainParams: *netParams,
+					ConnectPeers: []string{
+						miningNode.P2PAddress(),
+					},
+				},
+			)
+			if err != nil {
+				t.Fatalf("unable to make neutrino: %v", err)
+			}
+			aliceChain.Start()
+			defer aliceChain.Stop()
+			aliceClient = chain.NewNeutrinoClient(aliceChain)
+
+			// Start Bob - open a database, start a neutrino
+			// instance, and initialize a btcwallet driver for it.
+			bobDB, err := walletdb.Create("bdb",
+				tempTestDirBob+"/neutrino.db")
+			if err != nil {
+				t.Fatalf("unable to create DB: %v", err)
+			}
+			defer bobDB.Close()
+			bobChain, err := neutrino.NewChainService(
+				neutrino.Config{
+					DataDir:     tempTestDirBob,
+					Database:    bobDB,
+					Namespace:   []byte("bob"),
+					ChainParams: *netParams,
+					ConnectPeers: []string{
+						miningNode.P2PAddress(),
+					},
+				},
+			)
+			if err != nil {
+				t.Fatalf("unable to make neutrino: %v", err)
+			}
+			bobChain.Start()
+			defer bobChain.Stop()
+			bobClient = chain.NewNeutrinoClient(bobChain)
+		case "bitcoind":
+			feeEstimator, err = lnwallet.NewBitcoindFeeEstimator(
+				rpcConfig, 250)
+			if err != nil {
+				t.Fatalf("unable to create bitcoind fee estimator: %v",
+					err)
+			}
+			// Start a bitcoind instance.
+			tempBitcoindDir, err := ioutil.TempDir("", "bitcoind")
+			if err != nil {
+				t.Fatalf("unable to create temp directory: %v", err)
+			}
+			zmqPath := "ipc:///" + tempBitcoindDir + "/weks.socket"
+			defer os.RemoveAll(tempBitcoindDir)
+			rpcPort := rand.Int()%(65536-1024) + 1024
+			bitcoind := exec.Command(
+				"bitcoind",
+				"-datadir="+tempBitcoindDir,
+				"-regtest",
+				"-connect="+miningNode.P2PAddress(),
+				"-txindex",
+				"-rpcauth=weks:469e9bb14ab2360f8e226efed5ca6f"+
+					"d$507c670e800a95284294edb5773b05544b"+
+					"220110063096c221be9933c82d38e1",
+				fmt.Sprintf("-rpcport=%d", rpcPort),
+				"-disablewallet",
+				"-zmqpubrawblock="+zmqPath,
+				"-zmqpubrawtx="+zmqPath,
+			)
+			err = bitcoind.Start()
+			if err != nil {
+				t.Fatalf("couldn't start bitcoind: %v", err)
+			}
+			defer bitcoind.Wait()
+			defer bitcoind.Process.Kill()
+
+			// Start an Alice btcwallet bitcoind back end instance.
+			aliceClient, err = chain.NewBitcoindClient(netParams,
+				fmt.Sprintf("127.0.0.1:%d", rpcPort), "weks",
+				"weks", zmqPath, 100*time.Millisecond)
+			if err != nil {
+				t.Fatalf("couldn't start alice client: %v", err)
+			}
+
+			// Start a Bob btcwallet bitcoind back end instance.
+			bobClient, err = chain.NewBitcoindClient(netParams,
+				fmt.Sprintf("127.0.0.1:%d", rpcPort), "weks",
+				"weks", zmqPath, 100*time.Millisecond)
+			if err != nil {
+				t.Fatalf("couldn't start bob client: %v", err)
 			}
-			bobSigner = bobWalletController.(*btcwallet.BtcWallet)
-			bio = bobWalletController.(*btcwallet.BtcWallet)
 		default:
-			// TODO(roasbeef): add neutrino case
-			t.Fatalf("unknown wallet driver: %v", walletType)
+			t.Fatalf("unknown chain driver: %v", backEnd)
 		}
 
-		// Funding via 20 outputs with 4BTC each.
-		alice, err := createTestWallet(tempTestDirAlice, miningNode,
-			netParams, chainNotifier, aliceWalletController,
-			aliceSigner, bio)
+		aliceWalletConfig := &btcwallet.Config{
+			PrivatePass:  []byte("alice-pass"),
+			HdSeed:       aliceHDSeed[:],
+			DataDir:      tempTestDirAlice,
+			NetParams:    netParams,
+			ChainSource:  aliceClient,
+			FeeEstimator: feeEstimator,
+		}
+		aliceWalletController, err = walletDriver.New(aliceWalletConfig)
 		if err != nil {
-			t.Fatalf("unable to create test ln wallet: %v", err)
+			t.Fatalf("unable to create btcwallet: %v", err)
 		}
-		defer alice.Shutdown()
+		aliceSigner = aliceWalletController.(*btcwallet.BtcWallet)
 
-		bob, err := createTestWallet(tempTestDirBob, miningNode,
-			netParams, chainNotifier, bobWalletController,
-			bobSigner, bio)
+		bobWalletConfig := &btcwallet.Config{
+			PrivatePass:  []byte("bob-pass"),
+			HdSeed:       bobHDSeed[:],
+			DataDir:      tempTestDirBob,
+			NetParams:    netParams,
+			ChainSource:  bobClient,
+			FeeEstimator: feeEstimator,
+		}
+		bobWalletController, err = walletDriver.New(bobWalletConfig)
 		if err != nil {
-			t.Fatalf("unable to create test ln wallet: %v", err)
+			t.Fatalf("unable to create btcwallet: %v", err)
 		}
-		defer bob.Shutdown()
+		bobSigner = bobWalletController.(*btcwallet.BtcWallet)
+		bio = bobWalletController.(*btcwallet.BtcWallet)
+	default:
+		t.Fatalf("unknown wallet driver: %v", walletType)
+	}
 
-		// Both wallets should now have 80BTC available for spending.
-		assertProperBalance(t, alice, 1, 80)
-		assertProperBalance(t, bob, 1, 80)
+	// Funding via 20 outputs with 4BTC each.
+	alice, err := createTestWallet(tempTestDirAlice, miningNode, netParams,
+		chainNotifier, aliceWalletController, aliceSigner, bio)
+	if err != nil {
+		t.Fatalf("unable to create test ln wallet: %v", err)
+	}
+	defer alice.Shutdown()
 
-		// Execute every test, clearing possibly mutated wallet state
-		// after each step.
-		for _, walletTest := range walletTests {
-			testName := fmt.Sprintf("%v:%v", walletType,
-				walletTest.name)
-			success := t.Run(testName, func(t *testing.T) {
-				walletTest.test(miningNode, alice, bob, t)
-			})
-			if !success {
-				break
-			}
+	bob, err := createTestWallet(tempTestDirBob, miningNode, netParams,
+		chainNotifier, bobWalletController, bobSigner, bio)
+	if err != nil {
+		t.Fatalf("unable to create test ln wallet: %v", err)
+	}
+	defer bob.Shutdown()
 
-			// TODO(roasbeef): possible reset mining node's
-			// chainstate to initial level, cleanly wipe buckets
-			if err := clearWalletStates(alice, bob); err != nil &&
-				err != bolt.ErrBucketNotFound {
-				t.Fatalf("unable to wipe wallet state: %v", err)
-			}
+	// Both wallets should now have 80BTC available for
+	// spending.
+	assertProperBalance(t, alice, 1, 80)
+	assertProperBalance(t, bob, 1, 80)
+
+	// Execute every test, clearing possibly mutated
+	// wallet state after each step.
+	for _, walletTest := range walletTests {
+		testName := fmt.Sprintf("%v/%v:%v", walletType, backEnd,
+			walletTest.name)
+		success := t.Run(testName, func(t *testing.T) {
+			walletTest.test(miningNode, alice, bob, t)
+		})
+		if !success {
+			break
+		}
+
+		// TODO(roasbeef): possible reset mining
+		// node's chainstate to initial level, cleanly
+		// wipe buckets
+		if err := clearWalletStates(alice, bob); err !=
+			nil && err != bolt.ErrBucketNotFound {
+			t.Fatalf("unable to wipe wallet state: %v", err)
 		}
 	}
 }

routing/chainview/bitcoind.go

@@ -0,0 +1,460 @@
+package chainview
+
+import (
+	"bytes"
+	"encoding/hex"
+	"fmt"
+	"sync"
+	"sync/atomic"
+	"time"
+
+	"github.com/roasbeef/btcd/btcjson"
+	"github.com/roasbeef/btcd/chaincfg"
+	"github.com/roasbeef/btcd/chaincfg/chainhash"
+	"github.com/roasbeef/btcd/rpcclient"
+	"github.com/roasbeef/btcd/wire"
+	"github.com/roasbeef/btcutil"
+	"github.com/roasbeef/btcwallet/chain"
+	"github.com/roasbeef/btcwallet/wtxmgr"
+)
+
+// BitcoindFilteredChainView is an implementation of the FilteredChainView
+// interface which is backed by bitcoind.
+type BitcoindFilteredChainView struct {
+	started int32
+	stopped int32
+
+	// bestHeight is the height of the latest block added to the
+	// blockQueue from the onFilteredConnectedMethod. It is used to
+	// determine up to what height we would need to rescan in case
+	// of a filter update.
+	bestHeightMtx sync.Mutex
+	bestHeight    uint32
+
+	// TODO: Factor out common logic between bitcoind and btcd into a
+	// NodeFilteredView interface.
+	chainClient *chain.BitcoindClient
+
+	// blockEventQueue is the ordered queue used to keep the order
+	// of connected and disconnected blocks sent to the reader of the
+	// chainView.
+	blockQueue *blockEventQueue
+
+	// filterUpdates is a channel in which updates to the utxo filter
+	// attached to this instance are sent over.
+	filterUpdates chan filterUpdate
+
+	// chainFilter is the set of utox's that we're currently watching
+	// spends for within the chain.
+	filterMtx   sync.RWMutex
+	chainFilter map[wire.OutPoint]struct{}
+
+	// filterBlockReqs is a channel in which requests to filter select
+	// blocks will be sent over.
+	filterBlockReqs chan *filterBlockReq
+
+	quit chan struct{}
+	wg   sync.WaitGroup
+}
+
+// A compile time check to ensure BitcoindFilteredChainView implements the
+// chainview.FilteredChainView.
+var _ FilteredChainView = (*BitcoindFilteredChainView)(nil)
+
+// NewBitcoindFilteredChainView creates a new instance of a FilteredChainView
+// from RPC credentials and a ZMQ socket address for a bitcoind instance.
+func NewBitcoindFilteredChainView(config rpcclient.ConnConfig,
+	zmqConnect string, params chaincfg.Params) (*BitcoindFilteredChainView,
+	error) {
+	chainView := &BitcoindFilteredChainView{
+		chainFilter:     make(map[wire.OutPoint]struct{}),
+		filterUpdates:   make(chan filterUpdate),
+		filterBlockReqs: make(chan *filterBlockReq),
+		quit:            make(chan struct{}),
+	}
+
+	chainConn, err := chain.NewBitcoindClient(&params, config.Host,
+		config.User, config.Pass, zmqConnect, 100*time.Millisecond)
+	if err != nil {
+		return nil, err
+	}
+	chainView.chainClient = chainConn
+
+	chainView.blockQueue = newBlockEventQueue()
+
+	return chainView, nil
+}
+
+// Start starts all goroutines necessary for normal operation.
+//
+// NOTE: This is part of the FilteredChainView interface.
+func (b *BitcoindFilteredChainView) Start() error {
+	// Already started?
+	if atomic.AddInt32(&b.started, 1) != 1 {
+		return nil
+	}
+
+	log.Infof("FilteredChainView starting")
+
+	err := b.chainClient.Start()
+	if err != nil {
+		return err
+	}
+
+	_, bestHeight, err := b.chainClient.GetBestBlock()
+	if err != nil {
+		return err
+	}
+
+	b.bestHeightMtx.Lock()
+	b.bestHeight = uint32(bestHeight)
+	b.bestHeightMtx.Unlock()
+
+	b.blockQueue.Start()
+
+	b.wg.Add(1)
+	go b.chainFilterer()
+
+	return nil
+}
+
+// Stop stops all goroutines which we launched by the prior call to the Start
+// method.
+//
+// NOTE: This is part of the FilteredChainView interface.
+func (b *BitcoindFilteredChainView) Stop() error {
+	// Already shutting down?
+	if atomic.AddInt32(&b.stopped, 1) != 1 {
+		return nil
+	}
+
+	// Shutdown the rpc client, this gracefully disconnects from bitcoind's
+	// zmq socket, and cleans up all related resources.
+	b.chainClient.Stop()
+
+	b.blockQueue.Stop()
+
+	log.Infof("FilteredChainView stopping")
+
+	close(b.quit)
+	b.wg.Wait()
+
+	return nil
+}
+
+// onFilteredBlockConnected is called for each block that's connected to the
+// end of the main chain. Based on our current chain filter, the block may or
+// may not include any relevant transactions.
+func (b *BitcoindFilteredChainView) onFilteredBlockConnected(height int32,
+	hash chainhash.Hash, txns []*wtxmgr.TxRecord) {
+
+	mtxs := make([]*wire.MsgTx, len(txns))
+	for i, tx := range txns {
+		mtxs[i] = &tx.MsgTx
+
+		for _, txIn := range mtxs[i].TxIn {
+			// We can delete this outpoint from the chainFilter, as
+			// we just received a block where it was spent. In case
+			// of a reorg, this outpoint might get "un-spent", but
+			// that's okay since it would never be wise to consider
+			// the channel open again (since a spending transaction
+			// exists on the network).
+			b.filterMtx.Lock()
+			delete(b.chainFilter, txIn.PreviousOutPoint)
+			b.filterMtx.Unlock()
+		}
+
+	}
+
+	// We record the height of the last connected block added to the
+	// blockQueue such that we can scan up to this height in case of
+	// a rescan. It must be protected by a mutex since a filter update
+	// might be trying to read it concurrently.
+	b.bestHeightMtx.Lock()
+	b.bestHeight = uint32(height)
+	b.bestHeightMtx.Unlock()
+
+	block := &FilteredBlock{
+		Hash:         hash,
+		Height:       uint32(height),
+		Transactions: mtxs,
+	}
+
+	b.blockQueue.Add(&blockEvent{
+		eventType: connected,
+		block:     block,
+	})
+}
+
+// onFilteredBlockDisconnected is a callback which is executed once a block is
+// disconnected from the end of the main chain.
+func (b *BitcoindFilteredChainView) onFilteredBlockDisconnected(height int32,
+	hash chainhash.Hash) {
+
+	log.Debugf("got disconnected block at height %d: %v", height,
+		hash)
+
+	filteredBlock := &FilteredBlock{
+		Hash:   hash,
+		Height: uint32(height),
+	}
+
+	b.blockQueue.Add(&blockEvent{
+		eventType: disconnected,
+		block:     filteredBlock,
+	})
+}
+
+// FilterBlock takes a block hash, and returns a FilteredBlocks which is the
+// result of applying the current registered UTXO sub-set on the block
+// corresponding to that block hash. If any watched UTOX's are spent by the
+// selected lock, then the internal chainFilter will also be updated.
+//
+// NOTE: This is part of the FilteredChainView interface.
+func (b *BitcoindFilteredChainView) FilterBlock(blockHash *chainhash.Hash) (*FilteredBlock, error) {
+	req := &filterBlockReq{
+		blockHash: blockHash,
+		resp:      make(chan *FilteredBlock, 1),
+		err:       make(chan error, 1),
+	}
+
+	select {
+	case b.filterBlockReqs <- req:
+	case <-b.quit:
+		return nil, fmt.Errorf("FilteredChainView shutting down")
+	}
+
+	return <-req.resp, <-req.err
+}
+
+// chainFilterer is the primary goroutine which: listens for new blocks coming
+// and dispatches the relevent FilteredBlock notifications, updates the filter
+// due to requests by callers, and finally is able to preform targeted block
+// filtration.
+//
+// TODO(roasbeef): change to use loadfilter RPC's
+func (b *BitcoindFilteredChainView) chainFilterer() {
+	defer b.wg.Done()
+
+	// filterBlock is a helper funciton that scans the given block, and
+	// notes which transactions spend outputs which are currently being
+	// watched. Additionally, the chain filter will also be updated by
+	// removing any spent outputs.
+	filterBlock := func(blk *wire.MsgBlock) []*wire.MsgTx {
+		var filteredTxns []*wire.MsgTx
+		for _, tx := range blk.Transactions {
+			for _, txIn := range tx.TxIn {
+				prevOp := txIn.PreviousOutPoint
+				if _, ok := b.chainFilter[prevOp]; ok {
+					filteredTxns = append(filteredTxns, tx)
+
+					b.filterMtx.Lock()
+					delete(b.chainFilter, prevOp)
+					b.filterMtx.Unlock()
+
+					break
+				}
+			}
+		}
+
+		return filteredTxns
+	}
+
+	decodeJSONBlock := func(block *btcjson.RescannedBlock,
+		height uint32) (*FilteredBlock, error) {
+		hash, err := chainhash.NewHashFromStr(block.Hash)
+		if err != nil {
+			return nil, err
+
+		}
+		txs := make([]*wire.MsgTx, 0, len(block.Transactions))
+		for _, str := range block.Transactions {
+			b, err := hex.DecodeString(str)
+			if err != nil {
+				return nil, err
+			}
+			tx := &wire.MsgTx{}
+			err = tx.Deserialize(bytes.NewReader(b))
+			if err != nil {
+				return nil, err
+			}
+			txs = append(txs, tx)
+		}
+		return &FilteredBlock{
+			Hash:         *hash,
+			Height:       height,
+			Transactions: txs,
+		}, nil
+	}
+
+	for {
+		select {
+		// The caller has just sent an update to the current chain
+		// filter, so we'll apply the update, possibly rewinding our
+		// state partially.
+		case update := <-b.filterUpdates:
+
+			// First, we'll add all the new UTXO's to the set of
+			// watched UTXO's, eliminating any duplicates in the
+			// process.
+			log.Debugf("Updating chain filter with new UTXO's: %v",
+				update.newUtxos)
+			for _, newOp := range update.newUtxos {
+				b.filterMtx.Lock()
+				b.chainFilter[newOp] = struct{}{}
+				b.filterMtx.Unlock()
+			}
+
+			// Apply the new TX filter to the chain client, which
+			// will cause all following notifications from and
+			// calls to it return blocks filtered with the new
+			// filter.
+			b.chainClient.LoadTxFilter(false, []btcutil.Address{},
+				update.newUtxos)
+
+			// All blocks gotten after we loaded the filter will
+			// have the filter applied, but we will need to rescan
+			// the blocks up to the height of the block we last
+			// added to the blockQueue.
+			b.bestHeightMtx.Lock()
+			bestHeight := b.bestHeight
+			b.bestHeightMtx.Unlock()
+
+			// If the update height matches our best known height,
+			// then we don't need to do any rewinding.
+			if update.updateHeight == bestHeight {
+				continue
+			}
+
+			// Otherwise, we'll rewind the state to ensure the
+			// caller doesn't miss any relevant notifications.
+			// Starting from the height _after_ the update height,
+			// we'll walk forwards, rescanning one block at a time
+			// with the chain client applying the newly loaded
+			// filter to each block.
+			for i := update.updateHeight + 1; i < bestHeight+1; i++ {
+				blockHash, err := b.chainClient.GetBlockHash(int64(i))
+				if err != nil {
+					log.Warnf("Unable to get block hash "+
+						"for block at height %d: %v",
+						i, err)
+					continue
+				}
+
+				// To avoid dealing with the case where a reorg
+				// is happening while we rescan, we scan one
+				// block at a time, skipping blocks that might
+				// have gone missing.
+				rescanned, err := b.chainClient.RescanBlocks(
+					[]chainhash.Hash{*blockHash})
+				if err != nil {
+					log.Warnf("Unable to rescan block "+
+						"with hash %v at height %d: %v",
+						blockHash, i, err)
+					continue
+				}
+
+				// If no block was returned from the rescan, it
+				// means no matching transactions were found.
+				if len(rescanned) != 1 {
+					log.Tracef("rescan of block %v at "+
+						"height=%d yielded no "+
+						"transactions", blockHash, i)
+					continue
+				}
+				decoded, err := decodeJSONBlock(
+					&rescanned[0], i)
+				if err != nil {
+					log.Errorf("Unable to decode block: %v",
+						err)
+					continue
+				}
+				b.blockQueue.Add(&blockEvent{
+					eventType: connected,
+					block:     decoded,
+				})
+			}
+
+		// We've received a new request to manually filter a block.
+		case req := <-b.filterBlockReqs:
+			// First we'll fetch the block itself as well as some
+			// additional information including its height.
+			block, err := b.chainClient.GetBlock(req.blockHash)
+			if err != nil {
+				req.err <- err
+				req.resp <- nil
+				continue
+			}
+			header, err := b.chainClient.GetBlockHeaderVerbose(
+				req.blockHash)
+			if err != nil {
+				req.err <- err
+				req.resp <- nil
+				continue
+			}
+
+			// Once we have this info, we can directly filter the
+			// block and dispatch the proper notification.
+			req.resp <- &FilteredBlock{
+				Hash:         *req.blockHash,
+				Height:       uint32(header.Height),
+				Transactions: filterBlock(block),
+			}
+			req.err <- err
+
+		// We've received a new event from the chain client.
+		case event := <-b.chainClient.Notifications():
+			switch e := event.(type) {
+			case chain.FilteredBlockConnected:
+				b.onFilteredBlockConnected(e.Block.Height,
+					e.Block.Hash, e.RelevantTxs)
+			case chain.BlockDisconnected:
+				b.onFilteredBlockDisconnected(e.Height, e.Hash)
+			}
+
+		case <-b.quit:
+			return
+		}
+	}
+}
+
+// UpdateFilter updates the UTXO filter which is to be consulted when creating
+// FilteredBlocks to be sent to subscribed clients. This method is cumulative
+// meaning repeated calls to this method should _expand_ the size of the UTXO
+// sub-set currently being watched.  If the set updateHeight is _lower_ than
+// the best known height of the implementation, then the state should be
+// rewound to ensure all relevant notifications are dispatched.
+//
+// NOTE: This is part of the FilteredChainView interface.
+func (b *BitcoindFilteredChainView) UpdateFilter(ops []wire.OutPoint, updateHeight uint32) error {
+	select {
+
+	case b.filterUpdates <- filterUpdate{
+		newUtxos:     ops,
+		updateHeight: updateHeight,
+	}:
+		return nil
+
+	case <-b.quit:
+		return fmt.Errorf("chain filter shutting down")
+	}
+}
+
+// FilteredBlocks returns the channel that filtered blocks are to be sent over.
+// Each time a block is connected to the end of a main chain, and appropriate
+// FilteredBlock which contains the transactions which mutate our watched UTXO
+// set is to be returned.
+//
+// NOTE: This is part of the FilteredChainView interface.
+func (b *BitcoindFilteredChainView) FilteredBlocks() <-chan *FilteredBlock {
+	return b.blockQueue.newBlocks
+}
+
+// DisconnectedBlocks returns a receive only channel which will be sent upon
+// with the empty filtered blocks of blocks which are disconnected from the
+// main chain in the case of a re-org.
+//
+// NOTE: This is part of the FilteredChainView interface.
+func (b *BitcoindFilteredChainView) DisconnectedBlocks() <-chan *FilteredBlock {
+	return b.blockQueue.staleBlocks
+}

routing/chainview/interface_test.go

@@ -4,13 +4,16 @@ import (
 	"bytes"
 	"fmt"
 	"io/ioutil"
+	"math/rand"
 	"os"
+	"os/exec"
 	"path/filepath"
 	"runtime"
 	"testing"
 	"time"
 
 	"github.com/lightninglabs/neutrino"
+	"github.com/ltcsuite/ltcd/btcjson"
 	"github.com/roasbeef/btcd/btcec"
 	"github.com/roasbeef/btcd/chaincfg"
 	"github.com/roasbeef/btcd/chaincfg/chainhash"
@@ -25,7 +28,7 @@ import (
 )
 
 var (
-	netParams = &chaincfg.SimNetParams
+	netParams = &chaincfg.RegressionNetParams
 
 	testPrivKey = []byte{
 		0x81, 0xb6, 0x37, 0xd8, 0xfc, 0xd2, 0xc6, 0xda,
@@ -42,6 +45,39 @@ var (
 	testScript, _ = txscript.PayToAddrScript(testAddr)
 )
 
+func waitForMempoolTx(r *rpctest.Harness, txid *chainhash.Hash) error {
+	var found bool
+	var tx *btcutil.Tx
+	var err error
+	timeout := time.After(10 * time.Second)
+	for !found {
+		// Do a short wait
+		select {
+		case <-timeout:
+			return fmt.Errorf("timeout after 10s")
+		default:
+		}
+		time.Sleep(100 * time.Millisecond)
+
+		// Check for the harness' knowledge of the txid
+		tx, err = r.Node.GetRawTransaction(txid)
+		if err != nil {
+			switch e := err.(type) {
+			case *btcjson.RPCError:
+				if e.Code == btcjson.ErrRPCNoTxInfo {
+					continue
+				}
+			default:
+			}
+			return err
+		}
+		if tx != nil && tx.MsgTx().TxHash() == *txid {
+			found = true
+		}
+	}
+	return nil
+}
+
 func getTestTXID(miner *rpctest.Harness) (*chainhash.Hash, error) {
 	script, err := txscript.PayToAddrScript(testAddr)
 	if err != nil {
@@ -131,11 +167,19 @@ func testFilterBlockNotifications(node *rpctest.Harness,
 	// private key that we generated above.
 	txid1, err := getTestTXID(node)
 	if err != nil {
-		t.Fatalf("unable to get test txid")
+		t.Fatalf("unable to get test txid: %v", err)
+	}
+	err = waitForMempoolTx(node, txid1)
+	if err != nil {
+		t.Fatalf("unable to get test txid in mempool: %v", err)
 	}
 	txid2, err := getTestTXID(node)
 	if err != nil {
-		t.Fatalf("unable to get test txid")
+		t.Fatalf("unable to get test txid: %v", err)
+	}
+	err = waitForMempoolTx(node, txid2)
+	if err != nil {
+		t.Fatalf("unable to get test txid in mempool: %v", err)
 	}
 
 	blockChan := chainView.FilteredBlocks()
@@ -218,6 +262,10 @@ func testFilterBlockNotifications(node *rpctest.Harness,
 	if err != nil {
 		t.Fatalf("unable to broadcast transaction: %v", err)
 	}
+	err = waitForMempoolTx(node, spendTxid1)
+	if err != nil {
+		t.Fatalf("unable to get spending txid in mempool: %v", err)
+	}
 	newBlockHashes, err = node.Node.Generate(1)
 	if err != nil {
 		t.Fatalf("unable to generate block: %v", err)
@@ -240,6 +288,10 @@ func testFilterBlockNotifications(node *rpctest.Harness,
 	if err != nil {
 		t.Fatalf("unable to broadcast transaction: %v", err)
 	}
+	err = waitForMempoolTx(node, spendTxid2)
+	if err != nil {
+		t.Fatalf("unable to get spending txid in mempool: %v", err)
+	}
 	newBlockHashes, err = node.Node.Generate(1)
 	if err != nil {
 		t.Fatalf("unable to generate block: %v", err)
@@ -264,6 +316,10 @@ func testUpdateFilterBackTrack(node *rpctest.Harness,
 	if err != nil {
 		t.Fatalf("unable to get test txid")
 	}
+	err = waitForMempoolTx(node, txid)
+	if err != nil {
+		t.Fatalf("unable to get test txid in mempool: %v", err)
+	}
 
 	// Next we'll mine a block confirming the output generated above.
 	initBlockHashes, err := node.Node.Generate(1)
@@ -306,6 +362,10 @@ func testUpdateFilterBackTrack(node *rpctest.Harness,
 	if err != nil {
 		t.Fatalf("unable to broadcast transaction: %v", err)
 	}
+	err = waitForMempoolTx(node, spendTxid)
+	if err != nil {
+		t.Fatalf("unable to get spending txid in mempool: %v", err)
+	}
 	newBlockHashes, err := node.Node.Generate(1)
 	if err != nil {
 		t.Fatalf("unable to generate block: %v", err)
@@ -352,10 +412,18 @@ func testFilterSingleBlock(node *rpctest.Harness, chainView FilteredChainView,
 	if err != nil {
 		t.Fatalf("unable to get test txid")
 	}
+	err = waitForMempoolTx(node, txid1)
+	if err != nil {
+		t.Fatalf("unable to get test txid in mempool: %v", err)
+	}
 	txid2, err := getTestTXID(node)
 	if err != nil {
 		t.Fatalf("unable to get test txid")
 	}
+	err = waitForMempoolTx(node, txid2)
+	if err != nil {
+		t.Fatalf("unable to get test txid in mempool: %v", err)
+	}
 
 	blockChan := chainView.FilteredBlocks()
 
@@ -671,7 +739,7 @@ var chainViewTests = []testCase{
 		test: testUpdateFilterBackTrack,
 	},
 	{
-		name: "fitler single block",
+		name: "filter single block",
 		test: testFilterSingleBlock,
 	},
 	{
@@ -684,6 +752,68 @@ var interfaceImpls = []struct {
 	name          string
 	chainViewInit chainViewInitFunc
 }{
+	{
+		name: "bitcoind_zmq",
+		chainViewInit: func(_ rpcclient.ConnConfig, p2pAddr string) (func(), FilteredChainView, error) {
+			// Start a bitcoind instance.
+			tempBitcoindDir, err := ioutil.TempDir("", "bitcoind")
+			if err != nil {
+				return nil, nil, err
+			}
+			zmqPath := "ipc:///" + tempBitcoindDir + "/weks.socket"
+			cleanUp1 := func() {
+				os.RemoveAll(tempBitcoindDir)
+			}
+			rpcPort := rand.Int()%(65536-1024) + 1024
+			bitcoind := exec.Command(
+				"bitcoind",
+				"-datadir="+tempBitcoindDir,
+				"-regtest",
+				"-connect="+p2pAddr,
+				"-txindex",
+				"-rpcauth=weks:469e9bb14ab2360f8e226efed5ca6f"+
+					"d$507c670e800a95284294edb5773b05544b"+
+					"220110063096c221be9933c82d38e1",
+				fmt.Sprintf("-rpcport=%d", rpcPort),
+				"-disablewallet",
+				"-zmqpubrawblock="+zmqPath,
+				"-zmqpubrawtx="+zmqPath,
+			)
+			err = bitcoind.Start()
+			if err != nil {
+				cleanUp1()
+				return nil, nil, err
+			}
+			cleanUp2 := func() {
+				bitcoind.Process.Kill()
+				bitcoind.Wait()
+				cleanUp1()
+			}
+
+			// Wait for the bitcoind instance to start up.
+			time.Sleep(time.Second)
+
+			// Start the FilteredChainView implementation instance.
+			config := rpcclient.ConnConfig{
+				Host: fmt.Sprintf(
+					"127.0.0.1:%d", rpcPort),
+				User:                 "weks",
+				Pass:                 "weks",
+				DisableAutoReconnect: false,
+				DisableConnectOnNew:  true,
+				DisableTLS:           true,
+				HTTPPostMode:         true,
+			}
+
+			chainView, err := NewBitcoindFilteredChainView(config,
+				zmqPath, chaincfg.RegressionNetParams)
+			if err != nil {
+				cleanUp2()
+				return nil, nil, err
+			}
+			return cleanUp2, chainView, nil
+		},
+	},
 	{
 		name: "p2p_neutrino",
 		chainViewInit: func(_ rpcclient.ConnConfig, p2pAddr string) (func(), FilteredChainView, error) {