watchtower/wtclient: integrate ClientChannelSummaries

In this commit, we utilize the more generic ClientChanSummary instead of
exposing methods that only allow us to set and fetch sweep pkscripts.

watchtower/wtclient/client.go

@@ -150,8 +150,8 @@ type TowerClient struct {
 	sessionQueue *sessionQueue
 	prevTask     *backupTask
 
-	sweepPkScriptMu sync.RWMutex
-	sweepPkScripts  map[lnwire.ChannelID][]byte
+	summaryMu sync.RWMutex
+	summaries wtdb.ChannelSummaries
 
 	statTicker *time.Ticker
 	stats      clientStats
@@ -245,7 +245,7 @@ func New(config *Config) (*TowerClient, error) {
 
 	// Finally, load the sweep pkscripts that have been generated for all
 	// previously registered channels.
-	c.sweepPkScripts, err = c.cfg.DB.FetchChanPkScripts()
+	c.summaries, err = c.cfg.DB.FetchChanSummaries()
 	if err != nil {
 		return nil, err
 	}
@@ -388,12 +388,12 @@ func (c *TowerClient) ForceQuit() {
 // within the client. This should be called during link startup to ensure that
 // the client is able to support the link during operation.
 func (c *TowerClient) RegisterChannel(chanID lnwire.ChannelID) error {
-	c.sweepPkScriptMu.Lock()
-	defer c.sweepPkScriptMu.Unlock()
+	c.summaryMu.Lock()
+	defer c.summaryMu.Unlock()
 
 	// If a pkscript for this channel already exists, the channel has been
 	// previously registered.
-	if _, ok := c.sweepPkScripts[chanID]; ok {
+	if _, ok := c.summaries[chanID]; ok {
 		return nil
 	}
 
@@ -406,14 +406,16 @@ func (c *TowerClient) RegisterChannel(chanID lnwire.ChannelID) error {
 
 	// Persist the sweep pkscript so that restarts will not introduce
 	// address inflation when the channel is reregistered after a restart.
-	err = c.cfg.DB.AddChanPkScript(chanID, pkScript)
+	err = c.cfg.DB.RegisterChannel(chanID, pkScript)
 	if err != nil {
 		return err
 	}
 
 	// Finally, cache the pkscript in our in-memory cache to avoid db
 	// lookups for the remainder of the daemon's execution.
-	c.sweepPkScripts[chanID] = pkScript
+	c.summaries[chanID] = wtdb.ClientChanSummary{
+		SweepPkScript: pkScript,
+	}
 
 	return nil
 }
@@ -429,14 +431,14 @@ func (c *TowerClient) BackupState(chanID *lnwire.ChannelID,
 	breachInfo *lnwallet.BreachRetribution) error {
 
 	// Retrieve the cached sweep pkscript used for this channel.
-	c.sweepPkScriptMu.RLock()
-	sweepPkScript, ok := c.sweepPkScripts[*chanID]
-	c.sweepPkScriptMu.RUnlock()
+	c.summaryMu.RLock()
+	summary, ok := c.summaries[*chanID]
+	c.summaryMu.RUnlock()
 	if !ok {
 		return ErrUnregisteredChannel
 	}
 
-	task := newBackupTask(chanID, breachInfo, sweepPkScript)
+	task := newBackupTask(chanID, breachInfo, summary.SweepPkScript)
 
 	return c.pipeline.QueueBackupTask(task)
 }

watchtower/wtclient/client_test.go

@@ -605,6 +605,8 @@ func (h *testHarness) backupStates(id, from, to uint64, expErr error) {
 // backupStates instructs the channel identified by id to send a backup for
 // state i.
 func (h *testHarness) backupState(id, i uint64, expErr error) {
+	h.t.Helper()
+
 	_, retribution := h.channel(id).getState(i)
 
 	chanID := chanIDFromInt(id)

watchtower/wtclient/interface.go

@@ -41,14 +41,17 @@ type DB interface {
 	// still be able to accept state updates.
 	ListClientSessions() (map[wtdb.SessionID]*wtdb.ClientSession, error)
 
-	// FetchChanPkScripts returns a map of all sweep pkscripts for
-	// registered channels. This is used on startup to cache the sweep
-	// pkscripts of registered channels in memory.
-	FetchChanPkScripts() (map[lnwire.ChannelID][]byte, error)
+	// FetchChanSummaries loads a mapping from all registered channels to
+	// their channel summaries.
+	FetchChanSummaries() (wtdb.ChannelSummaries, error)
 
-	// AddChanPkScript inserts a newly generated sweep pkscript for the
-	// given channel.
-	AddChanPkScript(lnwire.ChannelID, []byte) error
+	// RegisterChannel registers a channel for use within the client
+	// database. For now, all that is stored in the channel summary is the
+	// sweep pkscript that we'd like any tower sweeps to pay into. In the
+	// future, this will be extended to contain more info to allow the
+	// client efficiently request historical states to be backed up under
+	// the client's active policy.
+	RegisterChannel(lnwire.ChannelID, []byte) error
 
 	// MarkBackupIneligible records that the state identified by the
 	// (channel id, commit height) tuple was ineligible for being backed up

watchtower/wtdb/client_chan_summary.go

@@ -1,11 +1,18 @@
 package wtdb
 
 import (
+	"errors"
 	"io"
 
 	"github.com/lightningnetwork/lnd/lnwire"
 )
 
+var (
+	// ErrChannelAlreadyRegistered signals a duplicate attempt to
+	// register a channel with the client database.
+	ErrChannelAlreadyRegistered = errors.New("channel already registered")
+)
+
 // ChannelSummaries is a map for a given channel id to it's ClientChanSummary.
 type ChannelSummaries map[lnwire.ChannelID]ClientChanSummary
 

watchtower/wtmock/client_db.go

@@ -1,7 +1,6 @@
 package wtmock
 
 import (
-	"fmt"
 	"net"
 	"sync"
 	"sync/atomic"
@@ -18,7 +17,7 @@ type ClientDB struct {
 	nextTowerID uint64 // to be used atomically
 
 	mu             sync.Mutex
-	sweepPkScripts map[lnwire.ChannelID][]byte
+	summaries      map[lnwire.ChannelID]wtdb.ClientChanSummary
 	activeSessions map[wtdb.SessionID]*wtdb.ClientSession
 	towerIndex     map[towerPK]wtdb.TowerID
 	towers         map[wtdb.TowerID]*wtdb.Tower
@@ -30,7 +29,7 @@ type ClientDB struct {
 // NewClientDB initializes a new mock ClientDB.
 func NewClientDB() *ClientDB {
 	return &ClientDB{
-		sweepPkScripts: make(map[lnwire.ChannelID][]byte),
+		summaries:      make(map[lnwire.ChannelID]wtdb.ClientChanSummary),
 		activeSessions: make(map[wtdb.SessionID]*wtdb.ClientSession),
 		towerIndex:     make(map[towerPK]wtdb.TowerID),
 		towers:         make(map[wtdb.TowerID]*wtdb.Tower),
@@ -252,30 +251,40 @@ func (m *ClientDB) AckUpdate(id *wtdb.SessionID, seqNum, lastApplied uint16) err
 	return wtdb.ErrCommittedUpdateNotFound
 }
 
-// FetchChanPkScripts returns the set of sweep pkscripts known for all channels.
-// This allows the client to cache them in memory on startup.
-func (m *ClientDB) FetchChanPkScripts() (map[lnwire.ChannelID][]byte, error) {
+// FetchChanSummaries loads a mapping from all registered channels to their
+// channel summaries.
+func (m *ClientDB) FetchChanSummaries() (wtdb.ChannelSummaries, error) {
 	m.mu.Lock()
 	defer m.mu.Unlock()
 
-	sweepPkScripts := make(map[lnwire.ChannelID][]byte)
-	for chanID, pkScript := range m.sweepPkScripts {
-		sweepPkScripts[chanID] = cloneBytes(pkScript)
+	summaries := make(map[lnwire.ChannelID]wtdb.ClientChanSummary)
+	for chanID, summary := range m.summaries {
+		summaries[chanID] = wtdb.ClientChanSummary{
+			SweepPkScript: cloneBytes(summary.SweepPkScript),
+		}
 	}
 
-	return sweepPkScripts, nil
+	return summaries, nil
 }
 
-// AddChanPkScript sets a pkscript or sweeping funds from the channel or chanID.
-func (m *ClientDB) AddChanPkScript(chanID lnwire.ChannelID, pkScript []byte) error {
+// RegisterChannel registers a channel for use within the client database. For
+// now, all that is stored in the channel summary is the sweep pkscript that
+// we'd like any tower sweeps to pay into. In the future, this will be extended
+// to contain more info to allow the client efficiently request historical
+// states to be backed up under the client's active policy.
+func (m *ClientDB) RegisterChannel(chanID lnwire.ChannelID,
+	sweepPkScript []byte) error {
+
 	m.mu.Lock()
 	defer m.mu.Unlock()
 
-	if _, ok := m.sweepPkScripts[chanID]; ok {
-		return fmt.Errorf("pkscript for %x already exists", pkScript)
+	if _, ok := m.summaries[chanID]; ok {
+		return wtdb.ErrChannelAlreadyRegistered
 	}
 
-	m.sweepPkScripts[chanID] = cloneBytes(pkScript)
+	m.summaries[chanID] = wtdb.ClientChanSummary{
+		SweepPkScript: cloneBytes(sweepPkScript),
+	}
 
 	return nil
 }