watchtower: make use of the new AddressIterator

This commit upgrades the wtclient package to make use of the new
`AddressIterator`. It does so by first creating new `Tower` and
`ClientSession` types. The new `Tower` type has an `AddressIterator`
instead of a list of addresses. The `ClientSession` type contains a
`Tower`.

watchtower/wtdb/client_db.go

@@ -429,7 +429,7 @@ func (c *ClientDB) RemoveTower(pubKey *btcec.PublicKey, addr net.Addr) error {
 		}
 
 		towerSessions, err := listTowerSessions(
-			towerID, sessions, towers, towersToSessionsIndex,
+			towerID, sessions, towersToSessionsIndex,
 			WithPerCommittedUpdate(perCommittedUpdate),
 		)
 		if err != nil {
@@ -766,7 +766,7 @@ func (c *ClientDB) ListClientSessions(id *TowerID,
 		// known to the db.
 		if id == nil {
 			clientSessions, err = listClientAllSessions(
-				sessions, towers, opts...,
+				sessions, opts...,
 			)
 			return err
 		}
@@ -778,7 +778,7 @@ func (c *ClientDB) ListClientSessions(id *TowerID,
 		}
 
 		clientSessions, err = listTowerSessions(
-			*id, sessions, towers, towerToSessionIndex, opts...,
+			*id, sessions, towerToSessionIndex, opts...,
 		)
 		return err
 	}, func() {
@@ -792,7 +792,7 @@ func (c *ClientDB) ListClientSessions(id *TowerID,
 }
 
 // listClientAllSessions returns the set of all client sessions known to the db.
-func listClientAllSessions(sessions, towers kvdb.RBucket,
+func listClientAllSessions(sessions kvdb.RBucket,
 	opts ...ClientSessionListOption) (map[SessionID]*ClientSession, error) {
 
 	clientSessions := make(map[SessionID]*ClientSession)
@@ -801,7 +801,7 @@ func listClientAllSessions(sessions, towers kvdb.RBucket,
 		// the CommittedUpdates and AckedUpdates on startup to resume
 		// committed updates and compute the highest known commit height
 		// for each channel.
-		session, err := getClientSession(sessions, towers, k, opts...)
+		session, err := getClientSession(sessions, k, opts...)
 		if err != nil {
 			return err
 		}
@@ -819,7 +819,7 @@ func listClientAllSessions(sessions, towers kvdb.RBucket,
 
 // listTowerSessions returns the set of all client sessions known to the db
 // that are associated with the given tower id.
-func listTowerSessions(id TowerID, sessionsBkt, towersBkt,
+func listTowerSessions(id TowerID, sessionsBkt,
 	towerToSessionIndex kvdb.RBucket, opts ...ClientSessionListOption) (
 	map[SessionID]*ClientSession, error) {
 
@@ -834,9 +834,7 @@ func listTowerSessions(id TowerID, sessionsBkt, towersBkt,
 		// the CommittedUpdates and AckedUpdates on startup to resume
 		// committed updates and compute the highest known commit height
 		// for each channel.
-		session, err := getClientSession(
-			sessionsBkt, towersBkt, k, opts...,
-		)
+		session, err := getClientSession(sessionsBkt, k, opts...)
 		if err != nil {
 			return err
 		}
@@ -1248,7 +1246,7 @@ func WithPerCommittedUpdate(cb PerCommittedUpdateCB) ClientSessionListOption {
 // getClientSession loads the full ClientSession associated with the serialized
 // session id. This method populates the CommittedUpdates, AckUpdates and Tower
 // in addition to the ClientSession's body.
-func getClientSession(sessions, towers kvdb.RBucket, idBytes []byte,
+func getClientSession(sessions kvdb.RBucket, idBytes []byte,
 	opts ...ClientSessionListOption) (*ClientSession, error) {
 
 	cfg := NewClientSessionCfg()
@@ -1261,13 +1259,6 @@ func getClientSession(sessions, towers kvdb.RBucket, idBytes []byte,
 		return nil, err
 	}
 
-	// Fetch the tower associated with this session.
-	tower, err := getTower(towers, session.TowerID.Bytes())
-	if err != nil {
-		return nil, err
-	}
-	session.Tower = tower
-
 	// Can't fail because client session body has already been read.
 	sessionBkt := sessions.NestedReadBucket(idBytes)
 

watchtower/wtdb/client_db_test.go

@@ -343,8 +343,11 @@ func testCreateTower(h *clientDBHarness) {
 	h.loadTowerByID(20, wtdb.ErrTowerNotFound)
 
 	tower := h.newTower()
-	require.Len(h.t, tower.LNAddrs(), 1)
-	towerAddr := tower.LNAddrs()[0]
+	require.Len(h.t, tower.Addresses, 1)
+	towerAddr := &lnwire.NetAddress{
+		IdentityKey: tower.IdentityKey,
+		Address:     tower.Addresses[0],
+	}
 
 	// Load the tower from the database and assert that it matches the tower
 	// we created.

watchtower/wtdb/client_session.go

@@ -4,7 +4,6 @@ import (
 	"fmt"
 	"io"
 
-	"github.com/lightningnetwork/lnd/keychain"
 	"github.com/lightningnetwork/lnd/lnwire"
 	"github.com/lightningnetwork/lnd/watchtower/blob"
 	"github.com/lightningnetwork/lnd/watchtower/wtpolicy"
@@ -36,19 +35,6 @@ type ClientSession struct {
 	ID SessionID
 
 	ClientSessionBody
-
-	// Tower holds the pubkey and address of the watchtower.
-	//
-	// NOTE: This value is not serialized. It is recovered by looking up the
-	// tower with TowerID.
-	Tower *Tower
-
-	// SessionKeyECDH is the ECDH capable wrapper of the ephemeral secret
-	// key used to connect to the watchtower.
-	//
-	// NOTE: This value is not serialized. It is derived using the KeyIndex
-	// on startup to avoid storing private keys on disk.
-	SessionKeyECDH keychain.SingleKeyECDH
 }
 
 // ClientSessionBody represents the primary components of a ClientSession that

watchtower/wtdb/tower.go

@@ -7,7 +7,6 @@ import (
 	"net"
 
 	"github.com/btcsuite/btcd/btcec/v2"
-	"github.com/lightningnetwork/lnd/lnwire"
 )
 
 // TowerID is a unique 64-bit identifier allocated to each unique watchtower.
@@ -77,23 +76,6 @@ func (t *Tower) RemoveAddress(addr net.Addr) {
 	}
 }
 
-// LNAddrs generates a list of lnwire.NetAddress from a Tower instance's
-// addresses. This can be used to have a client try multiple addresses for the
-// same Tower.
-//
-// NOTE: This method is NOT safe for concurrent use.
-func (t *Tower) LNAddrs() []*lnwire.NetAddress {
-	addrs := make([]*lnwire.NetAddress, 0, len(t.Addresses))
-	for _, addr := range t.Addresses {
-		addrs = append(addrs, &lnwire.NetAddress{
-			IdentityKey: t.IdentityKey,
-			Address:     addr,
-		})
-	}
-
-	return addrs
-}
-
 // String returns a user-friendly identifier of the tower.
 func (t *Tower) String() string {
 	pubKey := hex.EncodeToString(t.IdentityKey.SerializeCompressed())