watchtower/wtclient/interface: add DB ifaces

watchtower/wtclient/interface.go

@@ -0,0 +1,76 @@
+package wtclient
+
+import (
+	"net"
+
+	"github.com/btcsuite/btcd/btcec"
+	"github.com/lightningnetwork/lnd/brontide"
+	"github.com/lightningnetwork/lnd/lnwire"
+	"github.com/lightningnetwork/lnd/watchtower/wtdb"
+	"github.com/lightningnetwork/lnd/watchtower/wtserver"
+)
+
+// DB abstracts the required database operations required by the watchtower
+// client.
+type DB interface {
+	// CreateTower initialize an address record used to communicate with a
+	// watchtower. Each Tower is assigned a unique ID, that is used to
+	// amortize storage costs of the public key when used by multiple
+	// sessions.
+	CreateTower(*lnwire.NetAddress) (*wtdb.Tower, error)
+
+	// CreateClientSession saves a newly negotiated client session to the
+	// client's database. This enables the session to be used across
+	// restarts.
+	CreateClientSession(*wtdb.ClientSession) error
+
+	// ListClientSessions returns all sessions that have not yet been
+	// exhausted. This is used on startup to find any sessions which may
+	// 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)
+
+	// AddChanPkScript inserts a newly generated sweep pkscript for the
+	// given channel.
+	AddChanPkScript(lnwire.ChannelID, []byte) error
+
+	// MarkBackupIneligible records that the state identified by the
+	// (channel id, commit height) tuple was ineligible for being backed up
+	// under the current policy. This state can be retried later under a
+	// different policy.
+	MarkBackupIneligible(chanID lnwire.ChannelID, commitHeight uint64) error
+
+	// CommitUpdate writes the next state update for a particular
+	// session, so that we can be sure to resend it after a restart if it
+	// hasn't been ACK'd by the tower. The sequence number of the update
+	// should be exactly one greater than the existing entry, and less that
+	// or equal to the session's MaxUpdates.
+	CommitUpdate(id *wtdb.SessionID, seqNum uint16,
+		update *wtdb.CommittedUpdate) (uint16, error)
+
+	// AckUpdate records an acknowledgment from the watchtower that the
+	// update identified by seqNum was received and saved. The returned
+	// lastApplied will be recorded.
+	AckUpdate(id *wtdb.SessionID, seqNum, lastApplied uint16) error
+}
+
+// Dial connects to an addr using the specified net and returns the connection
+// object.
+type Dial func(net, addr string) (net.Conn, error)
+
+// AuthDialer connects to a remote node using an authenticated transport, such as
+// brontide. The dialer argument is used to specify a resolver, which allows
+// this method to be used over Tor or clear net connections.
+type AuthDialer func(localPriv *btcec.PrivateKey, netAddr *lnwire.NetAddress,
+	dialer func(string, string) (net.Conn, error)) (wtserver.Peer, error)
+
+// AuthDial is the watchtower client's default method of dialing.
+func AuthDial(localPriv *btcec.PrivateKey, netAddr *lnwire.NetAddress,
+	dialer func(string, string) (net.Conn, error)) (wtserver.Peer, error) {
+
+	return brontide.Dial(localPriv, netAddr, dialer)
+}