peer: make a DaemonAdapter impl for lnd

Similar to the last commit, in this commit, we make a daemon adapter
impl for lnd. We'll use this for any future protofsm based state
machine.

peer/daemon_adapters.go

@@ -0,0 +1,149 @@
+package peer
+
+import (
+	"fmt"
+
+	"github.com/btcsuite/btcd/btcec/v2"
+	"github.com/btcsuite/btcd/chaincfg/chainhash"
+	"github.com/btcsuite/btcd/wire"
+	"github.com/lightningnetwork/lnd/chainntnfs"
+	"github.com/lightningnetwork/lnd/lnwire"
+	"github.com/lightningnetwork/lnd/protofsm"
+)
+
+// MessageSender is an interface that represents an object capable of sending
+// p2p messages to a destination.
+type MessageSender interface {
+	// SendMessages sends the target set of messages to the target peer.
+	//
+	// TODO(roasbeef): current impl bound to single peer, need server
+	// pointer otherwise
+	SendMessages(btcec.PublicKey, []lnwire.Message) error
+}
+
+// flexMessageSender is a message sender-like interface that is aware of
+// sync/async semantics, and is bound to a single peer.
+//
+//nolint:unused
+type flexMessageSender interface {
+	// SendMessage sends a variadic number of high-priority messages to the
+	// remote peer. The first argument denotes if the method should block
+	// until the messages have been sent to the remote peer or an error is
+	// returned, otherwise it returns immediately after queuing.
+	SendMessage(sync bool, msgs ...lnwire.Message) error
+}
+
+// peerMsgSender implements the MessageSender interface for a single peer.
+// It'll return an error if the target public isn't equal to public key of the
+// backing peer.
+//
+//nolint:unused
+type peerMsgSender struct {
+	sender  flexMessageSender
+	peerPub btcec.PublicKey
+}
+
+// newPeerMsgSender creates a new instance of a peerMsgSender.
+//
+//nolint:unused
+func newPeerMsgSender(peerPub btcec.PublicKey,
+	msgSender flexMessageSender) *peerMsgSender {
+
+	return &peerMsgSender{
+		sender:  msgSender,
+		peerPub: peerPub,
+	}
+}
+
+// SendMessages sends the target set of messages to the target peer.
+//
+// TODO(roasbeef): current impl bound to single peer, need server pointer
+// otherwise?
+//
+//nolint:unused
+func (p *peerMsgSender) SendMessages(pub btcec.PublicKey,
+	msgs []lnwire.Message) error {
+
+	if !p.peerPub.IsEqual(&pub) {
+		return fmt.Errorf("wrong peer pubkey: got %x, can only send "+
+			"to %x", pub.SerializeCompressed(),
+			p.peerPub.SerializeCompressed())
+	}
+
+	return p.sender.SendMessage(true, msgs...)
+}
+
+// TxBroadcaster is an interface that represents an object capable of
+// broadcasting transactions to the network.
+type TxBroadcaster interface {
+	// PublishTransaction broadcasts a transaction to the network.
+	PublishTransaction(*wire.MsgTx, string) error
+}
+
+// LndAdapterCfg is a struct that holds the configuration for the
+// LndDaemonAdapters instance.
+type LndAdapterCfg struct {
+	// MsgSender is capable of sending messages to an arbitrary peer.
+	MsgSender MessageSender
+
+	// TxBroadcaster is capable of broadcasting a transaction to the
+	// network.
+	TxBroadcaster TxBroadcaster
+
+	// ChainNotifier is capable of receiving notifications for on-chain
+	// events.
+	ChainNotifier chainntnfs.ChainNotifier
+}
+
+// LndDaemonAdapters is a struct that implements the protofsm.DaemonAdapters
+// interface using common lnd abstractions.
+type LndDaemonAdapters struct {
+	cfg LndAdapterCfg
+}
+
+// NewLndDaemonAdapters creates a new instance of the lndDaemonAdapters struct.
+func NewLndDaemonAdapters(cfg LndAdapterCfg) *LndDaemonAdapters {
+	return &LndDaemonAdapters{
+		cfg: cfg,
+	}
+}
+
+// SendMessages sends the target set of messages to the target peer.
+func (l *LndDaemonAdapters) SendMessages(pub btcec.PublicKey,
+	msgs []lnwire.Message) error {
+
+	return l.cfg.MsgSender.SendMessages(pub, msgs)
+}
+
+// BroadcastTransaction broadcasts a transaction with the target label.
+func (l *LndDaemonAdapters) BroadcastTransaction(tx *wire.MsgTx,
+	label string) error {
+
+	return l.cfg.TxBroadcaster.PublishTransaction(tx, label)
+}
+
+// RegisterConfirmationsNtfn registers an intent to be notified once txid
+// reaches numConfs confirmations.
+func (l *LndDaemonAdapters) RegisterConfirmationsNtfn(txid *chainhash.Hash,
+	pkScript []byte, numConfs, heightHint uint32,
+	opts ...chainntnfs.NotifierOption,
+) (*chainntnfs.ConfirmationEvent, error) {
+
+	return l.cfg.ChainNotifier.RegisterConfirmationsNtfn(
+		txid, pkScript, numConfs, heightHint, opts...,
+	)
+}
+
+// RegisterSpendNtfn registers an intent to be notified once the target
+// outpoint is successfully spent within a transaction.
+func (l *LndDaemonAdapters) RegisterSpendNtfn(outpoint *wire.OutPoint,
+	pkScript []byte, heightHint uint32) (*chainntnfs.SpendEvent, error) {
+
+	return l.cfg.ChainNotifier.RegisterSpendNtfn(
+		outpoint, pkScript, heightHint,
+	)
+}
+
+// A compile time check to ensure that lndDaemonAdapters fully implements the
+// DaemonAdapters interface.
+var _ protofsm.DaemonAdapters = (*LndDaemonAdapters)(nil)