challenger: add LNCChallenger

Author: positiveblue

challenger/lnc.go

@@ -0,0 +1,84 @@
+package challenger
+
+import (
+	"fmt"
+	"time"
+
+	"github.com/lightninglabs/aperture/lnc"
+	"github.com/lightningnetwork/lnd/lnrpc"
+	"github.com/lightningnetwork/lnd/lntypes"
+)
+
+// LNCChallenger is a challenger that uses LNC to connect to an lnd backend to
+// create new LSAT payment challenges.
+type LNCChallenger struct {
+	lndChallenger *LndChallenger
+	nodeConn      *lnc.NodeConn
+}
+
+// NewLNCChallenger creates a new challenger that uses the given LNC session to
+// connect to an lnd backend to create payment challenges.
+func NewLNCChallenger(session *lnc.Session, lncStore lnc.Store,
+	genInvoiceReq InvoiceRequestGenerator,
+	errChan chan<- error) (*LNCChallenger, error) {
+
+	nodeConn, err := lnc.NewNodeConn(session, lncStore)
+	if err != nil {
+		return nil, fmt.Errorf("unable to connect to lnd using lnc: %w",
+			err)
+	}
+
+	client, err := nodeConn.Client()
+	if err != nil {
+		return nil, err
+	}
+
+	lndChallenger, err := NewLndChallenger(
+		client, genInvoiceReq, nodeConn.CtxFunc, errChan,
+	)
+	if err != nil {
+		return nil, err
+	}
+
+	err = lndChallenger.Start()
+	if err != nil {
+		return nil, err
+	}
+
+	return &LNCChallenger{
+		lndChallenger: lndChallenger,
+		nodeConn:      nodeConn,
+	}, nil
+}
+
+// Stop stops the challenger.
+func (l *LNCChallenger) Stop() {
+	err := l.nodeConn.Stop()
+	if err != nil {
+		log.Errorf("unable to stop lnc node conn: %v", err)
+	}
+
+	l.lndChallenger.Stop()
+}
+
+// NewChallenge creates a new LSAT payment challenge, returning a payment
+// request (invoice) and the corresponding payment hash.
+//
+// NOTE: This is part of the mint.Challenger interface.
+func (l *LNCChallenger) NewChallenge(price int64) (string, lntypes.Hash,
+	error) {
+
+	return l.lndChallenger.NewChallenge(price)
+}
+
+// VerifyInvoiceStatus checks that an invoice identified by a payment
+// hash has the desired status. To make sure we don't fail while the
+// invoice update is still on its way, we try several times until either
+// the desired status is set or the given timeout is reached.
+//
+// NOTE: This is part of the auth.InvoiceChecker interface.
+func (l *LNCChallenger) VerifyInvoiceStatus(hash lntypes.Hash,
+	state lnrpc.Invoice_InvoiceState, timeout time.Duration) error {
+
+	return l.lndChallenger.VerifyInvoiceStatus(hash, state, timeout)
+}