invoices: extract invoice decoding from registry

Previously it was difficult to use the invoice registry in unit tests,
because it used zpay32 to decode the invoice. For that to succeed, a
valid signature is required on the payment request.

This commit injects the decode dependency on a different level so that
it is easier to mock.

invoices/invoiceregistry.go

@@ -7,14 +7,12 @@ import (
 	"sync/atomic"
 	"time"
 
-	"github.com/btcsuite/btcd/chaincfg"
 	"github.com/btcsuite/btcutil"
 	"github.com/davecgh/go-spew/spew"
 	"github.com/lightningnetwork/lnd/channeldb"
 	"github.com/lightningnetwork/lnd/lntypes"
 	"github.com/lightningnetwork/lnd/lnwire"
 	"github.com/lightningnetwork/lnd/queue"
-	"github.com/lightningnetwork/lnd/zpay32"
 )
 
 var (
@@ -52,7 +50,9 @@ type InvoiceRegistry struct {
 	// that *all* nodes are able to fully settle.
 	debugInvoices map[lntypes.Hash]*channeldb.Invoice
 
-	activeNetParams *chaincfg.Params
+	// decodeFinalCltvExpiry is a function used to decode the final expiry
+	// value from the payment request.
+	decodeFinalCltvExpiry func(invoice string) (uint32, error)
 
 	wg   sync.WaitGroup
 	quit chan struct{}
@@ -62,8 +62,8 @@ type InvoiceRegistry struct {
 // wraps the persistent on-disk invoice storage with an additional in-memory
 // layer. The in-memory layer is in place such that debug invoices can be added
 // which are volatile yet available system wide within the daemon.
-func NewRegistry(cdb *channeldb.DB,
+func NewRegistry(cdb *channeldb.DB, decodeFinalCltvExpiry func(invoice string) (
-	activeNetParams *chaincfg.Params) *InvoiceRegistry {
+	uint32, error)) *InvoiceRegistry {
 
 	return &InvoiceRegistry{
 		cdb:                       cdb,
@@ -74,7 +74,7 @@ func NewRegistry(cdb *channeldb.DB,
 		newSingleSubscriptions:    make(chan *SingleInvoiceSubscription),
 		subscriptionCancels:       make(chan uint32),
 		invoiceEvents:             make(chan *invoiceEvent, 100),
-		activeNetParams:           activeNetParams,
+		decodeFinalCltvExpiry:     decodeFinalCltvExpiry,
 		quit:                      make(chan struct{}),
 	}
 }
@@ -430,14 +430,12 @@ func (i *InvoiceRegistry) LookupInvoice(rHash lntypes.Hash) (channeldb.Invoice,
 		return channeldb.Invoice{}, 0, err
 	}
 
-	payReq, err := zpay32.Decode(
+	expiry, err := i.decodeFinalCltvExpiry(string(invoice.PaymentRequest))
-		string(invoice.PaymentRequest), i.activeNetParams,
-	)
 	if err != nil {
 		return channeldb.Invoice{}, 0, err
 	}
 
-	return invoice, uint32(payReq.MinFinalCLTVExpiry()), nil
+	return invoice, expiry, nil
 }
 
 // SettleInvoice attempts to mark an invoice as settled. If the invoice is a

invoices/invoiceregistry_test.go

@@ -10,6 +10,7 @@ import (
 	"github.com/lightningnetwork/lnd/channeldb"
 	"github.com/lightningnetwork/lnd/lntypes"
 	"github.com/lightningnetwork/lnd/lnwire"
+	"github.com/lightningnetwork/lnd/zpay32"
 )
 
 var (
@@ -28,6 +29,14 @@ var (
 	testPayReq = "lnbc500u1pwywxzwpp5nd2u9xzq02t0tuf2654as7vma42lwkcjptx4yzfq0umq4swpa7cqdqqcqzysmlpc9ewnydr8rr8dnltyxphdyf6mcqrsd6dml8zajtyhwe6a45d807kxtmzayuf0hh2d9tn478ecxkecdg7c5g85pntupug5kakm7xcpn63zqk"
 )
 
+func decodeExpiry(payReq string) (uint32, error) {
+	invoice, err := zpay32.Decode(payReq, &chaincfg.MainNetParams)
+	if err != nil {
+		return 0, err
+	}
+	return uint32(invoice.MinFinalCLTVExpiry()), nil
+}
+
 // TestSettleInvoice tests settling of an invoice and related notifications.
 func TestSettleInvoice(t *testing.T) {
 	cdb, cleanup, err := newDB()
@@ -37,7 +46,7 @@ func TestSettleInvoice(t *testing.T) {
 	defer cleanup()
 
 	// Instantiate and start the invoice registry.
-	registry := NewRegistry(cdb, &chaincfg.MainNetParams)
+	registry := NewRegistry(cdb, decodeExpiry)
 
 	err = registry.Start()
 	if err != nil {
@@ -167,7 +176,7 @@ func TestCancelInvoice(t *testing.T) {
 	defer cleanup()
 
 	// Instantiate and start the invoice registry.
-	registry := NewRegistry(cdb, &chaincfg.MainNetParams)
+	registry := NewRegistry(cdb, decodeExpiry)
 
 	err = registry.Start()
 	if err != nil {

server.go

@@ -46,6 +46,7 @@ import (
 	"github.com/lightningnetwork/lnd/sweep"
 	"github.com/lightningnetwork/lnd/ticker"
 	"github.com/lightningnetwork/lnd/tor"
+	"github.com/lightningnetwork/lnd/zpay32"
 )
 
 const (
@@ -284,6 +285,14 @@ func newServer(listenAddrs []net.Addr, chanDB *channeldb.DB, cc *chainControl,
 		readBufferPool, runtime.NumCPU(), pool.DefaultWorkerTimeout,
 	)
 
+	decodeFinalCltvExpiry := func(payReq string) (uint32, error) {
+		invoice, err := zpay32.Decode(payReq, activeNetParams.Params)
+		if err != nil {
+			return 0, err
+		}
+		return uint32(invoice.MinFinalCLTVExpiry()), nil
+	}
+
 	s := &server{
 		chanDB:    chanDB,
 		cc:        cc,
@@ -291,7 +300,7 @@ func newServer(listenAddrs []net.Addr, chanDB *channeldb.DB, cc *chainControl,
 		writePool: writePool,
 		readPool:  readPool,
 
-		invoices: invoices.NewRegistry(chanDB, activeNetParams.Params),
+		invoices: invoices.NewRegistry(chanDB, decodeFinalCltvExpiry),
 
 		channelNotifier: channelnotifier.New(chanDB),