Merge pull request #1448 from Roasbeef/check-invoice-min-final

channeldb+htlcswitch: use the final min cltv delta in the invoice when link at exit hop

channeldb/invoice_test.go

@@ -3,6 +3,7 @@ package channeldb
 import (
 	"crypto/rand"
 	"crypto/sha256"
+	prand "math/rand"
 	"reflect"
 	"testing"
 	"time"
@@ -24,6 +25,7 @@ func randInvoice(value lnwire.MilliSatoshi) (*Invoice, error) {
 		Terms: ContractTerm{
 			PaymentPreimage: pre,
 			Value:           value,
+			FinalCltvDelta:  uint16(prand.Int31()),
 		},
 	}
 	i.Memo = []byte("memo")
@@ -66,6 +68,7 @@ func TestInvoiceWorkflow(t *testing.T) {
 	fakeInvoice.PaymentRequest = []byte("")
 	copy(fakeInvoice.Terms.PaymentPreimage[:], rev[:])
 	fakeInvoice.Terms.Value = lnwire.NewMSatFromSatoshis(10000)
+	fakeInvoice.Terms.FinalCltvDelta = uint16(prand.Int31())
 
 	// Add the invoice to the database, this should succeed as there aren't
 	// any existing invoices within the database with the same payment

channeldb/invoices.go

@@ -68,6 +68,13 @@ type ContractTerm struct {
 	// Settled indicates if this particular contract term has been fully
 	// settled by the payer.
 	Settled bool
+
+	// FinalCltvDelta is the lower bound of a delta from the current height
+	// that the HTLC that wishes to settle this invoice MUST carry. This
+	// allows the receiver to specify the time window that should be
+	// available for them to sweep the HTLC on-chain if that becomes
+	// necessary.
+	FinalCltvDelta uint16
 }
 
 // Invoice is a payment invoice generated by a payee in order to request
@@ -79,8 +86,7 @@ type ContractTerm struct {
 // invoices are never deleted from the database, instead a bit is toggled
 // denoting the invoice has been fully settled. Within the database, all
 // invoices must have a unique payment hash which is generated by taking the
-// sha256 of the payment
-// preimage.
+// sha256 of the payment preimage.
 type Invoice struct {
 	// Memo is an optional memo to be stored along side an invoice.  The
 	// memo may contain further details pertaining to the invoice itself,
@@ -361,7 +367,7 @@ func serializeInvoice(w io.Writer, i *Invoice) error {
 		return err
 	}
 
-	return nil
+	return binary.Write(w, byteOrder, i.Terms.FinalCltvDelta)
 }
 
 func fetchInvoice(invoiceNum []byte, invoices *bolt.Bucket) (*Invoice, error) {
@@ -423,6 +429,18 @@ func deserializeInvoice(r io.Reader) (*Invoice, error) {
 		return nil, err
 	}
 
+	// Before we return with the current invoice, we'll check to see if
+	// there's still enough space in the buffer to read out the final ctlv
+	// delta. We'll get an EOF error if there isn't any thing else
+	// lingering in the buffer.
+	err = binary.Read(r, byteOrder, &invoice.Terms.FinalCltvDelta)
+	if err != nil && err != io.EOF {
+		// If we got a non-eof error, then we know there's an actually
+		// issue. Otherwise, it may have been the case that this
+		// summary didn't have the set of optional fields.
+		return nil, err
+	}
+
 	return invoice, nil
 }
 

htlcswitch/link.go

@@ -2258,9 +2258,8 @@ func (l *channelLink) processRemoteAdds(fwdPkg *channeldb.FwdPkg,
 
 			// We'll also ensure that our time-lock value has been
 			// computed correctly.
-			//
-			// TODO(roasbeef): also accept global default?
-			expectedHeight := heightNow + l.cfg.FwrdingPolicy.TimeLockDelta
+			minCltvDelta := uint32(invoice.Terms.FinalCltvDelta)
+			expectedHeight := heightNow + minCltvDelta
 			switch {
 
 			case !l.cfg.DebugHTLC && fwdInfo.OutgoingCTLV < expectedHeight:

rpcserver.go

@@ -2659,7 +2659,8 @@ func (r *rpcServer) AddInvoice(ctx context.Context,
 		Receipt:        invoice.Receipt,
 		PaymentRequest: []byte(payReqString),
 		Terms: channeldb.ContractTerm{
-			Value: amtMSat,
+			Value:          amtMSat,
+			FinalCltvDelta: uint16(payReq.MinFinalCLTVExpiry()),
 		},
 	}
 	copy(i.Terms.PaymentPreimage[:], paymentPreimage[:])