Invoice rpc metadata support

lnrpc/invoicesrpc/addinvoice.go

@@ -157,6 +157,10 @@ type AddInvoiceData struct {
 	// RouteHints are optional route hints that can each be individually
 	// used to assist in reaching the invoice's destination.
 	RouteHints [][]zpay32.HopHint
+
+	// Metadata is additional data that is sent along with the payment to
+	// the payee.
+	Metadata []byte
 }
 
 // BlindedPathConfig holds the configuration values required for blinded path
@@ -489,6 +493,11 @@ func AddInvoice(ctx context.Context, cfg *AddInvoiceConfig,
 	}
 	options = append(options, zpay32.Features(invoiceFeatures))
 
+	// If metadata is provided, add it to the invoice options.
+	if len(invoice.Metadata) > 0 {
+		options = append(options, zpay32.Metadata(invoice.Metadata))
+	}
+
 	// Generate and set a random payment address for this payment. If the
 	// sender understands payment addresses, this can be used to avoid
 	// intermediaries probing the receiver. If the invoice does not have

lnrpc/invoicesrpc/invoices_server.go

@@ -379,6 +379,7 @@ func (s *Server) AddHoldInvoice(ctx context.Context,
 		HodlInvoice:     true,
 		Preimage:        nil,
 		RouteHints:      routeHints,
+		Metadata:        invoice.Metadata,
 	}
 
 	_, dbInvoice, err := AddInvoice(ctx, addInvoiceCfg, addInvoiceData)

lnrpc/invoicesrpc/utils.go

@@ -196,6 +196,7 @@ func CreateRPCInvoice(invoice *invoices.Invoice,
 		PaymentAddr: invoice.Terms.PaymentAddr[:],
 		IsAmp:       invoice.IsAMP(),
 		IsBlinded:   invoice.IsBlinded(),
+		Metadata:    decoded.Metadata,
 	}
 
 	rpcInvoice.AmpInvoiceState = make(map[string]*lnrpc.AMPInvoiceState)

rpcserver.go

@@ -6454,6 +6454,7 @@ func (r *rpcServer) AddInvoice(ctx context.Context,
 		RouteHints:      routeHints,
 		Amp:             invoice.IsAmp,
 		BlindedPathCfg:  blindedPathCfg,
+		Metadata:        invoice.Metadata,
 	}
 
 	if invoice.RPreimage != nil {
@@ -7840,6 +7841,7 @@ func (r *rpcServer) DecodePayReq(ctx context.Context,
 		BlindedPaths:    blindedPaymentPaths,
 		PaymentAddr:     paymentAddr[:],
 		Features:        invoicesrpc.CreateRPCFeatures(payReq.Features),
+		Metadata:        payReq.Metadata,
 	}, nil
 }