zpay32: add BOLT 11 feature bits and test vectors

zpay32/invoice.go

@@ -67,6 +67,16 @@ const (
 
 	// fieldTypeC contains an optional requested final CLTV delta.
 	fieldTypeC = 24
+
+	// fieldType9 contains one or more bytes for signaling features
+	// supported or required by the receiver.
+	fieldType9 = 5
+)
+
+var (
+	// InvoiceFeatures holds the set of all known feature bits that are
+	// exposed as BOLT 11 features.
+	InvoiceFeatures = map[lnwire.FeatureBit]string{}
 )
 
 // MessageSigner is passed to the Encode method to provide a signature
@@ -146,6 +156,10 @@ type Invoice struct {
 	//
 	// NOTE: This is optional.
 	RouteHints [][]HopHint
+
+	// Features represents an optional field used to signal optional or
+	// required support for features by the receiver.
+	Features *lnwire.FeatureVector
 }
 
 // Amount is a functional option that allows callers of NewInvoice to set the
@@ -663,6 +677,14 @@ func parseTaggedFields(invoice *Invoice, fields []byte, net *chaincfg.Params) er
 			}
 
 			invoice.RouteHints = append(invoice.RouteHints, routeHint)
+		case fieldType9:
+			if invoice.Features != nil {
+				// We skip the field if we have already seen a
+				// supported one.
+				continue
+			}
+
+			invoice.Features, err = parseFeatures(base32Data)
 		default:
 			// Ignore unknown type.
 		}
@@ -874,6 +896,25 @@ func parseRouteHint(data []byte) ([]HopHint, error) {
 	return routeHint, nil
 }
 
+// parseFeatures decodes any feature bits directly from the base32
+// representation.
+func parseFeatures(data []byte) (*lnwire.FeatureVector, error) {
+	rawFeatures := lnwire.NewRawFeatureVector()
+	err := rawFeatures.DecodeBase32(bytes.NewReader(data), len(data))
+	if err != nil {
+		return nil, err
+	}
+
+	fv := lnwire.NewFeatureVector(rawFeatures, InvoiceFeatures)
+	unknownFeatures := fv.UnknownRequiredFeatures()
+	if len(unknownFeatures) > 0 {
+		return nil, fmt.Errorf("invoice contains unknown required "+
+			"features: %v", unknownFeatures)
+	}
+
+	return fv, nil
+}
+
 // writeTaggedFields writes the non-nil tagged fields of the Invoice to the
 // base32 buffer.
 func writeTaggedFields(bufferBase32 *bytes.Buffer, invoice *Invoice) error {
@@ -1024,6 +1065,18 @@ func writeTaggedFields(bufferBase32 *bytes.Buffer, invoice *Invoice) error {
 			return err
 		}
 	}
+	if invoice.Features != nil && invoice.Features.SerializeSize32() > 0 {
+		var b bytes.Buffer
+		err := invoice.Features.RawFeatureVector.EncodeBase32(&b)
+		if err != nil {
+			return err
+		}
+
+		err = writeTaggedField(bufferBase32, fieldType9, b.Bytes())
+		if err != nil {
+			return err
+		}
+	}
 
 	return nil
 }

zpay32/invoice_test.go

@@ -24,12 +24,14 @@ import (
 var (
 	testMillisat24BTC    = lnwire.MilliSatoshi(2400000000000)
 	testMillisat2500uBTC = lnwire.MilliSatoshi(250000000)
+	testMillisat25mBTC   = lnwire.MilliSatoshi(2500000000)
 	testMillisat20mBTC   = lnwire.MilliSatoshi(2000000000)
 
 	testPaymentHashSlice, _ = hex.DecodeString("0001020304050607080900010203040506070809000102030405060708090102")
 
 	testEmptyString    = ""
 	testCupOfCoffee    = "1 cup coffee"
+	testCoffeeBeans    = "coffee beans"
 	testCupOfNonsense  = "ナンセンス 1杯"
 	testPleaseConsider = "Please consider supporting this project"
 
@@ -468,6 +470,59 @@ func TestDecodeEncode(t *testing.T) {
 				i.Destination = nil
 			},
 		},
+		{
+			// On mainnet, please send $30 coffee beans supporting
+			// features 1 and 9.
+			encodedInvoice: "lnbc25m1pvjluezpp5qqqsyqcyq5rqwzqfqqqsyqcyq5rqwzqfqqqsyqcyq5rqwzqfqypqdq5vdhkven9v5sxyetpdees9qzsze992adudgku8p05pstl6zh7av6rx2f297pv89gu5q93a0hf3g7lynl3xq56t23dpvah6u7y9qey9lccrdml3gaqwc6nxsl5ktzm464sq73t7cl",
+			valid:          true,
+			decodedInvoice: func() *Invoice {
+				return &Invoice{
+					Net:         &chaincfg.MainNetParams,
+					MilliSat:    &testMillisat25mBTC,
+					Timestamp:   time.Unix(1496314658, 0),
+					PaymentHash: &testPaymentHash,
+					Description: &testCoffeeBeans,
+					Destination: testPubKey,
+					Features: lnwire.NewFeatureVector(
+						lnwire.NewRawFeatureVector(1, 9),
+						InvoiceFeatures,
+					),
+				}
+			},
+			beforeEncoding: func(i *Invoice) {
+				// Since this destination pubkey was recovered
+				// from the signature, we must set it nil before
+				// encoding to get back the same invoice string.
+				i.Destination = nil
+			},
+		},
+		{
+			// On mainnet, please send $30 coffee beans supporting
+			// features 1, 9, and 100.
+			encodedInvoice: "lnbc25m1pvjluezpp5qqqsyqcyq5rqwzqfqqqsyqcyq5rqwzqfqqqsyqcyq5rqwzqfqypqdq5vdhkven9v5sxyetpdees9q4pqqqqqqqqqqqqqqqqqqszk3ed62snp73037h4py4gry05eltlp0uezm2w9ajnerhmxzhzhsu40g9mgyx5v3ad4aqwkmvyftzk4k9zenz90mhjcy9hcevc7r3lx2sphzfxz7",
+			valid:          false,
+			skipEncoding:   true,
+			decodedInvoice: func() *Invoice {
+				return &Invoice{
+					Net:         &chaincfg.MainNetParams,
+					MilliSat:    &testMillisat25mBTC,
+					Timestamp:   time.Unix(1496314658, 0),
+					PaymentHash: &testPaymentHash,
+					Description: &testCoffeeBeans,
+					Destination: testPubKey,
+					Features: lnwire.NewFeatureVector(
+						lnwire.NewRawFeatureVector(1, 9, 100),
+						InvoiceFeatures,
+					),
+				}
+			},
+			beforeEncoding: func(i *Invoice) {
+				// Since this destination pubkey was recovered
+				// from the signature, we must set it nil before
+				// encoding to get back the same invoice string.
+				i.Destination = nil
+			},
+		},
 		{
 			// On mainnet, with fallback (p2wpkh) address bc1qw508d6qejxtdg4y5r3zarvary0c5xw7kv8f3t4
 			encodedInvoice: "lnbc20m1pvjluezpp5qqqsyqcyq5rqwzqfqqqsyqcyq5rqwzqfqqqsyqcyq5rqwzqfqypqhp58yjmdan79s6qqdhdzgynm4zwqd5d7xmw5fk98klysy043l2ahrqsfppqw508d6qejxtdg4y5r3zarvary0c5xw7kknt6zz5vxa8yh8jrnlkl63dah48yh6eupakk87fjdcnwqfcyt7snnpuz7vp83txauq4c60sys3xyucesxjf46yqnpplj0saq36a554cp9wt865",
@@ -814,6 +869,11 @@ func compareInvoices(expected, actual *Invoice) error {
 		}
 	}
 
+	if !reflect.DeepEqual(expected.Features, actual.Features) {
+		return fmt.Errorf("expected features %v, got %v",
+			expected.Features.RawFeatureVector, actual.Features.RawFeatureVector)
+	}
+
 	return nil
 }