lnwire: add type CustomRecords

This commit introduces the `CustomRecords` type in the `lnwire` package,
designed to hold arbitrary byte slices. Each entry in this map can
associate with TLV type values that are greater than or equal to 65536.

lnwire/custom_records_test.go

@@ -0,0 +1,198 @@
+package lnwire
+
+import (
+	"bytes"
+	"testing"
+
+	"github.com/lightningnetwork/lnd/fn"
+	"github.com/lightningnetwork/lnd/tlv"
+	"github.com/stretchr/testify/require"
+)
+
+// TestCustomRecords tests the custom records serialization and deserialization,
+// as well as copying and producing records.
+func TestCustomRecords(t *testing.T) {
+	testCases := []struct {
+		name            string
+		customTypes     tlv.TypeMap
+		expectedRecords CustomRecords
+		expectedErr     string
+	}{
+		{
+			name:            "empty custom records",
+			customTypes:     tlv.TypeMap{},
+			expectedRecords: nil,
+		},
+		{
+			name: "custom record with invalid type",
+			customTypes: tlv.TypeMap{
+				123: []byte{1, 2, 3},
+			},
+			expectedErr: "TLV type below min: 65536",
+		},
+		{
+			name: "valid custom record",
+			customTypes: tlv.TypeMap{
+				65536: []byte{1, 2, 3},
+			},
+			expectedRecords: map[uint64][]byte{
+				65536: {1, 2, 3},
+			},
+		},
+		{
+			name: "valid custom records, wrong order",
+			customTypes: tlv.TypeMap{
+				65537: []byte{3, 4, 5},
+				65536: []byte{1, 2, 3},
+			},
+			expectedRecords: map[uint64][]byte{
+				65536: {1, 2, 3},
+				65537: {3, 4, 5},
+			},
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			records, err := NewCustomRecords(tc.customTypes)
+
+			if tc.expectedErr != "" {
+				require.ErrorContains(t, err, tc.expectedErr)
+				return
+			}
+
+			require.NoError(t, err)
+			require.Equal(t, tc.expectedRecords, records)
+
+			// Serialize, then parse the records again.
+			blob, err := records.Serialize()
+			require.NoError(t, err)
+
+			parsedRecords, err := ParseCustomRecords(blob)
+			require.NoError(t, err)
+
+			require.Equal(t, tc.expectedRecords, parsedRecords)
+
+			// Copy() should also return the same records.
+			require.Equal(
+				t, tc.expectedRecords, parsedRecords.Copy(),
+			)
+
+			// RecordProducers() should also allow us to serialize
+			// the records again.
+			serializedProducers := serializeRecordProducers(
+				t, parsedRecords.RecordProducers(),
+			)
+
+			require.Equal(t, blob, serializedProducers)
+		})
+	}
+}
+
+// TestCustomRecordsExtendRecordProducers tests that we can extend a slice of
+// record producers with custom records.
+func TestCustomRecordsExtendRecordProducers(t *testing.T) {
+	testCases := []struct {
+		name           string
+		existingTypes  map[uint64][]byte
+		customRecords  CustomRecords
+		expectedResult tlv.TypeMap
+		expectedErr    string
+	}{
+		{
+			name: "normal merge",
+			existingTypes: map[uint64][]byte{
+				123: {3, 4, 5},
+				345: {1, 2, 3},
+			},
+			customRecords: CustomRecords{
+				65536: {1, 2, 3},
+			},
+			expectedResult: tlv.TypeMap{
+				123:   {3, 4, 5},
+				345:   {1, 2, 3},
+				65536: {1, 2, 3},
+			},
+		},
+		{
+			name: "duplicates",
+			existingTypes: map[uint64][]byte{
+				123:   {3, 4, 5},
+				345:   {1, 2, 3},
+				65536: {1, 2, 3},
+			},
+			customRecords: CustomRecords{
+				65536: {1, 2, 3},
+			},
+			expectedErr: "contains a TLV type that is already " +
+				"present in the existing records: 65536",
+		},
+		{
+			name: "non custom type in custom records",
+			existingTypes: map[uint64][]byte{
+				123:   {3, 4, 5},
+				345:   {1, 2, 3},
+				65536: {1, 2, 3},
+			},
+			customRecords: CustomRecords{
+				123: {1, 2, 3},
+			},
+			expectedErr: "TLV type below min: 65536",
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			nonCustomRecords := tlv.MapToRecords(tc.existingTypes)
+			nonCustomProducers := fn.Map(
+				func(r tlv.Record) tlv.RecordProducer {
+					return &recordProducer{r}
+				}, nonCustomRecords,
+			)
+
+			combined, err := tc.customRecords.ExtendRecordProducers(
+				nonCustomProducers,
+			)
+
+			if tc.expectedErr != "" {
+				require.ErrorContains(t, err, tc.expectedErr)
+				return
+			}
+
+			require.NoError(t, err)
+
+			serializedProducers := serializeRecordProducers(
+				t, combined,
+			)
+
+			stream, err := tlv.NewStream()
+			require.NoError(t, err)
+
+			parsedMap, err := stream.DecodeWithParsedTypes(
+				bytes.NewReader(serializedProducers),
+			)
+			require.NoError(t, err)
+
+			require.Equal(t, tc.expectedResult, parsedMap)
+		})
+	}
+}
+
+// serializeRecordProducers is a helper function that serializes a slice of
+// record producers into a byte slice.
+func serializeRecordProducers(t *testing.T,
+	producers []tlv.RecordProducer) []byte {
+
+	tlvRecords := fn.Map(func(p tlv.RecordProducer) tlv.Record {
+		return p.Record()
+	}, producers)
+
+	stream, err := tlv.NewStream(tlvRecords...)
+	require.NoError(t, err)
+
+	var b bytes.Buffer
+	err = stream.Encode(&b)
+	require.NoError(t, err)
+
+	return b.Bytes()
+}