lnwire: add alias to FundingLocked in TLV

This adds an optional short channel id field to the FundingLocked
message that is sent/received as a TLV segment inside the
ExtraOpaqueData field.

lnwire/short_channel_id_test.go

@@ -5,6 +5,7 @@ import (
 	"testing"
 
 	"github.com/davecgh/go-spew/spew"
+	"github.com/stretchr/testify/require"
 )
 
 func TestShortChannelIDEncoding(t *testing.T) {
@@ -39,3 +40,25 @@ func TestShortChannelIDEncoding(t *testing.T) {
 		}
 	}
 }
+
+// TestScidTypeEncodeDecode tests that we're able to properly encode and decode
+// ShortChannelID within TLV streams.
+func TestScidTypeEncodeDecode(t *testing.T) {
+	t.Parallel()
+
+	aliasScid := ShortChannelID{
+		BlockHeight: (1 << 24) - 1,
+		TxIndex:     (1 << 24) - 1,
+		TxPosition:  (1 << 16) - 1,
+	}
+
+	var extraData ExtraOpaqueData
+	require.NoError(t, extraData.PackRecords(&aliasScid))
+
+	var aliasScid2 ShortChannelID
+	tlvs, err := extraData.ExtractRecords(&aliasScid2)
+	require.NoError(t, err)
+
+	require.Contains(t, tlvs, AliasScidRecordType)
+	require.Equal(t, aliasScid, aliasScid2)
+}