lnwire: update AnnounceSigs2 to use pure TLV

lnwire/announcement_signatures_2_test.go

@@ -0,0 +1,78 @@
+package lnwire
+
+import (
+	"bytes"
+	"testing"
+
+	"github.com/lightningnetwork/lnd/tlv"
+	"github.com/stretchr/testify/require"
+)
+
+// TestAnnSigs2EncodeDecode tests the encoding and decoding of the
+// AnnounceSignatures2 message using hardcoded byte slices.
+func TestAnnSigs2EncodeDecode(t *testing.T) {
+	t.Parallel()
+
+	// We'll create a raw byte stream that represents a valid
+	// AnnounceSignatures2 message with various known and unknown fields in
+	// the signed TLV ranges.
+	var rawBytes []byte
+
+	// ChannelID.
+	rawBytes = append(rawBytes, []byte{
+		0x00, // type
+		0x20, // length
+	}...)
+	rawBytes = append(rawBytes, make([]byte, 32)...) // value
+
+	// ShortChannelID.
+	rawBytes = append(rawBytes, []byte{
+		0x02,                   // type
+		0x08,                   // length
+		0, 0, 1, 0, 0, 2, 0, 3, // value
+	}...)
+
+	// PartialSignature.
+	rawBytes = append(rawBytes, []byte{
+		0x04, // type
+		0x20, // length
+	}...)
+	rawBytes = append(rawBytes, make([]byte, 32)...) // value
+
+	// Extra field in the first signed range.
+	rawBytes = append(rawBytes, []byte{
+		0x30,       // type
+		0x02,       // length
+		0xab, 0xcd, // value
+	}...)
+
+	w := new(bytes.Buffer)
+	var buf [8]byte
+	err := tlv.WriteVarInt(w, pureTLVSignedSecondRangeStart+1, &buf)
+	require.NoError(t, err)
+
+	// Extra field in the second signed range.
+	rawBytes = append(rawBytes, w.Bytes()...) // type
+	rawBytes = append(rawBytes, []byte{
+		0x02,       // length
+		0x79, 0x79, // value
+	}...)
+
+	// Now, create a new empty message and decode the raw bytes into it.
+	msg := &AnnounceSignatures2{}
+	r := bytes.NewReader(rawBytes)
+	err = msg.Decode(r, 0)
+	require.NoError(t, err)
+
+	// At this point, we expect 2 extra signed fields.
+	require.Len(t, msg.ExtraSignedFields, 2)
+
+	// Next, encode the message back into a new byte buffer.
+	var b bytes.Buffer
+	err = msg.Encode(&b, 0)
+	require.NoError(t, err)
+
+	// The re-encoded bytes should be exactly the same as the original raw
+	// bytes.
+	require.Equal(t, rawBytes, b.Bytes())
+}