channeldb: add KeyLocator Record

channeldb/channel.go

@@ -3657,3 +3657,38 @@ func storeThawHeight(chanBucket kvdb.RwBucket, height uint32) error {
 func deleteThawHeight(chanBucket kvdb.RwBucket) error {
 	return chanBucket.Delete(frozenChanKey)
 }
+
+// EKeyLocator is an encoder for keychain.KeyLocator.
+func EKeyLocator(w io.Writer, val interface{}, buf *[8]byte) error {
+	if v, ok := val.(*keychain.KeyLocator); ok {
+		err := tlv.EUint32T(w, uint32(v.Family), buf)
+		if err != nil {
+			return err
+		}
+
+		return tlv.EUint32T(w, v.Index, buf)
+	}
+	return tlv.NewTypeForEncodingErr(val, "keychain.KeyLocator")
+}
+
+// DKeyLocator is a decoder for keychain.KeyLocator.
+func DKeyLocator(r io.Reader, val interface{}, buf *[8]byte, l uint64) error {
+	if v, ok := val.(*keychain.KeyLocator); ok {
+		var family uint32
+		err := tlv.DUint32(r, &family, buf, 4)
+		if err != nil {
+			return err
+		}
+		v.Family = keychain.KeyFamily(family)
+
+		return tlv.DUint32(r, &v.Index, buf, 4)
+	}
+	return tlv.NewTypeForDecodingErr(val, "keychain.KeyLocator", l, 8)
+}
+
+// MakeKeyLocRecord creates a Record out of a KeyLocator using the passed
+// Type and the EKeyLocator and DKeyLocator functions. The size will always be
+// 8 as KeyFamily is uint32 and the Index is uint32.
+func MakeKeyLocRecord(typ tlv.Type, keyLoc *keychain.KeyLocator) tlv.Record {
+	return tlv.MakeStaticRecord(typ, keyLoc, 8, EKeyLocator, DKeyLocator)
+}

channeldb/channel_test.go

@@ -8,6 +8,8 @@ import (
 	"runtime"
 	"testing"
 
+	"github.com/stretchr/testify/require"
+
 	"github.com/btcsuite/btcd/btcec"
 	"github.com/btcsuite/btcd/chaincfg/chainhash"
 	"github.com/btcsuite/btcd/wire"
@@ -50,6 +52,9 @@ var (
 		IP:   net.ParseIP("127.0.0.1"),
 		Port: 18555,
 	}
+
+	// keyLocIndex is the KeyLocator Index we use for TestKeyLocatorEncoding.
+	keyLocIndex = uint32(2049)
 )
 
 // testChannelParams is a struct which details the specifics of how a channel
@@ -1587,3 +1592,33 @@ func TestHasChanStatus(t *testing.T) {
 		})
 	}
 }
+
+// TestKeyLocatorEncoding tests that we are able to serialize a given
+// keychain.KeyLocator. After successfully encoding, we check that the decode
+// output arrives at the same initial KeyLocator.
+func TestKeyLocatorEncoding(t *testing.T) {
+	keyLoc := keychain.KeyLocator{
+		Family: keychain.KeyFamilyRevocationRoot,
+		Index:  keyLocIndex,
+	}
+
+	// First, we'll encode the KeyLocator into a buffer.
+	var (
+		b   bytes.Buffer
+		buf [8]byte
+	)
+
+	err := EKeyLocator(&b, &keyLoc, &buf)
+	require.NoError(t, err, "unable to encode key locator")
+
+	// Next, we'll attempt to decode the bytes into a new KeyLocator.
+	r := bytes.NewReader(b.Bytes())
+	var decodedKeyLoc keychain.KeyLocator
+
+	err = DKeyLocator(r, &decodedKeyLoc, &buf, 8)
+	require.NoError(t, err, "unable to decode key locator")
+
+	// Finally, we'll compare that the original KeyLocator and the decoded
+	// version are equal.
+	require.Equal(t, keyLoc, decodedKeyLoc)
+}