lnwire+htlcswitch: change NewInvalidBlinding to use array instead of slice

htlcswitch/link.go

@@ -3468,11 +3468,6 @@ func (l *channelLink) processRemoteAdds(fwdPkg *channeldb.FwdPkg,
 		// or are able to settle it (and it adheres to our fee related
 		// constraints).
 
-		// Fetch the onion blob that was included within this processed
-		// payment descriptor.
-		var onionBlob [lnwire.OnionPacketSize]byte
-		copy(onionBlob[:], pd.OnionBlob[:])
-
 		// Before adding the new htlc to the state machine, parse the
 		// onion object in order to obtain the routing information with
 		// DecodeHopIterator function which process the Sphinx packet.
@@ -3581,7 +3576,7 @@ func (l *channelLink) processRemoteAdds(fwdPkg *channeldb.FwdPkg,
 			l.cfg.DisallowRouteBlinding {
 
 			failure := lnwire.NewInvalidBlinding(
-				onionBlob[:],
+				fn.Some(pd.OnionBlob),
 			)
 			l.sendHTLCError(
 				pd, NewLinkError(failure), obfuscator, false,
@@ -4027,7 +4022,9 @@ func (l *channelLink) sendIncomingHTLCFailureMsg(htlcIndex uint64,
 
 		// The specification does not require that we set the onion
 		// blob.
-		failureMsg := lnwire.NewInvalidBlinding(nil)
+		failureMsg := lnwire.NewInvalidBlinding(
+			fn.None[[lnwire.OnionPacketSize]byte](),
+		)
 		reason, err := e.EncryptFirstHop(failureMsg)
 		if err != nil {
 			return err

lnwire/onion_error.go

@@ -10,6 +10,7 @@ import (
 
 	"github.com/davecgh/go-spew/spew"
 	"github.com/go-errors/errors"
+	"github.com/lightningnetwork/lnd/fn"
 	"github.com/lightningnetwork/lnd/tlv"
 )
 
@@ -1271,14 +1272,19 @@ func (f *FailInvalidBlinding) Encode(w *bytes.Buffer, _ uint32) error {
 }
 
 // NewInvalidBlinding creates new instance of FailInvalidBlinding.
-func NewInvalidBlinding(onion []byte) *FailInvalidBlinding {
+func NewInvalidBlinding(
+	onion fn.Option[[OnionPacketSize]byte]) *FailInvalidBlinding {
 	// The spec allows empty onion hashes for invalid blinding, so we only
 	// include our onion hash if it's provided.
-	if onion == nil {
+	if onion.IsNone() {
 		return &FailInvalidBlinding{}
 	}
 
-	return &FailInvalidBlinding{OnionSHA256: sha256.Sum256(onion)}
+	shaSum := fn.MapOptionZ(onion, func(o [OnionPacketSize]byte) [32]byte {
+		return sha256.Sum256(o[:])
+	})
+
+	return &FailInvalidBlinding{OnionSHA256: shaSum}
 }
 
 // DecodeFailure decodes, validates, and parses the lnwire onion failure, for

lnwire/onion_error_test.go

@@ -9,11 +9,12 @@ import (
 	"testing"
 
 	"github.com/davecgh/go-spew/spew"
+	"github.com/lightningnetwork/lnd/fn"
 	"github.com/stretchr/testify/require"
 )
 
 var (
-	testOnionHash     = []byte{}
+	testOnionHash     = [OnionPacketSize]byte{}
 	testAmount        = MilliSatoshi(1)
 	testCtlvExpiry    = uint32(2)
 	testFlags         = uint16(2)
@@ -43,9 +44,9 @@ var onionFailures = []FailureMessage{
 	&FailMPPTimeout{},
 
 	NewFailIncorrectDetails(99, 100),
-	NewInvalidOnionVersion(testOnionHash),
-	NewInvalidOnionHmac(testOnionHash),
-	NewInvalidOnionKey(testOnionHash),
+	NewInvalidOnionVersion(testOnionHash[:]),
+	NewInvalidOnionHmac(testOnionHash[:]),
+	NewInvalidOnionKey(testOnionHash[:]),
 	NewTemporaryChannelFailure(&testChannelUpdate),
 	NewTemporaryChannelFailure(nil),
 	NewAmountBelowMinimum(testAmount, testChannelUpdate),
@@ -56,7 +57,7 @@ var onionFailures = []FailureMessage{
 	NewFinalIncorrectCltvExpiry(testCtlvExpiry),
 	NewFinalIncorrectHtlcAmount(testAmount),
 	NewInvalidOnionPayload(testType, testOffset),
-	NewInvalidBlinding(testOnionHash),
+	NewInvalidBlinding(fn.Some(testOnionHash)),
 }
 
 // TestEncodeDecodeCode tests the ability of onion errors to be properly encoded