lnwire: add invalid onion blinding error code

lnwire/onion_error.go

@@ -81,6 +81,7 @@ const (
 	CodeExpiryTooFar                     FailCode = 21
 	CodeInvalidOnionPayload                       = FlagPerm | 22
 	CodeMPPTimeout                       FailCode = 23
+	CodeInvalidBlinding                           = FlagBadOnion | FlagPerm | 24 //nolint:lll
 )
 
 // String returns the string representation of the failure code.
@@ -158,6 +159,9 @@ func (c FailCode) String() string {
 	case CodeMPPTimeout:
 		return "MPPTimeout"
 
+	case CodeInvalidBlinding:
+		return "InvalidBlinding"
+
 	default:
 		return "<unknown>"
 	}
@@ -1233,6 +1237,51 @@ func (f *FailMPPTimeout) Error() string {
 	return f.Code().String()
 }
 
+// FailInvalidBlinding is returned if there has been a route blinding related
+// error.
+type FailInvalidBlinding struct {
+	OnionSHA256 [sha256.Size]byte
+}
+
+// Code returns the failure unique code.
+//
+// NOTE: Part of the FailureMessage interface.
+func (f *FailInvalidBlinding) Code() FailCode {
+	return CodeInvalidBlinding
+}
+
+// Returns a human readable string describing the target FailureMessage.
+//
+// NOTE: Implements the error interface.
+func (f *FailInvalidBlinding) Error() string {
+	return f.Code().String()
+}
+
+// Decode decodes the failure from bytes stream.
+//
+// NOTE: Part of the Serializable interface.
+func (f *FailInvalidBlinding) Decode(r io.Reader, _ uint32) error {
+	return ReadElement(r, f.OnionSHA256[:])
+}
+
+// Encode writes the failure in bytes stream.
+//
+// NOTE: Part of the Serializable interface.
+func (f *FailInvalidBlinding) Encode(w *bytes.Buffer, _ uint32) error {
+	return WriteBytes(w, f.OnionSHA256[:])
+}
+
+// NewInvalidBlinding creates new instance of FailInvalidBlinding.
+func NewInvalidBlinding(onion []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 {
+		return &FailInvalidBlinding{}
+	}
+
+	return &FailInvalidBlinding{OnionSHA256: sha256.Sum256(onion)}
+}
+
 // DecodeFailure decodes, validates, and parses the lnwire onion failure, for
 // the provided protocol version.
 func DecodeFailure(r io.Reader, pver uint32) (FailureMessage, error) {
@@ -1451,6 +1500,9 @@ func makeEmptyOnionError(code FailCode) (FailureMessage, error) {
 	case CodeMPPTimeout:
 		return &FailMPPTimeout{}, nil
 
+	case CodeInvalidBlinding:
+		return &FailInvalidBlinding{}, nil
+
 	default:
 		return nil, errors.Errorf("unknown error code: %v", code)
 	}

lnwire/onion_error_test.go

@@ -56,6 +56,7 @@ var onionFailures = []FailureMessage{
 	NewFinalIncorrectCltvExpiry(testCtlvExpiry),
 	NewFinalIncorrectHtlcAmount(testAmount),
 	NewInvalidOnionPayload(testType, testOffset),
+	NewInvalidBlinding(testOnionHash),
 }
 
 // TestEncodeDecodeCode tests the ability of onion errors to be properly encoded