lnwire+htlcswitch: report height for invalid payment details failure

Extends the invalid payment details failure with the new accept height
field. This allows sender to distinguish between a genuine invalid
details situation and a delay caused by intermediate nodes.

lnwire/onion_error.go

@@ -333,13 +333,19 @@ func (f *FailIncorrectPaymentAmount) Error() string {
 type FailIncorrectDetails struct {
 	// amount is the value of the extended HTLC.
 	amount MilliSatoshi
+
+	// height is the block height when the htlc was received.
+	height uint32
 }
 
 // NewFailIncorrectDetails makes a new instance of the FailIncorrectDetails
-// error bound to the specified HTLC amount.
-func NewFailIncorrectDetails(amt MilliSatoshi) *FailIncorrectDetails {
+// error bound to the specified HTLC amount and acceptance height.
+func NewFailIncorrectDetails(amt MilliSatoshi,
+	height uint32) *FailIncorrectDetails {
+
 	return &FailIncorrectDetails{
 		amount: amt,
+		height: height,
 	}
 }
 
@@ -348,6 +354,11 @@ func (f *FailIncorrectDetails) Amount() MilliSatoshi {
 	return f.amount
 }
 
+// Height is the block height when the htlc was received.
+func (f *FailIncorrectDetails) Height() uint32 {
+	return f.height
+}
+
 // Code returns the failure unique code.
 //
 // NOTE: Part of the FailureMessage interface.
@@ -360,7 +371,8 @@ func (f *FailIncorrectDetails) Code() FailCode {
 // NOTE: Implements the error interface.
 func (f *FailIncorrectDetails) Error() string {
 	return fmt.Sprintf(
-		"%v(amt=%v)", CodeIncorrectOrUnknownPaymentDetails, f.amount,
+		"%v(amt=%v, height=%v)", CodeIncorrectOrUnknownPaymentDetails,
+		f.amount, f.height,
 	)
 }
 
@@ -381,6 +393,17 @@ func (f *FailIncorrectDetails) Decode(r io.Reader, pver uint32) error {
 		return err
 	}
 
+	// At a later stage, the height field was also tacked on. We need to
+	// check for io.EOF here as well.
+	err = ReadElement(r, &f.height)
+	switch {
+	case err == io.EOF:
+		return nil
+
+	case err != nil:
+		return err
+	}
+
 	return nil
 }
 
@@ -388,7 +411,7 @@ func (f *FailIncorrectDetails) Decode(r io.Reader, pver uint32) error {
 //
 // NOTE: Part of the Serializable interface.
 func (f *FailIncorrectDetails) Encode(w io.Writer, pver uint32) error {
-	return WriteElement(w, f.amount)
+	return WriteElements(w, f.amount, f.height)
 }
 
 // FailFinalExpiryTooSoon is returned if the cltv_expiry is too low, the final

lnwire/onion_error_test.go

@@ -37,7 +37,7 @@ var onionFailures = []FailureMessage{
 	&FailIncorrectPaymentAmount{},
 	&FailFinalExpiryTooSoon{},
 
-	NewFailIncorrectDetails(99),
+	NewFailIncorrectDetails(99, 100),
 	NewInvalidOnionVersion(testOnionHash),
 	NewInvalidOnionHmac(testOnionHash),
 	NewInvalidOnionKey(testOnionHash),
@@ -196,6 +196,9 @@ func TestFailIncorrectDetailsOptionalAmount(t *testing.T) {
 	if invalidDetailsErr.amount != 0 {
 		t.Fatalf("expected amount to be zero")
 	}
+	if invalidDetailsErr.height != 0 {
+		t.Fatalf("height incorrect")
+	}
 }
 
 type mockFailIncorrectDetailsNoAmt struct {
@@ -216,3 +219,57 @@ func (f *mockFailIncorrectDetailsNoAmt) Decode(r io.Reader, pver uint32) error {
 func (f *mockFailIncorrectDetailsNoAmt) Encode(w io.Writer, pver uint32) error {
 	return nil
 }
+
+// TestFailIncorrectDetailsOptionalHeight tests that we're able to decode an
+// FailIncorrectDetails error that doesn't have the optional height. This
+// ensures we're able to decode FailIncorrectDetails messages from older nodes.
+func TestFailIncorrectDetailsOptionalHeight(t *testing.T) {
+	t.Parallel()
+
+	onionError := &mockFailIncorrectDetailsNoHeight{
+		amount: uint64(123),
+	}
+
+	var b bytes.Buffer
+	if err := EncodeFailure(&b, onionError, 0); err != nil {
+		t.Fatalf("unable to encode failure: %v", err)
+	}
+
+	onionError2, err := DecodeFailure(bytes.NewReader(b.Bytes()), 0)
+	if err != nil {
+		t.Fatalf("unable to decode error: %v", err)
+	}
+
+	invalidDetailsErr, ok := onionError2.(*FailIncorrectDetails)
+	if !ok {
+		t.Fatalf("expected FailIncorrectDetails, but got %T",
+			onionError2)
+	}
+
+	if invalidDetailsErr.amount != 123 {
+		t.Fatalf("amount incorrect")
+	}
+	if invalidDetailsErr.height != 0 {
+		t.Fatalf("height incorrect")
+	}
+}
+
+type mockFailIncorrectDetailsNoHeight struct {
+	amount uint64
+}
+
+func (f *mockFailIncorrectDetailsNoHeight) Code() FailCode {
+	return CodeIncorrectOrUnknownPaymentDetails
+}
+
+func (f *mockFailIncorrectDetailsNoHeight) Error() string {
+	return ""
+}
+
+func (f *mockFailIncorrectDetailsNoHeight) Decode(r io.Reader, pver uint32) error {
+	return nil
+}
+
+func (f *mockFailIncorrectDetailsNoHeight) Encode(w io.Writer, pver uint32) error {
+	return WriteElement(w, f.amount)
+}