htlcswitch: return error from all encrypt methods

Author: joostjager

htlcswitch/hop/error_encryptor.go

@@ -47,12 +47,12 @@ type ErrorEncrypter interface {
 	// message. This method is used when we receive an
 	// UpdateFailMalformedHTLC from the remote peer and then need to
 	// convert that into a proper error from only the raw bytes.
-	EncryptMalformedError(lnwire.OpaqueReason) lnwire.OpaqueReason
+	EncryptMalformedError(lnwire.OpaqueReason) (lnwire.OpaqueReason, error)
 
 	// IntermediateEncrypt wraps an already encrypted opaque reason error
 	// in an additional layer of onion encryption. This process repeats
 	// until the error arrives at the source of the payment.
-	IntermediateEncrypt(lnwire.OpaqueReason) lnwire.OpaqueReason
+	IntermediateEncrypt(lnwire.OpaqueReason) (lnwire.OpaqueReason, error)
 
 	// Type returns an enum indicating the underlying concrete instance
 	// backing this interface.
@@ -125,9 +125,9 @@ func (s *SphinxErrorEncrypter) EncryptFirstHop(
 //
 // NOTE: Part of the ErrorEncrypter interface.
 func (s *SphinxErrorEncrypter) EncryptMalformedError(
-	reason lnwire.OpaqueReason) lnwire.OpaqueReason {
+	reason lnwire.OpaqueReason) (lnwire.OpaqueReason, error) {
 
-	return s.EncryptError(true, reason)
+	return s.EncryptError(true, reason), nil
 }
 
 // IntermediateEncrypt wraps an already encrypted opaque reason error in an
@@ -138,9 +138,9 @@ func (s *SphinxErrorEncrypter) EncryptMalformedError(
 //
 // NOTE: Part of the ErrorEncrypter interface.
 func (s *SphinxErrorEncrypter) IntermediateEncrypt(
-	reason lnwire.OpaqueReason) lnwire.OpaqueReason {
+	reason lnwire.OpaqueReason) (lnwire.OpaqueReason, error) {
 
-	return s.EncryptError(false, reason)
+	return s.EncryptError(false, reason), nil
 }
 
 // Type returns the identifier for a sphinx error encrypter.

htlcswitch/interceptable_switch.go

@@ -618,7 +618,10 @@ func (f *interceptedForward) Resume() error {
 // Fail notifies the intention to Fail an existing hold forward with an
 // encrypted failure reason.
 func (f *interceptedForward) Fail(reason []byte) error {
-	obfuscatedReason := f.packet.obfuscator.IntermediateEncrypt(reason)
+	obfuscatedReason, err := f.packet.obfuscator.IntermediateEncrypt(reason)
+	if err != nil {
+		return err
+	}
 
 	return f.resolve(&lnwire.UpdateFailHTLC{
 		Reason: obfuscatedReason,

htlcswitch/mock.go

@@ -436,17 +436,21 @@ func (o *mockObfuscator) EncryptFirstHop(failure lnwire.FailureMessage) (
 	return b.Bytes(), nil
 }
 
-func (o *mockObfuscator) IntermediateEncrypt(reason lnwire.OpaqueReason) lnwire.OpaqueReason {
-	return reason
+func (o *mockObfuscator) IntermediateEncrypt(reason lnwire.OpaqueReason) (
+	lnwire.OpaqueReason, error) {
+
+	return reason, nil
 }
 
-func (o *mockObfuscator) EncryptMalformedError(reason lnwire.OpaqueReason) lnwire.OpaqueReason {
+func (o *mockObfuscator) EncryptMalformedError(reason lnwire.OpaqueReason) (
+	lnwire.OpaqueReason, error) {
+
 	var b bytes.Buffer
 	b.Write(fakeHmac)
 
 	b.Write(reason)
 
-	return b.Bytes()
+	return b.Bytes(), nil
 }
 
 // mockDeobfuscator mock implementation of the failure deobfuscator which

htlcswitch/switch.go

@@ -1322,16 +1322,24 @@ func (s *Switch) handlePacketForward(packet *htlcPacket) error {
 					packet.incomingChanID, packet.incomingHTLCID,
 					packet.outgoingChanID, packet.outgoingHTLCID)
 
-				fail.Reason = circuit.ErrorEncrypter.EncryptMalformedError(
-					fail.Reason,
-				)
+				fail.Reason, err = circuit.ErrorEncrypter.
+					EncryptMalformedError(fail.Reason)
+				if err != nil {
+					err = fmt.Errorf("unable to obfuscate "+
+						"malformed error: %v", err)
+					log.Error(err)
+				}
 
 			default:
 				// Otherwise, it's a forwarded error, so we'll perform a
 				// wrapper encryption as normal.
-				fail.Reason = circuit.ErrorEncrypter.IntermediateEncrypt(
-					fail.Reason,
-				)
+				fail.Reason, err = circuit.ErrorEncrypter.
+					IntermediateEncrypt(fail.Reason)
+				if err != nil {
+					err = fmt.Errorf("unable to obfuscate "+
+						"intermediate error: %v", err)
+					log.Error(err)
+				}
 			}
 		} else if !isFail && circuit.Outgoing != nil {
 			// If this is an HTLC settle, and it wasn't from a