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htlcswitch: properly convert multi-hop malformed HTLC failures

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In this commit, we now properly convert multi-hop malformed HTLC
failures. Before this commit, we wouldn't properly add a layer of
encryption to these errors meaning that the destination would fail to
decrypt the error as it was actually plaintext.

To remedy this, we'll now check if we need to convert an error, and if
so we'll encrypt it as if it we were the source of the error (the true
source is our direct channel peer).
This commit is contained in:
Olaoluwa Osuntokun 2019-04-30 18:27:11 -07:00
parent cdc4aca40f
commit be63c7d286
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GPG Key ID: CE58F7F8E20FD9A2
1 changed files with 22 additions and 4 deletions
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26
htlcswitch/switch.go
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@ -1155,13 +1155,12 @@ func (s *Switch) handlePacketForward(packet *htlcPacket) error {
fail, isFail := htlc.(*lnwire.UpdateFailHTLC)
if isFail && !packet.hasSource {
switch {
// No message to encrypt, locally sourced payment.
case circuit.ErrorEncrypter == nil:
// No message to encrypt, locally sourced
// payment.
// If this is a resolution message, then we'll need to
// encrypt it as it's actually internally sourced.
case packet.isResolution:
// If this is a resolution message, then we'll need to encrypt
// it as it's actually internally sourced.
var err error
// TODO(roasbeef): don't need to pass actually?
failure := &lnwire.FailPermanentChannelFailure{}
@ -1174,6 +1173,25 @@ func (s *Switch) handlePacketForward(packet *htlcPacket) error {
log.Error(err)
}
// Alternatively, if the remote party send us an
// UpdateFailMalformedHTLC, then we'll need to convert
// this into a proper well formatted onion error as
// there's no HMAC currently.
case packet.convertedError:
log.Infof("Converting malformed HTLC error "+
"for circuit for Circuit(%x: "+
"(%s, %d) <-> (%s, %d))", packet.circuit.PaymentHash,
packet.incomingChanID, packet.incomingHTLCID,
packet.outgoingChanID, packet.outgoingHTLCID)
fail.Reason = circuit.ErrorEncrypter.EncryptMalformedError(
fail.Reason,
)
if err != nil {
err = fmt.Errorf("unable to obfuscate "+
"error: %v", err)
log.Error(err)
}
default:
// Otherwise, it's a forwarded error, so we'll perform a
// wrapper encryption as normal.