This commit morphs the prior CancelHTLC into the new UpdateFailHTLC
message and also gets rid of the obsolete HLTCAddReject message while
we’re at it.
The primary change from the CancelHTLC message to the UpdateFailHTLC
message is that the CancelReason is now simply called Reason and that
it’s now an opaque encrypted set of bytes. With this update the failure
messages are now more flexible (they can even carry new
ChannelUpdate’s) and also don’t reveal the exact cause of failure to
intermediate nodes.
This commit adds a new HTLC error type: IncorrectValue. This error type
is to be used when an HTLC that’s extended to the final destination
does not match the expectation of the destination.
This commit adds a new field to the CancelHTLC message which describes
the event that led to an HTLC being cancelled up stream.
A new enum has been added which describers the “why” concerning the
cancellation of the HTLC. Currently the encoding and back propagation
of the errors aren’t properly implemented as defined within the spec.
As a result the current error types provide to privacy as the error are
in plain-site rather doing being properly encrypted.
This commit removes the previous HTLC timeout in message in favor of a
HTLC cancel message. Within the protocol, a timeout message would never
be sent backwards along the route as in the case of an HTLC timeout
before/after the grace period, the course of action taken would be to
broadcast the current commitment transaction unilaterally on-chain.
