This commit introduces a new test case that asserts all of the witness
size constants currently in the codebase. We also reintroduce the
AcceptedHtlcSuccessWitnessSize and OfferedHtlcTimeoutWitnessSize
constants that were recently removed for the sake of completeness.
In asserting the witnes sizes, there were three uncovered discrepancies:
* OfferedHtlcSuccessWitnessSize overestimated by about 30% because it
included an extra signature in the calculation.
* ToLocalPenaltyWitnessSize was underestimated by one byte, because it
was missing the length byte for the OP_TRUE. This has implications
the watchtower protocol since the client and server are assumed to
share the same weight estimates used for signing. This commit keeps
the current behavior, with the intention of rolling out negotiation
for which weight estimate to use for a given session.
* AcceptedHtlcScriptSize was underestimated by one byte because it was
missing a length byte for the value 32 pushed on the stack when
asserting the preimage's length. This affects all AcceptedHtlc*
witness sizes.
We also increase the witness size for these types to account for the 3
extra bytes. The size won't be correct in all cases, but it is just an
upper bound in any case.
Since we never attempt to sweep an HTLC we offered with the preimage on
the remote's commitment, we never use the constant
AcceptedHtlcSuccessWitnessSize for weight estimation. Similarly, we
never timout an HTLC offered by the remote on our own commitment, and
don't need the constant OfferedHtlcTimeoutWitnessSize.
This commit corrects a bug in TxWeightEstimator that could result in
underestimations for transactions involving NestedP2WPKH and NestedP2WSH
inputs. The scriptSig data push is now accounted for in a proper size
constant, and the input count is now incremented in both. This would
only be detectable in the event that the number of non-nested inputs and
the total number of inputs straddle the discontinuities in the
CompactSize encoding, e.g. 253, 2^16-1, or 2^32-1.
This commit is a step to split the lnwallet package. It puts the Input
interface and implementations in a separate package along with all their
dependencies from lnwallet.
