This commit modifies the channel state machine to be able to derive the
proper commitment and second-level HTLC output scripts required by the
new script-enforced leased channel commitment type.
Similar to what we do for witnesses, check that the HTLC weight
constants check out.
They actually do not, since the spec is off by one. We ensure we agree
with the spec.
This to more easily track mismatches if constants and get more accurate
fee estimates for the two channel types.
The non-anchor weight estimates will now be smaller, this is okay since
these constants are only being used for fee estimation (and will now be
more accurate).
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.
