Based on the current channel type, we derive the script used for the
to_remote output. Currently only the unencumbered p2wkh type is used,
but that will change with upcoming channel types.
createCommitmentTx would earlier mutate the passed commitment struct
after evaluating the htlc view and calculating the final balances, which
was confusing since the balances are supposed to only be *after*
subtracting fees.
Instead we take the needed parameters as arguments, and return the final
balances, tx and fee to populate the commitment struct in a proper way.
Instead of passing delays and dustlimits separately, we pass the correct
channel config to CreateCommitTx from the POV of the local party that
owns the commit tx.
To make it more clear which commitment we are actually creating, we
rename variables to denote local and remote, to prepare for the case
when both outputs might be delayed.
In this commit, we create a new chainfee package, that houses all fee
related functionality used within the codebase. The creation of this new
package furthers our long-term goal of extracting functionality from the
bloated `lnwallet` package into new distinct packages. Additionally,
this new packages resolves a class of import cycle that could arise if a
new package that was imported by something in `lnwallet` wanted to use
the existing fee related functions in the prior `lnwallet` package.
In this commit, we convert the existing `channeldb.ChannelType` type
into a _bit field_. This doesn't require us to change the current
serialization or interpretation or the type as it is, since all the
current defined values us a distinct bit. This PR lays the ground work
for any future changes that may introduce new channel types (like anchor
outputs), and also any changes that may modify the existing invariants
around channels (if we're the initiator, we always have the funding
transaction).
In this commit, we update the channel state machine to be aware of
tweakless commits. In several areas, we'll now check the channel's type
to see if it's `SingleFunderTweakless`. If so, then we'll opt to use the
remote party's non-delay based point directly in the script, skipping
any additional cryptographic operations. Along the way we move the
`validateCommitmentSanity` method to be defined _before_ it's used as is
cutomary within the codebase.
Notably, within the `NewUnilateralCloseSummary` method, we'll now _blank
out_ the `SingleTweak` value if the commitment is tweakless. This
indicates to callers the witness type they should map to, as the value
isn't needed at all any longer when sweeping a non-delay output.
We also update the signing+verification tests to also test that we're
able to properly generate a valid witness for the new tweakless
commitment format.
Now that the success resolver preimage field is always populated by the
incoming contest resolver, preimage lookups earlier in the
process (channel and channel arbitrator) can mostly be removed.
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.
In this commit, we modify the NewUnilateralCloseSummary to be able to
distinguish between a unilateral closure using the lowest+highest
commitment the remote party possesses. Before this commit, if the remote
party broadcast their highest commitment, when they have a lower
unrevoked commitment, then this function would fail to find the proper
output, leaving funds on the chain.
To fix this, it's now the duty of the caller to pass remotePendingCommit
with the proper value. The caller should use the lowest unrevoked
commitment, and the height hint of the broadcast commitment to discern
if this is a pending commitment or not.
lnwire.MilliSatoshi is now a signed integer, as a result, we’ll return
a different error if our balances go to negative due to the inability
to pay a the set fee.
Appendix C of BOLT 03 contains a series of test vectors asserting that
commitment, HTLC success, and HTLC timeout transactions are created
correctly. Here the test cases are transcribed to Go structs and
verified.
We also break out some logic need to tests that bypass the constructor
and remove some redundant fields.
