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.
Exclusive group is a static property that doesn't need to be updated.
Requiring the exclusive group to be passed into UpdateParams creates a
burden for the caller to make sure they supply the existing group.
This change will be beneficial for users that bump anchor sweeps that
have exclusive groups set.
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.
Allows certain sweep inputs to be kept in separate transactions at all
times. This is a preparation for anchor outputs. Before the commitment
tx confirms, there are three potential anchors that can be cpfp'ed. We
want to cpfp them all, but if done in the same transaction, the
transaction would guaranteed to be invalid. Exponential backoff would
eventually get the txes published, but having exclusive groups makes the
process faster.
Previously only the fee rate used for the last sweep (the sweep bucket
average) was reported. This commit adds the request fee preference to
the report, which is used to select a bucket and the sweep tx fee rate.
This commit allows sweeper to sweep inputs that on its own are not able
to form a sweep transaction that meets the dust limit.
This functionality is useful for sweeping small outputs. In the future,
this will be particularly important to sweep anchors. Anchors will
typically be spent with a relatively large fee to pay for the parent tx.
It will then be necessary to attach an additional wallet utxo.
A refactoring that introduces no functional changes. This prepares for
the addition of wallet utxos to push the sweep tx above the dust limit.
It also enabled access to input-specific sweep parameters during tx
generation. This will be used in later commits to control the sweep
process.
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.
Because the BestBlock method of ChainIO is not exposed through any
RPC we want to get rid of it so we can use the sweeper outside of
lnd too. Since the chain notifier now also delivers the current best
block we don't need the BestBlock method any more.
In this commit, we update the `CommitSpendNoDelay` method to be aware of
the alternate spending mechanism for commitments that don't have a tweak
for the remote party's non-delay output. We also add a new witness type
so callers can convey their expected signing path.
In this commit, we introduce the ability to bump the fee of an input
within the UtxoSweeper. Once its fee rate is bumped, a replacement
transaction (RBF) will be broadcast with the newer fee rate (assuming
the newer fee rate is high enough to be valid), replacing any
conflicting lower fee rate transactions.
Note that this currently doesn't validate the fee preference of the
bump. This responsibility is delegated to the caller, so care must be
taken to ensure the new fee preference is sufficient.
In this commit, we address another issue that arose with the
introduction of the fee rate buckets. We'll use an example to explain
the problem space:
Let's say we have inputs A, B, and C within the same fee rate bucket. If
A's fee rate is bumped to a higher bucket, then it's currently possible
for the lower fee rate bucket to be swept first, which would produce an
invalid RBF transaction since we're removing an input from the original
without providing a higher fee. By the time we get to the higher fee
rate bucket, we broadcast a valid RBF transaction _only_ sweeping input
A, which would evict the transaction sweeping inputs B and C from the
mempool.
To prevent this eviction, we can simply broadcast the higher fee rate
sweep transactions first, to ensure we have valid RBF transactions.
In this commit, we introduce support for arbitrary client fee
preferences when accepting input sweep requests. This is possible with
the addition of fee rate buckets. Fee rate buckets are buckets that
contain inputs with similar fee rates within a specific range, e.g.,
1-10 sat/vbyte, 11-20 sat/vbyte, etc. Having these buckets allows us to
batch and sweep inputs from different clients with similar fee rates
within a single transaction, allowing us to save on chain fees.
With this addition, we can now get rid of the UtxoSweeper's default fee
preference. As of this commit, any clients using the it to sweep inputs
specify the same fee preference to not change their behavior. Each of
these can be fine-tuned later on given their use cases.
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 add a new function, CraftSweepAllTx. This function
allows callers to craft a transaction which sweeps ALL outputs from the
wallet to a single target address. It can either be used for UTXO
consolidation (at the cost of privacy by co-mingling inputs), or simply
to sweep all funds out of a wallet for various reasons.
In an attempt to ensure this method is loosely coupled and testable, for
all behavior structs, we create brand new interface to accept. This
ensures that we only rely on the minimal number of methods needed to
perform our duty.
In this commit, we update the `getInputWitnessSizeUpperBound` and all
its callers to be aware of nested p2sh witness inputs. We do so by
adding another bool which is true if the output is a nested p2sh output.
If so, then in order to properly estimate the total weight, the caller
needs to factor in the non-witness data of the additional sigScript data
push.
In this commit, we extend the WitnessGenerator type to now return an
InputScript. This allows it to be more encompassing, as now callers can
expect a sigScript to be populated if the input being swept requires a
sigScript field.
Along the way, we've also renamed input.BuildWitness to
input.CraftInputScript. We also take a step towards allowing the
sweeper to sweep transactions for n2pwkh outputs. We do so by modifying
the BuiltWitness method to instead return an InputScript. Additionally,
when populating inputs if a sigScript is present, it will now be
populated.
In this commit, we extract the existing determineFeePerKw method on the
RPC server into a new file in the sweep package. Along the way, we
consolidate code by introducing a new FeePreference struct, which allows
the caller to express their fee preference either in blocks to
confirmation, or a direct fee rate. This move takes a small step to
father decoupling calls in the main RPC server.
