This commit removes the breach transaction from the
arguments passed to NewBreachRetribution. We already
keep all prior remote commitments on disk in the
commitment log, and load that transaction from disk
inside the method. In practice, the one loaded from
disk will be the same one that is passed in by the
caller, so there should be no change in behavior
as we've already derived the appropriate state number.
This changes makes integration with the watchtower
client simpler, since we no longer need to acquire
the breaching commitment transaction to be able to
construct the BreachRetribution. This simplifies
not only the logic surrounding transient backsups,
but also on startup (and later, retroactively
backing up historic updates).
In this commit, we remove the per channel `sigPool` within the
`lnwallet.LightningChannel` struct. With this change, we ensure that as
the number of channels grows, the number of gouroutines idling in the
sigPool stays constant. It's the case that currently on the daemon, most
channels are likely inactive, with only a hand full actually
consistently carrying out channel updates. As a result, this change
should reduce the amount of idle CPU usage, as we have less active
goroutines in select loops.
In order to make this change, the `SigPool` itself has been publicly
exported such that outside callers can make a `SigPool` and pass it into
newly created channels. Since the sig pool now lives outside the
channel, we were also able to do away with the Stop() method on the
channel all together.
Finally, the server is the sub-system that is currently responsible for
managing the `SigPool` within lnd.
This commit is a follow up to the prior commit which fixed a rounding
error bug in lnwallet. For uniformity, we also fix other occurrences in
the breach arbiter, as well as the integration tests.
In this commit, we address an un accounted for case during the breach
remedy process. If the remote node actually went directly to the second
layer during a channel breach attempt, then we wouldn’t properly be
able to sweep with out justice transaction, as some HTLC inputs may
actually be spent at that point.
In order to address this case, we’ll now catch the transaction
rejection, then check to see which input was spent, promote that to a
second level spend, and repeat as necessary. At the end of this loop,
any inputs which have been spent to the second level will have had the
prevouts and witnesses updated.
In order to perform this transition, we now also store the second level
witness script in the database. This allow us to modify the sign desc
with the proper input value, as well as witness script.
This commit introduces a RetributionStore interface, which
establishes the methods used to access persisted information
regarding breached channels. A RetributionStore is used to
persist retributionInfo regarding all channels for which
the wallet has signaled a breach.
The current design could be improved by moving certain
functionality, e.g. closing channels and htlc links, such
that they are handled by upstream by their respective
subsystems. This was investigated, but deemed preferable to
postpone to a later update to prevent the current
implementation from sprawling amongst too many packages.
The test suite creates a mockRetributionStore and ensures that
it exhibits the same behavior as the retribution store backed
by a channeldb.DB.
This commit adds a breached contract retribution storage layer using
boltdb to the breach arbiter. The breach arbiter now stores retribution
state on disk between detecting a contract breach, broadcasting a
justice transaction that sweeps the channel, and finally witnessing the
justice transaction confirm on the blockchain. It is critical that such
state is persisted on disk, so that if our node restarts at any point
during the retribution procedure, we can recover and continue from the
persisted state.
