This commit refactors the breach arbiter such that it ignores
commitment values below the remote party's dust limit when trying
to sweep funds after a channel breach. The wallet is now
permitted to pass nil sign descriptors for commitment outputs,
which are then ignored by the arbiter.
All non-dust outputs are accumulated into a single slice of
outputs inside the breach arbiter to simplify the internals.
Doing so permitted a work flow that reduces the total number
of allocations made while processing breaches.
The SpendableOutputs is also expanded to include public methods
to access the witness type and sign descriptors, which was useful
in refactoring the craft justice transaction logic.
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.
This commit adds a new responsibility to the breach arbiter: the
service is now responsible for sweeping the commitment outputs to-self,
in the case of a unilateral commitment broadcast by the remote party.
In this new commitment design, this output won’t be immediately
recognized by the wallet due to using a tweaked public key. As a
result, we need to sweep this output into the wallet manually.
A prior commit modified the walletbalance RPC to return satoshi instead
of BTC. As a result, we need to update the SetUp method in the
networkHarness to ensure we expect the proper value when asserting
wallet balances.
In current commit big shift have been made in direction of unit testable
payments scenarios. Previosly two additional structures have been added
which had been spreaded in the lnd package before, and now we apply
them in the lnd itself:
1. ChannelLink - is an interface which represents the subsystem for
managing the incoming htlc requests, applying the changes to the
channel, and also propagating/forwarding it to htlc switch.
2. Switch - is a central messaging bus for all incoming/outgoing htlc's.
The goal of the switch is forward the incoming/outgoing htlc messages
from one channel to another, and also propagate the settle/fail htlc
messages back to original requester.
With this abtractions the folowing schema becomes nearly complete:
abstraction
^
|
| - - - - - - - - - - - - Lightning - - - - - - - - - - - - -
|
| (Switch) (Switch) (Switch)
| Alice <-- channel link --> Bob <-- channel link --> Carol
|
| - - - - - - - - - - - - - TCP - - - - - - - - - - - - - - -
|
| (Peer) (Peer) (Peer)
| Alice <----- tcp conn --> Bob <---- tcp conn -----> Carol
This commit adds the FeeEstimator interface, which can be used for
future fee calculation implementations. Currently, there is only the
StaticFeeEstimator implementation, which returns the same fee rate for
any transaction.
This commit fixes a slight logic error in the breachArbiter. Previously
we wouldn’t watch a pending channel for closure if the regular
(settled) balance was non-zero. However, this was incorrect, as it’s
possible for us to be on the receiving side of a channel force closure.
This error would leave certain channels as “pending close zombies”
forever until a user manually deleted the entry (or promoted it to be
fully closed).
To fix this, we now utilize the new `TimeLockedBalance` field to make a
better judgment as to if the utxoNursery is watching over a channel or
not.
This commit adds a start up check to the breachArbiter: it will now
watch all channels which are in the “pending closed” state, to ensure
that state of the database is up to date at all times. Once any of the
closing transactions for these channels have been confirmed, then they
will properly be marked as such within the database.
This commit modifies the breachArbiter to properly mark a channel as
_fully_ closed once the transaction which force closed the channel has
been confirmed within the chain.
This commit modifies the logic of the contract hand-off within the
breachArbiter to ensure that only a single internal closeObserver
goroutine is ever active for a given contract.
This modification cleans up the logs in the case of multiple
reconnections and may possible eliminate some non-deterministic bugs
related to channel force closures.
This commit moves the fetching of active channels from the
contractObserver goroutine up to the Start() method on the
breachArbiter. By doing this, we ensure that the user receives an error
(under the current set up) if the btcd node that lnd is connected to
doesn’t have their txindex enabled.
This commit makes a large number of minor changes concerning API usage
within the deamon to match the latest version on the upstream btcsuite
libraries.
The major changes are the switch from wire.ShaHash to chainhash.Hash,
and that wire.NewMsgTx() now takes a paramter indicating the version of
the transaction to be created.
This commit fixes s bug in the breachArbiter which was introduced
during the change that added the live channel hand off from an active
peer. Rather than closing the settle channel of the _older_
breachObserver, the settle channel of the newer beachObserver was being
closed. This would result in a panic once the channel itself was
actually settled as the channel would be closed again.
To fix this bug, we now properly close the channel of the old settle
signal instead of the new one.
This commit modifies the interaction between the breachArbiter and the
peer struct such that the breachArbiter _always_ has the latest version
of a contract.
Prior to this commit once we connected out to a peer which we had an
active contract with and the breachArbiter was watching, we’d have two
copies of the channel in memory, instead of just a single one. This was
wasteful and caused some duplicated log messages due to two instances
of the channel being active.
This commit introduces a new sub-system into the daemon whose job it is
to vigilantly watch for any potential channel breaches throughout the
up-time of the daemon. The logic which was moved from the utxoNursery
in a prior commit now resides within the breachArbiter.
Upon start-up the breachArbiter will query the database for all active
channels, launching a goroutine for each channel in order to be able to
take action if a channel breach is detected. The breachArbiter is also
responsible for notifying the htlcSwitch about channel breaches in
order to black-list the breached linked during any multi-hop forwarding
decisions.
