Earlier the channel arbitrator would fail to recognize channels pending
close that were in the breached state. This lead to the state machine
not progressing correctly, and in some cases crashing since we would
attempt to force close an already closed channel.
A test TestChannelArbitratorForceCloseBreachedChannel is added to
exercise one of these scenarios.
Earlier we would not react to breaches, as these are handled by other
subsystems. Now we advances our state machine in case of breach, such
that we'll gracefully exit, and won't have leftover state in case of a
restart.
A simple test TestChannelArbitratorBreachClose to exercise this behavior
is added.
This commit modifies hodl htlc notification from invoice registry from a
single notification per hash to distinct notifications per htlc. This
prepares for htlc-specific information (accept height) to be added to the
notification.
This commit fixes the 'unable to find incoming resolution' error that
occured when trying to resolve incoming htlcs below the dust limit that
are not actually present on the commitment tx.
Previously the invoice registry wasn't aware of replayed htlcs. This was
dealt with by keeping the invoice accept/settle logic idempotent, so
that a replay wouldn't have an effect.
This mechanism has two limitations:
1. No accurate tracking of the total amount paid to an invoice. The total
amount couldn't just be increased with every htlc received, because it
could be a replay which would lead to counting the htlc amount multiple
times. Therefore the total amount was set to the amount of the first
htlc that was received, even though there may have been multiple htlcs
paying to the invoice.
2. Impossible to check htlc expiry consistently for hodl invoices. When
an htlc is new, its expiry needs to be checked against the invoice cltv
delta. But for a replay, that check must be skipped. The htlc was
accepted in time, the invoice was moved to the accepted state and a
replay some blocks later shouldn't lead to that htlc being cancelled.
Because the invoice registry couldn't recognize replays, it stopped
checking htlc expiry heights when the invoice reached the accepted
state. This prevents hold htlcs from being cancelled after a restart.
But unfortunately this also caused additional htlcs to be accepted on an
already accepted invoice without their expiry being checked.
In this commit, the invoice registry starts to persistently track htlcs
so that replays can be recognized. For replays, an htlc resolution
action is returned early. This fixes both limitations mentioned above.
Currently the invoice registry cannot tell apart the htlcs that pay to
an invoice. Because htlcs may also be replayed on startup, it isn't
possible to determine the total amount paid to an invoice.
This commit is a first step towards fixing that. It reports the circuit
keys of htlcs to the invoice registry, which forms the basis for
accurate invoice accounting.
In this commit, we update the `HopIterator` to gain awareness of the new
TLV hop payload. The default `HopIterator` will now hide the details of
the TLV from the caller, and return the same `ForwardingInfo` struct in
a uniform manner. We also add a new method: `ExtraOnionBlob` to allow
the caller to obtain the raw EOB (the serialized TLV stream) to pass
around.
Within the link, we'll now pass the EOB information into the invoice
registry. This allows the registry to parse out any additional
information from the EOB that it needs to settle the payment, such as a
preimage shard in the AMP case.
In this commit, we make a series of changes to ensure that we'll be able
to properly survive restarts if we crash right after we call
MarkChannelClosed. In order to ensure we can survive restarts, we'll now
long the confirmed CommitSet to disk right before we close the channel.
Upon restart, we'll read these from disk so we can pick up where we left
over.
Additionally, we also will now consult the legacy chain actions if it
turns out that the channel has been closed, but we don't have a
confCommitSet written to disk. This will only be the case for nodes that
had pending close channels before this commitment.
In this commit, we add storage to the Briefcase for reading/writing a
confirmed CommitSet. This will be used in follow up commits to ensure
that we're able to survive restarts after we mark a channel as pending
closed. Along the way, we also re-add the FetchChainActions struct as
legacy nodes will need this storage.
Since we no longer have up to date chain actions on disk, we'll use the
HTLC sets in memory which contain the necessary information we need to
in order to obtain the HTLC amounts.
In this commit, we change the behavior of the channel arb to no longer
write chain actions to disk. Instead, using the new CommitSet struct,
we'll replay our set of prior actions based on what actually got into
the chain. As a result, we no longer need to write the chain actions at
all, instead they're reconstructed at run time to determine decisions,
and before any commitments are broadcast in order to determine if we
need to go to chain at all.
In this commit, we add a new `checkLocalChainActions` method. This
method differs from the existing `checkChainActions` method in that it's
only concerned with actions we should take on chain for our local state
based on the local _and_ remote state. This change ensures that we'll
now to go to chain order to cancel an HTLC that was on the remote
party's commitment transaction, but not our own.
In this commit, we fix a lingering TOOD statement in the channel arb.
Before this commitment, we would simply wipe our our local HTLC set of
the HTLC set that was on the remote commitment transaction on force
close. This was incorrect as if our commitment transaction had an HTLC
that the remote commitment didn't, then we would fail to cancel that
back, and cause both channels to time out on chain.
In order to remedy this, we introduce a new `HtlcSetKey` struct to track
all 3 possible in-flight set of HTLCs: ours, theirs, and their pending.
We also we start to tack on additional data to all the unilateral close
messages we send to subscribers. This new data is the CommitSet, or the
set of valid commitments at channel closure time. This new information
will be used by the channel arb in an upcoming commit to ensure it will
cancel back HTLCs in the case of split commitment state.
Finally, we start to thread through an optional *CommitSet to the
advanceState method. This additional information will give the channel
arb addition information it needs to ensure it properly cancels back
HTLCs that are about to time out or may time out depending on which
commitment is played.
Within the htlcswitch pakage, we modify the `SignNextCommitment` method
to return the new set of pending HTLCs for the remote party's commitment
transaction and `ReceiveRevocation` to return the latest set of
commitment transactions on the remote party's commitment as well. This
is a preparatory change which is part of a larger change to address a
lingering TODO in the cnct.
Additionally, rather than just send of the set of HTLCs after the we
revoke, we'll also send of the set of HTLCs after the remote party
revokes, and we create a pending commitment state for it.
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 the final step in making the link unaware of invoices. It
now purely offers the htlc to the invoice registry and follows
instructions from the invoice registry about how and when to respond to
the htlc.
The change also fixes a bug where upon restart, hodl htlcs were
subjected to the invoice minimum cltv delta requirement again. If the
block height has increased in the mean while, the htlc would be canceled
back.
Furthermore the invoice registry interaction is aligned between link and
contract resolvers.
This commit isolates preimages of forwarded htlcs from invoice
preimages. The reason to do this is to prevent the incoming contest
resolver from settling exit hop htlcs for which the invoice isn't marked
as settled.
The former tryApplyPreimage function silently ignored invalid preimages.
This could mask potential bugs. This commit makes the logic stricter and
generates an error in case an unexpected mismatch occurs.
New behaviour of the chain notifier to always send the current block
immediately after registration takes away the need to make a separate
GetBestBlock call on ChainIO.
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.
One of the first things the incoming contest resolver does is checking
if the preimage is available and if it is, convert itself into a success
resolver.
This behaviour makes it unnecessary to already determine earlier in the
process whether an incoming contest or a success resolver is needed.
By having all incoming htlcs go through the incoming contest resolver,
the number of execution paths is reduced and it becomes easier to
ascertain that the implemented logic is correct.
The only functional change in this commit is that a forwarded htlc for
which is the preimage is known, is no longer settled when the htlc is
already expired. Previously a success resolver would be instantiated
directly, skipping the expiry height check.
This created a risk that the success resolver would never finish,
because an expired htlc could already have been swept by the remote
party and there is no detection of this remote spend in the success
resolver currently.
With the new change, the general direction that an expired htlc
shouldn't be settled and instead given up on is implemented more
consistently.
This commit prepares for fixing edges cases related to hodl
invoice on-chain resolution.
In this commit, we modify the way we detect local force closes. Before
this commit, we would directly check the broadcast commitment's txid
against what we know to be our best local commitment. In the case of DLP
recovery from an SCB, it's possible that the user force closed, _then_
attempted to recover their channels. As a result, we need to check the
outputs directly in order to also handle this rare, but
possible recovery scenario.
The new detection method uses the outputs to detect if it's a local
commitment or not. Based on the state number, we'll re-derive the
expected scripts, and check to see if they're on the commitment. If not,
then we know it's a remote force close. A new test has been added to
exercise this new behavior, ensuring we catch local closes where we have
and don't have a direct output.
In this commit, we speed up the `TestChainWatcherDataLossProtect`
_considerably_ by enumerating relevant tests using table driven tests
rather than generating random tests via the `testing/quick` package.
Each of these test cases are also run in parallel bringing down the
execution time of this test from a few minutes, to a few seconds.
This commit adds logging of the reason to go to chain for a channel.
This can help users to find out the reason why a channels forced closed.
To get all go to chain reasons, an optimization to break early is
removed. This optimization was not significant, because the normal flow
already examined all htlcs. In the exceptional case where we need to go
to chain, it does not weigh up against logging all go to chain reasons.
This commits exposes the various parameters around going to chain and
accepting htlcs in a clear way.
In addition to this, it reverts those parameters to what they were
before the merge of commit d1076271456bdab1625ea6b52b93ca3e1bd9aed9.
