Incoming htlcs that are timed out or failed (invalid htlc or invoice
condition not met), save a single on chain resolution because we don't
need to take any actions on them ourselves (we don't need to worry
about 2 stage claims since this is the success path for our peer).
Our current set of reports contain much of the information we will
need to persist contract resolutions. We add a function to create
resolver reports from our exiting set of resolutions.
To allow us to write the outcome of our resolver to disk, we add
optional resolver reports to the CheckPoint function. Variadic params
are used because some checkpoints may have no reports (when the resolver
is not yet complete) and some may have two (in the case of a two stage
resolution).
Previously it wasn't possible to store a preimage in the invoice
database and signal that a payment should not be settled right away. The
only way to hold a payment was to insert the magic UnknownPreimage value
in the invoice database. This commit introduces a distinct flag to
signal that an invoice is a hold invoice and thereby allows the preimage
to be present in the database already.
Preparation for (key send) hodl invoices for which we already know the
preimage.
Add label parameter to PublishTransaction in WalletController
interface. A labels package is added to store generic labels that are
used for the different types of transactions that are published by lnd.
To keep commit size down, the two endpoints that require a label
parameter be passed down have a todo added, which will be removed in
subsequent commits.
This adds a test to the commit sweeper resolver to ensure it behaves
properly if the local node breaches a channel.
In this situation the remote party is expected to sweep the breached
output to itself and therefore the local party won't be able to recover
any funds.
This fixes an issue where the contract court could leave a completely
swept commit tx unresolved if it was swept by the remote party.
This could happen if (our) commit tx just published was actually a
previously revoked state, in which case the remote party would claim the
funds via a justice transaction.
This manifested itself in the testRevokedCloseRetribution integration
test where at the end of the test Bob was left with a pending channel
that never resolved itself.
In this commit, we add some additional logging of the commitments at
play when we detect a channel closure on-chain. This should help to
debug things more in the future as we don't log the full commitments
anywhere. We also now also print the type of commitment as well, as a
follow up from the recent anchor outputs work. In the near future, as we
implement a dynamic commitments update protocol, always logging the
commitment type as well will likely be useful for debugging purposes.
Sweeping anchors and being able to bump the fee was already added in a
previous commit. This commit extends anchor sweeping with an anchor
resolver object that becomes active after the commitment tx confirms.
At that point, the anchors do not serve the purpose of getting the
commitment tranaction confirmed anymore. It is however still possible to
reclaim some of their value if using a low fee rate.
Preparation for anchor resolver. The recovered anchor amount should
still be included in the pending channel report even after it has been
resolved.
This also fixes an existing bug that in some cases caused the recovered
amount from an htlc resolver not to be included in the total.
Start anchor sweep attempts immediately after the commitment transaction
has been published. This makes the anchor known to the sweeper and
allows the user to bump the fee on it to get their commitment
transaction confirmed in case the fee committed too is insufficient for
timely confirmation.
Prior to this change, the trigger height for closed channels was set to
the current best block height. As this height is in some cases used as a
height hint, the spend may have been missed.
We use the fact that we can tell whether the commit is local or remote
by inspecting the witness script. We cannot use the maturity delay
anymore, as we can have delayed to_remote outputs also now.
Co-authored-by: Joost Jager <joost.jager@gmail.com>
This commit adds two new channel statuses which indicate the party that
initatited closing the channel. These statuses are set in conjunction
with the existing commit broadcast status so that we do not need to
migrate existing logic to handle multiple types of closes. This status
is set for locally initiated force closes in this commit because they
follow a similar pattern to cooparative closes, marking the commitment
broadcast then proceeding with tx broadcast. Remote force closes are
added in the following commit, as they are handled differently.
This commit enables the user to specify he is not interested in
automatically close channels with pending payments that their
corresponding htlcs have timed-out.
By requiring a configurable grace period uptime of our node
before closing such channels, we give a chance to the other node to
properly cancel the htlc and avoid unnecessary on-chain transaction.
In mobile it is very important for the user experience as otherwise
channels will be force closed more frequently.
This commit repalces the htlcResolution struct with an interface.
This interface is implemeted by failure, settle and accept resolution
structs. Only settles and fails are exported because the existing
code that handles htlc resolutions uses a nil resolution to indicate
that a htlc was accepted. The accept resolution is used internally
to report on the resolution result of the accepted htlc, but a nil
resolution is surfaced. Further refactoring of all the functions
that call NotifyExitHopHtlc to handle a htlc accept case (rather than
having a nil check) is required.
This commit changes the shouldGoOnChain signature to get the htlc
as parameter. I will allow the function to take decisions based on
whether the htlc is Incoming or Outgoing.
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.
We abstract away how keys are generated for the different channel types
types (currently tweak(less)).
Intention is that more of the logic that is unique for each commitment
type lives in commitment.go, making the channel state machine oblivious
to the keys and outputs being created on the commitment tx for a given
channel state.
This commit moves handling of invoice not found
errors into NotifyExitHopHtlc and exposes a
resolution result to the calling functions. The
intention of this change is to make calling
functions as naive of the invoice registry's
mechanics as possible.
When NotifyExitHopHtlc is called and an invoice
is not found, calling functions can take action
based on the HtlcResolution's InvoiceNotFound
outcome rather than having to add a special error
check on every call to handle the error.
This commit adds the resolution result obtained
while updating an invoice in the registry to
htlcResolution. The field can be used by calling
functions to determine the outcome of the
update and act appropriately.
This commit adds a constructor for HtlcResolution creation
to enforce provision of all relevant values when an
event is created. A custom construstor which also takes
a preimage is added for settle events.
This commit renames HodlEvent to HtlcResolution
to better reflect the fact that the struct is
only used for htlc settles and cancels, and that
it is not specifically used for hodl invoices.
In this commit, we export the `ResolveContract` method as it's useful as
a way to manually remove active contracts from the chain and channel
arbitrator. Along the way, we also update the method to also attempt to
stop the channel arb if it exists. This allows an external party to
remove all state with a single call. Before this commit, it was assumed
that this method was only called by the channel arb itself, when it was
already on the way to exiting after all contracts were fully resolved.
We also add a set of unit tests to exercise the intended behavior as
this method is now public.
The channel arbitrator no longer passes the direct commitment output to
the nursery for incubation. Instead the resolver itself will await the
csv lock if any.
The reason to change this now is to prevent having to deal with the
(legacy) nursery code for a planned anchor outputs related change to the
commit sweep resolver (also csv lock to_remote).
It is no problem if there are any lingering incubating outputs at the
time of upgrade. This just means that the output will be offered twice
to the sweeper and this doesn't hurt.
With the introduction of additional payload fields for mpp, it becomes
a necessity to have their values available in the on-chain resolution
flow. The incoming contest resolver notifies the invoice registry of the
arrival of a payment and needs to supply all parameters for the registry
to validate the htlc.
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 fix a bug that would prevent users that had
unresolved contracts at the time of update from starting their nodes.
Before we added the conf commit set, the information needed to
supplement the resolvers was found in the chain action map. As a result,
if the conf commit set is nil, then we also need to check this legacy
data to ensure that we can supplement the resolvers to the best of our
ability based on the available data.
Fixes#3549.
In this commit, we consolidate the number of areas where we derive our
commitment keys. Before this commit, the `isOurCommitment` function in
the chain watcher used a custom routine to derive the expected
scripts/keys for our commitment at that height. With the recent changes,
we now have additional logic in `DeriveCommitmentKeys` that wasn't
copied over to this area. As a result, the prior logic would erroneously
detect if it was our commitment that had hit the chain or not.
In this commit, we remove the old custom code, and use
`DeriveCommitmentKeys` wihtin the chain watcher as well. This ensures
that we only need to maintain the key derivation code in a single place,
preventing future bugs of this nature.
In this commit, we update the logic in the `chainWatcher` to no longer
wait until the DLP point has been populated in the database before we
dispatch the force close summary to any registered clients. Instead, we
can sweep immediately, as we have all the information we need to sweep
the funds (just our key).
In this commit, we update the `commitSweepResolver` to be aware of
tweakless commitments. We'll now use the new behavior of the uni close
summary (leaving out the single tweak) to detect if we're dealing with a
new, or modern commitment. Depending on the commitment type, we'll then
set the witness type accordingly so we can generate the proper signature
within the sweeper.
In this commit, we update the funding workflow to be aware of the new
channel type that doesn't tweak the remote party's output within the
non-delay script on their commitment transaction. To do this, we now
allow the caller of `InnitChannelReservation` to signal if they want the
old or new (tweakless) commitment style.
The funding tests are also updated to test both funding variants, as
we'll still need to understand the legacy format for older nodes.
In this commit, we fix an existing bug in the package, causing
resolutions to be restarted without their required supplementary
information. This can happen if a distinct HTLC set gets confirmed
compared to the HTLCs that we may have had our commitment at time of
close. Due to this bug, on restart certain HTLCS would be rejected as
they would present their state to the invoice registry, but be rejected
due to checks such as amount value.
To fix this, we'll now pass in the set of confirmed HTLCs into the
resolvers when we re-launch them, giving us access to all the
information we need to supplement the HTLCS.
We also add a new test that ensures that the proper fields of a resolver
are set after a restart.
In this commit, we create a new channel arb test context struct as the
current `createTestChannelArbitrator` has several return parameters, and
upcoming changes will likely at first glance need to add one or more
additional parameters. Rather than extend the existing set of return
parameters, we opt to instead create this struct that wraps the existing
state.
Along the way we add several new utility methods to this context, and
use them in the existing tests where applicable:
* `AssertStateTransitions`
* `AssertState`
* `Restart`
* `CleanUp`
Before publishing the close tx to the network and commit to the
StateCommitmentBroadcasted state, we mark the commitment as broadcasted
and store it to the db. This ensures it will get re-published on startup
if we go down.
TestChainArbitratorRepulishCommitment testst that the chain arbitrator
will republish closing transactions for channels marked
CommitementBroadcast in the database at startup.
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 d107627145.
In this commit, we modify the `closeObserver` to fast path the DLP
dispatch case if we detect that the channel has been restored. We do
this as otherwise, we may inadvertently enter one of the other cases
erroneously, causing us to now properly look up their dlp commitment
point.
In this commit, we modify the main `closeObserver` dispatch loop to only
look for the local force close if we didn't recover the channel. We do
this, as for a recovered channel, it isn't possible for us to force
close from a recovered channel.
The multiplier doesn't make sense because funds may be equally at risk
by failing to broadcast to chain regardless of whether the HTLC is a
redeem or a timeout.
