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 convert the existing `channeldb.ChannelType` type
into a _bit field_. This doesn't require us to change the current
serialization or interpretation or the type as it is, since all the
current defined values us a distinct bit. This PR lays the ground work
for any future changes that may introduce new channel types (like anchor
outputs), and also any changes that may modify the existing invariants
around channels (if we're the initiator, we always have the funding
transaction).
Without this, it was possible for a combination of our balance and max
fee allocation to result in a fee rate below the fee floor causing the
remote party to reject the update and close the channel.
In this commit, we move to make a full deep copy of the commitment
transaction in `getSignedCommitTx` to ensure that we don't mutate the
commitment on disk, possibly resulting in a "hot commitment".
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 brar logic in the channel state machine,
and also the brar itself to be aware of the new commitment format.
Similar to the unilateral close summary, we'll now blank out the
SingleTweak field in `NewBreachRetribution` if it's a tweakless
commitment. The brar will then use this to properly identify the
commitment type, to ensure we use the proper witness generation function
when we're handling our own breach.
In this commit, we update the channel state machine to be aware of
tweakless commits. In several areas, we'll now check the channel's type
to see if it's `SingleFunderTweakless`. If so, then we'll opt to use the
remote party's non-delay based point directly in the script, skipping
any additional cryptographic operations. Along the way we move the
`validateCommitmentSanity` method to be defined _before_ it's used as is
cutomary within the codebase.
Notably, within the `NewUnilateralCloseSummary` method, we'll now _blank
out_ the `SingleTweak` value if the commitment is tweakless. This
indicates to callers the witness type they should map to, as the value
isn't needed at all any longer when sweeping a non-delay output.
We also update the signing+verification tests to also test that we're
able to properly generate a valid witness for the new tweakless
commitment format.
Instead of marking the database state when processing the channel
reestablishment message, we wait for the result of this processing to
arrive in the link, and mark it accordingly in the database here.
We do this move the logic determining whether we should force close the
channel or not, and what state to mark it in the DB, to the same place,
as these need to be consistent.
This commit converts the ErrCommitSyncLocalDataLoss error into a struct,
that also holds the received last unrevoked commit point from the remote
party.
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.
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.
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.
In this commit, we modify the `ChanSyncMsg` to send an invalid
commitment secret in `ChanSyncMsg`. We do this in order to force the
remote party to force close off-chain, if we're restoring a channel from
scratch and we never had any state updates within the channel. We need
to do this, as otherwise the remote party will think we can resume as
they're able to verify their own commit secret for state zero.
In this commit, we set a default max HTLC in the forwarding
policies of newly open channels.
The ForwardingPolicy's MaxHTLC field (added in this commit)
will later be used to decide whether an HTLC satisfies our policy before
forwarding it.
To ensure the ForwardingPolicy's MaxHTLC default matches the max HTLC
advertised in the ChannelUpdate sent out for this channel, we also add
a MaxPendingAmount() function to the lnwallet.Channel.
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.
To avoid more bugs slipping through where the logIndex is not set, we
panic to catch this. This was earlier done for Adds and the htlcCounter,
which did lead us to find the resulting retoration bug.
Earlier versions did not write the log index to disk for fee updates, so
they will be unset. To account for this we set them to to current update
log index.
In this commit, we ensure that if a channel is detected to have local
data loss, then we don't allow a force close attempt, as this may not be
possible, or cause us to play an invalid state.
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).
Instead of special casing the UpdateFee messages, we instead add them to
the update logs like any other HTLC update message. This lets us avoid
having to keep an extra set of variables to keep track of the fee
updates, and instead reuse the commit/ack logic used for other updates.
This fixes a bug where we would reset the pendingFeeUpdate variable
after signing our next commitment, which would make us calculate the new
fee incorrectly if the remote sent a commitment concurrently.
When restoring state logs, we also make sure to re-add any fee updates.
When compacting the update logs we remove any fee updates when they
remove height is passed. We do this since we'll assume fee updates are
added and removed at the same commit height, as they will apply for all
commitments following the fee update.
This commit adds conversion between the lnwire.UpdateFee message and the
new FeeUpdate PaymentDescriptor. We re-purpose the existing Amount field
in the PaymentDescriptor stuct to hold the feerate.
This commit adds a new updateType that can be used for
PaymentDescriptors: FeeUpdate. We repurpose the fields of the existing
PaymentDescriptor struct such that we can easily re-use the commit/ack
logic used for other update types also for fee 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.
In this commit, we fix an existing bug wherein we wouldn't set the short
channel ID for the close summary in the database in the case that the
remote party force closed. The fix is simple, ensure that within
NewUnilateralCloseSummary we properly set the short channel ID. A test
has also been added in this commit, which fails without the
modifications to lnwallet/channel.go.
Fixes#2072.
In this commit, we fix a slight bug by ensuring that the revocation info
at the final state of the channel, as well as the local chan config is
properly set within the channel close summary created within
NewUnilateralCloseSummary. Before this commit, for all cooperative close
transactions, this state would _only_ include the pubkey itself, which
in some cases may not be sufficient to re-derive the key if needed.
In this commit, we update the NewBreachRetribution method to include
pkScripts for htlc outputs. We do this now, as the breach arbiter will
need the raw pkScript when attempting to request spend notifications for
each HTLC.
In this commit, we export WitnessScriptHash and GenMultiSigScript as
external sub-systems may now need to use these methods in order to be
able to watch for confirmations based on the script of a transaction.
This commit adds a check for the LocalUnrevokedCommitPoint sent to us by
the remote during channel reestablishment, ensuring it is the same point
as they have previously sent us.
This commit enumerates the various error cases we can encounter when we
compare our remote commit chain to the view the remote communicates to us
via msg.NextLocalCommitHeight.
We now compare this height to our remote tail and tip height, returning
relevant error in case of a unrecoverable desync, and re-send a
commitment signature (including log updates) in case we owe one.
This commit enumerates the various error cases we can encounter when we
compare our local commit chain to the view the remote communicates to us
via msg.RemoteCommitTailHeight.
We now compare this height to our local tail height (note that there's
never a local "tip" at this point), returning relevant error in case of
a unrecoverable desync, and re-send a revocation in case we owe one.
This commit defines a few new errors that we can potentially encounter
during channel reestablishment:
* ErrInvalidLocalUnrevokedCommitPoint
* ErrCommitSyncLocalDataLoss
* ErrCommitSyncRemoteDataLoss
in addition to the already defined errors
* ErrInvalidLastCommitSecret
* ErrCannotSyncCommitChains
We check if the channel is FullySynced instead of comparing the local
and remote commit chain heights, as the heights might not be in sync.
Instead we call FullySynced which recently was modified to use compare
the message indexes instead, which is _should_ really be in sync between
the chains.
The test TestChanSyncOweRevocationAndCommitForceTransition is altered to
ensure the two chains at different heights before the test is started, to
trigger the case that would previously fail to resend the commitment
signature.
This commit fixes a bug which would cause the add heights of the HTLCs
in the update log to be set wrongly. At times, an add height could be
incorrecly set, leading to the HTLCs not being accounted for correctly
during evaluating the HTLC views. This was caused by the assumption that
if the HTLC was not on the pending remote commit, then it was locked in
on both the local and the remote commit, which is not always true.
Instead of making this assumption, we instead now inspect the three
commits: the local, remote and pending remote; and set the add heights
accordingly. This should ensure that HTLCs are subtracted from the
balances only when they are first added.
In this commit, we add a new index to the HTLC log. This new index is
meant to ensure that we don't attempt to modify and HTLC twice. An HTLC
modification is either a fail or a settle. This is the first in a series
of commits to fix an existing bug in the state machine that can cause a
panic if a remote node attempts to settle an HTLC twice.
In this commit, we add a precautionary assertion at the end of
createCommitmentTx. This assertion is meant to ensure that we don't
accept or propose a commitment transaction that attempts to send out
more than it was funded with.
In this commit, we move the check to CheckTransactionSanity into
createCommitmentTx. We do this as within wallet.go (during the funding
process) we actually end up calling this helper function twice, and also
moving it up until right when we create the fully commitment transaction
ensures we making our assertion against the final version.
This commit removes redundant HTLC restoring. We don't have to restore
outgoing HTLCs from the local commitment, as we _know_ they will always
be added to the remote commitment first. Also, when receiving
Settles/Fails, they will be removed from the local commitment first.
This way we can be sure that outgoing HTLCs found on the local
commitment always will be found on the remote commitment
Similarly we don't have to restore incoming HTLCs from the remote
commitment, as they will be added to the local commitment first.
This commit removes the stage during updateLog restoration where we
would attempt to restore incoming HLTCs from the pendingRemoteCommit, in
addition to update our log and htlc counter to reflect this state. The
reason we can safely remove this is to observe that a pending remote
commit is always created from a commitDiff which only contains updates
made by _us_, and thus only taken from the localUpdateLog. The same can
be said for the counters, when creating a commitDiff we'll always use
the remoteACKedIndex as the index into the remoteUpdateLog, meaning that
all potential updates will already be included in the remote commit that
has been ACKed.
remoteUpdateLog from localCommit
This commit fixes a bug within channel.go that would lead to the
content of the update logs and their indexes getting out of sync during
restores.
The scenario that could occur was that the localUpdateLog was initiated
with a log index taken from the localCommitment. Updates we send (which
are added to the localUpdateLog) will be added to the remote commitment
first. The problem happened when an update was sent and added to the
remote commitment, but not ACKed. Since it was not ACKed, we would not
add it to our local commitment. During a restart/restore we would init
the localUpdateLog with a height too low, such that when going through
the outgoing HTLCs on the remote commitment, we would restore an HTLC at
an index higher than our local log HTLC counter.
The symmetric change is done to the remoteUpdateLog.
This commit removes a faulty check we did to determine if the channel
commitments were fully synced. We assumed that if out local commitment
chain had a height higher than the remote, then we would have state
updates present in our chain but not in theirs, and owed a commitment.
However, there were cases where this wasn't true, and we would send a
new commitment even though we had no new updates to sign. This is a
protocol violation.
Now we don't longer check the heights to determine if we are fully
synced. A consequence of this is that we also need to check if we have
any pending fee updates that are nopt yet signed, as those are
considered non-empty updates.
This commit make us return an error in case a restored HTLC from a
pending remote commit has an index that is different from our local
update log index. It is appended with the assumption that these indexes
are the same, and if they are not we cannot really continue.
This commit adds a call to panic in case the HTLC we are looking for is
not found in the update log. It _should_ always be there, but we have
seen crashes resulting from it not being found. Since it will crash with
a nil pointer dereference below, we instead call panic giving us a bit
more information to work with.
