Due to a recent change within the codebase to return estimated fee rates
in sat/kw, this commit ensures that we use this fee rate properly by
calculing a transaction's fees using its weight. This includes all of
the different transactions that are created within lnd (funding, sweeps,
etc.). On-chain transactions still rely on a sat/vbyte fee rate since it's
required by btcwallet.
In this commit, we modify our FeeEstimator interface to return an
estimated fee rate in sat/kw. Recently, due to low fees on the network,
users have been experiencing failures broadcasting transactions due to
not meeting specific fee requirements. This was happening more often
than not, as the estimated fee returned by backend nodes (bitcoind and
btcd) only takes into account vbytes, rather than weight. The fees
returned are also expressed in sat/kb, so we must take care that we do
not lose precision while converting to sat/kw. In the event that this
happens, a fee floor of 253 sat/kw has been added. This fee rate
originates from bitcoind rounding up the conversion from weight to
vbytes.
In this commit, we introduce a nice optimization with regards to lnd's
interaction with a bitcoind backend. Within lnd, we currently have three
different subsystems responsible for watching the chain: chainntnfs,
lnwallet, and routing/chainview. Each of these subsystems has an active
RPC and ZMQ connection to the underlying bitcoind node. This would incur
a toll on the underlying bitcoind node and would cause us to miss ZMQ
events, which are crucial to lnd. We remedy this issue by sharing the
same connection to a bitcoind node between the different clients within
lnd.
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
This commit moves the responsibility for publishing the funding tx to
the network from the wallet to the funding manager. This is done to
distinguish the failure of completing the reservation within the wallet
and failure of publishing the transaction.
Earlier we could fail to broadcast the transaction, which would cause us
to fail the funding flow. This is not something we can do directly,
since the CompeteReservation call will mark the channel IsPending in the
databas.e
In this commit, we correct our size estimates for to-local scripts,
which are used on the commitment transaction and the htlc
success/timeout transactions. There have been observed cases of
transactions getting stuck because our estimates were too low, and cause
the transactions to not be relayed.
Our previous estimate for the commitment to-local script was derived
from an older version of the script. Though the estimate is greater than
the actual size, this has been updated with the current estimate of 79
bytes.
This estimates makes the assumption that CSV delays will be at most
4 bytes when serialized. Since this value is expressed in relative block
heights, this should be more than sufficient for our needs, even though
the maximum possible size for the little-endian int64 is 9 bytes (plus
an OP_DATA).
The other correction is to use the ToLocalScriptSize as our estimate for
htlc timeout/success scripts, as they are the same script. Previously,
our estimate was derived from the proper script, though we were 6 bytes
shy of the new to-local estimate, since we counted the csv_delay as 1
byte, and missed some other OP_DATAs.
All derived estimates have been updating depending on the new and
improved ToLocalScriptSize estimate, and fix some estimates that did not
include the witness length in the estimate.
Finally, we correct some weight miscalculations in:
- AcceptedHtlcTimeoutWitnessSize: missing data push lengths
- OfferedHtlcSuccessWitnessSize: extra 73 byte sig, missing data push lengths
- OfferedHtlcPenaltyWitnessSize: missing 33 byte pubkey
Makes the helper methods for constructing witness script
hash and to-local outputs. This will allow watchtowers to
import and reuse this logic when sweeping outputs.
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 adds a test which will restore a channel from an OpenChannel
struct at various stages of the state transation cycle, ensuring the
HTLC local and remote add heights are restored properly.
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 add a series of additional balance assertions to
ensure that the balance of the two channels at each stage match up with
our expectations. Additionally, we also fix a bug at the end of the test
which would result in Alice accidentally overdrawing her balance in the
channel. The issue was that the test attempted to settle HTLCs that
weren't yet fully locked in. We fix this by adding an additional state
transition before settling the final set of HTLCs.
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.
This commit adds a test that runs through a scenario where an HTLC is
added then failed, making sure the update logs are properly restored at
any point during the process.
This commit adds a test ensuring that the fix applied in the previous
commit works as expected. The test exercises the scenario where the
HTLCs on the local, remote and pending remote commitment differ, and we
attempt to restore the update logs. We now check that in this case the
logs before and after restart are equivalent.
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.
In this commit, we fix an issue where sometimes transactions wouldn't
provide enough of a fee to be relayed by the backend node. This would
especially cause issues when sweeping outputs after a contract breach,
etc.
Now, we'll fetch the minimum relay fee from the backend node and ensure
it is set as a lower bound if the estimated fee ends up dipping below
it.
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.
In this commit, we modify the NewUnilateralCloseSummary to be able to
distinguish between a unilateral closure using the lowest+highest
commitment the remote party possesses. Before this commit, if the remote
party broadcast their highest commitment, when they have a lower
unrevoked commitment, then this function would fail to find the proper
output, leaving funds on the chain.
To fix this, it's now the duty of the caller to pass remotePendingCommit
with the proper value. The caller should use the lowest unrevoked
commitment, and the height hint of the broadcast commitment to discern
if this is a pending commitment or not.
In this commit, we move a set of useful functions for testing channels
into a new file. The old createTestChannels has been improved as it will
now properly set the height hint on the first created commitments, and
also no longer accepts any arguments as the revocation window no longer
exists.
This commit changes the bool `IsBorked` in OpenChannel to a `ChanStatus`
struct, of type ChannelStatus. This is used to indicated that a channel
that is technically still open, is either borked, or has had a
commitment broadcasted, but is not confirmed on-chain yet.
The ChannelStatus type has the value 1 for the status Borked, meaning it
is backwards compatible with the old database format.
This commit renames ForceCloseSummary to LocalForceCloseSummary, and
adds a new method NewLocalForceCloseSummary that can be used to derive a
LocalForceCloseSummary if our commitment transaction gets confirmed
in-chain. It is meant to accompany the NewUnilateralCloseSummary method,
which is used for the same purpose in the event of a remote commitment
being seen in-chain.
In this commit, we fix an existing bug in the NewBreachRetribution
method. Rather than creating the slice to the proper length, we instead
now create it to the proper _capacity_. As we'll now properly filter out
any dust HTLCs, before this commit, even if no HTLCs were added, then
the slice would still have a full length, meaning callers could actually
interact with _blank_ HtlcRetribution structs.
The fix is simple: create the slice with the proper capacity, and append
to the end of it.
In this commit, we fix an existing within lnd. Before this commit,
within NewBreachRetribution the order of the keys when generating the
sender HTLC script was incorrect. As in this case, the remote party is
the sender, their key should be first. However, the order was swapped,
meaning that at breach time, our transaction would be rejected as it had
the incorrect witness script.
The fix is simple: swap the ordering of the keys. After this commit, the
test extension added in the prior commit now passes.
In this commit we add a new error: InvalidHtlcSigError. This error will
be returned when we're unable to validate an HTLC signature sent by the
remote party. This will allow other nodes to more easily debug _why_ the
signature was rejected.
In this commit we add a new command line option (and a sane default) to
allow users to specify the *smallest* inbound channel that they'll
accept. Having a higher-ish limit lets users limit their channels, and
also avoid a series of very low value "spam" channels.
The new option is --minchansize, and expressed in satoshis. If we
receive an inbound channel request for a value smaller than this, then
we'll immediately reject it.
In this commit, we add an additional check within CreateCommitTx to
ensure that we will never create or accept a commitment transaction that
wasn't valid by consensus. To enforce this check, we use the
blockchain.CheckTransactionSanity method.
In this commit, we fix an existing rounding related bug in the codebase.
The RPC interface for btcd and bitcoind return values in BTC rather than
in satoshis. So in several places, we're forced to convert ourselves
manually. The existing logic attempted to do this, but didn't properly
account for rounding. As a result, our values can be off due to not
rounding incorrectly.
The fix for this is easy: simply properly use btcutil.NewAmount
everywhere which does rounding properly.
Fixes#939.
This commit adds a check that will make LightningChannel reject a
received commitment if it is accompanied with too many HTLC signatures.
This enforces the requirement in BOLT-2, saying:
if num_htlcs is not equal to the number of HTLC outputs in the local commitment transaction:
* MUST fail the channel.
A test exercising the behaviour is added.
