This commit aims to address a flaw in our anchor reserve enforcement
logic in which an inbound "legacy" channel (i.e. a channel with a
commitment type that precedes anchors) would be rejected by the
recipient if they have at least one opened channel using the anchors
commitment type and do not have enough on-chain funds to meet the
anchors reserve.
Otherwise, we would get non-standard txn's and fail to broadcast
them when cooperatively closing a channel. This wouldn't affect
funds security as no HTLCs would be active to steal. This is just
a safety measure as we should only generate standard txn's.
Since private channels (most likely) won't be used for routing other
than as last hop, they bear a smaller risk that we must quickly force
close them in order to resolve a HTLC up/downstream.
In the case where it actually has to be force to resolve a payment (if
it is the first/last hop on a routed payment), we can assume that the
router will have UTXOs available from the reserved value from the
incoming public channel.
We cap the maximum value we'll reserve for anchor channel fee bumping at
10 times the per-channel amount such that nodes with a high number of
channels don't have to keep around a very large amount for the unlikely
scanario that they all close at the same time.
This commit adds a RevocationKeyLocator field to the OpenChannel
struct so that the SCB derivation doesn't have to brute-force the
sha chain root key and match the public key. ECDH derivation is now
used to derive the key instead of regular private key derivation a
la DerivePrivKey. The legacy can still be used to recover old
channels.
In this commit, we make a new wrapper method around the internal
`WalletController` method to ensure it holds the coin select mutex while
the balance is being computed.
In case the funding manager detects that a funding flow is requested
to be executed with the help of a PsbtIntent, the normal channel
negotiation with the remote peer is interrupted, as soon as the
accept_channel message was received. With the remote peer's funding
multisig key and our local key, we can derive the funding output
script and its address. This is enough to start the PSBT funding
and signing process which the user will do externally to the daemon.
In this commit, we make the internal channel funding flow aware of
frozen channels. We also update the testSingleFunderReservationWorkflow
method to ensure that the created channels have the proper type bit set.
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.
Instead of passing delays and dustlimits separately, we pass the correct
channel config to CreateCommitTx from the POV of the local party that
owns the commit tx.
To make it more clear which commitment we are actually creating, we
rename variables to denote local and remote, to prepare for the case
when both outputs might be delayed.
In this commit, we implement the currently defined transition methods
for the new `FundingStateStep` method. At this point, we're now able to
serve the "responder" of the externally initiated channel funding flow
by being able to register and cancel a funding flow according to its
expected pending channel ID.
This commit gets upfront shutdown scripts from openchannel and
acceptchannel wire messages sent from our peer and sets upfront
shutdown scripts in our open and accept channel messages when
the remote peer supports option upfront shutdown and we have
the feature enabled.
In this commit, we fix a long standing bug within the newly created
`verifyFundingInputs` method. Before this commit, the method would
attempt to derive the pkScript by looking at the last items on the
witness stack, and making a p2wsh output script from that. This is
incorrect as typically non of these scripts will actually be p2wsh, and
instead will be p2wkh. We fix this by using the newly available
`txscript.ComputePkScript` method to derive the proper pkScript.
This resolves an issue w.r.t passing incorrect arguments for all
backends, but an issue still stands for the neutrino backend. As is, we
pass a height hint of zero into the `GetUtxo` method call. With the way
the current utxo scanner is set up for neutrino, this'll cause it to
never find the UTXO, as it takes the height hint as a UTXO birth height,
rather than a lower bound of the birth of the UTXO.
In this commit, we add a new method `RegisterFundingIntent` that allows
a caller to "inject" a pre-populated chanfunding.Intent into a funding
workflow. As an example, if we've already agreed upon the "shape" of the
funding output _outside_ the protocol, then we can use this to pass down
the details of the output, then leverage the normal wire protocol to
carry out the remainder of the funding flow.
In this commit, we start to thread the pending channel ID from wire
protocol all the way down into the reservation context. This change will
allow negotiation to take place _outside_ the protocol that may result
in a particular chanfunding.Assembler being dispatched.
In this commit, we make the wallet aware of the second type of funding
intent: the ShimIntent. If we have one of these, then we don't need to
construct the funding transaction, and can instead just obtain the
outpoint directly from it.
In this commit, we begin to integrate the new channel funding package
into the existing codebase. With this set of changes, we'll no longer
construct and sign the funding transaction within this package, instead
delegating it to the new chanfunding package. We use the new
chanfunding.WalletAssembler to carry out all channel funding, providing
it with an implementation of all its interfaces backed by the wallet.
In this commit, we make an incremental change to move the existing coin
selection code into a new chanfunding package. In later commits, this
package will grow to serve all the lower level channel funding needs in
the daemon.
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 use the recently added `chanvalidate` package to
verify channels once they have been confirmed in the funding manager. We
expose a new method on the `LightningWallet` struct: `ValidateChannels`
which calls the new shared 1st party verification code.
After the channel is fully confirmed in the funding manager, we'll now
use this newly exposed method to handle all validation. As a result, we
can remove the existing validation code in the funding manager, and rely
on the new code in isolation.
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 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 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.
This commit adds a SubtractFees option to the funding request, letting
the caller specify that the fees should be deducted from the funding
amount. This paves the way for letting the funding manager spend up to a
given amount when creating a channel, like the rest of the funds in the
wallet.
This makes the method independent of the ChannelContribution struct.
We also add a function closure to the return of selectCoinsAndChange,
that let is unlock the selected output in case of error.
