funding: create new AuxFundingController interface

In this commit, we make a new `AuxFundingController` interface capable of processing messages off the wire. In addition, we can use it to abstract away details w.r.t how we obtain a `AuxFundingDesc` for a given channel.

We'll now use this whenever we get a channel funding request, to make sure we pass along the custom state that a channel may require.
This commit is contained in:
Olaoluwa Osuntokun 2024-04-04 17:27:20 -07:00 committed by Oliver Gugger
parent 54bbc25d9a
commit 2f6e7ef191
No known key found for this signature in database
GPG key ID: 8E4256593F177720
2 changed files with 116 additions and 0 deletions

82
funding/aux_funding.go Normal file
View file

@ -0,0 +1,82 @@
package funding
import (
"github.com/btcsuite/btcd/chaincfg/chainhash"
"github.com/lightningnetwork/lnd/channeldb"
"github.com/lightningnetwork/lnd/fn"
"github.com/lightningnetwork/lnd/lnwallet"
"github.com/lightningnetwork/lnd/protofsm"
)
// AuxFundingController permits the implementation of the funding of custom
// channels types. The controller serves as a MsgEndpoint which allows it to
// intercept custom messages, or even the regular funding messages. The
// controller might also pass along an aux funding desc based on an existing
// pending channel ID.
type AuxFundingController interface {
// MsgEndpoint is the embedded interface that signals that the funding
// controller is also a message endpoint. This'll allow it to handle
// custom messages specific to the funding type.
protofsm.MsgEndpoint
// DescFromPendingChanID takes a pending channel ID, that may already be
// known due to prior custom channel messages, and maybe returns an aux
// funding desc which can be used to modify how a channel is funded.
DescFromPendingChanID(pid PendingChanID,
openChan *channeldb.OpenChannel,
localKeyRing, remoteKeyRing lnwallet.CommitmentKeyRing,
initiator bool) (fn.Option[lnwallet.AuxFundingDesc], error)
// DeriveTapscriptRoot takes a pending channel ID and maybe returns a
// tapscript root that should be used when creating any MuSig2 sessions
// for a channel.
DeriveTapscriptRoot(PendingChanID) (fn.Option[chainhash.Hash], error)
// ChannelReady is called when a channel has been fully opened (multiple
// confirmations) and is ready to be used. This can be used to perform
// any final setup or cleanup.
ChannelReady(openChan *channeldb.OpenChannel) error
// ChannelFinalized is called when a channel has been fully finalized.
// In this state, we've received the commitment sig from the remote
// party, so we are safe to broadcast the funding transaction.
ChannelFinalized(PendingChanID) error
}
// descFromPendingChanID takes a pending channel ID, that may already be known
// due to prior custom channel messages, and maybe returns an aux funding desc
// which can be used to modify how a channel is funded.
func descFromPendingChanID(controller fn.Option[AuxFundingController],
chanID PendingChanID, openChan *channeldb.OpenChannel,
localKeyRing, remoteKeyRing lnwallet.CommitmentKeyRing,
initiator bool) (fn.Option[lnwallet.AuxFundingDesc], error) {
var result fn.Option[lnwallet.AuxFundingDesc]
mapErr := fn.MapOptionZ(controller, func(c AuxFundingController) error {
var err error
result, err = c.DescFromPendingChanID(
chanID, openChan, localKeyRing, remoteKeyRing,
initiator,
)
return err
})
return result, mapErr
}
// deriveTapscriptRoot takes a pending channel ID and maybe returns a
// tapscript root that should be used when creating any MuSig2 sessions for a
// channel.
func deriveTapscriptRoot(controller fn.Option[AuxFundingController],
chanID PendingChanID) (fn.Option[chainhash.Hash], error) {
var result fn.Option[chainhash.Hash]
mapErr := fn.MapOptionZ(controller, func(c AuxFundingController) error {
var err error
result, err = c.DeriveTapscriptRoot(chanID)
return err
})
return result, mapErr
}

View file

@ -543,6 +543,12 @@ type Config struct {
// AuxLeafStore is an optional store that can be used to store auxiliary
// leaves for certain custom channel types.
AuxLeafStore fn.Option[lnwallet.AuxLeafStore]
// AuxFundingController is an optional controller that can be used to
// modify the way we handle certain custom channel types. It's also
// able to automatically handle new custom protocol messages related to
// the funding process.
AuxFundingController fn.Option[AuxFundingController]
}
// Manager acts as an orchestrator/bridge between the wallet's
@ -1613,6 +1619,18 @@ func (f *Manager) fundeeProcessOpenChannel(peer lnpeer.Peer,
return
}
// At this point, if we have an AuxFundingController active, we'll
// check to see if we have a special tapscript root to use in our
// MuSig funding output.
tapscriptRoot, err := deriveTapscriptRoot(
f.cfg.AuxFundingController, msg.PendingChannelID,
)
if err != nil {
err = fmt.Errorf("error deriving tapscript root: %w", err)
log.Error(err)
f.failFundingFlow(peer, cid, err)
}
req := &lnwallet.InitFundingReserveMsg{
ChainHash: &msg.ChainHash,
PendingChanID: msg.PendingChannelID,
@ -1629,6 +1647,7 @@ func (f *Manager) fundeeProcessOpenChannel(peer lnpeer.Peer,
ZeroConf: zeroConf,
OptionScidAlias: scid,
ScidAliasFeature: scidFeatureVal,
TapscriptRoot: tapscriptRoot,
}
reservation, err := f.cfg.Wallet.InitChannelReservation(req)
@ -4603,6 +4622,20 @@ func (f *Manager) handleInitFundingMsg(msg *InitFundingMsg) {
scidFeatureVal = true
}
// At this point, if we have an AuxFundingController active, we'll check
// to see if we have a special tapscript root to use in our MuSig2
// funding output.
tapscriptRoot, err := deriveTapscriptRoot(
f.cfg.AuxFundingController, chanID,
)
if err != nil {
err = fmt.Errorf("error deriving tapscript root: %w", err)
log.Error(err)
msg.Err <- err
return
}
req := &lnwallet.InitFundingReserveMsg{
ChainHash: &msg.ChainHash,
PendingChanID: chanID,
@ -4626,6 +4659,7 @@ func (f *Manager) handleInitFundingMsg(msg *InitFundingMsg) {
OptionScidAlias: scid,
ScidAliasFeature: scidFeatureVal,
Memo: msg.Memo,
TapscriptRoot: tapscriptRoot,
}
reservation, err := f.cfg.Wallet.InitChannelReservation(req)