18016273007

Committed 25 Sep 2025 05:55PM UTC coverage: 54.653% (-12.0%) from 66.622%

Build # 18016273007

Build Type

Pull #10248

github

Committed by

web-flow

Commit Message

Merge 128443298 into b09b20c69

Pull Request Pull Request #10248: Enforce TLV when creating a Route

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67.67

/funding/manager.go

package funding

import (
        "bytes"
        "encoding/binary"
        "errors"
        "fmt"
        "io"
        "sync"
        "sync/atomic"
        "time"

        "github.com/btcsuite/btcd/blockchain"
        "github.com/btcsuite/btcd/btcec/v2"
        "github.com/btcsuite/btcd/btcec/v2/ecdsa"
        "github.com/btcsuite/btcd/btcec/v2/schnorr/musig2"
        "github.com/btcsuite/btcd/btcutil"
        "github.com/btcsuite/btcd/chaincfg/chainhash"
        "github.com/btcsuite/btcd/txscript"
        "github.com/btcsuite/btcd/wire"
        "github.com/lightningnetwork/lnd/chainntnfs"
        "github.com/lightningnetwork/lnd/chanacceptor"
        "github.com/lightningnetwork/lnd/channeldb"
        "github.com/lightningnetwork/lnd/discovery"
        "github.com/lightningnetwork/lnd/fn/v2"
        "github.com/lightningnetwork/lnd/graph"
        "github.com/lightningnetwork/lnd/graph/db/models"
        "github.com/lightningnetwork/lnd/input"
        "github.com/lightningnetwork/lnd/keychain"
        "github.com/lightningnetwork/lnd/labels"
        "github.com/lightningnetwork/lnd/lncfg"
        "github.com/lightningnetwork/lnd/lnpeer"
        "github.com/lightningnetwork/lnd/lnrpc"
        "github.com/lightningnetwork/lnd/lnutils"
        "github.com/lightningnetwork/lnd/lnwallet"
        "github.com/lightningnetwork/lnd/lnwallet/chainfee"
        "github.com/lightningnetwork/lnd/lnwallet/chanfunding"
        "github.com/lightningnetwork/lnd/lnwire"
        "golang.org/x/crypto/salsa20"
)

var (
        // byteOrder defines the endian-ness we use for encoding to and from
        // buffers.
        byteOrder = binary.BigEndian

        // checkPeerChannelReadyInterval is used when we are waiting for the
        // peer to send us ChannelReady. We will check every 1 second to see
        // if the message is received.
        //
        // NOTE: for itest, this value is changed to 10ms.
        checkPeerChannelReadyInterval = 1 * time.Second

        // errNoLocalNonce is returned when a local nonce is not found in the
        // expected TLV.
        errNoLocalNonce = fmt.Errorf("local nonce not found")

        // errNoPartialSig is returned when a partial sig is not found in the
        // expected TLV.
        errNoPartialSig = fmt.Errorf("partial sig not found")
)

// WriteOutpoint writes an outpoint to an io.Writer. This is not the same as
// the channeldb variant as this uses WriteVarBytes for the Hash.
func WriteOutpoint(w io.Writer, o *wire.OutPoint) error {
        scratch := make([]byte, 4)

        if err := wire.WriteVarBytes(w, 0, o.Hash[:]); err != nil {
                return err
        }

        byteOrder.PutUint32(scratch, o.Index)
        _, err := w.Write(scratch)
        return err
}

const (
        // MinBtcRemoteDelay is the minimum CSV delay we will require the remote
        // to use for its commitment transaction.
        MinBtcRemoteDelay uint16 = 144

        // MaxBtcRemoteDelay is the maximum CSV delay we will require the remote
        // to use for its commitment transaction.
        MaxBtcRemoteDelay uint16 = 2016

        // MinChanFundingSize is the smallest channel that we'll allow to be
        // created over the RPC interface.
        MinChanFundingSize = btcutil.Amount(20000)

        // MaxBtcFundingAmount is a soft-limit of the maximum channel size
        // currently accepted on the Bitcoin chain within the Lightning
        // Protocol. This limit is defined in BOLT-0002, and serves as an
        // initial precautionary limit while implementations are battle tested
        // in the real world.
        MaxBtcFundingAmount = btcutil.Amount(1<<24) - 1

        // MaxBtcFundingAmountWumbo is a soft-limit on the maximum size of wumbo
        // channels. This limit is 10 BTC and is the only thing standing between
        // you and limitless channel size (apart from 21 million cap).
        MaxBtcFundingAmountWumbo = btcutil.Amount(1000000000)

        msgBufferSize = 50

        // pendingChansLimit is the maximum number of pending channels that we
        // can have. After this point, pending channel opens will start to be
        // rejected.
        pendingChansLimit = 50
)

var (
        // ErrFundingManagerShuttingDown is an error returned when attempting to
        // process a funding request/message but the funding manager has already
        // been signaled to shut down.
        ErrFundingManagerShuttingDown = errors.New("funding manager shutting " +
                "down")

        // ErrConfirmationTimeout is an error returned when we as a responder
        // are waiting for a funding transaction to confirm, but too many
        // blocks pass without confirmation.
        ErrConfirmationTimeout = errors.New("timeout waiting for funding " +
                "confirmation")

        // errUpfrontShutdownScriptNotSupported is returned if an upfront
        // shutdown script is set for a peer that does not support the feature
        // bit.
        errUpfrontShutdownScriptNotSupported = errors.New("peer does not " +
                "support option upfront shutdown script")

        zeroID [32]byte
)

// reservationWithCtx encapsulates a pending channel reservation. This wrapper
// struct is used internally within the funding manager to track and progress
// the funding workflow initiated by incoming/outgoing methods from the target
// peer. Additionally, this struct houses a response and error channel which is
// used to respond to the caller in the case a channel workflow is initiated
// via a local signal such as RPC.
//
// TODO(roasbeef): actually use the context package
//   - deadlines, etc.
type reservationWithCtx struct {
        reservation *lnwallet.ChannelReservation
        peer        lnpeer.Peer

        chanAmt btcutil.Amount

        // forwardingPolicy is the policy provided by the initFundingMsg.
        forwardingPolicy models.ForwardingPolicy

        // Constraints we require for the remote.
        remoteCsvDelay    uint16
        remoteMinHtlc     lnwire.MilliSatoshi
        remoteMaxValue    lnwire.MilliSatoshi
        remoteMaxHtlcs    uint16
        remoteChanReserve btcutil.Amount

        // maxLocalCsv is the maximum csv we will accept from the remote.
        maxLocalCsv uint16

        // channelType is the explicit channel type proposed by the initiator of
        // the channel.
        channelType *lnwire.ChannelType

        updateMtx   sync.RWMutex
        lastUpdated time.Time

        updates chan *lnrpc.OpenStatusUpdate
        err     chan error
}

// isLocked checks the reservation's timestamp to determine whether it is
// locked.
func (r *reservationWithCtx) isLocked() bool {
        r.updateMtx.RLock()
        defer r.updateMtx.RUnlock()

        // The time zero value represents a locked reservation.
        return r.lastUpdated.IsZero()
}

// updateTimestamp updates the reservation's timestamp with the current time.
func (r *reservationWithCtx) updateTimestamp() {
        r.updateMtx.Lock()
        defer r.updateMtx.Unlock()

        r.lastUpdated = time.Now()
}

// InitFundingMsg is sent by an outside subsystem to the funding manager in
// order to kick off a funding workflow with a specified target peer. The
// original request which defines the parameters of the funding workflow are
// embedded within this message giving the funding manager full context w.r.t
// the workflow.
type InitFundingMsg struct {
        // Peer is the peer that we want to open a channel to.
        Peer lnpeer.Peer

        // TargetPubkey is the public key of the peer.
        TargetPubkey *btcec.PublicKey

        // ChainHash is the target genesis hash for this channel.
        ChainHash chainhash.Hash

        // SubtractFees set to true means that fees will be subtracted
        // from the LocalFundingAmt.
        SubtractFees bool

        // LocalFundingAmt is the size of the channel.
        LocalFundingAmt btcutil.Amount

        // BaseFee is the base fee charged for routing payments regardless of
        // the number of milli-satoshis sent.
        BaseFee *uint64

        // FeeRate is the fee rate in ppm (parts per million) that will be
        // charged proportionally based on the value of each forwarded HTLC, the
        // lowest possible rate is 0 with a granularity of 0.000001
        // (millionths).
        FeeRate *uint64

        // PushAmt is the amount pushed to the counterparty.
        PushAmt lnwire.MilliSatoshi

        // FundingFeePerKw is the fee for the funding transaction.
        FundingFeePerKw chainfee.SatPerKWeight

        // Private determines whether or not this channel will be private.
        Private bool

        // MinHtlcIn is the minimum incoming HTLC that we accept.
        MinHtlcIn lnwire.MilliSatoshi

        // RemoteCsvDelay is the CSV delay we require for the remote peer.
        RemoteCsvDelay uint16

        // RemoteChanReserve is the channel reserve we required for the remote
        // peer.
        RemoteChanReserve btcutil.Amount

        // MinConfs indicates the minimum number of confirmations that each
        // output selected to fund the channel should satisfy.
        MinConfs int32

        // ShutdownScript is an optional upfront shutdown script for the
        // channel. This value is optional, so may be nil.
        ShutdownScript lnwire.DeliveryAddress

        // MaxValueInFlight is the maximum amount of coins in MilliSatoshi
        // that can be pending within the channel. It only applies to the
        // remote party.
        MaxValueInFlight lnwire.MilliSatoshi

        // MaxHtlcs is the maximum number of HTLCs that the remote peer
        // can offer us.
        MaxHtlcs uint16

        // MaxLocalCsv is the maximum local csv delay we will accept from our
        // peer.
        MaxLocalCsv uint16

        // FundUpToMaxAmt is the maximum amount to try to commit to. If set, the
        // MinFundAmt field denotes the acceptable minimum amount to commit to,
        // while trying to commit as many coins as possible up to this value.
        FundUpToMaxAmt btcutil.Amount

        // MinFundAmt must be set iff FundUpToMaxAmt is set. It denotes the
        // minimum amount to commit to.
        MinFundAmt btcutil.Amount

        // Outpoints is a list of client-selected outpoints that should be used
        // for funding a channel. If LocalFundingAmt is specified then this
        // amount is allocated from the sum of outpoints towards funding. If
        // the FundUpToMaxAmt is specified the entirety of selected funds is
        // allocated towards channel funding.
        Outpoints []wire.OutPoint

        // ChanFunder is an optional channel funder that allows the caller to
        // control exactly how the channel funding is carried out. If not
        // specified, then the default chanfunding.WalletAssembler will be
        // used.
        ChanFunder chanfunding.Assembler

        // PendingChanID is not all zeroes (the default value), then this will
        // be the pending channel ID used for the funding flow within the wire
        // protocol.
        PendingChanID PendingChanID

        // ChannelType allows the caller to use an explicit channel type for the
        // funding negotiation. This type will only be observed if BOTH sides
        // support explicit channel type negotiation.
        ChannelType *lnwire.ChannelType

        // Memo is any arbitrary information we wish to store locally about the
        // channel that will be useful to our future selves.
        Memo []byte

        // Updates is a channel which updates to the opening status of the
        // channel are sent on.
        Updates chan *lnrpc.OpenStatusUpdate

        // Err is a channel which errors encountered during the funding flow are
        // sent on.
        Err chan error
}

// fundingMsg is sent by the ProcessFundingMsg function and packages a
// funding-specific lnwire.Message along with the lnpeer.Peer that sent it.
type fundingMsg struct {
        msg  lnwire.Message
        peer lnpeer.Peer
}

// pendingChannels is a map instantiated per-peer which tracks all active
// pending single funded channels indexed by their pending channel identifier,
// which is a set of 32-bytes generated via a CSPRNG.
type pendingChannels map[PendingChanID]*reservationWithCtx

// serializedPubKey is used within the FundingManager's activeReservations list
// to identify the nodes with which the FundingManager is actively working to
// initiate new channels.
type serializedPubKey [33]byte

// newSerializedKey creates a new serialized public key from an instance of a
// live pubkey object.
func newSerializedKey(pubKey *btcec.PublicKey) serializedPubKey {
        var s serializedPubKey
        copy(s[:], pubKey.SerializeCompressed())
        return s
}

// DevConfig specifies configs used for integration test only.
type DevConfig struct {
        // ProcessChannelReadyWait is the duration to sleep before processing
        // remote node's channel ready message once the channel as been marked
        // as `channelReadySent`.
        ProcessChannelReadyWait time.Duration

        // MaxWaitNumBlocksFundingConf is the maximum number of blocks to wait
        // for the funding transaction to be confirmed before forgetting
        // channels that aren't initiated by us.
        MaxWaitNumBlocksFundingConf uint32
}

// Config defines the configuration for the FundingManager. All elements
// within the configuration MUST be non-nil for the FundingManager to carry out
// its duties.
type Config struct {
        // Dev specifies config values used in integration test. For
        // production, this config will always be an empty struct.
        Dev *DevConfig

        // NoWumboChans indicates if we're to reject all incoming wumbo channel
        // requests, and also reject all outgoing wumbo channel requests.
        NoWumboChans bool

        // IDKey is the PublicKey that is used to identify this node within the
        // Lightning Network.
        IDKey *btcec.PublicKey

        // IDKeyLoc is the locator for the key that is used to identify this
        // node within the LightningNetwork.
        IDKeyLoc keychain.KeyLocator

        // Wallet handles the parts of the funding process that involves moving
        // funds from on-chain transaction outputs into Lightning channels.
        Wallet *lnwallet.LightningWallet

        // PublishTransaction facilitates the process of broadcasting a
        // transaction to the network.
        PublishTransaction func(*wire.MsgTx, string) error

        // UpdateLabel updates the label that a transaction has in our wallet,
        // overwriting any existing labels.
        UpdateLabel func(chainhash.Hash, string) error

        // FeeEstimator calculates appropriate fee rates based on historical
        // transaction information.
        FeeEstimator chainfee.Estimator

        // Notifier is used by the FundingManager to determine when the
        // channel's funding transaction has been confirmed on the blockchain
        // so that the channel creation process can be completed.
        Notifier chainntnfs.ChainNotifier

        // ChannelDB is the database that keeps track of all channel state.
        ChannelDB *channeldb.ChannelStateDB

        // SignMessage signs an arbitrary message with a given public key. The
        // actual digest signed is the double sha-256 of the message. In the
        // case that the private key corresponding to the passed public key
        // cannot be located, then an error is returned.
        //
        // TODO(roasbeef): should instead pass on this responsibility to a
        // distinct sub-system?
        SignMessage func(keyLoc keychain.KeyLocator,
                msg []byte, doubleHash bool) (*ecdsa.Signature, error)

        // CurrentNodeAnnouncement should return the latest, fully signed node
        // announcement from the backing Lightning Network node with a fresh
        // timestamp.
        CurrentNodeAnnouncement func() (lnwire.NodeAnnouncement, error)

        // SendAnnouncement is used by the FundingManager to send announcement
        // messages to the Gossiper to possibly broadcast to the greater
        // network. A set of optional message fields can be provided to populate
        // any information within the graph that is not included in the gossip
        // message.
        SendAnnouncement func(msg lnwire.Message,
                optionalFields ...discovery.OptionalMsgField) chan error

        // NotifyWhenOnline allows the FundingManager to register with a
        // subsystem that will notify it when the peer comes online. This is
        // used when sending the channelReady message, since it MUST be
        // delivered after the funding transaction is confirmed.
        //
        // NOTE: The peerChan channel must be buffered.
        NotifyWhenOnline func(peer [33]byte, peerChan chan<- lnpeer.Peer)

        // FindChannel queries the database for the channel with the given
        // channel ID. Providing the node's public key is an optimization that
        // prevents deserializing and scanning through all possible channels.
        FindChannel func(node *btcec.PublicKey,
                chanID lnwire.ChannelID) (*channeldb.OpenChannel, error)

        // TempChanIDSeed is a cryptographically random string of bytes that's
        // used as a seed to generate pending channel ID's.
        TempChanIDSeed [32]byte

        // DefaultRoutingPolicy is the default routing policy used when
        // initially announcing channels.
        DefaultRoutingPolicy models.ForwardingPolicy

        // DefaultMinHtlcIn is the default minimum incoming htlc value that is
        // set as a channel parameter.
        DefaultMinHtlcIn lnwire.MilliSatoshi

        // NumRequiredConfs is a function closure that helps the funding
        // manager decide how many confirmations it should require for a
        // channel extended to it. The function is able to take into account
        // the amount of the channel, and any funds we'll be pushed in the
        // process to determine how many confirmations we'll require.
        NumRequiredConfs func(btcutil.Amount, lnwire.MilliSatoshi) uint16

        // RequiredRemoteDelay is a function that maps the total amount in a
        // proposed channel to the CSV delay that we'll require for the remote
        // party. Naturally a larger channel should require a higher CSV delay
        // in order to give us more time to claim funds in the case of a
        // contract breach.
        RequiredRemoteDelay func(btcutil.Amount) uint16

        // RequiredRemoteChanReserve is a function closure that, given the
        // channel capacity and dust limit, will return an appropriate amount
        // for the remote peer's required channel reserve that is to be adhered
        // to at all times.
        RequiredRemoteChanReserve func(capacity,
                dustLimit btcutil.Amount) btcutil.Amount

        // RequiredRemoteMaxValue is a function closure that, given the channel
        // capacity, returns the amount of MilliSatoshis that our remote peer
        // can have in total outstanding HTLCs with us.
        RequiredRemoteMaxValue func(btcutil.Amount) lnwire.MilliSatoshi

        // RequiredRemoteMaxHTLCs is a function closure that, given the channel
        // capacity, returns the number of maximum HTLCs the remote peer can
        // offer us.
        RequiredRemoteMaxHTLCs func(btcutil.Amount) uint16

        // WatchNewChannel is to be called once a new channel enters the final
        // funding stage: waiting for on-chain confirmation. This method sends
        // the channel to the ChainArbitrator so it can watch for any on-chain
        // events related to the channel. We also provide the public key of the
        // node we're establishing a channel with for reconnection purposes.
        WatchNewChannel func(*channeldb.OpenChannel, *btcec.PublicKey) error

        // ReportShortChanID allows the funding manager to report the confirmed
        // short channel ID of a formerly pending zero-conf channel to outside
        // sub-systems.
        ReportShortChanID func(wire.OutPoint) error

        // ZombieSweeperInterval is the periodic time interval in which the
        // zombie sweeper is run.
        ZombieSweeperInterval time.Duration

        // ReservationTimeout is the length of idle time that must pass before
        // a reservation is considered a zombie.
        ReservationTimeout time.Duration

        // MinChanSize is the smallest channel size that we'll accept as an
        // inbound channel. We have such a parameter, as otherwise, nodes could
        // flood us with very small channels that would never really be usable
        // due to fees.
        MinChanSize btcutil.Amount

        // MaxChanSize is the largest channel size that we'll accept as an
        // inbound channel. We have such a parameter, so that you may decide how
        // WUMBO you would like your channel.
        MaxChanSize btcutil.Amount

        // MaxPendingChannels is the maximum number of pending channels we
        // allow for each peer.
        MaxPendingChannels int

        // RejectPush is set true if the fundingmanager should reject any
        // incoming channels having a non-zero push amount.
        RejectPush bool

        // MaxLocalCSVDelay is the maximum csv delay we will allow for our
        // commit output. Channels that exceed this value will be failed.
        MaxLocalCSVDelay uint16

        // NotifyOpenChannelEvent informs the ChannelNotifier when channels
        // transition from pending open to open.
        NotifyOpenChannelEvent func(wire.OutPoint, *btcec.PublicKey)

        // OpenChannelPredicate is a predicate on the lnwire.OpenChannel message
        // and on the requesting node's public key that returns a bool which
        // tells the funding manager whether or not to accept the channel.
        OpenChannelPredicate chanacceptor.ChannelAcceptor

        // NotifyPendingOpenChannelEvent informs the ChannelNotifier when
        // channels enter a pending state.
        NotifyPendingOpenChannelEvent func(wire.OutPoint,
                *channeldb.OpenChannel, *btcec.PublicKey)

        // NotifyFundingTimeout informs the ChannelNotifier when a pending-open
        // channel times out because the funding transaction hasn't confirmed.
        // This is only called for the fundee and only if the channel is
        // zero-conf.
        NotifyFundingTimeout func(wire.OutPoint, *btcec.PublicKey)

        // EnableUpfrontShutdown specifies whether the upfront shutdown script
        // is enabled.
        EnableUpfrontShutdown bool

        // MaxAnchorsCommitFeeRate is the max commitment fee rate we'll use as
        // the initiator for channels of the anchor type.
        MaxAnchorsCommitFeeRate chainfee.SatPerKWeight

        // DeleteAliasEdge allows the Manager to delete an alias channel edge
        // from the graph. It also returns our local to-be-deleted policy.
        DeleteAliasEdge func(scid lnwire.ShortChannelID) (
                *models.ChannelEdgePolicy, error)

        // AliasManager is an implementation of the aliasHandler interface that
        // abstracts away the handling of many alias functions.
        AliasManager aliasHandler

        // IsSweeperOutpoint queries the sweeper store for successfully
        // published sweeps. This is useful to decide for the internal wallet
        // backed funding flow to not use utxos still being swept by the sweeper
        // subsystem.
        IsSweeperOutpoint func(wire.OutPoint) bool

        // 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]

        // AuxSigner is an optional signer that can be used to sign auxiliary
        // leaves for certain custom channel types.
        AuxSigner fn.Option[lnwallet.AuxSigner]

        // AuxResolver is an optional interface that can be used to modify the
        // way contracts are resolved.
        AuxResolver fn.Option[lnwallet.AuxContractResolver]

        // AuxChannelNegotiator is an optional interface that allows aux channel
        // implementations to inject and process custom records over channel
        // related wire messages.
        AuxChannelNegotiator fn.Option[lnwallet.AuxChannelNegotiator]
}

// Manager acts as an orchestrator/bridge between the wallet's
// 'ChannelReservation' workflow, and the wire protocol's funding initiation
// messages. Any requests to initiate the funding workflow for a channel,
// either kicked-off locally or remotely are handled by the funding manager.
// Once a channel's funding workflow has been completed, any local callers, the
// local peer, and possibly the remote peer are notified of the completion of
// the channel workflow. Additionally, any temporary or permanent access
// controls between the wallet and remote peers are enforced via the funding
// manager.
type Manager struct {
        started sync.Once
        stopped sync.Once

        // cfg is a copy of the configuration struct that the FundingManager
        // was initialized with.
        cfg *Config

        // chanIDKey is a cryptographically random key that's used to generate
        // temporary channel ID's.
        chanIDKey [32]byte

        // chanIDNonce is a nonce that's incremented for each new funding
        // reservation created.
        chanIDNonce atomic.Uint64

        // nonceMtx is a mutex that guards the pendingMusigNonces.
        nonceMtx sync.RWMutex

        // pendingMusigNonces is used to store the musig2 nonce we generate to
        // send funding locked until we receive a funding locked message from
        // the remote party. We'll use this to keep track of the nonce we
        // generated, so we send the local+remote nonces to the peer state
        // machine.
        //
        // NOTE: This map is protected by the nonceMtx above.
        //
        // TODO(roasbeef): replace w/ generic concurrent map
        pendingMusigNonces map[lnwire.ChannelID]*musig2.Nonces

        // activeReservations is a map which houses the state of all pending
        // funding workflows.
        activeReservations map[serializedPubKey]pendingChannels

        // signedReservations is a utility map that maps the permanent channel
        // ID of a funding reservation to its temporary channel ID. This is
        // required as mid funding flow, we switch to referencing the channel
        // by its full channel ID once the commitment transactions have been
        // signed by both parties.
        signedReservations map[lnwire.ChannelID]PendingChanID

        // resMtx guards both of the maps above to ensure that all access is
        // goroutine safe.
        resMtx sync.RWMutex

        // fundingMsgs is a channel that relays fundingMsg structs from
        // external sub-systems using the ProcessFundingMsg call.
        fundingMsgs chan *fundingMsg

        // fundingRequests is a channel used to receive channel initiation
        // requests from a local subsystem within the daemon.
        fundingRequests chan *InitFundingMsg

        localDiscoverySignals *lnutils.SyncMap[lnwire.ChannelID, chan struct{}]

        handleChannelReadyBarriers *lnutils.SyncMap[lnwire.ChannelID, struct{}]

        quit chan struct{}
        wg   sync.WaitGroup
}

// channelOpeningState represents the different states a channel can be in
// between the funding transaction has been confirmed and the channel is
// announced to the network and ready to be used.
type channelOpeningState uint8

const (
        // markedOpen is the opening state of a channel if the funding
        // transaction is confirmed on-chain, but channelReady is not yet
        // successfully sent to the other peer.
        markedOpen channelOpeningState = iota

        // channelReadySent is the opening state of a channel if the
        // channelReady message has successfully been sent to the other peer,
        // but we still haven't announced the channel to the network.
        channelReadySent

        // addedToGraph is the opening state of a channel if the channel has
        // been successfully added to the graph immediately after the
        // channelReady message has been sent, but we still haven't announced
        // the channel to the network.
        addedToGraph
)

func (c channelOpeningState) String() string {
        switch c {
        case markedOpen:
                return "markedOpen"
        case channelReadySent:
                return "channelReadySent"
        case addedToGraph:
                return "addedToGraph"
        default:
                return "unknown"
        }
}

// NewFundingManager creates and initializes a new instance of the
// fundingManager.
func NewFundingManager(cfg Config) (*Manager, error) {
        return &Manager{
                cfg:       &cfg,
                chanIDKey: cfg.TempChanIDSeed,
                activeReservations: make(
                        map[serializedPubKey]pendingChannels,
                ),
                signedReservations: make(
                        map[lnwire.ChannelID][32]byte,
                ),
                fundingMsgs: make(
                        chan *fundingMsg, msgBufferSize,
                ),
                fundingRequests: make(
                        chan *InitFundingMsg, msgBufferSize,
                ),
                localDiscoverySignals: &lnutils.SyncMap[
                        lnwire.ChannelID, chan struct{},
                ]{},
                handleChannelReadyBarriers: &lnutils.SyncMap[
                        lnwire.ChannelID, struct{},
                ]{},
                pendingMusigNonces: make(
                        map[lnwire.ChannelID]*musig2.Nonces,
                ),
                quit: make(chan struct{}),
        }, nil
}

// Start launches all helper goroutines required for handling requests sent
// to the funding manager.
func (f *Manager) Start() error {
        var err error
        f.started.Do(func() {
                log.Info("Funding manager starting")
                err = f.start()
        })
        return err
}

func (f *Manager) start() error {
        // Upon restart, the Funding Manager will check the database to load any
        // channels that were  waiting for their funding transactions to be
        // confirmed on the blockchain at the time when the daemon last went
        // down.
        // TODO(roasbeef): store height that funding finished?
        //  * would then replace call below
        allChannels, err := f.cfg.ChannelDB.FetchAllChannels()
        if err != nil {
                return err
        }

        for _, channel := range allChannels {
                chanID := lnwire.NewChanIDFromOutPoint(channel.FundingOutpoint)

                // For any channels that were in a pending state when the
                // daemon was last connected, the Funding Manager will
                // re-initialize the channel barriers, and republish the
                // funding transaction if we're the initiator.
                if channel.IsPending {
                        log.Tracef("Loading pending ChannelPoint(%v), "+
                                "creating chan barrier",
                                channel.FundingOutpoint)

                        f.localDiscoverySignals.Store(
                                chanID, make(chan struct{}),
                        )

                        // Rebroadcast the funding transaction for any pending
                        // channel that we initiated. No error will be returned
                        // if the transaction already has been broadcast.
                        chanType := channel.ChanType
                        if chanType.IsSingleFunder() &&
                                chanType.HasFundingTx() &&
                                channel.IsInitiator {

                                f.rebroadcastFundingTx(channel)
                        }
                } else if channel.ChanType.IsSingleFunder() &&
                        channel.ChanType.HasFundingTx() &&
                        channel.IsZeroConf() && channel.IsInitiator &&
                        !channel.ZeroConfConfirmed() {

                        // Rebroadcast the funding transaction for unconfirmed
                        // zero-conf channels if we have the funding tx and are
                        // also the initiator.
                        f.rebroadcastFundingTx(channel)
                }

                // We will restart the funding state machine for all channels,
                // which will wait for the channel's funding transaction to be
                // confirmed on the blockchain, and transmit the messages
                // necessary for the channel to be operational.
                f.wg.Add(1)
                go f.advanceFundingState(channel, chanID, nil)
        }

        f.wg.Add(1) // TODO(roasbeef): tune
        go f.reservationCoordinator()

        return nil
}

// Stop signals all helper goroutines to execute a graceful shutdown. This
// method will block until all goroutines have exited.
func (f *Manager) Stop() error {
        f.stopped.Do(func() {
                log.Info("Funding manager shutting down...")
                defer log.Debug("Funding manager shutdown complete")

                close(f.quit)
                f.wg.Wait()
        })

        return nil
}

// rebroadcastFundingTx publishes the funding tx on startup for each
// unconfirmed channel.
func (f *Manager) rebroadcastFundingTx(c *channeldb.OpenChannel) {
        var fundingTxBuf bytes.Buffer
        err := c.FundingTxn.Serialize(&fundingTxBuf)
        if err != nil {
                log.Errorf("Unable to serialize funding transaction %v: %v",
                        c.FundingTxn.TxHash(), err)

                // Clear the buffer of any bytes that were written before the
                // serialization error to prevent logging an incomplete
                // transaction.
                fundingTxBuf.Reset()
        } else {
                log.Debugf("Rebroadcasting funding tx for ChannelPoint(%v): "+
                        "%x", c.FundingOutpoint, fundingTxBuf.Bytes())
        }

        // Set a nil short channel ID at this stage because we do not know it
        // until our funding tx confirms.
        label := labels.MakeLabel(labels.LabelTypeChannelOpen, nil)

        err = f.cfg.PublishTransaction(c.FundingTxn, label)
        if err != nil {
                log.Errorf("Unable to rebroadcast funding tx %x for "+
                        "ChannelPoint(%v): %v", fundingTxBuf.Bytes(),
                        c.FundingOutpoint, err)
        }
}

// PendingChanID is a type that represents a pending channel ID. This might be
// selected by the caller, but if not, will be automatically selected.
type PendingChanID = [32]byte

// nextPendingChanID returns the next free pending channel ID to be used to
// identify a particular future channel funding workflow.
func (f *Manager) nextPendingChanID() PendingChanID {
        // Obtain a fresh nonce. We do this by encoding the incremented nonce.
        nextNonce := f.chanIDNonce.Add(1)

        var nonceBytes [8]byte
        binary.LittleEndian.PutUint64(nonceBytes[:], nextNonce)

        // We'll generate the next pending channelID by "encrypting" 32-bytes
        // of zeroes which'll extract 32 random bytes from our stream cipher.
        var (
                nextChanID PendingChanID
                zeroes     [32]byte
        )
        salsa20.XORKeyStream(
                nextChanID[:], zeroes[:], nonceBytes[:], &f.chanIDKey,
        )

        return nextChanID
}

// CancelPeerReservations cancels all active reservations associated with the
// passed node. This will ensure any outputs which have been pre committed,
// (and thus locked from coin selection), are properly freed.
func (f *Manager) CancelPeerReservations(nodePub [33]byte) {
        log.Debugf("Cancelling all reservations for peer %x", nodePub[:])

        f.resMtx.Lock()
        defer f.resMtx.Unlock()

        // We'll attempt to look up this node in the set of active
        // reservations.  If they don't have any, then there's no further work
        // to be done.
        nodeReservations, ok := f.activeReservations[nodePub]
        if !ok {
                log.Debugf("No active reservations for node: %x", nodePub[:])
                return
        }

        // If they do have any active reservations, then we'll cancel all of
        // them (which releases any locked UTXO's), and also delete it from the
        // reservation map.
        for pendingID, resCtx := range nodeReservations {
                if err := resCtx.reservation.Cancel(); err != nil {
                        log.Errorf("unable to cancel reservation for "+
                                "node=%x: %v", nodePub[:], err)
                }

                resCtx.err <- fmt.Errorf("peer disconnected")
                delete(nodeReservations, pendingID)
        }

        // Finally, we'll delete the node itself from the set of reservations.
        delete(f.activeReservations, nodePub)
}

// chanIdentifier wraps pending channel ID and channel ID into one struct so
// it's easier to identify a specific channel.
//
// TODO(yy): move to a different package to hide the private fields so direct
// access is disabled.
type chanIdentifier struct {
        // tempChanID is the pending channel ID created by the funder when
        // initializing the funding flow. For fundee, it's received from the
        // `open_channel` message.
        tempChanID lnwire.ChannelID

        // chanID is the channel ID created by the funder once the
        // `accept_channel` message is received. For fundee, it's received from
        // the `funding_created` message.
        chanID lnwire.ChannelID

        // chanIDSet is a boolean indicates whether the active channel ID is
        // set for this identifier. For zero conf channels, the `chanID` can be
        // all-zero, which is the same as the empty value of `ChannelID`. To
        // avoid the confusion, we use this boolean to explicitly signal
        // whether the `chanID` is set or not.
        chanIDSet bool
}

// newChanIdentifier creates a new chanIdentifier.
func newChanIdentifier(tempChanID lnwire.ChannelID) *chanIdentifier {
        return &chanIdentifier{
                tempChanID: tempChanID,
        }
}

// setChanID updates the `chanIdentifier` with the active channel ID.
func (c *chanIdentifier) setChanID(chanID lnwire.ChannelID) {
        c.chanID = chanID
        c.chanIDSet = true
}

// hasChanID returns true if the active channel ID has been set.
func (c *chanIdentifier) hasChanID() bool {
        return c.chanIDSet
}

// failFundingFlow will fail the active funding flow with the target peer,
// identified by its unique temporary channel ID. This method will send an
// error to the remote peer, and also remove the reservation from our set of
// pending reservations.
//
// TODO(roasbeef): if peer disconnects, and haven't yet broadcast funding
// transaction, then all reservations should be cleared.
func (f *Manager) failFundingFlow(peer lnpeer.Peer, cid *chanIdentifier,
        fundingErr error) {

        log.Debugf("Failing funding flow for pending_id=%v: %v",
                cid.tempChanID, fundingErr)

        // First, notify Brontide to remove the pending channel.
        //
        // NOTE: depending on where we fail the flow, we may not have the
        // active channel ID yet.
        if cid.hasChanID() {
                err := peer.RemovePendingChannel(cid.chanID)
                if err != nil {
                        log.Errorf("Unable to remove channel %v with peer %x: "+
                                "%v", cid,
                                peer.IdentityKey().SerializeCompressed(), err)
                }
        }

        ctx, err := f.cancelReservationCtx(
                peer.IdentityKey(), cid.tempChanID, false,
        )
        if err != nil {
                log.Errorf("unable to cancel reservation: %v", err)
        }

        // In case the case where the reservation existed, send the funding
        // error on the error channel.
        if ctx != nil {
                ctx.err <- fundingErr
        }

        // We only send the exact error if it is part of out whitelisted set of
        // errors (lnwire.FundingError or lnwallet.ReservationError).
        var msg lnwire.ErrorData
        switch e := fundingErr.(type) {
        // Let the actual error message be sent to the remote for the
        // whitelisted types.
        case lnwallet.ReservationError:
                msg = lnwire.ErrorData(e.Error())
        case lnwire.FundingError:
                msg = lnwire.ErrorData(e.Error())
        case chanacceptor.ChanAcceptError:
                msg = lnwire.ErrorData(e.Error())

        // For all other error types we just send a generic error.
        default:
                msg = lnwire.ErrorData("funding failed due to internal error")
        }

        errMsg := &lnwire.Error{
                ChanID: cid.tempChanID,
                Data:   msg,
        }

        log.Debugf("Sending funding error to peer (%x): %v",
                peer.IdentityKey().SerializeCompressed(),
                lnutils.SpewLogClosure(errMsg))

        if err := peer.SendMessage(false, errMsg); err != nil {
                log.Errorf("unable to send error message to peer %v", err)
        }
}

// sendWarning sends a new warning message to the target peer, targeting the
// specified cid with the passed funding error.
func (f *Manager) sendWarning(peer lnpeer.Peer, cid *chanIdentifier,
        fundingErr error) {

        msg := fundingErr.Error()

        errMsg := &lnwire.Warning{
                ChanID: cid.tempChanID,
                Data:   lnwire.WarningData(msg),
        }

        log.Debugf("Sending funding warning to peer (%x): %v",
                peer.IdentityKey().SerializeCompressed(),
                lnutils.SpewLogClosure(errMsg),
        )

        if err := peer.SendMessage(false, errMsg); err != nil {
                log.Errorf("unable to send error message to peer %v", err)
        }
}

// reservationCoordinator is the primary goroutine tasked with progressing the
// funding workflow between the wallet, and any outside peers or local callers.
//
// NOTE: This MUST be run as a goroutine.
func (f *Manager) reservationCoordinator() {
        defer f.wg.Done()

        zombieSweepTicker := time.NewTicker(f.cfg.ZombieSweeperInterval)
        defer zombieSweepTicker.Stop()

        for {
                select {
                case fmsg := <-f.fundingMsgs:
                        switch msg := fmsg.msg.(type) {
                        case *lnwire.OpenChannel:
                                f.fundeeProcessOpenChannel(fmsg.peer, msg)

                        case *lnwire.AcceptChannel:
                                f.funderProcessAcceptChannel(fmsg.peer, msg)

                        case *lnwire.FundingCreated:
                                f.fundeeProcessFundingCreated(fmsg.peer, msg)

                        case *lnwire.FundingSigned:
                                f.funderProcessFundingSigned(fmsg.peer, msg)

                        case *lnwire.ChannelReady:
                                f.wg.Add(1)
                                go f.handleChannelReady(fmsg.peer, msg)

                        case *lnwire.Warning:
                                f.handleWarningMsg(fmsg.peer, msg)

                        case *lnwire.Error:
                                f.handleErrorMsg(fmsg.peer, msg)
                        }
                case req := <-f.fundingRequests:
                        f.handleInitFundingMsg(req)

                case <-zombieSweepTicker.C:
                        f.pruneZombieReservations()

                case <-f.quit:
                        return
                }
        }
}

// advanceFundingState will advance the channel through the steps after the
// funding transaction is broadcasted, up until the point where the channel is
// ready for operation. This includes waiting for the funding transaction to
// confirm, sending channel_ready to the peer, adding the channel to the graph,
// and announcing the channel. The updateChan can be set non-nil to get
// OpenStatusUpdates.
//
// NOTE: This MUST be run as a goroutine.
func (f *Manager) advanceFundingState(channel *channeldb.OpenChannel,
        pendingChanID PendingChanID,
        updateChan chan<- *lnrpc.OpenStatusUpdate) {

        defer f.wg.Done()

        // If the channel is still pending we must wait for the funding
        // transaction to confirm.
        if channel.IsPending {
                err := f.advancePendingChannelState(channel, pendingChanID)
                if err != nil {
                        log.Errorf("Unable to advance pending state of "+
                                "ChannelPoint(%v): %v",
                                channel.FundingOutpoint, err)
                        return
                }
        }

        var chanOpts []lnwallet.ChannelOpt
        f.cfg.AuxLeafStore.WhenSome(func(s lnwallet.AuxLeafStore) {
                chanOpts = append(chanOpts, lnwallet.WithLeafStore(s))
        })
        f.cfg.AuxSigner.WhenSome(func(s lnwallet.AuxSigner) {
                chanOpts = append(chanOpts, lnwallet.WithAuxSigner(s))
        })
        f.cfg.AuxResolver.WhenSome(func(s lnwallet.AuxContractResolver) {
                chanOpts = append(chanOpts, lnwallet.WithAuxResolver(s))
        })

        // We create the state-machine object which wraps the database state.
        lnChannel, err := lnwallet.NewLightningChannel(
                nil, channel, nil, chanOpts...,
        )
        if err != nil {
                log.Errorf("Unable to create LightningChannel(%v): %v",
                        channel.FundingOutpoint, err)
                return
        }

        for {
                channelState, shortChanID, err := f.getChannelOpeningState(
                        &channel.FundingOutpoint,
                )
                if err == channeldb.ErrChannelNotFound {
                        // Channel not in fundingManager's opening database,
                        // meaning it was successfully announced to the
                        // network.
                        // TODO(halseth): could do graph consistency check
                        // here, and re-add the edge if missing.
                        log.Debugf("ChannelPoint(%v) with chan_id=%x not "+
                                "found in opening database, assuming already "+
                                "announced to the network",
                                channel.FundingOutpoint, pendingChanID)
                        return
                } else if err != nil {
                        log.Errorf("Unable to query database for "+
                                "channel opening state(%v): %v",
                                channel.FundingOutpoint, err)
                        return
                }

                // If we did find the channel in the opening state database, we
                // have seen the funding transaction being confirmed, but there
                // are still steps left of the setup procedure. We continue the
                // procedure where we left off.
                err = f.stateStep(
                        channel, lnChannel, shortChanID, pendingChanID,
                        channelState, updateChan,
                )
                if err != nil {
                        log.Errorf("Unable to advance state(%v): %v",
                                channel.FundingOutpoint, err)
                        return
                }
        }
}

// stateStep advances the confirmed channel one step in the funding state
// machine. This method is synchronous and the new channel opening state will
// have been written to the database when it successfully returns. The
// updateChan can be set non-nil to get OpenStatusUpdates.
func (f *Manager) stateStep(channel *channeldb.OpenChannel,
        lnChannel *lnwallet.LightningChannel,
        shortChanID *lnwire.ShortChannelID, pendingChanID PendingChanID,
        channelState channelOpeningState,
        updateChan chan<- *lnrpc.OpenStatusUpdate) error {

        chanID := lnwire.NewChanIDFromOutPoint(channel.FundingOutpoint)
        log.Debugf("Channel(%v) with ShortChanID %v has opening state %v",
                chanID, shortChanID, channelState)

        switch channelState {
        // The funding transaction was confirmed, but we did not successfully
        // send the channelReady message to the peer, so let's do that now.
        case markedOpen:
                err := f.sendChannelReady(channel, lnChannel)
                if err != nil {
                        return fmt.Errorf("failed sending channelReady: %w",
                                err)
                }

                // As the channelReady message is now sent to the peer, the
                // channel is moved to the next state of the state machine. It
                // will be moved to the last state (actually deleted from the
                // database) after the channel is finally announced.
                err = f.saveChannelOpeningState(
                        &channel.FundingOutpoint, channelReadySent,
                        shortChanID,
                )
                if err != nil {
                        return fmt.Errorf("error setting channel state to"+
                                " channelReadySent: %w", err)
                }

                log.Debugf("Channel(%v) with ShortChanID %v: successfully "+
                        "sent ChannelReady", chanID, shortChanID)

                return nil

        // channelReady was sent to peer, but the channel was not added to the
        // graph and the channel announcement was not sent.
        case channelReadySent:
                // We must wait until we've received the peer's channel_ready
                // before sending a channel_update according to BOLT#07.
                received, err := f.receivedChannelReady(
                        channel.IdentityPub, chanID,
                )
                if err != nil {
                        return fmt.Errorf("failed to check if channel_ready "+
                                "was received: %v", err)
                }

                if !received {
                        // We haven't received ChannelReady, so we'll continue
                        // to the next iteration of the loop after sleeping for
                        // checkPeerChannelReadyInterval.
                        select {
                        case <-time.After(checkPeerChannelReadyInterval):
                        case <-f.quit:
                                return ErrFundingManagerShuttingDown
                        }

                        return nil
                }

                return f.handleChannelReadyReceived(
                        channel, shortChanID, pendingChanID, updateChan,
                )

        // The channel was added to the Router's topology, but the channel
        // announcement was not sent.
        case addedToGraph:
                if channel.IsZeroConf() {
                        // If this is a zero-conf channel, then we will wait
                        // for it to be confirmed before announcing it to the
                        // greater network.
                        err := f.waitForZeroConfChannel(channel)
                        if err != nil {
                                return fmt.Errorf("failed waiting for zero "+
                                        "channel: %v", err)
                        }

                        // Update the local shortChanID variable such that
                        // annAfterSixConfs uses the confirmed SCID.
                        confirmedScid := channel.ZeroConfRealScid()
                        shortChanID = &confirmedScid
                }

                err := f.annAfterSixConfs(channel, shortChanID)
                if err != nil {
                        return fmt.Errorf("error sending channel "+
                                "announcement: %v", err)
                }

                // We delete the channel opening state from our internal
                // database as the opening process has succeeded. We can do
                // this because we assume the AuthenticatedGossiper queues the
                // announcement messages, and persists them in case of a daemon
                // shutdown.
                err = f.deleteChannelOpeningState(&channel.FundingOutpoint)
                if err != nil {
                        return fmt.Errorf("error deleting channel state: %w",
                                err)
                }

                // After the fee parameters have been stored in the
                // announcement we can delete them from the database. For
                // private channels we do not announce the channel policy to
                // the network but still need to delete them from the database.
                err = f.deleteInitialForwardingPolicy(chanID)
                if err != nil {
                        log.Infof("Could not delete initial policy for chanId "+
                                "%x", chanID)
                }

                log.Debugf("Channel(%v) with ShortChanID %v: successfully "+
                        "announced", chanID, shortChanID)

                return nil
        }

        return fmt.Errorf("undefined channelState: %v", channelState)
}

// advancePendingChannelState waits for a pending channel's funding tx to
// confirm, and marks it open in the database when that happens.
func (f *Manager) advancePendingChannelState(channel *channeldb.OpenChannel,
        pendingChanID PendingChanID) error {

        if channel.IsZeroConf() {
                // Persist the alias to the alias database.
                baseScid := channel.ShortChannelID
                err := f.cfg.AliasManager.AddLocalAlias(
                        baseScid, baseScid, true, false,
                )
                if err != nil {
                        return fmt.Errorf("error adding local alias to "+
                                "store: %v", err)
                }

                // We don't wait for zero-conf channels to be confirmed and
                // instead immediately proceed with the rest of the funding
                // flow. The channel opening state is stored under the alias
                // SCID.
                err = f.saveChannelOpeningState(
                        &channel.FundingOutpoint, markedOpen,
                        &channel.ShortChannelID,
                )
                if err != nil {
                        return fmt.Errorf("error setting zero-conf channel "+
                                "state to markedOpen: %v", err)
                }

                // The ShortChannelID is already set since it's an alias, but
                // we still need to mark the channel as no longer pending.
                err = channel.MarkAsOpen(channel.ShortChannelID)
                if err != nil {
                        return fmt.Errorf("error setting zero-conf channel's "+
                                "pending flag to false: %v", err)
                }

                // Inform the ChannelNotifier that the channel has transitioned
                // from pending open to open.
                f.cfg.NotifyOpenChannelEvent(
                        channel.FundingOutpoint, channel.IdentityPub,
                )

                // Find and close the discoverySignal for this channel such
                // that ChannelReady messages will be processed.
                chanID := lnwire.NewChanIDFromOutPoint(channel.FundingOutpoint)
                discoverySignal, ok := f.localDiscoverySignals.Load(chanID)
                if ok {
                        close(discoverySignal)
                }

                return nil
        }

        confChannel, err := f.waitForFundingWithTimeout(channel)
        if err == ErrConfirmationTimeout {
                return f.fundingTimeout(channel, pendingChanID)
        } else if err != nil {
                return fmt.Errorf("error waiting for funding "+
                        "confirmation for ChannelPoint(%v): %v",
                        channel.FundingOutpoint, err)
        }

        if blockchain.IsCoinBaseTx(confChannel.fundingTx) {
                // If it's a coinbase transaction, we need to wait for it to
                // mature. We wait out an additional MinAcceptDepth on top of
                // the coinbase maturity as an extra margin of safety.
                maturity := f.cfg.Wallet.Cfg.NetParams.CoinbaseMaturity
                numCoinbaseConfs := uint32(maturity)

                if channel.NumConfsRequired > maturity {
                        numCoinbaseConfs = uint32(channel.NumConfsRequired)
                }

                txid := &channel.FundingOutpoint.Hash
                fundingScript, err := makeFundingScript(channel)
                if err != nil {
                        log.Errorf("unable to create funding script for "+
                                "ChannelPoint(%v): %v",
                                channel.FundingOutpoint, err)

                        return err
                }

                confNtfn, err := f.cfg.Notifier.RegisterConfirmationsNtfn(
                        txid, fundingScript, numCoinbaseConfs,
                        channel.BroadcastHeight(),
                )
                if err != nil {
                        log.Errorf("Unable to register for confirmation of "+
                                "ChannelPoint(%v): %v",
                                channel.FundingOutpoint, err)

                        return err
                }

                select {
                case _, ok := <-confNtfn.Confirmed:
                        if !ok {
                                return fmt.Errorf("ChainNotifier shutting "+
                                        "down, can't complete funding flow "+
                                        "for ChannelPoint(%v)",
                                        channel.FundingOutpoint)
                        }

                case <-f.quit:
                        return ErrFundingManagerShuttingDown
                }
        }

        // Success, funding transaction was confirmed.
        chanID := lnwire.NewChanIDFromOutPoint(channel.FundingOutpoint)
        log.Debugf("ChannelID(%v) is now fully confirmed! "+
                "(shortChanID=%v)", chanID, confChannel.shortChanID)

        err = f.handleFundingConfirmation(channel, confChannel)
        if err != nil {
                return fmt.Errorf("unable to handle funding "+
                        "confirmation for ChannelPoint(%v): %v",
                        channel.FundingOutpoint, err)
        }

        return nil
}

// ProcessFundingMsg sends a message to the internal fundingManager goroutine,
// allowing it to handle the lnwire.Message.
func (f *Manager) ProcessFundingMsg(msg lnwire.Message, peer lnpeer.Peer) {
        select {
        case f.fundingMsgs <- &fundingMsg{msg, peer}:
        case <-f.quit:
                return
        }
}

// fundeeProcessOpenChannel creates an initial 'ChannelReservation' within the
// wallet, then responds to the source peer with an accept channel message
// progressing the funding workflow.
//
// TODO(roasbeef): add error chan to all, let channelManager handle
// error+propagate.
//
//nolint:funlen
func (f *Manager) fundeeProcessOpenChannel(peer lnpeer.Peer,
        msg *lnwire.OpenChannel) {

        // Check number of pending channels to be smaller than maximum allowed
        // number and send ErrorGeneric to remote peer if condition is
        // violated.
        peerPubKey := peer.IdentityKey()
        peerIDKey := newSerializedKey(peerPubKey)

        amt := msg.FundingAmount

        // We get all pending channels for this peer. This is the list of the
        // active reservations and the channels pending open in the database.
        f.resMtx.RLock()
        reservations := f.activeReservations[peerIDKey]

        // We don't count reservations that were created from a canned funding
        // shim. The user has registered the shim and therefore expects this
        // channel to arrive.
        numPending := 0
        for _, res := range reservations {
                if !res.reservation.IsCannedShim() {
                        numPending++
                }
        }
        f.resMtx.RUnlock()

        // Create the channel identifier.
        cid := newChanIdentifier(msg.PendingChannelID)

        // Also count the channels that are already pending. There we don't know
        // the underlying intent anymore, unfortunately.
        channels, err := f.cfg.ChannelDB.FetchOpenChannels(peerPubKey)
        if err != nil {
                f.failFundingFlow(peer, cid, err)
                return
        }

        for _, c := range channels {
                // Pending channels that have a non-zero thaw height were also
                // created through a canned funding shim. Those also don't
                // count towards the DoS protection limit.
                //
                // TODO(guggero): Properly store the funding type (wallet, shim,
                // PSBT) on the channel so we don't need to use the thaw height.
                if c.IsPending && c.ThawHeight == 0 {
                        numPending++
                }
        }

        // TODO(roasbeef): modify to only accept a _single_ pending channel per
        // block unless white listed
        if numPending >= f.cfg.MaxPendingChannels {
                f.failFundingFlow(peer, cid, lnwire.ErrMaxPendingChannels)

                return
        }

        // Ensure that the pendingChansLimit is respected.
        pendingChans, err := f.cfg.ChannelDB.FetchPendingChannels()
        if err != nil {
                f.failFundingFlow(peer, cid, err)
                return
        }

        if len(pendingChans) > pendingChansLimit {
                f.failFundingFlow(peer, cid, lnwire.ErrMaxPendingChannels)
                return
        }

        // We'll also reject any requests to create channels until we're fully
        // synced to the network as we won't be able to properly validate the
        // confirmation of the funding transaction.
        isSynced, _, err := f.cfg.Wallet.IsSynced()
        if err != nil || !isSynced {
                if err != nil {
                        log.Errorf("unable to query wallet: %v", err)
                }
                err := errors.New("Synchronizing blockchain")
                f.failFundingFlow(peer, cid, err)
                return
        }

        // Ensure that the remote party respects our maximum channel size.
        if amt > f.cfg.MaxChanSize {
                f.failFundingFlow(
                        peer, cid,
                        lnwallet.ErrChanTooLarge(amt, f.cfg.MaxChanSize),
                )
                return
        }

        // We'll, also ensure that the remote party isn't attempting to propose
        // a channel that's below our current min channel size.
        if amt < f.cfg.MinChanSize {
                f.failFundingFlow(
                        peer, cid,
                        lnwallet.ErrChanTooSmall(amt, f.cfg.MinChanSize),
                )
                return
        }

        // If request specifies non-zero push amount and 'rejectpush' is set,
        // signal an error.
        if f.cfg.RejectPush && msg.PushAmount > 0 {
                f.failFundingFlow(peer, cid, lnwallet.ErrNonZeroPushAmount())
                return
        }

        // Send the OpenChannel request to the ChannelAcceptor to determine
        // whether this node will accept the channel.
        chanReq := &chanacceptor.ChannelAcceptRequest{
                Node:        peer.IdentityKey(),
                OpenChanMsg: msg,
        }

        // Query our channel acceptor to determine whether we should reject
        // the channel.
        acceptorResp := f.cfg.OpenChannelPredicate.Accept(chanReq)
        if acceptorResp.RejectChannel() {
                f.failFundingFlow(peer, cid, acceptorResp.ChanAcceptError)
                return
        }

        log.Infof("Recv'd fundingRequest(amt=%v, push=%v, delay=%v, "+
                "pendingId=%x) from peer(%x)", amt, msg.PushAmount,
                msg.CsvDelay, msg.PendingChannelID,
                peer.IdentityKey().SerializeCompressed())

        // Attempt to initialize a reservation within the wallet. If the wallet
        // has insufficient resources to create the channel, then the
        // reservation attempt may be rejected. Note that since we're on the
        // responding side of a single funder workflow, we don't commit any
        // funds to the channel ourselves.
        //
        // Before we init the channel, we'll also check to see what commitment
        // format we can use with this peer. This is dependent on *both* us and
        // the remote peer are signaling the proper feature bit if we're using
        // implicit negotiation, and simply the channel type sent over if we're
        // using explicit negotiation.
        chanType, commitType, err := negotiateCommitmentType(
                msg.ChannelType, peer.LocalFeatures(), peer.RemoteFeatures(),
        )
        if err != nil {
                // TODO(roasbeef): should be using soft errors
                log.Errorf("channel type negotiation failed: %v", err)
                f.failFundingFlow(peer, cid, err)
                return
        }

        var scidFeatureVal bool
        if hasFeatures(
                peer.LocalFeatures(), peer.RemoteFeatures(),
                lnwire.ScidAliasOptional,
        ) {

                scidFeatureVal = true
        }

        var (
                zeroConf bool
                scid     bool
        )

        // Only echo back a channel type in AcceptChannel if we actually used
        // explicit negotiation above.
        if chanType != nil {
                // Check if the channel type includes the zero-conf or
                // scid-alias bits.
                featureVec := lnwire.RawFeatureVector(*chanType)
                zeroConf = featureVec.IsSet(lnwire.ZeroConfRequired)
                scid = featureVec.IsSet(lnwire.ScidAliasRequired)

                // If the zero-conf channel type was negotiated, ensure that
                // the acceptor allows it.
                if zeroConf && !acceptorResp.ZeroConf {
                        // Fail the funding flow.
                        flowErr := fmt.Errorf("channel acceptor blocked " +
                                "zero-conf channel negotiation")
                        log.Errorf("Cancelling funding flow for %v based on "+
                                "channel acceptor response: %v", cid, flowErr)
                        f.failFundingFlow(peer, cid, flowErr)
                        return
                }

                // If the zero-conf channel type wasn't negotiated and the
                // fundee still wants a zero-conf channel, perform more checks.
                // Require that both sides have the scid-alias feature bit set.
                // We don't require anchors here - this is for compatibility
                // with LDK.
                if !zeroConf && acceptorResp.ZeroConf {
                        if !scidFeatureVal {
                                // Fail the funding flow.
                                flowErr := fmt.Errorf("scid-alias feature " +
                                        "must be negotiated for zero-conf")
                                log.Errorf("Cancelling funding flow for "+
                                        "zero-conf channel %v: %v", cid,
                                        flowErr)
                                f.failFundingFlow(peer, cid, flowErr)
                                return
                        }

                        // Set zeroConf to true to enable the zero-conf flow.
                        zeroConf = true
                }
        }

        public := msg.ChannelFlags&lnwire.FFAnnounceChannel != 0
        switch {
        // Sending the option-scid-alias channel type for a public channel is
        // disallowed.
        case public && scid:
                err = fmt.Errorf("option-scid-alias chantype for public " +
                        "channel")
                log.Errorf("Cancelling funding flow for public channel %v "+
                        "with scid-alias: %v", cid, err)
                f.failFundingFlow(peer, cid, err)

                return

        // The current variant of taproot channels can only be used with
        // unadvertised channels for now.
        case commitType.IsTaproot() && public:
                err = fmt.Errorf("taproot channel type for public channel")
                log.Errorf("Cancelling funding flow for public taproot "+
                        "channel %v: %v", cid, err)
                f.failFundingFlow(peer, cid, err)

                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 := fn.MapOptionZ(
                f.cfg.AuxFundingController,
                func(c AuxFundingController) AuxTapscriptResult {
                        return c.DeriveTapscriptRoot(msg.PendingChannelID)
                },
        ).Unpack()
        if err != nil {
                err = fmt.Errorf("error deriving tapscript root: %w", err)
                log.Error(err)
                f.failFundingFlow(peer, cid, err)

                return
        }

        req := &lnwallet.InitFundingReserveMsg{
                ChainHash:        &msg.ChainHash,
                PendingChanID:    msg.PendingChannelID,
                NodeID:           peer.IdentityKey(),
                NodeAddr:         peer.Address(),
                LocalFundingAmt:  0,
                RemoteFundingAmt: amt,
                CommitFeePerKw:   chainfee.SatPerKWeight(msg.FeePerKiloWeight),
                FundingFeePerKw:  0,
                PushMSat:         msg.PushAmount,
                Flags:            msg.ChannelFlags,
                MinConfs:         1,
                CommitType:       commitType,
                ZeroConf:         zeroConf,
                OptionScidAlias:  scid,
                ScidAliasFeature: scidFeatureVal,
                TapscriptRoot:    tapscriptRoot,
        }

        reservation, err := f.cfg.Wallet.InitChannelReservation(req)
        if err != nil {
                log.Errorf("Unable to initialize reservation: %v", err)
                f.failFundingFlow(peer, cid, err)
                return
        }

        log.Debugf("Initialized channel reservation: zeroConf=%v, psbt=%v, "+
                "cannedShim=%v", reservation.IsZeroConf(),
                reservation.IsPsbt(), reservation.IsCannedShim())

        if zeroConf {
                // Store an alias for zero-conf channels. Other option-scid
                // channels will do this at a later point.
                aliasScid, err := f.cfg.AliasManager.RequestAlias()
                if err != nil {
                        log.Errorf("Unable to request alias: %v", err)
                        f.failFundingFlow(peer, cid, err)
                        return
                }

                reservation.AddAlias(aliasScid)
        }

        // As we're the responder, we get to specify the number of confirmations
        // that we require before both of us consider the channel open. We'll
        // use our mapping to derive the proper number of confirmations based on
        // the amount of the channel, and also if any funds are being pushed to
        // us. If a depth value was set by our channel acceptor, we will use
        // that value instead.
        numConfsReq := f.cfg.NumRequiredConfs(msg.FundingAmount, msg.PushAmount)
        if acceptorResp.MinAcceptDepth != 0 {
                numConfsReq = acceptorResp.MinAcceptDepth
        }

        // We'll ignore the min_depth calculated above if this is a zero-conf
        // channel.
        if zeroConf {
                numConfsReq = 0
        }

        reservation.SetNumConfsRequired(numConfsReq)

        // We'll also validate and apply all the constraints the initiating
        // party is attempting to dictate for our commitment transaction.
        stateBounds := &channeldb.ChannelStateBounds{
                ChanReserve:      msg.ChannelReserve,
                MaxPendingAmount: msg.MaxValueInFlight,
                MinHTLC:          msg.HtlcMinimum,
                MaxAcceptedHtlcs: msg.MaxAcceptedHTLCs,
        }
        commitParams := &channeldb.CommitmentParams{
                DustLimit: msg.DustLimit,
                CsvDelay:  msg.CsvDelay,
        }
        err = reservation.CommitConstraints(
                stateBounds, commitParams, f.cfg.MaxLocalCSVDelay, true,
        )
        if err != nil {
                log.Errorf("Unacceptable channel constraints: %v", err)
                f.failFundingFlow(peer, cid, err)
                return
        }

        // Check whether the peer supports upfront shutdown, and get a new
        // wallet address if our node is configured to set shutdown addresses by
        // default. We use the upfront shutdown script provided by our channel
        // acceptor (if any) in lieu of user input.
        shutdown, err := getUpfrontShutdownScript(
                f.cfg.EnableUpfrontShutdown, peer, acceptorResp.UpfrontShutdown,
                f.selectShutdownScript,
        )
        if err != nil {
                f.failFundingFlow(
                        peer, cid,
                        fmt.Errorf("getUpfrontShutdownScript error: %w", err),
                )
                return
        }
        reservation.SetOurUpfrontShutdown(shutdown)

        // If a script enforced channel lease is being proposed, we'll need to
        // validate its custom TLV records.
        if commitType == lnwallet.CommitmentTypeScriptEnforcedLease {
                if msg.LeaseExpiry == nil {
                        err := errors.New("missing lease expiry")
                        f.failFundingFlow(peer, cid, err)
                        return
                }

                // If we had a shim registered for this channel prior to
                // receiving its corresponding OpenChannel message, then we'll
                // validate the proposed LeaseExpiry against what was registered
                // in our shim.
                if reservation.LeaseExpiry() != 0 {
                        if uint32(*msg.LeaseExpiry) !=
                                reservation.LeaseExpiry() {

                                err := errors.New("lease expiry mismatch")
                                f.failFundingFlow(peer, cid, err)
                                return
                        }
                }
        }

        log.Infof("Requiring %v confirmations for pendingChan(%x): "+
                "amt=%v, push_amt=%v, committype=%v, upfrontShutdown=%x",
                numConfsReq, msg.PendingChannelID, amt, msg.PushAmount,
                commitType, msg.UpfrontShutdownScript)

        // Generate our required constraints for the remote party, using the
        // values provided by the channel acceptor if they are non-zero.
        remoteCsvDelay := f.cfg.RequiredRemoteDelay(amt)
        if acceptorResp.CSVDelay != 0 {
                remoteCsvDelay = acceptorResp.CSVDelay
        }

        // If our default dust limit was above their ChannelReserve, we change
        // it to the ChannelReserve. We must make sure the ChannelReserve we
        // send in the AcceptChannel message is above both dust limits.
        // Therefore, take the maximum of msg.DustLimit and our dust limit.
        //
        // NOTE: Even with this bounding, the ChannelAcceptor may return an
        // BOLT#02-invalid ChannelReserve.
        maxDustLimit := reservation.OurContribution().DustLimit
        if msg.DustLimit > maxDustLimit {
                maxDustLimit = msg.DustLimit
        }

        chanReserve := f.cfg.RequiredRemoteChanReserve(amt, maxDustLimit)
        if acceptorResp.Reserve != 0 {
                chanReserve = acceptorResp.Reserve
        }

        remoteMaxValue := f.cfg.RequiredRemoteMaxValue(amt)
        if acceptorResp.InFlightTotal != 0 {
                remoteMaxValue = acceptorResp.InFlightTotal
        }

        maxHtlcs := f.cfg.RequiredRemoteMaxHTLCs(amt)
        if acceptorResp.HtlcLimit != 0 {
                maxHtlcs = acceptorResp.HtlcLimit
        }

        // Default to our default minimum hltc value, replacing it with the
        // channel acceptor's value if it is set.
        minHtlc := f.cfg.DefaultMinHtlcIn
        if acceptorResp.MinHtlcIn != 0 {
                minHtlc = acceptorResp.MinHtlcIn
        }

        // If we are handling a FundingOpen request then we need to specify the
        // default channel fees since they are not provided by the responder
        // interactively.
        ourContribution := reservation.OurContribution()
        forwardingPolicy := f.defaultForwardingPolicy(
                ourContribution.ChannelStateBounds,
        )

        // Once the reservation has been created successfully, we add it to
        // this peer's map of pending reservations to track this particular
        // reservation until either abort or completion.
        f.resMtx.Lock()
        if _, ok := f.activeReservations[peerIDKey]; !ok {
                f.activeReservations[peerIDKey] = make(pendingChannels)
        }
        resCtx := &reservationWithCtx{
                reservation:       reservation,
                chanAmt:           amt,
                forwardingPolicy:  *forwardingPolicy,
                remoteCsvDelay:    remoteCsvDelay,
                remoteMinHtlc:     minHtlc,
                remoteMaxValue:    remoteMaxValue,
                remoteMaxHtlcs:    maxHtlcs,
                remoteChanReserve: chanReserve,
                maxLocalCsv:       f.cfg.MaxLocalCSVDelay,
                channelType:       chanType,
                err:               make(chan error, 1),
                peer:              peer,
        }
        f.activeReservations[peerIDKey][msg.PendingChannelID] = resCtx
        f.resMtx.Unlock()

        // Update the timestamp once the fundingOpenMsg has been handled.
        defer resCtx.updateTimestamp()

        cfg := channeldb.ChannelConfig{
                ChannelStateBounds: channeldb.ChannelStateBounds{
                        MaxPendingAmount: remoteMaxValue,
                        ChanReserve:      chanReserve,
                        MinHTLC:          minHtlc,
                        MaxAcceptedHtlcs: maxHtlcs,
                },
                CommitmentParams: channeldb.CommitmentParams{
                        DustLimit: msg.DustLimit,
                        CsvDelay:  remoteCsvDelay,
                },
                MultiSigKey: keychain.KeyDescriptor{
                        PubKey: copyPubKey(msg.FundingKey),
                },
                RevocationBasePoint: keychain.KeyDescriptor{
                        PubKey: copyPubKey(msg.RevocationPoint),
                },
                PaymentBasePoint: keychain.KeyDescriptor{
                        PubKey: copyPubKey(msg.PaymentPoint),
                },
                DelayBasePoint: keychain.KeyDescriptor{
                        PubKey: copyPubKey(msg.DelayedPaymentPoint),
                },
                HtlcBasePoint: keychain.KeyDescriptor{
                        PubKey: copyPubKey(msg.HtlcPoint),
                },
        }

        // With our parameters set, we'll now process their contribution so we
        // can move the funding workflow ahead.
        remoteContribution := &lnwallet.ChannelContribution{
                FundingAmount:        amt,
                FirstCommitmentPoint: msg.FirstCommitmentPoint,
                ChannelConfig:        &cfg,
                UpfrontShutdown:      msg.UpfrontShutdownScript,
        }

        if resCtx.reservation.IsTaproot() {
                localNonce, err := msg.LocalNonce.UnwrapOrErrV(errNoLocalNonce)
                if err != nil {
                        log.Error(errNoLocalNonce)

                        f.failFundingFlow(resCtx.peer, cid, errNoLocalNonce)

                        return
                }

                remoteContribution.LocalNonce = &musig2.Nonces{
                        PubNonce: localNonce,
                }
        }

        err = reservation.ProcessSingleContribution(remoteContribution)
        if err != nil {
                log.Errorf("unable to add contribution reservation: %v", err)
                f.failFundingFlow(peer, cid, err)
                return
        }

        log.Infof("Sending fundingResp for pending_id(%x)",
                msg.PendingChannelID)
        bounds := remoteContribution.ChannelConfig.ChannelStateBounds
        log.Debugf("Remote party accepted channel state space bounds: %v",
                lnutils.SpewLogClosure(bounds))
        params := remoteContribution.ChannelConfig.CommitmentParams
        log.Debugf("Remote party accepted commitment rendering params: %v",
                lnutils.SpewLogClosure(params))

        reservation.SetState(lnwallet.SentAcceptChannel)

        // With the initiator's contribution recorded, respond with our
        // contribution in the next message of the workflow.
        fundingAccept := lnwire.AcceptChannel{
                PendingChannelID:      msg.PendingChannelID,
                DustLimit:             ourContribution.DustLimit,
                MaxValueInFlight:      remoteMaxValue,
                ChannelReserve:        chanReserve,
                MinAcceptDepth:        uint32(numConfsReq),
                HtlcMinimum:           minHtlc,
                CsvDelay:              remoteCsvDelay,
                MaxAcceptedHTLCs:      maxHtlcs,
                FundingKey:            ourContribution.MultiSigKey.PubKey,
                RevocationPoint:       ourContribution.RevocationBasePoint.PubKey,
                PaymentPoint:          ourContribution.PaymentBasePoint.PubKey,
                DelayedPaymentPoint:   ourContribution.DelayBasePoint.PubKey,
                HtlcPoint:             ourContribution.HtlcBasePoint.PubKey,
                FirstCommitmentPoint:  ourContribution.FirstCommitmentPoint,
                UpfrontShutdownScript: ourContribution.UpfrontShutdown,
                ChannelType:           chanType,
                LeaseExpiry:           msg.LeaseExpiry,
        }

        if commitType.IsTaproot() {
                fundingAccept.LocalNonce = lnwire.SomeMusig2Nonce(
                        ourContribution.LocalNonce.PubNonce,
                )
        }

        if err := peer.SendMessage(true, &fundingAccept); err != nil {
                log.Errorf("unable to send funding response to peer: %v", err)
                f.failFundingFlow(peer, cid, err)
                return
        }
}

// funderProcessAcceptChannel processes a response to the workflow initiation
// sent by the remote peer. This message then queues a message with the funding
// outpoint, and a commitment signature to the remote peer.
//
//nolint:funlen
func (f *Manager) funderProcessAcceptChannel(peer lnpeer.Peer,
        msg *lnwire.AcceptChannel) {

        pendingChanID := msg.PendingChannelID
        peerKey := peer.IdentityKey()
        var peerKeyBytes []byte
        if peerKey != nil {
                peerKeyBytes = peerKey.SerializeCompressed()
        }

        resCtx, err := f.getReservationCtx(peerKey, pendingChanID)
        if err != nil {
                log.Warnf("Can't find reservation (peerKey:%x, chan_id:%v)",
                        peerKeyBytes, pendingChanID)
                return
        }

        // Update the timestamp once the fundingAcceptMsg has been handled.
        defer resCtx.updateTimestamp()

        if resCtx.reservation.State() != lnwallet.SentOpenChannel {
                return
        }

        log.Infof("Recv'd fundingResponse for pending_id(%x)",
                pendingChanID[:])

        // Create the channel identifier.
        cid := newChanIdentifier(msg.PendingChannelID)

        // Perform some basic validation of any custom TLV records included.
        //
        // TODO: Return errors as funding.Error to give context to remote peer?
        if resCtx.channelType != nil {
                // We'll want to quickly check that the ChannelType echoed by
                // the channel request recipient matches what we proposed.
                if msg.ChannelType == nil {
                        err := errors.New("explicit channel type not echoed " +
                                "back")
                        f.failFundingFlow(peer, cid, err)
                        return
                }
                proposedFeatures := lnwire.RawFeatureVector(*resCtx.channelType)
                ackedFeatures := lnwire.RawFeatureVector(*msg.ChannelType)
                if !proposedFeatures.Equals(&ackedFeatures) {
                        err := errors.New("channel type mismatch")
                        f.failFundingFlow(peer, cid, err)
                        return
                }

                // We'll want to do the same with the LeaseExpiry if one should
                // be set.
                if resCtx.reservation.LeaseExpiry() != 0 {
                        if msg.LeaseExpiry == nil {
                                err := errors.New("lease expiry not echoed " +
                                        "back")
                                f.failFundingFlow(peer, cid, err)
                                return
                        }
                        if uint32(*msg.LeaseExpiry) !=
                                resCtx.reservation.LeaseExpiry() {

                                err := errors.New("lease expiry mismatch")
                                f.failFundingFlow(peer, cid, err)
                                return
                        }
                }
        } else if msg.ChannelType != nil {
                // The spec isn't too clear about whether it's okay to set the
                // channel type in the accept_channel response if we didn't
                // explicitly set it in the open_channel message. For now, we
                // check that it's the same type we'd have arrived through
                // implicit negotiation. If it's another type, we fail the flow.
                _, implicitCommitType := implicitNegotiateCommitmentType(
                        peer.LocalFeatures(), peer.RemoteFeatures(),
                )

                _, negotiatedCommitType, err := negotiateCommitmentType(
                        msg.ChannelType, peer.LocalFeatures(),
                        peer.RemoteFeatures(),
                )
                if err != nil {
                        err := errors.New("received unexpected channel type")
                        f.failFundingFlow(peer, cid, err)
                        return
                }

                if implicitCommitType != negotiatedCommitType {
                        err := errors.New("negotiated unexpected channel type")
                        f.failFundingFlow(peer, cid, err)
                        return
                }
        }

        // The required number of confirmations should not be greater than the
        // maximum number of confirmations required by the ChainNotifier to
        // properly dispatch confirmations.
        if msg.MinAcceptDepth > chainntnfs.MaxNumConfs {
                err := lnwallet.ErrNumConfsTooLarge(
                        msg.MinAcceptDepth, chainntnfs.MaxNumConfs,
                )
                log.Warnf("Unacceptable channel constraints: %v", err)
                f.failFundingFlow(peer, cid, err)
                return
        }

        // Check that zero-conf channels have minimum depth set to 0.
        if resCtx.reservation.IsZeroConf() && msg.MinAcceptDepth != 0 {
                err = fmt.Errorf("zero-conf channel has min_depth non-zero")
                log.Warn(err)
                f.failFundingFlow(peer, cid, err)
                return
        }

        // If this is not a zero-conf channel but the peer responded with a
        // min-depth of zero, we will use our minimum of 1 instead.
        minDepth := msg.MinAcceptDepth
        if !resCtx.reservation.IsZeroConf() && minDepth == 0 {
                log.Infof("Responder to pending_id=%v sent a minimum "+
                        "confirmation depth of 0 for non-zero-conf channel. "+
                        "We will use a minimum depth of 1 instead.",
                        cid.tempChanID)

                minDepth = 1
        }

        // We'll also specify the responder's preference for the number of
        // required confirmations, and also the set of channel constraints
        // they've specified for commitment states we can create.
        resCtx.reservation.SetNumConfsRequired(uint16(minDepth))
        bounds := channeldb.ChannelStateBounds{
                ChanReserve:      msg.ChannelReserve,
                MaxPendingAmount: msg.MaxValueInFlight,
                MinHTLC:          msg.HtlcMinimum,
                MaxAcceptedHtlcs: msg.MaxAcceptedHTLCs,
        }
        commitParams := channeldb.CommitmentParams{
                DustLimit: msg.DustLimit,
                CsvDelay:  msg.CsvDelay,
        }
        err = resCtx.reservation.CommitConstraints(
                &bounds, &commitParams, resCtx.maxLocalCsv, false,
        )
        if err != nil {
                log.Warnf("Unacceptable channel constraints: %v", err)
                f.failFundingFlow(peer, cid, err)
                return
        }

        cfg := channeldb.ChannelConfig{
                ChannelStateBounds: channeldb.ChannelStateBounds{
                        MaxPendingAmount: resCtx.remoteMaxValue,
                        ChanReserve:      resCtx.remoteChanReserve,
                        MinHTLC:          resCtx.remoteMinHtlc,
                        MaxAcceptedHtlcs: resCtx.remoteMaxHtlcs,
                },
                CommitmentParams: channeldb.CommitmentParams{
                        DustLimit: msg.DustLimit,
                        CsvDelay:  resCtx.remoteCsvDelay,
                },
                MultiSigKey: keychain.KeyDescriptor{
                        PubKey: copyPubKey(msg.FundingKey),
                },
                RevocationBasePoint: keychain.KeyDescriptor{
                        PubKey: copyPubKey(msg.RevocationPoint),
                },
                PaymentBasePoint: keychain.KeyDescriptor{
                        PubKey: copyPubKey(msg.PaymentPoint),
                },
                DelayBasePoint: keychain.KeyDescriptor{
                        PubKey: copyPubKey(msg.DelayedPaymentPoint),
                },
                HtlcBasePoint: keychain.KeyDescriptor{
                        PubKey: copyPubKey(msg.HtlcPoint),
                },
        }

        // The remote node has responded with their portion of the channel
        // contribution. At this point, we can process their contribution which
        // allows us to construct and sign both the commitment transaction, and
        // the funding transaction.
        remoteContribution := &lnwallet.ChannelContribution{
                FirstCommitmentPoint: msg.FirstCommitmentPoint,
                ChannelConfig:        &cfg,
                UpfrontShutdown:      msg.UpfrontShutdownScript,
        }

        if resCtx.reservation.IsTaproot() {
                localNonce, err := msg.LocalNonce.UnwrapOrErrV(errNoLocalNonce)
                if err != nil {
                        log.Error(errNoLocalNonce)

                        f.failFundingFlow(resCtx.peer, cid, errNoLocalNonce)

                        return
                }

                remoteContribution.LocalNonce = &musig2.Nonces{
                        PubNonce: localNonce,
                }
        }

        err = resCtx.reservation.ProcessContribution(remoteContribution)

        // The wallet has detected that a PSBT funding process was requested by
        // the user and has halted the funding process after negotiating the
        // multisig keys. We now have everything that is needed for the user to
        // start constructing a PSBT that sends to the multisig funding address.
        var psbtIntent *chanfunding.PsbtIntent
        if psbtErr, ok := err.(*lnwallet.PsbtFundingRequired); ok {
                // Return the information that is needed by the user to
                // construct the PSBT back to the caller.
                addr, amt, packet, err := psbtErr.Intent.FundingParams()
                if err != nil {
                        log.Errorf("Unable to process PSBT funding params "+
                                "for contribution from %x: %v", peerKeyBytes,
                                err)
                        f.failFundingFlow(peer, cid, err)
                        return
                }
                var buf bytes.Buffer
                err = packet.Serialize(&buf)
                if err != nil {
                        log.Errorf("Unable to serialize PSBT for "+
                                "contribution from %x: %v", peerKeyBytes, err)
                        f.failFundingFlow(peer, cid, err)
                        return
                }
                resCtx.updates <- &lnrpc.OpenStatusUpdate{
                        PendingChanId: pendingChanID[:],
                        Update: &lnrpc.OpenStatusUpdate_PsbtFund{
                                PsbtFund: &lnrpc.ReadyForPsbtFunding{
                                        FundingAddress: addr.EncodeAddress(),
                                        FundingAmount:  amt,
                                        Psbt:           buf.Bytes(),
                                },
                        },
                }
                psbtIntent = psbtErr.Intent
        } else if err != nil {
                log.Errorf("Unable to process contribution from %x: %v",
                        peerKeyBytes, err)
                f.failFundingFlow(peer, cid, err)
                return
        }

        log.Infof("pendingChan(%x): remote party proposes num_confs=%v, "+
                "csv_delay=%v", pendingChanID[:], msg.MinAcceptDepth,
                msg.CsvDelay)
        bounds = remoteContribution.ChannelConfig.ChannelStateBounds
        log.Debugf("Remote party accepted channel state space bounds: %v",
                lnutils.SpewLogClosure(bounds))
        commitParams = remoteContribution.ChannelConfig.CommitmentParams
        log.Debugf("Remote party accepted commitment rendering params: %v",
                lnutils.SpewLogClosure(commitParams))

        // If the user requested funding through a PSBT, we cannot directly
        // continue now and need to wait for the fully funded and signed PSBT
        // to arrive. To not block any other channels from opening, we wait in
        // a separate goroutine.
        if psbtIntent != nil {
                f.wg.Add(1)
                go func() {
                        defer f.wg.Done()

                        f.waitForPsbt(psbtIntent, resCtx, cid)
                }()

                // With the new goroutine spawned, we can now exit to unblock
                // the main event loop.
                return
        }

        // In a normal, non-PSBT funding flow, we can jump directly to the next
        // step where we expect our contribution to be finalized.
        f.continueFundingAccept(resCtx, cid)
}

// waitForPsbt blocks until either a signed PSBT arrives, an error occurs or
// the funding manager shuts down. In the case of a valid PSBT, the funding flow
// is continued.
//
// NOTE: This method must be called as a goroutine.
func (f *Manager) waitForPsbt(intent *chanfunding.PsbtIntent,
        resCtx *reservationWithCtx, cid *chanIdentifier) {

        // failFlow is a helper that logs an error message with the current
        // context and then fails the funding flow.
        peerKey := resCtx.peer.IdentityKey()
        failFlow := func(errMsg string, cause error) {
                log.Errorf("Unable to handle funding accept message "+
                        "for peer_key=%x, pending_chan_id=%x: %s: %v",
                        peerKey.SerializeCompressed(), cid.tempChanID, errMsg,
                        cause)
                f.failFundingFlow(resCtx.peer, cid, cause)
        }

        // We'll now wait until the intent has received the final and complete
        // funding transaction. If the channel is closed without any error being
        // sent, we know everything's going as expected.
        select {
        case err := <-intent.PsbtReady:
                switch err {
                // If the user canceled the funding reservation, we need to
                // inform the other peer about us canceling the reservation.
                case chanfunding.ErrUserCanceled:
                        failFlow("aborting PSBT flow", err)
                        return

                // If the remote canceled the funding reservation, we don't need
                // to send another fail message. But we want to inform the user
                // about what happened.
                case chanfunding.ErrRemoteCanceled:
                        log.Infof("Remote canceled, aborting PSBT flow "+
                                "for peer_key=%x, pending_chan_id=%x",
                                peerKey.SerializeCompressed(), cid.tempChanID)
                        return

                // Nil error means the flow continues normally now.
                case nil:

                // For any other error, we'll fail the funding flow.
                default:
                        failFlow("error waiting for PSBT flow", err)
                        return
                }

                // At this point, we'll see if there's an AuxFundingDesc we
                // need to deliver so the funding process can continue
                // properly.
                auxFundingDesc, err := fn.MapOptionZ(
                        f.cfg.AuxFundingController,
                        func(c AuxFundingController) AuxFundingDescResult {
                                return c.DescFromPendingChanID(
                                        cid.tempChanID,
                                        lnwallet.NewAuxChanState(
                                                resCtx.reservation.ChanState(),
                                        ),
                                        resCtx.reservation.CommitmentKeyRings(),
                                        true,
                                )
                        },
                ).Unpack()
                if err != nil {
                        failFlow("error continuing PSBT flow", err)
                        return
                }

                // A non-nil error means we can continue the funding flow.
                // Notify the wallet so it can prepare everything we need to
                // continue.
                //
                // We'll also pass along the aux funding controller as well,
                // which may be used to help process the finalized PSBT.
                err = resCtx.reservation.ProcessPsbt(auxFundingDesc)
                if err != nil {
                        failFlow("error continuing PSBT flow", err)
                        return
                }

                // We are now ready to continue the funding flow.
                f.continueFundingAccept(resCtx, cid)

        // Handle a server shutdown as well because the reservation won't
        // survive a restart as it's in memory only.
        case <-f.quit:
                log.Errorf("Unable to handle funding accept message "+
                        "for peer_key=%x, pending_chan_id=%x: funding manager "+
                        "shutting down", peerKey.SerializeCompressed(),
                        cid.tempChanID)
                return
        }
}

// continueFundingAccept continues the channel funding flow once our
// contribution is finalized, the channel output is known and the funding
// transaction is signed.
func (f *Manager) continueFundingAccept(resCtx *reservationWithCtx,
        cid *chanIdentifier) {

        // Now that we have their contribution, we can extract, then send over
        // both the funding out point and our signature for their version of
        // the commitment transaction to the remote peer.
        outPoint := resCtx.reservation.FundingOutpoint()
        _, sig := resCtx.reservation.OurSignatures()

        // A new channel has almost finished the funding process. In order to
        // properly synchronize with the writeHandler goroutine, we add a new
        // channel to the barriers map which will be closed once the channel is
        // fully open.
        channelID := lnwire.NewChanIDFromOutPoint(*outPoint)
        log.Debugf("Creating chan barrier for ChanID(%v)", channelID)

        // The next message that advances the funding flow will reference the
        // channel via its permanent channel ID, so we'll set up this mapping
        // so we can retrieve the reservation context once we get the
        // FundingSigned message.
        f.resMtx.Lock()
        f.signedReservations[channelID] = cid.tempChanID
        f.resMtx.Unlock()

        log.Infof("Generated ChannelPoint(%v) for pending_id(%x)", outPoint,
                cid.tempChanID[:])

        // Before sending FundingCreated sent, we notify Brontide to keep track
        // of this pending open channel.
        err := resCtx.peer.AddPendingChannel(channelID, f.quit)
        if err != nil {
                pubKey := resCtx.peer.IdentityKey().SerializeCompressed()
                log.Errorf("Unable to add pending channel %v with peer %x: %v",
                        channelID, pubKey, err)
        }

        // Once Brontide is aware of this channel, we need to set it in
        // chanIdentifier so this channel will be removed from Brontide if the
        // funding flow fails.
        cid.setChanID(channelID)

        // Send the FundingCreated msg.
        fundingCreated := &lnwire.FundingCreated{
                PendingChannelID: cid.tempChanID,
                FundingPoint:     *outPoint,
        }

        // If this is a taproot channel, then we'll need to populate the musig2
        // partial sig field instead of the regular commit sig field.
        if resCtx.reservation.IsTaproot() {
                partialSig, ok := sig.(*lnwallet.MusigPartialSig)
                if !ok {
                        err := fmt.Errorf("expected musig partial sig, got %T",
                                sig)
                        log.Error(err)
                        f.failFundingFlow(resCtx.peer, cid, err)

                        return
                }

                fundingCreated.PartialSig = lnwire.MaybePartialSigWithNonce(
                        partialSig.ToWireSig(),
                )
        } else {
                fundingCreated.CommitSig, err = lnwire.NewSigFromSignature(sig)
                if err != nil {
                        log.Errorf("Unable to parse signature: %v", err)
                        f.failFundingFlow(resCtx.peer, cid, err)
                        return
                }
        }

        resCtx.reservation.SetState(lnwallet.SentFundingCreated)

        if err := resCtx.peer.SendMessage(true, fundingCreated); err != nil {
                log.Errorf("Unable to send funding complete message: %v", err)
                f.failFundingFlow(resCtx.peer, cid, err)
                return
        }
}

// fundeeProcessFundingCreated progresses the funding workflow when the daemon
// is on the responding side of a single funder workflow. Once this message has
// been processed, a signature is sent to the remote peer allowing it to
// broadcast the funding transaction, progressing the workflow into the final
// stage.
//
//nolint:funlen
func (f *Manager) fundeeProcessFundingCreated(peer lnpeer.Peer,
        msg *lnwire.FundingCreated) {

        peerKey := peer.IdentityKey()
        pendingChanID := msg.PendingChannelID

        resCtx, err := f.getReservationCtx(peerKey, pendingChanID)
        if err != nil {
                log.Warnf("can't find reservation (peer_id:%v, chan_id:%x)",
                        peerKey, pendingChanID[:])
                return
        }

        // The channel initiator has responded with the funding outpoint of the
        // final funding transaction, as well as a signature for our version of
        // the commitment transaction. So at this point, we can validate the
        // initiator's commitment transaction, then send our own if it's valid.
        fundingOut := msg.FundingPoint
        log.Infof("completing pending_id(%x) with ChannelPoint(%v)",
                pendingChanID[:], fundingOut)

        if resCtx.reservation.State() != lnwallet.SentAcceptChannel {
                return
        }

        // Create the channel identifier without setting the active channel ID.
        cid := newChanIdentifier(pendingChanID)

        // For taproot channels, the commit signature is actually the partial
        // signature. Otherwise, we can convert the ECDSA commit signature into
        // our internal input.Signature type.
        var commitSig input.Signature
        if resCtx.reservation.IsTaproot() {
                partialSig, err := msg.PartialSig.UnwrapOrErrV(errNoPartialSig)
                if err != nil {
                        f.failFundingFlow(peer, cid, err)

                        return
                }

                commitSig = new(lnwallet.MusigPartialSig).FromWireSig(
                        &partialSig,
                )
        } else {
                commitSig, err = msg.CommitSig.ToSignature()
                if err != nil {
                        log.Errorf("unable to parse signature: %v", err)
                        f.failFundingFlow(peer, cid, err)
                        return
                }
        }

        // At this point, we'll see if there's an AuxFundingDesc we need to
        // deliver so the funding process can continue properly.
        auxFundingDesc, err := fn.MapOptionZ(
                f.cfg.AuxFundingController,
                func(c AuxFundingController) AuxFundingDescResult {
                        return c.DescFromPendingChanID(
                                cid.tempChanID, lnwallet.NewAuxChanState(
                                        resCtx.reservation.ChanState(),
                                ), resCtx.reservation.CommitmentKeyRings(),
                                true,
                        )
                },
        ).Unpack()
        if err != nil {
                log.Errorf("error continuing PSBT flow: %v", err)
                f.failFundingFlow(peer, cid, err)
                return
        }

        // With all the necessary data available, attempt to advance the
        // funding workflow to the next stage. If this succeeds then the
        // funding transaction will broadcast after our next message.
        // CompleteReservationSingle will also mark the channel as 'IsPending'
        // in the database.
        //
        // We'll also directly pass in the AuxFunding controller as well,
        // which may be used by the reservation system to finalize funding our
        // side.
        completeChan, err := resCtx.reservation.CompleteReservationSingle(
                &fundingOut, commitSig, auxFundingDesc,
        )
        if err != nil {
                log.Errorf("unable to complete single reservation: %v", err)
                f.failFundingFlow(peer, cid, err)
                return
        }

        // Get forwarding policy before deleting the reservation context.
        forwardingPolicy := resCtx.forwardingPolicy

        // The channel is marked IsPending in the database, and can be removed
        // from the set of active reservations.
        f.deleteReservationCtx(peerKey, cid.tempChanID)

        // If something goes wrong before the funding transaction is confirmed,
        // we use this convenience method to delete the pending OpenChannel
        // from the database.
        deleteFromDatabase := func() {
                localBalance := completeChan.LocalCommitment.LocalBalance.ToSatoshis()
                closeInfo := &channeldb.ChannelCloseSummary{
                        ChanPoint:               completeChan.FundingOutpoint,
                        ChainHash:               completeChan.ChainHash,
                        RemotePub:               completeChan.IdentityPub,
                        CloseType:               channeldb.FundingCanceled,
                        Capacity:                completeChan.Capacity,
                        SettledBalance:          localBalance,
                        RemoteCurrentRevocation: completeChan.RemoteCurrentRevocation,
                        RemoteNextRevocation:    completeChan.RemoteNextRevocation,
                        LocalChanConfig:         completeChan.LocalChanCfg,
                }

                // Close the channel with us as the initiator because we are
                // deciding to exit the funding flow due to an internal error.
                if err := completeChan.CloseChannel(
                        closeInfo, channeldb.ChanStatusLocalCloseInitiator,
                ); err != nil {
                        log.Errorf("Failed closing channel %v: %v",
                                completeChan.FundingOutpoint, err)
                }
        }

        // A new channel has almost finished the funding process. In order to
        // properly synchronize with the writeHandler goroutine, we add a new
        // channel to the barriers map which will be closed once the channel is
        // fully open.
        channelID := lnwire.NewChanIDFromOutPoint(fundingOut)
        log.Debugf("Creating chan barrier for ChanID(%v)", channelID)

        fundingSigned := &lnwire.FundingSigned{}

        // For taproot channels, we'll need to send over a partial signature
        // that includes the nonce along side the signature.
        _, sig := resCtx.reservation.OurSignatures()
        if resCtx.reservation.IsTaproot() {
                partialSig, ok := sig.(*lnwallet.MusigPartialSig)
                if !ok {
                        err := fmt.Errorf("expected musig partial sig, got %T",
                                sig)
                        log.Error(err)
                        f.failFundingFlow(resCtx.peer, cid, err)
                        deleteFromDatabase()

                        return
                }

                fundingSigned.PartialSig = lnwire.MaybePartialSigWithNonce(
                        partialSig.ToWireSig(),
                )
        } else {
                fundingSigned.CommitSig, err = lnwire.NewSigFromSignature(sig)
                if err != nil {
                        log.Errorf("unable to parse signature: %v", err)
                        f.failFundingFlow(peer, cid, err)
                        deleteFromDatabase()

                        return
                }
        }

        // Before sending FundingSigned, we notify Brontide first to keep track
        // of this pending open channel.
        if err := peer.AddPendingChannel(channelID, f.quit); err != nil {
                pubKey := peer.IdentityKey().SerializeCompressed()
                log.Errorf("Unable to add pending channel %v with peer %x: %v",
                        cid.chanID, pubKey, err)
        }

        // Once Brontide is aware of this channel, we need to set it in
        // chanIdentifier so this channel will be removed from Brontide if the
        // funding flow fails.
        cid.setChanID(channelID)

        fundingSigned.ChanID = cid.chanID

        log.Infof("sending FundingSigned for pending_id(%x) over "+
                "ChannelPoint(%v)", pendingChanID[:], fundingOut)

        // With their signature for our version of the commitment transaction
        // verified, we can now send over our signature to the remote peer.
        if err := peer.SendMessage(true, fundingSigned); err != nil {
                log.Errorf("unable to send FundingSigned message: %v", err)
                f.failFundingFlow(peer, cid, err)
                deleteFromDatabase()
                return
        }

        // With a permanent channel id established we can save the respective
        // forwarding policy in the database. In the channel announcement phase
        // this forwarding policy is retrieved and applied.
        err = f.saveInitialForwardingPolicy(cid.chanID, &forwardingPolicy)
        if err != nil {
                log.Errorf("Unable to store the forwarding policy: %v", err)
        }

        // Now that we've sent over our final signature for this channel, we'll
        // send it to the ChainArbitrator so it can watch for any on-chain
        // actions during this final confirmation stage.
        if err := f.cfg.WatchNewChannel(completeChan, peerKey); err != nil {
                log.Errorf("Unable to send new ChannelPoint(%v) for "+
                        "arbitration: %v", fundingOut, err)
        }

        // Create an entry in the local discovery map so we can ensure that we
        // process the channel confirmation fully before we receive a
        // channel_ready message.
        f.localDiscoverySignals.Store(cid.chanID, make(chan struct{}))

        // Inform the ChannelNotifier that the channel has entered
        // pending open state.
        f.cfg.NotifyPendingOpenChannelEvent(
                fundingOut, completeChan, completeChan.IdentityPub,
        )

        // At this point we have sent our last funding message to the
        // initiating peer before the funding transaction will be broadcast.
        // With this last message, our job as the responder is now complete.
        // We'll wait for the funding transaction to reach the specified number
        // of confirmations, then start normal operations.
        //
        // When we get to this point we have sent the signComplete message to
        // the channel funder, and BOLT#2 specifies that we MUST remember the
        // channel for reconnection. The channel is already marked
        // as pending in the database, so in case of a disconnect or restart,
        // we will continue waiting for the confirmation the next time we start
        // the funding manager. In case the funding transaction never appears
        // on the blockchain, we must forget this channel. We therefore
        // completely forget about this channel if we haven't seen the funding
        // transaction in 288 blocks (~ 48 hrs), by canceling the reservation
        // and canceling the wait for the funding confirmation.
        f.wg.Add(1)
        go f.advanceFundingState(completeChan, pendingChanID, nil)
}

// funderProcessFundingSigned processes the final message received in a single
// funder workflow. Once this message is processed, the funding transaction is
// broadcast. Once the funding transaction reaches a sufficient number of
// confirmations, a message is sent to the responding peer along with a compact
// encoding of the location of the channel within the blockchain.
func (f *Manager) funderProcessFundingSigned(peer lnpeer.Peer,
        msg *lnwire.FundingSigned) {

        // As the funding signed message will reference the reservation by its
        // permanent channel ID, we'll need to perform an intermediate look up
        // before we can obtain the reservation.
        f.resMtx.Lock()
        pendingChanID, ok := f.signedReservations[msg.ChanID]
        delete(f.signedReservations, msg.ChanID)
        f.resMtx.Unlock()

        // Create the channel identifier and set the channel ID.
        //
        // NOTE: we may get an empty pending channel ID here if the key cannot
        // be found, which means when we cancel the reservation context in
        // `failFundingFlow`, we will get an error. In this case, we will send
        // an error msg to our peer using the active channel ID.
        //
        // TODO(yy): refactor the funding flow to fix this case.
        cid := newChanIdentifier(pendingChanID)
        cid.setChanID(msg.ChanID)

        // If the pending channel ID is not found, fail the funding flow.
        if !ok {
                // NOTE: we directly overwrite the pending channel ID here for
                // this rare case since we don't have a valid pending channel
                // ID.
                cid.tempChanID = msg.ChanID

                err := fmt.Errorf("unable to find signed reservation for "+
                        "chan_id=%x", msg.ChanID)
                log.Warnf(err.Error())
                f.failFundingFlow(peer, cid, err)
                return
        }

        peerKey := peer.IdentityKey()
        resCtx, err := f.getReservationCtx(peerKey, pendingChanID)
        if err != nil {
                log.Warnf("Unable to find reservation (peer_id:%v, "+
                        "chan_id:%x)", peerKey, pendingChanID[:])
                // TODO: add ErrChanNotFound?
                f.failFundingFlow(peer, cid, err)
                return
        }

        if resCtx.reservation.State() != lnwallet.SentFundingCreated {
                err := fmt.Errorf("unable to find reservation for chan_id=%x",
                        msg.ChanID)
                f.failFundingFlow(peer, cid, err)

                return
        }

        // Create an entry in the local discovery map so we can ensure that we
        // process the channel confirmation fully before we receive a
        // channel_ready message.
        fundingPoint := resCtx.reservation.FundingOutpoint()
        permChanID := lnwire.NewChanIDFromOutPoint(*fundingPoint)
        f.localDiscoverySignals.Store(permChanID, make(chan struct{}))

        // We have to store the forwardingPolicy before the reservation context
        // is deleted. The policy will then be read and applied in
        // newChanAnnouncement.
        err = f.saveInitialForwardingPolicy(
                permChanID, &resCtx.forwardingPolicy,
        )
        if err != nil {
                log.Errorf("Unable to store the forwarding policy: %v", err)
        }

        // For taproot channels, the commit signature is actually the partial
        // signature. Otherwise, we can convert the ECDSA commit signature into
        // our internal input.Signature type.
        var commitSig input.Signature
        if resCtx.reservation.IsTaproot() {
                partialSig, err := msg.PartialSig.UnwrapOrErrV(errNoPartialSig)
                if err != nil {
                        f.failFundingFlow(peer, cid, err)

                        return
                }

                commitSig = new(lnwallet.MusigPartialSig).FromWireSig(
                        &partialSig,
                )
        } else {
                commitSig, err = msg.CommitSig.ToSignature()
                if err != nil {
                        log.Errorf("unable to parse signature: %v", err)
                        f.failFundingFlow(peer, cid, err)
                        return
                }
        }

        completeChan, err := resCtx.reservation.CompleteReservation(
                nil, commitSig,
        )
        if err != nil {
                log.Errorf("Unable to complete reservation sign "+
                        "complete: %v", err)
                f.failFundingFlow(peer, cid, err)
                return
        }

        // The channel is now marked IsPending in the database, and we can
        // delete it from our set of active reservations.
        f.deleteReservationCtx(peerKey, pendingChanID)

        // Broadcast the finalized funding transaction to the network, but only
        // if we actually have the funding transaction.
        if completeChan.ChanType.HasFundingTx() {
                fundingTx := completeChan.FundingTxn
                var fundingTxBuf bytes.Buffer
                if err := fundingTx.Serialize(&fundingTxBuf); err != nil {
                        log.Errorf("Unable to serialize funding "+
                                "transaction %v: %v", fundingTx.TxHash(), err)

                        // Clear the buffer of any bytes that were written
                        // before the serialization error to prevent logging an
                        // incomplete transaction.
                        fundingTxBuf.Reset()
                }

                log.Infof("Broadcasting funding tx for ChannelPoint(%v): %x",
                        completeChan.FundingOutpoint, fundingTxBuf.Bytes())

                // Set a nil short channel ID at this stage because we do not
                // know it until our funding tx confirms.
                label := labels.MakeLabel(
                        labels.LabelTypeChannelOpen, nil,
                )

                err = f.cfg.PublishTransaction(fundingTx, label)
                if err != nil {
                        log.Errorf("Unable to broadcast funding tx %x for "+
                                "ChannelPoint(%v): %v", fundingTxBuf.Bytes(),
                                completeChan.FundingOutpoint, err)

                        // We failed to broadcast the funding transaction, but
                        // watch the channel regardless, in case the
                        // transaction made it to the network. We will retry
                        // broadcast at startup.
                        //
                        // TODO(halseth): retry more often? Handle with CPFP?
                        // Just delete from the DB?
                }
        }

        // Before we proceed, if we have a funding hook that wants a
        // notification that it's safe to broadcast the funding transaction,
        // then we'll send that now.
        err = fn.MapOptionZ(
                f.cfg.AuxFundingController,
                func(controller AuxFundingController) error {
                        return controller.ChannelFinalized(cid.tempChanID)
                },
        )
        if err != nil {
                log.Errorf("Failed to inform aux funding controller about "+
                        "ChannelPoint(%v) being finalized: %v", fundingPoint,
                        err)
        }

        // Now that we have a finalized reservation for this funding flow,
        // we'll send the to be active channel to the ChainArbitrator so it can
        // watch for any on-chain actions before the channel has fully
        // confirmed.
        if err := f.cfg.WatchNewChannel(completeChan, peerKey); err != nil {
                log.Errorf("Unable to send new ChannelPoint(%v) for "+
                        "arbitration: %v", fundingPoint, err)
        }

        log.Infof("Finalizing pending_id(%x) over ChannelPoint(%v), "+
                "waiting for channel open on-chain", pendingChanID[:],
                fundingPoint)

        // Send an update to the upstream client that the negotiation process
        // is over.
        upd := &lnrpc.OpenStatusUpdate{
                Update: &lnrpc.OpenStatusUpdate_ChanPending{
                        ChanPending: &lnrpc.PendingUpdate{
                                Txid:        fundingPoint.Hash[:],
                                OutputIndex: fundingPoint.Index,
                        },
                },
                PendingChanId: pendingChanID[:],
        }

        select {
        case resCtx.updates <- upd:
                // Inform the ChannelNotifier that the channel has entered
                // pending open state.
                f.cfg.NotifyPendingOpenChannelEvent(
                        *fundingPoint, completeChan, completeChan.IdentityPub,
                )

        case <-f.quit:
                return
        }

        // At this point we have broadcast the funding transaction and done all
        // necessary processing.
        f.wg.Add(1)
        go f.advanceFundingState(completeChan, pendingChanID, resCtx.updates)
}

// confirmedChannel wraps a confirmed funding transaction, as well as the short
// channel ID which identifies that channel into a single struct. We'll use
// this to pass around the final state of a channel after it has been
// confirmed.
type confirmedChannel struct {
        // shortChanID expresses where in the block the funding transaction was
        // located.
        shortChanID lnwire.ShortChannelID

        // fundingTx is the funding transaction that created the channel.
        fundingTx *wire.MsgTx
}

// fundingTimeout is called when callers of waitForFundingWithTimeout receive
// an ErrConfirmationTimeout. It is used to clean-up channel state and mark the
// channel as closed. The error is only returned for the responder of the
// channel flow.
func (f *Manager) fundingTimeout(c *channeldb.OpenChannel,
        pendingID PendingChanID) error {

        // We'll get a timeout if the number of blocks mined since the channel
        // was initiated reaches MaxWaitNumBlocksFundingConf and we are not the
        // channel initiator.
        localBalance := c.LocalCommitment.LocalBalance.ToSatoshis()
        closeInfo := &channeldb.ChannelCloseSummary{
                ChainHash:               c.ChainHash,
                ChanPoint:               c.FundingOutpoint,
                RemotePub:               c.IdentityPub,
                Capacity:                c.Capacity,
                SettledBalance:          localBalance,
                CloseType:               channeldb.FundingCanceled,
                RemoteCurrentRevocation: c.RemoteCurrentRevocation,
                RemoteNextRevocation:    c.RemoteNextRevocation,
                LocalChanConfig:         c.LocalChanCfg,
        }

        // Close the channel with us as the initiator because we are timing the
        // channel out.
        if err := c.CloseChannel(
                closeInfo, channeldb.ChanStatusLocalCloseInitiator,
        ); err != nil {
                return fmt.Errorf("failed closing channel %v: %w",
                        c.FundingOutpoint, err)
        }

        // Notify other subsystems about the funding timeout.
        f.cfg.NotifyFundingTimeout(c.FundingOutpoint, c.IdentityPub)

        timeoutErr := fmt.Errorf("timeout waiting for funding tx (%v) to "+
                "confirm", c.FundingOutpoint)

        // When the peer comes online, we'll notify it that we are now
        // considering the channel flow canceled.
        f.wg.Add(1)
        go func() {
                defer f.wg.Done()

                peer, err := f.waitForPeerOnline(c.IdentityPub)
                switch err {
                // We're already shutting down, so we can just return.
                case ErrFundingManagerShuttingDown:
                        return

                // nil error means we continue on.
                case nil:

                // For unexpected errors, we print the error and still try to
                // fail the funding flow.
                default:
                        log.Errorf("Unexpected error while waiting for peer "+
                                "to come online: %v", err)
                }

                // Create channel identifier and set the channel ID.
                cid := newChanIdentifier(pendingID)
                cid.setChanID(lnwire.NewChanIDFromOutPoint(c.FundingOutpoint))

                // TODO(halseth): should this send be made
                // reliable?

                // The reservation won't exist at this point, but we'll send an
                // Error message over anyways with ChanID set to pendingID.
                f.failFundingFlow(peer, cid, timeoutErr)
        }()

        return timeoutErr
}

// waitForFundingWithTimeout is a wrapper around waitForFundingConfirmation and
// waitForTimeout that will return ErrConfirmationTimeout if we are not the
// channel initiator and the MaxWaitNumBlocksFundingConf has passed from the
// funding broadcast height. In case of confirmation, the short channel ID of
// the channel and the funding transaction will be returned.
func (f *Manager) waitForFundingWithTimeout(
        ch *channeldb.OpenChannel) (*confirmedChannel, error) {

        confChan := make(chan *confirmedChannel)
        timeoutChan := make(chan error, 1)
        cancelChan := make(chan struct{})

        f.wg.Add(1)
        go f.waitForFundingConfirmation(ch, cancelChan, confChan)

        // If we are not the initiator, we have no money at stake and will
        // timeout waiting for the funding transaction to confirm after a
        // while.
        if !ch.IsInitiator && !ch.IsZeroConf() {
                f.wg.Add(1)
                go f.waitForTimeout(ch, cancelChan, timeoutChan)
        }
        defer close(cancelChan)

        select {
        case err := <-timeoutChan:
                if err != nil {
                        return nil, err
                }
                return nil, ErrConfirmationTimeout

        case <-f.quit:
                // The fundingManager is shutting down, and will resume wait on
                // startup.
                return nil, ErrFundingManagerShuttingDown

        case confirmedChannel, ok := <-confChan:
                if !ok {
                        return nil, fmt.Errorf("waiting for funding" +
                                "confirmation failed")
                }
                return confirmedChannel, nil
        }
}

// makeFundingScript re-creates the funding script for the funding transaction
// of the target channel.
func makeFundingScript(channel *channeldb.OpenChannel) ([]byte, error) {
        localKey := channel.LocalChanCfg.MultiSigKey.PubKey
        remoteKey := channel.RemoteChanCfg.MultiSigKey.PubKey

        if channel.ChanType.IsTaproot() {
                pkScript, _, err := input.GenTaprootFundingScript(
                        localKey, remoteKey, int64(channel.Capacity),
                        channel.TapscriptRoot,
                )
                if err != nil {
                        return nil, err
                }

                return pkScript, nil
        }

        multiSigScript, err := input.GenMultiSigScript(
                localKey.SerializeCompressed(),
                remoteKey.SerializeCompressed(),
        )
        if err != nil {
                return nil, err
        }

        return input.WitnessScriptHash(multiSigScript)
}

// waitForFundingConfirmation handles the final stages of the channel funding
// process once the funding transaction has been broadcast. The primary
// function of waitForFundingConfirmation is to wait for blockchain
// confirmation, and then to notify the other systems that must be notified
// when a channel has become active for lightning transactions. It also updates
// the channel’s opening transaction block height in the database.
// The wait can be canceled by closing the cancelChan. In case of success,
// a *lnwire.ShortChannelID will be passed to confChan.
//
// NOTE: This MUST be run as a goroutine.
func (f *Manager) waitForFundingConfirmation(
        completeChan *channeldb.OpenChannel, cancelChan <-chan struct{},
        confChan chan<- *confirmedChannel) {

        defer f.wg.Done()
        defer close(confChan)

        // Register with the ChainNotifier for a notification once the funding
        // transaction reaches `numConfs` confirmations.
        txid := completeChan.FundingOutpoint.Hash
        fundingScript, err := makeFundingScript(completeChan)
        if err != nil {
                log.Errorf("unable to create funding script for "+
                        "ChannelPoint(%v): %v", completeChan.FundingOutpoint,
                        err)
                return
        }
        numConfs := uint32(completeChan.NumConfsRequired)

        // If the underlying channel is a zero-conf channel, we'll set numConfs
        // to 6, since it will be zero here.
        if completeChan.IsZeroConf() {
                numConfs = 6
        }

        confNtfn, err := f.cfg.Notifier.RegisterConfirmationsNtfn(
                &txid, fundingScript, numConfs,
                completeChan.BroadcastHeight(),
        )
        if err != nil {
                log.Errorf("Unable to register for confirmation of "+
                        "ChannelPoint(%v): %v", completeChan.FundingOutpoint,
                        err)
                return
        }

        log.Infof("Waiting for funding tx (%v) to reach %v confirmations",
                txid, numConfs)

        // Wait until the specified number of confirmations has been reached,
        // we get a cancel signal, or the wallet signals a shutdown.
        for {
                select {
                case updDetails, ok := <-confNtfn.Updates:
                        if !ok {
                                log.Warnf("ChainNotifier shutting down, "+
                                        "cannot process updates for "+
                                        "ChannelPoint(%v)",
                                        completeChan.FundingOutpoint)

                                return
                        }

                        log.Debugf("funding tx %s received confirmation in "+
                                "block %d, %d confirmations left", txid,
                                updDetails.BlockHeight, updDetails.NumConfsLeft)

                        // Only update the ConfirmationHeight the first time a
                        // confirmation is received, since on subsequent
                        // confirmations the block height will remain the same.
                        if completeChan.ConfirmationHeight == 0 {
                                err := completeChan.MarkConfirmationHeight(
                                        updDetails.BlockHeight,
                                )
                                if err != nil {
                                        log.Errorf("failed to update "+
                                                "confirmed state for "+
                                                "ChannelPoint(%v): %v",
                                                completeChan.FundingOutpoint,
                                                err)

                                        return
                                }
                        }

                case _, ok := <-confNtfn.NegativeConf:
                        if !ok {
                                log.Warnf("ChainNotifier shutting down, "+
                                        "cannot track negative confirmations "+
                                        "for ChannelPoint(%v)",
                                        completeChan.FundingOutpoint)

                                return
                        }

                        log.Warnf("funding tx %s was reorged out; channel "+
                                "point: %s", txid, completeChan.FundingOutpoint)

                        // Reset the confirmation height to 0 because the
                        // funding transaction was reorged out.
                        err := completeChan.MarkConfirmationHeight(uint32(0))
                        if err != nil {
                                log.Errorf("failed to update state for "+
                                        "ChannelPoint(%v): %v",
                                        completeChan.FundingOutpoint, err)

                                return
                        }

                case confDetails, ok := <-confNtfn.Confirmed:
                        if !ok {
                                log.Warnf("ChainNotifier shutting down, "+
                                        "cannot complete funding flow for "+
                                        "ChannelPoint(%v)",
                                        completeChan.FundingOutpoint)

                                return
                        }

                        log.Debugf("funding tx %s for ChannelPoint(%v) "+
                                "confirmed in block %d", txid,
                                completeChan.FundingOutpoint,
                                confDetails.BlockHeight)

                        // In the case of requiring a single confirmation, it
                        // can happen that the `Confirmed` channel is read
                        // from first, in which case the confirmation height
                        // will not be set. If this happens, we take the
                        // confirmation height from the `Confirmed` channel.
                        if completeChan.ConfirmationHeight == 0 {
                                err := completeChan.MarkConfirmationHeight(
                                        confDetails.BlockHeight,
                                )
                                if err != nil {
                                        log.Errorf("failed to update "+
                                                "confirmed state for "+
                                                "ChannelPoint(%v): %v",
                                                completeChan.FundingOutpoint,
                                                err)

                                        return
                                }
                        }

                        err := f.handleConfirmation(
                                confDetails, completeChan, confChan,
                        )
                        if err != nil {
                                log.Errorf("Error handling confirmation for "+
                                        "ChannelPoint(%v), txid=%v: %v",
                                        completeChan.FundingOutpoint, txid, err)
                        }

                        return

                case <-cancelChan:
                        log.Warnf("canceled waiting for funding confirmation, "+
                                "stopping funding flow for ChannelPoint(%v)",
                                completeChan.FundingOutpoint)

                        return

                case <-f.quit:
                        log.Warnf("fundingManager shutting down, stopping "+
                                "funding flow for ChannelPoint(%v)",
                                completeChan.FundingOutpoint)

                        return
                }
        }
}

// handleConfirmation is a helper function that constructs a ShortChannelID
// based on the confirmation details and sends this information, along with the
// funding transaction, to the provided confirmation channel.
func (f *Manager) handleConfirmation(confDetails *chainntnfs.TxConfirmation,
        completeChan *channeldb.OpenChannel,
        confChan chan<- *confirmedChannel) error {

        fundingPoint := completeChan.FundingOutpoint
        log.Infof("ChannelPoint(%v) is now active: ChannelID(%v)",
                fundingPoint, lnwire.NewChanIDFromOutPoint(fundingPoint))

        // With the block height and the transaction index known, we can
        // construct the compact chanID which is used on the network to unique
        // identify channels.
        shortChanID := lnwire.ShortChannelID{
                BlockHeight: confDetails.BlockHeight,
                TxIndex:     confDetails.TxIndex,
                TxPosition:  uint16(fundingPoint.Index),
        }

        select {
        case confChan <- &confirmedChannel{
                shortChanID: shortChanID,
                fundingTx:   confDetails.Tx,
        }:
        case <-f.quit:
                return fmt.Errorf("manager shutting down")
        }

        return nil
}

// waitForTimeout will close the timeout channel if MaxWaitNumBlocksFundingConf
// has passed from the broadcast height of the given channel. In case of error,
// the error is sent on timeoutChan. The wait can be canceled by closing the
// cancelChan.
//
// NOTE: timeoutChan MUST be buffered.
// NOTE: This MUST be run as a goroutine.
func (f *Manager) waitForTimeout(completeChan *channeldb.OpenChannel,
        cancelChan <-chan struct{}, timeoutChan chan<- error) {

        defer f.wg.Done()

        epochClient, err := f.cfg.Notifier.RegisterBlockEpochNtfn(nil)
        if err != nil {
                timeoutChan <- fmt.Errorf("unable to register for epoch "+
                        "notification: %v", err)
                return
        }

        defer epochClient.Cancel()

        // The value of waitBlocksForFundingConf is adjusted in a development
        // environment to enhance test capabilities. Otherwise, it is set to
        // DefaultMaxWaitNumBlocksFundingConf.
        waitBlocksForFundingConf := uint32(
                lncfg.DefaultMaxWaitNumBlocksFundingConf,
        )

        if lncfg.IsDevBuild() {
                waitBlocksForFundingConf =
                        f.cfg.Dev.MaxWaitNumBlocksFundingConf
        }

        // On block maxHeight we will cancel the funding confirmation wait.
        broadcastHeight := completeChan.BroadcastHeight()
        maxHeight := broadcastHeight + waitBlocksForFundingConf
        for {
                select {
                case epoch, ok := <-epochClient.Epochs:
                        if !ok {
                                timeoutChan <- fmt.Errorf("epoch client " +
                                        "shutting down")
                                return
                        }

                        // Close the timeout channel and exit if the block is
                        // above the max height.
                        if uint32(epoch.Height) >= maxHeight {
                                log.Warnf("Waited for %v blocks without "+
                                        "seeing funding transaction confirmed,"+
                                        " cancelling.",
                                        waitBlocksForFundingConf)

                                // Notify the caller of the timeout.
                                close(timeoutChan)
                                return
                        }

                        // TODO: If we are the channel initiator implement
                        // a method for recovering the funds from the funding
                        // transaction

                case <-cancelChan:
                        return

                case <-f.quit:
                        // The fundingManager is shutting down, will resume
                        // waiting for the funding transaction on startup.
                        return
                }
        }
}

// makeLabelForTx updates the label for the confirmed funding transaction. If
// we opened the channel, and lnd's wallet published our funding tx (which is
// not the case for some channels) then we update our transaction label with
// our short channel ID, which is known now that our funding transaction has
// confirmed. We do not label transactions we did not publish, because our
// wallet has no knowledge of them.
func (f *Manager) makeLabelForTx(c *channeldb.OpenChannel) {
        if c.IsInitiator && c.ChanType.HasFundingTx() {
                shortChanID := c.ShortChanID()

                // For zero-conf channels, we'll use the actually-confirmed
                // short channel id.
                if c.IsZeroConf() {
                        shortChanID = c.ZeroConfRealScid()
                }

                label := labels.MakeLabel(
                        labels.LabelTypeChannelOpen, &shortChanID,
                )

                err := f.cfg.UpdateLabel(c.FundingOutpoint.Hash, label)
                if err != nil {
                        log.Errorf("unable to update label: %v", err)
                }
        }
}

// handleFundingConfirmation marks a channel as open in the database, and set
// the channelOpeningState markedOpen. In addition it will report the now
// decided short channel ID to the switch, and close the local discovery signal
// for this channel.
func (f *Manager) handleFundingConfirmation(
        completeChan *channeldb.OpenChannel,
        confChannel *confirmedChannel) error {

        fundingPoint := completeChan.FundingOutpoint
        chanID := lnwire.NewChanIDFromOutPoint(fundingPoint)

        // TODO(roasbeef): ideally persistent state update for chan above
        // should be abstracted

        // Now that that the channel has been fully confirmed, we'll request
        // that the wallet fully verify this channel to ensure that it can be
        // used.
        err := f.cfg.Wallet.ValidateChannel(completeChan, confChannel.fundingTx)
        if err != nil {
                // TODO(roasbeef): delete chan state?
                return fmt.Errorf("unable to validate channel: %w", err)
        }

        // Now that the channel has been validated, we'll persist an alias for
        // this channel if the option-scid-alias feature-bit was negotiated.
        if completeChan.NegotiatedAliasFeature() {
                aliasScid, err := f.cfg.AliasManager.RequestAlias()
                if err != nil {
                        return fmt.Errorf("unable to request alias: %w", err)
                }

                err = f.cfg.AliasManager.AddLocalAlias(
                        aliasScid, confChannel.shortChanID, true, false,
                )
                if err != nil {
                        return fmt.Errorf("unable to request alias: %w", err)
                }
        }

        // The funding transaction now being confirmed, we add this channel to
        // the fundingManager's internal persistent state machine that we use
        // to track the remaining process of the channel opening. This is
        // useful to resume the opening process in case of restarts. We set the
        // opening state before we mark the channel opened in the database,
        // such that we can receover from one of the db writes failing.
        err = f.saveChannelOpeningState(
                &fundingPoint, markedOpen, &confChannel.shortChanID,
        )
        if err != nil {
                return fmt.Errorf("error setting channel state to "+
                        "markedOpen: %v", err)
        }

        // Now that the channel has been fully confirmed and we successfully
        // saved the opening state, we'll mark it as open within the database.
        err = completeChan.MarkAsOpen(confChannel.shortChanID)
        if err != nil {
                return fmt.Errorf("error setting channel pending flag to "+
                        "false:        %v", err)
        }

        // Update the confirmed funding transaction label.
        f.makeLabelForTx(completeChan)

        // Inform the ChannelNotifier that the channel has transitioned from
        // pending open to open.
        f.cfg.NotifyOpenChannelEvent(
                completeChan.FundingOutpoint, completeChan.IdentityPub,
        )

        // Close the discoverySignal channel, indicating to a separate
        // goroutine that the channel now is marked as open in the database
        // and that it is acceptable to process channel_ready messages
        // from the peer.
        if discoverySignal, ok := f.localDiscoverySignals.Load(chanID); ok {
                close(discoverySignal)
        }

        return nil
}

// sendChannelReady creates and sends the channelReady message.
// This should be called after the funding transaction has been confirmed,
// and the channelState is 'markedOpen'.
func (f *Manager) sendChannelReady(completeChan *channeldb.OpenChannel,
        channel *lnwallet.LightningChannel) error {

        chanID := lnwire.NewChanIDFromOutPoint(completeChan.FundingOutpoint)

        var peerKey [33]byte
        copy(peerKey[:], completeChan.IdentityPub.SerializeCompressed())

        // Next, we'll send over the channel_ready message which marks that we
        // consider the channel open by presenting the remote party with our
        // next revocation key. Without the revocation key, the remote party
        // will be unable to propose state transitions.
        nextRevocation, err := channel.NextRevocationKey()
        if err != nil {
                return fmt.Errorf("unable to create next revocation: %w", err)
        }
        channelReadyMsg := lnwire.NewChannelReady(chanID, nextRevocation)

        // If this is a taproot channel, then we also need to send along our
        // set of musig2 nonces as well.
        if completeChan.ChanType.IsTaproot() {
                log.Infof("ChanID(%v): generating musig2 nonces...",
                        chanID)

                f.nonceMtx.Lock()
                localNonce, ok := f.pendingMusigNonces[chanID]
                if !ok {
                        // If we don't have any nonces generated yet for this
                        // first state, then we'll generate them now and stow
                        // them away.  When we receive the funding locked
                        // message, we'll then pass along this same set of
                        // nonces.
                        newNonce, err := channel.GenMusigNonces()
                        if err != nil {
                                f.nonceMtx.Unlock()
                                return err
                        }

                        // Now that we've generated the nonce for this channel,
                        // we'll store it in the set of pending nonces.
                        localNonce = newNonce
                        f.pendingMusigNonces[chanID] = localNonce
                }
                f.nonceMtx.Unlock()

                channelReadyMsg.NextLocalNonce = lnwire.SomeMusig2Nonce(
                        localNonce.PubNonce,
                )
        }

        // If the channel negotiated the option-scid-alias feature bit, we'll
        // send a TLV segment that includes an alias the peer can use in their
        // invoice hop hints. We'll send the first alias we find for the
        // channel since it does not matter which alias we send. We'll error
        // out in the odd case that no aliases are found.
        if completeChan.NegotiatedAliasFeature() {
                aliases := f.cfg.AliasManager.GetAliases(
                        completeChan.ShortChanID(),
                )
                if len(aliases) == 0 {
                        return fmt.Errorf("no aliases found")
                }

                // We can use a pointer to aliases since GetAliases returns a
                // copy of the alias slice.
                channelReadyMsg.AliasScid = &aliases[0]
        }

        // If the peer has disconnected before we reach this point, we will need
        // to wait for him to come back online before sending the channelReady
        // message. This is special for channelReady, since failing to send any
        // of the previous messages in the funding flow just cancels the flow.
        // But now the funding transaction is confirmed, the channel is open
        // and we have to make sure the peer gets the channelReady message when
        // it comes back online. This is also crucial during restart of lnd,
        // where we might try to resend the channelReady message before the
        // server has had the time to connect to the peer. We keep trying to
        // send channelReady until we succeed, or the fundingManager is shut
        // down.
        for {
                peer, err := f.waitForPeerOnline(completeChan.IdentityPub)
                if err != nil {
                        return err
                }

                localAlias := peer.LocalFeatures().HasFeature(
                        lnwire.ScidAliasOptional,
                )
                remoteAlias := peer.RemoteFeatures().HasFeature(
                        lnwire.ScidAliasOptional,
                )

                // We could also refresh the channel state instead of checking
                // whether the feature was negotiated, but this saves us a
                // database read.
                if channelReadyMsg.AliasScid == nil && localAlias &&
                        remoteAlias {

                        // If an alias was not assigned above and the scid
                        // alias feature was negotiated, check if we already
                        // have an alias stored in case handleChannelReady was
                        // called before this. If an alias exists, use that in
                        // channel_ready. Otherwise, request and store an
                        // alias and use that.
                        aliases := f.cfg.AliasManager.GetAliases(
                                completeChan.ShortChannelID,
                        )
                        if len(aliases) == 0 {
                                // No aliases were found.
                                alias, err := f.cfg.AliasManager.RequestAlias()
                                if err != nil {
                                        return err
                                }

                                err = f.cfg.AliasManager.AddLocalAlias(
                                        alias, completeChan.ShortChannelID,
                                        false, false,
                                )
                                if err != nil {
                                        return err
                                }

                                channelReadyMsg.AliasScid = &alias
                        } else {
                                channelReadyMsg.AliasScid = &aliases[0]
                        }
                }

                log.Infof("Peer(%x) is online, sending ChannelReady "+
                        "for ChannelID(%v)", peerKey, chanID)

                if err := peer.SendMessage(true, channelReadyMsg); err == nil {
                        // Sending succeeded, we can break out and continue the
                        // funding flow.
                        break
                }

                log.Warnf("Unable to send channelReady to peer %x: %v. "+
                        "Will retry when online", peerKey, err)
        }

        return nil
}

// receivedChannelReady checks whether or not we've received a ChannelReady
// from the remote peer. If we have, RemoteNextRevocation will be set.
func (f *Manager) receivedChannelReady(node *btcec.PublicKey,
        chanID lnwire.ChannelID) (bool, error) {

        // If the funding manager has exited, return an error to stop looping.
        // Note that the peer may appear as online while the funding manager
        // has stopped due to the shutdown order in the server.
        select {
        case <-f.quit:
                return false, ErrFundingManagerShuttingDown
        default:
        }

        // Avoid a tight loop if peer is offline.
        if _, err := f.waitForPeerOnline(node); err != nil {
                log.Errorf("Wait for peer online failed: %v", err)
                return false, err
        }

        // If we cannot find the channel, then we haven't processed the
        // remote's channelReady message.
        channel, err := f.cfg.FindChannel(node, chanID)
        if err != nil {
                log.Errorf("Unable to locate ChannelID(%v) to determine if "+
                        "ChannelReady was received", chanID)
                return false, err
        }

        // If we haven't insert the next revocation point, we haven't finished
        // processing the channel ready message.
        if channel.RemoteNextRevocation == nil {
                return false, nil
        }

        // Finally, the barrier signal is removed once we finish
        // `handleChannelReady`. If we can still find the signal, we haven't
        // finished processing it yet.
        _, loaded := f.handleChannelReadyBarriers.Load(chanID)

        return !loaded, nil
}

// extractAnnounceParams extracts the various channel announcement and update
// parameters that will be needed to construct a ChannelAnnouncement and a
// ChannelUpdate.
func (f *Manager) extractAnnounceParams(c *channeldb.OpenChannel) (
        lnwire.MilliSatoshi, lnwire.MilliSatoshi) {

        // We'll obtain the min HTLC value we can forward in our direction, as
        // we'll use this value within our ChannelUpdate. This constraint is
        // originally set by the remote node, as it will be the one that will
        // need to determine the smallest HTLC it deems economically relevant.
        fwdMinHTLC := c.LocalChanCfg.MinHTLC

        // We don't necessarily want to go as low as the remote party allows.
        // Check it against our default forwarding policy.
        if fwdMinHTLC < f.cfg.DefaultRoutingPolicy.MinHTLCOut {
                fwdMinHTLC = f.cfg.DefaultRoutingPolicy.MinHTLCOut
        }

        // We'll obtain the max HTLC value we can forward in our direction, as
        // we'll use this value within our ChannelUpdate. This value must be <=
        // channel capacity and <= the maximum in-flight msats set by the peer.
        fwdMaxHTLC := c.LocalChanCfg.MaxPendingAmount
        capacityMSat := lnwire.NewMSatFromSatoshis(c.Capacity)
        if fwdMaxHTLC > capacityMSat {
                fwdMaxHTLC = capacityMSat
        }

        return fwdMinHTLC, fwdMaxHTLC
}

// addToGraph sends a ChannelAnnouncement and a ChannelUpdate to the
// gossiper so that the channel is added to the graph builder's internal graph.
// These announcement messages are NOT broadcasted to the greater network,
// only to the channel counter party. The proofs required to announce the
// channel to the greater network will be created and sent in annAfterSixConfs.
// The peerAlias is used for zero-conf channels to give the counter-party a
// ChannelUpdate they understand. ourPolicy may be set for various
// option-scid-alias channels to re-use the same policy.
func (f *Manager) addToGraph(completeChan *channeldb.OpenChannel,
        shortChanID *lnwire.ShortChannelID,
        peerAlias *lnwire.ShortChannelID,
        ourPolicy *models.ChannelEdgePolicy) error {

        chanID := lnwire.NewChanIDFromOutPoint(completeChan.FundingOutpoint)

        fwdMinHTLC, fwdMaxHTLC := f.extractAnnounceParams(completeChan)

        ann, err := f.newChanAnnouncement(
                f.cfg.IDKey, completeChan.IdentityPub,
                &completeChan.LocalChanCfg.MultiSigKey,
                completeChan.RemoteChanCfg.MultiSigKey.PubKey, *shortChanID,
                chanID, fwdMinHTLC, fwdMaxHTLC, ourPolicy,
                completeChan.ChanType,
        )
        if err != nil {
                return fmt.Errorf("error generating channel "+
                        "announcement: %v", err)
        }

        // Send ChannelAnnouncement and ChannelUpdate to the gossiper to add
        // to the Router's topology.
        errChan := f.cfg.SendAnnouncement(
                ann.chanAnn, discovery.ChannelCapacity(completeChan.Capacity),
                discovery.ChannelPoint(completeChan.FundingOutpoint),
                discovery.TapscriptRoot(completeChan.TapscriptRoot),
        )
        select {
        case err := <-errChan:
                if err != nil {
                        if graph.IsError(err, graph.ErrOutdated,
                                graph.ErrIgnored) {

                                log.Debugf("Graph rejected "+
                                        "ChannelAnnouncement: %v", err)
                        } else {
                                return fmt.Errorf("error sending channel "+
                                        "announcement: %v", err)
                        }
                }
        case <-f.quit:
                return ErrFundingManagerShuttingDown
        }

        errChan = f.cfg.SendAnnouncement(
                ann.chanUpdateAnn, discovery.RemoteAlias(peerAlias),
        )
        select {
        case err := <-errChan:
                if err != nil {
                        if graph.IsError(err, graph.ErrOutdated,
                                graph.ErrIgnored) {

                                log.Debugf("Graph rejected "+
                                        "ChannelUpdate: %v", err)
                        } else {
                                return fmt.Errorf("error sending channel "+
                                        "update: %v", err)
                        }
                }
        case <-f.quit:
                return ErrFundingManagerShuttingDown
        }

        return nil
}

// annAfterSixConfs broadcasts the necessary channel announcement messages to
// the network after 6 confs. Should be called after the channelReady message
// is sent and the channel is added to the graph (channelState is
// 'addedToGraph') and the channel is ready to be used. This is the last
// step in the channel opening process, and the opening state will be deleted
// from the database if successful.
func (f *Manager) annAfterSixConfs(completeChan *channeldb.OpenChannel,
        shortChanID *lnwire.ShortChannelID) error {

        // If this channel is not meant to be announced to the greater network,
        // we'll only send our NodeAnnouncement to our counterparty to ensure we
        // don't leak any of our information.
        announceChan := completeChan.ChannelFlags&lnwire.FFAnnounceChannel != 0
        if !announceChan {
                log.Debugf("Will not announce private channel %v.",
                        shortChanID.ToUint64())

                peer, err := f.waitForPeerOnline(completeChan.IdentityPub)
                if err != nil {
                        return err
                }

                nodeAnn, err := f.cfg.CurrentNodeAnnouncement()
                if err != nil {
                        return fmt.Errorf("unable to retrieve current node "+
                                "announcement: %v", err)
                }

                chanID := lnwire.NewChanIDFromOutPoint(
                        completeChan.FundingOutpoint,
                )
                pubKey := peer.PubKey()
                log.Debugf("Sending our NodeAnnouncement for "+
                        "ChannelID(%v) to %x", chanID, pubKey)

                // TODO(halseth): make reliable. If the peer is not online this
                // will fail, and the opening process will stop. Should instead
                // block here, waiting for the peer to come online.
                if err := peer.SendMessage(true, &nodeAnn); err != nil {
                        return fmt.Errorf("unable to send node announcement "+
                                "to peer %x: %v", pubKey, err)
                }
        } else {
                // Otherwise, we'll wait until the funding transaction has
                // reached 6 confirmations before announcing it.
                numConfs := uint32(completeChan.NumConfsRequired)
                if numConfs < 6 {
                        numConfs = 6
                }
                txid := completeChan.FundingOutpoint.Hash
                log.Debugf("Will announce channel %v after ChannelPoint"+
                        "(%v) has gotten %d confirmations",
                        shortChanID.ToUint64(), completeChan.FundingOutpoint,
                        numConfs)

                fundingScript, err := makeFundingScript(completeChan)
                if err != nil {
                        return fmt.Errorf("unable to create funding script "+
                                "for ChannelPoint(%v): %v",
                                completeChan.FundingOutpoint, err)
                }

                // Register with the ChainNotifier for a notification once the
                // funding transaction reaches at least 6 confirmations.
                confNtfn, err := f.cfg.Notifier.RegisterConfirmationsNtfn(
                        &txid, fundingScript, numConfs,
                        completeChan.BroadcastHeight(),
                )
                if err != nil {
                        return fmt.Errorf("unable to register for "+
                                "confirmation of ChannelPoint(%v): %v",
                                completeChan.FundingOutpoint, err)
                }

                // Wait until 6 confirmations has been reached or the wallet
                // signals a shutdown.
                select {
                case _, ok := <-confNtfn.Confirmed:
                        if !ok {
                                return fmt.Errorf("ChainNotifier shutting "+
                                        "down, cannot complete funding flow "+
                                        "for ChannelPoint(%v)",
                                        completeChan.FundingOutpoint)
                        }
                        // Fallthrough.

                case <-f.quit:
                        return fmt.Errorf("%v, stopping funding flow for "+
                                "ChannelPoint(%v)",
                                ErrFundingManagerShuttingDown,
                                completeChan.FundingOutpoint)
                }

                fundingPoint := completeChan.FundingOutpoint
                chanID := lnwire.NewChanIDFromOutPoint(fundingPoint)

                log.Infof("Announcing ChannelPoint(%v), short_chan_id=%v",
                        &fundingPoint, shortChanID)

                // If this is a non-zero-conf option-scid-alias channel, we'll
                // delete the mappings the gossiper uses so that ChannelUpdates
                // with aliases won't be accepted. This is done elsewhere for
                // zero-conf channels.
                isScidFeature := completeChan.NegotiatedAliasFeature()
                isZeroConf := completeChan.IsZeroConf()
                if isScidFeature && !isZeroConf {
                        baseScid := completeChan.ShortChanID()
                        err := f.cfg.AliasManager.DeleteSixConfs(baseScid)
                        if err != nil {
                                return fmt.Errorf("failed deleting six confs "+
                                        "maps: %v", err)
                        }

                        // We'll delete the edge and add it again via
                        // addToGraph. This is because the peer may have
                        // sent us a ChannelUpdate with an alias and we don't
                        // want to relay this.
                        ourPolicy, err := f.cfg.DeleteAliasEdge(baseScid)
                        if err != nil {
                                return fmt.Errorf("failed deleting real edge "+
                                        "for alias channel from graph: %v",
                                        err)
                        }

                        err = f.addToGraph(
                                completeChan, &baseScid, nil, ourPolicy,
                        )
                        if err != nil {
                                return fmt.Errorf("failed to re-add to "+
                                        "graph: %v", err)
                        }
                }

                // Create and broadcast the proofs required to make this channel
                // public and usable for other nodes for routing.
                err = f.announceChannel(
                        f.cfg.IDKey, completeChan.IdentityPub,
                        &completeChan.LocalChanCfg.MultiSigKey,
                        completeChan.RemoteChanCfg.MultiSigKey.PubKey,
                        *shortChanID, chanID, completeChan.ChanType,
                )
                if err != nil {
                        return fmt.Errorf("channel announcement failed: %w",
                                err)
                }

                log.Debugf("Channel with ChannelPoint(%v), short_chan_id=%v "+
                        "sent to gossiper", &fundingPoint, shortChanID)
        }

        return nil
}

// waitForZeroConfChannel is called when the state is addedToGraph with
// a zero-conf channel. This will wait for the real confirmation, add the
// confirmed SCID to the router graph, and then announce after six confs.
func (f *Manager) waitForZeroConfChannel(c *channeldb.OpenChannel) error {
        // First we'll check whether the channel is confirmed on-chain. If it
        // is already confirmed, the chainntnfs subsystem will return with the
        // confirmed tx. Otherwise, we'll wait here until confirmation occurs.
        confChan, err := f.waitForFundingWithTimeout(c)
        if err != nil {
                return fmt.Errorf("error waiting for zero-conf funding "+
                        "confirmation for ChannelPoint(%v): %v",
                        c.FundingOutpoint, err)
        }

        // We'll need to refresh the channel state so that things are properly
        // populated when validating the channel state. Otherwise, a panic may
        // occur due to inconsistency in the OpenChannel struct.
        err = c.Refresh()
        if err != nil {
                return fmt.Errorf("unable to refresh channel state: %w", err)
        }

        // Now that we have the confirmed transaction and the proper SCID,
        // we'll call ValidateChannel to ensure the confirmed tx is properly
        // formatted.
        err = f.cfg.Wallet.ValidateChannel(c, confChan.fundingTx)
        if err != nil {
                return fmt.Errorf("unable to validate zero-conf channel: "+
                        "%v", err)
        }

        // Once we know the confirmed ShortChannelID, we'll need to save it to
        // the database and refresh the OpenChannel struct with it.
        err = c.MarkRealScid(confChan.shortChanID)
        if err != nil {
                return fmt.Errorf("unable to set confirmed SCID for zero "+
                        "channel: %v", err)
        }

        // Six confirmations have been reached. If this channel is public,
        // we'll delete some of the alias mappings the gossiper uses.
        isPublic := c.ChannelFlags&lnwire.FFAnnounceChannel != 0
        if isPublic {
                err = f.cfg.AliasManager.DeleteSixConfs(c.ShortChannelID)
                if err != nil {
                        return fmt.Errorf("unable to delete base alias after "+
                                "six confirmations: %v", err)
                }

                // TODO: Make this atomic!
                ourPolicy, err := f.cfg.DeleteAliasEdge(c.ShortChanID())
                if err != nil {
                        return fmt.Errorf("unable to delete alias edge from "+
                                "graph: %v", err)
                }

                // We'll need to update the graph with the new ShortChannelID
                // via an addToGraph call. We don't pass in the peer's
                // alias since we'll be using the confirmed SCID from now on
                // regardless if it's public or not.
                err = f.addToGraph(
                        c, &confChan.shortChanID, nil, ourPolicy,
                )
                if err != nil {
                        return fmt.Errorf("failed adding confirmed zero-conf "+
                                "SCID to graph: %v", err)
                }
        }

        // Since we have now marked down the confirmed SCID, we'll also need to
        // tell the Switch to refresh the relevant ChannelLink so that forwards
        // under the confirmed SCID are possible if this is a public channel.
        err = f.cfg.ReportShortChanID(c.FundingOutpoint)
        if err != nil {
                // This should only fail if the link is not found in the
                // Switch's linkIndex map. If this is the case, then the peer
                // has gone offline and the next time the link is loaded, it
                // will have a refreshed state. Just log an error here.
                log.Errorf("unable to report scid for zero-conf channel "+
                        "channel: %v", err)
        }

        // Update the confirmed transaction's label.
        f.makeLabelForTx(c)

        return nil
}

// genFirstStateMusigNonce generates a nonces for the "first" local state. This
// is the verification nonce for the state created for us after the initial
// commitment transaction signed as part of the funding flow.
func genFirstStateMusigNonce(channel *channeldb.OpenChannel,
) (*musig2.Nonces, error) {

        musig2ShaChain, err := channeldb.DeriveMusig2Shachain(
                channel.RevocationProducer,
        )
        if err != nil {
                return nil, fmt.Errorf("unable to generate musig channel "+
                        "nonces: %v", err)
        }

        // We use the _next_ commitment height here as we need to generate the
        // nonce for the next state the remote party will sign for us.
        verNonce, err := channeldb.NewMusigVerificationNonce(
                channel.LocalChanCfg.MultiSigKey.PubKey,
                channel.LocalCommitment.CommitHeight+1,
                musig2ShaChain,
        )
        if err != nil {
                return nil, fmt.Errorf("unable to generate musig channel "+
                        "nonces: %v", err)
        }

        return verNonce, nil
}

// handleChannelReady finalizes the channel funding process and enables the
// channel to enter normal operating mode.
func (f *Manager) handleChannelReady(peer lnpeer.Peer, //nolint:funlen
        msg *lnwire.ChannelReady) {

        defer f.wg.Done()

        // Notify the aux hook that the specified peer just established a
        // channel with us, identified by the given channel ID.
        f.cfg.AuxChannelNegotiator.WhenSome(
                func(acn lnwallet.AuxChannelNegotiator) {
                        acn.ProcessChannelReady(msg.ChanID, peer.PubKey())
                },
        )

        // If we are in development mode, we'll wait for specified duration
        // before processing the channel ready message.
        if f.cfg.Dev != nil {
                duration := f.cfg.Dev.ProcessChannelReadyWait
                log.Warnf("Channel(%v): sleeping %v before processing "+
                        "channel_ready", msg.ChanID, duration)

                select {
                case <-time.After(duration):
                        log.Warnf("Channel(%v): slept %v before processing "+
                                "channel_ready", msg.ChanID, duration)
                case <-f.quit:
                        log.Warnf("Channel(%v): quit sleeping", msg.ChanID)
                        return
                }
        }

        log.Debugf("Received ChannelReady for ChannelID(%v) from "+
                "peer %x", msg.ChanID,
                peer.IdentityKey().SerializeCompressed())

        // We now load or create a new channel barrier for this channel.
        _, loaded := f.handleChannelReadyBarriers.LoadOrStore(
                msg.ChanID, struct{}{},
        )

        // If we are currently in the process of handling a channel_ready
        // message for this channel, ignore.
        if loaded {
                log.Infof("Already handling channelReady for "+
                        "ChannelID(%v), ignoring.", msg.ChanID)
                return
        }

        // If not already handling channelReady for this channel, then the
        // `LoadOrStore` has set up a barrier, and it will be removed once this
        // function exits.
        defer f.handleChannelReadyBarriers.Delete(msg.ChanID)

        localDiscoverySignal, ok := f.localDiscoverySignals.Load(msg.ChanID)
        if ok {
                // Before we proceed with processing the channel_ready
                // message, we'll wait for the local waitForFundingConfirmation
                // goroutine to signal that it has the necessary state in
                // place. Otherwise, we may be missing critical information
                // required to handle forwarded HTLC's.
                select {
                case <-localDiscoverySignal:
                        // Fallthrough
                case <-f.quit:
                        return
                }

                // With the signal received, we can now safely delete the entry
                // from the map.
                f.localDiscoverySignals.Delete(msg.ChanID)
        }

        // First, we'll attempt to locate the channel whose funding workflow is
        // being finalized by this message. We go to the database rather than
        // our reservation map as we may have restarted, mid funding flow. Also
        // provide the node's public key to make the search faster.
        chanID := msg.ChanID
        channel, err := f.cfg.FindChannel(peer.IdentityKey(), chanID)
        if err != nil {
                log.Errorf("Unable to locate ChannelID(%v), cannot complete "+
                        "funding", chanID)
                return
        }

        // If this is a taproot channel, then we can generate the set of nonces
        // the remote party needs to send the next remote commitment here.
        var firstVerNonce *musig2.Nonces
        if channel.ChanType.IsTaproot() {
                firstVerNonce, err = genFirstStateMusigNonce(channel)
                if err != nil {
                        log.Error(err)
                        return
                }
        }

        // We'll need to store the received TLV alias if the option_scid_alias
        // feature was negotiated. This will be used to provide route hints
        // during invoice creation. In the zero-conf case, it is also used to
        // provide a ChannelUpdate to the remote peer. This is done before the
        // call to InsertNextRevocation in case the call to PutPeerAlias fails.
        // If it were to fail on the first call to handleChannelReady, we
        // wouldn't want the channel to be usable yet.
        if channel.NegotiatedAliasFeature() {
                // If the AliasScid field is nil, we must fail out. We will
                // most likely not be able to route through the peer.
                if msg.AliasScid == nil {
                        log.Debugf("Consider closing ChannelID(%v), peer "+
                                "does not implement the option-scid-alias "+
                                "feature properly", chanID)
                        return
                }

                // We'll store the AliasScid so that invoice creation can use
                // it.
                err = f.cfg.AliasManager.PutPeerAlias(chanID, *msg.AliasScid)
                if err != nil {
                        log.Errorf("unable to store peer's alias: %v", err)
                        return
                }

                // If we do not have an alias stored, we'll create one now.
                // This is only used in the upgrade case where a user toggles
                // the option-scid-alias feature-bit to on. We'll also send the
                // channel_ready message here in case the link is created
                // before sendChannelReady is called.
                aliases := f.cfg.AliasManager.GetAliases(
                        channel.ShortChannelID,
                )
                if len(aliases) == 0 {
                        // No aliases were found so we'll request and store an
                        // alias and use it in the channel_ready message.
                        alias, err := f.cfg.AliasManager.RequestAlias()
                        if err != nil {
                                log.Errorf("unable to request alias: %v", err)
                                return
                        }

                        err = f.cfg.AliasManager.AddLocalAlias(
                                alias, channel.ShortChannelID, false, false,
                        )
                        if err != nil {
                                log.Errorf("unable to add local alias: %v",
                                        err)
                                return
                        }

                        secondPoint, err := channel.SecondCommitmentPoint()
                        if err != nil {
                                log.Errorf("unable to fetch second "+
                                        "commitment point: %v", err)
                                return
                        }

                        channelReadyMsg := lnwire.NewChannelReady(
                                chanID, secondPoint,
                        )
                        channelReadyMsg.AliasScid = &alias

                        if firstVerNonce != nil {
                                channelReadyMsg.NextLocalNonce = lnwire.SomeMusig2Nonce( //nolint:ll
                                        firstVerNonce.PubNonce,
                                )
                        }

                        err = peer.SendMessage(true, channelReadyMsg)
                        if err != nil {
                                log.Errorf("unable to send channel_ready: %v",
                                        err)
                                return
                        }
                }
        }

        // If the RemoteNextRevocation is non-nil, it means that we have
        // already processed channelReady for this channel, so ignore. This
        // check is after the alias logic so we store the peer's most recent
        // alias. The spec requires us to validate that subsequent
        // channel_ready messages use the same per commitment point (the
        // second), but it is not actually necessary since we'll just end up
        // ignoring it. We are, however, required to *send* the same per
        // commitment point, since another pedantic implementation might
        // verify it.
        if channel.RemoteNextRevocation != nil {
                log.Infof("Received duplicate channelReady for "+
                        "ChannelID(%v), ignoring.", chanID)
                return
        }

        // If this is a taproot channel, then we'll need to map the received
        // nonces to a nonce pair, and also fetch our pending nonces, which are
        // required in order to make the channel whole.
        var chanOpts []lnwallet.ChannelOpt
        if channel.ChanType.IsTaproot() {
                f.nonceMtx.Lock()
                localNonce, ok := f.pendingMusigNonces[chanID]
                if !ok {
                        // If there's no pending nonce for this channel ID,
                        // we'll use the one generated above.
                        localNonce = firstVerNonce
                        f.pendingMusigNonces[chanID] = firstVerNonce
                }
                f.nonceMtx.Unlock()

                log.Infof("ChanID(%v): applying local+remote musig2 nonces",
                        chanID)

                remoteNonce, err := msg.NextLocalNonce.UnwrapOrErrV(
                        errNoLocalNonce,
                )
                if err != nil {
                        cid := newChanIdentifier(msg.ChanID)
                        f.sendWarning(peer, cid, err)

                        return
                }

                chanOpts = append(
                        chanOpts,
                        lnwallet.WithLocalMusigNonces(localNonce),
                        lnwallet.WithRemoteMusigNonces(&musig2.Nonces{
                                PubNonce: remoteNonce,
                        }),
                )

                // Inform the aux funding controller that the liquidity in the
                // custom channel is now ready to be advertised. We potentially
                // haven't sent our own channel ready message yet, but other
                // than that the channel is ready to count toward available
                // liquidity.
                err = fn.MapOptionZ(
                        f.cfg.AuxFundingController,
                        func(controller AuxFundingController) error {
                                return controller.ChannelReady(
                                        lnwallet.NewAuxChanState(channel),
                                )
                        },
                )
                if err != nil {
                        cid := newChanIdentifier(msg.ChanID)
                        f.sendWarning(peer, cid, err)

                        return
                }
        }

        // The channel_ready message contains the next commitment point we'll
        // need to create the next commitment state for the remote party. So
        // we'll insert that into the channel now before passing it along to
        // other sub-systems.
        err = channel.InsertNextRevocation(msg.NextPerCommitmentPoint)
        if err != nil {
                log.Errorf("unable to insert next commitment point: %v", err)
                return
        }

        // Before we can add the channel to the peer, we'll need to ensure that
        // we have an initial forwarding policy set.
        if err := f.ensureInitialForwardingPolicy(chanID, channel); err != nil {
                log.Errorf("Unable to ensure initial forwarding policy: %v",
                        err)
        }

        err = peer.AddNewChannel(&lnpeer.NewChannel{
                OpenChannel: channel,
                ChanOpts:    chanOpts,
        }, f.quit)
        if err != nil {
                log.Errorf("Unable to add new channel %v with peer %x: %v",
                        channel.FundingOutpoint,
                        peer.IdentityKey().SerializeCompressed(), err,
                )
        }
}

// handleChannelReadyReceived is called once the remote's channelReady message
// is received and processed. At this stage, we must have sent out our
// channelReady message, once the remote's channelReady is processed, the
// channel is now active, thus we change its state to `addedToGraph` to
// let the channel start handling routing.
func (f *Manager) handleChannelReadyReceived(channel *channeldb.OpenChannel,
        scid *lnwire.ShortChannelID, pendingChanID PendingChanID,
        updateChan chan<- *lnrpc.OpenStatusUpdate) error {

        chanID := lnwire.NewChanIDFromOutPoint(channel.FundingOutpoint)

        // Since we've sent+received funding locked at this point, we
        // can clean up the pending musig2 nonce state.
        f.nonceMtx.Lock()
        delete(f.pendingMusigNonces, chanID)
        f.nonceMtx.Unlock()

        var peerAlias *lnwire.ShortChannelID
        if channel.IsZeroConf() {
                // We'll need to wait until channel_ready has been received and
                // the peer lets us know the alias they want to use for the
                // channel. With this information, we can then construct a
                // ChannelUpdate for them.  If an alias does not yet exist,
                // we'll just return, letting the next iteration of the loop
                // check again.
                var defaultAlias lnwire.ShortChannelID
                chanID := lnwire.NewChanIDFromOutPoint(channel.FundingOutpoint)
                foundAlias, _ := f.cfg.AliasManager.GetPeerAlias(chanID)
                if foundAlias == defaultAlias {
                        return nil
                }

                peerAlias = &foundAlias
        }

        err := f.addToGraph(channel, scid, peerAlias, nil)
        if err != nil {
                return fmt.Errorf("failed adding to graph: %w", err)
        }

        // As the channel is now added to the ChannelRouter's topology, the
        // channel is moved to the next state of the state machine. It will be
        // moved to the last state (actually deleted from the database) after
        // the channel is finally announced.
        err = f.saveChannelOpeningState(
                &channel.FundingOutpoint, addedToGraph, scid,
        )
        if err != nil {
                return fmt.Errorf("error setting channel state to"+
                        " addedToGraph: %w", err)
        }

        log.Debugf("Channel(%v) with ShortChanID %v: successfully "+
                "added to graph", chanID, scid)

        err = fn.MapOptionZ(
                f.cfg.AuxFundingController,
                func(controller AuxFundingController) error {
                        return controller.ChannelReady(
                                lnwallet.NewAuxChanState(channel),
                        )
                },
        )
        if err != nil {
                return fmt.Errorf("failed notifying aux funding controller "+
                        "about channel ready: %w", err)
        }

        // Give the caller a final update notifying them that the channel is
        fundingPoint := channel.FundingOutpoint
        cp := &lnrpc.ChannelPoint{
                FundingTxid: &lnrpc.ChannelPoint_FundingTxidBytes{
                        FundingTxidBytes: fundingPoint.Hash[:],
                },
                OutputIndex: fundingPoint.Index,
        }

        if updateChan != nil {
                upd := &lnrpc.OpenStatusUpdate{
                        Update: &lnrpc.OpenStatusUpdate_ChanOpen{
                                ChanOpen: &lnrpc.ChannelOpenUpdate{
                                        ChannelPoint: cp,
                                },
                        },
                        PendingChanId: pendingChanID[:],
                }

                select {
                case updateChan <- upd:
                case <-f.quit:
                        return ErrFundingManagerShuttingDown
                }
        }

        return nil
}

// ensureInitialForwardingPolicy ensures that we have an initial forwarding
// policy set for the given channel. If we don't, we'll fall back to the default
// values.
func (f *Manager) ensureInitialForwardingPolicy(chanID lnwire.ChannelID,
        channel *channeldb.OpenChannel) error {

        // Before we can add the channel to the peer, we'll need to ensure that
        // we have an initial forwarding policy set. This should always be the
        // case except for a channel that was created with lnd <= 0.15.5 and
        // is still pending while updating to this version.
        var needDBUpdate bool
        forwardingPolicy, err := f.getInitialForwardingPolicy(chanID)
        if err != nil {
                log.Errorf("Unable to fetch initial forwarding policy, "+
                        "falling back to default values: %v", err)

                forwardingPolicy = f.defaultForwardingPolicy(
                        channel.LocalChanCfg.ChannelStateBounds,
                )
                needDBUpdate = true
        }

        // We only started storing the actual values for MinHTLCOut and MaxHTLC
        // after 0.16.x, so if a channel was opened with such a version and is
        // still pending while updating to this version, we'll need to set the
        // values to the default values.
        if forwardingPolicy.MinHTLCOut == 0 {
                forwardingPolicy.MinHTLCOut = channel.LocalChanCfg.MinHTLC
                needDBUpdate = true
        }
        if forwardingPolicy.MaxHTLC == 0 {
                forwardingPolicy.MaxHTLC = channel.LocalChanCfg.MaxPendingAmount
                needDBUpdate = true
        }

        // And finally, if we found that the values currently stored aren't
        // sufficient for the link, we'll update the database.
        if needDBUpdate {
                err := f.saveInitialForwardingPolicy(chanID, forwardingPolicy)
                if err != nil {
                        return fmt.Errorf("unable to update initial "+
                                "forwarding policy: %v", err)
                }
        }

        return nil
}

// chanAnnouncement encapsulates the two authenticated announcements that we
// send out to the network after a new channel has been created locally.
type chanAnnouncement struct {
        chanAnn       *lnwire.ChannelAnnouncement1
        chanUpdateAnn *lnwire.ChannelUpdate1
        chanProof     *lnwire.AnnounceSignatures1
}

// newChanAnnouncement creates the authenticated channel announcement messages
// required to broadcast a newly created channel to the network. The
// announcement is two part: the first part authenticates the existence of the
// channel and contains four signatures binding the funding pub keys and
// identity pub keys of both parties to the channel, and the second segment is
// authenticated only by us and contains our directional routing policy for the
// channel. ourPolicy may be set in order to re-use an existing, non-default
// policy.
func (f *Manager) newChanAnnouncement(localPubKey,
        remotePubKey *btcec.PublicKey, localFundingKey *keychain.KeyDescriptor,
        remoteFundingKey *btcec.PublicKey, shortChanID lnwire.ShortChannelID,
        chanID lnwire.ChannelID, fwdMinHTLC, fwdMaxHTLC lnwire.MilliSatoshi,
        ourPolicy *models.ChannelEdgePolicy,
        chanType channeldb.ChannelType) (*chanAnnouncement, error) {

        chainHash := *f.cfg.Wallet.Cfg.NetParams.GenesisHash

        // The unconditional section of the announcement is the ShortChannelID
        // itself which compactly encodes the location of the funding output
        // within the blockchain.
        chanAnn := &lnwire.ChannelAnnouncement1{
                ShortChannelID: shortChanID,
                Features:       lnwire.NewRawFeatureVector(),
                ChainHash:      chainHash,
        }

        // If this is a taproot channel, then we'll set a special bit in the
        // feature vector to indicate to the routing layer that this needs a
        // slightly different type of validation.
        //
        // TODO(roasbeef): temp, remove after gossip 1.5
        if chanType.IsTaproot() {
                log.Debugf("Applying taproot feature bit to "+
                        "ChannelAnnouncement for %v", chanID)

                chanAnn.Features.Set(
                        lnwire.SimpleTaprootChannelsRequiredStaging,
                )
        }

        // The chanFlags field indicates which directed edge of the channel is
        // being updated within the ChannelUpdateAnnouncement announcement
        // below. A value of zero means it's the edge of the "first" node and 1
        // being the other node.
        var chanFlags lnwire.ChanUpdateChanFlags

        // The lexicographical ordering of the two identity public keys of the
        // nodes indicates which of the nodes is "first". If our serialized
        // identity key is lower than theirs then we're the "first" node and
        // second otherwise.
        selfBytes := localPubKey.SerializeCompressed()
        remoteBytes := remotePubKey.SerializeCompressed()
        if bytes.Compare(selfBytes, remoteBytes) == -1 {
                copy(chanAnn.NodeID1[:], localPubKey.SerializeCompressed())
                copy(chanAnn.NodeID2[:], remotePubKey.SerializeCompressed())
                copy(
                        chanAnn.BitcoinKey1[:],
                        localFundingKey.PubKey.SerializeCompressed(),
                )
                copy(
                        chanAnn.BitcoinKey2[:],
                        remoteFundingKey.SerializeCompressed(),
                )

                // If we're the first node then update the chanFlags to
                // indicate the "direction" of the update.
                chanFlags = 0
        } else {
                copy(chanAnn.NodeID1[:], remotePubKey.SerializeCompressed())
                copy(chanAnn.NodeID2[:], localPubKey.SerializeCompressed())
                copy(
                        chanAnn.BitcoinKey1[:],
                        remoteFundingKey.SerializeCompressed(),
                )
                copy(
                        chanAnn.BitcoinKey2[:],
                        localFundingKey.PubKey.SerializeCompressed(),
                )

                // If we're the second node then update the chanFlags to
                // indicate the "direction" of the update.
                chanFlags = 1
        }

        // Our channel update message flags will signal that we support the
        // max_htlc field.
        msgFlags := lnwire.ChanUpdateRequiredMaxHtlc

        // We announce the channel with the default values. Some of
        // these values can later be changed by crafting a new ChannelUpdate.
        chanUpdateAnn := &lnwire.ChannelUpdate1{
                ShortChannelID: shortChanID,
                ChainHash:      chainHash,
                Timestamp:      uint32(time.Now().Unix()),
                MessageFlags:   msgFlags,
                ChannelFlags:   chanFlags,
                TimeLockDelta: uint16(
                        f.cfg.DefaultRoutingPolicy.TimeLockDelta,
                ),
                HtlcMinimumMsat: fwdMinHTLC,
                HtlcMaximumMsat: fwdMaxHTLC,
        }

        // The caller of newChanAnnouncement is expected to provide the initial
        // forwarding policy to be announced. If no persisted initial policy
        // values are found, then we will use the default policy values in the
        // channel announcement.
        storedFwdingPolicy, err := f.getInitialForwardingPolicy(chanID)
        if err != nil && !errors.Is(err, channeldb.ErrChannelNotFound) {
                return nil, fmt.Errorf("unable to generate channel "+
                        "update announcement: %w", err)
        }

        switch {
        case ourPolicy != nil:
                // If ourPolicy is non-nil, modify the default parameters of the
                // ChannelUpdate.
                chanUpdateAnn.MessageFlags = ourPolicy.MessageFlags
                chanUpdateAnn.ChannelFlags = ourPolicy.ChannelFlags
                chanUpdateAnn.TimeLockDelta = ourPolicy.TimeLockDelta
                chanUpdateAnn.HtlcMinimumMsat = ourPolicy.MinHTLC
                chanUpdateAnn.HtlcMaximumMsat = ourPolicy.MaxHTLC
                chanUpdateAnn.BaseFee = uint32(ourPolicy.FeeBaseMSat)
                chanUpdateAnn.FeeRate = uint32(
                        ourPolicy.FeeProportionalMillionths,
                )

        case storedFwdingPolicy != nil:
                chanUpdateAnn.BaseFee = uint32(storedFwdingPolicy.BaseFee)
                chanUpdateAnn.FeeRate = uint32(storedFwdingPolicy.FeeRate)

        default:
                log.Infof("No channel forwarding policy specified for channel "+
                        "announcement of ChannelID(%v). "+
                        "Assuming default fee parameters.", chanID)
                chanUpdateAnn.BaseFee = uint32(
                        f.cfg.DefaultRoutingPolicy.BaseFee,
                )
                chanUpdateAnn.FeeRate = uint32(
                        f.cfg.DefaultRoutingPolicy.FeeRate,
                )
        }

        // With the channel update announcement constructed, we'll generate a
        // signature that signs a double-sha digest of the announcement.
        // This'll serve to authenticate this announcement and any other future
        // updates we may send.
        chanUpdateMsg, err := chanUpdateAnn.DataToSign()
        if err != nil {
                return nil, err
        }
        sig, err := f.cfg.SignMessage(f.cfg.IDKeyLoc, chanUpdateMsg, true)
        if err != nil {
                return nil, fmt.Errorf("unable to generate channel "+
                        "update announcement signature: %w", err)
        }
        chanUpdateAnn.Signature, err = lnwire.NewSigFromSignature(sig)
        if err != nil {
                return nil, fmt.Errorf("unable to generate channel "+
                        "update announcement signature: %w", err)
        }

        // The channel existence proofs itself is currently announced in
        // distinct message. In order to properly authenticate this message, we
        // need two signatures: one under the identity public key used which
        // signs the message itself and another signature of the identity
        // public key under the funding key itself.
        //
        // TODO(roasbeef): use SignAnnouncement here instead?
        chanAnnMsg, err := chanAnn.DataToSign()
        if err != nil {
                return nil, err
        }
        nodeSig, err := f.cfg.SignMessage(f.cfg.IDKeyLoc, chanAnnMsg, true)
        if err != nil {
                return nil, fmt.Errorf("unable to generate node "+
                        "signature for channel announcement: %w", err)
        }
        bitcoinSig, err := f.cfg.SignMessage(
                localFundingKey.KeyLocator, chanAnnMsg, true,
        )
        if err != nil {
                return nil, fmt.Errorf("unable to generate bitcoin "+
                        "signature for node public key: %w", err)
        }

        // Finally, we'll generate the announcement proof which we'll use to
        // provide the other side with the necessary signatures required to
        // allow them to reconstruct the full channel announcement.
        proof := &lnwire.AnnounceSignatures1{
                ChannelID:      chanID,
                ShortChannelID: shortChanID,
        }
        proof.NodeSignature, err = lnwire.NewSigFromSignature(nodeSig)
        if err != nil {
                return nil, err
        }
        proof.BitcoinSignature, err = lnwire.NewSigFromSignature(bitcoinSig)
        if err != nil {
                return nil, err
        }

        return &chanAnnouncement{
                chanAnn:       chanAnn,
                chanUpdateAnn: chanUpdateAnn,
                chanProof:     proof,
        }, nil
}

// announceChannel announces a newly created channel to the rest of the network
// by crafting the two authenticated announcements required for the peers on
// the network to recognize the legitimacy of the channel. The crafted
// announcements are then sent to the channel router to handle broadcasting to
// the network during its next trickle.
// This method is synchronous and will return when all the network requests
// finish, either successfully or with an error.
func (f *Manager) announceChannel(localIDKey, remoteIDKey *btcec.PublicKey,
        localFundingKey *keychain.KeyDescriptor,
        remoteFundingKey *btcec.PublicKey, shortChanID lnwire.ShortChannelID,
        chanID lnwire.ChannelID, chanType channeldb.ChannelType) error {

        // First, we'll create the batch of announcements to be sent upon
        // initial channel creation. This includes the channel announcement
        // itself, the channel update announcement, and our half of the channel
        // proof needed to fully authenticate the channel.
        //
        // We can pass in zeroes for the min and max htlc policy, because we
        // only use the channel announcement message from the returned struct.
        ann, err := f.newChanAnnouncement(
                localIDKey, remoteIDKey, localFundingKey, remoteFundingKey,
                shortChanID, chanID, 0, 0, nil, chanType,
        )
        if err != nil {
                log.Errorf("can't generate channel announcement: %v", err)
                return err
        }

        // We only send the channel proof announcement and the node announcement
        // because addToGraph previously sent the ChannelAnnouncement and
        // the ChannelUpdate announcement messages. The channel proof and node
        // announcements are broadcast to the greater network.
        errChan := f.cfg.SendAnnouncement(ann.chanProof)
        select {
        case err := <-errChan:
                if err != nil {
                        if graph.IsError(err, graph.ErrOutdated,
                                graph.ErrIgnored) {

                                log.Debugf("Graph rejected "+
                                        "AnnounceSignatures: %v", err)
                        } else {
                                log.Errorf("Unable to send channel "+
                                        "proof: %v", err)
                                return err
                        }
                }

        case <-f.quit:
                return ErrFundingManagerShuttingDown
        }

        // Now that the channel is announced to the network, we will also
        // obtain and send a node announcement. This is done since a node
        // announcement is only accepted after a channel is known for that
        // particular node, and this might be our first channel.
        nodeAnn, err := f.cfg.CurrentNodeAnnouncement()
        if err != nil {
                log.Errorf("can't generate node announcement: %v", err)
                return err
        }

        errChan = f.cfg.SendAnnouncement(&nodeAnn)
        select {
        case err := <-errChan:
                if err != nil {
                        if graph.IsError(err, graph.ErrOutdated,
                                graph.ErrIgnored) {

                                log.Debugf("Graph rejected "+
                                        "NodeAnnouncement: %v", err)
                        } else {
                                log.Errorf("Unable to send node "+
                                        "announcement: %v", err)
                                return err
                        }
                }

        case <-f.quit:
                return ErrFundingManagerShuttingDown
        }

        return nil
}

// InitFundingWorkflow sends a message to the funding manager instructing it
// to initiate a single funder workflow with the source peer.
func (f *Manager) InitFundingWorkflow(msg *InitFundingMsg) {
        f.fundingRequests <- msg
}

// getUpfrontShutdownScript takes a user provided script and a getScript
// function which can be used to generate an upfront shutdown script. If our
// peer does not support the feature, this function will error if a non-zero
// script was provided by the user, and return an empty script otherwise. If
// our peer does support the feature, we will return the user provided script
// if non-zero, or a freshly generated script if our node is configured to set
// upfront shutdown scripts automatically.
func getUpfrontShutdownScript(enableUpfrontShutdown bool, peer lnpeer.Peer,
        script lnwire.DeliveryAddress,
        getScript func(bool) (lnwire.DeliveryAddress, error)) (lnwire.DeliveryAddress,
        error) {

        // Check whether the remote peer supports upfront shutdown scripts.
        remoteUpfrontShutdown := peer.RemoteFeatures().HasFeature(
                lnwire.UpfrontShutdownScriptOptional,
        )

        // If the peer does not support upfront shutdown scripts, and one has been
        // provided, return an error because the feature is not supported.
        if !remoteUpfrontShutdown && len(script) != 0 {
                return nil, errUpfrontShutdownScriptNotSupported
        }

        // If the peer does not support upfront shutdown, return an empty address.
        if !remoteUpfrontShutdown {
                return nil, nil
        }

        // If the user has provided an script and the peer supports the feature,
        // return it. Note that user set scripts override the enable upfront
        // shutdown flag.
        if len(script) > 0 {
                return script, nil
        }

        // If we do not have setting of upfront shutdown script enabled, return
        // an empty script.
        if !enableUpfrontShutdown {
                return nil, nil
        }

        // We can safely send a taproot address iff, both sides have negotiated
        // the shutdown-any-segwit feature.
        taprootOK := peer.RemoteFeatures().HasFeature(lnwire.ShutdownAnySegwitOptional) &&
                peer.LocalFeatures().HasFeature(lnwire.ShutdownAnySegwitOptional)

        return getScript(taprootOK)
}

// handleInitFundingMsg creates a channel reservation within the daemon's
// wallet, then sends a funding request to the remote peer kicking off the
// funding workflow.
func (f *Manager) handleInitFundingMsg(msg *InitFundingMsg) {
        var (
                peerKey        = msg.Peer.IdentityKey()
                localAmt       = msg.LocalFundingAmt
                baseFee        = msg.BaseFee
                feeRate        = msg.FeeRate
                minHtlcIn      = msg.MinHtlcIn
                remoteCsvDelay = msg.RemoteCsvDelay
                maxValue       = msg.MaxValueInFlight
                maxHtlcs       = msg.MaxHtlcs
                maxCSV         = msg.MaxLocalCsv
                chanReserve    = msg.RemoteChanReserve
                outpoints      = msg.Outpoints
        )

        // If no maximum CSV delay was set for this channel, we use our default
        // value.
        if maxCSV == 0 {
                maxCSV = f.cfg.MaxLocalCSVDelay
        }

        log.Infof("Initiating fundingRequest(local_amt=%v "+
                "(subtract_fees=%v), push_amt=%v, chain_hash=%v, peer=%x, "+
                "min_confs=%v)", localAmt, msg.SubtractFees, msg.PushAmt,
                msg.ChainHash, peerKey.SerializeCompressed(), msg.MinConfs)

        // We set the channel flags to indicate whether we want this channel to
        // be announced to the network.
        var channelFlags lnwire.FundingFlag
        if !msg.Private {
                // This channel will be announced.
                channelFlags = lnwire.FFAnnounceChannel
        }

        // If the caller specified their own channel ID, then we'll use that.
        // Otherwise we'll generate a fresh one as normal.  This will be used
        // to track this reservation throughout its lifetime.
        var chanID PendingChanID
        if msg.PendingChanID == zeroID {
                chanID = f.nextPendingChanID()
        } else {
                // If the user specified their own pending channel ID, then
                // we'll ensure it doesn't collide with any existing pending
                // channel ID.
                chanID = msg.PendingChanID
                if _, err := f.getReservationCtx(peerKey, chanID); err == nil {
                        msg.Err <- fmt.Errorf("pendingChannelID(%x) "+
                                "already present", chanID[:])
                        return
                }
        }

        // Check whether the peer supports upfront shutdown, and get an address
        // which should be used (either a user specified address or a new
        // address from the wallet if our node is configured to set shutdown
        // address by default).
        shutdown, err := getUpfrontShutdownScript(
                f.cfg.EnableUpfrontShutdown, msg.Peer, msg.ShutdownScript,
                f.selectShutdownScript,
        )
        if err != nil {
                msg.Err <- err
                return
        }

        // Initialize a funding reservation with the local wallet. If the
        // wallet doesn't have enough funds to commit to this channel, then the
        // request will fail, and be aborted.
        //
        // Before we init the channel, we'll also check to see what commitment
        // format we can use with this peer. This is dependent on *both* us and
        // the remote peer are signaling the proper feature bit.
        chanType, commitType, err := negotiateCommitmentType(
                msg.ChannelType, msg.Peer.LocalFeatures(),
                msg.Peer.RemoteFeatures(),
        )
        if err != nil {
                log.Errorf("channel type negotiation failed: %v", err)
                msg.Err <- err
                return
        }

        var (
                zeroConf bool
                scid     bool
        )

        if chanType != nil {
                // Check if the returned chanType includes either the zero-conf
                // or scid-alias bits.
                featureVec := lnwire.RawFeatureVector(*chanType)
                zeroConf = featureVec.IsSet(lnwire.ZeroConfRequired)
                scid = featureVec.IsSet(lnwire.ScidAliasRequired)

                // The option-scid-alias channel type for a public channel is
                // disallowed.
                if scid && !msg.Private {
                        err = fmt.Errorf("option-scid-alias chantype for " +
                                "public channel")
                        log.Error(err)
                        msg.Err <- err

                        return
                }
        }

        // First, we'll query the fee estimator for a fee that should get the
        // commitment transaction confirmed by the next few blocks (conf target
        // of 3). We target the near blocks here to ensure that we'll be able
        // to execute a timely unilateral channel closure if needed.
        commitFeePerKw, err := f.cfg.FeeEstimator.EstimateFeePerKW(3)
        if err != nil {
                msg.Err <- err
                return
        }

        // For anchor channels cap the initial commit fee rate at our defined
        // maximum.
        if commitType.HasAnchors() &&
                commitFeePerKw > f.cfg.MaxAnchorsCommitFeeRate {

                commitFeePerKw = f.cfg.MaxAnchorsCommitFeeRate
        }

        var scidFeatureVal bool
        if hasFeatures(
                msg.Peer.LocalFeatures(), msg.Peer.RemoteFeatures(),
                lnwire.ScidAliasOptional,
        ) {

                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 := fn.MapOptionZ(
                f.cfg.AuxFundingController,
                func(c AuxFundingController) AuxTapscriptResult {
                        return c.DeriveTapscriptRoot(chanID)
                },
        ).Unpack()
        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,
                NodeID:            peerKey,
                NodeAddr:          msg.Peer.Address(),
                SubtractFees:      msg.SubtractFees,
                LocalFundingAmt:   localAmt,
                RemoteFundingAmt:  0,
                FundUpToMaxAmt:    msg.FundUpToMaxAmt,
                MinFundAmt:        msg.MinFundAmt,
                RemoteChanReserve: chanReserve,
                Outpoints:         outpoints,
                CommitFeePerKw:    commitFeePerKw,
                FundingFeePerKw:   msg.FundingFeePerKw,
                PushMSat:          msg.PushAmt,
                Flags:             channelFlags,
                MinConfs:          msg.MinConfs,
                CommitType:        commitType,
                ChanFunder:        msg.ChanFunder,
                // Unconfirmed Utxos which are marked by the sweeper subsystem
                // are excluded from the coin selection because they are not
                // final and can be RBFed by the sweeper subsystem.
                AllowUtxoForFunding: func(u lnwallet.Utxo) bool {
                        // Utxos with at least 1 confirmation are safe to use
                        // for channel openings because they don't bare the risk
                        // of being replaced (BIP 125 RBF).
                        if u.Confirmations > 0 {
                                return true
                        }

                        // Query the sweeper storage to make sure we don't use
                        // an unconfirmed utxo still in use by the sweeper
                        // subsystem.
                        return !f.cfg.IsSweeperOutpoint(u.OutPoint)
                },
                ZeroConf:         zeroConf,
                OptionScidAlias:  scid,
                ScidAliasFeature: scidFeatureVal,
                Memo:             msg.Memo,
                TapscriptRoot:    tapscriptRoot,
        }

        reservation, err := f.cfg.Wallet.InitChannelReservation(req)
        if err != nil {
                msg.Err <- err
                return
        }

        if zeroConf {
                // Store the alias for zero-conf channels in the underlying
                // partial channel state.
                aliasScid, err := f.cfg.AliasManager.RequestAlias()
                if err != nil {
                        msg.Err <- err
                        return
                }

                reservation.AddAlias(aliasScid)
        }

        // Set our upfront shutdown address in the existing reservation.
        reservation.SetOurUpfrontShutdown(shutdown)

        // Now that we have successfully reserved funds for this channel in the
        // wallet, we can fetch the final channel capacity. This is done at
        // this point since the final capacity might change in case of
        // SubtractFees=true.
        capacity := reservation.Capacity()

        log.Infof("Target commit tx sat/kw for pendingID(%x): %v", chanID,
                int64(commitFeePerKw))

        // If the remote CSV delay was not set in the open channel request,
        // we'll use the RequiredRemoteDelay closure to compute the delay we
        // require given the total amount of funds within the channel.
        if remoteCsvDelay == 0 {
                remoteCsvDelay = f.cfg.RequiredRemoteDelay(capacity)
        }

        // If no minimum HTLC value was specified, use the default one.
        if minHtlcIn == 0 {
                minHtlcIn = f.cfg.DefaultMinHtlcIn
        }

        // If no max value was specified, use the default one.
        if maxValue == 0 {
                maxValue = f.cfg.RequiredRemoteMaxValue(capacity)
        }

        if maxHtlcs == 0 {
                maxHtlcs = f.cfg.RequiredRemoteMaxHTLCs(capacity)
        }

        // Once the reservation has been created, and indexed, queue a funding
        // request to the remote peer, kicking off the funding workflow.
        ourContribution := reservation.OurContribution()

        // Prepare the optional channel fee values from the initFundingMsg. If
        // useBaseFee or useFeeRate are false the client did not provide fee
        // values hence we assume default fee settings from the config.
        forwardingPolicy := f.defaultForwardingPolicy(
                ourContribution.ChannelStateBounds,
        )
        if baseFee != nil {
                forwardingPolicy.BaseFee = lnwire.MilliSatoshi(*baseFee)
        }

        if feeRate != nil {
                forwardingPolicy.FeeRate = lnwire.MilliSatoshi(*feeRate)
        }

        // Fetch our dust limit which is part of the default channel
        // constraints, and log it.
        ourDustLimit := ourContribution.DustLimit

        log.Infof("Dust limit for pendingID(%x): %v", chanID, ourDustLimit)

        // If the channel reserve is not specified, then we calculate an
        // appropriate amount here.
        if chanReserve == 0 {
                chanReserve = f.cfg.RequiredRemoteChanReserve(
                        capacity, ourDustLimit,
                )
        }

        // If a pending channel map for this peer isn't already created, then
        // we create one, ultimately allowing us to track this pending
        // reservation within the target peer.
        peerIDKey := newSerializedKey(peerKey)
        f.resMtx.Lock()
        if _, ok := f.activeReservations[peerIDKey]; !ok {
                f.activeReservations[peerIDKey] = make(pendingChannels)
        }

        resCtx := &reservationWithCtx{
                chanAmt:           capacity,
                forwardingPolicy:  *forwardingPolicy,
                remoteCsvDelay:    remoteCsvDelay,
                remoteMinHtlc:     minHtlcIn,
                remoteMaxValue:    maxValue,
                remoteMaxHtlcs:    maxHtlcs,
                remoteChanReserve: chanReserve,
                maxLocalCsv:       maxCSV,
                channelType:       chanType,
                reservation:       reservation,
                peer:              msg.Peer,
                updates:           msg.Updates,
                err:               msg.Err,
        }
        f.activeReservations[peerIDKey][chanID] = resCtx
        f.resMtx.Unlock()

        // Update the timestamp once the InitFundingMsg has been handled.
        defer resCtx.updateTimestamp()

        // Check the sanity of the selected channel constraints.
        bounds := &channeldb.ChannelStateBounds{
                ChanReserve:      chanReserve,
                MaxPendingAmount: maxValue,
                MinHTLC:          minHtlcIn,
                MaxAcceptedHtlcs: maxHtlcs,
        }
        commitParams := &channeldb.CommitmentParams{
                DustLimit: ourDustLimit,
                CsvDelay:  remoteCsvDelay,
        }
        err = lnwallet.VerifyConstraints(
                bounds, commitParams, resCtx.maxLocalCsv, capacity,
        )
        if err != nil {
                _, reserveErr := f.cancelReservationCtx(peerKey, chanID, false)
                if reserveErr != nil {
                        log.Errorf("unable to cancel reservation: %v",
                                reserveErr)
                }

                msg.Err <- err
                return
        }

        // When opening a script enforced channel lease, include the required
        // expiry TLV record in our proposal.
        var leaseExpiry *lnwire.LeaseExpiry
        if commitType == lnwallet.CommitmentTypeScriptEnforcedLease {
                leaseExpiry = new(lnwire.LeaseExpiry)
                *leaseExpiry = lnwire.LeaseExpiry(reservation.LeaseExpiry())
        }

        log.Infof("Starting funding workflow with %v for pending_id(%x), "+
                "committype=%v", msg.Peer.Address(), chanID, commitType)

        reservation.SetState(lnwallet.SentOpenChannel)

        fundingOpen := lnwire.OpenChannel{
                ChainHash:             *f.cfg.Wallet.Cfg.NetParams.GenesisHash,
                PendingChannelID:      chanID,
                FundingAmount:         capacity,
                PushAmount:            msg.PushAmt,
                DustLimit:             ourDustLimit,
                MaxValueInFlight:      maxValue,
                ChannelReserve:        chanReserve,
                HtlcMinimum:           minHtlcIn,
                FeePerKiloWeight:      uint32(commitFeePerKw),
                CsvDelay:              remoteCsvDelay,
                MaxAcceptedHTLCs:      maxHtlcs,
                FundingKey:            ourContribution.MultiSigKey.PubKey,
                RevocationPoint:       ourContribution.RevocationBasePoint.PubKey,
                PaymentPoint:          ourContribution.PaymentBasePoint.PubKey,
                HtlcPoint:             ourContribution.HtlcBasePoint.PubKey,
                DelayedPaymentPoint:   ourContribution.DelayBasePoint.PubKey,
                FirstCommitmentPoint:  ourContribution.FirstCommitmentPoint,
                ChannelFlags:          channelFlags,
                UpfrontShutdownScript: shutdown,
                ChannelType:           chanType,
                LeaseExpiry:           leaseExpiry,
        }

        if commitType.IsTaproot() {
                fundingOpen.LocalNonce = lnwire.SomeMusig2Nonce(
                        ourContribution.LocalNonce.PubNonce,
                )
        }

        if err := msg.Peer.SendMessage(true, &fundingOpen); err != nil {
                e := fmt.Errorf("unable to send funding request message: %w",
                        err)
                log.Errorf(e.Error())

                // Since we were unable to send the initial message to the peer
                // and start the funding flow, we'll cancel this reservation.
                _, err := f.cancelReservationCtx(peerKey, chanID, false)
                if err != nil {
                        log.Errorf("unable to cancel reservation: %v", err)
                }

                msg.Err <- e
                return
        }
}

// handleWarningMsg processes the warning which was received from remote peer.
func (f *Manager) handleWarningMsg(peer lnpeer.Peer, msg *lnwire.Warning) {
        log.Warnf("received warning message from peer %x: %v",
                peer.IdentityKey().SerializeCompressed(), msg.Warning())
}

// handleErrorMsg processes the error which was received from remote peer,
// depending on the type of error we should do different clean up steps and
// inform the user about it.
func (f *Manager) handleErrorMsg(peer lnpeer.Peer, msg *lnwire.Error) {
        chanID := msg.ChanID
        peerKey := peer.IdentityKey()

        // First, we'll attempt to retrieve and cancel the funding workflow
        // that this error was tied to. If we're unable to do so, then we'll
        // exit early as this was an unwarranted error.
        resCtx, err := f.cancelReservationCtx(peerKey, chanID, true)
        if err != nil {
                log.Warnf("Received error for non-existent funding "+
                        "flow: %v (%v)", err, msg.Error())
                return
        }

        // If we did indeed find the funding workflow, then we'll return the
        // error back to the caller (if any), and cancel the workflow itself.
        fundingErr := fmt.Errorf("received funding error from %x: %v",
                peerKey.SerializeCompressed(), msg.Error(),
        )
        log.Errorf(fundingErr.Error())

        // If this was a PSBT funding flow, the remote likely timed out because
        // we waited too long. Return a nice error message to the user in that
        // case so the user knows what's the problem.
        if resCtx.reservation.IsPsbt() {
                fundingErr = fmt.Errorf("%w: %v", chanfunding.ErrRemoteCanceled,
                        fundingErr)
        }

        resCtx.err <- fundingErr
}

// pruneZombieReservations loops through all pending reservations and fails the
// funding flow for any reservations that have not been updated since the
// ReservationTimeout and are not locked waiting for the funding transaction.
func (f *Manager) pruneZombieReservations() {
        zombieReservations := make(pendingChannels)

        f.resMtx.RLock()
        for _, pendingReservations := range f.activeReservations {
                for pendingChanID, resCtx := range pendingReservations {
                        if resCtx.isLocked() {
                                continue
                        }

                        // We don't want to expire PSBT funding reservations.
                        // These reservations are always initiated by us and the
                        // remote peer is likely going to cancel them after some
                        // idle time anyway. So no need for us to also prune
                        // them.
                        sinceLastUpdate := time.Since(resCtx.lastUpdated)
                        isExpired := sinceLastUpdate > f.cfg.ReservationTimeout
                        if !resCtx.reservation.IsPsbt() && isExpired {
                                zombieReservations[pendingChanID] = resCtx
                        }
                }
        }
        f.resMtx.RUnlock()

        for pendingChanID, resCtx := range zombieReservations {
                err := fmt.Errorf("reservation timed out waiting for peer "+
                        "(peer_id:%x, chan_id:%x)",
                        resCtx.peer.IdentityKey().SerializeCompressed(),
                        pendingChanID[:])
                log.Warnf(err.Error())

                chanID := lnwire.NewChanIDFromOutPoint(
                        *resCtx.reservation.FundingOutpoint(),
                )

                // Create channel identifier and set the channel ID.
                cid := newChanIdentifier(pendingChanID)
                cid.setChanID(chanID)

                f.failFundingFlow(resCtx.peer, cid, err)
        }
}

// cancelReservationCtx does all needed work in order to securely cancel the
// reservation.
func (f *Manager) cancelReservationCtx(peerKey *btcec.PublicKey,
        pendingChanID PendingChanID,
        byRemote bool) (*reservationWithCtx, error) {

        log.Infof("Cancelling funding reservation for node_key=%x, "+
                "chan_id=%x", peerKey.SerializeCompressed(), pendingChanID[:])

        peerIDKey := newSerializedKey(peerKey)
        f.resMtx.Lock()
        defer f.resMtx.Unlock()

        nodeReservations, ok := f.activeReservations[peerIDKey]
        if !ok {
                // No reservations for this node.
                return nil, fmt.Errorf("no active reservations for peer(%x)",
                        peerIDKey[:])
        }

        ctx, ok := nodeReservations[pendingChanID]
        if !ok {
                return nil, fmt.Errorf("unknown channel (id: %x) for "+
                        "peer(%x)", pendingChanID[:], peerIDKey[:])
        }

        // If the reservation was a PSBT funding flow and it was canceled by the
        // remote peer, then we need to thread through a different error message
        // to the subroutine that's waiting for the user input so it can return
        // a nice error message to the user.
        if ctx.reservation.IsPsbt() && byRemote {
                ctx.reservation.RemoteCanceled()
        }

        if err := ctx.reservation.Cancel(); err != nil {
                return nil, fmt.Errorf("unable to cancel reservation: %w", err)
        }

        delete(nodeReservations, pendingChanID)

        // If this was the last active reservation for this peer, delete the
        // peer's entry altogether.
        if len(nodeReservations) == 0 {
                delete(f.activeReservations, peerIDKey)
        }
        return ctx, nil
}

// deleteReservationCtx deletes the reservation uniquely identified by the
// target public key of the peer, and the specified pending channel ID.
func (f *Manager) deleteReservationCtx(peerKey *btcec.PublicKey,
        pendingChanID PendingChanID) {

        peerIDKey := newSerializedKey(peerKey)
        f.resMtx.Lock()
        defer f.resMtx.Unlock()

        nodeReservations, ok := f.activeReservations[peerIDKey]
        if !ok {
                // No reservations for this node.
                return
        }
        delete(nodeReservations, pendingChanID)

        // If this was the last active reservation for this peer, delete the
        // peer's entry altogether.
        if len(nodeReservations) == 0 {
                delete(f.activeReservations, peerIDKey)
        }
}

// getReservationCtx returns the reservation context for a particular pending
// channel ID for a target peer.
func (f *Manager) getReservationCtx(peerKey *btcec.PublicKey,
        pendingChanID PendingChanID) (*reservationWithCtx, error) {

        peerIDKey := newSerializedKey(peerKey)
        f.resMtx.RLock()
        resCtx, ok := f.activeReservations[peerIDKey][pendingChanID]
        f.resMtx.RUnlock()

        if !ok {
                return nil, fmt.Errorf("unknown channel (id: %x) for "+
                        "peer(%x)", pendingChanID[:], peerIDKey[:])
        }

        return resCtx, nil
}

// IsPendingChannel returns a boolean indicating whether the channel identified
// by the pendingChanID and given peer is pending, meaning it is in the process
// of being funded. After the funding transaction has been confirmed, the
// channel will receive a new, permanent channel ID, and will no longer be
// considered pending.
func (f *Manager) IsPendingChannel(pendingChanID PendingChanID,
        peer lnpeer.Peer) bool {

        peerIDKey := newSerializedKey(peer.IdentityKey())
        f.resMtx.RLock()
        _, ok := f.activeReservations[peerIDKey][pendingChanID]
        f.resMtx.RUnlock()

        return ok
}

func copyPubKey(pub *btcec.PublicKey) *btcec.PublicKey {
        var tmp btcec.JacobianPoint
        pub.AsJacobian(&tmp)
        tmp.ToAffine()
        return btcec.NewPublicKey(&tmp.X, &tmp.Y)
}

// defaultForwardingPolicy returns the default forwarding policy based on the
// default routing policy and our local channel constraints.
func (f *Manager) defaultForwardingPolicy(
        bounds channeldb.ChannelStateBounds) *models.ForwardingPolicy {

        return &models.ForwardingPolicy{
                MinHTLCOut:    bounds.MinHTLC,
                MaxHTLC:       bounds.MaxPendingAmount,
                BaseFee:       f.cfg.DefaultRoutingPolicy.BaseFee,
                FeeRate:       f.cfg.DefaultRoutingPolicy.FeeRate,
                TimeLockDelta: f.cfg.DefaultRoutingPolicy.TimeLockDelta,
        }
}

// saveInitialForwardingPolicy saves the forwarding policy for the provided
// chanPoint in the channelOpeningStateBucket.
func (f *Manager) saveInitialForwardingPolicy(chanID lnwire.ChannelID,
        forwardingPolicy *models.ForwardingPolicy) error {

        return f.cfg.ChannelDB.SaveInitialForwardingPolicy(
                chanID, forwardingPolicy,
        )
}

// getInitialForwardingPolicy fetches the initial forwarding policy for a given
// channel id from the database which will be applied during the channel
// announcement phase.
func (f *Manager) getInitialForwardingPolicy(
        chanID lnwire.ChannelID) (*models.ForwardingPolicy, error) {

        return f.cfg.ChannelDB.GetInitialForwardingPolicy(chanID)
}

// deleteInitialForwardingPolicy removes channel fees for this chanID from
// the database.
func (f *Manager) deleteInitialForwardingPolicy(chanID lnwire.ChannelID) error {
        return f.cfg.ChannelDB.DeleteInitialForwardingPolicy(chanID)
}

// saveChannelOpeningState saves the channelOpeningState for the provided
// chanPoint to the channelOpeningStateBucket.
func (f *Manager) saveChannelOpeningState(chanPoint *wire.OutPoint,
        state channelOpeningState, shortChanID *lnwire.ShortChannelID) error {

        var outpointBytes bytes.Buffer
        if err := WriteOutpoint(&outpointBytes, chanPoint); err != nil {
                return err
        }

        // Save state and the uint64 representation of the shortChanID
        // for later use.
        scratch := make([]byte, 10)
        byteOrder.PutUint16(scratch[:2], uint16(state))
        byteOrder.PutUint64(scratch[2:], shortChanID.ToUint64())

        return f.cfg.ChannelDB.SaveChannelOpeningState(
                outpointBytes.Bytes(), scratch,
        )
}

// getChannelOpeningState fetches the channelOpeningState for the provided
// chanPoint from the database, or returns ErrChannelNotFound if the channel
// is not found.
func (f *Manager) getChannelOpeningState(chanPoint *wire.OutPoint) (
        channelOpeningState, *lnwire.ShortChannelID, error) {

        var outpointBytes bytes.Buffer
        if err := WriteOutpoint(&outpointBytes, chanPoint); err != nil {
                return 0, nil, err
        }

        value, err := f.cfg.ChannelDB.GetChannelOpeningState(
                outpointBytes.Bytes(),
        )
        if err != nil {
                return 0, nil, err
        }

        state := channelOpeningState(byteOrder.Uint16(value[:2]))
        shortChanID := lnwire.NewShortChanIDFromInt(byteOrder.Uint64(value[2:]))
        return state, &shortChanID, nil
}

// deleteChannelOpeningState removes any state for chanPoint from the database.
func (f *Manager) deleteChannelOpeningState(chanPoint *wire.OutPoint) error {
        var outpointBytes bytes.Buffer
        if err := WriteOutpoint(&outpointBytes, chanPoint); err != nil {
                return err
        }

        return f.cfg.ChannelDB.DeleteChannelOpeningState(
                outpointBytes.Bytes(),
        )
}

// selectShutdownScript selects the shutdown script we should send to the peer.
// If we can use taproot, then we prefer that, otherwise we'll use a p2wkh
// script.
func (f *Manager) selectShutdownScript(taprootOK bool,
) (lnwire.DeliveryAddress, error) {

        addrType := lnwallet.WitnessPubKey
        if taprootOK {
                addrType = lnwallet.TaprootPubkey
        }

        addr, err := f.cfg.Wallet.NewAddress(
                addrType, false, lnwallet.DefaultAccountName,
        )
        if err != nil {
                return nil, err
        }

        return txscript.PayToAddrScript(addr)
}

// waitForPeerOnline blocks until the peer specified by peerPubkey comes online
// and then returns the online peer.
func (f *Manager) waitForPeerOnline(peerPubkey *btcec.PublicKey) (lnpeer.Peer,
        error) {

        peerChan := make(chan lnpeer.Peer, 1)

        var peerKey [33]byte
        copy(peerKey[:], peerPubkey.SerializeCompressed())

        f.cfg.NotifyWhenOnline(peerKey, peerChan)

        var peer lnpeer.Peer
        select {
        case peer = <-peerChan:
        case <-f.quit:
                return peer, ErrFundingManagerShuttingDown
        }
        return peer, nil
}

lightningnetwork / lnd / 18016273007

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