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fundingmanager.go
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fundingmanager.go
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package main
import (
"bytes"
"encoding/binary"
"fmt"
"sync"
"sync/atomic"
"time"
"golang.org/x/crypto/salsa20"
"github.com/boltdb/bolt"
"github.com/davecgh/go-spew/spew"
"github.com/go-errors/errors"
"github.com/lightningnetwork/lnd/chainntnfs"
"github.com/lightningnetwork/lnd/channeldb"
"github.com/lightningnetwork/lnd/htlcswitch"
"github.com/lightningnetwork/lnd/lnrpc"
"github.com/lightningnetwork/lnd/lnwallet"
"github.com/lightningnetwork/lnd/lnwire"
"github.com/roasbeef/btcd/btcec"
"github.com/roasbeef/btcd/chaincfg/chainhash"
"github.com/roasbeef/btcd/wire"
"github.com/roasbeef/btcutil"
"google.golang.org/grpc"
)
const (
// TODO(roasbeef): tune
msgBufferSize = 50
defaultCsvDelay = 4
// maxFundingAmount is a soft-limit of the maximum channel size
// accepted within the Lightning Protocol Currently. This limit is
// currently defined in BOLT-0002, and serves as an initial
// precaturioary limit while implementations are battle tested in the
// real world.
//
// TODO(roasbeef): add command line param to modify
maxFundingAmount = btcutil.Amount(1 << 24)
// maxWaitNumBlocksFundingConf is the maximum number of blocks to wait
// for the funding transaction to be confirmed before forgetting about
// the channel. 288 blocks is ~48 hrs
maxWaitNumBlocksFundingConf = 288
)
// 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
peerAddress *lnwire.NetAddress
chanAmt btcutil.Amount
updates chan *lnrpc.OpenStatusUpdate
err chan error
}
// 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 {
peerAddress *lnwire.NetAddress
*openChanReq
}
// fundingOpenMsg couples an lnwire.OpenChannel message with the peer who sent
// the message. This allows the funding manager to queue a response directly to
// the peer, progressing the funding workflow.
type fundingOpenMsg struct {
msg *lnwire.OpenChannel
peerAddress *lnwire.NetAddress
}
// fundingAcceptMsg couples an lnwire.AcceptChannel message with the peer who
// sent the message. This allows the funding manager to queue a response
// directly to the peer, progressing the funding workflow.
type fundingAcceptMsg struct {
msg *lnwire.AcceptChannel
peerAddress *lnwire.NetAddress
}
// fundingCreatedMsg couples an lnwire.FundingCreated message with the peer who
// sent the message. This allows the funding manager to queue a response
// directly to the peer, progressing the funding workflow.
type fundingCreatedMsg struct {
msg *lnwire.FundingCreated
peerAddress *lnwire.NetAddress
}
// fundingSignedMsg couples an lnwire.FundingSigned message with the peer who
// sent the message. This allows the funding manager to queue a response
// directly to the peer, progressing the funding workflow.
type fundingSignedMsg struct {
msg *lnwire.FundingSigned
peerAddress *lnwire.NetAddress
}
// fundingLockedMsg couples an lnwire.FundingLocked message with the peer who
// sent the message. This allows the funding manager to finalize the funding
// process and announce the existence of the new channel.
type fundingLockedMsg struct {
msg *lnwire.FundingLocked
peerAddress *lnwire.NetAddress
}
// fundingErrorMsg couples an lnwire.Error message with the peer who sent the
// message. This allows the funding manager to properly process the error.
type fundingErrorMsg struct {
err *lnwire.Error
peerAddress *lnwire.NetAddress
}
// 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[[32]byte]*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
}
// fundingConfig defines the configuration for the FundingManager. All elements
// within the configuration MUST be non-nil for the FundingManager to carry out
// its duties.
type fundingConfig struct {
// IDKey is the PublicKey that is used to identify this node within the
// Lightning Network.
IDKey *btcec.PublicKey
// Wallet handles the parts of the funding process that involves moving
// funds from on-chain transaction outputs into Lightning channels.
Wallet *lnwallet.LightningWallet
// FeeEstimator calculates appropriate fee rates based on historical
// transaction information.
FeeEstimator lnwallet.FeeEstimator
// ArbiterChan allows the FundingManager to notify the BreachArbiter
// that a new channel has been created that should be observed to
// ensure that the channel counterparty hasn't broadcast an invalid
// commitment transaction.
ArbiterChan chan<- *lnwallet.LightningChannel
// 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
// SignMessage signs an arbitrary method 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(pubKey *btcec.PublicKey, msg []byte) (*btcec.Signature, error)
// CurrentNodeAnnouncement should return the latest, fully signed node
// announcement from the backing Lighting Network node.
CurrentNodeAnnouncement func() (lnwire.NodeAnnouncement, error)
// SendAnnouncement is used by the FundingManager to announce newly
// created channels to the rest of the Lightning Network.
SendAnnouncement func(msg lnwire.Message) error
// SendToPeer allows the FundingManager to send messages to the peer
// node during the multiple steps involved in the creation of the
// channel's funding transaction and initial commitment transaction.
SendToPeer func(target *btcec.PublicKey, msgs ...lnwire.Message) 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 fundingLocked message, since it MUST be
// delivered after the funding transaction is confirmed.
NotifyWhenOnline func(peer *btcec.PublicKey, connectedChan chan<- struct{})
// FindPeer searches the list of peers connected to the node so that
// the FundingManager can notify other daemon subsystems as necessary
// during the funding process.
FindPeer func(peerKey *btcec.PublicKey) (*peer, error)
// FindChannel queries the database for the channel with the given
// channel ID.
FindChannel func(chanID lnwire.ChannelID) (*lnwallet.LightningChannel, 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 htlcswitch.ForwardingPolicy
// 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
}
// fundingManager 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 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 fundingManager struct {
// MUST be used atomically.
started int32
stopped int32
// cfg is a copy of the configuration struct that the FundingManager was
// initialized with.
cfg *fundingConfig
// 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.
nonceMtx sync.RWMutex
chanIDNonce uint64
// 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][32]byte
// resMtx guards both of the maps above to ensure that all access is
// goroutine stafe.
resMtx sync.RWMutex
// fundingMsgs is a channel which receives wrapped wire messages
// related to funding workflow from outside peers.
fundingMsgs chan interface{}
// queries is a channel which receives requests to query the internal
// state of the funding manager.
queries chan interface{}
// fundingRequests is a channel used to receive channel initiation
// requests from a local subsystem within the daemon.
fundingRequests chan *initFundingMsg
// newChanBarriers is a map from a channel ID to a 'barrier' which will
// be signalled once the channel is fully open. This barrier acts as a
// synchronization point for any incoming/outgoing HTLCs before the
// channel has been fully opened.
barrierMtx sync.RWMutex
newChanBarriers map[lnwire.ChannelID]chan struct{}
localDiscoveryMtx sync.Mutex
localDiscoverySignals map[lnwire.ChannelID]chan struct{}
handleFundingLockedMtx sync.RWMutex
handleFundingLockedBarriers map[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 fundingLocked is not yet
// successfully sent to the other peer.
markedOpen channelOpeningState = iota
// fundingLockedSent is the opening state of a channel if the
// fundingLocked message has successfully been sent to the other peer,
// but we still haven't announced the channel to the network.
fundingLockedSent
)
var (
// channelOpeningStateBucket is the database bucket used to store the
// channelOpeningState for each channel that is currently in the process
// of being opened.
channelOpeningStateBucket = []byte("channelOpeningState")
// ErrChannelNotFound is returned when we are looking for a specific
// channel opening state in the FundingManager's internal database, but
// the channel in question is not considered being in an opening state.
ErrChannelNotFound = fmt.Errorf("channel not found in db")
)
// newFundingManager creates and initializes a new instance of the
// fundingManager.
func newFundingManager(cfg fundingConfig) (*fundingManager, error) {
return &fundingManager{
cfg: &cfg,
chanIDKey: cfg.TempChanIDSeed,
activeReservations: make(map[serializedPubKey]pendingChannels),
signedReservations: make(map[lnwire.ChannelID][32]byte),
newChanBarriers: make(map[lnwire.ChannelID]chan struct{}),
fundingMsgs: make(chan interface{}, msgBufferSize),
fundingRequests: make(chan *initFundingMsg, msgBufferSize),
localDiscoverySignals: make(map[lnwire.ChannelID]chan struct{}),
handleFundingLockedBarriers: make(map[lnwire.ChannelID]struct{}),
queries: make(chan interface{}, 1),
quit: make(chan struct{}),
}, nil
}
// Start launches all helper goroutines required for handling requests sent
// to the funding manager.
func (f *fundingManager) Start() error {
if atomic.AddInt32(&f.started, 1) != 1 { // TODO(roasbeef): CAS instead
return nil
}
fndgLog.Tracef("Funding manager running")
// 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
pendingChannels, err := f.cfg.Wallet.Cfg.Database.FetchPendingChannels()
if err != nil {
return err
}
// 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 will also launch waitForFundingConfirmation to wait for
// the channel's funding transaction to be confirmed on the blockchain.
for _, channel := range pendingChannels {
f.barrierMtx.Lock()
fndgLog.Tracef("Loading pending ChannelPoint(%v), creating chan "+
"barrier", channel.FundingOutpoint)
chanID := lnwire.NewChanIDFromOutPoint(&channel.FundingOutpoint)
f.newChanBarriers[chanID] = make(chan struct{})
f.barrierMtx.Unlock()
f.localDiscoverySignals[chanID] = make(chan struct{})
confChan := make(chan *lnwire.ShortChannelID)
timeoutChan := make(chan struct{})
go func(ch *channeldb.OpenChannel) {
go f.waitForFundingWithTimeout(ch, confChan, timeoutChan)
select {
case <-timeoutChan:
// Timeout waiting for the funding transaction
// to confirm, so we forget the channel and
// delete it from the database.
closeInfo := &channeldb.ChannelCloseSummary{
ChanPoint: ch.FundingOutpoint,
RemotePub: ch.IdentityPub,
CloseType: channeldb.FundingCanceled,
}
if err := ch.CloseChannel(closeInfo); err != nil {
fndgLog.Errorf("Failed closing channel "+
"%v: %v", ch.FundingOutpoint, err)
}
case <-f.quit:
// The fundingManager is shutting down, and will
// resume wait on startup.
case shortChanID, ok := <-confChan:
if !ok {
fndgLog.Errorf("waiting for funding" +
"confirmation failed")
return
}
// Success, funding transaction was confirmed.
err := f.handleFundingConfirmation(ch, shortChanID)
if err != nil {
fndgLog.Errorf("failed to handle funding"+
"confirmation: %v", err)
return
}
}
}(channel)
}
// Fetch all our open channels, and make sure they all finalized the
// opening process.
// TODO(halseth): this check is only done on restart atm, but should
// also be done if a peer that disappeared during the opening process
// reconnects.
openChannels, err := f.cfg.Wallet.Cfg.Database.FetchAllChannels()
if err != nil {
return err
}
for _, channel := range openChannels {
channelState, shortChanID, err := f.getChannelOpeningState(
&channel.FundingOutpoint)
if err == ErrChannelNotFound {
// Channel not in fundingManager's opening database,
// meaning it was successully announced to the network.
continue
} else if err != nil {
return err
}
chanID := lnwire.NewChanIDFromOutPoint(&channel.FundingOutpoint)
fndgLog.Debugf("channel (%v) with opening state %v found",
chanID, channelState)
// Set up the channel barriers again, to make sure
// waitUntilChannelOpen correctly waits until the opening
// process is completely over.
f.barrierMtx.Lock()
fndgLog.Tracef("Loading pending ChannelPoint(%v), "+
"creating chan barrier", channel.FundingOutpoint)
f.newChanBarriers[chanID] = make(chan struct{})
f.barrierMtx.Unlock()
// Set up a localDiscoverySignals to make sure we finish sending
// our own fundingLocked and channel announcements before
// processing a received fundingLocked.
f.localDiscoverySignals[chanID] = make(chan struct{})
// If we did find the channel in the opening state database, we
// have seen the funding transaction being confirmed, but we
// did not finish the rest of the setup procedure before we shut
// down. We handle the remaining steps of this setup by
// continuing the procedure where we left off.
switch channelState {
case markedOpen:
// The funding transaction was confirmed, but we did not
// successfully send the fundingLocked message to the
// peer, so let's do that now.
f.wg.Add(1)
go func() {
defer f.wg.Done()
err := f.handleFundingConfirmation(channel, shortChanID)
if err != nil {
fndgLog.Errorf("failed to handle funding"+
"confirmation: %v", err)
return
}
}()
case fundingLockedSent:
// fundingLocked was sent to peer, but the channel
// announcement was not sent.
f.wg.Add(1)
go func() {
defer f.wg.Done()
lnChannel, err := lnwallet.NewLightningChannel(
nil, nil, f.cfg.FeeEstimator, channel)
if err != nil {
fndgLog.Errorf("error creating "+
"lightning channel: %v", err)
return
}
defer lnChannel.Stop()
err = f.sendChannelAnnouncement(channel, lnChannel,
shortChanID)
if err != nil {
fndgLog.Errorf("error sending channel "+
"announcement: %v", err)
return
}
}()
default:
fndgLog.Errorf("undefined channelState: %v",
channelState)
}
}
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 *fundingManager) Stop() error {
if atomic.AddInt32(&f.stopped, 1) != 1 {
return nil
}
fndgLog.Infof("Funding manager shutting down")
close(f.quit)
f.wg.Wait()
return nil
}
// nextPendingChanID returns the next free pending channel ID to be used to
// identify a particular future channel funding workflow.
func (f *fundingManager) nextPendingChanID() [32]byte {
// Obtain a fresh nonce. We do this by encoding the current nonce
// counter, then incrementing it by one.
f.nonceMtx.Lock()
var nonce [8]byte
binary.LittleEndian.PutUint64(nonce[:], f.chanIDNonce)
f.chanIDNonce++
f.nonceMtx.Unlock()
// 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 [32]byte
zeroes [32]byte
)
salsa20.XORKeyStream(nextChanID[:], zeroes[:], nonce[:], &f.chanIDKey)
return nextChanID
}
type pendingChannel struct {
identityPub *btcec.PublicKey
channelPoint *wire.OutPoint
capacity btcutil.Amount
localBalance btcutil.Amount
remoteBalance btcutil.Amount
}
type pendingChansReq struct {
resp chan []*pendingChannel
err chan error
}
// PendingChannels returns a slice describing all the channels which are
// currently pending at the last state of the funding workflow.
func (f *fundingManager) PendingChannels() ([]*pendingChannel, error) {
respChan := make(chan []*pendingChannel, 1)
errChan := make(chan error)
req := &pendingChansReq{
resp: respChan,
err: errChan,
}
f.queries <- req
return <-respChan, <-errChan
}
// failFundingFlow will fail the active funding flow with the target peer,
// identified by it's unique temporary channel ID. This method is 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 *fundingManager) failFundingFlow(peer *btcec.PublicKey,
tempChanID [32]byte, msg []byte) {
errMsg := &lnwire.Error{
ChanID: tempChanID,
Data: msg,
}
fndgLog.Errorf("Failing funding flow: %v", spew.Sdump(errMsg))
err := f.cfg.SendToPeer(peer, errMsg)
if err != nil {
fndgLog.Errorf("unable to send error message to peer %v", err)
return
}
f.cancelReservationCtx(peer, tempChanID)
return
}
// 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 *fundingManager) reservationCoordinator() {
defer f.wg.Done()
for {
select {
case msg := <-f.fundingMsgs:
switch fmsg := msg.(type) {
case *fundingOpenMsg:
f.handleFundingOpen(fmsg)
case *fundingAcceptMsg:
f.handleFundingAccept(fmsg)
case *fundingCreatedMsg:
f.handleFundingCreated(fmsg)
case *fundingSignedMsg:
f.handleFundingSigned(fmsg)
case *fundingLockedMsg:
f.wg.Add(1)
go f.handleFundingLocked(fmsg)
case *fundingErrorMsg:
f.handleErrorMsg(fmsg)
}
case req := <-f.fundingRequests:
f.handleInitFundingMsg(req)
case req := <-f.queries:
switch msg := req.(type) {
case *pendingChansReq:
f.handlePendingChannels(msg)
}
case <-f.quit:
return
}
}
}
// handlePendingChannels responds to a request for details concerning all
// currently pending channels waiting for the final phase of the funding
// workflow (funding txn confirmation).
func (f *fundingManager) handlePendingChannels(msg *pendingChansReq) {
var pendingChannels []*pendingChannel
dbPendingChannels, err := f.cfg.Wallet.Cfg.Database.FetchPendingChannels()
if err != nil {
msg.resp <- nil
msg.err <- err
return
}
for _, dbPendingChan := range dbPendingChannels {
pendingChan := &pendingChannel{
identityPub: dbPendingChan.IdentityPub,
channelPoint: &dbPendingChan.FundingOutpoint,
capacity: dbPendingChan.Capacity,
localBalance: dbPendingChan.LocalBalance.ToSatoshis(),
remoteBalance: dbPendingChan.RemoteBalance.ToSatoshis(),
}
pendingChannels = append(pendingChannels, pendingChan)
}
msg.resp <- pendingChannels
msg.err <- nil
}
// processFundingOpen sends a message to the fundingManager allowing it to
// initiate the new funding workflow with the source peer.
func (f *fundingManager) processFundingOpen(msg *lnwire.OpenChannel,
peerAddress *lnwire.NetAddress) {
select {
case f.fundingMsgs <- &fundingOpenMsg{msg, peerAddress}:
case <-f.quit:
return
}
}
// handleFundingOpen 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
func (f *fundingManager) handleFundingOpen(fmsg *fundingOpenMsg) {
// Check number of pending channels to be smaller than maximum allowed
// number and send ErrorGeneric to remote peer if condition is
// violated.
peerIDKey := newSerializedKey(fmsg.peerAddress.IdentityKey)
msg := fmsg.msg
amt := msg.FundingAmount
// TODO(roasbeef): modify to only accept a _single_ pending channel per
// block unless white listed
if len(f.activeReservations[peerIDKey]) >= cfg.MaxPendingChannels {
f.failFundingFlow(
fmsg.peerAddress.IdentityKey, fmsg.msg.PendingChannelID,
lnwire.ErrorData{byte(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 {
fndgLog.Errorf("unable to query wallet: %v", err)
return
}
if !isSynced {
f.failFundingFlow(
fmsg.peerAddress.IdentityKey, fmsg.msg.PendingChannelID,
lnwire.ErrorData{byte(lnwire.ErrSynchronizingChain)},
)
return
}
// We'll reject any request to create a channel that's above the
// current soft-limit for channel size.
if msg.FundingAmount > maxFundingAmount {
f.failFundingFlow(
fmsg.peerAddress.IdentityKey, fmsg.msg.PendingChannelID,
lnwire.ErrorData{byte(lnwire.ErrChanTooLarge)},
)
return
}
// TODO(roasbeef): error if funding flow already ongoing
fndgLog.Infof("Recv'd fundingRequest(amt=%v, push=%v, delay=%v, "+
"pendingId=%x) from peer(%x)", amt, msg.PushAmount,
msg.CsvDelay, msg.PendingChannelID,
fmsg.peerAddress.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.
//
// TODO(roasbeef): assuming this was an inbound connection, replace
// port with default advertised port
chainHash := chainhash.Hash(msg.ChainHash)
reservation, err := f.cfg.Wallet.InitChannelReservation(amt, 0,
msg.PushAmount, btcutil.Amount(msg.FeePerKiloWeight),
fmsg.peerAddress.IdentityKey, fmsg.peerAddress.Address,
&chainHash)
if err != nil {
fndgLog.Errorf("Unable to initialize reservation: %v", err)
f.failFundingFlow(fmsg.peerAddress.IdentityKey,
msg.PendingChannelID, []byte(err.Error()))
return
}
// 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 out 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.
numConfsReq := f.cfg.NumRequiredConfs(msg.FundingAmount, msg.PushAmount)
reservation.SetNumConfsRequired(numConfsReq)
// We'll also validate and apply all the constraints the initiating
// party is attempting to dictate for our commitment transaction.
err = reservation.CommitConstraints(
uint16(msg.CsvDelay), msg.MaxAcceptedHTLCs,
msg.MaxValueInFlight, msg.ChannelReserve,
)
if err != nil {
f.failFundingFlow(
fmsg.peerAddress.IdentityKey, fmsg.msg.PendingChannelID,
[]byte(fmt.Sprintf("Unacceptable channel "+
"constraints: %v", err)),
)
return
}
fndgLog.Infof("Requiring %v confirmations for pendingChan(%x): "+
"amt=%v, push_amt=%v", numConfsReq, fmsg.msg.PendingChannelID,
amt, msg.PushAmount)
// Once the reservation has been created successfully, we add it to
// this peers 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)
}
f.activeReservations[peerIDKey][msg.PendingChannelID] = &reservationWithCtx{
reservation: reservation,
chanAmt: amt,
err: make(chan error, 1),
peerAddress: fmsg.peerAddress,
}
f.resMtx.Unlock()
// Using the RequiredRemoteDelay closure, we'll compute the remote CSV
// delay we require given the total amount of funds within the channel.
remoteCsvDelay := f.cfg.RequiredRemoteDelay(amt)
// We'll also generate our required constraints for the remote party,
chanReserve, maxValue, maxHtlcs := reservation.RemoteChanConstraints()
// 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: &channeldb.ChannelConfig{
ChannelConstraints: channeldb.ChannelConstraints{
DustLimit: msg.DustLimit,
MaxPendingAmount: maxValue,
ChanReserve: chanReserve,
MinHTLC: msg.HtlcMinimum,
MaxAcceptedHtlcs: maxHtlcs,
},
CsvDelay: remoteCsvDelay,
MultiSigKey: copyPubKey(msg.FundingKey),
RevocationBasePoint: copyPubKey(msg.RevocationPoint),
PaymentBasePoint: copyPubKey(msg.PaymentPoint),
DelayBasePoint: copyPubKey(msg.DelayedPaymentPoint),
},
}
err = reservation.ProcessSingleContribution(remoteContribution)
if err != nil {
fndgLog.Errorf("unable to add contribution reservation: %v", err)
// TODO(roasbeef): verify only sending sane info over
f.failFundingFlow(fmsg.peerAddress.IdentityKey,
msg.PendingChannelID, []byte(err.Error()))
return
}
fndgLog.Infof("Sending fundingResp for pendingID(%x)",
msg.PendingChannelID)
fndgLog.Debugf("Remote party accepted commitment constraints: %v",
spew.Sdump(remoteContribution.ChannelConfig.ChannelConstraints))
// With the initiator's contribution recorded, respond with our
// contribution in the next message of the workflow.
ourContribution := reservation.OurContribution()
fundingAccept := lnwire.AcceptChannel{
PendingChannelID: msg.PendingChannelID,
DustLimit: ourContribution.DustLimit,
MaxValueInFlight: maxValue,
ChannelReserve: chanReserve,
MinAcceptDepth: uint32(numConfsReq),
HtlcMinimum: ourContribution.MinHTLC,
CsvDelay: uint16(remoteCsvDelay),
MaxAcceptedHTLCs: maxHtlcs,
FundingKey: ourContribution.MultiSigKey,
RevocationPoint: ourContribution.RevocationBasePoint,
PaymentPoint: ourContribution.PaymentBasePoint,
DelayedPaymentPoint: ourContribution.DelayBasePoint,
FirstCommitmentPoint: ourContribution.FirstCommitmentPoint,
}
err = f.cfg.SendToPeer(fmsg.peerAddress.IdentityKey, &fundingAccept)
if err != nil {
fndgLog.Errorf("unable to send funding response to peer: %v", err)
f.failFundingFlow(fmsg.peerAddress.IdentityKey,
msg.PendingChannelID, []byte(err.Error()))
return
}
}
// processFundingAccept sends a message to the fundingManager allowing it to
// continue the second phase of a funding workflow with the target peer.
func (f *fundingManager) processFundingAccept(msg *lnwire.AcceptChannel,
peerAddress *lnwire.NetAddress) {
select {
case f.fundingMsgs <- &fundingAcceptMsg{msg, peerAddress}:
case <-f.quit:
return
}
}
// handleFundingAceept 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.
func (f *fundingManager) handleFundingAccept(fmsg *fundingAcceptMsg) {
msg := fmsg.msg
pendingChanID := fmsg.msg.PendingChannelID
peerKey := fmsg.peerAddress.IdentityKey
resCtx, err := f.getReservationCtx(peerKey, pendingChanID)
if err != nil {
fndgLog.Warnf("Can't find reservation (peerKey:%v, chanID:%v)",
peerKey, pendingChanID)
return
}
fndgLog.Infof("Recv'd fundingResponse for pendingID(%x)", pendingChanID[:])
// 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(msg.MinAcceptDepth))
err = resCtx.reservation.CommitConstraints(
uint16(msg.CsvDelay), msg.MaxAcceptedHTLCs,
msg.MaxValueInFlight, msg.ChannelReserve,
)
if err != nil {
f.failFundingFlow(
fmsg.peerAddress.IdentityKey, fmsg.msg.PendingChannelID,
[]byte(fmt.Sprintf("Unacceptable channel "+
"constraints: %v", err)),
)
return
}
// As they've accepted our channel constraints, we'll regenerate them
// here so we can properly commit their accepted constraints to the
// reservation.
chanReserve, maxValue, maxHtlcs := resCtx.reservation.RemoteChanConstraints()
// 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: &channeldb.ChannelConfig{
ChannelConstraints: channeldb.ChannelConstraints{
DustLimit: msg.DustLimit,
MaxPendingAmount: maxValue,
ChanReserve: chanReserve,
MinHTLC: msg.HtlcMinimum,
MaxAcceptedHtlcs: maxHtlcs,
},
MultiSigKey: copyPubKey(msg.FundingKey),
RevocationBasePoint: copyPubKey(msg.RevocationPoint),
PaymentBasePoint: copyPubKey(msg.PaymentPoint),
DelayBasePoint: copyPubKey(msg.DelayedPaymentPoint),
},
}
remoteContribution.CsvDelay = f.cfg.RequiredRemoteDelay(resCtx.chanAmt)
err = resCtx.reservation.ProcessContribution(remoteContribution)
if err != nil {
fndgLog.Errorf("Unable to process contribution from %v: %v",
fmsg.peerAddress.IdentityKey, err)
f.failFundingFlow(fmsg.peerAddress.IdentityKey,
msg.PendingChannelID, []byte(err.Error()))
resCtx.err <- err
return
}
fndgLog.Infof("pendingChan(%x): remote party proposes num_confs=%v, "+
"csv_delay=%v", pendingChanID[:], msg.MinAcceptDepth, msg.CsvDelay)
fndgLog.Debugf("Remote party accepted commitment constraints: %v",
spew.Sdump(remoteContribution.ChannelConfig.ChannelConstraints))
// 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()
commitSig, err := btcec.ParseSignature(sig, btcec.S256())
if err != nil {
fndgLog.Errorf("Unable to parse signature: %v", err)
f.failFundingFlow(fmsg.peerAddress.IdentityKey,
msg.PendingChannelID, []byte(err.Error()))
resCtx.err <- err
return
}
// 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.
f.barrierMtx.Lock()
channelID := lnwire.NewChanIDFromOutPoint(outPoint)
fndgLog.Debugf("Creating chan barrier for ChanID(%v)", channelID)
f.newChanBarriers[channelID] = make(chan struct{})
f.barrierMtx.Unlock()
// 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] = pendingChanID
f.resMtx.Unlock()
fndgLog.Infof("Generated ChannelPoint(%v) for pendingID(%x)", outPoint,