lnd.xprv/lnwallet/wallet.go

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package lnwallet
import (
"encoding/hex"
"errors"
"fmt"
"math"
"sync"
"sync/atomic"
"github.com/davecgh/go-spew/spew"
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"github.com/lightningnetwork/lnd/chainntfs"
"github.com/lightningnetwork/lnd/chainntfs/btcdnotify"
"github.com/lightningnetwork/lnd/channeldb"
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"github.com/lightningnetwork/lnd/elkrem"
"github.com/roasbeef/btcd/btcjson"
"github.com/roasbeef/btcd/btcec"
"github.com/roasbeef/btcd/txscript"
"github.com/roasbeef/btcd/wire"
"github.com/roasbeef/btcrpcclient"
"github.com/roasbeef/btcutil"
"github.com/roasbeef/btcutil/coinset"
"github.com/roasbeef/btcutil/txsort"
"github.com/roasbeef/btcwallet/chain"
"github.com/roasbeef/btcwallet/waddrmgr"
btcwallet "github.com/roasbeef/btcwallet/wallet"
)
const (
// The size of the buffered queue of requests to the wallet from the
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// outside word.
msgBufferSize = 100
)
var (
// Error types
ErrInsufficientFunds = errors.New("not enough available outputs to " +
"create funding transaction")
// Namespace bucket keys.
lightningNamespaceKey = []byte("ln-wallet")
waddrmgrNamespaceKey = []byte("waddrmgr")
wtxmgrNamespaceKey = []byte("wtxmgr")
)
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// initFundingReserveReq is the first message sent to initiate the workflow
// required to open a payment channel with a remote peer. The initial required
// paramters are configurable accross channels. These paramters are to be chosen
// depending on the fee climate within the network, and time value of funds to
// be locked up within the channel. Upon success a ChannelReservation will be
// created in order to track the lifetime of this pending channel. Outputs
// selected will be 'locked', making them unavailable, for any other pending
// reservations. Therefore, all channels in reservation limbo will be periodically
// after a timeout period in order to avoid "exhaustion" attacks.
// NOTE: The workflow currently assumes fully balanced symmetric channels.
// Meaning both parties must encumber the same amount of funds.
// TODO(roasbeef): zombie reservation sweeper goroutine.
type initFundingReserveMsg struct {
// The number of confirmations required before the channel is considered
// open.
numConfs uint16
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// The amount of funds requested for this channel.
fundingAmount btcutil.Amount
// The total capacity of the channel which includes the amount of funds
// the remote party contributes (if any).
capacity btcutil.Amount
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// The minimum accepted satoshis/KB fee for the funding transaction. In
// order to ensure timely confirmation, it is recomened that this fee
// should be generous, paying some multiple of the accepted base fee
// rate of the network.
// TODO(roasbeef): integrate fee estimation project...
minFeeRate btcutil.Amount
// The ID of the remote node we would like to open a channel with.
// TODO(roasbeef): switch to just reg pubkey?
nodeID [32]byte
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// The delay on the "pay-to-self" output(s) of the commitment transaction.
csvDelay uint32
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// A channel in which all errors will be sent accross. Will be nil if
// this initial set is succesful.
// NOTE: In order to avoid deadlocks, this channel MUST be buffered.
err chan error
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// A ChannelReservation with our contributions filled in will be sent
// accross this channel in the case of a succesfully reservation
// initiation. In the case of an error, this will read a nil pointer.
// NOTE: In order to avoid deadlocks, this channel MUST be buffered.
resp chan *ChannelReservation
}
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// fundingReserveCancelMsg is a message reserved for cancelling an existing
// channel reservation identified by its reservation ID. Cancelling a reservation
// frees its locked outputs up, for inclusion within further reservations.
type fundingReserveCancelMsg struct {
pendingFundingID uint64
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// NOTE: In order to avoid deadlocks, this channel MUST be buffered.
err chan error // Buffered
}
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// addContributionMsg represents a message executing the second phase of the
// channel reservation workflow. This message carries the counterparty's
// "contribution" to the payment channel. In the case that this message is
// processed without generating any errors, then channel reservation will then
// be able to construct the funding tx, both commitment transactions, and
// finally generate signatures for all our inputs to the funding transaction,
// and for the remote node's version of the commitment transaction.
type addContributionMsg struct {
pendingFundingID uint64
// TODO(roasbeef): Should also carry SPV proofs in we're in SPV mode
contribution *ChannelContribution
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// NOTE: In order to avoid deadlocks, this channel MUST be buffered.
err chan error
}
// addSingleContributionMsg represents a message executing the second phase of
// a single funder channel reservation workflow. This messages carries the
// counterparty's "contribution" to the payment channel. As this message is
// sent when on the responding side to a single funder workflow, no further
// action apart from storing the provided contribution is carried out.
type addSingleContributionMsg struct {
pendingFundingID uint64
contribution *ChannelContribution
// NOTE: In order to avoid deadlocks, this channel MUST be buffered.
err chan error
}
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// addCounterPartySigsMsg represents the final message required to complete,
// and 'open' a payment channel. This message carries the counterparty's
// signatures for each of their inputs to the funding transaction, and also a
// signature allowing us to spend our version of the commitment transaction.
// If we're able to verify all the signatures are valid, the funding transaction
// will be broadcast to the network. After the funding transaction gains a
// configurable number of confirmations, the channel is officially considered
// 'open'.
type addCounterPartySigsMsg struct {
pendingFundingID uint64
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// Should be order of sorted inputs that are theirs. Sorting is done
// in accordance to BIP-69:
// https://github.com/bitcoin/bips/blob/master/bip-0069.mediawiki.
theirFundingInputScripts []*InputScript
// This should be 1/2 of the signatures needed to succesfully spend our
// version of the commitment transaction.
theirCommitmentSig []byte
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// NOTE: In order to avoid deadlocks, this channel MUST be buffered.
err chan error
}
// addSingleFunderSigsMsg represents the next-to-last message required to
// complete a single-funder channel workflow. Once the initiator is able to
// construct the funding transaction, they send both the outpoint and a
// signature for our version of the commitment transaction. Once this message
// is processed we (the responder) are able to construct both commitment
// transactions, signing the remote party's version.
type addSingleFunderSigsMsg struct {
pendingFundingID uint64
// fundingOutpoint is the outpoint of the completed funding
// transaction as assembled by the workflow initiator.
fundingOutpoint *wire.OutPoint
// revokeKey is the revocation public key derived by the remote node to
// be used within the initial version of the commitment transaction we
// construct for them.
revokeKey *btcec.PublicKey
// This should be 1/2 of the signatures needed to succesfully spend our
// version of the commitment transaction.
theirCommitmentSig []byte
// NOTE: In order to avoid deadlocks, this channel MUST be buffered.
err chan error
}
// channelOpenMsg is the final message sent to finalize a single funder channel
// workflow to which we are the responder to. This message is sent once the
// remote peer deems the channel open, meaning it has reached a sufficient
// number of confirmations in the blockchain.
type channelOpenMsg struct {
pendingFundingID uint64
// TODO(roasbeef): move verification up to upper layer, yeh?
spvProof []byte
// NOTE: In order to avoid deadlocks, this channel MUST be buffered.
err chan error
}
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// LightningWallet is a domain specific, yet general Bitcoin wallet capable of
// executing workflow required to interact with the Lightning Network. It is
// domain specific in the sense that it understands all the fancy scripts used
// within the Lightning Network, channel lifetimes, etc. However, it embedds a
// general purpose Bitcoin wallet within it. Therefore, it is also able to serve
// as a regular Bitcoin wallet which uses HD keys. The wallet is highly concurrent
// internally. All communication, and requests towards the wallet are
// dispatched as messages over channels, ensuring thread safety across all
// operations. Interaction has been designed independant of any peer-to-peer
// communication protocol, allowing the wallet to be self-contained and embeddable
// within future projects interacting with the Lightning Network.
// NOTE: At the moment the wallet requires a btcd full node, as it's dependant
// on btcd's websockets notifications as even triggers during the lifetime of
// a channel. However, once the chainntnfs package is complete, the wallet
// will be compatible with multiple RPC/notification services such as Electrum,
// Bitcoin Core + ZeroMQ, etc. Eventually, the wallet won't require a full-node
// at all, as SPV support is integrated inot btcwallet.
type LightningWallet struct {
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// This mutex is to be held when generating external keys to be used
// as multi-sig, and commitment keys within the channel.
KeyGenMtx sync.RWMutex
// This mutex MUST be held when performing coin selection in order to
// avoid inadvertently creating multiple funding transaction which
// double spend inputs accross each other.
coinSelectMtx sync.RWMutex
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// A wrapper around a namespace within boltdb reserved for ln-based
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// wallet meta-data. See the 'channeldb' package for further
// information.
channelDB *channeldb.DB
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// Used by in order to obtain notifications about funding transaction
// reaching a specified confirmation depth, and to catch
// counterparty's broadcasting revoked commitment states.
// TODO(roasbeef): needs to be stripped out from wallet
ChainNotifier chainntnfs.ChainNotifier
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// The core wallet, all non Lightning Network specific interaction is
// proxied to the internal wallet.
*btcwallet.Wallet
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// An active RPC connection to a full-node. In the case of a btcd node,
// websockets are used for notifications. If using Bitcoin Core,
// notifications are either generated via long-polling or the usage of
// ZeroMQ.
// TODO(roasbeef): make into interface need: getrawtransaction + gettxout
// * getrawtransaction -> verify proof of channel links
// * gettxout -> verify inputs to funding tx exist and are unspent
rpc *chain.RPCClient
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// All messages to the wallet are to be sent accross this channel.
msgChan chan interface{}
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// Incomplete payment channels are stored in the map below. An intent
// to create a payment channel is tracked as a "reservation" within
// limbo. Once the final signatures have been exchanged, a reservation
// is removed from limbo. Each reservation is tracked by a unique
// monotonically integer. All requests concerning the channel MUST
// carry a valid, active funding ID.
fundingLimbo map[uint64]*ChannelReservation
nextFundingID uint64
limboMtx sync.RWMutex
// TODO(roasbeef): zombie garbage collection routine to solve
// lost-object/starvation problem/attack.
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cfg *Config
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started int32
shutdown int32
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quit chan struct{}
wg sync.WaitGroup
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// TODO(roasbeef): handle wallet lock/unlock
}
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// NewLightningWallet creates/opens and initializes a LightningWallet instance.
// If the wallet has never been created (according to the passed dataDir), first-time
// setup is executed.
func NewLightningWallet(config *Config, cdb *channeldb.DB) (*LightningWallet, error) {
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// Ensure the wallet exists or create it when the create flag is set.
netDir := networkDir(config.DataDir, config.NetParams)
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var pubPass []byte
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if config.PublicPass == nil {
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pubPass = defaultPubPassphrase
} else {
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pubPass = config.PublicPass
}
loader := btcwallet.NewLoader(config.NetParams, netDir)
walletExists, err := loader.WalletExists()
if err != nil {
return nil, err
}
var createID bool
var wallet *btcwallet.Wallet
if !walletExists {
// Wallet has never been created, perform initial set up.
wallet, err = loader.CreateNewWallet(pubPass, config.PrivatePass,
config.HdSeed)
if err != nil {
return nil, err
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}
createID = true
} else {
// Wallet has been created and been initialized at this point, open it
// along with all the required DB namepsaces, and the DB itself.
wallet, err = loader.OpenExistingWallet(pubPass, false)
if err != nil {
return nil, err
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}
}
if err := wallet.Manager.Unlock(config.PrivatePass); err != nil {
return nil, err
}
// If we just created the wallet, then reserve, and store a key for
// our ID within the Lightning Network.
if createID {
account := uint32(waddrmgr.DefaultAccountNum)
adrs, err := wallet.Manager.NextInternalAddresses(account, 1, waddrmgr.WitnessPubKey)
if err != nil {
return nil, err
}
idPubkeyHash := adrs[0].Address().ScriptAddress()
if err := cdb.PutIdKey(idPubkeyHash); err != nil {
return nil, err
}
log.Infof("stored identity key pubkey hash in channeldb")
}
// Create a special websockets rpc client for btcd which will be used
// by the wallet for notifications, calls, etc.
rpcc, err := chain.NewRPCClient(config.NetParams, config.RpcHost,
config.RpcUser, config.RpcPass, config.CACert, false, 20)
if err != nil {
return nil, err
}
// Using the same authentication info, create a config for a second
// rpcclient which will be used by the current default chain
// notifier implemenation.
rpcConfig := &btcrpcclient.ConnConfig{
Host: config.RpcHost,
Endpoint: "ws",
User: config.RpcUser,
Pass: config.RpcPass,
Certificates: config.CACert,
DisableTLS: false,
DisableConnectOnNew: true,
DisableAutoReconnect: false,
}
chainNotifier, err := btcdnotify.NewBtcdNotifier(rpcConfig)
if err != nil {
return nil, err
}
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// TODO(roasbeef): logging
return &LightningWallet{
ChainNotifier: chainNotifier,
rpc: rpcc,
Wallet: wallet,
channelDB: cdb,
msgChan: make(chan interface{}, msgBufferSize),
// TODO(roasbeef): make this atomic.Uint32 instead? Which is
// faster, locks or CAS? I'm guessing CAS because assembly:
// * https://golang.org/src/sync/atomic/asm_amd64.s
nextFundingID: 0,
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cfg: config,
fundingLimbo: make(map[uint64]*ChannelReservation),
quit: make(chan struct{}),
}, nil
}
// Startup establishes a connection to the RPC source, and spins up all
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// goroutines required to handle incoming messages.
func (l *LightningWallet) Startup() error {
// Already started?
if atomic.AddInt32(&l.started, 1) != 1 {
return nil
}
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// Establish an RPC connection in additino to starting the goroutines
// in the underlying wallet.
if err := l.rpc.Start(); err != nil {
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return err
}
l.Start()
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// Start the notification server. This is used so channel managment
// goroutines can be notified when a funding transaction reaches a
// sufficient number of confirmations, or when the input for the funding
// transaction is spent in an attempt at an uncooperative close by the
// counter party.
if err := l.ChainNotifier.Start(); err != nil {
return err
}
// Pass the rpc client into the wallet so it can sync up to the current
// main chain.
l.SynchronizeRPC(l.rpc)
l.wg.Add(1)
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// TODO(roasbeef): multiple request handlers?
go l.requestHandler()
return nil
}
// Shutdown gracefully stops the wallet, and all active goroutines.
func (l *LightningWallet) Shutdown() error {
if atomic.AddInt32(&l.shutdown, 1) != 1 {
return nil
}
// Signal the underlying wallet controller to shutdown, waiting until
// all active goroutines have been shutdown.
l.Stop()
l.WaitForShutdown()
l.rpc.Shutdown()
l.ChainNotifier.Stop()
close(l.quit)
l.wg.Wait()
return nil
}
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// requestHandler is the primary goroutine(s) resposible for handling, and
// dispatching relies to all messages.
func (l *LightningWallet) requestHandler() {
out:
for {
select {
case m := <-l.msgChan:
switch msg := m.(type) {
case *initFundingReserveMsg:
l.handleFundingReserveRequest(msg)
case *fundingReserveCancelMsg:
l.handleFundingCancelRequest(msg)
case *addSingleContributionMsg:
l.handleSingleContribution(msg)
case *addContributionMsg:
l.handleContributionMsg(msg)
case *addSingleFunderSigsMsg:
l.handleSingleFunderSigs(msg)
case *addCounterPartySigsMsg:
l.handleFundingCounterPartySigs(msg)
case *channelOpenMsg:
l.handleChannelOpen(msg)
}
case <-l.quit:
// TODO: do some clean up
break out
}
}
l.wg.Done()
}
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// InitChannelReservation kicks off the 3-step workflow required to succesfully
// open a payment channel with a remote node. As part of the funding
// reservation, the inputs selected for the funding transaction are 'locked'.
// This ensures that multiple channel reservations aren't double spending the
// same inputs in the funding transaction. If reservation initialization is
// succesful, a ChannelReservation containing our completed contribution is
// returned. Our contribution contains all the items neccessary to allow the
// counter party to build the funding transaction, and both versions of the
// commitment transaction. Otherwise, an error occured a nil pointer along with
// an error are returned.
//
// Once a ChannelReservation has been obtained, two additional steps must be
// processed before a payment channel can be considered 'open'. The second step
// validates, and processes the counterparty's channel contribution. The third,
// and final step verifies all signatures for the inputs of the funding
// transaction, and that the signature we records for our version of the
// commitment transaction is valid.
func (l *LightningWallet) InitChannelReservation(capacity,
ourFundAmt btcutil.Amount, theirID [32]byte, numConfs uint16,
csvDelay uint32) (*ChannelReservation, error) {
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errChan := make(chan error, 1)
respChan := make(chan *ChannelReservation, 1)
l.msgChan <- &initFundingReserveMsg{
capacity: capacity,
numConfs: numConfs,
fundingAmount: ourFundAmt,
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csvDelay: csvDelay,
nodeID: theirID,
err: errChan,
resp: respChan,
}
return <-respChan, <-errChan
}
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// handleFundingReserveRequest processes a message intending to create, and
// validate a funding reservation request.
func (l *LightningWallet) handleFundingReserveRequest(req *initFundingReserveMsg) {
// Create a limbo and record entry for this newly pending funding request.
l.limboMtx.Lock()
id := l.nextFundingID
reservation := newChannelReservation(req.capacity, req.fundingAmount,
req.minFeeRate, l, id, req.numConfs)
l.nextFundingID++
l.fundingLimbo[id] = reservation
l.limboMtx.Unlock()
// Grab the mutex on the ChannelReservation to ensure thead-safety
reservation.Lock()
defer reservation.Unlock()
reservation.partialState.TheirLNID = req.nodeID
ourContribution := reservation.ourContribution
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ourContribution.CsvDelay = req.csvDelay
reservation.partialState.LocalCsvDelay = req.csvDelay
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// If we're on the receiving end of a single funder channel then we
// don't need to perform any coin selection. Otherwise, attempt to
// obtain enough coins to meet the required funding amount.
if req.fundingAmount != 0 {
if err := l.selectCoinsAndChange(req.fundingAmount,
ourContribution); err != nil {
req.err <- err
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req.resp <- nil
return
}
}
// Grab two fresh keys from our HD chain, one will be used for the
// multi-sig funding transaction, and the other for the commitment
// transaction.
multiSigKey, err := l.getNextRawKey()
if err != nil {
req.err <- err
req.resp <- nil
return
}
commitKey, err := l.getNextRawKey()
if err != nil {
req.err <- err
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req.resp <- nil
return
}
reservation.partialState.OurMultiSigKey = multiSigKey
ourContribution.MultiSigKey = multiSigKey.PubKey()
reservation.partialState.OurCommitKey = commitKey
ourContribution.CommitKey = commitKey.PubKey()
// Generate a fresh address to be used in the case of a cooperative
// channel close.
deliveryAddress, err := l.NewAddress(waddrmgr.DefaultAccountNum,
waddrmgr.WitnessPubKey)
if err != nil {
req.err <- err
req.resp <- nil
return
}
deliveryScript, err := txscript.PayToAddrScript(deliveryAddress)
if err != nil {
req.err <- err
req.resp <- nil
return
}
reservation.partialState.OurDeliveryScript = deliveryScript
ourContribution.DeliveryAddress = deliveryAddress
// Funding reservation request succesfully handled. The funding inputs
// will be marked as unavailable until the reservation is either
// completed, or cancecled.
req.resp <- reservation
req.err <- nil
}
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// handleFundingReserveCancel cancels an existing channel reservation. As part
// of the cancellation, outputs previously selected as inputs for the funding
// transaction via coin selection are freed allowing future reservations to
// include them.
func (l *LightningWallet) handleFundingCancelRequest(req *fundingReserveCancelMsg) {
// TODO(roasbeef): holding lock too long
l.limboMtx.Lock()
defer l.limboMtx.Unlock()
pendingReservation, ok := l.fundingLimbo[req.pendingFundingID]
if !ok {
// TODO(roasbeef): make new error, "unkown funding state" or something
req.err <- fmt.Errorf("attempted to cancel non-existant funding state")
return
}
// Grab the mutex on the ChannelReservation to ensure thead-safety
pendingReservation.Lock()
defer pendingReservation.Unlock()
// Mark all previously locked outpoints as usuable for future funding
// requests.
for _, unusedInput := range pendingReservation.ourContribution.Inputs {
l.UnlockOutpoint(unusedInput.PreviousOutPoint)
}
// TODO(roasbeef): is it even worth it to keep track of unsed keys?
// TODO(roasbeef): Is it possible to mark the unused change also as
// available?
delete(l.fundingLimbo, req.pendingFundingID)
req.err <- nil
}
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// handleFundingCounterPartyFunds processes the second workflow step for the
// lifetime of a channel reservation. Upon completion, the reservation will
// carry a completed funding transaction (minus the counterparty's input
// signatures), both versions of the commitment transaction, and our signature
// for their version of the commitment transaction.
func (l *LightningWallet) handleContributionMsg(req *addContributionMsg) {
l.limboMtx.Lock()
pendingReservation, ok := l.fundingLimbo[req.pendingFundingID]
l.limboMtx.Unlock()
if !ok {
req.err <- fmt.Errorf("attempted to update non-existant funding state")
return
}
// Grab the mutex on the ChannelReservation to ensure thead-safety
pendingReservation.Lock()
defer pendingReservation.Unlock()
// Create a blank, fresh transaction. Soon to be a complete funding
// transaction which will allow opening a lightning channel.
pendingReservation.fundingTx = wire.NewMsgTx()
fundingTx := pendingReservation.fundingTx
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// Some temporary variables to cut down on the resolution verbosity.
pendingReservation.theirContribution = req.contribution
theirContribution := req.contribution
ourContribution := pendingReservation.ourContribution
// Add all multi-party inputs and outputs to the transaction.
for _, ourInput := range ourContribution.Inputs {
fundingTx.AddTxIn(ourInput)
}
for _, theirInput := range theirContribution.Inputs {
fundingTx.AddTxIn(theirInput)
}
for _, ourChangeOutput := range ourContribution.ChangeOutputs {
fundingTx.AddTxOut(ourChangeOutput)
}
for _, theirChangeOutput := range theirContribution.ChangeOutputs {
fundingTx.AddTxOut(theirChangeOutput)
}
ourKey := pendingReservation.partialState.OurMultiSigKey
theirKey := theirContribution.MultiSigKey
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// Finally, add the 2-of-2 multi-sig output which will set up the lightning
// channel.
channelCapacity := int64(pendingReservation.partialState.Capacity)
redeemScript, multiSigOut, err := genFundingPkScript(ourKey.PubKey().SerializeCompressed(),
theirKey.SerializeCompressed(), channelCapacity)
if err != nil {
req.err <- err
return
}
pendingReservation.partialState.FundingRedeemScript = redeemScript
// Register intent for notifications related to the funding output.
// This'll allow us to properly track the number of confirmations the
// funding tx has once it has been broadcasted.
// TODO(roasbeef): remove
lastBlock := l.Manager.SyncedTo()
scriptAddr, err := l.Manager.ImportScript(redeemScript, &lastBlock)
if err != nil {
req.err <- err
return
}
if err := l.rpc.NotifyReceived([]btcutil.Address{scriptAddr.Address()}); err != nil {
req.err <- err
return
}
// Sort the transaction. Since both side agree to a cannonical
// ordering, by sorting we no longer need to send the entire
// transaction. Only signatures will be exchanged.
fundingTx.AddTxOut(multiSigOut)
txsort.InPlaceSort(pendingReservation.fundingTx)
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// Next, sign all inputs that are ours, collecting the signatures in
// order of the inputs.
pendingReservation.ourFundingInputScripts = make([]*InputScript, 0, len(ourContribution.Inputs))
hashCache := txscript.NewTxSigHashes(fundingTx)
for i, txIn := range fundingTx.TxIn {
// Does the wallet know about the txin?
txDetail, _ := l.TxStore.TxDetails(&txIn.PreviousOutPoint.Hash)
if txDetail == nil {
continue
}
// Is this our txin?
prevIndex := txIn.PreviousOutPoint.Index
prevOut := txDetail.TxRecord.MsgTx.TxOut[prevIndex]
_, addrs, _, _ := txscript.ExtractPkScriptAddrs(prevOut.PkScript, l.cfg.NetParams)
apkh := addrs[0]
ai, err := l.Manager.Address(apkh)
if err != nil {
req.err <- fmt.Errorf("cannot get address info: %v", err)
return
}
pka := ai.(waddrmgr.ManagedPubKeyAddress)
privKey, err := pka.PrivKey()
if err != nil {
req.err <- fmt.Errorf("cannot get private key: %v", err)
return
}
var witnessProgram []byte
inputScript := &InputScript{}
// If we're spending p2wkh output nested within a p2sh output,
// then we'll need to attach a sigScript in addition to witness
// data.
if pka.IsNestedWitness() {
pubKey := privKey.PubKey()
pubKeyHash := btcutil.Hash160(pubKey.SerializeCompressed())
// Next, we'll generate a valid sigScript that'll allow us to spend
// the p2sh output. The sigScript will contain only a single push of
// the p2wkh witness program corresponding to the matching public key
// of this address.
p2wkhAddr, err := btcutil.NewAddressWitnessPubKeyHash(pubKeyHash,
l.cfg.NetParams)
if err != nil {
req.err <- fmt.Errorf("unable to create p2wkh addr: %v", err)
return
}
witnessProgram, err = txscript.PayToAddrScript(p2wkhAddr)
if err != nil {
req.err <- fmt.Errorf("unable to create witness program: %v", err)
return
}
bldr := txscript.NewScriptBuilder()
bldr.AddData(witnessProgram)
sigScript, err := bldr.Script()
if err != nil {
req.err <- fmt.Errorf("unable to create scriptsig: %v", err)
return
}
txIn.SignatureScript = sigScript
inputScript.ScriptSig = sigScript
} else {
witnessProgram = prevOut.PkScript
}
// Generate a valid witness stack for the input.
inputValue := prevOut.Value
witnessScript, err := txscript.WitnessScript(fundingTx, hashCache, i,
inputValue, witnessProgram, txscript.SigHashAll, privKey, true)
if err != nil {
req.err <- fmt.Errorf("cannot create witnessscript: %s", err)
return
}
txIn.Witness = witnessScript
inputScript.Witness = witnessScript
pendingReservation.ourFundingInputScripts = append(
pendingReservation.ourFundingInputScripts,
inputScript,
)
}
// Locate the index of the multi-sig outpoint in order to record it
// since the outputs are cannonically sorted. If this is a sigle funder
// workflow, then we'll also need to send this to the remote node.
fundingTxID := fundingTx.TxSha()
_, multiSigIndex := findScriptOutputIndex(fundingTx, multiSigOut.PkScript)
fundingOutpoint := wire.NewOutPoint(&fundingTxID, multiSigIndex)
pendingReservation.partialState.FundingOutpoint = fundingOutpoint
// Initialize an empty sha-chain for them, tracking the current pending
// revocation hash (we don't yet know the pre-image so we can't add it
// to the chain).
e := &elkrem.ElkremReceiver{}
pendingReservation.partialState.RemoteElkrem = e
pendingReservation.partialState.TheirCurrentRevocation = theirContribution.RevocationKey
// Now that we have their commitment key, we can create the revocation
// key for the first version of our commitment transaction. To do so,
// we'll first create our elkrem root, then grab the first pre-iamge
// from it.
elkremRoot := deriveElkremRoot(ourKey, theirKey)
elkremSender := elkrem.NewElkremSender(elkremRoot)
pendingReservation.partialState.LocalElkrem = elkremSender
firstPreimage, err := elkremSender.AtIndex(0)
if err != nil {
req.err <- err
return
}
theirCommitKey := theirContribution.CommitKey
ourRevokeKey := deriveRevocationPubkey(theirCommitKey, firstPreimage[:])
// Create the txIn to our commitment transaction; required to construct
// the commitment transactions.
fundingTxIn := wire.NewTxIn(wire.NewOutPoint(&fundingTxID, multiSigIndex), nil, nil)
// With the funding tx complete, create both commitment transactions.
// TODO(roasbeef): much cleanup + de-duplication
pendingReservation.fundingLockTime = theirContribution.CsvDelay
ourBalance := ourContribution.FundingAmount
theirBalance := theirContribution.FundingAmount
ourCommitKey := ourContribution.CommitKey
ourCommitTx, err := createCommitTx(fundingTxIn, ourCommitKey, theirCommitKey,
ourRevokeKey, ourContribution.CsvDelay,
ourBalance, theirBalance)
if err != nil {
req.err <- err
return
}
theirCommitTx, err := createCommitTx(fundingTxIn, theirCommitKey, ourCommitKey,
theirContribution.RevocationKey, theirContribution.CsvDelay,
theirBalance, ourBalance)
if err != nil {
req.err <- err
return
}
// Sort both transactions according to the agreed upon cannonical
// ordering. This lets us skip sending the entire transaction over,
// instead we'll just send signatures.
txsort.InPlaceSort(ourCommitTx)
txsort.InPlaceSort(theirCommitTx)
deliveryScript, err := txscript.PayToAddrScript(theirContribution.DeliveryAddress)
if err != nil {
req.err <- err
return
}
2015-12-28 23:14:00 +03:00
// Record newly available information witin the open channel state.
pendingReservation.partialState.RemoteCsvDelay = theirContribution.CsvDelay
pendingReservation.partialState.TheirDeliveryScript = deliveryScript
pendingReservation.partialState.ChanID = fundingOutpoint
pendingReservation.partialState.TheirCommitKey = theirCommitKey
pendingReservation.partialState.TheirMultiSigKey = theirContribution.MultiSigKey
pendingReservation.partialState.OurCommitTx = ourCommitTx
pendingReservation.ourContribution.RevocationKey = ourRevokeKey
// Generate a signature for their version of the initial commitment
// transaction.
hashCache = txscript.NewTxSigHashes(theirCommitTx)
channelBalance := pendingReservation.partialState.Capacity
sigTheirCommit, err := txscript.RawTxInWitnessSignature(theirCommitTx, hashCache, 0,
int64(channelBalance), redeemScript, txscript.SigHashAll, ourKey)
if err != nil {
req.err <- err
return
}
pendingReservation.ourCommitmentSig = sigTheirCommit
req.err <- nil
}
// handleSingleContribution is called as the second step to a single funder
// workflow to which we are the responder. It simply saves the remote peer's
// contribution to the channel, as solely the remote peer will contribute any
// funds to the channel.
func (l *LightningWallet) handleSingleContribution(req *addSingleContributionMsg) {
l.limboMtx.Lock()
pendingReservation, ok := l.fundingLimbo[req.pendingFundingID]
l.limboMtx.Unlock()
if !ok {
req.err <- fmt.Errorf("attempted to update non-existant funding state")
return
}
// Grab the mutex on the ChannelReservation to ensure thead-safety
pendingReservation.Lock()
defer pendingReservation.Unlock()
// Simply record the counterparty's contribution into the pending
// reservation data as they'll be solely funding the channel entirely.
pendingReservation.theirContribution = req.contribution
theirContribution := pendingReservation.theirContribution
// Additionally, we can now also record the redeem script of the
// funding transaction.
// TODO(roasbeef): switch to proper pubkey derivation
ourKey := pendingReservation.partialState.OurMultiSigKey
theirKey := theirContribution.MultiSigKey
channelCapacity := int64(pendingReservation.partialState.Capacity)
redeemScript, _, err := genFundingPkScript(ourKey.PubKey().SerializeCompressed(),
theirKey.SerializeCompressed(), channelCapacity)
if err != nil {
req.err <- err
return
}
pendingReservation.partialState.FundingRedeemScript = redeemScript
// Now that we know their commitment key, we can create the revocation
// key for our version of the initial commitment transaction.
elkremRoot := deriveElkremRoot(ourKey, theirKey)
elkremSender := elkrem.NewElkremSender(elkremRoot)
firstPreimage, err := elkremSender.AtIndex(0)
if err != nil {
req.err <- err
return
}
pendingReservation.partialState.LocalElkrem = elkremSender
theirCommitKey := theirContribution.CommitKey
ourRevokeKey := deriveRevocationPubkey(theirCommitKey, firstPreimage[:])
// Initialize an empty sha-chain for them, tracking the current pending
// revocation hash (we don't yet know the pre-image so we can't add it
// to the chain).
remoteElkrem := &elkrem.ElkremReceiver{}
pendingReservation.partialState.RemoteElkrem = remoteElkrem
// Record the counterpaty's remaining contributions to the channel,
// converting their delivery address into a public key script.
deliveryScript, err := txscript.PayToAddrScript(theirContribution.DeliveryAddress)
if err != nil {
req.err <- err
return
}
pendingReservation.partialState.RemoteCsvDelay = theirContribution.CsvDelay
pendingReservation.partialState.TheirDeliveryScript = deliveryScript
pendingReservation.partialState.TheirCommitKey = theirContribution.CommitKey
pendingReservation.partialState.TheirMultiSigKey = theirContribution.MultiSigKey
pendingReservation.ourContribution.RevocationKey = ourRevokeKey
req.err <- nil
return
}
2015-12-28 23:14:00 +03:00
// handleFundingCounterPartySigs is the final step in the channel reservation
// workflow. During this setp, we validate *all* the received signatures for
// inputs to the funding transaction. If any of these are invalid, we bail,
// and forcibly cancel this funding request. Additionally, we ensure that the
// signature we received from the counterparty for our version of the commitment
// transaction allows us to spend from the funding output with the addition of
// our signature.
func (l *LightningWallet) handleFundingCounterPartySigs(msg *addCounterPartySigsMsg) {
l.limboMtx.RLock()
pendingReservation, ok := l.fundingLimbo[msg.pendingFundingID]
l.limboMtx.RUnlock()
if !ok {
msg.err <- fmt.Errorf("attempted to update non-existant funding state")
return
}
// Grab the mutex on the ChannelReservation to ensure thead-safety
pendingReservation.Lock()
defer pendingReservation.Unlock()
// Now we can complete the funding transaction by adding their
// signatures to their inputs.
pendingReservation.theirFundingInputScripts = msg.theirFundingInputScripts
inputScripts := msg.theirFundingInputScripts
fundingTx := pendingReservation.fundingTx
sigIndex := 0
fundingHashCache := txscript.NewTxSigHashes(fundingTx)
for i, txin := range fundingTx.TxIn {
if len(inputScripts) != 0 && len(txin.Witness) == 0 {
// Attach the input scripts so we can verify it below.
txin.Witness = inputScripts[sigIndex].Witness
txin.SignatureScript = inputScripts[sigIndex].ScriptSig
// Fetch the alleged previous output along with the
// pkscript referenced by this input.
prevOut := txin.PreviousOutPoint
output, err := l.rpc.GetTxOut(&prevOut.Hash, prevOut.Index, false)
if output == nil {
msg.err <- fmt.Errorf("input to funding tx does not exist: %v", err)
return
}
pkScript, err := hex.DecodeString(output.ScriptPubKey.Hex)
if err != nil {
msg.err <- err
return
}
// Sadly, gettxout returns the output value in BTC
// instead of satoshis.
inputValue := int64(output.Value) * 1e8
// Ensure that the witness+sigScript combo is valid.
vm, err := txscript.NewEngine(pkScript,
fundingTx, i, txscript.StandardVerifyFlags, nil,
fundingHashCache, inputValue)
if err != nil {
// TODO(roasbeef): cancel at this stage if invalid sigs?
msg.err <- fmt.Errorf("cannot create script engine: %s", err)
return
}
if err = vm.Execute(); err != nil {
msg.err <- fmt.Errorf("cannot validate transaction: %s", err)
return
}
sigIndex++
}
}
// At this point, we can also record and verify their signature for our
// commitment transaction.
pendingReservation.theirCommitmentSig = msg.theirCommitmentSig
commitTx := pendingReservation.partialState.OurCommitTx
theirKey := pendingReservation.theirContribution.MultiSigKey
ourKey := pendingReservation.partialState.OurMultiSigKey
// Re-generate both the redeemScript and p2sh output. We sign the
// redeemScript script, but include the p2sh output as the subscript
// for verification.
redeemScript := pendingReservation.partialState.FundingRedeemScript
p2wsh, err := witnessScriptHash(redeemScript)
if err != nil {
msg.err <- err
return
}
// First, we sign our copy of the commitment transaction ourselves.
channelValue := int64(pendingReservation.partialState.Capacity)
hashCache := txscript.NewTxSigHashes(commitTx)
ourCommitSig, err := txscript.RawTxInWitnessSignature(commitTx, hashCache, 0,
channelValue, redeemScript, txscript.SigHashAll, ourKey)
if err != nil {
msg.err <- err
return
}
// Next, create the spending scriptSig, and then verify that the script
// is complete, allowing us to spend from the funding transaction.
theirCommitSig := msg.theirCommitmentSig
ourKeySer := ourKey.PubKey().SerializeCompressed()
theirKeySer := theirKey.SerializeCompressed()
witness := spendMultiSig(redeemScript, ourKeySer, ourCommitSig,
theirKeySer, theirCommitSig)
// Finally, create an instance of a Script VM, and ensure that the
// Script executes succesfully.
commitTx.TxIn[0].Witness = witness
vm, err := txscript.NewEngine(p2wsh,
commitTx, 0, txscript.StandardVerifyFlags, nil,
nil, channelValue)
if err != nil {
msg.err <- err
return
}
if err := vm.Execute(); err != nil {
msg.err <- fmt.Errorf("counterparty's commitment signature is invalid: %v", err)
return
}
// Strip and store the signature to ensure that our commitment
// transaction doesn't stay hot.
commitTx.TxIn[0].Witness = nil
pendingReservation.partialState.OurCommitSig = theirCommitSig
// Funding complete, this entry can be removed from limbo.
l.limboMtx.Lock()
delete(l.fundingLimbo, pendingReservation.reservationID)
// TODO(roasbeef): unlock outputs here, Store.InsertTx will handle marking
// input in unconfirmed tx, so future coin selects don't pick it up
// * also record location of change address so can use AddCredit
l.limboMtx.Unlock()
log.Infof("Broadcasting funding tx for ChannelPoint(%v): %v",
pendingReservation.partialState.FundingOutpoint,
spew.Sdump(fundingTx))
// Broacast the finalized funding transaction to the network.
if err := l.PublishTransaction(fundingTx); err != nil {
msg.err <- err
return
}
// Add the complete funding transaction to the DB, in it's open bucket
// which will be used for the lifetime of this channel.
if err := pendingReservation.partialState.FullSync(); err != nil {
msg.err <- err
return
}
// Create a goroutine to watch the chain so we can open the channel once
// the funding tx has enough confirmations.
go l.openChannelAfterConfirmations(pendingReservation)
msg.err <- nil
}
// handleSingleFunderSigs is called once the remote peer who initiated the
// single funder workflow has assembled the funding transaction, and generated
// a signature for our version of the commitment transaction. This method
// progresses the workflow by generating a signature for the remote peer's
// version of the commitment transaction.
func (l *LightningWallet) handleSingleFunderSigs(req *addSingleFunderSigsMsg) {
l.limboMtx.RLock()
pendingReservation, ok := l.fundingLimbo[req.pendingFundingID]
l.limboMtx.RUnlock()
if !ok {
req.err <- fmt.Errorf("attempted to update non-existant funding state")
return
}
// Grab the mutex on the ChannelReservation to ensure thead-safety
pendingReservation.Lock()
defer pendingReservation.Unlock()
pendingReservation.partialState.FundingOutpoint = req.fundingOutpoint
pendingReservation.partialState.TheirCurrentRevocation = req.revokeKey
pendingReservation.partialState.ChanID = req.fundingOutpoint
fundingTxIn := wire.NewTxIn(req.fundingOutpoint, nil, nil)
// Now that we have the funding outpoint, we can generate both versions
// of the commitment transaction, and generate a signature for the
// remote node's commitment transactions.
ourCommitKey := pendingReservation.ourContribution.CommitKey
theirCommitKey := pendingReservation.theirContribution.CommitKey
ourBalance := pendingReservation.ourContribution.FundingAmount
theirBalance := pendingReservation.theirContribution.FundingAmount
ourCommitTx, err := createCommitTx(fundingTxIn, ourCommitKey, theirCommitKey,
pendingReservation.ourContribution.RevocationKey,
pendingReservation.ourContribution.CsvDelay, ourBalance, theirBalance)
if err != nil {
req.err <- err
return
}
theirCommitTx, err := createCommitTx(fundingTxIn, theirCommitKey, ourCommitKey,
req.revokeKey, pendingReservation.theirContribution.CsvDelay,
theirBalance, ourBalance)
if err != nil {
req.err <- err
return
}
// Sort both transactions according to the agreed upon cannonical
// ordering. This ensures that both parties sign the same sighash
// without further synchronization.
txsort.InPlaceSort(ourCommitTx)
pendingReservation.partialState.OurCommitTx = ourCommitTx
txsort.InPlaceSort(theirCommitTx)
// Verify that their signature of valid for our current commitment
// transaction. Re-generate both the redeemScript and p2sh output. We
// sign the redeemScript script, but include the p2sh output as the
// subscript for verification.
// TODO(roasbeef): replace with regular sighash calculation once the PR
// is merged.
redeemScript := pendingReservation.partialState.FundingRedeemScript
p2wsh, err := witnessScriptHash(redeemScript)
if err != nil {
req.err <- err
return
}
// TODO(roasbeef): remove all duplication after merge.
// First, we sign our copy of the commitment transaction ourselves.
channelValue := int64(pendingReservation.partialState.Capacity)
hashCache := txscript.NewTxSigHashes(ourCommitTx)
theirKey := pendingReservation.theirContribution.MultiSigKey
ourKey := pendingReservation.partialState.OurMultiSigKey
ourCommitSig, err := txscript.RawTxInWitnessSignature(ourCommitTx, hashCache, 0,
channelValue, redeemScript, txscript.SigHashAll, ourKey)
if err != nil {
req.err <- err
return
}
// Next, create the spending scriptSig, and then verify that the script
// is complete, allowing us to spend from the funding transaction.
ourKeySer := ourKey.PubKey().SerializeCompressed()
theirKeySer := theirKey.SerializeCompressed()
witness := spendMultiSig(redeemScript, ourKeySer, ourCommitSig,
theirKeySer, req.theirCommitmentSig)
// Finally, create an instance of a Script VM, and ensure that the
// Script executes succesfully.
ourCommitTx.TxIn[0].Witness = witness
// TODO(roasbeef): replace engine with plain sighash check
vm, err := txscript.NewEngine(p2wsh,
ourCommitTx, 0, txscript.StandardVerifyFlags, nil,
nil, channelValue)
if err != nil {
req.err <- err
return
}
if err := vm.Execute(); err != nil {
req.err <- fmt.Errorf("counterparty's commitment signature is invalid: %v", err)
return
}
// Strip and store the signature to ensure that our commitment
// transaction doesn't stay hot.
ourCommitTx.TxIn[0].Witness = nil
pendingReservation.partialState.OurCommitSig = req.theirCommitmentSig
// With their signature for our version of the commitment transactions
// verified, we can now generate a signature for their version,
// allowing the funding transaction to be safely broadcast.
hashCache = txscript.NewTxSigHashes(theirCommitTx)
sigTheirCommit, err := txscript.RawTxInWitnessSignature(theirCommitTx, hashCache, 0,
channelValue, redeemScript, txscript.SigHashAll, ourKey)
if err != nil {
req.err <- err
return
}
pendingReservation.ourCommitmentSig = sigTheirCommit
req.err <- nil
}
// handleChannelOpen completes a single funder reservation to which we are the
// responder. This method saves the channel state to disk, finally "opening"
// the channel by sending it over to the caller of the reservation via the
// channel dispatch channel.
func (l *LightningWallet) handleChannelOpen(req *channelOpenMsg) {
l.limboMtx.RLock()
res, ok := l.fundingLimbo[req.pendingFundingID]
l.limboMtx.RUnlock()
if !ok {
req.err <- fmt.Errorf("attempted to update non-existant funding state")
res.chanOpen <- nil
return
}
// Grab the mutex on the ChannelReservation to ensure thead-safety
res.Lock()
defer res.Unlock()
// Funding complete, this entry can be removed from limbo.
l.limboMtx.Lock()
delete(l.fundingLimbo, res.reservationID)
l.limboMtx.Unlock()
// Add the complete funding transaction to the DB, in it's open bucket
// which will be used for the lifetime of this channel.
if err := res.partialState.FullSync(); err != nil {
req.err <- err
res.chanOpen <- nil
return
}
// Finally, create and officially open the payment channel!
// TODO(roasbeef): CreationTime once tx is 'open'
channel, _ := NewLightningChannel(l, l.ChainNotifier, l.channelDB,
res.partialState)
res.chanOpen <- channel
req.err <- nil
}
// openChannelAfterConfirmations creates, and opens a payment channel after
// the funding transaction created within the passed channel reservation
// obtains the specified number of confirmations.
func (l *LightningWallet) openChannelAfterConfirmations(res *ChannelReservation) {
// Register with the ChainNotifier for a notification once the funding
// transaction reaches `numConfs` confirmations.
txid := res.fundingTx.TxSha()
numConfs := uint32(res.numConfsToOpen)
confNtfn, _ := l.ChainNotifier.RegisterConfirmationsNtfn(&txid, numConfs)
log.Infof("Waiting for funding tx (txid: %v) to reach %v confirmations",
txid, numConfs)
// Wait until the specified number of confirmations has been reached,
// or the wallet signals a shutdown.
out:
select {
case _, ok := <-confNtfn.Confirmed:
// Reading a falsey value for the second parameter indicates that
// the notifier is in the process of shutting down. Therefore, we
// don't count this as the signal that the funding transaction has
// been confirmed.
if !ok {
res.chanOpen <- nil
return
}
break out
case <-l.quit:
res.chanOpen <- nil
return
}
// Finally, create and officially open the payment channel!
// TODO(roasbeef): CreationTime once tx is 'open'
channel, _ := NewLightningChannel(l, l.ChainNotifier, l.channelDB,
res.partialState)
res.chanOpen <- channel
}
2015-12-28 23:14:00 +03:00
// getNextRawKey retrieves the next key within our HD key-chain for use within
// as a multi-sig key within the funding transaction, or within the commitment
// transaction's outputs.
// TODO(roasbeef): on shutdown, write state of pending keys, then read back?
func (l *LightningWallet) getNextRawKey() (*btcec.PrivateKey, error) {
l.KeyGenMtx.Lock()
defer l.KeyGenMtx.Unlock()
nextAddr, err := l.Manager.NextExternalAddresses(waddrmgr.DefaultAccountNum,
1, waddrmgr.WitnessPubKey)
if err != nil {
return nil, err
}
pkAddr := nextAddr[0].(waddrmgr.ManagedPubKeyAddress)
return pkAddr.PrivKey()
}
// ListUnspentWitness returns a slice of all the unspent outputs the wallet
// controls which pay to witness programs either directly or indirectly.
func (l *LightningWallet) ListUnspentWitness(minConfs int32) ([]*btcjson.ListUnspentResult, error) {
// First, grab all the unfiltered currently unspent outputs.
maxConfs := int32(math.MaxInt32)
unspentOutputs, err := l.ListUnspent(minConfs, maxConfs, nil)
if err != nil {
return nil, err
}
// Next, we'll run through all the regular outputs, only saving those
// which are p2wkh outputs or a p2wsh output nested within a p2sh output.
witnessOutputs := make([]*btcjson.ListUnspentResult, 0, len(unspentOutputs))
for _, output := range unspentOutputs {
pkScript, err := hex.DecodeString(output.ScriptPubKey)
if err != nil {
return nil, err
}
// TODO(roasbeef): this assumes all p2sh outputs returned by
// the wallet are nested p2sh...
if txscript.IsPayToWitnessPubKeyHash(pkScript) ||
txscript.IsPayToScriptHash(pkScript) {
witnessOutputs = append(witnessOutputs, output)
}
}
return witnessOutputs, nil
}
// selectCoinsAndChange performs coin selection in order to obtain witness
// outputs which sum to at least 'numCoins' amount of satoshis. If coin
// selection is succesful/possible, then the selected coins are available within
// the passed contribution's inputs. If necessary, a change address will also be
// generated.
// TODO(roasbeef): remove hardcoded fees and req'd confs for outputs.
func (l *LightningWallet) selectCoinsAndChange(numCoins btcutil.Amount,
contribution *ChannelContribution) error {
// We hold the coin select mutex while querying for outputs, and
// performing coin selection in order to avoid inadvertent double spends
// accross funding transactions.
// NOTE: We don't use defer her so we can properly release the lock
// when we encounter an error condition.
l.coinSelectMtx.Lock()
// TODO(roasbeef): check if balance is insufficient, if so then select
// on two channels, one is a time.After that will bail out with
// insuffcient funds, the other is a notification that the balance has
// been updated make(chan struct{}, 1).
// Find all unlocked unspent witness outputs with greater than 1
// confirmation.
// TODO(roasbeef): make num confs a configuration paramter
unspentOutputs, err := l.ListUnspentWitness(1)
if err != nil {
l.coinSelectMtx.Unlock()
return err
}
// Convert the outputs to coins for coin selection below.
coins, err := outputsToCoins(unspentOutputs)
if err != nil {
l.coinSelectMtx.Unlock()
return err
}
// Peform coin selection over our available, unlocked unspent outputs
// in order to find enough coins to meet the funding amount requirements.
//
// TODO(roasbeef): Should extend coinset with optimal coin selection
// heuristics for our use case.
// NOTE: this current selection assumes "priority" is still a thing.
selector := &coinset.MaxValueAgeCoinSelector{
MaxInputs: 10,
MinChangeAmount: 10000,
}
// TODO(roasbeef): don't hardcode fee...
totalWithFee := numCoins + 10000
selectedCoins, err := selector.CoinSelect(totalWithFee, coins)
if err != nil {
l.coinSelectMtx.Unlock()
return err
}
// Lock the selected coins. These coins are now "reserved", this
// prevents concurrent funding requests from referring to and this
// double-spending the same set of coins.
contribution.Inputs = make([]*wire.TxIn, len(selectedCoins.Coins()))
for i, coin := range selectedCoins.Coins() {
txout := wire.NewOutPoint(coin.Hash(), coin.Index())
l.LockOutpoint(*txout)
// Empty sig script, we'll actually sign if this reservation is
// queued up to be completed (the other side accepts).
outPoint := wire.NewOutPoint(coin.Hash(), coin.Index())
contribution.Inputs[i] = wire.NewTxIn(outPoint, nil, nil)
}
l.coinSelectMtx.Unlock()
// Create some possibly neccessary change outputs.
selectedTotalValue := coinset.NewCoinSet(selectedCoins.Coins()).TotalValue()
if selectedTotalValue > totalWithFee {
// Change is necessary. Query for an available change address to
// send the remainder to.
contribution.ChangeOutputs = make([]*wire.TxOut, 1)
changeAddr, err := l.NewChangeAddress(waddrmgr.DefaultAccountNum,
waddrmgr.WitnessPubKey)
if err != nil {
return err
}
changeAddrScript, err := txscript.PayToAddrScript(changeAddr)
if err != nil {
return err
}
changeAmount := selectedTotalValue - totalWithFee
contribution.ChangeOutputs[0] = wire.NewTxOut(int64(changeAmount),
changeAddrScript)
}
// TODO(roasbeef): re-calculate fees here to minFeePerKB, may need more inputs
return nil
}
type WaddrmgrEncryptorDecryptor struct {
M *waddrmgr.Manager
}
func (w *WaddrmgrEncryptorDecryptor) Encrypt(p []byte) ([]byte, error) {
return w.M.Encrypt(waddrmgr.CKTPrivate, p)
}
func (w *WaddrmgrEncryptorDecryptor) Decrypt(c []byte) ([]byte, error) {
return w.M.Decrypt(waddrmgr.CKTPrivate, c)
}
func (w *WaddrmgrEncryptorDecryptor) OverheadSize() uint32 {
return 24
}