1447 lines
49 KiB
Go
1447 lines
49 KiB
Go
package lnwallet
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import (
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"bytes"
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"crypto/sha256"
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"fmt"
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"net"
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"sync"
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"sync/atomic"
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"github.com/davecgh/go-spew/spew"
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"github.com/lightningnetwork/lnd/channeldb"
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"github.com/lightningnetwork/lnd/keychain"
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"github.com/lightningnetwork/lnd/lnwire"
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"github.com/roasbeef/btcd/blockchain"
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"github.com/roasbeef/btcd/chaincfg/chainhash"
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"github.com/roasbeef/btcutil/hdkeychain"
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"github.com/lightningnetwork/lnd/shachain"
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"github.com/roasbeef/btcd/btcec"
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"github.com/roasbeef/btcd/txscript"
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"github.com/roasbeef/btcd/wire"
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"github.com/roasbeef/btcutil"
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"github.com/roasbeef/btcutil/txsort"
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)
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const (
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// The size of the buffered queue of requests to the wallet from the
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// outside word.
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msgBufferSize = 100
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)
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// ErrInsufficientFunds is a type matching the error interface which is
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// returned when coin selection for a new funding transaction fails to due
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// having an insufficient amount of confirmed funds.
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type ErrInsufficientFunds struct {
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amountAvailable btcutil.Amount
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amountSelected btcutil.Amount
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}
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func (e *ErrInsufficientFunds) Error() string {
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return fmt.Sprintf("not enough witness outputs to create funding transaction,"+
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" need %v only have %v available", e.amountAvailable,
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e.amountSelected)
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}
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// initFundingReserveReq is the first message sent to initiate the workflow
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// required to open a payment channel with a remote peer. The initial required
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// parameters are configurable across channels. These parameters are to be
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// chosen depending on the fee climate within the network, and time value of
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// funds to be locked up within the channel. Upon success a ChannelReservation
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// will be created in order to track the lifetime of this pending channel.
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// Outputs selected will be 'locked', making them unavailable, for any other
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// pending reservations. Therefore, all channels in reservation limbo will be
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// periodically timed out after an idle period in order to avoid "exhaustion"
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// attacks.
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type initFundingReserveMsg struct {
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// chainHash denotes that chain to be used to ultimately open the
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// target channel.
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chainHash *chainhash.Hash
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// nodeId is the ID of the remote node we would like to open a channel
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// with.
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nodeID *btcec.PublicKey
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// nodeAddr is the address port that we used to either establish or
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// accept the connection which led to the negotiation of this funding
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// workflow.
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nodeAddr net.Addr
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// fundingAmount is the amount of funds requested for this channel.
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fundingAmount btcutil.Amount
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// capacity is the total capacity of the channel which includes the
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// amount of funds the remote party contributes (if any).
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capacity btcutil.Amount
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// commitFeePerKw is the starting accepted satoshis/Kw fee for the set
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// of initial commitment transactions. In order to ensure timely
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// confirmation, it is recommended that this fee should be generous,
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// paying some multiple of the accepted base fee rate of the network.
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commitFeePerKw SatPerKWeight
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// fundingFeePerVSize is the fee rate in sat/vbyte to use for the
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// initial funding transaction.
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fundingFeePerVSize SatPerVByte
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// pushMSat is the number of milli-satoshis that should be pushed over
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// the responder as part of the initial channel creation.
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pushMSat lnwire.MilliSatoshi
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// flags are the channel flags specified by the initiator in the
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// open_channel message.
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flags lnwire.FundingFlag
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// err is a channel in which all errors will be sent across. Will be
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// nil if this initial set is successful.
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//
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// NOTE: In order to avoid deadlocks, this channel MUST be buffered.
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err chan error
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// resp is channel in which a ChannelReservation with our contributions
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// filled in will be sent across this channel in the case of a
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// successfully reservation initiation. In the case of an error, this
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// will read a nil pointer.
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//
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// NOTE: In order to avoid deadlocks, this channel MUST be buffered.
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resp chan *ChannelReservation
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}
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// fundingReserveCancelMsg is a message reserved for cancelling an existing
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// channel reservation identified by its reservation ID. Cancelling a reservation
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// frees its locked outputs up, for inclusion within further reservations.
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type fundingReserveCancelMsg struct {
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pendingFundingID uint64
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// NOTE: In order to avoid deadlocks, this channel MUST be buffered.
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err chan error // Buffered
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}
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// addContributionMsg represents a message executing the second phase of the
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// channel reservation workflow. This message carries the counterparty's
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// "contribution" to the payment channel. In the case that this message is
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// processed without generating any errors, then channel reservation will then
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// be able to construct the funding tx, both commitment transactions, and
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// finally generate signatures for all our inputs to the funding transaction,
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// and for the remote node's version of the commitment transaction.
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type addContributionMsg struct {
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pendingFundingID uint64
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// TODO(roasbeef): Should also carry SPV proofs in we're in SPV mode
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contribution *ChannelContribution
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// NOTE: In order to avoid deadlocks, this channel MUST be buffered.
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err chan error
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}
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// addSingleContributionMsg represents a message executing the second phase of
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// a single funder channel reservation workflow. This messages carries the
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// counterparty's "contribution" to the payment channel. As this message is
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// sent when on the responding side to a single funder workflow, no further
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// action apart from storing the provided contribution is carried out.
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type addSingleContributionMsg struct {
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pendingFundingID uint64
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contribution *ChannelContribution
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// NOTE: In order to avoid deadlocks, this channel MUST be buffered.
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err chan error
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}
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// addCounterPartySigsMsg represents the final message required to complete,
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// and 'open' a payment channel. This message carries the counterparty's
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// signatures for each of their inputs to the funding transaction, and also a
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// signature allowing us to spend our version of the commitment transaction.
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// If we're able to verify all the signatures are valid, the funding transaction
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// will be broadcast to the network. After the funding transaction gains a
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// configurable number of confirmations, the channel is officially considered
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// 'open'.
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type addCounterPartySigsMsg struct {
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pendingFundingID uint64
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// Should be order of sorted inputs that are theirs. Sorting is done
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// in accordance to BIP-69:
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// https://github.com/bitcoin/bips/blob/master/bip-0069.mediawiki.
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theirFundingInputScripts []*InputScript
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// This should be 1/2 of the signatures needed to successfully spend our
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// version of the commitment transaction.
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theirCommitmentSig []byte
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// This channel is used to return the completed channel after the wallet
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// has completed all of its stages in the funding process.
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completeChan chan *channeldb.OpenChannel
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// NOTE: In order to avoid deadlocks, this channel MUST be buffered.
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err chan error
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}
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// addSingleFunderSigsMsg represents the next-to-last message required to
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// complete a single-funder channel workflow. Once the initiator is able to
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// construct the funding transaction, they send both the outpoint and a
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// signature for our version of the commitment transaction. Once this message
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// is processed we (the responder) are able to construct both commitment
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// transactions, signing the remote party's version.
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type addSingleFunderSigsMsg struct {
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pendingFundingID uint64
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// fundingOutpoint is the outpoint of the completed funding
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// transaction as assembled by the workflow initiator.
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fundingOutpoint *wire.OutPoint
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// theirCommitmentSig are the 1/2 of the signatures needed to
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// successfully spend our version of the commitment transaction.
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theirCommitmentSig []byte
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// This channel is used to return the completed channel after the wallet
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// has completed all of its stages in the funding process.
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completeChan chan *channeldb.OpenChannel
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// NOTE: In order to avoid deadlocks, this channel MUST be buffered.
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err chan error
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}
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// LightningWallet is a domain specific, yet general Bitcoin wallet capable of
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// executing workflow required to interact with the Lightning Network. It is
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// domain specific in the sense that it understands all the fancy scripts used
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// within the Lightning Network, channel lifetimes, etc. However, it embeds a
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// general purpose Bitcoin wallet within it. Therefore, it is also able to
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// serve as a regular Bitcoin wallet which uses HD keys. The wallet is highly
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// concurrent internally. All communication, and requests towards the wallet
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// are dispatched as messages over channels, ensuring thread safety across all
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// operations. Interaction has been designed independent of any peer-to-peer
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// communication protocol, allowing the wallet to be self-contained and
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// embeddable within future projects interacting with the Lightning Network.
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//
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// NOTE: At the moment the wallet requires a btcd full node, as it's dependent
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// on btcd's websockets notifications as event triggers during the lifetime of a
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// channel. However, once the chainntnfs package is complete, the wallet will
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// be compatible with multiple RPC/notification services such as Electrum,
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// Bitcoin Core + ZeroMQ, etc. Eventually, the wallet won't require a full-node
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// at all, as SPV support is integrated into btcwallet.
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type LightningWallet struct {
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started int32 // To be used atomically.
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shutdown int32 // To be used atomically.
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nextFundingID uint64 // To be used atomically.
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// Cfg is the configuration struct that will be used by the wallet to
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// access the necessary interfaces and default it needs to carry on its
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// duties.
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Cfg Config
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// WalletController is the core wallet, all non Lightning Network
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// specific interaction is proxied to the internal wallet.
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WalletController
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// SecretKeyRing is the interface we'll use to derive any keys related
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// to our purpose within the network including: multi-sig keys, node
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// keys, revocation keys, etc.
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keychain.SecretKeyRing
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// This mutex is to be held when generating external keys to be used as
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// multi-sig, and commitment keys within the channel.
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keyGenMtx sync.RWMutex
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// This mutex MUST be held when performing coin selection in order to
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// avoid inadvertently creating multiple funding transaction which
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// double spend inputs across each other.
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coinSelectMtx sync.RWMutex
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// rootKey is the root HD key derived from a WalletController private
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// key. This rootKey is used to derive all LN specific secrets.
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rootKey *hdkeychain.ExtendedKey
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// All messages to the wallet are to be sent across this channel.
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msgChan chan interface{}
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// Incomplete payment channels are stored in the map below. An intent
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// to create a payment channel is tracked as a "reservation" within
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// limbo. Once the final signatures have been exchanged, a reservation
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// is removed from limbo. Each reservation is tracked by a unique
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// monotonically integer. All requests concerning the channel MUST
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// carry a valid, active funding ID.
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fundingLimbo map[uint64]*ChannelReservation
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limboMtx sync.RWMutex
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// lockedOutPoints is a set of the currently locked outpoint. This
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// information is kept in order to provide an easy way to unlock all
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// the currently locked outpoints.
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lockedOutPoints map[wire.OutPoint]struct{}
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quit chan struct{}
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wg sync.WaitGroup
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// TODO(roasbeef): handle wallet lock/unlock
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}
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// NewLightningWallet creates/opens and initializes a LightningWallet instance.
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// If the wallet has never been created (according to the passed dataDir), first-time
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// setup is executed.
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func NewLightningWallet(Cfg Config) (*LightningWallet, error) {
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return &LightningWallet{
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Cfg: Cfg,
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SecretKeyRing: Cfg.SecretKeyRing,
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WalletController: Cfg.WalletController,
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msgChan: make(chan interface{}, msgBufferSize),
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nextFundingID: 0,
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fundingLimbo: make(map[uint64]*ChannelReservation),
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lockedOutPoints: make(map[wire.OutPoint]struct{}),
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quit: make(chan struct{}),
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}, nil
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}
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// Startup establishes a connection to the RPC source, and spins up all
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// goroutines required to handle incoming messages.
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func (l *LightningWallet) Startup() error {
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// Already started?
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if atomic.AddInt32(&l.started, 1) != 1 {
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return nil
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}
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// Start the underlying wallet controller.
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if err := l.Start(); err != nil {
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return err
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}
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l.wg.Add(1)
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// TODO(roasbeef): multiple request handlers?
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go l.requestHandler()
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return nil
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}
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// Shutdown gracefully stops the wallet, and all active goroutines.
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func (l *LightningWallet) Shutdown() error {
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if atomic.AddInt32(&l.shutdown, 1) != 1 {
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return nil
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}
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// Signal the underlying wallet controller to shutdown, waiting until
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// all active goroutines have been shutdown.
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if err := l.Stop(); err != nil {
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return err
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}
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close(l.quit)
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l.wg.Wait()
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return nil
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}
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// LockedOutpoints returns a list of all currently locked outpoint.
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func (l *LightningWallet) LockedOutpoints() []*wire.OutPoint {
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outPoints := make([]*wire.OutPoint, 0, len(l.lockedOutPoints))
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for outPoint := range l.lockedOutPoints {
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outPoints = append(outPoints, &outPoint)
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}
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return outPoints
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}
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// ResetReservations reset the volatile wallet state which tracks all currently
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// active reservations.
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func (l *LightningWallet) ResetReservations() {
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l.nextFundingID = 0
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l.fundingLimbo = make(map[uint64]*ChannelReservation)
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for outpoint := range l.lockedOutPoints {
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l.UnlockOutpoint(outpoint)
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}
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l.lockedOutPoints = make(map[wire.OutPoint]struct{})
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}
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// ActiveReservations returns a slice of all the currently active
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// (non-cancelled) reservations.
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func (l *LightningWallet) ActiveReservations() []*ChannelReservation {
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reservations := make([]*ChannelReservation, 0, len(l.fundingLimbo))
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for _, reservation := range l.fundingLimbo {
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reservations = append(reservations, reservation)
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}
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return reservations
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}
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// requestHandler is the primary goroutine(s) responsible for handling, and
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// dispatching replies to all messages.
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func (l *LightningWallet) requestHandler() {
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out:
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for {
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select {
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case m := <-l.msgChan:
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switch msg := m.(type) {
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case *initFundingReserveMsg:
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l.handleFundingReserveRequest(msg)
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case *fundingReserveCancelMsg:
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l.handleFundingCancelRequest(msg)
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case *addSingleContributionMsg:
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l.handleSingleContribution(msg)
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case *addContributionMsg:
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l.handleContributionMsg(msg)
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case *addSingleFunderSigsMsg:
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l.handleSingleFunderSigs(msg)
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case *addCounterPartySigsMsg:
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l.handleFundingCounterPartySigs(msg)
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}
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case <-l.quit:
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// TODO: do some clean up
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break out
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}
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}
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l.wg.Done()
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}
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|
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// InitChannelReservation kicks off the 3-step workflow required to successfully
|
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// open a payment channel with a remote node. As part of the funding
|
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// reservation, the inputs selected for the funding transaction are 'locked'.
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// This ensures that multiple channel reservations aren't double spending the
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// same inputs in the funding transaction. If reservation initialization is
|
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// successful, a ChannelReservation containing our completed contribution is
|
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// returned. Our contribution contains all the items necessary to allow the
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// counterparty to build the funding transaction, and both versions of the
|
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// commitment transaction. Otherwise, an error occurred and a nil pointer along
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// with an error are returned.
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//
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// Once a ChannelReservation has been obtained, two additional steps must be
|
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// processed before a payment channel can be considered 'open'. The second step
|
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// validates, and processes the counterparty's channel contribution. The third,
|
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// and final step verifies all signatures for the inputs of the funding
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// transaction, and that the signature we record for our version of the
|
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// commitment transaction is valid.
|
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func (l *LightningWallet) InitChannelReservation(
|
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capacity, ourFundAmt btcutil.Amount, pushMSat lnwire.MilliSatoshi,
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commitFeePerKw SatPerKWeight, fundingFeePerVSize SatPerVByte,
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theirID *btcec.PublicKey, theirAddr net.Addr,
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chainHash *chainhash.Hash, flags lnwire.FundingFlag) (*ChannelReservation, error) {
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errChan := make(chan error, 1)
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respChan := make(chan *ChannelReservation, 1)
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|
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l.msgChan <- &initFundingReserveMsg{
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chainHash: chainHash,
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nodeID: theirID,
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nodeAddr: theirAddr,
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fundingAmount: ourFundAmt,
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capacity: capacity,
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commitFeePerKw: commitFeePerKw,
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fundingFeePerVSize: fundingFeePerVSize,
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pushMSat: pushMSat,
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flags: flags,
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err: errChan,
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resp: respChan,
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}
|
|
|
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return <-respChan, <-errChan
|
|
}
|
|
|
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// handleFundingReserveRequest processes a message intending to create, and
|
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// validate a funding reservation request.
|
|
func (l *LightningWallet) handleFundingReserveRequest(req *initFundingReserveMsg) {
|
|
// It isn't possible to create a channel with zero funds committed.
|
|
if req.fundingAmount+req.capacity == 0 {
|
|
err := ErrZeroCapacity()
|
|
req.err <- err
|
|
req.resp <- nil
|
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return
|
|
}
|
|
|
|
// If the funding request is for a different chain than the one the
|
|
// wallet is aware of, then we'll reject the request.
|
|
if !bytes.Equal(l.Cfg.NetParams.GenesisHash[:], req.chainHash[:]) {
|
|
err := ErrChainMismatch(l.Cfg.NetParams.GenesisHash,
|
|
req.chainHash)
|
|
req.err <- err
|
|
req.resp <- nil
|
|
return
|
|
}
|
|
|
|
id := atomic.AddUint64(&l.nextFundingID, 1)
|
|
reservation, err := NewChannelReservation(req.capacity, req.fundingAmount,
|
|
req.commitFeePerKw, l, id, req.pushMSat,
|
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l.Cfg.NetParams.GenesisHash, req.flags)
|
|
if err != nil {
|
|
req.err <- err
|
|
req.resp <- nil
|
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return
|
|
}
|
|
|
|
// Grab the mutex on the ChannelReservation to ensure thread-safety
|
|
reservation.Lock()
|
|
defer reservation.Unlock()
|
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|
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reservation.nodeAddr = req.nodeAddr
|
|
reservation.partialState.IdentityPub = req.nodeID
|
|
|
|
// 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 {
|
|
// Coin selection is done on the basis of sat-per-vbyte, we'll
|
|
// use the passed sat/vbyte passed in to perform coin selection.
|
|
err := l.selectCoinsAndChange(
|
|
req.fundingFeePerVSize, req.fundingAmount,
|
|
reservation.ourContribution,
|
|
)
|
|
if err != nil {
|
|
req.err <- err
|
|
req.resp <- nil
|
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return
|
|
}
|
|
}
|
|
|
|
// Next, we'll grab a series of keys from the wallet which will be used
|
|
// for the duration of the channel. The keys include: our multi-sig
|
|
// key, the base revocation key, the base htlc key,the base payment
|
|
// key, and the delayed payment key.
|
|
//
|
|
// TODO(roasbeef): "salt" each key as well?
|
|
reservation.ourContribution.MultiSigKey, err = l.DeriveNextKey(
|
|
keychain.KeyFamilyMultiSig,
|
|
)
|
|
if err != nil {
|
|
req.err <- err
|
|
req.resp <- nil
|
|
return
|
|
}
|
|
reservation.ourContribution.RevocationBasePoint, err = l.DeriveNextKey(
|
|
keychain.KeyFamilyRevocationBase,
|
|
)
|
|
if err != nil {
|
|
req.err <- err
|
|
req.resp <- nil
|
|
return
|
|
}
|
|
reservation.ourContribution.HtlcBasePoint, err = l.DeriveNextKey(
|
|
keychain.KeyFamilyHtlcBase,
|
|
)
|
|
if err != nil {
|
|
req.err <- err
|
|
req.resp <- nil
|
|
return
|
|
}
|
|
reservation.ourContribution.PaymentBasePoint, err = l.DeriveNextKey(
|
|
keychain.KeyFamilyPaymentBase,
|
|
)
|
|
if err != nil {
|
|
req.err <- err
|
|
req.resp <- nil
|
|
return
|
|
}
|
|
reservation.ourContribution.DelayBasePoint, err = l.DeriveNextKey(
|
|
keychain.KeyFamilyDelayBase,
|
|
)
|
|
if err != nil {
|
|
req.err <- err
|
|
req.resp <- nil
|
|
return
|
|
}
|
|
|
|
// With the above keys created, we'll also need to initialization our
|
|
// initial revocation tree state.
|
|
nextRevocationKeyDesc, err := l.DeriveNextKey(
|
|
keychain.KeyFamilyRevocationRoot,
|
|
)
|
|
if err != nil {
|
|
req.err <- err
|
|
req.resp <- nil
|
|
return
|
|
}
|
|
revocationRoot, err := l.DerivePrivKey(nextRevocationKeyDesc)
|
|
if err != nil {
|
|
req.err <- err
|
|
req.resp <- nil
|
|
return
|
|
}
|
|
|
|
// Once we have the root, we can then generate our shachain producer
|
|
// and from that generate the per-commitment point.
|
|
revRoot, err := chainhash.NewHash(revocationRoot.Serialize())
|
|
if err != nil {
|
|
req.err <- err
|
|
req.resp <- nil
|
|
return
|
|
}
|
|
producer := shachain.NewRevocationProducer(*revRoot)
|
|
firstPreimage, err := producer.AtIndex(0)
|
|
if err != nil {
|
|
req.err <- err
|
|
req.resp <- nil
|
|
return
|
|
}
|
|
reservation.ourContribution.FirstCommitmentPoint = ComputeCommitmentPoint(
|
|
firstPreimage[:],
|
|
)
|
|
|
|
reservation.partialState.RevocationProducer = producer
|
|
reservation.ourContribution.ChannelConstraints = l.Cfg.DefaultConstraints
|
|
|
|
// TODO(roasbeef): turn above into: initContribution()
|
|
|
|
// Create a limbo and record entry for this newly pending funding
|
|
// request.
|
|
l.limboMtx.Lock()
|
|
l.fundingLimbo[id] = reservation
|
|
l.limboMtx.Unlock()
|
|
|
|
// Funding reservation request successfully handled. The funding inputs
|
|
// will be marked as unavailable until the reservation is either
|
|
// completed, or cancelled.
|
|
req.resp <- reservation
|
|
req.err <- nil
|
|
}
|
|
|
|
// 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, "unknown funding state" or something
|
|
req.err <- fmt.Errorf("attempted to cancel non-existent funding state")
|
|
return
|
|
}
|
|
|
|
// Grab the mutex on the ChannelReservation to ensure thread-safety
|
|
pendingReservation.Lock()
|
|
defer pendingReservation.Unlock()
|
|
|
|
// Mark all previously locked outpoints as useable for future funding
|
|
// requests.
|
|
for _, unusedInput := range pendingReservation.ourContribution.Inputs {
|
|
delete(l.lockedOutPoints, unusedInput.PreviousOutPoint)
|
|
l.UnlockOutpoint(unusedInput.PreviousOutPoint)
|
|
}
|
|
|
|
// TODO(roasbeef): is it even worth it to keep track of unused keys?
|
|
|
|
// TODO(roasbeef): Is it possible to mark the unused change also as
|
|
// available?
|
|
|
|
delete(l.fundingLimbo, req.pendingFundingID)
|
|
|
|
req.err <- nil
|
|
}
|
|
|
|
// CreateCommitmentTxns is a helper function that creates the initial
|
|
// commitment transaction for both parties. This function is used during the
|
|
// initial funding workflow as both sides must generate a signature for the
|
|
// remote party's commitment transaction, and verify the signature for their
|
|
// version of the commitment transaction.
|
|
func CreateCommitmentTxns(localBalance, remoteBalance btcutil.Amount,
|
|
ourChanCfg, theirChanCfg *channeldb.ChannelConfig,
|
|
localCommitPoint, remoteCommitPoint *btcec.PublicKey,
|
|
fundingTxIn wire.TxIn) (*wire.MsgTx, *wire.MsgTx, error) {
|
|
|
|
localCommitmentKeys := deriveCommitmentKeys(localCommitPoint, true,
|
|
ourChanCfg, theirChanCfg)
|
|
remoteCommitmentKeys := deriveCommitmentKeys(remoteCommitPoint, false,
|
|
ourChanCfg, theirChanCfg)
|
|
|
|
ourCommitTx, err := CreateCommitTx(fundingTxIn, localCommitmentKeys,
|
|
uint32(ourChanCfg.CsvDelay), localBalance, remoteBalance,
|
|
ourChanCfg.DustLimit)
|
|
if err != nil {
|
|
return nil, nil, err
|
|
}
|
|
|
|
otxn := btcutil.NewTx(ourCommitTx)
|
|
if err := blockchain.CheckTransactionSanity(otxn); err != nil {
|
|
return nil, nil, err
|
|
}
|
|
|
|
theirCommitTx, err := CreateCommitTx(fundingTxIn, remoteCommitmentKeys,
|
|
uint32(theirChanCfg.CsvDelay), remoteBalance, localBalance,
|
|
theirChanCfg.DustLimit)
|
|
if err != nil {
|
|
return nil, nil, err
|
|
}
|
|
|
|
ttxn := btcutil.NewTx(theirCommitTx)
|
|
if err := blockchain.CheckTransactionSanity(ttxn); err != nil {
|
|
return nil, nil, err
|
|
}
|
|
|
|
return ourCommitTx, theirCommitTx, nil
|
|
}
|
|
|
|
// handleContributionMsg 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-existent funding state")
|
|
return
|
|
}
|
|
|
|
// Grab the mutex on the ChannelReservation to ensure thread-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(1)
|
|
fundingTx := pendingReservation.fundingTx
|
|
|
|
// 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.ourContribution.MultiSigKey
|
|
theirKey := theirContribution.MultiSigKey
|
|
|
|
// Finally, add the 2-of-2 multi-sig output which will set up the lightning
|
|
// channel.
|
|
channelCapacity := int64(pendingReservation.partialState.Capacity)
|
|
witnessScript, multiSigOut, err := GenFundingPkScript(
|
|
ourKey.PubKey.SerializeCompressed(),
|
|
theirKey.PubKey.SerializeCompressed(), channelCapacity,
|
|
)
|
|
if err != nil {
|
|
req.err <- err
|
|
return
|
|
}
|
|
|
|
// Sort the transaction. Since both side agree to a canonical ordering,
|
|
// by sorting we no longer need to send the entire transaction. Only
|
|
// signatures will be exchanged.
|
|
fundingTx.AddTxOut(multiSigOut)
|
|
txsort.InPlaceSort(pendingReservation.fundingTx)
|
|
|
|
// Next, sign all inputs that are ours, collecting the signatures in
|
|
// order of the inputs.
|
|
pendingReservation.ourFundingInputScripts = make([]*InputScript, 0,
|
|
len(ourContribution.Inputs))
|
|
signDesc := SignDescriptor{
|
|
HashType: txscript.SigHashAll,
|
|
SigHashes: txscript.NewTxSigHashes(fundingTx),
|
|
}
|
|
for i, txIn := range fundingTx.TxIn {
|
|
info, err := l.FetchInputInfo(&txIn.PreviousOutPoint)
|
|
if err == ErrNotMine {
|
|
continue
|
|
} else if err != nil {
|
|
req.err <- err
|
|
return
|
|
}
|
|
|
|
signDesc.Output = info
|
|
signDesc.InputIndex = i
|
|
|
|
inputScript, err := l.Cfg.Signer.ComputeInputScript(fundingTx,
|
|
&signDesc)
|
|
if err != nil {
|
|
req.err <- err
|
|
return
|
|
}
|
|
|
|
txIn.SignatureScript = inputScript.ScriptSig
|
|
txIn.Witness = inputScript.Witness
|
|
pendingReservation.ourFundingInputScripts = append(
|
|
pendingReservation.ourFundingInputScripts,
|
|
inputScript,
|
|
)
|
|
}
|
|
|
|
// Locate the index of the multi-sig outpoint in order to record it
|
|
// since the outputs are canonically sorted. If this is a single funder
|
|
// workflow, then we'll also need to send this to the remote node.
|
|
fundingTxID := fundingTx.TxHash()
|
|
_, multiSigIndex := FindScriptOutputIndex(fundingTx, multiSigOut.PkScript)
|
|
fundingOutpoint := wire.NewOutPoint(&fundingTxID, multiSigIndex)
|
|
pendingReservation.partialState.FundingOutpoint = *fundingOutpoint
|
|
|
|
walletLog.Debugf("Funding tx for ChannelPoint(%v) generated: %v",
|
|
fundingOutpoint, spew.Sdump(fundingTx))
|
|
|
|
// Initialize an empty sha-chain for them, tracking the current pending
|
|
// revocation hash (we don't yet know the preimage so we can't add it
|
|
// to the chain).
|
|
s := shachain.NewRevocationStore()
|
|
pendingReservation.partialState.RevocationStore = s
|
|
|
|
// Store their current commitment point. We'll need this after the
|
|
// first state transition in order to verify the authenticity of the
|
|
// revocation.
|
|
chanState := pendingReservation.partialState
|
|
chanState.RemoteCurrentRevocation = theirContribution.FirstCommitmentPoint
|
|
|
|
// Create the txin to our commitment transaction; required to construct
|
|
// the commitment transactions.
|
|
fundingTxIn := wire.TxIn{
|
|
PreviousOutPoint: wire.OutPoint{
|
|
Hash: fundingTxID,
|
|
Index: multiSigIndex,
|
|
},
|
|
}
|
|
|
|
// With the funding tx complete, create both commitment transactions.
|
|
localBalance := pendingReservation.partialState.LocalCommitment.LocalBalance.ToSatoshis()
|
|
remoteBalance := pendingReservation.partialState.LocalCommitment.RemoteBalance.ToSatoshis()
|
|
ourCommitTx, theirCommitTx, err := CreateCommitmentTxns(
|
|
localBalance, remoteBalance, ourContribution.ChannelConfig,
|
|
theirContribution.ChannelConfig,
|
|
ourContribution.FirstCommitmentPoint,
|
|
theirContribution.FirstCommitmentPoint, fundingTxIn,
|
|
)
|
|
if err != nil {
|
|
req.err <- err
|
|
return
|
|
}
|
|
|
|
// With both commitment transactions constructed, generate the state
|
|
// obfuscator then use it to encode the current state number within
|
|
// both commitment transactions.
|
|
var stateObfuscator [StateHintSize]byte
|
|
if chanState.ChanType == channeldb.SingleFunder {
|
|
stateObfuscator = DeriveStateHintObfuscator(
|
|
ourContribution.PaymentBasePoint.PubKey,
|
|
theirContribution.PaymentBasePoint.PubKey,
|
|
)
|
|
} else {
|
|
ourSer := ourContribution.PaymentBasePoint.PubKey.SerializeCompressed()
|
|
theirSer := theirContribution.PaymentBasePoint.PubKey.SerializeCompressed()
|
|
switch bytes.Compare(ourSer, theirSer) {
|
|
case -1:
|
|
stateObfuscator = DeriveStateHintObfuscator(
|
|
ourContribution.PaymentBasePoint.PubKey,
|
|
theirContribution.PaymentBasePoint.PubKey,
|
|
)
|
|
default:
|
|
stateObfuscator = DeriveStateHintObfuscator(
|
|
theirContribution.PaymentBasePoint.PubKey,
|
|
ourContribution.PaymentBasePoint.PubKey,
|
|
)
|
|
}
|
|
}
|
|
err = initStateHints(ourCommitTx, theirCommitTx, stateObfuscator)
|
|
if err != nil {
|
|
req.err <- err
|
|
return
|
|
}
|
|
|
|
// Sort both transactions according to the agreed upon canonical
|
|
// ordering. This lets us skip sending the entire transaction over,
|
|
// instead we'll just send signatures.
|
|
txsort.InPlaceSort(ourCommitTx)
|
|
txsort.InPlaceSort(theirCommitTx)
|
|
|
|
walletLog.Debugf("Local commit tx for ChannelPoint(%v): %v",
|
|
fundingOutpoint, spew.Sdump(ourCommitTx))
|
|
walletLog.Debugf("Remote commit tx for ChannelPoint(%v): %v",
|
|
fundingOutpoint, spew.Sdump(theirCommitTx))
|
|
|
|
// Record newly available information within the open channel state.
|
|
chanState.FundingOutpoint = *fundingOutpoint
|
|
chanState.LocalCommitment.CommitTx = ourCommitTx
|
|
chanState.RemoteCommitment.CommitTx = theirCommitTx
|
|
|
|
// Generate a signature for their version of the initial commitment
|
|
// transaction.
|
|
signDesc = SignDescriptor{
|
|
WitnessScript: witnessScript,
|
|
KeyDesc: ourKey,
|
|
Output: multiSigOut,
|
|
HashType: txscript.SigHashAll,
|
|
SigHashes: txscript.NewTxSigHashes(theirCommitTx),
|
|
InputIndex: 0,
|
|
}
|
|
sigTheirCommit, err := l.Cfg.Signer.SignOutputRaw(theirCommitTx, &signDesc)
|
|
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-existent funding state")
|
|
return
|
|
}
|
|
|
|
// Grab the mutex on the channelReservation to ensure thread-safety.
|
|
pendingReservation.Lock()
|
|
defer pendingReservation.Unlock()
|
|
|
|
// TODO(roasbeef): verify sanity of remote party's parameters, fail if
|
|
// disagree
|
|
|
|
// 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
|
|
chanState := pendingReservation.partialState
|
|
|
|
// Initialize an empty sha-chain for them, tracking the current pending
|
|
// revocation hash (we don't yet know the preimage so we can't add it
|
|
// to the chain).
|
|
remotePreimageStore := shachain.NewRevocationStore()
|
|
chanState.RevocationStore = remotePreimageStore
|
|
|
|
// Now that we've received their first commitment point, we'll store it
|
|
// within the channel state so we can sync it to disk once the funding
|
|
// process is complete.
|
|
chanState.RemoteCurrentRevocation = theirContribution.FirstCommitmentPoint
|
|
|
|
req.err <- nil
|
|
return
|
|
}
|
|
|
|
// openChanDetails contains a "finalized" channel which can be considered
|
|
// "open" according to the requested confirmation depth at reservation
|
|
// initialization. Additionally, the struct contains additional details
|
|
// pertaining to the exact location in the main chain in-which the transaction
|
|
// was confirmed.
|
|
type openChanDetails struct {
|
|
channel *LightningChannel
|
|
blockHeight uint32
|
|
txIndex uint32
|
|
}
|
|
|
|
// handleFundingCounterPartySigs is the final step in the channel reservation
|
|
// workflow. During this step, 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()
|
|
res, ok := l.fundingLimbo[msg.pendingFundingID]
|
|
l.limboMtx.RUnlock()
|
|
if !ok {
|
|
msg.err <- fmt.Errorf("attempted to update non-existent funding state")
|
|
return
|
|
}
|
|
|
|
// Grab the mutex on the ChannelReservation to ensure thread-safety
|
|
res.Lock()
|
|
defer res.Unlock()
|
|
|
|
// Now we can complete the funding transaction by adding their
|
|
// signatures to their inputs.
|
|
res.theirFundingInputScripts = msg.theirFundingInputScripts
|
|
inputScripts := msg.theirFundingInputScripts
|
|
fundingTx := res.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.
|
|
// TODO(roasbeef): when dual funder pass actual height-hint
|
|
output, err := l.Cfg.ChainIO.GetUtxo(&txin.PreviousOutPoint, 0)
|
|
if output == nil {
|
|
msg.err <- fmt.Errorf("input to funding tx "+
|
|
"does not exist: %v", err)
|
|
msg.completeChan <- nil
|
|
return
|
|
}
|
|
|
|
// Ensure that the witness+sigScript combo is valid.
|
|
vm, err := txscript.NewEngine(output.PkScript,
|
|
fundingTx, i, txscript.StandardVerifyFlags, nil,
|
|
fundingHashCache, output.Value)
|
|
if err != nil {
|
|
msg.err <- fmt.Errorf("cannot create script "+
|
|
"engine: %s", err)
|
|
msg.completeChan <- nil
|
|
return
|
|
}
|
|
if err = vm.Execute(); err != nil {
|
|
msg.err <- fmt.Errorf("cannot validate "+
|
|
"transaction: %s", err)
|
|
msg.completeChan <- nil
|
|
return
|
|
}
|
|
|
|
sigIndex++
|
|
}
|
|
}
|
|
|
|
// At this point, we can also record and verify their signature for our
|
|
// commitment transaction.
|
|
res.theirCommitmentSig = msg.theirCommitmentSig
|
|
commitTx := res.partialState.LocalCommitment.CommitTx
|
|
ourKey := res.ourContribution.MultiSigKey
|
|
theirKey := res.theirContribution.MultiSigKey
|
|
|
|
// Re-generate both the witnessScript and p2sh output. We sign the
|
|
// witnessScript script, but include the p2sh output as the subscript
|
|
// for verification.
|
|
witnessScript, _, err := GenFundingPkScript(
|
|
ourKey.PubKey.SerializeCompressed(),
|
|
theirKey.PubKey.SerializeCompressed(),
|
|
int64(res.partialState.Capacity),
|
|
)
|
|
if err != nil {
|
|
msg.err <- err
|
|
msg.completeChan <- nil
|
|
return
|
|
}
|
|
|
|
// Next, create the spending scriptSig, and then verify that the script
|
|
// is complete, allowing us to spend from the funding transaction.
|
|
channelValue := int64(res.partialState.Capacity)
|
|
hashCache := txscript.NewTxSigHashes(commitTx)
|
|
sigHash, err := txscript.CalcWitnessSigHash(witnessScript, hashCache,
|
|
txscript.SigHashAll, commitTx, 0, channelValue)
|
|
if err != nil {
|
|
msg.err <- err
|
|
msg.completeChan <- nil
|
|
return
|
|
}
|
|
|
|
// Verify that we've received a valid signature from the remote party
|
|
// for our version of the commitment transaction.
|
|
theirCommitSig := msg.theirCommitmentSig
|
|
sig, err := btcec.ParseSignature(theirCommitSig, btcec.S256())
|
|
if err != nil {
|
|
msg.err <- err
|
|
msg.completeChan <- nil
|
|
return
|
|
} else if !sig.Verify(sigHash, theirKey.PubKey) {
|
|
msg.err <- fmt.Errorf("counterparty's commitment signature is invalid")
|
|
msg.completeChan <- nil
|
|
return
|
|
}
|
|
res.partialState.LocalCommitment.CommitSig = theirCommitSig
|
|
|
|
// Funding complete, this entry can be removed from limbo.
|
|
l.limboMtx.Lock()
|
|
delete(l.fundingLimbo, res.reservationID)
|
|
l.limboMtx.Unlock()
|
|
|
|
// As we're about to broadcast the funding transaction, we'll take note
|
|
// of the current height for record keeping purposes.
|
|
//
|
|
// TODO(roasbeef): this info can also be piped into light client's
|
|
// basic fee estimation?
|
|
_, bestHeight, err := l.Cfg.ChainIO.GetBestBlock()
|
|
if err != nil {
|
|
msg.err <- err
|
|
msg.completeChan <- nil
|
|
return
|
|
}
|
|
|
|
// As we've completed the funding process, we'll no convert the
|
|
// contribution structs into their underlying channel config objects to
|
|
// he stored within the database.
|
|
res.partialState.LocalChanCfg = res.ourContribution.toChanConfig()
|
|
res.partialState.RemoteChanCfg = res.theirContribution.toChanConfig()
|
|
|
|
// We'll also record the finalized funding txn, which will allow us to
|
|
// rebroadcast on startup in case we fail.
|
|
res.partialState.FundingTxn = fundingTx
|
|
|
|
// Add the complete funding transaction to the DB, in its open bucket
|
|
// which will be used for the lifetime of this channel.
|
|
nodeAddr := res.nodeAddr
|
|
err = res.partialState.SyncPending(nodeAddr, uint32(bestHeight))
|
|
if err != nil {
|
|
msg.err <- err
|
|
msg.completeChan <- nil
|
|
return
|
|
}
|
|
|
|
walletLog.Infof("Broadcasting funding tx for ChannelPoint(%v): %v",
|
|
res.partialState.FundingOutpoint, spew.Sdump(fundingTx))
|
|
|
|
// Broadcast the finalized funding transaction to the network.
|
|
if err := l.PublishTransaction(fundingTx); err != nil {
|
|
msg.err <- err
|
|
msg.completeChan <- nil
|
|
return
|
|
}
|
|
|
|
msg.completeChan <- res.partialState
|
|
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-existent funding state")
|
|
req.completeChan <- nil
|
|
return
|
|
}
|
|
|
|
// Grab the mutex on the ChannelReservation to ensure thread-safety
|
|
pendingReservation.Lock()
|
|
defer pendingReservation.Unlock()
|
|
|
|
chanState := pendingReservation.partialState
|
|
chanState.FundingOutpoint = *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.
|
|
localBalance := pendingReservation.partialState.LocalCommitment.LocalBalance.ToSatoshis()
|
|
remoteBalance := pendingReservation.partialState.LocalCommitment.RemoteBalance.ToSatoshis()
|
|
ourCommitTx, theirCommitTx, err := CreateCommitmentTxns(
|
|
localBalance, remoteBalance,
|
|
pendingReservation.ourContribution.ChannelConfig,
|
|
pendingReservation.theirContribution.ChannelConfig,
|
|
pendingReservation.ourContribution.FirstCommitmentPoint,
|
|
pendingReservation.theirContribution.FirstCommitmentPoint,
|
|
*fundingTxIn,
|
|
)
|
|
if err != nil {
|
|
req.err <- err
|
|
req.completeChan <- nil
|
|
return
|
|
}
|
|
|
|
// With both commitment transactions constructed, we can now use the
|
|
// generator state obfuscator to encode the current state number within
|
|
// both commitment transactions.
|
|
stateObfuscator := DeriveStateHintObfuscator(
|
|
pendingReservation.theirContribution.PaymentBasePoint.PubKey,
|
|
pendingReservation.ourContribution.PaymentBasePoint.PubKey,
|
|
)
|
|
err = initStateHints(ourCommitTx, theirCommitTx, stateObfuscator)
|
|
if err != nil {
|
|
req.err <- err
|
|
req.completeChan <- nil
|
|
return
|
|
}
|
|
|
|
// Sort both transactions according to the agreed upon canonical
|
|
// ordering. This ensures that both parties sign the same sighash
|
|
// without further synchronization.
|
|
txsort.InPlaceSort(ourCommitTx)
|
|
txsort.InPlaceSort(theirCommitTx)
|
|
chanState.LocalCommitment.CommitTx = ourCommitTx
|
|
chanState.RemoteCommitment.CommitTx = theirCommitTx
|
|
|
|
walletLog.Debugf("Local commit tx for ChannelPoint(%v): %v",
|
|
req.fundingOutpoint, spew.Sdump(ourCommitTx))
|
|
walletLog.Debugf("Remote commit tx for ChannelPoint(%v): %v",
|
|
req.fundingOutpoint, spew.Sdump(theirCommitTx))
|
|
|
|
channelValue := int64(pendingReservation.partialState.Capacity)
|
|
hashCache := txscript.NewTxSigHashes(ourCommitTx)
|
|
theirKey := pendingReservation.theirContribution.MultiSigKey
|
|
ourKey := pendingReservation.ourContribution.MultiSigKey
|
|
witnessScript, _, err := GenFundingPkScript(
|
|
ourKey.PubKey.SerializeCompressed(),
|
|
theirKey.PubKey.SerializeCompressed(), channelValue,
|
|
)
|
|
if err != nil {
|
|
req.err <- err
|
|
req.completeChan <- nil
|
|
return
|
|
}
|
|
|
|
sigHash, err := txscript.CalcWitnessSigHash(witnessScript, hashCache,
|
|
txscript.SigHashAll, ourCommitTx, 0, channelValue)
|
|
if err != nil {
|
|
req.err <- err
|
|
req.completeChan <- nil
|
|
return
|
|
}
|
|
|
|
// Verify that we've received a valid signature from the remote party
|
|
// for our version of the commitment transaction.
|
|
sig, err := btcec.ParseSignature(req.theirCommitmentSig, btcec.S256())
|
|
if err != nil {
|
|
req.err <- err
|
|
req.completeChan <- nil
|
|
return
|
|
} else if !sig.Verify(sigHash, theirKey.PubKey) {
|
|
req.err <- fmt.Errorf("counterparty's commitment signature " +
|
|
"is invalid")
|
|
req.completeChan <- nil
|
|
return
|
|
}
|
|
chanState.LocalCommitment.CommitSig = 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.
|
|
p2wsh, err := witnessScriptHash(witnessScript)
|
|
if err != nil {
|
|
req.err <- err
|
|
req.completeChan <- nil
|
|
return
|
|
}
|
|
signDesc := SignDescriptor{
|
|
WitnessScript: witnessScript,
|
|
KeyDesc: ourKey,
|
|
Output: &wire.TxOut{
|
|
PkScript: p2wsh,
|
|
Value: channelValue,
|
|
},
|
|
HashType: txscript.SigHashAll,
|
|
SigHashes: txscript.NewTxSigHashes(theirCommitTx),
|
|
InputIndex: 0,
|
|
}
|
|
sigTheirCommit, err := l.Cfg.Signer.SignOutputRaw(theirCommitTx, &signDesc)
|
|
if err != nil {
|
|
req.err <- err
|
|
req.completeChan <- nil
|
|
return
|
|
}
|
|
pendingReservation.ourCommitmentSig = sigTheirCommit
|
|
|
|
_, bestHeight, err := l.Cfg.ChainIO.GetBestBlock()
|
|
if err != nil {
|
|
req.err <- err
|
|
req.completeChan <- nil
|
|
return
|
|
}
|
|
|
|
// Add the complete funding transaction to the DB, in it's open bucket
|
|
// which will be used for the lifetime of this channel.
|
|
chanState.LocalChanCfg = pendingReservation.ourContribution.toChanConfig()
|
|
chanState.RemoteChanCfg = pendingReservation.theirContribution.toChanConfig()
|
|
err = chanState.SyncPending(pendingReservation.nodeAddr, uint32(bestHeight))
|
|
if err != nil {
|
|
req.err <- err
|
|
req.completeChan <- nil
|
|
return
|
|
}
|
|
|
|
req.completeChan <- chanState
|
|
req.err <- nil
|
|
|
|
l.limboMtx.Lock()
|
|
delete(l.fundingLimbo, req.pendingFundingID)
|
|
l.limboMtx.Unlock()
|
|
}
|
|
|
|
// selectCoinsAndChange performs coin selection in order to obtain witness
|
|
// outputs which sum to at least 'numCoins' amount of satoshis. If coin
|
|
// selection is successful/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(feeRate SatPerVByte,
|
|
amt 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 across funding transactions.
|
|
l.coinSelectMtx.Lock()
|
|
defer l.coinSelectMtx.Unlock()
|
|
|
|
walletLog.Infof("Performing funding tx coin selection using %v "+
|
|
"sat/vbyte as fee rate", int64(feeRate))
|
|
|
|
// Find all unlocked unspent witness outputs with greater than 1
|
|
// confirmation.
|
|
// TODO(roasbeef): make num confs a configuration parameter
|
|
coins, err := l.ListUnspentWitness(1)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
|
|
// Perform coin selection over our available, unlocked unspent outputs
|
|
// in order to find enough coins to meet the funding amount
|
|
// requirements.
|
|
selectedCoins, changeAmt, err := coinSelect(feeRate, amt, coins)
|
|
if err != nil {
|
|
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))
|
|
for i, coin := range selectedCoins {
|
|
outpoint := &coin.OutPoint
|
|
l.lockedOutPoints[*outpoint] = struct{}{}
|
|
l.LockOutpoint(*outpoint)
|
|
|
|
// Empty sig script, we'll actually sign if this reservation is
|
|
// queued up to be completed (the other side accepts).
|
|
contribution.Inputs[i] = wire.NewTxIn(outpoint, nil, nil)
|
|
}
|
|
|
|
// Record any change output(s) generated as a result of the coin
|
|
// selection, but only if the addition of the output won't lead to the
|
|
// creation of dust.
|
|
if changeAmt != 0 && changeAmt > DefaultDustLimit() {
|
|
changeAddr, err := l.NewAddress(WitnessPubKey, true)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
changeScript, err := txscript.PayToAddrScript(changeAddr)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
|
|
contribution.ChangeOutputs = make([]*wire.TxOut, 1)
|
|
contribution.ChangeOutputs[0] = &wire.TxOut{
|
|
Value: int64(changeAmt),
|
|
PkScript: changeScript,
|
|
}
|
|
}
|
|
|
|
return nil
|
|
}
|
|
|
|
// DeriveStateHintObfuscator derives the bytes to be used for obfuscating the
|
|
// state hints from the root to be used for a new channel. The obfuscator is
|
|
// generated via the following computation:
|
|
//
|
|
// * sha256(initiatorKey || responderKey)[26:]
|
|
// * where both keys are the multi-sig keys of the respective parties
|
|
//
|
|
// The first 6 bytes of the resulting hash are used as the state hint.
|
|
func DeriveStateHintObfuscator(key1, key2 *btcec.PublicKey) [StateHintSize]byte {
|
|
h := sha256.New()
|
|
h.Write(key1.SerializeCompressed())
|
|
h.Write(key2.SerializeCompressed())
|
|
|
|
sha := h.Sum(nil)
|
|
|
|
var obfuscator [StateHintSize]byte
|
|
copy(obfuscator[:], sha[26:])
|
|
|
|
return obfuscator
|
|
}
|
|
|
|
// initStateHints properly sets the obfuscated state hints on both commitment
|
|
// transactions using the passed obfuscator.
|
|
func initStateHints(commit1, commit2 *wire.MsgTx,
|
|
obfuscator [StateHintSize]byte) error {
|
|
|
|
if err := SetStateNumHint(commit1, 0, obfuscator); err != nil {
|
|
return err
|
|
}
|
|
if err := SetStateNumHint(commit2, 0, obfuscator); err != nil {
|
|
return err
|
|
}
|
|
|
|
return nil
|
|
}
|
|
|
|
// selectInputs selects a slice of inputs necessary to meet the specified
|
|
// selection amount. If input selection is unable to succeed due to insufficient
|
|
// funds, a non-nil error is returned. Additionally, the total amount of the
|
|
// selected coins are returned in order for the caller to properly handle
|
|
// change+fees.
|
|
func selectInputs(amt btcutil.Amount, coins []*Utxo) (btcutil.Amount, []*Utxo, error) {
|
|
satSelected := btcutil.Amount(0)
|
|
for i, coin := range coins {
|
|
satSelected += coin.Value
|
|
if satSelected >= amt {
|
|
return satSelected, coins[:i+1], nil
|
|
}
|
|
}
|
|
return 0, nil, &ErrInsufficientFunds{amt, satSelected}
|
|
}
|
|
|
|
// coinSelect attempts to select a sufficient amount of coins, including a
|
|
// change output to fund amt satoshis, adhering to the specified fee rate. The
|
|
// specified fee rate should be expressed in sat/vbyte for coin selection to
|
|
// function properly.
|
|
func coinSelect(feeRate SatPerVByte, amt btcutil.Amount,
|
|
coins []*Utxo) ([]*Utxo, btcutil.Amount, error) {
|
|
|
|
amtNeeded := amt
|
|
for {
|
|
// First perform an initial round of coin selection to estimate
|
|
// the required fee.
|
|
totalSat, selectedUtxos, err := selectInputs(amtNeeded, coins)
|
|
if err != nil {
|
|
return nil, 0, err
|
|
}
|
|
|
|
var weightEstimate TxWeightEstimator
|
|
|
|
for _, utxo := range selectedUtxos {
|
|
switch utxo.AddressType {
|
|
case WitnessPubKey:
|
|
weightEstimate.AddP2WKHInput()
|
|
case NestedWitnessPubKey:
|
|
weightEstimate.AddNestedP2WKHInput()
|
|
default:
|
|
return nil, 0, fmt.Errorf("Unsupported address type: %v",
|
|
utxo.AddressType)
|
|
}
|
|
}
|
|
|
|
// Channel funding multisig output is P2WSH.
|
|
weightEstimate.AddP2WSHOutput()
|
|
|
|
// Assume that change output is a P2WKH output.
|
|
//
|
|
// TODO: Handle wallets that generate non-witness change
|
|
// addresses.
|
|
weightEstimate.AddP2WKHOutput()
|
|
|
|
// The difference between the selected amount and the amount
|
|
// requested will be used to pay fees, and generate a change
|
|
// output with the remaining.
|
|
overShootAmt := totalSat - amt
|
|
|
|
// Based on the estimated size and fee rate, if the excess
|
|
// amount isn't enough to pay fees, then increase the requested
|
|
// coin amount by the estimate required fee, performing another
|
|
// round of coin selection.
|
|
requiredFee := feeRate.FeeForVSize(int64(weightEstimate.VSize()))
|
|
if overShootAmt < requiredFee {
|
|
amtNeeded = amt + requiredFee
|
|
continue
|
|
}
|
|
|
|
// If the fee is sufficient, then calculate the size of the
|
|
// change output.
|
|
changeAmt := overShootAmt - requiredFee
|
|
|
|
return selectedUtxos, changeAmt, nil
|
|
}
|
|
}
|