597 lines
18 KiB
Go
597 lines
18 KiB
Go
package lnwallet
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import (
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"bytes"
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"fmt"
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"sync"
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"github.com/lightningnetwork/lnd/chainntfs"
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"github.com/lightningnetwork/lnd/channeldb"
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"github.com/btcsuite/btcd/btcec"
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"github.com/btcsuite/btcd/txscript"
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"github.com/btcsuite/btcd/wire"
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"github.com/btcsuite/btcutil"
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"github.com/btcsuite/btcutil/txsort"
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)
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const (
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// TODO(roasbeef): make not random value
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MaxPendingPayments = 10
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)
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// PaymentHash presents the hash160 of a random value. This hash is used to
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// uniquely track incoming/outgoing payments within this channel, as well as
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// payments requested by the wallet/daemon.
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type PaymentHash [20]byte
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// LightningChannel...
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// TODO(roasbeef): future peer struct should embed this struct
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type LightningChannel struct {
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lnwallet *LightningWallet
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channelEvents chainntnfs.ChainNotifier
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// TODO(roasbeef): Stores all previous R values + timeouts for each
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// commitment update, plus some other meta-data...Or just use OP_RETURN
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// to help out?
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// currently going for: nSequence/nLockTime overloading
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channelDB *channeldb.DB
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// stateMtx protects concurrent access to the state struct.
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stateMtx sync.RWMutex
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channelState *channeldb.OpenChannel
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updateTotem chan struct{}
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// Uncleared HTLC's.
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pendingPayments map[PaymentHash]*PaymentDescriptor
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// Payment's which we've requested.
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unfufilledPayments map[PaymentHash]*PaymentRequest
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fundingTxIn *wire.TxIn
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fundingP2SH []byte
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// TODO(roasbeef): create and embed 'Service' interface w/ below?
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started int32
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shutdown int32
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quit chan struct{}
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wg sync.WaitGroup
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}
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// newLightningChannel...
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func newLightningChannel(wallet *LightningWallet, events chainntnfs.ChainNotifier,
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chanDB *channeldb.DB, state *channeldb.OpenChannel) (*LightningChannel, error) {
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lc := &LightningChannel{
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lnwallet: wallet,
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channelEvents: events,
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channelState: state,
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channelDB: chanDB,
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updateTotem: make(chan struct{}, 1),
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pendingPayments: make(map[PaymentHash]*PaymentDescriptor),
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unfufilledPayments: make(map[PaymentHash]*PaymentRequest),
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}
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// TODO(roasbeef): do a NotifySpent for the funding input, and
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// NotifyReceived for all commitment outputs.
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// Populate the totem.
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lc.updateTotem <- struct{}{}
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fundingTxId := state.FundingTx.TxSha()
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fundingPkScript, err := scriptHashPkScript(state.FundingRedeemScript)
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if err != nil {
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return nil, err
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}
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_, multiSigIndex := findScriptOutputIndex(state.FundingTx, fundingPkScript)
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lc.fundingTxIn = wire.NewTxIn(wire.NewOutPoint(&fundingTxId, multiSigIndex), nil)
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lc.fundingP2SH = fundingPkScript
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return lc, nil
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}
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// PaymentDescriptor...
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type PaymentDescriptor struct {
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RHash [20]byte
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Timeout uint32
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Value btcutil.Amount
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OurRevocation [20]byte // TODO(roasbeef): don't need these?
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TheirRevocation [20]byte
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PayToUs bool
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}
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// ChannelUpdate...
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type ChannelUpdate struct {
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pendingDesc *PaymentDescriptor
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deletion bool
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currentUpdateNum uint64
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pendingUpdateNum uint64
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ourPendingCommitTx *wire.MsgTx
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theirPendingCommitTx *wire.MsgTx
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pendingRevocation [20]byte
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sigTheirNewCommit []byte
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// TODO(roasbeef): some enum to track current state in lifetime?
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// state UpdateStag
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lnChannel *LightningChannel
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}
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// RevocationHash...
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func (c *ChannelUpdate) RevocationHash() ([]byte, error) {
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c.lnChannel.stateMtx.RLock()
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defer c.lnChannel.stateMtx.RUnlock()
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shachain := c.lnChannel.channelState.OurShaChain
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nextPreimage, err := shachain.GetHash(c.pendingUpdateNum)
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if err != nil {
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return nil, err
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}
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return btcutil.Hash160(nextPreimage[:]), nil
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}
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// SignCounterPartyCommitment...
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func (c *ChannelUpdate) SignCounterPartyCommitment() ([]byte, error) {
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c.lnChannel.stateMtx.RLock()
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defer c.lnChannel.stateMtx.RUnlock()
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if c.sigTheirNewCommit != nil {
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return c.sigTheirNewCommit, nil
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}
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// Sign their version of the commitment transaction.
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sig, err := txscript.RawTxInSignature(c.theirPendingCommitTx, 0,
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c.lnChannel.channelState.FundingRedeemScript, txscript.SigHashAll,
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c.lnChannel.channelState.MultiSigKey)
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if err != nil {
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return nil, err
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}
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c.sigTheirNewCommit = sig
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return sig, nil
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}
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// PreviousRevocationPreImage...
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func (c *ChannelUpdate) PreviousRevocationPreImage() ([]byte, error) {
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c.lnChannel.stateMtx.RLock()
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defer c.lnChannel.stateMtx.RUnlock()
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// Retrieve the pre-image to the revocation hash our current commitment
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// transaction.
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shachain := c.lnChannel.channelState.OurShaChain
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revokePreImage, err := shachain.GetHash(c.currentUpdateNum)
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if err != nil {
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return nil, err
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}
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return revokePreImage[:], nil
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}
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// VerifyNewCommitmentSigs...
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func (c *ChannelUpdate) VerifyNewCommitmentSigs(ourSig, theirSig []byte) error {
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c.lnChannel.stateMtx.RLock()
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defer c.lnChannel.stateMtx.RUnlock()
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var err error
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var scriptSig []byte
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channelState := c.lnChannel.channelState
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// When initially generating the redeemScript, we sorted the serialized
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// public keys in descending order. So we do a quick comparison in order
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// ensure the signatures appear on the Script Virual Machine stack in
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// the correct order.
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redeemScript := channelState.FundingRedeemScript
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ourKey := channelState.OurCommitKey.PubKey().SerializeCompressed()
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theirKey := channelState.TheirCommitKey.SerializeCompressed()
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scriptSig, err = spendMultiSig(redeemScript, ourKey, ourSig, theirKey, theirSig)
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if err != nil {
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return err
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}
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// Attach the scriptSig to our commitment transaction's only input,
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// then validate that the scriptSig executes correctly.
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commitTx := c.ourPendingCommitTx
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commitTx.TxIn[0].SignatureScript = scriptSig
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vm, err := txscript.NewEngine(c.lnChannel.fundingP2SH, commitTx, 0,
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txscript.StandardVerifyFlags, nil)
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if err != nil {
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return err
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}
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return vm.Execute()
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}
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// Commit...
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func (c *ChannelUpdate) Commit(pastRevokePreimage []byte) error {
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c.lnChannel.stateMtx.Lock()
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defer c.lnChannel.stateMtx.Unlock()
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// First, ensure that the pre-image properly links into the shachain.
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theirShaChain := c.lnChannel.channelState.TheirShaChain
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var preImage [32]byte
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copy(preImage[:], pastRevokePreimage)
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if err := theirShaChain.AddNextHash(preImage); err != nil {
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return err
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}
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channelState := c.lnChannel.channelState
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// Finally, verify that that this is indeed the pre-image to the
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// revocation hash we were given earlier.
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if !bytes.Equal(btcutil.Hash160(pastRevokePreimage),
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channelState.TheirCurrentRevocation[:]) {
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return fmt.Errorf("pre-image hash does not match revocation")
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}
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// Store this current revocation in the channel state so we can
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// verify future channel updates.
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channelState.TheirCurrentRevocation = c.pendingRevocation
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// The channel update is now complete, roll over to the newest commitment
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// transaction.
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channelState.OurCommitTx = c.ourPendingCommitTx
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channelState.TheirCommitTx = c.theirPendingCommitTx
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channelState.NumUpdates = c.pendingUpdateNum
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// If this channel update involved deleting an HTLC, remove it from the
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// set of pending payments.
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if c.deletion {
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delete(c.lnChannel.pendingPayments, c.pendingDesc.RHash)
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}
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// TODO(roasbeef): db writes, checkpoints, and such
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// Return the updateTotem, allowing another update to be created now
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// that this pending update has been commited, and finalized.
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c.lnChannel.updateTotem <- struct{}{}
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return nil
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}
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// AddHTLC...
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// 1. request R_Hash from receiver (only if single hop, would be out of band)
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// 2. propose HTLC
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// * timeout
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// * value
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// * r_hash
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// * next revocation hash
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// 3. they accept
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// * their next revocation hash
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// * their sig for our new commitment tx (verify correctness)
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// Can buld both new commitment txns at this point
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// 4. we give sigs
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// * our sigs for their new commitment tx
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// * the pre-image to our old commitment tx
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// 5. they complete
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// * the pre-image to their old commitment tx (verify is part of their chain, is pre-image)
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func (lc *LightningChannel) AddHTLC(timeout uint32, value btcutil.Amount,
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rHash, revocation PaymentHash, payToUs bool) (*ChannelUpdate, error) {
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// Grab the updateTotem, this acts as a barrier upholding the invariant
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// that only one channel update transaction should exist at any moment.
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// This aides in ensuring the channel updates are atomic, and consistent.
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<-lc.updateTotem
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chanUpdate := &ChannelUpdate{
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pendingDesc: &PaymentDescriptor{
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RHash: rHash,
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TheirRevocation: revocation,
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Timeout: timeout,
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Value: value,
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PayToUs: payToUs,
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},
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pendingRevocation: revocation,
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lnChannel: lc,
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}
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// Get next revocation hash, updating the number of updates in the
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// channel as a result.
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chanUpdate.currentUpdateNum = lc.channelState.NumUpdates
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chanUpdate.pendingUpdateNum = lc.channelState.NumUpdates + 1
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nextPreimage, err := lc.channelState.OurShaChain.GetHash(chanUpdate.pendingUpdateNum)
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if err != nil {
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return nil, err
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}
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copy(chanUpdate.pendingDesc.OurRevocation[:], btcutil.Hash160(nextPreimage[:]))
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// Re-calculate the amount of cleared funds for each side.
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var amountToUs, amountToThem btcutil.Amount
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if payToUs {
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amountToUs = lc.channelState.OurBalance
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amountToThem = lc.channelState.TheirBalance - value
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} else {
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amountToUs = lc.channelState.OurBalance - value
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amountToThem = lc.channelState.TheirBalance
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}
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// Re-create copies of the current commitment transactions to be updated.
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ourNewCommitTx, theirNewCommitTx, err := createNewCommitmentTxns(
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lc.fundingTxIn, lc.channelState, chanUpdate, amountToUs, amountToThem,
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)
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if err != nil {
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return nil, err
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}
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// First, re-add all the old HTLCs.
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for _, paymentDesc := range lc.pendingPayments {
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if err := lc.addHTLC(ourNewCommitTx, theirNewCommitTx, paymentDesc); err != nil {
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return nil, err
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}
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}
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// Then add this new HTLC.
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if err := lc.addHTLC(ourNewCommitTx, theirNewCommitTx, chanUpdate.pendingDesc); err != nil {
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return nil, err
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}
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lc.pendingPayments[rHash] = chanUpdate.pendingDesc // TODO(roasbeef): check for dups?
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// Sort both transactions according to the agreed upon cannonical
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// ordering. This lets us skip sending the entire transaction over,
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// instead we'll just send signatures.
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txsort.InPlaceSort(ourNewCommitTx)
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txsort.InPlaceSort(theirNewCommitTx)
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// TODO(roasbeef): locktimes/sequence set
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// TODO(roasbeef): write checkpoint here...
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chanUpdate.ourPendingCommitTx = ourNewCommitTx
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chanUpdate.theirPendingCommitTx = theirNewCommitTx
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return chanUpdate, nil
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}
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// addHTLC...
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// NOTE: This MUST be called with stateMtx held.
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func (lc *LightningChannel) addHTLC(ourCommitTx, theirCommitTx *wire.MsgTx,
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paymentDesc *PaymentDescriptor) error {
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// If the HTLC is going to us, then we're the sender, otherwise they
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// are.
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var senderKey, receiverKey *btcec.PublicKey
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var senderRevocation, receiverRevocation []byte
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if paymentDesc.PayToUs {
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receiverKey = lc.channelState.OurCommitKey.PubKey()
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receiverRevocation = paymentDesc.OurRevocation[:]
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senderKey = lc.channelState.TheirCommitKey
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senderRevocation = paymentDesc.TheirRevocation[:]
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} else {
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senderKey = lc.channelState.OurCommitKey.PubKey()
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senderRevocation = paymentDesc.OurRevocation[:]
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receiverKey = lc.channelState.TheirCommitKey
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receiverRevocation = paymentDesc.TheirRevocation[:]
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}
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// Generate the proper redeem scripts for the HTLC output for both the
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// sender and the receiver.
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timeout := paymentDesc.Timeout
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rHash := paymentDesc.RHash
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delay := lc.channelState.CsvDelay
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senderPKScript, err := senderHTLCScript(timeout, delay, senderKey,
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receiverKey, senderRevocation[:], rHash[:])
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if err != nil {
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return nil
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}
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receiverPKScript, err := receiverHTLCScript(timeout, delay, senderKey,
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receiverKey, receiverRevocation[:], rHash[:])
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if err != nil {
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return nil
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}
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// Now that we have the redeem scripts, create the P2SH public key
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// script for each.
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senderP2SH, err := scriptHashPkScript(senderPKScript)
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if err != nil {
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return nil
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}
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receiverP2SH, err := scriptHashPkScript(receiverPKScript)
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if err != nil {
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return nil
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}
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// Add the new HTLC outputs to the respective commitment transactions.
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amountPending := int64(paymentDesc.Value)
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if paymentDesc.PayToUs {
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ourCommitTx.AddTxOut(wire.NewTxOut(amountPending, receiverP2SH))
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theirCommitTx.AddTxOut(wire.NewTxOut(amountPending, senderP2SH))
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} else {
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ourCommitTx.AddTxOut(wire.NewTxOut(amountPending, senderP2SH))
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theirCommitTx.AddTxOut(wire.NewTxOut(amountPending, receiverP2SH))
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}
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return nil
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}
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// SettleHTLC...
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// R-VALUE, NEW REVOKE HASH
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// accept, sig
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func (lc *LightningChannel) SettleHTLC(rValue [20]byte, newRevocation [20]byte) (*ChannelUpdate, error) {
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// Grab the updateTotem, this acts as a barrier upholding the invariant
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// that only one channel update transaction should exist at any moment.
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// This aides in ensuring the channel updates are atomic, and consistent.
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<-lc.updateTotem
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// Find the matching payment descriptor, bailing out early if it
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// doesn't exist.
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var rHash PaymentHash
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copy(rHash[:], btcutil.Hash160(rValue[:]))
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payDesc, ok := lc.pendingPayments[rHash]
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if !ok {
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return nil, fmt.Errorf("r-hash for preimage not found")
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}
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chanUpdate := &ChannelUpdate{
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pendingDesc: payDesc,
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deletion: true,
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pendingRevocation: newRevocation,
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lnChannel: lc,
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}
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// TODO(roasbeef): such copy pasta, make into func...
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// Get next revocation hash, updating the number of updates in the
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// channel as a result.
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chanUpdate.currentUpdateNum = lc.channelState.NumUpdates
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chanUpdate.pendingUpdateNum = lc.channelState.NumUpdates + 1
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nextPreimage, err := lc.channelState.OurShaChain.GetHash(chanUpdate.pendingUpdateNum)
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if err != nil {
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return nil, err
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}
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copy(chanUpdate.pendingDesc.OurRevocation[:], btcutil.Hash160(nextPreimage[:]))
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// Re-calculate the amount of cleared funds for each side.
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var amountToUs, amountToThem btcutil.Amount
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if payDesc.PayToUs {
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amountToUs = lc.channelState.OurBalance + payDesc.Value
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amountToThem = lc.channelState.TheirBalance
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} else {
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amountToUs = lc.channelState.OurBalance
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amountToThem = lc.channelState.TheirBalance + payDesc.Value
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}
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// Create new commitment transactions that reflect the settlement of
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// this pending HTLC.
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ourNewCommitTx, theirNewCommitTx, err := createNewCommitmentTxns(
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lc.fundingTxIn, lc.channelState, chanUpdate, amountToUs, amountToThem,
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)
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if err != nil {
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return nil, err
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}
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// Re-add all the HTLC's skipping over this newly settled payment.
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for paymentHash, paymentDesc := range lc.pendingPayments {
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if bytes.Equal(paymentHash[:], rHash[:]) {
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continue
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}
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if err := lc.addHTLC(ourNewCommitTx, theirNewCommitTx, paymentDesc); err != nil {
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return nil, err
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}
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}
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// Sort both transactions according to the agreed upon cannonical
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// ordering. This lets us skip sending the entire transaction over,
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// instead we'll just send signatures.
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txsort.InPlaceSort(ourNewCommitTx)
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txsort.InPlaceSort(theirNewCommitTx)
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// TODO(roasbeef): locktimes/sequence set
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// TODO(roasbeef): write checkpoint here...
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chanUpdate.ourPendingCommitTx = ourNewCommitTx
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chanUpdate.theirPendingCommitTx = theirNewCommitTx
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return chanUpdate, nil
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}
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// createNewCommitmentTxns....
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// NOTE: This MUST be called with stateMtx held.
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func createNewCommitmentTxns(fundingTxIn *wire.TxIn, state *channeldb.OpenChannel,
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chanUpdate *ChannelUpdate, amountToUs, amountToThem btcutil.Amount) (*wire.MsgTx, *wire.MsgTx, error) {
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ourNewCommitTx, err := createCommitTx(fundingTxIn,
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state.OurCommitKey.PubKey(), state.TheirCommitKey,
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chanUpdate.pendingDesc.OurRevocation[:], state.CsvDelay,
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amountToUs, amountToThem)
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if err != nil {
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return nil, nil, err
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}
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theirNewCommitTx, err := createCommitTx(fundingTxIn,
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state.TheirCommitKey, state.OurCommitKey.PubKey(),
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chanUpdate.pendingDesc.TheirRevocation[:], state.CsvDelay,
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|
amountToThem, amountToUs)
|
|
if err != nil {
|
|
return nil, nil, err
|
|
}
|
|
|
|
return ourNewCommitTx, theirNewCommitTx, nil
|
|
}
|
|
|
|
// CancelHTLC...
|
|
func (lc *LightningChannel) CancelHTLC() error {
|
|
return nil
|
|
}
|
|
|
|
// OurBalance...
|
|
func (lc *LightningChannel) OurBalance() btcutil.Amount {
|
|
lc.stateMtx.RLock()
|
|
defer lc.stateMtx.RUnlock()
|
|
return lc.channelState.OurBalance
|
|
}
|
|
|
|
// TheirBalance...
|
|
func (lc *LightningChannel) TheirBalance() btcutil.Amount {
|
|
lc.stateMtx.RLock()
|
|
defer lc.stateMtx.RUnlock()
|
|
return lc.channelState.TheirBalance
|
|
}
|
|
|
|
// ForceClose...
|
|
func (lc *LightningChannel) ForceClose() error {
|
|
return nil
|
|
}
|
|
|
|
// RequestPayment...
|
|
func (lc *LightningChannel) RequestPayment(amount btcutil.Amount) error {
|
|
// Validate amount
|
|
return nil
|
|
}
|
|
|
|
// PaymentRequest...
|
|
// TODO(roasbeef): serialization (bip 70, QR code, etc)
|
|
// * routing handled by upper layer
|
|
type PaymentRequest struct {
|
|
PaymentPreImage [20]byte
|
|
Value btcutil.Amount
|
|
}
|
|
|
|
// createCommitTx...
|
|
// TODO(roasbeef): fix inconsistency of 32 vs 20 byte revocation hashes everywhere...
|
|
func createCommitTx(fundingOutput *wire.TxIn, selfKey, theirKey *btcec.PublicKey,
|
|
revokeHash []byte, csvTimeout uint32, amountToSelf,
|
|
amountToThem btcutil.Amount) (*wire.MsgTx, error) {
|
|
|
|
// First, we create the script for the delayed "pay-to-self" output.
|
|
ourRedeemScript, err := commitScriptToSelf(csvTimeout, selfKey, theirKey,
|
|
revokeHash)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
payToUsScriptHash, err := scriptHashPkScript(ourRedeemScript)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
// Next, we create the script paying to them. This is just a regular
|
|
// P2PKH-like output, without any added CSV delay. However, we instead
|
|
// use P2SH.
|
|
theirRedeemScript, err := commitScriptUnencumbered(theirKey)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
payToThemScriptHash, err := scriptHashPkScript(theirRedeemScript)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
// Now that both output scripts have been created, we can finally create
|
|
// the transaction itself. We use a transaction version of 2 since CSV
|
|
// will fail unless the tx version is >= 2.
|
|
commitTx := wire.NewMsgTx()
|
|
commitTx.Version = 2
|
|
commitTx.AddTxIn(fundingOutput)
|
|
commitTx.AddTxOut(wire.NewTxOut(int64(amountToSelf), payToUsScriptHash))
|
|
commitTx.AddTxOut(wire.NewTxOut(int64(amountToThem), payToThemScriptHash))
|
|
|
|
return commitTx, nil
|
|
}
|