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lnwallet: properly handle HTLC settles in channel state-machine

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We no longer track HTLC’s by their r-hash within the log into the
index, as we may have multiple HTLC’s that can be redeemed by the same
pre-image. Instead we now use a separate index which is keyed by a
log-index.

Additionally, the SettleHTLC method now also returns the index of the
HTLC being settled which allows the remote party to quickly locate the
HTLC within their log.

This commit also introduces a few trace/debug log messages which will
likely be pruned in the near future
This commit is contained in:
Olaoluwa Osuntokun 2016-07-12 17:35:51 -07:00
parent 06f062e678
commit 7dea354711
No known key found for this signature in database
GPG Key ID: 9CC5B105D03521A2
3 changed files with 56 additions and 33 deletions
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79
lnwallet/channel.go
View File

@ -7,6 +7,7 @@ import (
"sync"
"github.com/btcsuite/fastsha256"
"github.com/davecgh/go-spew/spew"
"github.com/lightningnetwork/lnd/chainntfs"
"github.com/lightningnetwork/lnd/channeldb"
"github.com/lightningnetwork/lnd/lnwire"
@ -144,6 +145,7 @@ type PaymentDescriptor struct {
// isForwarded denotes if an incoming HTLC has been forwarded to any
// possible upstream peers in the route.
isForwarded bool
settled bool
}
// commitment represents a commitment to a new state within an active channel.
@ -331,24 +333,15 @@ type LightningChannel struct {
// commitment. The log is compacted once a revocation is received.
stateUpdateLog *list.List
// entriesByHash is an index into the above log. This index is used to
// logIndex is an index into the above log. This index is used to
// remove Add state updates, once a timeout/settle is received.
entriesByHash map[PaymentHash]*list.Element
// Payment's which we've requested.
// TODO(roasbeef): move into InvoiceRegistry
unfufilledPayments map[PaymentHash]*PaymentRequest
logIndex map[uint32]*list.Element
fundingTxIn *wire.TxIn
fundingP2WSH []byte
// TODO(roasbeef): Stores all previous R values + timeouts for each
// commitment update, plus some other meta-data...Or just use OP_RETURN
// to help out?
// currently going for: nSequence/nLockTime overloading
channelDB *channeldb.DB
// TODO(roasbeef): create and embed 'Service' interface w/ below?
started int32
shutdown int32
@ -374,8 +367,7 @@ func NewLightningChannel(wallet *LightningWallet, events chainntnfs.ChainNotifie
channelState: state,
revocationWindowEdge: state.NumUpdates,
stateUpdateLog: list.New(),
entriesByHash: make(map[PaymentHash]*list.Element),
unfufilledPayments: make(map[PaymentHash]*PaymentRequest),
logIndex: make(map[uint32]*list.Element),
channelDB: chanDB,
}
@ -701,6 +693,13 @@ func (lc *LightningChannel) SignNextCommitment() ([]byte, uint32, error) {
return nil, 0, err
}
log.Tracef("ChannelPoint(%v): extending remote chain to height %v",
lc.channelState.ChanID, newCommitView.height)
log.Tracef("ChannelPoint(%v): remote chain: our_balance=%v, "+
"their_balance=%v, commit_tx: %v", lc.channelState.ChanID,
newCommitView.ourBalance, newCommitView.theirBalance,
spew.Sdump(newCommitView.txn))
// Sign their version of the new commitment transaction.
hashCache := txscript.NewTxSigHashes(newCommitView.txn)
sig, err := txscript.RawTxInWitnessSignature(newCommitView.txn,
@ -762,6 +761,13 @@ func (lc *LightningChannel) ReceiveNewCommitment(rawSig []byte,
return err
}
log.Tracef("ChannelPoint(%v): extending local chain to height %v",
lc.channelState.ChanID, localCommitmentView.height)
log.Tracef("ChannelPoint(%v): local chain: our_balance=%v, "+
"their_balance=%v, commit_tx: %v", lc.channelState.ChanID,
localCommitmentView.ourBalance, localCommitmentView.theirBalance,
spew.Sdump(localCommitmentView.txn))
// Construct the sighash of the commitment transaction corresponding to
// this newly proposed state update.
localCommitTx := localCommitmentView.txn
@ -820,6 +826,10 @@ func (lc *LightningChannel) RevokeCurrentCommitment() (*lnwire.CommitRevocation,
revocationEdge[:])
revocationMsg.NextRevocationHash = fastsha256.Sum256(revocationEdge[:])
log.Tracef("ChannelPoint(%v): revoking height=%v, now at height=%v, window_edge=%v",
lc.channelState.ChanID, lc.localCommitChain.tail().height,
lc.currentHeight+1, lc.revocationWindowEdge)
// Advance our tail, as we've revoked our previous state.
lc.localCommitChain.advanceTail()
@ -833,6 +843,10 @@ func (lc *LightningChannel) RevokeCurrentCommitment() (*lnwire.CommitRevocation,
lc.channelState.OurCommitSig = tail.sig
lc.channelState.NumUpdates++
log.Tracef("ChannelPoint(%v): state transition accepted: "+
"our_balance=%v, their_balance=%v", lc.channelState.ChanID,
tail.ourBalance, tail.theirBalance)
// TODO(roasbeef): use RecordChannelDelta once fin
if err := lc.channelState.FullSync(); err != nil {
return nil, err
@ -920,6 +934,8 @@ func (lc *LightningChannel) ReceiveRevocation(revMsg *lnwire.CommitRevocation) (
// Now that we've verified the revocation update the state of the HTLC
// log as we may be able to prune portions of it now, and update their
// balance.
// TODO(roasbeef): move this out to another func?
// * .CompactLog()
var next *list.Element
var htlcsToForward []*PaymentDescriptor
for e := lc.stateUpdateLog.Front(); e != nil; e = next {
@ -933,8 +949,6 @@ func (lc *LightningChannel) ReceiveRevocation(revMsg *lnwire.CommitRevocation) (
if remoteChainTail >= htlc.removeCommitHeightRemote &&
localChainTail >= htlc.removeCommitHeightLocal {
parentLink := htlc.parent
addHTLC := parentLink.Value.(*PaymentDescriptor)
delete(lc.entriesByHash, addHTLC.RHash)
lc.stateUpdateLog.Remove(e)
lc.stateUpdateLog.Remove(parentLink)
}
@ -1003,9 +1017,7 @@ func (lc *LightningChannel) AddHTLC(htlc *lnwire.HTLCAddRequest, incoming bool)
}
pd.Index = index
pdLink := lc.stateUpdateLog.PushBack(pd)
// TODO(roabeef): this should be by HTLC key instead
lc.entriesByHash[pd.RHash] = pdLink
lc.stateUpdateLog.PushBack(pd)
return nil
}
@ -1015,22 +1027,34 @@ func (lc *LightningChannel) AddHTLC(htlc *lnwire.HTLCAddRequest, incoming bool)
// be false, when receiving a settlement to a previously outgoing HTLC, then
// the value of incoming should be true. If the settlement fails due to an
// invalid preimage, then an error is returned.
func (lc *LightningChannel) SettleHTLC(msg *lnwire.HTLCSettleRequest, incoming bool) error {
preImage := msg.RedemptionProofs[0]
func (lc *LightningChannel) SettleHTLC(preimage [32]byte, incoming bool) (uint32, error) {
var targetHTLC *list.Element
paymentHash := PaymentHash(fastsha256.Sum256(preImage[:]))
htlc, ok := lc.entriesByHash[paymentHash]
if !ok {
return fmt.Errorf("unknown payment hash")
// TODO(roasbeef): optimize
paymentHash := fastsha256.Sum256(preimage[:])
for e := lc.stateUpdateLog.Back(); e != nil; e = e.Next() {
htlc := e.Value.(*PaymentDescriptor)
if htlc.entryType != Add {
continue
}
if bytes.Equal(htlc.RHash[:], paymentHash[:]) && !htlc.settled {
htlc.settled = true
targetHTLC = e
break
}
}
if targetHTLC == nil {
return 0, fmt.Errorf("invalid payment hash")
}
parentPd := htlc.Value.(*PaymentDescriptor)
parentPd := targetHTLC.Value.(*PaymentDescriptor)
// TODO(roasbeef): maybe make the log entries an interface?
pd := &PaymentDescriptor{}
pd.IsIncoming = parentPd.IsIncoming
pd.Amount = parentPd.Amount
pd.parent = htlc
pd.parent = targetHTLC
pd.entryType = Settle
var index uint32
@ -1045,7 +1069,7 @@ func (lc *LightningChannel) SettleHTLC(msg *lnwire.HTLCSettleRequest, incoming b
pd.Index = index
lc.stateUpdateLog.PushBack(pd)
return nil
return targetHTLC.Value.(*PaymentDescriptor).Index, nil
}
// TimeoutHTLC...
@ -1278,6 +1302,7 @@ func createCommitTx(fundingOutput *wire.TxIn, selfKey, theirKey *btcec.PublicKey
commitTx := wire.NewMsgTx()
commitTx.Version = 2
commitTx.AddTxIn(fundingOutput)
// TODO(roasbeef): don't make 0 BTC output...
commitTx.AddTxOut(wire.NewTxOut(int64(amountToSelf), payToUsScriptHash))
commitTx.AddTxOut(wire.NewTxOut(int64(amountToThem), theirWitnessKeyHash))

7
lnwallet/channel_test.go
View File

@ -329,13 +329,10 @@ func TestSimpleAddSettleWorkflow(t *testing.T) {
// HTLC once he learns of the preimage.
var preimage [32]byte
copy(preimage[:], paymentPreimage)
wireSettleMsg := &lnwire.HTLCSettleRequest{
RedemptionProofs: [][32]byte{preimage},
}
if err := bobChannel.SettleHTLC(wireSettleMsg, false); err != nil {
if _, err := bobChannel.SettleHTLC(preimage, false); err != nil {
t.Fatalf("bob unable to settle inbound htlc: %v", err)
}
if err := aliceChannel.SettleHTLC(wireSettleMsg, true); err != nil {
if _, err := aliceChannel.SettleHTLC(preimage, true); err != nil {
t.Fatalf("alice unable to accept settle of outbound htlc: %v", err)
}
bobSig2, aliceIndex2, err := bobChannel.SignNextCommitment()

3
lnwallet/script_utils.go
View File

@ -348,7 +348,8 @@ func senderHtlcSpendTimeout(commitScript []byte, outputAmt btcutil.Amount,
// OP_ENDIF
// <sender key> OP_CHECKSIG
// OP_ENDIF
// TODO(roasbeef): rename these to sender vs receiver?
// TODO(roasbeef): go back to revocation keys in the HTLC outputs?
// * also could combine pre-image with their key?
func receiverHTLCScript(absoluteTimeout, relativeTimeout uint32, senderKey,
receiverKey *btcec.PublicKey, revokeHash, paymentHash []byte) ([]byte, error) {