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contractcourt: simplify htlcTimeoutResolver, unify with HTLC contest logic

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In this commit, we simplify the existing `htlcTImeoutResolver` with some
newly refactored out methods from the `htlcTimeoutContestResolver`. The
resulting logic is easier to follow as it's more linear, and only deals
with spend notifications rather than both spend _and_ confirmation
notifications.
This commit is contained in:
Olaoluwa Osuntokun 2019-03-18 17:04:19 -07:00
parent e1a07b68e8
commit 6b24b6dabd
No known key found for this signature in database
GPG Key ID: CE58F7F8E20FD9A2
2 changed files with 113 additions and 61 deletions
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35
contractcourt/channel_arbitrator_test.go
View File

@ -511,8 +511,10 @@ func TestChannelArbitratorLocalForceClosePendingHtlc(t *testing.T) {
// The force close request should trigger broadcast of the commitment
// transaction.
assertStateTransitions(t, arbLog.newStates,
StateBroadcastCommit, StateCommitmentBroadcasted)
assertStateTransitions(
t, arbLog.newStates, StateBroadcastCommit,
StateCommitmentBroadcasted,
)
select {
case <-respChan:
case <-time.After(5 * time.Second):
@ -529,7 +531,17 @@ func TestChannelArbitratorLocalForceClosePendingHtlc(t *testing.T) {
}
// Now notify about the local force close getting confirmed.
closeTx := &wire.MsgTx{}
closeTx := &wire.MsgTx{
TxIn: []*wire.TxIn{
{
PreviousOutPoint: wire.OutPoint{},
Witness: [][]byte{
{0x1},
{0x2},
},
},
},
}
htlcOp := wire.OutPoint{
Hash: closeTx.TxHash(),
@ -569,8 +581,10 @@ func TestChannelArbitratorLocalForceClosePendingHtlc(t *testing.T) {
&channeldb.ChannelCloseSummary{},
}
assertStateTransitions(t, arbLog.newStates, StateContractClosed,
StateWaitingFullResolution)
assertStateTransitions(
t, arbLog.newStates, StateContractClosed,
StateWaitingFullResolution,
)
// htlcOutgoingContestResolver is now active and waiting for the HTLC to
// expire. It should not yet have passed it on for incubation.
@ -592,12 +606,13 @@ func TestChannelArbitratorLocalForceClosePendingHtlc(t *testing.T) {
t.Fatalf("no response received")
}
// Notify resolver that output of the commitment has been spent.
notifier.confChan <- &chainntnfs.TxConfirmation{}
// Notify resolver that the HTLC output of the commitment has been
// spent.
notifier.spendChan <- &chainntnfs.SpendDetail{SpendingTx: closeTx}
// As this is our own commitment transaction, the HTLC will go through
// to the second level. Channel arbitrator should still not be marked as
// resolved.
// to the second level. Channel arbitrator should still not be marked
// as resolved.
select {
case <-resolved:
t.Fatalf("channel resolved prematurely")
@ -605,7 +620,7 @@ func TestChannelArbitratorLocalForceClosePendingHtlc(t *testing.T) {
}
// Notify resolver that the second level transaction is spent.
notifier.spendChan <- &chainntnfs.SpendDetail{}
notifier.spendChan <- &chainntnfs.SpendDetail{SpendingTx: closeTx}
// At this point channel should be marked as resolved.
assertStateTransitions(t, arbLog.newStates, StateFullyResolved)

139
contractcourt/htlc_timeout_resolver.go
View File

@ -91,7 +91,9 @@ const (
// claimCleanUp is a helper method that's called once the HTLC output is spent
// by the remote party. It'll extract the preimage, add it to the global cache,
// and finally send the appropriate clean up message.
func (h *htlcTimeoutResolver) claimCleanUp(commitSpend *chainntnfs.SpendDetail) (ContractResolver, error) {
func (h *htlcTimeoutResolver) claimCleanUp(
commitSpend *chainntnfs.SpendDetail) (ContractResolver, error) {
// Depending on if this is our commitment or not, then we'll be looking
// for a different witness pattern.
spenderIndex := commitSpend.SpenderInputIndex
@ -172,15 +174,51 @@ func (h *htlcTimeoutResolver) chainDetailsToWatch() (*wire.OutPoint, []byte, err
// we need to watch.
outPointToWatch := h.htlcResolution.SignedTimeoutTx.TxIn[0].PreviousOutPoint
witness := h.htlcResolution.SignedTimeoutTx.TxIn[0].Witness
scriptToWatch, err := input.WitnessScriptHash(
witness[len(witness)-1],
)
scriptToWatch, err := input.WitnessScriptHash(witness[len(witness)-1])
if err != nil {
return nil, nil, err
}
return &outPointToWatch, scriptToWatch, nil
}
// isSuccessSpend returns true if the passed spend on the specified commitment
// is a success spend that reveals the pre-image or not.
func isSuccessSpend(spend *chainntnfs.SpendDetail, localCommit bool) bool {
// Based on the spending input index and transaction, obtain the
// witness that tells us what type of spend this is.
spenderIndex := spend.SpenderInputIndex
spendingInput := spend.SpendingTx.TxIn[spenderIndex]
spendingWitness := spendingInput.Witness
// If this is the remote commitment then the only possible spends for
// outgoing HTLCs are:
//
// RECVR: <0> <sender sig> <recvr sig> <preimage> (2nd level success spend)
// REVOK: <sig> <key>
// SENDR: <sig> 0
//
// In this case, if 5 witness elements are present (factoring the
// witness script), and the 3rd element is the size of the pre-image,
// then this is a remote spend. If not, then we swept it ourselves, or
// revoked their output.
if !localCommit {
return len(spendingWitness) == expectedRemoteWitnessSuccessSize &&
len(spendingWitness[remotePreimageIndex]) == lntypes.HashSize
}
// Otherwise, for our commitment, the only possible spends for an
// outgoing HTLC are:
//
// SENDR: <0> <sendr sig> <recvr sig> <0> (2nd level timeout)
// RECVR: <recvr sig> <preimage>
// REVOK: <revoke sig> <revoke key>
//
// So the only success case has the pre-image as the 2nd (index 1)
// element in the witness.
return len(spendingWitness[localPreimageIndex]) == lntypes.HashSize
}
// Resolve kicks off full resolution of an outgoing HTLC output. If it's our
// commitment, it isn't resolved until we see the second level HTLC txn
// confirmed. If it's the remote party's commitment, we don't resolve until we
@ -243,60 +281,59 @@ func (h *htlcTimeoutResolver) Resolve() (ContractResolver, error) {
return nil
}
// With the output sent to the nursery, we'll now wait until the output
// has been fully resolved before sending the clean up message.
//
// TODO(roasbeef): need to be able to cancel nursery?
// * if they pull on-chain while we're waiting
// If we don't have a second layer transaction, then this is a remote
// party's commitment, so we'll watch for a direct spend.
if h.htlcResolution.SignedTimeoutTx == nil {
// We'll block until: the HTLC output has been spent, and the
// transaction spending that output is sufficiently confirmed.
log.Infof("%T(%v): waiting for nursery to spend CLTV-locked "+
"output", h, h.htlcResolution.ClaimOutpoint)
if err := waitForOutputResolution(); err != nil {
return nil, err
}
} else {
// Otherwise, this is our commitment, so we'll watch for the
// second-level transaction to be sufficiently confirmed.
secondLevelTXID := h.htlcResolution.SignedTimeoutTx.TxHash()
sweepScript := h.htlcResolution.SignedTimeoutTx.TxOut[0].PkScript
confNtfn, err := h.Notifier.RegisterConfirmationsNtfn(
&secondLevelTXID, sweepScript, 1, h.broadcastHeight,
)
if err != nil {
return nil, err
}
log.Infof("%T(%v): waiting second-level tx (txid=%v) to be "+
"fully confirmed", h, h.htlcResolution.ClaimOutpoint,
secondLevelTXID)
select {
case _, ok := <-confNtfn.Confirmed:
if !ok {
return nil, fmt.Errorf("quitting")
}
case <-h.Quit:
return nil, fmt.Errorf("quitting")
}
// Now that we've handed off the HTLC to the nursery, we'll watch for a
// spend of the output, and make our next move off of that. Depending
// on if this is our commitment, or the remote party's commitment,
// we'll be watching a different outpoint and script.
outpointToWatch, scriptToWatch, err := h.chainDetailsToWatch()
if err != nil {
return nil, err
}
spendNtfn, err := h.Notifier.RegisterSpendNtfn(
outpointToWatch, scriptToWatch, h.broadcastHeight,
)
if err != nil {
return nil, err
}
// TODO(roasbeef): need to watch for remote party sweeping with pre-image?
// * have another waiting on spend above, will check the type, if it's
// pre-image, then we'll cancel, and send a clean up back with
// pre-image, also add to preimage cache
log.Infof("%T(%v): waiting for HTLC output %v to be spent"+
"fully confirmed", h, h.htlcResolution.ClaimOutpoint,
outpointToWatch)
// We'll block here until either we exit, or the HTLC output on the
// commitment transaction has been spent.
var (
spend *chainntnfs.SpendDetail
ok bool
)
select {
case spend, ok = <-spendNtfn.Spend:
if !ok {
return nil, fmt.Errorf("quitting")
}
case <-h.Quit:
return nil, fmt.Errorf("quitting")
}
// If the spend reveals the pre-image, then we'll enter the clean up
// workflow to pass the pre-image back to the incoming link, add it to
// the witness cache, and exit.
if isSuccessSpend(spend, h.htlcResolution.SignedTimeoutTx != nil) {
log.Infof("%T(%v): HTLC has been swept with pre-image by "+
"remote party during timeout flow! Adding pre-image to "+
"witness cache", h.htlcResolution.ClaimOutpoint)
return h.claimCleanUp(spend)
}
log.Infof("%T(%v): resolving htlc with incoming fail msg, fully "+
"confirmed", h, h.htlcResolution.ClaimOutpoint)
// At this point, the second-level transaction is sufficiently
// confirmed, or a transaction directly spending the output is.
// Therefore, we can now send back our clean up message.
// Therefore, we can now send back our clean up message, failing the
// HTLC on the incoming link.
failureMsg := &lnwire.FailPermanentChannelFailure{}
if err := h.DeliverResolutionMsg(ResolutionMsg{
SourceChan: h.ShortChanID,
@ -307,7 +344,7 @@ func (h *htlcTimeoutResolver) Resolve() (ContractResolver, error) {
}
// Finally, if this was an output on our commitment transaction, we'll
// for the second-level HTLC output to be spent, and for that
// wait for the second-level HTLC output to be spent, and for that
// transaction itself to confirm.
if h.htlcResolution.SignedTimeoutTx != nil {
log.Infof("%T(%v): waiting for nursery to spend CSV delayed "+