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Merge pull request #1286 from Roasbeef/prevent-duplicate-htlc-mods

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lnwallet: ensure we reject duplicate fails and settles for HTLCs
This commit is contained in:
Olaoluwa Osuntokun 2018-05-28 12:23:48 -07:00 committed by GitHub
commit 9f358db7c7
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GPG Key ID: 4AEE18F83AFDEB23
2 changed files with 261 additions and 8 deletions
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96
lnwallet/channel.go
View File

@ -825,7 +825,7 @@ func (lc *LightningChannel) extractPayDescs(commitHeight uint64,
return incomingHtlcs, outgoingHtlcs, nil
}
// diskCommitToMemCommit converts tthe on-disk commitment format to our
// diskCommitToMemCommit converts the on-disk commitment format to our
// in-memory commitment format which is needed in order to properly resume
// channel operations after a restart.
func (lc *LightningChannel) diskCommitToMemCommit(isLocal, isPendingCommit bool,
@ -1090,6 +1090,11 @@ type updateLog struct {
// offerIndex is an index that maps the counter for offered HTLC's to
// their list element within the main list.List.
htlcIndex map[uint64]*list.Element
// modifiedHtlcs is a set that keeps track of all the current modified
// htlcs. A modified HTLC is one that's present in the log, and has as
// a pending fail or settle that's attempting to consume it.
modifiedHtlcs map[uint64]struct{}
}
// newUpdateLog creates a new updateLog instance.
@ -1100,6 +1105,7 @@ func newUpdateLog(logIndex, htlcCounter uint64) *updateLog {
htlcIndex: make(map[uint64]*list.Element),
logIndex: logIndex,
htlcCounter: htlcCounter,
modifiedHtlcs: make(map[uint64]struct{}),
}
}
@ -1158,6 +1164,22 @@ func (u *updateLog) removeHtlc(i uint64) {
entry := u.htlcIndex[i]
u.Remove(entry)
delete(u.htlcIndex, i)
delete(u.modifiedHtlcs, i)
}
// htlcHasModification returns true if the HTLC identified by the passed index
// has a pending modification within the log.
func (u *updateLog) htlcHasModification(i uint64) bool {
_, o := u.modifiedHtlcs[i]
return o
}
// markHtlcModified marks an HTLC as modified based on its HTLC index. After a
// call to this method, htlcHasModification will return true until the HTLC is
// removed.
func (u *updateLog) markHtlcModified(i uint64) {
u.modifiedHtlcs[i] = struct{}{}
}
// compactLogs performs garbage collection within the log removing HTLCs which
@ -1509,10 +1531,12 @@ func (lc *LightningChannel) logUpdateToPayDesc(logUpdate *channeldb.LogUpdate,
if !isDustRemote {
theirP2WSH, theirWitnessScript, err := genHtlcScript(
false, false, wireMsg.Expiry, wireMsg.PaymentHash,
remoteCommitKeys)
remoteCommitKeys,
)
if err != nil {
return nil, err
}
pd.theirPkScript = theirP2WSH
pd.theirWitnessScript = theirWitnessScript
}
@ -1571,7 +1595,7 @@ func (lc *LightningChannel) logUpdateToPayDesc(logUpdate *channeldb.LogUpdate,
}
// restoreCommitState will restore the local commitment chain and updateLog
// state to a consistent in-memory representation of the passed dis commitment.
// state to a consistent in-memory representation of the passed disk commitment.
// This method is to be used upon reconnection to our channel counter party.
// Once the connection has been established, we'll prepare our in memory state
// to re-sync states with the remote party, and also verify/extend new proposed
@ -1749,9 +1773,12 @@ func (lc *LightningChannel) restoreStateLogs(
"%v vs %v", payDesc.HtlcIndex,
lc.localUpdateLog.htlcCounter))
}
lc.localUpdateLog.appendHtlc(payDesc)
} else {
lc.localUpdateLog.appendUpdate(payDesc)
lc.remoteUpdateLog.markHtlcModified(payDesc.ParentIndex)
}
}
@ -4353,6 +4380,14 @@ func (lc *LightningChannel) SettleHTLC(preimage [32]byte,
lc.ShortChanID())
}
// Now that we know the HTLC exists, before checking to see if the
// preimage matches, we'll ensure that we haven't already attempted to
// modify the HTLC.
if lc.remoteUpdateLog.htlcHasModification(htlcIndex) {
return fmt.Errorf("HTLC with ID %d has already been settled",
htlcIndex)
}
if htlc.RHash != sha256.Sum256(preimage[:]) {
return fmt.Errorf("Invalid payment preimage %x for hash %x",
preimage[:], htlc.RHash[:])
@ -4371,6 +4406,11 @@ func (lc *LightningChannel) SettleHTLC(preimage [32]byte,
lc.localUpdateLog.appendUpdate(pd)
// With the settle added to our local log, we'll now mark the HTLC as
// modified to prevent ourselves from accidentally attempting a
// duplicate settle.
lc.remoteUpdateLog.markHtlcModified(htlcIndex)
return nil
}
@ -4388,6 +4428,14 @@ func (lc *LightningChannel) ReceiveHTLCSettle(preimage [32]byte, htlcIndex uint6
lc.ShortChanID())
}
// Now that we know the HTLC exists, before checking to see if the
// preimage matches, we'll ensure that they haven't already attempted
// to modify the HTLC.
if lc.localUpdateLog.htlcHasModification(htlcIndex) {
return fmt.Errorf("HTLC with ID %d has already been settled",
htlcIndex)
}
if htlc.RHash != sha256.Sum256(preimage[:]) {
return fmt.Errorf("Invalid payment preimage %x for hash %x",
preimage[:], htlc.RHash[:])
@ -4403,6 +4451,12 @@ func (lc *LightningChannel) ReceiveHTLCSettle(preimage [32]byte, htlcIndex uint6
}
lc.remoteUpdateLog.appendUpdate(pd)
// With the settle added to the remote log, we'll now mark the HTLC as
// modified to prevent the remote party from accidentally attempting a
// duplicate settle.
lc.localUpdateLog.markHtlcModified(htlcIndex)
return nil
}
@ -4442,6 +4496,13 @@ func (lc *LightningChannel) FailHTLC(htlcIndex uint64, reason []byte,
lc.ShortChanID())
}
// Now that we know the HTLC exists, we'll ensure that we haven't
// already attempted to fail the HTLC.
if lc.remoteUpdateLog.htlcHasModification(htlcIndex) {
return fmt.Errorf("HTLC with ID %d has already been failed",
htlcIndex)
}
pd := &PaymentDescriptor{
Amount: htlc.Amount,
RHash: htlc.RHash,
@ -4456,6 +4517,11 @@ func (lc *LightningChannel) FailHTLC(htlcIndex uint64, reason []byte,
lc.localUpdateLog.appendUpdate(pd)
// With the fail added to the remote log, we'll now mark the HTLC as
// modified to prevent ourselves from accidentally attempting a
// duplicate fail.
lc.remoteUpdateLog.markHtlcModified(htlcIndex)
return nil
}
@ -4482,6 +4548,13 @@ func (lc *LightningChannel) MalformedFailHTLC(htlcIndex uint64,
lc.ShortChanID())
}
// Now that we know the HTLC exists, we'll ensure that we haven't
// already attempted to fail the HTLC.
if lc.remoteUpdateLog.htlcHasModification(htlcIndex) {
return fmt.Errorf("HTLC with ID %d has already been failed",
htlcIndex)
}
pd := &PaymentDescriptor{
Amount: htlc.Amount,
RHash: htlc.RHash,
@ -4495,6 +4568,11 @@ func (lc *LightningChannel) MalformedFailHTLC(htlcIndex uint64,
lc.localUpdateLog.appendUpdate(pd)
// With the fail added to the remote log, we'll now mark the HTLC as
// modified to prevent ourselves from accidentally attempting a
// duplicate fail.
lc.remoteUpdateLog.markHtlcModified(htlcIndex)
return nil
}
@ -4515,6 +4593,13 @@ func (lc *LightningChannel) ReceiveFailHTLC(htlcIndex uint64, reason []byte,
lc.ShortChanID())
}
// Now that we know the HTLC exists, we'll ensure that they haven't
// already attempted to fail the HTLC.
if lc.localUpdateLog.htlcHasModification(htlcIndex) {
return fmt.Errorf("HTLC with ID %d has already been failed",
htlcIndex)
}
pd := &PaymentDescriptor{
Amount: htlc.Amount,
RHash: htlc.RHash,
@ -4526,6 +4611,11 @@ func (lc *LightningChannel) ReceiveFailHTLC(htlcIndex uint64, reason []byte,
lc.remoteUpdateLog.appendUpdate(pd)
// With the fail added to the remote log, we'll now mark the HTLC as
// modified to prevent ourselves from accidentally attempting a
// duplicate fail.
lc.localUpdateLog.markHtlcModified(htlcIndex)
return nil
}

163
lnwallet/channel_test.go
View File

@ -5342,3 +5342,166 @@ func TestChannelRestoreUpdateLogsFailedHTLC(t *testing.T) {
assertInLogs(t, aliceChannel, 0, 0, 0, 0)
restoreAndAssert(t, aliceChannel, 0, 0, 0, 0)
}
// TestDuplicateFailRejection tests that if either party attempts to fail an
// HTLC twice, then we'll reject the second fail attempt.
func TestDuplicateFailRejection(t *testing.T) {
t.Parallel()
aliceChannel, bobChannel, cleanUp, err := CreateTestChannels()
if err != nil {
t.Fatalf("unable to create test channels: %v", err)
}
defer cleanUp()
// First, we'll add an HTLC from Alice to Bob, and lock it in for both
// parties.
htlcAmount := lnwire.NewMSatFromSatoshis(20000)
htlcAlice, _ := createHTLC(0, htlcAmount)
if _, err := aliceChannel.AddHTLC(htlcAlice, nil); err != nil {
t.Fatalf("alice unable to add htlc: %v", err)
}
_, err = bobChannel.ReceiveHTLC(htlcAlice)
if err != nil {
t.Fatalf("unable to recv htlc: %v", err)
}
if err := forceStateTransition(aliceChannel, bobChannel); err != nil {
t.Fatalf("unable to complete state update: %v", err)
}
// With the HTLC locked in, we'll now have Bob fail the HTLC back to
// Alice.
err = bobChannel.FailHTLC(0, []byte("failreason"), nil, nil, nil)
if err != nil {
t.Fatalf("unable to cancel HTLC: %v", err)
}
if err := aliceChannel.ReceiveFailHTLC(0, []byte("bad")); err != nil {
t.Fatalf("unable to recv htlc cancel: %v", err)
}
// If we attempt to fail it AGAIN, then both sides should reject this
// second failure attempt.
err = bobChannel.FailHTLC(0, []byte("failreason"), nil, nil, nil)
if err == nil {
t.Fatalf("duplicate HTLC failure attempt should have failed")
}
if err := aliceChannel.ReceiveFailHTLC(0, []byte("bad")); err == nil {
t.Fatalf("duplicate HTLC failure attempt should have failed")
}
// We'll now have Bob sign a new commitment to lock in the HTLC fail
// for Alice.
_, _, err = bobChannel.SignNextCommitment()
if err != nil {
t.Fatalf("unable to sign commit: %v", err)
}
// We'll now force a restart for Bob and Alice, so we can test the
// persistence related portion of this assertion.
bobChannel, err = restartChannel(bobChannel)
if err != nil {
t.Fatalf("unable to restart channel: %v", err)
}
defer bobChannel.Stop()
aliceChannel, err = restartChannel(aliceChannel)
if err != nil {
t.Fatalf("unable to restart channel: %v", err)
}
defer aliceChannel.Stop()
// If we try to fail the same HTLC again, then we should get an error.
err = bobChannel.FailHTLC(0, []byte("failreason"), nil, nil, nil)
if err == nil {
t.Fatalf("duplicate HTLC failure attempt should have failed")
}
// Alice on the other hand should accept the failure again, as she
// dropped all items in the logs which weren't committed.
if err := aliceChannel.ReceiveFailHTLC(0, []byte("bad")); err != nil {
t.Fatalf("unable to recv htlc cancel: %v", err)
}
}
// TestDuplicateSettleRejection tests that if either party attempts to settle
// an HTLC twice, then we'll reject the second settle attempt.
func TestDuplicateSettleRejection(t *testing.T) {
t.Parallel()
aliceChannel, bobChannel, cleanUp, err := CreateTestChannels()
if err != nil {
t.Fatalf("unable to create test channels: %v", err)
}
defer cleanUp()
// First, we'll add an HTLC from Alice to Bob, and lock it in for both
// parties.
htlcAmount := lnwire.NewMSatFromSatoshis(20000)
htlcAlice, alicePreimage := createHTLC(0, htlcAmount)
if _, err := aliceChannel.AddHTLC(htlcAlice, nil); err != nil {
t.Fatalf("alice unable to add htlc: %v", err)
}
_, err = bobChannel.ReceiveHTLC(htlcAlice)
if err != nil {
t.Fatalf("unable to recv htlc: %v", err)
}
if err := forceStateTransition(aliceChannel, bobChannel); err != nil {
t.Fatalf("unable to complete state update: %v", err)
}
// With the HTLC locked in, we'll now have Bob settle the HTLC back to
// Alice.
err = bobChannel.SettleHTLC(alicePreimage, uint64(0), nil, nil, nil)
if err != nil {
t.Fatalf("unable to cancel HTLC: %v", err)
}
err = aliceChannel.ReceiveHTLCSettle(alicePreimage, uint64(0))
if err != nil {
t.Fatalf("unable to recv htlc cancel: %v", err)
}
// If we attempt to fail it AGAIN, then both sides should reject this
// second failure attempt.
err = bobChannel.SettleHTLC(alicePreimage, uint64(0), nil, nil, nil)
if err == nil {
t.Fatalf("duplicate HTLC failure attempt should have failed")
}
err = aliceChannel.ReceiveHTLCSettle(alicePreimage, uint64(0))
if err == nil {
t.Fatalf("duplicate HTLC failure attempt should have failed")
}
// We'll now have Bob sign a new commitment to lock in the HTLC fail
// for Alice.
_, _, err = bobChannel.SignNextCommitment()
if err != nil {
t.Fatalf("unable to sign commit: %v", err)
}
// We'll now force a restart for Bob and Alice, so we can test the
// persistence related portion of this assertion.
bobChannel, err = restartChannel(bobChannel)
if err != nil {
t.Fatalf("unable to restart channel: %v", err)
}
defer bobChannel.Stop()
aliceChannel, err = restartChannel(aliceChannel)
if err != nil {
t.Fatalf("unable to restart channel: %v", err)
}
defer aliceChannel.Stop()
// If we try to fail the same HTLC again, then we should get an error.
err = bobChannel.SettleHTLC(alicePreimage, uint64(0), nil, nil, nil)
if err == nil {
t.Fatalf("duplicate HTLC failure attempt should have failed")
}
// Alice on the other hand should accept the failure again, as she
// dropped all items in the logs which weren't committed.
err = aliceChannel.ReceiveHTLCSettle(alicePreimage, uint64(0))
if err != nil {
t.Fatalf("unable to recv htlc cancel: %v", err)
}
}