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Merge pull request #8950 from ProofOfKeags/refactor/lnwallet-channel-move-only

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[NANO]: Move definitions into their own file
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Oliver Gugger 2024-07-31 06:53:19 -06:00 • committed by GitHub
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4 changed files with 481 additions and 462 deletions
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462
lnwallet/channel.go
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@ -2,7 +2,6 @@ package lnwallet
import (
"bytes"
"container/list"
"crypto/sha256"
"errors"
"fmt"
@ -168,220 +167,6 @@ func (e *ErrCommitSyncLocalDataLoss) Error() string {
// payments requested by the wallet/daemon.
type PaymentHash [32]byte
// updateType is the exact type of an entry within the shared HTLC log.
type updateType uint8
const (
// Add is an update type that adds a new HTLC entry into the log.
// Either side can add a new pending HTLC by adding a new Add entry
// into their update log.
Add updateType = iota
// Fail is an update type which removes a prior HTLC entry from the
// log. Adding a Fail entry to one's log will modify the _remote_
// party's update log once a new commitment view has been evaluated
// which contains the Fail entry.
Fail
// MalformedFail is an update type which removes a prior HTLC entry
// from the log. Adding a MalformedFail entry to one's log will modify
// the _remote_ party's update log once a new commitment view has been
// evaluated which contains the MalformedFail entry. The difference
// from Fail type lie in the different data we have to store.
MalformedFail
// Settle is an update type which settles a prior HTLC crediting the
// balance of the receiving node. Adding a Settle entry to a log will
// result in the settle entry being removed on the log as well as the
// original add entry from the remote party's log after the next state
// transition.
Settle
// FeeUpdate is an update type sent by the channel initiator that
// updates the fee rate used when signing the commitment transaction.
FeeUpdate
)
// String returns a human readable string that uniquely identifies the target
// update type.
func (u updateType) String() string {
switch u {
case Add:
return "Add"
case Fail:
return "Fail"
case MalformedFail:
return "MalformedFail"
case Settle:
return "Settle"
case FeeUpdate:
return "FeeUpdate"
default:
return "<unknown type>"
}
}
// PaymentDescriptor represents a commitment state update which either adds,
// settles, or removes an HTLC. PaymentDescriptors encapsulate all necessary
// metadata w.r.t to an HTLC, and additional data pairing a settle message to
// the original added HTLC.
//
// TODO(roasbeef): LogEntry interface??
// - need to separate attrs for cancel/add/settle/feeupdate
type PaymentDescriptor struct {
// RHash is the payment hash for this HTLC. The HTLC can be settled iff
// the preimage to this hash is presented.
RHash PaymentHash
// RPreimage is the preimage that settles the HTLC pointed to within the
// log by the ParentIndex.
RPreimage PaymentHash
// Timeout is the absolute timeout in blocks, after which this HTLC
// expires.
Timeout uint32
// Amount is the HTLC amount in milli-satoshis.
Amount lnwire.MilliSatoshi
// LogIndex is the log entry number that his HTLC update has within the
// log. Depending on if IsIncoming is true, this is either an entry the
// remote party added, or one that we added locally.
LogIndex uint64
// HtlcIndex is the index within the main update log for this HTLC.
// Entries within the log of type Add will have this field populated,
// as other entries will point to the entry via this counter.
//
// NOTE: This field will only be populate if EntryType is Add.
HtlcIndex uint64
// ParentIndex is the HTLC index of the entry that this update settles or
// times out.
//
// NOTE: This field will only be populate if EntryType is Fail or
// Settle.
ParentIndex uint64
// SourceRef points to an Add update in a forwarding package owned by
// this channel.
//
// NOTE: This field will only be populated if EntryType is Fail or
// Settle.
SourceRef *channeldb.AddRef
// DestRef points to a Fail/Settle update in another link's forwarding
// package.
//
// NOTE: This field will only be populated if EntryType is Fail or
// Settle, and the forwarded Add successfully included in an outgoing
// link's commitment txn.
DestRef *channeldb.SettleFailRef
// OpenCircuitKey references the incoming Chan/HTLC ID of an Add HTLC
// packet delivered by the switch.
//
// NOTE: This field is only populated for payment descriptors in the
// *local* update log, and if the Add packet was delivered by the
// switch.
OpenCircuitKey *models.CircuitKey
// ClosedCircuitKey references the incoming Chan/HTLC ID of the Add HTLC
// that opened the circuit.
//
// NOTE: This field is only populated for payment descriptors in the
// *local* update log, and if settle/fails have a committed circuit in
// the circuit map.
ClosedCircuitKey *models.CircuitKey
// localOutputIndex is the output index of this HTLc output in the
// commitment transaction of the local node.
//
// NOTE: If the output is dust from the PoV of the local commitment
// chain, then this value will be -1.
localOutputIndex int32
// remoteOutputIndex is the output index of this HTLC output in the
// commitment transaction of the remote node.
//
// NOTE: If the output is dust from the PoV of the remote commitment
// chain, then this value will be -1.
remoteOutputIndex int32
// sig is the signature for the second-level HTLC transaction that
// spends the version of this HTLC on the commitment transaction of the
// local node. This signature is generated by the remote node and
// stored by the local node in the case that local node needs to
// broadcast their commitment transaction.
sig input.Signature
// addCommitHeight[Remote|Local] encodes the height of the commitment
// which included this HTLC on either the remote or local commitment
// chain. This value is used to determine when an HTLC is fully
// "locked-in".
addCommitHeightRemote uint64
addCommitHeightLocal uint64
// removeCommitHeight[Remote|Local] encodes the height of the
// commitment which removed the parent pointer of this
// PaymentDescriptor either due to a timeout or a settle. Once both
// these heights are below the tail of both chains, the log entries can
// safely be removed.
removeCommitHeightRemote uint64
removeCommitHeightLocal uint64
// OnionBlob is an opaque blob which is used to complete multi-hop
// routing.
//
// NOTE: Populated only on add payment descriptor entry types.
OnionBlob []byte
// ShaOnionBlob is a sha of the onion blob.
//
// NOTE: Populated only in payment descriptor with MalformedFail type.
ShaOnionBlob [sha256.Size]byte
// FailReason stores the reason why a particular payment was canceled.
//
// NOTE: Populate only in fail payment descriptor entry types.
FailReason []byte
// FailCode stores the code why a particular payment was canceled.
//
// NOTE: Populated only in payment descriptor with MalformedFail type.
FailCode lnwire.FailCode
// [our|their|]PkScript are the raw public key scripts that encodes the
// redemption rules for this particular HTLC. These fields will only be
// populated iff the EntryType of this PaymentDescriptor is Add.
// ourPkScript is the ourPkScript from the context of our local
// commitment chain. theirPkScript is the latest pkScript from the
// context of the remote commitment chain.
//
// NOTE: These values may change within the logs themselves, however,
// they'll stay consistent within the commitment chain entries
// themselves.
ourPkScript []byte
ourWitnessScript []byte
theirPkScript []byte
theirWitnessScript []byte
// EntryType denotes the exact type of the PaymentDescriptor. In the
// case of a Timeout, or Settle type, then the Parent field will point
// into the log to the HTLC being modified.
EntryType updateType
// isForwarded denotes if an incoming HTLC has been forwarded to any
// possible upstream peers in the route.
isForwarded bool
// BlindingPoint is an optional ephemeral key used in route blinding.
// This value is set for nodes that are relaying payments inside of a
// blinded route (ie, not the introduction node) from update_add_htlc's
// TLVs.
BlindingPoint lnwire.BlindingPointRecord
}
// PayDescsFromRemoteLogUpdates converts a slice of LogUpdates received from the
// remote peer into PaymentDescriptors to inform a link's forwarding decisions.
//
@ -983,253 +768,6 @@ func (lc *LightningChannel) diskCommitToMemCommit(isLocal bool,
return commit, nil
}
// commitmentChain represents a chain of unrevoked commitments. The tail of the
// chain is the latest fully signed, yet unrevoked commitment. Two chains are
// tracked, one for the local node, and another for the remote node. New
// commitments we create locally extend the remote node's chain, and vice
// versa. Commitment chains are allowed to grow to a bounded length, after
// which the tail needs to be "dropped" before new commitments can be received.
// The tail is "dropped" when the owner of the chain sends a revocation for the
// previous tail.
type commitmentChain struct {
// commitments is a linked list of commitments to new states. New
// commitments are added to the end of the chain with increase height.
// Once a commitment transaction is revoked, the tail is incremented,
// freeing up the revocation window for new commitments.
commitments *list.List
}
// newCommitmentChain creates a new commitment chain.
func newCommitmentChain() *commitmentChain {
return &commitmentChain{
commitments: list.New(),
}
}
// addCommitment extends the commitment chain by a single commitment. This
// added commitment represents a state update proposed by either party. Once
// the commitment prior to this commitment is revoked, the commitment becomes
// the new defacto state within the channel.
func (s *commitmentChain) addCommitment(c *commitment) {
s.commitments.PushBack(c)
}
// advanceTail reduces the length of the commitment chain by one. The tail of
// the chain should be advanced once a revocation for the lowest unrevoked
// commitment in the chain is received.
func (s *commitmentChain) advanceTail() {
s.commitments.Remove(s.commitments.Front())
}
// tip returns the latest commitment added to the chain.
func (s *commitmentChain) tip() *commitment {
return s.commitments.Back().Value.(*commitment)
}
// tail returns the lowest unrevoked commitment transaction in the chain.
func (s *commitmentChain) tail() *commitment {
return s.commitments.Front().Value.(*commitment)
}
// hasUnackedCommitment returns true if the commitment chain has more than one
// entry. The tail of the commitment chain has been ACKed by revoking all prior
// commitments, but any subsequent commitments have not yet been ACKed.
func (s *commitmentChain) hasUnackedCommitment() bool {
return s.commitments.Front() != s.commitments.Back()
}
// updateLog is an append-only log that stores updates to a node's commitment
// chain. This structure can be seen as the "mempool" within Lightning where
// changes are stored before they're committed to the chain. Once an entry has
// been committed in both the local and remote commitment chain, then it can be
// removed from this log.
//
// TODO(roasbeef): create lightning package, move commitment and update to
// package?
// - also move state machine, separate from lnwallet package
// - possible embed updateLog within commitmentChain.
type updateLog struct {
// logIndex is a monotonically increasing integer that tracks the total
// number of update entries ever applied to the log. When sending new
// commitment states, we include all updates up to this index.
logIndex uint64
// htlcCounter is a monotonically increasing integer that tracks the
// total number of offered HTLC's by the owner of this update log,
// hence the `Add` update type. We use a distinct index for this
// purpose, as update's that remove entries from the log will be
// indexed using this counter.
htlcCounter uint64
// List is the updatelog itself, we embed this value so updateLog has
// access to all the method of a list.List.
*list.List
// updateIndex maps a `logIndex` to a particular update entry. It
// deals with the four update types:
// `Fail|MalformedFail|Settle|FeeUpdate`
updateIndex map[uint64]*list.Element
// htlcIndex maps a `htlcCounter` to an offered HTLC entry, hence the
// `Add` update.
htlcIndex map[uint64]*list.Element
// modifiedHtlcs is a set that keeps track of all the current modified
// htlcs, hence update types `Fail|MalformedFail|Settle`. 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.
func newUpdateLog(logIndex, htlcCounter uint64) *updateLog {
return &updateLog{
List: list.New(),
updateIndex: make(map[uint64]*list.Element),
htlcIndex: make(map[uint64]*list.Element),
logIndex: logIndex,
htlcCounter: htlcCounter,
modifiedHtlcs: make(map[uint64]struct{}),
}
}
// restoreHtlc will "restore" a prior HTLC to the updateLog. We say restore as
// this method is intended to be used when re-covering a prior commitment
// state. This function differs from appendHtlc in that it won't increment
// either of log's counters. If the HTLC is already present, then it is
// ignored.
func (u *updateLog) restoreHtlc(pd *PaymentDescriptor) {
if _, ok := u.htlcIndex[pd.HtlcIndex]; ok {
return
}
u.htlcIndex[pd.HtlcIndex] = u.PushBack(pd)
}
// appendUpdate appends a new update to the tip of the updateLog. The entry is
// also added to index accordingly.
func (u *updateLog) appendUpdate(pd *PaymentDescriptor) {
u.updateIndex[u.logIndex] = u.PushBack(pd)
u.logIndex++
}
// restoreUpdate appends a new update to the tip of the updateLog. The entry is
// also added to index accordingly. This function differs from appendUpdate in
// that it won't increment the log index counter.
func (u *updateLog) restoreUpdate(pd *PaymentDescriptor) {
u.updateIndex[pd.LogIndex] = u.PushBack(pd)
}
// appendHtlc appends a new HTLC offer to the tip of the update log. The entry
// is also added to the offer index accordingly.
func (u *updateLog) appendHtlc(pd *PaymentDescriptor) {
u.htlcIndex[u.htlcCounter] = u.PushBack(pd)
u.htlcCounter++
u.logIndex++
}
// lookupHtlc attempts to look up an offered HTLC according to its offer
// index. If the entry isn't found, then a nil pointer is returned.
func (u *updateLog) lookupHtlc(i uint64) *PaymentDescriptor {
htlc, ok := u.htlcIndex[i]
if !ok {
return nil
}
return htlc.Value.(*PaymentDescriptor)
}
// remove attempts to remove an entry from the update log. If the entry is
// found, then the entry will be removed from the update log and index.
func (u *updateLog) removeUpdate(i uint64) {
entry := u.updateIndex[i]
u.Remove(entry)
delete(u.updateIndex, i)
}
// removeHtlc attempts to remove an HTLC offer form the update log. If the
// entry is found, then the entry will be removed from both the main log and
// the offer index.
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
// have been removed from the point-of-view of the tail of both chains. The
// entries which timeout/settle HTLCs are also removed.
func compactLogs(ourLog, theirLog *updateLog,
localChainTail, remoteChainTail uint64) {
compactLog := func(logA, logB *updateLog) {
var nextA *list.Element
for e := logA.Front(); e != nil; e = nextA {
// Assign next iteration element at top of loop because
// we may remove the current element from the list,
// which can change the iterated sequence.
nextA = e.Next()
htlc := e.Value.(*PaymentDescriptor)
// We skip Adds, as they will be removed along with the
// fail/settles below.
if htlc.EntryType == Add {
continue
}
// If the HTLC hasn't yet been removed from either
// chain, the skip it.
if htlc.removeCommitHeightRemote == 0 ||
htlc.removeCommitHeightLocal == 0 {
continue
}
// Otherwise if the height of the tail of both chains
// is at least the height in which the HTLC was
// removed, then evict the settle/timeout entry along
// with the original add entry.
if remoteChainTail >= htlc.removeCommitHeightRemote &&
localChainTail >= htlc.removeCommitHeightLocal {
// Fee updates have no parent htlcs, so we only
// remove the update itself.
if htlc.EntryType == FeeUpdate {
logA.removeUpdate(htlc.LogIndex)
continue
}
// The other types (fail/settle) do have a
// parent HTLC, so we'll remove that HTLC from
// the other log.
logA.removeUpdate(htlc.LogIndex)
logB.removeHtlc(htlc.ParentIndex)
}
}
}
compactLog(ourLog, theirLog)
compactLog(theirLog, ourLog)
}
// LightningChannel implements the state machine which corresponds to the
// current commitment protocol wire spec. The state machine implemented allows
// for asynchronous fully desynchronized, batched+pipelined updates to

60
lnwallet/commitment_chain.go Normal file
View file

@ -0,0 +1,60 @@
package lnwallet
import "container/list"
// commitmentChain represents a chain of unrevoked commitments. The tail of the
// chain is the latest fully signed, yet unrevoked commitment. Two chains are
// tracked, one for the local node, and another for the remote node. New
// commitments we create locally extend the remote node's chain, and vice
// versa. Commitment chains are allowed to grow to a bounded length, after
// which the tail needs to be "dropped" before new commitments can be received.
// The tail is "dropped" when the owner of the chain sends a revocation for the
// previous tail.
type commitmentChain struct {
// commitments is a linked list of commitments to new states. New
// commitments are added to the end of the chain with increase height.
// Once a commitment transaction is revoked, the tail is incremented,
// freeing up the revocation window for new commitments.
commitments *list.List
}
// newCommitmentChain creates a new commitment chain.
func newCommitmentChain() *commitmentChain {
return &commitmentChain{
commitments: list.New(),
}
}
// addCommitment extends the commitment chain by a single commitment. This
// added commitment represents a state update proposed by either party. Once
// the commitment prior to this commitment is revoked, the commitment becomes
// the new defacto state within the channel.
func (s *commitmentChain) addCommitment(c *commitment) {
s.commitments.PushBack(c)
}
// advanceTail reduces the length of the commitment chain by one. The tail of
// the chain should be advanced once a revocation for the lowest unrevoked
// commitment in the chain is received.
func (s *commitmentChain) advanceTail() {
s.commitments.Remove(s.commitments.Front())
}
// tip returns the latest commitment added to the chain.
func (s *commitmentChain) tip() *commitment {
//nolint:forcetypeassert
return s.commitments.Back().Value.(*commitment)
}
// tail returns the lowest unrevoked commitment transaction in the chain.
func (s *commitmentChain) tail() *commitment {
//nolint:forcetypeassert
return s.commitments.Front().Value.(*commitment)
}
// hasUnackedCommitment returns true if the commitment chain has more than one
// entry. The tail of the commitment chain has been ACKed by revoking all prior
// commitments, but any subsequent commitments have not yet been ACKed.
func (s *commitmentChain) hasUnackedCommitment() bool {
return s.commitments.Front() != s.commitments.Back()
}

224
lnwallet/payment_descriptor.go Normal file
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@ -0,0 +1,224 @@
package lnwallet
import (
"crypto/sha256"
"github.com/lightningnetwork/lnd/channeldb"
"github.com/lightningnetwork/lnd/channeldb/models"
"github.com/lightningnetwork/lnd/input"
"github.com/lightningnetwork/lnd/lnwire"
)
// updateType is the exact type of an entry within the shared HTLC log.
type updateType uint8
const (
// Add is an update type that adds a new HTLC entry into the log.
// Either side can add a new pending HTLC by adding a new Add entry
// into their update log.
Add updateType = iota
// Fail is an update type which removes a prior HTLC entry from the
// log. Adding a Fail entry to one's log will modify the _remote_
// party's update log once a new commitment view has been evaluated
// which contains the Fail entry.
Fail
// MalformedFail is an update type which removes a prior HTLC entry
// from the log. Adding a MalformedFail entry to one's log will modify
// the _remote_ party's update log once a new commitment view has been
// evaluated which contains the MalformedFail entry. The difference
// from Fail type lie in the different data we have to store.
MalformedFail
// Settle is an update type which settles a prior HTLC crediting the
// balance of the receiving node. Adding a Settle entry to a log will
// result in the settle entry being removed on the log as well as the
// original add entry from the remote party's log after the next state
// transition.
Settle
// FeeUpdate is an update type sent by the channel initiator that
// updates the fee rate used when signing the commitment transaction.
FeeUpdate
)
// String returns a human readable string that uniquely identifies the target
// update type.
func (u updateType) String() string {
switch u {
case Add:
return "Add"
case Fail:
return "Fail"
case MalformedFail:
return "MalformedFail"
case Settle:
return "Settle"
case FeeUpdate:
return "FeeUpdate"
default:
return "<unknown type>"
}
}
// PaymentDescriptor represents a commitment state update which either adds,
// settles, or removes an HTLC. PaymentDescriptors encapsulate all necessary
// metadata w.r.t to an HTLC, and additional data pairing a settle message to
// the original added HTLC.
//
// TODO(roasbeef): LogEntry interface??
// - need to separate attrs for cancel/add/settle/feeupdate
type PaymentDescriptor struct {
// RHash is the payment hash for this HTLC. The HTLC can be settled iff
// the preimage to this hash is presented.
RHash PaymentHash
// RPreimage is the preimage that settles the HTLC pointed to within the
// log by the ParentIndex.
RPreimage PaymentHash
// Timeout is the absolute timeout in blocks, after which this HTLC
// expires.
Timeout uint32
// Amount is the HTLC amount in milli-satoshis.
Amount lnwire.MilliSatoshi
// LogIndex is the log entry number that his HTLC update has within the
// log. Depending on if IsIncoming is true, this is either an entry the
// remote party added, or one that we added locally.
LogIndex uint64
// HtlcIndex is the index within the main update log for this HTLC.
// Entries within the log of type Add will have this field populated,
// as other entries will point to the entry via this counter.
//
// NOTE: This field will only be populate if EntryType is Add.
HtlcIndex uint64
// ParentIndex is the HTLC index of the entry that this update settles
// or times out.
//
// NOTE: This field will only be populate if EntryType is Fail or
// Settle.
ParentIndex uint64
// SourceRef points to an Add update in a forwarding package owned by
// this channel.
//
// NOTE: This field will only be populated if EntryType is Fail or
// Settle.
SourceRef *channeldb.AddRef
// DestRef points to a Fail/Settle update in another link's forwarding
// package.
//
// NOTE: This field will only be populated if EntryType is Fail or
// Settle, and the forwarded Add successfully included in an outgoing
// link's commitment txn.
DestRef *channeldb.SettleFailRef
// OpenCircuitKey references the incoming Chan/HTLC ID of an Add HTLC
// packet delivered by the switch.
//
// NOTE: This field is only populated for payment descriptors in the
// *local* update log, and if the Add packet was delivered by the
// switch.
OpenCircuitKey *models.CircuitKey
// ClosedCircuitKey references the incoming Chan/HTLC ID of the Add HTLC
// that opened the circuit.
//
// NOTE: This field is only populated for payment descriptors in the
// *local* update log, and if settle/fails have a committed circuit in
// the circuit map.
ClosedCircuitKey *models.CircuitKey
// localOutputIndex is the output index of this HTLc output in the
// commitment transaction of the local node.
//
// NOTE: If the output is dust from the PoV of the local commitment
// chain, then this value will be -1.
localOutputIndex int32
// remoteOutputIndex is the output index of this HTLC output in the
// commitment transaction of the remote node.
//
// NOTE: If the output is dust from the PoV of the remote commitment
// chain, then this value will be -1.
remoteOutputIndex int32
// sig is the signature for the second-level HTLC transaction that
// spends the version of this HTLC on the commitment transaction of the
// local node. This signature is generated by the remote node and
// stored by the local node in the case that local node needs to
// broadcast their commitment transaction.
sig input.Signature
// addCommitHeight[Remote|Local] encodes the height of the commitment
// which included this HTLC on either the remote or local commitment
// chain. This value is used to determine when an HTLC is fully
// "locked-in".
addCommitHeightRemote uint64
addCommitHeightLocal uint64
// removeCommitHeight[Remote|Local] encodes the height of the
// commitment which removed the parent pointer of this
// PaymentDescriptor either due to a timeout or a settle. Once both
// these heights are below the tail of both chains, the log entries can
// safely be removed.
removeCommitHeightRemote uint64
removeCommitHeightLocal uint64
// OnionBlob is an opaque blob which is used to complete multi-hop
// routing.
//
// NOTE: Populated only on add payment descriptor entry types.
OnionBlob []byte
// ShaOnionBlob is a sha of the onion blob.
//
// NOTE: Populated only in payment descriptor with MalformedFail type.
ShaOnionBlob [sha256.Size]byte
// FailReason stores the reason why a particular payment was canceled.
//
// NOTE: Populate only in fail payment descriptor entry types.
FailReason []byte
// FailCode stores the code why a particular payment was canceled.
//
// NOTE: Populated only in payment descriptor with MalformedFail type.
FailCode lnwire.FailCode
// [our|their|]PkScript are the raw public key scripts that encodes the
// redemption rules for this particular HTLC. These fields will only be
// populated iff the EntryType of this PaymentDescriptor is Add.
// ourPkScript is the ourPkScript from the context of our local
// commitment chain. theirPkScript is the latest pkScript from the
// context of the remote commitment chain.
//
// NOTE: These values may change within the logs themselves, however,
// they'll stay consistent within the commitment chain entries
// themselves.
ourPkScript []byte
ourWitnessScript []byte
theirPkScript []byte
theirWitnessScript []byte
// EntryType denotes the exact type of the PaymentDescriptor. In the
// case of a Timeout, or Settle type, then the Parent field will point
// into the log to the HTLC being modified.
EntryType updateType
// isForwarded denotes if an incoming HTLC has been forwarded to any
// possible upstream peers in the route.
isForwarded bool
// BlindingPoint is an optional ephemeral key used in route blinding.
// This value is set for nodes that are relaying payments inside of a
// blinded route (ie, not the introduction node) from update_add_htlc's
// TLVs.
BlindingPoint lnwire.BlindingPointRecord
}

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lnwallet/update_log.go Normal file
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package lnwallet
import "container/list"
// updateLog is an append-only log that stores updates to a node's commitment
// chain. This structure can be seen as the "mempool" within Lightning where
// changes are stored before they're committed to the chain. Once an entry has
// been committed in both the local and remote commitment chain, then it can be
// removed from this log.
//
// TODO(roasbeef): create lightning package, move commitment and update to
// package?
// - also move state machine, separate from lnwallet package
// - possible embed updateLog within commitmentChain.
type updateLog struct {
// logIndex is a monotonically increasing integer that tracks the total
// number of update entries ever applied to the log. When sending new
// commitment states, we include all updates up to this index.
logIndex uint64
// htlcCounter is a monotonically increasing integer that tracks the
// total number of offered HTLC's by the owner of this update log,
// hence the `Add` update type. We use a distinct index for this
// purpose, as update's that remove entries from the log will be
// indexed using this counter.
htlcCounter uint64
// List is the updatelog itself, we embed this value so updateLog has
// access to all the method of a list.List.
*list.List
// updateIndex maps a `logIndex` to a particular update entry. It
// deals with the four update types:
// `Fail|MalformedFail|Settle|FeeUpdate`
updateIndex map[uint64]*list.Element
// htlcIndex maps a `htlcCounter` to an offered HTLC entry, hence the
// `Add` update.
htlcIndex map[uint64]*list.Element
// modifiedHtlcs is a set that keeps track of all the current modified
// htlcs, hence update types `Fail|MalformedFail|Settle`. 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.
func newUpdateLog(logIndex, htlcCounter uint64) *updateLog {
return &updateLog{
List: list.New(),
updateIndex: make(map[uint64]*list.Element),
htlcIndex: make(map[uint64]*list.Element),
logIndex: logIndex,
htlcCounter: htlcCounter,
modifiedHtlcs: make(map[uint64]struct{}),
}
}
// restoreHtlc will "restore" a prior HTLC to the updateLog. We say restore as
// this method is intended to be used when re-covering a prior commitment
// state. This function differs from appendHtlc in that it won't increment
// either of log's counters. If the HTLC is already present, then it is
// ignored.
func (u *updateLog) restoreHtlc(pd *PaymentDescriptor) {
if _, ok := u.htlcIndex[pd.HtlcIndex]; ok {
return
}
u.htlcIndex[pd.HtlcIndex] = u.PushBack(pd)
}
// appendUpdate appends a new update to the tip of the updateLog. The entry is
// also added to index accordingly.
func (u *updateLog) appendUpdate(pd *PaymentDescriptor) {
u.updateIndex[u.logIndex] = u.PushBack(pd)
u.logIndex++
}
// restoreUpdate appends a new update to the tip of the updateLog. The entry is
// also added to index accordingly. This function differs from appendUpdate in
// that it won't increment the log index counter.
func (u *updateLog) restoreUpdate(pd *PaymentDescriptor) {
u.updateIndex[pd.LogIndex] = u.PushBack(pd)
}
// appendHtlc appends a new HTLC offer to the tip of the update log. The entry
// is also added to the offer index accordingly.
func (u *updateLog) appendHtlc(pd *PaymentDescriptor) {
u.htlcIndex[u.htlcCounter] = u.PushBack(pd)
u.htlcCounter++
u.logIndex++
}
// lookupHtlc attempts to look up an offered HTLC according to its offer
// index. If the entry isn't found, then a nil pointer is returned.
func (u *updateLog) lookupHtlc(i uint64) *PaymentDescriptor {
htlc, ok := u.htlcIndex[i]
if !ok {
return nil
}
//nolint:forcetypeassert
return htlc.Value.(*PaymentDescriptor)
}
// remove attempts to remove an entry from the update log. If the entry is
// found, then the entry will be removed from the update log and index.
func (u *updateLog) removeUpdate(i uint64) {
entry := u.updateIndex[i]
u.Remove(entry)
delete(u.updateIndex, i)
}
// removeHtlc attempts to remove an HTLC offer form the update log. If the
// entry is found, then the entry will be removed from both the main log and
// the offer index.
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
// have been removed from the point-of-view of the tail of both chains. The
// entries which timeout/settle HTLCs are also removed.
func compactLogs(ourLog, theirLog *updateLog,
localChainTail, remoteChainTail uint64) {
compactLog := func(logA, logB *updateLog) {
var nextA *list.Element
for e := logA.Front(); e != nil; e = nextA {
// Assign next iteration element at top of loop because
// we may remove the current element from the list,
// which can change the iterated sequence.
nextA = e.Next()
//nolint:forcetypeassert
htlc := e.Value.(*PaymentDescriptor)
// We skip Adds, as they will be removed along with the
// fail/settles below.
if htlc.EntryType == Add {
continue
}
// If the HTLC hasn't yet been removed from either
// chain, the skip it.
if htlc.removeCommitHeightRemote == 0 ||
htlc.removeCommitHeightLocal == 0 {
continue
}
// Otherwise if the height of the tail of both chains
// is at least the height in which the HTLC was
// removed, then evict the settle/timeout entry along
// with the original add entry.
if remoteChainTail >= htlc.removeCommitHeightRemote &&
localChainTail >= htlc.removeCommitHeightLocal {
// Fee updates have no parent htlcs, so we only
// remove the update itself.
if htlc.EntryType == FeeUpdate {
logA.removeUpdate(htlc.LogIndex)
continue
}
// The other types (fail/settle) do have a
// parent HTLC, so we'll remove that HTLC from
// the other log.
logA.removeUpdate(htlc.LogIndex)
logB.removeHtlc(htlc.ParentIndex)
}
}
}
compactLog(ourLog, theirLog)
compactLog(theirLog, ourLog)
}