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lnwallet: populate the output index of an HTLC in ChannelDeltas

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This commit modifies the logic within the state machine to properly
populate the new field of `OutputIndex` which the HTLC stored within a
channel delta.

With this change, in the future we’ll be able to quickly locate a
particular HTLC output in the scenario that the commitment transaction
has been broadcast on-chain and we need to sweep it. Allocating a few
extra bytes on-disk saves us from the guess-and-check logic+code
required otherwise.
This commit is contained in:
Olaoluwa Osuntokun 2016-11-20 23:54:18 -06:00
parent 2d884618aa
commit 188811cf05
No known key found for this signature in database
GPG Key ID: 9CC5B105D03521A2
1 changed files with 59 additions and 26 deletions
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85
lnwallet/channel.go
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@ -34,9 +34,9 @@ const (
// * should be tuned to account for max tx "cost"
MaxPendingPayments = 100
// InitialRevocationWindow is the number of unrevoked commitment
// InitialRevocationWindow is the number of revoked commitment
// transactions allowed within the commitment chain. This value allows
// a greater degree of desynchronization by allowing either parties to
// a greater degree of de-synchronization by allowing either parties to
// extend the other's commitment chain non-interactively, and also
// serves as a flow control mechanism to a degree.
InitialRevocationWindow = 4
@ -105,7 +105,7 @@ type PaymentDescriptor struct {
// log by the ParentIndex.
RPreimage PaymentHash
// Timeout is the absolute timeout in blocks, afterwhich this HTLC
// Timeout is the absolute timeout in blocks, after which this HTLC
// expires.
Timeout uint32
@ -147,6 +147,11 @@ type PaymentDescriptor struct {
// possible upstream peers in the route.
isForwarded bool
settled bool
// pkScript is the raw public key script that encodes the redemption
// rules for this particular HTLC. This field will only be populated
// iff the EntryType of this PaymentDescriptor is Add.
pkScript []byte
}
// commitment represents a commitment to a new state within an active channel.
@ -205,6 +210,22 @@ func (c *commitment) toChannelDelta() (*channeldb.ChannelDelta, error) {
Htlcs: make([]*channeldb.HTLC, 0, numHtlcs),
}
// As we also store the output index of the HTLC for continence
// purposes, we create a small helper function to locate the output
// index of a particular HTLC within the current commitment
// transaction.
locateOutputIndex := func(p *PaymentDescriptor) uint16 {
var idx uint16
for i, txOut := range c.txn.TxOut {
// TODO(roasbeef): duplicated payment hashes...
if bytes.Equal(txOut.PkScript, p.pkScript) {
idx = uint16(i)
break
}
}
return idx
}
for _, htlc := range c.outgoingHTLCs {
h := &channeldb.HTLC{
Incoming: false,
@ -212,6 +233,7 @@ func (c *commitment) toChannelDelta() (*channeldb.ChannelDelta, error) {
RHash: htlc.RHash,
RefundTimeout: htlc.Timeout,
RevocationDelay: 0,
OutputIndex: locateOutputIndex(htlc),
}
delta.Htlcs = append(delta.Htlcs, h)
}
@ -222,6 +244,7 @@ func (c *commitment) toChannelDelta() (*channeldb.ChannelDelta, error) {
RHash: htlc.RHash,
RefundTimeout: htlc.Timeout,
RevocationDelay: 0,
OutputIndex: locateOutputIndex(htlc),
}
delta.Htlcs = append(delta.Htlcs, h)
}
@ -336,7 +359,7 @@ type LightningChannel struct {
// revocationWindowEdge is the edge of the current revocation window.
// New revocations for prior states created by this channel extend the
// edge of this revocation window. The existence of a revocation window
// allows the remote party to initiate new state updates independantly
// allows the remote party to initiate new state updates independently
// until the window is exhausted.
revocationWindowEdge uint64
@ -349,7 +372,7 @@ type LightningChannel struct {
// revocationWindow is a window of revocations sent to use by the
// remote party, allowing us to create new commitment transactions
// until depleated. The revocations don't contain a valid pre-iamge,
// until depleted. The revocations don't contain a valid pre-image,
// only an additional key/hash allowing us to create a new commitment
// transaction for the remote node that they are able to revoke. If
// this slice is empty, then we cannot make any new updates to their
@ -529,7 +552,7 @@ func (lc *LightningChannel) restoreStateLogs() error {
for _, htlc := range lc.channelState.Htlcs {
// TODO(roasbeef): set isForwarded to false for all? need to
// persist state w.r.t to if forwarded or not, or can
// inadvertenly trigger replays
// inadvertently trigger replays
pd := &PaymentDescriptor{
RHash: htlc.RHash,
Timeout: htlc.RefundTimeout,
@ -666,14 +689,16 @@ func (lc *LightningChannel) fetchCommitmentView(remoteChain bool,
return nil, err
}
for _, htlc := range filteredHTLCView.ourUpdates {
if err := lc.addHTLC(commitTx, ourCommitTx, htlc,
revocationHash, delay, false); err != nil {
err := lc.addHTLC(commitTx, ourCommitTx, htlc,
revocationHash, delay, false)
if err != nil {
return nil, err
}
}
for _, htlc := range filteredHTLCView.theirUpdates {
if err := lc.addHTLC(commitTx, ourCommitTx, htlc,
revocationHash, delay, true); err != nil {
err := lc.addHTLC(commitTx, ourCommitTx, htlc,
revocationHash, delay, true)
if err != nil {
return nil, err
}
}
@ -687,7 +712,7 @@ func (lc *LightningChannel) fetchCommitmentView(remoteChain bool,
return nil, err
}
// Sort the transactions according to the agreed upon cannonical
// Sort the transactions according to the agreed upon canonical
// ordering. This lets us skip sending the entire transaction over,
// instead we'll just send signatures.
txsort.InPlaceSort(commitTx)
@ -1407,7 +1432,10 @@ func (lc *LightningChannel) ChannelPoint() *wire.OutPoint {
// addHTLC adds a new HTLC to the passed commitment transaction. One of four
// full scripts will be generated for the HTLC output depending on if the HTLC
// is incoming and if it's being applied to our commitment transaction or that
// of the remote node's.
// of the remote node's. Additionally, in order to be able to efficiently
// locate the added HTLC on the commitment transaction from the
// PaymentDescriptor that generated it, the generated script is stored within
// the descriptor itself.
func (lc *LightningChannel) addHTLC(commitTx *wire.MsgTx, ourCommit bool,
paymentDesc *PaymentDescriptor, revocation [32]byte, delay uint32,
isIncoming bool) error {
@ -1463,6 +1491,10 @@ func (lc *LightningChannel) addHTLC(commitTx *wire.MsgTx, ourCommit bool,
amountPending := int64(paymentDesc.Amount)
commitTx.AddTxOut(wire.NewTxOut(amountPending, htlcP2WSH))
// Store the pkScript of this particular PaymentDescriptor so we can
// quickly locate it within the commitment transaction later.
paymentDesc.pkScript = htlcP2WSH
return nil
}
@ -1470,7 +1502,7 @@ func (lc *LightningChannel) addHTLC(commitTx *wire.MsgTx, ourCommit bool,
// locked-down to initiate a force closure by broadcasting the latest state
// on-chain. The summary includes all the information required to claim all
// rightfully owned outputs.
// TODO(roasbeef): generalize, add HTLC info, revocatio info, etc.
// TODO(roasbeef): generalize, add HTLC info, etc.
type ForceCloseSummary struct {
// CloseTx is the transaction which closed the channel on-chain. If we
// initiate the force close, then this'll be our latest commitment
@ -1487,7 +1519,7 @@ type ForceCloseSummary struct {
SelfOutputMaturity uint32
// SelfOutputSignDesc is a fully populated sign descriptor capable of
// generating a valid signature to swee the self output.
// generating a valid signature to sweep the self output.
SelfOutputSignDesc *SignDescriptor
}
@ -1566,7 +1598,7 @@ func (lc *LightningChannel) ForceClose() (*ForceCloseSummary, error) {
return nil, err
}
// With the necessary information gatehred above, create a new sign
// With the necessary information gathered above, create a new sign
// descriptor which is capable of generating the signature the caller
// needs to sweep this output. The hash cache, and input index are not
// set as the caller will decide these values once sweeping the output.
@ -1599,15 +1631,16 @@ func (lc *LightningChannel) ForceClose() (*ForceCloseSummary, error) {
// InitCooperativeClose initiates a cooperative closure of an active lightning
// channel. This method should only be executed once all pending HTLCs (if any)
// on the channel have been cleared/removed. Upon completion, the source channel
// will shift into the "closing" state, which indicates that all incoming/outgoing
// HTLC requests should be rejected. A signature for the closing transaction,
// and the txid of the closing transaction are returned. The initiator of the
// channel closure should then watch the blockchain for a confirmation of the
// closing transaction before considering the channel terminated. In the case
// of an unresponsive remote party, the initiator can either choose to execute
// a force closure, or backoff for a period of time, and retry the cooperative
// closure.
// on the channel have been cleared/removed. Upon completion, the source
// channel will shift into the "closing" state, which indicates that all
// incoming/outgoing HTLC requests should be rejected. A signature for the
// closing transaction, and the txid of the closing transaction are returned.
// The initiator of the channel closure should then watch the blockchain for a
// confirmation of the closing transaction before considering the channel
// terminated. In the case of an unresponsive remote party, the initiator can
// either choose to execute a force closure, or backoff for a period of time,
// and retry the cooperative closure.
//
// TODO(roasbeef): caller should initiate signal to reject all incoming HTLCs,
// settle any inflight.
func (lc *LightningChannel) InitCooperativeClose() ([]byte, *wire.ShaHash, error) {
@ -1646,11 +1679,11 @@ func (lc *LightningChannel) InitCooperativeClose() ([]byte, *wire.ShaHash, error
// CompleteCooperativeClose completes the cooperative closure of the target
// active lightning channel. This method should be called in response to the
// remote node initating a cooperative channel closure. A fully signed closure
// remote node initiating a cooperative channel closure. A fully signed closure
// transaction is returned. It is the duty of the responding node to broadcast
// a signed+valid closure transaction to the network.
//
// NOTE: The passed remote sig is expected to the a fully complete signature
// NOTE: The passed remote sig is expected to be a fully complete signature
// including the proper sighash byte.
func (lc *LightningChannel) CompleteCooperativeClose(remoteSig []byte) (*wire.MsgTx, error) {
lc.Lock()