lnd.xprv/lnwallet/channel.go

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package lnwallet
import (
"bytes"
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"container/list"
"crypto/sha256"
"fmt"
"runtime"
"sort"
"sync"
"sync/atomic"
"github.com/davecgh/go-spew/spew"
"github.com/lightningnetwork/lnd/chainntnfs"
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"github.com/lightningnetwork/lnd/channeldb"
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"github.com/lightningnetwork/lnd/lnwire"
"github.com/roasbeef/btcd/blockchain"
"github.com/roasbeef/btcd/chaincfg/chainhash"
"encoding/hex"
"github.com/roasbeef/btcd/btcec"
"github.com/roasbeef/btcd/txscript"
"github.com/roasbeef/btcd/wire"
"github.com/roasbeef/btcutil"
"github.com/roasbeef/btcutil/txsort"
)
var zeroHash chainhash.Hash
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var (
// ErrChanClosing is returned when a caller attempts to close a channel
// that has already been closed or is in the process of being closed.
ErrChanClosing = fmt.Errorf("channel is being closed, operation disallowed")
// ErrNoWindow is returned when revocation window is exausted.
ErrNoWindow = fmt.Errorf("unable to sign new commitment, the current" +
" revocation window is exhausted")
// ErrMaxWeightCost is returned when the cost/weight (see segwit)
// exceeds the widely used maximum allowed policy weight limit. In this
// case the commitment transaction can't be propagated through the
// network.
ErrMaxWeightCost = fmt.Errorf("commitment transaction exceed max " +
"available cost")
// ErrMaxHTLCNumber is returned when a proposed HTLC would exceed the
// maximum number of allowed HTLC's if committed in a state transition
ErrMaxHTLCNumber = fmt.Errorf("commitment transaction exceed max " +
"htlc number")
// ErrInsufficientBalance is returned when a proposed HTLC would
// exceed the available balance.
ErrInsufficientBalance = fmt.Errorf("insufficient local balance")
)
// channelState is an enum like type which represents the current state of a
// particular channel.
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// TODO(roasbeef): actually update state
type channelState uint8
const (
// channelPending indicates this channel is still going through the
// funding workflow, and isn't yet open.
channelPending channelState = iota
// channelOpen represents an open, active channel capable of
// sending/receiving HTLCs.
channelOpen
// channelClosing represents a channel which is in the process of being
// closed.
channelClosing
// channelClosed represents a channel which has been fully closed. Note
// that before a channel can be closed, ALL pending HTLCs must be
// settled/removed.
channelClosed
// channelDispute indicates that an un-cooperative closure has been
// detected within the channel.
channelDispute
// channelPendingPayment indicates that there a currently outstanding
// HTLCs within the channel.
channelPendingPayment
)
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// PaymentHash represents the sha256 of a random value. This hash is used to
// uniquely track incoming/outgoing payments within this channel, as well as
// payments requested by the wallet/daemon.
type PaymentHash [32]byte
// UpdateType is the exact type of an entry within the shared HTLC log.
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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.
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Add updateType = iota
// Fail is an update type which removes a prior HTLC entry from the
// log. Adding a Fail entry to ones log will modify the _remote_
// parties update log once a new commitment view has been evaluated
// which contains the Fail entry.
Fail
// 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.
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Settle
)
// 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 Settle:
return "Settle"
default:
return "<unknown type>"
}
}
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// 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
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// the original added HTLC.
//
// TODO(roasbeef): LogEntry interface??
// * need to separate attrs for cancel/add/settle
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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 wthin the
// log by the ParentIndex.
RPreimage PaymentHash
// Timeout is the absolute timeout in blocks, after which this HTLC
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// expires.
Timeout uint32
// Amount is the HTLC amount in milli-satoshis.
Amount lnwire.MilliSatoshi
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// LogIndex is the log entry number that his HTLC update has within the
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// 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.
// Entires 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
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// ParentIndex is the index of the log entry that this HTLC update
// settles or times out.
//
// NOTE: This field will only be populate if EntryType is Fail or
// Settle.
lnwallet: update state machine to the version within the spec This commit updates the internal channel state machine to the one as described within the spec and currently implemented within the rest of the other Lightning implementations. At a high level the following modifications have been made: * When signing we no loner include the index of the remote party’s log that our signature covers. Instead we include ALL of our current updates, but only the updates of the remote party that we’ve ACK’d. * A pending change is considered ACK’d once a revocation message has been received, locking in the changes in the remote party’s commitment transaction. * When sending a new commitment, we remember the index of our log at that point so we can mark that portion of the log as ACK’d once we receive a revocation message from the remote party. * When receiving a new commitment signature, we include ALL of the remote party’s changes that we’ve received but only our set of changes that’ve been ACK’d by the remote party. * Implicitly a revocation message now also implicitly serves to ACK all the changes that were included in the CommitSig message received before it. The resulting change is a rather minor diff. However, with this state machine it’s important to note that the order to sig/revoke messages has been swapped. A proper exchange now looks like the following: * Alice -> Add, Add, Add * Alice -> Sig * Revoke <- Bob * Sig <- Bob * Alice -> Revoke One other thing that’s worth noting is that with this state machine, since what’s included in an update is implicit, both side may need to at times send a new commitment update in the case of a concurrent state transition initiated by both sides. Finally, all counters/indexes have been made 64-bit integers in order to properly match the spec.
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ParentIndex uint64
// 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 comimtnet
// 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 *btcec.Signature
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// 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
lnwallet: update state machine to the version within the spec This commit updates the internal channel state machine to the one as described within the spec and currently implemented within the rest of the other Lightning implementations. At a high level the following modifications have been made: * When signing we no loner include the index of the remote party’s log that our signature covers. Instead we include ALL of our current updates, but only the updates of the remote party that we’ve ACK’d. * A pending change is considered ACK’d once a revocation message has been received, locking in the changes in the remote party’s commitment transaction. * When sending a new commitment, we remember the index of our log at that point so we can mark that portion of the log as ACK’d once we receive a revocation message from the remote party. * When receiving a new commitment signature, we include ALL of the remote party’s changes that we’ve received but only our set of changes that’ve been ACK’d by the remote party. * Implicitly a revocation message now also implicitly serves to ACK all the changes that were included in the CommitSig message received before it. The resulting change is a rather minor diff. However, with this state machine it’s important to note that the order to sig/revoke messages has been swapped. A proper exchange now looks like the following: * Alice -> Add, Add, Add * Alice -> Sig * Revoke <- Bob * Sig <- Bob * Alice -> Revoke One other thing that’s worth noting is that with this state machine, since what’s included in an update is implicit, both side may need to at times send a new commitment update in the case of a concurrent state transition initiated by both sides. Finally, all counters/indexes have been made 64-bit integers in order to properly match the spec.
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// commitment which removed the parent pointer of this
// PaymentDescriptor either due to a timeout or a settle. Once both
// these heights are above the tail of both chains, the log entries can
// safely be removed.
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removeCommitHeightRemote uint64
removeCommitHeightLocal uint64
// Payload is an opaque blob which is used to complete multi-hop
// routing.
Payload []byte
// [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
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}
// commitment represents a commitment to a new state within an active channel.
// New commitments can be initiated by either side. Commitments are ordered
// into a commitment chain, with one existing for both parties. Each side can
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// independently extend the other side's commitment chain, up to a certain
// "revocation window", which once reached, disallows new commitments until
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// the local nodes receives the revocation for the remote node's chain tail.
type commitment struct {
// height represents the commitment height of this commitment, or the
// update number of this commitment.
height uint64
// isOurs indicates whether this is the local or remote node's version of
// the commitment.
isOurs bool
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// [our|their]MessageIndex are indexes into the HTLC log, up to which
// this commitment transaction includes. These indexes allow both sides
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// to independently, and concurrent send create new commitments. Each
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// new commitment sent to the remote party includes an index in the
// shared log which details which of their updates we're including in
// this new commitment.
lnwallet: update state machine to the version within the spec This commit updates the internal channel state machine to the one as described within the spec and currently implemented within the rest of the other Lightning implementations. At a high level the following modifications have been made: * When signing we no loner include the index of the remote party’s log that our signature covers. Instead we include ALL of our current updates, but only the updates of the remote party that we’ve ACK’d. * A pending change is considered ACK’d once a revocation message has been received, locking in the changes in the remote party’s commitment transaction. * When sending a new commitment, we remember the index of our log at that point so we can mark that portion of the log as ACK’d once we receive a revocation message from the remote party. * When receiving a new commitment signature, we include ALL of the remote party’s changes that we’ve received but only our set of changes that’ve been ACK’d by the remote party. * Implicitly a revocation message now also implicitly serves to ACK all the changes that were included in the CommitSig message received before it. The resulting change is a rather minor diff. However, with this state machine it’s important to note that the order to sig/revoke messages has been swapped. A proper exchange now looks like the following: * Alice -> Add, Add, Add * Alice -> Sig * Revoke <- Bob * Sig <- Bob * Alice -> Revoke One other thing that’s worth noting is that with this state machine, since what’s included in an update is implicit, both side may need to at times send a new commitment update in the case of a concurrent state transition initiated by both sides. Finally, all counters/indexes have been made 64-bit integers in order to properly match the spec.
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ourMessageIndex uint64
theirMessageIndex uint64
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// txn is the commitment transaction generated by including any HTLC
// updates whose index are below the two indexes listed above. If this
// commitment is being added to the remote chain, then this txn is
// their version of the commitment transactions. If the local commit
// chain is being modified, the opposite is true.
txn *wire.MsgTx
// sig is a signature for the above commitment transaction.
sig []byte
// [our|their]Balance represents the settled balances at this point
// within the commitment chain. This balance is computed by properly
// evaluating all the add/remove/settle log entries before the listed
// indexes.
ourBalance lnwire.MilliSatoshi
theirBalance lnwire.MilliSatoshi
// fee is the amount that will be paid as fees for this commitment
// transaction. The fee is recorded here so that it can be added
// back and recalculated for each new update to the channel state.
fee btcutil.Amount
// feePerKw is the fee per kw used to calculate this commitment
// transaction's fee.
feePerKw btcutil.Amount
// dustLimit is the limit on the commitment transaction such that no output
// values should be below this amount.
dustLimit btcutil.Amount
// outgoingHTLCs is a slice of all the outgoing HTLC's (from our PoV)
// on this commitment transaction.
outgoingHTLCs []PaymentDescriptor
// incomingHTLCs is a slice of all the incoming HTLC's (from our PoV)
// on this commitment transaction.
incomingHTLCs []PaymentDescriptor
// [outgoing|incoming]HTLCIndex is an index that maps an output index
// on the commitment transaction to the payment descriptor that
// represents the HTLC output. Note that these fields are only
// populated if this commitment state belongs to the local node. These
// maps are used when validating any HTLC signatures which are part of
// the local commitment state. We use this map in order to locate the
// details needed to validate an HTLC signature while iterating of the
// outputs int he local commitment view.
outgoignHTLCIndex map[int32]*PaymentDescriptor
incomingHTLCIndex map[int32]*PaymentDescriptor
}
// commitmentKeyRing holds all derived keys needed to construct commitment and
// HTLC transactions. The keys are derived differently depending whether the
// commitment transaction is ours or the remote peer's. Private keys associated
// with each key may belong to the commitment owner or the "other party" which
// is referred to in the field comments, regardless of which is local and which
// is remote.
type commitmentKeyRing struct {
// commitPoint is the "per commitment point" used to derive the tweak for
// each base point.
commitPoint *btcec.PublicKey
// localKeyTweak is the tweak used to derive the local public key from the
// local payment base point or the local private key from the base point
// secret. This may be included in a SignDescriptor to generate signatures
// for the local payment key.
localKeyTweak []byte
// delayKey is the commitment transaction owner's key which is included in
// HTLC success and timeout transaction scripts.
delayKey *btcec.PublicKey
// paymentKey is the other party's payment key in the commitment tx.
paymentKey *btcec.PublicKey
// revocationKey is the key that can be used by the other party to redeem
// outputs from a revoked commitment transaction if it were to be published.
revocationKey *btcec.PublicKey
// localKey is this node's payment key in the commitment tx.
localKey *btcec.PublicKey
// remoteKey is the remote node's payment key in the commitment tx.
remoteKey *btcec.PublicKey
}
// locateOutputIndex is a small helper function to locate the output index of a
// particular HTLC within the current commitment transaction. The duplicate map
// massed in is to be retained for each output within the commitment
// transition. This ensures that we don't assign multiple HTLC's to the same
// index within the commitment transaction.
func locateOutputIndex(p *PaymentDescriptor, tx *wire.MsgTx, ourCommit bool,
dups map[PaymentHash][]int32) (int32, error) {
// Checks to see if element (e) exists in slice (s).
contains := func(s []int32, e int32) bool {
for _, a := range s {
if a == e {
return true
}
}
return false
}
// If this their commitment transaction, we'll be trying to locate
// their pkScripts, otherwise we'll be looking for ours. This is
// required as the commitment states are asymmetric in order to ascribe
// blame in the case of a contract breach.
pkScript := p.theirPkScript
if ourCommit {
pkScript = p.ourPkScript
}
for i, txOut := range tx.TxOut {
if bytes.Equal(txOut.PkScript, pkScript) &&
txOut.Value == int64(p.Amount.ToSatoshis()) {
// If this payment hash and index has already been
// found, then we'll continue in order to avoid any
// duplicate indexes.
if contains(dups[p.RHash], int32(i)) {
continue
}
idx := int32(i)
dups[p.RHash] = append(dups[p.RHash], idx)
return idx, nil
lnwallet: fix bug that retrieves incorrect pkScript in toChannelDelta() Description of bug: When calling ReceiveNewCommitment() we will progress through methods fetchCommitmentView and addHTLC which will add HTLC outputs to the commitment transaction in the local commitment chain and save the pkScript to the relevant PaymentDescriptor which resides in the corresponding updateLog. Finally the local commitment will be added to the local commitment chain. When the same user next calls SignNextCommitment we will again progress through fetchCommitmentView and addHTLC. In addHTLC we will now overwrite the pkScripts in the PaymentDescriptors with the pkScript from the context of the remote commitment. When we later call RevokeCurrentCommitment and proceed into toChannelDelta, we will not be able to find the correct pkScript in the PaymentDescriptor to match it against the outputs in the commitment transaction. This will lead to the nested function locateOutputIndex returning incorrect values. Fixing the bug: We introduce three new fields in PaymentDescriptor: * ourPkScript * theirPkScript * theirPrevPkScript ourPkScript will include the pkScript for the HTLC from the context of the local commitment. theirPkScript will take the value of the latest pkScript for the HTLC from the context of the remote commitment. theirPrevPkScript will take the second-latest pkScript for the HTLC from the context of the remote commitment. This is the value we use in toChannelDelta when we save a revoked commitment from our peer. The appropriate value of these fields are set in the addHTLC method. Additionally we pass a boolean value to toChannelDelta so we know whether we are operating on a local or remote commitment and grab the correct pkScript in locateUpdateIndex.
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}
}
return 0, fmt.Errorf("unable to find htlc: script=%x, value=%v",
pkScript, p.Amount)
}
// populateHtlcIndexes modifies the set of HTLC's locked-into the target view
// to have full indexing information populated. This information is required as
// we need to keep track of the indexes of each HTLC in order to properly write
// the current state to disk, and also to locate the PaymentDescriptor
// corresponding to HTLC outputs in the commitment transaction.
func (c *commitment) populateHtlcIndexes(ourCommitTx bool,
dustLimit btcutil.Amount) error {
// First, we'll set up some state to allow us to locate the output
// index of the all the HTLC's within the commitment transaction. We
// must keep this index so we can validate the HTLC signatures sent to
// us.
dups := make(map[PaymentHash][]int32)
c.outgoignHTLCIndex = make(map[int32]*PaymentDescriptor)
c.incomingHTLCIndex = make(map[int32]*PaymentDescriptor)
// populateIndex is a helper function that populates the necessary
// indexes within the commitment view for a particular HTLC.
populateIndex := func(htlc *PaymentDescriptor, incoming bool) error {
isDust := htlcIsDust(incoming, ourCommitTx, c.feePerKw,
htlc.Amount.ToSatoshis(), dustLimit)
var err error
switch {
// If this is our commitment transaction, and this is a dust
// output then we mark it as such using a -1 index.
case ourCommitTx && isDust:
htlc.localOutputIndex = -1
// If this is the commitment transaction of the remote party,
// and this is a dust output then we mark it as such using a -1
// index.
case !ourCommitTx && isDust:
htlc.remoteOutputIndex = -1
// If this is our commitment transaction, then we'll need to
// locate the output and the index so we can verify an HTLC
// signatures.
case ourCommitTx:
htlc.localOutputIndex, err = locateOutputIndex(htlc, c.txn,
ourCommitTx, dups)
if err != nil {
return err
}
// As this is our commitment transactions, we need to
// keep track of the locations of each output on the
// transaction so we can verify any HTLC signatures
// sent to us after we construct the HTLC view.
if incoming {
c.incomingHTLCIndex[htlc.localOutputIndex] = htlc
} else {
c.outgoignHTLCIndex[htlc.localOutputIndex] = htlc
}
// Otherwise, this is there remote party's commitment
// transaction and we only need to populate the remote output
// index within the HTLC index.
case !ourCommitTx:
htlc.remoteOutputIndex, err = locateOutputIndex(htlc, c.txn,
ourCommitTx, dups)
if err != nil {
return err
}
default:
return fmt.Errorf("invalid commitment configuration")
}
return nil
}
// Finally, we'll need to locate the index within the commitment
// transaction of all the HTLC outputs. This index will be required
// later when we write the commitment state to disk, and also when
// generating signatures for each of the HTLC transactions.
for i := 0; i < len(c.outgoingHTLCs); i++ {
htlc := &c.outgoingHTLCs[i]
if err := populateIndex(htlc, false); err != nil {
return nil
}
}
for i := 0; i < len(c.incomingHTLCs); i++ {
htlc := &c.incomingHTLCs[i]
if err := populateIndex(htlc, true); err != nil {
return nil
}
}
return nil
}
// toChannelDelta converts the target commitment into a format suitable to be
// written to disk after an accepted state transition.
func (c *commitment) toChannelDelta(ourCommit bool) (*channeldb.ChannelDelta, error) {
numHtlcs := len(c.outgoingHTLCs) + len(c.incomingHTLCs)
delta := &channeldb.ChannelDelta{
LocalBalance: c.ourBalance,
RemoteBalance: c.theirBalance,
UpdateNum: c.height,
CommitFee: c.fee,
FeePerKw: c.feePerKw,
Htlcs: make([]*channeldb.HTLC, 0, numHtlcs),
}
for _, htlc := range c.outgoingHTLCs {
outputIndex := htlc.localOutputIndex
if !ourCommit {
outputIndex = htlc.remoteOutputIndex
}
h := &channeldb.HTLC{
Incoming: false,
Amt: htlc.Amount,
RHash: htlc.RHash,
RefundTimeout: htlc.Timeout,
OutputIndex: outputIndex,
}
if ourCommit && htlc.sig != nil {
h.Signature = htlc.sig.Serialize()
}
delta.Htlcs = append(delta.Htlcs, h)
}
for _, htlc := range c.incomingHTLCs {
outputIndex := htlc.localOutputIndex
if !ourCommit {
outputIndex = htlc.remoteOutputIndex
}
h := &channeldb.HTLC{
Incoming: true,
Amt: htlc.Amount,
RHash: htlc.RHash,
RefundTimeout: htlc.Timeout,
OutputIndex: outputIndex,
}
if ourCommit && htlc.sig != nil {
h.Signature = htlc.sig.Serialize()
}
delta.Htlcs = append(delta.Htlcs, h)
}
return delta, nil
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}
// 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
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// commitments we create locally extend the remote node's chain, and vice
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// 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
// startingHeight is the starting height of this commitment chain on a
// session basis.
startingHeight uint64
}
// newCommitmentChain creates a new commitment chain from an initial height.
func newCommitmentChain(initialHeight uint64) *commitmentChain {
return &commitmentChain{
commitments: list.New(),
startingHeight: initialHeight,
}
}
// addCommitment extends the commitment chain by a single commitment. This
// added commitment represents a state update propsed 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)
}
// 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): update with offer vs update distinction
//
// 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. We
// use a distinct index for this purpose, as update's that remove
// entires from the log will be indexed using this counter.
htlcCounter uint64
// ackIndex is a special "pointer" index into the log that tracks the
// position which, up to, all changes have been ACK'd by the remote
// party. When receiving new commitment states, we include all of our
// updates up to this index to restore the commitment view.
ackedIndex uint64
// pendingACKIndex is another special "pointer" index into the log that
// tracks our logIndex value right before we extend the remote party's
// commitment chain. Once we receive an ACK for this changes, then we
// set ackedIndex=pendingAckIndex.
//
// TODO(roasbeef): eventually expand into list when we go back to a
// sliding window format
pendingAckIndex 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 is an index that maps a particular entries index to the
// list element within the list.List above.
updateIndex map[uint64]*list.Element
// offerIndex is an index that maps the counter for offered HTLC's to
// their list elemtn within the main list.List.
htlcIndex map[uint64]*list.Element
}
// newUpdateLog creates a new updateLog instance.
func newUpdateLog() *updateLog {
return &updateLog{
List: list.New(),
updateIndex: make(map[uint64]*list.Element),
htlcIndex: make(map[uint64]*list.Element),
}
}
// 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++
}
// 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 it's 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)
}
// initiateTransition marks that the caller has extended the commitment chain
// of the remote party with the contents of the updateLog. This function will
// mark the log index value at this point so it can later be marked as ACK'd.
func (u *updateLog) initiateTransition() {
u.pendingAckIndex = u.logIndex
}
// ackTransition updates the internal indexes of the updateLog to mark that the
// last pending state transition has been accepted by the remote party. To do
// so, we mark the prior pendingAckIndex as fully ACK'd.
func (u *updateLog) ackTransition() {
u.ackedIndex = u.pendingAckIndex
u.pendingAckIndex = 0
}
// 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 {
nextA = e.Next()
htlc := e.Value.(*PaymentDescriptor)
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 {
logA.removeUpdate(htlc.LogIndex)
logB.removeHtlc(htlc.ParentIndex)
}
}
}
compactLog(ourLog, theirLog)
compactLog(theirLog, ourLog)
}
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// 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
// commitment transactions allowing for a high degree of non-blocking
// bi-directional payment throughput.
//
// In order to allow updates to be fully non-blocking, either side is able to
// create multiple new commitment states up to a pre-determined window size.
// This window size is encoded within InitialRevocationWindow. Before the start
// of a session, both side should send out revocation messages with nil
// preimages in order to populate their revocation window for the remote party.
// Ths method .ExtendRevocationWindow() is used to extend the revocation window
// by a single revocation.
//
// The state machine has for main methods:
// * .SignNextCommitment()
// * Called one one wishes to sign the next commitment, either initiating a
// new state update, or responding to a received commitment.
// * .ReceiveNewCommitment()
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// * Called upon receipt of a new commitment from the remote party. If the
// new commitment is valid, then a revocation should immediately be
// generated and sent.
// * .RevokeCurrentCommitment()
// * Revokes the current commitment. Should be called directly after
// receiving a new commitment.
// * .ReceiveRevocation()
// * Processes a revocation from the remote party. If successful creates a
// new defacto broadcastable state.
//
// See the individual comments within the above methods for further details.
type LightningChannel struct {
// signer is the main signer instances that will be responsible for
// signing any HTLC and commitment transaction generated by the state
// machine.
signer Signer
// signDesc is the primary sign descriptor that is capable of signing
// the commitment transaction that spends the multi-sig output.
signDesc *SignDescriptor
channelEvents chainntnfs.ChainNotifier
// pendingACk denotes if we have an outstanding commitment transaction
// and are waiting for a revocation to be received. Until the
// revocation is received, we're unable to propose a new commitment
// state.
lnwallet: update state machine to the version within the spec This commit updates the internal channel state machine to the one as described within the spec and currently implemented within the rest of the other Lightning implementations. At a high level the following modifications have been made: * When signing we no loner include the index of the remote party’s log that our signature covers. Instead we include ALL of our current updates, but only the updates of the remote party that we’ve ACK’d. * A pending change is considered ACK’d once a revocation message has been received, locking in the changes in the remote party’s commitment transaction. * When sending a new commitment, we remember the index of our log at that point so we can mark that portion of the log as ACK’d once we receive a revocation message from the remote party. * When receiving a new commitment signature, we include ALL of the remote party’s changes that we’ve received but only our set of changes that’ve been ACK’d by the remote party. * Implicitly a revocation message now also implicitly serves to ACK all the changes that were included in the CommitSig message received before it. The resulting change is a rather minor diff. However, with this state machine it’s important to note that the order to sig/revoke messages has been swapped. A proper exchange now looks like the following: * Alice -> Add, Add, Add * Alice -> Sig * Revoke <- Bob * Sig <- Bob * Alice -> Revoke One other thing that’s worth noting is that with this state machine, since what’s included in an update is implicit, both side may need to at times send a new commitment update in the case of a concurrent state transition initiated by both sides. Finally, all counters/indexes have been made 64-bit integers in order to properly match the spec.
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pendingACK bool
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lnwallet: update state machine to the version within the spec This commit updates the internal channel state machine to the one as described within the spec and currently implemented within the rest of the other Lightning implementations. At a high level the following modifications have been made: * When signing we no loner include the index of the remote party’s log that our signature covers. Instead we include ALL of our current updates, but only the updates of the remote party that we’ve ACK’d. * A pending change is considered ACK’d once a revocation message has been received, locking in the changes in the remote party’s commitment transaction. * When sending a new commitment, we remember the index of our log at that point so we can mark that portion of the log as ACK’d once we receive a revocation message from the remote party. * When receiving a new commitment signature, we include ALL of the remote party’s changes that we’ve received but only our set of changes that’ve been ACK’d by the remote party. * Implicitly a revocation message now also implicitly serves to ACK all the changes that were included in the CommitSig message received before it. The resulting change is a rather minor diff. However, with this state machine it’s important to note that the order to sig/revoke messages has been swapped. A proper exchange now looks like the following: * Alice -> Add, Add, Add * Alice -> Sig * Revoke <- Bob * Sig <- Bob * Alice -> Revoke One other thing that’s worth noting is that with this state machine, since what’s included in an update is implicit, both side may need to at times send a new commitment update in the case of a concurrent state transition initiated by both sides. Finally, all counters/indexes have been made 64-bit integers in order to properly match the spec.
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status channelState
// sigPool is a pool of workers that are capable of signing and
// validating signatures in parallel. This is utilized as an
// optimization to void serially signing or validating the HTLC
// signatures, of which there may be hundreds.
sigPool *sigPool
// feeEstimator is used to calculate the fee rate for the channel's
// commitment and cooperative close transactions.
feeEstimator FeeEstimator
lnwallet: update state machine to the version within the spec This commit updates the internal channel state machine to the one as described within the spec and currently implemented within the rest of the other Lightning implementations. At a high level the following modifications have been made: * When signing we no loner include the index of the remote party’s log that our signature covers. Instead we include ALL of our current updates, but only the updates of the remote party that we’ve ACK’d. * A pending change is considered ACK’d once a revocation message has been received, locking in the changes in the remote party’s commitment transaction. * When sending a new commitment, we remember the index of our log at that point so we can mark that portion of the log as ACK’d once we receive a revocation message from the remote party. * When receiving a new commitment signature, we include ALL of the remote party’s changes that we’ve received but only our set of changes that’ve been ACK’d by the remote party. * Implicitly a revocation message now also implicitly serves to ACK all the changes that were included in the CommitSig message received before it. The resulting change is a rather minor diff. However, with this state machine it’s important to note that the order to sig/revoke messages has been swapped. A proper exchange now looks like the following: * Alice -> Add, Add, Add * Alice -> Sig * Revoke <- Bob * Sig <- Bob * Alice -> Revoke One other thing that’s worth noting is that with this state machine, since what’s included in an update is implicit, both side may need to at times send a new commitment update in the case of a concurrent state transition initiated by both sides. Finally, all counters/indexes have been made 64-bit integers in order to properly match the spec.
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// Capcity is the total capacity of this channel.
Capacity btcutil.Amount
// stateHintObsfucator is a 48-bit state hint that's used to obfsucate
// the current state number on the commitment transactions.
stateHintObsfucator [StateHintSize]byte
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// currentHeight is the current height of our local commitment chain.
// This is also the same as the number of updates to the channel we've
// accepted.
currentHeight uint64
// remoteCommitChain is the remote node's commitment chain. Any new
// commitments we initiate are added to the tip of this chain.
remoteCommitChain *commitmentChain
// localCommitChain is our local commitment chain. Any new commitments
// received are added to the tip of this chain. The tail (or lowest
// height) in this chain is our current accepted state, which we are
// able to broadcast safely.
localCommitChain *commitmentChain
channelState *channeldb.OpenChannel
localChanCfg *channeldb.ChannelConfig
remoteChanCfg *channeldb.ChannelConfig
lnwallet: update state machine to the version within the spec This commit updates the internal channel state machine to the one as described within the spec and currently implemented within the rest of the other Lightning implementations. At a high level the following modifications have been made: * When signing we no loner include the index of the remote party’s log that our signature covers. Instead we include ALL of our current updates, but only the updates of the remote party that we’ve ACK’d. * A pending change is considered ACK’d once a revocation message has been received, locking in the changes in the remote party’s commitment transaction. * When sending a new commitment, we remember the index of our log at that point so we can mark that portion of the log as ACK’d once we receive a revocation message from the remote party. * When receiving a new commitment signature, we include ALL of the remote party’s changes that we’ve received but only our set of changes that’ve been ACK’d by the remote party. * Implicitly a revocation message now also implicitly serves to ACK all the changes that were included in the CommitSig message received before it. The resulting change is a rather minor diff. However, with this state machine it’s important to note that the order to sig/revoke messages has been swapped. A proper exchange now looks like the following: * Alice -> Add, Add, Add * Alice -> Sig * Revoke <- Bob * Sig <- Bob * Alice -> Revoke One other thing that’s worth noting is that with this state machine, since what’s included in an update is implicit, both side may need to at times send a new commitment update in the case of a concurrent state transition initiated by both sides. Finally, all counters/indexes have been made 64-bit integers in order to properly match the spec.
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// [local|remote]Log is a (mostly) append-only log storing all the HTLC
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// updates to this channel. The log is walked backwards as HTLC updates
// are applied in order to re-construct a commitment transaction from a
// commitment. The log is compacted once a revocation is received.
lnwallet: update state machine to the version within the spec This commit updates the internal channel state machine to the one as described within the spec and currently implemented within the rest of the other Lightning implementations. At a high level the following modifications have been made: * When signing we no loner include the index of the remote party’s log that our signature covers. Instead we include ALL of our current updates, but only the updates of the remote party that we’ve ACK’d. * A pending change is considered ACK’d once a revocation message has been received, locking in the changes in the remote party’s commitment transaction. * When sending a new commitment, we remember the index of our log at that point so we can mark that portion of the log as ACK’d once we receive a revocation message from the remote party. * When receiving a new commitment signature, we include ALL of the remote party’s changes that we’ve received but only our set of changes that’ve been ACK’d by the remote party. * Implicitly a revocation message now also implicitly serves to ACK all the changes that were included in the CommitSig message received before it. The resulting change is a rather minor diff. However, with this state machine it’s important to note that the order to sig/revoke messages has been swapped. A proper exchange now looks like the following: * Alice -> Add, Add, Add * Alice -> Sig * Revoke <- Bob * Sig <- Bob * Alice -> Revoke One other thing that’s worth noting is that with this state machine, since what’s included in an update is implicit, both side may need to at times send a new commitment update in the case of a concurrent state transition initiated by both sides. Finally, all counters/indexes have been made 64-bit integers in order to properly match the spec.
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localUpdateLog *updateLog
remoteUpdateLog *updateLog
// pendingFeeUpdate is set to the fee-per-kw we last sent (if we are
// channel initiator) or received (if non-initiator) in an update fee
// message, which haven't yet been included in a commitment. It will
// be nil if no fee update is un-committed.
pendingFeeUpdate *btcutil.Amount
// pendingAckFeeUpdate is set to the last committed fee update which is
// not yet ACKed. This value will be nil if a fee update hasn't been
// initiated.
pendingAckFeeUpdate *btcutil.Amount
// rHashMap is a map with PaymentHashes pointing to their respective
// PaymentDescriptors. We insert *PaymentDescriptors whenever we
// receive HTLCs. When a state transition happens (settling or
// canceling the HTLC), rHashMap will provide an efficient
// way to lookup the original PaymentDescriptor.
rHashMap map[PaymentHash][]*PaymentDescriptor
lnwallet: update state machine to the version within the spec This commit updates the internal channel state machine to the one as described within the spec and currently implemented within the rest of the other Lightning implementations. At a high level the following modifications have been made: * When signing we no loner include the index of the remote party’s log that our signature covers. Instead we include ALL of our current updates, but only the updates of the remote party that we’ve ACK’d. * A pending change is considered ACK’d once a revocation message has been received, locking in the changes in the remote party’s commitment transaction. * When sending a new commitment, we remember the index of our log at that point so we can mark that portion of the log as ACK’d once we receive a revocation message from the remote party. * When receiving a new commitment signature, we include ALL of the remote party’s changes that we’ve received but only our set of changes that’ve been ACK’d by the remote party. * Implicitly a revocation message now also implicitly serves to ACK all the changes that were included in the CommitSig message received before it. The resulting change is a rather minor diff. However, with this state machine it’s important to note that the order to sig/revoke messages has been swapped. A proper exchange now looks like the following: * Alice -> Add, Add, Add * Alice -> Sig * Revoke <- Bob * Sig <- Bob * Alice -> Revoke One other thing that’s worth noting is that with this state machine, since what’s included in an update is implicit, both side may need to at times send a new commitment update in the case of a concurrent state transition initiated by both sides. Finally, all counters/indexes have been made 64-bit integers in order to properly match the spec.
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// FundingWitnessScript is the witness script for the 2-of-2 multi-sig
// that opened the channel.
FundingWitnessScript []byte
lnwallet: update state machine to the version within the spec This commit updates the internal channel state machine to the one as described within the spec and currently implemented within the rest of the other Lightning implementations. At a high level the following modifications have been made: * When signing we no loner include the index of the remote party’s log that our signature covers. Instead we include ALL of our current updates, but only the updates of the remote party that we’ve ACK’d. * A pending change is considered ACK’d once a revocation message has been received, locking in the changes in the remote party’s commitment transaction. * When sending a new commitment, we remember the index of our log at that point so we can mark that portion of the log as ACK’d once we receive a revocation message from the remote party. * When receiving a new commitment signature, we include ALL of the remote party’s changes that we’ve received but only our set of changes that’ve been ACK’d by the remote party. * Implicitly a revocation message now also implicitly serves to ACK all the changes that were included in the CommitSig message received before it. The resulting change is a rather minor diff. However, with this state machine it’s important to note that the order to sig/revoke messages has been swapped. A proper exchange now looks like the following: * Alice -> Add, Add, Add * Alice -> Sig * Revoke <- Bob * Sig <- Bob * Alice -> Revoke One other thing that’s worth noting is that with this state machine, since what’s included in an update is implicit, both side may need to at times send a new commitment update in the case of a concurrent state transition initiated by both sides. Finally, all counters/indexes have been made 64-bit integers in order to properly match the spec.
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fundingTxIn *wire.TxIn
fundingP2WSH []byte
// ForceCloseSignal is a channel that is closed to indicate that a
// local system has initiated a force close by broadcasting the current
// commitment transaction directly on-chain.
ForceCloseSignal chan struct{}
// UnilateralCloseSignal is a channel that is closed to indicate that
// the remote party has performed a unilateral close by broadcasting
// their version of the commitment transaction on-chain.
UnilateralCloseSignal chan struct{}
// UnilateralClose is a channel that will be sent upon by the close
// observer once the unilateral close of a channel is detected.
UnilateralClose chan *UnilateralCloseSummary
// ContractBreach is a channel that is used to communicate the data
// necessary to fully resolve the channel in the case that a contract
// breach is detected. A contract breach occurs it is detected that the
// counterparty has broadcast a prior *revoked* state.
ContractBreach chan *BreachRetribution
// LocalFundingKey is the public key under control by the wallet that
// was used for the 2-of-2 funding output which created this channel.
LocalFundingKey *btcec.PublicKey
// RemoteFundingKey is the public key for the remote channel counter
// party which used for the 2-of-2 funding output which created this
// channel.
RemoteFundingKey *btcec.PublicKey
// availableLocalBalance represent the amount of available money which
// might be processed by this channel at the specific point of time.
availableLocalBalance lnwire.MilliSatoshi
sync.RWMutex
wg sync.WaitGroup
shutdown int32
quit chan struct{}
}
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// NewLightningChannel creates a new, active payment channel given an
// implementation of the chain notifier, channel database, and the current
// settled channel state. Throughout state transitions, then channel will
// automatically persist pertinent state to the database in an efficient
// manner.
func NewLightningChannel(signer Signer, events chainntnfs.ChainNotifier,
fe FeeEstimator, state *channeldb.OpenChannel) (*LightningChannel, error) {
localKey := state.LocalChanCfg.MultiSigKey.SerializeCompressed()
remoteKey := state.RemoteChanCfg.MultiSigKey.SerializeCompressed()
multiSigScript, err := genMultiSigScript(localKey, remoteKey)
if err != nil {
return nil, err
}
var stateHint [StateHintSize]byte
if state.IsInitiator {
stateHint = deriveStateHintObfuscator(
state.LocalChanCfg.PaymentBasePoint,
state.RemoteChanCfg.PaymentBasePoint,
)
} else {
stateHint = deriveStateHintObfuscator(
state.RemoteChanCfg.PaymentBasePoint,
state.LocalChanCfg.PaymentBasePoint,
)
}
lc := &LightningChannel{
// TODO(roasbeef): tune num sig workers?
sigPool: newSigPool(runtime.NumCPU(), signer),
signer: signer,
channelEvents: events,
feeEstimator: fe,
stateHintObsfucator: stateHint,
currentHeight: state.NumUpdates,
remoteCommitChain: newCommitmentChain(state.NumUpdates),
localCommitChain: newCommitmentChain(state.NumUpdates),
channelState: state,
localChanCfg: &state.LocalChanCfg,
remoteChanCfg: &state.RemoteChanCfg,
lnwallet: update state machine to the version within the spec This commit updates the internal channel state machine to the one as described within the spec and currently implemented within the rest of the other Lightning implementations. At a high level the following modifications have been made: * When signing we no loner include the index of the remote party’s log that our signature covers. Instead we include ALL of our current updates, but only the updates of the remote party that we’ve ACK’d. * A pending change is considered ACK’d once a revocation message has been received, locking in the changes in the remote party’s commitment transaction. * When sending a new commitment, we remember the index of our log at that point so we can mark that portion of the log as ACK’d once we receive a revocation message from the remote party. * When receiving a new commitment signature, we include ALL of the remote party’s changes that we’ve received but only our set of changes that’ve been ACK’d by the remote party. * Implicitly a revocation message now also implicitly serves to ACK all the changes that were included in the CommitSig message received before it. The resulting change is a rather minor diff. However, with this state machine it’s important to note that the order to sig/revoke messages has been swapped. A proper exchange now looks like the following: * Alice -> Add, Add, Add * Alice -> Sig * Revoke <- Bob * Sig <- Bob * Alice -> Revoke One other thing that’s worth noting is that with this state machine, since what’s included in an update is implicit, both side may need to at times send a new commitment update in the case of a concurrent state transition initiated by both sides. Finally, all counters/indexes have been made 64-bit integers in order to properly match the spec.
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localUpdateLog: newUpdateLog(),
remoteUpdateLog: newUpdateLog(),
rHashMap: make(map[PaymentHash][]*PaymentDescriptor),
Capacity: state.Capacity,
FundingWitnessScript: multiSigScript,
ForceCloseSignal: make(chan struct{}),
UnilateralClose: make(chan *UnilateralCloseSummary, 1),
UnilateralCloseSignal: make(chan struct{}),
ContractBreach: make(chan *BreachRetribution, 1),
LocalFundingKey: state.LocalChanCfg.MultiSigKey,
RemoteFundingKey: state.RemoteChanCfg.MultiSigKey,
quit: make(chan struct{}),
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}
// Initialize both of our chains using current un-revoked commitment
// for each side.
lc.localCommitChain.addCommitment(&commitment{
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height: lc.currentHeight,
ourBalance: state.LocalBalance,
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ourMessageIndex: 0,
theirBalance: state.RemoteBalance,
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theirMessageIndex: 0,
fee: state.CommitFee,
feePerKw: state.FeePerKw,
})
walletLog.Debugf("ChannelPoint(%v), starting local commitment: %v",
state.FundingOutpoint, newLogClosure(func() string {
return spew.Sdump(lc.localCommitChain.tail())
}),
)
// To obtain the proper height for the remote node's commitment state,
// we'll need to fetch the tail end of their revocation log from the
// database.
logTail, err := state.RevocationLogTail()
if err != nil && err != channeldb.ErrNoActiveChannels &&
err != channeldb.ErrNoPastDeltas {
return nil, err
}
remoteCommitment := &commitment{
ourBalance: state.LocalBalance,
ourMessageIndex: 0,
theirBalance: state.RemoteBalance,
theirMessageIndex: 0,
fee: state.CommitFee,
feePerKw: state.FeePerKw,
}
if logTail == nil {
remoteCommitment.height = 0
} else {
remoteCommitment.height = logTail.UpdateNum + 1
}
lc.remoteCommitChain.addCommitment(remoteCommitment)
walletLog.Debugf("ChannelPoint(%v), starting remote commitment: %v",
state.FundingOutpoint, newLogClosure(func() string {
return spew.Sdump(lc.remoteCommitChain.tail())
}),
)
// If we're restarting from a channel with history, then restore the
// update in-memory update logs to that of the prior state.
if lc.currentHeight != 0 {
lc.restoreStateLogs()
}
// Create the sign descriptor which we'll be using very frequently to
// request a signature for the 2-of-2 multi-sig from the signer in
// order to complete channel state transitions.
fundingPkScript, err := witnessScriptHash(multiSigScript)
if err != nil {
return nil, err
}
lc.fundingTxIn = wire.NewTxIn(&state.FundingOutpoint, nil, nil)
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lc.fundingP2WSH = fundingPkScript
lc.signDesc = &SignDescriptor{
PubKey: lc.localChanCfg.MultiSigKey,
WitnessScript: multiSigScript,
Output: &wire.TxOut{
PkScript: lc.fundingP2WSH,
Value: int64(lc.channelState.Capacity),
},
HashType: txscript.SigHashAll,
InputIndex: 0,
}
// We'll only launch a close observer if the ChainNotifier
// implementation is non-nil. Passing a nil value indicates that the
// channel shouldn't be actively watched for.
if lc.channelEvents != nil {
// Register for a notification to be dispatched if the funding
// outpoint has been spent. This indicates that either us or
// the remote party has broadcasted a commitment transaction
// on-chain.
fundingOut := &lc.fundingTxIn.PreviousOutPoint
// As a height hint, we'll try to use the opening height, but
// if the channel isn't yet open, then we'll use the height it
// was broadcast at.
heightHint := lc.channelState.ShortChanID.BlockHeight
if heightHint == 0 {
heightHint = lc.channelState.FundingBroadcastHeight
}
channelCloseNtfn, err := lc.channelEvents.RegisterSpendNtfn(
fundingOut, heightHint,
)
if err != nil {
return nil, err
}
// Launch the close observer which will vigilantly watch the
// network for any broadcasts the current or prior commitment
// transactions, taking action accordingly.
lc.wg.Add(1)
go lc.closeObserver(channelCloseNtfn)
}
// Initialize the available local balance
s := lc.StateSnapshot()
lc.availableLocalBalance = s.LocalBalance
// Finally, we'll kick of the signature job pool to handle any upcoming
// commitment state generation and validation.
if lc.sigPool.Start(); err != nil {
return nil, err
}
return lc, nil
}
// Stop gracefully shuts down any active goroutines spawned by the
// LightningChannel during regular duties.
func (lc *LightningChannel) Stop() {
if !atomic.CompareAndSwapInt32(&lc.shutdown, 0, 1) {
return
}
// TODO(roasbeef): ensure that when channel links and breach arbs exit,
// that they call Stop?
lc.sigPool.Stop()
close(lc.quit)
lc.wg.Wait()
}
// HtlcRetribution contains all the items necessary to seep a revoked HTLC
// transaction from a revoked commitment transaction broadcast by the remot
// party.
type HtlcRetribution struct {
// SignDesc is a design descriptor capable of generating the necessary
// signatures to satisfy the revocation clause of the HTLC's public key
// script.
SignDesc SignDescriptor
// OutPoint is the target outpoint of this HTLC pointing to the
// breached commitment transaction.
OutPoint wire.OutPoint
// IsIncoming is a boolean flag that indicates whether or not this
// HTLC was accepted from the counterparty. A false value indicates that
// this HTLC was offered by us. This flag is used determine the exact
// witness type should be used to sweep the output.
IsIncoming bool
}
// BreachRetribution contains all the data necessary to bring a channel
// counterparty to justice claiming ALL lingering funds within the channel in
// the scenario that they broadcast a revoked commitment transaction. A
// BreachRetribution is created by the closeObserver if it detects an
// uncooperative close of the channel which uses a revoked commitment
// transaction. The BreachRetribution is then sent over the ContractBreach
// channel in order to allow the subscriber of the channel to dispatch justice.
type BreachRetribution struct {
// BreachTransaction is the transaction which breached the channel
// contract by spending from the funding multi-sig with a revoked
// commitment transaction.
BreachTransaction *wire.MsgTx
// RevokedStateNum is the revoked state number which was broadcast.
RevokedStateNum uint64
// PendingHTLCs is a slice of the HTLCs which were pending at this
// point within the channel's history transcript.
PendingHTLCs []*channeldb.HTLC
// LocalOutputSignDesc is a SignDescriptor which is capable of
// generating the signature necessary to sweep the output within the
// BreachTransaction that pays directly us.
// NOTE: A nil value indicates that the local output is considered dust
// according to the remote party's dust limit.
LocalOutputSignDesc *SignDescriptor
// LocalOutpoint is the outpoint of the output paying to us (the local
// party) within the breach transaction.
LocalOutpoint wire.OutPoint
// RemoteOutputSignDesc is a SignDescriptor which is capable of
// generating the signature required to claim the funds as described
// within the revocation clause of the remote party's commitment
// output.
// NOTE: A nil value indicates that the local output is considered dust
// according to the remote party's dust limit.
RemoteOutputSignDesc *SignDescriptor
// RemoteOutpoint is the output of the output paying to the remote
// party within the breach transaction.
RemoteOutpoint wire.OutPoint
// HtlcRetributions is a slice of HTLC retributions for each output
// active HTLC output within the breached commitment transaction.
HtlcRetributions []HtlcRetribution
}
// newBreachRetribution creates a new fully populated BreachRetribution for the
// passed channel, at a particular revoked state number, and one which targets
// the passed commitment transaction.
func newBreachRetribution(chanState *channeldb.OpenChannel, stateNum uint64,
broadcastCommitment *wire.MsgTx) (*BreachRetribution, error) {
commitHash := broadcastCommitment.TxHash()
// Query the on-disk revocation log for the snapshot which was recorded
// at this particular state num.
revokedSnapshot, err := chanState.FindPreviousState(stateNum)
if err != nil {
return nil, err
}
// With the state number broadcast known, we can now derive/restore the
// proper revocation preimage necessary to sweep the remote party's
// output.
revocationPreimage, err := chanState.RevocationStore.LookUp(stateNum)
if err != nil {
return nil, err
}
commitmentSecret, commitmentPoint := btcec.PrivKeyFromBytes(btcec.S256(),
revocationPreimage[:])
// With the commitment point generated, we can now generate the four
// keys we'll need to reconstruct the commitment state,
keyRing := deriveCommitmentKeys(commitmentPoint, false,
&chanState.LocalChanCfg, &chanState.RemoteChanCfg)
// Next, reconstruct the scripts as they were present at this state
// number so we can have the proper witness script to sign and include
// within the final witness.
remoteDelay := uint32(chanState.RemoteChanCfg.CsvDelay)
remotePkScript, err := commitScriptToSelf(remoteDelay, keyRing.delayKey,
keyRing.revocationKey)
if err != nil {
return nil, err
}
remoteWitnessHash, err := witnessScriptHash(remotePkScript)
if err != nil {
return nil, err
}
localPkScript, err := commitScriptUnencumbered(keyRing.localKey)
if err != nil {
return nil, err
}
// In order to fully populate the breach retribution struct, we'll need
// to find the exact index of the local+remote commitment outputs.
localOutpoint := wire.OutPoint{
Hash: commitHash,
}
remoteOutpoint := wire.OutPoint{
Hash: commitHash,
}
for i, txOut := range broadcastCommitment.TxOut {
switch {
case bytes.Equal(txOut.PkScript, localPkScript):
localOutpoint.Index = uint32(i)
case bytes.Equal(txOut.PkScript, remoteWitnessHash):
remoteOutpoint.Index = uint32(i)
}
}
// Conditionally instantiate a sign descriptor for each of the
// commitment outputs. If either is considered dust using the remote
// party's dust limit, the respective sign descriptor will be nil.
var (
localSignDesc *SignDescriptor
remoteSignDesc *SignDescriptor
)
// Compute the local and remote balances in satoshis.
localAmt := revokedSnapshot.LocalBalance.ToSatoshis()
remoteAmt := revokedSnapshot.RemoteBalance.ToSatoshis()
// If the local balance exceeds the remote party's dust limit,
// instantiate the local sign descriptor.
if localAmt >= chanState.RemoteChanCfg.DustLimit {
localSignDesc = &SignDescriptor{
SingleTweak: keyRing.localKeyTweak,
PubKey: chanState.LocalChanCfg.PaymentBasePoint,
WitnessScript: localPkScript,
Output: &wire.TxOut{
PkScript: localPkScript,
Value: int64(localAmt),
},
HashType: txscript.SigHashAll,
}
}
// Similarly, if the remote balance exceeds the remote party's dust
// limit, assemble the remote sign descriptor.
if remoteAmt >= chanState.RemoteChanCfg.DustLimit {
remoteSignDesc = &SignDescriptor{
PubKey: chanState.LocalChanCfg.RevocationBasePoint,
DoubleTweak: commitmentSecret,
WitnessScript: remotePkScript,
Output: &wire.TxOut{
PkScript: remoteWitnessHash,
Value: int64(remoteAmt),
},
HashType: txscript.SigHashAll,
}
}
// With the commitment outputs located, we'll now generate all the
// retribution structs for each of the HTLC transactions active on the
// remote commitment transaction.
htlcRetributions := make([]HtlcRetribution, len(revokedSnapshot.Htlcs))
for i, htlc := range revokedSnapshot.Htlcs {
var (
htlcScript []byte
err error
)
// If this is an incoming HTLC, then this means that they were
// the sender of the HTLC (relative to us). So we'll
// re-generate the sender HTLC script.
if htlc.Incoming {
htlcScript, err = senderHTLCScript(keyRing.localKey,
keyRing.remoteKey, keyRing.revocationKey, htlc.RHash[:])
if err != nil {
return nil, err
}
// Otherwise, is this was an outgoing HTLC that we sent, then
// from the PoV of the remote commitment state, they're the
// receiver of this HTLC.
} else {
htlcScript, err = receiverHTLCScript(
htlc.RefundTimeout, keyRing.localKey, keyRing.remoteKey,
keyRing.revocationKey, htlc.RHash[:],
)
if err != nil {
return nil, err
}
}
htlcRetributions[i] = HtlcRetribution{
SignDesc: SignDescriptor{
PubKey: chanState.LocalChanCfg.RevocationBasePoint,
DoubleTweak: commitmentSecret,
WitnessScript: htlcScript,
Output: &wire.TxOut{
Value: int64(htlc.Amt.ToSatoshis()),
},
HashType: txscript.SigHashAll,
},
OutPoint: wire.OutPoint{
Hash: commitHash,
Index: uint32(htlc.OutputIndex),
},
IsIncoming: htlc.Incoming,
}
}
// Finally, with all the necessary data constructed, we can create the
// BreachRetribution struct which houses all the data necessary to
// swiftly bring justice to the cheating remote party.
return &BreachRetribution{
BreachTransaction: broadcastCommitment,
RevokedStateNum: stateNum,
PendingHTLCs: revokedSnapshot.Htlcs,
LocalOutpoint: localOutpoint,
LocalOutputSignDesc: localSignDesc,
RemoteOutpoint: remoteOutpoint,
RemoteOutputSignDesc: remoteSignDesc,
HtlcRetributions: htlcRetributions,
}, nil
}
// closeObserver is a goroutine which watches the network for any spends of the
// multi-sig funding output. A spend from the multi-sig output may occur under
// the following three scenarios: a cooperative close, a unilateral close, and
// a uncooperative contract breaching close. In the case of the last scenario a
// BreachRetribution struct is created and sent over the ContractBreach channel
// notifying subscribers that the counterparty has violated the condition of
// the channel by broadcasting a revoked prior state.
//
// NOTE: This MUST be run as a goroutine.
func (lc *LightningChannel) closeObserver(channelCloseNtfn *chainntnfs.SpendEvent) {
defer lc.wg.Done()
walletLog.Infof("Close observer for ChannelPoint(%v) active",
lc.channelState.FundingOutpoint)
var (
commitSpend *chainntnfs.SpendDetail
ok bool
)
select {
// If the daemon is shutting down, then this notification channel will
// be closed, so check the second read-value to avoid a false positive.
case commitSpend, ok = <-channelCloseNtfn.Spend:
if !ok {
return
}
// Otherwise, we've beeen signalled to bail out early by the
// caller/maintainer of this channel.
case <-lc.quit:
// As we're exiting before the spend notification has been
// triggered, we'll cancel the notification intent so the
// ChainNotiifer can free up the resources.
channelCloseNtfn.Cancel()
return
}
// If we've already initiated a local cooperative or unilateral close
// locally, then we have nothing more to do.
lc.RLock()
if lc.status == channelClosed || lc.status == channelDispute ||
lc.status == channelClosing {
lc.RUnlock()
return
}
lc.RUnlock()
// Otherwise, the remote party might have broadcast a prior revoked
// state...!!!
commitTxBroadcast := commitSpend.SpendingTx
// If this is our commitment transaction, then we can exit here as we
// don't have any further processing we need to do (we can't cheat
// ourselves :p).
commitmentHash := lc.channelState.CommitTx.TxHash()
isOurCommitment := commitSpend.SpenderTxHash.IsEqual(&commitmentHash)
if isOurCommitment {
return
}
lc.Lock()
defer lc.Unlock()
walletLog.Warnf("Unprompted commitment broadcast for ChannelPoint(%v) "+
"detected!", lc.channelState.FundingOutpoint)
// Decode the state hint encoded within the commitment transaction to
// determine if this is a revoked state or not.
obsfucator := lc.stateHintObsfucator
broadcastStateNum := GetStateNumHint(commitTxBroadcast, obsfucator)
currentStateNum := lc.currentHeight
// TODO(roasbeef): track heights distinctly?
switch {
// If state number spending transaction matches the current latest
// state, then they've initiated a unilateral close. So we'll trigger
// the unilateral close signal so subscribers can clean up the state as
// necessary.
//
// We'll also handle the case of the remote party broadcasting their
// commitment transaction which is one height above ours. This case can
// arise when we initiate a state transition, but the remote party has
// a fail crash _after_ accepting the new state, but _before_ sending
// their signature to us.
case broadcastStateNum >= currentStateNum:
walletLog.Infof("Unilateral close of ChannelPoint(%v) "+
"detected", lc.channelState.FundingOutpoint)
// As we've detected that the channel has been closed,
// immediately delete the state from disk, creating a close
// summary for future usage by related sub-systems.
//
// TODO(roasbeef): include HTLC's
// * and time-locked balance, NEED TO???
closeSummary := channeldb.ChannelCloseSummary{
ChanPoint: lc.channelState.FundingOutpoint,
ClosingTXID: *commitSpend.SpenderTxHash,
RemotePub: lc.channelState.IdentityPub,
Capacity: lc.Capacity,
SettledBalance: lc.channelState.LocalBalance.ToSatoshis(),
CloseType: channeldb.ForceClose,
IsPending: true,
}
if err := lc.DeleteState(&closeSummary); err != nil {
walletLog.Errorf("unable to delete channel state: %v",
err)
}
// First, we'll generate the commitment point and the
// revocation point so we can re-construct the HTLC state and
// also our payment key.
commitPoint := lc.channelState.RemoteCurrentRevocation
keyRing := deriveCommitmentKeys(commitPoint, false,
lc.localChanCfg, lc.remoteChanCfg)
// Next, we'll obtain HTLC resolutions for all the outgoing
// HTLC's we had on their commitment transaction.
htlcResolutions, err := extractHtlcResolutions(
lc.channelState.FeePerKw, false, lc.signer,
lc.channelState.Htlcs, keyRing,
lc.localChanCfg, lc.remoteChanCfg,
*commitSpend.SpenderTxHash)
if err != nil {
walletLog.Errorf("unable to create htlc "+
"resolutions: %v", err)
return
}
// Before we can generate the proper sign descriptor, we'll
// need to locate the output index of our non-delayed output on
// the commitment transaction.
selfP2WKH, err := commitScriptUnencumbered(keyRing.localKey)
if err != nil {
walletLog.Errorf("unable to create self commit "+
"script: %v", err)
return
}
var selfPoint *wire.OutPoint
for outputIndex, txOut := range commitTxBroadcast.TxOut {
if bytes.Equal(txOut.PkScript, selfP2WKH) {
selfPoint = &wire.OutPoint{
Hash: *commitSpend.SpenderTxHash,
Index: uint32(outputIndex),
}
break
}
}
// With the HTLC's taken care of, we'll generate the sign
// descriptor necessary to sweep our commitment output, but
// only if we had a non-trimmed balance.
var selfSignDesc *SignDescriptor
if selfPoint != nil {
localPayBase := lc.localChanCfg.PaymentBasePoint
selfSignDesc = &SignDescriptor{
PubKey: localPayBase,
SingleTweak: keyRing.localKeyTweak,
WitnessScript: selfP2WKH,
Output: &wire.TxOut{
Value: int64(lc.channelState.LocalBalance.ToSatoshis()),
PkScript: selfP2WKH,
},
HashType: txscript.SigHashAll,
}
}
// TODO(roasbeef): send msg before writing to disk
// * need to ensure proper fault tolerance in all cases
// * get ACK from the consumer of the ntfn before writing to disk?
// * no harm in repeated ntfns: at least once semantics
// Notify any subscribers that we've detected a unilateral
// commitment transaction broadcast.
close(lc.UnilateralCloseSignal)
// We'll also send all the details necessary to re-claim funds
// that are suspended within any contracts.
lc.UnilateralClose <- &UnilateralCloseSummary{
SpendDetail: commitSpend,
ChannelCloseSummary: closeSummary,
SelfOutPoint: selfPoint,
SelfOutputSignDesc: selfSignDesc,
MaturityDelay: uint32(lc.remoteChanCfg.CsvDelay),
HtlcResolutions: htlcResolutions,
}
// If the state number broadcast is lower than the remote node's
// current un-revoked height, then THEY'RE ATTEMPTING TO VIOLATE THE
// CONTRACT LAID OUT WITHIN THE PAYMENT CHANNEL. Therefore we close
// the signal indicating a revoked broadcast to allow subscribers to
// swiftly dispatch justice!!!
case broadcastStateNum < currentStateNum:
walletLog.Warnf("Remote peer has breached the channel "+
"contract for ChannelPoint(%v). Revoked state #%v was "+
"broadcast!!!", lc.channelState.FundingOutpoint,
broadcastStateNum)
// Create a new reach retribution struct which contains all the
// data needed to swiftly bring the cheating peer to justice.
retribution, err := newBreachRetribution(lc.channelState,
broadcastStateNum, commitTxBroadcast)
if err != nil {
walletLog.Errorf("unable to create breach retribution: %v", err)
return
}
walletLog.Debugf("Punishment breach retribution created: %v",
spew.Sdump(retribution))
// Finally, send the retribution struct over the contract beach
// channel to allow the observer the use the breach retribution
// to sweep ALL funds.
lc.ContractBreach <- retribution
}
}
// htlcTimeoutFee returns the fee in satoshis required for an HTLC timeout
// transaction based on the current fee rate.
func htlcTimeoutFee(feePerKw btcutil.Amount) btcutil.Amount {
return (feePerKw * HtlcTimeoutWeight) / 1000
}
// htlcSuccessFee returns the fee in satoshis required for an HTLC success
// transaction based on the current fee rate.
func htlcSuccessFee(feePerKw btcutil.Amount) btcutil.Amount {
return (feePerKw * HtlcSuccessWeight) / 1000
}
// htlcIsDust determines if an HTLC output is dust or not depending on two
// bits: if the HTLC is incoming and if the HTLC will be placed on our
// commitment transaction, or theirs. These two pieces of information are
// require as we currently used second-level HTLC transactions ass off-chain
// covenants. Depending on the two bits, we'll either be using a timeout or
// success transaction which have different weights.
func htlcIsDust(incoming, ourCommit bool,
feePerKw, htlcAmt, dustLimit btcutil.Amount) bool {
// First we'll determine the fee required for this HTLC based on if this is
// an incoming HTLC or not, and also on whose commitment transaction it
// will be placed on.
var htlcFee btcutil.Amount
switch {
// If this is an incoming HTLC on our commitment transaction, then the
// second-level transaction will be a success transaction.
case incoming && ourCommit:
htlcFee = htlcSuccessFee(feePerKw)
// If this is an incoming HTLC on their commitment transaction, then
// we'll be using a second-level timeout transaction as they've added
// this HTLC.
case incoming && !ourCommit:
htlcFee = htlcTimeoutFee(feePerKw)
// If this is an outgoing HTLC on our commitment transaction, then
// we'll be using a timeout transaction as we're the sender of the
// HTLC.
case !incoming && ourCommit:
htlcFee = htlcTimeoutFee(feePerKw)
// If this is an outgoing HTLC on their commitment transaction, then
// we'll be using an HTLC success transaction as they're the receiver
// of this HTLC.
case !incoming && !ourCommit:
htlcFee = htlcTimeoutFee(feePerKw)
}
return (htlcAmt - htlcFee) < dustLimit
}
// restoreStateLogs runs through the current locked-in HTLCs from the point of
// view of the channel and insert corresponding log entries (both local and
// remote) for each HTLC read from disk. This method is required to sync the
// in-memory state of the state machine with that read from persistent storage.
func (lc *LightningChannel) restoreStateLogs() error {
var pastHeight uint64
if lc.currentHeight > 0 {
pastHeight = lc.currentHeight - 1
}
// Obtain the local and remote channel configurations. These house all
// the relevant public keys and points we'll need in order to restore
// the state log.
localChanCfg := lc.localChanCfg
remoteChanCfg := lc.remoteChanCfg
// In order to reconstruct the pkScripts on each of the pending HTLC
// outputs (if any) we'll need to regenerate the current revocation for
// this current un-revoked state.
ourRevPreImage, err := lc.channelState.RevocationProducer.AtIndex(lc.currentHeight)
if err != nil {
return err
}
// With the commitment secret recovered, we'll generate the revocation
// used on the *local* commitment transaction. This is computed using
// the point derived from the commitment secret at the remote party's
// revocation based.
localCommitPoint := ComputeCommitmentPoint(ourRevPreImage[:])
localCommitKeys := deriveCommitmentKeys(localCommitPoint, true,
localChanCfg, remoteChanCfg)
remoteCommitPoint := lc.channelState.RemoteCurrentRevocation
remoteCommitKeys := deriveCommitmentKeys(remoteCommitPoint, false,
localChanCfg, remoteChanCfg)
lnwallet: update state machine to the version within the spec This commit updates the internal channel state machine to the one as described within the spec and currently implemented within the rest of the other Lightning implementations. At a high level the following modifications have been made: * When signing we no loner include the index of the remote party’s log that our signature covers. Instead we include ALL of our current updates, but only the updates of the remote party that we’ve ACK’d. * A pending change is considered ACK’d once a revocation message has been received, locking in the changes in the remote party’s commitment transaction. * When sending a new commitment, we remember the index of our log at that point so we can mark that portion of the log as ACK’d once we receive a revocation message from the remote party. * When receiving a new commitment signature, we include ALL of the remote party’s changes that we’ve received but only our set of changes that’ve been ACK’d by the remote party. * Implicitly a revocation message now also implicitly serves to ACK all the changes that were included in the CommitSig message received before it. The resulting change is a rather minor diff. However, with this state machine it’s important to note that the order to sig/revoke messages has been swapped. A proper exchange now looks like the following: * Alice -> Add, Add, Add * Alice -> Sig * Revoke <- Bob * Sig <- Bob * Alice -> Revoke One other thing that’s worth noting is that with this state machine, since what’s included in an update is implicit, both side may need to at times send a new commitment update in the case of a concurrent state transition initiated by both sides. Finally, all counters/indexes have been made 64-bit integers in order to properly match the spec.
2017-02-21 04:55:33 +03:00
var ourCounter, theirCounter uint64
// Grab the current fee rate as we'll need this to determine if the
// prior HTLC's were considered dust or not at this particular
// commitment sate.
feeRate := lc.channelState.FeePerKw
// TODO(roasbeef): partition entries added based on our current review
// an our view of them from the log?
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
// inadvertently trigger replays
// The proper pkScripts for this PaymentDescriptor must be
// generated so we can easily locate them within the commitment
// transaction in the future.
var ourP2WSH, theirP2WSH, ourWitnessScript, theirWitnessScript []byte
// If the either outputs is dust from the local or remote
// node's perspective, then we don't need to generate the
// scripts as we only generate them in order to locate the
// outputs within the commitment transaction. As we'll mark
// dust with a special output index in the on-disk state
// snapshot.
isDustLocal := htlcIsDust(htlc.Incoming, true, feeRate,
htlc.Amt.ToSatoshis(), localChanCfg.DustLimit)
isDustRemote := htlcIsDust(htlc.Incoming, false, feeRate,
htlc.Amt.ToSatoshis(), remoteChanCfg.DustLimit)
if !isDustLocal {
ourP2WSH, ourWitnessScript, err = lc.genHtlcScript(
htlc.Incoming, true, htlc.RefundTimeout, htlc.RHash,
localCommitKeys)
if err != nil {
return err
}
}
if !isDustRemote {
theirP2WSH, theirWitnessScript, err = lc.genHtlcScript(
htlc.Incoming, false, htlc.RefundTimeout, htlc.RHash,
remoteCommitKeys)
if err != nil {
return err
}
}
pd := &PaymentDescriptor{
RHash: htlc.RHash,
Timeout: htlc.RefundTimeout,
Amount: htlc.Amt,
EntryType: Add,
addCommitHeightRemote: pastHeight,
addCommitHeightLocal: pastHeight,
ourPkScript: ourP2WSH,
ourWitnessScript: ourWitnessScript,
theirPkScript: theirP2WSH,
theirWitnessScript: theirWitnessScript,
}
if !htlc.Incoming {
pd.HtlcIndex = ourCounter
lc.localUpdateLog.appendHtlc(pd)
ourCounter++
} else {
pd.HtlcIndex = theirCounter
lc.remoteUpdateLog.appendHtlc(pd)
lc.rHashMap[pd.RHash] = append(lc.rHashMap[pd.RHash], pd)
theirCounter++
}
}
lc.localCommitChain.tail().ourMessageIndex = ourCounter
lc.localCommitChain.tail().theirMessageIndex = theirCounter
lc.remoteCommitChain.tail().ourMessageIndex = ourCounter
lc.remoteCommitChain.tail().theirMessageIndex = theirCounter
return nil
}
// htlcView represents the "active" HTLCs at a particular point within the
// history of the HTLC update log.
type htlcView struct {
ourUpdates []*PaymentDescriptor
theirUpdates []*PaymentDescriptor
}
2016-07-06 03:01:55 +03:00
// fetchHTLCView returns all the candidate HTLC updates which should be
// considered for inclusion within a commitment based on the passed HTLC log
// indexes.
lnwallet: update state machine to the version within the spec This commit updates the internal channel state machine to the one as described within the spec and currently implemented within the rest of the other Lightning implementations. At a high level the following modifications have been made: * When signing we no loner include the index of the remote party’s log that our signature covers. Instead we include ALL of our current updates, but only the updates of the remote party that we’ve ACK’d. * A pending change is considered ACK’d once a revocation message has been received, locking in the changes in the remote party’s commitment transaction. * When sending a new commitment, we remember the index of our log at that point so we can mark that portion of the log as ACK’d once we receive a revocation message from the remote party. * When receiving a new commitment signature, we include ALL of the remote party’s changes that we’ve received but only our set of changes that’ve been ACK’d by the remote party. * Implicitly a revocation message now also implicitly serves to ACK all the changes that were included in the CommitSig message received before it. The resulting change is a rather minor diff. However, with this state machine it’s important to note that the order to sig/revoke messages has been swapped. A proper exchange now looks like the following: * Alice -> Add, Add, Add * Alice -> Sig * Revoke <- Bob * Sig <- Bob * Alice -> Revoke One other thing that’s worth noting is that with this state machine, since what’s included in an update is implicit, both side may need to at times send a new commitment update in the case of a concurrent state transition initiated by both sides. Finally, all counters/indexes have been made 64-bit integers in order to properly match the spec.
2017-02-21 04:55:33 +03:00
func (lc *LightningChannel) fetchHTLCView(theirLogIndex, ourLogIndex uint64) *htlcView {
var ourHTLCs []*PaymentDescriptor
lnwallet: update state machine to the version within the spec This commit updates the internal channel state machine to the one as described within the spec and currently implemented within the rest of the other Lightning implementations. At a high level the following modifications have been made: * When signing we no loner include the index of the remote party’s log that our signature covers. Instead we include ALL of our current updates, but only the updates of the remote party that we’ve ACK’d. * A pending change is considered ACK’d once a revocation message has been received, locking in the changes in the remote party’s commitment transaction. * When sending a new commitment, we remember the index of our log at that point so we can mark that portion of the log as ACK’d once we receive a revocation message from the remote party. * When receiving a new commitment signature, we include ALL of the remote party’s changes that we’ve received but only our set of changes that’ve been ACK’d by the remote party. * Implicitly a revocation message now also implicitly serves to ACK all the changes that were included in the CommitSig message received before it. The resulting change is a rather minor diff. However, with this state machine it’s important to note that the order to sig/revoke messages has been swapped. A proper exchange now looks like the following: * Alice -> Add, Add, Add * Alice -> Sig * Revoke <- Bob * Sig <- Bob * Alice -> Revoke One other thing that’s worth noting is that with this state machine, since what’s included in an update is implicit, both side may need to at times send a new commitment update in the case of a concurrent state transition initiated by both sides. Finally, all counters/indexes have been made 64-bit integers in order to properly match the spec.
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for e := lc.localUpdateLog.Front(); e != nil; e = e.Next() {
htlc := e.Value.(*PaymentDescriptor)
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// This HTLC is active from this point-of-view iff the log
// index of the state update is below the specified index in
// our update log.
if htlc.LogIndex < ourLogIndex {
ourHTLCs = append(ourHTLCs, htlc)
}
}
var theirHTLCs []*PaymentDescriptor
lnwallet: update state machine to the version within the spec This commit updates the internal channel state machine to the one as described within the spec and currently implemented within the rest of the other Lightning implementations. At a high level the following modifications have been made: * When signing we no loner include the index of the remote party’s log that our signature covers. Instead we include ALL of our current updates, but only the updates of the remote party that we’ve ACK’d. * A pending change is considered ACK’d once a revocation message has been received, locking in the changes in the remote party’s commitment transaction. * When sending a new commitment, we remember the index of our log at that point so we can mark that portion of the log as ACK’d once we receive a revocation message from the remote party. * When receiving a new commitment signature, we include ALL of the remote party’s changes that we’ve received but only our set of changes that’ve been ACK’d by the remote party. * Implicitly a revocation message now also implicitly serves to ACK all the changes that were included in the CommitSig message received before it. The resulting change is a rather minor diff. However, with this state machine it’s important to note that the order to sig/revoke messages has been swapped. A proper exchange now looks like the following: * Alice -> Add, Add, Add * Alice -> Sig * Revoke <- Bob * Sig <- Bob * Alice -> Revoke One other thing that’s worth noting is that with this state machine, since what’s included in an update is implicit, both side may need to at times send a new commitment update in the case of a concurrent state transition initiated by both sides. Finally, all counters/indexes have been made 64-bit integers in order to properly match the spec.
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for e := lc.remoteUpdateLog.Front(); e != nil; e = e.Next() {
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htlc := e.Value.(*PaymentDescriptor)
// If this is an incoming HTLC, then it is only active from
// this point-of-view if the index of the HTLC addition in
// their log is below the specified view index.
if htlc.LogIndex < theirLogIndex {
theirHTLCs = append(theirHTLCs, htlc)
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}
}
return &htlcView{
ourUpdates: ourHTLCs,
theirUpdates: theirHTLCs,
}
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}
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// fetchCommitmentView returns a populated commitment which expresses the state
// of the channel from the point of view of a local or remote chain, evaluating
// the HTLC log up to the passed indexes. This function is used to construct
// both local and remote commitment transactions in order to sign or verify new
// commitment updates. A fully populated commitment is returned which reflects
// the proper balances for both sides at this point in the commitment chain.
func (lc *LightningChannel) fetchCommitmentView(remoteChain bool,
ourLogIndex, theirLogIndex uint64,
keyRing *commitmentKeyRing) (*commitment, error) {
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commitChain := lc.localCommitChain
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if remoteChain {
commitChain = lc.remoteCommitChain
}
ourCommitTx := !remoteChain
ourBalance := commitChain.tip().ourBalance
theirBalance := commitChain.tip().theirBalance
// Add the fee from the previous commitment state back to the
// initiator's balance, so that the fee can be recalculated and
// re-applied in case fee estimation parameters have changed or the
// number of outstanding HTLCs has changed.
if lc.channelState.IsInitiator {
ourBalance += lnwire.NewMSatFromSatoshis(commitChain.tip().fee)
} else if !lc.channelState.IsInitiator {
theirBalance += lnwire.NewMSatFromSatoshis(commitChain.tip().fee)
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}
nextHeight := commitChain.tip().height + 1
// Run through all the HTLCs that will be covered by this transaction
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// in order to update their commitment addition height, and to adjust
// the balances on the commitment transaction accordingly.
// TODO(roasbeef): error if log empty?
htlcView := lc.fetchHTLCView(theirLogIndex, ourLogIndex)
filteredHTLCView := lc.evaluateHTLCView(htlcView, &ourBalance,
&theirBalance, nextHeight, remoteChain)
// Initiate feePerKw to the last committed fee for this chain as we'll
// need this to determine which HTLC's are dust, and also the final fee
// rate.
feePerKw := commitChain.tail().feePerKw
// Check if any fee updates have taken place since that last
// commitment.
if lc.channelState.IsInitiator {
switch {
// We've sent an update_fee message since our last commitment,
// and now are now creating a commitment that reflects the new
// fee update.
case remoteChain && lc.pendingFeeUpdate != nil:
feePerKw = *lc.pendingFeeUpdate
// We've created a new commitment for the remote chain that
// includes a fee update, and have not received a commitment
// after the fee update has been ACked.
case !remoteChain && lc.pendingAckFeeUpdate != nil:
feePerKw = *lc.pendingAckFeeUpdate
}
} else {
switch {
// We've received a fee update since the last local commitment,
// so we'll include the fee update in the current view.
case !remoteChain && lc.pendingFeeUpdate != nil:
feePerKw = *lc.pendingFeeUpdate
// Earlier we received a commitment that signed an earlier fee
// update, and now we must ACK that update.
case remoteChain && lc.pendingAckFeeUpdate != nil:
feePerKw = *lc.pendingAckFeeUpdate
}
}
// Determine how many current HTLCs are over the dust limit, and should
// be counted for the purpose of fee calculation.
var dustLimit btcutil.Amount
if remoteChain {
dustLimit = lc.remoteChanCfg.DustLimit
} else {
dustLimit = lc.localChanCfg.DustLimit
}
c := &commitment{
height: nextHeight,
ourBalance: ourBalance,
ourMessageIndex: ourLogIndex,
theirMessageIndex: theirLogIndex,
theirBalance: theirBalance,
feePerKw: feePerKw,
dustLimit: dustLimit,
isOurs: !remoteChain,
}
// Actually generate unsigned commitment transaction for this view.
if err := lc.createCommitmentTx(c, filteredHTLCView, keyRing); err != nil {
return nil, err
}
// In order to ensure _none_ of the HTLC's associated with this new
// commitment are mutated, we'll manually copy over each HTLC to its
// respective slice.
c.outgoingHTLCs = make([]PaymentDescriptor, len(filteredHTLCView.ourUpdates))
for i, htlc := range filteredHTLCView.ourUpdates {
c.outgoingHTLCs[i] = *htlc
}
c.incomingHTLCs = make([]PaymentDescriptor, len(filteredHTLCView.theirUpdates))
for i, htlc := range filteredHTLCView.theirUpdates {
c.incomingHTLCs[i] = *htlc
}
// Finally, we'll populate all the HTLC indexes so we can track the
// locations of each HTLC in the commitment state.
if err := c.populateHtlcIndexes(ourCommitTx, dustLimit); err != nil {
return nil, err
}
return c, nil
}
// createCommitmentTx generates the unsigned commitment transaction for a
// commitment view and assigns to txn field.
func (lc *LightningChannel) createCommitmentTx(c *commitment,
filteredHTLCView *htlcView, keyRing *commitmentKeyRing) error {
ourBalance := c.ourBalance
theirBalance := c.theirBalance
numHTLCs := int64(0)
for _, htlc := range filteredHTLCView.ourUpdates {
if htlcIsDust(false, c.isOurs, c.feePerKw,
htlc.Amount.ToSatoshis(), c.dustLimit) {
continue
}
numHTLCs++
}
for _, htlc := range filteredHTLCView.theirUpdates {
if htlcIsDust(true, c.isOurs, c.feePerKw,
htlc.Amount.ToSatoshis(), c.dustLimit) {
continue
}
numHTLCs++
}
// Next, we'll calculate the fee for the commitment transaction based
// on its total weight. Once we have the total weight, we'll multiply
// by the current fee-per-kw, then divide by 1000 to get the proper
// fee.
totalCommitWeight := commitWeight + (htlcWeight * numHTLCs)
// With the weight known, we can now calculate the commitment fee,
// ensuring that we account for any dust outputs trimmed above.
commitFee := btcutil.Amount((int64(c.feePerKw) * totalCommitWeight) / 1000)
// Currently, within the protocol, the initiator always pays the fees.
// So we'll subtract the fee amount from the balance of the current
// initiator.
if lc.channelState.IsInitiator {
ourBalance -= lnwire.NewMSatFromSatoshis(commitFee)
} else if !lc.channelState.IsInitiator {
theirBalance -= lnwire.NewMSatFromSatoshis(commitFee)
}
var (
delay uint32
delayBalance, p2wkhBalance btcutil.Amount
)
if c.isOurs {
delay = uint32(lc.localChanCfg.CsvDelay)
delayBalance = ourBalance.ToSatoshis()
p2wkhBalance = theirBalance.ToSatoshis()
} else {
delay = uint32(lc.remoteChanCfg.CsvDelay)
delayBalance = theirBalance.ToSatoshis()
p2wkhBalance = ourBalance.ToSatoshis()
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}
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// Generate a new commitment transaction with all the latest
// unsettled/un-timed out HTLCs.
commitTx, err := CreateCommitTx(lc.fundingTxIn, keyRing, delay,
delayBalance, p2wkhBalance, c.dustLimit)
if err != nil {
return err
}
// We'll now add all the HTLC outputs to the commitment transaction.
// Each output includes an off-chain 2-of-2 covenant clause, so we'll
// need the objective local/remote keys for this particular commitment
// as well.
for _, htlc := range filteredHTLCView.ourUpdates {
if htlcIsDust(false, c.isOurs, c.feePerKw,
htlc.Amount.ToSatoshis(), c.dustLimit) {
continue
}
err := lc.addHTLC(commitTx, c.isOurs, false, htlc, keyRing)
if err != nil {
return err
}
}
for _, htlc := range filteredHTLCView.theirUpdates {
if htlcIsDust(true, c.isOurs, c.feePerKw,
htlc.Amount.ToSatoshis(), c.dustLimit) {
continue
}
err := lc.addHTLC(commitTx, c.isOurs, true, htlc, keyRing)
if err != nil {
return err
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}
}
// Set the state hint of the commitment transaction to facilitate
// quickly recovering the necessary penalty state in the case of an
// uncooperative broadcast.
err = SetStateNumHint(commitTx, c.height, lc.stateHintObsfucator)
if err != nil {
return err
}
// Sort the transactions according to the agreed upon canonical
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// ordering. This lets us skip sending the entire transaction over,
// instead we'll just send signatures.
txsort.InPlaceSort(commitTx)
c.txn = commitTx
c.fee = commitFee
c.ourBalance = ourBalance
c.theirBalance = theirBalance
return nil
}
// evaluateHTLCView processes all update entries in both HTLC update logs,
// producing a final view which is the result of properly applying all adds,
// settles, and timeouts found in both logs. The resulting view returned
// reflects the current state of HTLCs within the remote or local commitment
// chain.
func (lc *LightningChannel) evaluateHTLCView(view *htlcView, ourBalance,
theirBalance *lnwire.MilliSatoshi, nextHeight uint64, remoteChain bool) *htlcView {
newView := &htlcView{}
// We use two maps, one for the local log and one for the remote log to
// keep track of which entries we need to skip when creating the final
// htlc view. We skip an entry whenever we find a settle or a timeout
// modifying an entry.
lnwallet: update state machine to the version within the spec This commit updates the internal channel state machine to the one as described within the spec and currently implemented within the rest of the other Lightning implementations. At a high level the following modifications have been made: * When signing we no loner include the index of the remote party’s log that our signature covers. Instead we include ALL of our current updates, but only the updates of the remote party that we’ve ACK’d. * A pending change is considered ACK’d once a revocation message has been received, locking in the changes in the remote party’s commitment transaction. * When sending a new commitment, we remember the index of our log at that point so we can mark that portion of the log as ACK’d once we receive a revocation message from the remote party. * When receiving a new commitment signature, we include ALL of the remote party’s changes that we’ve received but only our set of changes that’ve been ACK’d by the remote party. * Implicitly a revocation message now also implicitly serves to ACK all the changes that were included in the CommitSig message received before it. The resulting change is a rather minor diff. However, with this state machine it’s important to note that the order to sig/revoke messages has been swapped. A proper exchange now looks like the following: * Alice -> Add, Add, Add * Alice -> Sig * Revoke <- Bob * Sig <- Bob * Alice -> Revoke One other thing that’s worth noting is that with this state machine, since what’s included in an update is implicit, both side may need to at times send a new commitment update in the case of a concurrent state transition initiated by both sides. Finally, all counters/indexes have been made 64-bit integers in order to properly match the spec.
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skipUs := make(map[uint64]struct{})
skipThem := make(map[uint64]struct{})
// First we run through non-add entries in both logs, populating the
// skip sets and mutating the current chain state (crediting balances,
// etc) to reflect the settle/timeout entry encountered.
for _, entry := range view.ourUpdates {
if entry.EntryType == Add {
continue
}
// If we're settling in inbound HTLC, and it hasn't been
// processed, yet, the increment our state tracking the total
// number of satoshis we've received within the channel.
if entry.EntryType == Settle && !remoteChain &&
entry.removeCommitHeightLocal == 0 {
lc.channelState.TotalMSatReceived += entry.Amount
}
addEntry := lc.remoteUpdateLog.lookupHtlc(entry.ParentIndex)
skipThem[addEntry.HtlcIndex] = struct{}{}
processRemoveEntry(entry, ourBalance, theirBalance,
nextHeight, remoteChain, true)
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}
for _, entry := range view.theirUpdates {
if entry.EntryType == Add {
continue
}
// If the remote party is settling one of our outbound HTLC's,
// and it hasn't been processed, yet, the increment our state
// tracking the total number of satoshis we've sent within the
// channel.
if entry.EntryType == Settle && !remoteChain &&
entry.removeCommitHeightLocal == 0 {
lc.channelState.TotalMSatSent += entry.Amount
}
addEntry := lc.localUpdateLog.lookupHtlc(entry.ParentIndex)
skipUs[addEntry.HtlcIndex] = struct{}{}
processRemoveEntry(entry, ourBalance, theirBalance,
nextHeight, remoteChain, false)
}
// Next we take a second pass through all the log entries, skipping any
// settled HTLCs, and debiting the chain state balance due to any newly
// added HTLCs.
for _, entry := range view.ourUpdates {
isAdd := entry.EntryType == Add
if _, ok := skipUs[entry.HtlcIndex]; !isAdd || ok {
continue
}
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processAddEntry(entry, ourBalance, theirBalance, nextHeight,
remoteChain, false)
newView.ourUpdates = append(newView.ourUpdates, entry)
}
for _, entry := range view.theirUpdates {
isAdd := entry.EntryType == Add
if _, ok := skipThem[entry.HtlcIndex]; !isAdd || ok {
continue
}
processAddEntry(entry, ourBalance, theirBalance, nextHeight,
remoteChain, true)
newView.theirUpdates = append(newView.theirUpdates, entry)
}
return newView
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}
// processAddEntry evaluates the effect of an add entry within the HTLC log.
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// If the HTLC hasn't yet been committed in either chain, then the height it
// was committed is updated. Keeping track of this inclusion height allows us to
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// later compact the log once the change is fully committed in both chains.
func processAddEntry(htlc *PaymentDescriptor, ourBalance, theirBalance *lnwire.MilliSatoshi,
nextHeight uint64, remoteChain bool, isIncoming bool) {
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// If we're evaluating this entry for the remote chain (to create/view
// a new commitment), then we'll may be updating the height this entry
// was added to the chain. Otherwise, we may be updating the entry's
// height w.r.t the local chain.
var addHeight *uint64
if remoteChain {
addHeight = &htlc.addCommitHeightRemote
} else {
addHeight = &htlc.addCommitHeightLocal
}
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if *addHeight != 0 {
return
}
if isIncoming {
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// If this is a new incoming (un-committed) HTLC, then we need
// to update their balance accordingly by subtracting the
// amount of the HTLC that are funds pending.
*theirBalance -= htlc.Amount
} else {
// Similarly, we need to debit our balance if this is an out
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// going HTLC to reflect the pending balance.
*ourBalance -= htlc.Amount
}
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*addHeight = nextHeight
}
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// processRemoveEntry processes a log entry which settles or timesout a
// previously added HTLC. If the removal entry has already been processed, it
// is skipped.
func processRemoveEntry(htlc *PaymentDescriptor, ourBalance,
theirBalance *lnwire.MilliSatoshi, nextHeight uint64,
remoteChain bool, isIncoming bool) {
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var removeHeight *uint64
if remoteChain {
removeHeight = &htlc.removeCommitHeightRemote
} else {
removeHeight = &htlc.removeCommitHeightLocal
}
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// Ignore any removal entries which have already been processed.
if *removeHeight != 0 {
return
}
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switch {
// If an incoming HTLC is being settled, then this means that we've
// received the preimage either from another subsystem, or the
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// upstream peer in the route. Therefore, we increase our balance by
// the HTLC amount.
case isIncoming && htlc.EntryType == Settle:
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*ourBalance += htlc.Amount
lnwallet: update state machine to the version within the spec This commit updates the internal channel state machine to the one as described within the spec and currently implemented within the rest of the other Lightning implementations. At a high level the following modifications have been made: * When signing we no loner include the index of the remote party’s log that our signature covers. Instead we include ALL of our current updates, but only the updates of the remote party that we’ve ACK’d. * A pending change is considered ACK’d once a revocation message has been received, locking in the changes in the remote party’s commitment transaction. * When sending a new commitment, we remember the index of our log at that point so we can mark that portion of the log as ACK’d once we receive a revocation message from the remote party. * When receiving a new commitment signature, we include ALL of the remote party’s changes that we’ve received but only our set of changes that’ve been ACK’d by the remote party. * Implicitly a revocation message now also implicitly serves to ACK all the changes that were included in the CommitSig message received before it. The resulting change is a rather minor diff. However, with this state machine it’s important to note that the order to sig/revoke messages has been swapped. A proper exchange now looks like the following: * Alice -> Add, Add, Add * Alice -> Sig * Revoke <- Bob * Sig <- Bob * Alice -> Revoke One other thing that’s worth noting is that with this state machine, since what’s included in an update is implicit, both side may need to at times send a new commitment update in the case of a concurrent state transition initiated by both sides. Finally, all counters/indexes have been made 64-bit integers in order to properly match the spec.
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// Otherwise, this HTLC is being failed out, therefore the value of the
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// HTLC should return to the remote party.
lnwallet: update state machine to the version within the spec This commit updates the internal channel state machine to the one as described within the spec and currently implemented within the rest of the other Lightning implementations. At a high level the following modifications have been made: * When signing we no loner include the index of the remote party’s log that our signature covers. Instead we include ALL of our current updates, but only the updates of the remote party that we’ve ACK’d. * A pending change is considered ACK’d once a revocation message has been received, locking in the changes in the remote party’s commitment transaction. * When sending a new commitment, we remember the index of our log at that point so we can mark that portion of the log as ACK’d once we receive a revocation message from the remote party. * When receiving a new commitment signature, we include ALL of the remote party’s changes that we’ve received but only our set of changes that’ve been ACK’d by the remote party. * Implicitly a revocation message now also implicitly serves to ACK all the changes that were included in the CommitSig message received before it. The resulting change is a rather minor diff. However, with this state machine it’s important to note that the order to sig/revoke messages has been swapped. A proper exchange now looks like the following: * Alice -> Add, Add, Add * Alice -> Sig * Revoke <- Bob * Sig <- Bob * Alice -> Revoke One other thing that’s worth noting is that with this state machine, since what’s included in an update is implicit, both side may need to at times send a new commitment update in the case of a concurrent state transition initiated by both sides. Finally, all counters/indexes have been made 64-bit integers in order to properly match the spec.
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case isIncoming && htlc.EntryType == Fail:
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*theirBalance += htlc.Amount
lnwallet: update state machine to the version within the spec This commit updates the internal channel state machine to the one as described within the spec and currently implemented within the rest of the other Lightning implementations. At a high level the following modifications have been made: * When signing we no loner include the index of the remote party’s log that our signature covers. Instead we include ALL of our current updates, but only the updates of the remote party that we’ve ACK’d. * A pending change is considered ACK’d once a revocation message has been received, locking in the changes in the remote party’s commitment transaction. * When sending a new commitment, we remember the index of our log at that point so we can mark that portion of the log as ACK’d once we receive a revocation message from the remote party. * When receiving a new commitment signature, we include ALL of the remote party’s changes that we’ve received but only our set of changes that’ve been ACK’d by the remote party. * Implicitly a revocation message now also implicitly serves to ACK all the changes that were included in the CommitSig message received before it. The resulting change is a rather minor diff. However, with this state machine it’s important to note that the order to sig/revoke messages has been swapped. A proper exchange now looks like the following: * Alice -> Add, Add, Add * Alice -> Sig * Revoke <- Bob * Sig <- Bob * Alice -> Revoke One other thing that’s worth noting is that with this state machine, since what’s included in an update is implicit, both side may need to at times send a new commitment update in the case of a concurrent state transition initiated by both sides. Finally, all counters/indexes have been made 64-bit integers in order to properly match the spec.
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// If an outgoing HTLC is being settled, then this means that the
// downstream party resented the preimage or learned of it via a
// downstream peer. In either case, we credit their settled value with
// the value of the HTLC.
case !isIncoming && htlc.EntryType == Settle:
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*theirBalance += htlc.Amount
lnwallet: update state machine to the version within the spec This commit updates the internal channel state machine to the one as described within the spec and currently implemented within the rest of the other Lightning implementations. At a high level the following modifications have been made: * When signing we no loner include the index of the remote party’s log that our signature covers. Instead we include ALL of our current updates, but only the updates of the remote party that we’ve ACK’d. * A pending change is considered ACK’d once a revocation message has been received, locking in the changes in the remote party’s commitment transaction. * When sending a new commitment, we remember the index of our log at that point so we can mark that portion of the log as ACK’d once we receive a revocation message from the remote party. * When receiving a new commitment signature, we include ALL of the remote party’s changes that we’ve received but only our set of changes that’ve been ACK’d by the remote party. * Implicitly a revocation message now also implicitly serves to ACK all the changes that were included in the CommitSig message received before it. The resulting change is a rather minor diff. However, with this state machine it’s important to note that the order to sig/revoke messages has been swapped. A proper exchange now looks like the following: * Alice -> Add, Add, Add * Alice -> Sig * Revoke <- Bob * Sig <- Bob * Alice -> Revoke One other thing that’s worth noting is that with this state machine, since what’s included in an update is implicit, both side may need to at times send a new commitment update in the case of a concurrent state transition initiated by both sides. Finally, all counters/indexes have been made 64-bit integers in order to properly match the spec.
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// Otherwise, one of our outgoing HTLC's has timed out, so the value of
// the HTLC should be returned to our settled balance.
case !isIncoming && htlc.EntryType == Fail:
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*ourBalance += htlc.Amount
}
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*removeHeight = nextHeight
}
// generateRemoteHtlcSigJobs generates a series of HTLC signature jobs for the
// sig pool, along with a channel that if closed, will cancel any jobs after
// they have been submitted to the sigPool. This method is to be used when
// generating a new commitment for the remote party. The jobs generated by the
// signature can be submitted to the sigPool to generate all the signatures
// asynchronously and in parallel.
func genRemoteHtlcSigJobs(keyRing *commitmentKeyRing,
localChanCfg, remoteChanCfg *channeldb.ChannelConfig,
remoteCommitView *commitment) ([]signJob, chan struct{}, error) {
txHash := remoteCommitView.txn.TxHash()
dustLimit := localChanCfg.DustLimit
feePerKw := remoteCommitView.feePerKw
// With the keys generated, we'll make a slice with enough capacity to
// hold potentially all the HTLC's. The actual slice may be a bit
// smaller (than its total capacity) an some HTLC's may be dust.
numSigs := (len(remoteCommitView.incomingHTLCs) +
len(remoteCommitView.outgoingHTLCs))
sigBatch := make([]signJob, 0, numSigs)
var err error
cancelChan := make(chan struct{})
// For ech outgoing and incoming HTLC, if the HTLC isn't considered a
// dust output after taking into account second-level HTLC fees, then a
// sigJob will be generated and appended to the current batch.
for _, htlc := range remoteCommitView.incomingHTLCs {
if htlcIsDust(true, false, feePerKw, htlc.Amount.ToSatoshis(),
dustLimit) {
continue
}
// If the HTLC isn't dust, then we'll create an empty sign job
// to add to the batch momentarily.
sigJob := signJob{}
sigJob.cancel = cancelChan
sigJob.resp = make(chan signJobResp, 1)
// As this is an incoming HTLC and we're sinning the commitment
// transaction of the remote node, we'll need to generate an
// HTLC timeout transaction for them. The output of the timeout
// transaction needs to account for fees, so we'll compute the
// required fee and output now.
htlcFee := htlcTimeoutFee(feePerKw)
outputAmt := htlc.Amount.ToSatoshis() - htlcFee
// With the fee calculate, we can properly create the HTLC
// timeout transaction using the HTLC amount minus the fee.
op := wire.OutPoint{
Hash: txHash,
Index: uint32(htlc.remoteOutputIndex),
}
sigJob.tx, err = createHtlcTimeoutTx(op, outputAmt,
htlc.Timeout, uint32(remoteChanCfg.CsvDelay),
keyRing.revocationKey, keyRing.delayKey)
if err != nil {
return nil, nil, err
}
// Finally, we'll generate a sign descriptor to generate a
// signature to give to the remote party for this commitment
// transaction. Note we use the raw HTLC amount.
sigJob.signDesc = SignDescriptor{
PubKey: localChanCfg.PaymentBasePoint,
SingleTweak: keyRing.localKeyTweak,
WitnessScript: htlc.theirWitnessScript,
Output: &wire.TxOut{
Value: int64(htlc.Amount.ToSatoshis()),
},
HashType: txscript.SigHashAll,
SigHashes: txscript.NewTxSigHashes(sigJob.tx),
InputIndex: 0,
}
sigJob.outputIndex = htlc.remoteOutputIndex
sigBatch = append(sigBatch, sigJob)
}
for _, htlc := range remoteCommitView.outgoingHTLCs {
if htlcIsDust(false, false, feePerKw, htlc.Amount.ToSatoshis(),
dustLimit) {
continue
}
sigJob := signJob{}
sigJob.cancel = cancelChan
sigJob.resp = make(chan signJobResp, 1)
// As this is an outgoing HTLC and we're signing the commitment
// transaction of the remote node, we'll need to generate an
// HTLC success transaction for them. The output of the timeout
// transaction needs to account for fees, so we'll compute the
// required fee and output now.
htlcFee := htlcSuccessFee(feePerKw)
outputAmt := htlc.Amount.ToSatoshis() - htlcFee
// With the proper output amount calculated, we can now
// generate the success transaction using the remote party's
// CSV delay.
op := wire.OutPoint{
Hash: txHash,
Index: uint32(htlc.remoteOutputIndex),
}
sigJob.tx, err = createHtlcSuccessTx(op, outputAmt,
uint32(remoteChanCfg.CsvDelay), keyRing.revocationKey,
keyRing.delayKey)
if err != nil {
return nil, nil, err
}
// Finally, we'll generate a sign descriptor to generate a
// signature to give to the remote party for this commitment
// transaction. Note we use the raw HTLC amount.
sigJob.signDesc = SignDescriptor{
PubKey: localChanCfg.PaymentBasePoint,
SingleTweak: keyRing.localKeyTweak,
WitnessScript: htlc.theirWitnessScript,
Output: &wire.TxOut{
Value: int64(htlc.Amount.ToSatoshis()),
},
HashType: txscript.SigHashAll,
SigHashes: txscript.NewTxSigHashes(sigJob.tx),
InputIndex: 0,
}
sigJob.outputIndex = htlc.remoteOutputIndex
sigBatch = append(sigBatch, sigJob)
}
return sigBatch, cancelChan, nil
}
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// SignNextCommitment signs a new commitment which includes any previous
// unsettled HTLCs, any new HTLCs, and any modifications to prior HTLCs
// committed in previous commitment updates. Signing a new commitment
// decrements the available revocation window by 1. After a successful method
// call, the remote party's commitment chain is extended by a new commitment
// which includes all updates to the HTLC log prior to this method invocation.
// The first return parameter is the signature for the commitment
// transaction itself, while the second parameter is a slice of all
// HTLC signatures (if any). The HTLC signatures are sorted according to
// the BIP 69 order of the HTLC's on the commitment transaction.
func (lc *LightningChannel) SignNextCommitment() (*btcec.Signature, []*btcec.Signature, error) {
lc.Lock()
defer lc.Unlock()
lnwallet: update state machine to the version within the spec This commit updates the internal channel state machine to the one as described within the spec and currently implemented within the rest of the other Lightning implementations. At a high level the following modifications have been made: * When signing we no loner include the index of the remote party’s log that our signature covers. Instead we include ALL of our current updates, but only the updates of the remote party that we’ve ACK’d. * A pending change is considered ACK’d once a revocation message has been received, locking in the changes in the remote party’s commitment transaction. * When sending a new commitment, we remember the index of our log at that point so we can mark that portion of the log as ACK’d once we receive a revocation message from the remote party. * When receiving a new commitment signature, we include ALL of the remote party’s changes that we’ve received but only our set of changes that’ve been ACK’d by the remote party. * Implicitly a revocation message now also implicitly serves to ACK all the changes that were included in the CommitSig message received before it. The resulting change is a rather minor diff. However, with this state machine it’s important to note that the order to sig/revoke messages has been swapped. A proper exchange now looks like the following: * Alice -> Add, Add, Add * Alice -> Sig * Revoke <- Bob * Sig <- Bob * Alice -> Revoke One other thing that’s worth noting is that with this state machine, since what’s included in an update is implicit, both side may need to at times send a new commitment update in the case of a concurrent state transition initiated by both sides. Finally, all counters/indexes have been made 64-bit integers in order to properly match the spec.
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// If we're awaiting an ACK to a commitment signature, then we're
// unable to create new states as we don't have any revocations we can
// use.
if lc.pendingACK {
return nil, nil, ErrNoWindow
lnwallet: update state machine to the version within the spec This commit updates the internal channel state machine to the one as described within the spec and currently implemented within the rest of the other Lightning implementations. At a high level the following modifications have been made: * When signing we no loner include the index of the remote party’s log that our signature covers. Instead we include ALL of our current updates, but only the updates of the remote party that we’ve ACK’d. * A pending change is considered ACK’d once a revocation message has been received, locking in the changes in the remote party’s commitment transaction. * When sending a new commitment, we remember the index of our log at that point so we can mark that portion of the log as ACK’d once we receive a revocation message from the remote party. * When receiving a new commitment signature, we include ALL of the remote party’s changes that we’ve received but only our set of changes that’ve been ACK’d by the remote party. * Implicitly a revocation message now also implicitly serves to ACK all the changes that were included in the CommitSig message received before it. The resulting change is a rather minor diff. However, with this state machine it’s important to note that the order to sig/revoke messages has been swapped. A proper exchange now looks like the following: * Alice -> Add, Add, Add * Alice -> Sig * Revoke <- Bob * Sig <- Bob * Alice -> Revoke One other thing that’s worth noting is that with this state machine, since what’s included in an update is implicit, both side may need to at times send a new commitment update in the case of a concurrent state transition initiated by both sides. Finally, all counters/indexes have been made 64-bit integers in order to properly match the spec.
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}
// Before we extend this new commitment to the remote commitment chain,
// ensure that we aren't violating any of the constraints the remote
// party set up when we initially set up the channel. If we are, then
// we'll abort this state transition.
err := lc.validateCommitmentSanity(lc.remoteUpdateLog.ackedIndex,
lc.localUpdateLog.logIndex, false, true, true)
lnwallet: update state machine to the version within the spec This commit updates the internal channel state machine to the one as described within the spec and currently implemented within the rest of the other Lightning implementations. At a high level the following modifications have been made: * When signing we no loner include the index of the remote party’s log that our signature covers. Instead we include ALL of our current updates, but only the updates of the remote party that we’ve ACK’d. * A pending change is considered ACK’d once a revocation message has been received, locking in the changes in the remote party’s commitment transaction. * When sending a new commitment, we remember the index of our log at that point so we can mark that portion of the log as ACK’d once we receive a revocation message from the remote party. * When receiving a new commitment signature, we include ALL of the remote party’s changes that we’ve received but only our set of changes that’ve been ACK’d by the remote party. * Implicitly a revocation message now also implicitly serves to ACK all the changes that were included in the CommitSig message received before it. The resulting change is a rather minor diff. However, with this state machine it’s important to note that the order to sig/revoke messages has been swapped. A proper exchange now looks like the following: * Alice -> Add, Add, Add * Alice -> Sig * Revoke <- Bob * Sig <- Bob * Alice -> Revoke One other thing that’s worth noting is that with this state machine, since what’s included in an update is implicit, both side may need to at times send a new commitment update in the case of a concurrent state transition initiated by both sides. Finally, all counters/indexes have been made 64-bit integers in order to properly match the spec.
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if err != nil {
return nil, nil, err
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}
// Grab the next commitment point for the remote party. This will be
// used within fetchCommitmentView to derive all the keys necessary to
// construct the commitment state.
commitPoint := lc.channelState.RemoteNextRevocation
keyRing := deriveCommitmentKeys(commitPoint, false, lc.localChanCfg,
lc.remoteChanCfg)
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// Create a new commitment view which will calculate the evaluated
// state of the remote node's new commitment including our latest added
// HTLCs. The view includes the latest balances for both sides on the
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// remote node's chain, and also update the addition height of any new
lnwallet: update state machine to the version within the spec This commit updates the internal channel state machine to the one as described within the spec and currently implemented within the rest of the other Lightning implementations. At a high level the following modifications have been made: * When signing we no loner include the index of the remote party’s log that our signature covers. Instead we include ALL of our current updates, but only the updates of the remote party that we’ve ACK’d. * A pending change is considered ACK’d once a revocation message has been received, locking in the changes in the remote party’s commitment transaction. * When sending a new commitment, we remember the index of our log at that point so we can mark that portion of the log as ACK’d once we receive a revocation message from the remote party. * When receiving a new commitment signature, we include ALL of the remote party’s changes that we’ve received but only our set of changes that’ve been ACK’d by the remote party. * Implicitly a revocation message now also implicitly serves to ACK all the changes that were included in the CommitSig message received before it. The resulting change is a rather minor diff. However, with this state machine it’s important to note that the order to sig/revoke messages has been swapped. A proper exchange now looks like the following: * Alice -> Add, Add, Add * Alice -> Sig * Revoke <- Bob * Sig <- Bob * Alice -> Revoke One other thing that’s worth noting is that with this state machine, since what’s included in an update is implicit, both side may need to at times send a new commitment update in the case of a concurrent state transition initiated by both sides. Finally, all counters/indexes have been made 64-bit integers in order to properly match the spec.
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// HTLC log entries. When we creating a new remote view, we include
// _all_ of our changes (pending or committed) but only the remote
// node's changes up to the last change we've ACK'd.
newCommitView, err := lc.fetchCommitmentView(true,
lc.localUpdateLog.logIndex, lc.remoteUpdateLog.ackedIndex, keyRing)
if err != nil {
return nil, nil, err
}
walletLog.Tracef("ChannelPoint(%v): extending remote chain to height %v",
lc.channelState.FundingOutpoint, newCommitView.height)
walletLog.Tracef("ChannelPoint(%v): remote chain: our_balance=%v, "+
"their_balance=%v, commit_tx: %v",
lc.channelState.FundingOutpoint, newCommitView.ourBalance,
newCommitView.theirBalance,
newLogClosure(func() string {
return spew.Sdump(newCommitView.txn)
}),
)
// With the commitment view constructed, if there are any HTLC's, we'll
// need to generate signatures of each of them for the remote party's
// commitment state. We do so in two phases: first we generate and
// submit the set of signature jobs to the worker pool.
sigBatch, cancelChan, err := genRemoteHtlcSigJobs(keyRing,
lc.localChanCfg, lc.remoteChanCfg, newCommitView,
)
if err != nil {
return nil, nil, err
}
lc.sigPool.SubmitSignBatch(sigBatch)
// While the jobs are being carried out, we'll Sign their version of
// the new commitment transaction while we're waiting for the rest of
// the HTLC signatures to be processed.
lc.signDesc.SigHashes = txscript.NewTxSigHashes(newCommitView.txn)
rawSig, err := lc.signer.SignOutputRaw(newCommitView.txn, lc.signDesc)
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if err != nil {
close(cancelChan)
return nil, nil, err
}
sig, err := btcec.ParseSignature(rawSig, btcec.S256())
if err != nil {
close(cancelChan)
return nil, nil, err
}
// We'll need to send over the signatures to the remote party in the
// order as they appear on the commitment transaction after BIP 69
// sorting.
sort.Slice(sigBatch, func(i, j int) bool {
return sigBatch[i].outputIndex < sigBatch[j].outputIndex
})
// With the jobs sorted, we'll now iterate through all the responses to
// gather each of the signatures in order.
htlcSigs := make([]*btcec.Signature, 0, len(sigBatch))
for _, htlcSigJob := range sigBatch {
jobResp := <-htlcSigJob.resp
// If an error occurred, then we'll cancel any other active
// jobs.
if jobResp.err != nil {
close(cancelChan)
return nil, nil, err
}
htlcSigs = append(htlcSigs, jobResp.sig)
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}
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// Extend the remote commitment chain by one with the addition of our
// latest commitment update.
lc.remoteCommitChain.addCommitment(newCommitView)
// If we are the channel initiator then we would have signed any sent
// fee update at this point, so mark this update as pending ACK, and
// set pendingFeeUpdate to nil. We can do this since we know we won't
// sign any new commitment before receiving a revoke_and_ack, because
// of the revocation window of 1.
if lc.channelState.IsInitiator {
lc.pendingAckFeeUpdate = lc.pendingFeeUpdate
lc.pendingFeeUpdate = nil
}
lnwallet: update state machine to the version within the spec This commit updates the internal channel state machine to the one as described within the spec and currently implemented within the rest of the other Lightning implementations. At a high level the following modifications have been made: * When signing we no loner include the index of the remote party’s log that our signature covers. Instead we include ALL of our current updates, but only the updates of the remote party that we’ve ACK’d. * A pending change is considered ACK’d once a revocation message has been received, locking in the changes in the remote party’s commitment transaction. * When sending a new commitment, we remember the index of our log at that point so we can mark that portion of the log as ACK’d once we receive a revocation message from the remote party. * When receiving a new commitment signature, we include ALL of the remote party’s changes that we’ve received but only our set of changes that’ve been ACK’d by the remote party. * Implicitly a revocation message now also implicitly serves to ACK all the changes that were included in the CommitSig message received before it. The resulting change is a rather minor diff. However, with this state machine it’s important to note that the order to sig/revoke messages has been swapped. A proper exchange now looks like the following: * Alice -> Add, Add, Add * Alice -> Sig * Revoke <- Bob * Sig <- Bob * Alice -> Revoke One other thing that’s worth noting is that with this state machine, since what’s included in an update is implicit, both side may need to at times send a new commitment update in the case of a concurrent state transition initiated by both sides. Finally, all counters/indexes have been made 64-bit integers in order to properly match the spec.
2017-02-21 04:55:33 +03:00
// As we've just created a new update for the remote commitment chain,
// we set the bool indicating that we're waiting for an ACK to our new
// changes.
lc.pendingACK = true
// Additionally, we'll remember our log index at this point, so we can
// properly track which changes have been ACK'd.
lc.localUpdateLog.initiateTransition()
return sig, htlcSigs, nil
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}
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// validateCommitmentSanity is used to validate that on current state the commitment
// transaction is valid in terms of propagating it over Bitcoin network, and
// also that all outputs are meet Bitcoin spec requirements and they are
// spendable.
func (lc *LightningChannel) validateCommitmentSanity(theirLogCounter,
ourLogCounter uint64, prediction bool, local bool, remote bool) error {
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// TODO(roasbeef): verify remaining sanity requirements
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htlcCount := 0
// If we adding or receiving the htlc we increase the number of htlcs
// by one in order to not overflow the commitment transaction by
// insertion.
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if prediction {
htlcCount++
}
// Run through all the HTLCs that will be covered by this transaction
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// in order to calculate theirs count.
view := lc.fetchHTLCView(theirLogCounter, ourLogCounter)
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if remote {
for _, entry := range view.theirUpdates {
if entry.EntryType == Add {
htlcCount++
}
}
for _, entry := range view.ourUpdates {
if entry.EntryType != Add {
htlcCount--
}
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}
}
if local {
for _, entry := range view.ourUpdates {
if entry.EntryType == Add {
htlcCount++
}
}
for _, entry := range view.theirUpdates {
if entry.EntryType != Add {
htlcCount--
}
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}
}
// If we're validating the commitment sanity for HTLC _log_ update by a
// particular side, then we'll only consider half of the available HTLC
// bandwidth. However, if we're validating the _creation_ of a new
// commitment state, then we'll use the full value as the sum of the
// contribution of both sides shouldn't exceed the max number.
var maxHTLCNumber int
if local && remote {
maxHTLCNumber = MaxHTLCNumber
} else {
maxHTLCNumber = MaxHTLCNumber / 2
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}
if htlcCount > maxHTLCNumber {
return ErrMaxHTLCNumber
}
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return nil
}
// genHtlcSigValidationJobs generates a series of signatures verification jobs
// meant to verify all the signatures for HTLC's attached to a newly created
// commitment state. The jobs generated are fully populated, and can be sent
// directly into the pool of workers.
func genHtlcSigValidationJobs(localCommitmentView *commitment,
keyRing *commitmentKeyRing, htlcSigs []*btcec.Signature,
localChanCfg, remoteChanCfg *channeldb.ChannelConfig) []verifyJob {
// If this new commitment state doesn't have any HTLC's that are to be
// signed, then we'll return a nil slice.
if len(htlcSigs) == 0 {
return nil
}
txHash := localCommitmentView.txn.TxHash()
feePerKw := localCommitmentView.feePerKw
// With the required state generated, we'll create a slice with large
// enough capacity to hold verification jobs for all HTLC's in this
// view. In the case that we have some dust outputs, then the actual
// length will be smaller than the total capacity.
numHtlcs := (len(localCommitmentView.incomingHTLCs) +
len(localCommitmentView.outgoingHTLCs))
verifyJobs := make([]verifyJob, 0, numHtlcs)
// We'll iterate through each output in the commitment transaction,
// populating the sigHash closure function if it's detected to be an
// HLTC output. Given the sighash, and the signing key, we'll be able
// to validate each signature within the worker pool.
i := 0
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for index := range localCommitmentView.txn.TxOut {
var sigHash func() ([]byte, error)
outputIndex := int32(index)
switch {
// If this output index is found within the incoming HTLC index,
// then this means that we need to generate an HTLC success
// transaction in order to validate the signature.
case localCommitmentView.incomingHTLCIndex[outputIndex] != nil:
htlc := localCommitmentView.incomingHTLCIndex[outputIndex]
sigHash = func() ([]byte, error) {
op := wire.OutPoint{
Hash: txHash,
Index: uint32(htlc.localOutputIndex),
}
htlcFee := htlcSuccessFee(feePerKw)
outputAmt := htlc.Amount.ToSatoshis() - htlcFee
successTx, err := createHtlcSuccessTx(op,
outputAmt, uint32(localChanCfg.CsvDelay),
keyRing.revocationKey, keyRing.delayKey)
if err != nil {
return nil, err
}
hashCache := txscript.NewTxSigHashes(successTx)
sigHash, err := txscript.CalcWitnessSigHash(
htlc.ourWitnessScript, hashCache,
txscript.SigHashAll, successTx, 0,
int64(htlc.Amount.ToSatoshis()),
)
if err != nil {
return nil, err
}
return sigHash, nil
}
// With the sighash generated, we'll also store the
// signature so it can be written to disk if this state
// is valid.
htlc.sig = htlcSigs[i]
// Otherwise, if this is an outgoing HTLC, then we'll need to
// generate a timeout transaction so we can verify the
// signature presented.
case localCommitmentView.outgoignHTLCIndex[outputIndex] != nil:
htlc := localCommitmentView.outgoignHTLCIndex[outputIndex]
sigHash = func() ([]byte, error) {
op := wire.OutPoint{
Hash: txHash,
Index: uint32(htlc.localOutputIndex),
}
htlcFee := htlcTimeoutFee(feePerKw)
outputAmt := htlc.Amount.ToSatoshis() - htlcFee
timeoutTx, err := createHtlcTimeoutTx(op,
outputAmt, htlc.Timeout,
uint32(localChanCfg.CsvDelay),
keyRing.revocationKey, keyRing.delayKey,
)
if err != nil {
return nil, err
}
hashCache := txscript.NewTxSigHashes(timeoutTx)
sigHash, err := txscript.CalcWitnessSigHash(
htlc.ourWitnessScript, hashCache,
txscript.SigHashAll, timeoutTx, 0,
int64(htlc.Amount.ToSatoshis()),
)
if err != nil {
return nil, err
}
return sigHash, nil
}
// With the sighash generated, we'll also store the
// signature so it can be written to disk if this state
// is valid.
htlc.sig = htlcSigs[i]
default:
continue
}
verifyJobs = append(verifyJobs, verifyJob{
pubKey: keyRing.remoteKey,
sig: htlcSigs[i],
sigHash: sigHash,
})
i++
}
return verifyJobs
}
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// ReceiveNewCommitment process a signature for a new commitment state sent by
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// the remote party. This method will should be called in response to the
// remote party initiating a new change, or when the remote party sends a
// signature fully accepting a new state we've initiated. If we are able to
// successfully validate the signature, then the generated commitment is added
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// to our local commitment chain. Once we send a revocation for our prior
// state, then this newly added commitment becomes our current accepted channel
// state.
func (lc *LightningChannel) ReceiveNewCommitment(commitSig *btcec.Signature,
htlcSigs []*btcec.Signature) error {
lc.Lock()
defer lc.Unlock()
lnwallet: update state machine to the version within the spec This commit updates the internal channel state machine to the one as described within the spec and currently implemented within the rest of the other Lightning implementations. At a high level the following modifications have been made: * When signing we no loner include the index of the remote party’s log that our signature covers. Instead we include ALL of our current updates, but only the updates of the remote party that we’ve ACK’d. * A pending change is considered ACK’d once a revocation message has been received, locking in the changes in the remote party’s commitment transaction. * When sending a new commitment, we remember the index of our log at that point so we can mark that portion of the log as ACK’d once we receive a revocation message from the remote party. * When receiving a new commitment signature, we include ALL of the remote party’s changes that we’ve received but only our set of changes that’ve been ACK’d by the remote party. * Implicitly a revocation message now also implicitly serves to ACK all the changes that were included in the CommitSig message received before it. The resulting change is a rather minor diff. However, with this state machine it’s important to note that the order to sig/revoke messages has been swapped. A proper exchange now looks like the following: * Alice -> Add, Add, Add * Alice -> Sig * Revoke <- Bob * Sig <- Bob * Alice -> Revoke One other thing that’s worth noting is that with this state machine, since what’s included in an update is implicit, both side may need to at times send a new commitment update in the case of a concurrent state transition initiated by both sides. Finally, all counters/indexes have been made 64-bit integers in order to properly match the spec.
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// Ensure that this new local update from the remote node respects all
// the constraints we specified during initial channel setup. If not,
// then we'll abort the channel as they've violated our constraints.
err := lc.validateCommitmentSanity(lc.remoteUpdateLog.logIndex,
lc.localUpdateLog.ackedIndex, false, true, true)
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if err != nil {
return err
}
// We're receiving a new commitment which attempts to extend our local
// commitment chain height by one, so fetch the proper commitment point
// as this well be needed to derive the keys required to construct the
// commitment.
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nextHeight := lc.currentHeight + 1
commitSecret, err := lc.channelState.RevocationProducer.AtIndex(nextHeight)
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if err != nil {
return err
}
commitPoint := ComputeCommitmentPoint(commitSecret[:])
keyRing := deriveCommitmentKeys(commitPoint, true, lc.localChanCfg,
lc.remoteChanCfg)
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// With the current commitment point re-calculated, construct the new
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// commitment view which includes all the entries we know of in their
// HTLC log, and up to ourLogIndex in our HTLC log.
lnwallet: update state machine to the version within the spec This commit updates the internal channel state machine to the one as described within the spec and currently implemented within the rest of the other Lightning implementations. At a high level the following modifications have been made: * When signing we no loner include the index of the remote party’s log that our signature covers. Instead we include ALL of our current updates, but only the updates of the remote party that we’ve ACK’d. * A pending change is considered ACK’d once a revocation message has been received, locking in the changes in the remote party’s commitment transaction. * When sending a new commitment, we remember the index of our log at that point so we can mark that portion of the log as ACK’d once we receive a revocation message from the remote party. * When receiving a new commitment signature, we include ALL of the remote party’s changes that we’ve received but only our set of changes that’ve been ACK’d by the remote party. * Implicitly a revocation message now also implicitly serves to ACK all the changes that were included in the CommitSig message received before it. The resulting change is a rather minor diff. However, with this state machine it’s important to note that the order to sig/revoke messages has been swapped. A proper exchange now looks like the following: * Alice -> Add, Add, Add * Alice -> Sig * Revoke <- Bob * Sig <- Bob * Alice -> Revoke One other thing that’s worth noting is that with this state machine, since what’s included in an update is implicit, both side may need to at times send a new commitment update in the case of a concurrent state transition initiated by both sides. Finally, all counters/indexes have been made 64-bit integers in order to properly match the spec.
2017-02-21 04:55:33 +03:00
localCommitmentView, err := lc.fetchCommitmentView(false,
lc.localUpdateLog.ackedIndex, lc.remoteUpdateLog.logIndex, keyRing)
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if err != nil {
return err
}
walletLog.Tracef("ChannelPoint(%v): extending local chain to height %v",
lc.channelState.FundingOutpoint, localCommitmentView.height)
lnwallet: update state machine to the version within the spec This commit updates the internal channel state machine to the one as described within the spec and currently implemented within the rest of the other Lightning implementations. At a high level the following modifications have been made: * When signing we no loner include the index of the remote party’s log that our signature covers. Instead we include ALL of our current updates, but only the updates of the remote party that we’ve ACK’d. * A pending change is considered ACK’d once a revocation message has been received, locking in the changes in the remote party’s commitment transaction. * When sending a new commitment, we remember the index of our log at that point so we can mark that portion of the log as ACK’d once we receive a revocation message from the remote party. * When receiving a new commitment signature, we include ALL of the remote party’s changes that we’ve received but only our set of changes that’ve been ACK’d by the remote party. * Implicitly a revocation message now also implicitly serves to ACK all the changes that were included in the CommitSig message received before it. The resulting change is a rather minor diff. However, with this state machine it’s important to note that the order to sig/revoke messages has been swapped. A proper exchange now looks like the following: * Alice -> Add, Add, Add * Alice -> Sig * Revoke <- Bob * Sig <- Bob * Alice -> Revoke One other thing that’s worth noting is that with this state machine, since what’s included in an update is implicit, both side may need to at times send a new commitment update in the case of a concurrent state transition initiated by both sides. Finally, all counters/indexes have been made 64-bit integers in order to properly match the spec.
2017-02-21 04:55:33 +03:00
walletLog.Tracef("ChannelPoint(%v): local chain: our_balance=%v, "+
"their_balance=%v, commit_tx: %v", lc.channelState.FundingOutpoint,
localCommitmentView.ourBalance, localCommitmentView.theirBalance,
newLogClosure(func() string {
return spew.Sdump(localCommitmentView.txn)
lnwallet: update state machine to the version within the spec This commit updates the internal channel state machine to the one as described within the spec and currently implemented within the rest of the other Lightning implementations. At a high level the following modifications have been made: * When signing we no loner include the index of the remote party’s log that our signature covers. Instead we include ALL of our current updates, but only the updates of the remote party that we’ve ACK’d. * A pending change is considered ACK’d once a revocation message has been received, locking in the changes in the remote party’s commitment transaction. * When sending a new commitment, we remember the index of our log at that point so we can mark that portion of the log as ACK’d once we receive a revocation message from the remote party. * When receiving a new commitment signature, we include ALL of the remote party’s changes that we’ve received but only our set of changes that’ve been ACK’d by the remote party. * Implicitly a revocation message now also implicitly serves to ACK all the changes that were included in the CommitSig message received before it. The resulting change is a rather minor diff. However, with this state machine it’s important to note that the order to sig/revoke messages has been swapped. A proper exchange now looks like the following: * Alice -> Add, Add, Add * Alice -> Sig * Revoke <- Bob * Sig <- Bob * Alice -> Revoke One other thing that’s worth noting is that with this state machine, since what’s included in an update is implicit, both side may need to at times send a new commitment update in the case of a concurrent state transition initiated by both sides. Finally, all counters/indexes have been made 64-bit integers in order to properly match the spec.
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}),
)
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// Construct the sighash of the commitment transaction corresponding to
// this newly proposed state update.
localCommitTx := localCommitmentView.txn
multiSigScript := lc.FundingWitnessScript
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hashCache := txscript.NewTxSigHashes(localCommitTx)
sigHash, err := txscript.CalcWitnessSigHash(multiSigScript, hashCache,
txscript.SigHashAll, localCommitTx, 0,
int64(lc.channelState.Capacity))
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if err != nil {
// TODO(roasbeef): fetchview has already mutated the HTLCs...
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// * need to either roll-back, or make pure
return err
}
// As an optimization, we'll generate a series of jobs for the worker
// pool to verify each of the HTLc signatures presented. Once
// generated, we'll submit these jobs to the worker pool.
verifyJobs := genHtlcSigValidationJobs(localCommitmentView,
keyRing, htlcSigs, lc.localChanCfg, lc.remoteChanCfg)
cancelChan := make(chan struct{})
verifyResps := lc.sigPool.SubmitVerifyBatch(verifyJobs, cancelChan)
// While the HTLC verification jobs are proceeding asynchronously,
// we'll ensure that the newly constructed commitment state has a valid
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// signature.
verifyKey := btcec.PublicKey{
X: lc.remoteChanCfg.MultiSigKey.X,
Y: lc.remoteChanCfg.MultiSigKey.Y,
Curve: btcec.S256(),
}
if !commitSig.Verify(sigHash, &verifyKey) {
close(cancelChan)
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return fmt.Errorf("invalid commitment signature")
}
// With the primary commitment transaction validated, we'll check each
// of the HTLC validation jobs.
for i := 0; i < len(verifyJobs); i++ {
// In the case that a single signature is invalid, we'll exit
// early and cancel all the outstanding verification jobs.
if err := <-verifyResps; err != nil {
close(cancelChan)
return fmt.Errorf("invalid htlc signature: %v", err)
}
}
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// The signature checks out, so we can now add the new commitment to
// our local commitment chain.
localCommitmentView.sig = commitSig.Serialize()
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lc.localCommitChain.addCommitment(localCommitmentView)
// If we are not channel initiator, then the commitment just received
// would've signed any received fee update since last commitment. Mark
// any such fee update as pending ACK (so we remember to ACK it on our
// next commitment), and set pendingFeeUpdate to nil. We can do this
// since we won't receive any new commitment before ACKing.
if !lc.channelState.IsInitiator {
lc.pendingAckFeeUpdate = lc.pendingFeeUpdate
lc.pendingFeeUpdate = nil
}
lnwallet: update state machine to the version within the spec This commit updates the internal channel state machine to the one as described within the spec and currently implemented within the rest of the other Lightning implementations. At a high level the following modifications have been made: * When signing we no loner include the index of the remote party’s log that our signature covers. Instead we include ALL of our current updates, but only the updates of the remote party that we’ve ACK’d. * A pending change is considered ACK’d once a revocation message has been received, locking in the changes in the remote party’s commitment transaction. * When sending a new commitment, we remember the index of our log at that point so we can mark that portion of the log as ACK’d once we receive a revocation message from the remote party. * When receiving a new commitment signature, we include ALL of the remote party’s changes that we’ve received but only our set of changes that’ve been ACK’d by the remote party. * Implicitly a revocation message now also implicitly serves to ACK all the changes that were included in the CommitSig message received before it. The resulting change is a rather minor diff. However, with this state machine it’s important to note that the order to sig/revoke messages has been swapped. A proper exchange now looks like the following: * Alice -> Add, Add, Add * Alice -> Sig * Revoke <- Bob * Sig <- Bob * Alice -> Revoke One other thing that’s worth noting is that with this state machine, since what’s included in an update is implicit, both side may need to at times send a new commitment update in the case of a concurrent state transition initiated by both sides. Finally, all counters/indexes have been made 64-bit integers in order to properly match the spec.
2017-02-21 04:55:33 +03:00
// Finally we'll keep track of the current pending index for the remote
// party so we can ACK up to this value once we revoke our current
// commitment.
lc.remoteUpdateLog.initiateTransition()
return nil
}
// FullySynced returns a boolean value reflecting if both commitment chains
// (remote+local) are fully in sync. Both commitment chains are fully in sync
// if the tip of each chain includes the latest committed changes from both
// sides.
func (lc *LightningChannel) FullySynced() bool {
lc.RLock()
defer lc.RUnlock()
oweCommitment := (lc.localCommitChain.tip().height >
lc.remoteCommitChain.tip().height)
lnwallet: update state machine to the version within the spec This commit updates the internal channel state machine to the one as described within the spec and currently implemented within the rest of the other Lightning implementations. At a high level the following modifications have been made: * When signing we no loner include the index of the remote party’s log that our signature covers. Instead we include ALL of our current updates, but only the updates of the remote party that we’ve ACK’d. * A pending change is considered ACK’d once a revocation message has been received, locking in the changes in the remote party’s commitment transaction. * When sending a new commitment, we remember the index of our log at that point so we can mark that portion of the log as ACK’d once we receive a revocation message from the remote party. * When receiving a new commitment signature, we include ALL of the remote party’s changes that we’ve received but only our set of changes that’ve been ACK’d by the remote party. * Implicitly a revocation message now also implicitly serves to ACK all the changes that were included in the CommitSig message received before it. The resulting change is a rather minor diff. However, with this state machine it’s important to note that the order to sig/revoke messages has been swapped. A proper exchange now looks like the following: * Alice -> Add, Add, Add * Alice -> Sig * Revoke <- Bob * Sig <- Bob * Alice -> Revoke One other thing that’s worth noting is that with this state machine, since what’s included in an update is implicit, both side may need to at times send a new commitment update in the case of a concurrent state transition initiated by both sides. Finally, all counters/indexes have been made 64-bit integers in order to properly match the spec.
2017-02-21 04:55:33 +03:00
localUpdatesSynced := (lc.localCommitChain.tip().ourMessageIndex ==
lc.remoteCommitChain.tip().ourMessageIndex)
remoteUpdatesSynced := (lc.localCommitChain.tip().theirMessageIndex ==
lc.remoteCommitChain.tip().theirMessageIndex)
return !oweCommitment && localUpdatesSynced && remoteUpdatesSynced
}
2016-07-06 03:01:55 +03:00
// RevokeCurrentCommitment revokes the next lowest unrevoked commitment
// transaction in the local commitment chain. As a result the edge of our
// revocation window is extended by one, and the tail of our local commitment
// chain is advanced by a single commitment. This now lowest unrevoked
// commitment becomes our currently accepted state within the channel.
lnwallet: update state machine to the version within the spec This commit updates the internal channel state machine to the one as described within the spec and currently implemented within the rest of the other Lightning implementations. At a high level the following modifications have been made: * When signing we no loner include the index of the remote party’s log that our signature covers. Instead we include ALL of our current updates, but only the updates of the remote party that we’ve ACK’d. * A pending change is considered ACK’d once a revocation message has been received, locking in the changes in the remote party’s commitment transaction. * When sending a new commitment, we remember the index of our log at that point so we can mark that portion of the log as ACK’d once we receive a revocation message from the remote party. * When receiving a new commitment signature, we include ALL of the remote party’s changes that we’ve received but only our set of changes that’ve been ACK’d by the remote party. * Implicitly a revocation message now also implicitly serves to ACK all the changes that were included in the CommitSig message received before it. The resulting change is a rather minor diff. However, with this state machine it’s important to note that the order to sig/revoke messages has been swapped. A proper exchange now looks like the following: * Alice -> Add, Add, Add * Alice -> Sig * Revoke <- Bob * Sig <- Bob * Alice -> Revoke One other thing that’s worth noting is that with this state machine, since what’s included in an update is implicit, both side may need to at times send a new commitment update in the case of a concurrent state transition initiated by both sides. Finally, all counters/indexes have been made 64-bit integers in order to properly match the spec.
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func (lc *LightningChannel) RevokeCurrentCommitment() (*lnwire.RevokeAndAck, error) {
lc.Lock()
defer lc.Unlock()
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// Now that we've accept a new state transition, we send the remote
// party the revocation for our current commitment state.
lnwallet: update state machine to the version within the spec This commit updates the internal channel state machine to the one as described within the spec and currently implemented within the rest of the other Lightning implementations. At a high level the following modifications have been made: * When signing we no loner include the index of the remote party’s log that our signature covers. Instead we include ALL of our current updates, but only the updates of the remote party that we’ve ACK’d. * A pending change is considered ACK’d once a revocation message has been received, locking in the changes in the remote party’s commitment transaction. * When sending a new commitment, we remember the index of our log at that point so we can mark that portion of the log as ACK’d once we receive a revocation message from the remote party. * When receiving a new commitment signature, we include ALL of the remote party’s changes that we’ve received but only our set of changes that’ve been ACK’d by the remote party. * Implicitly a revocation message now also implicitly serves to ACK all the changes that were included in the CommitSig message received before it. The resulting change is a rather minor diff. However, with this state machine it’s important to note that the order to sig/revoke messages has been swapped. A proper exchange now looks like the following: * Alice -> Add, Add, Add * Alice -> Sig * Revoke <- Bob * Sig <- Bob * Alice -> Revoke One other thing that’s worth noting is that with this state machine, since what’s included in an update is implicit, both side may need to at times send a new commitment update in the case of a concurrent state transition initiated by both sides. Finally, all counters/indexes have been made 64-bit integers in order to properly match the spec.
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revocationMsg := &lnwire.RevokeAndAck{}
commitSecret, err := lc.channelState.RevocationProducer.AtIndex(
lc.currentHeight,
)
if err != nil {
return nil, err
}
copy(revocationMsg.Revocation[:], commitSecret[:])
// Along with this revocation, we'll also send the _next_ commitment
// point that the remote party should use to create our next commitment
// transaction. We use a +2 here as we already gave them a look ahead
// of size one after the FundingLocked message was sent:
//
// 0: current revocation, 1: their "next" revocation, 2: this revocation
//
// We're revoking the current revocation. Once they receive this
// message they'll set the "current" revocation for us to their stored
// "next" revocation, and this revocation will become their new "next"
// revocation.
//
// Put simply in the window slides to the left by one.
nextCommitSecret, err := lc.channelState.RevocationProducer.AtIndex(
lc.currentHeight + 2,
)
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if err != nil {
return nil, err
}
revocationMsg.NextRevocationKey = ComputeCommitmentPoint(
nextCommitSecret[:],
)
walletLog.Tracef("ChannelPoint(%v): revoking height=%v, now at height=%v",
lc.channelState.FundingOutpoint, lc.localCommitChain.tail().height,
lc.currentHeight+1)
2016-07-06 03:01:55 +03:00
// Advance our tail, as we've revoked our previous state.
lc.localCommitChain.advanceTail()
lc.currentHeight++
// Additionally, generate a channel delta for this state transition for
// persistent storage.
2016-07-06 03:01:55 +03:00
tail := lc.localCommitChain.tail()
lnwallet: fix bug that retrieves incorrect pkScript in toChannelDelta() Description of bug: When calling ReceiveNewCommitment() we will progress through methods fetchCommitmentView and addHTLC which will add HTLC outputs to the commitment transaction in the local commitment chain and save the pkScript to the relevant PaymentDescriptor which resides in the corresponding updateLog. Finally the local commitment will be added to the local commitment chain. When the same user next calls SignNextCommitment we will again progress through fetchCommitmentView and addHTLC. In addHTLC we will now overwrite the pkScripts in the PaymentDescriptors with the pkScript from the context of the remote commitment. When we later call RevokeCurrentCommitment and proceed into toChannelDelta, we will not be able to find the correct pkScript in the PaymentDescriptor to match it against the outputs in the commitment transaction. This will lead to the nested function locateOutputIndex returning incorrect values. Fixing the bug: We introduce three new fields in PaymentDescriptor: * ourPkScript * theirPkScript * theirPrevPkScript ourPkScript will include the pkScript for the HTLC from the context of the local commitment. theirPkScript will take the value of the latest pkScript for the HTLC from the context of the remote commitment. theirPrevPkScript will take the second-latest pkScript for the HTLC from the context of the remote commitment. This is the value we use in toChannelDelta when we save a revoked commitment from our peer. The appropriate value of these fields are set in the addHTLC method. Additionally we pass a boolean value to toChannelDelta so we know whether we are operating on a local or remote commitment and grab the correct pkScript in locateUpdateIndex.
2017-01-20 14:37:30 +03:00
delta, err := tail.toChannelDelta(true)
if err != nil {
return nil, err
}
err = lc.channelState.UpdateCommitment(tail.txn, tail.sig, delta)
if err != nil {
return nil, err
}
2016-07-06 03:01:55 +03:00
walletLog.Tracef("ChannelPoint(%v): state transition accepted: "+
"our_balance=%v, their_balance=%v",
lc.channelState.FundingOutpoint, tail.ourBalance,
tail.theirBalance)
lnwallet: update state machine to the version within the spec This commit updates the internal channel state machine to the one as described within the spec and currently implemented within the rest of the other Lightning implementations. At a high level the following modifications have been made: * When signing we no loner include the index of the remote party’s log that our signature covers. Instead we include ALL of our current updates, but only the updates of the remote party that we’ve ACK’d. * A pending change is considered ACK’d once a revocation message has been received, locking in the changes in the remote party’s commitment transaction. * When sending a new commitment, we remember the index of our log at that point so we can mark that portion of the log as ACK’d once we receive a revocation message from the remote party. * When receiving a new commitment signature, we include ALL of the remote party’s changes that we’ve received but only our set of changes that’ve been ACK’d by the remote party. * Implicitly a revocation message now also implicitly serves to ACK all the changes that were included in the CommitSig message received before it. The resulting change is a rather minor diff. However, with this state machine it’s important to note that the order to sig/revoke messages has been swapped. A proper exchange now looks like the following: * Alice -> Add, Add, Add * Alice -> Sig * Revoke <- Bob * Sig <- Bob * Alice -> Revoke One other thing that’s worth noting is that with this state machine, since what’s included in an update is implicit, both side may need to at times send a new commitment update in the case of a concurrent state transition initiated by both sides. Finally, all counters/indexes have been made 64-bit integers in order to properly match the spec.
2017-02-21 04:55:33 +03:00
// In the process of revoking our current commitment, we've also
// implicitly ACK'd their set of pending changes that arrived before
// the signature the triggered this revocation. So we'll move up their
// ACK'd index within the log to right at this set of pending changes.
lc.remoteUpdateLog.ackTransition()
revocationMsg.ChanID = lnwire.NewChanIDFromOutPoint(
&lc.channelState.FundingOutpoint,
)
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return revocationMsg, nil
}
// ReceiveRevocation processes a revocation sent by the remote party for the
// lowest unrevoked commitment within their commitment chain. We receive a
// revocation either during the initial session negotiation wherein revocation
// windows are extended, or in response to a state update that we initiate. If
// successful, then the remote commitment chain is advanced by a single
// commitment, and a log compaction is attempted. In addition, a slice of
lnwallet: update state machine to the version within the spec This commit updates the internal channel state machine to the one as described within the spec and currently implemented within the rest of the other Lightning implementations. At a high level the following modifications have been made: * When signing we no loner include the index of the remote party’s log that our signature covers. Instead we include ALL of our current updates, but only the updates of the remote party that we’ve ACK’d. * A pending change is considered ACK’d once a revocation message has been received, locking in the changes in the remote party’s commitment transaction. * When sending a new commitment, we remember the index of our log at that point so we can mark that portion of the log as ACK’d once we receive a revocation message from the remote party. * When receiving a new commitment signature, we include ALL of the remote party’s changes that we’ve received but only our set of changes that’ve been ACK’d by the remote party. * Implicitly a revocation message now also implicitly serves to ACK all the changes that were included in the CommitSig message received before it. The resulting change is a rather minor diff. However, with this state machine it’s important to note that the order to sig/revoke messages has been swapped. A proper exchange now looks like the following: * Alice -> Add, Add, Add * Alice -> Sig * Revoke <- Bob * Sig <- Bob * Alice -> Revoke One other thing that’s worth noting is that with this state machine, since what’s included in an update is implicit, both side may need to at times send a new commitment update in the case of a concurrent state transition initiated by both sides. Finally, all counters/indexes have been made 64-bit integers in order to properly match the spec.
2017-02-21 04:55:33 +03:00
// HTLC's which can be forwarded upstream are returned.
func (lc *LightningChannel) ReceiveRevocation(revMsg *lnwire.RevokeAndAck) ([]*PaymentDescriptor, error) {
lc.Lock()
defer lc.Unlock()
lnwallet: update state machine to the version within the spec This commit updates the internal channel state machine to the one as described within the spec and currently implemented within the rest of the other Lightning implementations. At a high level the following modifications have been made: * When signing we no loner include the index of the remote party’s log that our signature covers. Instead we include ALL of our current updates, but only the updates of the remote party that we’ve ACK’d. * A pending change is considered ACK’d once a revocation message has been received, locking in the changes in the remote party’s commitment transaction. * When sending a new commitment, we remember the index of our log at that point so we can mark that portion of the log as ACK’d once we receive a revocation message from the remote party. * When receiving a new commitment signature, we include ALL of the remote party’s changes that we’ve received but only our set of changes that’ve been ACK’d by the remote party. * Implicitly a revocation message now also implicitly serves to ACK all the changes that were included in the CommitSig message received before it. The resulting change is a rather minor diff. However, with this state machine it’s important to note that the order to sig/revoke messages has been swapped. A proper exchange now looks like the following: * Alice -> Add, Add, Add * Alice -> Sig * Revoke <- Bob * Sig <- Bob * Alice -> Revoke One other thing that’s worth noting is that with this state machine, since what’s included in an update is implicit, both side may need to at times send a new commitment update in the case of a concurrent state transition initiated by both sides. Finally, all counters/indexes have been made 64-bit integers in order to properly match the spec.
2017-02-21 04:55:33 +03:00
// Now that we've received a new revocation from the remote party,
// we'll toggle our pendingACk bool to indicate that we can create a
// new commitment state after we finish processing this revocation.
lc.pendingACK = false
// Ensure that the new pre-image can be placed in preimage store.
store := lc.channelState.RevocationStore
revocation, err := chainhash.NewHash(revMsg.Revocation[:])
if err != nil {
return nil, err
}
if err := store.AddNextEntry(revocation); err != nil {
return nil, err
2016-07-06 03:01:55 +03:00
}
// Verify that if we use the commitment point computed based off of the
// revealed secret to derive a revocation key with our revocation base
// point, then it matches the current revocation of the remote party.
currentCommitPoint := lc.channelState.RemoteCurrentRevocation
derivedCommitPoint := ComputeCommitmentPoint(revMsg.Revocation[:])
if !derivedCommitPoint.IsEqual(currentCommitPoint) {
return nil, fmt.Errorf("revocation key mismatch")
2016-07-06 03:01:55 +03:00
}
// Now that we've verified that the prior commitment has been properly
// revoked, we'll advance the revocation state we track for the remote
// party: the new current revocation is what was previously the next
// revocation, and the new next revocation is set to the key included
// in the message.
lc.channelState.RemoteCurrentRevocation = lc.channelState.RemoteNextRevocation
lc.channelState.RemoteNextRevocation = revMsg.NextRevocationKey
2016-07-06 03:01:55 +03:00
walletLog.Tracef("ChannelPoint(%v): remote party accepted state transition, "+
"revoked height %v, now at %v", lc.channelState.FundingOutpoint,
lc.remoteCommitChain.tail().height,
lc.remoteCommitChain.tail().height+1)
// At this point, the revocation has been accepted, and we've rotated
// the current revocation key+hash for the remote party. Therefore we
// sync now to ensure the revocation producer state is consistent with
// the current commitment height.
tail := lc.remoteCommitChain.tail()
lnwallet: fix bug that retrieves incorrect pkScript in toChannelDelta() Description of bug: When calling ReceiveNewCommitment() we will progress through methods fetchCommitmentView and addHTLC which will add HTLC outputs to the commitment transaction in the local commitment chain and save the pkScript to the relevant PaymentDescriptor which resides in the corresponding updateLog. Finally the local commitment will be added to the local commitment chain. When the same user next calls SignNextCommitment we will again progress through fetchCommitmentView and addHTLC. In addHTLC we will now overwrite the pkScripts in the PaymentDescriptors with the pkScript from the context of the remote commitment. When we later call RevokeCurrentCommitment and proceed into toChannelDelta, we will not be able to find the correct pkScript in the PaymentDescriptor to match it against the outputs in the commitment transaction. This will lead to the nested function locateOutputIndex returning incorrect values. Fixing the bug: We introduce three new fields in PaymentDescriptor: * ourPkScript * theirPkScript * theirPrevPkScript ourPkScript will include the pkScript for the HTLC from the context of the local commitment. theirPkScript will take the value of the latest pkScript for the HTLC from the context of the remote commitment. theirPrevPkScript will take the second-latest pkScript for the HTLC from the context of the remote commitment. This is the value we use in toChannelDelta when we save a revoked commitment from our peer. The appropriate value of these fields are set in the addHTLC method. Additionally we pass a boolean value to toChannelDelta so we know whether we are operating on a local or remote commitment and grab the correct pkScript in locateUpdateIndex.
2017-01-20 14:37:30 +03:00
delta, err := tail.toChannelDelta(false)
if err != nil {
return nil, err
}
if err := lc.channelState.AppendToRevocationLog(delta); err != nil {
return nil, err
}
2016-07-06 03:01:55 +03:00
// Since they revoked the current lowest height in their commitment
// chain, we can advance their chain by a single commitment.
lc.remoteCommitChain.advanceTail()
remoteChainTail := lc.remoteCommitChain.tail().height
localChainTail := lc.localCommitChain.tail().height
// 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.
var htlcsToForward []*PaymentDescriptor
lnwallet: update state machine to the version within the spec This commit updates the internal channel state machine to the one as described within the spec and currently implemented within the rest of the other Lightning implementations. At a high level the following modifications have been made: * When signing we no loner include the index of the remote party’s log that our signature covers. Instead we include ALL of our current updates, but only the updates of the remote party that we’ve ACK’d. * A pending change is considered ACK’d once a revocation message has been received, locking in the changes in the remote party’s commitment transaction. * When sending a new commitment, we remember the index of our log at that point so we can mark that portion of the log as ACK’d once we receive a revocation message from the remote party. * When receiving a new commitment signature, we include ALL of the remote party’s changes that we’ve received but only our set of changes that’ve been ACK’d by the remote party. * Implicitly a revocation message now also implicitly serves to ACK all the changes that were included in the CommitSig message received before it. The resulting change is a rather minor diff. However, with this state machine it’s important to note that the order to sig/revoke messages has been swapped. A proper exchange now looks like the following: * Alice -> Add, Add, Add * Alice -> Sig * Revoke <- Bob * Sig <- Bob * Alice -> Revoke One other thing that’s worth noting is that with this state machine, since what’s included in an update is implicit, both side may need to at times send a new commitment update in the case of a concurrent state transition initiated by both sides. Finally, all counters/indexes have been made 64-bit integers in order to properly match the spec.
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for e := lc.remoteUpdateLog.Front(); e != nil; e = e.Next() {
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htlc := e.Value.(*PaymentDescriptor)
if htlc.isForwarded {
continue
}
// TODO(roasbeef): re-visit after adding persistence to HTLCs
// * either record add height, or set to N - 1
uncomitted := (htlc.addCommitHeightRemote == 0 ||
htlc.addCommitHeightLocal == 0)
if htlc.EntryType == Add && uncomitted {
continue
}
if htlc.EntryType == Add &&
remoteChainTail >= htlc.addCommitHeightRemote &&
localChainTail >= htlc.addCommitHeightLocal {
lnwallet: update state machine to the version within the spec This commit updates the internal channel state machine to the one as described within the spec and currently implemented within the rest of the other Lightning implementations. At a high level the following modifications have been made: * When signing we no loner include the index of the remote party’s log that our signature covers. Instead we include ALL of our current updates, but only the updates of the remote party that we’ve ACK’d. * A pending change is considered ACK’d once a revocation message has been received, locking in the changes in the remote party’s commitment transaction. * When sending a new commitment, we remember the index of our log at that point so we can mark that portion of the log as ACK’d once we receive a revocation message from the remote party. * When receiving a new commitment signature, we include ALL of the remote party’s changes that we’ve received but only our set of changes that’ve been ACK’d by the remote party. * Implicitly a revocation message now also implicitly serves to ACK all the changes that were included in the CommitSig message received before it. The resulting change is a rather minor diff. However, with this state machine it’s important to note that the order to sig/revoke messages has been swapped. A proper exchange now looks like the following: * Alice -> Add, Add, Add * Alice -> Sig * Revoke <- Bob * Sig <- Bob * Alice -> Revoke One other thing that’s worth noting is that with this state machine, since what’s included in an update is implicit, both side may need to at times send a new commitment update in the case of a concurrent state transition initiated by both sides. Finally, all counters/indexes have been made 64-bit integers in order to properly match the spec.
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htlc.isForwarded = true
htlcsToForward = append(htlcsToForward, htlc)
} else if htlc.EntryType != Add &&
remoteChainTail >= htlc.removeCommitHeightRemote &&
localChainTail >= htlc.removeCommitHeightLocal {
lnwallet: update state machine to the version within the spec This commit updates the internal channel state machine to the one as described within the spec and currently implemented within the rest of the other Lightning implementations. At a high level the following modifications have been made: * When signing we no loner include the index of the remote party’s log that our signature covers. Instead we include ALL of our current updates, but only the updates of the remote party that we’ve ACK’d. * A pending change is considered ACK’d once a revocation message has been received, locking in the changes in the remote party’s commitment transaction. * When sending a new commitment, we remember the index of our log at that point so we can mark that portion of the log as ACK’d once we receive a revocation message from the remote party. * When receiving a new commitment signature, we include ALL of the remote party’s changes that we’ve received but only our set of changes that’ve been ACK’d by the remote party. * Implicitly a revocation message now also implicitly serves to ACK all the changes that were included in the CommitSig message received before it. The resulting change is a rather minor diff. However, with this state machine it’s important to note that the order to sig/revoke messages has been swapped. A proper exchange now looks like the following: * Alice -> Add, Add, Add * Alice -> Sig * Revoke <- Bob * Sig <- Bob * Alice -> Revoke One other thing that’s worth noting is that with this state machine, since what’s included in an update is implicit, both side may need to at times send a new commitment update in the case of a concurrent state transition initiated by both sides. Finally, all counters/indexes have been made 64-bit integers in order to properly match the spec.
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htlc.isForwarded = true
htlcsToForward = append(htlcsToForward, htlc)
}
}
// As we've just completed a new state transition, attempt to see if we
// can remove any entries from the update log which have been removed
// from the PoV of both commitment chains.
compactLogs(lc.localUpdateLog, lc.remoteUpdateLog,
localChainTail, remoteChainTail)
// As a final step, now that we've received an ACK for our last batch
// of pending changes, we'll update our local ACK'd index to the now
// commitment index, and reset our pendingACKIndex.
lnwallet: update state machine to the version within the spec This commit updates the internal channel state machine to the one as described within the spec and currently implemented within the rest of the other Lightning implementations. At a high level the following modifications have been made: * When signing we no loner include the index of the remote party’s log that our signature covers. Instead we include ALL of our current updates, but only the updates of the remote party that we’ve ACK’d. * A pending change is considered ACK’d once a revocation message has been received, locking in the changes in the remote party’s commitment transaction. * When sending a new commitment, we remember the index of our log at that point so we can mark that portion of the log as ACK’d once we receive a revocation message from the remote party. * When receiving a new commitment signature, we include ALL of the remote party’s changes that we’ve received but only our set of changes that’ve been ACK’d by the remote party. * Implicitly a revocation message now also implicitly serves to ACK all the changes that were included in the CommitSig message received before it. The resulting change is a rather minor diff. However, with this state machine it’s important to note that the order to sig/revoke messages has been swapped. A proper exchange now looks like the following: * Alice -> Add, Add, Add * Alice -> Sig * Revoke <- Bob * Sig <- Bob * Alice -> Revoke One other thing that’s worth noting is that with this state machine, since what’s included in an update is implicit, both side may need to at times send a new commitment update in the case of a concurrent state transition initiated by both sides. Finally, all counters/indexes have been made 64-bit integers in order to properly match the spec.
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lc.localUpdateLog.ackTransition()
return htlcsToForward, nil
}
// NextRevocationKey returns the commitment point for the _next_ commitment
// height. The pubkey returned by this function is required by the remote party
// along with their revocation base to to extend our commitment chain with a
// new commitment.
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func (lc *LightningChannel) NextRevocationKey() (*btcec.PublicKey, error) {
lc.RLock()
defer lc.RUnlock()
nextHeight := lc.currentHeight + 1
revocation, err := lc.channelState.RevocationProducer.AtIndex(nextHeight)
if err != nil {
return nil, err
}
return ComputeCommitmentPoint(revocation[:]), nil
}
// InitNextRevocation inserts the passed commitment point as the _next_
// revocation to be used when created a new commitment state for the remote
// party. This function MUST be called before the channel can accept or propose
// any new states.
func (lc *LightningChannel) InitNextRevocation(revKey *btcec.PublicKey) error {
lc.Lock()
defer lc.Unlock()
return lc.channelState.InsertNextRevocation(revKey)
}
// AddHTLC adds an HTLC to the state machine's local update log. This method
// should be called when preparing to send an outgoing HTLC.
lnwallet: update state machine to the version within the spec This commit updates the internal channel state machine to the one as described within the spec and currently implemented within the rest of the other Lightning implementations. At a high level the following modifications have been made: * When signing we no loner include the index of the remote party’s log that our signature covers. Instead we include ALL of our current updates, but only the updates of the remote party that we’ve ACK’d. * A pending change is considered ACK’d once a revocation message has been received, locking in the changes in the remote party’s commitment transaction. * When sending a new commitment, we remember the index of our log at that point so we can mark that portion of the log as ACK’d once we receive a revocation message from the remote party. * When receiving a new commitment signature, we include ALL of the remote party’s changes that we’ve received but only our set of changes that’ve been ACK’d by the remote party. * Implicitly a revocation message now also implicitly serves to ACK all the changes that were included in the CommitSig message received before it. The resulting change is a rather minor diff. However, with this state machine it’s important to note that the order to sig/revoke messages has been swapped. A proper exchange now looks like the following: * Alice -> Add, Add, Add * Alice -> Sig * Revoke <- Bob * Sig <- Bob * Alice -> Revoke One other thing that’s worth noting is that with this state machine, since what’s included in an update is implicit, both side may need to at times send a new commitment update in the case of a concurrent state transition initiated by both sides. Finally, all counters/indexes have been made 64-bit integers in order to properly match the spec.
2017-02-21 04:55:33 +03:00
func (lc *LightningChannel) AddHTLC(htlc *lnwire.UpdateAddHTLC) (uint64, error) {
lc.Lock()
defer lc.Unlock()
lnwallet: update state machine to the version within the spec This commit updates the internal channel state machine to the one as described within the spec and currently implemented within the rest of the other Lightning implementations. At a high level the following modifications have been made: * When signing we no loner include the index of the remote party’s log that our signature covers. Instead we include ALL of our current updates, but only the updates of the remote party that we’ve ACK’d. * A pending change is considered ACK’d once a revocation message has been received, locking in the changes in the remote party’s commitment transaction. * When sending a new commitment, we remember the index of our log at that point so we can mark that portion of the log as ACK’d once we receive a revocation message from the remote party. * When receiving a new commitment signature, we include ALL of the remote party’s changes that we’ve received but only our set of changes that’ve been ACK’d by the remote party. * Implicitly a revocation message now also implicitly serves to ACK all the changes that were included in the CommitSig message received before it. The resulting change is a rather minor diff. However, with this state machine it’s important to note that the order to sig/revoke messages has been swapped. A proper exchange now looks like the following: * Alice -> Add, Add, Add * Alice -> Sig * Revoke <- Bob * Sig <- Bob * Alice -> Revoke One other thing that’s worth noting is that with this state machine, since what’s included in an update is implicit, both side may need to at times send a new commitment update in the case of a concurrent state transition initiated by both sides. Finally, all counters/indexes have been made 64-bit integers in order to properly match the spec.
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if err := lc.validateCommitmentSanity(lc.remoteUpdateLog.logIndex,
lc.localUpdateLog.logIndex, true, true, false); err != nil {
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return 0, err
}
if lc.availableLocalBalance < htlc.Amount {
return 0, ErrInsufficientBalance
}
lc.availableLocalBalance -= htlc.Amount
2016-07-06 03:01:55 +03:00
pd := &PaymentDescriptor{
EntryType: Add,
RHash: PaymentHash(htlc.PaymentHash),
Timeout: htlc.Expiry,
Amount: htlc.Amount,
LogIndex: lc.localUpdateLog.logIndex,
HtlcIndex: lc.localUpdateLog.htlcCounter,
}
lc.localUpdateLog.appendHtlc(pd)
return pd.HtlcIndex, nil
}
// ReceiveHTLC adds an HTLC to the state machine's remote update log. This
// method should be called in response to receiving a new HTLC from the remote
// party.
lnwallet: update state machine to the version within the spec This commit updates the internal channel state machine to the one as described within the spec and currently implemented within the rest of the other Lightning implementations. At a high level the following modifications have been made: * When signing we no loner include the index of the remote party’s log that our signature covers. Instead we include ALL of our current updates, but only the updates of the remote party that we’ve ACK’d. * A pending change is considered ACK’d once a revocation message has been received, locking in the changes in the remote party’s commitment transaction. * When sending a new commitment, we remember the index of our log at that point so we can mark that portion of the log as ACK’d once we receive a revocation message from the remote party. * When receiving a new commitment signature, we include ALL of the remote party’s changes that we’ve received but only our set of changes that’ve been ACK’d by the remote party. * Implicitly a revocation message now also implicitly serves to ACK all the changes that were included in the CommitSig message received before it. The resulting change is a rather minor diff. However, with this state machine it’s important to note that the order to sig/revoke messages has been swapped. A proper exchange now looks like the following: * Alice -> Add, Add, Add * Alice -> Sig * Revoke <- Bob * Sig <- Bob * Alice -> Revoke One other thing that’s worth noting is that with this state machine, since what’s included in an update is implicit, both side may need to at times send a new commitment update in the case of a concurrent state transition initiated by both sides. Finally, all counters/indexes have been made 64-bit integers in order to properly match the spec.
2017-02-21 04:55:33 +03:00
func (lc *LightningChannel) ReceiveHTLC(htlc *lnwire.UpdateAddHTLC) (uint64, error) {
lc.Lock()
defer lc.Unlock()
lnwallet: update state machine to the version within the spec This commit updates the internal channel state machine to the one as described within the spec and currently implemented within the rest of the other Lightning implementations. At a high level the following modifications have been made: * When signing we no loner include the index of the remote party’s log that our signature covers. Instead we include ALL of our current updates, but only the updates of the remote party that we’ve ACK’d. * A pending change is considered ACK’d once a revocation message has been received, locking in the changes in the remote party’s commitment transaction. * When sending a new commitment, we remember the index of our log at that point so we can mark that portion of the log as ACK’d once we receive a revocation message from the remote party. * When receiving a new commitment signature, we include ALL of the remote party’s changes that we’ve received but only our set of changes that’ve been ACK’d by the remote party. * Implicitly a revocation message now also implicitly serves to ACK all the changes that were included in the CommitSig message received before it. The resulting change is a rather minor diff. However, with this state machine it’s important to note that the order to sig/revoke messages has been swapped. A proper exchange now looks like the following: * Alice -> Add, Add, Add * Alice -> Sig * Revoke <- Bob * Sig <- Bob * Alice -> Revoke One other thing that’s worth noting is that with this state machine, since what’s included in an update is implicit, both side may need to at times send a new commitment update in the case of a concurrent state transition initiated by both sides. Finally, all counters/indexes have been made 64-bit integers in order to properly match the spec.
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if err := lc.validateCommitmentSanity(lc.remoteUpdateLog.logIndex,
lc.localUpdateLog.logIndex, true, false, true); err != nil {
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return 0, err
}
pd := &PaymentDescriptor{
EntryType: Add,
RHash: PaymentHash(htlc.PaymentHash),
Timeout: htlc.Expiry,
Amount: htlc.Amount,
LogIndex: lc.remoteUpdateLog.logIndex,
HtlcIndex: lc.remoteUpdateLog.htlcCounter,
}
lc.remoteUpdateLog.appendHtlc(pd)
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lc.rHashMap[pd.RHash] = append(lc.rHashMap[pd.RHash], pd)
return pd.HtlcIndex, nil
}
2016-10-15 16:18:38 +03:00
// SettleHTLC attempts to settle an existing outstanding received HTLC. The
// remote log index of the HTLC settled is returned in order to facilitate
// creating the corresponding wire message. In the case the supplied preimage
// is invalid, an error is returned. Additionally, the value of the settled
// HTLC is also returned.
func (lc *LightningChannel) SettleHTLC(preimage [32]byte) (uint64,
lnwire.MilliSatoshi, error) {
lc.Lock()
defer lc.Unlock()
paymentHash := sha256.Sum256(preimage[:])
targetHTLCs, ok := lc.rHashMap[paymentHash]
if !ok {
return 0, 0, fmt.Errorf("invalid payment hash(%v)",
hex.EncodeToString(paymentHash[:]))
}
targetHTLC := targetHTLCs[0]
pd := &PaymentDescriptor{
Amount: targetHTLC.Amount,
RPreimage: preimage,
LogIndex: lc.localUpdateLog.logIndex,
ParentIndex: targetHTLC.HtlcIndex,
EntryType: Settle,
}
lnwallet: update state machine to the version within the spec This commit updates the internal channel state machine to the one as described within the spec and currently implemented within the rest of the other Lightning implementations. At a high level the following modifications have been made: * When signing we no loner include the index of the remote party’s log that our signature covers. Instead we include ALL of our current updates, but only the updates of the remote party that we’ve ACK’d. * A pending change is considered ACK’d once a revocation message has been received, locking in the changes in the remote party’s commitment transaction. * When sending a new commitment, we remember the index of our log at that point so we can mark that portion of the log as ACK’d once we receive a revocation message from the remote party. * When receiving a new commitment signature, we include ALL of the remote party’s changes that we’ve received but only our set of changes that’ve been ACK’d by the remote party. * Implicitly a revocation message now also implicitly serves to ACK all the changes that were included in the CommitSig message received before it. The resulting change is a rather minor diff. However, with this state machine it’s important to note that the order to sig/revoke messages has been swapped. A proper exchange now looks like the following: * Alice -> Add, Add, Add * Alice -> Sig * Revoke <- Bob * Sig <- Bob * Alice -> Revoke One other thing that’s worth noting is that with this state machine, since what’s included in an update is implicit, both side may need to at times send a new commitment update in the case of a concurrent state transition initiated by both sides. Finally, all counters/indexes have been made 64-bit integers in order to properly match the spec.
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lc.localUpdateLog.appendUpdate(pd)
lc.rHashMap[paymentHash][0] = nil
lc.rHashMap[paymentHash] = lc.rHashMap[paymentHash][1:]
if len(lc.rHashMap[paymentHash]) == 0 {
delete(lc.rHashMap, paymentHash)
}
lc.availableLocalBalance += pd.Amount
return targetHTLC.HtlcIndex, targetHTLC.Amount, nil
2016-07-06 03:01:55 +03:00
}
// ReceiveHTLCSettle attempts to settle an existing outgoing HTLC indexed by an
// index into the local log. If the specified index doesn't exist within the
// log, and error is returned. Similarly if the preimage is invalid w.r.t to
// the referenced of then a distinct error is returned.
func (lc *LightningChannel) ReceiveHTLCSettle(preimage [32]byte, htlcIndex uint64) error {
lc.Lock()
defer lc.Unlock()
paymentHash := sha256.Sum256(preimage[:])
htlc := lc.localUpdateLog.lookupHtlc(htlcIndex)
lnwallet: update state machine to the version within the spec This commit updates the internal channel state machine to the one as described within the spec and currently implemented within the rest of the other Lightning implementations. At a high level the following modifications have been made: * When signing we no loner include the index of the remote party’s log that our signature covers. Instead we include ALL of our current updates, but only the updates of the remote party that we’ve ACK’d. * A pending change is considered ACK’d once a revocation message has been received, locking in the changes in the remote party’s commitment transaction. * When sending a new commitment, we remember the index of our log at that point so we can mark that portion of the log as ACK’d once we receive a revocation message from the remote party. * When receiving a new commitment signature, we include ALL of the remote party’s changes that we’ve received but only our set of changes that’ve been ACK’d by the remote party. * Implicitly a revocation message now also implicitly serves to ACK all the changes that were included in the CommitSig message received before it. The resulting change is a rather minor diff. However, with this state machine it’s important to note that the order to sig/revoke messages has been swapped. A proper exchange now looks like the following: * Alice -> Add, Add, Add * Alice -> Sig * Revoke <- Bob * Sig <- Bob * Alice -> Revoke One other thing that’s worth noting is that with this state machine, since what’s included in an update is implicit, both side may need to at times send a new commitment update in the case of a concurrent state transition initiated by both sides. Finally, all counters/indexes have been made 64-bit integers in order to properly match the spec.
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if htlc == nil {
return fmt.Errorf("non existant log entry")
}
if !bytes.Equal(htlc.RHash[:], paymentHash[:]) {
return fmt.Errorf("invalid payment hash(%v)",
hex.EncodeToString(paymentHash[:]))
}
pd := &PaymentDescriptor{
Amount: htlc.Amount,
RPreimage: preimage,
ParentIndex: htlc.HtlcIndex,
RHash: htlc.RHash,
LogIndex: lc.remoteUpdateLog.logIndex,
EntryType: Settle,
}
lnwallet: update state machine to the version within the spec This commit updates the internal channel state machine to the one as described within the spec and currently implemented within the rest of the other Lightning implementations. At a high level the following modifications have been made: * When signing we no loner include the index of the remote party’s log that our signature covers. Instead we include ALL of our current updates, but only the updates of the remote party that we’ve ACK’d. * A pending change is considered ACK’d once a revocation message has been received, locking in the changes in the remote party’s commitment transaction. * When sending a new commitment, we remember the index of our log at that point so we can mark that portion of the log as ACK’d once we receive a revocation message from the remote party. * When receiving a new commitment signature, we include ALL of the remote party’s changes that we’ve received but only our set of changes that’ve been ACK’d by the remote party. * Implicitly a revocation message now also implicitly serves to ACK all the changes that were included in the CommitSig message received before it. The resulting change is a rather minor diff. However, with this state machine it’s important to note that the order to sig/revoke messages has been swapped. A proper exchange now looks like the following: * Alice -> Add, Add, Add * Alice -> Sig * Revoke <- Bob * Sig <- Bob * Alice -> Revoke One other thing that’s worth noting is that with this state machine, since what’s included in an update is implicit, both side may need to at times send a new commitment update in the case of a concurrent state transition initiated by both sides. Finally, all counters/indexes have been made 64-bit integers in order to properly match the spec.
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lc.remoteUpdateLog.appendUpdate(pd)
return nil
}
lnwallet: update state machine to the version within the spec This commit updates the internal channel state machine to the one as described within the spec and currently implemented within the rest of the other Lightning implementations. At a high level the following modifications have been made: * When signing we no loner include the index of the remote party’s log that our signature covers. Instead we include ALL of our current updates, but only the updates of the remote party that we’ve ACK’d. * A pending change is considered ACK’d once a revocation message has been received, locking in the changes in the remote party’s commitment transaction. * When sending a new commitment, we remember the index of our log at that point so we can mark that portion of the log as ACK’d once we receive a revocation message from the remote party. * When receiving a new commitment signature, we include ALL of the remote party’s changes that we’ve received but only our set of changes that’ve been ACK’d by the remote party. * Implicitly a revocation message now also implicitly serves to ACK all the changes that were included in the CommitSig message received before it. The resulting change is a rather minor diff. However, with this state machine it’s important to note that the order to sig/revoke messages has been swapped. A proper exchange now looks like the following: * Alice -> Add, Add, Add * Alice -> Sig * Revoke <- Bob * Sig <- Bob * Alice -> Revoke One other thing that’s worth noting is that with this state machine, since what’s included in an update is implicit, both side may need to at times send a new commitment update in the case of a concurrent state transition initiated by both sides. Finally, all counters/indexes have been made 64-bit integers in order to properly match the spec.
2017-02-21 04:55:33 +03:00
// FailHTLC attempts to fail a targeted HTLC by its payment hash, inserting an
// entry which will remove the target log entry within the next commitment
// update. This method is intended to be called in order to cancel in
// _incoming_ HTLC.
//
// TODO(roasbeef): add value as well?
lnwallet: update state machine to the version within the spec This commit updates the internal channel state machine to the one as described within the spec and currently implemented within the rest of the other Lightning implementations. At a high level the following modifications have been made: * When signing we no loner include the index of the remote party’s log that our signature covers. Instead we include ALL of our current updates, but only the updates of the remote party that we’ve ACK’d. * A pending change is considered ACK’d once a revocation message has been received, locking in the changes in the remote party’s commitment transaction. * When sending a new commitment, we remember the index of our log at that point so we can mark that portion of the log as ACK’d once we receive a revocation message from the remote party. * When receiving a new commitment signature, we include ALL of the remote party’s changes that we’ve received but only our set of changes that’ve been ACK’d by the remote party. * Implicitly a revocation message now also implicitly serves to ACK all the changes that were included in the CommitSig message received before it. The resulting change is a rather minor diff. However, with this state machine it’s important to note that the order to sig/revoke messages has been swapped. A proper exchange now looks like the following: * Alice -> Add, Add, Add * Alice -> Sig * Revoke <- Bob * Sig <- Bob * Alice -> Revoke One other thing that’s worth noting is that with this state machine, since what’s included in an update is implicit, both side may need to at times send a new commitment update in the case of a concurrent state transition initiated by both sides. Finally, all counters/indexes have been made 64-bit integers in order to properly match the spec.
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func (lc *LightningChannel) FailHTLC(rHash [32]byte) (uint64, error) {
lc.Lock()
defer lc.Unlock()
addEntries, ok := lc.rHashMap[rHash]
if !ok {
lnwallet: update state machine to the version within the spec This commit updates the internal channel state machine to the one as described within the spec and currently implemented within the rest of the other Lightning implementations. At a high level the following modifications have been made: * When signing we no loner include the index of the remote party’s log that our signature covers. Instead we include ALL of our current updates, but only the updates of the remote party that we’ve ACK’d. * A pending change is considered ACK’d once a revocation message has been received, locking in the changes in the remote party’s commitment transaction. * When sending a new commitment, we remember the index of our log at that point so we can mark that portion of the log as ACK’d once we receive a revocation message from the remote party. * When receiving a new commitment signature, we include ALL of the remote party’s changes that we’ve received but only our set of changes that’ve been ACK’d by the remote party. * Implicitly a revocation message now also implicitly serves to ACK all the changes that were included in the CommitSig message received before it. The resulting change is a rather minor diff. However, with this state machine it’s important to note that the order to sig/revoke messages has been swapped. A proper exchange now looks like the following: * Alice -> Add, Add, Add * Alice -> Sig * Revoke <- Bob * Sig <- Bob * Alice -> Revoke One other thing that’s worth noting is that with this state machine, since what’s included in an update is implicit, both side may need to at times send a new commitment update in the case of a concurrent state transition initiated by both sides. Finally, all counters/indexes have been made 64-bit integers in order to properly match the spec.
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return 0, fmt.Errorf("unable to find HTLC to fail")
}
addEntry := addEntries[0]
pd := &PaymentDescriptor{
Amount: addEntry.Amount,
RHash: addEntry.RHash,
ParentIndex: addEntry.HtlcIndex,
LogIndex: lc.localUpdateLog.logIndex,
lnwallet: update state machine to the version within the spec This commit updates the internal channel state machine to the one as described within the spec and currently implemented within the rest of the other Lightning implementations. At a high level the following modifications have been made: * When signing we no loner include the index of the remote party’s log that our signature covers. Instead we include ALL of our current updates, but only the updates of the remote party that we’ve ACK’d. * A pending change is considered ACK’d once a revocation message has been received, locking in the changes in the remote party’s commitment transaction. * When sending a new commitment, we remember the index of our log at that point so we can mark that portion of the log as ACK’d once we receive a revocation message from the remote party. * When receiving a new commitment signature, we include ALL of the remote party’s changes that we’ve received but only our set of changes that’ve been ACK’d by the remote party. * Implicitly a revocation message now also implicitly serves to ACK all the changes that were included in the CommitSig message received before it. The resulting change is a rather minor diff. However, with this state machine it’s important to note that the order to sig/revoke messages has been swapped. A proper exchange now looks like the following: * Alice -> Add, Add, Add * Alice -> Sig * Revoke <- Bob * Sig <- Bob * Alice -> Revoke One other thing that’s worth noting is that with this state machine, since what’s included in an update is implicit, both side may need to at times send a new commitment update in the case of a concurrent state transition initiated by both sides. Finally, all counters/indexes have been made 64-bit integers in order to properly match the spec.
2017-02-21 04:55:33 +03:00
EntryType: Fail,
}
lnwallet: update state machine to the version within the spec This commit updates the internal channel state machine to the one as described within the spec and currently implemented within the rest of the other Lightning implementations. At a high level the following modifications have been made: * When signing we no loner include the index of the remote party’s log that our signature covers. Instead we include ALL of our current updates, but only the updates of the remote party that we’ve ACK’d. * A pending change is considered ACK’d once a revocation message has been received, locking in the changes in the remote party’s commitment transaction. * When sending a new commitment, we remember the index of our log at that point so we can mark that portion of the log as ACK’d once we receive a revocation message from the remote party. * When receiving a new commitment signature, we include ALL of the remote party’s changes that we’ve received but only our set of changes that’ve been ACK’d by the remote party. * Implicitly a revocation message now also implicitly serves to ACK all the changes that were included in the CommitSig message received before it. The resulting change is a rather minor diff. However, with this state machine it’s important to note that the order to sig/revoke messages has been swapped. A proper exchange now looks like the following: * Alice -> Add, Add, Add * Alice -> Sig * Revoke <- Bob * Sig <- Bob * Alice -> Revoke One other thing that’s worth noting is that with this state machine, since what’s included in an update is implicit, both side may need to at times send a new commitment update in the case of a concurrent state transition initiated by both sides. Finally, all counters/indexes have been made 64-bit integers in order to properly match the spec.
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lc.localUpdateLog.appendUpdate(pd)
lc.rHashMap[rHash][0] = nil
lc.rHashMap[rHash] = lc.rHashMap[rHash][1:]
if len(lc.rHashMap[rHash]) == 0 {
delete(lc.rHashMap, rHash)
}
return addEntry.HtlcIndex, nil
}
// ReceiveFailHTLC attempts to cancel a targeted HTLC by its log htlc,
// inserting an entry which will remove the target log entry within the next
// commitment update. This method should be called in response to the upstream
// party cancelling an outgoing HTLC. The value of the failed HTLC is returned
// along with an error indicating success.
func (lc *LightningChannel) ReceiveFailHTLC(htlcIndex uint64) (lnwire.MilliSatoshi, error) {
lc.Lock()
defer lc.Unlock()
htlc := lc.localUpdateLog.lookupHtlc(htlcIndex)
lnwallet: update state machine to the version within the spec This commit updates the internal channel state machine to the one as described within the spec and currently implemented within the rest of the other Lightning implementations. At a high level the following modifications have been made: * When signing we no loner include the index of the remote party’s log that our signature covers. Instead we include ALL of our current updates, but only the updates of the remote party that we’ve ACK’d. * A pending change is considered ACK’d once a revocation message has been received, locking in the changes in the remote party’s commitment transaction. * When sending a new commitment, we remember the index of our log at that point so we can mark that portion of the log as ACK’d once we receive a revocation message from the remote party. * When receiving a new commitment signature, we include ALL of the remote party’s changes that we’ve received but only our set of changes that’ve been ACK’d by the remote party. * Implicitly a revocation message now also implicitly serves to ACK all the changes that were included in the CommitSig message received before it. The resulting change is a rather minor diff. However, with this state machine it’s important to note that the order to sig/revoke messages has been swapped. A proper exchange now looks like the following: * Alice -> Add, Add, Add * Alice -> Sig * Revoke <- Bob * Sig <- Bob * Alice -> Revoke One other thing that’s worth noting is that with this state machine, since what’s included in an update is implicit, both side may need to at times send a new commitment update in the case of a concurrent state transition initiated by both sides. Finally, all counters/indexes have been made 64-bit integers in order to properly match the spec.
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if htlc == nil {
return 0, fmt.Errorf("unable to find HTLC to fail")
}
pd := &PaymentDescriptor{
Amount: htlc.Amount,
RHash: htlc.RHash,
ParentIndex: htlc.HtlcIndex,
LogIndex: lc.remoteUpdateLog.logIndex,
lnwallet: update state machine to the version within the spec This commit updates the internal channel state machine to the one as described within the spec and currently implemented within the rest of the other Lightning implementations. At a high level the following modifications have been made: * When signing we no loner include the index of the remote party’s log that our signature covers. Instead we include ALL of our current updates, but only the updates of the remote party that we’ve ACK’d. * A pending change is considered ACK’d once a revocation message has been received, locking in the changes in the remote party’s commitment transaction. * When sending a new commitment, we remember the index of our log at that point so we can mark that portion of the log as ACK’d once we receive a revocation message from the remote party. * When receiving a new commitment signature, we include ALL of the remote party’s changes that we’ve received but only our set of changes that’ve been ACK’d by the remote party. * Implicitly a revocation message now also implicitly serves to ACK all the changes that were included in the CommitSig message received before it. The resulting change is a rather minor diff. However, with this state machine it’s important to note that the order to sig/revoke messages has been swapped. A proper exchange now looks like the following: * Alice -> Add, Add, Add * Alice -> Sig * Revoke <- Bob * Sig <- Bob * Alice -> Revoke One other thing that’s worth noting is that with this state machine, since what’s included in an update is implicit, both side may need to at times send a new commitment update in the case of a concurrent state transition initiated by both sides. Finally, all counters/indexes have been made 64-bit integers in order to properly match the spec.
2017-02-21 04:55:33 +03:00
EntryType: Fail,
}
lnwallet: update state machine to the version within the spec This commit updates the internal channel state machine to the one as described within the spec and currently implemented within the rest of the other Lightning implementations. At a high level the following modifications have been made: * When signing we no loner include the index of the remote party’s log that our signature covers. Instead we include ALL of our current updates, but only the updates of the remote party that we’ve ACK’d. * A pending change is considered ACK’d once a revocation message has been received, locking in the changes in the remote party’s commitment transaction. * When sending a new commitment, we remember the index of our log at that point so we can mark that portion of the log as ACK’d once we receive a revocation message from the remote party. * When receiving a new commitment signature, we include ALL of the remote party’s changes that we’ve received but only our set of changes that’ve been ACK’d by the remote party. * Implicitly a revocation message now also implicitly serves to ACK all the changes that were included in the CommitSig message received before it. The resulting change is a rather minor diff. However, with this state machine it’s important to note that the order to sig/revoke messages has been swapped. A proper exchange now looks like the following: * Alice -> Add, Add, Add * Alice -> Sig * Revoke <- Bob * Sig <- Bob * Alice -> Revoke One other thing that’s worth noting is that with this state machine, since what’s included in an update is implicit, both side may need to at times send a new commitment update in the case of a concurrent state transition initiated by both sides. Finally, all counters/indexes have been made 64-bit integers in order to properly match the spec.
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lc.remoteUpdateLog.appendUpdate(pd)
lc.availableLocalBalance += pd.Amount
return htlc.Amount, nil
2016-07-06 03:01:55 +03:00
}
// ChannelPoint returns the outpoint of the original funding transaction which
// created this active channel. This outpoint is used throughout various
// subsystems to uniquely identify an open channel.
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func (lc *LightningChannel) ChannelPoint() *wire.OutPoint {
lc.RLock()
defer lc.RUnlock()
return &lc.channelState.FundingOutpoint
2016-07-06 03:01:55 +03:00
}
// ShortChanID returns the short channel ID for the channel. The short channel
// ID encodes the exact location in the main chain that the original
// funding output can be found.
func (lc *LightningChannel) ShortChanID() lnwire.ShortChannelID {
lc.RLock()
defer lc.RUnlock()
return lc.channelState.ShortChanID
}
// genHtlcScript generates the proper P2WSH public key scripts for the
// HTLC output modified by two-bits denoting if this is an incoming HTLC, and
// if the HTLC is being applied to their commitment transaction or ours.
func (lc *LightningChannel) genHtlcScript(isIncoming, ourCommit bool,
timeout uint32, rHash [32]byte, keyRing *commitmentKeyRing,
) ([]byte, []byte, error) {
var (
witnessScript []byte
err error
)
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// Generate the proper redeem scripts for the HTLC output modified by
// two-bits denoting if this is an incoming HTLC, and if the HTLC is
// being applied to their commitment transaction or ours.
switch {
// The HTLC is paying to us, and being applied to our commitment
// transaction. So we need to use the receiver's version of HTLC the
// script.
case isIncoming && ourCommit:
witnessScript, err = receiverHTLCScript(timeout, keyRing.remoteKey,
keyRing.localKey, keyRing.revocationKey, rHash[:])
2016-07-06 03:01:55 +03:00
// We're being paid via an HTLC by the remote party, and the HTLC is
// being added to their commitment transaction, so we use the sender's
// version of the HTLC script.
case isIncoming && !ourCommit:
witnessScript, err = senderHTLCScript(keyRing.remoteKey,
keyRing.localKey, keyRing.revocationKey, rHash[:])
2016-07-06 03:01:55 +03:00
// We're sending an HTLC which is being added to our commitment
// transaction. Therefore, we need to use the sender's version of the
// HTLC script.
case !isIncoming && ourCommit:
witnessScript, err = senderHTLCScript(keyRing.localKey,
keyRing.remoteKey, keyRing.revocationKey, rHash[:])
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// Finally, we're paying the remote party via an HTLC, which is being
// added to their commitment transaction. Therefore, we use the
// receiver's version of the HTLC script.
case !isIncoming && !ourCommit:
witnessScript, err = receiverHTLCScript(timeout, keyRing.localKey,
keyRing.remoteKey, keyRing.revocationKey, rHash[:])
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}
if err != nil {
return nil, nil, err
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}
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// Now that we have the redeem scripts, create the P2WSH public key
// script for the output itself.
htlcP2WSH, err := witnessScriptHash(witnessScript)
if err != nil {
return nil, nil, err
}
return htlcP2WSH, witnessScript, nil
}
// 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. 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,
isIncoming bool, paymentDesc *PaymentDescriptor, keyRing *commitmentKeyRing,
) error {
timeout := paymentDesc.Timeout
rHash := paymentDesc.RHash
p2wsh, witnessScript, err := lc.genHtlcScript(isIncoming, ourCommit,
timeout, rHash, keyRing)
2016-07-06 03:01:55 +03:00
if err != nil {
return err
}
// Add the new HTLC outputs to the respective commitment transactions.
amountPending := int64(paymentDesc.Amount.ToSatoshis())
commitTx.AddTxOut(wire.NewTxOut(amountPending, p2wsh))
// Store the pkScript of this particular PaymentDescriptor so we can
// quickly locate it within the commitment transaction later.
lnwallet: fix bug that retrieves incorrect pkScript in toChannelDelta() Description of bug: When calling ReceiveNewCommitment() we will progress through methods fetchCommitmentView and addHTLC which will add HTLC outputs to the commitment transaction in the local commitment chain and save the pkScript to the relevant PaymentDescriptor which resides in the corresponding updateLog. Finally the local commitment will be added to the local commitment chain. When the same user next calls SignNextCommitment we will again progress through fetchCommitmentView and addHTLC. In addHTLC we will now overwrite the pkScripts in the PaymentDescriptors with the pkScript from the context of the remote commitment. When we later call RevokeCurrentCommitment and proceed into toChannelDelta, we will not be able to find the correct pkScript in the PaymentDescriptor to match it against the outputs in the commitment transaction. This will lead to the nested function locateOutputIndex returning incorrect values. Fixing the bug: We introduce three new fields in PaymentDescriptor: * ourPkScript * theirPkScript * theirPrevPkScript ourPkScript will include the pkScript for the HTLC from the context of the local commitment. theirPkScript will take the value of the latest pkScript for the HTLC from the context of the remote commitment. theirPrevPkScript will take the second-latest pkScript for the HTLC from the context of the remote commitment. This is the value we use in toChannelDelta when we save a revoked commitment from our peer. The appropriate value of these fields are set in the addHTLC method. Additionally we pass a boolean value to toChannelDelta so we know whether we are operating on a local or remote commitment and grab the correct pkScript in locateUpdateIndex.
2017-01-20 14:37:30 +03:00
if ourCommit {
paymentDesc.ourPkScript = p2wsh
paymentDesc.ourWitnessScript = witnessScript
lnwallet: fix bug that retrieves incorrect pkScript in toChannelDelta() Description of bug: When calling ReceiveNewCommitment() we will progress through methods fetchCommitmentView and addHTLC which will add HTLC outputs to the commitment transaction in the local commitment chain and save the pkScript to the relevant PaymentDescriptor which resides in the corresponding updateLog. Finally the local commitment will be added to the local commitment chain. When the same user next calls SignNextCommitment we will again progress through fetchCommitmentView and addHTLC. In addHTLC we will now overwrite the pkScripts in the PaymentDescriptors with the pkScript from the context of the remote commitment. When we later call RevokeCurrentCommitment and proceed into toChannelDelta, we will not be able to find the correct pkScript in the PaymentDescriptor to match it against the outputs in the commitment transaction. This will lead to the nested function locateOutputIndex returning incorrect values. Fixing the bug: We introduce three new fields in PaymentDescriptor: * ourPkScript * theirPkScript * theirPrevPkScript ourPkScript will include the pkScript for the HTLC from the context of the local commitment. theirPkScript will take the value of the latest pkScript for the HTLC from the context of the remote commitment. theirPrevPkScript will take the second-latest pkScript for the HTLC from the context of the remote commitment. This is the value we use in toChannelDelta when we save a revoked commitment from our peer. The appropriate value of these fields are set in the addHTLC method. Additionally we pass a boolean value to toChannelDelta so we know whether we are operating on a local or remote commitment and grab the correct pkScript in locateUpdateIndex.
2017-01-20 14:37:30 +03:00
} else {
paymentDesc.theirPkScript = p2wsh
paymentDesc.theirWitnessScript = witnessScript
lnwallet: fix bug that retrieves incorrect pkScript in toChannelDelta() Description of bug: When calling ReceiveNewCommitment() we will progress through methods fetchCommitmentView and addHTLC which will add HTLC outputs to the commitment transaction in the local commitment chain and save the pkScript to the relevant PaymentDescriptor which resides in the corresponding updateLog. Finally the local commitment will be added to the local commitment chain. When the same user next calls SignNextCommitment we will again progress through fetchCommitmentView and addHTLC. In addHTLC we will now overwrite the pkScripts in the PaymentDescriptors with the pkScript from the context of the remote commitment. When we later call RevokeCurrentCommitment and proceed into toChannelDelta, we will not be able to find the correct pkScript in the PaymentDescriptor to match it against the outputs in the commitment transaction. This will lead to the nested function locateOutputIndex returning incorrect values. Fixing the bug: We introduce three new fields in PaymentDescriptor: * ourPkScript * theirPkScript * theirPrevPkScript ourPkScript will include the pkScript for the HTLC from the context of the local commitment. theirPkScript will take the value of the latest pkScript for the HTLC from the context of the remote commitment. theirPrevPkScript will take the second-latest pkScript for the HTLC from the context of the remote commitment. This is the value we use in toChannelDelta when we save a revoked commitment from our peer. The appropriate value of these fields are set in the addHTLC method. Additionally we pass a boolean value to toChannelDelta so we know whether we are operating on a local or remote commitment and grab the correct pkScript in locateUpdateIndex.
2017-01-20 14:37:30 +03:00
}
return nil
}
// getSignedCommitTx function take the latest commitment transaction and populate
// it with witness data.
func (lc *LightningChannel) getSignedCommitTx() (*wire.MsgTx, error) {
// Fetch the current commitment transaction, along with their signature
// for the transaction.
commitTx := lc.channelState.CommitTx
theirSig := append(lc.channelState.CommitSig, byte(txscript.SigHashAll))
// With this, we then generate the full witness so the caller can
// broadcast a fully signed transaction.
lc.signDesc.SigHashes = txscript.NewTxSigHashes(&commitTx)
ourSigRaw, err := lc.signer.SignOutputRaw(&commitTx, lc.signDesc)
if err != nil {
return nil, err
}
ourSig := append(ourSigRaw, byte(txscript.SigHashAll))
// With the final signature generated, create the witness stack
// required to spend from the multi-sig output.
ourKey := lc.localChanCfg.MultiSigKey.SerializeCompressed()
theirKey := lc.remoteChanCfg.MultiSigKey.SerializeCompressed()
commitTx.TxIn[0].Witness = SpendMultiSig(lc.FundingWitnessScript, ourKey,
ourSig, theirKey, theirSig)
return &commitTx, nil
}
// UnilateralCloseSummary describes the details of a detected unilateral
// channel closure. This includes the information about with which
// transactions, and block the channel was unilaterally closed, as well as
// summarization details concerning the _state_ of the channel at the point of
// channel closure. Additionally, if we had a commitment output above dust on
// the remote party's commitment transaction, the necessary a SignDescriptor
// with the material necessary to seep the output are returned. Finally, if we
// had any outgoing HTLC's within the commitment transaction, then an
// OutgoingHtlcResolution for each output will included.
type UnilateralCloseSummary struct {
// SpendDetail is a struct that describes how and when the commitment
// output was spent.
*chainntnfs.SpendDetail
// ChannelCloseSummary is a struct describing the final state of the
// channel and in which state is was closed.
channeldb.ChannelCloseSummary
// SelfOutPoint is the full outpoint that points to our non-delayed
// pay-to-self output within the commitment transaction of the remote
// party.
SelfOutPoint *wire.OutPoint
// SelfOutputSignDesc is a fully populated sign descriptor capable of
// generating a valid signature to sweep the output paying to us
SelfOutputSignDesc *SignDescriptor
// MaturityDelay is the relative time-lock, in blocks for all outputs
// that pay to the local party within the broadcast commitment
// transaction.
MaturityDelay uint32
// HtlcResolutions is a slice of HTLC resolutions which allows the
// local node to sweep any outgoing HTLC"s after the timeout period has
// passed.
HtlcResolutions []OutgoingHtlcResolution
}
// OutgoingHtlcResolution houses the information necessary to sweep any outging
// HTLC's after their contract has expired. This struct will be needed in one
// of tow cases: the local party force closes the commitment transaction or the
// remote party unilaterally closes with their version of the commitment
// transaction.
type OutgoingHtlcResolution struct {
// Expiry the absolute timeout of the HTLC. This value is expressed in
// block height, meaning after this height the HLTC can be swept.
Expiry uint32
// SignedTimeoutTx is the fully signed HTLC timeout transaction. This
// must be broadcast immediately after timeout has passed. Once this
// has been confirmed, the HTLC output will transition into the
// delay+claim state.
SignedTimeoutTx *wire.MsgTx
// SweepSignDesc is a sign descriptor that has been populated with the
// necessary items required to spend the sole output of the above
// transaction.
SweepSignDesc SignDescriptor
}
// newHtlcResolution generates a new HTLC resolution capable of allowing the
// caller to sweep an outgoing HTLC present on either their, or the remote
// party's commitment transaction.
func newHtlcResolution(signer Signer, localChanCfg *channeldb.ChannelConfig,
commitHash chainhash.Hash, htlc *channeldb.HTLC, keyRing *commitmentKeyRing,
feePewKw, dustLimit btcutil.Amount, csvDelay uint32,
) (*OutgoingHtlcResolution, error) {
op := wire.OutPoint{
Hash: commitHash,
Index: uint32(htlc.OutputIndex),
}
// In order to properly reconstruct the HTLC transaction, we'll need to
// re-calculate the fee required at this state, so we can add the
// correct output value amount to the transaction.
htlcFee := htlcTimeoutFee(feePewKw)
secondLevelOutputAmt := htlc.Amt.ToSatoshis() - htlcFee
// With the fee calculated, re-construct the second level timeout
// transaction.
timeoutTx, err := createHtlcTimeoutTx(
op, secondLevelOutputAmt, htlc.RefundTimeout, csvDelay,
keyRing.revocationKey, keyRing.delayKey,
)
if err != nil {
return nil, err
}
// With the transaction created, we can generate a sign descriptor
// that's capable of generating the signature required to spend the
// HTLC output using the timeout transaction.
htlcCreationScript, err := senderHTLCScript(keyRing.localKey,
keyRing.remoteKey, keyRing.revocationKey, htlc.RHash[:])
if err != nil {
return nil, err
}
timeoutSignDesc := SignDescriptor{
PubKey: localChanCfg.PaymentBasePoint,
SingleTweak: keyRing.localKeyTweak,
WitnessScript: htlcCreationScript,
Output: &wire.TxOut{
Value: int64(htlc.Amt.ToSatoshis()),
},
HashType: txscript.SigHashAll,
SigHashes: txscript.NewTxSigHashes(timeoutTx),
InputIndex: 0,
}
// With the sign desc created, we can now construct the full witness
// for the timeout transaction, and populate it as well.
timeoutWitness, err := senderHtlcSpendTimeout(
htlc.Signature, signer, &timeoutSignDesc, timeoutTx)
if err != nil {
return nil, err
}
timeoutTx.TxIn[0].Witness = timeoutWitness
// Finally, we'll generate the script output that the timeout
// transaction creates so we can generate the signDesc required to
// complete the claim process after a delay period.
htlcSweepScript, err := secondLevelHtlcScript(
keyRing.revocationKey, keyRing.delayKey, csvDelay,
)
if err != nil {
return nil, err
}
htlcScriptHash, err := witnessScriptHash(htlcSweepScript)
if err != nil {
return nil, err
}
// TODO: Signing with the delay key is wrong for remote commitments
localDelayTweak := SingleTweakBytes(keyRing.commitPoint,
localChanCfg.DelayBasePoint)
return &OutgoingHtlcResolution{
Expiry: htlc.RefundTimeout,
SignedTimeoutTx: timeoutTx,
SweepSignDesc: SignDescriptor{
PubKey: localChanCfg.DelayBasePoint,
SingleTweak: localDelayTweak,
WitnessScript: htlcSweepScript,
Output: &wire.TxOut{
PkScript: htlcScriptHash,
Value: int64(secondLevelOutputAmt),
},
HashType: txscript.SigHashAll,
},
}, nil
}
// extractHtlcResolutions creates a series of outgoing HTLC resolutions, and
// the local key used when generating the HTLC scrips. This function is to be
// used in two cases: force close, or a unilateral close.
func extractHtlcResolutions(feePerKw btcutil.Amount, ourCommit bool,
signer Signer, htlcs []*channeldb.HTLC, keyRing *commitmentKeyRing,
localChanCfg, remoteChanCfg *channeldb.ChannelConfig,
commitHash chainhash.Hash) ([]OutgoingHtlcResolution, error) {
dustLimit := remoteChanCfg.DustLimit
csvDelay := remoteChanCfg.CsvDelay
if ourCommit {
dustLimit = localChanCfg.DustLimit
csvDelay = localChanCfg.CsvDelay
}
htlcResolutions := make([]OutgoingHtlcResolution, 0, len(htlcs))
for _, htlc := range htlcs {
// Skip any incoming HTLC's, as unless we have the pre-image to
// spend them, they'll eventually be swept by the party that
// offered the HTLC after the timeout.
if htlc.Incoming {
continue
}
// We'll also skip any HTLC's which were dust on the commitment
// transaction, as these don't have a corresponding output
// within the commitment transaction.
if htlcIsDust(htlc.Incoming, ourCommit, feePerKw,
htlc.Amt.ToSatoshis(), dustLimit) {
continue
}
ohr, err := newHtlcResolution(
signer, localChanCfg, commitHash, htlc, keyRing,
feePerKw, dustLimit, uint32(csvDelay),
)
if err != nil {
return nil, err
}
// TODO(roasbeef): needs to point to proper amount including
htlcResolutions = append(htlcResolutions, *ohr)
}
return htlcResolutions, nil
}
// ForceCloseSummary describes the final commitment state before the channel is
// 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.
type ForceCloseSummary struct {
// ChanPoint is the outpoint that created the channel which has been
// force closed.
ChanPoint wire.OutPoint
// SelfOutpoint is the output created by the above close tx which is
// spendable by us after a relative time delay.
SelfOutpoint wire.OutPoint
// CloseTx is the transaction which closed the channel on-chain. If we
// initiate the force close, then this'll be our latest commitment
// state. Otherwise, this'll be the state that the remote peer
// broadcasted on-chain.
CloseTx *wire.MsgTx
// SelfOutputSignDesc is a fully populated sign descriptor capable of
// generating a valid signature to sweep the self output.
//
// NOTE: If the commitment delivery output of the force closing party
// is below the dust limit, then this will be nil.
SelfOutputSignDesc *SignDescriptor
// SelfOutputMaturity is the relative maturity period before the above
// output can be claimed.
SelfOutputMaturity uint32
// HtlcResolutions is a slice of HTLC resolutions which allows the
// local node to sweep any outgoing HTLC"s after the timeout period has
// passed.
HtlcResolutions []OutgoingHtlcResolution
}
// ForceClose executes a unilateral closure of the transaction at the current
// lowest commitment height of the channel. Following a force closure, all
// state transitions, or modifications to the state update logs will be
// rejected. Additionally, this function also returns a ForceCloseSummary which
// includes the necessary details required to sweep all the time-locked within
// the commitment transaction.
//
// TODO(roasbeef): all methods need to abort if in dispute state
// TODO(roasbeef): method to generate CloseSummaries for when the remote peer
// does a unilateral close
func (lc *LightningChannel) ForceClose() (*ForceCloseSummary, error) {
lc.Lock()
defer lc.Unlock()
// Set the channel state to indicate that the channel is now in a
// contested state.
lc.status = channelDispute
commitTx, err := lc.getSignedCommitTx()
if err != nil {
return nil, err
}
// Re-derive the original pkScript for to-self output within the
// commitment transaction. We'll need this to find the corresponding
// output in the commitment transaction and potentially for creating
// the sign descriptor.
csvTimeout := uint32(lc.localChanCfg.CsvDelay)
unusedRevocation, err := lc.channelState.RevocationProducer.AtIndex(
lc.currentHeight,
)
if err != nil {
return nil, err
}
commitPoint := ComputeCommitmentPoint(unusedRevocation[:])
keyRing := deriveCommitmentKeys(commitPoint, true, lc.localChanCfg,
lc.remoteChanCfg)
selfScript, err := commitScriptToSelf(csvTimeout, keyRing.delayKey,
keyRing.revocationKey)
if err != nil {
return nil, err
}
payToUsScriptHash, err := witnessScriptHash(selfScript)
if err != nil {
return nil, err
}
// Locate the output index of the delayed commitment output back to us.
// We'll return the details of this output to the caller so they can
// sweep it once it's mature.
var (
delayIndex uint32
delayScript []byte
selfSignDesc *SignDescriptor
)
for i, txOut := range commitTx.TxOut {
if !bytes.Equal(payToUsScriptHash, txOut.PkScript) {
continue
}
delayIndex = uint32(i)
delayScript = txOut.PkScript
break
}
// 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.
// If the output is non-existent (dust), have the sign descriptor be
// nil.
if len(delayScript) != 0 {
singleTweak := SingleTweakBytes(commitPoint,
lc.localChanCfg.DelayBasePoint)
selfSignDesc = &SignDescriptor{
PubKey: lc.localChanCfg.DelayBasePoint,
SingleTweak: singleTweak,
WitnessScript: selfScript,
Output: &wire.TxOut{
PkScript: delayScript,
Value: int64(lc.channelState.LocalBalance.ToSatoshis()),
},
HashType: txscript.SigHashAll,
}
}
// Once the delay output has been found (if it exists), then we'll also
// need to create a series of sign descriptors for any lingering
// outgoing HTLC's that we'll need to claim as well.
txHash := commitTx.TxHash()
htlcResolutions, err := extractHtlcResolutions(
lc.channelState.FeePerKw, true, lc.signer, lc.channelState.Htlcs,
keyRing, lc.localChanCfg, lc.remoteChanCfg, txHash)
if err != nil {
return nil, err
}
// Finally, close the channel force close signal which notifies any
// subscribers that the channel has now been forcibly closed. This
// allows callers to begin to carry out any post channel closure
// activities.
close(lc.ForceCloseSignal)
return &ForceCloseSummary{
ChanPoint: lc.channelState.FundingOutpoint,
SelfOutpoint: wire.OutPoint{
Hash: commitTx.TxHash(),
Index: delayIndex,
},
CloseTx: commitTx,
SelfOutputSignDesc: selfSignDesc,
SelfOutputMaturity: csvTimeout,
HtlcResolutions: htlcResolutions,
}, nil
}
// CreateCloseProposal is used by both parties in a cooperative channel close
// workflow to generate proposed close transactions and signatures. 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 is
// returned.
//
// TODO(roasbeef): caller should initiate signal to reject all incoming HTLCs,
// settle any in flight.
func (lc *LightningChannel) CreateCloseProposal(proposedFee uint64,
localDeliveryScript, remoteDeliveryScript []byte) ([]byte, uint64, error) {
lc.Lock()
defer lc.Unlock()
// If we've already closed the channel, then ignore this request.
if lc.status == channelClosed {
// TODO(roasbeef): check to ensure no pending payments
return nil, 0, ErrChanClosing
}
// Subtract the proposed fee from the appropriate balance, taking care
// not to persist the adjusted balance, as the feeRate may change
// during the channel closing process.
ourBalance := lc.channelState.LocalBalance.ToSatoshis()
theirBalance := lc.channelState.RemoteBalance.ToSatoshis()
if lc.channelState.IsInitiator {
ourBalance = ourBalance - btcutil.Amount(proposedFee)
} else {
theirBalance = theirBalance - btcutil.Amount(proposedFee)
}
closeTx := CreateCooperativeCloseTx(lc.fundingTxIn,
lc.localChanCfg.DustLimit, lc.remoteChanCfg.DustLimit,
ourBalance, theirBalance, localDeliveryScript,
remoteDeliveryScript, lc.channelState.IsInitiator)
2017-03-15 08:53:15 +03:00
// Ensure that the transaction doesn't explicitly violate any
// consensus rules such as being too big, or having any value with a
// negative output.
tx := btcutil.NewTx(closeTx)
if err := blockchain.CheckTransactionSanity(tx); err != nil {
return nil, 0, err
}
// Finally, sign the completed cooperative closure transaction. As the
// initiator we'll simply send our signature over to the remote party,
// using the generated txid to be notified once the closure transaction
// has been confirmed.
lc.signDesc.SigHashes = txscript.NewTxSigHashes(closeTx)
sig, err := lc.signer.SignOutputRaw(closeTx, lc.signDesc)
if err != nil {
return nil, 0, err
}
// As everything checks out, indicate in the channel status that a
// channel closure has been initiated.
lc.status = channelClosing
return sig, proposedFee, nil
}
// CompleteCooperativeClose completes the cooperative closure of the target
// active lightning channel. A fully signed closure transaction as well as the
// signature itself are returned.
//
// NOTE: The passed local and remote sigs are expected to be fully complete
// signatures including the proper sighash byte.
func (lc *LightningChannel) CompleteCooperativeClose(localSig, remoteSig,
localDeliveryScript, remoteDeliveryScript []byte,
proposedFee uint64) (*wire.MsgTx, error) {
lc.Lock()
defer lc.Unlock()
// If the channel is already closed, then ignore this request.
if lc.status == channelClosed {
// TODO(roasbeef): check to ensure no pending payments
return nil, ErrChanClosing
}
// Subtract the proposed fee from the appropriate balance, taking care
// not to persist the adjusted balance, as the feeRate may change
// during the channel closing process.
ourBalance := lc.channelState.LocalBalance.ToSatoshis()
theirBalance := lc.channelState.RemoteBalance.ToSatoshis()
if lc.channelState.IsInitiator {
ourBalance = ourBalance - btcutil.Amount(proposedFee)
} else {
theirBalance = theirBalance - btcutil.Amount(proposedFee)
}
// Create the transaction used to return the current settled balance
// on this active channel back to both parties. In this current model,
// the initiator pays full fees for the cooperative close transaction.
closeTx := CreateCooperativeCloseTx(lc.fundingTxIn,
lc.localChanCfg.DustLimit, lc.remoteChanCfg.DustLimit,
ourBalance, theirBalance, localDeliveryScript,
remoteDeliveryScript, lc.channelState.IsInitiator)
// Ensure that the transaction doesn't explicitly validate any
// consensus rules such as being too big, or having any value with a
// negative output.
tx := btcutil.NewTx(closeTx)
if err := blockchain.CheckTransactionSanity(tx); err != nil {
return nil, err
}
hashCache := txscript.NewTxSigHashes(closeTx)
// Finally, construct the witness stack minding the order of the
// pubkeys+sigs on the stack.
ourKey := lc.localChanCfg.MultiSigKey.SerializeCompressed()
theirKey := lc.remoteChanCfg.MultiSigKey.SerializeCompressed()
witness := SpendMultiSig(lc.signDesc.WitnessScript, ourKey,
localSig, theirKey, remoteSig)
closeTx.TxIn[0].Witness = witness
// Validate the finalized transaction to ensure the output script is
// properly met, and that the remote peer supplied a valid signature.
vm, err := txscript.NewEngine(lc.fundingP2WSH, closeTx, 0,
txscript.StandardVerifyFlags, nil, hashCache,
int64(lc.channelState.Capacity))
if err != nil {
return nil, err
}
if err := vm.Execute(); err != nil {
return nil, err
}
// As the transaction is sane, and the scripts are valid we'll mark the
// channel now as closed as the closure transaction should get into the
// chain in a timely manner and possibly be re-broadcast by the wallet.
lc.status = channelClosed
return closeTx, nil
}
// DeleteState deletes all state concerning the channel from the underlying
// database, only leaving a small summary describing metadata of the
// channel's lifetime.
func (lc *LightningChannel) DeleteState(c *channeldb.ChannelCloseSummary) error {
return lc.channelState.CloseChannel(c)
}
// StateSnapshot returns a snapshot of the current fully committed state within
// the channel.
func (lc *LightningChannel) StateSnapshot() *channeldb.ChannelSnapshot {
lc.RLock()
defer lc.RUnlock()
return lc.channelState.Snapshot()
}
// UpdateFee initiates a fee update for this channel. Must only be called by
// the channel initiator, and must be called before sending update_fee to
// the remote.
func (lc *LightningChannel) UpdateFee(feePerKw btcutil.Amount) error {
lc.Lock()
defer lc.Unlock()
// Only initiator can send fee update, so trying to send one as
// non-initiator will fail.
if !lc.channelState.IsInitiator {
return fmt.Errorf("local fee update as non-initiator")
}
lc.pendingFeeUpdate = &feePerKw
return nil
}
// ReceiveUpdateFee handles an updated fee sent from remote. This method will
// return an error if called as channel initiator.
func (lc *LightningChannel) ReceiveUpdateFee(feePerKw btcutil.Amount) error {
lc.Lock()
defer lc.Unlock()
// Only initiator can send fee update, and we must fail if we receive
// fee update as initiator
if lc.channelState.IsInitiator {
return fmt.Errorf("received fee update as initiator")
}
// TODO(halseth): should fail if fee update is unreasonable,
// as specified in BOLT#2.
lc.pendingFeeUpdate = &feePerKw
return nil
}
// CreateCommitTx creates a commitment transaction, spending from specified
// funding output. The commitment transaction contains two outputs: one paying
// to the "owner" of the commitment transaction which can be spent after a
// relative block delay or revocation event, and the other paying the
// counterparty within the channel, which can be spent immediately.
func CreateCommitTx(fundingOutput *wire.TxIn, keyRing *commitmentKeyRing,
csvTimeout uint32, amountToSelf, amountToThem, dustLimit btcutil.Amount,
) (*wire.MsgTx, error) {
// First, we create the script for the delayed "pay-to-self" output.
// This output has 2 main redemption clauses: either we can redeem the
// output after a relative block delay, or the remote node can claim
// the funds with the revocation key if we broadcast a revoked
// commitment transaction.
ourRedeemScript, err := commitScriptToSelf(csvTimeout, keyRing.delayKey,
keyRing.revocationKey)
if err != nil {
return nil, err
}
payToUsScriptHash, err := witnessScriptHash(ourRedeemScript)
if err != nil {
return nil, err
}
// Next, we create the script paying to them. This is just a regular
// P2WPKH output, without any added CSV delay.
theirWitnessKeyHash, err := commitScriptUnencumbered(keyRing.paymentKey)
if err != nil {
return nil, err
}
// Now that both output scripts have been created, we can finally create
// the transaction itself. We use a transaction version of 2 since CSV
// will fail unless the tx version is >= 2.
commitTx := wire.NewMsgTx(2)
commitTx.AddTxIn(fundingOutput)
// Avoid creating dust outputs within the commitment transaction.
if amountToSelf >= dustLimit {
commitTx.AddTxOut(&wire.TxOut{
PkScript: payToUsScriptHash,
Value: int64(amountToSelf),
})
}
if amountToThem >= dustLimit {
commitTx.AddTxOut(&wire.TxOut{
PkScript: theirWitnessKeyHash,
Value: int64(amountToThem),
})
}
return commitTx, nil
}
// CreateCooperativeCloseTx creates a transaction which if signed by both
// parties, then broadcast cooperatively closes an active channel. The creation
// of the closure transaction is modified by a boolean indicating if the party
// constructing the channel is the initiator of the closure. Currently it is
// expected that the initiator pays the transaction fees for the closing
// transaction in full.
func CreateCooperativeCloseTx(fundingTxIn *wire.TxIn,
localDust, remoteDust, ourBalance, theirBalance btcutil.Amount,
ourDeliveryScript, theirDeliveryScript []byte,
initiator bool) *wire.MsgTx {
// Construct the transaction to perform a cooperative closure of the
// channel. In the event that one side doesn't have any settled funds
// within the channel then a refund output for that particular side can
// be omitted.
closeTx := wire.NewMsgTx(2)
closeTx.AddTxIn(fundingTxIn)
// Create both cooperative closure outputs, properly respecting the
// dust limits of both parties.
if ourBalance >= localDust {
closeTx.AddTxOut(&wire.TxOut{
PkScript: ourDeliveryScript,
Value: int64(ourBalance),
})
}
if theirBalance >= remoteDust {
closeTx.AddTxOut(&wire.TxOut{
PkScript: theirDeliveryScript,
Value: int64(theirBalance),
})
}
txsort.InPlaceSort(closeTx)
return closeTx
}
// CalcFee returns the commitment fee to use for the given
// fee rate (fee-per-kw).
func (lc *LightningChannel) CalcFee(feeRate uint64) uint64 {
return (feeRate * uint64(commitWeight)) / 1000
}
// RemoteNextRevocation returns the channelState's RemoteNextRevocation.
func (lc *LightningChannel) RemoteNextRevocation() *btcec.PublicKey {
lc.Lock()
defer lc.Unlock()
return lc.channelState.RemoteNextRevocation
}
// deriveCommitmentKey generates a new commitment key set using the base points
// and commitment point. The keys are derived differently depending whether the
// commitment transaction is ours or the remote peer's.
func deriveCommitmentKeys(commitPoint *btcec.PublicKey, isOurCommit bool,
localChanCfg, remoteChanCfg *channeldb.ChannelConfig) *commitmentKeyRing {
keyRing := new(commitmentKeyRing)
keyRing.commitPoint = commitPoint
keyRing.localKeyTweak = SingleTweakBytes(commitPoint,
localChanCfg.PaymentBasePoint)
keyRing.localKey = TweakPubKeyWithTweak(localChanCfg.PaymentBasePoint,
keyRing.localKeyTweak)
keyRing.remoteKey = TweakPubKey(remoteChanCfg.PaymentBasePoint, commitPoint)
// We'll now compute the delay, payment and revocation key based on the
// current commitment point. All keys are tweaked each state in order
// to ensure the keys from each state are unlinkable. TO create the
// revocation key, we take the opposite party's revocation base point
// and combine that with the current commitment point.
var delayBasePoint, revocationBasePoint *btcec.PublicKey
if isOurCommit {
keyRing.paymentKey = keyRing.remoteKey
delayBasePoint = localChanCfg.DelayBasePoint
revocationBasePoint = remoteChanCfg.RevocationBasePoint
} else {
keyRing.paymentKey = keyRing.localKey
delayBasePoint = remoteChanCfg.DelayBasePoint
revocationBasePoint = localChanCfg.RevocationBasePoint
}
keyRing.delayKey = TweakPubKey(delayBasePoint, commitPoint)
keyRing.revocationKey = DeriveRevocationPubkey(revocationBasePoint, commitPoint)
return keyRing
}