From 8e77e1e6eb788fd1ef53f5cd215b14e5f34827a4 Mon Sep 17 00:00:00 2001 From: "Johan T. Halseth" Date: Mon, 19 Mar 2018 15:19:19 +0100 Subject: [PATCH] lnwallet/channel: add NewLocalForceCloseSummary This commit renames ForceCloseSummary to LocalForceCloseSummary, and adds a new method NewLocalForceCloseSummary that can be used to derive a LocalForceCloseSummary if our commitment transaction gets confirmed in-chain. It is meant to accompany the NewUnilateralCloseSummary method, which is used for the same purpose in the event of a remote commitment being seen in-chain. --- contractcourt/chain_arbitrator.go | 2 +- contractcourt/channel_arbitrator.go | 2 +- lnwallet/channel.go | 90 +++++++++++++++++------------ 3 files changed, 55 insertions(+), 39 deletions(-) diff --git a/contractcourt/chain_arbitrator.go b/contractcourt/chain_arbitrator.go index 03be99c09..ffd0cc769 100644 --- a/contractcourt/chain_arbitrator.go +++ b/contractcourt/chain_arbitrator.go @@ -196,7 +196,7 @@ func newActiveChannelArbitrator(channel *channeldb.OpenChannel, ChanPoint: chanPoint, ShortChanID: channel.ShortChanID, BlockEpochs: blockEpoch, - ForceCloseChan: func() (*lnwallet.ForceCloseSummary, error) { + ForceCloseChan: func() (*lnwallet.LocalForceCloseSummary, error) { // With the channels fetched, attempt to locate // the target channel according to its channel // point. diff --git a/contractcourt/channel_arbitrator.go b/contractcourt/channel_arbitrator.go index 83792ddb9..58c5c2113 100644 --- a/contractcourt/channel_arbitrator.go +++ b/contractcourt/channel_arbitrator.go @@ -89,7 +89,7 @@ type ChannelArbitratorConfig struct { // is watching over. We'll use this when we decide that we need to go // to chain. The returned summary contains all items needed to // eventually resolve all outputs on chain. - ForceCloseChan func() (*lnwallet.ForceCloseSummary, error) + ForceCloseChan func() (*lnwallet.LocalForceCloseSummary, error) // CloseChannel is a function closure that marks a channel under watch // as "closing". In this phase, we will no longer accept any updates to diff --git a/lnwallet/channel.go b/lnwallet/channel.go index 962bc8677..28367dfa8 100644 --- a/lnwallet/channel.go +++ b/lnwallet/channel.go @@ -5203,23 +5203,24 @@ func extractHtlcResolutions(feePerKw SatPerKWeight, ourCommit bool, }, 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 { +// LocalForceCloseSummary describes the final commitment state before the +// channel is locked-down to initiate a force closure by broadcasting the +// latest state on-chain. If we intend to broadcast this this state, the +// channel should not be used after generating this close summary. The summary +// includes all the information required to claim all rightfully owned outputs +// when the commitment gets confirmed. +type LocalForceCloseSummary struct { // ChanPoint is the outpoint that created the channel which has been // force closed. ChanPoint wire.OutPoint - // CloseTx is the transaction which closed the channel on-chain. If we - // initiate the force close, then this will be our latest commitment - // state. Otherwise, this will be the state that the remote peer - // broadcasted on-chain. + // CloseTx is the transaction which can be used to close the channel + // on-chain. When we initiate a force close, this will be our latest + // commitment state. CloseTx *wire.MsgTx // CommitResolution contains all the data required to sweep the output - // to ourselves. If this is our commitment transaction, then we'll need + // to ourselves. Since this is our commitment transaction, we'll need // to wait a time delay before we can sweep the output. // // NOTE: If our commitment delivery output is below the dust limit, @@ -5227,52 +5228,69 @@ type ForceCloseSummary struct { CommitResolution *CommitOutputResolution // HtlcResolutions contains all the data required to sweep any outgoing - // HTLC's and incoming HTLc's we now the preimage to. For each of these + // HTLC's and incoming HTLc's we know the preimage to. For each of these // HTLC's, we'll need to go to the second level to sweep them fully. HtlcResolutions *HtlcResolutions // ChanSnapshot is a snapshot of the final state of the channel at the - // time it was closed. + // time the summary was created. ChanSnapshot channeldb.ChannelSnapshot } // 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. +// rejected. Additionally, this function also returns a LocalForceCloseSummary +// which includes the necessary details required to sweep all the time-locked +// outputs 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) { +func (lc *LightningChannel) ForceClose() (*LocalForceCloseSummary, 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 } + localCommitment := lc.channelState.LocalCommitment + summary, err := NewLocalForceCloseSummary(lc.channelState, + lc.signer, lc.pCache, commitTx, localCommitment) + if err != nil { + return nil, err + } + + // Set the channel state to indicate that the channel is now in a + // contested state. + lc.status = channelDispute + + return summary, nil +} + +// NewLocalForceCloseSummary generates a LocalForceCloseSummary from the given +// channel state. The passed commitTx must be a fully signed commitment +// transaction corresponding to localCommit. +func NewLocalForceCloseSummary(chanState *channeldb.OpenChannel, signer Signer, + pCache PreimageCache, commitTx *wire.MsgTx, + localCommit channeldb.ChannelCommitment) (*LocalForceCloseSummary, error) { + // 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, + csvTimeout := uint32(chanState.LocalChanCfg.CsvDelay) + revocation, err := chanState.RevocationProducer.AtIndex( + localCommit.CommitHeight, ) if err != nil { return nil, err } - commitPoint := ComputeCommitmentPoint(unusedRevocation[:]) - keyRing := deriveCommitmentKeys(commitPoint, true, lc.localChanCfg, - lc.remoteChanCfg) + commitPoint := ComputeCommitmentPoint(revocation[:]) + keyRing := deriveCommitmentKeys(commitPoint, true, &chanState.LocalChanCfg, + &chanState.RemoteChanCfg) selfScript, err := commitScriptToSelf(csvTimeout, keyRing.DelayKey, keyRing.RevocationKey) if err != nil { @@ -5300,8 +5318,6 @@ func (lc *LightningChannel) ForceClose() (*ForceCloseSummary, error) { break } - localCommitment := lc.channelState.LocalCommitment - // 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 @@ -5311,16 +5327,16 @@ func (lc *LightningChannel) ForceClose() (*ForceCloseSummary, error) { var commitResolution *CommitOutputResolution if len(delayScript) != 0 { singleTweak := SingleTweakBytes( - commitPoint, lc.localChanCfg.DelayBasePoint.PubKey, + commitPoint, chanState.LocalChanCfg.DelayBasePoint.PubKey, ) - localBalance := localCommitment.LocalBalance + localBalance := localCommit.LocalBalance commitResolution = &CommitOutputResolution{ SelfOutPoint: wire.OutPoint{ Hash: commitTx.TxHash(), Index: delayIndex, }, SelfOutputSignDesc: SignDescriptor{ - KeyDesc: lc.localChanCfg.DelayBasePoint, + KeyDesc: chanState.LocalChanCfg.DelayBasePoint, SingleTweak: singleTweak, WitnessScript: selfScript, Output: &wire.TxOut{ @@ -5338,19 +5354,19 @@ func (lc *LightningChannel) ForceClose() (*ForceCloseSummary, error) { // outgoing HTLC's that we'll need to claim as well. txHash := commitTx.TxHash() htlcResolutions, err := extractHtlcResolutions( - SatPerKWeight(localCommitment.FeePerKw), true, lc.signer, - localCommitment.Htlcs, keyRing, lc.localChanCfg, - lc.remoteChanCfg, txHash, lc.pCache) + SatPerKWeight(localCommit.FeePerKw), true, signer, + localCommit.Htlcs, keyRing, &chanState.LocalChanCfg, + &chanState.RemoteChanCfg, txHash, pCache) if err != nil { return nil, err } - return &ForceCloseSummary{ - ChanPoint: lc.channelState.FundingOutpoint, + return &LocalForceCloseSummary{ + ChanPoint: chanState.FundingOutpoint, CloseTx: commitTx, CommitResolution: commitResolution, HtlcResolutions: htlcResolutions, - ChanSnapshot: *lc.channelState.Snapshot(), + ChanSnapshot: *chanState.Snapshot(), }, nil }