akovalenko/lnd.xprv
1
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

lnwallet/channel: enumerate error cases from remote chain desync

Browse Source 
This commit enumerates the various error cases we can encounter when we
compare our remote commit chain to the view the remote communicates to us
via msg.NextLocalCommitHeight.

We now compare this height to our remote tail and tip height, returning
relevant error in case of a unrecoverable desync, and re-send a
commitment signature (including log updates) in case we owe one.
This commit is contained in:
Johan T. Halseth 2018-07-12 11:02:53 +02:00
parent f1757d6da4
commit a2f2d28d0b
No known key found for this signature in database
GPG Key ID: 15BAADA29DA20D26
1 changed files with 61 additions and 18 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

79
lnwallet/channel.go
View File

@ -10,12 +10,12 @@ import (
"sync"
"sync/atomic"
"github.com/btcsuite/btcd/blockchain"
"github.com/btcsuite/btcd/chaincfg/chainhash"
"github.com/davecgh/go-spew/spew"
"github.com/lightningnetwork/lnd/chainntnfs"
"github.com/lightningnetwork/lnd/channeldb"
"github.com/lightningnetwork/lnd/lnwire"
"github.com/btcsuite/btcd/blockchain"
"github.com/btcsuite/btcd/chaincfg/chainhash"
"github.com/btcsuite/btcd/btcec"
"github.com/btcsuite/btcd/txscript"
@ -3133,13 +3133,6 @@ func (lc *LightningChannel) ProcessChanSyncMsg(
msg *lnwire.ChannelReestablish) ([]lnwire.Message, []channeldb.CircuitKey,
[]channeldb.CircuitKey, error) {
// We owe them a commitment if they have an un-acked commitment and the
// tip of their chain (from our Pov) is equal to what they think their
// next commit height should be.
remoteChainTip := lc.remoteCommitChain.tip()
oweCommitment := (lc.remoteCommitChain.hasUnackedCommitment() &&
msg.NextLocalCommitHeight == remoteChainTip.height)
// Now we'll examine the state we have, vs what was contained in the
// chain sync message. If we're de-synchronized, then we'll send a
// batch of messages which when applied will kick start the chain
@ -3186,6 +3179,8 @@ func (lc *LightningChannel) ProcessChanSyncMsg(
// more to them.
var (
localTailHeight = lc.localCommitChain.tail().height
remoteTailHeight = lc.remoteCommitChain.tail().height
remoteTipHeight = lc.remoteCommitChain.tip().height
)
// We'll now check that their view of our local chain is up-to-date.
@ -3316,10 +3311,54 @@ func (lc *LightningChannel) ProcessChanSyncMsg(
return nil, nil, nil, ErrCannotSyncCommitChains
}
// If we owe them a commitment, then we'll read from disk our
// commitment diff, so we can re-send them to the remote party.
if oweCommitment {
// Grab the current remote chain tip from the database. This
// Now check if our view of the remote chain is consistent with what
// they tell us.
switch {
// The remote's view of what their next commit height is 2+ states
// ahead of us, we most likely lost data, or the remote is trying to
// trick us. Since we have no way of verifying whether they are lying
// or not, we will fail the channel, but should not force close it
// automatically.
case msg.NextLocalCommitHeight > remoteTipHeight+1:
walletLog.Errorf("ChannelPoint(%v), sync failed: remote's "+
"next commit height is %v, while we believe it is %v!",
lc.channelState.FundingOutpoint,
msg.NextLocalCommitHeight, remoteTipHeight)
if err := lc.channelState.MarkBorked(); err != nil {
return nil, nil, nil, err
}
return nil, nil, nil, ErrCannotSyncCommitChains
// They are waiting for a state they have already ACKed.
case msg.NextLocalCommitHeight <= remoteTailHeight:
walletLog.Errorf("ChannelPoint(%v), sync failed: remote's "+
"next commit height is %v, while we believe it is %v!",
lc.channelState.FundingOutpoint,
msg.NextLocalCommitHeight, remoteTipHeight)
// They previously ACKed our current tail, and now they are
// waiting for it. They probably lost state.
if err := lc.channelState.MarkBorked(); err != nil {
return nil, nil, nil, err
}
return nil, nil, nil, ErrCommitSyncRemoteDataLoss
// They have received our latest commitment, life is good.
case msg.NextLocalCommitHeight == remoteTipHeight+1:
// We owe them a commitment if the tip of their chain (from our Pov) is
// equal to what they think their next commit height should be. We'll
// re-send all the updates neccessary to recreate this state, along
// with the commit sig.
case msg.NextLocalCommitHeight == remoteTipHeight:
walletLog.Debugf("ChannelPoint(%v), sync: remote's next "+
"commit height is %v, while we believe it is %v, we "+
"owe them a commitment", lc.channelState.FundingOutpoint,
msg.NextLocalCommitHeight, remoteTipHeight)
// Grab the current remote chain tip from the database. This
// commit diff contains all the information required to re-sync
// our states.
commitDiff, err := lc.channelState.RemoteCommitChainTip()
@ -3341,14 +3380,18 @@ func (lc *LightningChannel) ProcessChanSyncMsg(
openedCircuits = commitDiff.OpenedCircuitKeys
closedCircuits = commitDiff.ClosedCircuitKeys
} else if remoteChainTip.height+1 != msg.NextLocalCommitHeight {
// There should be no other possible states as long as the commit chain
// can have at most two elements. If that's the case, something is
// wrong.
default:
walletLog.Errorf("ChannelPoint(%v), sync failed: remote's "+
"next commit height is %v, while we believe it is %v!",
lc.channelState.FundingOutpoint,
msg.NextLocalCommitHeight, remoteTipHeight)
if err := lc.channelState.MarkBorked(); err != nil {
return nil, nil, nil, err
}
// If we don't owe them a commitment, yet the tip of their
// chain isn't one more than the next local commit height they
// report, we'll fail the channel.
return nil, nil, nil, ErrCannotSyncCommitChains
}