// executeCooperativeClose executes the initial phase of a user-executed
// cooperative channel close. The channel state machine is transitioned to the
// closing phase, then our half of the closing witness is sent over to the
// remote peer.
func (p *peer) executeCooperativeClose(channel *lnwallet.LightningChannel) (*wire.ShaHash, error) {
// Shift the channel state machine into a 'closing' state. This
// generates a signature for the closing tx, as well as a txid of the
// closing tx itself, allowing us to watch the network to determine
// when the remote node broadcasts the fully signed closing
// transaction.
sig, txid, err := channel.InitCooperativeClose()
if err != nil {
return nil, err
}
chanPoint := channel.ChannelPoint()
peerLog.Infof("Executing cooperative closure of "+
"ChanPoint(%v) with peerID(%v), txid=%v", chanPoint, p.id, txid)
// With our signature for the close tx generated, send the signature to
// the remote peer instructing it to close this particular channel
// point.
// TODO(roasbeef): remove encoding redundancy
closeSig, err := btcec.ParseSignature(sig, btcec.S256())
if err != nil {
return nil, err
}
closeReq := lnwire.NewCloseRequest(chanPoint, closeSig)
p.queueMsg(closeReq, nil)
return txid, nil
}
// executeForceClose executes a unilateral close of the target channel by
// broadcasting the current commitment state directly on-chain. Once the
// commitment transaction has been broadcast, a struct describing the final
// state of the channel is sent to the utxoNursery in order to ultimatley sweep
// the immature outputs.
func (p *peer) executeForceClose(channel *lnwallet.LightningChannel) (*wire.ShaHash, error) {
// Execute a unilateral close shutting down all further channel
// operation.
closeSummary, err := channel.ForceClose()
if err != nil {
return nil, err
}
closeTx := closeSummary.CloseTx
txid := closeTx.TxSha()
// With the close transaction in hand, broadcast the transaction to the
// network, thereby entering the psot channel resolution state.
peerLog.Infof("Broadcasting force close transaction: %v",
channel.ChannelPoint(), newLogClosure(func() string {
return spew.Sdump(closeTx)
}))
if err := p.server.lnwallet.PublishTransaction(closeTx); err != nil {
return nil, err
}
// Send the closed channel summary over to the utxoNursery in order to
// have its outputs swept back into the wallet once they're mature.
p.server.utxoNursery.incubateOutputs(closeSummary)
return &txid, nil
}
// wipeChannel removes the passed channel from all indexes associated with the
// peer, and deletes the channel from the database.
func wipeChannel(p *peer, channel *lnwallet.LightningChannel) error {
chanID := channel.ChannelPoint()
delete(p.activeChannels, *chanID)
// Instruct the Htlc Switch to close this link as the channel is no
// longer active.
p.server.htlcSwitch.UnregisterLink(p.addr.IdentityKey, chanID)
htlcWireLink, ok := p.htlcManagers[*chanID]
if !ok {
return nil
}
delete(p.htlcManagers, *chanID)
close(htlcWireLink)
if err := channel.DeleteState(); err != nil {
peerLog.Errorf("Unable to delete ChannelPoint(%v) "+
"from db %v", chanID, err)
return err
}
return nil
}
// htlcManager is the primary goroutine which drives a channel's commitment
// update state-machine in response to messages received via several channels.
// The htlcManager reads messages from the upstream (remote) peer, and also
// from several possible downstream channels managed by the htlcSwitch. In the
// event that an htlc needs to be forwarded, then send-only htlcPlex chan is
// used which sends htlc packets to the switch for forwarding. Additionally,
// the htlcManager handles acting upon all timeouts for any active HTLC's,
// manages the channel's revocation window, and also the htlc trickle
// queue+timer for this active channels.
func (p *peer) htlcManager(channel *lnwallet.LightningChannel,
htlcPlex chan<- *htlcPacket, downstreamLink <-chan *htlcPacket,
upstreamLink <-chan lnwire.Message) {
chanStats := channel.StateSnapshot()
peerLog.Infof("HTLC manager for ChannelPoint(%v) started, "+
"our_balance=%v, their_balance=%v, chain_height=%v",
channel.ChannelPoint(), chanStats.LocalBalance,
chanStats.RemoteBalance, chanStats.NumUpdates)
// A new session for this active channel has just started, therefore we
// need to send our initial revocation window to the remote peer.
for i := 0; i < lnwallet.InitialRevocationWindow; i++ {
rev, err := channel.ExtendRevocationWindow()
if err != nil {
peerLog.Errorf("unable to expand revocation window: %v", err)
continue
}
p.queueMsg(rev, nil)
}
state := &commitmentState{
channel: channel,
chanPoint: channel.ChannelPoint(),
clearedHTCLs: make(map[uint32]*pendingPayment),
htlcsToSettle: make(map[uint32]*channeldb.Invoice),
pendingCircuits: make(map[uint32]*sphinx.ProcessedPacket),
sphinx: p.server.sphinx,
switchChan: htlcPlex,
}
// TODO(roasbeef): check to see if able to settle any currently pending
// HTLC's
// * also need signals when new invoices are added by the invoiceRegistry
batchTimer := time.Tick(10 * time.Millisecond)
out:
for {
select {
case <-channel.UnilateralCloseSignal:
// TODO(roasbeef): eliminate false positive via local close
peerLog.Warnf("Remote peer has closed ChannelPoint(%v) on-chain",
state.chanPoint)
if err := wipeChannel(p, channel); err != nil {
peerLog.Errorf("unable to wipe channel %v", err)
}
break out
case <-channel.ForceCloseSignal:
peerLog.Warnf("ChannelPoint(%v) has been force "+
"closed, disconnecting from peerID(%x)",
state.chanPoint, p.id)
break out
//p.Disconnect()
// TODO(roasbeef): prevent leaking ticker?
case <-state.logCommitTimer:
// If we haven't sent or received a new commitment
// update in some time, check to see if we have any
// pending updates we need to commit. If so, then send
// an update incrementing the unacked counter is
// successfully.
if !state.channel.PendingUpdates() &&
len(state.htlcsToSettle) == 0 {
continue
}
if sent, err := p.updateCommitTx(state); err != nil {
peerLog.Errorf("unable to update "+
"commitment: %v", err)
p.Disconnect()
break out
} else if sent {
state.numUnAcked += 1
}
case <-batchTimer:
// If the current batch is empty, then we have no work
// here.
if len(state.pendingBatch) == 0 {
continue
}
// Otherwise, attempt to extend the remote commitment
// chain including all the currently pending entries.
// If the send was unsuccesful, then abaondon the
// update, waiting for the revocation window to open
// up.
if sent, err := p.updateCommitTx(state); err != nil {
peerLog.Errorf("unable to update "+
"commitment: %v", err)
p.Disconnect()
break out
} else if !sent {
continue
}
state.numUnAcked += 1
case pkt := <-downstreamLink:
p.handleDownStreamPkt(state, pkt)
case msg, ok := <-upstreamLink:
// If the upstream message link is closed, this signals
// that the channel itself is being closed, therefore
// we exit.
if !ok {
break out
}
p.handleUpstreamMsg(state, msg)
case <-p.quit:
break out
}
}
p.wg.Done()
peerLog.Tracef("htlcManager for peer %v done", p)
}