lnd.xprv/peer.go
Olaoluwa Osuntokun 1b682b0f40
lnd: update server initialization due to ChainNotifier changes
This commit modifies the daemon’s initialization within the `lndMain`
method to create an instance of the current default ChainNotifier
outside of the LightningWallet.

At this point, since there are no other implementations of the
ChainNotifier, the current concrete implementation BtcdNotifier is used
by default. In the future, once other ChainNotifier implementations are
in place, config parsing should be fed into a factory function which
creates the proper ChainNotifier implementation.

Finally, several imports have been updated to reflect the change in
package name.
2016-09-01 19:13:27 -07:00

1203 lines
37 KiB
Go

package main
import (
"container/list"
"fmt"
"net"
"sync"
"sync/atomic"
"time"
"github.com/btcsuite/fastsha256"
"github.com/davecgh/go-spew/spew"
"github.com/lightningnetwork/lnd/channeldb"
"github.com/lightningnetwork/lnd/lndc"
"github.com/lightningnetwork/lnd/lnrpc"
"github.com/lightningnetwork/lnd/lnwallet"
"github.com/lightningnetwork/lnd/lnwire"
"github.com/roasbeef/btcd/btcec"
"github.com/roasbeef/btcd/txscript"
"github.com/roasbeef/btcd/wire"
"github.com/roasbeef/btcutil"
)
var (
numNodes int32
)
const (
// pingInterval is the interval at which ping messages are sent.
pingInterval = 30 * time.Second
// outgoingQueueLen is the buffer size of the channel which houses
// messages to be sent across the wire, requested by objects outside
// this struct.
outgoingQueueLen = 50
)
// outgoinMsg packages an lnwire.Message to be sent out on the wire, along with
// a buffered channel which will be sent upon once the write is complete. This
// buffered channel acts as a semaphore to be used for synchronization purposes.
type outgoinMsg struct {
msg lnwire.Message
sentChan chan struct{} // MUST be buffered.
}
// chanSnapshotReq is a message sent by outside sub-systems to a peer in order
// to gain a snapshot of the peer's currently active channels.
type chanSnapshotReq struct {
resp chan []*channeldb.ChannelSnapshot
}
// peer is an active peer on the Lightning Network. This struct is responsible
// for managing any channel state related to this peer. To do so, it has several
// helper goroutines to handle events such as HTLC timeouts, new funding
// workflow, and detecting an uncooperative closure of any active channels.
type peer struct {
// MUST be used atomically.
started int32
connected int32
disconnect int32
conn net.Conn
lightningAddr *lndc.LNAdr
lightningID wire.ShaHash
inbound bool
id int32
// For purposes of detecting retransmits, etc.
lastNMessages map[lnwire.Message]struct{}
// This mutex protects all the stats below it.
sync.RWMutex
timeConnected time.Time
lastSend time.Time
lastRecv time.Time
// The following fields are only meant to be used *atomically*
bytesReceived uint64
bytesSent uint64
satoshisSent uint64
satoshisReceived uint64
// chainNet is the Bitcoin network to which this peer is anchored to.
chainNet wire.BitcoinNet
// sendQueue is the channel which is used to queue outgoing to be
// written onto the wire. Note that this channel is unbuffered.
sendQueue chan outgoinMsg
// outgoingQueue is a buffered channel which allows second/third party
// objects to queue messages to be sent out on the wire.
outgoingQueue chan outgoinMsg
// sendQueueSync is used as a semaphore to synchronize writes between
// the writeHandler and the queueHandler.
sendQueueSync chan struct{}
// activeChannels is a map which stores the state machines of all
// active channels. Channels are indexed into the map by the txid of
// the funding transaction which opened the channel.
activeChannels map[wire.OutPoint]*lnwallet.LightningChannel
chanSnapshotReqs chan *chanSnapshotReq
htlcManagers map[wire.OutPoint]chan lnwire.Message
// newChanBarriers is a map from a channel point to a 'barrier' which
// will be signalled once the channel is fully open. This barrier acts
// as a synchronization point for any incoming/outgoing HTLCs before
// the channel has been fully opened.
barrierMtx sync.RWMutex
newChanBarriers map[wire.OutPoint]chan struct{}
barrierInits chan wire.OutPoint
// newChannels is used by the fundingManager to send fully opened
// channels to the source peer which handled the funding workflow.
newChannels chan *lnwallet.LightningChannel
// localCloseChanReqs is a channel in which any local requests to
// close a particular channel are sent over.
localCloseChanReqs chan *closeLinkReq
// remoteCloseChanReqs is a channel in which any remote requests
// (initiated by the remote peer) close a particular channel are sent
// over.
remoteCloseChanReqs chan *lnwire.CloseRequest
// nextPendingChannelID is an integer which represents the id of the
// next pending channel. Pending channels are tracked by this id
// throughout their lifetime until they become active channels, or are
// cancelled. Channels id's initiated by an outbound node start from 0,
// while channels inititaed by an inbound node start from 2^63. In
// either case, this value is always monotonically increasing.
nextPendingChannelID uint64
pendingChannelMtx sync.RWMutex
server *server
queueQuit chan struct{}
quit chan struct{}
wg sync.WaitGroup
}
// newPeer creates a new peer from an establish connection object, and a
// pointer to the main server.
func newPeer(conn net.Conn, server *server, btcNet wire.BitcoinNet, inbound bool) (*peer, error) {
lndcConn := conn.(*lndc.LNDConn)
nodePub := lndcConn.RemotePub
p := &peer{
conn: conn,
lightningID: wire.ShaHash(fastsha256.Sum256(nodePub.SerializeCompressed())),
id: atomic.AddInt32(&numNodes, 1),
chainNet: btcNet,
inbound: inbound,
server: server,
lastNMessages: make(map[lnwire.Message]struct{}),
sendQueueSync: make(chan struct{}, 1),
sendQueue: make(chan outgoinMsg, 1),
outgoingQueue: make(chan outgoinMsg, outgoingQueueLen),
barrierInits: make(chan wire.OutPoint),
newChanBarriers: make(map[wire.OutPoint]chan struct{}),
activeChannels: make(map[wire.OutPoint]*lnwallet.LightningChannel),
htlcManagers: make(map[wire.OutPoint]chan lnwire.Message),
chanSnapshotReqs: make(chan *chanSnapshotReq),
newChannels: make(chan *lnwallet.LightningChannel, 1),
localCloseChanReqs: make(chan *closeLinkReq),
remoteCloseChanReqs: make(chan *lnwire.CloseRequest),
queueQuit: make(chan struct{}),
quit: make(chan struct{}),
}
// TODO(roasbeef): re-write after lnaddr revamp, shouldn't need to use
// type assertions
var err error
tcpAddr := lndcConn.Conn.(*net.TCPConn).RemoteAddr().(*net.TCPAddr)
p.lightningAddr, err = lndc.NewLnAdr(tcpAddr, nodePub, activeNetParams.Params)
if err != nil {
return nil, err
}
// Initiate the pending channel identifier properly depending on if this
// node is inbound or outbound. This value will be used in an increasing
// manner to track pending channels.
if inbound {
p.nextPendingChannelID = 1 << 63
} else {
p.nextPendingChannelID = 0
}
// Fetch and then load all the active channels we have with this
// remote peer from the database.
activeChans, err := server.chanDB.FetchOpenChannels(&p.lightningID)
if err != nil {
peerLog.Errorf("unable to fetch active chans "+
"for peer %v: %v", p, err)
return nil, err
}
peerLog.Debugf("Loaded %v active channels from database with peerID(%v)",
len(activeChans), p.id)
if err := p.loadActiveChannels(activeChans); err != nil {
return nil, err
}
return p, nil
}
// loadActiveChannels creates indexes within the peer for tracking all active
// channels returned by the database.
func (p *peer) loadActiveChannels(chans []*channeldb.OpenChannel) error {
for _, dbChan := range chans {
chanID := dbChan.ChanID
lnChan, err := lnwallet.NewLightningChannel(p.server.lnwallet,
p.server.chainNotifier, p.server.chanDB, dbChan)
if err != nil {
return err
}
chanPoint := wire.OutPoint{
Hash: chanID.Hash,
Index: chanID.Index,
}
p.activeChannels[chanPoint] = lnChan
peerLog.Infof("peerID(%v) loaded ChannelPoint(%v)", p.id, chanPoint)
// Register this new channel link with the HTLC Switch. This is
// necessary to properly route multi-hop payments, and forward
// new payments triggered by RPC clients.
downstreamLink := make(chan *htlcPacket, 10)
plexChan := p.server.htlcSwitch.RegisterLink(p,
dbChan.Snapshot(), downstreamLink)
upstreamLink := make(chan lnwire.Message, 10)
p.htlcManagers[chanPoint] = upstreamLink
p.wg.Add(1)
go p.htlcManager(lnChan, plexChan, downstreamLink, upstreamLink)
}
return nil
}
// Start starts all helper goroutines the peer needs for normal operations.
// In the case this peer has already beeen started, then this function is a
// noop.
func (p *peer) Start() error {
if atomic.AddInt32(&p.started, 1) != 1 {
return nil
}
peerLog.Tracef("peer %v starting", p)
p.wg.Add(4)
go p.readHandler()
go p.queueHandler()
go p.writeHandler()
go p.channelManager()
return nil
}
// Stop signals the peer for a graceful shutdown. All active goroutines will be
// signaled to wrap up any final actions. This function will also block until
// all goroutines have exited.
func (p *peer) Stop() error {
// If we're already disconnecting, just exit.
if atomic.AddInt32(&p.disconnect, 1) != 1 {
return nil
}
// Otherwise, close the connection if we're currently connected.
if atomic.LoadInt32(&p.connected) != 0 {
p.conn.Close()
}
// Signal all worker goroutines to gracefully exit.
close(p.quit)
p.wg.Wait()
return nil
}
// Disconnect terminates the connection with the remote peer. Additionally, a
// signal is sent to the server and htlcSwitch indicating the resources
// allocated to the peer can now be cleaned up.
func (p *peer) Disconnect() {
if !atomic.CompareAndSwapInt32(&p.disconnect, 0, 1) {
return
}
peerLog.Tracef("Disconnecting %s", p)
if atomic.LoadInt32(&p.connected) != 0 {
p.conn.Close()
}
close(p.quit)
// Launch a goroutine to clean up the remaining resources.
go func() {
// Tell the switch to unregister all links associated with this
// peer. Passing nil as the target link indicates that all links
// associated with this interface should be closed.
p.server.htlcSwitch.UnregisterLink(p.lightningID, nil)
p.server.donePeers <- p
}()
}
// String returns the string representation of this peer.
func (p *peer) String() string {
return p.conn.RemoteAddr().String()
}
// readNextMessage reads, and returns the next message on the wire along with
// any additional raw payload.
func (p *peer) readNextMessage() (lnwire.Message, []byte, error) {
// TODO(roasbeef): use our own net magic?
n, nextMsg, rawPayload, err := lnwire.ReadMessage(p.conn, 0, p.chainNet)
atomic.AddUint64(&p.bytesReceived, uint64(n))
if err != nil {
return nil, nil, err
}
// TODO(roasbeef): add message summaries
peerLog.Tracef("readMessage from %v: %v", p, newLogClosure(func() string {
return spew.Sdump(nextMsg)
}))
return nextMsg, rawPayload, nil
}
// readHandler is responsible for reading messages off the wire in series, then
// properly dispatching the handling of the message to the proper sub-system.
//
// NOTE: This method MUST be run as a goroutine.
func (p *peer) readHandler() {
out:
for atomic.LoadInt32(&p.disconnect) == 0 {
nextMsg, _, err := p.readNextMessage()
if err != nil {
peerLog.Infof("unable to read message: %v", err)
break out
}
var isChanUpate bool
var targetChan *wire.OutPoint
switch msg := nextMsg.(type) {
// TODO(roasbeef): consolidate into predicate (single vs dual)
case *lnwire.SingleFundingRequest:
p.server.fundingMgr.processFundingRequest(msg, p)
case *lnwire.SingleFundingResponse:
p.server.fundingMgr.processFundingResponse(msg, p)
case *lnwire.SingleFundingComplete:
p.server.fundingMgr.processFundingComplete(msg, p)
case *lnwire.SingleFundingSignComplete:
p.server.fundingMgr.processFundingSignComplete(msg, p)
case *lnwire.SingleFundingOpenProof:
p.server.fundingMgr.processFundingOpenProof(msg, p)
case *lnwire.CloseRequest:
p.remoteCloseChanReqs <- msg
// TODO(roasbeef): interface for htlc update msgs
// * .(CommitmentUpdater)
case *lnwire.HTLCAddRequest:
isChanUpate = true
targetChan = msg.ChannelPoint
case *lnwire.HTLCSettleRequest:
isChanUpate = true
targetChan = msg.ChannelPoint
case *lnwire.CommitRevocation:
isChanUpate = true
targetChan = msg.ChannelPoint
case *lnwire.CommitSignature:
isChanUpate = true
targetChan = msg.ChannelPoint
case *lnwire.NeighborAckMessage,
*lnwire.NeighborHelloMessage,
*lnwire.NeighborRstMessage,
*lnwire.NeighborUpdMessage,
*lnwire.RoutingTableRequestMessage,
*lnwire.RoutingTableTransferMessage:
// TODO(mkl): determine sender and receiver of message
p.server.routingMgr.ChIn <- msg
}
if isChanUpate {
// We might be receiving an update to a newly funded
// channel in which we were the responder. Therefore
// we need to possibly block until the new channel has
// propagated internally through the system.
p.barrierMtx.RLock()
barrier, ok := p.newChanBarriers[*targetChan]
p.barrierMtx.RUnlock()
if ok {
peerLog.Tracef("waiting for chan barrier "+
"signal for ChannelPoint(%v)", targetChan)
select {
case <-barrier:
case <-p.quit: // TODO(roasbeef): add timer?
break out
}
peerLog.Tracef("barrier for ChannelPoint(%v) "+
"closed", targetChan)
}
// Dispatch the commitment update message to the proper
// active goroutine dedicated to this channel.
targetChan, ok := p.htlcManagers[*targetChan]
if !ok {
peerLog.Errorf("recv'd update for unknown channel %v",
targetChan)
continue
}
targetChan <- nextMsg
}
}
p.Disconnect()
p.wg.Done()
peerLog.Tracef("readHandler for peer %v done", p)
}
// writeMessage writes the target lnwire.Message to the remote peer.
func (p *peer) writeMessage(msg lnwire.Message) error {
// Simply exit if we're shutting down.
if atomic.LoadInt32(&p.disconnect) != 0 {
return nil
}
// TODO(roasbeef): add message summaries
peerLog.Tracef("writeMessage to %v: %v", p, newLogClosure(func() string {
return spew.Sdump(msg)
}))
n, err := lnwire.WriteMessage(p.conn, msg, 0, p.chainNet)
atomic.AddUint64(&p.bytesSent, uint64(n))
return err
}
// writeHandler is a goroutine dedicated to reading messages off of an incoming
// queue, and writing them out to the wire. This goroutine coordinates with the
// queueHandler in order to ensure the incoming message queue is quickly drained.
//
// NOTE: This method MUST be run as a goroutine.
func (p *peer) writeHandler() {
// pingTicker is used to periodically send pings to the remote peer.
pingTicker := time.NewTicker(pingInterval)
defer pingTicker.Stop()
out:
for {
select {
case outMsg := <-p.sendQueue:
switch m := outMsg.msg.(type) {
// TODO(roasbeef): handle special write cases
}
if err := p.writeMessage(outMsg.msg); err != nil {
peerLog.Errorf("unable to write message: %v", err)
p.Disconnect()
break out
}
// Synchronize with the writeHandler.
p.sendQueueSync <- struct{}{}
case <-pingTicker.C:
// TODO(roasbeef): move ping to time.AfterFunc
case <-p.quit:
break out
}
}
// Wait for the queueHandler to finish so we can empty out all pending
// messages avoiding a possible deadlock somewhere.
<-p.queueQuit
// Drain any lingering messages that we're meant to be sent. But since
// we're shutting down, just ignore them.
fin:
for {
select {
case msg := <-p.sendQueue:
if msg.sentChan != nil {
msg.sentChan <- struct{}{}
}
default:
break fin
}
}
p.wg.Done()
peerLog.Tracef("writeHandler for peer %v done", p)
}
// queueHandler is responsible for accepting messages from outside sub-systems
// to be eventually sent out on the wire by the writeHandler.
//
// NOTE: This method MUST be run as a goroutine.
func (p *peer) queueHandler() {
waitOnSync := false
pendingMsgs := list.New()
out:
for {
select {
case msg := <-p.outgoingQueue:
if !waitOnSync {
p.sendQueue <- msg
} else {
pendingMsgs.PushBack(msg)
}
waitOnSync = true
case <-p.sendQueueSync:
// If there aren't any more remaining messages in the
// queue, then we're no longer waiting to synchronize
// with the writeHandler.
next := pendingMsgs.Front()
if next == nil {
waitOnSync = false
continue
}
// Notify the writeHandler about the next item to
// asynchronously send.
val := pendingMsgs.Remove(next)
p.sendQueue <- val.(outgoinMsg)
// TODO(roasbeef): other sync stuffs
case <-p.quit:
break out
}
}
close(p.queueQuit)
p.wg.Done()
}
// queueMsg queues a new lnwire.Message to be eventually sent out on the
// wire.
func (p *peer) queueMsg(msg lnwire.Message, doneChan chan struct{}) {
p.outgoingQueue <- outgoinMsg{msg, doneChan}
}
// ChannelSnapshots returns a slice of channel snapshots detaling all currently
// active channels maintained with the remote peer.
func (p *peer) ChannelSnapshots() []*channeldb.ChannelSnapshot {
resp := make(chan []*channeldb.ChannelSnapshot, 1)
p.chanSnapshotReqs <- &chanSnapshotReq{resp}
return <-resp
}
// channelManager is goroutine dedicated to handling all requests/signals
// pertaining to the opening, cooperative closing, and force closing of all
// channels maintained with the remote peer.
//
// NOTE: This method MUST be run as a goroutine.
func (p *peer) channelManager() {
out:
for {
select {
case req := <-p.chanSnapshotReqs:
snapshots := make([]*channeldb.ChannelSnapshot, 0, len(p.activeChannels))
for _, activeChan := range p.activeChannels {
snapshot := activeChan.StateSnapshot()
snapshots = append(snapshots, snapshot)
}
req.resp <- snapshots
case pendingChanPoint := <-p.barrierInits:
p.barrierMtx.Lock()
peerLog.Tracef("Creating chan barrier for "+
"ChannelPoint(%v)", pendingChanPoint)
p.newChanBarriers[pendingChanPoint] = make(chan struct{})
p.barrierMtx.Unlock()
case newChan := <-p.newChannels:
chanPoint := *newChan.ChannelPoint()
p.activeChannels[chanPoint] = newChan
peerLog.Infof("New channel active ChannelPoint(%v) "+
"with peerId(%v)", chanPoint, p.id)
// Now that the channel is open, notify the Htlc
// Switch of a new active link.
chanSnapShot := newChan.StateSnapshot()
downstreamLink := make(chan *htlcPacket, 10)
plexChan := p.server.htlcSwitch.RegisterLink(p,
chanSnapShot, downstreamLink)
// With the channel registered to the HtlcSwitch spawn
// a goroutine to handle commitment updates for this
// new channel.
upstreamLink := make(chan lnwire.Message, 10)
p.htlcManagers[chanPoint] = upstreamLink
p.wg.Add(1)
go p.htlcManager(newChan, plexChan, downstreamLink, upstreamLink)
// Close the active channel barrier signalling the
// readHandler that commitment related modifications to
// this channel can now proceed.
p.barrierMtx.Lock()
peerLog.Tracef("Closing chan barrier for ChannelPoint(%v)", chanPoint)
close(p.newChanBarriers[chanPoint])
delete(p.newChanBarriers, chanPoint)
p.barrierMtx.Unlock()
case req := <-p.localCloseChanReqs:
p.handleLocalClose(req)
case req := <-p.remoteCloseChanReqs:
p.handleRemoteClose(req)
case <-p.quit:
break out
}
}
p.wg.Done()
}
// handleLocalClose kicks-off the workflow to execute a cooperative closure of
// the channel initiated by a local sub-system.
func (p *peer) handleLocalClose(req *closeLinkReq) {
chanPoint := req.chanPoint
key := wire.OutPoint{
Hash: chanPoint.Hash,
Index: chanPoint.Index,
}
channel := p.activeChannels[key]
// 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 {
req.err <- err
return
}
peerLog.Infof("Executing cooperative closure of "+
"ChanPoint(%v) with peerID(%v), txid=%v", key, 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 {
req.err <- err
return
}
closeReq := lnwire.NewCloseRequest(chanPoint, closeSig)
p.queueMsg(closeReq, nil)
// Update the caller w.r.t the current pending state of this request.
req.updates <- &lnrpc.CloseStatusUpdate{
Update: &lnrpc.CloseStatusUpdate_ClosePending{
ClosePending: &lnrpc.PendingUpdate{
Txid: txid[:],
},
},
}
// Finally, launch a goroutine which will request to be notified by the
// ChainNotifier once the closure transaction obtains a single
// confirmation.
go func() {
// TODO(roasbeef): add param for num needed confs
confNtfn, err := p.server.chainNotifier.RegisterConfirmationsNtfn(txid, 1)
if err != nil {
req.err <- err
return
}
select {
case height, ok := <-confNtfn.Confirmed:
// In the case that the ChainNotifier is shutting
// down, all subscriber notification channels will be
// closed, generating a nil receive.
if !ok {
// TODO(roasbeef): check for nil elsewhere
return
}
// The channel has been closed, remove it from any
// active indexes, and the database state.
peerLog.Infof("ChannelPoint(%v) is now "+
"closed at height %v", key, height)
if err := wipeChannel(p, channel); err != nil {
req.err <- err
return
}
case <-p.quit:
return
}
// Respond to the local sub-system which requested the channel
// closure.
req.updates <- &lnrpc.CloseStatusUpdate{
Update: &lnrpc.CloseStatusUpdate_ChanClose{
ChanClose: &lnrpc.ChannelCloseUpdate{
ClosingTxid: txid[:],
Success: true,
},
},
}
}()
}
// handleRemoteClose completes a request for cooperative channel closure
// initiated by the remote node.
func (p *peer) handleRemoteClose(req *lnwire.CloseRequest) {
chanPoint := req.ChannelPoint
key := wire.OutPoint{
Hash: chanPoint.Hash,
Index: chanPoint.Index,
}
channel := p.activeChannels[key]
// Now that we have their signature for the closure transaction, we
// can assemble the final closure transaction, complete with our
// signature.
sig := req.RequesterCloseSig
closeSig := append(sig.Serialize(), byte(txscript.SigHashAll))
closeTx, err := channel.CompleteCooperativeClose(closeSig)
if err != nil {
peerLog.Errorf("unable to complete cooperative "+
"close for ChannelPoint(%v): %v",
chanPoint, err)
// TODO(roasbeef): send ErrorGeneric to other side
return
}
// Finally, broadcast the closure transaction, to the network.
peerLog.Infof("Broadcasting cooperative close tx: %v", newLogClosure(func() string {
return spew.Sdump(closeTx)
}))
if err := p.server.lnwallet.PublishTransaction(closeTx); err != nil {
peerLog.Errorf("channel close tx from "+
"ChannelPoint(%v) rejected: %v",
chanPoint, err)
// TODO(roasbeef): send ErrorGeneric to other side
return
}
// TODO(roasbeef): also wait for confs before removing state
peerLog.Infof("ChannelPoint(%v) is now "+
"closed", key)
wipeChannel(p, channel)
}
// 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.lightningID, chanID)
htlcWireLink := p.htlcManagers[*chanID]
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
}
// pendingPayment represents a pending HTLC which has yet to be settled by the
// upstream peer. A pending payment encapsulates the initial HTLC add request
// additionally coupling the index of the HTLC within the log, and an error
// channel to signal the payment requester once the payment has been fully
// fufilled.
type pendingPayment struct {
htlc *lnwire.HTLCAddRequest
index uint32
err chan error
}
// commitmentState is the volatile+persistent state of an active channel's
// commitment update state-machine. This struct is used by htlcManager's to
// save meta-state required for proper functioning.
type commitmentState struct {
// htlcsToSettle is a list of preimages which allow us to settle one or
// many of the pending HTLC's we've received from the upstream peer.
htlcsToSettle map[uint32]invoice
// TODO(roasbeef): use once trickle+batch logic is in
pendingBatch []*pendingPayment
// clearedHTCLs is a map of outgoing HTLC's we've committed to in our
// chain which have not yet been settled by the upstream peer.
clearedHTCLs map[uint32]*pendingPayment
// numUnAcked is a counter tracking the number of unacked changes we've
// sent. A change is acked once we receive a new update to our local
// chain from the remote peer.
numUnAcked uint32
// logCommitTimer is a timer which is sent upon if we go an interval
// without receiving/sending a commitment update. It's role is to
// ensure both chains converge to identical state in a timely manner.
// TODO(roasbeef): timer should be >> then RTT
logCommitTimer <-chan time.Time
// switchChan is a channel used to send packets to the htlc switch for
// fowarding.
switchChan chan<- *htlcPacket
channel *lnwallet.LightningChannel
chanPoint *wire.OutPoint
}
// 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]invoice),
switchChan: htlcPlex,
}
batchTimer := time.Tick(10 * time.Millisecond)
out:
for {
select {
// 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 coutner is
// succesful.
if !state.channel.PendingUpdates() {
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)
}
// handleDownStreamPkt processes an HTLC packet sent from the downstream HTLC
// Switch. Possible messages sent by the switch include requests to forward new
// HTLC's, timeout previously cleared HTLC's, and finally to settle currently
// cleared HTLC's with the upstream peer.
func (p *peer) handleDownStreamPkt(state *commitmentState, pkt *htlcPacket) {
switch htlc := pkt.msg.(type) {
case *lnwire.HTLCAddRequest:
// A new payment has been initiated via the
// downstream channel, so we add the new HTLC
// to our local log, then update the commitment
// chains.
index := state.channel.AddHTLC(htlc)
p.queueMsg(htlc, nil)
state.pendingBatch = append(state.pendingBatch, &pendingPayment{
htlc: htlc,
index: index,
err: pkt.err,
})
// If this newly added update exceeds the max batch size, the
// initiate an update.
// TODO(roasbeef): enforce max HTLC's in flight limit
if len(state.pendingBatch) >= 10 {
if sent, err := p.updateCommitTx(state); err != nil {
peerLog.Errorf("unable to update "+
"commitment: %v", err)
p.Disconnect()
return
} else if !sent {
return
}
state.numUnAcked += 1
}
}
}
// handleUpstreamMsg processes wire messages related to commitment state
// updates from the upstream peer. The upstream peer is the peer whom we have a
// direct channel with, updating our respective commitment chains.
func (p *peer) handleUpstreamMsg(state *commitmentState, msg lnwire.Message) {
switch htlcPkt := msg.(type) {
// TODO(roasbeef): timeouts
// * fail if can't parse sphinx mix-header
case *lnwire.HTLCAddRequest:
// We just received an add request from an upstream peer, so we
// add it to our state machine, then add the HTLC to our
// "settle" list in the event that we know the pre-image
index := state.channel.ReceiveHTLC(htlcPkt)
rHash := htlcPkt.RedemptionHashes[0]
if invoice, found := p.server.invoices.lookupInvoice(rHash); found {
// TODO(roasbeef): check value
// * onion layer strip should also be before invoice lookup
// * also can immediately send the settle msg
invCopy := *invoice
invCopy.value = btcutil.Amount(htlcPkt.Amount)
state.htlcsToSettle[index] = invCopy
}
case *lnwire.HTLCSettleRequest:
// TODO(roasbeef): this assumes no "multi-sig"
pre := htlcPkt.RedemptionProofs[0]
idx := uint32(htlcPkt.HTLCKey)
if err := state.channel.ReceiveHTLCSettle(pre, idx); err != nil {
// TODO(roasbeef): broadcast on-chain
peerLog.Errorf("settle for outgoing HTLC rejected: %v", err)
p.Disconnect()
return
}
case *lnwire.CommitSignature:
// We just received a new update to our local commitment chain,
// validate this new commitment, closing the link if invalid.
// TODO(roasbeef): use uint64 for indexes?
logIndex := uint32(htlcPkt.LogIndex)
sig := htlcPkt.CommitSig.Serialize()
if err := state.channel.ReceiveNewCommitment(sig, logIndex); err != nil {
peerLog.Errorf("unable to accept new commitment: %v", err)
p.Disconnect()
return
}
if state.numUnAcked > 0 {
state.numUnAcked -= 1
// TODO(roasbeef): only start if numUnacked == 0?
state.logCommitTimer = time.Tick(300 * time.Millisecond)
} else {
if _, err := p.updateCommitTx(state); err != nil {
peerLog.Errorf("unable to update "+
"commitment: %v", err)
p.Disconnect()
return
}
}
// Finally, since we just accepted a new state, send the remote
// peer a revocation for our prior state.
nextRevocation, err := state.channel.RevokeCurrentCommitment()
if err != nil {
peerLog.Errorf("unable to revoke current commitment: %v", err)
return
}
p.queueMsg(nextRevocation, nil)
case *lnwire.CommitRevocation:
// We've received a revocation from the remote chain, if valid,
// this moves the remote chain forward, and expands our
// revocation window.
htlcsToForward, err := state.channel.ReceiveRevocation(htlcPkt)
if err != nil {
peerLog.Errorf("unable to accept revocation: %v", err)
p.Disconnect()
return
}
// We perform the HTLC forwarding to the switch in a distinct
// goroutine in order not to block the post-processing of
// HTLC's that are eligble for forwarding.
// TODO(roasbeef): no need to forward if have settled any of
// these.
go func() {
for _, htlc := range htlcsToForward {
// Send this fully activated HTLC to the htlc
// switch to continue the chained clear/settle.
state.switchChan <- p.logEntryToHtlcPkt(htlc)
}
}()
// If any of the htlc's eligible for forwarding are pending
// settling or timeing out previous outgoing payments, then we
// can them from the pending set, and signal the requster (if
// existing) that the payment has been fully fulfilled.
var bandwidthUpdate btcutil.Amount
numSettled := 0
for _, htlc := range htlcsToForward {
if p, ok := state.clearedHTCLs[htlc.ParentIndex]; ok {
p.err <- nil
delete(state.clearedHTCLs, htlc.ParentIndex)
}
// TODO(roasbeef): rework log entries to a shared
// interface.
if htlc.EntryType != lnwallet.Add {
continue
}
// If we can't immediately settle this HTLC, then we
// can halt processing here.
invoice, ok := state.htlcsToSettle[htlc.Index]
if !ok {
continue
}
// Otherwise, we settle this HTLC within our local
// state update log, then send the update entry to the
// remote party.
logIndex, err := state.channel.SettleHTLC(invoice.paymentPreimage)
if err != nil {
peerLog.Errorf("unable to settle htlc: %v", err)
p.Disconnect()
continue
}
settleMsg := &lnwire.HTLCSettleRequest{
ChannelPoint: state.chanPoint,
HTLCKey: lnwire.HTLCKey(logIndex),
RedemptionProofs: [][32]byte{invoice.paymentPreimage},
}
p.queueMsg(settleMsg, nil)
delete(state.htlcsToSettle, htlc.Index)
bandwidthUpdate += invoice.value
numSettled++
}
if numSettled == 0 {
return
}
// Send an update to the htlc switch of our newly available
// payment bandwidth.
// TODO(roasbeef): ideally should wait for next state update.
if bandwidthUpdate != 0 {
p.server.htlcSwitch.UpdateLink(state.chanPoint,
bandwidthUpdate)
}
// With all the settle updates added to the local and remote
// HTLC logs, initiate a state transition by updating the
// remote commitment chain.
if sent, err := p.updateCommitTx(state); err != nil {
peerLog.Errorf("unable to update commitment: %v", err)
p.Disconnect()
return
} else if sent {
// TODO(roasbeef): wait to delete from htlcsToSettle?
state.numUnAcked += 1
}
}
}
// updateCommitTx signs, then sends an update to the remote peer adding a new
// commitment to their commitment chain which includes all the latest updates
// we've received+processed up to this point.
func (p *peer) updateCommitTx(state *commitmentState) (bool, error) {
sigTheirs, logIndexTheirs, err := state.channel.SignNextCommitment()
if err == lnwallet.ErrNoWindow {
peerLog.Tracef("revocation window exhausted, unable to send %v",
len(state.pendingBatch))
return false, nil
} else if err != nil {
return false, err
}
parsedSig, err := btcec.ParseSignature(sigTheirs, btcec.S256())
if err != nil {
return false, fmt.Errorf("unable to parse sig: %v", err)
}
commitSig := &lnwire.CommitSignature{
ChannelPoint: state.chanPoint,
CommitSig: parsedSig,
LogIndex: uint64(logIndexTheirs),
}
p.queueMsg(commitSig, nil)
// Move all pending updates to the map of cleared HTLC's, clearing out
// the set of pending updates.
for _, update := range state.pendingBatch {
// TODO(roasbeef): add parsed next-hop info to pending batch
// for multi-hop forwarding
state.clearedHTCLs[update.index] = update
}
state.logCommitTimer = nil
state.pendingBatch = nil
return true, nil
}
// logEntryToHtlcPkt converts a particular Lightning Commitment Protocol (LCP)
// log entry the corresponding htlcPacket with src/dest set along with the
// proper wire message. This helepr method is provided in order to aide an
// htlcManager in forwarding packets to the htlcSwitch.
func (p *peer) logEntryToHtlcPkt(pd *lnwallet.PaymentDescriptor) *htlcPacket {
pkt := &htlcPacket{}
// TODO(roasbeef): alter after switch to log entry interface
var msg lnwire.Message
switch pd.EntryType {
case lnwallet.Add:
// TODO(roasbeef): timeout, onion blob, etc
msg = &lnwire.HTLCAddRequest{
Amount: lnwire.CreditsAmount(pd.Amount),
RedemptionHashes: [][32]byte{pd.RHash},
}
case lnwallet.Settle:
// TODO(roasbeef): thread through preimage
msg = &lnwire.HTLCSettleRequest{
HTLCKey: lnwire.HTLCKey(pd.ParentIndex),
}
}
// TODO(roasbeef): set dest via onion blob or state
pkt.amt = pd.Amount
pkt.msg = msg
pkt.src = p.lightningID
return pkt
}
// TODO(roasbeef): make all start/stop mutexes a CAS