lnd.xprv/peer.go
Olaoluwa Osuntokun 65dede2584
peer: ensure chan sends to breachArbiter can't block indefinitely
This commit fixes a possible deadlock bug that may arise during
shutdown due to an unconditional send on a channel to the breach
arbiter. We do this on two occasions within the peer: when loading a
new contract to give it the live version, and also when closing a
channel to ensure that it no longer watches over it.

Previously it was possible for these sends to block indefinitely in the
scenario that the server was shutting down (which means the breach
arbiter) is. As a result, the channel would never be drained, meaning
the server couldn’t complete shutdown as the peer hadn’t exited yet.
2017-08-18 12:16:29 -07:00

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package main
import (
"container/list"
"fmt"
"net"
"strings"
"sync"
"sync/atomic"
"time"
"github.com/davecgh/go-spew/spew"
"github.com/lightningnetwork/lnd/brontide"
"bytes"
"github.com/go-errors/errors"
"github.com/lightningnetwork/lnd/chainntnfs"
"github.com/lightningnetwork/lnd/channeldb"
"github.com/lightningnetwork/lnd/htlcswitch"
"github.com/lightningnetwork/lnd/lnrpc"
"github.com/lightningnetwork/lnd/lnwallet"
"github.com/lightningnetwork/lnd/lnwire"
"github.com/lightningnetwork/lnd/routing"
"github.com/roasbeef/btcd/btcec"
"github.com/roasbeef/btcd/chaincfg/chainhash"
"github.com/roasbeef/btcd/connmgr"
"github.com/roasbeef/btcd/txscript"
"github.com/roasbeef/btcd/wire"
)
var (
numNodes int32
)
const (
// pingInterval is the interval at which ping messages are sent.
pingInterval = 1 * time.Minute
// 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.
}
// newChannelMsg packages a lnwallet.LightningChannel with a channel that
// allows the receiver of the request to report when the funding transaction
// has been confirmed and the channel creation process completed.
type newChannelMsg struct {
channel *lnwallet.LightningChannel
done chan struct{}
}
// chanSnapshotReq is a message sent by outside subsystems 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.
// TODO(roasbeef): proper reconnection logic
type peer struct {
// The following fields are only meant to be used *atomically*
bytesReceived uint64
bytesSent uint64
// pingTime is a rough estimate of the RTT (round-trip-time) between us
// and the connected peer. This time is expressed in micro seconds.
// TODO(roasbeef): also use a WMA or EMA?
pingTime int64
// pingLastSend is the Unix time expressed in nanoseconds when we sent
// our last ping message.
pingLastSend int64
// MUST be used atomically.
started int32
disconnect int32
connReq *connmgr.ConnReq
conn net.Conn
addr *lnwire.NetAddress
pubKeyBytes [33]byte
inbound bool
id int32
// This mutex protects all the stats below it.
sync.RWMutex
timeConnected time.Time
lastSend time.Time
lastRecv time.Time
// 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
// 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.
activeChanMtx sync.RWMutex
activeChannels map[lnwire.ChannelID]*lnwallet.LightningChannel
// newChannels is used by the fundingManager to send fully opened
// channels to the source peer which handled the funding workflow.
newChannels chan *newChannelMsg
// localCloseChanReqs is a channel in which any local requests to close
// a particular channel are sent over.
localCloseChanReqs chan *htlcswitch.ChanClose
// shutdownChanReqs is used to send the Shutdown messages that initiate
// the cooperative close workflow.
shutdownChanReqs chan *lnwire.Shutdown
// closingSignedChanReqs is used to send signatures for proposed
// channel close transactions during the cooperative close workflow.
closingSignedChanReqs chan *lnwire.ClosingSigned
server *server
// localSharedFeatures is a product of comparison of our and their
// local features vectors which consist of features which are present
// on both sides.
localSharedFeatures *lnwire.SharedFeatures
// globalSharedFeatures is a product of comparison of our and their
// global features vectors which consist of features which are present
// on both sides.
globalSharedFeatures *lnwire.SharedFeatures
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, connReq *connmgr.ConnReq, server *server,
addr *lnwire.NetAddress, inbound bool) (*peer, error) {
nodePub := addr.IdentityKey
p := &peer{
conn: conn,
addr: addr,
id: atomic.AddInt32(&numNodes, 1),
inbound: inbound,
connReq: connReq,
server: server,
sendQueue: make(chan outgoinMsg),
outgoingQueue: make(chan outgoinMsg),
activeChannels: make(map[lnwire.ChannelID]*lnwallet.LightningChannel),
newChannels: make(chan *newChannelMsg, 1),
localCloseChanReqs: make(chan *htlcswitch.ChanClose),
shutdownChanReqs: make(chan *lnwire.Shutdown),
closingSignedChanReqs: make(chan *lnwire.ClosingSigned),
localSharedFeatures: nil,
globalSharedFeatures: nil,
queueQuit: make(chan struct{}),
quit: make(chan struct{}),
}
copy(p.pubKeyBytes[:], nodePub.SerializeCompressed())
return p, nil
}
// Start starts all helper goroutines the peer needs for normal operations. In
// the case this peer has already been started, then this function is a loop.
func (p *peer) Start() error {
if atomic.AddInt32(&p.started, 1) != 1 {
return nil
}
peerLog.Tracef("peer %v starting", p)
// Exchange local and global features, the init message should be very
// first between two nodes.
if err := p.sendInitMsg(); err != nil {
return fmt.Errorf("unable to send init msg: %v", err)
}
// Before we launch any of the helper goroutines off the peer struct,
// we'll first ensure proper adherence to the p2p protocol. The init
// message MUST be sent before any other message.
readErr := make(chan error, 1)
msgChan := make(chan lnwire.Message, 1)
p.wg.Add(1)
go func() {
defer p.wg.Done()
msg, err := p.readNextMessage()
if err != nil {
readErr <- err
msgChan <- nil
return
}
readErr <- nil
msgChan <- msg
}()
select {
// In order to avoid blocking indefinitely, we'll give the other peer
// an upper timeout of 15 seconds to respond before we bail out early.
case <-time.After(time.Second * 15):
return fmt.Errorf("peer did not complete handshake within 5 " +
"seconds")
case err := <-readErr:
if err != nil {
return fmt.Errorf("unable to read init msg: %v", err)
}
}
// Once the init message arrives, we can parse it so we can figure out
// the negotiation of features for this session.
msg := <-msgChan
if msg, ok := msg.(*lnwire.Init); ok {
if err := p.handleInitMsg(msg); err != nil {
return err
}
} else {
return errors.New("very first message between nodes " +
"must be init message")
}
// Fetch and then load all the active channels we have with this remote
// peer from the database.
activeChans, err := p.server.chanDB.FetchOpenChannels(p.addr.IdentityKey)
if err != nil {
peerLog.Errorf("unable to fetch active chans "+
"for peer %v: %v", p, err)
return err
}
// Next, load all the active channels we have with this peer,
// registering them with the switch and launching the necessary
// goroutines required to operate them.
peerLog.Debugf("Loaded %v active channels from database with "+
"peerID(%v)", len(activeChans), p.id)
if err := p.loadActiveChannels(activeChans); err != nil {
return fmt.Errorf("unable to load channels: %v", err)
}
p.wg.Add(5)
go p.queueHandler()
go p.writeHandler()
go p.readHandler()
go p.channelManager()
go p.pingHandler()
return 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 {
// If the channel isn't yet open, then we don't need to process
// it any further.
if dbChan.IsPending {
continue
}
lnChan, err := lnwallet.NewLightningChannel(p.server.cc.signer,
p.server.cc.chainNotifier, p.server.cc.feeEstimator, dbChan)
if err != nil {
return err
}
chanPoint := &dbChan.FundingOutpoint
chanID := lnwire.NewChanIDFromOutPoint(chanPoint)
p.activeChanMtx.Lock()
p.activeChannels[chanID] = lnChan
p.activeChanMtx.Unlock()
peerLog.Infof("peerID(%v) loading ChannelPoint(%v)", p.id, chanPoint)
select {
case p.server.breachArbiter.newContracts <- lnChan:
case <-p.server.quit:
return fmt.Errorf("server shutting down")
case <-p.quit:
return fmt.Errorf("peer shutting down")
}
// 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.
blockEpoch, err := p.server.cc.chainNotifier.RegisterBlockEpochNtfn()
if err != nil {
return err
}
_, currentHeight, err := p.server.cc.chainIO.GetBestBlock()
if err != nil {
return err
}
linkCfg := htlcswitch.ChannelLinkConfig{
Peer: p,
DecodeHopIterator: p.server.sphinx.DecodeHopIterator,
DecodeOnionObfuscator: p.server.sphinx.DecodeOnionObfuscator,
GetLastChannelUpdate: createGetLastUpdate(p.server.chanRouter,
p.PubKey(), lnChan.ShortChanID()),
SettledContracts: p.server.breachArbiter.settledContracts,
DebugHTLC: cfg.DebugHTLC,
Registry: p.server.invoices,
Switch: p.server.htlcSwitch,
FwrdingPolicy: p.server.cc.routingPolicy,
BlockEpochs: blockEpoch,
}
link := htlcswitch.NewChannelLink(linkCfg, lnChan,
uint32(currentHeight))
if err := p.server.htlcSwitch.AddLink(link); err != nil {
return err
}
}
return nil
}
// WaitForDisconnect waits until the peer has disconnected. A peer may be
// disconnected if the local or remote side terminating the connection, or an
// irrecoverable protocol error has been encountered.
func (p *peer) WaitForDisconnect() {
<-p.quit
}
// 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(reason error) {
if !atomic.CompareAndSwapInt32(&p.disconnect, 0, 1) {
return
}
peerLog.Tracef("Disconnecting %s, reason: %v", p, reason)
// Ensure that the TCP connection is properly closed before continuing.
p.conn.Close()
close(p.quit)
p.wg.Wait()
}
// 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, error) {
noiseConn, ok := p.conn.(*brontide.Conn)
if !ok {
return nil, fmt.Errorf("brontide.Conn required to read messages")
}
// First we'll read the next _full_ message. We do this rather than
// reading incrementally from the stream as the Lightning wire protocol
// is message oriented and allows nodes to pad on additional data to
// the message stream.
rawMsg, err := noiseConn.ReadNextMessage()
atomic.AddUint64(&p.bytesReceived, uint64(len(rawMsg)))
if err != nil {
return nil, err
}
// Next, create a new io.Reader implementation from the raw message,
// and use this to decode the message directly from.
msgReader := bytes.NewReader(rawMsg)
nextMsg, err := lnwire.ReadMessage(msgReader, 0)
if err != nil {
return nil, err
}
// TODO(roasbeef): add message summaries
p.logWireMessage(nextMsg, true)
return nextMsg, nil
}
// chanMsgStream implements a goroutine-safe, in-order stream of messages to be
// delivered to an active channel. These messages MUST be in order due to the
// nature of the lightning channel commitment state machine. We utilize
// additional synchronization with the fundingManager to ensure we don't
// attempt to dispatch a message to a channel before it is fully active.
type chanMsgStream struct {
fundingMgr *fundingManager
htlcSwitch *htlcswitch.Switch
cid lnwire.ChannelID
peer *peer
msgCond *sync.Cond
msgs []lnwire.Message
chanLink htlcswitch.ChannelLink
mtx sync.Mutex
wg sync.WaitGroup
quit chan struct{}
}
// newChanMsgStream creates a new instance of a chanMsgStream for a particular
// channel identified by its channel ID.
func newChanMsgStream(f *fundingManager, h *htlcswitch.Switch, p *peer,
c lnwire.ChannelID) *chanMsgStream {
stream := &chanMsgStream{
fundingMgr: f,
htlcSwitch: h,
peer: p,
cid: c,
quit: make(chan struct{}),
}
stream.msgCond = sync.NewCond(&stream.mtx)
return stream
}
// Start starts the chanMsgStream.
func (c *chanMsgStream) Start() {
c.wg.Add(1)
go c.msgConsumer()
}
// Stop stops the chanMsgStream.
func (c *chanMsgStream) Stop() {
// TODO(roasbeef): signal too?
close(c.quit)
// Wake up the msgConsumer is we've been signalled to exit.
c.msgCond.Signal()
c.wg.Wait()
}
// msgConsumer is the main goroutine that streams messages from the peer's
// readHandler directly to the target channel.
func (c *chanMsgStream) msgConsumer() {
defer c.wg.Done()
peerLog.Tracef("Update stream for ChannelID(%x) created", c.cid[:])
for {
// First, we'll check our condition. If the queue of messages
// is empty, then we'll wait until a new item is added.
c.msgCond.L.Lock()
for len(c.msgs) == 0 {
c.msgCond.Wait()
// If we were woke up in order to exit, then we'll do
// so. Otherwise, we'll check the message queue for any
// new items.
select {
case <-c.quit:
peerLog.Tracef("Update stream for "+
"ChannelID(%x) exiting", c.cid[:])
c.msgCond.L.Unlock()
return
default:
}
}
// Grab the message off the front of the queue, shifting the
// slice's reference down one in order to remove the message
// from the queue.
msg := c.msgs[0]
c.msgs = c.msgs[1:]
// We'll send a message to the funding manager and wait iff an
// active funding process for this channel hasn't yet
// completed. We do this in order to account for the following
// scenario: we send the funding locked message to the other
// side, they immediately send a channel update message, but we
// haven't yet sent the channel to the channelManager.
c.fundingMgr.waitUntilChannelOpen(c.cid)
// Dispatch the commitment update message to the proper active
// goroutine dedicated to this channel.
if c.chanLink == nil {
link, err := c.htlcSwitch.GetLink(c.cid)
if err != nil {
peerLog.Errorf("recv'd update for unknown "+
"channel %v from %v", c.cid, c.peer)
continue
}
c.chanLink = link
}
c.chanLink.HandleChannelUpdate(msg)
c.msgCond.L.Unlock()
}
}
// AddMsg adds a new message to the chanMsgStream. This function is safe for
// concurrent access.
func (c *chanMsgStream) AddMsg(msg lnwire.Message) {
// First, we'll lock the condition, and add the message to the end of
// the message queue.
c.msgCond.L.Lock()
c.msgs = append(c.msgs, msg)
c.msgCond.L.Unlock()
// With the message added, we signal to the msgConsumer that there are
// additional messages to consume.
c.msgCond.Signal()
}
// readHandler is responsible for reading messages off the wire in series, then
// properly dispatching the handling of the message to the proper subsystem.
//
// NOTE: This method MUST be run as a goroutine.
func (p *peer) readHandler() {
defer p.wg.Done()
chanMsgStreams := make(map[lnwire.ChannelID]*chanMsgStream)
out:
for atomic.LoadInt32(&p.disconnect) == 0 {
nextMsg, err := p.readNextMessage()
if err != nil {
peerLog.Infof("unable to read message from %v: %v",
p, err)
switch err.(type) {
// If this is just a message we don't yet recognize,
// we'll continue processing as normal as this allows
// us to introduce new messages in a forwards
// compatible manner.
case *lnwire.UnknownMessage:
continue
// If the error we encountered wasn't just a message we
// didn't recognize, then we'll stop all processing s
// this is a fatal error.
default:
break out
}
}
var (
isChanUpdate bool
targetChan lnwire.ChannelID
)
switch msg := nextMsg.(type) {
case *lnwire.Pong:
// When we receive a Pong message in response to our
// last ping message, we'll use the time in which we
// sent the ping message to measure a rough estimate of
// round trip time.
pingSendTime := atomic.LoadInt64(&p.pingLastSend)
delay := (time.Now().UnixNano() - pingSendTime) / 1000
atomic.StoreInt64(&p.pingTime, delay)
case *lnwire.Ping:
pongBytes := make([]byte, msg.NumPongBytes)
p.queueMsg(lnwire.NewPong(pongBytes), nil)
case *lnwire.OpenChannel:
p.server.fundingMgr.processFundingOpen(msg, p.addr)
case *lnwire.AcceptChannel:
p.server.fundingMgr.processFundingAccept(msg, p.addr)
case *lnwire.FundingCreated:
p.server.fundingMgr.processFundingCreated(msg, p.addr)
case *lnwire.FundingSigned:
p.server.fundingMgr.processFundingSigned(msg, p.addr)
case *lnwire.FundingLocked:
p.server.fundingMgr.processFundingLocked(msg, p.addr)
case *lnwire.Shutdown:
p.shutdownChanReqs <- msg
case *lnwire.ClosingSigned:
p.closingSignedChanReqs <- msg
case *lnwire.Error:
p.server.fundingMgr.processFundingError(msg, p.addr)
// TODO(roasbeef): create ChanUpdater interface for the below
case *lnwire.UpdateAddHTLC:
isChanUpdate = true
targetChan = msg.ChanID
case *lnwire.UpdateFufillHTLC:
isChanUpdate = true
targetChan = msg.ChanID
case *lnwire.UpdateFailHTLC:
isChanUpdate = true
targetChan = msg.ChanID
case *lnwire.RevokeAndAck:
isChanUpdate = true
targetChan = msg.ChanID
case *lnwire.CommitSig:
isChanUpdate = true
targetChan = msg.ChanID
case *lnwire.UpdateFee:
isChanUpdate = true
targetChan = msg.ChanID
case *lnwire.ChannelUpdate,
*lnwire.ChannelAnnouncement,
*lnwire.NodeAnnouncement,
*lnwire.AnnounceSignatures:
p.server.discoverSrv.ProcessRemoteAnnouncement(msg,
p.addr.IdentityKey)
default:
peerLog.Errorf("unknown message received from peer "+
"%v", p)
}
if isChanUpdate {
// If this is a channel update, then we need to feed it
// into the channel's in-order message stream.
chanStream, ok := chanMsgStreams[targetChan]
if !ok {
// If a stream hasn't yet been created, then
// we'll do so, add it to the map, and finally
// start it.
chanStream = newChanMsgStream(p.server.fundingMgr,
p.server.htlcSwitch, p, targetChan)
chanMsgStreams[targetChan] = chanStream
chanStream.Start()
}
// With the stream obtained, add the message to the
// stream so we can continue processing message.
chanStream.AddMsg(nextMsg)
}
}
p.Disconnect(errors.New("read handler closed"))
for cid, chanStream := range chanMsgStreams {
chanStream.Stop()
delete(chanMsgStreams, cid)
}
peerLog.Tracef("readHandler for peer %v done", p)
}
// logWireMessage logs the receipt or sending of particular wire message. This
// function is used rather than just logging the message in order to produce
// less spammy log messages in trace mode by setting the 'Curve" parameter to
// nil. Doing this avoids printing out each of the field elements in the curve
// parameters for secp256k1.
func (p *peer) logWireMessage(msg lnwire.Message, read bool) {
switch m := msg.(type) {
case *lnwire.RevokeAndAck:
m.NextRevocationKey.Curve = nil
case *lnwire.NodeAnnouncement:
m.NodeID.Curve = nil
case *lnwire.ChannelAnnouncement:
m.NodeID1.Curve = nil
m.NodeID2.Curve = nil
m.BitcoinKey1.Curve = nil
m.BitcoinKey2.Curve = nil
case *lnwire.AcceptChannel:
m.FundingKey.Curve = nil
m.RevocationPoint.Curve = nil
m.PaymentPoint.Curve = nil
m.DelayedPaymentPoint.Curve = nil
m.FirstCommitmentPoint.Curve = nil
case *lnwire.OpenChannel:
m.FundingKey.Curve = nil
m.RevocationPoint.Curve = nil
m.PaymentPoint.Curve = nil
m.DelayedPaymentPoint.Curve = nil
m.FirstCommitmentPoint.Curve = nil
case *lnwire.FundingLocked:
m.NextPerCommitmentPoint.Curve = nil
}
prefix := "readMessage from"
if !read {
prefix = "writeMessage to"
}
peerLog.Tracef(prefix+" %v: %v", p, newLogClosure(func() string {
return spew.Sdump(msg)
}))
}
// 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
p.logWireMessage(msg, false)
// As the Lightning wire protocol is fully message oriented, we only
// allows one wire message per outer encapsulated crypto message. So
// we'll create a temporary buffer to write the message directly to.
var msgPayload [lnwire.MaxMessagePayload]byte
b := bytes.NewBuffer(msgPayload[0:0:len(msgPayload)])
// With the temp buffer created and sliced properly (length zero, full
// capacity), we'll now encode the message directly into this buffer.
n, err := lnwire.WriteMessage(b, msg, 0)
atomic.AddUint64(&p.bytesSent, uint64(n))
// Finally, write the message itself in a single swoop.
_, err = p.conn.Write(b.Bytes())
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() {
defer func() {
p.wg.Done()
peerLog.Tracef("writeHandler for peer %v done", p)
}()
for {
select {
case outMsg := <-p.sendQueue:
switch outMsg.msg.(type) {
// If we're about to send a ping message, then log the
// exact time in which we send the message so we can
// use the delay as a rough estimate of latency to the
// remote peer.
case *lnwire.Ping:
// TODO(roasbeef): do this before the write?
// possibly account for processing within func?
now := time.Now().UnixNano()
atomic.StoreInt64(&p.pingLastSend, now)
}
// Write out the message to the socket, closing the
// 'sentChan' if it's non-nil, The 'sentChan' allows
// callers to optionally synchronize sends with the
// writeHandler.
err := p.writeMessage(outMsg.msg)
if outMsg.sentChan != nil {
close(outMsg.sentChan)
}
if err != nil {
p.Disconnect(errors.Errorf("unable to write message: %v",
err))
return
}
case <-p.quit:
return
}
}
}
// queueHandler is responsible for accepting messages from outside subsystems
// to be eventually sent out on the wire by the writeHandler.
//
// NOTE: This method MUST be run as a goroutine.
func (p *peer) queueHandler() {
defer p.wg.Done()
pendingMsgs := list.New()
for {
// Before add a queue'd message our pending message queue,
// we'll first try to aggressively empty out our pending list of
// messaging.
for {
// Examine the front of the queue. If this message is
// nil, then we've emptied out the queue and can accept
// new messages from outside sub-systems.
elem := pendingMsgs.Front()
if elem == nil {
break
}
select {
case p.sendQueue <- elem.Value.(outgoinMsg):
pendingMsgs.Remove(elem)
case <-p.quit:
return
default:
break
}
}
// If there weren't any messages to send, or the writehandler
// is still blocked, then we'll accept a new message into the
// queue from outside sub-systems.
select {
case <-p.quit:
return
case msg := <-p.outgoingQueue:
pendingMsgs.PushBack(msg)
}
}
}
// pingHandler is responsible for periodically sending ping messages to the
// remote peer in order to keep the connection alive and/or determine if the
// connection is still active.
//
// NOTE: This method MUST be run as a goroutine.
func (p *peer) pingHandler() {
defer p.wg.Done()
pingTicker := time.NewTicker(pingInterval)
defer pingTicker.Stop()
// TODO(roasbeef): make dynamic in order to create fake cover traffic
const numPingBytes = 16
out:
for {
select {
case <-pingTicker.C:
p.queueMsg(lnwire.NewPing(numPingBytes), nil)
case <-p.quit:
break out
}
}
}
// PingTime returns the estimated ping time to the peer in microseconds.
func (p *peer) PingTime() int64 {
return atomic.LoadInt64(&p.pingTime)
}
// queueMsg queues a new lnwire.Message to be eventually sent out on the
// wire.
func (p *peer) queueMsg(msg lnwire.Message, doneChan chan struct{}) {
select {
case p.outgoingQueue <- outgoinMsg{msg, doneChan}:
case <-p.quit:
return
}
}
// ChannelSnapshots returns a slice of channel snapshots detailing all
// currently active channels maintained with the remote peer.
func (p *peer) ChannelSnapshots() []*channeldb.ChannelSnapshot {
p.activeChanMtx.RLock()
defer p.activeChanMtx.RUnlock()
snapshots := make([]*channeldb.ChannelSnapshot, 0, len(p.activeChannels))
for _, activeChan := range p.activeChannels {
snapshot := activeChan.StateSnapshot()
snapshots = append(snapshots, snapshot)
}
return snapshots
}
// closingScripts are the set of clsoign deslivery scripts for each party. This
// intermediate state is maintained for each active close negotiation, as the
// final signatures sent must cover the specified delivery scripts for each
// party.
type closingScripts struct {
localScript []byte
remoteScript []byte
}
// 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() {
defer p.wg.Done()
// chanShutdowns is a map of channels for which our node has initiated
// a cooperative channel close. When an lnwire.Shutdown is received,
// this allows the node to determine the next step to be taken in the
// workflow.
chanShutdowns := make(map[lnwire.ChannelID]*htlcswitch.ChanClose)
deliveryAddrs := make(map[lnwire.ChannelID]*closingScripts)
// initiator[ShutdownSigs|FeeProposals] holds the
// [signature|feeProposal] for the last ClosingSigned sent to the peer
// by the initiator. This enables us to respond to subsequent steps in
// the workflow without having to recalculate our signature for the
// channel close transaction, and track the sent fee proposals for fee
// negotiation purposes.
initiatorShutdownSigs := make(map[lnwire.ChannelID][]byte)
initiatorFeeProposals := make(map[lnwire.ChannelID]uint64)
// responder[ShutdownSigs|FeeProposals] is similar to the the maps
// above, just for the responder.
responderShutdownSigs := make(map[lnwire.ChannelID][]byte)
responderFeeProposals := make(map[lnwire.ChannelID]uint64)
// TODO(roasbeef): move to cfg closure func
genDeliveryScript := func() ([]byte, error) {
deliveryAddr, err := p.server.cc.wallet.NewAddress(
lnwallet.WitnessPubKey, false,
)
if err != nil {
return nil, err
}
peerLog.Infof("Delivery addr for channel close: %v",
deliveryAddr)
return txscript.PayToAddrScript(deliveryAddr)
}
out:
for {
select {
// A new channel has arrived which means we've just completed a
// funding workflow. We'll initialize the necessary local
// state, and notify the htlc switch of a new link.
case newChanReq := <-p.newChannels:
chanPoint := newChanReq.channel.ChannelPoint()
chanID := lnwire.NewChanIDFromOutPoint(chanPoint)
newChan := newChanReq.channel
// First, we'll add this channel to the set of active
// channels, so we can look it up later easily
// according to its channel ID.
p.activeChanMtx.Lock()
p.activeChannels[chanID] = newChan
p.activeChanMtx.Unlock()
peerLog.Infof("New channel active ChannelPoint(%v) "+
"with peerId(%v)", chanPoint, p.id)
// Next, we'll assemble a ChannelLink along with the
// necessary items it needs to function.
//
// TODO(roasbeef): panic on below?
blockEpoch, err := p.server.cc.chainNotifier.RegisterBlockEpochNtfn()
if err != nil {
peerLog.Errorf("unable to register for block epoch: %v", err)
continue
}
_, currentHeight, err := p.server.cc.chainIO.GetBestBlock()
if err != nil {
peerLog.Errorf("unable to get best block: %v", err)
continue
}
linkConfig := htlcswitch.ChannelLinkConfig{
Peer: p,
DecodeHopIterator: p.server.sphinx.DecodeHopIterator,
DecodeOnionObfuscator: p.server.sphinx.DecodeOnionObfuscator,
GetLastChannelUpdate: createGetLastUpdate(p.server.chanRouter,
p.PubKey(), newChanReq.channel.ShortChanID()),
SettledContracts: p.server.breachArbiter.settledContracts,
DebugHTLC: cfg.DebugHTLC,
Registry: p.server.invoices,
Switch: p.server.htlcSwitch,
FwrdingPolicy: p.server.cc.routingPolicy,
BlockEpochs: blockEpoch,
}
link := htlcswitch.NewChannelLink(linkConfig, newChan,
uint32(currentHeight))
// With the channel link created, we'll now notify the
// htlc switch so this channel can be used to dispatch
// local payments and also passively forward payments.
if err := p.server.htlcSwitch.AddLink(link); err != nil {
peerLog.Errorf("can't register new channel "+
"link(%v) with peerId(%v)", chanPoint, p.id)
}
close(newChanReq.done)
// We've just received a local quest to close an active
// channel.
case req := <-p.localCloseChanReqs:
// So we'll first transition the channel to a state of
// pending shutdown.
chanID := lnwire.NewChanIDFromOutPoint(req.ChanPoint)
// We'll only track this shutdown request if this is a
// regular close request, and not in response to a
// channel breach.
var (
deliveryScript []byte
err error
)
if req.CloseType == htlcswitch.CloseRegular {
chanShutdowns[chanID] = req
// As we need to close out the channel and
// claim our funds on-chain, we'll request a
// new delivery address from the wallet, and
// turn that into it corresponding output
// script.
deliveryScript, err = genDeliveryScript()
if err != nil {
cErr := fmt.Errorf("Unable to generate "+
"delivery address: %v", err)
peerLog.Errorf(cErr.Error())
req.Err <- cErr
continue
}
// We'll also track this delivery script, as
// we'll need it to reconstruct the cooperative
// closure transaction during our closing fee
// negotiation ratchet.
deliveryAddrs[chanID] = &closingScripts{
localScript: deliveryScript,
}
}
// With the state marked as shutting down, we can now
// proceed with the channel close workflow. If this is
// regular close, we'll send a shutdown. Otherwise,
// we'll simply be clearing our indexes.
p.handleLocalClose(req, deliveryScript)
// A receipt of a message over this channel indicates that
// either a shutdown proposal has been initiated, or a prior
// one has been completed, advancing to the next state of
// channel closure.
case req := <-p.shutdownChanReqs:
// If we don't have a channel that matches this channel
// ID, then we'll ignore this message.
chanID := req.ChannelID
p.activeChanMtx.Lock()
_, ok := p.activeChannels[chanID]
p.activeChanMtx.Unlock()
if !ok {
peerLog.Warnf("Received unsolicited shutdown msg: %v",
spew.Sdump(req))
continue
}
// First, we'll track their delivery script for when we
// ultimately create the cooperative closure
// transaction.
deliveryScripts, ok := deliveryAddrs[chanID]
if !ok {
deliveryAddrs[chanID] = &closingScripts{}
deliveryScripts = deliveryAddrs[chanID]
}
deliveryScripts.remoteScript = req.Address
// Next, we'll check in the shutdown map to see if
// we're the initiator or not. If we don't have an
// entry for this channel, then this means that we're
// the responder to the workflow.
if _, ok := chanShutdowns[req.ChannelID]; !ok {
// Check responderShutdownSigs for an already
// existing shutdown signature for this channel.
// If such a signature exists, it means we
// already have sent a response to a shutdown
// message for this channel, so ignore this one.
_, exists := responderShutdownSigs[req.ChannelID]
if exists {
continue
}
// As we're the responder, we'll need to
// generate a delivery script of our own.
deliveryScript, err := genDeliveryScript()
if err != nil {
peerLog.Errorf("Unable to generate "+
"delivery address: %v", err)
continue
}
deliveryScripts.localScript = deliveryScript
// In this case, we'll send a shutdown message,
// and also prep our closing signature for the
// case the fees are immediately agreed upon.
closeSig, proposedFee := p.handleShutdownResponse(
req, deliveryScript)
if closeSig != nil {
responderShutdownSigs[req.ChannelID] = closeSig
responderFeeProposals[req.ChannelID] = proposedFee
}
}
// A receipt of a message over this channel indicates that the
// final stage of a channel shutdown workflow has been
// completed.
case req := <-p.closingSignedChanReqs:
// First we'll check if this has an entry in the local
// shutdown map.
chanID := req.ChannelID
localCloseReq, ok := chanShutdowns[chanID]
// If it does, then this means we were the initiator of
// the channel shutdown procedure.
if ok {
shutdownSig := initiatorShutdownSigs[req.ChannelID]
initiatorSig := append(shutdownSig,
byte(txscript.SigHashAll))
// To finalize this shtudown, we'll now send a
// matching close signed message to the other
// party, and broadcast the closing transaction
// to the network. If the fees are still being
// negotiated, handleClosingSigned returns the
// signature and proposed fee we sent to the
// peer. In the case fee negotiation was
// complete, and the closing tx was broadcasted,
// closeSig will be nil, and we can delete the
// state associated with this channel shutdown.
closeSig, proposedFee := p.handleClosingSigned(
localCloseReq, req,
deliveryAddrs[chanID], initiatorSig,
initiatorFeeProposals[req.ChannelID])
if closeSig != nil {
initiatorShutdownSigs[req.ChannelID] = closeSig
initiatorFeeProposals[req.ChannelID] = proposedFee
} else {
delete(initiatorShutdownSigs, req.ChannelID)
delete(initiatorFeeProposals, req.ChannelID)
delete(chanShutdowns, req.ChannelID)
delete(deliveryAddrs, req.ChannelID)
}
continue
}
shutdownSig := responderShutdownSigs[req.ChannelID]
responderSig := append(shutdownSig,
byte(txscript.SigHashAll))
// Otherwise, we're the responder to the channel
// shutdown procedure. The procedure will be the same,
// but we don't have a local request to to notify about
// updates, so just pass in nil instead.
closeSig, proposedFee := p.handleClosingSigned(nil, req,
deliveryAddrs[chanID], responderSig,
responderFeeProposals[req.ChannelID])
if closeSig != nil {
responderShutdownSigs[req.ChannelID] = closeSig
responderFeeProposals[req.ChannelID] = proposedFee
} else {
delete(responderShutdownSigs, req.ChannelID)
delete(responderFeeProposals, req.ChannelID)
delete(deliveryAddrs, chanID)
}
case <-p.quit:
break out
}
}
}
// handleLocalClose kicks-off the workflow to execute a cooperative or forced
// unilateral closure of the channel initiated by a local subsystem.
//
// TODO(roasbeef): if no more active channels with peer call Remove on connMgr
// with peerID
func (p *peer) handleLocalClose(req *htlcswitch.ChanClose, deliveryScript []byte) {
chanID := lnwire.NewChanIDFromOutPoint(req.ChanPoint)
p.activeChanMtx.RLock()
channel, ok := p.activeChannels[chanID]
p.activeChanMtx.RUnlock()
if !ok {
err := fmt.Errorf("unable to close channel, ChannelID(%v) is "+
"unknown", chanID)
peerLog.Errorf(err.Error())
req.Err <- err
return
}
switch req.CloseType {
// A type of CloseRegular indicates that the user has opted to close
// out this channel on-chain, so we execute the cooperative channel
// closure workflow.
case htlcswitch.CloseRegular:
err := p.sendShutdown(channel, deliveryScript)
if err != nil {
req.Err <- err
return
}
// A type of CloseBreach indicates that the counterparty has breached
// the channel therefore we need to clean up our local state.
case htlcswitch.CloseBreach:
// TODO(roasbeef): no longer need with newer beach logic?
peerLog.Infof("ChannelPoint(%v) has been breached, wiping "+
"channel", req.ChanPoint)
if err := p.WipeChannel(channel); err != nil {
peerLog.Infof("Unable to wipe channel after detected "+
"breach: %v", err)
req.Err <- err
return
}
return
}
}
// handleShutdownResponse is called when a responder in a cooperative channel
// close workflow receives a Shutdown message. This is the second step in the
// cooperative close workflow. This function generates a close transaction with
// a proposed fee amount and sends the signed transaction to the initiator.
// Returns the signature used to signed the close proposal, and the proposed
// fee.
func (p *peer) handleShutdownResponse(msg *lnwire.Shutdown,
localDeliveryScript []byte) ([]byte, uint64) {
p.activeChanMtx.RLock()
channel, ok := p.activeChannels[msg.ChannelID]
p.activeChanMtx.RUnlock()
if !ok {
peerLog.Errorf("unable to close channel, ChannelPoint(%v) is "+
"unknown", msg.ChannelID)
return nil, 0
}
// As we just received a shutdown message, we'll also send a shutdown
// message with our desired fee so we can start the negotiation.
err := p.sendShutdown(channel, localDeliveryScript)
if err != nil {
peerLog.Errorf("error while sending shutdown message: %v", err)
return nil, 0
}
// Calculate an initial proposed fee rate for the close transaction.
feeRate := p.server.cc.feeEstimator.EstimateFeePerWeight(1) * 1000
// We propose a fee and send a close proposal to the peer. This will
// start the fee negotiations. Once both sides agree on a fee, we'll
// create a signature that closes the channel using the agreed upon fee.
fee := channel.CalcFee(feeRate)
closeSig, proposedFee, err := channel.CreateCloseProposal(
fee, localDeliveryScript, msg.Address,
)
if err != nil {
peerLog.Errorf("unable to create close proposal: %v", err)
return nil, 0
}
parsedSig, err := btcec.ParseSignature(closeSig, btcec.S256())
if err != nil {
peerLog.Errorf("unable to parse signature: %v", err)
return nil, 0
}
// With the closing signature assembled, we'll send the matching close
// signed message to the other party so they can broadcast the closing
// transaction if they agree with the fee, or create a new close
// proposal if they don't.
closingSigned := lnwire.NewClosingSigned(msg.ChannelID, proposedFee,
parsedSig)
p.queueMsg(closingSigned, nil)
return closeSig, proposedFee
}
// calculateCompromiseFee performs the current fee negotiation algorithm,
// taking into consideration our ideal fee based on current fee environment,
// the fee we last proposed (if any), and the fee proposed by the peer.
func calculateCompromiseFee(ourIdealFee, lastSentFee, peerFee uint64) uint64 {
// We will accept a proposed fee in the interval
// [0.5*ourIdealFee, 2*ourIdealFee]. If the peer's fee doesn't fall in
// this range, we'll propose the average of the peer's fee and our last
// sent fee, as long as it is in this range.
// TODO(halseth): Dynamic fee to determine what we consider min/max for
// timely confirmation.
maxFee := 2 * ourIdealFee
minFee := ourIdealFee / 2
// If we didn't propose a fee before, just use our ideal fee value for
// the average calculation.
if lastSentFee == 0 {
lastSentFee = ourIdealFee
}
avgFee := (lastSentFee + peerFee) / 2
switch {
case peerFee <= maxFee && peerFee >= minFee:
// Peer fee is in the accepted range.
return peerFee
case avgFee <= maxFee && avgFee >= minFee:
// The peer's fee is not in the accepted range, but the average
// fee is.
return avgFee
case avgFee > maxFee:
// TODO(halseth): We must ensure fee is not higher than the
// current fee on the commitment transaction.
// We cannot accept the average fee, as it is more than twice
// our own estimate. Set our proposed to the maximum we can
// accept.
return maxFee
default:
// Cannot accept the average, as we consider it too low.
return minFee
}
}
// handleClosingSigned is called when the a ClosingSigned message is received
// from the peer. If we are the initiator in the shutdown procedure, localReq
// should be set to the local close request. If we are the responder, it should
// be set to nil.
//
// This method sends the necessary ClosingSigned message to continue fee
// negotiation, and in case we agreed on a fee completes the channel close
// transaction, and then broadcasts it. It also performs channel cleanup (and
// reports status back to the caller if this was a local shutdown request).
//
// It returns the signature and the proposed fee included in the ClosingSigned
// sent to the peer.
//
// Following the broadcast, both the initiator and responder in the channel
// closure workflow should watch the blockchain for a confirmation of the
// closing transaction before considering the channel terminated. In the case
// of an unresponsive remote party, the initiator can either choose to execute
// a force closure, or backoff for a period of time, and retry the cooperative
// closure.
func (p *peer) handleClosingSigned(localReq *htlcswitch.ChanClose,
msg *lnwire.ClosingSigned, deliveryScripts *closingScripts,
lastSig []byte, lastFee uint64) ([]byte, uint64) {
chanID := msg.ChannelID
p.activeChanMtx.RLock()
channel, ok := p.activeChannels[chanID]
p.activeChanMtx.RUnlock()
if !ok {
err := fmt.Errorf("unable to close channel, ChannelID(%v) is "+
"unknown", chanID)
peerLog.Errorf(err.Error())
if localReq != nil {
localReq.Err <- err
}
return nil, 0
}
// We now consider the fee proposed by the peer, together with the fee
// we last proposed (if any). This method will in case more fee
// negotiation is necessary send a new ClosingSigned message to the peer
// with our new proposed fee. In case we can agree on a fee, it will
// assemble the close transaction, and we can go on to broadcasting it.
closeTx, ourSig, ourFee, err := p.negotiateFeeAndCreateCloseTx(channel,
msg, deliveryScripts, lastSig, lastFee)
if err != nil {
if localReq != nil {
localReq.Err <- err
}
return nil, 0
}
// If closeTx == nil it means that we did not agree on a fee, but we
// proposed a new fee to the peer. Return the signature used for this
// new proposal, and the fee we proposed, for use when we get a reponse.
if closeTx == nil {
return ourSig, ourFee
}
chanPoint := channel.ChannelPoint()
select {
case p.server.breachArbiter.settledContracts <- chanPoint:
case <-p.server.quit:
return nil, 0
case <-p.quit:
return nil, 0
}
// We agreed on a fee, and we can 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.cc.wallet.PublishTransaction(closeTx); err != nil {
// TODO(halseth): Add relevant error types to the
// WalletController interface as this is quite fragile.
if strings.Contains(err.Error(), "already exists") ||
strings.Contains(err.Error(), "already have") {
peerLog.Infof("channel close tx from ChannelPoint(%v) "+
" already exist, probably broadcasted by peer: %v",
chanPoint, err)
} else {
peerLog.Errorf("channel close tx from ChannelPoint(%v) "+
" rejected: %v", chanPoint, err)
// TODO(roasbeef): send ErrorGeneric to other side
return nil, 0
}
}
// Once we've completed the cooperative channel closure, we'll wipe the
// channel so we reject any incoming forward or payment requests via
// this channel.
if err := p.WipeChannel(channel); err != nil {
if localReq != nil {
localReq.Err <- err
}
return nil, 0
}
// TODO(roasbeef): also add closure height to summary
// Clear out the current channel state, marking the channel as being
// closed within the database.
closingTxid := closeTx.TxHash()
chanInfo := channel.StateSnapshot()
closeSummary := &channeldb.ChannelCloseSummary{
ChanPoint: *chanPoint,
ClosingTXID: closingTxid,
RemotePub: &chanInfo.RemoteIdentity,
Capacity: chanInfo.Capacity,
SettledBalance: chanInfo.LocalBalance,
CloseType: channeldb.CooperativeClose,
IsPending: true,
}
if err := channel.DeleteState(closeSummary); err != nil {
if localReq != nil {
localReq.Err <- err
}
return nil, 0
}
// If this is a locally requested shutdown, update the caller with a new
// event detailing the current pending state of this request.
if localReq != nil {
localReq.Updates <- &lnrpc.CloseStatusUpdate{
Update: &lnrpc.CloseStatusUpdate_ClosePending{
ClosePending: &lnrpc.PendingUpdate{
Txid: closingTxid[:],
},
},
}
}
_, bestHeight, err := p.server.cc.chainIO.GetBestBlock()
if err != nil {
if localReq != nil {
localReq.Err <- err
}
return nil, 0
}
// Finally, launch a goroutine which will request to be notified by the
// ChainNotifier once the closure transaction obtains a single
// confirmation.
notifier := p.server.cc.chainNotifier
// If any error happens during waitForChanToClose, forard it to
// localReq. If this channel closure is not locally initiated, localReq
// will be nil, so just ignore the error.
errChan := make(chan error, 1)
if localReq != nil {
errChan = localReq.Err
}
go waitForChanToClose(uint32(bestHeight), notifier, errChan,
chanPoint, &closingTxid, func() {
// First, we'll mark the database as being fully closed
// so we'll no longer watch for its ultimate closure
// upon startup.
err := p.server.chanDB.MarkChanFullyClosed(chanPoint)
if err != nil {
if localReq != nil {
localReq.Err <- err
}
return
}
// Respond to the local subsystem which requested the
// channel closure.
if localReq != nil {
localReq.Updates <- &lnrpc.CloseStatusUpdate{
Update: &lnrpc.CloseStatusUpdate_ChanClose{
ChanClose: &lnrpc.ChannelCloseUpdate{
ClosingTxid: closingTxid[:],
Success: true,
},
},
}
}
})
return nil, 0
}
// negotiateFeeAndCreateCloseTx takes into consideration the closing transaction
// fee proposed by the remote peer in the ClosingSigned message and our
// previously proposed fee (set to 0 if no previous), and continues the fee
// negotiation it process. In case the peer agreed on the same fee as we
// previously sent, it will assemble the close transaction and broadcast it. In
// case the peer propose a fee different from our previous proposal, but that
// can be accepted, a ClosingSigned message with the accepted fee is sent,
// before the closing transaction is broadcasted. In the case where we cannot
// accept the peer's proposed fee, a new fee proposal will be sent.
//
// TODO(halseth): In the case where we cannot accept the fee, and we cannot
// make more proposals, this method should return an error, and we should fail
// the channel.
func (p *peer) negotiateFeeAndCreateCloseTx(channel *lnwallet.LightningChannel,
msg *lnwire.ClosingSigned, deliveryScripts *closingScripts, ourSig []byte,
ourFeeProp uint64) (*wire.MsgTx, []byte, uint64, error) {
peerFeeProposal := msg.FeeSatoshis
// If the fee proposed by the peer is different from what we proposed
// before (or we did not propose anything yet), we must check if we can
// accept the proposal, or if we should negotiate.
if peerFeeProposal != ourFeeProp {
// The peer has suggested a different fee from what we proposed.
// Let's calculate if this one is tolerable.
ourIdealFeeRate := p.server.cc.feeEstimator.
EstimateFeePerWeight(1) * 1000
ourIdealFee := channel.CalcFee(ourIdealFeeRate)
fee := calculateCompromiseFee(ourIdealFee, ourFeeProp,
peerFeeProposal)
// Our new proposed fee must be strictly between what we
// proposed before and what the peer proposed.
isAcceptable := false
if fee < peerFeeProposal && fee > ourFeeProp {
isAcceptable = true
}
if fee < ourFeeProp && fee > peerFeeProposal {
isAcceptable = true
}
if !isAcceptable {
// TODO(halseth): fail channel
}
// Since the compromise fee is different from the fee we last
// proposed, we must update our proposal.
// Create a new close proposal with the compromise fee, and
// send this to the peer.
closeSig, proposedFee, err := channel.CreateCloseProposal(fee,
deliveryScripts.localScript, deliveryScripts.remoteScript)
if err != nil {
peerLog.Errorf("unable to create close proposal: %v",
err)
return nil, nil, 0, err
}
parsedSig, err := btcec.ParseSignature(closeSig, btcec.S256())
if err != nil {
peerLog.Errorf("unable to parse signature: %v", err)
return nil, nil, 0, err
}
closingSigned := lnwire.NewClosingSigned(msg.ChannelID,
proposedFee, parsedSig)
p.queueMsg(closingSigned, nil)
// If the compromise fee was different from what the peer
// proposed, then we must return and wait for an answer, if not
// we can go on to complete the close transaction.
if fee != peerFeeProposal {
return nil, closeSig, proposedFee, nil
}
// We accept the fee proposed by the peer, so prepare our
// signature to complete the close transaction.
ourSig = append(closeSig, byte(txscript.SigHashAll))
}
// We agreed on a fee, and we have the peer's signature for this fee,
// so we can assemble the close tx.
peerSig := append(msg.Signature.Serialize(), byte(txscript.SigHashAll))
chanPoint := channel.ChannelPoint()
closeTx, err := channel.CompleteCooperativeClose(ourSig, peerSig,
deliveryScripts.localScript, deliveryScripts.remoteScript,
peerFeeProposal)
if err != nil {
peerLog.Errorf("unable to complete cooperative "+
"close for ChannelPoint(%v): %v",
chanPoint, err)
// TODO(roasbeef): send ErrorGeneric to other side
return nil, nil, 0, err
}
return closeTx, nil, 0, nil
}
// waitForChanToClose uses the passed notifier to wait until the channel has
// been detected as closed on chain and then concludes by executing the
// following actions: the channel point will be sent over the settleChan, and
// finally the callback will be executed. If any error is encountered within
// the function, then it will be sent over the errChan.
func waitForChanToClose(bestHeight uint32, notifier chainntnfs.ChainNotifier,
errChan chan error, chanPoint *wire.OutPoint,
closingTxID *chainhash.Hash, cb func()) {
peerLog.Infof("Waiting for confirmation of cooperative close of "+
"ChannelPoint(%v) with txid: %v", chanPoint,
closingTxID)
// TODO(roasbeef): add param for num needed confs
confNtfn, err := notifier.RegisterConfirmationsNtfn(closingTxID, 1,
bestHeight)
if err != nil {
if errChan != nil {
errChan <- err
}
return
}
// In the case that the ChainNotifier is shutting down, all subscriber
// notification channels will be closed, generating a nil receive.
height, ok := <-confNtfn.Confirmed
if !ok {
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", chanPoint, height.BlockHeight)
// Finally, execute the closure call back to mark the confirmation of
// the transaction closing the contract.
cb()
}
// sendShutdown handles the creation and sending of the Shutdown messages sent
// between peers to initiate the cooperative channel close workflow. In
// addition, sendShutdown also signals to the HTLC switch to stop accepting
// HTLCs for the specified channel.
func (p *peer) sendShutdown(channel *lnwallet.LightningChannel,
deliveryScript []byte) error {
// In order to construct the shutdown message, we'll need to
// reconstruct the channelID, and the current set delivery script for
// the channel closure.
chanID := lnwire.NewChanIDFromOutPoint(channel.ChannelPoint())
// With both items constructed we'll now send the shutdown message for
// this particular channel, advertising a shutdown request to our
// desired closing script.
shutdown := lnwire.NewShutdown(chanID, deliveryScript)
p.queueMsg(shutdown, nil)
// Finally, we'll unregister the link from the switch in order to
// Prevent the HTLC switch from receiving additional HTLCs for this
// channel.
p.server.htlcSwitch.RemoveLink(chanID)
return nil
}
// WipeChannel removes the passed channel from all indexes associated with the
// peer, and deletes the channel from the database.
func (p *peer) WipeChannel(channel *lnwallet.LightningChannel) error {
channel.Stop()
chanID := lnwire.NewChanIDFromOutPoint(channel.ChannelPoint())
p.activeChanMtx.Lock()
delete(p.activeChannels, chanID)
p.activeChanMtx.Unlock()
// Instruct the Htlc Switch to close this link as the channel is no
// longer active.
if err := p.server.htlcSwitch.RemoveLink(chanID); err != nil {
if err == htlcswitch.ErrChannelLinkNotFound {
peerLog.Warnf("unable remove channel link with "+
"ChannelPoint(%v): %v", chanID, err)
return nil
}
return err
}
return nil
}
// handleInitMsg handles the incoming init message which contains global and
// local features vectors. If feature vectors are incompatible then disconnect.
func (p *peer) handleInitMsg(msg *lnwire.Init) error {
localSharedFeatures, err := p.server.localFeatures.Compare(msg.LocalFeatures)
if err != nil {
err := errors.Errorf("can't compare remote and local feature "+
"vectors: %v", err)
peerLog.Error(err)
return err
}
p.localSharedFeatures = localSharedFeatures
globalSharedFeatures, err := p.server.globalFeatures.Compare(msg.GlobalFeatures)
if err != nil {
err := errors.Errorf("can't compare remote and global feature "+
"vectors: %v", err)
peerLog.Error(err)
return err
}
p.globalSharedFeatures = globalSharedFeatures
return nil
}
// sendInitMsg sends init message to remote peer which contains our currently
// supported local and global features.
func (p *peer) sendInitMsg() error {
msg := lnwire.NewInitMessage(
p.server.globalFeatures,
p.server.localFeatures,
)
return p.writeMessage(msg)
}
// SendMessage queues a message for sending to the target peer.
func (p *peer) SendMessage(msg lnwire.Message) error {
p.queueMsg(msg, nil)
return nil
}
// PubKey returns the pubkey of the peer in compressed serialized format.
func (p *peer) PubKey() [33]byte {
return p.pubKeyBytes
}
// TODO(roasbeef): make all start/stop mutexes a CAS
// createGetLastUpdate returns the handler which serve as a source of the last
// update of the channel in a form of lnwire update message.
func createGetLastUpdate(router *routing.ChannelRouter,
pubKey [33]byte, chanID lnwire.ShortChannelID) func() (*lnwire.ChannelUpdate,
error) {
return func() (*lnwire.ChannelUpdate, error) {
_, edge1, edge2, err := router.GetChannelByID(chanID)
if err != nil {
return nil, err
}
if edge1 == nil || edge2 == nil {
return nil, errors.Errorf("unable to find "+
"channel by ShortChannelID(%v)", chanID)
}
var local *channeldb.ChannelEdgePolicy
if bytes.Compare(edge1.Node.PubKey.SerializeCompressed(),
pubKey[:]) == 0 {
local = edge2
} else {
local = edge1
}
return &lnwire.ChannelUpdate{
Signature: local.Signature,
ShortChannelID: lnwire.NewShortChanIDFromInt(local.ChannelID),
Timestamp: uint32(time.Now().Unix()),
Flags: local.Flags,
TimeLockDelta: local.TimeLockDelta,
HtlcMinimumMsat: uint64(local.MinHTLC),
BaseFee: uint32(local.FeeBaseMSat),
FeeRate: uint32(local.FeeProportionalMillionths),
}, nil
}
}