package htlcswitch
import (
"bytes"
"crypto/sha256"
"fmt"
prand "math/rand"
"sync"
"sync/atomic"
"time"
"github.com/btcsuite/btcd/wire"
"github.com/davecgh/go-spew/spew"
"github.com/go-errors/errors"
"github.com/lightningnetwork/lnd/channeldb"
"github.com/lightningnetwork/lnd/contractcourt"
"github.com/lightningnetwork/lnd/htlcswitch/hodl"
"github.com/lightningnetwork/lnd/input"
"github.com/lightningnetwork/lnd/invoices"
"github.com/lightningnetwork/lnd/lnpeer"
"github.com/lightningnetwork/lnd/lntypes"
"github.com/lightningnetwork/lnd/lnwallet"
"github.com/lightningnetwork/lnd/lnwire"
"github.com/lightningnetwork/lnd/queue"
"github.com/lightningnetwork/lnd/ticker"
)
func init() {
prand.Seed(time.Now().UnixNano())
}
const (
// DefaultMaxOutgoingCltvExpiry is the maximum outgoing time lock that
// the node accepts for forwarded payments. The value is relative to the
// current block height. The reason to have a maximum is to prevent
// funds getting locked up unreasonably long. Otherwise, an attacker
// willing to lock its own funds too, could force the funds of this node
// to be locked up for an indefinite (max int32) number of blocks.
//
// The value 1008 corresponds to on average one week worth of blocks and
// is based on the maximum number of hops (20), the default cltv delta
// (40) and some extra margin to account for the other lightning
// implementations.
DefaultMaxOutgoingCltvExpiry = 1008
// DefaultMinLinkFeeUpdateTimeout represents the minimum interval in
// which a link should propose to update its commitment fee rate.
DefaultMinLinkFeeUpdateTimeout = 10 * time.Minute
// DefaultMaxLinkFeeUpdateTimeout represents the maximum interval in
// which a link should propose to update its commitment fee rate.
DefaultMaxLinkFeeUpdateTimeout = 60 * time.Minute
)
// ForwardingPolicy describes the set of constraints that a given ChannelLink
// is to adhere to when forwarding HTLC's. For each incoming HTLC, this set of
// constraints will be consulted in order to ensure that adequate fees are
// paid, and our time-lock parameters are respected. In the event that an
// incoming HTLC violates any of these constraints, it is to be _rejected_ with
// the error possibly carrying along a ChannelUpdate message that includes the
// latest policy.
type ForwardingPolicy struct {
// MinHTLC is the smallest HTLC that is to be forwarded. This is
// set when a channel is first opened, and will be static for the
// lifetime of the channel.
MinHTLC lnwire.MilliSatoshi
// MaxHTLC is the largest HTLC that is to be forwarded.
MaxHTLC lnwire.MilliSatoshi
// BaseFee is the base fee, expressed in milli-satoshi that must be
// paid for each incoming HTLC. This field, combined with FeeRate is
// used to compute the required fee for a given HTLC.
BaseFee lnwire.MilliSatoshi
// FeeRate is the fee rate, expressed in milli-satoshi that must be
// paid for each incoming HTLC. This field combined with BaseFee is
// used to compute the required fee for a given HTLC.
FeeRate lnwire.MilliSatoshi
// TimeLockDelta is the absolute time-lock value, expressed in blocks,
// that will be subtracted from an incoming HTLC's timelock value to
// create the time-lock value for the forwarded outgoing HTLC. The
// following constraint MUST hold for an HTLC to be forwarded:
//
// * incomingHtlc.timeLock - timeLockDelta = fwdInfo.OutgoingCTLV
//
// where fwdInfo is the forwarding information extracted from the
// per-hop payload of the incoming HTLC's onion packet.
TimeLockDelta uint32
// TODO(roasbeef): add fee module inside of switch
}
// ExpectedFee computes the expected fee for a given htlc amount. The value
// returned from this function is to be used as a sanity check when forwarding
// HTLC's to ensure that an incoming HTLC properly adheres to our propagated
// forwarding policy.
//
// TODO(roasbeef): also add in current available channel bandwidth, inverse
// func
func ExpectedFee(f ForwardingPolicy,
htlcAmt lnwire.MilliSatoshi) lnwire.MilliSatoshi {
return f.BaseFee + (htlcAmt*f.FeeRate)/1000000
}
// ChannelLinkConfig defines the configuration for the channel link. ALL
// elements within the configuration MUST be non-nil for channel link to carry
// out its duties.
type ChannelLinkConfig struct {
// FwrdingPolicy is the initial forwarding policy to be used when
// deciding whether to forwarding incoming HTLC's or not. This value
// can be updated with subsequent calls to UpdateForwardingPolicy
// targeted at a given ChannelLink concrete interface implementation.
FwrdingPolicy ForwardingPolicy
// Circuits provides restricted access to the switch's circuit map,
// allowing the link to open and close circuits.
Circuits CircuitModifier
// Switch provides a reference to the HTLC switch, we only use this in
// testing to access circuit operations not typically exposed by the
// CircuitModifier.
//
// TODO(conner): remove after refactoring htlcswitch testing framework.
Switch *Switch
// ForwardPackets attempts to forward the batch of htlcs through the
// switch, any failed packets will be returned to the provided
// ChannelLink. The link's quit signal should be provided to allow
// cancellation of forwarding during link shutdown.
ForwardPackets func(chan struct{}, ...*htlcPacket) chan error
// DecodeHopIterators facilitates batched decoding of HTLC Sphinx onion
// blobs, which are then used to inform how to forward an HTLC.
//
// NOTE: This function assumes the same set of readers and preimages
// are always presented for the same identifier.
DecodeHopIterators func([]byte, []DecodeHopIteratorRequest) (
[]DecodeHopIteratorResponse, error)
// ExtractErrorEncrypter function is responsible for decoding HTLC
// Sphinx onion blob, and creating onion failure obfuscator.
ExtractErrorEncrypter ErrorEncrypterExtracter
// FetchLastChannelUpdate retrieves the latest routing policy for a
// target channel. This channel will typically be the outgoing channel
// specified when we receive an incoming HTLC. This will be used to
// provide payment senders our latest policy when sending encrypted
// error messages.
FetchLastChannelUpdate func(lnwire.ShortChannelID) (*lnwire.ChannelUpdate, error)
// Peer is a lightning network node with which we have the channel link
// opened.
Peer lnpeer.Peer
// Registry is a sub-system which responsible for managing the invoices
// in thread-safe manner.
Registry InvoiceDatabase
// PreimageCache is a global witness beacon that houses any new
// preimages discovered by other links. We'll use this to add new
// witnesses that we discover which will notify any sub-systems
// subscribed to new events.
PreimageCache contractcourt.WitnessBeacon
// OnChannelFailure is a function closure that we'll call if the
// channel failed for some reason. Depending on the severity of the
// error, the closure potentially must force close this channel and
// disconnect the peer.
//
// NOTE: The method must return in order for the ChannelLink to be able
// to shut down properly.
OnChannelFailure func(lnwire.ChannelID, lnwire.ShortChannelID,
LinkFailureError)
// UpdateContractSignals is a function closure that we'll use to update
// outside sub-systems with the latest signals for our inner Lightning
// channel. These signals will notify the caller when the channel has
// been closed, or when the set of active HTLC's is updated.
UpdateContractSignals func(*contractcourt.ContractSignals) error
// ChainEvents is an active subscription to the chain watcher for this
// channel to be notified of any on-chain activity related to this
// channel.
ChainEvents *contractcourt.ChainEventSubscription
// FeeEstimator is an instance of a live fee estimator which will be
// used to dynamically regulate the current fee of the commitment
// transaction to ensure timely confirmation.
FeeEstimator lnwallet.FeeEstimator
// hodl.Mask is a bitvector composed of hodl.Flags, specifying breakpoints
// for HTLC forwarding internal to the switch.
//
// NOTE: This should only be used for testing.
HodlMask hodl.Mask
// SyncStates is used to indicate that we need send the channel
// reestablishment message to the remote peer. It should be done if our
// clients have been restarted, or remote peer have been reconnected.
SyncStates bool
// BatchTicker is the ticker that determines the interval that we'll
// use to check the batch to see if there're any updates we should
// flush out. By batching updates into a single commit, we attempt to
// increase throughput by maximizing the number of updates coalesced
// into a single commit.
BatchTicker ticker.Ticker
// FwdPkgGCTicker is the ticker determining the frequency at which
// garbage collection of forwarding packages occurs. We use a
// time-based approach, as opposed to block epochs, as to not hinder
// syncing.
FwdPkgGCTicker ticker.Ticker
// BatchSize is the max size of a batch of updates done to the link
// before we do a state update.
BatchSize uint32
// UnsafeReplay will cause a link to replay the adds in its latest
// commitment txn after the link is restarted. This should only be used
// in testing, it is here to ensure the sphinx replay detection on the
// receiving node is persistent.
UnsafeReplay bool
// MinFeeUpdateTimeout represents the minimum interval in which a link
// will propose to update its commitment fee rate. A random timeout will
// be selected between this and MaxFeeUpdateTimeout.
MinFeeUpdateTimeout time.Duration
// MaxFeeUpdateTimeout represents the maximum interval in which a link
// will propose to update its commitment fee rate. A random timeout will
// be selected between this and MinFeeUpdateTimeout.
MaxFeeUpdateTimeout time.Duration
// OutgoingCltvRejectDelta defines the number of blocks before expiry of
// an htlc where we don't offer an htlc anymore. This should be at least
// the outgoing broadcast delta, because in any case we don't want to
// risk offering an htlc that triggers channel closure.
OutgoingCltvRejectDelta uint32
// TowerClient is an optional engine that manages the signing,
// encrypting, and uploading of justice transactions to the daemon's
// configured set of watchtowers.
TowerClient TowerClient
// MaxCltvExpiry is the maximum outgoing timelock that the link should
// accept for a forwarded HTLC. The value is relative to the current
// block height.
MaxOutgoingCltvExpiry uint32
}
// channelLink is the service which drives a channel's commitment update
// state-machine. In the event that an HTLC needs to be propagated to another
// link, the forward handler from config is used which sends HTLC to the
// switch. Additionally, the link encapsulate logic of commitment protocol
// message ordering and updates.
type channelLink struct {
// The following fields are only meant to be used *atomically*
started int32
shutdown int32
// failed should be set to true in case a link error happens, making
// sure we don't process any more updates.
failed bool
// batchCounter is the number of updates which we received from remote
// side, but not include in commitment transaction yet and plus the
// current number of settles that have been sent, but not yet committed
// to the commitment.
//
// TODO(andrew.shvv) remove after we add additional BatchNumber()
// method in state machine.
batchCounter uint32
// keystoneBatch represents a volatile list of keystones that must be
// written before attempting to sign the next commitment txn. These
// represent all the HTLC's forwarded to the link from the switch. Once
// we lock them into our outgoing commitment, then the circuit has a
// keystone, and is fully opened.
keystoneBatch []Keystone
// openedCircuits is the set of all payment circuits that will be open
// once we make our next commitment. After making the commitment we'll
// ACK all these from our mailbox to ensure that they don't get
// re-delivered if we reconnect.
openedCircuits []CircuitKey
// closedCircuits is the set of all payment circuits that will be
// closed once we make our next commitment. After taking the commitment
// we'll ACK all these to ensure that they don't get re-delivered if we
// reconnect.
closedCircuits []CircuitKey
// channel is a lightning network channel to which we apply htlc
// updates.
channel *lnwallet.LightningChannel
// shortChanID is the most up to date short channel ID for the link.
shortChanID lnwire.ShortChannelID
// cfg is a structure which carries all dependable fields/handlers
// which may affect behaviour of the service.
cfg ChannelLinkConfig
// overflowQueue is used to store the htlc add updates which haven't
// been processed because of the commitment transaction overflow.
overflowQueue *packetQueue
// startMailBox directs whether or not to start the mailbox when
// starting the link. It may have already been started by the switch.
startMailBox bool
// mailBox is the main interface between the outside world and the
// link. All incoming messages will be sent over this mailBox. Messages
// include new updates from our connected peer, and new packets to be
// forwarded sent by the switch.
mailBox MailBox
// upstream is a channel that new messages sent from the remote peer to
// the local peer will be sent across.
upstream chan lnwire.Message
// downstream is a channel in which new multi-hop HTLC's to be
// forwarded will be sent across. Messages from this channel are sent
// by the HTLC switch.
downstream chan *htlcPacket
// htlcUpdates is a channel that we'll use to update outside
// sub-systems with the latest set of active HTLC's on our channel.
htlcUpdates chan *contractcourt.ContractUpdate
// 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 *time.Timer
logCommitTick <-chan time.Time
// updateFeeTimer is the timer responsible for updating the link's
// commitment fee every time it fires.
updateFeeTimer *time.Timer
// uncommittedPreimages stores a list of all preimages that have been
// learned since receiving the last CommitSig from the remote peer. The
// batch will be flushed just before accepting the subsequent CommitSig
// or on shutdown to avoid doing a write for each preimage received.
uncommittedPreimages []lntypes.Preimage
sync.RWMutex
// hodlQueue is used to receive exit hop htlc resolutions from invoice
// registry.
hodlQueue *queue.ConcurrentQueue
// hodlMap stores a list of htlc data structs per hash. It allows
// resolving those htlcs when we receive a message on hodlQueue.
hodlMap map[lntypes.Hash][]hodlHtlc
wg sync.WaitGroup
quit chan struct{}
}
// hodlHtlc contains htlc data that is required for resolution.
type hodlHtlc struct {
pd *lnwallet.PaymentDescriptor
obfuscator ErrorEncrypter
}
// NewChannelLink creates a new instance of a ChannelLink given a configuration
// and active channel that will be used to verify/apply updates to.
func NewChannelLink(cfg ChannelLinkConfig,
channel *lnwallet.LightningChannel) ChannelLink {
return &channelLink{
cfg: cfg,
channel: channel,
shortChanID: channel.ShortChanID(),
// TODO(roasbeef): just do reserve here?
logCommitTimer: time.NewTimer(300 * time.Millisecond),
overflowQueue: newPacketQueue(input.MaxHTLCNumber / 2),
htlcUpdates: make(chan *contractcourt.ContractUpdate),
hodlMap: make(map[lntypes.Hash][]hodlHtlc),
hodlQueue: queue.NewConcurrentQueue(10),
quit: make(chan struct{}),
}
}
// A compile time check to ensure channelLink implements the ChannelLink
// interface.
var _ ChannelLink = (*channelLink)(nil)
// Start starts all helper goroutines required for the operation of the channel
// link.
//
// NOTE: Part of the ChannelLink interface.
func (l *channelLink) Start() error {
if !atomic.CompareAndSwapInt32(&l.started, 0, 1) {
err := errors.Errorf("channel link(%v): already started", l)
log.Warn(err)
return err
}
log.Infof("ChannelLink(%v) is starting", l)
// If the config supplied watchtower client, ensure the channel is
// registered before trying to use it during operation.
if l.cfg.TowerClient != nil {
err := l.cfg.TowerClient.RegisterChannel(l.ChanID())
if err != nil {
return err
}
}
l.mailBox.ResetMessages()
l.overflowQueue.Start()
l.hodlQueue.Start()
// Before launching the htlcManager messages, revert any circuits that
// were marked open in the switch's circuit map, but did not make it
// into a commitment txn. We use the next local htlc index as the cut
// off point, since all indexes below that are committed. This action
// is only performed if the link's final short channel ID has been
// assigned, otherwise we would try to trim the htlcs belonging to the
// all-zero, sourceHop ID.
if l.ShortChanID() != sourceHop {
localHtlcIndex, err := l.channel.NextLocalHtlcIndex()
if err != nil {
return fmt.Errorf("unable to retrieve next local "+
"htlc index: %v", err)
}
// NOTE: This is automatically done by the switch when it
// starts up, but is necessary to prevent inconsistencies in
// the case that the link flaps. This is a result of a link's
// life-cycle being shorter than that of the switch.
chanID := l.ShortChanID()
err = l.cfg.Circuits.TrimOpenCircuits(chanID, localHtlcIndex)
if err != nil {
return fmt.Errorf("unable to trim circuits above "+
"local htlc index %d: %v", localHtlcIndex, err)
}
// Since the link is live, before we start the link we'll update
// the ChainArbitrator with the set of new channel signals for
// this channel.
//
// TODO(roasbeef): split goroutines within channel arb to avoid
go func() {
signals := &contractcourt.ContractSignals{
HtlcUpdates: l.htlcUpdates,
ShortChanID: l.channel.ShortChanID(),
}
err := l.cfg.UpdateContractSignals(signals)
if err != nil {
log.Errorf("Unable to update signals for "+
"ChannelLink(%v)", l)
}
}()
}
l.updateFeeTimer = time.NewTimer(l.randomFeeUpdateTimeout())
l.wg.Add(1)
go l.htlcManager()
return nil
}
// Stop gracefully stops all active helper goroutines, then waits until they've
// exited.
//
// NOTE: Part of the ChannelLink interface.
func (l *channelLink) Stop() {
if !atomic.CompareAndSwapInt32(&l.shutdown, 0, 1) {
log.Warnf("channel link(%v): already stopped", l)
return
}
log.Infof("ChannelLink(%v) is stopping", l)
// As the link is stopping, we are no longer interested in hodl events
// coming from the invoice registry.
l.cfg.Registry.HodlUnsubscribeAll(l.hodlQueue.ChanIn())
if l.cfg.ChainEvents.Cancel != nil {
l.cfg.ChainEvents.Cancel()
}
l.updateFeeTimer.Stop()
l.overflowQueue.Stop()
l.hodlQueue.Stop()
close(l.quit)
l.wg.Wait()
// As a final precaution, we will attempt to flush any uncommitted
// preimages to the preimage cache. The preimages should be re-delivered
// after channel reestablishment, however this adds an extra layer of
// protection in case the peer never returns. Without this, we will be
// unable to settle any contracts depending on the preimages even though
// we had learned them at some point.
err := l.cfg.PreimageCache.AddPreimages(l.uncommittedPreimages...)
if err != nil {
log.Errorf("Unable to add preimages=%v to cache: %v",
l.uncommittedPreimages, err)
}
}
// WaitForShutdown blocks until the link finishes shutting down, which includes
// termination of all dependent goroutines.
func (l *channelLink) WaitForShutdown() {
l.wg.Wait()
}
// EligibleToForward returns a bool indicating if the channel is able to
// actively accept requests to forward HTLC's. We're able to forward HTLC's if
// we know the remote party's next revocation point. Otherwise, we can't
// initiate new channel state. We also require that the short channel ID not be
// the all-zero source ID, meaning that the channel has had its ID finalized.
func (l *channelLink) EligibleToForward() bool {
return l.channel.RemoteNextRevocation() != nil &&
l.ShortChanID() != sourceHop
}
// sampleNetworkFee samples the current fee rate on the network to get into the
// chain in a timely manner. The returned value is expressed in fee-per-kw, as
// this is the native rate used when computing the fee for commitment
// transactions, and the second-level HTLC transactions.
func (l *channelLink) sampleNetworkFee() (lnwallet.SatPerKWeight, error) {
// We'll first query for the sat/kw recommended to be confirmed within 3
// blocks.
feePerKw, err := l.cfg.FeeEstimator.EstimateFeePerKW(3)
if err != nil {
return 0, err
}
log.Debugf("ChannelLink(%v): sampled fee rate for 3 block conf: %v "+
"sat/kw", l, int64(feePerKw))
return feePerKw, nil
}
// shouldAdjustCommitFee returns true if we should update our commitment fee to
// match that of the network fee. We'll only update our commitment fee if the
// network fee is +/- 10% to our network fee.
func shouldAdjustCommitFee(netFee, chanFee lnwallet.SatPerKWeight) bool {
switch {
// If the network fee is greater than the commitment fee, then we'll
// switch to it if it's at least 10% greater than the commit fee.
case netFee > chanFee && netFee >= (chanFee+(chanFee*10)/100):
return true
// If the network fee is less than our commitment fee, then we'll
// switch to it if it's at least 10% less than the commitment fee.
case netFee < chanFee && netFee <= (chanFee-(chanFee*10)/100):
return true
// Otherwise, we won't modify our fee.
default:
return false
}
}
// syncChanState attempts to synchronize channel states with the remote party.
// This method is to be called upon reconnection after the initial funding
// flow. We'll compare out commitment chains with the remote party, and re-send
// either a danging commit signature, a revocation, or both.
func (l *channelLink) syncChanStates() error {
log.Infof("Attempting to re-resynchronize ChannelPoint(%v)",
l.channel.ChannelPoint())
// First, we'll generate our ChanSync message to send to the other
// side. Based on this message, the remote party will decide if they
// need to retransmit any data or not.
chanState := l.channel.State()
localChanSyncMsg, err := lnwallet.ChanSyncMsg(
chanState,
chanState.HasChanStatus(channeldb.ChanStatusRestored),
)
if err != nil {
return fmt.Errorf("unable to generate chan sync message for "+
"ChannelPoint(%v)", l.channel.ChannelPoint())
}
// If we have a restored channel, we'll delay sending our channel
// reestablish message briefly to ensure we first have a stable
// connection. Sending the message will cause the remote peer to force
// close the channel, which currently may not be resumed reliably if the
// connection is being torn down simultaneously. This delay can be
// removed after the force close is reliable, but in the meantime it
// improves the reliability of successfully closing out the channel.
if chanState.HasChanStatus(channeldb.ChanStatusRestored) {
select {
case <-time.After(5 * time.Second):
case <-l.quit:
return ErrLinkShuttingDown
}
}
if err := l.cfg.Peer.SendMessage(true, localChanSyncMsg); err != nil {
return fmt.Errorf("Unable to send chan sync message for "+
"ChannelPoint(%v)", l.channel.ChannelPoint())
}
var msgsToReSend []lnwire.Message
// Next, we'll wait to receive the ChanSync message with a timeout
// period. The first message sent MUST be the ChanSync message,
// otherwise, we'll terminate the connection.
chanSyncDeadline := time.After(time.Second * 30)
select {
case msg := <-l.upstream:
remoteChanSyncMsg, ok := msg.(*lnwire.ChannelReestablish)
if !ok {
return fmt.Errorf("first message sent to sync "+
"should be ChannelReestablish, instead "+
"received: %T", msg)
}
// If the remote party indicates that they think we haven't
// done any state updates yet, then we'll retransmit the
// funding locked message first. We do this, as at this point
// we can't be sure if they've really received the
// FundingLocked message.
if remoteChanSyncMsg.NextLocalCommitHeight == 1 &&
localChanSyncMsg.NextLocalCommitHeight == 1 &&
!l.channel.IsPending() {
log.Infof("ChannelPoint(%v): resending "+
"FundingLocked message to peer",
l.channel.ChannelPoint())
nextRevocation, err := l.channel.NextRevocationKey()
if err != nil {
return fmt.Errorf("unable to create next "+
"revocation: %v", err)
}
fundingLockedMsg := lnwire.NewFundingLocked(
l.ChanID(), nextRevocation,
)
err = l.cfg.Peer.SendMessage(false, fundingLockedMsg)
if err != nil {
return fmt.Errorf("unable to re-send "+
"FundingLocked: %v", err)
}
}
// In any case, we'll then process their ChanSync message.
log.Infof("Received re-establishment message from remote side "+
"for channel(%v)", l.channel.ChannelPoint())
var (
openedCircuits []CircuitKey
closedCircuits []CircuitKey
)
// We've just received a ChanSync message from the remote
// party, so we'll process the message in order to determine
// if we need to re-transmit any messages to the remote party.
msgsToReSend, openedCircuits, closedCircuits, err =
l.channel.ProcessChanSyncMsg(remoteChanSyncMsg)
if err != nil {
return err
}
// Repopulate any identifiers for circuits that may have been
// opened or unclosed. This may happen if we needed to
// retransmit a commitment signature message.
l.openedCircuits = openedCircuits
l.closedCircuits = closedCircuits
// Ensure that all packets have been have been removed from the
// link's mailbox.
if err := l.ackDownStreamPackets(); err != nil {
return err
}
if len(msgsToReSend) > 0 {
log.Infof("Sending %v updates to synchronize the "+
"state for ChannelPoint(%v)", len(msgsToReSend),
l.channel.ChannelPoint())
}
// If we have any messages to retransmit, we'll do so
// immediately so we return to a synchronized state as soon as
// possible.
for _, msg := range msgsToReSend {
l.cfg.Peer.SendMessage(false, msg)
}
case <-l.quit:
return ErrLinkShuttingDown
case <-chanSyncDeadline:
return fmt.Errorf("didn't receive ChannelReestablish before " +
"deadline")
}
return nil
}
// resolveFwdPkgs loads any forwarding packages for this link from disk, and
// reprocesses them in order. The primary goal is to make sure that any HTLCs
// we previously received are reinstated in memory, and forwarded to the switch
// if necessary. After a restart, this will also delete any previously
// completed packages.
func (l *channelLink) resolveFwdPkgs() error {
fwdPkgs, err := l.channel.LoadFwdPkgs()
if err != nil {
return err
}
l.debugf("loaded %d fwd pks", len(fwdPkgs))
var needUpdate bool
for _, fwdPkg := range fwdPkgs {
hasUpdate, err := l.resolveFwdPkg(fwdPkg)
if err != nil {
return err
}
needUpdate = needUpdate || hasUpdate
}
// If any of our reprocessing steps require an update to the commitment
// txn, we initiate a state transition to capture all relevant changes.
if needUpdate {
return l.updateCommitTx()
}
return nil
}
// resolveFwdPkg interprets the FwdState of the provided package, either
// reprocesses any outstanding htlcs in the package, or performs garbage
// collection on the package.
func (l *channelLink) resolveFwdPkg(fwdPkg *channeldb.FwdPkg) (bool, error) {
// Remove any completed packages to clear up space.
if fwdPkg.State == channeldb.FwdStateCompleted {
l.debugf("removing completed fwd pkg for height=%d",
fwdPkg.Height)
err := l.channel.RemoveFwdPkg(fwdPkg.Height)
if err != nil {
l.errorf("unable to remove fwd pkg for height=%d: %v",
fwdPkg.Height, err)
return false, err
}
}
// Otherwise this is either a new package or one has gone through
// processing, but contains htlcs that need to be restored in memory.
// We replay this forwarding package to make sure our local mem state
// is resurrected, we mimic any original responses back to the remote
// party, and re-forward the relevant HTLCs to the switch.
// If the package is fully acked but not completed, it must still have
// settles and fails to propagate.
if !fwdPkg.SettleFailFilter.IsFull() {
settleFails, err := lnwallet.PayDescsFromRemoteLogUpdates(
fwdPkg.Source, fwdPkg.Height, fwdPkg.SettleFails,
)
if err != nil {
l.errorf("Unable to process remote log updates: %v",
err)
return false, err
}
l.processRemoteSettleFails(fwdPkg, settleFails)
}
// Finally, replay *ALL ADDS* in this forwarding package. The
// downstream logic is able to filter out any duplicates, but we must
// shove the entire, original set of adds down the pipeline so that the
// batch of adds presented to the sphinx router does not ever change.
var needUpdate bool
if !fwdPkg.AckFilter.IsFull() {
adds, err := lnwallet.PayDescsFromRemoteLogUpdates(
fwdPkg.Source, fwdPkg.Height, fwdPkg.Adds,
)
if err != nil {
l.errorf("Unable to process remote log updates: %v",
err)
return false, err
}
needUpdate = l.processRemoteAdds(fwdPkg, adds)
// If the link failed during processing the adds, we must
// return to ensure we won't attempted to update the state
// further.
if l.failed {
return false, fmt.Errorf("link failed while " +
"processing remote adds")
}
}
return needUpdate, nil
}
// fwdPkgGarbager periodically reads all forwarding packages from disk and
// removes those that can be discarded. It is safe to do this entirely in the
// background, since all state is coordinated on disk. This also ensures the
// link can continue to process messages and interleave database accesses.
//
// NOTE: This MUST be run as a goroutine.
func (l *channelLink) fwdPkgGarbager() {
defer l.wg.Done()
l.cfg.FwdPkgGCTicker.Resume()
defer l.cfg.FwdPkgGCTicker.Stop()
for {
select {
case <-l.cfg.FwdPkgGCTicker.Ticks():
fwdPkgs, err := l.channel.LoadFwdPkgs()
if err != nil {
l.warnf("unable to load fwdpkgs for gc: %v", err)
continue
}
// TODO(conner): batch removal of forward packages.
for _, fwdPkg := range fwdPkgs {
if fwdPkg.State != channeldb.FwdStateCompleted {
continue
}
err = l.channel.RemoveFwdPkg(fwdPkg.Height)
if err != nil {
l.warnf("unable to remove fwd pkg "+
"for height=%d: %v",
fwdPkg.Height, err)
}
}
case <-l.quit:
return
}
}
}
// htlcManager is the primary goroutine which drives a channel's commitment
// update state-machine in response to messages received via several channels.
// This goroutine reads messages from the upstream (remote) peer, and also from
// downstream channel managed by the channel link. In the event that an htlc
// needs to be forwarded, then send-only forward handler is used which sends
// htlc packets to the switch. Additionally, the this goroutine handles acting
// upon all timeouts for any active HTLCs, manages the channel's revocation
// window, and also the htlc trickle queue+timer for this active channels.
//
// NOTE: This MUST be run as a goroutine.
func (l *channelLink) htlcManager() {
defer func() {
l.cfg.BatchTicker.Stop()
l.wg.Done()
log.Infof("ChannelLink(%v) has exited", l)
}()
log.Infof("HTLC manager for ChannelPoint(%v) started, "+
"bandwidth=%v", l.channel.ChannelPoint(), l.Bandwidth())
// TODO(roasbeef): need to call wipe chan whenever D/C?
// If this isn't the first time that this channel link has been
// created, then we'll need to check to see if we need to
// re-synchronize state with the remote peer. settledHtlcs is a map of
// HTLC's that we re-settled as part of the channel state sync.
if l.cfg.SyncStates {
err := l.syncChanStates()
if err != nil {
switch {
case err == ErrLinkShuttingDown:
log.Debugf("unable to sync channel states, " +
"link is shutting down")
return
// We failed syncing the commit chains, probably
// because the remote has lost state. We should force
// close the channel.
case err == lnwallet.ErrCommitSyncRemoteDataLoss:
fallthrough
// The remote sent us an invalid last commit secret, we
// should force close the channel.
// TODO(halseth): and permanently ban the peer?
case err == lnwallet.ErrInvalidLastCommitSecret:
fallthrough
// The remote sent us a commit point different from
// what they sent us before.
// TODO(halseth): ban peer?
case err == lnwallet.ErrInvalidLocalUnrevokedCommitPoint:
l.fail(
LinkFailureError{
code: ErrSyncError,
ForceClose: true,
},
"unable to synchronize channel "+
"states: %v", err,
)
return
// We have lost state and cannot safely force close the
// channel. Fail the channel and wait for the remote to
// hopefully force close it. The remote has sent us its
// latest unrevoked commitment point, that we stored in
// the database, that we can use to retrieve the funds
// when the remote closes the channel.
// TODO(halseth): mark this, such that we prevent
// channel from being force closed by the user or
// contractcourt etc.
case err == lnwallet.ErrCommitSyncLocalDataLoss:
// We determined the commit chains were not possible to
// sync. We cautiously fail the channel, but don't
// force close.
// TODO(halseth): can we safely force close in any
// cases where this error is returned?
case err == lnwallet.ErrCannotSyncCommitChains:
// Other, unspecified error.
default:
}
l.fail(
LinkFailureError{
code: ErrSyncError,
ForceClose: false,
},
"unable to synchronize channel "+
"states: %v", err,
)
return
}
}
// With the channel states synced, we now reset the mailbox to ensure
// we start processing all unacked packets in order. This is done here
// to ensure that all acknowledgments that occur during channel
// resynchronization have taken affect, causing us only to pull unacked
// packets after starting to read from the downstream mailbox.
l.mailBox.ResetPackets()
// After cleaning up any memory pertaining to incoming packets, we now
// replay our forwarding packages to handle any htlcs that can be
// processed locally, or need to be forwarded out to the switch. We will
// only attempt to resolve packages if our short chan id indicates that
// the channel is not pending, otherwise we should have no htlcs to
// reforward.
if l.ShortChanID() != sourceHop {
if err := l.resolveFwdPkgs(); err != nil {
l.fail(LinkFailureError{code: ErrInternalError},
"unable to resolve fwd pkgs: %v", err)
return
}
// With our link's in-memory state fully reconstructed, spawn a
// goroutine to manage the reclamation of disk space occupied by
// completed forwarding packages.
l.wg.Add(1)
go l.fwdPkgGarbager()
}
out:
for {
// We must always check if we failed at some point processing
// the last update before processing the next.
if l.failed {
l.errorf("link failed, exiting htlcManager")
break out
}
// If the previous event resulted in a non-empty
// batch, reinstate the batch ticker so that it can be
// cleared.
if l.batchCounter > 0 {
l.cfg.BatchTicker.Resume()
}
select {
// Our update fee timer has fired, so we'll check the network
// fee to see if we should adjust our commitment fee.
case <-l.updateFeeTimer.C:
l.updateFeeTimer.Reset(l.randomFeeUpdateTimeout())
// If we're not the initiator of the channel, don't we
// don't control the fees, so we can ignore this.
if !l.channel.IsInitiator() {
continue
}
// If we are the initiator, then we'll sample the
// current fee rate to get into the chain within 3
// blocks.
feePerKw, err := l.sampleNetworkFee()
if err != nil {
log.Errorf("unable to sample network fee: %v", err)
continue
}
// We'll check to see if we should update the fee rate
// based on our current set fee rate.
commitFee := l.channel.CommitFeeRate()
if !shouldAdjustCommitFee(feePerKw, commitFee) {
continue
}
// If we do, then we'll send a new UpdateFee message to
// the remote party, to be locked in with a new update.
if err := l.updateChannelFee(feePerKw); err != nil {
log.Errorf("unable to update fee rate: %v", err)
continue
}
// The underlying channel has notified us of a unilateral close
// carried out by the remote peer. In the case of such an
// event, we'll wipe the channel state from the peer, and mark
// the contract as fully settled. Afterwards we can exit.
//
// TODO(roasbeef): add force closure? also breach?
case <-l.cfg.ChainEvents.RemoteUnilateralClosure:
log.Warnf("Remote peer has closed ChannelPoint(%v) on-chain",
l.channel.ChannelPoint())
// TODO(roasbeef): remove all together
go func() {
chanPoint := l.channel.ChannelPoint()
err := l.cfg.Peer.WipeChannel(chanPoint)
if err != nil {
log.Errorf("unable to wipe channel %v", err)
}
}()
break out
case <-l.logCommitTick:
// 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 due to our
// commitment chains being desynchronized.
if l.channel.FullySynced() {
continue
}
if err := l.updateCommitTx(); err != nil {
l.fail(LinkFailureError{code: ErrInternalError},
"unable to update commitment: %v", err)
break out
}
case <-l.cfg.BatchTicker.Ticks():
// If the current batch is empty, then we have no work
// here. We also disable the batch ticker from waking up
// the htlcManager while the batch is empty.
if l.batchCounter == 0 {
l.cfg.BatchTicker.Pause()
continue
}
// Otherwise, attempt to extend the remote commitment
// chain including all the currently pending entries.
// If the send was unsuccessful, then abandon the
// update, waiting for the revocation window to open
// up.
if err := l.updateCommitTx(); err != nil {
l.fail(LinkFailureError{code: ErrInternalError},
"unable to update commitment: %v", err)
break out
}
// A packet that previously overflowed the commitment
// transaction is now eligible for processing once again. So
// we'll attempt to re-process the packet in order to allow it
// to continue propagating within the network.
case packet := <-l.overflowQueue.outgoingPkts:
msg := packet.htlc.(*lnwire.UpdateAddHTLC)
log.Tracef("Reprocessing downstream add update "+
"with payment hash(%x)", msg.PaymentHash[:])
l.handleDownStreamPkt(packet, true)
// A message from the switch was just received. This indicates
// that the link is an intermediate hop in a multi-hop HTLC
// circuit.
case pkt := <-l.downstream:
// If we have non empty processing queue then we'll add
// this to the overflow rather than processing it
// directly. Once an active HTLC is either settled or
// failed, then we'll free up a new slot.
htlc, ok := pkt.htlc.(*lnwire.UpdateAddHTLC)
if ok && l.overflowQueue.Length() != 0 {
log.Infof("Downstream htlc add update with "+
"payment hash(%x) have been added to "+
"reprocessing queue, batch_size=%v",
htlc.PaymentHash[:],
l.batchCounter)
l.overflowQueue.AddPkt(pkt)
continue
}
l.handleDownStreamPkt(pkt, false)
// A message from the connected peer was just received. This
// indicates that we have a new incoming HTLC, either directly
// for us, or part of a multi-hop HTLC circuit.
case msg := <-l.upstream:
l.handleUpstreamMsg(msg)
// A hodl event is received. This means that we now have a
// resolution for a previously accepted htlc.
case hodlItem := <-l.hodlQueue.ChanOut():
hodlEvent := hodlItem.(invoices.HodlEvent)
err := l.processHodlQueue(hodlEvent)
if err != nil {
l.fail(LinkFailureError{code: ErrInternalError},
fmt.Sprintf("process hodl queue: %v",
err.Error()),
)
break out
}
case <-l.quit:
break out
}
}
}
// processHodlQueue processes a received hodl event and continues reading from
// the hodl queue until no more events remain. When this function returns
// without an error, the commit tx should be updated.
func (l *channelLink) processHodlQueue(firstHodlEvent invoices.HodlEvent) error {
// Try to read all waiting resolution messages, so that they can all be
// processed in a single commitment tx update.
hodlEvent := firstHodlEvent
loop:
for {
if err := l.processHodlMapEvent(hodlEvent); err != nil {
return err
}
select {
case item := <-l.hodlQueue.ChanOut():
hodlEvent = item.(invoices.HodlEvent)
default:
break loop
}
}
// Update the commitment tx.
if err := l.updateCommitTx(); err != nil {
return fmt.Errorf("unable to update commitment: %v", err)
}
return nil
}
// processHodlMapEvent resolves stored hodl htlcs based using the information in
// hodlEvent.
func (l *channelLink) processHodlMapEvent(hodlEvent invoices.HodlEvent) error {
// Lookup all hodl htlcs that can be failed or settled with this event.
// The hodl htlc must be present in the map.
hash := hodlEvent.Hash
hodlHtlcs, ok := l.hodlMap[hash]
if !ok {
return fmt.Errorf("hodl htlc not found: %v", hash)
}
if err := l.processHodlEvent(hodlEvent, hodlHtlcs...); err != nil {
return err
}
// Clean up hodl map.
delete(l.hodlMap, hash)
return nil
}
// processHodlEvent applies a received hodl event to the provided htlc. When
// this function returns without an error, the commit tx should be updated.
func (l *channelLink) processHodlEvent(hodlEvent invoices.HodlEvent,
htlcs ...hodlHtlc) error {
hash := hodlEvent.Hash
// Determine required action for the resolution.
var hodlAction func(htlc hodlHtlc) error
if hodlEvent.Preimage != nil {
l.debugf("Received hodl settle event for %v", hash)
hodlAction = func(htlc hodlHtlc) error {
return l.settleHTLC(
*hodlEvent.Preimage, htlc.pd.HtlcIndex,
htlc.pd.SourceRef,
)
}
} else {
l.debugf("Received hodl cancel event for %v", hash)
hodlAction = func(htlc hodlHtlc) error {
// In case of a cancel, always return
// incorrect_or_unknown_payment_details in order to
// avoid leaking info.
failure := lnwire.NewFailIncorrectDetails(
htlc.pd.Amount,
)
l.sendHTLCError(
htlc.pd.HtlcIndex, failure, htlc.obfuscator,
htlc.pd.SourceRef,
)
return nil
}
}
// Apply action for all htlcs matching this hash.
for _, htlc := range htlcs {
if err := hodlAction(htlc); err != nil {
return err
}
l.batchCounter++
}
return nil
}
// randomFeeUpdateTimeout returns a random timeout between the bounds defined
// within the link's configuration that will be used to determine when the link
// should propose an update to its commitment fee rate.
func (l *channelLink) randomFeeUpdateTimeout() time.Duration {
lower := int64(l.cfg.MinFeeUpdateTimeout)
upper := int64(l.cfg.MaxFeeUpdateTimeout)
return time.Duration(prand.Int63n(upper-lower) + lower)
}
// handleDownStreamPkt processes an HTLC packet sent from the downstream HTLC
// Switch. Possible messages sent by the switch include requests to forward new
// HTLCs, timeout previously cleared HTLCs, and finally to settle currently
// cleared HTLCs with the upstream peer.
//
// TODO(roasbeef): add sync ntfn to ensure switch always has consistent view?
func (l *channelLink) handleDownStreamPkt(pkt *htlcPacket, isReProcess bool) {
var isSettle bool
switch htlc := pkt.htlc.(type) {
case *lnwire.UpdateAddHTLC:
// If hodl.AddOutgoing mode is active, we exit early to simulate
// arbitrary delays between the switch adding an ADD to the
// mailbox, and the HTLC being added to the commitment state.
if l.cfg.HodlMask.Active(hodl.AddOutgoing) {
l.warnf(hodl.AddOutgoing.Warning())
l.mailBox.AckPacket(pkt.inKey())
return
}
// 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.
htlc.ChanID = l.ChanID()
openCircuitRef := pkt.inKey()
index, err := l.channel.AddHTLC(htlc, &openCircuitRef)
if err != nil {
switch err {
// The channels spare bandwidth is fully allocated, so
// we'll put this HTLC into the overflow queue.
case lnwallet.ErrMaxHTLCNumber:
l.infof("Downstream htlc add update with "+
"payment hash(%x) have been added to "+
"reprocessing queue, batch: %v",
htlc.PaymentHash[:],
l.batchCounter)
l.overflowQueue.AddPkt(pkt)
return
// The HTLC was unable to be added to the state
// machine, as a result, we'll signal the switch to
// cancel the pending payment.
default:
l.warnf("Unable to handle downstream add HTLC: %v", err)
var (
localFailure = false
reason lnwire.OpaqueReason
)
var failure lnwire.FailureMessage
update, err := l.cfg.FetchLastChannelUpdate(
l.ShortChanID(),
)
if err != nil {
failure = &lnwire.FailTemporaryNodeFailure{}
} else {
failure = lnwire.NewTemporaryChannelFailure(
update,
)
}
// Encrypt the error back to the source unless
// the payment was generated locally.
if pkt.obfuscator == nil {
var b bytes.Buffer
err := lnwire.EncodeFailure(&b, failure, 0)
if err != nil {
l.errorf("unable to encode failure: %v", err)
l.mailBox.AckPacket(pkt.inKey())
return
}
reason = lnwire.OpaqueReason(b.Bytes())
localFailure = true
} else {
var err error
reason, err = pkt.obfuscator.EncryptFirstHop(failure)
if err != nil {
l.errorf("unable to obfuscate error: %v", err)
l.mailBox.AckPacket(pkt.inKey())
return
}
}
failPkt := &htlcPacket{
incomingChanID: pkt.incomingChanID,
incomingHTLCID: pkt.incomingHTLCID,
circuit: pkt.circuit,
sourceRef: pkt.sourceRef,
hasSource: true,
localFailure: localFailure,
htlc: &lnwire.UpdateFailHTLC{
Reason: reason,
},
}
go l.forwardBatch(failPkt)
// Remove this packet from the link's mailbox,
// this prevents it from being reprocessed if
// the link restarts and resets it mailbox. If
// this response doesn't make it back to the
// originating link, it will be rejected upon
// attempting to reforward the Add to the
// switch, since the circuit was never fully
// opened, and the forwarding package shows it
// as unacknowledged.
l.mailBox.AckPacket(pkt.inKey())
return
}
}
l.tracef("Received downstream htlc: payment_hash=%x, "+
"local_log_index=%v, batch_size=%v",
htlc.PaymentHash[:], index, l.batchCounter+1)
pkt.outgoingChanID = l.ShortChanID()
pkt.outgoingHTLCID = index
htlc.ID = index
l.debugf("Queueing keystone of ADD open circuit: %s->%s",
pkt.inKey(), pkt.outKey())
l.openedCircuits = append(l.openedCircuits, pkt.inKey())
l.keystoneBatch = append(l.keystoneBatch, pkt.keystone())
l.cfg.Peer.SendMessage(false, htlc)
case *lnwire.UpdateFulfillHTLC:
// If hodl.SettleOutgoing mode is active, we exit early to
// simulate arbitrary delays between the switch adding the
// SETTLE to the mailbox, and the HTLC being added to the
// commitment state.
if l.cfg.HodlMask.Active(hodl.SettleOutgoing) {
l.warnf(hodl.SettleOutgoing.Warning())
l.mailBox.AckPacket(pkt.inKey())
return
}
// An HTLC we forward to the switch has just settled somewhere
// upstream. Therefore we settle the HTLC within the our local
// state machine.
inKey := pkt.inKey()
err := l.channel.SettleHTLC(
htlc.PaymentPreimage,
pkt.incomingHTLCID,
pkt.sourceRef,
pkt.destRef,
&inKey,
)
if err != nil {
l.errorf("unable to settle incoming HTLC for "+
"circuit-key=%v: %v", inKey, err)
// If the HTLC index for Settle response was not known
// to our commitment state, it has already been
// cleaned up by a prior response. We'll thus try to
// clean up any lingering state to ensure we don't
// continue reforwarding.
if _, ok := err.(lnwallet.ErrUnknownHtlcIndex); ok {
l.cleanupSpuriousResponse(pkt)
}
// Remove the packet from the link's mailbox to ensure
// it doesn't get replayed after a reconnection.
l.mailBox.AckPacket(inKey)
return
}
l.debugf("Queueing removal of SETTLE closed circuit: %s->%s",
pkt.inKey(), pkt.outKey())
l.closedCircuits = append(l.closedCircuits, pkt.inKey())
// With the HTLC settled, we'll need to populate the wire
// message to target the specific channel and HTLC to be
// cancelled.
htlc.ChanID = l.ChanID()
htlc.ID = pkt.incomingHTLCID
// Then we send the HTLC settle message to the connected peer
// so we can continue the propagation of the settle message.
l.cfg.Peer.SendMessage(false, htlc)
isSettle = true
case *lnwire.UpdateFailHTLC:
// If hodl.FailOutgoing mode is active, we exit early to
// simulate arbitrary delays between the switch adding a FAIL to
// the mailbox, and the HTLC being added to the commitment
// state.
if l.cfg.HodlMask.Active(hodl.FailOutgoing) {
l.warnf(hodl.FailOutgoing.Warning())
l.mailBox.AckPacket(pkt.inKey())
return
}
// An HTLC cancellation has been triggered somewhere upstream,
// we'll remove then HTLC from our local state machine.
inKey := pkt.inKey()
err := l.channel.FailHTLC(
pkt.incomingHTLCID,
htlc.Reason,
pkt.sourceRef,
pkt.destRef,
&inKey,
)
if err != nil {
l.errorf("unable to cancel incoming HTLC for "+
"circuit-key=%v: %v", inKey, err)
// If the HTLC index for Fail response was not known to
// our commitment state, it has already been cleaned up
// by a prior response. We'll thus try to clean up any
// lingering state to ensure we don't continue
// reforwarding.
if _, ok := err.(lnwallet.ErrUnknownHtlcIndex); ok {
l.cleanupSpuriousResponse(pkt)
}
// Remove the packet from the link's mailbox to ensure
// it doesn't get replayed after a reconnection.
l.mailBox.AckPacket(inKey)
return
}
l.debugf("Queueing removal of FAIL closed circuit: %s->%s",
pkt.inKey(), pkt.outKey())
l.closedCircuits = append(l.closedCircuits, pkt.inKey())
// With the HTLC removed, we'll need to populate the wire
// message to target the specific channel and HTLC to be
// cancelled. The "Reason" field will have already been set
// within the switch.
htlc.ChanID = l.ChanID()
htlc.ID = pkt.incomingHTLCID
// Finally, we send the HTLC message to the peer which
// initially created the HTLC.
l.cfg.Peer.SendMessage(false, htlc)
isSettle = true
}
l.batchCounter++
// If this newly added update exceeds the min batch size for adds, or
// this is a settle request, then initiate an update.
if l.batchCounter >= l.cfg.BatchSize || isSettle {
if err := l.updateCommitTx(); err != nil {
l.fail(LinkFailureError{code: ErrInternalError},
"unable to update commitment: %v", err)
return
}
}
}
// cleanupSpuriousResponse attempts to ack any AddRef or SettleFailRef
// associated with this packet. If successful in doing so, it will also purge
// the open circuit from the circuit map and remove the packet from the link's
// mailbox.
func (l *channelLink) cleanupSpuriousResponse(pkt *htlcPacket) {
inKey := pkt.inKey()
l.debugf("Cleaning up spurious response for incoming circuit-key=%v",
inKey)
// If the htlc packet doesn't have a source reference, it is unsafe to
// proceed, as skipping this ack may cause the htlc to be reforwarded.
if pkt.sourceRef == nil {
l.errorf("uanble to cleanup response for incoming "+
"circuit-key=%v, does not contain source reference",
inKey)
return
}
// If the source reference is present, we will try to prevent this link
// from resending the packet to the switch. To do so, we ack the AddRef
// of the incoming HTLC belonging to this link.
err := l.channel.AckAddHtlcs(*pkt.sourceRef)
if err != nil {
l.errorf("unable to ack AddRef for incoming "+
"circuit-key=%v: %v", inKey, err)
// If this operation failed, it is unsafe to attempt removal of
// the destination reference or circuit, so we exit early. The
// cleanup may proceed with a different packet in the future
// that succeeds on this step.
return
}
// Now that we know this link will stop retransmitting Adds to the
// switch, we can begin to teardown the response reference and circuit
// map.
//
// If the packet includes a destination reference, then a response for
// this HTLC was locked into the outgoing channel. Attempt to remove
// this reference, so we stop retransmitting the response internally.
// Even if this fails, we will proceed in trying to delete the circuit.
// When retransmitting responses, the destination references will be
// cleaned up if an open circuit is not found in the circuit map.
if pkt.destRef != nil {
err := l.channel.AckSettleFails(*pkt.destRef)
if err != nil {
l.errorf("unable to ack SettleFailRef "+
"for incoming circuit-key=%v: %v",
inKey, err)
}
}
l.debugf("Deleting circuit for incoming circuit-key=%x", inKey)
// With all known references acked, we can now safely delete the circuit
// from the switch's circuit map, as the state is no longer needed.
err = l.cfg.Circuits.DeleteCircuits(inKey)
if err != nil {
l.errorf("unable to delete circuit for "+
"circuit-key=%v: %v", inKey, err)
}
}
// 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 (l *channelLink) handleUpstreamMsg(msg lnwire.Message) {
switch msg := msg.(type) {
case *lnwire.UpdateAddHTLC:
// 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 preimage.
index, err := l.channel.ReceiveHTLC(msg)
if err != nil {
l.fail(LinkFailureError{code: ErrInvalidUpdate},
"unable to handle upstream add HTLC: %v", err)
return
}
l.tracef("Receive upstream htlc with payment hash(%x), "+
"assigning index: %v", msg.PaymentHash[:], index)
case *lnwire.UpdateFulfillHTLC:
pre := msg.PaymentPreimage
idx := msg.ID
if err := l.channel.ReceiveHTLCSettle(pre, idx); err != nil {
l.fail(
LinkFailureError{
code: ErrInvalidUpdate,
ForceClose: true,
},
"unable to handle upstream settle HTLC: %v", err,
)
return
}
settlePacket := &htlcPacket{
outgoingChanID: l.ShortChanID(),
outgoingHTLCID: idx,
htlc: &lnwire.UpdateFulfillHTLC{
PaymentPreimage: pre,
},
}
// Add the newly discovered preimage to our growing list of
// uncommitted preimage. These will be written to the witness
// cache just before accepting the next commitment signature
// from the remote peer.
l.uncommittedPreimages = append(l.uncommittedPreimages, pre)
// Pipeline this settle, send it to the switch.
go l.forwardBatch(settlePacket)
case *lnwire.UpdateFailMalformedHTLC:
// Convert the failure type encoded within the HTLC fail
// message to the proper generic lnwire error code.
var failure lnwire.FailureMessage
switch msg.FailureCode {
case lnwire.CodeInvalidOnionVersion:
failure = &lnwire.FailInvalidOnionVersion{
OnionSHA256: msg.ShaOnionBlob,
}
case lnwire.CodeInvalidOnionHmac:
failure = &lnwire.FailInvalidOnionHmac{
OnionSHA256: msg.ShaOnionBlob,
}
case lnwire.CodeInvalidOnionKey:
failure = &lnwire.FailInvalidOnionKey{
OnionSHA256: msg.ShaOnionBlob,
}
default:
log.Warnf("Unexpected failure code received in "+
"UpdateFailMailformedHTLC: %v", msg.FailureCode)
// We don't just pass back the error we received from
// our successor. Otherwise we might report a failure
// that penalizes us more than needed. If the onion that
// we forwarded was correct, the node should have been
// able to send back its own failure. The node did not
// send back its own failure, so we assume there was a
// problem with the onion and report that back. We reuse
// the invalid onion key failure because there is no
// specific error for this case.
failure = &lnwire.FailInvalidOnionKey{
OnionSHA256: msg.ShaOnionBlob,
}
}
// With the error parsed, we'll convert the into it's opaque
// form.
var b bytes.Buffer
if err := lnwire.EncodeFailure(&b, failure, 0); err != nil {
l.errorf("unable to encode malformed error: %v", err)
return
}
// If remote side have been unable to parse the onion blob we
// have sent to it, than we should transform the malformed HTLC
// message to the usual HTLC fail message.
err := l.channel.ReceiveFailHTLC(msg.ID, b.Bytes())
if err != nil {
l.fail(LinkFailureError{code: ErrInvalidUpdate},
"unable to handle upstream fail HTLC: %v", err)
return
}
case *lnwire.UpdateFailHTLC:
idx := msg.ID
err := l.channel.ReceiveFailHTLC(idx, msg.Reason[:])
if err != nil {
l.fail(LinkFailureError{code: ErrInvalidUpdate},
"unable to handle upstream fail HTLC: %v", err)
return
}
case *lnwire.CommitSig:
// Since we may have learned new preimages for the first time,
// we'll add them to our preimage cache. By doing this, we
// ensure any contested contracts watched by any on-chain
// arbitrators can now sweep this HTLC on-chain. We delay
// committing the preimages until just before accepting the new
// remote commitment, as afterwards the peer won't resend the
// Settle messages on the next channel reestablishment. Doing so
// allows us to more effectively batch this operation, instead
// of doing a single write per preimage.
err := l.cfg.PreimageCache.AddPreimages(
l.uncommittedPreimages...,
)
if err != nil {
l.fail(
LinkFailureError{code: ErrInternalError},
"unable to add preimages=%v to cache: %v",
l.uncommittedPreimages, err,
)
return
}
// Instead of truncating the slice to conserve memory
// allocations, we simply set the uncommitted preimage slice to
// nil so that a new one will be initialized if any more
// witnesses are discovered. We do this maximum size of the
// slice can occupy 15KB, and want to ensure we release that
// memory back to the runtime.
l.uncommittedPreimages = nil
// We just received a new updates to our local commitment
// chain, validate this new commitment, closing the link if
// invalid.
err = l.channel.ReceiveNewCommitment(msg.CommitSig, msg.HtlcSigs)
if err != nil {
// If we were unable to reconstruct their proposed
// commitment, then we'll examine the type of error. If
// it's an InvalidCommitSigError, then we'll send a
// direct error.
var sendData []byte
switch err.(type) {
case *lnwallet.InvalidCommitSigError:
sendData = []byte(err.Error())
case *lnwallet.InvalidHtlcSigError:
sendData = []byte(err.Error())
}
l.fail(
LinkFailureError{
code: ErrInvalidCommitment,
ForceClose: true,
SendData: sendData,
},
"ChannelPoint(%v): unable to accept new "+
"commitment: %v",
l.channel.ChannelPoint(), err,
)
return
}
// As we've just accepted a new state, we'll now
// immediately send the remote peer a revocation for our prior
// state.
nextRevocation, currentHtlcs, err := l.channel.RevokeCurrentCommitment()
if err != nil {
log.Errorf("unable to revoke commitment: %v", err)
return
}
l.cfg.Peer.SendMessage(false, nextRevocation)
// Since we just revoked our commitment, we may have a new set
// of HTLC's on our commitment, so we'll send them over our
// HTLC update channel so any callers can be notified.
select {
case l.htlcUpdates <- &contractcourt.ContractUpdate{
HtlcKey: contractcourt.LocalHtlcSet,
Htlcs: currentHtlcs,
}:
case <-l.quit:
return
}
// As we've just received a commitment signature, we'll
// re-start the log commit timer to wake up the main processing
// loop to check if we need to send a commitment signature as
// we owe one.
//
// TODO(roasbeef): instead after revocation?
if !l.logCommitTimer.Stop() {
select {
case <-l.logCommitTimer.C:
default:
}
}
l.logCommitTimer.Reset(300 * time.Millisecond)
l.logCommitTick = l.logCommitTimer.C
// If both commitment chains are fully synced from our PoV,
// then we don't need to reply with a signature as both sides
// already have a commitment with the latest accepted.
if l.channel.FullySynced() {
return
}
// Otherwise, the remote party initiated the state transition,
// so we'll reply with a signature to provide them with their
// version of the latest commitment.
if err := l.updateCommitTx(); err != nil {
l.fail(LinkFailureError{code: ErrInternalError},
"unable to update commitment: %v", err)
return
}
case *lnwire.RevokeAndAck:
// We've received a revocation from the remote chain, if valid,
// this moves the remote chain forward, and expands our
// revocation window.
fwdPkg, adds, settleFails, remoteHTLCs, err := l.channel.ReceiveRevocation(
msg,
)
if err != nil {
// TODO(halseth): force close?
l.fail(LinkFailureError{code: ErrInvalidRevocation},
"unable to accept revocation: %v", err)
return
}
// The remote party now has a new primary commitment, so we'll
// update the contract court to be aware of this new set (the
// prior old remote pending).
select {
case l.htlcUpdates <- &contractcourt.ContractUpdate{
HtlcKey: contractcourt.RemoteHtlcSet,
Htlcs: remoteHTLCs,
}:
case <-l.quit:
return
}
// If we have a tower client, we'll proceed in backing up the
// state that was just revoked.
if l.cfg.TowerClient != nil {
state := l.channel.State()
breachInfo, err := lnwallet.NewBreachRetribution(
state, state.RemoteCommitment.CommitHeight-1, 0,
)
if err != nil {
l.fail(LinkFailureError{code: ErrInternalError},
"failed to load breach info: %v", err)
return
}
chanID := l.ChanID()
err = l.cfg.TowerClient.BackupState(&chanID, breachInfo)
if err != nil {
l.fail(LinkFailureError{code: ErrInternalError},
"unable to queue breach backup: %v", err)
return
}
}
l.processRemoteSettleFails(fwdPkg, settleFails)
needUpdate := l.processRemoteAdds(fwdPkg, adds)
// If the link failed during processing the adds, we must
// return to ensure we won't attempted to update the state
// further.
if l.failed {
return
}
if needUpdate {
if err := l.updateCommitTx(); err != nil {
l.fail(LinkFailureError{code: ErrInternalError},
"unable to update commitment: %v", err)
return
}
}
case *lnwire.UpdateFee:
// We received fee update from peer. If we are the initiator we
// will fail the channel, if not we will apply the update.
fee := lnwallet.SatPerKWeight(msg.FeePerKw)
if err := l.channel.ReceiveUpdateFee(fee); err != nil {
l.fail(LinkFailureError{code: ErrInvalidUpdate},
"error receiving fee update: %v", err)
return
}
case *lnwire.Error:
// Error received from remote, MUST fail channel, but should
// only print the contents of the error message if all
// characters are printable ASCII.
errMsg := "non-ascii data"
if isASCII(msg.Data) {
errMsg = string(msg.Data)
}
l.fail(LinkFailureError{code: ErrRemoteError},
"ChannelPoint(%v): received error from peer: %v",
l.channel.ChannelPoint(), errMsg)
default:
log.Warnf("ChannelPoint(%v): received unknown message of type %T",
l.channel.ChannelPoint(), msg)
}
}
// ackDownStreamPackets is responsible for removing htlcs from a link's mailbox
// for packets delivered from server, and cleaning up any circuits closed by
// signing a previous commitment txn. This method ensures that the circuits are
// removed from the circuit map before removing them from the link's mailbox,
// otherwise it could be possible for some circuit to be missed if this link
// flaps.
func (l *channelLink) ackDownStreamPackets() error {
// First, remove the downstream Add packets that were included in the
// previous commitment signature. This will prevent the Adds from being
// replayed if this link disconnects.
for _, inKey := range l.openedCircuits {
// In order to test the sphinx replay logic of the remote
// party, unsafe replay does not acknowledge the packets from
// the mailbox. We can then force a replay of any Add packets
// held in memory by disconnecting and reconnecting the link.
if l.cfg.UnsafeReplay {
continue
}
l.debugf("removing Add packet %s from mailbox", inKey)
l.mailBox.AckPacket(inKey)
}
// Now, we will delete all circuits closed by the previous commitment
// signature, which is the result of downstream Settle/Fail packets. We
// batch them here to ensure circuits are closed atomically and for
// performance.
err := l.cfg.Circuits.DeleteCircuits(l.closedCircuits...)
switch err {
case nil:
// Successful deletion.
default:
l.errorf("unable to delete %d circuits: %v",
len(l.closedCircuits), err)
return err
}
// With the circuits removed from memory and disk, we now ack any
// Settle/Fails in the mailbox to ensure they do not get redelivered
// after startup. If forgive is enabled and we've reached this point,
// the circuits must have been removed at some point, so it is now safe
// to un-queue the corresponding Settle/Fails.
for _, inKey := range l.closedCircuits {
l.debugf("removing Fail/Settle packet %s from mailbox", inKey)
l.mailBox.AckPacket(inKey)
}
// Lastly, reset our buffers to be empty while keeping any acquired
// growth in the backing array.
l.openedCircuits = l.openedCircuits[:0]
l.closedCircuits = l.closedCircuits[:0]
return nil
}
// 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 (l *channelLink) updateCommitTx() error {
// Preemptively write all pending keystones to disk, just in case the
// HTLCs we have in memory are included in the subsequent attempt to
// sign a commitment state.
err := l.cfg.Circuits.OpenCircuits(l.keystoneBatch...)
if err != nil {
return err
}
// Reset the batch, but keep the backing buffer to avoid reallocating.
l.keystoneBatch = l.keystoneBatch[:0]
// If hodl.Commit mode is active, we will refrain from attempting to
// commit any in-memory modifications to the channel state. Exiting here
// permits testing of either the switch or link's ability to trim
// circuits that have been opened, but unsuccessfully committed.
if l.cfg.HodlMask.Active(hodl.Commit) {
l.warnf(hodl.Commit.Warning())
return nil
}
theirCommitSig, htlcSigs, pendingHTLCs, err := l.channel.SignNextCommitment()
if err == lnwallet.ErrNoWindow {
l.tracef("revocation window exhausted, unable to send: %v, "+
"dangling_opens=%v, dangling_closes%v",
l.batchCounter, newLogClosure(func() string {
return spew.Sdump(l.openedCircuits)
}),
newLogClosure(func() string {
return spew.Sdump(l.closedCircuits)
}),
)
return nil
} else if err != nil {
return err
}
// The remote party now has a new pending commitment, so we'll update
// the contract court to be aware of this new set (the prior old remote
// pending).
select {
case l.htlcUpdates <- &contractcourt.ContractUpdate{
HtlcKey: contractcourt.RemotePendingHtlcSet,
Htlcs: pendingHTLCs,
}:
case <-l.quit:
return nil
}
if err := l.ackDownStreamPackets(); err != nil {
return err
}
commitSig := &lnwire.CommitSig{
ChanID: l.ChanID(),
CommitSig: theirCommitSig,
HtlcSigs: htlcSigs,
}
l.cfg.Peer.SendMessage(false, commitSig)
// We've just initiated a state transition, attempt to stop the
// logCommitTimer. If the timer already ticked, then we'll consume the
// value, dropping
if l.logCommitTimer != nil && !l.logCommitTimer.Stop() {
select {
case <-l.logCommitTimer.C:
default:
}
}
l.logCommitTick = nil
// Finally, clear our the current batch, so we can accurately make
// further batch flushing decisions.
l.batchCounter = 0
return nil
}
// Peer returns the representation of remote peer with which we have the
// channel link opened.
//
// NOTE: Part of the ChannelLink interface.
func (l *channelLink) Peer() lnpeer.Peer {
return l.cfg.Peer
}
// ChannelPoint returns the channel outpoint for the channel link.
// NOTE: Part of the ChannelLink interface.
func (l *channelLink) ChannelPoint() *wire.OutPoint {
return l.channel.ChannelPoint()
}
// ShortChanID returns the short channel ID for the channel link. The short
// channel ID encodes the exact location in the main chain that the original
// funding output can be found.
//
// NOTE: Part of the ChannelLink interface.
func (l *channelLink) ShortChanID() lnwire.ShortChannelID {
l.RLock()
defer l.RUnlock()
return l.shortChanID
}
// UpdateShortChanID updates the short channel ID for a link. This may be
// required in the event that a link is created before the short chan ID for it
// is known, or a re-org occurs, and the funding transaction changes location
// within the chain.
//
// NOTE: Part of the ChannelLink interface.
func (l *channelLink) UpdateShortChanID() (lnwire.ShortChannelID, error) {
chanID := l.ChanID()
// Refresh the channel state's short channel ID by loading it from disk.
// This ensures that the channel state accurately reflects the updated
// short channel ID.
err := l.channel.State().RefreshShortChanID()
if err != nil {
l.errorf("unable to refresh short_chan_id for chan_id=%v: %v",
chanID, err)
return sourceHop, err
}
sid := l.channel.ShortChanID()
l.infof("Updating to short_chan_id=%v for chan_id=%v", sid, chanID)
l.Lock()
l.shortChanID = sid
l.Unlock()
go func() {
err := l.cfg.UpdateContractSignals(&contractcourt.ContractSignals{
HtlcUpdates: l.htlcUpdates,
ShortChanID: sid,
})
if err != nil {
log.Errorf("Unable to update signals for "+
"ChannelLink(%v)", l)
}
}()
// Now that the short channel ID has been properly updated, we can begin
// garbage collecting any forwarding packages we create.
l.wg.Add(1)
go l.fwdPkgGarbager()
return sid, nil
}
// ChanID returns the channel ID for the channel link. The channel ID is a more
// compact representation of a channel's full outpoint.
//
// NOTE: Part of the ChannelLink interface.
func (l *channelLink) ChanID() lnwire.ChannelID {
return lnwire.NewChanIDFromOutPoint(l.channel.ChannelPoint())
}
// Bandwidth returns the total amount that can flow through the channel link at
// this given instance. The value returned is expressed in millisatoshi and can
// be used by callers when making forwarding decisions to determine if a link
// can accept an HTLC.
//
// NOTE: Part of the ChannelLink interface.
func (l *channelLink) Bandwidth() lnwire.MilliSatoshi {
channelBandwidth := l.channel.AvailableBalance()
overflowBandwidth := l.overflowQueue.TotalHtlcAmount()
// To compute the total bandwidth, we'll take the current available
// bandwidth, then subtract the overflow bandwidth as we'll eventually
// also need to evaluate those HTLC's once space on the commitment
// transaction is free.
linkBandwidth := channelBandwidth - overflowBandwidth
// If the channel reserve is greater than the total available balance
// of the link, just return 0.
reserve := lnwire.NewMSatFromSatoshis(l.channel.LocalChanReserve())
if linkBandwidth < reserve {
return 0
}
// Else the amount that is available to flow through the link at this
// point is the available balance minus the reserve amount we are
// required to keep as collateral.
return linkBandwidth - reserve
}
// AttachMailBox updates the current mailbox used by this link, and hooks up
// the mailbox's message and packet outboxes to the link's upstream and
// downstream chans, respectively.
func (l *channelLink) AttachMailBox(mailbox MailBox) {
l.Lock()
l.mailBox = mailbox
l.upstream = mailbox.MessageOutBox()
l.downstream = mailbox.PacketOutBox()
l.Unlock()
}
// UpdateForwardingPolicy updates the forwarding policy for the target
// ChannelLink. Once updated, the link will use the new forwarding policy to
// govern if it an incoming HTLC should be forwarded or not. Note that this
// processing of the new policy will ensure that uninitialized fields in the
// passed policy won't override already initialized fields in the current
// policy.
//
// NOTE: Part of the ChannelLink interface.
func (l *channelLink) UpdateForwardingPolicy(newPolicy ForwardingPolicy) {
l.Lock()
defer l.Unlock()
// In order to avoid overriding a valid policy with a "null" field in
// the new policy, we'll only update to the set sub policy if the new
// value isn't uninitialized.
if newPolicy.BaseFee != 0 {
l.cfg.FwrdingPolicy.BaseFee = newPolicy.BaseFee
}
if newPolicy.FeeRate != 0 {
l.cfg.FwrdingPolicy.FeeRate = newPolicy.FeeRate
}
if newPolicy.TimeLockDelta != 0 {
l.cfg.FwrdingPolicy.TimeLockDelta = newPolicy.TimeLockDelta
}
if newPolicy.MinHTLC != 0 {
l.cfg.FwrdingPolicy.MinHTLC = newPolicy.MinHTLC
}
}
// HtlcSatifiesPolicy should return a nil error if the passed HTLC details
// satisfy the current forwarding policy fo the target link. Otherwise, a
// valid protocol failure message should be returned in order to signal to the
// source of the HTLC, the policy consistency issue.
//
// NOTE: Part of the ChannelLink interface.
func (l *channelLink) HtlcSatifiesPolicy(payHash [32]byte,
incomingHtlcAmt, amtToForward lnwire.MilliSatoshi,
incomingTimeout, outgoingTimeout uint32,
heightNow uint32) lnwire.FailureMessage {
l.RLock()
policy := l.cfg.FwrdingPolicy
l.RUnlock()
// First check whether the outgoing htlc satisfies the channel policy.
err := l.htlcSatifiesPolicyOutgoing(
policy, payHash, amtToForward, outgoingTimeout, heightNow,
)
if err != nil {
return err
}
// Next, using the amount of the incoming HTLC, we'll calculate the
// expected fee this incoming HTLC must carry in order to satisfy the
// constraints of the outgoing link.
expectedFee := ExpectedFee(policy, amtToForward)
// If the actual fee is less than our expected fee, then we'll reject
// this HTLC as it didn't provide a sufficient amount of fees, or the
// values have been tampered with, or the send used incorrect/dated
// information to construct the forwarding information for this hop. In
// any case, we'll cancel this HTLC.
actualFee := incomingHtlcAmt - amtToForward
if incomingHtlcAmt < amtToForward || actualFee < expectedFee {
l.errorf("outgoing htlc(%x) has insufficient fee: expected %v, "+
"got %v", payHash[:], int64(expectedFee), int64(actualFee))
// As part of the returned error, we'll send our latest routing
// policy so the sending node obtains the most up to date data.
var failure lnwire.FailureMessage
update, err := l.cfg.FetchLastChannelUpdate(l.ShortChanID())
if err != nil {
failure = &lnwire.FailTemporaryNodeFailure{}
} else {
failure = lnwire.NewFeeInsufficient(
amtToForward, *update,
)
}
return failure
}
// Finally, we'll ensure that the time-lock on the outgoing HTLC meets
// the following constraint: the incoming time-lock minus our time-lock
// delta should equal the outgoing time lock. Otherwise, whether the
// sender messed up, or an intermediate node tampered with the HTLC.
timeDelta := policy.TimeLockDelta
if incomingTimeout < outgoingTimeout+timeDelta {
l.errorf("Incoming htlc(%x) has incorrect time-lock value: "+
"expected at least %v block delta, got %v block delta",
payHash[:], timeDelta, incomingTimeout-outgoingTimeout)
// Grab the latest routing policy so the sending node is up to
// date with our current policy.
var failure lnwire.FailureMessage
update, err := l.cfg.FetchLastChannelUpdate(
l.ShortChanID(),
)
if err != nil {
failure = lnwire.NewTemporaryChannelFailure(update)
} else {
failure = lnwire.NewIncorrectCltvExpiry(
incomingTimeout, *update,
)
}
return failure
}
return nil
}
// HtlcSatifiesPolicyLocal should return a nil error if the passed HTLC details
// satisfy the current channel policy. Otherwise, a valid protocol failure
// message should be returned in order to signal the violation. This call is
// intended to be used for locally initiated payments for which there is no
// corresponding incoming htlc.
func (l *channelLink) HtlcSatifiesPolicyLocal(payHash [32]byte,
amt lnwire.MilliSatoshi, timeout uint32,
heightNow uint32) lnwire.FailureMessage {
l.RLock()
policy := l.cfg.FwrdingPolicy
l.RUnlock()
return l.htlcSatifiesPolicyOutgoing(
policy, payHash, amt, timeout, heightNow,
)
}
// htlcSatifiesPolicyOutgoing checks whether the given htlc parameters satisfy
// the channel's amount and time lock constraints.
func (l *channelLink) htlcSatifiesPolicyOutgoing(policy ForwardingPolicy,
payHash [32]byte, amt lnwire.MilliSatoshi, timeout uint32,
heightNow uint32) lnwire.FailureMessage {
// As our first sanity check, we'll ensure that the passed HTLC isn't
// too small for the next hop. If so, then we'll cancel the HTLC
// directly.
if amt < policy.MinHTLC {
l.errorf("outgoing htlc(%x) is too small: min_htlc=%v, "+
"htlc_value=%v", payHash[:], policy.MinHTLC,
amt)
// As part of the returned error, we'll send our latest routing
// policy so the sending node obtains the most up to date data.
var failure lnwire.FailureMessage
update, err := l.cfg.FetchLastChannelUpdate(l.ShortChanID())
if err != nil {
failure = &lnwire.FailTemporaryNodeFailure{}
} else {
failure = lnwire.NewAmountBelowMinimum(
amt, *update,
)
}
return failure
}
// Next, ensure that the passed HTLC isn't too large. If so, we'll cancel
// the HTLC directly.
if policy.MaxHTLC != 0 && amt > policy.MaxHTLC {
l.errorf("outgoing htlc(%x) is too large: max_htlc=%v, "+
"htlc_value=%v", payHash[:], policy.MaxHTLC, amt)
// As part of the returned error, we'll send our latest routing policy
// so the sending node obtains the most up-to-date data.
var failure lnwire.FailureMessage
update, err := l.cfg.FetchLastChannelUpdate(l.ShortChanID())
if err != nil {
failure = &lnwire.FailTemporaryNodeFailure{}
} else {
failure = lnwire.NewTemporaryChannelFailure(update)
}
return failure
}
// We want to avoid offering an HTLC which will expire in the near
// future, so we'll reject an HTLC if the outgoing expiration time is
// too close to the current height.
if timeout <= heightNow+l.cfg.OutgoingCltvRejectDelta {
l.errorf("htlc(%x) has an expiry that's too soon: "+
"outgoing_expiry=%v, best_height=%v", payHash[:],
timeout, heightNow)
var failure lnwire.FailureMessage
update, err := l.cfg.FetchLastChannelUpdate(
l.ShortChanID(),
)
if err != nil {
failure = lnwire.NewTemporaryChannelFailure(update)
} else {
failure = lnwire.NewExpiryTooSoon(*update)
}
return failure
}
// Check absolute max delta.
if timeout > l.cfg.MaxOutgoingCltvExpiry+heightNow {
l.errorf("outgoing htlc(%x) has a time lock too far in the "+
"future: got %v, but maximum is %v", payHash[:],
timeout-heightNow, l.cfg.MaxOutgoingCltvExpiry)
return &lnwire.FailExpiryTooFar{}
}
return nil
}
// Stats returns the statistics of channel link.
//
// NOTE: Part of the ChannelLink interface.
func (l *channelLink) Stats() (uint64, lnwire.MilliSatoshi, lnwire.MilliSatoshi) {
snapshot := l.channel.StateSnapshot()
return snapshot.ChannelCommitment.CommitHeight,
snapshot.TotalMSatSent,
snapshot.TotalMSatReceived
}
// String returns the string representation of channel link.
//
// NOTE: Part of the ChannelLink interface.
func (l *channelLink) String() string {
return l.channel.ChannelPoint().String()
}
// HandleSwitchPacket handles the switch packets. This packets which might be
// forwarded to us from another channel link in case the htlc update came from
// another peer or if the update was created by user
//
// NOTE: Part of the ChannelLink interface.
func (l *channelLink) HandleSwitchPacket(pkt *htlcPacket) error {
l.tracef("received switch packet inkey=%v, outkey=%v",
pkt.inKey(), pkt.outKey())
l.mailBox.AddPacket(pkt)
return nil
}
// HandleChannelUpdate handles the htlc requests as settle/add/fail which sent
// to us from remote peer we have a channel with.
//
// NOTE: Part of the ChannelLink interface.
func (l *channelLink) HandleChannelUpdate(message lnwire.Message) {
l.mailBox.AddMessage(message)
}
// updateChannelFee updates the commitment fee-per-kw on this channel by
// committing to an update_fee message.
func (l *channelLink) updateChannelFee(feePerKw lnwallet.SatPerKWeight) error {
log.Infof("ChannelPoint(%v): updating commit fee to %v sat/kw", l,
feePerKw)
// We skip sending the UpdateFee message if the channel is not
// currently eligible to forward messages.
if !l.EligibleToForward() {
log.Debugf("ChannelPoint(%v): skipping fee update for "+
"inactive channel", l.ChanID())
return nil
}
// First, we'll update the local fee on our commitment.
if err := l.channel.UpdateFee(feePerKw); err != nil {
return err
}
// We'll then attempt to send a new UpdateFee message, and also lock it
// in immediately by triggering a commitment update.
msg := lnwire.NewUpdateFee(l.ChanID(), uint32(feePerKw))
if err := l.cfg.Peer.SendMessage(false, msg); err != nil {
return err
}
return l.updateCommitTx()
}
// processRemoteSettleFails accepts a batch of settle/fail payment descriptors
// after receiving a revocation from the remote party, and reprocesses them in
// the context of the provided forwarding package. Any settles or fails that
// have already been acknowledged in the forwarding package will not be sent to
// the switch.
func (l *channelLink) processRemoteSettleFails(fwdPkg *channeldb.FwdPkg,
settleFails []*lnwallet.PaymentDescriptor) {
if len(settleFails) == 0 {
return
}
log.Debugf("ChannelLink(%v): settle-fail-filter %v",
l.ShortChanID(), fwdPkg.SettleFailFilter)
var switchPackets []*htlcPacket
for i, pd := range settleFails {
// Skip any settles or fails that have already been
// acknowledged by the incoming link that originated the
// forwarded Add.
if fwdPkg.SettleFailFilter.Contains(uint16(i)) {
continue
}
// TODO(roasbeef): rework log entries to a shared
// interface.
switch pd.EntryType {
// A settle for an HTLC we previously forwarded HTLC has been
// received. So we'll forward the HTLC to the switch which will
// handle propagating the settle to the prior hop.
case lnwallet.Settle:
// If hodl.SettleIncoming is requested, we will not
// forward the SETTLE to the switch and will not signal
// a free slot on the commitment transaction.
if l.cfg.HodlMask.Active(hodl.SettleIncoming) {
l.warnf(hodl.SettleIncoming.Warning())
continue
}
settlePacket := &htlcPacket{
outgoingChanID: l.ShortChanID(),
outgoingHTLCID: pd.ParentIndex,
destRef: pd.DestRef,
htlc: &lnwire.UpdateFulfillHTLC{
PaymentPreimage: pd.RPreimage,
},
}
// Add the packet to the batch to be forwarded, and
// notify the overflow queue that a spare spot has been
// freed up within the commitment state.
switchPackets = append(switchPackets, settlePacket)
l.overflowQueue.SignalFreeSlot()
// A failureCode message for a previously forwarded HTLC has
// been received. As a result a new slot will be freed up in
// our commitment state, so we'll forward this to the switch so
// the backwards undo can continue.
case lnwallet.Fail:
// If hodl.SettleIncoming is requested, we will not
// forward the FAIL to the switch and will not signal a
// free slot on the commitment transaction.
if l.cfg.HodlMask.Active(hodl.FailIncoming) {
l.warnf(hodl.FailIncoming.Warning())
continue
}
// Fetch the reason the HTLC was cancelled so we can
// continue to propagate it.
failPacket := &htlcPacket{
outgoingChanID: l.ShortChanID(),
outgoingHTLCID: pd.ParentIndex,
destRef: pd.DestRef,
htlc: &lnwire.UpdateFailHTLC{
Reason: lnwire.OpaqueReason(
pd.FailReason,
),
},
}
// If the failure message lacks an HMAC (but includes
// the 4 bytes for encoding the message and padding
// lengths, then this means that we received it as an
// UpdateFailMalformedHTLC. As a result, we'll signal
// that we need to convert this error within the switch
// to an actual error, by encrypting it as if we were
// the originating hop.
convertedErrorSize := lnwire.FailureMessageLength + 4
if len(pd.FailReason) == convertedErrorSize {
failPacket.convertedError = true
}
// Add the packet to the batch to be forwarded, and
// notify the overflow queue that a spare spot has been
// freed up within the commitment state.
switchPackets = append(switchPackets, failPacket)
l.overflowQueue.SignalFreeSlot()
}
}
// Only spawn the task forward packets we have a non-zero number.
if len(switchPackets) > 0 {
go l.forwardBatch(switchPackets...)
}
}
// processRemoteAdds serially processes each of the Add payment descriptors
// which have been "locked-in" by receiving a revocation from the remote party.
// The forwarding package provided instructs how to process this batch,
// indicating whether this is the first time these Adds are being processed, or
// whether we are reprocessing as a result of a failure or restart. Adds that
// have already been acknowledged in the forwarding package will be ignored.
func (l *channelLink) processRemoteAdds(fwdPkg *channeldb.FwdPkg,
lockedInHtlcs []*lnwallet.PaymentDescriptor) bool {
l.tracef("processing %d remote adds for height %d",
len(lockedInHtlcs), fwdPkg.Height)
decodeReqs := make([]DecodeHopIteratorRequest, 0, len(lockedInHtlcs))
for _, pd := range lockedInHtlcs {
switch pd.EntryType {
// TODO(conner): remove type switch?
case lnwallet.Add:
// Before adding the new htlc to the state machine,
// parse the onion object in order to obtain the
// routing information with DecodeHopIterator function
// which process the Sphinx packet.
onionReader := bytes.NewReader(pd.OnionBlob)
req := DecodeHopIteratorRequest{
OnionReader: onionReader,
RHash: pd.RHash[:],
IncomingCltv: pd.Timeout,
}
decodeReqs = append(decodeReqs, req)
}
}
// Atomically decode the incoming htlcs, simultaneously checking for
// replay attempts. A particular index in the returned, spare list of
// channel iterators should only be used if the failure code at the
// same index is lnwire.FailCodeNone.
decodeResps, sphinxErr := l.cfg.DecodeHopIterators(
fwdPkg.ID(), decodeReqs,
)
if sphinxErr != nil {
l.fail(LinkFailureError{code: ErrInternalError},
"unable to decode hop iterators: %v", sphinxErr)
return false
}
var (
needUpdate bool
switchPackets []*htlcPacket
)
for i, pd := range lockedInHtlcs {
idx := uint16(i)
if fwdPkg.State == channeldb.FwdStateProcessed &&
fwdPkg.AckFilter.Contains(idx) {
// If this index is already found in the ack filter,
// the response to this forwarding decision has already
// been committed by one of our commitment txns. ADDs
// in this state are waiting for the rest of the fwding
// package to get acked before being garbage collected.
continue
}
// An incoming HTLC add has been full-locked in. As a result we
// can now examine the forwarding details of the HTLC, and the
// HTLC itself to decide if: we should forward it, cancel it,
// or are able to settle it (and it adheres to our fee related
// constraints).
// Fetch the onion blob that was included within this processed
// payment descriptor.
var onionBlob [lnwire.OnionPacketSize]byte
copy(onionBlob[:], pd.OnionBlob)
// Before adding the new htlc to the state machine, parse the
// onion object in order to obtain the routing information with
// DecodeHopIterator function which process the Sphinx packet.
chanIterator, failureCode := decodeResps[i].Result()
if failureCode != lnwire.CodeNone {
// If we're unable to process the onion blob than we
// should send the malformed htlc error to payment
// sender.
l.sendMalformedHTLCError(pd.HtlcIndex, failureCode,
onionBlob[:], pd.SourceRef)
needUpdate = true
log.Errorf("unable to decode onion hop "+
"iterator: %v", failureCode)
continue
}
// Retrieve onion obfuscator from onion blob in order to
// produce initial obfuscation of the onion failureCode.
obfuscator, failureCode := chanIterator.ExtractErrorEncrypter(
l.cfg.ExtractErrorEncrypter,
)
if failureCode != lnwire.CodeNone {
// If we're unable to process the onion blob than we
// should send the malformed htlc error to payment
// sender.
l.sendMalformedHTLCError(
pd.HtlcIndex, failureCode, onionBlob[:], pd.SourceRef,
)
needUpdate = true
log.Errorf("unable to decode onion "+
"obfuscator: %v", failureCode)
continue
}
heightNow := l.cfg.Switch.BestHeight()
fwdInfo, err := chanIterator.ForwardingInstructions()
if err != nil {
// If we're unable to process the onion payload, or we
// we received malformed TLV stream, then we should
// send an error back to the caller so the HTLC can be
// cancelled.
l.sendHTLCError(
pd.HtlcIndex,
lnwire.NewInvalidOnionVersion(onionBlob[:]),
obfuscator, pd.SourceRef,
)
needUpdate = true
log.Errorf("Unable to decode forwarding "+
"instructions: %v", err)
continue
}
switch fwdInfo.NextHop {
case exitHop:
updated, err := l.processExitHop(
pd, obfuscator, fwdInfo, heightNow,
chanIterator.ExtraOnionBlob(),
)
if err != nil {
l.fail(LinkFailureError{code: ErrInternalError},
err.Error(),
)
return false
}
if updated {
needUpdate = true
}
// There are additional channels left within this route. So
// we'll simply do some forwarding package book-keeping.
default:
// If hodl.AddIncoming is requested, we will not
// validate the forwarded ADD, nor will we send the
// packet to the htlc switch.
if l.cfg.HodlMask.Active(hodl.AddIncoming) {
l.warnf(hodl.AddIncoming.Warning())
continue
}
switch fwdPkg.State {
case channeldb.FwdStateProcessed:
// This add was not forwarded on the previous
// processing phase, run it through our
// validation pipeline to reproduce an error.
// This may trigger a different error due to
// expiring timelocks, but we expect that an
// error will be reproduced.
if !fwdPkg.FwdFilter.Contains(idx) {
break
}
// Otherwise, it was already processed, we can
// can collect it and continue.
addMsg := &lnwire.UpdateAddHTLC{
Expiry: fwdInfo.OutgoingCTLV,
Amount: fwdInfo.AmountToForward,
PaymentHash: pd.RHash,
}
// Finally, we'll encode the onion packet for
// the _next_ hop using the hop iterator
// decoded for the current hop.
buf := bytes.NewBuffer(addMsg.OnionBlob[0:0])
// We know this cannot fail, as this ADD
// was marked forwarded in a previous
// round of processing.
chanIterator.EncodeNextHop(buf)
updatePacket := &htlcPacket{
incomingChanID: l.ShortChanID(),
incomingHTLCID: pd.HtlcIndex,
outgoingChanID: fwdInfo.NextHop,
sourceRef: pd.SourceRef,
incomingAmount: pd.Amount,
amount: addMsg.Amount,
htlc: addMsg,
obfuscator: obfuscator,
incomingTimeout: pd.Timeout,
outgoingTimeout: fwdInfo.OutgoingCTLV,
}
switchPackets = append(
switchPackets, updatePacket,
)
continue
}
// TODO(roasbeef): ensure don't accept outrageous
// timeout for htlc
// With all our forwarding constraints met, we'll
// create the outgoing HTLC using the parameters as
// specified in the forwarding info.
addMsg := &lnwire.UpdateAddHTLC{
Expiry: fwdInfo.OutgoingCTLV,
Amount: fwdInfo.AmountToForward,
PaymentHash: pd.RHash,
}
// Finally, we'll encode the onion packet for the
// _next_ hop using the hop iterator decoded for the
// current hop.
buf := bytes.NewBuffer(addMsg.OnionBlob[0:0])
err := chanIterator.EncodeNextHop(buf)
if err != nil {
log.Errorf("unable to encode the "+
"remaining route %v", err)
var failure lnwire.FailureMessage
update, err := l.cfg.FetchLastChannelUpdate(
l.ShortChanID(),
)
if err != nil {
failure = &lnwire.FailTemporaryNodeFailure{}
} else {
failure = lnwire.NewTemporaryChannelFailure(
update,
)
}
l.sendHTLCError(
pd.HtlcIndex, failure, obfuscator, pd.SourceRef,
)
needUpdate = true
continue
}
// Now that this add has been reprocessed, only append
// it to our list of packets to forward to the switch
// this is the first time processing the add. If the
// fwd pkg has already been processed, then we entered
// the above section to recreate a previous error. If
// the packet had previously been forwarded, it would
// have been added to switchPackets at the top of this
// section.
if fwdPkg.State == channeldb.FwdStateLockedIn {
updatePacket := &htlcPacket{
incomingChanID: l.ShortChanID(),
incomingHTLCID: pd.HtlcIndex,
outgoingChanID: fwdInfo.NextHop,
sourceRef: pd.SourceRef,
incomingAmount: pd.Amount,
amount: addMsg.Amount,
htlc: addMsg,
obfuscator: obfuscator,
incomingTimeout: pd.Timeout,
outgoingTimeout: fwdInfo.OutgoingCTLV,
}
fwdPkg.FwdFilter.Set(idx)
switchPackets = append(switchPackets,
updatePacket)
}
}
}
// Commit the htlcs we are intending to forward if this package has not
// been fully processed.
if fwdPkg.State == channeldb.FwdStateLockedIn {
err := l.channel.SetFwdFilter(fwdPkg.Height, fwdPkg.FwdFilter)
if err != nil {
l.fail(LinkFailureError{code: ErrInternalError},
"unable to set fwd filter: %v", err)
return false
}
}
if len(switchPackets) == 0 {
return needUpdate
}
l.debugf("forwarding %d packets to switch", len(switchPackets))
// NOTE: This call is made synchronous so that we ensure all circuits
// are committed in the exact order that they are processed in the link.
// Failing to do this could cause reorderings/gaps in the range of
// opened circuits, which violates assumptions made by the circuit
// trimming.
l.forwardBatch(switchPackets...)
return needUpdate
}
// processExitHop handles an htlc for which this link is the exit hop. It
// returns a boolean indicating whether the commitment tx needs an update.
func (l *channelLink) processExitHop(pd *lnwallet.PaymentDescriptor,
obfuscator ErrorEncrypter, fwdInfo ForwardingInfo,
heightNow uint32, eob []byte) (bool, error) {
// If hodl.ExitSettle is requested, we will not validate the final hop's
// ADD, nor will we settle the corresponding invoice or respond with the
// preimage.
if l.cfg.HodlMask.Active(hodl.ExitSettle) {
l.warnf(hodl.ExitSettle.Warning())
return false, nil
}
// As we're the exit hop, we'll double check the hop-payload included in
// the HTLC to ensure that it was crafted correctly by the sender and
// matches the HTLC we were extended.
if pd.Amount != fwdInfo.AmountToForward {
log.Errorf("Onion payload of incoming htlc(%x) has incorrect "+
"value: expected %v, got %v", pd.RHash,
pd.Amount, fwdInfo.AmountToForward)
failure := lnwire.NewFinalIncorrectHtlcAmount(pd.Amount)
l.sendHTLCError(pd.HtlcIndex, failure, obfuscator, pd.SourceRef)
return true, nil
}
// We'll also ensure that our time-lock value has been computed
// correctly.
if pd.Timeout != fwdInfo.OutgoingCTLV {
log.Errorf("Onion payload of incoming htlc(%x) has incorrect "+
"time-lock: expected %v, got %v",
pd.RHash[:], pd.Timeout, fwdInfo.OutgoingCTLV)
failure := lnwire.NewFinalIncorrectCltvExpiry(pd.Timeout)
l.sendHTLCError(pd.HtlcIndex, failure, obfuscator, pd.SourceRef)
return true, nil
}
// Notify the invoiceRegistry of the exit hop htlc. If we crash right
// after this, this code will be re-executed after restart. We will
// receive back a resolution event.
invoiceHash := lntypes.Hash(pd.RHash)
event, err := l.cfg.Registry.NotifyExitHopHtlc(
invoiceHash, pd.Amount, pd.Timeout, int32(heightNow),
l.hodlQueue.ChanIn(), eob,
)
switch err {
// Cancel htlc if we don't have an invoice for it.
case channeldb.ErrInvoiceNotFound:
failure := lnwire.NewFailIncorrectDetails(pd.Amount)
l.sendHTLCError(pd.HtlcIndex, failure, obfuscator, pd.SourceRef)
return true, nil
// No error.
case nil:
// Pass error to caller.
default:
return false, err
}
// Create a hodlHtlc struct and decide either resolved now or later.
htlc := hodlHtlc{
pd: pd,
obfuscator: obfuscator,
}
if event == nil {
// Save payment descriptor for future reference.
hodlHtlcs := l.hodlMap[invoiceHash]
l.hodlMap[invoiceHash] = append(hodlHtlcs, htlc)
return false, nil
}
// Process the received resolution.
err = l.processHodlEvent(*event, htlc)
if err != nil {
return false, err
}
return true, nil
}
// settleHTLC settles the HTLC on the channel.
func (l *channelLink) settleHTLC(preimage lntypes.Preimage, htlcIndex uint64,
sourceRef *channeldb.AddRef) error {
hash := preimage.Hash()
l.infof("settling htlc %v as exit hop", hash)
err := l.channel.SettleHTLC(
preimage, htlcIndex, sourceRef, nil, nil,
)
if err != nil {
return fmt.Errorf("unable to settle htlc: %v", err)
}
// If the link is in hodl.BogusSettle mode, replace the preimage with a
// fake one before sending it to the peer.
if l.cfg.HodlMask.Active(hodl.BogusSettle) {
l.warnf(hodl.BogusSettle.Warning())
preimage = [32]byte{}
copy(preimage[:], bytes.Repeat([]byte{2}, 32))
}
// HTLC was successfully settled locally send notification about it
// remote peer.
l.cfg.Peer.SendMessage(false, &lnwire.UpdateFulfillHTLC{
ChanID: l.ChanID(),
ID: htlcIndex,
PaymentPreimage: preimage,
})
return nil
}
// forwardBatch forwards the given htlcPackets to the switch, and waits on the
// err chan for the individual responses. This method is intended to be spawned
// as a goroutine so the responses can be handled in the background.
func (l *channelLink) forwardBatch(packets ...*htlcPacket) {
// Don't forward packets for which we already have a response in our
// mailbox. This could happen if a packet fails and is buffered in the
// mailbox, and the incoming link flaps.
var filteredPkts = make([]*htlcPacket, 0, len(packets))
for _, pkt := range packets {
if l.mailBox.HasPacket(pkt.inKey()) {
continue
}
filteredPkts = append(filteredPkts, pkt)
}
errChan := l.cfg.ForwardPackets(l.quit, filteredPkts...)
go l.handleBatchFwdErrs(errChan)
}
// handleBatchFwdErrs waits on the given errChan until it is closed, logging
// the errors returned from any unsuccessful forwarding attempts.
func (l *channelLink) handleBatchFwdErrs(errChan chan error) {
for {
err, ok := <-errChan
if !ok {
// Err chan has been drained or switch is shutting
// down. Either way, return.
return
}
if err == nil {
continue
}
l.errorf("unhandled error while forwarding htlc packet over "+
"htlcswitch: %v", err)
}
}
// sendHTLCError functions cancels HTLC and send cancel message back to the
// peer from which HTLC was received.
func (l *channelLink) sendHTLCError(htlcIndex uint64, failure lnwire.FailureMessage,
e ErrorEncrypter, sourceRef *channeldb.AddRef) {
reason, err := e.EncryptFirstHop(failure)
if err != nil {
log.Errorf("unable to obfuscate error: %v", err)
return
}
err = l.channel.FailHTLC(htlcIndex, reason, sourceRef, nil, nil)
if err != nil {
log.Errorf("unable cancel htlc: %v", err)
return
}
l.cfg.Peer.SendMessage(false, &lnwire.UpdateFailHTLC{
ChanID: l.ChanID(),
ID: htlcIndex,
Reason: reason,
})
}
// sendMalformedHTLCError helper function which sends the malformed HTLC update
// to the payment sender.
func (l *channelLink) sendMalformedHTLCError(htlcIndex uint64,
code lnwire.FailCode, onionBlob []byte, sourceRef *channeldb.AddRef) {
shaOnionBlob := sha256.Sum256(onionBlob)
err := l.channel.MalformedFailHTLC(htlcIndex, code, shaOnionBlob, sourceRef)
if err != nil {
log.Errorf("unable cancel htlc: %v", err)
return
}
l.cfg.Peer.SendMessage(false, &lnwire.UpdateFailMalformedHTLC{
ChanID: l.ChanID(),
ID: htlcIndex,
ShaOnionBlob: shaOnionBlob,
FailureCode: code,
})
}
// fail is a function which is used to encapsulate the action necessary for
// properly failing the link. It takes a LinkFailureError, which will be passed
// to the OnChannelFailure closure, in order for it to determine if we should
// force close the channel, and if we should send an error message to the
// remote peer.
func (l *channelLink) fail(linkErr LinkFailureError,
format string, a ...interface{}) {
reason := errors.Errorf(format, a...)
// Return if we have already notified about a failure.
if l.failed {
l.warnf("Ignoring link failure (%v), as link already failed",
reason)
return
}
l.errorf("Failing link: %s", reason)
// Set failed, such that we won't process any more updates, and notify
// the peer about the failure.
l.failed = true
l.cfg.OnChannelFailure(l.ChanID(), l.ShortChanID(), linkErr)
}
// infof prefixes the channel's identifier before printing to info log.
func (l *channelLink) infof(format string, a ...interface{}) {
msg := fmt.Sprintf(format, a...)
log.Infof("ChannelLink(%s) %s", l.ShortChanID(), msg)
}
// debugf prefixes the channel's identifier before printing to debug log.
func (l *channelLink) debugf(format string, a ...interface{}) {
msg := fmt.Sprintf(format, a...)
log.Debugf("ChannelLink(%s) %s", l.ShortChanID(), msg)
}
// warnf prefixes the channel's identifier before printing to warn log.
func (l *channelLink) warnf(format string, a ...interface{}) {
msg := fmt.Sprintf(format, a...)
log.Warnf("ChannelLink(%s) %s", l.ShortChanID(), msg)
}
// errorf prefixes the channel's identifier before printing to error log.
func (l *channelLink) errorf(format string, a ...interface{}) {
msg := fmt.Sprintf(format, a...)
log.Errorf("ChannelLink(%s) %s", l.ShortChanID(), msg)
}
// tracef prefixes the channel's identifier before printing to trace log.
func (l *channelLink) tracef(format string, a ...interface{}) {
msg := fmt.Sprintf(format, a...)
log.Tracef("ChannelLink(%s) %s", l.ShortChanID(), msg)
}
// isASCII is a helper method that checks whether all bytes in `data` would be
// printable ASCII characters if interpreted as a string.
func isASCII(data []byte) bool {
isASCII := true
for _, c := range data {
if c < 32 || c > 126 {
isASCII = false
break
}
}
return isASCII
}