lnd.xprv/routing/payment_lifecycle.go

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package routing
import (
"time"
"github.com/davecgh/go-spew/spew"
sphinx "github.com/lightningnetwork/lightning-onion"
"github.com/lightningnetwork/lnd/channeldb"
"github.com/lightningnetwork/lnd/htlcswitch"
"github.com/lightningnetwork/lnd/lntypes"
"github.com/lightningnetwork/lnd/lnwire"
"github.com/lightningnetwork/lnd/routing/route"
)
// paymentLifecycle holds all information about the current state of a payment
// needed to resume if from any point.
type paymentLifecycle struct {
router *ChannelRouter
totalAmount lnwire.MilliSatoshi
feeLimit lnwire.MilliSatoshi
paymentHash lntypes.Hash
paySession PaymentSession
timeoutChan <-chan time.Time
currentHeight int32
}
// resumePayment resumes the paymentLifecycle from the current state.
func (p *paymentLifecycle) resumePayment() ([32]byte, *route.Route, error) {
shardHandler := &shardHandler{
router: p.router,
paymentHash: p.paymentHash,
}
// If we have an existing attempt, we'll start by collecting its result.
payment, err := p.router.cfg.Control.FetchPayment(
p.paymentHash,
)
if err != nil {
return [32]byte{}, nil, err
}
for _, a := range payment.InFlightHTLCs() {
a := a
_, err := shardHandler.collectResult(&a.HTLCAttemptInfo)
if err != nil {
return [32]byte{}, nil, err
}
}
// We'll continue until either our payment succeeds, or we encounter a
// critical error during path finding.
for {
// We start every iteration by fetching the lastest state of
// the payment from the ControlTower. This ensures that we will
// act on the latest available information, whether we are
// resuming an existing payment or just sent a new attempt.
payment, err := p.router.cfg.Control.FetchPayment(
p.paymentHash,
)
if err != nil {
return [32]byte{}, nil, err
}
// Go through the HTLCs for this payment, determining if there
// are any in flight or settled.
var (
attempt *channeldb.HTLCAttemptInfo
settle *channeldb.HTLCAttempt
)
for _, a := range payment.HTLCs {
a := a
// We have a settled HTLC, and should return when all
// shards are back.
if a.Settle != nil {
settle = &a
continue
}
// This HTLC already failed, ignore.
if a.Failure != nil {
continue
}
// HTLC was neither setteld nor failed, it is still in
// flight.
attempt = &a.HTLCAttemptInfo
break
}
// Terminal state, return the preimage and the route taken.
if attempt == nil && settle != nil {
return settle.Settle.Preimage, &settle.Route, nil
}
// If the payment already is failed, and there is no in-flight
// HTLC, return immediately.
if attempt == nil && payment.FailureReason != nil {
return [32]byte{}, nil, *payment.FailureReason
}
// If this payment had no existing payment attempt, we create
// and send one now.
if attempt == nil {
// Before we attempt this next payment, we'll check to see if either
// we've gone past the payment attempt timeout, or the router is
// exiting. In either case, we'll stop this payment attempt short. If a
// timeout is not applicable, timeoutChan will be nil.
select {
case <-p.timeoutChan:
// Mark the payment as failed because of the
// timeout.
err := p.router.cfg.Control.Fail(
p.paymentHash, channeldb.FailureReasonTimeout,
)
if err != nil {
return [32]byte{}, nil, err
}
continue
// The payment will be resumed from the current state
// after restart.
case <-p.router.quit:
return [32]byte{}, nil, ErrRouterShuttingDown
// Fall through if we haven't hit our time limit or are
// exiting.
default:
}
// Create a new payment attempt from the given payment session.
rt, err := p.paySession.RequestRoute(
p.totalAmount, p.feeLimit, 0, uint32(p.currentHeight),
)
if err != nil {
log.Warnf("Failed to find route for payment %x: %v",
p.paymentHash, err)
// Convert error to payment-level failure.
failure := errorToPaymentFailure(err)
// If we're unable to successfully make a payment using
// any of the routes we've found, then mark the payment
// as permanently failed.
saveErr := p.router.cfg.Control.Fail(
p.paymentHash, failure,
)
if saveErr != nil {
return [32]byte{}, nil, saveErr
}
continue
}
// With the route in hand, launch a new shard.
var outcome *launchOutcome
attempt, outcome, err = shardHandler.launchShard(rt)
if err != nil {
return [32]byte{}, nil, err
}
// We ew encountered a non-critical error when
// launching the shard, handle it
if outcome.err != nil {
// We must inspect the error to know whether it
// was critical or not, to decide whether we
// should continue trying.
err = shardHandler.handleSendError(
attempt, outcome.err,
)
if err != nil {
return [32]byte{}, nil, err
}
// Error was handled successfully, continue to
// make a new attempt.
continue
}
// We'll collect the result of the shard just sent. We
// ignore the result for now if it is a success, as we
// will look it up in the control tower on the next
// loop iteration.
result, err := shardHandler.collectResult(attempt)
if err != nil {
return [32]byte{}, nil, err
}
if result.err != nil {
// We must inspect the error to know whether it
// was critical or not, to decide whether we
// should continue trying.
err := shardHandler.handleSendError(
attempt, result.err,
)
if err != nil {
return [32]byte{}, nil, err
}
// Error was handled successfully, continue to
// make a new attempt.
continue
}
}
}
}
// shardHandler holds what is necessary to send and collect the result of
// shards.
type shardHandler struct {
paymentHash lntypes.Hash
router *ChannelRouter
}
// launchOutcome is a type returned from launchShard that indicates whether the
// shard was successfully send onto the network.
type launchOutcome struct {
// err is non-nil if a non-critical error was encountered when trying
// to send the shard, and we successfully updated the control tower to
// reflect this error. This can be errors like not enough local
// balance for the given route etc.
err error
}
// launchShard creates and sends an HTLC attempt along the given route,
// registering it with the control tower before sending it. It returns the
// HTLCAttemptInfo that was created for the shard, along with a launchOutcome.
// The launchOutcome is used to indicate whether the attempt was successfully
// sent. If the launchOutcome wraps a non-nil error, it means that the attempt
// was not sent onto the network, so no result will be available in the future
// for it.
func (p *shardHandler) launchShard(rt *route.Route) (*channeldb.HTLCAttemptInfo,
*launchOutcome, error) {
// Using the route received from the payment session, create a new
// shard to send.
firstHop, htlcAdd, attempt, err := p.createNewPaymentAttempt(
rt,
)
if err != nil {
return nil, nil, err
}
// Before sending this HTLC to the switch, we checkpoint the fresh
// paymentID and route to the DB. This lets us know on startup the ID
// of the payment that we attempted to send, such that we can query the
// Switch for its whereabouts. The route is needed to handle the result
// when it eventually comes back.
err = p.router.cfg.Control.RegisterAttempt(p.paymentHash, attempt)
if err != nil {
return nil, nil, err
}
// Now that the attempt is created and checkpointed to the DB, we send
// it.
sendErr := p.sendPaymentAttempt(attempt, firstHop, htlcAdd)
if sendErr != nil {
// TODO(joostjager): Distinguish unexpected internal errors
// from real send errors.
err := p.failAttempt(attempt, sendErr)
if err != nil {
return nil, nil, err
}
// Return a launchOutcome indicating the shard failed.
return attempt, &launchOutcome{
err: sendErr,
}, nil
}
return attempt, &launchOutcome{}, nil
}
// shardResult holds the resulting outcome of a shard sent.
type shardResult struct {
// preimage is the payment preimage in case of a settled HTLC. Only set
// if err is non-nil.
preimage lntypes.Preimage
// err indicates that the shard failed.
err error
}
// collectResult waits for the result for the given attempt to be available
// from the Switch, then records the attempt outcome with the control tower. A
// shardResult is returned, indicating the final outcome of this HTLC attempt.
func (p *shardHandler) collectResult(attempt *channeldb.HTLCAttemptInfo) (
*shardResult, error) {
// Regenerate the circuit for this attempt.
_, circuit, err := generateSphinxPacket(
&attempt.Route, p.paymentHash[:],
attempt.SessionKey,
)
if err != nil {
return nil, err
}
// Using the created circuit, initialize the error decrypter so we can
// parse+decode any failures incurred by this payment within the
// switch.
errorDecryptor := &htlcswitch.SphinxErrorDecrypter{
OnionErrorDecrypter: sphinx.NewOnionErrorDecrypter(circuit),
}
// Now ask the switch to return the result of the payment when
// available.
resultChan, err := p.router.cfg.Payer.GetPaymentResult(
attempt.AttemptID, p.paymentHash, errorDecryptor,
)
switch {
// If this attempt ID is unknown to the Switch, it means it was never
// checkpointed and forwarded by the switch before a restart. In this
// case we can safely send a new payment attempt, and wait for its
// result to be available.
case err == htlcswitch.ErrPaymentIDNotFound:
log.Debugf("Payment ID %v for hash %x not found in "+
"the Switch, retrying.", attempt.AttemptID,
p.paymentHash)
cErr := p.failAttempt(attempt, err)
if cErr != nil {
return nil, cErr
}
return &shardResult{
err: err,
}, nil
// A critical, unexpected error was encountered.
case err != nil:
log.Errorf("Failed getting result for attemptID %d "+
"from switch: %v", attempt.AttemptID, err)
return nil, err
}
// The switch knows about this payment, we'll wait for a result to be
// available.
var (
result *htlcswitch.PaymentResult
ok bool
)
select {
case result, ok = <-resultChan:
if !ok {
return nil, htlcswitch.ErrSwitchExiting
}
case <-p.router.quit:
return nil, ErrRouterShuttingDown
}
// In case of a payment failure, fail the attempt with the control
// tower and return.
if result.Error != nil {
log.Errorf("Attempt to send payment %x failed: %v",
p.paymentHash, result.Error)
err := p.failAttempt(attempt, result.Error)
if err != nil {
return nil, err
}
return &shardResult{
err: result.Error,
}, nil
}
// We successfully got a payment result back from the switch.
log.Debugf("Payment %x succeeded with pid=%v",
p.paymentHash, attempt.AttemptID)
// Report success to mission control.
err = p.router.cfg.MissionControl.ReportPaymentSuccess(
attempt.AttemptID, &attempt.Route,
)
if err != nil {
log.Errorf("Error reporting payment success to mc: %v",
err)
}
// In case of success we atomically store settle result to the DB move
// the shard to the settled state.
err = p.router.cfg.Control.SettleAttempt(
p.paymentHash, attempt.AttemptID,
&channeldb.HTLCSettleInfo{
Preimage: result.Preimage,
SettleTime: p.router.cfg.Clock.Now(),
},
)
if err != nil {
log.Errorf("Unable to succeed payment attempt: %v", err)
return nil, err
}
return &shardResult{
preimage: result.Preimage,
}, nil
}
// errorToPaymentFailure takes a path finding error and converts it into a
// payment-level failure.
func errorToPaymentFailure(err error) channeldb.FailureReason {
switch err {
case
errNoTlvPayload,
errNoPaymentAddr,
errNoPathFound,
errEmptyPaySession:
return channeldb.FailureReasonNoRoute
2019-11-21 13:59:17 +03:00
case errInsufficientBalance:
return channeldb.FailureReasonInsufficientBalance
}
return channeldb.FailureReasonError
}
// createNewPaymentAttempt creates a new payment attempt from the given route.
func (p *shardHandler) createNewPaymentAttempt(rt *route.Route) (
lnwire.ShortChannelID, *lnwire.UpdateAddHTLC,
*channeldb.HTLCAttemptInfo, error) {
// Generate a new key to be used for this attempt.
sessionKey, err := generateNewSessionKey()
if err != nil {
return lnwire.ShortChannelID{}, nil, nil, err
}
// Generate the raw encoded sphinx packet to be included along
// with the htlcAdd message that we send directly to the
// switch.
onionBlob, _, err := generateSphinxPacket(
rt, p.paymentHash[:], sessionKey,
)
if err != nil {
return lnwire.ShortChannelID{}, nil, nil, err
}
// Craft an HTLC packet to send to the layer 2 switch. The
// metadata within this packet will be used to route the
// payment through the network, starting with the first-hop.
htlcAdd := &lnwire.UpdateAddHTLC{
Amount: rt.TotalAmount,
Expiry: rt.TotalTimeLock,
PaymentHash: p.paymentHash,
}
copy(htlcAdd.OnionBlob[:], onionBlob)
// Attempt to send this payment through the network to complete
// the payment. If this attempt fails, then we'll continue on
// to the next available route.
firstHop := lnwire.NewShortChanIDFromInt(
rt.Hops[0].ChannelID,
)
// We generate a new, unique payment ID that we will use for
// this HTLC.
attemptID, err := p.router.cfg.NextPaymentID()
if err != nil {
return lnwire.ShortChannelID{}, nil, nil, err
}
// We now have all the information needed to populate
// the current attempt information.
attempt := &channeldb.HTLCAttemptInfo{
AttemptID: attemptID,
AttemptTime: p.router.cfg.Clock.Now(),
SessionKey: sessionKey,
Route: *rt,
}
return firstHop, htlcAdd, attempt, nil
}
// sendPaymentAttempt attempts to send the current attempt to the switch.
func (p *shardHandler) sendPaymentAttempt(
attempt *channeldb.HTLCAttemptInfo, firstHop lnwire.ShortChannelID,
htlcAdd *lnwire.UpdateAddHTLC) error {
log.Tracef("Attempting to send payment %x (pid=%v), "+
"using route: %v", p.paymentHash, attempt.AttemptID,
newLogClosure(func() string {
return spew.Sdump(attempt.Route)
}),
)
// Send it to the Switch. When this method returns we assume
// the Switch successfully has persisted the payment attempt,
// such that we can resume waiting for the result after a
// restart.
err := p.router.cfg.Payer.SendHTLC(
firstHop, attempt.AttemptID, htlcAdd,
)
if err != nil {
log.Errorf("Failed sending attempt %d for payment "+
"%x to switch: %v", attempt.AttemptID,
p.paymentHash, err)
return err
}
log.Debugf("Payment %x (pid=%v) successfully sent to switch, route: %v",
p.paymentHash, attempt.AttemptID, &attempt.Route)
return nil
}
// handleSendError inspects the given error from the Switch and determines
// whether we should make another payment attempt, or if it should be
// considered a terminal error. Terminal errors will be recorded with the
// control tower.
func (p *shardHandler) handleSendError(attempt *channeldb.HTLCAttemptInfo,
sendErr error) error {
reason := p.router.processSendError(
attempt.AttemptID, &attempt.Route, sendErr,
)
if reason == nil {
return nil
}
log.Debugf("Payment %x failed: final_outcome=%v, raw_err=%v",
p.paymentHash, *reason, sendErr)
err := p.router.cfg.Control.Fail(p.paymentHash, *reason)
if err != nil {
return err
}
return nil
}
// failAttempt calls control tower to fail the current payment attempt.
func (p *shardHandler) failAttempt(attempt *channeldb.HTLCAttemptInfo,
sendError error) error {
failInfo := marshallError(
sendError,
p.router.cfg.Clock.Now(),
)
return p.router.cfg.Control.FailAttempt(
p.paymentHash, attempt.AttemptID,
failInfo,
)
}
// marshallError marshall an error as received from the switch to a structure
// that is suitable for database storage.
func marshallError(sendError error, time time.Time) *channeldb.HTLCFailInfo {
response := &channeldb.HTLCFailInfo{
FailTime: time,
}
switch sendError {
case htlcswitch.ErrPaymentIDNotFound:
response.Reason = channeldb.HTLCFailInternal
return response
case htlcswitch.ErrUnreadableFailureMessage:
response.Reason = channeldb.HTLCFailUnreadable
return response
}
rtErr, ok := sendError.(htlcswitch.ClearTextError)
if !ok {
response.Reason = channeldb.HTLCFailInternal
return response
}
message := rtErr.WireMessage()
if message != nil {
response.Reason = channeldb.HTLCFailMessage
response.Message = message
} else {
response.Reason = channeldb.HTLCFailUnknown
}
// If the ClearTextError received is a ForwardingError, the error
// originated from a node along the route, not locally on our outgoing
// link. We set failureSourceIdx to the index of the node where the
// failure occurred. If the error is not a ForwardingError, the failure
// occurred at our node, so we leave the index as 0 to indicate that
// we failed locally.
fErr, ok := rtErr.(*htlcswitch.ForwardingError)
if ok {
response.FailureSourceIndex = uint32(fErr.FailureSourceIdx)
}
return response
}