lnd.xprv/routing/payment_lifecycle.go
2019-12-16 14:53:45 +01:00

421 lines
12 KiB
Go

package routing
import (
"fmt"
"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/lnwire"
"github.com/lightningnetwork/lnd/routing/route"
)
// errNoRoute is returned when all routes from the payment session have been
// attempted.
type errNoRoute struct {
// lastError is the error encountered during the last payment attempt,
// if at least one attempt has been made.
lastError error
}
// Error returns a string representation of the error.
func (e errNoRoute) Error() string {
return fmt.Sprintf("unable to route payment to destination: %v",
e.lastError)
}
// paymentLifecycle holds all information about the current state of a payment
// needed to resume if from any point.
type paymentLifecycle struct {
router *ChannelRouter
payment *LightningPayment
paySession PaymentSession
timeoutChan <-chan time.Time
currentHeight int32
finalCLTVDelta uint16
attempt *channeldb.PaymentAttemptInfo
circuit *sphinx.Circuit
lastError error
}
// resumePayment resumes the paymentLifecycle from the current state.
func (p *paymentLifecycle) resumePayment() ([32]byte, *route.Route, error) {
// We'll continue until either our payment succeeds, or we encounter a
// critical error during path finding.
for {
// If this payment had no existing payment attempt, we create
// and send one now.
if p.attempt == nil {
firstHop, htlcAdd, err := p.createNewPaymentAttempt()
if err != nil {
return [32]byte{}, nil, err
}
// Now that the attempt is created and checkpointed to
// the DB, we send it.
sendErr := p.sendPaymentAttempt(firstHop, htlcAdd)
if sendErr != nil {
// We must inspect the error to know whether it
// was critical or not, to decide whether we
// should continue trying.
err := p.handleSendError(sendErr)
if err != nil {
return [32]byte{}, nil, err
}
// Error was handled successfully, reset the
// attempt to indicate we want to make a new
// attempt.
p.attempt = nil
continue
}
} else {
// If this was a resumed attempt, we must regenerate the
// circuit. We don't need to check for errors resulting
// from an invalid route, because the sphinx packet has
// been successfully generated before.
_, c, err := generateSphinxPacket(
&p.attempt.Route, p.payment.PaymentHash[:],
p.attempt.SessionKey,
)
if err != nil {
return [32]byte{}, nil, err
}
p.circuit = c
}
// 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(p.circuit),
}
// Now ask the switch to return the result of the payment when
// available.
resultChan, err := p.router.cfg.Payer.GetPaymentResult(
p.attempt.PaymentID, p.payment.PaymentHash, errorDecryptor,
)
switch {
// If this payment 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.", p.attempt.PaymentID,
p.payment.PaymentHash)
// Reset the attempt to indicate we want to make a new
// attempt.
p.attempt = nil
continue
// A critical, unexpected error was encountered.
case err != nil:
log.Errorf("Failed getting result for paymentID %d "+
"from switch: %v", p.attempt.PaymentID, err)
return [32]byte{}, 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 [32]byte{}, nil, htlcswitch.ErrSwitchExiting
}
case <-p.router.quit:
return [32]byte{}, nil, ErrRouterShuttingDown
}
// In case of a payment failure, we use the error to decide
// whether we should retry.
if result.Error != nil {
log.Errorf("Attempt to send payment %x failed: %v",
p.payment.PaymentHash, result.Error)
// We must inspect the error to know whether it was
// critical or not, to decide whether we should
// continue trying.
if err := p.handleSendError(result.Error); err != nil {
return [32]byte{}, nil, err
}
// Error was handled successfully, reset the attempt to
// indicate we want to make a new attempt.
p.attempt = nil
continue
}
// We successfully got a payment result back from the switch.
log.Debugf("Payment %x succeeded with pid=%v",
p.payment.PaymentHash, p.attempt.PaymentID)
// Report success to mission control.
err = p.router.cfg.MissionControl.ReportPaymentSuccess(
p.attempt.PaymentID, &p.attempt.Route,
)
if err != nil {
log.Errorf("Error reporting payment success to mc: %v",
err)
}
// In case of success we atomically store the db payment and
// move the payment to the success state.
err = p.router.cfg.Control.Success(p.payment.PaymentHash, result.Preimage)
if err != nil {
log.Errorf("Unable to succeed payment "+
"attempt: %v", err)
return [32]byte{}, nil, err
}
// Terminal state, return the preimage and the route
// taken.
return result.Preimage, &p.attempt.Route, 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, errNoPathFound, errMaxHopsExceeded,
errPrebuiltRouteTried:
return channeldb.FailureReasonNoRoute
case errInsufficientBalance:
return channeldb.FailureReasonInsufficientBalance
}
return channeldb.FailureReasonError
}
// createNewPaymentAttempt creates and stores a new payment attempt to the
// database.
func (p *paymentLifecycle) createNewPaymentAttempt() (lnwire.ShortChannelID,
*lnwire.UpdateAddHTLC, error) {
// 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.payment.PaymentHash, channeldb.FailureReasonTimeout,
)
if err != nil {
return lnwire.ShortChannelID{}, nil, err
}
errStr := fmt.Sprintf("payment attempt not completed " +
"before timeout")
return lnwire.ShortChannelID{}, nil,
newErr(ErrPaymentAttemptTimeout, errStr)
case <-p.router.quit:
// The payment will be resumed from the current state
// after restart.
return lnwire.ShortChannelID{}, nil, ErrRouterShuttingDown
default:
// Fall through if we haven't hit our time limit, or
// are expiring.
}
// Create a new payment attempt from the given payment session.
rt, err := p.paySession.RequestRoute(
p.payment, uint32(p.currentHeight), p.finalCLTVDelta,
)
if err != nil {
log.Warnf("Failed to find route for payment %x: %v",
p.payment.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.payment.PaymentHash, failure,
)
if saveErr != nil {
return lnwire.ShortChannelID{}, nil, saveErr
}
// If there was an error already recorded for this
// payment, we'll return that.
if p.lastError != nil {
return lnwire.ShortChannelID{}, nil,
errNoRoute{lastError: p.lastError}
}
// Terminal state, return.
return lnwire.ShortChannelID{}, nil, err
}
// Generate a new key to be used for this attempt.
sessionKey, err := generateNewSessionKey()
if err != nil {
return lnwire.ShortChannelID{}, nil, err
}
// Generate the raw encoded sphinx packet to be included along
// with the htlcAdd message that we send directly to the
// switch.
onionBlob, c, err := generateSphinxPacket(
rt, p.payment.PaymentHash[:], sessionKey,
)
// With SendToRoute, it can happen that the route exceeds protocol
// constraints. Mark the payment as failed with an internal error.
if err == route.ErrMaxRouteHopsExceeded ||
err == sphinx.ErrMaxRoutingInfoSizeExceeded {
log.Debugf("Invalid route provided for payment %x: %v",
p.payment.PaymentHash, err)
controlErr := p.router.cfg.Control.Fail(
p.payment.PaymentHash, channeldb.FailureReasonError,
)
if controlErr != nil {
return lnwire.ShortChannelID{}, nil, controlErr
}
}
// In any case, don't continue if there is an error.
if err != nil {
return lnwire.ShortChannelID{}, nil, err
}
// Update our cached circuit with the newly generated
// one.
p.circuit = c
// 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.payment.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.
paymentID, err := p.router.cfg.NextPaymentID()
if err != nil {
return lnwire.ShortChannelID{}, nil, err
}
// We now have all the information needed to populate
// the current attempt information.
p.attempt = &channeldb.PaymentAttemptInfo{
PaymentID: paymentID,
SessionKey: sessionKey,
Route: *rt,
}
// 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.payment.PaymentHash, p.attempt)
if err != nil {
return lnwire.ShortChannelID{}, nil, err
}
return firstHop, htlcAdd, nil
}
// sendPaymentAttempt attempts to send the current attempt to the switch.
func (p *paymentLifecycle) sendPaymentAttempt(firstHop lnwire.ShortChannelID,
htlcAdd *lnwire.UpdateAddHTLC) error {
log.Tracef("Attempting to send payment %x (pid=%v), "+
"using route: %v", p.payment.PaymentHash, p.attempt.PaymentID,
newLogClosure(func() string {
return spew.Sdump(p.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, p.attempt.PaymentID, htlcAdd,
)
if err != nil {
log.Errorf("Failed sending attempt %d for payment "+
"%x to switch: %v", p.attempt.PaymentID,
p.payment.PaymentHash, err)
return err
}
log.Debugf("Payment %x (pid=%v) successfully sent to switch, route: %v",
p.payment.PaymentHash, p.attempt.PaymentID, &p.attempt.Route)
return nil
}
// handleSendError inspects the given error from the Switch and determines
// whether we should make another payment attempt.
func (p *paymentLifecycle) handleSendError(sendErr error) error {
reason := p.router.processSendError(
p.attempt.PaymentID, &p.attempt.Route, sendErr,
)
if reason == nil {
// Save the forwarding error so it can be returned if
// this turns out to be the last attempt.
p.lastError = sendErr
return nil
}
log.Debugf("Payment %x failed: final_outcome=%v, raw_err=%v",
p.payment.PaymentHash, *reason, sendErr)
// Mark the payment failed with no route.
//
// TODO(halseth): make payment codes for the actual reason we don't
// continue path finding.
err := p.router.cfg.Control.Fail(
p.payment.PaymentHash, *reason,
)
if err != nil {
return err
}
// Terminal state, return the error we encountered.
return sendErr
}