355 lines
10 KiB
Go
355 lines
10 KiB
Go
package routing
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import (
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"fmt"
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"time"
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"github.com/davecgh/go-spew/spew"
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sphinx "github.com/lightningnetwork/lightning-onion"
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"github.com/lightningnetwork/lnd/channeldb"
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"github.com/lightningnetwork/lnd/htlcswitch"
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"github.com/lightningnetwork/lnd/lnwire"
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"github.com/lightningnetwork/lnd/routing/route"
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)
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// paymentLifecycle holds all information about the current state of a payment
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// needed to resume if from any point.
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type paymentLifecycle struct {
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router *ChannelRouter
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payment *LightningPayment
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paySession PaymentSession
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timeoutChan <-chan time.Time
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currentHeight int32
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finalCLTVDelta uint16
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attempt *channeldb.PaymentAttemptInfo
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circuit *sphinx.Circuit
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lastError error
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}
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// resumePayment resumes the paymentLifecycle from the current state.
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func (p *paymentLifecycle) resumePayment() ([32]byte, *route.Route, error) {
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// We'll continue until either our payment succeeds, or we encounter a
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// critical error during path finding.
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for {
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// If this payment had no existing payment attempt, we create
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// and send one now.
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if p.attempt == nil {
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firstHop, htlcAdd, err := p.createNewPaymentAttempt()
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if err != nil {
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return [32]byte{}, nil, err
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}
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// Now that the attempt is created and checkpointed to
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// the DB, we send it.
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sendErr := p.sendPaymentAttempt(firstHop, htlcAdd)
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if sendErr != nil {
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// We must inspect the error to know whether it
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// was critical or not, to decide whether we
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// should continue trying.
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err := p.handleSendError(sendErr)
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if err != nil {
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return [32]byte{}, nil, err
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}
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// Error was handled successfully, reset the
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// attempt to indicate we want to make a new
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// attempt.
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p.attempt = nil
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continue
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}
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} else {
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// If this was a resumed attempt, we must regenerate the
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// circuit.
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_, c, err := generateSphinxPacket(
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&p.attempt.Route, p.payment.PaymentHash[:],
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p.attempt.SessionKey,
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)
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if err != nil {
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return [32]byte{}, nil, err
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}
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p.circuit = c
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}
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// Using the created circuit, initialize the error decrypter so we can
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// parse+decode any failures incurred by this payment within the
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// switch.
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errorDecryptor := &htlcswitch.SphinxErrorDecrypter{
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OnionErrorDecrypter: sphinx.NewOnionErrorDecrypter(p.circuit),
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}
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// Now ask the switch to return the result of the payment when
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// available.
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resultChan, err := p.router.cfg.Payer.GetPaymentResult(
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p.attempt.PaymentID, errorDecryptor,
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)
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switch {
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// If this payment ID is unknown to the Switch, it means it was
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// never checkpointed and forwarded by the switch before a
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// restart. In this case we can safely send a new payment
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// attempt, and wait for its result to be available.
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case err == htlcswitch.ErrPaymentIDNotFound:
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log.Debugf("Payment ID %v for hash %x not found in "+
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"the Switch, retrying.", p.attempt.PaymentID,
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p.payment.PaymentHash)
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// Reset the attempt to indicate we want to make a new
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// attempt.
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p.attempt = nil
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continue
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// A critical, unexpected error was encountered.
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case err != nil:
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log.Errorf("Failed getting result for paymentID %d "+
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"from switch: %v", p.attempt.PaymentID, err)
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return [32]byte{}, nil, err
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}
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// The switch knows about this payment, we'll wait for a result
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// to be available.
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var (
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result *htlcswitch.PaymentResult
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ok bool
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)
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select {
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case result, ok = <-resultChan:
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if !ok {
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return [32]byte{}, nil, htlcswitch.ErrSwitchExiting
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}
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case <-p.router.quit:
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return [32]byte{}, nil, ErrRouterShuttingDown
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}
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// In case of a payment failure, we use the error to decide
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// whether we should retry.
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if result.Error != nil {
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log.Errorf("Attempt to send payment %x failed: %v",
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p.payment.PaymentHash, result.Error)
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// We must inspect the error to know whether it was
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// critical or not, to decide whether we should
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// continue trying.
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if err := p.handleSendError(result.Error); err != nil {
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return [32]byte{}, nil, err
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}
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// Error was handled successfully, reset the attempt to
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// indicate we want to make a new attempt.
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p.attempt = nil
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continue
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}
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// We successfully got a payment result back from the switch.
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log.Debugf("Payment %x succeeded with pid=%v",
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p.payment.PaymentHash, p.attempt.PaymentID)
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// In case of success we atomically store the db payment and
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// move the payment to the success state.
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err = p.router.cfg.Control.Success(p.payment.PaymentHash, result.Preimage)
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if err != nil {
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log.Errorf("Unable to succeed payment "+
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"attempt: %v", err)
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return [32]byte{}, nil, err
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}
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// Terminal state, return the preimage and the route
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// taken.
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return result.Preimage, &p.attempt.Route, nil
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}
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}
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// createNewPaymentAttempt creates and stores a new payment attempt to the
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// database.
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func (p *paymentLifecycle) createNewPaymentAttempt() (lnwire.ShortChannelID,
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*lnwire.UpdateAddHTLC, error) {
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// Before we attempt this next payment, we'll check to see if
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// either we've gone past the payment attempt timeout, or the
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// router is exiting. In either case, we'll stop this payment
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// attempt short.
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select {
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case <-p.timeoutChan:
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// Mark the payment as failed because of the
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// timeout.
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err := p.router.cfg.Control.Fail(
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p.payment.PaymentHash,
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)
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if err != nil {
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return lnwire.ShortChannelID{}, nil, err
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}
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errStr := fmt.Sprintf("payment attempt not completed " +
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"before timeout")
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return lnwire.ShortChannelID{}, nil,
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newErr(ErrPaymentAttemptTimeout, errStr)
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case <-p.router.quit:
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// The payment will be resumed from the current state
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// after restart.
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return lnwire.ShortChannelID{}, nil, ErrRouterShuttingDown
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default:
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// Fall through if we haven't hit our time limit, or
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// are expiring.
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}
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// Create a new payment attempt from the given payment session.
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route, err := p.paySession.RequestRoute(
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p.payment, uint32(p.currentHeight), p.finalCLTVDelta,
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)
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if err != nil {
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// If we're unable to successfully make a payment using
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// any of the routes we've found, then mark the payment
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// as permanently failed.
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saveErr := p.router.cfg.Control.Fail(
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p.payment.PaymentHash,
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)
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if saveErr != nil {
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return lnwire.ShortChannelID{}, nil, saveErr
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}
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// If there was an error already recorded for this
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// payment, we'll return that.
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if p.lastError != nil {
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return lnwire.ShortChannelID{}, nil,
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fmt.Errorf("unable to route payment to "+
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"destination: %v", p.lastError)
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}
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// Terminal state, return.
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return lnwire.ShortChannelID{}, nil, err
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}
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// Generate a new key to be used for this attempt.
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sessionKey, err := generateNewSessionKey()
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if err != nil {
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return lnwire.ShortChannelID{}, nil, err
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}
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// Generate the raw encoded sphinx packet to be included along
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// with the htlcAdd message that we send directly to the
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// switch.
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onionBlob, c, err := generateSphinxPacket(
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route, p.payment.PaymentHash[:], sessionKey,
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)
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if err != nil {
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return lnwire.ShortChannelID{}, nil, err
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}
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// Update our cached circuit with the newly generated
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// one.
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p.circuit = c
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// Craft an HTLC packet to send to the layer 2 switch. The
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// metadata within this packet will be used to route the
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// payment through the network, starting with the first-hop.
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htlcAdd := &lnwire.UpdateAddHTLC{
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Amount: route.TotalAmount,
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Expiry: route.TotalTimeLock,
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PaymentHash: p.payment.PaymentHash,
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}
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copy(htlcAdd.OnionBlob[:], onionBlob)
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// Attempt to send this payment through the network to complete
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// the payment. If this attempt fails, then we'll continue on
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// to the next available route.
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firstHop := lnwire.NewShortChanIDFromInt(
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route.Hops[0].ChannelID,
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)
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// We generate a new, unique payment ID that we will use for
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// this HTLC.
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paymentID, err := p.router.cfg.NextPaymentID()
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if err != nil {
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return lnwire.ShortChannelID{}, nil, err
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}
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// We now have all the information needed to populate
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// the current attempt information.
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p.attempt = &channeldb.PaymentAttemptInfo{
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PaymentID: paymentID,
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SessionKey: sessionKey,
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Route: *route,
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}
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// Before sending this HTLC to the switch, we checkpoint the
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// fresh paymentID and route to the DB. This lets us know on
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// startup the ID of the payment that we attempted to send,
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// such that we can query the Switch for its whereabouts. The
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// route is needed to handle the result when it eventually
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// comes back.
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err = p.router.cfg.Control.RegisterAttempt(p.payment.PaymentHash, p.attempt)
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if err != nil {
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return lnwire.ShortChannelID{}, nil, err
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}
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return firstHop, htlcAdd, nil
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}
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// sendPaymentAttempt attempts to send the current attempt to the switch.
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func (p *paymentLifecycle) sendPaymentAttempt(firstHop lnwire.ShortChannelID,
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htlcAdd *lnwire.UpdateAddHTLC) error {
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log.Tracef("Attempting to send payment %x (pid=%v), "+
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"using route: %v", p.payment.PaymentHash, p.attempt.PaymentID,
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newLogClosure(func() string {
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return spew.Sdump(p.attempt.Route)
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}),
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)
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// Send it to the Switch. When this method returns we assume
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// the Switch successfully has persisted the payment attempt,
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// such that we can resume waiting for the result after a
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// restart.
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err := p.router.cfg.Payer.SendHTLC(
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firstHop, p.attempt.PaymentID, htlcAdd,
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)
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if err != nil {
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log.Errorf("Failed sending attempt %d for payment "+
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"%x to switch: %v", p.attempt.PaymentID,
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p.payment.PaymentHash, err)
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return err
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}
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log.Debugf("Payment %x (pid=%v) successfully sent to switch",
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p.payment.PaymentHash, p.attempt.PaymentID)
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return nil
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}
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// handleSendError inspects the given error from the Switch and determines
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// whether we should make another payment attempt.
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func (p *paymentLifecycle) handleSendError(sendErr error) error {
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finalOutcome := p.router.processSendError(
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p.paySession, &p.attempt.Route, sendErr,
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)
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if finalOutcome {
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log.Errorf("Payment %x failed with final outcome: %v",
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p.payment.PaymentHash, sendErr)
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// Mark the payment failed with no route.
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// TODO(halseth): make payment codes for the actual reason we
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// don't continue path finding.
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err := p.router.cfg.Control.Fail(
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p.payment.PaymentHash,
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)
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if err != nil {
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return err
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}
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// Terminal state, return the error we encountered.
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return sendErr
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}
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// We get ready to make another payment attempt.
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p.lastError = sendErr
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return nil
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}
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