7b318a4be7
This commit finally enables MP payments within the payment lifecycle (used for SendPayment). This is done by letting the loop launch shards as long as there is value remaining to send, inspecting the outcomes for the sent shards when the full payment amount has been filled. The method channeldb.MPPayment.SentAmt() is added to easily look up how much value we have sent for the payment.
769 lines
22 KiB
Go
769 lines
22 KiB
Go
package routing
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import (
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"fmt"
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"sync"
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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/lntypes"
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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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totalAmount lnwire.MilliSatoshi
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feeLimit lnwire.MilliSatoshi
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paymentHash lntypes.Hash
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paySession PaymentSession
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timeoutChan <-chan time.Time
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currentHeight int32
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}
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// payemntState holds a number of key insights learned from a given MPPayment
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// that we use to determine what to do on each payment loop iteration.
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type paymentState struct {
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numShardsInFlight int
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remainingAmt lnwire.MilliSatoshi
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remainingFees lnwire.MilliSatoshi
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terminate bool
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}
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// paymentState uses the passed payment to find the latest information we need
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// to act on every iteration of the payment loop.
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func (p *paymentLifecycle) paymentState(payment *channeldb.MPPayment) (
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*paymentState, error) {
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// Fetch the total amount and fees that has already been sent in
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// settled and still in-flight shards.
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sentAmt, fees := payment.SentAmt()
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// Sanity check we haven't sent a value larger than the payment amount.
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if sentAmt > p.totalAmount {
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return nil, fmt.Errorf("amount sent %v exceeds "+
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"total amount %v", sentAmt, p.totalAmount)
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}
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// We'll subtract the used fee from our fee budget, but allow the fees
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// of the already sent shards to exceed our budget (can happen after
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// restarts).
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feeBudget := p.feeLimit
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if fees <= feeBudget {
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feeBudget -= fees
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} else {
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feeBudget = 0
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}
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// Get any terminal info for this payment.
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settle, failure := payment.TerminalInfo()
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// If either an HTLC settled, or the payment has a payment level
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// failure recorded, it means we should terminate the moment all shards
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// have returned with a result.
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terminate := settle != nil || failure != nil
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activeShards := payment.InFlightHTLCs()
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return &paymentState{
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numShardsInFlight: len(activeShards),
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remainingAmt: p.totalAmount - sentAmt,
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remainingFees: feeBudget,
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terminate: terminate,
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}, nil
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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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shardHandler := &shardHandler{
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router: p.router,
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paymentHash: p.paymentHash,
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shardErrors: make(chan error),
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quit: make(chan struct{}),
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}
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// When the payment lifecycle loop exits, we make sure to signal any
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// sub goroutine of the shardHandler to exit, then wait for them to
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// return.
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defer shardHandler.stop()
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// If we had any existing attempts outstanding, we'll start by spinning
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// up goroutines that'll collect their results and deliver them to the
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// lifecycle loop below.
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payment, err := p.router.cfg.Control.FetchPayment(
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p.paymentHash,
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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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for _, a := range payment.InFlightHTLCs() {
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a := a
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log.Debugf("Resuming payment shard %v for hash %v",
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a.AttemptID, p.paymentHash)
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shardHandler.collectResultAsync(&a.HTLCAttemptInfo)
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}
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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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// Start by quickly checking if there are any outcomes already
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// available to handle before we reevaluate our state.
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if err := shardHandler.checkShards(); err != nil {
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return [32]byte{}, nil, err
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}
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// We start every iteration by fetching the lastest state of
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// the payment from the ControlTower. This ensures that we will
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// act on the latest available information, whether we are
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// resuming an existing payment or just sent a new attempt.
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payment, err := p.router.cfg.Control.FetchPayment(
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p.paymentHash,
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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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// Using this latest state of the payment, calculate
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// information about our active shards and terminal conditions.
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state, err := p.paymentState(payment)
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if err != nil {
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return [32]byte{}, nil, err
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}
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log.Debugf("Payment %v in state terminate=%v, "+
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"active_shards=%v, rem_value=%v, fee_limit=%v",
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p.paymentHash, state.terminate, state.numShardsInFlight,
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state.remainingAmt, state.remainingFees)
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switch {
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// We have a terminal condition and no active shards, we are
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// ready to exit.
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case state.terminate && state.numShardsInFlight == 0:
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// Find the first successful shard and return
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// the preimage and route.
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for _, a := range payment.HTLCs {
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if a.Settle != nil {
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return a.Settle.Preimage, &a.Route, nil
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}
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}
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// Payment failed.
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return [32]byte{}, nil, *payment.FailureReason
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// If we either reached a terminal error condition (but had
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// active shards still) or there is no remaining value to send,
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// we'll wait for a shard outcome.
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case state.terminate || state.remainingAmt == 0:
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// We still have outstanding shards, so wait for a new
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// outcome to be available before re-evaluating our
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// state.
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if err := shardHandler.waitForShard(); err != nil {
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return [32]byte{}, nil, err
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}
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continue
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}
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// Before we attempt any new shard, 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. If a timeout is not applicable, timeoutChan
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// will be nil.
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select {
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case <-p.timeoutChan:
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log.Warnf("payment attempt not completed before " +
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"timeout")
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// By marking the payment failed with the control
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// tower, no further shards will be launched and we'll
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// return with an error the moment all active shards
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// have finished.
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saveErr := p.router.cfg.Control.Fail(
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p.paymentHash, channeldb.FailureReasonTimeout,
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)
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if saveErr != nil {
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return [32]byte{}, nil, saveErr
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}
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continue
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case <-p.router.quit:
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return [32]byte{}, nil, ErrRouterShuttingDown
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// Fall through if we haven't hit our time limit.
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default:
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}
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// Create a new payment attempt from the given payment session.
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rt, err := p.paySession.RequestRoute(
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state.remainingAmt, state.remainingFees,
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uint32(state.numShardsInFlight), uint32(p.currentHeight),
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)
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if err != nil {
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log.Warnf("Failed to find route for payment %x: %v",
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p.paymentHash, err)
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// There is no route to try, and we have no active
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// shards. This means that there is no way for us to
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// send the payment, so mark it failed with no route.
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if state.numShardsInFlight == 0 {
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failureCode := errorToPaymentFailure(err)
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log.Debugf("Marking payment %v permanently "+
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"failed with no route: %v",
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p.paymentHash, failureCode)
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saveErr := p.router.cfg.Control.Fail(
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p.paymentHash, failureCode,
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)
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if saveErr != nil {
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return [32]byte{}, nil, saveErr
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}
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continue
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}
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// We still have active shards, we'll wait for an
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// outcome to be available before retrying.
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if err := shardHandler.waitForShard(); err != nil {
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return [32]byte{}, nil, err
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}
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continue
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}
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// We found a route to try, launch a new shard.
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attempt, outcome, err := shardHandler.launchShard(rt)
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if err != nil {
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return [32]byte{}, nil, err
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}
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// If we encountered a non-critical error when launching the
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// shard, handle it.
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if outcome.err != nil {
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log.Warnf("Failed to launch shard %v for "+
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"payment %v: %v", attempt.AttemptID,
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p.paymentHash, outcome.err)
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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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err := shardHandler.handleSendError(
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attempt, outcome.err,
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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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// Error was handled successfully, continue to make a
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// new attempt.
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continue
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}
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// Now that the shard was successfully sent, launch a go
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// routine that will handle its result when its back.
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shardHandler.collectResultAsync(attempt)
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}
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}
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// shardHandler holds what is necessary to send and collect the result of
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// shards.
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type shardHandler struct {
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paymentHash lntypes.Hash
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router *ChannelRouter
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// shardErrors is a channel where errors collected by calling
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// collectResultAsync will be delivered. These results are meant to be
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// inspected by calling waitForShard or checkShards, and the channel
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// doesn't need to be initiated if the caller is using the sync
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// collectResult directly.
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shardErrors chan error
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// quit is closed to signal the sub goroutines of the payment lifecycle
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// to stop.
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quit chan struct{}
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wg sync.WaitGroup
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}
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// stop signals any active shard goroutine to exit and waits for them to exit.
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func (p *shardHandler) stop() {
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close(p.quit)
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p.wg.Wait()
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}
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// waitForShard blocks until any of the outstanding shards return.
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func (p *shardHandler) waitForShard() error {
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select {
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case err := <-p.shardErrors:
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return err
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case <-p.quit:
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return fmt.Errorf("shard handler quitting")
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case <-p.router.quit:
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return ErrRouterShuttingDown
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}
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}
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// checkShards is a non-blocking method that check if any shards has finished
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// their execution.
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func (p *shardHandler) checkShards() error {
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for {
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select {
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case err := <-p.shardErrors:
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if err != nil {
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return err
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}
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case <-p.quit:
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return fmt.Errorf("shard handler quitting")
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case <-p.router.quit:
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return ErrRouterShuttingDown
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default:
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return nil
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}
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}
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}
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// launchOutcome is a type returned from launchShard that indicates whether the
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// shard was successfully send onto the network.
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type launchOutcome struct {
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// err is non-nil if a non-critical error was encountered when trying
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// to send the shard, and we successfully updated the control tower to
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// reflect this error. This can be errors like not enough local
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// balance for the given route etc.
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err error
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}
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// launchShard creates and sends an HTLC attempt along the given route,
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// registering it with the control tower before sending it. It returns the
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// HTLCAttemptInfo that was created for the shard, along with a launchOutcome.
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// The launchOutcome is used to indicate whether the attempt was successfully
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// sent. If the launchOutcome wraps a non-nil error, it means that the attempt
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// was not sent onto the network, so no result will be available in the future
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// for it.
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func (p *shardHandler) launchShard(rt *route.Route) (*channeldb.HTLCAttemptInfo,
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*launchOutcome, error) {
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// Using the route received from the payment session, create a new
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// shard to send.
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firstHop, htlcAdd, attempt, err := p.createNewPaymentAttempt(
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rt,
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)
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if err != nil {
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return nil, nil, err
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}
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// Before sending this HTLC to the switch, we checkpoint the fresh
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// paymentID and route to the DB. This lets us know on startup the ID
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// of the payment that we attempted to send, such that we can query the
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// Switch for its whereabouts. The route is needed to handle the result
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// when it eventually comes back.
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err = p.router.cfg.Control.RegisterAttempt(p.paymentHash, attempt)
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if err != nil {
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return nil, nil, err
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}
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// Now that the attempt is created and checkpointed to the DB, we send
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// it.
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sendErr := p.sendPaymentAttempt(attempt, firstHop, htlcAdd)
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if sendErr != nil {
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// TODO(joostjager): Distinguish unexpected internal errors
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// from real send errors.
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err := p.failAttempt(attempt, sendErr)
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if err != nil {
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return nil, nil, err
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}
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// Return a launchOutcome indicating the shard failed.
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return attempt, &launchOutcome{
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err: sendErr,
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}, nil
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}
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return attempt, &launchOutcome{}, nil
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}
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// shardResult holds the resulting outcome of a shard sent.
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type shardResult struct {
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// preimage is the payment preimage in case of a settled HTLC. Only set
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// if err is non-nil.
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preimage lntypes.Preimage
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// err indicates that the shard failed.
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err error
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}
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// collectResultAsync launches a goroutine that will wait for the result of the
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// given HTLC attempt to be available then handle its result. Note that it will
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// fail the payment with the control tower if a terminal error is encountered.
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func (p *shardHandler) collectResultAsync(attempt *channeldb.HTLCAttemptInfo) {
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p.wg.Add(1)
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go func() {
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defer p.wg.Done()
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// Block until the result is available.
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result, err := p.collectResult(attempt)
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if err != nil {
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if err != ErrRouterShuttingDown &&
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err != htlcswitch.ErrSwitchExiting {
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log.Errorf("Error collecting result for "+
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"shard %v for payment %v: %v",
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attempt.AttemptID, p.paymentHash, err)
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}
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select {
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case p.shardErrors <- err:
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case <-p.router.quit:
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case <-p.quit:
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}
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return
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}
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// If a non-critical error was encountered handle it and mark
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// the payment failed if the failure was terminal.
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if result.err != nil {
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err := p.handleSendError(attempt, result.err)
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if err != nil {
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select {
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case p.shardErrors <- err:
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case <-p.router.quit:
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case <-p.quit:
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}
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return
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}
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}
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select {
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case p.shardErrors <- nil:
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case <-p.router.quit:
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case <-p.quit:
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}
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}()
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}
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// collectResult waits for the result for the given attempt to be available
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// from the Switch, then records the attempt outcome with the control tower. A
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// shardResult is returned, indicating the final outcome of this HTLC attempt.
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func (p *shardHandler) collectResult(attempt *channeldb.HTLCAttemptInfo) (
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*shardResult, error) {
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// Regenerate the circuit for this attempt.
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_, circuit, err := generateSphinxPacket(
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&attempt.Route, p.paymentHash[:],
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attempt.SessionKey,
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)
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if err != nil {
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return nil, err
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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(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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attempt.AttemptID, p.paymentHash, errorDecryptor,
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)
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switch {
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// If this attempt ID is unknown to the Switch, it means it was never
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// checkpointed and forwarded by the switch before a restart. In this
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// case we can safely send a new payment attempt, and wait for its
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// 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.", attempt.AttemptID,
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p.paymentHash)
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cErr := p.failAttempt(attempt, err)
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if cErr != nil {
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return nil, cErr
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}
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return &shardResult{
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err: err,
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}, nil
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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 attemptID %d "+
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"from switch: %v", attempt.AttemptID, err)
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return nil, err
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}
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|
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// The switch knows about this payment, we'll wait for a result to be
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// 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 nil, htlcswitch.ErrSwitchExiting
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}
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|
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case <-p.router.quit:
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return nil, ErrRouterShuttingDown
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|
|
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case <-p.quit:
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return nil, fmt.Errorf("shard handler exiting")
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}
|
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|
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// In case of a payment failure, fail the attempt with the control
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// tower and return.
|
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if result.Error != nil {
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err := p.failAttempt(attempt, result.Error)
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if err != nil {
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return nil, err
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}
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return &shardResult{
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err: result.Error,
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}, nil
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}
|
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|
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// We successfully got a payment result back from the switch.
|
|
log.Debugf("Payment %x succeeded with pid=%v",
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|
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
|
|
|
|
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 {
|
|
|
|
log.Warnf("Attempt %v for payment %v failed: %v", attempt.AttemptID,
|
|
p.paymentHash, sendError)
|
|
|
|
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
|
|
}
|