package routing
import (
"bytes"
"fmt"
"runtime"
"sync"
"sync/atomic"
"time"
"github.com/btcsuite/btcd/btcec"
"github.com/btcsuite/btcd/wire"
"github.com/btcsuite/btcutil"
"github.com/davecgh/go-spew/spew"
"github.com/go-errors/errors"
sphinx "github.com/lightningnetwork/lightning-onion"
"github.com/lightningnetwork/lnd/channeldb"
"github.com/lightningnetwork/lnd/channeldb/kvdb"
"github.com/lightningnetwork/lnd/clock"
"github.com/lightningnetwork/lnd/htlcswitch"
"github.com/lightningnetwork/lnd/input"
"github.com/lightningnetwork/lnd/lntypes"
"github.com/lightningnetwork/lnd/lnwallet"
"github.com/lightningnetwork/lnd/lnwallet/chanvalidate"
"github.com/lightningnetwork/lnd/lnwire"
"github.com/lightningnetwork/lnd/multimutex"
"github.com/lightningnetwork/lnd/record"
"github.com/lightningnetwork/lnd/routing/chainview"
"github.com/lightningnetwork/lnd/routing/route"
"github.com/lightningnetwork/lnd/ticker"
"github.com/lightningnetwork/lnd/zpay32"
)
const (
// DefaultPayAttemptTimeout is the default payment attempt timeout. The
// payment attempt timeout defines the duration after which we stop
// trying more routes for a payment.
DefaultPayAttemptTimeout = time.Duration(time.Second * 60)
// DefaultChannelPruneExpiry is the default duration used to determine
// if a channel should be pruned or not.
DefaultChannelPruneExpiry = time.Duration(time.Hour * 24 * 14)
// defaultStatInterval governs how often the router will log non-empty
// stats related to processing new channels, updates, or node
// announcements.
defaultStatInterval = time.Minute
)
var (
// ErrRouterShuttingDown is returned if the router is in the process of
// shutting down.
ErrRouterShuttingDown = fmt.Errorf("router shutting down")
)
// ChannelGraphSource represents the source of information about the topology
// of the lightning network. It's responsible for the addition of nodes, edges,
// applying edge updates, and returning the current block height with which the
// topology is synchronized.
type ChannelGraphSource interface {
// AddNode is used to add information about a node to the router
// database. If the node with this pubkey is not present in an existing
// channel, it will be ignored.
AddNode(node *channeldb.LightningNode) error
// AddEdge is used to add edge/channel to the topology of the router,
// after all information about channel will be gathered this
// edge/channel might be used in construction of payment path.
AddEdge(edge *channeldb.ChannelEdgeInfo) error
// AddProof updates the channel edge info with proof which is needed to
// properly announce the edge to the rest of the network.
AddProof(chanID lnwire.ShortChannelID, proof *channeldb.ChannelAuthProof) error
// UpdateEdge is used to update edge information, without this message
// edge considered as not fully constructed.
UpdateEdge(policy *channeldb.ChannelEdgePolicy) error
// IsStaleNode returns true if the graph source has a node announcement
// for the target node with a more recent timestamp. This method will
// also return true if we don't have an active channel announcement for
// the target node.
IsStaleNode(node route.Vertex, timestamp time.Time) bool
// IsPublicNode determines whether the given vertex is seen as a public
// node in the graph from the graph's source node's point of view.
IsPublicNode(node route.Vertex) (bool, error)
// IsKnownEdge returns true if the graph source already knows of the
// passed channel ID either as a live or zombie edge.
IsKnownEdge(chanID lnwire.ShortChannelID) bool
// IsStaleEdgePolicy returns true if the graph source has a channel
// edge for the passed channel ID (and flags) that have a more recent
// timestamp.
IsStaleEdgePolicy(chanID lnwire.ShortChannelID, timestamp time.Time,
flags lnwire.ChanUpdateChanFlags) bool
// MarkEdgeLive clears an edge from our zombie index, deeming it as
// live.
MarkEdgeLive(chanID lnwire.ShortChannelID) error
// ForAllOutgoingChannels is used to iterate over all channels
// emanating from the "source" node which is the center of the
// star-graph.
ForAllOutgoingChannels(cb func(c *channeldb.ChannelEdgeInfo,
e *channeldb.ChannelEdgePolicy) error) error
// CurrentBlockHeight returns the block height from POV of the router
// subsystem.
CurrentBlockHeight() (uint32, error)
// GetChannelByID return the channel by the channel id.
GetChannelByID(chanID lnwire.ShortChannelID) (*channeldb.ChannelEdgeInfo,
*channeldb.ChannelEdgePolicy, *channeldb.ChannelEdgePolicy, error)
// FetchLightningNode attempts to look up a target node by its identity
// public key. channeldb.ErrGraphNodeNotFound is returned if the node
// doesn't exist within the graph.
FetchLightningNode(route.Vertex) (*channeldb.LightningNode, error)
// ForEachNode is used to iterate over every node in the known graph.
ForEachNode(func(node *channeldb.LightningNode) error) error
// ForEachChannel is used to iterate over every channel in the known
// graph.
ForEachChannel(func(chanInfo *channeldb.ChannelEdgeInfo,
e1, e2 *channeldb.ChannelEdgePolicy) error) error
}
// PaymentAttemptDispatcher is used by the router to send payment attempts onto
// the network, and receive their results.
type PaymentAttemptDispatcher interface {
// SendHTLC is a function that directs a link-layer switch to
// forward a fully encoded payment to the first hop in the route
// denoted by its public key. A non-nil error is to be returned if the
// payment was unsuccessful.
SendHTLC(firstHop lnwire.ShortChannelID,
paymentID uint64,
htlcAdd *lnwire.UpdateAddHTLC) error
// GetPaymentResult returns the the result of the payment attempt with
// the given paymentID. The method returns a channel where the payment
// result will be sent when available, or an error is encountered
// during forwarding. When a result is received on the channel, the
// HTLC is guaranteed to no longer be in flight. The switch shutting
// down is signaled by closing the channel. If the paymentID is
// unknown, ErrPaymentIDNotFound will be returned.
GetPaymentResult(paymentID uint64, paymentHash lntypes.Hash,
deobfuscator htlcswitch.ErrorDecrypter) (
<-chan *htlcswitch.PaymentResult, error)
}
// PaymentSessionSource is an interface that defines a source for the router to
// retrive new payment sessions.
type PaymentSessionSource interface {
// NewPaymentSession creates a new payment session that will produce
// routes to the given target. An optional set of routing hints can be
// provided in order to populate additional edges to explore when
// finding a path to the payment's destination.
NewPaymentSession(p *LightningPayment) (PaymentSession, error)
// NewPaymentSessionEmpty creates a new paymentSession instance that is
// empty, and will be exhausted immediately. Used for failure reporting
// to missioncontrol for resumed payment we don't want to make more
// attempts for.
NewPaymentSessionEmpty() PaymentSession
}
// MissionController is an interface that exposes failure reporting and
// probability estimation.
type MissionController interface {
// ReportPaymentFail reports a failed payment to mission control as
// input for future probability estimates. It returns a bool indicating
// whether this error is a final error and no further payment attempts
// need to be made.
ReportPaymentFail(paymentID uint64, rt *route.Route,
failureSourceIdx *int, failure lnwire.FailureMessage) (
*channeldb.FailureReason, error)
// ReportPaymentSuccess reports a successful payment to mission control as input
// for future probability estimates.
ReportPaymentSuccess(paymentID uint64, rt *route.Route) error
// GetProbability is expected to return the success probability of a
// payment from fromNode along edge.
GetProbability(fromNode, toNode route.Vertex,
amt lnwire.MilliSatoshi) float64
}
// FeeSchema is the set fee configuration for a Lightning Node on the network.
// Using the coefficients described within the schema, the required fee to
// forward outgoing payments can be derived.
type FeeSchema struct {
// BaseFee is the base amount of milli-satoshis that will be chained
// for ANY payment forwarded.
BaseFee lnwire.MilliSatoshi
// FeeRate is the rate that will be charged for forwarding payments.
// This value should be interpreted as the numerator for a fraction
// (fixed point arithmetic) whose denominator is 1 million. As a result
// the effective fee rate charged per mSAT will be: (amount *
// FeeRate/1,000,000).
FeeRate uint32
}
// ChannelPolicy holds the parameters that determine the policy we enforce
// when forwarding payments on a channel. These parameters are communicated
// to the rest of the network in ChannelUpdate messages.
type ChannelPolicy struct {
// FeeSchema holds the fee configuration for a channel.
FeeSchema
// TimeLockDelta is the required HTLC timelock delta to be used
// when forwarding payments.
TimeLockDelta uint32
// MaxHTLC is the maximum HTLC size including fees we are allowed to
// forward over this channel.
MaxHTLC lnwire.MilliSatoshi
// MinHTLC is the minimum HTLC size including fees we are allowed to
// forward over this channel.
MinHTLC *lnwire.MilliSatoshi
}
// Config defines the configuration for the ChannelRouter. ALL elements within
// the configuration MUST be non-nil for the ChannelRouter to carry out its
// duties.
type Config struct {
// Graph is the channel graph that the ChannelRouter will use to gather
// metrics from and also to carry out path finding queries.
// TODO(roasbeef): make into an interface
Graph *channeldb.ChannelGraph
// Chain is the router's source to the most up-to-date blockchain data.
// All incoming advertised channels will be checked against the chain
// to ensure that the channels advertised are still open.
Chain lnwallet.BlockChainIO
// ChainView is an instance of a FilteredChainView which is used to
// watch the sub-set of the UTXO set (the set of active channels) that
// we need in order to properly maintain the channel graph.
ChainView chainview.FilteredChainView
// Payer is an instance of a PaymentAttemptDispatcher and is used by
// the router to send payment attempts onto the network, and receive
// their results.
Payer PaymentAttemptDispatcher
// Control keeps track of the status of ongoing payments, ensuring we
// can properly resume them across restarts.
Control ControlTower
// MissionControl is a shared memory of sorts that executions of
// payment path finding use in order to remember which vertexes/edges
// were pruned from prior attempts. During SendPayment execution,
// errors sent by nodes are mapped into a vertex or edge to be pruned.
// Each run will then take into account this set of pruned
// vertexes/edges to reduce route failure and pass on graph information
// gained to the next execution.
MissionControl MissionController
// SessionSource defines a source for the router to retrieve new payment
// sessions.
SessionSource PaymentSessionSource
// ChannelPruneExpiry is the duration used to determine if a channel
// should be pruned or not. If the delta between now and when the
// channel was last updated is greater than ChannelPruneExpiry, then
// the channel is marked as a zombie channel eligible for pruning.
ChannelPruneExpiry time.Duration
// GraphPruneInterval is used as an interval to determine how often we
// should examine the channel graph to garbage collect zombie channels.
GraphPruneInterval time.Duration
// QueryBandwidth is a method that allows the router to query the lower
// link layer to determine the up to date available bandwidth at a
// prospective link to be traversed. If the link isn't available, then
// a value of zero should be returned. Otherwise, the current up to
// date knowledge of the available bandwidth of the link should be
// returned.
QueryBandwidth func(edge *channeldb.ChannelEdgeInfo) lnwire.MilliSatoshi
// NextPaymentID is a method that guarantees to return a new, unique ID
// each time it is called. This is used by the router to generate a
// unique payment ID for each payment it attempts to send, such that
// the switch can properly handle the HTLC.
NextPaymentID func() (uint64, error)
// AssumeChannelValid toggles whether or not the router will check for
// spentness of channel outpoints. For neutrino, this saves long rescans
// from blocking initial usage of the daemon.
AssumeChannelValid bool
// PathFindingConfig defines global path finding parameters.
PathFindingConfig PathFindingConfig
// Clock is mockable time provider.
Clock clock.Clock
}
// EdgeLocator is a struct used to identify a specific edge.
type EdgeLocator struct {
// ChannelID is the channel of this edge.
ChannelID uint64
// Direction takes the value of 0 or 1 and is identical in definition to
// the channel direction flag. A value of 0 means the direction from the
// lower node pubkey to the higher.
Direction uint8
}
// String returns a human readable version of the edgeLocator values.
func (e *EdgeLocator) String() string {
return fmt.Sprintf("%v:%v", e.ChannelID, e.Direction)
}
// ChannelRouter is the layer 3 router within the Lightning stack. Below the
// ChannelRouter is the HtlcSwitch, and below that is the Bitcoin blockchain
// itself. The primary role of the ChannelRouter is to respond to queries for
// potential routes that can support a payment amount, and also general graph
// reachability questions. The router will prune the channel graph
// automatically as new blocks are discovered which spend certain known funding
// outpoints, thereby closing their respective channels.
type ChannelRouter struct {
ntfnClientCounter uint64 // To be used atomically.
started uint32 // To be used atomically.
stopped uint32 // To be used atomically.
bestHeight uint32 // To be used atomically.
// cfg is a copy of the configuration struct that the ChannelRouter was
// initialized with.
cfg *Config
// selfNode is the center of the star-graph centered around the
// ChannelRouter. The ChannelRouter uses this node as a starting point
// when doing any path finding.
selfNode *channeldb.LightningNode
// newBlocks is a channel in which new blocks connected to the end of
// the main chain are sent over, and blocks updated after a call to
// UpdateFilter.
newBlocks <-chan *chainview.FilteredBlock
// staleBlocks is a channel in which blocks disconnected fromt the end
// of our currently known best chain are sent over.
staleBlocks <-chan *chainview.FilteredBlock
// networkUpdates is a channel that carries new topology updates
// messages from outside the ChannelRouter to be processed by the
// networkHandler.
networkUpdates chan *routingMsg
// topologyClients maps a client's unique notification ID to a
// topologyClient client that contains its notification dispatch
// channel.
topologyClients map[uint64]*topologyClient
// ntfnClientUpdates is a channel that's used to send new updates to
// topology notification clients to the ChannelRouter. Updates either
// add a new notification client, or cancel notifications for an
// existing client.
ntfnClientUpdates chan *topologyClientUpdate
// channelEdgeMtx is a mutex we use to make sure we process only one
// ChannelEdgePolicy at a time for a given channelID, to ensure
// consistency between the various database accesses.
channelEdgeMtx *multimutex.Mutex
// statTicker is a resumable ticker that logs the router's progress as
// it discovers channels or receives updates.
statTicker ticker.Ticker
// stats tracks newly processed channels, updates, and node
// announcements over a window of defaultStatInterval.
stats *routerStats
sync.RWMutex
quit chan struct{}
wg sync.WaitGroup
}
// A compile time check to ensure ChannelRouter implements the
// ChannelGraphSource interface.
var _ ChannelGraphSource = (*ChannelRouter)(nil)
// New creates a new instance of the ChannelRouter with the specified
// configuration parameters. As part of initialization, if the router detects
// that the channel graph isn't fully in sync with the latest UTXO (since the
// channel graph is a subset of the UTXO set) set, then the router will proceed
// to fully sync to the latest state of the UTXO set.
func New(cfg Config) (*ChannelRouter, error) {
selfNode, err := cfg.Graph.SourceNode()
if err != nil {
return nil, err
}
r := &ChannelRouter{
cfg: &cfg,
networkUpdates: make(chan *routingMsg),
topologyClients: make(map[uint64]*topologyClient),
ntfnClientUpdates: make(chan *topologyClientUpdate),
channelEdgeMtx: multimutex.NewMutex(),
selfNode: selfNode,
statTicker: ticker.New(defaultStatInterval),
stats: new(routerStats),
quit: make(chan struct{}),
}
return r, nil
}
// Start launches all the goroutines the ChannelRouter requires to carry out
// its duties. If the router has already been started, then this method is a
// noop.
func (r *ChannelRouter) Start() error {
if !atomic.CompareAndSwapUint32(&r.started, 0, 1) {
return nil
}
log.Tracef("Channel Router starting")
bestHash, bestHeight, err := r.cfg.Chain.GetBestBlock()
if err != nil {
return err
}
// If the graph has never been pruned, or hasn't fully been created yet,
// then we don't treat this as an explicit error.
if _, _, err := r.cfg.Graph.PruneTip(); err != nil {
switch {
case err == channeldb.ErrGraphNeverPruned:
fallthrough
case err == channeldb.ErrGraphNotFound:
// If the graph has never been pruned, then we'll set
// the prune height to the current best height of the
// chain backend.
_, err = r.cfg.Graph.PruneGraph(
nil, bestHash, uint32(bestHeight),
)
if err != nil {
return err
}
default:
return err
}
}
// If AssumeChannelValid is present, then we won't rely on pruning
// channels from the graph based on their spentness, but whether they
// are considered zombies or not.
if r.cfg.AssumeChannelValid {
if err := r.pruneZombieChans(); err != nil {
return err
}
} else {
// Otherwise, we'll use our filtered chain view to prune
// channels as soon as they are detected as spent on-chain.
if err := r.cfg.ChainView.Start(); err != nil {
return err
}
// Once the instance is active, we'll fetch the channel we'll
// receive notifications over.
r.newBlocks = r.cfg.ChainView.FilteredBlocks()
r.staleBlocks = r.cfg.ChainView.DisconnectedBlocks()
// Before we perform our manual block pruning, we'll construct
// and apply a fresh chain filter to the active
// FilteredChainView instance. We do this before, as otherwise
// we may miss on-chain events as the filter hasn't properly
// been applied.
channelView, err := r.cfg.Graph.ChannelView()
if err != nil && err != channeldb.ErrGraphNoEdgesFound {
return err
}
log.Infof("Filtering chain using %v channels active",
len(channelView))
if len(channelView) != 0 {
err = r.cfg.ChainView.UpdateFilter(
channelView, uint32(bestHeight),
)
if err != nil {
return err
}
}
// Before we begin normal operation of the router, we first need
// to synchronize the channel graph to the latest state of the
// UTXO set.
if err := r.syncGraphWithChain(); err != nil {
return err
}
// Finally, before we proceed, we'll prune any unconnected nodes
// from the graph in order to ensure we maintain a tight graph
// of "useful" nodes.
err = r.cfg.Graph.PruneGraphNodes()
if err != nil && err != channeldb.ErrGraphNodesNotFound {
return err
}
}
// If any payments are still in flight, we resume, to make sure their
// results are properly handled.
payments, err := r.cfg.Control.FetchInFlightPayments()
if err != nil {
return err
}
for _, payment := range payments {
log.Infof("Resuming payment with hash %v", payment.Info.PaymentHash)
r.wg.Add(1)
go func(payment *channeldb.InFlightPayment) {
defer r.wg.Done()
// We create a dummy, empty payment session such that
// we won't make another payment attempt when the
// result for the in-flight attempt is received.
paySession := r.cfg.SessionSource.NewPaymentSessionEmpty()
// We pass in a zero timeout value, to indicate we
// don't need it to timeout. It will stop immediately
// after the existing attempt has finished anyway. We
// also set a zero fee limit, as no more routes should
// be tried.
_, _, err := r.sendPayment(
payment.Info.Value, 0,
payment.Info.PaymentHash, 0, paySession,
)
if err != nil {
log.Errorf("Resuming payment with hash %v "+
"failed: %v.", payment.Info.PaymentHash, err)
return
}
log.Infof("Resumed payment with hash %v completed.",
payment.Info.PaymentHash)
}(payment)
}
r.wg.Add(1)
go r.networkHandler()
return nil
}
// Stop signals the ChannelRouter to gracefully halt all routines. This method
// will *block* until all goroutines have excited. If the channel router has
// already stopped then this method will return immediately.
func (r *ChannelRouter) Stop() error {
if !atomic.CompareAndSwapUint32(&r.stopped, 0, 1) {
return nil
}
log.Tracef("Channel Router shutting down")
// Our filtered chain view could've only been started if
// AssumeChannelValid isn't present.
if !r.cfg.AssumeChannelValid {
if err := r.cfg.ChainView.Stop(); err != nil {
return err
}
}
close(r.quit)
r.wg.Wait()
return nil
}
// syncGraphWithChain attempts to synchronize the current channel graph with
// the latest UTXO set state. This process involves pruning from the channel
// graph any channels which have been closed by spending their funding output
// since we've been down.
func (r *ChannelRouter) syncGraphWithChain() error {
// First, we'll need to check to see if we're already in sync with the
// latest state of the UTXO set.
bestHash, bestHeight, err := r.cfg.Chain.GetBestBlock()
if err != nil {
return err
}
r.bestHeight = uint32(bestHeight)
pruneHash, pruneHeight, err := r.cfg.Graph.PruneTip()
if err != nil {
switch {
// If the graph has never been pruned, or hasn't fully been
// created yet, then we don't treat this as an explicit error.
case err == channeldb.ErrGraphNeverPruned:
case err == channeldb.ErrGraphNotFound:
default:
return err
}
}
log.Infof("Prune tip for Channel Graph: height=%v, hash=%v", pruneHeight,
pruneHash)
switch {
// If the graph has never been pruned, then we can exit early as this
// entails it's being created for the first time and hasn't seen any
// block or created channels.
case pruneHeight == 0 || pruneHash == nil:
return nil
// If the block hashes and heights match exactly, then we don't need to
// prune the channel graph as we're already fully in sync.
case bestHash.IsEqual(pruneHash) && uint32(bestHeight) == pruneHeight:
return nil
}
// If the main chain blockhash at prune height is different from the
// prune hash, this might indicate the database is on a stale branch.
mainBlockHash, err := r.cfg.Chain.GetBlockHash(int64(pruneHeight))
if err != nil {
return err
}
// While we are on a stale branch of the chain, walk backwards to find
// first common block.
for !pruneHash.IsEqual(mainBlockHash) {
log.Infof("channel graph is stale. Disconnecting block %v "+
"(hash=%v)", pruneHeight, pruneHash)
// Prune the graph for every channel that was opened at height
// >= pruneHeight.
_, err := r.cfg.Graph.DisconnectBlockAtHeight(pruneHeight)
if err != nil {
return err
}
pruneHash, pruneHeight, err = r.cfg.Graph.PruneTip()
if err != nil {
switch {
// If at this point the graph has never been pruned, we
// can exit as this entails we are back to the point
// where it hasn't seen any block or created channels,
// alas there's nothing left to prune.
case err == channeldb.ErrGraphNeverPruned:
return nil
case err == channeldb.ErrGraphNotFound:
return nil
default:
return err
}
}
mainBlockHash, err = r.cfg.Chain.GetBlockHash(int64(pruneHeight))
if err != nil {
return err
}
}
log.Infof("Syncing channel graph from height=%v (hash=%v) to height=%v "+
"(hash=%v)", pruneHeight, pruneHash, bestHeight, bestHash)
// If we're not yet caught up, then we'll walk forward in the chain
// pruning the channel graph with each new block that hasn't yet been
// consumed by the channel graph.
var spentOutputs []*wire.OutPoint
for nextHeight := pruneHeight + 1; nextHeight <= uint32(bestHeight); nextHeight++ {
// Break out of the rescan early if a shutdown has been
// requested, otherwise long rescans will block the daemon from
// shutting down promptly.
select {
case <-r.quit:
return ErrRouterShuttingDown
default:
}
// Using the next height, request a manual block pruning from
// the chainview for the particular block hash.
nextHash, err := r.cfg.Chain.GetBlockHash(int64(nextHeight))
if err != nil {
return err
}
filterBlock, err := r.cfg.ChainView.FilterBlock(nextHash)
if err != nil {
return err
}
// We're only interested in all prior outputs that have been
// spent in the block, so collate all the referenced previous
// outpoints within each tx and input.
for _, tx := range filterBlock.Transactions {
for _, txIn := range tx.TxIn {
spentOutputs = append(spentOutputs,
&txIn.PreviousOutPoint)
}
}
}
// With the spent outputs gathered, attempt to prune the channel graph,
// also passing in the best hash+height so the prune tip can be updated.
closedChans, err := r.cfg.Graph.PruneGraph(
spentOutputs, bestHash, uint32(bestHeight),
)
if err != nil {
return err
}
log.Infof("Graph pruning complete: %v channels were closed since "+
"height %v", len(closedChans), pruneHeight)
return nil
}
// pruneZombieChans is a method that will be called periodically to prune out
// any "zombie" channels. We consider channels zombies if *both* edges haven't
// been updated since our zombie horizon. If AssumeChannelValid is present,
// we'll also consider channels zombies if *both* edges are disabled. This
// usually signals that a channel has been closed on-chain. We do this
// periodically to keep a healthy, lively routing table.
func (r *ChannelRouter) pruneZombieChans() error {
chansToPrune := make(map[uint64]struct{})
chanExpiry := r.cfg.ChannelPruneExpiry
log.Infof("Examining channel graph for zombie channels")
// A helper method to detect if the channel belongs to this node
isSelfChannelEdge := func(info *channeldb.ChannelEdgeInfo) bool {
return info.NodeKey1Bytes == r.selfNode.PubKeyBytes ||
info.NodeKey2Bytes == r.selfNode.PubKeyBytes
}
// First, we'll collect all the channels which are eligible for garbage
// collection due to being zombies.
filterPruneChans := func(info *channeldb.ChannelEdgeInfo,
e1, e2 *channeldb.ChannelEdgePolicy) error {
// Exit early in case this channel is already marked to be pruned
if _, markedToPrune := chansToPrune[info.ChannelID]; markedToPrune {
return nil
}
// We'll ensure that we don't attempt to prune our *own*
// channels from the graph, as in any case this should be
// re-advertised by the sub-system above us.
if isSelfChannelEdge(info) {
return nil
}
// If *both* edges haven't been updated for a period of
// chanExpiry, then we'll mark the channel itself as eligible
// for graph pruning.
var e1Zombie, e2Zombie bool
if e1 != nil {
e1Zombie = time.Since(e1.LastUpdate) >= chanExpiry
if e1Zombie {
log.Tracef("Edge #1 of ChannelID(%v) last "+
"update: %v", info.ChannelID,
e1.LastUpdate)
}
}
if e2 != nil {
e2Zombie = time.Since(e2.LastUpdate) >= chanExpiry
if e2Zombie {
log.Tracef("Edge #2 of ChannelID(%v) last "+
"update: %v", info.ChannelID,
e2.LastUpdate)
}
}
// If the channel is not considered zombie, we can move on to
// the next.
if !e1Zombie || !e2Zombie {
return nil
}
log.Debugf("ChannelID(%v) is a zombie, collecting to prune",
info.ChannelID)
// TODO(roasbeef): add ability to delete single directional edge
chansToPrune[info.ChannelID] = struct{}{}
return nil
}
// If AssumeChannelValid is present we'll look at the disabled bit for both
// edges. If they're both disabled, then we can interpret this as the
// channel being closed and can prune it from our graph.
if r.cfg.AssumeChannelValid {
disabledChanIDs, err := r.cfg.Graph.DisabledChannelIDs()
if err != nil {
return fmt.Errorf("unable to get disabled channels ids "+
"chans: %v", err)
}
disabledEdges, err := r.cfg.Graph.FetchChanInfos(disabledChanIDs)
if err != nil {
return fmt.Errorf("unable to fetch disabled channels edges "+
"chans: %v", err)
}
// Ensuring we won't prune our own channel from the graph.
for _, disabledEdge := range disabledEdges {
if !isSelfChannelEdge(disabledEdge.Info) {
chansToPrune[disabledEdge.Info.ChannelID] = struct{}{}
}
}
}
startTime := time.Unix(0, 0)
endTime := time.Now().Add(-1 * chanExpiry)
oldEdges, err := r.cfg.Graph.ChanUpdatesInHorizon(startTime, endTime)
if err != nil {
return fmt.Errorf("unable to fetch expired channel updates "+
"chans: %v", err)
}
for _, u := range oldEdges {
filterPruneChans(u.Info, u.Policy1, u.Policy2)
}
log.Infof("Pruning %v zombie channels", len(chansToPrune))
// With the set of zombie-like channels obtained, we'll do another pass
// to delete them from the channel graph.
toPrune := make([]uint64, 0, len(chansToPrune))
for chanID := range chansToPrune {
toPrune = append(toPrune, chanID)
log.Tracef("Pruning zombie channel with ChannelID(%v)", chanID)
}
if err := r.cfg.Graph.DeleteChannelEdges(toPrune...); err != nil {
return fmt.Errorf("unable to delete zombie channels: %v", err)
}
// With the channels pruned, we'll also attempt to prune any nodes that
// were a part of them.
err = r.cfg.Graph.PruneGraphNodes()
if err != nil && err != channeldb.ErrGraphNodesNotFound {
return fmt.Errorf("unable to prune graph nodes: %v", err)
}
return nil
}
// networkHandler is the primary goroutine for the ChannelRouter. The roles of
// this goroutine include answering queries related to the state of the
// network, pruning the graph on new block notification, applying network
// updates, and registering new topology clients.
//
// NOTE: This MUST be run as a goroutine.
func (r *ChannelRouter) networkHandler() {
defer r.wg.Done()
graphPruneTicker := time.NewTicker(r.cfg.GraphPruneInterval)
defer graphPruneTicker.Stop()
defer r.statTicker.Stop()
r.stats.Reset()
// We'll use this validation barrier to ensure that we process all jobs
// in the proper order during parallel validation.
validationBarrier := NewValidationBarrier(runtime.NumCPU()*4, r.quit)
for {
// If there are stats, resume the statTicker.
if !r.stats.Empty() {
r.statTicker.Resume()
}
select {
// A new fully validated network update has just arrived. As a
// result we'll modify the channel graph accordingly depending
// on the exact type of the message.
case update := <-r.networkUpdates:
// We'll set up any dependants, and wait until a free
// slot for this job opens up, this allow us to not
// have thousands of goroutines active.
validationBarrier.InitJobDependencies(update.msg)
r.wg.Add(1)
go func() {
defer r.wg.Done()
defer validationBarrier.CompleteJob()
// If this message has an existing dependency,
// then we'll wait until that has been fully
// validated before we proceed.
err := validationBarrier.WaitForDependants(
update.msg,
)
if err != nil {
if err != ErrVBarrierShuttingDown {
log.Warnf("unexpected error "+
"during validation "+
"barrier shutdown: %v",
err)
}
return
}
// Process the routing update to determine if
// this is either a new update from our PoV or
// an update to a prior vertex/edge we
// previously accepted.
err = r.processUpdate(update.msg)
update.err <- err
// If this message had any dependencies, then
// we can now signal them to continue.
validationBarrier.SignalDependants(update.msg)
if err != nil {
return
}
// Send off a new notification for the newly
// accepted update.
topChange := &TopologyChange{}
err = addToTopologyChange(
r.cfg.Graph, topChange, update.msg,
)
if err != nil {
log.Errorf("unable to update topology "+
"change notification: %v", err)
return
}
if !topChange.isEmpty() {
r.notifyTopologyChange(topChange)
}
}()
// TODO(roasbeef): remove all unconnected vertexes
// after N blocks pass with no corresponding
// announcements.
case chainUpdate, ok := <-r.staleBlocks:
// If the channel has been closed, then this indicates
// the daemon is shutting down, so we exit ourselves.
if !ok {
return
}
// Since this block is stale, we update our best height
// to the previous block.
blockHeight := uint32(chainUpdate.Height)
atomic.StoreUint32(&r.bestHeight, blockHeight-1)
// Update the channel graph to reflect that this block
// was disconnected.
_, err := r.cfg.Graph.DisconnectBlockAtHeight(blockHeight)
if err != nil {
log.Errorf("unable to prune graph with stale "+
"block: %v", err)
continue
}
// TODO(halseth): notify client about the reorg?
// A new block has arrived, so we can prune the channel graph
// of any channels which were closed in the block.
case chainUpdate, ok := <-r.newBlocks:
// If the channel has been closed, then this indicates
// the daemon is shutting down, so we exit ourselves.
if !ok {
return
}
// We'll ensure that any new blocks received attach
// directly to the end of our main chain. If not, then
// we've somehow missed some blocks. We don't process
// this block as otherwise, we may miss on-chain
// events.
currentHeight := atomic.LoadUint32(&r.bestHeight)
if chainUpdate.Height != currentHeight+1 {
log.Errorf("out of order block: expecting "+
"height=%v, got height=%v", currentHeight+1,
chainUpdate.Height)
continue
}
// Once a new block arrives, we update our running
// track of the height of the chain tip.
blockHeight := uint32(chainUpdate.Height)
atomic.StoreUint32(&r.bestHeight, blockHeight)
log.Infof("Pruning channel graph using block %v (height=%v)",
chainUpdate.Hash, blockHeight)
// We're only interested in all prior outputs that have
// been spent in the block, so collate all the
// referenced previous outpoints within each tx and
// input.
var spentOutputs []*wire.OutPoint
for _, tx := range chainUpdate.Transactions {
for _, txIn := range tx.TxIn {
spentOutputs = append(spentOutputs,
&txIn.PreviousOutPoint)
}
}
// With the spent outputs gathered, attempt to prune
// the channel graph, also passing in the hash+height
// of the block being pruned so the prune tip can be
// updated.
chansClosed, err := r.cfg.Graph.PruneGraph(spentOutputs,
&chainUpdate.Hash, chainUpdate.Height)
if err != nil {
log.Errorf("unable to prune routing table: %v", err)
continue
}
log.Infof("Block %v (height=%v) closed %v channels",
chainUpdate.Hash, blockHeight, len(chansClosed))
if len(chansClosed) == 0 {
continue
}
// Notify all currently registered clients of the newly
// closed channels.
closeSummaries := createCloseSummaries(blockHeight, chansClosed...)
r.notifyTopologyChange(&TopologyChange{
ClosedChannels: closeSummaries,
})
// A new notification client update has arrived. We're either
// gaining a new client, or cancelling notifications for an
// existing client.
case ntfnUpdate := <-r.ntfnClientUpdates:
clientID := ntfnUpdate.clientID
if ntfnUpdate.cancel {
r.RLock()
client, ok := r.topologyClients[ntfnUpdate.clientID]
r.RUnlock()
if ok {
r.Lock()
delete(r.topologyClients, clientID)
r.Unlock()
close(client.exit)
client.wg.Wait()
close(client.ntfnChan)
}
continue
}
r.Lock()
r.topologyClients[ntfnUpdate.clientID] = &topologyClient{
ntfnChan: ntfnUpdate.ntfnChan,
exit: make(chan struct{}),
}
r.Unlock()
// The graph prune ticker has ticked, so we'll examine the
// state of the known graph to filter out any zombie channels
// for pruning.
case <-graphPruneTicker.C:
if err := r.pruneZombieChans(); err != nil {
log.Errorf("Unable to prune zombies: %v", err)
}
// Log any stats if we've processed a non-empty number of
// channels, updates, or nodes. We'll only pause the ticker if
// the last window contained no updates to avoid resuming and
// pausing while consecutive windows contain new info.
case <-r.statTicker.Ticks():
if !r.stats.Empty() {
log.Infof(r.stats.String())
} else {
r.statTicker.Pause()
}
r.stats.Reset()
// The router has been signalled to exit, to we exit our main
// loop so the wait group can be decremented.
case <-r.quit:
return
}
}
}
// assertNodeAnnFreshness returns a non-nil error if we have an announcement in
// the database for the passed node with a timestamp newer than the passed
// timestamp. ErrIgnored will be returned if we already have the node, and
// ErrOutdated will be returned if we have a timestamp that's after the new
// timestamp.
func (r *ChannelRouter) assertNodeAnnFreshness(node route.Vertex,
msgTimestamp time.Time) error {
// If we are not already aware of this node, it means that we don't
// know about any channel using this node. To avoid a DoS attack by
// node announcements, we will ignore such nodes. If we do know about
// this node, check that this update brings info newer than what we
// already have.
lastUpdate, exists, err := r.cfg.Graph.HasLightningNode(node)
if err != nil {
return errors.Errorf("unable to query for the "+
"existence of node: %v", err)
}
if !exists {
return newErrf(ErrIgnored, "Ignoring node announcement"+
" for node not found in channel graph (%x)",
node[:])
}
// If we've reached this point then we're aware of the vertex being
// advertised. So we now check if the new message has a new time stamp,
// if not then we won't accept the new data as it would override newer
// data.
if !lastUpdate.Before(msgTimestamp) {
return newErrf(ErrOutdated, "Ignoring outdated "+
"announcement for %x", node[:])
}
return nil
}
// processUpdate processes a new relate authenticated channel/edge, node or
// channel/edge update network update. If the update didn't affect the internal
// state of the draft due to either being out of date, invalid, or redundant,
// then error is returned.
func (r *ChannelRouter) processUpdate(msg interface{}) error {
switch msg := msg.(type) {
case *channeldb.LightningNode:
// Before we add the node to the database, we'll check to see
// if the announcement is "fresh" or not. If it isn't, then
// we'll return an error.
err := r.assertNodeAnnFreshness(msg.PubKeyBytes, msg.LastUpdate)
if err != nil {
return err
}
if err := r.cfg.Graph.AddLightningNode(msg); err != nil {
return errors.Errorf("unable to add node %v to the "+
"graph: %v", msg.PubKeyBytes, err)
}
log.Tracef("Updated vertex data for node=%x", msg.PubKeyBytes)
r.stats.incNumNodeUpdates()
case *channeldb.ChannelEdgeInfo:
// Prior to processing the announcement we first check if we
// already know of this channel, if so, then we can exit early.
_, _, exists, isZombie, err := r.cfg.Graph.HasChannelEdge(
msg.ChannelID,
)
if err != nil && err != channeldb.ErrGraphNoEdgesFound {
return errors.Errorf("unable to check for edge "+
"existence: %v", err)
}
if isZombie {
return newErrf(ErrIgnored, "ignoring msg for zombie "+
"chan_id=%v", msg.ChannelID)
}
if exists {
return newErrf(ErrIgnored, "ignoring msg for known "+
"chan_id=%v", msg.ChannelID)
}
// If AssumeChannelValid is present, then we are unable to
// perform any of the expensive checks below, so we'll
// short-circuit our path straight to adding the edge to our
// graph.
if r.cfg.AssumeChannelValid {
if err := r.cfg.Graph.AddChannelEdge(msg); err != nil {
return fmt.Errorf("unable to add edge: %v", err)
}
log.Tracef("New channel discovered! Link "+
"connects %x and %x with ChannelID(%v)",
msg.NodeKey1Bytes, msg.NodeKey2Bytes,
msg.ChannelID)
r.stats.incNumEdgesDiscovered()
break
}
// Before we can add the channel to the channel graph, we need
// to obtain the full funding outpoint that's encoded within
// the channel ID.
channelID := lnwire.NewShortChanIDFromInt(msg.ChannelID)
fundingTx, err := r.fetchFundingTx(&channelID)
if err != nil {
return errors.Errorf("unable to fetch funding tx for "+
"chan_id=%v: %v", msg.ChannelID, err)
}
// Recreate witness output to be sure that declared in channel
// edge bitcoin keys and channel value corresponds to the
// reality.
witnessScript, err := input.GenMultiSigScript(
msg.BitcoinKey1Bytes[:], msg.BitcoinKey2Bytes[:],
)
if err != nil {
return err
}
pkScript, err := input.WitnessScriptHash(witnessScript)
if err != nil {
return err
}
// Next we'll validate that this channel is actually well
// formed. If this check fails, then this channel either
// doesn't exist, or isn't the one that was meant to be created
// according to the passed channel proofs.
fundingPoint, err := chanvalidate.Validate(&chanvalidate.Context{
Locator: &chanvalidate.ShortChanIDChanLocator{
ID: channelID,
},
MultiSigPkScript: pkScript,
FundingTx: fundingTx,
})
if err != nil {
return err
}
// Now that we have the funding outpoint of the channel, ensure
// that it hasn't yet been spent. If so, then this channel has
// been closed so we'll ignore it.
fundingPkScript, err := input.WitnessScriptHash(witnessScript)
if err != nil {
return err
}
chanUtxo, err := r.cfg.Chain.GetUtxo(
fundingPoint, fundingPkScript, channelID.BlockHeight,
r.quit,
)
if err != nil {
return fmt.Errorf("unable to fetch utxo "+
"for chan_id=%v, chan_point=%v: %v",
msg.ChannelID, fundingPoint, err)
}
// TODO(roasbeef): this is a hack, needs to be removed
// after commitment fees are dynamic.
msg.Capacity = btcutil.Amount(chanUtxo.Value)
msg.ChannelPoint = *fundingPoint
if err := r.cfg.Graph.AddChannelEdge(msg); err != nil {
return errors.Errorf("unable to add edge: %v", err)
}
log.Tracef("New channel discovered! Link "+
"connects %x and %x with ChannelPoint(%v): "+
"chan_id=%v, capacity=%v",
msg.NodeKey1Bytes, msg.NodeKey2Bytes,
fundingPoint, msg.ChannelID, msg.Capacity)
r.stats.incNumEdgesDiscovered()
// As a new edge has been added to the channel graph, we'll
// update the current UTXO filter within our active
// FilteredChainView so we are notified if/when this channel is
// closed.
filterUpdate := []channeldb.EdgePoint{
{
FundingPkScript: fundingPkScript,
OutPoint: *fundingPoint,
},
}
err = r.cfg.ChainView.UpdateFilter(
filterUpdate, atomic.LoadUint32(&r.bestHeight),
)
if err != nil {
return errors.Errorf("unable to update chain "+
"view: %v", err)
}
case *channeldb.ChannelEdgePolicy:
// We make sure to hold the mutex for this channel ID,
// such that no other goroutine is concurrently doing
// database accesses for the same channel ID.
r.channelEdgeMtx.Lock(msg.ChannelID)
defer r.channelEdgeMtx.Unlock(msg.ChannelID)
edge1Timestamp, edge2Timestamp, exists, isZombie, err :=
r.cfg.Graph.HasChannelEdge(msg.ChannelID)
if err != nil && err != channeldb.ErrGraphNoEdgesFound {
return errors.Errorf("unable to check for edge "+
"existence: %v", err)
}
// If the channel is marked as a zombie in our database, and
// we consider this a stale update, then we should not apply the
// policy.
isStaleUpdate := time.Since(msg.LastUpdate) > r.cfg.ChannelPruneExpiry
if isZombie && isStaleUpdate {
return newErrf(ErrIgnored, "ignoring stale update "+
"(flags=%v|%v) for zombie chan_id=%v",
msg.MessageFlags, msg.ChannelFlags,
msg.ChannelID)
}
// If the channel doesn't exist in our database, we cannot
// apply the updated policy.
if !exists {
return newErrf(ErrIgnored, "ignoring update "+
"(flags=%v|%v) for unknown chan_id=%v",
msg.MessageFlags, msg.ChannelFlags,
msg.ChannelID)
}
// As edges are directional edge node has a unique policy for
// the direction of the edge they control. Therefore we first
// check if we already have the most up to date information for
// that edge. If this message has a timestamp not strictly
// newer than what we already know of we can exit early.
switch {
// A flag set of 0 indicates this is an announcement for the
// "first" node in the channel.
case msg.ChannelFlags&lnwire.ChanUpdateDirection == 0:
// Ignore outdated message.
if !edge1Timestamp.Before(msg.LastUpdate) {
return newErrf(ErrOutdated, "Ignoring "+
"outdated update (flags=%v|%v) for "+
"known chan_id=%v", msg.MessageFlags,
msg.ChannelFlags, msg.ChannelID)
}
// Similarly, a flag set of 1 indicates this is an announcement
// for the "second" node in the channel.
case msg.ChannelFlags&lnwire.ChanUpdateDirection == 1:
// Ignore outdated message.
if !edge2Timestamp.Before(msg.LastUpdate) {
return newErrf(ErrOutdated, "Ignoring "+
"outdated update (flags=%v|%v) for "+
"known chan_id=%v", msg.MessageFlags,
msg.ChannelFlags, msg.ChannelID)
}
}
// Now that we know this isn't a stale update, we'll apply the
// new edge policy to the proper directional edge within the
// channel graph.
if err = r.cfg.Graph.UpdateEdgePolicy(msg); err != nil {
err := errors.Errorf("unable to add channel: %v", err)
log.Error(err)
return err
}
log.Tracef("New channel update applied: %v",
newLogClosure(func() string { return spew.Sdump(msg) }))
r.stats.incNumChannelUpdates()
default:
return errors.Errorf("wrong routing update message type")
}
return nil
}
// fetchFundingTx returns the funding transaction identified by the passed
// short channel ID.
//
// TODO(roasbeef): replace with call to GetBlockTransaction? (would allow to
// later use getblocktxn)
func (r *ChannelRouter) fetchFundingTx(
chanID *lnwire.ShortChannelID) (*wire.MsgTx, error) {
// First fetch the block hash by the block number encoded, then use
// that hash to fetch the block itself.
blockNum := int64(chanID.BlockHeight)
blockHash, err := r.cfg.Chain.GetBlockHash(blockNum)
if err != nil {
return nil, err
}
fundingBlock, err := r.cfg.Chain.GetBlock(blockHash)
if err != nil {
return nil, err
}
// As a sanity check, ensure that the advertised transaction index is
// within the bounds of the total number of transactions within a
// block.
numTxns := uint32(len(fundingBlock.Transactions))
if chanID.TxIndex > numTxns-1 {
return nil, fmt.Errorf("tx_index=#%v is out of range "+
"(max_index=%v), network_chan_id=%v", chanID.TxIndex,
numTxns-1, chanID)
}
return fundingBlock.Transactions[chanID.TxIndex], nil
}
// routingMsg couples a routing related routing topology update to the
// error channel.
type routingMsg struct {
msg interface{}
err chan error
}
// FindRoute attempts to query the ChannelRouter for the optimum path to a
// particular target destination to which it is able to send `amt` after
// factoring in channel capacities and cumulative fees along the route.
func (r *ChannelRouter) FindRoute(source, target route.Vertex,
amt lnwire.MilliSatoshi, restrictions *RestrictParams,
destCustomRecords record.CustomSet,
routeHints map[route.Vertex][]*channeldb.ChannelEdgePolicy,
finalExpiry uint16) (*route.Route, error) {
log.Debugf("Searching for path to %v, sending %v", target, amt)
// We'll attempt to obtain a set of bandwidth hints that can help us
// eliminate certain routes early on in the path finding process.
bandwidthHints, err := generateBandwidthHints(
r.selfNode, r.cfg.QueryBandwidth,
)
if err != nil {
return nil, err
}
// We'll fetch the current block height so we can properly calculate the
// required HTLC time locks within the route.
_, currentHeight, err := r.cfg.Chain.GetBestBlock()
if err != nil {
return nil, err
}
// Now that we know the destination is reachable within the graph, we'll
// execute our path finding algorithm.
finalHtlcExpiry := currentHeight + int32(finalExpiry)
routingTx, err := newDbRoutingTx(r.cfg.Graph)
if err != nil {
return nil, err
}
defer func() {
err := routingTx.close()
if err != nil {
log.Errorf("Error closing db tx: %v", err)
}
}()
path, err := findPath(
&graphParams{
additionalEdges: routeHints,
bandwidthHints: bandwidthHints,
graph: routingTx,
},
restrictions,
&r.cfg.PathFindingConfig,
source, target, amt, finalHtlcExpiry,
)
if err != nil {
return nil, err
}
// Create the route with absolute time lock values.
route, err := newRoute(
source, path, uint32(currentHeight),
finalHopParams{
amt: amt,
totalAmt: amt,
cltvDelta: finalExpiry,
records: destCustomRecords,
},
)
if err != nil {
return nil, err
}
go log.Tracef("Obtained path to send %v to %x: %v",
amt, target, newLogClosure(func() string {
return spew.Sdump(route)
}),
)
return route, nil
}
// generateNewSessionKey generates a new ephemeral private key to be used for a
// payment attempt.
func generateNewSessionKey() (*btcec.PrivateKey, error) {
// Generate a new random session key to ensure that we don't trigger
// any replay.
//
// TODO(roasbeef): add more sources of randomness?
return btcec.NewPrivateKey(btcec.S256())
}
// generateSphinxPacket generates then encodes a sphinx packet which encodes
// the onion route specified by the passed layer 3 route. The blob returned
// from this function can immediately be included within an HTLC add packet to
// be sent to the first hop within the route.
func generateSphinxPacket(rt *route.Route, paymentHash []byte,
sessionKey *btcec.PrivateKey) ([]byte, *sphinx.Circuit, error) {
// Now that we know we have an actual route, we'll map the route into a
// sphinx payument path which includes per-hop paylods for each hop
// that give each node within the route the necessary information
// (fees, CLTV value, etc) to properly forward the payment.
sphinxPath, err := rt.ToSphinxPath()
if err != nil {
return nil, nil, err
}
log.Tracef("Constructed per-hop payloads for payment_hash=%x: %v",
paymentHash[:], newLogClosure(func() string {
path := make([]sphinx.OnionHop, sphinxPath.TrueRouteLength())
for i := range path {
hopCopy := sphinxPath[i]
hopCopy.NodePub.Curve = nil
path[i] = hopCopy
}
return spew.Sdump(path)
}),
)
// Next generate the onion routing packet which allows us to perform
// privacy preserving source routing across the network.
sphinxPacket, err := sphinx.NewOnionPacket(
sphinxPath, sessionKey, paymentHash,
sphinx.DeterministicPacketFiller,
)
if err != nil {
return nil, nil, err
}
// Finally, encode Sphinx packet using its wire representation to be
// included within the HTLC add packet.
var onionBlob bytes.Buffer
if err := sphinxPacket.Encode(&onionBlob); err != nil {
return nil, nil, err
}
log.Tracef("Generated sphinx packet: %v",
newLogClosure(func() string {
// We make a copy of the ephemeral key and unset the
// internal curve here in order to keep the logs from
// getting noisy.
key := *sphinxPacket.EphemeralKey
key.Curve = nil
packetCopy := *sphinxPacket
packetCopy.EphemeralKey = &key
return spew.Sdump(packetCopy)
}),
)
return onionBlob.Bytes(), &sphinx.Circuit{
SessionKey: sessionKey,
PaymentPath: sphinxPath.NodeKeys(),
}, nil
}
// LightningPayment describes a payment to be sent through the network to the
// final destination.
type LightningPayment struct {
// Target is the node in which the payment should be routed towards.
Target route.Vertex
// Amount is the value of the payment to send through the network in
// milli-satoshis.
Amount lnwire.MilliSatoshi
// FeeLimit is the maximum fee in millisatoshis that the payment should
// accept when sending it through the network. The payment will fail
// if there isn't a route with lower fees than this limit.
FeeLimit lnwire.MilliSatoshi
// CltvLimit is the maximum time lock that is allowed for attempts to
// complete this payment.
CltvLimit uint32
// PaymentHash is the r-hash value to use within the HTLC extended to
// the first hop.
PaymentHash [32]byte
// FinalCLTVDelta is the CTLV expiry delta to use for the _final_ hop
// in the route. This means that the final hop will have a CLTV delta
// of at least: currentHeight + FinalCLTVDelta.
FinalCLTVDelta uint16
// PayAttemptTimeout is a timeout value that we'll use to determine
// when we should should abandon the payment attempt after consecutive
// payment failure. This prevents us from attempting to send a payment
// indefinitely. A zero value means the payment will never time out.
//
// TODO(halseth): make wallclock time to allow resume after startup.
PayAttemptTimeout time.Duration
// RouteHints represents the different routing hints that can be used to
// assist a payment in reaching its destination successfully. These
// hints will act as intermediate hops along the route.
//
// NOTE: This is optional unless required by the payment. When providing
// multiple routes, ensure the hop hints within each route are chained
// together and sorted in forward order in order to reach the
// destination successfully.
RouteHints [][]zpay32.HopHint
// OutgoingChannelID is the channel that needs to be taken to the first
// hop. If nil, any channel may be used.
OutgoingChannelID *uint64
// LastHop is the pubkey of the last node before the final destination
// is reached. If nil, any node may be used.
LastHop *route.Vertex
// DestFeatures specifies the set of features we assume the final node
// has for pathfinding. Typically these will be taken directly from an
// invoice, but they can also be manually supplied or assumed by the
// sender. If a nil feature vector is provided, the router will try to
// fallback to the graph in order to load a feature vector for a node in
// the public graph.
DestFeatures *lnwire.FeatureVector
// PaymentAddr is the payment address specified by the receiver. This
// field should be a random 32-byte nonce presented in the receiver's
// invoice to prevent probing of the destination.
PaymentAddr *[32]byte
// PaymentRequest is an optional payment request that this payment is
// attempting to complete.
PaymentRequest []byte
// DestCustomRecords are TLV records that are to be sent to the final
// hop in the new onion payload format. If the destination does not
// understand this new onion payload format, then the payment will
// fail.
DestCustomRecords record.CustomSet
// MaxParts is the maximum number of partial payments that may be used
// to complete the full amount.
MaxParts uint32
}
// SendPayment attempts to send a payment as described within the passed
// LightningPayment. This function is blocking and will return either: when the
// payment is successful, or all candidates routes have been attempted and
// resulted in a failed payment. If the payment succeeds, then a non-nil Route
// will be returned which describes the path the successful payment traversed
// within the network to reach the destination. Additionally, the payment
// preimage will also be returned.
func (r *ChannelRouter) SendPayment(payment *LightningPayment) ([32]byte,
*route.Route, error) {
paySession, err := r.preparePayment(payment)
if err != nil {
return [32]byte{}, nil, err
}
log.Tracef("Dispatching SendPayment for lightning payment: %v",
spewPayment(payment))
// Since this is the first time this payment is being made, we pass nil
// for the existing attempt.
return r.sendPayment(
payment.Amount, payment.FeeLimit, payment.PaymentHash,
payment.PayAttemptTimeout, paySession,
)
}
// SendPaymentAsync is the non-blocking version of SendPayment. The payment
// result needs to be retrieved via the control tower.
func (r *ChannelRouter) SendPaymentAsync(payment *LightningPayment) error {
paySession, err := r.preparePayment(payment)
if err != nil {
return err
}
// Since this is the first time this payment is being made, we pass nil
// for the existing attempt.
r.wg.Add(1)
go func() {
defer r.wg.Done()
log.Tracef("Dispatching SendPayment for lightning payment: %v",
spewPayment(payment))
_, _, err := r.sendPayment(
payment.Amount, payment.FeeLimit, payment.PaymentHash,
payment.PayAttemptTimeout, paySession,
)
if err != nil {
log.Errorf("Payment with hash %x failed: %v",
payment.PaymentHash, err)
}
}()
return nil
}
// spewPayment returns a log closures that provides a spewed string
// representation of the passed payment.
func spewPayment(payment *LightningPayment) logClosure {
return newLogClosure(func() string {
// Make a copy of the payment with a nilled Curve
// before spewing.
var routeHints [][]zpay32.HopHint
for _, routeHint := range payment.RouteHints {
var hopHints []zpay32.HopHint
for _, hopHint := range routeHint {
h := hopHint.Copy()
h.NodeID.Curve = nil
hopHints = append(hopHints, h)
}
routeHints = append(routeHints, hopHints)
}
p := *payment
p.RouteHints = routeHints
return spew.Sdump(p)
})
}
// preparePayment creates the payment session and registers the payment with the
// control tower.
func (r *ChannelRouter) preparePayment(payment *LightningPayment) (
PaymentSession, error) {
// Before starting the HTLC routing attempt, we'll create a fresh
// payment session which will report our errors back to mission
// control.
paySession, err := r.cfg.SessionSource.NewPaymentSession(payment)
if err != nil {
return nil, err
}
// Record this payment hash with the ControlTower, ensuring it is not
// already in-flight.
//
// TODO(roasbeef): store records as part of creation info?
info := &channeldb.PaymentCreationInfo{
PaymentHash: payment.PaymentHash,
Value: payment.Amount,
CreationTime: r.cfg.Clock.Now(),
PaymentRequest: payment.PaymentRequest,
}
err = r.cfg.Control.InitPayment(payment.PaymentHash, info)
if err != nil {
return nil, err
}
return paySession, nil
}
// SendToRoute attempts to send a payment with the given hash through the
// provided route. This function is blocking and will return the obtained
// preimage if the payment is successful or the full error in case of a failure.
func (r *ChannelRouter) SendToRoute(hash lntypes.Hash, rt *route.Route) (
lntypes.Preimage, error) {
// Calculate amount paid to receiver.
amt := rt.ReceiverAmt()
// If this is meant as a MP payment shard, we set the amount
// for the creating info to the total amount of the payment.
finalHop := rt.Hops[len(rt.Hops)-1]
mpp := finalHop.MPP
if mpp != nil {
amt = mpp.TotalMsat()
}
// Record this payment hash with the ControlTower, ensuring it is not
// already in-flight.
info := &channeldb.PaymentCreationInfo{
PaymentHash: hash,
Value: amt,
CreationTime: r.cfg.Clock.Now(),
PaymentRequest: nil,
}
err := r.cfg.Control.InitPayment(hash, info)
switch {
// If this is an MPP attempt and the hash is already registered with
// the database, we can go on to launch the shard.
case err == channeldb.ErrPaymentInFlight && mpp != nil:
// Any other error is not tolerated.
case err != nil:
return [32]byte{}, err
}
log.Tracef("Dispatching SendToRoute for hash %v: %v",
hash, newLogClosure(func() string {
return spew.Sdump(rt)
}),
)
// Launch a shard along the given route.
sh := &shardHandler{
router: r,
paymentHash: hash,
}
var shardError error
attempt, outcome, err := sh.launchShard(rt)
// 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",
hash, err)
controlErr := r.cfg.Control.Fail(
hash, channeldb.FailureReasonError,
)
if controlErr != nil {
return [32]byte{}, controlErr
}
}
// In any case, don't continue if there is an error.
if err != nil {
return lntypes.Preimage{}, err
}
switch {
// Failed to launch shard.
case outcome.err != nil:
shardError = outcome.err
// Shard successfully launched, wait for the result to be available.
default:
result, err := sh.collectResult(attempt)
if err != nil {
return lntypes.Preimage{}, err
}
// We got a successful result.
if result.err == nil {
return result.preimage, nil
}
// The shard failed, break switch to handle it.
shardError = result.err
}
// Since for SendToRoute we won't retry in case the shard fails, we'll
// mark the payment failed with the control tower immediately. Process
// the error to check if it maps into a terminal error code, if not use
// a generic NO_ROUTE error.
reason := r.processSendError(
attempt.AttemptID, &attempt.Route, shardError,
)
if reason == nil {
r := channeldb.FailureReasonNoRoute
reason = &r
}
err = r.cfg.Control.Fail(hash, *reason)
if err != nil {
return lntypes.Preimage{}, err
}
return lntypes.Preimage{}, shardError
}
// sendPayment attempts to send a payment to the passed payment hash. This
// function is blocking and will return either: when the payment is successful,
// or all candidates routes have been attempted and resulted in a failed
// payment. If the payment succeeds, then a non-nil Route will be returned
// which describes the path the successful payment traversed within the network
// to reach the destination. Additionally, the payment preimage will also be
// returned.
//
// The existing attempt argument should be set to nil if this is a payment that
// haven't had any payment attempt sent to the switch yet. If it has had an
// attempt already, it should be passed such that the result can be retrieved.
//
// This method relies on the ControlTower's internal payment state machine to
// carry out its execution. After restarts it is safe, and assumed, that the
// router will call this method for every payment still in-flight according to
// the ControlTower.
func (r *ChannelRouter) sendPayment(
totalAmt, feeLimit lnwire.MilliSatoshi, paymentHash lntypes.Hash,
timeout time.Duration,
paySession PaymentSession) ([32]byte, *route.Route, error) {
// We'll also fetch the current block height so we can properly
// calculate the required HTLC time locks within the route.
_, currentHeight, err := r.cfg.Chain.GetBestBlock()
if err != nil {
return [32]byte{}, nil, err
}
// Now set up a paymentLifecycle struct with these params, such that we
// can resume the payment from the current state.
p := &paymentLifecycle{
router: r,
totalAmount: totalAmt,
feeLimit: feeLimit,
paymentHash: paymentHash,
paySession: paySession,
currentHeight: currentHeight,
}
// If a timeout is specified, create a timeout channel. If no timeout is
// specified, the channel is left nil and will never abort the payment
// loop.
if timeout != 0 {
p.timeoutChan = time.After(timeout)
}
return p.resumePayment()
}
// tryApplyChannelUpdate tries to apply a channel update present in the failure
// message if any.
func (r *ChannelRouter) tryApplyChannelUpdate(rt *route.Route,
errorSourceIdx int, failure lnwire.FailureMessage) error {
// It makes no sense to apply our own channel updates.
if errorSourceIdx == 0 {
log.Errorf("Channel update of ourselves received")
return nil
}
// Extract channel update if the error contains one.
update := r.extractChannelUpdate(failure)
if update == nil {
return nil
}
// Parse pubkey to allow validation of the channel update. This should
// always succeed, otherwise there is something wrong in our
// implementation. Therefore return an error.
errVertex := rt.Hops[errorSourceIdx-1].PubKeyBytes
errSource, err := btcec.ParsePubKey(
errVertex[:], btcec.S256(),
)
if err != nil {
log.Errorf("Cannot parse pubkey: idx=%v, pubkey=%v",
errorSourceIdx, errVertex)
return err
}
// Apply channel update.
if !r.applyChannelUpdate(update, errSource) {
log.Debugf("Invalid channel update received: node=%v",
errVertex)
}
return nil
}
// processSendError analyzes the error for the payment attempt received from the
// switch and updates mission control and/or channel policies. Depending on the
// error type, this error is either the final outcome of the payment or we need
// to continue with an alternative route. This is indicated by the boolean
// return value.
func (r *ChannelRouter) processSendError(paymentID uint64, rt *route.Route,
sendErr error) *channeldb.FailureReason {
internalErrorReason := channeldb.FailureReasonError
reportFail := func(srcIdx *int,
msg lnwire.FailureMessage) *channeldb.FailureReason {
// Report outcome to mission control.
reason, err := r.cfg.MissionControl.ReportPaymentFail(
paymentID, rt, srcIdx, msg,
)
if err != nil {
log.Errorf("Error reporting payment result to mc: %v",
err)
return &internalErrorReason
}
return reason
}
if sendErr == htlcswitch.ErrUnreadableFailureMessage {
log.Tracef("Unreadable failure when sending htlc")
return reportFail(nil, nil)
}
// If the error is a ClearTextError, we have received a valid wire
// failure message, either from our own outgoing link or from a node
// down the route. If the error is not related to the propagation of
// our payment, we can stop trying because an internal error has
// occurred.
rtErr, ok := sendErr.(htlcswitch.ClearTextError)
if !ok {
return &internalErrorReason
}
// failureSourceIdx is the index of the node that the failure occurred
// at. If the ClearTextError received is not a ForwardingError the
// payment error occurred at our node, so we leave this value as 0
// to indicate that the failure occurred locally. If the error is a
// ForwardingError, it did not originate at our node, so we set
// failureSourceIdx to the index of the node where the failure occurred.
failureSourceIdx := 0
source, ok := rtErr.(*htlcswitch.ForwardingError)
if ok {
failureSourceIdx = source.FailureSourceIdx
}
// Extract the wire failure and apply channel update if it contains one.
// If we received an unknown failure message from a node along the
// route, the failure message will be nil.
failureMessage := rtErr.WireMessage()
if failureMessage != nil {
err := r.tryApplyChannelUpdate(
rt, failureSourceIdx, failureMessage,
)
if err != nil {
return &internalErrorReason
}
}
log.Tracef("Node=%v reported failure when sending htlc",
failureSourceIdx)
return reportFail(&failureSourceIdx, failureMessage)
}
// extractChannelUpdate examines the error and extracts the channel update.
func (r *ChannelRouter) extractChannelUpdate(
failure lnwire.FailureMessage) *lnwire.ChannelUpdate {
var update *lnwire.ChannelUpdate
switch onionErr := failure.(type) {
case *lnwire.FailExpiryTooSoon:
update = &onionErr.Update
case *lnwire.FailAmountBelowMinimum:
update = &onionErr.Update
case *lnwire.FailFeeInsufficient:
update = &onionErr.Update
case *lnwire.FailIncorrectCltvExpiry:
update = &onionErr.Update
case *lnwire.FailChannelDisabled:
update = &onionErr.Update
case *lnwire.FailTemporaryChannelFailure:
update = onionErr.Update
}
return update
}
// applyChannelUpdate validates a channel update and if valid, applies it to the
// database. It returns a bool indicating whether the updates was successful.
func (r *ChannelRouter) applyChannelUpdate(msg *lnwire.ChannelUpdate,
pubKey *btcec.PublicKey) bool {
ch, _, _, err := r.GetChannelByID(msg.ShortChannelID)
if err != nil {
log.Errorf("Unable to retrieve channel by id: %v", err)
return false
}
if err := ValidateChannelUpdateAnn(pubKey, ch.Capacity, msg); err != nil {
log.Errorf("Unable to validate channel update: %v", err)
return false
}
err = r.UpdateEdge(&channeldb.ChannelEdgePolicy{
SigBytes: msg.Signature.ToSignatureBytes(),
ChannelID: msg.ShortChannelID.ToUint64(),
LastUpdate: time.Unix(int64(msg.Timestamp), 0),
MessageFlags: msg.MessageFlags,
ChannelFlags: msg.ChannelFlags,
TimeLockDelta: msg.TimeLockDelta,
MinHTLC: msg.HtlcMinimumMsat,
MaxHTLC: msg.HtlcMaximumMsat,
FeeBaseMSat: lnwire.MilliSatoshi(msg.BaseFee),
FeeProportionalMillionths: lnwire.MilliSatoshi(msg.FeeRate),
})
if err != nil && !IsError(err, ErrIgnored, ErrOutdated) {
log.Errorf("Unable to apply channel update: %v", err)
return false
}
return true
}
// AddNode is used to add information about a node to the router database. If
// the node with this pubkey is not present in an existing channel, it will
// be ignored.
//
// NOTE: This method is part of the ChannelGraphSource interface.
func (r *ChannelRouter) AddNode(node *channeldb.LightningNode) error {
rMsg := &routingMsg{
msg: node,
err: make(chan error, 1),
}
select {
case r.networkUpdates <- rMsg:
select {
case err := <-rMsg.err:
return err
case <-r.quit:
return ErrRouterShuttingDown
}
case <-r.quit:
return ErrRouterShuttingDown
}
}
// AddEdge is used to add edge/channel to the topology of the router, after all
// information about channel will be gathered this edge/channel might be used
// in construction of payment path.
//
// NOTE: This method is part of the ChannelGraphSource interface.
func (r *ChannelRouter) AddEdge(edge *channeldb.ChannelEdgeInfo) error {
rMsg := &routingMsg{
msg: edge,
err: make(chan error, 1),
}
select {
case r.networkUpdates <- rMsg:
select {
case err := <-rMsg.err:
return err
case <-r.quit:
return ErrRouterShuttingDown
}
case <-r.quit:
return ErrRouterShuttingDown
}
}
// UpdateEdge is used to update edge information, without this message edge
// considered as not fully constructed.
//
// NOTE: This method is part of the ChannelGraphSource interface.
func (r *ChannelRouter) UpdateEdge(update *channeldb.ChannelEdgePolicy) error {
rMsg := &routingMsg{
msg: update,
err: make(chan error, 1),
}
select {
case r.networkUpdates <- rMsg:
select {
case err := <-rMsg.err:
return err
case <-r.quit:
return ErrRouterShuttingDown
}
case <-r.quit:
return ErrRouterShuttingDown
}
}
// CurrentBlockHeight returns the block height from POV of the router subsystem.
//
// NOTE: This method is part of the ChannelGraphSource interface.
func (r *ChannelRouter) CurrentBlockHeight() (uint32, error) {
_, height, err := r.cfg.Chain.GetBestBlock()
return uint32(height), err
}
// GetChannelByID return the channel by the channel id.
//
// NOTE: This method is part of the ChannelGraphSource interface.
func (r *ChannelRouter) GetChannelByID(chanID lnwire.ShortChannelID) (
*channeldb.ChannelEdgeInfo,
*channeldb.ChannelEdgePolicy,
*channeldb.ChannelEdgePolicy, error) {
return r.cfg.Graph.FetchChannelEdgesByID(chanID.ToUint64())
}
// FetchLightningNode attempts to look up a target node by its identity public
// key. channeldb.ErrGraphNodeNotFound is returned if the node doesn't exist
// within the graph.
//
// NOTE: This method is part of the ChannelGraphSource interface.
func (r *ChannelRouter) FetchLightningNode(node route.Vertex) (*channeldb.LightningNode, error) {
return r.cfg.Graph.FetchLightningNode(nil, node)
}
// ForEachNode is used to iterate over every node in router topology.
//
// NOTE: This method is part of the ChannelGraphSource interface.
func (r *ChannelRouter) ForEachNode(cb func(*channeldb.LightningNode) error) error {
return r.cfg.Graph.ForEachNode(nil, func(_ kvdb.ReadTx, n *channeldb.LightningNode) error {
return cb(n)
})
}
// ForAllOutgoingChannels is used to iterate over all outgoing channels owned by
// the router.
//
// NOTE: This method is part of the ChannelGraphSource interface.
func (r *ChannelRouter) ForAllOutgoingChannels(cb func(*channeldb.ChannelEdgeInfo,
*channeldb.ChannelEdgePolicy) error) error {
return r.selfNode.ForEachChannel(nil, func(_ kvdb.ReadTx, c *channeldb.ChannelEdgeInfo,
e, _ *channeldb.ChannelEdgePolicy) error {
if e == nil {
return fmt.Errorf("Channel from self node has no policy")
}
return cb(c, e)
})
}
// ForEachChannel is used to iterate over every known edge (channel) within our
// view of the channel graph.
//
// NOTE: This method is part of the ChannelGraphSource interface.
func (r *ChannelRouter) ForEachChannel(cb func(chanInfo *channeldb.ChannelEdgeInfo,
e1, e2 *channeldb.ChannelEdgePolicy) error) error {
return r.cfg.Graph.ForEachChannel(cb)
}
// AddProof updates the channel edge info with proof which is needed to
// properly announce the edge to the rest of the network.
//
// NOTE: This method is part of the ChannelGraphSource interface.
func (r *ChannelRouter) AddProof(chanID lnwire.ShortChannelID,
proof *channeldb.ChannelAuthProof) error {
info, _, _, err := r.cfg.Graph.FetchChannelEdgesByID(chanID.ToUint64())
if err != nil {
return err
}
info.AuthProof = proof
return r.cfg.Graph.UpdateChannelEdge(info)
}
// IsStaleNode returns true if the graph source has a node announcement for the
// target node with a more recent timestamp.
//
// NOTE: This method is part of the ChannelGraphSource interface.
func (r *ChannelRouter) IsStaleNode(node route.Vertex, timestamp time.Time) bool {
// If our attempt to assert that the node announcement is fresh fails,
// then we know that this is actually a stale announcement.
return r.assertNodeAnnFreshness(node, timestamp) != nil
}
// IsPublicNode determines whether the given vertex is seen as a public node in
// the graph from the graph's source node's point of view.
//
// NOTE: This method is part of the ChannelGraphSource interface.
func (r *ChannelRouter) IsPublicNode(node route.Vertex) (bool, error) {
return r.cfg.Graph.IsPublicNode(node)
}
// IsKnownEdge returns true if the graph source already knows of the passed
// channel ID either as a live or zombie edge.
//
// NOTE: This method is part of the ChannelGraphSource interface.
func (r *ChannelRouter) IsKnownEdge(chanID lnwire.ShortChannelID) bool {
_, _, exists, isZombie, _ := r.cfg.Graph.HasChannelEdge(chanID.ToUint64())
return exists || isZombie
}
// IsStaleEdgePolicy returns true if the graph soruce has a channel edge for
// the passed channel ID (and flags) that have a more recent timestamp.
//
// NOTE: This method is part of the ChannelGraphSource interface.
func (r *ChannelRouter) IsStaleEdgePolicy(chanID lnwire.ShortChannelID,
timestamp time.Time, flags lnwire.ChanUpdateChanFlags) bool {
edge1Timestamp, edge2Timestamp, exists, isZombie, err :=
r.cfg.Graph.HasChannelEdge(chanID.ToUint64())
if err != nil {
return false
}
// If we know of the edge as a zombie, then we'll make some additional
// checks to determine if the new policy is fresh.
if isZombie {
// When running with AssumeChannelValid, we also prune channels
// if both of their edges are disabled. We'll mark the new
// policy as stale if it remains disabled.
if r.cfg.AssumeChannelValid {
isDisabled := flags&lnwire.ChanUpdateDisabled ==
lnwire.ChanUpdateDisabled
if isDisabled {
return true
}
}
// Otherwise, we'll fall back to our usual ChannelPruneExpiry.
return time.Since(timestamp) > r.cfg.ChannelPruneExpiry
}
// If we don't know of the edge, then it means it's fresh (thus not
// stale).
if !exists {
return false
}
// As edges are directional edge node has a unique policy for the
// direction of the edge they control. Therefore we first check if we
// already have the most up to date information for that edge. If so,
// then we can exit early.
switch {
// A flag set of 0 indicates this is an announcement for the "first"
// node in the channel.
case flags&lnwire.ChanUpdateDirection == 0:
return !edge1Timestamp.Before(timestamp)
// Similarly, a flag set of 1 indicates this is an announcement for the
// "second" node in the channel.
case flags&lnwire.ChanUpdateDirection == 1:
return !edge2Timestamp.Before(timestamp)
}
return false
}
// MarkEdgeLive clears an edge from our zombie index, deeming it as live.
//
// NOTE: This method is part of the ChannelGraphSource interface.
func (r *ChannelRouter) MarkEdgeLive(chanID lnwire.ShortChannelID) error {
return r.cfg.Graph.MarkEdgeLive(chanID.ToUint64())
}
// generateBandwidthHints is a helper function that's utilized the main
// findPath function in order to obtain hints from the lower layer w.r.t to the
// available bandwidth of edges on the network. Currently, we'll only obtain
// bandwidth hints for the edges we directly have open ourselves. Obtaining
// these hints allows us to reduce the number of extraneous attempts as we can
// skip channels that are inactive, or just don't have enough bandwidth to
// carry the payment.
func generateBandwidthHints(sourceNode *channeldb.LightningNode,
queryBandwidth func(*channeldb.ChannelEdgeInfo) lnwire.MilliSatoshi) (map[uint64]lnwire.MilliSatoshi, error) {
// First, we'll collect the set of outbound edges from the target
// source node.
var localChans []*channeldb.ChannelEdgeInfo
err := sourceNode.ForEachChannel(nil, func(tx kvdb.ReadTx,
edgeInfo *channeldb.ChannelEdgeInfo,
_, _ *channeldb.ChannelEdgePolicy) error {
localChans = append(localChans, edgeInfo)
return nil
})
if err != nil {
return nil, err
}
// Now that we have all of our outbound edges, we'll populate the set
// of bandwidth hints, querying the lower switch layer for the most up
// to date values.
bandwidthHints := make(map[uint64]lnwire.MilliSatoshi)
for _, localChan := range localChans {
bandwidthHints[localChan.ChannelID] = queryBandwidth(localChan)
}
return bandwidthHints, nil
}
// ErrNoChannel is returned when a route cannot be built because there are no
// channels that satisfy all requirements.
type ErrNoChannel struct {
position int
fromNode route.Vertex
}
// Error returns a human readable string describing the error.
func (e ErrNoChannel) Error() string {
return fmt.Sprintf("no matching outgoing channel available for "+
"node %v (%v)", e.position, e.fromNode)
}
// BuildRoute returns a fully specified route based on a list of pubkeys. If
// amount is nil, the minimum routable amount is used. To force a specific
// outgoing channel, use the outgoingChan parameter.
func (r *ChannelRouter) BuildRoute(amt *lnwire.MilliSatoshi,
hops []route.Vertex, outgoingChan *uint64,
finalCltvDelta int32) (*route.Route, error) {
log.Tracef("BuildRoute called: hopsCount=%v, amt=%v",
len(hops), amt)
// If no amount is specified, we need to build a route for the minimum
// amount that this route can carry.
useMinAmt := amt == nil
// We'll attempt to obtain a set of bandwidth hints that helps us select
// the best outgoing channel to use in case no outgoing channel is set.
bandwidthHints, err := generateBandwidthHints(
r.selfNode, r.cfg.QueryBandwidth,
)
if err != nil {
return nil, err
}
// Fetch the current block height outside the routing transaction, to
// prevent the rpc call blocking the database.
_, height, err := r.cfg.Chain.GetBestBlock()
if err != nil {
return nil, err
}
// Allocate a list that will contain the unified policies for this
// route.
edges := make([]*unifiedPolicy, len(hops))
var runningAmt lnwire.MilliSatoshi
if useMinAmt {
// For minimum amount routes, aim to deliver at least 1 msat to
// the destination. There are nodes in the wild that have a
// min_htlc channel policy of zero, which could lead to a zero
// amount payment being made.
runningAmt = 1
} else {
// If an amount is specified, we need to build a route that
// delivers exactly this amount to the final destination.
runningAmt = *amt
}
// Open a transaction to execute the graph queries in.
routingTx, err := newDbRoutingTx(r.cfg.Graph)
if err != nil {
return nil, err
}
defer func() {
err := routingTx.close()
if err != nil {
log.Errorf("Error closing db tx: %v", err)
}
}()
// Traverse hops backwards to accumulate fees in the running amounts.
source := r.selfNode.PubKeyBytes
for i := len(hops) - 1; i >= 0; i-- {
toNode := hops[i]
var fromNode route.Vertex
if i == 0 {
fromNode = source
} else {
fromNode = hops[i-1]
}
localChan := i == 0
// Build unified policies for this hop based on the channels
// known in the graph.
u := newUnifiedPolicies(source, toNode, outgoingChan)
err := u.addGraphPolicies(routingTx)
if err != nil {
return nil, err
}
// Exit if there are no channels.
unifiedPolicy, ok := u.policies[fromNode]
if !ok {
return nil, ErrNoChannel{
fromNode: fromNode,
position: i,
}
}
// If using min amt, increase amt if needed.
if useMinAmt {
min := unifiedPolicy.minAmt()
if min > runningAmt {
runningAmt = min
}
}
// Get a forwarding policy for the specific amount that we want
// to forward.
policy := unifiedPolicy.getPolicy(runningAmt, bandwidthHints)
if policy == nil {
return nil, ErrNoChannel{
fromNode: fromNode,
position: i,
}
}
// Add fee for this hop.
if !localChan {
runningAmt += policy.ComputeFee(runningAmt)
}
log.Tracef("Select channel %v at position %v", policy.ChannelID, i)
edges[i] = unifiedPolicy
}
// Now that we arrived at the start of the route and found out the route
// total amount, we make a forward pass. Because the amount may have
// been increased in the backward pass, fees need to be recalculated and
// amount ranges re-checked.
var pathEdges []*channeldb.ChannelEdgePolicy
receiverAmt := runningAmt
for i, edge := range edges {
policy := edge.getPolicy(receiverAmt, bandwidthHints)
if policy == nil {
return nil, ErrNoChannel{
fromNode: hops[i-1],
position: i,
}
}
if i > 0 {
// Decrease the amount to send while going forward.
receiverAmt -= policy.ComputeFeeFromIncoming(
receiverAmt,
)
}
pathEdges = append(pathEdges, policy)
}
// Build and return the final route.
return newRoute(
source, pathEdges, uint32(height),
finalHopParams{
amt: receiverAmt,
totalAmt: receiverAmt,
cltvDelta: uint16(finalCltvDelta),
records: nil,
},
)
}