lnd.xprv/routing/router.go
Olaoluwa Osuntokun cc19695dad
routing: reject channel announcement if connected vertexes are unknown
This commit modifies the processing in the routing package eo new
announcements. Previously,  if we cgot a cnew channel announcement but
didn’t yet know of the verses that the chanell connected, the
cnnounacment would be accepted. This behavior was eronoues as if the
channel were to be queried for, the DB query would fail as we would be
unable to retrieve the two nodes involved int he channel.

To avoid such an error case, we will now _reject_ any channel
announcements in which we don’t yet have a valid node announcement for
the connected nodes. This case has been inserted into the handling of
channel announcement, a new test has been added, and finally older
tests have also been updated to ensure that nodes are added to the
database _before_ the edge is.
2017-05-14 19:27:24 -07:00

1148 lines
38 KiB
Go

package routing
import (
"bytes"
"fmt"
"sort"
"sync"
"sync/atomic"
"github.com/boltdb/bolt"
"github.com/davecgh/go-spew/spew"
"github.com/lightningnetwork/lnd/channeldb"
"github.com/lightningnetwork/lnd/lnwallet"
"github.com/lightningnetwork/lnd/lnwire"
"github.com/lightningnetwork/lnd/routing/chainview"
"github.com/roasbeef/btcd/btcec"
"github.com/roasbeef/btcd/wire"
"github.com/roasbeef/btcutil"
"github.com/go-errors/errors"
"github.com/lightningnetwork/lightning-onion"
)
// ChannelGraphSource represent the source of information about the topology of
// lightning network, it responsible for addition of nodes, edges
// and applying edges updates, return the current block with with out
// topology is synchronized.
type ChannelGraphSource interface {
// AddNode is used to add node to the topology of the router, after
// this node might be used in construction of payment path.
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
// ForAllOutgoingChannels is used to iterate over all channels
// eminating from the "source" node which is the center of the
// star-graph.
ForAllOutgoingChannels(cb func(c *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)
// 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
}
// FeeSchema is the set fee configuration for a Lighting Node on the network.
// Using the coefficients described within he schema, the required fee to
// forward outgoing payments can be derived.
//
// TODO(roasbeef): should be in switch instead?
type FeeSchema struct {
// TODO(rosbeef): all these should be in msat instead
// BaseFee is the base amount that will be chained for ANY payment
// forwarded.
BaseFee btcutil.Amount
// FeeRate is the rate that will be charged for forwarding payments.
// The fee rate has a granularity of 1/1000 th of a mili-satoshi, or a
// millionth of a satoshi.
FeeRate btcutil.Amount
}
// 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
// FeeSchema is the set fee schema that will be announced on to the
// network.
// TODO(roasbeef): should either be in discovery or switch
FeeSchema *FeeSchema
// SendToSwitch 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.
SendToSwitch func(firstHop *btcec.PublicKey,
htlcAdd *lnwire.UpdateAddHTLC) ([32]byte, error)
}
// routeTuple is an entry within the ChannelRouter's route cache. We cache
// prospective routes based on first the destination, and then the target
// amount. We required the target amount as that will influence the available
// set of paths for a payment.
type routeTuple struct {
amt btcutil.Amount
dest [33]byte
}
// newRouteTuple creates a new route tuple from the target and amount.
func newRouteTuple(amt btcutil.Amount, dest *btcec.PublicKey) routeTuple {
r := routeTuple{
amt: amt,
}
copy(r.dest[:], dest.SerializeCompressed())
return r
}
// 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
started uint32
stopped uint32
bestHeight uint32
// 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
// routeCache is a map that caches the k-shortest paths from ourselves
// to a given target destination for a particular payment amount. This
// map is used as an optimization to speed up subsequent payments to a
// particular destination. This map will be cleared each time a new
// channel announcement is accepted, or a new block arrives that
// results in channels being closed.
//
// TODO(roasbeef): make LRU
routeCacheMtx sync.RWMutex
routeCache map[routeTuple][]*Route
// newBlocks is a channel in which new blocks connected to the end of
// the main chain are sent over.
newBlocks <-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
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
}
return &ChannelRouter{
cfg: &cfg,
selfNode: selfNode,
networkUpdates: make(chan *routingMsg),
topologyClients: make(map[uint64]topologyClient),
ntfnClientUpdates: make(chan *topologyClientUpdate),
routeCache: make(map[routeTuple][]*Route),
quit: make(chan struct{}),
}, 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")
// First, we'll start the chain view instance (if it isn't already
// started).
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()
// 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
}
// Once we've concluded our manual block pruning, we'll constrcut and
// apply a fresh chain filter to the active FilteredChainView instance.
channelView, err := r.cfg.Graph.ChannelView()
if err != nil && err != channeldb.ErrGraphNoEdgesFound {
return err
}
log.Infof("Filtering chain using %v channels active", len(channelView))
err = r.cfg.ChainView.UpdateFilter(channelView, r.bestHeight)
if err != nil {
return err
}
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.Infof("Channel Router shutting down")
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
}
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 in
// the chain pruning the channel graph with each new block in the chain
// that hasn't yet been consumed by the channel graph.
var numChansClosed uint32
for nextHeight := pruneHeight + 1; nextHeight <= uint32(bestHeight); nextHeight++ {
// 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've been
// spent in the block, so collate all the referenced previous
// outpoints within each tx and input.
var spentOutputs []*wire.OutPoint
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 hash+height of the block
// being pruned so the prune tip can be updated.
closedChans, err := r.cfg.Graph.PruneGraph(spentOutputs, nextHash,
nextHeight)
if err != nil {
return err
}
numClosed := uint32(len(closedChans))
log.Infof("Block %v (height=%v) closed %v channels",
nextHash, nextHeight, numClosed)
numChansClosed += numClosed
}
log.Infof("Graph pruning complete: %v channels we're closed since "+
"height %v", numChansClosed, pruneHeight)
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()
for {
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 updateMsg := <-r.networkUpdates:
// 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(updateMsg.msg)
updateMsg.err <- err
if err != nil {
continue
}
// Send off a new notification for the newly
// accepted update.
topChange := &TopologyChange{}
err = addToTopologyChange(r.cfg.Graph, topChange,
updateMsg.msg)
if err != nil {
log.Errorf("unable to update topology "+
"change notification: %v", err)
continue
}
if !topChange.isEmpty() {
r.notifyTopologyChange(topChange)
}
// TODO(roasbeef): remove all unconnected vertexes
// after N blocks pass with no corresponding
// announcements.
// 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
}
// Once a new block arrives, we update our running
// track of the height of the chain tip.
blockHeight := uint32(chainUpdate.Height)
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've
// 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
}
// Invalidate the route cache as channels within the
// graph have closed, which may affect our choice of
// the KSP's for a particular routeTuple.
r.routeCacheMtx.Lock()
r.routeCache = make(map[routeTuple][]*Route)
r.routeCacheMtx.Unlock()
// 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 {
if client, ok := r.topologyClients[ntfnUpdate.clientID]; ok {
delete(r.topologyClients, clientID)
close(client.ntfnChan)
close(client.exit)
}
continue
}
r.topologyClients[ntfnUpdate.clientID] = topologyClient{
ntfnChan: ntfnUpdate.ntfnChan,
exit: make(chan struct{}),
}
// The router has been signalled to exit, to we exit our main
// loop so the wait group can be decremented.
case <-r.quit:
return
}
}
}
// 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 {
var invalidateCache bool
switch msg := msg.(type) {
case *channeldb.LightningNode:
// Before proceeding ensure that we aren't already away of this
// node, and if we are then this is a newer update that we
// known of.
lastUpdate, exists, err := r.cfg.Graph.HasLightningNode(msg.PubKey)
if err != nil {
return errors.Errorf("unable to query for the "+
"existence of node: %v", err)
}
// If we've reached this pint then we're aware of th 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 exists && lastUpdate.After(msg.LastUpdate) ||
lastUpdate.Equal(msg.LastUpdate) {
return newErrf(ErrOutdated, "Ignoring outdated "+
"announcement for %x", msg.PubKey.SerializeCompressed())
}
if err := r.cfg.Graph.AddLightningNode(msg); err != nil {
return errors.Errorf("unable to add node %v to the "+
"graph: %v", msg.PubKey.SerializeCompressed(), err)
}
log.Infof("Updated vertex data for node=%x",
msg.PubKey.SerializeCompressed())
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, err := r.cfg.Graph.HasChannelEdge(msg.ChannelID)
if err != nil && err != channeldb.ErrGraphNoEdgesFound {
return errors.Errorf("unable to check for edge "+
"existence: %v", err)
} else if exists {
return newErrf(ErrIgnored, "Ignoring msg for known "+
"chan_id=%v", msg.ChannelID)
}
// If we don't yet know about this edge, then we'll do an
// additional check to ensure that we have information about
// the two nodes that this edge connects.
_, exists, _ = r.cfg.Graph.HasLightningNode(msg.NodeKey1)
if !exists {
return errors.Errorf("unable to add channel edge, info "+
"for node %x is missing",
msg.NodeKey1.SerializeCompressed())
}
_, exists, _ = r.cfg.Graph.HasLightningNode(msg.NodeKey2)
if !exists {
return errors.Errorf("unable to add channel edge, info "+
"for node %x is missing",
msg.NodeKey1.SerializeCompressed())
}
// 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)
fundingPoint, err := r.fetchChanPoint(&channelID)
if err != nil {
return errors.Errorf("unable to fetch chan point for "+
"chan_id=%v: %v", msg.ChannelID, 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.
chanUtxo, err := r.cfg.Chain.GetUtxo(fundingPoint,
channelID.BlockHeight)
if err != nil {
return errors.Errorf("unable to fetch utxo 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.
_, witnessOutput, err := lnwallet.GenFundingPkScript(
msg.BitcoinKey1.SerializeCompressed(),
msg.BitcoinKey2.SerializeCompressed(),
chanUtxo.Value,
)
if err != nil {
return errors.Errorf("unable to create funding pk "+
"script: %v", err)
}
// By checking the equality of witness pkscripts we checks that
// funding witness script is multisignature lock which contains
// both local and remote public keys which was declared in
// channel edge and also that the announced channel value is
// right.
if !bytes.Equal(witnessOutput.PkScript, chanUtxo.PkScript) {
return errors.Errorf("pkScript mismatch: expected %v, "+
"got %v", witnessOutput.PkScript, chanUtxo.PkScript)
}
// TODO(roasbeef): this is a hack, needs to be removed
// after commitment fees are dynamic.
msg.Capacity = btcutil.Amount(chanUtxo.Value) - btcutil.Amount(5000)
msg.ChannelPoint = *fundingPoint
if err := r.cfg.Graph.AddChannelEdge(msg); err != nil {
return errors.Errorf("unable to add edge: %v", err)
}
invalidateCache = true
log.Infof("New channel discovered! Link "+
"connects %x and %x with ChannelPoint(%v): "+
"chan_id=%v, capacity=%v",
msg.NodeKey1.SerializeCompressed(),
msg.NodeKey2.SerializeCompressed(),
fundingPoint, msg.ChannelID, msg.Capacity)
// 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 := []wire.OutPoint{*fundingPoint}
err = r.cfg.ChainView.UpdateFilter(filterUpdate, r.bestHeight)
if err != nil {
return errors.Errorf("unable to update chain "+
"view: %v", err)
}
case *channeldb.ChannelEdgePolicy:
channelID := lnwire.NewShortChanIDFromInt(msg.ChannelID)
edge1Timestamp, edge2Timestamp, _, err := r.cfg.Graph.HasChannelEdge(msg.ChannelID)
if err != nil && err != channeldb.ErrGraphNoEdgesFound {
return errors.Errorf("unable to check for edge "+
"existence: %v", err)
}
// 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 msg.Flags {
// A flag set of 0 indicates this is an announcement for the
// "first" node in the channel.
case 0:
if edge1Timestamp.After(msg.LastUpdate) ||
edge1Timestamp.Equal(msg.LastUpdate) {
return newErrf(ErrIgnored, "Ignoring announcement "+
"(flags=%v) for known chan_id=%v", msg.Flags,
msg.ChannelID)
}
// Similarly, a flag set of 1 indicates this is an announcement
// for the "second" node in the channel.
case 1:
if edge2Timestamp.After(msg.LastUpdate) ||
edge2Timestamp.Equal(msg.LastUpdate) {
return newErrf(ErrIgnored, "Ignoring announcement "+
"(flags=%v) for known chan_id=%v", msg.Flags,
msg.ChannelID)
}
}
// Before we can update the channel information, we'll ensure
// that the target channel is still open by querying the
// utxo-set for its existence.
chanPoint, err := r.fetchChanPoint(&channelID)
if err != nil {
return errors.Errorf("unable to fetch chan point for "+
"chan_id=%v: %v", msg.ChannelID, err)
}
_, err = r.cfg.Chain.GetUtxo(chanPoint, channelID.BlockHeight)
if err != nil {
return errors.Errorf("unable to fetch utxo for "+
"chan_id=%v: %v", msg.ChannelID, err)
}
// 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
}
invalidateCache = true
log.Infof("New channel update applied: %v",
spew.Sdump(msg))
default:
return errors.Errorf("wrong routing update message type")
}
// If we've received a channel update, then invalidate the route cache
// as channels within the graph have closed, which may affect our
// choice of the KSP's for a particular routeTuple.
if invalidateCache {
r.routeCacheMtx.Lock()
r.routeCache = make(map[routeTuple][]*Route)
r.routeCacheMtx.Unlock()
}
return nil
}
// fetchChanPoint retrieves the original outpoint which is encoded within the
// channelID.
//
// TODO(roasbeef): replace iwth call to GetBlockTransaction? (woudl allow to
// later use getblocktxn)
func (r *ChannelRouter) fetchChanPoint(chanID *lnwire.ShortChannelID) (*wire.OutPoint, 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\n", chanID.TxIndex,
numTxns-1, spew.Sdump(chanID))
}
// Finally once we have the block itself, we seek to the targeted
// transaction index to obtain the funding output and txid.
fundingTx := fundingBlock.Transactions[chanID.TxIndex]
return &wire.OutPoint{
Hash: fundingTx.TxHash(),
Index: uint32(chanID.TxPosition),
}, nil
}
// routingMsg couples a routing related routing topology update to the
// error channel.
type routingMsg struct {
msg interface{}
err chan error
}
// FindRoutes attempts to query the ChannelRouter for the all available paths
// to a particular target destination which is able to send `amt` after
// factoring in channel capacities and cumulative fees along each route route.
// To find all eligible paths, we use a modified version of Yen's algorithm
// which itself uses a modified version of Dijkstra's algorithm within its
// inner loop. Once we have a set of candidate routes, we calculate the
// required fee and time lock values running backwards along the route. The
// route that will be ranked the highest is the one with the lowest cumulative
// fee along the route.
func (r *ChannelRouter) FindRoutes(target *btcec.PublicKey, amt btcutil.Amount) ([]*Route, error) {
dest := target.SerializeCompressed()
log.Debugf("Searching for path to %x, sending %v", dest, amt)
// We can short circuit the routing by opportunistically checking to
// see if the target vertex event exists in the current graph.
if _, exists, err := r.cfg.Graph.HasLightningNode(target); err != nil {
return nil, err
} else if !exists {
log.Debugf("Target %x is not in known graph", dest)
return nil, newErrf(ErrTargetNotInNetwork, "target not found")
}
// Now that we know the destination is reachable within the graph,
// we'll execute our KSP algorithm to find the k-shortest paths from
// our source to the destination.
shortestPaths, err := findPaths(r.cfg.Graph, r.selfNode, target, amt)
if err != nil {
return nil, err
}
// Now that we have a set of paths, we'll need to turn them into
// *routes* by computing the required time-lock and fee information for
// each path. During this process, some paths may be discarded if they
// aren't able to support the total satoshis flow once fees have been
// factored in.
validRoutes := make(sortableRoutes, 0, len(shortestPaths))
for _, path := range shortestPaths {
// Attempt to make the path into a route. We snip off the first
// hop in the path as it contains a "self-hop" that is inserted
// by our KSP algorithm.
route, err := newRoute(amt, path[1:])
if err != nil {
continue
}
// If the path as enough total flow to support the computed
// route, then we'll add it to our set of valid routes.
validRoutes = append(validRoutes, route)
}
// If all our perspective routes were eliminating during the transition
// from path to route, then we'll return an error to the caller
if len(validRoutes) == 0 {
return nil, newErr(ErrNoPathFound, "unable to find a path to "+
"destination")
}
// Finally, we'll sort the set of validate routes to optimize for
// lowest total fees, using the required time-lock within the route as
// a tie-breaker.
sort.Sort(validRoutes)
log.Debugf("Obtained %v paths sending %v to %x: %v", len(validRoutes),
amt, dest, newLogClosure(func() string {
return spew.Sdump(validRoutes)
}),
)
return validRoutes, nil
}
// 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.
//
// TODO(roasbeef): add params for the per-hop payloads
func generateSphinxPacket(route *Route, paymentHash []byte) ([]byte, error) {
// First obtain all the public keys along the route which are contained
// in each hop.
nodes := make([]*btcec.PublicKey, len(route.Hops))
for i, hop := range route.Hops {
// We create a new instance of the public key to avoid possibly
// mutating the curve parameters, which are unset in a higher
// level in order to avoid spamming the logs.
pub := btcec.PublicKey{
Curve: btcec.S256(),
X: hop.Channel.Node.PubKey.X,
Y: hop.Channel.Node.PubKey.Y,
}
nodes[i] = &pub
}
// Next we generate the per-hop payload which gives each node within
// the route the necessary information (fees, CLTV value, etc) to
// properly forward the payment.
// TODO(roasbeef): properly set CLTV value, payment amount, and chain
// within hop payloads.
var hopPayloads [][]byte
for i := 0; i < len(route.Hops); i++ {
payload := bytes.Repeat([]byte{byte('A' + i)},
sphinx.HopPayloadSize)
hopPayloads = append(hopPayloads, payload)
}
sessionKey, err := btcec.NewPrivateKey(btcec.S256())
if err != nil {
return nil, err
}
// Next generate the onion routing packet which allows us to perform
// privacy preserving source routing across the network.
sphinxPacket, err := sphinx.NewOnionPacket(nodes, sessionKey,
hopPayloads, paymentHash)
if err != nil {
return nil, err
}
// Finally, encode Sphinx packet using it's wire representation to be
// included within the HTLC add packet.
var onionBlob bytes.Buffer
if err := sphinxPacket.Encode(&onionBlob); err != nil {
return nil, err
}
log.Tracef("Generated sphinx packet: %v",
newLogClosure(func() string {
// We unset the internal curve here in order to keep
// the logs from getting noisy.
sphinxPacket.Header.EphemeralKey.Curve = nil
return spew.Sdump(sphinxPacket)
}),
)
return onionBlob.Bytes(), 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 *btcec.PublicKey
// Amount is the value of the payment to send through the network in
// satoshis.
// TODO(roasbeef): this should be milli satoshis
Amount btcutil.Amount
// PaymentHash is the r-hash value to use within the HTLC extended to
// the first hop.
PaymentHash [32]byte
// TODO(roasbeef): add e2e message?
}
// 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, error) {
log.Tracef("Dispatching route for lightning payment: %v",
newLogClosure(func() string {
payment.Target.Curve = nil
return spew.Sdump(payment)
}),
)
var (
sendError error
preImage [32]byte
)
// TODO(roasbeef): consult KSP cache before dispatching
// Before attempting to perform a series of graph traversals to find
// the k-shortest paths to the destination, we'll first consult our
// path cache
rt := newRouteTuple(payment.Amount, payment.Target)
r.routeCacheMtx.RLock()
routes, ok := r.routeCache[rt]
r.routeCacheMtx.RUnlock()
// If we don't have a set of routes cached, we'll query the graph for a
// set of potential routes to the destination node that can support our
// payment amount. If no such routes can be found then an error will be
// returned.
if !ok {
freshRoutes, err := r.FindRoutes(payment.Target, payment.Amount)
if err != nil {
return preImage, nil, err
}
// Populate the cache with this set of fresh routes so we can
// reuse them in the future.
r.routeCacheMtx.Lock()
r.routeCache[rt] = freshRoutes
r.routeCacheMtx.Unlock()
routes = freshRoutes
}
// For each eligible path, we'll attempt to successfully send our
// target payment using the multi-hop route. We'll try each route
// serially until either once succeeds, or we've exhausted our set of
// available paths.
for _, route := range routes {
log.Tracef("Attempting to send payment %x, using route: %v",
payment.PaymentHash, newLogClosure(func() string {
return spew.Sdump(route)
}),
)
// Generate the raw encoded sphinx packet to be included along
// with the htlcAdd message that we send directly to the
// switch.
sphinxPacket, err := generateSphinxPacket(route, payment.PaymentHash[:])
if err != nil {
return preImage, 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: route.TotalAmount,
PaymentHash: payment.PaymentHash,
}
copy(htlcAdd.OnionBlob[:], sphinxPacket)
// 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 := route.Hops[0].Channel.Node.PubKey
preImage, sendError = r.cfg.SendToSwitch(firstHop, htlcAdd)
if sendError != nil {
log.Errorf("Attempt to send payment %x failed: %v",
payment.PaymentHash, sendError)
continue
}
return preImage, route, nil
}
// If we're unable to successfully make a payment using any of the
// routes we've found, then return an error.
return [32]byte{}, nil, sendError
}
// AddNode is used to add node to the topology of the router, after this node
// might be used in construction of payment path.
//
// 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:
return <-rMsg.err
case <-r.quit:
return errors.New("router has been shutted down")
}
}
// 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:
return <-rMsg.err
case <-r.quit:
return errors.New("router has been shutted down")
}
}
// 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:
return <-rMsg.err
case <-r.quit:
return errors.New("router has been shutted down")
}
}
// 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())
}
// 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(_ *bolt.Tx, n *channeldb.LightningNode) error {
return cb(n)
})
}
// ForAllOutgoingChannels is used to iterate over all outgiong channel owned by
// the router.
//
// NOTE: This method is part of the ChannelGraphSource interface.
func (r *ChannelRouter) ForAllOutgoingChannels(cb func(c *channeldb.ChannelEdgePolicy) error) error {
return r.selfNode.ForEachChannel(nil, func(_ *bolt.Tx, _ *channeldb.ChannelEdgeInfo,
c *channeldb.ChannelEdgePolicy) error {
return cb(c)
})
}
// 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)
}