routing: prune channels unidirectional
In this commit we introduce pruning of channel edges instead of channels. Channel failures apply to a single direction and it is unnecessarily restricting to prune both directions.
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5 files changed
+119
-71
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@@ -213,6 +213,45 @@ func newRouteTuple(amt lnwire.MilliSatoshi, dest []byte) routeTuple {
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return r
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}
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// edgeLocator is a struct used to identify a specific edge. The direction
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// fields takes the value of 0 or 1 and is identical in definition to the
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// channel direction flag. A value of 0 means the direction from the lower node
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// pubkey to the higher.
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type edgeLocator struct {
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channelID uint64
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direction uint8
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}
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// newEdgeLocatorByPubkeys returns an edgeLocator based on its end point
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// pubkeys.
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func newEdgeLocatorByPubkeys(channelID uint64, fromNode, toNode *Vertex) *edgeLocator {
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// Determine direction based on lexicographical ordering of both
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// pubkeys.
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var direction uint8
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if bytes.Compare(fromNode[:], toNode[:]) == 1 {
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direction = 1
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}
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return &edgeLocator{
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channelID: channelID,
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direction: direction,
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}
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}
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// newEdgeLocator extracts an edgeLocator based for a full edge policy
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// structure.
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func newEdgeLocator(edge *channeldb.ChannelEdgePolicy) *edgeLocator {
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return &edgeLocator{
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channelID: edge.ChannelID,
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direction: uint8(edge.Flags & lnwire.ChanUpdateDirection),
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}
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}
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// String returns a human readable version of the edgeLocator values.
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func (e *edgeLocator) String() string {
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return fmt.Sprintf("%v:%v", e.channelID, e.direction)
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}
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// ChannelRouter is the layer 3 router within the Lightning stack. Below the
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// ChannelRouter is the HtlcSwitch, and below that is the Bitcoin blockchain
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// itself. The primary role of the ChannelRouter is to respond to queries for
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@@ -1755,14 +1794,11 @@ func (r *ChannelRouter) sendPayment(payment *LightningPayment,
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errVertex := NewVertex(errSource)
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log.Tracef("node=%x reported failure when sending "+
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"htlc=%x", errSource.SerializeCompressed(),
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payment.PaymentHash[:])
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"htlc=%x", errVertex, payment.PaymentHash[:])
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// Always determine chan id ourselves, because a channel
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// update with id may not be available.
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failedChanID, err := getFailedChannelID(
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route, errVertex,
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)
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failedEdge, err := getFailedEdge(route, errVertex)
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if err != nil {
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return preImage, nil, err
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}
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@@ -1793,13 +1829,13 @@ func (r *ChannelRouter) sendPayment(payment *LightningPayment,
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// Or is there a valid reason for the channel
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// update to fail?
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if !updateOk {
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paySession.ReportChannelFailure(
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failedChanID,
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paySession.ReportEdgeFailure(
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failedEdge,
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)
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}
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paySession.ReportChannelPolicyFailure(
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NewVertex(errSource), failedChanID,
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paySession.ReportEdgePolicyFailure(
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NewVertex(errSource), failedEdge,
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)
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}
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@@ -1889,7 +1925,7 @@ func (r *ChannelRouter) sendPayment(payment *LightningPayment,
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// the update and continue.
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case *lnwire.FailChannelDisabled:
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r.applyChannelUpdate(&onionErr.Update, errSource)
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paySession.ReportChannelFailure(failedChanID)
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paySession.ReportEdgeFailure(failedEdge)
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continue
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// It's likely that the outgoing channel didn't have
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@@ -1897,7 +1933,7 @@ func (r *ChannelRouter) sendPayment(payment *LightningPayment,
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// now, and continue onwards with our path finding.
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case *lnwire.FailTemporaryChannelFailure:
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r.applyChannelUpdate(onionErr.Update, errSource)
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paySession.ReportChannelFailure(failedChanID)
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paySession.ReportEdgeFailure(failedEdge)
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continue
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// If the send fail due to a node not having the
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@@ -1922,7 +1958,7 @@ func (r *ChannelRouter) sendPayment(payment *LightningPayment,
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// returning errors in order to attempt to black list
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// another node.
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case *lnwire.FailUnknownNextPeer:
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paySession.ReportChannelFailure(failedChanID)
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paySession.ReportEdgeFailure(failedEdge)
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continue
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// If the node wasn't able to forward for which ever
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@@ -1950,10 +1986,17 @@ func (r *ChannelRouter) sendPayment(payment *LightningPayment,
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continue
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// If we get a permanent channel or node failure, then
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// we'll note this (exclude the vertex/edge), and
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// we'll prune the channel in both directions and
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// continue with the rest of the routes.
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case *lnwire.FailPermanentChannelFailure:
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paySession.ReportChannelFailure(failedChanID)
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paySession.ReportEdgeFailure(&edgeLocator{
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channelID: failedEdge.channelID,
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direction: 0,
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})
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paySession.ReportEdgeFailure(&edgeLocator{
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channelID: failedEdge.channelID,
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direction: 1,
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})
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continue
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default:
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@@ -1965,43 +2008,43 @@ func (r *ChannelRouter) sendPayment(payment *LightningPayment,
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}
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}
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// getFailedChannelID tries to locate the failing channel given a route and the
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// getFailedEdge tries to locate the failing channel given a route and the
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// pubkey of the node that sent the error. It will assume that the error is
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// associated with the outgoing channel of the error node.
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func getFailedChannelID(route *Route, errSource Vertex) (
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uint64, error) {
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// If the error originates from ourselves, report our outgoing channel
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// as failing.
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if errSource == route.SourcePubKey {
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return route.Hops[0].ChannelID, nil
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}
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func getFailedEdge(route *Route, errSource Vertex) (
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*edgeLocator, error) {
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hopCount := len(route.Hops)
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fromNode := route.SourcePubKey
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for i, hop := range route.Hops {
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if errSource != hop.PubKeyBytes {
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continue
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}
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toNode := hop.PubKeyBytes
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// If the errSource is the final hop, we assume that the
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// failing channel is the incoming channel.
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// Determine if we have a failure from the final hop.
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//
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// TODO(joostjager): In this case, certain types of
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// errors are not expected. For example
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// FailUnknownNextPeer. This could be a reason to prune
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// the node?
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if i == hopCount-1 {
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return route.Hops[i].ChannelID, nil
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// TODO(joostjager): In this case, certain types of errors are
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// not expected. For example FailUnknownNextPeer. This could be
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// a reason to prune the node?
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finalHopFailing := i == hopCount-1 && errSource == toNode
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// As this error indicates that the target channel was unable to
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// carry this HTLC (for w/e reason), we'll return the _outgoing_
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// channel that the source of the error was meant to pass the
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// HTLC along to.
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//
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// If the errSource is the final hop, we assume that the failing
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// channel is the incoming channel.
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if errSource == fromNode || finalHopFailing {
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return newEdgeLocatorByPubkeys(
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hop.ChannelID,
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&fromNode,
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&toNode,
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), nil
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}
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// As this error indicates that the target channel was
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// unable to carry this HTLC (for w/e reason), we'll
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// query return the _outgoing_ channel that the source
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// of the error was meant to pass the HTLC along to.
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return route.Hops[i+1].ChannelID, nil
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fromNode = toNode
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}
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return 0, fmt.Errorf("cannot find error source node in route")
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return nil, fmt.Errorf("cannot find error source node in route")
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}
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// applyChannelUpdate validates a channel update and if valid, applies it to the
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