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routing: modify newPath to take the preferred final CLTV delta of last hop

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In this commit, rather than reading the final CLTV delta from the
channel graph itself (which would require _both_ edges to be advertised
in order to route over), we now instead have moved to allowing the
receiving node to choose their own final CLTV delta.
This commit is contained in:
Olaoluwa Osuntokun 2017-10-18 21:43:53 -07:00
parent 65482faa79
commit 23b6d84493
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GPG Key ID: 964EA263DD637C21
1 changed files with 14 additions and 7 deletions
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21
routing/pathfind.go
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@ -211,7 +211,8 @@ func (r *Route) ToHopPayloads() []sphinx.HopData {
// NOTE: The passed slice of ChannelHops MUST be sorted in forward order: from // NOTE: The passed slice of ChannelHops MUST be sorted in forward order: from
// the source to the target node of the path finding attempt. // the source to the target node of the path finding attempt.
func newRoute(amtToSend lnwire.MilliSatoshi, sourceVertex vertex, func newRoute(amtToSend lnwire.MilliSatoshi, sourceVertex vertex,
pathEdges []*ChannelHop, currentHeight uint32) (*Route, error) { pathEdges []*ChannelHop, currentHeight uint32,
finalCLTVDelta uint16) (*Route, error) {
// First, we'll create a new empty route with enough hops to match the // First, we'll create a new empty route with enough hops to match the
// amount of path edges. We set the TotalTimeLock to the current block // amount of path edges. We set the TotalTimeLock to the current block
@ -298,17 +299,23 @@ func newRoute(amtToSend lnwire.MilliSatoshi, sourceVertex vertex,
nextHop.Fee = 0 nextHop.Fee = 0
} }
// Next, increment the total timelock of the entire route such
// that each hops time lock increases as we walk backwards in
// the route, using the delta of the previous hop.
route.TotalTimeLock += uint32(edge.TimeLockDelta)
// If this is the last hop, then for verification purposes, the // If this is the last hop, then for verification purposes, the
// value of the outgoing time-lock should be _exactly_ the // value of the outgoing time-lock should be _exactly_ the
// absolute time out they'd expect in the HTLC. // absolute time out they'd expect in the HTLC.
if i == len(pathEdges)-1 { if i == len(pathEdges)-1 {
nextHop.OutgoingTimeLock = currentHeight + uint32(edge.TimeLockDelta) // As this is the last hop, we'll use the specified
// final CLTV delta value instead of the value from the
// last link in the route.
route.TotalTimeLock += uint32(finalCLTVDelta)
nextHop.OutgoingTimeLock = currentHeight + uint32(finalCLTVDelta)
} else { } else {
// Next, increment the total timelock of the entire
// route such that each hops time lock increases as we
// walk backwards in the route, using the delta of the
// previous hop.
route.TotalTimeLock += uint32(edge.TimeLockDelta)
// Otherwise, the value of the outgoing time-lock will // Otherwise, the value of the outgoing time-lock will
// be the value of the time-lock for the _outgoing_ // be the value of the time-lock for the _outgoing_
// HTLC, so we factor in their specified grace period // HTLC, so we factor in their specified grace period