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routing: more efficient feature validation

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Also prepares for payload size tracking during pathfinding
This commit is contained in:
Joost Jager 2019-12-18 08:16:53 +01:00
parent 95ddab57fa
commit e546a2c42b
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GPG Key ID: A61B9D4C393C59C7
1 changed files with 62 additions and 30 deletions
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92
routing/pathfind.go
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@ -670,36 +670,6 @@ func findPath(g *graphParams, r *RestrictParams, cfg *PathFindingConfig,
edge.ChannelID)
}
switch {
// If this edge takes us to the final hop, we'll set the node
// features to those determined above. These are either taken
// from the destination features, e.g. virtual or invoice
// features, or loaded as a fallback from the graph. The
// transitive dependencies were already validated above, so no
// need to do so now.
//
// NOTE: This may overwrite features loaded from the graph if
// destination features were provided. This is fine though,
// since our route construction does not care where the features
// are actually taken from. In the future we may wish to do
// route construction within findPath, and avoid using
// ChannelEdgePolicy altogether.
case edge.Node.PubKeyBytes == target:
edge.Node.Features = features
// Otherwise, this is some other intermediary node. Verify the
// transitive feature dependencies for this node, and skip the
// channel if they are invalid.
default:
err := feature.ValidateDeps(edge.Node.Features)
if err != nil {
log.Tracef("Node %x has invalid features",
edge.Node.PubKeyBytes)
return
}
}
// All conditions are met and this new tentative distance is
// better than the current best known distance to this node.
// The new better distance is recorded, and also our "next hop"
@ -724,6 +694,44 @@ func findPath(g *graphParams, r *RestrictParams, cfg *PathFindingConfig,
// TODO(roasbeef): also add path caching
// * similar to route caching, but doesn't factor in the amount
// Cache features because we visit nodes multiple times.
featureCache := make(map[route.Vertex]*lnwire.FeatureVector)
// getGraphFeatures returns (cached) node features from the graph.
getGraphFeatures := func(node route.Vertex) (*lnwire.FeatureVector,
error) {
// Check cache for features of the fromNode.
fromFeatures, ok := featureCache[node]
if !ok {
targetNode, err := g.graph.FetchLightningNode(tx, node)
switch {
// If the node exists and has valid features, use them.
case err == nil:
err := feature.ValidateDeps(targetNode.Features)
if err == nil {
fromFeatures = targetNode.Features
}
// If an error other than the node not existing is hit,
// abort.
case err != channeldb.ErrGraphNodeNotFound:
return nil, err
// Otherwise, we couldn't find a node announcement,
// populate a blank feature vector.
default:
fromFeatures = lnwire.EmptyFeatureVector()
}
// Update cache.
featureCache[node] = fromFeatures
}
return fromFeatures, nil
}
routeToSelf := source == target
for {
nodesVisited++
@ -771,6 +779,17 @@ func findPath(g *graphParams, r *RestrictParams, cfg *PathFindingConfig,
continue
}
// Get feature vector for fromNode.
fromFeatures, err := getGraphFeatures(fromNode)
if err != nil {
return nil, err
}
// If there are no valid features, skip this node.
if fromFeatures == nil {
continue
}
// Check if this candidate node is better than what we
// already have.
processEdge(fromNode, policy, partialPath)
@ -818,6 +837,19 @@ func findPath(g *graphParams, r *RestrictParams, cfg *PathFindingConfig,
}
}
// For the final hop, we'll set the node features to those determined
// above. These are either taken from the destination features, e.g.
// virtual or invoice features, or loaded as a fallback from the graph.
// The transitive dependencies were already validated above, so no need
// to do so now.
//
// NOTE: This may overwrite features loaded from the graph if
// destination features were provided. This is fine though, since our
// route construction does not care where the features are actually
// taken from. In the future we may wish to do route construction within
// findPath, and avoid using ChannelEdgePolicy altogether.
pathEdges[len(pathEdges)-1].Node.Features = features
// The route is invalid if it spans more than 20 hops. The current
// Sphinx (onion routing) implementation can only encode up to 20 hops
// as the entire packet is fixed size. If this route is more than 20