lnd.xprv/channeldb/graph.go
Olaoluwa Osuntokun 12538ea922
channeldb: add support for channel graph pruning
This commit adds support for channel graph pruning, which is the method
used to keep the channel graph in sync with the current UTXO state. As
the channel graph is essentially simply a subset of the UTXO set, by
evaluating the channel graph with the set of outfits spent within a
block, then we’re able to prune channels that’ve been closed by
spending their funding outpoint. A new method `PruneGraph` has been
provided which implements the described functionality.

Upon start up any upper routing layers should sync forward in the chain
pruning the channel graph with each newly found block. In order to
facilitate such channel graph reconciliation a new method `PruneTip`
has been added which allows callers to query current pruning state of
the channel graph.
2016-12-27 16:43:12 -08:00

1261 lines
37 KiB
Go

package channeldb
import (
"bytes"
"encoding/binary"
"image/color"
"io"
"net"
"time"
"github.com/boltdb/bolt"
"github.com/roasbeef/btcd/btcec"
"github.com/roasbeef/btcd/wire"
"github.com/roasbeef/btcutil"
)
var (
// nodeBucket is a bucket which houses all the vertices or nodes within
// the channel graph. This bucket has a single-sub bucket which adds an
// additional index from pubkey -> alias. Within the top-level of this
// bucket, the key space maps a node's compressed public key to the
// serialized information for that node. Additionally, there's a
// special key "source" which stores the pubkey of the source node. The
// source node is used as the starting point for all graph/queries and
// traversals. The graph is formed as a star-graph with the source node
// at the center.
//
// maps: pubKey -> nofInfo
// maps: source -> selfPubKey
nodeBucket = []byte("graph-node")
// sourceKey is a special key that resides within the nodeBucket. The
// sourceKey maps a key to the public key of the "self node".
sourceKey = []byte("source")
// aliasIndexBucket is a sub-bucket that's nested within the main
// nodeBucket. This bucket maps the public key of a node to it's
// current alias. This bucket is provided as it can be used within a
// future UI layer to add an additional degree of confirmation.
aliasIndexBucket = []byte("alias")
// edgeBucket is a bucket which houses all of the edge or channel
// information within the channel graph. This bucket essentially acts
// as an adjacency list, which in conjunction with a range scan, can be
// used to iterate over all the _outgoing_ edges for a particular node.
// Key in the bucket use a prefix scheme which leads with the node's
// public key and sends with the compact edge ID. For each edgeID,
// there will be two entries within the bucket, as the graph is
// directed: nodes may have different policies w.r.t to fees for their
// respective directions.
//
// maps: pubKey || edgeID -> edge for node
edgeBucket = []byte("graph-edge")
// chanStart is an array of all zero bytes which is used to perform
// range scans within the edgeBucket to obtain all of the outgoing
// edges for a particular node.
chanStart [8]byte
// edgeIndexBucket is an index which can be used to iterate all edges
// in the bucket, grouping them according to their in/out nodes. This
// bucket resides within the edgeBucket above. Creation of a edge
// proceeds in two phases: first the edge is added to the edge index,
// afterwards the edgeBucket can be updated with the latest details of
// the edge as they are announced on the network.
//
// maps: chanID -> pub1 || pub2
edgeIndexBucket = []byte("edge-index")
// channelPointBucket maps a channel's full outpoint (txid:index) to
// its short 8-byte channel ID. This bucket resides within the
// edgeBucket above, and can be used to quickly remove an edge due to
// the outpoint being spent, or to query for existence of a channel.
//
// maps: outPoint -> chanID
channelPointBucket = []byte("chan-index")
// graphMetaBucket is a top-level bucket which stores various meta-deta
// related to the on-disk channel graph. Data strored in this bucket
// includes the block to which the graph has been synced to, the total
// number of channels, etc.
graphMetaBucket = []byte("graph-meta")
// pruneTipKey is a key within the above graphMetaBucket that stores
// the best known blockhash+height that the channel graph has been
// known to be pruned to. Once a new block is discovered, any channels
// that have been closed (by spending the outpoint) can safely be
// removed from the graph.
pruneTipKey = []byte("prune-tip")
edgeBloomKey = []byte("edge-bloom")
nodeBloomKey = []byte("node-bloom")
)
// ChannelGraph is a persistent, on-disk graph representation of the Lightning
// Network. This struct can be used to implement path finding algorithms on top
// of, and also to update a node's view based on information received from the
// p2p network. Internally, the graph is stored using a modified adjacency list
// representation with some added object interaction possible with each
// serialized edge/node. The graph is stored is directed, meaning that are two
// edges stored for each channel: an inbound/outbound edge for each node pair.
// Nodes, edges, and edge information can all be added to the graph
// independently. Edge removal results in the deletion of all edge information
// for that edge.
type ChannelGraph struct {
db *DB
// TODO(roasbeef): store and update bloom filter to reduce disk access
// due to current gossip model
// * LRU cache for edges?
}
// ForEachChannel iterates through all the channel edges stored within the
// graph and invokes the passed callback for each edge. The callback takes two
// edges as since this is a directed graph, both the in/out edges are visited.
// If the callback returns an error, then the transaction is aborted and the
// iteration stops early.
func (c *ChannelGraph) ForEachChannel(cb func(*ChannelEdge, *ChannelEdge) error) error {
// TODO(roasbeef): ptr map to reduce # of allocs? no duplicates
return c.db.View(func(tx *bolt.Tx) error {
// First, grab the node bucket. This will be used to populate
// the Node pointers in each edge read from disk.
nodes := tx.Bucket(nodeBucket)
if nodes == nil {
return ErrGraphNotFound
}
// Next, grab the edge bucket which stores the edges, and also
// the index itself so we can group the directed edges together
// logically.
edges := tx.Bucket(edgeBucket)
if edges == nil {
return ErrGraphNodesNotFound
}
edgeIndex := edges.Bucket(edgeIndexBucket)
if edgeIndex == nil {
return ErrGraphNodesNotFound
}
// For each edge pair within the edge index, we fetch each edge
// itself and also the node information in order to fully
// populated the objecvt.
return edgeIndex.ForEach(func(chanID, edgeInfo []byte) error {
// The first node is contained within the first half of
// the edge information.
node1Pub := edgeInfo[:33]
edge1, err := fetchChannelEdge(edges, chanID, node1Pub, nodes)
if err != nil {
return err
}
edge1.db = c.db
edge1.Node.db = c.db
// Similarly, the second node is contained within the
// latter half of the edge information.
node2Pub := edgeInfo[33:]
edge2, err := fetchChannelEdge(edges, chanID, node2Pub, nodes)
if err != nil {
return err
}
edge2.db = c.db
edge2.Node.db = c.db
// With both edges read, execute the call back. IF this
// function returns an error then the transaction will
// be aborted.
return cb(edge1, edge2)
})
})
}
// ForEachNode iterates through all the stored vertices/nodes in the graph,
// executing the passed callback with each node encountered. If the callback
// returns an error, then the transaction is aborted and the iteration stops
// early.
func (c *ChannelGraph) ForEachNode(cb func(*LightningNode) error) error {
// TODO(roasbeef): need to also pass in a transaction? or reverse order
// to get all in memory THEN execute callback?
return c.db.View(func(tx *bolt.Tx) error {
// First grab the nodes bucket which stores the mapping from
// pubKey to node information.
nodes := tx.Bucket(nodeBucket)
if nodes == nil {
return ErrGraphNotFound
}
return nodes.ForEach(func(pubKey, nodeBytes []byte) error {
// If this is the source key, then we skip this
// iteration as the value for this key is a pubKey
// rather than raw node information.
if bytes.Equal(pubKey, sourceKey) || len(pubKey) != 33 {
return nil
}
nodeReader := bytes.NewReader(nodeBytes)
node, err := deserializeLightningNode(nodeReader)
if err != nil {
return err
}
node.db = c.db
// Execute the callback, the transaction will abort if
// this returns an error.
return cb(node)
})
})
}
// SourceNode returns the source node of the graph. The source node is treated
// as the center node within a star-graph. This method may be used to kick-off
// a path finding algorithm in order to explore the reachability of another
// node based off the source node.
func (r *ChannelGraph) SourceNode() (*LightningNode, error) {
var source *LightningNode
err := r.db.View(func(tx *bolt.Tx) error {
// First grab the nodes bucket which stores the mapping from
// pubKey to node information.
nodes := tx.Bucket(nodeBucket)
if nodes == nil {
return ErrGraphNotFound
}
selfPub := nodes.Get(sourceKey)
if selfPub == nil {
return ErrSourceNodeNotSet
}
// With the pubKey of the source node retrieved, we're able to
// fetch the full node information.
node, err := fetchLightningNode(nodes, selfPub)
if err != nil {
return err
}
source = node
source.db = r.db
return nil
})
if err != nil {
return nil, err
}
return source, nil
}
// SetSourceNode sets the source node within the graph database. The source
// node is to be used as the center of a star-graph within path finding
// algorithms.
func (r *ChannelGraph) SetSourceNode(node *LightningNode) error {
nodePub := node.PubKey.SerializeCompressed()
return r.db.Update(func(tx *bolt.Tx) error {
// First grab the nodes bucket which stores the mapping from
// pubKey to node information.
nodes, err := tx.CreateBucketIfNotExists(nodeBucket)
if err != nil {
return err
}
// Next we create the mapping from source to the targeted
// public key.
if err := nodes.Put(sourceKey, nodePub); err != nil {
return err
}
// Finally, we commit the information of the lightning node
// itself.
return addLightningNode(tx, node)
})
}
// AddLightningNode adds a new (unconnected) vertex/node to the graph database.
// When adding an edge, each node must be added before the edge can be
// inserted. Afterwards the edge information can then be updated.
func (r *ChannelGraph) AddLightningNode(node *LightningNode) error {
return r.db.Update(func(tx *bolt.Tx) error {
return addLightningNode(tx, node)
})
}
func addLightningNode(tx *bolt.Tx, node *LightningNode) error {
nodes, err := tx.CreateBucketIfNotExists(nodeBucket)
if err != nil {
return err
}
aliases, err := nodes.CreateBucketIfNotExists(aliasIndexBucket)
if err != nil {
return err
}
return putLightningNode(nodes, aliases, node)
}
// LookupAlias attempts to return the alias as advertised by the target node.
// TODO(roasbeef): currently assumes that aliases are unique...
func (r *ChannelGraph) LookupAlias(pub *btcec.PublicKey) (string, error) {
var alias string
err := r.db.View(func(tx *bolt.Tx) error {
nodes := tx.Bucket(nodeBucket)
if nodes == nil {
return ErrGraphNodesNotFound
}
aliases := nodes.Bucket(aliasIndexBucket)
if aliases == nil {
return ErrGraphNodesNotFound
}
nodePub := pub.SerializeCompressed()
a := aliases.Get(nodePub)
if a == nil {
return ErrNodeAliasNotFound
}
// TODO(roasbeef): should actually be using the utf-8
// package...
alias = string(a)
return nil
})
if err != nil {
return "", err
}
return alias, nil
}
// DeleteLightningNode removes a vertex/node from the database according to the
// node's public key.
func (r *ChannelGraph) DeleteLightningNode(nodePub *btcec.PublicKey) error {
pub := nodePub.SerializeCompressed()
// TODO(roasbeef): ensure dangling edges are removed...
return r.db.Update(func(tx *bolt.Tx) error {
nodes, err := tx.CreateBucketIfNotExists(nodeBucket)
if err != nil {
return err
}
aliases, err := tx.CreateBucketIfNotExists(aliasIndexBucket)
if err != nil {
return err
}
if err := aliases.Delete(pub); err != nil {
return err
}
return nodes.Delete(pub)
})
}
// AddChannelEdge adds a new (undirected, blank) edge to the graph database. An
// undirected edge from the two target nodes are created. The chanPoint and
// chanID are used to uniquely identify the edge globally within the database.
func (r *ChannelGraph) AddChannelEdge(from, to *btcec.PublicKey,
chanPoint *wire.OutPoint, chanID uint64) error {
// Construct the channel's primary key which is the 8-byte channel ID.
var chanKey [8]byte
binary.BigEndian.PutUint64(chanKey[:], chanID)
var (
node1 []byte
node2 []byte
)
fromBytes := from.SerializeCompressed()
toBytes := to.SerializeCompressed()
// On-disk, we order the value for the edge's key with the "smaller"
// pubkey coming before the larger one. This ensures that all edges
// have a deterministic ordering.
if bytes.Compare(fromBytes, toBytes) == -1 {
node1 = fromBytes
node2 = toBytes
} else {
node1 = toBytes
node2 = fromBytes
}
return r.db.Update(func(tx *bolt.Tx) error {
edges, err := tx.CreateBucketIfNotExists(edgeBucket)
if err != nil {
return err
}
edgeIndex, err := edges.CreateBucketIfNotExists(edgeIndexBucket)
if err != nil {
return err
}
chanIndex, err := edges.CreateBucketIfNotExists(channelPointBucket)
if err != nil {
return err
}
// First, attempt to check if this edge has already been
// created. If so, then we can exit early as this method is
// meant to be idempotent.
if edgeInfo := edgeIndex.Get(chanIDKey[:]); edgeInfo != nil {
return nil
}
// If the edge hasn't been created yet, then we'll first add it
// to the edge index in order to associate the edge between two
// nodes.
var edgeInfo [66]byte
copy(edgeInfo[:33], node1)
copy(edgeInfo[33:], node2)
if err := edgeIndex.Put(chanKey[:], edgeInfo[:]); err != nil {
return err
}
// Finally we add it to the channel index which maps channel
// points (outpoints) to the shorter channel ID's.
var b bytes.Buffer
if err := writeOutpoint(&b, chanPoint); err != nil {
return err
}
return chanIndex.Put(b.Bytes(), chanKey[:])
})
}
// HasChannelEdge returns true if the database knows of a channel edge with the
// passed channel ID, and false otherwise.
func (r *ChannelGraph) HasChannelEdge(chanID uint64) (bool, error) {
// TODO(roasbeef): check internal bloom filter first
var b bool
err := r.db.View(func(tx *bolt.Tx) error {
edges := tx.Bucket(edgeBucket)
if edges == nil {
return ErrGraphNoEdgesFound
}
edgeIndex := edges.Bucket(edgeIndexBucket)
if edgeIndex == nil {
return ErrGraphNoEdgesFound
}
var channelID [8]byte
byteOrder.PutUint64(channelID[:], chanID)
if edgeIndex.Get(channelID[:]) != nil {
b = true
}
return nil
})
if err != nil {
return b, err
}
return b, err
}
const (
// pruneTipBytes is the total size of the value which stores the
// current prune tip of the graph. The prune tip indicates if the
// channel graph is in sync with the current UTXO state. The structure
// is: blockHash || blockHeight, taking 36 bytes total.
pruneTipBytes = 32 + 4
)
// PruneGraph prunes newly closed channels from the channel graph in response
// to a new block being solved on the network. Any transactions which spend the
// funding output of any known channels withint he graph will be deleted.
// Additionally, the "prune tip", or the last block which has been used to
// prune the graph is stored so callers can ensure the graph is fully in sync
// with the current UTXO state. An integer is returned which reflects the
// number of channels pruned due to the new incoming block.
func (r *ChannelGraph) PruneGraph(spentOutputs []*wire.OutPoint,
blockHash *wire.ShaHash, blockHeight uint32) (uint32, error) {
var numChans uint32
err := r.db.Update(func(tx *bolt.Tx) error {
// First grab the edges bucket which houses the information
// we'd like to delete
edges, err := tx.CreateBucketIfNotExists(edgeBucket)
if err != nil {
return err
}
// Next grab the two edge indexes which will also need to be updated.
edgeIndex, err := edges.CreateBucketIfNotExists(edgeIndexBucket)
if err != nil {
return err
}
chanIndex, err := edges.CreateBucketIfNotExists(channelPointBucket)
if err != nil {
return err
}
// For each of the outpoints that've been spent within the
// block, we attempt to delete them from the graph as if that
// outpoint was a channel, then it has now been closed.
for _, chanPoint := range spentOutputs {
// TODO(roasbeef): load channel bloom filter, continue
// if NOT if filter
// Attempt to delete the channel, and ErrEdgeNotFound
// will be returned if that outpoint isn't known to be
// a channel. If no error is returned, then a channel
// was successfully pruned.
err := delChannelByEdge(edges, edgeIndex, chanIndex,
chanPoint)
if err != nil && err != ErrEdgeNotFound {
return err
} else if err == nil {
numChans += 1
}
}
metaBucket, err := tx.CreateBucketIfNotExists(graphMetaBucket)
if err != nil {
return err
}
// With the graph pruned, update the current "prune tip" which
// can eb used to check if the graph is fully synced with the
// current UTXO state.
var newTip [pruneTipBytes]byte
copy(newTip[:], blockHash[:])
byteOrder.PutUint32(newTip[32:], uint32(blockHeight))
return metaBucket.Put(pruneTipKey, newTip[:])
})
if err != nil {
return 0, err
}
return numChans, nil
}
// PruneTip returns the block height and hash of the latest block that has been
// used to prune channels in the graph. Knowing the "prune tip" allows callers
// to tell if the graph is currently in sync with the current best known UTXO
// state.
func (r *ChannelGraph) PruneTip() (*wire.ShaHash, uint32, error) {
var (
currentTip [pruneTipBytes]byte
tipHash wire.ShaHash
tipHeight uint32
)
err := r.db.View(func(tx *bolt.Tx) error {
graphMeta := tx.Bucket(graphMetaBucket)
if graphMeta == nil {
return ErrGraphNotFound
}
tipBytes := graphMeta.Get(pruneTipKey)
if tipBytes == nil {
return ErrGraphNeverPruned
}
copy(currentTip[:], tipBytes)
return nil
})
if err != nil {
return nil, 0, err
}
// Once we have the prune tip, the first 32 bytes are the block hash,
// with the latter 4 bytes being the block height.
copy(tipHash[:], currentTip[:32])
tipHeight = byteOrder.Uint32(currentTip[32:])
return &tipHash, tipHeight, nil
}
// DeleteChannelEdge removes an edge from the database as identified by it's
// funding outpoint. If the edge does not exist within the database, then this
func (r *ChannelGraph) DeleteChannelEdge(chanPoint *wire.OutPoint) error {
// TODO(roasbeef): possibly delete from node bucket if node has no more
// channels
// TODO(roasbeef): don't delete both edges?
return r.db.Update(func(tx *bolt.Tx) error {
// First grab the edges bucket which houses the information
// we'd like to delete
edges, err := tx.CreateBucketIfNotExists(edgeBucket)
if err != nil {
return err
}
// Next grab the two edge indexes which will also need to be updated.
edgeIndex, err := edges.CreateBucketIfNotExists(edgeIndexBucket)
if err != nil {
return err
}
chanIndex, err := edges.CreateBucketIfNotExists(channelPointBucket)
if err != nil {
return err
}
return delChannelByEdge(edges, edgeIndex, chanIndex, chanPoint)
})
}
func delChannelByEdge(edges *bolt.Bucket, edgeIndex *bolt.Bucket,
chanIndex *bolt.Bucket, chanPoint *wire.OutPoint) error {
var b bytes.Buffer
if err := writeOutpoint(&b, chanPoint); err != nil {
return err
}
// If the channel's outpoint doesn't exist within the outpoint
// index, then the edge does not exist.
chanID := chanIndex.Get(b.Bytes())
if chanID == nil {
return ErrEdgeNotFound
}
// Otherwise we obtain the two public keys from the mapping:
// chanID -> pubKey1 || pubKey2. With this, we can construct
// the keys which house both of the directed edges for this
// channel.
nodeKeys := edgeIndex.Get(chanID)
// The edge key is of the format pubKey || chanID. First we
// construct the latter half, populating the channel ID.
var edgeKey [33 + 8]byte
copy(edgeKey[33:], chanID)
// With the latter half constructed, copy over the first public
// key to delete the edge in this direction, then the second to
// delete the edge in the opposite direction.
copy(edgeKey[:33], nodeKeys[:33])
if edges.Get(edgeKey[:]) != nil {
if err := edges.Delete(edgeKey[:]); err != nil {
return err
}
}
copy(edgeKey[:33], nodeKeys[33:])
if edges.Get(edgeKey[:]) != nil {
if err := edges.Delete(edgeKey[:]); err != nil {
return err
}
}
// Finally, with the edge data deleted, we can purge the
// information from the two edge indexes.
if err := edgeIndex.Delete(chanID); err != nil {
return err
}
return chanIndex.Delete(b.Bytes())
}
// UpdateEdgeInfo updates the edge information for a single directed edge
// within the database for the referenced channel. The `flags` attribute within
// the ChannelEdge determines which of the directed edges are being updated. If
// the flag is 1, then the first node's information is being updated, otherwise
// it's the second node's information.
func (r *ChannelGraph) UpdateEdgeInfo(edge *ChannelEdge) error {
return r.db.Update(func(tx *bolt.Tx) error {
edges, err := tx.CreateBucketIfNotExists(edgeBucket)
if err != nil {
return err
}
edgeIndex, err := edges.CreateBucketIfNotExists(edgeIndexBucket)
if err != nil {
return err
}
// Create the channelID key be converting the channel ID
// integer into a byte slice.
var chanID [8]byte
byteOrder.PutUint64(chanID[:], edge.ChannelID)
// With the channel ID, we then fetch the value storing the two
// nodes which connect this channel edge.
nodeInfo := edgeIndex.Get(chanID[:])
if nodeInfo == nil {
return ErrEdgeNotFound
}
// Depending on the flags value parsed above, either the first
// or second node is being updated.
var fromNode, toNode []byte
if edge.Flags == 0 {
fromNode = nodeInfo[:33]
toNode = nodeInfo[33:]
} else {
fromNode = nodeInfo[33:]
toNode = nodeInfo[:33]
}
// Finally, with the direction of the edge being updated
// identified, we update the on-disk edge representation.
return putChannelEdge(edges, edge, fromNode, toNode)
})
}
// LightningNode represents an individual vertex/node within the channel graph.
// A node is connected to other nodes by one or more channel edges emanating
// from it. As the graph is directed, a node will also have an incoming edge
// attached to it for each outgoing edge.
type LightningNode struct {
// LastUpdate is the last time the vertex information for this node has
// been updated.
LastUpdate time.Time
// Address is the TCP address this node is reachable over.
Address *net.TCPAddr
// PubKey is the node's long-term identity public key. This key will be
// used to authenticated any advertisements/updates sent by the node.
PubKey *btcec.PublicKey
// Color is the selected color for the node.
Color color.RGBA
// Alias is a nick-name for the node. The alias can be used to confirm
// a node's identity or to serve as a short ID for an address book.
Alias string
db *DB
// TODO(roasbeef): discovery will need storage to keep it's last IP
// address and re-announce if interface changes?
// TODO(roasbeef): add update method and fetch?
}
// FetchLightningNode...
func (c *ChannelGraph) FetchLightningNode(pub *btcec.PublicKey) (*LightningNode, error) {
node := &LightningNode{db: c.db}
nodePub := pub.SerializeCompressed()
err := c.db.View(func(tx *bolt.Tx) error {
// First grapb the nodes bucket which stores the mapping from
// pubKey to node information.
nodes := tx.Bucket(nodeBucket)
if nodes == nil {
return ErrGraphNotFound
}
// If a key for this serialized public key isn't found, then
// the target node doesn't exist within the database.
nodeBytes := nodes.Get(nodePub)
if nodeBytes == nil {
return ErrGraphNodeNotFound
}
// If the node is found, then we can de deserialize the node
// information to return to the user.
nodeReader := bytes.NewReader(nodeBytes)
n, err := deserializeLightningNode(nodeReader)
if err != nil {
return err
}
n.db = c.db
node = n
return nil
})
if err != nil {
return nil, err
}
return node, nil
}
// ForEachChannel iterates through all the outgoing channel edges from this
// node, executing the passed callback with each edge as its sole argument. If
// the callback returns an error, then the iteration is halted with the error
// propagated back up to the caller. If the caller wishes to re-use an existing
// boltdb transaction, then it should be passed as the first argument.
// Otherwise the first argument should be nil and a fresh transaction will be
// created to execute the graph traversal.
func (l *LightningNode) ForEachChannel(tx *bolt.Tx, cb func(*ChannelEdge) error) error {
nodePub := l.PubKey.SerializeCompressed()
traversal := func(tx *bolt.Tx) error {
nodes := tx.Bucket(nodeBucket)
if nodes == nil {
return ErrGraphNotFound
}
edges := tx.Bucket(edgeBucket)
if edges == nil {
return ErrGraphNotFound
}
// In order to reach all the edges for this node, we take
// advantage of the construction of the key-space within the
// edge bucket. The keys are stored in the form: pubKey ||
// chanID. Therefore, starting from a chanID of zero, we can
// scan forward int he bucket, grabbing all the edges for the
// node. Once the prefix no longer matches, then we know we're
// done.
var nodeStart [33 + 8]byte
copy(nodeStart[:], nodePub)
copy(nodeStart[33:], chanStart[:])
// Starting from the key pubKey || 0, we seek forward in the
// bucket until the retrieved key no longer has the public key
// as its prefix. This indicates that we've stepped over into
// another node's edges, so we can terminate our scan.
edgeCursor := edges.Cursor()
for nodeEdge, edgeInfo := edgeCursor.Seek(nodeStart[:]); bytes.HasPrefix(nodeEdge, nodePub); nodeEdge, edgeInfo = edgeCursor.Next() {
// If the prefix still matches, then the value is the
// raw edge information. So we can now serialize the
// edge info and fetch the outgoing node in order to
// retrieve the full channel edge.
edgeReader := bytes.NewReader(edgeInfo)
edge, err := deserializeChannelEdge(edgeReader, nodes)
if err != nil {
return err
}
edge.db = l.db
edge.Node.db = l.db
// Finally, we execute the callback.
if err := cb(edge); err != nil {
return err
}
}
return nil
}
// If no transaction was provided, then we'll create a new transaction
// to execute the transaction within.
if tx == nil {
return l.db.View(traversal)
}
// Otherwise, we re-use the existing transaction to execute the graph
// traversal.
return traversal(tx)
}
// ChannelEdge represents a *directed* edge within the channel graph. For each
// channel in the database, there are two distinct edges: one for each possible
// direction of travel along the channel. The edges themselves hold information
// concerning fees, and minimum time-lock information which is utilized during
// path finding.
type ChannelEdge struct {
// ChannelID is the unique channel ID for the channel. The first 3
// bytes are the block height, the next 3 the index within the block,
// and the last 2 bytes are the output index for the channel.
// TODO(roasbeef): spell out and use index of channel ID to do fast look
// ups?
ChannelID uint64
// ChannelPoint is the funding outpoint of the channel. This can be
// used to uniquely identify the channel within the channel graph.
ChannelPoint wire.OutPoint
// LastUpdate is the last time an authenticated edge for this channel
// was received.
LastUpdate time.Time
// Flags is a bitfield which signals the capabilities of the channel as
// well as the directe edge this update applies to.
// TODO(roasbeef): make into wire struct
Flags uint16
// Expiry is the number of blocks this node will subtract from the
// expiry of an incoming HTLC. This value expresses the time buffer the
// node would like to HTLC exchanges.
Expiry uint16
// MinHTLC is the smallest value HTLC this node will accept, expressed
// in millisatoshi.
MinHTLC btcutil.Amount
// FeeBaseMSat is the base HTLC fee that will be charged for forwarding
// ANY HTLC, expressed in mSAT's.
FeeBaseMSat btcutil.Amount
// FeeProportionalMillionths is the rate that the node will charge for
// HTLC's for each millionth of a satoshi forwarded.
FeeProportionalMillionths btcutil.Amount
// Capacity is the total capacity of the channel, this is determined by
// the value output in the outpoint that created this channel.
Capacity btcutil.Amount
// Node is the LightningNode that this directed edge leads to. Using
// this pointer the channel graph can further be traversed.
Node *LightningNode
db *DB
}
// FetchChannelEdgesByOutpoint attempts to lookup the two directed edges for
// the channel identified by the funding outpoint. If the channel can't be
// found, then ErrEdgeNotFound is returned.
func (c *ChannelGraph) FetchChannelEdgesByOutpoint(op *wire.OutPoint) (*ChannelEdge, *ChannelEdge, error) {
var (
edge1 *ChannelEdge
edge2 *ChannelEdge
)
err := c.db.Update(func(tx *bolt.Tx) error {
// First, grab the node bucket. This will be used to populate
// the Node pointers in each edge read from disk.
nodes, err := tx.CreateBucketIfNotExists(nodeBucket)
if err != nil {
return err
}
// Next, grab the edge bucket which stores the edges, and also
// the index itself so we can group the directed edges together
// logically.
edges, err := tx.CreateBucketIfNotExists(edgeBucket)
if err != nil {
return err
}
edgeIndex, err := edges.CreateBucketIfNotExists(edgeIndexBucket)
if err != nil {
return err
}
// If the channel's outpoint doesn't exist within the outpoint
// index, then the edge does not exist.
chanIndex, err := edges.CreateBucketIfNotExists(channelPointBucket)
if err != nil {
return err
}
var b bytes.Buffer
if err := writeOutpoint(&b, op); err != nil {
return err
}
chanID := chanIndex.Get(b.Bytes())
if chanID == nil {
return ErrEdgeNotFound
}
e1, e2, err := fetchEdges(edgeIndex, edges, nodes, chanID, c.db)
if err != nil {
return err
}
edge1 = e1
edge2 = e2
return nil
})
if err != nil {
return nil, nil, err
}
return edge1, edge2, nil
}
// FetchChannelEdgesByID attempts to lookup the two directed edges for the
// channel identified by the channel ID. If the channel can't be found, then
// ErrEdgeNotFound is returned.
func (c *ChannelGraph) FetchChannelEdgesByID(chanID uint64) (*ChannelEdge, *ChannelEdge, error) {
var (
edge1 *ChannelEdge
edge2 *ChannelEdge
channelID [8]byte
)
err := c.db.Update(func(tx *bolt.Tx) error {
// First, grab the node bucket. This will be used to populate
// the Node pointers in each edge read from disk.
nodes, err := tx.CreateBucketIfNotExists(nodeBucket)
if err != nil {
return err
}
// Next, grab the edge bucket which stores the edges, and also
// the index itself so we can group the directed edges together
// logically.
edges, err := tx.CreateBucketIfNotExists(edgeBucket)
if err != nil {
return err
}
edgeIndex, err := edges.CreateBucketIfNotExists(edgeIndexBucket)
if err != nil {
return err
}
byteOrder.PutUint64(channelID[:], chanID)
e1, e2, err := fetchEdges(edgeIndex, edges, nodes,
channelID[:], c.db)
if err != nil {
return err
}
edge1 = e1
edge2 = e2
return nil
})
if err != nil {
return nil, nil, err
}
return edge1, edge2, nil
}
// NewChannelEdge returns a new blank ChannelEdge.
func (c *ChannelGraph) NewChannelEdge() *ChannelEdge {
return &ChannelEdge{db: c.db}
}
func putLightningNode(nodeBucket *bolt.Bucket, aliasBucket *bolt.Bucket, node *LightningNode) error {
var (
scratch [8]byte
b bytes.Buffer
)
nodePub := node.PubKey.SerializeCompressed()
if err := aliasBucket.Put(nodePub, []byte(node.Alias)); err != nil {
return err
}
updateUnix := uint64(node.LastUpdate.Unix())
byteOrder.PutUint64(scratch[:], updateUnix)
if _, err := b.Write(scratch[:]); err != nil {
return err
}
addrString := node.Address.String()
if err := wire.WriteVarString(&b, 0, addrString); err != nil {
return err
}
if _, err := b.Write(nodePub); err != nil {
return err
}
if err := binary.Write(&b, byteOrder, node.Color.R); err != nil {
return err
}
if err := binary.Write(&b, byteOrder, node.Color.G); err != nil {
return err
}
if err := binary.Write(&b, byteOrder, node.Color.B); err != nil {
return err
}
if err := wire.WriteVarString(&b, 0, node.Alias); err != nil {
return err
}
return nodeBucket.Put(nodePub, b.Bytes())
}
func fetchLightningNode(nodeBucket *bolt.Bucket,
nodePub []byte) (*LightningNode, error) {
nodeBytes := nodeBucket.Get(nodePub)
if nodeBytes == nil {
return nil, ErrGraphNodesNotFound
}
nodeReader := bytes.NewReader(nodeBytes)
return deserializeLightningNode(nodeReader)
}
func deserializeLightningNode(r io.Reader) (*LightningNode, error) {
node := &LightningNode{}
var scratch [8]byte
if _, err := r.Read(scratch[:]); err != nil {
return nil, err
}
unix := int64(byteOrder.Uint64(scratch[:]))
node.LastUpdate = time.Unix(unix, 0)
addrString, err := wire.ReadVarString(r, 0)
if err != nil {
return nil, err
}
node.Address, err = net.ResolveTCPAddr("tcp", addrString)
if err != nil {
return nil, err
}
var pub [33]byte
if _, err := r.Read(pub[:]); err != nil {
return nil, err
}
node.PubKey, err = btcec.ParsePubKey(pub[:], btcec.S256())
if err != nil {
return nil, err
}
if err := binary.Read(r, byteOrder, &node.Color.R); err != nil {
return nil, err
}
if err := binary.Read(r, byteOrder, &node.Color.G); err != nil {
return nil, err
}
if err := binary.Read(r, byteOrder, &node.Color.B); err != nil {
return nil, err
}
node.Alias, err = wire.ReadVarString(r, 0)
if err != nil {
return nil, err
}
return node, nil
}
func putChannelEdge(edges *bolt.Bucket, edge *ChannelEdge, from, to []byte) error {
var edgeKey [33 + 8]byte
copy(edgeKey[:], from)
byteOrder.PutUint64(edgeKey[33:], edge.ChannelID)
var b bytes.Buffer
if err := binary.Write(&b, byteOrder, edge.ChannelID); err != nil {
return err
}
if err := writeOutpoint(&b, &edge.ChannelPoint); err != nil {
return err
}
var scratch [8]byte
updateUnix := uint64(edge.LastUpdate.Unix())
byteOrder.PutUint64(scratch[:], updateUnix)
if _, err := b.Write(scratch[:]); err != nil {
return err
}
if err := binary.Write(&b, byteOrder, edge.Flags); err != nil {
return err
}
if err := binary.Write(&b, byteOrder, edge.Expiry); err != nil {
return err
}
if err := binary.Write(&b, byteOrder, uint64(edge.MinHTLC)); err != nil {
return err
}
if err := binary.Write(&b, byteOrder, uint64(edge.FeeBaseMSat)); err != nil {
return err
}
if err := binary.Write(&b, byteOrder, uint64(edge.FeeProportionalMillionths)); err != nil {
return err
}
if err := binary.Write(&b, byteOrder, uint64(edge.Capacity)); err != nil {
return err
}
if _, err := b.Write(to); err != nil {
return err
}
return edges.Put(edgeKey[:], b.Bytes()[:])
}
func fetchEdges(edgeIndex *bolt.Bucket, edges *bolt.Bucket, nodes *bolt.Bucket,
chanID []byte, db *DB) (*ChannelEdge, *ChannelEdge, error) {
edgeInfo := edgeIndex.Get(chanID)
if edgeIndex == nil {
return nil, nil, ErrEdgeNotFound
}
// The first node is contained within the first half of the
// edge information.
node1Pub := edgeInfo[:33]
edge1, err := fetchChannelEdge(edges, chanID, node1Pub, nodes)
if err != nil {
return nil, nil, err
}
edge1.db = db
edge1.Node.db = db
// Similarly, the second node is contained within the latter
// half of the edge information.
node2Pub := edgeInfo[33:]
edge2, err := fetchChannelEdge(edges, chanID, node2Pub, nodes)
if err != nil {
return nil, nil, err
}
edge2.db = db
edge2.Node.db = db
return edge1, edge2, nil
}
func fetchChannelEdge(edges *bolt.Bucket, chanID []byte,
nodePub []byte, nodes *bolt.Bucket) (*ChannelEdge, error) {
var edgeKey [33 + 8]byte
copy(edgeKey[:], nodePub)
copy(edgeKey[33:], chanID[:])
edgeBytes := edges.Get(edgeKey[:])
if edgeBytes == nil {
return nil, ErrEdgeNotFound
}
edgeReader := bytes.NewReader(edgeBytes)
return deserializeChannelEdge(edgeReader, nodes)
}
func deserializeChannelEdge(r io.Reader, nodes *bolt.Bucket) (*ChannelEdge, error) {
edge := &ChannelEdge{}
if err := binary.Read(r, byteOrder, &edge.ChannelID); err != nil {
return nil, err
}
edge.ChannelPoint = wire.OutPoint{}
if err := readOutpoint(r, &edge.ChannelPoint); err != nil {
return nil, err
}
var scratch [8]byte
if _, err := r.Read(scratch[:]); err != nil {
return nil, err
}
unix := int64(byteOrder.Uint64(scratch[:]))
edge.LastUpdate = time.Unix(unix, 0)
if err := binary.Read(r, byteOrder, &edge.Flags); err != nil {
return nil, err
}
if err := binary.Read(r, byteOrder, &edge.Expiry); err != nil {
return nil, err
}
var n uint64
if err := binary.Read(r, byteOrder, &n); err != nil {
return nil, err
}
edge.MinHTLC = btcutil.Amount(n)
if err := binary.Read(r, byteOrder, &n); err != nil {
return nil, err
}
edge.FeeBaseMSat = btcutil.Amount(n)
if err := binary.Read(r, byteOrder, &n); err != nil {
return nil, err
}
edge.FeeProportionalMillionths = btcutil.Amount(n)
if err := binary.Read(r, byteOrder, &n); err != nil {
return nil, err
}
edge.Capacity = btcutil.Amount(n)
var pub [33]byte
if _, err := r.Read(pub[:]); err != nil {
return nil, err
}
node, err := fetchLightningNode(nodes, pub[:])
if err != nil {
return nil, err
}
edge.Node = node
return edge, nil
}