From 30cd5c18549f645002aedb4c00e5bab683cb0835 Mon Sep 17 00:00:00 2001 From: Felix Lange Date: Tue, 25 Sep 2018 00:59:00 +0200 Subject: all: new p2p node representation (#17643) Package p2p/enode provides a generalized representation of p2p nodes which can contain arbitrary information in key/value pairs. It is also the new home for the node database. The "v4" identity scheme is also moved here from p2p/enr to remove the dependency on Ethereum crypto from that package. Record signature handling is changed significantly. The identity scheme registry is removed and acceptable schemes must be passed to any method that needs identity. This means records must now be validated explicitly after decoding. The enode API is designed to make signature handling easy and safe: most APIs around the codebase work with enode.Node, which is a wrapper around a valid record. Going from enr.Record to enode.Node requires a valid signature. * p2p/discover: port to p2p/enode This ports the discovery code to the new node representation in p2p/enode. The wire protocol is unchanged, this can be considered a refactoring change. The Kademlia table can now deal with nodes using an arbitrary identity scheme. This requires a few incompatible API changes: - Table.Lookup is not available anymore. It used to take a public key as argument because v4 protocol requires one. Its replacement is LookupRandom. - Table.Resolve takes *enode.Node instead of NodeID. This is also for v4 protocol compatibility because nodes cannot be looked up by ID alone. - Types Node and NodeID are gone. Further commits in the series will be fixes all over the the codebase to deal with those removals. * p2p: port to p2p/enode and discovery changes This adapts package p2p to the changes in p2p/discover. All uses of discover.Node and discover.NodeID are replaced by their equivalents from p2p/enode. New API is added to retrieve the enode.Node instance of a peer. The behavior of Server.Self with discovery disabled is improved. It now tries much harder to report a working IP address, falling back to 127.0.0.1 if no suitable address can be determined through other means. These changes were needed for tests of other packages later in the series. * p2p/simulations, p2p/testing: port to p2p/enode No surprises here, mostly replacements of discover.Node, discover.NodeID with their new equivalents. The 'interesting' API changes are: - testing.ProtocolSession tracks complete nodes, not just their IDs. - adapters.NodeConfig has a new method to create a complete node. These changes were needed to make swarm tests work. Note that the NodeID change makes the code incompatible with old simulation snapshots. * whisper/whisperv5, whisper/whisperv6: port to p2p/enode This port was easy because whisper uses []byte for node IDs and URL strings in the API. * eth: port to p2p/enode Again, easy to port because eth uses strings for node IDs and doesn't care about node information in any way. * les: port to p2p/enode Apart from replacing discover.NodeID with enode.ID, most changes are in the server pool code. It now deals with complete nodes instead of (Pubkey, IP, Port) triples. The database format is unchanged for now, but we should probably change it to use the node database later. * node: port to p2p/enode This change simply replaces discover.Node and discover.NodeID with their new equivalents. * swarm/network: port to p2p/enode Swarm has its own node address representation, BzzAddr, containing both an overlay address (the hash of a secp256k1 public key) and an underlay address (enode:// URL). There are no changes to the BzzAddr format in this commit, but certain operations such as creating a BzzAddr from a node ID are now impossible because node IDs aren't public keys anymore. Most swarm-related changes in the series remove uses of NewAddrFromNodeID, replacing it with NewAddr which takes a complete node as argument. ToOverlayAddr is removed because we can just use the node ID directly. --- p2p/enode/nodedb.go | 349 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 349 insertions(+) create mode 100644 p2p/enode/nodedb.go (limited to 'p2p/enode/nodedb.go') diff --git a/p2p/enode/nodedb.go b/p2p/enode/nodedb.go new file mode 100644 index 000000000..a929b75d7 --- /dev/null +++ b/p2p/enode/nodedb.go @@ -0,0 +1,349 @@ +// Copyright 2015 The go-ethereum Authors +// This file is part of the go-ethereum library. +// +// The go-ethereum library is free software: you can redistribute it and/or modify +// it under the terms of the GNU Lesser General Public License as published by +// the Free Software Foundation, either version 3 of the License, or +// (at your option) any later version. +// +// The go-ethereum library is distributed in the hope that it will be useful, +// but WITHOUT ANY WARRANTY; without even the implied warranty of +// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +// GNU Lesser General Public License for more details. +// +// You should have received a copy of the GNU Lesser General Public License +// along with the go-ethereum library. If not, see . + +package enode + +import ( + "bytes" + "crypto/rand" + "encoding/binary" + "fmt" + "os" + "sync" + "time" + + "github.com/ethereum/go-ethereum/log" + "github.com/ethereum/go-ethereum/rlp" + "github.com/syndtr/goleveldb/leveldb" + "github.com/syndtr/goleveldb/leveldb/errors" + "github.com/syndtr/goleveldb/leveldb/iterator" + "github.com/syndtr/goleveldb/leveldb/opt" + "github.com/syndtr/goleveldb/leveldb/storage" + "github.com/syndtr/goleveldb/leveldb/util" +) + +var ( + nodeDBNilID = ID{} // Special node ID to use as a nil element. + nodeDBNodeExpiration = 24 * time.Hour // Time after which an unseen node should be dropped. + nodeDBCleanupCycle = time.Hour // Time period for running the expiration task. + nodeDBVersion = 6 +) + +// DB is the node database, storing previously seen nodes and any collected metadata about +// them for QoS purposes. +type DB struct { + lvl *leveldb.DB // Interface to the database itself + runner sync.Once // Ensures we can start at most one expirer + quit chan struct{} // Channel to signal the expiring thread to stop +} + +// Schema layout for the node database +var ( + nodeDBVersionKey = []byte("version") // Version of the database to flush if changes + nodeDBItemPrefix = []byte("n:") // Identifier to prefix node entries with + + nodeDBDiscoverRoot = ":discover" + nodeDBDiscoverPing = nodeDBDiscoverRoot + ":lastping" + nodeDBDiscoverPong = nodeDBDiscoverRoot + ":lastpong" + nodeDBDiscoverFindFails = nodeDBDiscoverRoot + ":findfail" +) + +// OpenDB opens a node database for storing and retrieving infos about known peers in the +// network. If no path is given an in-memory, temporary database is constructed. +func OpenDB(path string) (*DB, error) { + if path == "" { + return newMemoryDB() + } + return newPersistentDB(path) +} + +// newMemoryNodeDB creates a new in-memory node database without a persistent backend. +func newMemoryDB() (*DB, error) { + db, err := leveldb.Open(storage.NewMemStorage(), nil) + if err != nil { + return nil, err + } + return &DB{lvl: db, quit: make(chan struct{})}, nil +} + +// newPersistentNodeDB creates/opens a leveldb backed persistent node database, +// also flushing its contents in case of a version mismatch. +func newPersistentDB(path string) (*DB, error) { + opts := &opt.Options{OpenFilesCacheCapacity: 5} + db, err := leveldb.OpenFile(path, opts) + if _, iscorrupted := err.(*errors.ErrCorrupted); iscorrupted { + db, err = leveldb.RecoverFile(path, nil) + } + if err != nil { + return nil, err + } + // The nodes contained in the cache correspond to a certain protocol version. + // Flush all nodes if the version doesn't match. + currentVer := make([]byte, binary.MaxVarintLen64) + currentVer = currentVer[:binary.PutVarint(currentVer, int64(nodeDBVersion))] + + blob, err := db.Get(nodeDBVersionKey, nil) + switch err { + case leveldb.ErrNotFound: + // Version not found (i.e. empty cache), insert it + if err := db.Put(nodeDBVersionKey, currentVer, nil); err != nil { + db.Close() + return nil, err + } + + case nil: + // Version present, flush if different + if !bytes.Equal(blob, currentVer) { + db.Close() + if err = os.RemoveAll(path); err != nil { + return nil, err + } + return newPersistentDB(path) + } + } + return &DB{lvl: db, quit: make(chan struct{})}, nil +} + +// makeKey generates the leveldb key-blob from a node id and its particular +// field of interest. +func makeKey(id ID, field string) []byte { + if bytes.Equal(id[:], nodeDBNilID[:]) { + return []byte(field) + } + return append(nodeDBItemPrefix, append(id[:], field...)...) +} + +// splitKey tries to split a database key into a node id and a field part. +func splitKey(key []byte) (id ID, field string) { + // If the key is not of a node, return it plainly + if !bytes.HasPrefix(key, nodeDBItemPrefix) { + return ID{}, string(key) + } + // Otherwise split the id and field + item := key[len(nodeDBItemPrefix):] + copy(id[:], item[:len(id)]) + field = string(item[len(id):]) + + return id, field +} + +// fetchInt64 retrieves an integer instance associated with a particular +// database key. +func (db *DB) fetchInt64(key []byte) int64 { + blob, err := db.lvl.Get(key, nil) + if err != nil { + return 0 + } + val, read := binary.Varint(blob) + if read <= 0 { + return 0 + } + return val +} + +// storeInt64 update a specific database entry to the current time instance as a +// unix timestamp. +func (db *DB) storeInt64(key []byte, n int64) error { + blob := make([]byte, binary.MaxVarintLen64) + blob = blob[:binary.PutVarint(blob, n)] + + return db.lvl.Put(key, blob, nil) +} + +// Node retrieves a node with a given id from the database. +func (db *DB) Node(id ID) *Node { + blob, err := db.lvl.Get(makeKey(id, nodeDBDiscoverRoot), nil) + if err != nil { + return nil + } + return mustDecodeNode(id[:], blob) +} + +func mustDecodeNode(id, data []byte) *Node { + node := new(Node) + if err := rlp.DecodeBytes(data, &node.r); err != nil { + panic(fmt.Errorf("p2p/enode: can't decode node %x in DB: %v", id, err)) + } + // Restore node id cache. + copy(node.id[:], id) + return node +} + +// UpdateNode inserts - potentially overwriting - a node into the peer database. +func (db *DB) UpdateNode(node *Node) error { + blob, err := rlp.EncodeToBytes(&node.r) + if err != nil { + return err + } + return db.lvl.Put(makeKey(node.ID(), nodeDBDiscoverRoot), blob, nil) +} + +// DeleteNode deletes all information/keys associated with a node. +func (db *DB) DeleteNode(id ID) error { + deleter := db.lvl.NewIterator(util.BytesPrefix(makeKey(id, "")), nil) + for deleter.Next() { + if err := db.lvl.Delete(deleter.Key(), nil); err != nil { + return err + } + } + return nil +} + +// ensureExpirer is a small helper method ensuring that the data expiration +// mechanism is running. If the expiration goroutine is already running, this +// method simply returns. +// +// The goal is to start the data evacuation only after the network successfully +// bootstrapped itself (to prevent dumping potentially useful seed nodes). Since +// it would require significant overhead to exactly trace the first successful +// convergence, it's simpler to "ensure" the correct state when an appropriate +// condition occurs (i.e. a successful bonding), and discard further events. +func (db *DB) ensureExpirer() { + db.runner.Do(func() { go db.expirer() }) +} + +// expirer should be started in a go routine, and is responsible for looping ad +// infinitum and dropping stale data from the database. +func (db *DB) expirer() { + tick := time.NewTicker(nodeDBCleanupCycle) + defer tick.Stop() + for { + select { + case <-tick.C: + if err := db.expireNodes(); err != nil { + log.Error("Failed to expire nodedb items", "err", err) + } + case <-db.quit: + return + } + } +} + +// expireNodes iterates over the database and deletes all nodes that have not +// been seen (i.e. received a pong from) for some allotted time. +func (db *DB) expireNodes() error { + threshold := time.Now().Add(-nodeDBNodeExpiration) + + // Find discovered nodes that are older than the allowance + it := db.lvl.NewIterator(nil, nil) + defer it.Release() + + for it.Next() { + // Skip the item if not a discovery node + id, field := splitKey(it.Key()) + if field != nodeDBDiscoverRoot { + continue + } + // Skip the node if not expired yet (and not self) + if seen := db.LastPongReceived(id); seen.After(threshold) { + continue + } + // Otherwise delete all associated information + db.DeleteNode(id) + } + return nil +} + +// LastPingReceived retrieves the time of the last ping packet received from +// a remote node. +func (db *DB) LastPingReceived(id ID) time.Time { + return time.Unix(db.fetchInt64(makeKey(id, nodeDBDiscoverPing)), 0) +} + +// UpdateLastPingReceived updates the last time we tried contacting a remote node. +func (db *DB) UpdateLastPingReceived(id ID, instance time.Time) error { + return db.storeInt64(makeKey(id, nodeDBDiscoverPing), instance.Unix()) +} + +// LastPongReceived retrieves the time of the last successful pong from remote node. +func (db *DB) LastPongReceived(id ID) time.Time { + // Launch expirer + db.ensureExpirer() + return time.Unix(db.fetchInt64(makeKey(id, nodeDBDiscoverPong)), 0) +} + +// UpdateLastPongReceived updates the last pong time of a node. +func (db *DB) UpdateLastPongReceived(id ID, instance time.Time) error { + return db.storeInt64(makeKey(id, nodeDBDiscoverPong), instance.Unix()) +} + +// FindFails retrieves the number of findnode failures since bonding. +func (db *DB) FindFails(id ID) int { + return int(db.fetchInt64(makeKey(id, nodeDBDiscoverFindFails))) +} + +// UpdateFindFails updates the number of findnode failures since bonding. +func (db *DB) UpdateFindFails(id ID, fails int) error { + return db.storeInt64(makeKey(id, nodeDBDiscoverFindFails), int64(fails)) +} + +// QuerySeeds retrieves random nodes to be used as potential seed nodes +// for bootstrapping. +func (db *DB) QuerySeeds(n int, maxAge time.Duration) []*Node { + var ( + now = time.Now() + nodes = make([]*Node, 0, n) + it = db.lvl.NewIterator(nil, nil) + id ID + ) + defer it.Release() + +seek: + for seeks := 0; len(nodes) < n && seeks < n*5; seeks++ { + // Seek to a random entry. The first byte is incremented by a + // random amount each time in order to increase the likelihood + // of hitting all existing nodes in very small databases. + ctr := id[0] + rand.Read(id[:]) + id[0] = ctr + id[0]%16 + it.Seek(makeKey(id, nodeDBDiscoverRoot)) + + n := nextNode(it) + if n == nil { + id[0] = 0 + continue seek // iterator exhausted + } + if now.Sub(db.LastPongReceived(n.ID())) > maxAge { + continue seek + } + for i := range nodes { + if nodes[i].ID() == n.ID() { + continue seek // duplicate + } + } + nodes = append(nodes, n) + } + return nodes +} + +// reads the next node record from the iterator, skipping over other +// database entries. +func nextNode(it iterator.Iterator) *Node { + for end := false; !end; end = !it.Next() { + id, field := splitKey(it.Key()) + if field != nodeDBDiscoverRoot { + continue + } + return mustDecodeNode(id[:], it.Value()) + } + return nil +} + +// close flushes and closes the database files. +func (db *DB) Close() { + close(db.quit) + db.lvl.Close() +} -- cgit v1.2.3