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author | Janos Guljas <janos@resenje.org> | 2018-09-25 22:57:31 +0800 |
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committer | Janos Guljas <janos@resenje.org> | 2018-09-25 22:57:31 +0800 |
commit | 24349144b6c0642755569268bab56b9033743212 (patch) | |
tree | 9d9d2b6659fd8a56512dfc807aafe4b733165ae1 /p2p/enode/nodedb.go | |
parent | 7d56602391e155e2ce9ba7c261300a1804ab9972 (diff) | |
parent | d3441ebb563439bac0837d70591f92e2c6080303 (diff) | |
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Merge branch 'master' into max-stream-peer-servers
Diffstat (limited to 'p2p/enode/nodedb.go')
-rw-r--r-- | p2p/enode/nodedb.go | 349 |
1 files changed, 349 insertions, 0 deletions
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 <http://www.gnu.org/licenses/>. + +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() +} |