go-ethereum/p2p/enode/localnode.go

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// Copyright 2018 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 (
"crypto/ecdsa"
"fmt"
"net"
"reflect"
"strconv"
"sync"
"sync/atomic"
"time"
"github.com/ethereum/go-ethereum/log"
"github.com/ethereum/go-ethereum/p2p/enr"
"github.com/ethereum/go-ethereum/p2p/netutil"
)
const (
// IP tracker configuration
iptrackMinStatements = 10
iptrackWindow = 5 * time.Minute
iptrackContactWindow = 10 * time.Minute
// time needed to wait between two updates to the local ENR
recordUpdateThrottle = time.Millisecond
)
// LocalNode produces the signed node record of a local node, i.e. a node run in the
// current process. Setting ENR entries via the Set method updates the record. A new version
// of the record is signed on demand when the Node method is called.
type LocalNode struct {
cur atomic.Value // holds a non-nil node pointer while the record is up-to-date
id ID
key *ecdsa.PrivateKey
db *DB
// everything below is protected by a lock
mu sync.RWMutex
seq uint64
update time.Time // timestamp when the record was last updated
entries map[string]enr.Entry
endpoint4 lnEndpoint
endpoint6 lnEndpoint
}
type lnEndpoint struct {
track *netutil.IPTracker
staticIP, fallbackIP net.IP
fallbackUDP uint16 // port
}
// NewLocalNode creates a local node.
func NewLocalNode(db *DB, key *ecdsa.PrivateKey) *LocalNode {
ln := &LocalNode{
id: PubkeyToIDV4(&key.PublicKey),
db: db,
key: key,
entries: make(map[string]enr.Entry),
endpoint4: lnEndpoint{
track: netutil.NewIPTracker(iptrackWindow, iptrackContactWindow, iptrackMinStatements),
},
endpoint6: lnEndpoint{
track: netutil.NewIPTracker(iptrackWindow, iptrackContactWindow, iptrackMinStatements),
},
}
ln.seq = db.localSeq(ln.id)
ln.update = time.Now()
ln.cur.Store((*Node)(nil))
return ln
}
// Database returns the node database associated with the local node.
func (ln *LocalNode) Database() *DB {
return ln.db
}
// Node returns the current version of the local node record.
func (ln *LocalNode) Node() *Node {
// If we have a valid record, return that
n := ln.cur.Load().(*Node)
if n != nil {
return n
}
// Record was invalidated, sign a new copy.
ln.mu.Lock()
defer ln.mu.Unlock()
// Double check the current record, since multiple goroutines might be waiting
// on the write mutex.
if n = ln.cur.Load().(*Node); n != nil {
return n
}
// The initial sequence number is the current timestamp in milliseconds. To ensure
// that the initial sequence number will always be higher than any previous sequence
// number (assuming the clock is correct), we want to avoid updating the record faster
// than once per ms. So we need to sleep here until the next possible update time has
// arrived.
lastChange := time.Since(ln.update)
if lastChange < recordUpdateThrottle {
time.Sleep(recordUpdateThrottle - lastChange)
}
ln.sign()
ln.update = time.Now()
return ln.cur.Load().(*Node)
}
// Seq returns the current sequence number of the local node record.
func (ln *LocalNode) Seq() uint64 {
ln.mu.Lock()
defer ln.mu.Unlock()
return ln.seq
}
// ID returns the local node ID.
func (ln *LocalNode) ID() ID {
return ln.id
}
// Set puts the given entry into the local record, overwriting any existing value.
// Use Set*IP and SetFallbackUDP to set IP addresses and UDP port, otherwise they'll
// be overwritten by the endpoint predictor.
//
// Since node record updates are throttled to one per second, Set is asynchronous.
// Any update will be queued up and published when at least one second passes from
// the last change.
func (ln *LocalNode) Set(e enr.Entry) {
ln.mu.Lock()
defer ln.mu.Unlock()
ln.set(e)
}
func (ln *LocalNode) set(e enr.Entry) {
val, exists := ln.entries[e.ENRKey()]
if !exists || !reflect.DeepEqual(val, e) {
ln.entries[e.ENRKey()] = e
ln.invalidate()
}
}
// Delete removes the given entry from the local record.
func (ln *LocalNode) Delete(e enr.Entry) {
ln.mu.Lock()
defer ln.mu.Unlock()
ln.delete(e)
}
func (ln *LocalNode) delete(e enr.Entry) {
_, exists := ln.entries[e.ENRKey()]
if exists {
delete(ln.entries, e.ENRKey())
ln.invalidate()
}
}
func (ln *LocalNode) endpointForIP(ip net.IP) *lnEndpoint {
if ip.To4() != nil {
return &ln.endpoint4
}
return &ln.endpoint6
}
// SetStaticIP sets the local IP to the given one unconditionally.
// This disables endpoint prediction.
func (ln *LocalNode) SetStaticIP(ip net.IP) {
ln.mu.Lock()
defer ln.mu.Unlock()
ln.endpointForIP(ip).staticIP = ip
ln.updateEndpoints()
}
// SetFallbackIP sets the last-resort IP address. This address is used
// if no endpoint prediction can be made and no static IP is set.
func (ln *LocalNode) SetFallbackIP(ip net.IP) {
ln.mu.Lock()
defer ln.mu.Unlock()
ln.endpointForIP(ip).fallbackIP = ip
ln.updateEndpoints()
}
// SetFallbackUDP sets the last-resort UDP-on-IPv4 port. This port is used
// if no endpoint prediction can be made.
func (ln *LocalNode) SetFallbackUDP(port int) {
ln.mu.Lock()
defer ln.mu.Unlock()
ln.endpoint4.fallbackUDP = uint16(port)
ln.endpoint6.fallbackUDP = uint16(port)
ln.updateEndpoints()
}
// UDPEndpointStatement should be called whenever a statement about the local node's
// UDP endpoint is received. It feeds the local endpoint predictor.
func (ln *LocalNode) UDPEndpointStatement(fromaddr, endpoint *net.UDPAddr) {
ln.mu.Lock()
defer ln.mu.Unlock()
ln.endpointForIP(endpoint.IP).track.AddStatement(fromaddr.String(), endpoint.String())
ln.updateEndpoints()
}
// UDPContact should be called whenever the local node has announced itself to another node
// via UDP. It feeds the local endpoint predictor.
func (ln *LocalNode) UDPContact(toaddr *net.UDPAddr) {
ln.mu.Lock()
defer ln.mu.Unlock()
ln.endpointForIP(toaddr.IP).track.AddContact(toaddr.String())
ln.updateEndpoints()
}
// updateEndpoints updates the record with predicted endpoints.
func (ln *LocalNode) updateEndpoints() {
ip4, udp4 := ln.endpoint4.get()
ip6, udp6 := ln.endpoint6.get()
if ip4 != nil && !ip4.IsUnspecified() {
ln.set(enr.IPv4(ip4))
} else {
ln.delete(enr.IPv4{})
}
if ip6 != nil && !ip6.IsUnspecified() {
ln.set(enr.IPv6(ip6))
} else {
ln.delete(enr.IPv6{})
}
if udp4 != 0 {
ln.set(enr.UDP(udp4))
} else {
ln.delete(enr.UDP(0))
}
if udp6 != 0 && udp6 != udp4 {
ln.set(enr.UDP6(udp6))
} else {
ln.delete(enr.UDP6(0))
}
}
// get returns the endpoint with highest precedence.
func (e *lnEndpoint) get() (newIP net.IP, newPort uint16) {
newPort = e.fallbackUDP
if e.fallbackIP != nil {
newIP = e.fallbackIP
}
if e.staticIP != nil {
newIP = e.staticIP
} else if ip, port := predictAddr(e.track); ip != nil {
newIP = ip
newPort = port
}
return newIP, newPort
}
// predictAddr wraps IPTracker.PredictEndpoint, converting from its string-based
// endpoint representation to IP and port types.
func predictAddr(t *netutil.IPTracker) (net.IP, uint16) {
ep := t.PredictEndpoint()
if ep == "" {
return nil, 0
}
ipString, portString, _ := net.SplitHostPort(ep)
ip := net.ParseIP(ipString)
port, err := strconv.ParseUint(portString, 10, 16)
if err != nil {
return nil, 0
}
return ip, uint16(port)
}
func (ln *LocalNode) invalidate() {
ln.cur.Store((*Node)(nil))
}
func (ln *LocalNode) sign() {
if n := ln.cur.Load().(*Node); n != nil {
return // no changes
}
var r enr.Record
for _, e := range ln.entries {
r.Set(e)
}
ln.bumpSeq()
r.SetSeq(ln.seq)
if err := SignV4(&r, ln.key); err != nil {
panic(fmt.Errorf("enode: can't sign record: %v", err))
}
n, err := New(ValidSchemes, &r)
if err != nil {
panic(fmt.Errorf("enode: can't verify local record: %v", err))
}
ln.cur.Store(n)
log.Info("New local node record", "seq", ln.seq, "id", n.ID(), "ip", n.IP(), "udp", n.UDP(), "tcp", n.TCP())
}
func (ln *LocalNode) bumpSeq() {
ln.seq++
ln.db.storeLocalSeq(ln.id, ln.seq)
}
// nowMilliseconds gives the current timestamp at millisecond precision.
func nowMilliseconds() uint64 {
ns := time.Now().UnixNano()
if ns < 0 {
return 0
}
return uint64(ns / 1000 / 1000)
}