333 lines
8.7 KiB
Go
333 lines
8.7 KiB
Go
// Copyright 2018 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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package enode
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import (
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"crypto/ecdsa"
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"fmt"
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"net"
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"reflect"
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"strconv"
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"sync"
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"sync/atomic"
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"time"
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"github.com/ethereum/go-ethereum/log"
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"github.com/ethereum/go-ethereum/p2p/enr"
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"github.com/ethereum/go-ethereum/p2p/netutil"
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)
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const (
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// IP tracker configuration
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iptrackMinStatements = 10
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iptrackWindow = 5 * time.Minute
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iptrackContactWindow = 10 * time.Minute
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// time needed to wait between two updates to the local ENR
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recordUpdateThrottle = time.Millisecond
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)
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// LocalNode produces the signed node record of a local node, i.e. a node run in the
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// current process. Setting ENR entries via the Set method updates the record. A new version
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// of the record is signed on demand when the Node method is called.
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type LocalNode struct {
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cur atomic.Value // holds a non-nil node pointer while the record is up-to-date
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id ID
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key *ecdsa.PrivateKey
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db *DB
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// everything below is protected by a lock
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mu sync.RWMutex
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seq uint64
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update time.Time // timestamp when the record was last updated
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entries map[string]enr.Entry
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endpoint4 lnEndpoint
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endpoint6 lnEndpoint
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}
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type lnEndpoint struct {
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track *netutil.IPTracker
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staticIP, fallbackIP net.IP
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fallbackUDP uint16 // port
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}
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// NewLocalNode creates a local node.
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func NewLocalNode(db *DB, key *ecdsa.PrivateKey) *LocalNode {
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ln := &LocalNode{
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id: PubkeyToIDV4(&key.PublicKey),
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db: db,
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key: key,
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entries: make(map[string]enr.Entry),
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endpoint4: lnEndpoint{
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track: netutil.NewIPTracker(iptrackWindow, iptrackContactWindow, iptrackMinStatements),
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},
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endpoint6: lnEndpoint{
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track: netutil.NewIPTracker(iptrackWindow, iptrackContactWindow, iptrackMinStatements),
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},
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}
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ln.seq = db.localSeq(ln.id)
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ln.update = time.Now()
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ln.cur.Store((*Node)(nil))
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return ln
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}
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// Database returns the node database associated with the local node.
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func (ln *LocalNode) Database() *DB {
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return ln.db
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}
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// Node returns the current version of the local node record.
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func (ln *LocalNode) Node() *Node {
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// If we have a valid record, return that
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n := ln.cur.Load().(*Node)
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if n != nil {
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return n
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}
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// Record was invalidated, sign a new copy.
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ln.mu.Lock()
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defer ln.mu.Unlock()
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// Double check the current record, since multiple goroutines might be waiting
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// on the write mutex.
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if n = ln.cur.Load().(*Node); n != nil {
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return n
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}
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// The initial sequence number is the current timestamp in milliseconds. To ensure
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// that the initial sequence number will always be higher than any previous sequence
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// number (assuming the clock is correct), we want to avoid updating the record faster
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// than once per ms. So we need to sleep here until the next possible update time has
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// arrived.
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lastChange := time.Since(ln.update)
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if lastChange < recordUpdateThrottle {
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time.Sleep(recordUpdateThrottle - lastChange)
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}
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ln.sign()
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ln.update = time.Now()
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return ln.cur.Load().(*Node)
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}
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// Seq returns the current sequence number of the local node record.
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func (ln *LocalNode) Seq() uint64 {
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ln.mu.Lock()
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defer ln.mu.Unlock()
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return ln.seq
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}
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// ID returns the local node ID.
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func (ln *LocalNode) ID() ID {
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return ln.id
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}
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// Set puts the given entry into the local record, overwriting any existing value.
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// Use Set*IP and SetFallbackUDP to set IP addresses and UDP port, otherwise they'll
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// be overwritten by the endpoint predictor.
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//
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// Since node record updates are throttled to one per second, Set is asynchronous.
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// Any update will be queued up and published when at least one second passes from
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// the last change.
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func (ln *LocalNode) Set(e enr.Entry) {
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ln.mu.Lock()
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defer ln.mu.Unlock()
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ln.set(e)
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}
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func (ln *LocalNode) set(e enr.Entry) {
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val, exists := ln.entries[e.ENRKey()]
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if !exists || !reflect.DeepEqual(val, e) {
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ln.entries[e.ENRKey()] = e
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ln.invalidate()
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}
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}
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// Delete removes the given entry from the local record.
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func (ln *LocalNode) Delete(e enr.Entry) {
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ln.mu.Lock()
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defer ln.mu.Unlock()
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ln.delete(e)
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}
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func (ln *LocalNode) delete(e enr.Entry) {
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_, exists := ln.entries[e.ENRKey()]
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if exists {
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delete(ln.entries, e.ENRKey())
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ln.invalidate()
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}
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}
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func (ln *LocalNode) endpointForIP(ip net.IP) *lnEndpoint {
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if ip.To4() != nil {
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return &ln.endpoint4
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}
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return &ln.endpoint6
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}
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// SetStaticIP sets the local IP to the given one unconditionally.
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// This disables endpoint prediction.
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func (ln *LocalNode) SetStaticIP(ip net.IP) {
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ln.mu.Lock()
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defer ln.mu.Unlock()
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ln.endpointForIP(ip).staticIP = ip
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ln.updateEndpoints()
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}
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// SetFallbackIP sets the last-resort IP address. This address is used
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// if no endpoint prediction can be made and no static IP is set.
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func (ln *LocalNode) SetFallbackIP(ip net.IP) {
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ln.mu.Lock()
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defer ln.mu.Unlock()
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ln.endpointForIP(ip).fallbackIP = ip
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ln.updateEndpoints()
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}
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// SetFallbackUDP sets the last-resort UDP-on-IPv4 port. This port is used
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// if no endpoint prediction can be made.
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func (ln *LocalNode) SetFallbackUDP(port int) {
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ln.mu.Lock()
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defer ln.mu.Unlock()
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ln.endpoint4.fallbackUDP = uint16(port)
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ln.endpoint6.fallbackUDP = uint16(port)
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ln.updateEndpoints()
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}
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// UDPEndpointStatement should be called whenever a statement about the local node's
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// UDP endpoint is received. It feeds the local endpoint predictor.
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func (ln *LocalNode) UDPEndpointStatement(fromaddr, endpoint *net.UDPAddr) {
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ln.mu.Lock()
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defer ln.mu.Unlock()
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ln.endpointForIP(endpoint.IP).track.AddStatement(fromaddr.String(), endpoint.String())
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ln.updateEndpoints()
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}
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// UDPContact should be called whenever the local node has announced itself to another node
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// via UDP. It feeds the local endpoint predictor.
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func (ln *LocalNode) UDPContact(toaddr *net.UDPAddr) {
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ln.mu.Lock()
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defer ln.mu.Unlock()
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ln.endpointForIP(toaddr.IP).track.AddContact(toaddr.String())
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ln.updateEndpoints()
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}
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// updateEndpoints updates the record with predicted endpoints.
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func (ln *LocalNode) updateEndpoints() {
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ip4, udp4 := ln.endpoint4.get()
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ip6, udp6 := ln.endpoint6.get()
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if ip4 != nil && !ip4.IsUnspecified() {
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ln.set(enr.IPv4(ip4))
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} else {
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ln.delete(enr.IPv4{})
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}
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if ip6 != nil && !ip6.IsUnspecified() {
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ln.set(enr.IPv6(ip6))
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} else {
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ln.delete(enr.IPv6{})
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}
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if udp4 != 0 {
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ln.set(enr.UDP(udp4))
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} else {
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ln.delete(enr.UDP(0))
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}
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if udp6 != 0 && udp6 != udp4 {
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ln.set(enr.UDP6(udp6))
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} else {
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ln.delete(enr.UDP6(0))
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}
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}
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// get returns the endpoint with highest precedence.
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func (e *lnEndpoint) get() (newIP net.IP, newPort uint16) {
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newPort = e.fallbackUDP
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if e.fallbackIP != nil {
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newIP = e.fallbackIP
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}
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if e.staticIP != nil {
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newIP = e.staticIP
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} else if ip, port := predictAddr(e.track); ip != nil {
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newIP = ip
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newPort = port
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}
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return newIP, newPort
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}
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// predictAddr wraps IPTracker.PredictEndpoint, converting from its string-based
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// endpoint representation to IP and port types.
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func predictAddr(t *netutil.IPTracker) (net.IP, uint16) {
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ep := t.PredictEndpoint()
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if ep == "" {
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return nil, 0
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}
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ipString, portString, _ := net.SplitHostPort(ep)
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ip := net.ParseIP(ipString)
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port, err := strconv.ParseUint(portString, 10, 16)
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if err != nil {
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return nil, 0
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}
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return ip, uint16(port)
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}
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func (ln *LocalNode) invalidate() {
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ln.cur.Store((*Node)(nil))
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}
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func (ln *LocalNode) sign() {
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if n := ln.cur.Load().(*Node); n != nil {
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return // no changes
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}
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var r enr.Record
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for _, e := range ln.entries {
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r.Set(e)
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}
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ln.bumpSeq()
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r.SetSeq(ln.seq)
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if err := SignV4(&r, ln.key); err != nil {
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panic(fmt.Errorf("enode: can't sign record: %v", err))
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}
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n, err := New(ValidSchemes, &r)
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if err != nil {
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panic(fmt.Errorf("enode: can't verify local record: %v", err))
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}
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ln.cur.Store(n)
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log.Info("New local node record", "seq", ln.seq, "id", n.ID(), "ip", n.IP(), "udp", n.UDP(), "tcp", n.TCP())
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}
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func (ln *LocalNode) bumpSeq() {
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ln.seq++
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ln.db.storeLocalSeq(ln.id, ln.seq)
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}
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// nowMilliseconds gives the current timestamp at millisecond precision.
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func nowMilliseconds() uint64 {
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ns := time.Now().UnixNano()
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if ns < 0 {
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return 0
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}
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return uint64(ns / 1000 / 1000)
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}
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