6f607de5d5
This PR adds enode.LocalNode and integrates it into the p2p subsystem. This new object is the keeper of the local node record. For now, a new version of the record is produced every time the client restarts. We'll make it smarter to avoid that in the future. There are a couple of other changes in this commit: discovery now waits for all of its goroutines at shutdown and the p2p server now closes the node database after discovery has shut down. This fixes a leveldb crash in tests. p2p server startup is faster because it doesn't need to wait for the external IP query anymore.
131 lines
4.0 KiB
Go
131 lines
4.0 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 netutil
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import (
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"time"
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"github.com/ethereum/go-ethereum/common/mclock"
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)
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// IPTracker predicts the external endpoint, i.e. IP address and port, of the local host
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// based on statements made by other hosts.
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type IPTracker struct {
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window time.Duration
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contactWindow time.Duration
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minStatements int
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clock mclock.Clock
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statements map[string]ipStatement
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contact map[string]mclock.AbsTime
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lastStatementGC mclock.AbsTime
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lastContactGC mclock.AbsTime
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}
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type ipStatement struct {
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endpoint string
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time mclock.AbsTime
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}
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// NewIPTracker creates an IP tracker.
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//
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// The window parameters configure the amount of past network events which are kept. The
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// minStatements parameter enforces a minimum number of statements which must be recorded
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// before any prediction is made. Higher values for these parameters decrease 'flapping' of
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// predictions as network conditions change. Window duration values should typically be in
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// the range of minutes.
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func NewIPTracker(window, contactWindow time.Duration, minStatements int) *IPTracker {
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return &IPTracker{
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window: window,
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contactWindow: contactWindow,
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statements: make(map[string]ipStatement),
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minStatements: minStatements,
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contact: make(map[string]mclock.AbsTime),
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clock: mclock.System{},
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}
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}
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// PredictFullConeNAT checks whether the local host is behind full cone NAT. It predicts by
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// checking whether any statement has been received from a node we didn't contact before
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// the statement was made.
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func (it *IPTracker) PredictFullConeNAT() bool {
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now := it.clock.Now()
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it.gcContact(now)
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it.gcStatements(now)
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for host, st := range it.statements {
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if c, ok := it.contact[host]; !ok || c > st.time {
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return true
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}
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}
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return false
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}
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// PredictEndpoint returns the current prediction of the external endpoint.
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func (it *IPTracker) PredictEndpoint() string {
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it.gcStatements(it.clock.Now())
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// The current strategy is simple: find the endpoint with most statements.
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counts := make(map[string]int)
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maxcount, max := 0, ""
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for _, s := range it.statements {
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c := counts[s.endpoint] + 1
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counts[s.endpoint] = c
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if c > maxcount && c >= it.minStatements {
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maxcount, max = c, s.endpoint
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}
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}
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return max
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}
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// AddStatement records that a certain host thinks our external endpoint is the one given.
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func (it *IPTracker) AddStatement(host, endpoint string) {
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now := it.clock.Now()
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it.statements[host] = ipStatement{endpoint, now}
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if time.Duration(now-it.lastStatementGC) >= it.window {
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it.gcStatements(now)
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}
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}
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// AddContact records that a packet containing our endpoint information has been sent to a
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// certain host.
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func (it *IPTracker) AddContact(host string) {
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now := it.clock.Now()
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it.contact[host] = now
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if time.Duration(now-it.lastContactGC) >= it.contactWindow {
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it.gcContact(now)
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}
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}
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func (it *IPTracker) gcStatements(now mclock.AbsTime) {
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it.lastStatementGC = now
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cutoff := now.Add(-it.window)
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for host, s := range it.statements {
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if s.time < cutoff {
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delete(it.statements, host)
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}
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}
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}
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func (it *IPTracker) gcContact(now mclock.AbsTime) {
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it.lastContactGC = now
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cutoff := now.Add(-it.contactWindow)
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for host, ct := range it.contact {
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if ct < cutoff {
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delete(it.contact, host)
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}
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}
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}
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