131 lines
4.0 KiB
Go
131 lines
4.0 KiB
Go
// 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 netutil
|
|
|
|
import (
|
|
"time"
|
|
|
|
"github.com/ethereum/go-ethereum/common/mclock"
|
|
)
|
|
|
|
// IPTracker predicts the external endpoint, i.e. IP address and port, of the local host
|
|
// based on statements made by other hosts.
|
|
type IPTracker struct {
|
|
window time.Duration
|
|
contactWindow time.Duration
|
|
minStatements int
|
|
clock mclock.Clock
|
|
statements map[string]ipStatement
|
|
contact map[string]mclock.AbsTime
|
|
lastStatementGC mclock.AbsTime
|
|
lastContactGC mclock.AbsTime
|
|
}
|
|
|
|
type ipStatement struct {
|
|
endpoint string
|
|
time mclock.AbsTime
|
|
}
|
|
|
|
// NewIPTracker creates an IP tracker.
|
|
//
|
|
// The window parameters configure the amount of past network events which are kept. The
|
|
// minStatements parameter enforces a minimum number of statements which must be recorded
|
|
// before any prediction is made. Higher values for these parameters decrease 'flapping' of
|
|
// predictions as network conditions change. Window duration values should typically be in
|
|
// the range of minutes.
|
|
func NewIPTracker(window, contactWindow time.Duration, minStatements int) *IPTracker {
|
|
return &IPTracker{
|
|
window: window,
|
|
contactWindow: contactWindow,
|
|
statements: make(map[string]ipStatement),
|
|
minStatements: minStatements,
|
|
contact: make(map[string]mclock.AbsTime),
|
|
clock: mclock.System{},
|
|
}
|
|
}
|
|
|
|
// PredictFullConeNAT checks whether the local host is behind full cone NAT. It predicts by
|
|
// checking whether any statement has been received from a node we didn't contact before
|
|
// the statement was made.
|
|
func (it *IPTracker) PredictFullConeNAT() bool {
|
|
now := it.clock.Now()
|
|
it.gcContact(now)
|
|
it.gcStatements(now)
|
|
for host, st := range it.statements {
|
|
if c, ok := it.contact[host]; !ok || c > st.time {
|
|
return true
|
|
}
|
|
}
|
|
return false
|
|
}
|
|
|
|
// PredictEndpoint returns the current prediction of the external endpoint.
|
|
func (it *IPTracker) PredictEndpoint() string {
|
|
it.gcStatements(it.clock.Now())
|
|
|
|
// The current strategy is simple: find the endpoint with most statements.
|
|
counts := make(map[string]int, len(it.statements))
|
|
maxcount, max := 0, ""
|
|
for _, s := range it.statements {
|
|
c := counts[s.endpoint] + 1
|
|
counts[s.endpoint] = c
|
|
if c > maxcount && c >= it.minStatements {
|
|
maxcount, max = c, s.endpoint
|
|
}
|
|
}
|
|
return max
|
|
}
|
|
|
|
// AddStatement records that a certain host thinks our external endpoint is the one given.
|
|
func (it *IPTracker) AddStatement(host, endpoint string) {
|
|
now := it.clock.Now()
|
|
it.statements[host] = ipStatement{endpoint, now}
|
|
if time.Duration(now-it.lastStatementGC) >= it.window {
|
|
it.gcStatements(now)
|
|
}
|
|
}
|
|
|
|
// AddContact records that a packet containing our endpoint information has been sent to a
|
|
// certain host.
|
|
func (it *IPTracker) AddContact(host string) {
|
|
now := it.clock.Now()
|
|
it.contact[host] = now
|
|
if time.Duration(now-it.lastContactGC) >= it.contactWindow {
|
|
it.gcContact(now)
|
|
}
|
|
}
|
|
|
|
func (it *IPTracker) gcStatements(now mclock.AbsTime) {
|
|
it.lastStatementGC = now
|
|
cutoff := now.Add(-it.window)
|
|
for host, s := range it.statements {
|
|
if s.time < cutoff {
|
|
delete(it.statements, host)
|
|
}
|
|
}
|
|
}
|
|
|
|
func (it *IPTracker) gcContact(now mclock.AbsTime) {
|
|
it.lastContactGC = now
|
|
cutoff := now.Add(-it.contactWindow)
|
|
for host, ct := range it.contact {
|
|
if ct < cutoff {
|
|
delete(it.contact, host)
|
|
}
|
|
}
|
|
}
|