From c831778ef250d1eb2aeaa2d87298c821f65e6cc3 Mon Sep 17 00:00:00 2001 From: Felix Lange Date: Fri, 21 Sep 2018 11:12:36 +0200 Subject: [PATCH] p2p/netutil: add IPTracker --- p2p/netutil/iptrack.go | 116 ++++++++++++++++++++++++++++++++++++ p2p/netutil/iptrack_test.go | 85 ++++++++++++++++++++++++++ 2 files changed, 201 insertions(+) create mode 100644 p2p/netutil/iptrack.go create mode 100644 p2p/netutil/iptrack_test.go diff --git a/p2p/netutil/iptrack.go b/p2p/netutil/iptrack.go new file mode 100644 index 0000000000..7346b888a3 --- /dev/null +++ b/p2p/netutil/iptrack.go @@ -0,0 +1,116 @@ +// 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 . + +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 + // TODO add DistinctNetSet for additional protection +} + +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. +func (it *IPTracker) PredictFullConeNAT() bool { + now := it.clock.Now() + it.gcContact(now) + it.gcStatements(now) + for host := range it.statements { + if _, ok := it.contact[host]; !ok { + 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) + 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) { + it.statements[host] = ipStatement{endpoint, it.clock.Now()} +} + +// AddContact records that a packet containing endpoint information has been sent to a certain host. +func (it *IPTracker) AddContact(host string) { + it.contact[host] = it.clock.Now() +} + +func (it *IPTracker) gcStatements(now mclock.AbsTime) { + 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) { + cutoff := now.Add(-it.contactWindow) + for host, ct := range it.contact { + if ct < cutoff { + delete(it.contact, host) + } + } +} diff --git a/p2p/netutil/iptrack_test.go b/p2p/netutil/iptrack_test.go new file mode 100644 index 0000000000..20e6560884 --- /dev/null +++ b/p2p/netutil/iptrack_test.go @@ -0,0 +1,85 @@ +// 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 . + +package netutil + +import ( + "testing" + "time" + + "github.com/ethereum/go-ethereum/common/mclock" +) + +const ( + opStatement = iota + opContact + opPredict +) + +type iptrackTestEvent struct { + op int + time int // absolute, in milliseconds + ip, from string +} + +func TestIPTracker(t *testing.T) { + tests := map[string][]iptrackTestEvent{ + "minStatements": { + {opPredict, 0, "", ""}, + {opStatement, 0, "127.0.0.1", "127.0.0.2"}, + {opPredict, 1000, "", ""}, + {opStatement, 1000, "127.0.0.1", "127.0.0.3"}, + {opPredict, 1000, "", ""}, + {opStatement, 1000, "127.0.0.1", "127.0.0.4"}, + {opPredict, 1000, "127.0.0.1", ""}, + }, + "window": { + {opStatement, 0, "127.0.0.1", "127.0.0.2"}, + {opStatement, 2000, "127.0.0.1", "127.0.0.3"}, + {opStatement, 3000, "127.0.0.1", "127.0.0.4"}, + {opPredict, 10000, "127.0.0.1", ""}, + {opPredict, 10001, "", ""}, // first statement expired + {opStatement, 10100, "127.0.0.1", "127.0.0.2"}, + {opPredict, 10200, "127.0.0.1", ""}, + }, + } + + for name, test := range tests { + t.Run(name, func(t *testing.T) { runIPTrackerTest(t, test) }) + } +} + +func runIPTrackerTest(t *testing.T, evs []iptrackTestEvent) { + var ( + clock mclock.Simulated + it = NewIPTracker(10*time.Second, 10*time.Second, 3) + ) + it.clock = &clock + for i, ev := range evs { + evtime := time.Duration(ev.time) * time.Millisecond + clock.Run(evtime - time.Duration(clock.Now())) + switch ev.op { + case opStatement: + it.AddStatement(ev.from, ev.ip) + case opContact: + it.AddContact(ev.from) + case opPredict: + if pred := it.PredictEndpoint(); pred != ev.ip { + t.Errorf("op %d: wrong prediction %q, want %q", i, pred, ev.ip) + } + } + } +}