plugeth/p2p/netutil/net.go
Felix Lange 9123eceb0f p2p, p2p/discover: misc connectivity improvements (#16069)
* p2p: add DialRatio for configuration of inbound vs. dialed connections

* p2p: add connection flags to PeerInfo

* p2p/netutil: add SameNet, DistinctNetSet

* p2p/discover: improve revalidation and seeding

This changes node revalidation to be periodic instead of on-demand. This
should prevent issues where dead nodes get stuck in closer buckets
because no other node will ever come along to replace them.

Every 5 seconds (on average), the last node in a random bucket is
checked and moved to the front of the bucket if it is still responding.
If revalidation fails, the last node is replaced by an entry of the
'replacement list' containing recently-seen nodes.

Most close buckets are removed because it's very unlikely we'll ever
encounter a node that would fall into any of those buckets.

Table seeding is also improved: we now require a few minutes of table
membership before considering a node as a potential seed node. This
should make it less likely to store short-lived nodes as potential
seeds.

* p2p/discover: fix nits in UDP transport

We would skip sending neighbors replies if there were fewer than
maxNeighbors results and CheckRelayIP returned an error for the last
one. While here, also resolve a TODO about pong reply tokens.
2018-02-12 14:36:09 +02:00

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// Copyright 2016 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 contains extensions to the net package.
package netutil
import (
"bytes"
"errors"
"fmt"
"net"
"sort"
"strings"
)
var lan4, lan6, special4, special6 Netlist
func init() {
// Lists from RFC 5735, RFC 5156,
// https://www.iana.org/assignments/iana-ipv4-special-registry/
lan4.Add("0.0.0.0/8") // "This" network
lan4.Add("10.0.0.0/8") // Private Use
lan4.Add("172.16.0.0/12") // Private Use
lan4.Add("192.168.0.0/16") // Private Use
lan6.Add("fe80::/10") // Link-Local
lan6.Add("fc00::/7") // Unique-Local
special4.Add("192.0.0.0/29") // IPv4 Service Continuity
special4.Add("192.0.0.9/32") // PCP Anycast
special4.Add("192.0.0.170/32") // NAT64/DNS64 Discovery
special4.Add("192.0.0.171/32") // NAT64/DNS64 Discovery
special4.Add("192.0.2.0/24") // TEST-NET-1
special4.Add("192.31.196.0/24") // AS112
special4.Add("192.52.193.0/24") // AMT
special4.Add("192.88.99.0/24") // 6to4 Relay Anycast
special4.Add("192.175.48.0/24") // AS112
special4.Add("198.18.0.0/15") // Device Benchmark Testing
special4.Add("198.51.100.0/24") // TEST-NET-2
special4.Add("203.0.113.0/24") // TEST-NET-3
special4.Add("255.255.255.255/32") // Limited Broadcast
// http://www.iana.org/assignments/iana-ipv6-special-registry/
special6.Add("100::/64")
special6.Add("2001::/32")
special6.Add("2001:1::1/128")
special6.Add("2001:2::/48")
special6.Add("2001:3::/32")
special6.Add("2001:4:112::/48")
special6.Add("2001:5::/32")
special6.Add("2001:10::/28")
special6.Add("2001:20::/28")
special6.Add("2001:db8::/32")
special6.Add("2002::/16")
}
// Netlist is a list of IP networks.
type Netlist []net.IPNet
// ParseNetlist parses a comma-separated list of CIDR masks.
// Whitespace and extra commas are ignored.
func ParseNetlist(s string) (*Netlist, error) {
ws := strings.NewReplacer(" ", "", "\n", "", "\t", "")
masks := strings.Split(ws.Replace(s), ",")
l := make(Netlist, 0)
for _, mask := range masks {
if mask == "" {
continue
}
_, n, err := net.ParseCIDR(mask)
if err != nil {
return nil, err
}
l = append(l, *n)
}
return &l, nil
}
// MarshalTOML implements toml.MarshalerRec.
func (l Netlist) MarshalTOML() interface{} {
list := make([]string, 0, len(l))
for _, net := range l {
list = append(list, net.String())
}
return list
}
// UnmarshalTOML implements toml.UnmarshalerRec.
func (l *Netlist) UnmarshalTOML(fn func(interface{}) error) error {
var masks []string
if err := fn(&masks); err != nil {
return err
}
for _, mask := range masks {
_, n, err := net.ParseCIDR(mask)
if err != nil {
return err
}
*l = append(*l, *n)
}
return nil
}
// Add parses a CIDR mask and appends it to the list. It panics for invalid masks and is
// intended to be used for setting up static lists.
func (l *Netlist) Add(cidr string) {
_, n, err := net.ParseCIDR(cidr)
if err != nil {
panic(err)
}
*l = append(*l, *n)
}
// Contains reports whether the given IP is contained in the list.
func (l *Netlist) Contains(ip net.IP) bool {
if l == nil {
return false
}
for _, net := range *l {
if net.Contains(ip) {
return true
}
}
return false
}
// IsLAN reports whether an IP is a local network address.
func IsLAN(ip net.IP) bool {
if ip.IsLoopback() {
return true
}
if v4 := ip.To4(); v4 != nil {
return lan4.Contains(v4)
}
return lan6.Contains(ip)
}
// IsSpecialNetwork reports whether an IP is located in a special-use network range
// This includes broadcast, multicast and documentation addresses.
func IsSpecialNetwork(ip net.IP) bool {
if ip.IsMulticast() {
return true
}
if v4 := ip.To4(); v4 != nil {
return special4.Contains(v4)
}
return special6.Contains(ip)
}
var (
errInvalid = errors.New("invalid IP")
errUnspecified = errors.New("zero address")
errSpecial = errors.New("special network")
errLoopback = errors.New("loopback address from non-loopback host")
errLAN = errors.New("LAN address from WAN host")
)
// CheckRelayIP reports whether an IP relayed from the given sender IP
// is a valid connection target.
//
// There are four rules:
// - Special network addresses are never valid.
// - Loopback addresses are OK if relayed by a loopback host.
// - LAN addresses are OK if relayed by a LAN host.
// - All other addresses are always acceptable.
func CheckRelayIP(sender, addr net.IP) error {
if len(addr) != net.IPv4len && len(addr) != net.IPv6len {
return errInvalid
}
if addr.IsUnspecified() {
return errUnspecified
}
if IsSpecialNetwork(addr) {
return errSpecial
}
if addr.IsLoopback() && !sender.IsLoopback() {
return errLoopback
}
if IsLAN(addr) && !IsLAN(sender) {
return errLAN
}
return nil
}
// SameNet reports whether two IP addresses have an equal prefix of the given bit length.
func SameNet(bits uint, ip, other net.IP) bool {
ip4, other4 := ip.To4(), other.To4()
switch {
case (ip4 == nil) != (other4 == nil):
return false
case ip4 != nil:
return sameNet(bits, ip4, other4)
default:
return sameNet(bits, ip.To16(), other.To16())
}
}
func sameNet(bits uint, ip, other net.IP) bool {
nb := int(bits / 8)
mask := ^byte(0xFF >> (bits % 8))
if mask != 0 && nb < len(ip) && ip[nb]&mask != other[nb]&mask {
return false
}
return nb <= len(ip) && bytes.Equal(ip[:nb], other[:nb])
}
// DistinctNetSet tracks IPs, ensuring that at most N of them
// fall into the same network range.
type DistinctNetSet struct {
Subnet uint // number of common prefix bits
Limit uint // maximum number of IPs in each subnet
members map[string]uint
buf net.IP
}
// Add adds an IP address to the set. It returns false (and doesn't add the IP) if the
// number of existing IPs in the defined range exceeds the limit.
func (s *DistinctNetSet) Add(ip net.IP) bool {
key := s.key(ip)
n := s.members[string(key)]
if n < s.Limit {
s.members[string(key)] = n + 1
return true
}
return false
}
// Remove removes an IP from the set.
func (s *DistinctNetSet) Remove(ip net.IP) {
key := s.key(ip)
if n, ok := s.members[string(key)]; ok {
if n == 1 {
delete(s.members, string(key))
} else {
s.members[string(key)] = n - 1
}
}
}
// Contains whether the given IP is contained in the set.
func (s DistinctNetSet) Contains(ip net.IP) bool {
key := s.key(ip)
_, ok := s.members[string(key)]
return ok
}
// Len returns the number of tracked IPs.
func (s DistinctNetSet) Len() int {
n := uint(0)
for _, i := range s.members {
n += i
}
return int(n)
}
// key encodes the map key for an address into a temporary buffer.
//
// The first byte of key is '4' or '6' to distinguish IPv4/IPv6 address types.
// The remainder of the key is the IP, truncated to the number of bits.
func (s *DistinctNetSet) key(ip net.IP) net.IP {
// Lazily initialize storage.
if s.members == nil {
s.members = make(map[string]uint)
s.buf = make(net.IP, 17)
}
// Canonicalize ip and bits.
typ := byte('6')
if ip4 := ip.To4(); ip4 != nil {
typ, ip = '4', ip4
}
bits := s.Subnet
if bits > uint(len(ip)*8) {
bits = uint(len(ip) * 8)
}
// Encode the prefix into s.buf.
nb := int(bits / 8)
mask := ^byte(0xFF >> (bits % 8))
s.buf[0] = typ
buf := append(s.buf[:1], ip[:nb]...)
if nb < len(ip) && mask != 0 {
buf = append(buf, ip[nb]&mask)
}
return buf
}
// String implements fmt.Stringer
func (s DistinctNetSet) String() string {
var buf bytes.Buffer
buf.WriteString("{")
keys := make([]string, 0, len(s.members))
for k := range s.members {
keys = append(keys, k)
}
sort.Strings(keys)
for i, k := range keys {
var ip net.IP
if k[0] == '4' {
ip = make(net.IP, 4)
} else {
ip = make(net.IP, 16)
}
copy(ip, k[1:])
fmt.Fprintf(&buf, "%v×%d", ip, s.members[k])
if i != len(keys)-1 {
buf.WriteString(" ")
}
}
buf.WriteString("}")
return buf.String()
}