343 lines
9.2 KiB
Go
343 lines
9.2 KiB
Go
// Copyright 2016 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 contains extensions to the net package.
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package netutil
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import (
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"bytes"
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"errors"
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"fmt"
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"net"
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"net/netip"
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"slices"
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"strings"
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"golang.org/x/exp/maps"
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)
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var special4, special6 Netlist
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func init() {
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// Lists from RFC 5735, RFC 5156,
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// https://www.iana.org/assignments/iana-ipv4-special-registry/
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special4.Add("0.0.0.0/8") // "This" network.
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special4.Add("192.0.0.0/29") // IPv4 Service Continuity
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special4.Add("192.0.0.9/32") // PCP Anycast
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special4.Add("192.0.0.170/32") // NAT64/DNS64 Discovery
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special4.Add("192.0.0.171/32") // NAT64/DNS64 Discovery
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special4.Add("192.0.2.0/24") // TEST-NET-1
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special4.Add("192.31.196.0/24") // AS112
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special4.Add("192.52.193.0/24") // AMT
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special4.Add("192.88.99.0/24") // 6to4 Relay Anycast
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special4.Add("192.175.48.0/24") // AS112
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special4.Add("198.18.0.0/15") // Device Benchmark Testing
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special4.Add("198.51.100.0/24") // TEST-NET-2
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special4.Add("203.0.113.0/24") // TEST-NET-3
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special4.Add("255.255.255.255/32") // Limited Broadcast
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// http://www.iana.org/assignments/iana-ipv6-special-registry/
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special6.Add("100::/64")
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special6.Add("2001::/32")
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special6.Add("2001:1::1/128")
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special6.Add("2001:2::/48")
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special6.Add("2001:3::/32")
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special6.Add("2001:4:112::/48")
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special6.Add("2001:5::/32")
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special6.Add("2001:10::/28")
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special6.Add("2001:20::/28")
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special6.Add("2001:db8::/32")
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special6.Add("2002::/16")
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}
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// Netlist is a list of IP networks.
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type Netlist []netip.Prefix
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// ParseNetlist parses a comma-separated list of CIDR masks.
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// Whitespace and extra commas are ignored.
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func ParseNetlist(s string) (*Netlist, error) {
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ws := strings.NewReplacer(" ", "", "\n", "", "\t", "")
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masks := strings.Split(ws.Replace(s), ",")
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l := make(Netlist, 0)
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for _, mask := range masks {
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if mask == "" {
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continue
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}
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prefix, err := netip.ParsePrefix(mask)
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if err != nil {
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return nil, err
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}
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l = append(l, prefix)
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}
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return &l, nil
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}
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// MarshalTOML implements toml.MarshalerRec.
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func (l Netlist) MarshalTOML() interface{} {
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list := make([]string, 0, len(l))
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for _, net := range l {
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list = append(list, net.String())
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}
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return list
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}
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// UnmarshalTOML implements toml.UnmarshalerRec.
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func (l *Netlist) UnmarshalTOML(fn func(interface{}) error) error {
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var masks []string
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if err := fn(&masks); err != nil {
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return err
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}
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for _, mask := range masks {
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prefix, err := netip.ParsePrefix(mask)
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if err != nil {
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return err
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}
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*l = append(*l, prefix)
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}
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return nil
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}
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// Add parses a CIDR mask and appends it to the list. It panics for invalid masks and is
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// intended to be used for setting up static lists.
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func (l *Netlist) Add(cidr string) {
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prefix, err := netip.ParsePrefix(cidr)
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if err != nil {
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panic(err)
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}
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*l = append(*l, prefix)
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}
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// Contains reports whether the given IP is contained in the list.
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func (l *Netlist) Contains(ip net.IP) bool {
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return l.ContainsAddr(IPToAddr(ip))
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}
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// ContainsAddr reports whether the given IP is contained in the list.
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func (l *Netlist) ContainsAddr(ip netip.Addr) bool {
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if l == nil {
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return false
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}
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for _, net := range *l {
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if net.Contains(ip) {
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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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// IsLAN reports whether an IP is a local network address.
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func IsLAN(ip net.IP) bool {
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return AddrIsLAN(IPToAddr(ip))
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}
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// AddrIsLAN reports whether an IP is a local network address.
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func AddrIsLAN(ip netip.Addr) bool {
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if ip.Is4In6() {
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ip = netip.AddrFrom4(ip.As4())
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}
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if ip.IsLoopback() {
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return true
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}
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return ip.IsPrivate() || ip.IsLinkLocalUnicast()
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}
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// IsSpecialNetwork reports whether an IP is located in a special-use network range
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// This includes broadcast, multicast and documentation addresses.
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func IsSpecialNetwork(ip net.IP) bool {
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return AddrIsSpecialNetwork(IPToAddr(ip))
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}
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// AddrIsSpecialNetwork reports whether an IP is located in a special-use network range
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// This includes broadcast, multicast and documentation addresses.
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func AddrIsSpecialNetwork(ip netip.Addr) bool {
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if ip.Is4In6() {
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ip = netip.AddrFrom4(ip.As4())
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}
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if ip.IsMulticast() {
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return true
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}
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if ip.Is4() {
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return special4.ContainsAddr(ip)
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}
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return special6.ContainsAddr(ip)
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}
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var (
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errInvalid = errors.New("invalid IP")
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errUnspecified = errors.New("zero address")
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errSpecial = errors.New("special network")
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errLoopback = errors.New("loopback address from non-loopback host")
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errLAN = errors.New("LAN address from WAN host")
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)
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// CheckRelayIP reports whether an IP relayed from the given sender IP
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// is a valid connection target.
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//
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// There are four rules:
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// - Special network addresses are never valid.
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// - Loopback addresses are OK if relayed by a loopback host.
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// - LAN addresses are OK if relayed by a LAN host.
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// - All other addresses are always acceptable.
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func CheckRelayIP(sender, addr net.IP) error {
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return CheckRelayAddr(IPToAddr(sender), IPToAddr(addr))
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}
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// CheckRelayAddr reports whether an IP relayed from the given sender IP
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// is a valid connection target.
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//
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// There are four rules:
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// - Special network addresses are never valid.
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// - Loopback addresses are OK if relayed by a loopback host.
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// - LAN addresses are OK if relayed by a LAN host.
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// - All other addresses are always acceptable.
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func CheckRelayAddr(sender, addr netip.Addr) error {
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if !addr.IsValid() {
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return errInvalid
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}
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if addr.IsUnspecified() {
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return errUnspecified
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}
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if AddrIsSpecialNetwork(addr) {
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return errSpecial
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}
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if addr.IsLoopback() && !sender.IsLoopback() {
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return errLoopback
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}
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if AddrIsLAN(addr) && !AddrIsLAN(sender) {
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return errLAN
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}
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return nil
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}
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// SameNet reports whether two IP addresses have an equal prefix of the given bit length.
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func SameNet(bits uint, ip, other net.IP) bool {
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ip4, other4 := ip.To4(), other.To4()
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switch {
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case (ip4 == nil) != (other4 == nil):
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return false
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case ip4 != nil:
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return sameNet(bits, ip4, other4)
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default:
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return sameNet(bits, ip.To16(), other.To16())
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}
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}
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func sameNet(bits uint, ip, other net.IP) bool {
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nb := int(bits / 8)
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mask := ^byte(0xFF >> (bits % 8))
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if mask != 0 && nb < len(ip) && ip[nb]&mask != other[nb]&mask {
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return false
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}
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return nb <= len(ip) && ip[:nb].Equal(other[:nb])
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}
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// DistinctNetSet tracks IPs, ensuring that at most N of them
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// fall into the same network range.
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type DistinctNetSet struct {
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Subnet uint // number of common prefix bits
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Limit uint // maximum number of IPs in each subnet
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members map[netip.Prefix]uint
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}
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// Add adds an IP address to the set. It returns false (and doesn't add the IP) if the
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// number of existing IPs in the defined range exceeds the limit.
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func (s *DistinctNetSet) Add(ip net.IP) bool {
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return s.AddAddr(IPToAddr(ip))
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}
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// AddAddr adds an IP address to the set. It returns false (and doesn't add the IP) if the
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// number of existing IPs in the defined range exceeds the limit.
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func (s *DistinctNetSet) AddAddr(ip netip.Addr) bool {
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key := s.key(ip)
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n := s.members[key]
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if n < s.Limit {
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s.members[key] = n + 1
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return true
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}
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return false
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}
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// Remove removes an IP from the set.
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func (s *DistinctNetSet) Remove(ip net.IP) {
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s.RemoveAddr(IPToAddr(ip))
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}
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// RemoveAddr removes an IP from the set.
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func (s *DistinctNetSet) RemoveAddr(ip netip.Addr) {
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key := s.key(ip)
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if n, ok := s.members[key]; ok {
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if n == 1 {
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delete(s.members, key)
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} else {
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s.members[key] = n - 1
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}
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}
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}
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// Contains reports whether the given IP is contained in the set.
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func (s DistinctNetSet) Contains(ip net.IP) bool {
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return s.ContainsAddr(IPToAddr(ip))
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}
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// ContainsAddr reports whether the given IP is contained in the set.
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func (s DistinctNetSet) ContainsAddr(ip netip.Addr) bool {
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key := s.key(ip)
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_, ok := s.members[key]
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return ok
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}
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// Len returns the number of tracked IPs.
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func (s DistinctNetSet) Len() int {
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n := uint(0)
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for _, i := range s.members {
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n += i
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}
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return int(n)
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}
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// key returns the map key for ip.
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func (s *DistinctNetSet) key(ip netip.Addr) netip.Prefix {
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// Lazily initialize storage.
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if s.members == nil {
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s.members = make(map[netip.Prefix]uint)
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}
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p, err := ip.Prefix(int(s.Subnet))
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if err != nil {
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panic(err)
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}
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return p
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}
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// String implements fmt.Stringer
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func (s DistinctNetSet) String() string {
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keys := maps.Keys(s.members)
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slices.SortFunc(keys, func(a, b netip.Prefix) int {
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return strings.Compare(a.String(), b.String())
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})
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var buf bytes.Buffer
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buf.WriteString("{")
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for i, k := range keys {
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fmt.Fprintf(&buf, "%v×%d", k, s.members[k])
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if i != len(keys)-1 {
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buf.WriteString(" ")
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}
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}
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buf.WriteString("}")
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return buf.String()
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}
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