kilo/pkg/wireguard/conf.go
Lucas Servén Marín 35390054ba
pkg: deduplicate peer IP addresses
We need to defensively deduplicate peer allowed IPs.
If two peers claim the same IP, the WireGuard configuration
could flap, causing the interface to churn.
2019-05-10 02:07:42 +02:00

389 lines
9.2 KiB
Go

// Copyright 2019 the Kilo authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package wireguard
import (
"bufio"
"bytes"
"fmt"
"net"
"sort"
"strconv"
"strings"
)
type section string
type key string
const (
separator = "="
interfaceSection section = "Interface"
peerSection section = "Peer"
listenPortKey key = "ListenPort"
allowedIPsKey key = "AllowedIPs"
endpointKey key = "Endpoint"
persistentKeepaliveKey key = "PersistentKeepalive"
privateKeyKey key = "PrivateKey"
publicKeyKey key = "PublicKey"
)
// Conf represents a WireGuard configuration file.
type Conf struct {
Interface *Interface
Peers []*Peer
}
// Interface represents the `interface` section of a WireGuard configuration.
type Interface struct {
ListenPort uint32
PrivateKey []byte
}
// Peer represents a `peer` section of a WireGuard configuration.
type Peer struct {
AllowedIPs []*net.IPNet
Endpoint *Endpoint
PersistentKeepalive int
PublicKey []byte
}
// DeduplicateIPs eliminates duplicate allowed IPs.
func (p *Peer) DeduplicateIPs() {
var ips []*net.IPNet
seen := make(map[string]struct{})
for _, ip := range p.AllowedIPs {
if _, ok := seen[ip.String()]; ok {
continue
}
ips = append(ips, ip)
seen[ip.String()] = struct{}{}
}
p.AllowedIPs = ips
}
// Endpoint represents an `endpoint` key of a `peer` section.
type Endpoint struct {
IP net.IP
Port uint32
}
// Parse parses a given WireGuard configuration file and produces a Conf struct.
func Parse(buf []byte) *Conf {
var (
active section
ai *net.IPNet
kv []string
c Conf
err error
iface *Interface
i int
ip, ip4 net.IP
k key
line, v string
peer *Peer
port uint64
)
s := bufio.NewScanner(bytes.NewBuffer(buf))
for s.Scan() {
line = strings.TrimSpace(s.Text())
// Skip comments.
if strings.HasPrefix(line, "#") {
continue
}
// Line is a section title.
if strings.HasPrefix(line, "[") {
if peer != nil {
c.Peers = append(c.Peers, peer)
peer = nil
}
if iface != nil {
c.Interface = iface
iface = nil
}
active = section(strings.TrimSpace(strings.Trim(line, "[]")))
switch active {
case interfaceSection:
iface = new(Interface)
case peerSection:
peer = new(Peer)
}
continue
}
kv = strings.SplitN(line, separator, 2)
if len(kv) != 2 {
continue
}
k = key(strings.TrimSpace(kv[0]))
v = strings.TrimSpace(kv[1])
switch active {
case interfaceSection:
switch k {
case listenPortKey:
port, err = strconv.ParseUint(v, 10, 32)
if err != nil {
continue
}
iface.ListenPort = uint32(port)
case privateKeyKey:
iface.PrivateKey = []byte(v)
}
case peerSection:
switch k {
case allowedIPsKey:
// Reuse string slice.
kv = strings.Split(v, ",")
for i = range kv {
ip, ai, err = net.ParseCIDR(strings.TrimSpace(kv[i]))
if err != nil {
continue
}
if ip4 = ip.To4(); ip4 != nil {
ip = ip4
} else {
ip = ip.To16()
}
ai.IP = ip
peer.AllowedIPs = append(peer.AllowedIPs, ai)
}
case endpointKey:
// Reuse string slice.
kv = strings.Split(v, ":")
if len(kv) != 2 {
continue
}
ip = net.ParseIP(kv[0])
if ip == nil {
continue
}
port, err = strconv.ParseUint(kv[1], 10, 32)
if err != nil {
continue
}
if ip4 = ip.To4(); ip4 != nil {
ip = ip4
} else {
ip = ip.To16()
}
peer.Endpoint = &Endpoint{
IP: ip,
Port: uint32(port),
}
case persistentKeepaliveKey:
i, err = strconv.Atoi(v)
if err != nil {
continue
}
peer.PersistentKeepalive = i
case publicKeyKey:
peer.PublicKey = []byte(v)
}
}
}
if peer != nil {
c.Peers = append(c.Peers, peer)
}
if iface != nil {
c.Interface = iface
}
return &c
}
// Bytes renders a WireGuard configuration to bytes.
func (c *Conf) Bytes() ([]byte, error) {
var err error
buf := bytes.NewBuffer(make([]byte, 0, 512))
if c.Interface != nil {
if err = writeSection(buf, interfaceSection); err != nil {
return nil, fmt.Errorf("failed to write interface: %v", err)
}
if err = writePKey(buf, privateKeyKey, c.Interface.PrivateKey); err != nil {
return nil, fmt.Errorf("failed to write private key: %v", err)
}
if err = writeValue(buf, listenPortKey, strconv.FormatUint(uint64(c.Interface.ListenPort), 10)); err != nil {
return nil, fmt.Errorf("failed to write listen port: %v", err)
}
}
for i, p := range c.Peers {
// Add newlines to make the formatting nicer.
if i == 0 && c.Interface != nil || i != 0 {
if err = buf.WriteByte('\n'); err != nil {
return nil, err
}
}
if err = writeSection(buf, peerSection); err != nil {
return nil, fmt.Errorf("failed to write interface: %v", err)
}
if err = writeAllowedIPs(buf, p.AllowedIPs); err != nil {
return nil, fmt.Errorf("failed to write allowed IPs: %v", err)
}
if err = writeEndpoint(buf, p.Endpoint); err != nil {
return nil, fmt.Errorf("failed to write endpoint: %v", err)
}
if err = writeValue(buf, persistentKeepaliveKey, strconv.Itoa(p.PersistentKeepalive)); err != nil {
return nil, fmt.Errorf("failed to write persistent keepalive: %v", err)
}
if err = writePKey(buf, publicKeyKey, p.PublicKey); err != nil {
return nil, fmt.Errorf("failed to write public key: %v", err)
}
}
return buf.Bytes(), nil
}
// Equal checks if two WireGuare configurations are equivalent.
func (c *Conf) Equal(b *Conf) bool {
if (c.Interface == nil) != (b.Interface == nil) {
return false
}
if c.Interface != nil {
if c.Interface.ListenPort != b.Interface.ListenPort || !bytes.Equal(c.Interface.PrivateKey, b.Interface.PrivateKey) {
return false
}
}
if len(c.Peers) != len(b.Peers) {
return false
}
sortPeers(c.Peers)
sortPeers(b.Peers)
for i := range c.Peers {
if len(c.Peers[i].AllowedIPs) != len(b.Peers[i].AllowedIPs) {
return false
}
sortCIDRs(c.Peers[i].AllowedIPs)
sortCIDRs(b.Peers[i].AllowedIPs)
for j := range c.Peers[i].AllowedIPs {
if c.Peers[i].AllowedIPs[j].String() != b.Peers[i].AllowedIPs[j].String() {
return false
}
}
if (c.Peers[i].Endpoint == nil) != (b.Peers[i].Endpoint == nil) {
return false
}
if c.Peers[i].Endpoint != nil {
if !c.Peers[i].Endpoint.IP.Equal(b.Peers[i].Endpoint.IP) || c.Peers[i].Endpoint.Port != b.Peers[i].Endpoint.Port {
return false
}
}
if c.Peers[i].PersistentKeepalive != b.Peers[i].PersistentKeepalive || !bytes.Equal(c.Peers[i].PublicKey, b.Peers[i].PublicKey) {
return false
}
}
return true
}
func sortPeers(peers []*Peer) {
sort.Slice(peers, func(i, j int) bool {
if bytes.Compare(peers[i].PublicKey, peers[j].PublicKey) < 0 {
return true
}
return false
})
}
func sortCIDRs(cidrs []*net.IPNet) {
sort.Slice(cidrs, func(i, j int) bool {
return cidrs[i].String() < cidrs[j].String()
})
}
func writeAllowedIPs(buf *bytes.Buffer, ais []*net.IPNet) error {
if len(ais) == 0 {
return nil
}
var err error
if err = writeKey(buf, allowedIPsKey); err != nil {
return err
}
for i := range ais {
if i != 0 {
if _, err = buf.WriteString(", "); err != nil {
return err
}
}
if _, err = buf.WriteString(ais[i].String()); err != nil {
return err
}
}
return buf.WriteByte('\n')
}
func writePKey(buf *bytes.Buffer, k key, b []byte) error {
if len(b) == 0 {
return nil
}
var err error
if err = writeKey(buf, k); err != nil {
return err
}
if _, err = buf.Write(b); err != nil {
return err
}
return buf.WriteByte('\n')
}
func writeValue(buf *bytes.Buffer, k key, v string) error {
var err error
if err = writeKey(buf, k); err != nil {
return err
}
if _, err = buf.WriteString(v); err != nil {
return err
}
return buf.WriteByte('\n')
}
func writeEndpoint(buf *bytes.Buffer, e *Endpoint) error {
if e == nil {
return nil
}
var err error
if err = writeKey(buf, endpointKey); err != nil {
return err
}
if _, err = buf.WriteString(e.IP.String()); err != nil {
return err
}
if err = buf.WriteByte(':'); err != nil {
return err
}
if _, err = buf.WriteString(strconv.FormatUint(uint64(e.Port), 10)); err != nil {
return err
}
return buf.WriteByte('\n')
}
func writeSection(buf *bytes.Buffer, s section) error {
var err error
if err = buf.WriteByte('['); err != nil {
return err
}
if _, err = buf.WriteString(string(s)); err != nil {
return err
}
if err = buf.WriteByte(']'); err != nil {
return err
}
return buf.WriteByte('\n')
}
func writeKey(buf *bytes.Buffer, k key) error {
var err error
if _, err = buf.WriteString(string(k)); err != nil {
return err
}
_, err = buf.WriteString(" = ")
return err
}