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package wireguard
import (
"bytes"
"encoding/binary"
"fmt"
"net"
"os/exec"
"strings"
"golang.org/x/sys/unix"
)
type Peer struct {
IPAddr net.IP
PublicKey string
PrivateKey string
}
type Service interface {
// GenerateKey() (string, error)
Up(iface string, network string, listenPort string) (string, error)
Down() error
NewPeer() (*Peer, error)
RemovePeer(peer *Peer) error
PublicKey() string
}
type service struct {
ipNet *net.IPNet
startIP uint32
endIP uint32
nextIP uint32
iface string
privateKey string
publicKey string
}
func NewService() Service {
return &service{}
}
func (s *service) Up(iface string, network string, listenPort string) (string, error) {
_, ipNet, err := net.ParseCIDR(network)
if err != nil {
return "", fmt.Errorf("cannot parse CIDR: %w", err)
}
s.ipNet = ipNet
mask := binary.BigEndian.Uint32(ipNet.Mask)
s.startIP = binary.BigEndian.Uint32(ipNet.IP)
s.endIP = (s.startIP & mask) | (mask ^ 0xffffffff)
s.nextIP = s.startIP
private, err := s.generateKey()
if err != nil {
return "", fmt.Errorf("cannot generate private key: %w", err)
}
public, err := s.getPublicKey(private)
if err != nil {
return "", fmt.Errorf("cannot get public key: %w", err)
}
fd, err := memfile("wg", []byte(private))
addInterface := fmt.Sprintf("ip link add dev %s type wireguard", iface)
addAddress := fmt.Sprintf("ip addr add %s dev %s", network, iface)
setPrivateKey := fmt.Sprintf("wg set %s private-key /dev/fd/%d listen-port %s", iface, fd, listenPort)
ifaceUp := fmt.Sprintf("ip link set %s up", iface)
cmd := exec.Command("bash", "-c", fmt.Sprintf("%s; %s; %s; %s", addInterface, addAddress, setPrivateKey, ifaceUp))
_, err = cmd.Output()
if err != nil {
return "", fmt.Errorf("cannot bring WireGuard interface up: %w", err)
}
s.iface = iface
s.privateKey = private
s.publicKey = public
return public, nil
}
func (s *service) Down() error {
cmd := exec.Command("bash", "-c", fmt.Sprintf("ip link delete dev %s", s.iface))
_, err := cmd.Output()
if err != nil {
return fmt.Errorf("cannot bring WireGuard interface down: %w", err)
}
return nil
}
func (s *service) NewPeer() (*Peer, error) {
private, err := s.generateKey()
if err != nil {
return nil, fmt.Errorf("cannot generate private key: %w", err)
}
public, err := s.getPublicKey(private)
if err != nil {
return nil, fmt.Errorf("cannot get public key: %w", err)
}
ipAddress, err := s.getNextIP()
if err != nil {
return nil, fmt.Errorf("could not assign new IP: %w", err)
}
cmd := exec.Command("bash", "-c", fmt.Sprintf("wg set %s peer %s allowed-ips %s/32", s.iface, public, ipAddress.String()))
output, err := cmd.CombinedOutput()
if err != nil {
return nil, fmt.Errorf("cannot add peer: %s: %w", string(output), err)
}
return &Peer{
IPAddr: ipAddress,
PrivateKey: private,
PublicKey: public,
}, nil
}
func (s *service) RemovePeer(peer *Peer) error {
cmd := exec.Command("bash", "-c", fmt.Sprintf("wg set %s peer %s remove", s.iface, peer.PublicKey))
_, err := cmd.Output()
if err != nil {
return fmt.Errorf("cannot remove peer: %w", err)
}
return nil
}
func (s *service) PublicKey() string {
return s.publicKey
}
func (s *service) getNextIP() (net.IP, error) {
for {
if s.nextIP == s.endIP {
return net.IP{}, fmt.Errorf("no more IP addresses remaining")
}
ip := make(net.IP, 4)
binary.BigEndian.PutUint32(ip, s.nextIP)
if ip[3] != 0 && ip[3] != 255 {
s.nextIP++
return ip, nil
}
s.nextIP++
}
}
func (s *service) generateKey() (string, error) {
cmd := exec.Command("wg", "genkey")
stdout, err := cmd.Output()
if err != nil {
return "", err
}
return strings.Replace(string(stdout[:]), "\n", "", -1), nil
}
func (s *service) getPublicKey(private string) (string, error) {
cmd := exec.Command("wg", "pubkey")
cmd.Stdin = bytes.NewBufferString(private)
stdout, err := cmd.Output()
if err != nil {
return "", err
}
return strings.Replace(string(stdout[:]), "\n", "", -1), nil
}
func memfile(name string, b []byte) (int, error) {
fd, err := unix.MemfdCreate(name, 0)
if err != nil {
return 0, fmt.Errorf("MemfdCreate: %v", err)
}
err = unix.Ftruncate(fd, int64(len(b)))
if err != nil {
return 0, fmt.Errorf("Ftruncate: %v", err)
}
data, err := unix.Mmap(fd, 0, len(b), unix.PROT_READ|unix.PROT_WRITE, unix.MAP_SHARED)
if err != nil {
return 0, fmt.Errorf("Mmap: %v", err)
}
copy(data, b)
err = unix.Munmap(data)
if err != nil {
return 0, fmt.Errorf("Munmap: %v", err)
}
return fd, nil
}
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