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main.go
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158 lines (136 loc) · 4.03 KB
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package main
import (
"crypto/rand"
"encoding/base64"
"flag"
"fmt"
"io/ioutil"
"log"
"math/big"
"net"
"os"
"os/exec"
"os/signal"
"path/filepath"
"runtime"
"syscall"
"golang.org/x/crypto/curve25519"
"golang.zx2c4.com/wireguard/device"
"golang.zx2c4.com/wireguard/tun"
"golang.zx2c4.com/wireguard/conn"
)
func ensureKeys(dir string) (privBase64, pubBase64 string, created bool, err error) {
privPath := filepath.Join(dir, "server_private.key")
pubPath := filepath.Join(dir, "server_public.key")
// Check if keys exist
privBytes, errPriv := ioutil.ReadFile(privPath)
pubBytes, errPub := ioutil.ReadFile(pubPath)
if errPriv == nil && errPub == nil {
return string(privBytes), string(pubBytes), false, nil
}
// Generate new key pair
priv := make([]byte, 32)
_, err = rand.Read(priv)
if err != nil {
return "", "", false, err
}
priv[0] &= 248
priv[31] = (priv[31] & 127) | 64
pub, err := curve25519.X25519(priv, curve25519.Basepoint)
if err != nil {
return "", "", false, err
}
privBase64 = base64.StdEncoding.EncodeToString(priv)
pubBase64 = base64.StdEncoding.EncodeToString(pub)
// Ensure directory exists
if err := os.MkdirAll(dir, 0700); err != nil {
return "", "", false, err
}
if err := ioutil.WriteFile(privPath, []byte(privBase64), 0600); err != nil {
return "", "", false, err
}
if err := ioutil.WriteFile(pubPath, []byte(pubBase64), 0644); err != nil {
return "", "", false, err
}
return privBase64, pubBase64, true, nil
}
func firstUsableIP(subnet *net.IPNet) net.IP {
ip := subnet.IP.To4()
ipInt := big.NewInt(0).SetBytes(ip)
ipInt.Add(ipInt, big.NewInt(1)) // .1 is first usable
return net.IP(ipInt.Bytes())
}
func maskToDotted(mask net.IPMask) string {
return net.IP(mask).String()
}
func maskLength(mask net.IPMask) int {
ones, _ := mask.Size()
return ones
}
func main() {
subnetFlag := flag.String("subnet", "10.0.0.0/24", "Tunnel subnet (CIDR)")
flag.Parse()
// Ensure $HOME/.simplevpn dir and keys
homeDir, err := os.UserHomeDir()
if err != nil {
log.Fatalf("failed to get user home directory: %v", err)
}
keyDir := filepath.Join(homeDir, ".simplevpn")
_, pubKey, created, err := ensureKeys(keyDir)
if err != nil {
log.Fatalf("failed to ensure server keys: %v", err)
}
if created {
fmt.Printf("[SimpleVPN] Server public key: %s\n", pubKey)
}
_, subnet, err := net.ParseCIDR(*subnetFlag)
if err != nil {
log.Fatalf("invalid subnet: %v", err)
}
ipAddr := firstUsableIP(subnet).String()
cidr := fmt.Sprintf("%s/%d", ipAddr, maskLength(subnet.Mask))
tunName := "utun" // Use 'utun' for macOS compatibility
tunDev, err := tun.CreateTUN(tunName, 1420)
if err != nil {
log.Fatalf("failed to create TUN device: %v", err)
}
ifName, err := tunDev.Name()
if err != nil {
log.Printf("Warning: could not get interface name: %v", err)
} else {
log.Printf("Created TUN device: %s", ifName)
}
// Assign internal IP address based on OS
var cmd *exec.Cmd
switch runtime.GOOS {
case "darwin":
cmd = exec.Command("ifconfig", ifName, "inet", ipAddr, ipAddr, "netmask", maskToDotted(subnet.Mask), "up")
case "linux":
cmd = exec.Command("ip", "addr", "add", cidr, "dev", ifName)
upCmd := exec.Command("ip", "link", "set", "up", "dev", ifName)
if err := upCmd.Run(); err != nil {
log.Printf("Warning: failed to bring up interface: %v", err)
}
default:
log.Printf("OS %s not supported for automatic IP assignment", runtime.GOOS)
}
if cmd != nil {
if err := cmd.Run(); err != nil {
log.Fatalf("failed to assign IP address: %v", err)
}
log.Printf("Assigned IP %s to interface %s", ipAddr, ifName)
}
logger := device.NewLogger(device.LogLevelVerbose, "WGD: ")
bind := conn.NewDefaultBind()
dev := device.NewDevice(tunDev, bind, logger)
err = dev.Up()
if err != nil {
log.Fatalf("failed to bring up device: %v", err)
}
log.Printf("WireGuard device %s is up and running (embedded mode). Configure it using wg or wgctrl-go.", ifName)
c := make(chan os.Signal, 1)
signal.Notify(c, os.Interrupt, syscall.SIGTERM)
<-c
log.Println("Shutting down WireGuard device...")
dev.Close()
}