155 lines
2.8 KiB
Go
155 lines
2.8 KiB
Go
package main
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import (
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"context"
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"errors"
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"fmt"
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"log"
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"mpbl3p/config"
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"mpbl3p/flags"
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"mpbl3p/tun"
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"os"
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"os/signal"
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"strconv"
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"syscall"
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)
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const (
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ENV_NC_TUN_FD = "NC_TUN_FD"
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ENV_NC_CONFIG_PATH = "NC_CONFIG_PATH"
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)
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func main() {
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log.SetFlags(log.Ldate | log.Ltime | log.Llongfile)
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if _, exists := os.LookupEnv(ENV_NC_TUN_FD); !exists {
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// we are the parent process
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// 1) process arguments
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// 2) validate config
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// 2) create a tun adapter
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// 3) spawn a child
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// 4) exit
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o, err := flags.ParseFlags()
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if err != nil {
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if errors.Is(err, flags.PrintedHelpErr) {
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return
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}
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panic(err)
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}
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log.Println("loading config...")
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c, err := config.LoadConfig(o.ConfigFile)
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if err != nil {
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panic(err)
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}
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log.Println("creating tun adapter...")
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t, err := tun.NewTun(o.Positional.InterfaceName, int(c.Host.MTU))
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if err != nil {
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panic(err)
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}
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if o.Foreground {
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if err := os.Setenv(ENV_NC_TUN_FD, fmt.Sprintf("%d", t.File().Fd())); err != nil {
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panic(err)
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}
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if err := os.Setenv(ENV_NC_CONFIG_PATH, o.ConfigFile); err != nil {
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panic(err)
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}
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log.Println("switching to foreground")
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goto FOREGROUND
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}
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files := make([]*os.File, 4)
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files[0], _ = os.Open(os.DevNull) // stdin
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files[1], _ = os.Open(os.DevNull) // stderr
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files[2], _ = os.Open(os.DevNull) // stdout
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files[3] = t.File()
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env := os.Environ()
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env = append(env, fmt.Sprintf("%s=3", ENV_NC_TUN_FD))
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env = append(env, fmt.Sprintf("%s=%s", ENV_NC_CONFIG_PATH, o.ConfigFile))
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attr := os.ProcAttr{
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Env: env,
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Files: files,
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}
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path, err := os.Executable()
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if err != nil {
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panic(err)
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}
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process, err := os.StartProcess(
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path,
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os.Args,
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&attr,
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)
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if err != nil {
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panic(err)
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}
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pidFile, err := os.Create(o.PidFile)
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if err != nil {
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panic(err)
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}
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if _, err := fmt.Fprintf(pidFile, "%d", process.Pid); err != nil {
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panic(err)
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}
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_ = process.Release()
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return
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}
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// we are the child process
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// 1) recreate tun adapter from file descriptor
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// 2) launch proxy
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FOREGROUND:
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log.Println("loading config...")
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c, err := config.LoadConfig(os.Getenv(ENV_NC_CONFIG_PATH))
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if err != nil {
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panic(err)
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}
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log.Println("connecting tun adapter...")
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tunFd, err := strconv.ParseUint(os.Getenv(ENV_NC_TUN_FD), 10, 64)
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if err != nil {
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panic(err)
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}
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t, err := tun.NewFromFile(uintptr(tunFd), int(c.Host.MTU))
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if err != nil {
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panic(err)
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}
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defer func() {
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if err := t.Close(); err != nil {
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panic(err)
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}
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}()
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log.Println("building config...")
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ctx, cancel := context.WithCancel(context.Background())
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defer cancel()
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p, err := c.Build(ctx, t, t)
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if err != nil {
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panic(err)
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}
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log.Println("starting proxy...")
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p.Start()
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log.Println("proxy started")
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signals := make(chan os.Signal)
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signal.Notify(signals, syscall.SIGTERM, syscall.SIGINT)
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<-signals
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log.Println("exiting...")
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}
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