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tailscale/cmd/tailscaled/tailscaled.go

766 lines
23 KiB
Go

// Copyright (c) Tailscale Inc & AUTHORS
// SPDX-License-Identifier: BSD-3-Clause
//go:build go1.19
// The tailscaled program is the Tailscale client daemon. It's configured
// and controlled via the tailscale CLI program.
//
// It primarily supports Linux, though other systems will likely be
// supported in the future.
package main // import "tailscale.com/cmd/tailscaled"
import (
"context"
"errors"
"flag"
"fmt"
"log"
"net"
"net/http"
"net/http/pprof"
"net/netip"
"os"
"os/signal"
"path/filepath"
"runtime"
"strconv"
"strings"
"syscall"
"time"
"tailscale.com/cmd/tailscaled/childproc"
"tailscale.com/control/controlclient"
"tailscale.com/envknob"
"tailscale.com/ipn/ipnlocal"
"tailscale.com/ipn/ipnserver"
"tailscale.com/ipn/store"
"tailscale.com/logpolicy"
"tailscale.com/logtail"
"tailscale.com/net/dns"
"tailscale.com/net/dnsfallback"
"tailscale.com/net/netmon"
"tailscale.com/net/netns"
"tailscale.com/net/proxymux"
"tailscale.com/net/socks5"
"tailscale.com/net/tsdial"
"tailscale.com/net/tshttpproxy"
"tailscale.com/net/tstun"
"tailscale.com/paths"
"tailscale.com/safesocket"
"tailscale.com/smallzstd"
"tailscale.com/syncs"
"tailscale.com/tsd"
"tailscale.com/tsweb/varz"
"tailscale.com/types/flagtype"
"tailscale.com/types/logger"
"tailscale.com/types/logid"
"tailscale.com/util/clientmetric"
"tailscale.com/util/multierr"
"tailscale.com/util/osshare"
"tailscale.com/version"
"tailscale.com/version/distro"
"tailscale.com/wgengine"
"tailscale.com/wgengine/netstack"
"tailscale.com/wgengine/router"
)
// defaultTunName returns the default tun device name for the platform.
func defaultTunName() string {
switch runtime.GOOS {
case "openbsd":
return "tun"
case "windows":
return "Tailscale"
case "darwin":
// "utun" is recognized by wireguard-go/tun/tun_darwin.go
// as a magic value that uses/creates any free number.
return "utun"
case "linux":
switch distro.Get() {
case distro.Synology:
// Try TUN, but fall back to userspace networking if needed.
// See https://github.com/tailscale/tailscale-synology/issues/35
return "tailscale0,userspace-networking"
case distro.Gokrazy:
// Gokrazy doesn't yet work in tun mode because the whole
// Gokrazy thing is no C code, and Tailscale currently
// depends on the iptables binary for Linux's
// wgengine/router.
// But on Gokrazy there's no legacy iptables, so we could use netlink
// to program nft-iptables directly. It just isn't done yet;
// see https://github.com/tailscale/tailscale/issues/391
//
// But Gokrazy does have the tun module built-in, so users
// can still run --tun=tailscale0 if they wish, if they
// arrange for iptables to be present or run in "tailscale
// up --netfilter-mode=off" mode, perhaps. Untested.
return "userspace-networking"
}
}
return "tailscale0"
}
// defaultPort returns the default UDP port to listen on for disco+wireguard.
// By default it returns 0, to pick one randomly from the kernel.
// If the environment variable PORT is set, that's used instead.
// The PORT environment variable is chosen to match what the Linux systemd
// unit uses, to make documentation more consistent.
func defaultPort() uint16 {
if s := envknob.String("PORT"); s != "" {
if p, err := strconv.ParseUint(s, 10, 16); err == nil {
return uint16(p)
}
}
if envknob.GOOS() == "windows" {
return 41641
}
return 0
}
var args struct {
// tunname is a /dev/net/tun tunnel name ("tailscale0"), the
// string "userspace-networking", "tap:TAPNAME[:BRIDGENAME]"
// or comma-separated list thereof.
tunname string
cleanup bool
debug string
port uint16
statepath string
statedir string
socketpath string
birdSocketPath string
verbose int
socksAddr string // listen address for SOCKS5 server
httpProxyAddr string // listen address for HTTP proxy server
disableLogs bool
}
var (
installSystemDaemon func([]string) error // non-nil on some platforms
uninstallSystemDaemon func([]string) error // non-nil on some platforms
createBIRDClient func(string) (wgengine.BIRDClient, error) // non-nil on some platforms
)
var subCommands = map[string]*func([]string) error{
"install-system-daemon": &installSystemDaemon,
"uninstall-system-daemon": &uninstallSystemDaemon,
"debug": &debugModeFunc,
"be-child": &beChildFunc,
}
var beCLI func() // non-nil if CLI is linked in
func main() {
envknob.PanicIfAnyEnvCheckedInInit()
envknob.ApplyDiskConfig()
printVersion := false
flag.IntVar(&args.verbose, "verbose", 0, "log verbosity level; 0 is default, 1 or higher are increasingly verbose")
flag.BoolVar(&args.cleanup, "cleanup", false, "clean up system state and exit")
flag.StringVar(&args.debug, "debug", "", "listen address ([ip]:port) of optional debug server")
flag.StringVar(&args.socksAddr, "socks5-server", "", `optional [ip]:port to run a SOCK5 server (e.g. "localhost:1080")`)
flag.StringVar(&args.httpProxyAddr, "outbound-http-proxy-listen", "", `optional [ip]:port to run an outbound HTTP proxy (e.g. "localhost:8080")`)
flag.StringVar(&args.tunname, "tun", defaultTunName(), `tunnel interface name; use "userspace-networking" (beta) to not use TUN`)
flag.Var(flagtype.PortValue(&args.port, defaultPort()), "port", "UDP port to listen on for WireGuard and peer-to-peer traffic; 0 means automatically select")
flag.StringVar(&args.statepath, "state", "", "absolute path of state file; use 'kube:<secret-name>' to use Kubernetes secrets or 'arn:aws:ssm:...' to store in AWS SSM; use 'mem:' to not store state and register as an ephemeral node. If empty and --statedir is provided, the default is <statedir>/tailscaled.state. Default: "+paths.DefaultTailscaledStateFile())
flag.StringVar(&args.statedir, "statedir", "", "path to directory for storage of config state, TLS certs, temporary incoming Taildrop files, etc. If empty, it's derived from --state when possible.")
flag.StringVar(&args.socketpath, "socket", paths.DefaultTailscaledSocket(), "path of the service unix socket")
flag.StringVar(&args.birdSocketPath, "bird-socket", "", "path of the bird unix socket")
flag.BoolVar(&printVersion, "version", false, "print version information and exit")
flag.BoolVar(&args.disableLogs, "no-logs-no-support", false, "disable log uploads; this also disables any technical support")
if len(os.Args) > 0 && filepath.Base(os.Args[0]) == "tailscale" && beCLI != nil {
beCLI()
return
}
if len(os.Args) > 1 {
sub := os.Args[1]
if fp, ok := subCommands[sub]; ok {
if *fp == nil {
log.SetFlags(0)
log.Fatalf("%s not available on %v", sub, runtime.GOOS)
}
if err := (*fp)(os.Args[2:]); err != nil {
log.SetFlags(0)
log.Fatal(err)
}
return
}
}
flag.Parse()
if flag.NArg() > 0 {
// Windows subprocess is spawned with /subprocess, so we need to avoid this check there.
if runtime.GOOS != "windows" || (flag.Arg(0) != "/subproc" && flag.Arg(0) != "/firewall") {
log.Fatalf("tailscaled does not take non-flag arguments: %q", flag.Args())
}
}
if printVersion {
fmt.Println(version.String())
os.Exit(0)
}
if runtime.GOOS == "darwin" && os.Getuid() != 0 && !strings.Contains(args.tunname, "userspace-networking") && !args.cleanup {
log.SetFlags(0)
log.Fatalf("tailscaled requires root; use sudo tailscaled (or use --tun=userspace-networking)")
}
if args.socketpath == "" && runtime.GOOS != "windows" {
log.SetFlags(0)
log.Fatalf("--socket is required")
}
if args.birdSocketPath != "" && createBIRDClient == nil {
log.SetFlags(0)
log.Fatalf("--bird-socket is not supported on %s", runtime.GOOS)
}
// Only apply a default statepath when neither have been provided, so that a
// user may specify only --statedir if they wish.
if args.statepath == "" && args.statedir == "" {
args.statepath = paths.DefaultTailscaledStateFile()
}
if args.disableLogs {
envknob.SetNoLogsNoSupport()
}
if beWindowsSubprocess() {
return
}
err := run()
// Remove file sharing from Windows shell (noop in non-windows)
osshare.SetFileSharingEnabled(false, logger.Discard)
if err != nil {
log.Fatal(err)
}
}
func trySynologyMigration(p string) error {
if runtime.GOOS != "linux" || distro.Get() != distro.Synology {
return nil
}
fi, err := os.Stat(p)
if err == nil && fi.Size() > 0 || !os.IsNotExist(err) {
return err
}
// File is empty or doesn't exist, try reading from the old path.
const oldPath = "/var/packages/Tailscale/etc/tailscaled.state"
if _, err := os.Stat(oldPath); err != nil {
if os.IsNotExist(err) {
return nil
}
return err
}
if err := os.Chown(oldPath, os.Getuid(), os.Getgid()); err != nil {
return err
}
if err := os.Rename(oldPath, p); err != nil {
return err
}
return nil
}
func statePathOrDefault() string {
if args.statepath != "" {
return args.statepath
}
if args.statedir != "" {
return filepath.Join(args.statedir, "tailscaled.state")
}
return ""
}
// serverOptions is the configuration of the Tailscale node agent.
type serverOptions struct {
// VarRoot is the Tailscale daemon's private writable
// directory (usually "/var/lib/tailscale" on Linux) that
// contains the "tailscaled.state" file, the "certs" directory
// for TLS certs, and the "files" directory for incoming
// Taildrop files before they're moved to a user directory.
// If empty, Taildrop and TLS certs don't function.
VarRoot string
// LoginFlags specifies the LoginFlags to pass to the client.
LoginFlags controlclient.LoginFlags
}
func ipnServerOpts() (o serverOptions) {
goos := envknob.GOOS()
o.VarRoot = args.statedir
// If an absolute --state is provided but not --statedir, try to derive
// a state directory.
if o.VarRoot == "" && filepath.IsAbs(args.statepath) {
if dir := filepath.Dir(args.statepath); strings.EqualFold(filepath.Base(dir), "tailscale") {
o.VarRoot = dir
}
}
if strings.HasPrefix(statePathOrDefault(), "mem:") {
// Register as an ephemeral node.
o.LoginFlags = controlclient.LoginEphemeral
}
switch goos {
case "js":
// The js/wasm client has no state storage so for now
// treat all interactive logins as ephemeral.
// TODO(bradfitz): if we start using browser LocalStorage
// or something, then rethink this.
o.LoginFlags = controlclient.LoginEphemeral
case "windows":
// Not those.
}
return o
}
var logPol *logpolicy.Policy
var debugMux *http.ServeMux
func run() error {
var logf logger.Logf = log.Printf
sys := new(tsd.System)
netMon, err := netmon.New(func(format string, args ...any) {
logf(format, args...)
})
if err != nil {
return fmt.Errorf("netmon.New: %w", err)
}
sys.Set(netMon)
pol := logpolicy.New(logtail.CollectionNode, netMon, nil /* use log.Printf */)
pol.SetVerbosityLevel(args.verbose)
logPol = pol
defer func() {
// Finish uploading logs after closing everything else.
ctx, cancel := context.WithTimeout(context.Background(), time.Second)
defer cancel()
pol.Shutdown(ctx)
}()
if err := envknob.ApplyDiskConfigError(); err != nil {
log.Printf("Error reading environment config: %v", err)
}
if isWindowsService() {
// Run the IPN server from the Windows service manager.
log.Printf("Running service...")
if err := runWindowsService(pol); err != nil {
log.Printf("runservice: %v", err)
}
log.Printf("Service ended.")
return nil
}
if envknob.Bool("TS_DEBUG_MEMORY") {
logf = logger.RusagePrefixLog(logf)
}
logf = logger.RateLimitedFn(logf, 5*time.Second, 5, 100)
if args.cleanup {
if envknob.Bool("TS_PLEASE_PANIC") {
panic("TS_PLEASE_PANIC asked us to panic")
}
dns.Cleanup(logf, args.tunname)
router.Cleanup(logf, args.tunname)
return nil
}
if args.statepath == "" && args.statedir == "" {
log.Fatalf("--statedir (or at least --state) is required")
}
if err := trySynologyMigration(statePathOrDefault()); err != nil {
log.Printf("error in synology migration: %v", err)
}
if args.debug != "" {
debugMux = newDebugMux()
}
return startIPNServer(context.Background(), logf, pol.PublicID, sys)
}
func startIPNServer(ctx context.Context, logf logger.Logf, logID logid.PublicID, sys *tsd.System) error {
ln, err := safesocket.Listen(args.socketpath)
if err != nil {
return fmt.Errorf("safesocket.Listen: %v", err)
}
ctx, cancel := context.WithCancel(ctx)
defer cancel()
// Exit gracefully by cancelling the ipnserver context in most common cases:
// interrupted from the TTY or killed by a service manager.
interrupt := make(chan os.Signal, 1)
signal.Notify(interrupt, syscall.SIGINT, syscall.SIGTERM)
// SIGPIPE sometimes gets generated when CLIs disconnect from
// tailscaled. The default action is to terminate the process, we
// want to keep running.
signal.Ignore(syscall.SIGPIPE)
go func() {
select {
case s := <-interrupt:
logf("tailscaled got signal %v; shutting down", s)
cancel()
case <-ctx.Done():
// continue
}
}()
srv := ipnserver.New(logf, logID, sys.NetMon.Get())
if debugMux != nil {
debugMux.HandleFunc("/debug/ipn", srv.ServeHTMLStatus)
}
var lbErr syncs.AtomicValue[error]
go func() {
t0 := time.Now()
if s, ok := envknob.LookupInt("TS_DEBUG_BACKEND_DELAY_SEC"); ok {
d := time.Duration(s) * time.Second
logf("sleeping %v before starting backend...", d)
select {
case <-time.After(d):
logf("slept %v; starting backend...", d)
case <-ctx.Done():
return
}
}
lb, err := getLocalBackend(ctx, logf, logID, sys)
if err == nil {
logf("got LocalBackend in %v", time.Since(t0).Round(time.Millisecond))
srv.SetLocalBackend(lb)
return
}
lbErr.Store(err) // before the following cancel
cancel() // make srv.Run below complete
}()
err = srv.Run(ctx, ln)
if err != nil && lbErr.Load() != nil {
return fmt.Errorf("getLocalBackend error: %v", lbErr.Load())
}
// Cancelation is not an error: it is the only way to stop ipnserver.
if err != nil && !errors.Is(err, context.Canceled) {
return fmt.Errorf("ipnserver.Run: %w", err)
}
return nil
}
func getLocalBackend(ctx context.Context, logf logger.Logf, logID logid.PublicID, sys *tsd.System) (_ *ipnlocal.LocalBackend, retErr error) {
if logPol != nil {
logPol.Logtail.SetNetMon(sys.NetMon.Get())
}
socksListener, httpProxyListener := mustStartProxyListeners(args.socksAddr, args.httpProxyAddr)
dialer := &tsdial.Dialer{Logf: logf} // mutated below (before used)
sys.Set(dialer)
onlyNetstack, err := createEngine(logf, sys)
if err != nil {
return nil, fmt.Errorf("createEngine: %w", err)
}
if debugMux != nil {
if ms, ok := sys.MagicSock.GetOK(); ok {
debugMux.HandleFunc("/debug/magicsock", ms.ServeHTTPDebug)
}
go runDebugServer(debugMux, args.debug)
}
ns, err := newNetstack(logf, sys)
if err != nil {
return nil, fmt.Errorf("newNetstack: %w", err)
}
ns.ProcessLocalIPs = onlyNetstack
ns.ProcessSubnets = onlyNetstack || handleSubnetsInNetstack()
if onlyNetstack {
e := sys.Engine.Get()
dialer.UseNetstackForIP = func(ip netip.Addr) bool {
_, ok := e.PeerForIP(ip)
return ok
}
dialer.NetstackDialTCP = func(ctx context.Context, dst netip.AddrPort) (net.Conn, error) {
return ns.DialContextTCP(ctx, dst)
}
}
if socksListener != nil || httpProxyListener != nil {
var addrs []string
if httpProxyListener != nil {
hs := &http.Server{Handler: httpProxyHandler(dialer.UserDial)}
go func() {
log.Fatalf("HTTP proxy exited: %v", hs.Serve(httpProxyListener))
}()
addrs = append(addrs, httpProxyListener.Addr().String())
}
if socksListener != nil {
ss := &socks5.Server{
Logf: logger.WithPrefix(logf, "socks5: "),
Dialer: dialer.UserDial,
}
go func() {
log.Fatalf("SOCKS5 server exited: %v", ss.Serve(socksListener))
}()
addrs = append(addrs, socksListener.Addr().String())
}
tshttpproxy.SetSelfProxy(addrs...)
}
opts := ipnServerOpts()
store, err := store.New(logf, statePathOrDefault())
if err != nil {
return nil, fmt.Errorf("store.New: %w", err)
}
sys.Set(store)
lb, err := ipnlocal.NewLocalBackend(logf, logID, sys, opts.LoginFlags)
if err != nil {
return nil, fmt.Errorf("ipnlocal.NewLocalBackend: %w", err)
}
lb.SetVarRoot(opts.VarRoot)
if logPol != nil {
lb.SetLogFlusher(logPol.Logtail.StartFlush)
}
if root := lb.TailscaleVarRoot(); root != "" {
dnsfallback.SetCachePath(filepath.Join(root, "derpmap.cached.json"), logf)
}
lb.SetDecompressor(func() (controlclient.Decompressor, error) {
return smallzstd.NewDecoder(nil)
})
configureTaildrop(logf, lb)
if err := ns.Start(lb); err != nil {
log.Fatalf("failed to start netstack: %v", err)
}
return lb, nil
}
// createEngine tries to the wgengine.Engine based on the order of tunnels
// specified in the command line flags.
//
// onlyNetstack is true if the user has explicitly requested that we use netstack
// for all networking.
func createEngine(logf logger.Logf, sys *tsd.System) (onlyNetstack bool, err error) {
if args.tunname == "" {
return false, errors.New("no --tun value specified")
}
var errs []error
for _, name := range strings.Split(args.tunname, ",") {
logf("wgengine.NewUserspaceEngine(tun %q) ...", name)
onlyNetstack, err = tryEngine(logf, sys, name)
if err == nil {
return onlyNetstack, nil
}
logf("wgengine.NewUserspaceEngine(tun %q) error: %v", name, err)
errs = append(errs, err)
}
return false, multierr.New(errs...)
}
// handleSubnetsInNetstack reports whether netstack should handle subnet routers
// as opposed to the OS. We do this if the OS doesn't support subnet routers
// (e.g. Windows) or if the user has explicitly requested it (e.g.
// --tun=userspace-networking).
func handleSubnetsInNetstack() bool {
if v, ok := envknob.LookupBool("TS_DEBUG_NETSTACK_SUBNETS"); ok {
return v
}
if distro.Get() == distro.Synology {
return true
}
switch runtime.GOOS {
case "windows", "darwin", "freebsd", "openbsd":
// Enable on Windows and tailscaled-on-macOS (this doesn't
// affect the GUI clients), and on FreeBSD.
return true
}
return false
}
var tstunNew = tstun.New
func tryEngine(logf logger.Logf, sys *tsd.System, name string) (onlyNetstack bool, err error) {
conf := wgengine.Config{
ListenPort: args.port,
NetMon: sys.NetMon.Get(),
Dialer: sys.Dialer.Get(),
SetSubsystem: sys.Set,
}
onlyNetstack = name == "userspace-networking"
netstackSubnetRouter := onlyNetstack // but mutated later on some platforms
netns.SetEnabled(!onlyNetstack)
if args.birdSocketPath != "" && createBIRDClient != nil {
log.Printf("Connecting to BIRD at %s ...", args.birdSocketPath)
conf.BIRDClient, err = createBIRDClient(args.birdSocketPath)
if err != nil {
return false, fmt.Errorf("createBIRDClient: %w", err)
}
}
if onlyNetstack {
if runtime.GOOS == "linux" && distro.Get() == distro.Synology {
// On Synology in netstack mode, still init a DNS
// manager (directManager) to avoid the health check
// warnings in 'tailscale status' about DNS base
// configuration being unavailable (from the noop
// manager). More in Issue 4017.
// TODO(bradfitz): add a Synology-specific DNS manager.
conf.DNS, err = dns.NewOSConfigurator(logf, "") // empty interface name
if err != nil {
return false, fmt.Errorf("dns.NewOSConfigurator: %w", err)
}
}
} else {
dev, devName, err := tstunNew(logf, name)
if err != nil {
tstun.Diagnose(logf, name, err)
return false, fmt.Errorf("tstun.New(%q): %w", name, err)
}
conf.Tun = dev
if strings.HasPrefix(name, "tap:") {
conf.IsTAP = true
e, err := wgengine.NewUserspaceEngine(logf, conf)
if err != nil {
return false, err
}
sys.Set(e)
return false, err
}
r, err := router.New(logf, dev, sys.NetMon.Get())
if err != nil {
dev.Close()
return false, fmt.Errorf("creating router: %w", err)
}
d, err := dns.NewOSConfigurator(logf, devName)
if err != nil {
dev.Close()
r.Close()
return false, fmt.Errorf("dns.NewOSConfigurator: %w", err)
}
conf.DNS = d
conf.Router = r
if handleSubnetsInNetstack() {
conf.Router = netstack.NewSubnetRouterWrapper(conf.Router)
netstackSubnetRouter = true
}
sys.Set(conf.Router)
}
e, err := wgengine.NewUserspaceEngine(logf, conf)
if err != nil {
return onlyNetstack, err
}
e = wgengine.NewWatchdog(e)
sys.Set(e)
sys.NetstackRouter.Set(netstackSubnetRouter)
return onlyNetstack, nil
}
func newDebugMux() *http.ServeMux {
mux := http.NewServeMux()
mux.HandleFunc("/debug/metrics", servePrometheusMetrics)
mux.HandleFunc("/debug/pprof/", pprof.Index)
mux.HandleFunc("/debug/pprof/cmdline", pprof.Cmdline)
mux.HandleFunc("/debug/pprof/profile", pprof.Profile)
mux.HandleFunc("/debug/pprof/symbol", pprof.Symbol)
mux.HandleFunc("/debug/pprof/trace", pprof.Trace)
return mux
}
func servePrometheusMetrics(w http.ResponseWriter, r *http.Request) {
w.Header().Set("Content-Type", "text/plain")
varz.Handler(w, r)
clientmetric.WritePrometheusExpositionFormat(w)
}
func runDebugServer(mux *http.ServeMux, addr string) {
srv := &http.Server{
Addr: addr,
Handler: mux,
}
if err := srv.ListenAndServe(); err != nil {
log.Fatal(err)
}
}
func newNetstack(logf logger.Logf, sys *tsd.System) (*netstack.Impl, error) {
return netstack.Create(logf, sys.Tun.Get(), sys.Engine.Get(), sys.MagicSock.Get(), sys.Dialer.Get(), sys.DNSManager.Get())
}
// mustStartProxyListeners creates listeners for local SOCKS and HTTP
// proxies, if the respective addresses are not empty. socksAddr and
// httpAddr can be the same, in which case socksListener will receive
// connections that look like they're speaking SOCKS and httpListener
// will receive everything else.
//
// socksListener and httpListener can be nil, if their respective
// addrs are empty.
func mustStartProxyListeners(socksAddr, httpAddr string) (socksListener, httpListener net.Listener) {
if socksAddr == httpAddr && socksAddr != "" && !strings.HasSuffix(socksAddr, ":0") {
ln, err := net.Listen("tcp", socksAddr)
if err != nil {
log.Fatalf("proxy listener: %v", err)
}
return proxymux.SplitSOCKSAndHTTP(ln)
}
var err error
if socksAddr != "" {
socksListener, err = net.Listen("tcp", socksAddr)
if err != nil {
log.Fatalf("SOCKS5 listener: %v", err)
}
if strings.HasSuffix(socksAddr, ":0") {
// Log kernel-selected port number so integration tests
// can find it portably.
log.Printf("SOCKS5 listening on %v", socksListener.Addr())
}
}
if httpAddr != "" {
httpListener, err = net.Listen("tcp", httpAddr)
if err != nil {
log.Fatalf("HTTP proxy listener: %v", err)
}
if strings.HasSuffix(httpAddr, ":0") {
// Log kernel-selected port number so integration tests
// can find it portably.
log.Printf("HTTP proxy listening on %v", httpListener.Addr())
}
}
return socksListener, httpListener
}
var beChildFunc = beChild
func beChild(args []string) error {
if len(args) == 0 {
return errors.New("missing mode argument")
}
typ := args[0]
f, ok := childproc.Code[typ]
if !ok {
return fmt.Errorf("unknown be-child mode %q", typ)
}
return f(args[1:])
}