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tailscale/tsnet/tsnet.go

594 lines
15 KiB
Go

// Copyright (c) Tailscale Inc & AUTHORS
// SPDX-License-Identifier: BSD-3-Clause
// Package tsnet provides Tailscale as a library.
//
// It is an experimental work in progress.
package tsnet
import (
"context"
"errors"
"fmt"
"io"
"log"
"math"
"net"
"net/http"
"net/netip"
"os"
"path/filepath"
"strings"
"sync"
"time"
"tailscale.com/client/tailscale"
"tailscale.com/control/controlclient"
"tailscale.com/envknob"
"tailscale.com/hostinfo"
"tailscale.com/ipn"
"tailscale.com/ipn/ipnlocal"
"tailscale.com/ipn/localapi"
"tailscale.com/ipn/store"
"tailscale.com/ipn/store/mem"
"tailscale.com/logpolicy"
"tailscale.com/logtail"
"tailscale.com/logtail/filch"
"tailscale.com/net/memnet"
"tailscale.com/net/tsdial"
"tailscale.com/smallzstd"
"tailscale.com/types/logger"
"tailscale.com/util/mak"
"tailscale.com/wgengine"
"tailscale.com/wgengine/monitor"
"tailscale.com/wgengine/netstack"
)
// Server is an embedded Tailscale server.
//
// Its exported fields may be changed until the first call to Listen.
type Server struct {
// Dir specifies the name of the directory to use for
// state. If empty, a directory is selected automatically
// under os.UserConfigDir (https://golang.org/pkg/os/#UserConfigDir).
// based on the name of the binary.
Dir string
// Store specifies the state store to use.
//
// If nil, a new FileStore is initialized at `Dir/tailscaled.state`.
// See tailscale.com/ipn/store for supported stores.
//
// Logs will automatically be uploaded to uploaded to log.tailscale.io,
// where the configuration file for logging will be saved at
// `Dir/tailscaled.log.conf`.
Store ipn.StateStore
// Hostname is the hostname to present to the control server.
// If empty, the binary name is used.
Hostname string
// Logf, if non-nil, specifies the logger to use. By default,
// log.Printf is used.
Logf logger.Logf
// Ephemeral, if true, specifies that the instance should register
// as an Ephemeral node (https://tailscale.com/kb/1111/ephemeral-nodes/).
Ephemeral bool
// AuthKey, if non-empty, is the auth key to create the node
// and will be preferred over the TS_AUTHKEY environment
// variable. If the node is already created (from state
// previously stored in in Store), then this field is not
// used.
AuthKey string
// ControlURL optionally specifies the coordination server URL.
// If empty, the Tailscale default is used.
ControlURL string
initOnce sync.Once
initErr error
lb *ipnlocal.LocalBackend
netstack *netstack.Impl
linkMon *monitor.Mon
localAPIListener net.Listener
rootPath string // the state directory
hostname string
shutdownCtx context.Context
shutdownCancel context.CancelFunc
localClient *tailscale.LocalClient
logbuffer *filch.Filch
logtail *logtail.Logger
mu sync.Mutex
listeners map[listenKey]*listener
dialer *tsdial.Dialer
}
// Dial connects to the address on the tailnet.
// It will start the server if it has not been started yet.
func (s *Server) Dial(ctx context.Context, network, address string) (net.Conn, error) {
if err := s.Start(); err != nil {
return nil, err
}
return s.dialer.UserDial(ctx, network, address)
}
// HTTPClient returns an HTTP client that is configured to connect over Tailscale.
//
// This is useful if you need to have your tsnet services connect to other devices on
// your tailnet.
func (s *Server) HTTPClient() *http.Client {
return &http.Client{
Transport: &http.Transport{
DialContext: s.Dial,
},
}
}
// LocalClient returns a LocalClient that speaks to s.
//
// It will start the server if it has not been started yet. If the server's
// already been started successfully, it doesn't return an error.
func (s *Server) LocalClient() (*tailscale.LocalClient, error) {
if err := s.Start(); err != nil {
return nil, err
}
return s.localClient, nil
}
// Start connects the server to the tailnet.
// Optional: any calls to Dial/Listen will also call Start.
func (s *Server) Start() error {
hostinfo.SetPackage("tsnet")
s.initOnce.Do(s.doInit)
return s.initErr
}
// Close stops the server.
//
// It must not be called before or concurrently with Start.
func (s *Server) Close() error {
ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
defer cancel()
var wg sync.WaitGroup
wg.Add(1)
go func() {
defer wg.Done()
// Perform a best-effort final flush.
s.logtail.Shutdown(ctx)
s.logbuffer.Close()
}()
if _, isMemStore := s.Store.(*mem.Store); isMemStore && s.Ephemeral {
wg.Add(1)
go func() {
defer wg.Done()
// Perform a best-effort logout.
s.lb.LogoutSync(ctx)
}()
}
if s.netstack != nil {
s.netstack.Close()
s.netstack = nil
}
s.shutdownCancel()
s.lb.Shutdown()
s.linkMon.Close()
s.dialer.Close()
s.localAPIListener.Close()
s.mu.Lock()
defer s.mu.Unlock()
for _, ln := range s.listeners {
ln.Close()
}
s.listeners = nil
wg.Wait()
return nil
}
func (s *Server) doInit() {
s.shutdownCtx, s.shutdownCancel = context.WithCancel(context.Background())
if err := s.start(); err != nil {
s.initErr = fmt.Errorf("tsnet: %w", err)
}
}
func (s *Server) getAuthKey() string {
if v := s.AuthKey; v != "" {
return v
}
return os.Getenv("TS_AUTHKEY")
}
func (s *Server) start() (reterr error) {
var closePool closeOnErrorPool
defer closePool.closeAllIfError(&reterr)
exe, err := os.Executable()
if err != nil {
return err
}
prog := strings.TrimSuffix(strings.ToLower(filepath.Base(exe)), ".exe")
s.hostname = s.Hostname
if s.hostname == "" {
s.hostname = prog
}
s.rootPath = s.Dir
if s.Store != nil {
_, isMemStore := s.Store.(*mem.Store)
if isMemStore && !s.Ephemeral {
return fmt.Errorf("in-memory store is only supported for Ephemeral nodes")
}
}
logf := s.logf
if s.rootPath == "" {
confDir, err := os.UserConfigDir()
if err != nil {
return err
}
s.rootPath, err = getTSNetDir(logf, confDir, prog)
if err != nil {
return err
}
if err := os.MkdirAll(s.rootPath, 0700); err != nil {
return err
}
}
if fi, err := os.Stat(s.rootPath); err != nil {
return err
} else if !fi.IsDir() {
return fmt.Errorf("%v is not a directory", s.rootPath)
}
cfgPath := filepath.Join(s.rootPath, "tailscaled.log.conf")
lpc, err := logpolicy.ConfigFromFile(cfgPath)
switch {
case os.IsNotExist(err):
lpc = logpolicy.NewConfig(logtail.CollectionNode)
if err := lpc.Save(cfgPath); err != nil {
return fmt.Errorf("logpolicy.Config.Save for %v: %w", cfgPath, err)
}
case err != nil:
return fmt.Errorf("logpolicy.LoadConfig for %v: %w", cfgPath, err)
}
if err := lpc.Validate(logtail.CollectionNode); err != nil {
return fmt.Errorf("logpolicy.Config.Validate for %v: %w", cfgPath, err)
}
logid := lpc.PublicID.String()
s.logbuffer, err = filch.New(filepath.Join(s.rootPath, "tailscaled"), filch.Options{ReplaceStderr: false})
if err != nil {
return fmt.Errorf("error creating filch: %w", err)
}
closePool.add(s.logbuffer)
c := logtail.Config{
Collection: lpc.Collection,
PrivateID: lpc.PrivateID,
Stderr: io.Discard, // log everything to Buffer
Buffer: s.logbuffer,
NewZstdEncoder: func() logtail.Encoder {
w, err := smallzstd.NewEncoder(nil)
if err != nil {
panic(err)
}
return w
},
HTTPC: &http.Client{Transport: logpolicy.NewLogtailTransport(logtail.DefaultHost)},
}
s.logtail = logtail.NewLogger(c, logf)
closePool.addFunc(func() { s.logtail.Shutdown(context.Background()) })
s.linkMon, err = monitor.New(logf)
if err != nil {
return err
}
closePool.add(s.linkMon)
s.dialer = &tsdial.Dialer{Logf: logf} // mutated below (before used)
eng, err := wgengine.NewUserspaceEngine(logf, wgengine.Config{
ListenPort: 0,
LinkMonitor: s.linkMon,
Dialer: s.dialer,
})
if err != nil {
return err
}
closePool.add(s.dialer)
tunDev, magicConn, dns, ok := eng.(wgengine.InternalsGetter).GetInternals()
if !ok {
return fmt.Errorf("%T is not a wgengine.InternalsGetter", eng)
}
ns, err := netstack.Create(logf, tunDev, eng, magicConn, s.dialer, dns)
if err != nil {
return fmt.Errorf("netstack.Create: %w", err)
}
ns.ProcessLocalIPs = true
ns.ForwardTCPIn = s.forwardTCP
s.netstack = ns
s.dialer.UseNetstackForIP = func(ip netip.Addr) bool {
_, ok := eng.PeerForIP(ip)
return ok
}
s.dialer.NetstackDialTCP = func(ctx context.Context, dst netip.AddrPort) (net.Conn, error) {
return ns.DialContextTCP(ctx, dst)
}
if s.Store == nil {
stateFile := filepath.Join(s.rootPath, "tailscaled.state")
logf("tsnet running state path %s", stateFile)
s.Store, err = store.New(logf, stateFile)
if err != nil {
return err
}
}
loginFlags := controlclient.LoginDefault
if s.Ephemeral {
loginFlags = controlclient.LoginEphemeral
}
lb, err := ipnlocal.NewLocalBackend(logf, logid, s.Store, "", s.dialer, eng, loginFlags)
if err != nil {
return fmt.Errorf("NewLocalBackend: %v", err)
}
lb.SetVarRoot(s.rootPath)
logf("tsnet starting with hostname %q, varRoot %q", s.hostname, s.rootPath)
s.lb = lb
if err := ns.Start(lb); err != nil {
return fmt.Errorf("failed to start netstack: %w", err)
}
closePool.addFunc(func() { s.lb.Shutdown() })
lb.SetDecompressor(func() (controlclient.Decompressor, error) {
return smallzstd.NewDecoder(nil)
})
prefs := ipn.NewPrefs()
prefs.Hostname = s.hostname
prefs.WantRunning = true
prefs.ControlURL = s.ControlURL
authKey := s.getAuthKey()
err = lb.Start(ipn.Options{
UpdatePrefs: prefs,
AuthKey: authKey,
})
if err != nil {
return fmt.Errorf("starting backend: %w", err)
}
st := lb.State()
if st == ipn.NeedsLogin || envknob.Bool("TSNET_FORCE_LOGIN") {
logf("LocalBackend state is %v; running StartLoginInteractive...", st)
s.lb.StartLoginInteractive()
} else if authKey != "" {
logf("Authkey is set; but state is %v. Ignoring authkey. Re-run with TSNET_FORCE_LOGIN=1 to force use of authkey.", st)
}
go s.printAuthURLLoop()
// Run the localapi handler, to allow fetching LetsEncrypt certs.
lah := localapi.NewHandler(lb, logf, logid)
lah.PermitWrite = true
lah.PermitRead = true
// Create an in-process listener.
// nettest.Listen provides a in-memory pipe based implementation for net.Conn.
lal := memnet.Listen("local-tailscaled.sock:80")
s.localAPIListener = lal
s.localClient = &tailscale.LocalClient{Dial: lal.Dial}
go func() {
if err := http.Serve(lal, lah); err != nil {
logf("localapi serve error: %v", err)
}
}()
closePool.add(s.localAPIListener)
return nil
}
type closeOnErrorPool []func()
func (p *closeOnErrorPool) add(c io.Closer) { *p = append(*p, func() { c.Close() }) }
func (p *closeOnErrorPool) addFunc(fn func()) { *p = append(*p, fn) }
func (p closeOnErrorPool) closeAllIfError(errp *error) {
if *errp != nil {
for _, closeFn := range p {
closeFn()
}
}
}
func (s *Server) logf(format string, a ...interface{}) {
if s.logtail != nil {
s.logtail.Logf(format, a...)
}
if s.Logf != nil {
s.Logf(format, a...)
return
}
log.Printf(format, a...)
}
// printAuthURLLoop loops once every few seconds while the server is still running and
// is in NeedsLogin state, printing out the auth URL.
func (s *Server) printAuthURLLoop() {
for {
if s.shutdownCtx.Err() != nil {
return
}
if st := s.lb.State(); st != ipn.NeedsLogin {
s.logf("printAuthURLLoop: state is %v; stopping", st)
return
}
st := s.lb.StatusWithoutPeers()
if st.AuthURL != "" {
s.logf("To start this tsnet server, restart with TS_AUTHKEY set, or go to: %s", st.AuthURL)
}
select {
case <-time.After(5 * time.Second):
case <-s.shutdownCtx.Done():
return
}
}
}
func (s *Server) forwardTCP(c net.Conn, port uint16) {
s.mu.Lock()
ln, ok := s.listeners[listenKey{"tcp", "", port}]
s.mu.Unlock()
if !ok {
c.Close()
return
}
t := time.NewTimer(time.Second)
defer t.Stop()
select {
case ln.conn <- c:
case <-t.C:
c.Close()
}
}
// getTSNetDir usually just returns filepath.Join(confDir, "tsnet-"+prog)
// with no error.
//
// One special case is that it renames old "tslib-" directories to
// "tsnet-", and that rename might return an error.
//
// TODO(bradfitz): remove this maybe 6 months after 2022-03-17,
// once people (notably Tailscale corp services) have updated.
func getTSNetDir(logf logger.Logf, confDir, prog string) (string, error) {
oldPath := filepath.Join(confDir, "tslib-"+prog)
newPath := filepath.Join(confDir, "tsnet-"+prog)
fi, err := os.Lstat(oldPath)
if os.IsNotExist(err) {
// Common path.
return newPath, nil
}
if err != nil {
return "", err
}
if !fi.IsDir() {
return "", fmt.Errorf("expected old tslib path %q to be a directory; got %v", oldPath, fi.Mode())
}
// At this point, oldPath exists and is a directory. But does
// the new path exist?
fi, err = os.Lstat(newPath)
if err == nil && fi.IsDir() {
// New path already exists somehow. Ignore the old one and
// don't try to migrate it.
return newPath, nil
}
if err != nil && !os.IsNotExist(err) {
return "", err
}
if err := os.Rename(oldPath, newPath); err != nil {
return "", err
}
logf("renamed old tsnet state storage directory %q to %q", oldPath, newPath)
return newPath, nil
}
// APIClient returns a tailscale.Client that can be used to make authenticated
// requests to the Tailscale control server.
// It requires the user to set tailscale.I_Acknowledge_This_API_Is_Unstable.
func (s *Server) APIClient() (*tailscale.Client, error) {
if !tailscale.I_Acknowledge_This_API_Is_Unstable {
return nil, errors.New("use of Client without setting I_Acknowledge_This_API_Is_Unstable")
}
if err := s.Start(); err != nil {
return nil, err
}
c := tailscale.NewClient("-", nil)
c.HTTPClient = &http.Client{Transport: s.lb.KeyProvingNoiseRoundTripper()}
return c, nil
}
// Listen announces only on the Tailscale network.
// It will start the server if it has not been started yet.
func (s *Server) Listen(network, addr string) (net.Listener, error) {
switch network {
case "", "tcp", "tcp4", "tcp6":
default:
return nil, errors.New("unsupported network type")
}
host, portStr, err := net.SplitHostPort(addr)
if err != nil {
return nil, fmt.Errorf("tsnet: %w", err)
}
port, err := net.LookupPort(network, portStr)
if err != nil || port < 0 || port > math.MaxUint16 {
return nil, fmt.Errorf("invalid port: %w", err)
}
if err := s.Start(); err != nil {
return nil, err
}
key := listenKey{network, host, uint16(port)}
ln := &listener{
s: s,
key: key,
addr: addr,
conn: make(chan net.Conn),
}
s.mu.Lock()
if _, ok := s.listeners[key]; ok {
s.mu.Unlock()
return nil, fmt.Errorf("tsnet: listener already open for %s, %s", network, addr)
}
mak.Set(&s.listeners, key, ln)
s.mu.Unlock()
return ln, nil
}
type listenKey struct {
network string
host string
port uint16
}
type listener struct {
s *Server
key listenKey
addr string
conn chan net.Conn
}
func (ln *listener) Accept() (net.Conn, error) {
c, ok := <-ln.conn
if !ok {
return nil, fmt.Errorf("tsnet: %w", net.ErrClosed)
}
return c, nil
}
func (ln *listener) Addr() net.Addr { return addr{ln} }
func (ln *listener) Close() error {
ln.s.mu.Lock()
defer ln.s.mu.Unlock()
if v, ok := ln.s.listeners[ln.key]; ok && v == ln {
delete(ln.s.listeners, ln.key)
close(ln.conn)
}
return nil
}
// Server returns the tsnet Server associated with the listener.
func (ln *listener) Server() *Server { return ln.s }
type addr struct{ ln *listener }
func (a addr) Network() string { return a.ln.key.network }
func (a addr) String() string { return a.ln.addr }