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tailscale/tsnet/tsnet.go

1227 lines
34 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"
crand "crypto/rand"
"crypto/tls"
"encoding/hex"
"errors"
"fmt"
"io"
"log"
"math"
"net"
"net/http"
"net/netip"
"os"
"path/filepath"
"runtime"
"slices"
"strconv"
"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/ipnstate"
"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/netmon"
"tailscale.com/net/proxymux"
"tailscale.com/net/socks5"
"tailscale.com/net/tsdial"
"tailscale.com/smallzstd"
"tailscale.com/tsd"
"tailscale.com/types/logger"
"tailscale.com/types/logid"
"tailscale.com/types/nettype"
"tailscale.com/util/clientmetric"
"tailscale.com/util/mak"
"tailscale.com/util/set"
"tailscale.com/util/testenv"
"tailscale.com/wgengine"
"tailscale.com/wgengine/netstack"
)
// Server is an embedded Tailscale server.
//
// Its exported fields may be changed until the first method call.
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.
//
// If you want to use multiple tsnet services in the same
// binary, you will need to make sure that Dir is set uniquely
// for each service. A good pattern for this is to have a
// "base" directory (such as your mutable storage folder) and
// then append the hostname on the end of it.
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 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/s/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
// RunWebClient, if true, runs a client for managing this node over
// its Tailscale interface on port 5252.
RunWebClient bool
// Port is the UDP port to listen on for WireGuard and peer-to-peer
// traffic. If zero, a port is automatically selected. Leave this
// field at zero unless you know what you are doing.
Port uint16
getCertForTesting func(*tls.ClientHelloInfo) (*tls.Certificate, error)
initOnce sync.Once
initErr error
lb *ipnlocal.LocalBackend
netstack *netstack.Impl
netMon *netmon.Monitor
rootPath string // the state directory
hostname string
shutdownCtx context.Context
shutdownCancel context.CancelFunc
proxyCred string // SOCKS5 proxy auth for loopbackListener
localAPICred string // basic auth password for loopbackListener
loopbackListener net.Listener // optional loopback for localapi and proxies
localAPIListener net.Listener // in-memory, used by localClient
localClient *tailscale.LocalClient // in-memory
localAPIServer *http.Server
logbuffer *filch.Filch
logtail *logtail.Logger
logid logid.PublicID
mu sync.Mutex
listeners map[listenKey]*listener
fallbackTCPHandlers set.HandleSet[FallbackTCPHandler]
dialer *tsdial.Dialer
closed bool
}
// FallbackTCPHandler describes the callback which
// conditionally handles an incoming TCP flow for the
// provided (src/port, dst/port) 4-tuple. These are registered
// as handlers of last resort, and are called only if no
// listener could handle the incoming flow.
//
// If the callback returns intercept=false, the flow is rejected.
//
// When intercept=true, the behavior depends on whether the returned handler
// is non-nil: if nil, the connection is rejected. If non-nil, handler takes
// over the TCP conn.
type FallbackTCPHandler func(src, dst netip.AddrPort) (handler func(net.Conn), intercept bool)
// 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
}
// Loopback starts a routing server on a loopback address.
//
// The server has multiple functions.
//
// It can be used as a SOCKS5 proxy onto the tailnet.
// Authentication is required with the username "tsnet" and
// the value of proxyCred used as the password.
//
// The HTTP server also serves out the "LocalAPI" on /localapi.
// As the LocalAPI is powerful, access to endpoints requires BOTH passing a
// "Sec-Tailscale: localapi" HTTP header and passing localAPICred as basic auth.
//
// If you only need to use the LocalAPI from Go, then prefer LocalClient
// as it does not require communication via TCP.
func (s *Server) Loopback() (addr string, proxyCred, localAPICred string, err error) {
if err := s.Start(); err != nil {
return "", "", "", err
}
if s.loopbackListener == nil {
var proxyCred [16]byte
if _, err := crand.Read(proxyCred[:]); err != nil {
return "", "", "", err
}
s.proxyCred = hex.EncodeToString(proxyCred[:])
var cred [16]byte
if _, err := crand.Read(cred[:]); err != nil {
return "", "", "", err
}
s.localAPICred = hex.EncodeToString(cred[:])
ln, err := net.Listen("tcp", "127.0.0.1:0")
if err != nil {
return "", "", "", err
}
s.loopbackListener = ln
socksLn, httpLn := proxymux.SplitSOCKSAndHTTP(ln)
// TODO: add HTTP proxy support. Probably requires factoring
// out the CONNECT code from tailscaled/proxy.go that uses
// httputil.ReverseProxy and adding auth support.
go func() {
lah := localapi.NewHandler(s.lb, s.logf, s.netMon, s.logid)
lah.PermitWrite = true
lah.PermitRead = true
lah.RequiredPassword = s.localAPICred
h := &localSecHandler{h: lah, cred: s.localAPICred}
if err := http.Serve(httpLn, h); err != nil {
s.logf("localapi tcp serve error: %v", err)
}
}()
s5s := &socks5.Server{
Logf: logger.WithPrefix(s.logf, "socks5: "),
Dialer: s.dialer.UserDial,
Username: "tsnet",
Password: s.proxyCred,
}
go func() {
s.logf("SOCKS5 server exited: %v", s5s.Serve(socksLn))
}()
}
lbAddr := s.loopbackListener.Addr()
if lbAddr == nil {
// https://github.com/tailscale/tailscale/issues/7488
panic("loopbackListener has no Addr")
}
return lbAddr.String(), s.proxyCred, s.localAPICred, nil
}
type localSecHandler struct {
h http.Handler
cred string
}
func (h *localSecHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
if r.Header.Get("Sec-Tailscale") != "localapi" {
w.WriteHeader(403)
io.WriteString(w, "missing 'Sec-Tailscale: localapi' header")
return
}
h.h.ServeHTTP(w, r)
}
// 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
}
// Up connects the server to the tailnet and waits until it is running.
// On success it returns the current status, including a Tailscale IP address.
func (s *Server) Up(ctx context.Context) (*ipnstate.Status, error) {
lc, err := s.LocalClient() // calls Start
if err != nil {
return nil, fmt.Errorf("tsnet.Up: %w", err)
}
watcher, err := lc.WatchIPNBus(ctx, ipn.NotifyInitialState|ipn.NotifyNoPrivateKeys)
if err != nil {
return nil, fmt.Errorf("tsnet.Up: %w", err)
}
defer watcher.Close()
for {
n, err := watcher.Next()
if err != nil {
return nil, fmt.Errorf("tsnet.Up: %w", err)
}
if n.ErrMessage != nil {
return nil, fmt.Errorf("tsnet.Up: backend: %s", *n.ErrMessage)
}
if s := n.State; s != nil {
if *s == ipn.Running {
status, err := lc.Status(ctx)
if err != nil {
return nil, fmt.Errorf("tsnet.Up: %w", err)
}
if len(status.TailscaleIPs) == 0 {
return nil, errors.New("tsnet.Up: running, but no ip")
}
// Clear the persisted serve config state to prevent stale configuration
// from code changes. This is a temporary workaround until we have a better
// way to handle this. (2023-03-11)
if err := lc.SetServeConfig(ctx, new(ipn.ServeConfig)); err != nil {
return nil, fmt.Errorf("tsnet.Up: %w", err)
}
return status, nil
}
// TODO: in the future, return an error on ipn.NeedsLogin
// and ipn.NeedsMachineAuth to improve the UX of trying
// out the tsnet package.
//
// Unfortunately today, even when using an AuthKey we
// briefly see these states. It would be nice to fix.
}
}
}
// Close stops the server.
//
// It must not be called before or concurrently with Start.
func (s *Server) Close() error {
s.mu.Lock()
defer s.mu.Unlock()
if s.closed {
return fmt.Errorf("tsnet: %w", net.ErrClosed)
}
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.
if s.logtail != nil {
s.logtail.Shutdown(ctx)
}
if s.logbuffer != nil {
s.logbuffer.Close()
}
}()
wg.Add(1)
go func() {
defer wg.Done()
if s.localAPIServer != nil {
s.localAPIServer.Shutdown(ctx)
}
}()
if s.netstack != nil {
s.netstack.Close()
s.netstack = nil
}
if s.shutdownCancel != nil {
s.shutdownCancel()
}
if s.lb != nil {
s.lb.Shutdown()
}
if s.netMon != nil {
s.netMon.Close()
}
if s.dialer != nil {
s.dialer.Close()
}
if s.localAPIListener != nil {
s.localAPIListener.Close()
}
if s.loopbackListener != nil {
s.loopbackListener.Close()
}
for _, ln := range s.listeners {
ln.closeLocked()
}
wg.Wait()
s.closed = true
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)
}
}
// CertDomains returns the list of domains for which the server can
// provide TLS certificates. These are also the DNS names for the
// Server.
// If the server is not running, it returns nil.
func (s *Server) CertDomains() []string {
nm := s.lb.NetMap()
if nm == nil {
return nil
}
return slices.Clone(nm.DNS.CertDomains)
}
// TailscaleIPs returns IPv4 and IPv6 addresses for this node. If the node
// has not yet joined a tailnet or is otherwise unaware of its own IP addresses,
// the returned ip4, ip6 will be !netip.IsValid().
func (s *Server) TailscaleIPs() (ip4, ip6 netip.Addr) {
nm := s.lb.NetMap()
if nm == nil {
return
}
addrs := nm.GetAddresses()
for i := range addrs.Len() {
addr := addrs.At(i)
ip := addr.Addr()
if ip.Is6() {
ip6 = ip
}
if ip.Is4() {
ip4 = ip
}
}
return ip4, ip6
}
func (s *Server) getAuthKey() string {
if v := s.AuthKey; v != "" {
return v
}
if v := os.Getenv("TS_AUTHKEY"); v != "" {
return v
}
return os.Getenv("TS_AUTH_KEY")
}
func (s *Server) start() (reterr error) {
var closePool closeOnErrorPool
defer closePool.closeAllIfError(&reterr)
exe, err := os.Executable()
if err != nil {
switch runtime.GOOS {
case "js", "wasip1":
// These platforms don't implement os.Executable (at least as of Go
// 1.21), but we don't really care much: it's only used as a default
// directory and hostname when they're not supplied. But we can fall
// back to "tsnet" as well.
exe = "tsnet"
default:
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)
}
if err := s.startLogger(&closePool); err != nil {
return err
}
s.netMon, err = netmon.New(logf)
if err != nil {
return err
}
closePool.add(s.netMon)
sys := new(tsd.System)
s.dialer = &tsdial.Dialer{Logf: logf} // mutated below (before used)
eng, err := wgengine.NewUserspaceEngine(logf, wgengine.Config{
ListenPort: s.Port,
NetMon: s.netMon,
Dialer: s.dialer,
SetSubsystem: sys.Set,
ControlKnobs: sys.ControlKnobs(),
})
if err != nil {
return err
}
closePool.add(s.dialer)
sys.Set(eng)
// TODO(oxtoacart): do we need to support TailFS on tsnet, and if so, how?
ns, err := netstack.Create(logf, sys.Tun.Get(), eng, sys.MagicSock.Get(), s.dialer, sys.DNSManager.Get(), sys.ProxyMapper(), nil)
if err != nil {
return fmt.Errorf("netstack.Create: %w", err)
}
sys.Tun.Get().Start()
sys.Set(ns)
ns.ProcessLocalIPs = true
ns.ProcessSubnets = true
ns.GetTCPHandlerForFlow = s.getTCPHandlerForFlow
ns.GetUDPHandlerForFlow = s.getUDPHandlerForFlow
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) {
// Note: don't just return ns.DialContextTCP or we'll
// return an interface containing a nil pointer.
tcpConn, err := ns.DialContextTCP(ctx, dst)
if err != nil {
return nil, err
}
return tcpConn, nil
}
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
}
}
sys.Set(s.Store)
loginFlags := controlclient.LoginDefault
if s.Ephemeral {
loginFlags = controlclient.LoginEphemeral
}
lb, err := ipnlocal.NewLocalBackend(logf, s.logid, sys, loginFlags|controlclient.LocalBackendStartKeyOSNeutral)
if err != nil {
return fmt.Errorf("NewLocalBackend: %v", err)
}
lb.SetTCPHandlerForFunnelFlow(s.getTCPHandlerForFunnelFlow)
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() })
prefs := ipn.NewPrefs()
prefs.Hostname = s.hostname
prefs.WantRunning = true
prefs.ControlURL = s.ControlURL
prefs.RunWebClient = s.RunWebClient
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, s.netMon, s.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}
s.localAPIServer = &http.Server{Handler: lah}
s.lb.ConfigureWebClient(s.localClient)
go func() {
if err := s.localAPIServer.Serve(lal); err != nil {
logf("localapi serve error: %v", err)
}
}()
closePool.add(s.localAPIListener)
return nil
}
func (s *Server) startLogger(closePool *closeOnErrorPool) error {
if testenv.InTest() {
return nil
}
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)
}
s.logid = lpc.PublicID
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.netMon, s.logf)},
MetricsDelta: clientmetric.EncodeLogTailMetricsDelta,
}
s.logtail = logtail.NewLogger(c, s.logf)
closePool.addFunc(func() { s.logtail.Shutdown(context.Background()) })
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 ...any) {
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
}
}
}
// networkForFamily returns one of "tcp4", "tcp6", "udp4", or "udp6".
//
// netBase is "tcp" or "udp" (without any '4' or '6' suffix).
func networkForFamily(netBase string, is6 bool) string {
switch netBase {
case "tcp":
if is6 {
return "tcp6"
}
return "tcp4"
case "udp":
if is6 {
return "udp6"
}
return "udp4"
}
panic("unexpected")
}
// listenerForDstAddr returns a listener for the provided network and
// destination IP/port. It matches from most specific to least specific.
// For example:
//
// - ("tcp4", IP, port)
// - ("tcp", IP, port)
// - ("tcp4", "", port)
// - ("tcp", "", port)
//
// The netBase is "tcp" or "udp" (without any '4' or '6' suffix).
//
// Listeners which do not specify an IP address will match for traffic
// for the local node (that is, a destination address of the IPv4 or
// IPv6 address of this node) only. To listen for traffic on other addresses
// such as those routed inbound via subnet routes, explicitly specify
// the listening address or use RegisterFallbackTCPHandler.
func (s *Server) listenerForDstAddr(netBase string, dst netip.AddrPort, funnel bool) (_ *listener, ok bool) {
s.mu.Lock()
defer s.mu.Unlock()
// Search for a listener with the specified IP
for _, net := range [2]string{
networkForFamily(netBase, dst.Addr().Is6()),
netBase,
} {
if ln, ok := s.listeners[listenKey{net, dst.Addr(), dst.Port(), funnel}]; ok {
return ln, true
}
}
// Search for a listener without an IP if the destination was
// one of the native IPs of the node.
if ip4, ip6 := s.TailscaleIPs(); dst.Addr() == ip4 || dst.Addr() == ip6 {
for _, net := range [2]string{
networkForFamily(netBase, dst.Addr().Is6()),
netBase,
} {
if ln, ok := s.listeners[listenKey{net, netip.Addr{}, dst.Port(), funnel}]; ok {
return ln, true
}
}
}
return nil, false
}
func (s *Server) getTCPHandlerForFunnelFlow(src netip.AddrPort, dstPort uint16) (handler func(net.Conn)) {
ipv4, ipv6 := s.TailscaleIPs()
var dst netip.AddrPort
if src.Addr().Is4() {
if !ipv4.IsValid() {
return nil
}
dst = netip.AddrPortFrom(ipv4, dstPort)
} else {
if !ipv6.IsValid() {
return nil
}
dst = netip.AddrPortFrom(ipv6, dstPort)
}
ln, ok := s.listenerForDstAddr("tcp", dst, true)
if !ok {
return nil
}
return ln.handle
}
func (s *Server) getTCPHandlerForFlow(src, dst netip.AddrPort) (handler func(net.Conn), intercept bool) {
ln, ok := s.listenerForDstAddr("tcp", dst, false)
if !ok {
s.mu.Lock()
defer s.mu.Unlock()
for _, handler := range s.fallbackTCPHandlers {
connHandler, intercept := handler(src, dst)
if intercept {
return connHandler, intercept
}
}
return nil, true // don't handle, don't forward to localhost
}
return ln.handle, true
}
func (s *Server) getUDPHandlerForFlow(src, dst netip.AddrPort) (handler func(nettype.ConnPacketConn), intercept bool) {
ln, ok := s.listenerForDstAddr("udp", dst, false)
if !ok {
return nil, true // don't handle, don't forward to localhost
}
return func(c nettype.ConnPacketConn) { ln.handle(c) }, true
}
// 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.
//
// Listeners which do not specify an IP address will match for traffic
// for the local node (that is, a destination address of the IPv4 or
// IPv6 address of this node) only. To listen for traffic on other addresses
// such as those routed inbound via subnet routes, explicitly specify
// the listening address or use RegisterFallbackTCPHandler.
func (s *Server) Listen(network, addr string) (net.Listener, error) {
return s.listen(network, addr, listenOnTailnet)
}
// ListenTLS announces only on the Tailscale network.
// It returns a TLS listener wrapping the tsnet listener.
// It will start the server if it has not been started yet.
func (s *Server) ListenTLS(network, addr string) (net.Listener, error) {
if network != "tcp" {
return nil, fmt.Errorf("ListenTLS(%q, %q): only tcp is supported", network, addr)
}
ctx := context.Background()
st, err := s.Up(ctx)
if err != nil {
return nil, err
}
if len(st.CertDomains) == 0 {
return nil, errors.New("tsnet: you must enable HTTPS in the admin panel to proceed. See https://tailscale.com/s/https")
}
ln, err := s.listen(network, addr, listenOnTailnet)
if err != nil {
return nil, err
}
return tls.NewListener(ln, &tls.Config{
GetCertificate: s.getCert,
}), nil
}
// RegisterFallbackTCPHandler registers a callback which will be called
// to handle a TCP flow to this tsnet node, for which no listeners will handle.
//
// If multiple fallback handlers are registered, they will be called in an
// undefined order. See FallbackTCPHandler for details on handling a flow.
//
// The returned function can be used to deregister this callback.
func (s *Server) RegisterFallbackTCPHandler(cb FallbackTCPHandler) func() {
s.mu.Lock()
defer s.mu.Unlock()
hnd := s.fallbackTCPHandlers.Add(cb)
return func() {
s.mu.Lock()
defer s.mu.Unlock()
delete(s.fallbackTCPHandlers, hnd)
}
}
// getCert is the GetCertificate function used by ListenTLS.
//
// It calls GetCertificate on the localClient, passing in the ClientHelloInfo.
// For testing, if s.getCertForTesting is set, it will call that instead.
func (s *Server) getCert(hi *tls.ClientHelloInfo) (*tls.Certificate, error) {
if s.getCertForTesting != nil {
return s.getCertForTesting(hi)
}
lc, err := s.LocalClient()
if err != nil {
return nil, err
}
return lc.GetCertificate(hi)
}
// FunnelOption is an option passed to ListenFunnel to configure the listener.
type FunnelOption interface {
funnelOption()
}
type funnelOnly int
func (funnelOnly) funnelOption() {}
// FunnelOnly configures the listener to only respond to connections from Tailscale Funnel.
// The local tailnet will not be able to connect to the listener.
func FunnelOnly() FunnelOption { return funnelOnly(1) }
// ListenFunnel announces on the public internet using Tailscale Funnel.
//
// It also by default listens on your local tailnet, so connections can
// come from either inside or outside your network. To restrict connections
// to be just from the internet, use the FunnelOnly option.
//
// Currently (2023-03-10), Funnel only supports TCP on ports 443, 8443, and 10000.
// The supported host name is limited to that configured for the tsnet.Server.
// As such, the standard way to create funnel is:
//
// s.ListenFunnel("tcp", ":443")
//
// and the only other supported addrs currently are ":8443" and ":10000".
//
// It will start the server if it has not been started yet.
func (s *Server) ListenFunnel(network, addr string, opts ...FunnelOption) (net.Listener, error) {
if network != "tcp" {
return nil, fmt.Errorf("ListenFunnel(%q, %q): only tcp is supported", network, addr)
}
host, portStr, err := net.SplitHostPort(addr)
if err != nil {
return nil, err
}
if host != "" {
return nil, fmt.Errorf("ListenFunnel(%q, %q): host must be empty", network, addr)
}
port, err := strconv.ParseUint(portStr, 10, 16)
if err != nil {
return nil, err
}
ctx := context.Background()
st, err := s.Up(ctx)
if err != nil {
return nil, err
}
// TODO(sonia,tailscale/corp#10577): We may want to use the interactive enable
// flow here instead of CheckFunnelAccess to allow the user to turn on Funnel
// if not already on. Specifically when running from a terminal.
// See cli.serveEnv.verifyFunnelEnabled.
if err := ipn.CheckFunnelAccess(uint16(port), st.Self); err != nil {
return nil, err
}
lc := s.localClient
// May not have funnel enabled. Enable it.
srvConfig, err := lc.GetServeConfig(ctx)
if err != nil {
return nil, err
}
if srvConfig == nil {
srvConfig = &ipn.ServeConfig{}
}
if len(st.CertDomains) == 0 {
return nil, errors.New("Funnel not available; HTTPS must be enabled. See https://tailscale.com/s/https")
}
domain := st.CertDomains[0]
hp := ipn.HostPort(domain + ":" + portStr)
if !srvConfig.AllowFunnel[hp] {
mak.Set(&srvConfig.AllowFunnel, hp, true)
srvConfig.AllowFunnel[hp] = true
if err := lc.SetServeConfig(ctx, srvConfig); err != nil {
return nil, err
}
}
// Start a funnel listener.
lnOn := listenOnBoth
for _, opt := range opts {
if _, ok := opt.(funnelOnly); ok {
lnOn = listenOnFunnel
}
}
ln, err := s.listen(network, addr, lnOn)
if err != nil {
return nil, err
}
return tls.NewListener(ln, &tls.Config{
GetCertificate: s.getCert,
}), nil
}
type listenOn string
const (
listenOnTailnet = listenOn("listen-on-tailnet")
listenOnFunnel = listenOn("listen-on-funnel")
listenOnBoth = listenOn("listen-on-both")
)
func (s *Server) listen(network, addr string, lnOn listenOn) (net.Listener, error) {
switch network {
case "", "tcp", "tcp4", "tcp6", "udp", "udp4", "udp6":
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 {
// LookupPort returns an error on out of range values so the bounds
// checks on port should be unnecessary, but harmless. If they do
// match, worst case this error message says "invalid port: <nil>".
return nil, fmt.Errorf("invalid port: %w", err)
}
var bindHostOrZero netip.Addr
if host != "" {
bindHostOrZero, err = netip.ParseAddr(host)
if err != nil {
return nil, fmt.Errorf("invalid Listen addr %q; host part must be empty or IP literal", host)
}
if strings.HasSuffix(network, "4") && !bindHostOrZero.Is4() {
return nil, fmt.Errorf("invalid non-IPv4 addr %v for network %q", host, network)
}
if strings.HasSuffix(network, "6") && !bindHostOrZero.Is6() {
return nil, fmt.Errorf("invalid non-IPv6 addr %v for network %q", host, network)
}
}
if err := s.Start(); err != nil {
return nil, err
}
var keys []listenKey
switch lnOn {
case listenOnTailnet:
keys = append(keys, listenKey{network, bindHostOrZero, uint16(port), false})
case listenOnFunnel:
keys = append(keys, listenKey{network, bindHostOrZero, uint16(port), true})
case listenOnBoth:
keys = append(keys, listenKey{network, bindHostOrZero, uint16(port), false})
keys = append(keys, listenKey{network, bindHostOrZero, uint16(port), true})
}
ln := &listener{
s: s,
keys: keys,
addr: addr,
conn: make(chan net.Conn),
}
s.mu.Lock()
for _, key := range keys {
if _, ok := s.listeners[key]; ok {
s.mu.Unlock()
return nil, fmt.Errorf("tsnet: listener already open for %s, %s", network, addr)
}
}
if s.listeners == nil {
s.listeners = make(map[listenKey]*listener)
}
for _, key := range keys {
s.listeners[key] = ln
}
s.mu.Unlock()
return ln, nil
}
// CapturePcap can be called by the application code compiled with tsnet to save a pcap
// of packets which the netstack within tsnet sees. This is expected to be useful during
// debugging, probably not useful for production.
//
// Packets will be written to the pcap until the process exits. The pcap needs a Lua dissector
// to be installed in WireShark in order to decode properly: wgengine/capture/ts-dissector.lua
// in this repository.
// https://tailscale.com/kb/1023/troubleshooting/#can-i-examine-network-traffic-inside-the-encrypted-tunnel
func (s *Server) CapturePcap(ctx context.Context, pcapFile string) error {
stream, err := s.localClient.StreamDebugCapture(ctx)
if err != nil {
return err
}
f, err := os.OpenFile(pcapFile, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0644)
if err != nil {
stream.Close()
return err
}
go func(stream io.ReadCloser, f *os.File) {
defer stream.Close()
defer f.Close()
_, _ = io.Copy(f, stream)
}(stream, f)
return nil
}
type listenKey struct {
network string
host netip.Addr // or zero value for unspecified
port uint16
funnel bool
}
type listener struct {
s *Server
keys []listenKey
addr string
conn chan net.Conn
closed bool // guarded by s.mu
}
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()
return ln.closeLocked()
}
// closeLocked closes the listener.
// It must be called with ln.s.mu held.
func (ln *listener) closeLocked() error {
if ln.closed {
return fmt.Errorf("tsnet: %w", net.ErrClosed)
}
for _, key := range ln.keys {
if v, ok := ln.s.listeners[key]; ok && v == ln {
delete(ln.s.listeners, key)
}
}
close(ln.conn)
ln.closed = true
return nil
}
func (ln *listener) handle(c net.Conn) {
t := time.NewTimer(time.Second)
defer t.Stop()
select {
case ln.conn <- c:
case <-t.C:
// TODO(bradfitz): this isn't ideal. Think about how
// we how we want to do pushback.
c.Close()
}
}
// 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.keys[0].network }
func (a addr) String() string { return a.ln.addr }