forked from tailscale/tailscale
-
Notifications
You must be signed in to change notification settings - Fork 0
/
server.go
1202 lines (1091 loc) · 33.1 KB
/
server.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
// Copyright (c) 2020 Tailscale Inc & AUTHORS All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package ipnserver
import (
"bufio"
"bytes"
"context"
"encoding/json"
"errors"
"fmt"
"io"
"log"
"net"
"net/http"
"net/netip"
"os"
"os/exec"
"os/signal"
"os/user"
"path/filepath"
"runtime"
"strconv"
"strings"
"sync"
"syscall"
"time"
"go4.org/mem"
"inet.af/peercred"
"tailscale.com/control/controlclient"
"tailscale.com/envknob"
"tailscale.com/ipn"
"tailscale.com/ipn/ipnlocal"
"tailscale.com/ipn/localapi"
"tailscale.com/logtail/backoff"
"tailscale.com/net/dnsfallback"
"tailscale.com/net/netstat"
"tailscale.com/net/netutil"
"tailscale.com/net/tsdial"
"tailscale.com/safesocket"
"tailscale.com/smallzstd"
"tailscale.com/tka"
"tailscale.com/types/logger"
"tailscale.com/util/groupmember"
"tailscale.com/util/pidowner"
"tailscale.com/util/systemd"
"tailscale.com/util/winutil"
"tailscale.com/version"
"tailscale.com/version/distro"
"tailscale.com/wgengine"
"tailscale.com/wgengine/monitor"
"tailscale.com/wgengine/netstack"
)
// Options is the configuration of the Tailscale node agent.
type Options 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
// AutostartStateKey, if non-empty, immediately starts the agent
// using the given StateKey. If empty, the agent stays idle and
// waits for a frontend to start it.
AutostartStateKey ipn.StateKey
// SurviveDisconnects specifies how the server reacts to its
// frontend disconnecting. If true, the server keeps running on
// its existing state, and accepts new frontend connections. If
// false, the server dumps its state and becomes idle.
//
// This is effectively whether the platform is in "server
// mode" by default. On Linux, it's true; on Windows, it's
// false. But on some platforms (currently only Windows), the
// "server mode" can be overridden at runtime with a change in
// Prefs.ForceDaemon/WantRunning.
//
// To support CLI connections (notably, "tailscale status"),
// the actual definition of "disconnect" is when the
// connection count transitions from 1 to 0.
SurviveDisconnects bool
// LoginFlags specifies the LoginFlags to pass to the client.
LoginFlags controlclient.LoginFlags
}
// Server is an IPN backend and its set of 0 or more active localhost
// TCP or unix socket connections talking to that backend.
type Server struct {
b *ipnlocal.LocalBackend
logf logger.Logf
backendLogID string
// resetOnZero is whether to call bs.Reset on transition from
// 1->0 connections. That is, this is whether the backend is
// being run in "client mode" that requires an active GUI
// connection (such as on Windows by default). Even if this
// is true, the ForceDaemon pref can override this.
resetOnZero bool
autostartStateKey ipn.StateKey
bsMu sync.Mutex // lock order: bsMu, then mu
bs *ipn.BackendServer
mu sync.Mutex
serverModeUser *user.User // or nil if not in server mode
lastUserID string // tracks last userid; on change, Reset state for paranoia
allClients map[net.Conn]connIdentity // HTTP or IPN
clients map[net.Conn]bool // subset of allClients; only IPN protocol
disconnectSub map[chan<- struct{}]struct{} // keys are subscribers of disconnects
}
// LocalBackend returns the server's LocalBackend.
func (s *Server) LocalBackend() *ipnlocal.LocalBackend { return s.b }
// connIdentity represents the owner of a localhost TCP or unix socket connection.
type connIdentity struct {
Conn net.Conn
NotWindows bool // runtime.GOOS != "windows"
// Fields used when NotWindows:
IsUnixSock bool // Conn is a *net.UnixConn
Creds *peercred.Creds // or nil
// Used on Windows:
// TODO(bradfitz): merge these into the peercreds package and
// use that for all.
Pid int
UserID string
User *user.User
}
// getConnIdentity returns the localhost TCP connection's identity information
// (pid, userid, user). If it's not Windows (for now), it returns a nil error
// and a ConnIdentity with NotWindows set true. It's only an error if we expected
// to be able to map it and couldn't.
func (s *Server) getConnIdentity(c net.Conn) (ci connIdentity, err error) {
ci = connIdentity{Conn: c}
if runtime.GOOS != "windows" { // for now; TODO: expand to other OSes
ci.NotWindows = true
_, ci.IsUnixSock = c.(*net.UnixConn)
ci.Creds, _ = peercred.Get(c)
return ci, nil
}
la, err := netip.ParseAddrPort(c.LocalAddr().String())
if err != nil {
return ci, fmt.Errorf("parsing local address: %w", err)
}
ra, err := netip.ParseAddrPort(c.RemoteAddr().String())
if err != nil {
return ci, fmt.Errorf("parsing local remote: %w", err)
}
if !la.Addr().IsLoopback() || !ra.Addr().IsLoopback() {
return ci, errors.New("non-loopback connection")
}
tab, err := netstat.Get()
if err != nil {
return ci, fmt.Errorf("failed to get local connection table: %w", err)
}
pid := peerPid(tab.Entries, la, ra)
if pid == 0 {
return ci, errors.New("no local process found matching localhost connection")
}
ci.Pid = pid
uid, err := pidowner.OwnerOfPID(pid)
if err != nil {
var hint string
if runtime.GOOS == "windows" {
hint = " (WSL?)"
}
return ci, fmt.Errorf("failed to map connection's pid to a user%s: %w", hint, err)
}
ci.UserID = uid
u, err := lookupUserFromID(s.logf, uid)
if err != nil {
return ci, fmt.Errorf("failed to look up user from userid: %w", err)
}
ci.User = u
return ci, nil
}
func lookupUserFromID(logf logger.Logf, uid string) (*user.User, error) {
u, err := user.LookupId(uid)
if err != nil && runtime.GOOS == "windows" && errors.Is(err, syscall.Errno(0x534)) {
// The below workaround is only applicable when uid represents a
// valid security principal. Omitting this check causes us to succeed
// even when uid represents a deleted user.
if !winutil.IsSIDValidPrincipal(uid) {
return nil, err
}
logf("[warning] issue 869: os/user.LookupId failed; ignoring")
// Work around https://github.com/tailscale/tailscale/issues/869 for
// now. We don't strictly need the username. It's just a nice-to-have.
// So make up a *user.User if their machine is broken in this way.
return &user.User{
Uid: uid,
Username: "unknown-user-" + uid,
Name: "unknown user " + uid,
}, nil
}
return u, err
}
// blockWhileInUse blocks while until either a Read from conn fails
// (i.e. it's closed) or until the server is able to accept ci as a
// user.
func (s *Server) blockWhileInUse(conn io.Reader, ci connIdentity) {
s.logf("blocking client while server in use; connIdentity=%v", ci)
connDone := make(chan struct{})
go func() {
io.Copy(io.Discard, conn)
close(connDone)
}()
ch := make(chan struct{}, 1)
s.registerDisconnectSub(ch, true)
defer s.registerDisconnectSub(ch, false)
for {
select {
case <-connDone:
s.logf("blocked client Read completed; connIdentity=%v", ci)
return
case <-ch:
s.mu.Lock()
err := s.checkConnIdentityLocked(ci)
s.mu.Unlock()
if err == nil {
s.logf("unblocking client, server is free; connIdentity=%v", ci)
// Server is now available again for a new user.
// TODO(bradfitz): keep this connection alive. But for
// now just return and have our caller close the connection
// (which unblocks the io.Copy goroutine we started above)
// and then the client (e.g. Windows) will reconnect and
// discover that it works.
return
}
}
}
}
// bufferHasHTTPRequest reports whether br looks like it has an HTTP
// request in it, without reading any bytes from it.
func bufferHasHTTPRequest(br *bufio.Reader) bool {
peek, _ := br.Peek(br.Buffered())
return mem.HasPrefix(mem.B(peek), mem.S("GET ")) ||
mem.HasPrefix(mem.B(peek), mem.S("POST ")) ||
mem.Contains(mem.B(peek), mem.S(" HTTP/"))
}
// bufferIsConnect reports whether br looks like it's likely an HTTP
// CONNECT request.
//
// Invariant: br has already had at least 4 bytes Peek'ed.
func bufferIsConnect(br *bufio.Reader) bool {
peek, _ := br.Peek(br.Buffered())
return mem.HasPrefix(mem.B(peek), mem.S("CONN"))
}
func (s *Server) serveConn(ctx context.Context, c net.Conn, logf logger.Logf) {
// First see if it's an HTTP request.
br := bufio.NewReader(c)
c.SetReadDeadline(time.Now().Add(time.Second))
br.Peek(4)
c.SetReadDeadline(time.Time{})
// Handle logtail CONNECT requests early. (See docs on handleProxyConnectConn)
if bufferIsConnect(br) {
s.handleProxyConnectConn(ctx, br, c, logf)
return
}
isHTTPReq := bufferHasHTTPRequest(br)
ci, err := s.addConn(c, isHTTPReq)
if err != nil {
if isHTTPReq {
fmt.Fprintf(c, "HTTP/1.0 500 Nope\r\nContent-Type: text/plain\r\nX-Content-Type-Options: nosniff\r\n\r\n%s\n", err.Error())
c.Close()
return
}
defer c.Close()
bs := ipn.NewBackendServer(logf, nil, jsonNotifier(c, s.logf))
_, occupied := err.(inUseOtherUserError)
if occupied {
bs.SendInUseOtherUserErrorMessage(err.Error())
s.blockWhileInUse(c, ci)
} else {
bs.SendErrorMessage(err.Error())
time.Sleep(time.Second)
}
return
}
// Tell the LocalBackend about the identity we're now running as.
s.b.SetCurrentUserID(ci.UserID)
if isHTTPReq {
httpServer := &http.Server{
// Localhost connections are cheap; so only do
// keep-alives for a short period of time, as these
// active connections lock the server into only serving
// that user. If the user has this page open, we don't
// want another switching user to be locked out for
// minutes. 5 seconds is enough to let browser hit
// favicon.ico and such.
IdleTimeout: 5 * time.Second,
ErrorLog: logger.StdLogger(logf),
Handler: s.localhostHandler(ci),
}
httpServer.Serve(netutil.NewOneConnListener(&protoSwitchConn{s: s, br: br, Conn: c}, nil))
return
}
defer s.removeAndCloseConn(c)
logf("[v1] incoming control connection")
if isReadonlyConn(ci, s.b.OperatorUserID(), logf) {
ctx = ipn.ReadonlyContextOf(ctx)
}
for ctx.Err() == nil {
msg, err := ipn.ReadMsg(br)
if err != nil {
if errors.Is(err, io.EOF) {
logf("[v1] ReadMsg: %v", err)
} else if ctx.Err() == nil {
logf("ReadMsg: %v", err)
}
return
}
s.bsMu.Lock()
if err := s.bs.GotCommandMsg(ctx, msg); err != nil {
logf("GotCommandMsg: %v", err)
}
gotQuit := s.bs.GotQuit
s.bsMu.Unlock()
if gotQuit {
return
}
}
}
func isReadonlyConn(ci connIdentity, operatorUID string, logf logger.Logf) bool {
if runtime.GOOS == "windows" {
// Windows doesn't need/use this mechanism, at least yet. It
// has a different last-user-wins auth model.
return false
}
const ro = true
const rw = false
if !safesocket.PlatformUsesPeerCreds() {
return rw
}
creds := ci.Creds
if creds == nil {
logf("connection from unknown peer; read-only")
return ro
}
uid, ok := creds.UserID()
if !ok {
logf("connection from peer with unknown userid; read-only")
return ro
}
if uid == "0" {
logf("connection from userid %v; root has access", uid)
return rw
}
if selfUID := os.Getuid(); selfUID != 0 && uid == strconv.Itoa(selfUID) {
logf("connection from userid %v; connection from non-root user matching daemon has access", uid)
return rw
}
if operatorUID != "" && uid == operatorUID {
logf("connection from userid %v; is configured operator", uid)
return rw
}
if yes, err := isLocalAdmin(uid); err != nil {
logf("connection from userid %v; read-only; %v", uid, err)
return ro
} else if yes {
logf("connection from userid %v; is local admin, has access", uid)
return rw
}
logf("connection from userid %v; read-only", uid)
return ro
}
func isLocalAdmin(uid string) (bool, error) {
u, err := user.LookupId(uid)
if err != nil {
return false, err
}
var adminGroup string
switch {
case runtime.GOOS == "darwin":
adminGroup = "admin"
case distro.Get() == distro.QNAP:
adminGroup = "administrators"
default:
return false, fmt.Errorf("no system admin group found")
}
return groupmember.IsMemberOfGroup(adminGroup, u.Username)
}
// inUseOtherUserError is the error type for when the server is in use
// by a different local user.
type inUseOtherUserError struct{ error }
func (e inUseOtherUserError) Unwrap() error { return e.error }
// checkConnIdentityLocked checks whether the provided identity is
// allowed to connect to the server.
//
// The returned error, when non-nil, will be of type inUseOtherUserError.
//
// s.mu must be held.
func (s *Server) checkConnIdentityLocked(ci connIdentity) error {
// If clients are already connected, verify they're the same user.
// This mostly matters on Windows at the moment.
if len(s.allClients) > 0 {
var active connIdentity
for _, active = range s.allClients {
break
}
if ci.UserID != active.UserID {
return inUseOtherUserError{fmt.Errorf("Tailscale already in use by %s, pid %d", active.User.Username, active.Pid)}
}
}
if su := s.serverModeUser; su != nil && ci.UserID != su.Uid {
return inUseOtherUserError{fmt.Errorf("Tailscale already in use by %s", su.Username)}
}
return nil
}
// localAPIPermissions returns the permissions for the given identity accessing
// the Tailscale local daemon API.
//
// s.mu must not be held.
func (s *Server) localAPIPermissions(ci connIdentity) (read, write bool) {
switch runtime.GOOS {
case "windows":
s.mu.Lock()
defer s.mu.Unlock()
if s.checkConnIdentityLocked(ci) == nil {
return true, true
}
return false, false
case "js":
return true, true
}
if ci.IsUnixSock {
return true, !isReadonlyConn(ci, s.b.OperatorUserID(), logger.Discard)
}
return false, false
}
// userIDFromString maps from either a numeric user id in string form
// ("998") or username ("caddy") to its string userid ("998").
// It returns the empty string on error.
func userIDFromString(v string) string {
if v == "" || isAllDigit(v) {
return v
}
u, err := user.Lookup(v)
if err != nil {
return ""
}
return u.Uid
}
func isAllDigit(s string) bool {
for i := 0; i < len(s); i++ {
if b := s[i]; b < '0' || b > '9' {
return false
}
}
return true
}
// connCanFetchCerts reports whether ci is allowed to fetch HTTPS
// certs from this server when it wouldn't otherwise be able to.
//
// That is, this reports whether ci should grant additional
// capabilities over what the conn would otherwise be able to do.
//
// For now this only returns true on Unix machines when
// TS_PERMIT_CERT_UID is set the to the userid of the peer
// connection. It's intended to give your non-root webserver access
// (www-data, caddy, nginx, etc) to certs.
func (s *Server) connCanFetchCerts(ci connIdentity) bool {
if ci.IsUnixSock && ci.Creds != nil {
connUID, ok := ci.Creds.UserID()
if ok && connUID == userIDFromString(envknob.String("TS_PERMIT_CERT_UID")) {
return true
}
}
return false
}
// registerDisconnectSub adds ch as a subscribe to connection disconnect
// events. If add is false, the subscriber is removed.
func (s *Server) registerDisconnectSub(ch chan<- struct{}, add bool) {
s.mu.Lock()
defer s.mu.Unlock()
if add {
if s.disconnectSub == nil {
s.disconnectSub = make(map[chan<- struct{}]struct{})
}
s.disconnectSub[ch] = struct{}{}
} else {
delete(s.disconnectSub, ch)
}
}
// addConn adds c to the server's list of clients.
//
// If the returned error is of type inUseOtherUserError then the
// returned connIdentity is also valid.
func (s *Server) addConn(c net.Conn, isHTTP bool) (ci connIdentity, err error) {
ci, err = s.getConnIdentity(c)
if err != nil {
return
}
// If the connected user changes, reset the backend server state to make
// sure node keys don't leak between users.
var doReset bool
defer func() {
if doReset {
s.logf("identity changed; resetting server")
s.b.ResetForClientDisconnect()
}
}()
s.mu.Lock()
defer s.mu.Unlock()
if s.clients == nil {
s.clients = map[net.Conn]bool{}
}
if s.allClients == nil {
s.allClients = map[net.Conn]connIdentity{}
}
if err := s.checkConnIdentityLocked(ci); err != nil {
return ci, err
}
if !isHTTP {
s.clients[c] = true
}
s.allClients[c] = ci
if s.lastUserID != ci.UserID {
if s.lastUserID != "" {
doReset = true
}
s.lastUserID = ci.UserID
}
return ci, nil
}
func (s *Server) removeAndCloseConn(c net.Conn) {
s.mu.Lock()
delete(s.clients, c)
delete(s.allClients, c)
remain := len(s.allClients)
for sub := range s.disconnectSub {
select {
case sub <- struct{}{}:
default:
}
}
s.mu.Unlock()
if remain == 0 && s.resetOnZero {
if s.b.InServerMode() {
s.logf("client disconnected; staying alive in server mode")
} else {
s.logf("client disconnected; stopping server")
s.b.ResetForClientDisconnect()
}
}
c.Close()
}
func (s *Server) stopAll() {
s.mu.Lock()
defer s.mu.Unlock()
for c := range s.clients {
safesocket.ConnCloseRead(c)
safesocket.ConnCloseWrite(c)
}
s.clients = nil
}
// setServerModeUserLocked is called when we're in server mode but our s.serverModeUser is nil.
//
// s.mu must be held
func (s *Server) setServerModeUserLocked() {
var ci connIdentity
var ok bool
for _, ci = range s.allClients {
ok = true
break
}
if !ok {
s.logf("ipnserver: [unexpected] now in server mode, but no connected client")
return
}
if ci.NotWindows {
return
}
if ci.User != nil {
s.logf("ipnserver: now in server mode; user=%v", ci.User.Username)
s.serverModeUser = ci.User
} else {
s.logf("ipnserver: [unexpected] now in server mode, but nil User")
}
}
var jsonEscapedZero = []byte(`\u0000`)
func (s *Server) writeToClients(n ipn.Notify) {
inServerMode := s.b.InServerMode()
s.mu.Lock()
defer s.mu.Unlock()
if inServerMode {
if s.serverModeUser == nil {
s.setServerModeUserLocked()
}
} else {
if s.serverModeUser != nil {
s.logf("ipnserver: no longer in server mode")
s.serverModeUser = nil
}
}
if len(s.clients) == 0 {
// Common case (at least on busy servers): nobody
// connected (no GUI, etc), so return before
// serializing JSON.
return
}
if b, ok := marshalNotify(n, s.logf); ok {
for c := range s.clients {
ipn.WriteMsg(c, b)
}
}
}
// Run runs a Tailscale backend service.
// The getEngine func is called repeatedly, once per connection, until it returns an engine successfully.
//
// Deprecated: use New and Server.Run instead.
func Run(ctx context.Context, logf logger.Logf, ln net.Listener, store ipn.StateStore, linkMon *monitor.Mon, dialer *tsdial.Dialer, logid string, getEngine func() (wgengine.Engine, *netstack.Impl, error), opts Options) error {
getEngine = getEngineUntilItWorksWrapper(getEngine)
runDone := make(chan struct{})
defer close(runDone)
var serverMu sync.Mutex
var serverOrNil *Server
// When the context is closed or when we return, whichever is first, close our listener
// and all open connections.
go func() {
select {
case <-ctx.Done():
case <-runDone:
}
serverMu.Lock()
if s := serverOrNil; s != nil {
s.stopAll()
}
serverMu.Unlock()
ln.Close()
}()
logf("Listening on %v", ln.Addr())
var serverModeUser *user.User
if opts.AutostartStateKey == "" {
autoStartKey, err := store.ReadState(ipn.ServerModeStartKey)
if err != nil && err != ipn.ErrStateNotExist {
return fmt.Errorf("calling ReadState on state store: %w", err)
}
key := string(autoStartKey)
if strings.HasPrefix(key, "user-") {
uid := strings.TrimPrefix(key, "user-")
u, err := lookupUserFromID(logf, uid)
if err != nil {
logf("ipnserver: found server mode auto-start key %q; failed to load user: %v", key, err)
} else {
logf("ipnserver: found server mode auto-start key %q (user %s)", key, u.Username)
serverModeUser = u
}
opts.AutostartStateKey = ipn.StateKey(key)
}
}
bo := backoff.NewBackoff("ipnserver", logf, 30*time.Second)
var unservedConn net.Conn // if non-nil, accepted, but hasn't served yet
eng, ns, err := getEngine()
if err != nil {
logf("ipnserver: initial getEngine call: %v", err)
for i := 1; ctx.Err() == nil; i++ {
c, err := ln.Accept()
if err != nil {
logf("%d: Accept: %v", i, err)
bo.BackOff(ctx, err)
continue
}
logf("ipnserver: try%d: trying getEngine again...", i)
eng, ns, err = getEngine()
if err == nil {
logf("%d: GetEngine worked; exiting failure loop", i)
unservedConn = c
break
}
logf("ipnserver%d: getEngine failed again: %v", i, err)
errMsg := err.Error()
go func() {
defer c.Close()
bs := ipn.NewBackendServer(logf, nil, jsonNotifier(c, logf))
bs.SendErrorMessage(errMsg)
time.Sleep(time.Second)
}()
}
if err := ctx.Err(); err != nil {
return err
}
}
if unservedConn != nil {
ln = &listenerWithReadyConn{
Listener: ln,
c: unservedConn,
}
}
server, err := New(logf, logid, store, eng, dialer, serverModeUser, opts)
if err != nil {
return err
}
if ns != nil {
ns.SetLocalBackend(server.LocalBackend())
}
serverMu.Lock()
serverOrNil = server
serverMu.Unlock()
return server.Run(ctx, ln)
}
// New returns a new Server.
//
// To start it, use the Server.Run method.
func New(logf logger.Logf, logid string, store ipn.StateStore, eng wgengine.Engine, dialer *tsdial.Dialer, serverModeUser *user.User, opts Options) (*Server, error) {
b, err := ipnlocal.NewLocalBackend(logf, logid, store, dialer, eng, opts.LoginFlags)
if err != nil {
return nil, fmt.Errorf("NewLocalBackend: %v", err)
}
b.SetVarRoot(opts.VarRoot)
b.SetDecompressor(func() (controlclient.Decompressor, error) {
return smallzstd.NewDecoder(nil)
})
if root := b.TailscaleVarRoot(); root != "" {
chonkDir := filepath.Join(root, "tka")
if _, err := os.Stat(chonkDir); err == nil {
// The directory exists, which means network-lock has been initialized.
storage, err := tka.ChonkDir(chonkDir)
if err != nil {
return nil, fmt.Errorf("opening tailchonk: %v", err)
}
authority, err := tka.Open(storage)
if err != nil {
return nil, fmt.Errorf("initializing tka: %v", err)
}
b.SetTailnetKeyAuthority(authority, storage)
logf("tka initialized at head %x", authority.Head())
}
dnsfallback.SetCachePath(filepath.Join(root, "derpmap.cached.json"))
} else {
logf("network-lock unavailable; no state directory")
}
dg := distro.Get()
switch dg {
case distro.Synology, distro.TrueNAS, distro.QNAP:
// See if they have a "Taildrop" share.
// See https://github.com/tailscale/tailscale/issues/2179#issuecomment-982821319
path, err := findTaildropDir(dg)
if err != nil {
logf("%s Taildrop support: %v", dg, err)
} else {
logf("%s Taildrop: using %v", dg, path)
b.SetDirectFileRoot(path)
b.SetDirectFileDoFinalRename(true)
}
}
if opts.AutostartStateKey == "" {
autoStartKey, err := store.ReadState(ipn.ServerModeStartKey)
if err != nil && err != ipn.ErrStateNotExist {
return nil, fmt.Errorf("calling ReadState on store: %w", err)
}
key := string(autoStartKey)
if strings.HasPrefix(key, "user-") {
uid := strings.TrimPrefix(key, "user-")
u, err := lookupUserFromID(logf, uid)
if err != nil {
logf("ipnserver: found server mode auto-start key %q; failed to load user: %v", key, err)
} else {
logf("ipnserver: found server mode auto-start key %q (user %s)", key, u.Username)
serverModeUser = u
}
opts.AutostartStateKey = ipn.StateKey(key)
}
}
server := &Server{
b: b,
backendLogID: logid,
logf: logf,
resetOnZero: !opts.SurviveDisconnects,
serverModeUser: serverModeUser,
autostartStateKey: opts.AutostartStateKey,
}
server.bs = ipn.NewBackendServer(logf, b, server.writeToClients)
return server, nil
}
// Run runs the server, accepting connections from ln forever.
//
// If the context is done, the listener is closed.
func (s *Server) Run(ctx context.Context, ln net.Listener) error {
defer s.b.Shutdown()
runDone := make(chan struct{})
defer close(runDone)
// When the context is closed or when we return, whichever is first, close our listener
// and all open connections.
go func() {
select {
case <-ctx.Done():
case <-runDone:
}
s.stopAll()
ln.Close()
}()
if s.autostartStateKey != "" {
s.bs.GotCommand(ctx, &ipn.Command{
Version: version.Long,
Start: &ipn.StartArgs{
Opts: ipn.Options{StateKey: s.autostartStateKey},
},
})
}
systemd.Ready()
bo := backoff.NewBackoff("ipnserver", s.logf, 30*time.Second)
var connNum int
for {
if ctx.Err() != nil {
return ctx.Err()
}
c, err := ln.Accept()
if err != nil {
if ctx.Err() != nil {
return ctx.Err()
}
s.logf("ipnserver: Accept: %v", err)
bo.BackOff(ctx, err)
continue
}
connNum++
go s.serveConn(ctx, c, logger.WithPrefix(s.logf, fmt.Sprintf("ipnserver: conn%d: ", connNum)))
}
}
// BabysitProc runs the current executable as a child process with the
// provided args, capturing its output, writing it to files, and
// restarting the process on any crashes.
//
// It's only currently (2020-10-29) used on Windows.
func BabysitProc(ctx context.Context, args []string, logf logger.Logf) {
executable, err := os.Executable()
if err != nil {
panic("cannot determine executable: " + err.Error())
}
var proc struct {
mu sync.Mutex
p *os.Process
}
done := make(chan struct{})
go func() {
interrupt := make(chan os.Signal, 1)
signal.Notify(interrupt, syscall.SIGINT, syscall.SIGTERM)
var sig os.Signal
select {
case sig = <-interrupt:
logf("BabysitProc: got signal: %v", sig)
close(done)
case <-ctx.Done():
logf("BabysitProc: context done")
sig = os.Kill
close(done)
}
proc.mu.Lock()
proc.p.Signal(sig)
proc.mu.Unlock()
}()
bo := backoff.NewBackoff("BabysitProc", logf, 30*time.Second)
for {
startTime := time.Now()
log.Printf("exec: %#v %v", executable, args)
cmd := exec.Command(executable, args...)
// Create a pipe object to use as the subproc's stdin.
// When the writer goes away, the reader gets EOF.
// A subproc can watch its stdin and exit when it gets EOF;
// this is a very reliable way to have a subproc die when
// its parent (us) disappears.
// We never need to actually write to wStdin.
rStdin, wStdin, err := os.Pipe()
if err != nil {
log.Printf("os.Pipe 1: %v", err)
return
}
// Create a pipe object to use as the subproc's stdout/stderr.
// We'll read from this pipe and send it to logf, line by line.
// We can't use os.exec's io.Writer for this because it
// doesn't care about lines, and thus ends up merging multiple
// log lines into one or splitting one line into multiple
// logf() calls. bufio is more appropriate.
rStdout, wStdout, err := os.Pipe()
if err != nil {
log.Printf("os.Pipe 2: %v", err)
}
go func(r *os.File) {
defer r.Close()
rb := bufio.NewReader(r)
for {
s, err := rb.ReadString('\n')
if s != "" {
logf("%s", s)
}
if err != nil {
break
}
}
}(rStdout)
cmd.Stdin = rStdin
cmd.Stdout = wStdout
cmd.Stderr = wStdout
err = cmd.Start()
// Now that the subproc is started, get rid of our copy of the
// pipe reader. Bad things happen on Windows if more than one
// process owns the read side of a pipe.
rStdin.Close()
wStdout.Close()
if err != nil {
log.Printf("starting subprocess failed: %v", err)
} else {
proc.mu.Lock()
proc.p = cmd.Process
proc.mu.Unlock()
err = cmd.Wait()
log.Printf("subprocess exited: %v", err)
}
// If the process finishes, clean up the write side of the
// pipe. We'll make a new one when we restart the subproc.
wStdin.Close()
if os.Getenv("TS_DEBUG_RESTART_CRASHED") == "0" {
log.Fatalf("Process ended.")
}