summaryrefslogtreecommitdiffstats
path: root/dbus/dbus-transport.c
blob: 902919809116db330f23c0db2df17e180cd3c0a7 (plain)
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
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
/* dbus-transport.c DBusTransport object (internal to D-Bus implementation)
 *
 * Copyright (C) 2002, 2003  Red Hat Inc.
 *
 * Licensed under the Academic Free License version 2.1
 * 
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 */

#include "dbus-transport-protected.h"
#include "dbus-transport-unix.h"
#include "dbus-transport-socket.h"
#include "dbus-connection-internal.h"
#include "dbus-watch.h"
#include "dbus-auth.h"
#include "dbus-address.h"
#include "dbus-credentials.h"
#ifdef DBUS_BUILD_TESTS
#include "dbus-server-debug-pipe.h"
#endif

/**
 * @defgroup DBusTransport DBusTransport object
 * @ingroup  DBusInternals
 * @brief "Backend" for a DBusConnection.
 *
 * Types and functions related to DBusTransport.  A transport is an
 * abstraction that can send and receive data via various kinds of
 * network connections or other IPC mechanisms.
 * 
 * @{
 */

/**
 * @typedef DBusTransport
 *
 * Opaque object representing a way message stream.
 * DBusTransport abstracts various kinds of actual
 * transport mechanism, such as different network protocols,
 * or encryption schemes.
 */

static void
live_messages_size_notify (DBusCounter *counter,
                           void        *user_data)
{
  DBusTransport *transport = user_data;

  _dbus_transport_ref (transport);

#if 0
  _dbus_verbose ("Counter value is now %d\n",
                 (int) _dbus_counter_get_value (counter));
#endif
  
  /* disable or re-enable the read watch for the transport if
   * required.
   */
  if (transport->vtable->live_messages_changed)
    (* transport->vtable->live_messages_changed) (transport);

  _dbus_transport_unref (transport);
}

/**
 * Initializes the base class members of DBusTransport.  Chained up to
 * by subclasses in their constructor.  The server GUID is the
 * globally unique ID for the server creating this connection
 * and will be #NULL for the client side of a connection. The GUID
 * is in hex format.
 *
 * @param transport the transport being created.
 * @param vtable the subclass vtable.
 * @param server_guid non-#NULL if this transport is on the server side of a connection
 * @param address the address of the transport
 * @returns #TRUE on success.
 */
dbus_bool_t
_dbus_transport_init_base (DBusTransport             *transport,
                           const DBusTransportVTable *vtable,
                           const DBusString          *server_guid,
                           const DBusString          *address)
{
  DBusMessageLoader *loader;
  DBusAuth *auth;
  DBusCounter *counter;
  char *address_copy;
  DBusCredentials *creds;
  
  loader = _dbus_message_loader_new ();
  if (loader == NULL)
    return FALSE;
  
  if (server_guid)
    auth = _dbus_auth_server_new (server_guid);
  else
    auth = _dbus_auth_client_new ();
  if (auth == NULL)
    {
      _dbus_message_loader_unref (loader);
      return FALSE;
    }

  counter = _dbus_counter_new ();
  if (counter == NULL)
    {
      _dbus_auth_unref (auth);
      _dbus_message_loader_unref (loader);
      return FALSE;
    }  

  creds = _dbus_credentials_new ();
  if (creds == NULL)
    {
      _dbus_counter_unref (counter);
      _dbus_auth_unref (auth);
      _dbus_message_loader_unref (loader);
      return FALSE;
    }
  
  if (server_guid)
    {
      _dbus_assert (address == NULL);
      address_copy = NULL;
    }
  else
    {
      _dbus_assert (address != NULL);

      if (!_dbus_string_copy_data (address, &address_copy))
        {
          _dbus_credentials_unref (creds);
          _dbus_counter_unref (counter);
          _dbus_auth_unref (auth);
          _dbus_message_loader_unref (loader);
          return FALSE;
        }
    }
  
  transport->refcount = 1;
  transport->vtable = vtable;
  transport->loader = loader;
  transport->auth = auth;
  transport->live_messages_size = counter;
  transport->authenticated = FALSE;
  transport->disconnected = FALSE;
  transport->is_server = (server_guid != NULL);
  transport->send_credentials_pending = !transport->is_server;
  transport->receive_credentials_pending = transport->is_server;
  transport->address = address_copy;
  
  transport->unix_user_function = NULL;
  transport->unix_user_data = NULL;
  transport->free_unix_user_data = NULL;

  transport->windows_user_function = NULL;
  transport->windows_user_data = NULL;
  transport->free_windows_user_data = NULL;
  
  transport->expected_guid = NULL;
  
  /* Try to default to something that won't totally hose the system,
   * but doesn't impose too much of a limitation.
   */
  transport->max_live_messages_size = _DBUS_ONE_MEGABYTE * 63;

  /* credentials read from socket if any */
  transport->credentials = creds;
  
  _dbus_counter_set_notify (transport->live_messages_size,
                            transport->max_live_messages_size,
                            live_messages_size_notify,
                            transport);

  if (transport->address)
    _dbus_verbose ("Initialized transport on address %s\n", transport->address);
  
  return TRUE;
}

/**
 * Finalizes base class members of DBusTransport.
 * Chained up to from subclass finalizers.
 *
 * @param transport the transport.
 */
void
_dbus_transport_finalize_base (DBusTransport *transport)
{
  if (!transport->disconnected)
    _dbus_transport_disconnect (transport);

  if (transport->free_unix_user_data != NULL)
    (* transport->free_unix_user_data) (transport->unix_user_data);

  if (transport->free_windows_user_data != NULL)
    (* transport->free_windows_user_data) (transport->windows_user_data);
  
  _dbus_message_loader_unref (transport->loader);
  _dbus_auth_unref (transport->auth);
  _dbus_counter_set_notify (transport->live_messages_size,
                            0, NULL, NULL);
  _dbus_counter_unref (transport->live_messages_size);
  dbus_free (transport->address);
  dbus_free (transport->expected_guid);
  if (transport->credentials)
    _dbus_credentials_unref (transport->credentials);
}


/**
 * Verifies if a given D-Bus address is a valid address
 * by attempting to connect to it. If it is, returns the
 * opened DBusTransport object. If it isn't, returns #NULL
 * and sets @p error.
 *
 * @param error address where an error can be returned.
 * @returns a new transport, or #NULL on failure.
 */
static DBusTransport*
check_address (const char *address, DBusError *error)
{
  DBusAddressEntry **entries;
  DBusTransport *transport = NULL;
  int len, i;

  _dbus_assert (address != NULL);
  _dbus_assert (*address != '\0');

  if (!dbus_parse_address (address, &entries, &len, error))
    return FALSE;              /* not a valid address */

  for (i = 0; i < len; i++)
    {
      transport = _dbus_transport_open (entries[i], error);
      if (transport != NULL)
        break;
    }

  dbus_address_entries_free (entries);
  return transport;
}

/**
 * Creates a new transport for the "autostart" method.
 * This creates a client-side of a transport.
 *
 * @param error address where an error can be returned.
 * @returns a new transport, or #NULL on failure.
 */
static DBusTransport*
_dbus_transport_new_for_autolaunch (DBusError      *error)
{
  DBusString address;
  DBusTransport *result = NULL;

  _DBUS_ASSERT_ERROR_IS_CLEAR (error);

  if (!_dbus_string_init (&address))
    {
      dbus_set_error (error, DBUS_ERROR_NO_MEMORY, NULL);
      return NULL;
    }

  if (!_dbus_get_autolaunch_address (&address, error))
    {
      _DBUS_ASSERT_ERROR_IS_SET (error);
      goto out;
    }

  result = check_address (_dbus_string_get_const_data (&address), error);
  if (result == NULL)
    _DBUS_ASSERT_ERROR_IS_SET (error);
  else
    _DBUS_ASSERT_ERROR_IS_CLEAR (error);

 out:
  _dbus_string_free (&address);
  return result;
}

static DBusTransportOpenResult
_dbus_transport_open_autolaunch (DBusAddressEntry  *entry,
                                 DBusTransport    **transport_p,
                                 DBusError         *error)
{
  const char *method;
  
  method = dbus_address_entry_get_method (entry);
  _dbus_assert (method != NULL);

  if (strcmp (method, "autolaunch") == 0)
    {
      *transport_p = _dbus_transport_new_for_autolaunch (error);

      if (*transport_p == NULL)
        {
          _DBUS_ASSERT_ERROR_IS_SET (error);
          return DBUS_TRANSPORT_OPEN_DID_NOT_CONNECT;
        }
      else
        {
          _DBUS_ASSERT_ERROR_IS_CLEAR (error);
          return DBUS_TRANSPORT_OPEN_OK;
        }      
    }
  else
    {
      _DBUS_ASSERT_ERROR_IS_CLEAR (error);
      return DBUS_TRANSPORT_OPEN_NOT_HANDLED;
    }
}

static const struct {
  DBusTransportOpenResult (* func) (DBusAddressEntry *entry,
                                    DBusTransport   **transport_p,
                                    DBusError        *error);
} open_funcs[] = {
  { _dbus_transport_open_socket },
  { _dbus_transport_open_platform_specific },
  { _dbus_transport_open_autolaunch }
#ifdef DBUS_BUILD_TESTS
  , { _dbus_transport_open_debug_pipe }
#endif
};

/**
 * Try to open a new transport for the given address entry.  (This
 * opens a client-side-of-the-connection transport.)
 * 
 * @param entry the address entry
 * @param error location to store reason for failure.
 * @returns new transport of #NULL on failure.
 */
DBusTransport*
_dbus_transport_open (DBusAddressEntry *entry,
                      DBusError        *error)
{
  DBusTransport *transport;
  const char *expected_guid_orig;
  char *expected_guid;
  int i;
  DBusError tmp_error = DBUS_ERROR_INIT;

  _DBUS_ASSERT_ERROR_IS_CLEAR (error);
  
  transport = NULL;
  expected_guid_orig = dbus_address_entry_get_value (entry, "guid");
  expected_guid = _dbus_strdup (expected_guid_orig);

  if (expected_guid_orig != NULL && expected_guid == NULL)
    {
      _DBUS_SET_OOM (error);
      return NULL;
    }

  for (i = 0; i < (int) _DBUS_N_ELEMENTS (open_funcs); ++i)
    {
      DBusTransportOpenResult result;

      _DBUS_ASSERT_ERROR_IS_CLEAR (&tmp_error);
      result = (* open_funcs[i].func) (entry, &transport, &tmp_error);

      switch (result)
        {
        case DBUS_TRANSPORT_OPEN_OK:
          _DBUS_ASSERT_ERROR_IS_CLEAR (&tmp_error);
          goto out;
          break;
        case DBUS_TRANSPORT_OPEN_NOT_HANDLED:
          _DBUS_ASSERT_ERROR_IS_CLEAR (&tmp_error);
          /* keep going through the loop of open funcs */
          break;
        case DBUS_TRANSPORT_OPEN_BAD_ADDRESS:
          _DBUS_ASSERT_ERROR_IS_SET (&tmp_error);
          goto out;
          break;
        case DBUS_TRANSPORT_OPEN_DID_NOT_CONNECT:
          _DBUS_ASSERT_ERROR_IS_SET (&tmp_error);
          goto out;
          break;
        }
    }

 out:
  
  if (transport == NULL)
    {
      if (!dbus_error_is_set (&tmp_error))
        _dbus_set_bad_address (&tmp_error,
                               NULL, NULL,
                               "Unknown address type (examples of valid types are \"tcp\" and on UNIX \"unix\")");
      
      _DBUS_ASSERT_ERROR_IS_SET (&tmp_error);
      dbus_move_error(&tmp_error, error);
      dbus_free (expected_guid);
    }
  else
    {
      _DBUS_ASSERT_ERROR_IS_CLEAR (&tmp_error);

      /* In the case of autostart the initial guid is NULL
       * and the autostart transport recursively calls
       * _dbus_open_transport wich returns a transport
       * with a guid.  That guid is the definitive one.
       *
       * FIXME: if more transports are added they may have
       * an effect on the expected_guid semantics (i.e. 
       * expected_guid and transport->expected_guid may
       * both have values).  This is very unlikely though
       * we should either throw asserts here for those 
       * corner cases or refactor the code so it is 
       * clearer on what is expected and what is not
       */
      if(expected_guid)
        transport->expected_guid = expected_guid;
    }

  return transport;
}

/**
 * Increments the reference count for the transport.
 *
 * @param transport the transport.
 * @returns the transport.
 */
DBusTransport *
_dbus_transport_ref (DBusTransport *transport)
{
  _dbus_assert (transport->refcount > 0);
  
  transport->refcount += 1;

  return transport;
}

/**
 * Decrements the reference count for the transport.
 * Disconnects and finalizes the transport if
 * the reference count reaches zero.
 *
 * @param transport the transport.
 */
void
_dbus_transport_unref (DBusTransport *transport)
{
  _dbus_assert (transport != NULL);
  _dbus_assert (transport->refcount > 0);
  
  transport->refcount -= 1;
  if (transport->refcount == 0)
    {
      _dbus_verbose ("%s: finalizing\n", _DBUS_FUNCTION_NAME);
      
      _dbus_assert (transport->vtable->finalize != NULL);
      
      (* transport->vtable->finalize) (transport);
    }
}

/**
 * Closes our end of the connection to a remote application. Further
 * attempts to use this transport will fail. Only the first call to
 * _dbus_transport_disconnect() will have an effect.
 *
 * @param transport the transport.
 * 
 */
void
_dbus_transport_disconnect (DBusTransport *transport)
{
  _dbus_verbose ("%s start\n", _DBUS_FUNCTION_NAME);
  
  _dbus_assert (transport->vtable->disconnect != NULL);
  
  if (transport->disconnected)
    return;

  (* transport->vtable->disconnect) (transport);
  
  transport->disconnected = TRUE;

  _dbus_verbose ("%s end\n", _DBUS_FUNCTION_NAME);
}

/**
 * Returns #TRUE if the transport has not been disconnected.
 * Disconnection can result from _dbus_transport_disconnect()
 * or because the server drops its end of the connection.
 *
 * @param transport the transport.
 * @returns whether we're connected
 */
dbus_bool_t
_dbus_transport_get_is_connected (DBusTransport *transport)
{
  return !transport->disconnected;
}

static dbus_bool_t
auth_via_unix_user_function (DBusTransport *transport)
{
  DBusCredentials *auth_identity;
  dbus_bool_t allow;
  DBusConnection *connection;
  DBusAllowUnixUserFunction unix_user_function;
  void *unix_user_data;
  dbus_uid_t uid;

  /* Dropping the lock here probably isn't that safe. */
  
  auth_identity = _dbus_auth_get_identity (transport->auth);
  _dbus_assert (auth_identity != NULL);

  connection = transport->connection;
  unix_user_function = transport->unix_user_function;
  unix_user_data = transport->unix_user_data;
  uid = _dbus_credentials_get_unix_uid (auth_identity);
              
  _dbus_verbose ("unlock %s\n", _DBUS_FUNCTION_NAME);
  _dbus_connection_unlock (connection);

  allow = (* unix_user_function) (connection,
                                  uid,
                                  unix_user_data);
              
  _dbus_verbose ("lock %s post unix user function\n", _DBUS_FUNCTION_NAME);
  _dbus_connection_lock (connection);

  if (allow)
    {
      _dbus_verbose ("Client UID "DBUS_UID_FORMAT" authorized\n", uid);
    }
  else
    {
      _dbus_verbose ("Client UID "DBUS_UID_FORMAT
                     " was rejected, disconnecting\n",
                     _dbus_credentials_get_unix_uid (auth_identity));
      _dbus_transport_disconnect (transport);
    }

  return allow;
}

static dbus_bool_t
auth_via_windows_user_function (DBusTransport *transport)
{
  DBusCredentials *auth_identity;  
  dbus_bool_t allow;
  DBusConnection *connection;
  DBusAllowWindowsUserFunction windows_user_function;
  void *windows_user_data;
  char *windows_sid;

  /* Dropping the lock here probably isn't that safe. */
  
  auth_identity = _dbus_auth_get_identity (transport->auth);
  _dbus_assert (auth_identity != NULL);

  connection = transport->connection;
  windows_user_function = transport->windows_user_function;
  windows_user_data = transport->unix_user_data;
  windows_sid = _dbus_strdup (_dbus_credentials_get_windows_sid (auth_identity));

  if (windows_sid == NULL)
    {
      /* OOM */
      return FALSE;
    }
                
  _dbus_verbose ("unlock %s\n", _DBUS_FUNCTION_NAME);
  _dbus_connection_unlock (connection);

  allow = (* windows_user_function) (connection,
                                     windows_sid,
                                     windows_user_data);
              
  _dbus_verbose ("lock %s post windows user function\n", _DBUS_FUNCTION_NAME);
  _dbus_connection_lock (connection);

  if (allow)
    {
      _dbus_verbose ("Client SID '%s' authorized\n", windows_sid);
    }
  else
    {
      _dbus_verbose ("Client SID '%s' was rejected, disconnecting\n",
                     _dbus_credentials_get_windows_sid (auth_identity));
      _dbus_transport_disconnect (transport);
    }

  return allow;
}

static dbus_bool_t
auth_via_default_rules (DBusTransport *transport)
{
  DBusCredentials *auth_identity;
  DBusCredentials *our_identity;
  dbus_bool_t allow;
  
  auth_identity = _dbus_auth_get_identity (transport->auth);
  _dbus_assert (auth_identity != NULL);

  /* By default, connection is allowed if the client is 1) root or 2)
   * has the same UID as us or 3) anonymous is allowed.
   */
  
  our_identity = _dbus_credentials_new_from_current_process ();
  if (our_identity == NULL)
    {
      /* OOM */
      return FALSE;
    }
              
  if (transport->allow_anonymous ||
      _dbus_credentials_get_unix_uid (auth_identity) == 0 ||
      _dbus_credentials_same_user (our_identity,
                                   auth_identity))
    {
      if (_dbus_credentials_include(our_identity,DBUS_CREDENTIAL_WINDOWS_SID))
          _dbus_verbose ("Client authorized as SID '%s'"
                         "matching our SID '%s'\n",
                         _dbus_credentials_get_windows_sid(auth_identity),
                         _dbus_credentials_get_windows_sid(our_identity));
      else
          _dbus_verbose ("Client authorized as UID "DBUS_UID_FORMAT
                         " matching our UID "DBUS_UID_FORMAT"\n",
                         _dbus_credentials_get_unix_uid(auth_identity),
                         _dbus_credentials_get_unix_uid(our_identity));
      /* We have authenticated! */
      allow = TRUE;
    }
  else
    {
      if (_dbus_credentials_include(our_identity,DBUS_CREDENTIAL_WINDOWS_SID))
          _dbus_verbose ("Client authorized as SID '%s'"
                         " but our SID is '%s', disconnecting\n",
                         _dbus_credentials_get_windows_sid(our_identity),
                         _dbus_credentials_get_windows_sid(our_identity));
      else
          _dbus_verbose ("Client authorized as UID "DBUS_UID_FORMAT
                         " but our UID is "DBUS_UID_FORMAT", disconnecting\n",
                         _dbus_credentials_get_unix_uid(our_identity),
                         _dbus_credentials_get_unix_uid(our_identity));
      _dbus_transport_disconnect (transport);
      allow = FALSE;
    }  

  _dbus_credentials_unref (our_identity);
  
  return allow;
}


/**
 * Returns #TRUE if we have been authenticated.  Will return #TRUE
 * even if the transport is disconnected.
 *
 * @todo we drop connection->mutex when calling the unix_user_function,
 * and windows_user_function, which may not be safe really.
 *
 * @param transport the transport
 * @returns whether we're authenticated
 */
dbus_bool_t
_dbus_transport_get_is_authenticated (DBusTransport *transport)
{  
  if (transport->authenticated)
    return TRUE;
  else
    {
      dbus_bool_t maybe_authenticated;
      
      if (transport->disconnected)
        return FALSE;

      /* paranoia ref since we call user callbacks sometimes */
      _dbus_connection_ref_unlocked (transport->connection);
      
      maybe_authenticated =
        (!(transport->send_credentials_pending ||
           transport->receive_credentials_pending));

      if (maybe_authenticated)
        {
          switch (_dbus_auth_do_work (transport->auth))
            {
            case DBUS_AUTH_STATE_AUTHENTICATED:
              /* leave as maybe_authenticated */
              break;
            default:
              maybe_authenticated = FALSE;
            }
        }

      /* If we're the client, verify the GUID
       */
      if (maybe_authenticated && !transport->is_server)
        {
          const char *server_guid;

          server_guid = _dbus_auth_get_guid_from_server (transport->auth);
          _dbus_assert (server_guid != NULL);

          if (transport->expected_guid &&
              strcmp (transport->expected_guid, server_guid) != 0)
            {
              _dbus_verbose ("Client expected GUID '%s' and we got '%s' from the server\n",
                             transport->expected_guid, server_guid);
              _dbus_transport_disconnect (transport);
              _dbus_connection_unref_unlocked (transport->connection);
              return FALSE;
            }

          if (transport->expected_guid == NULL)
            {
              transport->expected_guid = _dbus_strdup (server_guid);

              if (transport->expected_guid == NULL)
                {
                  _dbus_verbose ("No memory to complete auth in %s\n", _DBUS_FUNCTION_NAME);
                  return FALSE;
                }
            }
        }

      /* If we're the server, see if we want to allow this identity to proceed.
       */
      if (maybe_authenticated && transport->is_server)
        {
          dbus_bool_t allow;
          DBusCredentials *auth_identity;
          
          auth_identity = _dbus_auth_get_identity (transport->auth);
          _dbus_assert (auth_identity != NULL);
          
          /* If we have an auth'd user and a user function, delegate
           * deciding whether auth credentials are good enough to the
           * app; otherwise, use our default decision process.
           */
          if (transport->unix_user_function != NULL &&
              _dbus_credentials_include (auth_identity, DBUS_CREDENTIAL_UNIX_USER_ID))
            {
              allow = auth_via_unix_user_function (transport);
            }
          else if (transport->windows_user_function != NULL &&
                   _dbus_credentials_include (auth_identity, DBUS_CREDENTIAL_WINDOWS_SID))
            {
              allow = auth_via_windows_user_function (transport);
            }      
          else
            {
              allow = auth_via_default_rules (transport);
            }
          
          if (!allow)
            maybe_authenticated = FALSE;
        }

      transport->authenticated = maybe_authenticated;

      _dbus_connection_unref_unlocked (transport->connection);
      return maybe_authenticated;
    }
}

/**
 * See dbus_connection_get_is_anonymous().
 *
 * @param transport the transport
 * @returns #TRUE if not authenticated or authenticated as anonymous
 */
dbus_bool_t
_dbus_transport_get_is_anonymous (DBusTransport *transport)
{
  DBusCredentials *auth_identity;
  
  if (!transport->authenticated)
    return TRUE;
  
  auth_identity = _dbus_auth_get_identity (transport->auth);

  if (_dbus_credentials_are_anonymous (auth_identity))
    return TRUE;
  else
    return FALSE;
}

/**
 * Gets the address of a transport. It will be
 * #NULL for a server-side transport.
 *
 * @param transport the transport
 * @returns transport's address
 */
const char*
_dbus_transport_get_address (DBusTransport *transport)
{
  return transport->address;
}

/**
 * Gets the id of the server we are connected to (see
 * dbus_server_get_id()). Only works on client side.
 *
 * @param transport the transport
 * @returns transport's server's id or #NULL if we are the server side
 */
const char*
_dbus_transport_get_server_id (DBusTransport *transport)
{
  if (transport->is_server)
    return NULL;
  else
    return transport->expected_guid;
}

/**
 * Handles a watch by reading data, writing data, or disconnecting
 * the transport, as appropriate for the given condition.
 *
 * @param transport the transport.
 * @param watch the watch.
 * @param condition the current state of the watched file descriptor.
 * @returns #FALSE if not enough memory to fully handle the watch
 */
dbus_bool_t
_dbus_transport_handle_watch (DBusTransport           *transport,
                              DBusWatch               *watch,
                              unsigned int             condition)
{
  dbus_bool_t retval;
  
  _dbus_assert (transport->vtable->handle_watch != NULL);

  if (transport->disconnected)
    return TRUE;

  if (dbus_watch_get_socket (watch) < 0)
    {
      _dbus_warn_check_failed ("Tried to handle an invalidated watch; this watch should have been removed\n");
      return TRUE;
    }
  
  _dbus_watch_sanitize_condition (watch, &condition);

  _dbus_transport_ref (transport);
  _dbus_watch_ref (watch);
  retval = (* transport->vtable->handle_watch) (transport, watch, condition);
  _dbus_watch_unref (watch);
  _dbus_transport_unref (transport);

  return retval;
}

/**
 * Sets the connection using this transport. Allows the transport
 * to add watches to the connection, queue incoming messages,
 * and pull outgoing messages.
 *
 * @param transport the transport.
 * @param connection the connection.
 * @returns #FALSE if not enough memory
 */
dbus_bool_t
_dbus_transport_set_connection (DBusTransport  *transport,
                                DBusConnection *connection)
{
  _dbus_assert (transport->vtable->connection_set != NULL);
  _dbus_assert (transport->connection == NULL);
  
  transport->connection = connection;

  _dbus_transport_ref (transport);
  if (!(* transport->vtable->connection_set) (transport))
    transport->connection = NULL;
  _dbus_transport_unref (transport);

  return transport->connection != NULL;
}

/**
 * Get the socket file descriptor, if any.
 *
 * @param transport the transport
 * @param fd_p pointer to fill in with the descriptor
 * @returns #TRUE if a descriptor was available
 */
dbus_bool_t
_dbus_transport_get_socket_fd (DBusTransport *transport,
                               int           *fd_p)
{
  dbus_bool_t retval;
  
  if (transport->vtable->get_socket_fd == NULL)
    return FALSE;

  if (transport->disconnected)
    return FALSE;

  _dbus_transport_ref (transport);

  retval = (* transport->vtable->get_socket_fd) (transport,
                                                 fd_p);
  
  _dbus_transport_unref (transport);

  return retval;
}

/**
 * Performs a single poll()/select() on the transport's file
 * descriptors and then reads/writes data as appropriate,
 * queueing incoming messages and sending outgoing messages.
 * This is the backend for _dbus_connection_do_iteration().
 * See _dbus_connection_do_iteration() for full details.
 *
 * @param transport the transport.
 * @param flags indicates whether to read or write, and whether to block.
 * @param timeout_milliseconds if blocking, timeout or -1 for no timeout.
 */
void
_dbus_transport_do_iteration (DBusTransport  *transport,
                              unsigned int    flags,
                              int             timeout_milliseconds)
{
  _dbus_assert (transport->vtable->do_iteration != NULL);

  _dbus_verbose ("Transport iteration flags 0x%x timeout %d connected = %d\n",
                 flags, timeout_milliseconds, !transport->disconnected);
  
  if ((flags & (DBUS_ITERATION_DO_WRITING |
                DBUS_ITERATION_DO_READING)) == 0)
    return; /* Nothing to do */

  if (transport->disconnected)
    return;

  _dbus_transport_ref (transport);
  (* transport->vtable->do_iteration) (transport, flags,
                                       timeout_milliseconds);
  _dbus_transport_unref (transport);

  _dbus_verbose ("%s end\n", _DBUS_FUNCTION_NAME);
}

static dbus_bool_t
recover_unused_bytes (DBusTransport *transport)
{
  if (_dbus_auth_needs_decoding (transport->auth))
    {
      DBusString plaintext;
      const DBusString *encoded;
      DBusString *buffer;
      int orig_len;
      
      if (!_dbus_string_init (&plaintext))
        goto nomem;
      
      _dbus_auth_get_unused_bytes (transport->auth,
                                   &encoded);

      if (!_dbus_auth_decode_data (transport->auth,
                                   encoded, &plaintext))
        {
          _dbus_string_free (&plaintext);
          goto nomem;
        }
      
      _dbus_message_loader_get_buffer (transport->loader,
                                       &buffer);
      
      orig_len = _dbus_string_get_length (buffer);
      
      if (!_dbus_string_move (&plaintext, 0, buffer,
                              orig_len))
        {
          _dbus_string_free (&plaintext);
          goto nomem;
        }
      
      _dbus_verbose (" %d unused bytes sent to message loader\n", 
                     _dbus_string_get_length (buffer) -
                     orig_len);
      
      _dbus_message_loader_return_buffer (transport->loader,
                                          buffer,
                                          _dbus_string_get_length (buffer) -
                                          orig_len);

      _dbus_auth_delete_unused_bytes (transport->auth);
      
      _dbus_string_free (&plaintext);
    }
  else
    {
      const DBusString *bytes;
      DBusString *buffer;
      int orig_len;
      dbus_bool_t succeeded;

      _dbus_message_loader_get_buffer (transport->loader,
                                       &buffer);
                
      orig_len = _dbus_string_get_length (buffer);
                
      _dbus_auth_get_unused_bytes (transport->auth,
                                   &bytes);

      succeeded = TRUE;
      if (!_dbus_string_copy (bytes, 0, buffer, _dbus_string_get_length (buffer)))
        succeeded = FALSE;
      
      _dbus_verbose (" %d unused bytes sent to message loader\n", 
                     _dbus_string_get_length (buffer) -
                     orig_len);
      
      _dbus_message_loader_return_buffer (transport->loader,
                                          buffer,
                                          _dbus_string_get_length (buffer) -
                                          orig_len);

      if (succeeded)
        _dbus_auth_delete_unused_bytes (transport->auth);
      else
        goto nomem;
    }

  return TRUE;

 nomem:
  _dbus_verbose ("Not enough memory to transfer unused bytes from auth conversation\n");
  return FALSE;
}

/**
 * Reports our current dispatch status (whether there's buffered
 * data to be queued as messages, or not, or we need memory).
 *
 * @param transport the transport
 * @returns current status
 */
DBusDispatchStatus
_dbus_transport_get_dispatch_status (DBusTransport *transport)
{
  if (_dbus_counter_get_value (transport->live_messages_size) >= transport->max_live_messages_size)
    return DBUS_DISPATCH_COMPLETE; /* complete for now */

  if (!_dbus_transport_get_is_authenticated (transport))
    {
      if (_dbus_auth_do_work (transport->auth) ==
          DBUS_AUTH_STATE_WAITING_FOR_MEMORY)
        return DBUS_DISPATCH_NEED_MEMORY;
      else if (!_dbus_transport_get_is_authenticated (transport))
        return DBUS_DISPATCH_COMPLETE;
    }

  if (!transport->unused_bytes_recovered &&
      !recover_unused_bytes (transport))
    return DBUS_DISPATCH_NEED_MEMORY;

  transport->unused_bytes_recovered = TRUE;
  
  if (!_dbus_message_loader_queue_messages (transport->loader))
    return DBUS_DISPATCH_NEED_MEMORY;

  if (_dbus_message_loader_peek_message (transport->loader) != NULL)
    return DBUS_DISPATCH_DATA_REMAINS;
  else
    return DBUS_DISPATCH_COMPLETE;
}

/**
 * Processes data we've read while handling a watch, potentially
 * converting some of it to messages and queueing those messages on
 * the connection.
 *
 * @param transport the transport
 * @returns #TRUE if we had enough memory to queue all messages
 */
dbus_bool_t
_dbus_transport_queue_messages (DBusTransport *transport)
{
  DBusDispatchStatus status;

#if 0
  _dbus_verbose ("_dbus_transport_queue_messages()\n");
#endif
  
  /* Queue any messages */
  while ((status = _dbus_transport_get_dispatch_status (transport)) == DBUS_DISPATCH_DATA_REMAINS)
    {
      DBusMessage *message;
      DBusList *link;

      link = _dbus_message_loader_pop_message_link (transport->loader);
      _dbus_assert (link != NULL);
      
      message = link->data;
      
      _dbus_verbose ("queueing received message %p\n", message);

      if (!_dbus_message_add_size_counter (message, transport->live_messages_size))
        {
          _dbus_message_loader_putback_message_link (transport->loader,
                                                     link);
          status = DBUS_DISPATCH_NEED_MEMORY;
          break;
        }
      else
        {
          /* pass ownership of link and message ref to connection */
          _dbus_connection_queue_received_message_link (transport->connection,
                                                        link);
        }
    }

  if (_dbus_message_loader_get_is_corrupted (transport->loader))
    {
      _dbus_verbose ("Corrupted message stream, disconnecting\n");
      _dbus_transport_disconnect (transport);
    }

  return status != DBUS_DISPATCH_NEED_MEMORY;
}

/**
 * See dbus_connection_set_max_message_size().
 *
 * @param transport the transport
 * @param size the max size of a single message
 */
void
_dbus_transport_set_max_message_size (DBusTransport  *transport,
                                      long            size)
{
  _dbus_message_loader_set_max_message_size (transport->loader, size);
}

/**
 * See dbus_connection_get_max_message_size().
 *
 * @param transport the transport
 * @returns max message size
 */
long
_dbus_transport_get_max_message_size (DBusTransport  *transport)
{
  return _dbus_message_loader_get_max_message_size (transport->loader);
}

/**
 * See dbus_connection_set_max_received_size().
 *
 * @param transport the transport
 * @param size the max size of all incoming messages
 */
void
_dbus_transport_set_max_received_size (DBusTransport  *transport,
                                       long            size)
{
  transport->max_live_messages_size = size;
  _dbus_counter_set_notify (transport->live_messages_size,
                            transport->max_live_messages_size,
                            live_messages_size_notify,
                            transport);
}


/**
 * See dbus_connection_get_max_received_size().
 *
 * @param transport the transport
 * @returns max bytes for all live messages
 */
long
_dbus_transport_get_max_received_size (DBusTransport  *transport)
{
  return transport->max_live_messages_size;
}

/**
 * See dbus_connection_get_unix_user().
 *
 * @param transport the transport
 * @param uid return location for the user ID
 * @returns #TRUE if uid is filled in with a valid user ID
 */
dbus_bool_t
_dbus_transport_get_unix_user (DBusTransport *transport,
                               unsigned long *uid)
{
  DBusCredentials *auth_identity;

  *uid = _DBUS_INT32_MAX; /* better than some root or system user in
                           * case of bugs in the caller. Caller should
                           * never use this value on purpose, however.
                           */
  
  if (!transport->authenticated)
    return FALSE;
  
  auth_identity = _dbus_auth_get_identity (transport->auth);

  if (_dbus_credentials_include (auth_identity,
                                 DBUS_CREDENTIAL_UNIX_USER_ID))
    {
      *uid = _dbus_credentials_get_unix_uid (auth_identity);
      return TRUE;
    }
  else
    return FALSE;
}

/**
 * See dbus_connection_get_unix_process_id().
 *
 * @param transport the transport
 * @param pid return location for the process ID
 * @returns #TRUE if uid is filled in with a valid process ID
 */
dbus_bool_t
_dbus_transport_get_unix_process_id (DBusTransport *transport,
				     unsigned long *pid)
{
  DBusCredentials *auth_identity;

  *pid = DBUS_PID_UNSET; /* Caller should never use this value on purpose,
			  * but we set it to a safe number, INT_MAX,
			  * just to root out possible bugs in bad callers.
			  */
  
  if (!transport->authenticated)
    return FALSE;
  
  auth_identity = _dbus_auth_get_identity (transport->auth);

  if (_dbus_credentials_include (auth_identity,
                                 DBUS_CREDENTIAL_UNIX_PROCESS_ID))
    {
      *pid = _dbus_credentials_get_unix_pid (auth_identity);
      return TRUE;
    }
  else
    return FALSE;
}

/**
 * See dbus_connection_get_adt_audit_session_data().
 *
 * @param transport the transport
 * @param data return location for the ADT audit data 
 * @param data_size return length of audit data
 * @returns #TRUE if audit data is filled in with a valid ucred
 */
dbus_bool_t
_dbus_transport_get_adt_audit_session_data (DBusTransport      *transport,
                                            void              **data,
                                            int                *data_size)
{
  DBusCredentials *auth_identity;

  *data = NULL;
  *data_size = 0;
  
  if (!transport->authenticated)
    return FALSE;
  
  auth_identity = _dbus_auth_get_identity (transport->auth);

  if (_dbus_credentials_include (auth_identity,
                                 DBUS_CREDENTIAL_ADT_AUDIT_DATA_ID))
    {
      *data = (void *) _dbus_credentials_get_adt_audit_data (auth_identity);
      *data_size = _dbus_credentials_get_adt_audit_data_size (auth_identity);
      return TRUE;
    }
  else
    return FALSE;
}

/**
 * See dbus_connection_set_unix_user_function().
 *
 * @param transport the transport
 * @param function the predicate
 * @param data data to pass to the predicate
 * @param free_data_function function to free the data
 * @param old_data the old user data to be freed
 * @param old_free_data_function old free data function to free it with
 */
void
_dbus_transport_set_unix_user_function (DBusTransport             *transport,
                                        DBusAllowUnixUserFunction  function,
                                        void                      *data,
                                        DBusFreeFunction           free_data_function,
                                        void                     **old_data,
                                        DBusFreeFunction          *old_free_data_function)
{  
  *old_data = transport->unix_user_data;
  *old_free_data_function = transport->free_unix_user_data;

  transport->unix_user_function = function;
  transport->unix_user_data = data;
  transport->free_unix_user_data = free_data_function;
}

/**
 * See dbus_connection_get_windows_user().
 *
 * @param transport the transport
 * @param windows_sid_p return location for the user ID
 * @returns #TRUE if user is available; the returned value may still be #NULL if no memory to copy it
 */
dbus_bool_t
_dbus_transport_get_windows_user (DBusTransport              *transport,
                                  char                      **windows_sid_p)
{
  DBusCredentials *auth_identity;

  *windows_sid_p = NULL;
  
  if (!transport->authenticated)
    return FALSE;
  
  auth_identity = _dbus_auth_get_identity (transport->auth);

  if (_dbus_credentials_include (auth_identity,
                                 DBUS_CREDENTIAL_WINDOWS_SID))
    {
      /* If no memory, we are supposed to return TRUE and set NULL */
      *windows_sid_p = _dbus_strdup (_dbus_credentials_get_windows_sid (auth_identity));

      return TRUE;
    }
  else
    return FALSE;
}

/**
 * See dbus_connection_set_windows_user_function().
 *
 * @param transport the transport
 * @param function the predicate
 * @param data data to pass to the predicate
 * @param free_data_function function to free the data
 * @param old_data the old user data to be freed
 * @param old_free_data_function old free data function to free it with
 */

void
_dbus_transport_set_windows_user_function (DBusTransport              *transport,
                                           DBusAllowWindowsUserFunction   function,
                                           void                       *data,
                                           DBusFreeFunction            free_data_function,
                                           void                      **old_data,
                                           DBusFreeFunction           *old_free_data_function)
{
  *old_data = transport->windows_user_data;
  *old_free_data_function = transport->free_windows_user_data;

  transport->windows_user_function = function;
  transport->windows_user_data = data;
  transport->free_windows_user_data = free_data_function;
}

/**
 * Sets the SASL authentication mechanisms supported by this transport.
 *
 * @param transport the transport
 * @param mechanisms the #NULL-terminated array of mechanisms
 *
 * @returns #FALSE if no memory
 */
dbus_bool_t
_dbus_transport_set_auth_mechanisms (DBusTransport  *transport,
                                     const char    **mechanisms)
{
  return _dbus_auth_set_mechanisms (transport->auth, mechanisms);
}

/**
 * See dbus_connection_set_allow_anonymous()
 *
 * @param transport the transport
 * @param value #TRUE to allow anonymous connection
 */
void
_dbus_transport_set_allow_anonymous (DBusTransport              *transport,
                                     dbus_bool_t                 value)
{
  transport->allow_anonymous = value != FALSE;
}

/** @} */