This file is indexed.

/usr/lib/python2.7/imaplib.py is in libpython2.7-stdlib 2.7.11-7ubuntu1.

This file is owned by root:root, with mode 0o644.

The actual contents of the file can be viewed below.

   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
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
"""IMAP4 client.

Based on RFC 2060.

Public class:           IMAP4
Public variable:        Debug
Public functions:       Internaldate2tuple
                        Int2AP
                        ParseFlags
                        Time2Internaldate
"""

# Author: Piers Lauder <piers@cs.su.oz.au> December 1997.
#
# Authentication code contributed by Donn Cave <donn@u.washington.edu> June 1998.
# String method conversion by ESR, February 2001.
# GET/SETACL contributed by Anthony Baxter <anthony@interlink.com.au> April 2001.
# IMAP4_SSL contributed by Tino Lange <Tino.Lange@isg.de> March 2002.
# GET/SETQUOTA contributed by Andreas Zeidler <az@kreativkombinat.de> June 2002.
# PROXYAUTH contributed by Rick Holbert <holbert.13@osu.edu> November 2002.
# GET/SETANNOTATION contributed by Tomas Lindroos <skitta@abo.fi> June 2005.

__version__ = "2.58"

import binascii, errno, random, re, socket, subprocess, sys, time

__all__ = ["IMAP4", "IMAP4_stream", "Internaldate2tuple",
           "Int2AP", "ParseFlags", "Time2Internaldate"]

#       Globals

CRLF = '\r\n'
Debug = 0
IMAP4_PORT = 143
IMAP4_SSL_PORT = 993
AllowedVersions = ('IMAP4REV1', 'IMAP4')        # Most recent first

# Maximal line length when calling readline(). This is to prevent
# reading arbitrary length lines. RFC 3501 and 2060 (IMAP 4rev1)
# don't specify a line length. RFC 2683 suggests limiting client
# command lines to 1000 octets and that servers should be prepared
# to accept command lines up to 8000 octets, so we used to use 10K here.
# In the modern world (eg: gmail) the response to, for example, a
# search command can be quite large, so we now use 1M.
_MAXLINE = 1000000


#       Commands

Commands = {
        # name            valid states
        'APPEND':       ('AUTH', 'SELECTED'),
        'AUTHENTICATE': ('NONAUTH',),
        'CAPABILITY':   ('NONAUTH', 'AUTH', 'SELECTED', 'LOGOUT'),
        'CHECK':        ('SELECTED',),
        'CLOSE':        ('SELECTED',),
        'COPY':         ('SELECTED',),
        'CREATE':       ('AUTH', 'SELECTED'),
        'DELETE':       ('AUTH', 'SELECTED'),
        'DELETEACL':    ('AUTH', 'SELECTED'),
        'EXAMINE':      ('AUTH', 'SELECTED'),
        'EXPUNGE':      ('SELECTED',),
        'FETCH':        ('SELECTED',),
        'GETACL':       ('AUTH', 'SELECTED'),
        'GETANNOTATION':('AUTH', 'SELECTED'),
        'GETQUOTA':     ('AUTH', 'SELECTED'),
        'GETQUOTAROOT': ('AUTH', 'SELECTED'),
        'MYRIGHTS':     ('AUTH', 'SELECTED'),
        'LIST':         ('AUTH', 'SELECTED'),
        'LOGIN':        ('NONAUTH',),
        'LOGOUT':       ('NONAUTH', 'AUTH', 'SELECTED', 'LOGOUT'),
        'LSUB':         ('AUTH', 'SELECTED'),
        'NAMESPACE':    ('AUTH', 'SELECTED'),
        'NOOP':         ('NONAUTH', 'AUTH', 'SELECTED', 'LOGOUT'),
        'PARTIAL':      ('SELECTED',),                                  # NB: obsolete
        'PROXYAUTH':    ('AUTH',),
        'RENAME':       ('AUTH', 'SELECTED'),
        'SEARCH':       ('SELECTED',),
        'SELECT':       ('AUTH', 'SELECTED'),
        'SETACL':       ('AUTH', 'SELECTED'),
        'SETANNOTATION':('AUTH', 'SELECTED'),
        'SETQUOTA':     ('AUTH', 'SELECTED'),
        'SORT':         ('SELECTED',),
        'STATUS':       ('AUTH', 'SELECTED'),
        'STORE':        ('SELECTED',),
        'SUBSCRIBE':    ('AUTH', 'SELECTED'),
        'THREAD':       ('SELECTED',),
        'UID':          ('SELECTED',),
        'UNSUBSCRIBE':  ('AUTH', 'SELECTED'),
        }

#       Patterns to match server responses

Continuation = re.compile(r'\+( (?P<data>.*))?')
Flags = re.compile(r'.*FLAGS \((?P<flags>[^\)]*)\)')
InternalDate = re.compile(r'.*INTERNALDATE "'
        r'(?P<day>[ 0123][0-9])-(?P<mon>[A-Z][a-z][a-z])-(?P<year>[0-9][0-9][0-9][0-9])'
        r' (?P<hour>[0-9][0-9]):(?P<min>[0-9][0-9]):(?P<sec>[0-9][0-9])'
        r' (?P<zonen>[-+])(?P<zoneh>[0-9][0-9])(?P<zonem>[0-9][0-9])'
        r'"')
Literal = re.compile(r'.*{(?P<size>\d+)}$')
MapCRLF = re.compile(r'\r\n|\r|\n')
Response_code = re.compile(r'\[(?P<type>[A-Z-]+)( (?P<data>[^\]]*))?\]')
Untagged_response = re.compile(r'\* (?P<type>[A-Z-]+)( (?P<data>.*))?')
Untagged_status = re.compile(r'\* (?P<data>\d+) (?P<type>[A-Z-]+)( (?P<data2>.*))?')



class IMAP4:

    """IMAP4 client class.

    Instantiate with: IMAP4([host[, port]])

            host - host's name (default: localhost);
            port - port number (default: standard IMAP4 port).

    All IMAP4rev1 commands are supported by methods of the same
    name (in lower-case).

    All arguments to commands are converted to strings, except for
    AUTHENTICATE, and the last argument to APPEND which is passed as
    an IMAP4 literal.  If necessary (the string contains any
    non-printing characters or white-space and isn't enclosed with
    either parentheses or double quotes) each string is quoted.
    However, the 'password' argument to the LOGIN command is always
    quoted.  If you want to avoid having an argument string quoted
    (eg: the 'flags' argument to STORE) then enclose the string in
    parentheses (eg: "(\Deleted)").

    Each command returns a tuple: (type, [data, ...]) where 'type'
    is usually 'OK' or 'NO', and 'data' is either the text from the
    tagged response, or untagged results from command. Each 'data'
    is either a string, or a tuple. If a tuple, then the first part
    is the header of the response, and the second part contains
    the data (ie: 'literal' value).

    Errors raise the exception class <instance>.error("<reason>").
    IMAP4 server errors raise <instance>.abort("<reason>"),
    which is a sub-class of 'error'. Mailbox status changes
    from READ-WRITE to READ-ONLY raise the exception class
    <instance>.readonly("<reason>"), which is a sub-class of 'abort'.

    "error" exceptions imply a program error.
    "abort" exceptions imply the connection should be reset, and
            the command re-tried.
    "readonly" exceptions imply the command should be re-tried.

    Note: to use this module, you must read the RFCs pertaining to the
    IMAP4 protocol, as the semantics of the arguments to each IMAP4
    command are left to the invoker, not to mention the results. Also,
    most IMAP servers implement a sub-set of the commands available here.
    """

    class error(Exception): pass    # Logical errors - debug required
    class abort(error): pass        # Service errors - close and retry
    class readonly(abort): pass     # Mailbox status changed to READ-ONLY

    mustquote = re.compile(r"[^\w!#$%&'*+,.:;<=>?^`|~-]")

    def __init__(self, host = '', port = IMAP4_PORT):
        self.debug = Debug
        self.state = 'LOGOUT'
        self.literal = None             # A literal argument to a command
        self.tagged_commands = {}       # Tagged commands awaiting response
        self.untagged_responses = {}    # {typ: [data, ...], ...}
        self.continuation_response = '' # Last continuation response
        self.is_readonly = False        # READ-ONLY desired state
        self.tagnum = 0

        # Open socket to server.

        self.open(host, port)

        # Create unique tag for this session,
        # and compile tagged response matcher.

        self.tagpre = Int2AP(random.randint(4096, 65535))
        self.tagre = re.compile(r'(?P<tag>'
                        + self.tagpre
                        + r'\d+) (?P<type>[A-Z]+) (?P<data>.*)')

        # Get server welcome message,
        # request and store CAPABILITY response.

        if __debug__:
            self._cmd_log_len = 10
            self._cmd_log_idx = 0
            self._cmd_log = {}           # Last `_cmd_log_len' interactions
            if self.debug >= 1:
                self._mesg('imaplib version %s' % __version__)
                self._mesg('new IMAP4 connection, tag=%s' % self.tagpre)

        self.welcome = self._get_response()
        if 'PREAUTH' in self.untagged_responses:
            self.state = 'AUTH'
        elif 'OK' in self.untagged_responses:
            self.state = 'NONAUTH'
        else:
            raise self.error(self.welcome)

        typ, dat = self.capability()
        if dat == [None]:
            raise self.error('no CAPABILITY response from server')
        self.capabilities = tuple(dat[-1].upper().split())

        if __debug__:
            if self.debug >= 3:
                self._mesg('CAPABILITIES: %r' % (self.capabilities,))

        for version in AllowedVersions:
            if not version in self.capabilities:
                continue
            self.PROTOCOL_VERSION = version
            return

        raise self.error('server not IMAP4 compliant')


    def __getattr__(self, attr):
        #       Allow UPPERCASE variants of IMAP4 command methods.
        if attr in Commands:
            return getattr(self, attr.lower())
        raise AttributeError("Unknown IMAP4 command: '%s'" % attr)



    #       Overridable methods


    def open(self, host = '', port = IMAP4_PORT):
        """Setup connection to remote server on "host:port"
            (default: localhost:standard IMAP4 port).
        This connection will be used by the routines:
            read, readline, send, shutdown.
        """
        self.host = host
        self.port = port
        self.sock = socket.create_connection((host, port))
        self.file = self.sock.makefile('rb')


    def read(self, size):
        """Read 'size' bytes from remote."""
        return self.file.read(size)


    def readline(self):
        """Read line from remote."""
        line = self.file.readline(_MAXLINE + 1)
        if len(line) > _MAXLINE:
            raise self.error("got more than %d bytes" % _MAXLINE)
        return line


    def send(self, data):
        """Send data to remote."""
        self.sock.sendall(data)


    def shutdown(self):
        """Close I/O established in "open"."""
        self.file.close()
        try:
            self.sock.shutdown(socket.SHUT_RDWR)
        except socket.error as e:
            # The server might already have closed the connection
            if e.errno != errno.ENOTCONN:
                raise
        finally:
            self.sock.close()


    def socket(self):
        """Return socket instance used to connect to IMAP4 server.

        socket = <instance>.socket()
        """
        return self.sock



    #       Utility methods


    def recent(self):
        """Return most recent 'RECENT' responses if any exist,
        else prompt server for an update using the 'NOOP' command.

        (typ, [data]) = <instance>.recent()

        'data' is None if no new messages,
        else list of RECENT responses, most recent last.
        """
        name = 'RECENT'
        typ, dat = self._untagged_response('OK', [None], name)
        if dat[-1]:
            return typ, dat
        typ, dat = self.noop()  # Prod server for response
        return self._untagged_response(typ, dat, name)


    def response(self, code):
        """Return data for response 'code' if received, or None.

        Old value for response 'code' is cleared.

        (code, [data]) = <instance>.response(code)
        """
        return self._untagged_response(code, [None], code.upper())



    #       IMAP4 commands


    def append(self, mailbox, flags, date_time, message):
        """Append message to named mailbox.

        (typ, [data]) = <instance>.append(mailbox, flags, date_time, message)

                All args except `message' can be None.
        """
        name = 'APPEND'
        if not mailbox:
            mailbox = 'INBOX'
        if flags:
            if (flags[0],flags[-1]) != ('(',')'):
                flags = '(%s)' % flags
        else:
            flags = None
        if date_time:
            date_time = Time2Internaldate(date_time)
        else:
            date_time = None
        self.literal = MapCRLF.sub(CRLF, message)
        return self._simple_command(name, mailbox, flags, date_time)


    def authenticate(self, mechanism, authobject):
        """Authenticate command - requires response processing.

        'mechanism' specifies which authentication mechanism is to
        be used - it must appear in <instance>.capabilities in the
        form AUTH=<mechanism>.

        'authobject' must be a callable object:

                data = authobject(response)

        It will be called to process server continuation responses.
        It should return data that will be encoded and sent to server.
        It should return None if the client abort response '*' should
        be sent instead.
        """
        mech = mechanism.upper()
        # XXX: shouldn't this code be removed, not commented out?
        #cap = 'AUTH=%s' % mech
        #if not cap in self.capabilities:       # Let the server decide!
        #    raise self.error("Server doesn't allow %s authentication." % mech)
        self.literal = _Authenticator(authobject).process
        typ, dat = self._simple_command('AUTHENTICATE', mech)
        if typ != 'OK':
            raise self.error(dat[-1])
        self.state = 'AUTH'
        return typ, dat


    def capability(self):
        """(typ, [data]) = <instance>.capability()
        Fetch capabilities list from server."""

        name = 'CAPABILITY'
        typ, dat = self._simple_command(name)
        return self._untagged_response(typ, dat, name)


    def check(self):
        """Checkpoint mailbox on server.

        (typ, [data]) = <instance>.check()
        """
        return self._simple_command('CHECK')


    def close(self):
        """Close currently selected mailbox.

        Deleted messages are removed from writable mailbox.
        This is the recommended command before 'LOGOUT'.

        (typ, [data]) = <instance>.close()
        """
        try:
            typ, dat = self._simple_command('CLOSE')
        finally:
            self.state = 'AUTH'
        return typ, dat


    def copy(self, message_set, new_mailbox):
        """Copy 'message_set' messages onto end of 'new_mailbox'.

        (typ, [data]) = <instance>.copy(message_set, new_mailbox)
        """
        return self._simple_command('COPY', message_set, new_mailbox)


    def create(self, mailbox):
        """Create new mailbox.

        (typ, [data]) = <instance>.create(mailbox)
        """
        return self._simple_command('CREATE', mailbox)


    def delete(self, mailbox):
        """Delete old mailbox.

        (typ, [data]) = <instance>.delete(mailbox)
        """
        return self._simple_command('DELETE', mailbox)

    def deleteacl(self, mailbox, who):
        """Delete the ACLs (remove any rights) set for who on mailbox.

        (typ, [data]) = <instance>.deleteacl(mailbox, who)
        """
        return self._simple_command('DELETEACL', mailbox, who)

    def expunge(self):
        """Permanently remove deleted items from selected mailbox.

        Generates 'EXPUNGE' response for each deleted message.

        (typ, [data]) = <instance>.expunge()

        'data' is list of 'EXPUNGE'd message numbers in order received.
        """
        name = 'EXPUNGE'
        typ, dat = self._simple_command(name)
        return self._untagged_response(typ, dat, name)


    def fetch(self, message_set, message_parts):
        """Fetch (parts of) messages.

        (typ, [data, ...]) = <instance>.fetch(message_set, message_parts)

        'message_parts' should be a string of selected parts
        enclosed in parentheses, eg: "(UID BODY[TEXT])".

        'data' are tuples of message part envelope and data.
        """
        name = 'FETCH'
        typ, dat = self._simple_command(name, message_set, message_parts)
        return self._untagged_response(typ, dat, name)


    def getacl(self, mailbox):
        """Get the ACLs for a mailbox.

        (typ, [data]) = <instance>.getacl(mailbox)
        """
        typ, dat = self._simple_command('GETACL', mailbox)
        return self._untagged_response(typ, dat, 'ACL')


    def getannotation(self, mailbox, entry, attribute):
        """(typ, [data]) = <instance>.getannotation(mailbox, entry, attribute)
        Retrieve ANNOTATIONs."""

        typ, dat = self._simple_command('GETANNOTATION', mailbox, entry, attribute)
        return self._untagged_response(typ, dat, 'ANNOTATION')


    def getquota(self, root):
        """Get the quota root's resource usage and limits.

        Part of the IMAP4 QUOTA extension defined in rfc2087.

        (typ, [data]) = <instance>.getquota(root)
        """
        typ, dat = self._simple_command('GETQUOTA', root)
        return self._untagged_response(typ, dat, 'QUOTA')


    def getquotaroot(self, mailbox):
        """Get the list of quota roots for the named mailbox.

        (typ, [[QUOTAROOT responses...], [QUOTA responses]]) = <instance>.getquotaroot(mailbox)
        """
        typ, dat = self._simple_command('GETQUOTAROOT', mailbox)
        typ, quota = self._untagged_response(typ, dat, 'QUOTA')
        typ, quotaroot = self._untagged_response(typ, dat, 'QUOTAROOT')
        return typ, [quotaroot, quota]


    def list(self, directory='""', pattern='*'):
        """List mailbox names in directory matching pattern.

        (typ, [data]) = <instance>.list(directory='""', pattern='*')

        'data' is list of LIST responses.
        """
        name = 'LIST'
        typ, dat = self._simple_command(name, directory, pattern)
        return self._untagged_response(typ, dat, name)


    def login(self, user, password):
        """Identify client using plaintext password.

        (typ, [data]) = <instance>.login(user, password)

        NB: 'password' will be quoted.
        """
        typ, dat = self._simple_command('LOGIN', user, self._quote(password))
        if typ != 'OK':
            raise self.error(dat[-1])
        self.state = 'AUTH'
        return typ, dat


    def login_cram_md5(self, user, password):
        """ Force use of CRAM-MD5 authentication.

        (typ, [data]) = <instance>.login_cram_md5(user, password)
        """
        self.user, self.password = user, password
        return self.authenticate('CRAM-MD5', self._CRAM_MD5_AUTH)


    def _CRAM_MD5_AUTH(self, challenge):
        """ Authobject to use with CRAM-MD5 authentication. """
        import hmac
        return self.user + " " + hmac.HMAC(self.password, challenge).hexdigest()


    def logout(self):
        """Shutdown connection to server.

        (typ, [data]) = <instance>.logout()

        Returns server 'BYE' response.
        """
        self.state = 'LOGOUT'
        try: typ, dat = self._simple_command('LOGOUT')
        except: typ, dat = 'NO', ['%s: %s' % sys.exc_info()[:2]]
        self.shutdown()
        if 'BYE' in self.untagged_responses:
            return 'BYE', self.untagged_responses['BYE']
        return typ, dat


    def lsub(self, directory='""', pattern='*'):
        """List 'subscribed' mailbox names in directory matching pattern.

        (typ, [data, ...]) = <instance>.lsub(directory='""', pattern='*')

        'data' are tuples of message part envelope and data.
        """
        name = 'LSUB'
        typ, dat = self._simple_command(name, directory, pattern)
        return self._untagged_response(typ, dat, name)

    def myrights(self, mailbox):
        """Show my ACLs for a mailbox (i.e. the rights that I have on mailbox).

        (typ, [data]) = <instance>.myrights(mailbox)
        """
        typ,dat = self._simple_command('MYRIGHTS', mailbox)
        return self._untagged_response(typ, dat, 'MYRIGHTS')

    def namespace(self):
        """ Returns IMAP namespaces ala rfc2342

        (typ, [data, ...]) = <instance>.namespace()
        """
        name = 'NAMESPACE'
        typ, dat = self._simple_command(name)
        return self._untagged_response(typ, dat, name)


    def noop(self):
        """Send NOOP command.

        (typ, [data]) = <instance>.noop()
        """
        if __debug__:
            if self.debug >= 3:
                self._dump_ur(self.untagged_responses)
        return self._simple_command('NOOP')


    def partial(self, message_num, message_part, start, length):
        """Fetch truncated part of a message.

        (typ, [data, ...]) = <instance>.partial(message_num, message_part, start, length)

        'data' is tuple of message part envelope and data.
        """
        name = 'PARTIAL'
        typ, dat = self._simple_command(name, message_num, message_part, start, length)
        return self._untagged_response(typ, dat, 'FETCH')


    def proxyauth(self, user):
        """Assume authentication as "user".

        Allows an authorised administrator to proxy into any user's
        mailbox.

        (typ, [data]) = <instance>.proxyauth(user)
        """

        name = 'PROXYAUTH'
        return self._simple_command('PROXYAUTH', user)


    def rename(self, oldmailbox, newmailbox):
        """Rename old mailbox name to new.

        (typ, [data]) = <instance>.rename(oldmailbox, newmailbox)
        """
        return self._simple_command('RENAME', oldmailbox, newmailbox)


    def search(self, charset, *criteria):
        """Search mailbox for matching messages.

        (typ, [data]) = <instance>.search(charset, criterion, ...)

        'data' is space separated list of matching message numbers.
        """
        name = 'SEARCH'
        if charset:
            typ, dat = self._simple_command(name, 'CHARSET', charset, *criteria)
        else:
            typ, dat = self._simple_command(name, *criteria)
        return self._untagged_response(typ, dat, name)


    def select(self, mailbox='INBOX', readonly=False):
        """Select a mailbox.

        Flush all untagged responses.

        (typ, [data]) = <instance>.select(mailbox='INBOX', readonly=False)

        'data' is count of messages in mailbox ('EXISTS' response).

        Mandated responses are ('FLAGS', 'EXISTS', 'RECENT', 'UIDVALIDITY'), so
        other responses should be obtained via <instance>.response('FLAGS') etc.
        """
        self.untagged_responses = {}    # Flush old responses.
        self.is_readonly = readonly
        if readonly:
            name = 'EXAMINE'
        else:
            name = 'SELECT'
        typ, dat = self._simple_command(name, mailbox)
        if typ != 'OK':
            self.state = 'AUTH'     # Might have been 'SELECTED'
            return typ, dat
        self.state = 'SELECTED'
        if 'READ-ONLY' in self.untagged_responses \
                and not readonly:
            if __debug__:
                if self.debug >= 1:
                    self._dump_ur(self.untagged_responses)
            raise self.readonly('%s is not writable' % mailbox)
        return typ, self.untagged_responses.get('EXISTS', [None])


    def setacl(self, mailbox, who, what):
        """Set a mailbox acl.

        (typ, [data]) = <instance>.setacl(mailbox, who, what)
        """
        return self._simple_command('SETACL', mailbox, who, what)


    def setannotation(self, *args):
        """(typ, [data]) = <instance>.setannotation(mailbox[, entry, attribute]+)
        Set ANNOTATIONs."""

        typ, dat = self._simple_command('SETANNOTATION', *args)
        return self._untagged_response(typ, dat, 'ANNOTATION')


    def setquota(self, root, limits):
        """Set the quota root's resource limits.

        (typ, [data]) = <instance>.setquota(root, limits)
        """
        typ, dat = self._simple_command('SETQUOTA', root, limits)
        return self._untagged_response(typ, dat, 'QUOTA')


    def sort(self, sort_criteria, charset, *search_criteria):
        """IMAP4rev1 extension SORT command.

        (typ, [data]) = <instance>.sort(sort_criteria, charset, search_criteria, ...)
        """
        name = 'SORT'
        #if not name in self.capabilities:      # Let the server decide!
        #       raise self.error('unimplemented extension command: %s' % name)
        if (sort_criteria[0],sort_criteria[-1]) != ('(',')'):
            sort_criteria = '(%s)' % sort_criteria
        typ, dat = self._simple_command(name, sort_criteria, charset, *search_criteria)
        return self._untagged_response(typ, dat, name)


    def status(self, mailbox, names):
        """Request named status conditions for mailbox.

        (typ, [data]) = <instance>.status(mailbox, names)
        """
        name = 'STATUS'
        #if self.PROTOCOL_VERSION == 'IMAP4':   # Let the server decide!
        #    raise self.error('%s unimplemented in IMAP4 (obtain IMAP4rev1 server, or re-code)' % name)
        typ, dat = self._simple_command(name, mailbox, names)
        return self._untagged_response(typ, dat, name)


    def store(self, message_set, command, flags):
        """Alters flag dispositions for messages in mailbox.

        (typ, [data]) = <instance>.store(message_set, command, flags)
        """
        if (flags[0],flags[-1]) != ('(',')'):
            flags = '(%s)' % flags  # Avoid quoting the flags
        typ, dat = self._simple_command('STORE', message_set, command, flags)
        return self._untagged_response(typ, dat, 'FETCH')


    def subscribe(self, mailbox):
        """Subscribe to new mailbox.

        (typ, [data]) = <instance>.subscribe(mailbox)
        """
        return self._simple_command('SUBSCRIBE', mailbox)


    def thread(self, threading_algorithm, charset, *search_criteria):
        """IMAPrev1 extension THREAD command.

        (type, [data]) = <instance>.thread(threading_algorithm, charset, search_criteria, ...)
        """
        name = 'THREAD'
        typ, dat = self._simple_command(name, threading_algorithm, charset, *search_criteria)
        return self._untagged_response(typ, dat, name)


    def uid(self, command, *args):
        """Execute "command arg ..." with messages identified by UID,
                rather than message number.

        (typ, [data]) = <instance>.uid(command, arg1, arg2, ...)

        Returns response appropriate to 'command'.
        """
        command = command.upper()
        if not command in Commands:
            raise self.error("Unknown IMAP4 UID command: %s" % command)
        if self.state not in Commands[command]:
            raise self.error("command %s illegal in state %s, "
                             "only allowed in states %s" %
                             (command, self.state,
                              ', '.join(Commands[command])))
        name = 'UID'
        typ, dat = self._simple_command(name, command, *args)
        if command in ('SEARCH', 'SORT', 'THREAD'):
            name = command
        else:
            name = 'FETCH'
        return self._untagged_response(typ, dat, name)


    def unsubscribe(self, mailbox):
        """Unsubscribe from old mailbox.

        (typ, [data]) = <instance>.unsubscribe(mailbox)
        """
        return self._simple_command('UNSUBSCRIBE', mailbox)


    def xatom(self, name, *args):
        """Allow simple extension commands
                notified by server in CAPABILITY response.

        Assumes command is legal in current state.

        (typ, [data]) = <instance>.xatom(name, arg, ...)

        Returns response appropriate to extension command `name'.
        """
        name = name.upper()
        #if not name in self.capabilities:      # Let the server decide!
        #    raise self.error('unknown extension command: %s' % name)
        if not name in Commands:
            Commands[name] = (self.state,)
        return self._simple_command(name, *args)



    #       Private methods


    def _append_untagged(self, typ, dat):

        if dat is None: dat = ''
        ur = self.untagged_responses
        if __debug__:
            if self.debug >= 5:
                self._mesg('untagged_responses[%s] %s += ["%s"]' %
                        (typ, len(ur.get(typ,'')), dat))
        if typ in ur:
            ur[typ].append(dat)
        else:
            ur[typ] = [dat]


    def _check_bye(self):
        bye = self.untagged_responses.get('BYE')
        if bye:
            raise self.abort(bye[-1])


    def _command(self, name, *args):

        if self.state not in Commands[name]:
            self.literal = None
            raise self.error("command %s illegal in state %s, "
                             "only allowed in states %s" %
                             (name, self.state,
                              ', '.join(Commands[name])))

        for typ in ('OK', 'NO', 'BAD'):
            if typ in self.untagged_responses:
                del self.untagged_responses[typ]

        if 'READ-ONLY' in self.untagged_responses \
        and not self.is_readonly:
            raise self.readonly('mailbox status changed to READ-ONLY')

        tag = self._new_tag()
        data = '%s %s' % (tag, name)
        for arg in args:
            if arg is None: continue
            data = '%s %s' % (data, self._checkquote(arg))

        literal = self.literal
        if literal is not None:
            self.literal = None
            if type(literal) is type(self._command):
                literator = literal
            else:
                literator = None
                data = '%s {%s}' % (data, len(literal))

        if __debug__:
            if self.debug >= 4:
                self._mesg('> %s' % data)
            else:
                self._log('> %s' % data)

        try:
            self.send('%s%s' % (data, CRLF))
        except (socket.error, OSError), val:
            raise self.abort('socket error: %s' % val)

        if literal is None:
            return tag

        while 1:
            # Wait for continuation response

            while self._get_response():
                if self.tagged_commands[tag]:   # BAD/NO?
                    return tag

            # Send literal

            if literator:
                literal = literator(self.continuation_response)

            if __debug__:
                if self.debug >= 4:
                    self._mesg('write literal size %s' % len(literal))

            try:
                self.send(literal)
                self.send(CRLF)
            except (socket.error, OSError), val:
                raise self.abort('socket error: %s' % val)

            if not literator:
                break

        return tag


    def _command_complete(self, name, tag):
        # BYE is expected after LOGOUT
        if name != 'LOGOUT':
            self._check_bye()
        try:
            typ, data = self._get_tagged_response(tag)
        except self.abort, val:
            raise self.abort('command: %s => %s' % (name, val))
        except self.error, val:
            raise self.error('command: %s => %s' % (name, val))
        if name != 'LOGOUT':
            self._check_bye()
        if typ == 'BAD':
            raise self.error('%s command error: %s %s' % (name, typ, data))
        return typ, data


    def _get_response(self):

        # Read response and store.
        #
        # Returns None for continuation responses,
        # otherwise first response line received.

        resp = self._get_line()

        # Command completion response?

        if self._match(self.tagre, resp):
            tag = self.mo.group('tag')
            if not tag in self.tagged_commands:
                raise self.abort('unexpected tagged response: %s' % resp)

            typ = self.mo.group('type')
            dat = self.mo.group('data')
            self.tagged_commands[tag] = (typ, [dat])
        else:
            dat2 = None

            # '*' (untagged) responses?

            if not self._match(Untagged_response, resp):
                if self._match(Untagged_status, resp):
                    dat2 = self.mo.group('data2')

            if self.mo is None:
                # Only other possibility is '+' (continuation) response...

                if self._match(Continuation, resp):
                    self.continuation_response = self.mo.group('data')
                    return None     # NB: indicates continuation

                raise self.abort("unexpected response: '%s'" % resp)

            typ = self.mo.group('type')
            dat = self.mo.group('data')
            if dat is None: dat = ''        # Null untagged response
            if dat2: dat = dat + ' ' + dat2

            # Is there a literal to come?

            while self._match(Literal, dat):

                # Read literal direct from connection.

                size = int(self.mo.group('size'))
                if __debug__:
                    if self.debug >= 4:
                        self._mesg('read literal size %s' % size)
                data = self.read(size)

                # Store response with literal as tuple

                self._append_untagged(typ, (dat, data))

                # Read trailer - possibly containing another literal

                dat = self._get_line()

            self._append_untagged(typ, dat)

        # Bracketed response information?

        if typ in ('OK', 'NO', 'BAD') and self._match(Response_code, dat):
            self._append_untagged(self.mo.group('type'), self.mo.group('data'))

        if __debug__:
            if self.debug >= 1 and typ in ('NO', 'BAD', 'BYE'):
                self._mesg('%s response: %s' % (typ, dat))

        return resp


    def _get_tagged_response(self, tag):

        while 1:
            result = self.tagged_commands[tag]
            if result is not None:
                del self.tagged_commands[tag]
                return result

            # If we've seen a BYE at this point, the socket will be
            # closed, so report the BYE now.

            self._check_bye()

            # Some have reported "unexpected response" exceptions.
            # Note that ignoring them here causes loops.
            # Instead, send me details of the unexpected response and
            # I'll update the code in `_get_response()'.

            try:
                self._get_response()
            except self.abort, val:
                if __debug__:
                    if self.debug >= 1:
                        self.print_log()
                raise


    def _get_line(self):

        line = self.readline()
        if not line:
            raise self.abort('socket error: EOF')

        # Protocol mandates all lines terminated by CRLF
        if not line.endswith('\r\n'):
            raise self.abort('socket error: unterminated line')

        line = line[:-2]
        if __debug__:
            if self.debug >= 4:
                self._mesg('< %s' % line)
            else:
                self._log('< %s' % line)
        return line


    def _match(self, cre, s):

        # Run compiled regular expression match method on 's'.
        # Save result, return success.

        self.mo = cre.match(s)
        if __debug__:
            if self.mo is not None and self.debug >= 5:
                self._mesg("\tmatched r'%s' => %r" % (cre.pattern, self.mo.groups()))
        return self.mo is not None


    def _new_tag(self):

        tag = '%s%s' % (self.tagpre, self.tagnum)
        self.tagnum = self.tagnum + 1
        self.tagged_commands[tag] = None
        return tag


    def _checkquote(self, arg):

        # Must quote command args if non-alphanumeric chars present,
        # and not already quoted.

        if type(arg) is not type(''):
            return arg
        if len(arg) >= 2 and (arg[0],arg[-1]) in (('(',')'),('"','"')):
            return arg
        if arg and self.mustquote.search(arg) is None:
            return arg
        return self._quote(arg)


    def _quote(self, arg):

        arg = arg.replace('\\', '\\\\')
        arg = arg.replace('"', '\\"')

        return '"%s"' % arg


    def _simple_command(self, name, *args):

        return self._command_complete(name, self._command(name, *args))


    def _untagged_response(self, typ, dat, name):

        if typ == 'NO':
            return typ, dat
        if not name in self.untagged_responses:
            return typ, [None]
        data = self.untagged_responses.pop(name)
        if __debug__:
            if self.debug >= 5:
                self._mesg('untagged_responses[%s] => %s' % (name, data))
        return typ, data


    if __debug__:

        def _mesg(self, s, secs=None):
            if secs is None:
                secs = time.time()
            tm = time.strftime('%M:%S', time.localtime(secs))
            sys.stderr.write('  %s.%02d %s\n' % (tm, (secs*100)%100, s))
            sys.stderr.flush()

        def _dump_ur(self, dict):
            # Dump untagged responses (in `dict').
            l = dict.items()
            if not l: return
            t = '\n\t\t'
            l = map(lambda x:'%s: "%s"' % (x[0], x[1][0] and '" "'.join(x[1]) or ''), l)
            self._mesg('untagged responses dump:%s%s' % (t, t.join(l)))

        def _log(self, line):
            # Keep log of last `_cmd_log_len' interactions for debugging.
            self._cmd_log[self._cmd_log_idx] = (line, time.time())
            self._cmd_log_idx += 1
            if self._cmd_log_idx >= self._cmd_log_len:
                self._cmd_log_idx = 0

        def print_log(self):
            self._mesg('last %d IMAP4 interactions:' % len(self._cmd_log))
            i, n = self._cmd_log_idx, self._cmd_log_len
            while n:
                try:
                    self._mesg(*self._cmd_log[i])
                except:
                    pass
                i += 1
                if i >= self._cmd_log_len:
                    i = 0
                n -= 1



try:
    import ssl
except ImportError:
    pass
else:
    class IMAP4_SSL(IMAP4):

        """IMAP4 client class over SSL connection

        Instantiate with: IMAP4_SSL([host[, port[, keyfile[, certfile]]]])

                host - host's name (default: localhost);
                port - port number (default: standard IMAP4 SSL port).
                keyfile - PEM formatted file that contains your private key (default: None);
                certfile - PEM formatted certificate chain file (default: None);

        for more documentation see the docstring of the parent class IMAP4.
        """


        def __init__(self, host = '', port = IMAP4_SSL_PORT, keyfile = None, certfile = None):
            self.keyfile = keyfile
            self.certfile = certfile
            IMAP4.__init__(self, host, port)


        def open(self, host = '', port = IMAP4_SSL_PORT):
            """Setup connection to remote server on "host:port".
                (default: localhost:standard IMAP4 SSL port).
            This connection will be used by the routines:
                read, readline, send, shutdown.
            """
            self.host = host
            self.port = port
            self.sock = socket.create_connection((host, port))
            self.sslobj = ssl.wrap_socket(self.sock, self.keyfile, self.certfile)
            self.file = self.sslobj.makefile('rb')


        def read(self, size):
            """Read 'size' bytes from remote."""
            return self.file.read(size)


        def readline(self):
            """Read line from remote."""
            return self.file.readline()


        def send(self, data):
            """Send data to remote."""
            bytes = len(data)
            while bytes > 0:
                sent = self.sslobj.write(data)
                if sent == bytes:
                    break    # avoid copy
                data = data[sent:]
                bytes = bytes - sent


        def shutdown(self):
            """Close I/O established in "open"."""
            self.file.close()
            self.sock.close()


        def socket(self):
            """Return socket instance used to connect to IMAP4 server.

            socket = <instance>.socket()
            """
            return self.sock


        def ssl(self):
            """Return SSLObject instance used to communicate with the IMAP4 server.

            ssl = ssl.wrap_socket(<instance>.socket)
            """
            return self.sslobj

    __all__.append("IMAP4_SSL")


class IMAP4_stream(IMAP4):

    """IMAP4 client class over a stream

    Instantiate with: IMAP4_stream(command)

            where "command" is a string that can be passed to subprocess.Popen()

    for more documentation see the docstring of the parent class IMAP4.
    """


    def __init__(self, command):
        self.command = command
        IMAP4.__init__(self)


    def open(self, host = None, port = None):
        """Setup a stream connection.
        This connection will be used by the routines:
            read, readline, send, shutdown.
        """
        self.host = None        # For compatibility with parent class
        self.port = None
        self.sock = None
        self.file = None
        self.process = subprocess.Popen(self.command,
            stdin=subprocess.PIPE, stdout=subprocess.PIPE,
            shell=True, close_fds=True)
        self.writefile = self.process.stdin
        self.readfile = self.process.stdout


    def read(self, size):
        """Read 'size' bytes from remote."""
        return self.readfile.read(size)


    def readline(self):
        """Read line from remote."""
        return self.readfile.readline()


    def send(self, data):
        """Send data to remote."""
        self.writefile.write(data)
        self.writefile.flush()


    def shutdown(self):
        """Close I/O established in "open"."""
        self.readfile.close()
        self.writefile.close()
        self.process.wait()



class _Authenticator:

    """Private class to provide en/decoding
            for base64-based authentication conversation.
    """

    def __init__(self, mechinst):
        self.mech = mechinst    # Callable object to provide/process data

    def process(self, data):
        ret = self.mech(self.decode(data))
        if ret is None:
            return '*'      # Abort conversation
        return self.encode(ret)

    def encode(self, inp):
        #
        #  Invoke binascii.b2a_base64 iteratively with
        #  short even length buffers, strip the trailing
        #  line feed from the result and append.  "Even"
        #  means a number that factors to both 6 and 8,
        #  so when it gets to the end of the 8-bit input
        #  there's no partial 6-bit output.
        #
        oup = ''
        while inp:
            if len(inp) > 48:
                t = inp[:48]
                inp = inp[48:]
            else:
                t = inp
                inp = ''
            e = binascii.b2a_base64(t)
            if e:
                oup = oup + e[:-1]
        return oup

    def decode(self, inp):
        if not inp:
            return ''
        return binascii.a2b_base64(inp)



Mon2num = {'Jan': 1, 'Feb': 2, 'Mar': 3, 'Apr': 4, 'May': 5, 'Jun': 6,
        'Jul': 7, 'Aug': 8, 'Sep': 9, 'Oct': 10, 'Nov': 11, 'Dec': 12}

def Internaldate2tuple(resp):
    """Parse an IMAP4 INTERNALDATE string.

    Return corresponding local time.  The return value is a
    time.struct_time instance or None if the string has wrong format.
    """

    mo = InternalDate.match(resp)
    if not mo:
        return None

    mon = Mon2num[mo.group('mon')]
    zonen = mo.group('zonen')

    day = int(mo.group('day'))
    year = int(mo.group('year'))
    hour = int(mo.group('hour'))
    min = int(mo.group('min'))
    sec = int(mo.group('sec'))
    zoneh = int(mo.group('zoneh'))
    zonem = int(mo.group('zonem'))

    # INTERNALDATE timezone must be subtracted to get UT

    zone = (zoneh*60 + zonem)*60
    if zonen == '-':
        zone = -zone

    tt = (year, mon, day, hour, min, sec, -1, -1, -1)

    utc = time.mktime(tt)

    # Following is necessary because the time module has no 'mkgmtime'.
    # 'mktime' assumes arg in local timezone, so adds timezone/altzone.

    lt = time.localtime(utc)
    if time.daylight and lt[-1]:
        zone = zone + time.altzone
    else:
        zone = zone + time.timezone

    return time.localtime(utc - zone)



def Int2AP(num):

    """Convert integer to A-P string representation."""

    val = ''; AP = 'ABCDEFGHIJKLMNOP'
    num = int(abs(num))
    while num:
        num, mod = divmod(num, 16)
        val = AP[mod] + val
    return val



def ParseFlags(resp):

    """Convert IMAP4 flags response to python tuple."""

    mo = Flags.match(resp)
    if not mo:
        return ()

    return tuple(mo.group('flags').split())


def Time2Internaldate(date_time):

    """Convert date_time to IMAP4 INTERNALDATE representation.

    Return string in form: '"DD-Mmm-YYYY HH:MM:SS +HHMM"'.  The
    date_time argument can be a number (int or float) representing
    seconds since epoch (as returned by time.time()), a 9-tuple
    representing local time (as returned by time.localtime()), or a
    double-quoted string.  In the last case, it is assumed to already
    be in the correct format.
    """

    if isinstance(date_time, (int, float)):
        tt = time.localtime(date_time)
    elif isinstance(date_time, (tuple, time.struct_time)):
        tt = date_time
    elif isinstance(date_time, str) and (date_time[0],date_time[-1]) == ('"','"'):
        return date_time        # Assume in correct format
    else:
        raise ValueError("date_time not of a known type")

    dt = time.strftime("%d-%b-%Y %H:%M:%S", tt)
    if dt[0] == '0':
        dt = ' ' + dt[1:]
    if time.daylight and tt[-1]:
        zone = -time.altzone
    else:
        zone = -time.timezone
    return '"' + dt + " %+03d%02d" % divmod(zone//60, 60) + '"'



if __name__ == '__main__':

    # To test: invoke either as 'python imaplib.py [IMAP4_server_hostname]'
    # or 'python imaplib.py -s "rsh IMAP4_server_hostname exec /etc/rimapd"'
    # to test the IMAP4_stream class

    import getopt, getpass

    try:
        optlist, args = getopt.getopt(sys.argv[1:], 'd:s:')
    except getopt.error, val:
        optlist, args = (), ()

    stream_command = None
    for opt,val in optlist:
        if opt == '-d':
            Debug = int(val)
        elif opt == '-s':
            stream_command = val
            if not args: args = (stream_command,)

    if not args: args = ('',)

    host = args[0]

    USER = getpass.getuser()
    PASSWD = getpass.getpass("IMAP password for %s on %s: " % (USER, host or "localhost"))

    test_mesg = 'From: %(user)s@localhost%(lf)sSubject: IMAP4 test%(lf)s%(lf)sdata...%(lf)s' % {'user':USER, 'lf':'\n'}
    test_seq1 = (
    ('login', (USER, PASSWD)),
    ('create', ('/tmp/xxx 1',)),
    ('rename', ('/tmp/xxx 1', '/tmp/yyy')),
    ('CREATE', ('/tmp/yyz 2',)),
    ('append', ('/tmp/yyz 2', None, None, test_mesg)),
    ('list', ('/tmp', 'yy*')),
    ('select', ('/tmp/yyz 2',)),
    ('search', (None, 'SUBJECT', 'test')),
    ('fetch', ('1', '(FLAGS INTERNALDATE RFC822)')),
    ('store', ('1', 'FLAGS', '(\Deleted)')),
    ('namespace', ()),
    ('expunge', ()),
    ('recent', ()),
    ('close', ()),
    )

    test_seq2 = (
    ('select', ()),
    ('response',('UIDVALIDITY',)),
    ('uid', ('SEARCH', 'ALL')),
    ('response', ('EXISTS',)),
    ('append', (None, None, None, test_mesg)),
    ('recent', ()),
    ('logout', ()),
    )

    def run(cmd, args):
        M._mesg('%s %s' % (cmd, args))
        typ, dat = getattr(M, cmd)(*args)
        M._mesg('%s => %s %s' % (cmd, typ, dat))
        if typ == 'NO': raise dat[0]
        return dat

    try:
        if stream_command:
            M = IMAP4_stream(stream_command)
        else:
            M = IMAP4(host)
        if M.state == 'AUTH':
            test_seq1 = test_seq1[1:]   # Login not needed
        M._mesg('PROTOCOL_VERSION = %s' % M.PROTOCOL_VERSION)
        M._mesg('CAPABILITIES = %r' % (M.capabilities,))

        for cmd,args in test_seq1:
            run(cmd, args)

        for ml in run('list', ('/tmp/', 'yy%')):
            mo = re.match(r'.*"([^"]+)"$', ml)
            if mo: path = mo.group(1)
            else: path = ml.split()[-1]
            run('delete', (path,))

        for cmd,args in test_seq2:
            dat = run(cmd, args)

            if (cmd,args) != ('uid', ('SEARCH', 'ALL')):
                continue

            uid = dat[-1].split()
            if not uid: continue
            run('uid', ('FETCH', '%s' % uid[-1],
                    '(FLAGS INTERNALDATE RFC822.SIZE RFC822.HEADER RFC822.TEXT)'))

        print '\nAll tests OK.'

    except:
        print '\nTests failed.'

        if not Debug:
            print '''
If you would like to see debugging output,
try: %s -d5
''' % sys.argv[0]

        raise