aboutsummaryrefslogtreecommitdiff
path: root/lib/imap.c
blob: c257d76ccb236df2b7b1739ea241f477bd8fd8a4 (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
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
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
2230
2231
2232
2233
2234
2235
2236
2237
2238
2239
2240
2241
2242
2243
2244
2245
2246
2247
2248
2249
2250
2251
2252
2253
2254
2255
2256
2257
2258
2259
2260
2261
2262
2263
2264
2265
2266
2267
2268
2269
2270
2271
2272
2273
2274
2275
2276
2277
2278
2279
2280
2281
2282
2283
2284
2285
2286
2287
2288
2289
2290
2291
2292
2293
2294
2295
2296
2297
2298
2299
2300
2301
2302
2303
2304
2305
2306
2307
2308
2309
2310
2311
2312
2313
2314
2315
2316
2317
2318
2319
2320
2321
2322
2323
2324
2325
2326
2327
2328
2329
2330
2331
2332
2333
2334
2335
2336
2337
2338
2339
2340
2341
2342
2343
2344
2345
2346
2347
2348
2349
2350
2351
2352
2353
2354
2355
2356
2357
2358
2359
2360
2361
2362
2363
2364
2365
2366
2367
2368
2369
2370
2371
2372
2373
2374
2375
2376
2377
2378
2379
2380
2381
2382
2383
2384
2385
2386
2387
2388
2389
2390
2391
2392
2393
2394
2395
2396
2397
2398
2399
2400
2401
2402
2403
2404
2405
2406
2407
2408
2409
2410
2411
2412
2413
2414
2415
2416
2417
2418
2419
2420
2421
2422
2423
2424
2425
2426
2427
2428
2429
2430
2431
2432
2433
2434
2435
2436
2437
2438
2439
2440
2441
2442
2443
2444
2445
2446
2447
2448
2449
2450
2451
2452
2453
2454
2455
2456
2457
2458
2459
2460
2461
2462
2463
2464
2465
2466
2467
2468
2469
2470
2471
2472
2473
2474
2475
2476
2477
2478
2479
2480
2481
2482
2483
2484
2485
2486
2487
2488
2489
2490
2491
2492
2493
2494
2495
2496
2497
2498
2499
2500
2501
2502
2503
2504
2505
2506
2507
2508
2509
2510
2511
2512
2513
2514
2515
2516
2517
2518
2519
2520
2521
2522
2523
2524
2525
2526
2527
/***************************************************************************
 *                                  _   _ ____  _
 *  Project                     ___| | | |  _ \| |
 *                             / __| | | | |_) | |
 *                            | (__| |_| |  _ <| |___
 *                             \___|\___/|_| \_\_____|
 *
 * Copyright (C) 1998 - 2013, Daniel Stenberg, <daniel@haxx.se>, et al.
 *
 * This software is licensed as described in the file COPYING, which
 * you should have received as part of this distribution. The terms
 * are also available at http://curl.haxx.se/docs/copyright.html.
 *
 * You may opt to use, copy, modify, merge, publish, distribute and/or sell
 * copies of the Software, and permit persons to whom the Software is
 * furnished to do so, under the terms of the COPYING file.
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
 * KIND, either express or implied.
 *
 * RFC2195 CRAM-MD5 authentication
 * RFC2595 Using TLS with IMAP, POP3 and ACAP
 * RFC2831 DIGEST-MD5 authentication
 * RFC3501 IMAPv4 protocol
 * RFC4422 Simple Authentication and Security Layer (SASL)
 * RFC4616 PLAIN authentication
 * RFC4959 IMAP Extension for SASL Initial Client Response
 * RFC5092 IMAP URL Scheme
 * RFC6749 OAuth 2.0 Authorization Framework
 * Draft   LOGIN SASL Mechanism <draft-murchison-sasl-login-00.txt>
 *
 ***************************************************************************/

#include "curl_setup.h"

#ifndef CURL_DISABLE_IMAP

#ifdef HAVE_NETINET_IN_H
#include <netinet/in.h>
#endif
#ifdef HAVE_ARPA_INET_H
#include <arpa/inet.h>
#endif
#ifdef HAVE_UTSNAME_H
#include <sys/utsname.h>
#endif
#ifdef HAVE_NETDB_H
#include <netdb.h>
#endif
#ifdef __VMS
#include <in.h>
#include <inet.h>
#endif

#if (defined(NETWARE) && defined(__NOVELL_LIBC__))
#undef in_addr_t
#define in_addr_t unsigned long
#endif

#include <curl/curl.h>
#include "urldata.h"
#include "sendf.h"
#include "if2ip.h"
#include "hostip.h"
#include "progress.h"
#include "transfer.h"
#include "escape.h"
#include "http.h" /* for HTTP proxy tunnel stuff */
#include "socks.h"
#include "imap.h"

#include "strtoofft.h"
#include "strequal.h"
#include "sslgen.h"
#include "connect.h"
#include "strerror.h"
#include "select.h"
#include "multiif.h"
#include "url.h"
#include "rawstr.h"
#include "curl_sasl.h"
#include "warnless.h"

#define _MPRINTF_REPLACE /* use our functions only */
#include <curl/mprintf.h>

#include "curl_memory.h"
/* The last #include file should be: */
#include "memdebug.h"

/* Local API functions */
static CURLcode imap_regular_transfer(struct connectdata *conn, bool *done);
static CURLcode imap_do(struct connectdata *conn, bool *done);
static CURLcode imap_done(struct connectdata *conn, CURLcode status,
                          bool premature);
static CURLcode imap_connect(struct connectdata *conn, bool *done);
static CURLcode imap_disconnect(struct connectdata *conn, bool dead);
static CURLcode imap_multi_statemach(struct connectdata *conn, bool *done);
static int imap_getsock(struct connectdata *conn, curl_socket_t *socks,
                        int numsocks);
static CURLcode imap_doing(struct connectdata *conn, bool *dophase_done);
static CURLcode imap_setup_connection(struct connectdata *conn);
static char *imap_atom(const char *str);
static CURLcode imap_sendf(struct connectdata *conn, const char *fmt, ...);
static CURLcode imap_parse_url_options(struct connectdata *conn);
static CURLcode imap_parse_url_path(struct connectdata *conn);
static CURLcode imap_parse_custom_request(struct connectdata *conn);

/*
 * IMAP protocol handler.
 */

const struct Curl_handler Curl_handler_imap = {
  "IMAP",                           /* scheme */
  imap_setup_connection,            /* setup_connection */
  imap_do,                          /* do_it */
  imap_done,                        /* done */
  ZERO_NULL,                        /* do_more */
  imap_connect,                     /* connect_it */
  imap_multi_statemach,             /* connecting */
  imap_doing,                       /* doing */
  imap_getsock,                     /* proto_getsock */
  imap_getsock,                     /* doing_getsock */
  ZERO_NULL,                        /* domore_getsock */
  ZERO_NULL,                        /* perform_getsock */
  imap_disconnect,                  /* disconnect */
  ZERO_NULL,                        /* readwrite */
  PORT_IMAP,                        /* defport */
  CURLPROTO_IMAP,                   /* protocol */
  PROTOPT_CLOSEACTION | PROTOPT_NEEDSPWD
  | PROTOPT_NOURLQUERY              /* flags */
};

#ifdef USE_SSL
/*
 * IMAPS protocol handler.
 */

const struct Curl_handler Curl_handler_imaps = {
  "IMAPS",                          /* scheme */
  imap_setup_connection,            /* setup_connection */
  imap_do,                          /* do_it */
  imap_done,                        /* done */
  ZERO_NULL,                        /* do_more */
  imap_connect,                     /* connect_it */
  imap_multi_statemach,             /* connecting */
  imap_doing,                       /* doing */
  imap_getsock,                     /* proto_getsock */
  imap_getsock,                     /* doing_getsock */
  ZERO_NULL,                        /* domore_getsock */
  ZERO_NULL,                        /* perform_getsock */
  imap_disconnect,                  /* disconnect */
  ZERO_NULL,                        /* readwrite */
  PORT_IMAPS,                       /* defport */
  CURLPROTO_IMAP | CURLPROTO_IMAPS, /* protocol */
  PROTOPT_CLOSEACTION | PROTOPT_SSL | PROTOPT_NEEDSPWD
  | PROTOPT_NOURLQUERY              /* flags */
};
#endif

#ifndef CURL_DISABLE_HTTP
/*
 * HTTP-proxyed IMAP protocol handler.
 */

static const struct Curl_handler Curl_handler_imap_proxy = {
  "IMAP",                               /* scheme */
  Curl_http_setup_conn,                 /* setup_connection */
  Curl_http,                            /* do_it */
  Curl_http_done,                       /* done */
  ZERO_NULL,                            /* do_more */
  ZERO_NULL,                            /* connect_it */
  ZERO_NULL,                            /* connecting */
  ZERO_NULL,                            /* doing */
  ZERO_NULL,                            /* proto_getsock */
  ZERO_NULL,                            /* doing_getsock */
  ZERO_NULL,                            /* domore_getsock */
  ZERO_NULL,                            /* perform_getsock */
  ZERO_NULL,                            /* disconnect */
  ZERO_NULL,                            /* readwrite */
  PORT_IMAP,                            /* defport */
  CURLPROTO_HTTP,                       /* protocol */
  PROTOPT_NONE                          /* flags */
};

#ifdef USE_SSL
/*
 * HTTP-proxyed IMAPS protocol handler.
 */

static const struct Curl_handler Curl_handler_imaps_proxy = {
  "IMAPS",                              /* scheme */
  Curl_http_setup_conn,                 /* setup_connection */
  Curl_http,                            /* do_it */
  Curl_http_done,                       /* done */
  ZERO_NULL,                            /* do_more */
  ZERO_NULL,                            /* connect_it */
  ZERO_NULL,                            /* connecting */
  ZERO_NULL,                            /* doing */
  ZERO_NULL,                            /* proto_getsock */
  ZERO_NULL,                            /* doing_getsock */
  ZERO_NULL,                            /* domore_getsock */
  ZERO_NULL,                            /* perform_getsock */
  ZERO_NULL,                            /* disconnect */
  ZERO_NULL,                            /* readwrite */
  PORT_IMAPS,                           /* defport */
  CURLPROTO_HTTP,                       /* protocol */
  PROTOPT_NONE                          /* flags */
};
#endif
#endif

#ifdef USE_SSL
static void imap_to_imaps(struct connectdata *conn)
{
  conn->handler = &Curl_handler_imaps;
}
#else
#define imap_to_imaps(x) Curl_nop_stmt
#endif

/***********************************************************************
 *
 * imap_matchresp()
 *
 * Determines whether the untagged response is related to the specified
 * command by checking if it is in format "* <command-name> ..." or
 * "* <number> <command-name> ...".
 *
 * The "* " marker is assumed to have already been checked by the caller.
 */
static bool imap_matchresp(const char *line, size_t len, const char *cmd)
{
  const char *end = line + len;
  size_t cmd_len = strlen(cmd);

  /* Skip the untagged response marker */
  line += 2;

  /* Do we have a number after the marker? */
  if(line < end && ISDIGIT(*line)) {
    /* Skip the number */
    do
      line++;
    while(line < end && ISDIGIT(*line));

    /* Do we have the space character? */
    if(line == end || *line != ' ')
      return FALSE;

    line++;
  }

  /* Does the command name match and is it followed by a space character or at
     the end of line? */
  if(line + cmd_len <= end && Curl_raw_nequal(line, cmd, cmd_len) &&
     (line[cmd_len] == ' ' || line + cmd_len == end))
    return TRUE;

  return FALSE;
}

/***********************************************************************
 *
 * imap_endofresp()
 *
 * Checks whether the given string is a valid tagged, untagged or continuation
 * response which can be processed by the response handler.
 */
static bool imap_endofresp(struct connectdata *conn, char *line, size_t len,
                           int *resp)
{
  struct IMAP *imap = conn->data->req.protop;
  struct imap_conn *imapc = &conn->proto.imapc;
  const char *id = imapc->resptag;
  size_t id_len = strlen(id);

  /* Do we have a tagged command response? */
  if(len >= id_len + 1 && !memcmp(id, line, id_len) && line[id_len] == ' ') {
    line += id_len + 1;
    len -= id_len + 1;

    if(len >= 2 && !memcmp(line, "OK", 2))
      *resp = 'O';
    else if(len >= 2 && !memcmp(line, "NO", 2))
      *resp = 'N';
    else if(len >= 3 && !memcmp(line, "BAD", 3))
      *resp = 'B';
    else {
      failf(conn->data, "Bad tagged response");
      *resp = -1;
    }

    return TRUE;
  }

  /* Do we have an untagged command response? */
  if(len >= 2 && !memcmp("* ", line, 2)) {
    switch(imapc->state) {
      /* States which are interested in untagged responses */
      case IMAP_CAPABILITY:
        if(!imap_matchresp(line, len, "CAPABILITY"))
          return FALSE;
        break;

      case IMAP_LIST:
        if((!imap->custom && !imap_matchresp(line, len, "LIST")) ||
          (imap->custom && !imap_matchresp(line, len, imap->custom) &&
           (strcmp(imap->custom, "STORE") ||
            !imap_matchresp(line, len, "FETCH")) &&
           strcmp(imap->custom, "SELECT") &&
           strcmp(imap->custom, "EXAMINE") &&
           strcmp(imap->custom, "SEARCH") &&
           strcmp(imap->custom, "EXPUNGE") &&
           strcmp(imap->custom, "LSUB") &&
           strcmp(imap->custom, "UID") &&
           strcmp(imap->custom, "NOOP")))
          return FALSE;
        break;

      case IMAP_SELECT:
        /* SELECT is special in that its untagged responses do not have a
           common prefix so accept anything! */
        break;

      case IMAP_FETCH:
        if(!imap_matchresp(line, len, "FETCH"))
          return FALSE;
        break;

      /* Ignore other untagged responses */
      default:
        return FALSE;
    }

    *resp = '*';
    return TRUE;
  }

  /* Do we have a continuation response? This should be a + symbol followed by
     a space and optionally some text as per RFC-3501 for the AUTHENTICATE and
     APPEND commands and as outlined in Section 4. Examples of RFC-4959 but
     some e-mail servers ignore this and only send a single + instead. */
  if((len == 3 && !memcmp("+", line, 1)) ||
     (len >= 2 && !memcmp("+ ", line, 2))) {
    switch(imapc->state) {
      /* States which are interested in continuation responses */
      case IMAP_AUTHENTICATE_PLAIN:
      case IMAP_AUTHENTICATE_LOGIN:
      case IMAP_AUTHENTICATE_LOGIN_PASSWD:
      case IMAP_AUTHENTICATE_CRAMMD5:
      case IMAP_AUTHENTICATE_DIGESTMD5:
      case IMAP_AUTHENTICATE_DIGESTMD5_RESP:
      case IMAP_AUTHENTICATE_NTLM:
      case IMAP_AUTHENTICATE_NTLM_TYPE2MSG:
      case IMAP_AUTHENTICATE_XOAUTH2:
      case IMAP_AUTHENTICATE_FINAL:
      case IMAP_APPEND:
        *resp = '+';
        break;

      default:
        failf(conn->data, "Unexpected continuation response");
        *resp = -1;
        break;
    }

    return TRUE;
  }

  return FALSE; /* Nothing for us */
}

/***********************************************************************
 *
 * imap_get_message()
 *
 * Gets the authentication message from the response buffer.
 */
static void imap_get_message(char *buffer, char** outptr)
{
  size_t len = 0;
  char* message = NULL;

  /* Find the start of the message */
  for(message = buffer + 2; *message == ' ' || *message == '\t'; message++)
    ;

  /* Find the end of the message */
  for(len = strlen(message); len--;)
    if(message[len] != '\r' && message[len] != '\n' && message[len] != ' ' &&
        message[len] != '\t')
      break;

  /* Terminate the message */
  if(++len) {
    message[len] = '\0';
  }

  *outptr = message;
}

/***********************************************************************
 *
 * state()
 *
 * This is the ONLY way to change IMAP state!
 */
static void state(struct connectdata *conn, imapstate newstate)
{
  struct imap_conn *imapc = &conn->proto.imapc;
#if defined(DEBUGBUILD) && !defined(CURL_DISABLE_VERBOSE_STRINGS)
  /* for debug purposes */
  static const char * const names[]={
    "STOP",
    "SERVERGREET",
    "CAPABILITY",
    "STARTTLS",
    "UPGRADETLS",
    "AUTHENTICATE_PLAIN",
    "AUTHENTICATE_LOGIN",
    "AUTHENTICATE_LOGIN_PASSWD",
    "AUTHENTICATE_CRAMMD5",
    "AUTHENTICATE_DIGESTMD5",
    "AUTHENTICATE_DIGESTMD5_RESP",
    "AUTHENTICATE_NTLM",
    "AUTHENTICATE_NTLM_TYPE2MSG",
    "AUTHENTICATE_XOAUTH2",
    "AUTHENTICATE_CANCEL",
    "AUTHENTICATE_FINAL",
    "LOGIN",
    "LIST",
    "SELECT",
    "FETCH",
    "FETCH_FINAL",
    "APPEND",
    "APPEND_FINAL",
    "LOGOUT",
    /* LAST */
  };

  if(imapc->state != newstate)
    infof(conn->data, "IMAP %p state change from %s to %s\n",
          (void *)imapc, names[imapc->state], names[newstate]);
#endif

  imapc->state = newstate;
}

/***********************************************************************
 *
 * imap_perform_capability()
 *
 * Sends the CAPABILITY command in order to obtain a list of server side
 * supported capabilities.
 */
static CURLcode imap_perform_capability(struct connectdata *conn)
{
  CURLcode result = CURLE_OK;
  struct imap_conn *imapc = &conn->proto.imapc;

  imapc->authmechs = 0;         /* No known authentication mechanisms yet */
  imapc->authused = 0;          /* Clear the authentication mechanism used */
  imapc->tls_supported = FALSE; /* Clear the TLS capability */

  /* Send the CAPABILITY command */
  result = imap_sendf(conn, "CAPABILITY");

  if(!result)
    state(conn, IMAP_CAPABILITY);

  return result;
}

/***********************************************************************
 *
 * imap_perform_starttls()
 *
 * Sends the STARTTLS command to start the upgrade to TLS.
 */
static CURLcode imap_perform_starttls(struct connectdata *conn)
{
  CURLcode result = CURLE_OK;

  /* Send the STARTTLS command */
  result = imap_sendf(conn, "STARTTLS");

  if(!result)
    state(conn, IMAP_STARTTLS);

  return result;
}

/***********************************************************************
 *
 * imap_perform_upgrade_tls()
 *
 * Performs the upgrade to TLS.
 */
static CURLcode imap_perform_upgrade_tls(struct connectdata *conn)
{
  CURLcode result = CURLE_OK;
  struct imap_conn *imapc = &conn->proto.imapc;

  /* Start the SSL connection */
  result = Curl_ssl_connect_nonblocking(conn, FIRSTSOCKET, &imapc->ssldone);

  if(!result) {
    if(imapc->state != IMAP_UPGRADETLS)
      state(conn, IMAP_UPGRADETLS);

    if(imapc->ssldone) {
      imap_to_imaps(conn);
      result = imap_perform_capability(conn);
    }
  }

  return result;
}

/***********************************************************************
 *
 * imap_perform_login()
 *
 * Sends a clear text LOGIN command to authenticate with.
 */
static CURLcode imap_perform_login(struct connectdata *conn)
{
  CURLcode result = CURLE_OK;
  char *user;
  char *passwd;

  /* Check we have a username and password to authenticate with and end the
     connect phase if we don't */
  if(!conn->bits.user_passwd) {
    state(conn, IMAP_STOP);

    return result;
  }

  /* Make sure the username and password are in the correct atom format */
  user = imap_atom(conn->user);
  passwd = imap_atom(conn->passwd);

  /* Send the LOGIN command */
  result = imap_sendf(conn, "LOGIN %s %s", user ? user : "",
                      passwd ? passwd : "");

  Curl_safefree(user);
  Curl_safefree(passwd);

  if(!result)
    state(conn, IMAP_LOGIN);

  return result;
}

/***********************************************************************
 *
 * imap_perform_authenticate()
 *
 * Sends an AUTHENTICATE command allowing the client to login with the
 * appropriate SASL authentication mechanism.
 *
 * Additionally, the function will perform fallback to the LOGIN command
 * should a common mechanism not be available between the client and server.
 */
static CURLcode imap_perform_authenticate(struct connectdata *conn)
{
  CURLcode result = CURLE_OK;
  struct SessionHandle *data = conn->data;
  struct imap_conn *imapc = &conn->proto.imapc;
  const char *mech = NULL;
  char *initresp = NULL;
  size_t len = 0;
  imapstate state1 = IMAP_STOP;
  imapstate state2 = IMAP_STOP;

  /* Check we have a username and password to authenticate with and end the
     connect phase if we don't */
  if(!conn->bits.user_passwd) {
    state(conn, IMAP_STOP);

    return result;
  }

  /* Calculate the supported authentication mechanism, by decreasing order of
     security, as well as the initial response where appropriate */
#ifndef CURL_DISABLE_CRYPTO_AUTH
  if((imapc->authmechs & SASL_MECH_DIGEST_MD5) &&
     (imapc->prefmech & SASL_MECH_DIGEST_MD5)) {
    mech = SASL_MECH_STRING_DIGEST_MD5;
    state1 = IMAP_AUTHENTICATE_DIGESTMD5;
    imapc->authused = SASL_MECH_DIGEST_MD5;
  }
  else if((imapc->authmechs & SASL_MECH_CRAM_MD5) &&
          (imapc->prefmech & SASL_MECH_CRAM_MD5)) {
    mech = SASL_MECH_STRING_CRAM_MD5;
    state1 = IMAP_AUTHENTICATE_CRAMMD5;
    imapc->authused = SASL_MECH_CRAM_MD5;
  }
  else
#endif
#ifdef USE_NTLM
    if((imapc->authmechs & SASL_MECH_NTLM) &&
       (imapc->prefmech & SASL_MECH_NTLM)) {
    mech = SASL_MECH_STRING_NTLM;
    state1 = IMAP_AUTHENTICATE_NTLM;
    state2 = IMAP_AUTHENTICATE_NTLM_TYPE2MSG;
    imapc->authused = SASL_MECH_NTLM;

    if(imapc->ir_supported || data->set.sasl_ir)
      result = Curl_sasl_create_ntlm_type1_message(conn->user, conn->passwd,
                                                   &conn->ntlm,
                                                   &initresp, &len);
  }
  else
#endif
  if(((imapc->authmechs & SASL_MECH_XOAUTH2) &&
      (imapc->prefmech & SASL_MECH_XOAUTH2) &&
      (imapc->prefmech != SASL_AUTH_ANY)) || conn->xoauth2_bearer) {
    mech = SASL_MECH_STRING_XOAUTH2;
    state1 = IMAP_AUTHENTICATE_XOAUTH2;
    state2 = IMAP_AUTHENTICATE_FINAL;
    imapc->authused = SASL_MECH_XOAUTH2;

    if(imapc->ir_supported || data->set.sasl_ir)
      result = Curl_sasl_create_xoauth2_message(conn->data, conn->user,
                                                conn->xoauth2_bearer,
                                                &initresp, &len);
  }
  else if((imapc->authmechs & SASL_MECH_LOGIN) &&
     (imapc->prefmech & SASL_MECH_LOGIN)) {
    mech = SASL_MECH_STRING_LOGIN;
    state1 = IMAP_AUTHENTICATE_LOGIN;
    state2 = IMAP_AUTHENTICATE_LOGIN_PASSWD;
    imapc->authused = SASL_MECH_LOGIN;

    if(imapc->ir_supported || data->set.sasl_ir)
      result = Curl_sasl_create_login_message(conn->data, conn->user,
                                              &initresp, &len);
  }
  else if((imapc->authmechs & SASL_MECH_PLAIN) &&
          (imapc->prefmech & SASL_MECH_PLAIN)) {
    mech = SASL_MECH_STRING_PLAIN;
    state1 = IMAP_AUTHENTICATE_PLAIN;
    state2 = IMAP_AUTHENTICATE_FINAL;
    imapc->authused = SASL_MECH_PLAIN;

    if(imapc->ir_supported || data->set.sasl_ir)
      result = Curl_sasl_create_plain_message(conn->data, conn->user,
                                              conn->passwd, &initresp, &len);
  }

  if(!result) {
    if(mech && (imapc->preftype & IMAP_TYPE_SASL)) {
      /* Perform SASL based authentication */
      if(initresp) {
        result = imap_sendf(conn, "AUTHENTICATE %s %s", mech, initresp);

        if(!result)
          state(conn, state2);
      }
      else {
        result = imap_sendf(conn, "AUTHENTICATE %s", mech);

        if(!result)
          state(conn, state1);
      }

      Curl_safefree(initresp);
    }
    else if((!imapc->login_disabled) &&
            (imapc->preftype & IMAP_TYPE_CLEARTEXT))
      /* Perform clear text authentication */
      result = imap_perform_login(conn);
    else {
      /* Other mechanisms not supported */
      infof(conn->data, "No known authentication mechanisms supported!\n");
      result = CURLE_LOGIN_DENIED;
    }
  }

  return result;
}

/***********************************************************************
 *
 * imap_perform_list()
 *
 * Sends a LIST command or an alternative custom request.
 */
static CURLcode imap_perform_list(struct connectdata *conn)
{
  CURLcode result = CURLE_OK;
  struct SessionHandle *data = conn->data;
  struct IMAP *imap = data->req.protop;
  char *mailbox;

  if(imap->custom)
    /* Send the custom request */
    result = imap_sendf(conn, "%s%s", imap->custom,
                        imap->custom_params ? imap->custom_params : "");
  else {
    /* Make sure the mailbox is in the correct atom format */
    mailbox = imap_atom(imap->mailbox ? imap->mailbox : "");
    if(!mailbox)
      return CURLE_OUT_OF_MEMORY;

    /* Send the LIST command */
    result = imap_sendf(conn, "LIST \"%s\" *", mailbox);

    Curl_safefree(mailbox);
  }

  if(!result)
    state(conn, IMAP_LIST);

  return result;
}

/***********************************************************************
 *
 * imap_perform_select()
 *
 * Sends a SELECT command to ask the server to change the selected mailbox.
 */
static CURLcode imap_perform_select(struct connectdata *conn)
{
  CURLcode result = CURLE_OK;
  struct SessionHandle *data = conn->data;
  struct IMAP *imap = data->req.protop;
  struct imap_conn *imapc = &conn->proto.imapc;
  char *mailbox;

  /* Invalidate old information as we are switching mailboxes */
  Curl_safefree(imapc->mailbox);
  Curl_safefree(imapc->mailbox_uidvalidity);

  /* Check we have a mailbox */
  if(!imap->mailbox) {
    failf(conn->data, "Cannot SELECT without a mailbox.");
    return CURLE_URL_MALFORMAT;
  }

  /* Make sure the mailbox is in the correct atom format */
  mailbox = imap_atom(imap->mailbox);
  if(!mailbox)
    return CURLE_OUT_OF_MEMORY;

  /* Send the SELECT command */
  result = imap_sendf(conn, "SELECT %s", mailbox);

  Curl_safefree(mailbox);

  if(!result)
    state(conn, IMAP_SELECT);

  return result;
}

/***********************************************************************
 *
 * imap_perform_fetch()
 *
 * Sends a FETCH command to initiate the download of a message.
 */
static CURLcode imap_perform_fetch(struct connectdata *conn)
{
  CURLcode result = CURLE_OK;
  struct IMAP *imap = conn->data->req.protop;

  /* Check we have a UID */
  if(!imap->uid) {
    failf(conn->data, "Cannot FETCH without a UID.");
    return CURLE_URL_MALFORMAT;
  }

  /* Send the FETCH command */
  result = imap_sendf(conn, "FETCH %s BODY[%s]",
                      imap->uid,
                      imap->section ? imap->section : "");

  if(!result)
    state(conn, IMAP_FETCH);

  return result;
}

/***********************************************************************
 *
 * imap_perform_append()
 *
 * Sends an APPEND command to initiate the upload of a message.
 */
static CURLcode imap_perform_append(struct connectdata *conn)
{
  CURLcode result = CURLE_OK;
  struct IMAP *imap = conn->data->req.protop;
  char *mailbox;

  /* Check we have a mailbox */
  if(!imap->mailbox) {
    failf(conn->data, "Cannot APPEND without a mailbox.");
    return CURLE_URL_MALFORMAT;
  }

  /* Check we know the size of the upload */
  if(conn->data->set.infilesize < 0) {
    failf(conn->data, "Cannot APPEND with unknown input file size\n");
    return CURLE_UPLOAD_FAILED;
  }

  /* Make sure the mailbox is in the correct atom format */
  mailbox = imap_atom(imap->mailbox);
  if(!mailbox)
    return CURLE_OUT_OF_MEMORY;

  /* Send the APPEND command */
  result = imap_sendf(conn, "APPEND %s (\\Seen) {%" FORMAT_OFF_T "}",
                      mailbox, conn->data->set.infilesize);

  Curl_safefree(mailbox);

  if(!result)
    state(conn, IMAP_APPEND);

  return result;
}

/***********************************************************************
 *
 * imap_perform_logout()
 *
 * Performs the logout action prior to sclose() being called.
 */
static CURLcode imap_perform_logout(struct connectdata *conn)
{
  CURLcode result = CURLE_OK;

  /* Send the LOGOUT command */
  result = imap_sendf(conn, "LOGOUT");

  if(!result)
    state(conn, IMAP_LOGOUT);

  return result;
}

/* For the initial server greeting */
static CURLcode imap_state_servergreet_resp(struct connectdata *conn,
                                            int imapcode,
                                            imapstate instate)
{
  CURLcode result = CURLE_OK;
  struct SessionHandle *data = conn->data;

  (void)instate; /* no use for this yet */

  if(imapcode != 'O') {
    failf(data, "Got unexpected imap-server response");
    result = CURLE_FTP_WEIRD_SERVER_REPLY; /* TODO: fix this code */
  }
  else
    result = imap_perform_capability(conn);

  return result;
}

/* For CAPABILITY responses */
static CURLcode imap_state_capability_resp(struct connectdata *conn,
                                           int imapcode,
                                           imapstate instate)
{
  CURLcode result = CURLE_OK;
  struct SessionHandle *data = conn->data;
  struct imap_conn *imapc = &conn->proto.imapc;
  const char *line = data->state.buffer;
  size_t wordlen;

  (void)instate; /* no use for this yet */

  /* Do we have a untagged response? */
  if(imapcode == '*') {
    line += 2;

    /* Loop through the data line */
    for(;;) {
      while(*line &&
            (*line == ' ' || *line == '\t' ||
              *line == '\r' || *line == '\n')) {

        line++;
      }

      if(!*line)
        break;

      /* Extract the word */
      for(wordlen = 0; line[wordlen] && line[wordlen] != ' ' &&
            line[wordlen] != '\t' && line[wordlen] != '\r' &&
            line[wordlen] != '\n';)
        wordlen++;

      /* Does the server support the STARTTLS capability? */
      if(wordlen == 8 && !memcmp(line, "STARTTLS", 8))
        imapc->tls_supported = TRUE;

      /* Has the server explicitly disabled clear text authentication? */
      else if(wordlen == 13 && !memcmp(line, "LOGINDISABLED", 13))
        imapc->login_disabled = TRUE;

      /* Does the server support the SASL-IR capability? */
      else if(wordlen == 7 && !memcmp(line, "SASL-IR", 7))
        imapc->ir_supported = TRUE;

      /* Do we have a SASL based authentication mechanism? */
      else if(wordlen > 5 && !memcmp(line, "AUTH=", 5)) {
        line += 5;
        wordlen -= 5;

        /* Test the word for a matching authentication mechanism */
        if(sasl_mech_equal(line, wordlen, SASL_MECH_STRING_LOGIN))
          imapc->authmechs |= SASL_MECH_LOGIN;
        else if(sasl_mech_equal(line, wordlen, SASL_MECH_STRING_PLAIN))
          imapc->authmechs |= SASL_MECH_PLAIN;
        else if(sasl_mech_equal(line, wordlen, SASL_MECH_STRING_CRAM_MD5))
          imapc->authmechs |= SASL_MECH_CRAM_MD5;
        else if(sasl_mech_equal(line, wordlen, SASL_MECH_STRING_DIGEST_MD5))
          imapc->authmechs |= SASL_MECH_DIGEST_MD5;
        else if(sasl_mech_equal(line, wordlen, SASL_MECH_STRING_GSSAPI))
          imapc->authmechs |= SASL_MECH_GSSAPI;
        else if(sasl_mech_equal(line, wordlen, SASL_MECH_STRING_EXTERNAL))
          imapc->authmechs |= SASL_MECH_EXTERNAL;
        else if(sasl_mech_equal(line, wordlen, SASL_MECH_STRING_NTLM))
          imapc->authmechs |= SASL_MECH_NTLM;
        else if(sasl_mech_equal(line, wordlen, SASL_MECH_STRING_XOAUTH2))
          imapc->authmechs |= SASL_MECH_XOAUTH2;
      }

      line += wordlen;
    }
  }
  else if(imapcode == 'O') {
    if(data->set.use_ssl && !conn->ssl[FIRSTSOCKET].use) {
      /* We don't have a SSL/TLS connection yet, but SSL is requested */
      if(imapc->tls_supported)
        /* Switch to TLS connection now */
        result = imap_perform_starttls(conn);
      else if(data->set.use_ssl == CURLUSESSL_TRY)
        /* Fallback and carry on with authentication */
        result = imap_perform_authenticate(conn);
      else {
        failf(data, "STARTTLS not supported.");
        result = CURLE_USE_SSL_FAILED;
      }
    }
    else
      result = imap_perform_authenticate(conn);
  }
  else
    result = imap_perform_login(conn);

  return result;
}

/* For STARTTLS responses */
static CURLcode imap_state_starttls_resp(struct connectdata *conn,
                                         int imapcode,
                                         imapstate instate)
{
  CURLcode result = CURLE_OK;
  struct SessionHandle *data = conn->data;

  (void)instate; /* no use for this yet */

  if(imapcode != 'O') {
    if(data->set.use_ssl != CURLUSESSL_TRY) {
      failf(data, "STARTTLS denied. %c", imapcode);
      result = CURLE_USE_SSL_FAILED;
    }
    else
      result = imap_perform_authenticate(conn);
  }
  else
    result = imap_perform_upgrade_tls(conn);

  return result;
}

/* For AUTHENTICATE PLAIN (without initial response) responses */
static CURLcode imap_state_auth_plain_resp(struct connectdata *conn,
                                           int imapcode,
                                           imapstate instate)
{
  CURLcode result = CURLE_OK;
  struct SessionHandle *data = conn->data;
  size_t len = 0;
  char *plainauth = NULL;

  (void)instate; /* no use for this yet */

  if(imapcode != '+') {
    failf(data, "Access denied. %c", imapcode);
    result = CURLE_LOGIN_DENIED;
  }
  else {
    /* Create the authorisation message */
    result = Curl_sasl_create_plain_message(data, conn->user, conn->passwd,
                                            &plainauth, &len);
    if(!result && plainauth) {
      /* Send the message */
      result = Curl_pp_sendf(&conn->proto.imapc.pp, "%s", plainauth);

      if(!result)
        state(conn, IMAP_AUTHENTICATE_FINAL);
    }
  }

  Curl_safefree(plainauth);

  return result;
}

/* For AUTHENTICATE LOGIN (without initial response) responses */
static CURLcode imap_state_auth_login_resp(struct connectdata *conn,
                                           int imapcode,
                                           imapstate instate)
{
  CURLcode result = CURLE_OK;
  struct SessionHandle *data = conn->data;
  size_t len = 0;
  char *authuser = NULL;

  (void)instate; /* no use for this yet */

  if(imapcode != '+') {
    failf(data, "Access denied: %d", imapcode);
    result = CURLE_LOGIN_DENIED;
  }
  else {
    /* Create the user message */
    result = Curl_sasl_create_login_message(data, conn->user,
                                            &authuser, &len);
    if(!result && authuser) {
      /* Send the user */
      result = Curl_pp_sendf(&conn->proto.imapc.pp, "%s", authuser);

      if(!result)
        state(conn, IMAP_AUTHENTICATE_LOGIN_PASSWD);
    }
  }

  Curl_safefree(authuser);

  return result;
}

/* For AUTHENTICATE LOGIN user entry responses */
static CURLcode imap_state_auth_login_password_resp(struct connectdata *conn,
                                                    int imapcode,
                                                    imapstate instate)
{
  CURLcode result = CURLE_OK;
  struct SessionHandle *data = conn->data;
  size_t len = 0;
  char *authpasswd = NULL;

  (void)instate; /* no use for this yet */

  if(imapcode != '+') {
    failf(data, "Access denied: %d", imapcode);
    result = CURLE_LOGIN_DENIED;
  }
  else {
    /* Create the password message */
    result = Curl_sasl_create_login_message(data, conn->passwd,
                                            &authpasswd, &len);
    if(!result && authpasswd) {
      /* Send the password */
      result = Curl_pp_sendf(&conn->proto.imapc.pp, "%s", authpasswd);

      if(!result)
        state(conn, IMAP_AUTHENTICATE_FINAL);
    }
  }

  Curl_safefree(authpasswd);

  return result;
}

#ifndef CURL_DISABLE_CRYPTO_AUTH
/* For AUTHENTICATE CRAM-MD5 responses */
static CURLcode imap_state_auth_cram_resp(struct connectdata *conn,
                                          int imapcode,
                                          imapstate instate)
{
  CURLcode result = CURLE_OK;
  struct SessionHandle *data = conn->data;
  char *chlg = NULL;
  char *chlg64 = NULL;
  char *rplyb64 = NULL;
  size_t len = 0;

  (void)instate; /* no use for this yet */

  if(imapcode != '+') {
    failf(data, "Access denied: %d", imapcode);
    return CURLE_LOGIN_DENIED;
  }

  /* Get the challenge message */
  imap_get_message(data->state.buffer, &chlg64);

  /* Decode the challenge message */
  result = Curl_sasl_decode_cram_md5_message(chlg64, &chlg, &len);
  if(result) {
    /* Send the cancellation */
    result = Curl_pp_sendf(&conn->proto.imapc.pp, "%s", "*");

    if(!result)
      state(conn, IMAP_AUTHENTICATE_CANCEL);
  }
  else {
    /* Create the response message */
    result = Curl_sasl_create_cram_md5_message(data, chlg, conn->user,
                                               conn->passwd, &rplyb64, &len);
    if(!result && rplyb64) {
      /* Send the response */
      result = Curl_pp_sendf(&conn->proto.imapc.pp, "%s", rplyb64);

      if(!result)
        state(conn, IMAP_AUTHENTICATE_FINAL);
    }
  }

  Curl_safefree(chlg);
  Curl_safefree(rplyb64);

  return result;
}

/* For AUTHENTICATE DIGEST-MD5 challenge responses */
static CURLcode imap_state_auth_digest_resp(struct connectdata *conn,
                                            int imapcode,
                                            imapstate instate)
{
  CURLcode result = CURLE_OK;
  struct SessionHandle *data = conn->data;
  char *chlg64 = NULL;
  char *rplyb64 = NULL;
  size_t len = 0;

  char nonce[64];
  char realm[128];
  char algorithm[64];

  (void)instate; /* no use for this yet */

  if(imapcode != '+') {
    failf(data, "Access denied: %d", imapcode);
    return CURLE_LOGIN_DENIED;
  }

  /* Get the challenge message */
  imap_get_message(data->state.buffer, &chlg64);

  /* Decode the challange message */
  result = Curl_sasl_decode_digest_md5_message(chlg64, nonce, sizeof(nonce),
                                               realm, sizeof(realm),
                                               algorithm, sizeof(algorithm));
  if(result || strcmp(algorithm, "md5-sess") != 0) {
    /* Send the cancellation */
    result = Curl_pp_sendf(&conn->proto.imapc.pp, "%s", "*");

    if(!result)
      state(conn, IMAP_AUTHENTICATE_CANCEL);
  }
  else {
    /* Create the response message */
    result = Curl_sasl_create_digest_md5_message(data, nonce, realm,
                                                 conn->user, conn->passwd,
                                                 "imap", &rplyb64, &len);
    if(!result && rplyb64) {
      /* Send the response */
      result = Curl_pp_sendf(&conn->proto.imapc.pp, "%s", rplyb64);

      if(!result)
        state(conn, IMAP_AUTHENTICATE_DIGESTMD5_RESP);
    }
  }

  Curl_safefree(rplyb64);

  return result;
}

/* For AUTHENTICATE DIGEST-MD5 challenge-response responses */
static CURLcode imap_state_auth_digest_resp_resp(struct connectdata *conn,
                                                 int imapcode,
                                                 imapstate instate)
{
  CURLcode result = CURLE_OK;
  struct SessionHandle *data = conn->data;

  (void)instate; /* no use for this yet */

  if(imapcode != '+') {
    failf(data, "Authentication failed: %d", imapcode);
    result = CURLE_LOGIN_DENIED;
  }
  else {
    /* Send an empty response */
    result = Curl_pp_sendf(&conn->proto.imapc.pp, "%s", "");

    if(!result)
      state(conn, IMAP_AUTHENTICATE_FINAL);
  }

  return result;
}
#endif

#ifdef USE_NTLM
/* For AUTHENTICATE NTLM (without initial response) responses */
static CURLcode imap_state_auth_ntlm_resp(struct connectdata *conn,
                                          int imapcode,
                                          imapstate instate)
{
  CURLcode result = CURLE_OK;
  struct SessionHandle *data = conn->data;
  size_t len = 0;
  char *type1msg = NULL;

  (void)instate; /* no use for this yet */

  if(imapcode != '+') {
    failf(data, "Access denied: %d", imapcode);
    result = CURLE_LOGIN_DENIED;
  }
  else {
    /* Create the type-1 message */
    result = Curl_sasl_create_ntlm_type1_message(conn->user, conn->passwd,
                                                 &conn->ntlm,
                                                 &type1msg, &len);
    if(!result && type1msg) {
      /* Send the message */
      result = Curl_pp_sendf(&conn->proto.imapc.pp, "%s", type1msg);

      if(!result)
        state(conn, IMAP_AUTHENTICATE_NTLM_TYPE2MSG);
    }
  }

  Curl_safefree(type1msg);

  return result;
}

/* For NTLM type-2 responses (sent in reponse to our type-1 message) */
static CURLcode imap_state_auth_ntlm_type2msg_resp(struct connectdata *conn,
                                                   int imapcode,
                                                   imapstate instate)
{
  CURLcode result = CURLE_OK;
  struct SessionHandle *data = conn->data;
  char *type2msg = NULL;
  char *type3msg = NULL;
  size_t len = 0;

  (void)instate; /* no use for this yet */

  if(imapcode != '+') {
    failf(data, "Access denied: %d", imapcode);
    result = CURLE_LOGIN_DENIED;
  }
  else {
    /* Get the challenge message */
    imap_get_message(data->state.buffer, &type2msg);

    /* Decode the type-2 message */
    result = Curl_sasl_decode_ntlm_type2_message(data, type2msg, &conn->ntlm);
    if(result) {
      /* Send the cancellation */
      result = Curl_pp_sendf(&conn->proto.imapc.pp, "%s", "*");

      if(!result)
        state(conn, IMAP_AUTHENTICATE_CANCEL);
    }
    else {
      /* Create the type-3 message */
      result = Curl_sasl_create_ntlm_type3_message(data, conn->user,
                                                   conn->passwd, &conn->ntlm,
                                                   &type3msg, &len);
      if(!result && type3msg) {
        /* Send the message */
        result = Curl_pp_sendf(&conn->proto.imapc.pp, "%s", type3msg);

        if(!result)
          state(conn, IMAP_AUTHENTICATE_FINAL);
      }
    }
  }

  Curl_safefree(type3msg);

  return result;
}
#endif

/* For AUTHENTICATE XOAUTH2 (without initial response) responses */
static CURLcode imap_state_auth_xoauth2_resp(struct connectdata *conn,
                                             int imapcode,
                                             imapstate instate)
{
  CURLcode result = CURLE_OK;
  struct SessionHandle *data = conn->data;
  size_t len = 0;
  char *xoauth = NULL;

  (void)instate; /* no use for this yet */

  if(imapcode != '+') {
    failf(data, "Access denied: %d", imapcode);
    result = CURLE_LOGIN_DENIED;
  }
  else {
    /* Create the authorisation message */
    result = Curl_sasl_create_xoauth2_message(conn->data, conn->user,
                                              conn->xoauth2_bearer,
                                              &xoauth, &len);
    if(!result && xoauth) {
      /* Send the message */
      result = Curl_pp_sendf(&conn->proto.imapc.pp, "%s", xoauth);

      if(!result)
        state(conn, IMAP_AUTHENTICATE_FINAL);
    }
  }

  Curl_safefree(xoauth);

  return result;
}

/* For AUTHENTICATE cancellation responses */
static CURLcode imap_state_auth_cancel_resp(struct connectdata *conn,
                                            int imapcode,
                                            imapstate instate)
{
  struct SessionHandle *data = conn->data;

  (void)imapcode;
  (void)instate; /* no use for this yet */

  failf(data, "Authentication cancelled");

  return CURLE_LOGIN_DENIED;
}

/* For final responses in the AUTHENTICATE sequence */
static CURLcode imap_state_auth_final_resp(struct connectdata *conn,
                                           int imapcode,
                                           imapstate instate)
{
  CURLcode result = CURLE_OK;
  struct SessionHandle *data = conn->data;

  (void)instate; /* no use for this yet */

  if(imapcode != 'O') {
    failf(data, "Authentication failed: %d", imapcode);
    result = CURLE_LOGIN_DENIED;
  }
  else
    /* End of connect phase */
    state(conn, IMAP_STOP);

  return result;
}

/* For LOGIN responses */
static CURLcode imap_state_login_resp(struct connectdata *conn,
                                      int imapcode,
                                      imapstate instate)
{
  CURLcode result = CURLE_OK;
  struct SessionHandle *data = conn->data;

  (void)instate; /* no use for this yet */

  if(imapcode != 'O') {
    failf(data, "Access denied. %c", imapcode);
    result = CURLE_LOGIN_DENIED;
  }
  else
    /* End of connect phase */
    state(conn, IMAP_STOP);

  return result;
}

/* For LIST responses */
static CURLcode imap_state_list_resp(struct connectdata *conn, int imapcode,
                                     imapstate instate)
{
  CURLcode result = CURLE_OK;
  char *line = conn->data->state.buffer;
  size_t len = strlen(line);

  (void)instate; /* No use for this yet */

  if(imapcode == '*') {
    /* Temporarily add the LF character back and send as body to the client */
    line[len] = '\n';
    result = Curl_client_write(conn, CLIENTWRITE_BODY, line, len + 1);
    line[len] = '\0';
  }
  else if(imapcode != 'O')
    result = CURLE_QUOTE_ERROR; /* TODO: Fix error code */
  else
    /* End of DO phase */
    state(conn, IMAP_STOP);

  return result;
}

/* For SELECT responses */
static CURLcode imap_state_select_resp(struct connectdata *conn, int imapcode,
                                       imapstate instate)
{
  CURLcode result = CURLE_OK;
  struct SessionHandle *data = conn->data;
  struct IMAP *imap = conn->data->req.protop;
  struct imap_conn *imapc = &conn->proto.imapc;
  const char *line = data->state.buffer;
  char tmp[20];

  (void)instate; /* no use for this yet */

  if(imapcode == '*') {
    /* See if this is an UIDVALIDITY response */
    if(sscanf(line + 2, "OK [UIDVALIDITY %19[0123456789]]", tmp) == 1) {
      Curl_safefree(imapc->mailbox_uidvalidity);
      imapc->mailbox_uidvalidity = strdup(tmp);
    }
  }
  else if(imapcode == 'O') {
    /* Check if the UIDVALIDITY has been specified and matches */
    if(imap->uidvalidity && imapc->mailbox_uidvalidity &&
       strcmp(imap->uidvalidity, imapc->mailbox_uidvalidity)) {
      failf(conn->data, "Mailbox UIDVALIDITY has changed");
      result = CURLE_REMOTE_FILE_NOT_FOUND;
    }
    else {
      /* Note the currently opened mailbox on this connection */
      imapc->mailbox = strdup(imap->mailbox);

      if(imap->custom)
        result = imap_perform_list(conn);
      else
        result = imap_perform_fetch(conn);
    }
  }
  else {
    failf(data, "Select failed");
    result = CURLE_LOGIN_DENIED;
  }

  return result;
}

/* For the (first line of the) FETCH responses */
static CURLcode imap_state_fetch_resp(struct connectdata *conn, int imapcode,
                                      imapstate instate)
{
  CURLcode result = CURLE_OK;
  struct SessionHandle *data = conn->data;
  struct imap_conn *imapc = &conn->proto.imapc;
  struct pingpong *pp = &imapc->pp;
  const char *ptr = data->state.buffer;
  bool parsed = FALSE;
  curl_off_t size;

  (void)instate; /* no use for this yet */

  if(imapcode != '*') {
    Curl_pgrsSetDownloadSize(data, 0);
    state(conn, IMAP_STOP);
    return CURLE_REMOTE_FILE_NOT_FOUND; /* TODO: Fix error code */
  }

  /* Something like this is received "* 1 FETCH (BODY[TEXT] {2021}\r" so parse
     the continuation data contained within the curly brackets */
  while(*ptr && (*ptr != '{'))
    ptr++;

  if(*ptr == '{') {
    char *endptr;
    size = curlx_strtoofft(ptr + 1, &endptr, 10);
    if(endptr - ptr > 1 && endptr[0] == '}' &&
       endptr[1] == '\r' && endptr[2] == '\0')
      parsed = TRUE;
  }

  if(parsed) {
    infof(data, "Found %" FORMAT_OFF_TU " bytes to download\n", size);
    Curl_pgrsSetDownloadSize(data, size);

    if(pp->cache) {
      /* At this point there is a bunch of data in the header "cache" that is
         actually body content, send it as body and then skip it. Do note
         that there may even be additional "headers" after the body. */
      size_t chunk = pp->cache_size;

      if(chunk > (size_t)size)
        /* The conversion from curl_off_t to size_t is always fine here */
        chunk = (size_t)size;

      result = Curl_client_write(conn, CLIENTWRITE_BODY, pp->cache, chunk);
      if(result)
        return result;

      data->req.bytecount += chunk;

      infof(data, "Written %" FORMAT_OFF_TU " bytes, %" FORMAT_OFF_TU
            " bytes are left for transfer\n", (curl_off_t)chunk,
            size - chunk);

      /* Have we used the entire cache or just part of it?*/
      if(pp->cache_size > chunk) {
        /* Only part of it so shrink the cache to fit the trailing data */
        memmove(pp->cache, pp->cache + chunk, pp->cache_size - chunk);
        pp->cache_size -= chunk;
      }
      else {
        /* Free the cache */
        Curl_safefree(pp->cache);

        /* Reset the cache size */
        pp->cache_size = 0;
      }
    }

    if(data->req.bytecount == size)
      /* The entire data is already transferred! */
      Curl_setup_transfer(conn, -1, -1, FALSE, NULL, -1, NULL);
    else {
      /* IMAP download */
      data->req.maxdownload = size;
      Curl_setup_transfer(conn, FIRSTSOCKET, size, FALSE, NULL, -1, NULL);
    }
  }
  else {
    /* We don't know how to parse this line */
    failf(pp->conn->data, "Failed to parse FETCH response.");
    result = CURLE_FTP_WEIRD_SERVER_REPLY; /* TODO: fix this code */
  }

  /* End of DO phase */
  state(conn, IMAP_STOP);

  return result;
}

/* For final FETCH responses performed after the download */
static CURLcode imap_state_fetch_final_resp(struct connectdata *conn,
                                            int imapcode,
                                            imapstate instate)
{
  CURLcode result = CURLE_OK;

  (void)instate; /* No use for this yet */

  if(imapcode != 'O')
    result = CURLE_FTP_WEIRD_SERVER_REPLY; /* TODO: Fix error code */
  else
    /* End of DONE phase */
    state(conn, IMAP_STOP);

  return result;
}

/* For APPEND responses */
static CURLcode imap_state_append_resp(struct connectdata *conn, int imapcode,
                                       imapstate instate)
{
  CURLcode result = CURLE_OK;
  struct SessionHandle *data = conn->data;

  (void)instate; /* No use for this yet */

  if(imapcode != '+') {
    result = CURLE_UPLOAD_FAILED;
  }
  else {
    /* Set the progress upload size */
    Curl_pgrsSetUploadSize(data, data->set.infilesize);

    /* IMAP upload */
    Curl_setup_transfer(conn, -1, -1, FALSE, NULL, FIRSTSOCKET, NULL);

    /* End of DO phase */
    state(conn, IMAP_STOP);
  }

  return result;
}

/* For final APPEND responses performed after the upload */
static CURLcode imap_state_append_final_resp(struct connectdata *conn,
                                             int imapcode,
                                             imapstate instate)
{
  CURLcode result = CURLE_OK;

  (void)instate; /* No use for this yet */

  if(imapcode != 'O')
    result = CURLE_UPLOAD_FAILED;
  else
    /* End of DONE phase */
    state(conn, IMAP_STOP);

  return result;
}

static CURLcode imap_statemach_act(struct connectdata *conn)
{
  CURLcode result = CURLE_OK;
  curl_socket_t sock = conn->sock[FIRSTSOCKET];
  int imapcode;
  struct imap_conn *imapc = &conn->proto.imapc;
  struct pingpong *pp = &imapc->pp;
  size_t nread = 0;

  /* Busy upgrading the connection; right now all I/O is SSL/TLS, not IMAP */
  if(imapc->state == IMAP_UPGRADETLS)
    return imap_perform_upgrade_tls(conn);

  /* Flush any data that needs to be sent */
  if(pp->sendleft)
    return Curl_pp_flushsend(pp);

  do {
    /* Read the response from the server */
    result = Curl_pp_readresp(sock, pp, &imapcode, &nread);
    if(result)
      return result;

    /* Was there an error parsing the response line? */
    if(imapcode == -1)
      return CURLE_FTP_WEIRD_SERVER_REPLY;

    if(!imapcode)
      break;

    /* We have now received a full IMAP server response */
    switch(imapc->state) {
    case IMAP_SERVERGREET:
      result = imap_state_servergreet_resp(conn, imapcode, imapc->state);
      break;

    case IMAP_CAPABILITY:
      result = imap_state_capability_resp(conn, imapcode, imapc->state);
      break;

    case IMAP_STARTTLS:
      result = imap_state_starttls_resp(conn, imapcode, imapc->state);
      break;

    case IMAP_AUTHENTICATE_PLAIN:
      result = imap_state_auth_plain_resp(conn, imapcode, imapc->state);
      break;

    case IMAP_AUTHENTICATE_LOGIN:
      result = imap_state_auth_login_resp(conn, imapcode, imapc->state);
      break;

    case IMAP_AUTHENTICATE_LOGIN_PASSWD:
      result = imap_state_auth_login_password_resp(conn, imapcode,
                                                   imapc->state);
      break;

#ifndef CURL_DISABLE_CRYPTO_AUTH
    case IMAP_AUTHENTICATE_CRAMMD5:
      result = imap_state_auth_cram_resp(conn, imapcode, imapc->state);
      break;

    case IMAP_AUTHENTICATE_DIGESTMD5:
      result = imap_state_auth_digest_resp(conn, imapcode, imapc->state);
      break;

    case IMAP_AUTHENTICATE_DIGESTMD5_RESP:
      result = imap_state_auth_digest_resp_resp(conn, imapcode, imapc->state);
      break;
#endif

#ifdef USE_NTLM
    case IMAP_AUTHENTICATE_NTLM:
      result = imap_state_auth_ntlm_resp(conn, imapcode, imapc->state);
      break;

    case IMAP_AUTHENTICATE_NTLM_TYPE2MSG:
      result = imap_state_auth_ntlm_type2msg_resp(conn, imapcode,
                                                  imapc->state);
      break;
#endif

    case IMAP_AUTHENTICATE_XOAUTH2:
      result = imap_state_auth_xoauth2_resp(conn, imapcode, imapc->state);
      break;

    case IMAP_AUTHENTICATE_CANCEL:
      result = imap_state_auth_cancel_resp(conn, imapcode, imapc->state);
      break;

    case IMAP_AUTHENTICATE_FINAL:
      result = imap_state_auth_final_resp(conn, imapcode, imapc->state);
      break;

    case IMAP_LOGIN:
      result = imap_state_login_resp(conn, imapcode, imapc->state);
      break;

    case IMAP_LIST:
      result = imap_state_list_resp(conn, imapcode, imapc->state);
      break;

    case IMAP_SELECT:
      result = imap_state_select_resp(conn, imapcode, imapc->state);
      break;

    case IMAP_FETCH:
      result = imap_state_fetch_resp(conn, imapcode, imapc->state);
      break;

    case IMAP_FETCH_FINAL:
      result = imap_state_fetch_final_resp(conn, imapcode, imapc->state);
      break;

    case IMAP_APPEND:
      result = imap_state_append_resp(conn, imapcode, imapc->state);
      break;

    case IMAP_APPEND_FINAL:
      result = imap_state_append_final_resp(conn, imapcode, imapc->state);
      break;

    case IMAP_LOGOUT:
      /* fallthrough, just stop! */
    default:
      /* internal error */
      state(conn, IMAP_STOP);
      break;
    }
  } while(!result && imapc->state != IMAP_STOP && Curl_pp_moredata(pp));

  return result;
}

/* Called repeatedly until done from multi.c */
static CURLcode imap_multi_statemach(struct connectdata *conn, bool *done)
{
  CURLcode result = CURLE_OK;
  struct imap_conn *imapc = &conn->proto.imapc;

  if((conn->handler->flags & PROTOPT_SSL) && !imapc->ssldone) {
    result = Curl_ssl_connect_nonblocking(conn, FIRSTSOCKET, &imapc->ssldone);
    if(result || !imapc->ssldone)
      return result;
  }

  result = Curl_pp_statemach(&imapc->pp, FALSE);
  *done = (imapc->state == IMAP_STOP) ? TRUE : FALSE;

  return result;
}

static CURLcode imap_block_statemach(struct connectdata *conn)
{
  CURLcode result = CURLE_OK;
  struct imap_conn *imapc = &conn->proto.imapc;

  while(imapc->state != IMAP_STOP && !result)
    result = Curl_pp_statemach(&imapc->pp, TRUE);

  return result;
}

/* Allocate and initialize the struct IMAP for the current SessionHandle if
   required */
static CURLcode imap_init(struct connectdata *conn)
{
  CURLcode result = CURLE_OK;
  struct SessionHandle *data = conn->data;
  struct IMAP *imap;

  imap = data->req.protop = calloc(sizeof(struct IMAP), 1);
  if(!imap)
    result = CURLE_OUT_OF_MEMORY;

  return result;
}

/* For the IMAP "protocol connect" and "doing" phases only */
static int imap_getsock(struct connectdata *conn, curl_socket_t *socks,
                        int numsocks)
{
  return Curl_pp_getsock(&conn->proto.imapc.pp, socks, numsocks);
}

/***********************************************************************
 *
 * imap_connect()
 *
 * This function should do everything that is to be considered a part of the
 * connection phase.
 *
 * The variable 'done' points to will be TRUE if the protocol-layer connect
 * phase is done when this function returns, or FALSE if not.
 */
static CURLcode imap_connect(struct connectdata *conn, bool *done)
{
  CURLcode result = CURLE_OK;
  struct imap_conn *imapc = &conn->proto.imapc;
  struct pingpong *pp = &imapc->pp;

  *done = FALSE; /* default to not done yet */

  /* We always support persistent connections in IMAP */
  conn->bits.close = FALSE;

  /* Set the default response time-out */
  pp->response_time = RESP_TIMEOUT;
  pp->statemach_act = imap_statemach_act;
  pp->endofresp = imap_endofresp;
  pp->conn = conn;

  /* Set the default preferred authentication type and mechanism */
  imapc->preftype = IMAP_TYPE_ANY;
  imapc->prefmech = SASL_AUTH_ANY;

  /* Initialise the pingpong layer */
  Curl_pp_init(pp);

  /* Parse the URL options */
  result = imap_parse_url_options(conn);
  if(result)
    return result;

  /* Start off waiting for the server greeting response */
  state(conn, IMAP_SERVERGREET);

  /* Start off with an response id of '*' */
  strcpy(imapc->resptag, "*");

  result = imap_multi_statemach(conn, done);

  return result;
}

/***********************************************************************
 *
 * imap_done()
 *
 * The DONE function. This does what needs to be done after a single DO has
 * performed.
 *
 * Input argument is already checked for validity.
 */
static CURLcode imap_done(struct connectdata *conn, CURLcode status,
                          bool premature)
{
  CURLcode result = CURLE_OK;
  struct SessionHandle *data = conn->data;
  struct IMAP *imap = data->req.protop;

  (void)premature;

  if(!imap)
    /* When the easy handle is removed from the multi interface while libcurl
       is still trying to resolve the host name, the IMAP struct is not yet
       initialized. However, the removal action calls Curl_done() which in
       turn calls this function, so we simply return success. */
    return CURLE_OK;

  if(status) {
    conn->bits.close = TRUE; /* marked for closure */
    result = status;         /* use the already set error code */
  }
  else if(!data->set.connect_only && !imap->custom &&
          (imap->uid || data->set.upload)) {
    /* Handle responses after FETCH or APPEND transfer has finished */
    if(!data->set.upload)
      state(conn, IMAP_FETCH_FINAL);
    else {
      /* End the APPEND command first by sending an empty line */
      result = Curl_pp_sendf(&conn->proto.imapc.pp, "%s", "");
      if(!result)
        state(conn, IMAP_APPEND_FINAL);
    }

    /* Run the state-machine

       TODO: when the multi interface is used, this _really_ should be using
       the imap_multi_statemach function but we have no general support for
       non-blocking DONE operations, not in the multi state machine and with
       Curl_done() invokes on several places in the code!
    */
    if(!result)
      result = imap_block_statemach(conn);
  }

  /* Cleanup our per-request based variables */
  Curl_safefree(imap->mailbox);
  Curl_safefree(imap->uidvalidity);
  Curl_safefree(imap->uid);
  Curl_safefree(imap->section);
  Curl_safefree(imap->custom);
  Curl_safefree(imap->custom_params);

  /* Clear the transfer mode for the next request */
  imap->transfer = FTPTRANSFER_BODY;

  return result;
}

/***********************************************************************
 *
 * imap_perform()
 *
 * This is the actual DO function for IMAP. Fetch or append a message, or do
 * other things according to the options previously setup.
 */
static CURLcode imap_perform(struct connectdata *conn, bool *connected,
                             bool *dophase_done)
{
  /* This is IMAP and no proxy */
  CURLcode result = CURLE_OK;
  struct SessionHandle *data = conn->data;
  struct IMAP *imap = data->req.protop;
  struct imap_conn *imapc = &conn->proto.imapc;
  bool selected = FALSE;

  DEBUGF(infof(conn->data, "DO phase starts\n"));

  if(conn->data->set.opt_no_body) {
    /* Requested no body means no transfer */
    imap->transfer = FTPTRANSFER_INFO;
  }

  *dophase_done = FALSE; /* not done yet */

  /* Determine if the requested mailbox (with the same UIDVALIDITY if set)
     has already been selected on this connection */
  if(imap->mailbox && imapc->mailbox &&
     !strcmp(imap->mailbox, imapc->mailbox) &&
     (!imap->uidvalidity || !imapc->mailbox_uidvalidity ||
      !strcmp(imap->uidvalidity, imapc->mailbox_uidvalidity)))
    selected = TRUE;

  /* Start the first command in the DO phase */
  if(conn->data->set.upload)
    /* APPEND can be executed directly */
    result = imap_perform_append(conn);
  else if(imap->custom && (selected || !imap->mailbox))
    /* Custom command using the same mailbox or no mailbox */
    result = imap_perform_list(conn);
  else if(!imap->custom && selected && imap->uid)
    /* FETCH from the same mailbox */
    result = imap_perform_fetch(conn);
  else if(imap->mailbox && !selected && (imap->custom || imap->uid))
    /* SELECT the mailbox */
    result = imap_perform_select(conn);
  else
    /* LIST */
    result = imap_perform_list(conn);

  if(result)
    return result;

  /* Run the state-machine */
  result = imap_multi_statemach(conn, dophase_done);

  *connected = conn->bits.tcpconnect[FIRSTSOCKET];

  if(*dophase_done)
    DEBUGF(infof(conn->data, "DO phase is complete\n"));

  return result;
}

/***********************************************************************
 *
 * imap_do()
 *
 * This function is registered as 'curl_do' function. It decodes the path
 * parts etc as a wrapper to the actual DO function (imap_perform).
 *
 * The input argument is already checked for validity.
 */
static CURLcode imap_do(struct connectdata *conn, bool *done)
{
  CURLcode result = CURLE_OK;

  *done = FALSE; /* default to false */

  /* Parse the URL path */
  result = imap_parse_url_path(conn);
  if(result)
    return result;

  /* Parse the custom request */
  result = imap_parse_custom_request(conn);
  if(result)
    return result;

  result = imap_regular_transfer(conn, done);

  return result;
}

/***********************************************************************
 *
 * imap_disconnect()
 *
 * Disconnect from an IMAP server. Cleanup protocol-specific per-connection
 * resources. BLOCKING.
 */
static CURLcode imap_disconnect(struct connectdata *conn, bool dead_connection)
{
  struct imap_conn *imapc = &conn->proto.imapc;

  /* We cannot send quit unconditionally. If this connection is stale or
     bad in any way, sending quit and waiting around here will make the
     disconnect wait in vain and cause more problems than we need to. */

  /* The IMAP session may or may not have been allocated/setup at this
     point! */
  if(!dead_connection && imapc->pp.conn && imapc->pp.conn->bits.protoconnstart)
    if(!imap_perform_logout(conn))
      (void)imap_block_statemach(conn); /* ignore errors on LOGOUT */

  /* Disconnect from the server */
  Curl_pp_disconnect(&imapc->pp);

  /* Cleanup the SASL module */
  Curl_sasl_cleanup(conn, imapc->authused);

  /* Cleanup our connection based variables */
  Curl_safefree(imapc->mailbox);
  Curl_safefree(imapc->mailbox_uidvalidity);

  return CURLE_OK;
}

/* Call this when the DO phase has completed */
static CURLcode imap_dophase_done(struct connectdata *conn, bool connected)
{
  struct IMAP *imap = conn->data->req.protop;

  (void)connected;

  if(imap->transfer != FTPTRANSFER_BODY)
    /* no data to transfer */
    Curl_setup_transfer(conn, -1, -1, FALSE, NULL, -1, NULL);

  return CURLE_OK;
}

/* Called from multi.c while DOing */
static CURLcode imap_doing(struct connectdata *conn, bool *dophase_done)
{
  CURLcode result = imap_multi_statemach(conn, dophase_done);

  if(result)
    DEBUGF(infof(conn->data, "DO phase failed\n"));
  else if(*dophase_done) {
    result = imap_dophase_done(conn, FALSE /* not connected */);

    DEBUGF(infof(conn->data, "DO phase is complete\n"));
  }

  return result;
}

/***********************************************************************
 *
 * imap_regular_transfer()
 *
 * The input argument is already checked for validity.
 *
 * Performs all commands done before a regular transfer between a local and a
 * remote host.
 */
static CURLcode imap_regular_transfer(struct connectdata *conn,
                                      bool *dophase_done)
{
  CURLcode result = CURLE_OK;
  bool connected = FALSE;
  struct SessionHandle *data = conn->data;

  /* Make sure size is unknown at this point */
  data->req.size = -1;

  /* Set the progress data */
  Curl_pgrsSetUploadCounter(data, 0);
  Curl_pgrsSetDownloadCounter(data, 0);
  Curl_pgrsSetUploadSize(data, 0);
  Curl_pgrsSetDownloadSize(data, 0);

  /* Carry out the perform */
  result = imap_perform(conn, &connected, dophase_done);

  /* Perform post DO phase operations if necessary */
  if(!result && *dophase_done)
    result = imap_dophase_done(conn, connected);

  return result;
}

static CURLcode imap_setup_connection(struct connectdata *conn)
{
  struct SessionHandle *data = conn->data;

  /* Initialise the IMAP layer */
  CURLcode result = imap_init(conn);
  if(result)
    return result;

  if(conn->bits.httpproxy && !data->set.tunnel_thru_httpproxy) {
    /* Unless we have asked to tunnel IMAP operations through the proxy, we
       switch and use HTTP operations only */
#ifndef CURL_DISABLE_HTTP
    if(conn->handler == &Curl_handler_imap)
      conn->handler = &Curl_handler_imap_proxy;
    else {
#ifdef USE_SSL
      conn->handler = &Curl_handler_imaps_proxy;
#else
      failf(data, "IMAPS not supported!");
      return CURLE_UNSUPPORTED_PROTOCOL;
#endif
    }

    /* set it up as an HTTP connection instead */
    return conn->handler->setup_connection(conn);
#else
    failf(data, "IMAP over http proxy requires HTTP support built-in!");
    return CURLE_UNSUPPORTED_PROTOCOL;
#endif
  }

  data->state.path++;   /* don't include the initial slash */

  return CURLE_OK;
}

/***********************************************************************
 *
 * imap_sendf()
 *
 * Sends the formated string as an IMAP command to the server.
 *
 * Designed to never block.
 */
static CURLcode imap_sendf(struct connectdata *conn, const char *fmt, ...)
{
  CURLcode result = CURLE_OK;
  struct imap_conn *imapc = &conn->proto.imapc;
  char *taggedfmt;
  va_list ap;

  DEBUGASSERT(fmt);

  /* Calculate the next command ID wrapping at 3 digits */
  imapc->cmdid = (imapc->cmdid + 1) % 1000;

  /* Calculate the tag based on the connection ID and command ID */
  snprintf(imapc->resptag, sizeof(imapc->resptag), "%c%03d",
           'A' + curlx_sltosi(conn->connection_id % 26), imapc->cmdid);

  /* Prefix the format with the tag */
  taggedfmt = aprintf("%s %s", imapc->resptag, fmt);
  if(!taggedfmt)
    return CURLE_OUT_OF_MEMORY;

  /* Send the data with the tag */
  va_start(ap, fmt);
  result = Curl_pp_vsendf(&imapc->pp, taggedfmt, ap);
  va_end(ap);

  Curl_safefree(taggedfmt);

  return result;
}

/***********************************************************************
 *
 * imap_atom()
 *
 * Checks the input string for characters that need escaping and returns an
 * atom ready for sending to the server.
 *
 * The returned string needs to be freed.
 *
 */
static char *imap_atom(const char *str)
{
  const char *p1;
  char *p2;
  size_t backsp_count = 0;
  size_t quote_count = 0;
  bool space_exists = FALSE;
  size_t newlen = 0;
  char *newstr = NULL;

  if(!str)
    return NULL;

  /* Count any unescapped characters */
  p1 = str;
  while(*p1) {
    if(*p1 == '\\')
      backsp_count++;
    else if(*p1 == '"')
      quote_count++;
    else if(*p1 == ' ')
      space_exists = TRUE;

    p1++;
  }

  /* Does the input contain any unescapped characters? */
  if(!backsp_count && !quote_count && !space_exists)
    return strdup(str);

  /* Calculate the new string length */
  newlen = strlen(str) + backsp_count + quote_count + (space_exists ? 2 : 0);

  /* Allocate the new string */
  newstr = (char *) malloc((newlen + 1) * sizeof(char));
  if(!newstr)
    return NULL;

  /* Surround the string in quotes if necessary */
  p2 = newstr;
  if(space_exists) {
    newstr[0] = '"';
    newstr[newlen - 1] = '"';
    p2++;
  }

  /* Copy the string, escaping backslash and quote characters along the way */
  p1 = str;
  while(*p1) {
    if(*p1 == '\\' || *p1 == '"') {
      *p2 = '\\';
      p2++;
    }

   *p2 = *p1;

    p1++;
    p2++;
  }

  /* Terminate the string */
  newstr[newlen] = '\0';

  return newstr;
}

/***********************************************************************
 *
 * imap_is_bchar()
 *
 * Portable test of whether the specified char is a "bchar" as defined in the
 * grammar of RFC-5092.
 */
static bool imap_is_bchar(char ch)
{
  switch(ch) {
    /* bchar */
    case ':': case '@': case '/':
    /* bchar -> achar */
    case '&': case '=':
    /* bchar -> achar -> uchar -> unreserved */
    case '0': case '1': case '2': case '3': case '4': case '5': case '6':
    case '7': case '8': case '9':
    case 'A': case 'B': case 'C': case 'D': case 'E': case 'F': case 'G':
    case 'H': case 'I': case 'J': case 'K': case 'L': case 'M': case 'N':
    case 'O': case 'P': case 'Q': case 'R': case 'S': case 'T': case 'U':
    case 'V': case 'W': case 'X': case 'Y': case 'Z':
    case 'a': case 'b': case 'c': case 'd': case 'e': case 'f': case 'g':
    case 'h': case 'i': case 'j': case 'k': case 'l': case 'm': case 'n':
    case 'o': case 'p': case 'q': case 'r': case 's': case 't': case 'u':
    case 'v': case 'w': case 'x': case 'y': case 'z':
    case '-': case '.': case '_': case '~':
    /* bchar -> achar -> uchar -> sub-delims-sh */
    case '!': case '$': case '\'': case '(': case ')': case '*':
    case '+': case ',':
    /* bchar -> achar -> uchar -> pct-encoded */
    case '%': /* HEXDIG chars are already included above */
      return true;

    default:
      return false;
  }
}

/***********************************************************************
 *
 * imap_parse_url_options()
 *
 * Parse the URL login options.
 */
static CURLcode imap_parse_url_options(struct connectdata *conn)
{
  CURLcode result = CURLE_OK;
  struct imap_conn *imapc = &conn->proto.imapc;
  const char *options = conn->options;
  const char *ptr = options;

  if(options) {
    const char *key = ptr;

    while(*ptr && *ptr != '=')
        ptr++;

    if(strnequal(key, "AUTH", 4)) {
      const char *value = ptr + 1;

      if(strequal(value, "*")) {
        imapc->preftype = IMAP_TYPE_ANY;
        imapc->prefmech = SASL_AUTH_ANY;
      }
      else if(strequal(value, SASL_MECH_STRING_LOGIN)) {
        imapc->preftype = IMAP_TYPE_SASL;
        imapc->prefmech = SASL_MECH_LOGIN;
      }
      else if(strequal(value, SASL_MECH_STRING_PLAIN)) {
        imapc->preftype = IMAP_TYPE_SASL;
        imapc->prefmech = SASL_MECH_PLAIN;
      }
      else if(strequal(value, SASL_MECH_STRING_CRAM_MD5)) {
        imapc->preftype = IMAP_TYPE_SASL;
        imapc->prefmech = SASL_MECH_CRAM_MD5;
      }
      else if(strequal(value, SASL_MECH_STRING_DIGEST_MD5)) {
        imapc->preftype = IMAP_TYPE_SASL;
        imapc->prefmech = SASL_MECH_DIGEST_MD5;
      }
      else if(strequal(value, SASL_MECH_STRING_GSSAPI)) {
        imapc->preftype = IMAP_TYPE_SASL;
        imapc->prefmech = SASL_MECH_GSSAPI;
      }
      else if(strequal(value, SASL_MECH_STRING_NTLM)) {
        imapc->preftype = IMAP_TYPE_SASL;
        imapc->prefmech = SASL_MECH_NTLM;
      }
      else if(strequal(value, SASL_MECH_STRING_XOAUTH2)) {
        imapc->preftype = IMAP_TYPE_SASL;
        imapc->prefmech = SASL_MECH_XOAUTH2;
      }
      else {
        imapc->preftype = IMAP_TYPE_NONE;
        imapc->prefmech = SASL_AUTH_NONE;
      }
    }
    else
      result = CURLE_URL_MALFORMAT;
  }

  return result;
}

/***********************************************************************
 *
 * imap_parse_url_path()
 *
 * Parse the URL path into separate path components.
 *
 */
static CURLcode imap_parse_url_path(struct connectdata *conn)
{
  /* The imap struct is already initialised in imap_connect() */
  CURLcode result = CURLE_OK;
  struct SessionHandle *data = conn->data;
  struct IMAP *imap = data->req.protop;
  const char *begin = data->state.path;
  const char *ptr = begin;

  /* See how much of the URL is a valid path and decode it */
  while(imap_is_bchar(*ptr))
    ptr++;

  if(ptr != begin) {
    /* Remove the trailing slash if present */
    const char *end = ptr;
    if(end > begin && end[-1] == '/')
      end--;

    result = Curl_urldecode(data, begin, end - begin, &imap->mailbox, NULL,
                            TRUE);
    if(result)
      return result;
  }
  else
    imap->mailbox = NULL;

  /* There can be any number of parameters in the form ";NAME=VALUE" */
  while(*ptr == ';') {
    char *name;
    char *value;
    size_t valuelen;

    /* Find the length of the name parameter */
    begin = ++ptr;
    while(*ptr && *ptr != '=')
      ptr++;

    if(!*ptr)
      return CURLE_URL_MALFORMAT;

    /* Decode the name parameter */
    result = Curl_urldecode(data, begin, ptr - begin, &name, NULL, TRUE);
    if(result)
      return result;

    /* Find the length of the value parameter */
    begin = ++ptr;
    while(imap_is_bchar(*ptr))
      ptr++;

    /* Decode the value parameter */
    result = Curl_urldecode(data, begin, ptr - begin, &value, &valuelen, TRUE);
    if(result) {
      Curl_safefree(name);
      return result;
    }

    DEBUGF(infof(conn->data, "IMAP URL parameter '%s' = '%s'\n", name, value));

    /* Process the known hierarchical parameters (UIDVALIDITY, UID and SECTION)
       stripping of the trailing slash character if it is present.

       Note: Unknown parameters trigger a URL_MALFORMAT error. */
    if(Curl_raw_equal(name, "UIDVALIDITY") && !imap->uidvalidity) {
      if(valuelen > 0 && value[valuelen - 1] == '/')
        value[valuelen - 1] = '\0';

      imap->uidvalidity = value;
      value = NULL;
    }
    else if(Curl_raw_equal(name, "UID") && !imap->uid) {
      if(valuelen > 0 && value[valuelen - 1] == '/')
        value[valuelen - 1] = '\0';

      imap->uid = value;
      value = NULL;
    }
    else if(Curl_raw_equal(name, "SECTION") && !imap->section) {
      if(valuelen > 0 && value[valuelen - 1] == '/')
        value[valuelen - 1] = '\0';

      imap->section = value;
      value = NULL;
    }
    else {
      Curl_safefree(name);
      Curl_safefree(value);

      return CURLE_URL_MALFORMAT;
    }

    Curl_safefree(name);
    Curl_safefree(value);
  }

  /* Any extra stuff at the end of the URL is an error */
  if(*ptr)
    return CURLE_URL_MALFORMAT;

  return CURLE_OK;
}

/***********************************************************************
 *
 * imap_parse_custom_request()
 *
 * Parse the custom request.
 */
static CURLcode imap_parse_custom_request(struct connectdata *conn)
{
  CURLcode result = CURLE_OK;
  struct SessionHandle *data = conn->data;
  struct IMAP *imap = data->req.protop;
  const char *custom = data->set.str[STRING_CUSTOMREQUEST];

  if(custom) {
    /* URL decode the custom request */
    result = Curl_urldecode(data, custom, 0, &imap->custom, NULL, TRUE);

    /* Extract the parameters if specified */
    if(!result) {
      const char *params = imap->custom;

      while(*params && *params != ' ')
        params++;

      if(*params) {
        imap->custom_params = strdup(params);
        imap->custom[params - imap->custom] = '\0';

        if(!imap->custom_params)
          result = CURLE_OUT_OF_MEMORY;
      }
    }
  }

  return result;
}

#endif /* CURL_DISABLE_IMAP */