summaryrefslogtreecommitdiff
path: root/lib/smtp.c
blob: 550725a93edd338dcc1061cadd5c649712444bd6 (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
/***************************************************************************
 *                                  _   _ ____  _
 *  Project                     ___| | | |  _ \| |
 *                             / __| | | | |_) | |
 *                            | (__| |_| |  _ <| |___
 *                             \___|\___/|_| \_\_____|
 *
 * Copyright (C) 1998 - 2015, 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.
 *
 * RFC1870 SMTP Service Extension for Message Size
 * RFC2195 CRAM-MD5 authentication
 * RFC2831 DIGEST-MD5 authentication
 * RFC3207 SMTP over TLS
 * RFC4422 Simple Authentication and Security Layer (SASL)
 * RFC4616 PLAIN authentication
 * RFC4752 The Kerberos V5 ("GSSAPI") SASL Mechanism
 * RFC4954 SMTP Authentication
 * RFC5321 SMTP protocol
 * RFC6749 OAuth 2.0 Authorization Framework
 * Draft   SMTP URL Interface   <draft-earhart-url-smtp-00.txt>
 * Draft   LOGIN SASL Mechanism <draft-murchison-sasl-login-00.txt>
 *
 ***************************************************************************/

#include "curl_setup.h"

#ifndef CURL_DISABLE_SMTP

#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 "hostip.h"
#include "progress.h"
#include "transfer.h"
#include "escape.h"
#include "http.h" /* for HTTP proxy tunnel stuff */
#include "socks.h"
#include "smtp.h"

#include "strtoofft.h"
#include "strequal.h"
#include "vtls/vtls.h"
#include "connect.h"
#include "strerror.h"
#include "select.h"
#include "multiif.h"
#include "url.h"
#include "rawstr.h"
#include "curl_gethostname.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 smtp_regular_transfer(struct connectdata *conn, bool *done);
static CURLcode smtp_do(struct connectdata *conn, bool *done);
static CURLcode smtp_done(struct connectdata *conn, CURLcode status,
                          bool premature);
static CURLcode smtp_connect(struct connectdata *conn, bool *done);
static CURLcode smtp_disconnect(struct connectdata *conn, bool dead);
static CURLcode smtp_multi_statemach(struct connectdata *conn, bool *done);
static int smtp_getsock(struct connectdata *conn, curl_socket_t *socks,
                        int numsocks);
static CURLcode smtp_doing(struct connectdata *conn, bool *dophase_done);
static CURLcode smtp_setup_connection(struct connectdata *conn);
static CURLcode smtp_parse_url_options(struct connectdata *conn);
static CURLcode smtp_parse_url_path(struct connectdata *conn);
static CURLcode smtp_parse_custom_request(struct connectdata *conn);
static CURLcode smtp_perform_auth(struct connectdata *conn, const char *mech,
                                  const char *initresp);
static CURLcode smtp_continue_auth(struct connectdata *conn, const char *resp);
static void smtp_get_message(char *buffer, char** outptr);

/*
 * SMTP protocol handler.
 */

const struct Curl_handler Curl_handler_smtp = {
  "SMTP",                           /* scheme */
  smtp_setup_connection,            /* setup_connection */
  smtp_do,                          /* do_it */
  smtp_done,                        /* done */
  ZERO_NULL,                        /* do_more */
  smtp_connect,                     /* connect_it */
  smtp_multi_statemach,             /* connecting */
  smtp_doing,                       /* doing */
  smtp_getsock,                     /* proto_getsock */
  smtp_getsock,                     /* doing_getsock */
  ZERO_NULL,                        /* domore_getsock */
  ZERO_NULL,                        /* perform_getsock */
  smtp_disconnect,                  /* disconnect */
  ZERO_NULL,                        /* readwrite */
  PORT_SMTP,                        /* defport */
  CURLPROTO_SMTP,                   /* protocol */
  PROTOPT_CLOSEACTION | PROTOPT_NOURLQUERY /* flags */
};

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

const struct Curl_handler Curl_handler_smtps = {
  "SMTPS",                          /* scheme */
  smtp_setup_connection,            /* setup_connection */
  smtp_do,                          /* do_it */
  smtp_done,                        /* done */
  ZERO_NULL,                        /* do_more */
  smtp_connect,                     /* connect_it */
  smtp_multi_statemach,             /* connecting */
  smtp_doing,                       /* doing */
  smtp_getsock,                     /* proto_getsock */
  smtp_getsock,                     /* doing_getsock */
  ZERO_NULL,                        /* domore_getsock */
  ZERO_NULL,                        /* perform_getsock */
  smtp_disconnect,                  /* disconnect */
  ZERO_NULL,                        /* readwrite */
  PORT_SMTPS,                       /* defport */
  CURLPROTO_SMTPS,                  /* protocol */
  PROTOPT_CLOSEACTION | PROTOPT_SSL
  | PROTOPT_NOURLQUERY              /* flags */
};
#endif

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

static const struct Curl_handler Curl_handler_smtp_proxy = {
  "SMTP",                               /* 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_SMTP,                            /* defport */
  CURLPROTO_HTTP,                       /* protocol */
  PROTOPT_NONE                          /* flags */
};

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

static const struct Curl_handler Curl_handler_smtps_proxy = {
  "SMTPS",                              /* 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_SMTPS,                           /* defport */
  CURLPROTO_HTTP,                       /* protocol */
  PROTOPT_NONE                          /* flags */
};
#endif
#endif

/* SASL parameters for the smtp protocol */
static const struct SASLproto saslsmtp = {
  "smtp",                     /* The service name */
  334,                        /* Code received when continuation is expected */
  235,                        /* Code to receive upon authentication success */
  512 - 8,                    /* Maximum initial response length (no max) */
  smtp_perform_auth,          /* Send authentication command */
  smtp_continue_auth,         /* Send authentication continuation */
  smtp_get_message            /* Get SASL response message */
};

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

/***********************************************************************
 *
 * smtp_endofresp()
 *
 * Checks for an ending SMTP status code at the start of the given string, but
 * also detects various capabilities from the EHLO response including the
 * supported authentication mechanisms.
 */
static bool smtp_endofresp(struct connectdata *conn, char *line, size_t len,
                           int *resp)
{
  struct smtp_conn *smtpc = &conn->proto.smtpc;
  bool result = FALSE;

  /* Nothing for us */
  if(len < 4 || !ISDIGIT(line[0]) || !ISDIGIT(line[1]) || !ISDIGIT(line[2]))
    return FALSE;

  /* Do we have a command response? This should be the response code followed
     by a space and optionally some text as per RFC-5321 and as outlined in
     Section 4. Examples of RFC-4954 but some e-mail servers ignore this and
     only send the response code instead as per Section 4.2. */
  if(line[3] == ' ' || len == 5) {
    result = TRUE;
    *resp = curlx_sltosi(strtol(line, NULL, 10));

    /* Make sure real server never sends internal value */
    if(*resp == 1)
      *resp = 0;
  }
  /* Do we have a multiline (continuation) response? */
  else if(line[3] == '-' &&
          (smtpc->state == SMTP_EHLO || smtpc->state == SMTP_COMMAND)) {
    result = TRUE;
    *resp = 1;  /* Internal response code */
  }

  return result;
}

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

  /* Find the start of the message */
  for(message = buffer + 4; *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 SMTP state!
 */
static void state(struct connectdata *conn, smtpstate newstate)
{
  struct smtp_conn *smtpc = &conn->proto.smtpc;
#if defined(DEBUGBUILD) && !defined(CURL_DISABLE_VERBOSE_STRINGS)
  /* for debug purposes */
  static const char * const names[] = {
    "STOP",
    "SERVERGREET",
    "EHLO",
    "HELO",
    "STARTTLS",
    "UPGRADETLS",
    "AUTH",
    "COMMAND",
    "MAIL",
    "RCPT",
    "DATA",
    "POSTDATA",
    "QUIT",
    /* LAST */
  };

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

  smtpc->state = newstate;
}

/***********************************************************************
 *
 * smtp_perform_ehlo()
 *
 * Sends the EHLO command to not only initialise communication with the ESMTP
 * server but to also obtain a list of server side supported capabilities.
 */
static CURLcode smtp_perform_ehlo(struct connectdata *conn)
{
  CURLcode result = CURLE_OK;
  struct smtp_conn *smtpc = &conn->proto.smtpc;

  smtpc->sasl.authmechs = SASL_AUTH_NONE; /* No known auth. mechanism yet */
  smtpc->sasl.authused = SASL_AUTH_NONE;  /* Clear the authentication mechanism
                                             used for esmtp connections */
  smtpc->tls_supported = FALSE;           /* Clear the TLS capability */
  smtpc->auth_supported = FALSE;          /* Clear the AUTH capability */

  /* Send the EHLO command */
  result = Curl_pp_sendf(&smtpc->pp, "EHLO %s", smtpc->domain);

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

  return result;
}

/***********************************************************************
 *
 * smtp_perform_helo()
 *
 * Sends the HELO command to initialise communication with the SMTP server.
 */
static CURLcode smtp_perform_helo(struct connectdata *conn)
{
  CURLcode result = CURLE_OK;
  struct smtp_conn *smtpc = &conn->proto.smtpc;

  smtpc->sasl.authused = SASL_AUTH_NONE; /* No authentication mechanism used
                                            in smtp connections */

  /* Send the HELO command */
  result = Curl_pp_sendf(&smtpc->pp, "HELO %s", smtpc->domain);

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

  return result;
}

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

  /* Send the STARTTLS command */
  result = Curl_pp_sendf(&conn->proto.smtpc.pp, "%s", "STARTTLS");

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

  return result;
}

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

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

  if(!result) {
    if(smtpc->state != SMTP_UPGRADETLS)
      state(conn, SMTP_UPGRADETLS);

    if(smtpc->ssldone) {
      smtp_to_smtps(conn);
      result = smtp_perform_ehlo(conn);
    }
  }

  return result;
}

/***********************************************************************
 *
 * smtp_perform_auth()
 *
 * Sends an AUTH command allowing the client to login with the given SASL
 * authentication mechanism.
 */
static CURLcode smtp_perform_auth(struct connectdata *conn,
                                  const char *mech,
                                  const char *initresp)
{
  CURLcode result = CURLE_OK;
  struct smtp_conn *smtpc = &conn->proto.smtpc;

  if(initresp) {                                  /* AUTH <mech> ...<crlf> */
    /* Send the AUTH command with the initial response */
    result = Curl_pp_sendf(&smtpc->pp, "AUTH %s %s", mech, initresp);
  }
  else {
    /* Send the AUTH command */
    result = Curl_pp_sendf(&smtpc->pp, "AUTH %s", mech);
  }

  return result;
}

/***********************************************************************
 *
 * smtp_continue_auth()
 *
 * Sends SASL continuation data or cancellation.
 */
static CURLcode smtp_continue_auth(struct connectdata *conn, const char *resp)
{
  struct smtp_conn *smtpc = &conn->proto.smtpc;

  return Curl_pp_sendf(&smtpc->pp, "%s", resp);
}

/***********************************************************************
 *
 * smtp_perform_authentication()
 *
 * Initiates the authentication sequence, with the appropriate SASL
 * authentication mechanism.
 */
static CURLcode smtp_perform_authentication(struct connectdata *conn)
{
  CURLcode result = CURLE_OK;
  struct smtp_conn *smtpc = &conn->proto.smtpc;
  saslprogress progress;

  /* Check we have enough data to authenticate with, and the
     server supports authentiation, and end the connect phase if not */
  if(!smtpc->auth_supported ||
      !Curl_sasl_can_authenticate(&smtpc->sasl, conn)) {
    state(conn, SMTP_STOP);
    return result;
  }

  /* Calculate the SASL login details */
  result = Curl_sasl_start(&smtpc->sasl, conn, FALSE, &progress);

  if(!result) {
    if(progress == SASL_INPROGRESS)
      state(conn, SMTP_AUTH);
    else {
      /* Other mechanisms not supported */
      infof(conn->data, "No known authentication mechanisms supported!\n");
      result = CURLE_LOGIN_DENIED;
    }
  }

  return result;
}

/***********************************************************************
 *
 * smtp_perform_command()
 *
 * Sends a SMTP based command.
 */
static CURLcode smtp_perform_command(struct connectdata *conn)
{
  CURLcode result = CURLE_OK;
  struct SessionHandle *data = conn->data;
  struct SMTP *smtp = data->req.protop;

  /* Send the command */
  if(smtp->rcpt)
    result = Curl_pp_sendf(&conn->proto.smtpc.pp, "%s %s",
                            smtp->custom && smtp->custom[0] != '\0' ?
                            smtp->custom : "VRFY",
                            smtp->rcpt->data);
  else
    result = Curl_pp_sendf(&conn->proto.smtpc.pp, "%s",
                           smtp->custom && smtp->custom[0] != '\0' ?
                           smtp->custom : "HELP");

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

  return result;
}

/***********************************************************************
 *
 * smtp_perform_mail()
 *
 * Sends an MAIL command to initiate the upload of a message.
 */
static CURLcode smtp_perform_mail(struct connectdata *conn)
{
  char *from = NULL;
  char *auth = NULL;
  char *size = NULL;
  CURLcode result = CURLE_OK;
  struct SessionHandle *data = conn->data;

  /* Calculate the FROM parameter */
  if(!data->set.str[STRING_MAIL_FROM])
    /* Null reverse-path, RFC-5321, sect. 3.6.3 */
    from = strdup("<>");
  else if(data->set.str[STRING_MAIL_FROM][0] == '<')
    from = aprintf("%s", data->set.str[STRING_MAIL_FROM]);
  else
    from = aprintf("<%s>", data->set.str[STRING_MAIL_FROM]);

  if(!from)
    return CURLE_OUT_OF_MEMORY;

  /* Calculate the optional AUTH parameter */
  if(data->set.str[STRING_MAIL_AUTH] && conn->proto.smtpc.sasl.authused) {
    if(data->set.str[STRING_MAIL_AUTH][0] != '\0')
      auth = aprintf("%s", data->set.str[STRING_MAIL_AUTH]);
    else
      /* Empty AUTH, RFC-2554, sect. 5 */
      auth = strdup("<>");

    if(!auth) {
      Curl_safefree(from);

      return CURLE_OUT_OF_MEMORY;
    }
  }

  /* Calculate the optional SIZE parameter */
  if(conn->proto.smtpc.size_supported && conn->data->state.infilesize > 0) {
    size = aprintf("%" CURL_FORMAT_CURL_OFF_T, data->state.infilesize);

    if(!size) {
      Curl_safefree(from);
      Curl_safefree(auth);

      return CURLE_OUT_OF_MEMORY;
    }
  }

  /* Send the MAIL command */
  if(!auth && !size)
    result = Curl_pp_sendf(&conn->proto.smtpc.pp,
                           "MAIL FROM:%s", from);
  else if(auth && !size)
    result = Curl_pp_sendf(&conn->proto.smtpc.pp,
                           "MAIL FROM:%s AUTH=%s", from, auth);
  else if(auth && size)
    result = Curl_pp_sendf(&conn->proto.smtpc.pp,
                           "MAIL FROM:%s AUTH=%s SIZE=%s", from, auth, size);
  else
    result = Curl_pp_sendf(&conn->proto.smtpc.pp,
                           "MAIL FROM:%s SIZE=%s", from, size);

  Curl_safefree(from);
  Curl_safefree(auth);
  Curl_safefree(size);

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

  return result;
}

/***********************************************************************
 *
 * smtp_perform_rcpt_to()
 *
 * Sends a RCPT TO command for a given recipient as part of the message upload
 * process.
 */
static CURLcode smtp_perform_rcpt_to(struct connectdata *conn)
{
  CURLcode result = CURLE_OK;
  struct SessionHandle *data = conn->data;
  struct SMTP *smtp = data->req.protop;

  /* Send the RCPT TO command */
  if(smtp->rcpt->data[0] == '<')
    result = Curl_pp_sendf(&conn->proto.smtpc.pp, "RCPT TO:%s",
                            smtp->rcpt->data);
  else
    result = Curl_pp_sendf(&conn->proto.smtpc.pp, "RCPT TO:<%s>",
                            smtp->rcpt->data);
  if(!result)
    state(conn, SMTP_RCPT);

  return result;
}

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

  /* Send the QUIT command */
  result = Curl_pp_sendf(&conn->proto.smtpc.pp, "%s", "QUIT");

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

  return result;
}

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

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

  if(smtpcode/100 != 2) {
    failf(data, "Got unexpected smtp-server response: %d", smtpcode);
    result = CURLE_FTP_WEIRD_SERVER_REPLY;
  }
  else
    result = smtp_perform_ehlo(conn);

  return result;
}

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

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

  if(smtpcode != 220) {
    if(data->set.use_ssl != CURLUSESSL_TRY) {
      failf(data, "STARTTLS denied. %c", smtpcode);
      result = CURLE_USE_SSL_FAILED;
    }
    else
      result = smtp_perform_authentication(conn);
  }
  else
    result = smtp_perform_upgrade_tls(conn);

  return result;
}

/* For EHLO responses */
static CURLcode smtp_state_ehlo_resp(struct connectdata *conn, int smtpcode,
                                     smtpstate instate)
{
  CURLcode result = CURLE_OK;
  struct SessionHandle *data = conn->data;
  struct smtp_conn *smtpc = &conn->proto.smtpc;
  const char *line = data->state.buffer;
  size_t len = strlen(line);
  size_t wordlen;

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

  if(smtpcode/100 != 2 && smtpcode != 1) {
    if(data->set.use_ssl <= CURLUSESSL_TRY || conn->ssl[FIRSTSOCKET].use)
      result = smtp_perform_helo(conn);
    else {
      failf(data, "Remote access denied: %d", smtpcode);
      result = CURLE_REMOTE_ACCESS_DENIED;
    }
  }
  else {
    line += 4;
    len -= 4;

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

    /* Does the server support the SIZE capability? */
    else if(len >= 4 && !memcmp(line, "SIZE", 4))
      smtpc->size_supported = TRUE;

    /* Does the server support authentication? */
    else if(len >= 5 && !memcmp(line, "AUTH ", 5)) {
      smtpc->auth_supported = TRUE;

      /* Advance past the AUTH keyword */
      line += 5;
      len -= 5;

      /* Loop through the data line */
      for(;;) {
        size_t llen;
        unsigned int mechbit;

        while(len &&
              (*line == ' ' || *line == '\t' ||
               *line == '\r' || *line == '\n')) {

          line++;
          len--;
        }

        if(!len)
          break;

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

        /* Test the word for a matching authentication mechanism */
        if((mechbit = Curl_sasl_decode_mech(line, wordlen, &llen)) &&
           llen == wordlen)
          smtpc->sasl.authmechs |= mechbit;

        line += wordlen;
        len -= wordlen;
      }
    }

    if(smtpcode != 1) {
      if(data->set.use_ssl && !conn->ssl[FIRSTSOCKET].use) {
        /* We don't have a SSL/TLS connection yet, but SSL is requested */
        if(smtpc->tls_supported)
          /* Switch to TLS connection now */
          result = smtp_perform_starttls(conn);
        else if(data->set.use_ssl == CURLUSESSL_TRY)
          /* Fallback and carry on with authentication */
          result = smtp_perform_authentication(conn);
        else {
          failf(data, "STARTTLS not supported.");
          result = CURLE_USE_SSL_FAILED;
        }
      }
      else
        result = smtp_perform_authentication(conn);
    }
  }

  return result;
}

/* For HELO responses */
static CURLcode smtp_state_helo_resp(struct connectdata *conn, int smtpcode,
                                     smtpstate instate)
{
  CURLcode result = CURLE_OK;
  struct SessionHandle *data = conn->data;

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

  if(smtpcode/100 != 2) {
    failf(data, "Remote access denied: %d", smtpcode);
    result = CURLE_REMOTE_ACCESS_DENIED;
  }
  else
    /* End of connect phase */
    state(conn, SMTP_STOP);

  return result;
}

/* For SASL authentication responses */
static CURLcode smtp_state_auth_resp(struct connectdata *conn,
                                     int smtpcode,
                                     smtpstate instate)
{
  CURLcode result = CURLE_OK;
  struct SessionHandle *data = conn->data;
  struct smtp_conn *smtpc = &conn->proto.smtpc;
  saslprogress progress;

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

  result = Curl_sasl_continue(&smtpc->sasl, conn, smtpcode, &progress);
  if(!result)
    switch(progress) {
    case SASL_DONE:
      state(conn, SMTP_STOP);  /* Authenticated */
      break;
    case SASL_IDLE:            /* No mechanism left after cancellation */
      failf(data, "Authentication cancelled");
      result = CURLE_LOGIN_DENIED;
      break;
    default:
      break;
    }

  return result;
}

/* For command responses */
static CURLcode smtp_state_command_resp(struct connectdata *conn, int smtpcode,
                                        smtpstate instate)
{
  CURLcode result = CURLE_OK;
  struct SessionHandle *data = conn->data;
  struct SMTP *smtp = data->req.protop;
  char *line = data->state.buffer;
  size_t len = strlen(line);

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

  if((smtp->rcpt && smtpcode/100 != 2 && smtpcode != 553 && smtpcode != 1) ||
     (!smtp->rcpt && smtpcode/100 != 2 && smtpcode != 1)) {
    failf(data, "Command failed: %d", smtpcode);
    result = CURLE_RECV_ERROR;
  }
  else {
    /* Temporarily add the LF character back and send as body to the client */
    if(!data->set.opt_no_body) {
      line[len] = '\n';
      result = Curl_client_write(conn, CLIENTWRITE_BODY, line, len + 1);
      line[len] = '\0';
    }

    if(smtpcode != 1) {
      if(smtp->rcpt) {
        smtp->rcpt = smtp->rcpt->next;

        if(smtp->rcpt) {
          /* Send the next command */
          result = smtp_perform_command(conn);
        }
        else
          /* End of DO phase */
          state(conn, SMTP_STOP);
      }
      else
        /* End of DO phase */
        state(conn, SMTP_STOP);
    }
  }

  return result;
}

/* For MAIL responses */
static CURLcode smtp_state_mail_resp(struct connectdata *conn, int smtpcode,
                                     smtpstate instate)
{
  CURLcode result = CURLE_OK;
  struct SessionHandle *data = conn->data;

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

  if(smtpcode/100 != 2) {
    failf(data, "MAIL failed: %d", smtpcode);
    result = CURLE_SEND_ERROR;
  }
  else
    /* Start the RCPT TO command */
    result = smtp_perform_rcpt_to(conn);

  return result;
}

/* For RCPT responses */
static CURLcode smtp_state_rcpt_resp(struct connectdata *conn, int smtpcode,
                                     smtpstate instate)
{
  CURLcode result = CURLE_OK;
  struct SessionHandle *data = conn->data;
  struct SMTP *smtp = data->req.protop;

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

  if(smtpcode/100 != 2) {
    failf(data, "RCPT failed: %d", smtpcode);
    result = CURLE_SEND_ERROR;
  }
  else {
    smtp->rcpt = smtp->rcpt->next;

    if(smtp->rcpt)
      /* Send the next RCPT TO command */
      result = smtp_perform_rcpt_to(conn);
    else {
      /* Send the DATA command */
      result = Curl_pp_sendf(&conn->proto.smtpc.pp, "%s", "DATA");

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

  return result;
}

/* For DATA response */
static CURLcode smtp_state_data_resp(struct connectdata *conn, int smtpcode,
                                     smtpstate instate)
{
  CURLcode result = CURLE_OK;
  struct SessionHandle *data = conn->data;

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

  if(smtpcode != 354) {
    failf(data, "DATA failed: %d", smtpcode);
    result = CURLE_SEND_ERROR;
  }
  else {
    /* Set the progress upload size */
    Curl_pgrsSetUploadSize(data, data->state.infilesize);

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

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

  return result;
}

/* For POSTDATA responses, which are received after the entire DATA
   part has been sent to the server */
static CURLcode smtp_state_postdata_resp(struct connectdata *conn,
                                         int smtpcode,
                                         smtpstate instate)
{
  CURLcode result = CURLE_OK;

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

  if(smtpcode != 250)
    result = CURLE_RECV_ERROR;

  /* End of DONE phase */
  state(conn, SMTP_STOP);

  return result;
}

static CURLcode smtp_statemach_act(struct connectdata *conn)
{
  CURLcode result = CURLE_OK;
  curl_socket_t sock = conn->sock[FIRSTSOCKET];
  struct SessionHandle *data = conn->data;
  int smtpcode;
  struct smtp_conn *smtpc = &conn->proto.smtpc;
  struct pingpong *pp = &smtpc->pp;
  size_t nread = 0;

  /* Busy upgrading the connection; right now all I/O is SSL/TLS, not SMTP */
  if(smtpc->state == SMTP_UPGRADETLS)
    return smtp_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, &smtpcode, &nread);
    if(result)
      return result;

    /* Store the latest response for later retrieval if necessary */
    if(smtpc->state != SMTP_QUIT && smtpcode != 1)
      data->info.httpcode = smtpcode;

    if(!smtpcode)
      break;

    /* We have now received a full SMTP server response */
    switch(smtpc->state) {
    case SMTP_SERVERGREET:
      result = smtp_state_servergreet_resp(conn, smtpcode, smtpc->state);
      break;

    case SMTP_EHLO:
      result = smtp_state_ehlo_resp(conn, smtpcode, smtpc->state);
      break;

    case SMTP_HELO:
      result = smtp_state_helo_resp(conn, smtpcode, smtpc->state);
      break;

    case SMTP_STARTTLS:
      result = smtp_state_starttls_resp(conn, smtpcode, smtpc->state);
      break;

    case SMTP_AUTH:
      result = smtp_state_auth_resp(conn, smtpcode, smtpc->state);
      break;

    case SMTP_COMMAND:
      result = smtp_state_command_resp(conn, smtpcode, smtpc->state);
      break;

    case SMTP_MAIL:
      result = smtp_state_mail_resp(conn, smtpcode, smtpc->state);
      break;

    case SMTP_RCPT:
      result = smtp_state_rcpt_resp(conn, smtpcode, smtpc->state);
      break;

    case SMTP_DATA:
      result = smtp_state_data_resp(conn, smtpcode, smtpc->state);
      break;

    case SMTP_POSTDATA:
      result = smtp_state_postdata_resp(conn, smtpcode, smtpc->state);
      break;

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

  return result;
}

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

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

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

  return result;
}

static CURLcode smtp_block_statemach(struct connectdata *conn)
{
  CURLcode result = CURLE_OK;
  struct smtp_conn *smtpc = &conn->proto.smtpc;

  while(smtpc->state != SMTP_STOP && !result)
    result = Curl_pp_statemach(&smtpc->pp, TRUE);

  return result;
}

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

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

  return result;
}

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

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

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

  /* We always support persistent connections in SMTP */
  connkeep(conn, "SMTP default");

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

  /* Initialize the SASL storage */
  Curl_sasl_init(&smtpc->sasl, &saslsmtp);

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

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

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

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

  result = smtp_multi_statemach(conn, done);

  return result;
}

/***********************************************************************
 *
 * smtp_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 smtp_done(struct connectdata *conn, CURLcode status,
                          bool premature)
{
  CURLcode result = CURLE_OK;
  struct SessionHandle *data = conn->data;
  struct SMTP *smtp = data->req.protop;
  struct pingpong *pp = &conn->proto.smtpc.pp;
  char *eob;
  ssize_t len;
  ssize_t bytes_written;

  (void)premature;

  if(!smtp || !pp->conn)
    /* When the easy handle is removed from the multi interface while libcurl
       is still trying to resolve the host name, the SMTP 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) {
    connclose(conn, "SMTP done with bad status"); /* marked for closure */
    result = status;         /* use the already set error code */
  }
  else if(!data->set.connect_only && data->set.upload && data->set.mail_rcpt) {
    /* Calculate the EOB taking into account any terminating CRLF from the
       previous line of the email or the CRLF of the DATA command when there
       is "no mail data". RFC-5321, sect. 4.1.1.4.

       Note: As some SSL backends, such as OpenSSL, will cause Curl_write() to
       fail when using a different pointer following a previous write, that
       returned CURLE_AGAIN, we duplicate the EOB now rather than when the
       bytes written doesn't equal len. */
    if(smtp->trailing_crlf || !conn->data->state.infilesize) {
      eob = strdup(SMTP_EOB + 2);
      len = SMTP_EOB_LEN - 2;
    }
    else {
      eob = strdup(SMTP_EOB);
      len = SMTP_EOB_LEN;
    }

    if(!eob)
      return CURLE_OUT_OF_MEMORY;

    /* Send the end of block data */
    result = Curl_write(conn, conn->writesockfd, eob, len, &bytes_written);
    if(result) {
      free(eob);
      return result;
    }

    if(bytes_written != len) {
      /* The whole chunk was not sent so keep it around and adjust the
         pingpong structure accordingly */
      pp->sendthis = eob;
      pp->sendsize = len;
      pp->sendleft = len - bytes_written;
    }
    else {
      /* Successfully sent so adjust the response timeout relative to now */
      pp->response = Curl_tvnow();

      free(eob);
    }

    state(conn, SMTP_POSTDATA);

    /* Run the state-machine

       TODO: when the multi interface is used, this _really_ should be using
       the smtp_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!
    */
    result = smtp_block_statemach(conn);
  }

  /* Cleanup our per-request based variables */
  Curl_safefree(smtp->custom);

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

  return result;
}

/***********************************************************************
 *
 * smtp_perform()
 *
 * This is the actual DO function for SMTP. Transfer a mail, send a command
 * or get some data according to the options previously setup.
 */
static CURLcode smtp_perform(struct connectdata *conn, bool *connected,
                             bool *dophase_done)
{
  /* This is SMTP and no proxy */
  CURLcode result = CURLE_OK;
  struct SessionHandle *data = conn->data;
  struct SMTP *smtp = data->req.protop;

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

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

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

  /* Store the first recipient (or NULL if not specified) */
  smtp->rcpt = data->set.mail_rcpt;

  /* Start the first command in the DO phase */
  if(data->set.upload && data->set.mail_rcpt)
    /* MAIL transfer */
    result = smtp_perform_mail(conn);
  else
    /* SMTP based command (VRFY, EXPN, NOOP, RSET or HELP) */
    result = smtp_perform_command(conn);

  if(result)
    return result;

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

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

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

  return result;
}

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

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

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

  result = smtp_regular_transfer(conn, done);

  return result;
}

/***********************************************************************
 *
 * smtp_disconnect()
 *
 * Disconnect from an SMTP server. Cleanup protocol-specific per-connection
 * resources. BLOCKING.
 */
static CURLcode smtp_disconnect(struct connectdata *conn, bool dead_connection)
{
  struct smtp_conn *smtpc = &conn->proto.smtpc;

  /* 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 SMTP session may or may not have been allocated/setup at this
     point! */
  if(!dead_connection && smtpc->pp.conn && smtpc->pp.conn->bits.protoconnstart)
    if(!smtp_perform_quit(conn))
      (void)smtp_block_statemach(conn); /* ignore errors on QUIT */

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

  /* Cleanup the SASL module */
  Curl_sasl_cleanup(conn, smtpc->sasl.authused);

  /* Cleanup our connection based variables */
  Curl_safefree(smtpc->domain);

  return CURLE_OK;
}

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

  (void)connected;

  if(smtp->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 smtp_doing(struct connectdata *conn, bool *dophase_done)
{
  CURLcode result = smtp_multi_statemach(conn, dophase_done);

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

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

  return result;
}

/***********************************************************************
 *
 * smtp_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 smtp_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, -1);
  Curl_pgrsSetDownloadSize(data, -1);

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

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

  return result;
}

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

  if(conn->bits.httpproxy && !data->set.tunnel_thru_httpproxy) {
    /* Unless we have asked to tunnel SMTP operations through the proxy, we
       switch and use HTTP operations only */
#ifndef CURL_DISABLE_HTTP
    if(conn->handler == &Curl_handler_smtp)
      conn->handler = &Curl_handler_smtp_proxy;
    else {
#ifdef USE_SSL
      conn->handler = &Curl_handler_smtps_proxy;
#else
      failf(data, "SMTPS not supported!");
      return CURLE_UNSUPPORTED_PROTOCOL;
#endif
    }
    /* set it up as a HTTP connection instead */
    return conn->handler->setup_connection(conn);

#else
    failf(data, "SMTP over http proxy requires HTTP support built-in!");
    return CURLE_UNSUPPORTED_PROTOCOL;
#endif
  }

  /* Initialise the SMTP layer */
  result = smtp_init(conn);
  if(result)
    return result;

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

  return CURLE_OK;
}

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

  smtpc->sasl.resetprefs = TRUE;

  while(!result && ptr && *ptr) {
    const char *key = ptr;
    const char *value;

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

    value = ptr + 1;

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

    if(strnequal(key, "AUTH=", 5))
      result = Curl_sasl_parse_url_auth_option(&smtpc->sasl,
                                               value, ptr - value);
    else
      result = CURLE_URL_MALFORMAT;

    if(*ptr == ';')
      ptr++;
  }

  return result;
}

/***********************************************************************
 *
 * smtp_parse_url_path()
 *
 * Parse the URL path into separate path components.
 */
static CURLcode smtp_parse_url_path(struct connectdata *conn)
{
  /* The SMTP struct is already initialised in smtp_connect() */
  struct SessionHandle *data = conn->data;
  struct smtp_conn *smtpc = &conn->proto.smtpc;
  const char *path = data->state.path;
  char localhost[HOSTNAME_MAX + 1];

  /* Calculate the path if necessary */
  if(!*path) {
    if(!Curl_gethostname(localhost, sizeof(localhost)))
      path = localhost;
    else
      path = "localhost";
  }

  /* URL decode the path and use it as the domain in our EHLO */
  return Curl_urldecode(conn->data, path, 0, &smtpc->domain, NULL, TRUE);
}

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

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

  return result;
}

CURLcode Curl_smtp_escape_eob(struct connectdata *conn, const ssize_t nread)
{
  /* When sending a SMTP payload we must detect CRLF. sequences making sure
     they are sent as CRLF.. instead, as a . on the beginning of a line will
     be deleted by the server when not part of an EOB terminator and a
     genuine CRLF.CRLF which isn't escaped will wrongly be detected as end of
     data by the server
  */
  ssize_t i;
  ssize_t si;
  struct SessionHandle *data = conn->data;
  struct SMTP *smtp = data->req.protop;
  char *scratch = data->state.scratch;
  char *newscratch = NULL;
  char *oldscratch = NULL;
  size_t eob_sent;

  /* Do we need to allocate a scratch buffer? */
  if(!scratch || data->set.crlf) {
    oldscratch = scratch;

    scratch = newscratch = malloc(2 * BUFSIZE);
    if(!newscratch) {
      failf(data, "Failed to alloc scratch buffer!");

      return CURLE_OUT_OF_MEMORY;
    }
  }

  /* Have we already sent part of the EOB? */
  eob_sent = smtp->eob;

  /* This loop can be improved by some kind of Boyer-Moore style of
     approach but that is saved for later... */
  for(i = 0, si = 0; i < nread; i++) {
    if(SMTP_EOB[smtp->eob] == data->req.upload_fromhere[i]) {
      smtp->eob++;

      /* Is the EOB potentially the terminating CRLF? */
      if(2 == smtp->eob || SMTP_EOB_LEN == smtp->eob)
        smtp->trailing_crlf = TRUE;
      else
        smtp->trailing_crlf = FALSE;
    }
    else if(smtp->eob) {
      /* A previous substring matched so output that first */
      memcpy(&scratch[si], &SMTP_EOB[eob_sent], smtp->eob - eob_sent);
      si += smtp->eob - eob_sent;

      /* Then compare the first byte */
      if(SMTP_EOB[0] == data->req.upload_fromhere[i])
        smtp->eob = 1;
      else
        smtp->eob = 0;

      eob_sent = 0;

      /* Reset the trailing CRLF flag as there was more data */
      smtp->trailing_crlf = FALSE;
    }

    /* Do we have a match for CRLF. as per RFC-5321, sect. 4.5.2 */
    if(SMTP_EOB_FIND_LEN == smtp->eob) {
      /* Copy the replacement data to the target buffer */
      memcpy(&scratch[si], &SMTP_EOB_REPL[eob_sent],
             SMTP_EOB_REPL_LEN - eob_sent);
      si += SMTP_EOB_REPL_LEN - eob_sent;
      smtp->eob = 0;
      eob_sent = 0;
    }
    else if(!smtp->eob)
      scratch[si++] = data->req.upload_fromhere[i];
  }

  if(smtp->eob - eob_sent) {
    /* A substring matched before processing ended so output that now */
    memcpy(&scratch[si], &SMTP_EOB[eob_sent], smtp->eob - eob_sent);
    si += smtp->eob - eob_sent;
  }

  /* Only use the new buffer if we replaced something */
  if(si != nread) {
    /* Upload from the new (replaced) buffer instead */
    data->req.upload_fromhere = scratch;

    /* Save the buffer so it can be freed later */
    data->state.scratch = scratch;

    /* Free the old scratch buffer */
    Curl_safefree(oldscratch);

    /* Set the new amount too */
    data->req.upload_present = si;
  }
  else
    Curl_safefree(newscratch);

  return CURLE_OK;
}

#endif /* CURL_DISABLE_SMTP */