src/common/smtp.c

   1 /*
   2  * Claws Mail -- a GTK based, lightweight, and fast e-mail client
   3  * Copyright (C) 1999-2022 the Claws Mail team and Hiroyuki Yamamoto
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 3 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  17  *
  18  */
  19
  20 #ifdef HAVE_CONFIG_H
  21 #  include "config.h"
  22 #include "claws-features.h"
  23 #endif
  24
  25 #include <glib.h>
  26 #ifdef ENABLE_NLS
  27 #include <glib/gi18n.h>
  28 #else
  29 #define _(a) (a)
  30 #define N_(a) (a)
  31 #endif
  32 #include <stdio.h>
  33 #include <string.h>
  34
  35 #include "smtp.h"
  36 #include "md5.h"
  37 #include "utils.h"
  38 #include "log.h"
  39
  40 static void smtp_session_destroy(Session *session);
  41
  42 static gint smtp_auth(SMTPSession *session);
  43 #ifdef USE_GNUTLS
  44 static gint smtp_starttls(SMTPSession *session);
  45 #endif
  46 #ifdef USE_OAUTH2
  47 static gint smtp_auth_oauth2(SMTPSession *session);
  48 #endif
  49 static gint smtp_auth_cram_md5(SMTPSession *session);
  50 static gint smtp_auth_login(SMTPSession *session);
  51 static gint smtp_auth_plain(SMTPSession *session);
  52
  53 static gint smtp_ehlo(SMTPSession *session);
  54 static gint smtp_ehlo_recv(SMTPSession *session, const gchar *msg);
  55
  56 static gint smtp_helo(SMTPSession *session);
  57 static gint smtp_rcpt(SMTPSession *session);
  58 static gint smtp_data(SMTPSession *session);
  59 static gint smtp_send_data(SMTPSession *session);
  60 static gint smtp_make_ready(SMTPSession *session);
  61 static gint smtp_eom(SMTPSession *session);
  62
  63 static gint smtp_session_recv_msg(Session *session, const gchar *msg);
  64 static gint smtp_session_send_data_finished(Session *session, guint len);
  65
  66
  67 Session *smtp_session_new(void *prefs_account)
  68 {
  69         SMTPSession *session;
  70
  71         session = g_new0(SMTPSession, 1);
  72
  73         session_init(SESSION(session), prefs_account, TRUE);
  74
  75         SESSION(session)->type             = SESSION_SMTP;
  76
  77         SESSION(session)->recv_msg         = smtp_session_recv_msg;
  78
  79         SESSION(session)->recv_data_finished = NULL;
  80         SESSION(session)->send_data_finished = smtp_session_send_data_finished;
  81
  82         SESSION(session)->destroy          = smtp_session_destroy;
  83
  84         session->state                     = SMTP_READY;
  85
  86 #ifdef USE_GNUTLS
  87         session->tls_init_done             = FALSE;
  88 #endif
  89
  90         session->hostname                  = NULL;
  91         session->user                      = NULL;
  92         session->pass                      = NULL;
  93
  94         session->from                      = NULL;
  95         session->to_list                   = NULL;
  96         session->cur_to                    = NULL;
  97
  98         session->send_data                 = NULL;
  99         session->send_data_len             = 0;
 100
 101         session->max_message_size          = -1;
 102
 103         session->avail_auth_type           = 0;
 104         session->forced_auth_type          = 0;
 105         session->auth_type                 = 0;
 106         session->esmtp_flags               = 0;
 107
 108         session->error_val                 = SM_OK;
 109         session->error_msg                 = NULL;
 110
 111         return SESSION(session);
 112 }
 113
 114 static void smtp_session_destroy(Session *session)
 115 {
 116         SMTPSession *smtp_session = SMTP_SESSION(session);
 117
 118         g_free(smtp_session->hostname);
 119         g_free(smtp_session->user);
 120         g_free(smtp_session->pass);
 121         g_free(smtp_session->from);
 122
 123         g_free(smtp_session->send_data);
 124
 125         g_free(smtp_session->error_msg);
 126 }
 127
 128 gint smtp_from(SMTPSession *session)
 129 {
 130         gchar buf[MESSAGEBUFSIZE];
 131         gchar *mail_size = NULL;
 132
 133         cm_return_val_if_fail(session->from != NULL, SM_ERROR);
 134
 135         session->state = SMTP_FROM;
 136
 137         if (session->is_esmtp && (session->esmtp_flags & ESMTP_SIZE)!=0)
 138                 mail_size = g_strdup_printf(" SIZE=%d", session->send_data_len);
 139         else
 140                 mail_size = g_strdup("");
 141
 142
 143         if (strchr(session->from, '<'))
 144                 g_snprintf(buf, sizeof(buf), "MAIL FROM:%s%s", session->from,
 145                            mail_size);
 146         else
 147                 g_snprintf(buf, sizeof(buf), "MAIL FROM:<%s>%s", session->from,
 148                            mail_size);
 149
 150         g_free(mail_size);
 151
 152         if (session_send_msg(SESSION(session), buf) < 0)
 153                 return SM_ERROR;
 154         log_print(LOG_PROTOCOL, "%sSMTP> %s\n", (session->is_esmtp?"E":""), buf);
 155
 156         return SM_OK;
 157 }
 158
 159 static gint smtp_auth(SMTPSession *session)
 160 {
 161
 162         cm_return_val_if_fail(session->user != NULL, SM_ERROR);
 163
 164         session->state = SMTP_AUTH;
 165
 166         if ((session->forced_auth_type == SMTPAUTH_CRAM_MD5
 167              || session->forced_auth_type == 0)
 168             &&
 169              (session->avail_auth_type & SMTPAUTH_CRAM_MD5) != 0)
 170                 smtp_auth_cram_md5(session);
 171         else if ((session->forced_auth_type == SMTPAUTH_LOGIN
 172                   || session->forced_auth_type == 0)
 173                  &&
 174                   (session->avail_auth_type & SMTPAUTH_LOGIN) != 0)
 175                 smtp_auth_login(session);
 176         else if ((session->forced_auth_type == SMTPAUTH_PLAIN
 177                   || session->forced_auth_type == 0)
 178                  &&
 179                   (session->avail_auth_type & SMTPAUTH_PLAIN) != 0)
 180                 smtp_auth_plain(session);
 181 #ifdef USE_OAUTH2
 182         else if ((session->forced_auth_type == SMTPAUTH_OAUTH2
 183                   || session->forced_auth_type == 0)
 184                  &&
 185                   (session->avail_auth_type & SMTPAUTH_OAUTH2) != 0)
 186                 smtp_auth_oauth2(session);
 187 #endif
 188         else if (session->forced_auth_type == 0) {
 189                 log_warning(LOG_PROTOCOL, _("No SMTP AUTH method available\n"));
 190                 return SM_AUTHFAIL;
 191         } else {
 192                 log_warning(LOG_PROTOCOL, _("Selected SMTP AUTH method not available\n"));
 193                 return SM_AUTHFAIL;
 194         }
 195
 196         return SM_OK;
 197 }
 198
 199 static gint smtp_auth_recv(SMTPSession *session, const gchar *msg)
 200 {
 201         gchar buf[MESSAGEBUFSIZE], *tmp;
 202
 203         switch (session->auth_type) {
 204         case SMTPAUTH_LOGIN:
 205                 session->state = SMTP_AUTH_LOGIN_USER;
 206
 207                 if (!strncmp(msg, "334 ", 4)) {
 208                         tmp = g_base64_encode(session->user, strlen(session->user));
 209
 210                         if (session_send_msg(SESSION(session), tmp) < 0) {
 211                                 g_free(tmp);
 212                                 return SM_ERROR;
 213                         }
 214                         g_free(tmp);
 215                         log_print(LOG_PROTOCOL, "ESMTP> [USERID]\n");
 216                 } else {
 217                         /* Server rejects AUTH */
 218                         if (session_send_msg(SESSION(session), "*") < 0)
 219                                 return SM_ERROR;
 220                         log_print(LOG_PROTOCOL, "ESMTP> *\n");
 221                 }
 222                 break;
 223         case SMTPAUTH_CRAM_MD5:
 224                 session->state = SMTP_AUTH_CRAM_MD5;
 225
 226                 if (!strncmp(msg, "334 ", 4)) {
 227                         gchar *response;
 228                         gchar *response64;
 229                         gchar *challenge;
 230                         gsize challengelen;
 231                         guchar hexdigest[33];
 232
 233                         challenge = g_base64_decode_zero(msg + 4, &challengelen);
 234                         log_print(LOG_PROTOCOL, "ESMTP< [Decoded: %s]\n", challenge);
 235
 236                         g_snprintf(buf, sizeof(buf), "%s", session->pass);
 237                         md5_hex_hmac(hexdigest, challenge, challengelen,
 238                                      buf, strlen(session->pass));
 239                         g_free(challenge);
 240
 241                         response = g_strdup_printf
 242                                 ("%s %s", session->user, hexdigest);
 243                         log_print(LOG_PROTOCOL, "ESMTP> [Encoded: %s]\n", response);
 244
 245                         response64 = g_base64_encode(response, strlen(response));
 246                         g_free(response);
 247
 248                         if (session_send_msg(SESSION(session), response64) < 0) {
 249                                 g_free(response64);
 250                                 return SM_ERROR;
 251                         }
 252                         log_print(LOG_PROTOCOL, "ESMTP> %s\n", response64);
 253                         g_free(response64);
 254                 } else {
 255                         /* Server rejects AUTH */
 256                         if (session_send_msg(SESSION(session), "*") < 0)
 257                                 return SM_ERROR;
 258                         log_print(LOG_PROTOCOL, "ESMTP> *\n");
 259                 }
 260                 break;
 261         case SMTPAUTH_DIGEST_MD5:
 262         default:
 263                 /* stop smtp_auth when no correct authtype */
 264                 if (session_send_msg(SESSION(session), "*") < 0)
 265                         return SM_ERROR;
 266                 log_print(LOG_PROTOCOL, "ESMTP> *\n");
 267                 break;
 268         }
 269
 270         return SM_OK;
 271 }
 272
 273 static gint smtp_auth_login_user_recv(SMTPSession *session, const gchar *msg)
 274 {
 275         gchar *tmp;
 276
 277         session->state = SMTP_AUTH_LOGIN_PASS;
 278
 279         if (!strncmp(msg, "334 ", 4)) {
 280                 tmp = g_base64_encode(session->pass, strlen(session->pass));
 281         } else {
 282                 /* Server rejects AUTH */
 283                 tmp = g_strdup("*");
 284         }
 285
 286         if (session_send_msg(SESSION(session), tmp) < 0) {
 287                 g_free(tmp);
 288                 return SM_ERROR;
 289         }
 290         g_free(tmp);
 291
 292         log_print(LOG_PROTOCOL, "ESMTP> [PASSWORD]\n");
 293
 294         return SM_OK;
 295 }
 296
 297 static gint smtp_ehlo(SMTPSession *session)
 298 {
 299         gchar buf[MESSAGEBUFSIZE];
 300
 301         session->state = SMTP_EHLO;
 302
 303         session->avail_auth_type = 0;
 304
 305         g_snprintf(buf, sizeof(buf), "EHLO %s",
 306                    session->hostname ? session->hostname : get_domain_name());
 307         if (session_send_msg(SESSION(session), buf) < 0)
 308                 return SM_ERROR;
 309         log_print(LOG_PROTOCOL, "ESMTP> %s\n", buf);
 310
 311         return SM_OK;
 312 }
 313
 314 static gint smtp_ehlo_recv(SMTPSession *session, const gchar *msg)
 315 {
 316         if (strncmp(msg, "250", 3) == 0) {
 317                 const gchar *p = msg;
 318                 p += 3;
 319                 if (*p == '-' || *p == ' ') p++;
 320                 if (g_ascii_strncasecmp(p, "AUTH", 4) == 0) {
 321                         p += 5;
 322                         if (strcasestr(p, "PLAIN"))
 323                                 session->avail_auth_type |= SMTPAUTH_PLAIN;
 324                         if (strcasestr(p, "LOGIN"))
 325                                 session->avail_auth_type |= SMTPAUTH_LOGIN;
 326                         if (strcasestr(p, "CRAM-MD5"))
 327                                 session->avail_auth_type |= SMTPAUTH_CRAM_MD5;
 328                         if (strcasestr(p, "DIGEST-MD5"))
 329                                 session->avail_auth_type |= SMTPAUTH_DIGEST_MD5;
 330 #ifdef USE_GNUTLS
 331                         if (strcasestr(p, "XOAUTH2"))
 332                                 session->avail_auth_type |= SMTPAUTH_OAUTH2;
 333 #endif
 334                 }
 335                 if (g_ascii_strncasecmp(p, "SIZE", 4) == 0) {
 336                         p += 5;
 337                         session->max_message_size = atoi(p);
 338                         session->esmtp_flags |= ESMTP_SIZE;
 339                 }
 340                 if (g_ascii_strncasecmp(p, "STARTTLS", 8) == 0) {
 341                         p += 9;
 342                         session->avail_auth_type |= SMTPAUTH_TLS_AVAILABLE;
 343                 }
 344                 return SM_OK;
 345         } else if ((msg[0] == '1' || msg[0] == '2' || msg[0] == '3') &&
 346             (msg[3] == ' ' || msg[3] == '\0'))
 347                 return SM_OK;
 348         else if (msg[0] == '5' && msg[1] == '0' &&
 349                  (msg[2] == '4' || msg[2] == '3' || msg[2] == '1'))
 350                 return SM_ERROR;
 351
 352         return SM_ERROR;
 353 }
 354
 355 #ifdef USE_GNUTLS
 356 static gint smtp_starttls(SMTPSession *session)
 357 {
 358         session->state = SMTP_STARTTLS;
 359
 360         if (session_send_msg(SESSION(session), "STARTTLS") < 0)
 361                 return SM_ERROR;
 362         log_print(LOG_PROTOCOL, "ESMTP> STARTTLS\n");
 363
 364         return SM_OK;
 365 }
 366 #endif
 367
 368 static gint smtp_auth_cram_md5(SMTPSession *session)
 369 {
 370         session->state = SMTP_AUTH;
 371         session->auth_type = SMTPAUTH_CRAM_MD5;
 372
 373         if (session_send_msg(SESSION(session), "AUTH CRAM-MD5") < 0)
 374                 return SM_ERROR;
 375         log_print(LOG_PROTOCOL, "ESMTP> AUTH CRAM-MD5\n");
 376
 377         return SM_OK;
 378 }
 379
 380 static gint smtp_auth_plain(SMTPSession *session)
 381 {
 382         gchar buf[MESSAGEBUFSIZE], *b64buf, *out;
 383         gint len;
 384
 385         session->state = SMTP_AUTH_PLAIN;
 386         session->auth_type = SMTPAUTH_PLAIN;
 387
 388         memset(buf, 0, sizeof buf);
 389
 390         /* "\0user\0password" */
 391         len = sprintf(buf, "%c%s%c%s", '\0', session->user, '\0', session->pass);
 392         b64buf = g_base64_encode(buf, len);
 393         out = g_strconcat("AUTH PLAIN ", b64buf, NULL);
 394         g_free(b64buf);
 395
 396         if (session_send_msg(SESSION(session), out) < 0) {
 397                 g_free(out);
 398                 return SM_ERROR;
 399         }
 400
 401         g_free(out);
 402
 403         log_print(LOG_PROTOCOL, "ESMTP> [AUTH PLAIN]\n");
 404
 405         return SM_OK;
 406 }
 407
 408 #ifdef USE_OAUTH2
 409 static gint smtp_auth_oauth2(SMTPSession *session)
 410 {
 411         gchar buf[MESSAGEBUFSIZE], *b64buf, *out;
 412         gint len;
 413
 414         session->state = SMTP_AUTH_OAUTH2;
 415         session->auth_type = SMTPAUTH_OAUTH2;
 416
 417         memset(buf, 0, sizeof buf);
 418
 419         /* "user=" {User} "^Aauth=Bearer " {Access Token} "^A^A"*/
 420         /* session->pass contains the OAUTH2 Access Token*/
 421         len = sprintf(buf, "user=%s\1auth=Bearer %s\1\1", session->user, session->pass);
 422         b64buf = g_base64_encode(buf, len);
 423         out = g_strconcat("AUTH XOAUTH2 ", b64buf, NULL);
 424         g_free(b64buf);
 425
 426         if (session_send_msg(SESSION(session), out) < 0) {
 427                 g_free(out);
 428                 return SM_ERROR;
 429         }
 430
 431         g_free(out);
 432
 433         log_print(LOG_PROTOCOL, "ESMTP> [AUTH XOAUTH2]\n");
 434
 435         return SM_OK;
 436 }
 437 #endif
 438
 439 static gint smtp_auth_login(SMTPSession *session)
 440 {
 441         session->state = SMTP_AUTH;
 442         session->auth_type = SMTPAUTH_LOGIN;
 443
 444         if (session_send_msg(SESSION(session), "AUTH LOGIN") < 0)
 445                 return SM_ERROR;
 446         log_print(LOG_PROTOCOL, "ESMTP> AUTH LOGIN\n");
 447
 448         return SM_OK;
 449 }
 450
 451 static gint smtp_helo(SMTPSession *session)
 452 {
 453         gchar buf[MESSAGEBUFSIZE];
 454
 455         session->state = SMTP_HELO;
 456
 457         g_snprintf(buf, sizeof(buf), "HELO %s",
 458                    session->hostname ? session->hostname : get_domain_name());
 459         if (session_send_msg(SESSION(session), buf) < 0)
 460                 return SM_ERROR;
 461         log_print(LOG_PROTOCOL, "SMTP> %s\n", buf);
 462
 463         return SM_OK;
 464 }
 465
 466 static gint smtp_rcpt(SMTPSession *session)
 467 {
 468         gchar buf[MESSAGEBUFSIZE];
 469         gchar *to;
 470
 471         cm_return_val_if_fail(session->cur_to != NULL, SM_ERROR);
 472
 473         session->state = SMTP_RCPT;
 474
 475         to = (gchar *)session->cur_to->data;
 476
 477         if (strchr(to, '<'))
 478                 g_snprintf(buf, sizeof(buf), "RCPT TO:%s", to);
 479         else
 480                 g_snprintf(buf, sizeof(buf), "RCPT TO:<%s>", to);
 481         if (session_send_msg(SESSION(session), buf) < 0)
 482                 return SM_ERROR;
 483         log_print(LOG_PROTOCOL, "SMTP> %s\n", buf);
 484
 485         session->cur_to = session->cur_to->next;
 486
 487         return SM_OK;
 488 }
 489
 490 static gint smtp_data(SMTPSession *session)
 491 {
 492         session->state = SMTP_DATA;
 493
 494         if (session_send_msg(SESSION(session), "DATA") < 0)
 495                 return SM_ERROR;
 496         log_print(LOG_PROTOCOL, "SMTP> DATA\n");
 497
 498         return SM_OK;
 499 }
 500
 501 static gint smtp_send_data(SMTPSession *session)
 502 {
 503         session->state = SMTP_SEND_DATA;
 504
 505         session_send_data(SESSION(session), session->send_data,
 506                           session->send_data_len);
 507
 508         return SM_OK;
 509 }
 510
 511 static gint smtp_make_ready(SMTPSession *session)
 512 {
 513         session->state = SMTP_MAIL_SENT_OK;
 514
 515         return SM_OK;
 516 }
 517
 518 gint smtp_quit(SMTPSession *session)
 519 {
 520         session->state = SMTP_QUIT;
 521
 522         session_send_msg(SESSION(session), "QUIT");
 523         log_print(LOG_PROTOCOL, "SMTP> QUIT\n");
 524
 525         return SM_OK;
 526 }
 527
 528 static gint smtp_eom(SMTPSession *session)
 529 {
 530         session->state = SMTP_EOM;
 531
 532         if (session_send_msg(SESSION(session), ".") < 0)
 533                 return SM_ERROR;
 534         log_print(LOG_PROTOCOL, "SMTP> . (EOM)\n");
 535
 536         return SM_OK;
 537 }
 538
 539 static gint smtp_session_recv_msg(Session *session, const gchar *msg)
 540 {
 541         SMTPSession *smtp_session = SMTP_SESSION(session);
 542         gboolean cont = FALSE;
 543         gint ret = 0;
 544
 545         if (strlen(msg) < 4) {
 546                 log_warning(LOG_PROTOCOL, _("bad SMTP response\n"));
 547                 return -1;
 548         }
 549
 550         switch (smtp_session->state) {
 551         case SMTP_EHLO:
 552         case SMTP_STARTTLS:
 553         case SMTP_AUTH:
 554         case SMTP_AUTH_PLAIN:
 555         case SMTP_AUTH_LOGIN_USER:
 556         case SMTP_AUTH_LOGIN_PASS:
 557 #ifdef USE_GNUTLS
 558         case SMTP_AUTH_OAUTH2:
 559 #endif
 560         case SMTP_AUTH_CRAM_MD5:
 561                 log_print(LOG_PROTOCOL, "ESMTP< %s\n", msg);
 562                 break;
 563         default:
 564                 log_print(LOG_PROTOCOL, "SMTP< %s\n", msg);
 565                 break;
 566         }
 567
 568         /* ignore all multiline responses except for EHLO */
 569         if (msg[3] == '-' && smtp_session->state != SMTP_EHLO)
 570                 return session_recv_msg(session);
 571
 572         if (msg[0] == '5' && msg[1] == '0' &&
 573             (msg[2] == '4' || msg[2] == '3' || msg[2] == '1')) {
 574                 log_warning(LOG_PROTOCOL, _("error occurred on SMTP session\n"));
 575                 smtp_session->state = SMTP_ERROR;
 576                 smtp_session->error_val = SM_ERROR;
 577                 g_free(smtp_session->error_msg);
 578                 smtp_session->error_msg = g_strdup(msg);
 579                 return -1;
 580         }
 581
 582         if (!strncmp(msg, "535", 3)) {
 583                 log_warning(LOG_PROTOCOL, _("error occurred on authentication\n"));
 584                 smtp_session->state = SMTP_ERROR;
 585                 smtp_session->error_val = SM_AUTHFAIL;
 586                 g_free(smtp_session->error_msg);
 587                 smtp_session->error_msg = g_strdup(msg);
 588                 return -1;
 589         }
 590
 591         if (msg[0] != '1' && msg[0] != '2' && msg[0] != '3') {
 592                 log_warning(LOG_PROTOCOL, _("error occurred on SMTP session\n"));
 593                 smtp_session->state = SMTP_ERROR;
 594                 smtp_session->error_val = SM_ERROR;
 595                 g_free(smtp_session->error_msg);
 596                 smtp_session->error_msg = g_strdup(msg);
 597                 return -1;
 598         }
 599
 600         if (msg[3] == '-')
 601                 cont = TRUE;
 602         else if (msg[3] != ' ' && msg[3] != '\0') {
 603                 log_warning(LOG_PROTOCOL, _("bad SMTP response\n"));
 604                 smtp_session->state = SMTP_ERROR;
 605                 smtp_session->error_val = SM_UNRECOVERABLE;
 606                 return -1;
 607         }
 608
 609         switch (smtp_session->state) {
 610         case SMTP_READY:
 611                 if (strstr(msg, "ESMTP"))
 612                         smtp_session->is_esmtp = TRUE;
 613 #ifdef USE_GNUTLS
 614                 if (smtp_session->user || session->ssl_type != SSL_NONE ||
 615                     smtp_session->is_esmtp)
 616 #else
 617                 if (smtp_session->user || smtp_session->is_esmtp)
 618 #endif
 619                         ret = smtp_ehlo(smtp_session);
 620                 else
 621                         ret = smtp_helo(smtp_session);
 622                 break;
 623         case SMTP_HELO:
 624                 ret = smtp_from(smtp_session);
 625                 break;
 626         case SMTP_EHLO:
 627                 ret = smtp_ehlo_recv(smtp_session, msg);
 628                 if (cont == TRUE)
 629                         break;
 630                 if (smtp_session->max_message_size > 0
 631                 && smtp_session->max_message_size <
 632                    smtp_session->send_data_len) {
 633                         log_warning(LOG_PROTOCOL, _("Message is too big "
 634                               "(Maximum size is %s)\n"),
 635                               to_human_readable(
 636                                (goffset)(smtp_session->max_message_size)));
 637                         smtp_session->state = SMTP_ERROR;
 638                         smtp_session->error_val = SM_ERROR;
 639                         return -1;
 640                 }
 641 #ifdef USE_GNUTLS
 642                 if (session->ssl_type == SSL_STARTTLS &&
 643                     smtp_session->tls_init_done == FALSE) {
 644                         ret = smtp_starttls(smtp_session);
 645                         break;
 646                 }
 647 #endif
 648                 if (smtp_session->user) {
 649                         if (smtp_auth(smtp_session) != SM_OK) {
 650 #ifdef USE_GNUTLS
 651                                 if (session->ssl_type == SSL_NONE
 652                                 &&  smtp_session->tls_init_done == FALSE
 653                                 &&  (smtp_session->avail_auth_type & SMTPAUTH_TLS_AVAILABLE))
 654                                         ret = smtp_starttls(smtp_session);
 655                                 else
 656 #endif
 657                                         ret = smtp_from(smtp_session);
 658                         }
 659                 } else
 660                         ret = smtp_from(smtp_session);
 661                 break;
 662         case SMTP_STARTTLS:
 663 #ifdef USE_GNUTLS
 664                 if (session_start_tls(session) < 0) {
 665                         log_warning(LOG_PROTOCOL, _("couldn't start STARTTLS session\n"));
 666                         smtp_session->state = SMTP_ERROR;
 667                         smtp_session->error_val = SM_ERROR;
 668                         return -1;
 669                 }
 670                 smtp_session->tls_init_done = TRUE;
 671                 ret = smtp_ehlo(smtp_session);
 672 #endif
 673                 break;
 674         case SMTP_AUTH:
 675                 ret = smtp_auth_recv(smtp_session, msg);
 676                 break;
 677         case SMTP_AUTH_LOGIN_USER:
 678                 ret = smtp_auth_login_user_recv(smtp_session, msg);
 679                 break;
 680         case SMTP_AUTH_PLAIN:
 681         case SMTP_AUTH_LOGIN_PASS:
 682 #ifdef USE_GNUTLS
 683         case SMTP_AUTH_OAUTH2:
 684 #endif
 685         case SMTP_AUTH_CRAM_MD5:
 686                 ret = smtp_from(smtp_session);
 687                 break;
 688         case SMTP_FROM:
 689                 if (smtp_session->cur_to)
 690                         ret = smtp_rcpt(smtp_session);
 691                 break;
 692         case SMTP_RCPT:
 693                 if (smtp_session->cur_to)
 694                         ret = smtp_rcpt(smtp_session);
 695                 else
 696                         ret = smtp_data(smtp_session);
 697                 break;
 698         case SMTP_DATA:
 699                 ret = smtp_send_data(smtp_session);
 700                 break;
 701         case SMTP_EOM:
 702                 smtp_make_ready(smtp_session);
 703                 break;
 704         case SMTP_QUIT:
 705                 session_disconnect(session);
 706                 break;
 707         case SMTP_ERROR:
 708         default:
 709                 log_warning(LOG_PROTOCOL, _("error occurred on SMTP session\n"));
 710                 smtp_session->error_val = SM_ERROR;
 711                 return -1;
 712         }
 713
 714         if (cont && ret == SM_OK)
 715                 return session_recv_msg(session);
 716
 717         if (ret != SM_OK)
 718                 smtp_session->error_val = SM_ERROR;
 719
 720         return ret == SM_OK ? 0 : -1;
 721 }
 722
 723 static gint smtp_session_send_data_finished(Session *session, guint len)
 724 {
 725         return smtp_eom(SMTP_SESSION(session));
 726 }