citadel/modules/smtp/serv_smtp.c

   1 /*
   2  * This module is an SMTP and ESMTP server for the Citadel system.
   3  * It is compliant with all of the following:
   4  *
   5  * RFC  821 - Simple Mail Transfer Protocol
   6  * RFC  876 - Survey of SMTP Implementations
   7  * RFC 1047 - Duplicate messages and SMTP
   8  * RFC 1652 - 8 bit MIME
   9  * RFC 1869 - Extended Simple Mail Transfer Protocol
  10  * RFC 1870 - SMTP Service Extension for Message Size Declaration
  11  * RFC 2033 - Local Mail Transfer Protocol
  12  * RFC 2197 - SMTP Service Extension for Command Pipelining
  13  * RFC 2476 - Message Submission
  14  * RFC 2487 - SMTP Service Extension for Secure SMTP over TLS
  15  * RFC 2554 - SMTP Service Extension for Authentication
  16  * RFC 2821 - Simple Mail Transfer Protocol
  17  * RFC 2822 - Internet Message Format
  18  * RFC 2920 - SMTP Service Extension for Command Pipelining
  19  *
  20  * The VRFY and EXPN commands have been removed from this implementation
  21  * because nobody uses these commands anymore, except for spammers.
  22  *
  23  * Copyright (c) 1998-2013 by the citadel.org team
  24  *
  25  * This program is open source software; you can redistribute it and/or modify
  26  * it under the terms of the GNU General Public License version 3.
  27  *
  28  * This program is distributed in the hope that it will be useful,
  29  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  30  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  31  * GNU General Public License for more details.
  32  */
  33
  34 #include "sysdep.h"
  35 #include <stdlib.h>
  36 #include <unistd.h>
  37 #include <stdio.h>
  38 #include <termios.h>
  39 #include <fcntl.h>
  40 #include <signal.h>
  41 #include <pwd.h>
  42 #include <errno.h>
  43 #include <sys/types.h>
  44 #include <syslog.h>
  45
  46 #if TIME_WITH_SYS_TIME
  47 # include <sys/time.h>
  48 # include <time.h>
  49 #else
  50 # if HAVE_SYS_TIME_H
  51 #  include <sys/time.h>
  52 # else
  53 #  include <time.h>
  54 # endif
  55 #endif
  56
  57 #include <sys/wait.h>
  58 #include <ctype.h>
  59 #include <string.h>
  60 #include <limits.h>
  61 #include <sys/socket.h>
  62 #include <netinet/in.h>
  63 #include <arpa/inet.h>
  64 #include <libcitadel.h>
  65 #include "citadel.h"
  66 #include "server.h"
  67 #include "citserver.h"
  68 #include "support.h"
  69 #include "config.h"
  70 #include "control.h"
  71 #include "user_ops.h"
  72 #include "room_ops.h"
  73 #include "database.h"
  74 #include "msgbase.h"
  75 #include "internet_addressing.h"
  76 #include "genstamp.h"
  77 #include "domain.h"
  78 #include "clientsocket.h"
  79 #include "locate_host.h"
  80 #include "citadel_dirs.h"
  81 #include "ctdl_module.h"
  82
  83 #include "smtp_util.h"
  84 enum {                          /* Command states for login authentication */
  85         smtp_command,
  86         smtp_user,
  87         smtp_password,
  88         smtp_plain
  89 };
  90
  91 enum SMTP_FLAGS {
  92         HELO,
  93         EHLO,
  94         LHLO
  95 };
  96
  97 typedef void (*smtp_handler)(long offest, long Flags);
  98
  99 typedef struct _smtp_handler_hook {
 100         smtp_handler h;
 101         int Flags;
 102 } smtp_handler_hook;
 103
 104 HashList *SMTPCmds = NULL;
 105 #define MaxSMTPCmdLen 10
 106
 107 #define RegisterSmtpCMD(First, H, Flags) \
 108         registerSmtpCMD(HKEY(First), H, Flags)
 109 void registerSmtpCMD(const char *First, long FLen,
 110                      smtp_handler H,
 111                      int Flags)
 112 {
 113         smtp_handler_hook *h;
 114
 115         if (FLen >= MaxSMTPCmdLen)
 116                 cit_panic_backtrace (0);
 117
 118         h = (smtp_handler_hook*) malloc(sizeof(smtp_handler_hook));
 119         memset(h, 0, sizeof(smtp_handler_hook));
 120
 121         h->Flags = Flags;
 122         h->h = H;
 123         Put(SMTPCmds, First, FLen, h, NULL);
 124 }
 125
 126 void smtp_cleanup(void)
 127 {
 128         DeleteHash(&SMTPCmds);
 129 }
 130
 131 /*
 132  * Here's where our SMTP session begins its happy day.
 133  */
 134 void smtp_greeting(int is_msa)
 135 {
 136         citsmtp *sSMTP;
 137         char message_to_spammer[1024];
 138
 139         strcpy(CC->cs_clientname, "SMTP session");
 140         CC->internal_pgm = 1;
 141         CC->cs_flags |= CS_STEALTH;
 142         CC->session_specific_data = malloc(sizeof(citsmtp));
 143         memset(SMTP, 0, sizeof(citsmtp));
 144         sSMTP = SMTP;
 145         sSMTP->is_msa = is_msa;
 146         sSMTP->Cmd = NewStrBufPlain(NULL, SIZ);
 147         sSMTP->helo_node = NewStrBuf();
 148         sSMTP->from = NewStrBufPlain(NULL, SIZ);
 149         sSMTP->recipients = NewStrBufPlain(NULL, SIZ);
 150         sSMTP->OneRcpt = NewStrBufPlain(NULL, SIZ);
 151         sSMTP->preferred_sender_email = NULL;
 152         sSMTP->preferred_sender_name = NULL;
 153
 154         /* If this config option is set, reject connections from problem
 155          * addresses immediately instead of after they execute a RCPT
 156          */
 157         if ( (config.c_rbl_at_greeting) && (sSMTP->is_msa == 0) ) {
 158                 if (rbl_check(message_to_spammer)) {
 159                         if (server_shutting_down)
 160                                 cprintf("421 %s\r\n", message_to_spammer);
 161                         else
 162                                 cprintf("550 %s\r\n", message_to_spammer);
 163                         CC->kill_me = KILLME_SPAMMER;
 164                         /* no need to free_recipients(valid), it's not allocated yet */
 165                         return;
 166                 }
 167         }
 168
 169         /* Otherwise we're either clean or we check later. */
 170
 171         if (CC->nologin==1) {
 172                 cprintf("451 Too many connections are already open; please try again later.\r\n");
 173                 CC->kill_me = KILLME_MAX_SESSIONS_EXCEEDED;
 174                 /* no need to free_recipients(valid), it's not allocated yet */
 175                 return;
 176         }
 177
 178         /* Note: the FQDN *must* appear as the first thing after the 220 code.
 179          * Some clients (including citmail.c) depend on it being there.
 180          */
 181         cprintf("220 %s ESMTP Citadel server ready.\r\n", config.c_fqdn);
 182 }
 183
 184
 185 /*
 186  * SMTPS is just like SMTP, except it goes crypto right away.
 187  */
 188 void smtps_greeting(void) {
 189         CtdlModuleStartCryptoMsgs(NULL, NULL, NULL);
 190 #ifdef HAVE_OPENSSL
 191         if (!CC->redirect_ssl) CC->kill_me = KILLME_NO_CRYPTO;          /* kill session if no crypto */
 192 #endif
 193         smtp_greeting(0);
 194 }
 195
 196
 197 /*
 198  * SMTP MSA port requires authentication.
 199  */
 200 void smtp_msa_greeting(void) {
 201         smtp_greeting(1);
 202 }
 203
 204
 205 /*
 206  * LMTP is like SMTP but with some extra bonus footage added.
 207  */
 208 void lmtp_greeting(void) {
 209
 210         smtp_greeting(0);
 211         SMTP->is_lmtp = 1;
 212 }
 213
 214
 215 /*
 216  * Generic SMTP MTA greeting
 217  */
 218 void smtp_mta_greeting(void) {
 219         smtp_greeting(0);
 220 }
 221
 222
 223 /*
 224  * We also have an unfiltered LMTP socket that bypasses spam filters.
 225  */
 226 void lmtp_unfiltered_greeting(void) {
 227         citsmtp *sSMTP;
 228
 229         smtp_greeting(0);
 230         sSMTP = SMTP;
 231         sSMTP->is_lmtp = 1;
 232         sSMTP->is_unfiltered = 1;
 233 }
 234
 235
 236 /*
 237  * Login greeting common to all auth methods
 238  */
 239 void smtp_auth_greeting(long offset, long Flags) {
 240         cprintf("235 Hello, %s\r\n", CC->user.fullname);
 241         syslog(LOG_NOTICE, "SMTP authenticated %s\n", CC->user.fullname);
 242         CC->internal_pgm = 0;
 243         CC->cs_flags &= ~CS_STEALTH;
 244 }
 245
 246
 247 /*
 248  * Implement HELO and EHLO commands.
 249  *
 250  * which_command:  0=HELO, 1=EHLO, 2=LHLO
 251  */
 252 void smtp_hello(long offset, long which_command)
 253 {
 254         citsmtp *sSMTP = SMTP;
 255
 256         StrBufAppendBuf (sSMTP->helo_node, sSMTP->Cmd, offset);
 257
 258         if ( (which_command != LHLO) && (sSMTP->is_lmtp) ) {
 259                 cprintf("500 Only LHLO is allowed when running LMTP\r\n");
 260                 return;
 261         }
 262
 263         if ( (which_command == LHLO) && (sSMTP->is_lmtp == 0) ) {
 264                 cprintf("500 LHLO is only allowed when running LMTP\r\n");
 265                 return;
 266         }
 267
 268         if (which_command == HELO) {
 269                 cprintf("250 Hello %s (%s [%s])\r\n",
 270                         ChrPtr(sSMTP->helo_node),
 271                         CC->cs_host,
 272                         CC->cs_addr
 273                 );
 274         }
 275         else {
 276                 if (which_command == EHLO) {
 277                         cprintf("250-Hello %s (%s [%s])\r\n",
 278                                 ChrPtr(sSMTP->helo_node),
 279                                 CC->cs_host,
 280                                 CC->cs_addr
 281                         );
 282                 }
 283                 else {
 284                         cprintf("250-Greetings and joyous salutations.\r\n");
 285                 }
 286                 cprintf("250-HELP\r\n");
 287                 cprintf("250-SIZE %ld\r\n", config.c_maxmsglen);
 288
 289 #ifdef HAVE_OPENSSL
 290                 /*
 291                  * Offer TLS, but only if TLS is not already active.
 292                  * Furthermore, only offer TLS when running on
 293                  * the SMTP-MSA port, not on the SMTP-MTA port, due to
 294                  * questionable reliability of TLS in certain sending MTA's.
 295                  */
 296                 if ( (!CC->redirect_ssl) && (sSMTP->is_msa) ) {
 297                         cprintf("250-STARTTLS\r\n");
 298                 }
 299 #endif  /* HAVE_OPENSSL */
 300
 301                 cprintf("250-AUTH LOGIN PLAIN\r\n"
 302                         "250-AUTH=LOGIN PLAIN\r\n"
 303                         "250 8BITMIME\r\n"
 304                 );
 305         }
 306 }
 307
 308
 309 /*
 310  * Backend function for smtp_webcit_preferences_hack().
 311  * Look at a message and determine if it's the preferences file.
 312  */
 313 void smtp_webcit_preferences_hack_backend(long msgnum, void *userdata) {
 314         struct CtdlMessage *msg;
 315         char **webcit_conf = (char **) userdata;
 316
 317         if (*webcit_conf) {
 318                 return; // already got it
 319         }
 320
 321         msg = CtdlFetchMessage(msgnum, 1);
 322         if (msg == NULL) {
 323                 return;
 324         }
 325
 326         if ( !CM_IsEmpty(msg, eMsgSubject) &&
 327              (!strcasecmp(msg->cm_fields[eMsgSubject], "__ WebCit Preferences __")))
 328         {
 329                 /* This is it!  Change ownership of the message text so it doesn't get freed. */
 330                 *webcit_conf = (char *)msg->cm_fields[eMesageText];
 331                 msg->cm_fields[eMesageText] = NULL;
 332         }
 333         CM_Free(msg);
 334 }
 335
 336
 337 /*
 338  * The configuration item for the user's preferred display name for outgoing email is, unfortunately,
 339  * stored in the account's WebCit configuration.  We have to fetch it now.
 340  */
 341 void smtp_webcit_preferences_hack(void) {
 342         char config_roomname[ROOMNAMELEN];
 343         char *webcit_conf = NULL;
 344         citsmtp *sSMTP = SMTP;
 345
 346         snprintf(config_roomname, sizeof config_roomname, "%010ld.%s", CC->user.usernum, USERCONFIGROOM);
 347         if (CtdlGetRoom(&CC->room, config_roomname) != 0) {
 348                 return;
 349         }
 350
 351         /*
 352          * Find the WebCit configuration message
 353          */
 354
 355         CtdlForEachMessage(MSGS_ALL, 1, NULL, NULL, NULL, smtp_webcit_preferences_hack_backend, (void *)&webcit_conf);
 356
 357         if (!webcit_conf) {
 358                 return;
 359         }
 360
 361         /* Parse the webcit configuration and attempt to do something useful with it */
 362         char *str = webcit_conf;
 363         char *saveptr = str;
 364         char *this_line = NULL;
 365         while (this_line = strtok_r(str, "\n", &saveptr), this_line != NULL) {
 366                 str = NULL;
 367                 if (!strncasecmp(this_line, "defaultfrom|", 12)) {
 368                         sSMTP->preferred_sender_email = NewStrBufPlain(&this_line[12], -1);
 369                 }
 370                 if (!strncasecmp(this_line, "defaultname|", 12)) {
 371                         sSMTP->preferred_sender_name = NewStrBufPlain(&this_line[12], -1);
 372                 }
 373                 if ((!strncasecmp(this_line, "defaultname|", 12)) && (sSMTP->preferred_sender_name == NULL)) {
 374                         sSMTP->preferred_sender_name = NewStrBufPlain(&this_line[12], -1);
 375                 }
 376
 377         }
 378         free(webcit_conf);
 379 }
 380
 381
 382
 383 /*
 384  * Implement HELP command.
 385  */
 386 void smtp_help(long offset, long Flags) {
 387         cprintf("214 RTFM http://www.ietf.org/rfc/rfc2821.txt\r\n");
 388 }
 389
 390
 391 /*
 392  *
 393  */
 394 void smtp_get_user(long offset)
 395 {
 396         char buf[SIZ];
 397         char username[SIZ];
 398         citsmtp *sSMTP = SMTP;
 399
 400         CtdlDecodeBase64(username, ChrPtr(sSMTP->Cmd) + offset, SIZ);
 401         /* syslog(LOG_DEBUG, "Trying <%s>\n", username); */
 402         if (CtdlLoginExistingUser(NULL, username) == login_ok) {
 403                 CtdlEncodeBase64(buf, "Password:", 9, 0);
 404                 cprintf("334 %s\r\n", buf);
 405                 sSMTP->command_state = smtp_password;
 406         }
 407         else {
 408                 cprintf("500 No such user.\r\n");
 409                 sSMTP->command_state = smtp_command;
 410         }
 411 }
 412
 413
 414 /*
 415  *
 416  */
 417 void smtp_get_pass(long offset, long Flags)
 418 {
 419         citsmtp *sSMTP = SMTP;
 420         char password[SIZ];
 421         long len;
 422
 423         memset(password, 0, sizeof(password));
 424         len = CtdlDecodeBase64(password, ChrPtr(sSMTP->Cmd), SIZ);
 425         /* syslog(LOG_DEBUG, "Trying <%s>\n", password); */
 426         if (CtdlTryPassword(password, len) == pass_ok) {
 427                 smtp_auth_greeting(offset, Flags);
 428         }
 429         else {
 430                 cprintf("535 Authentication failed.\r\n");
 431         }
 432         sSMTP->command_state = smtp_command;
 433 }
 434
 435
 436 /*
 437  * Back end for PLAIN auth method (either inline or multistate)
 438  */
 439 void smtp_try_plain(long offset, long Flags)
 440 {
 441         citsmtp *sSMTP = SMTP;
 442         const char*decoded_authstring;
 443         char ident[256] = "";
 444         char user[256] = "";
 445         char pass[256] = "";
 446         int result;
 447
 448         long decoded_len;
 449         long len;
 450
 451         memset(pass, 0, sizeof(pass));
 452         decoded_len = StrBufDecodeBase64(sSMTP->Cmd);
 453
 454         if (decoded_len > 0)
 455         {
 456                 decoded_authstring = ChrPtr(sSMTP->Cmd);
 457
 458                 len = safestrncpy(ident, decoded_authstring, sizeof ident);
 459
 460                 decoded_len -= len - 1;
 461                 decoded_authstring += len + 1;
 462
 463                 if (decoded_len > 0)
 464                 {
 465                         len = safestrncpy(user, decoded_authstring, sizeof user);
 466
 467                         decoded_authstring += len + 1;
 468                         decoded_len -= len - 1;
 469                 }
 470
 471                 if (decoded_len > 0)
 472                 {
 473                         len = safestrncpy(pass, decoded_authstring, sizeof pass);
 474
 475                         if (len < 0)
 476                                 len = sizeof(pass) - 1;
 477                 }
 478         }
 479
 480         sSMTP->command_state = smtp_command;
 481
 482         if (!IsEmptyStr(ident)) {
 483                 result = CtdlLoginExistingUser(user, ident);
 484         }
 485         else {
 486                 result = CtdlLoginExistingUser(NULL, user);
 487         }
 488
 489         if (result == login_ok) {
 490                 if (CtdlTryPassword(pass, len) == pass_ok) {
 491                         smtp_webcit_preferences_hack();
 492                         smtp_auth_greeting(offset, Flags);
 493                         return;
 494                 }
 495         }
 496         cprintf("504 Authentication failed.\r\n");
 497 }
 498
 499
 500 /*
 501  * Attempt to perform authenticated SMTP
 502  */
 503 void smtp_auth(long offset, long Flags)
 504 {
 505         citsmtp *sSMTP = SMTP;
 506         char username_prompt[64];
 507         char method[64];
 508         char encoded_authstring[1024];
 509
 510         if (CC->logged_in) {
 511                 cprintf("504 Already logged in.\r\n");
 512                 return;
 513         }
 514
 515         extract_token(method, ChrPtr(sSMTP->Cmd) + offset, 0, ' ', sizeof method);
 516
 517         if (!strncasecmp(method, "login", 5) ) {
 518                 if (StrLength(sSMTP->Cmd) - offset >= 7) {
 519                         smtp_get_user(6);
 520                 }
 521                 else {
 522                         CtdlEncodeBase64(username_prompt, "Username:", 9, 0);
 523                         cprintf("334 %s\r\n", username_prompt);
 524                         sSMTP->command_state = smtp_user;
 525                 }
 526                 return;
 527         }
 528
 529         if (!strncasecmp(method, "plain", 5) ) {
 530                 long len;
 531                 if (num_tokens(ChrPtr(sSMTP->Cmd) + offset, ' ') < 2) {
 532                         cprintf("334 \r\n");
 533                         SMTP->command_state = smtp_plain;
 534                         return;
 535                 }
 536
 537                 len = extract_token(encoded_authstring,
 538                                     ChrPtr(sSMTP->Cmd) + offset,
 539                                     1, ' ',
 540                                     sizeof encoded_authstring);
 541                 StrBufPlain(sSMTP->Cmd, encoded_authstring, len);
 542                 smtp_try_plain(0, Flags);
 543                 return;
 544         }
 545
 546         if (strncasecmp(method, "login", 5) ) {
 547                 cprintf("504 Unknown authentication method.\r\n");
 548                 return;
 549         }
 550
 551 }
 552
 553
 554 /*
 555  * Implements the RSET (reset state) command.
 556  * Currently this just zeroes out the state buffer.  If pointers to data
 557  * allocated with malloc() are ever placed in the state buffer, we have to
 558  * be sure to free() them first!
 559  *
 560  * Set do_response to nonzero to output the SMTP RSET response code.
 561  */
 562 void smtp_rset(long offset, long do_response) {
 563         citsmtp *sSMTP = SMTP;
 564
 565         /*
 566          * Our entire SMTP state is discarded when a RSET command is issued,
 567          * but we need to preserve this one little piece of information, so
 568          * we save it for later.
 569          */
 570
 571         FlushStrBuf(sSMTP->Cmd);
 572         FlushStrBuf(sSMTP->helo_node);
 573         FlushStrBuf(sSMTP->from);
 574         FlushStrBuf(sSMTP->recipients);
 575         FlushStrBuf(sSMTP->OneRcpt);
 576
 577         sSMTP->command_state = 0;
 578         sSMTP->number_of_recipients = 0;
 579         sSMTP->delivery_mode = 0;
 580         sSMTP->message_originated_locally = 0;
 581         sSMTP->is_msa = 0;
 582         /*
 583          * we must remember is_lmtp & is_unfiltered.
 584          */
 585
 586         /*
 587          * It is somewhat ambiguous whether we want to log out when a RSET
 588          * command is issued.  Here's the code to do it.  It is commented out
 589          * because some clients (such as Pine) issue RSET commands before
 590          * each message, but still expect to be logged in.
 591          *
 592          * if (CC->logged_in) {
 593          *      logout(CC);
 594          * }
 595          */
 596
 597         if (do_response) {
 598                 cprintf("250 Zap!\r\n");
 599         }
 600 }
 601
 602 /*
 603  * Clear out the portions of the state buffer that need to be cleared out
 604  * after the DATA command finishes.
 605  */
 606 void smtp_data_clear(long offset, long flags)
 607 {
 608         citsmtp *sSMTP = SMTP;
 609
 610         FlushStrBuf(sSMTP->from);
 611         FlushStrBuf(sSMTP->recipients);
 612         FlushStrBuf(sSMTP->OneRcpt);
 613         sSMTP->number_of_recipients = 0;
 614         sSMTP->delivery_mode = 0;
 615         sSMTP->message_originated_locally = 0;
 616 }
 617
 618 /*
 619  * Implements the "MAIL FROM:" command
 620  */
 621 void smtp_mail(long offset, long flags) {
 622         char user[SIZ];
 623         char node[SIZ];
 624         char name[SIZ];
 625         citsmtp *sSMTP = SMTP;
 626
 627         if (StrLength(sSMTP->from) > 0) {
 628                 cprintf("503 Only one sender permitted\r\n");
 629                 return;
 630         }
 631
 632         if (strncasecmp(ChrPtr(sSMTP->Cmd) + offset, "From:", 5)) {
 633                 cprintf("501 Syntax error\r\n");
 634                 return;
 635         }
 636
 637         StrBufAppendBuf(sSMTP->from, sSMTP->Cmd, offset);
 638         StrBufTrim(sSMTP->from);
 639         if (strchr(ChrPtr(sSMTP->from), '<') != NULL) {
 640                 StrBufStripAllBut(sSMTP->from, '<', '>');
 641         }
 642
 643         /* We used to reject empty sender names, until it was brought to our
 644          * attention that RFC1123 5.2.9 requires that this be allowed.  So now
 645          * we allow it, but replace the empty string with a fake
 646          * address so we don't have to contend with the empty string causing
 647          * other code to fail when it's expecting something there.
 648          */
 649         if (StrLength(sSMTP->from) == 0) {
 650                 StrBufPlain(sSMTP->from, HKEY("someone@example.com"));
 651         }
 652
 653         /* If this SMTP connection is from a logged-in user, force the 'from'
 654          * to be the user's Internet e-mail address as Citadel knows it.
 655          */
 656         if (CC->logged_in) {
 657                 StrBufPlain(sSMTP->from, CC->cs_inet_email, -1);
 658                 cprintf("250 Sender ok <%s>\r\n", ChrPtr(sSMTP->from));
 659                 sSMTP->message_originated_locally = 1;
 660                 return;
 661         }
 662
 663         else if (sSMTP->is_lmtp) {
 664                 /* Bypass forgery checking for LMTP */
 665         }
 666
 667         /* Otherwise, make sure outsiders aren't trying to forge mail from
 668          * this system (unless, of course, c_allow_spoofing is enabled)
 669          */
 670         else if (config.c_allow_spoofing == 0) {
 671                 process_rfc822_addr(ChrPtr(sSMTP->from), user, node, name);
 672                 syslog(LOG_DEBUG, "Claimed envelope sender is '%s' == '%s' @ '%s' ('%s')",
 673                         ChrPtr(sSMTP->from), user, node, name
 674                 );
 675                 if (CtdlHostAlias(node) != hostalias_nomatch) {
 676                         cprintf("550 You must log in to send mail from %s\r\n", node);
 677                         FlushStrBuf(sSMTP->from);
 678                         syslog(LOG_DEBUG, "Rejecting unauthenticated mail from %s", node);
 679                         return;
 680                 }
 681         }
 682
 683         cprintf("250 Sender ok\r\n");
 684 }
 685
 686
 687
 688 /*
 689  * Implements the "RCPT To:" command
 690  */
 691 void smtp_rcpt(long offset, long flags)
 692 {
 693         struct CitContext *CCC = CC;
 694         char message_to_spammer[SIZ];
 695         recptypes *valid = NULL;
 696         citsmtp *sSMTP = SMTP;
 697
 698         if (StrLength(sSMTP->from) == 0) {
 699                 cprintf("503 Need MAIL before RCPT\r\n");
 700                 return;
 701         }
 702
 703         if (strncasecmp(ChrPtr(sSMTP->Cmd) + offset, "To:", 3)) {
 704                 cprintf("501 Syntax error\r\n");
 705                 return;
 706         }
 707
 708         if ( (sSMTP->is_msa) && (!CCC->logged_in) ) {
 709                 cprintf("550 You must log in to send mail on this port.\r\n");
 710                 FlushStrBuf(sSMTP->from);
 711                 return;
 712         }
 713         FlushStrBuf(sSMTP->OneRcpt);
 714         StrBufAppendBuf(sSMTP->OneRcpt, sSMTP->Cmd, offset + 3);
 715         StrBufTrim(sSMTP->OneRcpt);
 716         StrBufStripAllBut(sSMTP->OneRcpt, '<', '>');
 717
 718         if ( (StrLength(sSMTP->OneRcpt) + StrLength(sSMTP->recipients)) >= SIZ) {
 719                 cprintf("452 Too many recipients\r\n");
 720                 return;
 721         }
 722
 723         /* RBL check */
 724         if ( (!CCC->logged_in)  /* Don't RBL authenticated users */
 725            && (!sSMTP->is_lmtp) ) {     /* Don't RBL LMTP clients */
 726                 if (config.c_rbl_at_greeting == 0) {    /* Don't RBL again if we already did it */
 727                         if (rbl_check(message_to_spammer)) {
 728                                 if (server_shutting_down)
 729                                         cprintf("421 %s\r\n", message_to_spammer);
 730                                 else
 731                                         cprintf("550 %s\r\n", message_to_spammer);
 732                                 /* no need to free_recipients(valid), it's not allocated yet */
 733                                 return;
 734                         }
 735                 }
 736         }
 737
 738         valid = validate_recipients(
 739                 ChrPtr(sSMTP->OneRcpt),
 740                 smtp_get_Recipients(),
 741                 (sSMTP->is_lmtp)? POST_LMTP: (CCC->logged_in)? POST_LOGGED_IN: POST_EXTERNAL
 742         );
 743         if (valid->num_error != 0) {
 744                 cprintf("550 %s\r\n", valid->errormsg);
 745                 free_recipients(valid);
 746                 return;
 747         }
 748
 749         if (valid->num_internet > 0) {
 750                 if (CCC->logged_in) {
 751                         if (CtdlCheckInternetMailPermission(&CCC->user)==0) {
 752                                 cprintf("551 <%s> - you do not have permission to send Internet mail\r\n",
 753                                         ChrPtr(sSMTP->OneRcpt));
 754                                 free_recipients(valid);
 755                                 return;
 756                         }
 757                 }
 758         }
 759
 760         if (valid->num_internet > 0) {
 761                 if ( (sSMTP->message_originated_locally == 0)
 762                    && (sSMTP->is_lmtp == 0) ) {
 763                         cprintf("551 <%s> - relaying denied\r\n", ChrPtr(sSMTP->OneRcpt));
 764                         free_recipients(valid);
 765                         return;
 766                 }
 767         }
 768
 769         cprintf("250 RCPT ok <%s>\r\n", ChrPtr(sSMTP->OneRcpt));
 770         if (StrLength(sSMTP->recipients) > 0) {
 771                 StrBufAppendBufPlain(sSMTP->recipients, HKEY(","), 0);
 772         }
 773         StrBufAppendBuf(sSMTP->recipients, sSMTP->OneRcpt, 0);
 774         sSMTP->number_of_recipients ++;
 775         if (valid != NULL)  {
 776                 free_recipients(valid);
 777         }
 778 }
 779
 780
 781
 782
 783 /*
 784  * Implements the DATA command
 785  */
 786 void smtp_data(long offset, long flags)
 787 {
 788         struct CitContext *CCC = CC;
 789         StrBuf *body;
 790         StrBuf *defbody;
 791         struct CtdlMessage *msg = NULL;
 792         long msgnum = (-1L);
 793         char nowstamp[SIZ];
 794         recptypes *valid;
 795         int scan_errors;
 796         int i;
 797         citsmtp *sSMTP = SMTP;
 798
 799         if (StrLength(sSMTP->from) == 0) {
 800                 cprintf("503 Need MAIL command first.\r\n");
 801                 return;
 802         }
 803
 804         if (sSMTP->number_of_recipients < 1) {
 805                 cprintf("503 Need RCPT command first.\r\n");
 806                 return;
 807         }
 808
 809         cprintf("354 Transmit message now - terminate with '.' by itself\r\n");
 810
 811         datestring(nowstamp, sizeof nowstamp, time(NULL), DATESTRING_RFC822);
 812         defbody = NewStrBufPlain(NULL, SIZ);
 813
 814         if (defbody != NULL) {
 815                 if (sSMTP->is_lmtp && (CCC->cs_UDSclientUID != -1)) {
 816                         StrBufPrintf(
 817                                 defbody,
 818                                 "Received: from %s (Citadel from userid %ld)\n"
 819                                 "       by %s; %s\n",
 820                                 ChrPtr(sSMTP->helo_node),
 821                                 (long int) CCC->cs_UDSclientUID,
 822                                 config.c_fqdn,
 823                                 nowstamp);
 824                 }
 825                 else {
 826                         StrBufPrintf(
 827                                 defbody,
 828                                 "Received: from %s (%s [%s])\n"
 829                                 "       by %s; %s\n",
 830                                 ChrPtr(sSMTP->helo_node),
 831                                 CCC->cs_host,
 832                                 CCC->cs_addr,
 833                                 config.c_fqdn,
 834                                 nowstamp);
 835                 }
 836         }
 837         body = CtdlReadMessageBodyBuf(HKEY("."), config.c_maxmsglen, defbody, 1, NULL);
 838         FreeStrBuf(&defbody);
 839         if (body == NULL) {
 840                 cprintf("550 Unable to save message: internal error.\r\n");
 841                 return;
 842         }
 843
 844         syslog(LOG_DEBUG, "Converting message...\n");
 845         msg = convert_internet_message_buf(&body);
 846
 847         /* If the user is locally authenticated, FORCE the From: header to
 848          * show up as the real sender.  Yes, this violates the RFC standard,
 849          * but IT MAKES SENSE.  If you prefer strict RFC adherence over
 850          * common sense, you can disable this in the configuration.
 851          *
 852          * We also set the "message room name" ('O' field) to MAILROOM
 853          * (which is Mail> on most systems) to prevent it from getting set
 854          * to something ugly like "0000058008.Sent Items>" when the message
 855          * is read with a Citadel client.
 856          */
 857         if ( (CCC->logged_in) && (config.c_rfc822_strict_from != CFG_SMTP_FROM_NOFILTER) ) {
 858                 int validemail = 0;
 859
 860                 if (!CM_IsEmpty(msg, erFc822Addr)       &&
 861                     ((config.c_rfc822_strict_from == CFG_SMTP_FROM_CORRECT) ||
 862                      (config.c_rfc822_strict_from == CFG_SMTP_FROM_REJECT)    )  )
 863                 {
 864                         if (!IsEmptyStr(CCC->cs_inet_email))
 865                                 validemail = strcmp(CCC->cs_inet_email, msg->cm_fields[erFc822Addr]) == 0;
 866                         if ((!validemail) &&
 867                             (!IsEmptyStr(CCC->cs_inet_other_emails)))
 868                         {
 869                                 int num_secondary_emails = 0;
 870                                 int i;
 871                                 num_secondary_emails = num_tokens(CCC->cs_inet_other_emails, '|');
 872                                 for (i=0; i < num_secondary_emails && !validemail; ++i) {
 873                                         char buf[256];
 874                                         extract_token(buf, CCC->cs_inet_other_emails,i,'|',sizeof CCC->cs_inet_other_emails);
 875                                         validemail = strcmp(buf, msg->cm_fields[erFc822Addr]) == 0;
 876                                 }
 877                         }
 878                 }
 879
 880                 if (!validemail && (config.c_rfc822_strict_from == CFG_SMTP_FROM_REJECT)) {
 881                         syslog(LOG_ERR, "invalid sender '%s' - rejecting this message", msg->cm_fields[erFc822Addr]);
 882                         cprintf("550 Invalid sender '%s' - rejecting this message.\r\n", msg->cm_fields[erFc822Addr]);
 883                         return;
 884                 }
 885
 886                 CM_SetField(msg, eNodeName, CFG_KEY(c_nodename));
 887                 CM_SetField(msg, eHumanNode, CFG_KEY(c_humannode));
 888                 CM_SetField(msg, eOriginalRoom, HKEY(MAILROOM));
 889                 if (sSMTP->preferred_sender_name != NULL)
 890                         CM_SetField(msg, eAuthor, SKEY(sSMTP->preferred_sender_name));
 891                 else
 892                         CM_SetField(msg, eAuthor, CCC->user.fullname, strlen(CCC->user.fullname));
 893
 894                 if (!validemail) {
 895                         if (sSMTP->preferred_sender_email != NULL)
 896                                 CM_SetField(msg, erFc822Addr, SKEY(sSMTP->preferred_sender_email));
 897                         else
 898                                 CM_SetField(msg, erFc822Addr, CCC->cs_inet_email, strlen(CCC->cs_inet_email));
 899                 }
 900         }
 901
 902         /* Set the "envelope from" address */
 903         CM_SetField(msg, eMessagePath, SKEY(sSMTP->from));
 904
 905         /* Set the "envelope to" address */
 906         CM_SetField(msg, eenVelopeTo, SKEY(sSMTP->recipients));
 907
 908         /* Submit the message into the Citadel system. */
 909         valid = validate_recipients(
 910                 ChrPtr(sSMTP->recipients),
 911                 smtp_get_Recipients(),
 912                 (sSMTP->is_lmtp)? POST_LMTP: (CCC->logged_in)? POST_LOGGED_IN: POST_EXTERNAL
 913         );
 914
 915         /* If there are modules that want to scan this message before final
 916          * submission (such as virus checkers or spam filters), call them now
 917          * and give them an opportunity to reject the message.
 918          */
 919         if (sSMTP->is_unfiltered) {
 920                 scan_errors = 0;
 921         }
 922         else {
 923                 scan_errors = PerformMessageHooks(msg, valid, EVT_SMTPSCAN);
 924         }
 925
 926         if (scan_errors > 0) {  /* We don't want this message! */
 927
 928                 if (CM_IsEmpty(msg, eErrorMsg)) {
 929                         CM_SetField(msg, eErrorMsg, HKEY("Message rejected by filter"));
 930                 }
 931
 932                 StrBufPrintf(sSMTP->OneRcpt, "550 %s\r\n", msg->cm_fields[eErrorMsg]);
 933         }
 934
 935         else {                  /* Ok, we'll accept this message. */
 936                 msgnum = CtdlSubmitMsg(msg, valid, "", 0);
 937                 if (msgnum > 0L) {
 938                         StrBufPrintf(sSMTP->OneRcpt, "250 Message accepted.\r\n");
 939                 }
 940                 else {
 941                         StrBufPrintf(sSMTP->OneRcpt, "550 Internal delivery error\r\n");
 942                 }
 943         }
 944
 945         /* For SMTP and ESMTP, just print the result message.  For LMTP, we
 946          * have to print one result message for each recipient.  Since there
 947          * is nothing in Citadel which would cause different recipients to
 948          * have different results, we can get away with just spitting out the
 949          * same message once for each recipient.
 950          */
 951         if (sSMTP->is_lmtp) {
 952                 for (i=0; i<sSMTP->number_of_recipients; ++i) {
 953                         cputbuf(sSMTP->OneRcpt);
 954                 }
 955         }
 956         else {
 957                 cputbuf(sSMTP->OneRcpt);
 958         }
 959
 960         /* Write something to the syslog(which may or may not be where the
 961          * rest of the Citadel logs are going; some sysadmins want LOG_MAIL).
 962          */
 963         syslog((LOG_MAIL | LOG_INFO),
 964                "%ld: from=<%s>, nrcpts=%d, relay=%s [%s], stat=%s",
 965                msgnum,
 966                ChrPtr(sSMTP->from),
 967                sSMTP->number_of_recipients,
 968                CCC->cs_host,
 969                CCC->cs_addr,
 970                ChrPtr(sSMTP->OneRcpt)
 971         );
 972
 973         /* Clean up */
 974         CM_Free(msg);
 975         free_recipients(valid);
 976         smtp_data_clear(0, 0);  /* clear out the buffers now */
 977 }
 978
 979
 980 /*
 981  * implements the STARTTLS command
 982  */
 983 void smtp_starttls(long offset, long flags)
 984 {
 985         char ok_response[SIZ];
 986         char nosup_response[SIZ];
 987         char error_response[SIZ];
 988
 989         sprintf(ok_response, "220 Begin TLS negotiation now\r\n");
 990         sprintf(nosup_response, "554 TLS not supported here\r\n");
 991         sprintf(error_response, "554 Internal error\r\n");
 992         CtdlModuleStartCryptoMsgs(ok_response, nosup_response, error_response);
 993         smtp_rset(0, 0);
 994 }
 995
 996
 997 /*
 998  * Main command loop for SMTP server sessions.
 999  */
1000 void smtp_command_loop(void)
1001 {
1002         struct CitContext *CCC = CC;
1003         citsmtp *sSMTP = SMTP;
1004         const char *pch, *pchs;
1005         long i;
1006         char CMD[MaxSMTPCmdLen + 1];
1007
1008         if (sSMTP == NULL) {
1009                 syslog(LOG_EMERG, "Session SMTP data is null.  WTF?  We will crash now.\n");
1010                 return cit_panic_backtrace (0);
1011         }
1012
1013         time(&CCC->lastcmd);
1014         if (CtdlClientGetLine(sSMTP->Cmd) < 1) {
1015                 syslog(LOG_CRIT, "SMTP: client disconnected: ending session.\n");
1016                 CC->kill_me = KILLME_CLIENT_DISCONNECTED;
1017                 return;
1018         }
1019         syslog(LOG_DEBUG, "SMTP server: %s\n", ChrPtr(sSMTP->Cmd));
1020
1021         if (sSMTP->command_state == smtp_user) {
1022                 smtp_get_user(0);
1023                 return;
1024         }
1025
1026         else if (sSMTP->command_state == smtp_password) {
1027                 smtp_get_pass(0, 0);
1028                 return;
1029         }
1030
1031         else if (sSMTP->command_state == smtp_plain) {
1032                 smtp_try_plain(0, 0);
1033                 return;
1034         }
1035
1036         pchs = pch = ChrPtr(sSMTP->Cmd);
1037         i = 0;
1038         while ((*pch != '\0') &&
1039                (!isblank(*pch)) &&
1040                (pch - pchs <= MaxSMTPCmdLen))
1041         {
1042                 CMD[i] = toupper(*pch);
1043                 pch ++;
1044                 i++;
1045         }
1046         CMD[i] = '\0';
1047
1048         if ((*pch == '\0') ||
1049             (isblank(*pch)))
1050         {
1051                 void *v;
1052
1053                 if (GetHash(SMTPCmds, CMD, i, &v) &&
1054                     (v != NULL))
1055                 {
1056                         smtp_handler_hook *h = (smtp_handler_hook*) v;
1057
1058                         if (isblank(pchs[i]))
1059                                 i++;
1060
1061                         h->h(i, h->Flags);
1062
1063                         return;
1064                 }
1065         }
1066         cprintf("502 I'm afraid I can't do that.\r\n");
1067 }
1068
1069 void smtp_noop(long offest, long Flags)
1070 {
1071         cprintf("250 NOOP\r\n");
1072 }
1073
1074 void smtp_quit(long offest, long Flags)
1075 {
1076         cprintf("221 Goodbye...\r\n");
1077         CC->kill_me = KILLME_CLIENT_LOGGED_OUT;
1078 }
1079
1080 /*****************************************************************************/
1081 /*                      MODULE INITIALIZATION STUFF                          */
1082 /*****************************************************************************/
1083 /*
1084  * This cleanup function blows away the temporary memory used by
1085  * the SMTP server.
1086  */
1087 void smtp_cleanup_function(void)
1088 {
1089         citsmtp *sSMTP = SMTP;
1090
1091         /* Don't do this stuff if this is not an SMTP session! */
1092         if (CC->h_command_function != smtp_command_loop) return;
1093
1094         syslog(LOG_DEBUG, "Performing SMTP cleanup hook\n");
1095
1096         FreeStrBuf(&sSMTP->Cmd);
1097         FreeStrBuf(&sSMTP->helo_node);
1098         FreeStrBuf(&sSMTP->from);
1099         FreeStrBuf(&sSMTP->recipients);
1100         FreeStrBuf(&sSMTP->OneRcpt);
1101         FreeStrBuf(&sSMTP->preferred_sender_email);
1102         FreeStrBuf(&sSMTP->preferred_sender_name);
1103
1104         free(sSMTP);
1105 }
1106
1107 const char *CitadelServiceSMTP_MTA="SMTP-MTA";
1108 const char *CitadelServiceSMTPS_MTA="SMTPs-MTA";
1109 const char *CitadelServiceSMTP_MSA="SMTP-MSA";
1110 const char *CitadelServiceSMTP_LMTP="LMTP";
1111 const char *CitadelServiceSMTP_LMTP_UNF="LMTP-UnF";
1112
1113 CTDL_MODULE_INIT(smtp)
1114 {
1115         if (!threading)
1116         {
1117                 SMTPCmds = NewHash(1, NULL);
1118
1119                 RegisterSmtpCMD("AUTH", smtp_auth, 0);
1120                 RegisterSmtpCMD("DATA", smtp_data, 0);
1121                 RegisterSmtpCMD("HELO", smtp_hello, HELO);
1122                 RegisterSmtpCMD("EHLO", smtp_hello, EHLO);
1123                 RegisterSmtpCMD("LHLO", smtp_hello, LHLO);
1124                 RegisterSmtpCMD("HELP", smtp_help, 0);
1125                 RegisterSmtpCMD("MAIL", smtp_mail, 0);
1126                 RegisterSmtpCMD("NOOP", smtp_noop, 0);
1127                 RegisterSmtpCMD("QUIT", smtp_quit, 0);
1128                 RegisterSmtpCMD("RCPT", smtp_rcpt, 0);
1129                 RegisterSmtpCMD("RSET", smtp_rset, 1);
1130 #ifdef HAVE_OPENSSL
1131                 RegisterSmtpCMD("STARTTLS", smtp_starttls, 0);
1132 #endif
1133
1134
1135                 CtdlRegisterServiceHook(config.c_smtp_port,     /* SMTP MTA */
1136                                         NULL,
1137                                         smtp_mta_greeting,
1138                                         smtp_command_loop,
1139                                         NULL,
1140                                         CitadelServiceSMTP_MTA);
1141
1142 #ifdef HAVE_OPENSSL
1143                 CtdlRegisterServiceHook(config.c_smtps_port,
1144                                         NULL,
1145                                         smtps_greeting,
1146                                         smtp_command_loop,
1147                                         NULL,
1148                                         CitadelServiceSMTPS_MTA);
1149 #endif
1150
1151                 CtdlRegisterServiceHook(config.c_msa_port,      /* SMTP MSA */
1152                                         NULL,
1153                                         smtp_msa_greeting,
1154                                         smtp_command_loop,
1155                                         NULL,
1156                                         CitadelServiceSMTP_MSA);
1157
1158                 CtdlRegisterServiceHook(0,                      /* local LMTP */
1159                                         file_lmtp_socket,
1160                                         lmtp_greeting,
1161                                         smtp_command_loop,
1162                                         NULL,
1163                                         CitadelServiceSMTP_LMTP);
1164
1165                 CtdlRegisterServiceHook(0,                      /* local LMTP */
1166                                         file_lmtp_unfiltered_socket,
1167                                         lmtp_unfiltered_greeting,
1168                                         smtp_command_loop,
1169                                         NULL,
1170                                         CitadelServiceSMTP_LMTP_UNF);
1171
1172                 CtdlRegisterCleanupHook(smtp_cleanup);
1173                 CtdlRegisterSessionHook(smtp_cleanup_function, EVT_STOP, PRIO_STOP + 250);
1174         }
1175
1176         /* return our module name for the log */
1177         return "smtp";
1178 }