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         citsmtp *sSMTP = SMTP;
 398
 399         StrBufDecodeBase64(sSMTP->Cmd);
 400
 401         /* syslog(LOG_DEBUG, "Trying <%s>\n", username); */
 402         if (CtdlLoginExistingUser(NULL, ChrPtr(sSMTP->Cmd)) == login_ok) {
 403                 size_t len = CtdlEncodeBase64(buf, "Password:", 9, 0);
 404
 405                 if (buf[len - 1] == '\n') {
 406                         buf[len - 1] = '\0';
 407                 }
 408                 cprintf("334 %s\r\n", buf);
 409                 sSMTP->command_state = smtp_password;
 410         }
 411         else {
 412                 cprintf("500 No such user.\r\n");
 413                 sSMTP->command_state = smtp_command;
 414         }
 415 }
 416
 417
 418 /*
 419  *
 420  */
 421 void smtp_get_pass(long offset, long Flags)
 422 {
 423         citsmtp *sSMTP = SMTP;
 424         char password[SIZ];
 425
 426         memset(password, 0, sizeof(password));
 427         StrBufDecodeBase64(sSMTP->Cmd);
 428         /* syslog(LOG_DEBUG, "Trying <%s>\n", password); */
 429         if (CtdlTryPassword(SKEY(sSMTP->Cmd)) == pass_ok) {
 430                 smtp_auth_greeting(offset, Flags);
 431         }
 432         else {
 433                 cprintf("535 Authentication failed.\r\n");
 434         }
 435         sSMTP->command_state = smtp_command;
 436 }
 437
 438
 439 /*
 440  * Back end for PLAIN auth method (either inline or multistate)
 441  */
 442 void smtp_try_plain(long offset, long Flags)
 443 {
 444         citsmtp *sSMTP = SMTP;
 445         const char*decoded_authstring;
 446         char ident[256] = "";
 447         char user[256] = "";
 448         char pass[256] = "";
 449         int result;
 450
 451         long decoded_len;
 452         long len = 0;
 453         long plen = 0;
 454
 455         memset(pass, 0, sizeof(pass));
 456         decoded_len = StrBufDecodeBase64(sSMTP->Cmd);
 457
 458         if (decoded_len > 0)
 459         {
 460                 decoded_authstring = ChrPtr(sSMTP->Cmd);
 461
 462                 len = safestrncpy(ident, decoded_authstring, sizeof ident);
 463
 464                 decoded_len -= len - 1;
 465                 decoded_authstring += len + 1;
 466
 467                 if (decoded_len > 0)
 468                 {
 469                         len = safestrncpy(user, decoded_authstring, sizeof user);
 470
 471                         decoded_authstring += len + 1;
 472                         decoded_len -= len - 1;
 473                 }
 474
 475                 if (decoded_len > 0)
 476                 {
 477                         plen = safestrncpy(pass, decoded_authstring, sizeof pass);
 478
 479                         if (plen < 0)
 480                                 plen = sizeof(pass) - 1;
 481                 }
 482         }
 483
 484         sSMTP->command_state = smtp_command;
 485
 486         if (!IsEmptyStr(ident)) {
 487                 result = CtdlLoginExistingUser(user, ident);
 488         }
 489         else {
 490                 result = CtdlLoginExistingUser(NULL, user);
 491         }
 492
 493         if (result == login_ok) {
 494                 if (CtdlTryPassword(pass, plen) == pass_ok) {
 495                         smtp_webcit_preferences_hack();
 496                         smtp_auth_greeting(offset, Flags);
 497                         return;
 498                 }
 499         }
 500         cprintf("504 Authentication failed.\r\n");
 501 }
 502
 503
 504 /*
 505  * Attempt to perform authenticated SMTP
 506  */
 507 void smtp_auth(long offset, long Flags)
 508 {
 509         citsmtp *sSMTP = SMTP;
 510         char username_prompt[64];
 511         char method[64];
 512         char encoded_authstring[1024];
 513
 514         if (CC->logged_in) {
 515                 cprintf("504 Already logged in.\r\n");
 516                 return;
 517         }
 518
 519         extract_token(method, ChrPtr(sSMTP->Cmd) + offset, 0, ' ', sizeof method);
 520
 521         if (!strncasecmp(method, "login", 5) ) {
 522                 if (StrLength(sSMTP->Cmd) - offset >= 7) {
 523                         smtp_get_user(6);
 524                 }
 525                 else {
 526                         size_t len = CtdlEncodeBase64(username_prompt, "Username:", 9, 0);
 527                         if (username_prompt[len - 1] == '\n') {
 528                                 username_prompt[len - 1] = '\0';
 529                         }
 530                         cprintf("334 %s\r\n", username_prompt);
 531                         sSMTP->command_state = smtp_user;
 532                 }
 533                 return;
 534         }
 535
 536         if (!strncasecmp(method, "plain", 5) ) {
 537                 long len;
 538                 if (num_tokens(ChrPtr(sSMTP->Cmd) + offset, ' ') < 2) {
 539                         cprintf("334 \r\n");
 540                         SMTP->command_state = smtp_plain;
 541                         return;
 542                 }
 543
 544                 len = extract_token(encoded_authstring,
 545                                     ChrPtr(sSMTP->Cmd) + offset,
 546                                     1, ' ',
 547                                     sizeof encoded_authstring);
 548                 StrBufPlain(sSMTP->Cmd, encoded_authstring, len);
 549                 smtp_try_plain(0, Flags);
 550                 return;
 551         }
 552
 553         if (strncasecmp(method, "login", 5) ) {
 554                 cprintf("504 Unknown authentication method.\r\n");
 555                 return;
 556         }
 557
 558 }
 559
 560
 561 /*
 562  * Implements the RSET (reset state) command.
 563  * Currently this just zeroes out the state buffer.  If pointers to data
 564  * allocated with malloc() are ever placed in the state buffer, we have to
 565  * be sure to free() them first!
 566  *
 567  * Set do_response to nonzero to output the SMTP RSET response code.
 568  */
 569 void smtp_rset(long offset, long do_response) {
 570         citsmtp *sSMTP = SMTP;
 571
 572         /*
 573          * Our entire SMTP state is discarded when a RSET command is issued,
 574          * but we need to preserve this one little piece of information, so
 575          * we save it for later.
 576          */
 577
 578         FlushStrBuf(sSMTP->Cmd);
 579         FlushStrBuf(sSMTP->helo_node);
 580         FlushStrBuf(sSMTP->from);
 581         FlushStrBuf(sSMTP->recipients);
 582         FlushStrBuf(sSMTP->OneRcpt);
 583
 584         sSMTP->command_state = 0;
 585         sSMTP->number_of_recipients = 0;
 586         sSMTP->delivery_mode = 0;
 587         sSMTP->message_originated_locally = 0;
 588         sSMTP->is_msa = 0;
 589         /*
 590          * we must remember is_lmtp & is_unfiltered.
 591          */
 592
 593         /*
 594          * It is somewhat ambiguous whether we want to log out when a RSET
 595          * command is issued.  Here's the code to do it.  It is commented out
 596          * because some clients (such as Pine) issue RSET commands before
 597          * each message, but still expect to be logged in.
 598          *
 599          * if (CC->logged_in) {
 600          *      logout(CC);
 601          * }
 602          */
 603
 604         if (do_response) {
 605                 cprintf("250 Zap!\r\n");
 606         }
 607 }
 608
 609 /*
 610  * Clear out the portions of the state buffer that need to be cleared out
 611  * after the DATA command finishes.
 612  */
 613 void smtp_data_clear(long offset, long flags)
 614 {
 615         citsmtp *sSMTP = SMTP;
 616
 617         FlushStrBuf(sSMTP->from);
 618         FlushStrBuf(sSMTP->recipients);
 619         FlushStrBuf(sSMTP->OneRcpt);
 620         sSMTP->number_of_recipients = 0;
 621         sSMTP->delivery_mode = 0;
 622         sSMTP->message_originated_locally = 0;
 623 }
 624
 625 /*
 626  * Implements the "MAIL FROM:" command
 627  */
 628 void smtp_mail(long offset, long flags) {
 629         char user[SIZ];
 630         char node[SIZ];
 631         char name[SIZ];
 632         citsmtp *sSMTP = SMTP;
 633
 634         if (StrLength(sSMTP->from) > 0) {
 635                 cprintf("503 Only one sender permitted\r\n");
 636                 return;
 637         }
 638
 639         if (strncasecmp(ChrPtr(sSMTP->Cmd) + offset, "From:", 5)) {
 640                 cprintf("501 Syntax error\r\n");
 641                 return;
 642         }
 643
 644         StrBufAppendBuf(sSMTP->from, sSMTP->Cmd, offset);
 645         StrBufTrim(sSMTP->from);
 646         if (strchr(ChrPtr(sSMTP->from), '<') != NULL) {
 647                 StrBufStripAllBut(sSMTP->from, '<', '>');
 648         }
 649
 650         /* We used to reject empty sender names, until it was brought to our
 651          * attention that RFC1123 5.2.9 requires that this be allowed.  So now
 652          * we allow it, but replace the empty string with a fake
 653          * address so we don't have to contend with the empty string causing
 654          * other code to fail when it's expecting something there.
 655          */
 656         if (StrLength(sSMTP->from) == 0) {
 657                 StrBufPlain(sSMTP->from, HKEY("someone@example.com"));
 658         }
 659
 660         /* If this SMTP connection is from a logged-in user, force the 'from'
 661          * to be the user's Internet e-mail address as Citadel knows it.
 662          */
 663         if (CC->logged_in) {
 664                 StrBufPlain(sSMTP->from, CC->cs_inet_email, -1);
 665                 cprintf("250 Sender ok <%s>\r\n", ChrPtr(sSMTP->from));
 666                 sSMTP->message_originated_locally = 1;
 667                 return;
 668         }
 669
 670         else if (sSMTP->is_lmtp) {
 671                 /* Bypass forgery checking for LMTP */
 672         }
 673
 674         /* Otherwise, make sure outsiders aren't trying to forge mail from
 675          * this system (unless, of course, c_allow_spoofing is enabled)
 676          */
 677         else if (config.c_allow_spoofing == 0) {
 678                 process_rfc822_addr(ChrPtr(sSMTP->from), user, node, name);
 679                 syslog(LOG_DEBUG, "Claimed envelope sender is '%s' == '%s' @ '%s' ('%s')",
 680                         ChrPtr(sSMTP->from), user, node, name
 681                 );
 682                 if (CtdlHostAlias(node) != hostalias_nomatch) {
 683                         cprintf("550 You must log in to send mail from %s\r\n", node);
 684                         FlushStrBuf(sSMTP->from);
 685                         syslog(LOG_DEBUG, "Rejecting unauthenticated mail from %s", node);
 686                         return;
 687                 }
 688         }
 689
 690         cprintf("250 Sender ok\r\n");
 691 }
 692
 693
 694
 695 /*
 696  * Implements the "RCPT To:" command
 697  */
 698 void smtp_rcpt(long offset, long flags)
 699 {
 700         struct CitContext *CCC = CC;
 701         char message_to_spammer[SIZ];
 702         recptypes *valid = NULL;
 703         citsmtp *sSMTP = SMTP;
 704
 705         if (StrLength(sSMTP->from) == 0) {
 706                 cprintf("503 Need MAIL before RCPT\r\n");
 707                 return;
 708         }
 709
 710         if (strncasecmp(ChrPtr(sSMTP->Cmd) + offset, "To:", 3)) {
 711                 cprintf("501 Syntax error\r\n");
 712                 return;
 713         }
 714
 715         if ( (sSMTP->is_msa) && (!CCC->logged_in) ) {
 716                 cprintf("550 You must log in to send mail on this port.\r\n");
 717                 FlushStrBuf(sSMTP->from);
 718                 return;
 719         }
 720         FlushStrBuf(sSMTP->OneRcpt);
 721         StrBufAppendBuf(sSMTP->OneRcpt, sSMTP->Cmd, offset + 3);
 722         StrBufTrim(sSMTP->OneRcpt);
 723         StrBufStripAllBut(sSMTP->OneRcpt, '<', '>');
 724
 725         if ( (StrLength(sSMTP->OneRcpt) + StrLength(sSMTP->recipients)) >= SIZ) {
 726                 cprintf("452 Too many recipients\r\n");
 727                 return;
 728         }
 729
 730         /* RBL check */
 731         if ( (!CCC->logged_in)  /* Don't RBL authenticated users */
 732            && (!sSMTP->is_lmtp) ) {     /* Don't RBL LMTP clients */
 733                 if (config.c_rbl_at_greeting == 0) {    /* Don't RBL again if we already did it */
 734                         if (rbl_check(message_to_spammer)) {
 735                                 if (server_shutting_down)
 736                                         cprintf("421 %s\r\n", message_to_spammer);
 737                                 else
 738                                         cprintf("550 %s\r\n", message_to_spammer);
 739                                 /* no need to free_recipients(valid), it's not allocated yet */
 740                                 return;
 741                         }
 742                 }
 743         }
 744
 745         valid = validate_recipients(
 746                 ChrPtr(sSMTP->OneRcpt),
 747                 smtp_get_Recipients(),
 748                 (sSMTP->is_lmtp)? POST_LMTP: (CCC->logged_in)? POST_LOGGED_IN: POST_EXTERNAL
 749         );
 750         if (valid->num_error != 0) {
 751                 cprintf("550 %s\r\n", valid->errormsg);
 752                 free_recipients(valid);
 753                 return;
 754         }
 755
 756         if (valid->num_internet > 0) {
 757                 if (CCC->logged_in) {
 758                         if (CtdlCheckInternetMailPermission(&CCC->user)==0) {
 759                                 cprintf("551 <%s> - you do not have permission to send Internet mail\r\n",
 760                                         ChrPtr(sSMTP->OneRcpt));
 761                                 free_recipients(valid);
 762                                 return;
 763                         }
 764                 }
 765         }
 766
 767         if (valid->num_internet > 0) {
 768                 if ( (sSMTP->message_originated_locally == 0)
 769                    && (sSMTP->is_lmtp == 0) ) {
 770                         cprintf("551 <%s> - relaying denied\r\n", ChrPtr(sSMTP->OneRcpt));
 771                         free_recipients(valid);
 772                         return;
 773                 }
 774         }
 775
 776         cprintf("250 RCPT ok <%s>\r\n", ChrPtr(sSMTP->OneRcpt));
 777         if (StrLength(sSMTP->recipients) > 0) {
 778                 StrBufAppendBufPlain(sSMTP->recipients, HKEY(","), 0);
 779         }
 780         StrBufAppendBuf(sSMTP->recipients, sSMTP->OneRcpt, 0);
 781         sSMTP->number_of_recipients ++;
 782         if (valid != NULL)  {
 783                 free_recipients(valid);
 784         }
 785 }
 786
 787
 788
 789
 790 /*
 791  * Implements the DATA command
 792  */
 793 void smtp_data(long offset, long flags)
 794 {
 795         struct CitContext *CCC = CC;
 796         StrBuf *body;
 797         StrBuf *defbody;
 798         struct CtdlMessage *msg = NULL;
 799         long msgnum = (-1L);
 800         char nowstamp[SIZ];
 801         recptypes *valid;
 802         int scan_errors;
 803         int i;
 804         citsmtp *sSMTP = SMTP;
 805
 806         if (StrLength(sSMTP->from) == 0) {
 807                 cprintf("503 Need MAIL command first.\r\n");
 808                 return;
 809         }
 810
 811         if (sSMTP->number_of_recipients < 1) {
 812                 cprintf("503 Need RCPT command first.\r\n");
 813                 return;
 814         }
 815
 816         cprintf("354 Transmit message now - terminate with '.' by itself\r\n");
 817
 818         datestring(nowstamp, sizeof nowstamp, time(NULL), DATESTRING_RFC822);
 819         defbody = NewStrBufPlain(NULL, SIZ);
 820
 821         if (defbody != NULL) {
 822                 if (sSMTP->is_lmtp && (CCC->cs_UDSclientUID != -1)) {
 823                         StrBufPrintf(
 824                                 defbody,
 825                                 "Received: from %s (Citadel from userid %ld)\n"
 826                                 "       by %s; %s\n",
 827                                 ChrPtr(sSMTP->helo_node),
 828                                 (long int) CCC->cs_UDSclientUID,
 829                                 config.c_fqdn,
 830                                 nowstamp);
 831                 }
 832                 else {
 833                         StrBufPrintf(
 834                                 defbody,
 835                                 "Received: from %s (%s [%s])\n"
 836                                 "       by %s; %s\n",
 837                                 ChrPtr(sSMTP->helo_node),
 838                                 CCC->cs_host,
 839                                 CCC->cs_addr,
 840                                 config.c_fqdn,
 841                                 nowstamp);
 842                 }
 843         }
 844         body = CtdlReadMessageBodyBuf(HKEY("."), config.c_maxmsglen, defbody, 1, NULL);
 845         FreeStrBuf(&defbody);
 846         if (body == NULL) {
 847                 cprintf("550 Unable to save message: internal error.\r\n");
 848                 return;
 849         }
 850
 851         syslog(LOG_DEBUG, "Converting message...\n");
 852         msg = convert_internet_message_buf(&body);
 853
 854         /* If the user is locally authenticated, FORCE the From: header to
 855          * show up as the real sender.  Yes, this violates the RFC standard,
 856          * but IT MAKES SENSE.  If you prefer strict RFC adherence over
 857          * common sense, you can disable this in the configuration.
 858          *
 859          * We also set the "message room name" ('O' field) to MAILROOM
 860          * (which is Mail> on most systems) to prevent it from getting set
 861          * to something ugly like "0000058008.Sent Items>" when the message
 862          * is read with a Citadel client.
 863          */
 864         if ( (CCC->logged_in) && (config.c_rfc822_strict_from != CFG_SMTP_FROM_NOFILTER) ) {
 865                 int validemail = 0;
 866
 867                 if (!CM_IsEmpty(msg, erFc822Addr)       &&
 868                     ((config.c_rfc822_strict_from == CFG_SMTP_FROM_CORRECT) ||
 869                      (config.c_rfc822_strict_from == CFG_SMTP_FROM_REJECT)    )  )
 870                 {
 871                         if (!IsEmptyStr(CCC->cs_inet_email))
 872                                 validemail = strcmp(CCC->cs_inet_email, msg->cm_fields[erFc822Addr]) == 0;
 873                         if ((!validemail) &&
 874                             (!IsEmptyStr(CCC->cs_inet_other_emails)))
 875                         {
 876                                 int num_secondary_emails = 0;
 877                                 int i;
 878                                 num_secondary_emails = num_tokens(CCC->cs_inet_other_emails, '|');
 879                                 for (i=0; i < num_secondary_emails && !validemail; ++i) {
 880                                         char buf[256];
 881                                         extract_token(buf, CCC->cs_inet_other_emails,i,'|',sizeof CCC->cs_inet_other_emails);
 882                                         validemail = strcmp(buf, msg->cm_fields[erFc822Addr]) == 0;
 883                                 }
 884                         }
 885                 }
 886
 887                 if (!validemail && (config.c_rfc822_strict_from == CFG_SMTP_FROM_REJECT)) {
 888                         syslog(LOG_ERR, "invalid sender '%s' - rejecting this message", msg->cm_fields[erFc822Addr]);
 889                         cprintf("550 Invalid sender '%s' - rejecting this message.\r\n", msg->cm_fields[erFc822Addr]);
 890                         return;
 891                 }
 892
 893                 CM_SetField(msg, eNodeName, CFG_KEY(c_nodename));
 894                 CM_SetField(msg, eHumanNode, CFG_KEY(c_humannode));
 895                 CM_SetField(msg, eOriginalRoom, HKEY(MAILROOM));
 896                 if (sSMTP->preferred_sender_name != NULL)
 897                         CM_SetField(msg, eAuthor, SKEY(sSMTP->preferred_sender_name));
 898                 else
 899                         CM_SetField(msg, eAuthor, CCC->user.fullname, strlen(CCC->user.fullname));
 900
 901                 if (!validemail) {
 902                         if (sSMTP->preferred_sender_email != NULL)
 903                                 CM_SetField(msg, erFc822Addr, SKEY(sSMTP->preferred_sender_email));
 904                         else
 905                                 CM_SetField(msg, erFc822Addr, CCC->cs_inet_email, strlen(CCC->cs_inet_email));
 906                 }
 907         }
 908
 909         /* Set the "envelope from" address */
 910         CM_SetField(msg, eMessagePath, SKEY(sSMTP->from));
 911
 912         /* Set the "envelope to" address */
 913         CM_SetField(msg, eenVelopeTo, SKEY(sSMTP->recipients));
 914
 915         /* Submit the message into the Citadel system. */
 916         valid = validate_recipients(
 917                 ChrPtr(sSMTP->recipients),
 918                 smtp_get_Recipients(),
 919                 (sSMTP->is_lmtp)? POST_LMTP: (CCC->logged_in)? POST_LOGGED_IN: POST_EXTERNAL
 920         );
 921
 922         /* If there are modules that want to scan this message before final
 923          * submission (such as virus checkers or spam filters), call them now
 924          * and give them an opportunity to reject the message.
 925          */
 926         if (sSMTP->is_unfiltered) {
 927                 scan_errors = 0;
 928         }
 929         else {
 930                 scan_errors = PerformMessageHooks(msg, valid, EVT_SMTPSCAN);
 931         }
 932
 933         if (scan_errors > 0) {  /* We don't want this message! */
 934
 935                 if (CM_IsEmpty(msg, eErrorMsg)) {
 936                         CM_SetField(msg, eErrorMsg, HKEY("Message rejected by filter"));
 937                 }
 938
 939                 StrBufPrintf(sSMTP->OneRcpt, "550 %s\r\n", msg->cm_fields[eErrorMsg]);
 940         }
 941
 942         else {                  /* Ok, we'll accept this message. */
 943                 msgnum = CtdlSubmitMsg(msg, valid, "", 0);
 944                 if (msgnum > 0L) {
 945                         StrBufPrintf(sSMTP->OneRcpt, "250 Message accepted.\r\n");
 946                 }
 947                 else {
 948                         StrBufPrintf(sSMTP->OneRcpt, "550 Internal delivery error\r\n");
 949                 }
 950         }
 951
 952         /* For SMTP and ESMTP, just print the result message.  For LMTP, we
 953          * have to print one result message for each recipient.  Since there
 954          * is nothing in Citadel which would cause different recipients to
 955          * have different results, we can get away with just spitting out the
 956          * same message once for each recipient.
 957          */
 958         if (sSMTP->is_lmtp) {
 959                 for (i=0; i<sSMTP->number_of_recipients; ++i) {
 960                         cputbuf(sSMTP->OneRcpt);
 961                 }
 962         }
 963         else {
 964                 cputbuf(sSMTP->OneRcpt);
 965         }
 966
 967         /* Write something to the syslog(which may or may not be where the
 968          * rest of the Citadel logs are going; some sysadmins want LOG_MAIL).
 969          */
 970         syslog((LOG_MAIL | LOG_INFO),
 971                "%ld: from=<%s>, nrcpts=%d, relay=%s [%s], stat=%s",
 972                msgnum,
 973                ChrPtr(sSMTP->from),
 974                sSMTP->number_of_recipients,
 975                CCC->cs_host,
 976                CCC->cs_addr,
 977                ChrPtr(sSMTP->OneRcpt)
 978         );
 979
 980         /* Clean up */
 981         CM_Free(msg);
 982         free_recipients(valid);
 983         smtp_data_clear(0, 0);  /* clear out the buffers now */
 984 }
 985
 986
 987 /*
 988  * implements the STARTTLS command
 989  */
 990 void smtp_starttls(long offset, long flags)
 991 {
 992         char ok_response[SIZ];
 993         char nosup_response[SIZ];
 994         char error_response[SIZ];
 995
 996         sprintf(ok_response, "220 Begin TLS negotiation now\r\n");
 997         sprintf(nosup_response, "554 TLS not supported here\r\n");
 998         sprintf(error_response, "554 Internal error\r\n");
 999         CtdlModuleStartCryptoMsgs(ok_response, nosup_response, error_response);
1000         smtp_rset(0, 0);
1001 }
1002
1003
1004 /*
1005  * Main command loop for SMTP server sessions.
1006  */
1007 void smtp_command_loop(void)
1008 {
1009         static const ConstStr AuthPlainStr = {HKEY("AUTH PLAIN")};
1010         struct CitContext *CCC = CC;
1011         citsmtp *sSMTP = SMTP;
1012         const char *pch, *pchs;
1013         long i;
1014         char CMD[MaxSMTPCmdLen + 1];
1015
1016         if (sSMTP == NULL) {
1017                 syslog(LOG_EMERG, "Session SMTP data is null.  WTF?  We will crash now.\n");
1018                 return cit_panic_backtrace (0);
1019         }
1020
1021         time(&CCC->lastcmd);
1022         if (CtdlClientGetLine(sSMTP->Cmd) < 1) {
1023                 syslog(LOG_CRIT, "SMTP: client disconnected: ending session.\n");
1024                 CC->kill_me = KILLME_CLIENT_DISCONNECTED;
1025                 return;
1026         }
1027         syslog(LOG_DEBUG, "SMTP server: %s\n", ChrPtr(sSMTP->Cmd));
1028
1029         if (sSMTP->command_state == smtp_user) {
1030                 if (!strncmp(ChrPtr(sSMTP->Cmd), AuthPlainStr.Key, AuthPlainStr.len))
1031                         smtp_try_plain(0, 0);
1032                 else
1033                         smtp_get_user(0);
1034                 return;
1035         }
1036
1037         else if (sSMTP->command_state == smtp_password) {
1038                 smtp_get_pass(0, 0);
1039                 return;
1040         }
1041
1042         else if (sSMTP->command_state == smtp_plain) {
1043                 smtp_try_plain(0, 0);
1044                 return;
1045         }
1046
1047         pchs = pch = ChrPtr(sSMTP->Cmd);
1048         i = 0;
1049         while ((*pch != '\0') &&
1050                (!isblank(*pch)) &&
1051                (pch - pchs <= MaxSMTPCmdLen))
1052         {
1053                 CMD[i] = toupper(*pch);
1054                 pch ++;
1055                 i++;
1056         }
1057         CMD[i] = '\0';
1058
1059         if ((*pch == '\0') ||
1060             (isblank(*pch)))
1061         {
1062                 void *v;
1063
1064                 if (GetHash(SMTPCmds, CMD, i, &v) &&
1065                     (v != NULL))
1066                 {
1067                         smtp_handler_hook *h = (smtp_handler_hook*) v;
1068
1069                         if (isblank(pchs[i]))
1070                                 i++;
1071
1072                         h->h(i, h->Flags);
1073
1074                         return;
1075                 }
1076         }
1077         cprintf("502 I'm afraid I can't do that.\r\n");
1078 }
1079
1080 void smtp_noop(long offest, long Flags)
1081 {
1082         cprintf("250 NOOP\r\n");
1083 }
1084
1085 void smtp_quit(long offest, long Flags)
1086 {
1087         cprintf("221 Goodbye...\r\n");
1088         CC->kill_me = KILLME_CLIENT_LOGGED_OUT;
1089 }
1090
1091 /*****************************************************************************/
1092 /*                      MODULE INITIALIZATION STUFF                          */
1093 /*****************************************************************************/
1094 /*
1095  * This cleanup function blows away the temporary memory used by
1096  * the SMTP server.
1097  */
1098 void smtp_cleanup_function(void)
1099 {
1100         citsmtp *sSMTP = SMTP;
1101
1102         /* Don't do this stuff if this is not an SMTP session! */
1103         if (CC->h_command_function != smtp_command_loop) return;
1104
1105         syslog(LOG_DEBUG, "Performing SMTP cleanup hook\n");
1106
1107         FreeStrBuf(&sSMTP->Cmd);
1108         FreeStrBuf(&sSMTP->helo_node);
1109         FreeStrBuf(&sSMTP->from);
1110         FreeStrBuf(&sSMTP->recipients);
1111         FreeStrBuf(&sSMTP->OneRcpt);
1112         FreeStrBuf(&sSMTP->preferred_sender_email);
1113         FreeStrBuf(&sSMTP->preferred_sender_name);
1114
1115         free(sSMTP);
1116 }
1117
1118 const char *CitadelServiceSMTP_MTA="SMTP-MTA";
1119 const char *CitadelServiceSMTPS_MTA="SMTPs-MTA";
1120 const char *CitadelServiceSMTP_MSA="SMTP-MSA";
1121 const char *CitadelServiceSMTP_LMTP="LMTP";
1122 const char *CitadelServiceSMTP_LMTP_UNF="LMTP-UnF";
1123
1124 CTDL_MODULE_INIT(smtp)
1125 {
1126         if (!threading)
1127         {
1128                 SMTPCmds = NewHash(1, NULL);
1129
1130                 RegisterSmtpCMD("AUTH", smtp_auth, 0);
1131                 RegisterSmtpCMD("DATA", smtp_data, 0);
1132                 RegisterSmtpCMD("HELO", smtp_hello, HELO);
1133                 RegisterSmtpCMD("EHLO", smtp_hello, EHLO);
1134                 RegisterSmtpCMD("LHLO", smtp_hello, LHLO);
1135                 RegisterSmtpCMD("HELP", smtp_help, 0);
1136                 RegisterSmtpCMD("MAIL", smtp_mail, 0);
1137                 RegisterSmtpCMD("NOOP", smtp_noop, 0);
1138                 RegisterSmtpCMD("QUIT", smtp_quit, 0);
1139                 RegisterSmtpCMD("RCPT", smtp_rcpt, 0);
1140                 RegisterSmtpCMD("RSET", smtp_rset, 1);
1141 #ifdef HAVE_OPENSSL
1142                 RegisterSmtpCMD("STARTTLS", smtp_starttls, 0);
1143 #endif
1144
1145
1146                 CtdlRegisterServiceHook(config.c_smtp_port,     /* SMTP MTA */
1147                                         NULL,
1148                                         smtp_mta_greeting,
1149                                         smtp_command_loop,
1150                                         NULL,
1151                                         CitadelServiceSMTP_MTA);
1152
1153 #ifdef HAVE_OPENSSL
1154                 CtdlRegisterServiceHook(config.c_smtps_port,
1155                                         NULL,
1156                                         smtps_greeting,
1157                                         smtp_command_loop,
1158                                         NULL,
1159                                         CitadelServiceSMTPS_MTA);
1160 #endif
1161
1162                 CtdlRegisterServiceHook(config.c_msa_port,      /* SMTP MSA */
1163                                         NULL,
1164                                         smtp_msa_greeting,
1165                                         smtp_command_loop,
1166                                         NULL,
1167                                         CitadelServiceSMTP_MSA);
1168
1169                 CtdlRegisterServiceHook(0,                      /* local LMTP */
1170                                         file_lmtp_socket,
1171                                         lmtp_greeting,
1172                                         smtp_command_loop,
1173                                         NULL,
1174                                         CitadelServiceSMTP_LMTP);
1175
1176                 CtdlRegisterServiceHook(0,                      /* local LMTP */
1177                                         file_lmtp_unfiltered_socket,
1178                                         lmtp_unfiltered_greeting,
1179                                         smtp_command_loop,
1180                                         NULL,
1181                                         CitadelServiceSMTP_LMTP_UNF);
1182
1183                 CtdlRegisterCleanupHook(smtp_cleanup);
1184                 CtdlRegisterSessionHook(smtp_cleanup_function, EVT_STOP, PRIO_STOP + 250);
1185         }
1186
1187         /* return our module name for the log */
1188         return "smtp";
1189 }