src/src/smtp_in.c

   1 /* $Cambridge: exim/src/src/smtp_in.c,v 1.8 2005/01/04 10:00:42 ph10 Exp $ */
   2
   3 /*************************************************
   4 *     Exim - an Internet mail transport agent    *
   5 *************************************************/
   6
   7 /* Copyright (c) University of Cambridge 1995 - 2005 */
   8 /* See the file NOTICE for conditions of use and distribution. */
   9
  10 /* Functions for handling an incoming SMTP call. */
  11
  12
  13 #include "exim.h"
  14
  15
  16 /* Initialize for TCP wrappers if so configured. It appears that the macro
  17 HAVE_IPV6 is used in some versions of the tcpd.h header, so we unset it before
  18 including that header, and restore its value afterwards. */
  19
  20 #ifdef USE_TCP_WRAPPERS
  21
  22   #if HAVE_IPV6
  23   #define EXIM_HAVE_IPV6
  24   #endif
  25   #undef HAVE_IPV6
  26   #include <tcpd.h>
  27   #undef HAVE_IPV6
  28   #ifdef EXIM_HAVE_IPV6
  29   #define HAVE_IPV6 TRUE
  30   #endif
  31
  32 int allow_severity = LOG_INFO;
  33 int deny_severity  = LOG_NOTICE;
  34 #endif
  35
  36
  37 /* Size of buffer for reading SMTP commands */
  38
  39 #define cmd_buffer_size  512      /* Ref. RFC 821 */
  40
  41 /* Size of buffer for reading SMTP incoming packets */
  42
  43 #define in_buffer_size  8192
  44
  45 /* Structure for SMTP command list */
  46
  47 typedef struct {
  48   char *name;
  49   int len;
  50   short int cmd;
  51   short int has_arg;
  52   short int is_mail_cmd;
  53 } smtp_cmd_list;
  54
  55 /* Codes for identifying commands. We order them so that those that come first
  56 are those for which synchronization is always required. Checking this can help
  57 block some spam.  */
  58
  59 enum {
  60   /* These commands are required to be synchronized, i.e. to be the last in a
  61   block of commands when pipelining. */
  62
  63   HELO_CMD, EHLO_CMD, DATA_CMD, /* These are listed in the pipelining */
  64   VRFY_CMD, EXPN_CMD, NOOP_CMD, /* RFC as requiring synchronization */
  65   ETRN_CMD,                     /* This by analogy with TURN from the RFC */
  66   STARTTLS_CMD,                 /* Required by the STARTTLS RFC */
  67
  68   /* This is a dummy to identify the non-sync commands when pipelining */
  69
  70   NON_SYNC_CMD_PIPELINING,
  71
  72   /* These commands need not be synchronized when pipelining */
  73
  74   MAIL_CMD, RCPT_CMD, RSET_CMD,
  75
  76   /* This is a dummy to identify the non-sync commands when not pipelining */
  77
  78   NON_SYNC_CMD_NON_PIPELINING,
  79
  80   /* I have been unable to find a statement about the use of pipelining
  81   with AUTH, so to be on the safe side it is here, though I kind of feel
  82   it should be up there with the synchronized commands. */
  83
  84   AUTH_CMD,
  85
  86   /* I'm not sure about these, but I don't think they matter. */
  87
  88   QUIT_CMD, HELP_CMD,
  89
  90   /* These are specials that don't correspond to actual commands */
  91
  92   EOF_CMD, OTHER_CMD, BADARG_CMD, BADCHAR_CMD, BADSYN_CMD,
  93   TOO_MANY_NONMAIL_CMD };
  94
  95
  96
  97 /*************************************************
  98 *                Local static variables          *
  99 *************************************************/
 100
 101 static auth_instance *authenticated_by;
 102 static BOOL auth_advertised;
 103 #ifdef SUPPORT_TLS
 104 static BOOL tls_advertised;
 105 #endif
 106 static BOOL esmtp;
 107 static BOOL helo_required = FALSE;
 108 static BOOL helo_verify = FALSE;
 109 static BOOL helo_seen;
 110 static BOOL helo_accept_junk;
 111 static BOOL count_nonmail;
 112 static BOOL pipelining_advertised;
 113 static int  nonmail_command_count;
 114 static int  synprot_error_count;
 115 static int  unknown_command_count;
 116 static int  sync_cmd_limit;
 117 static int  smtp_write_error = 0;
 118
 119 static uschar *smtp_data;
 120
 121 static uschar *cmd_buffer;
 122
 123 /* We need to know the position of RSET, HELO, EHLO, AUTH, and STARTTLS. Their
 124 final fields of all except AUTH are forced TRUE at the start of a new message
 125 setup, to allow one of each between messages that is not counted as a nonmail
 126 command. (In fact, only one of HELO/EHLO is not counted.) Also, we have to
 127 allow a new EHLO after starting up TLS.
 128
 129 AUTH is "falsely" labelled as a mail command initially, so that it doesn't get
 130 counted. However, the flag is changed when AUTH is received, so that multiple
 131 failing AUTHs will eventually hit the limit. After a successful AUTH, another
 132 AUTH is already forbidden. After a TLS session is started, AUTH's flag is again
 133 forced TRUE, to allow for the re-authentication that can happen at that point.
 134
 135 QUIT is also "falsely" labelled as a mail command so that it doesn't up the
 136 count of non-mail commands and possibly provoke an error. */
 137
 138 static smtp_cmd_list cmd_list[] = {
 139   { "rset",       sizeof("rset")-1,       RSET_CMD, FALSE, FALSE },  /* First */
 140   { "helo",       sizeof("helo")-1,       HELO_CMD, TRUE,  FALSE },
 141   { "ehlo",       sizeof("ehlo")-1,       EHLO_CMD, TRUE,  FALSE },
 142   { "auth",       sizeof("auth")-1,       AUTH_CMD, TRUE,  TRUE  },
 143   #ifdef SUPPORT_TLS
 144   { "starttls",   sizeof("starttls")-1,   STARTTLS_CMD, FALSE, FALSE },
 145   #endif
 146
 147 /* If you change anything above here, also fix the definitions below. */
 148
 149   { "mail from:", sizeof("mail from:")-1, MAIL_CMD, TRUE,  TRUE  },
 150   { "rcpt to:",   sizeof("rcpt to:")-1,   RCPT_CMD, TRUE,  TRUE  },
 151   { "data",       sizeof("data")-1,       DATA_CMD, FALSE, TRUE  },
 152   { "quit",       sizeof("quit")-1,       QUIT_CMD, FALSE, TRUE  },
 153   { "noop",       sizeof("noop")-1,       NOOP_CMD, TRUE,  FALSE },
 154   { "etrn",       sizeof("etrn")-1,       ETRN_CMD, TRUE,  FALSE },
 155   { "vrfy",       sizeof("vrfy")-1,       VRFY_CMD, TRUE,  FALSE },
 156   { "expn",       sizeof("expn")-1,       EXPN_CMD, TRUE,  FALSE },
 157   { "help",       sizeof("help")-1,       HELP_CMD, TRUE,  FALSE }
 158 };
 159
 160 static smtp_cmd_list *cmd_list_end =
 161   cmd_list + sizeof(cmd_list)/sizeof(smtp_cmd_list);
 162
 163 #define CMD_LIST_RSET      0
 164 #define CMD_LIST_HELO      1
 165 #define CMD_LIST_EHLO      2
 166 #define CMD_LIST_AUTH      3
 167 #define CMD_LIST_STARTTLS  4
 168
 169 static uschar *protocols[] = {
 170   US"local-smtp",        /* HELO */
 171   US"local-smtps",       /* The rare case EHLO->STARTTLS->HELO */
 172   US"local-esmtp",       /* EHLO */
 173   US"local-esmtps",      /* EHLO->STARTTLS->EHLO */
 174   US"local-esmtpa",      /* EHLO->AUTH */
 175   US"local-esmtpsa"      /* EHLO->STARTTLS->EHLO->AUTH */
 176   };
 177
 178 #define pnormal  0
 179 #define pextend  2
 180 #define pcrpted  1  /* added to pextend or pnormal */
 181 #define pauthed  2  /* added to pextend */
 182 #define pnlocal  6  /* offset to remove "local" */
 183
 184 /* When reading SMTP from a remote host, we have to use our own versions of the
 185 C input-reading functions, in order to be able to flush the SMTP output only
 186 when about to read more data from the socket. This is the only way to get
 187 optimal performance when the client is using pipelining. Flushing for every
 188 command causes a separate packet and reply packet each time; saving all the
 189 responses up (when pipelining) combines them into one packet and one response.
 190
 191 For simplicity, these functions are used for *all* SMTP input, not only when
 192 receiving over a socket. However, after setting up a secure socket (SSL), input
 193 is read via the OpenSSL library, and another set of functions is used instead
 194 (see tls.c).
 195
 196 These functions are set in the receive_getc etc. variables and called with the
 197 same interface as the C functions. However, since there can only ever be
 198 one incoming SMTP call, we just use a single buffer and flags. There is no need
 199 to implement a complicated private FILE-like structure.*/
 200
 201 static uschar *smtp_inbuffer;
 202 static uschar *smtp_inptr;
 203 static uschar *smtp_inend;
 204 static int     smtp_had_eof;
 205 static int     smtp_had_error;
 206
 207
 208 /*************************************************
 209 *          SMTP version of getc()                *
 210 *************************************************/
 211
 212 /* This gets the next byte from the SMTP input buffer. If the buffer is empty,
 213 it flushes the output, and refills the buffer, with a timeout. The signal
 214 handler is set appropriately by the calling function. This function is not used
 215 after a connection has negotated itself into an TLS/SSL state.
 216
 217 Arguments:  none
 218 Returns:    the next character or EOF
 219 */
 220
 221 int
 222 smtp_getc(void)
 223 {
 224 if (smtp_inptr >= smtp_inend)
 225   {
 226   int rc, save_errno;
 227   fflush(smtp_out);
 228   if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
 229   rc = read(fileno(smtp_in), smtp_inbuffer, in_buffer_size);
 230   save_errno = errno;
 231   alarm(0);
 232   if (rc <= 0)
 233     {
 234     /* Must put the error text in fixed store, because this might be during
 235     header reading, where it releases unused store above the header. */
 236     if (rc < 0)
 237       {
 238       smtp_had_error = save_errno;
 239       smtp_read_error = string_copy_malloc(
 240         string_sprintf(" (error: %s)", strerror(save_errno)));
 241       }
 242     else smtp_had_eof = 1;
 243     return EOF;
 244     }
 245   smtp_inend = smtp_inbuffer + rc;
 246   smtp_inptr = smtp_inbuffer;
 247   }
 248 return *smtp_inptr++;
 249 }
 250
 251
 252
 253 /*************************************************
 254 *          SMTP version of ungetc()              *
 255 *************************************************/
 256
 257 /* Puts a character back in the input buffer. Only ever
 258 called once.
 259
 260 Arguments:
 261   ch           the character
 262
 263 Returns:       the character
 264 */
 265
 266 int
 267 smtp_ungetc(int ch)
 268 {
 269 *(--smtp_inptr) = ch;
 270 return ch;
 271 }
 272
 273
 274
 275
 276 /*************************************************
 277 *          SMTP version of feof()                *
 278 *************************************************/
 279
 280 /* Tests for a previous EOF
 281
 282 Arguments:     none
 283 Returns:       non-zero if the eof flag is set
 284 */
 285
 286 int
 287 smtp_feof(void)
 288 {
 289 return smtp_had_eof;
 290 }
 291
 292
 293
 294
 295 /*************************************************
 296 *          SMTP version of ferror()              *
 297 *************************************************/
 298
 299 /* Tests for a previous read error, and returns with errno
 300 restored to what it was when the error was detected.
 301
 302 Arguments:     none
 303 Returns:       non-zero if the error flag is set
 304 */
 305
 306 int
 307 smtp_ferror(void)
 308 {
 309 errno = smtp_had_error;
 310 return smtp_had_error;
 311 }
 312
 313
 314
 315
 316 /*************************************************
 317 *     Write formatted string to SMTP channel     *
 318 *************************************************/
 319
 320 /* This is a separate function so that we don't have to repeat everything for
 321 TLS support or debugging. It is global so that the daemon and the
 322 authentication functions can use it. It does not return any error indication,
 323 because major problems such as dropped connections won't show up till an output
 324 flush for non-TLS connections. The smtp_fflush() function is available for
 325 checking that: for convenience, TLS output errors are remembered here so that
 326 they are also picked up later by smtp_fflush().
 327
 328 Arguments:
 329   format      format string
 330   ...         optional arguments
 331
 332 Returns:      nothing
 333 */
 334
 335 void
 336 smtp_printf(char *format, ...)
 337 {
 338 va_list ap;
 339
 340 DEBUG(D_receive)
 341   {
 342   va_start(ap, format);
 343   (void) string_vformat(big_buffer, big_buffer_size, format, ap);
 344   debug_printf("SMTP>> %s", big_buffer);
 345   }
 346
 347 va_start(ap, format);
 348
 349 /* If in a TLS session we have to format the string, and then write it using a
 350 TLS function. */
 351
 352 #ifdef SUPPORT_TLS
 353 if (tls_active >= 0)
 354   {
 355   if (!string_vformat(big_buffer, big_buffer_size, format, ap))
 356     {
 357     log_write(0, LOG_MAIN|LOG_PANIC, "string too large in smtp_printf");
 358     smtp_closedown(US"Unexpected error");
 359     exim_exit(EXIT_FAILURE);
 360     }
 361   if (tls_write(big_buffer, Ustrlen(big_buffer)) < 0) smtp_write_error = -1;
 362   }
 363 else
 364 #endif
 365
 366 /* Otherwise, just use the standard library function. */
 367
 368 if (vfprintf(smtp_out, format, ap) < 0) smtp_write_error = -1;
 369 va_end(ap);
 370 }
 371
 372
 373
 374 /*************************************************
 375 *        Flush SMTP out and check for error      *
 376 *************************************************/
 377
 378 /* This function isn't currently used within Exim (it detects errors when it
 379 tries to read the next SMTP input), but is available for use in local_scan().
 380 For non-TLS connections, it flushes the output and checks for errors. For
 381 TLS-connections, it checks for a previously-detected TLS write error.
 382
 383 Arguments:  none
 384 Returns:    0 for no error; -1 after an error
 385 */
 386
 387 int
 388 smtp_fflush(void)
 389 {
 390 if (tls_active < 0 && fflush(smtp_out) != 0) smtp_write_error = -1;
 391 return smtp_write_error;
 392 }
 393
 394
 395
 396 /*************************************************
 397 *          SMTP command read timeout             *
 398 *************************************************/
 399
 400 /* Signal handler for timing out incoming SMTP commands. This attempts to
 401 finish off tidily.
 402
 403 Argument: signal number (SIGALRM)
 404 Returns:  nothing
 405 */
 406
 407 static void
 408 command_timeout_handler(int sig)
 409 {
 410 sig = sig;    /* Keep picky compilers happy */
 411 log_write(L_lost_incoming_connection,
 412           LOG_MAIN, "SMTP command timeout on%s connection from %s",
 413           (tls_active >= 0)? " TLS" : "",
 414           host_and_ident(FALSE));
 415 if (smtp_batched_input)
 416   moan_smtp_batch(NULL, "421 SMTP command timeout");  /* Does not return */
 417 smtp_printf("421 %s: SMTP command timeout - closing connection\r\n",
 418   smtp_active_hostname);
 419 mac_smtp_fflush();
 420 exim_exit(EXIT_FAILURE);
 421 }
 422
 423
 424
 425 /*************************************************
 426 *               SIGTERM received                 *
 427 *************************************************/
 428
 429 /* Signal handler for handling SIGTERM. Again, try to finish tidily.
 430
 431 Argument: signal number (SIGTERM)
 432 Returns:  nothing
 433 */
 434
 435 static void
 436 command_sigterm_handler(int sig)
 437 {
 438 sig = sig;    /* Keep picky compilers happy */
 439 log_write(0, LOG_MAIN, "%s closed after SIGTERM", smtp_get_connection_info());
 440 if (smtp_batched_input)
 441   moan_smtp_batch(NULL, "421 SIGTERM received");  /* Does not return */
 442 smtp_printf("421 %s: Service not available - closing connection\r\n",
 443   smtp_active_hostname);
 444 exim_exit(EXIT_FAILURE);
 445 }
 446
 447
 448
 449 /*************************************************
 450 *           Read one command line                *
 451 *************************************************/
 452
 453 /* Strictly, SMTP commands coming over the net are supposed to end with CRLF.
 454 There are sites that don't do this, and in any case internal SMTP probably
 455 should check only for LF. Consequently, we check here for LF only. The line
 456 ends up with [CR]LF removed from its end. If we get an overlong line, treat as
 457 an unknown command. The command is read into the static cmd_buffer.
 458
 459 The character reading routine sets up a timeout for each block actually read
 460 from the input (which may contain more than one command). We set up a special
 461 signal handler that closes down the session on a timeout. Control does not
 462 return when it runs.
 463
 464 Arguments:
 465   check_sync   if TRUE, check synchronization rules if global option is TRUE
 466
 467 Returns:       a code identifying the command (enumerated above)
 468 */
 469
 470 static int
 471 smtp_read_command(BOOL check_sync)
 472 {
 473 int c;
 474 int ptr = 0;
 475 smtp_cmd_list *p;
 476 BOOL hadnull = FALSE;
 477
 478 os_non_restarting_signal(SIGALRM, command_timeout_handler);
 479
 480 while ((c = (receive_getc)()) != '\n' && c != EOF)
 481   {
 482   if (ptr >= cmd_buffer_size)
 483     {
 484     os_non_restarting_signal(SIGALRM, sigalrm_handler);
 485     return OTHER_CMD;
 486     }
 487   if (c == 0)
 488     {
 489     hadnull = TRUE;
 490     c = '?';
 491     }
 492   cmd_buffer[ptr++] = c;
 493   }
 494
 495 receive_linecount++;    /* For BSMTP errors */
 496 os_non_restarting_signal(SIGALRM, sigalrm_handler);
 497
 498 /* If hit end of file, return pseudo EOF command. Whether we have a
 499 part-line already read doesn't matter, since this is an error state. */
 500
 501 if (c == EOF) return EOF_CMD;
 502
 503 /* Remove any CR and white space at the end of the line, and terminate the
 504 string. */
 505
 506 while (ptr > 0 && isspace(cmd_buffer[ptr-1])) ptr--;
 507 cmd_buffer[ptr] = 0;
 508
 509 DEBUG(D_receive) debug_printf("SMTP<< %s\n", cmd_buffer);
 510
 511 /* NULLs are not allowed in SMTP commands */
 512
 513 if (hadnull) return BADCHAR_CMD;
 514
 515 /* Scan command list and return identity, having set the data pointer
 516 to the start of the actual data characters. Check for SMTP synchronization
 517 if required. */
 518
 519 for (p = cmd_list; p < cmd_list_end; p++)
 520   {
 521   if (strncmpic(cmd_buffer, US p->name, p->len) == 0)
 522     {
 523     if (smtp_inptr < smtp_inend &&                     /* Outstanding input */
 524         p->cmd < sync_cmd_limit &&                     /* Command should sync */
 525         check_sync &&                                  /* Local flag set */
 526         smtp_enforce_sync &&                           /* Global flag set */
 527         sender_host_address != NULL &&                 /* Not local input */
 528         !sender_host_notsocket)                        /* Really is a socket */
 529       return BADSYN_CMD;
 530
 531     /* Point after the command, but don't skip over leading spaces till after
 532     the following test, so that if it fails, the command name can easily be
 533     logged. */
 534
 535     smtp_data = cmd_buffer + p->len;
 536
 537     /* Count non-mail commands from those hosts that are controlled in this
 538     way. The default is all hosts. We don't waste effort checking the list
 539     until we get a non-mail command, but then cache the result to save checking
 540     again. If there's a DEFER while checking the host, assume it's in the list.
 541
 542     Note that one instance of RSET, EHLO/HELO, and STARTTLS is allowed at the
 543     start of each incoming message by fiddling with the value in the table. */
 544
 545     if (!p->is_mail_cmd)
 546       {
 547       if (count_nonmail == TRUE_UNSET) count_nonmail =
 548         verify_check_host(&smtp_accept_max_nonmail_hosts) != FAIL;
 549       if (count_nonmail && ++nonmail_command_count > smtp_accept_max_nonmail)
 550         return TOO_MANY_NONMAIL_CMD;
 551       }
 552
 553     /* Get the data pointer over leading spaces and return; if there is no data
 554     for a command that expects it, we give the error centrally here. */
 555
 556     while (isspace(*smtp_data)) smtp_data++;
 557     return (p->has_arg || *smtp_data == 0)? p->cmd : BADARG_CMD;
 558     }
 559   }
 560
 561 /* Enforce synchronization for unknown commands */
 562
 563 if (smtp_inptr < smtp_inend &&                     /* Outstanding input */
 564     check_sync &&                                  /* Local flag set */
 565     smtp_enforce_sync &&                           /* Global flag set */
 566     sender_host_address != NULL &&                 /* Not local input */
 567     !sender_host_notsocket)                        /* Really is a socket */
 568   return BADSYN_CMD;
 569
 570 return OTHER_CMD;
 571 }
 572
 573
 574
 575 /*************************************************
 576 *          Forced closedown of call              *
 577 *************************************************/
 578
 579 /* This function is called from log.c when Exim is dying because of a serious
 580 disaster, and also from some other places. If an incoming non-batched SMTP
 581 channel is open, it swallows the rest of the incoming message if in the DATA
 582 phase, sends the reply string, and gives an error to all subsequent commands
 583 except QUIT. The existence of an SMTP call is detected by the non-NULLness of
 584 smtp_in.
 585
 586 Argument:   SMTP reply string to send, excluding the code
 587 Returns:    nothing
 588 */
 589
 590 void
 591 smtp_closedown(uschar *message)
 592 {
 593 if (smtp_in == NULL || smtp_batched_input) return;
 594 receive_swallow_smtp();
 595 smtp_printf("421 %s\r\n", message);
 596
 597 for (;;)
 598   {
 599   switch(smtp_read_command(FALSE))
 600     {
 601     case EOF_CMD:
 602     return;
 603
 604     case QUIT_CMD:
 605     smtp_printf("221 %s closing connection\r\n", smtp_active_hostname);
 606     mac_smtp_fflush();
 607     return;
 608
 609     case RSET_CMD:
 610     smtp_printf("250 Reset OK\r\n");
 611     break;
 612
 613     default:
 614     smtp_printf("421 %s\r\n", message);
 615     break;
 616     }
 617   }
 618 }
 619
 620
 621
 622
 623 /*************************************************
 624 *        Set up connection info for logging      *
 625 *************************************************/
 626
 627 /* This function is called when logging information about an SMTP connection.
 628 It sets up appropriate source information, depending on the type of connection.
 629
 630 Argument:    none
 631 Returns:     a string describing the connection
 632 */
 633
 634 uschar *
 635 smtp_get_connection_info(void)
 636 {
 637 if (host_checking)
 638   return string_sprintf("SMTP connection from %s", sender_fullhost);
 639
 640 if (sender_host_unknown || sender_host_notsocket)
 641   return string_sprintf("SMTP connection from %s", sender_ident);
 642
 643 if (is_inetd)
 644   return string_sprintf("SMTP connection from %s (via inetd)", sender_fullhost);
 645
 646 if ((log_extra_selector & LX_incoming_interface) != 0 &&
 647      interface_address != NULL)
 648   return string_sprintf("SMTP connection from %s I=[%s]:%d", sender_fullhost,
 649     interface_address, interface_port);
 650
 651 return string_sprintf("SMTP connection from %s", sender_fullhost);
 652 }
 653
 654
 655
 656 /*************************************************
 657 *   Check HELO line and set sender_helo_name     *
 658 *************************************************/
 659
 660 /* Check the format of a HELO line. The data for HELO/EHLO is supposed to be
 661 the domain name of the sending host, or an ip literal in square brackets. The
 662 arrgument is placed in sender_helo_name, which is in malloc store, because it
 663 must persist over multiple incoming messages. If helo_accept_junk is set, this
 664 host is permitted to send any old junk (needed for some broken hosts).
 665 Otherwise, helo_allow_chars can be used for rogue characters in general
 666 (typically people want to let in underscores).
 667
 668 Argument:
 669   s       the data portion of the line (already past any white space)
 670
 671 Returns:  TRUE or FALSE
 672 */
 673
 674 static BOOL
 675 check_helo(uschar *s)
 676 {
 677 uschar *start = s;
 678 uschar *end = s + Ustrlen(s);
 679 BOOL yield = helo_accept_junk;
 680
 681 /* Discard any previous helo name */
 682
 683 if (sender_helo_name != NULL)
 684   {
 685   store_free(sender_helo_name);
 686   sender_helo_name = NULL;
 687   }
 688
 689 /* Skip tests if junk is permitted. */
 690
 691 if (!yield)
 692   {
 693   /* Allow the new standard form for IPv6 address literals, namely,
 694   [IPv6:....], and because someone is bound to use it, allow an equivalent
 695   IPv4 form. Allow plain addresses as well. */
 696
 697   if (*s == '[')
 698     {
 699     if (end[-1] == ']')
 700       {
 701       end[-1] = 0;
 702       if (strncmpic(s, US"[IPv6:", 6) == 0)
 703         yield = (string_is_ip_address(s+6, NULL) == 6);
 704       else if (strncmpic(s, US"[IPv4:", 6) == 0)
 705         yield = (string_is_ip_address(s+6, NULL) == 4);
 706       else
 707         yield = (string_is_ip_address(s+1, NULL) != 0);
 708       end[-1] = ']';
 709       }
 710     }
 711
 712   /* Non-literals must be alpha, dot, hyphen, plus any non-valid chars
 713   that have been configured (usually underscore - sigh). */
 714
 715   else if (*s != 0)
 716     {
 717     yield = TRUE;
 718     while (*s != 0)
 719       {
 720       if (!isalnum(*s) && *s != '.' && *s != '-' &&
 721           Ustrchr(helo_allow_chars, *s) == NULL)
 722         {
 723         yield = FALSE;
 724         break;
 725         }
 726       s++;
 727       }
 728     }
 729   }
 730
 731 /* Save argument if OK */
 732
 733 if (yield) sender_helo_name = string_copy_malloc(start);
 734 return yield;
 735 }
 736
 737
 738
 739
 740
 741 /*************************************************
 742 *         Extract SMTP command option            *
 743 *************************************************/
 744
 745 /* This function picks the next option setting off the end of smtp_data. It
 746 is called for MAIL FROM and RCPT TO commands, to pick off the optional ESMTP
 747 things that can appear there.
 748
 749 Arguments:
 750    name           point this at the name
 751    value          point this at the data string
 752
 753 Returns:          TRUE if found an option
 754 */
 755
 756 static BOOL
 757 extract_option(uschar **name, uschar **value)
 758 {
 759 uschar *n;
 760 uschar *v = smtp_data + Ustrlen(smtp_data) -1;
 761 while (isspace(*v)) v--;
 762 v[1] = 0;
 763
 764 while (v > smtp_data && *v != '=' && !isspace(*v)) v--;
 765 if (*v != '=') return FALSE;
 766
 767 n = v;
 768 while(isalpha(n[-1])) n--;
 769
 770 if (n[-1] != ' ') return FALSE;
 771
 772 n[-1] = 0;
 773 *name = n;
 774 *v++ = 0;
 775 *value = v;
 776 return TRUE;
 777 }
 778
 779
 780
 781
 782
 783
 784
 785 /*************************************************
 786 *         Reset for new message                  *
 787 *************************************************/
 788
 789 /* This function is called whenever the SMTP session is reset from
 790 within either of the setup functions.
 791
 792 Argument:   the stacking pool storage reset point
 793 Returns:    nothing
 794 */
 795
 796 static void
 797 smtp_reset(void *reset_point)
 798 {
 799 int i;
 800 store_reset(reset_point);
 801 recipients_list = NULL;
 802 rcpt_count = rcpt_defer_count = rcpt_fail_count =
 803   raw_recipients_count = recipients_count = recipients_list_max = 0;
 804 message_size = -1;
 805 acl_warn_headers = NULL;
 806 queue_only_policy = FALSE;
 807 deliver_freeze = FALSE;                              /* Can be set by ACL */
 808 fake_reject = FALSE;                                 /* Can be set by ACL */
 809 #ifdef WITH_CONTENT_SCAN
 810 no_mbox_unspool = FALSE;                             /* Can be set by ACL */
 811 #endif
 812 submission_mode = FALSE;                             /* Can be set by ACL */
 813 active_local_from_check = local_from_check;          /* Can be set by ACL */
 814 active_local_sender_retain = local_sender_retain;    /* Can be set by ACL */
 815 sender_address = NULL;
 816 raw_sender = NULL;                  /* After SMTP rewrite, before qualifying */
 817 sender_address_unrewritten = NULL;  /* Set only after verify rewrite */
 818 sender_verified_list = NULL;        /* No senders verified */
 819 memset(sender_address_cache, 0, sizeof(sender_address_cache));
 820 memset(sender_domain_cache, 0, sizeof(sender_domain_cache));
 821 authenticated_sender = NULL;
 822 #ifdef EXPERIMENTAL_BRIGHTMAIL
 823 bmi_run = 0;
 824 bmi_verdicts = NULL;
 825 #endif
 826 #ifdef EXPERIMENTAL_SPF
 827 spf_header_comment = NULL;
 828 spf_received = NULL;
 829 spf_result = NULL;
 830 spf_smtp_comment = NULL;
 831 #endif
 832 body_linecount = body_zerocount = 0;
 833
 834 for (i = 0; i < ACL_M_MAX; i++) acl_var[ACL_C_MAX + i] = NULL;
 835
 836 /* The message body variables use malloc store. They may be set if this is
 837 not the first message in an SMTP session and the previous message caused them
 838 to be referenced in an ACL. */
 839
 840 if (message_body != NULL)
 841   {
 842   store_free(message_body);
 843   message_body = NULL;
 844   }
 845
 846 if (message_body_end != NULL)
 847   {
 848   store_free(message_body_end);
 849   message_body_end = NULL;
 850   }
 851
 852 /* Warning log messages are also saved in malloc store. They are saved to avoid
 853 repetition in the same message, but it seems right to repeat them for different
 854 messagess. */
 855
 856 while (acl_warn_logged != NULL)
 857   {
 858   string_item *this = acl_warn_logged;
 859   acl_warn_logged = acl_warn_logged->next;
 860   store_free(this);
 861   }
 862 }
 863
 864
 865
 866
 867
 868 /*************************************************
 869 *  Initialize for incoming batched SMTP message  *
 870 *************************************************/
 871
 872 /* This function is called from smtp_setup_msg() in the case when
 873 smtp_batched_input is true. This happens when -bS is used to pass a whole batch
 874 of messages in one file with SMTP commands between them. All errors must be
 875 reported by sending a message, and only MAIL FROM, RCPT TO, and DATA are
 876 relevant. After an error on a sender, or an invalid recipient, the remainder
 877 of the message is skipped. The value of received_protocol is already set.
 878
 879 Argument: none
 880 Returns:  > 0 message successfully started (reached DATA)
 881           = 0 QUIT read or end of file reached
 882           < 0 should not occur
 883 */
 884
 885 static int
 886 smtp_setup_batch_msg(void)
 887 {
 888 int done = 0;
 889 void *reset_point = store_get(0);
 890
 891 /* Save the line count at the start of each transaction - single commands
 892 like HELO and RSET count as whole transactions. */
 893
 894 bsmtp_transaction_linecount = receive_linecount;
 895
 896 if ((receive_feof)()) return 0;   /* Treat EOF as QUIT */
 897
 898 smtp_reset(reset_point);                /* Reset for start of message */
 899
 900 /* Deal with SMTP commands. This loop is exited by setting done to a POSITIVE
 901 value. The values are 2 larger than the required yield of the function. */
 902
 903 while (done <= 0)
 904   {
 905   uschar *errmess;
 906   uschar *recipient = NULL;
 907   int start, end, sender_domain, recipient_domain;
 908
 909   switch(smtp_read_command(FALSE))
 910     {
 911     /* The HELO/EHLO commands set sender_address_helo if they have
 912     valid data; otherwise they are ignored, except that they do
 913     a reset of the state. */
 914
 915     case HELO_CMD:
 916     case EHLO_CMD:
 917
 918     check_helo(smtp_data);
 919     /* Fall through */
 920
 921     case RSET_CMD:
 922     smtp_reset(reset_point);
 923     bsmtp_transaction_linecount = receive_linecount;
 924     break;
 925
 926
 927     /* The MAIL FROM command requires an address as an operand. All we
 928     do here is to parse it for syntactic correctness. The form "<>" is
 929     a special case which converts into an empty string. The start/end
 930     pointers in the original are not used further for this address, as
 931     it is the canonical extracted address which is all that is kept. */
 932
 933     case MAIL_CMD:
 934     if (sender_address != NULL)
 935       /* The function moan_smtp_batch() does not return. */
 936       moan_smtp_batch(cmd_buffer, "503 Sender already given");
 937
 938     if (smtp_data[0] == 0)
 939       /* The function moan_smtp_batch() does not return. */
 940       moan_smtp_batch(cmd_buffer, "501 MAIL FROM must have an address operand");
 941
 942     /* Reset to start of message */
 943
 944     smtp_reset(reset_point);
 945
 946     /* Apply SMTP rewrite */
 947
 948     raw_sender = ((rewrite_existflags & rewrite_smtp) != 0)?
 949       rewrite_one(smtp_data, rewrite_smtp|rewrite_smtp_sender, NULL, FALSE,
 950         US"", global_rewrite_rules) : smtp_data;
 951
 952     /* Extract the address; the TRUE flag allows <> as valid */
 953
 954     raw_sender =
 955       parse_extract_address(raw_sender, &errmess, &start, &end, &sender_domain,
 956         TRUE);
 957
 958     if (raw_sender == NULL)
 959       /* The function moan_smtp_batch() does not return. */
 960       moan_smtp_batch(cmd_buffer, "501 %s", errmess);
 961
 962     sender_address = string_copy(raw_sender);
 963
 964     /* Qualify unqualified sender addresses if permitted to do so. */
 965
 966     if (sender_domain == 0 && sender_address[0] != 0 && sender_address[0] != '@')
 967       {
 968       if (allow_unqualified_sender)
 969         {
 970         sender_address = rewrite_address_qualify(sender_address, FALSE);
 971         DEBUG(D_receive) debug_printf("unqualified address %s accepted "
 972           "and rewritten\n", raw_sender);
 973         }
 974       /* The function moan_smtp_batch() does not return. */
 975       else moan_smtp_batch(cmd_buffer, "501 sender address must contain "
 976         "a domain");
 977       }
 978     break;
 979
 980
 981     /* The RCPT TO command requires an address as an operand. All we do
 982     here is to parse it for syntactic correctness. There may be any number
 983     of RCPT TO commands, specifying multiple senders. We build them all into
 984     a data structure that is in argc/argv format. The start/end values
 985     given by parse_extract_address are not used, as we keep only the
 986     extracted address. */
 987
 988     case RCPT_CMD:
 989     if (sender_address == NULL)
 990       /* The function moan_smtp_batch() does not return. */
 991       moan_smtp_batch(cmd_buffer, "503 No sender yet given");
 992
 993     if (smtp_data[0] == 0)
 994       /* The function moan_smtp_batch() does not return. */
 995       moan_smtp_batch(cmd_buffer, "501 RCPT TO must have an address operand");
 996
 997     /* Check maximum number allowed */
 998
 999     if (recipients_max > 0 && recipients_count + 1 > recipients_max)
1000       /* The function moan_smtp_batch() does not return. */
1001       moan_smtp_batch(cmd_buffer, "%s too many recipients",
1002         recipients_max_reject? "552": "452");
1003
1004     /* Apply SMTP rewrite, then extract address. Don't allow "<>" as a
1005     recipient address */
1006
1007     recipient = ((rewrite_existflags & rewrite_smtp) != 0)?
1008       rewrite_one(smtp_data, rewrite_smtp, NULL, FALSE, US"",
1009         global_rewrite_rules) : smtp_data;
1010
1011     /* rfc821_domains = TRUE; << no longer needed */
1012     recipient = parse_extract_address(recipient, &errmess, &start, &end,
1013       &recipient_domain, FALSE);
1014     /* rfc821_domains = FALSE; << no longer needed */
1015
1016     if (recipient == NULL)
1017       /* The function moan_smtp_batch() does not return. */
1018       moan_smtp_batch(cmd_buffer, "501 %s", errmess);
1019
1020     /* If the recipient address is unqualified, qualify it if permitted. Then
1021     add it to the list of recipients. */
1022
1023     if (recipient_domain == 0)
1024       {
1025       if (allow_unqualified_recipient)
1026         {
1027         DEBUG(D_receive) debug_printf("unqualified address %s accepted\n",
1028           recipient);
1029         recipient = rewrite_address_qualify(recipient, TRUE);
1030         }
1031       /* The function moan_smtp_batch() does not return. */
1032       else moan_smtp_batch(cmd_buffer, "501 recipient address must contain "
1033         "a domain");
1034       }
1035     receive_add_recipient(recipient, -1);
1036     break;
1037
1038
1039     /* The DATA command is legal only if it follows successful MAIL FROM
1040     and RCPT TO commands. This function is complete when a valid DATA
1041     command is encountered. */
1042
1043     case DATA_CMD:
1044     if (sender_address == NULL || recipients_count <= 0)
1045       {
1046       /* The function moan_smtp_batch() does not return. */
1047       if (sender_address == NULL)
1048         moan_smtp_batch(cmd_buffer,
1049           "503 MAIL FROM:<sender> command must precede DATA");
1050       else
1051         moan_smtp_batch(cmd_buffer,
1052           "503 RCPT TO:<recipient> must precede DATA");
1053       }
1054     else
1055       {
1056       done = 3;                      /* DATA successfully achieved */
1057       message_ended = END_NOTENDED;  /* Indicate in middle of message */
1058       }
1059     break;
1060
1061
1062     /* The VRFY, EXPN, HELP, ETRN, and NOOP commands are ignored. */
1063
1064     case VRFY_CMD:
1065     case EXPN_CMD:
1066     case HELP_CMD:
1067     case NOOP_CMD:
1068     case ETRN_CMD:
1069     bsmtp_transaction_linecount = receive_linecount;
1070     break;
1071
1072
1073     case EOF_CMD:
1074     case QUIT_CMD:
1075     done = 2;
1076     break;
1077
1078
1079     case BADARG_CMD:
1080     /* The function moan_smtp_batch() does not return. */
1081     moan_smtp_batch(cmd_buffer, "501 Unexpected argument data");
1082     break;
1083
1084
1085     case BADCHAR_CMD:
1086     /* The function moan_smtp_batch() does not return. */
1087     moan_smtp_batch(cmd_buffer, "501 Unexpected NULL in SMTP command");
1088     break;
1089
1090
1091     default:
1092     /* The function moan_smtp_batch() does not return. */
1093     moan_smtp_batch(cmd_buffer, "500 Command unrecognized");
1094     break;
1095     }
1096   }
1097
1098 return done - 2;  /* Convert yield values */
1099 }
1100
1101
1102
1103
1104 /*************************************************
1105 *          Start an SMTP session                 *
1106 *************************************************/
1107
1108 /* This function is called at the start of an SMTP session. Thereafter,
1109 smtp_setup_msg() is called to initiate each separate message. This
1110 function does host-specific testing, and outputs the banner line.
1111
1112 Arguments:     none
1113 Returns:       FALSE if the session can not continue; something has
1114                gone wrong, or the connection to the host is blocked
1115 */
1116
1117 BOOL
1118 smtp_start_session(void)
1119 {
1120 int size = 256;
1121 int i, ptr;
1122 uschar *p, *s, *ss;
1123
1124 helo_seen = esmtp = helo_accept_junk = FALSE;
1125 count_nonmail = TRUE_UNSET;
1126 synprot_error_count = unknown_command_count = nonmail_command_count = 0;
1127 smtp_delay_mail = smtp_rlm_base;
1128 auth_advertised = FALSE;
1129 pipelining_advertised = FALSE;
1130 sync_cmd_limit = NON_SYNC_CMD_NON_PIPELINING;
1131
1132 memset(sender_host_cache, 0, sizeof(sender_host_cache));
1133
1134 sender_host_authenticated = NULL;
1135 authenticated_by = NULL;
1136
1137 #ifdef SUPPORT_TLS
1138 tls_cipher = tls_peerdn = NULL;
1139 tls_advertised = FALSE;
1140 #endif
1141
1142 /* Reset ACL connection variables */
1143
1144 for (i = 0; i < ACL_C_MAX; i++) acl_var[i] = NULL;
1145
1146 cmd_buffer = (uschar *)malloc(cmd_buffer_size + 1);  /* allow for trailing 0 */
1147 if (cmd_buffer == NULL)
1148   log_write(0, LOG_MAIN|LOG_PANIC_DIE,
1149     "malloc() failed for SMTP command buffer");
1150
1151 /* For batched input, the protocol setting can be overridden from the
1152 command line by a trusted caller. */
1153
1154 if (smtp_batched_input)
1155   {
1156   if (received_protocol == NULL) received_protocol = US"local-bsmtp";
1157   }
1158
1159 /* For non-batched SMTP input, the protocol setting is forced here. It will be
1160 reset later if any of EHLO/AUTH/STARTTLS are received. */
1161
1162 else
1163   received_protocol =
1164     protocols[pnormal] + ((sender_host_address != NULL)? pnlocal : 0);
1165
1166 /* Set up the buffer for inputting using direct read() calls, and arrange to
1167 call the local functions instead of the standard C ones. */
1168
1169 smtp_inbuffer = (uschar *)malloc(in_buffer_size);
1170 if (smtp_inbuffer == NULL)
1171   log_write(0, LOG_MAIN|LOG_PANIC_DIE, "malloc() failed for SMTP input buffer");
1172 receive_getc = smtp_getc;
1173 receive_ungetc = smtp_ungetc;
1174 receive_feof = smtp_feof;
1175 receive_ferror = smtp_ferror;
1176 smtp_inptr = smtp_inend = smtp_inbuffer;
1177 smtp_had_eof = smtp_had_error = 0;
1178
1179 /* Set up the message size limit; this may be host-specific */
1180
1181 thismessage_size_limit = expand_string_integer(message_size_limit);
1182 if (thismessage_size_limit < 0)
1183   {
1184   if (thismessage_size_limit == -1)
1185     log_write(0, LOG_MAIN|LOG_PANIC, "unable to expand message_size_limit: "
1186       "%s", expand_string_message);
1187   else
1188     log_write(0, LOG_MAIN|LOG_PANIC, "invalid message_size_limit: "
1189       "%s", expand_string_message);
1190   smtp_closedown(US"Temporary local problem - please try later");
1191   return FALSE;
1192   }
1193
1194 /* When a message is input locally via the -bs or -bS options, sender_host_
1195 unknown is set unless -oMa was used to force an IP address, in which case it
1196 is checked like a real remote connection. When -bs is used from inetd, this
1197 flag is not set, causing the sending host to be checked. The code that deals
1198 with IP source routing (if configured) is never required for -bs or -bS and
1199 the flag sender_host_notsocket is used to suppress it.
1200
1201 If smtp_accept_max and smtp_accept_reserve are set, keep some connections in
1202 reserve for certain hosts and/or networks. */
1203
1204 if (!sender_host_unknown)
1205   {
1206   int rc;
1207   BOOL reserved_host = FALSE;
1208
1209   /* Look up IP options (source routing info) on the socket if this is not an
1210   -oMa "host", and if any are found, log them and drop the connection.
1211
1212   Linux (and others now, see below) is different to everyone else, so there
1213   has to be some conditional compilation here. Versions of Linux before 2.1.15
1214   used a structure whose name was "options". Somebody finally realized that
1215   this name was silly, and it got changed to "ip_options". I use the
1216   newer name here, but there is a fudge in the script that sets up os.h
1217   to define a macro in older Linux systems.
1218
1219   Sigh. Linux is a fast-moving target. Another generation of Linux uses
1220   glibc 2, which has chosen ip_opts for the structure name. This is now
1221   really a glibc thing rather than a Linux thing, so the condition name
1222   has been changed to reflect this. It is relevant also to GNU/Hurd.
1223
1224   Mac OS 10.x (Darwin) is like the later glibc versions, but without the
1225   setting of the __GLIBC__ macro, so we can't detect it automatically. There's
1226   a special macro defined in the os.h file.
1227
1228   Some DGUX versions on older hardware appear not to support IP options at
1229   all, so there is now a general macro which can be set to cut out this
1230   support altogether.
1231
1232   How to do this properly in IPv6 is not yet known. */
1233
1234   #if !HAVE_IPV6 && !defined(NO_IP_OPTIONS)
1235
1236   #ifdef GLIBC_IP_OPTIONS
1237     #if (!defined __GLIBC__) || (__GLIBC__ < 2)
1238     #define OPTSTYLE 1
1239     #else
1240     #define OPTSTYLE 2
1241     #endif
1242   #elif defined DARWIN_IP_OPTIONS
1243     #define OPTSTYLE 2
1244   #else
1245     #define OPTSTYLE 3
1246   #endif
1247
1248   if (!host_checking && !sender_host_notsocket)
1249     {
1250     #if OPTSTYLE == 1
1251     SOCKLEN_T optlen = sizeof(struct ip_options) + MAX_IPOPTLEN;
1252     struct ip_options *ipopt = store_get(optlen);
1253     #elif OPTSTYLE == 2
1254     struct ip_opts ipoptblock;
1255     struct ip_opts *ipopt = &ipoptblock;
1256     SOCKLEN_T optlen = sizeof(ipoptblock);
1257     #else
1258     struct ipoption ipoptblock;
1259     struct ipoption *ipopt = &ipoptblock;
1260     SOCKLEN_T optlen = sizeof(ipoptblock);
1261     #endif
1262
1263     /* Occasional genuine failures of getsockopt() have been seen - for
1264     example, "reset by peer". Therefore, just log and give up on this
1265     call, unless the error is ENOPROTOOPT. This error is given by systems
1266     that have the interfaces but not the mechanism - e.g. GNU/Hurd at the time
1267     of writing. So for that error, carry on - we just can't do an IP options
1268     check. */
1269
1270     DEBUG(D_receive) debug_printf("checking for IP options\n");
1271
1272     if (getsockopt(fileno(smtp_out), IPPROTO_IP, IP_OPTIONS, (uschar *)(ipopt),
1273           &optlen) < 0)
1274       {
1275       if (errno != ENOPROTOOPT)
1276         {
1277         log_write(0, LOG_MAIN, "getsockopt() failed from %s: %s",
1278           host_and_ident(FALSE), strerror(errno));
1279         smtp_printf("451 SMTP service not available\r\n");
1280         return FALSE;
1281         }
1282       }
1283
1284     /* Deal with any IP options that are set. On the systems I have looked at,
1285     the value of MAX_IPOPTLEN has been 40, meaning that there should never be
1286     more logging data than will fit in big_buffer. Nevertheless, after somebody
1287     questioned this code, I've added in some paranoid checking. */
1288
1289     else if (optlen > 0)
1290       {
1291       uschar *p = big_buffer;
1292       uschar *pend = big_buffer + big_buffer_size;
1293       uschar *opt, *adptr;
1294       int optcount;
1295       struct in_addr addr;
1296
1297       #if OPTSTYLE == 1
1298       uschar *optstart = (uschar *)(ipopt->__data);
1299       #elif OPTSTYLE == 2
1300       uschar *optstart = (uschar *)(ipopt->ip_opts);
1301       #else
1302       uschar *optstart = (uschar *)(ipopt->ipopt_list);
1303       #endif
1304
1305       DEBUG(D_receive) debug_printf("IP options exist\n");
1306
1307       Ustrcpy(p, "IP options on incoming call:");
1308       p += Ustrlen(p);
1309
1310       for (opt = optstart; opt != NULL &&
1311            opt < (uschar *)(ipopt) + optlen;)
1312         {
1313         switch (*opt)
1314           {
1315           case IPOPT_EOL:
1316           opt = NULL;
1317           break;
1318
1319           case IPOPT_NOP:
1320           opt++;
1321           break;
1322
1323           case IPOPT_SSRR:
1324           case IPOPT_LSRR:
1325           if (!string_format(p, pend-p, " %s [@%s",
1326                (*opt == IPOPT_SSRR)? "SSRR" : "LSRR",
1327                #if OPTSTYLE == 1
1328                inet_ntoa(*((struct in_addr *)(&(ipopt->faddr))))))
1329                #elif OPTSTYLE == 2
1330                inet_ntoa(ipopt->ip_dst)))
1331                #else
1332                inet_ntoa(ipopt->ipopt_dst)))
1333                #endif
1334             {
1335             opt = NULL;
1336             break;
1337             }
1338
1339           p += Ustrlen(p);
1340           optcount = (opt[1] - 3) / sizeof(struct in_addr);
1341           adptr = opt + 3;
1342           while (optcount-- > 0)
1343             {
1344             memcpy(&addr, adptr, sizeof(addr));
1345             if (!string_format(p, pend - p - 1, "%s%s",
1346                   (optcount == 0)? ":" : "@", inet_ntoa(addr)))
1347               {
1348               opt = NULL;
1349               break;
1350               }
1351             p += Ustrlen(p);
1352             adptr += sizeof(struct in_addr);
1353             }
1354           *p++ = ']';
1355           opt += opt[1];
1356           break;
1357
1358           default:
1359             {
1360             int i;
1361             if (pend - p < 4 + 3*opt[1]) { opt = NULL; break; }
1362             Ustrcat(p, "[ ");
1363             p += 2;
1364             for (i = 0; i < opt[1]; i++)
1365               {
1366               sprintf(CS p, "%2.2x ", opt[i]);
1367               p += 3;
1368               }
1369             *p++ = ']';
1370             }
1371           opt += opt[1];
1372           break;
1373           }
1374         }
1375
1376       *p = 0;
1377       log_write(0, LOG_MAIN, "%s", big_buffer);
1378
1379       /* Refuse any call with IP options. This is what tcpwrappers 7.5 does. */
1380
1381       log_write(0, LOG_MAIN|LOG_REJECT,
1382         "connection from %s refused (IP options)", host_and_ident(FALSE));
1383
1384       smtp_printf("554 SMTP service not available\r\n");
1385       return FALSE;
1386       }
1387
1388     /* Length of options = 0 => there are no options */
1389
1390     else DEBUG(D_receive) debug_printf("no IP options found\n");
1391     }
1392   #endif  /* HAVE_IPV6 && !defined(NO_IP_OPTIONS) */
1393
1394   /* Set keep-alive in socket options. The option is on by default. This
1395   setting is an attempt to get rid of some hanging connections that stick in
1396   read() when the remote end (usually a dialup) goes away. */
1397
1398   if (smtp_accept_keepalive && !sender_host_notsocket)
1399     ip_keepalive(fileno(smtp_out), sender_host_address, FALSE);
1400
1401   /* If the current host matches host_lookup, set the name by doing a
1402   reverse lookup. On failure, sender_host_name will be NULL and
1403   host_lookup_failed will be TRUE. This may or may not be serious - optional
1404   checks later. */
1405
1406   if (verify_check_host(&host_lookup) == OK)
1407     {
1408     (void)host_name_lookup();
1409     host_build_sender_fullhost();
1410     }
1411
1412   /* Delay this until we have the full name, if it is looked up. */
1413
1414   set_process_info("handling incoming connection from %s",
1415     host_and_ident(FALSE));
1416
1417   /* Start up TLS if tls_on_connect is set. This is for supporting the legacy
1418   smtps port for use with older style SSL MTAs. */
1419
1420   #ifdef SUPPORT_TLS
1421   if (tls_on_connect && tls_server_start(tls_require_ciphers) != OK)
1422     return FALSE;
1423   #endif
1424
1425   /* Test for explicit connection rejection */
1426
1427   if (verify_check_host(&host_reject_connection) == OK)
1428     {
1429     log_write(L_connection_reject, LOG_MAIN|LOG_REJECT, "refused connection "
1430       "from %s (host_reject_connection)", host_and_ident(FALSE));
1431     smtp_printf("554 SMTP service not available\r\n");
1432     return FALSE;
1433     }
1434
1435   /* Test with TCP Wrappers if so configured */
1436
1437   #ifdef USE_TCP_WRAPPERS
1438   if (!hosts_ctl("exim",
1439          (sender_host_name == NULL)? STRING_UNKNOWN : CS sender_host_name,
1440          (sender_host_address == NULL)? STRING_UNKNOWN : CS sender_host_address,
1441          (sender_ident == NULL)? STRING_UNKNOWN : CS sender_ident))
1442     {
1443     HDEBUG(D_receive) debug_printf("tcp wrappers rejection\n");
1444     log_write(L_connection_reject,
1445               LOG_MAIN|LOG_REJECT, "refused connection from %s "
1446               "(tcp wrappers)", host_and_ident(FALSE));
1447     smtp_printf("554 SMTP service not available\r\n");
1448     return FALSE;
1449     }
1450   #endif
1451
1452   /* Check for reserved slots. Note that the count value doesn't include
1453   this process, as it gets upped in the parent process. */
1454
1455   if (smtp_accept_max > 0 &&
1456       smtp_accept_count + 1 > smtp_accept_max - smtp_accept_reserve)
1457     {
1458     if ((rc = verify_check_host(&smtp_reserve_hosts)) != OK)
1459       {
1460       log_write(L_connection_reject,
1461         LOG_MAIN, "temporarily refused connection from %s: not in "
1462         "reserve list: connected=%d max=%d reserve=%d%s",
1463         host_and_ident(FALSE), smtp_accept_count, smtp_accept_max,
1464         smtp_accept_reserve, (rc == DEFER)? " (lookup deferred)" : "");
1465       smtp_printf("421 %s: Too many concurrent SMTP connections; "
1466         "please try again later\r\n", smtp_active_hostname);
1467       return FALSE;
1468       }
1469     reserved_host = TRUE;
1470     }
1471
1472   /* If a load level above which only messages from reserved hosts are
1473   accepted is set, check the load. For incoming calls via the daemon, the
1474   check is done in the superior process if there are no reserved hosts, to
1475   save a fork. In all cases, the load average will already be available
1476   in a global variable at this point. */
1477
1478   if (smtp_load_reserve >= 0 &&
1479        load_average > smtp_load_reserve &&
1480        !reserved_host &&
1481        verify_check_host(&smtp_reserve_hosts) != OK)
1482     {
1483     log_write(L_connection_reject,
1484       LOG_MAIN, "temporarily refused connection from %s: not in "
1485       "reserve list and load average = %.2f", host_and_ident(FALSE),
1486       (double)load_average/1000.0);
1487     smtp_printf("421 %s: Too much load; please try again later\r\n",
1488       smtp_active_hostname);
1489     return FALSE;
1490     }
1491
1492   /* Determine whether unqualified senders or recipients are permitted
1493   for this host. Unfortunately, we have to do this every time, in order to
1494   set the flags so that they can be inspected when considering qualifying
1495   addresses in the headers. For a site that permits no qualification, this
1496   won't take long, however. */
1497
1498   allow_unqualified_sender =
1499     verify_check_host(&sender_unqualified_hosts) == OK;
1500
1501   allow_unqualified_recipient =
1502     verify_check_host(&recipient_unqualified_hosts) == OK;
1503
1504   /* Determine whether HELO/EHLO is required for this host. The requirement
1505   can be hard or soft. */
1506
1507   helo_required = verify_check_host(&helo_verify_hosts) == OK;
1508   if (!helo_required)
1509     helo_verify = verify_check_host(&helo_try_verify_hosts) == OK;
1510
1511   /* Determine whether this hosts is permitted to send syntactic junk
1512   after a HELO or EHLO command. */
1513
1514   helo_accept_junk = verify_check_host(&helo_accept_junk_hosts) == OK;
1515   }
1516
1517 /* For batch SMTP input we are now done. */
1518
1519 if (smtp_batched_input) return TRUE;
1520
1521 /* Run the ACL if it exists */
1522
1523 if (acl_smtp_connect != NULL)
1524   {
1525   int rc;
1526   uschar *user_msg, *log_msg;
1527   smtp_data = US"in \"connect\" ACL";    /* For logged failure message */
1528   rc = acl_check(ACL_WHERE_CONNECT, US"", acl_smtp_connect, &user_msg,
1529     &log_msg);
1530   if (rc != OK)
1531     {
1532     (void)smtp_handle_acl_fail(ACL_WHERE_CONNECT, rc, user_msg, log_msg);
1533     return FALSE;
1534     }
1535   }
1536
1537 /* Output the initial message for a two-way SMTP connection. It may contain
1538 newlines, which then cause a multi-line response to be given. */
1539
1540 s = expand_string(smtp_banner);
1541 if (s == NULL)
1542   log_write(0, LOG_MAIN|LOG_PANIC_DIE, "Expansion of \"%s\" (smtp_banner) "
1543     "failed: %s", smtp_banner, expand_string_message);
1544
1545 /* Remove any terminating newlines; might as well remove trailing space too */
1546
1547 p = s + Ustrlen(s);
1548 while (p > s && isspace(p[-1])) p--;
1549 *p = 0;
1550
1551 /* It seems that CC:Mail is braindead, and assumes that the greeting message
1552 is all contained in a single IP packet. The original code wrote out the
1553 greeting using several calls to fprint/fputc, and on busy servers this could
1554 cause it to be split over more than one packet - which caused CC:Mail to fall
1555 over when it got the second part of the greeting after sending its first
1556 command. Sigh. To try to avoid this, build the complete greeting message
1557 first, and output it in one fell swoop. This gives a better chance of it
1558 ending up as a single packet. */
1559
1560 ss = store_get(size);
1561 ptr = 0;
1562
1563 p = s;
1564 do       /* At least once, in case we have an empty string */
1565   {
1566   int len;
1567   uschar *linebreak = Ustrchr(p, '\n');
1568   if (linebreak == NULL)
1569     {
1570     len = Ustrlen(p);
1571     ss = string_cat(ss, &size, &ptr, US"220 ", 4);
1572     }
1573   else
1574     {
1575     len = linebreak - p;
1576     ss = string_cat(ss, &size, &ptr, US"220-", 4);
1577     }
1578   ss = string_cat(ss, &size, &ptr, p, len);
1579   ss = string_cat(ss, &size, &ptr, US"\r\n", 2);
1580   p += len;
1581   if (linebreak != NULL) p++;
1582   }
1583 while (*p != 0);
1584
1585 ss[ptr] = 0;  /* string_cat leaves room for this */
1586
1587 /* Before we write the banner, check that there is no input pending, unless
1588 this synchronisation check is disabled. */
1589
1590 if (smtp_enforce_sync && sender_host_address != NULL && !sender_host_notsocket)
1591   {
1592   fd_set fds;
1593   struct timeval tzero;
1594   tzero.tv_sec = 0;
1595   tzero.tv_usec = 0;
1596   FD_ZERO(&fds);
1597   FD_SET(fileno(smtp_in), &fds);
1598   if (select(fileno(smtp_in) + 1, (SELECT_ARG2_TYPE *)&fds, NULL, NULL,
1599       &tzero) > 0)
1600     {
1601     log_write(0, LOG_MAIN|LOG_REJECT, "SMTP protocol violation: "
1602       "synchronization error (input sent without waiting for greeting): "
1603       "rejected connection from %s", host_and_ident(TRUE));
1604     smtp_printf("554 SMTP synchronization error\r\n");
1605     return FALSE;
1606     }
1607   }
1608
1609 /* Now output the banner */
1610
1611 smtp_printf("%s", ss);
1612 return TRUE;
1613 }
1614
1615
1616
1617
1618
1619 /*************************************************
1620 *     Handle SMTP syntax and protocol errors     *
1621 *************************************************/
1622
1623 /* Write to the log for SMTP syntax errors in incoming commands, if configured
1624 to do so. Then transmit the error response. The return value depends on the
1625 number of syntax and protocol errors in this SMTP session.
1626
1627 Arguments:
1628   type      error type, given as a log flag bit
1629   code      response code; <= 0 means don't send a response
1630   data      data to reflect in the response (can be NULL)
1631   errmess   the error message
1632
1633 Returns:    -1   limit of syntax/protocol errors NOT exceeded
1634             +1   limit of syntax/protocol errors IS exceeded
1635
1636 These values fit in with the values of the "done" variable in the main
1637 processing loop in smtp_setup_msg(). */
1638
1639 static int
1640 synprot_error(int type, int code, uschar *data, uschar *errmess)
1641 {
1642 int yield = -1;
1643
1644 log_write(type, LOG_MAIN, "SMTP %s error in \"%s\" %s %s",
1645   (type == L_smtp_syntax_error)? "syntax" : "protocol",
1646   string_printing(cmd_buffer), host_and_ident(TRUE), errmess);
1647
1648 if (++synprot_error_count > smtp_max_synprot_errors)
1649   {
1650   yield = 1;
1651   log_write(0, LOG_MAIN|LOG_REJECT, "SMTP call from %s dropped: too many "
1652     "syntax or protocol errors (last command was \"%s\")",
1653     host_and_ident(FALSE), cmd_buffer);
1654   }
1655
1656 if (code > 0)
1657   {
1658   smtp_printf("%d%c%s%s%s\r\n", code, (yield == 1)? '-' : ' ',
1659     (data == NULL)? US"" : data, (data == NULL)? US"" : US": ", errmess);
1660   if (yield == 1)
1661     smtp_printf("%d Too many syntax or protocol errors\r\n", code);
1662   }
1663
1664 return yield;
1665 }
1666
1667
1668
1669
1670 /*************************************************
1671 *          Log incomplete transactions           *
1672 *************************************************/
1673
1674 /* This function is called after a transaction has been aborted by RSET, QUIT,
1675 connection drops or other errors. It logs the envelope information received
1676 so far in order to preserve address verification attempts.
1677
1678 Argument:   string to indicate what aborted the transaction
1679 Returns:    nothing
1680 */
1681
1682 static void
1683 incomplete_transaction_log(uschar *what)
1684 {
1685 if (sender_address == NULL ||                 /* No transaction in progress */
1686     (log_write_selector & L_smtp_incomplete_transaction) == 0  /* Not logging */
1687   ) return;
1688
1689 /* Build list of recipients for logging */
1690
1691 if (recipients_count > 0)
1692   {
1693   int i;
1694   raw_recipients = store_get(recipients_count * sizeof(uschar *));
1695   for (i = 0; i < recipients_count; i++)
1696     raw_recipients[i] = recipients_list[i].address;
1697   raw_recipients_count = recipients_count;
1698   }
1699
1700 log_write(L_smtp_incomplete_transaction, LOG_MAIN|LOG_SENDER|LOG_RECIPIENTS,
1701   "%s incomplete transaction (%s)", host_and_ident(TRUE), what);
1702 }
1703
1704
1705
1706
1707 /*************************************************
1708 *    Send SMTP response, possibly multiline      *
1709 *************************************************/
1710
1711 /* There are, it seems, broken clients out there that cannot handle multiline
1712 responses. If no_multiline_responses is TRUE (it can be set from an ACL), we
1713 output nothing for non-final calls, and only the first line for anything else.
1714
1715 Arguments:
1716   code          SMTP code
1717   final         FALSE if the last line isn't the final line
1718   msg           message text, possibly containing newlines
1719
1720 Returns:        nothing
1721 */
1722
1723 void
1724 smtp_respond(int code, BOOL final, uschar *msg)
1725 {
1726 if (!final && no_multiline_responses) return;
1727
1728 for (;;)
1729   {
1730   uschar *nl = Ustrchr(msg, '\n');
1731   if (nl == NULL)
1732     {
1733     smtp_printf("%d%c%s\r\n", code, final? ' ':'-', msg);
1734     return;
1735     }
1736   else if (nl[1] == 0 || no_multiline_responses)
1737     {
1738     smtp_printf("%d%c%.*s\r\n", code, final? ' ':'-', (int)(nl - msg), msg);
1739     return;
1740     }
1741   else
1742     {
1743     smtp_printf("%d-%.*s\r\n", code, (int)(nl - msg), msg);
1744     msg = nl + 1;
1745     while (isspace(*msg)) msg++;
1746     }
1747   }
1748 }
1749
1750
1751
1752
1753 /*************************************************
1754 *           Handle an ACL failure                *
1755 *************************************************/
1756
1757 /* This function is called when acl_check() fails. As well as calls from within
1758 this module, it is called from receive.c for an ACL after DATA. It sorts out
1759 logging the incident, and sets up the error response. A message containing
1760 newlines is turned into a multiline SMTP response, but for logging, only the
1761 first line is used.
1762
1763 There's a table of the response codes to use in globals.c, along with the table
1764 of names. VFRY is special. Despite RFC1123 it defaults disabled in Exim.
1765 However, discussion in connection with RFC 821bis (aka RFC 2821) has concluded
1766 that the response should be 252 in the disabled state, because there are broken
1767 clients that try VRFY before RCPT. A 5xx response should be given only when the
1768 address is positively known to be undeliverable. Sigh. Also, for ETRN, 458 is
1769 given on refusal, and for AUTH, 503.
1770
1771 Arguments:
1772   where      where the ACL was called from
1773   rc         the failure code
1774   user_msg   a message that can be included in an SMTP response
1775   log_msg    a message for logging
1776
1777 Returns:     0 in most cases
1778              2 if the failure code was FAIL_DROP, in which case the
1779                SMTP connection should be dropped (this value fits with the
1780                "done" variable in smtp_setup_msg() below)
1781 */
1782
1783 int
1784 smtp_handle_acl_fail(int where, int rc, uschar *user_msg, uschar *log_msg)
1785 {
1786 int code = acl_wherecodes[where];
1787 BOOL drop = rc == FAIL_DROP;
1788 uschar *lognl;
1789 uschar *sender_info = US"";
1790 uschar *what = (where == ACL_WHERE_PREDATA)? US"DATA" :
1791 #ifdef WITH_CONTENT_SCAN
1792                (where == ACL_WHERE_MIME)? US"during MIME ACL checks" :
1793 #endif
1794                (where == ACL_WHERE_DATA)? US"after DATA" :
1795   string_sprintf("%s %s", acl_wherenames[where], smtp_data);
1796
1797 if (drop) rc = FAIL;
1798
1799 /* We used to have sender_address here; however, there was a bug that was not
1800 updating sender_address after a rewrite during a verify. When this bug was
1801 fixed, sender_address at this point became the rewritten address. I'm not sure
1802 this is what should be logged, so I've changed to logging the unrewritten
1803 address to retain backward compatibility. */
1804
1805 #ifndef WITH_CONTENT_SCAN
1806 if (where == ACL_WHERE_RCPT || where == ACL_WHERE_DATA)
1807 #else
1808 if (where == ACL_WHERE_RCPT || where == ACL_WHERE_DATA || where == ACL_WHERE_MIME)
1809 #endif
1810   {
1811   sender_info = string_sprintf("F=<%s> ", (sender_address_unrewritten != NULL)?
1812     sender_address_unrewritten : sender_address);
1813   }
1814
1815 /* If there's been a sender verification failure with a specific message, and
1816 we have not sent a response about it yet, do so now, as a preliminary line for
1817 failures, but not defers. However, log it in both cases. */
1818
1819 if (sender_verified_failed != NULL &&
1820     !testflag(sender_verified_failed, af_sverify_told))
1821   {
1822   setflag(sender_verified_failed, af_sverify_told);
1823
1824   log_write(0, LOG_MAIN|LOG_REJECT, "%s sender verify %s for <%s>%s",
1825     host_and_ident(TRUE),
1826     ((sender_verified_failed->special_action & 255) == DEFER)? "defer" : "fail",
1827     sender_verified_failed->address,
1828     (sender_verified_failed->message == NULL)? US"" :
1829     string_sprintf(": %s", sender_verified_failed->message));
1830
1831   if (rc == FAIL && sender_verified_failed->user_message != NULL)
1832     smtp_respond(code, FALSE, string_sprintf(
1833         testflag(sender_verified_failed, af_verify_pmfail)?
1834           "Postmaster verification failed while checking <%s>\n%s\n"
1835           "Several RFCs state that you are required to have a postmaster\n"
1836           "mailbox for each mail domain. This host does not accept mail\n"
1837           "from domains whose servers reject the postmaster address."
1838           :
1839         testflag(sender_verified_failed, af_verify_nsfail)?
1840           "Callback setup failed while verifying <%s>\n%s\n"
1841           "The initial connection, or a HELO or MAIL FROM:<> command was\n"
1842           "rejected. Refusing MAIL FROM:<> does not help fight spam, disregards\n"
1843           "RFC requirements, and stops you from receiving standard bounce\n"
1844           "messages. This host does not accept mail from domains whose servers\n"
1845           "refuse bounces."
1846           :
1847           "Verification failed for <%s>\n%s",
1848         sender_verified_failed->address,
1849         sender_verified_failed->user_message));
1850   }
1851
1852 /* Sort out text for logging */
1853
1854 log_msg = (log_msg == NULL)? US"" : string_sprintf(": %s", log_msg);
1855 lognl = Ustrchr(log_msg, '\n');
1856 if (lognl != NULL) *lognl = 0;
1857
1858 /* Send permanent failure response to the command, but the code used isn't
1859 always a 5xx one - see comments at the start of this function. If the original
1860 rc was FAIL_DROP we drop the connection and yield 2. */
1861
1862 if (rc == FAIL) smtp_respond(code, TRUE, (user_msg == NULL)?
1863   US"Administrative prohibition" : user_msg);
1864
1865 /* Send temporary failure response to the command. Don't give any details,
1866 unless acl_temp_details is set. This is TRUE for a callout defer, a "defer"
1867 verb, and for a header verify when smtp_return_error_details is set.
1868
1869 This conditional logic is all somewhat of a mess because of the odd
1870 interactions between temp_details and return_error_details. One day it should
1871 be re-implemented in a tidier fashion. */
1872
1873 else
1874   {
1875   if (acl_temp_details && user_msg != NULL)
1876     {
1877     if (smtp_return_error_details &&
1878         sender_verified_failed != NULL &&
1879         sender_verified_failed->message != NULL)
1880       {
1881       smtp_respond(451, FALSE, sender_verified_failed->message);
1882       }
1883     smtp_respond(451, TRUE, user_msg);
1884     }
1885   else
1886     smtp_printf("451 Temporary local problem - please try later\r\n");
1887   }
1888
1889 /* Log the incident. If the connection is not forcibly to be dropped, return 0.
1890 Otherwise, log why it is closing if required and return 2.  */
1891
1892 log_write(0, LOG_MAIN|LOG_REJECT, "%s %s%srejected %s%s",
1893   host_and_ident(TRUE),
1894   sender_info, (rc == FAIL)? US"" : US"temporarily ", what, log_msg);
1895
1896 if (!drop) return 0;
1897
1898 log_write(L_smtp_connection, LOG_MAIN, "%s closed by DROP in ACL",
1899   smtp_get_connection_info());
1900 return 2;
1901 }
1902
1903
1904
1905
1906 /*************************************************
1907 *       Initialize for SMTP incoming message     *
1908 *************************************************/
1909
1910 /* This function conducts the initial dialogue at the start of an incoming SMTP
1911 message, and builds a list of recipients. However, if the incoming message
1912 is part of a batch (-bS option) a separate function is called since it would
1913 be messy having tests splattered about all over this function. This function
1914 therefore handles the case where interaction is occurring. The input and output
1915 files are set up in smtp_in and smtp_out.
1916
1917 The global recipients_list is set to point to a vector of recipient_item
1918 blocks, whose number is given by recipients_count. This is extended by the
1919 receive_add_recipient() function. The global variable sender_address is set to
1920 the sender's address. The yield is +1 if a message has been successfully
1921 started, 0 if a QUIT command was encountered or the connection was refused from
1922 the particular host, or -1 if the connection was lost.
1923
1924 Argument: none
1925
1926 Returns:  > 0 message successfully started (reached DATA)
1927           = 0 QUIT read or end of file reached or call refused
1928           < 0 lost connection
1929 */
1930
1931 int
1932 smtp_setup_msg(void)
1933 {
1934 int done = 0;
1935 BOOL toomany = FALSE;
1936 BOOL discarded = FALSE;
1937 BOOL last_was_rej_mail = FALSE;
1938 BOOL last_was_rcpt = FALSE;
1939 void *reset_point = store_get(0);
1940
1941 DEBUG(D_receive) debug_printf("smtp_setup_msg entered\n");
1942
1943 /* Reset for start of new message. We allow one RSET not to be counted as a
1944 nonmail command, for those MTAs that insist on sending it between every
1945 message. Ditto for EHLO/HELO and for STARTTLS, to allow for going in and out of
1946 TLS between messages (an Exim client may do this if it has messages queued up
1947 for the host). Note: we do NOT reset AUTH at this point. */
1948
1949 smtp_reset(reset_point);
1950 message_ended = END_NOTSTARTED;
1951
1952 cmd_list[CMD_LIST_RSET].is_mail_cmd = TRUE;
1953 cmd_list[CMD_LIST_HELO].is_mail_cmd = TRUE;
1954 cmd_list[CMD_LIST_EHLO].is_mail_cmd = TRUE;
1955 #ifdef SUPPORT_TLS
1956 cmd_list[CMD_LIST_STARTTLS].is_mail_cmd = TRUE;
1957 #endif
1958
1959 /* Set the local signal handler for SIGTERM - it tries to end off tidily */
1960
1961 os_non_restarting_signal(SIGTERM, command_sigterm_handler);
1962
1963 /* Batched SMTP is handled in a different function. */
1964
1965 if (smtp_batched_input) return smtp_setup_batch_msg();
1966
1967 /* Deal with SMTP commands. This loop is exited by setting done to a POSITIVE
1968 value. The values are 2 larger than the required yield of the function. */
1969
1970 while (done <= 0)
1971   {
1972   uschar **argv;
1973   uschar *etrn_command;
1974   uschar *etrn_serialize_key;
1975   uschar *errmess;
1976   uschar *user_msg, *log_msg;
1977   uschar *recipient = NULL;
1978   uschar *hello = NULL;
1979   uschar *set_id = NULL;
1980   uschar *s, *ss;
1981   BOOL was_rej_mail = FALSE;
1982   BOOL was_rcpt = FALSE;
1983   void (*oldsignal)(int);
1984   pid_t pid;
1985   int start, end, sender_domain, recipient_domain;
1986   int ptr, size, rc;
1987   int c;
1988   auth_instance *au;
1989
1990   switch(smtp_read_command(TRUE))
1991     {
1992     /* The AUTH command is not permitted to occur inside a transaction, and may
1993     occur successfully only once per connection, and then only when we've
1994     advertised it. Actually, that isn't quite true. When TLS is started, all
1995     previous information about a connection must be discarded, so a new AUTH is
1996     permitted at that time.
1997
1998     AUTH is initially labelled as a "nonmail command" so that one occurrence
1999     doesn't get counted. We change the label here so that multiple failing
2000     AUTHS will eventually hit the nonmail threshold. */
2001
2002     case AUTH_CMD:
2003     authentication_failed = TRUE;
2004     cmd_list[CMD_LIST_AUTH].is_mail_cmd = FALSE;
2005
2006     if (!auth_advertised)
2007       {
2008       done = synprot_error(L_smtp_protocol_error, 503, NULL,
2009         US"AUTH command used when not advertised");
2010       break;
2011       }
2012     if (sender_host_authenticated != NULL)
2013       {
2014       done = synprot_error(L_smtp_protocol_error, 503, NULL,
2015         US"already authenticated");
2016       break;
2017       }
2018     if (sender_address != NULL)
2019       {
2020       done = synprot_error(L_smtp_protocol_error, 503, NULL,
2021         US"not permitted in mail transaction");
2022       break;
2023       }
2024
2025     /* Check the ACL */
2026
2027     if (acl_smtp_auth != NULL)
2028       {
2029       rc = acl_check(ACL_WHERE_AUTH, smtp_data, acl_smtp_auth, &user_msg,
2030         &log_msg);
2031       if (rc != OK)
2032         {
2033         done = smtp_handle_acl_fail(ACL_WHERE_AUTH, rc, user_msg, log_msg);
2034         break;
2035         }
2036       }
2037
2038     /* Find the name of the requested authentication mechanism. */
2039
2040     s = smtp_data;
2041     while ((c = *smtp_data) != 0 && !isspace(c))
2042       {
2043       if (!isalnum(c) && c != '-' && c != '_')
2044         {
2045         done = synprot_error(L_smtp_syntax_error, 501, NULL,
2046           US"invalid character in authentication mechanism name");
2047         goto COMMAND_LOOP;
2048         }
2049       smtp_data++;
2050       }
2051
2052     /* If not at the end of the line, we must be at white space. Terminate the
2053     name and move the pointer on to any data that may be present. */
2054
2055     if (*smtp_data != 0)
2056       {
2057       *smtp_data++ = 0;
2058       while (isspace(*smtp_data)) smtp_data++;
2059       }
2060
2061     /* Search for an authentication mechanism which is configured for use
2062     as a server and which has been advertised. */
2063
2064     for (au = auths; au != NULL; au = au->next)
2065       {
2066       if (strcmpic(s, au->public_name) == 0 && au->server &&
2067           au->advertised) break;
2068       }
2069
2070     if (au == NULL)
2071       {
2072       done = synprot_error(L_smtp_protocol_error, 504, NULL,
2073         string_sprintf("%s authentication mechanism not supported", s));
2074       break;
2075       }
2076
2077     /* Run the checking code, passing the remainder of the command
2078     line as data. Initialize $0 empty. The authenticator may set up
2079     other numeric variables. Afterwards, have a go at expanding the set_id
2080     string, even if authentication failed - for bad passwords it can be useful
2081     to log the userid. On success, require set_id to expand and exist, and
2082     put it in authenticated_id. Save this in permanent store, as the working
2083     store gets reset at HELO, RSET, etc. */
2084
2085     expand_nmax = 0;
2086     expand_nlength[0] = 0;   /* $0 contains nothing */
2087
2088     c = (au->info->servercode)(au, smtp_data);
2089     if (au->set_id != NULL) set_id = expand_string(au->set_id);
2090     expand_nmax = -1;        /* Reset numeric variables */
2091
2092     /* For the non-OK cases, set up additional logging data if set_id
2093     is not empty. */
2094
2095     if (c != OK)
2096       {
2097       if (set_id != NULL && *set_id != 0)
2098         set_id = string_sprintf(" (set_id=%s)", set_id);
2099       else set_id = US"";
2100       }
2101
2102     /* Switch on the result */
2103
2104     switch(c)
2105       {
2106       case OK:
2107       if (au->set_id == NULL || set_id != NULL)    /* Complete success */
2108         {
2109         if (set_id != NULL) authenticated_id = string_copy_malloc(set_id);
2110         sender_host_authenticated = au->name;
2111         authentication_failed = FALSE;
2112         received_protocol =
2113           protocols[pextend + pauthed + ((tls_active >= 0)? pcrpted:0)] +
2114             ((sender_host_address != NULL)? pnlocal : 0);
2115         s = ss = US"235 Authentication succeeded";
2116         authenticated_by = au;
2117         break;
2118         }
2119
2120       /* Authentication succeeded, but we failed to expand the set_id string.
2121       Treat this as a temporary error. */
2122
2123       auth_defer_msg = expand_string_message;
2124       /* Fall through */
2125
2126       case DEFER:
2127       s = string_sprintf("435 Unable to authenticate at present%s",
2128         auth_defer_user_msg);
2129       ss = string_sprintf("435 Unable to authenticate at present%s: %s",
2130         set_id, auth_defer_msg);
2131       break;
2132
2133       case BAD64:
2134       s = ss = US"501 Invalid base64 data";
2135       break;
2136
2137       case CANCELLED:
2138       s = ss = US"501 Authentication cancelled";
2139       break;
2140
2141       case UNEXPECTED:
2142       s = ss = US"553 Initial data not expected";
2143       break;
2144
2145       case FAIL:
2146       s = US"535 Incorrect authentication data";
2147       ss = string_sprintf("535 Incorrect authentication data%s", set_id);
2148       break;
2149
2150       default:
2151       s = US"435 Internal error";
2152       ss = string_sprintf("435 Internal error%s: return %d from authentication "
2153         "check", set_id, c);
2154       break;
2155       }
2156
2157     smtp_printf("%s\r\n", s);
2158     if (c != OK)
2159       log_write(0, LOG_MAIN|LOG_REJECT, "%s authenticator failed for %s: %s",
2160         au->name, host_and_ident(FALSE), ss);
2161
2162     break;  /* AUTH_CMD */
2163
2164     /* The HELO/EHLO commands are permitted to appear in the middle of a
2165     session as well as at the beginning. They have the effect of a reset in
2166     addition to their other functions. Their absence at the start cannot be
2167     taken to be an error.
2168
2169     RFC 2821 says:
2170
2171       If the EHLO command is not acceptable to the SMTP server, 501, 500,
2172       or 502 failure replies MUST be returned as appropriate.  The SMTP
2173       server MUST stay in the same state after transmitting these replies
2174       that it was in before the EHLO was received.
2175
2176     Therefore, we do not do the reset until after checking the command for
2177     acceptability. This change was made for Exim release 4.11. Previously
2178     it did the reset first. */
2179
2180     case HELO_CMD:
2181     hello = US"HELO";
2182     esmtp = FALSE;
2183     goto HELO_EHLO;
2184
2185     case EHLO_CMD:
2186     hello = US"EHLO";
2187     esmtp = TRUE;
2188
2189     HELO_EHLO:      /* Common code for HELO and EHLO */
2190     cmd_list[CMD_LIST_HELO].is_mail_cmd = FALSE;
2191     cmd_list[CMD_LIST_EHLO].is_mail_cmd = FALSE;
2192
2193     /* Reject the HELO if its argument was invalid or non-existent. A
2194     successful check causes the argument to be saved in malloc store. */
2195
2196     if (!check_helo(smtp_data))
2197       {
2198       smtp_printf("501 Syntactically invalid %s argument(s)\r\n", hello);
2199
2200       log_write(0, LOG_MAIN|LOG_REJECT, "rejected %s from %s: syntactically "
2201         "invalid argument(s): %s", hello, host_and_ident(FALSE),
2202         (*smtp_data == 0)? US"(no argument given)" :
2203                            string_printing(smtp_data));
2204
2205       if (++synprot_error_count > smtp_max_synprot_errors)
2206         {
2207         log_write(0, LOG_MAIN|LOG_REJECT, "SMTP call from %s dropped: too many "
2208           "syntax or protocol errors (last command was \"%s\")",
2209           host_and_ident(FALSE), cmd_buffer);
2210         done = 1;
2211         }
2212
2213       break;
2214       }
2215
2216     /* If sender_host_unknown is true, we have got here via the -bs interface,
2217     not called from inetd. Otherwise, we are running an IP connection and the
2218     host address will be set. If the helo name is the primary name of this
2219     host and we haven't done a reverse lookup, force one now. If helo_required
2220     is set, ensure that the HELO name matches the actual host. If helo_verify
2221     is set, do the same check, but softly. */
2222
2223     if (!sender_host_unknown)
2224       {
2225       BOOL old_helo_verified = helo_verified;
2226       uschar *p = smtp_data;
2227
2228       while (*p != 0 && !isspace(*p)) { *p = tolower(*p); p++; }
2229       *p = 0;
2230
2231       /* Force a reverse lookup if HELO quoted something in helo_lookup_domains
2232       because otherwise the log can be confusing. */
2233
2234       if (sender_host_name == NULL &&
2235            (deliver_domain = sender_helo_name,  /* set $domain */
2236             match_isinlist(sender_helo_name, &helo_lookup_domains, 0,
2237               &domainlist_anchor, NULL, MCL_DOMAIN, TRUE, NULL)) == OK)
2238         (void)host_name_lookup();
2239
2240       /* Rebuild the fullhost info to include the HELO name (and the real name
2241       if it was looked up.) */
2242
2243       host_build_sender_fullhost();  /* Rebuild */
2244       set_process_info("handling%s incoming connection from %s",
2245         (tls_active >= 0)? " TLS" : "", host_and_ident(FALSE));
2246
2247       /* Verify if configured. This doesn't give much security, but it does
2248       make some people happy to be able to do it. Note that HELO is legitimately
2249       allowed to quote an address literal. Allow for IPv6 ::ffff: literals. */
2250
2251       helo_verified = FALSE;
2252       if (helo_required || helo_verify)
2253         {
2254         BOOL tempfail = FALSE;
2255
2256         HDEBUG(D_receive) debug_printf("verifying %s %s\n", hello,
2257           sender_helo_name);
2258         if (sender_helo_name[0] == '[')
2259           {
2260           helo_verified = Ustrncmp(sender_helo_name+1, sender_host_address,
2261             Ustrlen(sender_host_address)) == 0;
2262
2263           #if HAVE_IPV6
2264           if (!helo_verified)
2265             {
2266             if (strncmpic(sender_host_address, US"::ffff:", 7) == 0)
2267               helo_verified = Ustrncmp(sender_helo_name + 1,
2268                 sender_host_address + 7, Ustrlen(sender_host_address) - 7) == 0;
2269             }
2270           #endif
2271
2272           HDEBUG(D_receive)
2273             { if (helo_verified) debug_printf("matched host address\n"); }
2274           }
2275
2276         /* Do a reverse lookup if one hasn't already given a positive or
2277         negative response. If that fails, or the name doesn't match, try
2278         checking with a forward lookup. */
2279
2280         else
2281           {
2282           if (sender_host_name == NULL && !host_lookup_failed)
2283             tempfail = host_name_lookup() == DEFER;
2284
2285           /* If a host name is known, check it and all its aliases. */
2286
2287           if (sender_host_name != NULL)
2288             {
2289             helo_verified = strcmpic(sender_host_name, sender_helo_name) == 0;
2290
2291             if (helo_verified)
2292               {
2293               HDEBUG(D_receive) debug_printf("matched host name\n");
2294               }
2295             else
2296               {
2297               uschar **aliases = sender_host_aliases;
2298               while (*aliases != NULL)
2299                 {
2300                 helo_verified = strcmpic(*aliases++, sender_helo_name) == 0;
2301                 if (helo_verified) break;
2302                 }
2303               HDEBUG(D_receive)
2304                 {
2305                 if (helo_verified)
2306                   debug_printf("matched alias %s\n", *(--aliases));
2307                 }
2308               }
2309             }
2310
2311           /* Final attempt: try a forward lookup of the helo name */
2312
2313           if (!helo_verified)
2314             {
2315             int rc;
2316             host_item h;
2317             h.name = sender_helo_name;
2318             h.address = NULL;
2319             h.mx = MX_NONE;
2320             h.next = NULL;
2321             HDEBUG(D_receive) debug_printf("getting IP address for %s\n",
2322               sender_helo_name);
2323             rc = host_find_byname(&h, NULL, NULL, TRUE);
2324             if (rc == HOST_FOUND || rc == HOST_FOUND_LOCAL)
2325               {
2326               host_item *hh = &h;
2327               while (hh != NULL)
2328                 {
2329                 if (Ustrcmp(hh->address, sender_host_address) == 0)
2330                   {
2331                   helo_verified = TRUE;
2332                   HDEBUG(D_receive)
2333                     debug_printf("IP address for %s matches calling address\n",
2334                       sender_helo_name);
2335                   break;
2336                   }
2337                 hh = hh->next;
2338                 }
2339               }
2340             }
2341           }
2342
2343         /* Verification failed. A temporary lookup failure gives a temporary
2344         error. */
2345
2346         if (!helo_verified)
2347           {
2348           if (helo_required)
2349             {
2350             smtp_printf("%d %s argument does not match calling host\r\n",
2351               tempfail? 451 : 550, hello);
2352             log_write(0, LOG_MAIN|LOG_REJECT, "%srejected \"%s %s\" from %s",
2353               tempfail? "temporarily " : "",
2354               hello, sender_helo_name, host_and_ident(FALSE));
2355             helo_verified = old_helo_verified;
2356             break;                   /* End of HELO/EHLO processing */
2357             }
2358           HDEBUG(D_all) debug_printf("%s verification failed but host is in "
2359             "helo_try_verify_hosts\n", hello);
2360           }
2361         }
2362       }
2363
2364 #ifdef EXPERIMENTAL_SPF
2365     /* set up SPF context */
2366     spf_init(sender_helo_name, sender_host_address);
2367 #endif
2368
2369     /* Apply an ACL check if one is defined */
2370
2371     if (acl_smtp_helo != NULL)
2372       {
2373       rc = acl_check(ACL_WHERE_HELO, smtp_data, acl_smtp_helo, &user_msg,
2374         &log_msg);
2375       if (rc != OK)
2376         {
2377         done = smtp_handle_acl_fail(ACL_WHERE_HELO, rc, user_msg, log_msg);
2378         sender_helo_name = NULL;
2379         host_build_sender_fullhost();  /* Rebuild */
2380         break;
2381         }
2382       }
2383
2384     /* The EHLO/HELO command is acceptable. Reset the protocol and the state,
2385     abandoning any previous message. */
2386
2387     received_protocol = (esmtp?
2388       protocols[pextend +
2389         ((sender_host_authenticated != NULL)? pauthed : 0) +
2390         ((tls_active >= 0)? pcrpted : 0)]
2391       :
2392       protocols[pnormal + ((tls_active >= 0)? pcrpted : 0)])
2393       +
2394       ((sender_host_address != NULL)? pnlocal : 0);
2395
2396     smtp_reset(reset_point);
2397     toomany = FALSE;
2398
2399     /* Generate an OK reply, including the ident if present, and also
2400     the IP address if present. Reflecting back the ident is intended
2401     as a deterrent to mail forgers. For maximum efficiency, and also
2402     because some broken systems expect each response to be in a single
2403     packet, arrange that it is sent in one write(). */
2404
2405     auth_advertised = FALSE;
2406     pipelining_advertised = FALSE;
2407     #ifdef SUPPORT_TLS
2408     tls_advertised = FALSE;
2409     #endif
2410
2411     s = string_sprintf("250 %s Hello %s%s%s",
2412       smtp_active_hostname,
2413       (sender_ident == NULL)?  US"" : sender_ident,
2414       (sender_ident == NULL)?  US"" : US" at ",
2415       (sender_host_name == NULL)? sender_helo_name : sender_host_name);
2416
2417     ptr = Ustrlen(s);
2418     size = ptr + 1;
2419
2420     if (sender_host_address != NULL)
2421       {
2422       s = string_cat(s, &size, &ptr, US" [", 2);
2423       s = string_cat(s, &size, &ptr, sender_host_address,
2424         Ustrlen(sender_host_address));
2425       s = string_cat(s, &size, &ptr, US"]", 1);
2426       }
2427
2428     s = string_cat(s, &size, &ptr, US"\r\n", 2);
2429
2430     /* If we received EHLO, we must create a multiline response which includes
2431     the functions supported. */
2432
2433     if (esmtp)
2434       {
2435       s[3] = '-';
2436
2437       /* I'm not entirely happy with this, as an MTA is supposed to check
2438       that it has enough room to accept a message of maximum size before
2439       it sends this. However, there seems little point in not sending it.
2440       The actual size check happens later at MAIL FROM time. By postponing it
2441       till then, VRFY and EXPN can be used after EHLO when space is short. */
2442
2443       if (thismessage_size_limit > 0)
2444         {
2445         sprintf(CS big_buffer, "250-SIZE %d\r\n", thismessage_size_limit);
2446         s = string_cat(s, &size, &ptr, big_buffer, Ustrlen(big_buffer));
2447         }
2448       else
2449         {
2450         s = string_cat(s, &size, &ptr, US"250-SIZE\r\n", 10);
2451         }
2452
2453       /* Exim does not do protocol conversion or data conversion. It is 8-bit
2454       clean; if it has an 8-bit character in its hand, it just sends it. It
2455       cannot therefore specify 8BITMIME and remain consistent with the RFCs.
2456       However, some users want this option simply in order to stop MUAs
2457       mangling messages that contain top-bit-set characters. It is therefore
2458       provided as an option. */
2459
2460       if (accept_8bitmime)
2461         s = string_cat(s, &size, &ptr, US"250-8BITMIME\r\n", 14);
2462
2463       /* Advertise ETRN if there's an ACL checking whether a host is
2464       permitted to issue it; a check is made when any host actually tries. */
2465
2466       if (acl_smtp_etrn != NULL)
2467         {
2468         s = string_cat(s, &size, &ptr, US"250-ETRN\r\n", 10);
2469         }
2470
2471       /* Advertise EXPN if there's an ACL checking whether a host is
2472       permitted to issue it; a check is made when any host actually tries. */
2473
2474       if (acl_smtp_expn != NULL)
2475         {
2476         s = string_cat(s, &size, &ptr, US"250-EXPN\r\n", 10);
2477         }
2478
2479       /* Exim is quite happy with pipelining, so let the other end know that
2480       it is safe to use it, unless advertising is disabled. */
2481
2482       if (verify_check_host(&pipelining_advertise_hosts) == OK)
2483         {
2484         s = string_cat(s, &size, &ptr, US"250-PIPELINING\r\n", 16);
2485         sync_cmd_limit = NON_SYNC_CMD_PIPELINING;
2486         pipelining_advertised = TRUE;
2487         }
2488
2489       /* If any server authentication mechanisms are configured, advertise
2490       them if the current host is in auth_advertise_hosts. The problem with
2491       advertising always is that some clients then require users to
2492       authenticate (and aren't configurable otherwise) even though it may not
2493       be necessary (e.g. if the host is in host_accept_relay).
2494
2495       RFC 2222 states that SASL mechanism names contain only upper case
2496       letters, so output the names in upper case, though we actually recognize
2497       them in either case in the AUTH command. */
2498
2499       if (auths != NULL)
2500         {
2501         if (verify_check_host(&auth_advertise_hosts) == OK)
2502           {
2503           auth_instance *au;
2504           BOOL first = TRUE;
2505           for (au = auths; au != NULL; au = au->next)
2506             {
2507             if (au->server && (au->advertise_condition == NULL ||
2508                 expand_check_condition(au->advertise_condition, au->name,
2509                 US"authenticator")))
2510               {
2511               int saveptr;
2512               if (first)
2513                 {
2514                 s = string_cat(s, &size, &ptr, US"250-AUTH", 8);
2515                 first = FALSE;
2516                 auth_advertised = TRUE;
2517                 }
2518               saveptr = ptr;
2519               s = string_cat(s, &size, &ptr, US" ", 1);
2520               s = string_cat(s, &size, &ptr, au->public_name,
2521                 Ustrlen(au->public_name));
2522               while (++saveptr < ptr) s[saveptr] = toupper(s[saveptr]);
2523               au->advertised = TRUE;
2524               }
2525             else au->advertised = FALSE;
2526             }
2527           if (!first) s = string_cat(s, &size, &ptr, US"\r\n", 2);
2528           }
2529         }
2530
2531       /* Advertise TLS (Transport Level Security) aka SSL (Secure Socket Layer)
2532       if it has been included in the binary, and the host matches
2533       tls_advertise_hosts. We must *not* advertise if we are already in a
2534       secure connection. */
2535
2536       #ifdef SUPPORT_TLS
2537       if (tls_active < 0 &&
2538           verify_check_host(&tls_advertise_hosts) != FAIL)
2539         {
2540         s = string_cat(s, &size, &ptr, US"250-STARTTLS\r\n", 14);
2541         tls_advertised = TRUE;
2542         }
2543       #endif
2544
2545       /* Finish off the multiline reply with one that is always available. */
2546
2547       s = string_cat(s, &size, &ptr, US"250 HELP\r\n", 10);
2548       }
2549
2550     /* Terminate the string (for debug), write it, and note that HELO/EHLO
2551     has been seen. */
2552
2553     s[ptr] = 0;
2554
2555     #ifdef SUPPORT_TLS
2556     if (tls_active >= 0) (void)tls_write(s, ptr); else
2557     #endif
2558
2559     fwrite(s, 1, ptr, smtp_out);
2560     DEBUG(D_receive) debug_printf("SMTP>> %s", s);
2561     helo_seen = TRUE;
2562     break;   /* HELO/EHLO */
2563
2564
2565     /* The MAIL command requires an address as an operand. All we do
2566     here is to parse it for syntactic correctness. The form "<>" is
2567     a special case which converts into an empty string. The start/end
2568     pointers in the original are not used further for this address, as
2569     it is the canonical extracted address which is all that is kept. */
2570
2571     case MAIL_CMD:
2572     smtp_mailcmd_count++;              /* Count for limit and ratelimit */
2573     was_rej_mail = TRUE;               /* Reset if accepted */
2574
2575     if (helo_required && !helo_seen)
2576       {
2577       smtp_printf("503 HELO or EHLO required\r\n");
2578       log_write(0, LOG_MAIN|LOG_REJECT, "rejected MAIL from %s: no "
2579         "HELO/EHLO given", host_and_ident(FALSE));
2580       break;
2581       }
2582
2583     if (sender_address != NULL)
2584       {
2585       done = synprot_error(L_smtp_protocol_error, 503, NULL,
2586         US"sender already given");
2587       break;
2588       }
2589
2590     if (smtp_data[0] == 0)
2591       {
2592       done = synprot_error(L_smtp_protocol_error, 501, NULL,
2593         US"MAIL must have an address operand");
2594       break;
2595       }
2596
2597     /* Check to see if the limit for messages per connection would be
2598     exceeded by accepting further messages. */
2599
2600     if (smtp_accept_max_per_connection > 0 &&
2601         smtp_mailcmd_count > smtp_accept_max_per_connection)
2602       {
2603       smtp_printf("421 too many messages in this connection\r\n");
2604       log_write(0, LOG_MAIN|LOG_REJECT, "rejected MAIL command %s: too many "
2605         "messages in one connection", host_and_ident(TRUE));
2606       break;
2607       }
2608
2609     /* Reset for start of message - even if this is going to fail, we
2610     obviously need to throw away any previous data. */
2611
2612     smtp_reset(reset_point);
2613     toomany = FALSE;
2614     sender_data = recipient_data = NULL;
2615
2616     /* Loop, checking for ESMTP additions to the MAIL FROM command. */
2617
2618     if (esmtp) for(;;)
2619       {
2620       uschar *name, *value, *end;
2621       unsigned long int size;
2622
2623       if (!extract_option(&name, &value)) break;
2624
2625       /* Handle SIZE= by reading the value. We don't do the check till later,
2626       in order to be able to log the sender address on failure. */
2627
2628       if (strcmpic(name, US"SIZE") == 0 &&
2629           ((size = (int)Ustrtoul(value, &end, 10)), *end == 0))
2630         {
2631         if ((size == ULONG_MAX && errno == ERANGE) || size > INT_MAX)
2632           size = INT_MAX;
2633         message_size = (int)size;
2634         }
2635
2636       /* If this session was initiated with EHLO and accept_8bitmime is set,
2637       Exim will have indicated that it supports the BODY=8BITMIME option. In
2638       fact, it does not support this according to the RFCs, in that it does not
2639       take any special action for forwarding messages containing 8-bit
2640       characters. That is why accept_8bitmime is not the default setting, but
2641       some sites want the action that is provided. We recognize both "8BITMIME"
2642       and "7BIT" as body types, but take no action. */
2643
2644       else if (accept_8bitmime && strcmpic(name, US"BODY") == 0 &&
2645           (strcmpic(value, US"8BITMIME") == 0 ||
2646            strcmpic(value, US"7BIT") == 0)) {}
2647
2648       /* Handle the AUTH extension. If the value given is not "<>" and either
2649       the ACL says "yes" or there is no ACL but the sending host is
2650       authenticated, we set it up as the authenticated sender. However, if the
2651       authenticator set a condition to be tested, we ignore AUTH on MAIL unless
2652       the condition is met. The value of AUTH is an xtext, which means that +,
2653       = and cntrl chars are coded in hex; however "<>" is unaffected by this
2654       coding. */
2655
2656       else if (strcmpic(name, US"AUTH") == 0)
2657         {
2658         if (Ustrcmp(value, "<>") != 0)
2659           {
2660           int rc;
2661           uschar *ignore_msg;
2662
2663           if (auth_xtextdecode(value, &authenticated_sender) < 0)
2664             {
2665             /* Put back terminator overrides for error message */
2666             name[-1] = ' ';
2667             value[-1] = '=';
2668             done = synprot_error(L_smtp_syntax_error, 501, NULL,
2669               US"invalid data for AUTH");
2670             goto COMMAND_LOOP;
2671             }
2672
2673           if (acl_smtp_mailauth == NULL)
2674             {
2675             ignore_msg = US"client not authenticated";
2676             rc = (sender_host_authenticated != NULL)? OK : FAIL;
2677             }
2678           else
2679             {
2680             ignore_msg = US"rejected by ACL";
2681             rc = acl_check(ACL_WHERE_MAILAUTH, NULL, acl_smtp_mailauth,
2682               &user_msg, &log_msg);
2683             }
2684
2685           switch (rc)
2686             {
2687             case OK:
2688             if (authenticated_by == NULL ||
2689                 authenticated_by->mail_auth_condition == NULL ||
2690                 expand_check_condition(authenticated_by->mail_auth_condition,
2691                     authenticated_by->name, US"authenticator"))
2692               break;     /* Accept the AUTH */
2693
2694             ignore_msg = US"server_mail_auth_condition failed";
2695             if (authenticated_id != NULL)
2696               ignore_msg = string_sprintf("%s: authenticated ID=\"%s\"",
2697                 ignore_msg, authenticated_id);
2698
2699             /* Fall through */
2700
2701             case FAIL:
2702             authenticated_sender = NULL;
2703             log_write(0, LOG_MAIN, "ignoring AUTH=%s from %s (%s)",
2704               value, host_and_ident(TRUE), ignore_msg);
2705             break;
2706
2707             /* Should only get DEFER or ERROR here. Put back terminator
2708             overrides for error message */
2709
2710             default:
2711             name[-1] = ' ';
2712             value[-1] = '=';
2713             (void)smtp_handle_acl_fail(ACL_WHERE_MAILAUTH, rc, user_msg,
2714               log_msg);
2715             goto COMMAND_LOOP;
2716             }
2717           }
2718         }
2719
2720       /* Unknown option. Stick back the terminator characters and break
2721       the loop. An error for a malformed address will occur. */
2722
2723       else
2724         {
2725         name[-1] = ' ';
2726         value[-1] = '=';
2727         break;
2728         }
2729       }
2730
2731     /* If we have passed the threshold for rate limiting, apply the current
2732     delay, and update it for next time, provided this is a limited host. */
2733
2734     if (smtp_mailcmd_count > smtp_rlm_threshold &&
2735         verify_check_host(&smtp_ratelimit_hosts) == OK)
2736       {
2737       DEBUG(D_receive) debug_printf("rate limit MAIL: delay %.3g sec\n",
2738         smtp_delay_mail/1000.0);
2739       millisleep((int)smtp_delay_mail);
2740       smtp_delay_mail *= smtp_rlm_factor;
2741       if (smtp_delay_mail > (double)smtp_rlm_limit)
2742         smtp_delay_mail = (double)smtp_rlm_limit;
2743       }
2744
2745     /* Now extract the address, first applying any SMTP-time rewriting. The
2746     TRUE flag allows "<>" as a sender address. */
2747
2748     raw_sender = ((rewrite_existflags & rewrite_smtp) != 0)?
2749       rewrite_one(smtp_data, rewrite_smtp, NULL, FALSE, US"",
2750         global_rewrite_rules) : smtp_data;
2751
2752     /* rfc821_domains = TRUE; << no longer needed */
2753     raw_sender =
2754       parse_extract_address(raw_sender, &errmess, &start, &end, &sender_domain,
2755         TRUE);
2756     /* rfc821_domains = FALSE; << no longer needed */
2757
2758     if (raw_sender == NULL)
2759       {
2760       done = synprot_error(L_smtp_syntax_error, 501, smtp_data, errmess);
2761       break;
2762       }
2763
2764     sender_address = raw_sender;
2765
2766     /* If there is a configured size limit for mail, check that this message
2767     doesn't exceed it. The check is postponed to this point so that the sender
2768     can be logged. */
2769
2770     if (thismessage_size_limit > 0 && message_size > thismessage_size_limit)
2771       {
2772       smtp_printf("552 Message size exceeds maximum permitted\r\n");
2773       log_write(L_size_reject,
2774           LOG_MAIN|LOG_REJECT, "rejected MAIL FROM:<%s> %s: "
2775           "message too big: size%s=%d max=%d",
2776           sender_address,
2777           host_and_ident(TRUE),
2778           (message_size == INT_MAX)? ">" : "",
2779           message_size,
2780           thismessage_size_limit);
2781       sender_address = NULL;
2782       break;
2783       }
2784
2785     /* Check there is enough space on the disk unless configured not to.
2786     When smtp_check_spool_space is set, the check is for thismessage_size_limit
2787     plus the current message - i.e. we accept the message only if it won't
2788     reduce the space below the threshold. Add 5000 to the size to allow for
2789     overheads such as the Received: line and storing of recipients, etc.
2790     By putting the check here, even when SIZE is not given, it allow VRFY
2791     and EXPN etc. to be used when space is short. */
2792
2793     if (!receive_check_fs(
2794          (smtp_check_spool_space && message_size >= 0)?
2795             message_size + 5000 : 0))
2796       {
2797       smtp_printf("452 Space shortage, please try later\r\n");
2798       sender_address = NULL;
2799       break;
2800       }
2801
2802     /* If sender_address is unqualified, reject it, unless this is a locally
2803     generated message, or the sending host or net is permitted to send
2804     unqualified addresses - typically local machines behaving as MUAs -
2805     in which case just qualify the address. The flag is set above at the start
2806     of the SMTP connection. */
2807
2808     if (sender_domain == 0 && sender_address[0] != 0)
2809       {
2810       if (allow_unqualified_sender)
2811         {
2812         sender_domain = Ustrlen(sender_address) + 1;
2813         sender_address = rewrite_address_qualify(sender_address, FALSE);
2814         DEBUG(D_receive) debug_printf("unqualified address %s accepted\n",
2815           raw_sender);
2816         }
2817       else
2818         {
2819         smtp_printf("501 %s: sender address must contain a domain\r\n",
2820           smtp_data);
2821         log_write(L_smtp_syntax_error,
2822           LOG_MAIN|LOG_REJECT,
2823           "unqualified sender rejected: <%s> %s%s",
2824           raw_sender,
2825           host_and_ident(TRUE),
2826           host_lookup_msg);
2827         sender_address = NULL;
2828         break;
2829         }
2830       }
2831
2832     /* Apply an ACL check if one is defined, before responding */
2833
2834     rc = (acl_smtp_mail == NULL)? OK :
2835       acl_check(ACL_WHERE_MAIL, NULL, acl_smtp_mail, &user_msg, &log_msg);
2836
2837     if (rc == OK || rc == DISCARD)
2838       {
2839       smtp_printf("250 OK\r\n");
2840       smtp_delay_rcpt = smtp_rlr_base;
2841       recipients_discarded = (rc == DISCARD);
2842       was_rej_mail = FALSE;
2843       }
2844
2845     else
2846       {
2847       done = smtp_handle_acl_fail(ACL_WHERE_MAIL, rc, user_msg, log_msg);
2848       sender_address = NULL;
2849       }
2850     break;
2851
2852
2853     /* The RCPT command requires an address as an operand. All we do
2854     here is to parse it for syntactic correctness. There may be any number
2855     of RCPT commands, specifying multiple senders. We build them all into
2856     a data structure that is in argc/argv format. The start/end values
2857     given by parse_extract_address are not used, as we keep only the
2858     extracted address. */
2859
2860     case RCPT_CMD:
2861     rcpt_count++;
2862     was_rcpt = TRUE;
2863
2864     /* There must be a sender address; if the sender was rejected and
2865     pipelining was advertised, we assume the client was pipelining, and do not
2866     count this as a protocol error. Reset was_rej_mail so that further RCPTs
2867     get the same treatment. */
2868
2869     if (sender_address == NULL)
2870       {
2871       if (pipelining_advertised && last_was_rej_mail)
2872         {
2873         smtp_printf("503 sender not yet given\r\n");
2874         was_rej_mail = TRUE;
2875         }
2876       else
2877         {
2878         done = synprot_error(L_smtp_protocol_error, 503, NULL,
2879           US"sender not yet given");
2880         was_rcpt = FALSE;             /* Not a valid RCPT */
2881         }
2882       rcpt_fail_count++;
2883       break;
2884       }
2885
2886     /* Check for an operand */
2887
2888     if (smtp_data[0] == 0)
2889       {
2890       done = synprot_error(L_smtp_syntax_error, 501, NULL,
2891         US"RCPT must have an address operand");
2892       rcpt_fail_count++;
2893       break;
2894       }
2895
2896     /* Apply SMTP rewriting then extract the working address. Don't allow "<>"
2897     as a recipient address */
2898
2899     recipient = ((rewrite_existflags & rewrite_smtp) != 0)?
2900       rewrite_one(smtp_data, rewrite_smtp, NULL, FALSE, US"",
2901         global_rewrite_rules) : smtp_data;
2902
2903     /* rfc821_domains = TRUE; << no longer needed */
2904     recipient = parse_extract_address(recipient, &errmess, &start, &end,
2905       &recipient_domain, FALSE);
2906     /* rfc821_domains = FALSE; << no longer needed */
2907
2908     if (recipient == NULL)
2909       {
2910       done = synprot_error(L_smtp_syntax_error, 501, smtp_data, errmess);
2911       rcpt_fail_count++;
2912       break;
2913       }
2914
2915     /* If the recipient address is unqualified, reject it, unless this is a
2916     locally generated message. However, unqualified addresses are permitted
2917     from a configured list of hosts and nets - typically when behaving as
2918     MUAs rather than MTAs. Sad that SMTP is used for both types of traffic,
2919     really. The flag is set at the start of the SMTP connection.
2920
2921     RFC 1123 talks about supporting "the reserved mailbox postmaster"; I always
2922     assumed this meant "reserved local part", but the revision of RFC 821 and
2923     friends now makes it absolutely clear that it means *mailbox*. Consequently
2924     we must always qualify this address, regardless. */
2925
2926     if (recipient_domain == 0)
2927       {
2928       if (allow_unqualified_recipient ||
2929           strcmpic(recipient, US"postmaster") == 0)
2930         {
2931         DEBUG(D_receive) debug_printf("unqualified address %s accepted\n",
2932           recipient);
2933         recipient_domain = Ustrlen(recipient) + 1;
2934         recipient = rewrite_address_qualify(recipient, TRUE);
2935         }
2936       else
2937         {
2938         rcpt_fail_count++;
2939         smtp_printf("501 %s: recipient address must contain a domain\r\n",
2940           smtp_data);
2941         log_write(L_smtp_syntax_error,
2942           LOG_MAIN|LOG_REJECT, "unqualified recipient rejected: "
2943           "<%s> %s%s", recipient, host_and_ident(TRUE),
2944           host_lookup_msg);
2945         break;
2946         }
2947       }
2948
2949     /* Check maximum allowed */
2950
2951     if (rcpt_count > recipients_max && recipients_max > 0)
2952       {
2953       if (recipients_max_reject)
2954         {
2955         rcpt_fail_count++;
2956         smtp_printf("552 too many recipients\r\n");
2957         if (!toomany)
2958           log_write(0, LOG_MAIN|LOG_REJECT, "too many recipients: message "
2959             "rejected: sender=<%s> %s", sender_address, host_and_ident(TRUE));
2960         }
2961       else
2962         {
2963         rcpt_defer_count++;
2964         smtp_printf("452 too many recipients\r\n");
2965         if (!toomany)
2966           log_write(0, LOG_MAIN|LOG_REJECT, "too many recipients: excess "
2967             "temporarily rejected: sender=<%s> %s", sender_address,
2968             host_and_ident(TRUE));
2969         }
2970
2971       toomany = TRUE;
2972       break;
2973       }
2974
2975     /* If we have passed the threshold for rate limiting, apply the current
2976     delay, and update it for next time, provided this is a limited host. */
2977
2978     if (rcpt_count > smtp_rlr_threshold &&
2979         verify_check_host(&smtp_ratelimit_hosts) == OK)
2980       {
2981       DEBUG(D_receive) debug_printf("rate limit RCPT: delay %.3g sec\n",
2982         smtp_delay_rcpt/1000.0);
2983       millisleep((int)smtp_delay_rcpt);
2984       smtp_delay_rcpt *= smtp_rlr_factor;
2985       if (smtp_delay_rcpt > (double)smtp_rlr_limit)
2986         smtp_delay_rcpt = (double)smtp_rlr_limit;
2987       }
2988
2989     /* If the MAIL ACL discarded all the recipients, we bypass ACL checking
2990     for them. Otherwise, check the access control list for this recipient. */
2991
2992     rc = recipients_discarded? DISCARD :
2993       acl_check(ACL_WHERE_RCPT, recipient, acl_smtp_rcpt, &user_msg, &log_msg);
2994
2995     /* The ACL was happy */
2996
2997     if (rc == OK)
2998       {
2999       smtp_printf("250 Accepted\r\n");
3000       receive_add_recipient(recipient, -1);
3001       }
3002
3003     /* The recipient was discarded */
3004
3005     else if (rc == DISCARD)
3006       {
3007       smtp_printf("250 Accepted\r\n");
3008       rcpt_fail_count++;
3009       discarded = TRUE;
3010       log_write(0, LOG_MAIN|LOG_REJECT, "%s F=<%s> rejected RCPT %s: "
3011         "discarded by %s ACL%s%s", host_and_ident(TRUE),
3012         (sender_address_unrewritten != NULL)?
3013         sender_address_unrewritten : sender_address,
3014         smtp_data, recipients_discarded? "MAIL" : "RCPT",
3015         (log_msg == NULL)? US"" : US": ",
3016         (log_msg == NULL)? US"" : log_msg);
3017       }
3018
3019     /* Either the ACL failed the address, or it was deferred. */
3020
3021     else
3022       {
3023       if (rc == FAIL) rcpt_fail_count++; else rcpt_defer_count++;
3024       done = smtp_handle_acl_fail(ACL_WHERE_RCPT, rc, user_msg, log_msg);
3025       }
3026     break;
3027
3028
3029     /* The DATA command is legal only if it follows successful MAIL FROM
3030     and RCPT TO commands. However, if pipelining is advertised, a bad DATA is
3031     not counted as a protocol error if it follows RCPT (which must have been
3032     rejected if there are no recipients.) This function is complete when a
3033     valid DATA command is encountered.
3034
3035     Note concerning the code used: RFC 2821 says this:
3036
3037      -  If there was no MAIL, or no RCPT, command, or all such commands
3038         were rejected, the server MAY return a "command out of sequence"
3039         (503) or "no valid recipients" (554) reply in response to the
3040         DATA command.
3041
3042     The example in the pipelining RFC 2920 uses 554, but I use 503 here
3043     because it is the same whether pipelining is in use or not. */
3044
3045     case DATA_CMD:
3046     if (!discarded && recipients_count <= 0)
3047       {
3048       if (pipelining_advertised && last_was_rcpt)
3049         smtp_printf("503 valid RCPT command must precede DATA\r\n");
3050       else
3051         done = synprot_error(L_smtp_protocol_error, 503, NULL,
3052           US"valid RCPT command must precede DATA");
3053       break;
3054       }
3055
3056     if (toomany && recipients_max_reject)
3057       {
3058       sender_address = NULL;  /* This will allow a new MAIL without RSET */
3059       sender_address_unrewritten = NULL;
3060       smtp_printf("554 Too many recipients\r\n");
3061       break;
3062       }
3063
3064     if (acl_smtp_predata == NULL) rc = OK; else
3065       {
3066       enable_dollar_recipients = TRUE;
3067       rc = acl_check(ACL_WHERE_PREDATA, NULL, acl_smtp_predata, &user_msg,
3068         &log_msg);
3069       enable_dollar_recipients = FALSE;
3070       }
3071
3072     if (rc == OK)
3073       {
3074       smtp_printf("354 Enter message, ending with \".\" on a line by itself\r\n");
3075       done = 3;
3076       message_ended = END_NOTENDED;   /* Indicate in middle of data */
3077       }
3078
3079     /* Either the ACL failed the address, or it was deferred. */
3080
3081     else
3082       done = smtp_handle_acl_fail(ACL_WHERE_PREDATA, rc, user_msg, log_msg);
3083
3084     break;
3085
3086
3087     case VRFY_CMD:
3088     rc = acl_check(ACL_WHERE_VRFY, smtp_data, acl_smtp_vrfy, &user_msg,
3089       &log_msg);
3090     if (rc != OK)
3091       done = smtp_handle_acl_fail(ACL_WHERE_VRFY, rc, user_msg, log_msg);
3092     else
3093       {
3094       uschar *address;
3095       uschar *s = NULL;
3096
3097       /* rfc821_domains = TRUE; << no longer needed */
3098       address = parse_extract_address(smtp_data, &errmess, &start, &end,
3099         &recipient_domain, FALSE);
3100       /* rfc821_domains = FALSE; << no longer needed */
3101
3102       if (address == NULL)
3103         s = string_sprintf("501 %s", errmess);
3104       else
3105         {
3106         address_item *addr = deliver_make_addr(address, FALSE);
3107         switch(verify_address(addr, NULL, vopt_is_recipient | vopt_qualify, -1,
3108                -1, -1, NULL, NULL, NULL))
3109           {
3110           case OK:
3111           s = string_sprintf("250 <%s> is deliverable", address);
3112           break;
3113
3114           case DEFER:
3115           s = (addr->message != NULL)?
3116             string_sprintf("451 <%s> %s", address, addr->message) :
3117             string_sprintf("451 Cannot resolve <%s> at this time", address);
3118           break;
3119
3120           case FAIL:
3121           s = (addr->message != NULL)?
3122             string_sprintf("550 <%s> %s", address, addr->message) :
3123             string_sprintf("550 <%s> is not deliverable", address);
3124           log_write(0, LOG_MAIN, "VRFY failed for %s %s",
3125             smtp_data, host_and_ident(TRUE));
3126           break;
3127           }
3128         }
3129
3130       smtp_printf("%s\r\n", s);
3131       }
3132     break;
3133
3134
3135     case EXPN_CMD:
3136     rc = acl_check(ACL_WHERE_EXPN, smtp_data, acl_smtp_expn, &user_msg,
3137       &log_msg);
3138     if (rc != OK)
3139       done = smtp_handle_acl_fail(ACL_WHERE_EXPN, rc, user_msg, log_msg);
3140     else
3141       {
3142       BOOL save_log_testing_mode = log_testing_mode;
3143       address_test_mode = log_testing_mode = TRUE;
3144       (void) verify_address(deliver_make_addr(smtp_data, FALSE), smtp_out,
3145         vopt_is_recipient | vopt_qualify | vopt_expn, -1, -1, -1, NULL, NULL,
3146         NULL);
3147       address_test_mode = FALSE;
3148       log_testing_mode = save_log_testing_mode;    /* true for -bh */
3149       }
3150     break;
3151
3152
3153     #ifdef SUPPORT_TLS
3154
3155     case STARTTLS_CMD:
3156     if (!tls_advertised)
3157       {
3158       done = synprot_error(L_smtp_protocol_error, 503, NULL,
3159         US"STARTTLS command used when not advertised");
3160       break;
3161       }
3162
3163     /* Apply an ACL check if one is defined */
3164
3165     if (acl_smtp_starttls != NULL)
3166       {
3167       rc = acl_check(ACL_WHERE_STARTTLS, NULL, acl_smtp_starttls, &user_msg,
3168         &log_msg);
3169       if (rc != OK)
3170         {
3171         done = smtp_handle_acl_fail(ACL_WHERE_STARTTLS, rc, user_msg, log_msg);
3172         break;
3173         }
3174       }
3175
3176     /* RFC 2487 is not clear on when this command may be sent, though it
3177     does state that all information previously obtained from the client
3178     must be discarded if a TLS session is started. It seems reasonble to
3179     do an implied RSET when STARTTLS is received. */
3180
3181     incomplete_transaction_log(US"STARTTLS");
3182     smtp_reset(reset_point);
3183     toomany = FALSE;
3184     cmd_list[CMD_LIST_STARTTLS].is_mail_cmd = FALSE;
3185
3186     /* Attempt to start up a TLS session, and if successful, discard all
3187     knowledge that was obtained previously. At least, that's what the RFC says,
3188     and that's what happens by default. However, in order to work round YAEB,
3189     there is an option to remember the esmtp state. Sigh.
3190
3191     We must allow for an extra EHLO command and an extra AUTH command after
3192     STARTTLS that don't add to the nonmail command count. */
3193
3194     if ((rc = tls_server_start(tls_require_ciphers)) == OK)
3195       {
3196       if (!tls_remember_esmtp)
3197         helo_seen = esmtp = auth_advertised = pipelining_advertised = FALSE;
3198       cmd_list[CMD_LIST_EHLO].is_mail_cmd = TRUE;
3199       cmd_list[CMD_LIST_AUTH].is_mail_cmd = TRUE;
3200       if (sender_helo_name != NULL)
3201         {
3202         store_free(sender_helo_name);
3203         sender_helo_name = NULL;
3204         host_build_sender_fullhost();  /* Rebuild */
3205         set_process_info("handling incoming TLS connection from %s",
3206           host_and_ident(FALSE));
3207         }
3208       received_protocol = (esmtp?
3209         protocols[pextend + pcrpted +
3210           ((sender_host_authenticated != NULL)? pauthed : 0)]
3211         :
3212         protocols[pnormal + pcrpted])
3213         +
3214         ((sender_host_address != NULL)? pnlocal : 0);
3215
3216       sender_host_authenticated = NULL;
3217       authenticated_id = NULL;
3218       sync_cmd_limit = NON_SYNC_CMD_NON_PIPELINING;
3219       DEBUG(D_tls) debug_printf("TLS active\n");
3220       break;     /* Successful STARTTLS */
3221       }
3222
3223     /* Some local configuration problem was discovered before actually trying
3224     to do a TLS handshake; give a temporary error. */
3225
3226     else if (rc == DEFER)
3227       {
3228       smtp_printf("454 TLS currently unavailable\r\n");
3229       break;
3230       }
3231
3232     /* Hard failure. Reject everything except QUIT or closed connection. One
3233     cause for failure is a nested STARTTLS, in which case tls_active remains
3234     set, but we must still reject all incoming commands. */
3235
3236     DEBUG(D_tls) debug_printf("TLS failed to start\n");
3237     while (done <= 0)
3238       {
3239       switch(smtp_read_command(FALSE))
3240         {
3241         case EOF_CMD:
3242         log_write(L_smtp_connection, LOG_MAIN, "%s closed by EOF",
3243           smtp_get_connection_info());
3244         done = 2;
3245         break;
3246
3247         case QUIT_CMD:
3248         smtp_printf("221 %s closing connection\r\n", smtp_active_hostname);
3249         log_write(L_smtp_connection, LOG_MAIN, "%s closed by QUIT",
3250           smtp_get_connection_info());
3251         done = 2;
3252         break;
3253
3254         default:
3255         smtp_printf("554 Security failure\r\n");
3256         break;
3257         }
3258       }
3259     tls_close(TRUE);
3260     break;
3261     #endif
3262
3263
3264     /* The ACL for QUIT is provided for gathering statistical information or
3265     similar; it does not affect the response code, but it can supply a custom
3266     message. */
3267
3268     case QUIT_CMD:
3269     incomplete_transaction_log(US"QUIT");
3270
3271     if (acl_smtp_quit != NULL)
3272       {
3273       rc = acl_check(ACL_WHERE_QUIT, US"", acl_smtp_quit,&user_msg,&log_msg);
3274       if (rc == ERROR)
3275         log_write(0, LOG_MAIN|LOG_PANIC, "ACL for QUIT returned ERROR: %s",
3276           log_msg);
3277       }
3278     else user_msg = NULL;
3279
3280     if (user_msg == NULL)
3281       smtp_printf("221 %s closing connection\r\n", smtp_active_hostname);
3282     else
3283       smtp_printf("221 %s\r\n", user_msg);
3284
3285     #ifdef SUPPORT_TLS
3286     tls_close(TRUE);
3287     #endif
3288
3289     done = 2;
3290     log_write(L_smtp_connection, LOG_MAIN, "%s closed by QUIT",
3291       smtp_get_connection_info());
3292     break;
3293
3294
3295     case RSET_CMD:
3296     incomplete_transaction_log(US"RSET");
3297     smtp_reset(reset_point);
3298     toomany = FALSE;
3299     smtp_printf("250 Reset OK\r\n");
3300     cmd_list[CMD_LIST_RSET].is_mail_cmd = FALSE;
3301     break;
3302
3303
3304     case NOOP_CMD:
3305     smtp_printf("250 OK\r\n");
3306     break;
3307
3308
3309     /* Show ETRN/EXPN/VRFY if there's
3310     an ACL for checking hosts; if actually used, a check will be done for
3311     permitted hosts. */
3312
3313     case HELP_CMD:
3314     smtp_printf("214-Commands supported:\r\n");
3315       {
3316       uschar buffer[256];
3317       buffer[0] = 0;
3318       Ustrcat(buffer, " AUTH");
3319       #ifdef SUPPORT_TLS
3320       Ustrcat(buffer, " STARTTLS");
3321       #endif
3322       Ustrcat(buffer, " HELO EHLO MAIL RCPT DATA");
3323       Ustrcat(buffer, " NOOP QUIT RSET HELP");
3324       if (acl_smtp_etrn != NULL) Ustrcat(buffer, " ETRN");
3325       if (acl_smtp_expn != NULL) Ustrcat(buffer, " EXPN");
3326       if (acl_smtp_vrfy != NULL) Ustrcat(buffer, " VRFY");
3327       smtp_printf("214%s\r\n", buffer);
3328       }
3329     break;
3330
3331
3332     case EOF_CMD:
3333     incomplete_transaction_log(US"connection lost");
3334     smtp_printf("421 %s lost input connection\r\n", smtp_active_hostname);
3335
3336     /* Don't log by default unless in the middle of a message, as some mailers
3337     just drop the call rather than sending QUIT, and it clutters up the logs.
3338     */
3339
3340     if (sender_address != NULL || recipients_count > 0)
3341       log_write(L_lost_incoming_connection,
3342           LOG_MAIN,
3343           "unexpected %s while reading SMTP command from %s%s",
3344           sender_host_unknown? "EOF" : "disconnection",
3345           host_and_ident(FALSE), smtp_read_error);
3346
3347     else log_write(L_smtp_connection, LOG_MAIN, "%s lost%s",
3348       smtp_get_connection_info(), smtp_read_error);
3349
3350     done = 1;
3351     break;
3352
3353
3354     case ETRN_CMD:
3355     if (sender_address != NULL)
3356       {
3357       done = synprot_error(L_smtp_protocol_error, 503, NULL,
3358         US"ETRN is not permitted inside a transaction");
3359       break;
3360       }
3361
3362     log_write(L_etrn, LOG_MAIN, "ETRN %s received from %s", smtp_data,
3363       host_and_ident(FALSE));
3364
3365     rc = acl_check(ACL_WHERE_ETRN, smtp_data, acl_smtp_etrn, &user_msg,
3366       &log_msg);
3367     if (rc != OK)
3368       {
3369       done = smtp_handle_acl_fail(ACL_WHERE_ETRN, rc, user_msg, log_msg);
3370       break;
3371       }
3372
3373     /* Compute the serialization key for this command. */
3374
3375     etrn_serialize_key = string_sprintf("etrn-%s\n", smtp_data);
3376
3377     /* If a command has been specified for running as a result of ETRN, we
3378     permit any argument to ETRN. If not, only the # standard form is permitted,
3379     since that is strictly the only kind of ETRN that can be implemented
3380     according to the RFC. */
3381
3382     if (smtp_etrn_command != NULL)
3383       {
3384       uschar *error;
3385       BOOL rc;
3386       etrn_command = smtp_etrn_command;
3387       deliver_domain = smtp_data;
3388       rc = transport_set_up_command(&argv, smtp_etrn_command, TRUE, 0, NULL,
3389         US"ETRN processing", &error);
3390       deliver_domain = NULL;
3391       if (!rc)
3392         {
3393         log_write(0, LOG_MAIN|LOG_PANIC, "failed to set up ETRN command: %s",
3394           error);
3395         smtp_printf("458 Internal failure\r\n");
3396         break;
3397         }
3398       }
3399
3400     /* Else set up to call Exim with the -R option. */
3401
3402     else
3403       {
3404       if (*smtp_data++ != '#')
3405         {
3406         done = synprot_error(L_smtp_syntax_error, 501, NULL,
3407           US"argument must begin with #");
3408         break;
3409         }
3410       etrn_command = US"exim -R";
3411       argv = child_exec_exim(CEE_RETURN_ARGV, TRUE, NULL, TRUE, 2, US"-R",
3412         smtp_data);
3413       }
3414
3415     /* If we are host-testing, don't actually do anything. */
3416
3417     if (host_checking)
3418       {
3419       HDEBUG(D_any)
3420         {
3421         debug_printf("ETRN command is: %s\n", etrn_command);
3422         debug_printf("ETRN command execution skipped\n");
3423         }
3424       smtp_printf("250 OK\r\n");
3425       break;
3426       }
3427
3428
3429     /* If ETRN queue runs are to be serialized, check the database to
3430     ensure one isn't already running. */
3431
3432     if (smtp_etrn_serialize && !enq_start(etrn_serialize_key))
3433       {
3434       smtp_printf("458 Already processing %s\r\n", smtp_data);
3435       break;
3436       }
3437
3438     /* Fork a child process and run the command. We don't want to have to
3439     wait for the process at any point, so set SIGCHLD to SIG_IGN before
3440     forking. It should be set that way anyway for external incoming SMTP,
3441     but we save and restore to be tidy. If serialization is required, we
3442     actually run the command in yet another process, so we can wait for it
3443     to complete and then remove the serialization lock. */
3444
3445     oldsignal = signal(SIGCHLD, SIG_IGN);
3446
3447     if ((pid = fork()) == 0)
3448       {
3449       smtp_input = FALSE;    /* This process is not associated with the */
3450       fclose(smtp_in);       /* SMTP call any more. */
3451       fclose(smtp_out);
3452
3453       signal(SIGCHLD, SIG_DFL);      /* Want to catch child */
3454
3455       /* If not serializing, do the exec right away. Otherwise, fork down
3456       into another process. */
3457
3458       if (!smtp_etrn_serialize || (pid = fork()) == 0)
3459         {
3460         DEBUG(D_exec) debug_print_argv(argv);
3461         exim_nullstd();                   /* Ensure std{in,out,err} exist */
3462         execv(CS argv[0], (char *const *)argv);
3463         log_write(0, LOG_MAIN|LOG_PANIC_DIE, "exec of \"%s\" (ETRN) failed: %s",
3464           etrn_command, strerror(errno));
3465         _exit(EXIT_FAILURE);         /* paranoia */
3466         }
3467
3468       /* Obey this if smtp_serialize and the 2nd fork yielded non-zero. That
3469       is, we are in the first subprocess, after forking again. All we can do
3470       for a failing fork is to log it. Otherwise, wait for the 2nd process to
3471       complete, before removing the serialization. */
3472
3473       if (pid < 0)
3474         log_write(0, LOG_MAIN|LOG_PANIC, "2nd fork for serialized ETRN "
3475           "failed: %s", strerror(errno));
3476       else
3477         {
3478         int status;
3479         DEBUG(D_any) debug_printf("waiting for serialized ETRN process %d\n",
3480           (int)pid);
3481         (void)wait(&status);
3482         DEBUG(D_any) debug_printf("serialized ETRN process %d ended\n",
3483           (int)pid);
3484         }
3485
3486       enq_end(etrn_serialize_key);
3487       _exit(EXIT_SUCCESS);
3488       }
3489
3490     /* Back in the top level SMTP process. Check that we started a subprocess
3491     and restore the signal state. */
3492
3493     if (pid < 0)
3494       {
3495       log_write(0, LOG_MAIN|LOG_PANIC, "fork of process for ETRN failed: %s",
3496         strerror(errno));
3497       smtp_printf("458 Unable to fork process\r\n");
3498       if (smtp_etrn_serialize) enq_end(etrn_serialize_key);
3499       }
3500     else smtp_printf("250 OK\r\n");
3501
3502     signal(SIGCHLD, oldsignal);
3503     break;
3504
3505
3506     case BADARG_CMD:
3507     done = synprot_error(L_smtp_syntax_error, 501, NULL,
3508       US"unexpected argument data");
3509     break;
3510
3511
3512     /* This currently happens only for NULLs, but could be extended. */
3513
3514     case BADCHAR_CMD:
3515     done = synprot_error(L_smtp_syntax_error, 0, NULL,       /* Just logs */
3516       US"NULL character(s) present (shown as '?')");
3517     smtp_printf("501 NULL characters are not allowed in SMTP commands\r\n");
3518     break;
3519
3520
3521     case BADSYN_CMD:
3522     if (smtp_inend >= smtp_inbuffer + in_buffer_size)
3523       smtp_inend = smtp_inbuffer + in_buffer_size - 1;
3524     c = smtp_inend - smtp_inptr;
3525     if (c > 150) c = 150;
3526     smtp_inptr[c] = 0;
3527     incomplete_transaction_log(US"sync failure");
3528     log_write(0, LOG_MAIN|LOG_REJECT, "SMTP protocol violation: "
3529       "synchronization error "
3530       "(next input sent too soon: pipelining was%s advertised): "
3531       "rejected \"%s\" %s next input=\"%s\"",
3532       pipelining_advertised? "" : " not",
3533       cmd_buffer, host_and_ident(TRUE),
3534       string_printing(smtp_inptr));
3535     smtp_printf("554 SMTP synchronization error\r\n");
3536     done = 1;   /* Pretend eof - drops connection */
3537     break;
3538
3539
3540     case TOO_MANY_NONMAIL_CMD:
3541     incomplete_transaction_log(US"too many non-mail commands");
3542     log_write(0, LOG_MAIN|LOG_REJECT, "SMTP call from %s dropped: too many "
3543       "nonmail commands (last was \"%.*s\")",  host_and_ident(FALSE),
3544       smtp_data - cmd_buffer, cmd_buffer);
3545     smtp_printf("554 Too many nonmail commands\r\n");
3546     done = 1;   /* Pretend eof - drops connection */
3547     break;
3548
3549
3550     default:
3551     if (unknown_command_count++ >= smtp_max_unknown_commands)
3552       {
3553       log_write(L_smtp_syntax_error, LOG_MAIN,
3554         "SMTP syntax error in \"%s\" %s %s",
3555         string_printing(cmd_buffer), host_and_ident(TRUE),
3556         US"unrecognized command");
3557       incomplete_transaction_log(US"unrecognized command");
3558       smtp_printf("500 Too many unrecognized commands\r\n");
3559       done = 2;
3560       log_write(0, LOG_MAIN|LOG_REJECT, "SMTP call from %s dropped: too many "
3561         "unrecognized commands (last was \"%s\")", host_and_ident(FALSE),
3562         cmd_buffer);
3563       }
3564     else
3565       done = synprot_error(L_smtp_syntax_error, 500, NULL,
3566         US"unrecognized command");
3567     break;
3568     }
3569
3570   /* This label is used by goto's inside loops that want to break out to
3571   the end of the command-processing loop. */
3572
3573   COMMAND_LOOP:
3574   last_was_rej_mail = was_rej_mail;     /* Remember some last commands for */
3575   last_was_rcpt = was_rcpt;             /* protocol error handling */
3576   continue;
3577   }
3578
3579 return done - 2;  /* Convert yield values */
3580 }
3581
3582 /* End of smtp_in.c */