1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
5 /* Copyright (c) University of Cambridge 1995 - 2009 */
6 /* See the file NOTICE for conditions of use and distribution. */
8 /* Functions for handling an incoming SMTP call. */
14 /* Initialize for TCP wrappers if so configured. It appears that the macro
15 HAVE_IPV6 is used in some versions of the tcpd.h header, so we unset it before
16 including that header, and restore its value afterwards. */
18 #ifdef USE_TCP_WRAPPERS
21 #define EXIM_HAVE_IPV6
27 #define HAVE_IPV6 TRUE
30 int allow_severity = LOG_INFO;
31 int deny_severity = LOG_NOTICE;
32 uschar *tcp_wrappers_name;
36 /* Size of buffer for reading SMTP commands. We used to use 512, as defined
37 by RFC 821. However, RFC 1869 specifies that this must be increased for SMTP
38 commands that accept arguments, and this in particular applies to AUTH, where
39 the data can be quite long. More recently this value was 2048 in Exim;
40 however, RFC 4954 (circa 2007) recommends 12288 bytes to handle AUTH. Clients
41 such as Thunderbird will send an AUTH with an initial-response for GSSAPI.
42 The maximum size of a Kerberos ticket under Windows 2003 is 12000 bytes, and
43 we need room to handle large base64-encoded AUTHs for GSSAPI.
46 #define smtp_cmd_buffer_size 16384
48 /* Size of buffer for reading SMTP incoming packets */
50 #define in_buffer_size 8192
52 /* Structure for SMTP command list */
59 short int is_mail_cmd;
62 /* Codes for identifying commands. We order them so that those that come first
63 are those for which synchronization is always required. Checking this can help
67 /* These commands are required to be synchronized, i.e. to be the last in a
68 block of commands when pipelining. */
70 HELO_CMD, EHLO_CMD, DATA_CMD, /* These are listed in the pipelining */
71 VRFY_CMD, EXPN_CMD, NOOP_CMD, /* RFC as requiring synchronization */
72 ETRN_CMD, /* This by analogy with TURN from the RFC */
73 STARTTLS_CMD, /* Required by the STARTTLS RFC */
75 /* This is a dummy to identify the non-sync commands when pipelining */
77 NON_SYNC_CMD_PIPELINING,
79 /* These commands need not be synchronized when pipelining */
81 MAIL_CMD, RCPT_CMD, RSET_CMD,
83 /* This is a dummy to identify the non-sync commands when not pipelining */
85 NON_SYNC_CMD_NON_PIPELINING,
87 /* I have been unable to find a statement about the use of pipelining
88 with AUTH, so to be on the safe side it is here, though I kind of feel
89 it should be up there with the synchronized commands. */
93 /* I'm not sure about these, but I don't think they matter. */
97 /* These are specials that don't correspond to actual commands */
99 EOF_CMD, OTHER_CMD, BADARG_CMD, BADCHAR_CMD, BADSYN_CMD,
100 TOO_MANY_NONMAIL_CMD };
103 /* This is a convenience macro for adding the identity of an SMTP command
104 to the circular buffer that holds a list of the last n received. */
107 smtp_connection_had[smtp_ch_index++] = n; \
108 if (smtp_ch_index >= SMTP_HBUFF_SIZE) smtp_ch_index = 0
111 /*************************************************
112 * Local static variables *
113 *************************************************/
115 static auth_instance *authenticated_by;
116 static BOOL auth_advertised;
118 static BOOL tls_advertised;
121 static BOOL helo_required = FALSE;
122 static BOOL helo_verify = FALSE;
123 static BOOL helo_seen;
124 static BOOL helo_accept_junk;
125 static BOOL count_nonmail;
126 static BOOL pipelining_advertised;
127 static BOOL rcpt_smtp_response_same;
128 static BOOL rcpt_in_progress;
129 static int nonmail_command_count;
130 static BOOL smtp_exit_function_called = 0;
131 static int synprot_error_count;
132 static int unknown_command_count;
133 static int sync_cmd_limit;
134 static int smtp_write_error = 0;
136 static uschar *rcpt_smtp_response;
137 static uschar *smtp_data_buffer;
138 static uschar *smtp_cmd_data;
140 /* We need to know the position of RSET, HELO, EHLO, AUTH, and STARTTLS. Their
141 final fields of all except AUTH are forced TRUE at the start of a new message
142 setup, to allow one of each between messages that is not counted as a nonmail
143 command. (In fact, only one of HELO/EHLO is not counted.) Also, we have to
144 allow a new EHLO after starting up TLS.
146 AUTH is "falsely" labelled as a mail command initially, so that it doesn't get
147 counted. However, the flag is changed when AUTH is received, so that multiple
148 failing AUTHs will eventually hit the limit. After a successful AUTH, another
149 AUTH is already forbidden. After a TLS session is started, AUTH's flag is again
150 forced TRUE, to allow for the re-authentication that can happen at that point.
152 QUIT is also "falsely" labelled as a mail command so that it doesn't up the
153 count of non-mail commands and possibly provoke an error. */
155 static smtp_cmd_list cmd_list[] = {
156 { "rset", sizeof("rset")-1, RSET_CMD, FALSE, FALSE }, /* First */
157 { "helo", sizeof("helo")-1, HELO_CMD, TRUE, FALSE },
158 { "ehlo", sizeof("ehlo")-1, EHLO_CMD, TRUE, FALSE },
159 { "auth", sizeof("auth")-1, AUTH_CMD, TRUE, TRUE },
161 { "starttls", sizeof("starttls")-1, STARTTLS_CMD, FALSE, FALSE },
164 /* If you change anything above here, also fix the definitions below. */
166 { "mail from:", sizeof("mail from:")-1, MAIL_CMD, TRUE, TRUE },
167 { "rcpt to:", sizeof("rcpt to:")-1, RCPT_CMD, TRUE, TRUE },
168 { "data", sizeof("data")-1, DATA_CMD, FALSE, TRUE },
169 { "quit", sizeof("quit")-1, QUIT_CMD, FALSE, TRUE },
170 { "noop", sizeof("noop")-1, NOOP_CMD, TRUE, FALSE },
171 { "etrn", sizeof("etrn")-1, ETRN_CMD, TRUE, FALSE },
172 { "vrfy", sizeof("vrfy")-1, VRFY_CMD, TRUE, FALSE },
173 { "expn", sizeof("expn")-1, EXPN_CMD, TRUE, FALSE },
174 { "help", sizeof("help")-1, HELP_CMD, TRUE, FALSE }
177 static smtp_cmd_list *cmd_list_end =
178 cmd_list + sizeof(cmd_list)/sizeof(smtp_cmd_list);
180 #define CMD_LIST_RSET 0
181 #define CMD_LIST_HELO 1
182 #define CMD_LIST_EHLO 2
183 #define CMD_LIST_AUTH 3
184 #define CMD_LIST_STARTTLS 4
186 /* This list of names is used for performing the smtp_no_mail logging action.
187 It must be kept in step with the SCH_xxx enumerations. */
189 static uschar *smtp_names[] =
191 US"NONE", US"AUTH", US"DATA", US"EHLO", US"ETRN", US"EXPN", US"HELO",
192 US"HELP", US"MAIL", US"NOOP", US"QUIT", US"RCPT", US"RSET", US"STARTTLS",
195 static uschar *protocols[] = {
196 US"local-smtp", /* HELO */
197 US"local-smtps", /* The rare case EHLO->STARTTLS->HELO */
198 US"local-esmtp", /* EHLO */
199 US"local-esmtps", /* EHLO->STARTTLS->EHLO */
200 US"local-esmtpa", /* EHLO->AUTH */
201 US"local-esmtpsa" /* EHLO->STARTTLS->EHLO->AUTH */
206 #define pcrpted 1 /* added to pextend or pnormal */
207 #define pauthed 2 /* added to pextend */
208 #define pnlocal 6 /* offset to remove "local" */
210 /* When reading SMTP from a remote host, we have to use our own versions of the
211 C input-reading functions, in order to be able to flush the SMTP output only
212 when about to read more data from the socket. This is the only way to get
213 optimal performance when the client is using pipelining. Flushing for every
214 command causes a separate packet and reply packet each time; saving all the
215 responses up (when pipelining) combines them into one packet and one response.
217 For simplicity, these functions are used for *all* SMTP input, not only when
218 receiving over a socket. However, after setting up a secure socket (SSL), input
219 is read via the OpenSSL library, and another set of functions is used instead
222 These functions are set in the receive_getc etc. variables and called with the
223 same interface as the C functions. However, since there can only ever be
224 one incoming SMTP call, we just use a single buffer and flags. There is no need
225 to implement a complicated private FILE-like structure.*/
227 static uschar *smtp_inbuffer;
228 static uschar *smtp_inptr;
229 static uschar *smtp_inend;
230 static int smtp_had_eof;
231 static int smtp_had_error;
234 /*************************************************
235 * SMTP version of getc() *
236 *************************************************/
238 /* This gets the next byte from the SMTP input buffer. If the buffer is empty,
239 it flushes the output, and refills the buffer, with a timeout. The signal
240 handler is set appropriately by the calling function. This function is not used
241 after a connection has negotated itself into an TLS/SSL state.
244 Returns: the next character or EOF
250 if (smtp_inptr >= smtp_inend)
254 if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
255 rc = read(fileno(smtp_in), smtp_inbuffer, in_buffer_size);
260 /* Must put the error text in fixed store, because this might be during
261 header reading, where it releases unused store above the header. */
264 smtp_had_error = save_errno;
265 smtp_read_error = string_copy_malloc(
266 string_sprintf(" (error: %s)", strerror(save_errno)));
268 else smtp_had_eof = 1;
272 dkim_exim_verify_feed(smtp_inbuffer, rc);
274 smtp_inend = smtp_inbuffer + rc;
275 smtp_inptr = smtp_inbuffer;
277 return *smtp_inptr++;
282 /*************************************************
283 * SMTP version of ungetc() *
284 *************************************************/
286 /* Puts a character back in the input buffer. Only ever
292 Returns: the character
298 *(--smtp_inptr) = ch;
305 /*************************************************
306 * SMTP version of feof() *
307 *************************************************/
309 /* Tests for a previous EOF
312 Returns: non-zero if the eof flag is set
324 /*************************************************
325 * SMTP version of ferror() *
326 *************************************************/
328 /* Tests for a previous read error, and returns with errno
329 restored to what it was when the error was detected.
332 Returns: non-zero if the error flag is set
338 errno = smtp_had_error;
339 return smtp_had_error;
344 /*************************************************
345 * Test for characters in the SMTP buffer *
346 *************************************************/
348 /* Used at the end of a message
357 return smtp_inptr < smtp_inend;
362 /*************************************************
363 * Write formatted string to SMTP channel *
364 *************************************************/
366 /* This is a separate function so that we don't have to repeat everything for
367 TLS support or debugging. It is global so that the daemon and the
368 authentication functions can use it. It does not return any error indication,
369 because major problems such as dropped connections won't show up till an output
370 flush for non-TLS connections. The smtp_fflush() function is available for
371 checking that: for convenience, TLS output errors are remembered here so that
372 they are also picked up later by smtp_fflush().
376 ... optional arguments
382 smtp_printf(const char *format, ...)
386 va_start(ap, format);
387 smtp_vprintf(format, ap);
391 /* This is split off so that verify.c:respond_printf() can, in effect, call
392 smtp_printf(), bearing in mind that in C a vararg function can't directly
393 call another vararg function, only a function which accepts a va_list. */
396 smtp_vprintf(const char *format, va_list ap)
400 yield = string_vformat(big_buffer, big_buffer_size, format, ap);
404 void *reset_point = store_get(0);
405 uschar *msg_copy, *cr, *end;
406 msg_copy = string_copy(big_buffer);
407 end = msg_copy + Ustrlen(msg_copy);
408 while ((cr = Ustrchr(msg_copy, '\r')) != NULL) /* lose CRs */
409 memmove(cr, cr + 1, (end--) - cr);
410 debug_printf("SMTP>> %s", msg_copy);
411 store_reset(reset_point);
416 log_write(0, LOG_MAIN|LOG_PANIC, "string too large in smtp_printf()");
417 smtp_closedown(US"Unexpected error");
418 exim_exit(EXIT_FAILURE);
421 /* If this is the first output for a (non-batch) RCPT command, see if all RCPTs
422 have had the same. Note: this code is also present in smtp_respond(). It would
423 be tidier to have it only in one place, but when it was added, it was easier to
424 do it that way, so as not to have to mess with the code for the RCPT command,
425 which sometimes uses smtp_printf() and sometimes smtp_respond(). */
427 if (rcpt_in_progress)
429 if (rcpt_smtp_response == NULL)
430 rcpt_smtp_response = string_copy(big_buffer);
431 else if (rcpt_smtp_response_same &&
432 Ustrcmp(rcpt_smtp_response, big_buffer) != 0)
433 rcpt_smtp_response_same = FALSE;
434 rcpt_in_progress = FALSE;
437 /* Now write the string */
442 if (tls_write(big_buffer, Ustrlen(big_buffer)) < 0) smtp_write_error = -1;
447 if (fprintf(smtp_out, "%s", big_buffer) < 0) smtp_write_error = -1;
452 /*************************************************
453 * Flush SMTP out and check for error *
454 *************************************************/
456 /* This function isn't currently used within Exim (it detects errors when it
457 tries to read the next SMTP input), but is available for use in local_scan().
458 For non-TLS connections, it flushes the output and checks for errors. For
459 TLS-connections, it checks for a previously-detected TLS write error.
462 Returns: 0 for no error; -1 after an error
468 if (tls_active < 0 && fflush(smtp_out) != 0) smtp_write_error = -1;
469 return smtp_write_error;
474 /*************************************************
475 * SMTP command read timeout *
476 *************************************************/
478 /* Signal handler for timing out incoming SMTP commands. This attempts to
481 Argument: signal number (SIGALRM)
486 command_timeout_handler(int sig)
488 sig = sig; /* Keep picky compilers happy */
489 log_write(L_lost_incoming_connection,
490 LOG_MAIN, "SMTP command timeout on%s connection from %s",
491 (tls_active >= 0)? " TLS" : "",
492 host_and_ident(FALSE));
493 if (smtp_batched_input)
494 moan_smtp_batch(NULL, "421 SMTP command timeout"); /* Does not return */
495 smtp_notquit_exit(US"command-timeout", US"421",
496 US"%s: SMTP command timeout - closing connection", smtp_active_hostname);
497 exim_exit(EXIT_FAILURE);
502 /*************************************************
504 *************************************************/
506 /* Signal handler for handling SIGTERM. Again, try to finish tidily.
508 Argument: signal number (SIGTERM)
513 command_sigterm_handler(int sig)
515 sig = sig; /* Keep picky compilers happy */
516 log_write(0, LOG_MAIN, "%s closed after SIGTERM", smtp_get_connection_info());
517 if (smtp_batched_input)
518 moan_smtp_batch(NULL, "421 SIGTERM received"); /* Does not return */
519 smtp_notquit_exit(US"signal-exit", US"421",
520 US"%s: Service not available - closing connection", smtp_active_hostname);
521 exim_exit(EXIT_FAILURE);
527 /*************************************************
528 * Read one command line *
529 *************************************************/
531 /* Strictly, SMTP commands coming over the net are supposed to end with CRLF.
532 There are sites that don't do this, and in any case internal SMTP probably
533 should check only for LF. Consequently, we check here for LF only. The line
534 ends up with [CR]LF removed from its end. If we get an overlong line, treat as
535 an unknown command. The command is read into the global smtp_cmd_buffer so that
536 it is available via $smtp_command.
538 The character reading routine sets up a timeout for each block actually read
539 from the input (which may contain more than one command). We set up a special
540 signal handler that closes down the session on a timeout. Control does not
544 check_sync if TRUE, check synchronization rules if global option is TRUE
546 Returns: a code identifying the command (enumerated above)
550 smtp_read_command(BOOL check_sync)
555 BOOL hadnull = FALSE;
557 os_non_restarting_signal(SIGALRM, command_timeout_handler);
559 while ((c = (receive_getc)()) != '\n' && c != EOF)
561 if (ptr >= smtp_cmd_buffer_size)
563 os_non_restarting_signal(SIGALRM, sigalrm_handler);
571 smtp_cmd_buffer[ptr++] = c;
574 receive_linecount++; /* For BSMTP errors */
575 os_non_restarting_signal(SIGALRM, sigalrm_handler);
577 /* If hit end of file, return pseudo EOF command. Whether we have a
578 part-line already read doesn't matter, since this is an error state. */
580 if (c == EOF) return EOF_CMD;
582 /* Remove any CR and white space at the end of the line, and terminate the
585 while (ptr > 0 && isspace(smtp_cmd_buffer[ptr-1])) ptr--;
586 smtp_cmd_buffer[ptr] = 0;
588 DEBUG(D_receive) debug_printf("SMTP<< %s\n", smtp_cmd_buffer);
590 /* NULLs are not allowed in SMTP commands */
592 if (hadnull) return BADCHAR_CMD;
594 /* Scan command list and return identity, having set the data pointer
595 to the start of the actual data characters. Check for SMTP synchronization
598 for (p = cmd_list; p < cmd_list_end; p++)
600 if (strncmpic(smtp_cmd_buffer, US p->name, p->len) == 0 &&
601 (smtp_cmd_buffer[p->len-1] == ':' || /* "mail from:" or "rcpt to:" */
602 smtp_cmd_buffer[p->len] == 0 ||
603 smtp_cmd_buffer[p->len] == ' '))
605 if (smtp_inptr < smtp_inend && /* Outstanding input */
606 p->cmd < sync_cmd_limit && /* Command should sync */
607 check_sync && /* Local flag set */
608 smtp_enforce_sync && /* Global flag set */
609 sender_host_address != NULL && /* Not local input */
610 !sender_host_notsocket) /* Really is a socket */
613 /* The variables $smtp_command and $smtp_command_argument point into the
614 unmodified input buffer. A copy of the latter is taken for actual
615 processing, so that it can be chopped up into separate parts if necessary,
616 for example, when processing a MAIL command options such as SIZE that can
617 follow the sender address. */
619 smtp_cmd_argument = smtp_cmd_buffer + p->len;
620 while (isspace(*smtp_cmd_argument)) smtp_cmd_argument++;
621 Ustrcpy(smtp_data_buffer, smtp_cmd_argument);
622 smtp_cmd_data = smtp_data_buffer;
624 /* Count non-mail commands from those hosts that are controlled in this
625 way. The default is all hosts. We don't waste effort checking the list
626 until we get a non-mail command, but then cache the result to save checking
627 again. If there's a DEFER while checking the host, assume it's in the list.
629 Note that one instance of RSET, EHLO/HELO, and STARTTLS is allowed at the
630 start of each incoming message by fiddling with the value in the table. */
634 if (count_nonmail == TRUE_UNSET) count_nonmail =
635 verify_check_host(&smtp_accept_max_nonmail_hosts) != FAIL;
636 if (count_nonmail && ++nonmail_command_count > smtp_accept_max_nonmail)
637 return TOO_MANY_NONMAIL_CMD;
640 /* If there is data for a command that does not expect it, generate the
643 return (p->has_arg || *smtp_cmd_data == 0)? p->cmd : BADARG_CMD;
647 /* Enforce synchronization for unknown commands */
649 if (smtp_inptr < smtp_inend && /* Outstanding input */
650 check_sync && /* Local flag set */
651 smtp_enforce_sync && /* Global flag set */
652 sender_host_address != NULL && /* Not local input */
653 !sender_host_notsocket) /* Really is a socket */
661 /*************************************************
662 * Recheck synchronization *
663 *************************************************/
665 /* Synchronization checks can never be perfect because a packet may be on its
666 way but not arrived when the check is done. Such checks can in any case only be
667 done when TLS is not in use. Normally, the checks happen when commands are
668 read: Exim ensures that there is no more input in the input buffer. In normal
669 cases, the response to the command will be fast, and there is no further check.
671 However, for some commands an ACL is run, and that can include delays. In those
672 cases, it is useful to do another check on the input just before sending the
673 response. This also applies at the start of a connection. This function does
674 that check by means of the select() function, as long as the facility is not
675 disabled or inappropriate. A failure of select() is ignored.
677 When there is unwanted input, we read it so that it appears in the log of the
681 Returns: TRUE if all is well; FALSE if there is input pending
689 struct timeval tzero;
691 if (!smtp_enforce_sync || sender_host_address == NULL ||
692 sender_host_notsocket || tls_active >= 0)
695 fd = fileno(smtp_in);
700 rc = select(fd + 1, (SELECT_ARG2_TYPE *)&fds, NULL, NULL, &tzero);
702 if (rc <= 0) return TRUE; /* Not ready to read */
704 if (rc < 0) return TRUE; /* End of file or error */
707 rc = smtp_inend - smtp_inptr;
708 if (rc > 150) rc = 150;
715 /*************************************************
716 * Forced closedown of call *
717 *************************************************/
719 /* This function is called from log.c when Exim is dying because of a serious
720 disaster, and also from some other places. If an incoming non-batched SMTP
721 channel is open, it swallows the rest of the incoming message if in the DATA
722 phase, sends the reply string, and gives an error to all subsequent commands
723 except QUIT. The existence of an SMTP call is detected by the non-NULLness of
727 message SMTP reply string to send, excluding the code
733 smtp_closedown(uschar *message)
735 if (smtp_in == NULL || smtp_batched_input) return;
736 receive_swallow_smtp();
737 smtp_printf("421 %s\r\n", message);
741 switch(smtp_read_command(FALSE))
747 smtp_printf("221 %s closing connection\r\n", smtp_active_hostname);
752 smtp_printf("250 Reset OK\r\n");
756 smtp_printf("421 %s\r\n", message);
765 /*************************************************
766 * Set up connection info for logging *
767 *************************************************/
769 /* This function is called when logging information about an SMTP connection.
770 It sets up appropriate source information, depending on the type of connection.
771 If sender_fullhost is NULL, we are at a very early stage of the connection;
772 just use the IP address.
775 Returns: a string describing the connection
779 smtp_get_connection_info(void)
781 uschar *hostname = (sender_fullhost == NULL)?
782 sender_host_address : sender_fullhost;
785 return string_sprintf("SMTP connection from %s", hostname);
787 if (sender_host_unknown || sender_host_notsocket)
788 return string_sprintf("SMTP connection from %s", sender_ident);
791 return string_sprintf("SMTP connection from %s (via inetd)", hostname);
793 if ((log_extra_selector & LX_incoming_interface) != 0 &&
794 interface_address != NULL)
795 return string_sprintf("SMTP connection from %s I=[%s]:%d", hostname,
796 interface_address, interface_port);
798 return string_sprintf("SMTP connection from %s", hostname);
803 /*************************************************
804 * Log lack of MAIL if so configured *
805 *************************************************/
807 /* This function is called when an SMTP session ends. If the log selector
808 smtp_no_mail is set, write a log line giving some details of what has happened
816 smtp_log_no_mail(void)
821 if (smtp_mailcmd_count > 0 || (log_extra_selector & LX_smtp_no_mail) == 0)
827 if (sender_host_authenticated != NULL)
829 s = string_append(s, &size, &ptr, 2, US" A=", sender_host_authenticated);
830 if (authenticated_id != NULL)
831 s = string_append(s, &size, &ptr, 2, US":", authenticated_id);
835 if ((log_extra_selector & LX_tls_cipher) != 0 && tls_cipher != NULL)
836 s = string_append(s, &size, &ptr, 2, US" X=", tls_cipher);
837 if ((log_extra_selector & LX_tls_certificate_verified) != 0 &&
839 s = string_append(s, &size, &ptr, 2, US" CV=",
840 tls_certificate_verified? "yes":"no");
841 if ((log_extra_selector & LX_tls_peerdn) != 0 && tls_peerdn != NULL)
842 s = string_append(s, &size, &ptr, 3, US" DN=\"",
843 string_printing(tls_peerdn), US"\"");
846 sep = (smtp_connection_had[SMTP_HBUFF_SIZE-1] != SCH_NONE)?
847 US" C=..." : US" C=";
848 for (i = smtp_ch_index; i < SMTP_HBUFF_SIZE; i++)
850 if (smtp_connection_had[i] != SCH_NONE)
852 s = string_append(s, &size, &ptr, 2, sep,
853 smtp_names[smtp_connection_had[i]]);
858 for (i = 0; i < smtp_ch_index; i++)
860 s = string_append(s, &size, &ptr, 2, sep, smtp_names[smtp_connection_had[i]]);
864 if (s != NULL) s[ptr] = 0; else s = US"";
865 log_write(0, LOG_MAIN, "no MAIL in SMTP connection from %s D=%s%s",
866 host_and_ident(FALSE),
867 readconf_printtime(time(NULL) - smtp_connection_start), s);
872 /*************************************************
873 * Check HELO line and set sender_helo_name *
874 *************************************************/
876 /* Check the format of a HELO line. The data for HELO/EHLO is supposed to be
877 the domain name of the sending host, or an ip literal in square brackets. The
878 arrgument is placed in sender_helo_name, which is in malloc store, because it
879 must persist over multiple incoming messages. If helo_accept_junk is set, this
880 host is permitted to send any old junk (needed for some broken hosts).
881 Otherwise, helo_allow_chars can be used for rogue characters in general
882 (typically people want to let in underscores).
885 s the data portion of the line (already past any white space)
887 Returns: TRUE or FALSE
891 check_helo(uschar *s)
894 uschar *end = s + Ustrlen(s);
895 BOOL yield = helo_accept_junk;
897 /* Discard any previous helo name */
899 if (sender_helo_name != NULL)
901 store_free(sender_helo_name);
902 sender_helo_name = NULL;
905 /* Skip tests if junk is permitted. */
909 /* Allow the new standard form for IPv6 address literals, namely,
910 [IPv6:....], and because someone is bound to use it, allow an equivalent
911 IPv4 form. Allow plain addresses as well. */
918 if (strncmpic(s, US"[IPv6:", 6) == 0)
919 yield = (string_is_ip_address(s+6, NULL) == 6);
920 else if (strncmpic(s, US"[IPv4:", 6) == 0)
921 yield = (string_is_ip_address(s+6, NULL) == 4);
923 yield = (string_is_ip_address(s+1, NULL) != 0);
928 /* Non-literals must be alpha, dot, hyphen, plus any non-valid chars
929 that have been configured (usually underscore - sigh). */
936 if (!isalnum(*s) && *s != '.' && *s != '-' &&
937 Ustrchr(helo_allow_chars, *s) == NULL)
947 /* Save argument if OK */
949 if (yield) sender_helo_name = string_copy_malloc(start);
957 /*************************************************
958 * Extract SMTP command option *
959 *************************************************/
961 /* This function picks the next option setting off the end of smtp_cmd_data. It
962 is called for MAIL FROM and RCPT TO commands, to pick off the optional ESMTP
963 things that can appear there.
966 name point this at the name
967 value point this at the data string
969 Returns: TRUE if found an option
973 extract_option(uschar **name, uschar **value)
976 uschar *v = smtp_cmd_data + Ustrlen(smtp_cmd_data) - 1;
977 while (isspace(*v)) v--;
980 while (v > smtp_cmd_data && *v != '=' && !isspace(*v)) v--;
981 if (*v != '=') return FALSE;
984 while(isalpha(n[-1])) n--;
986 /* RFC says SP, but TAB seen in wild and other major MTAs accept it */
987 if (!isspace(n[-1])) return FALSE;
1000 /*************************************************
1001 * Reset for new message *
1002 *************************************************/
1004 /* This function is called whenever the SMTP session is reset from
1005 within either of the setup functions.
1007 Argument: the stacking pool storage reset point
1012 smtp_reset(void *reset_point)
1014 store_reset(reset_point);
1015 recipients_list = NULL;
1016 rcpt_count = rcpt_defer_count = rcpt_fail_count =
1017 raw_recipients_count = recipients_count = recipients_list_max = 0;
1018 message_linecount = 0;
1020 acl_added_headers = NULL;
1021 queue_only_policy = FALSE;
1022 rcpt_smtp_response = NULL;
1023 rcpt_smtp_response_same = TRUE;
1024 rcpt_in_progress = FALSE;
1025 deliver_freeze = FALSE; /* Can be set by ACL */
1026 freeze_tell = freeze_tell_config; /* Can be set by ACL */
1027 fake_response = OK; /* Can be set by ACL */
1028 #ifdef WITH_CONTENT_SCAN
1029 no_mbox_unspool = FALSE; /* Can be set by ACL */
1031 submission_mode = FALSE; /* Can be set by ACL */
1032 suppress_local_fixups = FALSE; /* Can be set by ACL */
1033 active_local_from_check = local_from_check; /* Can be set by ACL */
1034 active_local_sender_retain = local_sender_retain; /* Can be set by ACL */
1035 sender_address = NULL;
1036 submission_name = NULL; /* Can be set by ACL */
1037 raw_sender = NULL; /* After SMTP rewrite, before qualifying */
1038 sender_address_unrewritten = NULL; /* Set only after verify rewrite */
1039 sender_verified_list = NULL; /* No senders verified */
1040 memset(sender_address_cache, 0, sizeof(sender_address_cache));
1041 memset(sender_domain_cache, 0, sizeof(sender_domain_cache));
1042 authenticated_sender = NULL;
1043 #ifdef EXPERIMENTAL_BRIGHTMAIL
1045 bmi_verdicts = NULL;
1047 #ifndef DISABLE_DKIM
1048 dkim_signers = NULL;
1049 dkim_disable_verify = FALSE;
1050 dkim_collect_input = FALSE;
1052 #ifdef EXPERIMENTAL_SPF
1053 spf_header_comment = NULL;
1054 spf_received = NULL;
1056 spf_smtp_comment = NULL;
1058 body_linecount = body_zerocount = 0;
1060 sender_rate = sender_rate_limit = sender_rate_period = NULL;
1061 ratelimiters_mail = NULL; /* Updated by ratelimit ACL condition */
1062 /* Note that ratelimiters_conn persists across resets. */
1064 /* Reset message ACL variables */
1068 /* The message body variables use malloc store. They may be set if this is
1069 not the first message in an SMTP session and the previous message caused them
1070 to be referenced in an ACL. */
1072 if (message_body != NULL)
1074 store_free(message_body);
1075 message_body = NULL;
1078 if (message_body_end != NULL)
1080 store_free(message_body_end);
1081 message_body_end = NULL;
1084 /* Warning log messages are also saved in malloc store. They are saved to avoid
1085 repetition in the same message, but it seems right to repeat them for different
1088 while (acl_warn_logged != NULL)
1090 string_item *this = acl_warn_logged;
1091 acl_warn_logged = acl_warn_logged->next;
1100 /*************************************************
1101 * Initialize for incoming batched SMTP message *
1102 *************************************************/
1104 /* This function is called from smtp_setup_msg() in the case when
1105 smtp_batched_input is true. This happens when -bS is used to pass a whole batch
1106 of messages in one file with SMTP commands between them. All errors must be
1107 reported by sending a message, and only MAIL FROM, RCPT TO, and DATA are
1108 relevant. After an error on a sender, or an invalid recipient, the remainder
1109 of the message is skipped. The value of received_protocol is already set.
1112 Returns: > 0 message successfully started (reached DATA)
1113 = 0 QUIT read or end of file reached
1114 < 0 should not occur
1118 smtp_setup_batch_msg(void)
1121 void *reset_point = store_get(0);
1123 /* Save the line count at the start of each transaction - single commands
1124 like HELO and RSET count as whole transactions. */
1126 bsmtp_transaction_linecount = receive_linecount;
1128 if ((receive_feof)()) return 0; /* Treat EOF as QUIT */
1130 smtp_reset(reset_point); /* Reset for start of message */
1132 /* Deal with SMTP commands. This loop is exited by setting done to a POSITIVE
1133 value. The values are 2 larger than the required yield of the function. */
1138 uschar *recipient = NULL;
1139 int start, end, sender_domain, recipient_domain;
1141 switch(smtp_read_command(FALSE))
1143 /* The HELO/EHLO commands set sender_address_helo if they have
1144 valid data; otherwise they are ignored, except that they do
1145 a reset of the state. */
1150 check_helo(smtp_cmd_data);
1154 smtp_reset(reset_point);
1155 bsmtp_transaction_linecount = receive_linecount;
1159 /* The MAIL FROM command requires an address as an operand. All we
1160 do here is to parse it for syntactic correctness. The form "<>" is
1161 a special case which converts into an empty string. The start/end
1162 pointers in the original are not used further for this address, as
1163 it is the canonical extracted address which is all that is kept. */
1166 if (sender_address != NULL)
1167 /* The function moan_smtp_batch() does not return. */
1168 moan_smtp_batch(smtp_cmd_buffer, "503 Sender already given");
1170 if (smtp_cmd_data[0] == 0)
1171 /* The function moan_smtp_batch() does not return. */
1172 moan_smtp_batch(smtp_cmd_buffer, "501 MAIL FROM must have an address operand");
1174 /* Reset to start of message */
1176 smtp_reset(reset_point);
1178 /* Apply SMTP rewrite */
1180 raw_sender = ((rewrite_existflags & rewrite_smtp) != 0)?
1181 rewrite_one(smtp_cmd_data, rewrite_smtp|rewrite_smtp_sender, NULL, FALSE,
1182 US"", global_rewrite_rules) : smtp_cmd_data;
1184 /* Extract the address; the TRUE flag allows <> as valid */
1187 parse_extract_address(raw_sender, &errmess, &start, &end, &sender_domain,
1190 if (raw_sender == NULL)
1191 /* The function moan_smtp_batch() does not return. */
1192 moan_smtp_batch(smtp_cmd_buffer, "501 %s", errmess);
1194 sender_address = string_copy(raw_sender);
1196 /* Qualify unqualified sender addresses if permitted to do so. */
1198 if (sender_domain == 0 && sender_address[0] != 0 && sender_address[0] != '@')
1200 if (allow_unqualified_sender)
1202 sender_address = rewrite_address_qualify(sender_address, FALSE);
1203 DEBUG(D_receive) debug_printf("unqualified address %s accepted "
1204 "and rewritten\n", raw_sender);
1206 /* The function moan_smtp_batch() does not return. */
1207 else moan_smtp_batch(smtp_cmd_buffer, "501 sender address must contain "
1213 /* The RCPT TO command requires an address as an operand. All we do
1214 here is to parse it for syntactic correctness. There may be any number
1215 of RCPT TO commands, specifying multiple senders. We build them all into
1216 a data structure that is in argc/argv format. The start/end values
1217 given by parse_extract_address are not used, as we keep only the
1218 extracted address. */
1221 if (sender_address == NULL)
1222 /* The function moan_smtp_batch() does not return. */
1223 moan_smtp_batch(smtp_cmd_buffer, "503 No sender yet given");
1225 if (smtp_cmd_data[0] == 0)
1226 /* The function moan_smtp_batch() does not return. */
1227 moan_smtp_batch(smtp_cmd_buffer, "501 RCPT TO must have an address operand");
1229 /* Check maximum number allowed */
1231 if (recipients_max > 0 && recipients_count + 1 > recipients_max)
1232 /* The function moan_smtp_batch() does not return. */
1233 moan_smtp_batch(smtp_cmd_buffer, "%s too many recipients",
1234 recipients_max_reject? "552": "452");
1236 /* Apply SMTP rewrite, then extract address. Don't allow "<>" as a
1237 recipient address */
1239 recipient = ((rewrite_existflags & rewrite_smtp) != 0)?
1240 rewrite_one(smtp_cmd_data, rewrite_smtp, NULL, FALSE, US"",
1241 global_rewrite_rules) : smtp_cmd_data;
1243 /* rfc821_domains = TRUE; << no longer needed */
1244 recipient = parse_extract_address(recipient, &errmess, &start, &end,
1245 &recipient_domain, FALSE);
1246 /* rfc821_domains = FALSE; << no longer needed */
1248 if (recipient == NULL)
1249 /* The function moan_smtp_batch() does not return. */
1250 moan_smtp_batch(smtp_cmd_buffer, "501 %s", errmess);
1252 /* If the recipient address is unqualified, qualify it if permitted. Then
1253 add it to the list of recipients. */
1255 if (recipient_domain == 0)
1257 if (allow_unqualified_recipient)
1259 DEBUG(D_receive) debug_printf("unqualified address %s accepted\n",
1261 recipient = rewrite_address_qualify(recipient, TRUE);
1263 /* The function moan_smtp_batch() does not return. */
1264 else moan_smtp_batch(smtp_cmd_buffer, "501 recipient address must contain "
1267 receive_add_recipient(recipient, -1);
1271 /* The DATA command is legal only if it follows successful MAIL FROM
1272 and RCPT TO commands. This function is complete when a valid DATA
1273 command is encountered. */
1276 if (sender_address == NULL || recipients_count <= 0)
1278 /* The function moan_smtp_batch() does not return. */
1279 if (sender_address == NULL)
1280 moan_smtp_batch(smtp_cmd_buffer,
1281 "503 MAIL FROM:<sender> command must precede DATA");
1283 moan_smtp_batch(smtp_cmd_buffer,
1284 "503 RCPT TO:<recipient> must precede DATA");
1288 done = 3; /* DATA successfully achieved */
1289 message_ended = END_NOTENDED; /* Indicate in middle of message */
1294 /* The VRFY, EXPN, HELP, ETRN, and NOOP commands are ignored. */
1301 bsmtp_transaction_linecount = receive_linecount;
1312 /* The function moan_smtp_batch() does not return. */
1313 moan_smtp_batch(smtp_cmd_buffer, "501 Unexpected argument data");
1318 /* The function moan_smtp_batch() does not return. */
1319 moan_smtp_batch(smtp_cmd_buffer, "501 Unexpected NULL in SMTP command");
1324 /* The function moan_smtp_batch() does not return. */
1325 moan_smtp_batch(smtp_cmd_buffer, "500 Command unrecognized");
1330 return done - 2; /* Convert yield values */
1336 /*************************************************
1337 * Start an SMTP session *
1338 *************************************************/
1340 /* This function is called at the start of an SMTP session. Thereafter,
1341 smtp_setup_msg() is called to initiate each separate message. This
1342 function does host-specific testing, and outputs the banner line.
1345 Returns: FALSE if the session can not continue; something has
1346 gone wrong, or the connection to the host is blocked
1350 smtp_start_session(void)
1354 uschar *user_msg, *log_msg;
1358 smtp_connection_start = time(NULL);
1359 for (smtp_ch_index = 0; smtp_ch_index < SMTP_HBUFF_SIZE; smtp_ch_index++)
1360 smtp_connection_had[smtp_ch_index] = SCH_NONE;
1363 /* Default values for certain variables */
1365 helo_seen = esmtp = helo_accept_junk = FALSE;
1366 smtp_mailcmd_count = 0;
1367 count_nonmail = TRUE_UNSET;
1368 synprot_error_count = unknown_command_count = nonmail_command_count = 0;
1369 smtp_delay_mail = smtp_rlm_base;
1370 auth_advertised = FALSE;
1371 pipelining_advertised = FALSE;
1372 pipelining_enable = TRUE;
1373 sync_cmd_limit = NON_SYNC_CMD_NON_PIPELINING;
1374 smtp_exit_function_called = FALSE; /* For avoiding loop in not-quit exit */
1376 memset(sender_host_cache, 0, sizeof(sender_host_cache));
1378 /* If receiving by -bs from a trusted user, or testing with -bh, we allow
1379 authentication settings from -oMaa to remain in force. */
1381 if (!host_checking && !sender_host_notsocket) sender_host_authenticated = NULL;
1382 authenticated_by = NULL;
1385 tls_cipher = tls_peerdn = NULL;
1386 tls_advertised = FALSE;
1389 /* Reset ACL connection variables */
1393 /* Allow for trailing 0 in the command and data buffers. */
1395 smtp_cmd_buffer = (uschar *)malloc(2*smtp_cmd_buffer_size + 2);
1396 if (smtp_cmd_buffer == NULL)
1397 log_write(0, LOG_MAIN|LOG_PANIC_DIE,
1398 "malloc() failed for SMTP command buffer");
1399 smtp_data_buffer = smtp_cmd_buffer + smtp_cmd_buffer_size + 1;
1401 /* For batched input, the protocol setting can be overridden from the
1402 command line by a trusted caller. */
1404 if (smtp_batched_input)
1406 if (received_protocol == NULL) received_protocol = US"local-bsmtp";
1409 /* For non-batched SMTP input, the protocol setting is forced here. It will be
1410 reset later if any of EHLO/AUTH/STARTTLS are received. */
1414 protocols[pnormal] + ((sender_host_address != NULL)? pnlocal : 0);
1416 /* Set up the buffer for inputting using direct read() calls, and arrange to
1417 call the local functions instead of the standard C ones. */
1419 smtp_inbuffer = (uschar *)malloc(in_buffer_size);
1420 if (smtp_inbuffer == NULL)
1421 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "malloc() failed for SMTP input buffer");
1422 receive_getc = smtp_getc;
1423 receive_ungetc = smtp_ungetc;
1424 receive_feof = smtp_feof;
1425 receive_ferror = smtp_ferror;
1426 receive_smtp_buffered = smtp_buffered;
1427 smtp_inptr = smtp_inend = smtp_inbuffer;
1428 smtp_had_eof = smtp_had_error = 0;
1430 /* Set up the message size limit; this may be host-specific */
1432 thismessage_size_limit = expand_string_integer(message_size_limit, TRUE);
1433 if (expand_string_message != NULL)
1435 if (thismessage_size_limit == -1)
1436 log_write(0, LOG_MAIN|LOG_PANIC, "unable to expand message_size_limit: "
1437 "%s", expand_string_message);
1439 log_write(0, LOG_MAIN|LOG_PANIC, "invalid message_size_limit: "
1440 "%s", expand_string_message);
1441 smtp_closedown(US"Temporary local problem - please try later");
1445 /* When a message is input locally via the -bs or -bS options, sender_host_
1446 unknown is set unless -oMa was used to force an IP address, in which case it
1447 is checked like a real remote connection. When -bs is used from inetd, this
1448 flag is not set, causing the sending host to be checked. The code that deals
1449 with IP source routing (if configured) is never required for -bs or -bS and
1450 the flag sender_host_notsocket is used to suppress it.
1452 If smtp_accept_max and smtp_accept_reserve are set, keep some connections in
1453 reserve for certain hosts and/or networks. */
1455 if (!sender_host_unknown)
1458 BOOL reserved_host = FALSE;
1460 /* Look up IP options (source routing info) on the socket if this is not an
1461 -oMa "host", and if any are found, log them and drop the connection.
1463 Linux (and others now, see below) is different to everyone else, so there
1464 has to be some conditional compilation here. Versions of Linux before 2.1.15
1465 used a structure whose name was "options". Somebody finally realized that
1466 this name was silly, and it got changed to "ip_options". I use the
1467 newer name here, but there is a fudge in the script that sets up os.h
1468 to define a macro in older Linux systems.
1470 Sigh. Linux is a fast-moving target. Another generation of Linux uses
1471 glibc 2, which has chosen ip_opts for the structure name. This is now
1472 really a glibc thing rather than a Linux thing, so the condition name
1473 has been changed to reflect this. It is relevant also to GNU/Hurd.
1475 Mac OS 10.x (Darwin) is like the later glibc versions, but without the
1476 setting of the __GLIBC__ macro, so we can't detect it automatically. There's
1477 a special macro defined in the os.h file.
1479 Some DGUX versions on older hardware appear not to support IP options at
1480 all, so there is now a general macro which can be set to cut out this
1483 How to do this properly in IPv6 is not yet known. */
1485 #if !HAVE_IPV6 && !defined(NO_IP_OPTIONS)
1487 #ifdef GLIBC_IP_OPTIONS
1488 #if (!defined __GLIBC__) || (__GLIBC__ < 2)
1493 #elif defined DARWIN_IP_OPTIONS
1499 if (!host_checking && !sender_host_notsocket)
1502 EXIM_SOCKLEN_T optlen = sizeof(struct ip_options) + MAX_IPOPTLEN;
1503 struct ip_options *ipopt = store_get(optlen);
1505 struct ip_opts ipoptblock;
1506 struct ip_opts *ipopt = &ipoptblock;
1507 EXIM_SOCKLEN_T optlen = sizeof(ipoptblock);
1509 struct ipoption ipoptblock;
1510 struct ipoption *ipopt = &ipoptblock;
1511 EXIM_SOCKLEN_T optlen = sizeof(ipoptblock);
1514 /* Occasional genuine failures of getsockopt() have been seen - for
1515 example, "reset by peer". Therefore, just log and give up on this
1516 call, unless the error is ENOPROTOOPT. This error is given by systems
1517 that have the interfaces but not the mechanism - e.g. GNU/Hurd at the time
1518 of writing. So for that error, carry on - we just can't do an IP options
1521 DEBUG(D_receive) debug_printf("checking for IP options\n");
1523 if (getsockopt(fileno(smtp_out), IPPROTO_IP, IP_OPTIONS, (uschar *)(ipopt),
1526 if (errno != ENOPROTOOPT)
1528 log_write(0, LOG_MAIN, "getsockopt() failed from %s: %s",
1529 host_and_ident(FALSE), strerror(errno));
1530 smtp_printf("451 SMTP service not available\r\n");
1535 /* Deal with any IP options that are set. On the systems I have looked at,
1536 the value of MAX_IPOPTLEN has been 40, meaning that there should never be
1537 more logging data than will fit in big_buffer. Nevertheless, after somebody
1538 questioned this code, I've added in some paranoid checking. */
1540 else if (optlen > 0)
1542 uschar *p = big_buffer;
1543 uschar *pend = big_buffer + big_buffer_size;
1544 uschar *opt, *adptr;
1546 struct in_addr addr;
1549 uschar *optstart = (uschar *)(ipopt->__data);
1551 uschar *optstart = (uschar *)(ipopt->ip_opts);
1553 uschar *optstart = (uschar *)(ipopt->ipopt_list);
1556 DEBUG(D_receive) debug_printf("IP options exist\n");
1558 Ustrcpy(p, "IP options on incoming call:");
1561 for (opt = optstart; opt != NULL &&
1562 opt < (uschar *)(ipopt) + optlen;)
1576 if (!string_format(p, pend-p, " %s [@%s",
1577 (*opt == IPOPT_SSRR)? "SSRR" : "LSRR",
1579 inet_ntoa(*((struct in_addr *)(&(ipopt->faddr))))))
1581 inet_ntoa(ipopt->ip_dst)))
1583 inet_ntoa(ipopt->ipopt_dst)))
1591 optcount = (opt[1] - 3) / sizeof(struct in_addr);
1593 while (optcount-- > 0)
1595 memcpy(&addr, adptr, sizeof(addr));
1596 if (!string_format(p, pend - p - 1, "%s%s",
1597 (optcount == 0)? ":" : "@", inet_ntoa(addr)))
1603 adptr += sizeof(struct in_addr);
1612 if (pend - p < 4 + 3*opt[1]) { opt = NULL; break; }
1615 for (i = 0; i < opt[1]; i++)
1617 sprintf(CS p, "%2.2x ", opt[i]);
1628 log_write(0, LOG_MAIN, "%s", big_buffer);
1630 /* Refuse any call with IP options. This is what tcpwrappers 7.5 does. */
1632 log_write(0, LOG_MAIN|LOG_REJECT,
1633 "connection from %s refused (IP options)", host_and_ident(FALSE));
1635 smtp_printf("554 SMTP service not available\r\n");
1639 /* Length of options = 0 => there are no options */
1641 else DEBUG(D_receive) debug_printf("no IP options found\n");
1643 #endif /* HAVE_IPV6 && !defined(NO_IP_OPTIONS) */
1645 /* Set keep-alive in socket options. The option is on by default. This
1646 setting is an attempt to get rid of some hanging connections that stick in
1647 read() when the remote end (usually a dialup) goes away. */
1649 if (smtp_accept_keepalive && !sender_host_notsocket)
1650 ip_keepalive(fileno(smtp_out), sender_host_address, FALSE);
1652 /* If the current host matches host_lookup, set the name by doing a
1653 reverse lookup. On failure, sender_host_name will be NULL and
1654 host_lookup_failed will be TRUE. This may or may not be serious - optional
1657 if (verify_check_host(&host_lookup) == OK)
1659 (void)host_name_lookup();
1660 host_build_sender_fullhost();
1663 /* Delay this until we have the full name, if it is looked up. */
1665 set_process_info("handling incoming connection from %s",
1666 host_and_ident(FALSE));
1668 /* Start up TLS if tls_on_connect is set. This is for supporting the legacy
1669 smtps port for use with older style SSL MTAs. */
1672 if (tls_on_connect &&
1673 tls_server_start(tls_require_ciphers,
1674 gnutls_require_mac, gnutls_require_kx, gnutls_require_proto) != OK)
1678 /* Test for explicit connection rejection */
1680 if (verify_check_host(&host_reject_connection) == OK)
1682 log_write(L_connection_reject, LOG_MAIN|LOG_REJECT, "refused connection "
1683 "from %s (host_reject_connection)", host_and_ident(FALSE));
1684 smtp_printf("554 SMTP service not available\r\n");
1688 /* Test with TCP Wrappers if so configured. There is a problem in that
1689 hosts_ctl() returns 0 (deny) under a number of system failure circumstances,
1690 such as disks dying. In these cases, it is desirable to reject with a 4xx
1691 error instead of a 5xx error. There isn't a "right" way to detect such
1692 problems. The following kludge is used: errno is zeroed before calling
1693 hosts_ctl(). If the result is "reject", a 5xx error is given only if the
1694 value of errno is 0 or ENOENT (which happens if /etc/hosts.{allow,deny} does
1697 #ifdef USE_TCP_WRAPPERS
1699 tcp_wrappers_name = expand_string(tcp_wrappers_daemon_name);
1700 if (tcp_wrappers_name == NULL)
1702 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "Expansion of \"%s\" "
1703 "(tcp_wrappers_name) failed: %s", string_printing(tcp_wrappers_name),
1704 expand_string_message);
1706 if (!hosts_ctl(tcp_wrappers_name,
1707 (sender_host_name == NULL)? STRING_UNKNOWN : CS sender_host_name,
1708 (sender_host_address == NULL)? STRING_UNKNOWN : CS sender_host_address,
1709 (sender_ident == NULL)? STRING_UNKNOWN : CS sender_ident))
1711 if (errno == 0 || errno == ENOENT)
1713 HDEBUG(D_receive) debug_printf("tcp wrappers rejection\n");
1714 log_write(L_connection_reject,
1715 LOG_MAIN|LOG_REJECT, "refused connection from %s "
1716 "(tcp wrappers)", host_and_ident(FALSE));
1717 smtp_printf("554 SMTP service not available\r\n");
1721 int save_errno = errno;
1722 HDEBUG(D_receive) debug_printf("tcp wrappers rejected with unexpected "
1723 "errno value %d\n", save_errno);
1724 log_write(L_connection_reject,
1725 LOG_MAIN|LOG_REJECT, "temporarily refused connection from %s "
1726 "(tcp wrappers errno=%d)", host_and_ident(FALSE), save_errno);
1727 smtp_printf("451 Temporary local problem - please try later\r\n");
1733 /* Check for reserved slots. The value of smtp_accept_count has already been
1734 incremented to include this process. */
1736 if (smtp_accept_max > 0 &&
1737 smtp_accept_count > smtp_accept_max - smtp_accept_reserve)
1739 if ((rc = verify_check_host(&smtp_reserve_hosts)) != OK)
1741 log_write(L_connection_reject,
1742 LOG_MAIN, "temporarily refused connection from %s: not in "
1743 "reserve list: connected=%d max=%d reserve=%d%s",
1744 host_and_ident(FALSE), smtp_accept_count - 1, smtp_accept_max,
1745 smtp_accept_reserve, (rc == DEFER)? " (lookup deferred)" : "");
1746 smtp_printf("421 %s: Too many concurrent SMTP connections; "
1747 "please try again later\r\n", smtp_active_hostname);
1750 reserved_host = TRUE;
1753 /* If a load level above which only messages from reserved hosts are
1754 accepted is set, check the load. For incoming calls via the daemon, the
1755 check is done in the superior process if there are no reserved hosts, to
1756 save a fork. In all cases, the load average will already be available
1757 in a global variable at this point. */
1759 if (smtp_load_reserve >= 0 &&
1760 load_average > smtp_load_reserve &&
1762 verify_check_host(&smtp_reserve_hosts) != OK)
1764 log_write(L_connection_reject,
1765 LOG_MAIN, "temporarily refused connection from %s: not in "
1766 "reserve list and load average = %.2f", host_and_ident(FALSE),
1767 (double)load_average/1000.0);
1768 smtp_printf("421 %s: Too much load; please try again later\r\n",
1769 smtp_active_hostname);
1773 /* Determine whether unqualified senders or recipients are permitted
1774 for this host. Unfortunately, we have to do this every time, in order to
1775 set the flags so that they can be inspected when considering qualifying
1776 addresses in the headers. For a site that permits no qualification, this
1777 won't take long, however. */
1779 allow_unqualified_sender =
1780 verify_check_host(&sender_unqualified_hosts) == OK;
1782 allow_unqualified_recipient =
1783 verify_check_host(&recipient_unqualified_hosts) == OK;
1785 /* Determine whether HELO/EHLO is required for this host. The requirement
1786 can be hard or soft. */
1788 helo_required = verify_check_host(&helo_verify_hosts) == OK;
1790 helo_verify = verify_check_host(&helo_try_verify_hosts) == OK;
1792 /* Determine whether this hosts is permitted to send syntactic junk
1793 after a HELO or EHLO command. */
1795 helo_accept_junk = verify_check_host(&helo_accept_junk_hosts) == OK;
1798 /* For batch SMTP input we are now done. */
1800 if (smtp_batched_input) return TRUE;
1802 /* Run the ACL if it exists */
1805 if (acl_smtp_connect != NULL)
1808 rc = acl_check(ACL_WHERE_CONNECT, NULL, acl_smtp_connect, &user_msg,
1812 (void)smtp_handle_acl_fail(ACL_WHERE_CONNECT, rc, user_msg, log_msg);
1817 /* Output the initial message for a two-way SMTP connection. It may contain
1818 newlines, which then cause a multi-line response to be given. */
1820 code = US"220"; /* Default status code */
1821 esc = US""; /* Default extended status code */
1822 esclen = 0; /* Length of esc */
1824 if (user_msg == NULL)
1826 s = expand_string(smtp_banner);
1828 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "Expansion of \"%s\" (smtp_banner) "
1829 "failed: %s", smtp_banner, expand_string_message);
1835 smtp_message_code(&code, &codelen, &s, NULL);
1839 esclen = codelen - 4;
1843 /* Remove any terminating newlines; might as well remove trailing space too */
1846 while (p > s && isspace(p[-1])) p--;
1849 /* It seems that CC:Mail is braindead, and assumes that the greeting message
1850 is all contained in a single IP packet. The original code wrote out the
1851 greeting using several calls to fprint/fputc, and on busy servers this could
1852 cause it to be split over more than one packet - which caused CC:Mail to fall
1853 over when it got the second part of the greeting after sending its first
1854 command. Sigh. To try to avoid this, build the complete greeting message
1855 first, and output it in one fell swoop. This gives a better chance of it
1856 ending up as a single packet. */
1858 ss = store_get(size);
1862 do /* At least once, in case we have an empty string */
1865 uschar *linebreak = Ustrchr(p, '\n');
1866 ss = string_cat(ss, &size, &ptr, code, 3);
1867 if (linebreak == NULL)
1870 ss = string_cat(ss, &size, &ptr, US" ", 1);
1874 len = linebreak - p;
1875 ss = string_cat(ss, &size, &ptr, US"-", 1);
1877 ss = string_cat(ss, &size, &ptr, esc, esclen);
1878 ss = string_cat(ss, &size, &ptr, p, len);
1879 ss = string_cat(ss, &size, &ptr, US"\r\n", 2);
1881 if (linebreak != NULL) p++;
1885 ss[ptr] = 0; /* string_cat leaves room for this */
1887 /* Before we write the banner, check that there is no input pending, unless
1888 this synchronisation check is disabled. */
1892 log_write(0, LOG_MAIN|LOG_REJECT, "SMTP protocol "
1893 "synchronization error (input sent without waiting for greeting): "
1894 "rejected connection from %s input=\"%s\"", host_and_ident(TRUE),
1895 string_printing(smtp_inptr));
1896 smtp_printf("554 SMTP synchronization error\r\n");
1900 /* Now output the banner */
1902 smtp_printf("%s", ss);
1910 /*************************************************
1911 * Handle SMTP syntax and protocol errors *
1912 *************************************************/
1914 /* Write to the log for SMTP syntax errors in incoming commands, if configured
1915 to do so. Then transmit the error response. The return value depends on the
1916 number of syntax and protocol errors in this SMTP session.
1919 type error type, given as a log flag bit
1920 code response code; <= 0 means don't send a response
1921 data data to reflect in the response (can be NULL)
1922 errmess the error message
1924 Returns: -1 limit of syntax/protocol errors NOT exceeded
1925 +1 limit of syntax/protocol errors IS exceeded
1927 These values fit in with the values of the "done" variable in the main
1928 processing loop in smtp_setup_msg(). */
1931 synprot_error(int type, int code, uschar *data, uschar *errmess)
1935 log_write(type, LOG_MAIN, "SMTP %s error in \"%s\" %s %s",
1936 (type == L_smtp_syntax_error)? "syntax" : "protocol",
1937 string_printing(smtp_cmd_buffer), host_and_ident(TRUE), errmess);
1939 if (++synprot_error_count > smtp_max_synprot_errors)
1942 log_write(0, LOG_MAIN|LOG_REJECT, "SMTP call from %s dropped: too many "
1943 "syntax or protocol errors (last command was \"%s\")",
1944 host_and_ident(FALSE), smtp_cmd_buffer);
1949 smtp_printf("%d%c%s%s%s\r\n", code, (yield == 1)? '-' : ' ',
1950 (data == NULL)? US"" : data, (data == NULL)? US"" : US": ", errmess);
1952 smtp_printf("%d Too many syntax or protocol errors\r\n", code);
1961 /*************************************************
1962 * Log incomplete transactions *
1963 *************************************************/
1965 /* This function is called after a transaction has been aborted by RSET, QUIT,
1966 connection drops or other errors. It logs the envelope information received
1967 so far in order to preserve address verification attempts.
1969 Argument: string to indicate what aborted the transaction
1974 incomplete_transaction_log(uschar *what)
1976 if (sender_address == NULL || /* No transaction in progress */
1977 (log_write_selector & L_smtp_incomplete_transaction) == 0 /* Not logging */
1980 /* Build list of recipients for logging */
1982 if (recipients_count > 0)
1985 raw_recipients = store_get(recipients_count * sizeof(uschar *));
1986 for (i = 0; i < recipients_count; i++)
1987 raw_recipients[i] = recipients_list[i].address;
1988 raw_recipients_count = recipients_count;
1991 log_write(L_smtp_incomplete_transaction, LOG_MAIN|LOG_SENDER|LOG_RECIPIENTS,
1992 "%s incomplete transaction (%s)", host_and_ident(TRUE), what);
1998 /*************************************************
1999 * Send SMTP response, possibly multiline *
2000 *************************************************/
2002 /* There are, it seems, broken clients out there that cannot handle multiline
2003 responses. If no_multiline_responses is TRUE (it can be set from an ACL), we
2004 output nothing for non-final calls, and only the first line for anything else.
2007 code SMTP code, may involve extended status codes
2008 codelen length of smtp code; if > 4 there's an ESC
2009 final FALSE if the last line isn't the final line
2010 msg message text, possibly containing newlines
2016 smtp_respond(uschar* code, int codelen, BOOL final, uschar *msg)
2021 if (!final && no_multiline_responses) return;
2026 esclen = codelen - 4;
2029 /* If this is the first output for a (non-batch) RCPT command, see if all RCPTs
2030 have had the same. Note: this code is also present in smtp_printf(). It would
2031 be tidier to have it only in one place, but when it was added, it was easier to
2032 do it that way, so as not to have to mess with the code for the RCPT command,
2033 which sometimes uses smtp_printf() and sometimes smtp_respond(). */
2035 if (rcpt_in_progress)
2037 if (rcpt_smtp_response == NULL)
2038 rcpt_smtp_response = string_copy(msg);
2039 else if (rcpt_smtp_response_same &&
2040 Ustrcmp(rcpt_smtp_response, msg) != 0)
2041 rcpt_smtp_response_same = FALSE;
2042 rcpt_in_progress = FALSE;
2045 /* Not output the message, splitting it up into multiple lines if necessary. */
2049 uschar *nl = Ustrchr(msg, '\n');
2052 smtp_printf("%.3s%c%.*s%s\r\n", code, final? ' ':'-', esclen, esc, msg);
2055 else if (nl[1] == 0 || no_multiline_responses)
2057 smtp_printf("%.3s%c%.*s%.*s\r\n", code, final? ' ':'-', esclen, esc,
2058 (int)(nl - msg), msg);
2063 smtp_printf("%.3s-%.*s%.*s\r\n", code, esclen, esc, (int)(nl - msg), msg);
2065 while (isspace(*msg)) msg++;
2073 /*************************************************
2074 * Parse user SMTP message *
2075 *************************************************/
2077 /* This function allows for user messages overriding the response code details
2078 by providing a suitable response code string at the start of the message
2079 user_msg. Check the message for starting with a response code and optionally an
2080 extended status code. If found, check that the first digit is valid, and if so,
2081 change the code pointer and length to use the replacement. An invalid code
2082 causes a panic log; in this case, if the log messages is the same as the user
2083 message, we must also adjust the value of the log message to show the code that
2084 is actually going to be used (the original one).
2086 This function is global because it is called from receive.c as well as within
2089 Note that the code length returned includes the terminating whitespace
2090 character, which is always included in the regex match.
2093 code SMTP code, may involve extended status codes
2094 codelen length of smtp code; if > 4 there's an ESC
2096 log_msg optional log message, to be adjusted with the new SMTP code
2102 smtp_message_code(uschar **code, int *codelen, uschar **msg, uschar **log_msg)
2107 if (msg == NULL || *msg == NULL) return;
2109 n = pcre_exec(regex_smtp_code, NULL, CS *msg, Ustrlen(*msg), 0,
2110 PCRE_EOPT, ovector, sizeof(ovector)/sizeof(int));
2113 if ((*msg)[0] != (*code)[0])
2115 log_write(0, LOG_MAIN|LOG_PANIC, "configured error code starts with "
2116 "incorrect digit (expected %c) in \"%s\"", (*code)[0], *msg);
2117 if (log_msg != NULL && *log_msg == *msg)
2118 *log_msg = string_sprintf("%s %s", *code, *log_msg + ovector[1]);
2123 *codelen = ovector[1]; /* Includes final space */
2125 *msg += ovector[1]; /* Chop the code off the message */
2132 /*************************************************
2133 * Handle an ACL failure *
2134 *************************************************/
2136 /* This function is called when acl_check() fails. As well as calls from within
2137 this module, it is called from receive.c for an ACL after DATA. It sorts out
2138 logging the incident, and sets up the error response. A message containing
2139 newlines is turned into a multiline SMTP response, but for logging, only the
2142 There's a table of default permanent failure response codes to use in
2143 globals.c, along with the table of names. VFRY is special. Despite RFC1123 it
2144 defaults disabled in Exim. However, discussion in connection with RFC 821bis
2145 (aka RFC 2821) has concluded that the response should be 252 in the disabled
2146 state, because there are broken clients that try VRFY before RCPT. A 5xx
2147 response should be given only when the address is positively known to be
2148 undeliverable. Sigh. Also, for ETRN, 458 is given on refusal, and for AUTH,
2151 From Exim 4.63, it is possible to override the response code details by
2152 providing a suitable response code string at the start of the message provided
2153 in user_msg. The code's first digit is checked for validity.
2156 where where the ACL was called from
2158 user_msg a message that can be included in an SMTP response
2159 log_msg a message for logging
2161 Returns: 0 in most cases
2162 2 if the failure code was FAIL_DROP, in which case the
2163 SMTP connection should be dropped (this value fits with the
2164 "done" variable in smtp_setup_msg() below)
2168 smtp_handle_acl_fail(int where, int rc, uschar *user_msg, uschar *log_msg)
2170 BOOL drop = rc == FAIL_DROP;
2174 uschar *sender_info = US"";
2176 #ifdef WITH_CONTENT_SCAN
2177 (where == ACL_WHERE_MIME)? US"during MIME ACL checks" :
2179 (where == ACL_WHERE_PREDATA)? US"DATA" :
2180 (where == ACL_WHERE_DATA)? US"after DATA" :
2181 (smtp_cmd_data == NULL)?
2182 string_sprintf("%s in \"connect\" ACL", acl_wherenames[where]) :
2183 string_sprintf("%s %s", acl_wherenames[where], smtp_cmd_data);
2185 if (drop) rc = FAIL;
2187 /* Set the default SMTP code, and allow a user message to change it. */
2189 smtp_code = (rc != FAIL)? US"451" : acl_wherecodes[where];
2190 smtp_message_code(&smtp_code, &codelen, &user_msg, &log_msg);
2192 /* We used to have sender_address here; however, there was a bug that was not
2193 updating sender_address after a rewrite during a verify. When this bug was
2194 fixed, sender_address at this point became the rewritten address. I'm not sure
2195 this is what should be logged, so I've changed to logging the unrewritten
2196 address to retain backward compatibility. */
2198 #ifndef WITH_CONTENT_SCAN
2199 if (where == ACL_WHERE_RCPT || where == ACL_WHERE_DATA)
2201 if (where == ACL_WHERE_RCPT || where == ACL_WHERE_DATA || where == ACL_WHERE_MIME)
2204 sender_info = string_sprintf("F=<%s>%s%s%s%s ",
2205 sender_address_unrewritten ? sender_address_unrewritten : sender_address,
2206 sender_host_authenticated ? US" A=" : US"",
2207 sender_host_authenticated ? sender_host_authenticated : US"",
2208 sender_host_authenticated && authenticated_id ? US":" : US"",
2209 sender_host_authenticated && authenticated_id ? authenticated_id : US""
2213 /* If there's been a sender verification failure with a specific message, and
2214 we have not sent a response about it yet, do so now, as a preliminary line for
2215 failures, but not defers. However, always log it for defer, and log it for fail
2216 unless the sender_verify_fail log selector has been turned off. */
2218 if (sender_verified_failed != NULL &&
2219 !testflag(sender_verified_failed, af_sverify_told))
2221 BOOL save_rcpt_in_progress = rcpt_in_progress;
2222 rcpt_in_progress = FALSE; /* So as not to treat these as the error */
2224 setflag(sender_verified_failed, af_sverify_told);
2226 if (rc != FAIL || (log_extra_selector & LX_sender_verify_fail) != 0)
2227 log_write(0, LOG_MAIN|LOG_REJECT, "%s sender verify %s for <%s>%s",
2228 host_and_ident(TRUE),
2229 ((sender_verified_failed->special_action & 255) == DEFER)? "defer":"fail",
2230 sender_verified_failed->address,
2231 (sender_verified_failed->message == NULL)? US"" :
2232 string_sprintf(": %s", sender_verified_failed->message));
2234 if (rc == FAIL && sender_verified_failed->user_message != NULL)
2235 smtp_respond(smtp_code, codelen, FALSE, string_sprintf(
2236 testflag(sender_verified_failed, af_verify_pmfail)?
2237 "Postmaster verification failed while checking <%s>\n%s\n"
2238 "Several RFCs state that you are required to have a postmaster\n"
2239 "mailbox for each mail domain. This host does not accept mail\n"
2240 "from domains whose servers reject the postmaster address."
2242 testflag(sender_verified_failed, af_verify_nsfail)?
2243 "Callback setup failed while verifying <%s>\n%s\n"
2244 "The initial connection, or a HELO or MAIL FROM:<> command was\n"
2245 "rejected. Refusing MAIL FROM:<> does not help fight spam, disregards\n"
2246 "RFC requirements, and stops you from receiving standard bounce\n"
2247 "messages. This host does not accept mail from domains whose servers\n"
2250 "Verification failed for <%s>\n%s",
2251 sender_verified_failed->address,
2252 sender_verified_failed->user_message));
2254 rcpt_in_progress = save_rcpt_in_progress;
2257 /* Sort out text for logging */
2259 log_msg = (log_msg == NULL)? US"" : string_sprintf(": %s", log_msg);
2260 lognl = Ustrchr(log_msg, '\n');
2261 if (lognl != NULL) *lognl = 0;
2263 /* Send permanent failure response to the command, but the code used isn't
2264 always a 5xx one - see comments at the start of this function. If the original
2265 rc was FAIL_DROP we drop the connection and yield 2. */
2267 if (rc == FAIL) smtp_respond(smtp_code, codelen, TRUE, (user_msg == NULL)?
2268 US"Administrative prohibition" : user_msg);
2270 /* Send temporary failure response to the command. Don't give any details,
2271 unless acl_temp_details is set. This is TRUE for a callout defer, a "defer"
2272 verb, and for a header verify when smtp_return_error_details is set.
2274 This conditional logic is all somewhat of a mess because of the odd
2275 interactions between temp_details and return_error_details. One day it should
2276 be re-implemented in a tidier fashion. */
2280 if (acl_temp_details && user_msg != NULL)
2282 if (smtp_return_error_details &&
2283 sender_verified_failed != NULL &&
2284 sender_verified_failed->message != NULL)
2286 smtp_respond(smtp_code, codelen, FALSE, sender_verified_failed->message);
2288 smtp_respond(smtp_code, codelen, TRUE, user_msg);
2291 smtp_respond(smtp_code, codelen, TRUE,
2292 US"Temporary local problem - please try later");
2295 /* Log the incident to the logs that are specified by log_reject_target
2296 (default main, reject). This can be empty to suppress logging of rejections. If
2297 the connection is not forcibly to be dropped, return 0. Otherwise, log why it
2298 is closing if required and return 2. */
2300 if (log_reject_target != 0)
2301 log_write(0, log_reject_target, "%s %s%srejected %s%s",
2302 host_and_ident(TRUE),
2303 sender_info, (rc == FAIL)? US"" : US"temporarily ", what, log_msg);
2305 if (!drop) return 0;
2307 log_write(L_smtp_connection, LOG_MAIN, "%s closed by DROP in ACL",
2308 smtp_get_connection_info());
2310 /* Run the not-quit ACL, but without any custom messages. This should not be a
2311 problem, because we get here only if some other ACL has issued "drop", and
2312 in that case, *its* custom messages will have been used above. */
2314 smtp_notquit_exit(US"acl-drop", NULL, NULL);
2321 /*************************************************
2322 * Handle SMTP exit when QUIT is not given *
2323 *************************************************/
2325 /* This function provides a logging/statistics hook for when an SMTP connection
2326 is dropped on the floor or the other end goes away. It's a global function
2327 because it's called from receive.c as well as this module. As well as running
2328 the NOTQUIT ACL, if there is one, this function also outputs a final SMTP
2329 response, either with a custom message from the ACL, or using a default. There
2330 is one case, however, when no message is output - after "drop". In that case,
2331 the ACL that obeyed "drop" has already supplied the custom message, and NULL is
2332 passed to this function.
2334 In case things go wrong while processing this function, causing an error that
2335 may re-enter this funtion, there is a recursion check.
2338 reason What $smtp_notquit_reason will be set to in the ACL;
2339 if NULL, the ACL is not run
2340 code The error code to return as part of the response
2341 defaultrespond The default message if there's no user_msg
2347 smtp_notquit_exit(uschar *reason, uschar *code, uschar *defaultrespond, ...)
2350 uschar *user_msg = NULL;
2351 uschar *log_msg = NULL;
2353 /* Check for recursive acll */
2355 if (smtp_exit_function_called)
2357 log_write(0, LOG_PANIC, "smtp_notquit_exit() called more than once (%s)",
2361 smtp_exit_function_called = TRUE;
2363 /* Call the not-QUIT ACL, if there is one, unless no reason is given. */
2365 if (acl_smtp_notquit != NULL && reason != NULL)
2367 smtp_notquit_reason = reason;
2368 rc = acl_check(ACL_WHERE_NOTQUIT, NULL, acl_smtp_notquit, &user_msg,
2371 log_write(0, LOG_MAIN|LOG_PANIC, "ACL for not-QUIT returned ERROR: %s",
2375 /* Write an SMTP response if we are expected to give one. As the default
2376 responses are all internal, they should always fit in the buffer, but code a
2377 warning, just in case. Note that string_vformat() still leaves a complete
2378 string, even if it is incomplete. */
2380 if (code != NULL && defaultrespond != NULL)
2382 if (user_msg == NULL)
2386 va_start(ap, defaultrespond);
2387 if (!string_vformat(buffer, sizeof(buffer), CS defaultrespond, ap))
2388 log_write(0, LOG_MAIN|LOG_PANIC, "string too large in smtp_notquit_exit()");
2389 smtp_printf("%s %s\r\n", code, buffer);
2393 smtp_respond(code, 3, TRUE, user_msg);
2401 /*************************************************
2402 * Verify HELO argument *
2403 *************************************************/
2405 /* This function is called if helo_verify_hosts or helo_try_verify_hosts is
2406 matched. It is also called from ACL processing if verify = helo is used and
2407 verification was not previously tried (i.e. helo_try_verify_hosts was not
2408 matched). The result of its processing is to set helo_verified and
2409 helo_verify_failed. These variables should both be FALSE for this function to
2412 Note that EHLO/HELO is legitimately allowed to quote an address literal. Allow
2413 for IPv6 ::ffff: literals.
2416 Returns: TRUE if testing was completed;
2417 FALSE on a temporary failure
2421 smtp_verify_helo(void)
2425 HDEBUG(D_receive) debug_printf("verifying EHLO/HELO argument \"%s\"\n",
2428 if (sender_helo_name == NULL)
2430 HDEBUG(D_receive) debug_printf("no EHLO/HELO command was issued\n");
2433 /* Deal with the case of -bs without an IP address */
2435 else if (sender_host_address == NULL)
2437 HDEBUG(D_receive) debug_printf("no client IP address: assume success\n");
2438 helo_verified = TRUE;
2441 /* Deal with the more common case when there is a sending IP address */
2443 else if (sender_helo_name[0] == '[')
2445 helo_verified = Ustrncmp(sender_helo_name+1, sender_host_address,
2446 Ustrlen(sender_host_address)) == 0;
2451 if (strncmpic(sender_host_address, US"::ffff:", 7) == 0)
2452 helo_verified = Ustrncmp(sender_helo_name + 1,
2453 sender_host_address + 7, Ustrlen(sender_host_address) - 7) == 0;
2458 { if (helo_verified) debug_printf("matched host address\n"); }
2461 /* Do a reverse lookup if one hasn't already given a positive or negative
2462 response. If that fails, or the name doesn't match, try checking with a forward
2467 if (sender_host_name == NULL && !host_lookup_failed)
2468 yield = host_name_lookup() != DEFER;
2470 /* If a host name is known, check it and all its aliases. */
2472 if (sender_host_name != NULL)
2474 helo_verified = strcmpic(sender_host_name, sender_helo_name) == 0;
2478 HDEBUG(D_receive) debug_printf("matched host name\n");
2482 uschar **aliases = sender_host_aliases;
2483 while (*aliases != NULL)
2485 helo_verified = strcmpic(*aliases++, sender_helo_name) == 0;
2486 if (helo_verified) break;
2491 debug_printf("matched alias %s\n", *(--aliases));
2496 /* Final attempt: try a forward lookup of the helo name */
2502 h.name = sender_helo_name;
2506 HDEBUG(D_receive) debug_printf("getting IP address for %s\n",
2508 rc = host_find_byname(&h, NULL, 0, NULL, TRUE);
2509 if (rc == HOST_FOUND || rc == HOST_FOUND_LOCAL)
2514 if (Ustrcmp(hh->address, sender_host_address) == 0)
2516 helo_verified = TRUE;
2518 debug_printf("IP address for %s matches calling address\n",
2528 if (!helo_verified) helo_verify_failed = TRUE; /* We've tried ... */
2535 /*************************************************
2536 * Send user response message *
2537 *************************************************/
2539 /* This function is passed a default response code and a user message. It calls
2540 smtp_message_code() to check and possibly modify the response code, and then
2541 calls smtp_respond() to transmit the response. I put this into a function
2542 just to avoid a lot of repetition.
2545 code the response code
2546 user_msg the user message
2552 smtp_user_msg(uschar *code, uschar *user_msg)
2555 smtp_message_code(&code, &len, &user_msg, NULL);
2556 smtp_respond(code, len, TRUE, user_msg);
2562 /*************************************************
2563 * Initialize for SMTP incoming message *
2564 *************************************************/
2566 /* This function conducts the initial dialogue at the start of an incoming SMTP
2567 message, and builds a list of recipients. However, if the incoming message
2568 is part of a batch (-bS option) a separate function is called since it would
2569 be messy having tests splattered about all over this function. This function
2570 therefore handles the case where interaction is occurring. The input and output
2571 files are set up in smtp_in and smtp_out.
2573 The global recipients_list is set to point to a vector of recipient_item
2574 blocks, whose number is given by recipients_count. This is extended by the
2575 receive_add_recipient() function. The global variable sender_address is set to
2576 the sender's address. The yield is +1 if a message has been successfully
2577 started, 0 if a QUIT command was encountered or the connection was refused from
2578 the particular host, or -1 if the connection was lost.
2582 Returns: > 0 message successfully started (reached DATA)
2583 = 0 QUIT read or end of file reached or call refused
2588 smtp_setup_msg(void)
2591 BOOL toomany = FALSE;
2592 BOOL discarded = FALSE;
2593 BOOL last_was_rej_mail = FALSE;
2594 BOOL last_was_rcpt = FALSE;
2595 void *reset_point = store_get(0);
2597 DEBUG(D_receive) debug_printf("smtp_setup_msg entered\n");
2599 /* Reset for start of new message. We allow one RSET not to be counted as a
2600 nonmail command, for those MTAs that insist on sending it between every
2601 message. Ditto for EHLO/HELO and for STARTTLS, to allow for going in and out of
2602 TLS between messages (an Exim client may do this if it has messages queued up
2603 for the host). Note: we do NOT reset AUTH at this point. */
2605 smtp_reset(reset_point);
2606 message_ended = END_NOTSTARTED;
2608 cmd_list[CMD_LIST_RSET].is_mail_cmd = TRUE;
2609 cmd_list[CMD_LIST_HELO].is_mail_cmd = TRUE;
2610 cmd_list[CMD_LIST_EHLO].is_mail_cmd = TRUE;
2612 cmd_list[CMD_LIST_STARTTLS].is_mail_cmd = TRUE;
2615 /* Set the local signal handler for SIGTERM - it tries to end off tidily */
2617 os_non_restarting_signal(SIGTERM, command_sigterm_handler);
2619 /* Batched SMTP is handled in a different function. */
2621 if (smtp_batched_input) return smtp_setup_batch_msg();
2623 /* Deal with SMTP commands. This loop is exited by setting done to a POSITIVE
2624 value. The values are 2 larger than the required yield of the function. */
2629 uschar *etrn_command;
2630 uschar *etrn_serialize_key;
2632 uschar *log_msg, *smtp_code;
2633 uschar *user_msg = NULL;
2634 uschar *recipient = NULL;
2635 uschar *hello = NULL;
2636 uschar *set_id = NULL;
2638 BOOL was_rej_mail = FALSE;
2639 BOOL was_rcpt = FALSE;
2640 void (*oldsignal)(int);
2642 int start, end, sender_domain, recipient_domain;
2647 switch(smtp_read_command(TRUE))
2649 /* The AUTH command is not permitted to occur inside a transaction, and may
2650 occur successfully only once per connection. Actually, that isn't quite
2651 true. When TLS is started, all previous information about a connection must
2652 be discarded, so a new AUTH is permitted at that time.
2654 AUTH may only be used when it has been advertised. However, it seems that
2655 there are clients that send AUTH when it hasn't been advertised, some of
2656 them even doing this after HELO. And there are MTAs that accept this. Sigh.
2657 So there's a get-out that allows this to happen.
2659 AUTH is initially labelled as a "nonmail command" so that one occurrence
2660 doesn't get counted. We change the label here so that multiple failing
2661 AUTHS will eventually hit the nonmail threshold. */
2665 authentication_failed = TRUE;
2666 cmd_list[CMD_LIST_AUTH].is_mail_cmd = FALSE;
2668 if (!auth_advertised && !allow_auth_unadvertised)
2670 done = synprot_error(L_smtp_protocol_error, 503, NULL,
2671 US"AUTH command used when not advertised");
2674 if (sender_host_authenticated != NULL)
2676 done = synprot_error(L_smtp_protocol_error, 503, NULL,
2677 US"already authenticated");
2680 if (sender_address != NULL)
2682 done = synprot_error(L_smtp_protocol_error, 503, NULL,
2683 US"not permitted in mail transaction");
2689 if (acl_smtp_auth != NULL)
2691 rc = acl_check(ACL_WHERE_AUTH, NULL, acl_smtp_auth, &user_msg, &log_msg);
2694 done = smtp_handle_acl_fail(ACL_WHERE_AUTH, rc, user_msg, log_msg);
2699 /* Find the name of the requested authentication mechanism. */
2702 while ((c = *smtp_cmd_data) != 0 && !isspace(c))
2704 if (!isalnum(c) && c != '-' && c != '_')
2706 done = synprot_error(L_smtp_syntax_error, 501, NULL,
2707 US"invalid character in authentication mechanism name");
2713 /* If not at the end of the line, we must be at white space. Terminate the
2714 name and move the pointer on to any data that may be present. */
2716 if (*smtp_cmd_data != 0)
2718 *smtp_cmd_data++ = 0;
2719 while (isspace(*smtp_cmd_data)) smtp_cmd_data++;
2722 /* Search for an authentication mechanism which is configured for use
2723 as a server and which has been advertised (unless, sigh, allow_auth_
2724 unadvertised is set). */
2726 for (au = auths; au != NULL; au = au->next)
2728 if (strcmpic(s, au->public_name) == 0 && au->server &&
2729 (au->advertised || allow_auth_unadvertised)) break;
2734 done = synprot_error(L_smtp_protocol_error, 504, NULL,
2735 string_sprintf("%s authentication mechanism not supported", s));
2739 /* Run the checking code, passing the remainder of the command line as
2740 data. Initials the $auth<n> variables as empty. Initialize $0 empty and set
2741 it as the only set numerical variable. The authenticator may set $auth<n>
2742 and also set other numeric variables. The $auth<n> variables are preferred
2743 nowadays; the numerical variables remain for backwards compatibility.
2745 Afterwards, have a go at expanding the set_id string, even if
2746 authentication failed - for bad passwords it can be useful to log the
2747 userid. On success, require set_id to expand and exist, and put it in
2748 authenticated_id. Save this in permanent store, as the working store gets
2749 reset at HELO, RSET, etc. */
2751 for (i = 0; i < AUTH_VARS; i++) auth_vars[i] = NULL;
2753 expand_nlength[0] = 0; /* $0 contains nothing */
2755 c = (au->info->servercode)(au, smtp_cmd_data);
2756 if (au->set_id != NULL) set_id = expand_string(au->set_id);
2757 expand_nmax = -1; /* Reset numeric variables */
2758 for (i = 0; i < AUTH_VARS; i++) auth_vars[i] = NULL; /* Reset $auth<n> */
2760 /* The value of authenticated_id is stored in the spool file and printed in
2761 log lines. It must not contain binary zeros or newline characters. In
2762 normal use, it never will, but when playing around or testing, this error
2763 can (did) happen. To guard against this, ensure that the id contains only
2764 printing characters. */
2766 if (set_id != NULL) set_id = string_printing(set_id);
2768 /* For the non-OK cases, set up additional logging data if set_id
2773 if (set_id != NULL && *set_id != 0)
2774 set_id = string_sprintf(" (set_id=%s)", set_id);
2778 /* Switch on the result */
2783 if (au->set_id == NULL || set_id != NULL) /* Complete success */
2785 if (set_id != NULL) authenticated_id = string_copy_malloc(set_id);
2786 sender_host_authenticated = au->name;
2787 authentication_failed = FALSE;
2789 protocols[pextend + pauthed + ((tls_active >= 0)? pcrpted:0)] +
2790 ((sender_host_address != NULL)? pnlocal : 0);
2791 s = ss = US"235 Authentication succeeded";
2792 authenticated_by = au;
2796 /* Authentication succeeded, but we failed to expand the set_id string.
2797 Treat this as a temporary error. */
2799 auth_defer_msg = expand_string_message;
2803 s = string_sprintf("435 Unable to authenticate at present%s",
2804 auth_defer_user_msg);
2805 ss = string_sprintf("435 Unable to authenticate at present%s: %s",
2806 set_id, auth_defer_msg);
2810 s = ss = US"501 Invalid base64 data";
2814 s = ss = US"501 Authentication cancelled";
2818 s = ss = US"553 Initial data not expected";
2822 s = US"535 Incorrect authentication data";
2823 ss = string_sprintf("535 Incorrect authentication data%s", set_id);
2827 s = US"435 Internal error";
2828 ss = string_sprintf("435 Internal error%s: return %d from authentication "
2829 "check", set_id, c);
2833 smtp_printf("%s\r\n", s);
2835 log_write(0, LOG_MAIN|LOG_REJECT, "%s authenticator failed for %s: %s",
2836 au->name, host_and_ident(FALSE), ss);
2838 break; /* AUTH_CMD */
2840 /* The HELO/EHLO commands are permitted to appear in the middle of a
2841 session as well as at the beginning. They have the effect of a reset in
2842 addition to their other functions. Their absence at the start cannot be
2843 taken to be an error.
2847 If the EHLO command is not acceptable to the SMTP server, 501, 500,
2848 or 502 failure replies MUST be returned as appropriate. The SMTP
2849 server MUST stay in the same state after transmitting these replies
2850 that it was in before the EHLO was received.
2852 Therefore, we do not do the reset until after checking the command for
2853 acceptability. This change was made for Exim release 4.11. Previously
2854 it did the reset first. */
2867 HELO_EHLO: /* Common code for HELO and EHLO */
2868 cmd_list[CMD_LIST_HELO].is_mail_cmd = FALSE;
2869 cmd_list[CMD_LIST_EHLO].is_mail_cmd = FALSE;
2871 /* Reject the HELO if its argument was invalid or non-existent. A
2872 successful check causes the argument to be saved in malloc store. */
2874 if (!check_helo(smtp_cmd_data))
2876 smtp_printf("501 Syntactically invalid %s argument(s)\r\n", hello);
2878 log_write(0, LOG_MAIN|LOG_REJECT, "rejected %s from %s: syntactically "
2879 "invalid argument(s): %s", hello, host_and_ident(FALSE),
2880 (*smtp_cmd_argument == 0)? US"(no argument given)" :
2881 string_printing(smtp_cmd_argument));
2883 if (++synprot_error_count > smtp_max_synprot_errors)
2885 log_write(0, LOG_MAIN|LOG_REJECT, "SMTP call from %s dropped: too many "
2886 "syntax or protocol errors (last command was \"%s\")",
2887 host_and_ident(FALSE), smtp_cmd_buffer);
2894 /* If sender_host_unknown is true, we have got here via the -bs interface,
2895 not called from inetd. Otherwise, we are running an IP connection and the
2896 host address will be set. If the helo name is the primary name of this
2897 host and we haven't done a reverse lookup, force one now. If helo_required
2898 is set, ensure that the HELO name matches the actual host. If helo_verify
2899 is set, do the same check, but softly. */
2901 if (!sender_host_unknown)
2903 BOOL old_helo_verified = helo_verified;
2904 uschar *p = smtp_cmd_data;
2906 while (*p != 0 && !isspace(*p)) { *p = tolower(*p); p++; }
2909 /* Force a reverse lookup if HELO quoted something in helo_lookup_domains
2910 because otherwise the log can be confusing. */
2912 if (sender_host_name == NULL &&
2913 (deliver_domain = sender_helo_name, /* set $domain */
2914 match_isinlist(sender_helo_name, &helo_lookup_domains, 0,
2915 &domainlist_anchor, NULL, MCL_DOMAIN, TRUE, NULL)) == OK)
2916 (void)host_name_lookup();
2918 /* Rebuild the fullhost info to include the HELO name (and the real name
2919 if it was looked up.) */
2921 host_build_sender_fullhost(); /* Rebuild */
2922 set_process_info("handling%s incoming connection from %s",
2923 (tls_active >= 0)? " TLS" : "", host_and_ident(FALSE));
2925 /* Verify if configured. This doesn't give much security, but it does
2926 make some people happy to be able to do it. If helo_required is set,
2927 (host matches helo_verify_hosts) failure forces rejection. If helo_verify
2928 is set (host matches helo_try_verify_hosts), it does not. This is perhaps
2929 now obsolescent, since the verification can now be requested selectively
2932 helo_verified = helo_verify_failed = FALSE;
2933 if (helo_required || helo_verify)
2935 BOOL tempfail = !smtp_verify_helo();
2940 smtp_printf("%d %s argument does not match calling host\r\n",
2941 tempfail? 451 : 550, hello);
2942 log_write(0, LOG_MAIN|LOG_REJECT, "%srejected \"%s %s\" from %s",
2943 tempfail? "temporarily " : "",
2944 hello, sender_helo_name, host_and_ident(FALSE));
2945 helo_verified = old_helo_verified;
2946 break; /* End of HELO/EHLO processing */
2948 HDEBUG(D_all) debug_printf("%s verification failed but host is in "
2949 "helo_try_verify_hosts\n", hello);
2954 #ifdef EXPERIMENTAL_SPF
2955 /* set up SPF context */
2956 spf_init(sender_helo_name, sender_host_address);
2959 /* Apply an ACL check if one is defined; afterwards, recheck
2960 synchronization in case the client started sending in a delay. */
2962 if (acl_smtp_helo != NULL)
2964 rc = acl_check(ACL_WHERE_HELO, NULL, acl_smtp_helo, &user_msg, &log_msg);
2967 done = smtp_handle_acl_fail(ACL_WHERE_HELO, rc, user_msg, log_msg);
2968 sender_helo_name = NULL;
2969 host_build_sender_fullhost(); /* Rebuild */
2972 else if (!check_sync()) goto SYNC_FAILURE;
2975 /* Generate an OK reply. The default string includes the ident if present,
2976 and also the IP address if present. Reflecting back the ident is intended
2977 as a deterrent to mail forgers. For maximum efficiency, and also because
2978 some broken systems expect each response to be in a single packet, arrange
2979 that the entire reply is sent in one write(). */
2981 auth_advertised = FALSE;
2982 pipelining_advertised = FALSE;
2984 tls_advertised = FALSE;
2987 smtp_code = US"250 "; /* Default response code plus space*/
2988 if (user_msg == NULL)
2990 s = string_sprintf("%.3s %s Hello %s%s%s",
2992 smtp_active_hostname,
2993 (sender_ident == NULL)? US"" : sender_ident,
2994 (sender_ident == NULL)? US"" : US" at ",
2995 (sender_host_name == NULL)? sender_helo_name : sender_host_name);
3000 if (sender_host_address != NULL)
3002 s = string_cat(s, &size, &ptr, US" [", 2);
3003 s = string_cat(s, &size, &ptr, sender_host_address,
3004 Ustrlen(sender_host_address));
3005 s = string_cat(s, &size, &ptr, US"]", 1);
3009 /* A user-supplied EHLO greeting may not contain more than one line. Note
3010 that the code returned by smtp_message_code() includes the terminating
3011 whitespace character. */
3017 smtp_message_code(&smtp_code, &codelen, &user_msg, NULL);
3018 s = string_sprintf("%.*s%s", codelen, smtp_code, user_msg);
3019 if ((ss = strpbrk(CS s, "\r\n")) != NULL)
3021 log_write(0, LOG_MAIN|LOG_PANIC, "EHLO/HELO response must not contain "
3022 "newlines: message truncated: %s", string_printing(s));
3029 s = string_cat(s, &size, &ptr, US"\r\n", 2);
3031 /* If we received EHLO, we must create a multiline response which includes
3032 the functions supported. */
3038 /* I'm not entirely happy with this, as an MTA is supposed to check
3039 that it has enough room to accept a message of maximum size before
3040 it sends this. However, there seems little point in not sending it.
3041 The actual size check happens later at MAIL FROM time. By postponing it
3042 till then, VRFY and EXPN can be used after EHLO when space is short. */
3044 if (thismessage_size_limit > 0)
3046 sprintf(CS big_buffer, "%.3s-SIZE %d\r\n", smtp_code,
3047 thismessage_size_limit);
3048 s = string_cat(s, &size, &ptr, big_buffer, Ustrlen(big_buffer));
3052 s = string_cat(s, &size, &ptr, smtp_code, 3);
3053 s = string_cat(s, &size, &ptr, US"-SIZE\r\n", 7);
3056 /* Exim does not do protocol conversion or data conversion. It is 8-bit
3057 clean; if it has an 8-bit character in its hand, it just sends it. It
3058 cannot therefore specify 8BITMIME and remain consistent with the RFCs.
3059 However, some users want this option simply in order to stop MUAs
3060 mangling messages that contain top-bit-set characters. It is therefore
3061 provided as an option. */
3063 if (accept_8bitmime)
3065 s = string_cat(s, &size, &ptr, smtp_code, 3);
3066 s = string_cat(s, &size, &ptr, US"-8BITMIME\r\n", 11);
3069 /* Advertise ETRN if there's an ACL checking whether a host is
3070 permitted to issue it; a check is made when any host actually tries. */
3072 if (acl_smtp_etrn != NULL)
3074 s = string_cat(s, &size, &ptr, smtp_code, 3);
3075 s = string_cat(s, &size, &ptr, US"-ETRN\r\n", 7);
3078 /* Advertise EXPN if there's an ACL checking whether a host is
3079 permitted to issue it; a check is made when any host actually tries. */
3081 if (acl_smtp_expn != NULL)
3083 s = string_cat(s, &size, &ptr, smtp_code, 3);
3084 s = string_cat(s, &size, &ptr, US"-EXPN\r\n", 7);
3087 /* Exim is quite happy with pipelining, so let the other end know that
3088 it is safe to use it, unless advertising is disabled. */
3090 if (pipelining_enable &&
3091 verify_check_host(&pipelining_advertise_hosts) == OK)
3093 s = string_cat(s, &size, &ptr, smtp_code, 3);
3094 s = string_cat(s, &size, &ptr, US"-PIPELINING\r\n", 13);
3095 sync_cmd_limit = NON_SYNC_CMD_PIPELINING;
3096 pipelining_advertised = TRUE;
3099 /* If any server authentication mechanisms are configured, advertise
3100 them if the current host is in auth_advertise_hosts. The problem with
3101 advertising always is that some clients then require users to
3102 authenticate (and aren't configurable otherwise) even though it may not
3103 be necessary (e.g. if the host is in host_accept_relay).
3105 RFC 2222 states that SASL mechanism names contain only upper case
3106 letters, so output the names in upper case, though we actually recognize
3107 them in either case in the AUTH command. */
3111 if (verify_check_host(&auth_advertise_hosts) == OK)
3115 for (au = auths; au != NULL; au = au->next)
3117 if (au->server && (au->advertise_condition == NULL ||
3118 expand_check_condition(au->advertise_condition, au->name,
3119 US"authenticator")))
3124 s = string_cat(s, &size, &ptr, smtp_code, 3);
3125 s = string_cat(s, &size, &ptr, US"-AUTH", 5);
3127 auth_advertised = TRUE;
3130 s = string_cat(s, &size, &ptr, US" ", 1);
3131 s = string_cat(s, &size, &ptr, au->public_name,
3132 Ustrlen(au->public_name));
3133 while (++saveptr < ptr) s[saveptr] = toupper(s[saveptr]);
3134 au->advertised = TRUE;
3136 else au->advertised = FALSE;
3138 if (!first) s = string_cat(s, &size, &ptr, US"\r\n", 2);
3142 /* Advertise TLS (Transport Level Security) aka SSL (Secure Socket Layer)
3143 if it has been included in the binary, and the host matches
3144 tls_advertise_hosts. We must *not* advertise if we are already in a
3145 secure connection. */
3148 if (tls_active < 0 &&
3149 verify_check_host(&tls_advertise_hosts) != FAIL)
3151 s = string_cat(s, &size, &ptr, smtp_code, 3);
3152 s = string_cat(s, &size, &ptr, US"-STARTTLS\r\n", 11);
3153 tls_advertised = TRUE;
3157 /* Finish off the multiline reply with one that is always available. */
3159 s = string_cat(s, &size, &ptr, smtp_code, 3);
3160 s = string_cat(s, &size, &ptr, US" HELP\r\n", 7);
3163 /* Terminate the string (for debug), write it, and note that HELO/EHLO
3169 if (tls_active >= 0) (void)tls_write(s, ptr); else
3172 (void)fwrite(s, 1, ptr, smtp_out);
3176 while ((cr = Ustrchr(s, '\r')) != NULL) /* lose CRs */
3177 memmove(cr, cr + 1, (ptr--) - (cr - s));
3178 debug_printf("SMTP>> %s", s);
3182 /* Reset the protocol and the state, abandoning any previous message. */
3184 received_protocol = (esmtp?
3186 ((sender_host_authenticated != NULL)? pauthed : 0) +
3187 ((tls_active >= 0)? pcrpted : 0)]
3189 protocols[pnormal + ((tls_active >= 0)? pcrpted : 0)])
3191 ((sender_host_address != NULL)? pnlocal : 0);
3193 smtp_reset(reset_point);
3195 break; /* HELO/EHLO */
3198 /* The MAIL command requires an address as an operand. All we do
3199 here is to parse it for syntactic correctness. The form "<>" is
3200 a special case which converts into an empty string. The start/end
3201 pointers in the original are not used further for this address, as
3202 it is the canonical extracted address which is all that is kept. */
3206 smtp_mailcmd_count++; /* Count for limit and ratelimit */
3207 was_rej_mail = TRUE; /* Reset if accepted */
3209 if (helo_required && !helo_seen)
3211 smtp_printf("503 HELO or EHLO required\r\n");
3212 log_write(0, LOG_MAIN|LOG_REJECT, "rejected MAIL from %s: no "
3213 "HELO/EHLO given", host_and_ident(FALSE));
3217 if (sender_address != NULL)
3219 done = synprot_error(L_smtp_protocol_error, 503, NULL,
3220 US"sender already given");
3224 if (smtp_cmd_data[0] == 0)
3226 done = synprot_error(L_smtp_protocol_error, 501, NULL,
3227 US"MAIL must have an address operand");
3231 /* Check to see if the limit for messages per connection would be
3232 exceeded by accepting further messages. */
3234 if (smtp_accept_max_per_connection > 0 &&
3235 smtp_mailcmd_count > smtp_accept_max_per_connection)
3237 smtp_printf("421 too many messages in this connection\r\n");
3238 log_write(0, LOG_MAIN|LOG_REJECT, "rejected MAIL command %s: too many "
3239 "messages in one connection", host_and_ident(TRUE));
3243 /* Reset for start of message - even if this is going to fail, we
3244 obviously need to throw away any previous data. */
3246 smtp_reset(reset_point);
3248 sender_data = recipient_data = NULL;
3250 /* Loop, checking for ESMTP additions to the MAIL FROM command. */
3254 uschar *name, *value, *end;
3255 unsigned long int size;
3257 if (!extract_option(&name, &value)) break;
3259 /* Handle SIZE= by reading the value. We don't do the check till later,
3260 in order to be able to log the sender address on failure. */
3262 if (strcmpic(name, US"SIZE") == 0 &&
3263 ((size = Ustrtoul(value, &end, 10)), *end == 0))
3265 if ((size == ULONG_MAX && errno == ERANGE) || size > INT_MAX)
3267 message_size = (int)size;
3270 /* If this session was initiated with EHLO and accept_8bitmime is set,
3271 Exim will have indicated that it supports the BODY=8BITMIME option. In
3272 fact, it does not support this according to the RFCs, in that it does not
3273 take any special action for forwarding messages containing 8-bit
3274 characters. That is why accept_8bitmime is not the default setting, but
3275 some sites want the action that is provided. We recognize both "8BITMIME"
3276 and "7BIT" as body types, but take no action. */
3278 else if (accept_8bitmime && strcmpic(name, US"BODY") == 0 &&
3279 (strcmpic(value, US"8BITMIME") == 0 ||
3280 strcmpic(value, US"7BIT") == 0)) {}
3282 /* Handle the AUTH extension. If the value given is not "<>" and either
3283 the ACL says "yes" or there is no ACL but the sending host is
3284 authenticated, we set it up as the authenticated sender. However, if the
3285 authenticator set a condition to be tested, we ignore AUTH on MAIL unless
3286 the condition is met. The value of AUTH is an xtext, which means that +,
3287 = and cntrl chars are coded in hex; however "<>" is unaffected by this
3290 else if (strcmpic(name, US"AUTH") == 0)
3292 if (Ustrcmp(value, "<>") != 0)
3297 if (auth_xtextdecode(value, &authenticated_sender) < 0)
3299 /* Put back terminator overrides for error message */
3302 done = synprot_error(L_smtp_syntax_error, 501, NULL,
3303 US"invalid data for AUTH");
3307 if (acl_smtp_mailauth == NULL)
3309 ignore_msg = US"client not authenticated";
3310 rc = (sender_host_authenticated != NULL)? OK : FAIL;
3314 ignore_msg = US"rejected by ACL";
3315 rc = acl_check(ACL_WHERE_MAILAUTH, NULL, acl_smtp_mailauth,
3316 &user_msg, &log_msg);
3322 if (authenticated_by == NULL ||
3323 authenticated_by->mail_auth_condition == NULL ||
3324 expand_check_condition(authenticated_by->mail_auth_condition,
3325 authenticated_by->name, US"authenticator"))
3326 break; /* Accept the AUTH */
3328 ignore_msg = US"server_mail_auth_condition failed";
3329 if (authenticated_id != NULL)
3330 ignore_msg = string_sprintf("%s: authenticated ID=\"%s\"",
3331 ignore_msg, authenticated_id);
3336 authenticated_sender = NULL;
3337 log_write(0, LOG_MAIN, "ignoring AUTH=%s from %s (%s)",
3338 value, host_and_ident(TRUE), ignore_msg);
3341 /* Should only get DEFER or ERROR here. Put back terminator
3342 overrides for error message */
3347 (void)smtp_handle_acl_fail(ACL_WHERE_MAILAUTH, rc, user_msg,
3354 /* Unknown option. Stick back the terminator characters and break
3355 the loop. An error for a malformed address will occur. */
3365 /* If we have passed the threshold for rate limiting, apply the current
3366 delay, and update it for next time, provided this is a limited host. */
3368 if (smtp_mailcmd_count > smtp_rlm_threshold &&
3369 verify_check_host(&smtp_ratelimit_hosts) == OK)
3371 DEBUG(D_receive) debug_printf("rate limit MAIL: delay %.3g sec\n",
3372 smtp_delay_mail/1000.0);
3373 millisleep((int)smtp_delay_mail);
3374 smtp_delay_mail *= smtp_rlm_factor;
3375 if (smtp_delay_mail > (double)smtp_rlm_limit)
3376 smtp_delay_mail = (double)smtp_rlm_limit;
3379 /* Now extract the address, first applying any SMTP-time rewriting. The
3380 TRUE flag allows "<>" as a sender address. */
3382 raw_sender = ((rewrite_existflags & rewrite_smtp) != 0)?
3383 rewrite_one(smtp_cmd_data, rewrite_smtp, NULL, FALSE, US"",
3384 global_rewrite_rules) : smtp_cmd_data;
3386 /* rfc821_domains = TRUE; << no longer needed */
3388 parse_extract_address(raw_sender, &errmess, &start, &end, &sender_domain,
3390 /* rfc821_domains = FALSE; << no longer needed */
3392 if (raw_sender == NULL)
3394 done = synprot_error(L_smtp_syntax_error, 501, smtp_cmd_data, errmess);
3398 sender_address = raw_sender;
3400 /* If there is a configured size limit for mail, check that this message
3401 doesn't exceed it. The check is postponed to this point so that the sender
3404 if (thismessage_size_limit > 0 && message_size > thismessage_size_limit)
3406 smtp_printf("552 Message size exceeds maximum permitted\r\n");
3407 log_write(L_size_reject,
3408 LOG_MAIN|LOG_REJECT, "rejected MAIL FROM:<%s> %s: "
3409 "message too big: size%s=%d max=%d",
3411 host_and_ident(TRUE),
3412 (message_size == INT_MAX)? ">" : "",
3414 thismessage_size_limit);
3415 sender_address = NULL;
3419 /* Check there is enough space on the disk unless configured not to.
3420 When smtp_check_spool_space is set, the check is for thismessage_size_limit
3421 plus the current message - i.e. we accept the message only if it won't
3422 reduce the space below the threshold. Add 5000 to the size to allow for
3423 overheads such as the Received: line and storing of recipients, etc.
3424 By putting the check here, even when SIZE is not given, it allow VRFY
3425 and EXPN etc. to be used when space is short. */
3427 if (!receive_check_fs(
3428 (smtp_check_spool_space && message_size >= 0)?
3429 message_size + 5000 : 0))
3431 smtp_printf("452 Space shortage, please try later\r\n");
3432 sender_address = NULL;
3436 /* If sender_address is unqualified, reject it, unless this is a locally
3437 generated message, or the sending host or net is permitted to send
3438 unqualified addresses - typically local machines behaving as MUAs -
3439 in which case just qualify the address. The flag is set above at the start
3440 of the SMTP connection. */
3442 if (sender_domain == 0 && sender_address[0] != 0)
3444 if (allow_unqualified_sender)
3446 sender_domain = Ustrlen(sender_address) + 1;
3447 sender_address = rewrite_address_qualify(sender_address, FALSE);
3448 DEBUG(D_receive) debug_printf("unqualified address %s accepted\n",
3453 smtp_printf("501 %s: sender address must contain a domain\r\n",
3455 log_write(L_smtp_syntax_error,
3456 LOG_MAIN|LOG_REJECT,
3457 "unqualified sender rejected: <%s> %s%s",
3459 host_and_ident(TRUE),
3461 sender_address = NULL;
3466 /* Apply an ACL check if one is defined, before responding. Afterwards,
3467 when pipelining is not advertised, do another sync check in case the ACL
3468 delayed and the client started sending in the meantime. */
3470 if (acl_smtp_mail == NULL) rc = OK; else
3472 rc = acl_check(ACL_WHERE_MAIL, NULL, acl_smtp_mail, &user_msg, &log_msg);
3473 if (rc == OK && !pipelining_advertised && !check_sync())
3477 if (rc == OK || rc == DISCARD)
3479 if (user_msg == NULL) smtp_printf("250 OK\r\n");
3480 else smtp_user_msg(US"250", user_msg);
3481 smtp_delay_rcpt = smtp_rlr_base;
3482 recipients_discarded = (rc == DISCARD);
3483 was_rej_mail = FALSE;
3487 done = smtp_handle_acl_fail(ACL_WHERE_MAIL, rc, user_msg, log_msg);
3488 sender_address = NULL;
3493 /* The RCPT command requires an address as an operand. There may be any
3494 number of RCPT commands, specifying multiple recipients. We build them all
3495 into a data structure. The start/end values given by parse_extract_address
3496 are not used, as we keep only the extracted address. */
3501 was_rcpt = rcpt_in_progress = TRUE;
3503 /* There must be a sender address; if the sender was rejected and
3504 pipelining was advertised, we assume the client was pipelining, and do not
3505 count this as a protocol error. Reset was_rej_mail so that further RCPTs
3506 get the same treatment. */
3508 if (sender_address == NULL)
3510 if (pipelining_advertised && last_was_rej_mail)
3512 smtp_printf("503 sender not yet given\r\n");
3513 was_rej_mail = TRUE;
3517 done = synprot_error(L_smtp_protocol_error, 503, NULL,
3518 US"sender not yet given");
3519 was_rcpt = FALSE; /* Not a valid RCPT */
3525 /* Check for an operand */
3527 if (smtp_cmd_data[0] == 0)
3529 done = synprot_error(L_smtp_syntax_error, 501, NULL,
3530 US"RCPT must have an address operand");
3535 /* Apply SMTP rewriting then extract the working address. Don't allow "<>"
3536 as a recipient address */
3538 recipient = ((rewrite_existflags & rewrite_smtp) != 0)?
3539 rewrite_one(smtp_cmd_data, rewrite_smtp, NULL, FALSE, US"",
3540 global_rewrite_rules) : smtp_cmd_data;
3542 /* rfc821_domains = TRUE; << no longer needed */
3543 recipient = parse_extract_address(recipient, &errmess, &start, &end,
3544 &recipient_domain, FALSE);
3545 /* rfc821_domains = FALSE; << no longer needed */
3547 if (recipient == NULL)
3549 done = synprot_error(L_smtp_syntax_error, 501, smtp_cmd_data, errmess);
3554 /* If the recipient address is unqualified, reject it, unless this is a
3555 locally generated message. However, unqualified addresses are permitted
3556 from a configured list of hosts and nets - typically when behaving as
3557 MUAs rather than MTAs. Sad that SMTP is used for both types of traffic,
3558 really. The flag is set at the start of the SMTP connection.
3560 RFC 1123 talks about supporting "the reserved mailbox postmaster"; I always
3561 assumed this meant "reserved local part", but the revision of RFC 821 and
3562 friends now makes it absolutely clear that it means *mailbox*. Consequently
3563 we must always qualify this address, regardless. */
3565 if (recipient_domain == 0)
3567 if (allow_unqualified_recipient ||
3568 strcmpic(recipient, US"postmaster") == 0)
3570 DEBUG(D_receive) debug_printf("unqualified address %s accepted\n",
3572 recipient_domain = Ustrlen(recipient) + 1;
3573 recipient = rewrite_address_qualify(recipient, TRUE);
3578 smtp_printf("501 %s: recipient address must contain a domain\r\n",
3580 log_write(L_smtp_syntax_error,
3581 LOG_MAIN|LOG_REJECT, "unqualified recipient rejected: "
3582 "<%s> %s%s", recipient, host_and_ident(TRUE),
3588 /* Check maximum allowed */
3590 if (rcpt_count > recipients_max && recipients_max > 0)
3592 if (recipients_max_reject)
3595 smtp_printf("552 too many recipients\r\n");
3597 log_write(0, LOG_MAIN|LOG_REJECT, "too many recipients: message "
3598 "rejected: sender=<%s> %s", sender_address, host_and_ident(TRUE));
3603 smtp_printf("452 too many recipients\r\n");
3605 log_write(0, LOG_MAIN|LOG_REJECT, "too many recipients: excess "
3606 "temporarily rejected: sender=<%s> %s", sender_address,
3607 host_and_ident(TRUE));
3614 /* If we have passed the threshold for rate limiting, apply the current
3615 delay, and update it for next time, provided this is a limited host. */
3617 if (rcpt_count > smtp_rlr_threshold &&
3618 verify_check_host(&smtp_ratelimit_hosts) == OK)
3620 DEBUG(D_receive) debug_printf("rate limit RCPT: delay %.3g sec\n",
3621 smtp_delay_rcpt/1000.0);
3622 millisleep((int)smtp_delay_rcpt);
3623 smtp_delay_rcpt *= smtp_rlr_factor;
3624 if (smtp_delay_rcpt > (double)smtp_rlr_limit)
3625 smtp_delay_rcpt = (double)smtp_rlr_limit;
3628 /* If the MAIL ACL discarded all the recipients, we bypass ACL checking
3629 for them. Otherwise, check the access control list for this recipient. As
3630 there may be a delay in this, re-check for a synchronization error
3631 afterwards, unless pipelining was advertised. */
3633 if (recipients_discarded) rc = DISCARD; else
3635 rc = acl_check(ACL_WHERE_RCPT, recipient, acl_smtp_rcpt, &user_msg,
3637 if (rc == OK && !pipelining_advertised && !check_sync())
3641 /* The ACL was happy */
3645 if (user_msg == NULL) smtp_printf("250 Accepted\r\n");
3646 else smtp_user_msg(US"250", user_msg);
3647 receive_add_recipient(recipient, -1);
3650 /* The recipient was discarded */
3652 else if (rc == DISCARD)
3654 if (user_msg == NULL) smtp_printf("250 Accepted\r\n");
3655 else smtp_user_msg(US"250", user_msg);
3658 log_write(0, LOG_MAIN|LOG_REJECT, "%s F=<%s> rejected RCPT %s: "
3659 "discarded by %s ACL%s%s", host_and_ident(TRUE),
3660 (sender_address_unrewritten != NULL)?
3661 sender_address_unrewritten : sender_address,
3662 smtp_cmd_argument, recipients_discarded? "MAIL" : "RCPT",
3663 (log_msg == NULL)? US"" : US": ",
3664 (log_msg == NULL)? US"" : log_msg);
3667 /* Either the ACL failed the address, or it was deferred. */
3671 if (rc == FAIL) rcpt_fail_count++; else rcpt_defer_count++;
3672 done = smtp_handle_acl_fail(ACL_WHERE_RCPT, rc, user_msg, log_msg);
3677 /* The DATA command is legal only if it follows successful MAIL FROM
3678 and RCPT TO commands. However, if pipelining is advertised, a bad DATA is
3679 not counted as a protocol error if it follows RCPT (which must have been
3680 rejected if there are no recipients.) This function is complete when a
3681 valid DATA command is encountered.
3683 Note concerning the code used: RFC 2821 says this:
3685 - If there was no MAIL, or no RCPT, command, or all such commands
3686 were rejected, the server MAY return a "command out of sequence"
3687 (503) or "no valid recipients" (554) reply in response to the
3690 The example in the pipelining RFC 2920 uses 554, but I use 503 here
3691 because it is the same whether pipelining is in use or not.
3693 If all the RCPT commands that precede DATA provoked the same error message
3694 (often indicating some kind of system error), it is helpful to include it
3695 with the DATA rejection (an idea suggested by Tony Finch). */
3699 if (!discarded && recipients_count <= 0)
3701 if (rcpt_smtp_response_same && rcpt_smtp_response != NULL)
3703 uschar *code = US"503";
3704 int len = Ustrlen(rcpt_smtp_response);
3705 smtp_respond(code, 3, FALSE, US"All RCPT commands were rejected with "
3707 /* Responses from smtp_printf() will have \r\n on the end */
3708 if (len > 2 && rcpt_smtp_response[len-2] == '\r')
3709 rcpt_smtp_response[len-2] = 0;
3710 smtp_respond(code, 3, FALSE, rcpt_smtp_response);
3712 if (pipelining_advertised && last_was_rcpt)
3713 smtp_printf("503 Valid RCPT command must precede DATA\r\n");
3715 done = synprot_error(L_smtp_protocol_error, 503, NULL,
3716 US"valid RCPT command must precede DATA");
3720 if (toomany && recipients_max_reject)
3722 sender_address = NULL; /* This will allow a new MAIL without RSET */
3723 sender_address_unrewritten = NULL;
3724 smtp_printf("554 Too many recipients\r\n");
3728 /* If there is an ACL, re-check the synchronization afterwards, since the
3729 ACL may have delayed. */
3731 if (acl_smtp_predata == NULL) rc = OK; else
3733 enable_dollar_recipients = TRUE;
3734 rc = acl_check(ACL_WHERE_PREDATA, NULL, acl_smtp_predata, &user_msg,
3736 enable_dollar_recipients = FALSE;
3737 if (rc == OK && !check_sync()) goto SYNC_FAILURE;
3742 if (user_msg == NULL)
3743 smtp_printf("354 Enter message, ending with \".\" on a line by itself\r\n");
3744 else smtp_user_msg(US"354", user_msg);
3746 message_ended = END_NOTENDED; /* Indicate in middle of data */
3749 /* Either the ACL failed the address, or it was deferred. */
3752 done = smtp_handle_acl_fail(ACL_WHERE_PREDATA, rc, user_msg, log_msg);
3758 rc = acl_check(ACL_WHERE_VRFY, NULL, acl_smtp_vrfy, &user_msg, &log_msg);
3760 done = smtp_handle_acl_fail(ACL_WHERE_VRFY, rc, user_msg, log_msg);
3766 /* rfc821_domains = TRUE; << no longer needed */
3767 address = parse_extract_address(smtp_cmd_data, &errmess, &start, &end,
3768 &recipient_domain, FALSE);
3769 /* rfc821_domains = FALSE; << no longer needed */
3771 if (address == NULL)
3772 s = string_sprintf("501 %s", errmess);
3775 address_item *addr = deliver_make_addr(address, FALSE);
3776 switch(verify_address(addr, NULL, vopt_is_recipient | vopt_qualify, -1,
3777 -1, -1, NULL, NULL, NULL))
3780 s = string_sprintf("250 <%s> is deliverable", address);
3784 s = (addr->user_message != NULL)?
3785 string_sprintf("451 <%s> %s", address, addr->user_message) :
3786 string_sprintf("451 Cannot resolve <%s> at this time", address);
3790 s = (addr->user_message != NULL)?
3791 string_sprintf("550 <%s> %s", address, addr->user_message) :
3792 string_sprintf("550 <%s> is not deliverable", address);
3793 log_write(0, LOG_MAIN, "VRFY failed for %s %s",
3794 smtp_cmd_argument, host_and_ident(TRUE));
3799 smtp_printf("%s\r\n", s);
3806 rc = acl_check(ACL_WHERE_EXPN, NULL, acl_smtp_expn, &user_msg, &log_msg);
3808 done = smtp_handle_acl_fail(ACL_WHERE_EXPN, rc, user_msg, log_msg);
3811 BOOL save_log_testing_mode = log_testing_mode;
3812 address_test_mode = log_testing_mode = TRUE;
3813 (void) verify_address(deliver_make_addr(smtp_cmd_data, FALSE),
3814 smtp_out, vopt_is_recipient | vopt_qualify | vopt_expn, -1, -1, -1,
3816 address_test_mode = FALSE;
3817 log_testing_mode = save_log_testing_mode; /* true for -bh */
3826 if (!tls_advertised)
3828 done = synprot_error(L_smtp_protocol_error, 503, NULL,
3829 US"STARTTLS command used when not advertised");
3833 /* Apply an ACL check if one is defined */
3835 if (acl_smtp_starttls != NULL)
3837 rc = acl_check(ACL_WHERE_STARTTLS, NULL, acl_smtp_starttls, &user_msg,
3841 done = smtp_handle_acl_fail(ACL_WHERE_STARTTLS, rc, user_msg, log_msg);
3846 /* RFC 2487 is not clear on when this command may be sent, though it
3847 does state that all information previously obtained from the client
3848 must be discarded if a TLS session is started. It seems reasonble to
3849 do an implied RSET when STARTTLS is received. */
3851 incomplete_transaction_log(US"STARTTLS");
3852 smtp_reset(reset_point);
3854 cmd_list[CMD_LIST_STARTTLS].is_mail_cmd = FALSE;
3856 /* There's an attack where more data is read in past the STARTTLS command
3857 before TLS is negotiated, then assumed to be part of the secure session
3858 when used afterwards; we use segregated input buffers, so are not
3859 vulnerable, but we want to note when it happens and, for sheer paranoia,
3860 ensure that the buffer is "wiped".
3861 Pipelining sync checks will normally have protected us too, unless disabled
3862 by configuration. */
3864 if (receive_smtp_buffered())
3867 debug_printf("Non-empty input buffer after STARTTLS; naive attack?");
3869 smtp_inend = smtp_inptr = smtp_inbuffer;
3870 /* and if TLS is already active, tls_server_start() should fail */
3873 /* There is nothing we value in the input buffer and if TLS is succesfully
3874 negotiated, we won't use this buffer again; if TLS fails, we'll just read
3875 fresh content into it. The buffer contains arbitrary content from an
3876 untrusted remote source; eg: NOOP <shellcode>\r\nSTARTTLS\r\n
3877 It seems safest to just wipe away the content rather than leave it as a
3878 target to jump to. */
3880 memset(smtp_inbuffer, 0, in_buffer_size);
3882 /* Attempt to start up a TLS session, and if successful, discard all
3883 knowledge that was obtained previously. At least, that's what the RFC says,
3884 and that's what happens by default. However, in order to work round YAEB,
3885 there is an option to remember the esmtp state. Sigh.
3887 We must allow for an extra EHLO command and an extra AUTH command after
3888 STARTTLS that don't add to the nonmail command count. */
3890 if ((rc = tls_server_start(tls_require_ciphers, gnutls_require_mac,
3891 gnutls_require_kx, gnutls_require_proto)) == OK)
3893 if (!tls_remember_esmtp)
3894 helo_seen = esmtp = auth_advertised = pipelining_advertised = FALSE;
3895 cmd_list[CMD_LIST_EHLO].is_mail_cmd = TRUE;
3896 cmd_list[CMD_LIST_AUTH].is_mail_cmd = TRUE;
3897 if (sender_helo_name != NULL)
3899 store_free(sender_helo_name);
3900 sender_helo_name = NULL;
3901 host_build_sender_fullhost(); /* Rebuild */
3902 set_process_info("handling incoming TLS connection from %s",
3903 host_and_ident(FALSE));
3905 received_protocol = (esmtp?
3906 protocols[pextend + pcrpted +
3907 ((sender_host_authenticated != NULL)? pauthed : 0)]
3909 protocols[pnormal + pcrpted])
3911 ((sender_host_address != NULL)? pnlocal : 0);
3913 sender_host_authenticated = NULL;
3914 authenticated_id = NULL;
3915 sync_cmd_limit = NON_SYNC_CMD_NON_PIPELINING;
3916 DEBUG(D_tls) debug_printf("TLS active\n");
3917 break; /* Successful STARTTLS */
3920 /* Some local configuration problem was discovered before actually trying
3921 to do a TLS handshake; give a temporary error. */
3923 else if (rc == DEFER)
3925 smtp_printf("454 TLS currently unavailable\r\n");
3929 /* Hard failure. Reject everything except QUIT or closed connection. One
3930 cause for failure is a nested STARTTLS, in which case tls_active remains
3931 set, but we must still reject all incoming commands. */
3933 DEBUG(D_tls) debug_printf("TLS failed to start\n");
3936 switch(smtp_read_command(FALSE))
3939 log_write(L_smtp_connection, LOG_MAIN, "%s closed by EOF",
3940 smtp_get_connection_info());
3941 smtp_notquit_exit(US"tls-failed", NULL, NULL);
3945 /* It is perhaps arguable as to which exit ACL should be called here,
3946 but as it is probably a situtation that almost never arises, it
3947 probably doesn't matter. We choose to call the real QUIT ACL, which in
3948 some sense is perhaps "right". */
3952 if (acl_smtp_quit != NULL)
3954 rc = acl_check(ACL_WHERE_QUIT, NULL, acl_smtp_quit, &user_msg,
3957 log_write(0, LOG_MAIN|LOG_PANIC, "ACL for QUIT returned ERROR: %s",
3960 if (user_msg == NULL)
3961 smtp_printf("221 %s closing connection\r\n", smtp_active_hostname);
3963 smtp_respond(US"221", 3, TRUE, user_msg);
3964 log_write(L_smtp_connection, LOG_MAIN, "%s closed by QUIT",
3965 smtp_get_connection_info());
3970 smtp_printf("554 Security failure\r\n");
3979 /* The ACL for QUIT is provided for gathering statistical information or
3980 similar; it does not affect the response code, but it can supply a custom
3985 incomplete_transaction_log(US"QUIT");
3986 if (acl_smtp_quit != NULL)
3988 rc = acl_check(ACL_WHERE_QUIT, NULL, acl_smtp_quit, &user_msg, &log_msg);
3990 log_write(0, LOG_MAIN|LOG_PANIC, "ACL for QUIT returned ERROR: %s",
3993 if (user_msg == NULL)
3994 smtp_printf("221 %s closing connection\r\n", smtp_active_hostname);
3996 smtp_respond(US"221", 3, TRUE, user_msg);
4003 log_write(L_smtp_connection, LOG_MAIN, "%s closed by QUIT",
4004 smtp_get_connection_info());
4010 incomplete_transaction_log(US"RSET");
4011 smtp_reset(reset_point);
4013 smtp_printf("250 Reset OK\r\n");
4014 cmd_list[CMD_LIST_RSET].is_mail_cmd = FALSE;
4020 smtp_printf("250 OK\r\n");
4024 /* Show ETRN/EXPN/VRFY if there's an ACL for checking hosts; if actually
4025 used, a check will be done for permitted hosts. Show STARTTLS only if not
4026 already in a TLS session and if it would be advertised in the EHLO
4031 smtp_printf("214-Commands supported:\r\n");
4035 Ustrcat(buffer, " AUTH");
4037 if (tls_active < 0 &&
4038 verify_check_host(&tls_advertise_hosts) != FAIL)
4039 Ustrcat(buffer, " STARTTLS");
4041 Ustrcat(buffer, " HELO EHLO MAIL RCPT DATA");
4042 Ustrcat(buffer, " NOOP QUIT RSET HELP");
4043 if (acl_smtp_etrn != NULL) Ustrcat(buffer, " ETRN");
4044 if (acl_smtp_expn != NULL) Ustrcat(buffer, " EXPN");
4045 if (acl_smtp_vrfy != NULL) Ustrcat(buffer, " VRFY");
4046 smtp_printf("214%s\r\n", buffer);
4052 incomplete_transaction_log(US"connection lost");
4053 smtp_notquit_exit(US"connection-lost", US"421",
4054 US"%s lost input connection", smtp_active_hostname);
4056 /* Don't log by default unless in the middle of a message, as some mailers
4057 just drop the call rather than sending QUIT, and it clutters up the logs.
4060 if (sender_address != NULL || recipients_count > 0)
4061 log_write(L_lost_incoming_connection,
4063 "unexpected %s while reading SMTP command from %s%s",
4064 sender_host_unknown? "EOF" : "disconnection",
4065 host_and_ident(FALSE), smtp_read_error);
4067 else log_write(L_smtp_connection, LOG_MAIN, "%s lost%s",
4068 smtp_get_connection_info(), smtp_read_error);
4076 if (sender_address != NULL)
4078 done = synprot_error(L_smtp_protocol_error, 503, NULL,
4079 US"ETRN is not permitted inside a transaction");
4083 log_write(L_etrn, LOG_MAIN, "ETRN %s received from %s", smtp_cmd_argument,
4084 host_and_ident(FALSE));
4086 rc = acl_check(ACL_WHERE_ETRN, NULL, acl_smtp_etrn, &user_msg, &log_msg);
4089 done = smtp_handle_acl_fail(ACL_WHERE_ETRN, rc, user_msg, log_msg);
4093 /* Compute the serialization key for this command. */
4095 etrn_serialize_key = string_sprintf("etrn-%s\n", smtp_cmd_data);
4097 /* If a command has been specified for running as a result of ETRN, we
4098 permit any argument to ETRN. If not, only the # standard form is permitted,
4099 since that is strictly the only kind of ETRN that can be implemented
4100 according to the RFC. */
4102 if (smtp_etrn_command != NULL)
4106 etrn_command = smtp_etrn_command;
4107 deliver_domain = smtp_cmd_data;
4108 rc = transport_set_up_command(&argv, smtp_etrn_command, TRUE, 0, NULL,
4109 US"ETRN processing", &error);
4110 deliver_domain = NULL;
4113 log_write(0, LOG_MAIN|LOG_PANIC, "failed to set up ETRN command: %s",
4115 smtp_printf("458 Internal failure\r\n");
4120 /* Else set up to call Exim with the -R option. */
4124 if (*smtp_cmd_data++ != '#')
4126 done = synprot_error(L_smtp_syntax_error, 501, NULL,
4127 US"argument must begin with #");
4130 etrn_command = US"exim -R";
4131 argv = child_exec_exim(CEE_RETURN_ARGV, TRUE, NULL, TRUE, 2, US"-R",
4135 /* If we are host-testing, don't actually do anything. */
4141 debug_printf("ETRN command is: %s\n", etrn_command);
4142 debug_printf("ETRN command execution skipped\n");
4144 if (user_msg == NULL) smtp_printf("250 OK\r\n");
4145 else smtp_user_msg(US"250", user_msg);
4150 /* If ETRN queue runs are to be serialized, check the database to
4151 ensure one isn't already running. */
4153 if (smtp_etrn_serialize && !enq_start(etrn_serialize_key))
4155 smtp_printf("458 Already processing %s\r\n", smtp_cmd_data);
4159 /* Fork a child process and run the command. We don't want to have to
4160 wait for the process at any point, so set SIGCHLD to SIG_IGN before
4161 forking. It should be set that way anyway for external incoming SMTP,
4162 but we save and restore to be tidy. If serialization is required, we
4163 actually run the command in yet another process, so we can wait for it
4164 to complete and then remove the serialization lock. */
4166 oldsignal = signal(SIGCHLD, SIG_IGN);
4168 if ((pid = fork()) == 0)
4170 smtp_input = FALSE; /* This process is not associated with the */
4171 (void)fclose(smtp_in); /* SMTP call any more. */
4172 (void)fclose(smtp_out);
4174 signal(SIGCHLD, SIG_DFL); /* Want to catch child */
4176 /* If not serializing, do the exec right away. Otherwise, fork down
4177 into another process. */
4179 if (!smtp_etrn_serialize || (pid = fork()) == 0)
4181 DEBUG(D_exec) debug_print_argv(argv);
4182 exim_nullstd(); /* Ensure std{in,out,err} exist */
4183 execv(CS argv[0], (char *const *)argv);
4184 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "exec of \"%s\" (ETRN) failed: %s",
4185 etrn_command, strerror(errno));
4186 _exit(EXIT_FAILURE); /* paranoia */
4189 /* Obey this if smtp_serialize and the 2nd fork yielded non-zero. That
4190 is, we are in the first subprocess, after forking again. All we can do
4191 for a failing fork is to log it. Otherwise, wait for the 2nd process to
4192 complete, before removing the serialization. */
4195 log_write(0, LOG_MAIN|LOG_PANIC, "2nd fork for serialized ETRN "
4196 "failed: %s", strerror(errno));
4200 DEBUG(D_any) debug_printf("waiting for serialized ETRN process %d\n",
4202 (void)wait(&status);
4203 DEBUG(D_any) debug_printf("serialized ETRN process %d ended\n",
4207 enq_end(etrn_serialize_key);
4208 _exit(EXIT_SUCCESS);
4211 /* Back in the top level SMTP process. Check that we started a subprocess
4212 and restore the signal state. */
4216 log_write(0, LOG_MAIN|LOG_PANIC, "fork of process for ETRN failed: %s",
4218 smtp_printf("458 Unable to fork process\r\n");
4219 if (smtp_etrn_serialize) enq_end(etrn_serialize_key);
4223 if (user_msg == NULL) smtp_printf("250 OK\r\n");
4224 else smtp_user_msg(US"250", user_msg);
4227 signal(SIGCHLD, oldsignal);
4232 done = synprot_error(L_smtp_syntax_error, 501, NULL,
4233 US"unexpected argument data");
4237 /* This currently happens only for NULLs, but could be extended. */
4240 done = synprot_error(L_smtp_syntax_error, 0, NULL, /* Just logs */
4241 US"NULL character(s) present (shown as '?')");
4242 smtp_printf("501 NULL characters are not allowed in SMTP commands\r\n");
4248 if (smtp_inend >= smtp_inbuffer + in_buffer_size)
4249 smtp_inend = smtp_inbuffer + in_buffer_size - 1;
4250 c = smtp_inend - smtp_inptr;
4251 if (c > 150) c = 150;
4253 incomplete_transaction_log(US"sync failure");
4254 log_write(0, LOG_MAIN|LOG_REJECT, "SMTP protocol synchronization error "
4255 "(next input sent too soon: pipelining was%s advertised): "
4256 "rejected \"%s\" %s next input=\"%s\"",
4257 pipelining_advertised? "" : " not",
4258 smtp_cmd_buffer, host_and_ident(TRUE),
4259 string_printing(smtp_inptr));
4260 smtp_notquit_exit(US"synchronization-error", US"554",
4261 US"SMTP synchronization error");
4262 done = 1; /* Pretend eof - drops connection */
4266 case TOO_MANY_NONMAIL_CMD:
4267 s = smtp_cmd_buffer;
4268 while (*s != 0 && !isspace(*s)) s++;
4269 incomplete_transaction_log(US"too many non-mail commands");
4270 log_write(0, LOG_MAIN|LOG_REJECT, "SMTP call from %s dropped: too many "
4271 "nonmail commands (last was \"%.*s\")", host_and_ident(FALSE),
4272 s - smtp_cmd_buffer, smtp_cmd_buffer);
4273 smtp_notquit_exit(US"bad-commands", US"554", US"Too many nonmail commands");
4274 done = 1; /* Pretend eof - drops connection */
4279 if (unknown_command_count++ >= smtp_max_unknown_commands)
4281 log_write(L_smtp_syntax_error, LOG_MAIN,
4282 "SMTP syntax error in \"%s\" %s %s",
4283 string_printing(smtp_cmd_buffer), host_and_ident(TRUE),
4284 US"unrecognized command");
4285 incomplete_transaction_log(US"unrecognized command");
4286 smtp_notquit_exit(US"bad-commands", US"500",
4287 US"Too many unrecognized commands");
4289 log_write(0, LOG_MAIN|LOG_REJECT, "SMTP call from %s dropped: too many "
4290 "unrecognized commands (last was \"%s\")", host_and_ident(FALSE),
4294 done = synprot_error(L_smtp_syntax_error, 500, NULL,
4295 US"unrecognized command");
4299 /* This label is used by goto's inside loops that want to break out to
4300 the end of the command-processing loop. */
4303 last_was_rej_mail = was_rej_mail; /* Remember some last commands for */
4304 last_was_rcpt = was_rcpt; /* protocol error handling */
4308 return done - 2; /* Convert yield values */
4311 /* End of smtp_in.c */