1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
5 /* Copyright (c) University of Cambridge 1995 - 2012 */
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 /* Sanity check and validate optional args to MAIL FROM: envelope */
212 ENV_MAIL_OPT_SIZE, ENV_MAIL_OPT_BODY, ENV_MAIL_OPT_AUTH,
213 #ifdef EXPERIMENTAL_PRDR
219 uschar * name; /* option requested during MAIL cmd */
220 int value; /* enum type */
221 BOOL need_value; /* TRUE requires value (name=value pair format)
222 FALSE is a singleton */
224 static env_mail_type_t env_mail_type_list[] = {
225 { US"SIZE", ENV_MAIL_OPT_SIZE, TRUE },
226 { US"BODY", ENV_MAIL_OPT_BODY, TRUE },
227 { US"AUTH", ENV_MAIL_OPT_AUTH, TRUE },
228 #ifdef EXPERIMENTAL_PRDR
229 { US"PRDR", ENV_MAIL_OPT_PRDR, FALSE },
231 { US"NULL", ENV_MAIL_OPT_NULL, FALSE }
234 /* When reading SMTP from a remote host, we have to use our own versions of the
235 C input-reading functions, in order to be able to flush the SMTP output only
236 when about to read more data from the socket. This is the only way to get
237 optimal performance when the client is using pipelining. Flushing for every
238 command causes a separate packet and reply packet each time; saving all the
239 responses up (when pipelining) combines them into one packet and one response.
241 For simplicity, these functions are used for *all* SMTP input, not only when
242 receiving over a socket. However, after setting up a secure socket (SSL), input
243 is read via the OpenSSL library, and another set of functions is used instead
246 These functions are set in the receive_getc etc. variables and called with the
247 same interface as the C functions. However, since there can only ever be
248 one incoming SMTP call, we just use a single buffer and flags. There is no need
249 to implement a complicated private FILE-like structure.*/
251 static uschar *smtp_inbuffer;
252 static uschar *smtp_inptr;
253 static uschar *smtp_inend;
254 static int smtp_had_eof;
255 static int smtp_had_error;
258 /*************************************************
259 * SMTP version of getc() *
260 *************************************************/
262 /* This gets the next byte from the SMTP input buffer. If the buffer is empty,
263 it flushes the output, and refills the buffer, with a timeout. The signal
264 handler is set appropriately by the calling function. This function is not used
265 after a connection has negotated itself into an TLS/SSL state.
268 Returns: the next character or EOF
274 if (smtp_inptr >= smtp_inend)
278 if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
279 rc = read(fileno(smtp_in), smtp_inbuffer, in_buffer_size);
284 /* Must put the error text in fixed store, because this might be during
285 header reading, where it releases unused store above the header. */
288 smtp_had_error = save_errno;
289 smtp_read_error = string_copy_malloc(
290 string_sprintf(" (error: %s)", strerror(save_errno)));
292 else smtp_had_eof = 1;
296 dkim_exim_verify_feed(smtp_inbuffer, rc);
298 smtp_inend = smtp_inbuffer + rc;
299 smtp_inptr = smtp_inbuffer;
301 return *smtp_inptr++;
306 /*************************************************
307 * SMTP version of ungetc() *
308 *************************************************/
310 /* Puts a character back in the input buffer. Only ever
316 Returns: the character
322 *(--smtp_inptr) = ch;
329 /*************************************************
330 * SMTP version of feof() *
331 *************************************************/
333 /* Tests for a previous EOF
336 Returns: non-zero if the eof flag is set
348 /*************************************************
349 * SMTP version of ferror() *
350 *************************************************/
352 /* Tests for a previous read error, and returns with errno
353 restored to what it was when the error was detected.
356 Returns: non-zero if the error flag is set
362 errno = smtp_had_error;
363 return smtp_had_error;
368 /*************************************************
369 * Test for characters in the SMTP buffer *
370 *************************************************/
372 /* Used at the end of a message
381 return smtp_inptr < smtp_inend;
386 /*************************************************
387 * Write formatted string to SMTP channel *
388 *************************************************/
390 /* This is a separate function so that we don't have to repeat everything for
391 TLS support or debugging. It is global so that the daemon and the
392 authentication functions can use it. It does not return any error indication,
393 because major problems such as dropped connections won't show up till an output
394 flush for non-TLS connections. The smtp_fflush() function is available for
395 checking that: for convenience, TLS output errors are remembered here so that
396 they are also picked up later by smtp_fflush().
400 ... optional arguments
406 smtp_printf(const char *format, ...)
410 va_start(ap, format);
411 smtp_vprintf(format, ap);
415 /* This is split off so that verify.c:respond_printf() can, in effect, call
416 smtp_printf(), bearing in mind that in C a vararg function can't directly
417 call another vararg function, only a function which accepts a va_list. */
420 smtp_vprintf(const char *format, va_list ap)
424 yield = string_vformat(big_buffer, big_buffer_size, format, ap);
428 void *reset_point = store_get(0);
429 uschar *msg_copy, *cr, *end;
430 msg_copy = string_copy(big_buffer);
431 end = msg_copy + Ustrlen(msg_copy);
432 while ((cr = Ustrchr(msg_copy, '\r')) != NULL) /* lose CRs */
433 memmove(cr, cr + 1, (end--) - cr);
434 debug_printf("SMTP>> %s", msg_copy);
435 store_reset(reset_point);
440 log_write(0, LOG_MAIN|LOG_PANIC, "string too large in smtp_printf()");
441 smtp_closedown(US"Unexpected error");
442 exim_exit(EXIT_FAILURE);
445 /* If this is the first output for a (non-batch) RCPT command, see if all RCPTs
446 have had the same. Note: this code is also present in smtp_respond(). It would
447 be tidier to have it only in one place, but when it was added, it was easier to
448 do it that way, so as not to have to mess with the code for the RCPT command,
449 which sometimes uses smtp_printf() and sometimes smtp_respond(). */
451 if (rcpt_in_progress)
453 if (rcpt_smtp_response == NULL)
454 rcpt_smtp_response = string_copy(big_buffer);
455 else if (rcpt_smtp_response_same &&
456 Ustrcmp(rcpt_smtp_response, big_buffer) != 0)
457 rcpt_smtp_response_same = FALSE;
458 rcpt_in_progress = FALSE;
461 /* Now write the string */
464 if (tls_in.active >= 0)
466 if (tls_write(TRUE, big_buffer, Ustrlen(big_buffer)) < 0)
467 smtp_write_error = -1;
472 if (fprintf(smtp_out, "%s", big_buffer) < 0) smtp_write_error = -1;
477 /*************************************************
478 * Flush SMTP out and check for error *
479 *************************************************/
481 /* This function isn't currently used within Exim (it detects errors when it
482 tries to read the next SMTP input), but is available for use in local_scan().
483 For non-TLS connections, it flushes the output and checks for errors. For
484 TLS-connections, it checks for a previously-detected TLS write error.
487 Returns: 0 for no error; -1 after an error
493 if (tls_in.active < 0 && fflush(smtp_out) != 0) smtp_write_error = -1;
494 return smtp_write_error;
499 /*************************************************
500 * SMTP command read timeout *
501 *************************************************/
503 /* Signal handler for timing out incoming SMTP commands. This attempts to
506 Argument: signal number (SIGALRM)
511 command_timeout_handler(int sig)
513 sig = sig; /* Keep picky compilers happy */
514 log_write(L_lost_incoming_connection,
515 LOG_MAIN, "SMTP command timeout on%s connection from %s",
516 (tls_in.active >= 0)? " TLS" : "",
517 host_and_ident(FALSE));
518 if (smtp_batched_input)
519 moan_smtp_batch(NULL, "421 SMTP command timeout"); /* Does not return */
520 smtp_notquit_exit(US"command-timeout", US"421",
521 US"%s: SMTP command timeout - closing connection", smtp_active_hostname);
522 exim_exit(EXIT_FAILURE);
527 /*************************************************
529 *************************************************/
531 /* Signal handler for handling SIGTERM. Again, try to finish tidily.
533 Argument: signal number (SIGTERM)
538 command_sigterm_handler(int sig)
540 sig = sig; /* Keep picky compilers happy */
541 log_write(0, LOG_MAIN, "%s closed after SIGTERM", smtp_get_connection_info());
542 if (smtp_batched_input)
543 moan_smtp_batch(NULL, "421 SIGTERM received"); /* Does not return */
544 smtp_notquit_exit(US"signal-exit", US"421",
545 US"%s: Service not available - closing connection", smtp_active_hostname);
546 exim_exit(EXIT_FAILURE);
552 /*************************************************
553 * Read one command line *
554 *************************************************/
556 /* Strictly, SMTP commands coming over the net are supposed to end with CRLF.
557 There are sites that don't do this, and in any case internal SMTP probably
558 should check only for LF. Consequently, we check here for LF only. The line
559 ends up with [CR]LF removed from its end. If we get an overlong line, treat as
560 an unknown command. The command is read into the global smtp_cmd_buffer so that
561 it is available via $smtp_command.
563 The character reading routine sets up a timeout for each block actually read
564 from the input (which may contain more than one command). We set up a special
565 signal handler that closes down the session on a timeout. Control does not
569 check_sync if TRUE, check synchronization rules if global option is TRUE
571 Returns: a code identifying the command (enumerated above)
575 smtp_read_command(BOOL check_sync)
580 BOOL hadnull = FALSE;
582 os_non_restarting_signal(SIGALRM, command_timeout_handler);
584 while ((c = (receive_getc)()) != '\n' && c != EOF)
586 if (ptr >= smtp_cmd_buffer_size)
588 os_non_restarting_signal(SIGALRM, sigalrm_handler);
596 smtp_cmd_buffer[ptr++] = c;
599 receive_linecount++; /* For BSMTP errors */
600 os_non_restarting_signal(SIGALRM, sigalrm_handler);
602 /* If hit end of file, return pseudo EOF command. Whether we have a
603 part-line already read doesn't matter, since this is an error state. */
605 if (c == EOF) return EOF_CMD;
607 /* Remove any CR and white space at the end of the line, and terminate the
610 while (ptr > 0 && isspace(smtp_cmd_buffer[ptr-1])) ptr--;
611 smtp_cmd_buffer[ptr] = 0;
613 DEBUG(D_receive) debug_printf("SMTP<< %s\n", smtp_cmd_buffer);
615 /* NULLs are not allowed in SMTP commands */
617 if (hadnull) return BADCHAR_CMD;
619 /* Scan command list and return identity, having set the data pointer
620 to the start of the actual data characters. Check for SMTP synchronization
623 for (p = cmd_list; p < cmd_list_end; p++)
625 if (strncmpic(smtp_cmd_buffer, US p->name, p->len) == 0 &&
626 (smtp_cmd_buffer[p->len-1] == ':' || /* "mail from:" or "rcpt to:" */
627 smtp_cmd_buffer[p->len] == 0 ||
628 smtp_cmd_buffer[p->len] == ' '))
630 if (smtp_inptr < smtp_inend && /* Outstanding input */
631 p->cmd < sync_cmd_limit && /* Command should sync */
632 check_sync && /* Local flag set */
633 smtp_enforce_sync && /* Global flag set */
634 sender_host_address != NULL && /* Not local input */
635 !sender_host_notsocket) /* Really is a socket */
638 /* The variables $smtp_command and $smtp_command_argument point into the
639 unmodified input buffer. A copy of the latter is taken for actual
640 processing, so that it can be chopped up into separate parts if necessary,
641 for example, when processing a MAIL command options such as SIZE that can
642 follow the sender address. */
644 smtp_cmd_argument = smtp_cmd_buffer + p->len;
645 while (isspace(*smtp_cmd_argument)) smtp_cmd_argument++;
646 Ustrcpy(smtp_data_buffer, smtp_cmd_argument);
647 smtp_cmd_data = smtp_data_buffer;
649 /* Count non-mail commands from those hosts that are controlled in this
650 way. The default is all hosts. We don't waste effort checking the list
651 until we get a non-mail command, but then cache the result to save checking
652 again. If there's a DEFER while checking the host, assume it's in the list.
654 Note that one instance of RSET, EHLO/HELO, and STARTTLS is allowed at the
655 start of each incoming message by fiddling with the value in the table. */
659 if (count_nonmail == TRUE_UNSET) count_nonmail =
660 verify_check_host(&smtp_accept_max_nonmail_hosts) != FAIL;
661 if (count_nonmail && ++nonmail_command_count > smtp_accept_max_nonmail)
662 return TOO_MANY_NONMAIL_CMD;
665 /* If there is data for a command that does not expect it, generate the
668 return (p->has_arg || *smtp_cmd_data == 0)? p->cmd : BADARG_CMD;
672 /* Enforce synchronization for unknown commands */
674 if (smtp_inptr < smtp_inend && /* Outstanding input */
675 check_sync && /* Local flag set */
676 smtp_enforce_sync && /* Global flag set */
677 sender_host_address != NULL && /* Not local input */
678 !sender_host_notsocket) /* Really is a socket */
686 /*************************************************
687 * Recheck synchronization *
688 *************************************************/
690 /* Synchronization checks can never be perfect because a packet may be on its
691 way but not arrived when the check is done. Such checks can in any case only be
692 done when TLS is not in use. Normally, the checks happen when commands are
693 read: Exim ensures that there is no more input in the input buffer. In normal
694 cases, the response to the command will be fast, and there is no further check.
696 However, for some commands an ACL is run, and that can include delays. In those
697 cases, it is useful to do another check on the input just before sending the
698 response. This also applies at the start of a connection. This function does
699 that check by means of the select() function, as long as the facility is not
700 disabled or inappropriate. A failure of select() is ignored.
702 When there is unwanted input, we read it so that it appears in the log of the
706 Returns: TRUE if all is well; FALSE if there is input pending
714 struct timeval tzero;
716 if (!smtp_enforce_sync || sender_host_address == NULL ||
717 sender_host_notsocket || tls_in.active >= 0)
720 fd = fileno(smtp_in);
725 rc = select(fd + 1, (SELECT_ARG2_TYPE *)&fds, NULL, NULL, &tzero);
727 if (rc <= 0) return TRUE; /* Not ready to read */
729 if (rc < 0) return TRUE; /* End of file or error */
732 rc = smtp_inend - smtp_inptr;
733 if (rc > 150) rc = 150;
740 /*************************************************
741 * Forced closedown of call *
742 *************************************************/
744 /* This function is called from log.c when Exim is dying because of a serious
745 disaster, and also from some other places. If an incoming non-batched SMTP
746 channel is open, it swallows the rest of the incoming message if in the DATA
747 phase, sends the reply string, and gives an error to all subsequent commands
748 except QUIT. The existence of an SMTP call is detected by the non-NULLness of
752 message SMTP reply string to send, excluding the code
758 smtp_closedown(uschar *message)
760 if (smtp_in == NULL || smtp_batched_input) return;
761 receive_swallow_smtp();
762 smtp_printf("421 %s\r\n", message);
766 switch(smtp_read_command(FALSE))
772 smtp_printf("221 %s closing connection\r\n", smtp_active_hostname);
777 smtp_printf("250 Reset OK\r\n");
781 smtp_printf("421 %s\r\n", message);
790 /*************************************************
791 * Set up connection info for logging *
792 *************************************************/
794 /* This function is called when logging information about an SMTP connection.
795 It sets up appropriate source information, depending on the type of connection.
796 If sender_fullhost is NULL, we are at a very early stage of the connection;
797 just use the IP address.
800 Returns: a string describing the connection
804 smtp_get_connection_info(void)
806 uschar *hostname = (sender_fullhost == NULL)?
807 sender_host_address : sender_fullhost;
810 return string_sprintf("SMTP connection from %s", hostname);
812 if (sender_host_unknown || sender_host_notsocket)
813 return string_sprintf("SMTP connection from %s", sender_ident);
816 return string_sprintf("SMTP connection from %s (via inetd)", hostname);
818 if ((log_extra_selector & LX_incoming_interface) != 0 &&
819 interface_address != NULL)
820 return string_sprintf("SMTP connection from %s I=[%s]:%d", hostname,
821 interface_address, interface_port);
823 return string_sprintf("SMTP connection from %s", hostname);
828 /*************************************************
829 * Log lack of MAIL if so configured *
830 *************************************************/
832 /* This function is called when an SMTP session ends. If the log selector
833 smtp_no_mail is set, write a log line giving some details of what has happened
841 smtp_log_no_mail(void)
846 if (smtp_mailcmd_count > 0 || (log_extra_selector & LX_smtp_no_mail) == 0)
852 if (sender_host_authenticated != NULL)
854 s = string_append(s, &size, &ptr, 2, US" A=", sender_host_authenticated);
855 if (authenticated_id != NULL)
856 s = string_append(s, &size, &ptr, 2, US":", authenticated_id);
860 if ((log_extra_selector & LX_tls_cipher) != 0 && tls_in.cipher != NULL)
861 s = string_append(s, &size, &ptr, 2, US" X=", tls_in.cipher);
862 if ((log_extra_selector & LX_tls_certificate_verified) != 0 &&
863 tls_in.cipher != NULL)
864 s = string_append(s, &size, &ptr, 2, US" CV=",
865 tls_in.certificate_verified? "yes":"no");
866 if ((log_extra_selector & LX_tls_peerdn) != 0 && tls_in.peerdn != NULL)
867 s = string_append(s, &size, &ptr, 3, US" DN=\"",
868 string_printing(tls_in.peerdn), US"\"");
869 if ((log_extra_selector & LX_tls_sni) != 0 && tls_in.sni != NULL)
870 s = string_append(s, &size, &ptr, 3, US" SNI=\"",
871 string_printing(tls_in.sni), US"\"");
874 sep = (smtp_connection_had[SMTP_HBUFF_SIZE-1] != SCH_NONE)?
875 US" C=..." : US" C=";
876 for (i = smtp_ch_index; i < SMTP_HBUFF_SIZE; i++)
878 if (smtp_connection_had[i] != SCH_NONE)
880 s = string_append(s, &size, &ptr, 2, sep,
881 smtp_names[smtp_connection_had[i]]);
886 for (i = 0; i < smtp_ch_index; i++)
888 s = string_append(s, &size, &ptr, 2, sep, smtp_names[smtp_connection_had[i]]);
892 if (s != NULL) s[ptr] = 0; else s = US"";
893 log_write(0, LOG_MAIN, "no MAIL in SMTP connection from %s D=%s%s",
894 host_and_ident(FALSE),
895 readconf_printtime(time(NULL) - smtp_connection_start), s);
900 /*************************************************
901 * Check HELO line and set sender_helo_name *
902 *************************************************/
904 /* Check the format of a HELO line. The data for HELO/EHLO is supposed to be
905 the domain name of the sending host, or an ip literal in square brackets. The
906 arrgument is placed in sender_helo_name, which is in malloc store, because it
907 must persist over multiple incoming messages. If helo_accept_junk is set, this
908 host is permitted to send any old junk (needed for some broken hosts).
909 Otherwise, helo_allow_chars can be used for rogue characters in general
910 (typically people want to let in underscores).
913 s the data portion of the line (already past any white space)
915 Returns: TRUE or FALSE
919 check_helo(uschar *s)
922 uschar *end = s + Ustrlen(s);
923 BOOL yield = helo_accept_junk;
925 /* Discard any previous helo name */
927 if (sender_helo_name != NULL)
929 store_free(sender_helo_name);
930 sender_helo_name = NULL;
933 /* Skip tests if junk is permitted. */
937 /* Allow the new standard form for IPv6 address literals, namely,
938 [IPv6:....], and because someone is bound to use it, allow an equivalent
939 IPv4 form. Allow plain addresses as well. */
946 if (strncmpic(s, US"[IPv6:", 6) == 0)
947 yield = (string_is_ip_address(s+6, NULL) == 6);
948 else if (strncmpic(s, US"[IPv4:", 6) == 0)
949 yield = (string_is_ip_address(s+6, NULL) == 4);
951 yield = (string_is_ip_address(s+1, NULL) != 0);
956 /* Non-literals must be alpha, dot, hyphen, plus any non-valid chars
957 that have been configured (usually underscore - sigh). */
964 if (!isalnum(*s) && *s != '.' && *s != '-' &&
965 Ustrchr(helo_allow_chars, *s) == NULL)
975 /* Save argument if OK */
977 if (yield) sender_helo_name = string_copy_malloc(start);
985 /*************************************************
986 * Extract SMTP command option *
987 *************************************************/
989 /* This function picks the next option setting off the end of smtp_cmd_data. It
990 is called for MAIL FROM and RCPT TO commands, to pick off the optional ESMTP
991 things that can appear there.
994 name point this at the name
995 value point this at the data string
997 Returns: TRUE if found an option
1001 extract_option(uschar **name, uschar **value)
1004 uschar *v = smtp_cmd_data + Ustrlen(smtp_cmd_data) - 1;
1005 while (isspace(*v)) v--;
1007 while (v > smtp_cmd_data && *v != '=' && !isspace(*v)) v--;
1012 while(isalpha(n[-1])) n--;
1013 /* RFC says SP, but TAB seen in wild and other major MTAs accept it */
1014 if (!isspace(n[-1])) return FALSE;
1020 if (v == smtp_cmd_data) return FALSE;
1032 /*************************************************
1033 * Reset for new message *
1034 *************************************************/
1036 /* This function is called whenever the SMTP session is reset from
1037 within either of the setup functions.
1039 Argument: the stacking pool storage reset point
1044 smtp_reset(void *reset_point)
1046 store_reset(reset_point);
1047 recipients_list = NULL;
1048 rcpt_count = rcpt_defer_count = rcpt_fail_count =
1049 raw_recipients_count = recipients_count = recipients_list_max = 0;
1050 cancel_cutthrough_connection("smtp reset");
1051 message_linecount = 0;
1053 acl_added_headers = NULL;
1054 acl_removed_headers = NULL;
1055 queue_only_policy = FALSE;
1056 rcpt_smtp_response = NULL;
1057 rcpt_smtp_response_same = TRUE;
1058 rcpt_in_progress = FALSE;
1059 deliver_freeze = FALSE; /* Can be set by ACL */
1060 freeze_tell = freeze_tell_config; /* Can be set by ACL */
1061 fake_response = OK; /* Can be set by ACL */
1062 #ifdef WITH_CONTENT_SCAN
1063 no_mbox_unspool = FALSE; /* Can be set by ACL */
1065 submission_mode = FALSE; /* Can be set by ACL */
1066 suppress_local_fixups = suppress_local_fixups_default; /* Can be set by ACL */
1067 active_local_from_check = local_from_check; /* Can be set by ACL */
1068 active_local_sender_retain = local_sender_retain; /* Can be set by ACL */
1069 sender_address = NULL;
1070 submission_name = NULL; /* Can be set by ACL */
1071 raw_sender = NULL; /* After SMTP rewrite, before qualifying */
1072 sender_address_unrewritten = NULL; /* Set only after verify rewrite */
1073 sender_verified_list = NULL; /* No senders verified */
1074 memset(sender_address_cache, 0, sizeof(sender_address_cache));
1075 memset(sender_domain_cache, 0, sizeof(sender_domain_cache));
1076 authenticated_sender = NULL;
1077 #ifdef EXPERIMENTAL_BRIGHTMAIL
1079 bmi_verdicts = NULL;
1081 #ifndef DISABLE_DKIM
1082 dkim_signers = NULL;
1083 dkim_disable_verify = FALSE;
1084 dkim_collect_input = FALSE;
1086 #ifdef EXPERIMENTAL_SPF
1087 spf_header_comment = NULL;
1088 spf_received = NULL;
1090 spf_smtp_comment = NULL;
1092 body_linecount = body_zerocount = 0;
1094 sender_rate = sender_rate_limit = sender_rate_period = NULL;
1095 ratelimiters_mail = NULL; /* Updated by ratelimit ACL condition */
1096 /* Note that ratelimiters_conn persists across resets. */
1098 /* Reset message ACL variables */
1102 /* The message body variables use malloc store. They may be set if this is
1103 not the first message in an SMTP session and the previous message caused them
1104 to be referenced in an ACL. */
1106 if (message_body != NULL)
1108 store_free(message_body);
1109 message_body = NULL;
1112 if (message_body_end != NULL)
1114 store_free(message_body_end);
1115 message_body_end = NULL;
1118 /* Warning log messages are also saved in malloc store. They are saved to avoid
1119 repetition in the same message, but it seems right to repeat them for different
1122 while (acl_warn_logged != NULL)
1124 string_item *this = acl_warn_logged;
1125 acl_warn_logged = acl_warn_logged->next;
1134 /*************************************************
1135 * Initialize for incoming batched SMTP message *
1136 *************************************************/
1138 /* This function is called from smtp_setup_msg() in the case when
1139 smtp_batched_input is true. This happens when -bS is used to pass a whole batch
1140 of messages in one file with SMTP commands between them. All errors must be
1141 reported by sending a message, and only MAIL FROM, RCPT TO, and DATA are
1142 relevant. After an error on a sender, or an invalid recipient, the remainder
1143 of the message is skipped. The value of received_protocol is already set.
1146 Returns: > 0 message successfully started (reached DATA)
1147 = 0 QUIT read or end of file reached
1148 < 0 should not occur
1152 smtp_setup_batch_msg(void)
1155 void *reset_point = store_get(0);
1157 /* Save the line count at the start of each transaction - single commands
1158 like HELO and RSET count as whole transactions. */
1160 bsmtp_transaction_linecount = receive_linecount;
1162 if ((receive_feof)()) return 0; /* Treat EOF as QUIT */
1164 smtp_reset(reset_point); /* Reset for start of message */
1166 /* Deal with SMTP commands. This loop is exited by setting done to a POSITIVE
1167 value. The values are 2 larger than the required yield of the function. */
1172 uschar *recipient = NULL;
1173 int start, end, sender_domain, recipient_domain;
1175 switch(smtp_read_command(FALSE))
1177 /* The HELO/EHLO commands set sender_address_helo if they have
1178 valid data; otherwise they are ignored, except that they do
1179 a reset of the state. */
1184 check_helo(smtp_cmd_data);
1188 smtp_reset(reset_point);
1189 bsmtp_transaction_linecount = receive_linecount;
1193 /* The MAIL FROM command requires an address as an operand. All we
1194 do here is to parse it for syntactic correctness. The form "<>" is
1195 a special case which converts into an empty string. The start/end
1196 pointers in the original are not used further for this address, as
1197 it is the canonical extracted address which is all that is kept. */
1200 if (sender_address != NULL)
1201 /* The function moan_smtp_batch() does not return. */
1202 moan_smtp_batch(smtp_cmd_buffer, "503 Sender already given");
1204 if (smtp_cmd_data[0] == 0)
1205 /* The function moan_smtp_batch() does not return. */
1206 moan_smtp_batch(smtp_cmd_buffer, "501 MAIL FROM must have an address operand");
1208 /* Reset to start of message */
1210 smtp_reset(reset_point);
1212 /* Apply SMTP rewrite */
1214 raw_sender = ((rewrite_existflags & rewrite_smtp) != 0)?
1215 rewrite_one(smtp_cmd_data, rewrite_smtp|rewrite_smtp_sender, NULL, FALSE,
1216 US"", global_rewrite_rules) : smtp_cmd_data;
1218 /* Extract the address; the TRUE flag allows <> as valid */
1221 parse_extract_address(raw_sender, &errmess, &start, &end, &sender_domain,
1224 if (raw_sender == NULL)
1225 /* The function moan_smtp_batch() does not return. */
1226 moan_smtp_batch(smtp_cmd_buffer, "501 %s", errmess);
1228 sender_address = string_copy(raw_sender);
1230 /* Qualify unqualified sender addresses if permitted to do so. */
1232 if (sender_domain == 0 && sender_address[0] != 0 && sender_address[0] != '@')
1234 if (allow_unqualified_sender)
1236 sender_address = rewrite_address_qualify(sender_address, FALSE);
1237 DEBUG(D_receive) debug_printf("unqualified address %s accepted "
1238 "and rewritten\n", raw_sender);
1240 /* The function moan_smtp_batch() does not return. */
1241 else moan_smtp_batch(smtp_cmd_buffer, "501 sender address must contain "
1247 /* The RCPT TO command requires an address as an operand. All we do
1248 here is to parse it for syntactic correctness. There may be any number
1249 of RCPT TO commands, specifying multiple senders. We build them all into
1250 a data structure that is in argc/argv format. The start/end values
1251 given by parse_extract_address are not used, as we keep only the
1252 extracted address. */
1255 if (sender_address == NULL)
1256 /* The function moan_smtp_batch() does not return. */
1257 moan_smtp_batch(smtp_cmd_buffer, "503 No sender yet given");
1259 if (smtp_cmd_data[0] == 0)
1260 /* The function moan_smtp_batch() does not return. */
1261 moan_smtp_batch(smtp_cmd_buffer, "501 RCPT TO must have an address operand");
1263 /* Check maximum number allowed */
1265 if (recipients_max > 0 && recipients_count + 1 > recipients_max)
1266 /* The function moan_smtp_batch() does not return. */
1267 moan_smtp_batch(smtp_cmd_buffer, "%s too many recipients",
1268 recipients_max_reject? "552": "452");
1270 /* Apply SMTP rewrite, then extract address. Don't allow "<>" as a
1271 recipient address */
1273 recipient = ((rewrite_existflags & rewrite_smtp) != 0)?
1274 rewrite_one(smtp_cmd_data, rewrite_smtp, NULL, FALSE, US"",
1275 global_rewrite_rules) : smtp_cmd_data;
1277 /* rfc821_domains = TRUE; << no longer needed */
1278 recipient = parse_extract_address(recipient, &errmess, &start, &end,
1279 &recipient_domain, FALSE);
1280 /* rfc821_domains = FALSE; << no longer needed */
1282 if (recipient == NULL)
1283 /* The function moan_smtp_batch() does not return. */
1284 moan_smtp_batch(smtp_cmd_buffer, "501 %s", errmess);
1286 /* If the recipient address is unqualified, qualify it if permitted. Then
1287 add it to the list of recipients. */
1289 if (recipient_domain == 0)
1291 if (allow_unqualified_recipient)
1293 DEBUG(D_receive) debug_printf("unqualified address %s accepted\n",
1295 recipient = rewrite_address_qualify(recipient, TRUE);
1297 /* The function moan_smtp_batch() does not return. */
1298 else moan_smtp_batch(smtp_cmd_buffer, "501 recipient address must contain "
1301 receive_add_recipient(recipient, -1);
1305 /* The DATA command is legal only if it follows successful MAIL FROM
1306 and RCPT TO commands. This function is complete when a valid DATA
1307 command is encountered. */
1310 if (sender_address == NULL || recipients_count <= 0)
1312 /* The function moan_smtp_batch() does not return. */
1313 if (sender_address == NULL)
1314 moan_smtp_batch(smtp_cmd_buffer,
1315 "503 MAIL FROM:<sender> command must precede DATA");
1317 moan_smtp_batch(smtp_cmd_buffer,
1318 "503 RCPT TO:<recipient> must precede DATA");
1322 done = 3; /* DATA successfully achieved */
1323 message_ended = END_NOTENDED; /* Indicate in middle of message */
1328 /* The VRFY, EXPN, HELP, ETRN, and NOOP commands are ignored. */
1335 bsmtp_transaction_linecount = receive_linecount;
1346 /* The function moan_smtp_batch() does not return. */
1347 moan_smtp_batch(smtp_cmd_buffer, "501 Unexpected argument data");
1352 /* The function moan_smtp_batch() does not return. */
1353 moan_smtp_batch(smtp_cmd_buffer, "501 Unexpected NULL in SMTP command");
1358 /* The function moan_smtp_batch() does not return. */
1359 moan_smtp_batch(smtp_cmd_buffer, "500 Command unrecognized");
1364 return done - 2; /* Convert yield values */
1370 /*************************************************
1371 * Start an SMTP session *
1372 *************************************************/
1374 /* This function is called at the start of an SMTP session. Thereafter,
1375 smtp_setup_msg() is called to initiate each separate message. This
1376 function does host-specific testing, and outputs the banner line.
1379 Returns: FALSE if the session can not continue; something has
1380 gone wrong, or the connection to the host is blocked
1384 smtp_start_session(void)
1388 uschar *user_msg, *log_msg;
1392 smtp_connection_start = time(NULL);
1393 for (smtp_ch_index = 0; smtp_ch_index < SMTP_HBUFF_SIZE; smtp_ch_index++)
1394 smtp_connection_had[smtp_ch_index] = SCH_NONE;
1397 /* Default values for certain variables */
1399 helo_seen = esmtp = helo_accept_junk = FALSE;
1400 smtp_mailcmd_count = 0;
1401 count_nonmail = TRUE_UNSET;
1402 synprot_error_count = unknown_command_count = nonmail_command_count = 0;
1403 smtp_delay_mail = smtp_rlm_base;
1404 auth_advertised = FALSE;
1405 pipelining_advertised = FALSE;
1406 pipelining_enable = TRUE;
1407 sync_cmd_limit = NON_SYNC_CMD_NON_PIPELINING;
1408 smtp_exit_function_called = FALSE; /* For avoiding loop in not-quit exit */
1410 memset(sender_host_cache, 0, sizeof(sender_host_cache));
1412 /* If receiving by -bs from a trusted user, or testing with -bh, we allow
1413 authentication settings from -oMaa to remain in force. */
1415 if (!host_checking && !sender_host_notsocket) sender_host_authenticated = NULL;
1416 authenticated_by = NULL;
1419 tls_in.cipher = tls_in.peerdn = NULL;
1420 tls_advertised = FALSE;
1423 /* Reset ACL connection variables */
1427 /* Allow for trailing 0 in the command and data buffers. */
1429 smtp_cmd_buffer = (uschar *)malloc(2*smtp_cmd_buffer_size + 2);
1430 if (smtp_cmd_buffer == NULL)
1431 log_write(0, LOG_MAIN|LOG_PANIC_DIE,
1432 "malloc() failed for SMTP command buffer");
1433 smtp_cmd_buffer[0] = 0;
1434 smtp_data_buffer = smtp_cmd_buffer + smtp_cmd_buffer_size + 1;
1436 /* For batched input, the protocol setting can be overridden from the
1437 command line by a trusted caller. */
1439 if (smtp_batched_input)
1441 if (received_protocol == NULL) received_protocol = US"local-bsmtp";
1444 /* For non-batched SMTP input, the protocol setting is forced here. It will be
1445 reset later if any of EHLO/AUTH/STARTTLS are received. */
1449 protocols[pnormal] + ((sender_host_address != NULL)? pnlocal : 0);
1451 /* Set up the buffer for inputting using direct read() calls, and arrange to
1452 call the local functions instead of the standard C ones. */
1454 smtp_inbuffer = (uschar *)malloc(in_buffer_size);
1455 if (smtp_inbuffer == NULL)
1456 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "malloc() failed for SMTP input buffer");
1457 receive_getc = smtp_getc;
1458 receive_ungetc = smtp_ungetc;
1459 receive_feof = smtp_feof;
1460 receive_ferror = smtp_ferror;
1461 receive_smtp_buffered = smtp_buffered;
1462 smtp_inptr = smtp_inend = smtp_inbuffer;
1463 smtp_had_eof = smtp_had_error = 0;
1465 /* Set up the message size limit; this may be host-specific */
1467 thismessage_size_limit = expand_string_integer(message_size_limit, TRUE);
1468 if (expand_string_message != NULL)
1470 if (thismessage_size_limit == -1)
1471 log_write(0, LOG_MAIN|LOG_PANIC, "unable to expand message_size_limit: "
1472 "%s", expand_string_message);
1474 log_write(0, LOG_MAIN|LOG_PANIC, "invalid message_size_limit: "
1475 "%s", expand_string_message);
1476 smtp_closedown(US"Temporary local problem - please try later");
1480 /* When a message is input locally via the -bs or -bS options, sender_host_
1481 unknown is set unless -oMa was used to force an IP address, in which case it
1482 is checked like a real remote connection. When -bs is used from inetd, this
1483 flag is not set, causing the sending host to be checked. The code that deals
1484 with IP source routing (if configured) is never required for -bs or -bS and
1485 the flag sender_host_notsocket is used to suppress it.
1487 If smtp_accept_max and smtp_accept_reserve are set, keep some connections in
1488 reserve for certain hosts and/or networks. */
1490 if (!sender_host_unknown)
1493 BOOL reserved_host = FALSE;
1495 /* Look up IP options (source routing info) on the socket if this is not an
1496 -oMa "host", and if any are found, log them and drop the connection.
1498 Linux (and others now, see below) is different to everyone else, so there
1499 has to be some conditional compilation here. Versions of Linux before 2.1.15
1500 used a structure whose name was "options". Somebody finally realized that
1501 this name was silly, and it got changed to "ip_options". I use the
1502 newer name here, but there is a fudge in the script that sets up os.h
1503 to define a macro in older Linux systems.
1505 Sigh. Linux is a fast-moving target. Another generation of Linux uses
1506 glibc 2, which has chosen ip_opts for the structure name. This is now
1507 really a glibc thing rather than a Linux thing, so the condition name
1508 has been changed to reflect this. It is relevant also to GNU/Hurd.
1510 Mac OS 10.x (Darwin) is like the later glibc versions, but without the
1511 setting of the __GLIBC__ macro, so we can't detect it automatically. There's
1512 a special macro defined in the os.h file.
1514 Some DGUX versions on older hardware appear not to support IP options at
1515 all, so there is now a general macro which can be set to cut out this
1518 How to do this properly in IPv6 is not yet known. */
1520 #if !HAVE_IPV6 && !defined(NO_IP_OPTIONS)
1522 #ifdef GLIBC_IP_OPTIONS
1523 #if (!defined __GLIBC__) || (__GLIBC__ < 2)
1528 #elif defined DARWIN_IP_OPTIONS
1534 if (!host_checking && !sender_host_notsocket)
1537 EXIM_SOCKLEN_T optlen = sizeof(struct ip_options) + MAX_IPOPTLEN;
1538 struct ip_options *ipopt = store_get(optlen);
1540 struct ip_opts ipoptblock;
1541 struct ip_opts *ipopt = &ipoptblock;
1542 EXIM_SOCKLEN_T optlen = sizeof(ipoptblock);
1544 struct ipoption ipoptblock;
1545 struct ipoption *ipopt = &ipoptblock;
1546 EXIM_SOCKLEN_T optlen = sizeof(ipoptblock);
1549 /* Occasional genuine failures of getsockopt() have been seen - for
1550 example, "reset by peer". Therefore, just log and give up on this
1551 call, unless the error is ENOPROTOOPT. This error is given by systems
1552 that have the interfaces but not the mechanism - e.g. GNU/Hurd at the time
1553 of writing. So for that error, carry on - we just can't do an IP options
1556 DEBUG(D_receive) debug_printf("checking for IP options\n");
1558 if (getsockopt(fileno(smtp_out), IPPROTO_IP, IP_OPTIONS, (uschar *)(ipopt),
1561 if (errno != ENOPROTOOPT)
1563 log_write(0, LOG_MAIN, "getsockopt() failed from %s: %s",
1564 host_and_ident(FALSE), strerror(errno));
1565 smtp_printf("451 SMTP service not available\r\n");
1570 /* Deal with any IP options that are set. On the systems I have looked at,
1571 the value of MAX_IPOPTLEN has been 40, meaning that there should never be
1572 more logging data than will fit in big_buffer. Nevertheless, after somebody
1573 questioned this code, I've added in some paranoid checking. */
1575 else if (optlen > 0)
1577 uschar *p = big_buffer;
1578 uschar *pend = big_buffer + big_buffer_size;
1579 uschar *opt, *adptr;
1581 struct in_addr addr;
1584 uschar *optstart = (uschar *)(ipopt->__data);
1586 uschar *optstart = (uschar *)(ipopt->ip_opts);
1588 uschar *optstart = (uschar *)(ipopt->ipopt_list);
1591 DEBUG(D_receive) debug_printf("IP options exist\n");
1593 Ustrcpy(p, "IP options on incoming call:");
1596 for (opt = optstart; opt != NULL &&
1597 opt < (uschar *)(ipopt) + optlen;)
1611 if (!string_format(p, pend-p, " %s [@%s",
1612 (*opt == IPOPT_SSRR)? "SSRR" : "LSRR",
1614 inet_ntoa(*((struct in_addr *)(&(ipopt->faddr))))))
1616 inet_ntoa(ipopt->ip_dst)))
1618 inet_ntoa(ipopt->ipopt_dst)))
1626 optcount = (opt[1] - 3) / sizeof(struct in_addr);
1628 while (optcount-- > 0)
1630 memcpy(&addr, adptr, sizeof(addr));
1631 if (!string_format(p, pend - p - 1, "%s%s",
1632 (optcount == 0)? ":" : "@", inet_ntoa(addr)))
1638 adptr += sizeof(struct in_addr);
1647 if (pend - p < 4 + 3*opt[1]) { opt = NULL; break; }
1650 for (i = 0; i < opt[1]; i++)
1652 sprintf(CS p, "%2.2x ", opt[i]);
1663 log_write(0, LOG_MAIN, "%s", big_buffer);
1665 /* Refuse any call with IP options. This is what tcpwrappers 7.5 does. */
1667 log_write(0, LOG_MAIN|LOG_REJECT,
1668 "connection from %s refused (IP options)", host_and_ident(FALSE));
1670 smtp_printf("554 SMTP service not available\r\n");
1674 /* Length of options = 0 => there are no options */
1676 else DEBUG(D_receive) debug_printf("no IP options found\n");
1678 #endif /* HAVE_IPV6 && !defined(NO_IP_OPTIONS) */
1680 /* Set keep-alive in socket options. The option is on by default. This
1681 setting is an attempt to get rid of some hanging connections that stick in
1682 read() when the remote end (usually a dialup) goes away. */
1684 if (smtp_accept_keepalive && !sender_host_notsocket)
1685 ip_keepalive(fileno(smtp_out), sender_host_address, FALSE);
1687 /* If the current host matches host_lookup, set the name by doing a
1688 reverse lookup. On failure, sender_host_name will be NULL and
1689 host_lookup_failed will be TRUE. This may or may not be serious - optional
1692 if (verify_check_host(&host_lookup) == OK)
1694 (void)host_name_lookup();
1695 host_build_sender_fullhost();
1698 /* Delay this until we have the full name, if it is looked up. */
1700 set_process_info("handling incoming connection from %s",
1701 host_and_ident(FALSE));
1703 /* Start up TLS if tls_on_connect is set. This is for supporting the legacy
1704 smtps port for use with older style SSL MTAs. */
1707 if (tls_in.on_connect && tls_server_start(tls_require_ciphers) != OK)
1711 /* Test for explicit connection rejection */
1713 if (verify_check_host(&host_reject_connection) == OK)
1715 log_write(L_connection_reject, LOG_MAIN|LOG_REJECT, "refused connection "
1716 "from %s (host_reject_connection)", host_and_ident(FALSE));
1717 smtp_printf("554 SMTP service not available\r\n");
1721 /* Test with TCP Wrappers if so configured. There is a problem in that
1722 hosts_ctl() returns 0 (deny) under a number of system failure circumstances,
1723 such as disks dying. In these cases, it is desirable to reject with a 4xx
1724 error instead of a 5xx error. There isn't a "right" way to detect such
1725 problems. The following kludge is used: errno is zeroed before calling
1726 hosts_ctl(). If the result is "reject", a 5xx error is given only if the
1727 value of errno is 0 or ENOENT (which happens if /etc/hosts.{allow,deny} does
1730 #ifdef USE_TCP_WRAPPERS
1732 tcp_wrappers_name = expand_string(tcp_wrappers_daemon_name);
1733 if (tcp_wrappers_name == NULL)
1735 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "Expansion of \"%s\" "
1736 "(tcp_wrappers_name) failed: %s", string_printing(tcp_wrappers_name),
1737 expand_string_message);
1739 if (!hosts_ctl(tcp_wrappers_name,
1740 (sender_host_name == NULL)? STRING_UNKNOWN : CS sender_host_name,
1741 (sender_host_address == NULL)? STRING_UNKNOWN : CS sender_host_address,
1742 (sender_ident == NULL)? STRING_UNKNOWN : CS sender_ident))
1744 if (errno == 0 || errno == ENOENT)
1746 HDEBUG(D_receive) debug_printf("tcp wrappers rejection\n");
1747 log_write(L_connection_reject,
1748 LOG_MAIN|LOG_REJECT, "refused connection from %s "
1749 "(tcp wrappers)", host_and_ident(FALSE));
1750 smtp_printf("554 SMTP service not available\r\n");
1754 int save_errno = errno;
1755 HDEBUG(D_receive) debug_printf("tcp wrappers rejected with unexpected "
1756 "errno value %d\n", save_errno);
1757 log_write(L_connection_reject,
1758 LOG_MAIN|LOG_REJECT, "temporarily refused connection from %s "
1759 "(tcp wrappers errno=%d)", host_and_ident(FALSE), save_errno);
1760 smtp_printf("451 Temporary local problem - please try later\r\n");
1766 /* Check for reserved slots. The value of smtp_accept_count has already been
1767 incremented to include this process. */
1769 if (smtp_accept_max > 0 &&
1770 smtp_accept_count > smtp_accept_max - smtp_accept_reserve)
1772 if ((rc = verify_check_host(&smtp_reserve_hosts)) != OK)
1774 log_write(L_connection_reject,
1775 LOG_MAIN, "temporarily refused connection from %s: not in "
1776 "reserve list: connected=%d max=%d reserve=%d%s",
1777 host_and_ident(FALSE), smtp_accept_count - 1, smtp_accept_max,
1778 smtp_accept_reserve, (rc == DEFER)? " (lookup deferred)" : "");
1779 smtp_printf("421 %s: Too many concurrent SMTP connections; "
1780 "please try again later\r\n", smtp_active_hostname);
1783 reserved_host = TRUE;
1786 /* If a load level above which only messages from reserved hosts are
1787 accepted is set, check the load. For incoming calls via the daemon, the
1788 check is done in the superior process if there are no reserved hosts, to
1789 save a fork. In all cases, the load average will already be available
1790 in a global variable at this point. */
1792 if (smtp_load_reserve >= 0 &&
1793 load_average > smtp_load_reserve &&
1795 verify_check_host(&smtp_reserve_hosts) != OK)
1797 log_write(L_connection_reject,
1798 LOG_MAIN, "temporarily refused connection from %s: not in "
1799 "reserve list and load average = %.2f", host_and_ident(FALSE),
1800 (double)load_average/1000.0);
1801 smtp_printf("421 %s: Too much load; please try again later\r\n",
1802 smtp_active_hostname);
1806 /* Determine whether unqualified senders or recipients are permitted
1807 for this host. Unfortunately, we have to do this every time, in order to
1808 set the flags so that they can be inspected when considering qualifying
1809 addresses in the headers. For a site that permits no qualification, this
1810 won't take long, however. */
1812 allow_unqualified_sender =
1813 verify_check_host(&sender_unqualified_hosts) == OK;
1815 allow_unqualified_recipient =
1816 verify_check_host(&recipient_unqualified_hosts) == OK;
1818 /* Determine whether HELO/EHLO is required for this host. The requirement
1819 can be hard or soft. */
1821 helo_required = verify_check_host(&helo_verify_hosts) == OK;
1823 helo_verify = verify_check_host(&helo_try_verify_hosts) == OK;
1825 /* Determine whether this hosts is permitted to send syntactic junk
1826 after a HELO or EHLO command. */
1828 helo_accept_junk = verify_check_host(&helo_accept_junk_hosts) == OK;
1831 /* For batch SMTP input we are now done. */
1833 if (smtp_batched_input) return TRUE;
1835 /* Run the ACL if it exists */
1838 if (acl_smtp_connect != NULL)
1841 rc = acl_check(ACL_WHERE_CONNECT, NULL, acl_smtp_connect, &user_msg,
1845 (void)smtp_handle_acl_fail(ACL_WHERE_CONNECT, rc, user_msg, log_msg);
1850 /* Output the initial message for a two-way SMTP connection. It may contain
1851 newlines, which then cause a multi-line response to be given. */
1853 code = US"220"; /* Default status code */
1854 esc = US""; /* Default extended status code */
1855 esclen = 0; /* Length of esc */
1857 if (user_msg == NULL)
1859 s = expand_string(smtp_banner);
1861 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "Expansion of \"%s\" (smtp_banner) "
1862 "failed: %s", smtp_banner, expand_string_message);
1868 smtp_message_code(&code, &codelen, &s, NULL);
1872 esclen = codelen - 4;
1876 /* Remove any terminating newlines; might as well remove trailing space too */
1879 while (p > s && isspace(p[-1])) p--;
1882 /* It seems that CC:Mail is braindead, and assumes that the greeting message
1883 is all contained in a single IP packet. The original code wrote out the
1884 greeting using several calls to fprint/fputc, and on busy servers this could
1885 cause it to be split over more than one packet - which caused CC:Mail to fall
1886 over when it got the second part of the greeting after sending its first
1887 command. Sigh. To try to avoid this, build the complete greeting message
1888 first, and output it in one fell swoop. This gives a better chance of it
1889 ending up as a single packet. */
1891 ss = store_get(size);
1895 do /* At least once, in case we have an empty string */
1898 uschar *linebreak = Ustrchr(p, '\n');
1899 ss = string_cat(ss, &size, &ptr, code, 3);
1900 if (linebreak == NULL)
1903 ss = string_cat(ss, &size, &ptr, US" ", 1);
1907 len = linebreak - p;
1908 ss = string_cat(ss, &size, &ptr, US"-", 1);
1910 ss = string_cat(ss, &size, &ptr, esc, esclen);
1911 ss = string_cat(ss, &size, &ptr, p, len);
1912 ss = string_cat(ss, &size, &ptr, US"\r\n", 2);
1914 if (linebreak != NULL) p++;
1918 ss[ptr] = 0; /* string_cat leaves room for this */
1920 /* Before we write the banner, check that there is no input pending, unless
1921 this synchronisation check is disabled. */
1925 log_write(0, LOG_MAIN|LOG_REJECT, "SMTP protocol "
1926 "synchronization error (input sent without waiting for greeting): "
1927 "rejected connection from %s input=\"%s\"", host_and_ident(TRUE),
1928 string_printing(smtp_inptr));
1929 smtp_printf("554 SMTP synchronization error\r\n");
1933 /* Now output the banner */
1935 smtp_printf("%s", ss);
1943 /*************************************************
1944 * Handle SMTP syntax and protocol errors *
1945 *************************************************/
1947 /* Write to the log for SMTP syntax errors in incoming commands, if configured
1948 to do so. Then transmit the error response. The return value depends on the
1949 number of syntax and protocol errors in this SMTP session.
1952 type error type, given as a log flag bit
1953 code response code; <= 0 means don't send a response
1954 data data to reflect in the response (can be NULL)
1955 errmess the error message
1957 Returns: -1 limit of syntax/protocol errors NOT exceeded
1958 +1 limit of syntax/protocol errors IS exceeded
1960 These values fit in with the values of the "done" variable in the main
1961 processing loop in smtp_setup_msg(). */
1964 synprot_error(int type, int code, uschar *data, uschar *errmess)
1968 log_write(type, LOG_MAIN, "SMTP %s error in \"%s\" %s %s",
1969 (type == L_smtp_syntax_error)? "syntax" : "protocol",
1970 string_printing(smtp_cmd_buffer), host_and_ident(TRUE), errmess);
1972 if (++synprot_error_count > smtp_max_synprot_errors)
1975 log_write(0, LOG_MAIN|LOG_REJECT, "SMTP call from %s dropped: too many "
1976 "syntax or protocol errors (last command was \"%s\")",
1977 host_and_ident(FALSE), smtp_cmd_buffer);
1982 smtp_printf("%d%c%s%s%s\r\n", code, (yield == 1)? '-' : ' ',
1983 (data == NULL)? US"" : data, (data == NULL)? US"" : US": ", errmess);
1985 smtp_printf("%d Too many syntax or protocol errors\r\n", code);
1994 /*************************************************
1995 * Log incomplete transactions *
1996 *************************************************/
1998 /* This function is called after a transaction has been aborted by RSET, QUIT,
1999 connection drops or other errors. It logs the envelope information received
2000 so far in order to preserve address verification attempts.
2002 Argument: string to indicate what aborted the transaction
2007 incomplete_transaction_log(uschar *what)
2009 if (sender_address == NULL || /* No transaction in progress */
2010 (log_write_selector & L_smtp_incomplete_transaction) == 0 /* Not logging */
2013 /* Build list of recipients for logging */
2015 if (recipients_count > 0)
2018 raw_recipients = store_get(recipients_count * sizeof(uschar *));
2019 for (i = 0; i < recipients_count; i++)
2020 raw_recipients[i] = recipients_list[i].address;
2021 raw_recipients_count = recipients_count;
2024 log_write(L_smtp_incomplete_transaction, LOG_MAIN|LOG_SENDER|LOG_RECIPIENTS,
2025 "%s incomplete transaction (%s)", host_and_ident(TRUE), what);
2031 /*************************************************
2032 * Send SMTP response, possibly multiline *
2033 *************************************************/
2035 /* There are, it seems, broken clients out there that cannot handle multiline
2036 responses. If no_multiline_responses is TRUE (it can be set from an ACL), we
2037 output nothing for non-final calls, and only the first line for anything else.
2040 code SMTP code, may involve extended status codes
2041 codelen length of smtp code; if > 4 there's an ESC
2042 final FALSE if the last line isn't the final line
2043 msg message text, possibly containing newlines
2049 smtp_respond(uschar* code, int codelen, BOOL final, uschar *msg)
2054 if (!final && no_multiline_responses) return;
2059 esclen = codelen - 4;
2062 /* If this is the first output for a (non-batch) RCPT command, see if all RCPTs
2063 have had the same. Note: this code is also present in smtp_printf(). It would
2064 be tidier to have it only in one place, but when it was added, it was easier to
2065 do it that way, so as not to have to mess with the code for the RCPT command,
2066 which sometimes uses smtp_printf() and sometimes smtp_respond(). */
2068 if (rcpt_in_progress)
2070 if (rcpt_smtp_response == NULL)
2071 rcpt_smtp_response = string_copy(msg);
2072 else if (rcpt_smtp_response_same &&
2073 Ustrcmp(rcpt_smtp_response, msg) != 0)
2074 rcpt_smtp_response_same = FALSE;
2075 rcpt_in_progress = FALSE;
2078 /* Not output the message, splitting it up into multiple lines if necessary. */
2082 uschar *nl = Ustrchr(msg, '\n');
2085 smtp_printf("%.3s%c%.*s%s\r\n", code, final? ' ':'-', esclen, esc, msg);
2088 else if (nl[1] == 0 || no_multiline_responses)
2090 smtp_printf("%.3s%c%.*s%.*s\r\n", code, final? ' ':'-', esclen, esc,
2091 (int)(nl - msg), msg);
2096 smtp_printf("%.3s-%.*s%.*s\r\n", code, esclen, esc, (int)(nl - msg), msg);
2098 while (isspace(*msg)) msg++;
2106 /*************************************************
2107 * Parse user SMTP message *
2108 *************************************************/
2110 /* This function allows for user messages overriding the response code details
2111 by providing a suitable response code string at the start of the message
2112 user_msg. Check the message for starting with a response code and optionally an
2113 extended status code. If found, check that the first digit is valid, and if so,
2114 change the code pointer and length to use the replacement. An invalid code
2115 causes a panic log; in this case, if the log messages is the same as the user
2116 message, we must also adjust the value of the log message to show the code that
2117 is actually going to be used (the original one).
2119 This function is global because it is called from receive.c as well as within
2122 Note that the code length returned includes the terminating whitespace
2123 character, which is always included in the regex match.
2126 code SMTP code, may involve extended status codes
2127 codelen length of smtp code; if > 4 there's an ESC
2129 log_msg optional log message, to be adjusted with the new SMTP code
2135 smtp_message_code(uschar **code, int *codelen, uschar **msg, uschar **log_msg)
2140 if (msg == NULL || *msg == NULL) return;
2142 n = pcre_exec(regex_smtp_code, NULL, CS *msg, Ustrlen(*msg), 0,
2143 PCRE_EOPT, ovector, sizeof(ovector)/sizeof(int));
2146 if ((*msg)[0] != (*code)[0])
2148 log_write(0, LOG_MAIN|LOG_PANIC, "configured error code starts with "
2149 "incorrect digit (expected %c) in \"%s\"", (*code)[0], *msg);
2150 if (log_msg != NULL && *log_msg == *msg)
2151 *log_msg = string_sprintf("%s %s", *code, *log_msg + ovector[1]);
2156 *codelen = ovector[1]; /* Includes final space */
2158 *msg += ovector[1]; /* Chop the code off the message */
2165 /*************************************************
2166 * Handle an ACL failure *
2167 *************************************************/
2169 /* This function is called when acl_check() fails. As well as calls from within
2170 this module, it is called from receive.c for an ACL after DATA. It sorts out
2171 logging the incident, and sets up the error response. A message containing
2172 newlines is turned into a multiline SMTP response, but for logging, only the
2175 There's a table of default permanent failure response codes to use in
2176 globals.c, along with the table of names. VFRY is special. Despite RFC1123 it
2177 defaults disabled in Exim. However, discussion in connection with RFC 821bis
2178 (aka RFC 2821) has concluded that the response should be 252 in the disabled
2179 state, because there are broken clients that try VRFY before RCPT. A 5xx
2180 response should be given only when the address is positively known to be
2181 undeliverable. Sigh. Also, for ETRN, 458 is given on refusal, and for AUTH,
2184 From Exim 4.63, it is possible to override the response code details by
2185 providing a suitable response code string at the start of the message provided
2186 in user_msg. The code's first digit is checked for validity.
2189 where where the ACL was called from
2191 user_msg a message that can be included in an SMTP response
2192 log_msg a message for logging
2194 Returns: 0 in most cases
2195 2 if the failure code was FAIL_DROP, in which case the
2196 SMTP connection should be dropped (this value fits with the
2197 "done" variable in smtp_setup_msg() below)
2201 smtp_handle_acl_fail(int where, int rc, uschar *user_msg, uschar *log_msg)
2203 BOOL drop = rc == FAIL_DROP;
2207 uschar *sender_info = US"";
2209 #ifdef WITH_CONTENT_SCAN
2210 (where == ACL_WHERE_MIME)? US"during MIME ACL checks" :
2212 (where == ACL_WHERE_PREDATA)? US"DATA" :
2213 (where == ACL_WHERE_DATA)? US"after DATA" :
2214 #ifdef EXPERIMENTAL_PRDR
2215 (where == ACL_WHERE_PRDR)? US"after DATA PRDR" :
2217 (smtp_cmd_data == NULL)?
2218 string_sprintf("%s in \"connect\" ACL", acl_wherenames[where]) :
2219 string_sprintf("%s %s", acl_wherenames[where], smtp_cmd_data);
2221 if (drop) rc = FAIL;
2223 /* Set the default SMTP code, and allow a user message to change it. */
2225 smtp_code = (rc != FAIL)? US"451" : acl_wherecodes[where];
2226 smtp_message_code(&smtp_code, &codelen, &user_msg, &log_msg);
2228 /* We used to have sender_address here; however, there was a bug that was not
2229 updating sender_address after a rewrite during a verify. When this bug was
2230 fixed, sender_address at this point became the rewritten address. I'm not sure
2231 this is what should be logged, so I've changed to logging the unrewritten
2232 address to retain backward compatibility. */
2234 #ifndef WITH_CONTENT_SCAN
2235 if (where == ACL_WHERE_RCPT || where == ACL_WHERE_DATA)
2237 if (where == ACL_WHERE_RCPT || where == ACL_WHERE_DATA || where == ACL_WHERE_MIME)
2240 sender_info = string_sprintf("F=<%s>%s%s%s%s ",
2241 sender_address_unrewritten ? sender_address_unrewritten : sender_address,
2242 sender_host_authenticated ? US" A=" : US"",
2243 sender_host_authenticated ? sender_host_authenticated : US"",
2244 sender_host_authenticated && authenticated_id ? US":" : US"",
2245 sender_host_authenticated && authenticated_id ? authenticated_id : US""
2249 /* If there's been a sender verification failure with a specific message, and
2250 we have not sent a response about it yet, do so now, as a preliminary line for
2251 failures, but not defers. However, always log it for defer, and log it for fail
2252 unless the sender_verify_fail log selector has been turned off. */
2254 if (sender_verified_failed != NULL &&
2255 !testflag(sender_verified_failed, af_sverify_told))
2257 BOOL save_rcpt_in_progress = rcpt_in_progress;
2258 rcpt_in_progress = FALSE; /* So as not to treat these as the error */
2260 setflag(sender_verified_failed, af_sverify_told);
2262 if (rc != FAIL || (log_extra_selector & LX_sender_verify_fail) != 0)
2263 log_write(0, LOG_MAIN|LOG_REJECT, "%s sender verify %s for <%s>%s",
2264 host_and_ident(TRUE),
2265 ((sender_verified_failed->special_action & 255) == DEFER)? "defer":"fail",
2266 sender_verified_failed->address,
2267 (sender_verified_failed->message == NULL)? US"" :
2268 string_sprintf(": %s", sender_verified_failed->message));
2270 if (rc == FAIL && sender_verified_failed->user_message != NULL)
2271 smtp_respond(smtp_code, codelen, FALSE, string_sprintf(
2272 testflag(sender_verified_failed, af_verify_pmfail)?
2273 "Postmaster verification failed while checking <%s>\n%s\n"
2274 "Several RFCs state that you are required to have a postmaster\n"
2275 "mailbox for each mail domain. This host does not accept mail\n"
2276 "from domains whose servers reject the postmaster address."
2278 testflag(sender_verified_failed, af_verify_nsfail)?
2279 "Callback setup failed while verifying <%s>\n%s\n"
2280 "The initial connection, or a HELO or MAIL FROM:<> command was\n"
2281 "rejected. Refusing MAIL FROM:<> does not help fight spam, disregards\n"
2282 "RFC requirements, and stops you from receiving standard bounce\n"
2283 "messages. This host does not accept mail from domains whose servers\n"
2286 "Verification failed for <%s>\n%s",
2287 sender_verified_failed->address,
2288 sender_verified_failed->user_message));
2290 rcpt_in_progress = save_rcpt_in_progress;
2293 /* Sort out text for logging */
2295 log_msg = (log_msg == NULL)? US"" : string_sprintf(": %s", log_msg);
2296 lognl = Ustrchr(log_msg, '\n');
2297 if (lognl != NULL) *lognl = 0;
2299 /* Send permanent failure response to the command, but the code used isn't
2300 always a 5xx one - see comments at the start of this function. If the original
2301 rc was FAIL_DROP we drop the connection and yield 2. */
2303 if (rc == FAIL) smtp_respond(smtp_code, codelen, TRUE, (user_msg == NULL)?
2304 US"Administrative prohibition" : user_msg);
2306 /* Send temporary failure response to the command. Don't give any details,
2307 unless acl_temp_details is set. This is TRUE for a callout defer, a "defer"
2308 verb, and for a header verify when smtp_return_error_details is set.
2310 This conditional logic is all somewhat of a mess because of the odd
2311 interactions between temp_details and return_error_details. One day it should
2312 be re-implemented in a tidier fashion. */
2316 if (acl_temp_details && user_msg != NULL)
2318 if (smtp_return_error_details &&
2319 sender_verified_failed != NULL &&
2320 sender_verified_failed->message != NULL)
2322 smtp_respond(smtp_code, codelen, FALSE, sender_verified_failed->message);
2324 smtp_respond(smtp_code, codelen, TRUE, user_msg);
2327 smtp_respond(smtp_code, codelen, TRUE,
2328 US"Temporary local problem - please try later");
2331 /* Log the incident to the logs that are specified by log_reject_target
2332 (default main, reject). This can be empty to suppress logging of rejections. If
2333 the connection is not forcibly to be dropped, return 0. Otherwise, log why it
2334 is closing if required and return 2. */
2336 if (log_reject_target != 0)
2337 log_write(0, log_reject_target, "%s %s%srejected %s%s",
2338 host_and_ident(TRUE),
2339 sender_info, (rc == FAIL)? US"" : US"temporarily ", what, log_msg);
2341 if (!drop) return 0;
2343 log_write(L_smtp_connection, LOG_MAIN, "%s closed by DROP in ACL",
2344 smtp_get_connection_info());
2346 /* Run the not-quit ACL, but without any custom messages. This should not be a
2347 problem, because we get here only if some other ACL has issued "drop", and
2348 in that case, *its* custom messages will have been used above. */
2350 smtp_notquit_exit(US"acl-drop", NULL, NULL);
2357 /*************************************************
2358 * Handle SMTP exit when QUIT is not given *
2359 *************************************************/
2361 /* This function provides a logging/statistics hook for when an SMTP connection
2362 is dropped on the floor or the other end goes away. It's a global function
2363 because it's called from receive.c as well as this module. As well as running
2364 the NOTQUIT ACL, if there is one, this function also outputs a final SMTP
2365 response, either with a custom message from the ACL, or using a default. There
2366 is one case, however, when no message is output - after "drop". In that case,
2367 the ACL that obeyed "drop" has already supplied the custom message, and NULL is
2368 passed to this function.
2370 In case things go wrong while processing this function, causing an error that
2371 may re-enter this funtion, there is a recursion check.
2374 reason What $smtp_notquit_reason will be set to in the ACL;
2375 if NULL, the ACL is not run
2376 code The error code to return as part of the response
2377 defaultrespond The default message if there's no user_msg
2383 smtp_notquit_exit(uschar *reason, uschar *code, uschar *defaultrespond, ...)
2386 uschar *user_msg = NULL;
2387 uschar *log_msg = NULL;
2389 /* Check for recursive acll */
2391 if (smtp_exit_function_called)
2393 log_write(0, LOG_PANIC, "smtp_notquit_exit() called more than once (%s)",
2397 smtp_exit_function_called = TRUE;
2399 /* Call the not-QUIT ACL, if there is one, unless no reason is given. */
2401 if (acl_smtp_notquit != NULL && reason != NULL)
2403 smtp_notquit_reason = reason;
2404 rc = acl_check(ACL_WHERE_NOTQUIT, NULL, acl_smtp_notquit, &user_msg,
2407 log_write(0, LOG_MAIN|LOG_PANIC, "ACL for not-QUIT returned ERROR: %s",
2411 /* Write an SMTP response if we are expected to give one. As the default
2412 responses are all internal, they should always fit in the buffer, but code a
2413 warning, just in case. Note that string_vformat() still leaves a complete
2414 string, even if it is incomplete. */
2416 if (code != NULL && defaultrespond != NULL)
2418 if (user_msg == NULL)
2422 va_start(ap, defaultrespond);
2423 if (!string_vformat(buffer, sizeof(buffer), CS defaultrespond, ap))
2424 log_write(0, LOG_MAIN|LOG_PANIC, "string too large in smtp_notquit_exit()");
2425 smtp_printf("%s %s\r\n", code, buffer);
2429 smtp_respond(code, 3, TRUE, user_msg);
2437 /*************************************************
2438 * Verify HELO argument *
2439 *************************************************/
2441 /* This function is called if helo_verify_hosts or helo_try_verify_hosts is
2442 matched. It is also called from ACL processing if verify = helo is used and
2443 verification was not previously tried (i.e. helo_try_verify_hosts was not
2444 matched). The result of its processing is to set helo_verified and
2445 helo_verify_failed. These variables should both be FALSE for this function to
2448 Note that EHLO/HELO is legitimately allowed to quote an address literal. Allow
2449 for IPv6 ::ffff: literals.
2452 Returns: TRUE if testing was completed;
2453 FALSE on a temporary failure
2457 smtp_verify_helo(void)
2461 HDEBUG(D_receive) debug_printf("verifying EHLO/HELO argument \"%s\"\n",
2464 if (sender_helo_name == NULL)
2466 HDEBUG(D_receive) debug_printf("no EHLO/HELO command was issued\n");
2469 /* Deal with the case of -bs without an IP address */
2471 else if (sender_host_address == NULL)
2473 HDEBUG(D_receive) debug_printf("no client IP address: assume success\n");
2474 helo_verified = TRUE;
2477 /* Deal with the more common case when there is a sending IP address */
2479 else if (sender_helo_name[0] == '[')
2481 helo_verified = Ustrncmp(sender_helo_name+1, sender_host_address,
2482 Ustrlen(sender_host_address)) == 0;
2487 if (strncmpic(sender_host_address, US"::ffff:", 7) == 0)
2488 helo_verified = Ustrncmp(sender_helo_name + 1,
2489 sender_host_address + 7, Ustrlen(sender_host_address) - 7) == 0;
2494 { if (helo_verified) debug_printf("matched host address\n"); }
2497 /* Do a reverse lookup if one hasn't already given a positive or negative
2498 response. If that fails, or the name doesn't match, try checking with a forward
2503 if (sender_host_name == NULL && !host_lookup_failed)
2504 yield = host_name_lookup() != DEFER;
2506 /* If a host name is known, check it and all its aliases. */
2508 if (sender_host_name != NULL)
2510 helo_verified = strcmpic(sender_host_name, sender_helo_name) == 0;
2514 HDEBUG(D_receive) debug_printf("matched host name\n");
2518 uschar **aliases = sender_host_aliases;
2519 while (*aliases != NULL)
2521 helo_verified = strcmpic(*aliases++, sender_helo_name) == 0;
2522 if (helo_verified) break;
2527 debug_printf("matched alias %s\n", *(--aliases));
2532 /* Final attempt: try a forward lookup of the helo name */
2538 h.name = sender_helo_name;
2542 HDEBUG(D_receive) debug_printf("getting IP address for %s\n",
2544 rc = host_find_byname(&h, NULL, 0, NULL, TRUE);
2545 if (rc == HOST_FOUND || rc == HOST_FOUND_LOCAL)
2550 if (Ustrcmp(hh->address, sender_host_address) == 0)
2552 helo_verified = TRUE;
2554 debug_printf("IP address for %s matches calling address\n",
2564 if (!helo_verified) helo_verify_failed = TRUE; /* We've tried ... */
2571 /*************************************************
2572 * Send user response message *
2573 *************************************************/
2575 /* This function is passed a default response code and a user message. It calls
2576 smtp_message_code() to check and possibly modify the response code, and then
2577 calls smtp_respond() to transmit the response. I put this into a function
2578 just to avoid a lot of repetition.
2581 code the response code
2582 user_msg the user message
2588 smtp_user_msg(uschar *code, uschar *user_msg)
2591 smtp_message_code(&code, &len, &user_msg, NULL);
2592 smtp_respond(code, len, TRUE, user_msg);
2598 /*************************************************
2599 * Initialize for SMTP incoming message *
2600 *************************************************/
2602 /* This function conducts the initial dialogue at the start of an incoming SMTP
2603 message, and builds a list of recipients. However, if the incoming message
2604 is part of a batch (-bS option) a separate function is called since it would
2605 be messy having tests splattered about all over this function. This function
2606 therefore handles the case where interaction is occurring. The input and output
2607 files are set up in smtp_in and smtp_out.
2609 The global recipients_list is set to point to a vector of recipient_item
2610 blocks, whose number is given by recipients_count. This is extended by the
2611 receive_add_recipient() function. The global variable sender_address is set to
2612 the sender's address. The yield is +1 if a message has been successfully
2613 started, 0 if a QUIT command was encountered or the connection was refused from
2614 the particular host, or -1 if the connection was lost.
2618 Returns: > 0 message successfully started (reached DATA)
2619 = 0 QUIT read or end of file reached or call refused
2624 smtp_setup_msg(void)
2627 BOOL toomany = FALSE;
2628 BOOL discarded = FALSE;
2629 BOOL last_was_rej_mail = FALSE;
2630 BOOL last_was_rcpt = FALSE;
2631 void *reset_point = store_get(0);
2633 DEBUG(D_receive) debug_printf("smtp_setup_msg entered\n");
2635 /* Reset for start of new message. We allow one RSET not to be counted as a
2636 nonmail command, for those MTAs that insist on sending it between every
2637 message. Ditto for EHLO/HELO and for STARTTLS, to allow for going in and out of
2638 TLS between messages (an Exim client may do this if it has messages queued up
2639 for the host). Note: we do NOT reset AUTH at this point. */
2641 smtp_reset(reset_point);
2642 message_ended = END_NOTSTARTED;
2644 cmd_list[CMD_LIST_RSET].is_mail_cmd = TRUE;
2645 cmd_list[CMD_LIST_HELO].is_mail_cmd = TRUE;
2646 cmd_list[CMD_LIST_EHLO].is_mail_cmd = TRUE;
2648 cmd_list[CMD_LIST_STARTTLS].is_mail_cmd = TRUE;
2651 /* Set the local signal handler for SIGTERM - it tries to end off tidily */
2653 os_non_restarting_signal(SIGTERM, command_sigterm_handler);
2655 /* Batched SMTP is handled in a different function. */
2657 if (smtp_batched_input) return smtp_setup_batch_msg();
2659 /* Deal with SMTP commands. This loop is exited by setting done to a POSITIVE
2660 value. The values are 2 larger than the required yield of the function. */
2665 uschar *etrn_command;
2666 uschar *etrn_serialize_key;
2668 uschar *log_msg, *smtp_code;
2669 uschar *user_msg = NULL;
2670 uschar *recipient = NULL;
2671 uschar *hello = NULL;
2672 uschar *set_id = NULL;
2674 BOOL was_rej_mail = FALSE;
2675 BOOL was_rcpt = FALSE;
2676 void (*oldsignal)(int);
2678 int start, end, sender_domain, recipient_domain;
2683 switch(smtp_read_command(TRUE))
2685 /* The AUTH command is not permitted to occur inside a transaction, and may
2686 occur successfully only once per connection. Actually, that isn't quite
2687 true. When TLS is started, all previous information about a connection must
2688 be discarded, so a new AUTH is permitted at that time.
2690 AUTH may only be used when it has been advertised. However, it seems that
2691 there are clients that send AUTH when it hasn't been advertised, some of
2692 them even doing this after HELO. And there are MTAs that accept this. Sigh.
2693 So there's a get-out that allows this to happen.
2695 AUTH is initially labelled as a "nonmail command" so that one occurrence
2696 doesn't get counted. We change the label here so that multiple failing
2697 AUTHS will eventually hit the nonmail threshold. */
2701 authentication_failed = TRUE;
2702 cmd_list[CMD_LIST_AUTH].is_mail_cmd = FALSE;
2704 if (!auth_advertised && !allow_auth_unadvertised)
2706 done = synprot_error(L_smtp_protocol_error, 503, NULL,
2707 US"AUTH command used when not advertised");
2710 if (sender_host_authenticated != NULL)
2712 done = synprot_error(L_smtp_protocol_error, 503, NULL,
2713 US"already authenticated");
2716 if (sender_address != NULL)
2718 done = synprot_error(L_smtp_protocol_error, 503, NULL,
2719 US"not permitted in mail transaction");
2725 if (acl_smtp_auth != NULL)
2727 rc = acl_check(ACL_WHERE_AUTH, NULL, acl_smtp_auth, &user_msg, &log_msg);
2730 done = smtp_handle_acl_fail(ACL_WHERE_AUTH, rc, user_msg, log_msg);
2735 /* Find the name of the requested authentication mechanism. */
2738 while ((c = *smtp_cmd_data) != 0 && !isspace(c))
2740 if (!isalnum(c) && c != '-' && c != '_')
2742 done = synprot_error(L_smtp_syntax_error, 501, NULL,
2743 US"invalid character in authentication mechanism name");
2749 /* If not at the end of the line, we must be at white space. Terminate the
2750 name and move the pointer on to any data that may be present. */
2752 if (*smtp_cmd_data != 0)
2754 *smtp_cmd_data++ = 0;
2755 while (isspace(*smtp_cmd_data)) smtp_cmd_data++;
2758 /* Search for an authentication mechanism which is configured for use
2759 as a server and which has been advertised (unless, sigh, allow_auth_
2760 unadvertised is set). */
2762 for (au = auths; au != NULL; au = au->next)
2764 if (strcmpic(s, au->public_name) == 0 && au->server &&
2765 (au->advertised || allow_auth_unadvertised)) break;
2770 done = synprot_error(L_smtp_protocol_error, 504, NULL,
2771 string_sprintf("%s authentication mechanism not supported", s));
2775 /* Run the checking code, passing the remainder of the command line as
2776 data. Initials the $auth<n> variables as empty. Initialize $0 empty and set
2777 it as the only set numerical variable. The authenticator may set $auth<n>
2778 and also set other numeric variables. The $auth<n> variables are preferred
2779 nowadays; the numerical variables remain for backwards compatibility.
2781 Afterwards, have a go at expanding the set_id string, even if
2782 authentication failed - for bad passwords it can be useful to log the
2783 userid. On success, require set_id to expand and exist, and put it in
2784 authenticated_id. Save this in permanent store, as the working store gets
2785 reset at HELO, RSET, etc. */
2787 for (i = 0; i < AUTH_VARS; i++) auth_vars[i] = NULL;
2789 expand_nlength[0] = 0; /* $0 contains nothing */
2791 c = (au->info->servercode)(au, smtp_cmd_data);
2792 if (au->set_id != NULL) set_id = expand_string(au->set_id);
2793 expand_nmax = -1; /* Reset numeric variables */
2794 for (i = 0; i < AUTH_VARS; i++) auth_vars[i] = NULL; /* Reset $auth<n> */
2796 /* The value of authenticated_id is stored in the spool file and printed in
2797 log lines. It must not contain binary zeros or newline characters. In
2798 normal use, it never will, but when playing around or testing, this error
2799 can (did) happen. To guard against this, ensure that the id contains only
2800 printing characters. */
2802 if (set_id != NULL) set_id = string_printing(set_id);
2804 /* For the non-OK cases, set up additional logging data if set_id
2809 if (set_id != NULL && *set_id != 0)
2810 set_id = string_sprintf(" (set_id=%s)", set_id);
2814 /* Switch on the result */
2819 if (au->set_id == NULL || set_id != NULL) /* Complete success */
2821 if (set_id != NULL) authenticated_id = string_copy_malloc(set_id);
2822 sender_host_authenticated = au->name;
2823 authentication_failed = FALSE;
2824 authenticated_fail_id = NULL; /* Impossible to already be set? */
2826 protocols[pextend + pauthed + ((tls_in.active >= 0)? pcrpted:0)] +
2827 ((sender_host_address != NULL)? pnlocal : 0);
2828 s = ss = US"235 Authentication succeeded";
2829 authenticated_by = au;
2833 /* Authentication succeeded, but we failed to expand the set_id string.
2834 Treat this as a temporary error. */
2836 auth_defer_msg = expand_string_message;
2840 if (set_id != NULL) authenticated_fail_id = string_copy_malloc(set_id);
2841 s = string_sprintf("435 Unable to authenticate at present%s",
2842 auth_defer_user_msg);
2843 ss = string_sprintf("435 Unable to authenticate at present%s: %s",
2844 set_id, auth_defer_msg);
2848 s = ss = US"501 Invalid base64 data";
2852 s = ss = US"501 Authentication cancelled";
2856 s = ss = US"553 Initial data not expected";
2860 if (set_id != NULL) authenticated_fail_id = string_copy_malloc(set_id);
2861 s = US"535 Incorrect authentication data";
2862 ss = string_sprintf("535 Incorrect authentication data%s", set_id);
2866 if (set_id != NULL) authenticated_fail_id = string_copy_malloc(set_id);
2867 s = US"435 Internal error";
2868 ss = string_sprintf("435 Internal error%s: return %d from authentication "
2869 "check", set_id, c);
2873 smtp_printf("%s\r\n", s);
2875 log_write(0, LOG_MAIN|LOG_REJECT, "%s authenticator failed for %s: %s",
2876 au->name, host_and_ident(FALSE), ss);
2878 break; /* AUTH_CMD */
2880 /* The HELO/EHLO commands are permitted to appear in the middle of a
2881 session as well as at the beginning. They have the effect of a reset in
2882 addition to their other functions. Their absence at the start cannot be
2883 taken to be an error.
2887 If the EHLO command is not acceptable to the SMTP server, 501, 500,
2888 or 502 failure replies MUST be returned as appropriate. The SMTP
2889 server MUST stay in the same state after transmitting these replies
2890 that it was in before the EHLO was received.
2892 Therefore, we do not do the reset until after checking the command for
2893 acceptability. This change was made for Exim release 4.11. Previously
2894 it did the reset first. */
2907 HELO_EHLO: /* Common code for HELO and EHLO */
2908 cmd_list[CMD_LIST_HELO].is_mail_cmd = FALSE;
2909 cmd_list[CMD_LIST_EHLO].is_mail_cmd = FALSE;
2911 /* Reject the HELO if its argument was invalid or non-existent. A
2912 successful check causes the argument to be saved in malloc store. */
2914 if (!check_helo(smtp_cmd_data))
2916 smtp_printf("501 Syntactically invalid %s argument(s)\r\n", hello);
2918 log_write(0, LOG_MAIN|LOG_REJECT, "rejected %s from %s: syntactically "
2919 "invalid argument(s): %s", hello, host_and_ident(FALSE),
2920 (*smtp_cmd_argument == 0)? US"(no argument given)" :
2921 string_printing(smtp_cmd_argument));
2923 if (++synprot_error_count > smtp_max_synprot_errors)
2925 log_write(0, LOG_MAIN|LOG_REJECT, "SMTP call from %s dropped: too many "
2926 "syntax or protocol errors (last command was \"%s\")",
2927 host_and_ident(FALSE), smtp_cmd_buffer);
2934 /* If sender_host_unknown is true, we have got here via the -bs interface,
2935 not called from inetd. Otherwise, we are running an IP connection and the
2936 host address will be set. If the helo name is the primary name of this
2937 host and we haven't done a reverse lookup, force one now. If helo_required
2938 is set, ensure that the HELO name matches the actual host. If helo_verify
2939 is set, do the same check, but softly. */
2941 if (!sender_host_unknown)
2943 BOOL old_helo_verified = helo_verified;
2944 uschar *p = smtp_cmd_data;
2946 while (*p != 0 && !isspace(*p)) { *p = tolower(*p); p++; }
2949 /* Force a reverse lookup if HELO quoted something in helo_lookup_domains
2950 because otherwise the log can be confusing. */
2952 if (sender_host_name == NULL &&
2953 (deliver_domain = sender_helo_name, /* set $domain */
2954 match_isinlist(sender_helo_name, &helo_lookup_domains, 0,
2955 &domainlist_anchor, NULL, MCL_DOMAIN, TRUE, NULL)) == OK)
2956 (void)host_name_lookup();
2958 /* Rebuild the fullhost info to include the HELO name (and the real name
2959 if it was looked up.) */
2961 host_build_sender_fullhost(); /* Rebuild */
2962 set_process_info("handling%s incoming connection from %s",
2963 (tls_in.active >= 0)? " TLS" : "", host_and_ident(FALSE));
2965 /* Verify if configured. This doesn't give much security, but it does
2966 make some people happy to be able to do it. If helo_required is set,
2967 (host matches helo_verify_hosts) failure forces rejection. If helo_verify
2968 is set (host matches helo_try_verify_hosts), it does not. This is perhaps
2969 now obsolescent, since the verification can now be requested selectively
2972 helo_verified = helo_verify_failed = FALSE;
2973 if (helo_required || helo_verify)
2975 BOOL tempfail = !smtp_verify_helo();
2980 smtp_printf("%d %s argument does not match calling host\r\n",
2981 tempfail? 451 : 550, hello);
2982 log_write(0, LOG_MAIN|LOG_REJECT, "%srejected \"%s %s\" from %s",
2983 tempfail? "temporarily " : "",
2984 hello, sender_helo_name, host_and_ident(FALSE));
2985 helo_verified = old_helo_verified;
2986 break; /* End of HELO/EHLO processing */
2988 HDEBUG(D_all) debug_printf("%s verification failed but host is in "
2989 "helo_try_verify_hosts\n", hello);
2994 #ifdef EXPERIMENTAL_SPF
2995 /* set up SPF context */
2996 spf_init(sender_helo_name, sender_host_address);
2999 /* Apply an ACL check if one is defined; afterwards, recheck
3000 synchronization in case the client started sending in a delay. */
3002 if (acl_smtp_helo != NULL)
3004 rc = acl_check(ACL_WHERE_HELO, NULL, acl_smtp_helo, &user_msg, &log_msg);
3007 done = smtp_handle_acl_fail(ACL_WHERE_HELO, rc, user_msg, log_msg);
3008 sender_helo_name = NULL;
3009 host_build_sender_fullhost(); /* Rebuild */
3012 else if (!check_sync()) goto SYNC_FAILURE;
3015 /* Generate an OK reply. The default string includes the ident if present,
3016 and also the IP address if present. Reflecting back the ident is intended
3017 as a deterrent to mail forgers. For maximum efficiency, and also because
3018 some broken systems expect each response to be in a single packet, arrange
3019 that the entire reply is sent in one write(). */
3021 auth_advertised = FALSE;
3022 pipelining_advertised = FALSE;
3024 tls_advertised = FALSE;
3027 smtp_code = US"250 "; /* Default response code plus space*/
3028 if (user_msg == NULL)
3030 s = string_sprintf("%.3s %s Hello %s%s%s",
3032 smtp_active_hostname,
3033 (sender_ident == NULL)? US"" : sender_ident,
3034 (sender_ident == NULL)? US"" : US" at ",
3035 (sender_host_name == NULL)? sender_helo_name : sender_host_name);
3040 if (sender_host_address != NULL)
3042 s = string_cat(s, &size, &ptr, US" [", 2);
3043 s = string_cat(s, &size, &ptr, sender_host_address,
3044 Ustrlen(sender_host_address));
3045 s = string_cat(s, &size, &ptr, US"]", 1);
3049 /* A user-supplied EHLO greeting may not contain more than one line. Note
3050 that the code returned by smtp_message_code() includes the terminating
3051 whitespace character. */
3057 smtp_message_code(&smtp_code, &codelen, &user_msg, NULL);
3058 s = string_sprintf("%.*s%s", codelen, smtp_code, user_msg);
3059 if ((ss = strpbrk(CS s, "\r\n")) != NULL)
3061 log_write(0, LOG_MAIN|LOG_PANIC, "EHLO/HELO response must not contain "
3062 "newlines: message truncated: %s", string_printing(s));
3069 s = string_cat(s, &size, &ptr, US"\r\n", 2);
3071 /* If we received EHLO, we must create a multiline response which includes
3072 the functions supported. */
3078 /* I'm not entirely happy with this, as an MTA is supposed to check
3079 that it has enough room to accept a message of maximum size before
3080 it sends this. However, there seems little point in not sending it.
3081 The actual size check happens later at MAIL FROM time. By postponing it
3082 till then, VRFY and EXPN can be used after EHLO when space is short. */
3084 if (thismessage_size_limit > 0)
3086 sprintf(CS big_buffer, "%.3s-SIZE %d\r\n", smtp_code,
3087 thismessage_size_limit);
3088 s = string_cat(s, &size, &ptr, big_buffer, Ustrlen(big_buffer));
3092 s = string_cat(s, &size, &ptr, smtp_code, 3);
3093 s = string_cat(s, &size, &ptr, US"-SIZE\r\n", 7);
3096 /* Exim does not do protocol conversion or data conversion. It is 8-bit
3097 clean; if it has an 8-bit character in its hand, it just sends it. It
3098 cannot therefore specify 8BITMIME and remain consistent with the RFCs.
3099 However, some users want this option simply in order to stop MUAs
3100 mangling messages that contain top-bit-set characters. It is therefore
3101 provided as an option. */
3103 if (accept_8bitmime)
3105 s = string_cat(s, &size, &ptr, smtp_code, 3);
3106 s = string_cat(s, &size, &ptr, US"-8BITMIME\r\n", 11);
3109 /* Advertise ETRN if there's an ACL checking whether a host is
3110 permitted to issue it; a check is made when any host actually tries. */
3112 if (acl_smtp_etrn != NULL)
3114 s = string_cat(s, &size, &ptr, smtp_code, 3);
3115 s = string_cat(s, &size, &ptr, US"-ETRN\r\n", 7);
3118 /* Advertise EXPN if there's an ACL checking whether a host is
3119 permitted to issue it; a check is made when any host actually tries. */
3121 if (acl_smtp_expn != NULL)
3123 s = string_cat(s, &size, &ptr, smtp_code, 3);
3124 s = string_cat(s, &size, &ptr, US"-EXPN\r\n", 7);
3127 /* Exim is quite happy with pipelining, so let the other end know that
3128 it is safe to use it, unless advertising is disabled. */
3130 if (pipelining_enable &&
3131 verify_check_host(&pipelining_advertise_hosts) == OK)
3133 s = string_cat(s, &size, &ptr, smtp_code, 3);
3134 s = string_cat(s, &size, &ptr, US"-PIPELINING\r\n", 13);
3135 sync_cmd_limit = NON_SYNC_CMD_PIPELINING;
3136 pipelining_advertised = TRUE;
3140 /* If any server authentication mechanisms are configured, advertise
3141 them if the current host is in auth_advertise_hosts. The problem with
3142 advertising always is that some clients then require users to
3143 authenticate (and aren't configurable otherwise) even though it may not
3144 be necessary (e.g. if the host is in host_accept_relay).
3146 RFC 2222 states that SASL mechanism names contain only upper case
3147 letters, so output the names in upper case, though we actually recognize
3148 them in either case in the AUTH command. */
3152 if (verify_check_host(&auth_advertise_hosts) == OK)
3156 for (au = auths; au != NULL; au = au->next)
3158 if (au->server && (au->advertise_condition == NULL ||
3159 expand_check_condition(au->advertise_condition, au->name,
3160 US"authenticator")))
3165 s = string_cat(s, &size, &ptr, smtp_code, 3);
3166 s = string_cat(s, &size, &ptr, US"-AUTH", 5);
3168 auth_advertised = TRUE;
3171 s = string_cat(s, &size, &ptr, US" ", 1);
3172 s = string_cat(s, &size, &ptr, au->public_name,
3173 Ustrlen(au->public_name));
3174 while (++saveptr < ptr) s[saveptr] = toupper(s[saveptr]);
3175 au->advertised = TRUE;
3177 else au->advertised = FALSE;
3179 if (!first) s = string_cat(s, &size, &ptr, US"\r\n", 2);
3183 /* Advertise TLS (Transport Level Security) aka SSL (Secure Socket Layer)
3184 if it has been included in the binary, and the host matches
3185 tls_advertise_hosts. We must *not* advertise if we are already in a
3186 secure connection. */
3189 if (tls_in.active < 0 &&
3190 verify_check_host(&tls_advertise_hosts) != FAIL)
3192 s = string_cat(s, &size, &ptr, smtp_code, 3);
3193 s = string_cat(s, &size, &ptr, US"-STARTTLS\r\n", 11);
3194 tls_advertised = TRUE;
3198 #ifdef EXPERIMENTAL_PRDR
3199 /* Per Recipient Data Response, draft by Eric A. Hall extending RFC */
3201 s = string_cat(s, &size, &ptr, smtp_code, 3);
3202 s = string_cat(s, &size, &ptr, US"-PRDR\r\n", 7);
3206 /* Finish off the multiline reply with one that is always available. */
3208 s = string_cat(s, &size, &ptr, smtp_code, 3);
3209 s = string_cat(s, &size, &ptr, US" HELP\r\n", 7);
3212 /* Terminate the string (for debug), write it, and note that HELO/EHLO
3218 if (tls_in.active >= 0) (void)tls_write(TRUE, s, ptr); else
3222 int i = fwrite(s, 1, ptr, smtp_out); i = i; /* compiler quietening */
3227 while ((cr = Ustrchr(s, '\r')) != NULL) /* lose CRs */
3228 memmove(cr, cr + 1, (ptr--) - (cr - s));
3229 debug_printf("SMTP>> %s", s);
3233 /* Reset the protocol and the state, abandoning any previous message. */
3235 received_protocol = (esmtp?
3237 ((sender_host_authenticated != NULL)? pauthed : 0) +
3238 ((tls_in.active >= 0)? pcrpted : 0)]
3240 protocols[pnormal + ((tls_in.active >= 0)? pcrpted : 0)])
3242 ((sender_host_address != NULL)? pnlocal : 0);
3244 smtp_reset(reset_point);
3246 break; /* HELO/EHLO */
3249 /* The MAIL command requires an address as an operand. All we do
3250 here is to parse it for syntactic correctness. The form "<>" is
3251 a special case which converts into an empty string. The start/end
3252 pointers in the original are not used further for this address, as
3253 it is the canonical extracted address which is all that is kept. */
3257 smtp_mailcmd_count++; /* Count for limit and ratelimit */
3258 was_rej_mail = TRUE; /* Reset if accepted */
3259 env_mail_type_t * mail_args; /* Sanity check & validate args */
3261 if (helo_required && !helo_seen)
3263 smtp_printf("503 HELO or EHLO required\r\n");
3264 log_write(0, LOG_MAIN|LOG_REJECT, "rejected MAIL from %s: no "
3265 "HELO/EHLO given", host_and_ident(FALSE));
3269 if (sender_address != NULL)
3271 done = synprot_error(L_smtp_protocol_error, 503, NULL,
3272 US"sender already given");
3276 if (smtp_cmd_data[0] == 0)
3278 done = synprot_error(L_smtp_protocol_error, 501, NULL,
3279 US"MAIL must have an address operand");
3283 /* Check to see if the limit for messages per connection would be
3284 exceeded by accepting further messages. */
3286 if (smtp_accept_max_per_connection > 0 &&
3287 smtp_mailcmd_count > smtp_accept_max_per_connection)
3289 smtp_printf("421 too many messages in this connection\r\n");
3290 log_write(0, LOG_MAIN|LOG_REJECT, "rejected MAIL command %s: too many "
3291 "messages in one connection", host_and_ident(TRUE));
3295 /* Reset for start of message - even if this is going to fail, we
3296 obviously need to throw away any previous data. */
3298 smtp_reset(reset_point);
3300 sender_data = recipient_data = NULL;
3302 /* Loop, checking for ESMTP additions to the MAIL FROM command. */
3306 uschar *name, *value, *end;
3307 unsigned long int size;
3308 BOOL arg_error = FALSE;
3310 if (!extract_option(&name, &value)) break;
3312 for (mail_args = env_mail_type_list;
3313 (char *)mail_args < (char *)env_mail_type_list + sizeof(env_mail_type_list);
3317 if (strcmpic(name, mail_args->name) == 0)
3320 if (mail_args->need_value && strcmpic(value, US"") == 0)
3323 switch(mail_args->value)
3325 /* Handle SIZE= by reading the value. We don't do the check till later,
3326 in order to be able to log the sender address on failure. */
3327 case ENV_MAIL_OPT_SIZE:
3328 if (((size = Ustrtoul(value, &end, 10)), *end == 0))
3330 if ((size == ULONG_MAX && errno == ERANGE) || size > INT_MAX)
3332 message_size = (int)size;
3338 /* If this session was initiated with EHLO and accept_8bitmime is set,
3339 Exim will have indicated that it supports the BODY=8BITMIME option. In
3340 fact, it does not support this according to the RFCs, in that it does not
3341 take any special action for forwarding messages containing 8-bit
3342 characters. That is why accept_8bitmime is not the default setting, but
3343 some sites want the action that is provided. We recognize both "8BITMIME"
3344 and "7BIT" as body types, but take no action. */
3345 case ENV_MAIL_OPT_BODY:
3346 if (accept_8bitmime) {
3347 if (strcmpic(value, US"8BITMIME") == 0) {
3349 } else if (strcmpic(value, US"7BIT") == 0) {
3353 done = synprot_error(L_smtp_syntax_error, 501, NULL,
3354 US"invalid data for BODY");
3357 DEBUG(D_receive) debug_printf("8BITMIME: %d\n", body_8bitmime);
3363 /* Handle the AUTH extension. If the value given is not "<>" and either
3364 the ACL says "yes" or there is no ACL but the sending host is
3365 authenticated, we set it up as the authenticated sender. However, if the
3366 authenticator set a condition to be tested, we ignore AUTH on MAIL unless
3367 the condition is met. The value of AUTH is an xtext, which means that +,
3368 = and cntrl chars are coded in hex; however "<>" is unaffected by this
3370 case ENV_MAIL_OPT_AUTH:
3371 if (Ustrcmp(value, "<>") != 0)
3376 if (auth_xtextdecode(value, &authenticated_sender) < 0)
3378 /* Put back terminator overrides for error message */
3381 done = synprot_error(L_smtp_syntax_error, 501, NULL,
3382 US"invalid data for AUTH");
3385 if (acl_smtp_mailauth == NULL)
3387 ignore_msg = US"client not authenticated";
3388 rc = (sender_host_authenticated != NULL)? OK : FAIL;
3392 ignore_msg = US"rejected by ACL";
3393 rc = acl_check(ACL_WHERE_MAILAUTH, NULL, acl_smtp_mailauth,
3394 &user_msg, &log_msg);
3400 if (authenticated_by == NULL ||
3401 authenticated_by->mail_auth_condition == NULL ||
3402 expand_check_condition(authenticated_by->mail_auth_condition,
3403 authenticated_by->name, US"authenticator"))
3404 break; /* Accept the AUTH */
3406 ignore_msg = US"server_mail_auth_condition failed";
3407 if (authenticated_id != NULL)
3408 ignore_msg = string_sprintf("%s: authenticated ID=\"%s\"",
3409 ignore_msg, authenticated_id);
3414 authenticated_sender = NULL;
3415 log_write(0, LOG_MAIN, "ignoring AUTH=%s from %s (%s)",
3416 value, host_and_ident(TRUE), ignore_msg);
3419 /* Should only get DEFER or ERROR here. Put back terminator
3420 overrides for error message */
3425 (void)smtp_handle_acl_fail(ACL_WHERE_MAILAUTH, rc, user_msg,
3432 #ifdef EXPERIMENTAL_PRDR
3433 case ENV_MAIL_OPT_PRDR:
3435 prdr_requested = TRUE;
3439 /* Unknown option. Stick back the terminator characters and break
3440 the loop. Do the name-terminator second as extract_option sets
3441 value==name when it found no equal-sign.
3442 An error for a malformed address will occur. */
3449 /* Break out of for loop if switch() had bad argument or
3450 when start of the email address is reached */
3451 if (arg_error) break;
3454 /* If we have passed the threshold for rate limiting, apply the current
3455 delay, and update it for next time, provided this is a limited host. */
3457 if (smtp_mailcmd_count > smtp_rlm_threshold &&
3458 verify_check_host(&smtp_ratelimit_hosts) == OK)
3460 DEBUG(D_receive) debug_printf("rate limit MAIL: delay %.3g sec\n",
3461 smtp_delay_mail/1000.0);
3462 millisleep((int)smtp_delay_mail);
3463 smtp_delay_mail *= smtp_rlm_factor;
3464 if (smtp_delay_mail > (double)smtp_rlm_limit)
3465 smtp_delay_mail = (double)smtp_rlm_limit;
3468 /* Now extract the address, first applying any SMTP-time rewriting. The
3469 TRUE flag allows "<>" as a sender address. */
3471 raw_sender = ((rewrite_existflags & rewrite_smtp) != 0)?
3472 rewrite_one(smtp_cmd_data, rewrite_smtp, NULL, FALSE, US"",
3473 global_rewrite_rules) : smtp_cmd_data;
3475 /* rfc821_domains = TRUE; << no longer needed */
3477 parse_extract_address(raw_sender, &errmess, &start, &end, &sender_domain,
3479 /* rfc821_domains = FALSE; << no longer needed */
3481 if (raw_sender == NULL)
3483 done = synprot_error(L_smtp_syntax_error, 501, smtp_cmd_data, errmess);
3487 sender_address = raw_sender;
3489 /* If there is a configured size limit for mail, check that this message
3490 doesn't exceed it. The check is postponed to this point so that the sender
3493 if (thismessage_size_limit > 0 && message_size > thismessage_size_limit)
3495 smtp_printf("552 Message size exceeds maximum permitted\r\n");
3496 log_write(L_size_reject,
3497 LOG_MAIN|LOG_REJECT, "rejected MAIL FROM:<%s> %s: "
3498 "message too big: size%s=%d max=%d",
3500 host_and_ident(TRUE),
3501 (message_size == INT_MAX)? ">" : "",
3503 thismessage_size_limit);
3504 sender_address = NULL;
3508 /* Check there is enough space on the disk unless configured not to.
3509 When smtp_check_spool_space is set, the check is for thismessage_size_limit
3510 plus the current message - i.e. we accept the message only if it won't
3511 reduce the space below the threshold. Add 5000 to the size to allow for
3512 overheads such as the Received: line and storing of recipients, etc.
3513 By putting the check here, even when SIZE is not given, it allow VRFY
3514 and EXPN etc. to be used when space is short. */
3516 if (!receive_check_fs(
3517 (smtp_check_spool_space && message_size >= 0)?
3518 message_size + 5000 : 0))
3520 smtp_printf("452 Space shortage, please try later\r\n");
3521 sender_address = NULL;
3525 /* If sender_address is unqualified, reject it, unless this is a locally
3526 generated message, or the sending host or net is permitted to send
3527 unqualified addresses - typically local machines behaving as MUAs -
3528 in which case just qualify the address. The flag is set above at the start
3529 of the SMTP connection. */
3531 if (sender_domain == 0 && sender_address[0] != 0)
3533 if (allow_unqualified_sender)
3535 sender_domain = Ustrlen(sender_address) + 1;
3536 sender_address = rewrite_address_qualify(sender_address, FALSE);
3537 DEBUG(D_receive) debug_printf("unqualified address %s accepted\n",
3542 smtp_printf("501 %s: sender address must contain a domain\r\n",
3544 log_write(L_smtp_syntax_error,
3545 LOG_MAIN|LOG_REJECT,
3546 "unqualified sender rejected: <%s> %s%s",
3548 host_and_ident(TRUE),
3550 sender_address = NULL;
3555 /* Apply an ACL check if one is defined, before responding. Afterwards,
3556 when pipelining is not advertised, do another sync check in case the ACL
3557 delayed and the client started sending in the meantime. */
3559 if (acl_smtp_mail == NULL) rc = OK; else
3561 rc = acl_check(ACL_WHERE_MAIL, NULL, acl_smtp_mail, &user_msg, &log_msg);
3562 if (rc == OK && !pipelining_advertised && !check_sync())
3566 if (rc == OK || rc == DISCARD)
3568 if (user_msg == NULL)
3569 smtp_printf("%s%s%s", US"250 OK",
3570 #ifdef EXPERIMENTAL_PRDR
3571 prdr_requested == TRUE ? US", PRDR Requested" :
3577 #ifdef EXPERIMENTAL_PRDR
3578 if ( prdr_requested == TRUE )
3579 user_msg = string_sprintf("%s%s", user_msg, US", PRDR Requested");
3581 smtp_user_msg(US"250",user_msg);
3583 smtp_delay_rcpt = smtp_rlr_base;
3584 recipients_discarded = (rc == DISCARD);
3585 was_rej_mail = FALSE;
3589 done = smtp_handle_acl_fail(ACL_WHERE_MAIL, rc, user_msg, log_msg);
3590 sender_address = NULL;
3595 /* The RCPT command requires an address as an operand. There may be any
3596 number of RCPT commands, specifying multiple recipients. We build them all
3597 into a data structure. The start/end values given by parse_extract_address
3598 are not used, as we keep only the extracted address. */
3603 was_rcpt = rcpt_in_progress = TRUE;
3605 /* There must be a sender address; if the sender was rejected and
3606 pipelining was advertised, we assume the client was pipelining, and do not
3607 count this as a protocol error. Reset was_rej_mail so that further RCPTs
3608 get the same treatment. */
3610 if (sender_address == NULL)
3612 if (pipelining_advertised && last_was_rej_mail)
3614 smtp_printf("503 sender not yet given\r\n");
3615 was_rej_mail = TRUE;
3619 done = synprot_error(L_smtp_protocol_error, 503, NULL,
3620 US"sender not yet given");
3621 was_rcpt = FALSE; /* Not a valid RCPT */
3627 /* Check for an operand */
3629 if (smtp_cmd_data[0] == 0)
3631 done = synprot_error(L_smtp_syntax_error, 501, NULL,
3632 US"RCPT must have an address operand");
3637 /* Apply SMTP rewriting then extract the working address. Don't allow "<>"
3638 as a recipient address */
3640 recipient = ((rewrite_existflags & rewrite_smtp) != 0)?
3641 rewrite_one(smtp_cmd_data, rewrite_smtp, NULL, FALSE, US"",
3642 global_rewrite_rules) : smtp_cmd_data;
3644 /* rfc821_domains = TRUE; << no longer needed */
3645 recipient = parse_extract_address(recipient, &errmess, &start, &end,
3646 &recipient_domain, FALSE);
3647 /* rfc821_domains = FALSE; << no longer needed */
3649 if (recipient == NULL)
3651 done = synprot_error(L_smtp_syntax_error, 501, smtp_cmd_data, errmess);
3656 /* If the recipient address is unqualified, reject it, unless this is a
3657 locally generated message. However, unqualified addresses are permitted
3658 from a configured list of hosts and nets - typically when behaving as
3659 MUAs rather than MTAs. Sad that SMTP is used for both types of traffic,
3660 really. The flag is set at the start of the SMTP connection.
3662 RFC 1123 talks about supporting "the reserved mailbox postmaster"; I always
3663 assumed this meant "reserved local part", but the revision of RFC 821 and
3664 friends now makes it absolutely clear that it means *mailbox*. Consequently
3665 we must always qualify this address, regardless. */
3667 if (recipient_domain == 0)
3669 if (allow_unqualified_recipient ||
3670 strcmpic(recipient, US"postmaster") == 0)
3672 DEBUG(D_receive) debug_printf("unqualified address %s accepted\n",
3674 recipient_domain = Ustrlen(recipient) + 1;
3675 recipient = rewrite_address_qualify(recipient, TRUE);
3680 smtp_printf("501 %s: recipient address must contain a domain\r\n",
3682 log_write(L_smtp_syntax_error,
3683 LOG_MAIN|LOG_REJECT, "unqualified recipient rejected: "
3684 "<%s> %s%s", recipient, host_and_ident(TRUE),
3690 /* Check maximum allowed */
3692 if (rcpt_count > recipients_max && recipients_max > 0)
3694 if (recipients_max_reject)
3697 smtp_printf("552 too many recipients\r\n");
3699 log_write(0, LOG_MAIN|LOG_REJECT, "too many recipients: message "
3700 "rejected: sender=<%s> %s", sender_address, host_and_ident(TRUE));
3705 smtp_printf("452 too many recipients\r\n");
3707 log_write(0, LOG_MAIN|LOG_REJECT, "too many recipients: excess "
3708 "temporarily rejected: sender=<%s> %s", sender_address,
3709 host_and_ident(TRUE));
3716 /* If we have passed the threshold for rate limiting, apply the current
3717 delay, and update it for next time, provided this is a limited host. */
3719 if (rcpt_count > smtp_rlr_threshold &&
3720 verify_check_host(&smtp_ratelimit_hosts) == OK)
3722 DEBUG(D_receive) debug_printf("rate limit RCPT: delay %.3g sec\n",
3723 smtp_delay_rcpt/1000.0);
3724 millisleep((int)smtp_delay_rcpt);
3725 smtp_delay_rcpt *= smtp_rlr_factor;
3726 if (smtp_delay_rcpt > (double)smtp_rlr_limit)
3727 smtp_delay_rcpt = (double)smtp_rlr_limit;
3730 /* If the MAIL ACL discarded all the recipients, we bypass ACL checking
3731 for them. Otherwise, check the access control list for this recipient. As
3732 there may be a delay in this, re-check for a synchronization error
3733 afterwards, unless pipelining was advertised. */
3735 if (recipients_discarded) rc = DISCARD; else
3737 rc = acl_check(ACL_WHERE_RCPT, recipient, acl_smtp_rcpt, &user_msg,
3739 if (rc == OK && !pipelining_advertised && !check_sync())
3743 /* The ACL was happy */
3747 if (user_msg == NULL) smtp_printf("250 Accepted\r\n");
3748 else smtp_user_msg(US"250", user_msg);
3749 receive_add_recipient(recipient, -1);
3752 /* The recipient was discarded */
3754 else if (rc == DISCARD)
3756 if (user_msg == NULL) smtp_printf("250 Accepted\r\n");
3757 else smtp_user_msg(US"250", user_msg);
3760 log_write(0, LOG_MAIN|LOG_REJECT, "%s F=<%s> rejected RCPT %s: "
3761 "discarded by %s ACL%s%s", host_and_ident(TRUE),
3762 (sender_address_unrewritten != NULL)?
3763 sender_address_unrewritten : sender_address,
3764 smtp_cmd_argument, recipients_discarded? "MAIL" : "RCPT",
3765 (log_msg == NULL)? US"" : US": ",
3766 (log_msg == NULL)? US"" : log_msg);
3769 /* Either the ACL failed the address, or it was deferred. */
3773 if (rc == FAIL) rcpt_fail_count++; else rcpt_defer_count++;
3774 done = smtp_handle_acl_fail(ACL_WHERE_RCPT, rc, user_msg, log_msg);
3779 /* The DATA command is legal only if it follows successful MAIL FROM
3780 and RCPT TO commands. However, if pipelining is advertised, a bad DATA is
3781 not counted as a protocol error if it follows RCPT (which must have been
3782 rejected if there are no recipients.) This function is complete when a
3783 valid DATA command is encountered.
3785 Note concerning the code used: RFC 2821 says this:
3787 - If there was no MAIL, or no RCPT, command, or all such commands
3788 were rejected, the server MAY return a "command out of sequence"
3789 (503) or "no valid recipients" (554) reply in response to the
3792 The example in the pipelining RFC 2920 uses 554, but I use 503 here
3793 because it is the same whether pipelining is in use or not.
3795 If all the RCPT commands that precede DATA provoked the same error message
3796 (often indicating some kind of system error), it is helpful to include it
3797 with the DATA rejection (an idea suggested by Tony Finch). */
3801 if (!discarded && recipients_count <= 0)
3803 if (rcpt_smtp_response_same && rcpt_smtp_response != NULL)
3805 uschar *code = US"503";
3806 int len = Ustrlen(rcpt_smtp_response);
3807 smtp_respond(code, 3, FALSE, US"All RCPT commands were rejected with "
3809 /* Responses from smtp_printf() will have \r\n on the end */
3810 if (len > 2 && rcpt_smtp_response[len-2] == '\r')
3811 rcpt_smtp_response[len-2] = 0;
3812 smtp_respond(code, 3, FALSE, rcpt_smtp_response);
3814 if (pipelining_advertised && last_was_rcpt)
3815 smtp_printf("503 Valid RCPT command must precede DATA\r\n");
3817 done = synprot_error(L_smtp_protocol_error, 503, NULL,
3818 US"valid RCPT command must precede DATA");
3822 if (toomany && recipients_max_reject)
3824 sender_address = NULL; /* This will allow a new MAIL without RSET */
3825 sender_address_unrewritten = NULL;
3826 smtp_printf("554 Too many recipients\r\n");
3830 /* If there is an ACL, re-check the synchronization afterwards, since the
3831 ACL may have delayed. To handle cutthrough delivery enforce a dummy call
3832 to get the DATA command sent. */
3834 if (acl_smtp_predata == NULL && cutthrough_fd < 0) rc = OK; else
3836 uschar * acl= acl_smtp_predata ? acl_smtp_predata : US"accept";
3837 enable_dollar_recipients = TRUE;
3838 rc = acl_check(ACL_WHERE_PREDATA, NULL, acl, &user_msg,
3840 enable_dollar_recipients = FALSE;
3841 if (rc == OK && !check_sync()) goto SYNC_FAILURE;
3848 if (user_msg == NULL)
3849 smtp_printf("%s Enter message, ending with \".\" on a line by itself\r\n", code);
3850 else smtp_user_msg(code, user_msg);
3852 message_ended = END_NOTENDED; /* Indicate in middle of data */
3855 /* Either the ACL failed the address, or it was deferred. */
3858 done = smtp_handle_acl_fail(ACL_WHERE_PREDATA, rc, user_msg, log_msg);
3864 rc = acl_check(ACL_WHERE_VRFY, NULL, acl_smtp_vrfy, &user_msg, &log_msg);
3866 done = smtp_handle_acl_fail(ACL_WHERE_VRFY, rc, user_msg, log_msg);
3872 /* rfc821_domains = TRUE; << no longer needed */
3873 address = parse_extract_address(smtp_cmd_data, &errmess, &start, &end,
3874 &recipient_domain, FALSE);
3875 /* rfc821_domains = FALSE; << no longer needed */
3877 if (address == NULL)
3878 s = string_sprintf("501 %s", errmess);
3881 address_item *addr = deliver_make_addr(address, FALSE);
3882 switch(verify_address(addr, NULL, vopt_is_recipient | vopt_qualify, -1,
3883 -1, -1, NULL, NULL, NULL))
3886 s = string_sprintf("250 <%s> is deliverable", address);
3890 s = (addr->user_message != NULL)?
3891 string_sprintf("451 <%s> %s", address, addr->user_message) :
3892 string_sprintf("451 Cannot resolve <%s> at this time", address);
3896 s = (addr->user_message != NULL)?
3897 string_sprintf("550 <%s> %s", address, addr->user_message) :
3898 string_sprintf("550 <%s> is not deliverable", address);
3899 log_write(0, LOG_MAIN, "VRFY failed for %s %s",
3900 smtp_cmd_argument, host_and_ident(TRUE));
3905 smtp_printf("%s\r\n", s);
3912 rc = acl_check(ACL_WHERE_EXPN, NULL, acl_smtp_expn, &user_msg, &log_msg);
3914 done = smtp_handle_acl_fail(ACL_WHERE_EXPN, rc, user_msg, log_msg);
3917 BOOL save_log_testing_mode = log_testing_mode;
3918 address_test_mode = log_testing_mode = TRUE;
3919 (void) verify_address(deliver_make_addr(smtp_cmd_data, FALSE),
3920 smtp_out, vopt_is_recipient | vopt_qualify | vopt_expn, -1, -1, -1,
3922 address_test_mode = FALSE;
3923 log_testing_mode = save_log_testing_mode; /* true for -bh */
3932 if (!tls_advertised)
3934 done = synprot_error(L_smtp_protocol_error, 503, NULL,
3935 US"STARTTLS command used when not advertised");
3939 /* Apply an ACL check if one is defined */
3941 if (acl_smtp_starttls != NULL)
3943 rc = acl_check(ACL_WHERE_STARTTLS, NULL, acl_smtp_starttls, &user_msg,
3947 done = smtp_handle_acl_fail(ACL_WHERE_STARTTLS, rc, user_msg, log_msg);
3952 /* RFC 2487 is not clear on when this command may be sent, though it
3953 does state that all information previously obtained from the client
3954 must be discarded if a TLS session is started. It seems reasonble to
3955 do an implied RSET when STARTTLS is received. */
3957 incomplete_transaction_log(US"STARTTLS");
3958 smtp_reset(reset_point);
3960 cmd_list[CMD_LIST_STARTTLS].is_mail_cmd = FALSE;
3962 /* There's an attack where more data is read in past the STARTTLS command
3963 before TLS is negotiated, then assumed to be part of the secure session
3964 when used afterwards; we use segregated input buffers, so are not
3965 vulnerable, but we want to note when it happens and, for sheer paranoia,
3966 ensure that the buffer is "wiped".
3967 Pipelining sync checks will normally have protected us too, unless disabled
3968 by configuration. */
3970 if (receive_smtp_buffered())
3973 debug_printf("Non-empty input buffer after STARTTLS; naive attack?");
3974 if (tls_in.active < 0)
3975 smtp_inend = smtp_inptr = smtp_inbuffer;
3976 /* and if TLS is already active, tls_server_start() should fail */
3979 /* There is nothing we value in the input buffer and if TLS is succesfully
3980 negotiated, we won't use this buffer again; if TLS fails, we'll just read
3981 fresh content into it. The buffer contains arbitrary content from an
3982 untrusted remote source; eg: NOOP <shellcode>\r\nSTARTTLS\r\n
3983 It seems safest to just wipe away the content rather than leave it as a
3984 target to jump to. */
3986 memset(smtp_inbuffer, 0, in_buffer_size);
3988 /* Attempt to start up a TLS session, and if successful, discard all
3989 knowledge that was obtained previously. At least, that's what the RFC says,
3990 and that's what happens by default. However, in order to work round YAEB,
3991 there is an option to remember the esmtp state. Sigh.
3993 We must allow for an extra EHLO command and an extra AUTH command after
3994 STARTTLS that don't add to the nonmail command count. */
3996 if ((rc = tls_server_start(tls_require_ciphers)) == OK)
3998 if (!tls_remember_esmtp)
3999 helo_seen = esmtp = auth_advertised = pipelining_advertised = FALSE;
4000 cmd_list[CMD_LIST_EHLO].is_mail_cmd = TRUE;
4001 cmd_list[CMD_LIST_AUTH].is_mail_cmd = TRUE;
4002 if (sender_helo_name != NULL)
4004 store_free(sender_helo_name);
4005 sender_helo_name = NULL;
4006 host_build_sender_fullhost(); /* Rebuild */
4007 set_process_info("handling incoming TLS connection from %s",
4008 host_and_ident(FALSE));
4010 received_protocol = (esmtp?
4011 protocols[pextend + pcrpted +
4012 ((sender_host_authenticated != NULL)? pauthed : 0)]
4014 protocols[pnormal + pcrpted])
4016 ((sender_host_address != NULL)? pnlocal : 0);
4018 sender_host_authenticated = NULL;
4019 authenticated_id = NULL;
4020 sync_cmd_limit = NON_SYNC_CMD_NON_PIPELINING;
4021 DEBUG(D_tls) debug_printf("TLS active\n");
4022 break; /* Successful STARTTLS */
4025 /* Some local configuration problem was discovered before actually trying
4026 to do a TLS handshake; give a temporary error. */
4028 else if (rc == DEFER)
4030 smtp_printf("454 TLS currently unavailable\r\n");
4034 /* Hard failure. Reject everything except QUIT or closed connection. One
4035 cause for failure is a nested STARTTLS, in which case tls_in.active remains
4036 set, but we must still reject all incoming commands. */
4038 DEBUG(D_tls) debug_printf("TLS failed to start\n");
4041 switch(smtp_read_command(FALSE))
4044 log_write(L_smtp_connection, LOG_MAIN, "%s closed by EOF",
4045 smtp_get_connection_info());
4046 smtp_notquit_exit(US"tls-failed", NULL, NULL);
4050 /* It is perhaps arguable as to which exit ACL should be called here,
4051 but as it is probably a situation that almost never arises, it
4052 probably doesn't matter. We choose to call the real QUIT ACL, which in
4053 some sense is perhaps "right". */
4057 if (acl_smtp_quit != NULL)
4059 rc = acl_check(ACL_WHERE_QUIT, NULL, acl_smtp_quit, &user_msg,
4062 log_write(0, LOG_MAIN|LOG_PANIC, "ACL for QUIT returned ERROR: %s",
4065 if (user_msg == NULL)
4066 smtp_printf("221 %s closing connection\r\n", smtp_active_hostname);
4068 smtp_respond(US"221", 3, TRUE, user_msg);
4069 log_write(L_smtp_connection, LOG_MAIN, "%s closed by QUIT",
4070 smtp_get_connection_info());
4075 smtp_printf("554 Security failure\r\n");
4079 tls_close(TRUE, TRUE);
4084 /* The ACL for QUIT is provided for gathering statistical information or
4085 similar; it does not affect the response code, but it can supply a custom
4090 incomplete_transaction_log(US"QUIT");
4091 if (acl_smtp_quit != NULL)
4093 rc = acl_check(ACL_WHERE_QUIT, NULL, acl_smtp_quit, &user_msg, &log_msg);
4095 log_write(0, LOG_MAIN|LOG_PANIC, "ACL for QUIT returned ERROR: %s",
4098 if (user_msg == NULL)
4099 smtp_printf("221 %s closing connection\r\n", smtp_active_hostname);
4101 smtp_respond(US"221", 3, TRUE, user_msg);
4104 tls_close(TRUE, TRUE);
4108 log_write(L_smtp_connection, LOG_MAIN, "%s closed by QUIT",
4109 smtp_get_connection_info());
4115 incomplete_transaction_log(US"RSET");
4116 smtp_reset(reset_point);
4118 smtp_printf("250 Reset OK\r\n");
4119 cmd_list[CMD_LIST_RSET].is_mail_cmd = FALSE;
4125 smtp_printf("250 OK\r\n");
4129 /* Show ETRN/EXPN/VRFY if there's an ACL for checking hosts; if actually
4130 used, a check will be done for permitted hosts. Show STARTTLS only if not
4131 already in a TLS session and if it would be advertised in the EHLO
4136 smtp_printf("214-Commands supported:\r\n");
4140 Ustrcat(buffer, " AUTH");
4142 if (tls_in.active < 0 &&
4143 verify_check_host(&tls_advertise_hosts) != FAIL)
4144 Ustrcat(buffer, " STARTTLS");
4146 Ustrcat(buffer, " HELO EHLO MAIL RCPT DATA");
4147 Ustrcat(buffer, " NOOP QUIT RSET HELP");
4148 if (acl_smtp_etrn != NULL) Ustrcat(buffer, " ETRN");
4149 if (acl_smtp_expn != NULL) Ustrcat(buffer, " EXPN");
4150 if (acl_smtp_vrfy != NULL) Ustrcat(buffer, " VRFY");
4151 smtp_printf("214%s\r\n", buffer);
4157 incomplete_transaction_log(US"connection lost");
4158 smtp_notquit_exit(US"connection-lost", US"421",
4159 US"%s lost input connection", smtp_active_hostname);
4161 /* Don't log by default unless in the middle of a message, as some mailers
4162 just drop the call rather than sending QUIT, and it clutters up the logs.
4165 if (sender_address != NULL || recipients_count > 0)
4166 log_write(L_lost_incoming_connection,
4168 "unexpected %s while reading SMTP command from %s%s",
4169 sender_host_unknown? "EOF" : "disconnection",
4170 host_and_ident(FALSE), smtp_read_error);
4172 else log_write(L_smtp_connection, LOG_MAIN, "%s lost%s",
4173 smtp_get_connection_info(), smtp_read_error);
4181 if (sender_address != NULL)
4183 done = synprot_error(L_smtp_protocol_error, 503, NULL,
4184 US"ETRN is not permitted inside a transaction");
4188 log_write(L_etrn, LOG_MAIN, "ETRN %s received from %s", smtp_cmd_argument,
4189 host_and_ident(FALSE));
4191 rc = acl_check(ACL_WHERE_ETRN, NULL, acl_smtp_etrn, &user_msg, &log_msg);
4194 done = smtp_handle_acl_fail(ACL_WHERE_ETRN, rc, user_msg, log_msg);
4198 /* Compute the serialization key for this command. */
4200 etrn_serialize_key = string_sprintf("etrn-%s\n", smtp_cmd_data);
4202 /* If a command has been specified for running as a result of ETRN, we
4203 permit any argument to ETRN. If not, only the # standard form is permitted,
4204 since that is strictly the only kind of ETRN that can be implemented
4205 according to the RFC. */
4207 if (smtp_etrn_command != NULL)
4211 etrn_command = smtp_etrn_command;
4212 deliver_domain = smtp_cmd_data;
4213 rc = transport_set_up_command(&argv, smtp_etrn_command, TRUE, 0, NULL,
4214 US"ETRN processing", &error);
4215 deliver_domain = NULL;
4218 log_write(0, LOG_MAIN|LOG_PANIC, "failed to set up ETRN command: %s",
4220 smtp_printf("458 Internal failure\r\n");
4225 /* Else set up to call Exim with the -R option. */
4229 if (*smtp_cmd_data++ != '#')
4231 done = synprot_error(L_smtp_syntax_error, 501, NULL,
4232 US"argument must begin with #");
4235 etrn_command = US"exim -R";
4236 argv = child_exec_exim(CEE_RETURN_ARGV, TRUE, NULL, TRUE, 2, US"-R",
4240 /* If we are host-testing, don't actually do anything. */
4246 debug_printf("ETRN command is: %s\n", etrn_command);
4247 debug_printf("ETRN command execution skipped\n");
4249 if (user_msg == NULL) smtp_printf("250 OK\r\n");
4250 else smtp_user_msg(US"250", user_msg);
4255 /* If ETRN queue runs are to be serialized, check the database to
4256 ensure one isn't already running. */
4258 if (smtp_etrn_serialize && !enq_start(etrn_serialize_key))
4260 smtp_printf("458 Already processing %s\r\n", smtp_cmd_data);
4264 /* Fork a child process and run the command. We don't want to have to
4265 wait for the process at any point, so set SIGCHLD to SIG_IGN before
4266 forking. It should be set that way anyway for external incoming SMTP,
4267 but we save and restore to be tidy. If serialization is required, we
4268 actually run the command in yet another process, so we can wait for it
4269 to complete and then remove the serialization lock. */
4271 oldsignal = signal(SIGCHLD, SIG_IGN);
4273 if ((pid = fork()) == 0)
4275 smtp_input = FALSE; /* This process is not associated with the */
4276 (void)fclose(smtp_in); /* SMTP call any more. */
4277 (void)fclose(smtp_out);
4279 signal(SIGCHLD, SIG_DFL); /* Want to catch child */
4281 /* If not serializing, do the exec right away. Otherwise, fork down
4282 into another process. */
4284 if (!smtp_etrn_serialize || (pid = fork()) == 0)
4286 DEBUG(D_exec) debug_print_argv(argv);
4287 exim_nullstd(); /* Ensure std{in,out,err} exist */
4288 execv(CS argv[0], (char *const *)argv);
4289 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "exec of \"%s\" (ETRN) failed: %s",
4290 etrn_command, strerror(errno));
4291 _exit(EXIT_FAILURE); /* paranoia */
4294 /* Obey this if smtp_serialize and the 2nd fork yielded non-zero. That
4295 is, we are in the first subprocess, after forking again. All we can do
4296 for a failing fork is to log it. Otherwise, wait for the 2nd process to
4297 complete, before removing the serialization. */
4300 log_write(0, LOG_MAIN|LOG_PANIC, "2nd fork for serialized ETRN "
4301 "failed: %s", strerror(errno));
4305 DEBUG(D_any) debug_printf("waiting for serialized ETRN process %d\n",
4307 (void)wait(&status);
4308 DEBUG(D_any) debug_printf("serialized ETRN process %d ended\n",
4312 enq_end(etrn_serialize_key);
4313 _exit(EXIT_SUCCESS);
4316 /* Back in the top level SMTP process. Check that we started a subprocess
4317 and restore the signal state. */
4321 log_write(0, LOG_MAIN|LOG_PANIC, "fork of process for ETRN failed: %s",
4323 smtp_printf("458 Unable to fork process\r\n");
4324 if (smtp_etrn_serialize) enq_end(etrn_serialize_key);
4328 if (user_msg == NULL) smtp_printf("250 OK\r\n");
4329 else smtp_user_msg(US"250", user_msg);
4332 signal(SIGCHLD, oldsignal);
4337 done = synprot_error(L_smtp_syntax_error, 501, NULL,
4338 US"unexpected argument data");
4342 /* This currently happens only for NULLs, but could be extended. */
4345 done = synprot_error(L_smtp_syntax_error, 0, NULL, /* Just logs */
4346 US"NULL character(s) present (shown as '?')");
4347 smtp_printf("501 NULL characters are not allowed in SMTP commands\r\n");
4353 if (smtp_inend >= smtp_inbuffer + in_buffer_size)
4354 smtp_inend = smtp_inbuffer + in_buffer_size - 1;
4355 c = smtp_inend - smtp_inptr;
4356 if (c > 150) c = 150;
4358 incomplete_transaction_log(US"sync failure");
4359 log_write(0, LOG_MAIN|LOG_REJECT, "SMTP protocol synchronization error "
4360 "(next input sent too soon: pipelining was%s advertised): "
4361 "rejected \"%s\" %s next input=\"%s\"",
4362 pipelining_advertised? "" : " not",
4363 smtp_cmd_buffer, host_and_ident(TRUE),
4364 string_printing(smtp_inptr));
4365 smtp_notquit_exit(US"synchronization-error", US"554",
4366 US"SMTP synchronization error");
4367 done = 1; /* Pretend eof - drops connection */
4371 case TOO_MANY_NONMAIL_CMD:
4372 s = smtp_cmd_buffer;
4373 while (*s != 0 && !isspace(*s)) s++;
4374 incomplete_transaction_log(US"too many non-mail commands");
4375 log_write(0, LOG_MAIN|LOG_REJECT, "SMTP call from %s dropped: too many "
4376 "nonmail commands (last was \"%.*s\")", host_and_ident(FALSE),
4377 (int)(s - smtp_cmd_buffer), smtp_cmd_buffer);
4378 smtp_notquit_exit(US"bad-commands", US"554", US"Too many nonmail commands");
4379 done = 1; /* Pretend eof - drops connection */
4384 if (unknown_command_count++ >= smtp_max_unknown_commands)
4386 log_write(L_smtp_syntax_error, LOG_MAIN,
4387 "SMTP syntax error in \"%s\" %s %s",
4388 string_printing(smtp_cmd_buffer), host_and_ident(TRUE),
4389 US"unrecognized command");
4390 incomplete_transaction_log(US"unrecognized command");
4391 smtp_notquit_exit(US"bad-commands", US"500",
4392 US"Too many unrecognized commands");
4394 log_write(0, LOG_MAIN|LOG_REJECT, "SMTP call from %s dropped: too many "
4395 "unrecognized commands (last was \"%s\")", host_and_ident(FALSE),
4399 done = synprot_error(L_smtp_syntax_error, 500, NULL,
4400 US"unrecognized command");
4404 /* This label is used by goto's inside loops that want to break out to
4405 the end of the command-processing loop. */
4408 last_was_rej_mail = was_rej_mail; /* Remember some last commands for */
4409 last_was_rcpt = was_rcpt; /* protocol error handling */
4413 return done - 2; /* Convert yield values */
4416 /* End of smtp_in.c */