1 /* $Cambridge: exim/src/src/smtp_in.c,v 1.42 2006/09/18 14:49:23 ph10 Exp $ */
3 /*************************************************
4 * Exim - an Internet mail transport agent *
5 *************************************************/
7 /* Copyright (c) University of Cambridge 1995 - 2006 */
8 /* See the file NOTICE for conditions of use and distribution. */
10 /* Functions for handling an incoming SMTP call. */
16 /* Initialize for TCP wrappers if so configured. It appears that the macro
17 HAVE_IPV6 is used in some versions of the tcpd.h header, so we unset it before
18 including that header, and restore its value afterwards. */
20 #ifdef USE_TCP_WRAPPERS
23 #define EXIM_HAVE_IPV6
29 #define HAVE_IPV6 TRUE
32 int allow_severity = LOG_INFO;
33 int deny_severity = LOG_NOTICE;
37 /* Size of buffer for reading SMTP commands. We used to use 512, as defined
38 by RFC 821. However, RFC 1869 specifies that this must be increased for SMTP
39 commands that accept arguments, and this in particular applies to AUTH, where
40 the data can be quite long. */
42 #define smtp_cmd_buffer_size 2048
44 /* Size of buffer for reading SMTP incoming packets */
46 #define in_buffer_size 8192
48 /* Structure for SMTP command list */
55 short int is_mail_cmd;
58 /* Codes for identifying commands. We order them so that those that come first
59 are those for which synchronization is always required. Checking this can help
63 /* These commands are required to be synchronized, i.e. to be the last in a
64 block of commands when pipelining. */
66 HELO_CMD, EHLO_CMD, DATA_CMD, /* These are listed in the pipelining */
67 VRFY_CMD, EXPN_CMD, NOOP_CMD, /* RFC as requiring synchronization */
68 ETRN_CMD, /* This by analogy with TURN from the RFC */
69 STARTTLS_CMD, /* Required by the STARTTLS RFC */
71 /* This is a dummy to identify the non-sync commands when pipelining */
73 NON_SYNC_CMD_PIPELINING,
75 /* These commands need not be synchronized when pipelining */
77 MAIL_CMD, RCPT_CMD, RSET_CMD,
79 /* This is a dummy to identify the non-sync commands when not pipelining */
81 NON_SYNC_CMD_NON_PIPELINING,
83 /* I have been unable to find a statement about the use of pipelining
84 with AUTH, so to be on the safe side it is here, though I kind of feel
85 it should be up there with the synchronized commands. */
89 /* I'm not sure about these, but I don't think they matter. */
93 /* These are specials that don't correspond to actual commands */
95 EOF_CMD, OTHER_CMD, BADARG_CMD, BADCHAR_CMD, BADSYN_CMD,
96 TOO_MANY_NONMAIL_CMD };
100 /*************************************************
101 * Local static variables *
102 *************************************************/
104 static auth_instance *authenticated_by;
105 static BOOL auth_advertised;
107 static BOOL tls_advertised;
110 static BOOL helo_required = FALSE;
111 static BOOL helo_verify = FALSE;
112 static BOOL helo_seen;
113 static BOOL helo_accept_junk;
114 static BOOL count_nonmail;
115 static BOOL pipelining_advertised;
116 static int nonmail_command_count;
117 static int synprot_error_count;
118 static int unknown_command_count;
119 static int sync_cmd_limit;
120 static int smtp_write_error = 0;
122 /* We need to know the position of RSET, HELO, EHLO, AUTH, and STARTTLS. Their
123 final fields of all except AUTH are forced TRUE at the start of a new message
124 setup, to allow one of each between messages that is not counted as a nonmail
125 command. (In fact, only one of HELO/EHLO is not counted.) Also, we have to
126 allow a new EHLO after starting up TLS.
128 AUTH is "falsely" labelled as a mail command initially, so that it doesn't get
129 counted. However, the flag is changed when AUTH is received, so that multiple
130 failing AUTHs will eventually hit the limit. After a successful AUTH, another
131 AUTH is already forbidden. After a TLS session is started, AUTH's flag is again
132 forced TRUE, to allow for the re-authentication that can happen at that point.
134 QUIT is also "falsely" labelled as a mail command so that it doesn't up the
135 count of non-mail commands and possibly provoke an error. */
137 static smtp_cmd_list cmd_list[] = {
138 { "rset", sizeof("rset")-1, RSET_CMD, FALSE, FALSE }, /* First */
139 { "helo", sizeof("helo")-1, HELO_CMD, TRUE, FALSE },
140 { "ehlo", sizeof("ehlo")-1, EHLO_CMD, TRUE, FALSE },
141 { "auth", sizeof("auth")-1, AUTH_CMD, TRUE, TRUE },
143 { "starttls", sizeof("starttls")-1, STARTTLS_CMD, FALSE, FALSE },
146 /* If you change anything above here, also fix the definitions below. */
148 { "mail from:", sizeof("mail from:")-1, MAIL_CMD, TRUE, TRUE },
149 { "rcpt to:", sizeof("rcpt to:")-1, RCPT_CMD, TRUE, TRUE },
150 { "data", sizeof("data")-1, DATA_CMD, FALSE, TRUE },
151 { "quit", sizeof("quit")-1, QUIT_CMD, FALSE, TRUE },
152 { "noop", sizeof("noop")-1, NOOP_CMD, TRUE, FALSE },
153 { "etrn", sizeof("etrn")-1, ETRN_CMD, TRUE, FALSE },
154 { "vrfy", sizeof("vrfy")-1, VRFY_CMD, TRUE, FALSE },
155 { "expn", sizeof("expn")-1, EXPN_CMD, TRUE, FALSE },
156 { "help", sizeof("help")-1, HELP_CMD, TRUE, FALSE }
159 static smtp_cmd_list *cmd_list_end =
160 cmd_list + sizeof(cmd_list)/sizeof(smtp_cmd_list);
162 #define CMD_LIST_RSET 0
163 #define CMD_LIST_HELO 1
164 #define CMD_LIST_EHLO 2
165 #define CMD_LIST_AUTH 3
166 #define CMD_LIST_STARTTLS 4
168 static uschar *protocols[] = {
169 US"local-smtp", /* HELO */
170 US"local-smtps", /* The rare case EHLO->STARTTLS->HELO */
171 US"local-esmtp", /* EHLO */
172 US"local-esmtps", /* EHLO->STARTTLS->EHLO */
173 US"local-esmtpa", /* EHLO->AUTH */
174 US"local-esmtpsa" /* EHLO->STARTTLS->EHLO->AUTH */
179 #define pcrpted 1 /* added to pextend or pnormal */
180 #define pauthed 2 /* added to pextend */
181 #define pnlocal 6 /* offset to remove "local" */
183 /* When reading SMTP from a remote host, we have to use our own versions of the
184 C input-reading functions, in order to be able to flush the SMTP output only
185 when about to read more data from the socket. This is the only way to get
186 optimal performance when the client is using pipelining. Flushing for every
187 command causes a separate packet and reply packet each time; saving all the
188 responses up (when pipelining) combines them into one packet and one response.
190 For simplicity, these functions are used for *all* SMTP input, not only when
191 receiving over a socket. However, after setting up a secure socket (SSL), input
192 is read via the OpenSSL library, and another set of functions is used instead
195 These functions are set in the receive_getc etc. variables and called with the
196 same interface as the C functions. However, since there can only ever be
197 one incoming SMTP call, we just use a single buffer and flags. There is no need
198 to implement a complicated private FILE-like structure.*/
200 static uschar *smtp_inbuffer;
201 static uschar *smtp_inptr;
202 static uschar *smtp_inend;
203 static int smtp_had_eof;
204 static int smtp_had_error;
207 /*************************************************
208 * SMTP version of getc() *
209 *************************************************/
211 /* This gets the next byte from the SMTP input buffer. If the buffer is empty,
212 it flushes the output, and refills the buffer, with a timeout. The signal
213 handler is set appropriately by the calling function. This function is not used
214 after a connection has negotated itself into an TLS/SSL state.
217 Returns: the next character or EOF
223 if (smtp_inptr >= smtp_inend)
227 if (smtp_receive_timeout > 0) alarm(smtp_receive_timeout);
228 rc = read(fileno(smtp_in), smtp_inbuffer, in_buffer_size);
233 /* Must put the error text in fixed store, because this might be during
234 header reading, where it releases unused store above the header. */
237 smtp_had_error = save_errno;
238 smtp_read_error = string_copy_malloc(
239 string_sprintf(" (error: %s)", strerror(save_errno)));
241 else smtp_had_eof = 1;
244 smtp_inend = smtp_inbuffer + rc;
245 smtp_inptr = smtp_inbuffer;
247 return *smtp_inptr++;
252 /*************************************************
253 * SMTP version of ungetc() *
254 *************************************************/
256 /* Puts a character back in the input buffer. Only ever
262 Returns: the character
268 *(--smtp_inptr) = ch;
275 /*************************************************
276 * SMTP version of feof() *
277 *************************************************/
279 /* Tests for a previous EOF
282 Returns: non-zero if the eof flag is set
294 /*************************************************
295 * SMTP version of ferror() *
296 *************************************************/
298 /* Tests for a previous read error, and returns with errno
299 restored to what it was when the error was detected.
302 Returns: non-zero if the error flag is set
308 errno = smtp_had_error;
309 return smtp_had_error;
315 /*************************************************
316 * Write formatted string to SMTP channel *
317 *************************************************/
319 /* This is a separate function so that we don't have to repeat everything for
320 TLS support or debugging. It is global so that the daemon and the
321 authentication functions can use it. It does not return any error indication,
322 because major problems such as dropped connections won't show up till an output
323 flush for non-TLS connections. The smtp_fflush() function is available for
324 checking that: for convenience, TLS output errors are remembered here so that
325 they are also picked up later by smtp_fflush().
329 ... optional arguments
335 smtp_printf(char *format, ...)
342 va_start(ap, format);
343 (void) string_vformat(big_buffer, big_buffer_size, format, ap);
345 end = big_buffer + Ustrlen(big_buffer);
346 while ((cr = Ustrchr(big_buffer, '\r')) != NULL) /* lose CRs */
347 memmove(cr, cr + 1, (end--) - cr);
348 debug_printf("SMTP>> %s", big_buffer);
351 va_start(ap, format);
353 /* If in a TLS session we have to format the string, and then write it using a
359 if (!string_vformat(big_buffer, big_buffer_size, format, ap))
361 log_write(0, LOG_MAIN|LOG_PANIC, "string too large in smtp_printf");
362 smtp_closedown(US"Unexpected error");
363 exim_exit(EXIT_FAILURE);
365 if (tls_write(big_buffer, Ustrlen(big_buffer)) < 0) smtp_write_error = -1;
370 /* Otherwise, just use the standard library function. */
372 if (vfprintf(smtp_out, format, ap) < 0) smtp_write_error = -1;
378 /*************************************************
379 * Flush SMTP out and check for error *
380 *************************************************/
382 /* This function isn't currently used within Exim (it detects errors when it
383 tries to read the next SMTP input), but is available for use in local_scan().
384 For non-TLS connections, it flushes the output and checks for errors. For
385 TLS-connections, it checks for a previously-detected TLS write error.
388 Returns: 0 for no error; -1 after an error
394 if (tls_active < 0 && fflush(smtp_out) != 0) smtp_write_error = -1;
395 return smtp_write_error;
400 /*************************************************
401 * SMTP command read timeout *
402 *************************************************/
404 /* Signal handler for timing out incoming SMTP commands. This attempts to
407 Argument: signal number (SIGALRM)
412 command_timeout_handler(int sig)
414 sig = sig; /* Keep picky compilers happy */
415 log_write(L_lost_incoming_connection,
416 LOG_MAIN, "SMTP command timeout on%s connection from %s",
417 (tls_active >= 0)? " TLS" : "",
418 host_and_ident(FALSE));
419 if (smtp_batched_input)
420 moan_smtp_batch(NULL, "421 SMTP command timeout"); /* Does not return */
421 smtp_printf("421 %s: SMTP command timeout - closing connection\r\n",
422 smtp_active_hostname);
424 exim_exit(EXIT_FAILURE);
429 /*************************************************
431 *************************************************/
433 /* Signal handler for handling SIGTERM. Again, try to finish tidily.
435 Argument: signal number (SIGTERM)
440 command_sigterm_handler(int sig)
442 sig = sig; /* Keep picky compilers happy */
443 log_write(0, LOG_MAIN, "%s closed after SIGTERM", smtp_get_connection_info());
444 if (smtp_batched_input)
445 moan_smtp_batch(NULL, "421 SIGTERM received"); /* Does not return */
446 smtp_printf("421 %s: Service not available - closing connection\r\n",
447 smtp_active_hostname);
448 exim_exit(EXIT_FAILURE);
453 /*************************************************
454 * Read one command line *
455 *************************************************/
457 /* Strictly, SMTP commands coming over the net are supposed to end with CRLF.
458 There are sites that don't do this, and in any case internal SMTP probably
459 should check only for LF. Consequently, we check here for LF only. The line
460 ends up with [CR]LF removed from its end. If we get an overlong line, treat as
461 an unknown command. The command is read into the global smtp_cmd_buffer so that
462 it is available via $smtp_command.
464 The character reading routine sets up a timeout for each block actually read
465 from the input (which may contain more than one command). We set up a special
466 signal handler that closes down the session on a timeout. Control does not
470 check_sync if TRUE, check synchronization rules if global option is TRUE
472 Returns: a code identifying the command (enumerated above)
476 smtp_read_command(BOOL check_sync)
481 BOOL hadnull = FALSE;
483 os_non_restarting_signal(SIGALRM, command_timeout_handler);
485 while ((c = (receive_getc)()) != '\n' && c != EOF)
487 if (ptr >= smtp_cmd_buffer_size)
489 os_non_restarting_signal(SIGALRM, sigalrm_handler);
497 smtp_cmd_buffer[ptr++] = c;
500 receive_linecount++; /* For BSMTP errors */
501 os_non_restarting_signal(SIGALRM, sigalrm_handler);
503 /* If hit end of file, return pseudo EOF command. Whether we have a
504 part-line already read doesn't matter, since this is an error state. */
506 if (c == EOF) return EOF_CMD;
508 /* Remove any CR and white space at the end of the line, and terminate the
511 while (ptr > 0 && isspace(smtp_cmd_buffer[ptr-1])) ptr--;
512 smtp_cmd_buffer[ptr] = 0;
514 DEBUG(D_receive) debug_printf("SMTP<< %s\n", smtp_cmd_buffer);
516 /* NULLs are not allowed in SMTP commands */
518 if (hadnull) return BADCHAR_CMD;
520 /* Scan command list and return identity, having set the data pointer
521 to the start of the actual data characters. Check for SMTP synchronization
524 for (p = cmd_list; p < cmd_list_end; p++)
526 if (strncmpic(smtp_cmd_buffer, US p->name, p->len) == 0 &&
527 (smtp_cmd_buffer[p->len-1] == ':' || /* "mail from:" or "rcpt to:" */
528 smtp_cmd_buffer[p->len] == 0 ||
529 smtp_cmd_buffer[p->len] == ' '))
531 if (smtp_inptr < smtp_inend && /* Outstanding input */
532 p->cmd < sync_cmd_limit && /* Command should sync */
533 check_sync && /* Local flag set */
534 smtp_enforce_sync && /* Global flag set */
535 sender_host_address != NULL && /* Not local input */
536 !sender_host_notsocket) /* Really is a socket */
539 /* Point after the command, but don't skip over leading spaces till after
540 the following test, so that if it fails, the command name can easily be
543 smtp_cmd_argument = smtp_cmd_buffer + p->len;
545 /* Count non-mail commands from those hosts that are controlled in this
546 way. The default is all hosts. We don't waste effort checking the list
547 until we get a non-mail command, but then cache the result to save checking
548 again. If there's a DEFER while checking the host, assume it's in the list.
550 Note that one instance of RSET, EHLO/HELO, and STARTTLS is allowed at the
551 start of each incoming message by fiddling with the value in the table. */
555 if (count_nonmail == TRUE_UNSET) count_nonmail =
556 verify_check_host(&smtp_accept_max_nonmail_hosts) != FAIL;
557 if (count_nonmail && ++nonmail_command_count > smtp_accept_max_nonmail)
558 return TOO_MANY_NONMAIL_CMD;
561 /* Get the data pointer over leading spaces and return; if there is data
562 for a command that does not expect it, give the error centrally here. */
564 while (isspace(*smtp_cmd_argument)) smtp_cmd_argument++;
565 return (p->has_arg || *smtp_cmd_argument == 0)? p->cmd : BADARG_CMD;
569 /* Enforce synchronization for unknown commands */
571 if (smtp_inptr < smtp_inend && /* Outstanding input */
572 check_sync && /* Local flag set */
573 smtp_enforce_sync && /* Global flag set */
574 sender_host_address != NULL && /* Not local input */
575 !sender_host_notsocket) /* Really is a socket */
583 /*************************************************
584 * Forced closedown of call *
585 *************************************************/
587 /* This function is called from log.c when Exim is dying because of a serious
588 disaster, and also from some other places. If an incoming non-batched SMTP
589 channel is open, it swallows the rest of the incoming message if in the DATA
590 phase, sends the reply string, and gives an error to all subsequent commands
591 except QUIT. The existence of an SMTP call is detected by the non-NULLness of
594 Argument: SMTP reply string to send, excluding the code
599 smtp_closedown(uschar *message)
601 if (smtp_in == NULL || smtp_batched_input) return;
602 receive_swallow_smtp();
603 smtp_printf("421 %s\r\n", message);
607 switch(smtp_read_command(FALSE))
613 smtp_printf("221 %s closing connection\r\n", smtp_active_hostname);
618 smtp_printf("250 Reset OK\r\n");
622 smtp_printf("421 %s\r\n", message);
631 /*************************************************
632 * Set up connection info for logging *
633 *************************************************/
635 /* This function is called when logging information about an SMTP connection.
636 It sets up appropriate source information, depending on the type of connection.
637 If sender_fullhost is NULL, we are at a very early stage of the connection;
638 just use the IP address.
641 Returns: a string describing the connection
645 smtp_get_connection_info(void)
647 uschar *hostname = (sender_fullhost == NULL)?
648 sender_host_address : sender_fullhost;
651 return string_sprintf("SMTP connection from %s", hostname);
653 if (sender_host_unknown || sender_host_notsocket)
654 return string_sprintf("SMTP connection from %s", sender_ident);
657 return string_sprintf("SMTP connection from %s (via inetd)", hostname);
659 if ((log_extra_selector & LX_incoming_interface) != 0 &&
660 interface_address != NULL)
661 return string_sprintf("SMTP connection from %s I=[%s]:%d", hostname,
662 interface_address, interface_port);
664 return string_sprintf("SMTP connection from %s", hostname);
669 /*************************************************
670 * Check HELO line and set sender_helo_name *
671 *************************************************/
673 /* Check the format of a HELO line. The data for HELO/EHLO is supposed to be
674 the domain name of the sending host, or an ip literal in square brackets. The
675 arrgument is placed in sender_helo_name, which is in malloc store, because it
676 must persist over multiple incoming messages. If helo_accept_junk is set, this
677 host is permitted to send any old junk (needed for some broken hosts).
678 Otherwise, helo_allow_chars can be used for rogue characters in general
679 (typically people want to let in underscores).
682 s the data portion of the line (already past any white space)
684 Returns: TRUE or FALSE
688 check_helo(uschar *s)
691 uschar *end = s + Ustrlen(s);
692 BOOL yield = helo_accept_junk;
694 /* Discard any previous helo name */
696 if (sender_helo_name != NULL)
698 store_free(sender_helo_name);
699 sender_helo_name = NULL;
702 /* Skip tests if junk is permitted. */
706 /* Allow the new standard form for IPv6 address literals, namely,
707 [IPv6:....], and because someone is bound to use it, allow an equivalent
708 IPv4 form. Allow plain addresses as well. */
715 if (strncmpic(s, US"[IPv6:", 6) == 0)
716 yield = (string_is_ip_address(s+6, NULL) == 6);
717 else if (strncmpic(s, US"[IPv4:", 6) == 0)
718 yield = (string_is_ip_address(s+6, NULL) == 4);
720 yield = (string_is_ip_address(s+1, NULL) != 0);
725 /* Non-literals must be alpha, dot, hyphen, plus any non-valid chars
726 that have been configured (usually underscore - sigh). */
733 if (!isalnum(*s) && *s != '.' && *s != '-' &&
734 Ustrchr(helo_allow_chars, *s) == NULL)
744 /* Save argument if OK */
746 if (yield) sender_helo_name = string_copy_malloc(start);
754 /*************************************************
755 * Extract SMTP command option *
756 *************************************************/
758 /* This function picks the next option setting off the end of smtp_cmd_argument. It
759 is called for MAIL FROM and RCPT TO commands, to pick off the optional ESMTP
760 things that can appear there.
763 name point this at the name
764 value point this at the data string
766 Returns: TRUE if found an option
770 extract_option(uschar **name, uschar **value)
773 uschar *v = smtp_cmd_argument + Ustrlen(smtp_cmd_argument) -1;
774 while (isspace(*v)) v--;
777 while (v > smtp_cmd_argument && *v != '=' && !isspace(*v)) v--;
778 if (*v != '=') return FALSE;
781 while(isalpha(n[-1])) n--;
783 if (n[-1] != ' ') return FALSE;
798 /*************************************************
799 * Reset for new message *
800 *************************************************/
802 /* This function is called whenever the SMTP session is reset from
803 within either of the setup functions.
805 Argument: the stacking pool storage reset point
810 smtp_reset(void *reset_point)
813 store_reset(reset_point);
814 recipients_list = NULL;
815 rcpt_count = rcpt_defer_count = rcpt_fail_count =
816 raw_recipients_count = recipients_count = recipients_list_max = 0;
817 message_linecount = 0;
819 acl_added_headers = NULL;
820 queue_only_policy = FALSE;
821 deliver_freeze = FALSE; /* Can be set by ACL */
822 freeze_tell = freeze_tell_config; /* Can be set by ACL */
823 fake_response = OK; /* Can be set by ACL */
824 #ifdef WITH_CONTENT_SCAN
825 no_mbox_unspool = FALSE; /* Can be set by ACL */
827 submission_mode = FALSE; /* Can be set by ACL */
828 suppress_local_fixups = FALSE; /* Can be set by ACL */
829 active_local_from_check = local_from_check; /* Can be set by ACL */
830 active_local_sender_retain = local_sender_retain; /* Can be set by ACL */
831 sender_address = NULL;
832 submission_name = NULL; /* Can be set by ACL */
833 raw_sender = NULL; /* After SMTP rewrite, before qualifying */
834 sender_address_unrewritten = NULL; /* Set only after verify rewrite */
835 sender_verified_list = NULL; /* No senders verified */
836 memset(sender_address_cache, 0, sizeof(sender_address_cache));
837 memset(sender_domain_cache, 0, sizeof(sender_domain_cache));
838 authenticated_sender = NULL;
839 #ifdef EXPERIMENTAL_BRIGHTMAIL
843 #ifdef EXPERIMENTAL_DOMAINKEYS
846 #ifdef EXPERIMENTAL_SPF
847 spf_header_comment = NULL;
850 spf_smtp_comment = NULL;
852 body_linecount = body_zerocount = 0;
854 sender_rate = sender_rate_limit = sender_rate_period = NULL;
855 ratelimiters_mail = NULL; /* Updated by ratelimit ACL condition */
856 /* Note that ratelimiters_conn persists across resets. */
858 /* The message variables follow the connection variables. */
860 for (i = 0; i < ACL_MVARS; i++) acl_var[ACL_CVARS + i] = NULL;
862 /* The message body variables use malloc store. They may be set if this is
863 not the first message in an SMTP session and the previous message caused them
864 to be referenced in an ACL. */
866 if (message_body != NULL)
868 store_free(message_body);
872 if (message_body_end != NULL)
874 store_free(message_body_end);
875 message_body_end = NULL;
878 /* Warning log messages are also saved in malloc store. They are saved to avoid
879 repetition in the same message, but it seems right to repeat them for different
882 while (acl_warn_logged != NULL)
884 string_item *this = acl_warn_logged;
885 acl_warn_logged = acl_warn_logged->next;
894 /*************************************************
895 * Initialize for incoming batched SMTP message *
896 *************************************************/
898 /* This function is called from smtp_setup_msg() in the case when
899 smtp_batched_input is true. This happens when -bS is used to pass a whole batch
900 of messages in one file with SMTP commands between them. All errors must be
901 reported by sending a message, and only MAIL FROM, RCPT TO, and DATA are
902 relevant. After an error on a sender, or an invalid recipient, the remainder
903 of the message is skipped. The value of received_protocol is already set.
906 Returns: > 0 message successfully started (reached DATA)
907 = 0 QUIT read or end of file reached
912 smtp_setup_batch_msg(void)
915 void *reset_point = store_get(0);
917 /* Save the line count at the start of each transaction - single commands
918 like HELO and RSET count as whole transactions. */
920 bsmtp_transaction_linecount = receive_linecount;
922 if ((receive_feof)()) return 0; /* Treat EOF as QUIT */
924 smtp_reset(reset_point); /* Reset for start of message */
926 /* Deal with SMTP commands. This loop is exited by setting done to a POSITIVE
927 value. The values are 2 larger than the required yield of the function. */
932 uschar *recipient = NULL;
933 int start, end, sender_domain, recipient_domain;
935 switch(smtp_read_command(FALSE))
937 /* The HELO/EHLO commands set sender_address_helo if they have
938 valid data; otherwise they are ignored, except that they do
939 a reset of the state. */
944 check_helo(smtp_cmd_argument);
948 smtp_reset(reset_point);
949 bsmtp_transaction_linecount = receive_linecount;
953 /* The MAIL FROM command requires an address as an operand. All we
954 do here is to parse it for syntactic correctness. The form "<>" is
955 a special case which converts into an empty string. The start/end
956 pointers in the original are not used further for this address, as
957 it is the canonical extracted address which is all that is kept. */
960 if (sender_address != NULL)
961 /* The function moan_smtp_batch() does not return. */
962 moan_smtp_batch(smtp_cmd_buffer, "503 Sender already given");
964 if (smtp_cmd_argument[0] == 0)
965 /* The function moan_smtp_batch() does not return. */
966 moan_smtp_batch(smtp_cmd_buffer, "501 MAIL FROM must have an address operand");
968 /* Reset to start of message */
970 smtp_reset(reset_point);
972 /* Apply SMTP rewrite */
974 raw_sender = ((rewrite_existflags & rewrite_smtp) != 0)?
975 rewrite_one(smtp_cmd_argument, rewrite_smtp|rewrite_smtp_sender, NULL, FALSE,
976 US"", global_rewrite_rules) : smtp_cmd_argument;
978 /* Extract the address; the TRUE flag allows <> as valid */
981 parse_extract_address(raw_sender, &errmess, &start, &end, &sender_domain,
984 if (raw_sender == NULL)
985 /* The function moan_smtp_batch() does not return. */
986 moan_smtp_batch(smtp_cmd_buffer, "501 %s", errmess);
988 sender_address = string_copy(raw_sender);
990 /* Qualify unqualified sender addresses if permitted to do so. */
992 if (sender_domain == 0 && sender_address[0] != 0 && sender_address[0] != '@')
994 if (allow_unqualified_sender)
996 sender_address = rewrite_address_qualify(sender_address, FALSE);
997 DEBUG(D_receive) debug_printf("unqualified address %s accepted "
998 "and rewritten\n", raw_sender);
1000 /* The function moan_smtp_batch() does not return. */
1001 else moan_smtp_batch(smtp_cmd_buffer, "501 sender address must contain "
1007 /* The RCPT TO command requires an address as an operand. All we do
1008 here is to parse it for syntactic correctness. There may be any number
1009 of RCPT TO commands, specifying multiple senders. We build them all into
1010 a data structure that is in argc/argv format. The start/end values
1011 given by parse_extract_address are not used, as we keep only the
1012 extracted address. */
1015 if (sender_address == NULL)
1016 /* The function moan_smtp_batch() does not return. */
1017 moan_smtp_batch(smtp_cmd_buffer, "503 No sender yet given");
1019 if (smtp_cmd_argument[0] == 0)
1020 /* The function moan_smtp_batch() does not return. */
1021 moan_smtp_batch(smtp_cmd_buffer, "501 RCPT TO must have an address operand");
1023 /* Check maximum number allowed */
1025 if (recipients_max > 0 && recipients_count + 1 > recipients_max)
1026 /* The function moan_smtp_batch() does not return. */
1027 moan_smtp_batch(smtp_cmd_buffer, "%s too many recipients",
1028 recipients_max_reject? "552": "452");
1030 /* Apply SMTP rewrite, then extract address. Don't allow "<>" as a
1031 recipient address */
1033 recipient = ((rewrite_existflags & rewrite_smtp) != 0)?
1034 rewrite_one(smtp_cmd_argument, rewrite_smtp, NULL, FALSE, US"",
1035 global_rewrite_rules) : smtp_cmd_argument;
1037 /* rfc821_domains = TRUE; << no longer needed */
1038 recipient = parse_extract_address(recipient, &errmess, &start, &end,
1039 &recipient_domain, FALSE);
1040 /* rfc821_domains = FALSE; << no longer needed */
1042 if (recipient == NULL)
1043 /* The function moan_smtp_batch() does not return. */
1044 moan_smtp_batch(smtp_cmd_buffer, "501 %s", errmess);
1046 /* If the recipient address is unqualified, qualify it if permitted. Then
1047 add it to the list of recipients. */
1049 if (recipient_domain == 0)
1051 if (allow_unqualified_recipient)
1053 DEBUG(D_receive) debug_printf("unqualified address %s accepted\n",
1055 recipient = rewrite_address_qualify(recipient, TRUE);
1057 /* The function moan_smtp_batch() does not return. */
1058 else moan_smtp_batch(smtp_cmd_buffer, "501 recipient address must contain "
1061 receive_add_recipient(recipient, -1);
1065 /* The DATA command is legal only if it follows successful MAIL FROM
1066 and RCPT TO commands. This function is complete when a valid DATA
1067 command is encountered. */
1070 if (sender_address == NULL || recipients_count <= 0)
1072 /* The function moan_smtp_batch() does not return. */
1073 if (sender_address == NULL)
1074 moan_smtp_batch(smtp_cmd_buffer,
1075 "503 MAIL FROM:<sender> command must precede DATA");
1077 moan_smtp_batch(smtp_cmd_buffer,
1078 "503 RCPT TO:<recipient> must precede DATA");
1082 done = 3; /* DATA successfully achieved */
1083 message_ended = END_NOTENDED; /* Indicate in middle of message */
1088 /* The VRFY, EXPN, HELP, ETRN, and NOOP commands are ignored. */
1095 bsmtp_transaction_linecount = receive_linecount;
1106 /* The function moan_smtp_batch() does not return. */
1107 moan_smtp_batch(smtp_cmd_buffer, "501 Unexpected argument data");
1112 /* The function moan_smtp_batch() does not return. */
1113 moan_smtp_batch(smtp_cmd_buffer, "501 Unexpected NULL in SMTP command");
1118 /* The function moan_smtp_batch() does not return. */
1119 moan_smtp_batch(smtp_cmd_buffer, "500 Command unrecognized");
1124 return done - 2; /* Convert yield values */
1130 /*************************************************
1131 * Start an SMTP session *
1132 *************************************************/
1134 /* This function is called at the start of an SMTP session. Thereafter,
1135 smtp_setup_msg() is called to initiate each separate message. This
1136 function does host-specific testing, and outputs the banner line.
1139 Returns: FALSE if the session can not continue; something has
1140 gone wrong, or the connection to the host is blocked
1144 smtp_start_session(void)
1150 /* Default values for certain variables */
1152 helo_seen = esmtp = helo_accept_junk = FALSE;
1153 count_nonmail = TRUE_UNSET;
1154 synprot_error_count = unknown_command_count = nonmail_command_count = 0;
1155 smtp_delay_mail = smtp_rlm_base;
1156 auth_advertised = FALSE;
1157 pipelining_advertised = FALSE;
1158 sync_cmd_limit = NON_SYNC_CMD_NON_PIPELINING;
1160 memset(sender_host_cache, 0, sizeof(sender_host_cache));
1162 /* If receiving by -bs from a trusted user, or testing with -bh, we allow
1163 authentication settings from -oMaa to remain in force. */
1165 if (!host_checking && !sender_host_notsocket) sender_host_authenticated = NULL;
1166 authenticated_by = NULL;
1169 tls_cipher = tls_peerdn = NULL;
1170 tls_advertised = FALSE;
1173 /* Reset ACL connection variables */
1175 for (i = 0; i < ACL_CVARS; i++) acl_var[i] = NULL;
1177 /* Allow for trailing 0 in the command buffer. */
1179 smtp_cmd_buffer = (uschar *)malloc(smtp_cmd_buffer_size + 1);
1180 if (smtp_cmd_buffer == NULL)
1181 log_write(0, LOG_MAIN|LOG_PANIC_DIE,
1182 "malloc() failed for SMTP command buffer");
1184 /* For batched input, the protocol setting can be overridden from the
1185 command line by a trusted caller. */
1187 if (smtp_batched_input)
1189 if (received_protocol == NULL) received_protocol = US"local-bsmtp";
1192 /* For non-batched SMTP input, the protocol setting is forced here. It will be
1193 reset later if any of EHLO/AUTH/STARTTLS are received. */
1197 protocols[pnormal] + ((sender_host_address != NULL)? pnlocal : 0);
1199 /* Set up the buffer for inputting using direct read() calls, and arrange to
1200 call the local functions instead of the standard C ones. */
1202 smtp_inbuffer = (uschar *)malloc(in_buffer_size);
1203 if (smtp_inbuffer == NULL)
1204 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "malloc() failed for SMTP input buffer");
1205 receive_getc = smtp_getc;
1206 receive_ungetc = smtp_ungetc;
1207 receive_feof = smtp_feof;
1208 receive_ferror = smtp_ferror;
1209 smtp_inptr = smtp_inend = smtp_inbuffer;
1210 smtp_had_eof = smtp_had_error = 0;
1212 /* Set up the message size limit; this may be host-specific */
1214 thismessage_size_limit = expand_string_integer(message_size_limit, TRUE);
1215 if (expand_string_message != NULL)
1217 if (thismessage_size_limit == -1)
1218 log_write(0, LOG_MAIN|LOG_PANIC, "unable to expand message_size_limit: "
1219 "%s", expand_string_message);
1221 log_write(0, LOG_MAIN|LOG_PANIC, "invalid message_size_limit: "
1222 "%s", expand_string_message);
1223 smtp_closedown(US"Temporary local problem - please try later");
1227 /* When a message is input locally via the -bs or -bS options, sender_host_
1228 unknown is set unless -oMa was used to force an IP address, in which case it
1229 is checked like a real remote connection. When -bs is used from inetd, this
1230 flag is not set, causing the sending host to be checked. The code that deals
1231 with IP source routing (if configured) is never required for -bs or -bS and
1232 the flag sender_host_notsocket is used to suppress it.
1234 If smtp_accept_max and smtp_accept_reserve are set, keep some connections in
1235 reserve for certain hosts and/or networks. */
1237 if (!sender_host_unknown)
1240 BOOL reserved_host = FALSE;
1242 /* Look up IP options (source routing info) on the socket if this is not an
1243 -oMa "host", and if any are found, log them and drop the connection.
1245 Linux (and others now, see below) is different to everyone else, so there
1246 has to be some conditional compilation here. Versions of Linux before 2.1.15
1247 used a structure whose name was "options". Somebody finally realized that
1248 this name was silly, and it got changed to "ip_options". I use the
1249 newer name here, but there is a fudge in the script that sets up os.h
1250 to define a macro in older Linux systems.
1252 Sigh. Linux is a fast-moving target. Another generation of Linux uses
1253 glibc 2, which has chosen ip_opts for the structure name. This is now
1254 really a glibc thing rather than a Linux thing, so the condition name
1255 has been changed to reflect this. It is relevant also to GNU/Hurd.
1257 Mac OS 10.x (Darwin) is like the later glibc versions, but without the
1258 setting of the __GLIBC__ macro, so we can't detect it automatically. There's
1259 a special macro defined in the os.h file.
1261 Some DGUX versions on older hardware appear not to support IP options at
1262 all, so there is now a general macro which can be set to cut out this
1265 How to do this properly in IPv6 is not yet known. */
1267 #if !HAVE_IPV6 && !defined(NO_IP_OPTIONS)
1269 #ifdef GLIBC_IP_OPTIONS
1270 #if (!defined __GLIBC__) || (__GLIBC__ < 2)
1275 #elif defined DARWIN_IP_OPTIONS
1281 if (!host_checking && !sender_host_notsocket)
1284 EXIM_SOCKLEN_T optlen = sizeof(struct ip_options) + MAX_IPOPTLEN;
1285 struct ip_options *ipopt = store_get(optlen);
1287 struct ip_opts ipoptblock;
1288 struct ip_opts *ipopt = &ipoptblock;
1289 EXIM_SOCKLEN_T optlen = sizeof(ipoptblock);
1291 struct ipoption ipoptblock;
1292 struct ipoption *ipopt = &ipoptblock;
1293 EXIM_SOCKLEN_T optlen = sizeof(ipoptblock);
1296 /* Occasional genuine failures of getsockopt() have been seen - for
1297 example, "reset by peer". Therefore, just log and give up on this
1298 call, unless the error is ENOPROTOOPT. This error is given by systems
1299 that have the interfaces but not the mechanism - e.g. GNU/Hurd at the time
1300 of writing. So for that error, carry on - we just can't do an IP options
1303 DEBUG(D_receive) debug_printf("checking for IP options\n");
1305 if (getsockopt(fileno(smtp_out), IPPROTO_IP, IP_OPTIONS, (uschar *)(ipopt),
1308 if (errno != ENOPROTOOPT)
1310 log_write(0, LOG_MAIN, "getsockopt() failed from %s: %s",
1311 host_and_ident(FALSE), strerror(errno));
1312 smtp_printf("451 SMTP service not available\r\n");
1317 /* Deal with any IP options that are set. On the systems I have looked at,
1318 the value of MAX_IPOPTLEN has been 40, meaning that there should never be
1319 more logging data than will fit in big_buffer. Nevertheless, after somebody
1320 questioned this code, I've added in some paranoid checking. */
1322 else if (optlen > 0)
1324 uschar *p = big_buffer;
1325 uschar *pend = big_buffer + big_buffer_size;
1326 uschar *opt, *adptr;
1328 struct in_addr addr;
1331 uschar *optstart = (uschar *)(ipopt->__data);
1333 uschar *optstart = (uschar *)(ipopt->ip_opts);
1335 uschar *optstart = (uschar *)(ipopt->ipopt_list);
1338 DEBUG(D_receive) debug_printf("IP options exist\n");
1340 Ustrcpy(p, "IP options on incoming call:");
1343 for (opt = optstart; opt != NULL &&
1344 opt < (uschar *)(ipopt) + optlen;)
1358 if (!string_format(p, pend-p, " %s [@%s",
1359 (*opt == IPOPT_SSRR)? "SSRR" : "LSRR",
1361 inet_ntoa(*((struct in_addr *)(&(ipopt->faddr))))))
1363 inet_ntoa(ipopt->ip_dst)))
1365 inet_ntoa(ipopt->ipopt_dst)))
1373 optcount = (opt[1] - 3) / sizeof(struct in_addr);
1375 while (optcount-- > 0)
1377 memcpy(&addr, adptr, sizeof(addr));
1378 if (!string_format(p, pend - p - 1, "%s%s",
1379 (optcount == 0)? ":" : "@", inet_ntoa(addr)))
1385 adptr += sizeof(struct in_addr);
1394 if (pend - p < 4 + 3*opt[1]) { opt = NULL; break; }
1397 for (i = 0; i < opt[1]; i++)
1399 sprintf(CS p, "%2.2x ", opt[i]);
1410 log_write(0, LOG_MAIN, "%s", big_buffer);
1412 /* Refuse any call with IP options. This is what tcpwrappers 7.5 does. */
1414 log_write(0, LOG_MAIN|LOG_REJECT,
1415 "connection from %s refused (IP options)", host_and_ident(FALSE));
1417 smtp_printf("554 SMTP service not available\r\n");
1421 /* Length of options = 0 => there are no options */
1423 else DEBUG(D_receive) debug_printf("no IP options found\n");
1425 #endif /* HAVE_IPV6 && !defined(NO_IP_OPTIONS) */
1427 /* Set keep-alive in socket options. The option is on by default. This
1428 setting is an attempt to get rid of some hanging connections that stick in
1429 read() when the remote end (usually a dialup) goes away. */
1431 if (smtp_accept_keepalive && !sender_host_notsocket)
1432 ip_keepalive(fileno(smtp_out), sender_host_address, FALSE);
1434 /* If the current host matches host_lookup, set the name by doing a
1435 reverse lookup. On failure, sender_host_name will be NULL and
1436 host_lookup_failed will be TRUE. This may or may not be serious - optional
1439 if (verify_check_host(&host_lookup) == OK)
1441 (void)host_name_lookup();
1442 host_build_sender_fullhost();
1445 /* Delay this until we have the full name, if it is looked up. */
1447 set_process_info("handling incoming connection from %s",
1448 host_and_ident(FALSE));
1450 /* Start up TLS if tls_on_connect is set. This is for supporting the legacy
1451 smtps port for use with older style SSL MTAs. */
1454 if (tls_on_connect && tls_server_start(tls_require_ciphers) != OK)
1458 /* Test for explicit connection rejection */
1460 if (verify_check_host(&host_reject_connection) == OK)
1462 log_write(L_connection_reject, LOG_MAIN|LOG_REJECT, "refused connection "
1463 "from %s (host_reject_connection)", host_and_ident(FALSE));
1464 smtp_printf("554 SMTP service not available\r\n");
1468 /* Test with TCP Wrappers if so configured. There is a problem in that
1469 hosts_ctl() returns 0 (deny) under a number of system failure circumstances,
1470 such as disks dying. In these cases, it is desirable to reject with a 4xx
1471 error instead of a 5xx error. There isn't a "right" way to detect such
1472 problems. The following kludge is used: errno is zeroed before calling
1473 hosts_ctl(). If the result is "reject", a 5xx error is given only if the
1474 value of errno is 0 or ENOENT (which happens if /etc/hosts.{allow,deny} does
1477 #ifdef USE_TCP_WRAPPERS
1479 if (!hosts_ctl("exim",
1480 (sender_host_name == NULL)? STRING_UNKNOWN : CS sender_host_name,
1481 (sender_host_address == NULL)? STRING_UNKNOWN : CS sender_host_address,
1482 (sender_ident == NULL)? STRING_UNKNOWN : CS sender_ident))
1484 if (errno == 0 || errno == ENOENT)
1486 HDEBUG(D_receive) debug_printf("tcp wrappers rejection\n");
1487 log_write(L_connection_reject,
1488 LOG_MAIN|LOG_REJECT, "refused connection from %s "
1489 "(tcp wrappers)", host_and_ident(FALSE));
1490 smtp_printf("554 SMTP service not available\r\n");
1494 int save_errno = errno;
1495 HDEBUG(D_receive) debug_printf("tcp wrappers rejected with unexpected "
1496 "errno value %d\n", save_errno);
1497 log_write(L_connection_reject,
1498 LOG_MAIN|LOG_REJECT, "temporarily refused connection from %s "
1499 "(tcp wrappers errno=%d)", host_and_ident(FALSE), save_errno);
1500 smtp_printf("451 Temporary local problem - please try later\r\n");
1506 /* Check for reserved slots. Note that the count value doesn't include
1507 this process, as it gets upped in the parent process. */
1509 if (smtp_accept_max > 0 &&
1510 smtp_accept_count + 1 > smtp_accept_max - smtp_accept_reserve)
1512 if ((rc = verify_check_host(&smtp_reserve_hosts)) != OK)
1514 log_write(L_connection_reject,
1515 LOG_MAIN, "temporarily refused connection from %s: not in "
1516 "reserve list: connected=%d max=%d reserve=%d%s",
1517 host_and_ident(FALSE), smtp_accept_count, smtp_accept_max,
1518 smtp_accept_reserve, (rc == DEFER)? " (lookup deferred)" : "");
1519 smtp_printf("421 %s: Too many concurrent SMTP connections; "
1520 "please try again later\r\n", smtp_active_hostname);
1523 reserved_host = TRUE;
1526 /* If a load level above which only messages from reserved hosts are
1527 accepted is set, check the load. For incoming calls via the daemon, the
1528 check is done in the superior process if there are no reserved hosts, to
1529 save a fork. In all cases, the load average will already be available
1530 in a global variable at this point. */
1532 if (smtp_load_reserve >= 0 &&
1533 load_average > smtp_load_reserve &&
1535 verify_check_host(&smtp_reserve_hosts) != OK)
1537 log_write(L_connection_reject,
1538 LOG_MAIN, "temporarily refused connection from %s: not in "
1539 "reserve list and load average = %.2f", host_and_ident(FALSE),
1540 (double)load_average/1000.0);
1541 smtp_printf("421 %s: Too much load; please try again later\r\n",
1542 smtp_active_hostname);
1546 /* Determine whether unqualified senders or recipients are permitted
1547 for this host. Unfortunately, we have to do this every time, in order to
1548 set the flags so that they can be inspected when considering qualifying
1549 addresses in the headers. For a site that permits no qualification, this
1550 won't take long, however. */
1552 allow_unqualified_sender =
1553 verify_check_host(&sender_unqualified_hosts) == OK;
1555 allow_unqualified_recipient =
1556 verify_check_host(&recipient_unqualified_hosts) == OK;
1558 /* Determine whether HELO/EHLO is required for this host. The requirement
1559 can be hard or soft. */
1561 helo_required = verify_check_host(&helo_verify_hosts) == OK;
1563 helo_verify = verify_check_host(&helo_try_verify_hosts) == OK;
1565 /* Determine whether this hosts is permitted to send syntactic junk
1566 after a HELO or EHLO command. */
1568 helo_accept_junk = verify_check_host(&helo_accept_junk_hosts) == OK;
1571 /* For batch SMTP input we are now done. */
1573 if (smtp_batched_input) return TRUE;
1575 /* Run the ACL if it exists */
1577 if (acl_smtp_connect != NULL)
1580 uschar *user_msg, *log_msg;
1581 rc = acl_check(ACL_WHERE_CONNECT, NULL, acl_smtp_connect, &user_msg,
1585 (void)smtp_handle_acl_fail(ACL_WHERE_CONNECT, rc, user_msg, log_msg);
1590 /* Output the initial message for a two-way SMTP connection. It may contain
1591 newlines, which then cause a multi-line response to be given. */
1593 s = expand_string(smtp_banner);
1595 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "Expansion of \"%s\" (smtp_banner) "
1596 "failed: %s", smtp_banner, expand_string_message);
1598 /* Remove any terminating newlines; might as well remove trailing space too */
1601 while (p > s && isspace(p[-1])) p--;
1604 /* It seems that CC:Mail is braindead, and assumes that the greeting message
1605 is all contained in a single IP packet. The original code wrote out the
1606 greeting using several calls to fprint/fputc, and on busy servers this could
1607 cause it to be split over more than one packet - which caused CC:Mail to fall
1608 over when it got the second part of the greeting after sending its first
1609 command. Sigh. To try to avoid this, build the complete greeting message
1610 first, and output it in one fell swoop. This gives a better chance of it
1611 ending up as a single packet. */
1613 ss = store_get(size);
1617 do /* At least once, in case we have an empty string */
1620 uschar *linebreak = Ustrchr(p, '\n');
1621 if (linebreak == NULL)
1624 ss = string_cat(ss, &size, &ptr, US"220 ", 4);
1628 len = linebreak - p;
1629 ss = string_cat(ss, &size, &ptr, US"220-", 4);
1631 ss = string_cat(ss, &size, &ptr, p, len);
1632 ss = string_cat(ss, &size, &ptr, US"\r\n", 2);
1634 if (linebreak != NULL) p++;
1638 ss[ptr] = 0; /* string_cat leaves room for this */
1640 /* Before we write the banner, check that there is no input pending, unless
1641 this synchronisation check is disabled. */
1643 if (smtp_enforce_sync && sender_host_address != NULL && !sender_host_notsocket)
1646 struct timeval tzero;
1650 FD_SET(fileno(smtp_in), &fds);
1651 if (select(fileno(smtp_in) + 1, (SELECT_ARG2_TYPE *)&fds, NULL, NULL,
1654 int rc = read(fileno(smtp_in), smtp_inbuffer, in_buffer_size);
1657 if (rc > 150) rc = 150;
1658 smtp_inbuffer[rc] = 0;
1659 log_write(0, LOG_MAIN|LOG_REJECT, "SMTP protocol "
1660 "synchronization error (input sent without waiting for greeting): "
1661 "rejected connection from %s input=\"%s\"", host_and_ident(TRUE),
1662 string_printing(smtp_inbuffer));
1663 smtp_printf("554 SMTP synchronization error\r\n");
1669 /* Now output the banner */
1671 smtp_printf("%s", ss);
1679 /*************************************************
1680 * Handle SMTP syntax and protocol errors *
1681 *************************************************/
1683 /* Write to the log for SMTP syntax errors in incoming commands, if configured
1684 to do so. Then transmit the error response. The return value depends on the
1685 number of syntax and protocol errors in this SMTP session.
1688 type error type, given as a log flag bit
1689 code response code; <= 0 means don't send a response
1690 data data to reflect in the response (can be NULL)
1691 errmess the error message
1693 Returns: -1 limit of syntax/protocol errors NOT exceeded
1694 +1 limit of syntax/protocol errors IS exceeded
1696 These values fit in with the values of the "done" variable in the main
1697 processing loop in smtp_setup_msg(). */
1700 synprot_error(int type, int code, uschar *data, uschar *errmess)
1704 log_write(type, LOG_MAIN, "SMTP %s error in \"%s\" %s %s",
1705 (type == L_smtp_syntax_error)? "syntax" : "protocol",
1706 string_printing(smtp_cmd_buffer), host_and_ident(TRUE), errmess);
1708 if (++synprot_error_count > smtp_max_synprot_errors)
1711 log_write(0, LOG_MAIN|LOG_REJECT, "SMTP call from %s dropped: too many "
1712 "syntax or protocol errors (last command was \"%s\")",
1713 host_and_ident(FALSE), smtp_cmd_buffer);
1718 smtp_printf("%d%c%s%s%s\r\n", code, (yield == 1)? '-' : ' ',
1719 (data == NULL)? US"" : data, (data == NULL)? US"" : US": ", errmess);
1721 smtp_printf("%d Too many syntax or protocol errors\r\n", code);
1730 /*************************************************
1731 * Log incomplete transactions *
1732 *************************************************/
1734 /* This function is called after a transaction has been aborted by RSET, QUIT,
1735 connection drops or other errors. It logs the envelope information received
1736 so far in order to preserve address verification attempts.
1738 Argument: string to indicate what aborted the transaction
1743 incomplete_transaction_log(uschar *what)
1745 if (sender_address == NULL || /* No transaction in progress */
1746 (log_write_selector & L_smtp_incomplete_transaction) == 0 /* Not logging */
1749 /* Build list of recipients for logging */
1751 if (recipients_count > 0)
1754 raw_recipients = store_get(recipients_count * sizeof(uschar *));
1755 for (i = 0; i < recipients_count; i++)
1756 raw_recipients[i] = recipients_list[i].address;
1757 raw_recipients_count = recipients_count;
1760 log_write(L_smtp_incomplete_transaction, LOG_MAIN|LOG_SENDER|LOG_RECIPIENTS,
1761 "%s incomplete transaction (%s)", host_and_ident(TRUE), what);
1767 /*************************************************
1768 * Send SMTP response, possibly multiline *
1769 *************************************************/
1771 /* There are, it seems, broken clients out there that cannot handle multiline
1772 responses. If no_multiline_responses is TRUE (it can be set from an ACL), we
1773 output nothing for non-final calls, and only the first line for anything else.
1776 code SMTP code, may involve extended status codes
1777 codelen length of smtp code; uf > 3 there's an ESC
1778 final FALSE if the last line isn't the final line
1779 msg message text, possibly containing newlines
1785 smtp_respond(uschar* code, int codelen, BOOL final, uschar *msg)
1790 if (!final && no_multiline_responses) return;
1795 esclen = codelen - 4;
1800 uschar *nl = Ustrchr(msg, '\n');
1803 smtp_printf("%.3s%c%.*s%s\r\n", code, final? ' ':'-', esclen, esc, msg);
1806 else if (nl[1] == 0 || no_multiline_responses)
1808 smtp_printf("%.3s%c%.*s%.*s\r\n", code, final? ' ':'-', esclen, esc,
1809 (int)(nl - msg), msg);
1814 smtp_printf("%.3s-%.*s%.*s\r\n", code, esclen, esc, (int)(nl - msg), msg);
1816 while (isspace(*msg)) msg++;
1824 /*************************************************
1825 * Handle an ACL failure *
1826 *************************************************/
1828 /* This function is called when acl_check() fails. As well as calls from within
1829 this module, it is called from receive.c for an ACL after DATA. It sorts out
1830 logging the incident, and sets up the error response. A message containing
1831 newlines is turned into a multiline SMTP response, but for logging, only the
1834 There's a table of default permanent failure response codes to use in
1835 globals.c, along with the table of names. VFRY is special. Despite RFC1123 it
1836 defaults disabled in Exim. However, discussion in connection with RFC 821bis
1837 (aka RFC 2821) has concluded that the response should be 252 in the disabled
1838 state, because there are broken clients that try VRFY before RCPT. A 5xx
1839 response should be given only when the address is positively known to be
1840 undeliverable. Sigh. Also, for ETRN, 458 is given on refusal, and for AUTH,
1843 From Exim 4.63, it is possible to override the response code details by
1844 providing a suitable response code string at the start of the message provided
1845 in user_msg. The code's first digit is checked for validity.
1848 where where the ACL was called from
1850 user_msg a message that can be included in an SMTP response
1851 log_msg a message for logging
1853 Returns: 0 in most cases
1854 2 if the failure code was FAIL_DROP, in which case the
1855 SMTP connection should be dropped (this value fits with the
1856 "done" variable in smtp_setup_msg() below)
1860 smtp_handle_acl_fail(int where, int rc, uschar *user_msg, uschar *log_msg)
1862 BOOL drop = rc == FAIL_DROP;
1867 uschar *sender_info = US"";
1869 #ifdef WITH_CONTENT_SCAN
1870 (where == ACL_WHERE_MIME)? US"during MIME ACL checks" :
1872 (where == ACL_WHERE_PREDATA)? US"DATA" :
1873 (where == ACL_WHERE_DATA)? US"after DATA" :
1874 (smtp_cmd_argument == NULL)?
1875 string_sprintf("%s in \"connect\" ACL", acl_wherenames[where]) :
1876 string_sprintf("%s %s", acl_wherenames[where], smtp_cmd_argument);
1878 if (drop) rc = FAIL;
1880 /* Set the default SMTP code */
1882 smtp_code = (rc != FAIL)? US"451" : acl_wherecodes[where];
1884 /* Check a user message for starting with a response code and optionally an
1885 extended status code. If found, check that the first digit is valid, and if so,
1886 use it instead of the default code. */
1888 if (user_msg != NULL)
1890 int n = pcre_exec(regex_smtp_code, NULL, CS user_msg, Ustrlen(user_msg), 0,
1891 PCRE_EOPT, ovector, sizeof(ovector)/sizeof(int));
1894 if (user_msg[0] != smtp_code[0])
1896 log_write(0, LOG_MAIN|LOG_PANIC, "configured error code starts with "
1897 "incorrect digit (expected %c) in \"%s\"", smtp_code[0], user_msg);
1899 /* If log_msg == user_msg (the default set in acl.c if no log message is
1900 specified, we must adjust the log message to show the code that is
1901 actually going to be used. */
1903 if (log_msg == user_msg)
1904 log_msg = string_sprintf("%s %s", smtp_code, log_msg + ovector[1]);
1908 smtp_code = user_msg;
1909 codelen = ovector[1]; /* Includes final space */
1911 user_msg += ovector[1]; /* Chop the code off the message */
1915 /* We used to have sender_address here; however, there was a bug that was not
1916 updating sender_address after a rewrite during a verify. When this bug was
1917 fixed, sender_address at this point became the rewritten address. I'm not sure
1918 this is what should be logged, so I've changed to logging the unrewritten
1919 address to retain backward compatibility. */
1921 #ifndef WITH_CONTENT_SCAN
1922 if (where == ACL_WHERE_RCPT || where == ACL_WHERE_DATA)
1924 if (where == ACL_WHERE_RCPT || where == ACL_WHERE_DATA || where == ACL_WHERE_MIME)
1927 sender_info = string_sprintf("F=<%s> ", (sender_address_unrewritten != NULL)?
1928 sender_address_unrewritten : sender_address);
1931 /* If there's been a sender verification failure with a specific message, and
1932 we have not sent a response about it yet, do so now, as a preliminary line for
1933 failures, but not defers. However, always log it for defer, and log it for fail
1934 unless the sender_verify_fail log selector has been turned off. */
1936 if (sender_verified_failed != NULL &&
1937 !testflag(sender_verified_failed, af_sverify_told))
1939 setflag(sender_verified_failed, af_sverify_told);
1941 if (rc != FAIL || (log_extra_selector & LX_sender_verify_fail) != 0)
1942 log_write(0, LOG_MAIN|LOG_REJECT, "%s sender verify %s for <%s>%s",
1943 host_and_ident(TRUE),
1944 ((sender_verified_failed->special_action & 255) == DEFER)? "defer":"fail",
1945 sender_verified_failed->address,
1946 (sender_verified_failed->message == NULL)? US"" :
1947 string_sprintf(": %s", sender_verified_failed->message));
1949 if (rc == FAIL && sender_verified_failed->user_message != NULL)
1950 smtp_respond(smtp_code, codelen, FALSE, string_sprintf(
1951 testflag(sender_verified_failed, af_verify_pmfail)?
1952 "Postmaster verification failed while checking <%s>\n%s\n"
1953 "Several RFCs state that you are required to have a postmaster\n"
1954 "mailbox for each mail domain. This host does not accept mail\n"
1955 "from domains whose servers reject the postmaster address."
1957 testflag(sender_verified_failed, af_verify_nsfail)?
1958 "Callback setup failed while verifying <%s>\n%s\n"
1959 "The initial connection, or a HELO or MAIL FROM:<> command was\n"
1960 "rejected. Refusing MAIL FROM:<> does not help fight spam, disregards\n"
1961 "RFC requirements, and stops you from receiving standard bounce\n"
1962 "messages. This host does not accept mail from domains whose servers\n"
1965 "Verification failed for <%s>\n%s",
1966 sender_verified_failed->address,
1967 sender_verified_failed->user_message));
1970 /* Sort out text for logging */
1972 log_msg = (log_msg == NULL)? US"" : string_sprintf(": %s", log_msg);
1973 lognl = Ustrchr(log_msg, '\n');
1974 if (lognl != NULL) *lognl = 0;
1976 /* Send permanent failure response to the command, but the code used isn't
1977 always a 5xx one - see comments at the start of this function. If the original
1978 rc was FAIL_DROP we drop the connection and yield 2. */
1980 if (rc == FAIL) smtp_respond(smtp_code, codelen, TRUE, (user_msg == NULL)?
1981 US"Administrative prohibition" : user_msg);
1983 /* Send temporary failure response to the command. Don't give any details,
1984 unless acl_temp_details is set. This is TRUE for a callout defer, a "defer"
1985 verb, and for a header verify when smtp_return_error_details is set.
1987 This conditional logic is all somewhat of a mess because of the odd
1988 interactions between temp_details and return_error_details. One day it should
1989 be re-implemented in a tidier fashion. */
1993 if (acl_temp_details && user_msg != NULL)
1995 if (smtp_return_error_details &&
1996 sender_verified_failed != NULL &&
1997 sender_verified_failed->message != NULL)
1999 smtp_respond(smtp_code, codelen, FALSE, sender_verified_failed->message);
2001 smtp_respond(smtp_code, codelen, TRUE, user_msg);
2004 smtp_respond(smtp_code, codelen, TRUE,
2005 US"Temporary local problem - please try later");
2008 /* Log the incident. If the connection is not forcibly to be dropped, return 0.
2009 Otherwise, log why it is closing if required and return 2. */
2011 log_write(0, LOG_MAIN|LOG_REJECT, "%s %s%srejected %s%s",
2012 host_and_ident(TRUE),
2013 sender_info, (rc == FAIL)? US"" : US"temporarily ", what, log_msg);
2015 if (!drop) return 0;
2017 log_write(L_smtp_connection, LOG_MAIN, "%s closed by DROP in ACL",
2018 smtp_get_connection_info());
2025 /*************************************************
2026 * Verify HELO argument *
2027 *************************************************/
2029 /* This function is called if helo_verify_hosts or helo_try_verify_hosts is
2030 matched. It is also called from ACL processing if verify = helo is used and
2031 verification was not previously tried (i.e. helo_try_verify_hosts was not
2032 matched). The result of its processing is to set helo_verified and
2033 helo_verify_failed. These variables should both be FALSE for this function to
2036 Note that EHLO/HELO is legitimately allowed to quote an address literal. Allow
2037 for IPv6 ::ffff: literals.
2040 Returns: TRUE if testing was completed;
2041 FALSE on a temporary failure
2045 smtp_verify_helo(void)
2049 HDEBUG(D_receive) debug_printf("verifying EHLO/HELO argument \"%s\"\n",
2052 if (sender_helo_name == NULL)
2054 HDEBUG(D_receive) debug_printf("no EHLO/HELO command was issued\n");
2057 else if (sender_helo_name[0] == '[')
2059 helo_verified = Ustrncmp(sender_helo_name+1, sender_host_address,
2060 Ustrlen(sender_host_address)) == 0;
2065 if (strncmpic(sender_host_address, US"::ffff:", 7) == 0)
2066 helo_verified = Ustrncmp(sender_helo_name + 1,
2067 sender_host_address + 7, Ustrlen(sender_host_address) - 7) == 0;
2072 { if (helo_verified) debug_printf("matched host address\n"); }
2075 /* Do a reverse lookup if one hasn't already given a positive or negative
2076 response. If that fails, or the name doesn't match, try checking with a forward
2081 if (sender_host_name == NULL && !host_lookup_failed)
2082 yield = host_name_lookup() != DEFER;
2084 /* If a host name is known, check it and all its aliases. */
2086 if (sender_host_name != NULL)
2088 helo_verified = strcmpic(sender_host_name, sender_helo_name) == 0;
2092 HDEBUG(D_receive) debug_printf("matched host name\n");
2096 uschar **aliases = sender_host_aliases;
2097 while (*aliases != NULL)
2099 helo_verified = strcmpic(*aliases++, sender_helo_name) == 0;
2100 if (helo_verified) break;
2105 debug_printf("matched alias %s\n", *(--aliases));
2110 /* Final attempt: try a forward lookup of the helo name */
2116 h.name = sender_helo_name;
2120 HDEBUG(D_receive) debug_printf("getting IP address for %s\n",
2122 rc = host_find_byname(&h, NULL, NULL, TRUE);
2123 if (rc == HOST_FOUND || rc == HOST_FOUND_LOCAL)
2128 if (Ustrcmp(hh->address, sender_host_address) == 0)
2130 helo_verified = TRUE;
2132 debug_printf("IP address for %s matches calling address\n",
2142 if (!helo_verified) helo_verify_failed = FALSE; /* We've tried ... */
2149 /*************************************************
2150 * Initialize for SMTP incoming message *
2151 *************************************************/
2153 /* This function conducts the initial dialogue at the start of an incoming SMTP
2154 message, and builds a list of recipients. However, if the incoming message
2155 is part of a batch (-bS option) a separate function is called since it would
2156 be messy having tests splattered about all over this function. This function
2157 therefore handles the case where interaction is occurring. The input and output
2158 files are set up in smtp_in and smtp_out.
2160 The global recipients_list is set to point to a vector of recipient_item
2161 blocks, whose number is given by recipients_count. This is extended by the
2162 receive_add_recipient() function. The global variable sender_address is set to
2163 the sender's address. The yield is +1 if a message has been successfully
2164 started, 0 if a QUIT command was encountered or the connection was refused from
2165 the particular host, or -1 if the connection was lost.
2169 Returns: > 0 message successfully started (reached DATA)
2170 = 0 QUIT read or end of file reached or call refused
2175 smtp_setup_msg(void)
2178 BOOL toomany = FALSE;
2179 BOOL discarded = FALSE;
2180 BOOL last_was_rej_mail = FALSE;
2181 BOOL last_was_rcpt = FALSE;
2182 void *reset_point = store_get(0);
2184 DEBUG(D_receive) debug_printf("smtp_setup_msg entered\n");
2186 /* Reset for start of new message. We allow one RSET not to be counted as a
2187 nonmail command, for those MTAs that insist on sending it between every
2188 message. Ditto for EHLO/HELO and for STARTTLS, to allow for going in and out of
2189 TLS between messages (an Exim client may do this if it has messages queued up
2190 for the host). Note: we do NOT reset AUTH at this point. */
2192 smtp_reset(reset_point);
2193 message_ended = END_NOTSTARTED;
2195 cmd_list[CMD_LIST_RSET].is_mail_cmd = TRUE;
2196 cmd_list[CMD_LIST_HELO].is_mail_cmd = TRUE;
2197 cmd_list[CMD_LIST_EHLO].is_mail_cmd = TRUE;
2199 cmd_list[CMD_LIST_STARTTLS].is_mail_cmd = TRUE;
2202 /* Set the local signal handler for SIGTERM - it tries to end off tidily */
2204 os_non_restarting_signal(SIGTERM, command_sigterm_handler);
2206 /* Batched SMTP is handled in a different function. */
2208 if (smtp_batched_input) return smtp_setup_batch_msg();
2210 /* Deal with SMTP commands. This loop is exited by setting done to a POSITIVE
2211 value. The values are 2 larger than the required yield of the function. */
2216 uschar *etrn_command;
2217 uschar *etrn_serialize_key;
2219 uschar *user_msg, *log_msg;
2220 uschar *recipient = NULL;
2221 uschar *hello = NULL;
2222 uschar *set_id = NULL;
2224 BOOL was_rej_mail = FALSE;
2225 BOOL was_rcpt = FALSE;
2226 void (*oldsignal)(int);
2228 int start, end, sender_domain, recipient_domain;
2233 switch(smtp_read_command(TRUE))
2235 /* The AUTH command is not permitted to occur inside a transaction, and may
2236 occur successfully only once per connection. Actually, that isn't quite
2237 true. When TLS is started, all previous information about a connection must
2238 be discarded, so a new AUTH is permitted at that time.
2240 AUTH may only be used when it has been advertised. However, it seems that
2241 there are clients that send AUTH when it hasn't been advertised, some of
2242 them even doing this after HELO. And there are MTAs that accept this. Sigh.
2243 So there's a get-out that allows this to happen.
2245 AUTH is initially labelled as a "nonmail command" so that one occurrence
2246 doesn't get counted. We change the label here so that multiple failing
2247 AUTHS will eventually hit the nonmail threshold. */
2250 authentication_failed = TRUE;
2251 cmd_list[CMD_LIST_AUTH].is_mail_cmd = FALSE;
2253 if (!auth_advertised && !allow_auth_unadvertised)
2255 done = synprot_error(L_smtp_protocol_error, 503, NULL,
2256 US"AUTH command used when not advertised");
2259 if (sender_host_authenticated != NULL)
2261 done = synprot_error(L_smtp_protocol_error, 503, NULL,
2262 US"already authenticated");
2265 if (sender_address != NULL)
2267 done = synprot_error(L_smtp_protocol_error, 503, NULL,
2268 US"not permitted in mail transaction");
2274 if (acl_smtp_auth != NULL)
2276 rc = acl_check(ACL_WHERE_AUTH, NULL, acl_smtp_auth, &user_msg, &log_msg);
2279 done = smtp_handle_acl_fail(ACL_WHERE_AUTH, rc, user_msg, log_msg);
2284 /* Find the name of the requested authentication mechanism. */
2286 s = smtp_cmd_argument;
2287 while ((c = *smtp_cmd_argument) != 0 && !isspace(c))
2289 if (!isalnum(c) && c != '-' && c != '_')
2291 done = synprot_error(L_smtp_syntax_error, 501, NULL,
2292 US"invalid character in authentication mechanism name");
2295 smtp_cmd_argument++;
2298 /* If not at the end of the line, we must be at white space. Terminate the
2299 name and move the pointer on to any data that may be present. */
2301 if (*smtp_cmd_argument != 0)
2303 *smtp_cmd_argument++ = 0;
2304 while (isspace(*smtp_cmd_argument)) smtp_cmd_argument++;
2307 /* Search for an authentication mechanism which is configured for use
2308 as a server and which has been advertised (unless, sigh, allow_auth_
2309 unadvertised is set). */
2311 for (au = auths; au != NULL; au = au->next)
2313 if (strcmpic(s, au->public_name) == 0 && au->server &&
2314 (au->advertised || allow_auth_unadvertised)) break;
2319 done = synprot_error(L_smtp_protocol_error, 504, NULL,
2320 string_sprintf("%s authentication mechanism not supported", s));
2324 /* Run the checking code, passing the remainder of the command line as
2325 data. Initials the $auth<n> variables as empty. Initialize $0 empty and set
2326 it as the only set numerical variable. The authenticator may set $auth<n>
2327 and also set other numeric variables. The $auth<n> variables are preferred
2328 nowadays; the numerical variables remain for backwards compatibility.
2330 Afterwards, have a go at expanding the set_id string, even if
2331 authentication failed - for bad passwords it can be useful to log the
2332 userid. On success, require set_id to expand and exist, and put it in
2333 authenticated_id. Save this in permanent store, as the working store gets
2334 reset at HELO, RSET, etc. */
2336 for (i = 0; i < AUTH_VARS; i++) auth_vars[i] = NULL;
2338 expand_nlength[0] = 0; /* $0 contains nothing */
2340 c = (au->info->servercode)(au, smtp_cmd_argument);
2341 if (au->set_id != NULL) set_id = expand_string(au->set_id);
2342 expand_nmax = -1; /* Reset numeric variables */
2343 for (i = 0; i < AUTH_VARS; i++) auth_vars[i] = NULL; /* Reset $auth<n> */
2345 /* The value of authenticated_id is stored in the spool file and printed in
2346 log lines. It must not contain binary zeros or newline characters. In
2347 normal use, it never will, but when playing around or testing, this error
2348 can (did) happen. To guard against this, ensure that the id contains only
2349 printing characters. */
2351 if (set_id != NULL) set_id = string_printing(set_id);
2353 /* For the non-OK cases, set up additional logging data if set_id
2358 if (set_id != NULL && *set_id != 0)
2359 set_id = string_sprintf(" (set_id=%s)", set_id);
2363 /* Switch on the result */
2368 if (au->set_id == NULL || set_id != NULL) /* Complete success */
2370 if (set_id != NULL) authenticated_id = string_copy_malloc(set_id);
2371 sender_host_authenticated = au->name;
2372 authentication_failed = FALSE;
2374 protocols[pextend + pauthed + ((tls_active >= 0)? pcrpted:0)] +
2375 ((sender_host_address != NULL)? pnlocal : 0);
2376 s = ss = US"235 Authentication succeeded";
2377 authenticated_by = au;
2381 /* Authentication succeeded, but we failed to expand the set_id string.
2382 Treat this as a temporary error. */
2384 auth_defer_msg = expand_string_message;
2388 s = string_sprintf("435 Unable to authenticate at present%s",
2389 auth_defer_user_msg);
2390 ss = string_sprintf("435 Unable to authenticate at present%s: %s",
2391 set_id, auth_defer_msg);
2395 s = ss = US"501 Invalid base64 data";
2399 s = ss = US"501 Authentication cancelled";
2403 s = ss = US"553 Initial data not expected";
2407 s = US"535 Incorrect authentication data";
2408 ss = string_sprintf("535 Incorrect authentication data%s", set_id);
2412 s = US"435 Internal error";
2413 ss = string_sprintf("435 Internal error%s: return %d from authentication "
2414 "check", set_id, c);
2418 smtp_printf("%s\r\n", s);
2420 log_write(0, LOG_MAIN|LOG_REJECT, "%s authenticator failed for %s: %s",
2421 au->name, host_and_ident(FALSE), ss);
2423 break; /* AUTH_CMD */
2425 /* The HELO/EHLO commands are permitted to appear in the middle of a
2426 session as well as at the beginning. They have the effect of a reset in
2427 addition to their other functions. Their absence at the start cannot be
2428 taken to be an error.
2432 If the EHLO command is not acceptable to the SMTP server, 501, 500,
2433 or 502 failure replies MUST be returned as appropriate. The SMTP
2434 server MUST stay in the same state after transmitting these replies
2435 that it was in before the EHLO was received.
2437 Therefore, we do not do the reset until after checking the command for
2438 acceptability. This change was made for Exim release 4.11. Previously
2439 it did the reset first. */
2450 HELO_EHLO: /* Common code for HELO and EHLO */
2451 cmd_list[CMD_LIST_HELO].is_mail_cmd = FALSE;
2452 cmd_list[CMD_LIST_EHLO].is_mail_cmd = FALSE;
2454 /* Reject the HELO if its argument was invalid or non-existent. A
2455 successful check causes the argument to be saved in malloc store. */
2457 if (!check_helo(smtp_cmd_argument))
2459 smtp_printf("501 Syntactically invalid %s argument(s)\r\n", hello);
2461 log_write(0, LOG_MAIN|LOG_REJECT, "rejected %s from %s: syntactically "
2462 "invalid argument(s): %s", hello, host_and_ident(FALSE),
2463 (*smtp_cmd_argument == 0)? US"(no argument given)" :
2464 string_printing(smtp_cmd_argument));
2466 if (++synprot_error_count > smtp_max_synprot_errors)
2468 log_write(0, LOG_MAIN|LOG_REJECT, "SMTP call from %s dropped: too many "
2469 "syntax or protocol errors (last command was \"%s\")",
2470 host_and_ident(FALSE), smtp_cmd_buffer);
2477 /* If sender_host_unknown is true, we have got here via the -bs interface,
2478 not called from inetd. Otherwise, we are running an IP connection and the
2479 host address will be set. If the helo name is the primary name of this
2480 host and we haven't done a reverse lookup, force one now. If helo_required
2481 is set, ensure that the HELO name matches the actual host. If helo_verify
2482 is set, do the same check, but softly. */
2484 if (!sender_host_unknown)
2486 BOOL old_helo_verified = helo_verified;
2487 uschar *p = smtp_cmd_argument;
2489 while (*p != 0 && !isspace(*p)) { *p = tolower(*p); p++; }
2492 /* Force a reverse lookup if HELO quoted something in helo_lookup_domains
2493 because otherwise the log can be confusing. */
2495 if (sender_host_name == NULL &&
2496 (deliver_domain = sender_helo_name, /* set $domain */
2497 match_isinlist(sender_helo_name, &helo_lookup_domains, 0,
2498 &domainlist_anchor, NULL, MCL_DOMAIN, TRUE, NULL)) == OK)
2499 (void)host_name_lookup();
2501 /* Rebuild the fullhost info to include the HELO name (and the real name
2502 if it was looked up.) */
2504 host_build_sender_fullhost(); /* Rebuild */
2505 set_process_info("handling%s incoming connection from %s",
2506 (tls_active >= 0)? " TLS" : "", host_and_ident(FALSE));
2508 /* Verify if configured. This doesn't give much security, but it does
2509 make some people happy to be able to do it. If helo_required is set,
2510 (host matches helo_verify_hosts) failure forces rejection. If helo_verify
2511 is set (host matches helo_try_verify_hosts), it does not. This is perhaps
2512 now obsolescent, since the verification can now be requested selectively
2515 helo_verified = helo_verify_failed = FALSE;
2516 if (helo_required || helo_verify)
2518 BOOL tempfail = !smtp_verify_helo();
2523 smtp_printf("%d %s argument does not match calling host\r\n",
2524 tempfail? 451 : 550, hello);
2525 log_write(0, LOG_MAIN|LOG_REJECT, "%srejected \"%s %s\" from %s",
2526 tempfail? "temporarily " : "",
2527 hello, sender_helo_name, host_and_ident(FALSE));
2528 helo_verified = old_helo_verified;
2529 break; /* End of HELO/EHLO processing */
2531 HDEBUG(D_all) debug_printf("%s verification failed but host is in "
2532 "helo_try_verify_hosts\n", hello);
2537 #ifdef EXPERIMENTAL_SPF
2538 /* set up SPF context */
2539 spf_init(sender_helo_name, sender_host_address);
2542 /* Apply an ACL check if one is defined */
2544 if (acl_smtp_helo != NULL)
2546 rc = acl_check(ACL_WHERE_HELO, NULL, acl_smtp_helo, &user_msg, &log_msg);
2549 done = smtp_handle_acl_fail(ACL_WHERE_HELO, rc, user_msg, log_msg);
2550 sender_helo_name = NULL;
2551 host_build_sender_fullhost(); /* Rebuild */
2556 /* The EHLO/HELO command is acceptable. Reset the protocol and the state,
2557 abandoning any previous message. */
2559 received_protocol = (esmtp?
2561 ((sender_host_authenticated != NULL)? pauthed : 0) +
2562 ((tls_active >= 0)? pcrpted : 0)]
2564 protocols[pnormal + ((tls_active >= 0)? pcrpted : 0)])
2566 ((sender_host_address != NULL)? pnlocal : 0);
2568 smtp_reset(reset_point);
2571 /* Generate an OK reply, including the ident if present, and also
2572 the IP address if present. Reflecting back the ident is intended
2573 as a deterrent to mail forgers. For maximum efficiency, and also
2574 because some broken systems expect each response to be in a single
2575 packet, arrange that it is sent in one write(). */
2577 auth_advertised = FALSE;
2578 pipelining_advertised = FALSE;
2580 tls_advertised = FALSE;
2583 s = string_sprintf("250 %s Hello %s%s%s",
2584 smtp_active_hostname,
2585 (sender_ident == NULL)? US"" : sender_ident,
2586 (sender_ident == NULL)? US"" : US" at ",
2587 (sender_host_name == NULL)? sender_helo_name : sender_host_name);
2592 if (sender_host_address != NULL)
2594 s = string_cat(s, &size, &ptr, US" [", 2);
2595 s = string_cat(s, &size, &ptr, sender_host_address,
2596 Ustrlen(sender_host_address));
2597 s = string_cat(s, &size, &ptr, US"]", 1);
2600 s = string_cat(s, &size, &ptr, US"\r\n", 2);
2602 /* If we received EHLO, we must create a multiline response which includes
2603 the functions supported. */
2609 /* I'm not entirely happy with this, as an MTA is supposed to check
2610 that it has enough room to accept a message of maximum size before
2611 it sends this. However, there seems little point in not sending it.
2612 The actual size check happens later at MAIL FROM time. By postponing it
2613 till then, VRFY and EXPN can be used after EHLO when space is short. */
2615 if (thismessage_size_limit > 0)
2617 sprintf(CS big_buffer, "250-SIZE %d\r\n", thismessage_size_limit);
2618 s = string_cat(s, &size, &ptr, big_buffer, Ustrlen(big_buffer));
2622 s = string_cat(s, &size, &ptr, US"250-SIZE\r\n", 10);
2625 /* Exim does not do protocol conversion or data conversion. It is 8-bit
2626 clean; if it has an 8-bit character in its hand, it just sends it. It
2627 cannot therefore specify 8BITMIME and remain consistent with the RFCs.
2628 However, some users want this option simply in order to stop MUAs
2629 mangling messages that contain top-bit-set characters. It is therefore
2630 provided as an option. */
2632 if (accept_8bitmime)
2633 s = string_cat(s, &size, &ptr, US"250-8BITMIME\r\n", 14);
2635 /* Advertise ETRN if there's an ACL checking whether a host is
2636 permitted to issue it; a check is made when any host actually tries. */
2638 if (acl_smtp_etrn != NULL)
2640 s = string_cat(s, &size, &ptr, US"250-ETRN\r\n", 10);
2643 /* Advertise EXPN if there's an ACL checking whether a host is
2644 permitted to issue it; a check is made when any host actually tries. */
2646 if (acl_smtp_expn != NULL)
2648 s = string_cat(s, &size, &ptr, US"250-EXPN\r\n", 10);
2651 /* Exim is quite happy with pipelining, so let the other end know that
2652 it is safe to use it, unless advertising is disabled. */
2654 if (verify_check_host(&pipelining_advertise_hosts) == OK)
2656 s = string_cat(s, &size, &ptr, US"250-PIPELINING\r\n", 16);
2657 sync_cmd_limit = NON_SYNC_CMD_PIPELINING;
2658 pipelining_advertised = TRUE;
2661 /* If any server authentication mechanisms are configured, advertise
2662 them if the current host is in auth_advertise_hosts. The problem with
2663 advertising always is that some clients then require users to
2664 authenticate (and aren't configurable otherwise) even though it may not
2665 be necessary (e.g. if the host is in host_accept_relay).
2667 RFC 2222 states that SASL mechanism names contain only upper case
2668 letters, so output the names in upper case, though we actually recognize
2669 them in either case in the AUTH command. */
2673 if (verify_check_host(&auth_advertise_hosts) == OK)
2677 for (au = auths; au != NULL; au = au->next)
2679 if (au->server && (au->advertise_condition == NULL ||
2680 expand_check_condition(au->advertise_condition, au->name,
2681 US"authenticator")))
2686 s = string_cat(s, &size, &ptr, US"250-AUTH", 8);
2688 auth_advertised = TRUE;
2691 s = string_cat(s, &size, &ptr, US" ", 1);
2692 s = string_cat(s, &size, &ptr, au->public_name,
2693 Ustrlen(au->public_name));
2694 while (++saveptr < ptr) s[saveptr] = toupper(s[saveptr]);
2695 au->advertised = TRUE;
2697 else au->advertised = FALSE;
2699 if (!first) s = string_cat(s, &size, &ptr, US"\r\n", 2);
2703 /* Advertise TLS (Transport Level Security) aka SSL (Secure Socket Layer)
2704 if it has been included in the binary, and the host matches
2705 tls_advertise_hosts. We must *not* advertise if we are already in a
2706 secure connection. */
2709 if (tls_active < 0 &&
2710 verify_check_host(&tls_advertise_hosts) != FAIL)
2712 s = string_cat(s, &size, &ptr, US"250-STARTTLS\r\n", 14);
2713 tls_advertised = TRUE;
2717 /* Finish off the multiline reply with one that is always available. */
2719 s = string_cat(s, &size, &ptr, US"250 HELP\r\n", 10);
2722 /* Terminate the string (for debug), write it, and note that HELO/EHLO
2728 if (tls_active >= 0) (void)tls_write(s, ptr); else
2731 (void)fwrite(s, 1, ptr, smtp_out);
2735 while ((cr = Ustrchr(s, '\r')) != NULL) /* lose CRs */
2736 memmove(cr, cr + 1, (ptr--) - (cr - s));
2737 debug_printf("SMTP>> %s", s);
2740 break; /* HELO/EHLO */
2743 /* The MAIL command requires an address as an operand. All we do
2744 here is to parse it for syntactic correctness. The form "<>" is
2745 a special case which converts into an empty string. The start/end
2746 pointers in the original are not used further for this address, as
2747 it is the canonical extracted address which is all that is kept. */
2750 smtp_mailcmd_count++; /* Count for limit and ratelimit */
2751 was_rej_mail = TRUE; /* Reset if accepted */
2753 if (helo_required && !helo_seen)
2755 smtp_printf("503 HELO or EHLO required\r\n");
2756 log_write(0, LOG_MAIN|LOG_REJECT, "rejected MAIL from %s: no "
2757 "HELO/EHLO given", host_and_ident(FALSE));
2761 if (sender_address != NULL)
2763 done = synprot_error(L_smtp_protocol_error, 503, NULL,
2764 US"sender already given");
2768 if (smtp_cmd_argument[0] == 0)
2770 done = synprot_error(L_smtp_protocol_error, 501, NULL,
2771 US"MAIL must have an address operand");
2775 /* Check to see if the limit for messages per connection would be
2776 exceeded by accepting further messages. */
2778 if (smtp_accept_max_per_connection > 0 &&
2779 smtp_mailcmd_count > smtp_accept_max_per_connection)
2781 smtp_printf("421 too many messages in this connection\r\n");
2782 log_write(0, LOG_MAIN|LOG_REJECT, "rejected MAIL command %s: too many "
2783 "messages in one connection", host_and_ident(TRUE));
2787 /* Reset for start of message - even if this is going to fail, we
2788 obviously need to throw away any previous data. */
2790 smtp_reset(reset_point);
2792 sender_data = recipient_data = NULL;
2794 /* Loop, checking for ESMTP additions to the MAIL FROM command. */
2798 uschar *name, *value, *end;
2799 unsigned long int size;
2801 if (!extract_option(&name, &value)) break;
2803 /* Handle SIZE= by reading the value. We don't do the check till later,
2804 in order to be able to log the sender address on failure. */
2806 if (strcmpic(name, US"SIZE") == 0 &&
2807 ((size = (int)Ustrtoul(value, &end, 10)), *end == 0))
2809 if ((size == ULONG_MAX && errno == ERANGE) || size > INT_MAX)
2811 message_size = (int)size;
2814 /* If this session was initiated with EHLO and accept_8bitmime is set,
2815 Exim will have indicated that it supports the BODY=8BITMIME option. In
2816 fact, it does not support this according to the RFCs, in that it does not
2817 take any special action for forwarding messages containing 8-bit
2818 characters. That is why accept_8bitmime is not the default setting, but
2819 some sites want the action that is provided. We recognize both "8BITMIME"
2820 and "7BIT" as body types, but take no action. */
2822 else if (accept_8bitmime && strcmpic(name, US"BODY") == 0 &&
2823 (strcmpic(value, US"8BITMIME") == 0 ||
2824 strcmpic(value, US"7BIT") == 0)) {}
2826 /* Handle the AUTH extension. If the value given is not "<>" and either
2827 the ACL says "yes" or there is no ACL but the sending host is
2828 authenticated, we set it up as the authenticated sender. However, if the
2829 authenticator set a condition to be tested, we ignore AUTH on MAIL unless
2830 the condition is met. The value of AUTH is an xtext, which means that +,
2831 = and cntrl chars are coded in hex; however "<>" is unaffected by this
2834 else if (strcmpic(name, US"AUTH") == 0)
2836 if (Ustrcmp(value, "<>") != 0)
2841 if (auth_xtextdecode(value, &authenticated_sender) < 0)
2843 /* Put back terminator overrides for error message */
2846 done = synprot_error(L_smtp_syntax_error, 501, NULL,
2847 US"invalid data for AUTH");
2851 if (acl_smtp_mailauth == NULL)
2853 ignore_msg = US"client not authenticated";
2854 rc = (sender_host_authenticated != NULL)? OK : FAIL;
2858 ignore_msg = US"rejected by ACL";
2859 rc = acl_check(ACL_WHERE_MAILAUTH, NULL, acl_smtp_mailauth,
2860 &user_msg, &log_msg);
2866 if (authenticated_by == NULL ||
2867 authenticated_by->mail_auth_condition == NULL ||
2868 expand_check_condition(authenticated_by->mail_auth_condition,
2869 authenticated_by->name, US"authenticator"))
2870 break; /* Accept the AUTH */
2872 ignore_msg = US"server_mail_auth_condition failed";
2873 if (authenticated_id != NULL)
2874 ignore_msg = string_sprintf("%s: authenticated ID=\"%s\"",
2875 ignore_msg, authenticated_id);
2880 authenticated_sender = NULL;
2881 log_write(0, LOG_MAIN, "ignoring AUTH=%s from %s (%s)",
2882 value, host_and_ident(TRUE), ignore_msg);
2885 /* Should only get DEFER or ERROR here. Put back terminator
2886 overrides for error message */
2891 (void)smtp_handle_acl_fail(ACL_WHERE_MAILAUTH, rc, user_msg,
2898 /* Unknown option. Stick back the terminator characters and break
2899 the loop. An error for a malformed address will occur. */
2909 /* If we have passed the threshold for rate limiting, apply the current
2910 delay, and update it for next time, provided this is a limited host. */
2912 if (smtp_mailcmd_count > smtp_rlm_threshold &&
2913 verify_check_host(&smtp_ratelimit_hosts) == OK)
2915 DEBUG(D_receive) debug_printf("rate limit MAIL: delay %.3g sec\n",
2916 smtp_delay_mail/1000.0);
2917 millisleep((int)smtp_delay_mail);
2918 smtp_delay_mail *= smtp_rlm_factor;
2919 if (smtp_delay_mail > (double)smtp_rlm_limit)
2920 smtp_delay_mail = (double)smtp_rlm_limit;
2923 /* Now extract the address, first applying any SMTP-time rewriting. The
2924 TRUE flag allows "<>" as a sender address. */
2926 raw_sender = ((rewrite_existflags & rewrite_smtp) != 0)?
2927 rewrite_one(smtp_cmd_argument, rewrite_smtp, NULL, FALSE, US"",
2928 global_rewrite_rules) : smtp_cmd_argument;
2930 /* rfc821_domains = TRUE; << no longer needed */
2932 parse_extract_address(raw_sender, &errmess, &start, &end, &sender_domain,
2934 /* rfc821_domains = FALSE; << no longer needed */
2936 if (raw_sender == NULL)
2938 done = synprot_error(L_smtp_syntax_error, 501, smtp_cmd_argument, errmess);
2942 sender_address = raw_sender;
2944 /* If there is a configured size limit for mail, check that this message
2945 doesn't exceed it. The check is postponed to this point so that the sender
2948 if (thismessage_size_limit > 0 && message_size > thismessage_size_limit)
2950 smtp_printf("552 Message size exceeds maximum permitted\r\n");
2951 log_write(L_size_reject,
2952 LOG_MAIN|LOG_REJECT, "rejected MAIL FROM:<%s> %s: "
2953 "message too big: size%s=%d max=%d",
2955 host_and_ident(TRUE),
2956 (message_size == INT_MAX)? ">" : "",
2958 thismessage_size_limit);
2959 sender_address = NULL;
2963 /* Check there is enough space on the disk unless configured not to.
2964 When smtp_check_spool_space is set, the check is for thismessage_size_limit
2965 plus the current message - i.e. we accept the message only if it won't
2966 reduce the space below the threshold. Add 5000 to the size to allow for
2967 overheads such as the Received: line and storing of recipients, etc.
2968 By putting the check here, even when SIZE is not given, it allow VRFY
2969 and EXPN etc. to be used when space is short. */
2971 if (!receive_check_fs(
2972 (smtp_check_spool_space && message_size >= 0)?
2973 message_size + 5000 : 0))
2975 smtp_printf("452 Space shortage, please try later\r\n");
2976 sender_address = NULL;
2980 /* If sender_address is unqualified, reject it, unless this is a locally
2981 generated message, or the sending host or net is permitted to send
2982 unqualified addresses - typically local machines behaving as MUAs -
2983 in which case just qualify the address. The flag is set above at the start
2984 of the SMTP connection. */
2986 if (sender_domain == 0 && sender_address[0] != 0)
2988 if (allow_unqualified_sender)
2990 sender_domain = Ustrlen(sender_address) + 1;
2991 sender_address = rewrite_address_qualify(sender_address, FALSE);
2992 DEBUG(D_receive) debug_printf("unqualified address %s accepted\n",
2997 smtp_printf("501 %s: sender address must contain a domain\r\n",
2999 log_write(L_smtp_syntax_error,
3000 LOG_MAIN|LOG_REJECT,
3001 "unqualified sender rejected: <%s> %s%s",
3003 host_and_ident(TRUE),
3005 sender_address = NULL;
3010 /* Apply an ACL check if one is defined, before responding */
3012 rc = (acl_smtp_mail == NULL)? OK :
3013 acl_check(ACL_WHERE_MAIL, NULL, acl_smtp_mail, &user_msg, &log_msg);
3015 if (rc == OK || rc == DISCARD)
3017 smtp_printf("250 OK\r\n");
3018 smtp_delay_rcpt = smtp_rlr_base;
3019 recipients_discarded = (rc == DISCARD);
3020 was_rej_mail = FALSE;
3025 done = smtp_handle_acl_fail(ACL_WHERE_MAIL, rc, user_msg, log_msg);
3026 sender_address = NULL;
3031 /* The RCPT command requires an address as an operand. All we do
3032 here is to parse it for syntactic correctness. There may be any number
3033 of RCPT commands, specifying multiple senders. We build them all into
3034 a data structure that is in argc/argv format. The start/end values
3035 given by parse_extract_address are not used, as we keep only the
3036 extracted address. */
3042 /* There must be a sender address; if the sender was rejected and
3043 pipelining was advertised, we assume the client was pipelining, and do not
3044 count this as a protocol error. Reset was_rej_mail so that further RCPTs
3045 get the same treatment. */
3047 if (sender_address == NULL)
3049 if (pipelining_advertised && last_was_rej_mail)
3051 smtp_printf("503 sender not yet given\r\n");
3052 was_rej_mail = TRUE;
3056 done = synprot_error(L_smtp_protocol_error, 503, NULL,
3057 US"sender not yet given");
3058 was_rcpt = FALSE; /* Not a valid RCPT */
3064 /* Check for an operand */
3066 if (smtp_cmd_argument[0] == 0)
3068 done = synprot_error(L_smtp_syntax_error, 501, NULL,
3069 US"RCPT must have an address operand");
3074 /* Apply SMTP rewriting then extract the working address. Don't allow "<>"
3075 as a recipient address */
3077 recipient = ((rewrite_existflags & rewrite_smtp) != 0)?
3078 rewrite_one(smtp_cmd_argument, rewrite_smtp, NULL, FALSE, US"",
3079 global_rewrite_rules) : smtp_cmd_argument;
3081 /* rfc821_domains = TRUE; << no longer needed */
3082 recipient = parse_extract_address(recipient, &errmess, &start, &end,
3083 &recipient_domain, FALSE);
3084 /* rfc821_domains = FALSE; << no longer needed */
3086 if (recipient == NULL)
3088 done = synprot_error(L_smtp_syntax_error, 501, smtp_cmd_argument, errmess);
3093 /* If the recipient address is unqualified, reject it, unless this is a
3094 locally generated message. However, unqualified addresses are permitted
3095 from a configured list of hosts and nets - typically when behaving as
3096 MUAs rather than MTAs. Sad that SMTP is used for both types of traffic,
3097 really. The flag is set at the start of the SMTP connection.
3099 RFC 1123 talks about supporting "the reserved mailbox postmaster"; I always
3100 assumed this meant "reserved local part", but the revision of RFC 821 and
3101 friends now makes it absolutely clear that it means *mailbox*. Consequently
3102 we must always qualify this address, regardless. */
3104 if (recipient_domain == 0)
3106 if (allow_unqualified_recipient ||
3107 strcmpic(recipient, US"postmaster") == 0)
3109 DEBUG(D_receive) debug_printf("unqualified address %s accepted\n",
3111 recipient_domain = Ustrlen(recipient) + 1;
3112 recipient = rewrite_address_qualify(recipient, TRUE);
3117 smtp_printf("501 %s: recipient address must contain a domain\r\n",
3119 log_write(L_smtp_syntax_error,
3120 LOG_MAIN|LOG_REJECT, "unqualified recipient rejected: "
3121 "<%s> %s%s", recipient, host_and_ident(TRUE),
3127 /* Check maximum allowed */
3129 if (rcpt_count > recipients_max && recipients_max > 0)
3131 if (recipients_max_reject)
3134 smtp_printf("552 too many recipients\r\n");
3136 log_write(0, LOG_MAIN|LOG_REJECT, "too many recipients: message "
3137 "rejected: sender=<%s> %s", sender_address, host_and_ident(TRUE));
3142 smtp_printf("452 too many recipients\r\n");
3144 log_write(0, LOG_MAIN|LOG_REJECT, "too many recipients: excess "
3145 "temporarily rejected: sender=<%s> %s", sender_address,
3146 host_and_ident(TRUE));
3153 /* If we have passed the threshold for rate limiting, apply the current
3154 delay, and update it for next time, provided this is a limited host. */
3156 if (rcpt_count > smtp_rlr_threshold &&
3157 verify_check_host(&smtp_ratelimit_hosts) == OK)
3159 DEBUG(D_receive) debug_printf("rate limit RCPT: delay %.3g sec\n",
3160 smtp_delay_rcpt/1000.0);
3161 millisleep((int)smtp_delay_rcpt);
3162 smtp_delay_rcpt *= smtp_rlr_factor;
3163 if (smtp_delay_rcpt > (double)smtp_rlr_limit)
3164 smtp_delay_rcpt = (double)smtp_rlr_limit;
3167 /* If the MAIL ACL discarded all the recipients, we bypass ACL checking
3168 for them. Otherwise, check the access control list for this recipient. */
3170 rc = recipients_discarded? DISCARD :
3171 acl_check(ACL_WHERE_RCPT, recipient, acl_smtp_rcpt, &user_msg, &log_msg);
3173 /* The ACL was happy */
3177 smtp_printf("250 Accepted\r\n");
3178 receive_add_recipient(recipient, -1);
3181 /* The recipient was discarded */
3183 else if (rc == DISCARD)
3185 smtp_printf("250 Accepted\r\n");
3188 log_write(0, LOG_MAIN|LOG_REJECT, "%s F=<%s> rejected RCPT %s: "
3189 "discarded by %s ACL%s%s", host_and_ident(TRUE),
3190 (sender_address_unrewritten != NULL)?
3191 sender_address_unrewritten : sender_address,
3192 smtp_cmd_argument, recipients_discarded? "MAIL" : "RCPT",
3193 (log_msg == NULL)? US"" : US": ",
3194 (log_msg == NULL)? US"" : log_msg);
3197 /* Either the ACL failed the address, or it was deferred. */
3201 if (rc == FAIL) rcpt_fail_count++; else rcpt_defer_count++;
3202 done = smtp_handle_acl_fail(ACL_WHERE_RCPT, rc, user_msg, log_msg);
3207 /* The DATA command is legal only if it follows successful MAIL FROM
3208 and RCPT TO commands. However, if pipelining is advertised, a bad DATA is
3209 not counted as a protocol error if it follows RCPT (which must have been
3210 rejected if there are no recipients.) This function is complete when a
3211 valid DATA command is encountered.
3213 Note concerning the code used: RFC 2821 says this:
3215 - If there was no MAIL, or no RCPT, command, or all such commands
3216 were rejected, the server MAY return a "command out of sequence"
3217 (503) or "no valid recipients" (554) reply in response to the
3220 The example in the pipelining RFC 2920 uses 554, but I use 503 here
3221 because it is the same whether pipelining is in use or not. */
3224 if (!discarded && recipients_count <= 0)
3226 if (pipelining_advertised && last_was_rcpt)
3227 smtp_printf("503 valid RCPT command must precede DATA\r\n");
3229 done = synprot_error(L_smtp_protocol_error, 503, NULL,
3230 US"valid RCPT command must precede DATA");
3234 if (toomany && recipients_max_reject)
3236 sender_address = NULL; /* This will allow a new MAIL without RSET */
3237 sender_address_unrewritten = NULL;
3238 smtp_printf("554 Too many recipients\r\n");
3242 if (acl_smtp_predata == NULL) rc = OK; else
3244 enable_dollar_recipients = TRUE;
3245 rc = acl_check(ACL_WHERE_PREDATA, NULL, acl_smtp_predata, &user_msg,
3247 enable_dollar_recipients = FALSE;
3252 smtp_printf("354 Enter message, ending with \".\" on a line by itself\r\n");
3254 message_ended = END_NOTENDED; /* Indicate in middle of data */
3257 /* Either the ACL failed the address, or it was deferred. */
3260 done = smtp_handle_acl_fail(ACL_WHERE_PREDATA, rc, user_msg, log_msg);
3266 rc = acl_check(ACL_WHERE_VRFY, NULL, acl_smtp_vrfy, &user_msg, &log_msg);
3268 done = smtp_handle_acl_fail(ACL_WHERE_VRFY, rc, user_msg, log_msg);
3274 /* rfc821_domains = TRUE; << no longer needed */
3275 address = parse_extract_address(smtp_cmd_argument, &errmess, &start, &end,
3276 &recipient_domain, FALSE);
3277 /* rfc821_domains = FALSE; << no longer needed */
3279 if (address == NULL)
3280 s = string_sprintf("501 %s", errmess);
3283 address_item *addr = deliver_make_addr(address, FALSE);
3284 switch(verify_address(addr, NULL, vopt_is_recipient | vopt_qualify, -1,
3285 -1, -1, NULL, NULL, NULL))
3288 s = string_sprintf("250 <%s> is deliverable", address);
3292 s = (addr->user_message != NULL)?
3293 string_sprintf("451 <%s> %s", address, addr->user_message) :
3294 string_sprintf("451 Cannot resolve <%s> at this time", address);
3298 s = (addr->user_message != NULL)?
3299 string_sprintf("550 <%s> %s", address, addr->user_message) :
3300 string_sprintf("550 <%s> is not deliverable", address);
3301 log_write(0, LOG_MAIN, "VRFY failed for %s %s",
3302 smtp_cmd_argument, host_and_ident(TRUE));
3307 smtp_printf("%s\r\n", s);
3313 rc = acl_check(ACL_WHERE_EXPN, NULL, acl_smtp_expn, &user_msg, &log_msg);
3315 done = smtp_handle_acl_fail(ACL_WHERE_EXPN, rc, user_msg, log_msg);
3318 BOOL save_log_testing_mode = log_testing_mode;
3319 address_test_mode = log_testing_mode = TRUE;
3320 (void) verify_address(deliver_make_addr(smtp_cmd_argument, FALSE),
3321 smtp_out, vopt_is_recipient | vopt_qualify | vopt_expn, -1, -1, -1,
3323 address_test_mode = FALSE;
3324 log_testing_mode = save_log_testing_mode; /* true for -bh */
3332 if (!tls_advertised)
3334 done = synprot_error(L_smtp_protocol_error, 503, NULL,
3335 US"STARTTLS command used when not advertised");
3339 /* Apply an ACL check if one is defined */
3341 if (acl_smtp_starttls != NULL)
3343 rc = acl_check(ACL_WHERE_STARTTLS, NULL, acl_smtp_starttls, &user_msg,
3347 done = smtp_handle_acl_fail(ACL_WHERE_STARTTLS, rc, user_msg, log_msg);
3352 /* RFC 2487 is not clear on when this command may be sent, though it
3353 does state that all information previously obtained from the client
3354 must be discarded if a TLS session is started. It seems reasonble to
3355 do an implied RSET when STARTTLS is received. */
3357 incomplete_transaction_log(US"STARTTLS");
3358 smtp_reset(reset_point);
3360 cmd_list[CMD_LIST_STARTTLS].is_mail_cmd = FALSE;
3362 /* Attempt to start up a TLS session, and if successful, discard all
3363 knowledge that was obtained previously. At least, that's what the RFC says,
3364 and that's what happens by default. However, in order to work round YAEB,
3365 there is an option to remember the esmtp state. Sigh.
3367 We must allow for an extra EHLO command and an extra AUTH command after
3368 STARTTLS that don't add to the nonmail command count. */
3370 if ((rc = tls_server_start(tls_require_ciphers)) == OK)
3372 if (!tls_remember_esmtp)
3373 helo_seen = esmtp = auth_advertised = pipelining_advertised = FALSE;
3374 cmd_list[CMD_LIST_EHLO].is_mail_cmd = TRUE;
3375 cmd_list[CMD_LIST_AUTH].is_mail_cmd = TRUE;
3376 if (sender_helo_name != NULL)
3378 store_free(sender_helo_name);
3379 sender_helo_name = NULL;
3380 host_build_sender_fullhost(); /* Rebuild */
3381 set_process_info("handling incoming TLS connection from %s",
3382 host_and_ident(FALSE));
3384 received_protocol = (esmtp?
3385 protocols[pextend + pcrpted +
3386 ((sender_host_authenticated != NULL)? pauthed : 0)]
3388 protocols[pnormal + pcrpted])
3390 ((sender_host_address != NULL)? pnlocal : 0);
3392 sender_host_authenticated = NULL;
3393 authenticated_id = NULL;
3394 sync_cmd_limit = NON_SYNC_CMD_NON_PIPELINING;
3395 DEBUG(D_tls) debug_printf("TLS active\n");
3396 break; /* Successful STARTTLS */
3399 /* Some local configuration problem was discovered before actually trying
3400 to do a TLS handshake; give a temporary error. */
3402 else if (rc == DEFER)
3404 smtp_printf("454 TLS currently unavailable\r\n");
3408 /* Hard failure. Reject everything except QUIT or closed connection. One
3409 cause for failure is a nested STARTTLS, in which case tls_active remains
3410 set, but we must still reject all incoming commands. */
3412 DEBUG(D_tls) debug_printf("TLS failed to start\n");
3415 switch(smtp_read_command(FALSE))
3418 log_write(L_smtp_connection, LOG_MAIN, "%s closed by EOF",
3419 smtp_get_connection_info());
3424 smtp_printf("221 %s closing connection\r\n", smtp_active_hostname);
3425 log_write(L_smtp_connection, LOG_MAIN, "%s closed by QUIT",
3426 smtp_get_connection_info());
3431 smtp_printf("554 Security failure\r\n");
3440 /* The ACL for QUIT is provided for gathering statistical information or
3441 similar; it does not affect the response code, but it can supply a custom
3445 incomplete_transaction_log(US"QUIT");
3447 if (acl_smtp_quit != NULL)
3449 rc = acl_check(ACL_WHERE_QUIT, NULL, acl_smtp_quit,&user_msg,&log_msg);
3451 log_write(0, LOG_MAIN|LOG_PANIC, "ACL for QUIT returned ERROR: %s",
3454 else user_msg = NULL;
3456 if (user_msg == NULL)
3457 smtp_printf("221 %s closing connection\r\n", smtp_active_hostname);
3459 smtp_printf("221 %s\r\n", user_msg);
3466 log_write(L_smtp_connection, LOG_MAIN, "%s closed by QUIT",
3467 smtp_get_connection_info());
3472 incomplete_transaction_log(US"RSET");
3473 smtp_reset(reset_point);
3475 smtp_printf("250 Reset OK\r\n");
3476 cmd_list[CMD_LIST_RSET].is_mail_cmd = FALSE;
3481 smtp_printf("250 OK\r\n");
3485 /* Show ETRN/EXPN/VRFY if there's
3486 an ACL for checking hosts; if actually used, a check will be done for
3490 smtp_printf("214-Commands supported:\r\n");
3494 Ustrcat(buffer, " AUTH");
3496 Ustrcat(buffer, " STARTTLS");
3498 Ustrcat(buffer, " HELO EHLO MAIL RCPT DATA");
3499 Ustrcat(buffer, " NOOP QUIT RSET HELP");
3500 if (acl_smtp_etrn != NULL) Ustrcat(buffer, " ETRN");
3501 if (acl_smtp_expn != NULL) Ustrcat(buffer, " EXPN");
3502 if (acl_smtp_vrfy != NULL) Ustrcat(buffer, " VRFY");
3503 smtp_printf("214%s\r\n", buffer);
3509 incomplete_transaction_log(US"connection lost");
3510 smtp_printf("421 %s lost input connection\r\n", smtp_active_hostname);
3512 /* Don't log by default unless in the middle of a message, as some mailers
3513 just drop the call rather than sending QUIT, and it clutters up the logs.
3516 if (sender_address != NULL || recipients_count > 0)
3517 log_write(L_lost_incoming_connection,
3519 "unexpected %s while reading SMTP command from %s%s",
3520 sender_host_unknown? "EOF" : "disconnection",
3521 host_and_ident(FALSE), smtp_read_error);
3523 else log_write(L_smtp_connection, LOG_MAIN, "%s lost%s",
3524 smtp_get_connection_info(), smtp_read_error);
3531 if (sender_address != NULL)
3533 done = synprot_error(L_smtp_protocol_error, 503, NULL,
3534 US"ETRN is not permitted inside a transaction");
3538 log_write(L_etrn, LOG_MAIN, "ETRN %s received from %s", smtp_cmd_argument,
3539 host_and_ident(FALSE));
3541 rc = acl_check(ACL_WHERE_ETRN, NULL, acl_smtp_etrn, &user_msg, &log_msg);
3544 done = smtp_handle_acl_fail(ACL_WHERE_ETRN, rc, user_msg, log_msg);
3548 /* Compute the serialization key for this command. */
3550 etrn_serialize_key = string_sprintf("etrn-%s\n", smtp_cmd_argument);
3552 /* If a command has been specified for running as a result of ETRN, we
3553 permit any argument to ETRN. If not, only the # standard form is permitted,
3554 since that is strictly the only kind of ETRN that can be implemented
3555 according to the RFC. */
3557 if (smtp_etrn_command != NULL)
3561 etrn_command = smtp_etrn_command;
3562 deliver_domain = smtp_cmd_argument;
3563 rc = transport_set_up_command(&argv, smtp_etrn_command, TRUE, 0, NULL,
3564 US"ETRN processing", &error);
3565 deliver_domain = NULL;
3568 log_write(0, LOG_MAIN|LOG_PANIC, "failed to set up ETRN command: %s",
3570 smtp_printf("458 Internal failure\r\n");
3575 /* Else set up to call Exim with the -R option. */
3579 if (*smtp_cmd_argument++ != '#')
3581 done = synprot_error(L_smtp_syntax_error, 501, NULL,
3582 US"argument must begin with #");
3585 etrn_command = US"exim -R";
3586 argv = child_exec_exim(CEE_RETURN_ARGV, TRUE, NULL, TRUE, 2, US"-R",
3590 /* If we are host-testing, don't actually do anything. */
3596 debug_printf("ETRN command is: %s\n", etrn_command);
3597 debug_printf("ETRN command execution skipped\n");
3599 smtp_printf("250 OK\r\n");
3604 /* If ETRN queue runs are to be serialized, check the database to
3605 ensure one isn't already running. */
3607 if (smtp_etrn_serialize && !enq_start(etrn_serialize_key))
3609 smtp_printf("458 Already processing %s\r\n", smtp_cmd_argument);
3613 /* Fork a child process and run the command. We don't want to have to
3614 wait for the process at any point, so set SIGCHLD to SIG_IGN before
3615 forking. It should be set that way anyway for external incoming SMTP,
3616 but we save and restore to be tidy. If serialization is required, we
3617 actually run the command in yet another process, so we can wait for it
3618 to complete and then remove the serialization lock. */
3620 oldsignal = signal(SIGCHLD, SIG_IGN);
3622 if ((pid = fork()) == 0)
3624 smtp_input = FALSE; /* This process is not associated with the */
3625 (void)fclose(smtp_in); /* SMTP call any more. */
3626 (void)fclose(smtp_out);
3628 signal(SIGCHLD, SIG_DFL); /* Want to catch child */
3630 /* If not serializing, do the exec right away. Otherwise, fork down
3631 into another process. */
3633 if (!smtp_etrn_serialize || (pid = fork()) == 0)
3635 DEBUG(D_exec) debug_print_argv(argv);
3636 exim_nullstd(); /* Ensure std{in,out,err} exist */
3637 execv(CS argv[0], (char *const *)argv);
3638 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "exec of \"%s\" (ETRN) failed: %s",
3639 etrn_command, strerror(errno));
3640 _exit(EXIT_FAILURE); /* paranoia */
3643 /* Obey this if smtp_serialize and the 2nd fork yielded non-zero. That
3644 is, we are in the first subprocess, after forking again. All we can do
3645 for a failing fork is to log it. Otherwise, wait for the 2nd process to
3646 complete, before removing the serialization. */
3649 log_write(0, LOG_MAIN|LOG_PANIC, "2nd fork for serialized ETRN "
3650 "failed: %s", strerror(errno));
3654 DEBUG(D_any) debug_printf("waiting for serialized ETRN process %d\n",
3656 (void)wait(&status);
3657 DEBUG(D_any) debug_printf("serialized ETRN process %d ended\n",
3661 enq_end(etrn_serialize_key);
3662 _exit(EXIT_SUCCESS);
3665 /* Back in the top level SMTP process. Check that we started a subprocess
3666 and restore the signal state. */
3670 log_write(0, LOG_MAIN|LOG_PANIC, "fork of process for ETRN failed: %s",
3672 smtp_printf("458 Unable to fork process\r\n");
3673 if (smtp_etrn_serialize) enq_end(etrn_serialize_key);
3675 else smtp_printf("250 OK\r\n");
3677 signal(SIGCHLD, oldsignal);
3682 done = synprot_error(L_smtp_syntax_error, 501, NULL,
3683 US"unexpected argument data");
3687 /* This currently happens only for NULLs, but could be extended. */
3690 done = synprot_error(L_smtp_syntax_error, 0, NULL, /* Just logs */
3691 US"NULL character(s) present (shown as '?')");
3692 smtp_printf("501 NULL characters are not allowed in SMTP commands\r\n");
3697 if (smtp_inend >= smtp_inbuffer + in_buffer_size)
3698 smtp_inend = smtp_inbuffer + in_buffer_size - 1;
3699 c = smtp_inend - smtp_inptr;
3700 if (c > 150) c = 150;
3702 incomplete_transaction_log(US"sync failure");
3703 log_write(0, LOG_MAIN|LOG_REJECT, "SMTP protocol synchronization error "
3704 "(next input sent too soon: pipelining was%s advertised): "
3705 "rejected \"%s\" %s next input=\"%s\"",
3706 pipelining_advertised? "" : " not",
3707 smtp_cmd_buffer, host_and_ident(TRUE),
3708 string_printing(smtp_inptr));
3709 smtp_printf("554 SMTP synchronization error\r\n");
3710 done = 1; /* Pretend eof - drops connection */
3714 case TOO_MANY_NONMAIL_CMD:
3715 incomplete_transaction_log(US"too many non-mail commands");
3716 log_write(0, LOG_MAIN|LOG_REJECT, "SMTP call from %s dropped: too many "
3717 "nonmail commands (last was \"%.*s\")", host_and_ident(FALSE),
3718 smtp_cmd_argument - smtp_cmd_buffer, smtp_cmd_buffer);
3719 smtp_printf("554 Too many nonmail commands\r\n");
3720 done = 1; /* Pretend eof - drops connection */
3725 if (unknown_command_count++ >= smtp_max_unknown_commands)
3727 log_write(L_smtp_syntax_error, LOG_MAIN,
3728 "SMTP syntax error in \"%s\" %s %s",
3729 string_printing(smtp_cmd_buffer), host_and_ident(TRUE),
3730 US"unrecognized command");
3731 incomplete_transaction_log(US"unrecognized command");
3732 smtp_printf("500 Too many unrecognized commands\r\n");
3734 log_write(0, LOG_MAIN|LOG_REJECT, "SMTP call from %s dropped: too many "
3735 "unrecognized commands (last was \"%s\")", host_and_ident(FALSE),
3739 done = synprot_error(L_smtp_syntax_error, 500, NULL,
3740 US"unrecognized command");
3744 /* This label is used by goto's inside loops that want to break out to
3745 the end of the command-processing loop. */
3748 last_was_rej_mail = was_rej_mail; /* Remember some last commands for */
3749 last_was_rcpt = was_rcpt; /* protocol error handling */
3753 return done - 2; /* Convert yield values */
3756 /* End of smtp_in.c */