1 /* $Cambridge: exim/src/src/smtp_in.c,v 1.46 2006/10/23 10:55:10 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;
796 /*************************************************
797 * Reset for new message *
798 *************************************************/
800 /* This function is called whenever the SMTP session is reset from
801 within either of the setup functions.
803 Argument: the stacking pool storage reset point
808 smtp_reset(void *reset_point)
810 store_reset(reset_point);
811 recipients_list = NULL;
812 rcpt_count = rcpt_defer_count = rcpt_fail_count =
813 raw_recipients_count = recipients_count = recipients_list_max = 0;
814 message_linecount = 0;
816 acl_added_headers = NULL;
817 queue_only_policy = FALSE;
818 deliver_freeze = FALSE; /* Can be set by ACL */
819 freeze_tell = freeze_tell_config; /* Can be set by ACL */
820 fake_response = OK; /* Can be set by ACL */
821 #ifdef WITH_CONTENT_SCAN
822 no_mbox_unspool = FALSE; /* Can be set by ACL */
824 submission_mode = FALSE; /* Can be set by ACL */
825 suppress_local_fixups = FALSE; /* Can be set by ACL */
826 active_local_from_check = local_from_check; /* Can be set by ACL */
827 active_local_sender_retain = local_sender_retain; /* Can be set by ACL */
828 sender_address = NULL;
829 submission_name = NULL; /* Can be set by ACL */
830 raw_sender = NULL; /* After SMTP rewrite, before qualifying */
831 sender_address_unrewritten = NULL; /* Set only after verify rewrite */
832 sender_verified_list = NULL; /* No senders verified */
833 memset(sender_address_cache, 0, sizeof(sender_address_cache));
834 memset(sender_domain_cache, 0, sizeof(sender_domain_cache));
835 authenticated_sender = NULL;
836 #ifdef EXPERIMENTAL_BRIGHTMAIL
840 #ifdef EXPERIMENTAL_DOMAINKEYS
843 #ifdef EXPERIMENTAL_SPF
844 spf_header_comment = NULL;
847 spf_smtp_comment = NULL;
849 body_linecount = body_zerocount = 0;
851 sender_rate = sender_rate_limit = sender_rate_period = NULL;
852 ratelimiters_mail = NULL; /* Updated by ratelimit ACL condition */
853 /* Note that ratelimiters_conn persists across resets. */
855 /* Reset message ACL variables */
859 /* The message body variables use malloc store. They may be set if this is
860 not the first message in an SMTP session and the previous message caused them
861 to be referenced in an ACL. */
863 if (message_body != NULL)
865 store_free(message_body);
869 if (message_body_end != NULL)
871 store_free(message_body_end);
872 message_body_end = NULL;
875 /* Warning log messages are also saved in malloc store. They are saved to avoid
876 repetition in the same message, but it seems right to repeat them for different
879 while (acl_warn_logged != NULL)
881 string_item *this = acl_warn_logged;
882 acl_warn_logged = acl_warn_logged->next;
891 /*************************************************
892 * Initialize for incoming batched SMTP message *
893 *************************************************/
895 /* This function is called from smtp_setup_msg() in the case when
896 smtp_batched_input is true. This happens when -bS is used to pass a whole batch
897 of messages in one file with SMTP commands between them. All errors must be
898 reported by sending a message, and only MAIL FROM, RCPT TO, and DATA are
899 relevant. After an error on a sender, or an invalid recipient, the remainder
900 of the message is skipped. The value of received_protocol is already set.
903 Returns: > 0 message successfully started (reached DATA)
904 = 0 QUIT read or end of file reached
909 smtp_setup_batch_msg(void)
912 void *reset_point = store_get(0);
914 /* Save the line count at the start of each transaction - single commands
915 like HELO and RSET count as whole transactions. */
917 bsmtp_transaction_linecount = receive_linecount;
919 if ((receive_feof)()) return 0; /* Treat EOF as QUIT */
921 smtp_reset(reset_point); /* Reset for start of message */
923 /* Deal with SMTP commands. This loop is exited by setting done to a POSITIVE
924 value. The values are 2 larger than the required yield of the function. */
929 uschar *recipient = NULL;
930 int start, end, sender_domain, recipient_domain;
932 switch(smtp_read_command(FALSE))
934 /* The HELO/EHLO commands set sender_address_helo if they have
935 valid data; otherwise they are ignored, except that they do
936 a reset of the state. */
941 check_helo(smtp_cmd_argument);
945 smtp_reset(reset_point);
946 bsmtp_transaction_linecount = receive_linecount;
950 /* The MAIL FROM command requires an address as an operand. All we
951 do here is to parse it for syntactic correctness. The form "<>" is
952 a special case which converts into an empty string. The start/end
953 pointers in the original are not used further for this address, as
954 it is the canonical extracted address which is all that is kept. */
957 if (sender_address != NULL)
958 /* The function moan_smtp_batch() does not return. */
959 moan_smtp_batch(smtp_cmd_buffer, "503 Sender already given");
961 if (smtp_cmd_argument[0] == 0)
962 /* The function moan_smtp_batch() does not return. */
963 moan_smtp_batch(smtp_cmd_buffer, "501 MAIL FROM must have an address operand");
965 /* Reset to start of message */
967 smtp_reset(reset_point);
969 /* Apply SMTP rewrite */
971 raw_sender = ((rewrite_existflags & rewrite_smtp) != 0)?
972 rewrite_one(smtp_cmd_argument, rewrite_smtp|rewrite_smtp_sender, NULL, FALSE,
973 US"", global_rewrite_rules) : smtp_cmd_argument;
975 /* Extract the address; the TRUE flag allows <> as valid */
978 parse_extract_address(raw_sender, &errmess, &start, &end, &sender_domain,
981 if (raw_sender == NULL)
982 /* The function moan_smtp_batch() does not return. */
983 moan_smtp_batch(smtp_cmd_buffer, "501 %s", errmess);
985 sender_address = string_copy(raw_sender);
987 /* Qualify unqualified sender addresses if permitted to do so. */
989 if (sender_domain == 0 && sender_address[0] != 0 && sender_address[0] != '@')
991 if (allow_unqualified_sender)
993 sender_address = rewrite_address_qualify(sender_address, FALSE);
994 DEBUG(D_receive) debug_printf("unqualified address %s accepted "
995 "and rewritten\n", raw_sender);
997 /* The function moan_smtp_batch() does not return. */
998 else moan_smtp_batch(smtp_cmd_buffer, "501 sender address must contain "
1004 /* The RCPT TO command requires an address as an operand. All we do
1005 here is to parse it for syntactic correctness. There may be any number
1006 of RCPT TO commands, specifying multiple senders. We build them all into
1007 a data structure that is in argc/argv format. The start/end values
1008 given by parse_extract_address are not used, as we keep only the
1009 extracted address. */
1012 if (sender_address == NULL)
1013 /* The function moan_smtp_batch() does not return. */
1014 moan_smtp_batch(smtp_cmd_buffer, "503 No sender yet given");
1016 if (smtp_cmd_argument[0] == 0)
1017 /* The function moan_smtp_batch() does not return. */
1018 moan_smtp_batch(smtp_cmd_buffer, "501 RCPT TO must have an address operand");
1020 /* Check maximum number allowed */
1022 if (recipients_max > 0 && recipients_count + 1 > recipients_max)
1023 /* The function moan_smtp_batch() does not return. */
1024 moan_smtp_batch(smtp_cmd_buffer, "%s too many recipients",
1025 recipients_max_reject? "552": "452");
1027 /* Apply SMTP rewrite, then extract address. Don't allow "<>" as a
1028 recipient address */
1030 recipient = ((rewrite_existflags & rewrite_smtp) != 0)?
1031 rewrite_one(smtp_cmd_argument, rewrite_smtp, NULL, FALSE, US"",
1032 global_rewrite_rules) : smtp_cmd_argument;
1034 /* rfc821_domains = TRUE; << no longer needed */
1035 recipient = parse_extract_address(recipient, &errmess, &start, &end,
1036 &recipient_domain, FALSE);
1037 /* rfc821_domains = FALSE; << no longer needed */
1039 if (recipient == NULL)
1040 /* The function moan_smtp_batch() does not return. */
1041 moan_smtp_batch(smtp_cmd_buffer, "501 %s", errmess);
1043 /* If the recipient address is unqualified, qualify it if permitted. Then
1044 add it to the list of recipients. */
1046 if (recipient_domain == 0)
1048 if (allow_unqualified_recipient)
1050 DEBUG(D_receive) debug_printf("unqualified address %s accepted\n",
1052 recipient = rewrite_address_qualify(recipient, TRUE);
1054 /* The function moan_smtp_batch() does not return. */
1055 else moan_smtp_batch(smtp_cmd_buffer, "501 recipient address must contain "
1058 receive_add_recipient(recipient, -1);
1062 /* The DATA command is legal only if it follows successful MAIL FROM
1063 and RCPT TO commands. This function is complete when a valid DATA
1064 command is encountered. */
1067 if (sender_address == NULL || recipients_count <= 0)
1069 /* The function moan_smtp_batch() does not return. */
1070 if (sender_address == NULL)
1071 moan_smtp_batch(smtp_cmd_buffer,
1072 "503 MAIL FROM:<sender> command must precede DATA");
1074 moan_smtp_batch(smtp_cmd_buffer,
1075 "503 RCPT TO:<recipient> must precede DATA");
1079 done = 3; /* DATA successfully achieved */
1080 message_ended = END_NOTENDED; /* Indicate in middle of message */
1085 /* The VRFY, EXPN, HELP, ETRN, and NOOP commands are ignored. */
1092 bsmtp_transaction_linecount = receive_linecount;
1103 /* The function moan_smtp_batch() does not return. */
1104 moan_smtp_batch(smtp_cmd_buffer, "501 Unexpected argument data");
1109 /* The function moan_smtp_batch() does not return. */
1110 moan_smtp_batch(smtp_cmd_buffer, "501 Unexpected NULL in SMTP command");
1115 /* The function moan_smtp_batch() does not return. */
1116 moan_smtp_batch(smtp_cmd_buffer, "500 Command unrecognized");
1121 return done - 2; /* Convert yield values */
1127 /*************************************************
1128 * Start an SMTP session *
1129 *************************************************/
1131 /* This function is called at the start of an SMTP session. Thereafter,
1132 smtp_setup_msg() is called to initiate each separate message. This
1133 function does host-specific testing, and outputs the banner line.
1136 Returns: FALSE if the session can not continue; something has
1137 gone wrong, or the connection to the host is blocked
1141 smtp_start_session(void)
1147 /* Default values for certain variables */
1149 helo_seen = esmtp = helo_accept_junk = FALSE;
1150 count_nonmail = TRUE_UNSET;
1151 synprot_error_count = unknown_command_count = nonmail_command_count = 0;
1152 smtp_delay_mail = smtp_rlm_base;
1153 auth_advertised = FALSE;
1154 pipelining_advertised = FALSE;
1155 sync_cmd_limit = NON_SYNC_CMD_NON_PIPELINING;
1157 memset(sender_host_cache, 0, sizeof(sender_host_cache));
1159 /* If receiving by -bs from a trusted user, or testing with -bh, we allow
1160 authentication settings from -oMaa to remain in force. */
1162 if (!host_checking && !sender_host_notsocket) sender_host_authenticated = NULL;
1163 authenticated_by = NULL;
1166 tls_cipher = tls_peerdn = NULL;
1167 tls_advertised = FALSE;
1170 /* Reset ACL connection variables */
1174 /* Allow for trailing 0 in the command buffer. */
1176 smtp_cmd_buffer = (uschar *)malloc(smtp_cmd_buffer_size + 1);
1177 if (smtp_cmd_buffer == NULL)
1178 log_write(0, LOG_MAIN|LOG_PANIC_DIE,
1179 "malloc() failed for SMTP command buffer");
1181 /* For batched input, the protocol setting can be overridden from the
1182 command line by a trusted caller. */
1184 if (smtp_batched_input)
1186 if (received_protocol == NULL) received_protocol = US"local-bsmtp";
1189 /* For non-batched SMTP input, the protocol setting is forced here. It will be
1190 reset later if any of EHLO/AUTH/STARTTLS are received. */
1194 protocols[pnormal] + ((sender_host_address != NULL)? pnlocal : 0);
1196 /* Set up the buffer for inputting using direct read() calls, and arrange to
1197 call the local functions instead of the standard C ones. */
1199 smtp_inbuffer = (uschar *)malloc(in_buffer_size);
1200 if (smtp_inbuffer == NULL)
1201 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "malloc() failed for SMTP input buffer");
1202 receive_getc = smtp_getc;
1203 receive_ungetc = smtp_ungetc;
1204 receive_feof = smtp_feof;
1205 receive_ferror = smtp_ferror;
1206 smtp_inptr = smtp_inend = smtp_inbuffer;
1207 smtp_had_eof = smtp_had_error = 0;
1209 /* Set up the message size limit; this may be host-specific */
1211 thismessage_size_limit = expand_string_integer(message_size_limit, TRUE);
1212 if (expand_string_message != NULL)
1214 if (thismessage_size_limit == -1)
1215 log_write(0, LOG_MAIN|LOG_PANIC, "unable to expand message_size_limit: "
1216 "%s", expand_string_message);
1218 log_write(0, LOG_MAIN|LOG_PANIC, "invalid message_size_limit: "
1219 "%s", expand_string_message);
1220 smtp_closedown(US"Temporary local problem - please try later");
1224 /* When a message is input locally via the -bs or -bS options, sender_host_
1225 unknown is set unless -oMa was used to force an IP address, in which case it
1226 is checked like a real remote connection. When -bs is used from inetd, this
1227 flag is not set, causing the sending host to be checked. The code that deals
1228 with IP source routing (if configured) is never required for -bs or -bS and
1229 the flag sender_host_notsocket is used to suppress it.
1231 If smtp_accept_max and smtp_accept_reserve are set, keep some connections in
1232 reserve for certain hosts and/or networks. */
1234 if (!sender_host_unknown)
1237 BOOL reserved_host = FALSE;
1239 /* Look up IP options (source routing info) on the socket if this is not an
1240 -oMa "host", and if any are found, log them and drop the connection.
1242 Linux (and others now, see below) is different to everyone else, so there
1243 has to be some conditional compilation here. Versions of Linux before 2.1.15
1244 used a structure whose name was "options". Somebody finally realized that
1245 this name was silly, and it got changed to "ip_options". I use the
1246 newer name here, but there is a fudge in the script that sets up os.h
1247 to define a macro in older Linux systems.
1249 Sigh. Linux is a fast-moving target. Another generation of Linux uses
1250 glibc 2, which has chosen ip_opts for the structure name. This is now
1251 really a glibc thing rather than a Linux thing, so the condition name
1252 has been changed to reflect this. It is relevant also to GNU/Hurd.
1254 Mac OS 10.x (Darwin) is like the later glibc versions, but without the
1255 setting of the __GLIBC__ macro, so we can't detect it automatically. There's
1256 a special macro defined in the os.h file.
1258 Some DGUX versions on older hardware appear not to support IP options at
1259 all, so there is now a general macro which can be set to cut out this
1262 How to do this properly in IPv6 is not yet known. */
1264 #if !HAVE_IPV6 && !defined(NO_IP_OPTIONS)
1266 #ifdef GLIBC_IP_OPTIONS
1267 #if (!defined __GLIBC__) || (__GLIBC__ < 2)
1272 #elif defined DARWIN_IP_OPTIONS
1278 if (!host_checking && !sender_host_notsocket)
1281 EXIM_SOCKLEN_T optlen = sizeof(struct ip_options) + MAX_IPOPTLEN;
1282 struct ip_options *ipopt = store_get(optlen);
1284 struct ip_opts ipoptblock;
1285 struct ip_opts *ipopt = &ipoptblock;
1286 EXIM_SOCKLEN_T optlen = sizeof(ipoptblock);
1288 struct ipoption ipoptblock;
1289 struct ipoption *ipopt = &ipoptblock;
1290 EXIM_SOCKLEN_T optlen = sizeof(ipoptblock);
1293 /* Occasional genuine failures of getsockopt() have been seen - for
1294 example, "reset by peer". Therefore, just log and give up on this
1295 call, unless the error is ENOPROTOOPT. This error is given by systems
1296 that have the interfaces but not the mechanism - e.g. GNU/Hurd at the time
1297 of writing. So for that error, carry on - we just can't do an IP options
1300 DEBUG(D_receive) debug_printf("checking for IP options\n");
1302 if (getsockopt(fileno(smtp_out), IPPROTO_IP, IP_OPTIONS, (uschar *)(ipopt),
1305 if (errno != ENOPROTOOPT)
1307 log_write(0, LOG_MAIN, "getsockopt() failed from %s: %s",
1308 host_and_ident(FALSE), strerror(errno));
1309 smtp_printf("451 SMTP service not available\r\n");
1314 /* Deal with any IP options that are set. On the systems I have looked at,
1315 the value of MAX_IPOPTLEN has been 40, meaning that there should never be
1316 more logging data than will fit in big_buffer. Nevertheless, after somebody
1317 questioned this code, I've added in some paranoid checking. */
1319 else if (optlen > 0)
1321 uschar *p = big_buffer;
1322 uschar *pend = big_buffer + big_buffer_size;
1323 uschar *opt, *adptr;
1325 struct in_addr addr;
1328 uschar *optstart = (uschar *)(ipopt->__data);
1330 uschar *optstart = (uschar *)(ipopt->ip_opts);
1332 uschar *optstart = (uschar *)(ipopt->ipopt_list);
1335 DEBUG(D_receive) debug_printf("IP options exist\n");
1337 Ustrcpy(p, "IP options on incoming call:");
1340 for (opt = optstart; opt != NULL &&
1341 opt < (uschar *)(ipopt) + optlen;)
1355 if (!string_format(p, pend-p, " %s [@%s",
1356 (*opt == IPOPT_SSRR)? "SSRR" : "LSRR",
1358 inet_ntoa(*((struct in_addr *)(&(ipopt->faddr))))))
1360 inet_ntoa(ipopt->ip_dst)))
1362 inet_ntoa(ipopt->ipopt_dst)))
1370 optcount = (opt[1] - 3) / sizeof(struct in_addr);
1372 while (optcount-- > 0)
1374 memcpy(&addr, adptr, sizeof(addr));
1375 if (!string_format(p, pend - p - 1, "%s%s",
1376 (optcount == 0)? ":" : "@", inet_ntoa(addr)))
1382 adptr += sizeof(struct in_addr);
1391 if (pend - p < 4 + 3*opt[1]) { opt = NULL; break; }
1394 for (i = 0; i < opt[1]; i++)
1396 sprintf(CS p, "%2.2x ", opt[i]);
1407 log_write(0, LOG_MAIN, "%s", big_buffer);
1409 /* Refuse any call with IP options. This is what tcpwrappers 7.5 does. */
1411 log_write(0, LOG_MAIN|LOG_REJECT,
1412 "connection from %s refused (IP options)", host_and_ident(FALSE));
1414 smtp_printf("554 SMTP service not available\r\n");
1418 /* Length of options = 0 => there are no options */
1420 else DEBUG(D_receive) debug_printf("no IP options found\n");
1422 #endif /* HAVE_IPV6 && !defined(NO_IP_OPTIONS) */
1424 /* Set keep-alive in socket options. The option is on by default. This
1425 setting is an attempt to get rid of some hanging connections that stick in
1426 read() when the remote end (usually a dialup) goes away. */
1428 if (smtp_accept_keepalive && !sender_host_notsocket)
1429 ip_keepalive(fileno(smtp_out), sender_host_address, FALSE);
1431 /* If the current host matches host_lookup, set the name by doing a
1432 reverse lookup. On failure, sender_host_name will be NULL and
1433 host_lookup_failed will be TRUE. This may or may not be serious - optional
1436 if (verify_check_host(&host_lookup) == OK)
1438 (void)host_name_lookup();
1439 host_build_sender_fullhost();
1442 /* Delay this until we have the full name, if it is looked up. */
1444 set_process_info("handling incoming connection from %s",
1445 host_and_ident(FALSE));
1447 /* Start up TLS if tls_on_connect is set. This is for supporting the legacy
1448 smtps port for use with older style SSL MTAs. */
1451 if (tls_on_connect && tls_server_start(tls_require_ciphers) != OK)
1455 /* Test for explicit connection rejection */
1457 if (verify_check_host(&host_reject_connection) == OK)
1459 log_write(L_connection_reject, LOG_MAIN|LOG_REJECT, "refused connection "
1460 "from %s (host_reject_connection)", host_and_ident(FALSE));
1461 smtp_printf("554 SMTP service not available\r\n");
1465 /* Test with TCP Wrappers if so configured. There is a problem in that
1466 hosts_ctl() returns 0 (deny) under a number of system failure circumstances,
1467 such as disks dying. In these cases, it is desirable to reject with a 4xx
1468 error instead of a 5xx error. There isn't a "right" way to detect such
1469 problems. The following kludge is used: errno is zeroed before calling
1470 hosts_ctl(). If the result is "reject", a 5xx error is given only if the
1471 value of errno is 0 or ENOENT (which happens if /etc/hosts.{allow,deny} does
1474 #ifdef USE_TCP_WRAPPERS
1476 if (!hosts_ctl("exim",
1477 (sender_host_name == NULL)? STRING_UNKNOWN : CS sender_host_name,
1478 (sender_host_address == NULL)? STRING_UNKNOWN : CS sender_host_address,
1479 (sender_ident == NULL)? STRING_UNKNOWN : CS sender_ident))
1481 if (errno == 0 || errno == ENOENT)
1483 HDEBUG(D_receive) debug_printf("tcp wrappers rejection\n");
1484 log_write(L_connection_reject,
1485 LOG_MAIN|LOG_REJECT, "refused connection from %s "
1486 "(tcp wrappers)", host_and_ident(FALSE));
1487 smtp_printf("554 SMTP service not available\r\n");
1491 int save_errno = errno;
1492 HDEBUG(D_receive) debug_printf("tcp wrappers rejected with unexpected "
1493 "errno value %d\n", save_errno);
1494 log_write(L_connection_reject,
1495 LOG_MAIN|LOG_REJECT, "temporarily refused connection from %s "
1496 "(tcp wrappers errno=%d)", host_and_ident(FALSE), save_errno);
1497 smtp_printf("451 Temporary local problem - please try later\r\n");
1503 /* Check for reserved slots. Note that the count value doesn't include
1504 this process, as it gets upped in the parent process. */
1506 if (smtp_accept_max > 0 &&
1507 smtp_accept_count + 1 > smtp_accept_max - smtp_accept_reserve)
1509 if ((rc = verify_check_host(&smtp_reserve_hosts)) != OK)
1511 log_write(L_connection_reject,
1512 LOG_MAIN, "temporarily refused connection from %s: not in "
1513 "reserve list: connected=%d max=%d reserve=%d%s",
1514 host_and_ident(FALSE), smtp_accept_count, smtp_accept_max,
1515 smtp_accept_reserve, (rc == DEFER)? " (lookup deferred)" : "");
1516 smtp_printf("421 %s: Too many concurrent SMTP connections; "
1517 "please try again later\r\n", smtp_active_hostname);
1520 reserved_host = TRUE;
1523 /* If a load level above which only messages from reserved hosts are
1524 accepted is set, check the load. For incoming calls via the daemon, the
1525 check is done in the superior process if there are no reserved hosts, to
1526 save a fork. In all cases, the load average will already be available
1527 in a global variable at this point. */
1529 if (smtp_load_reserve >= 0 &&
1530 load_average > smtp_load_reserve &&
1532 verify_check_host(&smtp_reserve_hosts) != OK)
1534 log_write(L_connection_reject,
1535 LOG_MAIN, "temporarily refused connection from %s: not in "
1536 "reserve list and load average = %.2f", host_and_ident(FALSE),
1537 (double)load_average/1000.0);
1538 smtp_printf("421 %s: Too much load; please try again later\r\n",
1539 smtp_active_hostname);
1543 /* Determine whether unqualified senders or recipients are permitted
1544 for this host. Unfortunately, we have to do this every time, in order to
1545 set the flags so that they can be inspected when considering qualifying
1546 addresses in the headers. For a site that permits no qualification, this
1547 won't take long, however. */
1549 allow_unqualified_sender =
1550 verify_check_host(&sender_unqualified_hosts) == OK;
1552 allow_unqualified_recipient =
1553 verify_check_host(&recipient_unqualified_hosts) == OK;
1555 /* Determine whether HELO/EHLO is required for this host. The requirement
1556 can be hard or soft. */
1558 helo_required = verify_check_host(&helo_verify_hosts) == OK;
1560 helo_verify = verify_check_host(&helo_try_verify_hosts) == OK;
1562 /* Determine whether this hosts is permitted to send syntactic junk
1563 after a HELO or EHLO command. */
1565 helo_accept_junk = verify_check_host(&helo_accept_junk_hosts) == OK;
1568 /* For batch SMTP input we are now done. */
1570 if (smtp_batched_input) return TRUE;
1572 /* Run the ACL if it exists */
1574 if (acl_smtp_connect != NULL)
1577 uschar *user_msg, *log_msg;
1578 rc = acl_check(ACL_WHERE_CONNECT, NULL, acl_smtp_connect, &user_msg,
1582 (void)smtp_handle_acl_fail(ACL_WHERE_CONNECT, rc, user_msg, log_msg);
1587 /* Output the initial message for a two-way SMTP connection. It may contain
1588 newlines, which then cause a multi-line response to be given. */
1590 s = expand_string(smtp_banner);
1592 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "Expansion of \"%s\" (smtp_banner) "
1593 "failed: %s", smtp_banner, expand_string_message);
1595 /* Remove any terminating newlines; might as well remove trailing space too */
1598 while (p > s && isspace(p[-1])) p--;
1601 /* It seems that CC:Mail is braindead, and assumes that the greeting message
1602 is all contained in a single IP packet. The original code wrote out the
1603 greeting using several calls to fprint/fputc, and on busy servers this could
1604 cause it to be split over more than one packet - which caused CC:Mail to fall
1605 over when it got the second part of the greeting after sending its first
1606 command. Sigh. To try to avoid this, build the complete greeting message
1607 first, and output it in one fell swoop. This gives a better chance of it
1608 ending up as a single packet. */
1610 ss = store_get(size);
1614 do /* At least once, in case we have an empty string */
1617 uschar *linebreak = Ustrchr(p, '\n');
1618 if (linebreak == NULL)
1621 ss = string_cat(ss, &size, &ptr, US"220 ", 4);
1625 len = linebreak - p;
1626 ss = string_cat(ss, &size, &ptr, US"220-", 4);
1628 ss = string_cat(ss, &size, &ptr, p, len);
1629 ss = string_cat(ss, &size, &ptr, US"\r\n", 2);
1631 if (linebreak != NULL) p++;
1635 ss[ptr] = 0; /* string_cat leaves room for this */
1637 /* Before we write the banner, check that there is no input pending, unless
1638 this synchronisation check is disabled. */
1640 if (smtp_enforce_sync && sender_host_address != NULL && !sender_host_notsocket)
1643 struct timeval tzero;
1647 FD_SET(fileno(smtp_in), &fds);
1648 if (select(fileno(smtp_in) + 1, (SELECT_ARG2_TYPE *)&fds, NULL, NULL,
1651 int rc = read(fileno(smtp_in), smtp_inbuffer, in_buffer_size);
1654 if (rc > 150) rc = 150;
1655 smtp_inbuffer[rc] = 0;
1656 log_write(0, LOG_MAIN|LOG_REJECT, "SMTP protocol "
1657 "synchronization error (input sent without waiting for greeting): "
1658 "rejected connection from %s input=\"%s\"", host_and_ident(TRUE),
1659 string_printing(smtp_inbuffer));
1660 smtp_printf("554 SMTP synchronization error\r\n");
1666 /* Now output the banner */
1668 smtp_printf("%s", ss);
1676 /*************************************************
1677 * Handle SMTP syntax and protocol errors *
1678 *************************************************/
1680 /* Write to the log for SMTP syntax errors in incoming commands, if configured
1681 to do so. Then transmit the error response. The return value depends on the
1682 number of syntax and protocol errors in this SMTP session.
1685 type error type, given as a log flag bit
1686 code response code; <= 0 means don't send a response
1687 data data to reflect in the response (can be NULL)
1688 errmess the error message
1690 Returns: -1 limit of syntax/protocol errors NOT exceeded
1691 +1 limit of syntax/protocol errors IS exceeded
1693 These values fit in with the values of the "done" variable in the main
1694 processing loop in smtp_setup_msg(). */
1697 synprot_error(int type, int code, uschar *data, uschar *errmess)
1701 log_write(type, LOG_MAIN, "SMTP %s error in \"%s\" %s %s",
1702 (type == L_smtp_syntax_error)? "syntax" : "protocol",
1703 string_printing(smtp_cmd_buffer), host_and_ident(TRUE), errmess);
1705 if (++synprot_error_count > smtp_max_synprot_errors)
1708 log_write(0, LOG_MAIN|LOG_REJECT, "SMTP call from %s dropped: too many "
1709 "syntax or protocol errors (last command was \"%s\")",
1710 host_and_ident(FALSE), smtp_cmd_buffer);
1715 smtp_printf("%d%c%s%s%s\r\n", code, (yield == 1)? '-' : ' ',
1716 (data == NULL)? US"" : data, (data == NULL)? US"" : US": ", errmess);
1718 smtp_printf("%d Too many syntax or protocol errors\r\n", code);
1727 /*************************************************
1728 * Log incomplete transactions *
1729 *************************************************/
1731 /* This function is called after a transaction has been aborted by RSET, QUIT,
1732 connection drops or other errors. It logs the envelope information received
1733 so far in order to preserve address verification attempts.
1735 Argument: string to indicate what aborted the transaction
1740 incomplete_transaction_log(uschar *what)
1742 if (sender_address == NULL || /* No transaction in progress */
1743 (log_write_selector & L_smtp_incomplete_transaction) == 0 /* Not logging */
1746 /* Build list of recipients for logging */
1748 if (recipients_count > 0)
1751 raw_recipients = store_get(recipients_count * sizeof(uschar *));
1752 for (i = 0; i < recipients_count; i++)
1753 raw_recipients[i] = recipients_list[i].address;
1754 raw_recipients_count = recipients_count;
1757 log_write(L_smtp_incomplete_transaction, LOG_MAIN|LOG_SENDER|LOG_RECIPIENTS,
1758 "%s incomplete transaction (%s)", host_and_ident(TRUE), what);
1764 /*************************************************
1765 * Send SMTP response, possibly multiline *
1766 *************************************************/
1768 /* There are, it seems, broken clients out there that cannot handle multiline
1769 responses. If no_multiline_responses is TRUE (it can be set from an ACL), we
1770 output nothing for non-final calls, and only the first line for anything else.
1773 code SMTP code, may involve extended status codes
1774 codelen length of smtp code; uf > 3 there's an ESC
1775 final FALSE if the last line isn't the final line
1776 msg message text, possibly containing newlines
1782 smtp_respond(uschar* code, int codelen, BOOL final, uschar *msg)
1787 if (!final && no_multiline_responses) return;
1792 esclen = codelen - 4;
1797 uschar *nl = Ustrchr(msg, '\n');
1800 smtp_printf("%.3s%c%.*s%s\r\n", code, final? ' ':'-', esclen, esc, msg);
1803 else if (nl[1] == 0 || no_multiline_responses)
1805 smtp_printf("%.3s%c%.*s%.*s\r\n", code, final? ' ':'-', esclen, esc,
1806 (int)(nl - msg), msg);
1811 smtp_printf("%.3s-%.*s%.*s\r\n", code, esclen, esc, (int)(nl - msg), msg);
1813 while (isspace(*msg)) msg++;
1821 /*************************************************
1822 * Handle an ACL failure *
1823 *************************************************/
1825 /* This function is called when acl_check() fails. As well as calls from within
1826 this module, it is called from receive.c for an ACL after DATA. It sorts out
1827 logging the incident, and sets up the error response. A message containing
1828 newlines is turned into a multiline SMTP response, but for logging, only the
1831 There's a table of default permanent failure response codes to use in
1832 globals.c, along with the table of names. VFRY is special. Despite RFC1123 it
1833 defaults disabled in Exim. However, discussion in connection with RFC 821bis
1834 (aka RFC 2821) has concluded that the response should be 252 in the disabled
1835 state, because there are broken clients that try VRFY before RCPT. A 5xx
1836 response should be given only when the address is positively known to be
1837 undeliverable. Sigh. Also, for ETRN, 458 is given on refusal, and for AUTH,
1840 From Exim 4.63, it is possible to override the response code details by
1841 providing a suitable response code string at the start of the message provided
1842 in user_msg. The code's first digit is checked for validity.
1845 where where the ACL was called from
1847 user_msg a message that can be included in an SMTP response
1848 log_msg a message for logging
1850 Returns: 0 in most cases
1851 2 if the failure code was FAIL_DROP, in which case the
1852 SMTP connection should be dropped (this value fits with the
1853 "done" variable in smtp_setup_msg() below)
1857 smtp_handle_acl_fail(int where, int rc, uschar *user_msg, uschar *log_msg)
1859 BOOL drop = rc == FAIL_DROP;
1864 uschar *sender_info = US"";
1866 #ifdef WITH_CONTENT_SCAN
1867 (where == ACL_WHERE_MIME)? US"during MIME ACL checks" :
1869 (where == ACL_WHERE_PREDATA)? US"DATA" :
1870 (where == ACL_WHERE_DATA)? US"after DATA" :
1871 (smtp_cmd_argument == NULL)?
1872 string_sprintf("%s in \"connect\" ACL", acl_wherenames[where]) :
1873 string_sprintf("%s %s", acl_wherenames[where], smtp_cmd_argument);
1875 if (drop) rc = FAIL;
1877 /* Set the default SMTP code */
1879 smtp_code = (rc != FAIL)? US"451" : acl_wherecodes[where];
1881 /* Check a user message for starting with a response code and optionally an
1882 extended status code. If found, check that the first digit is valid, and if so,
1883 use it instead of the default code. */
1885 if (user_msg != NULL)
1887 int n = pcre_exec(regex_smtp_code, NULL, CS user_msg, Ustrlen(user_msg), 0,
1888 PCRE_EOPT, ovector, sizeof(ovector)/sizeof(int));
1891 if (user_msg[0] != smtp_code[0])
1893 log_write(0, LOG_MAIN|LOG_PANIC, "configured error code starts with "
1894 "incorrect digit (expected %c) in \"%s\"", smtp_code[0], user_msg);
1896 /* If log_msg == user_msg (the default set in acl.c if no log message is
1897 specified, we must adjust the log message to show the code that is
1898 actually going to be used. */
1900 if (log_msg == user_msg)
1901 log_msg = string_sprintf("%s %s", smtp_code, log_msg + ovector[1]);
1905 smtp_code = user_msg;
1906 codelen = ovector[1]; /* Includes final space */
1908 user_msg += ovector[1]; /* Chop the code off the message */
1912 /* We used to have sender_address here; however, there was a bug that was not
1913 updating sender_address after a rewrite during a verify. When this bug was
1914 fixed, sender_address at this point became the rewritten address. I'm not sure
1915 this is what should be logged, so I've changed to logging the unrewritten
1916 address to retain backward compatibility. */
1918 #ifndef WITH_CONTENT_SCAN
1919 if (where == ACL_WHERE_RCPT || where == ACL_WHERE_DATA)
1921 if (where == ACL_WHERE_RCPT || where == ACL_WHERE_DATA || where == ACL_WHERE_MIME)
1924 sender_info = string_sprintf("F=<%s> ", (sender_address_unrewritten != NULL)?
1925 sender_address_unrewritten : sender_address);
1928 /* If there's been a sender verification failure with a specific message, and
1929 we have not sent a response about it yet, do so now, as a preliminary line for
1930 failures, but not defers. However, always log it for defer, and log it for fail
1931 unless the sender_verify_fail log selector has been turned off. */
1933 if (sender_verified_failed != NULL &&
1934 !testflag(sender_verified_failed, af_sverify_told))
1936 setflag(sender_verified_failed, af_sverify_told);
1938 if (rc != FAIL || (log_extra_selector & LX_sender_verify_fail) != 0)
1939 log_write(0, LOG_MAIN|LOG_REJECT, "%s sender verify %s for <%s>%s",
1940 host_and_ident(TRUE),
1941 ((sender_verified_failed->special_action & 255) == DEFER)? "defer":"fail",
1942 sender_verified_failed->address,
1943 (sender_verified_failed->message == NULL)? US"" :
1944 string_sprintf(": %s", sender_verified_failed->message));
1946 if (rc == FAIL && sender_verified_failed->user_message != NULL)
1947 smtp_respond(smtp_code, codelen, FALSE, string_sprintf(
1948 testflag(sender_verified_failed, af_verify_pmfail)?
1949 "Postmaster verification failed while checking <%s>\n%s\n"
1950 "Several RFCs state that you are required to have a postmaster\n"
1951 "mailbox for each mail domain. This host does not accept mail\n"
1952 "from domains whose servers reject the postmaster address."
1954 testflag(sender_verified_failed, af_verify_nsfail)?
1955 "Callback setup failed while verifying <%s>\n%s\n"
1956 "The initial connection, or a HELO or MAIL FROM:<> command was\n"
1957 "rejected. Refusing MAIL FROM:<> does not help fight spam, disregards\n"
1958 "RFC requirements, and stops you from receiving standard bounce\n"
1959 "messages. This host does not accept mail from domains whose servers\n"
1962 "Verification failed for <%s>\n%s",
1963 sender_verified_failed->address,
1964 sender_verified_failed->user_message));
1967 /* Sort out text for logging */
1969 log_msg = (log_msg == NULL)? US"" : string_sprintf(": %s", log_msg);
1970 lognl = Ustrchr(log_msg, '\n');
1971 if (lognl != NULL) *lognl = 0;
1973 /* Send permanent failure response to the command, but the code used isn't
1974 always a 5xx one - see comments at the start of this function. If the original
1975 rc was FAIL_DROP we drop the connection and yield 2. */
1977 if (rc == FAIL) smtp_respond(smtp_code, codelen, TRUE, (user_msg == NULL)?
1978 US"Administrative prohibition" : user_msg);
1980 /* Send temporary failure response to the command. Don't give any details,
1981 unless acl_temp_details is set. This is TRUE for a callout defer, a "defer"
1982 verb, and for a header verify when smtp_return_error_details is set.
1984 This conditional logic is all somewhat of a mess because of the odd
1985 interactions between temp_details and return_error_details. One day it should
1986 be re-implemented in a tidier fashion. */
1990 if (acl_temp_details && user_msg != NULL)
1992 if (smtp_return_error_details &&
1993 sender_verified_failed != NULL &&
1994 sender_verified_failed->message != NULL)
1996 smtp_respond(smtp_code, codelen, FALSE, sender_verified_failed->message);
1998 smtp_respond(smtp_code, codelen, TRUE, user_msg);
2001 smtp_respond(smtp_code, codelen, TRUE,
2002 US"Temporary local problem - please try later");
2005 /* Log the incident to the logs that are specified by log_reject_target
2006 (default main, reject). This can be empty to suppress logging of rejections. If
2007 the connection is not forcibly to be dropped, return 0. Otherwise, log why it
2008 is closing if required and return 2. */
2010 if (log_reject_target != 0)
2011 log_write(0, log_reject_target, "%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 /* Deal with the case of -bs without an IP address */
2059 else if (sender_host_address == NULL)
2061 HDEBUG(D_receive) debug_printf("no client IP address: assume success\n");
2062 helo_verified = TRUE;
2065 /* Deal with the more common case when there is a sending IP address */
2067 else if (sender_helo_name[0] == '[')
2069 helo_verified = Ustrncmp(sender_helo_name+1, sender_host_address,
2070 Ustrlen(sender_host_address)) == 0;
2075 if (strncmpic(sender_host_address, US"::ffff:", 7) == 0)
2076 helo_verified = Ustrncmp(sender_helo_name + 1,
2077 sender_host_address + 7, Ustrlen(sender_host_address) - 7) == 0;
2082 { if (helo_verified) debug_printf("matched host address\n"); }
2085 /* Do a reverse lookup if one hasn't already given a positive or negative
2086 response. If that fails, or the name doesn't match, try checking with a forward
2091 if (sender_host_name == NULL && !host_lookup_failed)
2092 yield = host_name_lookup() != DEFER;
2094 /* If a host name is known, check it and all its aliases. */
2096 if (sender_host_name != NULL)
2098 helo_verified = strcmpic(sender_host_name, sender_helo_name) == 0;
2102 HDEBUG(D_receive) debug_printf("matched host name\n");
2106 uschar **aliases = sender_host_aliases;
2107 while (*aliases != NULL)
2109 helo_verified = strcmpic(*aliases++, sender_helo_name) == 0;
2110 if (helo_verified) break;
2115 debug_printf("matched alias %s\n", *(--aliases));
2120 /* Final attempt: try a forward lookup of the helo name */
2126 h.name = sender_helo_name;
2130 HDEBUG(D_receive) debug_printf("getting IP address for %s\n",
2132 rc = host_find_byname(&h, NULL, 0, NULL, TRUE);
2133 if (rc == HOST_FOUND || rc == HOST_FOUND_LOCAL)
2138 if (Ustrcmp(hh->address, sender_host_address) == 0)
2140 helo_verified = TRUE;
2142 debug_printf("IP address for %s matches calling address\n",
2152 if (!helo_verified) helo_verify_failed = TRUE; /* We've tried ... */
2159 /*************************************************
2160 * Initialize for SMTP incoming message *
2161 *************************************************/
2163 /* This function conducts the initial dialogue at the start of an incoming SMTP
2164 message, and builds a list of recipients. However, if the incoming message
2165 is part of a batch (-bS option) a separate function is called since it would
2166 be messy having tests splattered about all over this function. This function
2167 therefore handles the case where interaction is occurring. The input and output
2168 files are set up in smtp_in and smtp_out.
2170 The global recipients_list is set to point to a vector of recipient_item
2171 blocks, whose number is given by recipients_count. This is extended by the
2172 receive_add_recipient() function. The global variable sender_address is set to
2173 the sender's address. The yield is +1 if a message has been successfully
2174 started, 0 if a QUIT command was encountered or the connection was refused from
2175 the particular host, or -1 if the connection was lost.
2179 Returns: > 0 message successfully started (reached DATA)
2180 = 0 QUIT read or end of file reached or call refused
2185 smtp_setup_msg(void)
2188 BOOL toomany = FALSE;
2189 BOOL discarded = FALSE;
2190 BOOL last_was_rej_mail = FALSE;
2191 BOOL last_was_rcpt = FALSE;
2192 void *reset_point = store_get(0);
2194 DEBUG(D_receive) debug_printf("smtp_setup_msg entered\n");
2196 /* Reset for start of new message. We allow one RSET not to be counted as a
2197 nonmail command, for those MTAs that insist on sending it between every
2198 message. Ditto for EHLO/HELO and for STARTTLS, to allow for going in and out of
2199 TLS between messages (an Exim client may do this if it has messages queued up
2200 for the host). Note: we do NOT reset AUTH at this point. */
2202 smtp_reset(reset_point);
2203 message_ended = END_NOTSTARTED;
2205 cmd_list[CMD_LIST_RSET].is_mail_cmd = TRUE;
2206 cmd_list[CMD_LIST_HELO].is_mail_cmd = TRUE;
2207 cmd_list[CMD_LIST_EHLO].is_mail_cmd = TRUE;
2209 cmd_list[CMD_LIST_STARTTLS].is_mail_cmd = TRUE;
2212 /* Set the local signal handler for SIGTERM - it tries to end off tidily */
2214 os_non_restarting_signal(SIGTERM, command_sigterm_handler);
2216 /* Batched SMTP is handled in a different function. */
2218 if (smtp_batched_input) return smtp_setup_batch_msg();
2220 /* Deal with SMTP commands. This loop is exited by setting done to a POSITIVE
2221 value. The values are 2 larger than the required yield of the function. */
2226 uschar *etrn_command;
2227 uschar *etrn_serialize_key;
2229 uschar *user_msg, *log_msg;
2230 uschar *recipient = NULL;
2231 uschar *hello = NULL;
2232 uschar *set_id = NULL;
2234 BOOL was_rej_mail = FALSE;
2235 BOOL was_rcpt = FALSE;
2236 void (*oldsignal)(int);
2238 int start, end, sender_domain, recipient_domain;
2243 switch(smtp_read_command(TRUE))
2245 /* The AUTH command is not permitted to occur inside a transaction, and may
2246 occur successfully only once per connection. Actually, that isn't quite
2247 true. When TLS is started, all previous information about a connection must
2248 be discarded, so a new AUTH is permitted at that time.
2250 AUTH may only be used when it has been advertised. However, it seems that
2251 there are clients that send AUTH when it hasn't been advertised, some of
2252 them even doing this after HELO. And there are MTAs that accept this. Sigh.
2253 So there's a get-out that allows this to happen.
2255 AUTH is initially labelled as a "nonmail command" so that one occurrence
2256 doesn't get counted. We change the label here so that multiple failing
2257 AUTHS will eventually hit the nonmail threshold. */
2260 authentication_failed = TRUE;
2261 cmd_list[CMD_LIST_AUTH].is_mail_cmd = FALSE;
2263 if (!auth_advertised && !allow_auth_unadvertised)
2265 done = synprot_error(L_smtp_protocol_error, 503, NULL,
2266 US"AUTH command used when not advertised");
2269 if (sender_host_authenticated != NULL)
2271 done = synprot_error(L_smtp_protocol_error, 503, NULL,
2272 US"already authenticated");
2275 if (sender_address != NULL)
2277 done = synprot_error(L_smtp_protocol_error, 503, NULL,
2278 US"not permitted in mail transaction");
2284 if (acl_smtp_auth != NULL)
2286 rc = acl_check(ACL_WHERE_AUTH, NULL, acl_smtp_auth, &user_msg, &log_msg);
2289 done = smtp_handle_acl_fail(ACL_WHERE_AUTH, rc, user_msg, log_msg);
2294 /* Find the name of the requested authentication mechanism. */
2296 s = smtp_cmd_argument;
2297 while ((c = *smtp_cmd_argument) != 0 && !isspace(c))
2299 if (!isalnum(c) && c != '-' && c != '_')
2301 done = synprot_error(L_smtp_syntax_error, 501, NULL,
2302 US"invalid character in authentication mechanism name");
2305 smtp_cmd_argument++;
2308 /* If not at the end of the line, we must be at white space. Terminate the
2309 name and move the pointer on to any data that may be present. */
2311 if (*smtp_cmd_argument != 0)
2313 *smtp_cmd_argument++ = 0;
2314 while (isspace(*smtp_cmd_argument)) smtp_cmd_argument++;
2317 /* Search for an authentication mechanism which is configured for use
2318 as a server and which has been advertised (unless, sigh, allow_auth_
2319 unadvertised is set). */
2321 for (au = auths; au != NULL; au = au->next)
2323 if (strcmpic(s, au->public_name) == 0 && au->server &&
2324 (au->advertised || allow_auth_unadvertised)) break;
2329 done = synprot_error(L_smtp_protocol_error, 504, NULL,
2330 string_sprintf("%s authentication mechanism not supported", s));
2334 /* Run the checking code, passing the remainder of the command line as
2335 data. Initials the $auth<n> variables as empty. Initialize $0 empty and set
2336 it as the only set numerical variable. The authenticator may set $auth<n>
2337 and also set other numeric variables. The $auth<n> variables are preferred
2338 nowadays; the numerical variables remain for backwards compatibility.
2340 Afterwards, have a go at expanding the set_id string, even if
2341 authentication failed - for bad passwords it can be useful to log the
2342 userid. On success, require set_id to expand and exist, and put it in
2343 authenticated_id. Save this in permanent store, as the working store gets
2344 reset at HELO, RSET, etc. */
2346 for (i = 0; i < AUTH_VARS; i++) auth_vars[i] = NULL;
2348 expand_nlength[0] = 0; /* $0 contains nothing */
2350 c = (au->info->servercode)(au, smtp_cmd_argument);
2351 if (au->set_id != NULL) set_id = expand_string(au->set_id);
2352 expand_nmax = -1; /* Reset numeric variables */
2353 for (i = 0; i < AUTH_VARS; i++) auth_vars[i] = NULL; /* Reset $auth<n> */
2355 /* The value of authenticated_id is stored in the spool file and printed in
2356 log lines. It must not contain binary zeros or newline characters. In
2357 normal use, it never will, but when playing around or testing, this error
2358 can (did) happen. To guard against this, ensure that the id contains only
2359 printing characters. */
2361 if (set_id != NULL) set_id = string_printing(set_id);
2363 /* For the non-OK cases, set up additional logging data if set_id
2368 if (set_id != NULL && *set_id != 0)
2369 set_id = string_sprintf(" (set_id=%s)", set_id);
2373 /* Switch on the result */
2378 if (au->set_id == NULL || set_id != NULL) /* Complete success */
2380 if (set_id != NULL) authenticated_id = string_copy_malloc(set_id);
2381 sender_host_authenticated = au->name;
2382 authentication_failed = FALSE;
2384 protocols[pextend + pauthed + ((tls_active >= 0)? pcrpted:0)] +
2385 ((sender_host_address != NULL)? pnlocal : 0);
2386 s = ss = US"235 Authentication succeeded";
2387 authenticated_by = au;
2391 /* Authentication succeeded, but we failed to expand the set_id string.
2392 Treat this as a temporary error. */
2394 auth_defer_msg = expand_string_message;
2398 s = string_sprintf("435 Unable to authenticate at present%s",
2399 auth_defer_user_msg);
2400 ss = string_sprintf("435 Unable to authenticate at present%s: %s",
2401 set_id, auth_defer_msg);
2405 s = ss = US"501 Invalid base64 data";
2409 s = ss = US"501 Authentication cancelled";
2413 s = ss = US"553 Initial data not expected";
2417 s = US"535 Incorrect authentication data";
2418 ss = string_sprintf("535 Incorrect authentication data%s", set_id);
2422 s = US"435 Internal error";
2423 ss = string_sprintf("435 Internal error%s: return %d from authentication "
2424 "check", set_id, c);
2428 smtp_printf("%s\r\n", s);
2430 log_write(0, LOG_MAIN|LOG_REJECT, "%s authenticator failed for %s: %s",
2431 au->name, host_and_ident(FALSE), ss);
2433 break; /* AUTH_CMD */
2435 /* The HELO/EHLO commands are permitted to appear in the middle of a
2436 session as well as at the beginning. They have the effect of a reset in
2437 addition to their other functions. Their absence at the start cannot be
2438 taken to be an error.
2442 If the EHLO command is not acceptable to the SMTP server, 501, 500,
2443 or 502 failure replies MUST be returned as appropriate. The SMTP
2444 server MUST stay in the same state after transmitting these replies
2445 that it was in before the EHLO was received.
2447 Therefore, we do not do the reset until after checking the command for
2448 acceptability. This change was made for Exim release 4.11. Previously
2449 it did the reset first. */
2460 HELO_EHLO: /* Common code for HELO and EHLO */
2461 cmd_list[CMD_LIST_HELO].is_mail_cmd = FALSE;
2462 cmd_list[CMD_LIST_EHLO].is_mail_cmd = FALSE;
2464 /* Reject the HELO if its argument was invalid or non-existent. A
2465 successful check causes the argument to be saved in malloc store. */
2467 if (!check_helo(smtp_cmd_argument))
2469 smtp_printf("501 Syntactically invalid %s argument(s)\r\n", hello);
2471 log_write(0, LOG_MAIN|LOG_REJECT, "rejected %s from %s: syntactically "
2472 "invalid argument(s): %s", hello, host_and_ident(FALSE),
2473 (*smtp_cmd_argument == 0)? US"(no argument given)" :
2474 string_printing(smtp_cmd_argument));
2476 if (++synprot_error_count > smtp_max_synprot_errors)
2478 log_write(0, LOG_MAIN|LOG_REJECT, "SMTP call from %s dropped: too many "
2479 "syntax or protocol errors (last command was \"%s\")",
2480 host_and_ident(FALSE), smtp_cmd_buffer);
2487 /* If sender_host_unknown is true, we have got here via the -bs interface,
2488 not called from inetd. Otherwise, we are running an IP connection and the
2489 host address will be set. If the helo name is the primary name of this
2490 host and we haven't done a reverse lookup, force one now. If helo_required
2491 is set, ensure that the HELO name matches the actual host. If helo_verify
2492 is set, do the same check, but softly. */
2494 if (!sender_host_unknown)
2496 BOOL old_helo_verified = helo_verified;
2497 uschar *p = smtp_cmd_argument;
2499 while (*p != 0 && !isspace(*p)) { *p = tolower(*p); p++; }
2502 /* Force a reverse lookup if HELO quoted something in helo_lookup_domains
2503 because otherwise the log can be confusing. */
2505 if (sender_host_name == NULL &&
2506 (deliver_domain = sender_helo_name, /* set $domain */
2507 match_isinlist(sender_helo_name, &helo_lookup_domains, 0,
2508 &domainlist_anchor, NULL, MCL_DOMAIN, TRUE, NULL)) == OK)
2509 (void)host_name_lookup();
2511 /* Rebuild the fullhost info to include the HELO name (and the real name
2512 if it was looked up.) */
2514 host_build_sender_fullhost(); /* Rebuild */
2515 set_process_info("handling%s incoming connection from %s",
2516 (tls_active >= 0)? " TLS" : "", host_and_ident(FALSE));
2518 /* Verify if configured. This doesn't give much security, but it does
2519 make some people happy to be able to do it. If helo_required is set,
2520 (host matches helo_verify_hosts) failure forces rejection. If helo_verify
2521 is set (host matches helo_try_verify_hosts), it does not. This is perhaps
2522 now obsolescent, since the verification can now be requested selectively
2525 helo_verified = helo_verify_failed = FALSE;
2526 if (helo_required || helo_verify)
2528 BOOL tempfail = !smtp_verify_helo();
2533 smtp_printf("%d %s argument does not match calling host\r\n",
2534 tempfail? 451 : 550, hello);
2535 log_write(0, LOG_MAIN|LOG_REJECT, "%srejected \"%s %s\" from %s",
2536 tempfail? "temporarily " : "",
2537 hello, sender_helo_name, host_and_ident(FALSE));
2538 helo_verified = old_helo_verified;
2539 break; /* End of HELO/EHLO processing */
2541 HDEBUG(D_all) debug_printf("%s verification failed but host is in "
2542 "helo_try_verify_hosts\n", hello);
2547 #ifdef EXPERIMENTAL_SPF
2548 /* set up SPF context */
2549 spf_init(sender_helo_name, sender_host_address);
2552 /* Apply an ACL check if one is defined */
2554 if (acl_smtp_helo != NULL)
2556 rc = acl_check(ACL_WHERE_HELO, NULL, acl_smtp_helo, &user_msg, &log_msg);
2559 done = smtp_handle_acl_fail(ACL_WHERE_HELO, rc, user_msg, log_msg);
2560 sender_helo_name = NULL;
2561 host_build_sender_fullhost(); /* Rebuild */
2566 /* The EHLO/HELO command is acceptable. Reset the protocol and the state,
2567 abandoning any previous message. */
2569 received_protocol = (esmtp?
2571 ((sender_host_authenticated != NULL)? pauthed : 0) +
2572 ((tls_active >= 0)? pcrpted : 0)]
2574 protocols[pnormal + ((tls_active >= 0)? pcrpted : 0)])
2576 ((sender_host_address != NULL)? pnlocal : 0);
2578 smtp_reset(reset_point);
2581 /* Generate an OK reply, including the ident if present, and also
2582 the IP address if present. Reflecting back the ident is intended
2583 as a deterrent to mail forgers. For maximum efficiency, and also
2584 because some broken systems expect each response to be in a single
2585 packet, arrange that it is sent in one write(). */
2587 auth_advertised = FALSE;
2588 pipelining_advertised = FALSE;
2590 tls_advertised = FALSE;
2593 s = string_sprintf("250 %s Hello %s%s%s",
2594 smtp_active_hostname,
2595 (sender_ident == NULL)? US"" : sender_ident,
2596 (sender_ident == NULL)? US"" : US" at ",
2597 (sender_host_name == NULL)? sender_helo_name : sender_host_name);
2602 if (sender_host_address != NULL)
2604 s = string_cat(s, &size, &ptr, US" [", 2);
2605 s = string_cat(s, &size, &ptr, sender_host_address,
2606 Ustrlen(sender_host_address));
2607 s = string_cat(s, &size, &ptr, US"]", 1);
2610 s = string_cat(s, &size, &ptr, US"\r\n", 2);
2612 /* If we received EHLO, we must create a multiline response which includes
2613 the functions supported. */
2619 /* I'm not entirely happy with this, as an MTA is supposed to check
2620 that it has enough room to accept a message of maximum size before
2621 it sends this. However, there seems little point in not sending it.
2622 The actual size check happens later at MAIL FROM time. By postponing it
2623 till then, VRFY and EXPN can be used after EHLO when space is short. */
2625 if (thismessage_size_limit > 0)
2627 sprintf(CS big_buffer, "250-SIZE %d\r\n", thismessage_size_limit);
2628 s = string_cat(s, &size, &ptr, big_buffer, Ustrlen(big_buffer));
2632 s = string_cat(s, &size, &ptr, US"250-SIZE\r\n", 10);
2635 /* Exim does not do protocol conversion or data conversion. It is 8-bit
2636 clean; if it has an 8-bit character in its hand, it just sends it. It
2637 cannot therefore specify 8BITMIME and remain consistent with the RFCs.
2638 However, some users want this option simply in order to stop MUAs
2639 mangling messages that contain top-bit-set characters. It is therefore
2640 provided as an option. */
2642 if (accept_8bitmime)
2643 s = string_cat(s, &size, &ptr, US"250-8BITMIME\r\n", 14);
2645 /* Advertise ETRN if there's an ACL checking whether a host is
2646 permitted to issue it; a check is made when any host actually tries. */
2648 if (acl_smtp_etrn != NULL)
2650 s = string_cat(s, &size, &ptr, US"250-ETRN\r\n", 10);
2653 /* Advertise EXPN if there's an ACL checking whether a host is
2654 permitted to issue it; a check is made when any host actually tries. */
2656 if (acl_smtp_expn != NULL)
2658 s = string_cat(s, &size, &ptr, US"250-EXPN\r\n", 10);
2661 /* Exim is quite happy with pipelining, so let the other end know that
2662 it is safe to use it, unless advertising is disabled. */
2664 if (verify_check_host(&pipelining_advertise_hosts) == OK)
2666 s = string_cat(s, &size, &ptr, US"250-PIPELINING\r\n", 16);
2667 sync_cmd_limit = NON_SYNC_CMD_PIPELINING;
2668 pipelining_advertised = TRUE;
2671 /* If any server authentication mechanisms are configured, advertise
2672 them if the current host is in auth_advertise_hosts. The problem with
2673 advertising always is that some clients then require users to
2674 authenticate (and aren't configurable otherwise) even though it may not
2675 be necessary (e.g. if the host is in host_accept_relay).
2677 RFC 2222 states that SASL mechanism names contain only upper case
2678 letters, so output the names in upper case, though we actually recognize
2679 them in either case in the AUTH command. */
2683 if (verify_check_host(&auth_advertise_hosts) == OK)
2687 for (au = auths; au != NULL; au = au->next)
2689 if (au->server && (au->advertise_condition == NULL ||
2690 expand_check_condition(au->advertise_condition, au->name,
2691 US"authenticator")))
2696 s = string_cat(s, &size, &ptr, US"250-AUTH", 8);
2698 auth_advertised = TRUE;
2701 s = string_cat(s, &size, &ptr, US" ", 1);
2702 s = string_cat(s, &size, &ptr, au->public_name,
2703 Ustrlen(au->public_name));
2704 while (++saveptr < ptr) s[saveptr] = toupper(s[saveptr]);
2705 au->advertised = TRUE;
2707 else au->advertised = FALSE;
2709 if (!first) s = string_cat(s, &size, &ptr, US"\r\n", 2);
2713 /* Advertise TLS (Transport Level Security) aka SSL (Secure Socket Layer)
2714 if it has been included in the binary, and the host matches
2715 tls_advertise_hosts. We must *not* advertise if we are already in a
2716 secure connection. */
2719 if (tls_active < 0 &&
2720 verify_check_host(&tls_advertise_hosts) != FAIL)
2722 s = string_cat(s, &size, &ptr, US"250-STARTTLS\r\n", 14);
2723 tls_advertised = TRUE;
2727 /* Finish off the multiline reply with one that is always available. */
2729 s = string_cat(s, &size, &ptr, US"250 HELP\r\n", 10);
2732 /* Terminate the string (for debug), write it, and note that HELO/EHLO
2738 if (tls_active >= 0) (void)tls_write(s, ptr); else
2741 (void)fwrite(s, 1, ptr, smtp_out);
2745 while ((cr = Ustrchr(s, '\r')) != NULL) /* lose CRs */
2746 memmove(cr, cr + 1, (ptr--) - (cr - s));
2747 debug_printf("SMTP>> %s", s);
2750 break; /* HELO/EHLO */
2753 /* The MAIL command requires an address as an operand. All we do
2754 here is to parse it for syntactic correctness. The form "<>" is
2755 a special case which converts into an empty string. The start/end
2756 pointers in the original are not used further for this address, as
2757 it is the canonical extracted address which is all that is kept. */
2760 smtp_mailcmd_count++; /* Count for limit and ratelimit */
2761 was_rej_mail = TRUE; /* Reset if accepted */
2763 if (helo_required && !helo_seen)
2765 smtp_printf("503 HELO or EHLO required\r\n");
2766 log_write(0, LOG_MAIN|LOG_REJECT, "rejected MAIL from %s: no "
2767 "HELO/EHLO given", host_and_ident(FALSE));
2771 if (sender_address != NULL)
2773 done = synprot_error(L_smtp_protocol_error, 503, NULL,
2774 US"sender already given");
2778 if (smtp_cmd_argument[0] == 0)
2780 done = synprot_error(L_smtp_protocol_error, 501, NULL,
2781 US"MAIL must have an address operand");
2785 /* Check to see if the limit for messages per connection would be
2786 exceeded by accepting further messages. */
2788 if (smtp_accept_max_per_connection > 0 &&
2789 smtp_mailcmd_count > smtp_accept_max_per_connection)
2791 smtp_printf("421 too many messages in this connection\r\n");
2792 log_write(0, LOG_MAIN|LOG_REJECT, "rejected MAIL command %s: too many "
2793 "messages in one connection", host_and_ident(TRUE));
2797 /* Reset for start of message - even if this is going to fail, we
2798 obviously need to throw away any previous data. */
2800 smtp_reset(reset_point);
2802 sender_data = recipient_data = NULL;
2804 /* Loop, checking for ESMTP additions to the MAIL FROM command. */
2808 uschar *name, *value, *end;
2809 unsigned long int size;
2811 if (!extract_option(&name, &value)) break;
2813 /* Handle SIZE= by reading the value. We don't do the check till later,
2814 in order to be able to log the sender address on failure. */
2816 if (strcmpic(name, US"SIZE") == 0 &&
2817 ((size = (int)Ustrtoul(value, &end, 10)), *end == 0))
2819 if ((size == ULONG_MAX && errno == ERANGE) || size > INT_MAX)
2821 message_size = (int)size;
2824 /* If this session was initiated with EHLO and accept_8bitmime is set,
2825 Exim will have indicated that it supports the BODY=8BITMIME option. In
2826 fact, it does not support this according to the RFCs, in that it does not
2827 take any special action for forwarding messages containing 8-bit
2828 characters. That is why accept_8bitmime is not the default setting, but
2829 some sites want the action that is provided. We recognize both "8BITMIME"
2830 and "7BIT" as body types, but take no action. */
2832 else if (accept_8bitmime && strcmpic(name, US"BODY") == 0 &&
2833 (strcmpic(value, US"8BITMIME") == 0 ||
2834 strcmpic(value, US"7BIT") == 0)) {}
2836 /* Handle the AUTH extension. If the value given is not "<>" and either
2837 the ACL says "yes" or there is no ACL but the sending host is
2838 authenticated, we set it up as the authenticated sender. However, if the
2839 authenticator set a condition to be tested, we ignore AUTH on MAIL unless
2840 the condition is met. The value of AUTH is an xtext, which means that +,
2841 = and cntrl chars are coded in hex; however "<>" is unaffected by this
2844 else if (strcmpic(name, US"AUTH") == 0)
2846 if (Ustrcmp(value, "<>") != 0)
2851 if (auth_xtextdecode(value, &authenticated_sender) < 0)
2853 /* Put back terminator overrides for error message */
2856 done = synprot_error(L_smtp_syntax_error, 501, NULL,
2857 US"invalid data for AUTH");
2861 if (acl_smtp_mailauth == NULL)
2863 ignore_msg = US"client not authenticated";
2864 rc = (sender_host_authenticated != NULL)? OK : FAIL;
2868 ignore_msg = US"rejected by ACL";
2869 rc = acl_check(ACL_WHERE_MAILAUTH, NULL, acl_smtp_mailauth,
2870 &user_msg, &log_msg);
2876 if (authenticated_by == NULL ||
2877 authenticated_by->mail_auth_condition == NULL ||
2878 expand_check_condition(authenticated_by->mail_auth_condition,
2879 authenticated_by->name, US"authenticator"))
2880 break; /* Accept the AUTH */
2882 ignore_msg = US"server_mail_auth_condition failed";
2883 if (authenticated_id != NULL)
2884 ignore_msg = string_sprintf("%s: authenticated ID=\"%s\"",
2885 ignore_msg, authenticated_id);
2890 authenticated_sender = NULL;
2891 log_write(0, LOG_MAIN, "ignoring AUTH=%s from %s (%s)",
2892 value, host_and_ident(TRUE), ignore_msg);
2895 /* Should only get DEFER or ERROR here. Put back terminator
2896 overrides for error message */
2901 (void)smtp_handle_acl_fail(ACL_WHERE_MAILAUTH, rc, user_msg,
2908 /* Unknown option. Stick back the terminator characters and break
2909 the loop. An error for a malformed address will occur. */
2919 /* If we have passed the threshold for rate limiting, apply the current
2920 delay, and update it for next time, provided this is a limited host. */
2922 if (smtp_mailcmd_count > smtp_rlm_threshold &&
2923 verify_check_host(&smtp_ratelimit_hosts) == OK)
2925 DEBUG(D_receive) debug_printf("rate limit MAIL: delay %.3g sec\n",
2926 smtp_delay_mail/1000.0);
2927 millisleep((int)smtp_delay_mail);
2928 smtp_delay_mail *= smtp_rlm_factor;
2929 if (smtp_delay_mail > (double)smtp_rlm_limit)
2930 smtp_delay_mail = (double)smtp_rlm_limit;
2933 /* Now extract the address, first applying any SMTP-time rewriting. The
2934 TRUE flag allows "<>" as a sender address. */
2936 raw_sender = ((rewrite_existflags & rewrite_smtp) != 0)?
2937 rewrite_one(smtp_cmd_argument, rewrite_smtp, NULL, FALSE, US"",
2938 global_rewrite_rules) : smtp_cmd_argument;
2940 /* rfc821_domains = TRUE; << no longer needed */
2942 parse_extract_address(raw_sender, &errmess, &start, &end, &sender_domain,
2944 /* rfc821_domains = FALSE; << no longer needed */
2946 if (raw_sender == NULL)
2948 done = synprot_error(L_smtp_syntax_error, 501, smtp_cmd_argument, errmess);
2952 sender_address = raw_sender;
2954 /* If there is a configured size limit for mail, check that this message
2955 doesn't exceed it. The check is postponed to this point so that the sender
2958 if (thismessage_size_limit > 0 && message_size > thismessage_size_limit)
2960 smtp_printf("552 Message size exceeds maximum permitted\r\n");
2961 log_write(L_size_reject,
2962 LOG_MAIN|LOG_REJECT, "rejected MAIL FROM:<%s> %s: "
2963 "message too big: size%s=%d max=%d",
2965 host_and_ident(TRUE),
2966 (message_size == INT_MAX)? ">" : "",
2968 thismessage_size_limit);
2969 sender_address = NULL;
2973 /* Check there is enough space on the disk unless configured not to.
2974 When smtp_check_spool_space is set, the check is for thismessage_size_limit
2975 plus the current message - i.e. we accept the message only if it won't
2976 reduce the space below the threshold. Add 5000 to the size to allow for
2977 overheads such as the Received: line and storing of recipients, etc.
2978 By putting the check here, even when SIZE is not given, it allow VRFY
2979 and EXPN etc. to be used when space is short. */
2981 if (!receive_check_fs(
2982 (smtp_check_spool_space && message_size >= 0)?
2983 message_size + 5000 : 0))
2985 smtp_printf("452 Space shortage, please try later\r\n");
2986 sender_address = NULL;
2990 /* If sender_address is unqualified, reject it, unless this is a locally
2991 generated message, or the sending host or net is permitted to send
2992 unqualified addresses - typically local machines behaving as MUAs -
2993 in which case just qualify the address. The flag is set above at the start
2994 of the SMTP connection. */
2996 if (sender_domain == 0 && sender_address[0] != 0)
2998 if (allow_unqualified_sender)
3000 sender_domain = Ustrlen(sender_address) + 1;
3001 sender_address = rewrite_address_qualify(sender_address, FALSE);
3002 DEBUG(D_receive) debug_printf("unqualified address %s accepted\n",
3007 smtp_printf("501 %s: sender address must contain a domain\r\n",
3009 log_write(L_smtp_syntax_error,
3010 LOG_MAIN|LOG_REJECT,
3011 "unqualified sender rejected: <%s> %s%s",
3013 host_and_ident(TRUE),
3015 sender_address = NULL;
3020 /* Apply an ACL check if one is defined, before responding */
3022 rc = (acl_smtp_mail == NULL)? OK :
3023 acl_check(ACL_WHERE_MAIL, NULL, acl_smtp_mail, &user_msg, &log_msg);
3025 if (rc == OK || rc == DISCARD)
3027 smtp_printf("250 OK\r\n");
3028 smtp_delay_rcpt = smtp_rlr_base;
3029 recipients_discarded = (rc == DISCARD);
3030 was_rej_mail = FALSE;
3035 done = smtp_handle_acl_fail(ACL_WHERE_MAIL, rc, user_msg, log_msg);
3036 sender_address = NULL;
3041 /* The RCPT command requires an address as an operand. All we do
3042 here is to parse it for syntactic correctness. There may be any number
3043 of RCPT commands, specifying multiple senders. We build them all into
3044 a data structure that is in argc/argv format. The start/end values
3045 given by parse_extract_address are not used, as we keep only the
3046 extracted address. */
3052 /* There must be a sender address; if the sender was rejected and
3053 pipelining was advertised, we assume the client was pipelining, and do not
3054 count this as a protocol error. Reset was_rej_mail so that further RCPTs
3055 get the same treatment. */
3057 if (sender_address == NULL)
3059 if (pipelining_advertised && last_was_rej_mail)
3061 smtp_printf("503 sender not yet given\r\n");
3062 was_rej_mail = TRUE;
3066 done = synprot_error(L_smtp_protocol_error, 503, NULL,
3067 US"sender not yet given");
3068 was_rcpt = FALSE; /* Not a valid RCPT */
3074 /* Check for an operand */
3076 if (smtp_cmd_argument[0] == 0)
3078 done = synprot_error(L_smtp_syntax_error, 501, NULL,
3079 US"RCPT must have an address operand");
3084 /* Apply SMTP rewriting then extract the working address. Don't allow "<>"
3085 as a recipient address */
3087 recipient = ((rewrite_existflags & rewrite_smtp) != 0)?
3088 rewrite_one(smtp_cmd_argument, rewrite_smtp, NULL, FALSE, US"",
3089 global_rewrite_rules) : smtp_cmd_argument;
3091 /* rfc821_domains = TRUE; << no longer needed */
3092 recipient = parse_extract_address(recipient, &errmess, &start, &end,
3093 &recipient_domain, FALSE);
3094 /* rfc821_domains = FALSE; << no longer needed */
3096 if (recipient == NULL)
3098 done = synprot_error(L_smtp_syntax_error, 501, smtp_cmd_argument, errmess);
3103 /* If the recipient address is unqualified, reject it, unless this is a
3104 locally generated message. However, unqualified addresses are permitted
3105 from a configured list of hosts and nets - typically when behaving as
3106 MUAs rather than MTAs. Sad that SMTP is used for both types of traffic,
3107 really. The flag is set at the start of the SMTP connection.
3109 RFC 1123 talks about supporting "the reserved mailbox postmaster"; I always
3110 assumed this meant "reserved local part", but the revision of RFC 821 and
3111 friends now makes it absolutely clear that it means *mailbox*. Consequently
3112 we must always qualify this address, regardless. */
3114 if (recipient_domain == 0)
3116 if (allow_unqualified_recipient ||
3117 strcmpic(recipient, US"postmaster") == 0)
3119 DEBUG(D_receive) debug_printf("unqualified address %s accepted\n",
3121 recipient_domain = Ustrlen(recipient) + 1;
3122 recipient = rewrite_address_qualify(recipient, TRUE);
3127 smtp_printf("501 %s: recipient address must contain a domain\r\n",
3129 log_write(L_smtp_syntax_error,
3130 LOG_MAIN|LOG_REJECT, "unqualified recipient rejected: "
3131 "<%s> %s%s", recipient, host_and_ident(TRUE),
3137 /* Check maximum allowed */
3139 if (rcpt_count > recipients_max && recipients_max > 0)
3141 if (recipients_max_reject)
3144 smtp_printf("552 too many recipients\r\n");
3146 log_write(0, LOG_MAIN|LOG_REJECT, "too many recipients: message "
3147 "rejected: sender=<%s> %s", sender_address, host_and_ident(TRUE));
3152 smtp_printf("452 too many recipients\r\n");
3154 log_write(0, LOG_MAIN|LOG_REJECT, "too many recipients: excess "
3155 "temporarily rejected: sender=<%s> %s", sender_address,
3156 host_and_ident(TRUE));
3163 /* If we have passed the threshold for rate limiting, apply the current
3164 delay, and update it for next time, provided this is a limited host. */
3166 if (rcpt_count > smtp_rlr_threshold &&
3167 verify_check_host(&smtp_ratelimit_hosts) == OK)
3169 DEBUG(D_receive) debug_printf("rate limit RCPT: delay %.3g sec\n",
3170 smtp_delay_rcpt/1000.0);
3171 millisleep((int)smtp_delay_rcpt);
3172 smtp_delay_rcpt *= smtp_rlr_factor;
3173 if (smtp_delay_rcpt > (double)smtp_rlr_limit)
3174 smtp_delay_rcpt = (double)smtp_rlr_limit;
3177 /* If the MAIL ACL discarded all the recipients, we bypass ACL checking
3178 for them. Otherwise, check the access control list for this recipient. */
3180 rc = recipients_discarded? DISCARD :
3181 acl_check(ACL_WHERE_RCPT, recipient, acl_smtp_rcpt, &user_msg, &log_msg);
3183 /* The ACL was happy */
3187 smtp_printf("250 Accepted\r\n");
3188 receive_add_recipient(recipient, -1);
3191 /* The recipient was discarded */
3193 else if (rc == DISCARD)
3195 smtp_printf("250 Accepted\r\n");
3198 log_write(0, LOG_MAIN|LOG_REJECT, "%s F=<%s> rejected RCPT %s: "
3199 "discarded by %s ACL%s%s", host_and_ident(TRUE),
3200 (sender_address_unrewritten != NULL)?
3201 sender_address_unrewritten : sender_address,
3202 smtp_cmd_argument, recipients_discarded? "MAIL" : "RCPT",
3203 (log_msg == NULL)? US"" : US": ",
3204 (log_msg == NULL)? US"" : log_msg);
3207 /* Either the ACL failed the address, or it was deferred. */
3211 if (rc == FAIL) rcpt_fail_count++; else rcpt_defer_count++;
3212 done = smtp_handle_acl_fail(ACL_WHERE_RCPT, rc, user_msg, log_msg);
3217 /* The DATA command is legal only if it follows successful MAIL FROM
3218 and RCPT TO commands. However, if pipelining is advertised, a bad DATA is
3219 not counted as a protocol error if it follows RCPT (which must have been
3220 rejected if there are no recipients.) This function is complete when a
3221 valid DATA command is encountered.
3223 Note concerning the code used: RFC 2821 says this:
3225 - If there was no MAIL, or no RCPT, command, or all such commands
3226 were rejected, the server MAY return a "command out of sequence"
3227 (503) or "no valid recipients" (554) reply in response to the
3230 The example in the pipelining RFC 2920 uses 554, but I use 503 here
3231 because it is the same whether pipelining is in use or not. */
3234 if (!discarded && recipients_count <= 0)
3236 if (pipelining_advertised && last_was_rcpt)
3237 smtp_printf("503 valid RCPT command must precede DATA\r\n");
3239 done = synprot_error(L_smtp_protocol_error, 503, NULL,
3240 US"valid RCPT command must precede DATA");
3244 if (toomany && recipients_max_reject)
3246 sender_address = NULL; /* This will allow a new MAIL without RSET */
3247 sender_address_unrewritten = NULL;
3248 smtp_printf("554 Too many recipients\r\n");
3252 if (acl_smtp_predata == NULL) rc = OK; else
3254 enable_dollar_recipients = TRUE;
3255 rc = acl_check(ACL_WHERE_PREDATA, NULL, acl_smtp_predata, &user_msg,
3257 enable_dollar_recipients = FALSE;
3262 smtp_printf("354 Enter message, ending with \".\" on a line by itself\r\n");
3264 message_ended = END_NOTENDED; /* Indicate in middle of data */
3267 /* Either the ACL failed the address, or it was deferred. */
3270 done = smtp_handle_acl_fail(ACL_WHERE_PREDATA, rc, user_msg, log_msg);
3276 rc = acl_check(ACL_WHERE_VRFY, NULL, acl_smtp_vrfy, &user_msg, &log_msg);
3278 done = smtp_handle_acl_fail(ACL_WHERE_VRFY, rc, user_msg, log_msg);
3284 /* rfc821_domains = TRUE; << no longer needed */
3285 address = parse_extract_address(smtp_cmd_argument, &errmess, &start, &end,
3286 &recipient_domain, FALSE);
3287 /* rfc821_domains = FALSE; << no longer needed */
3289 if (address == NULL)
3290 s = string_sprintf("501 %s", errmess);
3293 address_item *addr = deliver_make_addr(address, FALSE);
3294 switch(verify_address(addr, NULL, vopt_is_recipient | vopt_qualify, -1,
3295 -1, -1, NULL, NULL, NULL))
3298 s = string_sprintf("250 <%s> is deliverable", address);
3302 s = (addr->user_message != NULL)?
3303 string_sprintf("451 <%s> %s", address, addr->user_message) :
3304 string_sprintf("451 Cannot resolve <%s> at this time", address);
3308 s = (addr->user_message != NULL)?
3309 string_sprintf("550 <%s> %s", address, addr->user_message) :
3310 string_sprintf("550 <%s> is not deliverable", address);
3311 log_write(0, LOG_MAIN, "VRFY failed for %s %s",
3312 smtp_cmd_argument, host_and_ident(TRUE));
3317 smtp_printf("%s\r\n", s);
3323 rc = acl_check(ACL_WHERE_EXPN, NULL, acl_smtp_expn, &user_msg, &log_msg);
3325 done = smtp_handle_acl_fail(ACL_WHERE_EXPN, rc, user_msg, log_msg);
3328 BOOL save_log_testing_mode = log_testing_mode;
3329 address_test_mode = log_testing_mode = TRUE;
3330 (void) verify_address(deliver_make_addr(smtp_cmd_argument, FALSE),
3331 smtp_out, vopt_is_recipient | vopt_qualify | vopt_expn, -1, -1, -1,
3333 address_test_mode = FALSE;
3334 log_testing_mode = save_log_testing_mode; /* true for -bh */
3342 if (!tls_advertised)
3344 done = synprot_error(L_smtp_protocol_error, 503, NULL,
3345 US"STARTTLS command used when not advertised");
3349 /* Apply an ACL check if one is defined */
3351 if (acl_smtp_starttls != NULL)
3353 rc = acl_check(ACL_WHERE_STARTTLS, NULL, acl_smtp_starttls, &user_msg,
3357 done = smtp_handle_acl_fail(ACL_WHERE_STARTTLS, rc, user_msg, log_msg);
3362 /* RFC 2487 is not clear on when this command may be sent, though it
3363 does state that all information previously obtained from the client
3364 must be discarded if a TLS session is started. It seems reasonble to
3365 do an implied RSET when STARTTLS is received. */
3367 incomplete_transaction_log(US"STARTTLS");
3368 smtp_reset(reset_point);
3370 cmd_list[CMD_LIST_STARTTLS].is_mail_cmd = FALSE;
3372 /* Attempt to start up a TLS session, and if successful, discard all
3373 knowledge that was obtained previously. At least, that's what the RFC says,
3374 and that's what happens by default. However, in order to work round YAEB,
3375 there is an option to remember the esmtp state. Sigh.
3377 We must allow for an extra EHLO command and an extra AUTH command after
3378 STARTTLS that don't add to the nonmail command count. */
3380 if ((rc = tls_server_start(tls_require_ciphers)) == OK)
3382 if (!tls_remember_esmtp)
3383 helo_seen = esmtp = auth_advertised = pipelining_advertised = FALSE;
3384 cmd_list[CMD_LIST_EHLO].is_mail_cmd = TRUE;
3385 cmd_list[CMD_LIST_AUTH].is_mail_cmd = TRUE;
3386 if (sender_helo_name != NULL)
3388 store_free(sender_helo_name);
3389 sender_helo_name = NULL;
3390 host_build_sender_fullhost(); /* Rebuild */
3391 set_process_info("handling incoming TLS connection from %s",
3392 host_and_ident(FALSE));
3394 received_protocol = (esmtp?
3395 protocols[pextend + pcrpted +
3396 ((sender_host_authenticated != NULL)? pauthed : 0)]
3398 protocols[pnormal + pcrpted])
3400 ((sender_host_address != NULL)? pnlocal : 0);
3402 sender_host_authenticated = NULL;
3403 authenticated_id = NULL;
3404 sync_cmd_limit = NON_SYNC_CMD_NON_PIPELINING;
3405 DEBUG(D_tls) debug_printf("TLS active\n");
3406 break; /* Successful STARTTLS */
3409 /* Some local configuration problem was discovered before actually trying
3410 to do a TLS handshake; give a temporary error. */
3412 else if (rc == DEFER)
3414 smtp_printf("454 TLS currently unavailable\r\n");
3418 /* Hard failure. Reject everything except QUIT or closed connection. One
3419 cause for failure is a nested STARTTLS, in which case tls_active remains
3420 set, but we must still reject all incoming commands. */
3422 DEBUG(D_tls) debug_printf("TLS failed to start\n");
3425 switch(smtp_read_command(FALSE))
3428 log_write(L_smtp_connection, LOG_MAIN, "%s closed by EOF",
3429 smtp_get_connection_info());
3434 smtp_printf("221 %s closing connection\r\n", smtp_active_hostname);
3435 log_write(L_smtp_connection, LOG_MAIN, "%s closed by QUIT",
3436 smtp_get_connection_info());
3441 smtp_printf("554 Security failure\r\n");
3450 /* The ACL for QUIT is provided for gathering statistical information or
3451 similar; it does not affect the response code, but it can supply a custom
3455 incomplete_transaction_log(US"QUIT");
3457 if (acl_smtp_quit != NULL)
3459 rc = acl_check(ACL_WHERE_QUIT, NULL, acl_smtp_quit,&user_msg,&log_msg);
3461 log_write(0, LOG_MAIN|LOG_PANIC, "ACL for QUIT returned ERROR: %s",
3464 else user_msg = NULL;
3466 if (user_msg == NULL)
3467 smtp_printf("221 %s closing connection\r\n", smtp_active_hostname);
3469 smtp_printf("221 %s\r\n", user_msg);
3476 log_write(L_smtp_connection, LOG_MAIN, "%s closed by QUIT",
3477 smtp_get_connection_info());
3482 incomplete_transaction_log(US"RSET");
3483 smtp_reset(reset_point);
3485 smtp_printf("250 Reset OK\r\n");
3486 cmd_list[CMD_LIST_RSET].is_mail_cmd = FALSE;
3491 smtp_printf("250 OK\r\n");
3495 /* Show ETRN/EXPN/VRFY if there's
3496 an ACL for checking hosts; if actually used, a check will be done for
3500 smtp_printf("214-Commands supported:\r\n");
3504 Ustrcat(buffer, " AUTH");
3506 Ustrcat(buffer, " STARTTLS");
3508 Ustrcat(buffer, " HELO EHLO MAIL RCPT DATA");
3509 Ustrcat(buffer, " NOOP QUIT RSET HELP");
3510 if (acl_smtp_etrn != NULL) Ustrcat(buffer, " ETRN");
3511 if (acl_smtp_expn != NULL) Ustrcat(buffer, " EXPN");
3512 if (acl_smtp_vrfy != NULL) Ustrcat(buffer, " VRFY");
3513 smtp_printf("214%s\r\n", buffer);
3519 incomplete_transaction_log(US"connection lost");
3520 smtp_printf("421 %s lost input connection\r\n", smtp_active_hostname);
3522 /* Don't log by default unless in the middle of a message, as some mailers
3523 just drop the call rather than sending QUIT, and it clutters up the logs.
3526 if (sender_address != NULL || recipients_count > 0)
3527 log_write(L_lost_incoming_connection,
3529 "unexpected %s while reading SMTP command from %s%s",
3530 sender_host_unknown? "EOF" : "disconnection",
3531 host_and_ident(FALSE), smtp_read_error);
3533 else log_write(L_smtp_connection, LOG_MAIN, "%s lost%s",
3534 smtp_get_connection_info(), smtp_read_error);
3541 if (sender_address != NULL)
3543 done = synprot_error(L_smtp_protocol_error, 503, NULL,
3544 US"ETRN is not permitted inside a transaction");
3548 log_write(L_etrn, LOG_MAIN, "ETRN %s received from %s", smtp_cmd_argument,
3549 host_and_ident(FALSE));
3551 rc = acl_check(ACL_WHERE_ETRN, NULL, acl_smtp_etrn, &user_msg, &log_msg);
3554 done = smtp_handle_acl_fail(ACL_WHERE_ETRN, rc, user_msg, log_msg);
3558 /* Compute the serialization key for this command. */
3560 etrn_serialize_key = string_sprintf("etrn-%s\n", smtp_cmd_argument);
3562 /* If a command has been specified for running as a result of ETRN, we
3563 permit any argument to ETRN. If not, only the # standard form is permitted,
3564 since that is strictly the only kind of ETRN that can be implemented
3565 according to the RFC. */
3567 if (smtp_etrn_command != NULL)
3571 etrn_command = smtp_etrn_command;
3572 deliver_domain = smtp_cmd_argument;
3573 rc = transport_set_up_command(&argv, smtp_etrn_command, TRUE, 0, NULL,
3574 US"ETRN processing", &error);
3575 deliver_domain = NULL;
3578 log_write(0, LOG_MAIN|LOG_PANIC, "failed to set up ETRN command: %s",
3580 smtp_printf("458 Internal failure\r\n");
3585 /* Else set up to call Exim with the -R option. */
3589 if (*smtp_cmd_argument++ != '#')
3591 done = synprot_error(L_smtp_syntax_error, 501, NULL,
3592 US"argument must begin with #");
3595 etrn_command = US"exim -R";
3596 argv = child_exec_exim(CEE_RETURN_ARGV, TRUE, NULL, TRUE, 2, US"-R",
3600 /* If we are host-testing, don't actually do anything. */
3606 debug_printf("ETRN command is: %s\n", etrn_command);
3607 debug_printf("ETRN command execution skipped\n");
3609 smtp_printf("250 OK\r\n");
3614 /* If ETRN queue runs are to be serialized, check the database to
3615 ensure one isn't already running. */
3617 if (smtp_etrn_serialize && !enq_start(etrn_serialize_key))
3619 smtp_printf("458 Already processing %s\r\n", smtp_cmd_argument);
3623 /* Fork a child process and run the command. We don't want to have to
3624 wait for the process at any point, so set SIGCHLD to SIG_IGN before
3625 forking. It should be set that way anyway for external incoming SMTP,
3626 but we save and restore to be tidy. If serialization is required, we
3627 actually run the command in yet another process, so we can wait for it
3628 to complete and then remove the serialization lock. */
3630 oldsignal = signal(SIGCHLD, SIG_IGN);
3632 if ((pid = fork()) == 0)
3634 smtp_input = FALSE; /* This process is not associated with the */
3635 (void)fclose(smtp_in); /* SMTP call any more. */
3636 (void)fclose(smtp_out);
3638 signal(SIGCHLD, SIG_DFL); /* Want to catch child */
3640 /* If not serializing, do the exec right away. Otherwise, fork down
3641 into another process. */
3643 if (!smtp_etrn_serialize || (pid = fork()) == 0)
3645 DEBUG(D_exec) debug_print_argv(argv);
3646 exim_nullstd(); /* Ensure std{in,out,err} exist */
3647 execv(CS argv[0], (char *const *)argv);
3648 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "exec of \"%s\" (ETRN) failed: %s",
3649 etrn_command, strerror(errno));
3650 _exit(EXIT_FAILURE); /* paranoia */
3653 /* Obey this if smtp_serialize and the 2nd fork yielded non-zero. That
3654 is, we are in the first subprocess, after forking again. All we can do
3655 for a failing fork is to log it. Otherwise, wait for the 2nd process to
3656 complete, before removing the serialization. */
3659 log_write(0, LOG_MAIN|LOG_PANIC, "2nd fork for serialized ETRN "
3660 "failed: %s", strerror(errno));
3664 DEBUG(D_any) debug_printf("waiting for serialized ETRN process %d\n",
3666 (void)wait(&status);
3667 DEBUG(D_any) debug_printf("serialized ETRN process %d ended\n",
3671 enq_end(etrn_serialize_key);
3672 _exit(EXIT_SUCCESS);
3675 /* Back in the top level SMTP process. Check that we started a subprocess
3676 and restore the signal state. */
3680 log_write(0, LOG_MAIN|LOG_PANIC, "fork of process for ETRN failed: %s",
3682 smtp_printf("458 Unable to fork process\r\n");
3683 if (smtp_etrn_serialize) enq_end(etrn_serialize_key);
3685 else smtp_printf("250 OK\r\n");
3687 signal(SIGCHLD, oldsignal);
3692 done = synprot_error(L_smtp_syntax_error, 501, NULL,
3693 US"unexpected argument data");
3697 /* This currently happens only for NULLs, but could be extended. */
3700 done = synprot_error(L_smtp_syntax_error, 0, NULL, /* Just logs */
3701 US"NULL character(s) present (shown as '?')");
3702 smtp_printf("501 NULL characters are not allowed in SMTP commands\r\n");
3707 if (smtp_inend >= smtp_inbuffer + in_buffer_size)
3708 smtp_inend = smtp_inbuffer + in_buffer_size - 1;
3709 c = smtp_inend - smtp_inptr;
3710 if (c > 150) c = 150;
3712 incomplete_transaction_log(US"sync failure");
3713 log_write(0, LOG_MAIN|LOG_REJECT, "SMTP protocol synchronization error "
3714 "(next input sent too soon: pipelining was%s advertised): "
3715 "rejected \"%s\" %s next input=\"%s\"",
3716 pipelining_advertised? "" : " not",
3717 smtp_cmd_buffer, host_and_ident(TRUE),
3718 string_printing(smtp_inptr));
3719 smtp_printf("554 SMTP synchronization error\r\n");
3720 done = 1; /* Pretend eof - drops connection */
3724 case TOO_MANY_NONMAIL_CMD:
3725 incomplete_transaction_log(US"too many non-mail commands");
3726 log_write(0, LOG_MAIN|LOG_REJECT, "SMTP call from %s dropped: too many "
3727 "nonmail commands (last was \"%.*s\")", host_and_ident(FALSE),
3728 smtp_cmd_argument - smtp_cmd_buffer, smtp_cmd_buffer);
3729 smtp_printf("554 Too many nonmail commands\r\n");
3730 done = 1; /* Pretend eof - drops connection */
3735 if (unknown_command_count++ >= smtp_max_unknown_commands)
3737 log_write(L_smtp_syntax_error, LOG_MAIN,
3738 "SMTP syntax error in \"%s\" %s %s",
3739 string_printing(smtp_cmd_buffer), host_and_ident(TRUE),
3740 US"unrecognized command");
3741 incomplete_transaction_log(US"unrecognized command");
3742 smtp_printf("500 Too many unrecognized commands\r\n");
3744 log_write(0, LOG_MAIN|LOG_REJECT, "SMTP call from %s dropped: too many "
3745 "unrecognized commands (last was \"%s\")", host_and_ident(FALSE),
3749 done = synprot_error(L_smtp_syntax_error, 500, NULL,
3750 US"unrecognized command");
3754 /* This label is used by goto's inside loops that want to break out to
3755 the end of the command-processing loop. */
3758 last_was_rej_mail = was_rej_mail; /* Remember some last commands for */
3759 last_was_rcpt = was_rcpt; /* protocol error handling */
3763 return done - 2; /* Convert yield values */
3766 /* End of smtp_in.c */