1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
5 /* Copyright (c) University of Cambridge 1995 - 2018 */
6 /* Copyright (c) The Exim Maintainers 2020 */
7 /* See the file NOTICE for conditions of use and distribution. */
9 /* 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;
34 uschar *tcp_wrappers_name;
38 /* Size of buffer for reading SMTP commands. We used to use 512, as defined
39 by RFC 821. However, RFC 1869 specifies that this must be increased for SMTP
40 commands that accept arguments, and this in particular applies to AUTH, where
41 the data can be quite long. More recently this value was 2048 in Exim;
42 however, RFC 4954 (circa 2007) recommends 12288 bytes to handle AUTH. Clients
43 such as Thunderbird will send an AUTH with an initial-response for GSSAPI.
44 The maximum size of a Kerberos ticket under Windows 2003 is 12000 bytes, and
45 we need room to handle large base64-encoded AUTHs for GSSAPI.
48 #define SMTP_CMD_BUFFER_SIZE 16384
50 /* Size of buffer for reading SMTP incoming packets */
52 #define IN_BUFFER_SIZE 8192
54 /* Structure for SMTP command list */
61 short int is_mail_cmd;
64 /* Codes for identifying commands. We order them so that those that come first
65 are those for which synchronization is always required. Checking this can help
69 /* These commands are required to be synchronized, i.e. to be the last in a
70 block of commands when pipelining. */
72 HELO_CMD, EHLO_CMD, DATA_CMD, /* These are listed in the pipelining */
73 VRFY_CMD, EXPN_CMD, NOOP_CMD, /* RFC as requiring synchronization */
74 ETRN_CMD, /* This by analogy with TURN from the RFC */
75 STARTTLS_CMD, /* Required by the STARTTLS RFC */
76 TLS_AUTH_CMD, /* auto-command at start of SSL */
78 /* This is a dummy to identify the non-sync commands when pipelining */
80 NON_SYNC_CMD_PIPELINING,
82 /* These commands need not be synchronized when pipelining */
84 MAIL_CMD, RCPT_CMD, RSET_CMD,
86 /* This is a dummy to identify the non-sync commands when not pipelining */
88 NON_SYNC_CMD_NON_PIPELINING,
90 /* RFC3030 section 2: "After all MAIL and RCPT responses are collected and
91 processed the message is sent using a series of BDAT commands"
92 implies that BDAT should be synchronized. However, we see Google, at least,
93 sending MAIL,RCPT,BDAT-LAST in a single packet, clearly not waiting for
94 processing of the RCPT response(s). We shall do the same, and not require
95 synch for BDAT. Worse, as the chunk may (very likely will) follow the
96 command-header in the same packet we cannot do the usual "is there any
97 follow-on data after the command line" even for non-pipeline mode.
98 So we'll need an explicit check after reading the expected chunk amount
99 when non-pipe, before sending the ACK. */
103 /* I have been unable to find a statement about the use of pipelining
104 with AUTH, so to be on the safe side it is here, though I kind of feel
105 it should be up there with the synchronized commands. */
109 /* I'm not sure about these, but I don't think they matter. */
114 PROXY_FAIL_IGNORE_CMD,
117 /* These are specials that don't correspond to actual commands */
119 EOF_CMD, OTHER_CMD, BADARG_CMD, BADCHAR_CMD, BADSYN_CMD,
120 TOO_MANY_NONMAIL_CMD };
123 /* This is a convenience macro for adding the identity of an SMTP command
124 to the circular buffer that holds a list of the last n received. */
127 smtp_connection_had[smtp_ch_index++] = n; \
128 if (smtp_ch_index >= SMTP_HBUFF_SIZE) smtp_ch_index = 0
131 /*************************************************
132 * Local static variables *
133 *************************************************/
136 BOOL auth_advertised :1;
138 BOOL tls_advertised :1;
140 BOOL dsn_advertised :1;
142 BOOL helo_verify_required :1;
145 BOOL helo_accept_junk :1;
146 #ifndef DISABLE_PIPE_CONNECT
147 BOOL pipe_connect_acceptable :1;
149 BOOL rcpt_smtp_response_same :1;
150 BOOL rcpt_in_progress :1;
151 BOOL smtp_exit_function_called :1;
153 BOOL smtputf8_advertised :1;
156 .helo_verify_required = FALSE,
157 .helo_verify = FALSE,
158 .smtp_exit_function_called = FALSE,
161 static auth_instance *authenticated_by;
162 static int count_nonmail;
163 static int nonmail_command_count;
164 static int synprot_error_count;
165 static int unknown_command_count;
166 static int sync_cmd_limit;
167 static int smtp_write_error = 0;
169 static uschar *rcpt_smtp_response;
170 static uschar *smtp_data_buffer;
171 static uschar *smtp_cmd_data;
173 /* We need to know the position of RSET, HELO, EHLO, AUTH, and STARTTLS. Their
174 final fields of all except AUTH are forced TRUE at the start of a new message
175 setup, to allow one of each between messages that is not counted as a nonmail
176 command. (In fact, only one of HELO/EHLO is not counted.) Also, we have to
177 allow a new EHLO after starting up TLS.
179 AUTH is "falsely" labelled as a mail command initially, so that it doesn't get
180 counted. However, the flag is changed when AUTH is received, so that multiple
181 failing AUTHs will eventually hit the limit. After a successful AUTH, another
182 AUTH is already forbidden. After a TLS session is started, AUTH's flag is again
183 forced TRUE, to allow for the re-authentication that can happen at that point.
185 QUIT is also "falsely" labelled as a mail command so that it doesn't up the
186 count of non-mail commands and possibly provoke an error.
188 tls_auth is a pseudo-command, never expected in input. It is activated
189 on TLS startup and looks for a tls authenticator. */
191 static smtp_cmd_list cmd_list[] = {
192 /* name len cmd has_arg is_mail_cmd */
194 { "rset", sizeof("rset")-1, RSET_CMD, FALSE, FALSE }, /* First */
195 { "helo", sizeof("helo")-1, HELO_CMD, TRUE, FALSE },
196 { "ehlo", sizeof("ehlo")-1, EHLO_CMD, TRUE, FALSE },
197 { "auth", sizeof("auth")-1, AUTH_CMD, TRUE, TRUE },
199 { "starttls", sizeof("starttls")-1, STARTTLS_CMD, FALSE, FALSE },
200 { "tls_auth", 0, TLS_AUTH_CMD, FALSE, FALSE },
203 /* If you change anything above here, also fix the definitions below. */
205 { "mail from:", sizeof("mail from:")-1, MAIL_CMD, TRUE, TRUE },
206 { "rcpt to:", sizeof("rcpt to:")-1, RCPT_CMD, TRUE, TRUE },
207 { "data", sizeof("data")-1, DATA_CMD, FALSE, TRUE },
208 { "bdat", sizeof("bdat")-1, BDAT_CMD, TRUE, TRUE },
209 { "quit", sizeof("quit")-1, QUIT_CMD, FALSE, TRUE },
210 { "noop", sizeof("noop")-1, NOOP_CMD, TRUE, FALSE },
211 { "etrn", sizeof("etrn")-1, ETRN_CMD, TRUE, FALSE },
212 { "vrfy", sizeof("vrfy")-1, VRFY_CMD, TRUE, FALSE },
213 { "expn", sizeof("expn")-1, EXPN_CMD, TRUE, FALSE },
214 { "help", sizeof("help")-1, HELP_CMD, TRUE, FALSE }
217 static smtp_cmd_list *cmd_list_end =
218 cmd_list + sizeof(cmd_list)/sizeof(smtp_cmd_list);
220 #define CMD_LIST_RSET 0
221 #define CMD_LIST_HELO 1
222 #define CMD_LIST_EHLO 2
223 #define CMD_LIST_AUTH 3
224 #define CMD_LIST_STARTTLS 4
225 #define CMD_LIST_TLS_AUTH 5
227 /* This list of names is used for performing the smtp_no_mail logging action.
228 It must be kept in step with the SCH_xxx enumerations. */
230 uschar * smtp_names[] =
232 US"NONE", US"AUTH", US"DATA", US"BDAT", US"EHLO", US"ETRN", US"EXPN",
233 US"HELO", US"HELP", US"MAIL", US"NOOP", US"QUIT", US"RCPT", US"RSET",
234 US"STARTTLS", US"VRFY" };
236 static uschar *protocols_local[] = {
237 US"local-smtp", /* HELO */
238 US"local-smtps", /* The rare case EHLO->STARTTLS->HELO */
239 US"local-esmtp", /* EHLO */
240 US"local-esmtps", /* EHLO->STARTTLS->EHLO */
241 US"local-esmtpa", /* EHLO->AUTH */
242 US"local-esmtpsa" /* EHLO->STARTTLS->EHLO->AUTH */
244 static uschar *protocols[] = {
246 US"smtps", /* The rare case EHLO->STARTTLS->HELO */
247 US"esmtp", /* EHLO */
248 US"esmtps", /* EHLO->STARTTLS->EHLO */
249 US"esmtpa", /* EHLO->AUTH */
250 US"esmtpsa" /* EHLO->STARTTLS->EHLO->AUTH */
255 #define pcrpted 1 /* added to pextend or pnormal */
256 #define pauthed 2 /* added to pextend */
258 /* Sanity check and validate optional args to MAIL FROM: envelope */
261 ENV_MAIL_OPT_SIZE, ENV_MAIL_OPT_BODY, ENV_MAIL_OPT_AUTH,
265 ENV_MAIL_OPT_RET, ENV_MAIL_OPT_ENVID,
271 uschar * name; /* option requested during MAIL cmd */
272 int value; /* enum type */
273 BOOL need_value; /* TRUE requires value (name=value pair format)
274 FALSE is a singleton */
276 static env_mail_type_t env_mail_type_list[] = {
277 { US"SIZE", ENV_MAIL_OPT_SIZE, TRUE },
278 { US"BODY", ENV_MAIL_OPT_BODY, TRUE },
279 { US"AUTH", ENV_MAIL_OPT_AUTH, TRUE },
281 { US"PRDR", ENV_MAIL_OPT_PRDR, FALSE },
283 { US"RET", ENV_MAIL_OPT_RET, TRUE },
284 { US"ENVID", ENV_MAIL_OPT_ENVID, TRUE },
286 { US"SMTPUTF8",ENV_MAIL_OPT_UTF8, FALSE }, /* rfc6531 */
288 /* keep this the last entry */
289 { US"NULL", ENV_MAIL_OPT_NULL, FALSE },
292 /* When reading SMTP from a remote host, we have to use our own versions of the
293 C input-reading functions, in order to be able to flush the SMTP output only
294 when about to read more data from the socket. This is the only way to get
295 optimal performance when the client is using pipelining. Flushing for every
296 command causes a separate packet and reply packet each time; saving all the
297 responses up (when pipelining) combines them into one packet and one response.
299 For simplicity, these functions are used for *all* SMTP input, not only when
300 receiving over a socket. However, after setting up a secure socket (SSL), input
301 is read via the OpenSSL library, and another set of functions is used instead
304 These functions are set in the receive_getc etc. variables and called with the
305 same interface as the C functions. However, since there can only ever be
306 one incoming SMTP call, we just use a single buffer and flags. There is no need
307 to implement a complicated private FILE-like structure.*/
309 static uschar *smtp_inbuffer;
310 static uschar *smtp_inptr;
311 static uschar *smtp_inend;
312 static int smtp_had_eof;
313 static int smtp_had_error;
316 /* forward declarations */
317 static int smtp_read_command(BOOL check_sync, unsigned buffer_lim);
318 static int synprot_error(int type, int code, uschar *data, uschar *errmess);
319 static void smtp_quit_handler(uschar **, uschar **);
320 static void smtp_rset_handler(void);
322 /*************************************************
323 * Recheck synchronization *
324 *************************************************/
326 /* Synchronization checks can never be perfect because a packet may be on its
327 way but not arrived when the check is done. Normally, the checks happen when
328 commands are read: Exim ensures that there is no more input in the input buffer.
329 In normal cases, the response to the command will be fast, and there is no
332 However, for some commands an ACL is run, and that can include delays. In those
333 cases, it is useful to do another check on the input just before sending the
334 response. This also applies at the start of a connection. This function does
335 that check by means of the select() function, as long as the facility is not
336 disabled or inappropriate. A failure of select() is ignored.
338 When there is unwanted input, we read it so that it appears in the log of the
342 Returns: TRUE if all is well; FALSE if there is input pending
346 wouldblock_reading(void)
350 struct timeval tzero = {.tv_sec = 0, .tv_usec = 0};
353 if (tls_in.active.sock >= 0)
354 return !tls_could_read();
357 if (smtp_inptr < smtp_inend)
360 fd = fileno(smtp_in);
363 rc = select(fd + 1, (SELECT_ARG2_TYPE *)&fds, NULL, NULL, &tzero);
365 if (rc <= 0) return TRUE; /* Not ready to read */
366 rc = smtp_getc(GETC_BUFFER_UNLIMITED);
367 if (rc < 0) return TRUE; /* End of file or error */
376 if (!smtp_enforce_sync || !sender_host_address || f.sender_host_notsocket)
379 return wouldblock_reading();
383 /* If there's input waiting (and we're doing pipelineing) then we can pipeline
384 a reponse with the one following. */
387 pipeline_response(void)
389 if ( !smtp_enforce_sync || !sender_host_address
390 || f.sender_host_notsocket || !f.smtp_in_pipelining_advertised)
393 if (wouldblock_reading()) return FALSE;
394 f.smtp_in_pipelining_used = TRUE;
399 #ifndef DISABLE_PIPE_CONNECT
401 pipeline_connect_sends(void)
403 if (!sender_host_address || f.sender_host_notsocket || !fl.pipe_connect_acceptable)
406 if (wouldblock_reading()) return FALSE;
407 f.smtp_in_early_pipe_used = TRUE;
412 /*************************************************
413 * Log incomplete transactions *
414 *************************************************/
416 /* This function is called after a transaction has been aborted by RSET, QUIT,
417 connection drops or other errors. It logs the envelope information received
418 so far in order to preserve address verification attempts.
420 Argument: string to indicate what aborted the transaction
425 incomplete_transaction_log(uschar *what)
427 if (!sender_address /* No transaction in progress */
428 || !LOGGING(smtp_incomplete_transaction))
431 /* Build list of recipients for logging */
433 if (recipients_count > 0)
435 raw_recipients = store_get(recipients_count * sizeof(uschar *), FALSE);
436 for (int i = 0; i < recipients_count; i++)
437 raw_recipients[i] = recipients_list[i].address;
438 raw_recipients_count = recipients_count;
441 log_write(L_smtp_incomplete_transaction, LOG_MAIN|LOG_SENDER|LOG_RECIPIENTS,
442 "%s incomplete transaction (%s)", host_and_ident(TRUE), what);
449 smtp_command_timeout_exit(void)
451 log_write(L_lost_incoming_connection,
452 LOG_MAIN, "SMTP command timeout on%s connection from %s",
453 tls_in.active.sock >= 0 ? " TLS" : "", host_and_ident(FALSE));
454 if (smtp_batched_input)
455 moan_smtp_batch(NULL, "421 SMTP command timeout"); /* Does not return */
456 smtp_notquit_exit(US"command-timeout", US"421",
457 US"%s: SMTP command timeout - closing connection",
458 smtp_active_hostname);
459 exim_exit(EXIT_FAILURE);
463 smtp_command_sigterm_exit(void)
465 log_write(0, LOG_MAIN, "%s closed after SIGTERM", smtp_get_connection_info());
466 if (smtp_batched_input)
467 moan_smtp_batch(NULL, "421 SIGTERM received"); /* Does not return */
468 smtp_notquit_exit(US"signal-exit", US"421",
469 US"%s: Service not available - closing connection", smtp_active_hostname);
470 exim_exit(EXIT_FAILURE);
474 smtp_data_timeout_exit(void)
476 log_write(L_lost_incoming_connection,
477 LOG_MAIN, "SMTP data timeout (message abandoned) on connection from %s F=<%s>",
478 sender_fullhost ? sender_fullhost : US"local process", sender_address);
479 receive_bomb_out(US"data-timeout", US"SMTP incoming data timeout");
480 /* Does not return */
484 smtp_data_sigint_exit(void)
486 log_write(0, LOG_MAIN, "%s closed after %s",
487 smtp_get_connection_info(), had_data_sigint == SIGTERM ? "SIGTERM":"SIGINT");
488 receive_bomb_out(US"signal-exit",
489 US"Service not available - SIGTERM or SIGINT received");
490 /* Does not return */
495 /* Refill the buffer, and notify DKIM verification code.
496 Return false for error or EOF.
500 smtp_refill(unsigned lim)
503 if (!smtp_out) return FALSE;
505 if (smtp_receive_timeout > 0) ALARM(smtp_receive_timeout);
507 /* Limit amount read, so non-message data is not fed to DKIM.
508 Take care to not touch the safety NUL at the end of the buffer. */
510 rc = read(fileno(smtp_in), smtp_inbuffer, MIN(IN_BUFFER_SIZE-1, lim));
512 if (smtp_receive_timeout > 0) ALARM_CLR(0);
515 /* Must put the error text in fixed store, because this might be during
516 header reading, where it releases unused store above the header. */
519 if (had_command_timeout) /* set by signal handler */
520 smtp_command_timeout_exit(); /* does not return */
521 if (had_command_sigterm)
522 smtp_command_sigterm_exit();
523 if (had_data_timeout)
524 smtp_data_timeout_exit();
526 smtp_data_sigint_exit();
528 smtp_had_error = save_errno;
529 smtp_read_error = string_copy_perm(
530 string_sprintf(" (error: %s)", strerror(save_errno)), FALSE);
537 dkim_exim_verify_feed(smtp_inbuffer, rc);
539 smtp_inend = smtp_inbuffer + rc;
540 smtp_inptr = smtp_inbuffer;
544 /*************************************************
545 * SMTP version of getc() *
546 *************************************************/
548 /* This gets the next byte from the SMTP input buffer. If the buffer is empty,
549 it flushes the output, and refills the buffer, with a timeout. The signal
550 handler is set appropriately by the calling function. This function is not used
551 after a connection has negotiated itself into an TLS/SSL state.
553 Arguments: lim Maximum amount to read/buffer
554 Returns: the next character or EOF
558 smtp_getc(unsigned lim)
560 if (smtp_inptr >= smtp_inend)
561 if (!smtp_refill(lim))
563 return *smtp_inptr++;
567 smtp_getbuf(unsigned * len)
572 if (smtp_inptr >= smtp_inend)
573 if (!smtp_refill(*len))
574 { *len = 0; return NULL; }
576 if ((size = smtp_inend - smtp_inptr) > *len) size = *len;
587 int n = smtp_inend - smtp_inptr;
588 if (chunking_state == CHUNKING_LAST && chunking_data_left < n)
589 n = chunking_data_left;
591 dkim_exim_verify_feed(smtp_inptr, n);
596 /* Forward declarations */
597 static inline void bdat_push_receive_functions(void);
598 static inline void bdat_pop_receive_functions(void);
601 /* Get a byte from the smtp input, in CHUNKING mode. Handle ack of the
602 previous BDAT chunk and getting new ones when we run out. Uses the
603 underlying smtp_getc or tls_getc both for that and for getting the
604 (buffered) data byte. EOD signals (an expected) no further data.
605 ERR signals a protocol error, and EOF a closed input stream.
607 Called from read_bdat_smtp() in receive.c for the message body, but also
608 by the headers read loop in receive_msg(); manipulates chunking_state
609 to handle the BDAT command/response.
610 Placed here due to the correlation with the above smtp_getc(), which it wraps,
611 and also by the need to do smtp command/response handling.
613 Arguments: lim (ignored)
614 Returns: the next character or ERR, EOD or EOF
618 bdat_getc(unsigned lim)
620 uschar * user_msg = NULL;
629 if (chunking_data_left > 0)
630 return lwr_receive_getc(chunking_data_left--);
632 bdat_pop_receive_functions();
634 dkim_save = dkim_collect_input;
635 dkim_collect_input = 0;
638 /* Unless PIPELINING was offered, there should be no next command
639 until after we ack that chunk */
641 if (!f.smtp_in_pipelining_advertised && !check_sync())
643 unsigned n = smtp_inend - smtp_inptr;
646 incomplete_transaction_log(US"sync failure");
647 log_write(0, LOG_MAIN|LOG_REJECT, "SMTP protocol synchronization error "
648 "(next input sent too soon: pipelining was not advertised): "
649 "rejected \"%s\" %s next input=\"%s\"%s",
650 smtp_cmd_buffer, host_and_ident(TRUE),
651 string_printing(string_copyn(smtp_inptr, n)),
652 smtp_inend - smtp_inptr > n ? "..." : "");
653 (void) synprot_error(L_smtp_protocol_error, 554, NULL,
654 US"SMTP synchronization error");
655 goto repeat_until_rset;
658 /* If not the last, ack the received chunk. The last response is delayed
659 until after the data ACL decides on it */
661 if (chunking_state == CHUNKING_LAST)
664 dkim_exim_verify_feed(NULL, 0); /* notify EOD */
669 smtp_printf("250 %u byte chunk received\r\n", FALSE, chunking_datasize);
670 chunking_state = CHUNKING_OFFERED;
671 DEBUG(D_receive) debug_printf("chunking state %d\n", (int)chunking_state);
673 /* Expect another BDAT cmd from input. RFC 3030 says nothing about
674 QUIT, RSET or NOOP but handling them seems obvious */
677 switch(smtp_read_command(TRUE, 1))
680 (void) synprot_error(L_smtp_protocol_error, 503, NULL,
681 US"only BDAT permissible after non-LAST BDAT");
684 switch(smtp_read_command(TRUE, 1))
686 case QUIT_CMD: smtp_quit_handler(&user_msg, &log_msg); /*FALLTHROUGH */
687 case EOF_CMD: return EOF;
688 case RSET_CMD: smtp_rset_handler(); return ERR;
689 default: if (synprot_error(L_smtp_protocol_error, 503, NULL,
690 US"only RSET accepted now") > 0)
692 goto repeat_until_rset;
696 smtp_quit_handler(&user_msg, &log_msg);
707 smtp_printf("250 OK\r\n", FALSE);
714 if (sscanf(CS smtp_cmd_data, "%u %n", &chunking_datasize, &n) < 1)
716 (void) synprot_error(L_smtp_protocol_error, 501, NULL,
717 US"missing size for BDAT command");
720 chunking_state = strcmpic(smtp_cmd_data+n, US"LAST") == 0
721 ? CHUNKING_LAST : CHUNKING_ACTIVE;
722 chunking_data_left = chunking_datasize;
723 DEBUG(D_receive) debug_printf("chunking state %d, %d bytes\n",
724 (int)chunking_state, chunking_data_left);
726 if (chunking_datasize == 0)
727 if (chunking_state == CHUNKING_LAST)
731 (void) synprot_error(L_smtp_protocol_error, 504, NULL,
732 US"zero size for BDAT command");
733 goto repeat_until_rset;
736 bdat_push_receive_functions();
738 dkim_collect_input = dkim_save;
740 break; /* to top of main loop */
747 bdat_getbuf(unsigned * len)
751 if (chunking_data_left <= 0)
752 { *len = 0; return NULL; }
754 if (*len > chunking_data_left) *len = chunking_data_left;
755 buf = lwr_receive_getbuf(len); /* Either smtp_getbuf or tls_getbuf */
756 chunking_data_left -= *len;
761 bdat_flush_data(void)
763 while (chunking_data_left)
765 unsigned n = chunking_data_left;
766 if (!bdat_getbuf(&n)) break;
769 bdat_pop_receive_functions();
771 if (chunking_state != CHUNKING_LAST)
773 chunking_state = CHUNKING_OFFERED;
774 DEBUG(D_receive) debug_printf("chunking state %d\n", (int)chunking_state);
780 bdat_push_receive_functions(void)
782 /* push the current receive_* function on the "stack", and
783 replace them by bdat_getc(), which in turn will use the lwr_receive_*
784 functions to do the dirty work. */
785 if (lwr_receive_getc == NULL)
787 lwr_receive_getc = receive_getc;
788 lwr_receive_getbuf = receive_getbuf;
789 lwr_receive_ungetc = receive_ungetc;
793 DEBUG(D_receive) debug_printf("chunking double-push receive functions\n");
796 receive_getc = bdat_getc;
797 receive_getbuf = bdat_getbuf;
798 receive_ungetc = bdat_ungetc;
802 bdat_pop_receive_functions(void)
804 if (lwr_receive_getc == NULL)
806 DEBUG(D_receive) debug_printf("chunking double-pop receive functions\n");
809 receive_getc = lwr_receive_getc;
810 receive_getbuf = lwr_receive_getbuf;
811 receive_ungetc = lwr_receive_ungetc;
813 lwr_receive_getc = NULL;
814 lwr_receive_getbuf = NULL;
815 lwr_receive_ungetc = NULL;
818 /*************************************************
819 * SMTP version of ungetc() *
820 *************************************************/
822 /* Puts a character back in the input buffer. Only ever
828 Returns: the character
834 if (smtp_inptr <= smtp_inbuffer)
835 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "buffer underflow in smtp_ungetc");
845 chunking_data_left++;
846 bdat_push_receive_functions(); /* we're not done yet, calling push is safe, because it checks the state before pushing anything */
847 return lwr_receive_ungetc(ch);
852 /*************************************************
853 * SMTP version of feof() *
854 *************************************************/
856 /* Tests for a previous EOF
859 Returns: non-zero if the eof flag is set
871 /*************************************************
872 * SMTP version of ferror() *
873 *************************************************/
875 /* Tests for a previous read error, and returns with errno
876 restored to what it was when the error was detected.
879 Returns: non-zero if the error flag is set
885 errno = smtp_had_error;
886 return smtp_had_error;
891 /*************************************************
892 * Test for characters in the SMTP buffer *
893 *************************************************/
895 /* Used at the end of a message
904 return smtp_inptr < smtp_inend;
909 /*************************************************
910 * Write formatted string to SMTP channel *
911 *************************************************/
913 /* This is a separate function so that we don't have to repeat everything for
914 TLS support or debugging. It is global so that the daemon and the
915 authentication functions can use it. It does not return any error indication,
916 because major problems such as dropped connections won't show up till an output
917 flush for non-TLS connections. The smtp_fflush() function is available for
918 checking that: for convenience, TLS output errors are remembered here so that
919 they are also picked up later by smtp_fflush().
921 This function is exposed to the local_scan API; do not change the signature.
925 more further data expected
926 ... optional arguments
932 smtp_printf(const char *format, BOOL more, ...)
937 smtp_vprintf(format, more, ap);
941 /* This is split off so that verify.c:respond_printf() can, in effect, call
942 smtp_printf(), bearing in mind that in C a vararg function can't directly
943 call another vararg function, only a function which accepts a va_list.
945 This function is exposed to the local_scan API; do not change the signature.
947 /*XXX consider passing caller-info in, for string_vformat-onward */
950 smtp_vprintf(const char *format, BOOL more, va_list ap)
952 gstring gs = { .size = big_buffer_size, .ptr = 0, .s = big_buffer };
955 /* Use taint-unchecked routines for writing into big_buffer, trusting
956 that we'll never expand it. */
958 yield = !! string_vformat(&gs, SVFMT_TAINT_NOCHK, format, ap);
959 string_from_gstring(&gs);
963 uschar *msg_copy, *cr, *end;
964 msg_copy = string_copy(gs.s);
965 end = msg_copy + gs.ptr;
966 while ((cr = Ustrchr(msg_copy, '\r')) != NULL) /* lose CRs */
967 memmove(cr, cr + 1, (end--) - cr);
968 debug_printf("SMTP>> %s", msg_copy);
973 log_write(0, LOG_MAIN|LOG_PANIC, "string too large in smtp_printf()");
974 smtp_closedown(US"Unexpected error");
975 exim_exit(EXIT_FAILURE);
978 /* If this is the first output for a (non-batch) RCPT command, see if all RCPTs
979 have had the same. Note: this code is also present in smtp_respond(). It would
980 be tidier to have it only in one place, but when it was added, it was easier to
981 do it that way, so as not to have to mess with the code for the RCPT command,
982 which sometimes uses smtp_printf() and sometimes smtp_respond(). */
984 if (fl.rcpt_in_progress)
986 if (rcpt_smtp_response == NULL)
987 rcpt_smtp_response = string_copy(big_buffer);
988 else if (fl.rcpt_smtp_response_same &&
989 Ustrcmp(rcpt_smtp_response, big_buffer) != 0)
990 fl.rcpt_smtp_response_same = FALSE;
991 fl.rcpt_in_progress = FALSE;
994 /* Now write the string */
998 tls_in.active.sock >= 0 ? (tls_write(NULL, gs.s, gs.ptr, more) < 0) :
1000 (fwrite(gs.s, gs.ptr, 1, smtp_out) == 0)
1002 smtp_write_error = -1;
1007 /*************************************************
1008 * Flush SMTP out and check for error *
1009 *************************************************/
1011 /* This function isn't currently used within Exim (it detects errors when it
1012 tries to read the next SMTP input), but is available for use in local_scan().
1013 It flushes the output and checks for errors.
1016 Returns: 0 for no error; -1 after an error
1022 if (tls_in.active.sock < 0 && fflush(smtp_out) != 0) smtp_write_error = -1;
1026 tls_in.active.sock >= 0 ? (tls_write(NULL, NULL, 0, FALSE) < 0) :
1028 (fflush(smtp_out) != 0)
1030 smtp_write_error = -1;
1032 return smtp_write_error;
1037 /*************************************************
1038 * SMTP command read timeout *
1039 *************************************************/
1041 /* Signal handler for timing out incoming SMTP commands. This attempts to
1044 Argument: signal number (SIGALRM)
1049 command_timeout_handler(int sig)
1051 had_command_timeout = sig;
1056 /*************************************************
1057 * SIGTERM received *
1058 *************************************************/
1060 /* Signal handler for handling SIGTERM. Again, try to finish tidily.
1062 Argument: signal number (SIGTERM)
1067 command_sigterm_handler(int sig)
1069 had_command_sigterm = sig;
1075 #ifdef SUPPORT_PROXY
1076 /*************************************************
1077 * Check if host is required proxy host *
1078 *************************************************/
1079 /* The function determines if inbound host will be a regular smtp host
1080 or if it is configured that it must use Proxy Protocol. A local
1088 check_proxy_protocol_host()
1092 if ( sender_host_address
1093 && (rc = verify_check_this_host(CUSS &hosts_proxy, NULL, NULL,
1094 sender_host_address, NULL)) == OK)
1097 debug_printf("Detected proxy protocol configured host\n");
1098 proxy_session = TRUE;
1100 return proxy_session;
1104 /*************************************************
1105 * Read data until newline or end of buffer *
1106 *************************************************/
1107 /* While SMTP is server-speaks-first, TLS is client-speaks-first, so we can't
1108 read an entire buffer and assume there will be nothing past a proxy protocol
1109 header. Our approach normally is to use stdio, but again that relies upon
1110 "STARTTLS\r\n" and a server response before the client starts TLS handshake, or
1111 reading _nothing_ before client TLS handshake. So we don't want to use the
1112 usual buffering reads which may read enough to block TLS starting.
1114 So unfortunately we're down to "read one byte at a time, with a syscall each,
1115 and expect a little overhead", for all proxy-opened connections which are v1,
1116 just to handle the TLS-on-connect case. Since SSL functions wrap the
1117 underlying fd, we can't assume that we can feed them any already-read content.
1119 We need to know where to read to, the max capacity, and we'll read until we
1120 get a CR and one more character. Let the caller scream if it's CR+!LF.
1122 Return the amount read.
1126 swallow_until_crlf(int fd, uschar *base, int already, int capacity)
1128 uschar *to = base + already;
1134 /* For "PROXY UNKNOWN\r\n" we, at time of writing, expect to have read
1135 up through the \r; for the _normal_ case, we haven't yet seen the \r. */
1137 cr = memchr(base, '\r', already);
1140 if ((cr - base) < already - 1)
1142 /* \r and presumed \n already within what we have; probably not
1143 actually proxy protocol, but abort cleanly. */
1146 /* \r is last character read, just need one more. */
1150 while (capacity > 0)
1152 do { ret = read(fd, to, 1); } while (ret == -1 && errno == EINTR && !had_command_timeout);
1164 /* reached end without having room for a final newline, abort */
1169 /*************************************************
1170 * Setup host for proxy protocol *
1171 *************************************************/
1172 /* The function configures the connection based on a header from the
1173 inbound host to use Proxy Protocol. The specification is very exact
1174 so exit with an error if do not find the exact required pieces. This
1175 includes an incorrect number of spaces separating args.
1178 Returns: Boolean success
1182 setup_proxy_protocol_host()
1194 struct { /* TCP/UDP over IPv4, len = 12 */
1200 struct { /* TCP/UDP over IPv6, len = 36 */
1201 uint8_t src_addr[16];
1202 uint8_t dst_addr[16];
1206 struct { /* AF_UNIX sockets, len = 216 */
1207 uschar src_addr[108];
1208 uschar dst_addr[108];
1214 /* Temp variables used in PPv2 address:port parsing */
1216 char tmpip[INET_ADDRSTRLEN];
1217 struct sockaddr_in tmpaddr;
1218 char tmpip6[INET6_ADDRSTRLEN];
1219 struct sockaddr_in6 tmpaddr6;
1221 /* We can't read "all data until end" because while SMTP is
1222 server-speaks-first, the TLS handshake is client-speaks-first, so for
1223 TLS-on-connect ports the proxy protocol header will usually be immediately
1224 followed by a TLS handshake, and with N TLS libraries, we can't reliably
1225 reinject data for reading by those. So instead we first read "enough to be
1226 safely read within the header, and figure out how much more to read".
1227 For v1 we will later read to the end-of-line, for v2 we will read based upon
1230 The v2 sig is 12 octets, and another 4 gets us the length, so we know how much
1231 data is needed total. For v1, where the line looks like:
1232 PROXY TCPn L3src L3dest SrcPort DestPort \r\n
1234 However, for v1 there's also `PROXY UNKNOWN\r\n` which is only 15 octets.
1235 We seem to support that. So, if we read 14 octets then we can tell if we're
1236 v2 or v1. If we're v1, we can continue reading as normal.
1238 If we're v2, we can't slurp up the entire header. We need the length in the
1239 15th & 16th octets, then to read everything after that.
1241 So to safely handle v1 and v2, with client-sent-first supported correctly,
1242 we have to do a minimum of 3 read calls, not 1. Eww.
1245 #define PROXY_INITIAL_READ 14
1246 #define PROXY_V2_HEADER_SIZE 16
1247 #if PROXY_INITIAL_READ > PROXY_V2_HEADER_SIZE
1248 # error Code bug in sizes of data to read for proxy usage
1253 int fd = fileno(smtp_in);
1254 const char v2sig[12] = "\x0D\x0A\x0D\x0A\x00\x0D\x0A\x51\x55\x49\x54\x0A";
1255 uschar * iptype; /* To display debug info */
1256 socklen_t vslen = sizeof(struct timeval);
1259 os_non_restarting_signal(SIGALRM, command_timeout_handler);
1260 ALARM(proxy_protocol_timeout);
1264 /* The inbound host was declared to be a Proxy Protocol host, so
1265 don't do a PEEK into the data, actually slurp up enough to be
1266 "safe". Can't take it all because TLS-on-connect clients follow
1267 immediately with TLS handshake. */
1268 ret = read(fd, &hdr, PROXY_INITIAL_READ);
1270 while (ret == -1 && errno == EINTR && !had_command_timeout);
1275 /* For v2, handle reading the length, and then the rest. */
1276 if ((ret == PROXY_INITIAL_READ) && (memcmp(&hdr.v2, v2sig, sizeof(v2sig)) == 0))
1281 /* First get the length fields. */
1284 retmore = read(fd, (uschar*)&hdr + ret, PROXY_V2_HEADER_SIZE - PROXY_INITIAL_READ);
1285 } while (retmore == -1 && errno == EINTR && !had_command_timeout);
1290 ver = (hdr.v2.ver_cmd & 0xf0) >> 4;
1292 /* May 2014: haproxy combined the version and command into one byte to
1293 allow two full bytes for the length field in order to proxy SSL
1294 connections. SSL Proxy is not supported in this version of Exim, but
1295 must still separate values here. */
1299 DEBUG(D_receive) debug_printf("Invalid Proxy Protocol version: %d\n", ver);
1303 /* The v2 header will always be 16 bytes per the spec. */
1304 size = 16 + ntohs(hdr.v2.len);
1305 DEBUG(D_receive) debug_printf("Detected PROXYv2 header, size %d (limit %d)\n",
1306 size, (int)sizeof(hdr));
1308 /* We should now have 16 octets (PROXY_V2_HEADER_SIZE), and we know the total
1309 amount that we need. Double-check that the size is not unreasonable, then
1311 if (size > sizeof(hdr))
1313 DEBUG(D_receive) debug_printf("PROXYv2 header size unreasonably large; security attack?\n");
1321 retmore = read(fd, (uschar*)&hdr + ret, size-ret);
1322 } while (retmore == -1 && errno == EINTR && !had_command_timeout);
1326 DEBUG(D_receive) debug_printf("PROXYv2: have %d/%d required octets\n", ret, size);
1327 } while (ret < size);
1329 } /* end scope for getting rest of data for v2 */
1331 /* At this point: if PROXYv2, we've read the exact size required for all data;
1332 if PROXYv1 then we've read "less than required for any valid line" and should
1335 if (ret >= 16 && memcmp(&hdr.v2, v2sig, 12) == 0)
1337 uint8_t cmd = (hdr.v2.ver_cmd & 0x0f);
1341 case 0x01: /* PROXY command */
1344 case 0x11: /* TCPv4 address type */
1346 tmpaddr.sin_addr.s_addr = hdr.v2.addr.ip4.src_addr;
1347 inet_ntop(AF_INET, &tmpaddr.sin_addr, CS &tmpip, sizeof(tmpip));
1348 if (!string_is_ip_address(US tmpip, NULL))
1350 DEBUG(D_receive) debug_printf("Invalid %s source IP\n", iptype);
1353 proxy_local_address = sender_host_address;
1354 sender_host_address = string_copy(US tmpip);
1355 tmpport = ntohs(hdr.v2.addr.ip4.src_port);
1356 proxy_local_port = sender_host_port;
1357 sender_host_port = tmpport;
1358 /* Save dest ip/port */
1359 tmpaddr.sin_addr.s_addr = hdr.v2.addr.ip4.dst_addr;
1360 inet_ntop(AF_INET, &tmpaddr.sin_addr, CS &tmpip, sizeof(tmpip));
1361 if (!string_is_ip_address(US tmpip, NULL))
1363 DEBUG(D_receive) debug_printf("Invalid %s dest port\n", iptype);
1366 proxy_external_address = string_copy(US tmpip);
1367 tmpport = ntohs(hdr.v2.addr.ip4.dst_port);
1368 proxy_external_port = tmpport;
1370 case 0x21: /* TCPv6 address type */
1372 memmove(tmpaddr6.sin6_addr.s6_addr, hdr.v2.addr.ip6.src_addr, 16);
1373 inet_ntop(AF_INET6, &tmpaddr6.sin6_addr, CS &tmpip6, sizeof(tmpip6));
1374 if (!string_is_ip_address(US tmpip6, NULL))
1376 DEBUG(D_receive) debug_printf("Invalid %s source IP\n", iptype);
1379 proxy_local_address = sender_host_address;
1380 sender_host_address = string_copy(US tmpip6);
1381 tmpport = ntohs(hdr.v2.addr.ip6.src_port);
1382 proxy_local_port = sender_host_port;
1383 sender_host_port = tmpport;
1384 /* Save dest ip/port */
1385 memmove(tmpaddr6.sin6_addr.s6_addr, hdr.v2.addr.ip6.dst_addr, 16);
1386 inet_ntop(AF_INET6, &tmpaddr6.sin6_addr, CS &tmpip6, sizeof(tmpip6));
1387 if (!string_is_ip_address(US tmpip6, NULL))
1389 DEBUG(D_receive) debug_printf("Invalid %s dest port\n", iptype);
1392 proxy_external_address = string_copy(US tmpip6);
1393 tmpport = ntohs(hdr.v2.addr.ip6.dst_port);
1394 proxy_external_port = tmpport;
1398 debug_printf("Unsupported PROXYv2 connection type: 0x%02x\n",
1402 /* Unsupported protocol, keep local connection address */
1404 case 0x00: /* LOCAL command */
1405 /* Keep local connection address for LOCAL */
1410 debug_printf("Unsupported PROXYv2 command: 0x%x\n", cmd);
1414 else if (ret >= 8 && memcmp(hdr.v1.line, "PROXY", 5) == 0)
1418 uschar *sp; /* Utility variables follow */
1423 /* get the rest of the line */
1424 r2 = swallow_until_crlf(fd, (uschar*)&hdr, ret, sizeof(hdr)-ret);
1429 p = string_copy(hdr.v1.line);
1430 end = memchr(p, '\r', ret - 1);
1432 if (!end || (end == (uschar*)&hdr + ret) || end[1] != '\n')
1434 DEBUG(D_receive) debug_printf("Partial or invalid PROXY header\n");
1437 *end = '\0'; /* Terminate the string */
1438 size = end + 2 - p; /* Skip header + CRLF */
1439 DEBUG(D_receive) debug_printf("Detected PROXYv1 header\n");
1440 DEBUG(D_receive) debug_printf("Bytes read not within PROXY header: %d\n", ret - size);
1441 /* Step through the string looking for the required fields. Ensure
1442 strict adherence to required formatting, exit for any error. */
1444 if (!isspace(*(p++)))
1446 DEBUG(D_receive) debug_printf("Missing space after PROXY command\n");
1449 if (!Ustrncmp(p, CCS"TCP4", 4))
1451 else if (!Ustrncmp(p,CCS"TCP6", 4))
1453 else if (!Ustrncmp(p,CCS"UNKNOWN", 7))
1455 iptype = US"Unknown";
1460 DEBUG(D_receive) debug_printf("Invalid TCP type\n");
1464 p += Ustrlen(iptype);
1465 if (!isspace(*(p++)))
1467 DEBUG(D_receive) debug_printf("Missing space after TCP4/6 command\n");
1470 /* Find the end of the arg */
1471 if ((sp = Ustrchr(p, ' ')) == NULL)
1474 debug_printf("Did not find proxied src %s\n", iptype);
1478 if(!string_is_ip_address(p, NULL))
1481 debug_printf("Proxied src arg is not an %s address\n", iptype);
1484 proxy_local_address = sender_host_address;
1485 sender_host_address = p;
1487 if ((sp = Ustrchr(p, ' ')) == NULL)
1490 debug_printf("Did not find proxy dest %s\n", iptype);
1494 if(!string_is_ip_address(p, NULL))
1497 debug_printf("Proxy dest arg is not an %s address\n", iptype);
1500 proxy_external_address = p;
1502 if ((sp = Ustrchr(p, ' ')) == NULL)
1504 DEBUG(D_receive) debug_printf("Did not find proxied src port\n");
1508 tmp_port = strtol(CCS p, &endc, 10);
1509 if (*endc || tmp_port == 0)
1512 debug_printf("Proxied src port '%s' not an integer\n", p);
1515 proxy_local_port = sender_host_port;
1516 sender_host_port = tmp_port;
1518 if ((sp = Ustrchr(p, '\0')) == NULL)
1520 DEBUG(D_receive) debug_printf("Did not find proxy dest port\n");
1523 tmp_port = strtol(CCS p, &endc, 10);
1524 if (*endc || tmp_port == 0)
1527 debug_printf("Proxy dest port '%s' not an integer\n", p);
1530 proxy_external_port = tmp_port;
1531 /* Already checked for /r /n above. Good V1 header received. */
1535 /* Wrong protocol */
1536 DEBUG(D_receive) debug_printf("Invalid proxy protocol version negotiation\n");
1537 (void) swallow_until_crlf(fd, (uschar*)&hdr, ret, sizeof(hdr)-ret);
1543 debug_printf("Valid %s sender from Proxy Protocol header\n", iptype);
1544 yield = proxy_session;
1546 /* Don't flush any potential buffer contents. Any input on proxyfail
1547 should cause a synchronization failure */
1550 DEBUG(D_receive) if (had_command_timeout)
1551 debug_printf("Timeout while reading proxy header\n");
1556 sender_host_name = NULL;
1557 (void) host_name_lookup();
1558 host_build_sender_fullhost();
1562 f.proxy_session_failed = TRUE;
1564 debug_printf("Failure to extract proxied host, only QUIT allowed\n");
1572 /*************************************************
1573 * Read one command line *
1574 *************************************************/
1576 /* Strictly, SMTP commands coming over the net are supposed to end with CRLF.
1577 There are sites that don't do this, and in any case internal SMTP probably
1578 should check only for LF. Consequently, we check here for LF only. The line
1579 ends up with [CR]LF removed from its end. If we get an overlong line, treat as
1580 an unknown command. The command is read into the global smtp_cmd_buffer so that
1581 it is available via $smtp_command.
1583 The character reading routine sets up a timeout for each block actually read
1584 from the input (which may contain more than one command). We set up a special
1585 signal handler that closes down the session on a timeout. Control does not
1586 return when it runs.
1589 check_sync if TRUE, check synchronization rules if global option is TRUE
1590 buffer_lim maximum to buffer in lower layer
1592 Returns: a code identifying the command (enumerated above)
1596 smtp_read_command(BOOL check_sync, unsigned buffer_lim)
1600 BOOL hadnull = FALSE;
1602 had_command_timeout = 0;
1603 os_non_restarting_signal(SIGALRM, command_timeout_handler);
1605 while ((c = (receive_getc)(buffer_lim)) != '\n' && c != EOF)
1607 if (ptr >= SMTP_CMD_BUFFER_SIZE)
1609 os_non_restarting_signal(SIGALRM, sigalrm_handler);
1617 smtp_cmd_buffer[ptr++] = c;
1620 receive_linecount++; /* For BSMTP errors */
1621 os_non_restarting_signal(SIGALRM, sigalrm_handler);
1623 /* If hit end of file, return pseudo EOF command. Whether we have a
1624 part-line already read doesn't matter, since this is an error state. */
1626 if (c == EOF) return EOF_CMD;
1628 /* Remove any CR and white space at the end of the line, and terminate the
1631 while (ptr > 0 && isspace(smtp_cmd_buffer[ptr-1])) ptr--;
1632 smtp_cmd_buffer[ptr] = 0;
1634 DEBUG(D_receive) debug_printf("SMTP<< %s\n", smtp_cmd_buffer);
1636 /* NULLs are not allowed in SMTP commands */
1638 if (hadnull) return BADCHAR_CMD;
1640 /* Scan command list and return identity, having set the data pointer
1641 to the start of the actual data characters. Check for SMTP synchronization
1644 for (smtp_cmd_list * p = cmd_list; p < cmd_list_end; p++)
1646 #ifdef SUPPORT_PROXY
1647 /* Only allow QUIT command if Proxy Protocol parsing failed */
1648 if (proxy_session && f.proxy_session_failed && p->cmd != QUIT_CMD)
1652 && strncmpic(smtp_cmd_buffer, US p->name, p->len) == 0
1653 && ( smtp_cmd_buffer[p->len-1] == ':' /* "mail from:" or "rcpt to:" */
1654 || smtp_cmd_buffer[p->len] == 0
1655 || smtp_cmd_buffer[p->len] == ' '
1658 if (smtp_inptr < smtp_inend && /* Outstanding input */
1659 p->cmd < sync_cmd_limit && /* Command should sync */
1660 check_sync && /* Local flag set */
1661 smtp_enforce_sync && /* Global flag set */
1662 sender_host_address != NULL && /* Not local input */
1663 !f.sender_host_notsocket) /* Really is a socket */
1666 /* The variables $smtp_command and $smtp_command_argument point into the
1667 unmodified input buffer. A copy of the latter is taken for actual
1668 processing, so that it can be chopped up into separate parts if necessary,
1669 for example, when processing a MAIL command options such as SIZE that can
1670 follow the sender address. */
1672 smtp_cmd_argument = smtp_cmd_buffer + p->len;
1673 while (isspace(*smtp_cmd_argument)) smtp_cmd_argument++;
1674 Ustrcpy(smtp_data_buffer, smtp_cmd_argument);
1675 smtp_cmd_data = smtp_data_buffer;
1677 /* Count non-mail commands from those hosts that are controlled in this
1678 way. The default is all hosts. We don't waste effort checking the list
1679 until we get a non-mail command, but then cache the result to save checking
1680 again. If there's a DEFER while checking the host, assume it's in the list.
1682 Note that one instance of RSET, EHLO/HELO, and STARTTLS is allowed at the
1683 start of each incoming message by fiddling with the value in the table. */
1685 if (!p->is_mail_cmd)
1687 if (count_nonmail == TRUE_UNSET) count_nonmail =
1688 verify_check_host(&smtp_accept_max_nonmail_hosts) != FAIL;
1689 if (count_nonmail && ++nonmail_command_count > smtp_accept_max_nonmail)
1690 return TOO_MANY_NONMAIL_CMD;
1693 /* If there is data for a command that does not expect it, generate the
1696 return (p->has_arg || *smtp_cmd_data == 0)? p->cmd : BADARG_CMD;
1700 #ifdef SUPPORT_PROXY
1701 /* Only allow QUIT command if Proxy Protocol parsing failed */
1702 if (proxy_session && f.proxy_session_failed)
1703 return PROXY_FAIL_IGNORE_CMD;
1706 /* Enforce synchronization for unknown commands */
1708 if ( smtp_inptr < smtp_inend /* Outstanding input */
1709 && check_sync /* Local flag set */
1710 && smtp_enforce_sync /* Global flag set */
1711 && sender_host_address /* Not local input */
1712 && !f.sender_host_notsocket) /* Really is a socket */
1720 /*************************************************
1721 * Forced closedown of call *
1722 *************************************************/
1724 /* This function is called from log.c when Exim is dying because of a serious
1725 disaster, and also from some other places. If an incoming non-batched SMTP
1726 channel is open, it swallows the rest of the incoming message if in the DATA
1727 phase, sends the reply string, and gives an error to all subsequent commands
1728 except QUIT. The existence of an SMTP call is detected by the non-NULLness of
1732 message SMTP reply string to send, excluding the code
1738 smtp_closedown(uschar *message)
1740 if (!smtp_in || smtp_batched_input) return;
1741 receive_swallow_smtp();
1742 smtp_printf("421 %s\r\n", FALSE, message);
1744 for (;;) switch(smtp_read_command(FALSE, GETC_BUFFER_UNLIMITED))
1750 f.smtp_in_quit = TRUE;
1751 smtp_printf("221 %s closing connection\r\n", FALSE, smtp_active_hostname);
1756 smtp_printf("250 Reset OK\r\n", FALSE);
1760 smtp_printf("421 %s\r\n", FALSE, message);
1768 /*************************************************
1769 * Set up connection info for logging *
1770 *************************************************/
1772 /* This function is called when logging information about an SMTP connection.
1773 It sets up appropriate source information, depending on the type of connection.
1774 If sender_fullhost is NULL, we are at a very early stage of the connection;
1775 just use the IP address.
1778 Returns: a string describing the connection
1782 smtp_get_connection_info(void)
1784 const uschar * hostname = sender_fullhost
1785 ? sender_fullhost : sender_host_address;
1788 return string_sprintf("SMTP connection from %s", hostname);
1790 if (f.sender_host_unknown || f.sender_host_notsocket)
1791 return string_sprintf("SMTP connection from %s", sender_ident);
1794 return string_sprintf("SMTP connection from %s (via inetd)", hostname);
1796 if (LOGGING(incoming_interface) && interface_address)
1797 return string_sprintf("SMTP connection from %s I=[%s]:%d", hostname,
1798 interface_address, interface_port);
1800 return string_sprintf("SMTP connection from %s", hostname);
1806 /* Append TLS-related information to a log line
1809 g String under construction: allocated string to extend, or NULL
1811 Returns: Allocated string or NULL
1814 s_tlslog(gstring * g)
1816 if (LOGGING(tls_cipher) && tls_in.cipher)
1818 g = string_append(g, 2, US" X=", tls_in.cipher);
1819 #ifndef DISABLE_TLS_RESUME
1820 if (LOGGING(tls_resumption) && tls_in.resumption & RESUME_USED)
1821 g = string_catn(g, US"*", 1);
1824 if (LOGGING(tls_certificate_verified) && tls_in.cipher)
1825 g = string_append(g, 2, US" CV=", tls_in.certificate_verified? "yes":"no");
1826 if (LOGGING(tls_peerdn) && tls_in.peerdn)
1827 g = string_append(g, 3, US" DN=\"", string_printing(tls_in.peerdn), US"\"");
1828 if (LOGGING(tls_sni) && tls_in.sni)
1829 g = string_append(g, 2, US" SNI=", string_printing2(tls_in.sni, SP_TAB|SP_SPACE));
1837 s_connhad_log(gstring * g)
1839 const uschar * sep = smtp_connection_had[SMTP_HBUFF_SIZE-1] != SCH_NONE
1840 ? US" C=..." : US" C=";
1842 for (int i = smtp_ch_index; i < SMTP_HBUFF_SIZE; i++)
1843 if (smtp_connection_had[i] != SCH_NONE)
1845 g = string_append(g, 2, sep, smtp_names[smtp_connection_had[i]]);
1848 for (int i = 0; i < smtp_ch_index; i++, sep = US",")
1849 g = string_append(g, 2, sep, smtp_names[smtp_connection_had[i]]);
1854 /*************************************************
1855 * Log lack of MAIL if so configured *
1856 *************************************************/
1858 /* This function is called when an SMTP session ends. If the log selector
1859 smtp_no_mail is set, write a log line giving some details of what has happened
1860 in the SMTP session.
1867 smtp_log_no_mail(void)
1872 if (smtp_mailcmd_count > 0 || !LOGGING(smtp_no_mail))
1875 if (sender_host_authenticated)
1877 g = string_append(g, 2, US" A=", sender_host_authenticated);
1878 if (authenticated_id) g = string_append(g, 2, US":", authenticated_id);
1885 g = s_connhad_log(g);
1887 if (!(s = string_from_gstring(g))) s = US"";
1889 log_write(0, LOG_MAIN, "no MAIL in %sSMTP connection from %s D=%s%s",
1890 f.tcp_in_fastopen ? f.tcp_in_fastopen_data ? US"TFO* " : US"TFO " : US"",
1891 host_and_ident(FALSE), string_timesince(&smtp_connection_start), s);
1895 /* Return list of recent smtp commands */
1900 gstring * list = NULL;
1903 for (int i = smtp_ch_index; i < SMTP_HBUFF_SIZE; i++)
1904 if (smtp_connection_had[i] != SCH_NONE)
1905 list = string_append_listele(list, ',', smtp_names[smtp_connection_had[i]]);
1907 for (int i = 0; i < smtp_ch_index; i++)
1908 list = string_append_listele(list, ',', smtp_names[smtp_connection_had[i]]);
1910 s = string_from_gstring(list);
1911 return s ? s : US"";
1917 /*************************************************
1918 * Check HELO line and set sender_helo_name *
1919 *************************************************/
1921 /* Check the format of a HELO line. The data for HELO/EHLO is supposed to be
1922 the domain name of the sending host, or an ip literal in square brackets. The
1923 argument is placed in sender_helo_name, which is in malloc store, because it
1924 must persist over multiple incoming messages. If helo_accept_junk is set, this
1925 host is permitted to send any old junk (needed for some broken hosts).
1926 Otherwise, helo_allow_chars can be used for rogue characters in general
1927 (typically people want to let in underscores).
1930 s the data portion of the line (already past any white space)
1932 Returns: TRUE or FALSE
1936 check_helo(uschar *s)
1939 uschar *end = s + Ustrlen(s);
1940 BOOL yield = fl.helo_accept_junk;
1942 /* Discard any previous helo name */
1944 sender_helo_name = NULL;
1946 /* Skip tests if junk is permitted. */
1950 /* Allow the new standard form for IPv6 address literals, namely,
1951 [IPv6:....], and because someone is bound to use it, allow an equivalent
1952 IPv4 form. Allow plain addresses as well. */
1959 if (strncmpic(s, US"[IPv6:", 6) == 0)
1960 yield = (string_is_ip_address(s+6, NULL) == 6);
1961 else if (strncmpic(s, US"[IPv4:", 6) == 0)
1962 yield = (string_is_ip_address(s+6, NULL) == 4);
1964 yield = (string_is_ip_address(s+1, NULL) != 0);
1969 /* Non-literals must be alpha, dot, hyphen, plus any non-valid chars
1970 that have been configured (usually underscore - sigh). */
1973 for (yield = TRUE; *s; s++)
1974 if (!isalnum(*s) && *s != '.' && *s != '-' &&
1975 Ustrchr(helo_allow_chars, *s) == NULL)
1981 /* Save argument if OK */
1983 if (yield) sender_helo_name = string_copy_perm(start, TRUE);
1991 /*************************************************
1992 * Extract SMTP command option *
1993 *************************************************/
1995 /* This function picks the next option setting off the end of smtp_cmd_data. It
1996 is called for MAIL FROM and RCPT TO commands, to pick off the optional ESMTP
1997 things that can appear there.
2000 name point this at the name
2001 value point this at the data string
2003 Returns: TRUE if found an option
2007 extract_option(uschar **name, uschar **value)
2011 if (Ustrlen(smtp_cmd_data) <= 0) return FALSE;
2012 v = smtp_cmd_data + Ustrlen(smtp_cmd_data) - 1;
2013 while (v > smtp_cmd_data && isspace(*v)) v--;
2016 while (v > smtp_cmd_data && *v != '=' && !isspace(*v))
2018 /* Take care to not stop at a space embedded in a quoted local-part */
2021 do v--; while (v > smtp_cmd_data && *v != '"');
2022 if (v <= smtp_cmd_data) return FALSE;
2026 if (v <= smtp_cmd_data) return FALSE;
2031 while (n > smtp_cmd_data && isalpha(n[-1])) n--;
2032 /* RFC says SP, but TAB seen in wild and other major MTAs accept it */
2033 if (n <= smtp_cmd_data || !isspace(n[-1])) return FALSE;
2050 /*************************************************
2051 * Reset for new message *
2052 *************************************************/
2054 /* This function is called whenever the SMTP session is reset from
2055 within either of the setup functions; also from the daemon loop.
2057 Argument: the stacking pool storage reset point
2062 smtp_reset(void *reset_point)
2064 recipients_list = NULL;
2065 rcpt_count = rcpt_defer_count = rcpt_fail_count =
2066 raw_recipients_count = recipients_count = recipients_list_max = 0;
2067 message_linecount = 0;
2069 message_body = message_body_end = NULL;
2070 acl_added_headers = NULL;
2071 acl_removed_headers = NULL;
2072 f.queue_only_policy = FALSE;
2073 rcpt_smtp_response = NULL;
2074 fl.rcpt_smtp_response_same = TRUE;
2075 fl.rcpt_in_progress = FALSE;
2076 f.deliver_freeze = FALSE; /* Can be set by ACL */
2077 freeze_tell = freeze_tell_config; /* Can be set by ACL */
2078 fake_response = OK; /* Can be set by ACL */
2079 #ifdef WITH_CONTENT_SCAN
2080 f.no_mbox_unspool = FALSE; /* Can be set by ACL */
2082 f.submission_mode = FALSE; /* Can be set by ACL */
2083 f.suppress_local_fixups = f.suppress_local_fixups_default; /* Can be set by ACL */
2084 f.active_local_from_check = local_from_check; /* Can be set by ACL */
2085 f.active_local_sender_retain = local_sender_retain; /* Can be set by ACL */
2086 sending_ip_address = NULL;
2087 return_path = sender_address = NULL;
2088 deliver_localpart_data = deliver_domain_data =
2089 recipient_data = sender_data = NULL; /* Can be set by ACL */
2090 recipient_verify_failure = NULL;
2091 deliver_localpart_parent = deliver_localpart_orig = NULL;
2092 deliver_domain_parent = deliver_domain_orig = NULL;
2093 callout_address = NULL;
2094 submission_name = NULL; /* Can be set by ACL */
2095 raw_sender = NULL; /* After SMTP rewrite, before qualifying */
2096 sender_address_unrewritten = NULL; /* Set only after verify rewrite */
2097 sender_verified_list = NULL; /* No senders verified */
2098 memset(sender_address_cache, 0, sizeof(sender_address_cache));
2099 memset(sender_domain_cache, 0, sizeof(sender_domain_cache));
2101 authenticated_sender = NULL;
2102 #ifdef EXPERIMENTAL_BRIGHTMAIL
2104 bmi_verdicts = NULL;
2106 dnslist_domain = dnslist_matched = NULL;
2108 spf_header_comment = spf_received = spf_result = spf_smtp_comment = NULL;
2109 spf_result_guessed = FALSE;
2111 #ifndef DISABLE_DKIM
2112 dkim_cur_signer = dkim_signers =
2113 dkim_signing_domain = dkim_signing_selector = dkim_signatures = NULL;
2114 dkim_cur_signer = dkim_signers = dkim_signing_domain = dkim_signing_selector = NULL;
2115 f.dkim_disable_verify = FALSE;
2116 dkim_collect_input = 0;
2117 dkim_verify_overall = dkim_verify_status = dkim_verify_reason = NULL;
2118 dkim_key_length = 0;
2120 #ifdef SUPPORT_DMARC
2121 f.dmarc_has_been_checked = f.dmarc_disable_verify = f.dmarc_enable_forensic = FALSE;
2122 dmarc_domain_policy = dmarc_status = dmarc_status_text =
2123 dmarc_used_domain = NULL;
2125 #ifdef EXPERIMENTAL_ARC
2126 arc_state = arc_state_reason = NULL;
2127 arc_received_instance = 0;
2131 deliver_host = deliver_host_address = NULL; /* Can be set by ACL */
2132 #ifndef DISABLE_PRDR
2133 prdr_requested = FALSE;
2136 message_smtputf8 = FALSE;
2138 body_linecount = body_zerocount = 0;
2140 sender_rate = sender_rate_limit = sender_rate_period = NULL;
2141 ratelimiters_mail = NULL; /* Updated by ratelimit ACL condition */
2142 /* Note that ratelimiters_conn persists across resets. */
2144 /* Reset message ACL variables */
2148 /* Warning log messages are saved in malloc store. They are saved to avoid
2149 repetition in the same message, but it seems right to repeat them for different
2152 while (acl_warn_logged)
2154 string_item *this = acl_warn_logged;
2155 acl_warn_logged = acl_warn_logged->next;
2160 store_reset(reset_point);
2163 return store_mark();
2170 /*************************************************
2171 * Initialize for incoming batched SMTP message *
2172 *************************************************/
2174 /* This function is called from smtp_setup_msg() in the case when
2175 smtp_batched_input is true. This happens when -bS is used to pass a whole batch
2176 of messages in one file with SMTP commands between them. All errors must be
2177 reported by sending a message, and only MAIL FROM, RCPT TO, and DATA are
2178 relevant. After an error on a sender, or an invalid recipient, the remainder
2179 of the message is skipped. The value of received_protocol is already set.
2182 Returns: > 0 message successfully started (reached DATA)
2183 = 0 QUIT read or end of file reached
2184 < 0 should not occur
2188 smtp_setup_batch_msg(void)
2191 rmark reset_point = store_mark();
2193 /* Save the line count at the start of each transaction - single commands
2194 like HELO and RSET count as whole transactions. */
2196 bsmtp_transaction_linecount = receive_linecount;
2198 if ((receive_feof)()) return 0; /* Treat EOF as QUIT */
2200 cancel_cutthrough_connection(TRUE, US"smtp_setup_batch_msg");
2201 reset_point = smtp_reset(reset_point); /* Reset for start of message */
2203 /* Deal with SMTP commands. This loop is exited by setting done to a POSITIVE
2204 value. The values are 2 larger than the required yield of the function. */
2209 uschar *recipient = NULL;
2210 int start, end, sender_domain, recipient_domain;
2212 switch(smtp_read_command(FALSE, GETC_BUFFER_UNLIMITED))
2214 /* The HELO/EHLO commands set sender_address_helo if they have
2215 valid data; otherwise they are ignored, except that they do
2216 a reset of the state. */
2221 check_helo(smtp_cmd_data);
2225 cancel_cutthrough_connection(TRUE, US"RSET received");
2226 reset_point = smtp_reset(reset_point);
2227 bsmtp_transaction_linecount = receive_linecount;
2231 /* The MAIL FROM command requires an address as an operand. All we
2232 do here is to parse it for syntactic correctness. The form "<>" is
2233 a special case which converts into an empty string. The start/end
2234 pointers in the original are not used further for this address, as
2235 it is the canonical extracted address which is all that is kept. */
2238 smtp_mailcmd_count++; /* Count for no-mail log */
2240 /* The function moan_smtp_batch() does not return. */
2241 moan_smtp_batch(smtp_cmd_buffer, "503 Sender already given");
2243 if (smtp_cmd_data[0] == 0)
2244 /* The function moan_smtp_batch() does not return. */
2245 moan_smtp_batch(smtp_cmd_buffer, "501 MAIL FROM must have an address operand");
2247 /* Reset to start of message */
2249 cancel_cutthrough_connection(TRUE, US"MAIL received");
2250 reset_point = smtp_reset(reset_point);
2252 /* Apply SMTP rewrite */
2254 raw_sender = rewrite_existflags & rewrite_smtp
2255 /* deconst ok as smtp_cmd_data was not const */
2256 ? US rewrite_one(smtp_cmd_data, rewrite_smtp|rewrite_smtp_sender, NULL,
2257 FALSE, US"", global_rewrite_rules)
2260 /* Extract the address; the TRUE flag allows <> as valid */
2263 parse_extract_address(raw_sender, &errmess, &start, &end, &sender_domain,
2267 /* The function moan_smtp_batch() does not return. */
2268 moan_smtp_batch(smtp_cmd_buffer, "501 %s", errmess);
2270 sender_address = string_copy(raw_sender);
2272 /* Qualify unqualified sender addresses if permitted to do so. */
2275 && sender_address[0] != 0 && sender_address[0] != '@')
2276 if (f.allow_unqualified_sender)
2278 /* deconst ok as sender_address was not const */
2279 sender_address = US rewrite_address_qualify(sender_address, FALSE);
2280 DEBUG(D_receive) debug_printf("unqualified address %s accepted "
2281 "and rewritten\n", raw_sender);
2283 /* The function moan_smtp_batch() does not return. */
2285 moan_smtp_batch(smtp_cmd_buffer, "501 sender address must contain "
2290 /* The RCPT TO command requires an address as an operand. All we do
2291 here is to parse it for syntactic correctness. There may be any number
2292 of RCPT TO commands, specifying multiple senders. We build them all into
2293 a data structure that is in argc/argv format. The start/end values
2294 given by parse_extract_address are not used, as we keep only the
2295 extracted address. */
2298 if (!sender_address)
2299 /* The function moan_smtp_batch() does not return. */
2300 moan_smtp_batch(smtp_cmd_buffer, "503 No sender yet given");
2302 if (smtp_cmd_data[0] == 0)
2303 /* The function moan_smtp_batch() does not return. */
2304 moan_smtp_batch(smtp_cmd_buffer,
2305 "501 RCPT TO must have an address operand");
2307 /* Check maximum number allowed */
2309 if (recipients_max > 0 && recipients_count + 1 > recipients_max)
2310 /* The function moan_smtp_batch() does not return. */
2311 moan_smtp_batch(smtp_cmd_buffer, "%s too many recipients",
2312 recipients_max_reject? "552": "452");
2314 /* Apply SMTP rewrite, then extract address. Don't allow "<>" as a
2315 recipient address */
2317 recipient = rewrite_existflags & rewrite_smtp
2318 /* deconst ok as smtp_cmd_data was not const */
2319 ? US rewrite_one(smtp_cmd_data, rewrite_smtp, NULL, FALSE, US"",
2320 global_rewrite_rules)
2323 recipient = parse_extract_address(recipient, &errmess, &start, &end,
2324 &recipient_domain, FALSE);
2327 /* The function moan_smtp_batch() does not return. */
2328 moan_smtp_batch(smtp_cmd_buffer, "501 %s", errmess);
2330 /* If the recipient address is unqualified, qualify it if permitted. Then
2331 add it to the list of recipients. */
2333 if (!recipient_domain)
2334 if (f.allow_unqualified_recipient)
2336 DEBUG(D_receive) debug_printf("unqualified address %s accepted\n",
2338 /* deconst ok as recipient was not const */
2339 recipient = US rewrite_address_qualify(recipient, TRUE);
2341 /* The function moan_smtp_batch() does not return. */
2343 moan_smtp_batch(smtp_cmd_buffer,
2344 "501 recipient address must contain a domain");
2346 receive_add_recipient(recipient, -1);
2350 /* The DATA command is legal only if it follows successful MAIL FROM
2351 and RCPT TO commands. This function is complete when a valid DATA
2352 command is encountered. */
2355 if (!sender_address || recipients_count <= 0)
2356 /* The function moan_smtp_batch() does not return. */
2357 if (!sender_address)
2358 moan_smtp_batch(smtp_cmd_buffer,
2359 "503 MAIL FROM:<sender> command must precede DATA");
2361 moan_smtp_batch(smtp_cmd_buffer,
2362 "503 RCPT TO:<recipient> must precede DATA");
2365 done = 3; /* DATA successfully achieved */
2366 message_ended = END_NOTENDED; /* Indicate in middle of message */
2371 /* The VRFY, EXPN, HELP, ETRN, and NOOP commands are ignored. */
2378 bsmtp_transaction_linecount = receive_linecount;
2383 f.smtp_in_quit = TRUE;
2390 /* The function moan_smtp_batch() does not return. */
2391 moan_smtp_batch(smtp_cmd_buffer, "501 Unexpected argument data");
2396 /* The function moan_smtp_batch() does not return. */
2397 moan_smtp_batch(smtp_cmd_buffer, "501 Unexpected NULL in SMTP command");
2402 /* The function moan_smtp_batch() does not return. */
2403 moan_smtp_batch(smtp_cmd_buffer, "500 Command unrecognized");
2408 return done - 2; /* Convert yield values */
2416 smtp_log_tls_fail(uschar * errstr)
2418 uschar * conn_info = smtp_get_connection_info();
2420 if (Ustrncmp(conn_info, US"SMTP ", 5) == 0) conn_info += 5;
2421 /* I'd like to get separated H= here, but too hard for now */
2423 log_write(0, LOG_MAIN, "TLS error on %s %s", conn_info, errstr);
2437 socklen_t len = sizeof(is_fastopen);
2439 /* The tinfo TCPOPT_FAST_OPEN bit seems unreliable, and we don't see state
2440 TCP_SYN_RCV (as of 12.1) so no idea about data-use. */
2442 if (getsockopt(fileno(smtp_out), IPPROTO_TCP, TCP_FASTOPEN, &is_fastopen, &len) == 0)
2447 debug_printf("TFO mode connection (TCP_FASTOPEN getsockopt)\n");
2448 f.tcp_in_fastopen = TRUE;
2451 else DEBUG(D_receive)
2452 debug_printf("TCP_INFO getsockopt: %s\n", strerror(errno));
2454 # elif defined(TCP_INFO)
2455 struct tcp_info tinfo;
2456 socklen_t len = sizeof(tinfo);
2458 if (getsockopt(fileno(smtp_out), IPPROTO_TCP, TCP_INFO, &tinfo, &len) == 0)
2459 # ifdef TCPI_OPT_SYN_DATA /* FreeBSD 11,12 do not seem to have this yet */
2460 if (tinfo.tcpi_options & TCPI_OPT_SYN_DATA)
2463 debug_printf("TFO mode connection (ACKd data-on-SYN)\n");
2464 f.tcp_in_fastopen_data = f.tcp_in_fastopen = TRUE;
2468 if (tinfo.tcpi_state == TCP_SYN_RECV) /* Not seen on FreeBSD 12.1 */
2471 debug_printf("TFO mode connection (state TCP_SYN_RECV)\n");
2472 f.tcp_in_fastopen = TRUE;
2474 else DEBUG(D_receive)
2475 debug_printf("TCP_INFO getsockopt: %s\n", strerror(errno));
2481 /*************************************************
2482 * Start an SMTP session *
2483 *************************************************/
2485 /* This function is called at the start of an SMTP session. Thereafter,
2486 smtp_setup_msg() is called to initiate each separate message. This
2487 function does host-specific testing, and outputs the banner line.
2490 Returns: FALSE if the session can not continue; something has
2491 gone wrong, or the connection to the host is blocked
2495 smtp_start_session(void)
2498 uschar *user_msg, *log_msg;
2503 gettimeofday(&smtp_connection_start, NULL);
2504 for (smtp_ch_index = 0; smtp_ch_index < SMTP_HBUFF_SIZE; smtp_ch_index++)
2505 smtp_connection_had[smtp_ch_index] = SCH_NONE;
2508 /* Default values for certain variables */
2510 fl.helo_seen = fl.esmtp = fl.helo_accept_junk = FALSE;
2511 smtp_mailcmd_count = 0;
2512 count_nonmail = TRUE_UNSET;
2513 synprot_error_count = unknown_command_count = nonmail_command_count = 0;
2514 smtp_delay_mail = smtp_rlm_base;
2515 fl.auth_advertised = FALSE;
2516 f.smtp_in_pipelining_advertised = f.smtp_in_pipelining_used = FALSE;
2517 f.pipelining_enable = TRUE;
2518 sync_cmd_limit = NON_SYNC_CMD_NON_PIPELINING;
2519 fl.smtp_exit_function_called = FALSE; /* For avoiding loop in not-quit exit */
2521 /* If receiving by -bs from a trusted user, or testing with -bh, we allow
2522 authentication settings from -oMaa to remain in force. */
2524 if (!host_checking && !f.sender_host_notsocket)
2525 sender_host_auth_pubname = sender_host_authenticated = NULL;
2526 authenticated_by = NULL;
2529 tls_in.ver = tls_in.cipher = tls_in.peerdn = NULL;
2530 tls_in.ourcert = tls_in.peercert = NULL;
2532 tls_in.ocsp = OCSP_NOT_REQ;
2533 fl.tls_advertised = FALSE;
2535 fl.dsn_advertised = FALSE;
2537 fl.smtputf8_advertised = FALSE;
2540 /* Reset ACL connection variables */
2544 /* Allow for trailing 0 in the command and data buffers. Tainted. */
2546 smtp_cmd_buffer = store_get_perm(2*SMTP_CMD_BUFFER_SIZE + 2, TRUE);
2548 smtp_cmd_buffer[0] = 0;
2549 smtp_data_buffer = smtp_cmd_buffer + SMTP_CMD_BUFFER_SIZE + 1;
2551 /* For batched input, the protocol setting can be overridden from the
2552 command line by a trusted caller. */
2554 if (smtp_batched_input)
2556 if (!received_protocol) received_protocol = US"local-bsmtp";
2559 /* For non-batched SMTP input, the protocol setting is forced here. It will be
2560 reset later if any of EHLO/AUTH/STARTTLS are received. */
2564 (sender_host_address ? protocols : protocols_local) [pnormal];
2566 /* Set up the buffer for inputting using direct read() calls, and arrange to
2567 call the local functions instead of the standard C ones. Place a NUL at the
2568 end of the buffer to safety-stop C-string reads from it. */
2570 if (!(smtp_inbuffer = US malloc(IN_BUFFER_SIZE)))
2571 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "malloc() failed for SMTP input buffer");
2572 smtp_inbuffer[IN_BUFFER_SIZE-1] = '\0';
2574 receive_getc = smtp_getc;
2575 receive_getbuf = smtp_getbuf;
2576 receive_get_cache = smtp_get_cache;
2577 receive_ungetc = smtp_ungetc;
2578 receive_feof = smtp_feof;
2579 receive_ferror = smtp_ferror;
2580 receive_smtp_buffered = smtp_buffered;
2581 lwr_receive_getc = NULL;
2582 lwr_receive_getbuf = NULL;
2583 lwr_receive_ungetc = NULL;
2584 smtp_inptr = smtp_inend = smtp_inbuffer;
2585 smtp_had_eof = smtp_had_error = 0;
2587 /* Set up the message size limit; this may be host-specific */
2589 thismessage_size_limit = expand_string_integer(message_size_limit, TRUE);
2590 if (expand_string_message)
2592 if (thismessage_size_limit == -1)
2593 log_write(0, LOG_MAIN|LOG_PANIC, "unable to expand message_size_limit: "
2594 "%s", expand_string_message);
2596 log_write(0, LOG_MAIN|LOG_PANIC, "invalid message_size_limit: "
2597 "%s", expand_string_message);
2598 smtp_closedown(US"Temporary local problem - please try later");
2602 /* When a message is input locally via the -bs or -bS options, sender_host_
2603 unknown is set unless -oMa was used to force an IP address, in which case it
2604 is checked like a real remote connection. When -bs is used from inetd, this
2605 flag is not set, causing the sending host to be checked. The code that deals
2606 with IP source routing (if configured) is never required for -bs or -bS and
2607 the flag sender_host_notsocket is used to suppress it.
2609 If smtp_accept_max and smtp_accept_reserve are set, keep some connections in
2610 reserve for certain hosts and/or networks. */
2612 if (!f.sender_host_unknown)
2615 BOOL reserved_host = FALSE;
2617 /* Look up IP options (source routing info) on the socket if this is not an
2618 -oMa "host", and if any are found, log them and drop the connection.
2620 Linux (and others now, see below) is different to everyone else, so there
2621 has to be some conditional compilation here. Versions of Linux before 2.1.15
2622 used a structure whose name was "options". Somebody finally realized that
2623 this name was silly, and it got changed to "ip_options". I use the
2624 newer name here, but there is a fudge in the script that sets up os.h
2625 to define a macro in older Linux systems.
2627 Sigh. Linux is a fast-moving target. Another generation of Linux uses
2628 glibc 2, which has chosen ip_opts for the structure name. This is now
2629 really a glibc thing rather than a Linux thing, so the condition name
2630 has been changed to reflect this. It is relevant also to GNU/Hurd.
2632 Mac OS 10.x (Darwin) is like the later glibc versions, but without the
2633 setting of the __GLIBC__ macro, so we can't detect it automatically. There's
2634 a special macro defined in the os.h file.
2636 Some DGUX versions on older hardware appear not to support IP options at
2637 all, so there is now a general macro which can be set to cut out this
2640 How to do this properly in IPv6 is not yet known. */
2642 #if !HAVE_IPV6 && !defined(NO_IP_OPTIONS)
2644 #ifdef GLIBC_IP_OPTIONS
2645 #if (!defined __GLIBC__) || (__GLIBC__ < 2)
2650 #elif defined DARWIN_IP_OPTIONS
2656 if (!host_checking && !f.sender_host_notsocket)
2659 EXIM_SOCKLEN_T optlen = sizeof(struct ip_options) + MAX_IPOPTLEN;
2660 struct ip_options *ipopt = store_get(optlen, FALSE);
2662 struct ip_opts ipoptblock;
2663 struct ip_opts *ipopt = &ipoptblock;
2664 EXIM_SOCKLEN_T optlen = sizeof(ipoptblock);
2666 struct ipoption ipoptblock;
2667 struct ipoption *ipopt = &ipoptblock;
2668 EXIM_SOCKLEN_T optlen = sizeof(ipoptblock);
2671 /* Occasional genuine failures of getsockopt() have been seen - for
2672 example, "reset by peer". Therefore, just log and give up on this
2673 call, unless the error is ENOPROTOOPT. This error is given by systems
2674 that have the interfaces but not the mechanism - e.g. GNU/Hurd at the time
2675 of writing. So for that error, carry on - we just can't do an IP options
2678 DEBUG(D_receive) debug_printf("checking for IP options\n");
2680 if (getsockopt(fileno(smtp_out), IPPROTO_IP, IP_OPTIONS, US (ipopt),
2683 if (errno != ENOPROTOOPT)
2685 log_write(0, LOG_MAIN, "getsockopt() failed from %s: %s",
2686 host_and_ident(FALSE), strerror(errno));
2687 smtp_printf("451 SMTP service not available\r\n", FALSE);
2692 /* Deal with any IP options that are set. On the systems I have looked at,
2693 the value of MAX_IPOPTLEN has been 40, meaning that there should never be
2694 more logging data than will fit in big_buffer. Nevertheless, after somebody
2695 questioned this code, I've added in some paranoid checking. */
2697 else if (optlen > 0)
2699 uschar *p = big_buffer;
2700 uschar *pend = big_buffer + big_buffer_size;
2703 struct in_addr addr;
2706 uschar *optstart = US (ipopt->__data);
2708 uschar *optstart = US (ipopt->ip_opts);
2710 uschar *optstart = US (ipopt->ipopt_list);
2713 DEBUG(D_receive) debug_printf("IP options exist\n");
2715 Ustrcpy(p, "IP options on incoming call:");
2718 for (uschar * opt = optstart; opt && opt < US (ipopt) + optlen; )
2731 if (!string_format(p, pend-p, " %s [@%s",
2732 (*opt == IPOPT_SSRR)? "SSRR" : "LSRR",
2734 inet_ntoa(*((struct in_addr *)(&(ipopt->faddr))))))
2736 inet_ntoa(ipopt->ip_dst)))
2738 inet_ntoa(ipopt->ipopt_dst)))
2746 optcount = (opt[1] - 3) / sizeof(struct in_addr);
2748 while (optcount-- > 0)
2750 memcpy(&addr, adptr, sizeof(addr));
2751 if (!string_format(p, pend - p - 1, "%s%s",
2752 (optcount == 0)? ":" : "@", inet_ntoa(addr)))
2758 adptr += sizeof(struct in_addr);
2766 if (pend - p < 4 + 3*opt[1]) { opt = NULL; break; }
2769 for (int i = 0; i < opt[1]; i++)
2770 p += sprintf(CS p, "%2.2x ", opt[i]);
2778 log_write(0, LOG_MAIN, "%s", big_buffer);
2780 /* Refuse any call with IP options. This is what tcpwrappers 7.5 does. */
2782 log_write(0, LOG_MAIN|LOG_REJECT,
2783 "connection from %s refused (IP options)", host_and_ident(FALSE));
2785 smtp_printf("554 SMTP service not available\r\n", FALSE);
2789 /* Length of options = 0 => there are no options */
2791 else DEBUG(D_receive) debug_printf("no IP options found\n");
2793 #endif /* HAVE_IPV6 && !defined(NO_IP_OPTIONS) */
2795 /* Set keep-alive in socket options. The option is on by default. This
2796 setting is an attempt to get rid of some hanging connections that stick in
2797 read() when the remote end (usually a dialup) goes away. */
2799 if (smtp_accept_keepalive && !f.sender_host_notsocket)
2800 ip_keepalive(fileno(smtp_out), sender_host_address, FALSE);
2802 /* If the current host matches host_lookup, set the name by doing a
2803 reverse lookup. On failure, sender_host_name will be NULL and
2804 host_lookup_failed will be TRUE. This may or may not be serious - optional
2807 if (verify_check_host(&host_lookup) == OK)
2809 (void)host_name_lookup();
2810 host_build_sender_fullhost();
2813 /* Delay this until we have the full name, if it is looked up. */
2815 set_process_info("handling incoming connection from %s",
2816 host_and_ident(FALSE));
2818 /* Expand smtp_receive_timeout, if needed */
2820 if (smtp_receive_timeout_s)
2823 if ( !(exp = expand_string(smtp_receive_timeout_s))
2825 || (smtp_receive_timeout = readconf_readtime(exp, 0, FALSE)) < 0
2827 log_write(0, LOG_MAIN|LOG_PANIC,
2828 "bad value for smtp_receive_timeout: '%s'", exp ? exp : US"");
2831 /* Test for explicit connection rejection */
2833 if (verify_check_host(&host_reject_connection) == OK)
2835 log_write(L_connection_reject, LOG_MAIN|LOG_REJECT, "refused connection "
2836 "from %s (host_reject_connection)", host_and_ident(FALSE));
2837 smtp_printf("554 SMTP service not available\r\n", FALSE);
2841 /* Test with TCP Wrappers if so configured. There is a problem in that
2842 hosts_ctl() returns 0 (deny) under a number of system failure circumstances,
2843 such as disks dying. In these cases, it is desirable to reject with a 4xx
2844 error instead of a 5xx error. There isn't a "right" way to detect such
2845 problems. The following kludge is used: errno is zeroed before calling
2846 hosts_ctl(). If the result is "reject", a 5xx error is given only if the
2847 value of errno is 0 or ENOENT (which happens if /etc/hosts.{allow,deny} does
2850 #ifdef USE_TCP_WRAPPERS
2852 if (!(tcp_wrappers_name = expand_string(tcp_wrappers_daemon_name)))
2853 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "Expansion of \"%s\" "
2854 "(tcp_wrappers_name) failed: %s", string_printing(tcp_wrappers_name),
2855 expand_string_message);
2857 if (!hosts_ctl(tcp_wrappers_name,
2858 sender_host_name ? CS sender_host_name : STRING_UNKNOWN,
2859 sender_host_address ? CS sender_host_address : STRING_UNKNOWN,
2860 sender_ident ? CS sender_ident : STRING_UNKNOWN))
2862 if (errno == 0 || errno == ENOENT)
2864 HDEBUG(D_receive) debug_printf("tcp wrappers rejection\n");
2865 log_write(L_connection_reject,
2866 LOG_MAIN|LOG_REJECT, "refused connection from %s "
2867 "(tcp wrappers)", host_and_ident(FALSE));
2868 smtp_printf("554 SMTP service not available\r\n", FALSE);
2872 int save_errno = errno;
2873 HDEBUG(D_receive) debug_printf("tcp wrappers rejected with unexpected "
2874 "errno value %d\n", save_errno);
2875 log_write(L_connection_reject,
2876 LOG_MAIN|LOG_REJECT, "temporarily refused connection from %s "
2877 "(tcp wrappers errno=%d)", host_and_ident(FALSE), save_errno);
2878 smtp_printf("451 Temporary local problem - please try later\r\n", FALSE);
2884 /* Check for reserved slots. The value of smtp_accept_count has already been
2885 incremented to include this process. */
2887 if (smtp_accept_max > 0 &&
2888 smtp_accept_count > smtp_accept_max - smtp_accept_reserve)
2890 if ((rc = verify_check_host(&smtp_reserve_hosts)) != OK)
2892 log_write(L_connection_reject,
2893 LOG_MAIN, "temporarily refused connection from %s: not in "
2894 "reserve list: connected=%d max=%d reserve=%d%s",
2895 host_and_ident(FALSE), smtp_accept_count - 1, smtp_accept_max,
2896 smtp_accept_reserve, (rc == DEFER)? " (lookup deferred)" : "");
2897 smtp_printf("421 %s: Too many concurrent SMTP connections; "
2898 "please try again later\r\n", FALSE, smtp_active_hostname);
2901 reserved_host = TRUE;
2904 /* If a load level above which only messages from reserved hosts are
2905 accepted is set, check the load. For incoming calls via the daemon, the
2906 check is done in the superior process if there are no reserved hosts, to
2907 save a fork. In all cases, the load average will already be available
2908 in a global variable at this point. */
2910 if (smtp_load_reserve >= 0 &&
2911 load_average > smtp_load_reserve &&
2913 verify_check_host(&smtp_reserve_hosts) != OK)
2915 log_write(L_connection_reject,
2916 LOG_MAIN, "temporarily refused connection from %s: not in "
2917 "reserve list and load average = %.2f", host_and_ident(FALSE),
2918 (double)load_average/1000.0);
2919 smtp_printf("421 %s: Too much load; please try again later\r\n", FALSE,
2920 smtp_active_hostname);
2924 /* Determine whether unqualified senders or recipients are permitted
2925 for this host. Unfortunately, we have to do this every time, in order to
2926 set the flags so that they can be inspected when considering qualifying
2927 addresses in the headers. For a site that permits no qualification, this
2928 won't take long, however. */
2930 f.allow_unqualified_sender =
2931 verify_check_host(&sender_unqualified_hosts) == OK;
2933 f.allow_unqualified_recipient =
2934 verify_check_host(&recipient_unqualified_hosts) == OK;
2936 /* Determine whether HELO/EHLO is required for this host. The requirement
2937 can be hard or soft. */
2939 fl.helo_verify_required = verify_check_host(&helo_verify_hosts) == OK;
2940 if (!fl.helo_verify_required)
2941 fl.helo_verify = verify_check_host(&helo_try_verify_hosts) == OK;
2943 /* Determine whether this hosts is permitted to send syntactic junk
2944 after a HELO or EHLO command. */
2946 fl.helo_accept_junk = verify_check_host(&helo_accept_junk_hosts) == OK;
2949 /* For batch SMTP input we are now done. */
2951 if (smtp_batched_input) return TRUE;
2953 /* If valid Proxy Protocol source is connecting, set up session.
2954 Failure will not allow any SMTP function other than QUIT. */
2956 #ifdef SUPPORT_PROXY
2957 proxy_session = FALSE;
2958 f.proxy_session_failed = FALSE;
2959 if (check_proxy_protocol_host())
2960 setup_proxy_protocol_host();
2963 /* Start up TLS if tls_on_connect is set. This is for supporting the legacy
2964 smtps port for use with older style SSL MTAs. */
2967 if (tls_in.on_connect)
2969 if (tls_server_start(&user_msg) != OK)
2970 return smtp_log_tls_fail(user_msg);
2971 cmd_list[CMD_LIST_TLS_AUTH].is_mail_cmd = TRUE;
2975 /* Run the connect ACL if it exists */
2978 if (acl_smtp_connect)
2981 if ((rc = acl_check(ACL_WHERE_CONNECT, NULL, acl_smtp_connect, &user_msg,
2984 (void) smtp_handle_acl_fail(ACL_WHERE_CONNECT, rc, user_msg, log_msg);
2989 /* Output the initial message for a two-way SMTP connection. It may contain
2990 newlines, which then cause a multi-line response to be given. */
2992 code = US"220"; /* Default status code */
2993 esc = US""; /* Default extended status code */
2994 esclen = 0; /* Length of esc */
2998 if (!(s = expand_string(smtp_banner)))
2999 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "Expansion of \"%s\" (smtp_banner) "
3000 "failed: %s", smtp_banner, expand_string_message);
3006 smtp_message_code(&code, &codelen, &s, NULL, TRUE);
3010 esclen = codelen - 4;
3014 /* Remove any terminating newlines; might as well remove trailing space too */
3017 while (p > s && isspace(p[-1])) p--;
3018 s = string_copyn(s, p-s);
3020 /* It seems that CC:Mail is braindead, and assumes that the greeting message
3021 is all contained in a single IP packet. The original code wrote out the
3022 greeting using several calls to fprint/fputc, and on busy servers this could
3023 cause it to be split over more than one packet - which caused CC:Mail to fall
3024 over when it got the second part of the greeting after sending its first
3025 command. Sigh. To try to avoid this, build the complete greeting message
3026 first, and output it in one fell swoop. This gives a better chance of it
3027 ending up as a single packet. */
3029 ss = string_get(256);
3032 do /* At least once, in case we have an empty string */
3035 uschar *linebreak = Ustrchr(p, '\n');
3036 ss = string_catn(ss, code, 3);
3040 ss = string_catn(ss, US" ", 1);
3044 len = linebreak - p;
3045 ss = string_catn(ss, US"-", 1);
3047 ss = string_catn(ss, esc, esclen);
3048 ss = string_catn(ss, p, len);
3049 ss = string_catn(ss, US"\r\n", 2);
3055 /* Before we write the banner, check that there is no input pending, unless
3056 this synchronisation check is disabled. */
3058 #ifndef DISABLE_PIPE_CONNECT
3059 fl.pipe_connect_acceptable =
3060 sender_host_address && verify_check_host(&pipe_connect_advertise_hosts) == OK;
3063 if (fl.pipe_connect_acceptable)
3064 f.smtp_in_early_pipe_used = TRUE;
3070 unsigned n = smtp_inend - smtp_inptr;
3071 if (n > 128) n = 128;
3073 log_write(0, LOG_MAIN|LOG_REJECT, "SMTP protocol "
3074 "synchronization error (input sent without waiting for greeting): "
3075 "rejected connection from %s input=\"%s\"", host_and_ident(TRUE),
3076 string_printing(string_copyn(smtp_inptr, n)));
3077 smtp_printf("554 SMTP synchronization error\r\n", FALSE);
3081 /* Now output the banner */
3082 /*XXX the ehlo-resp code does its own tls/nontls bit. Maybe subroutine that? */
3085 #ifndef DISABLE_PIPE_CONNECT
3086 fl.pipe_connect_acceptable && pipeline_connect_sends(),
3090 string_from_gstring(ss));
3092 /* Attempt to see if we sent the banner before the last ACK of the 3-way
3093 handshake arrived. If so we must have managed a TFO. */
3096 if (sender_host_address && !f.sender_host_notsocket) tfo_in_check();
3106 /*************************************************
3107 * Handle SMTP syntax and protocol errors *
3108 *************************************************/
3110 /* Write to the log for SMTP syntax errors in incoming commands, if configured
3111 to do so. Then transmit the error response. The return value depends on the
3112 number of syntax and protocol errors in this SMTP session.
3115 type error type, given as a log flag bit
3116 code response code; <= 0 means don't send a response
3117 data data to reflect in the response (can be NULL)
3118 errmess the error message
3120 Returns: -1 limit of syntax/protocol errors NOT exceeded
3121 +1 limit of syntax/protocol errors IS exceeded
3123 These values fit in with the values of the "done" variable in the main
3124 processing loop in smtp_setup_msg(). */
3127 synprot_error(int type, int code, uschar *data, uschar *errmess)
3131 log_write(type, LOG_MAIN, "SMTP %s error in \"%s\" %s %s",
3132 type == L_smtp_syntax_error ? "syntax" : "protocol",
3133 string_printing(smtp_cmd_buffer), host_and_ident(TRUE), errmess);
3135 if (++synprot_error_count > smtp_max_synprot_errors)
3138 log_write(0, LOG_MAIN|LOG_REJECT, "SMTP call from %s dropped: too many "
3139 "syntax or protocol errors (last command was \"%s\", %s)",
3140 host_and_ident(FALSE), string_printing(smtp_cmd_buffer),
3141 string_from_gstring(s_connhad_log(NULL))
3147 smtp_printf("%d%c%s%s%s\r\n", FALSE, code, yield == 1 ? '-' : ' ',
3148 data ? data : US"", data ? US": " : US"", errmess);
3150 smtp_printf("%d Too many syntax or protocol errors\r\n", FALSE, code);
3159 /*************************************************
3160 * Send SMTP response, possibly multiline *
3161 *************************************************/
3163 /* There are, it seems, broken clients out there that cannot handle multiline
3164 responses. If no_multiline_responses is TRUE (it can be set from an ACL), we
3165 output nothing for non-final calls, and only the first line for anything else.
3168 code SMTP code, may involve extended status codes
3169 codelen length of smtp code; if > 4 there's an ESC
3170 final FALSE if the last line isn't the final line
3171 msg message text, possibly containing newlines
3177 smtp_respond(uschar* code, int codelen, BOOL final, uschar *msg)
3182 if (!final && f.no_multiline_responses) return;
3187 esclen = codelen - 4;
3190 /* If this is the first output for a (non-batch) RCPT command, see if all RCPTs
3191 have had the same. Note: this code is also present in smtp_printf(). It would
3192 be tidier to have it only in one place, but when it was added, it was easier to
3193 do it that way, so as not to have to mess with the code for the RCPT command,
3194 which sometimes uses smtp_printf() and sometimes smtp_respond(). */
3196 if (fl.rcpt_in_progress)
3198 if (!rcpt_smtp_response)
3199 rcpt_smtp_response = string_copy(msg);
3200 else if (fl.rcpt_smtp_response_same &&
3201 Ustrcmp(rcpt_smtp_response, msg) != 0)
3202 fl.rcpt_smtp_response_same = FALSE;
3203 fl.rcpt_in_progress = FALSE;
3206 /* Now output the message, splitting it up into multiple lines if necessary.
3207 We only handle pipelining these responses as far as nonfinal/final groups,
3208 not the whole MAIL/RCPT/DATA response set. */
3212 uschar *nl = Ustrchr(msg, '\n');
3215 smtp_printf("%.3s%c%.*s%s\r\n", !final, code, final ? ' ':'-', esclen, esc, msg);
3218 else if (nl[1] == 0 || f.no_multiline_responses)
3220 smtp_printf("%.3s%c%.*s%.*s\r\n", !final, code, final ? ' ':'-', esclen, esc,
3221 (int)(nl - msg), msg);
3226 smtp_printf("%.3s-%.*s%.*s\r\n", TRUE, code, esclen, esc, (int)(nl - msg), msg);
3228 Uskip_whitespace(&msg);
3236 /*************************************************
3237 * Parse user SMTP message *
3238 *************************************************/
3240 /* This function allows for user messages overriding the response code details
3241 by providing a suitable response code string at the start of the message
3242 user_msg. Check the message for starting with a response code and optionally an
3243 extended status code. If found, check that the first digit is valid, and if so,
3244 change the code pointer and length to use the replacement. An invalid code
3245 causes a panic log; in this case, if the log messages is the same as the user
3246 message, we must also adjust the value of the log message to show the code that
3247 is actually going to be used (the original one).
3249 This function is global because it is called from receive.c as well as within
3252 Note that the code length returned includes the terminating whitespace
3253 character, which is always included in the regex match.
3256 code SMTP code, may involve extended status codes
3257 codelen length of smtp code; if > 4 there's an ESC
3259 log_msg optional log message, to be adjusted with the new SMTP code
3260 check_valid if true, verify the response code
3266 smtp_message_code(uschar **code, int *codelen, uschar **msg, uschar **log_msg,
3272 if (!msg || !*msg || !regex_match(regex_smtp_code, *msg, -1, &match))
3275 len = Ustrlen(match);
3276 if (check_valid && (*msg)[0] != (*code)[0])
3278 log_write(0, LOG_MAIN|LOG_PANIC, "configured error code starts with "
3279 "incorrect digit (expected %c) in \"%s\"", (*code)[0], *msg);
3280 if (log_msg && *log_msg == *msg)
3281 *log_msg = string_sprintf("%s %s", *code, *log_msg + len);
3286 *codelen = len; /* Includes final space */
3288 *msg += len; /* Chop the code off the message */
3295 /*************************************************
3296 * Handle an ACL failure *
3297 *************************************************/
3299 /* This function is called when acl_check() fails. As well as calls from within
3300 this module, it is called from receive.c for an ACL after DATA. It sorts out
3301 logging the incident, and sends the error response. A message containing
3302 newlines is turned into a multiline SMTP response, but for logging, only the
3305 There's a table of default permanent failure response codes to use in
3306 globals.c, along with the table of names. VFRY is special. Despite RFC1123 it
3307 defaults disabled in Exim. However, discussion in connection with RFC 821bis
3308 (aka RFC 2821) has concluded that the response should be 252 in the disabled
3309 state, because there are broken clients that try VRFY before RCPT. A 5xx
3310 response should be given only when the address is positively known to be
3311 undeliverable. Sigh. We return 252 if there is no VRFY ACL or it provides
3312 no explicit code, but if there is one we let it know best.
3313 Also, for ETRN, 458 is given on refusal, and for AUTH, 503.
3315 From Exim 4.63, it is possible to override the response code details by
3316 providing a suitable response code string at the start of the message provided
3317 in user_msg. The code's first digit is checked for validity.
3320 where where the ACL was called from
3322 user_msg a message that can be included in an SMTP response
3323 log_msg a message for logging
3325 Returns: 0 in most cases
3326 2 if the failure code was FAIL_DROP, in which case the
3327 SMTP connection should be dropped (this value fits with the
3328 "done" variable in smtp_setup_msg() below)
3332 smtp_handle_acl_fail(int where, int rc, uschar *user_msg, uschar *log_msg)
3334 BOOL drop = rc == FAIL_DROP;
3338 uschar *sender_info = US"";
3341 if (drop) rc = FAIL;
3343 /* Set the default SMTP code, and allow a user message to change it. */
3345 smtp_code = rc == FAIL ? acl_wherecodes[where] : US"451";
3346 smtp_message_code(&smtp_code, &codelen, &user_msg, &log_msg,
3347 where != ACL_WHERE_VRFY);
3349 /* We used to have sender_address here; however, there was a bug that was not
3350 updating sender_address after a rewrite during a verify. When this bug was
3351 fixed, sender_address at this point became the rewritten address. I'm not sure
3352 this is what should be logged, so I've changed to logging the unrewritten
3353 address to retain backward compatibility. */
3357 #ifdef WITH_CONTENT_SCAN
3358 case ACL_WHERE_MIME: what = US"during MIME ACL checks"; break;
3360 case ACL_WHERE_PREDATA: what = US"DATA"; break;
3361 case ACL_WHERE_DATA: what = US"after DATA"; break;
3362 #ifndef DISABLE_PRDR
3363 case ACL_WHERE_PRDR: what = US"after DATA PRDR"; break;
3367 uschar * place = smtp_cmd_data ? smtp_cmd_data : US"in \"connect\" ACL";
3370 if (where == ACL_WHERE_AUTH) /* avoid logging auth creds */
3373 for (s = smtp_cmd_data; *s && !isspace(*s); ) s++;
3374 lim = s - smtp_cmd_data; /* atop after method */
3376 what = string_sprintf("%s %.*s", acl_wherenames[where], lim, place);
3381 case ACL_WHERE_RCPT:
3382 case ACL_WHERE_DATA:
3383 #ifdef WITH_CONTENT_SCAN
3384 case ACL_WHERE_MIME:
3386 sender_info = string_sprintf("F=<%s>%s%s%s%s ",
3387 sender_address_unrewritten ? sender_address_unrewritten : sender_address,
3388 sender_host_authenticated ? US" A=" : US"",
3389 sender_host_authenticated ? sender_host_authenticated : US"",
3390 sender_host_authenticated && authenticated_id ? US":" : US"",
3391 sender_host_authenticated && authenticated_id ? authenticated_id : US""
3396 /* If there's been a sender verification failure with a specific message, and
3397 we have not sent a response about it yet, do so now, as a preliminary line for
3398 failures, but not defers. However, always log it for defer, and log it for fail
3399 unless the sender_verify_fail log selector has been turned off. */
3401 if (sender_verified_failed &&
3402 !testflag(sender_verified_failed, af_sverify_told))
3404 BOOL save_rcpt_in_progress = fl.rcpt_in_progress;
3405 fl.rcpt_in_progress = FALSE; /* So as not to treat these as the error */
3407 setflag(sender_verified_failed, af_sverify_told);
3409 if (rc != FAIL || LOGGING(sender_verify_fail))
3410 log_write(0, LOG_MAIN|LOG_REJECT, "%s sender verify %s for <%s>%s",
3411 host_and_ident(TRUE),
3412 ((sender_verified_failed->special_action & 255) == DEFER)? "defer":"fail",
3413 sender_verified_failed->address,
3414 (sender_verified_failed->message == NULL)? US"" :
3415 string_sprintf(": %s", sender_verified_failed->message));
3417 if (rc == FAIL && sender_verified_failed->user_message)
3418 smtp_respond(smtp_code, codelen, FALSE, string_sprintf(
3419 testflag(sender_verified_failed, af_verify_pmfail)?
3420 "Postmaster verification failed while checking <%s>\n%s\n"
3421 "Several RFCs state that you are required to have a postmaster\n"
3422 "mailbox for each mail domain. This host does not accept mail\n"
3423 "from domains whose servers reject the postmaster address."
3425 testflag(sender_verified_failed, af_verify_nsfail)?
3426 "Callback setup failed while verifying <%s>\n%s\n"
3427 "The initial connection, or a HELO or MAIL FROM:<> command was\n"
3428 "rejected. Refusing MAIL FROM:<> does not help fight spam, disregards\n"
3429 "RFC requirements, and stops you from receiving standard bounce\n"
3430 "messages. This host does not accept mail from domains whose servers\n"
3433 "Verification failed for <%s>\n%s",
3434 sender_verified_failed->address,
3435 sender_verified_failed->user_message));
3437 fl.rcpt_in_progress = save_rcpt_in_progress;
3440 /* Sort out text for logging */
3442 log_msg = log_msg ? string_sprintf(": %s", log_msg) : US"";
3443 if ((lognl = Ustrchr(log_msg, '\n'))) *lognl = 0;
3445 /* Send permanent failure response to the command, but the code used isn't
3446 always a 5xx one - see comments at the start of this function. If the original
3447 rc was FAIL_DROP we drop the connection and yield 2. */
3450 smtp_respond(smtp_code, codelen, TRUE,
3451 user_msg ? user_msg : US"Administrative prohibition");
3453 /* Send temporary failure response to the command. Don't give any details,
3454 unless acl_temp_details is set. This is TRUE for a callout defer, a "defer"
3455 verb, and for a header verify when smtp_return_error_details is set.
3457 This conditional logic is all somewhat of a mess because of the odd
3458 interactions between temp_details and return_error_details. One day it should
3459 be re-implemented in a tidier fashion. */
3462 if (f.acl_temp_details && user_msg)
3464 if ( smtp_return_error_details
3465 && sender_verified_failed
3466 && sender_verified_failed->message
3468 smtp_respond(smtp_code, codelen, FALSE, sender_verified_failed->message);
3470 smtp_respond(smtp_code, codelen, TRUE, user_msg);
3473 smtp_respond(smtp_code, codelen, TRUE,
3474 US"Temporary local problem - please try later");
3476 /* Log the incident to the logs that are specified by log_reject_target
3477 (default main, reject). This can be empty to suppress logging of rejections. If
3478 the connection is not forcibly to be dropped, return 0. Otherwise, log why it
3479 is closing if required and return 2. */
3481 if (log_reject_target != 0)
3484 gstring * g = s_tlslog(NULL);
3485 uschar * tls = string_from_gstring(g);
3486 if (!tls) tls = US"";
3488 uschar * tls = US"";
3490 log_write(where == ACL_WHERE_CONNECT ? L_connection_reject : 0,
3491 log_reject_target, "%s%s%s %s%srejected %s%s",
3492 LOGGING(dnssec) && sender_host_dnssec ? US" DS" : US"",
3493 host_and_ident(TRUE),
3496 rc == FAIL ? US"" : US"temporarily ",
3500 if (!drop) return 0;
3502 log_write(L_smtp_connection, LOG_MAIN, "%s closed by DROP in ACL",
3503 smtp_get_connection_info());
3505 /* Run the not-quit ACL, but without any custom messages. This should not be a
3506 problem, because we get here only if some other ACL has issued "drop", and
3507 in that case, *its* custom messages will have been used above. */
3509 smtp_notquit_exit(US"acl-drop", NULL, NULL);
3516 /*************************************************
3517 * Handle SMTP exit when QUIT is not given *
3518 *************************************************/
3520 /* This function provides a logging/statistics hook for when an SMTP connection
3521 is dropped on the floor or the other end goes away. It's a global function
3522 because it's called from receive.c as well as this module. As well as running
3523 the NOTQUIT ACL, if there is one, this function also outputs a final SMTP
3524 response, either with a custom message from the ACL, or using a default. There
3525 is one case, however, when no message is output - after "drop". In that case,
3526 the ACL that obeyed "drop" has already supplied the custom message, and NULL is
3527 passed to this function.
3529 In case things go wrong while processing this function, causing an error that
3530 may re-enter this function, there is a recursion check.
3533 reason What $smtp_notquit_reason will be set to in the ACL;
3534 if NULL, the ACL is not run
3535 code The error code to return as part of the response
3536 defaultrespond The default message if there's no user_msg
3542 smtp_notquit_exit(uschar *reason, uschar *code, uschar *defaultrespond, ...)
3545 uschar *user_msg = NULL;
3546 uschar *log_msg = NULL;
3548 /* Check for recursive call */
3550 if (fl.smtp_exit_function_called)
3552 log_write(0, LOG_PANIC, "smtp_notquit_exit() called more than once (%s)",
3556 fl.smtp_exit_function_called = TRUE;
3558 /* Call the not-QUIT ACL, if there is one, unless no reason is given. */
3560 if (acl_smtp_notquit && reason)
3562 smtp_notquit_reason = reason;
3563 if ((rc = acl_check(ACL_WHERE_NOTQUIT, NULL, acl_smtp_notquit, &user_msg,
3564 &log_msg)) == ERROR)
3565 log_write(0, LOG_MAIN|LOG_PANIC, "ACL for not-QUIT returned ERROR: %s",
3569 /* If the connection was dropped, we certainly are no longer talking TLS */
3570 tls_in.active.sock = -1;
3572 /* Write an SMTP response if we are expected to give one. As the default
3573 responses are all internal, they should be reasonable size. */
3575 if (code && defaultrespond)
3578 smtp_respond(code, 3, TRUE, user_msg);
3584 va_start(ap, defaultrespond);
3585 g = string_vformat(NULL, SVFMT_EXTEND|SVFMT_REBUFFER, CS defaultrespond, ap);
3587 smtp_printf("%s %s\r\n", FALSE, code, string_from_gstring(g));
3596 /*************************************************
3597 * Verify HELO argument *
3598 *************************************************/
3600 /* This function is called if helo_verify_hosts or helo_try_verify_hosts is
3601 matched. It is also called from ACL processing if verify = helo is used and
3602 verification was not previously tried (i.e. helo_try_verify_hosts was not
3603 matched). The result of its processing is to set helo_verified and
3604 helo_verify_failed. These variables should both be FALSE for this function to
3607 Note that EHLO/HELO is legitimately allowed to quote an address literal. Allow
3608 for IPv6 ::ffff: literals.
3611 Returns: TRUE if testing was completed;
3612 FALSE on a temporary failure
3616 smtp_verify_helo(void)
3620 HDEBUG(D_receive) debug_printf("verifying EHLO/HELO argument \"%s\"\n",
3623 if (sender_helo_name == NULL)
3625 HDEBUG(D_receive) debug_printf("no EHLO/HELO command was issued\n");
3628 /* Deal with the case of -bs without an IP address */
3630 else if (sender_host_address == NULL)
3632 HDEBUG(D_receive) debug_printf("no client IP address: assume success\n");
3633 f.helo_verified = TRUE;
3636 /* Deal with the more common case when there is a sending IP address */
3638 else if (sender_helo_name[0] == '[')
3640 f.helo_verified = Ustrncmp(sender_helo_name+1, sender_host_address,
3641 Ustrlen(sender_host_address)) == 0;
3644 if (!f.helo_verified)
3646 if (strncmpic(sender_host_address, US"::ffff:", 7) == 0)
3647 f.helo_verified = Ustrncmp(sender_helo_name + 1,
3648 sender_host_address + 7, Ustrlen(sender_host_address) - 7) == 0;
3653 { if (f.helo_verified) debug_printf("matched host address\n"); }
3656 /* Do a reverse lookup if one hasn't already given a positive or negative
3657 response. If that fails, or the name doesn't match, try checking with a forward
3662 if (sender_host_name == NULL && !host_lookup_failed)
3663 yield = host_name_lookup() != DEFER;
3665 /* If a host name is known, check it and all its aliases. */
3667 if (sender_host_name)
3668 if ((f.helo_verified = strcmpic(sender_host_name, sender_helo_name) == 0))
3670 sender_helo_dnssec = sender_host_dnssec;
3671 HDEBUG(D_receive) debug_printf("matched host name\n");
3675 uschar **aliases = sender_host_aliases;
3677 if ((f.helo_verified = strcmpic(*aliases++, sender_helo_name) == 0))
3679 sender_helo_dnssec = sender_host_dnssec;
3683 HDEBUG(D_receive) if (f.helo_verified)
3684 debug_printf("matched alias %s\n", *(--aliases));
3687 /* Final attempt: try a forward lookup of the helo name */
3689 if (!f.helo_verified)
3693 {.name = sender_helo_name, .address = NULL, .mx = MX_NONE, .next = NULL};
3695 {.request = US"*", .require = US""};
3697 HDEBUG(D_receive) debug_printf("getting IP address for %s\n",
3699 rc = host_find_bydns(&h, NULL, HOST_FIND_BY_A | HOST_FIND_BY_AAAA,
3700 NULL, NULL, NULL, &d, NULL, NULL);
3701 if (rc == HOST_FOUND || rc == HOST_FOUND_LOCAL)
3702 for (host_item * hh = &h; hh; hh = hh->next)
3703 if (Ustrcmp(hh->address, sender_host_address) == 0)
3705 f.helo_verified = TRUE;
3706 if (h.dnssec == DS_YES) sender_helo_dnssec = TRUE;
3708 debug_printf("IP address for %s matches calling address\n"
3709 "Forward DNS security status: %sverified\n",
3710 sender_helo_name, sender_helo_dnssec ? "" : "un");
3716 if (!f.helo_verified) f.helo_verify_failed = TRUE; /* We've tried ... */
3723 /*************************************************
3724 * Send user response message *
3725 *************************************************/
3727 /* This function is passed a default response code and a user message. It calls
3728 smtp_message_code() to check and possibly modify the response code, and then
3729 calls smtp_respond() to transmit the response. I put this into a function
3730 just to avoid a lot of repetition.
3733 code the response code
3734 user_msg the user message
3740 smtp_user_msg(uschar *code, uschar *user_msg)
3743 smtp_message_code(&code, &len, &user_msg, NULL, TRUE);
3744 smtp_respond(code, len, TRUE, user_msg);
3750 smtp_in_auth(auth_instance *au, uschar ** s, uschar ** ss)
3752 const uschar *set_id = NULL;
3755 /* Run the checking code, passing the remainder of the command line as
3756 data. Initials the $auth<n> variables as empty. Initialize $0 empty and set
3757 it as the only set numerical variable. The authenticator may set $auth<n>
3758 and also set other numeric variables. The $auth<n> variables are preferred
3759 nowadays; the numerical variables remain for backwards compatibility.
3761 Afterwards, have a go at expanding the set_id string, even if
3762 authentication failed - for bad passwords it can be useful to log the
3763 userid. On success, require set_id to expand and exist, and put it in
3764 authenticated_id. Save this in permanent store, as the working store gets
3765 reset at HELO, RSET, etc. */
3767 for (int i = 0; i < AUTH_VARS; i++) auth_vars[i] = NULL;
3769 expand_nlength[0] = 0; /* $0 contains nothing */
3771 rc = (au->info->servercode)(au, smtp_cmd_data);
3772 if (au->set_id) set_id = expand_string(au->set_id);
3773 expand_nmax = -1; /* Reset numeric variables */
3774 for (int i = 0; i < AUTH_VARS; i++) auth_vars[i] = NULL; /* Reset $auth<n> */
3776 /* The value of authenticated_id is stored in the spool file and printed in
3777 log lines. It must not contain binary zeros or newline characters. In
3778 normal use, it never will, but when playing around or testing, this error
3779 can (did) happen. To guard against this, ensure that the id contains only
3780 printing characters. */
3782 if (set_id) set_id = string_printing(set_id);
3784 /* For the non-OK cases, set up additional logging data if set_id
3788 set_id = set_id && *set_id
3789 ? string_sprintf(" (set_id=%s)", set_id) : US"";
3791 /* Switch on the result */
3796 if (!au->set_id || set_id) /* Complete success */
3798 if (set_id) authenticated_id = string_copy_perm(set_id, TRUE);
3799 sender_host_authenticated = au->name;
3800 sender_host_auth_pubname = au->public_name;
3801 authentication_failed = FALSE;
3802 authenticated_fail_id = NULL; /* Impossible to already be set? */
3805 (sender_host_address ? protocols : protocols_local)
3806 [pextend + pauthed + (tls_in.active.sock >= 0 ? pcrpted:0)];
3807 *s = *ss = US"235 Authentication succeeded";
3808 authenticated_by = au;
3812 /* Authentication succeeded, but we failed to expand the set_id string.
3813 Treat this as a temporary error. */
3815 auth_defer_msg = expand_string_message;
3819 if (set_id) authenticated_fail_id = string_copy_perm(set_id, TRUE);
3820 *s = string_sprintf("435 Unable to authenticate at present%s",
3821 auth_defer_user_msg);
3822 *ss = string_sprintf("435 Unable to authenticate at present%s: %s",
3823 set_id, auth_defer_msg);
3827 *s = *ss = US"501 Invalid base64 data";
3831 *s = *ss = US"501 Authentication cancelled";
3835 *s = *ss = US"553 Initial data not expected";
3839 if (set_id) authenticated_fail_id = string_copy_perm(set_id, TRUE);
3840 *s = US"535 Incorrect authentication data";
3841 *ss = string_sprintf("535 Incorrect authentication data%s", set_id);
3845 if (set_id) authenticated_fail_id = string_copy_perm(set_id, TRUE);
3846 *s = US"435 Internal error";
3847 *ss = string_sprintf("435 Internal error%s: return %d from authentication "
3848 "check", set_id, rc);
3860 qualify_recipient(uschar ** recipient, uschar * smtp_cmd_data, uschar * tag)
3863 if (f.allow_unqualified_recipient || strcmpic(*recipient, US"postmaster") == 0)
3865 DEBUG(D_receive) debug_printf("unqualified address %s accepted\n",
3867 rd = Ustrlen(recipient) + 1;
3868 /* deconst ok as *recipient was not const */
3869 *recipient = US rewrite_address_qualify(*recipient, TRUE);
3872 smtp_printf("501 %s: recipient address must contain a domain\r\n", FALSE,
3874 log_write(L_smtp_syntax_error,
3875 LOG_MAIN|LOG_REJECT, "unqualified %s rejected: <%s> %s%s",
3876 tag, *recipient, host_and_ident(TRUE), host_lookup_msg);
3884 smtp_quit_handler(uschar ** user_msgp, uschar ** log_msgp)
3887 f.smtp_in_quit = TRUE;
3888 incomplete_transaction_log(US"QUIT");
3890 && acl_check(ACL_WHERE_QUIT, NULL, acl_smtp_quit, user_msgp, log_msgp)
3892 log_write(0, LOG_MAIN|LOG_PANIC, "ACL for QUIT returned ERROR: %s",
3895 #ifdef EXIM_TCP_CORK
3896 (void) setsockopt(fileno(smtp_out), IPPROTO_TCP, EXIM_TCP_CORK, US &on, sizeof(on));
3900 smtp_respond(US"221", 3, TRUE, *user_msgp);
3902 smtp_printf("221 %s closing connection\r\n", FALSE, smtp_active_hostname);
3904 #ifdef SERVERSIDE_CLOSE_NOWAIT
3905 # ifndef DISABLE_TLS
3906 tls_close(NULL, TLS_SHUTDOWN_NOWAIT);
3909 log_write(L_smtp_connection, LOG_MAIN, "%s closed by QUIT",
3910 smtp_get_connection_info());
3913 # ifndef DISABLE_TLS
3914 tls_close(NULL, TLS_SHUTDOWN_WAIT);
3917 log_write(L_smtp_connection, LOG_MAIN, "%s closed by QUIT",
3918 smtp_get_connection_info());
3920 /* Pause, hoping client will FIN first so that they get the TIME_WAIT.
3921 The socket should become readble (though with no data) */
3924 int fd = fileno(smtp_in);
3926 struct timeval t_limit = {.tv_sec = 0, .tv_usec = 200*1000};
3930 (void) select(fd + 1, (SELECT_ARG2_TYPE *)&fds, NULL, NULL, &t_limit);
3932 #endif /*!DAEMON_CLOSE_NOWAIT*/
3937 smtp_rset_handler(void)
3940 incomplete_transaction_log(US"RSET");
3941 smtp_printf("250 Reset OK\r\n", FALSE);
3942 cmd_list[CMD_LIST_RSET].is_mail_cmd = FALSE;
3947 expand_mailmax(const uschar * s)
3949 if (!(s = expand_cstring(s)))
3950 log_write(0, LOG_MAIN|LOG_PANIC, "failed to expand smtp_accept_max_per_connection");
3951 return *s ? Uatoi(s) : 0;
3954 /*************************************************
3955 * Initialize for SMTP incoming message *
3956 *************************************************/
3958 /* This function conducts the initial dialogue at the start of an incoming SMTP
3959 message, and builds a list of recipients. However, if the incoming message
3960 is part of a batch (-bS option) a separate function is called since it would
3961 be messy having tests splattered about all over this function. This function
3962 therefore handles the case where interaction is occurring. The input and output
3963 files are set up in smtp_in and smtp_out.
3965 The global recipients_list is set to point to a vector of recipient_item
3966 blocks, whose number is given by recipients_count. This is extended by the
3967 receive_add_recipient() function. The global variable sender_address is set to
3968 the sender's address. The yield is +1 if a message has been successfully
3969 started, 0 if a QUIT command was encountered or the connection was refused from
3970 the particular host, or -1 if the connection was lost.
3974 Returns: > 0 message successfully started (reached DATA)
3975 = 0 QUIT read or end of file reached or call refused
3980 smtp_setup_msg(void)
3983 BOOL toomany = FALSE;
3984 BOOL discarded = FALSE;
3985 BOOL last_was_rej_mail = FALSE;
3986 BOOL last_was_rcpt = FALSE;
3987 rmark reset_point = store_mark();
3989 DEBUG(D_receive) debug_printf("smtp_setup_msg entered\n");
3991 /* Reset for start of new message. We allow one RSET not to be counted as a
3992 nonmail command, for those MTAs that insist on sending it between every
3993 message. Ditto for EHLO/HELO and for STARTTLS, to allow for going in and out of
3994 TLS between messages (an Exim client may do this if it has messages queued up
3995 for the host). Note: we do NOT reset AUTH at this point. */
3997 reset_point = smtp_reset(reset_point);
3998 message_ended = END_NOTSTARTED;
4000 chunking_state = f.chunking_offered ? CHUNKING_OFFERED : CHUNKING_NOT_OFFERED;
4002 cmd_list[CMD_LIST_RSET].is_mail_cmd = TRUE;
4003 cmd_list[CMD_LIST_HELO].is_mail_cmd = TRUE;
4004 cmd_list[CMD_LIST_EHLO].is_mail_cmd = TRUE;
4006 cmd_list[CMD_LIST_STARTTLS].is_mail_cmd = TRUE;
4009 if (lwr_receive_getc != NULL)
4011 /* This should have already happened, but if we've gotten confused,
4012 force a reset here. */
4013 DEBUG(D_receive) debug_printf("WARNING: smtp_setup_msg had to restore receive functions to lowers\n");
4014 bdat_pop_receive_functions();
4017 /* Set the local signal handler for SIGTERM - it tries to end off tidily */
4019 had_command_sigterm = 0;
4020 os_non_restarting_signal(SIGTERM, command_sigterm_handler);
4022 /* Batched SMTP is handled in a different function. */
4024 if (smtp_batched_input) return smtp_setup_batch_msg();
4027 if (smtp_in) /* Avoid pure-ACKs while in cmd pingpong phase */
4028 (void) setsockopt(fileno(smtp_in), IPPROTO_TCP, TCP_QUICKACK,
4029 US &off, sizeof(off));
4032 /* Deal with SMTP commands. This loop is exited by setting done to a POSITIVE
4033 value. The values are 2 larger than the required yield of the function. */
4037 const uschar **argv;
4038 uschar *etrn_command;
4039 uschar *etrn_serialize_key;
4041 uschar *log_msg, *smtp_code;
4042 uschar *user_msg = NULL;
4043 uschar *recipient = NULL;
4044 uschar *hello = NULL;
4046 BOOL was_rej_mail = FALSE;
4047 BOOL was_rcpt = FALSE;
4048 void (*oldsignal)(int);
4050 int start, end, sender_domain, recipient_domain;
4053 uschar *orcpt = NULL;
4058 /* Check once per STARTTLS or SSL-on-connect for a TLS AUTH */
4059 if ( tls_in.active.sock >= 0
4061 && tls_in.certificate_verified
4062 && cmd_list[CMD_LIST_TLS_AUTH].is_mail_cmd
4065 cmd_list[CMD_LIST_TLS_AUTH].is_mail_cmd = FALSE;
4067 for (auth_instance * au = auths; au; au = au->next)
4068 if (strcmpic(US"tls", au->driver_name) == 0)
4071 && (rc = acl_check(ACL_WHERE_AUTH, NULL, acl_smtp_auth,
4072 &user_msg, &log_msg)) != OK
4074 done = smtp_handle_acl_fail(ACL_WHERE_AUTH, rc, user_msg, log_msg);
4077 smtp_cmd_data = NULL;
4079 if (smtp_in_auth(au, &s, &ss) == OK)
4080 { DEBUG(D_auth) debug_printf("tls auth succeeded\n"); }
4082 { DEBUG(D_auth) debug_printf("tls auth not succeeded\n"); }
4089 switch(smtp_read_command(
4090 #ifndef DISABLE_PIPE_CONNECT
4091 !fl.pipe_connect_acceptable,
4095 GETC_BUFFER_UNLIMITED))
4097 /* The AUTH command is not permitted to occur inside a transaction, and may
4098 occur successfully only once per connection. Actually, that isn't quite
4099 true. When TLS is started, all previous information about a connection must
4100 be discarded, so a new AUTH is permitted at that time.
4102 AUTH may only be used when it has been advertised. However, it seems that
4103 there are clients that send AUTH when it hasn't been advertised, some of
4104 them even doing this after HELO. And there are MTAs that accept this. Sigh.
4105 So there's a get-out that allows this to happen.
4107 AUTH is initially labelled as a "nonmail command" so that one occurrence
4108 doesn't get counted. We change the label here so that multiple failing
4109 AUTHS will eventually hit the nonmail threshold. */
4113 authentication_failed = TRUE;
4114 cmd_list[CMD_LIST_AUTH].is_mail_cmd = FALSE;
4116 if (!fl.auth_advertised && !f.allow_auth_unadvertised)
4118 done = synprot_error(L_smtp_protocol_error, 503, NULL,
4119 US"AUTH command used when not advertised");
4122 if (sender_host_authenticated)
4124 done = synprot_error(L_smtp_protocol_error, 503, NULL,
4125 US"already authenticated");
4130 done = synprot_error(L_smtp_protocol_error, 503, NULL,
4131 US"not permitted in mail transaction");
4138 && (rc = acl_check(ACL_WHERE_AUTH, NULL, acl_smtp_auth,
4139 &user_msg, &log_msg)) != OK
4142 done = smtp_handle_acl_fail(ACL_WHERE_AUTH, rc, user_msg, log_msg);
4146 /* Find the name of the requested authentication mechanism. */
4149 for (; (c = *smtp_cmd_data) && !isspace(c); smtp_cmd_data++)
4150 if (!isalnum(c) && c != '-' && c != '_')
4152 done = synprot_error(L_smtp_syntax_error, 501, NULL,
4153 US"invalid character in authentication mechanism name");
4157 /* If not at the end of the line, we must be at white space. Terminate the
4158 name and move the pointer on to any data that may be present. */
4162 *smtp_cmd_data++ = 0;
4163 while (isspace(*smtp_cmd_data)) smtp_cmd_data++;
4166 /* Search for an authentication mechanism which is configured for use
4167 as a server and which has been advertised (unless, sigh, allow_auth_
4168 unadvertised is set). */
4172 for (au = auths; au; au = au->next)
4173 if (strcmpic(s, au->public_name) == 0 && au->server &&
4174 (au->advertised || f.allow_auth_unadvertised))
4179 c = smtp_in_auth(au, &s, &ss);
4181 smtp_printf("%s\r\n", FALSE, s);
4183 log_write(0, LOG_MAIN|LOG_REJECT, "%s authenticator failed for %s: %s",
4184 au->name, host_and_ident(FALSE), ss);
4187 done = synprot_error(L_smtp_protocol_error, 504, NULL,
4188 string_sprintf("%s authentication mechanism not supported", s));
4191 break; /* AUTH_CMD */
4193 /* The HELO/EHLO commands are permitted to appear in the middle of a
4194 session as well as at the beginning. They have the effect of a reset in
4195 addition to their other functions. Their absence at the start cannot be
4196 taken to be an error.
4200 If the EHLO command is not acceptable to the SMTP server, 501, 500,
4201 or 502 failure replies MUST be returned as appropriate. The SMTP
4202 server MUST stay in the same state after transmitting these replies
4203 that it was in before the EHLO was received.
4205 Therefore, we do not do the reset until after checking the command for
4206 acceptability. This change was made for Exim release 4.11. Previously
4207 it did the reset first. */
4220 HELO_EHLO: /* Common code for HELO and EHLO */
4221 cmd_list[CMD_LIST_HELO].is_mail_cmd = FALSE;
4222 cmd_list[CMD_LIST_EHLO].is_mail_cmd = FALSE;
4224 /* Reject the HELO if its argument was invalid or non-existent. A
4225 successful check causes the argument to be saved in malloc store. */
4227 if (!check_helo(smtp_cmd_data))
4229 smtp_printf("501 Syntactically invalid %s argument(s)\r\n", FALSE, hello);
4231 log_write(0, LOG_MAIN|LOG_REJECT, "rejected %s from %s: syntactically "
4232 "invalid argument(s): %s", hello, host_and_ident(FALSE),
4233 *smtp_cmd_argument == 0 ? US"(no argument given)" :
4234 string_printing(smtp_cmd_argument));
4236 if (++synprot_error_count > smtp_max_synprot_errors)
4238 log_write(0, LOG_MAIN|LOG_REJECT, "SMTP call from %s dropped: too many "
4239 "syntax or protocol errors (last command was \"%s\", %s)",
4240 host_and_ident(FALSE), string_printing(smtp_cmd_buffer),
4241 string_from_gstring(s_connhad_log(NULL))
4249 /* If sender_host_unknown is true, we have got here via the -bs interface,
4250 not called from inetd. Otherwise, we are running an IP connection and the
4251 host address will be set. If the helo name is the primary name of this
4252 host and we haven't done a reverse lookup, force one now. If helo_verify_required
4253 is set, ensure that the HELO name matches the actual host. If helo_verify
4254 is set, do the same check, but softly. */
4256 if (!f.sender_host_unknown)
4258 BOOL old_helo_verified = f.helo_verified;
4259 uschar *p = smtp_cmd_data;
4261 while (*p != 0 && !isspace(*p)) { *p = tolower(*p); p++; }
4264 /* Force a reverse lookup if HELO quoted something in helo_lookup_domains
4265 because otherwise the log can be confusing. */
4267 if ( !sender_host_name
4268 && match_isinlist(sender_helo_name, CUSS &helo_lookup_domains, 0,
4269 &domainlist_anchor, NULL, MCL_DOMAIN, TRUE, NULL) == OK)
4270 (void)host_name_lookup();
4272 /* Rebuild the fullhost info to include the HELO name (and the real name
4273 if it was looked up.) */
4275 host_build_sender_fullhost(); /* Rebuild */
4276 set_process_info("handling%s incoming connection from %s",
4277 tls_in.active.sock >= 0 ? " TLS" : "", host_and_ident(FALSE));
4279 /* Verify if configured. This doesn't give much security, but it does
4280 make some people happy to be able to do it. If helo_verify_required is set,
4281 (host matches helo_verify_hosts) failure forces rejection. If helo_verify
4282 is set (host matches helo_try_verify_hosts), it does not. This is perhaps
4283 now obsolescent, since the verification can now be requested selectively
4286 f.helo_verified = f.helo_verify_failed = sender_helo_dnssec = FALSE;
4287 if (fl.helo_verify_required || fl.helo_verify)
4289 BOOL tempfail = !smtp_verify_helo();
4290 if (!f.helo_verified)
4292 if (fl.helo_verify_required)
4294 smtp_printf("%d %s argument does not match calling host\r\n", FALSE,
4295 tempfail? 451 : 550, hello);
4296 log_write(0, LOG_MAIN|LOG_REJECT, "%srejected \"%s %s\" from %s",
4297 tempfail? "temporarily " : "",
4298 hello, sender_helo_name, host_and_ident(FALSE));
4299 f.helo_verified = old_helo_verified;
4300 break; /* End of HELO/EHLO processing */
4302 HDEBUG(D_all) debug_printf("%s verification failed but host is in "
4303 "helo_try_verify_hosts\n", hello);
4309 /* set up SPF context */
4310 spf_conn_init(sender_helo_name, sender_host_address);
4313 /* Apply an ACL check if one is defined; afterwards, recheck
4314 synchronization in case the client started sending in a delay. */
4317 if ((rc = acl_check(ACL_WHERE_HELO, NULL, acl_smtp_helo,
4318 &user_msg, &log_msg)) != OK)
4320 done = smtp_handle_acl_fail(ACL_WHERE_HELO, rc, user_msg, log_msg);
4321 sender_helo_name = NULL;
4322 host_build_sender_fullhost(); /* Rebuild */
4325 #ifndef DISABLE_PIPE_CONNECT
4326 else if (!fl.pipe_connect_acceptable && !check_sync())
4328 else if (!check_sync())
4332 /* Generate an OK reply. The default string includes the ident if present,
4333 and also the IP address if present. Reflecting back the ident is intended
4334 as a deterrent to mail forgers. For maximum efficiency, and also because
4335 some broken systems expect each response to be in a single packet, arrange
4336 that the entire reply is sent in one write(). */
4338 fl.auth_advertised = FALSE;
4339 f.smtp_in_pipelining_advertised = FALSE;
4341 fl.tls_advertised = FALSE;
4343 fl.dsn_advertised = FALSE;
4345 fl.smtputf8_advertised = FALSE;
4348 /* Expand the per-connection message count limit option */
4349 smtp_mailcmd_max = expand_mailmax(smtp_accept_max_per_connection);
4351 smtp_code = US"250 "; /* Default response code plus space*/
4354 /* sender_host_name below will be tainted, so save on copy when we hit it */
4355 g = string_get_tainted(24, TRUE);
4356 g = string_fmt_append(g, "%.3s %s Hello %s%s%s",
4358 smtp_active_hostname,
4359 sender_ident ? sender_ident : US"",
4360 sender_ident ? US" at " : US"",
4361 sender_host_name ? sender_host_name : sender_helo_name);
4363 if (sender_host_address)
4364 g = string_fmt_append(g, " [%s]", sender_host_address);
4367 /* A user-supplied EHLO greeting may not contain more than one line. Note
4368 that the code returned by smtp_message_code() includes the terminating
4369 whitespace character. */
4375 smtp_message_code(&smtp_code, &codelen, &user_msg, NULL, TRUE);
4376 s = string_sprintf("%.*s%s", codelen, smtp_code, user_msg);
4377 if ((ss = strpbrk(CS s, "\r\n")) != NULL)
4379 log_write(0, LOG_MAIN|LOG_PANIC, "EHLO/HELO response must not contain "
4380 "newlines: message truncated: %s", string_printing(s));
4383 g = string_cat(NULL, s);
4386 g = string_catn(g, US"\r\n", 2);
4388 /* If we received EHLO, we must create a multiline response which includes
4389 the functions supported. */
4395 /* I'm not entirely happy with this, as an MTA is supposed to check
4396 that it has enough room to accept a message of maximum size before
4397 it sends this. However, there seems little point in not sending it.
4398 The actual size check happens later at MAIL FROM time. By postponing it
4399 till then, VRFY and EXPN can be used after EHLO when space is short. */
4401 if (thismessage_size_limit > 0)
4402 g = string_fmt_append(g, "%.3s-SIZE %d\r\n", smtp_code,
4403 thismessage_size_limit);
4406 g = string_catn(g, smtp_code, 3);
4407 g = string_catn(g, US"-SIZE\r\n", 7);
4410 #ifdef EXPERIMENTAL_ESMTP_LIMITS
4411 if ( (smtp_mailcmd_max > 0 || recipients_max)
4412 && verify_check_host(&limits_advertise_hosts) == OK)
4414 g = string_fmt_append(g, "%.3s-LIMITS", smtp_code);
4415 if (smtp_mailcmd_max > 0)
4416 g = string_fmt_append(g, " MAILMAX=%d", smtp_mailcmd_max);
4418 g = string_fmt_append(g, " RCPTMAX=%d", recipients_max);
4419 g = string_catn(g, US"\r\n", 2);
4423 /* Exim does not do protocol conversion or data conversion. It is 8-bit
4424 clean; if it has an 8-bit character in its hand, it just sends it. It
4425 cannot therefore specify 8BITMIME and remain consistent with the RFCs.
4426 However, some users want this option simply in order to stop MUAs
4427 mangling messages that contain top-bit-set characters. It is therefore
4428 provided as an option. */
4430 if (accept_8bitmime)
4432 g = string_catn(g, smtp_code, 3);
4433 g = string_catn(g, US"-8BITMIME\r\n", 11);
4436 /* Advertise DSN support if configured to do so. */
4437 if (verify_check_host(&dsn_advertise_hosts) != FAIL)
4439 g = string_catn(g, smtp_code, 3);
4440 g = string_catn(g, US"-DSN\r\n", 6);
4441 fl.dsn_advertised = TRUE;
4444 /* Advertise ETRN/VRFY/EXPN if there's are ACL checking whether a host is
4445 permitted to issue them; a check is made when any host actually tries. */
4449 g = string_catn(g, smtp_code, 3);
4450 g = string_catn(g, US"-ETRN\r\n", 7);
4454 g = string_catn(g, smtp_code, 3);
4455 g = string_catn(g, US"-VRFY\r\n", 7);
4459 g = string_catn(g, smtp_code, 3);
4460 g = string_catn(g, US"-EXPN\r\n", 7);
4463 /* Exim is quite happy with pipelining, so let the other end know that
4464 it is safe to use it, unless advertising is disabled. */
4466 if ( f.pipelining_enable
4467 && verify_check_host(&pipelining_advertise_hosts) == OK)
4469 g = string_catn(g, smtp_code, 3);
4470 g = string_catn(g, US"-PIPELINING\r\n", 13);
4471 sync_cmd_limit = NON_SYNC_CMD_PIPELINING;
4472 f.smtp_in_pipelining_advertised = TRUE;
4474 #ifndef DISABLE_PIPE_CONNECT
4475 if (fl.pipe_connect_acceptable)
4477 f.smtp_in_early_pipe_advertised = TRUE;
4478 g = string_catn(g, smtp_code, 3);
4479 g = string_catn(g, US"-" EARLY_PIPE_FEATURE_NAME "\r\n", EARLY_PIPE_FEATURE_LEN+3);
4485 /* If any server authentication mechanisms are configured, advertise
4486 them if the current host is in auth_advertise_hosts. The problem with
4487 advertising always is that some clients then require users to
4488 authenticate (and aren't configurable otherwise) even though it may not
4489 be necessary (e.g. if the host is in host_accept_relay).
4491 RFC 2222 states that SASL mechanism names contain only upper case
4492 letters, so output the names in upper case, though we actually recognize
4493 them in either case in the AUTH command. */
4497 && !sender_host_authenticated
4499 && verify_check_host(&auth_advertise_hosts) == OK
4503 for (auth_instance * au = auths; au; au = au->next)
4505 au->advertised = FALSE;
4508 DEBUG(D_auth+D_expand) debug_printf_indent(
4509 "Evaluating advertise_condition for %s %s athenticator\n",
4510 au->name, au->public_name);
4511 if ( !au->advertise_condition
4512 || expand_check_condition(au->advertise_condition, au->name,
4519 g = string_catn(g, smtp_code, 3);
4520 g = string_catn(g, US"-AUTH", 5);
4522 fl.auth_advertised = TRUE;
4525 g = string_catn(g, US" ", 1);
4526 g = string_cat (g, au->public_name);
4527 while (++saveptr < g->ptr) g->s[saveptr] = toupper(g->s[saveptr]);
4528 au->advertised = TRUE;
4533 if (!first) g = string_catn(g, US"\r\n", 2);
4536 /* RFC 3030 CHUNKING */
4538 if (verify_check_host(&chunking_advertise_hosts) != FAIL)
4540 g = string_catn(g, smtp_code, 3);
4541 g = string_catn(g, US"-CHUNKING\r\n", 11);
4542 f.chunking_offered = TRUE;
4543 chunking_state = CHUNKING_OFFERED;
4546 /* Advertise TLS (Transport Level Security) aka SSL (Secure Socket Layer)
4547 if it has been included in the binary, and the host matches
4548 tls_advertise_hosts. We must *not* advertise if we are already in a
4549 secure connection. */
4552 if (tls_in.active.sock < 0 &&
4553 verify_check_host(&tls_advertise_hosts) != FAIL)
4555 g = string_catn(g, smtp_code, 3);
4556 g = string_catn(g, US"-STARTTLS\r\n", 11);
4557 fl.tls_advertised = TRUE;
4561 #ifndef DISABLE_PRDR
4562 /* Per Recipient Data Response, draft by Eric A. Hall extending RFC */
4565 g = string_catn(g, smtp_code, 3);
4566 g = string_catn(g, US"-PRDR\r\n", 7);
4571 if ( accept_8bitmime
4572 && verify_check_host(&smtputf8_advertise_hosts) != FAIL)
4574 g = string_catn(g, smtp_code, 3);
4575 g = string_catn(g, US"-SMTPUTF8\r\n", 11);
4576 fl.smtputf8_advertised = TRUE;
4580 /* Finish off the multiline reply with one that is always available. */
4582 g = string_catn(g, smtp_code, 3);
4583 g = string_catn(g, US" HELP\r\n", 7);
4586 /* Terminate the string (for debug), write it, and note that HELO/EHLO
4590 if (tls_in.active.sock >= 0)
4591 (void)tls_write(NULL, g->s, g->ptr,
4592 # ifndef DISABLE_PIPE_CONNECT
4593 fl.pipe_connect_acceptable && pipeline_connect_sends());
4599 (void) fwrite(g->s, 1, g->ptr, smtp_out);
4605 (void) string_from_gstring(g);
4606 while ((cr = Ustrchr(g->s, '\r')) != NULL) /* lose CRs */
4607 memmove(cr, cr + 1, (g->ptr--) - (cr - g->s));
4608 debug_printf("SMTP>> %s", g->s);
4610 fl.helo_seen = TRUE;
4612 /* Reset the protocol and the state, abandoning any previous message. */
4614 (sender_host_address ? protocols : protocols_local)
4616 ? pextend + (sender_host_authenticated ? pauthed : 0)
4618 + (tls_in.active.sock >= 0 ? pcrpted : 0)
4620 cancel_cutthrough_connection(TRUE, US"sent EHLO response");
4621 reset_point = smtp_reset(reset_point);
4623 break; /* HELO/EHLO */
4626 /* The MAIL command requires an address as an operand. All we do
4627 here is to parse it for syntactic correctness. The form "<>" is
4628 a special case which converts into an empty string. The start/end
4629 pointers in the original are not used further for this address, as
4630 it is the canonical extracted address which is all that is kept. */
4634 smtp_mailcmd_count++; /* Count for limit and ratelimit */
4636 was_rej_mail = TRUE; /* Reset if accepted */
4637 env_mail_type_t * mail_args; /* Sanity check & validate args */
4640 if ( fl.helo_verify_required
4641 || verify_check_host(&hosts_require_helo) == OK)
4643 smtp_printf("503 HELO or EHLO required\r\n", FALSE);
4644 log_write(0, LOG_MAIN|LOG_REJECT, "rejected MAIL from %s: no "
4645 "HELO/EHLO given", host_and_ident(FALSE));
4648 else if (smtp_mailcmd_max < 0)
4649 smtp_mailcmd_max = expand_mailmax(smtp_accept_max_per_connection);
4653 done = synprot_error(L_smtp_protocol_error, 503, NULL,
4654 US"sender already given");
4658 if (!*smtp_cmd_data)
4660 done = synprot_error(L_smtp_protocol_error, 501, NULL,
4661 US"MAIL must have an address operand");
4665 /* Check to see if the limit for messages per connection would be
4666 exceeded by accepting further messages. */
4668 if (smtp_mailcmd_max > 0 && smtp_mailcmd_count > smtp_mailcmd_max)
4670 smtp_printf("421 too many messages in this connection\r\n", FALSE);
4671 log_write(0, LOG_MAIN|LOG_REJECT, "rejected MAIL command %s: too many "
4672 "messages in one connection", host_and_ident(TRUE));
4676 /* Reset for start of message - even if this is going to fail, we
4677 obviously need to throw away any previous data. */
4679 cancel_cutthrough_connection(TRUE, US"MAIL received");
4680 reset_point = smtp_reset(reset_point);
4682 sender_data = recipient_data = NULL;
4684 /* Loop, checking for ESMTP additions to the MAIL FROM command. */
4686 if (fl.esmtp) for(;;)
4688 uschar *name, *value, *end;
4689 unsigned long int size;
4690 BOOL arg_error = FALSE;
4692 if (!extract_option(&name, &value)) break;
4694 for (mail_args = env_mail_type_list;
4695 mail_args->value != ENV_MAIL_OPT_NULL;
4698 if (strcmpic(name, mail_args->name) == 0)
4700 if (mail_args->need_value && strcmpic(value, US"") == 0)
4703 switch(mail_args->value)
4705 /* Handle SIZE= by reading the value. We don't do the check till later,
4706 in order to be able to log the sender address on failure. */
4707 case ENV_MAIL_OPT_SIZE:
4708 if (((size = Ustrtoul(value, &end, 10)), *end == 0))
4710 if ((size == ULONG_MAX && errno == ERANGE) || size > INT_MAX)
4712 message_size = (int)size;
4718 /* If this session was initiated with EHLO and accept_8bitmime is set,
4719 Exim will have indicated that it supports the BODY=8BITMIME option. In
4720 fact, it does not support this according to the RFCs, in that it does not
4721 take any special action for forwarding messages containing 8-bit
4722 characters. That is why accept_8bitmime is not the default setting, but
4723 some sites want the action that is provided. We recognize both "8BITMIME"
4724 and "7BIT" as body types, but take no action. */
4725 case ENV_MAIL_OPT_BODY:
4726 if (accept_8bitmime) {
4727 if (strcmpic(value, US"8BITMIME") == 0)
4729 else if (strcmpic(value, US"7BIT") == 0)
4734 done = synprot_error(L_smtp_syntax_error, 501, NULL,
4735 US"invalid data for BODY");
4738 DEBUG(D_receive) debug_printf("8BITMIME: %d\n", body_8bitmime);
4744 /* Handle the two DSN options, but only if configured to do so (which
4745 will have caused "DSN" to be given in the EHLO response). The code itself
4746 is included only if configured in at build time. */
4748 case ENV_MAIL_OPT_RET:
4749 if (fl.dsn_advertised)
4751 /* Check if RET has already been set */
4754 done = synprot_error(L_smtp_syntax_error, 501, NULL,
4755 US"RET can be specified once only");
4758 dsn_ret = strcmpic(value, US"HDRS") == 0
4760 : strcmpic(value, US"FULL") == 0
4763 DEBUG(D_receive) debug_printf("DSN_RET: %d\n", dsn_ret);
4764 /* Check for invalid invalid value, and exit with error */
4767 done = synprot_error(L_smtp_syntax_error, 501, NULL,
4768 US"Value for RET is invalid");
4773 case ENV_MAIL_OPT_ENVID:
4774 if (fl.dsn_advertised)
4776 /* Check if the dsn envid has been already set */
4779 done = synprot_error(L_smtp_syntax_error, 501, NULL,
4780 US"ENVID can be specified once only");
4783 dsn_envid = string_copy(value);
4784 DEBUG(D_receive) debug_printf("DSN_ENVID: %s\n", dsn_envid);
4788 /* Handle the AUTH extension. If the value given is not "<>" and either
4789 the ACL says "yes" or there is no ACL but the sending host is
4790 authenticated, we set it up as the authenticated sender. However, if the
4791 authenticator set a condition to be tested, we ignore AUTH on MAIL unless
4792 the condition is met. The value of AUTH is an xtext, which means that +,
4793 = and cntrl chars are coded in hex; however "<>" is unaffected by this
4795 case ENV_MAIL_OPT_AUTH:
4796 if (Ustrcmp(value, "<>") != 0)
4801 if (auth_xtextdecode(value, &authenticated_sender) < 0)
4803 /* Put back terminator overrides for error message */
4806 done = synprot_error(L_smtp_syntax_error, 501, NULL,
4807 US"invalid data for AUTH");
4810 if (!acl_smtp_mailauth)
4812 ignore_msg = US"client not authenticated";
4813 rc = sender_host_authenticated ? OK : FAIL;
4817 ignore_msg = US"rejected by ACL";
4818 rc = acl_check(ACL_WHERE_MAILAUTH, NULL, acl_smtp_mailauth,
4819 &user_msg, &log_msg);
4825 if (authenticated_by == NULL ||
4826 authenticated_by->mail_auth_condition == NULL ||
4827 expand_check_condition(authenticated_by->mail_auth_condition,
4828 authenticated_by->name, US"authenticator"))
4829 break; /* Accept the AUTH */
4831 ignore_msg = US"server_mail_auth_condition failed";
4832 if (authenticated_id != NULL)
4833 ignore_msg = string_sprintf("%s: authenticated ID=\"%s\"",
4834 ignore_msg, authenticated_id);
4839 authenticated_sender = NULL;
4840 log_write(0, LOG_MAIN, "ignoring AUTH=%s from %s (%s)",
4841 value, host_and_ident(TRUE), ignore_msg);
4844 /* Should only get DEFER or ERROR here. Put back terminator
4845 overrides for error message */
4850 (void)smtp_handle_acl_fail(ACL_WHERE_MAILAUTH, rc, user_msg,
4857 #ifndef DISABLE_PRDR
4858 case ENV_MAIL_OPT_PRDR:
4860 prdr_requested = TRUE;
4865 case ENV_MAIL_OPT_UTF8:
4866 if (!fl.smtputf8_advertised)
4868 done = synprot_error(L_smtp_syntax_error, 501, NULL,
4869 US"SMTPUTF8 used when not advertised");
4873 DEBUG(D_receive) debug_printf("smtputf8 requested\n");
4874 message_smtputf8 = allow_utf8_domains = TRUE;
4875 if (Ustrncmp(received_protocol, US"utf8", 4) != 0)
4877 int old_pool = store_pool;
4878 store_pool = POOL_PERM;
4879 received_protocol = string_sprintf("utf8%s", received_protocol);
4880 store_pool = old_pool;
4885 /* No valid option. Stick back the terminator characters and break
4886 the loop. Do the name-terminator second as extract_option sets
4887 value==name when it found no equal-sign.
4888 An error for a malformed address will occur. */
4889 case ENV_MAIL_OPT_NULL:
4897 /* Break out of for loop if switch() had bad argument or
4898 when start of the email address is reached */
4899 if (arg_error) break;
4902 /* If we have passed the threshold for rate limiting, apply the current
4903 delay, and update it for next time, provided this is a limited host. */
4905 if (smtp_mailcmd_count > smtp_rlm_threshold &&
4906 verify_check_host(&smtp_ratelimit_hosts) == OK)
4908 DEBUG(D_receive) debug_printf("rate limit MAIL: delay %.3g sec\n",
4909 smtp_delay_mail/1000.0);
4910 millisleep((int)smtp_delay_mail);
4911 smtp_delay_mail *= smtp_rlm_factor;
4912 if (smtp_delay_mail > (double)smtp_rlm_limit)
4913 smtp_delay_mail = (double)smtp_rlm_limit;
4916 /* Now extract the address, first applying any SMTP-time rewriting. The
4917 TRUE flag allows "<>" as a sender address. */
4919 raw_sender = rewrite_existflags & rewrite_smtp
4920 /* deconst ok as smtp_cmd_data was not const */
4921 ? US rewrite_one(smtp_cmd_data, rewrite_smtp, NULL, FALSE, US"",
4922 global_rewrite_rules)
4926 parse_extract_address(raw_sender, &errmess, &start, &end, &sender_domain,
4931 done = synprot_error(L_smtp_syntax_error, 501, smtp_cmd_data, errmess);
4935 sender_address = raw_sender;
4937 /* If there is a configured size limit for mail, check that this message
4938 doesn't exceed it. The check is postponed to this point so that the sender
4941 if (thismessage_size_limit > 0 && message_size > thismessage_size_limit)
4943 smtp_printf("552 Message size exceeds maximum permitted\r\n", FALSE);
4944 log_write(L_size_reject,
4945 LOG_MAIN|LOG_REJECT, "rejected MAIL FROM:<%s> %s: "
4946 "message too big: size%s=%d max=%d",
4948 host_and_ident(TRUE),
4949 (message_size == INT_MAX)? ">" : "",
4951 thismessage_size_limit);
4952 sender_address = NULL;
4956 /* Check there is enough space on the disk unless configured not to.
4957 When smtp_check_spool_space is set, the check is for thismessage_size_limit
4958 plus the current message - i.e. we accept the message only if it won't
4959 reduce the space below the threshold. Add 5000 to the size to allow for
4960 overheads such as the Received: line and storing of recipients, etc.
4961 By putting the check here, even when SIZE is not given, it allow VRFY
4962 and EXPN etc. to be used when space is short. */
4964 if (!receive_check_fs(
4965 smtp_check_spool_space && message_size >= 0
4966 ? message_size + 5000 : 0))
4968 smtp_printf("452 Space shortage, please try later\r\n", FALSE);
4969 sender_address = NULL;
4973 /* If sender_address is unqualified, reject it, unless this is a locally
4974 generated message, or the sending host or net is permitted to send
4975 unqualified addresses - typically local machines behaving as MUAs -
4976 in which case just qualify the address. The flag is set above at the start
4977 of the SMTP connection. */
4979 if (!sender_domain && *sender_address)
4980 if (f.allow_unqualified_sender)
4982 sender_domain = Ustrlen(sender_address) + 1;
4983 /* deconst ok as sender_address was not const */
4984 sender_address = US rewrite_address_qualify(sender_address, FALSE);
4985 DEBUG(D_receive) debug_printf("unqualified address %s accepted\n",
4990 smtp_printf("501 %s: sender address must contain a domain\r\n", FALSE,
4992 log_write(L_smtp_syntax_error,
4993 LOG_MAIN|LOG_REJECT,
4994 "unqualified sender rejected: <%s> %s%s",
4996 host_and_ident(TRUE),
4998 sender_address = NULL;
5002 /* Apply an ACL check if one is defined, before responding. Afterwards,
5003 when pipelining is not advertised, do another sync check in case the ACL
5004 delayed and the client started sending in the meantime. */
5008 rc = acl_check(ACL_WHERE_MAIL, NULL, acl_smtp_mail, &user_msg, &log_msg);
5009 if (rc == OK && !f.smtp_in_pipelining_advertised && !check_sync())
5015 if (rc == OK || rc == DISCARD)
5017 BOOL more = pipeline_response();
5020 smtp_printf("%s%s%s", more, US"250 OK",
5021 #ifndef DISABLE_PRDR
5022 prdr_requested ? US", PRDR Requested" : US"",
5029 #ifndef DISABLE_PRDR
5031 user_msg = string_sprintf("%s%s", user_msg, US", PRDR Requested");
5033 smtp_user_msg(US"250", user_msg);
5035 smtp_delay_rcpt = smtp_rlr_base;
5036 f.recipients_discarded = (rc == DISCARD);
5037 was_rej_mail = FALSE;
5041 done = smtp_handle_acl_fail(ACL_WHERE_MAIL, rc, user_msg, log_msg);
5042 sender_address = NULL;
5047 /* The RCPT command requires an address as an operand. There may be any
5048 number of RCPT commands, specifying multiple recipients. We build them all
5049 into a data structure. The start/end values given by parse_extract_address
5050 are not used, as we keep only the extracted address. */
5054 /* We got really to many recipients. A check against configured
5055 limits is done later */
5056 if (rcpt_count < 0 || rcpt_count >= INT_MAX/2)
5057 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "Too many recipients: %d", rcpt_count);
5059 was_rcpt = fl.rcpt_in_progress = TRUE;
5061 /* There must be a sender address; if the sender was rejected and
5062 pipelining was advertised, we assume the client was pipelining, and do not
5063 count this as a protocol error. Reset was_rej_mail so that further RCPTs
5064 get the same treatment. */
5066 if (sender_address == NULL)
5068 if (f.smtp_in_pipelining_advertised && last_was_rej_mail)
5070 smtp_printf("503 sender not yet given\r\n", FALSE);
5071 was_rej_mail = TRUE;
5075 done = synprot_error(L_smtp_protocol_error, 503, NULL,
5076 US"sender not yet given");
5077 was_rcpt = FALSE; /* Not a valid RCPT */
5083 /* Check for an operand */
5085 if (smtp_cmd_data[0] == 0)
5087 done = synprot_error(L_smtp_syntax_error, 501, NULL,
5088 US"RCPT must have an address operand");
5093 /* Set the DSN flags orcpt and dsn_flags from the session*/
5097 if (fl.esmtp) for(;;)
5099 uschar *name, *value;
5101 if (!extract_option(&name, &value))
5104 if (fl.dsn_advertised && strcmpic(name, US"ORCPT") == 0)
5106 /* Check whether orcpt has been already set */
5109 done = synprot_error(L_smtp_syntax_error, 501, NULL,
5110 US"ORCPT can be specified once only");
5113 orcpt = string_copy(value);
5114 DEBUG(D_receive) debug_printf("DSN orcpt: %s\n", orcpt);
5117 else if (fl.dsn_advertised && strcmpic(name, US"NOTIFY") == 0)
5119 /* Check if the notify flags have been already set */
5122 done = synprot_error(L_smtp_syntax_error, 501, NULL,
5123 US"NOTIFY can be specified once only");
5126 if (strcmpic(value, US"NEVER") == 0)
5127 dsn_flags |= rf_notify_never;
5134 while (*pp != 0 && *pp != ',') pp++;
5135 if (*pp == ',') *pp++ = 0;
5136 if (strcmpic(p, US"SUCCESS") == 0)
5138 DEBUG(D_receive) debug_printf("DSN: Setting notify success\n");
5139 dsn_flags |= rf_notify_success;
5141 else if (strcmpic(p, US"FAILURE") == 0)
5143 DEBUG(D_receive) debug_printf("DSN: Setting notify failure\n");
5144 dsn_flags |= rf_notify_failure;
5146 else if (strcmpic(p, US"DELAY") == 0)
5148 DEBUG(D_receive) debug_printf("DSN: Setting notify delay\n");
5149 dsn_flags |= rf_notify_delay;
5153 /* Catch any strange values */
5154 done = synprot_error(L_smtp_syntax_error, 501, NULL,
5155 US"Invalid value for NOTIFY parameter");
5160 DEBUG(D_receive) debug_printf("DSN Flags: %x\n", dsn_flags);
5164 /* Unknown option. Stick back the terminator characters and break
5165 the loop. An error for a malformed address will occur. */
5169 DEBUG(D_receive) debug_printf("Invalid RCPT option: %s : %s\n", name, value);
5176 /* Apply SMTP rewriting then extract the working address. Don't allow "<>"
5177 as a recipient address */
5179 recipient = rewrite_existflags & rewrite_smtp
5180 /* deconst ok as smtp_cmd_data was not const */
5181 ? US rewrite_one(smtp_cmd_data, rewrite_smtp, NULL, FALSE, US"",
5182 global_rewrite_rules)
5185 if (!(recipient = parse_extract_address(recipient, &errmess, &start, &end,
5186 &recipient_domain, FALSE)))
5188 done = synprot_error(L_smtp_syntax_error, 501, smtp_cmd_data, errmess);
5193 /* If the recipient address is unqualified, reject it, unless this is a
5194 locally generated message. However, unqualified addresses are permitted
5195 from a configured list of hosts and nets - typically when behaving as
5196 MUAs rather than MTAs. Sad that SMTP is used for both types of traffic,
5197 really. The flag is set at the start of the SMTP connection.
5199 RFC 1123 talks about supporting "the reserved mailbox postmaster"; I always
5200 assumed this meant "reserved local part", but the revision of RFC 821 and
5201 friends now makes it absolutely clear that it means *mailbox*. Consequently
5202 we must always qualify this address, regardless. */
5204 if (!recipient_domain)
5205 if (!(recipient_domain = qualify_recipient(&recipient, smtp_cmd_data,
5212 /* Check maximum allowed */
5214 if (rcpt_count+1 < 0 || rcpt_count > recipients_max && recipients_max > 0)
5216 if (recipients_max_reject)
5219 smtp_printf("552 too many recipients\r\n", FALSE);
5221 log_write(0, LOG_MAIN|LOG_REJECT, "too many recipients: message "
5222 "rejected: sender=<%s> %s", sender_address, host_and_ident(TRUE));
5227 smtp_printf("452 too many recipients\r\n", FALSE);
5229 log_write(0, LOG_MAIN|LOG_REJECT, "too many recipients: excess "
5230 "temporarily rejected: sender=<%s> %s", sender_address,
5231 host_and_ident(TRUE));
5238 /* If we have passed the threshold for rate limiting, apply the current
5239 delay, and update it for next time, provided this is a limited host. */
5241 if (rcpt_count > smtp_rlr_threshold &&
5242 verify_check_host(&smtp_ratelimit_hosts) == OK)
5244 DEBUG(D_receive) debug_printf("rate limit RCPT: delay %.3g sec\n",
5245 smtp_delay_rcpt/1000.0);
5246 millisleep((int)smtp_delay_rcpt);
5247 smtp_delay_rcpt *= smtp_rlr_factor;
5248 if (smtp_delay_rcpt > (double)smtp_rlr_limit)
5249 smtp_delay_rcpt = (double)smtp_rlr_limit;
5252 /* If the MAIL ACL discarded all the recipients, we bypass ACL checking
5253 for them. Otherwise, check the access control list for this recipient. As
5254 there may be a delay in this, re-check for a synchronization error
5255 afterwards, unless pipelining was advertised. */
5257 if (f.recipients_discarded)
5260 if ( (rc = acl_check(ACL_WHERE_RCPT, recipient, acl_smtp_rcpt, &user_msg,
5262 && !f.smtp_in_pipelining_advertised && !check_sync())
5265 /* The ACL was happy */
5269 BOOL more = pipeline_response();
5272 smtp_user_msg(US"250", user_msg);
5274 smtp_printf("250 Accepted\r\n", more);
5275 receive_add_recipient(recipient, -1);
5277 /* Set the dsn flags in the recipients_list */
5278 recipients_list[recipients_count-1].orcpt = orcpt;
5279 recipients_list[recipients_count-1].dsn_flags = dsn_flags;
5281 /* DEBUG(D_receive) debug_printf("DSN: orcpt: %s flags: %d\n",
5282 recipients_list[recipients_count-1].orcpt,
5283 recipients_list[recipients_count-1].dsn_flags); */
5286 /* The recipient was discarded */
5288 else if (rc == DISCARD)
5291 smtp_user_msg(US"250", user_msg);
5293 smtp_printf("250 Accepted\r\n", FALSE);
5296 log_write(0, LOG_MAIN|LOG_REJECT, "%s F=<%s> RCPT %s: "
5297 "discarded by %s ACL%s%s", host_and_ident(TRUE),
5298 sender_address_unrewritten ? sender_address_unrewritten : sender_address,
5299 smtp_cmd_argument, f.recipients_discarded ? "MAIL" : "RCPT",
5300 log_msg ? US": " : US"", log_msg ? log_msg : US"");
5303 /* Either the ACL failed the address, or it was deferred. */
5307 if (rc == FAIL) rcpt_fail_count++; else rcpt_defer_count++;
5308 done = smtp_handle_acl_fail(ACL_WHERE_RCPT, rc, user_msg, log_msg);
5313 /* The DATA command is legal only if it follows successful MAIL FROM
5314 and RCPT TO commands. However, if pipelining is advertised, a bad DATA is
5315 not counted as a protocol error if it follows RCPT (which must have been
5316 rejected if there are no recipients.) This function is complete when a
5317 valid DATA command is encountered.
5319 Note concerning the code used: RFC 2821 says this:
5321 - If there was no MAIL, or no RCPT, command, or all such commands
5322 were rejected, the server MAY return a "command out of sequence"
5323 (503) or "no valid recipients" (554) reply in response to the
5326 The example in the pipelining RFC 2920 uses 554, but I use 503 here
5327 because it is the same whether pipelining is in use or not.
5329 If all the RCPT commands that precede DATA provoked the same error message
5330 (often indicating some kind of system error), it is helpful to include it
5331 with the DATA rejection (an idea suggested by Tony Finch). */
5338 if (chunking_state != CHUNKING_OFFERED)
5340 done = synprot_error(L_smtp_protocol_error, 503, NULL,
5341 US"BDAT command used when CHUNKING not advertised");
5345 /* grab size, endmarker */
5347 if (sscanf(CS smtp_cmd_data, "%u %n", &chunking_datasize, &n) < 1)
5349 done = synprot_error(L_smtp_protocol_error, 501, NULL,
5350 US"missing size for BDAT command");
5353 chunking_state = strcmpic(smtp_cmd_data+n, US"LAST") == 0
5354 ? CHUNKING_LAST : CHUNKING_ACTIVE;
5355 chunking_data_left = chunking_datasize;
5356 DEBUG(D_receive) debug_printf("chunking state %d, %d bytes\n",
5357 (int)chunking_state, chunking_data_left);
5359 f.bdat_readers_wanted = TRUE; /* FIXME: redundant vs chunking_state? */
5368 f.bdat_readers_wanted = FALSE;
5370 DATA_BDAT: /* Common code for DATA and BDAT */
5371 #ifndef DISABLE_PIPE_CONNECT
5372 fl.pipe_connect_acceptable = FALSE;
5374 if (!discarded && recipients_count <= 0)
5376 if (fl.rcpt_smtp_response_same && rcpt_smtp_response != NULL)
5378 uschar *code = US"503";
5379 int len = Ustrlen(rcpt_smtp_response);
5380 smtp_respond(code, 3, FALSE, US"All RCPT commands were rejected with "
5382 /* Responses from smtp_printf() will have \r\n on the end */
5383 if (len > 2 && rcpt_smtp_response[len-2] == '\r')
5384 rcpt_smtp_response[len-2] = 0;
5385 smtp_respond(code, 3, FALSE, rcpt_smtp_response);
5387 if (f.smtp_in_pipelining_advertised && last_was_rcpt)
5388 smtp_printf("503 Valid RCPT command must precede %s\r\n", FALSE,
5389 smtp_names[smtp_connection_had[SMTP_HBUFF_PREV(smtp_ch_index)]]);
5391 done = synprot_error(L_smtp_protocol_error, 503, NULL,
5392 smtp_connection_had[SMTP_HBUFF_PREV(smtp_ch_index)] == SCH_DATA
5393 ? US"valid RCPT command must precede DATA"
5394 : US"valid RCPT command must precede BDAT");
5396 if (chunking_state > CHUNKING_OFFERED)
5398 bdat_push_receive_functions();
5404 if (toomany && recipients_max_reject)
5406 sender_address = NULL; /* This will allow a new MAIL without RSET */
5407 sender_address_unrewritten = NULL;
5408 smtp_printf("554 Too many recipients\r\n", FALSE);
5410 if (chunking_state > CHUNKING_OFFERED)
5412 bdat_push_receive_functions();
5418 if (chunking_state > CHUNKING_OFFERED)
5419 rc = OK; /* No predata ACL or go-ahead output for BDAT */
5422 /* If there is an ACL, re-check the synchronization afterwards, since the
5423 ACL may have delayed. To handle cutthrough delivery enforce a dummy call
5424 to get the DATA command sent. */
5426 if (acl_smtp_predata == NULL && cutthrough.cctx.sock < 0)
5430 uschar * acl = acl_smtp_predata ? acl_smtp_predata : US"accept";
5431 f.enable_dollar_recipients = TRUE;
5432 rc = acl_check(ACL_WHERE_PREDATA, NULL, acl, &user_msg,
5434 f.enable_dollar_recipients = FALSE;
5435 if (rc == OK && !check_sync())
5439 { /* Either the ACL failed the address, or it was deferred. */
5440 done = smtp_handle_acl_fail(ACL_WHERE_PREDATA, rc, user_msg, log_msg);
5446 smtp_user_msg(US"354", user_msg);
5449 "354 Enter message, ending with \".\" on a line by itself\r\n", FALSE);
5452 if (f.bdat_readers_wanted)
5453 bdat_push_receive_functions();
5456 if (smtp_in) /* all ACKs needed to ramp window up for bulk data */
5457 (void) setsockopt(fileno(smtp_in), IPPROTO_TCP, TCP_QUICKACK,
5458 US &on, sizeof(on));
5461 message_ended = END_NOTENDED; /* Indicate in middle of data */
5472 if (!(address = parse_extract_address(smtp_cmd_data, &errmess,
5473 &start, &end, &recipient_domain, FALSE)))
5475 smtp_printf("501 %s\r\n", FALSE, errmess);
5479 if (!recipient_domain)
5480 if (!(recipient_domain = qualify_recipient(&address, smtp_cmd_data,
5484 if ((rc = acl_check(ACL_WHERE_VRFY, address, acl_smtp_vrfy,
5485 &user_msg, &log_msg)) != OK)
5486 done = smtp_handle_acl_fail(ACL_WHERE_VRFY, rc, user_msg, log_msg);
5490 address_item * addr = deliver_make_addr(address, FALSE);
5492 switch(verify_address(addr, NULL, vopt_is_recipient | vopt_qualify, -1,
5493 -1, -1, NULL, NULL, NULL))
5496 s = string_sprintf("250 <%s> is deliverable", address);
5500 s = (addr->user_message != NULL)?
5501 string_sprintf("451 <%s> %s", address, addr->user_message) :
5502 string_sprintf("451 Cannot resolve <%s> at this time", address);
5506 s = (addr->user_message != NULL)?
5507 string_sprintf("550 <%s> %s", address, addr->user_message) :
5508 string_sprintf("550 <%s> is not deliverable", address);
5509 log_write(0, LOG_MAIN, "VRFY failed for %s %s",
5510 smtp_cmd_argument, host_and_ident(TRUE));
5514 smtp_printf("%s\r\n", FALSE, s);
5522 rc = acl_check(ACL_WHERE_EXPN, NULL, acl_smtp_expn, &user_msg, &log_msg);
5524 done = smtp_handle_acl_fail(ACL_WHERE_EXPN, rc, user_msg, log_msg);
5527 BOOL save_log_testing_mode = f.log_testing_mode;
5528 f.address_test_mode = f.log_testing_mode = TRUE;
5529 (void) verify_address(deliver_make_addr(smtp_cmd_data, FALSE),
5530 smtp_out, vopt_is_recipient | vopt_qualify | vopt_expn, -1, -1, -1,
5532 f.address_test_mode = FALSE;
5533 f.log_testing_mode = save_log_testing_mode; /* true for -bh */
5542 if (!fl.tls_advertised)
5544 done = synprot_error(L_smtp_protocol_error, 503, NULL,
5545 US"STARTTLS command used when not advertised");
5549 /* Apply an ACL check if one is defined */
5551 if ( acl_smtp_starttls
5552 && (rc = acl_check(ACL_WHERE_STARTTLS, NULL, acl_smtp_starttls,
5553 &user_msg, &log_msg)) != OK
5556 done = smtp_handle_acl_fail(ACL_WHERE_STARTTLS, rc, user_msg, log_msg);
5560 /* RFC 2487 is not clear on when this command may be sent, though it
5561 does state that all information previously obtained from the client
5562 must be discarded if a TLS session is started. It seems reasonable to
5563 do an implied RSET when STARTTLS is received. */
5565 incomplete_transaction_log(US"STARTTLS");
5566 cancel_cutthrough_connection(TRUE, US"STARTTLS received");
5567 reset_point = smtp_reset(reset_point);
5569 cmd_list[CMD_LIST_STARTTLS].is_mail_cmd = FALSE;
5571 /* There's an attack where more data is read in past the STARTTLS command
5572 before TLS is negotiated, then assumed to be part of the secure session
5573 when used afterwards; we use segregated input buffers, so are not
5574 vulnerable, but we want to note when it happens and, for sheer paranoia,
5575 ensure that the buffer is "wiped".
5576 Pipelining sync checks will normally have protected us too, unless disabled
5577 by configuration. */
5579 if (receive_smtp_buffered())
5582 debug_printf("Non-empty input buffer after STARTTLS; naive attack?\n");
5583 if (tls_in.active.sock < 0)
5584 smtp_inend = smtp_inptr = smtp_inbuffer;
5585 /* and if TLS is already active, tls_server_start() should fail */
5588 /* There is nothing we value in the input buffer and if TLS is successfully
5589 negotiated, we won't use this buffer again; if TLS fails, we'll just read
5590 fresh content into it. The buffer contains arbitrary content from an
5591 untrusted remote source; eg: NOOP <shellcode>\r\nSTARTTLS\r\n
5592 It seems safest to just wipe away the content rather than leave it as a
5593 target to jump to. */
5595 memset(smtp_inbuffer, 0, IN_BUFFER_SIZE);
5597 /* Attempt to start up a TLS session, and if successful, discard all
5598 knowledge that was obtained previously. At least, that's what the RFC says,
5599 and that's what happens by default. However, in order to work round YAEB,
5600 there is an option to remember the esmtp state. Sigh.
5602 We must allow for an extra EHLO command and an extra AUTH command after
5603 STARTTLS that don't add to the nonmail command count. */
5606 if ((rc = tls_server_start(&s)) == OK)
5608 if (!tls_remember_esmtp)
5609 fl.helo_seen = fl.esmtp = fl.auth_advertised = f.smtp_in_pipelining_advertised = FALSE;
5610 cmd_list[CMD_LIST_EHLO].is_mail_cmd = TRUE;
5611 cmd_list[CMD_LIST_AUTH].is_mail_cmd = TRUE;
5612 cmd_list[CMD_LIST_TLS_AUTH].is_mail_cmd = TRUE;
5613 if (sender_helo_name)
5615 sender_helo_name = NULL;
5616 host_build_sender_fullhost(); /* Rebuild */
5617 set_process_info("handling incoming TLS connection from %s",
5618 host_and_ident(FALSE));
5621 (sender_host_address ? protocols : protocols_local)
5623 ? pextend + (sender_host_authenticated ? pauthed : 0)
5625 + (tls_in.active.sock >= 0 ? pcrpted : 0)
5628 sender_host_auth_pubname = sender_host_authenticated = NULL;
5629 authenticated_id = NULL;
5630 sync_cmd_limit = NON_SYNC_CMD_NON_PIPELINING;
5631 DEBUG(D_tls) debug_printf("TLS active\n");
5632 break; /* Successful STARTTLS */
5635 (void) smtp_log_tls_fail(s);
5637 /* Some local configuration problem was discovered before actually trying
5638 to do a TLS handshake; give a temporary error. */
5642 smtp_printf("454 TLS currently unavailable\r\n", FALSE);
5646 /* Hard failure. Reject everything except QUIT or closed connection. One
5647 cause for failure is a nested STARTTLS, in which case tls_in.active remains
5648 set, but we must still reject all incoming commands. Another is a handshake
5649 failure - and there may some encrypted data still in the pipe to us, which we
5650 see as garbage commands. */
5652 DEBUG(D_tls) debug_printf("TLS failed to start\n");
5653 while (done <= 0) switch(smtp_read_command(FALSE, GETC_BUFFER_UNLIMITED))
5656 log_write(L_smtp_connection, LOG_MAIN, "%s closed by EOF",
5657 smtp_get_connection_info());
5658 smtp_notquit_exit(US"tls-failed", NULL, NULL);
5662 /* It is perhaps arguable as to which exit ACL should be called here,
5663 but as it is probably a situation that almost never arises, it
5664 probably doesn't matter. We choose to call the real QUIT ACL, which in
5665 some sense is perhaps "right". */
5668 f.smtp_in_quit = TRUE;
5671 && ((rc = acl_check(ACL_WHERE_QUIT, NULL, acl_smtp_quit, &user_msg,
5672 &log_msg)) == ERROR))
5673 log_write(0, LOG_MAIN|LOG_PANIC, "ACL for QUIT returned ERROR: %s",
5676 smtp_respond(US"221", 3, TRUE, user_msg);
5678 smtp_printf("221 %s closing connection\r\n", FALSE, smtp_active_hostname);
5679 log_write(L_smtp_connection, LOG_MAIN, "%s closed by QUIT",
5680 smtp_get_connection_info());
5685 smtp_printf("554 Security failure\r\n", FALSE);
5688 tls_close(NULL, TLS_SHUTDOWN_NOWAIT);
5693 /* The ACL for QUIT is provided for gathering statistical information or
5694 similar; it does not affect the response code, but it can supply a custom
5698 smtp_quit_handler(&user_msg, &log_msg);
5704 smtp_rset_handler();
5705 cancel_cutthrough_connection(TRUE, US"RSET received");
5706 reset_point = smtp_reset(reset_point);
5713 smtp_printf("250 OK\r\n", FALSE);
5717 /* Show ETRN/EXPN/VRFY if there's an ACL for checking hosts; if actually
5718 used, a check will be done for permitted hosts. Show STARTTLS only if not
5719 already in a TLS session and if it would be advertised in the EHLO
5724 smtp_printf("214-Commands supported:\r\n", TRUE);
5728 Ustrcat(buffer, US" AUTH");
5730 if (tls_in.active.sock < 0 &&
5731 verify_check_host(&tls_advertise_hosts) != FAIL)
5732 Ustrcat(buffer, US" STARTTLS");
5734 Ustrcat(buffer, US" HELO EHLO MAIL RCPT DATA BDAT");
5735 Ustrcat(buffer, US" NOOP QUIT RSET HELP");
5736 if (acl_smtp_etrn) Ustrcat(buffer, US" ETRN");
5737 if (acl_smtp_expn) Ustrcat(buffer, US" EXPN");
5738 if (acl_smtp_vrfy) Ustrcat(buffer, US" VRFY");
5739 smtp_printf("214%s\r\n", FALSE, buffer);
5745 incomplete_transaction_log(US"connection lost");
5746 smtp_notquit_exit(US"connection-lost", US"421",
5747 US"%s lost input connection", smtp_active_hostname);
5749 /* Don't log by default unless in the middle of a message, as some mailers
5750 just drop the call rather than sending QUIT, and it clutters up the logs.
5753 if (sender_address || recipients_count > 0)
5754 log_write(L_lost_incoming_connection, LOG_MAIN,
5755 "unexpected %s while reading SMTP command from %s%s%s D=%s",
5756 f.sender_host_unknown ? "EOF" : "disconnection",
5757 f.tcp_in_fastopen_logged
5760 ? f.tcp_in_fastopen_data ? US"TFO* " : US"TFO "
5762 host_and_ident(FALSE), smtp_read_error,
5763 string_timesince(&smtp_connection_start)
5767 log_write(L_smtp_connection, LOG_MAIN, "%s %slost%s D=%s",
5768 smtp_get_connection_info(),
5769 f.tcp_in_fastopen && !f.tcp_in_fastopen_logged ? US"TFO " : US"",
5771 string_timesince(&smtp_connection_start)
5782 done = synprot_error(L_smtp_protocol_error, 503, NULL,
5783 US"ETRN is not permitted inside a transaction");
5787 log_write(L_etrn, LOG_MAIN, "ETRN %s received from %s", smtp_cmd_argument,
5788 host_and_ident(FALSE));
5790 if ((rc = acl_check(ACL_WHERE_ETRN, NULL, acl_smtp_etrn,
5791 &user_msg, &log_msg)) != OK)
5793 done = smtp_handle_acl_fail(ACL_WHERE_ETRN, rc, user_msg, log_msg);
5797 /* Compute the serialization key for this command. */
5799 etrn_serialize_key = string_sprintf("etrn-%s\n", smtp_cmd_data);
5801 /* If a command has been specified for running as a result of ETRN, we
5802 permit any argument to ETRN. If not, only the # standard form is permitted,
5803 since that is strictly the only kind of ETRN that can be implemented
5804 according to the RFC. */
5806 if (smtp_etrn_command)
5810 etrn_command = smtp_etrn_command;
5811 deliver_domain = smtp_cmd_data;
5812 rc = transport_set_up_command(&argv, smtp_etrn_command, TRUE, 0, NULL,
5813 US"ETRN processing", &error);
5814 deliver_domain = NULL;
5817 log_write(0, LOG_MAIN|LOG_PANIC, "failed to set up ETRN command: %s",
5819 smtp_printf("458 Internal failure\r\n", FALSE);
5824 /* Else set up to call Exim with the -R option. */
5828 if (*smtp_cmd_data++ != '#')
5830 done = synprot_error(L_smtp_syntax_error, 501, NULL,
5831 US"argument must begin with #");
5834 etrn_command = US"exim -R";
5835 argv = CUSS child_exec_exim(CEE_RETURN_ARGV, TRUE, NULL, TRUE,
5836 *queue_name ? 4 : 2,
5837 US"-R", smtp_cmd_data,
5838 US"-MCG", queue_name);
5841 /* If we are host-testing, don't actually do anything. */
5847 debug_printf("ETRN command is: %s\n", etrn_command);
5848 debug_printf("ETRN command execution skipped\n");
5850 if (user_msg == NULL) smtp_printf("250 OK\r\n", FALSE);
5851 else smtp_user_msg(US"250", user_msg);
5856 /* If ETRN queue runs are to be serialized, check the database to
5857 ensure one isn't already running. */
5859 if (smtp_etrn_serialize && !enq_start(etrn_serialize_key, 1))
5861 smtp_printf("458 Already processing %s\r\n", FALSE, smtp_cmd_data);
5865 /* Fork a child process and run the command. We don't want to have to
5866 wait for the process at any point, so set SIGCHLD to SIG_IGN before
5867 forking. It should be set that way anyway for external incoming SMTP,
5868 but we save and restore to be tidy. If serialization is required, we
5869 actually run the command in yet another process, so we can wait for it
5870 to complete and then remove the serialization lock. */
5872 oldsignal = signal(SIGCHLD, SIG_IGN);
5874 if ((pid = exim_fork(US"etrn-command")) == 0)
5876 smtp_input = FALSE; /* This process is not associated with the */
5877 (void)fclose(smtp_in); /* SMTP call any more. */
5878 (void)fclose(smtp_out);
5880 signal(SIGCHLD, SIG_DFL); /* Want to catch child */
5882 /* If not serializing, do the exec right away. Otherwise, fork down
5883 into another process. */
5885 if ( !smtp_etrn_serialize
5886 || (pid = exim_fork(US"etrn-serialised-command")) == 0)
5888 DEBUG(D_exec) debug_print_argv(argv);
5889 exim_nullstd(); /* Ensure std{in,out,err} exist */
5890 execv(CS argv[0], (char *const *)argv);
5891 log_write(0, LOG_MAIN|LOG_PANIC_DIE, "exec of \"%s\" (ETRN) failed: %s",
5892 etrn_command, strerror(errno));
5893 _exit(EXIT_FAILURE); /* paranoia */
5896 /* Obey this if smtp_serialize and the 2nd fork yielded non-zero. That
5897 is, we are in the first subprocess, after forking again. All we can do
5898 for a failing fork is to log it. Otherwise, wait for the 2nd process to
5899 complete, before removing the serialization. */
5902 log_write(0, LOG_MAIN|LOG_PANIC, "2nd fork for serialized ETRN "
5903 "failed: %s", strerror(errno));
5907 DEBUG(D_any) debug_printf("waiting for serialized ETRN process %d\n",
5909 (void)wait(&status);
5910 DEBUG(D_any) debug_printf("serialized ETRN process %d ended\n",
5914 enq_end(etrn_serialize_key);
5915 exim_underbar_exit(EXIT_SUCCESS);
5918 /* Back in the top level SMTP process. Check that we started a subprocess
5919 and restore the signal state. */
5923 log_write(0, LOG_MAIN|LOG_PANIC, "fork of process for ETRN failed: %s",
5925 smtp_printf("458 Unable to fork process\r\n", FALSE);
5926 if (smtp_etrn_serialize) enq_end(etrn_serialize_key);
5930 smtp_printf("250 OK\r\n", FALSE);
5932 smtp_user_msg(US"250", user_msg);
5934 signal(SIGCHLD, oldsignal);
5939 done = synprot_error(L_smtp_syntax_error, 501, NULL,
5940 US"unexpected argument data");
5944 /* This currently happens only for NULLs, but could be extended. */
5947 done = synprot_error(L_smtp_syntax_error, 0, NULL, /* Just logs */
5948 US"NUL character(s) present (shown as '?')");
5949 smtp_printf("501 NUL characters are not allowed in SMTP commands\r\n",
5956 if (smtp_inend >= smtp_inbuffer + IN_BUFFER_SIZE)
5957 smtp_inend = smtp_inbuffer + IN_BUFFER_SIZE - 1;
5958 c = smtp_inend - smtp_inptr;
5959 if (c > 150) c = 150; /* limit logged amount */
5961 incomplete_transaction_log(US"sync failure");
5962 log_write(0, LOG_MAIN|LOG_REJECT, "SMTP protocol synchronization error "
5963 "(next input sent too soon: pipelining was%s advertised): "
5964 "rejected \"%s\" %s next input=\"%s\"",
5965 f.smtp_in_pipelining_advertised ? "" : " not",
5966 smtp_cmd_buffer, host_and_ident(TRUE),
5967 string_printing(smtp_inptr));
5968 smtp_notquit_exit(US"synchronization-error", US"554",
5969 US"SMTP synchronization error");
5970 done = 1; /* Pretend eof - drops connection */
5974 case TOO_MANY_NONMAIL_CMD:
5975 s = smtp_cmd_buffer;
5976 while (*s != 0 && !isspace(*s)) s++;
5977 incomplete_transaction_log(US"too many non-mail commands");
5978 log_write(0, LOG_MAIN|LOG_REJECT, "SMTP call from %s dropped: too many "
5979 "nonmail commands (last was \"%.*s\")", host_and_ident(FALSE),
5980 (int)(s - smtp_cmd_buffer), smtp_cmd_buffer);
5981 smtp_notquit_exit(US"bad-commands", US"554", US"Too many nonmail commands");
5982 done = 1; /* Pretend eof - drops connection */
5985 #ifdef SUPPORT_PROXY
5986 case PROXY_FAIL_IGNORE_CMD:
5987 smtp_printf("503 Command refused, required Proxy negotiation failed\r\n", FALSE);
5992 if (unknown_command_count++ >= smtp_max_unknown_commands)
5994 log_write(L_smtp_syntax_error, LOG_MAIN,
5995 "SMTP syntax error in \"%s\" %s %s",
5996 string_printing(smtp_cmd_buffer), host_and_ident(TRUE),
5997 US"unrecognized command");
5998 incomplete_transaction_log(US"unrecognized command");
5999 smtp_notquit_exit(US"bad-commands", US"500",
6000 US"Too many unrecognized commands");
6002 log_write(0, LOG_MAIN|LOG_REJECT, "SMTP call from %s dropped: too many "
6003 "unrecognized commands (last was \"%s\")", host_and_ident(FALSE),
6004 string_printing(smtp_cmd_buffer));
6007 done = synprot_error(L_smtp_syntax_error, 500, NULL,
6008 US"unrecognized command");
6012 /* This label is used by goto's inside loops that want to break out to
6013 the end of the command-processing loop. */
6016 last_was_rej_mail = was_rej_mail; /* Remember some last commands for */
6017 last_was_rcpt = was_rcpt; /* protocol error handling */
6021 return done - 2; /* Convert yield values */
6027 authres_smtpauth(gstring * g)
6029 if (!sender_host_authenticated)
6032 g = string_append(g, 2, US";\n\tauth=pass (", sender_host_auth_pubname);
6034 if (Ustrcmp(sender_host_auth_pubname, "tls") == 0)
6035 g = authenticated_id
6036 ? string_append(g, 2, US") x509.auth=", authenticated_id)
6037 : string_cat(g, US") reason=x509.auth");
6039 g = authenticated_id
6040 ? string_append(g, 2, US") smtp.auth=", authenticated_id)
6041 : string_cat(g, US", no id saved)");
6043 if (authenticated_sender)
6044 g = string_append(g, 2, US" smtp.mailfrom=", authenticated_sender);
6052 /* End of smtp_in.c */